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Biomedical subjects

B I Brown

Publications and source records attributed to B I Brown.

At least 37 records · Page 2Linked to original sources
PubMed1978

Structure of the polysaccharide formed by incubating glycogen with D-[14C]glucose in the presence of the glycogen debranching enzyme [amylo-(1 linked to 6)-glucosidase-4-alpha-glucanotransferase].

[14C]Glycogen has been synthetized in vitro by incubating D-[14C]glucose with rabbit-liver glycogen in the presence of a pure preparation of the glycogen debranching enzyme [amylo-(1 linked to 6)-glucosidase-4-alpha-glucanotransferase]. The course of the reaction has been monitored and 14C-products isolated after 30 min and 5 h. The distribution of D-[14C]glucose groups in the polysaccharides has been determined by debranching the molecules with a crystalline isoamylase from Pseudomonas. The quantities of unlabeled and 14C-linear unit chains containing D-[14C]glucose at their reducing ends have been determined by paper chromatography followed by enzymic degradation and analysis. In the 30-min product, between 65 and 85% of the D-[14C]glucose groups were covered by unlabeled groups because of transferase action. In the 5-h product, the extent of covering approached 100%. Extensive redistribution of unlabeled groups also was found to have occurred, even in the early stages of the reaction. It is concluded that the D-[14C]glucose incorporation assay for amylo-(1 linked to 6)-glucosidase, as ordinarily carried out, is probably not specific just for the hydrolytic action of this enzyme, but that it depends indirectly on its transferase activity as well.

Animals↗
PubMed1972

Hepatic fructose-1,6-diphosphatase deficiency. A cause of lactic acidosis and hypoglycemia in infancy.

An 8-month-old female, maintained on breast feeding for 6 months, experienced numerous attacks of hyperventilation when weaned to baby food and was admitted with severe lactic acidosis (20 mM) and hypoglycemia. Physical examination was negative except for hepatomegaly. Fasting (18 hr) after stabilization on a high carbohydrate diet resulted in hypoglycemia (plasma glucose 40 mg/100 ml), lactic acidosis (6-10 mM), and a rise in plasma alanine. Glucagon produced a glycemic response after 6 hr, but not after 18 hr fasting. Intravenous galactose increased plasma glucose (Delta 45 mg/100 ml) but intravenous fructose, glycerol, and alanine caused a 40-50% fall in plasma glucose and a significant rise in lactate (Delta 3-4 mM). Liver biopsy showed fatty infiltration. Liver slices incubated with galactose, lactate, fructose, alanine, or glycerol converted only galactose to glucose. Hepatic glycolytic intermediates were increased below the level of fructose-1,6-diphosphate and decreased above. Hepatic phosphorylase, glucose-6-phosphatase, amylo-1,6-glucosidase, phosphofructokinase, fructose-1-phosphate aldolase, and fructose-1,6-diphosphate aldolase levels were normal, but no fructose-1,6-diphosphatase (FDPase) activity was detected. Further studies on the liver homogenate of this patient revealed the presence of an acid-precipitable activator of FDPase. Normal plasma glucose and lactate levels were maintained on an 800 cal diet of 66% carbohydrate (sucrose and fructose excluded). 5% protein, and 20% fat. When carbohydrate was reduced to 35% and protein or fat increased to 23 and 53% respectively, lactic acidosis and hypoglycemia recurred. These studies show that a deficiency of FDPase produced infantile lactic acidosis and hypoglycemia and can be controlled by an appropriate diet.

Acidosis↗
PubMed1969

Pompe's disease: detection of heterozygotes by lymphocyte stimulation.

A technique has been developed for the detection of inborn errors by multiple enzyme analysis of lymphocytes stimulated by phytohemagglutinin. Its practicality has been demonstrated in Pompe's disease in which there is a deficiency of acid alpha-1,4-glucosidase (E.C.3.2.1.20).

Clinical Enzyme Tests↗