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Dive into the research topics where Michael Zitzmann is active.

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Featured researches published by Michael Zitzmann.


The Lancet | 2004

Klinefelter's syndrome

Fabio Lanfranco; Axel Kamischke; Michael Zitzmann; Eberhard Nieschlag

Klinefelters syndrome is the most common genetic cause of human male infertility, but many cases remain undiagnosed because of substantial variation in clinical presentation and insufficient professional awareness of the syndrome itself. Early recognition and hormonal treatment of the disorder can substantially improve quality of life and prevent serious consequences. Testosterone replacement corrects symptoms of androgen deficiency but has no positive effect on infertility. However, nowadays patients with Klinefelters syndrome, including the non-mosaic type, need no longer be considered irrevocably infertile, because intracytoplasmic sperm injection offers an opportunity for procreation even when there are no spermatozoa in the ejaculate. In a substantial number of azoospermic patients, spermatozoa can be extracted from testicular biopsy samples, and pregnancies and livebirths have been achieved. The frequency of sex chromosomal hyperploidy and autosomal aneuploidies is higher in spermatozoa from patients with Klinefelters syndrome than in those from normal men. Thus, chromosomal errors might in some cases be transmitted to the offspring of men with this syndrome. The genetic implications of the fertilisation procedures, including pretransfer or prenatal genetic assessment, must be explained to patients and their partners.


Diabetes Care | 2011

Low Testosterone Associated With Obesity and the Metabolic Syndrome Contributes to Sexual Dysfunction and Cardiovascular Disease Risk in Men With Type 2 Diabetes

Christina Wang; Graham Jackson; T. Hugh Jones; Alvin M. Matsumoto; Ajay Nehra; Michael A. Perelman; Ronald S. Swerdloff; Abdul Traish; Michael Zitzmann; Glenn R. Cunningham

Men with obesity, the metabolic syndrome, and type 2 diabetes have low total and free testosterone and low sex hormone–binding globulin (SHBG). Conversely, the presence of low testosterone and/or SHBG predicts the development of metabolic syndrome and type 2 diabetes. Visceral adiposity present in men with low testosterone, the metabolic syndrome, and/or type 2 diabetes acts through proinflammatory factors. These inflammatory markers contribute to vascular endothelial dysfunction with adverse sequelae such as increased cardiovascular disease (CVD) risk and erectile dysfunction. This review focuses on the multidirectional impact of low testosterone associated with obesity and the metabolic syndrome and its effects on erectile dysfunction and CVD risk in men with type 2 diabetes. Whenever possible in this review, we will cite recent reports (after 2005) and meta-analyses. ### Epidemiological studies of low testosterone, obesity, metabolic status, and erectile dysfunction Epidemiological studies support a bidirectional relationship between serum testosterone and obesity as well as between testosterone and the metabolic syndrome. Low serum total testosterone predicts the development of central obesity and accumulation of intra-abdominal fat (1–3). Also, low total and free testosterone and SHBG levels are associated with an increased risk of developing the metabolic syndrome, independent of age and obesity (1–3). Lowering serum T levels in older men with prostate cancer treated with androgen deprivation therapy increases body fat mass (4). Conversely, high BMI, central adiposity, and the metabolic syndrome are associated with and predict low serum total and to a lesser extent free testosterone and SHBG levels (1–3,5). Because obesity suppresses SHBG and as a result total testosterone concentrations, alterations in SHBG confound the relationship between testosterone and obesity. Low total testosterone or SHBG levels are associated with type 2 diabetes, independent of age, race, obesity, and criteria for diagnosis of diabetes (6,7). In longitudinal studies, low serum total and free testosterone …


The Journal of Sexual Medicine | 2010

Endocrine aspects of male sexual dysfunctions

Jacques Buvat; Mario Maggi; Louis Gooren; André T. Guay; Joel J. Kaufman; Abraham Morgentaler; Claude Schulman; Hui Meng H.M. Tan; Luiz Otavio Torres; Aksam Yassin; Michael Zitzmann

