Starvation, metabolism

Hunger-stein, m. salt-pan scale (sulfates of calcium and sodium, etc.), -stoffwechsel, m. starvation metabolism. -tod,w. (death from) starvation. 

During Fasting and Starvation, Metabolism Shifts to Provide Fuel for the Brain... 

Elia, M., Zed, C., Neale, C-, and Livesay, G. (1987). The energy cost of triglyceride fatty acid recycling in nonobese subjects after an overnight fast and four days starvation. Metabolism 36, 251-255. 

Van Riet, H., Schwartz, F., Kinderen, P. de Metabolic observations during the treatment of obese patients by periods of total starvation. Metabolism 13, 291-302 (1964)... 

Lowell, B.B., Ruderman, N.B., and Goodman, M.N., Regulation of myofibrillar protein degradation in rat skeletal muscle during brief and prolonged starvation. Metabolism, 35, 1121, 1986. 

The primary fate of acetyl CoA under normal metabolic conditions is degradation in the citric acid cycle to yield C02. When the body is stressed by prolonged starvation, however, acetyl CoA is converted into compounds called ketone bodies, which can be used by the brain as a temporary fuel. Fill in the missing information indicated by the four question marks in the following biochemical pathway for the synthesis of ketone bodies from acetyl CoA ... 

Hyperactivity of the orexin system, e.g. triggered by energy depletion, metabolic failure, hypoglycemia or hypoxia, in the context of starvation, sleep derivation, and stress, may predispose to addiction and... 

Complex metabolic processes carbon and amino acid starvation viral infection... 

A knowledge of normal metabohsm is essential for an understanding of abnormalities underlying disease. Normal metabolism includes adaptation to periods of starvation, exercise, pregnancy, and lactation. Abnormal metabolism may result from nutritional deficiency, enzyme deficiency, abnormal secretion of hormones, or the actions of drugs and toxins. An important example of a metabolic disease is diabetes mellitus. 

Figure 27-2. Relative changes in metabolic parameters during the onset of starvation.

Brain Coordination of the nervous system Glycolysis, amino acid metabolism Glucose, amino acid, ketone bodies (in starvation) Polyunsaturated fatty acids in neonate Lactate ... 

Once formed, collagen is relatively metabolically stable. However, its breakdown is increased during starvation and various inflammatory states. Excessive production of collagen occurs in a number of conditions, eg, hepatic cirrhosis. 

Feedback inhibition of amino acid transporters by amino acids synthesized by the cells might be responsible for the well known fact that blocking protein synthesis by cycloheximide in Saccharomyces cerevisiae inhibits the uptake of most amino acids [56]. Indeed, under these conditions, endogenous amino acids continue to accumulate. This situation, which precludes studying amino acid transport in yeast in the presence of inhibitors of protein synthesis, is very different from that observed in bacteria, where amino acid uptake is commonly measured in the presence of chloramphenicol in order to isolate the uptake process from further metabolism of accumulated substances. In yeast, when nitrogen starvation rather than cycloheximide is used to block protein synthesis, this leads to very high uptake activity. This fact supports the feedback inhibition interpretation of the observed cycloheximide effect. 

W. C. Plaxton, Metabolic aspects of phosphate starvation in plants. Phosphorus in Plant Biology Regulatory Roles in Molecular, Cellular, Organi.smic, and Eco.sy.s-lein Proces.ses (J. P. Lynch and J. Deikman eds.), American Society of Plant Physiologists, 1998, p. 229. 

The production of ligninolytic enzymes takes place during the secondary metabolism of several WRF. The lignin degrading system is induced when starvation of C or N occurs moreover, agitation and temperature can significantly affect the levels of these enzymes factors affecting LMEs are reviewed by Gao et al. [1]. 

Diabetes results from a lack of insulin secretion by the pancreas. Without insulin, cells take up glucose very slowly. The lack of insulin results in an inability to use blood glucose for fuel. Consequently, the body behaves as if it were starving even though food is available. The metabolic responses of the untreated insulin-dependent diabetic are essentially the metabolic responses of starvation. 

Glycogen stores in liver and kidney are exhausted in about 24 hours. After this, the body must find glucose equivalents somewhere. The major metabolic adaptations of starvation are the result of having to maintain glucose levels without any direct source of it (Fig. 17-8). 

The alanine cycle accomplishes the same thing as the Cori cycle, except with an add-on feature (Fig. 17-11). Under conditions under which muscle is degrading protein (fasting, starvation, exhaustion), muscle must get rid of excess carbon waste (lactate and pyruvate) but also nitrogen waste from the metabolism of amino acids. Muscle (and other tissues) removes amino groups from amino acids by transamination with a 2-keto acid such as pyruvate (oxaloacetate is the other common 2-keto acid). 

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