Marie-France Langlois

Reproducibility of the 6-minute walk test in obese adults.

The six-minute walk test (6MWT) is an inexpensive, quick and safe tool to evaluate the functional capacity of patients with heart failure and chronic obstructive pulmonary disease. The aim of this study was to determine the reproducibility of the 6MWT in overweight and obese individuals. We thus undertook a prospective repeated-measure validity study taking place in our academic weight management outpatient clinic. The 6MWT was conducted twice the same day in 21 overweight or obese adult subjects (15 females and 6 males). Repeatability of walking distance was the primary outcome. Anthropometric measures, blood pressure and heart rate were also recorded. Participants mean BMI was 37.2+/-9.8 kg/m(2) (range: 27.0-62.3 kg/m(2)). Walking distance in the morning (mean=452+/-90 m) and in the afternoon (mean=458+/-97 m) were highly correlated (r=0.948; 95% Confidence Interval 0.877-0.978; p<0.001). Walking distance was negatively correlated with BMI (r=-0.47, p=0.03), waist circumference (r=-0.43, p=0.05) and pre-test heart rate (r=-0.54, p=0.01). Our findings indicate that the 6MWT is highly reproducible in obese subjects and could thus be used as a fitness indicator in clinical studies and clinical care in this population.

Prevention of weight gain in young adults through a seminar-based intervention program

Objective:Prevention would be the ideal public health strategy to face the current obesity epidemic. Adoption of healthy lifestyles during the first years of college or university could prevent the onset of weight gain associated with this period of acquired independence and eventually decrease the incidence of obesity.Design:Randomized-controlled trial over a period of 2 years. The subjects received an educational/behavioral intervention (small group seminars) designed to help maintain a healthy lifestyle or no specific intervention (control group).Subjects:One-hundred and fifteen non-obese freshmen in a Faculty of Medicine.Measurements:Anthropometric measurements, physical activity level, fitness level, food intake and lipid profile were recorded at predetermined intervals.Results:The control group gained weight, whereas the intervention group lost a slight amount of weight over 2 years. The difference between the two groups was 1.3 kg at the end of the follow-up, the trend of weight gain differing between the two groups during the 2-year intervention period (P=0.04). There was no detectable difference in fitness, physical activity level or total caloric intake between the two groups during follow-up. However, plasma triglyceride levels increased in the control group and decreased in the intervention group (P=0.04).Conclusion:In this randomized-controlled trial, a small-group seminar educational/behavioral intervention successfully prevents weight gain in normal weight young healthy university students. Such small absolute changes in body composition and lipid profile, if maintained over a prolonged period, could result in significant long-term health benefits for the general population (ClinicalTrial.gov registration number: NCT00306449).

Maternal and Cord-Blood Thyroid Hormone Levels and Exposure to Polybrominated Diphenyl Ethers and Polychlorinated Biphenyls During Early Pregnancy

Thyroid hormones play a critical role in the growth of many organs, especially the brain. Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) interact with the thyroid pathway and may disturb neurodevelopment. This prospective study was designed to examine associations between maternal blood PBDEs and PCBs in early pregnancy and levels of thyroid hormones in maternal and umbilical-cord blood. Levels of low-brominated PBDEs, 3 PCB congeners, total and free thyroid hormones (triiodothyronine (T3) and thyroxine (T4)), thyroid-stimulating hormone, thyroid peroxidase antibodies, iodine, selenium, and mercury were measured in 380 pregnant women in the first trimester who were recruited at the University Hospital Center of Sherbrooke (Quebec, Canada) between September 2007 and December 2008. Thyroid hormone levels were also assessed at delivery and in cord blood (n = 260). Data were analyzed on both a volume basis and a lipid basis. At less than 20 weeks of pregnancy, no relationship was statistically significant in volume-based analysis. In lipid-based models, an inverse association between maternal PBDEs and total T3 and total T4 and a direct association with free T3 and free T4 were observed. At delivery, in both analyses, we observed negative associations between maternal total T4, free T3, cord-blood free T4, and PBDEs and between maternal free T3 and PCBs. Our results suggest that exposure to PBDEs and PCBs in pregnancy may interfere with thyroid hormone levels.

Thyroid Function and Cognition during Aging.

We summarize here the studies examining the association between thyroid function and cognitive performance from an aging perspective. The available data suggest that there may be a continuum in which cognitive dysfunction can result from increased or decreased concentrations of thyroid hormones. Clinical and subclinical hypothyroidism as well as hyperthyroidism in middle-aged and elderly adults are both associated with decreased cognitive functioning, especially memory, visuospatial organization, attention, and reaction time. Mild variations of thyroid function, even within normal limits, can have significant consequences for cognitive function in the elderly. Different cognitive deficits possibly related to thyroid failure do not necessarily follow a consistent pattern, and L-thyroxine treatment may not always completely restore normal functioning in patients with hypothyroidism. There is little or no consensus in the literature regarding how thyroid function is associated with cognitive performance in the elderly.

Angiotensin II type 2 receptor promotes adipocyte differentiation and restores adipocyte size in high-fat/high-fructose diet-induced insulin resistance in rats.

