Adipose tissue aging

Reports have appeared in the Hterature of the use of human growth hormone in older men. It has been proposed that a reduction in growth hormone in old age is responsible for increased adipose tissue, loss of lean body mass, and thinning of skin. Current studies conducted on older men indicate the hormone reverses these effects. In the parameters studied the patients resembled those of persons 10 —20 years younger (70). 

PCDD/PCDFs accumulate in human adipose tissue, and the level reflects the history of intake by the individual. Several factors have been shown to affect adipose tissue concentrations/body burdens, notably age, the number of children and period of breastfeeding, and dietary habits. Breast-milk represents the most useful matrix for evaluating time trends of dioxins and many other POPs. Several factors affect the PCDD/PCDFs content of human breast-milk, most notably the mothers age, the duration of breast-feeding and the fat content of the milk. Studies should therefore ideally... 

Tissue levels of chloroform obtained at autopsy reflected environmental exposure levels in other studies. The levels ranged from 20 to 49 pg/kg of chloroform from adipose tissue extracted into hexane from samples taken from 10 individuals in Florida (Peoples et al. 1979). In 30 autopsy cases in Germany, the adipose tissue contained amean of 23.4 pg/kg wet tissue 24.8 pg/kg perinephric fat 10.8 pg/kg liver tissue 9.9 pg/kg lung tissue and 10 pg/kg muscle tissue (Alles et al. 1988). The maximum chloroform content increased with age and was not dependent on the volume of fat in the tissues. 

Detection of heptachlor or heptachlor epoxide may indicate either recent or past exposure. Heptachlor epoxide has a long half-life, particularly in adipose tissue, because it is very lipophilic and can remain for months to years. However, it is eventually mobilized into the serum and subsequently to the liver for further breakdown. Blood serum levels are often taken to indicate a more recent exposure, but heptachlor epoxide does become mobilized into the serum after being stored in adipose tissue for substantial periods. Thirty-five human adipose tissue samples were obtained during autopsy between 1987 and 1988 from residents of north Texas. In 97% of these samples, there were measurable levels of heptachlor epoxide that were positively correlated with age for the age groups 41 -60 years and >61 years. No differences between sexes were noted. These results indicate that levels of heptachlor epoxide in human tissues from this region have not significantly decreased since 1970 (Adeshina and Todd 1990). 

Polybrominated Biphenyls. Twenty-five workers at a PBB-manufacturing plant (exposure duration and levels not reported) displayed mean scores on tests of memory and learning that were typical for people of their age, and educational, occupational, and cultural backgrounds, even though they had an elevated mean PBB concentration in adipose tissue (9.33 ppm) (Brown et al. 1981). Workers with the highest concentrations of PBBs in adipose tissue showed no evidence of memory dysfunction in these tests. 

The second case-control study from Norway (Biong et ah, 2006) was published in 2006. In this study, 112 myocardial infarction cases and 107 controls were enrolled. Subcutaneous adipose tissue samples were drawn within 4 days of the myocardial infarction and the fatty acid composition of the adipose tissue was analyzed. The study reported that the proportion of 15 0 in adipose tissue was inversely related to the risk of a first myocardial infarction. Also, other fatty acids (14 0, 14 1, and 17 1) associated with the intake of milk fat were inversely related to a first myocardial infarction. Most of these relationships remained (all except between 14 0 and MI) after adjustment for age, sex, waist-to-hip ratio, smoking, and family history of CHD. 

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