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New in Physiology (page 56 of 63)
By Diana L. Howard, PhD
Teach your clients about the three biochemical reactions that cause aging skin.
U.S. researchers say they've spotted a key immune system dysfunction in patients with melanoma skin cancer.
A team at Stanford University School of Medicine, in California, found that the immune cells in most melanoma patients fail to respond properly to a molecule called interferon, which normally activates the immune system. This failure to respond to interferon means that the immune cells don't fight off melanoma.
The findings, published in the May issue of the journal Public Library of Science-Medicine, could help in the development of new treatments for melanoma.
Melanoma will kill about 16 percent of the 47,700 people in the United States expected to be diagnosed with this form of skin cancer this year.
These findings help explain why a common melanoma treatment involving prolonged exposure to interferon sometimes helps melanoma patients, said senior author Dr. Peter Lee, associate professor of medicine.
"Doctors knew it worked in some people but didn't know why," Lee said in a prepared statement. This study suggests that prolonged interferon treatment may work by overcoming the immune system's inability to respond to interferon.
Previous research has found that cancer patients often have immune system problems, but, until now, scientists didn't know which genes or pathways were at the root of the trouble. Identification of this interferon response disruption may boost efforts to develop vaccines for different types of cancer, the Stanford researchers said.
"We think this is a dominant way that immune dysfunction occurs in people with cancer," Lee said
HealthDay News, May 14, 2007
People who unwind with a cup of tea every night may have a lower risk of two common forms of skin cancer, new research suggests.
In a study of nearly 2,200 adults, researchers found that tea drinkers had a lower risk of developing squamous cell or basal cell carcinoma, the two most common forms of skin cancer.
Men and women who had ever been regular tea drinkers -- having one or more cups a day -- were 20 percent to 30 percent less likely to develop the cancers than those who didn't drink tea.
The effect was even stronger among study participants who'd been tea fans for decades, as well as those who regularly had at least two cups a day, according to findings published in the Journal of the American Academy of Dermatology.
However, the findings do not mean it's okay to bake in the sun as long as you have a cup of tea afterward. The researchers found no evidence that tea drinking lowered skin cancer risk in people who'd accumulated painful sunburns in the past.
Nor did the study look at the relationship between tea drinking and malignant melanoma, the least common but most deadly form of skin cancer.
Still, the findings support the theory that tea antioxidants may limit the damage UV radiation inflicts on the skin, according to the study authors, led by Dr. Judy R. Rees of Dartmouth Medical School in Lebanon, New Hampshire.
In particular, a tea antioxidant known as EGCG has been shown to reduce burning on UV-exposed skin.
The current findings are based on interviews with 770 New Hampshire residents with basal cell carcinoma, 696 with squamous cell carcinoma, and 715 cancer-free men and women the same age.
Tea consumption was linked to a lower skin cancer risk, even with factors such as age, skin type and history of severe burns considered. However, tea drinkers who'd suffered multiple painful burns in the past did not have a lower risk of skin cancer.
It's possible, the researchers explain, that the antioxidants in tea are enough to limit skin damage caused by moderate sun exposure, but not the "more extreme" effects of sun exposure, such as cancer-promoting damage to the DNA in skin cells.
SOURCE: Journal of the American Academy of Dermatology, May 2007.
HealthDay News, May 4, 2007
Sun worshippers won't want to hear it, but a new study says the best way to protect against cancer-causing ultraviolet rays is to avoid direct sunlight and wear protective clothing to keep exposure to a minimum.
Sunscreens are a poor second choice, but they're better than nothing, said the Swiss dermatologists who did the study.
The findings take on added urgency for residents of the northern hemisphere, where summer is approaching with its promise of long, lazy days spent at the beach or other outdoor play spots.
"Wearing sun-protective clothes and a hat and reducing sun exposure to a minimum should be preferred to sunscreens," Dr. Stephan Lautenschlager, of the Outpatient Clinic of Dermatology at Triemli Hospital in Zurich, wrote in the May 3 online edition of The Lancet.
