Biomedical subjects

M Jetté

Publications and source records attributed to M Jetté.

At least 19 recordsLinked to original sources

PubMed1998

A health profile of the Inuit of Nunavik: report of the Santé Québec Health Survey (1992).

This general survey of health and well-being aimed primarily to provide a comprehensive insight into the health and social situation in Nunavik, with a view to setting up prevention and intervention programs more properly adapted to the needs of the Inuit of Nunavik. The data gathered through the use of questionnaires were combined with the anthropometric and biological readings of some 1,567 Inuit of all ages to generate the survey findings. In essence, the report demonstrated that, as the current Inuit lifestyle, save for the consumption of traditional foods, was setting the stage for the development of several types of illness previously absent from Nunavik, behavioral changes were warranted. Although the Inuit reported few problems of a physical nature, mental health issues appeared challenging. The prevalence of psychological distress, suicidal thoughts, and parasuicides was of sufficient import to justify direct, concerted, and immediate action.

Adolescent↗

PubMed1997

A 13C mass isotopomer study of anaplerotic pyruvate carboxylation in perfused rat hearts.

Anaplerotic pyruvate carboxylation was examined in hearts perfused with physiological concentrations of glucose, [U-13C3]lactate, and [U-13C3]pyruvate. Also, a fatty acid, [1-13C]octanoate, or ketone bodies were added at concentrations providing acetyl-CoA at a rate resulting in either low or substantial pyruvate decarboxylation. Relative contributions of pyruvate and fatty acids to citrate synthesis were determined from the 13C labeling pattern of effluent citrate by gas chromatography-mass spectrometry (see companion article, Comte, B., Vincent, G., Bouchard, B., and Des Rosiers, C. (1997) J. Biol. Chem. 272, 26117-26124). Precision on flux measurements of anaplerotic pyruvate carboxylation depended on the mix of substrates supplied to the heart. Anaplerotic fluxes were precisely determined under conditions where acetyl-CoA was predominantly supplied by beta-oxidation, as it occurred with 0.2 or 1 mM octanoate. Then, anaplerotic pyruvate carboxylation provided 3-8% of the OAA moiety of citrate and was modulated by concentrations of lactate and pyruvate in the physiological range. Also, the contribution of pyruvate to citrate formation through carboxylation was equal to or greater than through decarboxylation. Furthermore, 13C labeling data on tissue citric acid cycle intermediates and pyruvate suggest that (i) anaplerosis occurs also at succinate and (ii) cataplerotic malate decarboxylation is low. Rather, the presence of citrate in the effluent perfusate of hearts perfused with physiological concentrations of glucose, lactate, and pyruvate and concentrations of octanoate leading to maximal oxidative rates suggests a cataplerotic citrate efflux from mitochondria to cytosol. Taken altogether, our data raise the possibility of a link between pyruvate carboxylation and mitochondrial citrate efflux. In view of the proposed feedback regulation of glycolysis by cytosolic citrate, such a link would support a role of anaplerosis and cataplerosis in metabolic signal transmission between mitochondria and cytosol in the normoxic heart.

Animals↗

PubMed1997

Radiation-inactivation analysis of the oligomeric structure of the renal sodium/D-glucose symporter.

The radiation-inactivation size (RIS) of the rat renal brush-border membrane sodium/D-glucose cotransporter was estimated from the loss of transport activity in irradiated membrane vesicles. The RIS depended on the electrochemical conditions present when measuring transport activity. A RIS of 294 +/- 40 kDa was obtained when transport was measured in the presence of a sodium electrochemical gradient. Under sodium equilibrium conditions, the RIS was 84 +/- 25 kDa in the presence of a glucose gradient, and 92 +/- 20 kDa in its absence. In the absence of a sodium gradient, but in the presence of an electrical potential gradient, the RIS increased to 225 +/- 49 kDa. The 294 kDa result supports earlier suggestions that the Na+ gradient-dependent glucose transport activity is mediated by a tetramer. Individual monomers appear, however, to carry out glucose transport under equilibrium exchange conditions or when a glucose gradient serves as the only driving force. The electrical potential gradient-driven glucose transport RIS appears to involve three functional subunits.

