During a decade of receiving mammograms, more than half of cancer-free women will be among those summoned back for more testing because of false-positive results, and about one in 12 will be referred for a biopsy. Simply shifting screening to every other year lowers a woman's probability of having one of these false-positive episodes by about a third -- from 61 percent to 42 percent -- over the course of a decade.
A new study delving into false-positives in mammography looked at nearly 170,000 women between the ages of 40 and 59 from seven regions around the United States, and almost 4,500 women with invasive breast cancer. Because of the added decade of testing alone, it found, women who start mammograms at 40 instead of 50 are more likely to have false-positive results that lead to more testing.
"This study provides accurate estimates of the risk of a false-positive mammography and breast biopsy for women undergoing repeat mammography in community practice, and so provides important information about the potential harms of undergoing regular mammography," said co-author Karla Kerlikowske, a professor of medicine at the UCSF School of Medicine.
The study will be published in Annals of Internal Medicine. The research was led by Group Health Research Institute of Seattle for the Breast Cancer Surveillance Consortium.
"Recalls'' for a second mammogram for what turn out to be non-cancer results, known as false positives, may cause inconvenience and anxiety. Recommendations for fine-needle aspiration or surgical biopsy are less common, but can lead to unnecessary pain and scarring. The additional testing also contributes to rising medical costs.
Kerlikowske is the lead author of an additional report -- to be published in the same issue of Annals -- that for the first time in the United States examines the accuracy of film mammography against digital, which has increasingly replaced older film screening.
That study looked at nearly 330,000 women between the ages of 40 and 79. The data was pooled from the Breast Cancer Surveillance Consortium, a collaborative network of mammography registries in the United States.
The researchers found that overall cancer detection rates were similar for both methods. However, digital screening may be better for women between the ages of 40 and 49 who are more likely to have extremely dense breasts associated with lower cancer detection. The study also found new evidence that digital mammography is better at detecting estrogen receptor-negative tumors, particularly in women aged 40 to 49 years.
Breast cancer may not be detected, the researchers caution, if a radiologist fails to identify a visible breast lesion or if a tumor is obscured by normal breast tissue. Additionally, an imperceptible tumor may grow quickly and be discovered through a clinical exam prior to the next mammogram.
Digital mammography was developed in part to improve the detection of breast cancer in dense breasts by improving the ability to distinguish normal dense breast tissue from isodense invasive cancer.
The authors note that for every 10,000 women 40 to 49 who are given digital mammograms, two more cases of cancer will be identified for every 170 additional false-positive examinations.
Healthy women will undergo 12 screening mammograms in their lifetimes if they follow U.S. Preventive Services Task Force guidelines that recommend biennial screening starting at age 50 and continuing until age 74. This is controversial, with many practitioners recommending annual mammograms.
If women start biennial screening at 40, they will undergo 17 exams; those who start annual screenings at age 40 will undergo 34 exams.
For the false-positive study, the researchers found that after a decade of annual screening, a majority of women will receive at least one false-positive result, and 7 to 9 percent will receive a false-positive biopsy recommendation.
"We conducted this study to help women know what to expect when they get regular screening mammograms over the course of many years,'' said study leader Rebecca Hubbard, PhD, an assistant investigator at Group Health Research Institute. "We hope that if women know what to expect with screening, they'll feel less anxiety if -- or when -- they are called back for more testing. In the vast majority of cases, this does not mean they have cancer.''
The researchers say that screening every other year would likely lessen the probability of false-positive results "but could also delay cancer diagnosis.'' However, for those diagnosed with cancer, the authors found women screened every two years were not significantly more likely to be diagnosed with late-stage cancer compared to those screened at one-year intervals.
The study stresses the importance of radiologists being able to review a patient's previous mammograms because it "may halve the odds of a false-positive recall.''
Co-authors of both studies are Diana L. Miglioretti, PhD, of Group Health Research Institute, and Bonnie C. Yankaskas, PhD, of the University of North Carolina at Chapel Hill.
The National Cancer Institute funded the studies.
**Source: University of California - San Francisco
18 October 2011
Muchos expertos se reafirman en que la obesidad es un problema sociofamiliar
Cualquier persona tiene mucho más riesgo de ser obeso si tiene un amigo, una esposa o un padre con sobrepeso. La obesidad es contagiosa, lo han demostrado varios estudios científicos en los últimos años. Pero, al parecer, también se 'transmiten' los efectos positivos de la cirugía de la obesidad.
John Morton, de la Universidad de Stanford, en California (EEUU), acaba de constatar en un estudio que los familiares de los pacientes que se someten a un 'by pass' gástrico (técnica quirúrgica que permite la restricción de la ingesta de alimentos y la disminución de su absorción) también pierden peso y, además, adoptan estilos de vida saludables. Aunque éste es uno de los dos trabajos científicos existentes en la actualidad que respaldan los efectos de la cirugía bariátrica en la familia, los cirujanos que la practican desde hace tiempo llevan años observándolos.
