Gracias a los participantes del programa en internet Foldit, unos investigadores han logrado resolver la configuración de una enzima de un retrovirus

Los jugadores en internet del programa Foldit han logrado solucionar un problema de la biología que traía de cabeza a los científicos desde hace más de diez años: resolver la estructura tridimensional de una encima concreta de un retrovirus similar al VIH. Y los voluntarios lo han logrado en tres semanas. "Queríamos ver si la intuición humana puede tener éxito donde los métodos automáticos han fallado", explica Firas Khatib, bioquímico de la Universidad de Washington (EE UU)
Los científicos, dirigidos por David Baker, querían determinar la estructura exacta, tridimensional, de una enzima, del tipo de las proteasas retrovirales que tienen un papel clave en la maduración y proliferación de los retrovirus, lo que abriría la perspectiva de identificar nuevas dianas para fármacos.
La descripción -y el diseño- tridimensional de moléculas de interés biológico es una tarea difícil, que suele exigir el uso de potentes ordenadores para representar cómo los componentes de las mismas se van plegando. En el caso de la enzima del retrovirus, Baker y sus colegas pensaron que seria una buena idea recurrir a ese Foldit, desarrollado por investigadores de la misma Universidad de Washington.
Los jugadores, ante el reto, parten de las cadenas de aminoácidos conocidos de la enzima y van rotándolas y plegándolas, sólo limitados por las reglas de la física y la química, y atendiendo a los requerimientos energéticos del sistema. Es como un rompecabezas en 3D en el que se van resolviendo estrategias de configuración. Foldit no pretende solo utilizar la capacidad de cálculo de ordenadores privados, como otros programas de colaboración con la ciencia, sino implicar también al usuario, su capacidad, su intuición y su suerte. Sobre los modelos generados por los jugadores, los científicos trabajan para irlos refinando hasta obtener esa configuración tridimensional buscada.
Foldit surgió en 2008 con la idea de "utilizar la capacidad de razonamiento espacial de las personas, algo en lo que no son muy buenos los ordenadores", explica Seth Cooper, investigador la Computación de la Universidad de Washington. "Los juegos proporcionan el marco para aunar las capacidades de los ordenadores y de los humanos".
La configuración tridimensional definitiva de la enzima se ha presentado en la revista \Nature Structural &Molecular Biology\ y los jugadores de Foldit que dieron con la mejor solución son coautores del artículo correspondiente, junto con los científicos.
"La ingenuidad de las personas que usan estos juegos es una fuerza formidable que, si se dirige debidamente, puede ser utilizada para resolver muchos problemas científicos", dice Khatib en un comunicado de la Universidad de Washington.

**Publicado en "EL PAIS"

Living alone is associated with an increased risk of alcohol-related deaths

Living alone is associated with an increased risk of alcohol-related mortality -- from alcohol-related diseases and accidents -- according to a Finnish study published in PLoS Medicine, suggesting that a lack of social relationships should be regarded as a potential risk factor for death from alcohol related causes. However, the idea that a lack of social relationships is a risk factor for death is still not widely recognised by health professionals, policy makers, or the public. Researchers led by Kimmo Herttua from the Finnish Institute of Occupational Health, in Helsinki, found a greater increase in alcohol-related deaths (particularly fatal liver disease) among people living alone compared to married and cohabiting people after an alcohol price reduction in 2004, suggesting that people living alone are more vulnerable to the adverse effects of increased alcohol availability.
The authors analyzed information on about 80% of all people who died in Finland between 2000 and 2007 and found that roughly 18,200 people--two-thirds of whom lived alone--died from underlying alcohol-related causes such as liver disease and alcoholic poisoning or contributory alcohol-related factors such as accidents, violence and cardiovascular disease.
Furthermore, for people living alone (particularly those aged 50-69 years) a reduction in the price of alcohol in 2004 was associated with a substantial increase in the alcohol-related mortality rate. For example, between 2000 and 2003, men living alone were 3.7 times as likely to die of liver disease as married or cohabiting men but between 2004 and 2007, they were 4.9 times as likely to die of liver disease. The pattern of mortality was similar but lower in women living alone.
The authors conclude: "Living alone is associated with a substantially increased risk of alcohol-related mortality, irrespective of gender, socioeconomic status, or the specific cause of death."
They add: "Further longitudinal research is needed to confirm the generalizability of our findings to other countries with different alcohol cultures (e.g., Mediterranean wine culture) and to identify selective and causal processes underlying the association between living alone and alcohol abuse."

