Health News
Genetic links could unlock clues to leading cause of blindness
GAINESVILLE, Fla. - Age-related macular degeneration is the leading cause of blindness in older adults, yet researchers are still in the dark about many of the factors that cause this incurable disease.
But new insight from University of Florida and German researchers about a genetic link between rhesus monkeys with macular degeneration and humans could unlock secrets about the earliest stages of the disease, when severe vision loss could still be stopped.
The researchers pinpointed a chromosome region and genetic markers for macular degeneration in humans and rhesus monkeys, findings recently published in the online edition of the journal Experimental Eye Research. Linking the disease in monkeys to the disease in humans allows researchers to study how it progresses in the animals, which could lead to better treatments and even a cure.
"Stopping the development of the disease is something the monkeys will help us do that we can't do with humans," said William W. Dawson, Ph.D., a UF professor of ophthalmology and physiology and a co-author of the study. "This is a big step forward in dealing with the disease."
The researchers studied seven genetic sites in the monkeys that correspond to human chromosomes linked to macular disease. One of those areas, the findings confirm, contains genes that predict age-related macular degeneration in humans and rhesus monkeys. Dawson and other researchers have suspected for years that the disease was very similar in humans and monkeys, but these findings finally establish that. This discovery, he said, will allow researchers to delve deeper into what causes the disease and could be the first step toward repairing the genetic defects linked to it.
According to the National Eye Institute, nearly 2 million Americans have advanced age-related macular degeneration, a disease that develops when a small, light-detecting part of the retina called the macula breaks down. Seven million more Americans have an intermediate form of the disease, and millions more are expected to develop it within the next 15 years.
The disease causes nodule-like specks to build up in the eye, chipping away central vision over time. But Dawson said most people don't even realize something is wrong until they detect changes in their vision. The disease can be controlled, but there is no known way to reverse the vision loss it causes.
Knowing more about the earliest predictors of macular degeneration could help doctors treat the disease before extensive vision loss occurs and may even prevent it in some people. The early risks associated with macular degeneration have been difficult for researchers to study in humans, and as a result, doctors know little about this aspect of the disease, Dawson said.
"It's difficult to follow closely the aging of a human over a specific period of time," he said. "People wouldn't tolerate a controlled (living) environment for weeks and years."
One of the biggest problems researchers have faced is determining how much of a role genetics plays versus lifestyle and environmental factors such as blue light, part of the spectrum of natural visible light. Frequent exposure to blue light rays has been linked to macular degeneration. If the disease is going to be treated early, Dawson said researchers must know the significance of these factors.
Aside from studying early environmental risks, the next step for researchers is to map the specific genes at work, said Dawson, who worked on the study with German geneticist Jorg Schmidtke. But because more than one gene is likely involved, this task will not be easy, Dawson said.
Johanna M. Seddon, M.D., a Harvard Medical School associate professor and director of the epidemiology unit of the Massachusetts Eye and Ear Infirmary, said studies conducted on 840 human twins have shown that genetics plays a significant role but not the only role. Even diet plays a big part, she said. Her own research with the National Eye Institute has shown that taking certain vitamins and minerals can reduce the risk of developing the disease by 25 percent over five years.
"With the increasing number of people living beyond the age of 85, it heightens the importance of this disease and the concern about (what will happen) if we don't come up with a better way to treat this," she said.
That's where Dawson thinks the monkeys can help. They age three to four times faster than humans, making it easier to track the progression of the disease. The monkeys also can remain in a controlled environment to test nongenetic factors, and their families can be studied more extensively.
Although most rhesus monkeys never show signs of macular degeneration, between 30 percent and 70 percent of the monkeys Dawson's team studied do. That's because these primates are the descendents of 50 monkeys brought to live on a Puerto Rican island just before World War II. The free-ranging monkeys on the island have multiplied to near 1,500, but because the rhesus monkeys are not native to the area, they could mate only with each other. This inbreeding has predisposed the monkeys to various genetic diseases, such as age-related macular degeneration.
