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Biomedical subjects

M Petit

Publications and source records attributed to M Petit.

At least 19 recordsLinked to original sources
PubMed2002

Cognitive patterns in subtypes of schizophrenia.

AIM: Because of the heterogeneity of schizophrenia, this study researched different cognitive patterns in distinct subtypes of schizophrenic patients. METHODS: Thirty-five Diagnostic and Statistical Manual IV (DSM IV) schizophrenic patients and 35 healthy controls were included. Patients were categorized into deficit, disorganized and positive subtypes with the schedule for the deficit syndrome (SDS) and the positive and negative syndrome scale (PANSS). Executive/attentional functions were assessed with the modified card sorting test (MCST), a test of verbal fluency, the trail making test (TMT) and the Stroop color-word test (Stroop test). Episodic memory was explored through the California verbal learning test (CVLT). RESULTS: The positive subtype had some executive/attentional (fluency and Stroop tests) and mnesic performances in the normal range, suggesting the preservation of good cognitive skills. In contrast, the deficit and disorganized subtypes had major mnesic and executive/attentional dysfunctions compared to healthy subjects. The deficit subtype compared to the control group performed predominantly worse on the MCST and fluency, whereas the disorganized subtype had the lowest scores on the TMT and the Stroop test. CONCLUSION: This study showed distinct cognitive patterns in deficit, disorganized and positive patients in comparison with the controls, suggesting a heterogeneous cognitive dysfunction in schizophrenia.

Adolescent↗
PubMed2002

The -2 bp deletion in exon 6 of the 'alpha 7-like' nicotinic receptor subunit gene is a risk factor for the P50 sensory gating deficit.

Abnormality in the P50 auditory-evoked potential gating is an endophenotype associated with schizophrenia. Biochemical and genetic studies have suggested that the alpha 7 nicotinic acetylcholine receptor (nAChR) is involved in this sensory gating deficit. Two related alpha 7 genes (CHRNA7 and CHRNA7-like gene) resulting from a partial duplication (from exon 5 to exon 10) are present in the human genome. Two types of genetic variation, a large deletion and a -2 base-pair deletion in exon 6 resulting in a truncation of the open reading frame, affect specifically the CHRNA7-like gene. We developed a simple multiplex PCR assay on genomic DNA, allowing the quantification of the number of exons 6 and the distinction of all possible exon 6 genotypes. Genotyping of 70 schizophrenic patients and 77 controls showed that carrying at least one -2 bp deletion of exon 6 did not constitute a risk factor for schizophrenia. In contrast, the distribution of genotypes differed significantly between subjects with normal and abnormal P50 ratios, with an over-representation of genotypes carrying at least one -2 bp deletion of exon 6 among subjects exhibiting an abnormal P50 ratio. We thus conclude that the -2 bp deletion within the CHRNA7-like gene is a risk factor for P50 sensory gating deficit. Interestingly, most of the effect came from the non schizophrenic group, which may suggest that in schizophrenic patients other risk factors account for the large proportion of subjects exhibiting an abnormal P50 ratio.

Adult↗
PubMed2001

No evidence for linkage between COMT and schizophrenia in a French population.

Catechol-O-methyltransferase is a candidate in the predisposition to schizophrenia both because of its function and the position of its gene. A multipoint non-parametric linkage analysis and a transmission disequilibrium test were performed on 42 multiplex families genotyped for Pml I and Bcl I polymorphisms using two definitions of the affected phenotype. Neither linkage nor preferential transmission of any allele or haplotype was detected, failing to replicate previous positive findings.

Alleles↗
PubMed2001

Concordance of deficit and non-deficit subtypes in siblings affected with schizophrenia.

Deficit and non-deficit subtypes were examined for their concordance in 83 sibling pairs of 109 schizophrenic patients belonging to 46 multiply affected families. Using a sib-pair method, we have found that the distribution of deficit and non-deficit syndromes in sibling pairs of schizophrenic patients differed significantly from chance expectation. This familial aggregation suggests that the syndrome may be used to define phenotypes for genetic studies.

