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Biomedical subjects

I M Evans

Publications and source records attributed to I M Evans.

At least 19 recordsLinked to original sources
PubMed1979

Effects of luteinizing hormone-releasing hormone on sexual arousal in normal men.

Six normal adult male subjects were administered either luteinizing hormone-releasing hormone (LRH, 500 micrograms, intramuscularly injected) or a saline placebo 10 min before a 40-min laboratory session in which they were exposed to erotic stimuli; subjects attended four such sessions, twice receiving LRH and twice the placebo in a balanced, double-blind, crossover design. Sexual arousal was inferred from degree of tumescence, with penile circumference measured by a mercury-in-rubber strain gauge. Heart rate was monitored continuously, and blood samples were taken periodically and assayed for serum luteinizing hormone (LH), follicle stimulating hormone (FSH), and testosterone (T). Rapidity of onset of erection, maximum degree of erection obtained, and overall levels of tumescence were consistently greater following LRH administration than following saline placebo; however, the differences were not statistically significant. The anticipated LH and FSH response to LRH was noted as well as a small increment in LH levels following erotic stimulation. No significant alteration in serum testosterone was observed within the time sampled. There were no significant correlations between hormonal data and any measurement of penile tumescence. In view of the results, further investigation of the behavioral effects of LRH appears justified.

Adult↗
PubMed1979

Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli.

When protein synthesis was blocked in temperature-sensitive deoxyribonucleic acid synthesis mutants of Escherichia coli at nonpermissive temperatures, it reduced the amount of apparent subsequent chain elongation to approximately half that observed in the mutants either at nonpermissive temperatures alone or when protein synthesis was blocked at the permissive temperature. Blocking protein synthesis at the nonpermissive temperatures for periods of 40 min caused the loss of ability to reinitiate deoxyribonucleic acid synthesis at the permissive temperature.

Amino Acids↗
PubMed1978

Familial medullary thyroid carcinoma.

Medullary thyroid carcinoma (M.C.T.) is a tumour of the calcitonin-secreting cells of the thyroid gland; it affects both lobes, has a variable malignant potential, and is often familial. Despite the availability of diagnostic plasma-calcitonin immunoassays, the condition is rarely considered in the initial assessment of a patient with a thyroid mass so that the is often disseminated by the time it is diagnosed, inadequate surgery is performed, and family members are not investigated. We studied 22 members of a family with M.C.T. and gave alcohol to provoke calcitonin secretion. 3 (excluding the index case) had raised basal calcitonin levels and the diagnosis of M.C.T. was confirmed at operation; their calcitonin levels became undetectable after total thyroidectomy. 3 others had detectable levels after alcohol stimulation and are being re-screened at regular intervals.

Adolescent↗
PubMed1978

Personality, sexuality, and demographic differences between volunteers and nonvolunteers for a laboratory study of male sexual behavior.

Personality, sexuality, and demographic differences were examined in volunteers and nonvolunteers for a laboratory study of male sexual arousal. Subjects were 108 participants in a questionnaire study entitled "Personality and Sexuality", who were then asked to volunteer for a second study which necessitated watching sexually explicit films, being partially undressed in an experimental chamber, and having penile diameter measured via a strain gauge device. Volunteers for the second study were found to be less guilty, less sexually fearful, more sexually experienced, and older than nonvolunteers. Volunteers also reported a higher incidence of past erectile difficulties and tended to be White or of mixed racial heritage, as opposed to being Oriental. Other personality variables did not discriminate between the two groups. The results indicate that future research in human sexuality using the laboratory analytic method must impose strict limits on generalization from the research data.

Adolescent↗
PubMed1977

Feedback regulation of vitamin D metabolism by 1,25-dihydroxycholecalciferol.

Many factors influence the production of 1,25(OH)2D3 (1,25-dihydroxycholecalciferol) by the kidney. One important factor seems to be feedback regulation by 1,25(OH)2D3 itself. Administration of 1,25(OH)2D3 to vitamin D-deficient chicks abolishes renal 25(OH)D3(25-hydroxycholecalciferol)1-hydroxylase activity and induces the appearance of 25(OH)D3 24-hydroxylase activity. It is likely that these effects are mediated via a nuclear effect, as they are prevented by pretreatment with actinomycin D and alpha-amanitin. Further, 1,25(OH)2D3 has a marked effect on gene transcription in the kidney cell, as assessed by measurement of RNA polymerase activities. RNA polymerase I and II activities are 80-90% inhibited by 12.5nmol of 1,25(OH)2D3 within 30min of subcutaneous administration, indicating an immediate and massive decrease in total gene transcription. By 4h RNA polymerase II activity has returned to control values, but RNA polymerase I activity is markedly enhanced. These results are consistent with the view that regulation of cholecalciferol metabolism in the kidney is associated with an effect of the active metabolite on the kidney nucleus.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1977

Biochemical markers in bronchial carcinoma.

A total of 107 patients with bronchial carcinoma have been studied for the presence of potential circulating tumour markers which might be used as indicators of recurrence after primary treatment. Plasma carcinoembryonic antigen (CEA) levels were estimated in every patient and, after a preliminary hormone screening study, plasma calcitonin (CT) and parathyroid hormone (PTH) levels were assayed in 66 patients. Oat-cell tumours proved to be of particular interest in that CEA levels greater than 40 microgram/l were measured (initially or subsequently) in 40.6 percent and CT levels were elevated in 75 percent. Longitudinal studies point towards the possible use of elevated marker levels as guides to therapy when all other features of recurrent disease are lacking. It is clear that no ideal tumour marker exists for bronchial carcinoma but in an individual case an abnormal level of one or more marker substances may provide a valuable aid to treatment.

Bronchial Neoplasms↗
PubMed1977

Vitamin D.

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Bone and Bones↗