Suivi physique et densitométrique aux rayons X des effets sur l'os de la chlortétracycline chez le porc

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Effect of polymorphisms in the PPARGC1A gene on body fat in Asian Indians

OBJECTIVE: To evaluate whether polymorphisms in the peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PPARGC1A) gene were related to body fat in Asian Indians. METHODS: Three polymorphisms of PPARGC1A gene, the Thr394Thr, Gly482Ser and +A2962G, were genotyped on 82 type 2 diabetic and 82 normal glucose tolerant (NGT) subjects randomly chosen from the Chennai Urban Rural Epidemiology Study using PCR-RFLP, and the nature of the variants were confirmed using direct sequencing. Linkage disequilibrium (LD) was estimated from the estimates of haplotypic frequencies using an expectation-maximization algorithm. Visceral, subcutaneous and total abdominal fat were measured using computed tomography, whereas dual X-ray absorptiometry was used to measure central abdominal and total body fat. RESULTS: None of the three polymorphisms studied were in LD. The genotype (0.59 vs 0.32, P=0.001) and allele (0.30 vs 0.17, P=0.007) frequencies of Thr394Thr polymorphism were significantly higher in type 2 diabetic subjects compared to those in NGT subjects. The odds ratio for diabetes (adjusted for age, sex and body mass index) for the susceptible genotype, XA (GA+AA) of Thr394Thr polymorphism, was 2.53 (95% confidence intervals: 1.30-5.04, P=0.009). Visceral and subcutaneous fat were significantly higher in NGT subjects with XA genotype of the Thr394Thr polymorphism compared to those with GG genotype (visceral fat: XA 148.2+/-46.9 vs GG 106.5+/-51.9 cm(2), P=0.001; subcutaneous fat: XA 271.8+/-167.1 vs GG 181.5+/-78.5 cm(2), P=0.001). Abdominal (XA 4521.9+/-1749.6 vs GG 3445.2+/-1443.4 g, P=0.004), central abdominal (XA 1689.0+/-524.0 vs GG 1228.5+/-438.7 g, P<0.0001) and non-abdominal fat (XA 18763.8+/-8789.4 vs GG 13160.4+/-4255.3 g, P<0.0001) were also significantly higher in the NGT subjects with XA genotype compared to those with GG genotype. The Gly482Ser and +A2962G polymorphisms were not associated with any of the body fat measures. CONCLUSION: Among Asian Indians, the Thr394Thr (G --> A) polymorphism is associated with increased total, visceral and subcutaneous body fat.

Visceral and central abdominal fat and anthropometry in relation to diabetes in Asian Indians

OBJECTIVE: The objective of the study was to examine body fat distribution using computed tomography (CT), dual-energy X-ray absorptiometry (DEXA), and anthropometry in relation to type 2 diabetes in urban Asian Indians. RESEARCH DESIGN AND METHODS: This is a case-control study of 82 type 2 diabetic and 82 age- and sex-matched nondiabetic subjects from the Chennai Urban Rural Epidemiology Study, an ongoing epidemiological study in southern India. Visceral, subcutaneous, and total abdominal fat were measured using CT, while DEXA was used to measure central abdominal and total body fat. Anthropometric measures included BMI, waist circumference, sagittal abdominal diameter (SAD), and waist-to-hip ratio. RESULTS: Visceral and central abdominal fat showed a strong correlation with each other (P <0.0001), and kappa analysis revealed a fairly good agreement between tertiles of visceral and central abdominal fat (kappa=0.44, P <0.0001). Diabetic subjects had significantly higher visceral (P=0.005) and central abdominal (P=0.011) fat compared with nondiabetic subjects. Waist circumference and SAD showed a strong correlation with visceral (P <0.01) and central abdominal (P <0.0001) fat in both diabetic and nondiabetic subjects. Logistic regression analysis revealed visceral (odds ratio [OR] 1.011, P=0.004) and central abdominal (OR 1.001, P=0.013) fat to be associated with diabetes, even after adjusting for age and sex. CONCLUSIONS: Visceral and central abdominal fat showed a strong association with type 2 diabetes. Both measures correlated well with each other and with waist circumference and SAD in diabetic and nondiabetic urban Asian Indians.

