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New in Physiology (page 66 of 72)
A new antigen-cloning technique may help advance efforts to develop a vaccine against melanoma and other kinds of cancer, a U.S. study suggests.
To date, scientists have had difficulty isolating and cloning antigens needed to develop cancer vaccines that directly stimulate immune system helper T-cells, which have receptors on their cell surfaces that can recognize and bind to tumor-related antigens, according to background information in a news release.
A team at the Wistar Institute in Philadelphia says it has developed a novel method to clone an antigen recognized by helper T-cells. In this study, the scientists identified and cloned a new tumor antigen called ribosomal protein L8 (RPL8) from melanoma.
They then found that a peptide of RPL8 stimulated a response in helper T-cell clones and lymphocytes in four out of nine melanoma patients but stimulated no response in cells taken from healthy people.
RPL8, which is involved in protein synthesis and is present in normal cells, is overexpressed in melanoma, breast cancer and gliomas, the most common type of brain tumor.
This new antigen-cloning technique may lead to the development of vaccines that can directly stimulate helper T-cells to fight not only these cancers, but also infectious diseases, the researchers said.
The study was published in the April 15 issue of Cancer Research.
HealthDay News, April 16, 2007
Tai chi, an exercise that features slow martial arts-like movements and meditation, significantly improves the ability of older adults' immune systems to fight the virus -- varicella zoster -- that causes shingles, a new study says.
Shingles is a painful, blistery rash. About one-third of adults over age 60 develop shingles.
The 25-week study, conducted at the University of California, Los Angeles, involved 112 people, ages 59 to 86. The researchers found that Tai chi, by itself, increased immunity against varicella zoster to a level that was comparable to having received the standard vaccine against the virus.
When a person did Tai chi and received the vaccine, the immunity against the virus reached a level normally seen in middle age, said the study, which was published in the April issue of the Journal of the American Geriatrics Society.
The study results confirm that a behavioral intervention such as Tai chi can trigger a positive, virus-specific immune response, said lead author Michael Irwin, professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA.
"These are exciting findings, because the positive results of this study also have implications for other infectious diseases, like influenza and pneumonia. Since older adults often show blunted protective responses to vaccines, this study suggests that T'ai chi is an approach that might complement and augment the efficacy of other vaccines, such as influenza," Irwin, who is also director of the UCLA Cousins Center for Psychoneuroimmunology, said in a prepared statement.
HealthDay News, 4/6/2007
The arthritis drug Humira eased symptoms of psoriasis of patients in two clinical trials and drug maker Abbott Laboratories says it will apply for U.S. and European approval to market the drug to treat the skin disease.
One study found that Humira cleared up all symptoms of psoriasis while the other study found the drug led to an 80 percent improvement in patients, Bloomberg News reported.
Symptoms of psoriasis include inflamed, scaly skin lesions that can crack and bleed. The disease affects about 125 million people worldwide.
Currently, Humira is approved to treat the immune system disorders rheumatoid arthritis, psoriatic arthritis, spinal arthritis, and Crohn's disease. The drug works by blocking the activity of a protein called TNF. Too much TNF can cause the immune system to attack healthy tissue, Bloomberg News reported.
Ohio State University researchers have found that a naturally occurring amount of antioxidants in females may be the reason that males are three times more likely to get skin cancer.
The university scientists, led by assistant professor Dr. Tatiana Oberyszyn, investigated the incidence of squamous cell cancer -- a common type of skin cancer in humans -- in a controlled experiment on laboratory mice.
According to an Ohio State University news release, the researchers exposed the animals to UVB, a type of ultraviolet light that causes the most damage to the skin. They found that the naturally occurring amount of antioxidants produced by the female mice not only protected them three times as much from squamous malignancy, but also may have caused tumors that developed in females to be smaller than those in the male mice.
"It's given us clear evidence of a biological basis for the gender bias in developing squamous cell carcinoma," Oberyszyn is quoted as saying in the news release.
The study appears in the April 1 issue of the journal Cancer Research.
HealthDay News, April 1, 2007
An anticancer gene that moonlights as a suntan gene may partly explain why people crave sunlight and even become addicted to tanning.
Scientists report that the p53 gene, which works to curb tumors, also triggers the chemical chain reaction that makes the skin tan when exposed to ultraviolet (UV) light.
The p53 gene spurs the tanning process to reduce UV damage, note the researchers, who included David Fisher, MD, PhD, of Boston's Dana-Farber Cancer Institute and Harvard Medical School.
Fisher's team found that mice without the p53 gene weren't able to tan when exposed to UV light.
And when the p53 gene triggers the tanning process, it also boosts the release of beta-endorphin, one of the body's "feel-good" chemicals.
"The induction of beta-endorphin appears to be hard-wired to the tanning pathway," Fisher says in a Cell Press news release. "This might explain addictive behaviors associated with sun-seeking or the use of tanning salons."
The study appears in Cell, along with an editorial by experts including Moshe Oren, PhD, of the molecular cell biology department at the Weizmann Institute in Rehovot, Israel.
One day, skin lotions may be able to activate p53 just enough to trigger tanning without allowing UV damage, the editorialists note.
In the Cell Press news release, Fisher says he is involved in a small biotechnology company working to develop such a product.
SOURCES: Cui, R. Cell, March 9, 2007; vol 128: pp 853-864. Oren, M. Cell, March 9, 2007; vol 128: pp 826-828. News release, Cell Press. News release, Dana-Farber Cancer Institute.
By Mirandi Hitti, WebMD, March 9, 2007
Smoking may increase wrinkles on parts of the body other than the face -- even on areas usually covered with clothes.