Es el caso Juan Carlos Ruiz de Adana, del Área de Cirugía General y Digestivo y coordinador de la Unidad de Obesidad Mórbida del Hospital de Getafe en Madrid. "Recuerdo perfectamente el caso de una madre que intervenimos en la unidad cuyos hijos también padecían obesidad. Efectivamente, los cambios de vida que ella adoptó tras la intervención sirvieron para que los familiares empezaran a llevar una dieta más sana y, consecuentemente, también redujeron peso. El estudio estadounidense reafirma el hecho de que la obesidad es un problema sociofamiliar. De ahí la importancia de tratar a todos los miembros en su conjunto. Nosotros hacemos terapias de grupo con este fin cuando decimos que un paciente va a ser intervenido", aclara.
Publicado en el último 'Archives of Surgery', el estudio ha sido llevado a cabo con 35 pacientes y 35 familiares, además de 15 de los hijos, menores de 18 años. Antes de la intervención, el 60% de los familiares adultos y hasta el 73% de los niños eran obesos.
Tanto pacientes como familiares (tenían que vivir en el mismo domicilio) recibieron tres sesiones educativas antes de la intervención y, posteriormente, tras la cirugía, acudieron a varias sesiones donde repasaron los estilos de vida adoptados a lo largo del año de seguimiento que duró la investigación.
"En cada visita clínica, se proporcionó tanto a los pacientes como a los familiares la dieta estándar y el asesoramiento sobre el estilo de vida que acompaña a la cirugía bariátrica. En dichas recomendaciones se hace especial énfasis en seguir una alimentación rica en proteínas y fibra, y baja en grasas y azúcares, con comidas pequeñas y frecuentes. Asimismo, se recomienda la actividad física diaria, dormir ocho horas, beber alcohol con moderación y no ver más de dos horas diarias de televisión", reza el ensayo.
Entre los datos obtenidos en la investigación destaca "que la pérdida de peso se produjo tanto en los familiares adultos no obesos, como en los que sí tenían sobrepeso. Al parecer, la reducción de kilos observada entre los miembros de la familia fue de un 3% del total del peso corporal... Los datos sugieren que la convivencia con un paciente que se somete a un 'by pass' gástrico y la realización de un plan de dieta estructurada, junto con el intervenido, puede tener un efecto en el peso de los miembros de la familia. Estos últimos afirmaron, además, que comían mucho menos de forma incontrolable", reconocen los investigadores.
Otro efecto colateral de la cirugía bariátrica fue el cambio en los hábitos de vida. "Los menores de la investigación además de reducir el tiempo de horas delante de la televisión, incrementaron su actividad física", agregan.
Para el doctor Adana, el estudio "es muy interesante y constata que los hábitos adquiridos por un miembro de la familia influyen en los demás. El 'by-pass' gástrico logra una pérdida intensa y duradera, pero requiere de un cambio en los estilos de vida. Precisamente, estas modificaciones suelen producirse durante el primer año, cuando el paciente está muy motivado, el problema es que luego algunos se relajan y vuelven a abandonar la dieta mediterránea y a comer fritos, alcohol y dulces... La información y la educación a los pacientes es fundamental para mantener los efectos de la cirugía y luchar contra la obesidad".
**Publicado en "EL MUNDO"
John Morton, de la Universidad de Stanford, en California (EEUU), acaba de constatar en un estudio que los familiares de los pacientes que se someten a un 'by pass' gástrico (técnica quirúrgica que permite la restricción de la ingesta de alimentos y la disminución de su absorción) también pierden peso y, además, adoptan estilos de vida saludables. Aunque éste es uno de los dos trabajos científicos existentes en la actualidad que respaldan los efectos de la cirugía bariátrica en la familia, los cirujanos que la practican desde hace tiempo llevan años observándolos.
Es el caso Juan Carlos Ruiz de Adana, del Área de Cirugía General y Digestivo y coordinador de la Unidad de Obesidad Mórbida del Hospital de Getafe en Madrid. "Recuerdo perfectamente el caso de una madre que intervenimos en la unidad cuyos hijos también padecían obesidad. Efectivamente, los cambios de vida que ella adoptó tras la intervención sirvieron para que los familiares empezaran a llevar una dieta más sana y, consecuentemente, también redujeron peso. El estudio estadounidense reafirma el hecho de que la obesidad es un problema sociofamiliar. De ahí la importancia de tratar a todos los miembros en su conjunto. Nosotros hacemos terapias de grupo con este fin cuando decimos que un paciente va a ser intervenido", aclara.
Publicado en el último 'Archives of Surgery', el estudio ha sido llevado a cabo con 35 pacientes y 35 familiares, además de 15 de los hijos, menores de 18 años. Antes de la intervención, el 60% de los familiares adultos y hasta el 73% de los niños eran obesos.
Tanto pacientes como familiares (tenían que vivir en el mismo domicilio) recibieron tres sesiones educativas antes de la intervención y, posteriormente, tras la cirugía, acudieron a varias sesiones donde repasaron los estilos de vida adoptados a lo largo del año de seguimiento que duró la investigación.