But, this advice is felt to be "unacceptable in our global, outdoor society and sunscreens could become the predominant mode of sun protection for various societal reasons, for example healthiness of a tan, relaxation in the sun," the study authors added. "Nevertheless, sunscreens should not be abused in an attempt to increase time in the sun to a maximum."
One expert agrees with the recommendation.
"I am a proponent of the approach advocated by the [American] Cancer Society," said Dr. Martin Weinstock, a professor of dermatology at Brown University and chairman of the American Cancer Society's skin cancer advisory group. "It's called Slip-Slop-Slap. Slip on a shirt, slop on sunscreen, slap on a hat. That's the way to be safe during outdoor activities."
According to Lautenschlager's group, the type of clothing you wear can make a big difference in sun protection factor (SPF). For example, tightly woven, thick garments made of denim, wool or polyester offer the best protection, while cotton, linen and acetate are much less effective, they noted.
In terms of sunscreens, there are two kinds -- inorganic and organic. Inorganic sunscreens work by scattering UV light using zinc or titanium oxides. This type of sunscreen is well tolerated by the skin and produces few allergic effects. It is recommended for children, the study authors said.
Organic sunscreens absorb the UV rays, and are made up of complex organic molecules that are "photoprotective." Organic screens should be put on 15 to 30 minutes before going out in the sun.
And waterproof or water-resistant sunscreens should be used to reduce the need for reapplication after swimming followed by toweling, friction with clothing or sand, and sweating, Lautenschlager's group noted.
Weinstock thinks that SPF factor is the most important consideration when choosing a sunscreen. "I recommend SPF 30 or greater," he said.
Lautenschlager's group warned that while studies have found that sunscreens protect against acute UV skin damage and nonmelanoma skin cancers, it's not clear whether they help protect against melanoma, the most dangerous form of skin cancer.
"The population has to be advised how to best make use of sunscreens," the authors wrote. "The application of a liberal quantity of sunscreen is, by far, the most important factor for effectiveness of the sunscreen, followed by the uniformity of application and the specific absorption spectrum of the agent used."
Dr. Doris Day, a dermatologist at Lenox Hill Hospital in New York City, offers another safety rule to minimize your exposure to UV rays.
"There is a nice rule -- called the shadow rule -- that is very useful," Day said in a statement. "The shorter your shadow, the more dangerous the rays of the sun. So, for example, at noon when the sun is highest, you have little to no shadow, and that is the best time to try to stay indoors or in the shade."
Skin cancer -- including melanoma and nonmelanoma malignancies -- is the most common of all cancers, accounting for about half of all cancers. An estimated one million cases of nonmelanoma skin cancers are diagnosed annually in the United States. Most are basal cell -- about 800,000 to 900,000. Squamous cell cancer occurs less often -- perhaps 200,000 to 300,000 cases annually. People do not often die of these cancers. About 1,000 to 2,000 people die of nonmelanoma skin cancer each year in the United States, according to the American Cancer Society.
Melanoma, on the other hand, causes most skin cancer deaths, even though it accounts for just 3 percent of all skin cancer cases. The American Cancer Society estimates there will be 59,940 new cases of melanoma in the United States this year, and about 8,110 people will die of the disease.
HealthDay News, May 3, 2006.
The American Cancer Society this week launched a major new cancer research effort that aims to enroll 500,000 people.
According to the society, the study may be the "last best chance" to do large-scale research in the United States on genetic, lifestyle and environmental factors that cause and prevent cancer.
The Cancer Prevention Study 3 (CPS-3) will seek a geographically and ethnically diverse group of women and men, aged 30 to 65, who have never been diagnosed with cancer. The participants will be tracked for 20 or more years.
"There are no U.S. studies on the horizon positioned to take advantage of rapidly developing new knowledge and technologies over the coming decades, except CPS-3," study leader Eugenia E. Calle, managing director of analytic epidemiology at the American Cancer Society, said in a prepared statement.
"This type of study involves hundreds of thousands of people, with diverse backgrounds, followed for many years, with collection of biological specimens and assessments of dietary, lifestyle and environmental exposures. It also requires active follow-up to discover if and when study participants develop cancer," Calle said.
She noted that large studies of up to a million people are being conducted in a number of countries in Europe and Asia. Many countries are able to conduct such large studies because they have national health-care systems that record information about patients' visits.