Unlike most other animals, a rhesus monkey's eyes have the same complex structure as a human eye, making them a model study subject. They're so similar, he said he sometimes slips images of rhesus monkey eyes into presentations for medical residents to see if anyone notices the difference.
"I haven't been caught yet," he said. "Only the most expert would detect the differences."
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Legendary medical school dean dies
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GAINESVILLE, Fla. - Dr. Hugh M. "Smiley" Hill, the former associate dean for student and alumni affairs for the University of Florida College of Medicine and a beloved legend among alumni, died Sunday
(7/31) in his Gainesville home. He was 81.
"He was a legend, a true legend," said Dr. Robert Watson, senior associate dean for educational affairs in the College of Medicine. "He was like the spirit of the place."
Dr. Hill, who earned the nickname Smiley while a student at Davidson College in Davidson, N.C., earned a reputation as a one-of-a-kind doctor and teacher who supported students and earned their trust during his 42 years at UF.
He joined the UF faculty in 1959 and within two years had earned the college's Outstanding Clinical Teacher award, an honor he received 12 times during his career.
To many alumni, the name Dr. Smiley Hill is synonymous with UF's College of Medicine. He spoke to students at orientation, during their first days as medical students. And except for the inaugural 1960 graduating class, he placed the ceremonial hood on every graduating doctor at UF until he retired in 2001. Dr. Hill also administered the Hippocratic Oath to every graduating class between 1966 and 2001.
"He knew every graduate and actually remembered almost all of them," said Dr. Kenneth Berns, director of the UF Genetics Institute and former dean of the College of Medicine. "He embodies the kind of spirit you like to see around the school of medicine.
"Every medical school needs someone like Smiley Hill."
But Dr. Hill almost never became a doctor, let alone a teacher of doctors. If the young Dr. Hill had his way he would have become a wrestler. A high school injury, however, knocked Dr. Hill out of the sport he loved and World War II led him into a career he never imagined.
During the war, Dr. Hill was chosen to receive training to be a surgical technician. He treated troops wounded during the Battle of the Bulge and risked his life to save an injured soldier from drowning, an action that earned him the Soldier's Medal of Heroism. His war experiences also sparked a lifelong love of medicine.
After the war, Dr. Hill finished his studies at Davidson College and in 1948, he entered medical school at Johns Hopkins University, where he also completed his residency.
Dr. Hill originally planned to pursue private practice in obstetrics and gynecology, but decided instead to take a position at the University of North Carolina at Chapel Hill in 1957. Students recognized Dr. Hill's talent quickly and honored him with his first teaching award.
He left Chapel Hill in 1959 for the UF College of Medicine, just three years after it opened. Four years later, he was promoted to assistant dean for student affairs. He was promoted again in 1973 to associate dean for student and alumni affairs.
At UF, Dr. Hill's commitment to medical students surfaced quickly. Students honored him with the first Hippocratic Award for Teaching Excellence in 1969. He received this award three more times during his career here. Students even named a new award for him in 1970.
He also delivered many of his students' children and was a godfather to three of them.
Dr. Hill was a member of numerous societies, including the American Board of Obstetrics and Gynecology, the American Medical Association and the Johns Hopkins Medical and Surgical Association. He also served as vice president of the Alumni Association of the Johns Hopkins College of Medicine and published articles in scientific journals such as the Southern Medical Journal and the American Journal of Obstetrics and Gynecology.
But throughout his career, those who knew him say it was the students he treasured most.
"He was like a combination of teacher and friend," said Watson who will give the eulogy at Hill's funeral Wednesday. "You don't find that too often."
Dr. Hill is survived by his wife, Ann Lazonby Hill, of Gainesville; and daughter, Grace, of Washington D.C.
Funeral services for Dr. Hill will be held at 11 a.m. Wednesday (8/3) at Holy Trinity Episcopal Church, 100 N.E. 1st St., Gainesville.
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