La industria cafetera también quiere poder anunciar los beneficios de su producto. Más allá de cuestiones como el sabor y el aroma, ha conseguido que la Agencia Europea de los Alimentos (EFSA por sus siglas en inglés) avale tres alegaciones nutricionales: que ayuda a mejorar el rendimiento cognitivo, el físico y el nivel de alerta.
Claro que, para conseguir esas propiedades, no basta cualquier cantidad. En el consumo de este producto, hay tres niveles: baja (menos de 200 miligramos de cafeína al día), moderada (entre 220 y 400) y excesiva (por encima de los 400), ha indicado Ana Adán, profesora del profesora del Instituto de Investigación en Cerebro, Cognición y Conducta de la Universidad de Barcelona. Como nadie pesa la cafeína (para empezar, porque está disuelta en la infusión), el equivalente vendría a ser aproximadamente de 100 miligramos por taza.
Adán ha estado en Madrid invitada por el sector cafetero para explicar sus trabajos sobre la relación entre cafeína y rendimiento cognitivo. Y sus conclusiones son claras: dos tazas de café (200 miligramos de cafeína, aproximadamente), mejoran la capacidad de reacción y la atención. “El efecto es dosis dependiente”, dice la investigadora. Esto quiere decir que, en teoría, a más café, mejores resultados.
Claro que el consumo de este producto tiene un límite. En su empleo farmacológico (en pastillas), este se cifra en 1.200 miligramos (unas 12 tazas). Pero las personas normales y sanas no tienen por qué llegar tan lejos. En los trabajos de Adán se comparaban los resultados con dos tazas.
Pasarse con el café no es bueno. El mayor riesgo es el de una sobredosis, que produce insomnio –“sobre todo en personas de riesgo”, dice Adán-, ansiedad y taquicardias. Y luego están las personas para las que no está recomendado, que incluyen una amplia lista: las embarazadas no deben tomar más de 600 miligramos de cafeína al día, y las personas con graves dolencias cardiovasculares, gastrointestinales, epilepsia, insomnio, insuficiencia hepática y ansiedad, lo mejor es que no lo tomen.
Ahora, la investigadora está estudiando su efecto sobre la memoria (muy útil para estudiantes), o sobre la sensación –subjetiva- de somnolencia. Los ensayos demuestran que a los 30 minutos, más o menos, empieza a haber una mejoría. Esto es coherente con el tiempo que se supone que tarda la cafeína en llegar al cerebro, donde actúa saturando unos neurorreceptores que están relacionados la alerta, la capacidad de aprender, la somnolencia y el estado de ánimo. Luego su efecto, que depende de la dosis y la persona, puede durar entre tres y seis horas. Curiosamente, en las pruebas subjetivas 8donde lo que se mide es lo que responden los voluntarios), los hombres parecen más sensibles a los efectos del café que las mujeres, aunque no hay una explicación.
Uno de los temas que más preocupan a los productores es la idea de que el café puede ser adictivo. De momento, no hay evidencia al respeto, y el manual de la Asociación Americana de Psiquiatría, que es la referencia mundial, no lo considera como tal. Pero Adán admite que hay aspectos (que produce una ligerísima habituación o algo parecido al síndrome de abstinencia en los grandes consumidores) que recuerdan a lo que sucede con otras sustancias. Quizá la causa estriba en que está relacionado con el circuito dopaminérgico, con un efecto similar –aunque inmensamente inferior- al de la cocaína. Pero, de momento, este aspecto está sin demostrar.
**Publicado en "EL PAIS"
23 February 2012
A step forward in effort to regenerate damaged nerves
The carnage evident in disasters like car wrecks or wartime battles is oftentimes mirrored within the bodies of the people involved. A severe wound can leave blood vessels and nerves severed, bones broken, and cellular wreckage strewn throughout the body -- a debris field within the body itself. It's scenes like this that neurosurgeon Jason Huang, M.D., confronts every day. Severe damage to nerves is one of the most challenging wounds to treat for Huang and colleagues. It's a type of wound suffered by people who are the victims of gunshots or stabbings, by those who have been involved in car accidents -- or by soldiers injured on the battlefield, like those whom Huang treated in Iraq.
