Recruiting thousands of patients to collect health data for genetic clues to disease is expensive and time consuming. But that arduous process of collecting data for genetic studies could be faster and cheaper by instead mining patient data that already exists in electronic medical records, according to new Northwestern Medicine research. In the study, researchers were able to cull patient information in electronic medical records from routine doctors' visits at five national sites that all used different brands of medical record software. The information allowed researchers to accurately identify patients with five kinds of diseases or health conditions – type 2 diabetes, dementia, peripheral arterial disease, cataracts and cardiac conduction.
"The hard part of doing genetic studies has been identifying enough people to get meaningful results," said lead investigator Abel Kho, M.D., an assistant professor of medicine at Northwestern University Feinberg School of Medicine and a physician at Northwestern Memorial Hospital. "Now we've shown you can do it using data that's already been collected in electronic medical records and can rapidly generate large groups of patients."
The paper will be published April 20 in Science Translational Medicine.
To identify the diseases, Kho and colleagues searched the records using a series of criteria such as medications, diagnoses and laboratory tests. They then tested their results against the gold standard – review by physicians. The physicians confirmed the results, Kho said. The electronic health records allowed researchers to identify patients' diseases with 73 to 98 percent accuracy.
The researchers also were able to reproduce previous genetic findings from prospective studies using the electronic medical records. The five institutions that participated in the study collected genetic samples for research. Patients agreed to the use of their records for studies.
Sequencing individuals' genomes is becoming faster and cheaper. It soon may be possible to include patients' genomes in their medical records, Kho noted. This would create a bountiful resource for genetic research.
"With permission from patients, you could search electronic health records at not just five sites but 25 or 100 different sites and identify 10,000 or 100,000 patients with diabetes, for example," Kho said.
The larger the group of patients for genetic studies, the better the ability to detect rarer affects of the genes and the more detailed genetic sequences that cause a person to develop a disease.
The study also showed across-the-board weaknesses in institutions' electronic medical records. The institutions didn't do a good job of capturing race and ethnicity, smoking status and family history, all which are important areas of study, Kho said. "It shows we need to focus our efforts to use electronic medical records more meaningfully," he added.
**Source: Northwestern University
21 April 2011
Los alimentos protectores del corazón
Alimentos protectores del corazón. Una de las principales causas de muerte son las enfermedades cardiovasculares ; por ello es importante que incluyas en tu dieta ciertos alimentos beneficiosos para tu corazón y tu sistema cardiocirculatorio.
La avena es rica en ácidos grasos omega 3, acido fólico y potasio; es muy rica en fibra y ayuda a bajar los niveles de LDL o colesterol malo evitando que las arterias se taponen. Los copos de avena con un lácteo, unos frutos rojos y una o dos piezas de fruta constituyen una opción sana y equilibrada de desayuno para todas las edades.
La avena es rica en ácidos grasos omega 3, acido fólico y potasio; es muy rica en fibra y ayuda a bajar los niveles de LDL o colesterol malo evitando que las arterias se taponen. Los copos de avena con un lácteo, unos frutos rojos y una o dos piezas de fruta constituyen una opción sana y equilibrada de desayuno para todas las edades.
El salmón es un alimento rico en ácidos grasos omega 3, ayuda a reducir la presión arterial y cuidar las arterias; es recomendable consumirlo al menos dos veces por semana, para reducir el riesgo de infarto; también puedes elegir sardinas o atún.
El aguacate aporta ácidos grasos insaturados y contribuye a disminuir el colesterol malo y aumentar el colesterol bueno, el aceite de oliva es una grasa saludable, por lo que reduce el riesgo de padecer enfermedades cardiovasculares, al igual que las nueces, que puedes consumirlas unas tres o cuatro veces por semana junto con otros frutos secos, siempre crudos, sin tostar ni sal.
Las legumbres, como las habas, lentejas, alubias o garbanzos son alimentos ricos en fibra soluble y calcio, que aportan carbohidratos y proteínas vegetales, además de vitaminas y minerales. Cabe citar entre las legumbres, la soja, que es rica en fitoestrógenos y ayuda a mantener los niveles de colesterol malo o LDL bajo y aumentar el colesterol bueno o HDL, por lo que puedes consumirla con regularidad También el tofu, derivado de la soja, resulta beneficioso para el aparato cardiovascular.
El aguacate aporta ácidos grasos insaturados y contribuye a disminuir el colesterol malo y aumentar el colesterol bueno, el aceite de oliva es una grasa saludable, por lo que reduce el riesgo de padecer enfermedades cardiovasculares, al igual que las nueces, que puedes consumirlas unas tres o cuatro veces por semana junto con otros frutos secos, siempre crudos, sin tostar ni sal.
