суббота, 14 января 2012 г.
How Predictable Are Urinary Tract Infections?
Kuklinski and Koduri say a urine dipstick positive for nitrites (produced by bacteria in a UTI) implies UTI, but the urine culture, which takes longer and is more expensive, is the gold standard for a positive diagnosis. If the urine dipstick could be used to diagnose a UTI, say the authors, treatment could begin immediately. They found that despite associating urine dipsticks and urine cultures positive for nitrites, 40%-50% of the UTIs would have been missed without the urine culture due to the sensitivity of the bacteria.
Although Kuklinski and Koduri couldn't conclude the urine dipstick accurately diagnosed UTI, their study indicates the urine culture is still important for diagnosis and treatment. They recommend practitioners continue to use the urine culture and offer patient education on UTI symptoms.
Predicting Urinary Tract Infections in a Urogynecology Population
Deborah Kuklinski, MS, RNC, WHNP; Sumana Koduri, MD
Urologic Nursing; February 2008
suna
The Society of Urologic Nurses and Associates is a national, non-profit professional membership association with over 3,000 members and annual revenues of $1.5 million. SUNA derives its income from membership dues (only $60), conference registration fees, exhibits, advertising, grants, and the sale of educational products.
SUNA publishes a professional, peer-reviewed bi-monthly journal (Urologic Nursing Journal) and a bi-monthly newsletter (Uro-Gram). SUNA establishes the scope and standards of urologic nursing practice and the scope and standards of advanced urologic nursing practice. SUNA provides scholarships, grants and awards to deserving nurses and other health care professionals.
SUNA supports and promotes the certification of urologic nurses and associates by providing educational preparation for the examinations offered which lead to certification in three areas.
SUNA provides a variety of opportunities for participation including local chapters, task forces and Special Interest Groups (SIGS) in five major subspecialty areas.
suna
суббота, 7 января 2012 г.
Family Lifespan Boosted By Late Motherhood
"If women in your family give birth at older ages, you may well have a chance of living longer than you would otherwise," says the study's lead author, demographer Ken R. Smith, a professor of family and consumer studies at the University of Utah. "If you have a female relative who had children after age 45, then there may be some genetic benefit in your family that will enhance your longevity."
For descendants of the Utah and Quebec pioneers studied, "you may be able to look at the ages when your female ancestors gave birth - rather than just their longevity - in estimating how long you may live," says Smith, whose study will be published online May 4 and in the June 10 print issue of the Journal of Gerontology: Biological Sciences.
The researchers examined high-quality genealogical records from the Utah Population Database at the University of Utah with its records of 1.6 million Utah Mormon pioneers and their descendants. They also used the University of Montreal's Program on Demographic History Research, which has records on 400,000 people who lived in heavily Catholic Quebec between 1608 and 1850.
Specifically, the study involved the records of 11,604 Utah men who were born between 1800 and 1869 and who had at least one sister who lived at least to age 50; and the records of 6,206 Quebec men who lived between 1670 and 1750, and had at least one sister who lived to 50 or older. The key findings:
Women who had "late fertility" - a birth at age 45 or older - were 14 percent to 17 percent less likely to die during any year after age 50 than women who did not deliver a child after age 40. That confirmed earlier studies. But those studies did not determine if the women gave birth later and lived longer because of genes or because of social and environmental factors such as good nutrition or healthy living.
Brothers who had at least three sisters, including at least one sister who gave birth at age 45 or later, were 20 percent to 22 percent less likely to die during any year after age 50 than brothers who had no "late fertile" sisters. That indicates what earlier studies did not, namely, the same genes may influence the lifespan of both sexes and women's ability to give birth at older ages.
The brothers' wives didn't have longer lives, suggesting any environmental or social factors that influence lifespan had only a weak influence, and that genes may explain why brothers lived longer when they had a sister who gave birth in her 40s.
The study didn't address how much longevity is due to genetics, but Smith says scientists believe genes account for up to 25 percent of differences in longevity.
