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Biomedical subjects

M Petit

Publications and source records attributed to M Petit.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2000

Survival of Escherichia coli in freshwater: beta-D-glucuronidase activity measurements and characterization of cellular states.

A rapid enzyme assay measuring beta-D-glucuronidase activity of Escherichia coli was tested in survival experiments after discharge of E. coli in river water. Enzyme activity was compared with several analyses performed to characterize cellular states under stressful conditions. Enzyme activity remained stable under starvation and light stress conditions despite losses of culturability, respiratory activity, and cytoplasmic membrane integrity. beta-D-Glucuronidase activity followed the pattern of genetic and morphologic cell integrity. The tested enzyme assay seems well adapted to study the fate of fecal coliforms in survival experiments, and appears to be a rapid and efficient way to estimate the microbiological quality of surface waters.

Bacteriological Techniques↗
PubMed1999

Linkage disequilibrium on the COMT gene in French schizophrenics and controls.

Catechol-O-methyltransferase (COMT) catalyzes the degradation of catecholamines and could therefore play a role in the etiology of schizophrenia. Moreover, microdeletions including the COMT locus have been found in schizophrenics presenting typical features of the velo-cardio-facial syndrome. In the present work, five single-strand conformation polymorphisms were detected in exons of the COMT gene. The linkage disequilibria between the polymorphisms were estimated, and the genotypic frequencies were calculated on a sample of 126 to 137 schizophrenics and 136 to 140 controls, depending on the marker. Patients and controls were matched for ethnicity and geographical origin. A trend toward association was found between schizophrenia and (i) genotype 11 of the Pml I polymorphism (p = 0.034; OR = 1.82); (ii) haplotype 1-2 for the Pml I and Bcl I polymorphisms (p = 0.022; OR = 1.75). The Pml I polymorphism is in complete linkage disequilibrium with the common Met-->Val(158) substitution, which affects the activity of the enzyme. This finding suggests a possible minor effect of COMT in a multifactorial threshold model of vulnerability to schizophrenia.

3' Untranslated Regions↗
PubMed1999

Direct repair of spondylolysis without spondylolisthesis, using a rod-screw construct and bone grafting of the pars defect.

STUDY DESIGN: A retrospective study of patient outcome after pars repair using an original technique in patients with spondylolysis without spondylolisthesis and degenerative disk disease. OBJECTIVES: To assess the results of a new technique of internal fixation that avoids penetration of the spinal canal, temporary fixation of the lumbosacral junction, and postoperative bracing owing to stable instrumentation consisting of pedicle screws and a V-shaped rod resting against the inferior aspect on the spinous process and the posterior aspects of the laminas. SUMMARY OF BACKGROUND DATA: Previously described techniques for direct repair of a pars defect often require postoperative bracing and can require intracanal penetration of wires or hooks; screws passing directly through the defect, thereby lessening the bone surface available for bone grafting; and temporary fixation of the lumbosacral junction with a plate that must be removed. METHODS: Patients with painful pars defect not responding to conservative therapy and interfering with everyday life, sports, or work were considered to be eligible for direct repair of the spondylolysis rather than lumbosacral fusion, if there was no associated degenerative disk disease or spondylolisthesis. The surgical technique involves placement of screws on the pedicles of the involved vertebra and the fixation of the loose posterior arch with a solid rod bent in a V shape, taking purchase on the spinous process and laminas. A bone graft is placed under compression in the pars defect before the rod-screw construct is tightened. RESULTS: The first 10 patients who underwent this technique had an average follow-up of 35 months (range, 7 months to 5.3 years); mean age at operation was 26 years (range, 16-48 years). Six patients had an excellent result, returned to normal everyday life and work, and participated in sports when desired. The outcome in one patient was rated good and in one, fair. The procedure in one was considered a failure, although bone fusion seemed to have been obtained. Seven patients would recommend the operation, one would hesitate. No complications were encountered because of the specific design of the construct. CONCLUSIONS: This new technique offers the advantage of being easy and fast, it can be performed using a great number of available spinal instrumentations using rods and pedicle screws. There is no violation of the neural canal except in the case of a misplacement of pedicle screws. No postoperative brace was used, return to everyday life avoiding low back stress was immediate, and return to work or sports was possible 3 to 6 months after the procedure. This technique seems safe and effective but needs careful selection of patients, as do all other techniques for direct repair of pars interarticularis.

Adolescent↗
PubMed1999

Does storage affect epifluorescence microscopic counts of total bacteria in freshwater samples?

Preservation with formalin and storage at 4 degrees C of freshwater samples, associated with sonication before counting, proved to be efficient for a few days of storage (no differences with the initial cell count within 7 d of storage); after 8 months, 95% of the initial count was preserved. This procedure always gave higher counts than those obtained from the freezing technique of filter storage at -18 degrees C after sample filtration.

