Enzyme replacement in Fabry's disease, an inborn error of metabolism

Two patients with Fabry's disease were infused with normal plasma to provide active enzyme (ceramide trihexosidase) for hydrolysis of the plasma substrate, galactosylgalactosylglucosylceramide. Maximum ceramide trihexosidase activity occurred 6 hours after infusion of the plasma, attaining a level approximately 150 percent of that in normal plasma; enzymatic activity was detectable for 7 days. The amount of accumulated substrate in the plasma of these recipients decreased about 50 percent on day 10 after infusion. Thus, periodic replacement of ceramide trihexosidase activity in the plasma of patients with Fabry's disease might lead to consistently lower amounts of substrate in the plasma and a decrease in its rate of accumulation in tissues.     

Methylmalonate excretion in vitamin B12 deficiency

Urinary methylmalonate excretion is increased in rats with an insufficiency of vitamin B(12). Excretion of methylmalonate is not affected by folic acid, vitamin E, or selenium, but is markedly decreased by small amounts of vitamin B(12) added to the diet.     

Detection of inborn errors of metabolism: galactosemia

Radioautography of cultured, human, galactosemic and nongalactosemic cells shows that, in the presence of 0.05M D-galactono-gamma-lactone, the former incorporate much less galactose in acid-insoluble form than the latter. Presumably the lactone inhibits incorporation of the labeled galactose into pathways which do not require galactose-1-phosphate uridylyltransferase activity. Definite differences between the galactosemic and nongalactosemic condition can be demonstrated with as few as 100 to 1000 cells. This approach may be useful in facilitating prenatal detection of several kinds of inborn errors of metabolism.     

Methylmalonic aciduria: metabolic block localization and vitamin B 12 dependency

Methylmalonic aciduria is an inborn error of metabolism characterized by neonatal or infantile ketoacidosis. Leukocytes isolated from the peripheral blood of a 1-year-old child with this disorder converted negligible quantities of propionate-3-C(14) to carbon dioxide, but oxidized succinate-1,4-C(14) normally, an indication of a block in the conversion of propionate to succinate. Parenteral administration of vitamin B(18) resulted in a reduction in methylmalonic acid excretion and an increase in propionate oxidation by leukocytes in vitro. The results suggest a mutation of methylmalonyl-CoA isomerase, a vitamin B(12), dependent enzyme which converts methylmalonyl-CoA to succinyl-CoA, and provide the first demonstration of vitamin B(12) "dependency" in man.     

Enzyme release from polymorphonuclear leukocyte lysosomes: regulation by autonomic drugs and cyclic nucleotides

Osmotic release of beta-glucuronidase from polymorphonuclear leukocyte lysosomes is inhibited by catecholamines and adenosine 3',5'-monophosphate, and accelerated by cholinergic agents and guanosine 3',5'-monophosphate. These actions are specific for the sympathetic and parasympathetic neurotransmitters and for the two cyclic nucleotides, as phenylephrine, tyramine, choline, adenosine 5'-monophosphate and guanosine 5'-monophosphate do not inodify lysosomal enzyme release.     

Gyrate atrophy of the retina: inborn error of L-ornithin:2-oxoacid aminotransferase

Cultured fibroblasts from a patient with gyrate atrophy of the retina do not convert L-ornithine, uniformly labeled with carbon-14, to proline. This metabolic block is caused by deficient L-ornithine:2-oxoacid aminotransferase activity in the patient. Her heterozygote father has intermediate activity of this enzyme.     

维生素B12添加剂测定方法之比较分析

维生素B12粉剂是饲料生产中常用的维生素B12添加剂.本品是以维生素B12为原料,加入玉米淀粉或碳酸氢钙等稀释剂制成的粉剂,常见的3种产品分别含有1%、5%、10%维生素B12.维生素B12又称氰钴胺,因其含有元素钴,其粉剂为浅红色至棕色粉末,市售1%粉剂为浅红色,因其价格较高,该原料常有掺假现象.     

Chemical methylation of inorganic mercury with methylcobalamin, a vitamin B12 analog

Chemical methylation of mercuric chloride with methylcobalamin has been studied. Methylated mercury was detected by gas chromatography; and analysis of the products of the reaction by thin-layer chromatography revealed that the methylation proceeded at a remarkably high rate when methylcobalamin and inorganic mercury were mixed. Dimethylmercury was an initial product of the reaction.     

Zinc: a trace element essential in vitamin A metabolism

Zinc is necessary to maintain normal concentrations of vitamin A in plasma. By using animals deficient in both zinc and vitamin A, it was demonstrated that zinc is necessary for normal mobilization of vitamin A from the liver. These results suggest that cases of depressed vitamin A in plasma, unresponsive to vitamin A therapy, may respond to zinc supplementation.     

UASB—A/O工艺处理淀粉、淀粉制糖、VB_(12)混合废水

采用UASB—A/O工艺处理淀粉、淀粉制糖、VB12混合废水的实际运行结果表明,系统运行稳定,对COD、NH3-N的去除率分别为98.2%和92%,出水水质达到了《城镇污水处理厂污染物排放标准》(GB18918-2002)中的二级标准值。     

RNA metabolism in tracheal epithelium: alteration in hamsters deficient in vitamin A

The electrophoretic pattern of RNA molecules that are synthesized in vitro in tracheal epithelium from hamsters deficient in vitamin A differs from that of RNA synthesized in normal, pair-fed control hamsters. There is less RNA of low electrophoretic mobility in the epithelial cells deficient in vitamin A. This alteration is reversed after the deficient animals have been treated with vitamin A.     

A key enzyme in the biogenesis of lysosomes is a protease that regulates cholesterol metabolism

Mucolipidosis II is a severe lysosomal storage disorder caused by defects in the α and β subunits of the hexameric N-acetylglucosamine-1-phosphotransferase complex essential for the formation of the mannose 6-phosphate targeting signal on lysosomal enzymes. Cleavage of the membrane-bound α/β-subunit precursor by an unknown protease is required for catalytic activity. Here we found that the α/β-subunit precursor is cleaved by the site-1 protease (S1P) that activates sterol regulatory element-binding proteins in response to cholesterol deprivation. S1P-deficient cells failed to activate the α/β-subunit precursor and exhibited a mucolipidosis II-like phenotype. Thus, S1P functions in the biogenesis of lysosomes, and lipid-independent phenotypes of S1P deficiency may be caused by lysosomal dysfunction.