Influence of body composition on bone mass in postmenopausal osteoporotic women

We aimed at evaluating the relationship of lean and fat mass to bone mass in osteoporotic postmenopausal women. We invited 65 women who were being treated at the Sao Paulo Hospital osteoporosis outpatients` clinic to participate. Body composition and bone mineral density (BMD) measurements were performed using Dual-energy X-ray absorptiometry methodology (DXA). The mean age and weight were 69.7 +/- 6.4 years and 56.3 +/- 7.6 kg, respectively. Accordingly to the body mass index (BMI), 52.8% were of normal weight and 47.1% of the patients were overweight. Overweight women had significantly higher bone mass. Similarly, skeletal muscle index (SMI) showed a positive effect on BMD measurements and women with sarcopenia had significantly lower BMD measurements in total femur and femoral neck. In multiple regression analysis only lean mass and age, after adjustments to fat mass and BMI, were able to predict total body bone mineral content (BMC) (R(2) = 28%). Also lean mass adjusted to age and BMI were able to predict femoral neck BMD (R(2) = 14%). On the other hand, none of the components of the body composition (lean mass or fat mass) contributed significantly to explaining total femur BMD and neither body composition measurements were associated with spine BMD. These findings suggest that lean mass has a relevant role in BMC and BMD measurements. In addition, lower BMI and lean mass loss (sarcopenia) is associated to lower BMC and BMD of femoral neck and total femur and possible higher risk of osteoporotic fracture. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Calcium intake and its relationship with adiposity and insulin resistance in post-pubertal adolescents

Background Dietary calcium intake has been described as being a negative contributor to adiposity. In adolescents, this relationship is not well established. The objectives of the present study were to compare the calcium intake of normal-weight and obese adolescents and to evaluate its relationship with adiposity and insulin resistance. Methods A cross-sectional analysis of 96 post-pubertal adolescents; 47 normal weight and 49 obese, mean age 16.6 (SD +/- 1.3) years. Body composition was assessed by dual-energy X-ray absorptiometry. Dietary intake was evaluated using a 3-day dietary record. The biochemical evaluation comprised the measurements of serum lipids, lipoproteins, glucose and insulin. Insulin resistance was calculated using the Homeostasis Model Assessment of Insulin resistance (HOMA-IR). Results The mean calcium intake, adjusted for energy, was lower in obese adolescents, 585.2 (+/- 249.9) mg, than in normal weight adolescents, 692.1 (+/- 199.5) mg. Only 4% of adolescents had an adequate intake of calcium. Calcium intake was inversely associated with body trunk fat, insulin and HOMA-IR in the obese group. The quartile analysis of calcium intake provided evidence that girls in the highest quartile had decreased adiposity and insulin resistance. Conclusions This study showed a negative relationship between calcium intake and body fat and insulin resistance, mainly in obese girls, and demonstrates the importance of an increased dietary calcium intake.

Prevalence and risk factors of radiographic vertebral fracture in Brazilian community-dwelling elderly

