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Biomedical subjects

R Jones

Publications and source records attributed to R Jones.

At least 883 records · Page 49Linked to original sources
PubMed1983

Effects of prolactin on testosterone-induced growth and protein synthesis in rat accessory sex glands.

The relative importance of testosterone and prolactin in regulating growth and protein synthesis in rat accessory sex glands has been investigated. Protein synthesis was measured by incubating tissue minces in vitro with [35S]methionine and analysing labelled proteins on polyacrylamide gels containing sodium dodecyl sulphate. Plasma prolactin was assayed by radioimmunoassay. Results showed that castration for 8 days significantly reduced wet weights and total protein synthesis in the ventral prostate, dorsolateral prostate and caput epididymidis, but that these effects could be reversed by exogenous testosterone. Similarly, the specific incorporation of [35S]methionine into four polypeptides in the ventral prostate, two polypeptides in the dorsolateral prostate and two polypeptides in the caput epididymidis was lowered by castration but markedly stimulated by testosterone. Acute or chronic administration of 2-bromo-alpha-ergocryptine to animals in combination with testosterone had no significant effect on any of the parameters measured, although the drug reduced circulating prolactin to undetectable levels. In addition, exogenous prolactin given alone, or in combination with testosterone, to hypophysectomized rats had no effect on general or specific protein synthesis. The induction of hyperprolactinaemia in immature or mature rats with pituitary homographs had no effect on testosterone-stimulated growth of any accessory gland, although it caused a significant stimulation of total protein synthesis in the dorsolateral prostate and coagulating glands. However, this was a generalized effect as it did not increase the specific incorporation of [35S]methionine into androgen-dependent proteins. The results do not indicate a major role for prolactin in regulating androgen responsiveness of male accessory sex glands in the rat.

Animals↗
PubMed1983

Assessment and training of brain-damaged drivers.

This paper describes a driving assessment and training program that is primarily for patients discharged from the hospital and who may be experiencing residual impairment from some form of brain damage. Assessment is carried out by an occupational therapist and consists of several off-road tests (vision, reaction timing, computerized preview tracking test, general medical/psychological appraisal), and an on-road test. More than 300 patients have been seen since the program's inception in 1977, and trends indicated by their assessment results are: twice as many male as female referrals; a low fail rate among nonbrain-involved patients; diagnosis as a poor predictor of outcome; no significant difference between fail rates of right and left stroke patients; significant difference in average tracking task performance between the Pass, Borderline, and Fail assessment groups. Off-road testing complements, rather than replaces, on-road testing. Thirty-eight of the 300 patients were given special training, and 15 of these were unable to reach an acceptable level. This reflects a difficulty in predicting the outcome of unlicensed patients with severe disabilities.

Adolescent↗
PubMed1983

DDAVP (1-desamino-8-D-arginine vasopressin): an antagonist of the pressor action of endogenous vasopressin?

The pressor effect of arginine vasopressin (AVP) is thought to be mediated by a calcium-dependent mechanism (V1-receptor) whereas its antidiuretic effect depends on c-AMP (V2-receptor). 1-Desamino-8-D-arginine-vasopressin (DDAVP) is possibly an antagonist on the V1-receptor and may therefore be used for assessing the role of endogenous AVP in blood pressure regulation. This possibility was tested using the following models: aggregation of human platelets, renin secretion by rabbit kidney slices, and blood pressure and renin responses in normal human subjects (n = 11) and patients with autonomic insufficiency (n = 4). AVP 10(-10)-10(-7) mol/l caused dose-dependent platelet aggregation and inhibition of renin secretion. These effects were absent in a calcium free medium or in the presence of the calcium antagonist verapamil 5 X 10(-5) mol/l. DDAVP up to 10(-5) mol/l had no effect but shifted the dose-response curves of AVP to the right. AVP infusion into normal subjects is known to lower heart rate and plasma renin with little change in blood pressure. DDAVP 400 ng/kg in 10 min caused no change in systolic pressure but diastolic pressure was lowered by 14 +/- 2 mmHg (mean +/- s.e.m.). Heart rate rose by 24 +/- 2 beats/min and renin rose from 21 +/- 4 to 57 +/- 9 muu/ml (P less than 0.01). In the patients with autonomic insufficiency both systolic and diastolic pressures fell by 20-50 mmHg after DDAVP 200 ng/kg without any change in heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Association of epididymal secretory proteins showing alpha-lactalbumin-like activity with the plasma membrane of rat spermatozoa.

