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Biomedical subjects

J Mathieu

Publications and source records attributed to J Mathieu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Anesthetic and surgical complications in 219 cases of myotonic dystrophy.

The objective of this study was to assess the frequency, type, and severity of perioperative complications after a first surgery under general anesthesia in patients with myotonic dystrophy (DM) and to measure the association with suspected risk factors. Numerous cases of perioperative complications in DM patients have been reported. Hazards have been associated with the use of thiopentone, suxamethonium, neostigmine, and halothane. A retrospective study of perioperative complications was conducted for 219 DM patients who had their first surgery under general anesthesia at the Chicoutimi Hospital. The overall frequency of complications was 8.2% (18 of 219). Most complications (16 of 18) were pulmonary, including five patients with acute ventilatory failure necessitating ventilatory support, four patients with atelectasis, and three patients with pneumonia. Using multivariate analysis, we found that the risk of perioperative pulmonary complications (PPC) was significantly higher after an upper abdominal surgery (odds ratio (OR), 24.4; 95% CI, 4.0 to 149.3) and for patients with a severe muscular disability, as assessed by the presence of proximal limb weakness (OR, 14.1; 95% CI, 1.5 to 134.4). The likelihood of PPC was not related to any specific anesthetic drug. Because of the increased risk of PPC, careful monitoring during the early postoperative period, protection of upper airways, chest physiotherapy, and incentive spirometry are mandatory in all symptomatic DM patients, particularly those with a severe muscular disability or those who have undergone an upper abdominal surgery.

Adolescent↗
PubMed1996

Alzheimer's disease: preliminary study of spatial distribution at birth place.

Alzheimer's disease (AD) is a neurodegenerative disorder which is characterized by a progressive loss of memory and the alteration of cognitive functions. At least three chromosomal segments have been associated with early-onset AD in genetic linkage studies. These results argue for a certain degree of heterogeneity in the genetic origin of some forms of AD, although environmental risk factors cannot be ruled out in late-onset AD. In this preliminary study, we analyzed the geographical distribution of the birth places of a sample of 235 AD cases born in a defined region of Quebec (Canada), between 1895 and 1935. We wished to test the hypothesis that risk factors acting at, or around birth place and time play a role in the etiology of AD. The field of study was divided into rural and urban areas. A reference population of live births was used to compute a measure of odds ratio (OR). The OR results showed a statistically significant excess of AD cases in the rural area as compared to the reference population. When stratified for sex, the OR results showed a global excess of female AD cases in both the rural and the urban areas. For men, only the urban area presented a statistically significant deficit. We also analyzed the structures of the genealogical kinships of the rural and urban sub-groups. Although AD cases from the rural sub-group were more closely related to each other than those from the urban one, removal of the kin pairs from the OR analysis seemed to have little effect on the rural/urban distribution of cases. Therefore, the OR results would not appear to be due primarily to a difference in the kinship structures of the two sub-groups. This could mean that some risk factors for AD afflict women more strongly than men, the effect being different depending on the urban or rural origin. However, potential biases such as a higher rate of report for women, differential migration between birth places or a differential mortality ratio between sexes could produce spurious results in the direction of what we have observed in this preliminary study.

Aged↗
PubMed1996

Season of birth and Alzheimer's disease: a population-based study in Saguenay-Lac-St-Jean/Québec (IMAGE Project).

The birth distribution of 399 cases of Alzheimer's disease (AD) identified in the region of Saguenay-Lac-St-Jean (Québec) was compared with that of: (a) the population currently living in the area; and (b) the population born during the same period in the same area. AD cases have been recruited since 1986 by the IMAGE Project. Cases and controls were grouped according to the month of birth and according to the day of birth using density estimation. Analyses showed a significant deficit of births in the month of May. We believe these preliminary results deserve further attention and we suggest two possible explanations that could lead to a deficit of AD births at specific periods during the year.

Aged↗
PubMed1996

Epidemiological study of reptured intracranial aneurysms in the Saguenay-Lac-Saint-Jean region (Quebec, Canada).

