Biomedical subjects

G Poirier

Publications and source records attributed to G Poirier.

At least 19 recordsLinked to original sources

PubMed2001

Restless Legs Syndrome: scoring criteria for leg movements recorded during the suggested immobilization test.

Objective: To evaluate the characteristics of leg movements experienced by patients with the restless legs syndrome (RLS) during wakefulness using the suggested immobilization test (SIT).Methods: Forty patients with primary RLS who showed an index of leg movements greater than 40 during the SIT were selected for these analyses.Results: In general, Coleman's criteria for scoring PLMS were appropriate for scoring leg movements during the SIT. However, a substantial number of leg movements lasted between 5 and 10 s, exceeding Coleman's maximum duration criterion. The other criteria used to score PLMS (i.e. movements separated by 4-90 s and occurring in series of four consecutive movements) allowed detection of more than 90% of all leg movements recorded during the SIT. The distribution of inter-movement intervals (IMI) suggests that a great majority of leg movements recorded during the SIT are periodic, with a modal value of IMI between 11-12 s.Conclusion: Considering that leg movements recorded during the SIT last longer than those occurring during sleep, we recommend using a duration criterion of 0.5-10 s for scoring the former. We also recommend using the same periodicity criteria for the SIT as those used for scoring PLMS.

Journal Article↗

PubMed2001

Rhythmic masticatory muscle activity during sleep in humans.

Rhythmic Masticatory Muscle Activity (RMMA) is frequently observed during sleep in normal subjects and sleep bruxers. We hypothesized that some normal subjects exhibit RMMA at a lower frequency than sleep bruxers. Polysomnographic data from 82 normal subjects were compared with data from 33 sleep bruxers. RMMA episodes were defined as three or more consecutive bursts of masseter EMG activity, with or without tooth-grinding. Such episodes were observed in nearly 60% of normal subjects. A lower frequency of episodes was noted in normal subjects than in bruxers. Sleep organization was similar between groups. Bruxers had twice as many masseter muscle bursts per episode and episodes of higher amplitude compared with controls with RMMA. The high prevalence of RMMA observed in normal subjects suggests that this activity is related to certain sleep-related physiological functions, including autonomic activation.

Adolescent↗

PubMed2000

Excretion of volatile nitrosamines in a rural population in relation to food and drinking water consumption.

Urinary excretion of volatile nitrosamines was assessed in 59 non-smokers living in a rural county of Québec, Canada. Water and food intakes were measured by means of a 24-hour recall. Nitrates were analyzed in the tap water of all participants (geometric mean=2.0 mg nitrate-N/L) and dietary intakes of nitrate and vitamins C and E were estimated via a validated Canadian food database. Urine was collected over the same 24-hour period and analyzed for nitrates by hydrazine reduction and for volatile nitrosamines by gas-chromatography/mass spectrometry. N-Nitrosopiperidine (NPIP) was found in urine samples from 52 of the 59 subjects. Geometric mean of NPIP urinary excretion was 67 ng/day and maximum value was 1045 ng/day. No other volatile nitrosamine was detected. There was a correlation between urinary nitrate excretion and total nitrate intake (r=0.71, P < 0.001). However, no relationship was found between urinary NPIP excretion and either nitrate excretion, dietary or water nitrate intakes. NPIP excretion was significantly correlated to coffee intake (r=0.40, P=0.002) and this relation was not modified by vitamin intake. We conclude that nitrate intake is not related to nitrosamine excretion in this rural population. The influence of coffee consumption on NPIP excretion deserves further attention.

Adult↗

PubMed1999

Binding capacity of various fibre to pesticide residues under simulated gastrointestinal conditions.