"En cada visita clínica, se proporcionó tanto a los pacientes como a los familiares la dieta estándar y el asesoramiento sobre el estilo de vida que acompaña a la cirugía bariátrica. En dichas recomendaciones se hace especial énfasis en seguir una alimentación rica en proteínas y fibra, y baja en grasas y azúcares, con comidas pequeñas y frecuentes. Asimismo, se recomienda la actividad física diaria, dormir ocho horas, beber alcohol con moderación y no ver más de dos horas diarias de televisión", reza el ensayo.
Entre los datos obtenidos en la investigación destaca "que la pérdida de peso se produjo tanto en los familiares adultos no obesos, como en los que sí tenían sobrepeso. Al parecer, la reducción de kilos observada entre los miembros de la familia fue de un 3% del total del peso corporal... Los datos sugieren que la convivencia con un paciente que se somete a un 'by pass' gástrico y la realización de un plan de dieta estructurada, junto con el intervenido, puede tener un efecto en el peso de los miembros de la familia. Estos últimos afirmaron, además, que comían mucho menos de forma incontrolable", reconocen los investigadores.
Otro efecto colateral de la cirugía bariátrica fue el cambio en los hábitos de vida. "Los menores de la investigación además de reducir el tiempo de horas delante de la televisión, incrementaron su actividad física", agregan.
Para el doctor Adana, el estudio "es muy interesante y constata que los hábitos adquiridos por un miembro de la familia influyen en los demás. El 'by-pass' gástrico logra una pérdida intensa y duradera, pero requiere de un cambio en los estilos de vida. Precisamente, estas modificaciones suelen producirse durante el primer año, cuando el paciente está muy motivado, el problema es que luego algunos se relajan y vuelven a abandonar la dieta mediterránea y a comer fritos, alcohol y dulces... La información y la educación a los pacientes es fundamental para mantener los efectos de la cirugía y luchar contra la obesidad".
**Publicado en "EL MUNDO"
Antiviral drugs may slow Alzheimer's progression
Antiviral drugs used to target the herpes virus could be effective at slowing the progression of Alzheimer's disease (AD), a new study shows. The University of Manchester scientists have previously shown that the herpes simplex virus type 1 (HSV1) is a risk factor for Alzheimer's when it is present in the brains of people who have a specific genetic risk to the disease.
AD is an incurable neurodegenerative condition affecting about 18 million people worldwide. The causes of the disease or of the abnormal protein structures seen in AD brains -- amyloid plaques and neurofibrillary tangles -- are completely unknown.
The Manchester team has established that the herpes virus causes accumulation of two key AD proteins -- β-amyloid (Aβ) and abnormally phosphorylated tau (P-tau) -- known to be the main components of plaques and tangles respectively. Both proteins are thought by many scientists to be involved in the development of the disease.
"We have found that the viral DNA in AD brains is very specifically located within amyloid plaques," said Professor Ruth Itzhaki, who led the team in the University's Faculty of Life Sciences. "This, together with the production of amyloid that the virus induces, suggests that HSV1 is a cause of toxic amyloid products and of plaques.
"Our results suggest that HSV1, together with the host genetic factor, is a major risk for AD, and that antiviral agents might be used for treating patients to slow disease progression."
Currently available antiviral agents act by targeting replication of HSV1 DNA, and so the researchers considered that they might be successful in treating AD only if the accumulation of β-amyloid and P-tau accumulation caused by the virus occurs at or after the stage at which viral DNA replication occurs.
"If these proteins are produced independently of HSV1 replication, antivirals might not be effective," said Professor Itzhaki. "We investigated this and found that treatment of HSV1-infected cells with acyclovir, the most commonly used antiviral agent, and also with two other antivirals, did indeed decrease the accumulation of β-amyloid and P-tau, as well as decreasing HSV1 replication as we would expect.
"This is the first study investigating antiviral effects on AD-like changes and we conclude that since antiviral agents reduce greatly β-amyloid and P-tau levels in HSV1-infected cells, they would be suitable for treating Alzheimer's disease. The great advantage over current AD therapies is that acyclovir would target only the virus, not the host cell or normal uninfected cells. Further, these agents are very safe and are relatively inexpensive.
"Also, by targeting a cause of Alzheimer's disease, other viral damage, besides β-amyloid and P-tau, which might be involved in the disease's pathogenesis, would also be inhibited.
"The next stage of our research -- subject to funding -- will focus on finding the most suitable antiviral agent -- or combination of two agents that operate via different mechanisms -- for use as treatment. We then need to investigate the way in which the virus and the genetic risk factor interact to cause the disease, as that might lead to further novel treatments.
"Eventually, we hope to begin clinical trials in humans but this is still some way off yet and again will require new funding."
The study, carried out with Dr Matthew Wozniak and other colleagues in the Faculty of Life Sciences, is published in the Public Library of Science (PLoS) One journal.
*Source: University of Manchester
AD is an incurable neurodegenerative condition affecting about 18 million people worldwide. The causes of the disease or of the abnormal protein structures seen in AD brains -- amyloid plaques and neurofibrillary tangles -- are completely unknown.
The Manchester team has established that the herpes virus causes accumulation of two key AD proteins -- β-amyloid (Aβ) and abnormally phosphorylated tau (P-tau) -- known to be the main components of plaques and tangles respectively. Both proteins are thought by many scientists to be involved in the development of the disease.