BACKGROUND: Using a population-based register of the Saguenay-Lac-Saint-Jean region (Quebec, Canada), the genealogical reconstruction of 533 individuals with intracranial aneurysm (IA) showed a familial aggregation (the presence of aneurysm in two or more first- to third-degree relatives) for 159 (29.8%) of them; this proportion is much higher than reported elsewhere. OBJECTIVE: As part of an ongoing project to assess a genetic predisposition to intracranial aneurysms in the Saguenay-Lac-Saint-Jean population, the objective of the present study was to determine whether age-specific rates of reputed cerebral aneurysms were higher than in other populations. DESIGN: A retrospective study of cases of proven ruptured IAs which were hospitalized during the 1973 to 1992 period was conducted. Age-adjusted rates were computed and compared to those reported in the Helsinki population. RESULTS: We identified 412 cases of ruptured aneurysms. The age-adjusted incidence rate was 7.2/100,000/year (6.2 for men, 8.1 for women), which is similar to the incidence rates reported in other studies. Although the mean age at time of rupture was younger (46.6 years +/- 13.8) than usually reported, no increase in age-specific incidence rates was detected. CONCLUSIONS: The results of this epidemiological study neither support nor reject the hypothesis of a genetic predisposition to intracranial aneurysms in the Saguenay-Lac-Saint-Jean population.

Adolescent↗
PubMed1996

Specific pathological Tau protein variants characterize Pick's disease.

Pick's disease (PiD) is characterized by a pan-laminar frontotemporal cortical atrophy, widespread degeneration of the white matter, chromatolytic neurons, and Pick bodies (PB). Microtubule-associated Tau proteins are the main cytoskeletal components modified during the neurodegenerative changes. In the present study, pathological alterations of Tau proteins were investigated in the brains of five PiD cases at both neuropathological and biochemical levels, using the monoclonal antibody AD2 which recognizes a phosphorylation-dependent Tau epitope and strongly labeled PB. A large number of cortical and subcortical regions were studied on frozen materials. Tau proteins were analyzed on mono- and two-dimensional gel electrophoreses using a quantitative western blot approach. In all specimens, a 55 and 64 kDa Tau doublet was observed in limbic, frontal, and temporal cortices as well as in striatum and substantia nigra. In contract, Alzheimer's disease (AD) brains are characterized by the presence of the 55, 64, and 69 kDa Tau triplet whereas the 64 and 69 kDa doublet is more typical of the progressive supranuclear palsy and corticobasal degeneration. Thus, the 55 and 64 kDa doublet appears to be specific to PiD, less acidic than AD Tau proteins, and well correlated with the presence of PB.

Aged↗
PubMed1996

A study of inbreeding and kinship in intracranial aneurysms in the Saguenay Lac-Saint-Jean region (Quebec, Canada).

The genealogies of 533 individuals with an intracranial aneurysm (IA) born in the Saguenay-Lac-Saint-Jean region, a geographically isolated area located in northeastern Quebec, were reconstructed using a population-based register. A control group consisting of three individuals of the same sex and born on the same day and in the same municipality than the IA patients was created; the genealogies of the 1599 controls were also reconstructed. The coefficients of inbreeding and kinship were calculated. Familial aggregation, i.e. the presence of IA in two or more first- to third-degree relatives, was also sought. The mean inbreeding coefficient was lower in the IA group than in the control group (7.92 x 10(-4) versus 10.04 x 10(-4)). The mean kinship coefficient was higher in the IA group than in the control group (2.17 x 10(-4) versus 1.55 x 10(-4)). Forty-eight IA patients (9.0%) were first-degree relatives compared to only 1.9% of the control individuals. The proportion of individuals showing familial aggregation was higher in the IA group than in the control group (29.8% and 18.6% respectively). These results strongly suggest that some IA are genetically determined in this population.

Consanguinity↗
PubMed1996

The gene responsible for a severe form of peripheral neuropathy and agenesis of the corpus callosum maps to chromosome 15q.