Smith conducted the study with two other University of Utah researchers: Richard Cawthon, a research associate professor of human genetics, and demographer Geraldine Mineau, a research professor and director of population sciences at the university's Huntsman Cancer Institute, where Smith also is an investigator. Other coauthors were demographer Alain Gagnon and sociologist Ryan Mazan of the University of Western Ontario, and demographer Bertrand Desjardins, of the University of Montreal.
Good Genes Versus a Good Environment
Smith says that during the last decade, "there have been several studies that show a number of species, including humans, are able to reproduce late without medical intervention - and those females live longer." Other studies found that late menopause also is associated with women having prolonged fertility and longevity.
"There is a genetic component to longevity, especially for living to very old ages," Smith says. "The new thing here is what most evolutionary biologists long have argued: that survival and reproduction are intrinsically linked to one another. So the novel finding in this paper is discovering this link in humans before modern contraception."
But he says the link between late motherhood and longevity "could be something that is not inherited. It could be good nutrition or really good living, suggesting that if you are a healthier mom you live longer."
That is why the researchers looked at the lifespan of the brothers of women who had babies late, and of those brothers' wives. The wives are not blood relatives, so genetic factors shared by sisters and brothers wouldn't be the same in the brothers' wives.
Smith says the study focused on the longevity of brothers rather than sisters of late-fertile women because "men's own reproductive history doesn't get in the way of assessing the role of their female relatives' fertility."
The study focused on the two pioneer groups not only because of the quality of the data but because of the absence of modern birth control and an unfavorable attitude toward natural family planning methods by Mormons and Catholics. Also, a link between late fertility and lifespan is easier to observe in large families with more sisters.
Since all of those studied are now dead, the researchers could look at the full length of their fertile periods and lives. "Not many data sets could do this," Smith says.
The researchers controlled for various factors that could skew the results. For example, they excluded any individuals who did not live to at least 50 because a husband's death at a younger age would influence his wife's child-bearing.
Late Babies Linked to Longer Life for Moms and Blood Uncles
The study confirmed earlier research showing that women who have babies late tend to live longer.
Compared with women who had their last baby before age 41, Utah pioneer women who had their last baby at age 41 to 44 were 6 percent less likely to die during any given year past age 50, and Utah pioneer women who had their final birth at age 45 or older were 14 percent less likely to die during any given year after age 50.
In other words, imagine woman A had her last baby at age 35, woman B had her last baby at 42 and woman C had her last baby at 46. Then at age 52 - or any other age past 50 - woman B would be 6 percent less likely to die than woman A, and woman C would be 14 percent less likely to die than woman A.
In Quebec, slightly different age groups were analyzed. Compared with younger mothers, women who had their last child between ages 42 and 44?? were 6 percent less likely to die during any given year past age 50, and women who had their last child at age 44?? or older were 17 percent less likely to die during any given year past age 50.
By looking at the brothers of women who had children late, the study suggests the same age-slowing genes may be responsible for both prolonged fertility in women and longer lifespan in both sexes. The effects of late fertility were strongest for brothers with at least three sisters because the larger the number of sisters, the more likely it is at least one will give birth in middle age.
So in the Utah group, brothers with three or more sisters - at least one of whom gave birth at age 45 or older - were 20 percent less likely to die during any given year after age 50 than men without late-fertile sisters.
In Quebec, brothers with three or more sisters - at least one of whom gave birth at age 44?? or older - were almost 23 percent less likely to die during any single year after age 50 than men without sisters who gave birth late.
It is possible social and environmental reasons - good water, good nutrition, a healthy environment - could explain why the brothers and their late-birthing sisters had longer lives. So the researchers also examined the longevity of the brothers' wives.
They found no increase in lifespan, indicating that heredity - far more than environmental factors - played a role in the prolonged fertility and longer lives of the women, and the longer lives of their brothers.
Smith says the new findings do not conflict with one of his earlier studies finding that having larger families reduced parents' lifespan. Both findings can operate together.
Source:
Lee Siegel
University of Utah
суббота, 31 декабря 2011 г.
