Body fat content

Leptin is a cytokine produced and secreted by adipose tissue in proportion to the body fat content [3]. Mice and humans lacking leptin or its receptor develop a severe hyperphagia and a dramatic degree of obesity which is considerably more pronounced than that of the NDRKO mouse. Thus, leptin is the key adiposity signal in rodents and humans. Leptin secretion appears to reflect the metabolic status of the adipocyte rather than the sheer size of triglyceride deposits, and leptin levels may transiently be dissociated from total body fat. Nonetheless, over the course of a day with unrestricted food supply, plasma leptin levels reliably reflect the amount of total body fat. Local administration of leptin into the brain results in reduced food intake. The vast majority of patients with obesity have elevated serum levels of leptin. Thus, it is believed that the polygenic obesity is due to leptin resistance rather than to inadequate leptin secretion, or to a reduced blood/brain transport of the cytokine. 

Sato et al. (1991) expanded their earlier PBPK model to account for differences in body weight, body fat content, and sex and applied it to predicting the effect of these factors on trichloroethylene metabolism and excretion. Their model consisted of seven compartments (lung, vessel rich tissue, vessel poor tissue, muscle, fat tissue, gastrointestinal system, and hepatic system) and made various assumptions about the metabolic pathways considered. First-order Michaelis-Menten kinetics were assumed for simplicity, and the first metabolic product was assumed to be chloral hydrate, which was then converted to TCA and trichloroethanol. Further assumptions were that metabolism was limited to the hepatic compartment and that tissue and organ volumes were related to body weight. The metabolic parameters, (the scaling constant for the maximum rate of metabolism) and (the Michaelis constant), were those determined for trichloroethylene in a study by Koizumi (1989) and are presented in Table 2-3. 

Metabolic differences betw een humans and other animals may account for some of the interspecies differences in specific organ toxicity of trichloroethylene (see below). Among humans, sexual differences due mainly to the effects of body fat content on trichloroethylene absorption are expected based on PBPK modeling (see Section 2.3.5). 

Uncoupling protein expression. Oil, administered to female Wistar rats fed ad libitum a high-fat diet with coconut oil for 7 weeks, promoted an increase in body fat content, body weight, and uncoupling protein levels. At the completion of experiment 1, oil was administered to high-fat diet rats for 3 weeks. Adipose depots were strongly reduced in the rats fed the high fat... 

Candidates must be in excellent health and have no conditions that would restrict their ability to safely do fire suppression and rescue work. Weight (body fat content) must be proportionate to height for men and women. Uncorrected distance visual acuity of at least 20/100 in the poorer eye and 20/40 in the better eye, correctable to at least 20/40 in one eye and 20/20 in the other eye, is required. Regarding refractive surgery, most persons who have had these procedures will be passed. However, some may be deferred for several months or disqualified based on an individualized assessment of the surgical outcome. Color vision Candidates must be able to accurately and quickly name colors and must be free of other visual impairments that would restrict the ability to perform firefighter duties. 

Candidates must be in excellent health and have no conditions that would restrict their ability to safely do fire suppression and rescue work Weight (body fat content) must be proportionate to height for men and women... 

DeLany, J. P., Blohm, F., Truett, A. A., Scimeca, J. A., and West, D. B. (1999). Conjugated linoleic acid rapidly reduces body fat content in mice without affecting energy intake. Am.. Physiol. 276, R1172-R1179. 

Leung et al. (1988) varied the fat content parameter in the C57BL/6J mice from 3 to 12% of body weight. The rationale was that the difference in hepatic concentration may have been due to greater capacity of the DBA/2J mouse to sequester the highly lipophilic 2,3,7,8-TCDD in adipose tissue. However, the results showed that 2,3,7,8-TCDD concentration in the liver was relatively insensitive to body fat content, indicating that this was not an important factor influencing the disposition of 2,3,7,8-TCDD in... 

Benzene was rapidly distributed throughout the bodies of dogs exposed via inhalation to concentrations of 800 ppm for up to 8 hours per day for 8-22 days (Schrenk et al. 1941). Fat, bone marrow, and urine contained about 20 times the concentration of benzene in blood benzene levels in muscles and organs were 1-3 times that in blood and erythrocytes contained about twice the amount of benzene found in plasma. During inhalation exposure of rats to 1,000 ppm (2 hours per/day, for 12 weeks), benzene was stored longer (and eliminated more slowly) in female and male rats with higher body fat content than in leaner animals (Sato et al. 1975). 

Sato A, Nakajima T, Fujiwara Y, et al. 1975. Kinetic studies on sex differences in susceptibility to chronic benzene intoxication - with special reference to body fat content. Br J Ind Med 32 321-328. 

A cytokine, produced predominantly by fat cells (adipocytes) plasma levels of leptin rise and fall in parallel to body fat content (> fat > leptin). 

C. Garenc, et ah. The alpha2-adrenergic receptor gene and body fat content and distribution the HERITAGE family study. Mol. Med., 2002, 8, 88-94. 

The effect of caffeine on metabolic rate has been well documented. A significant increase of 2-12% in metabolic rate was observed with caffeine doses of 200-300 mg. It was concluded that EGCG and caffeine from the tea act synergistically to produce the thermogenic response and an increase in fat oxidation. It is clear that the consumption of oolong tea stimulates both EE and fat oxidation in normal-weight man. This raises the possibility that tea consumption could have some beneficial effect on an individual s ability to maintain a lower body fat content. ... 

Amenorrhea (lack of menses) usually develops during anorexia nervosa and other conditions when a woman s body fat content falls to approximately 22% of her total body weight. The immediate cause of amenorrhea is a reduced production of the gonadotropic protein hormones (luteinizing hormone and follicle-stimulating hormone) by the anterior pituitary the connection between this hormonal change and body fat content is not yet understood. 

Saundersoa C.L. Whitehead, C.C. (1987). N Methyl histidine excretion and [U- C] amino acid oxidation in fully fed chickens from two lines for high and low body fat contents. Comp. Biochem. Physiol, 86B, 419-22. 

Takada, R., Saitoh, M., and Mori, T. (1994) Dietary y-Linolenic Acid-Enriched Oil Reduces Body Fat Content and Induces Liver Enzyme Activities Relating to Fatty Acid P-Ox-idation in Rats, J. Nutr. 124,469-474. 

Acid Rapidly Reduces Body Fat Content in Mice Without Affecting Energy iMskt. Am.J.Physiol. 276 Rl 172-1179 (1999). 

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