INTRODUCTION Endocrine disorders may adversely affect mens sexual function. AIM To provide recommendations based on best evidence for diagnosis and treatment of endocrine-related male sexual dysfunctions. METHODS The Endocrine Aspects of Male Sexual Dysfunctions Committee, including 11 members from eight countries and four continents, collaborated with the Endocrine subcommittee of the Standards Committee of the International Society for Sexual Medicine. Medical literature was reviewed in detail, followed by extensive internal committee discussion over 2 years, then public presentation and discussion with the other experts before finalizing the report. MAIN OUTCOME MEASURE Recommendations based on grading of evidence-base medical literature and interactive discussion. RESULTS From animal studies, it is derived that testosterone modulates mechanisms involved in erectile machinery, including expression of enzymes that both initiate and terminate erection. In addition, testosterone is essential for sexual motivation. Whether these findings could be extrapolated to human erections is unclear. Testosterone plays a broad role in mens overall health. Recent studies have established strong associations between low testosterone and metabolic and cardiovascular imbalances. In some studies, low testosterone decreased longevity; however, longitudinal studies do not support the predictive value of low testosterone for further cardiovascular events. The article proposes a standardized process for diagnosis and treatment of endocrine-related male sexual dysfunctions, updating the knowledge on testosterone and prostate safety. There is no compelling evidence that testosterone treatment causes prostate cancer or its progression in men without severe testosterone deficiency (TD). The possible roles of prolactin and thyroid hormones are also examined. CONCLUSIONS Men with erectile dysfunction, hypoactive sexual desire and retarded ejaculation, as well as those with visceral obesity and metabolic diseases, should be screened for TD and treated. Prospective interventional studies are required before screening for TD in more conditions, including cardiovascular diseases, and considering correction as preventive medicine as much data suggests.


The Journal of Sexual Medicine | 2011

Adverse side effects of 5α-reductase inhibitors therapy: persistent diminished libido and erectile dysfunction and depression in a subset of patients.

Abdulmaged M. Traish; John Hassani; André T. Guay; Michael Zitzmann; Michael L. Hansen

INTRODUCTION 5α-reductase inhibitors (5α-RIs), finasteride and dutasteride, have been approved for treatment of lower urinary tract symptoms, due to benign prostatic hyperplasia, with marked clinical efficacy. Finasteride is also approved for treatment of hair loss (androgenetic alopecia). Although the adverse side effects of these agents are thought to be minimal, the magnitude of adverse effects on sexual function, gynecomastia, depression, and quality of life remains ill-defined. AIM The goal of this review is to discuss 5α-RIs therapy, the potential persistent side effects, and the possible mechanisms responsible for these undesirable effects. METHODS We examined data reported in various clinical studies from the available literature concerning the side effects of finasteride and dutasteride. MAIN OUTCOME MEASURES Data reported in the literature were reviewed and discussed. Results.  Prolonged adverse effects on sexual function such as erectile dysfunction and diminished libido are reported by a subset of men, raising the possibility of a causal relationship. CONCLUSIONS We suggest discussion with patients on the potential sexual side effects of 5α-RIs before commencing therapy. Alternative therapies may be considered in the discussion, especially when treating androgenetic alopecia.


Clinical Endocrinology | 2004

Serum adiponectin levels in hypogonadal males: influence of testosterone replacement therapy

Fabio Lanfranco; Michael Zitzmann; Manuela Simoni; Eberhard Nieschlag

objective  Adiponectin is an adipocyte‐specific secretory protein which exhibits antiatherogenic, anti‐inflammatory and antidiabetic properties. We hypothesized that testosterone plays an important role in the regulation of its secretion in humans, as adiponectin concentrations are higher in women than in men and as testosterone administration is accompanied by a reduction in serum adiponectin in animals and by reduced protein secretion in cultured adipocytes. This study aimed to evaluate adiponectin levels in hypogonadal men prior to and during testosterone replacement therapy.


