Adipose tissue absorptive state

Chloroform absorption depends on the concentration in inhaled air, the duration of exposure, the blood/air partition coefficient, the solubility in various tissues, and the state of physical activity which influences the ventilation rate and cardiac output. Pulmonary absorption of chloroform is also influenced by total body weight and total fat content, with uptake and storage in adipose tissue increasing with excess body weight and obesity. 

Unlike isotretinoin, acitretin (Soriatane) is not primarily sebosuppressive. Rather, it promotes normalization of dysregulated keratinocyte proliferative activity in the epidermis and is also antiinflammatory. Oral absorption is optimal when acitretin is taken with a fatty meal peak levels are reached approximately 3 hours after ingestion, while steady-state plasma levels are achieved after approximately 3 weeks of daily dosing. The mean terminal elimination half-life of the parent compound is 49 hours. However, when consumed with ethanol, acitretin may be transesterifled to form etretinate, a retinoid that is stored in adipose tissue, resulting in a much longer half-life (3-4 months or longer). 

Major metabolic pathways in adipose tissue in the absorptive state. [Note The numbers in the circles, which appear both on the figure and in the corresponding text, indicate important pathways for adipose tissue metabolism.]... 

Regarding human health risks the Deca risk assessors note that scientific information on bioconcentration in human adipose tissues and subsequent elimination via for example breast milk is insufficient, but that other brominated diphenyl ethers (i.e. Hexa, Penta and Tetra) are excreted with breast milk. Based on the low rate of oral absorption in rats and the low bioaccumulation potential, the Deca risk assessors state that they might anticipate a rather low excretion of this compound in the breast milk. ... 

Dimethyl ether is rapidly absorbed by the respiratory tracts with steady-state levels attained within 30 min. The material is cleared rapidly with the mean biological half-life being 90 min. Absorption was proportional to the dimethyl ether concentration breathed. No tissue storage, particularly in adipose tissue, was seen. 

FA stored within the TAG of adipose ceUs constitute the vast majority of energy reserves in animals. While the TAG pool in adipocytes provides a reservoir of energy for times of prolonged restricted caloric intake, there is also a normal acute flux of FA into and out of adipose tissue in response to meals and other factors, such as insuhn [8, 9J. TAG hydrolysis in adipocytes, termed hpolysis, contributes to the increased levels of plasma NEFA by two mechanisms, one direct and the other indirect. In the post-absorptive state or during starvation FA are normally released from adipocytes directly into the plasma and transported to various tissues where they serve as a source of energy. In the insulin-resistant state this direct release of FA is exacerbated, because the reduction in the anti-lipolytic action of insuhn (see below) leads to increased hpolysis and a consequent increase in the release of FA from adipocytes into plasma. In contrast to the postabsorptive direct FA release, there is... 

Ingestion, absorption and deposition of fat into adipose tissue is considerably high (i.e. 60-100 g/day). In the post-absorptive state, 50-90% of the body s total energy needs, including that of the heart, is met by free fatty acids delivered from adipose tissue. The total movement of fatty acids from one tissue to the other is voluminous and fast, while that of cholesterol and phos-phohpids is less and rather slow. The daily turnover of cholesterol, representing the transfer from the catabohc to the anabolic sites within the body, approximates 1 g. More than 90% of the cholesterol leaves the body in the feces as bile acids and predominantly as cholic acid. 

In the post-absorptive state stored fat is presented to the tissues in four forms free fatty acids derived directly from adipose tissue triglycerides formed in the liver from fatty acids and acetoacetate and hydroxybutyrate formed by the partial oxidation of free fatty acids. Free fatty acids and ketone bodies are readily oxidizable. It may be that more than one form is necessary because free fatty acids alone, owing to their low solubility and their relative toxicity, cannot be transported in sufficient quantities to meet the fuel requirements of some tissues, such as heart muscle. The other possibility for the existence of multiple forms of this substrate is that it allows direction of particular fuels to specific organs. 

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