Exercise As Cancer Prevention Medicine
from the NYTimes
Medical researchers agree that, at the very least, regular exercise can make people feel better and feel better about themselves.
There is less agreement on whether it can also prevent cancer. But for two types, the evidence is promising: breast cancer and cancer of the colon. Other cancers have not been studied, or the studies that have been done have yielded little evidence that exercise can help.
Even for breast and colon cancer, further confirmation is needed.
Adolescents feel less biological pressure to head to bed early
Sleep trigger slower in teens than children
Providence, RI – A new study by leading sleep experts finds that the "sleep pressure" rate – the biological trigger that causes sleepiness - slows down in adolescence and is one more explanation for why teens can't fall asleep until later at night.
Published in the November issue of the journal Sleep, the study suggests that as children mature, their internal, chemically-driven pressure to sleep builds up more slowly. As a result, teens aren't sleepy until later in the evening.
"We've found another part of the story – the mechanism in the brain that builds up sleep pressure is working at a different rate in adolescents than in pre-pubescent children," says co-author Mary Carskadon, PhD, director of the Bradley Hospital Sleep Laboratory and professor of psychiatry and human behavior at Brown Medical School.
Previously, numerous studies have found that as children go through puberty, they struggle to go to bed early, a phenomenon attributed to changes in their brain's internal clock mechanics. This new finding indicates that, in addition to the changes in their internal clocks, adolescents experience slower sleep pressure, which may contribute to an overall shift in teen sleep cycles.
"The results show that the adage 'early to bed, early to rise' presents a real challenge for adolescents," says Carskadon.
The study subjects were seven pre/early pubescent children, and six mature adolescents who underwent 36 hours of sleep deprivation as their brainwaves, or electroencephalograms (EEGs) were monitored. The results showed that the build-up of sleep pressure, or sleep need, during an extended period of wakefulness is slower in adolescents than in pre-teens.
This means that for teens, the pressure to sleep doesn't kick in until later in the evening compared to younger children who have faster sleep pressure rates.
"When children are little, their sleep pressure rises faster so they fall asleep early, but when it's slower, like it is for teenagers, it's harder to get to sleep," says Carskadon.
The authors purport that the shift in sleep-cycles for teenagers is simply one more way to physically prepare them for full maturation.
"We propose that the higher tolerance to prolonged waking may prepare children for adult lifestyles and for performing tasks under sleep deficits that are common in adults of modern societies," the authors conclude.
Pediatricians ignore screenings that flag hearing problems in children, new SLU research finds
Findings are published in Archives of Pediatrics and Adolescent Medicine
ST. LOUIS -- Pediatricians are not referring more than half of the children who fail hearing screenings for further tests, according to new research by a Saint Louis University physician. The study was published in the October issue of the Archives of Pediatrics and Adolescent Medicine.
"Doctors are doing tests that they're ignoring," says Donna R. Halloran, M.D., assistant professor of pediatrics at Saint Louis University School of Medicine, and a study author.
"Stop doing the test if you are not going to pay attention to it. Or, if you are going to do the test, pay attention to the results."
Halloran and her colleagues evaluated hearing screening results during 1,061 routine doctors' visits at three academic and five private practices in Alabama. They found that 10 percent of the children failed a hearing screening, which means that they missed reacting to at least one frequency sounded in either ear at the 20-decibel level. Of those children who failed the test, 59 percent received no further evaluation.
"My biggest problem is it's such a waste of money," says Halloran, who also is a SLUCare pediatrician at SSM Cardinal Glennon Children's Hospital. "It surprises me that in a litigious society we're ignoring screening results."
About 3 percent of the population has hearing impairment, Halloran says, which means the routine hearing screening picks up false positives.
However, if more than half of those who fail hearing screenings are not referred for in-depth evaluation by an audiologist, some children who have hearing problems might not get the help they need.
"At 4 years, they'll start to have some language delays that some people argue are not reversible," Halloran says. "A mild speech delay will be overlooked until they get into kindergarten. And even with severe hearing loss, huge improvements can be made with hearing aids."