The purpose of this study was to compare the effect of the nature and quantity of various dietary fibre (cellulose, hemicellulose, pectin, lignin) in diets on the binding capacity to pesticides azinphos-methyl (AZM), chlorpropham (CLP), chlorothalonil (CKL), permethrin (PER) as estimated by solubility under conditions of pH and temperature simulating those in the gastrointestinal tract (incubated at pH 2 for 30 min at 37 degrees C, then at pH 7 for 60 min). The ratios of fibre to pesticides were determined in omnivorous diets. In this model, the binding capacity of lignin was equal to hemicellulose for PER, AZM and CLP, but it was significantly higher for CKL. Hemicellulose bound more CKL, AZM and CLP than did cellulose. Although pectin appreciably decreased all pesticides, its effect was lower than other fibres with one exception--cellulose-CKL. In the presence of equal amounts of fibre, lignin exerted the most significant effect on pesticide solubility. Hemicellulose and cellulose bind to the same extent PER and AZM. The effect of pectin was significant only on CKL and AZM when compared to the control.

Adult↗

PubMed1997

Specific cleavage of the large subunit of replication factor C in apoptosis is mediated by CPP32-like protease.

Recent evidence suggests that the growing family of cysteine proteases related to the interleukin-1beta-converting enzyme (ICE) is of central importance in mediating apoptosis. Proteolytic cleavage of a small group of cellular substrates by these enzymes in association with the onset of apoptosis has been reported. In the present study, we searched a protein data base for potential death substrates possessing the CPP32 cleavage site, DEVD, and identified several candidates including RFC140, the large subunit of replication factor C, which we subsequently demonstrated to be specifically cleaved in a variety of cell types undergoing apoptosis in response to different cytotoxic agents, whereas no degradation is observed in a cell line resistant to etoposide-induced apoptosis. The abrogation of RFC140 cleavage in apoptotic extracts by Ac-DEVD-CHO, a potent inhibitor of CPP32, together with the finding that a CPP32 consensus cleavage sequence, DEVD, exists in RFC140, suggests that CPP32 or a close relative is responsible for RFC140 degradation in apoptosis.

Animals↗

PubMed1997

Clinical, polysomnographic, and genetic characteristics of restless legs syndrome: a study of 133 patients diagnosed with new standard criteria.

One hundred thirty-three cases of restless legs syndrome (RLS), diagnosed with criteria recently formulated by an international study group, were studied by questionnaire and with all-night polysomnographic recordings. Results show that RLS starts at a mean age of 27.2 years and before age 20 in 38.3% of patients. Symptoms often appear in one leg only and also involve upper limbs in about half of all cases. Most patients (94%) report sleep-onset insomnia or numerous nocturnal awakenings due to RLS symptoms. A strong relationship was found between these complaints and polysomnographic findings; increasing sleep latency and number of awakenings and decreasing sleep efficiency were associated with worsening symptoms. Periodic leg movements in sleep (index > 5 movements/h sleep) were found in 80.2% of patients. This study shows that this percentage is increased when 2 recording nights are considered (most severe score). Eighty patients of 127 (63%) reported the presence of RLS in at least one of their first-degree relatives. In these families, 221 of 568 first-degree relatives (39%) were reported by the patients to be affected with RLS.

Adult↗

PubMed1996

Persistence of repetitive EEG arousals (K-alpha complexes) in RLS patients treated with L-DOPA.

Compared to normal control subjects, patients with primary restless legs syndrome (RLS) have an increased number of K-complexes, followed by bursts of electroencephalographic (EEG) alpha activity-together these are referred to as K-alpha complexes. In the present study, a large proportion of K-alpha complexes was found to be temporally associated with periodic leg movements in sleep. Because many K-alpha complexes precede the onset of movements, they cannot be considered secondary to the movements themselves. The persistence of K-alpha complexes after suppression of leg movements by means of L-DOPA further supports the hypothesis that these EEG events are a primary phenomenon. The results may have clinical implications because a large proportion of RLS patients complain of non-restorative sleep even after treatment with L-DOPA.

Adult↗

PubMed1995

The baculovirus p35 protein inhibits Fas- and tumor necrosis factor-induced apoptosis.