*Source: Public Library of Science

Association found between stress and breast cancer aggressiveness

Psychosocial stress could play a role in the etiology of breast cancer aggressiveness, particularly among minority populations, according to study results presented at the Fourth AACR Conference on The Science of Cancer Health Disparities, held here from Sept. 18-21, 2011. "We found that after diagnosis, black and Hispanic breast cancer patients reported higher levels of stress than whites, and that stress was associated with tumor aggressiveness," said Garth H. Rauscher, Ph.D., associate professor of epidemiology in the division of epidemiology and biostatistics at the School of Public Health, University of Illinois at Chicago.
Rauscher and colleagues studied patient-reported perceptions of fear, anxiety and isolation, together referred to as psychosocial stress, and associations with breast cancer aggressiveness. He cautioned that patients' stress levels were examined two to three months post-diagnosis.
The study included 989 breast cancer patients who were recently diagnosed; of those, 411 were non-Hispanic black, 397 were non-Hispanic white, and 181 were Hispanic. Results showed that psychosocial stress scores were higher for both black and Hispanic patients compared to white patients.
"Those who reported higher levels of stress tended to have more aggressive tumors. However, what we don't know is if we had asked them the same question a year or five years before diagnosis, would we have seen the same association between stress and breast cancer aggressiveness?
"It's not clear what's driving this association. It may be that the level of stress in these patients' lives influenced tumor aggressiveness. It may be that being diagnosed with a more aggressive tumor, with a more worrisome diagnosis and more stressful treatments, influenced reports of stress. It may be that both of these are playing a role in the association. We don't know the answer to that question," Rauscher said.

**Source: American Association for Cancer Research

En los seis primeros meses de vida, la lactancia materna es suficiente

La Organización Mundial de la Salud (OMS) recomienda que los niños se alimenten exclusivamente de leche materna durante sus seis primeros meses de vida. Sin embargo, por temor a que la lactancia sea insuficiente para garantizar las necesidades del pequeño, muchas madres introducen una dieta complementaria antes de que se cumpla este periodo.
Un estudio acaba de demostrar que esta práctica está injustificada y que dar solamente el pecho proporciona la energía adecuada para un desarrollo correcto.
"Cuando la madre recibe apoyo y sigue las recomendaciones de la OMS, las tomas de leche son altas, hay una adecuada ingesta de calorías y un crecimiento normal", comentan los autores de este trabajo, de la Universidad de Glasgow (Reino Unido), en el último número de la revista 'Pediatrics'.

-Seguimiento
Para llevar a cabo su investigación, estos autores realizaron un seguimiento a un grupo de 50 madres que participaban en diferentes grupos de lactancia en Escocia. Entre otras pruebas, evaluaron cuántas de ellas mantenían la lactancia exclusiva después de 15 y 25 semanas y cuál era la cantidad y la calidad de la leche que estaban tomando sus pequeños -a través de un método para el cálculo de consumo de energía-. Además, también pesaron y midieron periódicamente a los niños para comprobar su desarrollo.
Un total de 47 madres completaron la investigación. De ellas, 41 seguían alimentando exclusivamente con lactancia materna a sus hijos a los seis meses, mientras que el resto habían decidido completar su dieta con otros alimentos, principalmente papillas.
Al cruzar los datos obtenidos, los investigadores comprobaron que no había ninguna evidencia de que los niños que sólo tomaron leche durante sus seis primeros meses de vida tuvieran algún tipo de carencia nutricional. Tanto la cantidad de calorías que ingerían como su crecimiento estaban dentro de los patrones adecuados a su edad, subrayan los investigadores en el trabajo.
El estudio también puso de manifiesto que las madres que amamantaron a sus hijos durante este periodo no tuvieron que cambiar sus hábitos para mantener una adecuada alimentación de los bebés. "Nuestros datos muestran que no se produjeron mayores demandas de lactancia, expresadas en una mayor cantidad de tomas o un mayor tiempo empleado en la lactancia", comentan estos investigadores, quienes subrayan que sus datos echan por tierra el extendido mito de que la leche materna no es suficiente para alimentar a un niño de varios meses.

