Papers by Gerhard Weinbauer
Journal of Endocrinology
This study evaluated the effect of bilateral testicular irradiation (2 Gy) on reproductive hormon... more This study evaluated the effect of bilateral testicular irradiation (2 Gy) on reproductive hormones, testicular volume (TV) and sperm parameters in six adult cynomolgus monkeys. Hormone levels (FSH, inhibin B and testosterone (T)) were determined to find the most valuable endocrine marker of irradiation-induced damage. All parameters were analysed at weekly intervals for 14 weeks. Histological evaluation of both testes was performed at week 14 after irradiation when one monkey was castrated and at week 27 when the remaining five monkeys were bilaterally biopsied. A decrease in body weight, TV (30% of the pre-treatment size) and sperm count was observed after irradiation. Severe oligozoospermia was achieved throughout the study but azoospermia was recorded only occasionally. Histological evaluation revealed a heterogeneous picture with patchy arrangement of seminiferous tubules containing advanced germ cell types. An increase (P<0·05) in FSH levels and, to a lesser degree also in T levels, occurred several weeks after irradiation. Inhibin B levels showed a sharp decline (P<0·001) as soon as 1 week after irradiation. FSH and inhibin B did not return to baseline levels during the observation period. A negative correlation was found between FSH and inhibin B values (r= 0·35, P<0·001). Inhibin B correlated positively with testis volume (r=0·73, P<0·001) and sperm counts (r=0·55, P<0·01). In conclusion, this study shows that inhibin B represents an early and more sensitive marker of testicular damage than FSH. Furthermore, the rapid fall of inhibin B after irradiation suggests that this hormone is a direct parameter of premeiotic germ cell proliferation.
Menstrual cyclicity pattern of pair-housed and group-housed cynomolgus monkeys (Macaca fascicularis)
Birth Defects Research Part B Developmental and Reproductive Toxicology
For the duration of the infusion, the fasted animals were placed in a specialised bedding box res... more For the duration of the infusion, the fasted animals were placed in a specialised bedding box restrained with a small sized sock [Picture 4a]. Holes for the mouth and nose area allowed free breathing. Eyes, however, remained covered to minimise the stress level for the animals [Schnell and Gerber, 1997]. Following connection of the port system with the pumping equipment [CADD Micropump, Ambulatory Infusion Pump, Model 5900, Pharmacia Deltec Inc., St. Paul, MN 55112 U.S.A., U.S. Patent number 4,731,058 [Picture 4b], confirmation of free flow [flushing of the system with heparine solution, [5 IU/mL], administration was conducted [5 mg/mL/hour] for twice one hour with a 6 hour interval in between, during which animals were returned to their cages. The dosing regime was performed for 16 animals over 7 days. Animals received a tasty reward (piece of fruit, mealworm) immediately after each dosing for conditioning purposes. Two further animals underwent an additional treatment-free period ...
The common marmoset has been used in a wide range of toxicological research as a model for human ... more The common marmoset has been used in a wide range of toxicological research as a model for human disease, physiology and metabolism. With increasing usage of this species the need for well tolerated non-water based vehicles is becoming increasingly apparent, as absorption and bioavailability of active pharmaceutical ingredients are affected by the solubility of new chemical entities in a given drug formulation. 2 The latter implies the need and search for vehicles permitting acceptable solubility of such compounds. The scientific literature provides little information 3 on dosing non-water based vehicles to nonhuman primates in general and to marmosets specifically. In this context we evaluated oil-based carriers to support drug development programs in the first instance in the marmoset and in the cynomolgus monkey.
The Leydig Cell as a Target for Male Contraception
Contemporary Endocrinology, 2007
Page 1. From: Contemporary Endocrinology: The Leydig Cell in Health and Disease Edited by: AH Pay... more Page 1. From: Contemporary Endocrinology: The Leydig Cell in Health and Disease Edited by: AH Payne and MP Hardy © Humana Press Inc., Totowa, NJ 415 The Leydig Cell as a Target for Male Contraception Craig Marc Luetjens, PhD, Joachim Wistuba, PhD, ...
Reproductive Toxicology, 2014
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Papers by Gerhard Weinbauer