Crean un 'detector del dolor' basado en la resonancia magnética funcional.

Hay muchas cosas que actualmente sólo se pueden medir indirectamente. Una de ellas es el dolor, que constituye una experiencia subjetiva. El gran reto es conseguir un método para calibrarlo de forma directa y objetiva. El 'dolorímetro' perfecto aún no existe, pero se están produciendo avances importantes. El último de ellos es un sistema que identifica las zonas del cerebro que se activan ante el dolor.
"¿Dónde le duele? ¿Con qué intensidad?". Estas y otras preguntas mucho más específicas son las que ayudan a los médicos a valorar lo que sufren sus pacientes. Existen escalas y cuestionarios científicamente validados que evalúan el relato del propio paciente. En la mayoría de los casos, esta aproximación proporciona información suficiente para decidir cuál es el mejor tratamiento. Pero, por multitud de razones, no es infalible. La percepción del 'tormento' varía en función de la persona y de la cultura. Además, a veces resulta muy complicado distinguir claramente el dolor de estados emocionales como la ansiedad o la depresión. Finalmente, hay personas que no pueden expresar de ninguna forma su padecimiento. Tal es el caso de los niños menores de seis años y los ancianos con demencia.
El detector de dolor ingeniado por el equipo de investigadores capitaneado por Sean Mackey, jefe de la División de Manejo del Dolor de la Facultad de Medicina de la Universidad de Stanford (Estados Unidos), se basa en la técnica de imagen conocida como resonancia magnética funcional. Con esta tecnología se 'fotografió' la actividad cerebral de 24 individuos mientras eran sometidos a estímulos dolorosos y neutros aplicándoles calor en el antebrazo. Se introdujeron los datos obtenidos en un ordenador que, con un programa especial, elaboró un modelo capaz de identificar a aquellos sujetos que experimentaron dolor. Y lo hizo con un porcentaje de aciertos del 81%. El programa localizó cinco áreas de la corteza cerebral cuya actividad se incrementaba con el dolor.
Los investigadores consideran que sus resultados, publicados en 'PLoS ONE', son muy prometedores, pero advierten de que su sistema aún está muy lejos de la práctica clínica. Un experto español en dolor, Francisco Reinoso, jefe de sección de Anestesia Pediátrica del Hospital La Paz de Madrid, coincide con esta apreciación. Reconoce que, en estos momentos, "la herramienta más fiable que tenemos para medir la subjetividad es la resonancia magnética funcional". Sin embargo, llevarla a la práctica diaria requeriría realizar más estudios para confirmar su utilidad y, de todos modos, resultaría demasiado caro y laborioso.
El doctor Reinoso señala que el uso del método desarrollado en Stanford no valdría para todos los pacientes. Es más, no serviría en muchos de los casos en los que los cuestionarios están descartados: los bebés y los ancianos con problemas cognitivos. "La demencia produce atrofia de la corteza cerebral y en los niños muy pequeños hay una inmadurez de esta zona". Por lo tanto, en estos dos grupos se observaría una activación cerebral que no responde al patrón habitual.

