Ulrich A. Knuth

Bio: Ulrich A. Knuth is an academic researcher from University of Münster. The author has contributed to research in topics: Semen analysis & Azoospermia. The author has an hindex of 14, co-authored 16 publications receiving 780 citations.

Effect of Flutamide or Cyproterone Acetate on Pituitary and Testicular Hormones in Normal Men

Abstract: To test the effects of antiandrogen treatment on the endocrine system 20 normal young men were treated with 750 mg/day flutamide [4-nitro 3′-trifluoromethylisobutyranilide (FLU)] or 100 mg/day cyproterone acetate (CPA) for 14 days followed or preceded by a placebo treatment of the same duration 4 weeks apart. Allocation of both drugs and sequence of active and placebo substance was by random number in a double blind design. On days 1 and 14 two basal blood samples were obtained 15 min apart followed by an iv injection of 25 μg GnRH and 10 mg metoclopramide (MTCL). Subsequently blood samples were taken after 25, 45, 60, and 90 min. On day 8 the GnRH/MTCL test was performed after 13 basal blood samples were obtained to establish a baseline for PRL concentrations unbiased by short term stress. After 14 days of FLU treatment, serum testosterone (T) increased significantly [17.4 ± 1.4 (SE) vs. 26.9 ± 1.5 nmol/ liter, as well as estradiol (E2) concentrations (144 ± 12 vs. Ill ± 20 pmol/liter). Dihydrot...

Treatment of Severe Oligospermia with Human Chorionic Gonadotropin/Human Menopausal Gonadotropin: A Placebo-Controlled, Double Blind Trial

Abstract: In an effort to evaluate the effect of hCG/human menopausal gonadotropin (hMG) treatment on semen parameters in normogonadotropic men suffering from oligospermia, a double blind, placebo-controlled study was conducted After 2 basal examinations of seminal parameters and reproductive hormones, 39 men were recruited for the trial Nineteen men, allocated randomly to the active drug group, received im injections of 2500 IU hCG twice a week in combination with 150 IU hMG three times a week for 13 weeks, while 20 men were treated, following the same injection schedule, with NaCl only After the 13-week treatment period, follow-up examination was performed, followed by 3 additional examinations at 4-week intervals Of those men receiving hCG-hMG, 2 induced pregnancies in their wives, while no pregnancies were reported in the placebo group Sperm concentrations, the percentages of motile sperm, and the proportions of normally formed spermatozoa, however, were similar in the 2 groups at all times It was not pos

Advances in male contraception.

Abstract: Despite significant advances in contraceptive options for women over the last 50 yr, world population continues to grow rapidly. Scientists and activists alike point to the devastating environmental impacts that population pressures have caused, including global warming from the developed world and hunger and disease in less developed areas. Moreover, almost half of all pregnancies are still unwanted or unplanned. Clearly, there is a need for expanded, reversible, contraceptive options. Multicultural surveys demonstrate the willingness of men to participate in contraception and their female partners to trust them to do so. Notwithstanding their paucity of options, male methods including vasectomy and condoms account for almost one third of contraceptive use in the United States and other countries. Recent international clinical research efforts have demonstrated high efficacy rates (90-95%) for hormonally based male contraceptives. Current barriers to expanded use include limited delivery methods and perceived regulatory obstacles, which stymie introduction to the marketplace. However, advances in oral and injectable androgen delivery are cause for optimism that these hurdles may be overcome. Nonhormonal methods, such as compounds that target sperm motility, are attractive in their theoretical promise of specificity for the reproductive tract. Gene and protein array technologies continue to identify potential targets for this approach. Such nonhormonal agents will likely reach clinical trials in the near future. Great strides have been made in understanding male reproductive physiology; the combined efforts of scientists, clinicians, industry and governmental funding agencies could make an effective, reversible, male contraceptive an option for family planning over the next decade.

A critical review of the physiological importance and analysis of sperm movement in mammals

Abstract: The identification of human sperm hyperactivated motility has potential importance in sperm function tests, as well as in quality control assays and in reproductive toxicology investigations. However, relatively little is known about this phenomenon and the variety of definitions used for hyperactivation has led to a great deal of confusion as to its occurrence and physiological relevance. This presentation is a critical review of a number of aspects of hyperactivated motility, including its identification and potential role(s) in mammalian fertilization. The initial sections of the review consider the mechanisms involved in the development and maintenance of mammalian sperm motility, and the structural and functional changes in spermatozoa which occur during transport through the female reproductive tract. The methods available for the quantification of aspects of sperm movement are also discussed, with an historical overview of sperm movement analysis.

