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Biomedical subjects

R Vito

Publications and source records attributed to R Vito.

6 recordsLinked to original sources
PubMed1999

Virgin olive oil volatile compounds from lipoxygenase pathway and characterization of some italian cultivars.

Fruits from seven different varieties of Olea europaea L., grown in the same environmental conditions, were harvested in two succeeding years at the same ripening degree and immediately processed. The oils obtained were submitted to gas chromatographic determination of the volatile compounds extracted by dynamic headspace technique. The results demonstrated that the accumulation of the different metabolites in the oils obtained from the various cultivars were strictly connected with the varietal parameter because of the enzyme differences genetically determined. This feature made possible the differentiation of the examined cultivars on the basis of the percent of each metabolite from the enzymatic transformation of 13-hydroperoxides of linolenic acid. Oils from Picual and Koroneiki varieties cultivated in Spain and Greece, respectively, showed contents of volatiles very similar to those detected in the oils of the same varieties cultivated in Italy, proving that they were not significantly influenced by the environmental conditions.

Dietary Fats, Unsaturated↗
PubMed1998

Mechanical analysis of heterogeneous, atherosclerotic human aorta.

An experimental technique was developed to determine the finite strain field in heterogeneous, diseased human aortic cross sections at physiologic pressures in vitro. Also, the distributions within the cross sections of four histologic features (disease-free zones, lipid accumulations, fibrous intimal tissue, and regions of calcification) were quantified using light microscopic morphometry. A model incorporating heterogeneous, plane stress finite elements coupled the experimental and histologic data. Tissue constituent mechanical properties were determined through an optimization strategy, and the distributions of stress and strain energy in the diseased vascular wall were calculated. Results show that the constituents of atherosclerotic lesions exhibit large differences in their bilinear mechanical properties. The distributions of stress and strain energy in the diseased vascular wall are strongly influenced by both lesion structure and composition. These results suggest that accounting for heterogeneities in the mechanical analysis of atherosclerotic arterial tissue is critical to establishing links between lesion morphology and the susceptibility of plaque to mechanical disruption in vivo.

Aged↗
PubMed1992

Micro-architecture and composition of artery walls: relationship to location, diameter and the distribution of mechanical stress.

PURPOSE: We reviewed the structural basis of the mechanical properties of the arterial wall, in order to establish a coherent micro-anatomical basis for the differences in compliance among different arteries and a framework for assessing changes in the mechanical properties of specific individual arteries in relation to changing physical stresses. DATA IDENTIFICATION: The data and concepts presented here were derived from both earlier and ongoing work. Features that assure stability and integrity in relation to blood flow (wall shear stress) and pressure (mural tensile stress) were examined. Particular attention was paid to the morphogenetic and biosynthetic means by which arteries adapt to normal or abnormal modifications of these forces, particularly in relation to growth, location in the arterial tree and geometric configuration. RESULTS AND CONCLUSIONS: Thickness, composition and architecture of the artery wall, including thickness and composition of the intima, are normally determined by the stresses imposed by pressure and flow. Vessel radius is closely associated with flow, so that a normal baseline level of mean shear stress of about 15 dyn/cm2 is maintained or restored. Wall thickness and composition are determined by wall tension in relation to pressure and radius. Baseline levels of tensile stress differ with location but appear to be similar for homologous vessels. Changes in flow that modify the radius also modify wall tension. Changes in wall thickness and composition are likely to cause changes in compliance, due to altered flow and/or pressure patterns; these changes in compliance may be adaptive rather than destructive. Changes in the compliance of specific arteries over time may be used to evaluate the progression and severity of the conditions underlying these changes.

Animals↗
PubMed1975

Poststenotic dilatation: arterial wall mechanics in response to vibration.

A study of the relationship between the mechanical response of human iliac arteries subjected to sinusoidally varying dynamic pressures superimposed on a static pressure of 100 mm Hg (1mm Hg = 133 N/m2) and the development of arterial dilatation, with particular reference to poststenotic dilatation has been conducted. In 13 experiments, optical measurements of the amplitude of vessel wall movements in response to dynamic pressures of amplitude 5 mm Hg peak to peak indicated the presence of at least one, and at most four resonance peaks for frequencies in the mean range 0-100 Hz. Four specimens were vibrated at resonance and four at frequencies 15 Hz higher than resonance, in response to a dynamic pressure of 5 mm Hg peak to peak for 3 h. All specimens exhibited some dilatation, the average percentage increase in diameter being in the range 0.22 to 0.42% per hour. In four additional experiments, the dynamic pressure was doubled at constant frequency. This resulted in an increased amplitude of vibration and additional dilatation at an increased rate. It is concluded that the dynamic stresses present in the vessel influence the rate of dilatation.

Acoustic Stimulation↗