Enzymes disorders

Renal carcinoma Multiple sclerosis Hepatitis vaccine Growth disorders Heart attack Enzyme disorder Cystic fibrosis... 

There are a number of enzyme disorders that cause plasma tHcy elevation (8-12) the two most important are discussed later. 

Deaths have occurred after the use of valproate in patients with ornithine transcarbamylase deficiency (SED-12, 133) (36) (SED-13, 149) (37). Additional evidence points to a need for caution in patients with any enzyme disorder. 

Antenatal diagnosis for fetuses at risk for the urea cycle enzyme disorders can be made by appropriate enzyme assays and DNA analysis in the cultured amniocytes. 

Because many enzyme systems are needed to complete the complex cholesterol-to-cortisol pathway, enzyme deficiencies may lead to disruptions of the normal cascade of events (see Fig. 74—2). This group of enzyme disorders is known as congenital adrenal hyperplasia, mainly because of the resultant chronic adrenal gland stimulation that occurs following enzyme deficiency. The most frequent is steroid 21-hydroxylase deficiency, accounting for more than 90% of cases. Any enzyme deficiency is capable of affecting any one or all three of the steroid pathways. Therefore treatment should be focused on replacement of the deficient hormone, as well as cessation of the chronic stimulation causing the hyperplasia. In Table 74—8, six of the most common enzyme deficiencies are briefly outlined. 

Major Applications Semicondnctors,i3 magnetic recording materials, nonlinear optical materials, photography, 16 determination of lysosomal enzyme disorders, antimiCTobial agent, anticancer agenti5... 

ENZYME COFACTORS OXIDATION/REDUCTION REACTIONS ENZYME DISORDERS G6PD DEFICIENCY FED, FASTING AND STARVATION STATES (i) 70... 

G6PD deficiency (17a) is the most common erythrocyte enzyme disorder in the world, affecting more than 100 million people worldwide. This generic conchrion is very common in the populations of East and Central Africa, the areas round the Mediterranean, the Middle East and South East Asia. The conchrion is inherited in an X-hnked manner, and female carriers have some protection against infection by malaria. 

Phenylpyruvic acid can cause mental retardation m infants who are deficient m the enzymes necessary to convert l phenylalanine to l tyrosine This disorder is called phenylketonuria, or PKU disease PKU disease can be detected by a simple test rou tmely administered to newborns It cannot be cured but is controlled by restricting the dietary intake of l phenylalanine In practice this means avoiding foods such as meat that are rich m l phenylalanine... 

CCK is found in the digestive tract and the central and peripheral nervous systems. In the brain, CCK coexists with DA. In the peripheral nervous system, the two principal physiological actions of CCK are stimulation of gaU. bladder contraction and pancreatic enzyme secretion. CCK also stimulates glucose and amino acid transport, protein and DNA synthesis, and pancreatic hormone secretion. In the CNS, CCK induces hypothermia, analgesia, hyperglycemia, stimulation of pituitary hormone release, and a decrease in exploratory behavior. The CCK family of neuropeptides has been impHcated in anxiety and panic disorders, psychoses, satiety, and gastric acid and pancreatic enzyme secretions. 

L-Asparaginase is used for the treatment of appropriate lymphoproliferative disorders in two clinical trials, L-asparaginase was used in combination with chemotherapy for the treatment of refractory acute nonlymphocytic leukemia in children (24) and adults (25). A moderate efficacy, attributable to the enzyme, was demonstrated in both trials. 

Another class of therapeutic agents is used for the treatment of certain genetic diseases or other enzymatic disorders caused by the dysfunction or absence of one particular enzyme. This often leads to an unwanted accumulation or imbalance of metaboUtes in the organism. Eor example, some anticonvulsive agents are inhibitors for y-aminobutyric acid aminotransferase [9037-67-6]. An imbalance of two neurotransmitters, glutamate and y-aminobutyric acid, is responsible for the symptoms. Inhibition of the enzyme leads to an increase of its substrate y-aminobutyric acid, decreasing the imbalance and subsequently relieving the symptoms of the disease. 

A much more common metabolic disorder, lactose intolerance, occurs commonly in most parts of the world (notable exceptions being some parts of Africa and northern Europe). Lactose intolerance is an inability to digest lactose because of the absence of the enzyme lactase in the intestines of adults. The symptoms of this disorder, which include diarrhea and general discomfort, can be relieved by eliminating milk from the diet. 

Organoselenium compounds in particular, once ingested, are slowly released over prolonged periods and result in foul-smelling breath and perspiration. The element is also highly toxic towards grazing sheep, cattle and other animals, and, at concentrations above about 5 ppm, causes severe disorders. Despite this, Se was found (in 1957) to play an essential dietary role in animals and also in humans — it is required in the formation of the enzyme glutathione peroxidase which is involved in fat metabolism. It has also been found that the Incidence of kwashiorkor (severe protein malnutrition) in children is associated with inadequate uptake of Se, and it may well be involved in protection... 

Thromboxane A-2 has been implicated in a number of disorders of the circulatory system including coronary artery spasms, unstable angina pectoris, traumatic and endotoxic shock, and heart attacks. It is formed normally very near its receptors and is rapidly deactivated by metabolizing enzymes so circulating levels are quite low. Furthermore, it is opposed in its actions by the prostacyclins. When these controls are defective, pathology results and drugs can be the resort in attempts to restore the normal healthy balance. For one example, furegrelate (6) is a throm-... 

Zinc and cadmium have an oxidation number of +2 in all their compounds. Zinc is an essential element for human health. It is present in many enzymes and plays a role in the expression of DNA and in growth. Zinc is toxic only in very-high amounts. However, cadmium is a deadly poison that disrupts metabolism by-substituting for other essential metals in the body such as zinc and calcium, leading to soft bones and to kidney and lung disorders. 

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