Study suggests mice produce egg cells after birth

Shanghai scientists say they have detected germ-line cells that produce unfertilized eggs, or oocytes, in both young and old mice.

The scientists worked only with mice, but because all mammals are physiologically similar, any proof that the rodents could produce eggs after birth would encourage research to see if humans could, too.

This challenges the conventional view that women are born with all the egg cells they will produce for their entire lifetime and never generate new ones. If the Chinese team’s findings are correct, this could create a major change in fertility treatment.

Although similar theories have been made before, none have been sustainable. Earlier this month, however, the same idea relating to heart muscle cells – that they never get replaced throughout a person’s lifetime – was found incorrect by Swedish scientist Jonas Frisen.

The team, led by Kang Zou and Ji Wu of Shanghai Jiao Tong University, scanned the mice’s ovaries for cells that produce the vasa homolog protein, found only in germ-line cells. During the embryo’s formation, the cells make all the oocytes for the females‘ lifetime.

The scientists detected vasa-producing cells in the mouse ovaries, removed them and put them in laboratory glassware. Then, they were injected with a green fluorescent protein – a way to mark cells.

The researchers later injected the cells into the ovaries of another group of mice whose own eggs have been killed. When the mice mated, some of their offspring were green, suggesting that they were from the eggs produced by the injected germ-line cells.

However, other experts say that the findings are still difficult to interpret and more research must be done before the study is clinically relevant, as there are significant differences between mice and people.

(Source: nytimes.com)

Study suggests astronauts‘ muscles age in space

A new study has found that astronauts lose a significant amount of muscle mass in space.

The study, paid for by NASA and published in the April issue of The Journal of Applied Physiology, looked at nine American and Russian astronauts who spent at least six months in space and had access to various aerobic and resistance exercise machines.

The researchers measured leg and muscle volume with MRI scans, muscle performance with dynamometers, and constructed calf-muscle biopsies before and after the astronauts went to space.

After observing the astronauts‘ exercise routines using logs and videos, the researchers estimated that they averaged the equivalent of about 50 minutes of aerobic activity and 30 minutes of resistance training a day.

Despite this exercise, it was found that the astronauts lost an average of 13 percent of muscle mass and 20 to 29 percent in muscle performance.

Scott Trappe, lead author of the study, said that astronauts need to develop new modes of exercise that will provide for higher intensity, as they do not get the everyday exercise available to people on earth.

(Source: nytimes.com)

ANNA OPALKA compiled SCIENCE SCENE and can be reached at features@theaggie.org.

UC Davis researcher Gary Leisorowitz was recently awarded $900,000 to formulate a diagnostic test for ovarian cancer. The test aims to detect ovarian cancer at its preliminary stages. The grant was given by the Ovarian Cancer Research Fund.

Leisorowitz, along with fellow researcher Professor Carlito Lebrilla, has been working mostly with glycomics analysis to aid in cancer diagnosis. The glycomics analysis is used as a biomarker that would compare changes in this serum in women who have ovarian cancer versus healthy women.

“The technique for this is currently providing very promising results but the preliminary results require extensive clinical validation before it can actually be said that a new ovarian cancer blood test has been developed,” Leisorowitz said.

He said the grant money will be used to “do clinical validation of the study and to better understand the pathogenesis for these aberrant glycans that decorate glycoproteins.“

The ultimate goal of the ongoing study would be to develop a test for ovarian cancer that is more accurate than those currently available, Leisorowitz said.

The clinical evaluation involving the glycomics analysis is a very specific study.

“Our approach differs from many because we look at a special type of posttranslational modification on proteins. Glycosylation is the addition of short sugar chains (Glycans) on proteins. There are over 50 years of [research] that show the sugar chains differ in cancer [cells] versus normal [cells],” said Lebrilla, a UC Davis chemistry professor who created the glycomics technology along with the help of his lab.

Leisorowitz recognizes the concerns that come along with ovarian cancer and thus understands the urgency of developing a diagnostic test that could potentially improve overall survival in these patients.

“Ovarian cancer is the third most common gynecologic cancer that afflicts women in the U.S. Unfortunately, it is also the most deadly. Over 75 percent of women with ovarian cancer will [be living with the] advanced stage disease, and the five-year survival is only about 20 to 30 percent.

“In contrast, early stage ovarian cancer has an 80 to 90 percent five-year survival,” Leisorowitz said.

In the future, Leisorowitz and his co-researchers hope that this research can open the door to new diagnostic tests and potentially improve the understanding of ovarian cancer and the way in which it develops. They hope the research would then assist in creating therapeutic tools.

SADAF MOGHIMI can be reached at features@theaggie.org.

With springtime comes festive events like Easter and Mother’s Day, and with all the blooming flowers, a bouquet is often the gift of choice. Experts place caution on one kind of flower, however, for the beautiful plant has proven to be toxic – and often fatal – to felines.

Ingestion of even minute amounts of a lily flower or its pollen causes severe kidney damage in a cat, and without treatment, mortality rate is extremely high.

“For some reason, cats like to chew on these plants,” said Larry Cowgill, professor of medicine and epidemiology at the UC Davis Veterinary Medical Center. “The toxicity is so severe that probably half of cats exposed to lilies die. It’s just too risky to keep lily arrangements in the house.“

Experts stressed the speed and severity of the poisoning. Without treatment, the period of time between initial ingestion and death is often less than a week.

“Cats can get acute kidney failure fairly quickly, [within] 48 to 72 hours,” said Robert Poppenga, veterinary toxicologist at the UC Davis School of Veterinary Medicine. “If the kidneys don’t produce any urine, it could be two, three or four days before the animal could actually die.“

The kidneys essentially filter blood and excrete its waste products in the urine. Without these vital organs, toxins and electrolytes build up in the blood, adversely affecting the normal, homeostatic functions of the body.

