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Biomedical subjects

S David

Publications and source records attributed to S David.

At least 37 records · Page 2Linked to original sources
PubMed1999

No evidence for astrogliosis in brains of schizophrenic patients. A post-mortem study.

Schizophrenia is clinically and neuropsychologically characterized by severe cognitive and functional impairment suggesting the presence of a neurodegenerative process in the brains of affected individuals. A variety of neuroanatomical changes have been described such as loss and disorientation of neurons in grey and white matter and cortical atrophy. However, the neuropathological basis for schizophrenia is still unclear. In the present study we monitored the density of GFAP-positive astrocytes in brains of 33 schizophrenic patients and 26 healthy controls. Both grey matter (entorhinal cortex and subiculum) and white matter (premotor cortex, subventricular zone of the third ventricle and next to inferior horn) structures were measured bilaterally. The overall finding was that there is no evidence for increased astrogliosis in brains of schizophrenic patients vs healthy controls. Therefore, degeneration is unlikely to be the main neuropathological mechanism in schizophrenic brains.

Astrocytes↗
PubMed1999

Occlusal outcome in patients undergoing orthognathic surgery with internal fixation.

Fifty consecutive patients undergoing orthognathic surgery with internal fixation (IF) were studied retrospectively with a weighted Peer Assessment Rating (PAR) Index to assess occlusal outcome at the end of all active treatment, and compared with 50 patients who had undergone treatment for malocclusion by orthodontic means alone. In the surgically treated patients, the mean percentage reduction in the weighted PAR Index was 83% and 31 out of 38 patients (82%) were 'greatly improved'. This implies a high standard of treatment in terms of the occlusal outcome. There was no difference in the proportion of patients having a final weighted PAR Index of less than 10 and no significant difference in the final weighted PAR Index between the two groups. This suggests that the occlusal outcome is no different whether patients undergo orthognathic surgery or orthodontic treatment alone, and that excellent occlusal results can be achieved in patients undergoing orthognathic surgery with internal fixation.

Humans↗
PubMed1999

An overview of haemodialysis and oxidant stress.

Today's patient population is increasingly older. Patients with chronic renal failure therefore start extracorporeal substitutive treatment having congestive heart failure, chronic liver disease, diabetes and so forth. In these patients, however, long-term haemodialytic treatment may add further aggravation on their pre-existing pathological conditions. Oxidative stress and alterations in lipid metabolism are caused by haemodialysis mainly due to (1) bioincompatibility type of reactions such as production of reactive oxygen species by inflammatory cells due to complement-mediated or -independent pathways, and (2) the imbalance between oxidants and antioxidants due to the diffusive loss of hydrophilic vitamins such as ascorbic acid. The events related to the oxidant stress may sustain a state of chronic inflammation. Recent advances suggest that atherosclerosis and proliferation of the smooth muscle are initiated and sustained by inflammatory mechanisms. Therefore, attempts to counterbalance the prooxidant effect of haemodialysis and to reduce the chronic inflammatory state will be presented.

Cardiovascular Diseases↗
PubMed1999

A new approach to restorative dentistry: fabricating ceramic restorations using CEREC CAD/CAM.

Ceramic materials provide an alternative when choosing a tooth-colored restoration. Currently, posterior composite restorations can be used to achieve esthetic restorations; however, they have many disadvantages with regard to wear, polymerization shrinkage, discoloration, marginal leakage, and technique sensitivity. The use of CEREC CAD/CAM enables the dentist to place feldspathic porcelain (Vitablocs Mark II) and machinable glass ceramic (Dicor MGC) restorations in a single visit. When compared to composite materials, these materials closely approximate the physical properties of enamel in compressive and tensile strength and wear resistance. This study evaluated 50 CEREC CAD/CAM restorations after 4 years in service. Restorations ranged from Class I to 7/8s crown preparations.

Adult↗
PubMed1998

Unique responses of differentiating neuronal growth cones to inhibitory cues presented by oligodendrocytes.