Now, back in his university laboratory, Huang and his team have taken a step forward toward the goal of repairing nerves in such patients more effectively. In a paper published in the journal PLoS ONE, Huang and colleagues at the University of Rochester Medical Center report that a surprising set of cells may hold potential for nerve transplants.
In a study in rats, Huang's group found that dorsal root ganglion neurons, or DRG cells, help create thick, healthy nerves, without provoking unwanted attention from the immune system.
The finding is one step toward better treatment for the more than 350,000 patients each year in the United States who have serious injuries to their peripheral nerves. Huang's laboratory is one of a handful developing new technologies to treat such wounds.
"These are very serious injuries, and patients really suffer, many for a very long time," said Huang, associate professor of Neurosurgery and chief of Neurosurgery at Highland Hospital, an affiliate of the University of Rochester Medical Center. "There are a variety of options, but none of them is ideal.
"Our long-term goal is to grow living nerves in the laboratory, then transplant them into patients and cut down the amount of time it takes for those nerves to work," added Huang, whose project was funded by the National Institute of Neurological Disorders and Stroke and by the University of Rochester Medical Center.
For a damaged nerve to repair itself, the two disconnected but healthy portions of the nerve must somehow find each other through a maze of tissue and connect together. This happens naturally for a very small wound -- much like our skin grows back over a small cut -- but for some nerve injuries, the gap is simply too large, and the nerve won't grow back without intervention.
For surgeons like Huang, the preferred option is to transplant nerve tissue from elsewhere in the patient's own body -- for instance, a section of a nerve in the leg -- into the wounded area. The transplanted nerve serves as scaffolding, a guide of sorts for a new nerve to grow and bridge the gap. Since the tissue comes from the patient, the body accepts the new nerve and doesn't attack it.
But for many patients, this treatment isn't an option. They might have severe wounds to other parts of the body, so that extra nerve tissue isn't available. Alternatives can include a nerve transplant from a cadaver or an animal, but those bring other challenges, such as the lifelong need for powerful immunosuppressant drugs, and are rarely used.
One technology used by Huang and other neurosurgeons is the NeuraGen Nerve Guide, a hollow, absorbable collagen tube through which nerve fibers can grow and find each other. The technology is often used to repair nerve damage over short distances less than half an inch long.
In the PLoS One study, Huang's team compared several methods to try to bridge a nerve gap of about half an inch in rats. The team transplanted nerve cells from a different type of rat into the wound site and compared results when the NeuraGen technology was was used alone or when it was paired with DRG cells or with other cells known as Schwann cells.
After four months, the team found that the tubes equipped with either DRG or Schwann cells helped bring about healthier nerves. In addition, the DRG cells provoked less unwanted attention from the immune system than the Schwann cells, which attracted twice as many macrophages and more of the immune compound interferon gamma.
While both Schwann and DRG cells are known players in nerve regeneration, Schwann cells have been considered more often as potential partners in the nerve transplantation process, even though they pose considerable challenges because of the immune system's response to them.
"The conventional wisdom has been that Schwann cells play a critical role in the regenerative process," said Huang, who is a scientist in the Center for Neural Development and Disease. "While we know this is true, we have shown that DRG cells can play an important role also. We think DRG cells could be a rich resource for nerve regeneration."
*Source: University of Rochester Medical Center
Now, back in his university laboratory, Huang and his team have taken a step forward toward the goal of repairing nerves in such patients more effectively. In a paper published in the journal PLoS ONE, Huang and colleagues at the University of Rochester Medical Center report that a surprising set of cells may hold potential for nerve transplants.
In a study in rats, Huang's group found that dorsal root ganglion neurons, or DRG cells, help create thick, healthy nerves, without provoking unwanted attention from the immune system.
The finding is one step toward better treatment for the more than 350,000 patients each year in the United States who have serious injuries to their peripheral nerves. Huang's laboratory is one of a handful developing new technologies to treat such wounds.
"These are very serious injuries, and patients really suffer, many for a very long time," said Huang, associate professor of Neurosurgery and chief of Neurosurgery at Highland Hospital, an affiliate of the University of Rochester Medical Center. "There are a variety of options, but none of them is ideal.
"Our long-term goal is to grow living nerves in the laboratory, then transplant them into patients and cut down the amount of time it takes for those nerves to work," added Huang, whose project was funded by the National Institute of Neurological Disorders and Stroke and by the University of Rochester Medical Center.