While the study was conducted between 1998 and 2000, in 2003 the American Academy of Pediatrics revised its standards of hearing loss upwards – to 25 decibels, Halloran says. That's the equivalent, she says, to having 20:30 vision instead of 20:20, and likely fewer children would fail that screening.
However, the research brings a new question to light: How do doctors decide what to do when young patients have an abnormal screening result?
"The findings from this study are worrisome because physicians took no further action in more than 50 percent of the children who failed the hearing screening," Halloran says.
"Further evaluation or intervention must take place to allow children with possible hearing impairment to benefit from screening practices. Screening that does not result in action for those failing the screening wastes resources and fails to initiate necessary intervention for hearing loss."
An existing diuretic may suppress seizures in newborns
Drug targets pathways unique to the newborn brain
A diuretic drug called bumetanide may serendipitously help treat seizures in newborns, which are difficult to control with existing anticonvulsants, according to a study in the November Nature Medicine. The study findings could lead to clinical trials of bumetanide in newborns, whose immature, rapidly-developing brains are especially vulnerable to seizures. Newborns' seizures can cause long-term neurologic impairments and a tendency toward seizures later in life.
Conventional anticonvulsants – phenobarbital and benzodiazepines – are ineffective in newborns because their brains are biochemically different from adult brains, says neurologist Frances Jensen, MD, of Children's Hospital Boston, a senior investigator on the study. Jensen's team, led by postdoctoral fellow Delia Talos, PhD, collaborated with Kevin Staley and colleagues at the University of Colorado Health Sciences Center to find a treatment for seizures that would work in newborns.
The researchers knew that conventional anticonvulsants work by mimicking the action of GABA, a natural inhibitory chemical in the brain, by activating GABA receptors on the surface of brain cells. In adult nerve cells, GABA activation opens up channels that allow chloride to move into the cell. The cell thereby acquires a negative charge and becomes less excitable, inhibiting seizure activity. But in newborns, chloride is already high, and therefore activating GABA receptors causes chloride to move out of nerve cells, creating a paradoxical excitatory reaction that may actually exacerbate seizures.
To better understand this paradox, the researchers focused on two molecules that regulate cellular chloride levels: KCC2, which transports chloride out of cells, and NKCC1, which brings chloride in. Previous studies in rats had shown that adult nerve cells mostly have KCC2, making their chloride concentrations lower inside than outside. Thus, when GABA receptors are activated, chloride tends to come in, with an inhibitory effect. In newborn rats, the situation is reversed: their nerve cells mostly have NKCC1, so chloride is actively transported inside, making initial chloride concentrations very high. As a result, GABA activation causes chloride to exit the cell, with an excitatory effect.
To see if the same pattern applies in humans, Talos and colleagues at Children's Hospital Boston examined NKCC1 and KCC2 levels in brain tissue from children who had died, ranging from second-trimester fetuses to preschool-age children. Just as in rats, NKCC1 levels were high during the fetal and newborn periods, peaking one week after birth, but fell during the first year of life, approaching the low levels found in adults. Also as in rats, KCC2 levels were initially low, but rose over the first year of life.
"We found that NKCC1 is expressed unopposed in the immature brain," says Jensen. "We thought that perhaps if we blocked its inward transfer of chloride, we could get immature neurons to act like older neurons and give GABA a chance to do what it's supposed to do."
The researchers knew that the diuretic bumetanide inhibits NKCC1 activity in the kidney, and reasoned that the drug might have a similar effect in the brain, lowering chloride levels and making nerve cells responsive to GABA activation. Staley and colleagues in Colorado conducted a trial in baby rats and found that bumetanide indeed inhibited seizure activity, while phenobarbital, as in humans, worked poorly.
The study's findings are in keeping with epidemiologic studies finding that adults taking diuretics for other reasons are less likely to have seizures. Jensen's group has begun discussions about launching a clinical trial of bumetanide in newborns. Although the drug is FDA-approved and has been used in newborns for other indications, a number of safety questions will first need to be addressed before a trial can proceed.
