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Biomedical subjects

S R Plymate

Publications and source records attributed to S R Plymate.

12 recordsLinked to original sources
PubMed1992

The effects of sex hormone binding globulin (SHBG) on testosterone transport into the cerebrospinal fluid.

The movement of testosterone (T) from blood across the blood-brain barrier (BBB) is thought to reflect the combined effects of T's lipid solubility and the presence of circulating binding proteins for T such as albumin or sex hormone binding globulin (SHBG). Since the adult rat lacks a circulating specific high affinity sex steroid binding protein, examination of the disappearance from serum and uptake into cerebrospinal fluid (CSF) of [3H]T before and after SHBG or albumin infusion should provide insight into the function of these two proteins with respect T transport. Three groups of adult male Sprague-Dawley rats were cannulated at the femoral vein and cisterna magna. In a control group (n = 8), [3H]T was given as an intravenous bolus beginning at time zero; multiple serum and CSF collections were assayed for counts per min (cpm) during the subsequent 45 min. Data from these animals were then compared to those seen in animals that received either purified human SHBG (hSHBG) (n = 7) or human albumin (hALB) (n = 6) 10 min prior to the [3H]T infusion. High performance liquid chromatography was used to monitor the metabolic fate of the steroid infusate at the end of each study period. Infusion of hSHBG increased serum concentrations from undetectable to 93.8 nM/l (mean +/- SEM, n = 6). Administration of hALB significantly increased (25.0 +/- 1.2 g/l at baseline, 33.4 +/- 1.6 g/l post-infusion, mean +/- SEM, P less than 0.03, n = 5) the circulating albumin concentration. Comparison of data from each group of animals demonstrated that (1) following an i.v. injection of radiolabeled T, the initial decline in serum [3H]T was significantly reduced (P less than 0.03) in the presence of hSHBG, (2) hALB did not affect the movement of [3H]T out of serum, (3) the time to peak appearance of [3H]T in the CSF was significantly delayed (P less than 0.02) by the presence of circulating hSHBG, and (4) the net quantity of [3H]T found in the cSF under steady-state conditions was not affected by serum SHBG or albumin levels. This study demonstrates that high-affinity steroid binding proteins do modulate the transport of sex steroids across the BBB. Specifically, SHBG delays the clearance of T from serum and slows the rate of T uptake into the CSF during non-equilibrium conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1992

Relationship of serum inhibin levels to serum follicle stimulating hormone and sperm production in normal men and men with varicoceles.

The purpose of this study was to examine the relationships between serum inhibin levels as measured by RIA and serum FSH and sperm concentration. Three groups of men were used for this study: group I, normal fertile men (n = 67); group II, fertile men with a varicocele (n = 57); and group III, infertile men with a varicocele (n = 21). There were no differences in mean serum inhibin levels between the three groups. The two groups of men with varicoceles exhibited higher serum FSH levels and FSH responses to GnRH than the normal men. Sperm counts in both groups II and III were significantly lower than group I. In the normal men there was an inverse correlation between baseline serum inhibin and serum FSH levels and GnRH stimulated FSH levels, r = -0.415 and 0.422, P less than 0.005, respectively. Furthermore, the normal men exhibited a positive correlation between serum inhibin measurements and sperm concentration and testicular volume, r = 0.35 and 0.26, P less than 0.01 and less than 0.05, respectively. In neither group of men with a varicocele were these relationships found. These data demonstrate that serum inhibin does correlate with FSH in a negative fashion, when the reproductive system is normal, as would be expected for a negative feedback factor. Finally, the relationship of serum inhibin levels to testicular size and sperm count in the normal men suggests that serum inhibin levels reflect to some extent the integrity of seminiferous tubule function.

Follicle Stimulating Hormone↗
PubMed1991

Psychological and serum homovanillic acid changes in men administered androgenic steroids.

