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Biomedical subjects

S Molnar

Publications and source records attributed to S Molnar.

At least 55 records · Page 3Linked to original sources
PubMed1977

Functional implications of primate enamel thickness.

Recent evolutionary interpretations of Hominoidea have postulated functional relationships between tooth form, diet and masticatory biomechanics. A major consideration is the durability of the tooth under certain dietary conditions. Teeth with low cusps and thicker enamel are able to withstand heavy mastication of abrasive food bolus for a longer period. When comparisons are made between species of higher primates the variables of tooth size, cusp morphology, and enamel thickness appear to be related but until now no systematic analysis has been made to determine the functional relevance of several dental dimensions. This study provides data gained from comparisons of dentition of nine species of primates. Histological sections were made of the post canine teeth and 21 dimensions were compared. The relevant dimensions identified serve to withstand dental wear. The distribution of thicker enamel corresponded to the observed wear planes. Humans had thicker enamel than pongids while the macaque had the thinnest. These preliminary results tend to support theories which explain low, thick, enameled cusps in hominids.

Animals↗
PubMed1976

Inhibition of spontaneous contractility of the human and the rabbit fallopian tube by potassium.

Spontaneous contractions of circular and longitudal muscle of the ampulla and isthmus of human and rabbit Fallopian tubes were recorded isometrically. Addition of K+ to tissue in K+-free medium always caused immediate inhibition of spontaneous contractility. K+-induced inhibition was prevented by ouabain and reversed by removal of K+. It is suggested that K+ caused inhibition of contractility by activating electrogenic Na+ pumping with resultant hyperpolarization of the muscle cells.

Animals↗
PubMed1976

Characteristics of responses of isolated human fallopian tube to transmural stimulation and to sympathomimetic amines.

The responses of circular and longitudinal muscle of human fallopian tube to transmural stimulation and sympathomimetic amines have been investigated. It was found that tissues from the earlier part of the menstrual cycle (i.e., estrogen dominant) were less responsive to all stimuli than those from the middle or late phase of the cycle. Although excitatory alpha responses of ampulla and isthmus could be observed, the predominant response of ampulla and isthmus, in all phases of the menstrual cycle, to (--)-noradrenaline and transmural stimulation was inhibition of spontaneous activity. The inhibitory response to transmural stimulation, was abolished by tetrodotoxin and guanethidine. The inhibitory responses to transmural stimulation and (--)-noradrenaline were reversed by propranolol. These findings show that the response of tissues to transmural stimulation resulted from release of noradrenaline from adrenergic nerves, and subsequent action on inhibitory beta adrenergic receptors.

Electric Stimulation↗
PubMed1975

Mineral metabolism and microstructural defects in primate teeth.

There are numerous structural defects that occur in primate teeth due to variable calcification during certain growth stages. These interruptions are usually areas of hypomineralization in enamel and dentin which are referred to as Striae of Retzius and Hunter Shreger bands in the enamel or Incremental Lines of von Ebner and Contour Lines of Owen in the case of the dentin. The frequency of occurrence of these variations in mineralization can be related to such factors as growth tempo, dietary quality, state of health, and past disease episodes. Another structure that appears in the dentin is a region that fails to calcify and is referred to as Inter-globular Dentin. Our studies have shown that the microstructural quality of different species' dentition varies widely. Samples obtained from certain fre-ranging cercopithcoids show that these species have the least hypomineralizations while man has the most. Other primate species range between these two extremems with the pongids nearer to man in these characteristics, as previously noted by Sognnaes. Additionally, out initial study shows a great deal of diversity between prehistoric human populations in the microstructural quality of their teeth. We offer the tentative explanation that this variation is due to differences in the calcitying properties of the diet and hence a difference in the general state of their health.

Adolescent↗