Last year, Jensen's lab found that another FDA-approved drug, topiramate, may prevent long-term seizure disorders in newborns who suffer seizures due to oxygen starvation. This drug acts by blocking another receptor, known as the AMPA glutamate receptor, which is much more abundant in newborns' brains than adult brains (see http://www.childrenshospital.org/newsroom/Site1339/mainpageS1339P1sublevel86.html). Like bumetamide, topiramate targets proteins that are uniquely expressed in the neonatal brain.
"As we learn more about age-specific brain mechanisms, we can develop novel therapies for newborn seizures, but in the meantime, there may be things already on the shelf that we can use," Jensen says.
Updated data on novel HPV vaccine confirms efficacy in large population
Research to be presented at AACR's Frontiers in Cancer Prevention Reseach conference
Baltimore, MD – (October 31, 2005) Updated data from a study on a promising new vaccine against a pre-cancerous cervical virus shows superior efficacy in preventing cervical pre-cancers and non-invasive cervical cancer, according to a study presented today during the American Association for Cancer Research's 4th Annual Frontiers in Cancer Prevention Research meeting in Baltimore.
Final results of the phase III study, originally published in early October, confirmed the vaccine's efficacy from available combined phase II and phase III data sets, incorporating an additional 7,000 patient records as compared to the interim results. The researchers concluded from these analyses that the administration of this vaccine, known as GARDASIL, is highly effective in preventing high-grade pre-cancerous illnesses and non-invasive cervical cancers.
Of the 8,487 women who received the vaccine, none were diagnosed with high-grade cervical pre-cancers (CIN 2/3+, cervical intraepithelial neoplasia) or non-invasive cervical cancers associated with human papillomavirus (HPV) types 16 and 18. Of the 8,460 women who did not receive the vaccine, 53 such cases were diagnosed.
In the larger population analysis, which included women who may have become infected with HPV during the vaccination period or who may have violated the protocol (e.g. by missing visits, etc.), the vaccine prevented 99 percent of HPV 16 or 18-related high-grade cervical pre-cancers (1 of 9,342 pts versus 81 of 9,400 in the placebo group) with an average follow up of 25 months.
The vaccine was generally well tolerated, and the most common adverse event reported in the trial was local discomfort at the injection site.
The study is part of an ongoing phase III program involving more than 25,000 people in 33 countries. For the FUTURE II study, a prospective, randomized, double-blind, placebo-controlled study, women aged 16 to 26 years were randomized to receive a three-dose regimen of either the vaccine or placebo at Day 1, Month 2, and Month 6. The analyses evaluated the incidence of cervical pre-cancers through follow up for an average of 20 months after completion of the regimen.
HPV, particularly types 16 and 18, is the primary cause of cervical cancers and other related illnesses, infecting more than 20 million Americans. Globally, cervical cancer is among the leading cancers in women, with an estimated 470,000 new cases every year, disproportionately within the developing world, and the availability of a vaccine to prevent the disease
Studies Clarify Risk Factors for Mother-to-Child Transmission of Hepatitis C Virus
Breastfeeding does not raise the risk of mother-to-child transmission of hepatitis C virus (HCV), according to two new studies published in the December 1 issue of The Journal of Infectious Diseases, now available online.
One study found that infant girls are twice as likely to be infected as infant boys. Both studies provide new information with which to counsel pregnant women infected with HCV. Taken together, the two new studies expand upon preliminary data from smaller studies of mother-to-child transmission of HCV.
The larger of the two studies, conducted by the European Paediatric Hepatitis C Virus Network, involved 1,479 mother-and-child pairs enrolled at 33 centers in Italy, Spain, Germany, Ireland, the United Kingdom, Norway, and Sweden. The other study, by Eric E. Mast, MD, MPH, of the U.S. Centers for Disease Control and Prevention and colleagues, followed 244 infants born to infected mothers in Houston and Honolulu.
