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8043655 | Hemocyte aggregation in the solitary ascidian Halocynthia roretzi: plasma factors, magnesium ion, and Met-Lys-bradykinin induce the aggregation. | Hemocytes of the ascidian Halocynthia roretzi undergo aggregation in hemolymph that has been collected from the body through the tunic. To investigate the mechanisms involved, we first established two methods of measuring hemocyte aggregation. In one method, hemocyte aggregation was quantified by its reduction of light scattering intensity as measured with a fluorescence spectrophotometer. In the other method, the increase of transmittance accompanying aggregation was measured with an ELISA reader. We found that ascidian plasma, Mg2+, and Met-Lys-bradykinin can induce the hemocytes of H. roretzi to aggregate. The aggregation induced by any of these three substances was inhibited by EDTA, N-ethylmaleimide, and cytochalasin B. Lipopolysaccharide had little inducing effect. We also demonstrated that, when H. roretzi plasma was treated with trypsin, low molecular weight aggregation-inducing substances were produced. These results suggest that metal ions and peptide-like substances present in the hemolymph play essential roles in the progression of hemocyte aggregation of H. roretzi. |
8043653 | Sites of strand breakage in DNA irradiated by fast neutrons. | Therapeutic fast neutrons are densely ionizing particles, with a high relative biological effectiveness relative to 60Co gamma rays (RBE) and a low oxygen enhancement ratio (OER). The molecular basis of their properties is not yet entirely understood. In a previous work, we have shown that neutrons induce a different number of DNA frank strand breaks as compared to gamma photons, and we have revealed the presence of breaks due to the direct effects of neutrons. In the present work, we searched for eventual differences in the chemical nature of the attacked sites in DNA irradiated in oxygenated diluted solution. We compare our results with neutrons to those previously reported by other authors using gamma- or X-rays. Using sequencing gel electrophoresis of short natural DNA restriction fragments, or synthetic oligonucleotides, we have shown that, in the case of neutrons, the attack occurs with almost the same probability, at each nucleotide, as reported for gamma- and X-rays. The doubling of bands in the bottom of gels shows the presence of two types of termini, the 3'-phosphate and the 3'-phosphoglycolate. Upon neutron irradiation, the 3'-phosphate end appears with a higher yield than the 3'-phosphoglycolate, whereas equal amounts were obtained with gamma- or X-rays. |
8043652 | Dye-hydrophobic hapten conjugate/anti-dye antibody complex as immunogen: preparation of hydrophobic hapten-specific monoclonal antibodies. | In order to induce the production of antibodies specific for small molecules, it is common to link them to a protein. However, when the small molecule is very hydrophobic it is extremely difficult to prepare such a conjugate. Here, we describe a simple way to obtain an antigenic conjugate under controlled conditions: in a first step a very hydrophobic hapten, cholanic acid, is linked to a dye, basilen blue, in organic solvent; in a second step the cholanic acid-basilen blue conjugate is dissolved in phosphate buffered saline and mixed with rabbit polyclonal anti-basilen blue antibodies previously raised in rabbits against basilen blue-key-hole limpet hemocyanin conjugate. Such a complex, which dissociates very slowly, appears to be a good immunogen in mice. Anti-cholanyl residue monoclonal antibodies were produced and characterized. |
8043651 | New substrates of papain, based on the conserved sequence of natural inhibitors of the cystatin family. | A series of peptide substrates with different fluorogenic leaving groups has been synthesized. The peptide moiety in these substrates mimics a highly conserved sequence (QVVAG) in the natural reversible inhibitors of cysteine proteinases, the cystatins, that participates to the tight binding of target proteinases. This sequence is invariably cleaved at the A-G bond when synthetic peptides containing it were incubated with papain. AEC and AMC fluorophores were therefore attached to the Ala residue to construct new substrates for cysteine proteinases. The solubility of the resulting substrates was improved by attaching a N-terminal gluconoyl group, or by introducing an arginyl residue at P5 (nomenclature of Schechter I, Berger A (1967) Biochem Biophys Res Commun 27, 157-162). Neither induced significant changes in the kcat/Km values with papain. Those values were all in the 10(5) M-1 s-1 range. The kcat/Km was increased 10-50-fold by using substrates with intramolecularly quenched fluorescence. With these, the enzyme specificity on both sides of the scissile bond can be investigated. The substrate Abz-QVVAGA-EDDnp is among the most sensitive papain substrates ever reported, with a kcat/Km value of 29 10(6) M-1 s-1. The positioning and conformation of the bound QVVA moiety within the active site of papain were predicted by molecular modelling using the X-ray coordinates of a peptide inhibitor-papain complex. |
8043650 | Comparison of solution structure of free and complexed lac operator by molecular modelling with NMR constraints. | The structure difference between the free operator of the lac system d(GCTCACAAT).d(ATTGTGAGC) and the same operator complexed to the headpiece of the lac repressor has been investigated by 2-D-1H NMR spectroscopy in conjunction with molecular modelling in internal coordinates (JUMNA). The free and complexed operator adopt both a right-handed B helical conformation, but a more detailed analysis of the conformational parameters using the Curves program shows striking differences in the groove geometries, the rises, the twists and the total bending. |
8043649 | Fluorescence study on the non-specific binding of cyclic-AMP receptor protein to DNA: effect of pH. | The binding of the cyclic-AMP receptor protein (CRP) of Escherichia coli to a non-specific DNA fragment of 46 base pairs has been studied using fluorescence spectroscopy. The equilibrium binding constant was found to be several orders of magnitude lower than in the specific binding to a DNA fragment of the same size. The salt dependence of the equilibrium binding constant indicates that the CRP makes an identical number (8) of ion pairs to this non-specific DNA fragment in the presence and absence of cAMP. This number is larger than that previously found in the specific binding process. The effect of pH on the non-specific binding was investigated. The number of ion pairs does not vary between pH 6 and 8. From the variation of the binding constant with pH it was deduced that two histidines are involved in the binding in the absence of cAMP. These are most probably the histidines 199 of each subunit. In the presence of cAMP, only one histidine participates in the binding process, indicating an asymmetric interaction between the two subunits of the CRP and the DNA. |
8043648 | Identification of the DNA-interacting sites of proteins: microsequencing of the peptides cross-linked to 5-bromouracil substituted DNA. | Photochemical induced cross-links between protein and nucleic acids are useful tools in the study of the protein-DNA interactions. The substitution of thymine by 5-bromouracil in DNA increases the photocross-linking yield, and reduces the direct damages to both DNA and proteins. Using the lac repressor-DNA non-specific interaction system, we have developed a procedure to identify the interaction site on the protein. Sensitive, accurate and inexpensive in time and material, this procedure is based on the possibility of sequencing peptides in the presence of a large excess of DNA. The obtained result (the implication of His 29) agrees with previous work. |
8043647 | Purification of an alpha-L-fucoside-binding protein from Rhizobium lupini. | Lectins associated with the bacterial cell surface of Rhizobium lupini strain LL13 were evidenced by erythrocyte agglutination, by aggregation of neoglycoprotein coated beads and by spectrofluorimetry using fluoresceinylated neoglycoproteins. At pH 5.0, a specific binding of the fluorescein-labelled neoglycoprotein bearing alpha-L-fucose was observed. The binding of this labelled neoglycoprotein is a saturable phenomenon and is inhibited by the same unlabelled neoglycoprotein. Extracts of R lupini obtained by disrupting a bacterial pellet through a French press were stabilized at pH 5.6 by gel filtration and purified to homogeneity by affinity chromatography on Agarose A4 substituted with alpha-L-fucose. A protein with a M(r) approximately 19,000 was specifically eluted from this affinity column with L-fucose. Isoelectric focusing of this sample yielded a single band with pI near 6.7. This protein specifically aggregated L-Fuc-BSA-coated microspheres. The results obtained in the present study indicate that we have purified from Rhizobium lupini strain LL13, a L-fucose binding protein as a lectin. |
8043646 | Some aspects of carbohydrate metabolism in the brain. | A convenient physiology of the nervous system closely depends on the availability of glucose, the lack of which quickly results in syncope and death. Carbohydrate metabolism in the brain was long thought of as being specific and different from liver carbohydrate metabolism. The present report tries to summarize current data and advances in our knowledge about carbohydrate metabolism. Glucose is brought to the brain by blood flowing through a special network of arteries and is quickly catabolized by the glycolytic and tricarboxylic acid cycle pathways to synthesize energy. It is also used in the synthesis of numerous amino acids, nucleotides and NADPH. Glucose can be polymerized into glycogen in the brain. The nerve tissue is capable of synthesizing glucose-6-phosphate in the gluconeogenic pathway since the fructose-1,6-bisphosphatase, the key enzyme believed to be absent, is actually active and has been purified up to electrophoretic homogeneity. Moreover, the possibility of free glucose synthesis by astrocytes exists. Although the exact role of glycogen in the brain is not totally clear, it is known that the polysaccharide content generally decreases when the functioning of the brain is stimulated and increases in sedative state. This carbohydrate can therefore serve as an indicator for the level of brain activity. Through the administration of methionine sulfoximine, it is possible to increase the amount of glycogen in the brain massively and obtain particles similar to those found in the liver. These in vivo findings have been confirmed by studies based on cultured astrocytes. It has been shown with cultured astrocytes that glutamate increases glycogen synthesis in a pathway which still remains to be elucidated. Brain carbohydrate metabolism is thus in many ways similar to liver carbohydrate metabolism. The astrocyte constitutes the main cell implicated in this metabolism. Improvement in our knowledge about brain carbohydrate metabolism should spread the use of brain glucose metabolism in the diagnosis of certain diseases. |
8043644 | [Relation between neurogenesis and electrical responses of olfactory receptors]. | Structural and functional changes in olfactory epithelium of laboratory mice were studied following the treatment of nasal cavity with zinc sulphate. Different concentrations of zinc sulphate caused olfactory epithelium cells destruction, moreover the degree of this destruction depended on concentration. Direct dependence between morphological regeneration and the EOG amplitude increase was observed after the treatment with 1% zinc sulphate. The epithelium regeneration after the treatment with higher concentration (3 and 5%) was slower and the EOG amplitude fell behind the increase of the olfactory epithelium thickness. The application of different olfactory stimuli allowed to establish that the rate of reactions re-establishment differed with the odorous. |
8043645 | [Some regularities in the distribution of autooscillation frequencies in the neuromuscular system]. | This paper is devoted to the problem of biofeedback and self-regulation in the human neuromuscular system. On the base of our experimental data we revealed the existence of the three informative frequency band in the range 100-150, 140-210 and 180-300 p.s. The task of measuring of the autooscillations is solved by inserting the appropriate muscle area as the positive elements of electromechanical feedback generator including the amplifier and two electromechanical transducers. The tested muscle group being strained and actively or passively relaxed in turn. The integrated relationships between the autooscillations of the muscle group of the right and left hand turned out the family of straight lines. We got a mathematical expressions for the characteristics curves with the discrete constant coefficient. |
8043643 | [Endocrine control of olfactory reception]. | There was studied the endocrine control of the first stage of olfactory reception. In the experiments with male castration it was detected that the olfactory receptor cells had a slow tonic influence on sex steroid hormones. The most dependent on the hormone control were the olfactory cells sensitive to natural stimuli. From the morphological data it was supposed that this influence was realized through the control of process of neurogenesis of the olfactory cells. On another experimental modelestral females. Which had quick changes of sex hormone level, it was detected that the reason for the olfactory sensitivity to odor variations during estrus cycle did not localized in the peripheral part of the olfactory system. Apparently the quick endocrine influence was realized at the central part of the olfactory system. |
8043642 | [Controlled effect of an impulse electromagnetic field on the central nervous system]. | Faint influences of impulses (1 ms) electromagnetic fields (173 A/m) with dynamic frequency-impulse modulation, which is regulated by feedback from electrocorticogram, and influences with fixed frequency of impulses run infra-low range affect on changing of current function state of central nervous system in different ways, is established. The white rats in the sleep-wake cycle were used in experiments. Besides, the first regimen of influence is more effective for changing of character of bioelectrical activity of cortex of head brain. The second one-for support of current processes of synchronization. |
8043641 | [Study of fine structure changes in the human constant electrical field in a series of eye diseases]. | Using external non-polarized electrodes Ag/AgCl the potential difference was measured between four measure points and a referent point, situated on the skin of humans with normal sight function and of ones suffering from cataracta, glaucoma and toxic neurite. Three points, situated on the face skin and a point at the corner of the nail couch of the forefingers of both hands were used as the measure points. The referent point was always situated on the neck in the place of the crossing of the cowl muscle and clavicle-nipple one. The investigation has shown that the potential difference between all the measured points and the referent point varies for all the diseases, mentioned above, and hence, the fine structure of the electric field changes in a different way at all these diseases. Thus, a regulator of life processes the constant electric field of the organism-searches all the pathologic changes and gives broad possibilities for the diagnostics of both the whole organism state and a particular organ one. |