-Si el pecho fuera transparente…
"El único problema que tiene el pecho es que no es transparente y no permite ver cuánto está comiendo el bebé, lo que produce temor en muchas madres", señala a ELMUNDO.es Esperanza Martín, enfermera y coordinadora del comité de lactancia del Hospital La Paz de Madrid.
Sin embargo, según explica esta especialista, el miedo de las madres no es la única barrera con la que se encuentra la lactancia. A veces, el escaso apoyo familiar, la falta de coordinación entre los profesionales sanitarios o las dificultades para conciliar vida laboral y familiar también contribuyen al abandono prematuro de este tipo de alimentación.
En el año 2000, La Paz inició un estudio para comprobar la duración de la lactancia y las causas del abandono de la misma en un grupo de 78 mujeres que habían dado a luz en el centro a través de cesárea. Un 95% de ellas comenzaron a dar el pecho a sus hijos tras su nacimiento. A los 115 días del parto, un 74% continuaban con el hábito de forma exclusiva y unos meses después, sólo un 25% lo mantenía.
"En un 20% de los casos las mujeres habían iniciado otra alimentación porque el pediatra se lo había aconsejado al no tener en cuenta que las curvas de peso en los niños que se alimentan con leche materna y con leche de fórmula son distintas". Otras veces, la recomendación de abandono venía por parte de otros profesionales médicos –debido, por ejemplo, al inicio de determinados tratamientos médicos - e, incluso, por parte de la propia familia de la madre.
"A partir de esos datos, iniciamos un programa de apoyo a la lactancia que, entre otros factores, reforzó la coordinación con otros profesionales sanitarios, que no siempre tienen en mente la importancia de la lactancia, y aportó pautas a las madres para saber cómo solucionar eventuales problemas", subraya Martín.
En 2006 comprobaron que el esfuerzo estaba dando sus frutos. Un estudio similar demostró que, a los 115 días de haber dado a luz, hasta un 96% de las nuevas madres continuaban dando el pecho a sus pequeños.
"La leche materna es el mejor alimento que puede tener un bebé para su adecuado desarrollo y es importante apoyar a las madres para que puedan amamantar a sus hijos", concluye.

**Publicado en "EL MUNDO"

Genetic factors behind high blood pressure

High blood pressure is a well-known risk factor for heart disease. Researchers at the Sahlgrenska Academy at the University of Gothenburg, Sweden, have participated in an international study of 200,000 Europeans which has identified 16 new genetic variations that affect blood pressure. The discovery, published in Nature, is an important step towards better diagnostics and treatment. A billion people worldwide suffer from high blood pressure and are therefore in the danger zone for the likes of heart disease and stroke. Effective prediction and control of high blood pressure is therefore one of the most pressing global health issues.

-Analyzing genetic data
Researchers from the Sahlgrenska Academy at the University of Gothenburg are among an international consortium of more than 400 researchers from the US, Europe, Asia and Australia hoping to identify which parts of our genes influence blood pressure by sifting through vast quantities of genetic data.

-2.5 million DNA variations
In their latest study, the researchers analysed more than 2.5 million DNA variations from more than 200,000 Europeans. The results, published in the journal Nature, reveal 16 previously unknown genetic regions with interesting genes that regulate the body's blood pressure -- both the lower level when the heart expands (diastolic) and the upper level when the heart contracts (systolic).

-Genetic risk groups
With the help of these newly discovered genetic variations, the researchers have constructed genetic risk groups to help predict the risk of strokes and heart attacks. "We've been able to classify individuals on the basis of how many risk variants for hypertension they have in their genes" says Fredrik Nyberg, a researcher from the Sahlgrenska Academy working on the project.

-Important step forward
In another study published at the same time in Nature Genetics, the researchers from Gothenburg identify additional new genetic regions and genes controlling two other measures of blood pressure: pulse pressure (the difference between systolic and diastolic) and mean arterial pressure (an average of systolic and diastolic). The study shows how important it is to analyse different measures of blood pressure. For example, pulse pressure is a marker of rigidity in the arteries carrying blood from the heart to the body, and different genes seem to control different aspects of blood pressure.
The results of the two studies are considered to be an important step towards understanding how the body regulates blood pressure, and the newly discovered genetic regions are potential targets for future treatments.