-Otras opciones
Pero para los benjamines y los mayores existen otras alternativas. Fundamentalmente, se valoran los cambios fisiológicos, vegetativos y conductuales. Por ejemplo, se mide la frecuencia cardiaca, la tensión arterial, la frecuencia respiratoria, la dilatación pupilar, la sudoración... Todos ellos se alteran cuando se sufre dolor. "El problema es que son parámetros muy sensibles, pero poco específicos", recalca el experto. Así, un recién nacido también puede tener la frecuencia cardiaca y la tensión elevadas porque tiene hambre. Por eso, los médicos se fijan, asimismo, en otros aspectos. Si un bebé recién operado ya ha comido y se encuentra al abrigo de sus progenitores, lo más probable es que la modificación de sus constantes se deba al dolor. Con los ancianos se actúa de forma similar.
En el resto de los casos, lo más habitual es pedir al paciente que describa su dolor utilizando una escala del cero al 10. "Es la más útil, pero muchos experimentos muestran que un mismo estímulo doloroso puede ser calificado de forma muy diferente por distintas personas. Y no es que estén mintiendo o exagerando", puntualiza Reinoso.
El especialista apunta que influyen aspectos como el contexto en el que se produzca la lesión. "No es lo mismo que alguien se dé un golpe salvando a otra persona de un peligro que el hecho de que una mujer reciba ese mismo golpe como consecuencia de un acto de violencia de género", cita a modo de ejemplo. El componente emocional hace que, en el primer caso, el dolor llegue a desaparecer, mientras que en el segundo se percibirá con mucha más intensidad.
La medición objetiva es un reto difícil, pero no inalcanzable. En opinión del médico español, se logrará cuando se pueda determinar "la actividad que se produce en los núcleos laterales del tálamo". Dicha región cerebral es la que "recoge específicamente la información pura y dura relacionada con un estímulo doloroso, sin componente subjetivo". Este 'santo grial' aún está fuera del alcance de los investigadores; los motivos son tecnológicos y éticos. En animales de experimentación se ha conseguido estudiar esta zona gracias a métodos agresivos: introduciendo electrodos en sus cerebros.

**publicado en "EL MUNDO"

Institute for Aging Research study finds Boston's elderly homeless sicker than others

A striking portrait of the health of Boston's elderly homeless population is emerging from a new study by the Institute for Aging Research of Hebrew SeniorLife, an affiliate of Harvard Medical School. The study finds that homeless seniors in Boston experience higher rates of geriatric syndromes, including functional decline, falls, frailty and depression, than seniors in the general population and that many of these conditions may be easily treated if detected. "Our study shows that older homeless adults in Boston have higher rates of geriatric syndromes compared to the general population," says lead author Rebecca T. Brown, M.D., a research fellow at the Institute for Aging Research at the time the study was conducted. "Many of these syndromes are treatable if addressed proactively."
Researchers from the Institute for Aging Research, Beth Israel Deaconess Medical Center, and the Boston Health Care for the Homeless Program collaborated on the study, which was funded by The John A. Hartford Foundation and the National Institutes of Health.
Published online in the Journal of Geriatric Internal Medicine, the study found that geriatric conditions were common in homeless adults ages 50 to 69, including problems with performing daily activities, walking, vision and hearing, as well as falls, frailty, depression and urinary incontinence. The research team examined data from interviews and physical examinations of 247 homeless adults over a six-month period at eight Boston homeless shelters and compared the information with three large population-based study cohorts.
Thirty percent of the homeless seniors reported difficulty performing at least one activity of daily living, such as bathing and dressing, and more than half said they fell in the prior year. Nearly 40 percent experienced major depression, and one-quarter suffered from cognitive decline, primarily impaired executive function (decision-making, planning and judgment).
According to previous studies, the average age of the homeless population in the United States is increasing. Nearly one-third of homeless adults in the U.S. today are over age 50, compared to 11 percent in the 1990s. In Boston, more than 7,000 men, women and children are homeless, according to the city's latest homeless census. Eighteen percent of homeless men in Boston and 15 percent of homeless women are older than 55. Despite this trend, little is known about geriatric syndromes among the growing elderly homeless population. The Institute for Aging Research study is the first to rigorously characterize the presence of geriatric syndromes in older homeless adults.
"Clinicians who care for homeless adults should screen them for age-related conditions earlier than patients who have not experienced homelessness," says senior author Susan L. Mitchell, M.D., M.P.H., a senior scientist at the Institute for Aging Research. "This study suggests that homeless adults aged 50 and older have high rates of common geriatric conditions that are usually found in patients 65 and older."
Dr. Brown says that many of these conditions are easily treated if they are detected. Addressing these issues proactively, she adds, may reduce adverse outcomes and acute hospitalizations. She also says that screening and standard treatment for geriatric syndromes is warranted for homeless adults over the age of 50 who have access to health care, despite the challenges of delivering health-care services to this population.
Programs like Boston Health Care for the Homeless, which has provided high-quality health-care services in the Greater Boston area for more than 25 years, are key to ensuring that homeless individuals, young and old alike, receive needed medical and dental care.