For a damaged nerve to repair itself, the two disconnected but healthy portions of the nerve must somehow find each other through a maze of tissue and connect together. This happens naturally for a very small wound -- much like our skin grows back over a small cut -- but for some nerve injuries, the gap is simply too large, and the nerve won't grow back without intervention.
For surgeons like Huang, the preferred option is to transplant nerve tissue from elsewhere in the patient's own body -- for instance, a section of a nerve in the leg -- into the wounded area. The transplanted nerve serves as scaffolding, a guide of sorts for a new nerve to grow and bridge the gap. Since the tissue comes from the patient, the body accepts the new nerve and doesn't attack it.
But for many patients, this treatment isn't an option. They might have severe wounds to other parts of the body, so that extra nerve tissue isn't available. Alternatives can include a nerve transplant from a cadaver or an animal, but those bring other challenges, such as the lifelong need for powerful immunosuppressant drugs, and are rarely used.
One technology used by Huang and other neurosurgeons is the NeuraGen Nerve Guide, a hollow, absorbable collagen tube through which nerve fibers can grow and find each other. The technology is often used to repair nerve damage over short distances less than half an inch long.
In the PLoS One study, Huang's team compared several methods to try to bridge a nerve gap of about half an inch in rats. The team transplanted nerve cells from a different type of rat into the wound site and compared results when the NeuraGen technology was was used alone or when it was paired with DRG cells or with other cells known as Schwann cells.
After four months, the team found that the tubes equipped with either DRG or Schwann cells helped bring about healthier nerves. In addition, the DRG cells provoked less unwanted attention from the immune system than the Schwann cells, which attracted twice as many macrophages and more of the immune compound interferon gamma.
While both Schwann and DRG cells are known players in nerve regeneration, Schwann cells have been considered more often as potential partners in the nerve transplantation process, even though they pose considerable challenges because of the immune system's response to them.
"The conventional wisdom has been that Schwann cells play a critical role in the regenerative process," said Huang, who is a scientist in the Center for Neural Development and Disease. "While we know this is true, we have shown that DRG cells can play an important role also. We think DRG cells could be a rich resource for nerve regeneration."
*Source: University of Rochester Medical Center
Can consuming caffeine while breastfeeding harm your baby?
Babies are not able to metabolize or excrete caffeine very well, so a breastfeeding mother's consumption of caffeine may lead to caffeine accumulation and symptoms such as wakefulness and irritability, according to an interview with expert Ruth Lawrence, MD, published in Journal of Caffeine Research, a peer-reviewed journal from Mary Ann Liebert, Inc. Caffeine is found in a wide range of products in addition to coffee, tea, and chocolate, including soft drinks, sports drinks, and some over-the-counter medications. In a provocative discussion with Dr. Ruth Lawrence, Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Jack E. James, PhD, Editor-in-Chief of Journal of Caffeine Research, asks a variety of probing questions. Is there a safe level of caffeine intake while breastfeeding? Are there potential long-term effects of caffeine exposure on development and intellect? Can a baby whose mother consumed caffeine during pregnancy experience withdrawal if she then abstains from caffeine while breastfeeding? Dr. Lawrence bases her responses on the scientific and medical evidence related to caffeine exposure in breastfed babies, and distinguishes between what is and what is not well understood in this developing field of study.
"Usually a mother, particularly if she is breastfeeding, is cautioned to limit her caffeine intake," says Dr. Lawrence, who is Editor-in-Chief of the peer-reviewed journal Breastfeeding Medicine. After giving birth, mothers "should consume all things in moderation and try to avoid the excesses that might really add up to a lot of caffeine."
"Usually a mother, particularly if she is breastfeeding, is cautioned to limit her caffeine intake," says Dr. Lawrence, who is Editor-in-Chief of the peer-reviewed journal Breastfeeding Medicine. After giving birth, mothers "should consume all things in moderation and try to avoid the excesses that might really add up to a lot of caffeine."