**Source: University of Gothenburg

African-American men living in poor sunlight areas at risk for vitamin D deficiency

African-American men living in low sunlight areas are more likely to experience vitamin D deficiency than European-American men living in the same environment. Researchers believe that these findings should change recommendations for daily intake of vitamin D. "This study shows that across the board vitamin D recommendations just won't work for everybody," said Adam B. Murphy, M.D., M.B.A., clinical instructor in the department of urology at Northwestern University Feinberg School of Medicine, who reported the study at the Fourth AACR Conference on The Science of Cancer Health Disparities, held Sept. 18-21, 2011, in Washington, D.C.
"With so many diseases linked to low levels of vitamin D, we should have more stratified recommendations to consider groups within the population instead of making monolithic suggestions," he added.
Researchers evaluated the marker for vitamin D -- the 25 hydroxyvitamin D level (25-OH D level) -- in 492 men aged 40 to 79 years who lived in Chicago, a low ultraviolet radiation (UVR) part of the country. Of that group, 93 percent of African-American men and 69.7 percent of European-American men were vitamin D deficient; having 25-OH D levels of less than 30 ng/mL.
Results showed that vitamin D levels were low in African American men, those with lower income and those with higher body mass index. Low sunlight exposure is a known factor in lower levels of vitamin D, but researchers found that African American men still had lower levels of vitamin D in sunnier seasons.
Murphy attributes low vitamin D levels to the composition of African-American skin, which contains more of the pigment melanin than lighter skin. When UVR light hits the skin cells, it reacts with the molecule 7-dehydrocholesterol to begin the production of vitamin D, which is then further processed by the body to make active vitamin D. In African-Americans, though, melanin blocks UVR rays from being absorbed, thus reducing the amount of vitamin D naturally produced.
Vitamin D deficiency has been linked to multiple diseases, including breast cancer, prostate cancer, diabetes, rheumatoid arthritis and multiple sclerosis, which is why Murphy believes it is essential to adjust recommendations to reflect differences between African Americans and European-Americans.
"Because we have a lot of special populations in the United States -- people who have darker skin, people who cover their skin for religious reasons and people who live in poor sunlight environments -- there shouldn't be uniform vitamin D recommendations for the entire population," he said.

**Source: American Association for Cancer Research

Preterm birth associated with higher risk of death in early childhood, young adulthood

In a study that included more than 600,000 individuals born in Sweden between 1973-1979, those born preterm (less than 37 weeks gestation) had a higher risk of death during early childhood and young adulthood than persons born at term, according to a study in the September 21 issue of JAMA. Preterm birth is the leading cause of perinatal (pertaining to the period immediately before and after birth) illness and death in developed countries. "Although the early effects of preterm birth are well documented, less is known about the longer-term outcomes in adulthood. These outcomes have a growing clinical and public health importance because of the high prevalence of preterm birth and improved early survival," the authors write. In the past 3 decades, the prevalence of preterm birth in the United States has increased to more than 12 percent. "As a result, large numbers of individuals who were born preterm are now surviving to adulthood. A comprehensive understanding of their outcomes in adulthood is needed to enable earlier prevention, detection, and treatment of the long-term health sequelae."
Casey Crump, M.D., Ph.D., of Stanford University, Stanford, Calif., and colleagues conducted a study to examine the association between gestational age at birth and mortality in young adulthood. The study included a national cohort of 674,820 individuals born in Sweden in 1973 through 1979 who survived to age 1 year, including 27,979 (4.1 percent) born preterm, followed up to 2008. A total of 7,095 deaths occurred in follow-up from age 1 year to the maximum attained ages of 29 to 36 years.
The researchers found a strong inverse association between gestational age at birth and mortality in early childhood (ages 1-5 years), no association was observed in late childhood (ages 6-12 years) or adolescence (ages 13-17 years), and an inverse association reappeared in young adulthood (ages 18-36 years). In early childhood as well as young adulthood, preterm birth was associated with increased mortality even among individuals born late preterm (34-36 weeks), relative to those born full-term.
"In young adulthood, gestational age at birth had the strongest inverse association with mortality from congenital anomalies and respiratory, endocrine, and cardiovascular disorders and was not associated with mortality from neurological disorders, cancer, or injury," the authors write.
The researchers write that, to their knowledge, this is the first study to report the specific contribution of gestational age at birth on mortality in adulthood. "The underlying mechanisms are still largely unknown but may involve a complex interplay of fetal and postnatal nutritional abnormalities; other intrauterine exposures, including glucocorticoid [a steroid hormone] and sex hormone alterations; and common genetic factors."
"Although most survivors have a high level of function and self-reported quality of life in young adulthood, our previous and current findings demonstrate the increased long-term morbidities and mortality that may also be expected. Clinicians will increasingly encounter the health sequelae of preterm birth throughout the life course and will need to be aware of the long-term effects on the survivors, their families, and society."

**Source: JAMA and Archives Journals