Friday, May 25, 2007

We conclude that a significant proportion of infertile men have elevated levels of DNA damage in the ejaculated spermatozoa

Andrology, Vol 21, Issue 1 33-44, Copyright © 2000 by The American Society of Andrology



DNA integrity in human spermatozoa: relationships with semen quality
D. S. Irvine, J. P. Twigg, E. L. Gordon, N. Fulton, P. A. Milne and R. J. Aitken
Centre for Reproductive Biology, Edinburgh, Scotland.

The literature contains conflicting evidence regarding the existence of DNA damage in spermatozoa from infertile male patients. To examine this phenomenon, we have studied ejaculated spermatozoa from normozoospermic semen donors and from a group of the unselected male partners of couples attending an infertility clinic for initial investigation. Classical semen analysis according to World Health Organization (WHO) guidelines was undertaken with computer-assisted sperm analysis (CASA). Spermatozoa were prepared by sequential washing and centrifugation and were analyzed for DNA fragmentation using three assays: 1) a single-cell gel electrophoresis (comet) assay, 2) in situ nick translation with prior chemical decondensation (ISNT-decondensed), and 3) in situ nick translation without prior chemical decondensation (ISNT-condensed). In addition, reactive oxygen species (ROS) generation by spermatozoa was measured, and seminal plasma was analyzed for its total reactive antioxidant potential (TRAP). When the donor and patient groups were compared, the latter had lower levels of semen quality and higher levels of DNA damage, which was particularly apparent using the comet assay. Highly significant negative correlations were observed between DNA fragmentation, detected by all three assays, and semen quality, particularly sperm concentration. In addition, multiple regression analysis indicated that other attributes of semen quality, such as sperm movement and ROS generation, were also related to DNA damage. We conclude that a significant proportion of infertile men have elevated levels of DNA damage in their ejaculated spermatozoa.

Also ASRM on Introcytoplasmic Sperm Injection


Scientists shed new light on male infertility
Thu May 31, 2007 10:05AM EDT

HONG KONG (Reuters) - Scientists in Hong Kong and China have identified for the first time a protein in sperm from humans and from mice that could be responsible for many unexplained cases of male infertility.

Defective versions of the protein, called epithelial ion channel, have previously been reported to be responsible for female infertility.

Writing in the latest issue of the Proceedings of National Academy of Sciences journal, the researchers said they detected the protein in sperm samples from mice and human subjects.

"(The protein) is involved in the transport of bicarbonate, which is required for sperm activation in order to fertilize the egg. If you have a defect in this (protein), then fertilization capacity of the sperm will be impaired or reduced," Chan Hsiao Chang, physiology professor at the Chinese University in Hong Kong, said in a telephone interview on Thursday.

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Experiments showed that sperm taken from mutant mice with defective versions of the protein had far lower fertility than sperm taken from normal mice, the researchers said.

The discovery would help doctors more accurately diagnose and explain many cases of male infertility that have so far gone unexplained.

"For many people, they are infertile, but they don't know why, so diagnosis would be the immediate advantage," Chan said.

Between 8 percent and 12 percent of couples with women of childbearing age -- or between 50 and 80 million people -- are infertile globally, according to the World Health Organisation.

Half of infertile couples fail to reproduce because of problems with male fertility.



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