Las legumbres, como las habas, lentejas, alubias o garbanzos son alimentos ricos en fibra soluble y calcio, que aportan carbohidratos y proteínas vegetales, además de vitaminas y minerales. Cabe citar entre las legumbres, la soja, que es rica en fitoestrógenos y ayuda a mantener los niveles de colesterol malo o LDL bajo y aumentar el colesterol bueno o HDL, por lo que puedes consumirla con regularidad También el tofu, derivado de la soja, resulta beneficioso para el aparato cardiovascular.
**FEC( Fundación Española del Corazón )
Prenatal exposure to common insecticide linked to decreases in cognitive functioning at age 7
Researchers from the Columbia Center for Children's Environmental Health at the Mailman School of Public Health report evidence of a link between prenatal exposure to the insecticide chlorpyrifos and deficits in IQ and working memory at age seven. This is the first study to evaluate the neurotoxicity of prenatal chlorpyrifos exposure on cognitive development at the time of school entry. Findings are online in Environmental Health Perspectives. Until banned for indoor residential use by the U.S. Environmental Protection Agency in 2001, chlorpyrifos, an organophosphate pesticide, was one of the most widely used insecticides for residential pest control. In a sample of 265 New York City minority children, born prior to the ban, the researchers found evidence that increases in the amount of chlorpyrifos in the babies' umbilical cord blood were associated with decreases in performance on a measure of cognitive functioning at age 7. Specifically, higher prenatal exposure was associated with lower scores on two different scales of the Wechsler Intelligence Scales for Children (WISC-IV). On average, for each standard deviation increase in chlorpyrifos exposure, the full-Scale IQ was reduced by 1.4% (0.94 to 1.8 points) and Working Memory was reduced by 2.8% (1.6 to 3.7 points). This means that those children who have exposures in the upper 25% of the exposure distribution will score, on average, 5.5% (or 5.3 points) lower on the test of Working memory, and 2.7% (or 2.7) points lower on Full-scale IQ, as compared to those children in the lowest quartile. Furthermore, the decline in test scores begins at the lowest exposures and continues downward with increasing exposure levels. This suggests no evidence of a threshold, below which exposures are completely safe.
The Columbia researchers had previously reported that, prior to the ban, chlorpyrifos was detected in 100% of personal and indoor air samples, and 70% of umbilical cord blood collected from babies. They also reported that the amount of chlorpyrifos in babies' blood was associated with neurodevelopmental problems at age three. The new findings suggest that the relationship between prenatal chlorpyrifos exposure and neurodevelopmental deficits among cohort children persists through age seven, with possible longer-term educational implications.
"These observed deficits in cognitive functioning at 7 years of age could have implications for school performance," noted Virginia Rauh, ScD, deputy director of the Columbia Center for Children's Environmental Health (CCCEH), and lead author of the study. "Working memory problems may interfere with reading comprehension, learning and academic achievement, even if general intelligence remains in the normal range."
The good news, reports Robin Whyatt, DrPH, senior author on the paper, is that since the EPA ban took effect, exposure to the organophosphate has measurably declined. CCCEH scientists have found a 3-fold decrease in chlorpyrifos levels in personal and indoor air samples in the cohort and a more than 5-fold decrease in blood levels.
"However, agricultural use of chlorpyrifos is still permitted in the U.S.," says Dr. Whyatt, professor of Clinical Environmental Health Sciences and deputy director of CCCEH. "It is vitally important that we continue to monitor the levels of exposure in potentially vulnerable populations, especially in pregnant women in agricultural communities, as their infants may continue to be at risk."
Also published in Environmental Health Perspectives today, two other NIEHS/EPA funded Children's Environmental Health Centers present independent investigations of organophosphate pesticides and neurodevelopment. Although findings cannot be directly compared, these studies also found early cognitive and behavioral effects associated with prenatal organophosphate exposure.
**Source: Columbia University's Mailman School of Public Health
The Columbia researchers had previously reported that, prior to the ban, chlorpyrifos was detected in 100% of personal and indoor air samples, and 70% of umbilical cord blood collected from babies. They also reported that the amount of chlorpyrifos in babies' blood was associated with neurodevelopmental problems at age three. The new findings suggest that the relationship between prenatal chlorpyrifos exposure and neurodevelopmental deficits among cohort children persists through age seven, with possible longer-term educational implications.