Animals↗

PubMed1997

The effect of ambient temperature and exercise intensity on post-exercise thermal homeostasis.

We have previously demonstrated a prolonged (65 min or longer) elevated plateau of esophageal temperature (T(es)) (0.5-0.6 degrees C above pre-exercise values) in humans following heavy dynamic exercise (70% maximal oxygen consumption, VO2max) at a thermoneutral temperature (T(a)) of 29 degrees C. The elevated T(es) value was equal to the threshold T(es) at which active skin vasodilation was initiated during exercise (Th(dil)). A subsequent observation. i.e., that successive exercise/recovery cycles (performed at progressively increasing pre-exercise T(es) levels) produced parallel increases of Th(dil) and the post-exercise T(es), further supports a physiological relationship between these two variables. However, since all of these tests have been conducted at the same T(a) (29 degrees C) and exercise intensity (70% VO2max) it is possible that the relationship is limited to a narrow range of T(a)/exercise intensity conditions. Therefore, five male subjects completed 18 min of treadmill exercise followed by 20 min of recovery in the following T(a)/exercise intensity conditions: (1) cool with light exercise, T(a) = 20 degrees C, 45% VO2max (CL); (2) temperature with heavy exercise, T(a) = 24 degrees C, 75% VO2max (TH); (3) warm with heavy exercise, T(a) = 29 degrees C, 75% VO2max (WH); and (4) hot with light exercise, T(a) = 40 degrees C, 45% VO2max (HL). An abrupt decrease in the forearm-to-finger temperature gradient (T(fa) - T(fi)) was used to identify the Th(dil) during exercise. Mean pre-exercise T(es) values were 36.80, 36.60, 36.72, and 37.20 degrees C for CL, TH, WH, and HL conditions respectively. T(es) increased during exercise, and end post-exercise fell to stable values of 37.13, 37.19, 37.29, and 37.55 degrees C for CL, TH, WH, and HL trials respectively. Each plateau value was significantly higher than pre-exercise values (P < 0.05). Correspondingly, Th(dil) values (i.e., 37.20, 37.23, 37.37, and 37.48 degrees C for CL, TH, WH, and HL) were comparable to the post-exercise T(es) values for each condition. The relationship between Th(dil) and post-exercise T(es) remained intact in all T(a)/exercise intensity conditions, providing further evidence that the relationship between these two variables is physiological and not coincidental.

Adult↗

PubMed1997

Health and gender differences between middle and senior managers in the Canadian Public Service.

Most studies of the relationship between socioeconomic status (SES) and health have concentrated on disparities between the richest and poorest men; few studies have examined such relationships for women due to difficulties in measuring SES for women. For the present study, data collected from Canadian Public Service middle and senior managers provided an opportunity to examine associations between SES and health within the upper end of the SES spectrum for both genders, since women managers can be assumed to have a relatively high SES. Demographic, health and lifestyle characteristics are compared for middle and senior managers for each gender separately to determine whether women experience the health benefits associated with higher SES that have been previously observed for men. The results support the hypothesis that achieving a higher SES through work is a more stressful process for women than for men and that women's upward mobility is restricted compared to that of men. Despite these findings, there is little evidence that women's health has been adversely affected. Compared to male managers, fewer female managers smoke or drink and fewer have high body mass index, high blood pressure or high cholesterol levels. Female managers are also more likely to report being in good health.

Administrative Personnel↗

PubMed1997

The effects of simulated akinetic and dyskinetic aneurysms on left ventricular systolic function: clinical implications.