We report a difference in the response of serum homovanillic acid (HVA) and in the performance of some psychological tasks before and after the administration of testosterone enanthate (TE, 100 or 300 mg/wk) or nandrolone decanoate (ND, 100 or 300 mg/wk) for 6 wk to healthy men. Serum HVA was significantly increased in both the low- and high-dose ND groups, from 8.4 +/- 1.0 and 8.7 +/- 0.5 pmol/ml (mean +/- SE) to 11.6 +/- 1.7 and 10.7 +/- 1.1 pmol/ml respectively. No significant changes in HVA were observed for the groups administered TE, nor in 5-HIAA for any of the groups. The influence of ND on the dopaminergic system, which is reflected in increased serum HVA, appears to be independent from the psychological effects which were produced by both androgens. The only change in psychomotor test performance was an improvement in the first trial of a pegboard task. All subjects except those receiving ND (100 mg/wk) were significantly more optimistic in the prediction of their own performance for all nondominant hand tasks (pegboard and finger tapping). The "hostility" and "resentment and aggression" subscales of the MMPI increased significantly in all groups, more so in the high-dose groups.

Adult↗
PubMed1991

Comparison of the effects of high dose testosterone and 19-nortestosterone to a replacement dose of testosterone on strength and body composition in normal men.

We examined the extent to which supraphysiological doses of androgen can modify body composition and strength in normally virilized men. In doubly blind tests, 30 healthy young men received testosterone enanthate (TE) or 19-nortestosterone decanoate (ND), at 100 mg/wk or 300 mg/wk for 6 weeks. The TE-100 mg/wk group served as replacement dose comparison, maintaining pretreatment serum testosterone levels, while keeping all subjects blinded to treatment, particularly through reduction in testicular volumes. Isokinetic strength measurements were made for the biceps brachii and quadriceps femoris muscle groups before treatment and 2-3 days after the 6th injection. Small improvements were noted in all groups but the changes were highly variable; a trend to greater and more consistent strength gain occurred in the TE-300 mg/wk group. There was no change in weight for TE-100 mg/wk but an average gain of 3 kg in each of the other groups. No changes in 4 skinfold thicknesses or in estimated percent body fat were observed. Of 15 circumferences, significant increases were observed only for men receiving TE-300 mg/wk (shoulders) and ND-300 mg/wk (shoulders and chest). The data suggest that high dose androgens increase body mass and may increase strength in normal men but, except for a consistent weight gain with greater than replacement doses, the detectable changes were highly variable and relatively small, especially in comparison to the significant alterations which were observed for other markers of androgen action.

Adult↗
PubMed1991

Effects of sex hormone binding globulin (SHBG) on human prostatic carcinoma.

The purpose of this study was to determine what effects sex hormone binding globulin (SHBG) might have on the growth and steroid content of human prostate carcinoma. Two human prostate carcinoma cell lines were used for this study, ALVA-41 and ALVA-101. The first part of the study was to determine the effect of SHBG or albumin on the uptake of [3H]DHT in the cells. In this experiment both SHBG and albumin inhibits the uptake of [3H]DHT into each of the cell lines when studied in vitro. The degree of inhibition was dependent on the binding capacity of the protein. When [3H]thymidine uptake was measured in each of the cell lines following either the addition of SHBG or albumin to the culture media, an increase in uptake and presumably DNA synthesis was noted in the ALVA-41 and ALVA-101 cells for SHBG additions but not for albumin. Further, this stimulation was increased when testosterone was added to the media, however, [3H]thymidine uptake was decreased by high concentrations of dihydrotestosterone (DHT) or if the SHBG was saturated with DHT prior to being added to the media. The cells also demonstrate high affinity cell membrane receptors for SHBG. Finally, using a 3', 550 bp cDNA or SHBG, 1.9 and 2.8 kb mRNAs were detected on Northern analysis of the ALVA-101 and ALVA-41 cells. These data indicate SHBG can inhibit uptake of steroids into the prostate, but also it may act as a stimulus for growth through a SHBG cell surface receptor. In addition, the growth effect may be through an autocrine effect from SHBG or a SHBG-related peptide.

Biological Transport↗
PubMed1991

A direct effect of hyperinsulinemia on serum sex hormone-binding globulin levels in obese women with the polycystic ovary syndrome.