"These observed deficits in cognitive functioning at 7 years of age could have implications for school performance," noted Virginia Rauh, ScD, deputy director of the Columbia Center for Children's Environmental Health (CCCEH), and lead author of the study. "Working memory problems may interfere with reading comprehension, learning and academic achievement, even if general intelligence remains in the normal range."
The good news, reports Robin Whyatt, DrPH, senior author on the paper, is that since the EPA ban took effect, exposure to the organophosphate has measurably declined. CCCEH scientists have found a 3-fold decrease in chlorpyrifos levels in personal and indoor air samples in the cohort and a more than 5-fold decrease in blood levels.
"However, agricultural use of chlorpyrifos is still permitted in the U.S.," says Dr. Whyatt, professor of Clinical Environmental Health Sciences and deputy director of CCCEH. "It is vitally important that we continue to monitor the levels of exposure in potentially vulnerable populations, especially in pregnant women in agricultural communities, as their infants may continue to be at risk."
Also published in Environmental Health Perspectives today, two other NIEHS/EPA funded Children's Environmental Health Centers present independent investigations of organophosphate pesticides and neurodevelopment. Although findings cannot be directly compared, these studies also found early cognitive and behavioral effects associated with prenatal organophosphate exposure.
**Source: Columbia University's Mailman School of Public Health
The Long-Term Effects of In Utero Exposures — The DES Story
It has been 40 years since the Journal published a seminal article by Herbst et al. (1971;284:878-81) noting the association of in utero exposure to a synthetic nonsteroidal estrogen, diethylstilbestrol (DES), and the development of a rare clear-cell adenocarcinoma (CCA) of the vagina in young women 15 to 22 years later. The identification of an in utero exposure that caused alterations to the anatomical and histologic structure of the female genital tract, infertility, and malignant transformation has changed medical thinking about both the embryologic development of the genital tract and the mechanism of carcinogenesis.
DES was developed in 1938 and used widely, including as a supplement to cattle feed in the 1960s and in humans for symptom relief from estrogen-deficiency states, postpartum lactation suppression, and treatment of prostate and breast cancer. Despite some evidence to the contrary, a 1948 study suggested that DES taken in early pregnancy prevented miscarriage.1 Over the subsequent two decades, and despite mounting evidence of lack of efficacy, DES was commonly prescribed for that purpose. Ultimately, however, it was acknowledged to be ineffective in the prevention of miscarriage. The exact number of offspring exposed to DES in utero is unknown but is thought to be several million.
The Registry for Research on Hormonal Transplacental Carcinogenesis had collected information on 431 cases of vaginal CCA by 1994. A 2007 analysis of lifetime risks of CCA reported a total of 143 cases per 97,831 person-years among women exposed to DES in utero.2 Estimates of CCA incidence among DES-exposed women range from 1 in 1000 to 1 in 10,000. Unlike the previously rare CCA that was found in postmenopausal women, CCA in DES-exposed women occurred at a median age of 19 years (range, 15 to 29 years). The registries also identified another cohort of young women — accounting for 20% of the total registry population — who were given that diagnosis during the same era but had no known history of DES exposure. This finding has led to conjectures that some of the mothers of women with CCA might have been exposed to DES through dietary sources.
The mechanism of carcinogenesis has been linked to aberrant embryologic development of the Müllerian ducts after exposure to DES. Chemicals that affect human fetal development are now called endocrine-disrupting chemicals, and an understanding of the changes caused by DES, the prototypical endocrine disruptor, has led to the identification of genetic pathways that govern the development of the reproductive tract. At a crucial developmental window in utero, DES exposure disorganizes uterine muscle layers; prevents vaginal epithelial stratification and the resorption of vaginal glands, causing vaginal adenosis; and leads to loss of the uterotubal junction. The anomalies of the reproductive tract are thought to be attributable in part to estrogen's ability to alter stromal epithelial interactions. In the past decade, DES-induced alterations of the expression of the Hox and Wnt gene families, which are involved in the patterning of the reproductive tract, have been identified. The fact that the incidence of CCA peaked during the teen years suggests that the hormonal changes of menarche triggered malignant transformation in vaginal adenosis.
For the women who were exposed to DES in utero, it meant being subjected to the trauma of multiple pelvic examinations with colposcopy and repeated biopsies, as well as living with the fear of developing cancer. Small, T-shaped uteri and other uterotubal anomalies that made it impossible to accommodate a growing fetus caused many of these women to have miscarriages — which occurred at twice the rate found among their non–DES-exposed contemporaries. Some sons of women who were given DES have also been reported to have epididymal cysts, microphallus, cryptorchidism, or testicular hypoplasia. The enormous health care costs for this cohort and the disruptions of their lives cannot be fully measured; in some cases, these effects have been devastating.