8043640 | [Nonparametric model of regulating the level of arterial pressure by the fastest mechanism system]. | At present paper we consider the nonparametric mathematical model which describes the function of fastest mechanisms of arterial pressure regulation (baroreceptor mechanism, chemoreceptor mechanism, "relaxation of tension", ischemic reaction of central nervous system). For the model we define the dynamic regimens for arterial pressure behaviour and discuss the role of mechanisms in realization of the normal, hypertension and hypotension regimens. As it was shown the disorders in thresholds relations for mechanism's switching into regulation process can't lead to the appearance of the oscillation fluctuations in arterial pressure behaviour but it can lead to the realization of the trigger regimens. |
8043638 | [Mathematical modeling of the interaction of local anesthetics with the surface of nerve fiber biomembranes]. | Theoretical analysis and mathematical modelling of conductor anesthesia has been performed. It has been established that mathematical models explicity taking into account the form and the size of molecules (through molar volumes) and the energy of intermolecular interaction with biomembrane surface of a nerve fiber (through normal boiling temperatures) are the most close to electrophysiology data obtained by measuring of minimal blocking concentrations of anesthetics in inter- or intracell solutions, causing complete isolation of a pain spike in the fiber. Computation based on an improved additive systematics produced physical-chemical descriptors for construction of mathematical models. The determined parameters conform to experimental data in crucial features molar volumes and normal boiling temperatures for analyzed compounds. Predictions possibilities and restrictions of suggested approach for search for new effective anesthetics and structures with higher indices of biological activity has been analyzed. |
8043637 | [The mechanism of synchronizing yeast cell cultures with EHF-radiation]. | We investigated the development of a Saccharomyces carlsbergensis yeast cell culture irradiated with EHF electromagnetic waves. Short-term EHF action was found to produce change of the budding period. The cell-cycles synchronization occurred after longer irradiation. Extraordinary prolonged synchrony of cycles (more then 20 cycles) was explained as result of the culture self-organization connected with activation of intercellular interaction. |
8043636 | [Mechanism of microwave radiation absorption by biological membranes]. | A new mechanism is proposed in order to explain the influence of microwave on biological membranes. The mechanism is based on transit time effects of carriers performing the ionic transport. Accounting for the carrier transit time shows that the biological membrane can be considered as a dielectric diode with conductivity and dielectric permissivity dependent on the transit angles, leading to additional absorption. |
8043635 | [Recording of surface potential changes in erythrocyte membranes from patients with insulin-dependent diabetes mellitus using a spin probe method]. | Changes in surface potential of erythrocyte membranes were studied by a positively charged analog as a spin probe. Insulin-dependent diabetes mellitus (IDDM) patients demonstrated a significant increase (by 16 +/- 2.0 mV) in negative surface potential as compared to the control. An important role of this phenomenon in pathogenesis of IDDM is discussed. |
8043634 | [Thermostability of erythrocyte membranes in the presence of ethanol]. | Differential scanning microcalorimetry was used to show a destabilizing effect of ethanol on erythrocyte membrane proteins. The thermostability of the membrane cooperative unit, with the main protein being band 3 integral protein, was decreased most significantly, which was probably related to a disturbance in protein--lipid complementary. At sufficiently high ethanol concentrations the denaturational changes in the membrane proteins resulted in lysis of red blood cells preceeding at several stages: morphological changes in cells, as well as swelling and the lysis, proper. The activation energy of the ethanol-induced lysis as determined from the temperature dependence of the apparent hemolysis rate constant was equal to 150 +/- 20 kJmol-1 at 5.1 M ethanol concentration. This corresponded to the activation energy of the protein denaturation. |
8043633 | [Mossbauer data on the effect of NAD.H on the state of iron in bacteria]. | The state of Fe of bacterial cultures of different systematic positions (Bacillus megaterium, Bacillus polymyxa, Pseudomonas putida, Pseudomonas fluorescens, Alcaligenes faecalis, Arthrobacter siderocapsulatus) grown on the medium containing Fe(III) citrate (up to 100 mg/l) with additional or without NAD.H was studied. The samples were in damp air-dry, second moistened, dried at 383 K states. Spectra have been obtained at 290 K and 100-200 K. The studied microorganisms have two types of atoms of Fe(III) which dissociated into protoplasm or into cell slug at damp state. All studied microorganisms except Arthrobacter siderocapsulatus do not reduce iron at all variants of experiments. Arthrobacter siderocapsulatus reduces about 50% of cell iron only the presence of NAD.H creating two types of Fe(II) complexes firmly connected with cell. |
8043632 | [Extracellular photoreceptor potential of albino rats]. | In this study methodically simple model of mammalian's total rods photoreceptor potential obtained by the known methods of outside electrical activity suppression by barium ions and sodium aspartate is offered. The farmacological analysis of that potential with using of ions-blockers of the potential-dependent conductances demonstrated that the offered potential consisted of the same components as the known intracellular responses. |
8043631 | [The effect of structure of benzimidazoles on the character of forming intramolecular cross-links in DNA and chromatin]. | An investigation of a number of benzimidazole class preparations, being distinguished by a position of aminomethyl substitutes, has been carried out. It has been shown, that the non-substituted preparation BIO-10 does not form UV-cross-links in DNA and chromatine; BIO-40, having one substitute in the position 2, causes the formation of inter-molecular cross-links DNA-DNA. The preparation BIO-50, having 2 aminomethyl groups in the imidazole nucleus positions 2 and 6, forms cross-links DNA-DNA and DNA-protein in chromatine. The generation of radicals by the preparations BIO-10 and BIO-50 has been studied by the EPR-method by use of spin trap. It has been demonstrated, that BIO-10, unlike BIO-50, actively generates superoxide. A supposition has been made, that an UV-formation of superoxide-radical in the presence of BIO-10 might be a reason of DNA-macromolecule destruction. |
8043630 | [Study of the interaction of DNA with copper ions using IR- and Raman spectroscopy]. | DNA with Cu2+ ions in solution and films is studied by IR and Raman spectroscopy at different relative humidities (R.H. = 51 divided by 98%). DNA complexed with Cu2+ ions is shown to transit to the double-helix conformation, passing A-form, the water content per nucleotide (n) being essentially larger: 12 for Cu2+/P = 0.4 (n = 8 for DNA without ions). Cu2+ decrease the biopolymer hydration at R.H. 50-76% interactions with Cu2+ are stated to depend on the hydration degree of macromolecules. The analysis of the absorption band shifts of Raman spectra evidences the changes in the base torsion angle around the glycoside bond to the values characteristic of the syn-conformation and the interaction both with phosphates and nitrogen bases. |
8043629 | [A mechanism for dual-stage kinetics of actomyosin superprecipitation]. | It has been shown that a step-like superprecipitation of actomyosin is determined by parallel processes of two types of superprecipitation: "immediate", which is characterized by a rapid one-step increase in turbidity, and "spontaneous", when slow increase growth of turbidity follows a clear phase. It is suggested that this phenomenon is based on heterogeneous nature of particle sizes in the original suspension, which, under certain conditions, leads to "constriction" of larger particles and "clearing" of smaller ones. |
8043628 | Clinical and tomographic findings in vascular dementia. | Vascular dementia (VD) may arise as a sequel to any form of cerebrovascular disease. Since only some patients with cerebrovascular disease will eventually develop dementia, we studied the morphological and clinical findings associated with dementia in cerebrovascular patients. The relationship between these factors and the dementia syndrome was evaluated in 25 patients with VD, and 68 non demented subjects with a history of cerebral ischemic attacks. We found that VD was significantly associated with white matter lesions and atrophy on CT-scan, and a high prevalence of frontal lobe symptoms and signs. |
8043627 | Invertebrates can tell us something about senescence. | Senescence is a ubiquitous phenomenon, i.e., all vertebrates and invertebrates will ultimately manifest it. Any attempt to answer the question of adaptive significance of the aging process must take into account the universality of and change in the DNA molecule that governs, integrates, regulates and ensures the vitality of all organisms. With invertebrates and from the comparative viewpoint, there are examples of: 1) rapid senescence and sudden death; 2) gradual senescence with definite life span; 3) negligible senescence; 4) genetic influence on life span, mortality rates, and age-related diseases. Although these characteristics are ascribed to invertebrates and vertebrates, this need not force upon invertebrates the organization, structure and eventual features of vertebrate senescence. "Invertebrate gerontologists" can thus, freely delve into certain unique aspects of what may be the more primitive mechanisms of aging in invertebrates. In contrast, using the opposite strategy that is still problematic, i.e., linking invertebrate and vertebrate aging, seems to give us an approach to universality that might eventually reveal more readily obvious and homologous kinship. |
8043626 | Depression in stroke patients with left and right hemisphere lesions. A study in geriatric rehabilitation in-patients. | To analyze possible differences in depression rate and symptomatology in stroke patients with left and right hemisphere lesions, ninety-three patients in geriatric rehabilitation wards with a mean age of 76 years were studied. A clinical psychiatric examination was used together with two depression rating scales. Depression prevalence was 46%, and there was no difference between left and right hemisphere lesions. Mean depression scores in the two rating scales showed no significant difference regarding location of lesions. It is concluded that in this elderly, moderately handicapped, stroke population there was no significant difference in depression rate between patients with left and right hemisphere lesions. |
8043625 | Androgyny and psychological well-being among older and younger Japanese adults. | The present study examined Gutmann's role reversal theory and Sinnott's role blurring (androgyny) theory. A total of 384 Japanese community aged were compared to 289 students using the Bem Sex Role Inventory. The Rosenberg Self-Esteem Scale was used to measure psychological well-being. Masculinity was higher among men than women, and the old showed higher femininity than the young. However, no significant cohort by sex interaction was observed in either masculine or feminine scores. To examine the relationship between androgyny and psychological well-being, subjects were classified into androgynous, masculine, feminine and undifferentiated groups. Analysis of variance (sex role typing x sex x cohort) on self-esteem revealed a significant sex role typing effect. The androgynous men and women possessed the highest self-esteem, followed by the masculine, feminine and undifferentiated men and women, in this order. Our results supported Sinnott's but not Gutmann's theory. |
8043624 | Did I unplug the iron or did I only look at it? External source monitoring across the adult life span. | Adult age differences in external source monitoring were examined using three types of materials differing in degree of salience. Young (mean age = 25.2 years), young-old (mean age = 66.0 years), and old adults (mean age = 74.7 years) learned organizable words, objects, and subject-performed tasks, with a blocked or random presentation. Later, subjects were asked to recognize the items and to identify their origins. Results indicated an age-related deficit in both item memory and external source monitoring as reflected by lower recognition performance, and more source confusion errors with increasing age. A strong positive relationship between episodic item memory and source memory was found for all age groups. Overall, the results suggest that age deficits in source monitoring may be determined by the same factors as age deficits in item memory. |
8043623 | Age-associated changes in human T cell phenotype and function. | We used a limiting dilution method to estimate the proportion of T lymphocytes that could respond to PHA by producing IL-2, in peripheral blood mononuclear cells from healthy adult donors ranging in age from 18 to 81 years. The donors were selected using the guidelines of the SENIEUR protocol to exclude samples from donors not in optimal health. The frequency of PHA responsive, IL-2 producing T cells was found to decline with age, even though there was no corresponding change in the proportions of cells expressing the CD3 or CD4 determinants. There was, however, a statistically significant increase in the proportion of CD4 and CD8 cells expressing the CD45R0 determinant, thought to be a marker for memory T cells, and a corresponding decline in cells expressing the CD45RA marker found on naive peripheral T cells. The decline in the proportion of mitogen-reactive T cells in older donors, although statistically significant, was smaller than that seen in studies of aging mice, probably because the assay conditions for human T cell function are preferentially stimulatory for memory T cells, which accumulate in old age. |
8043621 | Ventricle size and P300 in schizophrenia. | Both ventricular enlargement and reduced P3 amplitudes are consistent findings in schizophrenic patients, suggesting that the two measures reflect a common underlying pathophysiological process in schizophrenia. Investigating 14 stabilized schizophrenic outpatients, a relationship between the size of the lateral ventricles as well as of the third ventricle on CT scans and the auditory event-related P3 amplitude was, however, not found. This negative result suggests that ventricular enlargement and reduced P3 amplitudes in schizophrenics reflect different pathophysiological processes. It is assumed that the P3 amplitude is related rather to abnormalities in the temporal lobe of schizophrenic patients. |
8043620 | A long-term follow-up study of cerebrospinal fluid acetylcholinesterase in delirium. | Cerebrospinal fluid acetylcholinesterase (CSF AChE) was determined for elderly delirious patients during the acute stage and after a 1- and 4-year follow-up periods, and the AChE levels were compared with age-equivalent controls. The AChE levels measured during the index admission correlated with the length of life after delirium, suggesting that cholinergic dysfunction may have prognostic significance in delirious patients. Although the CSF AChE concentrations measured during the index admission were in the same range as in controls, we observed a declining trend in patients with various structural brain diseases during the follow-up period. The decreasing levels may reflect the progression of the underlying dementia in these patients. |
8043619 | Premorbid personality traits of men who develop unipolar or bipolar disorders. | In 1972, all Swiss males in the Canton of Zurich who reported for a compulsory medical examination for selection for military service were given the Freiburg Personality Inventory. This was repeated in half the sample on three subsequent occasions. From 1983 to 1988, an effort was made to identify all male psychiatric cases. There were 99 unipolars and 26 bipolars. The unipolars who had their age of onset after the personality testing displayed elevated scores on a constellation of symptoms labelled autonomic lability which consisted of items that correlated highly with neuroticism. The trait endured even when it was retested at age 36 years. The bipolars did not differ from the controls in any respect on any occasion. |