Peripheral neuropathy with or without agenesis of the corpus callosum (ACCPN) is a devastating neurodegenerative disorder that is transmitted as an autosomal recessive trait. Genealogical studies in a large number of affected French Canadian individuals suggest that ACCPN results from a single founder mutation. A genomewide search using 120 microsatellite DNA markers in 14 French Canadian families allowed the mapping of the ACCPN gene to a 5-cM region on chromosome 15q13-q15 that is flanked by markers D15S1040 and D15S118. A maximum two-point LOD score of 11.1 was obtained with the marker D15S971 at a recombination fraction of 0. Haplotype analysis and linkage disequilibrium support a founder effect. These findings are the first step in the identification of the gene responsible for ACCPN, which may shed some light on the numerous conditions associated with the progressive peripheral neuropathy or agenesis of the corpus callosum.

Agenesis of Corpus Callosum↗
PubMed1996

[Oxidative stress and apoptosis].

Programmed cell death or apoptosis is a process characterized by several morphological, biochemical and molecular events in response to physiological or pathological stimuli, such as gamma radiation. Free radicals being involved in many physiological and pathological processes, the aim of this study is to investigate the literature about the involvement of oxidative pathway during apoptotic process. As reported by several authors, the literature is abundant in this field and show the complexity of the network in which numerous molecules can regulate cell death and proliferation. However, reactive oxygen intermediate species (ROls) seem to play an important role in the induction of apoptosis as underlined by several reports. Regulation of cellular redox status may appear to be a key component which determines cell proliferation or apoptosis.

Animals↗
PubMed1996

Radiation-induced apoptosis in thymocytes: inhibition by diethyldithiocarbamate and zinc.

Apoptosis is a process of physiological cell death characterized by DNA fragmentation, chromatin condensation, loss of membrane asymmetry, mitochondrial alterations and cell lethality. In the present study, apoptosis induced in thymocytes by gamma irradiation is evaluated by flow cytometry, by a diphenylamine colorimetric method and by gel electrophoresis. Treatment of thymocytes with diethyldithiocarbamate or zinc shows that these compounds can inhibit radiation-induced apoptosis. Moreover, a synergistic effect is observed by using combinations of both compounds: ZnSO4 potentiates the effect of diethyldithiocarbamate at concentrations at which the compounds used separately show a low efficacy. A study of kinetics shows that addition of 1 microM diethyldithiocarbamate + 50 microM ZnSO4 (the most efficient combination) after irradiation can decrease DNA fragmentation even when it is added 2-3 h after irradiation. However, 1 microM diethyldithiocarbamate + 50 microM ZnSO4 cannot prevent the radiation-induced loss of membrane asymmetry and the decrease in alteration of the mitochondrial membrane as measured by binding of merocyanine 540 and uptake of rhodamine 123, respectively.

Acetylcysteine↗
PubMed1995

Intra- and inter-subject variabilities of CGP 33101 after replicate single oral doses of two 200-mg tablets and 400-mg suspension.

PURPOSE: The purpose of this study was to use a replicate designed trial to assess the overall, intra- and inter-subject variabilities in pharmacokinetic parameters of CGP 33101 after oral administration of tablets relative to that of powder suspended in water, and to determine the relative proportion of the intra-subject variance to the overall variability. METHODS: Sixteen healthy subjects were randomly assigned to four groups to receive tablets and suspension twice in four different treatment sequences. The plasma concentration-time profile of CGP 33101 was characterized in terms of Cmax, Tmax, and AUC. Bioavailability of tablets relative to suspension and intra- and inter-subject variability were assessed by statistical analysis. RESULTS AND CONCLUSIONS: The overall variabilities in absorption kinetics of CGP 33101 in healthy subjects were small with CV's of the population mean values for AUC and Cmax less than 26% for both tablets and suspension. Contribution of intra-subject variability to the overall variability was also small (approximately 20%). Both the overall and intra-subject variabilities of AUC and Cmax after suspension were larger than after the tablets. However, the differences in variability between tablets and suspension were not statistically significant (p > 0.05). The tablet formulation was bioequivalent to suspension in terms of rate and extent of absorption based on 90% conventional confidence intervals (for AUC and Cmax) and Wilcoxon rank-sum test (for Tmax).

Administration, Oral↗
PubMed1995

Ventilatory and locomotory activities in anoxia and subsequent recovery of epigean and hypogean crustaceans.