Adult↗
PubMed2001

Saccadic and smooth-pursuit eye movements in deficit and non-deficit schizophrenia.

We have analyzed eye movement performances in schizophrenics showing primary negative or deficit symptoms (n=16) and non-deficit schizophrenics (n=55), and compared them with those of controls (n=34) in order to study the relationships between negative symptoms and eye movement abnormalities. Patients were subtyped into deficit and non-deficit subgroups using the Schedule for the Deficit Syndrome. Three oculomotor paradigms were used: smooth pursuit, a reflexive saccade paradigm and an antisaccadic task. The smooth pursuit gain was significantly decreased (and the rate of catch-up saccades increased) in schizophrenics as compared with controls, but no difference was observed between patient groups. In the reflexive saccade paradigm, no difference was found between controls and patients, except for latency in deficit patients. In the antisaccade paradigm, the number of errors and the latency of successful antisaccades were significantly increased in schizophrenics as compared with controls. The latency of successful antisaccades in both directions was significantly increased in deficit patients as compared with non-deficit patients. The latency of rightward successful antisaccades was significantly increased as compared with the latency of leftward antisaccades in deficit patients only. However, when patients were classified into negative and non-negative groups using the PANSS, no difference was found in the antisaccade paradigm. Smooth pursuit impairment does not seem to depend on the primary enduring negative symptoms.In deficit schizophrenics, the abnormalities observed in the antisaccadic task are consistent with prefrontal dysfunction, and may suggest parietal lobe dysfunction as well.

Adult↗
PubMed2001

Perfusion of myocardial segments of the right ventricle: role of the left coronary artery in infarction of the right ventricle.

In a series of 88 human hearts, from individuals aged between 24 h and 94 yr (x= 61.09 +/- 21.96), the coronary arterial distribution of the right ventricle was studied using a modified Selvester's system of segmentation. Postmortem angiographies and microdissection techniques were used. The analysis of the six segments of the right ventricle shows that the three anterior segments, basal, mesial, and--less frequently--apical, present a type of irrigation that is practically constant and is dual. The postero-basal and postero-mesial segments are irrigated almost exclusively by the right coronary artery. In the remaining segments the vascularization was of mixed type, although a considerable degree of exclusive arterial perfusion was observed in the antero-apical segment. The segmental analysis allows us to conclude that although arterial vascularization of the right ventricle depends fundamentally on the right coronary artery, the anterior interventricular artery irrigates more than 20% of the right ventricular myocardium. Results from segmental analysis are compared with data from clinical and necropsic studies.

Adult↗
PubMed2001

Evidence of a cohort effect for age at onset of schizophrenia.

OBJECTIVE: The authors address whether a possible age-at-onset cohort effect may have introduced a bias into anticipation studies of schizophrenia. METHOD: A retrospective review of the medical records of all admissions for psychotic disorders (N=877) was conducted. All subjects with a confirmed DSM-IV diagnosis of schizophrenia and age-at-onset data were included (N=419). For analyses, subjects were placed into one of three successive birth cohorts: 1905-1944 (N=96), 1945-1964 (N=200), and 1965-1984 (N=123). RESULTS: The mean age at first appearance of psychotic symptoms and, similarly, the mean age at first hospitalization significantly decreased over time in successive birth cohorts (25.3, 23.3, and 20.4 years, respectively, for age at first appearance of psychotic symptoms). CONCLUSIONS: This potential birth cohort effect for age at onset of schizophrenia needs to be incorporated into genetic models.

Adult↗
PubMed2001

Use of rapid enzymatic assays to study the distribution of faecal coliforms in the Seine river (France).

In 1997 and 1998 faecal contamination of the Seine river and its estuary was studied for the first time by rapid enzymatic methods, based on the presence of the beta-D-glucuronidase enzyme in E. coli, in parallel with traditional plate counts of faecal coliforms on specific culture medium. Our study focused on a 450 km stretch of the river, including the Parisian area, and presenting highly variable levels of faecal pollution. Both methods showed that wastewater outfalls of the Parisian area and the presence of a maximum turbidity zone (at the mouth of the estuary) had a strong impact on the abundance of faecal coliforms in the river. Downstream from the Parisian outfalls, beta-D-glucuronidase activity measurements decreased 5-6x less rapidly than plate counts suggesting that rapid enzymatic assays could detect enzymatically-active but non-culturable bacteria.