8043618 | Typus melancholicus as a personality characteristic of migraine patients. | The present study tests the hypothesis that persons suffering from migraine show personality traits of the "typus melancholicus" (melancholy type, Tellenbach). Ninety-six migraineurs were compared to 115 normal subjects, 36 neurotics, 38 psychosomatic patients, 52 patients suffering from other pain disorders and 38 unipolar depressives, matched for sex, age and social status. Several already standardized personality inventories were used (MP-T, D-S, FAPK, IAF, GT-S), as well as a questionnaire constructed especially to record typus-melancholicus traits in migraineurs. The results of univariate and multivariate methods of comparison clearly confirmed the hypothesis. In contrast to normal subjects, neurotic, psychosomatic and pain patients, migraineurs showed significantly higher levels of typus-melancholicus traits, whereas they did not differ from the unipolar depressives in this respect. |
8043617 | Partners in adversity. IV. Coping and mood. | This paper presents details of an interviewer-based measure of coping, completed in the context of a study examining the mental health of three groups of married women following their exposure to recent severe adversity. For one group a marital partner had recently died and for another group a marital partner had recently experienced a myocardial infarction. The third group consisted of those women recently entering a Women's Aid refuge. Initial interviews were completed about 6 weeks following event experience. Coping and mood state were re-assessed about 4 months after the events that had recruited the samples to the study. The measures of coping response were adapted from the coping domains of 'fighting spirit', 'helplessness', 'fatalism', 'avoidance' and 'anger/frustration' assessed in the Mental Adjustment to Cancer Scale. Details are provided of the construction of a summary measure of coping response based upon the above domains and of its relationship with follow-up mood state after allowance for mood levels at initial interview. |
8043616 | Partners in adversity. III. Mood status after the event. | This paper presents further results from a longitudinal study of three groups of married women undertaken in Edinburgh. Each group shared a common stressful experience. In the first group the marital partner had recently died; in the second the marital partner had recently experienced a myocardial infarction (MI) and the third group consisted of women recently entering a Women's Aid refuge. Interviews were completed shortly following the adverse experiences and where possible again about 3 months later. This report presents details of the (self-reported) mood status of the respondents at both assessment occasions in terms of the degree, form and change in symptomatic distress over what were equivalent time periods for the three groups. Mood status was determined on the basis of the conventionally scored 30-item GHQ (General Health Questionnaire) and according to a criterion-based scoring procedure. On this basis at initial interview almost 8 out of 10 of the widows were above the advised GHQ cut-point, almost 6 out of 10 of the refuge seekers and over 4 out of 10 of the coronary wives. At follow-up these proportions had almost halved for the widows and coronary wives but had changed very little for those few refuge-seekers successfully re-interviewed. According to a criterion-based measure at initial interview, the recent widows had an anxiety rate 5.2 times and a depression rate ten times that of a general population sample of women. Details of the changes in mood status amongst the groups over the follow-up are presented. |
8043615 | The costs of accommodation and care. Community provision for former long-stay psychiatric hospital patients. | The development of community services to replace two long-stay psychiatric hospitals in the North East Thames Health Authority region of the UK has been the subject of a research programme since 1985. The economic evaluation is conducted by the Personal Social Services Research Unit; research results relating to the first five cohorts of hospital leavers are reported in this paper. When followed up 1 year after discharge, almost half of the sample were living in highly supported residential care units, most of which were managed by district health authorities. More than 40 services provided outside the accommodation facility were used by clients and, although contact with certain professionals remained constant, some changes in service use over time were marked. The average total cost of community care for this group was 493 pounds per week (1992-93 prices), accommodation facility costs comprising approximately 85% of the total. In the new service configuration, district health authorities fund half of the costs of supporting the hospital leavers, 50% less than when they funded long-stay hospital placements. The rest of the funding burden is borne by a range of agencies, resulting in pressure on budgets and staff case loads. |
8043614 | Inhibition by glucose 6-phosphate of cyclic AMP-dependent protein kinase phosphorylation of glycogen synthase. | Cyclic AMP-dependent protein kinase phosphorylates and inactivates glycogen synthase. In the absence of cyclic AMP, glycogen synthase is able to partially activate cyclic AMP-dependent protein kinase, probably by inducing the dissociation of the catalytic and regulatory subunits. The activation of cyclic AMP-dependent protein kinase by glycogen synthase is greatly reduced by the addition of low, physiological concentrations of the allosteric activator of glycogen synthase, glucose 6-phosphate. This effect appears to be specific for both glycogen synthase as substrate of the kinase and for cyclic AMP-dependent protein kinase as glycogen synthase phosphorylating enzyme. The result is an apparent, although not real effect of glucose 6-phosphate as an inhibitor competing with cyclic AMP. The reported inhibition by insulin of the activity of cyclic AMP-dependent protein kinase in skeletal muscle may be explained by the increased intracellular levels of glucose 6-phosphate resulting from the action of the hormone on glucose transport. |
8043613 | Heparin-induced structural and functional alterations of bovine trypsin. | To investigate the mechanism whereby heparin can modulate the activity of serine proteinases, bovine trypsin was chosen as reference and treated with heparin at 10, 100 and 200 micrograms/ml, in buffer solvents, with and without incubation at 37 degrees C. Heparin caused rapid, buffer- and pH-dependent decrease in trypsin solubility due to the generation of insoluble fragments from proteinase. Desalting treatments variously restored solubility by removing insoluble material. UV absorption and fluorescence emission spectra revealed significant heparin-induced conformational alterations in the trypsin molecule, the maximal effect being apparent at a proteinase-to-heparin molar ratio ranging from 1.6 to 1.0. The involvement of the catalytic sites of trypsin by heparin was further confirmed by the significant reduction in the difference absorption spectra of proflavine. Both proteolytic and esterolytic activities of trypsin were shown to be markedly decreased by heparin, especially after 5 h incubation at 37 degrees C. However, when the proteolytic and esterolytic activities of trypsin were measured on fresh solutions not submitted to desalting treatments, variable activation instead of inhibition of both activities was observed in the presence of heparin, this effect waning spontaneously in time or after desalting treatment. The paradoxical increase in functional activities was not inhibited by soybean trypsin inhibitor and was accompanied by denaturation and fragmentation of the proteinase as demonstrated by spectroscopic analyses and SDS-PAGE of fresh solutions. The results obtained indicated that heparin causes a rapid, time- and temperature-dependent conformational alteration of trypsin with irreversible denaturation and degradation of the proteinase. The underlying mechanism appears to be heparin-catalyzed oxidative degradation of trypsin due to liberation of oxygen radicals which are also responsible for the temporary increase in catalytic functions. |
8043612 | Thermodynamic study of dihydrofolate reductase inhibitor selectivity. | The thermodynamic parameters of the binding of some folate analogues (methotrexate, trimetrexate and trimethoprim) to dihydrofolate reductases from different species have been measured with a flow microcalorimetric method at 37 degrees C. In the absence of NADPH, the three inhibitors exhibited a higher affinity for E. coli DHFR than for vertebrate DHFRs. This selectivity in favor of bacterial DHFR is entropy driven and is correlated with a weaker conformational change for bacterial DHFR than for vertebrate DHFRs, and with additional hydrophobic contacts, provided by this enzyme to the ligands. In presence of NADPH, as reported in the literature, trimetoprim shows a high selectivity in favor of bacterial DHFR, contrarily to methotrexate and trimetrexate, whose affinities are elevated and highly similar for mammalian and bacterial enzymes. The positive cooperative effect of NADPH, which has an enthalpic origin, fluctuates widely with inhibitor structure and with enzyme species. For trimethoprim, the cooperative effect is much more pronounced for bacterial DHFR than for vertebrate DHFRs. But the role of NADPH is not to induce a selectivity: it only increases the selectivity that trimethoprim already presented in absence of NADPH. Inversely, for methotrexate and trimetrexate, the cooperative effect is stronger for vertebrate enzymes than for the bacterial enzyme, and thus, NADPH cancels the selectivity the two antifolic compounds had, in the absence of NADPH, for the bacterial enzyme. |
8043610 | Tryptophan-19 of beta-lactoglobulin, the only residue completely conserved in the lipocalin superfamily, is not essential for binding retinol, but relevant to stabilizing bound retinol and maintaining its structure. | Residue 19 of tryptophan in bovine beta-lactoglobulin (beta-LG) is the only invariant residue throughout the lipocalin superfamily having two characteristic features: binding ability for small hydrophobic molecules and the unique beta-barrel three-dimensional structure. In this study, we investigated whether this strictly conserved Trp-19 of beta-LG would be indispensable for its structure and function such as maintaining the molecular structure and biological activity of beta-LG. Spectroscopic and enzymatic oxidation experiments on retinol bound to W19Y, in which Tyr was substituted for Trp-19, showed that Trp-19 was not critical for this binding, but was important for stably maintaining the environment surrounding retinol and the bound retinol. An using four anti-beta-LG monoclonal antibodies as probes, revealed a structural change in region 20-29, but not in the reverse region of Trp-19. A guanidine hydrochloride-induced unfolding study showed that the conformational stability of W19Y was greatly reduced by 6.9 kcal/mol compared to that of wild-type beta-LG. These facts indicated that Trp-19 is one of the important residues in correctly maintaining the local structure of beta-LG and stably retaining its overall structure, thereby conserving the bound retinol molecule. |
8043611 | Elastin synthesis is inhibited by angiotensin II but not by platelet-derived growth factor in arterial smooth muscle cells. | Effects of two major potent vasoconstrictors, angiotensin II and platelet-derived growth factor, on elastin expression in cultured chick embryonic arterial smooth muscle cells were studied. Platelet-derived growth factor exhibited no effect on elastin synthesis nor its mRNA level but stimulated (1.5-fold) cell proliferation slightly. Angiotensin II inhibited elastin synthesis dose- and time-dependent manner with a maximum suppression of sixty percent of control at a concentration of 10 microM for 18 h treatment. The suppression was accompanied with a comparable decrease in elastin mRNA level. The inhibition was blocked by addition of Sar1,Ala8-angiotensin II and 8-bromo-cGMP. It showed no effect on cell proliferation. Angiotensin II appears to inhibit elastin synthesis through the interaction with its receptor and the modulation of intracellular Ca2+ level. Thus angiotensin II, not platelet-derived growth factor, can exert a profound effect on the extracellular matrix composition in arterial walls, leading to an arterial change in hypertension or atherosclerosis. |
8043609 | Comparison of heme environment at the putative distal region of P-450s utilizing their external and internal nitrogenous ligand bound forms. | Thr-303 to Lys-mutated P-450 2E1, as well as Thr-301 to Lys-mutated P-450 2C2, had absorption spectra characteristic of a nitrogenous ligand-bound form of P-450, such as the pyridine complex of P-450 2E1; (i) in the ferric state, the red-shifted Soret band, compared with the typical low-spin type spectrum of P-450, and the more intense beta band than the alpha band and (ii) in the ferrous state, two Soret peaks at around 447 and 422 nm, the relative intensities of which depended on pH, indicating the existence of two interconvertible states. The equilibrium between the two states of the mutated P-450 2E1 appeared to be shifted toward the 422 nm state, compared with the mutated P-450 2C2. The corresponding mutant of P-450 2C14 had similar spectral properties to those of both mutated P-450s except that the shorter of the two Soret bands of its ferrous form was relatively broad and appeared at 418 nm. These findings suggest that the epsilon-amino-nitrogen of the Lys of the mutated P-450s is located in the appropriate position to occupy the sixth coordination position with the heme iron and spatial differences exist in the essentially conserved structure of the distal heme domain among the three ferrous Lys-mutated P-450s. |
8043608 | Significant contribution of arginine-112 and its positive charge of Pseudomonas putida cytochrome P-450cam in the electron transport from putidaredoxin. | Cytochrome P-450cam of Pseudomonas putida is a prototype of various eukaryotic cytochrome P-450 molecules. Arg-112 located on the surface of this protein is highly conserved among various other cytochromes P-450. In this study, we constructed mutant genes for P-450cam in which Arg-112 was replaced by Gln or Glu, expressed them in Escherichia coli and purified the mutant proteins. Their enzymic activities were analyzed in the reconstituted system to determine the function of Arg-112. Kd values for d-camphor of Arg112-Gln and Arg112-Glu were much the same as those of the wild-type enzyme, whereas Kd values for the oxidized form of putidaredoxin, which is an acidic protein and is the redox partner of P-450cam, were 240 and 530 microM, respectively. These values are 8 and 19 times larger than that of the wild-type enzyme (28 microM), thereby indicating lower affinities of the mutant enzymes for the oxidized putidaredoxin. Reaction rate constants for reduction by the reduced form of putidaredoxin, measured using the stopped flow method, were 45.5, 9.0 x 10(-3) and 9.0 x 10(-4) s-1 for the wild type, Arg112-Gln and Arg112-Glu, respectively. Thus, Arg-112 of P-450cam plays an important role in the interaction with putidaredoxin and in the high efficiency of the electron transfer; the positive charge of the residue seeming to contribute to the process. The yields in Escherichia coli, the heme contents in the purified fractions and heat stability of the mutant proteins were lower than those of the wild type enzyme, suggesting that Arg-112 of P-450cam is also important for stability of P-450cam. |