OBJECTIVE: Scant attention has been directed towards quantifying the degree of mechanical disadvantage produced by akinetic and dyskinetic aneurysms. The purpose of this study was to evaluate the mechanical disadvantages of simulated akinetic and dyskinetic aneurysms on left ventricular function. METHODS: An elaborate experimental apparatus consisting of a computer-controlled water pressure chamber in which is suspended a model rubber ventricle was developed. The system has been shown to reproduce accurately the ventricular and aortic pressures found in vivo. In this study, a procedure was designed to simulate akinetic and dyskinetic aneurysms of various sizes on ventricular function. RESULTS: The results indicated that an akinetic aneurysm produces little or no mechanical disadvantage with respect to ventricular pressure since systolic paradox is minimal. However, a dyskinetic aneurysm, irrespective of size, will usually compromise ventricular function due to paradoxical systolic expansion in the bulging aneurysmic sac. In vivo, other factors, such as blood coagulation and rhythm disturbances, may influence these results. CONCLUSIONS: An akinetic aneurysm causes little or no mechanical disadvantage while the dyskinetic aneurysm, irrespective of size. will restrict ventricular function. The experimental simulation system, notwithstanding its limitations, thus provides a unique procedure to quantify akinetic and dyskinetic aneurysms.

Heart Aneurysm↗

PubMed1996

The renal sodium/phosphate symporters: evidence for different functional oligomeric states.

The oligomeric size of the rat renal sodium/phosphate symporters was estimated in brush-border membrane vesicles submitted to radiation inactivation. Altering the electrochemical conditions under which phosphate transport was measured resulted in different molecular size determinations. The radiation inactivation size (RIS) obtained from the radiation-induced loss of transport activity measured in the presence of a sodium gradient was 200 kDa. Under sodium equilibrium conditions, in the presence of a phosphate gradient as the only driving force, transport fell to 13% of the activity measured in the presence of a sodium gradient, and the RIS was 62 kDa. Addition of an outwardly-directed proton gradient increased the transport activity to 29% of that measured in the presence of a sodium gradient. The RIS measured under these conditions was 124 kDa. Under all conditions tested, phosphate uptake by irradiated vesicles was significantly reduced but remained linear during the first 5 s of incubation. The radiation-induced loss of transport activity was thus attributable to a direct inactivation of the transporter rather than to a decrease in the physical integrity of the vesicles. These results are consistent with a tetrameric structure composed of subunits of about 62 kDa and suggest that phosphate transport involves both monomers and tetramers.

Animals↗

PubMed1996

The renal brush border membrane sodium/sulfate cotransporter functions in situ as a homotetramer.

The functional molecular size of the renal Na+/SO4(2-) cotransporter was analysed with the radiation inactivation and fragmentation method. Purified brush border membrane vesicles preserved in a cryoprotective medium were exposed to gamma-radiations. Initial rates of SO4(2-) influx into these vesicles were estimated with membranes irradiated with 0, 4 and 8 Mrad. In each case, SO4(2-) uptake by irradiated membranes was significantly reduced but remained linear during the first 5 sec of incubation. To avoid artifacts arising from a decrease in the driving force caused by modifications in membrane permeability, this incubation period was chosen to measure the effect of irradiation on the SO4(2-) transport activity. Increasing irradiation doses resulted in a monoexponential decrease in transport activity allowing the molecular size to be estimated at 238 +/- 6 kDa (SD, n = 3). Recently, a cDNA for the Na+/SO4(2-) cotransporter was cloned and expressed in Xenopus laevis oocytes (Markovich D. et al. (1993) Proc. Natl Acad. Sci. U.S.A. 90, 8073-8077). The deduced amino acid sequence of this cotransporter predicts a molecular weight of 66 kDa. We suggest that the in situ activity of the renal brush border membrane Na+/SO4(2-) cotransporter requires the presence of four intact and identical subunits arranged as a homotetramer.

Animals↗

PubMed1995

Reproducibility of body temperature response to standardized test conditions when assessing clothing.

The traditional use of core temperature to assess the thermal effects of clothing has recently been questioned. The purpose of this study was to assess the reproducibility of body temperature in five subjects (mean age, 22.6 +/- 1.5 years) wearing either athletic clothing or a chemical protective overgarment while exercising at 20 degrees C and at 40 degrees C. The exercise was preceded by a 1 h adaptation period in a controlled environmental chamber. Results indicated that mean group change in rectal temperature (delta Tr) appeared to be reproducible for both garment ensembles at 20 degrees C but not at 40 degrees C. For mean change in oesophageal temperature (delta T(oes)) at 20 degrees C, reproducibility was obtained for the overgarment but not for the athletic garment; at 40 degrees C, mean delta T(oes) appeared to be reproducible with both garments. However, when individual responses were examined, there was little reproducibility for either delta Tr or delta T(oes). In addition, these measurements failed to show differences in the types of clothing worn. It was concluded that the use of core temperature to assess heat stress imposed by wearing clothing during exercise may lead to erroneous conclusions.