The prevalence and risk factors of radiographic vertebral fracture were determined among Brazilian community-dwelling elderly. Vertebral fractures were a common condition in this elderly population, and lower hip bone mineral density was a significant risk factor for vertebral fractures in both genders. The aim of the study was to estimate the prevalence of radiographic vertebral fracture and investigate factors associated with this condition in Brazilian community-dwelling elderly. This cross-sectional study included 943 elderly subjects (561 women and 382 men) living in So Paulo, Brazil. Thoracic and lumbar spine radiographs were obtained, and vertebral fractures were evaluated using Genant`s semiquantitative method. Bone mineral density (BMD) was measured by dual X-ray absorptiometry, and bone biochemical markers were also evaluated. Female and male subjects were analyzed independently, and each gender was divided into two groups based on whether vertebral fractures were present. The prevalence of vertebral fracture was 27.5% (95% CI 23.8-31.1) in women and 31.8% in men (95% CI 27.1-36.5) (P = 0.116). Cox regression analyses using variables that were significant in the univariate analysis showed that age (prevalence ratio = 1.03, 95% CI 1.01-1.06; p = 0.019) and total femur BMD (PR = 0.27, 95% CI 0.08-0.98; p = 0.048) were independent factors in predicting vertebral fracture for the female group. In the male group, Cox regression analyses demonstrated that femoral neck BMD (PR = 0.26, 95% CI 0.07-0.98; p = 0.046) was an independent parameter in predicting vertebral fractures. Our results suggest that radiographic vertebral fractures are common in Brazilian community-dwelling elderly and that a low hip BMD was an important risk factor for this condition in both genders. Age was also significantly correlated with the presence of vertebral fractures in women.

Genetic variation and obesity in Australian women: A prospective study.

Objective: A number of candidate genes have been implicated in the pathogenesis of obesity in humans. This study examines associations between longitudinal changes in body mass and composition and the presence of polymorphisms in the ß-3 adrenergic receptor, tumor necrosis factor-α, leptin, and leptin receptor (Lepr) in a cohort of Australian women.

Research Methods and Procedures: Healthy white Australian women (n = 335) were randomly selected from the Barwon region of Victoria and underwent baseline anthropometry and double-energy X-ray absorptiometry for assessment of body mass and adiposity. These measurements were repeated again at 2-year follow-up. Genomic DNA was extracted and used for polymerase chain reaction-based genotyping of all polymorphisms.

Results: The Pro1019Pro Lepr polymorphism was associated with longitudinal increases in body weight (p = 0.02), fat mass (p = 0.05), and body mass index (p = 0.01) in this study, and individuals homozygous for the A allele at this locus had a greater propensity to gain body fat over time. The largest effects on body composition seemed to be in individuals already obese at baseline. Changes in body weight, fat mass, percent body fat, and body mass index over a 2-year period were not associated with genetic variation in the ß-3 adrenergic receptor (Trp64Arg), tumor necrosis factor-α promoter, or leptin genes in non-obese or obese women.

Discussion: These results suggest that a Lepr polymorphism is involved in the regulation of body mass and adiposity in obese Australian white women, which may have implications for the treatment of obesity in this population.

Lifetime sport and leisure activity participation is associated with greater bone size, quality and strength in older men

Introduction: It remains uncertain whether long-term participation in regular weight-bearing exercise confers an advantage to bone structure and strength in old age. The aim of this study was to investigate the relationship between lifetime sport and leisure activity participation on bone material and structural properties at the axial and appendicular skeleton in older men (>50 years).

Methods: We used dual-energy X-ray absorptiometry (DXA) to assess hip, spine and ultradistal (UD) radius areal bone mineral density (aBMD) (n=161), quantitative ultrasound (QUS) to measure heel bone quality (n=161), and quantitative computed tomography (QCT) to assess volumetric BMD, bone geometry and strength at the spine (L₁–L₃) and mid-femur (n=111). Current (>50+ years) and past hours of sport and leisure activity participation during adolescence (13–18 years) and adulthood (19–50 years) were assessed by questionnaire. This information was used to calculate the total time (min) spent participating in sport and leisure activities and an osteogenic index (OI) score for each participant, which provides a measure of participation in weight-bearing activities.