8043607 | Chromosomally encoded cephalosporin-hydrolyzing beta-lactamase of Proteus vulgaris RO104 belongs to Ambler's class A. | Proteus vulgaris RO104 strain produces a chromosomally encoded beta-lactamase that confers resistance to various beta-lactam antibiotics including methoxyimino third-generation cephalosporins. The beta-lactamase hydrolyzes first- and second-generation cephalosporins efficiently and cefotaxime to a lesser extent. Catalytic activity is inhibited by low concentrations of clavulanic acid and sulbactam. By its broad-spectrum substrate profile, beta-lactamase of Proteus vulgaris RO104 belongs to the group 2e defined by Bush. The protein purified to homogeneity by a four-step procedure was characterized by a pI of 8.31 and a specific activity of 1200 U/mg. The beta-lactamase was digested by trypsin, endoproteinase Asp-N and chymotrypsin. Amino-acid sequence determinations of the resulting peptides allowed the alignment of the 271 amino-acid residues of the protein which did not contain any cysteine residue. From amino-acid sequence comparisons, Proteus vulgaris RO104 beta-lactamase was found to share about 68% identity with the chromosomally mediated beta-lactamases of Klebsiella oxytoca D488 and E23004. Therefore, the cephalosporin-hydrolyzing beta-lactamase of Proteus vulgaris RO104 belongs to Ambler's class A. |
8043606 | Phenylalanine ammonia-lyase from cotton (Gossypium hirsutum) hypocotyls: properties of the enzyme induced by a Verticillium dahliae phytotoxin. | Phenylalanine ammonia-lyase (EC 4.3.1.5), induced by a Verticillium dahliae phytotoxin, has been purified to electrophoretic homogeneity from cotton hypocotyls by differential ammonium sulfate fractionation and hydrophobic interaction chromatography, with a yield of 52%. The enzyme is a tetramer with a molecular weight of 332,000 to 337,000. The isoelectric point is 4.6, and no isoforms were observed. The subunits of the enzyme are unstable and breaks down to fragments with M(r)'s of 69,000 and 49,500. The enzyme exhibited only activity with L-phenylalanine as substrate. Deamination was optimal at pH 8.9 and the activation energy was calculated as 100.6 kJ mol-1. Non-Michaelian kinetics were observed with a KmL = 10.0 microM and KmH = 75.0 microM describing the binding of the substrate to the enzyme. Negative cooperative interactions occurred between the substrate binding sites with a Hill coefficient of 0.87. The inhibitors AOPP (S)-2-amino-oxy-3-phenylpropanoic acid), APEP (R)-1-amino-2-phenylethylphosphonic acid) and 2-AIP (2-aminoindan-2-phosphonic acid) strongly inactivated the enzyme, as did various analogues of L-phenylalanine and t-cinnamate. The induced enzyme is also sensitive to inhibition by phenylpropanoid intermediates and precursors involved in lignification such as 4-hydroxycinnamate and 3,4-dihydroxycinnamate. |
8043605 | Cloning and sequence analysis of a hamster liver cDNA encoding a novel putative carboxylesterase. | A full-length cDNA encoding for a putative carboxylesterase was isolated from a hamster liver cDNA library. The cDNA consisting of 1911 base pairs contained an open reading frame of 1683 base pairs encoding for a polypeptide of 561 amino-acid residues, including 27 N-terminal amino-acid residues for signal peptide. The deduced amino-acid sequence of the cDNA is in 67% homology with the amino-acid sequence of rabbit form 2 carboxylesterase, which has not yet been cloned. It also had many structural features highly conserved among carboxylesterase isozymes. |
8043604 | Genetic evidence for an additional member of the metalloproteinase-like, disintegrin-like, cysteine-rich (MDC) family of mammalian proteins and its abundant expression in the testis. | Full-length clones have been isolated from a Macaca fascicularis cDNA library corresponding to a 2.65 kb mRNA present at high steady state levels in the testis. Sequence analysis suggests that the predicted translation product, tMDC II protein, represents a novel member of the metalloproteinase-like, disintegrin-like, cysteine-rich (MDC) family of mammalian proteins. |
8043603 | Identification of amino-acid residues linked to different properties of phosphoribosylpyrophosphate synthetase isoforms I and II. | The catalytic subunit of rat liver phosphoribosylpyrophosphate synthetase is composed of two isoforms, PRS I and PRS II. The amino-acid sequences differ only by 13 residues, out of which two Lys residues of PRS I at positions 4 and 152 give net additional positive charges to PRS I. Previous work has shown that PRS I is more sensitive to inhibition by ADP and GDP and more stable to heat treatment than is PRS II. To identify amino-acid residues responsible for the different properties, five chimeric enzymes between rat PRS I and PRS II and two mutated enzymes with a single point mutation at position 152 were constructed; these enzymes were produced in Escherichia coli. Changing Lys-4 of PRS I to Val, together with Ile-5 to Leu, completely abolished sensitivity to GDP inhibition of PRS I, indicating that Lys-4 in PRS I is critical for GDP inhibition. The substitutions at position 152 had little effect on GDP inhibition. Characterization of the chimeric enzymes revealed that residues between residues 54-110 and 229-317, namely, Val-55 and/or Ala-81, and Arg-242 and/or Cys-264 of PRS I also contribute to the strong GDP inhibition. Lys-4 was also important for the strong ADP inhibition of PRS I. Regarding the physical properties, chimeric enzymes bearing residues 12-53 of PRS I were stable at 49 degrees C and with digestion with papain and proteinase K. Our observations suggest that Lys-17, Ile-18, and/or Cys-40 of PRS I contribute to stability of the enzyme. |
8043602 | Primary structure and inhibitory properties of a proteinase inhibitor produced by Streptomyces cacaoi. | Protein proteinase inhibitors showing sequence homology with Streptomyces subtilisin inhibitor (SSI) have been found to be distributed widely in Streptomyces species, and accordingly have been named SSI-like (SIL) proteins. SIL1 from S. cacaoi was the first of these proteins to be isolated and to be given a serial number. To study the structure-function relationship of SIL proteins, we determined the primary structure of SIL1 and measured its inhibitory activities. It was found to be composed of 110 amino acids and to exist in dimer form. The amino-acid sequence of SIL1 was unique among other characterized SIL proteins in having a one-residue deletion in two regions and a three-residue insertion in the flexible loop region. Sequence comparison indicated that SIL1 was distantly related to other members of the SSI family, and that amino-acid replacements had occurred not only on the surface of the SIL1 molecule but also in the beta-sheet region. The reactive site of SIL1 was considered to be Arg70-Glu71 from sequence alignment with other SSI-family inhibitors. SIL1 inhibited subtilisin BPN' strongly with an inhibitor constant (Ki) of 2.8 x 10(-11) M, like other members of the SSI family possessing an Arg residue at the P1 site. In contrast, SIL1 exhibited weak inhibition toward trypsin with a Ki value of 5.5 x 10(-8) M, possibly as a consequence of insertion of the three residues in the flexible loop region near the reactive site. This contrast seems to be due to the difference in the subsite structure of the two proteinases. |
8043601 | The role of hydration in the hydrolysis of pyrophosphate. A Monte Carlo simulation with polarizable-type interaction potentials. | The exchange of energy in biochemical reactions involves, in a majority of cases, the hydrolysis of phosphoanhydrides (P-O-P). This discovery has lead to a long discussion about the origin of the high energy of such bonds, and to a proposal that hydration plays a major role in the energetics of the hydrolysis. This idea was supported by recent ab initio quantum mechanical calculations (Saint-Martin et al. (1991) Biochim. Biophys. Acta 1080, 205-214) that predicted the hydrolysis of pyrophosphate is exothermic in the gas phase. This exothermicity can account for only a half of the total energy release that one measures in aqueous solutions. Here we address the problem of hydration of the reactants and products of the pyrophosphate hydrolysis by means of Monte Carlo simulations, employing polarizable potentials whose parameters are fitted to energy surfaces computed at the SCF/6-31G** level of the theory. The present results show that the hydration enthalpies of the reactants and products contribute significantly to the total energy output of the pyrophosphate hydrolysis. The study predicts that both, the orthophosphate and the pyrophosphate, have hydration spheres with the water molecules acting as proton acceptors in the P-OH ... O(water) hydrogen bonds. These water molecules weakly repel the water molecules in the further hydration spheres. The perturbation of the structure of the solvent caused by the presence of the solute molecules is short ranged: after ca. 5 A from the P atoms, the energy and the structure of water correspond to bulk water. Due mainly to nonadditive effects, the molecular structure of the hydrated pyrophosphate is quite different from two fused structures of the hydrated orthophosphates. The hydration sphere of pyrophosphate is very loose and has a limited effect on the water network, whereas for orthophosphate it has a well developed shell structure. Hence, upon hydration there will be both a gain in hydration enthalpy and a gain in entropy because of distortion of the water molecular network. |
8043600 | Functional size of C-terminal protein carboxyl methyltransferase from kidney basolateral plasma membranes. | The functional sizes of the C-terminal isoprenylcysteine protein carboxyl methyltransferase (PCMT) from kidney cortex basolateral plasma membranes and yeast membranes have been estimated by the radiation inactivation and fragmentation method. Attempts to solubilize the methyltransferase with detergents were unsuccessful as they resulted in the irreversible denaturation of its enzymatic activity. The radiation inactivation sizes of the methyltransferases were 98 and 24 kDa for kidney and yeast, respectively. Kinetic experiments showed that irradiation affects the Vmax of the reaction but not the apparent Km for either S-adenosyl-L-methionine and N-acetyl farnesylcysteine. The functional size reported here for the kidney membrane is about 4-times larger than the size predicted for the Saccharomyces cerevisiae C-terminal PCMT deduced from the nucleotide sequence of its gene (28 kDa). These results suggest that mammalian methyltransferase has a functional size different from that of the yeast; tetramerization of monomers is one possible hypothesis for this difference. |
8043599 | Association and dissociation of protein disulfide isomerase. | Purified protein disulfide isomerase, homogeneous by SDS-PAGE, can be separated into two components by PAGE and by gel filtration. These two components, with the same amino-acid composition as well as N- and C-terminal sequences, are the tetramer and dimer of molecular weight 240 kDa and 120 kDa, respectively. The specific activity of the dimer is twice that of the tetramer. At 4 degrees C and pH 7.5 the purified dimer associates and the tetramer dissociates, both slowly and partially, to form a dimer-tetramer mixture. Treatment with dithiothreitol has only a minor effect on the dissociation of the tetramer indicating that the association is not through disulfide formation between the protomers. By prolonged treatment with 1% Triton X-100 or in strong salt solutions the tetramer dissociates to the dimer, but further dissociation to the monomer can only be effected in SDS or guanidine hydrochloride. These results suggest that apart from hydrogen bonds, hydrophobic forces and ionic interactions are mainly involved in the association of the protomers. |
8043598 | Topography of human placental 3 beta-hydroxysteroid dehydrogenase/delta 5-4 isomerase in microsomal membrane. A study using limited proteolysis and immunoblotting. | The membrane-bound enzyme 3 beta-hydroxysteroid dehydrogenase delta 5-4 isomerase (3 beta-HSD) catalyzes the formation of delta 4-3-ketosteroids from delta 5-3 beta-hydroxysteroids in placental, adrenal, testicular and ovarian tissues. In the present study was investigated the transverse-plane topography of 3 beta-HSD within the human placental microsome membranes employing immune-replica analysis in combination with surface specific proteolysis. The crucial domains of the enzyme for the dehydrogenase and isomerase reactions are inactivated by proteinase treatments under conditions where latency of hexose-6-phosphate dehydrogenase was 95%. The data indicate that these crucial domains face the cytosolic side of the endoplasmic reticulum membrane. Incubation of the intact microsomes with trypsin produces several immune reactive fragments ranging from 29 to 11 kDa in addition to 42 kDa native enzyme, one of them being shielded by the membrane structure and/or by other intrinsic and peripheral membrane proteins. Carboxypeptidase Y degraded the C terminus of the 42 kDa native 3 beta-HSD in intact and detergent-disrupted microsomes, preserving partially a fragment of 31 kDa. The results from the carboxypeptidase Y digestion indicate that the carboxy terminal end of the 3 beta-HSD enzyme is located on the cytoplasmic surface of the endoplasmic reticulum and that only a small fragment of approx. 11 kDa could be removed easily without affecting the enzyme activity. From these data and the predicted hydropathy analysis from the literature, we tried to assign a transmembrane arrangement to the human placental 3 beta-HSD. Our results support a topology model in which practically all the structural 3 beta-HSD enzyme is exposed to the cytoplasmic side of the membrane with one NH2-terminal-anchoring segment and all the 3 beta-HSD enzyme activity facing to the cytoplasmic side within the 31 kDa NH2-terminal peptide. |
8043597 | Biochemical thermodynamics. | Biochemists need two types of reaction equations, chemical equations in terms of species and biochemical equations in terms of reactants at specified pH and concentrations of free metal ions that are bound by reactant species. Both types of reaction equations have corresponding equilibrium constants, K for chemical reactions and K' for biochemical reactions. When the pH is specified you enter a whole new world of thermodynamics. There are new thermodynamic properties, new names (transformed thermodynamic properties), and new values, which are quite different, especially for the standard transformed Gibbs energy. This raises nomenclature problems because it is important to be able to distinguish between chemical equations and biochemical equations at a glance. It is also important to distinguish between the standard thermodynamic properties calculated from K and its temperature coefficient and the standard transformed thermodynamic properties calculated from K' and its temperature coefficient. |
8043596 | Complementation of Escherichia coli uncD mutant strains by a chimeric F1-beta subunit constructed from E. coli and spinach chloroplast F1-beta. | ATP-synthesizing F0F1-ATPases are complex enzymes consisting of at least eight different subunits. These subunits are conserved during evolution to a very variable degree ranging in pairwise comparison between, for example, Escherichia coli and spinach chloroplast from 20% to 66% identical residues. It was surprising to find that some of the less well conserved subunits like delta and epsilon could replace their E. coli counterparts, whereas the highly conserved beta subunit, which carries the active site, in the E. coli enzyme could not be substituted by spinach chloroplast beta (Lill et al. (1993) Biochim. Biophys. Acta 1144, 278-284). We constructed a chimeric F1-beta subunit consisting of spinach beta in which the 96 N-terminal amino acids were replaced by the respective residue sequence from E. coli beta. Whereas spinach beta did not complement E. coli uncD mutant strains, the chimeric beta subunit restored growth under conditions of oxidative phosphorylation. |