"Another important factor is that people in other countries are often willing to be enrolled in a study, historically a serious challenge in the U.S.," Calle said.
Enrollment in CPS-3 will take place at 64 of the 4,800 Relay for Life cancer research fundraising events taking place across the United States in 2007, and will continue at certain Relay for Life events through 2011.
Data collected during CPS-3 will build on information collected from a series of American Cancer Society studies dating back to the 1950s.
Getting melanoma diagnosed by a dermatologist rather than a non-specialist could boost a patient's odds for long-term survival, a new study finds.
Researchers at Emory University School of Medicine in Atlanta studied 1,467 patients with melanoma diagnosed by a dermatologist and 553 melanoma patients diagnosed by a non-dermatologist.
On average, tumors diagnosed by dermatologists were thinner than those diagnosed by non-dermatologists -- 0.86 millimeters vs. 1 millimeter thick. When a melanoma tumor is still relatively thin (less than 1 millimeter), patients have a 90 percent cure rate.
Patients diagnosed by a dermatologist also had better survival rates.
"The two-year and five-year survival rates were 86.5 percent and 73.9 percent for the dermatologist group compared with 78.8 percent and 68.7 percent for the non-dermatologist group," the study authors wrote.
"These results suggest that increasing access to dermatologists, particularly for older patients who have higher rates of melanoma, may represent one approach to improving melanoma-related health outcomes from a health policy perspective," they concluded.
The study appears in the April issue of the journal Archives of Dermatology.
Melanoma is the most serious type of skin cancer, and can be fatal. Each year in the United States, more than 53,600 people learn they have the disease. In some parts of the world, especially Western countries, melanoma is becoming more common every year. In the United States, for example, the percentage of people who develop melanoma has more than doubled in the past 30 years, according to the National Cancer Institute.
When millions of U.S. women tossed out their prescriptions for hormone replacement therapy in 2002, the rates of breast cancer started dropping almost immediately, U.S. researchers reported Wednesday.
Their findings coincided with an early-release report from the U.K. that showed women who took hormone replacement therapy (HRT) after menopause were 20 percent more likely to develop ovarian cancer or die from it than postmenopausal women who never took HRT.
The breast cancer report, published in the April 19 issue of the New England Journal of Medicine, looked at the incidence of breast cancer both before and after the news broke from the long-term Women's Health Initiative (WHI) study that HRT might be more damaging than helpful to a woman's health. Between 2001 and 2004, it shows, the overall incidence of breast cancer went down by 8.6 percent in postmenopausal women.
The U.K. study, published online Wednesday by The Lancet, looked at the long-running Million Women Study and determined that 1,000 additional women died from ovarian cancer between 1991 and 2005 because they were using HRT, and that 1,300 extra cases of ovarian cancer were diagnosed in the same period.
The researchers, from the Cancer Research UK Epidemiology Unit in Oxford, also found that after women stopped taking HRT, their risk of ovarian cancer returned to the same level as those who never used HRT.
For the U.S. study, experts suspect that HRT may have been fueling some breast cancers because that decline began soon after many women stopped using HRT.
"From 1975 to 2000, breast cancer incidence increased rather dramatically. While part of that increase was clearly due to the introduction of screening mammography, once you take out that effect, there is still a rather astounding increase of 30 percent," said Donald Berry, chairman of the department of biostatistics at the University of Texas M.D. Anderson Cancer Center in Houston.
"While there have been a number of theories put forward to explain the increase, it now looks like some of that increase is due to the use of HRT," Berry said. "When women stopped using HRT, it looked kind of like a market correction and the numbers went back down."
Initially, it appeared as if combination estrogen-progestin hormone replacement therapy was the answer to many ills. Researchers hoped that HRT would lower the risk of such serious illnesses as heart disease and dementia.
However, the WHI study, which included more than 16,000 postmenopausal women, was stopped early in May 2002 because HRT was increasing the risk of coronary disease, stroke and blood clots.
