Search PubMed⌕ Search

Biomedical subjects

J G Lewis

Publications and source records attributed to J G Lewis.

107 records · Page 6Linked to original sources
PubMed1978

A possible ACTH secreting tumour of the pituitary developing in a conventionally treated case of Addison's disease.

A patient with Addison's disease, treated with conventional corticosteroid therapy, developed endocrine and radiological features suggestive of an ACTH secreting pituitary tumour. The negative feedback control of ACTH secretion by the inhibitory effect of hydrocortisone was shown to be preserved although attenuated. Retiming and alteration of corticosteroid therapy reinforced this feedback control, without the need for supraphysiological amounts of steroid, and resulted in the regression of the endocrine disorder.

Addison Disease↗
PubMed1977

The hormone response to a synthetic androgen (mesterolone) in oligospermia.

Forty subfertile men with oligospermia were treated with a synthetic androgen (Mesterolone). The effect of the drug was evaluated by measuring serum testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and analysing the semen before and after treatment. The results demonstrated that in twenty-three patients treated for 6-9 months there was a significant decrease in serum testosterone (P less than 0.01); the means +/- SEM before and after treatment were 17.05 +/- 0.95 and 14.7 +/- 0.95 (nmol/l serum) respectively. There was a pronounced increase in serum LH (P less than 0.01), the values being 2.73 +/- 0.26 and 3.61 +/- 0.3 (u/l) respectively. However, no significant difference was found in serum FSH before and after treatment. The sperm concentration showed a variable response to treatment. In twenty-one patients there was either no change or worsening in the sperm concentration, whereas in nineteen patients an improvement was observed. The analysis of variance of sperm concentration and motility for the periods before and after treatment, for all the patients, showed no significant difference in the sperm concentration F1.145 = 2.82 (P=0.1).

Dihydrotestosterone↗
PubMed1977

Serum dihydrotestosterone in patients with benign prostatic hypertrophy.

Serum dihydrotestosterone (DHT) and testosterone were measured by radioimmunoassay in 24 normal men aged 60 to 80 years and in 25 patients with benign prostatic hypertrophy in the same age range. There was a significant increase in the level of dihydrotestosterone in patients with prostatic hypertrophy but no significant difference was found between the testosterone levels of the 2 groups. The scatter of the individual values for DHT indicated that this measurement has little practical clinical application in the diagnosis of prostatic hypertrophy. It is suggested that the increase in DHT may be due, at least in part, to a prostatic contribution to the circulating level and the relevance of this observation in relation to the aetiology of benign prostatic hypertrophy is discussed.

Aged↗
PubMed1977

Androgen concentrations in prostate and serum of the male and female Praomys (Mastomys) natalensis.

The levels of androgens in the male prostate, seminal vesicles, and serum, as well as in the female prostate and serum, were measured in the rodent Praomys (Mastomys) natalensis. Measurements were made in different age groups of both males and females using a sensitive radioimmunoassay. The results showed that the values for serum testosterone were 10 times greater in the male than the female. The concentration of serum dihydrotestosterone in the male was approximately one-tenth of the concentration of testosterone. The recovery of dihydrotestosterone from the prostate in the female and seminal vesicle in the male was low and these values were not considered. The concentrations of testosterone and dihydrotestosterone in the male prostate were 8.3 +/- 0.5 and 20.0 +/- 2.4 ng per g of wet tissue, respectively. The concentration of testosterone in the female prostate, 7.1 +/- 0.5 ng per g of wet tissue, was similar to that in the male. These studies have shown that the female Mastomys has a prostate which exists in a low androgen environment; it is suggested that this could be used as an experimental model for studying hormonal effects on the prostate.

Androgens↗
PubMed1976

Serum 5alpha-dihydrotestosterone and testosterone changes with age in man.

Serum 5alpha-dihydrotestosterone (DHT) and testosterone (T) were measured in 98 normal adult men aged between 20-80 years, separating T and DHT by thin layer chromatography and using a sensitive and reliable radio-immunoassay. In three age groups between 20-40, 40-60 and 60-80, the means +/- SEM for serum DHT were 84 +/- 4, 79 +/- 3 and 67 +/- 3 (ng/100 ml) respectively. The corresponding values for testosterone were 559 +/- 25, 491 +/- 25 and 475 +/- 28 (ng/100 ml). A significant decrease was observed in the DHT level of the 60-80 years age group compared to either the 20-40 (P less than 0.01) or the 40-60 (P less than 0.02) age groups. There was a moderate decline in the testosterone level of the 60-80 years age group compared to 20-40 years (P less than 0.05) but there were no significant changes in the testosterone levels between other groups.

Adult↗
PubMed1975

Serum testosterone and dihydrotestosterone changes with age in rat.

Serum testosterone (T) and 5alpha-dihydrotestosterone (DHT) were measured in young, adult and old Albino Wistar male rats using a sensitive and reliable radioimmunoassay, after separating T from DHT by thin layer chromatography. The mean plus or minus S.E.M. for T in young, adult and old rats were 62 plus or minus 11, 250 plus or minus 27 and 125 plus or minus 25 (ng/100 ml) respectively. Serum T was increased in adults (P less than 0.001) and decreased in old rats (P less than 0.01). The mean plus or minus S.E.M. for serum DHT was 8 plus or minus 2, 19 plus or minus 2 and 17 plus or minus 1 (ng/100 ml) for young, adult and old rats respectively. DHT was increased in adults (P less than 0.001), but did not change in old rats.

Aging↗
PubMedDate not supplied

Plasma androsterone/epiandrosterone sulfates as markers of 5 alpha-reductase activity: effect of finasteride in normal men.

Plasma androsterone/epiandrosterone sulfates, dehydroepiandrosterone sulfate, dihydrotestosterone, testosterone, androstenedione, and cortisol were measured in three normal adult men before and following finasteride administration (5 mg/day). Plasma androsterone/epiandrosterone sulfates and dihydrotestosterone declined in parallel to 50% of basal levels with little change in either dehydroepiandrosterone sulfate, cortisol, or androstenedione. The results suggest that the direct measurement of plasma androsterone/epiandrosterone sulfates by enzyme-linked immunosorbent assay provide similar information to plasma dihydrotestosterone and therefore provide a simple alternative for the assessment of 5 alpha-reductase activity.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMedDate not supplied

Central nervous system serotonin function and cardiovascular responses to stress.

OBJECTIVE: The objective of this study was to evaluate the impact of indices of central nervous system (CNS) serotonin function on cardiovascular reactivity to mental stress. METHODS: Lumbar puncture was performed on 54 healthy volunteers to obtain cerebrospinal fluid (CSF) for determination of 5-hydroxyindoleacetic acid (5HIAA) levels. Genotypes were determined with respect to a functional polymorphism of the serotonin transporter gene promoter region (5HTTLPR). Subjects then underwent mental stress testing. RESULTS: Persons with one or two long (l) 5HTTLPR alleles had CSF levels of the major serotonin metabolite, 5HIAA, that were 50% higher than those of persons with the s/s 5HTTLPR genotype. Persons with one or two l alleles or higher CSF 5HIAA levels also exhibited greater blood pressure and heart rate responses to a mental stress protocol. CONCLUSIONS: These findings suggest the 5HTTLPR polymorphism affects CNS serotonin function, and they are consistent with the general hypothesis that CNS serotonin function is involved in the regulation of potentially health-damaging biobehavioral characteristics. In particular, the l allele could contribute, through its association with increased cardiovascular reactivity to stress, to increased risk of cardiovascular disease.

Adult↗