Effect of dietary copper on selenium toxicity in Fischer 344 rats.

The purpose of this study was to investigate the ameliorating effects of dietary copper supplementation on selenium toxicity. Nine groups (n = 6) of weanling Fischer 344 female rats were randomly assigned to treatment groups and fed diets containing nontoxic levels of copper as CuCl2 and/or selenium as selenite or selenocystamine. Weight gain, liver and spleen weights, plasma lipid peroxidation, and liver selenium and copper content were analyzed after the 6-wk treatment period. Concentrations of up to 10 times the daily lethal dose of dietary selenium were well tolerated in rats supplemented with dietary copper. As the dietary level of selenium was increased, the ratio of selenium to copper measured in the liver decreased. In the groups of rats in which dietary copper supplementation was absent and dietary selenium was supplemented, copper stores in the liver remained unchanged from control values. Copper's protective effects from dietary selenium toxicity may come from the formation of a copper-selenide complex that renders both selenium and copper metabolically unavailable and nontoxic.

Severe dietary magnesium deficiency does not alter levels and function of myocardial Gs alpha and Gi alpha.

Magnesium ions (Mg2+) play a crucial role in the activation and synthesis of guanine nucleotide-binding proteins (G proteins). However, there is no information about the influence of in vivo magnesium deficiency on the function and levels of G proteins. This study was done to investigate whether dietary magnesium deficiency alters function and levels of the two major myocardial G proteins, Gi alpha and Gs alpha. Severe hypomagnesemia and a significant reduction of myocardial magnesium occurred in rats fed a magnesium-deficient diet for 6 wk vs. rats fed a normal-magnesium diet (control). The magnesium-deficient rats developed focal myocardial lesions but their cardiac function was not impaired. Myocardial immunodetectable Gs alpha and Gi alpha levels of magnesium-deficient rats did not differ from control (Gs alpha: 2.39 +/- 0.52 vs. 2.76 +/- 0.72 arbitrary units/microgram protein, P > 0.05; Gi alpha: 1.60 +/- 0.52 vs. 1.89 +/- 0.30 arbitrary units/microgram protein, P > 0.05). Similarly, the function of Gs alpha and Gi alpha estimated by basal and ligand-stimulated adenylyl cyclase activity was not significantly different between the two groups of animals. The results show that dietary-derived magnesium deficiency sufficient to produce severe hypomagnesemia does not produce any significant change in levels or function of myocardial G proteins.

Dietary magnesium deficiency increases Gi alpha levels in the rat heart after myocardial infarction.

OBJECTIVE: Magnesium (Mg) is crucial for the function of G proteins which play important roles in mediating the inotropic effects of beta adrenergic agonists in the heart and are altered in heart failure. This study was performed to determine whether or not dietary Mg deficiency alters functional activity and levels of the two major ventricular G proteins, Gi alpha and Gs alpha in the heart after myocardial infarction (MI). METHODS: Six week old rats were fed an Mg adequate or deficient diet for 6 weeks. At the end of week 3, MI was induced by coronary artery ligation. A sham operation was performed as control. After surgery, surviving animals were maintained on their assigned diets for another 3 weeks. Then, cardiac function was measured, plasma and tissue were collected. RESULTS: Severe hypomagnesemia and increased plasma catecholamine level were observed in all animals fed the Mg deficient diet. A significant reduction of myocardial Mg concentration accompanied by elevated plasma and myocardial calcium concentrations was observed in MI animals with existing Mg deficiency vs. animals fed the Mg adequate diet. Cardiac function was impaired in MI rats and further reduced in MI rats with existing Mg deficiency. Gi alpha level was not altered by either Mg deficiency or MI alone, but was dramatically elevated in animals with combined Mg deficiency and MI (9.9 +/- 0.7 arbitrary unit.mg-1 protein) as compared to MI alone (5.8 +/- 0.6, P < 0.05) and Mg deficiency alone (6.1 +/- 0.8, P < 0.05). Gs alpha level did not differ between groups. GppNHp-, but not fluoride-stimulated adenylyl cyclase activity was slightly reduced in MI animals with existing Mg deficiency. CONCLUSION: The findings suggest that dietary Mg deficiency increases the expression of Gi alpha in the heart after MI, while levels and function of Gs alpha are not compromised during dietary Mg deficiency either with or without MI.

Suppression of human spermatogenesis by testosterone implants.