Fertility and Sterility | 2003

Male smokers have a decreased success rate for in vitro fertilization and intracytoplasmic sperm injection

Michael Zitzmann; Claus Rolf; Verena Nordhoff; Guido Schräder; Melanie Rickert-Föhring; Paul Gassner; Hermann M. Behre; Robert R. Greb; Ludwig Kiesel; Eberhard Nieschlag

OBJECTIVE Smoking by one or both partners can adversely affect IVF outcome. We investigated whether smoking may also play a role in the success rate of intracytoplasmic sperm injection (ICSI), in which initial steps of fertilization are bypassed. DESIGN Three hundred one couples (ICSI: 153, IVF: 148) participated in 415 treatment cycles (ICSI: 202, IVF: 213). One hundred thirty-nine men were habitual smokers (ICSI: 71, IVF: 68). Seventy-seven women were smokers (ICSI: 41, IVF: 36). Multiple nominal regression analyses of various steps of assisted reproduction included smoking status, age, semen parameters, and number of embryos transferred. SETTINGS Reproductive and andrology unit of the university. PATIENT(S) Three hundred one couples seeking fertility treatment. INTERVENTION(S) Assisted reproduction by in vitro fertilization (IVF) or ICSI. MAIN OUTCOME MEASURE(S) Clinical pregnancy. RESULT(S) Intracytoplasmic sperm injection success (clinical pregnancy) in women with smoking male partners was 22% and was 38% with nonsmoking partners. Similar results were seen for IVF, with 18% vs. 32%. Multinominal logistic regression analysis revealed smoking in men to be a significant predictor of ICSI outcome, along with female age and the number of embryos transferred, whereas clinical pregnancies after IVF were dependent on smoking in men, number of embryos transferred, sperm motility, and female age. Female smoking influenced the number of oocytes retrieved and the fertilization rate of oocytes in IVF but not in ICSI. The odds ratio for failure of ICSI for male smokers in comparison to male nonsmokers was 2.95 (IVF: 2.65). CONCLUSION(S) Smoking by males decreases the success rates of assisted reproduction procedures, not only in IVF, but also in ICSI. Apart from putative adverse effects during fertilization, altered DNA in spermatozoa might hamper development of the embryo.


The Aging Male | 2015

Recommendations on the diagnosis, treatment and monitoring of hypogonadism in men

Bruno Lunenfeld; George Mskhalaya; Michael Zitzmann; Stefan Arver; Svetlana Kalinchenko; Abraham Morgentaler

Abstract Hypogonadism or Testosterone Deficiency (TD) in adult men as defined by low levels of serum testosterone accompanied by characteristic symptoms and/or signs as detailed further on can be found in long-recognized clinical entities such as Klinefelter syndrome, Kallmann syndrome, pituitary or testicular disorders, as well as in men with idiopathic, metabolic or iatrogenic conditions that result in testosterone deficiency. These recommendations do not encompass the full range of pathologies leading to hypogonadism (testosterone deficiency), but instead focus on the clinical spectrum of hypogonadism related to metabolic and idiopathic disorders that contribute to the majority of cases that occur in adult men.


European Journal of Endocrinology | 2011

Onset of effects of testosterone treatment and time span until maximum effects are achieved

Farid Saad; Antonio Aversa; Andrea M. Isidori; Livia Zafalon; Michael Zitzmann; Louis Gooren