Adult↗

PubMed1995

Metabolism of (R,S)-1,3-butanediol acetoacetate esters, potential parenteral and enteral nutrients in conscious pigs.

The (R,S)-1,3-butanediol-acetoacetate monoesters and diester are nonionized sodium-free precursors of ketone bodies (beta-hydroxybutyrate and acetoacetate). They represent a convenient form of ketone body administration for parenteral and enteral nutrition. We have studied the metabolism of the esters in the conscious pig, an animal in which ketogenesis is congenitally impaired. Some pigs were infused for 3 h, intravenously or intragastrically, with the esters or with (R,S)-1,3-butanediol at 30% of the hourly caloric requirement. Other pigs were given intragastric boluses of esters or of (R,S)-1,3-butanediol at 15% of the daily caloric requirement. Our data show that continuous infusion of the esters at 30% of the caloric requirement leads to low concentrations of (R,S)-1,3-butanediol (0.1 mM) and total ketone bodies (0.5 mM). In pigs given intragastric boluses of esters at 15% of the daily caloric requirement, concentrations of (R,S)-1,3-butanediol and total ketone bodies peaked briefly at 2-3 and 5 mM, respectively. No deleterious side effects were observed in any group, including no hypoglycemia and no acidosis. Thus the (R,S)-1,3-butanediol acetoacetate esters appears to be well utilized as a nutrient by the pig despite its impaired ketogenesis.

3-Hydroxybutyric Acid↗

PubMed1994

Blood pressure responses to a progressive step test in normotensive males and females.

This study documents the blood pressure responses to a progressive step test adapted from the Canadian Aerobic Fitness Test (CAFT). Subjects were administered the first five stages of the CAFT in a progressive and discontinuous manner. Mean heart rate, SBP, and delta SBP increased linearly with exercise intensity, while mean diastolic blood pressure remained stable. The variables that contributed most to delta SBP (Stage 3) in males were age and degree of participation in physical activity, and in females the variables were body weight and degree of participation. Criteria for the detection of an exaggerated (mean delta SBP + 1 SD) and highly exaggerated (mean delta SBP + 2 SD) SBP response were defined. Resting normotensive individuals who demonstrate an excessive exercise blood pressure response seem to do so at the lowest levels of stepping intensities. This step test protocol appears to be a useful and practical procedure for assessing the exercise blood pressure response in higher risk individuals.

Adult↗

PubMed1993

Acyloin production from aldehydes in the perfused rat heart: the potential role of pyruvate dehydrogenase.

Aldehydes represent an important class of cytotoxic products derived from free radical-induced lipid peroxidation which may contribute to reperfusion injury following myocardial infarct. Metabolism of aldehydes in the heart has not been well characterized aside from conjugation of unsaturated aldehydes with glutathione. However, aliphatic aldehydes like hexanal do not form stable glutathione conjugates. We have recently demonstrated in vitro that pig heart pyruvate dehydrogenase catalyses a reaction between pyruvate and saturated aldehydes to produce acyloins (3-hydroxyalkan-2-ones). In the present study, rat hearts were perfused with various aldehydes and pyruvate. Acyloins were generated from saturated aldehydes (butanal, hexanal or nonanal), but not from 2-hexanal (an unsaturated aldehyde) or malondialdehyde. Hearts perfused with 2 mM pyruvate and 10-100 microM hexanal rapidly took up hexanal in a dose-related manner (140-850 nmol/min), and released 3-hydroxyoctan-2-one (0.7-30 nmol/min), 2,3-octanediol (0-12 nmol/min) and hexanol (10-200 nmol/min). Small quantities of hexanoic acid (about 10 nmol/min) were also released. The rate of release of acyloin metabolites rose with increased concentration of hexanal, whereas hexanol release attained a plateau when hexanal infusion concentrations rose above 50 microM. Up to 50% of hexanal uptake could be accounted for by metabolite release. Less than 0.5% of hexanal uptake was found to be bound to acid-precipitable macromolecules. When hearts perfused with 50 microM hexanal and 2 mM pyruvate were subjected to a 15 min ischaemic period, the rates of release of 2,3-octanediol, 3-hydroxyoctan-2-one, hexanol and hexanoate during the reperfusion period were not significantly different from those in the pre-ischaemic period. Our results indicate that saturated aldehydes can be metabolically converted by the heart into stable diffusible compounds.