Hormonally induced azoospermia is an effective, reversible form of male contraception; however, some men treated with weekly im testosterone enanthate (TE) injections fail to become azoospermic. As weekly injections cause widely fluctuating and supraphysiological testosterone levels, we tested the hypothesis that more stable, physiological testosterone levels would consistently produce azoospermia. Using a depot testosterone formulation which provides stable, physiological range testosterone levels for up to 6 months, we studied nine men before and after insertion of six 200 mg testosterone implants under the abdominal wall skin and compared the results with 38 men treated in a previous study with weekly im injections of 200 mg TE. Testosterone implants suppressed sperm output to near-azoospermia between the second to fourth postimplant months returning to normal by the sixth postimplant month. The fall in sperm output at the first month was greater after testosterone implants than TE injections (58% vs. 17%, P = 0.011) but similar proportions of men became azoospermic (5/9 vs. 25/38) or severely oligozoospermic (< 1 million/ml; 9/9 vs. 37/38). Plasma testosterone and estradiol levels remained mostly within the eugonadal range after implants but were markedly supraphysiological during TE injections. Both treatments suppressed immunoreactive LH and FSH to undetectable levels by ultrasensitive fluoroimmunoassay. Sex hormone-binding globulin levels were decreased and PRL levels increased by TE injections but neither was changed by testosterone implants. Prostate-specific antigen demonstrated a small rise of marginal significance (P = 0.065) after testosterone implants. Fewer men experienced acne after implants (0/9 vs. 25/38, p = 0.0004). Therefore a depot testosterone preparation with quasi-zero-order release demonstrates higher dose efficiency with similar (but not uniform) efficacy at inducing azoospermia but may cause fewer androgenic side-effects than weekly TE injections.

PIP: In Sydney, Australia, researchers analyzed data on 9 healthy men aged 21-50 to determine the effects of 6 long acting depot testosterone (200 mg) implants under the abdominal wall on spermatogenesis. They also compared these data with retrospective data on 38 healthy men who had received weekly testosterone (200 mg) injections to determine whether steady-state testosterone levels within the physiological range might achieve azoospermia uniformly in fertile men. The implants dramatically decreased sperm output to near 0 levels between the 2nd and 4th month after implantation. By 6 months postimplant the sperm density had returned to normal. The injections produced similar reductions in sperm output, but the rate of decrease was significantly greater at the first month in men with the implants (58% vs. 17%; p = 0.011). Similar proportions of men in the implant group and the injection group had achieved azoospermia (56% vs. 66%) or severe oligospermia (1 million sperm/ml; 100% vs. 97%). Plasma testosterone and estradiol levels largely stayed within the eugonadal range after insertion of implants. They were considerably supraphysiological during testosterone injections, however. Both testosterone implants and testosterone injections inhibited immunoreactive luteinizing hormone and follicle stimulating hormone (p 0.05). Testosterone injections reduced sex hormone binding globulin levels but increased PRL levels (p 0.05). Testosterone implants increased prostate-specific antigen by about 20% (p = 0.065). Acne was more prevalent after injections than after implants (0/9 vs. 25/38; p = 0.0004). Both testosterone treatments had biochemical effects of similar magnitude. These findings suggest that the testosterone implants with quasi-zero-order release have a higher dose efficiency than the injections with similar efficacy at achieving azoospermia, but may result in fewer androgenic side effects than the injections.

Effect of selenium compounds and thiols on human mammary tumor cells.

The effect on cell viability and growth rate of sodium selenite, selenocystine, sodium selenate, and selenomethionine at selenium concentrations of 6.25 and 12.5 uM was studied in vitro on cells of the human mammary tumor cell line HTB123/DU4475. Selenite and selenocystine affected both cell viability and growth rate of the tumor cells at these selenium concentrations. Selenite and selenocystine decreased intracellular glutathione concentrations, but did not affect tumor cell glutathione peroxidase activity. After six days of exposure to either selenate or selenomethionine, the viability of tumor cells remained stable, but cell growth, as measured by numbers of cells, was retarded. Neither selenate nor selenomethionine produced changes in concentrations of intracellular glutathione. The toxic effect of selenite on tumor cells was enhanced by addition of 0.25 mM glutathione to the growth medium. Preincubation of the tumor cells with 62.5 uM buthionine sulfoximine decreased cellular glutathione to 15% of controls at 24 h and enhanced the toxicity of selenite toward the tumor cells. Glutathione, 2-mercaptoethanol, and L-cysteine were all toxic to the tumor cells in a dose-dependent manner.

