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Biomedical subjects

W J Bremner

Publications and source records attributed to W J Bremner.

At least 19 recordsLinked to original sources
PubMed2006

Miglustat has no apparent effect on spermatogenesis in normal men.

BACKGROUND: In mice, administration of the glycosphingolipid biosynthesis inhibitor miglustat results in reversible infertility, characterized by impaired sperm motility and markedly abnormal sperm morphology. This observation suggested that miglustat might have utility for fertility control in man. To ascertain the impact of miglustat on human spermatogenesis, we conducted a pilot study of miglustat administration in normal men. METHODS: After a 2-week baseline period, seven normal men were administered miglustat 100 mg, orally, twice daily for 6 weeks. During treatment, subjects had frequent seminal fluid analyses to assess the impact of treatment on sperm concentration, motility and morphology and the ability to undergo the acrosome reaction by in vitro assays. RESULTS: Five subjects completed all aspects of the study. In these subjects, there was no apparent effect of miglustat on sperm concentration, motility or sperm morphology after 6 weeks of therapy. In addition, no changes in acrosome structure or function were observed with treatment, despite therapeutic concentrations of miglustat in the serum and seminal plasma. All subjects experienced gastrointestinal upset, diarrhoea and mild weight loss during treatment. No other abnormalities in blood counts, serum chemistries, vision or overall health were observed. CONCLUSION: In contrast to the observations in mice, the oral administration of miglustat does not appear to affect human spermatogenesis. Further elucidation of the mechanism underlying the species specificity of miglustat may improve our understanding of the role of glycosphingolipids in spermatogenesis and result in alternative approaches to male fertility control.

1-Deoxynojirimycin↗
PubMed2006

Acceptability of an injectable male contraceptive regimen of norethisterone enanthate and testosterone undecanoate for men.

BACKGROUND: We assessed attitudes towards and acceptability of male hormonal contraception among volunteers participating in a clinical trial of a prototype regimen, consisting of progestin and testosterone injections. METHODS: After completing screening, eligible men were randomly assigned to the no-treatment group (n = 40) or to receive injections of norethisterone enanthate and testosterone undecanoate or placebo at different intervals (n = 50) according to a blocked randomization list. They underwent self-administered questionnaires. RESULTS: The average age of the participants was approximately 28 years; most were involved in a stable relationship and had no children. Ninety-two percentage of the respondents thought that men and women should share responsibility for contraception and 75% said they would try a hormonal contraceptive if available. At the end of the treatment phase, 66% of the participants said that they would use such a method, and most rated its acceptability very highly; none reported it to be unacceptable. The injections themselves were indicated as the biggest disadvantage. No significant changes in sexual function or mood states were detected among the men who underwent hormone injections. CONCLUSIONS: The contraceptive tested in this study was well accepted by the participants over the course of 1 year.

Adult↗
PubMed2005

A multicentre study investigating subcutaneous etonogestrel implants with injectable testosterone decanoate as a potential long-acting male contraceptive.

BACKGROUND: The combination of etonogestrel implants with injectable testosterone decanoate was investigated as a potential male contraceptive. METHODS: One hundred and thirty subjects were randomly assigned to three treatment groups, all receiving two etonogestrel rods (204 mg etonogestrel) and 400 mg testosterone decanoate either every 4 weeks (group I, n = 42), or every 6 weeks (group II, n = 51) or 600 mg testosterone decanoate every 6 weeks (group III, n = 37) for a treatment period of 48 weeks. RESULTS: One hundred and ten men completed 48 weeks of treatment. Sperm concentrations of <1 x 10(6)/ml were achieved in 90% (group I), 82% (group II) and 89% (group III) of subjects by week 24. Suppression was slower in group II, which also demonstrated more frequent escape from gonadotrophin suppression than groups I and III. Peak testosterone concentrations remained in the normal range throughout in all groups. Mean trough testosterone concentrations were initially subphysiological but increased into the normal range during treatment. Mean haemoglobin levels increased in group I, and a non-significant increase in weight and decline in high-density lipoprotein cholesterol was observed in all groups. Fourteen subjects discontinued treatment due to adverse events. CONCLUSIONS: Subcutaneous etonogestrel implants in combination with injectable testosterone decanoate resulted in profound suppression of spermatogenesis that could be maintained for up to 1 year. Efficacy of suppression was less in group II, probably due to inadequate testosterone dosage. This combination has potential as a long-acting male hormonal contraceptive.

