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Biomedical subjects

M Ledoux

Publications and source records attributed to M Ledoux.

At least 19 recordsLinked to original sources
PubMed2004

Factors associated with overweight and obesity in Quebec adults.

OBJECTIVE: To measure the independent correlates of excess body weight and obesity in Quebec in 1993 and 1997. DESIGN: A population-based, cross-sectional survey in three settings in the province of Quebec. SUBJECTS: A total of 10014 individuals aged 18-64 y. MEASUREMENTS: Excess body weight was defined as a body mass index (BMI) (self-reported weight and height) greater than or equal to 25 kg/m(2) and obesity as BMI greater than or equal to 30 kg/m(2). Data were collected by a questionnaire completed at home by the participants. Diet was assessed by a food frequency questionnaire. RESULTS: The correlates varied according to gender. While university achievement, smoking habit and physical activity level reduced the risk of excess body weight in both genders, increased dietary fat intake was positively associated with overweight and obesity in men only. In women, greater family income lowered the risk of having a BMI over 25. Increasing age, speaking a language other than French and living in a rural environment elevated the risk. CONCLUSION: Future interventions for the control of obesity should be gender-specific. Target groups should include individuals with low education, those living in rural environments and non-caucasian women. Dietary interventions should target men in particular.

Adolescent↗
PubMed2002

Occurrence of trans-C18:1 fatty acid isomers in goat milk: effect of two dietary regimens.

Trans-octadecenoic acid composition of goat milk fat was studied by using silver-ion thin layer chromatography combined with gas-liquid chromatography. This analytical procedure also was used to investigate the effect of diet on trans-C18:1 fatty acid content in goat milk. Thirty-two goats were used in a 2 x 2 factorial arrangement and treatments. Two groups of goats received alfalfa hay at either a high or a low level of forage and two other groups received Rumiluz (dehydrated alfalfa from France Luzerne, Châlon en Champagne, France) at either a high or a low level of forage. Trans-C18:1 isomer proportions (relative to total fatty acids) were, respectively, 2.02% for the Rumiluz low-level group and 1.75% for the Rumiluz high-level group versus 1.71% for the alfalfa low-level group and 1.21% for the alfalfa high-level group. Goats fed on Rumiluz thus produced relatively higher levels of trans-C18:1 fatty acids than animals fed alfalfa hay. The results also showed that production of trans-C18:1 fatty acids increased when the level of forage in the diet decreased. Moreover, goat milk trans-C18:1 composition appeared similar to the cow milk profile. Vaccenic acid, trans-11-C18:1, was the major component and represented about 36.2% of total trans-C18:1 isomers.

Animal Feed↗
PubMed2001

Biomechanical properties of braided polyester tapes intended for use as intra-articular cranial cruciate ligament prostheses in dogs.

OBJECTIVE: To determine the in vitro structural and material properties of braided, multifilament, nonabsorbable polyester tapes, used for intra-articular stabilization of cranial cruciate ligament- (CCL-) deficient stifle joints in dogs, and compare those with properties of multifilament polyamide tapes. SAMPLE POPULATION: 30 polyester tapes (width, 4 mm), 10 polyester tapes (width, 7 mm), and 30 polyamide tapes (width, 4 mm) were tested to failure. Cyclic loading experiments were also performed, using 3 polyester tapes of each width. PROCEDURE: Tapes were mounted in a tensile tester as single loops, simulating intra-operative conditions, and elongated to failure at 1,000 mm/min. Additionally, the behavior of polyester tapes was tested at different elongation rates. In a second series of experiments, biomechanical variables of the polyester tapes were measured after 25 sets of 2,000 cycles between physiologic force limits. RESULTS: Mean (+/- SD) ultimate loads of the 4-mm wide polyamide tapes, 4-mm wide polyester tapes, and 7-mm wide polyester tapes were 266.48 +/- 13.19 301.78 +/- 16.92, and 726.40 +/- 37.74 N, respectively. Corresponding stiffnesses were 15.57 +/- 0.49, 21.63 +/- 2.19, and 34.85 +/- 2.66 N/mm, respectively. Failure properties of polyester tapes were affected by previous cyclic loading. CONCLUSIONS AND CLINICAL RELEVANCE: Polyester tapes of 4- or 7-mm widths should be able to resist forces resulting from weight bearing in dogs, suggesting that these tapes will be effective for stabilization of the stifle joint in dogs with a ruptured CCL.