The baculovirus p35 gene product inhibits virally induced apoptosis, developmental cell death in Caenorhabditis elegans and Drosophila, and neuronal cell death in mammalian systems. Therefore, p35 likely inhibits a component of the death machinery that is both ubiquitous and highly conserved in evolution. We now show for the first time that p35 also inhibits Fas- and tumor necrosis factor (TNF)-induced apoptosis. Additionally, p35 blocks TNF- and Fas-induced proteolytic cleavage of the death substrate poly(ADP-ribose) polymerase from its native 116-kDa form to the characteristic 85-kDa form. This cleavage is thought to be catalyzed by an aspartate-specific protease of the interleukin 1 beta-converting enzyme family designated prICE (Lazebnik, Y. A., Kaufmann, S. H., Desnoyers, S., Poirier, G. G., and Earnshaw, W. C. (1994) Nature 371, 346-347). Our data suggest that p35 must directly or indirectly inhibit prICE. Given that p35 inhibits both TNF and Fas killing, along with previous reports of its ability to block developmental, viral, and x-irradiation-induced cell death, the present results indicate that TNF- and Fas-mediated apoptotic pathways must have components in common with these highly conserved death programs.

Antigens, Surface↗

PubMed1995

DNA base excision repair of 5-hydroxymethyl-2'-deoxyuridine stimulates poly(ADP-ribose) synthesis in Chinese hamster cells.

5-Hydroxymethyl-2'-deoxyuridine (hmdUrd) is incorporated into DNA as a thymidine analog resulting in extensive substitution of thymine residues with 5-hydroxymethyluracil (hmUra) residues. These hmUra residues are then subject to excision by action of hmUra-DNA glycosylase. 3-Aminobenzamide (3AB), an inhibitor of poly(ADP-ribose) synthesis, is toxic to cells that incorporate and repair hmdUrd. To demonstrate that incorporation and repair of hmdUrd stimulates synthesis of poly(ADP-ribose) from intracellular NAD, V79 hamster cells were treated with hmdUrd and intracellular NAD levels were measured. Following hmdUrd treatment, NAD levels fell markedly (80-90%) within 4 h and remained low for at least 10 h, before partially recovering by 24 h. The degree of NAD lowering was dose dependent and paralleled net hmdUrd incorporation. The NAD lowering was largely prevented by concurrent treatment with 4 mM 3AB. No effects on NAD levels were seen following treatment with deoxythymidine or bromodeoxyuridine, which are incorporated into DNA but, in contrast to hmdUrd, are not repaired. When the incorporation of hmdUrd into DNA was blocked with hydroxyurea or aphidicolin, no NAD lowering was seen. HmdUrd also did not produce lowering of NAD concentrations in mutant cell strains deficient in the ability either to incorporate hmdUrd into DNA or to repair hmdUrd from DNA. These results demonstrate that synthesis of poly(ADP-ribose) resulted directly from the incorporation into DNA of the nucleoside hmdUrd and its subsequent repair. These results unequivocally demonstrate that the initiation of normal DNA base excision repair by itself, and not DNA damage per se, is a sufficient stimulus for the induction of poly(ADP-ribose) synthesis.

Animals↗

PubMed1994

Discrimination between thymic epithelial cells and peripheral antigen-presenting cells in the induction of immature T cell differentiation.

During their intrathymic migration, immature CD4+ CD8+ thymocytes that express a TCR able to recognize the expressed MHC molecules are positively selected, i.e., complete their differentiation program and become mature T cells. Using the immature CD4+CD8+ T cell line DPK, which can be induced to differentiate in culture, we show here that a subset of isolated thymic epithelial cells, but not peripheral antigen-presenting cells, can induce differentiation, suggesting a unique function of these cells in T cell development. In addition, analysis of activation markers induced by thymic epithelial cells versus specific antigen gives the first direct evidence that positive selection is associated with low level cell activation. In contrast with strict affinity-avidity models of thymic selection, we propose that a specialized antigen-presenting cell environment is an essential contributor to TCR-mediated differentiation in the thymus.

Animals↗

PubMed1994

Island nurse.

Explore the source record for details and available documents.

Caribbean Region↗

PubMed1993

Birthing experience of adolescents at the Ottawa General Hospital Perinatal Centre.

