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Biomedical subjects

G S George

Publications and source records attributed to G S George.

5 recordsLinked to original sources
PubMed1995

A comparison of subtalar joint maximal eversion while jogging on the minitrampoline and floor.

The jogging minitrampoline is a common tool for exercise and rehabilitation that is lauded as helpful in reducing lower extremity stresses. The deformable bed of the minitrampoline may result in altered jogging mechanics of the subtalar joint, potentially leading to uncharacteristic mechanics of the lower extremity. The purpose of this study was to examine eversion of the subtalar joint in subjects jogging on the minitrampoline vs. a wooden floor surface. Subjects were instrumented with a flexible electrogoniometer (elgon) taped from the heel to the gastrocnemius along the Achilles tendon. The elgon was interfaced to a personal computer. Data were examined for the average maximal eversion values of five steps during jogging in two experiments. Results of the first experiment (N = 27) indicated significantly greater mean maximal eversion angles while jogging on the minitrampoline than on the floor. The second experiment involved 10 male and 10 female subjects jogging for 20 minutes with a counterbalanced sequence of jogging conditions, alternating between the floor and the minitrampoline. The second experiment indicated that maximal eversion angles were significantly greater on the minitrampoline than on the floor and increasing jogging time resulted in greater eversion angles and a significant interaction between jogging condition and time. Results suggest that people who should avoid valgus deviations to the lower leg should not jog on the jogging minitrampoline.

Adult↗
PubMed1990

Reproducible estimation of retinal vessel width by computerized microdensitometry.

An objective method for reliably estimating the width of retinal vessels is presented. A computerized microdensitometer scans film negatives of fundus photographs and reconstructs black and white images of the fundus on a visual display terminal. After this initial scan, a desired region of a retinal vessel is selected with moveable cursors, and a cross-sectional density profile through the vessel is plotted. Vessel width is determined by the half-height width of the profile of the minimum (least transmitting) and average background film densities. Measurement sites can be accurately reproduced on different negatives by landmark mapping. A series of ten fundus photographs were taken of three healthy human eyes, and the width of the superior temporal vein was measured in two places on alle negatives. The coefficient of variation of the six sets ranged from 1.2 and 3.4% with an average of 2.2%.

Analysis of Variance↗
PubMed1983

Retinopathy of prematurity: a new look at an old disease.

The neovascular changes of the retinopathy of prematurity can occur in premature infants in three settings: (1) when high levels of supplemental oxygen are administered, neovascularization usually commences shortly after cessation of oxygen therapy; (2) when supplemental oxygen is given for long periods of time, neovascularization can develop while the infant is still receiving oxygen; and (3) neovascularization can occur without exposure to any supplemental oxygen. We propose a model which can explain the occurrence of the retinopathy of prematurity in all these settings. Our model demonstrates that whenever the retinopathy of prematurity occurs, arterial oxygen levels are inappropriately high in relation to the stage of retinal vessel development, even in premature neonates not given supplemental oxygen. The inhibitory effect of these elevated oxygen tensions upon carbon dioxide removal is indicated as a possible cause of neovascularization by leading to tissue acidosis and vasodilatation.

Carbon Dioxide↗