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Biomedical subjects

E Kaplan

Publications and source records attributed to E Kaplan.

At least 253 records · Page 14Linked to original sources
PubMed1976

Evaluation of perfusion with the 81Rb-81mKr generator.

The development of the 81Rb-81mKr generator-delivery system has made available an ultrashort (13-sec) half-life radionuclide for continuous, constant-rate delivery as a gas, or as an isotonic, nonionic solution in 5% dextrose and water. This system has been evaluated and applied to the scintigraphic imaging of various organs and anatomic regions by intravenous and intraarterial infusion and by inhalation and deglutition. This diffusible, noble gas is inert chemically and biologically. When the gas is administered intraarterially, the volume of tissue being perfused may be defined with the scintillation camera. The 13-sec half-life is of a similar magnitude to the rate of capillary exchange, producing a heterogeneous image with steady-state administration in which the intensity of detectable radioactivity is proprotional to the time of diffusion into the tissue. This system appears capable of defining the rate of capillary exchange and the moment-to-moment changes brought about by vasoactive stimuli in specific organs.

Animals↗
PubMed1976

The "tip-of-the-tongue" phenomenon in aphasia.

Forty-two male aphasics, classified as Broc's, Wernicke's, anomic, and conduction, were examined for their ability to partially retrieve acoustic features of words they could not provide in a confrontation naming task (the "tip-of-the-tongue" phenomenon). The results indicated that conduction aphasics were superior to Wernicke's and anomic asphasics in their ability to identify both the first letter and the syllabic length of the words they could not name. Since the aphasic groups were comparable in their naming difficulty, the findings could not be attributed to degree of wordfinding impairment. The difference between groups that were obtained using the TOT technique are discussed with regard to differences in the word finding process.

Aphasia↗
PubMed1976

Effect of calcium on RNA and protein synthesis in the hypertrophied myocardium.

Myocardial protein synthesis was elevated 7 days after rats were subjected to experimental aortic outflow obstruction. Although RNA synthesis was not increased at this time, RNA concentration was elevated and may have provided for the observed increase in protein synthesis. A possible basis for the persistence of the high RNA levels was a decrease in the degradation of RNA. The increase in intracellular calcium observed in hypertrophied tissue may be involved in the maintenance of RNA concentration and in the increased rate of protein synthesis.

Animals↗
PubMed1975

A longitudinal study of red cell enzymes in infants of low birth weight.

A longitudinal study of red cell enzyme activity in newborn infants of low birth weight has been conducted over the first 2 months of life. The enzymes investigated are acetylcholinesterase (EC 3.1.3.7), an integral part of the red cell membrane and subnormal in ABO hemolytic disease of the newborn; and glucose-6-phosphate dehydrogenase (EC 1.1.1.49), an intracellularly-located, sex-linked enzyme, implicated in neonatal jaundice and of significance in drug-induced hemolytic anemias. Acetylcholinesterase activity, which is lower in normal full-term infants and in low birth weight infants than in adults, was further diminished during the initial weeks of life of the infants of low birth weight and the higher levels of activity, characteristic of adult red cells, had not appeared by 2 months of age. By contrast, red cell glucose-6-phosphate dehydrogenase activity, which is higher in full-term newborn infants and in infants of low birth weight than in adults, did not diminish as a function of age and the lower adult levels were not discernible by 2 months of life.

Acetylcholinesterase↗
PubMed1975

Properties of visual cells in the lateral eye of Limulus in situ.

Excitatory properties of visual cells in the lateral eye of Limulus, investigated by optic nerve recordings in situ, differ significantly from the properties of cells in the classical, excised eye preparation. The differences suggest the possibility that two receptor mechanisms function in the eye in situ: one mechanism encodes low light intensities and the other responds to high intensities. The two mechanisms enable each ommatidium to respond over an intensity range of approximately 10 log units. This hypothesis was tested by measuring the increment threshold and the spectral sensitivity, by studying light and dark adaptation, and by analyzing the variability of the impulse discharge. Although the results do not conclusively identify two receptor mechanisms, they indicate that a process or a part of a process that functions in the eye in situ is abolished by excising the eye or cutting off its blood supply.

Action Potentials↗