Results: Regression analysis revealed that a greater lifetime (13–50+ years) and mid-adulthood (19–50 years) OI, but not total time (min), was associated with a greater mid-femur total and cortical area, cortical bone mineral content (BMC), and the polar moment of inertia (I _p) and heel VOS (p ranging from <0.05 to <0.01). These results were independent of age, height (or femoral length) and weight (or muscle cross-sectional area). Adolescent OI scores were not found to be significant predictors of bone structure or strength. Furthermore, no significant relationships were detected with areal or volumetric BMD at any site. Subjects were then categorized into either a high (H) or low/non-impact (L) group during adolescence (13–18 years) and adulthood (19–50+ years) according to their OI scores during each of these periods. Three groups were subsequently formed to reflect weight-bearing impact categories during adolescence and then adulthood: LL, HL and HH. Compared to the LL group, mid-femur total and cortical area, cortical BMC and I _p were 6.5–14.2% higher in the HH group. No differences were detected between the LL and HL groups.

Conclusions: In conclusion, these findings indicate that long-term regular participation in sport and leisure activities categorized according to an osteogenic index [but not the total time (min) spent participating in all sport and leisure activities] was an important determinant of bone size, quality and strength, but not BMD, at loaded sites in older men. Furthermore, continued participation in weight-bearing exercise in early to mid-adulthood appears to be important for reducing the risk of low bone strength in old age.

Angiotensin converting enzyme inhibition from birth reduces body weight and body fat in Sprague-Dawley rats

In vitro studies have demonstrated that angiotensin II (ANG II) induces adipocyte hyperplasia and hypertrophy. The aim of the present study was to determine the effect of angiotensin-converting enzyme inhibition on body weight, adiposity and blood pressure in Sprague–Dawley rats. From birth half of the animals (n = 15) were given water to drink, while the remainder were administered perindopril in their drinking water (2 mg/kg/day). Food intake, water intake and body weight were measured weekly. Blood pressure was measured by tail cuff plethysmography at 11-weeks. Body fat content and distribution were assessed using dual energy X-ray absorptiometry and Magnetic Resonance Imaging at 12 weeks. Animals administered with perindopril had a body fat proportion that was half that of controls. This was consistent with, but disproportionately greater than the observed differences in food intake and body weight. Perindopril treatment completely removed hypertension. We conclude that the chronic inhibition of ANG II synthesis from birth specifically reduces the development of adiposity in the rat.

Changes in body composition as determinants of longitudinal changes in bone mineral measures in 8 to 26 year old female twins

Between 1990 and 1998, we conducted a longitudinal study of 286 female twins aged 8 to 25 years at baseline (60 monozygotic (MZ) pairs, 44 dizygotic (DZ) pairs and 78 unpaired twins), measured on average 2.4 times (range 2–6) with an average of 1.8 years between measurements (range 0.7–6.7 years). Areal bone mineral density (ABMD) at the lumbar spine, total hip and femoral neck, total body bone mineral content (BMC), total body soft tissue composition (lean mass and fat mass) were measured by dual-energy X-ray absorptiometry, and height and menarchial status were also recorded. Median annual changes in height were negligible at 4 years post-menarche. During the “linear growth” period up to 4 years post-menarche, ABMD at the lumbar spine, total hip and femoral neck increased with annual change in lean mass by 1.7 (S.E. 0.1), 1.4 (0.1) and 1.0 (0.1) percent per kilogram per year, respectively (all p<0.001), independently of changes in fat mass or height. During the “post-linear growth” period, ABMD at the total hip and femoral neck increased with annual change in fat mass by 0.3 (0.1) and 0.5 (0.1) percent per kilogram per year (all p<0.01), independent of change in lean mass. Annual changes in total body BMC were associated with annual changes in lean mass (1.9 (0.2) percent per kilogram), in fat mass (1.3 (0.2) percent per kilogram) and in height (0.7) (0.2) percent per centimeter) during linear growth, and in fat mass (1.0 (0.1)) and lean mass (0.6 (0.1)) percent per kilogram post-linear growth (all p<0.001). We conclude that changes in bone mineral measures are strongly associated with changes in lean mass during linear growth, while post-linear growth, changes in fat mass are the predominant, although weaker, predictor. These findings suggest that the strong cross-sectional association between bone mineral measures and lean mass is established during growth and development, and that fat mass emerges as a more powerful determinant of bone change in healthy adult females.