Animals↗
PubMed2000

Increased thermogenic response to food and fat oxidation in female athletes: relationship with VO(2 max).

The thermogenic response to food (TRF) and substrate oxidation were studied in 12 endurance-trained and 13 untrained female subjects. Energy expenditure and substrate oxidation were calculated by indirect calorimetry before and for 6 h after an oral test meal and after the same meal given intragastrically on a separate occasion. The TRF was calculated after the oral meal, the obligatory component after the intragastric meal (OTRF), and the facultative component from the difference between the two. VO(2 max) was measured on a treadmill and body composition by underwater weighing. The TRF and OTRF were significantly higher in trained than in untrained subjects: 223 +/- 63 vs. 185 +/- 50 kJ/6 h (P < 0.03) and 174 +/- 38 vs. 131 +/- 37 kJ/6 h (P < 0.01) for the TRF and OTRF in trained vs. untrained subjects, respectively. Multiple regression analysis showed that maximum O(2) consumption (VO(2 max)), but not percentage of body fat, was significantly related to OTRF (r =0.68, P < 0.01). Trained subjects had higher fatty acid oxidation than untrained subjects before (0.6 vs. 0.4 mg. kg(-1). min(-1), P < 0.05) and after the oral meal (13 +/- 6 vs. 8 +/- 4 g/6 h P < 0.05). These results demonstrate that 1) TRF is higher in trained than in untrained women; 2) this is due to a higher cost of nutrient digestion, absorption and storage; 3) the difference is related to higher VO(2 max); and 4) fatty acid oxidation is greater in trained women in both the postabsorptive and postprandial states. These observations suggest that endurance training induces metabolic changes that favor leanness.

Adipose Tissue↗
PubMed2000

Iron-ascorbate alters the efficiency of Caco-2 cells to assemble and secrete lipoproteins.

Although oxidative stress has been implicated in development of gut pathologies, its role in intestinal fat transport has not been investigated. We assessed the effect of Fe(2+)-ascorbate-mediated lipid peroxidation on lipid synthesis, apolipoprotein biogenesis, and lipoprotein assembly and secretion. Incubation of postconfluent Caco-2 cells with iron(II)-ascorbate (0.2 mM/2 mM) in the apical compartment significantly promoted malondialdehyde formation without affecting sucrase activity, transepithelial resistance, DNA and protein content, and cell viability. However, addition of the oxygen radical-generating system reduced 1) [(14)C]oleic acid incorporation into cellular triglycerides (15%, P < 0.0002) and phospholipids (16%, P < 0.0005); 2) de novo synthesis of cellular apolipoprotein A-I (apo A-I) (18%, P < 0.05), apo A-IV (38%, P < 0.05), and apo B-48 (45%, P < 0.003) after [(35)S]methionine addition; and 3) production of chylomicrons (50%), VLDL (40%), LDL (37%), and HDL (30%) (all P < 0.0001). In contrast, increased total cellular cholesterol formation (96%, P < 0.0001), assayed by [(14)C]acetate incorporation, was noted, attributable to marked elevation (70%, P < 0.04) in activity of DL-3-hydroxy-3-methyl-glutaryl-CoA reductase, the rate-limiting enzyme in cholesterol synthesis. The ratio of Acyl-CoA to cholesterol acyltransferase, the esterifying cholesterol enzyme, remained unchanged. Fe(2+)-ascorbate-mediated lipid peroxidation modifies intracellular fat absorption and may decrease enterocyte efficiency in assembling and transporting lipids during gut inflammation.

Antineoplastic Agents↗
PubMed1999

Introducing management principles into the supply and distribution of medicines in Tunisia.