Aldehydes↗

PubMed1993

Electrocardiographic responses to jogging in middle-aged and older men and women.

Recent jogging-related sudden deaths rekindled the concern among health professionals as to the hazards of strenuous exercise. The purpose of this study was to evaluate the extent of rhythm disturbances and myocardial ischemia in older men and women during a typical strenuous jogging session. Twenty-two members of a local jogging club (11 men and 11 women) between the ages of 50 and 66 years participated in the study. The CardioData PR3/ST monitor was employed to record heart rate, rhythm disturbances, J point and ST slope during the course of the run. The men ran a 10 km run and the women a 6 km run at a competitive pace. The mean maximal heart rate during the run was 170 +/- 15 beats/min for the males and 176 +/- 14 beats/min for the females. The mean J point during the run was -3.39 +/- 1.21 mV for the males and -2.97 +/- 0.96 mV for the females. Females showed a significantly lower mean ST slope (3.95 +/- 0.91 mV) during the run than the males (5.56 +/- 1.37 mV, p < 0.05). A number of episodes of premature ventricular beats, both uni- and multifocal, were observed. Exercise testing of sufficient intensity is recommended to detect those persons susceptible to developing serious arrhythmias during strenuous exercise.

Aged↗

PubMed1993

Gas chromatographic-mass spectrometric assay of tissue malondialdehyde, 4-hydroxynonenal, and other aldehydes after their reduction to stable alcohols.

Measurement of specific aldehydes such as malondialdehyde, hexanal, or 4-hydroxynonenal provides a method to evaluate the extent of lipid peroxidation. However, assay of aldehydes is complicated by their high reactivity toward other molecules and their chemical instability. In the proposed method, aldehydes are reduced to stable alcohols. Except for malondialdehyde, this is readily accomplished under neutral conditions at room temperature or at 4 degrees C with either sodium borodeuteride (NaB2H4) or sodium borohydride (NaBH4). Complete reduction of malondialdehyde requires a more powerful reducing agent, borane trimethylamine. After ether extraction and evaporation of the organic phase, the alcohols are converted to t-butyldimethylsilyl ethers and analyzed by selected ion monitoring gas chromatography-mass spectrometry in the positive chemical ionization mode for malondialdehyde and 4-hydroxynonenal and electron impact mode for all other aldehydes. Quantitation is achieved using internal standards of 1,3-[2H8]propanediol for MDA, of 4-[2-2H]hydroxynonenal for 4-hydroxynonenal, and of the corresponding saturated per-deuterated alcohols for all saturated aldehydes, for example and [2H13]hexanol for hexanal. Saturated per-deuterated alcohols also serve as external standards for their unsaturated aldehydes with same chain length. The detection limit for individual aldehydes is 0.5 nmol in a given sample. In addition to being highly sensitive and selective, the present method allows one to verify the identity of each aldehyde by observing a mass shift when aldehydes are reduced with either NaB2H4 or NaBH4. The usefulness of our method is demonstrated by measuring aldehyde accumulation in autoxidized arachidonic acid solutions and in heart homogenates before and after induction of peroxidation.

Alcohols↗

PubMed1993

Association between an excessive body mass index and coronary heart disease risk factors in military personnel.