"We have found that the viral DNA in AD brains is very specifically located within amyloid plaques," said Professor Ruth Itzhaki, who led the team in the University's Faculty of Life Sciences. "This, together with the production of amyloid that the virus induces, suggests that HSV1 is a cause of toxic amyloid products and of plaques.
"Our results suggest that HSV1, together with the host genetic factor, is a major risk for AD, and that antiviral agents might be used for treating patients to slow disease progression."
Currently available antiviral agents act by targeting replication of HSV1 DNA, and so the researchers considered that they might be successful in treating AD only if the accumulation of β-amyloid and P-tau accumulation caused by the virus occurs at or after the stage at which viral DNA replication occurs.
"If these proteins are produced independently of HSV1 replication, antivirals might not be effective," said Professor Itzhaki. "We investigated this and found that treatment of HSV1-infected cells with acyclovir, the most commonly used antiviral agent, and also with two other antivirals, did indeed decrease the accumulation of β-amyloid and P-tau, as well as decreasing HSV1 replication as we would expect.
"This is the first study investigating antiviral effects on AD-like changes and we conclude that since antiviral agents reduce greatly β-amyloid and P-tau levels in HSV1-infected cells, they would be suitable for treating Alzheimer's disease. The great advantage over current AD therapies is that acyclovir would target only the virus, not the host cell or normal uninfected cells. Further, these agents are very safe and are relatively inexpensive.
"Also, by targeting a cause of Alzheimer's disease, other viral damage, besides β-amyloid and P-tau, which might be involved in the disease's pathogenesis, would also be inhibited.
"The next stage of our research -- subject to funding -- will focus on finding the most suitable antiviral agent -- or combination of two agents that operate via different mechanisms -- for use as treatment. We then need to investigate the way in which the virus and the genetic risk factor interact to cause the disease, as that might lead to further novel treatments.
"Eventually, we hope to begin clinical trials in humans but this is still some way off yet and again will require new funding."
The study, carried out with Dr Matthew Wozniak and other colleagues in the Faculty of Life Sciences, is published in the Public Library of Science (PLoS) One journal.
*Source: University of Manchester
Los pediatras desaconsejan que los menores de dos años vean mucho la televisión
"Tienes 10 segundos para imaginar... si no se te ha ocurrido nada, a lo mejor deberías ver menos la tele". Esta frase, que ilustraba una de las cortinillas de la mítica 'La bola de cristal', se popularizó en la España de los 80 junto a otras tan míticas como aquella de 'solo no puedo, con amigos sí'.
Casi 30 años después y en un mundo cada vez más rodeado de pantallas, el consejo cobra más actualidad que nunca. Es más, podría servir perfectamente de eslogan para las últimas recomendaciones que acaba de publicar la Asociación Americana de Pediatría.
Estas guías, que se han presentado en una reunión del organismo en Boston, desaconsejan que los niños menores de dos años pasen demasiado tiempo pegados a las pantallas. En una etapa crucial en el aprendizaje como es la primera infancia, aseguran, el juego es mucho más beneficioso para el desarrollo que la mera exposición a estímulos audiovisuales.
La Asociación Americana de Pediatría ha decidido editar estas recomendaciones después de constatar, a través de un estudio, que el 90% de los padres estadounidenses asegura que sus hijos menores de dos años ven o juegan habitualmente con algún medio electrónico. Según sus datos, la media de los pequeños de esta edad ve la televisión una o dos horas al día y casi un tercio cumple los tres años con un televisor en su propio cuarto.
Aunque no hay muchas investigaciones que hayan evaluado a fondo las consecuencias de esta alta exposición a las pantallas, los pediatras estadounidenses aseguran que "los efectos negativos potenciales son mayores que sus posibles beneficios".
"El tiempo de juego tiene más valor para el desarrollo del cerebro que los medios electrónicos. Los niños aprenden a pensar de forma creativa, a solucionar problemas y a desarrollar el razonamiento y las destrezas motoras desde edades tempranas a través del juego desestructurado. El juego libre, además, les enseña a entretenerse por sí mismos", aseguran los pediatras en sus recomendaciones.
"Los niños", continúan, "necesitan y aprenden más de su interacción con los humanos, no con las pantallas". Además, una excesiva exposición a la televisión puede interferir con los patrones del sueño y perjudica las interacciones entre padres e hijos, continúan.
Por todo esto, las recomendaciones aconsejan a los padres limitar la exposición a los medios en niños de dos años, sustituir el entretenimiento electrónico por juegos compartidos, evitar la colocación de televisores en los dormitorios infantiles y concienciarse de que el propio uso de los medios audiovisuales también puede tener un efecto negativo en los niños.
"Hoy en día, lo mejor que puede hacer por su hijo es darle la oportunidad de que juegue –tanto con usted como de forma independiente-. Los niños lo necesitan para entender cómo funciona el mundo", concluyen.
Casi 30 años después y en un mundo cada vez más rodeado de pantallas, el consejo cobra más actualidad que nunca. Es más, podría servir perfectamente de eslogan para las últimas recomendaciones que acaba de publicar la Asociación Americana de Pediatría.