Newly identified oral bacterium linked to heart disease and meningitis
A novel bacterium, thought to be a common inhabitant of the oral cavity, has the potential to cause serious disease if it enters the bloodstream, according to a study in the International Journal of Systematic and Evolutionary Microbiology. Its identification will allow scientists to work out how it causes disease and evaluate the risk that it poses. The bacterium was identified by researchers at the Institute of Medical Microbiology of the University of Zurich and has been named Streptococcus tigurinus after the region of Zurich where it was first recognised. S. tigurinus was isolated from blood of patients suffering from endocarditis, meningitis and spondylodiscitis (inflammation of the spine). It bears a close resemblance to other Streptococcus strains that colonise the mouth. Bleeding gums represent a possible route of entry for oral bacteria into the bloodstream.
The similarity of S. tigurinus to other related bacteria has meant that it has existed up until now without being identified. Its recent identification is clinically important, explained Dr Andrea Zbinden who led the study. "Accurate identification of this bacterium is essential to be able to track its spread. Further research must now be done to understand the strategies S. tigurinus uses to successfully cause disease. This will allow infected patients to be treated quickly and with the right drug."
Dr Zbinden said that while the discovery of the bacterium is no cause for alarm, it is important that it is recognised and the risk is quantified. "This bacterium seems to have a natural potential to cause severe disease and so it's important that clinicians and microbiologists are aware of it," she said. "The next step is to work out exactly how common this bacterium is in the oral cavity and what risk it poses. Immunosuppression, abnormal heart valves, dental surgeries or chronic diseases are common predisposing factors for blood infections by this group of bacteria. However, the specific risk factors for S. tigurinus remain to be determined."
The similarity of S. tigurinus to other related bacteria has meant that it has existed up until now without being identified. Its recent identification is clinically important, explained Dr Andrea Zbinden who led the study. "Accurate identification of this bacterium is essential to be able to track its spread. Further research must now be done to understand the strategies S. tigurinus uses to successfully cause disease. This will allow infected patients to be treated quickly and with the right drug."
Dr Zbinden said that while the discovery of the bacterium is no cause for alarm, it is important that it is recognised and the risk is quantified. "This bacterium seems to have a natural potential to cause severe disease and so it's important that clinicians and microbiologists are aware of it," she said. "The next step is to work out exactly how common this bacterium is in the oral cavity and what risk it poses. Immunosuppression, abnormal heart valves, dental surgeries or chronic diseases are common predisposing factors for blood infections by this group of bacteria. However, the specific risk factors for S. tigurinus remain to be determined."
*Source: Society for General Microbiology
El análisis de heces es tan eficaz como la colonoscopia, según una investigación
Para detectar un cáncer de colon, el tumor maligno más extendido y el segundo en mortalidad en España, no hace falta pasar por el mal trago de una colonoscopia. Según un estudio multicéntrico español, publicado en la revista médica «The New England Journal of Medicine», las pruebas de sangre en heces son tan efectivas como las colonoscopias a la hora de detectar esta enfermedad y resultan «mucho más baratas y menos invasivas», según explicó ayer en declaraciones a ABC el doctor Antoni Castells, director del Instituto de Enfermedades Digestivas del Hospital Clínic de Barcelona, que ha liderado el estudio junto al doctor Enrique Quintero, responsable del Servicio de Digestivo del Hospital Universitario de Canarias, en Tenerife.
Las conclusiones de la investigación, en la que han participado 60.000 pacientes de entre 50 y 70 años procedentes de ocho comunidades autónomas, rompe con el mito de que la única detección posible de esta enfermedad pasa por esta prueba tan invasiva, que conlleva riesgos asociados como la perforación intestinal o las hemorragias. «Es importante destacar que son un porcentaje poco elevado de pacientes los que sufren estos problemas, aunque debe tenerse en cuenta», apunta Castells, quien subraya la «percepción negativa» que tiene la población sobre esta prueba.
-Método no invasivo
«Cuando empezamos a reclutar población para el estudio hace unos dos años, había mucha más gente que se ofrecía para la exploración inmunológica de la sangre en heces que para la colonoscopia», afirma el especialista. La gran aportación del estudio es que hay un método no invasivo para detectar la enfermedad, un filtro similar al de las mamografías cuando hablamos de cáncer de mama.
«Hasta ahora había cierta tendencia a pensar que quizá para encontrar un cáncer de colon debía pagarse el peaje dela colonoscopia; ahora se ha desmontado este mito», asegura el digestólogo del Hospital Clínic.