*Source: Hebrew SeniorLife Institute for Aging Research

Las enfermedades no transmisibles matan a 36 millones de personas al año

Son la mayor causa de muerte del mundo. Los organismos sanitarios los llaman los "cuatro asesinos", responsables del 63% de fallecimientos anuales. Y los tienen bien "fichados". Sus nombres son cáncer, enfermedades cardiovasculares, trastornos respiratorios crónicos y diabetes. Juntos provocan tres de cada cinco decesos. Pero se pueden evitar muchos de ellos.
"Se conocen los problemas y también las soluciones. Ha llegado la hora de estas últimas. Los líderes tienen una oportunidad única los próximos días en Nueva York, donde por segunda vez en la historia de Naciones Unidas se celebrará una Asamblea General centrada en temas sanitarios", afirma el doctor Ala Alwan, de la Organización Mundial de la Salud (OMS). "La prevención, el tratamiento y la atención son las claves", añade.
Antes de la cumbre, la OMS ha publicado un informe sobre el mapa global de las enfermedades no transmisibles. Con datos de 193 países de distintos ingresos, el documento recoge que, de media, las enfermedades cardiovasculares son responsables del 48% de las muertes en el mundo, los distintos tipos de cáncer del 21%, los trastornos respiratorios crónicos del 12% y la diabetes del 3%. De los 57 millones de fallecimientos que se registraron en 2008 -año al que corresponden las cifras-, 36 millones fueron causados por estas patologías.
Más de nueve millones de estas muertes se producen de forma prematura, en personas que aún no han cumplido los 60 años. Y éstas, que afectan al 22% de los hombres y al 35% de las mujeres de los países de bajos ingresos y al 8% de hombres y 10% de mujeres de los países ricos, son las que podrían prevenirse más fácilmente, según el organismo. Basta con medidas eficaces para reducir los principales factores de riesgo, que son el tabaco, el abuso de alcohol, la mala alimentación y la falta de ejercicio físico, que provocan un aumento de la tensión, del colesterol y de los niveles de glucosa en sangre y, a partir de ahí, el desarrollo de las enfermedades citadas.
"Mejorar la situación no es sólo una cuestión de dinero, sino de definir bien las estrategias más eficaces y de un compromiso político y social", declara Alwan.

-Nuevas prioridades
La proporción de muerte prematura es tres veces más alta en los países pobres. Como reconoce la directora de la OMS, Margaret Chan, "estamos en un mundo acosado por las crisis. A una le sucede otra y son extremadamente contagiosas y profundamente injustas en sus consecuencias, porque afectan de forma desproporcionada a países que nada tienen que ver con las causas que las han provocado".
Por eso insiste en que "en estos tiempos de austeridad financiera es cuando los programas de salud pública deben mostrar su eficiencia y su eficacia. Debe dejar de ser una frase para convertirse en el principal objetivo".
Entre los factores de riesgo, el tabaco es más común en los lugares con pocos recursos, mientras que la inactividad física es mucho más alta en los países desarrollados. De hecho, el 41% de los varones y el 48% de las féminas que viven en países ricos no realizan ningún ejercicio físico, frente al 18% de los hombres y el 21% de las mujeres de los países pobres.
"Si algo nos ha enseñado esta cascada de calamidades, crisis y sorpresas desagradables es que tenemos que reconsiderar la manera en la que abordar los retos en el siglo XXI. Entre ellos los retos sanitarios, que no pueden esperar", concluye Chan.

