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Biomedical subjects

N H Neff

Publications and source records attributed to N H Neff.

At least 163 records · Page 9Linked to original sources
PubMed1978

Studies on the control of pineal indole synthesis: cyclic nucleotides, adenylate cyclase and phosphodiesterase.

An overview of the biochemical events that occur when postsynaptic pineal beta-adrenergic receptors are stimulated is presented. Emphasis is placed on the importance of the adenylate cyclase system for the induction of N-acetyltransferase (NAT). Super- and subsensitive responses of NAT to receptor agonists are related to cAMP concentration, adenylate cyclase and phosphodiesterase activities and receptor binding sites.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1977

The dynamics of dopamine metabolism in various regions of rat brain.

Dopamine metabolism was studied in various regions of rat brain by following the decline of 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxyphenylacetic acid (HVA) from brain after treatment with pargyline, or from the accumulation of the acids after treatment with probenecid. The decline of DOPAC and HVA after pargyline treatment appeared exponential in all regions of brain studied with half-lives of about 13 min for HVA and 6.5 min for DOPAC. DOPAC was the major metabolite of dopamine, with various brain regions producing between 2-5 times more DOPAC than HVA. HVA accumulated after treatment with probenecid but the accumulation in 1 h did ot account for all of the HVA apparently eliminated from brain. DOPAC accumulated in some regions of brain (medulla, hypothalamus and midbrain) and not in others (cerebellum, cortex, striatum and hippocampus) after probenecid treatment. We conclude that dopamine metabolism is not uniform in brain and that the accumulation of DOPAC and HVA in brain after probenecid treatment only accounts for a minor fraction of the dopamine formed in brain.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1977

Differential distribution of type A and B monoamine oxidase in neuronal tissues.

Various neuronal tissues of the albino rabbit were assayed for type A and type B monoamine oxidase, using norepinephrine and 2-phenylethylamine as substrates, respectively. There was an apparent positive correlation between the sympathetic character of peripheral nerves and the presence of type A monoamine oxidase activity. Type A enzyme activity was 15 fold higher in the superior cervical ganglion than in the vagus nerve. Type B activity was more uniformly distributed.

Animals↗
PubMed1977

Activation of the nigrostriatal dopaminergic pathway by injection of cholera enterotoxin into the substantia nigra.

Twenty-four hours after unilateral injection of cholera enterotoxin into the rat substantia nigra there is an increase, in the striatum on the injected side, of basal adenylate cyclase activity, 3,4-dihydroxyphenylacetic acid, and 3-methoxy-4-hydroxyphenylacetic acid. Moreover, there is an increase of motor activity, and rats tend to circle contralateral to the side of the injection. Injection of cholera enterotoxin into brain nuclei may be a useful procedure for pharmacologically activating selected neuronal systems of brain and for studying the pharmacology of drugs that are suspected of interacting with these systems.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1977

Transfer of ADP-ribose from NAD to choleragen: a subunit acts as catalyst and acceptor protein.

Choleragen selectively incorporates 3H from [3H]NAD labeled on the adenosine moiety and not 14C from [14C]NAD labeled on the nicotinamide moiety. This reaction does not require protein in addition to choleragen. Incorporation of isotope does not proceed at 4 degrees, requires dithiothreitol, is stable after extensive washing with cold trichloroacetic acid, and is decreased 80% by boiling in trichloroacetic acid. Studies with the A and B subunits of choleragen show that the A subunit catalyzes ADP-ribosylation and serves as an acceptor protein. The B subunit does not show catalytic or acceptor activity. We conclude that choleragen and its A subunit catalyze the hydrolysis of NAD and the enzymatic transfer of ADP-ribose to the A subunit.

Adenosine Diphosphate Sugars↗