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Biomedical subjects

G Briggs

Publications and source records attributed to G Briggs.

9 recordsLinked to original sources
PubMed1992

Season of birth of schizophrenics in Mississippi, USA.

Prior reviews indicate that schizophrenics tend to be born in the winter, relative to non-psychiatric controls. This conclusion has been criticized, however, as the association between birth seasonality and schizophrenia may be the result of a statistical artifact, the age-incidence effect. To examine this possibility, we studied the birth seasonality of 2892 schizophrenics, controlling for the age-incidence effect. Both before and after instituting these controls, we found excesses for the months of December and March. We conclude that the age-incidence hypothesis does not provide any general explanation of the season-of-birth effect in schizophrenia.

Adolescent↗
PubMed1991

An inducible gene expression system for Neurospora crassa.

Neurospora crassa acetyl CoA synthetase is highly induced when the growing mycelium is transferred from sucrose- to acetate-based medium. The inducible promoter of this gene has been isolated and used to control the expression of glutamate dehydrogenase. Transformants containing this expression cassette show gdh levels up to 25 times higher than the nontransformed host strain. This expression cassette will form the basis of a system of heterologous gene expression.

Acetate-CoA Ligase↗
PubMed1991

Differences between schizophrenics born in winter and summer.

A total of 1814 patients were studied from the Mississippi State Hospital with a DSM-III diagnosis of schizophrenia and aged 15-39 years at the time of admission. The 634 schizophrenics with a birth date between 1 December and 31 March were compared with the 1180 born between 1 April and 30 November for age of admission, race, sex, marital status, duration of initial admission and clinical subtype. The only significant difference between the variables was the duration of the first admission: winter-born patients had a shorter psychiatric hospitalization than summer-born schizophrenics. These findings are discussed in accord with similar studies.

Adolescent↗
PubMed1982

Mutagenicity of substituted carbazoles in Salmonella typhimurium.

Mutagenic activities of 1-, 2-, 3-, 4-, and 9-methylcarbazole were evaluated in S. typhimurium TA1535, TA1537, TA1538, TA98, and TA100. Only 9-methylcarbazole was found to be mutagenic in S. typhimurium TA100 in the presence of rat-liver homogenate. Mutagenic activity was also observed in TA100 for 2,9-, 3,9-, and 4,9-dimethylcarbazole. None of these methylated carbazole derivatives was mutagenic in TA1535, TA1537, TA1538 and TA98 in either the presence of absence of rat-liver homogenate. These results indicate that a 9-methyl substituent is associated with the mutagenic activity of these carbazole derivatives. Comparative studies on the mutagenic activity of 9-substituted carbazoles demonstrated that the activity of 9-ethylcarbazole was less than that of 9-methylcarbazole. 9-Phenyl- and 9-i-propylcarbazole were inactive under identical assay conditions. 9-Hydroxymethylcarbazole, a major metabolite of 9-methylcarbazole, was confirmed to be a direct-acting mutagen in S. typhimurium TA100. 9-Formylcarbazole was inactive as a mutagen when assayed with or without metabolic activation. These data are consistent with the finding that 9-hydroxymethylcarbazole is a major proximate mutagenic form of 9-methylcarbazole.

Animals↗
PubMed1981

Mutagenicity of aminocarbazoles and nitrocarbazoles.

The mutagenic activity of all 4 isomeric aminocarbazoles and 4 nitrocarbazoles was evaluated in Salmonella typhimurium tester strains TA98. TA100 and TA1535. All compounds were assayed both in the presence and absence of liver homogenate from Aroclor-treated rats. Among the aminocarbazoles, 2-aminocarbazole was found to be most active in both tester strains, although somewhat less active than 2-aminofluorene. 3-Aminocarbazole was the only other isomer that was mutagenic towards TA98 at the dose levels employed (5--200 micrograms). 4-Aminocarbazole was moderately active in TA100, and 1-aminocarbazole was inactive in both TA98 and TA100. Similar differences in mutagenic potency and specificity towards the tester strains were observed for the related series of nitrocarbazoles.

Amines↗