Biological Assay↗
PubMed2000

Lack of association of serum lipoprotein (a) levels with type-2 diabetes mellitus in patients with angiographically defined coronary artery disease.

Multiple studies have demonstrated that elevated serum lipoprotein (a) [Lp(a)] levels are independent predictors for coronary artery disease (CAD) in subjects without diabetes mellitus (DM). However, their contribution in patients with DM is controversial and still requires clarification. We determined serum Lp(a) levels in 355 consecutive Caucasian patients (271 men and 84 women) with angiographically documented CAD, and in 100 control subjects (58 men and 42 women) who were clinically free of cardiovascular disease. In addition, the association of serum Lp(a) levels with type-2 DM in patients with CAD was investigated after reassigning patients according to the diagnosis of type-2 DM (61 men and 40 women with type-2 DM and 210 men and 44 women without). No gender differences in Lp(a) levels were observed between men and women (patients and control subjects). Patients with CAD had higher Lp(a) levels than the control subjects (33 (14-74) vs. 13 (9-29) mg/dl, P<0.001). Elevated Lp(a) levels (defined as >90th percentile of controls) were significantly more prevalent in men and women with CAD (35% and 28%, respectively) than in control subjects (13% and 10%, respectively). Serum Lp(a) levels correlated with LDL cholesterol (r=0.22, P<0.001) and apo B levels (r=0.18, P<0.03) in patients and control subjects. Stepwise discriminant analysis revealed that Lp(a) was an independent risk factor for the presence of CAD, independent of smoking, hypertension, type-2 DM, LDL and HDL cholesterol or apo A1 and B levels. When patients were studied according to the spread of CAD (evaluated as the number of narrowed vessels), no differences in serum Lp(a) levels were observed, nor was there a higher prevalence of elevated Lp(a) levels. Finally, when patients were re-assigned according to the diagnosis of type-2 DM, no effect of apo B and LDL-C levels on Lp(a) was found (r=0.06, P=n.s. and 40.14, P=n.s., respectively) and serum Lp(a) levels neither associated nor contributed to the extent of CAD. Our results showed that serum Lp(a) levels are increased in patients with angiographically documented CAD, but there were no significant differences between diabetic and non-diabetic patients, which indicates that elevated Lp(a) levels are specifically associated with CAD but not with type-2 DM.

Adult↗
PubMed2000

Arterial vascularization of the human moderator band: an analysis of this structure's role as a collateral circulation route.

In the human heart, the moderator band, or trabecula septomarginalis, is a muscle column that courses inferiorly from the right portion of the interventricular septum to the base of the anterior papillary muscle of the right ventricle This muscular structure is crossed by one or more arteries, which come from the anterior interventricular artery and perfuses the anterior papillary muscle of the right ventricle. In order to clarify the arterial supply of this muscle column, we studied 28 adult hearts, free of any signs of coronary disorder. The path of the moderator band artery was followed by means of microdissection, and we studied the source, course, and interconnections made with other arteries. We observed that the source of the moderator band artery lies in the first three anterior septal arteries, most often in the second one. In relation to the short axis of the heart, the artery of the moderator band can either follow a horizontal path to the septal papillary muscle of the right ventricle or an oblique route to the moderator band, depending on the position of its source. In all the hearts studied, the moderator band artery made anastomotic connections at the base of the anterior papillary muscle of the right ventricle with various branches of the right coronary artery, which means that it can play a key role in collateral circulation following obstruction of the epicardium coronary arteries.

Adult↗
PubMed2000

Relationships among Bacterial Cell Size, Productivity, and Genetic Diversity in Aquatic Environments using Cell Sorting and Flow Cytometry.