Objective Testosterone has a spectrum of effects on the male organism. This review attempts to determine, from published studies, the time-course of the effects induced by testosterone replacement therapy from their first manifestation until maximum effects are attained. Design Literature data on testosterone replacement. Results Effects on sexual interest appear after 3 weeks plateauing at 6 weeks, with no further increments expected beyond. Changes in erections/ejaculations may require up to 6 months. Effects on quality of life manifest within 3–4 weeks, but maximum benefits take longer. Effects on depressive mood become detectable after 3–6 weeks with a maximum after 18–30 weeks. Effects on erythropoiesis are evident at 3 months, peaking at 9–12 months. Prostate-specific antigen and volume rise, marginally, plateauing at 12 months; further increase should be related to aging rather than therapy. Effects on lipids appear after 4 weeks, maximal after 6–12 months. Insulin sensitivity may improve within few days, but effects on glycemic control become evident only after 3–12 months. Changes in fat mass, lean body mass, and muscle strength occur within 12–16 weeks, stabilize at 6–12 months, but can marginally continue over years. Effects on inflammation occur within 3–12 weeks. Effects on bone are detectable already after 6 months while continuing at least for 3 years. Conclusion The time-course of the spectrum of effects of testosterone shows considerable variation, probably related to pharmacodynamics of the testosterone preparation. Genomic and non-genomic effects, androgen receptor polymorphism and intracellular steroid metabolism further contribute to such diversity.


Clinical Endocrinology | 2001

The CAG repeat polymorphism in the androgen receptor gene affects bone density and bone metabolism in healthy males

Michael Zitzmann; Maik Brune; Britta Kornmann; Jörg Gromoll; Ralf Junker; Eberhard Nieschlag

OBJECTIVE Bone metabolism and bone density (BD) are influenced by sex hormones. Testosterone (T) action is exerted through the androgen receptor (AR). We investigated the potential impact of the CAG repeat (CAGR) polymorphism within the AR gene on BD and bone metabolism in healthy younger males.


The Journal of Clinical Endocrinology and Metabolism | 2008

Male Hormonal Contraception: A Double-Blind, Placebo-Controlled Study

E. Mommers; Wendy M. Kersemaekers; Joerg Elliesen; M. Kepers; Dan Apter; Hermann M. Behre; J. Beynon; Pierre Bouloux; Antonietta Costantino; H.P. Gerbershagen; L. Gronlund; D. Heger-Mahn; Ilpo Huhtaniemi; E.L. Koldewijn; C. Lange; S. Lindenberg; Maria Cristina Meriggiola; E.J.H. Meuleman; Peter Mulders; Eberhard Nieschlag; Antti Perheentupa; Andrew Solomon; L. Vaisala; Frederick C. W. Wu; Michael Zitzmann

BACKGROUND This study was performed to assess spermatogenesis suppression and safety of a new combination of an etonogestrel (ENG) implant combined with testosterone undecanoate (TU) injections for male contraception. This is the first large placebo-controlled study for male hormonal contraception. DESIGN AND STUDY SUBJECTS In this double-blind, multicenter study, we randomly assigned 354 healthy men to receive either a low- or high-release ENG implant sc combined with im TU injections (750 mg every 10 or 12 wk or 1000 mg every 12 wk) or placebo implant and injections. Treatment duration was 42 or 44 wk and posttreatment follow-up at least 24 wk. RESULTS Overall, spermatogenesis was suppressed to 1 million/ml or less at wk 16 in 89% of men, with approximately 94% in two high-release ENG groups. Suppression was maintained up to the end of the treatment period in 91% of men. For all men who completed the treatment period, 3% never achieved 1 million/ml or less. Median recovery time to a sperm concentration above 20 million/ml was 15 wk (mean 17 wk, 95% confidence interval 16-18 wk). Treatment was well tolerated. As compared with the placebo group, more men in the active treatment groups reported adverse events such as weight gain, mood changes, acne, sweating, or libido change. For both spermatogenesis suppression and safety, differences were small between the active treatment groups. CONCLUSIONS The combination of an ENG implant with TU injections is a well-tolerated male hormonal method, providing effective and reversible suppression of spermatogenesis. Although the results are good, there is still room for improvement, possibly by adjusting the dose regimen or changing the mode of application.

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Mario Maggi

University of Florence

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Farid Saad

Bayer HealthCare Pharmaceuticals

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J. Gromoll

University of Münster

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