Anabolic-androgenic steroid therapy in the treatment of chronic diseases

Abstract: The purpose of this study was to review the preclinical and clinical literature relevant to the efficacy and safety of anabolic androgen steroid therapy for palliative treatment of severe weight loss associated with chronic diseases. Data sources were published literature identified from the Medline database from January 1966 to December 2000, bibliographic references, and textbooks. Reports from preclinical and clinical trials were selected. Study designs and results were extracted from trial reports. Statistical evaluation or meta-analysis of combined results was not attempted. Androgenic anabolic steroids (AAS) are widely prescribed for the treatment of male hypogonadism; however, they may play a significant role in the treatment of other conditions as well, such as cachexia associated with human immunodeficiency virus, cancer, burns, renal and hepatic failure, and anemia associated with leukemia or kidney failure. A review of the anabolic effects of androgens and their efficacy in the treatment of these conditions is provided. In addition, the numerous and sometimes serious side effects that have been known to occur with androgen use are reviewed. Although the threat of various side effects is present, AAS therapy appears to have a favorable anabolic effect on patients with chronic diseases and muscle catabolism. We recommend that AAS can be used for the treatment of patients with acquired immunodeficiency syndrome wasting and in severely catabolic patients with severe burns. Preliminary data in renal failure-associated wasting are also positive. Advantages and disadvantages should be weighed carefully when comparing AAS therapy to other weight-gaining measures. Although a conservative approach to the use of AAS in patients with chronic diseases is still recommended, the utility of AAS therapy in the attenuation of severe weight loss associated with disease states such as cancer, postoperative recovery, and wasting due to pulmonary and hepatic disease should be more thoroughly investigated.

Environmental/lifestyle effects on spermatogenesis

Abstract: The high incidence of low sperm counts in young (European) men and evidence for declining sperm counts in recent decades mean that the environmental/lifestyle impact on spermatogenesis is an important health issue. This review assesses potential causes involving adverse effects on testis development in perinatal life (primarily effects on Sertoli cell number), which are probably irreversible, or effects on the process of spermatogenesis in adulthood, which are probably mainly reversible. Several lifestyle-related (obesity, smoking) and environmental (exposure to traffic exhaust fumes, dioxins, combustion products) factors appear to negatively affect both the perinatal and adult testes, emphasizing the importance of environmental/lifestyle impacts throughout the life course. Apart from this, public concern about adverse effects of environmental chemicals (ECs) (pesticides, food additives, persistent pollutants such as DDT, polychlorinated biphenyls) on spermatogenesis in adult men are, in general, not supported by the available data for humans. Where adverse effects of ECs have been shown, they are usually in an occupational setting rather than applying to the general population. In contrast, a modern Western lifestyle (sedentary work/lifestyle, obesity) is potentially damaging to sperm production. Spermatogenesis in normal men is poorly organized and inefficient so that men are poorly placed to cope with environmental/lifestyle insults.

Endocrine disruptors and estrogenic effects on male reproductive axis

Abstract: Endocrine disruptors (e.g., polychlorinated biphenyls [PCBs], dichlorodiphenyl-trichloroethane [DDT], dioxin, and some pesticides) are estrogen-like and anti-androgenic chemicals in the environment. They mimic natural hormones, inhibit the action of hormones, or alter the normal regulatory function of the endocrine system and have potential hazardous effects on male reproductive axis causing infertility. Although testicular and prostate cancers, abnormal sexual development, undescended testis, chronic inflammation, Sertoli-cell-only pattern, hypospadias, altered pituitary and thyroid gland functions are also observed, the available data are insufficient to deduce worldwide conclusions. The development of intra-cytoplasmic sperm injection (ICSI) is beyond doubt the most important recent breakthrough in the treatment of male infertility, but it does not necessarily treat the cause and may inadvertently pass on adverse genetic consequences. Many well-controlled clinical studies and basic scientific discoveries in the physiology, biochemistry, and molecular and cellular biology of the male reproductive system have helped in the identification of greater numbers of men with male factor problems. Newer tools for the detection of Y-chromosome deletions have further strengthened the hypothesis that the decline in male reproductive health and fertility may be related to the presence of certain toxic chemicals in the environment. Thus the etiology, diagnosis, and treatment of male factor infertility remain a real challenge. Clinicians should always attempt to identify the etiology of a possible testicular toxicity, assess the degree of risk to the patient being evaluated for infertility, and initiate a plan to control and prevent exposure to others once an association between occupation/toxicant and infertility has been established.