Kaiser Daily Women's Health Policy Report Highlights Recently Released Studies
Pregnancy & Childbirth
"Fostering International Collaboration in Birth Defects Research and Prevention: A Perspective From the International Clearinghouse for Birth Defects Surveillance and Research," American Journal of Public Health: Lorenzo Botto of CDC's National Center on Birth Defects and Developmental Disabilities and colleagues examined three methods of monitoring birth defects: an example of the "intersection of surveillance and research," an example of the "evolution from surveillance to outcome research," and an example of a public health collaboration in genetics (Botto et al., AJPH, 3/29).
"Work Activity in Pregnancy, Preventive Measures, and the Risk of Delivering a Small-for-Gestational-Age Infant," AJPH: Agathe Croteau of the Universite Laval's CHUL Research Centre and colleagues examined women in Quebec who between January 1997 and March 1999 had single live births to evaluate whether "some occupational conditions," such as an irregular daily schedule, during pregnancy increase the likelihood of delivering an infant with a low birthweight. The study concludes, "Certain occupational conditions experienced by pregnant women can increase their risk of having an [infant with a low birthweight], but preventive measures can reduce the risk" (Croteau et al., AJPH, 3/29).
"Factors Associated With the Rise in Primary Cesarean Births in the United States, 1991-2002," AJPH: Eugene Declercq of Boston University's School of Public Health and colleagues from the National Center for Health Statistics examined factors contributing to changes in rates of caesarean sections in the U.S. between 1991 and 2002. The researchers concluded that changes in c-section rates during the study period were not related to shifts in risk profiles of the pregnant women (Declercq et al., AJPH, 3/29).
"Patient Privacy and Conflicting Legal and Ethical Obligations in El Salvador: Reporting of Unlawful Abortions," AJPH: Heathe Luz McNaughton of the University of North Carolina-Chapel Hill School of Public Health and colleagues examined the possible reasons that lead El Salvadorian OB/GYNs to report women who underwent abortion despite "ethical and human rights standards" that "oblige providers to respect patients' privacy" (Luz McNaughton et al., AJPH, 3/29).
"Paternal Age as a Risk Factor for Low Birthweight," AJPH: Nancy Reichman of Robert Wood Johnson Medical School and Julien Teitler of Columbia University evaluated whether there is a connection between paternal age and low birthweight among urban U.S. residents. Reichman and Teitler -- who controlled for maternal age, demographic factors and gender -- concluded that paternal age is a risk factor that contributes to the low birthweight of an infant (Reichman/Teitler, AJPH, 3/29).
"Associations of Maternal Age- and Parity-Related Factors With Trends in Low-Birthweight Rates: United States, 1980 Through 2000," AJPH: Quanhe Yang of CDC and researchers at the University of California-Los Angeles and Emory University's Rollins School of Public Health examined how shifts in the ages of U.S. pregnant women affect birthweight trends. The authors concluded that "delayed childbearing may play an increasingly important role in low-birthweight trends" in the U.S. (Yang et al., AJPH, 4/6).
"Thrombolytic Therapy of Acute Ischemic Stroke During Pregnancy," Neurology: A. Murugappan of the Stroke and Neurological Critical Care Programs at Wayne State University School of Medicine and colleagues examined eight pregnant women whose brains were deprived of oxygen because of a blood clot or other occlusion and who then were treated with thrombolytic therapy to break up the blockage. The study concludes that, while pregnant women can be treated with thrombolytic therapy, "risks and benefits" to both the pregnant woman and the fetus "must be carefully weighed" (Murugappan et al., Neurology, March 2006).
Public Health
"Improving Birth Control Service Utilization By Offering Services Prerelease vs Postincarceration," AJPH: Jennifer Clarke of Rhode Island Hospital and colleagues examined whether providing contraceptive services within a prison compared with after inmates' release would increase female inmates' use of contraceptives. The study finds that providing contraceptives during women's incarceration is "feasible" and "greatly increases birth control initiation" compared with only providing services after their release (Clarke et al., AJPH, 3/29).