Estas guías, que se han presentado en una reunión del organismo en Boston, desaconsejan que los niños menores de dos años pasen demasiado tiempo pegados a las pantallas. En una etapa crucial en el aprendizaje como es la primera infancia, aseguran, el juego es mucho más beneficioso para el desarrollo que la mera exposición a estímulos audiovisuales.
La Asociación Americana de Pediatría ha decidido editar estas recomendaciones después de constatar, a través de un estudio, que el 90% de los padres estadounidenses asegura que sus hijos menores de dos años ven o juegan habitualmente con algún medio electrónico. Según sus datos, la media de los pequeños de esta edad ve la televisión una o dos horas al día y casi un tercio cumple los tres años con un televisor en su propio cuarto.
Aunque no hay muchas investigaciones que hayan evaluado a fondo las consecuencias de esta alta exposición a las pantallas, los pediatras estadounidenses aseguran que "los efectos negativos potenciales son mayores que sus posibles beneficios".
"El tiempo de juego tiene más valor para el desarrollo del cerebro que los medios electrónicos. Los niños aprenden a pensar de forma creativa, a solucionar problemas y a desarrollar el razonamiento y las destrezas motoras desde edades tempranas a través del juego desestructurado. El juego libre, además, les enseña a entretenerse por sí mismos", aseguran los pediatras en sus recomendaciones.
"Los niños", continúan, "necesitan y aprenden más de su interacción con los humanos, no con las pantallas". Además, una excesiva exposición a la televisión puede interferir con los patrones del sueño y perjudica las interacciones entre padres e hijos, continúan.
Por todo esto, las recomendaciones aconsejan a los padres limitar la exposición a los medios en niños de dos años, sustituir el entretenimiento electrónico por juegos compartidos, evitar la colocación de televisores en los dormitorios infantiles y concienciarse de que el propio uso de los medios audiovisuales también puede tener un efecto negativo en los niños.
"Hoy en día, lo mejor que puede hacer por su hijo es darle la oportunidad de que juegue –tanto con usted como de forma independiente-. Los niños lo necesitan para entender cómo funciona el mundo", concluyen.
**Publicado en "EL MUNDO"
Protein family key to aging, cancer
The list of aging-associated proteins known to be involved in cancer is growing longer, according to research by investigators at Vanderbilt-Ingram Cancer Center and the National Institutes of Health (NIH). The new study, published Oct. 17 in Cancer Cell, identifies the protein SIRT2 as a tumor suppressor linked to gender-specific tumor development in mice. Along with two other "sirtuin" proteins previously linked to cancer, the new finding suggests the existence of a rare "family" of tumor suppressors.
Cancer is primarily a disease of aging, with the majority of cancer cases occurring in people over 50. However, the biological processes that underlie this association are not clear.
In the late-1990s, sirtuins were linked to extended lifespan observed in several species maintained on a calorically restricted diet. These nutrient-sensing proteins seemed to defend against aging-related cellular damage.
"The single most important prognostic factor in cancer is increasing age," said Gius, a professor of Radiation Oncology and associate professor of Cancer Biology at Vanderbilt-Ingram. "It seems logical that the genes that play a role in aging -- or perhaps better stated, anti-aging -- would be connected to cancer."
While at the NIH's National Cancer Institute, Gius and colleagues found that when they eliminated SIRT3 -- a sirtuin localized in the mitochondria, the cellular "power plants" -- the mice developed ER/PR positive breast tumors, the most common type of breast cancer in postmenopausal women.
In the new study, Gius' lab -- working with senior author Chu-Xia Deng, Ph.D., and colleagues at the NIH's National Institute of Diabetes and Digestive and Kidney Diseases -- investigated the physiological functions of SIRT2 by eliminating the protein in cultured cells and in mice.
They found that SIRT2-deficient mice developed tumors in multiple tissues -- and, strangely, male mice and female mice developed tumors in different tissues. Lack of SIRT2 in female mice led to mammary (breast) tumors, while male mice lacking SIRT2 developed a range of gastrointestinal tumors (in the liver, pancreas, colon and stomach).
"It's kind of a startling observation, that you'd knock a protein out, and you'd get gender-specific tumors, suggesting a physiological connection between gender and the function of sirtuin proteins" Gius said.
From human cancer data, the investigators showed that SIRT2 was also decreased in human cases of breast cancer, gastrointestinal tumors (which were not broken down by gender), and several other cancer types.
While the mechanism underlying the gender-specific tumors was not determined, the researchers did find evidence that SIRT2 acted as a tumor suppressor in cultured cells. Specifically, the protein appeared to regulate an important part of the machinery involved in cell division -- a protein complex called APC/C. Loss of SIRT2 led to "genomic instability," or an abnormal segregation of chromosomes during cell division. While the cells at first showed reduced proliferation, their growth rate gradually increased and the cells showed signs of malignant transformation.
Previous studies indicated that two other members of the sirtuin family -- SIRT1 and SIRT3 -- have tumor suppressor functions. These findings suggest that a third member of this protein family acts as a tumor suppressor.