The lessons learned from the DES story are powerful. Endocrine disruptors may cause alterations in the reproductive tract that have severe consequences and form the basis of disease in adults decades later. Endocrine disruptors may come not only from ingested medicines, but potentially also from the environment through food. It is very difficult to recognize a teratogenic consequence of a prenatal exposure when the malformation does not manifest until 20 years later.
There continue to be unanswered questions about the cohort of DES-exposed offspring. Will they encounter other unique health problems as they age? A slight increase in the rate of breast cancer among DES-exposed women over 40 years of age has been reported, but there has been no increase in other gynecologic cancers. Are the children of DES-exposed people at higher risk for genetic changes and disease? Epigenetic changes have been seen in studies in animals. However, a 2008 study of the third generation — the grandchildren of women who were given DES during pregnancy — did not uncover an increased risk of disease in humans.5
Ultimately, the DES story humbles us. It serves as a reminder that though the narrow lens of today might reassure us that an intervention is safe, it is only with the wisdom of time that the full consequences of our actions are revealed.
*Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
This article (10.1056/NEJMp1104409) was published on April 20, 2011, at NEJM.org.
*Source Information
Drs. Goodman and Schorge are associate professors, and Dr. Greene is a professor, of obstetrics, gynecology, and reproductive biology at Harvard Medical School and Massachusetts General Hospital — both in Boston; Dr. Greene is also an associate editor of the Journal.
DES was developed in 1938 and used widely, including as a supplement to cattle feed in the 1960s and in humans for symptom relief from estrogen-deficiency states, postpartum lactation suppression, and treatment of prostate and breast cancer. Despite some evidence to the contrary, a 1948 study suggested that DES taken in early pregnancy prevented miscarriage.1 Over the subsequent two decades, and despite mounting evidence of lack of efficacy, DES was commonly prescribed for that purpose. Ultimately, however, it was acknowledged to be ineffective in the prevention of miscarriage. The exact number of offspring exposed to DES in utero is unknown but is thought to be several million.
The Registry for Research on Hormonal Transplacental Carcinogenesis had collected information on 431 cases of vaginal CCA by 1994. A 2007 analysis of lifetime risks of CCA reported a total of 143 cases per 97,831 person-years among women exposed to DES in utero.2 Estimates of CCA incidence among DES-exposed women range from 1 in 1000 to 1 in 10,000. Unlike the previously rare CCA that was found in postmenopausal women, CCA in DES-exposed women occurred at a median age of 19 years (range, 15 to 29 years). The registries also identified another cohort of young women — accounting for 20% of the total registry population — who were given that diagnosis during the same era but had no known history of DES exposure. This finding has led to conjectures that some of the mothers of women with CCA might have been exposed to DES through dietary sources.
The mechanism of carcinogenesis has been linked to aberrant embryologic development of the Müllerian ducts after exposure to DES. Chemicals that affect human fetal development are now called endocrine-disrupting chemicals, and an understanding of the changes caused by DES, the prototypical endocrine disruptor, has led to the identification of genetic pathways that govern the development of the reproductive tract. At a crucial developmental window in utero, DES exposure disorganizes uterine muscle layers; prevents vaginal epithelial stratification and the resorption of vaginal glands, causing vaginal adenosis; and leads to loss of the uterotubal junction. The anomalies of the reproductive tract are thought to be attributable in part to estrogen's ability to alter stromal epithelial interactions. In the past decade, DES-induced alterations of the expression of the Hox and Wnt gene families, which are involved in the patterning of the reproductive tract, have been identified. The fact that the incidence of CCA peaked during the teen years suggests that the hormonal changes of menarche triggered malignant transformation in vaginal adenosis.
For the women who were exposed to DES in utero, it meant being subjected to the trauma of multiple pelvic examinations with colposcopy and repeated biopsies, as well as living with the fear of developing cancer. Small, T-shaped uteri and other uterotubal anomalies that made it impossible to accommodate a growing fetus caused many of these women to have miscarriages — which occurred at twice the rate found among their non–DES-exposed contemporaries. Some sons of women who were given DES have also been reported to have epididymal cysts, microphallus, cryptorchidism, or testicular hypoplasia. The enormous health care costs for this cohort and the disruptions of their lives cannot be fully measured; in some cases, these effects have been devastating.
