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U.S. Food and
Drug Administration
FDA Consumer magazine
September-October 2001
Table
of Contents
by Linda Bren
In a field in a quiet suburban Maryland neighborhood, a cow grazes with her calf. Within the walls of a large concrete building, pigs eagerly devour their food, letting out occasional grunts. And in another building, silver-colored salmon swim in large tanks equipped with lighting timed to simulate daylight and darkness.
This bucolic setting just a few miles from the White House and the Baltimore-Washington, D.C., corridor is actually the busy hub of the Food and Drug Administration's veterinary research program. Here, at the Center for Veterinary Medicine's (CVM) Office of Research, scientists of all types--microbiologists, biochemists, toxicologists, pharmacologists, and geneticists--do the research necessary to support many of the FDA's regulatory decisions. Their work helps ensure the safety of our food supply and the safety and effectiveness of animal drugs.
The Office of Research--a 160-acre complex of laboratories, offices, animal buildings, and pastures--is also one of the FDA's many training grounds for student interns who are on their way toward becoming doctors and scientists.
Every year the FDA's internship programs bring hundreds of students out of the classroom and into the real-life setting of a regulatory agency. Coming from colleges and universities across the United States and around the world, these future scientists and administrators get valuable hands-on experience working in every FDA center and office.
The internships, which last anywhere from several weeks to a year, are awarded to students pursuing careers in biology, microbiology, pharmacology, toxicology, epidemiology, human and veterinary medicine, regulatory science, and even communications and finance. These interns arrive with the latest theories and techniques, and leave with the first-hand experience and qualified judgment that will enrich them throughout their future careers.
Brandon Dominguez knows all about farm animals. Growing up on a small farm outside of Dallas, he fed them, groomed them, and treated them when they were ill. He helped a pregnant sow deliver her piglets, and he kept watch over newborn foals late into the night. He also spent the last three years training in Texas A&M University's animal science program.
But what this 21-year-old student didn't learn on the farm or in school is how human and animal drugs are regulated and the science behind the regulatory decisions. For that, Dominguez traveled 1,500 miles from his home in Texas to work at the FDA as a student intern.
He could have worked at a local veterinary hospital, as he's done in previous summers. "But I wanted to get more experience with the government aspects of veterinary medicine," says Dominguez, "to see their research programs, and get a better understanding of the regulatory process."
Dominguez is one of about a dozen students who participate each year in "Windows to Research," CVM's summer intern program. These fledgling scientists work with FDA researchers on such projects as detecting antibiotic-resistant bacteria in animals and determining the levels of drugs transmitted from nursing mothers to infants.
"The intent of the program is to encourage students, especially minorities, to go into the field of science," says Woodrow M. Knight, Ph.D., scientific adviser for CVM's Windows to Research program and director of the division of biometrics and production drugs. "We want them to leave with a good feeling about the FDA to pass back to their community," says Knight, "and we encourage students to think about future employment with CVM."
Working alongside FDA pharmacologists and animal scientists, Dominguez learns about the transfer of drugs from a nursing mother to her infant. The "cow-calf model," a project supported by the FDA's Office of Women's Health, helps Dominguez understand the importance of drug accumulation and elimination rates in determining safety.
Why is it a "cow-calf" and not a "mother-child" study? Because data on how drugs taken by a human mother might affect her breast-fed infant are very limited, says Alberto Chiesa, D.V.M., Ph.D., visiting scientist and lead researcher on the cow-calf project. There are difficulties inherent in frequently drawing blood samples from infants and taking test samples of the mother's milk. An animal model, such as this one, enables this research to be performed.
Although using a cow to simulate a human mother may not be the most flattering comparison, there are similarities between the two, says Pamela Chamberlain, D.V.M., Ph.D., lead developer of the cow-calf model. Both are pregnant for nine months, and both can produce milk for about the same length of time. In addition, both human mothers and cows secrete colostrum (a substance high in protein and antibodies), which gradually changes to milk over the course of a few days after giving birth.
To determine the levels of a drug transferred from the cow to her calf through milk, scientists first inject the cow with the drug being tested. After she is milked several days later, the milk is fed to her offspring. Intensive blood and milk sampling reveal the drug levels. By monitoring the drug levels in the plasma of the cow and also in the calf, the study team can determine how much of the drug will accumulate in the calf. They will also be able to compare the time required to completely eliminate the drug from the cow and from the calf.
"This model provides valuable information," says Jurgen von Bredow, Ph.D., pharmacologist and researcher on the cow-calf project, "because it may mean that human mothers may be able to take certain drugs and still continue to nurse their newborn infants."
Anti-depressants, anti-convulsants to treat epilepsy, and the antibiotic ciprofloxacin to treat urinary tract infections are just some of the drugs being tested with the model.
Another area being studied by CVM's interns focuses on one of the FDA's most important, and challenging, tasks--protecting the public from antibiotic-resistant bacteria.