Effect of dietary selenium and magnesium on human mammary tumor growth in athymic nude mice.

The effect of dietary selenium (Se) supplementation and low dietary magnesium (Mg) on growth of cells of the human mammary tumor cell line (HTB123/DU4475) and the tissue glutathione (GSH) content in female athymic nude mice was studied. Sixty three- to four-week-old female athymic nude mice were randomly divided into six dietary groups of 10 animals. The mice were fed a modified AIN-76A diet with two levels of Mg (100 and 665 mg/kg) and three levels of Se (0.04, 0.2, and 4.0 mg/kg). At the fourth week of dietary treatment, mice were subcutaneously inoculated with 2.5 x 10(6) viable tumor cells on the dorsal lumbar region and then fed their respective diets for another four weeks. Dietary Se supplementation had no significant effect on tumor growth or tissue GSH content. Low dietary Mg limited both tumor growth and tissue GSH synthesis but raised Mg and GSH levels in tumor tissues. The growth of mice fed the diet containing 100 mg/kg Mg and 4.0 mg/kg Se was significantly retarded. This study demonstrated that neither Se deficiency nor Se supplementation had any effect on mammary tumor growth or tissue GSH content in athymic nude mice. Low dietary Mg did retard tumor growth and inhibited GSH synthesis. Low dietary Mg also resulted in an apparent increase in Se toxicity in these animals.

Pharmacokinetics and pharmacodynamics of testosterone pellets in man.

We studied the pharmacokinetics and pharmacodynamics of sc implanted pellets of fused crystalline testosterone. Three different regimens (6 x 100 mg, 6 x 200 mg; and 3 x 200 mg) were compared in a prospective, cross-over clinical trial in which androgen deficient men were administered the three-dose combinations in a randomized starting order at intervals of at least 6 months. Plasma free and total testosterone, sex hormone-binding globulin, LH, and FSH were measured before and at monthly intervals for at least 6 months after 111 pellet implantation in 43 men with hypergonadotropic (n = 22) or hypogonadotropic (n = 21) hypogonadism. Total and free testosterone levels peaked at the first month and were maintained at physiological levels for 4 to 5 (600 mg doses) or 6 (1200 mg dose) months after a single implantation. Absorption of testosterone from 100 mg and 200 mg pellets closely approximated zero-order throughout the effective life of the pellets and exhibited a half-duration of 2.5 months. The estimated rate of release of testosterone was 1.5 (95% confidence limits 1.3-1.6) mg/day.200 mg pellet as determined from direct measurement of residue in pellets recovered after extrusion and confirmed independently from percent absorbed-time plots. The bioavailability of testosterone was virtually complete and the time course was predictable from the total implant dose and, to a lesser extent, total initial surface areas of pellets. Despite wide fluctuations in testosterone, SHBG levels were not changed during 6 months. In men with hypergonadotropic hypogonadism, both LH and FSH levels were uniformly and markedly suppressed by increased testosterone after pellet implants. LH and FSH were highly correlated with each other (r = 0.87) and inversely with total (r = 0.47 and 0.45, respectively) and free (r = 0.46 and 0.47) testosterone levels. Nadir LH levels occurred at 1-3 months (600 mg) and 1-4 months (1200 mg) reaching levels comparable with eugonadal controls. In contrast nadir FSH levels occurred at similar times but remained elevated compared with eugonadal controls. We conclude that fused pellets of crystalline testosterone provides very satisfactory depot androgen replacement exhibiting many desirable features for androgen replacement.

Randomized clinical trial of testosterone replacement therapy in hypogonadal men.