"Reproductive Health Care and Family Planning Needs Among Incarcerated Women," AJPH: Clarke and colleagues examined the "level of risk for sexually transmitted diseases ... and the productive health needs" of 484 female inmates in Rhode Island to evaluate how best to plan for their release. The women had "extremely high risks" for sexually transmitted infections and pregnancy because of inconsistent contraceptive and condom use and more than one sexual partners and had a "high prevalence" of unintended pregnancies and STIs, the study finds. The researchers concluded that female inmates need reproductive health services because the services will "benefit the women, the criminal justice systems and the communities to which the women will return" (Clarke et al., AJPH, 3/29).
"Fertility Regulation and Reproductive Health in the Millennium Development Goals: The Search for a Perfect Indicator?" AJPH: Ruth Dixon-Mueller, an independent consultant, and Adrienne Germain of the International Women's Health Coalition examined the U.N. Millennium Development Goals and found that the MDGs are missing a measurement of a woman's ability to "regulate [her] fertility safely and effectively." The study looks at three possible indicators to measure women's reproductive health: "contraceptive prevalence and total fertility; unmet need for contraception and unplanned births; and unsafe abortion and abortion mortality" and recommends that using only one of these measurements is "insufficient." The researchers concluded that a monitoring system should be incorporated into the MDGs or should exist as a "parallel effort by reporting governments and other agencies" (Dixon-Mueller/Germain, AJPH, 3/29).
"Risk for New Onset of Depression During the Menopausal Transition," Archives of General Psychiatry: Lee Cohen of Massachusetts General Hospital and Harvard Medical School and colleagues examined the relationship between menopause and the emergence of depression in women with no history of mood disorders. The study finds that women with no previous diagnosis of depression who experience the menopausal transition earlier have a higher risk of developing depression (Cohen et al., Archives of General Psychiatry, April 2006).
"Associations of Hormones and Menopausal Status With Depressed Mood in Women With No History of Depression," Archives of General Psychiatry: Ellen Freeman, a research professor at the University of Pennsylvania School of Medicine, and colleagues enrolled 231 women who were about to enter menopause and had no history of depression at time of enrollment and studied the women for eight years (Reuters Health, 4/4). The researchers evaluated the women using the Center for Epidemiological Studies of Depression scale and found that women were more than four times as likely to have a score of 16 or greater during the menopausal transition as compared with when they were premenoupausal. In addition, the study finds that women are two-and-a-half times as likely to be diagnosed with a depressive disorder during the menopausal transition compared with when they are premenoupausal (Freeman et al., Archives of General Psychiatry, April 2006).
Sexually Transmitted Infections
"Valacyclovir Therapy To Reduce Recurrent Genital Herpes in Pregnant Women," American Journal of Obstetrics and Gynecology: William Andrews of the Center for Research in Women's Health at the University of Alabama-Birmingham and colleagues examined the effect of Valtrex -- known generically as valacyclovir -- therapy among 112 pregnant women with genital herpes (Williams et al., American Journal of Obstetrics and Gynecology, March 2006). The researchers recorded no symptoms of herpes infection up to two weeks after delivery among any of the infants of the women treated with Valtrex and concluded that Valtrex therapy was safe for both pregnant women and their infants (Douglas, Reuters Health, 4/5).
"Epidemiology of HPV 16 and Cervical Cancer in Finland and the Potential Impact of Vaccination: Mathematical Modelling Analyses," PLoS Medicine: Ruanne Barnabas of the Cancer Epidemiology Unit at the University of Oxford and colleagues developed a transmission model for the most common strain of human papillomavirus -- HPV 16 -- in Finland to estimate the likelihood of virus transmission. Researchers found that HPV vaccines have the potential to reduce the incidence of cervical cancer caused by specific HPV strains. In addition, high levels of vaccine coverage over several decades, along with long-lasting vaccine protection, would have the greatest effect on the incidence of HPV type-specific cervical cancer, the researchers said (Barnabas et al., PLoS Medicine, May 2006).