During central nervous system development, neurons differentiate distinct axonal and dendritic processes whose outgrowth is influenced by environmental cues. Given the known intrinsic differences between axons and dendrites and that little is known about the response of dendrites to inhibitory cues, we tested the hypothesis that outgrowth of differentiating axons and dendrites of hippocampal neurons is differentially influenced by inhibitory environmental cues. A sensitive growth cone behavior assay was used to assess responses of differentiating axonal and dendritic growth cones to oligodendrocytes and oligodendrocyte- derived, myelin-associated glycoprotein (MAG). We report that >90% of axonal growth cones collapsed after contact with oligodendrocytes. None of the encounters between differentiating, MAP-2 positive dendritic growth cones and oligodendrocytes resulted in growth cone collapse. The insensitivity of differentiating dendritic growth cones appears to be acquired since they develop from minor processes whose growth cones are inhibited (nearly 70% collapse) by contact with oligodendrocytes. Recombinant MAG(rMAG)-coated beads caused collapse of 72% of axonal growth cones but only 29% of differentiating dendritic growth cones. Unlike their response to contact with oligodendrocytes, few growth cones of minor processes were inhibited by rMAG-coated beads (20% collapsed). These results reveal the capability of differentiating growth cones of the same neuron to partition the complex molecular terrain they navigate by generating unique responses to particular inhibitory environmental cues.

Animals↗
PubMed1998

Abnormal properties of creatine kinase in Alzheimer's disease brain: correlation of reduced enzyme activity and active site photolabeling with aberrant cytosol-membrane partitioning.

The report shows that Alzheimer's disease (AD) brain creatine kinase (CK) is modified such that the nucleotide binding site of CK is blocked and that abnormal partitioning of CK between the soluble and pellet fractions occurs. First, CK activity was 86% decreased in AD brain homogenates in comparison to age-matched controls. Secondly, over a 23.5 fold greater 32P photoincorporation of [alpha 32P]8N3ATP was observed into CK of control vs. AD samples. Also, a 7.4-fold increase of enzyme induced 32P incorporation was observed in controls vs. AD samples by incubation with [gamma 32P]ATP. Thirdly, Western blot analysis showed that CK copy numbers in the AD homogenate were decreased by less than 14% in comparison to controls. However, analysis showed that control supernatant and pellet fractions contained 10.3 and 0.4 times the CK copy number found in the corresponding AD fractions. 32P incorporation by both photolabeling and enzyme catalyzed incorporation of radiolabel followed CK activity and not CK copy number. Further, [alpha 32P]ADP and [gamma 32P]ATP incorporated 32P into control brain and purified brain CK equally well, indicating that a mechanism different from gamma-phosphoryl transfer is involved in the enzymatic incorporation of radiolabel. Also, the level of abnormal partitioning of CK into AD brain pellet correlated with the decreased [32P]8N3GTP photolabeling and abnormal partitioning of beta-tubulin, a protein known to be aberrantly modified in the AD brain. This indicates that a common chemistry is affecting both CK and tubulin in AD.

Alzheimer Disease↗
PubMed1998

Properties of human anti-group B streptococcal type III capsular IgG antibody.

The group B streptococcus is the commonest cause of bacterial infection in the newborn. In an attempt to prevent these infections, various vaccines are in development, most of which contain at least one of the capsular carbohydrates of the bacterium. We present new detailed data on the natural human antibody response to the type III capsular carbohydrate as we believe it is important to ascertain equivalent data for any new candidate vaccine in order to predict efficacy. We demonstrate that naturally occurring IgG is opsonically active in a complement-dependent manner, that fractions of differing avidity isolated from single donors have broadly similar opsonic activity, that the clonotypes from four individuals are restricted in number to a maximum of 15, and that binding kinetics ascertained using a resonant mirror biosensor show that specific antibodies have a moderately high affinity (mean Kd = 1.1e-8 M).

Adult↗
PubMed1998

A prospective randomized trial of triage angiography in acute coronary syndromes ineligible for thrombolytic therapy. Results of the medicine versus angiography in thrombolytic exclusion (MATE) trial.