A number of strategies have been proposed by various organizations and governments for rationalizing the use of drugs in developing countries. Such strategies include the use of essential drug lists, generic prescribing, and training in rational prescribing. None of these require doctors to become actively involved in the management of the drug supply to their health centres. In 1997, in the Kasserine region of Tunisia, the regional health authorities piloted a radically different strategy. This involved the theoretical allocation of a proportion of the regional drug budget to each district and subsequently to each health centre according to estimated demand. Medical staff were given responsibility for the management of these budgets, allowing them to control the nature and quantities of drugs supplied to the health centres in which they worked. This paper outlines the process by which this strategy was successfully implemented in the Foussana district of Kasserine region, and explores the problems encountered. It describes now the theoretical budgets were allocated to each district and how the costs of individual drugs and the consumption of drugs in the previous year were calculated. It then continues by giving an account of the training of the staff of the health centres, the preparation of a drug order form and the method of allocation of the theoretical budgets to each of the health centres. The results give an account of how the prescribing habits of doctors were changed as a result of the strategy, in order to take into account the costs of the drugs that they prescribed. They show how the health centres were able to manage their budgets, spending overall 99.8% of the budget allocated to the district. They outline some of the changes in the prescribing habits that took place, demonstrating a greater use of appropriate and essential drugs. The paper concludes that doctors and paramedical staff can successfully manage a theoretical drug budget, and that their involvement in this process leads to more rational prescribing within existing resource constraints. This has a consequence of benefiting patients, satisfying doctors and pleasing administrators.

Budgets↗
PubMed1997

A comparative analysis of weight to height and waist to hip circumference indices as indicators of the presence of cardiovascular disease risk factors. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To determine the mathematic formula for weight, height and waist and hip circumference that is most closely correlated to cardiovascular disease risk factors. DESIGN: Population-based, cross-sectional surveys. SETTING: Five Canadian provinces, between 1990 and 1992. PARTICIPANTS: A probability sample of 16,007 men and women aged 18 to 74 years was selected using health insurance registration files in each province. Anthropometry was performed on 10,054 (63%) of these adults. OUTCOME MEASURES: The power of height in the body mass index (BMI, kg/m2) and of hip circumference in the ratio of waist to hip circumference (WC/HC) was varied from 0 to 3. Simple linear regression analysis for each age-sex group was used to examine the relation of each index to systolic and diastolic blood pressure (SBP and DBP), levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL), triglycerides (TRIG) and the ratio of TC to HDL. Values for the coefficient of determination (r2) were used to compare the fits of the models. RESULTS: The r2 values were generally low (< 0.27), but were greatest in the younger age groups (18-24 and 35-54 years) and in women. Waist circumference alone (WC/HC0) showed the best fit with SBP and DBP, whereas WC/HC0.5 was most closely related to HDL, TC/HDL and TRIG. None of the indices was closely associated with TC or LDL. Whatever the power of height used, the weight-height ratios showed weaker associations with the risk factors than the waist-hip ratios. CONCLUSIONS: WC and BMI correlate most closely with blood pressure and plasma lipid and may be the best simple anthropometric indices to include in the routine clinical examination of adults.

Adult↗
PubMed1997

Correlation between cardiovascular disease risk factors and simple anthropometric measures. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To assess simple anthropometric measures as indicators of the concurrent presence of high blood pressure, dyslipidemia and diabetes mellitus in adults. DESIGN: Population-based, cross-sectional surveys. SETTING: Five Canadian provinces between 1990 and 1992. PARTICIPANTS: A probability sample of 16,007 men and women aged 18 to 74 years was selected using health insurance registration files in each province. This study is based on the 9826 adults (61%) for whom anthropometric measurements were obtained. OUTCOME MEASURES: Step-wise multiple logistic regression analysis was used to model the association between demographic, anthropometric and risk variables and the presence of high systolic and diastolic (DBP) blood pressure, elevated levels of total (TC), high-density lipoprotein (HDL) and low-density lipoprotein cholesterol, TC/HDL ratio, triglyceride levels (TRIG) and self-reported diabetes mellitus. RESULTS: Age group and sex are strongly associated with all three conditions. Sedentary lifestyle is significantly associated with high DBP, depressed HDL and elevated TC/HDL and TRIG. Anthropometric measures are moderately associated with all conditions. The measures of body fat (body mass index) as well as abdominal fat distribution (waist circumference and ratio of waist to hip circumference) play an approximately equal role. CONCLUSION: Patients' age, sex, level of physical activity, body fat and abdominal fat distribution can be used as indicators of the probability of high blood pressure, dyslipidemia and diabetes mellitus.

