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Biomedical subjects

J David

Publications and source records attributed to J David.

At least 163 records · Page 9Linked to original sources
PubMed1977

Adaptive response due to changes in gene regulation: a study with Drosophila.

In spite of the critical role of the process of adaptation in evolution, there are few detailed studies of the genotypic and molecular basis of the process. Drosophila melanogaster flies selected for increased tolerance to ethanol exhibited higher levels of alcohol dehydrogenase (alcohol:NAD+ oxidoreductase; EC 1.1.1.1) activity than unselected controls. A series of tests (electrophoresis, product inhibition, temperature stability, pH optima, substrate specificity, and Michaelis constants) gave no evidence of structural differences in the enzyme of the selected and the control flies. However, quantitative immunological assays showed that the selected flies contained significantly higher amounts of alcohol dehydrogenase. Adaptation of the selected flies to higher alcohol tolerance has most likely taken place by changes not in the structural gene locus coding for the enzyme, but by regulatory changes affecting the amount of gene product.

Adaptation, Biological↗
PubMed1977

Photic and pentylenetetrazol-induced seizure susceptibility in Macaca mulatta.

Ninety-five out of 100 male Macaca mulatta of varying ages from a restricted habitat in N. India showed no abnormal seizure susceptibility or EEG response to photic stimulation and no electro-clinical features of epilepsy after pentylenetetrazol, 40 mg/kg sc.c. Autopsy studies on the remaining five monkeys with increased seizure proneness revealed depressed skull fractures with cortical trauma in four and a neoplasm in one. Presumably, these factors were responsible for the lowered seizure susceptibility to photic stimulation and pentylenetetrazol activation.

Animals↗
PubMed1976

Central nervous system active 5-oxo-1,4,5,6,7,8-hexahydrocinnolines.

Among a series of 5-oxo-1,4,5,6,7,8-hexahydrocinnolines examined for their CNS activity, 1-(2-diethylaminoethyl)-3-(p-fluorophenyl)-5-oxo-7,7-dimethyl-1,4,5,6,7,8-hexahydrocinnoline (23) and 1-(2-dimethylaminoethyl)-3-phenyl-5-oxo-7,7-dimethyl-1,4,5,6,7,8-hexahydrocinnoline (27) had sedative and anticonvulsant properties and were also acitve in tests used to characterize antidepressants. But their narrow safety margin precluded further follow-up studies. Derivatives 35-38 of 2-(omega-phenacyl)-3-hydrazino-5,5-dimethyl-2-cyclohexenone were active in tests used to characterize antidepressants and were weakly sedative but not anticonvulsant.

Animals↗
PubMed1976

Effect of carbamazepine (Tegretol) on seizure and EEG patterns in monkeys with alumina-induced focal motor and hippocampal foci.

Qualitative and quantitative aspects of chronic carbamazepine (Tegretol) medication on focal seizures and associated interictal EEG abnormalities in Rhesus monkeys with alumina-induced foci in either the sensorimotor cortex or the hipocampus was investigated. In both groups of animals, carbamazepine produced qualitative control of visible seizures and reduced intracortical spike propagation, but did not cause complete normalization of the background EEG; quantitative indices, such as spike density and amount of paroxysmal discharge representative of abnormal EEG activity, were significantly reduced with respect to predrug values during medication and after cessation as well. Threshold to pentylenetetrazol was elevated by carbamazepine in both groups of epileptic monkeys. Aggressivity and other clinical manifestations in monekys with hippocampal foci were markedly reduced by carbamazepine.

Aluminum↗
PubMed1976

A comparison of buoyant density and polypeptides of Drosophila P, C and A viruses.

On the basis of their buoyant densities in CsCl and their capsid polypeptides, three viruses isolated from Drosophila spp. which were originally described as serotypes, are now classified as distinct viruses. The biochemical properties of each virus suggest that it has several key features in common with the mammalian picornaviruses.

Capsid↗
PubMed1975

[Resistance to starvation in insects: importance of the amount of lipid reserves in adult Drosophila melanogaster].

At 25 degrees C, mean survival duration of adults starved after emergence varied from 58 to 112 hours, according to genotype and larval growth conditions. This duration was highly correlated with the amount of lipids. The great variability in the amount of lipids (from 15 to 35% of initial dry weight) seems to have an adaptative significance for adult survival in natural conditions.

Animals↗
PubMed1975

[The discovery, in Drosophila, of viruses belonging to three new groups].

Viruses belonging to three new groups have been discovered by the technique used to detect the Picornaviruses. Virus F was found in two French laboratory stocks of D. melanogaster. Virus G and virus RS came from wild flies: a sample of D. melanogaster from Guiana (virus G) and a mixture of different Drosophila species from Singapore (virus G and virus RS).

Animals↗