The study of relationships between cell size and productivity is of key importance in microbial ecology to understand which members of natural aquatic communities are responsible for the overall activity and/or productivity. Flow sorting of microorganisms from different environmental samples was used to analyze the activity of bacterial cells depending on their biovolume. Bacterial cells from five different natural samples taken along the Mediterranean coast including fresh- and seawaters were incubated with tritiated leucine, then stained with SYTO 13 and sorted by flow cytometry according to their average side-angle-scattered (SSC) light. In all samples, a bell-shaped relationship was found between cell biovolume and activity, whereas activity of a given cell-size class varied between samples. In contrast, an inverse relationship was found between biovolumes and abundances. These results suggest that medium-sized cells with highest growth rates are probably submitted to intense grazing. For one sample, bacteria within five different size classes were sorted and the genetic diversity of cells within each sorted size class and that of the whole community were analyzed by the denaturing gradient gel electrophoresis (DGGE) method. The genetic diversity, as determined at the community level was highly represented into the pool of small cells, whereas only few species were present into larger cell subpopulations. The results suggest that only a few genotypes may be dominant within the largest and most productive cells. Furthermore, cell size polymorphism as well as heterogeneous cellular activities were found within some species.

Journal Article↗
PubMed2000

Early down-regulation of cytochrome P450 3A and 2E1 in the regenerating rat liver is not related to the loss of liver mass or the process of cellular proliferation.

AIMS/BACKGROUND: Conflicting data have been reported concerning the modification of cytochrome P450 expression in the regenerating liver. Ligation of branches of the portal vein (PBL) perfusing 70% of the liver parenchyma, which produces regeneration and atrophy within the same liver, constitutes an ideal model to study the relative specificity of the early events in the regenerating liver and their relationship to the loss of liver mass. METHODS: In this PBL model and in sham models, we studied the expression and the metabolic activities of two major cytochromes, CYP3A and CYP2E1, and the expression of inducible nitric oxide synthase protein (iNOS). They were simultaneously measured in the atrophying and regenerating liver lobes following PBL using Western Blot and HPLC methods. RESULTS: The metabolic activities of both cytochromes were transiently and simultaneously down-regulated in the regenerating and atrophying lobes during the first 2-5 h after PBL. No significant modification was observed at the protein level. In contrast, iNOS protein was significantly induced in both lobes. Similar results were observed after sham operation. CONCLUSIONS: The reduction of these CYP activities in both lobes after PBL and in sham livers suggests that other mechanisms than the regenerating process itself or the reduction of the liver mass might account for such down-regulation during the early phase of liver regeneration. The activation of nitric oxide (NO) and/or pro-inflammatory cytokine production provides clues to pathways liable to affect the CYP activities in the regenerating liver.

Animals↗
PubMed2000

Use of enzymatic methods for rapid enumeration of coliforms in freshwaters.

Rapid enumeration methods based on the enzymatic hydrolysis of 4-methylumbelliferyl-beta-D-galactoside and 4-methylumbelliferyl-beta-D-glucuronide were optimized for freshwaters. The enzymes beta-D-galactosidase (GALase) and beta-D-glucuronidase (GLUase) were shown to be already induced in freshwaters when tested, respectively, with the inducers isopropyl-beta-D-thiogalactopyranoside and methyl-beta-D-glucuronide. Both enzymatic activities were compared, respectively, with plate counts of total and faecal coliforms in freshwaters. Enzymatic methods and reference plate counts were significantly correlated in log-log plots. Moreover, the GLUase method allowed the detection of viable (presenting a detectable GLUase activity) but nonculturable Escherichia coli.

Bacteriological Techniques↗
PubMed2000

Identification of a human epitope in hepatitis C virus (HCV) core protein using a molecularly cloned antibody repertoire from a non-symptomatic, anti-HCV-positive patient.