The purpose of this study was to document the extent of coronary heart disease (CHD) risk factors in military personnel (412 men, 50 women) classified as seriously overweight (body mass index [BMI] 27.0-29.9 kg/m2) or obese (BMI > or = 30 kg/m2) and to evaluate the utility of the BMI to discriminate among individuals with an adverse CHD risk profile. Mean body weight and BMI greatly exceeded Canadian norms, whereas mean heights were average. There were low but significant correlations between BMI and resting and submaximal exercise (stage A of the Canadian Aerobic Fitness Test) heart rates and blood pressures, while the correlation with predicted VO2max was negative. Except for blood glucose level (GLU) in men, there were no significant correlations between BMI and various biochemical indices. Compared to "overweight" men, the percentage of "obese" men with abnormal values for risk factors were higher, particularly for an adverse exercise blood pressure response and low predicted VO2max. In summary, the correlations between BMI and the various CHD risk factors, except for GLU and the exercise parameters, were minimal or moderate at best. It was concluded that in overweight and obese individuals, BMI does not appear to be a particularly sensitive indicator of body fat and risk factors.

Adult↗

PubMed1992

Metabolism of R- and S-1,3-butanediol in perfused livers from meal-fed and starved rats.

The metabolism of millimolar concentrations of R- or S-1,3-butanediol has been studied in perfused livers from fed and starved rats. Protocols were designed to measure in the same experiment (i) uptake of the diol, (ii) the contribution of the diol to ketogenesis, (iii) the contribution of the diol to total fatty acid plus sterol synthesis, and (iv) conversion of S-1,3-butanediol into S-3-hydroxybutyrate. Our data show that R- and S-1,3-butanediol are taken up by the liver at the same rate. Most of the metabolism of R-1,3-butanediol is accounted for by conversion to the physiological ketone bodies R-3-hydroxybutyrate and acetoacetate. Only 29-38% of S-1,3-butanediol uptake is accounted for by conversion into physiological ketone bodies. The balance of S-1,3-butanediol metabolism is conversion to S-3-hydroxybutyrate, lipids and CO2.

Animals↗

PubMed1992

[Short stature as a risk indicator for coronary patients].

BACKGROUND: Short stature as an indicator of coronary disease in German men is described. PATIENTS AND METHODOLOGY: A total of 4,524 patients investigated by coronary angiography (history of myocardial infarction and at least one vessel greater than or equal to 75% stenotic or occluded on angiography and, in addition corresponding levocardiographic changes) and 722 age-matched test subjects with unremarkable coronary angiographic findings were admitted to the study. RESULTS: The patients with coronary heart disease were, on average, 1.9 cm shorter than those with unremarkable blood vessels. This difference in height was found in particular in the age group between 40 and 60 years old. The reason for this is not known.

Adult↗

PubMed1992

Relation between cardiorespiratory fitness and selected risk factors for coronary heart disease in a population of Canadian men and women.

OBJECTIVE: To determine the relation between cardiorespiratory fitness, as determined with the Canadian Aerobic Fitness Test (CAFT), and selected risk factors for coronary heart disease (CHD) in a Canadian population. DESIGN: Cross-sectional study. On the basis of age-specific and sex-specific national percentile scores, subjects were classified as being in the low-fitness, moderate-fitness or high-fitness category according to maximum oxygen consumption (VO2 max) predicted from performance on the CAFT. PARTICIPANTS: A total of 4082 male and 1205 female Canadian federal public servants aged 30 to 59 years who participated in a voluntary fitness testing program between 1984 and 1991. OUTCOME MEASURES: Body composition (body mass index, triceps skinfold thickness, sum of four skinfold measurements, predicted percentage of body fat and waist-hip ratio), blood lipid levels (total cholesterol, triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol and ratio of total cholesterol to HDL-C) and hemodynamic measurements (heart rate and blood pressure at rest and during exercise and predicted VO2 max). MAIN RESULTS: For both men and women the mean anthropometric measurements, blood lipid levels and blood pressure measurements at rest and after exercise were significantly associated with fitness category (p less than 0.05). CONCLUSIONS: In both men and women a higher level of aerobic fitness, as defined by VO2 max predicted from performance on the CAFT, is associated with a more favourable CHD risk profile. The results support the use of VO2 max predicted from performance on the CAFT as a valid procedure for classifying people according to fitness level.

Adult↗