"Reprinted with permission from kaisernetwork. You can view the entire Kaiser Daily Health Policy Report, search the archives, or sign up for email delivery at kaisernetwork/dailyreports/healthpolicy. The Kaiser Daily Health Policy Report is published for kaisernetwork, a free service of The Henry J. Kaiser Family Foundation . © 2005 Advisory Board Company and Kaiser Family Foundation. All rights reserved.
View drug information on Valtrex.
суббота, 24 декабря 2011 г.
Senate Panel Holds Hearing On Rape Kit Backlog
"We need to be figuring a way to get our local law enforcement up to where they need to be," Sen. Jeff Sessions (R-Ala.) said at the hearing.
Several senators called for the bolstering of a 2005 law (P.L. 108-405) designed to reduce the backlog of untested rape kits. According to Linda Fairstein, who led the Manhattan District Attorney's Sex Crimes Unit, New York's effort to test every kit has resulted in a rape arrest rate of 70%. "We need to find, identify, test and get results on every rape kit that exists in this country," she said. Witness Debbie Smith said, "Each box holds within it vital evidence that is crucial to the safety of women everywhere" (Keteyian, CBS News, 12/15).
Reprinted with kind permission from nationalpartnership. You can view the entire Daily Women's Health Policy Report, search the archives, or sign up for email delivery here. The Daily Women's Health Policy Report is a free service of the National Partnership for Women & Families, published by The Advisory Board Company.
© 2009 The Advisory Board Company. All rights reserved.
суббота, 17 декабря 2011 г.
Federal Judge Rules In Favor Of Teacher Challenging Ohio Law On Union Membership Due To Abortion-Rights Stance
The case involves Carol Katter, a Catholic teacher in the St. Mary's School District in western Ohio who opposes abortion rights. Katter said she refused to pay dues to the National Education Association because she said the union supports abortion rights. Katter sued the State Employment Relations Board after the panel ruled against her claim for a religious exemption, the Dispatch reports.
Frost in his ruling wrote that the law discriminates among religions by recognizing the Mennonite and Seventh-day Adventist objections to joining unions while denying the same right to others. "The statute further differentiates between two employees who have the same religious beliefs, are members of churches with formal doctrines against supporting labor unions, but one of the churches has recently embraced a doctrine, while the other has historically embraced it."
Frost ruled that Katter and others who opt out of unions will have to pay the equivalent of their dues to qualified nonreligious charities and will be entitled to the protections of the union. The NEA and the Ohio Education Association did not return calls for comment (Nash, Columbus Dispatch, 6/26).
"Reprinted with permission from kaisernetwork. You can view the entire Kaiser Daily Health Policy Report, search the archives, or sign up for email delivery at kaisernetwork/dailyreports/healthpolicy. The Kaiser Daily Health Policy Report is published for kaisernetwork, a free service of The Henry J. Kaiser Family Foundation . © 2005 Advisory Board Company and Kaiser Family Foundation. All rights reserved.
суббота, 10 декабря 2011 г.
HIV And The Desire To Become Pregnant
A woman's age at the time she learns of her HIV status appears to influence this decision. Women in an Ohio State University study who learned of their HIV infection when they were under age 30 were almost four times more likely to say they wanted to become pregnant than were women who were over 30 when they learned they had HIV.
Researchers say the findings point to a need for clinicians to be aware that women with HIV might be struggling with decisions about motherhood - a relatively new phenomenon accompanying the increase in HIV-positive women of childbearing age and the longer survival rates among patients who receive treatment.
"We shouldn't assume that women aren't going to become pregnant or don't want to become pregnant now that they have HIV. That's an erroneous assumption," said study co-author Julianne Serovich, professor and chair of human development and family science at Ohio State. "Clinicians should be routinely discussing pregnancy with HIV-positive women of childbearing age."
In 2005, 29.5 percent of all new reported HIV infections and 27 percent of new AIDS cases in the United States were among women, according to the Centers for Disease Control and Prevention. Twenty years earlier, only 5 percent of new AIDS cases were reported in women. HIV is the virus that causes AIDS.
The study is published in a recent issue of the journal AIDS and Behavior.