Locomotory and ventilatory responses to severe hypoxia and subsequent recovery were investigated in 3 amphipod crustaceans: 2 hypogean species (1 interstitial species Niphargus rhenorhodanensis and 1 karstic species N. virei) and 1 epigean species (Gammarus fossarum), and in an epigean population of 1 isopod crustacean (Asellus aquaticus). These species displayed respectively 46.7 h, 52.1 h, 6.3 h and 19.7 h lethal times for 50% of the population (LT50) values for anoxic survival. The aim of this study was to determine why the hypogean species displayed a survival time during severe hypoxia longer than that of Gammarus, Asellus and most other epigean crustaceans, and to better understand the ecological problems concerning Niphargus survival and perennation modalities in subterranean habitats which very often present hypoxic conditions during a hydrological cycle. The high resistance to severe hypoxia of hypogean animals partly results from an adaptation to the limitation of energetic expenditure linked to locomotion and ventilation in anaerobiosis, and from a decrease of general metabolism in severe hypoxia.

Animals↗
PubMed1995

DNA fragmentation induced in lymphocytes by gamma irradiation or dexamethasone: inhibition by diethyldithiocarbamate (DTC), potentiated by zinc.

Apoptosis is a process of physiological cell death characterized by DNA fragmentation, chromatin condensation, loss of membrane asymmetry and cell lethality. In the present study, apoptosis induced in thymocytes by dexamethasone or gamma irradiation is evaluated by flow cytometry, gel electrophoresis and other techniques. Treatment of thymocytes with DTC or zinc shows that these products can inhibit radiation- or dexamethasone-induced apoptosis. Moreover, a synergistic effect is observed by using associations of both products (5 microM DTC + 50 microM ZnSO4): ZnSO4 potentiates the effect of DTC at concentrations for which the molecules used separately show a low efficacy. These results indicate that DNA fragmentation induced by dexamethasone or irradiation in thymocytes share some identical mechanisms.

Animals↗
PubMed1994

Restoration of postburn impaired lymphocyte responsiveness by nonsteroidal anti-inflammatory drugs is independent of prostaglandin E2 inhibition.

Prostaglandin E2 (PGE2) has been implicated in postburn immunosuppression, which is responsible for septic complications. In the present work, seven non-steroidal anti-inflammatory drugs (NSAIDs), differing by their capacity to inhibit the cyclooxygenase pathway, were compared for their ability to restore T lymphocyte proliferative responses evaluated 4 days after thermal injury in rats. Salicylic acid, 5-aminosalicylic acid, and niflumic acid, given daily, fully restored spleen cell responses to concanavalin A (Con A) and phytohemagglutinin. These drugs were active only at doses that were below the anti-inflammatory doses and did not modify normal spleen cell responses. In these conditions, indomethacin slightly restored lymphocyte reactivity, whereas acetylsalicylic acid, ketoprofen, and piroxicam were ineffective. PGE2 production by Con A-stimulated spleen cells from untreated burned rats and after treatment with niflumic acid or 5-aminosalicylic acid did not correlate with the intensity of the proliferative response. Indomethacin, niflumic acid, and 5-aminosalicylic acid were added in vitro to spleen cells from normal and burned rats, at concentrations from 10(-7) to 10(-4) M. PGE2 production was strongly depressed by indomethacin and niflumic acid and not modified by 5-aminosalicylic acid. The proliferative response of normal spleen cells was depressed in a concentration-dependent manner by niflumic acid and slightly inhibited at the highest concentrations of indomethacin. In contrast, indomethacin concentration dependently restored the burn-impaired proliferative response, whereas niflumic acid further depressed it and 5-aminosalicylic acid had no effect. These results demonstrate that only some NSAIDs are able to restore T lymphocyte reactivity impaired after thermal injury and that this property is not related to inhibition of PGE2 production.

Administration, Oral↗
PubMed1994

Linkage disequilibrium analysis of childhood-onset spinal muscular atrophy (SMA) in the French-Canadian population.