The lessons learned from the DES story are powerful. Endocrine disruptors may cause alterations in the reproductive tract that have severe consequences and form the basis of disease in adults decades later. Endocrine disruptors may come not only from ingested medicines, but potentially also from the environment through food. It is very difficult to recognize a teratogenic consequence of a prenatal exposure when the malformation does not manifest until 20 years later.
There continue to be unanswered questions about the cohort of DES-exposed offspring. Will they encounter other unique health problems as they age? A slight increase in the rate of breast cancer among DES-exposed women over 40 years of age has been reported, but there has been no increase in other gynecologic cancers. Are the children of DES-exposed people at higher risk for genetic changes and disease? Epigenetic changes have been seen in studies in animals. However, a 2008 study of the third generation — the grandchildren of women who were given DES during pregnancy — did not uncover an increased risk of disease in humans.5
Ultimately, the DES story humbles us. It serves as a reminder that though the narrow lens of today might reassure us that an intervention is safe, it is only with the wisdom of time that the full consequences of our actions are revealed.
*Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
This article (10.1056/NEJMp1104409) was published on April 20, 2011, at NEJM.org.
*Source Information
Drs. Goodman and Schorge are associate professors, and Dr. Greene is a professor, of obstetrics, gynecology, and reproductive biology at Harvard Medical School and Massachusetts General Hospital — both in Boston; Dr. Greene is also an associate editor of the Journal.
Kids' 'screen time' linked to early markers for cardiovascular disease
Six-year-olds who spent the most time watching television, using a computer or playing video games had narrower arteries in the back of their eyes — a marker of future cardiovascular risk, in a first-of-its-kind study reported in Arteriosclerosis, Thrombosis and Vascular Biology: Journal of the American Heart Association. Australian researchers found that more sedentary behavior such as "screen time" was associated with an average narrowing of 2.3 microns in the retinal arteriolar caliber. A micron is one thousandth of a millimeter or one-25th of a thousandth of an inch.
In the study, 6- to 7-year-olds who regularly participated in outdoor physical activity had 2.2 microns wider average retinal arteriolar compared to those children with the lowest level of activity.
The magnitude of the narrowing associated with each hour of television/computer viewing was similar to that associated with 10 millimeters of mercury (mm HG) increase in systolic blood pressure in children, researchers said.
"We found that children with a high level of physical activity had a more beneficial microvascular profile compared to those with the lowest levels of physical activity," said Bamini Gopinath, Ph.D., lead author and senior research fellow at the Center for Vision Research at the University of Sydney. "This suggests that unhealthy lifestyle factors may influence microcirculation early in life and increase the risk of cardiovascular disease and hypertension later in life."
Retinal microvascular caliber is a marker for cardiovascular disease and high blood pressure in adults. But this is the first time that a sedentary lifestyle in childhood showed a narrowing of the vessels in the retina that could be a subclinical marker for cardiovascular disease in the future.
The study included 1,492 children in 34 primary schools in Sydney, Australia. Parents answered a 193-item questionnaire, providing the number of hours spent each week in indoor and outdoor physical activity and sedentary activity such as watching television, videogames, computer time and reading.
Researchers took digital photographs of the vasculature in the back of each child's eye, then calculated average retinal vascular calibers. Height, weight, body mass index (BMI) and three separate blood pressure measurements were taken and averaged.
On average, the children spent 1.9 hours per day in screen time and 36 minutes a day in total physical activity. Children in the highest levels of physical activity at just over an hour or more had significantly wider average retinal arteriolar caliber than those spending just under half an hour or less per day.
Increased screen time was associated with narrower average retinal arteriolar diameter after adjusting for age, sex, ethnicity, iris color, length of the eyeball, BMI, birth weight and blood pressure. Each hour per day of TV viewing time was associated on average with 1.53 microns narrower retinal arteriolar caliber.
"Excessive screen time leads to less physical activity, unhealthy dietary habits and weight gain," Gopinath said. "Replacing one hour a day of screen time with physical activity could be effective in buffering the effects of sedentariness on the retinal microvasculature in children. Free play should be promoted and schools should have a mandatory two hours a week in physical activity for children."
Physical activity enhances endothelial function and increases blood flow resulting in enhanced nitric oxide production, which has a positive effect on the linings of blood vessels.
The researchers said their findings might not be applicable to other regions of the world because of the temperate climate in Australia, where children are more apt to play outdoors. Study limitations included the use of parental rather than objective measurement of the children's time spent in physical and sedentary activities.
"Parents need to get their children up and moving and off the couch," Gopinath said. "Parents can also lead the way by being more physically active themselves."
**Source: American Heart Association
In the study, 6- to 7-year-olds who regularly participated in outdoor physical activity had 2.2 microns wider average retinal arteriolar compared to those children with the lowest level of activity.