We have compared the pharmacokinetics and pharmacodynamics of the three commonly used testosterone formulations in a prospective, randomized cross-over clinical trial. Plasma free and total testosterone and their ratio (proportion of unbound testosterone), sex hormone-binding globulin (SHBG), oestradiol, LH and FSH were measured in 15 hypogonadal men (nine hyper- and six hypogonadotrophic) who underwent, in a randomized sequence, three treatment periods each separated by an intervening washout period. The treatments were: (i) intramuscular injection of 250 mg mixed testosterone esters at 2-weekly intervals, (ii) oral testosterone undecanoate 120 mg bd, and (iii) subcutaneous testosterone pellets (6 x 100 mg). Pellet implantation gave the most prolonged effect with free and total testosterone levels being elevated for up to 4 months. This was accompanied by prompt and sustained suppression of plasma LH and FSH, an increase in plasma levels of oestradiol but no change in SHBG levels. In contrast, intramuscular injections induced marked but reproducible week-to-week fluctuations in free and total testosterone, which resulted in a small decrease in plasma SHBG levels, less marked suppression of LH and FSH and a smaller increase in plasma levels of oestradiol. Oral testosterone undecanoate produced the most variable plasma levels of free and total testosterone with a peak in the first treatment week and a fall thereafter and, despite maintenance of testosterone levels within the physiological range, there was no significant suppression of plasma levels of LH and FSH, and oestradiol levels were unchanged but levels of SHBG and total cholesterol were decreased. Free testosterone levels were increased disproportionately during testosterone treatment as the proportion of unbound testosterone was increased by all three treatments. All three testosterone preparations lowered plasma levels of urea and all were without biochemical or haematological toxicity. Reported sexual function was better maintained and side-effects were fewer with parenteral compared with oral treatments. The marked decrease in SHBG and cholesterol levels during oral testosterone undecanoate, when compared with parenteral treatments, occurred despite lesser androgenic effects (suppression of gonadotrophin levels and reported sexual function), which suggests that the liver is exposed to excessive androgenic load via the portal vein during oral treatment with testosterone esters. It is concluded that testosterone pellets give the closest approximation to zero-order (steady-state) delivery conditions for up to 4 months after a single insertion.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacodynamics of gonadotropin-releasing hormone (GnRH). II. Pattern of GnRH delivery alters pituitary luteinizing hormone secretion in women.

The pulse frequency, amplitude, and mode of administration of GnRH all influence gonadotropin secretion and, ultimately, pituitary-gonadal function. We studied plasma LH responses to repetitive iv administration of GnRH given hourly for 5 h as a 2-microgram rapid (less than 15 s) bolus dose or a 2-microgram dose infused for 15 min of each hour in seven women deficient in endogenous GnRH and sex steroids. Plasma LH levels, measured at 10-min intervals throughout the 5-h period, rose more briskly (pattern X time course interactions: F = 3.33; P less than 0.0001) to higher levels overall (F = 11.7; P = 0.014) after rapid bolus GnRH administration than after GnRH infusion. Plasma FSH levels increased during both modes of delivery, with higher responses to rapid bolus GnRH administration (P = 0.005). Plasma estradiol levels did not change during either 5-h study. We conclude that the pattern of delivery of GnRH is a determinant of pituitary LH and FSH secretion in untreated hypogonadotropic women, and therefore, that alterations in the GnRH wave form and/or peak plasma GnRH concentrations consequent upon different rates of GnRH entry into the blood-stream may explain the different responses that occur when GnRH is given by different routes.

Vitamin E, vitamin B-6, vitamin B-12, and folate status of gastric bypass surgery patients.

The vitamin E, vitamin B-6, vitamin B-12, and folate status of 22 gastric bypass subjects aged 23 to 60 years was evaluated before surgery and at 6 and 12 months after surgery. Before surgery, 77% of subjects had adequate plasma vitamin E levels; 36%, adequate plasma pyridoxal phosphate levels; 100%, adequate plasma vitamin B-12 levels; and 45%, adequate plasma folate levels. The food intake of all subjects was sharply reduced after surgery. After surgery, subjects were classified into three vitamin supplement groups on the basis of average daily vitamin supplement intake. Subjects taking higher levels of supplements containing the vitamins in question had significantly higher plasma concentrations of the vitamins than those taking low or moderate levels. The mean plasma vitamin values in the moderate supplement group were indicative of adequate status for all vitamins, but plasma vitamin B-12 levels at 12 months post-surgery were significantly lower than pre-surgery levels. In the low supplement group, mean plasma vitamin levels were in or near marginal or deficient ranges. The majority of subjects consuming supplements of vitamin E, vitamin B-6, and folate near the US RDA maintained normal vitamin status. Subjects taking more than 100 micrograms vitamin B-12 daily had adequate vitamin B-12 status. Significant correlations (r = .67 to .94) were observed between vitamin supplement levels and the respective plasma vitamin concentrations.

Pulsatile intravenous gonadotropin-releasing hormone for ovulation-induction in infertile women. II. Analysis of follicular and luteal phase responses.

