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Biomedical subjects

T M Smith

Publications and source records attributed to T M Smith.

At least 91 records · Page 5Linked to original sources
PubMed1982

Regulation of nitrogen catabolic enzymes in Bacillus spp.

The levels of the inducible nitrogen catabolic enzymes arginase (L-arginine amidinohydrolase, EC 3.5.3.1) and alanine dehydrogenase (L-alanine:NAD+ oxidoreductase [deaminating], EC 1.4.1.1) from Bacillus licheniformis and histidase (L-histidine ammonia-lyase, EC 4.3.1.3) from Bacillus subtilis and the ammonia assimilatory enzymes from B. licheniformis were determined in cultures grown in the presence of different nitrogen sources. Although the levels of these enzymes were dependent upon the nitrogen source present, induction of the catabolic enzymes in response to the addition of inducer occurred even in the presence of preferred nitrogen sources. Intracellular pool sizes of ammonia, glutamate, glutamine, and alpha-ketoglutarate were measured in continuous cultures of b. licheniformis growing in the presence of different nitrogen sources. A comparison of the pool sizes of these metabolites with the ammonia assimilatory enzyme levels showed that the pools of the metabolites did not change in a manner consistent with their use as regulators of the synthesis of any of these enzymes.

Alanine Dehydrogenase↗
PubMed1982

Specific approaches and techniques in the treatment of gay male alcohol abusers.

An extended discussion of specific therapeutic approaches and techniques with homosexual male alcohol abusers, including dealing with low self-esteem, sober sex, getting high, getting "far out" sexually, double lives, second rate relationships, social bonding, and aging. In this paper, the bias of treatment approaches is toward individualized, interpersonal, holistic eclecticism: a combination of responsibility building therapy, awareness therapy, medical and neurophysiological approaches, strategic therapy, utilization of altered states of consciousness, and attitudinal change therapy.

Adult↗
PubMed1980

Release of synaptosomal dopamine formed from tyrosine and L-DOPA.

The present report compares the synaptosomal release of [3H]dopamine, continuously forming from [3H]DOPA, with that of [14C]dopamine, forming from [14C]tyrosine as a marker of dopaminergic nerve endings. For the purpose of the comparison, synaptosomal (P2) preparations from rat caudate nuclei were incubated with L-[3H]DOPA and [14C]tyrosine for 10 min and the particulates were rapidly separated from the medium postincubation. The separated fractions were analyzed for the level of double labelled (14C/3H) dopamine and the synaptosomal content of the labelled substrates. Of the total labelled dopamine formed, the fraction that was present in the medium, following the synaptosomal release, was determined. Tested were the release enhancing effects of various additions which included several known dopaminergic agents, serotonin and 5-hydroxytryptophan. The data show that the addition of dopamine to the incubation mixture to either 0.5 or 1.0 muM concentration markedly enhanced the release of labelled dopamine. Serotonin when added to 5.0 muM concentration also raised the medium content of labelled dopamine but it was ineffective at 1.0 muM. 5-Hydroxytryptophan, 1.0 or 5.0 muM, had no effect. For the comparison of the release enhancing effects of an addition on [14C]dopamine and [3H]dopamine, the corresponding release indices (release index = medium/total ratio of labelled dopamine in the presence of an addition divided by the same ratio in control (no addition) sample) were determined. The data indicate that the index of [14C]dopamine did not differ significantly from that of [3H]dopamine following the addition of either dopamine, serotonin or 5-hydroxytryptophan at any of the concentrations tested. A similar lack of difference between the index of [14C]dopamine and that of [3H]dopamine was observed following the addition of reserpine (1.8 muM), although a considerable enhancement of labelled dopamine release occurred. The addition of either amphetamine (9.1 muM) or amfonelic acid (9.1 muM) also enhanced labelled dopamine release but in their presence the index of [3H]dopamine was significantly higher than that of [14C]dopamine. Amfonelic acid preferentially raised the [3H]dopamine index at the lowest concentration of 0.91 muM that we have tested and also after only 5 min of incubation; coaddition of reserpine increased the [14C]dopamine release, thus abolishing the preferential effect of amfonelic acid on [3H]dopamine release, thus abolishing the preferential effect of amfonelic acid on [3H]dopamine. When the incubation was performed without an addition (control sample), no difference (NS) was observed between the particulate to medium distribution of [14C]dopamine and that of [3H]dopamine after either 5, 10 or 15 min. The results suggest that (a) dopamine synaptosomally formed from L-DOPA may exist in a pool distinct from that dopamine arising from tyrosine hydroxylation and (b) the observed dopamine compartmentation may be due to some mechanism distinct from any possible participation of serotoninergic particles...