Administration, Cutaneous↗
PubMed2005

Norethisterone enanthate plus testosterone undecanoate for male contraception: effects of various injection intervals on spermatogenesis, reproductive hormones, testis, and prostate.

The goal of this study was to find the most favorable injection interval of norethisterone enanthate (NETE) plus testosterone undecanoate (TU) in terms of gonadotropin, sperm suppression, and prostatic effects. Fifty normal men were randomly assigned to receive NETE 200 mg plus TU 1000 mg every 8 wk (n = 10), every 12 wk (n = 10), every 6 wk for 12 wk and then every 12 wk (n = 10), and every 6 wk for 12 wk and thereafter TU 1000 mg plus placebo every 12 wk (n = 10), and placebo plus placebo every 6 wk for 12 wk and then every 12 wk (n = 10) for 48 wk. Semen analyses, blood drawings, physical examinations, and prostate ultrasounds were performed throughout the study. Of the men in the 8-wk injection group, 90% (nine of 10) achieved azoospermia, compared with 37.5% (three of eight) in the 12-wk injection group (P = 0.019). TU plus placebo injected every 12 wk did not maintain sperm suppression. Prostate volumes did not change significantly in either group. In conclusion, these data suggest that the combined administration of NETE and TU at 8-wk intervals represents an effective hormonal contraceptive regimen.

Adolescent↗
PubMed2003

Testosterone undecanoate maintains spermatogenic suppression induced by cyproterone acetate plus testosterone undecanoate in normal men.

In this study we evaluated whether testosterone undecanoate (TU), alone or combined with low dose cyproterone acetate (CPA), can maintain spermatogenic suppression induced by higher doses of CPA plus TU. Twenty-four men received for 12 wk 20 mg/d CPA plus 1000 mg/6 wk TU and then 1000 mg/8 wk TU plus 20 mg/d CPA (n = 8), 2 mg/d CPA (n = 8), or plus placebo (n = 8) for 32 wk. Blood samples, physical examinations, hormones, chemistry, hematology, semen analysis, and sexual/behavioral assessments were performed throughout the study. Sperm counts decreased to less than 1 million/ml in all subjects by wk 12, and 54% of them achieved azoospermia. Suppression of sperm counts was maintained until wk 44. Serum LH and FSH levels were suppressed by wk 12 of hormone administration and remained suppressed until wk 44. No significant changes in any biochemical parameters were detected at wk 44 in any group. There was a slight increase in total prostate volume to within the normal range at wk 44 that returned to baseline 1 yr after stopping hormone administration. In conclusion, TU alone or combined with lower doses of CPA maintains sperm suppression induced by higher dose CPA plus TU for 32 wk. This prototype regimen represents a promising male contraceptive regimen.

Adult↗
PubMed2002

Cognitive effects of short-term manipulation of serum sex steroids in healthy young men.

We examined the effects of sex steroids on cognitive functioning by exogenously manipulating circulating T levels in a group of healthy young men. Thirty-two men were randomized to receive 8 wk of treatment including: 1) im T enanthate 100 mg/wk plus daily oral placebo (T); 2) im placebo/wk plus 125 microg daily oral levonorgestrel (LNG); 3) im T enanthate 100 mg/wk plus 125 microg daily oral LNG (T + LNG); 4) im placebo/wk plus daily oral placebo. Cognitive functions were assessed at baseline and twice during treatment. Serum T and E2 levels were significantly increased in the T and T + LNG groups compared with baseline (P < 0.01) and T levels were significantly decreased in the LNG group (P < 0.05). Verbal memory significantly decreased in the LNG group (P < 0.01) and was maintained by coadministration of T in the T + LNG group. Divided attention was unaffected in the LNG group but improved significantly in the T + LNG group. In summary, decreased serum T levels induced by LNG or direct effects of the progestin, LNG, adversely affects verbal memory in normal young men. These results suggest that short-term changes in sex steroid levels have effects on cognitive function in healthy young men.

Administration, Oral↗
PubMed2001

Impairment of spermatogonial development and spermiation after testosterone-induced gonadotropin suppression in adult monkeys (Macaca fascicularis).

