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Biomedical subjects

J West

Publications and source records attributed to J West.

At least 199 records · Page 11Linked to original sources
PubMed1981

Effect of incubation temperature on the frequency of sister chromatid exchanges in Bloom's syndrome lymphocytes.

The effect of incubation temperature on the frequency of sister chromatid exchange (SCE) has been studied in blood cultures from three Bloom's syndrome (BS) patients, three controls, and three BS heterozygotes. All cell types show slight increases of SCE at 39 degrees C while at 35 degrees C and 32 degrees C, SCE is reduced considerably in BS and slightly increased in normal cells. Prolonging lymphocyte culture to 140 h and adding BUdR for the last two S periods causes a similar decrease in the percentage of SCE in normal and BS cells but, while the latter show a further reduction if they are incubated at 32 degrees C during BUdR labelling, the normal cells show an increase. Therefore, BS and control lymphocytes respond similarly to changes in incubation time and differently to changes in incubation temperature. The possibility that the discrepant behaviour of the BS and control cultures may be due to different growth kinetics of their B and T lymphocytes has been discussed but considered unlikely. Since low temperature lengthens the cell cycle, it has been suggested that our findings and those published by others on co-cultivation experiments (except those of Tice et al. 1978) can be explained by assuming that slow growth reduces SCE in BS cells. This, and unpublished observations (Giannelli et al. 1981), suggest that some imbalance in the factors responsible for DNA replication may exist in BS and possibly account for the high level of SCE.

Bloom Syndrome↗
PubMed1981

Effects of hyperthermia and radiation on mouse testis stem cells.

The response of mouse testis stem cells to hyperthermia and combined hyperthermia-radiation treatments was assayed by spermatogenic colony regrowth, sperm head counts, testis weight loss, and fertility. With the use of spermatogenic colony assay, thermal enhancement ratios at an isosurvival level of 0.1 were 1.27 at 41 degrees, 1.80 at 42 degrees, and 3.97 at 43 degrees for testes exposed to heat for 30 min prior to irradiation. Sperm head counts were reduced by heat alone from a surviving fraction of 0.58 at 41 degrees to 0.003 at 42.5-43.5 degrees. Curves for sperm head survival measured 56 days after the testes had been heated for 30 min prior to irradiation were biphasic and showed a progressive downward displacement to lower survival with increasing temperature. The 41, 42, and 43 degrees curves were displaced downward by factors of 2, 58, and 175, respectively. The proportion of animals remaining sterile after 30 min of heat (41-43 degrees) and the median sterility period in days increased with increasing temperature. The minimum sperm count necessary to regain fertility was 13% of the normal mouse level.

Animals↗
PubMed1977

Circulatory response to systemic infusion of norepinephrine in the pregnant ewe.

Seven pregnant ewes from 100 to 137 days of gestation were infused with systemic doses of norepinephrine and uterine arterial flow dose-response curves were determined. A constant infusion of norepinephrine at a mean rate of 0.24 mug per minute per kilogram led to a 39.3 per cent decrease in total uterine arterial blood flow as measured with isotope-labeled microspheres while systemic pressure was unaltered. At this dose the reduction in endometrial blood flow (--64 per cent) was significantly greater than that in either the myometrium (--45 per cent) or placental cotyledons (--31 per cent) (p less than 0.005). Significant decreases in blood flow to small bowel, skeletal muscle, vagina, cervix. Fallopian tubes, kidneys, spleen, pancreas, and mammary gland were documented. There were no significant increases in blood flow. This study demonstrates that during the period or pregnancy studied, the overwhelming response to norepinephrine is vasoconstriction and that the vascular beds of all the tissues of pregnant uterus are sensitive to the alpha-adrenergic effects of norepinephrine.

Animals↗
PubMed1975

Sialoadenosis produced by drug-treatment of hypertonicity. II. Experimental studies on the effects of guanethidine (Ismelin) on the submaxillary glands of the rat.

48 rats were treated with guanethidine (Ismelin) in order to study the side-effects on the submaxillary glands following application of a routinely used antihypertensive substance. In contrast to guanethidine-treated parotid glands, no retention of alpha-amylase was observed. The amylolytic activities of the glands are decreased both after treatment for 24 hrs and when a 3 week treatment had been followed by a 2 week recuperation period. This decrease of total amylase content runs parallel with alterations in the alpha-isoamylase patterns of the submaxillary glands. Furthermore, gland growth is inhibited by the guanethidine-mediated "pharmacological sympathectomy". We interpret these proteodyschylic changes of the submaxillary glands as a pharmacologically induced peripheral neurogenic sialoadenosis.

Amylases↗