Spinal muscular atrophy (SMA) is, after Duchenne muscular dystrophy, the most common neuromuscular disorder in childhood. The gene responsible for childhood SMA has been mapped to the q11.2-q13.3 region of chromosome 5. We have extended our linkage studies of SMA in the French-Canadian population to include microsatellite markers at the D5S125, D5S351, D5S435, JK53CA1/2 and MAP1B loci. These markers span about 4 cM of the SMA candidate region. We observed significant evidence for linkage between SMA and all the markers tested. The analysis of recombinant chromosomes provide evidence for the following genetic order: D5S125-D5S435-MAP1B-3'-JK53CA1/2 and places D5S351 proximal to JK53CA1/2. Furthermore, we confirm the current localization of the SMA gene distal to D5S435. Finally, we provide demonstration of significant linkage disequilibrium between childhood-onset SMA and four of the five marker loci, D5S125, D5S435, D5S351 and JK53CA1/2. Analysis of SMA-region haplotypes suggests that there may be a predominant SMA allele that is present on about 17% of SMA chromosomes in this sample of the French-Canadian population. We conclude that the observed linkage disequilibrium is likely due to genetic drift among regions of Quebec, consistent with this population's early history.

Age of Onset↗
PubMed1994

Recognition and elimination of senescent erythrocytes: implication of antibodies specific for malonic dialdehyde-protein adducts, as demonstrated by flow cytometry.

Many different hypotheses have been formulated about the mechanisms of specific recognition of senescent red blood cells (RBC). It is usually assumed that novel epitopes appear on RBC membranes during ageing and are responsible for recognition of aged RBC by antibodies, which is followed by binding to mononuclear phagocytes and then phagocytosis. But these age-related epitopes have not so far been identified. Lipoperoxidation is known to produce aldehydes, among which malonic dialdehyde (MDA). This dialdehyde reacts with primary amino groups of biological molecules, producing 1-amino-3-imino propene (AIP) bridges, and we had previously shown that sera of healthy mammals contain antibodies recognizing epitopes containing AIP bridges (AbAIP). Lipoperoxidation is responsible for many age-related damages in RBC membrane, and we tried in the present work to determine whether age-related epitopes responsible for recognition of aged RBC were not derived from lipoperoxidation. Using flow cytometry techniques, we demonstrated that some of the epitopes recognized by immunoglobulins which bind to aged RBC contain AIP bridges, and that some of these RBC-bound immunoglobulins are AbAIP. Consequently, AbAIP/AIP bridges interactions appear to play a role in recognition and elimination of senescent RBC.

Antibodies↗
PubMed1994

Immunization of mice with proteins reacted with malonic dialdehyde (MDA): comparison between autologous and heterologous modified proteins.

In previous experiments, rabbits were injected with heterologous proteins reacted with MDA, and produced antibodies cross-reacting with other MDA-modified proteins (MPr), but not with the corresponding native ones (Pr). It was concluded that these antibodies (AbAIP) recognized epitopes including 1-amino-3-imino-propene (AIP) bridges resulting from reactions of MDA with primary amino groups of proteins. In the present work, mice were injected with autologous MDA-modified albumin (MAI) or with heterologous MPr. Mice immunized with MAI developed an immune response leading to an increased production of AbAIP, which clearly indicates that such a response may occur even with an autologous MPr.

Animals↗
PubMed1993

Genetic epidemiology of autosomal recessive spastic ataxia of Charlevoix-Saguenay in northeastern Quebec.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a disorder that has an elevated frequency in Saguenay-Lac-St-Jean (SLSJ) and Charlevoix, two geographically isolated regions in the past of northeastern Quebec. The incidence at birth and the carrier rate in SLSJ were estimated at 1/1,932 liveborn infants and 1/22 inhabitants, respectively, for the period 1941-1985. The mean inbreeding coefficient was twice higher and the mean kinship coefficient 3 times higher among the ARSACS families than among control families. In the SLSJ region, the birth places of the ARSACS individuals and their parents did not show a clustered distribution. The genealogical reconstruction suggests that the high incidence of ARSACS in SLSJ and Charlevoix is likely to be the result of a founder effect. Because the disease is apparently unknown elsewhere in the world and a high proportion of French Canadians presently living in eastern Quebec have ancestors coming from Perche, a small region in France, it also suggests that a unique mutation accounts for most, if not all, of the ARSACS cases known in these regions.

Consanguinity↗