Human male hormonal contraceptive regimens do not consistently induce azoospermia, and the basis of this variable response is unclear. This study used nine adult macaque monkeys (Macaca fascicularis) given testosterone (T) implants for 20 weeks to study changes in germ cell populations in relation to sperm output. Germ cell numbers were determined using the optical disector stereological method. Four animals achieved consistent azoospermia (azoo group), whereas five animals did not (nonazoo group). T-induced gonadotropin suppression in all animals decreased A pale (Ap) spermatogonia to 45% of baseline within 2 weeks, leading to decreased B spermatogonia (32--38%) and later germ cells (20--30%) after 14 and 20 weeks. Though the reduction in later germ cell types could be primarily attributed to the loss of spermatogonia, the data suggested that some cells were lost during the spermatocyte and spermatid phase of development. B spermatogonial number was more markedly suppressed in azoospermic animals, compared with the nonazoo group, as was the conversion ratio between Ap and B spermatogonia. Abnormal retention of elongated spermatids (failed spermiation) was also prominent in some animals after long-term T administration. We conclude that: 1) the variable suppression of sperm output is attributed to the degree of inhibition of germ cell development from type B spermatogonia onwards, and this is related to the degree of FSH suppression; and 2) inhibition of Ap and B spermatogonial development and of spermiation are the major defects caused by long-term T administration to monkeys.

Animals↗
PubMed2000

Desogestrel plus testosterone effectively suppresses spermatogenesis but also causes modest weight gain and high-density lipoprotein suppression.

OBJECTIVE: To test the hypothesis that oral desogestrel (DSG) plus testosterone would uniformly and rapidly suppress sperm concentrations in young men as effectively as levonorgestrel (LNG) plus testosterone and cause less high-density lipoprotein (HDL) suppression and weight gain. DESIGN: Single-blind, randomized trial. SETTING: VA Puget Sound and University of Washington, Seattle, Washington. PATIENT(S): Twenty-four healthy young men, aged 20-49. INTERVENTION(S): Subjects were randomized to three groups of men who were administered 6 months of therapy with oral DSG plus im testosterone enanthate: 150 microg of DSG plus 50 mg of testosterone (DSG 150-T 50), 150 microg of DSG plus 100 mg of testosterone (DSG 150-T 100) or 300 microg of DSG plus 100 mg of testosterone (DSG 300-T 100). We compared these three groups to two groups of historical controls of 100 mg of im testosterone alone or 150 microg of oral LNG plus 100 mg of im testosterone (LNG 125-T 100 group) enrolled in similar studies. MAIN OUTCOME MEASURE(S): Suppression of sperm counts to severe oligoazoospermia (sperm counts <1 x 10(6)/mL) and azoospermia, weight gain, and serum high-density cholesterol (HDL) suppression. RESULT(S): Azoospermia was achieved in all eight men receiving DSG 150-T 100 and seven of the eight men in the DSG 300-T 100 group. DSG 150 or 300 plus T 100 suppressed spermatogenesis as effectively as LNG 125-T 100 and more effectively than DSG 50-T 100 or testosterone alone. All groups tended to gain weight compared with their baseline, but the weight gain was greatest (and statistically significant) in the DSG 150-T 100, DSG 300-T 100, and LNG 125-T 100 groups. Serum HDL levels were modestly suppressed in all groups, and this effect was greatest in the DSG 300-T 100 and LNG 125-T 100 groups. CONCLUSION(S): The combination of DSG plus testosterone is a very effective regimen for suppression of spermatogenesis and has acceptably low side effects.

Acne Vulgaris↗
PubMed2000

Newer agents for hormonal contraception in the male.

Efforts to create a hormonal contraceptive for men use testosterone to suppress the production of pituitary gonadotropins and, hence, spermatogenesis. However, conventional testosterone must be administered by frequent injection, and when given alone, is not 100% effective. Therefore, newer androgens and agents that synergistically suppress gonadotropin production are being studied to create an effective and commercially viable contraceptive.

Androgens↗
PubMed2000

Ovarian follicular concentrations of activin, follistatin, inhibin, insulin-like growth factor I (IGF-I), IGF-II, IGF-binding protein-2 (IGFBP-2), IGFBP-3, and vascular endothelial growth factor in spontaneous menstrual cycles of normal women of advanced reproductive age.

