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Biomedical subjects

F Larin

Publications and source records attributed to F Larin.

At least 19 recordsLinked to original sources
PubMed1983

The size and structure of the DNA genome of symbiont xenosome particles in the ciliate Parauronema acutum.

The size and structure of the DNA genome of xenosomes, bacterial endosymbionts of the marine hymenostome ciliate, Parauronema acutum 110-3, were investigated. Renaturation kinetic measurements, determined optically and by hydroxyapatite chromatography, suggested a genome size of 0.34 x 10(9) daltons. Sedimentation rate measurements of DNA gently released from the symbionts yielded molecules of comparable size. The analytical complexity, determined chemically, was 3.03 x 10(9) daltons. Consistent with these and other data is a model for the structure of the symbiont genome in which the DNA exists in the form of nine circularly permuted, double-stranded DNA molecules of unique sequence, each of molecular weight 0.34 x 10(9). It is suggested that xenosomes and certain symbionts found in ciliated protozoa may be extant forms of once free-living bacteria that have adapted to the intracellular environment.

Animals↗
PubMed1975

Brain H-3-catecholamine metabolism in experimental cerebral ischemia.

Unilateral ligation of a common carotid artery in gerbils causes a major depletion of brain dopamine, which is most marked in brain regions known to receive dopaminergic projections. To determine whether this depletion reflects release of stored dopamine, a radioactive label (H-3-dopamine) was introduced into brain dopamine pools 4 hours prior to ligation. Twenty-four hours later, brain H-3-catecholamines were profoundly depressed ipsilateral to the lesion among animals exhibiting clinical signs of stroke. Within brain regions known to receive dopaminergic projections, common carotid ligation also was associated with a selective decrease in the concentration of H-3-deaminated metabolites. These data suggest that cerebral ischemia is associated with release of catecholamines, as well as with impaired oxidative metabolism of catecholamines.

Animals↗
PubMed1974

Brain catechol synthesis: control by train tyrosine concentration.

Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.

Alanine↗
PubMed1972

Control of the rat pineal gland by light spectra.

Control of pineal hydroxyindole-O-methyl transferase (S-adenosylmethionine:N-acetylserotonin-O-methyl transferase; EC 2.1.1.4) by light spectra was determined by placing groups of rats previously housed in continuous darkness under one of seven light sources for 96 hr; rats were exposed to the same intensity of irradiation. Activity of the enzyme was lowest in rats maintained under green light (lambda peak = 530 nm); blue and yellow light were somewhat less effective; red and ultraviolet light did not significantly lower the enzyme activity. The suppression of pineal hydroxyindole-O-methyl transferase by full-spectrum light sources could be correlated with the proportions of their spectral outputs in the blue-green-yellow range. These observations suggest that the retinal photopigment that mediates pineal responses to light in rats is rhodopsin or another compound with similar absorption properties.

Analysis of Variance↗