“[The lily flower] damages the cells in the kidney that are responsible for normal functioning,” said Dana Farbman, spokesperson for the ASPCA animal poison control center. “The animal dies as a result because of the toxin buildup not being let out.“

According to experts, there are a number of signs and symptoms the cat will display if poisoned. They will often have a general reluctance to eat and drink, and will continually vomit. In addition, their behavior will change: The animal will become reclusive, depressed and lethargic.

Even if these signs and symptoms occur, however, lily poisoning is not necessarily the culprit. Although they can be caused by other factors, they are still serious symptoms – whether it is the result of lily poisoning or not. Poppenga stressed that the animal should still be taken to the hospital.

Experts said that treatment should begin before damage to the kidneys proceeds further.

“Once signs of kidney failure start to show themselves the prognosis for a good outcome decreases,” Farbman said. “With lily poisoning overall, prompt and aggressive care needs to be taken in order to avoid a life-threatening situation.“

Initially, treatment involves fluid administration not only to prevent dehydration, but to also test how damaged the kidneys are. If the kidneys are damaged measures are often taken.

“[Treatment] depends on whether the animal is producing any urine at all,” Poppenga said. “The animal is usually given fluid, and if the animal is not producing any urine, hemodialysis can be used. But that usually takes time and can be very expensive.“

Even though these treatments are shown to be mostly effective – given that the animal is hospitalized in a timely manner and the damage to the kidneys is not severe – there exists no antidote for the toxin. Instead, hospitalization merely re-hydrates the cat and hemodialysis takes over the job of the kidneys while these organs are weakened.

“[Treatment] supports the animal for kidney failure for animals that have a mild degree of damage,” Cowgill said. “During this time, it is hoped that the kidneys will heal themselves.“

In order to prevent such events, experts stressed that pet owners should be aware of local plants and household chemicals that can fatally wound a dog or cat if ingested.

“Just like antifreeze used to cause kidney failure in cats and dogs, people just don’t understand that lilies have this kind of serious risk to cats,” Cowgill said.

Likewise, Poppenga emphasized that it is better to err on the side of caution.

“I think it’s always important for pet owners to be aware of potential problems for their pets,” Poppenga said. “There is a lot of information online regarding this. Consult your veterinarian to avoid the products in your house that could be toxic.“

MICHAEL MILLER can be reached at features@theaggie.org.

The National Cancer Institute has awarded UC Davis researchers $1.25 million to fund a five-year project focused on identifying diagnostic biomarkers for kidney cancer. The grant will enable research that sets the groundwork for developing a new, simple test to detect kidney cancer in its early stages when it is most treatable.

Although kidney cancer accounts for just fewer than 2 percent of all cancers globally, the incidence of the disease is rising.

The five-year patient survival rate drops from 95 percent to about 5 percent if kidney cancer is diagnosed after it has metastasized to distant organs. However, there are no screening tests currently available for early detection of the disease, which is the sixth leading cause of cancer death in the U.S.

Many patients are diagnosed incidentally during screening for other kidney problems, according to Robert Weiss, a professor of nephrology at UC Davis and principal investigator for the grant.

Weiss will team up with other researchers who believe that kidney cancers produce a distinct chemical profile of metabolites – byproducts of metabolism – that can be picked out in patients‘ urine.

“We’re taking a different approach where instead of looking at genes, we’re looking at pathways that are altered [in cancer],” Weiss said.

Tumors are known to have revved up metabolisms compared to slower-growing normal tissue. The researchers speculate that, in the case of kidney cancer, cellular processes contributing to fast tumor growth will overproduce certain metabolites that show up in urine. They suspect that characteristic chemical profiles may also reflect specific mutations that give rise to the cancer.

“Kidneys are known to have active roles in body metabolism, and its excretions are readily discernible in urine,” said Oliver Fiehn, an associate professor at the UC Davis Genome Center who is advising Weiss for the project. “That’s why [kidney cancer] might be a good target for finding metabolic markers.”

The proposed study is by no means a trivial task. Urine contains thousands of metabolites, and identifying them can be technically challenging, Weiss said.

The researchers will also need to control for many factors that can affect the metabolic profile of urine samples collected from the 50 patients they plan to enroll for the study.

“If you’re looking for a specific test for [kidney] cancer, you have to control for people with kidney failure or people with some other kind of cancer because we don’t want to test for all cancers,” Weiss said.

The researchers will use chemical analysis methods to detect potential biomarkers as differences in the metabolic profiles – what they call “blips” – between patients with and without kidney cancer. Once they identify candidate metabolites in urine, the researchers will then perform a blind study with another group of patients for which kidney cancer status is unknown. The goal will be to confirm that proposed biomarkers are useful for identifying who does or does not have kidney cancer in an unbiased manner.

“We’re looking for profiles that are characteristic of kidney cancer in the stage that it’s [diagnosed], and so extrapolating backwards, we’re hoping that we’ll see [those profiles] to maybe a lesser extent [in the earlier stage],” Weiss said.

Another major goal of the project is to find markers of kidney cancer that will quickly indicate if a particular therapy is working or not.

“At a more fundamental level, biomarkers of kidney cancer may lead to mechanistic understanding that could in turn lead to new therapies or better support for patients undergoing therapy,” said Bruce Hammock, a UC Davis professor of entomology who is also on the research team.

The researchers hope that results gleaned from the project will eventually translate into a reliable urine test that doctors can conduct during routine examinations to screen for kidney cancer.

ELAINE HSIA can be reached at features@theaggie.org.