The effect of bright light on the retinas of developing albino rats was studied electron microscopically. The newly formed outer-segment lamellar membranes of newborn rats raised in continuous bright light appear to be less sensitive to the damaging effects of light, compared to those of rats raised under normal light conditions for at least two weeks. It seems to take about two days before the membranes show damage from continuous exposure to fluorescent lamps. The same brightness damages the adult outer segments within a few hours. Despite the severe damage to the outer segments, the rest of the retina develops normally for one month, and then the photoreceptor cells undergo degeneration. The retinas that have been exposed to bright light for two weeks after birth show considerable damage, but these retinas regenerate in six months.

Animals↗

PubMed1976

Phagocytosis by the monkey pigment epithelium.

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Animals↗

PubMed1976

Light effect on the synaptic organ of the rat.

The photoreceptor synapses of albino rats show considerable pathologic changes following fluorescent light exposure. The changes in the synapses and in the lamellar membranes of the outer segments occur and progress simultaneously. Membranes proliferate in the paramitochondrial zone of the rod synaptic spherule and fine budding of the smooth endoplasmic reticulum occurs in the cone pedicle within one hour's exposure to the brightness of 500 foot candles. Proliferating paramitochondrial membranes have no cytochrome c oxidase activity and degenerate together with mitochondria by further exposure. The cone pedicles remain relatively intact in photically damaged retina.

Animals↗

PubMedDate not supplied

Hepatic thermogenesis relation to food intake in the conscious rat.

It is well known that the body temperature increases during food intake. However, probably because of high thermal conduction within the body, it is rather difficult to determine the main organ that is the source of participates heat production in association with food intake. Our study revealed that increased temperature in the liver during food intake was more predominant than that in the other parts of the abdomen. To further confirm this, we attempted to measure the temperature of both the liver and blood in the portal vein, simultaneously. The temperature of the liver was always higher than that of the portal blood. This implies that hepatic thermogenesis is continuous. The difference between these two temperatures may indicate whether or not hepatic thermogenesis contributes to the increase in body temperature during food consumption. It becomes apparent that the participation of thermogenesis of the liver, along with that of the brown adipose tissue in body temperature increase, is influenced by the composition of food, such as high or low protein in the diet.

Animal Feed↗

PubMedDate not supplied

Magnetic resonance imaging in Pelizaeus-Merzbacher disease.

Cranial computed tomography of a boy with clinical characteristics of the classic form of Pelizaeus-Merzbacher disease did not reveal a notable abnormality other than enlarged ventricles. Magnetic resonance imaging, however, demonstrated diffuse changes in the white matter with sparing of scattered small areas, suggesting persistent myelin islands which are a typical neuropathologic finding in Pelizaeus-Merzbacher disease. Magnetic resonance imaging appears more useful than computed tomography in confirming the diagnosis of Pelizaeus-Merzbacher disease.

Adolescent↗

PubMedDate not supplied

Characteristics of growth, morphology, contractility, and protein expression of fibroblasts derived from keloid.

Phenotypic alterations of keloid-derived fibroblasts were characterized by comparison with the phenotypes of normal fibroblasts from the same patient. Explant cultures of keloids showed unique features. Keloid explants contracted considerably and reduced their size during culture, whereas the size of normal skin explants remained unchanged. Enlarged cells were found among fibroblasts which had grown out of all the explants and were morphologically distinct from fibroblasts; however, keloid explants produced many more of them than did the normal tissues. The growth rate of fibroblast colonies formed from normal explants was five times higher than keloid explants. Keloid fibroblasts which had been serially cultivated contracted lattices of collagen gels at a rate similar to normal fibroblasts. Proteins extracted from serially cultivated fibroblasts were mapped on polyacrylamide two-dimensional electrophoretic gels. No significant qualitative alterations in protein expression in keloid cells were found as compared with normal fibroblasts. However, some quantitative changes were found between the two. A computer-assisted image analyzer detected 151 polypeptide spots--50 spots (33%) of which increased their amounts in keloid cells, whereas 34 spots (22.5%) decreased in comparison with normal fibroblasts. Sixteen major polypeptides were identified as known proteins with the aid of time-of-flight mass spectrometry. The level of expression of these identified proteins was similar between normal and keloid cells, except stathmin whose expression was suppressed in keloid fibroblasts.

Journal Article↗