8043595 | Characterization of the oligomycin-sensitivity properties of the F1F0-ATPase in mitochondria from rats infected with the liver fluke Fasciola hepatica. | The F1F0-ATPase activity of liver mitochondria isolated from rats infected with Fasciola hepatica at 3 and 4 weeks post-infection showed a marked loss of sensitivity to oligomycin and to N,N'-dicyclohexylcarbodiimide. A loss of sensitivity to diethylstilbestrol was also demonstrated at 4 weeks post-infection. Recovery was apparent in most cases by 6 weeks post-infection. No significant difference in latent ATPase activity was observed between mitochondria from control and infected livers at any stage of the infection. The mitochondria from infected livers were therefore considered to have a full complement of the F1 moiety of the F1F0-ATPase complex. Purification of the mitochondrial ATPase from 4-week infected livers resulted in a very low yield of an oligomycin-insensitive complex. This was due to a failure to enrich specific activity during purification. The evidence presented indicates that infection with Fasciola hepatica gives rise to alterations in the function of the host liver mitochondrial ATPase, namely loss of inhibitor sensitivity and apparent structural alterations of the ATPase complex. |
8043594 | ATP synthesis kinetic properties of mitochondria isolated from the rat extensor digitorum longus muscle depleted of creatine with beta-guanidinopropionic acid. | A creatine analogue, beta-guanidinopropionic acid (beta-GPA), was administered in the food (1% w/w) of 8 male rats while 8 control rats received a standard diet. Mitochondrial oxidative capacity and kinetic parameters of mitochondrial ATP synthesis, apparent maximal ATP synthesis rate (Vmax) and apparent Michaelis constant for free ADP (Km), were investigated in the extensor digitorum longus (EDL) muscle. Mitochondrial ATP synthesis rate was measured by a bioluminescent method over a large range of ADP concentration (2-30 microM). As a result of the diet, Vmax was significantly increased (P < 0.05) while Km remained unchanged at around 20 microM. Citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase activities were significantly increased (both P < 0.05). Vmax was tightly correlated with CS activity (P < 0.001; r = 0.84). It was concluded that the increase in maximal mitochondrial ATP synthesis rate after beta-GPA feeding in EDL muscle was essentially due to a general increase in mitochondrial enzyme concentrations. |
8043593 | Effects of modulations of the energetic metabolism on the mortality of cultured cells. | Since cells are open systems which exchange material with their surroundings, they can be considered as open systems far from equilibrium and in this way, they follow the principles of thermodynamics of open systems. This approach stresses the fact that cells optimize their use of energy according to their functions. However, with time and/or under environmental challenges, cells can reorganize themselves at other lower levels of energy production and utilization (Toussaint et al. (1991) Mech. Ageing Dev. 61, 45-64). Considered as optimized systems, cells can adapt their behaviours according to the balance between, on one side, their energetic potential and the level of their defence systems, and on the other side, the intensity of the stress. Mainly three types of behaviour can be theoretically predicted. If the stresses are very low, the damages generated are instantaneously repaired and the cellular system remains at its steady state of energy production and utilization. If the stresses are of an intermediary intensity, it is predicted that the cell can leave its steady state of energy production and utilization and find a new one characterized by a lower level of entropy production and a higher level of errors. Third, if the stresses are of a very high intensity which can be cytotoxic, the level of the energetic potential of the cell is directly related to cell survival. We tested the latter prediction in the present work in two ways. First, the level of energy production was lowered by partially uncoupling the mitochondria. Then the effect of stresses under tert-butylhydroperoxide or ethanol was investigated in order to look for a synergistic effect on cell death with the mitochondria uncoupling. Secondly, the effect of a modification of the energetic sources during the stress was tested. Besides a protective effect found with specific defence systems, the presence of energetic metabolites such as D-glucose, pyruvate/malate, glutamate/malate, was tested and found to be protective. The effect of a stimulator of the energetic metabolism, naftidrofuryl oxalate, was also investigated and found protective. The experimental data provide good evidence that energetic factors can modulate the resistance of cells to various stresses. |
8043592 | Oxygen production and consumption by chloroplasts in situ and in vitro as studied with microscopic spin label probes. | A new spin-label oximetry approach able to measure the oxygen partial pressure in complex photosynthetic systems has been developed using bovine serum albumin (BSA)-coated light paraffin oil particles containing cholestane spin label (CSL). Paraffin oil particles protect the spin label against the action of chemically active metabolites. The amplitude of the electron paramagnetic resonance (EPR) signal from CSL measured at a saturating microwave power is sensitive to the concentration of oxygen. We demonstrate here the ability of this method to monitor the kinetics of light-induced oxygen production in situ, i.e., in the interior of a bean leaf. The oxygen release, observed during leaf illumination with continuous light, exhibits an overshoot that correlates with the well-known nonmonotonous behaviour of the Photosystem I reaction center, P700. Short-term illumination of isolated bean chloroplasts, suspended in the presence of the electron mediator methylviologen, induces a reversible uptake of oxygen. However, after prolonged illumination, chloroplasts lose their ability to regenerate oxygen in the dark. The exhaustion of oxygen (and oxygen active forms) is accompanied by the loss of CSL paramagnetism and the capacity to photooxidize P700. Comparison of the kinetics of P700 redox transients with oximetric data demonstrates that oxygen concentration is the essential factor controlling electron transport in leaves and isolated chloroplasts. |
8043590 | Energy-induced structural changes in NADH:Q oxidoreductase of the mitochondrial respiratory chain. | The reaction of coupled submitochondrial particles (SMP) with NADH was studied in the absence and presence of the uncoupler gramicidin, both in pre-steady-state and steady-state experiments. It was shown that the formation of ubisemiquinones associated with NADH:Q oxidoreductase is insensitive to uncouplers. It was found, however, that in the absence of gramicidin the ubisemiquinone showed a noticeably faster relaxation than in the presence of this uncoupler. During steady-state oxidation of NADH by coupled submitochondrial particles, the EPR signal of iron-sulphur cluster 2 of complex I, the cluster that is generally believed to be the electron donor for ubiquinone, showed some remarkable changes. Its gz line seemed to disappear from the spectrum, although the gxy line remained clearly present. Detailed EPR analysis indicated that (a component of) the gz line shifted to higher field. The temperature dependence of the EPR signal of cluster 2 was affected as well. In the presence of uncoupler the EPR properties of cluster 2 were indistinguishable from those in particles that showed no intrinsic coupling. These experiments strongly indicate that the coordination of cluster 2 is different in energized and non-energized SMP. The pre-steady-state reaction between these submitochondrial particles and NADH showed that the uncoupler-sensitive changes in both the ubisemiquinone and cluster 2 became effective between 9 ms and 30 ms. Similar changes were observed during succinate-driven reverse electron transfer. This report shows, for the first time, energy-induced structural changes in NADH:Q oxidoreductase. |
8043591 | Proton lateral conduction along a lipid monolayer spread on a physiological subphase. | A localized lateral proton pathway is present along the phospholipid polar heads and bound water molecules when the lipids are spread in monolayers at the air/water interface. Conduction can be detected on concentrated buffers as found under physiological conditions if the lateral proton gradient is large enough. The localized movement supports the occurrence of microlocalized proton circuits along a membrane and of lateral proton gradients. |
8043589 | Spectroscopic studies of phycobilisome subcore preparations lacking key core chromophores: assignment of excited state energies to the Lcm, beta 18 and alpha AP-B chromophores. | Chromophore absorption and emission characteristics of the alpha AP-B, beta 18 and Lcm (large core-membrane linker) chromopeptides within the phycobilisome core are investigated using genetically engineered strains of Synechococcus sp. PCC 7002. Steady-state and time-resolved emission were used to examine energy transfer in subcore preparations from the wild-type organism and two mutants. Low-temperature (77 K) emission spectra were also measured for intact phycobilisomes from the wild-type and five mutant strains. Mutants retaining either the alpha AP-B subunit or the unaltered Lcm chromophore resulted in only small changes in the low-temperature emission spectra, while retention of only the beta 18 subunit resulted in blue-shifted emission spectra. The Lcm chromophore has a room-temperature absorption maximum at 675 nm. In phycobilisomes at 77 K the alpha AP-B and Lcm chromophores emit at 682-683 nm, and they are the best candidates for long-wavelength emitters also at room temperature. Overlap of these emission spectra with the absorption of chlorophyll a in the associated thylakoid membrane plays a significant role in excitation transfer from the antenna complexes in cyanobacteria. |
8043588 | Mutation of tryptophan 128 in T4 endonuclease V does not affect glycosylase or abasic site lyase activity. | Mutation of various residues within the carboxy-terminal 11 amino acids of endonuclease V, an enzyme made up of 138 amino acids that initiates the repair of cyclobutane pyrimidine dimers in DNA, has demonstrated the importance of this region in dimer-specific binding. In a previous study, substitution of a serine residue for tryptophan 128 resulted in a protein with decreased abasic site lyase activity without a concomitant decrease in DNA glycosylase activity [Nakabeppu, Y., et al. (1982) J. Biol. Chem. 257, 2556-2562]. To assess the importance of the tryptophan at position 128, six mutants were constructed by site-directed mutagenesis, including W128Y, W128V, W128I, W128G, W128S, and W128T. Upon characterization, these six mutants were found qualitatively to complement the repair deficiency of ultraviolet (UV) light irradiated Escherichia coli cells (recA-, uvrA-) to levels comparable to that of wild-type endonuclease V. The activities of the mutant proteins were characterized using UV-irradiated plasmid DNA and oligonucleotides containing either a site-specific cyclobutane pyrimidine dimer or an abasic site. In all cases, the six mutants displayed glycosylase and abasic site lyase activities comparable to those of wild-type endonuclease V, indicating that Trp-128 is not crucial for dimer-specific binding or catalysis. |
8043587 | Molecular interactions of DNA-topoisomerase I and II inhibitor with DNA and topoisomerases and in ternary complexes: binding modes and biological effects for intoplicine derivatives. | Molecular interactions of intoplicine, dual DNA-topoisomerases (Topo) I and II inhibitor, with topoisomerases, plasmid DNA, in ternary cleavable complexes with enzymes and plasmid DNA, and in the reversed cleavable complexes were examined by means of surface-enhanced Raman scattering (SERS) and CD spectroscopy and by biochemical techniques. Detailed spectral analysis of intoplicine derivatives allowed us to assign SERS vibrational modes of chromophores and to propose the models for these complexes. Intoplicine was found to be able to interact specifically with the Topo II alone, but with Topo I only when in the presence of DNA. It shows at least two modes of binding to the DNA: the first was found to be dominant for its derivative 1c (most potent Topo I inhibitor), and the second was dominant for derivative 2a (most potent Topo II inhibitor). The possibility of forming these two types of complexes simultaneously is suggested to be one of the main factors enabling the drug to be a dual Topo I and Topo II inhibitor. The "deep intercalation mode" of the drug from the DNA minor groove with the long axis of the chromophore oriented roughly parallel to the dyad axis has been suggested to be responsible for induction of distortions of the DNA structure by the intercalating drug. Being involved in the formation of Topo I-mediated cleavable ternary complex, the molecules participating in the deep intercalation mode within the DNA do not change their molecular interactions as compared with their complex with the DNA alone. The stabilization of the Topo I-mediated cleavable complex was shown to be followed by the local denaturation of DNA in the AT-rich regions of the helix. When the ternary cleavable complex was reversed, the drug was shown to be in the complex with the plasmid. The "outside binding mode" from the DNA major groove via the hydroxyl group of the A-ring of the chromophore has been suggested to be responsible for Topo II inhibition. These molecules did not induce significant distortions of the DNA structure. Being involved in the formation of Topo II-mediated cleavable ternary complex, the drug changed its molecular interactions as compared with the complex with DNA alone.(ABSTRACT TRUNCATED AT 400 WORDS) |
8043586 | Mutagenesis at a site-specifically modified NarI sequence by acetylated and deacetylated aminofluorene adducts. | A hotspot for mutagenesis by N-acetyl-2-aminofluorene (AAF) was site-specifically modified with 2-aminofluorene (AF) and AAF adducts, and the mutation frequencies and specificities were determined and compared. Previous work has shown that the presence of an AAF adduct in a NarI sequence (GGCGCC) results a high mutation frequency for a CG double base pair deletion. In the present study, an M13 derivative was constructed that contained a NarI recognition sequence in the beta-galactosidase gene of bacteriophage M13mp9. This derivative was site-specifically modified with either an AF or an AAF adduct, the products were characterized, and these templates were then transformed into Escherichia coli wild-type strain JM103 or uvrA strain SMH12. The levels and mutation spectra were determined either with or without SOS induction. It was found that, with SOS functions induced, the measured mutation frequencies were substantially higher in all cases. More importantly, the types of mutations induced by the AAF and AF adducts were very different: AAF adducts induced almost exclusively CG double base deletion mutations, whereas AF adducts gave rise specifically to base-substitution mutations. The AF-derived mutation spectrum included both G to T and G to A mutations. The results are discussed in light of the current views on the relationship between the DNA structure and mutagenesis. |
