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Biomedical subjects

R Young

Publications and source records attributed to R Young.

At least 307 records · Page 17Linked to original sources
PubMed1981

The home visit in the multidisciplinary teaching of primary care physicians.

Evaluating a person's physical and psychological make-up and his physical and cultural environment are skills that must be learned by physicians-in-training. The faculty of the Boston City Hospital Primary Care Training Program at the East Boston Neighborhood Health Center uses the home visit to help residents develop these skills. This article discusses the home visit program and its impact on residents, their patients, and the faculty.

Boston↗
PubMed1981

Galactosaemia: a new severe variant due to uridine diphosphate galactose-4-epimerase deficiency.

A baby presented on day 5 with symptoms of classical galactosaemia which are believed to be owing to a lack of uridine diphosphate-4-epimerase, rather than to the usual galactose-1-phosphate uridyl transferase defect. Apart from galactosaemia the condition was characterised biochemically by a red cell accumulation of galactose-1-phosphate and uridine diphosphate galactose. Galactose restriction modified the acute clinical and biochemical abnormality, but it appears essential to include some galactose in the diet in this condition to allow synthesis of galactosides, including the brain gangliosides.

Carbohydrate Epimerases↗
PubMed1981

Metabolic alpha-hydroxylation of N-nitrosomorpholine and 3,3,5,5-tetradeutero-N-nitrosomorpholine in the F344 rat.

We studied the metabolism in the male F344 rats of N-nitrosomorpholine and of 3,3,5,5-tetradeutero-N-nitrosomorpholine ; the latter is less carcinogenic and less mutagenic than is N-nitrosomorpholine. alpha-Hydroxylation (3- or 5-hydroxylation) of N-nitrosomorpholine by liver microsomes and a reduced nicotinamide adenine dinucleotide phosphate-generating system produced (2-hydroxyethoxy)acetaldehyde, which was identified as its 2,4-dinitrophenylhydrazone derivative. When we administered N-nitrosomorpholine to rats i.p., we did not detect (2-hydroxyethoxy)acetaldehyde in the urine, but we did identify (2-hydroxyethoxy)acetic acid (16% of the dose). We also identified N-nitroso(2-hydroxyethyl)glycine (33% of the dose) from beta-hydroxylation (2- or 6-hydroxylation), N-nitrosodiethanolamine (12%), and unchanged N-nitrosomorpholine (1.5%) in the urine. The deuterated analogs of the above metabolites were isolated from the urine of rats treated with 3,3,5,5-tetradeutero-N-nitrosomorpholine in yields as follows: (2-hydroxyethoxy)acetic acid (3.4%); N-nitroso(2-hydroxyethyl)glycine (37%); N-nitrosodiethanolamine (12%); N-nitrosomorpholine (0.4%). These data demonstrates that deuterium substitution in the alpha-positions of N-nitrosomorpholine caused a decrease in the extent of alpha-hydroxylation and indicate that alpha-hydroxylation is the mechanism of activation of N-nitrosomorpholine.

Animals↗
PubMed1980

Hallucinogenic agents as discriminative stimuli: a correlation with serotonin receptor affinities.

A choice between two levers in an operant chamber was used to train 24 rats, under a variable-interval 15 s schedule of sweetened milk reinforcement, to discriminate a hallucinogenic (psychotomimetic) agent, 5-methoxy-N,N-dimethyltryptamine (5-OMe DMT), from saline administration. The 5-OMe DMT stimulus generalized in a dose-related manner to each of 14 tryptamine related analogs. With the exception of one compound, the effective dose for the 5-OMe DMT response correlated highly (r = -0.86) with 5-HT receptor affinity (as determined using an isolated rat fundus preparation).

Animals↗
PubMed1980

Double-blind comparison of ketazolam, diazepam and placebo in once-a-day vs t.i.d. dosing.

Comparison of ketazolam given once-a-day with diazepam given three times a day and placebo given either once or 3 times a day in 101 anxious outpatients showed ketazolam to be significantly better than placebo in alleviating the symptoms of anxiety and, on several measures of efficacy, better than diazepam as well. Significantly fewer patients on ketazolam dropped out of the study due to ineffective medication than on the other 3 treatments. The incidence of side effects was lowest in the ketazolam group. Of particular note, drowsiness was reported twice as often by diazepam patients as by ketazolam patients.

Adolescent↗
PubMed1980

Metabolism of the tobacco specific nitrosamines, N'-nitrosonornicotine and 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone.

The metabolism, in the F-344 rat, of the tobacco-specific carcinogens, N'-nitrosonornicotine (NNN) and 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was studied. NNN was hydroxylated at each position of the pyrrolidine ring; 2'-hydroxylation gave 4-hydroxy-1-(3-pyridyl)-1-butanone in vitro and the corresponding acid in vivo, 3'-hydroxylation gave 3'-hydroxyNNN, 4'-hydroxylation gave 4'-hydroxy-NNN and 5'-hydroxylation gave 4-hydroxy-4-(3-pyridyl)butanal (in vitro) and 4-hydroxy-4-(3-pyridyl) butanoic acid (in vivo). The principle ring hydroxylation in the untreated F-344 rat was 5'-hydroxylation. Pyridine N-oxidation was also observed, giving NNN-1-N-oxide as a major metabolite. The principle urinary metabolites of NNN were formed by 5'-hydroxylation and pyridine-N-oxidation. For NNK, a major process was reduction of the carbonyl to give 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanol. alpha-Hydroxylation of both the N-methyl and N-methylene groups was also observed, as was formation of NNK-N-oxide in vitro and in vivo.

Animals↗
PubMed1980

Metabolism in the F344 rat of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone, a tobacco-specific carcinogen.

The metabolism of the tobacco-specific carcinogen, 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), was studied in the F344 rat, in which it induces tumors of the nasal cavity, liver, and lung. When NNK was incubated with rat liver microsomes and a reduced nicotinamide adenine dinucleotide phosphate-generating system, metabolites resulting from alpha-hydroxylation, carbonyl reduction, and N-oxidation were isolated. alpha-Hydroxylation at the methylene carbon gave 4-oxo-4-(3-pyridyl)butanal, whereas alpha-hydroxylation at the methyl carbon gave myosmine and 4-hydroxyl-1-(3-pyridyl)butan-1-one. The formation of these products involved the intermediacy of electrophilic diazohydroxides or carbonium ions which may be proximate or ultimate carcinogens of NNK. Carbonyl reduction gave 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)butan-1-ol and N-oxidation yielded 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone. When rats were gavaged with NNK, the microsomal products of alpha-hydroxylation were not detected in the 48-hr urine. Compounds which presumably resulted from further oxidation or reduction of these products, 4-oxo-4-(3-pyridyl)butyric acid, 4-hydroxy-4-(3-pyridyl)butyric acid, and 4-hydroxy-1-(3-pyridyl)butan-1-ol, were isolated. 4-(N-Methyl-N-nitrosamino)-1-(3-pyridyl)butan-1-ol and 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl-N-oxide)-1 butanone were also urinary metabolites.

Animals↗