Pesquisa revisa 12 mil casos de câncer para definir melhores formas de tratamento

Saber sobre o câncer

O uso de quimioterápicos orais não substitui com a mesma eficácia a quimioterapia endovenosa em pacientes com câncer de intestino.

Uma quimioterapia de curta duração em pacientes com câncer de pulmão apresenta os mesmo resultados que uma quimioterapia de longo prazo.

Pacientes com câncer de rim sem metástases têm melhores resultados clínicos se tratados apenas com cirurgia do que inicialmente com cirurgia e, depois, com quimioterapia, hormonioterapia ou imunoterapia.

Essas são algumas das conclusões de um estudo que revisou cerca de 12 mil casos de pacientes com diversos tipos de câncer publicados na literatura internacional.

O trabalho foi realizado no Centro de Evidência em Oncologia (Cevon) do Hospital de Clínicas (HC) da Universidade Estadual de Campinas (Unicamp).

Medicina baseada em evidências

Criado em 2007 a partir da contratação do médico oncologista André Deeke Sasse para ensinar aos médicos residentes a metodologia da medicina baseada em evidências (MBE), o objetivo principal do Cevon é oferecer aos pacientes com câncer atendidos no ambulatório de oncologia do HC da Unicamp um cuidado mais atual e eficaz por meio da utilização das melhores evidências científicas para o tratamento do câncer.

A MBE (medicina baseada em evidências) é um movimento médico criado em 1972 pelo professor e pesquisador britânico Archie Cochrane.

A MBE se fundamenta na aplicação do método científico a toda prática médica, usando técnicas oriundas da ciência, engenharia e estatística, tais como metarrevisões da literatura existente - denominadas também de meta-análises -, análise de custo-efetividade, experimentos clínicos aleatórios e controlados, estudos naturalísticos populacionais, dentre outros.

A prática da MBE implica não somente no conhecimento e na experiência clínica, mas também em procurar, encontrar, interpretar e aplicar os resultados de estudos científicos epidemiológicos ao problema individual dos pacientes.

Implica, também, em conhecer como calcular e comunicar os riscos e os benefícios dos diferentes tratamentos existentes na medicina aos pacientes.

Meta análises

Uma meta-análise é desencadeada a partir de uma pergunta clínica.

Para ser bem formulada, ela deve ter quatro componentes e pode ser abreviada com a sigla PICO: P de paciente, população ou problema de interesse; I de intervenção principal, que pode ser uma exposição (agente etiológico), um teste diagnóstico, um fator prognóstico ou um tratamento; C de comparador, ou seja, a intervenção ou exposição a que se deseja comparar a intervenção principal; e O da palavra inglesa outcomes, ou seja, os desfechos clínicos de interesse, que podem incluir fator temporal, se relevante, como, por exemplo, sobrevida livre de doença em cinco anos.

"A pergunta de nossa última revisão sistemática com meta-análise foi a seguinte: pacientes com câncer de pulmão do tipo pequenas células com o uso de quimioterapia com cisplatina e camptotecinas (uma nova classe de drogas) comparada com o uso padrão da quimioterapia com cisplatina e etoposídeo resultam em uma melhora do tempo de vida total dos pacientes?

"Descobrimos que sim, além de diminuir os efeitos colaterais associados à terapia", explicou Sasse.

Pesquisa sem laboratório

No final de 2010, a convite da Universidade de Oxford e da Associação Médica Britânica, Sasse participou do "Evidence 2010", ocorrido em Londres, e mostrou a experiência brasileira da criação do Cevon. Segundo Sasse, o Cevon é um centro de pesquisa barato que não envolve bancadas, nem laboratórios e nem pesquisas diretas com pacientes. O caso brasileiro despertou interesse da comunidade internacional, em razão do grande número de revisões sistemáticas concluídas em tão pouco tempo.

"O André nos procurou para conduzir estudos de meta-análise desenvolvidos por ele fora da Universidade. Nós não tínhamos ninguém que fizesse isso aqui. Inicialmente, ele começou a ensinar os residentes. Hoje, ele tem vários orientandos de mestrado e doutorado", explicou a médica oncologista Carmen Silvia Passos Lima, responsável pela disciplina de oncologia clínica do Departamento de Clínica Médica da Faculdade de Ciências Médicas (FCM) da Unicamp.

Assédio da indústria farmacêutica

De acordo com a professora, o trabalho do Cevon desperta também a atenção dos médicos para um assunto polêmico e atual: o assédio da indústria farmacêutica no sentido de utilizar novos medicamentos lançados no mercado.