The researchers collected questionnaires about pregnancy decisions from 74 women who were participants in a larger, long-term study led by Serovich that explored women's HIV disclosure decisions and mental health. This particular line of research emerged from interviewers' observations that participants were talking about pregnancy and, in some cases, becoming pregnant. Simultaneously, health care professionals were sharing stories with researchers about the women's success in avoiding transmission of the HIV virus to their babies.
"It became obvious that this is a disease that is manageable for women," said lead study author Shonda Craft, who completed the research while she was a doctoral candidate at Ohio State.
"If a woman is 19 years old and diagnosed with HIV, she can still assume she has her whole life ahead of her. Deciding whether to have a family is part of the development process for young women, including these young women," said Craft, now an assistant professor of family social science at the University of Minnesota. "This study is about living with a chronic disease, and not just the physiological piece of that, but also the psychological and sociological factors, as well."
Women in the study were asked to quantify how influential several factors were on their decision about whether or not to become pregnant after their HIV diagnosis.
Aside from external influences, age emerged as a major factor in the choice. Nearly 40 percent of women age 30 and younger chose to become pregnant while 11 percent of the women over 30 opted for pregnancy.
The most influential external factors on women's choices against pregnancy, regardless of age, were fear of transmitting HIV to a child or other concerns about preserving their own health. Conversely, a powerful personal desire to have children was associated with a woman's choice to become pregnant.
Within the women's social network, medical personnel had the strongest influence on their decisions about pregnancy - either for or against having a baby.
Though there are no guarantees of safely conceiving and delivering a healthy baby for women with HIV, the medical community has found ways to reduce health risks for both mother and child, said Michael Brady, professor and chair of pediatrics at Ohio State and a co-investigator on the study's funding grant. Women who are HIV-positive should receive antiretroviral medications throughout their pregnancy and during labor, and their newborns should receive antiretroviral medication for the first six weeks of life. Delivery by Caesarean section also can reduce risk of transmission of the virus to the infant, but should be performed if required for the mother's health or if the mother's level of virus in the blood is high. With optimal care, the risk of transmission can be as low as 1 percent, Brady said.
There is also a risk associated with conception of the child, Brady noted. Though transmission of HIV from an infected woman to an uninfected male partner is not universal during unprotected sex, it can happen. Even if both partners are already infected with HIV, an infected male partner might transmit a new strain of HIV to his infected female partner, which can cause problems for the mother and fetus as well.
"We don't understand all of the factors that affect the risk of transmitting HIV with an individual sex act. Taking medications and lowering the viral load reduces but doesn't eliminate the risk. Some people interested in having a child may be willing to accept this risk. But there is a risk," Brady said.
One finding of the study surprised the researchers. Women who had the most negative self-image associated with their HIV status were also the most likely to want to become pregnant.
"We would have predicted that the lower the stigma, the more likely women would choose to become pregnant. We saw the exact opposite - that those with high stigma were making more choices in favor of pregnancy," Serovich said.
For some women who feel highly stigmatized by their disease, the rewards of pregnancy might offer therapeutic benefits, the researchers suggest.
"When you're pregnant, you get lots of attention, people come up to you and touch your belly. You get a shower, people do things for you. There are certainly a lot of very positive repercussions of pregnancy that may help women feel better," Serovich said.
Though much of Serovich's earlier research focused on HIV-positive men, she sees a need for a deeper examination of issues facing women who are infected.
"There hasn't been a lot of work done in this area and as women live longer and stay healthier, we need to know even more," she said. "What is clear is that women can live with this and have many options."
This study was funded by the National Institute of Mental Health.
Additional co-authors were Robin Delaney of human development and family science and Dianne Bautista of statistics, both at Ohio State.
Emily Caldwell
Source: Julianne Serovich
Ohio State University
суббота, 3 декабря 2011 г.