"You don't normally find families of tumor suppressor genes," Gius said. "They're kind of lone wolves…it's just not common to find a family of (tumor suppressor) genes, especially ones connected to aging."
Because the mammary tumors that develop in female mice appear similar to the most common type of breast cancer (luminal breast cancers), Gius believes these mice could provide a much-needed animal model for that disease.
His group plans to investigate whether SIRT2 is a "driver" of luminal breast cancer and, if so, to use the mice as a model for investigating chemopreventive agents.
"Ultimately, we could possibly identify subgroups of women who might benefit from the agents we validate in mice," he said.
The research was supported by grants from the NIH's National Institute of Diabetes and Digestive and Kidney Diseases, the National Cancer Institute, the National Center for Research Resources, and from the Department of Defense.
**Source: Vanderbilt University Medical Center
Cancer is primarily a disease of aging, with the majority of cancer cases occurring in people over 50. However, the biological processes that underlie this association are not clear.
In the late-1990s, sirtuins were linked to extended lifespan observed in several species maintained on a calorically restricted diet. These nutrient-sensing proteins seemed to defend against aging-related cellular damage.
"The single most important prognostic factor in cancer is increasing age," said Gius, a professor of Radiation Oncology and associate professor of Cancer Biology at Vanderbilt-Ingram. "It seems logical that the genes that play a role in aging -- or perhaps better stated, anti-aging -- would be connected to cancer."
While at the NIH's National Cancer Institute, Gius and colleagues found that when they eliminated SIRT3 -- a sirtuin localized in the mitochondria, the cellular "power plants" -- the mice developed ER/PR positive breast tumors, the most common type of breast cancer in postmenopausal women.
In the new study, Gius' lab -- working with senior author Chu-Xia Deng, Ph.D., and colleagues at the NIH's National Institute of Diabetes and Digestive and Kidney Diseases -- investigated the physiological functions of SIRT2 by eliminating the protein in cultured cells and in mice.
They found that SIRT2-deficient mice developed tumors in multiple tissues -- and, strangely, male mice and female mice developed tumors in different tissues. Lack of SIRT2 in female mice led to mammary (breast) tumors, while male mice lacking SIRT2 developed a range of gastrointestinal tumors (in the liver, pancreas, colon and stomach).
"It's kind of a startling observation, that you'd knock a protein out, and you'd get gender-specific tumors, suggesting a physiological connection between gender and the function of sirtuin proteins" Gius said.
From human cancer data, the investigators showed that SIRT2 was also decreased in human cases of breast cancer, gastrointestinal tumors (which were not broken down by gender), and several other cancer types.
While the mechanism underlying the gender-specific tumors was not determined, the researchers did find evidence that SIRT2 acted as a tumor suppressor in cultured cells. Specifically, the protein appeared to regulate an important part of the machinery involved in cell division -- a protein complex called APC/C. Loss of SIRT2 led to "genomic instability," or an abnormal segregation of chromosomes during cell division. While the cells at first showed reduced proliferation, their growth rate gradually increased and the cells showed signs of malignant transformation.
Previous studies indicated that two other members of the sirtuin family -- SIRT1 and SIRT3 -- have tumor suppressor functions. These findings suggest that a third member of this protein family acts as a tumor suppressor.
"You don't normally find families of tumor suppressor genes," Gius said. "They're kind of lone wolves…it's just not common to find a family of (tumor suppressor) genes, especially ones connected to aging."
Because the mammary tumors that develop in female mice appear similar to the most common type of breast cancer (luminal breast cancers), Gius believes these mice could provide a much-needed animal model for that disease.
His group plans to investigate whether SIRT2 is a "driver" of luminal breast cancer and, if so, to use the mice as a model for investigating chemopreventive agents.
"Ultimately, we could possibly identify subgroups of women who might benefit from the agents we validate in mice," he said.
The research was supported by grants from the NIH's National Institute of Diabetes and Digestive and Kidney Diseases, the National Cancer Institute, the National Center for Research Resources, and from the Department of Defense.
**Source: Vanderbilt University Medical Center
Los fumadores de tabaco de liar presentan más dependencia a la nicotina y menor motivación para dejarlo
El consumo de tabaco de liar ha aumentado un 60 por ciento en 2010 y hasta un 200 por cien desde 2007 en España por factores como la crisis económica o la ley antitabaco. Sus consumidores lo prefieren por ser más barato y porque se cree que es menos dañino y adictivo que el cigarrillo convencional.
La Sociedad Española de Neumología y Cirugía Torácica (SEPAR) advierte de que este producto es "al menos tan dañino para la salud como el tabaco manufacturado" y causa una mayor adicción. La SEPAR se basa en un análisis de diferentes estudios publicado en la revista «Archivos de Bronconeumología'», que señala que el tabaco de liar contiene hasta un 22 por ciento de aditivos, frente al 10 por ciento de aditivos del manufacturado. Sin embargo, un 25 por ciento de los encuestados en estudios realizados en países anglosajones piensa que el tabaco de liar es menos dañino.
Comparado con el manufacturado, el tabaco de liar es más prevalente en hombres jóvenes, con menos recursos económicos, casados o con pareja y con menor nivel educativo. Estos fumadores presentan más dependencia a la nicotina, tienen menor motivación para dejar de fumar y creen que el tabaco de liar es menos dañino.