"É fundamental que nossos alunos e residentes tenham a visão de que um artigo ou uma informação de um determinado laboratório não devam ser utilizados para mudar a conduta no tratamento dos pacientes, mas sim a somatória de diversos resultados, como o que obtemos por meio da meta-análise. Nós ensinamos isso aos nossos alunos, futuros médicos", explicou Carmen.

Segundo Sasse, dados de pesquisas patrocinadas pela indústria farmacêutica nem sempre aparecem nos artigos científicos. "Este foi um dos temas abordados no congresso. Outro ponto discutido no evento foi o quanto vale para a sociedade e para o paciente ficar vivo às custas de efeitos colaterais e de qualidade de vida deteriorada", comentou Sasse.

Idealista, o médico oncologista espera consolidar o Cevon e ampliar a MBE para o estudo de todos os tipos de câncer, além de auxiliar o desenvolvimento de diretrizes clínicas para outras disciplinas não-oncológicas. Outro objetivo de Sasse é ampliar o curso de medicina baseada em evidências para todos os residentes e para os médicos em geral da Unicamp.

"Queremos expandir essa experiência para outras áreas do HC. Desejo também ajudar a avaliar a incorporação de novas tecnologias em geral em saúde, desde equipamentos novos como máquinas de radiologia e medicina nuclear, até novas drogas para reumatologia e infectologia, criando, talvez, um núcleo de avaliação permanente dentro do HC", disse Sasse.

Mas o que mais o preocupa é a fixação dos profissionais dentro do centro, uma vez que após o término da residência ou pós-graduação, os alunos seguem outros caminhos dentro da carreira médica. "É gratificante saber que somos capazes de fazer trabalhos de qualidade internacional do mesmo nível que o pessoal da Universidade de Oxford. Temos aqui uma agilidade que eles não têm lá fora", concluiu Sasse.

Revisões sistemáticas sobre câncer

De 2008 a 2010, o Cevon completou nove revisões sistemáticas e dois estudos de custo-efetividade que foram apresentados em congressos internacionais e também submetidos à publicação em revistas médicas.

Veja abaixo um resumo dos resultados principais desses trabalhos.

Quimioimunoterapia versus quimioterapia no tratamento do melanoma maligno metastático

Aglutinou resultados de 19 estudos aleatórios sobre o tema com mais de 2,5 mil pacientes.

Demonstrou que a utilização de quimioimunoterapia - associação de imunoterapia com quimioterapia - não traz nenhum tipo de benefício aos pacientes, em comparação à quimioterapia convencional.

Pacientes não necessitam ser tratados com esquemas altamente tóxicos e com grande perda de qualidade de vida.

Combinação de bevacizumabe à quimioterapia no tratamento de pacientes com câncer de cólon

Associou resultados de cinco estudos com mais de 3 mil pacientes. Demonstrou que a nova droga de alto custo bavecizumabe pode melhorar os resultados do tipo de quimioterapia usada em pacientes com tumores intestinais.

Porém, segundo o estudo, nem todo quimioterápico terá sua eficácia aumentada.

Isso diminui a indicação da nova droga e o número de pacientes que sofrerá seus efeitos colaterais, mantendo a máxima eficácia da estratégia de tratamento.

Camptotecinas comparadas ao etoposídeo, na combinação à cisplatina, no tratamento de câncer de pulmão

O trabalho incluiu dados de oito estudos e mais de 3 mil pacientes.

Demonstrou que a utilização de quimioterapia mais moderna (irinotecano) em comparação a mais antiga (etoposídeo) aumenta um pouco o tempo de vida e a chance de controle da doença em pacientes com um tipo de câncer de pulmão (pequenas células), mas, principalmente, diminui os efeitos colaterais associados à terapia.

Duração do tratamento quimioterápico para pacientes com câncer de pulmão com metástases à distância

Combinou resultados de sete pesquisas independentes com mais de 1,5 mil pacientes estudados.

Demonstrou que um tratamento com curta duração (cerca de três meses) apresenta igual eficácia à de um tratamento mais longo, de seis meses ou mais.

Possibilita aos pacientes ficarem mais tempo sem os efeitos colaterais do tratamento. O estudo foi publicado na revista European Journal of Cancer.

Utilização de radioterapia após quimioterapia em pacientes com linfoma

Com avaliação de dados de quatro estudos e quase 2 mil pacientes, o estudo concluiu que ainda faltam dados confiáveis a respeito do potencial benefício que o tratamento com radioterapia pode adicionar aos pacientes já tratados com quimioterapia.

