Publications

Familial influences were investigated for baseline sex hormone‐binding globulin (SHBG) and its response (post‐training minus baseline) to a 20‐week endurance exercise training program. One hundred, eighty‐four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex‐by‐generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h 2 = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE ( h 2 = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size. Am. J. Hum. Biol. 13:832–837, 2001. © 2001 Wiley‐Liss, Inc.

Computed tomography (CT) was used to study the association between adipose tissue localization and glucose tolerance in a sample of 52 premenopausal obese women aged 35.7 +/- 5.5 yr (mean +/- SD) and with a body fat of 45.9 +/- 5.5%. Body-fat mass and the body mass index (BMI) were significantly correlated with plasma glucose, insulin, and connecting peptide (C-peptide) areas after glucose (75 g) ingestion (.40 less than or equal to r less than or equal to .51, P less than .01). Trunk-fat accumulation and the size of fat cells in the abdomen displayed highly significant correlations with postglucose insulin levels. The C-peptide area was also positively correlated with abdominal fat cell size (r = .76, P less than .01) and was more closely associated with the sum of trunk skin folds (r = .59, P less than .001) than with the extremity skin folds (r = .29, P less than .05). Subcutaneous and deep-abdominal-fat areas measured by CT displayed comparable associations with the plasma insulin area (r = .44 and .49, respectively; P less than .001) but marked differences in the associations with glucose tolerance. Indeed, subcutaneous abdominal fat was not significantly correlated with the glucose area, whereas deep abdominal fat showed a significant correlation (r = .57, P less than .001) with the glucose area. Midthigh fat deposition measured by CT was not, however, correlated with plasma glucose, insulin, or C-peptide areas.(ABSTRACT TRUNCATED AT 250 WORDS)

ARDERN, C. I., P. T. KATZMARZYK, I. JANSSEN, A. S. LEON, J. H. WILMORE, J. S. SKINNER, D. C. RAO, J.-P. DESPRÉS, T. RANKINEN, and C. BOUCHARD. Race and Sex Similarities in Exercise-Induced Changes in Blood Lipids and Fatness. Med. Sci. Sports Exerc., Vol. 36, No. 9, pp. 1610–1615, 2004. Purpose: This study explores sex and race differences in the association between changes in fat mass (FM), abdominal visceral fat (AVF), and abdominal subcutaneous fat (ASF) on blood lipid changes consequent to aerobic exercise training. Methods: The sample included 613 participants (428 white and 185 black, 46% men) from the HERITAGE Family Study. Total FM was determined by densitometry, whereas AVF and ASF cross-sectional areas were determined by computed tomography at the L4–L5 level. Blood lipid measurements included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and the TC/HDL-C ratio, which were obtained before and after 20 wk of supervised aerobic exercise. Canonical correlation was used to determine the multivariate associations between body fatness and blood lipids at baseline and the changes induced by exercise training. Results: Body fat accounted for 26–36% of the variance in baseline blood lipids, and changes in body fat accounted for 7–21% of the variance in changes in blood lipids with exercise training. The pattern of loadings indicated similar relationships between body fatness and blood lipids at baseline, and their respective changes with exercise training among the four sex-by-race groups. Greater fat loss, characterized by loss of FM, AVF, and ASF, was associated with a greater blood lipid response characterized by an increase in HDL-C and decreases in LDL-C, TG, TC, and TC/HDL-C. Although the pattern of loadings was similar in all groups, the strength of the association was stronger in blacks than in whites. Conclusion: The multivariate associations among fat loss and changes in blood lipids consequent to aerobic exercise training are similar in black and white men and women.

Homozygosity has long been associated with rare, often devastating, Mendelian disorders, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10-300, 2.1 × 10-6, 2.5 × 10-10 and 1.8 × 10-10, respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months' less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection, this study provides evidence that increased stature and cognitive function have been positively selected in human

OBJECTIVE To study the associations between changes in body fatness, visceral adipose tissue (AT), and indexes of plasma glucose-insulin homeostasis over a 7-year follow-up period. RESEARCH DESIGN AND METHODS A sample of 30 nondiabetic women aged 35.2 ± 5.6 (SD) years at baseline was studied. RESULTS Changes in visceral AT and in subcutaneous AT (measured by computed tomography) as well as changes in body fat mass (obtained by hydrostatic weighting) were significantly related to changes in fasting plasma insulin levels and in plasma insulin area measured after a 75-g oral glucose load (0.47 ≤ r ≤ 0.62; P &amp;lt; 0.01). Changes in visceral AT but not in body fat mass or in subcutaneous AT area were significantly associated with changes in plasma glucose area (r = 0.37; P &amp;lt; 0.05). When two subgroups of women with similar mean increases in body fat mass but with either small or large increases in visceral AT were compared, the subgroup with the largest gain in visceral AT showed the greatest deterioration in indexes of plasma glucose-insulin homeostasis. On the other hand, when two subgroups with similar mean increases in visceral AT but with different changes in body fat mass were compared, both subgroups showed similar changes in plasma glucose and insulin concentrations. CONCLUSIONS Results of this 7-year follow-up study in women suggest that changes in indexes of plasma glucose-insulin homeostasis are significantly associated with changes in visceral AT, even after control for changes in body fat mass.

No abstract is provided for this article.

No abstract is provided for this article.

The reproducibility of a 3-day dietary record was investigated in 61 subjects including adults and children of both sexes. The subjects completed two records within an interval of 7 days. The agreement of the records was moderate to high for almost all nutrients, with the exception of retinol intake for which very low intraclass correlation coefficients were noted. Sex did not influence the reproducibility of nutritional intake measurement. However, children reported more stable intakes than adults. These results suggest that a 3-day dietary record provides reliable estimates of the intake of almost all nutrients, particularly in children.

No abstract is provided for this article.

No abstract is provided for this article.

The relationship between lipid peroxidation (plasma malondialdehyde [MDA] concentration) and plasma fibrinogen level was analyzed in 144 men, aged 53–62 years. MDA was measured colorimetrically and fibrinogen with the thrombin method. Mean plasma MDA concentration was 12.6 (SD 1.2) μmol/L, plasma fibrinogen level 2.91 (0.47) g/L, and body mass index 27.1 (3.5) kg/m2. Prevalence of smoking was 17%. MDA correlated moderately with fibrinogen r=0.45, p<0.001 . Both MDA and fibrinogen correlated positively with waist hip ratio (WHR) r=0.36 and r=0.38, p< 0.001 for both and blood leukocyte count r=0.36 and r=0.45, p<0.001 , but inversely with VO 2 max r=−0.23, P=0.005; r=−0.41, p<0.001 . Both MDA and fibrinogen levels were higher in smokers than in non-smokers (p<0.01). In multiple stepwise regression analysis, plasma MDA, VO2max, smoking, and leukocyte count explained 38.1% of the variance in plasma fibrinogen level, with the individual contributions reaching 20.6%, 9.7%, 5.5%, and 2.3%, respectively. WHR, serum triglycerides, and age did not enter the model. These data suggest that increased lipid peroxidation is associated with elevated plasma fibrinogen level in middle-aged men.