Adult↗
PubMed1996

Acute treatment with the N-methyl-D-aspartate receptor antagonist MK-801: effect of concurrent administration of haloperidol or scopolamine on preproenkephalin mRNA levels of the striatum and nucleus accumbens of the rat brain.

We injected rats three times at 3 h intervals (from 0900 h to 1500 h) with the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 at 0.1 or 0.5 mg/kg of body weight. Three hours after the last injection, animals were sacrificed and the brains were processed for in situ hybridization histochemistry. Preproenkephalin (PPE) mRNA levels were significantly decreased throughout the caudate-putamen (CPu) and nucleus accumbens (NAc) at the lower dose. The higher dose produced significant decreases only in anterior CPu (aCPu) and NAc. Concurrent administration of the muscarinic cholinergic receptor antagonist scopolamine at 2 or 5 mg/kg neither potentiated nor prevented the effect of MK-801 on PPE mRNA levels in the neostriatum. In contrast, co-administration of haloperidol (dopamine receptor antagonist) with MK-801 blocked the effect of the latter in the NAc, and elevated PPE mRNA levels throughout the CPu. The data demonstrate that the acute effects of glutamate receptor activity on striatal and accumbal PPE mRNA expression via the NMDA receptor can be modulated by the dopaminergic system in the brain of the rat.

Animals↗
PubMed1995

Elevation of striatal and accumbal preproenkephalin, preprotachykinin and preprodynorphin mRNA abundance subsequent to N-methyl-D-aspartate receptor blockade with MK-801.

The effect of N-methyl-D-aspartate (NMDA) receptor blockade on the expression of preproenkephalin (PPE), preprotachykinin (PPT) and preprodynorphin (PPD) mRNAs in the caudate-putamen and nucleus accumbens was assessed with the non-competitive NMDA receptor antagonist MK-801. Administration of MK-801 once daily for 7 consecutive days increased the abundance of all three neuropeptide mRNAs in the caudate-putamen (CPU) and nucleus accumbens (NAc). (1) PPE mRNA abundance was increased in the anterior CPU (26%) as well as dorsal and ventral CPU (46% and 39%, respectively) but was unaffected in the NAc. (2) PPT mRNA was increased in the NAc (33%), anterior CPU (27%), dorsal CPU (43%) and ventral CPU (67%). In the ventral CPU, PPT mRNA abundance doubled when the dose of MK-801 increased two-fold (from 67% to 119% above control). (3) PPD mRNA was elevated in dorsal and ventral regions of the CPU (49% and 24%, respectively) and in anterior CPU (50%). In the NAc PPD mRNA was increased only at the higher dose (0.1 mg/kg) of MK-801. Cellular analysis of the distribution of grains per cell shows that increases are due to increased accumulation of mRNA by previously expressing cells of the CPU and NAc. These observations demonstrate that NMDA receptor activity plays a significant role in the regulation of neuropeptide expression in the caudate-putamen and accumbens of the rat brain.

Animals↗
PubMed1995

Eosinophilic pustular folliculitis in three atopic children with hypersensitivity to Dermatophagoides pteronyssinus.

Three children will be described who present recurrent episodes of pruritic papulopustular follicular lesions on the face, the extremities and the trunk. The episodes lasted for 1-3 months with intermittent remission. Each flare was accompanied by hypereosinophilia and an increased total IgE titer. RAST and prick tests were positive for Dermatophagoides pteronyssinus (DPT). Laboratory tests disclosed no infectious or parasitic etiology. Histological examination showed eosinophilic pustular folliculitis (EPF) in each of the 3 cases. The lesions responded well to topical corticosteroids. The aim of this article is to underline the importance of hypersensitivity reactions (in these particular cases to DPT) in the pathogenesis of EPF.

Adolescent↗
PubMed1995

Lymphomatoid papulosis: a clinical case.

We report a case of lymphomatoid papulosis in a 36-year-old man who presented recurrent necrotic skin nodules that regressed spontaneously leaving scars. The condition had persisted since 1988. These nodules were always solitary and located on the extremities. Histological examination revealed a perivascular and interstitial, superficial and deep infiltrate with numerous atypical lymphocytes (> 40%) characterized by cerebriform mononuclear cells and large atypical cells stained by MT1, UCHL1 and Ber-H2 (anti-CD30). No associated disease was found. The patient has been free of lesions for more than a year without treatment. A nosological and physiopathological hypothesis of lymphomatoid papulosis is discussed.