A maioria dos pacientes com linfoma, hoje, é tratada inicialmente com quimioterapia e depois recebe radioterapia para complementar o tratamento.

Os resultados do estudo sugerem que talvez a radioterapia não necessite ser feita, o que diminuiria drasticamente os riscos do tratamento e seus efeitos colaterais.

Terapia adjuvante à cirurgia para pacientes com câncer renal localizado

Combinando dados de mais de 2,5 mil pacientes avaliados em 10 estudos clínicos diferentes, o estudo demonstrou que pacientes com câncer de rim e sem metástases têm melhores resultados clínicos se tratados apenas com cirurgia do que se tratados inicialmente com cirurgia e depois com outras terapias (como quimioterapia, hormonioterapia ou imunoterapia).

O estudo contribuiu para evitar a indicação de tratamentos desnecessários e que potencialmente poderiam prejudicar pacientes.

Combinação de cetuximabe à quimioterapia no tratamento de pacientes com câncer de cólon

Associou resultados de seis estudos, com mais de 4 mil pacientes.

Demonstrou que a nova droga cetuximabe, de alto custo, pode melhorar os resultados da quimioterapia endovenosa em pacientes com tumores intestinais com um certo tipo de mutação genética.

Pacientes usando parte da quimioterapia por meio de comprimidos não foram beneficiados com essa associação. Isso diminui a utilização da nova droga e seleciona melhor os pacientes que podem se beneficiar da medicação.

Fluoropirimidinas orais versus fluorouracil no tratamento de pacientes com câncer colorretal

Contou com avaliação de dados de quase 12 mil pacientes de 21 estudos clínicos diferentes.

Concluiu que em pacientes com câncer de intestino o uso de quimioterápicos orais não substitui de forma igual a quimioterapia endovenosa, pois apresenta eficácia um pouco menor.

Os quimioterápicos com o nome de fluoropirimidinas (capecitabina e UFT, os mais comuns) são frequentemente usados como substitutos do fluorouracil, uma droga endovenosa geralmente utilizada em infusão lenta, de 48 horas. Apesar de mais práticos, os comprimidos são mais caros.

Imaginava-se que tivessem a mesma eficácia. O estudo provou o contrário.

Manual traz indicadores judiciais sobre medicamentos

Estudo gera indicadores que podem servir de base para que o SUS e o sistema de justiça garanta maior acesso da população

A Escola Nacional de Saúde Pública (Ensp/Fiocruz) acaba de disponibilizar o Manual de Indicadores de Avaliação e Monitoramento das Demandas Judiciais de Medicamentos. A publicação é resultado de um projeto que estabeleceu 30 indicadores considerados essenciais para se compreender melhor a demanda de medicamentos por meio da Justiça. O trabalho, que teve o Estado do Rio de Janeiro como modelo, gerou indicadores que poderão servir de base para que o SUS e o sistema de justiça possam realizar o monitoramento das ações judiciais e garantir o acesso da população a medicamentos de qualidade e com segurança. O manual está disponível para download na Biblioteca Multimídia da Ensp.

Após a última etapa do projeto seguiu-se um consenso de especialistas, no qual foram validados e selecionados indicadores essenciais para se compreender melhor a demanda judicial de medicamentos 

O objetivo principal não é apenas identificar as dificuldades, mas também criar condições para ação de gestores e profissionais da saúde e do direito, favorecendo a formulação de estratégias, instrumentos e mecanismos para a melhoria da assistência farmacêutica e para a redução da intensidade das ações judiciais. A proposta de metodologia de avaliação e monitoramento das demandas judiciais individuais de medicamentos no Brasil foi desenvolvida no âmbito do projeto Judicialização e saúde pública: proposta de análise e monitoramento das demandas judiciais individuais para o acesso a medicamentos, financiado pelo CNPq.

Segundo Miriam Ventura, coordenadora-adjunta do projeto, uma das diretrizes do Conselho Nacional de Justiça é monitorar as demandas judiciais de saúde com um grupo de trabalho específico, tendo por finalidade pensar ações de gestão para a melhoria da resposta do judiciário às demandas desta natureza. "As demandas de medicamentos têm sido identificadas como algumas das mais intensas", apontou ela. 