Según el neumólogo José Ignacio de Granda Orive, ex coordinador del Área de Tabaquismo de SEPAR y coautor de esta revisión, el tabaco de liar es "al menos tan dañino para la salud como el tabaco manufacturado". Además, los fumadores de tabaco de liar son "menos propensos a dejar de fumar, porque piensan que estos cigarrillos son menos dañinos y más naturales y, además de tener menor motivación para dejar el consumo, realizan un menor número de intentos previos de abstinencias".
Para el doctor Carlos Jiménez, actual coordinador del Área de Tabaquismo de SEPAR y coautor de esta revisión, "el problema es que, de este modo, se acerca el tabaco a los más jóvenes y (el tabaco de liar) sirve de refugio a las personas que, por motivos económicos, estarían pensando en dejarlo". Los autores de esta revisión sostienen que el auge del tabaco de liar "no se basa en una moda, sino en estrategias de venta" con las que las tabaqueras buscan no perder mercado. "En países como Estados Unidos, Canadá, Reino Unido, Australia, Francia o Noruega -destacan- el consumo de tabaco de liar también ha aumentado, debido en parte al incremento de las tasas de tabaco manufacturado".
La Sociedad Española de Neumología y Cirugía Torácica (SEPAR) advierte de que este producto es "al menos tan dañino para la salud como el tabaco manufacturado" y causa una mayor adicción. La SEPAR se basa en un análisis de diferentes estudios publicado en la revista «Archivos de Bronconeumología'», que señala que el tabaco de liar contiene hasta un 22 por ciento de aditivos, frente al 10 por ciento de aditivos del manufacturado. Sin embargo, un 25 por ciento de los encuestados en estudios realizados en países anglosajones piensa que el tabaco de liar es menos dañino.
Comparado con el manufacturado, el tabaco de liar es más prevalente en hombres jóvenes, con menos recursos económicos, casados o con pareja y con menor nivel educativo. Estos fumadores presentan más dependencia a la nicotina, tienen menor motivación para dejar de fumar y creen que el tabaco de liar es menos dañino.
Según el neumólogo José Ignacio de Granda Orive, ex coordinador del Área de Tabaquismo de SEPAR y coautor de esta revisión, el tabaco de liar es "al menos tan dañino para la salud como el tabaco manufacturado". Además, los fumadores de tabaco de liar son "menos propensos a dejar de fumar, porque piensan que estos cigarrillos son menos dañinos y más naturales y, además de tener menor motivación para dejar el consumo, realizan un menor número de intentos previos de abstinencias".
Para el doctor Carlos Jiménez, actual coordinador del Área de Tabaquismo de SEPAR y coautor de esta revisión, "el problema es que, de este modo, se acerca el tabaco a los más jóvenes y (el tabaco de liar) sirve de refugio a las personas que, por motivos económicos, estarían pensando en dejarlo". Los autores de esta revisión sostienen que el auge del tabaco de liar "no se basa en una moda, sino en estrategias de venta" con las que las tabaqueras buscan no perder mercado. "En países como Estados Unidos, Canadá, Reino Unido, Australia, Francia o Noruega -destacan- el consumo de tabaco de liar también ha aumentado, debido en parte al incremento de las tasas de tabaco manufacturado".
**AGENCIAS
Halo effect: Family members of gastric-bypass patients also lose weight, Stanford study finds
Family members of patients who have undergone surgery for weight loss may also shed several pounds themselves, as well as eat healthier and exercise more, according to a new study by researchers at Stanford University School of Medicine. A year after the 35 patients in the study had Roux-en-Y gastric bypass surgery, their obese adult family members weighed on average 8 pounds less, the researchers say.
In addition, many of the children in these families also appeared to benefit through their close association with the patient, exhibiting a lower body mass index than would have been expected given their growth curve.
The study notes that overweight women on a traditional medically supervised diet, such as Atkins or Ornish, lose between 2 and 5 percent of their body weight over 12 months. Over that same period of time, both obese men and women in the families of the surgery patients lost 3 percent of their body weight overall -- slimming down, on average, from 234 to 226 pounds.
"Family members were able to lose weight comparable to being part of a medically controlled diet simply by accompanying the bariatric surgery patient to their pre- and post-operative visits," said senior author John Morton, MD, MPH, associate professor of surgery at Stanford and director of bariatric surgery at Stanford Hospital & Clinics.
The findings will be published Oct. 17 in the Archives of Surgery. The lead author of the study is Gavitt Woodard, MD, a 2011 graduate of the Stanford School of Medicine.
The 50 adults and children who participated in the study did more than just share a house with the bariatric patients; they also, as Morton noted, accompanied the patients to all of their pre- and post-operative clinical visits, where they received dietary and lifestyle counseling. These sessions would emphasize a high-protein, high-fiber, low-fat and low-sugar diet and small, frequent meals. The sessions also set daily goals for exercise and stressed a good night's sleep, alcohol moderation and less time in front of the television.
