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Biomedical subjects

S Young

Publications and source records attributed to S Young.

At least 307 records · Page 17Linked to original sources
PubMed1979

Role of vitamin E in the etiology of spontaneous hemorrhagic necrosis of the central nervous system of fetal hamsters.

The intraperitoneal inoculation of pregnant hamsters with vitamin E during the first half of gestation reduced the severity or eliminated the occurrence of grossly observable effects of spontaneous hemorrhagic necrosis (SHN) of the central nervous system in their offspring and improved the pre-weaning viability of their litters. The addition of corn oil (16%) or linoleic acid (8%) to a ration associated with the occurrence of SHN in fetal hamsters enhanced the incidence and severity of the disease, and these effects were moderated by inoculation of the dams with vitamin E. Experimental data indicated that, among multifactorial contributions to the cause of SHN in hamsters, vitamin E availability and levels of dietary polyunsaturated fatty acid played a significant and interrelated role.

Animals↗
PubMed1979

The carcinogenicity of 15,16-dihydro-11-methyl-cyclopenta[a]phenanthren-17-one.

Direct comparison of skin-tumour induction by 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one (I) and by benzo[a]pyrene on mouse skin, both by repeated application or by initiation with a single dose followed by promotion with croton oil, demonstrated that these two carcinogens have similar potency. After repeated application of (I) the mean latent period for skin-tumour induction was linearly related to the logarithm of the dose over a 10-fold dose range. Under these conditions, application of the aryl-hydrocarbon-hydroxylase inhibitor 7,8-benzoflavone together with (I) inhibited tumour induction by about 40%. By contrast, in the 2-stage experiment, little effect on tumour incidence or latent period was observed when this inhibitor was applied with the single initiating dose of (I). Co-administration of the epoxide-hydratase inhibitor 1,1,1-trichloropropene oxide caused enhancement by shortening the latent period. After s.c. injection of (I) into mice, a similar number of tumours was induced on skin remote from the site of injection by promotion with corton oil begun either one week or 6 months after initiation. Gastric instillation of (I) into female rats induced mammary adenocarcinomas.

Animals↗
PubMed1979

Intraocular melanoma in a horse.

Sudden unilateral blindness occurred in a 7-year-old grey gelding Quarterhorse. Ophthalmoscopy revealed a pigmented mass arising from the nasal ciliary body of the right eye and extending around the posterior surface of the lens, and there were pigmented particles in the vitreous. Examination of the enucleated globe showed a circumscribed, black, dense and symmetrically ovoid mass with sessile attachment to the nasal ciliary region and extension to posterior lens capsule, vitreous and along the vitreal face of the detached retina to the optic papilla. The mass was composed of heavily pigmented, plump, polyhedral cells that invaded the vitreous and the inner limiting membrane of peripapillary retina and optic papilla. It was considered to be a primary, malignant, intraocular melanoma arising from a large uveal nevus.

Animals↗
PubMed1978

An observational study of caretaking behavior of male and female mice housed together.

A time-sampling procedure was employed to examine the caretaking behavior of male mice housed with lactating females and their litters, and to investigate the effects of the male's presence on the behavior of the female. The incidences of 14 categories of behavior were recorded over 20 hr distributed throughout the period of lactation. The development of litters was monitored by regular weighing. The results show, contrary to earlier findings, that males display just as much caretaking behavior as females. Differences in other forms of behavior can be related to the increased nutritional needs of the nursing mothers. The presence of the male seems to have very little influence on the behavior of the female and no effect at all upon the physical development of the litter.

Animals↗
PubMed1978

Hemorrhagic necrosis of the central nervous system of fetal hamsters: litter incidence and age-related pathological changes.

The occurrence, anatomic distribution, and character of lesions of spontaneous hemorrhagic necrosis (SHN) are reported in each hamster fetus of two affected litters examined on the fifteenth day of gestation and in selected individuals of other affected litters on the twelfth, thirteenth, and fourteenth days of gestation. The pathologic process seems primarily to affect the capillary vasculature of the central nervous system and shows a predilection for rapidly growing and differentiating regions of the fetal forebrain, thalamus, and brain stem. Lesions demonstrable in members of affected litters of susceptible stocks are of a progressive character, increasing both in severity and topographic extend with increasing fetal age and growth. Spontaneous patterns of regression and recurrence of SHN disease in susceptible stocks may reflect variable physiologic factors in the intrauterine environment.

Animals↗
PubMed1978

Congenital deformities produced in hamsters by potato sprouts.

Dried gound potato sprout preparations from seven varieties produced congenital deformities in one strain of hamsters. Incidence of affected litters varied from 8 to 25%, depending on potato variety. Certain steroidal solanum and veratrum alkaloids produced similar defects. Neither peel nor tuber material was teratogenic from one of the potato varieties with highly teratogenic sprouts.