The use of some antimicrobials (substances to kill or weaken bacteria, viruses, fungi, or parasites) in livestock and poultry has been shown to cause the development of antibiotic-resistant bacteria, such as Campylobacter, in these animals. People who then consume the animals are at risk of becoming infected with bacteria that current antibiotics can't easily kill.
Antibiotic-resistant bacteria can pose a serious health problem. Antibiotics that were once effective have become less effective against certain common types of bacteria due in part to overuse. As a result, strains of bacteria resistant to all but the strongest antibiotics are being seen more often by physicians and public health laboratories.
Campylobacter, for example, is the most common bacterial cause of diarrheal illness in the United States, according to the Centers for Disease Control and Prevention. Most of the more than 2 million Americans (1 percent of the population) estimated to be infected with Campylobacter each year will recover without any specific treatment. But severe cases are treated with an antibiotic--and sometimes the drug doesn't work because the bacterial strain has become resistant. Campylobacter can be life-threatening in people with weakened immune systems.
In addition to their ability to develop resistance to antibiotics, bacteria are capable of becoming resistant to formaldehyde, organic acids, and other antimicrobials. Some of these antimicrobials are used in human and animal foods to fight Salmonella, molds, or other microorganisms that cause disease or spoilage. Recent research indicates that certain kinds of bacteria fight the effects of formaldehyde and other antimicrobials in some of the same ways they fight the effects of antibiotics.
CVM scientists are conducting research to determine whether or not the use of formaldehyde, organic acids, and other antimicrobials in animal feeds can trigger the development of antibiotic-resistant bacteria.
Student intern Allissa Hosten, a senior in the pre-med program at Xavier University in New Orleans, has spent the last three summers with CVM researching antibiotic resistance. She has developed protocols for and conducted experiments on sodium benzoate. Antimicrobials like sodium benzoate and other salts of benzoic acid are commonly used as preservatives in human and animal foods and drinks.
"The outcome of the experiments will be very useful to the agency," says Henry Ekperigin, D.V.M., Ph.D., a biologist in CVM and principal investigator on the research project. "It may affect how we regulate antimicrobials to ensure a more judicious use of the substances in human and animal foods."
"It's a very exciting project," says Hosten. "It's amazing that antimicrobials put in foods, drinks, and health products like toothpaste, hand creams, and soaps could cause bacteria to develop resistance or cross-resistance to commonly used antibiotics."
Three years ago, Haile Yancy interned with CVM for the summer. Today, while continuing his studies toward a Ph.D., Yancy is one of many scientists at the FDA working to keep from American shores the serious health problem now plaguing Europe: bovine spongiform encephalopathy (BSE), commonly called "mad cow disease."
Researchers believe that the fatal disease BSE is spread when cows are fed a diet that contains a high-protein supplement made from the remnants of mammals such as sheep and cows. This protein, known as mammalian meat-and-bone meal (MBM), may be contaminated with the agent that causes BSE.
To prevent the spread of BSE in the United States, the FDA has banned feeding mammalian MBM to cows. To help enforce the ban, the FDA must be able to accurately detect the presence of MBM in processed cow feed.
Current tests that detect MBM also detect milk and blood--they cannot distinguish the prohibited MBM from the allowable milk and blood. (Feed containing milk and blood is allowed because these products have shown no evidence of posing the risk of transmitting BSE.)
Yancy is designing a test to detect bovine MBM and to distinguish it from milk and blood. Other CVM scientists are working on tests to detect MBM from other animal species. These tests will allow CVM to check samples of cow feed from processing facilities to ensure that the feed does not contain the prohibited MBM.
What concerns public health experts is the possibility that BSE can--and has--crossed over into people who eat BSE-contaminated beef. BSE has been linked to about 100 human deaths in Europe from a rare brain malady called new variant Creutzfeldt-Jakob disease, or vCJD.
By preventing cows from getting BSE, the untreatable and fatal vCJD may also be prevented.
Americans have nearly doubled their consumption of farm-raised fish over the past 35 years, says Renate Reimschuessel, V.M.D., Ph.D., director of CVM's aquatic research program.
Aquaculture, the farming of water creatures such as fish, mollusks, and crustaceans, as well as aquatic plants, is becoming an increasingly important source of protein-rich food for human consumption. As the number of aquaculture facilities grows, so does the need to assure that farmed fish are high in quality and safe for people to eat. Drugs for treating fish diseases need to be safe and effective and must not harm plants, microorganisms or other sea creatures not targeted by the drugs. CVM is doing aquaculture research to meet these needs.
One of these research areas is the study of fish tuberculosis (TB). A disease caused by the bacterium Mycobacteria marinum, fish TB attacks the internal organs and can kill fish within a matter of weeks. CVM is examining mutants of the fish TB bacteria to learn more about how they infect fish and to develop vaccines to prevent the spread of this fish disease.