8043585 | Ligand interaction between urokinase-type plasminogen activator and its receptor probed with 8-anilino-1-naphthalenesulfonate. Evidence for a hydrophobic binding site exposed only on the intact receptor. | The cellular receptor for urokinase-type plasminogen activator (uPAR) is a glycolipid-anchored membrane protein thought to play a primary role in the generation of pericellular proteolytic activity, and to be involved in cancer cell invasion and metastasis. This protein is composed of three homologous domains, the NH2-terminal of which is involved in the high-affinity binding (Kd approximately 0.1-1.0 nM) to the epidermal growth factor-like module of urokinase-type plasminogen activator (uPA). Here we report that intact uPAR binds the low molecular weight fluorophore 8-anilino-1-naphthalenesulfonate (ANS) to form a 1:1 stoichiometric complex and that the resulting enhancement of the ANS fluorescence probes the functional state of uPAR as judged by several independent criteria. First, the uPAR-mediated increase in ANS fluorescence can be titrated by uPA as well as by its receptor binding derivatives (the amino-terminal fragment and the growth factor-like module). Second, an anti-uPAR monoclonal antibody, capable of preventing uPA binding, can also titrate the uPAR-dependent ANS fluorescence whereas other antibodies not interfering with uPA binding are unable to exert this effect. Third, the dissociation profile of uPA-uPAR complexes as a function of increasing concentrations of guanidine hydrochloride closely parallels the loss of the ANS binding site in uPAR. Finally, liberation of the NH2-terminal domain from uPAR by limited chymotrypsin cleavage after Tyr87 leads to a loss of both enhanced ANS fluorescence and high-affinity uPA binding.(ABSTRACT TRUNCATED AT 250 WORDS) |
8043584 | Gaussian decomposition of absorption and linear dichroism spectra of outer antenna complexes of photosystem II. | Room temperature and 10 K absorption and linear dichroism spectra of the chlorophyll-protein complexes comprising the outer antenna of PSII (LHCII, CP29, CP26, CP24) have been analyzed in terms of a linear combination of asymmetric Gaussian bands. The results demonstrate the following: (a) The absorption and linear dichroism spectra of each sample can be described by nearly the same set of Gaussian bands at room temperature and 10 K. (b) The relative distributions of the transition moments of the major red-absorbing spectral forms seem to be similar in all four outer antenna chlorophyll-protein complexes at room temperature, with the 684-nm band being oriented closest to the particle plane at room temperature and the 677- and 669-nm bands being tilted at progressively greater angles out of the particle plane. The shorter wavelength transitions seem to be oriented close to the magic angle, but interpretation is complicated in this spectral region due to the low linear dichroism values and by overlap with vibrational bands. (c) The 684-nm band, detected in room temperature absorption and linear dichroism spectra of all complexes, vanishes at 10 K. |
8043583 | Identification of Trp-371 as the main site of specific photoaffinity labeling of corticosteroid binding globulin using delta 6 derivatives of cortisol, corticosterone, and progesterone as unsubstituted photoreagents. | Immunopurified human corticosteroid binding globulin (CBG) was photolabeled with delta 6-[3H]cortisol, delta 6-[4-14C]cortisol, delta 6-[3H]corticosterone, and delta 6-[3H]progesterone. The maximal levels of specific incorporation, as estimated with tritiated photoreagents, were 0.21, 0.14, and 0.08 mol of label/mol of CBG, respectively. Tryptic cleavage of photolabeled CBG gave in all cases a major radioactive peptide that was no longer detectable when a 100-fold molar excess of cortisol was added to the photoreagents. Edman sequencing of tryptic peptides photolabeled with delta 6-[3H]cortisol or delta 6-[3H]corticosterone showed that these peptides correspond to residues 357-378 of the human CBG sequence. The major peak of radioactivity of these peptides was eluted at the 15th cycle (Trp-371). The radioactive tryptic peptides photolabeled with the four steroid photoreagents were subcleaved with alpha-chymotrypsin. The major part of radioactivity was recovered in the T-[*X]-S-S-L-F hexapeptide 370-375 (major peptide) and in the D-H-F-T-[*X]-S-S-L-F nonapeptide 367-375, at the second and fifth Edman cycles, respectively, whereas no PTH derivative could be identified at these cycles, thus suggesting Trp-371 as the main site of photolabeling for all tested photoreagents. Mass spectrometry of tryptic peptides photolabeled with delta 6-[3H]cortisol and delta 6-[3H]corticosterone and of chymotryptic peptides photolabeled with delta 6-[3H]cortisol, delta 6-[3H]corticosterone, and delta 6-[3H]progesterone showed molecular masses corresponding to the addition of delta 6-steroid photoreagents to the peptide. |
8043582 | Involvement of serine 74 in the enzyme-coenzyme interaction of rat liver mitochondrial aldehyde dehydrogenase. | It has been suggested that the active site nucleophile in sheep liver aldehyde dehydrogenase was not a cysteine residue but was a serine located at position 74 [Loomes, K. M., Midwinter, G. G., Blackwell, L. F., & Buckley, P. D. (1990) Biochemistry 29, 2070-2080]. This enzyme form has not yet been cloned and expressed, but since the rat liver mitochondrial enzyme has been and shares 70% sequence homology with other cytosolic aldehyde dehydrogenases, the residue in the rat enzyme was converted into an alanine to test for the necessity of a hydroxyl group at that position. The recombinantly expressed mutant enzyme possessed 10% catalytic activity, but the Km for NAD increased from 10 to 1900 microM while the Kms for various aldehydes were unchanged. Kinetic analysis revealed that the dissociation constant for NAD also increased in the mutant as did k1, the on velocity for NAD binding. The mutant enzyme bound poorly to an AMP-Sepharose column and did not interact as well with NADH, as determined by fluorescence enhancement binding studies, or with ADP-ribose, a competitive inhibitor. Pulse-chase analysis showed that the mutant was as stable as was the recombinantly expressed native enzyme. It was less stable to heat denaturation at 50 degrees C (half-life of 1 min compared to 4). Converting the alanine to a cysteine or a threonine did not restore native-like properties of the enzyme. These mutants had kinetic properties very similar to those of the alanine mutant.(ABSTRACT TRUNCATED AT 250 WORDS) |
8043581 | Phosphorylation of the 61-kDa calmodulin-stimulated cyclic nucleotide phosphodiesterase at serine 120 reduces its affinity for calmodulin. | Phosphorylation of the 61-kDa isoform of bovine calmodulin (CaM)-stimulated cyclic nucleotide phosphodiesterase (CaM-PDE) by the catalytic subunit of cyclic AMP-dependent protein kinase A (PKA) results in a decrease in the affinity of the enzyme for calmodulin [Sharma, R. K., & Wang, J. H. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 2603-2607]. In the present study, purified 61-kDa CaM-PDE was phosphorylated in the presence of [gamma-32P]ATP and cleaved with a Lys-C endoproteinase. The resultant phosphopeptides were resolved by reverse-phase HPLC and analyzed by electrospray mass spectrometry and Edman sequencing. Serine residues 120 and 138 were identified as the principal sites of phosphorylation. A cDNA encoding the 61-kDa CaM-PDE [Sonnenburg, W. K., Seger, D., & Beavo, J. A. (1993) J. Biol. Chem. 268, 645-652] was used to generate point mutants in which either or both of these serines were replaced with alanine. The mutants were expressed in COS-7 cells, purified, and phosphorylated. Phosphorylation of the mutant Ser 138-->Ala resulted in a decrease in affinity for CaM that was comparable to that seen with the wild-type enzyme. In contrast, phosphorylation of the mutant Ser 120-->Ala had virtually no effect on CaM affinity. We conclude that phosphorylation of serine 120 by PKA is responsible for the reduction in affinity of the 61-kDa CaM-PDE for CaM. |
8043580 | Ca(2+)-dependent binding of endonexin (annexin IV) to membranes: analysis of the effects of membrane lipid composition and development of a predictive model for the binding interaction. | Endonexin (annexin IV) is a member of the annexin family of homologous proteins that bind membranes and aggregate vesicles in a calcium-dependent fashion. This study examines the lipid modulation and mechanism of the binding of endonexin to membranes using a fluorescence energy transfer assay to measure bovine endonexin binding to well-defined large unilamellar vesicles. The calcium sensitivity for endonexin-membrane binding is observed to be highly dependent on the types of membrane lipids present. As with most annexins, negatively charged lipids best promote endonexin binding to phosphatidylcholine (PC) containing membranes. However, a comparison of 11 different types of lipids reveals that other factors such as the type of ion contributing the charge and head-group size are also important. The concentrations of calcium required for half-maximal binding of endonexin to PC vesicles containing 30% phosphatidylserine (PS) or 30% phosphatidylinositol (PI), both lipids with net charge-1, are 48 +/- 6 and 114 +/- 19 microM, respectively, while half-maximal binding to 30% phosphatidylinositol bisphosphate (PIP2), with a greater net charge of -3 to -5, occurs at 65 microM calcium, similar to the calcium requirement for binding to PS. The apparent affinities of endonexin for seven different types of lipids parallel those reported for annexin V [Andree, H. A. M., Reutelingsperger, C. P. M., Hauptmann, R., Hemker, H. C., Hermans, W. T., & Willems, G. M. (1990) J. Biol. Chem. 265, 4923-4928], except for a greater preference of endonexin for membranes containing phosphatidic acid. Mixing PS and phosphatidylethanolamine (PE) or PS and PI in the same PC vesicle synergistically enhances endonexin-membrane binding, indicating that even lipids with no net charge such as PE may dramatically affect endonexin binding to mixed-lipid membranes. The maximum amount of endonexin able to bind to PS/PC vesicles at 1 mM calcium increases with mole % PS. A simple and general model that treats protein-membrane binding as a two-step process, with adsorption to a membrane surface followed by interaction with specific lipid molecules [Lentz, B. R., & Hermans, J. (1989) Biochemistry 28, 7459-7461], is extended to include the coupled binding of calcium with binding of specific lipid molecules. This extended model accurately predicts trends observed when protein and calcium titrations of endonexin binding to PS/PC vesicles are performed under a wide variety of conditions and suggests that 3-5 calcium ions and 9-18 PS molecules participate in each endonexin-membrane complex.(ABSTRACT TRUNCATED AT 400 WORDS) |
8043579 | Association of Hsp90 with cellular Src-family kinases in a cell-free system correlates with altered kinase structure and function. | Following synthesis in the cytoplasm, the transforming proteins encoded by the retroviral oncogenes src, yes, fps, fes, and fgr form complexes with hsp90 and the hsp90 cohort p50. These cytoplasmic complexes are intermediates in the production of the mature membrane-associated kinase. However, soluble complexes between the nascent cellular homologs of these proteins and hsp90-p50 have not been readily detected [Brugge, J.S. (1986) Curr. Top. Microbiol. Immunol. 123, 1-22 and references therein]. In this paper, we have utilized protein synthesis in reticulocyte lysate to determine whether three cellular members of the src family of tyrosine kinases, myeloid-specific p59fgr, B cell-specific p59fgr, and p56lck, form complexes with hsp90. Following their synthesis, fast- and slow-sedimenting forms of these proteins can be separated on glycerol gradients. Anti-hsp90 monoclonal antibodies co-immunoadsorb the fast-sedimenting, but not the slow-sedimenting, forms of these kinases from gradient fractions. These hsp90 complexes can be detected in the complete absence of detergent. Conversely, an unrelated protein, firefly luciferase, does not form stable complexes with hsp90 following synthesis in reticulocyte lysate. Anti-p56lck antibodies specifically co-immunoadsorb hsp90 from protein synthesis reactions programmed with lckRNA. The fast-sedimenting, complex-bound form of p56lck is deficient in autophosphorylation activity and phosphorylates an exogenous substrate, acid-treated enolase, less efficiently than does the monomeric form. Fast-sedimenting p56lck is hypersentitive to limited proteolysis by chymotrypsin.(ABSTRACT TRUNCATED AT 250 WORDS) |
8043578 | Nucleoside modifications stabilize Mg2+ binding in Escherichia coli tRNA(Val): an imino proton NMR investigation. | The structures of in vitro transcribed Escherichia coli tRNA(Val), which lacks base modifications, and the native tRNA, which contains them, are very similar in the presence of excess Mg2+ (Kintanar, Yue, and Horowitz, unpublished results). To further probe the effects of base modifications on the structure of tRNA, the Mg2+ ion dependence of the downfield region of the 1H NMR spectrum of in vitro transcribed E. coli tRNA(Val) in aqueous phosphate buffer was investigated. The spectra indicate a remarkable conformational change in unmodified E. coli tRNA(Val) coincident with binding or release of Mg2+. Assignment of the imino proton resonances in the low Mg2+ form of the tRNA transcript allows a detailed description of the conformational change. There is near total disruption of the D stem and tertiary interactions in the absence of bound Mg2+. A new strong interaction between the U67-A6 base pair and the G50-U64 wobble pair is observed, indicating a substantial structural rearrangement at the junction of the acceptor and T stems. The binding constants of the strong Mg2+ binding sites in the D loop and near the D stem in unmodified tRNA(Val) are at least 2 orders of magnitude less than in tRNAVal containing base modifications. The metal ion binding site in the anticodon loop is somewhat stronger than metal ion binding sites in the D loop and stem in unmodified tRNA(Val), but it is still weaker than all strong Mg2+ binding sites in native tRNA(Val). Thus, one role of the base modifications found in tRNA is to stabilize or strengthen the Mg2+ binding sites.(ABSTRACT TRUNCATED AT 250 WORDS) |
8043577 | Solution conformation of an atrial natriuretic peptide variant selective for the type A receptor. | Two-dimensional NMR spectroscopy has been used to characterize the solution conformation of an atrial natriuretic peptide (ANP) variant which is selective for the human natriuretic peptide receptor A (NPR-A) relative to receptor C (NPR-C). The ANP mutant, containing six substitutions, has reduced flexibility in aqueous solution relative to wild-type ANP and allows the observation of sufficient NOE connectivities for structure determination by distance geometry and restrained molecular dynamics calculations. The solution conformation is reasonably well defined, having an average backbone atom rms deviation from the average coordinates of approximately 1.1 A for residues 7-27. The structure is consistent with available functional data and shows a spatial separation between known receptor binding determinants and residues found to be outside the hormone-receptor interface. |
