Acidity diseases linked

These three schemes of metabolism offer a unique perspective for discussing the analysis of metabolites in clinical chemistry labs. Traditionally, many laboratories have utilized the one analyte, one disease approach to testing. Hence, metabolite A in each of the scenarios would be a single measurement made in a laboratory, often by a relatively nonspecific test such as an immunoassay or fluorometric analysis. There are often numerous circumstances that can produce an elevation of a particular metabolite in addition to an enzyme deficiency produced by a metabolic disease. The result is a false positive. Measurement of more than one metabolite that is affected by a particular enzyme, Phe and Tyr as in the case of phenylketonuria (PKU), reduces the likelihood of a false positive as these amino acids are linked met-abolically. The case is similar in scenarios 2 and 3 where the pattern of metabolites may indicate one or more disorders that share common metabolic pathways. One final point regards scenario 2. Measurements of metabolites 2 or more steps away from the primary metabolic block, theoretically and in practice, are somewhat less reliable indicators of disease than the primary substrate. Often, however, no alternative is presented due to the primary substrate being chemically unstable or difficult to measure analytically. Generally, these metabolites are easier to detect in older infants as they accumulate over time. 

Diarrhea is a common problem that is usually self-limiting and of short duration. Increased accumulations of small intestinal and colonic contents are known to be responsible for producing diarrhea. The former may be caused by increased intestinal secretion which may be enterotoxin-induced, eg, cholera and E. col] or hormone and dmg-induced, eg, caffeine, prostaglandins, and laxatives decreased intestinal absorption because of decreased mucosal surface area, mucosal disease, eg, tropical spme, or osmotic deficiency, eg, disaccharidase or lactase deficiency and rapid transit of contents. An increased accumulation of colonic content may be linked to increased colonic secretion owing to hydroxy fatty acid or bile acids, and exudation, eg, inflammatory bowel disease or amebiasis decreased colonic absorption caused by decreased surface area, mucosal disease, and osmotic factors and rapid transit, eg, irritable bowel syndrome. 

Homocysteine arises from dietary methionine. High levels of homocysteiae (hyperhomocysteinemia) are a risk factor for occlusive vascular diseases including atherosclerosis and thrombosis (81—84). In a controlled study, semm folate concentrations of <9.2 nmol/L were linked with elevated levels of plasma homocysteiae. Elevated homocysteine levels have beea associated also with ischemic stroke (9). The mechanism by which high levels of homocysteine produce vascular damage are, as of yet, aot completely uaderstood. lateractioa of homocysteiae with platelets or eadothehal cells has beea proposed as a possible mechanism. Clinically, homocysteine levels can be lowered by administration of vitamin B, vitamin B 2> foHc acid. 

In addition to the twenty amino acids commonly found in proteins, two others—selenocysteine and pyrrolysine—are found in some organisms, and more than 700 nonprotein amino acids are also found in nature. y-Amino-butyric acid (GABA), for instance, is found in the brain and acts as a neurotransmitter homocysteine is found in blood and is linked to coronary heart disease and thyroxine is found in the thyroid gland, where it acts as a hormone. 

Increased awareness by consumers of the link between an increased intake of omega-3 fatty acids and a reduction in the risk of cardiovascular disease, has led to an increased demand for products with a higher content of these... 

Anaemia often becomes a characteristic feature of several chronic diseases, such as rheumatoid arthritis. In most instances this can be linked to lower than normal endogenous serum EPO levels (although in some cases a deficiency of iron or folic acid can also represent a contributory factor). Several small clinical trials have confirmed that administration of EPO increases haematocrit and serum haemoglobin levels in patients suffering from rheumatoid arthritis. A satisfactory response in some patients, however, required a high-dose therapy that could render this therapeutic approach unattractive from a cost benefit perspective. 

Primary lysosomal hydrolase defects. Two-thirds of the lysosomal storage diseases involve defects in genes that code for acid hydrolases. Table 41-2 lists 29 defects that have been defined so far. They have an autosomal recessive mode of inheritance, except for Hunter s syndrome and Fabry s disease, where the mode is X-linked recessive. The defective genes have been identified and mutations have been defined for nearly all. The nervous system is involved in most. Many of the disorders show a wide range of clinical severity, which may range from death in early childhood to a moderate disability in adulthood. 

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