Cigarette smoking has long been linked to increased facial wrinkles. A new study shows that that may also be true of the rest of the body.
Yolanda Helfrich, MD, and colleagues studied 82 people at the University of Michigan at Ann Arbor's dermatology clinic.
Participants were 22-91 years old (average age: 56). Most were white; 41 had a history of smoking.
Helfrich's team interviewed participants about smoking, sun exposure, sunscreen use, tanning, and other lifestyle factors.
A medical photographer took pictures of each participant's upper inner arm.
The photos were reviewed by three judges (two dermatology residents and one medical student) who didn't know which participants were smokers.
The judges used a nine-point scale developed by Helfrich's team. A rating of 0 indicated no fine wrinkling; severe fine wrinkling yielded the maximum score of 8.
Smoking and Wrinkles
Nearly two-thirds of the participants had low wrinkle scores ranging from 0-2 points. Smokers generally had the highest scores, indicating deeper wrinkles.
The wrinkle risk was particularly strong for people who had smoked heavily for many years.
"We examined nonfacial skin that was protected from the sun, and found that the total number of packs of cigarettes smoked per day and the total years a person has smoked were linked with the amount of skin damage a person experienced," Helfrich says in a University of Michigan news release.
The study doesn't prove that smoking caused or worsened wrinkles. But the results held when the researchers took other factors, including participants' age, into account.
The study appears in the Archives of Dermatology.
By Miranda Hitti, WebMd, March 19, 2007
By Rebecca Jame Gadberry
This guru sheds light on common misunderstanding regarding these ingredients.
By Ken Klein
Learn about the state of sunscreens in the United States today and how a better understanding of them can lead to enhanced customer service for your clients.
Duct tape has many uses, but the claim that it's a cheap, effective treatment for warts is challenged by a new U.S. study in the March issue of the journal Archives of Dermatology.
A small study in 2002 suggested that duct tape helped treat warts on children and young adults. The theory is that the tape irritates the skin and prompts the immune system to attack the virus that causes warts, the Associated Press reported.
But this new study found that warts disappeared in 21 percent of 39 patients who used duct tape for seven days, compared to 22 percent of 41 patients who used moleskin, a cotton-type bandage used to protect the skin.
This new study used transparent duct tape, while the 2002 study used the better-known gray duct tape. Grey duct tape contains rubber while transparent duct tape does not, the AP reported.
"Whether or not the standard type of duct type is effective is up in the air," said study co-author Dr. Rachel Wenner of the University of Minnesota. "Theoretically, the rubber adhesive could somehow stimulate the immune system or irritate the skin in a different manner."
HealthDay News, March 20, 2007
A gene that is known to play a key role in suppressing cancer also seems to protect against sun damage while promoting a golden tan.
The revelation could one day lead to better ways to prevent skin cancer, which roughly 1 million Americans develop each year.
"This finding provides us an opportunity to look at human populations with a varied risk of developing skin cancer and start to identify precisely what is regulating the risk of developing skin cancer rather than estimating," said senior study author Dr. David Fisher, director of the melanoma program at the Dana-Farber Cancer Institute at Harvard Medical School. "Right now, we're incredibly inaccurate in identifying risk and, therefore, in ameliorating risk."
The findings are published in the March 9 issue of Cell.
People who tan easily or have darker skin are much less likely to develop melanoma, the deadliest form of skin cancer.
"The tanning response is a protective response to injury, which can prevent further injury," explained Dr. Robin Ashinoff, medical director of Dermatologic, Mohs and Laser Surgery at Hackensack University Medical Center, in New Jersey. "On the one hand, the skin is the most common organ to be affected by cancer and, in principle, it ought to be preventable because we know the carcinogen which causes it, the sun."
Still, rates of skin cancer remain high.
"That's a terrible state of affairs in 2007," Fisher said. "We really want to understand the impact of ultraviolet radiation on the skin and what is the molecular cascade that is occurring downstream."
Six months ago, Fisher and his team published a paper documenting the fact that keratinocytes -- cells closer to the surface of the skin -- react to sun exposure. Previously, it had been thought that pigment-producing melanocytes played this role.
Once keratinocytes are exposed to rays from the sun, they produce melanocyte-stimulating hormone (MSH), a growth factor which binds to the pigment cells (melanocytes) and stimulates them to produce pigment.
Differences in the MSH receptor explain differences in ability to tan. Redheads, for example, have a variant which doesn't respond at all to MSH, explaining why the Nicole Kidmans of this world don't turn a tawny bronze.
Fisher and his colleagues still didn't know, however, what happened within keratinocytes to stimulate MSH production.
"We knew that ultraviolet radiation causes MSH to be induced," Fisher said. "How is the ultraviolet radiation doing that? What is perceiving the radiation and translating that signaling into making more MSH?"
The key happens to be the tumor-suppressor gene known as p53, which is induced in almost every keratinocyte of human skin samples within an hour of being exposed to the sun's ultraviolet rays. "That activity is completely regulated by this protein," Fisher said.
The finding is biologically plausible, experts said.
"It makes sense that most skin cancers and cancers, for that matter, have mutations in the p53 because it functions to protect us. It basically causes abnormal cells to be killed or die, and regulates all sorts of pathways that protect us," Ashinoff said. "It's not surprising that something that would protect us would also stimulate mechanisms in the skin known for protecting us."
"Knowing this, we can now identify exactly where we would like to interfere with the risk," Fisher added. "Knowing that p53 is part of this process allows us to potentially identify drugs that might be able to restore this response at different steps, depending on where the person might need it, where their block is."
HealthDay News, March 8, 2007 By Amanda Gardner