Adiposity

This chapter is concerned with the intemperance of food and drink. Apposite to the painting by Hieronymus Bosch, we read in Le livre des bonnes moeurs ( The Book of Good Manners ) by the Augustinian Friar Jacques Legrand (Jacobus Magnus, ca. 1365-1425)  

There are several causes of adiposity. In animal experiments and in humans, genetic defects have recently been demonstrated to influence appetite control and adipogenesis. Such inherited dysregulations are however rather rare. Statistical investigations show that psychological, socio-economic and cultural factors contribute to adipogenesis. American studies document that individuals with poor education and low income are more prone to become overweight. 

How people plan and conduct their life and what attitude to life they adopt, are important indicators as to whether someone will ultimately develop adiposity. Hence, parents function as role models as well, and can have a decisive influence on the eating habits of their children (Fig. 5.104). 

104 Gluttony by Hieronymus Bosch from The Seven Deadly Sins and the Four Last Things . 

Over the years a plethora of natural product based medications, mainly of herbal origin, has been tried to treat adiposity. [241] Many ofthem are sold and used globally with veryhttle proof of efficacy or quality. The continued search for new therapies has revealed multiple targets to combat obesity. 

---

The growth of animals can be defined as an increase in mass of whole body, tissue(s), organ(s), or ceU(s) with time. This type of growth can be characterized by morphometric measurements eg, skeletal muscle or adipose tissue growth can be described by observing temporal changes in ceU number, ie, hyperplasia, and ceU size, ie, hypertrophy. Growth also includes developmental aspects of function and metaboHsm of cells and tissues from conception to maturity. 

Very Htfle data are available regarding effects of anaboHc steroid implants on the Hpid metaboHsm in growing mminants. Lipogenic enzyme activity and fatty acid synthesis in vitro were elevated in subcutaneous adipose tissue from bulls implanted with estradiol (44), which may account for the increase in fat content of carcasses reported in some studies. TBA implants have no effect on Hpogenesis in intact heifers, and only tend to reduce Hpogenic enzyme activities in ovariectomized heifers (45). 

Data for carcass composition corresponding to protein and lipid are percent-dissected skeletal muscle and adipose, respectively. 

The absorption of sulfonylureas from the upper gastrointestinal tract is faidy rapid and complete. The agents are transported in the blood as protein-bound complexes. As they are released from protein-binding sites, the free (unbound) form becomes available for diffusion into tissues and to sites of action. Specific receptors are present on pancreatic islet P-ceU surfaces which bind sulfonylureas with high affinity. Binding of sulfonylureas to these receptors appears to be coupled to an ATP-sensitive channel to stimulate insulin secretion. These agents may also potentiate insulin-stimulated glucose transport in adipose tissue and skeletal muscle. 

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). 

In order to define the obese state ia a clinical setting, it is necessary to have a means of estimating the amount of adipose (fat) tissue relative to lean body mass. Whereas highly accurate determiaations of body composition require complex laboratory procedures, large clinical studies typically employ measures of skia-fold thickness (11) or more commonly, body mass iadex (BMl) as a quantitative measure of obesity. 

The GI absorption of the dmg after po adrninistration is slow and variable with estimates ranging from 20—55%. Once absorbed, 96% of the dmg is bound to plasma proteins and other tissues on the body. Whereas peak plasma concentrations may be achieved in 3—7 h, the onset of antiarrhythmic action may occur in 2—3 days or more. This may result, in part, from distribution to and concentration of the dmg in adipose tissue, Hver, spleen, and lungs. Therapeutic plasma concentrations are 1—2 p.g/mL, although there appears to be no correlation between plasma concentration and antiarrhythmic activity. The plasma half-life after discontinuation of the dmg varies from 13—103 days. The dmg is metabolized in the Hver and the principal metaboHte is desethylamiodarone. The primary route of elimination is through the bile. Less than 1% of the unchanged dmg is excreted in the urine. The dmg can also be eliminated in breast milk and through the skin (1,2). 

Several studies have reported relatively high levels of PCBs in the semm or adipose tissues of occupationally-exposed individuals, eg, >3000 ppb in the semm (57,58). Not surprisingly, after these exposures were terminated, the PCB semm concentrations tended to decrease (59—61). 

Human exposure to environmental contaminants has been investigated through the analysis of adipose tissue, breast milk, blood and the monitoring of faecal and urinary excretion levels. However, while levels of persistent contaminants in human milk, for example, are extensively monitored, very little is known about foetal exposure to xenobiotics because the concentrations of persistent compounds in blood and trans-placental transmission are less well studied. Also, more information is needed in general about the behaviour of endocrine disruptive compounds (and their metabolites) in vivo, for example the way they bind to blood plasma proteins. 

Insulin is a peptide hormone, secreted by the pancreas, that regulates glucose metabolism in the body. Insufficient production of insulin or failure of insulin to stimulate target sites in liver, muscle, and adipose tissue leads to the serious metabolic disorder known as diabetes mellitus. Diabetes afflicts millions of people worldwide. Diabetic individuals typically exhibit high levels of glucose in the blood, but insulin injection therapy allows diabetic individuals to maintain normal levels of blood glucose. 

Fructose-6-phosphate generated in this way enters the glycolytic pathway directly in step 3, the second priming reaction. This is the principal means for channeling fructose into glycolysis in adipose tissue, which contains high levels of fructose. 

FIGURE 24.1 Scanning electron micrograph of an adipose cell (fat cell). Globules of triacylglycerols occupy most of the volume of such cells. (Prof. P. Motta, Dept, of Anatomy, University La Sapienza, Rome/Science Photo Library/Photo Researchers, Inc.)... 

Mobilization of Fats from Dietary Intake and Adipose Tissue... 

---