The magnitude of the narrowing associated with each hour of television/computer viewing was similar to that associated with 10 millimeters of mercury (mm HG) increase in systolic blood pressure in children, researchers said.
"We found that children with a high level of physical activity had a more beneficial microvascular profile compared to those with the lowest levels of physical activity," said Bamini Gopinath, Ph.D., lead author and senior research fellow at the Center for Vision Research at the University of Sydney. "This suggests that unhealthy lifestyle factors may influence microcirculation early in life and increase the risk of cardiovascular disease and hypertension later in life."
Retinal microvascular caliber is a marker for cardiovascular disease and high blood pressure in adults. But this is the first time that a sedentary lifestyle in childhood showed a narrowing of the vessels in the retina that could be a subclinical marker for cardiovascular disease in the future.
The study included 1,492 children in 34 primary schools in Sydney, Australia. Parents answered a 193-item questionnaire, providing the number of hours spent each week in indoor and outdoor physical activity and sedentary activity such as watching television, videogames, computer time and reading.
Researchers took digital photographs of the vasculature in the back of each child's eye, then calculated average retinal vascular calibers. Height, weight, body mass index (BMI) and three separate blood pressure measurements were taken and averaged.
On average, the children spent 1.9 hours per day in screen time and 36 minutes a day in total physical activity. Children in the highest levels of physical activity at just over an hour or more had significantly wider average retinal arteriolar caliber than those spending just under half an hour or less per day.
Increased screen time was associated with narrower average retinal arteriolar diameter after adjusting for age, sex, ethnicity, iris color, length of the eyeball, BMI, birth weight and blood pressure. Each hour per day of TV viewing time was associated on average with 1.53 microns narrower retinal arteriolar caliber.
"Excessive screen time leads to less physical activity, unhealthy dietary habits and weight gain," Gopinath said. "Replacing one hour a day of screen time with physical activity could be effective in buffering the effects of sedentariness on the retinal microvasculature in children. Free play should be promoted and schools should have a mandatory two hours a week in physical activity for children."
Physical activity enhances endothelial function and increases blood flow resulting in enhanced nitric oxide production, which has a positive effect on the linings of blood vessels.
The researchers said their findings might not be applicable to other regions of the world because of the temperate climate in Australia, where children are more apt to play outdoors. Study limitations included the use of parental rather than objective measurement of the children's time spent in physical and sedentary activities.
"Parents need to get their children up and moving and off the couch," Gopinath said. "Parents can also lead the way by being more physically active themselves."
**Source: American Heart Association
Hacia un control de la malaria con mosquitos transgénicos
La difícil lucha contra la malaria, enfermedad que afecta a más de 300 millones de personas cada año y que mata a unas 800.000 -niños más de la mitad-, se aborda desde varios frentes, a la espera de futuras vacunas efectivas. De momento, las posibilidades se reducen al uso de medicamentos profilácticos costosos y con efectos secundarios no despreciables y a la fumigación con potentes insecticidas para eliminar los mosquitos anopheles, que son pieza clave de la transmisión de la enfermedad. Pero el uso de insecticidas tiene efectos negativos en la salud humana y un gran impacto ambiental porque el exterminio no diferencia las especies de insectos nocivos de los que no lo son. La desecación de humedales y marismas, donde viven los mosquitos, es efectiva pero tampoco está exenta de efectos medioambientales indeseables. Ahora unos científicos británicos y estadounidenses presentan los resultados satisfactorios de unos experimentos que abren la puerta a otra estrategia de lucha: la difusión de insectos inhabilitados, por ingeniería genética, para transmitir la enfermedad. Sería una forma de guerra biológica, pero controlada, sin afectar a especies ajenas a la malaria.
Ya se habían logrado mosquitos transgénicos con una capacidad muy limitada de transmisión de la enfermedad. El problema era que la modificación del ADN desaparecía rápidamente en la población de insectos al no conferir ninguna ventaja a los transgénicos frente a los naturales. Andrea Crisanti (Imperial College, Londres) y sus colegas explican en la revista Nature cómo han hecho sus experimentos y el éxito que supone lograr que una modificación genética realizada en unos mosquitos se propague en una población y que se conserve tras varias generaciones.