Pulsatile intravenous gonadotropin releasing hormone (IV-GnRH) was used in 36 infertile patients with primary amenorrhea (n = 5), secondary amenorrhea due to hypothalamic chronic anovulation (HCA) (n = 22), hyperprolactinemia (n = 1) or polycystic ovary syndrome (PCOS) (n = 5), and oligomenorrhea (n = 3), using several dosage and timing regimens. Early follicular phase responses showed four patterns: type 1 consisted of a delayed follicle-stimulating hormone (FSH) peak and was seen with severe hypothalamic suppression (n = 4); type 2 consisted of a brisk and dominant FSH peak on the first day of treatment, and occurred with mild to moderate hypothalamic suppression (n = 19); type 3, which consisted of an FSH peak accompanied by an immediate and exaggerated luteinizing hormone (LH) rise, occurred with mild PCOS and some cases of HCA (n = 5); and type 4, in which LH levels were high to begin with and neither FSH nor LH levels rose with GnRH, occurred with severe PCOS (n = 2). Exaggerated estradiol responses within 24 hours of therapy were seen in eight cycles: in four cases no ovarian abnormality was apparent; in three cases a dominant follicle was already present; and in one case ovarian hyperstimulation was diagnosed ultrasonographically. With standard human chorionic gonadotropin luteal phase support, luteal phase defects were rare with HCA but common with PCOS.

Testicular function in potential sperm donors: normal ranges and the effects of smoking and varicocele.

Testicular exocrine (semen analysis) and endocrine (plasma LH, FSH, prolactin and testosterone) function was assessed in 119 consecutive healthy men presenting for screening as potential sperm donors. Since these volunteers were unbiased with respect to their fertility status, this sample of the general male population was suitable to determine normal ranges and the influence of a variety of physical (height, weight, standardized body weight, varicocele) and demographic (age, marital and fertility status, tobacco and alcohol consumption) factors on normal human testicular endocrine and exocrine function, without the confounding effects of bias in selection of subjects. The statistical distribution of all seminal parameters was non-gaussian, but cube-root transformation of the data normalized the distribution, allowing for parametric statistical analysis. The median (and 95% confidence limits) for the various semen parameters was 73.0 (10.6-235.3) million sperm per ml; 189.0 (12.6-868) million sperm per ejaculate; 50.4 (5.9-181.9) million motile sperm per ml; 133.0 (6.9-661.7) million motile sperm per ejaculate; 54.0 (7.0-172.9) million morphologically normal sperm per ml and 138.5 (7.5-672) million morphologically normal sperm per ejaculate. Testicular volume was correlated positively with measures of physique such as standardized body weight (r = 0.25, P less than 0.01) and body surface area (r = 0.30, P less than 0.002), and negatively with plasma levels of FSH (r = -0.31), P less than 0.002) but not LH. Sperm output was positively correlated with testicular volume (r = 0.28, P less than 0.005) and negatively correlated with plasma FSH (r = -0.31, P less than 0.002) and plasma LH (r = -0.31, P less than 0.002). Smoking was associated with a highly significant reduction in sperm output and motility. Men with varicocele (25%) were significantly taller, had slightly lower haemoglobin levels and moderate left (but not right) testicular atrophy, but neither seminal nor hormonal parameters were different from men without varicocele. There was no difference in any markers of human testicular function between men according to marital or fertility status, grades of moderate alcohol consumption or the presence of low titres of sperm antibodies.

Young's syndrome. Obstructive azoospermia and chronic sinopulmonary infections.

We studied 29 men with Young's syndrome, a combination of obstructive azoospermia and chronic sinopulmonary infections. Men with this syndrome have only mildly impaired respiratory function and normal spermatogenesis; the azoospermia is due to obstruction of the epididymis by inspissated secretions. The diagnosis is based on the occurrence of chronic sinopulmonary infections, persistent azoospermia, normal spermatogenesis, and characteristic epididymal findings, as well as exclusion of cystic fibrosis and the immotile-cilia syndrome. The sperm themselves appear to be normal in Young's syndrome. Pregnancies had occurred in five couples; in three paternity was documented by genotyping. Thus, improved microsurgical and medical therapy might restore fertility. We suggest that Young's syndrome has a prevalence comparable to that of Klinefelter's syndrome and is a common cause of both chronic sinopulmonary infection and azoospermia.