Previous studies indicate that the menstrual cycles of older reproductive age women are characterized by a selective elevation of FSH associated with early development and ovulation of a dominant follicle. Several intraovarian hormones and growth factors have been identified that appear to serve important paracrine roles. The purpose of this study was to examine follicular fluid (FF) hormones and growth factors in the dominant follicle of unstimulated cycles of older, ovulatory women. We aspirated FF from the preovulatory dominant follicle in natural menstrual cycles of older subjects (age, 40-45 yr; n = 20) and younger controls (age, 20-25 yr; n = 19). FF was analyzed for estradiol, progesterone, testosterone, androstenedione, inhibin A and B, total activin A, total follistatin, insulin-like growth factor I (IGF-I), IGF-II, IGF-binding protein-2 (IGFBP-2), IGFBP-3, and vascular endothelial growth factor (VEGF) concentrations. We found that the dominant follicles from older women contain normal concentrations of steroids, inhibin A and B, IGF-II, IGFBP-2, and IGFBP-3; increased concentrations of follistatin, activin A, and VEGF; and decreased concentrations of IGF-I. Therefore, under the influence of elevated FSH, the dominant follicle in older women is highly competent in terms of hormone and growth factor secretion. We postulate that elevated FF activin may be related to the early ovulation observed in older women, whereas elevated VEGF may be related to the meiotic spindle abnormalities observed in the oocytes of older reproductive age women.

Activins↗
PubMed2000

Quantitative and qualitative changes in serum luteinizing hormone after injectable testosterone undecanoate treatment in hypogonadal men.

AIM: To clarify the immuno-active LH (i-LH) and bioactive LH (b-LH) responses and qualitative changes in the circulating LH to testosterone undecanoate (TU) injection. METHODS: Eight men with Klinefelter's syndrome were recruited for the study. They received crossover injections of TU at doses of 500 and 1000 mg. Serum i-LH and b-LH levels before and at various time intervals after TU injection were measured and the serum i-LH, b-LH, b-LH/i-LH (B/I) and testosterone/sex hormone-binding globulin (T/SHBG) ratio in LH-responders and LH non-responders were compared. RESULTS: A parallel suppression of serum i-LH and b-LH was consistent with their overall high correlation between each other (r = 0.84, P < 0.001). Mean serum i-FSH levels were decreased by TU injection at both doses without dose-response effects. LH-responders had lower baseline serum i-LH and b-LH, and higher E2 levels and T/SHBG ratio. There was a quantitative change in serum LH as induced by TU without qualitative change within LH-responders os LH-non-responders. CONCLUSION: A high loading dose (1000 mg) of TU is important for the initial suppression of LH. With the lower dose (500 mg), repeated injections will be required to attain such LH suppression for the purpose of fertility regulation. The lower baseline serum i-LH level may be an intrinsic characteristic of LH-responders.

Adolescent↗
PubMed1999

A clinical trial of injectable testosterone undecanoate as a potential male contraceptive in normal Chinese men.

This is a pilot dose-finding study of spermatogenic suppression using testosterone undecanoate (TU) injections alone in normal Chinese men. Thirty-two healthy men were recruited. Volunteers underwent pretreatment evaluation, then a treatment period in which group I (n = 13) received 500 mg TU, group II (n = 12) received 1000 mg TU, and group III (n = 7) received placebo, respectively, at monthly intervals during the treatment period (or until azoospermia was achieved). Thereafter, they underwent a recovery period until all parameters returned to pretreatment levels. Eleven of 12 volunteers in the 500-mg TU group, and all volunteers in the 1000-mg TU group became azoospermic. Faster suppression of spermatogenesis was achieved in the 1000-mg TU group. Serum testosterone increased significantly in the higher dose group at weeks 8 and 12, but remained within the normal range. Mean serum LH and FSH were profoundly suppressed by both doses to undetectable levels at week 16. TU injections did not cause a significant change in high density lipoprotein cholesterol levels. No serious side-effects were found. We conclude that both dosages of TU can effectively, safely, and reversibly suppress spermatogenesis in normal Chinese men.

Adult↗
PubMed1998

Klinefelter syndrome.

Klinefelter syndrome is the most common sex chromosome disorder. Affected males carry an additional X chromosome, which results in male hypogonadism, androgen deficiency, and impaired spermatogenesis. Some patients may exhibit all of the classic signs of this disorder, including gynecomastia, small testes, sparse body hair, tallness, and infertility, whereas others, because of the wide variability in clinical expression, lack many of these features. Treatment consists of testosterone replacement therapy to correct the androgen deficiency and to provide patients with appropriate virilization. This therapy also has positive effects on mood and self-esteem and has been shown to protect against osteoporosis, although it will not reverse infertility. Although the diagnosis of Klinefelter syndrome is now made definitively using chromosomal karyotyping, revealing in most instances a 47,XXY genotype, the diagnosis also can be made using a careful history and results of a physical examination, with the hallmark being small, firm testes. As it affects 1 in 500 male patients and presents with a variety of clinical features, primary care physicians should be familiar with this condition.

