Final Word

Study Yields Possible Breakthrough in AIDS Treatment

An opportunistic pathogen that often affects patients with acquired immunodeficiency syndrome (AIDS) is actually present in the body before the onset of the disease and may represent a common parasite of healthy humans, as well as several species of macaque monkeys. That was the conclusion of a Major Qualifying Project by Daniel R. Hebert '97 who plans a career in veterinary medicine.

This startling discovery could have a major impact on the treatment of AIDS patients and others whose immune systems are compromised by illness. Hebert, who received his bachelor of science degree in biotechnology in May and will work toward a Doctor of Veterinary Medicine degree at Tufts University School of Veterinary Medicine, investigated the presence of microsporidia in the macaque colony at the New England Regional Primate Research Center in Southboro, Mass. The center, which opened in 1966, is affiliated with Harvard Medical School and is part of the Regional Primate Research Centers Program established by Congress in 1959. Its mission is to conduct basic and applied biomedical research aimed at solving human health and societal problems.

Microsporidia are parasites that exist as latent spores until they infect a host cell, usually within the ocular, pulmonary, muscular and intestinal systems. One species, Enterocytozoon bieneusi, is the major cause of chronic diarrhea and inflammation of the bile ducts and gall bladder in individuals with AIDS and other immuno-suppressed patients.

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"(Herbert's research) identified a chronic parasit that may be the cause of many unexplained cases of gastritis, enteritis, chronic diarrhea, and other digestive problems." - Professor Daniel Gibson

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Hebert worked with Keith G. Mansfield, D.V.M., who had previously used new molecular diagnostic techniques to locate the parasite within the macaque colony. His faculty advisor was Daniel G. Gibson, assistant professor of biology and biotechnology. Hebert, the first WPI student to complete a project at the primate center, was one of two students to receive a Provost's MQP Award from the Biology and Biotechnology Department this year. His work was also nominated for the university's Sigma Xi Research Award.

"This really is a breakthrough in gastrointestinal medicine, as well as AIDS research," says Gibson. "It identified a chronic parasite that may be the cause of many unexplained cases of gastritis, enteritis, chronic diarrhea, and other digestive problems. Here is a pathogen that can wreak havoc on the intestines, but is seldom detected because it resides elsewhere - in the ducts of the liver. This is as important as the discovery that many ulcers are caused by a bacterium, helicobacter pylori, rather than by hypersecretion of stomach acid."

Hebert used a technique called Southern blotting to detect the presence of microsporidia. The procedure involved immobilizing DNA to detect certain sequences. The DNA was transferred from a gel medium to a nylon membrane, which was exposed to a nucleic acid probe for E. bieneusi. Hebert was able to identify the parasite in 22 of 145 normal rhesus macaques and 15 of 42 macaques infected with Simian Immunodeficiency Virus. Once the positive animals were identified, bile and tissue samples were taken to study the location of infection. Persistence studies indicated that the parasite lived for 7-11 months; prior to the study there had been no indication that microsporidians were chronic inhabitants of healthy animals.

"Daniel's contribution to our research effort to elucidate and characterize the pathogenesis of E. bieneusi in rhesus macaques has proven invaluable to the progress of the study," says Mansfield. "His work here will aid the understanding of E. bieneusi in humans and eventually add to efforts to prevent and treat the debilitating condition the parasite causes in AIDS patients."

"In the future," says Hebert, "new steps in AIDS treatment could include screening for E. bieneusi at the onset of HIV infection. Once an effective cure for the parasite can be found, it can be administered to these patients and prevent much of the discomfort and disease that AIDS patients experience toward the end of their illness."

Bonnie Gelbwasser

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Multidisciplinary Project Takes First Step Toward Fully Motorized Prosthesis

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From left, recent graduates Nicole Robert, Jason Wening and Colleen Fox.

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Today, there is no such thing as a fully motorized, user-actuated shoulder prosthesis. But tomorrow there may well be, thanks to the ingenuity of three recent WPI graduates.

For their Major Qualifying Project, Colleen Fox, an electrical engineering major from Fairbanks, Alaska, Nicole Robert, an engineering physics major from Webster, Mass., and Jason Wening, a mathematical sciences major from Jefferson City, Mo., set for themselves an especially challenging goal: to develop a prototype electronic control unit that will allow an amputee to simultaneously execute motions in more than one joint of a motorized prosthesis.

Each student brought to the project his or her special area of expertise. In addition, Wening, a double leg amputee (see "Swimming Against the Odds," Spring 1995 WPI Journal), provided insights that only the physically challenged can offer. "Our project began a process that we hope will result in the development of a shoulder prosthesis that will give the amputee the tools he or she needs to be self-sufficient," he says.

During the first phase of the project, the students established the design parameters for the control unit by modeling the forces involved in moving a prosthetic arm. They learned how long it takes for the arm to accelerate, the torque changes required to retain constant angular velocity, the predictability of starting and stopping accuracy, and the possibility of overshooting.

"During the second phase, we built the electronic control unit," Fox says. "We used a motion algorithm based on the models we developed in the first phase. The algorithm transforms input signals into output signals that drive the motors of the prosthesis."

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"Our project began a process that we hope will give the amputee the tools he or she needs to be self-sufficient." - Jason Wening '97

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The group used three motors to model the motion of the prosthesis: two to control shoulder flexibility and one to control elbow flexibility. "We used a double arm-driven pendulum to simulate two joints and a single arm-driven pendulum to simulate one joint of the prosthesis," explains Robert.

As an added challenge, they had to consider the fact that the motors put out a certain torque in order to move the arm in specific patterns. They ultimately designed a motion control system to include a low-power device that is compact in size and weight - one that has the ability to change the limb's velocity or to stop it at any time in any location.

The students emphasize that their project is just a first step in the development of a motorized prosthesis. Their recommendations for the future include developing more sophisticated motion algorithms and creating lightweight motor and battery systems. "We hope our efforts will enable the physically challenged to enjoy a better quality of life," they say.

The project, sponsored by Liberty Mutual Research Center (where Ted Clancy '83 is WPI's principal MQP contact), received WPI's Provost's MQP Award from both the Electrical and Computer Engineering and Physics departments. It was advised by Fred Looft, professor of electrical and computer engineering, Van Bluemel, professor of physics, and Paul Davis, professor of mathematical sciences.

Ruth Trask