8043576 | Electrostatic potential surface analysis of the transition state for AMP nucleosidase and for formycin 5'-phosphate, a transition-state inhibitor. | AMP nucleosidase hydrolyzes the N-glycosidic bond of AMP to yield adenine and ribose 5-phosphate. Kinetic isotope effects have been used to establish an experimentally based transition-state structure for the native enzyme and a Vmax mutant [Mentch, F., Parkin, D. W., & Schramm, V. L. (1987) Biochemistry 26, 921-930; Parkin, D. W., Mentch, F., Banks, G. A., Horenstein, B. A., & Schramm, V. L. (1991) Biochemistry 30, 4586-4594]. The transition states are characterized by weak reaction coordinate bonds to C1' and substantial carbocation character in the ribose ring. The N9-C1' bond to the leaving group is nearly broken and the adenine ring is protonated at the transition state. Formycin 5'-phosphate and other purine nucleoside 5'-phosphate analogues with syn-glycosyl torsion angles bind better than substrate, supporting a syn configuration in the enzyme-substrate complex and presumably in the transition state [Giranda, V. L., Berman, H. M., & Schramm, V. L. (1988) Biochemistry 27, 5813-5818]. Access to a geometric model of the transition state permits the analysis of its molecular electrostatic potential surface as enforced by the enzyme. Comparison of the molecular electrostatic potential surfaces for AMP, formycin 5'-phosphate, and the transition state reveals a striking similarity in the surface charges of formycin 5'-phosphate and the transition state. The enzyme-stabilized transition state for AMP hydrolysis is characterized by new positive electrostatic potential in the adenine ring as a result of protonation by the enzyme. This is closely matched by the protonated pyrazole ring of formycin 5'-phosphate. The molecular electrostatic potential surfaces of formycin 5'-phosphate and the transition state for AMP are similar and are likely to be a factor in the Km/Ki value of > 10(3) for formycin 5'-phosphate as a transition-state inhibitor of AMP nucleosidase. |
8043575 | Protein-protein recognition: crystal structural analysis of a barnase-barstar complex at 2.0-A resolution. | We have solved, refined, and analyzed the 2.0-å resolution crystal structure of a 1:1 complex between the bacterial ribonuclease, barnase, and a Cys-->Ala(40,82) double mutant of its intracellular polypeptide inhibitor, barstar. Barstar inhibits barnase by sterically blocking the active site with a helix and adjacent loop segment. Almost half of the 14 hydrogen bonds between barnase and barstar involve two charged residues, and a third involve one charged partner. The electrostatic contribution to the overall binding energy is considerably greater than for other protein-protein interactions. Consequently, the very high rate constant for the barnase-barstar association (10(8) s-1 M-1) is most likely due to electrostatic steering effects. The barnase active-site residue His102 is located in a pocket on the surface of barstar, and its hydrogen bonds with Asp39 and Gly31 residues of barstar are directly responsible for the pH dependence of barnase-barstar binding. There is a high degree of complementarity both of the shape and of the charge of the interacting surfaces, but neither is perfect. The surface complementarity is slightly poorer than in protease-inhibitor complexes but a little better than in antibody-antigen interactions. However, since the burial of solvent in the barnase-barstar interface improves the fit significantly by filling in the majority of gaps, as well as stabilizing unfavorable electrostatic interactions, its role seems to be more important than in other protein-protein complexes. The electrostatic interactions between barnase and barstar are very similar to those between barnase and the tetranucleotide d(CGAC). In the barnase-barstar complex, the two phosphate-binding sites in the barnase active site are occupied by Asp39 and Gly43 of barstar. However, barstar has no equivalent for a guanine base of an RNA substrate, resulting in the occupation of the guanine recognition site in the barnase-barstar complex by nine ordered water molecules. Upon barnase-barstar binding, entropy losses resulting from the immobilization of segments of the protein chain and the energetic costs of conformational changes are minimized due to the essentially preformed active site of barnase. However, a certain degree of flexibility within the barnase active site is required to allow for the structural differences between barnase-barstar binding and barnase-RNA binding. A comparison between the bound and the free barstar structure shows that the overall structural response to barnase-binding is significant. This response can be best described as outwardly oriented, rigid-body movements of the four alpha-helices of barstar, resulting in the structure of bound barstar being somewhat expanded. |
8043574 | Three-dimensional solution structure and 13C assignments of barstar using nuclear magnetic resonance spectroscopy. | We present the high-resolution solution structure and 13C assignments of wild-type barstar, an 89 amino acid residue polypeptide inhibitor of barnase, derived from heteronuclear NMR techniques. These were obtained from measurements on unlabeled, uniformly 15N- and 13C/15N-labeled, and 10% 13C-labeled barstar samples that have both cysteines (at positions 40 and 82) fully reduced. In total, 30 structures were calculated by hybrid distance geometry-dynamical simulated annealing calculations. The atomic rms distribution about the mean coordinate positions is 0.42 A for all backbone atoms and 0.90 A for all atoms. The structure is composed of three parallel alpha-helices packed against a three-stranded parallel beta-sheet. A more poorly defined helix links the second beta-strand and the third major alpha-helix. The loop involved in binding barnase is extremely well defined and held rigidly by interactions from the main body of the protein to both ends and the middle of the loop. This structure will be used to aid protein engineering studies currently taking place on the free and bound states of barstar and barnase. |
8043573 | Sequential proton resonance assignments and metal cluster topology of lobster metallothionein-1. | NMR studies of 111Cd6-MT 1 from lobster have been conducted to determine coordination structure of Cd-thiolate binding in the protein. Sequential proton resonance assignments were made using standard two-dimensional 1H NMR methods. Two-dimensional 1H-111Cd HMQC experiments were then carried out to determine the cadmium-cysteine connectivities in the protein. With this information, it was established that the six Cd ions exist in two different Cd3S9 clusters, each involving three bridging and six terminal thiolate ligands. Sequential cysteines in the sequence provide the sulfhydryl ligands for each cluster and do not overlap, as has been found in mammalian metallothionein. Comparison of the N-terminal, Cd3S9 B-type cluster of lobster MT 1 with the Cd3S9 cluster from rabbit MT 2 shows that while eight of the nine cysteine residues occupy homologous positions in their sequences, three of the 12 Cd-thiolate connectivities are different. Similarly, the C-terminal B-cluster of lobster MT 1 was compared with the Cd4S11 cluster of mammalian MT 2, excluding the two terminal cysteine sulfhydryl groups that convert this cluster from A- to B-type. As above, eight of nine cysteine positions are identical, yet five of 12 Cd-sulfhydryl connections are different. These differences are expanded when the role of each cysteine as bridging or terminal ligands in the clusters is considered. |
8043572 | Solid state 13C and 15N NMR investigations of the N intermediate of bacteriorhodopsin. | Previous solid state 13C NMR studies of bacteriorhodopsin (bR) have inferred the C = N configuration and the protonation state of the retinal-lysine Schiff base (SB) linkage from the [13-13C]-retinal, [14-13C]retinal, and [epsilon-13C]lysine-216 chemical shifts in the bR555, bR568, and M412 states. Here we determine the C = N configuration and the protonation state of the N photointermediate that is cryotrapped along with the M photointermediate at high salt concentrations (0.1 M NaCl) and high pH (10.0). We obtained 13C and 15N SSN MR spectra of [epsilon-15N]lysine bR and [12-13C]- and [13-13C]retinal bR for samples illuminated under the above conditions. Two species are observed, both of which decay to bR568 upon warming. One species has chemical shifts identical to those obtained previously for M thermally trapped in guanidine.HCl at high pH (Smith et al., 1989a; Farrar et al., 1993). In the other species, the [epsilon-15N]lysine and 13-13C chemical shifts indicate that the SB is protonated, the 12-13C shift indicates a 13 = 14 cis configuration, and the previously published [14-13C]- and [epsilon-13C]lysine shifts indicate a C = N anti configuration. These results are consistent with other studies of the N photointermediate. |
8043571 | Health and safety at work in orthodontic practice--Part II. | On April 1st, 1992 practice inspections came into force and the remit of the inspector takes into consideration not only whether the practice is a safe place in which patients may be treated, but also whether the environment is safe for staff to work in. Gone are the days therefore when one could ignore health and safety at work, for to do so could result in a new practice not being added to a FHSA list or at the worst an existing practice made to close down! |
8043568 | Bite-opening mechanics as applied in the Begg Technique. | In the Begg Technique, factors controlling the anterior intrusive force provided by the archwire have yet to be fully clarified. The rationale for bite opening with very light forces, the effect of Class II elastics on intrusive force magnitude and the intrinsic quality of 'Australian' wire in bite opening are examined in this paper. A formula is presented which allows the intrusive force that archwires exert in different individuals to be predicted. The values derived from the formula were compared with case model measurements. It was found that the intrusive force of the archwire was affected by the length of the individual dental arch. The magnitude of this intrusive force was seen to increase gradually during the period of bite opening and appeared to be related to the use of Class II elastics. The study revealed factors which affected the magnitude of the intrusive force. |
8043567 | A comparison of the Index of Orthodontic Treatment Need applied clinically and to diagnostic records. | The Index of Orthodontic Treatment Need was applied clinically to a group of patients and later to study models and photographs taken at that same visit. Examiner reliability and agreement between the information obtained clinically and from diagnostic models was high. There was however, poor agreement for the Aesthetic component scored from photographs, when compared with scores recorded clinically or from models. |
8043566 | Use of the Index of Orthodontic Treatment Need (IOTN) in assessing the need for orthodontic treatment pre- and post-appliance therapy. | The Index of Orthodontic Treatment Need (IOTN) was used to assess the need for orthodontic treatment before and after treatment, on a systematic sample of 1225 cases. On the whole, full upper and lower fixed appliances brought about a greater improvement in Aesthetics and Dental Health Components compared to other appliance techniques, and were less likely to make the occlusion worse. It was found that certain occlusal traits were more likely to be successfully treated than others. A common problem resulting from treatment was the development of a cross-bite. |
8043565 | The palatal canine and the adjacent lateral incisor: a study of a west of Scotland population. | The hypothesis that palatally-displaced canines are associated with smaller than average lateral incisors or with congenital absence of adjacent lateral incisors was tested on a West of Scotland population. A retrospective study of the records of orthodontic patients attending Glasgow Dental Hospital was carried out. One-hundred-and-eighty-two subjects with palatally displaced canines were identified. The tooth length of lateral and central incisors was measured on radiographs and the crown widths of lateral incisors were measured on study casts. One-hundred-and-six extracted maxillary lateral incisors were examined to allow more accurate measurement of crown width and root length than was possible from radiographs. An association was sought between the size of the lateral incisor or its absence, the position of the adjacent maxillary canine, and between crown size and root length of the lateral incisor. The conclusions supported the hypothesis that there is a weak association between palatally displaced maxillary canines and lateral incisors of smaller than average crown width. There was weak support for the association between palatal canines and absence of the adjacent lateral incisor. There was no correlation between lateral incisor crown width and root length. |
8043564 | The finite element analysis of stress in the periodontal ligament when subject to vertical orthodontic forces. | In the past, vertical intrusive movement of teeth has been considered difficult and most routine clinical vertical movement of teeth has been confined to extrusion. It has been suggested that attempts at intrusion may result in an increased incidence of root resorption and also in occasional devitalization. The displacement and resulting stress fields associated with such treatment can be successfully studied using the finite element method. In the case being considered initial movements are known to be small; therefore, the assumption in the study that the material behaves linear-elastically is considered to be reasonable. This study of vertical tooth movement demonstrated that the maximum cervical margin stress in the periodontal ligament was 0.0046 N/mm2, whilst the highest apical stress was 0.00205 N/mm2 when intrusive and extrusive forces of 1 Newton were applied to the buccal surface of the crown of a tooth model. These stresses were evaluated in the light of previous studies and found to be within the suggested clinical optimum level. However, the periodontal stress distribution following orthodontic loading within this three-dimensional finite element model was found to be highly complex. |
8043563 | Orthodontic treatment and isolated gingival recession: a review. | Isolated gingival recession may occur in as many as 30 per cent of adolescents, and lead to problems of dentine hypersensitivity, root caries, and gingival inflammation in adult life. This review discusses the prevalence and aetiology of isolated recession, with particular reference to the implications for orthodontic treatment. Consideration is also given to the differing philosophies for management. |
8043562 | Facial aesthetics following edgewise and Fränkel appliance therapy: the application of Chernoff faces. | This study investigates an application of the graphical technique of multivariate data description, 'Chernoff faces', to orthodontics. This method of pictorial presentation allows the simultaneous examination of several measurements in a single figure. Each variable is represented by a scaled feature of the human face: the size and position of the ears, eyes, eyebrows, nose, and mouth, as well as the face itself, are used to display data in a diagrammatic form. Using this method, the individual post-treatment results of 62 severe Class II division 1 cases treated by either Fränkel or Edgewise appliance therapy were compared. Nine cephalometric variables were chosen, describing the profile and the antero-posterior positions of the lower jaw and teeth, and stylized cartoon faces drawn for each child. These were compared with a control face prepared from untreated children of the same sex and age. Overall, children treated with Fränkel appliances showed a more normal relationship of the lips to Ricketts' aesthetic line and a greater prominence of the lower face. This difference between the two groups was most marked in the soft tissues. In a few cases, however, the appearance of the Edgewise treated children was indistinguishable from that of the controls. It is concluded that Chernoff faces, by portraying several pertinent aspects of data simultaneously, may be a useful adjunct to the presentation of orthodontic findings. |
