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Biomedical subjects

A Harell

Publications and source records attributed to A Harell.

At least 55 records · Page 3Linked to original sources
PubMed1976

Scanning electron microscopy of bone cells in culture.

Embryonic and young rat bone cells have been growing in culture and examined in the scanning electron microscopy (SEM). Compared with cells fixed in situ and taken directly from the animal, the cultured osteoblastic cells were smoother, flatter and more extensive and showed tighter intercellular contacts. Some matrix is formed in culture and undergoes at least partial mineralization as judged by the accumulation of Ca and P measured by energy dispersive x-ray analysis. Findings concerning the morphology of the collagen arrangement were indecisive. Some superficial cells, free of surrounding matrix, resembled osteocytes in normal in vivo bone. This may indicate that a proportion of the extracellular matrix produced by the cultured cells failed to polymerise into recognizable bone matrix, and that osteocytic morphology is not dependent upon the physical characteristics of the bone matrix.

Animals↗
PubMed1976

Growth of the rat femur in diffusion chambers.

Growth in the length of 9-day-old rat femurs, isolated and cultivated in diffusion chambers, was studied for a limited period of 16 days. An increment of 40 per cent of the in vivo length was observed. It could be established that the elongation was due to chondral growth, of which 40 per cent occurred at the proximal and 60 per cent at the distal end of the bone during the 16 days of observation. When the trochanteric or the head epiphyses with their physeal plates were resected, no statistically significant loss in total length occurred. A small but statistically highly significant biphasic growth due to enchondral ossification was found. Resection of the trochanter produced a widening of the cervico-diaphyseal angle (valgisation) of an average of 11.2 degrees. The findings in this series of isolated femurs are --in a general way--similar to those observed in the living animal.

Animals↗
PubMed1976

Effect of caffeine on the motility, viability, oxygen consumption and glycolytic rate of ejaculated human normokinetic and hypokinetic spermatozoa.

In this report the effect of caffeine, IBMX and Cholera toxin on ejaculated human spermatozoa was tested. It was found that caffeine was the most effective drug, and that Cholera toxin was ineffective. Caffeine stimulated motility, preserved viability and increased the glucose, fructose utilization and lactate production of sperm in whole semen and washed sperm. Oxygen consumption however was decreased. These results of the normokinetic ejaculates were defined as a basis for comparison with the response of hypokinetic sperm. A group of 11 hypokinetic ejaculated spermatozoa were treated by caffeine and only five responded to caffeine stimulation by a response, similar to that of normokinetic sperm. They were defined as "responsive." The other group of six patients who did not respond were defined as a "non-responsive" class. The possibility that the in vitro treated sperm of the responsive class ejaculate is suitable for artificial insemination to their wives, is discussed.

Caffeine↗
PubMed1975

The functional metabolism of vitamin D in chicks fed low-calcium and low-phosphorus diets.

Radioactively labelled cholecalciferol was administered continuously to chicks that were fed normal, low-calcium and low-phosphorus diets. It has been possible to show that under such steady state conditions with regard to cholecalciferol, and mineral restriction, the animal reacts by increased accumulation of 1, 25-dihydroxycholecalciferol in the intestinal and the kidney cell, which was associated in the intestine with an increased calcium-binding activity. A similar accumulation of 1, 25-dihydroxycholecalciferol in bone was not noticed. It is proposed that the intestine and the kidney, but not bone, are the main target organs for cholecalciferol in the maintenance of calcium homeostasis, and that both calcium and phosphorus play a role in the regulation of the formation and subsequent function of 1, 25-dihydroxycholecalciferol.

Animals↗
PubMed1975

Under-responsiveness of growth hormone secretion after L-dopa and deep sleep stimulation in obese subjects.

Plasma levels of glucose, free fatty acids and free 11-hydroxycorticosteroids, and serum levels of immunoreactive human growth hormone (HGH) and immunoreactive insulin were determined before and after L-dopa stimulation in 18 obese and six normal-weight subjects. A blunted response of HGH was found in the obese subjects who received 0.5 g L-dopa, but when the dose was doubled, a normal response was obtained in 7 of 13 of the obese subjects. No significant fluctuations in free 11-hydroxycorticosteroid, glucose or insulin levels were found in the obese and normal-weight groups and no increase in HGH was seen in the obese group after the subjects had been asleep for 90 min. In the obese subjects, the blunted response of HGH to stimulation with 0.5 g L-dopa and the lack of HGH increase during sleep are attributed to hypothalamic under-responsiveness, which is considered a basic disturbance in obesity.

11-Hydroxycorticosteroids↗
PubMed1974

Formation of bone tissue in culture from isolated bone cells.

A system is described for the formation of bone tissue in culture from isolated rat bone cells. The isolated bone cells were obtained from embryonic rat calvarium and periosteum or from traumatized, lifted periosteum of young rats. The cells were cultured for a period of up to 8 wk, during which time the morphological, biochemical, and functional properties of the cultures were studied. Formation of bone tissue by these isolated bone cells was shown, in that the cells demonstrated osteoblastic morphology in light and electron microscopy, the collagen formed was similar to bone collagen, there was mineralization specific for bone, and the cells reacted to the hormone calcitonin by increased calcium ion uptake. Calcification of the fine structure of the cells and the matrix is described. Three stages in the calcification process were observed by electron microscopy. It is concluded that these bone cells growing in vitro are able to function in a way similar to such cells in vivo. This tissue culture system starting from isolated bone cells is therefore suitable for studies on the structure and function of bone.

Alkaline Phosphatase↗