The finding of gender differences in HCV infection was reported by the European authors, who hypothesized that their result may reflect hormonal or genetic differences between men and women in susceptibility or response to infection. Other risk factors significantly associated with transmission were the time in labor (a risk factor in both studies) and use of internal fetal monitoring devices (a risk factor in the U.S. study only).
Although breastfeeding is a known risk for HIV transmission, both studies found it was not associated with transmission of HCV. The European study also found that caesarean section delivery, infant prematurity, and maternal history of injection drug use were not associated with HCV transmission.
The overall rate of transmission of the virus from infected mother to child was 6.2 percent in the European study and 3.6 percent in the U.S. study.
"Our results strongly suggest that women should not be offered an elective caesarean section or discouraged from breastfeeding on the basis of hepatitis C infection alone," said Pier-Angelo Tovo, MD, the lead author of the European study.
"Our findings support existing recommendations to avoid internal fetal monitoring and prolonged labor…in infected women," wrote the U.S. authors.
In an accompanying editorial, R. Palmer Beasley, MD, of the University of Texas at Houston, emphasized the European study's novel finding of a gender difference in transmission rates and suggested that higher HCV rates in female newborns may be due to excess mortality in infected males in utero. "Overall, the observation of higher hepatitis C virus infection rates in female infants is in accord with recent observations of similar excesses in HIV infection of female infants," Dr. Beasley said.
Could plain soap and probiotics beat hospital bugs?
Doctors might be better off washing their hands with yoghurt instead of relying on antiseptic soap-scrubbing, according to a new discussion paper by a UCL (University College London) researcher.
Scientists should investigate whether saturating the skin with 'good' bacteria would offer better protection against deadly germs, says the paper. Professor Mark Spigelman, of the UCL Centre for Infectious Diseases and International Health, is calling for a study to be set up in hospital units in which antibiotics would be banned, to explore alternative health protection measures against MRSA.
In the paper, published in the November issue of Annals of the Royal College of Surgeons, Professor Spigelman says the time has come to re-evaluate the concept of using antibiotics and scrubbing hands and wounds with antiseptic soaps. His paper outlines a six-point proposal to set up surgical hospitals which would be antibiotic-free and would instead comply with the novel standard practices being investigated.
Professor Mark Spigelman says: "Inappropriate use of antibiotics remains a major problem, despite our ever-growing understanding of how bacteria behave. For example, any student who has grown bacteria in a lab will know that they generally do not grow on top of one another. So when we wash our hands, we could actually be killing off harmless commensals to the extent that we leave space for other bacteria, such as MRSA strains, to settle.
"Perhaps we should be thinking about using probiotics and even dipping our hands after thorough washing into a solution which contains harmless bacteria, which could then colonise our skin and prevent pathogenic bacteria from settling on it.
"It must be remembered that after almost 40 years, MRSA has not become widespread except in hospitals where we use the most advanced antibiotics and most rigorous antiseptic measures. Why is this? More of the same does not seem to be working – new antibiotics and antibacterial soaps have not stopped MRSA.
"The idea may sound absurd, but I believe that a probiotic cleaning procedure is an avenue worth exploring. To overcome the current epidemic of MRSA and other bacteria, we should aim to set up a handful of hospitals where the use of antibiotics would be banned, and any patients who needed them would be transferred to an antibiotic-using hospital. Doctors from these hospitals would not be allowed to enter hospitals which use antibiotics.
"At the same time we could trial the benefits of using 'good' bacteria to saturate the skin on doctors' hands and even patients' wounds prior to surgery, to see if this would prevent the settling of pathogenic, antibiotic-resistant bacteria. For instance, a surgeon who has spent the morning repeatedly scrubbing his or her hands in an operating theatre may well have got rid of many harmless skin commensals. When the surgeon then goes to the wards, the more virulent bacteria may settle into the areas left vacant. As a first step, the surgeon could use probiotics to try and prevent this sequence of events, for example by dipping their hands into a probiotic substance such as yoghurt."
thats it for now.
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