OBJECTIVE: To study the experiences of prenatal care, prenatal classes and birthing among adolescents. DESIGN: Anonymous self-report questionnaire survey. SETTING: Ottawa General Hospital Perinatal Centre. PATIENTS: A total of 100 adolescents (aged less than 20 years) and 100 control subjects (aged over 19 years) who gave birth at the Perinatal Centre from June 1989 to August 1990. MAIN OUTCOME MEASURES: Prenatal experiences, attendance at prenatal classes, experiences in labour and delivery, postpartum care. RESULTS: Only 26% of the adolescent patients sought prenatal care in the first trimester, and only 27% attended prenatal classes, as compared with 87% and 91% of the control subjects (p < 0.001). Most of the adolescents felt uncomfortable in the same waiting room as adult women. During labour and delivery 50% of the adolescents had their mothers with them for support, whereas 83% of the adults had their husbands with them (p < 0.001). Over half (59%) of the adolescents stated that they were not prepared for labour and delivery, as compared with 26% of the adults (p < 0.001). Of the adolescents 85% opted to care for their babies after birth. CONCLUSION: Pregnant adolescents do not avail themselves adequately of the medical and psychosocial services available to them through the health care system. Our findings suggest features of prenatal clinics that would make them attractive and accessible to such patients.

Adolescent↗

PubMed1993

Expression in Escherichia coli of the 36 kDa domain of poly(ADP-ribose) polymerase and investigation of its DNA binding properties.

We have expressed in Escherichia coli the 36 kDa domain of the human poly(ADP-ribose) polymerase. This polypeptide comprises the C-terminal part of the DNA binding domain, as well as the automodification region of the enzyme, but lacks the zinc-finger motifs of the N-terminal region and the C-terminal catalytic domain. By probing the crude E. coli protein extracts with radioactive DNA probes (South-Western blots), we have shown that the 36 kDa domain binds a DNA probe of 222 bp but does not bind a shorter probe of 66 bp. This interaction is stronger when the polypeptide is fused to the 55 kDa catalytic domain of the enzyme.

Amino Acid Sequence↗

PubMed1993

Analysis of the cellular requirements for the binding of exogenous peptides to MHC class II molecules.

The cellular mechanism regulating the binding of exogenous peptides to MHC class II molecule is still an object of controversy. In order to study the cellular requirements of peptide binding we have set up an indirect fluorescence assay that enables us to detect quantitatively peptide/MHC class II complexes on the cell surface of the mouse B lymphoma A20. The absence of binding on several MHC class II-negative cell lines and the inhibition of binding in the presence of competitor peptides or in the presence of a polyclonal serum against MHC class II molecules confirmed the specificity of the assay. A panel of pharmacological and physical agents was then used to determine the mechanism of this regulation. Binding was not significantly affected by vinblastine or cycloheximide and was affected only to a small extent by chloroquine or azide. In contrast to the long half-life previously reported for soluble complexes, we found that the half-life of a peptide/MHC class II complex expressed on A20 was shorter than 3 hr, suggesting that peptide binding might be regulated at the cellular level. The energy of activation of peptide binding, estimated from the temperature dependence of the rate of peptide binding, was decreased above 27 degrees C, suggesting that enhanced peptide binding to MHC class II molecules might depend on the fluidity of the cell membrane lipids.

Adenosine Triphosphate↗

PubMed1993

Isolation and characterization of a new murine MHC class II transcription mutant cell line.

We have isolated and characterized a new MHC class II transcription mutant cell line, called UV. This cell line was derived from the mouse B lymphoma A20 by UV light-induced mutagenesis and immunoselection for the loss of surface MHC class II molecules. It expresses only 5% of the level of MHC class II molecules on A20 and this is associated with a similar reduction of class II specific mRNA. This defect cannot be restored by the MHC class II transcription inducers, IL-4 and IFN gamma, confirming that the mutation acts at the transcription level. The mutation also affects MHC class I expression, but the transcription of class I molecules is not affected. In contrast, the expression of other markers, such as the invariant chain and the surface immunoglobulins G and M, is not modified. Such a variant should prove useful for the study of the transcription factors involved in the regulation of MHC class II expression.

Animals↗

PubMed1993

Few peptides dominate cytotoxic T lymphocyte responses to single and multiple minor histocompatibility antigens.

