Claas Mehnert

Learn More
OBJECTIVE To investigate sperm DNA damage in relation to fertilization and pregnancy. DESIGN Prospective study. SETTING The Institute of Reproductive Medicine, Giessen, Germany. PATIENT(S) Semen collected from 249 patients attending the IVF program. MAIN OUTCOME MEASURE(S) The percentage of terminal deoxynucleotidyl transferase-mediated dUDP(More)
Despite the ever-increasing knowledge of the fertilization process, there is still a need for better understanding of the causes of sperm DNA fragmentation and its impact on fertilization and pregnancy. For this reason, human sperm DNA fragmentation was investigated by means of the terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling(More)
OBJECTIVE To investigate whether there is an impact of different sources of reactive oxygen species (ROS) on sperm functions. DESIGN Prospective study. SETTING Patients at the Center for Dermatology and Andrology, Giessen, Germany. PATIENT(S) Semen collected from 63 randomly collected patients attending the IVF unit of the University of Giessen,(More)
BACKGROUND Failures in expression of zona proteins correlate to subfertility in animals. Low expression of the zona proteins by the growing human oocyte may indicate reduced developmental potential. Therefore, we non-invasively analysed the thickness and the structure of the zona pellucida (ZP) of human oocytes with respect to embryo fate after ICSI. (More)
Disturbed spindle assembly increases risks of chromosome mal-segregation. Non-invasive polarization microscopy (PolScope) was employed in two centres to assess spindle integrity for the first time quantitatively in human oocytes from consenting patients undergoing intracytoplasmic sperm injection (ICSI) with respect to pronuclear (PN) score after(More)
Purpose : The presence of a clear half-moon-like zone of cytoplasm in oocytes is called “halo effect.” The prognostic value of this effect is not yet determined. Aligned nucleoli in pronuclei (PN) represent a further polarization phenomenon and a marker for implantation potential. Aim of the prospective study was to evaluate the influence of the halo effect(More)
Investigators are divided about the limits of tolerable ambient temperatures and air humidities, even under equal boundary conditions. In 266 climatic chamber experiments, mostly lasting 4 h, 13 young healthy men were exposed to combinations of ambient temperature (20 to 55 degrees C) and relative humidity (5 to 97%) at an air velocity of 0.3 m.s-1. They(More)
The vitality of spermatozoa used for intracytoplasmic sperm injection (ICSI) is a crucial factor for fertilization, establishment and outcome of a pregnancy in assisted reproductive technique cycles. The sperm origin may also be a limiting factor, although little is known about this issue. It is known that the motility of injected spermatozoa and their(More)
In order to evaluate the aclimation of Chenopodium seedlings to different quantum fluence rates of R and BL, kinetics of Rubisco capacity, Chl content and chloroplast structure were studied. Under monochromatic light photoreceptors are stimulated selectively and their influence on biosynthetis capacities during chloroplast development can be studied. R(More)