Para empezar hicieron, en el laboratorio, una población de mosquitos con un gen que produce un marcador verde fluorescente para facilitar la identificación de los insectos en el experimento. A continuación permitieron que se mezclaran con esta población inicial unos cuantos mosquitos con otro cambio en su ADN, esta vez el importante para el experimento, cuyo efecto es inactivar permanentemente el gen de la fluorescencia verde. A la hora del recuento comprobaron que, si en la población inicial más del 99% mostraban la coloración del marcador, tras doce generaciones, ese porcentaje se había reducido a menos de la mitad, es decir que la modificación capaz de anular el gen de la fluorescencia se estaba extendiendo. El éxito del experimento indica que es posible utilizar esta técnica para propagar en poblaciones salvajes de mosquitos una modificación genética específica, por ejemplo que limite su capacidad transmisora de la malaria.
Crisanti y sus colegas, explica el Imperial College, han basado sus ensayos en Anopheles gambiae, uno de los principales mosquitos implicados en la propagación de la enfermedad, y lo que han hecho es introducir en ellos una secuencia de ADN que no sólo inactiva el gen de la fluorescencia verde sino que al mismo tiempo inserta una copia de si mismo en su lugar. Y esto ocurre en las células espermáticas del mosquito, de manera que cuando se cruza, casi todos sus descendientes reciben ese fragmento específico de ADN, que poco a poco se va difundiendo por la población en sucesivas generaciones.
"La malaria es una enfermedad terrible. Hay unas 3.500 especies de mosquitos en el mundo y solo unas pocas transmiten el mortal parásito Plasmodium falciparum", explica uno de los científicos autores del nuevo trabajo, Austin Burt. "Esta tecnología nos permite enfocar nuestro trabajo exclusivamente en el control de esas especies de mosquitos peligrosas". El primer firmante del artículo en Nature, Nikolai Windbichler, explica que en esta nueva estrategia, la modificación genética se hereda directamente a los descendientes en la reproducción, "lo que la convierte en una medida de control biológico específico que no afecta siquiera a otras especies de mosquitos".
Este equipo científico (con participación de expertos de la Universidad de Washington en Seattle, EEUU) está ya trabajando en el siguiente paso, centrándose en genes que el mosquito necesita para su reproducción o para la transmisión de la malaria. Si los experimentos tienen éxito, con esta tecnología se podría soltar en la naturaleza -en zonas donde la enfermedad es endémica- una cantidad reducida de mosquitos transgénicos que propagarían sus genes y se reduciría notablemente el número de mosquitos transmisores. Sería una forma barata, segura y altamente efectiva para luchar contra la malaria, afirman Crisanti y sus colegas, que cuentan con poner a punto la tecnología en cinco o seis años.
Para empezar hicieron, en el laboratorio, una población de mosquitos con un gen que produce un marcador verde fluorescente para facilitar la identificación de los insectos en el experimento. A continuación permitieron que se mezclaran con esta población inicial unos cuantos mosquitos con otro cambio en su ADN, esta vez el importante para el experimento, cuyo efecto es inactivar permanentemente el gen de la fluorescencia verde. A la hora del recuento comprobaron que, si en la población inicial más del 99% mostraban la coloración del marcador, tras doce generaciones, ese porcentaje se había reducido a menos de la mitad, es decir que la modificación capaz de anular el gen de la fluorescencia se estaba extendiendo. El éxito del experimento indica que es posible utilizar esta técnica para propagar en poblaciones salvajes de mosquitos una modificación genética específica, por ejemplo que limite su capacidad transmisora de la malaria.
Crisanti y sus colegas, explica el Imperial College, han basado sus ensayos en Anopheles gambiae, uno de los principales mosquitos implicados en la propagación de la enfermedad, y lo que han hecho es introducir en ellos una secuencia de ADN que no sólo inactiva el gen de la fluorescencia verde sino que al mismo tiempo inserta una copia de si mismo en su lugar. Y esto ocurre en las células espermáticas del mosquito, de manera que cuando se cruza, casi todos sus descendientes reciben ese fragmento específico de ADN, que poco a poco se va difundiendo por la población en sucesivas generaciones.
"La malaria es una enfermedad terrible. Hay unas 3.500 especies de mosquitos en el mundo y solo unas pocas transmiten el mortal parásito Plasmodium falciparum", explica uno de los científicos autores del nuevo trabajo, Austin Burt. "Esta tecnología nos permite enfocar nuestro trabajo exclusivamente en el control de esas especies de mosquitos peligrosas". El primer firmante del artículo en Nature, Nikolai Windbichler, explica que en esta nueva estrategia, la modificación genética se hereda directamente a los descendientes en la reproducción, "lo que la convierte en una medida de control biológico específico que no afecta siquiera a otras especies de mosquitos".
