TUESDAY, July 15 (HealthDay News) -- A new imaging technique, based on an engineered version of the common cold virus, may help doctors detect the spread of prostate cancer to the lymph nodes earlier.

This, in turn, could help guide more effective treatment decisions, said the authors of a study published in the July 11 edition of Nature Medicine.

"It would represent a treatment advance in patients for whom outcome is not good," study senior author Dr. Lily Wu, a researcher at UCLA's Jonsson Cancer Center, said in a university news release. "This would help improve the prognosis for these patients by letting us find and treat these metastases early. If we can catch the cancer before it invades other organs, we have a better chance to change the outcomes for these patients."

Patients whose prostate cancer has traveled to their lymph nodes are more likely to have a recurrence. Finding these tiny metastases in the pelvic lymph nodes is key to making future treatment decisions, yet it is also supremely difficult to do with conventional imaging techniques.

Wu and her colleagues engineered a common cold virus armed with a specific "genetic payload" to travel directly to lymph nodes in mice and to express its payload only in prostate cells.

The payload consists of a protein that can be picked up on PET scans.

Wu and her colleagues next want to combine the imaging technique with treatment, so that a drug contained in the genetic payload could kill the traveling tumor cells.

"I think this is very exciting for many reasons," said Wu. "We now know we can reach these prostate cancer metastases at an earlier stage than before, and we know we can deliver genes to those cancer cells that produce proteins that can be imaged by PET. Now we will find out how effective this genetic toxic payload is in preventing further spread of the cancer to other vital organs."

More information

Visit the National Cancer Institute for more on prostate cancer.

WEDNESDAY, July 9 (HealthDay News) -- Diabetes and being over- or underweight can have a negative effect on male fertility.

That's the conclusion of two reports to be presented July 9 at the annual conference of the European Society of Human Reproduction & Embryology, in Barcelona, Spain.

While semen samples from diabetics look normal under the microscope, a closer examination revealed DNA damage, Dr. Con Mallidis, of Queen's University in Belfast, Northern Ireland, said in a news release issued by the conference sponsors.

"Sperm RNA was significantly altered, and many of the changes we observed are in RNA transcripts involved in DNA repair," he said. "And comparison with a database of men of proven fertility confirmed our findings. Diabetics have a significant decrease in their ability to repair sperm DNA, and once this is damaged, it cannot be restored."

Sperm DNA quality is known to be tied to decreased embryo quality, low embryo implantation rates, higher miscarriage rates and some serious childhood diseases, including cancers.

"We found a class of compounds known as advanced glycation end products (AGEs) in the male reproductive tract. These are formed as the result of glycation (the addition of sugar)," Mallidis said, "and accumulate during normal aging. They are dependent on lifestyle, diet, smoking, etc., and in many diabetic complications are centrally implicated in DNA damage. We believe that they play a similar role in the male reproductive system."

The researchers plan to now determine how AGEs cause and contribute to DNA damage.

Obesity, which often plays a factor in diabetes, and being too thin, was also found to cause problems with sperm. In a separate study, scientists found that men with a higher body mass index (BMI, a ratio of weight to height) had less seminal fluid and more abnormal sperm.

The findings showed that men with an optimal BMI of 20 to 25 had higher levels of normal sperm than those who were either overweight or underweight. They also had higher semen volume.

The researchers did not look at DNA damage in the sperm, though.

"Our findings were quite independent of any other factors," scheduled presenter A. Ghiyath Shayeb, from the University of Aberdeen, in Scotland, said in the news release from the conference, "and seem to suggest that men who are trying for a baby with their partners should first try to achieve an ideal body weight."

"Adopting a healthy lifestyle, a balanced diet, and regular exercise will, in the vast majority of cases, lead to a normal BMI," he said. "We are pleased to be able to add improved semen quality to the long list of benefits that we know are the result of an optimal body weight."

More information

The American Urological Association has more about male infertility  .