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Biomedical subjects

R Weinshilboum

Publications and source records attributed to R Weinshilboum.

46 records · Page 3Linked to original sources
PubMed1976

Human serum dopamine beta-hydroxylase: correlation of enzymatic activity with immunoreactive protein in genetically defined samples.

An antibody against human adrenal dopamine beta-hydroxylase (DBH) was used to quantitate immunoreactive DBH protein in human serum by an immunoprecipitation technique. A significant correlation was found between DBH enzyme activity and immunoreactive DBH protein in randomly selected serum samples (r = 0.94; N = 38; p less than .001). Studies of sera from obligate heterozygotes and individuals homozygous for the allele responsible for very low serum DBH enzymatic activity were compatible with a genetically mediated decrease in the quantity of circulating DBH protein in these subjects.

Adrenal Glands↗
PubMed1972

Catecholamines.

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Adrenal Medulla↗
PubMed1971

Serum dopamine- -hydroxylase: decrease after chemical sympathectomy.

Dopamine-beta- hydroxylase is an enzyme that is localized to catecholamine-containing vesicles in sympathetic nerves and the adrenal medulla, and is also found in the serum. Treatment of rats with 6-hydroxydopamine, a drug which destroys sympathetic nerve terminals, leads to a decrease in serum dopamine-beta-hydroxylase activity. The decrease is not due to an effect on the adrenal medulla or to an increase in circulating inhibitor or inhibitors of enzyme. These data represent evidence that at least a portion of the circulating dopamine-beta-hydroxylase activity arises from sympathetic nerve terminals.

Adrenal Medulla↗
PubMed1971

Enhanced release of dopamine- -hydroxylase from sympathetic nerves by calcium and phenoxybenzamine and its reversal by prostaglandins.

Dopamine-beta-hydroxylase (EC 1.14.2.1), an enzyme localized in sympathetic synaptic vesicles, was released together with norepinephrine during in vitro stimulation of the hypogastric nerve that innervates the vas deferens of the guinea pig. Stimulation of the nerve in the presence of high concentrations of calcium (7.5 mM) or phenoxybenzamine caused a marked increase in the amounts of the enzyme and norepinephrine released into the bath. The augmentation of release of dopamine-beta-hydroxylase by 7.5 mM calcium or phenoxybenzamine was reversed by prostaglandin E(2). These findings suggest that the release of the sympathetic neurotransmitter, norepinephrine, occurs by a process of exocytosis in which the vesicular content of soluble dopamine-beta-hydroxylase is also released. The depolarization-induced exocytosis, which is stimulated by calcium, may be affected by prostaglandin E(2) or phenoxybenzamine through inhibition or enhancement of the actions of calcium in the release process.

Animals↗
PubMed1970

Neurally mediated increase in dopamine-beta-hydroxylase activity.

The development of a sensitive and specific enzymatic assay for dopamine-beta-hydroxylase has enabled us to measure the activity of this enzyme in several tissues where it has previously been measured. The administration of reserpine leads to an increase in dopamine-beta-hydroxylase activity in the rat adrenal, heart, salivary gland, and in sympathetic ganglia. The increase in the heart is preceded by a small but significant fall. We have confirmed the increase in tyrosine hydroxylase which follows the administration of reserpine and have found that the activity of phenylethanolamine-N-methyltransferase also increases after administration of this drug. The activities of two enzymes not involved in the synthesis of catecholamines, monoamine oxidase and lactate dehydrogenase, are not affected by reserpine treatment. The rise of dopamine-beta-hydroxylase activity in the sympathetic ganglia is blocked by surgical decentralization.

Adrenal Glands↗
PubMedDate not supplied

Foreign compound metabolism studies with human liver obtained as surgical waste. Relation to donor characteristics and effects of tissue storage.

An investigation has been conducted on the foreign compound-metabolizing activity of human liver collected fresh from surgery or at autopsy from cadavers 3 to 18 hr old, and the effects of low temperature storage on the foreign compound-metabolizing activity of fresh human liver. The enzyme activities studied were microsomal cytochrome P-450 content, biphenyl 4-hydroxylation, benzo-(a)pyrene metabolism, halothane reduction, and 4-hydroxybiphenyl UDP-glucuronosyl transferase, as well as cytosolic thiopurine methyltransferase, thermostable (TS) phenolsulfotransferase, thermolabile (TL) phenolsulfotransferase, and 5-fluorouracil dehydrogenase. Cadaver liver was a poor source of material for metabolism studies with the majority of the enzymes investigated. There was an 84% decrease in the yield of microsomal protein, a 64% decrease in cytochrome P-450 content per mg of microsomal protein, and a 36% decrease in the biphenyl 4-hydroxylase specific activity in human cadaver liver that was a few hours old. UDP-glucuronosyl transferase showed a 70% decrease, TS phenolsulfotransferase a 84% decrease, TL phenolsulfotransferase a 97% decrease, and thiopurine methyltransferase no significant change in specific activity. The loss of activity for many of these enzymes could be simulated by keeping fresh human liver at the temperature of the body after death. Surgical waste provided a good source of fresh, histologically normal, human liver for metabolism studies. Microsomal cytochrome P-450 content showed a significant increase with the age of the liver donor. Metabolism of benzo(a)pyrene to 3-hydroxybenzo(a)pyrene and benzo(a)pyrene-7,8- and -9,10-diols showed up to 136% higher rates in fresh liver microsomes from female donors.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