Abnormalities, Drug-Induced↗
PubMed1978

Excision of hydrocarbon-DNA adducts and consequent cell survival in normal and repair defective human cells.

Survival curves for normal human cells and xeroderma pigmentosum variant cells (XP4BE) after ultraviolet radiation were indistinguishable. In comparison, cells from xeroderma pigmentosum complementation group A (XP12BE) were very sensitive to ultraviolet radiation. Complementation group C (XP2BE) cells were almost as sensitive as group A cells. These survival phenomena parallel to known unscheduled DNA synthesis responses of these cells to ultraviolet radiation, which, compared with normal cells, are: XP4BE, 100%; XP2BE, 20%; XP12BE, 2%. The relative capacities of these cells to excise 7-bromomethylbenz[a]anthracene-DNA adducts and to survive treatment with the carcinogen were similar to the responses to ultraviolet irradiation, except that the XP2BE cell line both excised and survived this damage far better than anticipated from its response to ultraviolet irradiation. Moreover, whilst in the normal cells and variant cells the ratio of hydrocarbon-adenine adduct to hydrocarbon-guanine adduct remaining in DNA decreased notably with excision, this ratio did not change significantly with excision in the XP2BE cell line. The relationship between greater excision capacity and increased cell survival in the experiments with the chemical carcinogen indicates that the unexcised damage is responsible for the cell-killing action of this agent. The different relative repair and survival responses of these cell lines to ultraviolet irradiation on the one hand, and to 7-bromomethylbenz[a]anthracene chemical carcinogen treatment on the other, indicate that in at least one of these cell lines (XP2BE), and possibly in all the lines, different cellular mechanisms are involved in the repair of DNA damage resulting from ultraviolet irradiation and that resulting from the chemical carcinogen treatment.

Benz(a)Anthracenes↗
PubMed1978

Surface membrane characteristics of cells from human acute monocytic leukaemia.

The clinical and laboratory features of 4 patients with acute monocytic leukaemia are described. Surface membrane receptor studies of these patients have shown increasing strength of receptor expression occurs with increasing morphological maturity of the monocyte. In addition, the study shows that expression of membrane receptors can vary from patient to patient and also with time and treatment in an individual patient. A further finding has been the loss of positivity with specific anti-monocyte serum when the disease becomes refractory to therapy.

Adult↗
PubMed1978

Diversion of retinal blood flow by photocoagulation.

The normal distribution of the retinal blood flow in the cat eye was modified by photocoagulation to part of the territory supplied by a major arteriole, or by occluding a branch. Volume inflow to the treated territory was reduced, and there was also a reduction of linear flow and, to a less extent, calibre in the parent vessel. Branches of the parent vessel supplying untreated territory showed marginal increases of volume inflow. An autoregulatory effect appeared to be operative. The relevance of these findings to clinical panretinal photocoagulation is discussed.

Animals↗
PubMed1978

Somatosensory-evoked potentials elecited by bilateral stimulation of the median nerve and its clinical application.

Somatosensory evoked potentials (SEPs) elicited by bilaterally simultaneous median nerve stimulation (BS) were studied in 28 normal subjects and in 20 patients with various cerebral lesions. In normals, SEP'S evoked by BS were symmetric between the homologous areas of the two hemispheres and resembled the response contralateral to unilateral stimulation (US). In patients with a cerebral lesion, BS responses were not only asymmetric but often differed in wave form from the response of the affected hemisphere to contralateral US. These alterations were attributed to the cumulative interactions of the anomalous contralateral and ipsilateral components. The additional use of BS made it possible to demonstrate SEP abnormalities that might have been regarded as normal or equivocal if only the US method had been used. The neurophysiologic mechanisms of the origin of SEP are discussed.

Adult↗
PubMed1978

Lumbar spondylectomy in the subhuman primate.

Removal of the 2nd or 3rd lumbar vertebrae (or both) has been accomplished in the subhuman primate (Macaca mulatta). Variations between this animal and the dog in posture, vertebral column anatomy, and spinal cord blood supply made no apparent difference in the results when compared with those in previous experiments. All macaques were able to clinb and to use their hind legs in a normal manner within 3 days after surgical operation. Once hair had regrown over the surgical incision, persons not familiar with the animals were not able to identify the animals that had undergone surgical operation. If a single vertebra was removed, use of spinous process and a single vertebral body plate was sufficient to stabilize the vertebral column. Except for 1 rhesus macaque whose spinous process plates were removed 20 days after the operation, vertebral columns of macaques (n = 3) that underwent single spondylectomy healed in nearly normal alignment. With the removal of 2 lumbar vertebrae, the previously described stabilization procedure was not sufficient to prevent kyphotic deformity of the vertebral column. Spinous process plates from 1 macaque were removed after 64 days. However, all these macaques (n = 3) could climb and use their legs as well as others in the colony.

Animals↗