Three hormonally regulated proteins with mol.wts of 18 500, 19 000 and 23 000 have been shown to associate with the plasma membrane of spermatozoa during maturation in the epididymis. All three proteins showed some alpha-lactalbumin-like activity, suggesting that they may act in concert with epididymal glycosidases and glycosyltransferases to regulate the modification of sugars on membrane-bound glycoproteins.

Animals↗
PubMed1982

ADP-ribosylation of nuclear proteins in mouse testis.

The nuclear acceptor proteins for poly(ADP-ribose) were investigated in mouse liver and testis. In liver, histones are ribosylated preferentially, whereas in testis the major acceptors are non-histone proteins. An analysis of the purified testicular acceptor proteins suggests that they are high- and low-mobility-group-like proteins.

Amino Acids↗
PubMed1982

Chlamydia and NSU.

Explore the source record for details and available documents.

Chlamydia Infections↗
PubMed1982

Identification of androgen-dependent proteins synthesized in vitro by the ram epididymis.

Protein synthesis has been investigated in different regions of the epididymis from normal rams, castrate rams, and castrate testosterone supplemented rams. Results show that there are few differences in the pattern of [35S]methionine-labelled proteins synthesized in different regions of the normal epididymis despite the variation in the morphology of the epithelial cells lining the duct. Three androgen-dependent proteins of molecular weights 24000, 64000 and approximately 200 000 were identified. Testosterone did not stimulate protein synthesis in the proximal caput epididymidis (region 1-3), suggesting that testicular fluid is important in maintaining the activity of epididymal cells in this area.

Androgens↗
PubMed1982

Contrast sensitivity as a function of exposure duration in the amblyopic visual system.

The spatiotemporal differences between the normal and amblyopic visual systems were investigated by measuring contrast sensitivity as a function of exposure duration for specific spatial frequencies of a sine-wave grating. At threshold, normal subjects had contrast-time reciprocity curves with slopes of approximately 0.7, indicating less than perfect temporal summation. The integration time (critical duration) varied as a function of spatial frequency with longer integration times for higher spatial frequencies (in agreement with previous studies). Amblyopic subjects had integration times and reciprocity slopes that were similar to the normals for low spatial frequencies; however, at high spatial frequencies there were significant differences. These results show that an amblyopic eye may either lack sustained neurons or alternately have sustained neurons with abnormal response characteristics.

Amblyopia↗
PubMed1982

Rescue and serotypic characterization of noncultivable human rotavirus by gene reassortment.

Thirty-three of 50 noncultivable human rotavirus strains from a variety of locations were successfully rescued by gene reassortment. The serotype of each of the 33 strains was investigated by a qualitative cytopathic effect neutralization assay. Nineteen strains resembled the previously characterized human rotavirus serotype Wa, whereas three strains were serologically related to the DS-1 strain. Eleven strains appeared to be serotypically distinct from the Wa and DS-1 strains and thus apparently represent one or more new human rotavirus serotypes.

Cytopathogenic Effect, Viral↗
PubMed1982

Homozygous alpha thalassemia/Hb G Philadelphia.

Microcytic red cells from a 70 year old Negro man with mild anemia contained only hemoglobin G-Philadelphia. Red cells from all of his children had low-normal MCV's, and contained 32-34 percent of the abnormal hemoglobin. Oxygen affinity of his blood and stability of his hemolysate were normal, suggesting that his mild anemia was not caused by the the abnormal hemoglobin. Restriction endonuclease analyses of DNA from the proband and his offspring showed that the alpha G-Philadelphia globin gene exists in only one copy per chromosome. The new gene was probably created by an unequal cross-over which deleted an alpha globin coding sequence (derived from one or both alpha globin genes), as well as some or all of the DNA sequence between those genes.

Aged↗