Adult↗
PubMed1994

Kinetics of Alexandrium minutum Halim toxin accumulation in mussels and clams.

Mussels (Mytilus edulis) and clams (Ruditapes philippinarum) were contaminated experimentally using cultures of Alexandrium minutum, a toxic dinoflagellate isolated from French coastal waters. Experiments were carried out in continually flushed and open-circuit systems using Alexandrium densities of 100 to 700 cells/ml delivered to tanks containing the shellfish. All experiments indicated an inversion of the relative proportions of gonyautoxins (GTX2 and GTX3) in shellfish meat during decontamination, whereas saxitoxin (STX) only accumulated during mussel depuration. However, in mussels a density as low as 100 cells/ml led within 10 days to bioaccumulation of paralytic shellfish poisoning (PSP) toxins above the public health threshold. Similar results were observed in clams subjected to fivefold higher cell densities, indicating a less effective assimilation of the dinoflagellate than by mussel. Decontamination experiments on PSP toxin-contaminated mussels (360 micrograms STX eq./100 g or lower uptake) fed two nontoxic diets (1,000 and 10,000 cells/ml of Tetraselmis suesica) showed an appreciable reduction in the time needed to decrease toxin concentration below the accepted threshold for human consumption. We suggest that a simple relation can be established between initial toxicity, the concentration of nontoxic alga available, and the time required for depuration once decontamination kinetics becomes linear and corresponds to the inverse of contamination kinetics.

Animals↗
PubMed1994

Moderate long-term physical activity improves the age-related decline in bile formation and bile salt secretion in rats.

This study examined the effect of moderate long-term exercise, begun soon after weaning, on the age-related decline in bile formation and the secretory rate maximum (SRm) of taurocholate (TC), the major bile salt (BS) in rats. Eight-month-old sedentary (S) female Sprague-Dawley rats showed a significant decrease in basal and TC-stimulated bile formation when compared with 2.5-month-old S controls. As in younger rats, decreased biliary phospholipid (PL) output was associated with the TC SRm, but this change appeared much more rapidly in S animals, which also exhibited significant increased plasma lipids and higher TC concentrations in plasma and liver at the end of the TC infusion. Exercise significantly improved bile flow (BF), including the bile salt-dependent and -independent fractions under basal and TC-stimulated conditions in 8 month-old rats. Although all the biliary parameters evaluated were improved, maximal BF and PL secretion values were affected the most and were virtually not different from those obtained in younger S animals. Exercise also significantly lowered the age-related elevation of plasma PL. Thus, moderate long-term exercise exerts a beneficial effect on hepatobiliary function and the BS SRm, an effect that may be attributed in part to increased availability of a biliary PL pool previously implicated in regulation of the BS SRm.

Age Factors↗
PubMed1994

[Plexiform fibrohistiocytic tumor].

Plexiform fibrohistiocytic tumour has been recently described by Enzinger and Zhang. This is a rare tumour with low grade malignancy which requires large excision. We report two cases, one occurring in a 58-year-old man, presenting a voluminous painless mass of 5 cm on his hand, the other occurring in a 9-year-old boy consulting for a nodule on the chest. On histological examination this dermal hypodermal tumour is characterized by a proliferation of histiocytic-like cells grouped in nodules, where they are associated with multinucleated osteoclastic-like cells and a proliferation of fibroblastic-like cells grouped in fascicles, anastomosing in a plexiform pattern. Immunohistochemistry and ultrastructural aspects are described. Differential diagnosis and histogenesis are discussed.

Child↗
PubMed1993

Upregulation of forebrain proenkephalin mRNA subsequent to NMDA receptor blockade.

Blockade of NMDA (N-methyl-D-aspartate) receptors for 5 h with MK 801 resulted in elevated levels of proenkephalin mRNA (up to 40% above vehicle-injected controls) in medial and anterior aspects of the caudate-putamen (mCPU and aCPU) and the nucleus accumbens (NAc). Increases were dose-dependent, with maximal effect at 0.1 mg/kg (body weight). These results suggest that NMDA receptor activity exerts tonic inhibition on proenkephalin mRNA expression in the striatum and accumbens of the rat brain.

Animals↗