This study was aimed at establishing whether specific activation of angiotensin II (ANG II) type 2 receptor (AT2R) modulates adipocyte differentiation and function. In primary cultures of subcutaneous (SC) and retroperitoneal (RET) preadipocytes, both AT2R and AT1R were expressed at the mRNA and protein level. Cells were stimulated with ANG II or the AT2R agonist C21/M24, alone or in the presence of the AT1R antagonist losartan or the AT2R antagonist PD123,319. During differentiation, C21/M24 increased PPARγ expression in both RET and SC preadipocytes while the number of small lipid droplets and lipid accumulation solely increased in SC preadipocytes. In mature adipocytes, C21/M24 decreased the mean size of large lipid droplets. Upon abolishment of AT2R expression using AT2R-targeted shRNAs, expressions of AT2R, aP2, and PPARγ remained very low, and cells were unable to differentiate. In Wistar rats fed a 6-wk high-fat/high-fructose (HFHF) diet, a significant shift toward larger adipocytes was observed in RET and SC adipose tissue depots. C21/M24 treatments for 6 wk restored normal adipocyte size distribution in both these tissue depots. Moreover, C21/M24 and losartan decreased hyperinsulinemia and improved insulin sensitivity impaired by HFHF diet. A strong correlation between adipocyte size area and glucose infusion rate during euglycemic-hyperinsulinemic clamp was observed. These results indicate that AT2R is involved in early adipocyte differentiation, while in mature adipocytes and in a model of insulin resistance AT2R activation restores normal adipocyte morphology and improves insulin sensitivity.

Thyroid Disruption by Low-Dose BDE-47 in Prenatally Exposed Lambs

The purpose of this study was to evaluate whether polybrominated diphenyl ethers (PBDE) at levels reported for human populations affect the thyroid state in pregnant sheep and lambs. Pregnant sheep were exposed to vehicle or BDE-47 (0.2, 2 and 20 μg/kg b.w.) from the 5th to 15th week of gestation by intravenous injections weekly. Thyroid hormone levels and BDE-47 content in the blood of sheep and lambs and adipose tissue were analyzed. We observed a significant decrease in total T4 and T3 in exposed lambs without any effect in pregnant sheep. Our finding indicates that prenatal low-dose PBDE exposure results in PBDE storage in fat of offspring and can affect thyroid metabolism in the developing fetus.

Effects of Lifestyle Interventions That Include a Physical Activity Component in Class II and III Obese Individuals: A Systematic Review and Meta-Analysis

Background In class II and III obese individuals, lifestyle intervention is the first step to achieve weight loss and treat obesity-related comorbidities before considering bariatric surgery. A systematic review, meta-analysis, and meta-regression were performed to assess the impact of lifestyle interventions incorporating a physical activity (PA) component on health outcomes of class II and III obese individuals. Methods An electronic search was conducted in 4 databases (Medline, Scopus, CINAHL and Sportdiscus). Two independent investigators selected original studies assessing the impact of lifestyle interventions with PA components on anthropometric parameters, cardiometabolic risk factors (fat mass, blood pressure, lipid and glucose metabolism), behaviour modification (PA and nutritional changes), and quality of life in adults with body mass index (BMI) ≥ 35 kg/m2. Estimates were pooled using a random-effect model (DerSimonian and Laird method). Heterogeneity between studies was assessed by the Cochran’s chi-square test and quantified through an estimation of the I ². Results Of the 3,170 identified articles, 56 met our eligibility criteria, with a large majority of uncontrolled studies (80%). The meta-analysis based on uncontrolled studies showed significant heterogeneity among all included studies. The pooled mean difference in weight loss was 8.9 kg (95% CI, 10.2–7.7; p < 0.01) and 2.8 kg/m² in BMI loss (95% CI, 3.4–2.2; p < 0.01). Long-term interventions produced superior weight loss (11.3 kg) compared to short-term (7.2 kg) and intermediate-term (8.0 kg) interventions. A significant global effect of lifestyle intervention on fat mass, waist circumference, blood pressure, total cholesterol, LDL-C, triglycerides and fasting insulin was found (p<0.01), without significant effect on HDL-C and fasting blood glucose. Conclusions Lifestyle interventions incorporating a PA component can improve weight and various cardiometabolic risk factors in class II and III obese individuals. However, further high quality trials are needed to confirm this evidence, especially beyond weight loss.

L-T3 preparation for whole-body scintigraphy : a randomized-controlled trial

Background  Patients with thyroid cancer often need whole‐body scintigraphy (WBS) under TSH stimulation after 4–6 weeks withdrawal from levothyroxine (L‐T4). Patients often become severely hypothyroid with impaired quality of life. Liothyronine (L‐T3) substitution is used empirically to prepare patients; however, no data exist to prove its benefit.

A cost-effective moderate-intensity interdisciplinary weight-management programme for individuals with prediabetes.

AIM To compare the effectiveness and cost of two lifestyle-modification programmes in individuals at high risk of developing type 2 diabetes. METHODS Forty-eight men and women with a body mass index ≥27 kg/m(2) and prediabetes were randomly assigned to either a 1-year interdisciplinary intervention including individual counseling every 6 weeks and 25 group seminars (group I; n=22) or a group intervention comprising seminars only (group G; n=26). These interventions were compared in terms of weight loss and improvement of anthropometric measures, metabolic variables and costs. RESULTS Participants in group I lost an average of 4.9 kg (95% CI: -7.3, -2.4; P<0.01) and 5 cm in waist circumference (95% CI: -7.0, -3.0; P<0.01), whereas no significant change was noted in those assigned to group G. Among the participants in group I, 50 and 27% lost at least 5 and 10% of their initial weight, respectively, compared with only 12 and 4%, respectively, in group G. Fasting glucose, 2-hour glucose and lipid profiles improved significantly in group I, and no participant (zero on 22) developed diabetes compared with 11.5% (3/26) in group G. Most participants (nine on 11) with impaired fasting glucose in group I returned to normal. The direct cost of the individual intervention was estimated to be

Does 2,2′,4,4′‐tetrabromodiphenyl ether interact directly with thyroid receptor?

733.06/year per subject compared with