Researchers to develop dietary agents to reduce risk of cataracts for astronauts

Oct 5 2004

Two researchers in the School of Kinesiology at The University of Western Ontario are looking at ways to make space travel safer for astronauts and improve life on Earth as well.

Each researcher has been awarded a Space Life Sciences grant from the Canadian Space Agency (CSA). Western is the only university to receive two grants this year from the CSA under their space biological sciences program.

Project: Developing Dietary Agents to Reduce Risk of Cataracts for Astronauts, Jet Crews, and Nuclear Cleanup Workers ($298,232 in funding over four years); Researcher: John Trevithick, Kinesiology professor and Biochemistry professor emeritus

Astronauts are at increased risk of cataracts because of space radiation. In fact, it is estimated during a long space flight to Mars and back, about one quarter of the crew would become blind because of space radiation-induced cataracts. Other groups which are at increased risk are jet crews, radiation workers and radiation accident cleanup workers.

Trevithick will be looking at ways to reduce this risk. The results will reveal whether eye lens damage is already discernible within minutes after exposure to radiation, and whether it becomes greater after 24 hours of exposure. In a recent study, Trevithick and his team showed vitamin E could effectively reduce lens damage induced by neutron radiation. Other antioxidants and plant juices and extracts (vegetables and herbs) will also be tested for reduction of cataract risk.

“The prospect of a cataract developing during prolonged stays on the space station, in high earth orbit or moon stations, or in deep space voyages such as the contemplated manned Mars mission is a major source of concern,” says Trevithick. “Unlike bacterial infections, which can be treated by antibiotics, cataract is potentially incapacitating because of the resulting blindness, since the treatment is cataract surgery and replacement of the natural lens with a plastic intraocular lens. This cannot be done easily in the space environment, requiring a skilled surgeon and sterile operating room, and would not be feasible during a return journey from Mars.”

Project: Bed Rest Deconditioning and Central Autonomic Control ($323,800 in funding over four years); Researcher: Kevin Shoemaker, Kinesiology professor and Scientist, Lawson Health Research Institute

Changes in the neural control of cardiovascular functions such as blood pressure and heart rate, occur rapidly in microgravity situations, such as space flight. In addition to short-term problems associated with blood pressure control and exercise tolerance, these changes may have far-reaching pathological effects in long-term space flight.

Although these changes in nervous system function develop very rapidly, it has yet to be determined why autonomic control is affected by microgravity and therefore how to avoid these effects. Shoemaker feels microgravity causes changes in the functional organization of forebrain and brainstem autonomic centres that normally restrict sympathetic nerve activity (SNA) and that these changes are independent of blood volume changes.

Using the head-down bed rest model of microgravity that causes shifts in blood volume distribution similar to those that occur in space, Shoemaker and his colleagues will examine how individuals adapt to the lack of gravity (a process called deconditioning) through changes in affects in brainstem autonomic centres and how this relates to changes in SNA and narrowing of the blood vessels in limbs. They will use functional magnetic resonance imaging (fMRI) to measure brainstem activity, and microneurography, a procedure in which a small needle is placed in a nerve just below the knee, to measure nerve signals traveling from the brain to the blood vessels. Shoemaker’s research group is the only one in the world combining these techniques to examine the fundamental basis of autonomic deconditioning.

“In many individuals, overall SNA increases during real or simulated microgravity and a similar pattern is observed in aging and/or obese people, as well as in many diseases that affect the cardiovascular system (such as diabetes, hypertension, heart failure, etc.). In fact, chronically elevated baseline SNA is considered an important risk factor in the development of cardiovascular disease,” says Shoemaker. “Thus, understanding mechanisms affecting SNA control in microgravity has a direct impact on risk assessment and countermeasure development for chronic diseases in long-term space flight as well as for those remaining on Earth.”

Collaborators on this project include David Cechetto, Schulich School of Medicine (Faculty of Medicine & Dentistry) professor; Richard Hughson, University of Waterloo professor; and Robert Petrella, professor in the Schulich School of Medicine (Faculty of Medicine & Dentistry) and the School of Kinesiology at Western, and Scientist at Lawson. The Lawson Health Research Institute has provided support for the project.