Immune Cell Function Can Be Suppressed By Leading Pathogen In Newborns
The UC San Diego researchers describe how GBS fools the immune system into reducing production of antibiotic molecules. "We have discovered that the bacteria have evolved to use a trick we call 'molecular mimicry,'" said Victor Nizet, MD, UC San Diego professor of pediatrics and pharmacy. "Like a wolf in sheep's clothing, GBS can enter our body without activating the immune cells that are normally programmed to kill foreign invaders."
The findings represent a collaborative effort between the laboratories of senior authors Nizet and Ajit Varki, MD, distinguished professor of medicine and cellular and molecular medicine. Varki is also co-director of the UCSD Glycobiology Research and Training Center, where the investigators have been exploring the interaction of bacterial pathogens with the innate immune system. Their most recent focus has been on the special role of Siglecs (short for sialic acid binding Ig-like lectins), members of the immunoglobulin family of antibodies.
Siglecs sense a chemical structure known as sialic acid - a sugar molecule that is abundant on the surface of all human cells - and send signals that control the gene expression and function of immune cells. Many specialized Siglecs receptors send negative signals, recognizing sialic acids as "self." These signals help keep the immune cells turned off under baseline conditions, avoiding unnecessary inflammation in the absence of infection or injury. Earlier this year, in a manuscript published in the journal Blood, the same UC San Diego team demonstrated that GBS decorates its own surface with sialic acid, closely resembling human molecules, and is thus able to bind Siglecs on immune cells, shutting down the cells' normal functions.
In the new study, the researchers discovered that GBS can also bind a human Siglecs receptor through a particular protein expressed on the bacterial surface. This is the first time a protein has been reported to functionally interact with Siglecs, and presents the possibility that additional pathogenic microbes may have evolved similar ways to manipulate the human immune system.
According to the study's lead author, Aaron Carlin, MD, PhD, when GBS proteins bind to Siglecs, it profoundly affects immune-cell function by decreasing its ability to engulf the bacteria, a process known as phagocytosis.
"The immune cells reduce their production of antibiotic molecules, allowing the GBS bacteria to survive the encounter and proliferate," said Carlin, who recently completed his doctoral studies in UC San Diego's Medical Scientist Training Program.
Knowledge of the mechanisms by which crafty pathogens engage Siglec receptors to fool the immune system may reveal new targets for medical therapy. "Blocking engagement of the Siglec could help boost the immune system and aid in clearing GBS infection in the critically ill newborn," said Nizet. "Alternatively, perhaps the bacterial molecule could be exploited as a novel treatment for human diseases involving abnormal inflammation, for example, rheumatoid arthritis."
Siglecs are among the most rapidly evolving parts of the human genome. This suggests that strong natural selection pressures are present to modify their expression, according to Varki, with pathogenic microbes likely playing a critical role.
"There are important variations in Siglec expression and function between humans and other species, among human populations, and across the age spectrum. Evidence is accumulating that Siglecs may profoundly affect susceptibility or resistance to several important infectious diseases," said Varki.
According to the UC San Diego researchers, the new study likely has broad implications for understanding the propensity of certain bacterial pathogens to produce human disease. It also explains why some individuals or groups may be more predisposed to suffer more severe outcomes than others.
Approximately 20 to 25 percent of women of childbearing age are asymptomatic carriers of GBS on their vaginal mucosal surface. Newborns can become infected with GBS that invade through the placenta to initiate infection in the womb, or during delivery by exposure to contaminated vaginal fluids. Screening of pregnant women for GBS and antibiotic prophylaxis during labor is used to reduce the risk of newborn transmission, yet it estimated that approximately 3,500 newborns still develop invasive GBS infections annually in the United States. In addition to neonatal disease, GBS is increasingly associated with serious infections in adult populations such as pregnant women, diabetics, and the elderly.
This study was financed by grants from the National Institutes of Health. Co-authors contributing to the study were Yung-Chi Chang, PhD and Charles King, PhD, of the UCSD Department of Pediatrics; Nancy Hurtado-Ziola, PhD of the UCSD Department of Cellular and Molecular Medicine, and Thomas Areschoug, PhD, and Gunnar Lindahl, PhD, of Lund University in Sweden.
Source:
Debra Kain
University of California - San Diego