To determine whether hyperinsulinemia can directly reduce serum sex hormone-binding globulin (SHBG) levels in obese women with the polycystic ovary syndrome, six obese women with this disorder were studied. Before study, ovarian steroid production was suppressed in each woman by the administration of 7.5 mg of a long-acting GnRH agonist, leuprolide depot, im, on days -56, -28, and 0. This resulted in substantial reductions in serum concentrations of testosterone (from 1.72 +/- 0.29 nmol/L on day -56 to 0.32 +/- 0.09 nmol/L on day 0), non-SHBG-bound testosterone (from 104 +/- 16 pmol/L on day -56 to 19 +/- 5 pmol/L on day 0), androstenedione (from 7.25 +/- 1.65 nmol/L on day -56 to 2.78 +/- 0.94 nmol/L on day 0), estrone (from 371 +/- 71 pmol/L on day -56 to 156 +/- 29 pmol/L on day 0), estradiol (from 235 +/- 26 pmol/L on day -56 to 90 +/- 24 pmol/L on day 0), and progesterone (from 0.28 +/- 0.12 nmol/L on day -56 to 0.08 +/- 0.02 nmol/L on day 0). Serum SHBG levels, however, did not change (18.8 +/- 2.8 nmol/L on day -56 vs. 17.8 +/- 2.6 nmol/L on day 0). While continuing leuprolide treatment, the women were administered oral diazoxide (300 mg/day) for 10 days to suppress serum insulin levels. Diazoxide treatment resulted in suppressed insulin release during a 100-g oral glucose tolerance test (insulin area under the curve, 262 +/- 55 nmol/min.L on day 0 vs. 102 +/- 33 nmol/min.L on day 10; P less than 0.05) and deterioration of glucose tolerance. Serum testosterone, androstenedione, estrone, estradiol, and progesterone levels did not change during combined diazoxide and leuprolide treatment. In contrast, serum SHBG levels rose by 32% from 17.8 +/- 2.6 nmol/L on day 0 to 23.5 +/- 2.0 nmol/L on day 10 (P less than 0.003). Due primarily to the rise in serum SHBG levels, serum non-SHBG-bound testosterone levels fell by 43% from 19 +/- 5 pmol/L on day 0 to 11 +/- 4 pmol/L on day 10 (P = 0.05). These observations suggest that hyperinsulinemia directly reduces serum SHBG levels in obese women with the polycystic ovary syndrome independently of any effect on serum sex steroids.

Adult↗
PubMed1976

The association of D-group chromosomal translocations and defective spermatogenesis.

D-group chromosome translocations have been associated in isolated cases with infertility in males. In this study, we demonstrated the effect of a translocated D-group chromosome on spermatogenesis as it had segregated among three male members of one family. Although the father, who carried the translocation, was obviously fertile, the effects of the translocations on his sperm were noted in the morphologic examination. This study demonstrates the need for more careful evaluation of patients with chromosomal abnormalities for effects on spermatogenesis. Furthermore, it shows the possibility of autosomal chromosomal influences on testicular function.

Adult↗
PubMed1975

Prevalence of circulating HL-A lymphocytotoxic antibodies in men after vasectomy.

Thirty-two men undergoing vasectomy were studied for one year to determine presence of HL-A antibodies after surgery. Blood samples were taken prior to vasectomy and at three, six, nine, and 12 months following surgery. Twenty-six men showed no increase in antibody activity during the study when their sera were matched against a 25-member typed lymphocyte donor panel. Sera of two men showed a definite increase in positive reactions, six to 12 months after surgery. The sera of four men showed slight increases in reactivity between three and 12 months after vasectomy. The serum of one man showed a single positive reaction against his own lymphocytes three months after surgery, but no positive reactivity against the lymphocyte donor panel. These studies suggest that HL-A antibodies are not regularly formed as a result of standard vasectomy procedures, but that further long-term evaluation of vasectomized patients may be needed to make definite conclusions.

HLA Antigens↗