Minor histocompatibility (H) antigens are T cell recognized self proteins which can cause graft versus host disease or organ transplant rejection. We have analysed the number of peptide epitopes involved in cytotoxic T lymphocyte (CTL) responses to single or multiple minor H antigens. Bulk CTL responses were generated in H-2b mice differing in one (H-1), two (H-1 and H-25), or multiple (> 29) minor H loci, and HPLC separation was used to analyse the complexity of CTL recognized peptides. Anti-H-1 CTL recognize one out of 50 HPLC peptide fractions and recognition is H-2Kb restricted. The same peptide fraction is also recognized by anti-H-1/H-25 CTL and no additional epitopes are detected, indicating that the H-25 locus does not stimulate CTL when combined with H-1. CTL generated to multiple minor H loci (including H-1 and H-25) recognize two HPLC peptide fractions which are presented by H-2Db and H-2Kb class I molecules, respectively. The H-2Kb presented fraction is the same as that recognized by anti-H-1 and anti-H-1/H-25 CTL, and it is shown to contain a H-1-derived peptide. Subfractionation of the CTL recognized HPLC fractions is consistent with the presence of only one peptide epitope. Thus, in the responses analysed here one minor H locus encodes probably only one CTL epitope. The study provides a molecular explanation for immunodominance among minor H antigens, suggesting that dominant loci encode single peptide epitopes which are presented efficiently by MHC class I molecules enabling them to readily stimulate CTL responses.

Animals↗

PubMed1993

French Renaissance travel accounts: images of sin, visions of the New World.

Accounts of French Renaissance travels to America reveal how Europeans described a newly discovered "Other," and, indirectly, the "Self." Guy Poirier analyzes in his article how the images of acts against nature and prodigies could, at the same time, be linked to a European "épistémè" and construct an ideological discourse of their own.

Christianity↗

PubMed1991

Association of poly(ADP-ribose) polymerase with the nuclear matrix: the role of intermolecular disulfide bond formation, RNA retention, and cell type.

The recovery of the enzyme poly(ADP-ribose) polymerase (pADPRp) in the nuclease- and 1.6 M NaCl-resistant nuclear subfraction prepared from a number of different sources was assessed by Western blotting. When rat liver nuclei were treated with DNase I and RNase A followed by 1.6 M NaCl, approximately 10% of the nuclear pADPRp was recovered in the sedimentable fraction. The proportion of pADPRp recovered with the residual fraction decreased to less than 5% of the total nuclear polymerase when nuclei were prepared in the presence of the sulfhydryl blocking reagent iodoacetamide and increased to approximately 50% of the total nuclear pADPRp when nuclei were treated with the sulfhydryl cross-linking reagent sodium tetrathionate (NaTT) prior to fractionation. To determine whether this effect of disulfide bond formation was unique to rat liver nuclei, nuclear matrix/cytoskeleton structures were prepared in situ by sequentially treating monolayers of tissue culture cells with Nonidet-P40, DNase I and RNase A, and 1.6 M NaCl (S.H. Kaufmann and J.H. Shaper (1991) Exp. Cell Res. 192, 511-523). When nuclear monolayers were prepared from HTC rat hepatoma cells, CaLu-1 human lung carcinoma cells, and CHO hamster ovary cells in the absence of NaTT, pADPRp was undetectable in the nuclease- and 1.6 M NaCl-resistant fraction. In contrast, when nuclear monolayers were isolated in the presence of NaTT, from 5% (CaLu-1) to 26% (HTC cells) of the total nuclear pADPRp was recovered with the nuclease- and salt-resistant fraction. Examination of these residual structures by SDS-polyacrylamide gel electrophoresis under nonreducing conditions suggested that pADPRp was present as a component of disulfide cross-linked complexes. Further analysis by immunofluorescence revealed that the pADPRp was diffusely distributed throughout the CaLu-1 or CHO nuclear matrix. In addition, when matrices were prepared in the absence of RNase A, pADPRp was also observed in the residual nucleoli. These observations reveal that the recovery of pADPRp with a nuclease- and salt-resistant nuclear subfraction is dependent on the source of the nuclei and on the conditions used to fractionate those nuclei. In addition, these observations raise the possibility that there might be different functional classes of pADPRp molecules within the nucleus.

Animals↗