The TB that infects people, once the leading cause of death in the United States, began to decline in the 1940s with the introduction of effective antibiotic drugs to treat it. But the CDC now reports the number of cases to be rising, and TB has re-emerged as a serious public health problem. Since fish TB is very similar to human TB, fish vaccine research may uncover important information useful for developing a human TB vaccine.
Reimschuessel describes aquaculture medicine as a "specialty in its infancy," and CVM welcomes veterinary interns interested in this vital area of fish farming and aquatic animal research.
The summer intern program is only one of the FDA's mechanisms for training future scientists. Another is the "clerkship" program, which allows graduate students to spend part of the school year experiencing the FDA's regulatory process first-hand.
Like the summer intern programs, clerkship programs are offered throughout the FDA, allowing students to work in the areas most relevant to their fields of study.
CVM has a three-week clerkship program for students in their senior year of veterinary medical school. Open to veterinary schools nationwide, the program recruits students through the Center for Government and Corporate Veterinary Medicine (CGCVM), a program of the Virginia-Maryland Regional College of Veterinary Medicine (VMRCVM).
Schools rely on clerkship programs to provide students with a broad understanding of all aspects of a student's field of study. "Veterinary schools, like all professional schools, are constantly inundated with new information," says Peter Loizeaux, D.V.M., deputy director of the CGCVM, "and not all aspects of the profession can be taught in an academic setting."
The FDA is one of over 100 government and corporate organizations that work with the VMRCVM to help train veterinary students and allow them to see alternatives to private veterinary practice. "It really opens their eyes to career opportunities they may not have considered," says Loizeaux. About 70 percent of veterinarians are in private practice; 30 percent are in the government and corporate arena and that number is steadily increasing.
In CVM's clerkship program, managers involve the students in discussions and decision-making, says Steven Vaughn, D.V.M., a scientific adviser for the program and director of the division of therapeutic drugs for food animals. "It gives them a sense of some of the issues facing CVM and how we go about trying to deal with those issues. It also gives them a flavor of the political environment working in Washington."
FDA scientists reap benefits, too. They get the latest information and concepts coming out of colleges. "Students have new information on current research, theories being bandied about, and leads on experts and who is working on what," says Vaughn.
Each student is assigned a project to complete in the three-week period. Although three weeks may seem a short time to make a significant contribution, a student's project can make a difference to the agency, says Vaughn. One student researched three different syndromes of flexibacteriosis, a disease in fish that are raised as food. "Her work enabled us to define study protocols to demonstrate that a drug was effective against the disease and to tell the sponsor how to proceed with their drug development efforts," says Vaughn.
That former student, Joan Gotthardt, D.V.M., now leads the CVM's aquaculture drugs team.
Gotthardt had left her 11-year federal government career and a scientific position where she supervised 37 people to attend veterinary school. "When I went off to vet school, I thought I wanted to go into private practice," says Gotthardt. But as she was finishing school, she pursued a job opportunity at the FDA. "I have not looked back," she says. "I think what we do here is extremely important and worthwhile."
Terri Dudis, D.V.M., of Elkwood, Va., is one former CVM clerkship student who did go into private practice. Dudis, formerly a "content and complacent middle-level manager" at the U.S. Department of Transportation, traded in her 20 years of government service for a career in veterinary medicine. Leaving her job and her 100-acre horse farm, she moved to Blacksburg, Va., to attend VMRCVM.
Today, Dudis and her business partner travel through the countryside of Virginia in their 26-foot mobile veterinary clinic, equipped with a surgical suite, laboratory, x-ray machine, and darkroom. "There were some bumps in the road in setting up a new business," says Dudis, "and I'm working really hard, but it's a wonderful path I chose."
Whether their sights are set on private practice or a government or corporate job, students can profit from CVM's clerkship program, says Vaughn. "Whichever path they choose, working with CVM helps them understand that even though we're a small organization, the impact of our decisions is nationwide and has great importance."
The FDA offers internships to undergraduate, graduate, and professional students (for example, those completing Ph.D. program requirements). The programs are available to U.S. and some international students, including minorities and students with disabilities.
The FDA internship programs help students develop valuable skills and work experience that enrich their education and make them more employable upon graduation. Students can realistically test their career objectives, heighten their awareness of careers at the FDA, build a work history for their résumés, and earn money.
In turn, the FDA gets a qualified source of temporary help on projects, a means to evaluate potential job candidates, and an opportunity to hear new ideas and support the growth of scientific talent.
"It's a win-win situation for the student, FDA, and society," says Judy Blumenthal, Ph.D., an FDA personnel staffing specialist.
For more information on the Center for Veterinary Medicine's intern program, contact Bessie Cook, manager of CVM's Equal Employment Opportunity office, at 301-827-4587.
For information on the many other intern programs throughout the FDA, contact personnel staffing specialist Marge Dexter at 301-827-4080.
--L.B
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