Animals↗
PubMed1979

Insulin secretory dynamics after two consecutive intravenous stimulations with glucose and/or tolbutamide.

Intravenous glucose and/or tolbutamide administered in two consecutive pulses 30 and 60 min apart to the same subjects using identical doses showed that insulin secretory responses was altered during a subsequent stimulation and that this was modulated by the time factor. Insulin response was more sustained after the second glucose pulses and the insulin peak response was delayed and diminished if the second glucose dose was given 30 min after the first, but not if given 60 min later. It is suggested that the beta-cell membrane might remain partially depolarized above a certain glucose level or that a postulated signal relay mechanism might become saturated. Responses to two tolbutamide pulses did not show these characteristics; however, the second insulin response was smaller than the first. When the first pulse was glucose and the second tolbutamide, or vice versa, the second responses were altogether different from those elicited by the double doses of either tolbutamide or glucose. To explain these characteristic patterns of insulin secretory dynamics, the existence of occult glucose receptors on the beta-cell that are opened up by tolbutamide was postulated. These studies do not support the two-pool theory, or at least restrict it to glucose-stimulated insulin response. The positive correlations between the first and the second insulin responses in all tests argue strongly against the existence of an insulin feedback mechanism in man.

Adult↗
PubMed1979

Synaptosomal dopamine from phenylalanine in brain: effects of some dopaminergic agents.

This report demonstrates for the first time that the synthesis and release responses to some dopaminergic agents may be elicited from that synaptosomal dopamine which may be formed by the hydroxylations of phenylalanine. Amphetamine and Cogentin increased the release of dopamine formed from 14C-phenylalanine in rat caudate nucleus synaptosomal preparation and concomitantly stimulated the synthesis. Amfonelic acid also caused a net release of that dopamine. Reserpine markedly increased the medium level of formed dopamine and at the same time inhibited the synthesis of the amine. Triton X-100 detergent almost completely inhibited the substrate uptake and the formation of dopamine. In conclusion, the results suggest that synaptosomal particles represent an unit capable of synthesizing dopamine from phenylalanine and that the synthesis from this precursor may be under the regulatory control of the particles to some degree.

Animals↗
PubMed1977

Dopamine formation from phenylalanine: independent existence in caudate nucleus synaptosomes.

Dopa and dopamine formations from phenylalanine and tyrosine in rat caudate nucleus synaptosomal preparation were studied. Phenylalanine and tyrosine, labelled with either 14C or 3H, were employed as cosubstrates leading to the formations of double labelled Dopa and dopamine. The ratio of the two isotopes in dopamine was found to be significantly different from that in Dopa. The results suggest that Dopa formed from the cosubstrates are compartmented.

Animals↗
PubMed1977

Tricarboxylic acid cycle enzyme activities in adult Schistosoma mansoni and Schistosoma japonicum.

Reduced tricarboxylic acid cycle enzyme activities were found in paired adult Schistosoma mansoni and S. japonicum in comparison to those reported for S. mansoni cercariae (Coles, 1973). Succinate dehydrogenase activity, which has not been previously reported for either adult blood fluke, is more than twice as great in paired adult S. japonicum as in paired adult S. mansoni, but the activity is low in both species of adult worms. The similar low levels of tricarboxylic acid cycle enzyme activities which occur in adult S. mansoni and S. japonicum further substantiate the fact that anaerobic glycolysis is the major energy source in adults of both species.

Animals↗
PubMed1977

Schistosoma mansoni and Schistosoma japonicum: comparison of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in adults.

Glucose-6-phosphate dehydrogenase activity in paired adult Schistosoma mansoni is about twice as great as in paired adult Schistosoma japonicum. 2. 6-phosphogluconate dehydrogenase activity accounts for 25.8% of the measured production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in S. japonicum but only 8.6% of the measured production of NADPH in S. mansoni. 3. These data suggest a species difference in 6-phosphogluconate metabolism.

Animals↗