Otra de las conclusiones relevantes de la investigación, financiada por la Asociación Española contra el Cáncer (Aecc) y el Instituto de Salud Carlos III, es que el análisis de las heces no detecta el 50% de los pólipos, que pueden desembocar en un proceso de malignización.
«Los pólipos acaban malignizando a los cinco años, aunque lo más probable es que si no te detectan en la primera analítica, lo hagan en la segunda o la tercera», apunta Castells, quien recuerda que este tipo de prueba, la más generalizada en Europa, requiere repetirla cada dos años.
«De este modo, en diez años, que es un período normal de seguimiento, a una persona le han realizado la prueba unas cinco veces», asegura el especialista, quien recuerda que los resultados del informe que ahora presenta recogen el estudio de solo dos años.
-Ante la duda, colonoscopia
Las conclusiones del estudio avalan, según Castells, la estrategia del análisis de las heces como fórmula más efectiva, más económica, y menos invasiva para realizar un control de la enfermedad a nivel poblacional.
«Eso no significa que, una vez detectado el cáncer, la persona deba realizarse una colonoscopia», concluye el experto del Clínic.
**Publicado en "VOCENTO"
Las conclusiones de la investigación, en la que han participado 60.000 pacientes de entre 50 y 70 años procedentes de ocho comunidades autónomas, rompe con el mito de que la única detección posible de esta enfermedad pasa por esta prueba tan invasiva, que conlleva riesgos asociados como la perforación intestinal o las hemorragias. «Es importante destacar que son un porcentaje poco elevado de pacientes los que sufren estos problemas, aunque debe tenerse en cuenta», apunta Castells, quien subraya la «percepción negativa» que tiene la población sobre esta prueba.
-Método no invasivo
«Cuando empezamos a reclutar población para el estudio hace unos dos años, había mucha más gente que se ofrecía para la exploración inmunológica de la sangre en heces que para la colonoscopia», afirma el especialista. La gran aportación del estudio es que hay un método no invasivo para detectar la enfermedad, un filtro similar al de las mamografías cuando hablamos de cáncer de mama.
«Hasta ahora había cierta tendencia a pensar que quizá para encontrar un cáncer de colon debía pagarse el peaje dela colonoscopia; ahora se ha desmontado este mito», asegura el digestólogo del Hospital Clínic.
Otra de las conclusiones relevantes de la investigación, financiada por la Asociación Española contra el Cáncer (Aecc) y el Instituto de Salud Carlos III, es que el análisis de las heces no detecta el 50% de los pólipos, que pueden desembocar en un proceso de malignización.
«Los pólipos acaban malignizando a los cinco años, aunque lo más probable es que si no te detectan en la primera analítica, lo hagan en la segunda o la tercera», apunta Castells, quien recuerda que este tipo de prueba, la más generalizada en Europa, requiere repetirla cada dos años.
«De este modo, en diez años, que es un período normal de seguimiento, a una persona le han realizado la prueba unas cinco veces», asegura el especialista, quien recuerda que los resultados del informe que ahora presenta recogen el estudio de solo dos años.
-Ante la duda, colonoscopia
Las conclusiones del estudio avalan, según Castells, la estrategia del análisis de las heces como fórmula más efectiva, más económica, y menos invasiva para realizar un control de la enfermedad a nivel poblacional.
«Eso no significa que, una vez detectado el cáncer, la persona deba realizarse una colonoscopia», concluye el experto del Clínic.
**Publicado en "VOCENTO"
Injectable gel could repair tissue damaged by heart attack
University of California, San Diego researchers have developed a new injectable hydrogel that could be an effective and safe treatment for tissue damage caused by heart attacks. The study by Karen Christman and colleagues appears in the Feb. 21 issue of the Journal of the American College of Cardiology. Christman is a professor in the Department of Bioengineering at the UC San Diego Jacobs School of Engineering and has co-founded a company, Ventrix, Inc., to bring the gel to clinical trials within the next year.
Therapies like the hydrogel would be a welcome development, Christman explained, since there are an estimated 785,000 new heart attack cases in the United States each year, with no established treatment for repairing the resulting damage to cardiac tissue.