OBJECTIVES: The purpose of this study was to determine if early triage angiography with revascularization, if indicated, favorably affects clinical outcomes in patients with suspected acute myocardial infarction who are ineligible for thrombolysis. BACKGROUND: The majority of patients with acute myocardial infarction and other acute coronary syndromes are considered ineligible for thrombolysis and therefore are not afforded the opportunity for early reperfusion. METHODS: This multicenter, prospective, randomized trial evaluated in a controlled fashion the outcomes following triage angiography in acute coronary syndromes ineligible for thrombolytic therapy. Eligible patients (n=201) with <24 h of symptoms were randomized to early triage angiography and subsequent therapies based on the angiogram versus conventional medical therapy consisting of aspirin, intravenous heparin, nitroglycerin, beta-blockers, and analgesics. RESULTS: In the triage angiography group, 109 patients underwent early angiography and 64 (58%) received revascularization, whereas in the conservative group, 54 (60%) subsequently underwent nonprotocol angiography in response to recurrent ischemia and 33 (37%) received revascularization (p=0.004). The mean time to revascularization was 27+/-32 versus 88+/-98 h (p=0.0001) and the primary endpoint of recurrent ischemic events or death occurred in 14 (13%) versus 31 (34%) of the triage angiography and conservative groups, respectively (45% risk reduction, 95% CI 27-59%, p=0.0002). There were no differences between the groups with respect to initial hospital costs or length of stay. Long-term follow-up at a median of 21 months revealed no significant differences in the endpoints of late revascularization, recurrent myocardial infarction, or all-cause mortality. CONCLUSIONS: Early triage angiography in patients with acute coronary syndromes who are not eligible for thrombolytics reduced the composite of recurrent ischemic events or death and shortened the time to definitive revascularization during the index hospitalization. Despite more frequent early revascularization after triage angiography, we found no long-term benefit in cardiac outcomes compared with conservative medical therapy with revascularization prompted by recurrent ischemia.

Adult↗
PubMed1998

Psychosocial work environment and cardiovascular risk factors in an occupational cohort in France.

STUDY OBJECTIVE: Concordant results have been reported in several studies for the effects of job stress on cardiovascular disease, but the potential mechanisms of these effects have seldom been explored. The aim of this study was therefore to examine, in women and men, the cross sectional relations between psychosocial work variables (psychological demands, decision latitude, and social support) and cardiovascular risk factors (hypertension, hyperlipidaemia, diabetes, overweight, smoking, and alcohol consumption). PARTICIPANTS: The original cohort comprised 20,625 volunteers (men aged from 40 to 50 and women from 35 to 50) employed by the French Company Electricité De France-Gaz De France and followed up yearly since 1989. The study was restricted to the 13,226 volunteers in the cohort who were still working and answered a self administered questionnaire on psychosocial work factors in 1995. DESIGN: Data were based on replies to this questionnaire. Three psychosocial work environment exposure scores were used to assess psychological demands, decision latitude, and social support at work respectively. The main outcome measures were the prevalence of hypertension, hyperlipidaemia, and diabetes within the previous 12 months, overweight, smoking, and alcohol consumption. MAIN RESULTS: Psychosocial work factors were significantly associated with hypertension, hyperlipidaemia, overweight, smoking, and alcohol consumption, but not with diabetes. In men, low decision latitude was associated with hypertension, high decision latitude and high social support with overweight, low decision latitude with alcohol consumption. Moreover, the risk of hyperlipidaemia increased in men exposed to both high psychological demands and low social support. In women, low decision latitude was related to hyperlipidaemia, high psychological demands with overweight, high psychological demands and high decision latitude with smoking, and low social support with alcohol consumption. CONCLUSIONS: These cross sectional results underline the potential effects of psychosocial work characteristics on cardiovascular risk factors and the differences between the effects of job stress in men and women, and confirm the direct mechanisms (through physiological variables) and indirect mechanisms (through behavioural risk factors) potentially involved in the relation between psychosocial work characteristics and cardiovascular disease.

Adult↗
PubMed1998

Dystonin is an essential component of the Schwann cell cytoskeleton at the time of myelination.