Healthy carriers of hepatitis C virus (HCV) infection exhibit a specific antibody response against all HCV antigens, which could play a role in disease control. Generation of panels of human antibodies may permit a thorough characterization of this response and further identify particular antibodies with potential clinical value. To this effect, we have established a human phage-display antibody library from a patient exhibiting a high antibody response against HCV antigens and no clinical symptoms of disease. This library was screened against a recombinant core antigen [amino acids (aa) 1-119] produced in E. coli. Two recombinant Fab-carrying phages (rFabCs) were isolated and characterized. Both rFabC3 and rFabC14 recognize aa 1-48 on core antigen, but rFabC14 is competed out by a synthetic peptide, C(2-20) (aa 1-20), at much lower concentrations than rFabC3. In order to identify more precisely the recognition sites of these antibodies, we produced soluble forms of the rFabs (sFabs), and used them to pan a random phage-display peptide library. A single peptide sequence, QLITKPL, was identified with sFabC3, while two equally represented sequences, HAFPHLH and SAPSSKN, were isolated using sFabC14. The QLITKPL sequence was partially localized between aa 8 and 14 of core protein, but no clear homology was found for the two sFabC14 peptides. However, we confirmed the specificity of these peptides by competition experiments with sFabC14.

Adult↗
PubMed2000

Proton magnetic resonance spectroscopy of the medial prefrontal cortex in patients with deficit schizophrenia: preliminary report.

OBJECTIVE: Proton magnetic resonance spectroscopy (1H-MRS) was used to study medial prefrontal metabolic impairments in schizophrenic patients with the deficit syndrome. METHOD: The subjects were 22 schizophrenic patients categorized as deficit (N=5) or nondeficit (N=17) and 21 healthy subjects. (1)H-MRS was performed for the right and the left medial prefrontal cortex. RESULTS: The patients with the deficit syndrome had significantly lower ratios of N-acetylaspartate to creatine plus phosphocreatine than did the healthy subjects or nondeficit patients. CONCLUSIONS: As N-acetylaspartate levels could reflect neuronal density and/or viability, this finding suggests a neuronal loss in the medial prefrontal cortex of deficit patients.

Aspartic Acid↗
PubMed2000

Double blind randomized clinical trial examining the efficacy of bupivacaine suprascapular nerve blocks in frozen shoulder.

OBJECTIVE: To determine whether the pain, contracture, and disability associated with idiopathic frozen shoulder are diminished by a series of 3 indirect bupivacaine suprascapular nerve blocks delivered in an ambulatory care clinic. METHODS: A double blind randomized controlled trial of patients referred by primary care and specialty clinics in Montreal to an ambulatory tertiary care academic facility. Patients and controls underwent a series of 3 indirect suprascapular nerve blocks at 7 day intervals using either 10 c.c. bupivacaine 0.5 (Marcaine) in the treatment group or 10 c.c. of physiological saline in controls. Subjects in both groups were taught a program of shoulder range of motion exercises to be done at home. The primary outcome measure was the McGill-Melzack Pain Questionnaire (MPQ) short form at 1 month post-randomization (2 weeks after last injection). The secondary outcome measures were disability measured by the simple shoulder test and glenohumeral joint contracture measured by shoulder range of motion measurements. RESULTS: Thirty-four subjects were randomized from 58 screened. Average age of subjects was 52 years. Mean duration of pain prior to randomization was one year. Dropout rate was 11% in the treatment group, 30% in the placebo group. A 64% reduction in pain in the treatment group versus 13% in the placebo group was observed at one month as measured by the MPQ multidimensional pain descriptors score (p = 0.03). A nonsignificant 15.8% improvement in shoulder function in the treatment group versus 4% in the placebo group (p = 0.24) was also noted. No improvement in shoulder range of movement was noted. No side effects other than transient vagal symptoms and local tenderness at the injection site were reported. CONCLUSION: The use of bupivacaine suprascapular nerve blocks was effective in reducing the pain of frozen shoulder at one month. Clinical studies with a larger number of subjects and a longer study period will help determine the duration and nature of the effect of bupivacaine suprascapular nerve blocks in treating the pain, disability, and glenohumeral joint contracture of frozen shoulder.

Adult↗