Benefits of a year-long workplace weight loss program on cardiovascular risk factors

Objective: To assess the effectiveness of a year-long workplace weight loss program in reducing risk factors of coronary heart disease.

Design: A randomised, controlled study of low fat (25% of dietary energy) diet- and/or moderate exercise-induced weight loss interventions in free-living, middle-aged men. Compliance was monitored from food and activity diaries at monthly blood pressure measurement sessions. Blood was sampled and body composition determined from dual energy X-ray absorptiometry before and after 12 months.

Subjects and setting: Fifty-eight overweight men (mean [+ or -] SD age: 43.4 [+ or -] 5.7 years; BMI 29.0 [+ or -] 2.6 kg/[m.sup.2]), recruited from a national corporation, were instructed into diet (n = 18) exercise (a 21) or control (n = 19) groups over 12 months; 16 control subjects combined diet and exercise (n = 16) for the subsequent 12 months.

Main outcome measures: At 12 months, weight, total and regional fat and lean mass, dietary energy and percentage dietary fat intake, physical activity indices, systolic and diastolic blood pressure, serum insulin, blood lipids and lipoproteins.

Statistical analyses: Differences between groups were tested using analysis of variance with Scheffe post hoc test. Differences between pre- and post-intervention variables were tested using Students' paired t-tests. Pearson's correlation coefficient and univariate linear regression identified association between dependent variables, multiple stepwise regression identified specific predictors.

Results: Weight loss with either diet or exercise resulted in a reduction in systolic blood pressure (-3.3 [+ or -] 1.7%), diastolic blood pressure (-4.8 [+ or -] 1.3%) and LDL cholesterol (-3.9 [+ or -] 2.8%), a rise in HDL cholesterol (+10.0 [+ or -] 3.8%) and a change in the LDL/HDL ratio (-8.9 [+ or -] 3.5%). Abdominal fat loss (-26.8 [+ or -] 3.6% after diet; -16.6 [+ or -] 4.5% after exercise; -21.0 [+ or -] 4.7% after diet and exercise) was the strongest predictor of change in blood pressure: twenty percent abdominal fat loss predicted a percentage fall of 2.4 [+ or -] 0.05% in systolic blood pressure and 5.4 [+ or -] 0.07% in diastolic blood pressure. Greater abdominal fat loss was associated with the greatest decrease in serum insulin (P < 0.05).

Conclusion: Modest changes in diet and exercise effected by a low cost workplace-based education program achieved weight loss, loss of abdominal fat, reduced blood pressure and serum insulin and improved blood lipid concentrations. (Nutr Diet 2002;59:87-96)

Body size, body composition, and fat distribution: a comparison of young New Zealand men of European, Pacific Island, and Asian Indian ethnicities

Aims To investigate body size and body fat relationships and fat distribution in young healthy men drawn from New Zealand European, Pacific Island, and Asian Indian populations.
Method A total of 114 healthy men (64 European, 31 Pacific Island, 19 Asian Indian) aged 17–30 years underwent measurements of height, weight, and body composition by total body dual-energy X-ray absorptiometry (DXA). Body mass index (BMI) was then calculated. Percent body fat (%BF), fat-free mass, bone mineral content, bone mineral density, abdominal fat, thigh fat, and appendicular skeletal muscle mass (ASMM) were obtained from the DXA scans.
Results For the same BMI, %BF for Pacific Island men was 4% points lower and for Asian Indian men was 7–8% points higher compared to Europeans. Compared to European men for the same %BF, BMI was 2–3 units higher for Pacific Island, and 3–6 units lower for Asian Indian. The ratio of abdominal fat to thigh fat, adjusted for height, weight, and %BF, was significantly higher for Asian Indian men than European (p=0.022) and Pacific Island (p=0.002) men. ASMM, adjusted for height and weight, was highest in Pacific Island and lowest in Asian Indian men.
Conclusions The relationship between %BF and BMI is different for European, Pacific Island, and Asian Indian men which may, at least in part, be due to differences in muscularity. Asian Indians have more abdominal fat deposition than their European and Pacific Island counterparts. Use of universal BMI cut-off points are not appropriate for comparison of obesity prevalence between these ethnic groups.