A central role for the Schwann cell cytoskeleton in the process of peripheral nerve myelination has long been suggested. However, there is no genetic or biological evidence as yet to support this assumption. Here we show that dystonia musculorum (dt) mice, which carry mutations in dystonin, a cytoskeletal crosslinker protein, have hypo/amyelinated peripheral nerves. In neonatal dt mice, Schwann cells were arrested at the promyelinating stage and had multiple myelinating lips. Nerve graft experiments and primary cultures of Schwann cells demonstrated that the myelination abnormality in dt mice was autonomous to Schwann cells. In culture, dt Schwann cells showed abnormal polarization and matrix attachment, and had a disorganized cytoskeleton. Finally, we show that the dt mutation was semi-dominant, heterozygous animals presenting hypo- and hyper-myelinated peripheral nerves. Altogether, our results suggest that dt Schwann cells are deficient for basement membrane interaction and demonstrate that dystonin is an essential component of the Schwann cell cytoskeleton at the time of myelination.

Animals↗
PubMed1998

Psychosocial factors at work and subsequent depressive symptoms in the Gazel cohort.

OBJECTIVE: This study attempted to establish whether psychosocial factors at work are predictors of depressive symptoms in a prospective cohort of men and women employed in a wide variety of occupations by the French national company Electricité De France - Gaz De France (EDF-GDF). METHODS: This prospective cohort study followed the Gazel cohort by means of annual self-administered questionnaires and independent data obtained from the medical and personnel departments of the company. The self-administered questionnaire, in 1995, provided information about the psychosocial work environment characteristics, psychological job demands, decision latitude, and social support at work. Depressive symptoms were assessed by the Center for Epidemiologic Studies Depression (CES-D) Scale in the 1996 questionnaire. Potential confounding variables were age, marital status, and number of children, assessed in the 1995 questionnaire, stressful personal and occupational events during the previous 12 months, assessed in the 1996 questionnaire, and educational level, occupation and previous absenteeism for mental disorders, assessed from the independent data provided by EDF-GDF. The subjects were 11 552 workers (8422 men aged 46-56 years in 1995 and 3130 women aged 41-56 years) who answered the 1995 and 1996 questionnaires and were working during this period. RESULTS: High levels of psychological demands, low levels of decision latitude, and low levels of social support at work were significant predictors of subsequent depressive symptoms in both the men and the women. These results were unchanged after adjustment for potential confounding variables. CONCLUSIONS: The results strongly support the possibility that psychosocial factors at work are predictive of depressive symptoms.

Adaptation, Psychological↗
PubMed1998

[Value of ultrasound in diagnosis of appendicitis in childhood].

Ultrasonography has been shown to be valuable in diagnosis of appendicitis in children. For the management of cases where clinical and ultrasonography findings lead to different results, we evaluated standard therapeutical concepts which have been proved to be reliable in our clinic.

Acute Disease↗
PubMed1997

[Evaluation of the hospital management of insulin-dependent diabetics].

OBJECTIVE: There is a known relationship between blood glucose control and development or progression of complications in diabetes mellitus. The aim of our study was to assess the quality of hospital care in patients with insulin-dependent diabetes. PATIENTS AND METHODS: A prospective study was conducted over a 6-month period (April 95-September 95) to perform a clinical audit comparing results obtained with care standards. The study group included 257 consecutive patients (age range 15-39 years) who consulted the hospital outpatient clinic of were hospitalized for insulin-dependent diabetes mellitus RESULTS: Results differed depending on the care standards used for comparison. There were 45 patients (17%) who consulted 4 times or more; 43% of the patients were not hospitalized and 32% did not had a fundus examination during the preceding year. There was a 51% deviation from the standard number of capillary blood glucose measurements and 72% of the patients stated they adapted their insulin dose. Mean glycosylated hemoglobin level (HPLC method) was 9.78 +/- 2.37% (standard = 7%). CONCLUSION: This assessment of hospital care demonstrated a deviation of medical surveillance from standard care. More frequent consultations would help improve patient information. It is important to recall that an annual hospitalization and rigorous application of clinical surveillance with annual fundus examination are essential. Information provided by physicians, nurses and dietitians should be an integral part of hospital care. Likewise, it is undoubtedly useful to provide psychological counselling for diabetic patients. A reassessment should evaluate the impact of such recommendations in order to determine the impact, in terms of reduced mortality, of improved hospital care.

Adolescent↗