8043561 | A comparative study of the shear bond strengths of four different crystal growth solutions. | Previously, solutions based on polyacrylic acid have been found to initiate crystal growth on the enamel surface. Such crystals have been proposed as being suitable for the attachment of orthodontic brackets via a conventional composite interface, the advantages being improved clean-up characteristics and reduced damage to the enamel. In order to try and improve the reliability of the technique this base solution has been modified by the authors, by the addition of various ionic salts. The strength of the resultant bond was assessed for the base solution of 50 per cent polyacrylic acid and concentrated sulphuric, and for three more solutions modified by the addition of the sulphates of lithium, magnesium, and potassium, respectively. A standard acid/etch method of bracket attachment was also included for the purposes of comparison. The bond strength of each material was assessed by shear testing, performed on human extracted premolar teeth to a standard method. As might have been expected the acid/etch system proved to be the strongest method of bonding brackets. Amongst the crystal solutions, the addition of lithium sulphate provided the highest mean shear strength at 80 per cent of that for acid etch. Therefore, this latter solution provides the most potential for development in the future. |
8043560 | Microbial growth on the surfaces of various orthodontic bonding cements. | An experimental technique was developed to examine the adhesion of a strain of Streptococcus mutans to the surface of discs of selected orthodontic bonding composites and a glass ionomer cement. Colonization by the bacterium was assessed by weight gain and scanning electron microscopy. Initial colonization occurred after about 3 days, and the specimens were usually completely covered by the fourth day. There were statistically significant differences between materials for weight gain, a strong correlation between weight gain and surface free energy of the materials measured as droplet contact angle (r = 0.9) and a moderate correlation between weight gain and surface roughness (r = 0.6). |
8043559 | Evaluation of surgical options in menorrhagia. | Total abdominal and vaginal hysterectomy has been the standard treatment for intractable and unmanageable menorrhagia for many years. However, in the last few years, hysteroscopic treatment of menorrhagia through surgical resection and/or ablation of the endometrial cavity has gained success. Over 625,000 hysterectomies are performed each year in the USA alone. More than 30% are done for menorrhagia as a primary diagnosis. Three times more hysterectomies are performed using the abdominal route than the vaginal approach. Morbidity is higher using the abdominal route alone. Complications of abdominal and vaginal hysterectomies will be briefly discussed. Menorrhagia caused by submucous fibroids can be treated hysteroscopically. A review of methods, complications, advantages and long-term follow up will be presented. Laparoscopically-assisted vaginal hysterectomy (LAVH) is the latest surgical option offered for menorrhagia. The advent of a hysteroscopic approach to the treatment of menorrhagia and careful analysis of the advantages and disadvantages of LAVH will be discussed. |
8043558 | Menorrhagia--a pragmatic approach to the understanding of causes and the need for investigations. | Menorrhagia is a symptom denoting excessively heavy menstrual bleeding. It is a complaint that is difficult to verify objectively in many cases, even with a detailed case history. Issues of perception and tolerance of symptoms are important in whether a patient presents to a doctor, and this varies considerably from one society to another. Research studies indicate that the upper limit of normal blood loss is between 60 and 80 ml/month. Above this level women tend to become progressively iron deficient. Hence, any development which may help the precision of this assessment is valuable, and several of these will be discussed. Causes of menorrhagia can be divided into three groups: (1) pelvic diseases, such as myomata and adenomyosis; (2) systemic disorders, such as coagulopathies and hypothyroidism; and (3) dysfunctional uterine bleeding--a diagnosis of exclusion. Investigations are mainly aimed at improving the precision of the underlying diagnosis, defining the severity of the condition and excluding anaemia. Hence, the most important investigations are a full blood count, a diagnostic hysteroscopy and endometrial sampling. In clinical practice, other specific investigations need only be carried out if there are unusual features in the history or examination, or if previous treatments have failed. In a research situation there have been numerous studies aimed at elucidation of the mechanisms of heavy bleeding and some of these will be reviewed. |
8043557 | Endometrial ablation in the treatment of menorrhagia. | A prospective 5-year multicentre study, involving three UK gynaecology centres with a special interest in endoscopic laser surgery, was set up to determine the safety, acceptability, clinical effectiveness and complications of neodymium yttrium-aluminium-garnet laser ablation of the endometrium in the treatment of menorrhagia. A total of 2342 women with disabling menorrhagia that was unresponsive to medical therapy were involved. The main outcome measures were: preoperative endometrial preparation; duration of laser ablation, intra- and postoperative complications, amenorrhoea rate, oligomenorrhoea rate, and the women's subjective assessment of treatment. No major complications occurred in the 2342 treatments. Nine (0.4%) cases of transient fluid overload, 11 (0.5%) of infection and five (0.2%) of uterine perforation occurred. None of the women required a laparotomy. The mean duration of the laser ablation was 24 min. The post-surgery amenorrhoea rate was higher in women pretreated with danazol. Of the 1866 women followed up for at least 1 year after treatment, 1043 (56%) developed complete amenorrhoea, 701 (38%) reported continuing but satisfactorily reduced menstruation, and 122 (7%) patients failed to improve with the first treatment (57 of these 122 women responded to a second laser ablation). Overall, 1744 (93%) had a satisfactory response to laser ablation and only 33 (1.8%) required subsequent hysterectomy. In conclusion, this study showed that hysteroscopic endometrial laser ablation is an acceptable alternative to hysterectomy for the treatment of menorrhagia. |
8043556 | Assessment of medical treatments for menorrhagia. | Although usually not life-threatening, dysfunctional uterine bleeding (DUB) can cause discomfort and disruption to life for many women. It has been poorly researched in the past, primarily because of difficulties in trying to accurately measure blood loss and response to treatment. There are several different therapies currently available but, for many, actual evidence of their efficacy is lacking from scientific data. Progestogens are the most frequently prescribed drugs for the treatment of DUB. Data support their use in anovulatory women but a number of comparative trials have shown that an overall reduction in blood loss of only 20% is achieved in ovulatory women. Their use, therefore, must be questioned as the first line of treatment. Combined oral contraceptives were at one time popular but whether the low-dose, current generation pills are equally effective awaits appropriate trials. Prostaglandin synthetase inhibitors can be useful, with up to a third of women with menorrhagia benefiting from a reduction of between 25% and 35% in blood loss. A proportionally greater reduction is seen in women with more excessive bleeding. Antifibrinolytic drugs have been shown to reduce menstrual blood loss in DUB by 50% and would be useful in women in whom oestrogens are contraindicated. Gonadotrophin-releasing hormone analogues are highly effective because of their ability to induce amenorrhoea, but long-term use is contraindicated because of their hypo-oestrogenic effects. One other effective therapy for menorrhagia has been danazol.(ABSTRACT TRUNCATED AT 250 WORDS) |
8043542 | Five year survival rate in endometrial carcinoma stages I--II: influence of degree of tumour differentiation, age, myometrial invasion and DNA content. | To compare the prognostic capability of clinical stage, tumour differentiation, myometrial invasion, age and DNA content in endometrial carcinoma. Then to use the results to identify a small, high risk group suitable for more intensive adjuvant therapy. A prospective five year follow up between June 1980 and June 1987. Department of Oncology, gynaecological section, University Hospital, Lund, Sweden. Endometrial tissue was obtained immediately prior to treatment for flow cytometric DNA analysis. Two hundred and fifty-one patients referred for treatment. None. Age, myometrial invasion of greater than 50%, and number of DNA populations (ploidy) were the only significant parameters related to survival. By combining myometrial invasion and number of DNA populations, we divided the patients into four groups. A very small high risk group was identified (7%) with a low survival rate (61%). Two intermediate groups with either myometrial invasion exceeding 50% or with more than one DNA population present constituted 34% of the patients and these had an overall survival rate of 75% and a relatively large low risk group of 59% of the patients (with a survival rate of 95%) was constructed out of those without deep myometrial invasion and demonstrating only one DNA population. These data suggest that number of DNA populations and depth of myometrial invasion could be combined to identify a small high risk group (7%) with a low survival rate (61%) suitable for adjuvant therapy. |
8043541 | The treatment of stage I carcinoma of the cervix in the west of Scotland 1980-1987. | To examine the results of different treatments for Stage IA and IB carcinoma of the cervix in patients treated in the West of Scotland between 1980 and 1987. A retrospective review of case records. The Beatson Oncology Centre, Western Infirmary and Belvidere Hospital, Glasgow, and the departments of gynaecology of hospitals in the west of Scotland. One hundred and five patients with Stage IA and 420 patients with Stage IB carcinoma of the cervix. A variety of treatments were used for women with Stage IA disease, with an overall actuarial five year survival of 100%. The overall actuarial five year survival for women with Stage IB disease was 79.5%. Patients with Stage IB disease treated by radical hysterectomy (n = 123) or radical radiotherapy (n = 229) had similar five year survival rates (86.3% and 79.5%, respectively), whereas patients treated initially by nonradical surgery (n = 68) had a significantly worse five year survival (68.1%; P = 0.008). These results emphasize the need for adequate and appropriate surgery and the centralisation of treatment for early cervical cancer. |
8043540 | A randomised controlled trial of prophylaxis of post-abortal infection: ceftriaxone versus placebo. | To investigate the incidence of post-operative infection after first trimester abortion in women treated with a long-acting cephalosporin (ceftriaxone) compared with low risk patients receiving no treatment and with high risk patients receiving our standard treatment of ampicillin/pivampicillin and metronidazole. A prospective, randomised controlled trial. Department of Obstetrics and Gynaecology, Rigshospitalet, University of Copenhagen, Denmark. Nine hundred and ninety-six women, admitted on an outpatient basis for legal termination of pregnancy at 12 weeks or less of gestation, were included in the study after giving informed consent. The women were divided into high risk and low risk categories and allocated either to treatment with ceftriaxone or to standard treatment. For high risk patients the standard treatment was initiated by a peroperative injection of ampicillin and metronidazole, followed by oral doses of metronidazole and pivampicillin three times daily for four days. No prophylactic antibiotics were given to the women randomised to standard treatment in the low risk group. All women were kept under observation, and, between six and 14 days postoperatively, underwent pelvic examination. Clinical endpoints were noted. Post-operative pelvic inflammatory disease in women applying for legal first trimester abortion. Seven hundred and eighty-six women fulfilled the criteria for evaluation. A tendency toward a prophylactic effect of ceftriaxone was observed in most clinical findings. A significant prophylactic effect of ceftriaxone was found in the low risk group. This study demonstrated a significant reduction in post-operative pelvic inflammatory disease in low risk patients, who were applying for legal first trimester abortion, treated peroperatively with ceftriaxone. No significant difference was demonstrated between high risk patients treated with ceftriaxone or ampicillin/pivampicillin and metronidazole. |
8043539 | Endometrial resection follow up: late onset of pain and the effect of depot medroxyprogesterone acetate. | To observe longer term (9 to 18 months) follow up of women after a transcervical resection of the endometrium (TCRE) and the effect of post-operative medroxyprogesterone acetate on the results. An observational study. A district public hospital and a nearby private hospital in Sydney, Australia. Sixty-one women who underwent TCRE from January to December 1991 were contacted 9 to 18 months after the procedure. They were questioned about symptoms and levels of satisfaction at six months, 12 months and at the time of interview, 9-18 months after the procedure. The 27 women treated from 1 January to 31 August 1991 were given medroxyprogesterone acetate 150 mg at the time of surgery. From 1 September to 31 December 1991 no medroxyprogesterone acetate was given (32 women). Two women underwent immediate hysterectomy, and are included as unsuccessful TCREs but are excluded from description of effects of medroxyprogesterone acetate on the results of TCRE. Late onset, defined as after 12 months, of pain with or without bleeding occurred in 7 out of 52 women (13.5%). Overall, 49 out of 61 women (80.3%) were satisfied with the operation at the time of interview, 9 to 18 months post-operatively. Success rates, measured by satisfaction, were 89% (24/27) in the medroxyprogesterone acetate group and 75% (24/32) in the no medroxyprogesterone acetate group. Follow up after endometrial resection revealed that a definite subgroup of women develop late onset of pain with or without bleeding. Results at four to six months do not necessarily correlate with longer term outcomes. This needs to be investigated with larger, long term follow up studies, as does the apparently beneficial effects of medroxyprogesterone acetate on the long term results of TCRE. |
8043538 | Oligohydramnios sequence: the spectrum of renal malformations. | To assess the value of the autopsy findings on a series of infants dying with features of the oligohydramnios sequence, with particular reference to anomalies of the renal tract. Retrospective review. Pathology departments serving three maternity units in Manchester. Eighty-nine infants having an autopsy examination between 1976 and 1990. Thirty-two (34%) infants had bilateral renal agenesis, 30 (34%) had bilateral cystic dysplasia, eight (9%) had unilateral agenesis with unilateral cystic dysplasia, four (4%) had renal histology characteristic of a recessively inherited disorder (two cases of renal tubular dysgenesis and two cases of autosomal recessive (infantile) polycystic disease), nine (10%) had minor urinary tract anomalies, and three (3%) had morphologically normal renal tracts. Forty-eight (54%) infants had congenital abnormalities other than those resulting from oligohydramnios sequence; most commonly, these were anomalies of the sporadic VATER association, but in four infants the extra renal anomalies present allowed recognition of a recessively inherited syndrome (Meckel's in three cases, Smith-Lemli-Opitz in one). A detailed autopsy is vital in assessment of infants with oligohydramnios sequence resulting from a congenital abnormality of the kidneys or urinary tract. This applies equally to second trimester fetuses following miscarriage or therapeutic abortion, to stillborn infants, or to neonatal deaths. |