Peripheral quantitative computed tomography in children and adolescents : the 2007 ISCD pediatric official positions

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society
of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the
pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.

The skeletal benefits of calcium- and vitamin D3-fortified milk are sustained in older men after withdrawal of supplementation: an 18 mo follow-up study

Background: In a previous 2-y randomized controlled trial, we showed that calcium- and vitamin D₃–fortified milk stopped or slowed bone loss at several clinically relevant skeletal sites in older men.

Objective: The present study aimed to determine whether the skeletal benefits of the fortified milk were sustained after withdrawal of the supplementation.

Design: One hundred nine men >50 y old who had completed a 2-y fortified milk trial were followed for an additional 18 mo, during which no fortified milk was provided. Bone mineral density (BMD) of the total hip, femoral neck, lumbar spine, and forearm was measured by using dual-energy X-ray absorptiometry.

Results: Comparison of the mean changes from baseline between the groups (adjusted for baseline age, BMD, total calcium intake, and change in weight) showed that the net beneficial effects of fortified milk on femoral neck and ultradistal radius BMD at the end of the intervention (1.8% and 1.5%, respectively; P < 0.01 for both) were sustained at 18-mo follow-up (P < 0.05 for both). The nonsignificant between-group differences at the total hip (0.8%; P = 0.17) also persisted at follow-up (0.7%; P = 0.10), but there were no lasting benefits at the lumbar spine. The average total dietary calcium intake in the milk supplementation group at follow-up approximated recommended amounts for Australian men >50 y old (1000 mg/d) but did not differ significantly from that in the control subjects (1021 versus 890 mg/d).

Conclusion: Supplementation with calcium- and vitamin D₃–fortified milk for 2 y may provide some sustained benefits for BMD in older men after withdrawal of supplementation.

Selective reduction in body fat mass and plasma leptin induced by angiotensin-converting enzyme inhibition in rats

Objective: There is emerging evidence that angiotensin stimulates adipocyte differentiation and lipogenesis. This study tested the hypothesis that inhibition of angiotensin II by treatment with an angiotensin-converting enzyme inhibitor, perindopril, would reduce fat mass in rats. Design: After a 12-day baseline, rats were divided into two groups: one was untreated and the other received perindopril (1.2 mg kg⁻¹ per day) in drinking water for 26 days.Subjects: In total, 16 male Sprague–Dawley rats aged 10 weeks at the start of the study. Measurements: Plasma leptin was measured in samples collected at baseline, half-way through and at the end of treatment. Body weight, food and water intake were measured daily throughout the experiment. Body fat mass, bone and lean mass were determined by dual energy X-ray absorptiometry (DEXA) at the end of the treatment period. Results: Daily food intake was the same in both groups throughout the study. By the end of treatment, animals receiving perindopril showed a modest reduction in weight gain relative to the untreated animals (62.4±5.0 g vs 73.0±4.0 g; P<0.05). DEXA analysis showed that body composition was greatly altered and the perindopril-treated group had 26% less body fat mass than the untreated group (61.0±5.2 g vs 44.4±4.2 g; P<0.01). The reduction in body fat mass was correlated with reductions in the weight of both the epididymal and retroperitoneal fat pads (P<0.001). Similarly, plasma leptin was reduced by perindopril treatment (4.64±0.56 ng ml⁻¹) compared to the untreated group (8.27±1.03 ng ml⁻¹; P<0.001). In contrast, there were no differences in lean or bone mass between the two groups.Conclusion: Oral treatment with perindopril selectively reduced body fat mass without influencing daily food intake. In contrast, there were no differences in lean or bone mass between the two groups