**Publicado en "EL MUNDO"

Study examines risk of aortic complications among patients with common congenital heart valve defect

While the incidence of the life-threatening condition of aortic dissection is significantly higher than in the general population, it remains low among patients with the congenital heart defect, bicuspid aortic valve; however, the incidence of aortic aneurysms is significantly high, according to a study in the September 14 issue of JAMA. Bicuspid aortic valve (BAV; defect of the aortic valve that results in the formation of two flaps that open and close, instead of the normal three) is the most common congenital heart defect, with the most serious complication from this condition (due to the high risk of death) being aortic dissection (a tear involving the layers of the wall of the aorta). "… it is estimated that BAV is responsible for more deaths than all other congenital heart defects combined. Consequently, carriers live under the threat of sudden death," according to background information in the article. However, long-term, population-based data are lacking on the incidence of severe aortic complications among patients with BAV.
Hector I. Michelena, M.D., of the Mayo Clinic, Rochester, M inn., and colleagues conducted a study to determine the incidence of aortic complications among patients with BAV and in the general BAV population. The researchers analyzed long-term follow-up data of residents in Olmsted County, Minn., diagnosed with BAV by echocardiography from 1980 to 1999 and searched for aortic complications of patients whose bicuspid valves had gone undiagnosed. The last year of follow-up was 2008-2009. The study included 416 patients with BAV, with average follow-up of 16 years.
Over the study period, aortic dissection occurred in 2 of the 416 patients and the 25-year cohort risk of aortic dissection after echocardiographic diagnosis was 0.5 percent. In a comparison of incident rates, patients with BAV had a 8.4 times increased risk of aortic dissection compared with the county's general population, however, the absolute risk remained low. "The low aortic dissection incidence and lack of association with a detectable reduction in survival is reassuring," the authors write.
Of 384 patients without aortic aneurysms at the beginning of the study, 49 developed aneurysms at follow-up. The 25-year risk of aneurysm formation among BAV patients was 26 percent. Analysis of incidence rates indicated these patients had a 86 times higher risk of aneurysm formation compared with the general population. After aneurysm diagnosis, the 15-year risks of aortic surgery and aortic dissection were 46 percent and 7 percent, respectively. The 25-year risk of aortic surgery after BAV diagnosis was 25 percent.
The researchers also found that the dissection incidence was higher in patients older than 50 years and higher in those with baseline aortic aneurysms, "highlighting the importance of close monitoring and current guideline implementation in these subgroups."
Also, patients with BAV had a 25-year risk of valve replacement of 53 percent. "Our study confirms that aortic valve replacement remains the most common complication of patients with BAV. This highlights the importance of early recognition of BAV by careful cardiac auscultation [listening for sounds made by internal organs to aid in the diagnosis of certain disorders] in order to prevent heart failure due to late valvular surgery referrals, as well as potentially to prevent dissection by elective aorta surgical repair," the authors write.
"Research efforts should concentrate on elucidating biological pathways of BAV aortopathy [disease of the aorta] amenable to medical treatment, as well as identifying nonsize markers for refining risk prediction of aortic dissection in these patients," the researchers conclude.

*Source: JAMA and Archives Journals

Nada 226 Kms por el río Támesis para fines benéficos

El cómico inglés David Walliams, de 40 años, cumplió esta iniciativa durante ocho días para recaudar un millón de libras esterlina, que se donarán para la investigación sobre enfermedades, ha informado 'Reuters'.

Pituitary hormone TSH found to directly influence bone growth

Researchers at Mount Sinai School of Medicine have found that thyroid-stimulating hormone (TSH), a hormone produced in the anterior pituitary gland that regulates endocrine function in the thyroid gland, can promote bone growth independent of its usual thyroid functions. The research suggests that TSH, or drugs that mimic its affect on bone, may be key to possible future treatments for osteoporosis and other conditions involving bone loss, such as cancer. The findings were published online this week in Proceedings of the National Academy of Sciences. The same Mount Sinai researchers had previously published research showing that TSH inhibits the creation of osteoclasts, a type of cell that removes bone tissue from the body. With this new study, however, the researchers have established for the first time that TSH also activates osteoblasts, which are cells responsible for bone formation.
"There are relatively few treatments right now for osteoporosis, and virtually all of them focus on limiting osteoclasts -- that is, fighting the loss of existing bone," said Terry F. Davies, MD, FRCP, FACE, Florence and Theodore Baumritter Professor of Medicine, Mount Sinai School of Medicine. "However, our study shows that future progress in osteoporosis therapies may hinge on medications that can mimic the effects of TSH and promote the growth of new bone. The key will be to develop TSH analogs that would activate osteoblasts and yet not affect the thyroid gland the way TSH itself does."
"Osteoporosis is really an imbalance in the functions that create and destroy bone in the body," said Mone Zaidi, MD, PhD, FRCP, FACE, Hon MD, Professor of Medicine, and Director of the Mount Sinai Bone Program, Mount Sinai School of Medicine. "Our findings indicate that there may be a novel new method for addressing the lack of bone production. Our discovery that TSH causes bone growth also represents a new way of thinking about the role of certain glands and how they operate."
About 60 million people in the United States have symptoms of osteoporosis, and often they are unaware of the condition until they experience a broken bone or shrinkage of their skeleton. The disease affects women more often than men, and risk factors include aging; low body weight; low levels of the sex hormone estrogen; smoking; and some medications.
Dr. Zaidi is a named inventor of a pending patent application related to the use of TSH in the inhibition of TNF activity. This patent has been filed by the Mount Sinai School of Medicine. In the event the patent is licensed, Dr. Zaidi would be entitled to a share of a any proceeds Mount Sinai School of Medicine receives from the license.