After a year, not only did obese adult family members lose several pounds, but their waistlines also decreased on average from 47 inches to 44 inches. Weight loss among non-obese family members, however, was not significant (180 to 176 pounds), and their waist circumference held steady at an average of 39 inches. But the number of alcoholic drinks consumed by the adult family members, regardless of weight, decreased sharply, from 11.4 to 0.8 each month.
In addition, the mean body mass index among obese children in the study was lower than what would have been expected based on projected growth-curve metrics from the Centers for Disease Control and Prevention.
Adult family members made significant changes in their eating habits, with less emotional and uncontrollable eating. Both adults and children made substantial increases in their activity levels. For adult family members, metabolic equivalent task hours, a measure of physical-energy expenditure, more than doubled from 7.8 to 16.8; for children, the increase was from 12.9 to 22.4.
When behavior changes as a result of social-reinforcing conditions, it is sometimes known as a halo effect. For example, studies have found that people are more likely to quit smoking if their spouses quit, or become obese if a friend becomes obese.
Today, 26 percent of American adults and 15 percent of children are considered obese, which increases the risk of mortality related to diabetes, heart disease and cancer, the study says.
Morton noted that Stanford surgeons perform about 300 bariatric surgeries every year, and more than 200,000 are done annually in the United States.
"Can you imagine if every one of these bariatric patients were an ambassador for good health? You would have a huge, grassroots movement with bariatric surgery providing a vehicle for healthy change for patient and family alike," Morton said. "Obesity is a family disease and bariatric surgery sets the table for future, healthy family meals."
The authors conclude by saying, "Bariatric surgery programs should encourage family involvement in support groups and education sessions to capitalize on these halo effects."
Other authors of the study are Tina Hernandez-Boussard, PhD, MPH, assistant professor of surgery; and former Stanford medical students Betsy Encarnacion, MD, and Joe Peraza, MD.
The study was funded by the school's Medical Scholars Program.
**Source: Stanford University Medical Center
In addition, many of the children in these families also appeared to benefit through their close association with the patient, exhibiting a lower body mass index than would have been expected given their growth curve.
The study notes that overweight women on a traditional medically supervised diet, such as Atkins or Ornish, lose between 2 and 5 percent of their body weight over 12 months. Over that same period of time, both obese men and women in the families of the surgery patients lost 3 percent of their body weight overall -- slimming down, on average, from 234 to 226 pounds.
"Family members were able to lose weight comparable to being part of a medically controlled diet simply by accompanying the bariatric surgery patient to their pre- and post-operative visits," said senior author John Morton, MD, MPH, associate professor of surgery at Stanford and director of bariatric surgery at Stanford Hospital & Clinics.
The findings will be published Oct. 17 in the Archives of Surgery. The lead author of the study is Gavitt Woodard, MD, a 2011 graduate of the Stanford School of Medicine.
The 50 adults and children who participated in the study did more than just share a house with the bariatric patients; they also, as Morton noted, accompanied the patients to all of their pre- and post-operative clinical visits, where they received dietary and lifestyle counseling. These sessions would emphasize a high-protein, high-fiber, low-fat and low-sugar diet and small, frequent meals. The sessions also set daily goals for exercise and stressed a good night's sleep, alcohol moderation and less time in front of the television.
After a year, not only did obese adult family members lose several pounds, but their waistlines also decreased on average from 47 inches to 44 inches. Weight loss among non-obese family members, however, was not significant (180 to 176 pounds), and their waist circumference held steady at an average of 39 inches. But the number of alcoholic drinks consumed by the adult family members, regardless of weight, decreased sharply, from 11.4 to 0.8 each month.
In addition, the mean body mass index among obese children in the study was lower than what would have been expected based on projected growth-curve metrics from the Centers for Disease Control and Prevention.
Adult family members made significant changes in their eating habits, with less emotional and uncontrollable eating. Both adults and children made substantial increases in their activity levels. For adult family members, metabolic equivalent task hours, a measure of physical-energy expenditure, more than doubled from 7.8 to 16.8; for children, the increase was from 12.9 to 22.4.
When behavior changes as a result of social-reinforcing conditions, it is sometimes known as a halo effect. For example, studies have found that people are more likely to quit smoking if their spouses quit, or become obese if a friend becomes obese.
Today, 26 percent of American adults and 15 percent of children are considered obese, which increases the risk of mortality related to diabetes, heart disease and cancer, the study says.
Morton noted that Stanford surgeons perform about 300 bariatric surgeries every year, and more than 200,000 are done annually in the United States.
"Can you imagine if every one of these bariatric patients were an ambassador for good health? You would have a huge, grassroots movement with bariatric surgery providing a vehicle for healthy change for patient and family alike," Morton said. "Obesity is a family disease and bariatric surgery sets the table for future, healthy family meals."
The authors conclude by saying, "Bariatric surgery programs should encourage family involvement in support groups and education sessions to capitalize on these halo effects."
Other authors of the study are Tina Hernandez-Boussard, PhD, MPH, assistant professor of surgery; and former Stanford medical students Betsy Encarnacion, MD, and Joe Peraza, MD.
The study was funded by the school's Medical Scholars Program.
**Source: Stanford University Medical Center
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