Cold Temperature↗
PubMed1999

Month of birth in deficit and non-deficit schizophrenic patients.

In order to test the hypothesis that an excess of summer births is a risk factor for deficit syndrome, the month of birth was studied in 53 deficit schizophrenic patients compared to 158 non-deficit patients. No significant difference in terms of month of birth or season of birth was observed between deficit and non-deficit patients, suggesting that summer births might not be a risk factor for deficit schizophrenia.

Adult↗
PubMed1999

Apolipoprotein E-varepsilon4 frequency in deficit schizophrenia.

The apolipoprotein E (ApoE) genotype has been found to affect the expression of several neuropsychiatric disorders. We determined ApoE genotype frequencies and their relationship to primary negative symptoms in 61 non-deficit and 45 deficit schizophrenic patients, and compared them with 98 control subjects. No difference was observed when genotype or allele frequencies were compared between the three groups. Our data do not support a role for ApoE in the phenotypic expression of schizophrenia.

Adult↗
PubMed1999

Effects of cellulose derivatives and additives in the spray-drying preparation of acetaminophen delivery systems.

Microcrystalline cellulose (MCC), sodium carboxymethylcellulose (NaCMC), hydroxypropylmethylcellulose (HPMC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), and ethylcellulose (EC) were used for the production of time-controlled acetaminophen delivery systems using a spray-drying technique. The influence of factors such as polymer concentration, inlet temperature, and drug/polymer ratio were investigated. The product yields were a function of the type and concentration of the polymer, with the highest values being reached from feeds containing 1% MCC and EC. Parameters of 1% polymer concentration and an inlet temperature of 140 degrees C gave rise to optimal processing conditions. Using these parameters, the influence of some adjuncts, such as polyethylene glycol 6000 (PEG 6000), dibutyl sebacate (DBS), polyvinylpyrrolidone (PVP), and carboxylic acids such as citric acid (CA), phthalic acid (PA), succinic acid (SA), tartaric acid (TA), and oxalic acid (OA), on the spray-drying process was evaluated. Of the additives tested, PVP (with MCC), DBS (with EC), and PEG 6000 (with NaCMC) induced yield decreases from 70% to 49%, 66% to 39%, and 37% to 17%, respectively. As for carboxylic acids (with NaCMC), similar or better performances of 43%, 45%, 47%, and 49% were obtained with SA, OA, PA, and TA, respectively. Dissolution studies in pH 1 dilute HCl and pH 6.8 phosphate buffer dissolution media showed that formulations consisting of 1% polymer with a drug/polymer ratio of 1/1 exhibited the slowest drug release, with the spheroids coated with NaCMC and HEC showing the longest T50% values (with 45 and 53 min at pH 1 and 49 and 55 min at pH 6.8, respectively). Slightly better sustained drug release in pH 6.8 dissolution medium was reached, showing the following trend: HEC > NaCMC > MCC > EC > HPMC. Concerning the additives, the trends in dissolution T50% of drug revealed TA > SA > CA > OA > PVP > PA > DBS in acidic pH 1 dissolution medium and PVP > OA > TA > SA > PA > CA > DBS in phosphate buffer at pH 6.8.

Acetaminophen↗
PubMed1998

Anticipation in schizophrenia: no evidence of expanded CAG/CTG repeat sequences in French families and sporadic cases.

A decrease in age of onset of schizophrenia through consecutive family generations (anticipation) has been found in several studies. Anticipation is known to result from expansion of CAG repeats in genes that determine several neurodegenerative disorders. In a previous study we analysed 26 unilineal two-generation French pedigrees and found clinical evidence of anticipation. A 10-year mean reduction in age of onset of schizophrenia was found in the second generation compared with the parental generation. The repeat expansion detection method was used to screen for CAG expansion in 21 of the 26 families with evidence of anticipation for the disease and in 59 sporadic schizophrenics and 59 controls. Comparison of the frequency distributions of CAG/CTG repeat size observed in schizophrenics and controls showed no significant difference, even when we considered familial (P = 0.23) and sporadic (P = 0.25) affected individuals separately. These results do not support the association between long CAG repeats and schizophrenia. However, the possibility that expansions with fewer than 40 repeats are involved in schizophrenia cannot be excluded.

Adult↗
PubMed1998

No association of apolipoprotein epsilon 4 allele with schizophrenia even in cognitively impaired patients.

Given the strong association of the apolipoprotein E (apoE) allele epsilon 4 (epsilon 4) with Alzheimer's disease or cognitive decline in elderly, we tested whether cognitive performance in schizophrenic subjects is associated with an increase in the frequency of the ApoE epsilon 4 allele. Our data indicate that in our sample: (1) there is no association between schizophrenia and the ApoE epsilon 4 allele; and (2) the ApoE epsilon 4 allele is not of major importance with regard to the cognitive decline observed in schizophrenia.

Adult↗