**Source: The Mount Sinai Hospital / Mount Sinai School of Medicine

Breaching the blood-brain barrier

Cornell University researchers may have solved a 100-year puzzle: How to safely open and close the blood-brain barrier so that therapies to treat Alzheimer's disease, multiple sclerosis and cancers of the central nervous system might effectively be delivered. The researchers found that adenosine, a molecule produced by the body, can modulate the entry of large molecules into the brain. For the first time, the researchers discovered that when adenosine receptors are activated on cells that comprise the blood-brain barrier, a gateway into the blood-brain barrier can be established.
Although the study was done on mice, the researchers have also found adenosine receptors on these same cells in humans. They also discovered that an existing FDA-approved drug called Lexiscan, an adenosine-based drug used in heart imaging in very ill patients, can also briefly open the gateway across the blood-brain barrier.
The blood-brain barrier is composed of the specialized cells that make up the brain's blood vessels. It selectively prevents substances from entering the blood and brain, only allowing such essential molecules as amino acids, oxygen, glucose and water through. The barrier is so restrictive that researchers couldn't find a way to deliver drugs to the brain -- until now.
"The biggest hurdle for every neurological disease is that we are unable to treat these diseases because we cannot deliver drugs into the brain," said Margaret Bynoe, associate professor of immunology at Cornell's College of Veterinary Medicine and senior author of a paper appearing Sept. 14 in the Journal of Neuroscience. Aaron Carman, a former postdoctoral associate in Bynoe's lab, is the paper's lead author. The study was funded by the National Institutes of Health.
"Big pharmaceutical companies have been trying for 100 years to find out how to traverse the blood-brain barrier and still keep patients alive," said Bynoe, who with colleagues have patented the findings and have started a company, Adenios Inc., which will be involved in drug testing and preclinical trials.
Researchers have tried to deliver drugs to the brain by modifying them so they would bind to receptors and "piggyback" onto other molecules to get across the barrier, but so far, this modification process leads to lost drug efficacy, Bynoe said.
"Utilizing adenosine receptors seems to be a more generalized gateway across the barrier," she added. "We are capitalizing on that mechanism to open and close the gateway when we want to."
In the paper, the researchers describe successfully transporting such macromolecules as large dextrans and antibodies into the brain. "We wanted to see the extent to which we could get large molecules in and whether there was a restriction on size," Bynoe said.
The researchers also successfully delivered an anti-beta amyloid antibody across the blood-brain barrier and observed it binding to beta-amyloid plaques that cause Alzheimer's in a transgenic mouse model. Similar work has been initiated for treating multiple sclerosis, where researchers hope to tighten the barrier rather than open it, to prevent destructive immune cells from entering and causing disease.
Although there are many known antagonists (drugs or proteins that specifically block signaling) for adenosine receptors in mice, future work will try to identify such drugs for humans.
The researchers also plan to explore delivering brain cancer drugs and better understand the physiology behind how adenosine receptors modulate the blood-brain barrier.

**Source: Cornell University