Diagnosis, Differential↗
PubMed1998

Immature spermatids are not prevalent in semen from men who are receiving androgen-based contraceptive regimens.

OBJECTIVE: To determine whether immature spermatids increase in semen in response to hormonal contraceptive treatments. Such a finding would support the existence of a defect in spermiogenesis, which in turn may explain the reported variability in sperm output. DESIGN: Semen smears were obtained from healthy men undergoing randomized control trials of T plus progestin contraceptive treatments. PATIENT(S): Healthy men (21-49 years) with normal semen analyses received T (50-100 mg IM weekly) in combination with either desogestrel (150-300 microg daily, n = 5) or levonorgestrel (125-250 microg daily, n = 10) for 24 weeks. Semen smears were made during spermatogenic suppression and recovery. Nine control subjects were also assessed. MAIN OUTCOME MEASURE(S): Semen analyses were performed using World Health Organization criteria. Immature spermatids and white blood cells in semen were identified by immunostaining with monoclonal antibodies to the human intra-acrosomal antigen SP-10 and the ubiquitous white cell CD-45 antigen, respectively. RESULT(S): In a total of 14 normal ejaculates (9 control and 5 pretreatment) 74+/-14 million/mL sperm (mean+/-SEM) were seen together with a few immature spermatids (0.69+/-0.20 million/mL). During contraceptive treatments, spermatid number decreased in parallel with the sperm concentration and spermatids disappeared in most subjects. No significant changes were seen in either leukocyte or immunonegative round cell concentration (0.41+/-0.25 and 0.25+/-0.09 million/mL in controls, respectively) in response to treatments. CONCLUSION(S): Spermatid sloughing, as assessed by the ejaculation of immature spermatids, is not a feature of T-induced spermatogenic regression in men; rather, the decline in both mature and immature germ cells in the ejaculate probably results from a decline in the number of precursor cells, ultimately resulting in severe oligo- or azoospermia. Detailed studies on the sites of spermatogenic interruption are required to understand the variability in responses seen after contraceptive therapies in men.

Adult↗
PubMed1998

The use of testosterone as a male contraceptive.

Testosterone functions as a contraceptive by suppressing secretion of the pituitary gonadotropins luteinizing hormone and follicle stimulating hormone. Low levels of these hormones decrease endogenous testosterone secretion from the testis and deprive developing sperm of the signals required for normal maturation. Interference with sperm maturation causes a decline in sperm production and can lead to reversible infertility in men, raising the possibility that testosterone could be utilized in a commercially available contraceptive. To this end, testosterone has been studied alone and in combination with either gonadotropin releasing hormone analogues or progestins in efforts to improve its contraceptive efficacy. In this chapter, we will review efforts to use testosterone to create a safe, convenient, efficacious contraceptive method for men.

Contraception↗
PubMed1998

Low dose of cyproterone acetate and testosterone enanthate for contraception in men.

After a control phase, 10 normal men received cyproterone acetate (CPA) at a dose of 25 mg/day (CPA-25; n=5) or 12.5 mg/day (CPA-12.5; n=5) plus testosterone enanthate (TE) 100 mg/week, for 16 weeks. Throughout the study sperm counts were performed every 2 weeks, and luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, biochemical and haematological tests were performed every 4 weeks. All five men in group CPA-25 and three men in group CPA-12.5 achieved azoospermia. One man in group CPA-25 was azoospermic by week 12 of hormone administration, but had a sperm count of 0.1 x 10(6)/ml at week 16. Time to azoospermia was 9.0+/-1.3 and 8.7+/-0.7 weeks in groups CPA-25 and CPA-12.5 respectively. Gonadotrophins were decreased by week 4 of hormone administration, remained around the minimum detectability of the assay for the duration of hormone administration and returned to baseline after stopping hormone administration. Testosterone values did not change. No change in any biochemical parameters was found. Haematological parameters were decreased at week 16 of hormone administration and returned to baseline after stopping hormone administration. In conclusion, these results suggest that an hormonal regimen consisting of testosterone plus a progestin with anti-androgenic properties holds promise as an effective, safe and reversible male contraceptive.

Adult↗