Este equipo científico (con participación de expertos de la Universidad de Washington en Seattle, EEUU) está ya trabajando en el siguiente paso, centrándose en genes que el mosquito necesita para su reproducción o para la transmisión de la malaria. Si los experimentos tienen éxito, con esta tecnología se podría soltar en la naturaleza -en zonas donde la enfermedad es endémica- una cantidad reducida de mosquitos transgénicos que propagarían sus genes y se reduciría notablemente el número de mosquitos transmisores. Sería una forma barata, segura y altamente efectiva para luchar contra la malaria, afirman Crisanti y sus colegas, que cuentan con poner a punto la tecnología en cinco o seis años.
**Publicado en "EL PAIS"
Un hallazgo abre paso al trasplante de flora intestinal entre humanos
La flora intestinal (las bacterias que habitan el tracto digestivo) no es tan específica de cada individuo como se creía. Igual que hay grupos sanguíneos, en los seres humanos hay tres grupos de flora intestinal: A, B y C. En un futuro, este descubrimiento podría modificar el abordaje de enfermedades como la Crohn, la colitis ulcerosa, la diabetes o la obesidad. Otra de las posibilidades es el trasplante de flora intestinal. Como si de un bosque a repoblar se tratara, el trasplante permitiría reintroducir las especies ausentes. Saber que todo individuo corresponde a uno de estos grupos permitirá definir mejor el tipo de trasplante que cada uno necesita.
"Deberemos trasplantar las bacterias adecuadas, si no sería como, por ejemplo, intentar llevar una ardilla que vive en un bosque escandinavo a la selva, en dos días moriría", explica Francisco Guarner, responsable del proyecto MetaHIT en España e investigador Instituto de Investigación Vall d'Hebrón (VHIR). El trabajo se publica hoy en Nature. "Tal vez debamos empezar a pensar en el enterotipo de flora intestinal como si se tratara de un grupo sanguíneo, especialmente cuando se aborden determinados tratamientos", añade.
-Países desarrollados
Esta estructura esencial determina el funcionamiento del intestino del individuo y se definiría durante el primer y el segundo año de vida del bebé, explica Guarner. "Hasta ahora creíamos que la flora intestinal de cada individuo estaba determinada por la procedencia (y el entorno) y que era como una firma digital individual, no pensábamos que hubiese estos tres grupos comunes", reconoce. Los investigadores han analizado el microbioma de la flora intestinal de pacientes de España, Dinamarca, Francia, Italia, Japón y Estados Unidos, por lo que el investigador cree que ahora queda por ver si en estos grupos también encajarían las personas que viven en países menos desarrollados.
En las anteriores fases del proyecto, los investigadores averiguaron que el intestino humano está poblado por unos 10 millones de bacterias. Pertenecen a más de 1.000 especies diferentes, y la presencia o ausencia de algunas de ellas se correlaciona con enfermedades intestinales. Con los nuevos datos han visto que en cada uno de los enterotipos identificados predomina un tipo de bacteria diferente.
**Publicado en "EL PAIS"
"Deberemos trasplantar las bacterias adecuadas, si no sería como, por ejemplo, intentar llevar una ardilla que vive en un bosque escandinavo a la selva, en dos días moriría", explica Francisco Guarner, responsable del proyecto MetaHIT en España e investigador Instituto de Investigación Vall d'Hebrón (VHIR). El trabajo se publica hoy en Nature. "Tal vez debamos empezar a pensar en el enterotipo de flora intestinal como si se tratara de un grupo sanguíneo, especialmente cuando se aborden determinados tratamientos", añade.
-Países desarrollados
Esta estructura esencial determina el funcionamiento del intestino del individuo y se definiría durante el primer y el segundo año de vida del bebé, explica Guarner. "Hasta ahora creíamos que la flora intestinal de cada individuo estaba determinada por la procedencia (y el entorno) y que era como una firma digital individual, no pensábamos que hubiese estos tres grupos comunes", reconoce. Los investigadores han analizado el microbioma de la flora intestinal de pacientes de España, Dinamarca, Francia, Italia, Japón y Estados Unidos, por lo que el investigador cree que ahora queda por ver si en estos grupos también encajarían las personas que viven en países menos desarrollados.
En las anteriores fases del proyecto, los investigadores averiguaron que el intestino humano está poblado por unos 10 millones de bacterias. Pertenecen a más de 1.000 especies diferentes, y la presencia o ausencia de algunas de ellas se correlaciona con enfermedades intestinales. Con los nuevos datos han visto que en cada uno de los enterotipos identificados predomina un tipo de bacteria diferente.
**Publicado en "EL PAIS"
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