October 1, 1997
The next time you see a news report on Russia's Mir Space Station, pay close attention. A little bit of Tulane will be on board. On Sept. 25, Tulane researchers sent up an experiment involving rat renal cells to Mir with NASA astronaut David Wolf aboard the shuttle Atlantis as part of the research performed through Tulane's new Environmental Astrobiology Center.
Tulane dedicated the center, part of the Tulane/Xavier Center for Bioenvironmental Research (CBR), on Sept. 17 at the J. Bennett Johnston Health and Environmental Research Building. Astrobiology--the study of biological science in space--covers a wide spectrum of research interests, says the center's director, Tim Hammond, an associate professor of medicine in the nephrology section at Tulane and a researcher and physician at the Veterans' Affairs (VA) Medical Center.
From investigations on why bowhead whales are dying in Alaska to developing ways of improving astronaut hydration in space, researchers already have a host of projects under way through the VA and Tulane's nephrology section.
"The center will take the CBR into a whole new field of environmental research," says John McLachlan, director of the CBR. "The genesis of this idea started with a generous gift from the Shell Oil Co. Foundation," says McLachlan of a $1-million donation awarded in 1996 (see "New lab to strengthen Tulane and Xavier ties" in the June 1996 Inside Tulane). "It supports a research and teaching facility in the CBR to house Xavier faculty and students and Tulane faculty and students."
"In the process of putting this lab together," he adds, "we were lucky to recruit Tim Hammond's group from the VA Hospital and establish, with NASA's blessing, a small center for environmental astrobiology."
The origin of the NASA connection, and much of the center's research, revolves around using microgravity, the virtual absence of gravitational force, to grow certain cells in high enough quantities for researchers to study. As a nephrologist, Hammond studies kidney disease and particularly the microscopic part of the organ called the proximal tubule, the section of the kidney involved in protein absorption.
"We're interested in the receptors for common kidney toxins in the proximal tubule," Hammond says. "The toxin we see most often is the antibiotic gentamicin." Overload of this drug can lead to complications of the kidney "and is the most common reason for prolonged hospital stays at the VA and in other hospitals," says Hammond.
To clarify the mechanism behind gentamicin's toxic nature in the kidney, Hammond looked to the recently cloned protein receptor, called megalin, that binds to the antibiotic. When megalin and gentamicin bind together, like a hand fitting into a glove, the resulting toxic effects shut down kidney function. Hammond and his colleagues set out to study the receptor with the hope of eventually developing protective drugs.
"The problem is that there is no cell culture model available that produces that receptor," Hammond says. "When we tried to grow the cells in culture, they lost their specialized features."
Hearing that NASA had a unique technique to culture cells using simulated microgravity, Hammond contacted the organization's biotechnology section and began growing kidney cells using the method.
"To our surprise and delight it worked extremely well," he says. "We got abundant production of tissue-specific proteins in the kidney and that allowed us to initiate a series of studies on the toxicity of common toxins." Hammond was intrigued by "rotating wall vessels" device used to simulate microgravity, which he playfully describes as "soup cans spinning on their sides."
The device balances gravitational force with other stresses, resulting in the closest earthbound scientists can come to simulating the absence of gravity. Contacting NASA, Hammond began a relationship with the vessel's designers: David Wolf, an astronaut mission specialist, flight surgeon and engineer, and Tom Goodwin, a project scientist at Johnson Space Center in Houston.
"We were working a great deal together and felt that the easiest way to facilitate interaction was to form a center, get a physical space and make everything a little more formal," Hammond says.
NASA, Tulane's nephrology section, the VA Medical Center and the CBR formed the Environmental Astrobiology Center and moved researchers into the Shell Research and Teaching Laboratory on the Johnston building's ground floor. Another current study to be continued in the new center is research on heavy metal toxicity in bowhead whales in the Arctic Ocean near Barrow, Alaska.
NASA's Richard Linnehan, an astronaut and veterinarian, became interested in the giant, 60-foot-long whales after hearing about cases of kidney toxicity problems and contacted Tulane nephrology section's James Kaysen, research assistant professor.
"There is a lot of cadmium naturally occurring in the Arctic Ocean, and there might be more accruing due to mining activities," Kaysen says.
Last spring, he went to Barrow to get kidney and liver tissue samples to isolate the genes that make the proteins that bind with heavy metals--the metallathionein genes. "Cadmium isn't really toxic unless it binds to metallathionein and ends up in the kidney," he adds.
Back in the lab in New Orleans, Kaysen cloned the metallothionein gene and hopes to grow more whale cells in microgravity. The challenge is harvesting the cells, since regulations permit only the native Inupiat to hunt the endangered whales, which migrate in the spring and fall. During Kaysen's recent trip, the Inupiat hunters harvested three of the whales, every part of which they used for food.
His research will examine the effects of cadmium on the whales as well as the toxic effects on the Inupiat people who eat the whales' kidneys. Other research projects at the center include minimizing astronaut dehydration in space and understanding the cause of chronic bladder inflammation in women.
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