After the WHI trial was halted, many women stopped taking hormones. In fact, the use of HRT had dropped by 38 percent in the United States by the end of 2002. In 2001, 61 million prescriptions were written for hormone replacement therapy. In 2002, there were about 47 million prescriptions. By 2003, that number had fallen to 27 million, and by 2004 just 21 million, the study authors noted.
The rate of breast cancer started dropping soon after the WHI results in 2002, according to the new study.
Between 2001 -- the last full year of combination HRT use -- and 2004, rates of breast cancer in the United States dropped by 8.6 percent in postmenopausal women. The rates of estrogen receptor-positive breast cancer -- those cancers known to be fueled by the hormone estrogen -- dropped by 14.7 percent in women between the ages of 50 and 69. Yet, rates of estrogen receptor-negative cancers dropped only 1.7 percent in the same time period, which further suggests that stopping HRT played a role in the decline.
"HRT is probably not something that causes cancer; it probably just fuels existing cancers," explained Berry. "If you feed it, it grows, and if you stop feeding it, it stops growing."
Berry said the Emory researchers looked at other potential causes for the decline in breast cancer rates, including whether fewer women were getting screening mammograms to detect tumors. The researchers also checked for environmental factors and the use of breast cancer drugs such as tamoxifen and raloxifene. But none of these factors had changed significantly enough to cause such a drop in breast cancer rates, the study authors said.
The breast cancer rates leveled off by 2004, to rates not seen since 1987, the study authors said.
"Overall, this is very encouraging news," said Dr. Julia Smith, director of the New York University Cancer Institute Breast Cancer Screening and Prevention Program in New York City.
However, Smith said she'd like to know if this drop will affect survival rates in the future. "Have these cancers been eliminated, or are they just below our level of detection now, but will rise up again?" she asked.
Both Berry and Smith pointed out that if a woman is suffering through menopausal symptoms, such as hot flashes, short-term use of hormone replacement therapy is likely safe.
"You can give low-dose HRT for short periods of time for women who really have a quality-of-life issue," Smith said. She added that individual risk needs to be assessed on a case-by-case basis, but even some women at high risk of breast cancer may be able to use HRT for short-term relief.
"It doesn't make sense to do something in the name of prevention and protection -- (withholding HRT) -- that ends up hurting the person," Smith said.
Berry said: "If you're taking HRT for long-term health effects, it's not worth it. But, if you're taking HRT for menopausal symptoms and it works for you, it's probably a reasonable thing to continue. I'd stop it occasionally to see if the hot flashes are still there, but short-term use for a year or two probably won't affect your risk in the long run."
By Serena Gordon, HealthDay News, April 18, 2007
A new U.S. survey found that more than half of athletic trainers said they've treated an athlete for a skin infection caused by the antibiotic-resistant "superbug" called methicillin-resistant Staphylococcus aureus (MRSA) bacteria.
MRSA infections were once seen almost exclusively in ill and immunocompromised hospital patients, but they have become increasingly common in otherwise healthy people over the past decade, according to background information in a news release about the survey.
While MRSA infections typically aren't fatal, they can cause skin abscesses that require surgical draining, and the infections are likely to be resistant to first-line antibiotics. In some cases, MRSA can cause serious and potentially fatal problems such as pneumonia, bloodstream infections and flesh-eating disease.
This Web-based survey of 364 certified athletic trainers found that 53 percent said they'd treated MRSA skin infections in athletes. Of the infections treated: 86 percent were in males and 35 percent were in females; 65 percent were in football players; 21 percent in basketball players; and 20 percent were in wrestlers.
The infections typically occurred in: the lower leg (38 percent); forearm (31 percent); and the knee (29 percent).
Athletes may be at increased risk for MRSA infection because it can be spread into cuts and scrapes during contact sports, as well as from shared items such as towels.
"Given that these infections could potentially become serious, it's important for athletic trainers to be aware of the signs and symptoms of MRSA infections and to treat them appropriately, as well as educate athletes about them," Kristin Brinsley-Rainisch, a health scientist at the U.S. Centers for Disease Control and Prevention, said in a prepared statement.
The survey was presented Saturday at the annual scientific session of the Society for Healthcare Epidemiology of America in Baltimore.
HealthDay News, April 14, 2007
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