The hydrogel is made from cardiac connective tissue that is stripped of heart muscle cells through a cleansing process, freeze-dried and milled into powder form, and then liquefied into a fluid that can be easily injected into the heart. Once it hits body temperature, the liquid turns into a semi-solid, porous gel that encourages cells to repopulate areas of damaged cardiac tissue and to preserve heart function, according to Christman. The hydrogel forms a scaffold to repair the tissue and possibly provides biochemical signals that prevent further deterioration in the surrounding tissues.
"It helps to promote a positive remodeling-type response, not a pro-inflammatory one in the damaged heart," Christman said.
What's more, the researchers' experiments show that the gel also can be injected through a catheter, a method that is minimally invasive and does not require surgery or general anesthesia.
New, unpublished work by her research team suggests that the gel can improve heart function in pigs with cardiac damage, which brings this potential therapy one step closer to humans, said Christman.
There are few injectable cardiac therapies in development designed to be used in large animals such as pigs, which have a heart that is similar in size and anatomy to the human heart, Christman explained. "Most of the materials that people have looked at have been tested in rats or mice, and they are injectable via a needle and syringe. However, almost all of them are not compatible with catheter delivery and would gel too quickly, clogging the catheter during the procedure.
In experiments with rats, the gel was not rejected by the body and did not trigger arrhythmic heart beating, providing some assurance that the gel will be similarly safe for humans, the researchers note.
Therapies like the hydrogel would be a welcome development, Christman explained, since there are an estimated 785,000 new heart attack cases in the United States each year, with no established treatment for repairing the resulting damage to cardiac tissue.
The hydrogel is made from cardiac connective tissue that is stripped of heart muscle cells through a cleansing process, freeze-dried and milled into powder form, and then liquefied into a fluid that can be easily injected into the heart. Once it hits body temperature, the liquid turns into a semi-solid, porous gel that encourages cells to repopulate areas of damaged cardiac tissue and to preserve heart function, according to Christman. The hydrogel forms a scaffold to repair the tissue and possibly provides biochemical signals that prevent further deterioration in the surrounding tissues.
"It helps to promote a positive remodeling-type response, not a pro-inflammatory one in the damaged heart," Christman said.
What's more, the researchers' experiments show that the gel also can be injected through a catheter, a method that is minimally invasive and does not require surgery or general anesthesia.
New, unpublished work by her research team suggests that the gel can improve heart function in pigs with cardiac damage, which brings this potential therapy one step closer to humans, said Christman.
There are few injectable cardiac therapies in development designed to be used in large animals such as pigs, which have a heart that is similar in size and anatomy to the human heart, Christman explained. "Most of the materials that people have looked at have been tested in rats or mice, and they are injectable via a needle and syringe. However, almost all of them are not compatible with catheter delivery and would gel too quickly, clogging the catheter during the procedure.
In experiments with rats, the gel was not rejected by the body and did not trigger arrhythmic heart beating, providing some assurance that the gel will be similarly safe for humans, the researchers note.
**Source: University of California, San Diego
España: Sanidad acuerda el primer calendario único de vacunas
España contará con un calendario único de vacunación, gracias al principio de acuerdo que el Ministerio de Sanidad logró arrancar ayer a las comunidades autónomas. Se trata de un paso histórico para los pediatras que llevaban diez años intentando unificar los calendarios de vacunación de las 17 comunidades autónomas. Ninguno de ellos coincide ni en la edad en la que se administran ni en el número de enfermedades contra las que se protege a los niños. El pacto se selló ayer en la reunión previa al Consejo Interterritorial de Salud de la semana próxima.
El compromiso, que ratificarán los consejeros de Sanidad, se tiene. Pero aún no se sabe cómo será ese calendario único. De momento, todas las autonomías adelantarán la triple vírica (sarampión, rubéola y paperas) a los 12 meses. Queda por saber si se extenderá la vacunación de varicela o neumococo que ya financian algunas autonomías.
**AGENCIAS
El compromiso, que ratificarán los consejeros de Sanidad, se tiene. Pero aún no se sabe cómo será ese calendario único. De momento, todas las autonomías adelantarán la triple vírica (sarampión, rubéola y paperas) a los 12 meses. Queda por saber si se extenderá la vacunación de varicela o neumococo que ya financian algunas autonomías.
**AGENCIAS
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