Para desenvolver o manual, o grupo de trabalho identificou, inicialmente, 40 indicadores, que foram apresentados e discutidos com especialistas de diversas áreas e diferentes campos de atuação. "Na última etapa do projeto, após a realização de um seminário na Escola de Magistratura do Estado do Rio de Janeiro (Emerj), seguiu-se um consenso de especialistas, reunindo gestores e pesquisadores de variadas instituições e regiões do país, no qual foram validados e selecionados indicadores considerados essenciais para se compreender melhor a demanda judicial de medicamentos. O trabalho, que teve o Estado do Rio de Janeiro como modelo, gerou indicadores que poderão servir de base para que o SUS e o sistema de justiça possam realizar o monitoramento das ações judiciais e garantir o acesso da população a medicamentos de qualidade e com segurança", esclareceu Vera.

Segundo ela, "apesar de o projeto desenvolvido ter como foco este tipo de demanda, os indicadores formulados podem ser aplicados a outras demandas, com pequenas adequações, que já estão sendo desenvolvidas pelo grupo. Nesse sentido, no desenvolvimento do projeto de indicadores de monitoramento, foram analisadas as bases de dados do Tribunal de Justiça e da Secretaria de Saúde e Defesa Civil do Estado do Rio de Janeiro com o objetivo de identificar possíveis indicadores de avaliação e monitoramento das demandas judiciais de medicamentos". 

Para o desenvolvimento do material foi realizada também uma extensa análise da literatura existente da área para identificar os estudos já realizados no país. "A revisão desses trabalhos constatou que é muito difícil fazer uma análise comparativa dos estudos brasileiros sobre o tema da judicialização da saúde, pois as variáveis analisadas e perspectivas adotadas são muito diversas", explicou a farmacêutica Cláudia Osório, pesquisadora do Núcleo de Assistência Farmacêutica da Ensp.

O projeto concluiu que o processo de judicialização pode ser analisado e monitorado adotando-se 30 indicadores, divididos em 4 dimensões diferenciadas: indicadores relacionados às características sociodemográficas do autor da ação judicial, que analisam as características da população em relação aos aspectos sociais e demográficos; indicadores relacionados às características político-administrativas das ações judiciais, voltados para os aspectos relacionados às competências executivas, administrativas e econômicas da administração pública; indicadores relacionados às características processuais das ações judiciais, abordando os aspectos que se encontram em conformidade com as leis locais e nacionais; e indicadores relacionados às características médico-sanitárias das ações judiciais, trazendo as características das ações e os aspectos relativos ao corpo de conhecimentos das ciências da saúde. 

Vera Pepe lembrou que, desde 2007, o grupo de pesquisa trabalha em diversos projetos relacionados à judicialização do acesso aos medicamentos no Brasil, sobretudo no Rio de Janeiro. Neles, está incluída a participação de alunos de pós-graduação da Ensp, resultando em monografias, dissertações de mestrado, artigos publicados em periódicos científicos e ampla parceria com instituições gestoras, como a Secretaria de Estado de Saúde e Defesa Civil do Rio de Janeiro, e instituições de pesquisa e ensino do campo da saúde e do direito, como a Escola de Magistratura do Estado do Rio de Janeiro.

'Semana da saúde' no Senado tem 47 projetos em pauta

Prevenção ao uso de drogas, a relação dos clientes com os planos de atendimento e o custeio do setor são temas prioritários

Um total de 47 projetos deve fazer parte da "semana da saúde", esforço concentrado para votação de projetos da área definido pelo presidente do Senado, José Sarney, em conjunto com lideranças partidárias. A prevenção ao uso de drogas, a relação dos clientes com os planos de atendimento e o custeio e a organização da saúde são temas dominantes nas propostas. As informações são da Agência Senado.

A maioria dos projetos tramita nas comissões permanentes do Senado, o que facilita o cumprimento do objetivo, já que a pauta do Plenário está obstruída pelo Projeto de Lei de Conversão 8/11, resultante da Medida Provisória 512/10, com incentivos à indústria automobilística.

A única proposta sobre saúde até agora incluída na ordem do dia do Plenário foi o Projeto de Lei da Câmara (PLC) 194/08, que permite às farmácias e drogarias a manutenção de serviços de aferição da pressão arterial. A votação só deve acontecer após a deliberação sobre o projeto de conversão, prevista para quarta-feira (27).

Drogas

Levantamento da Secretaria-Geral da Mesa do Senado identifica nove propostas no campo da prevenção ao uso de entorpecentes. Uma delas, na pauta da Comissão de Educação, Cultura e Esporte (CE), é o PLC 49/07, que torna obrigatória, no início de cada sessão de cinema, a exibição de filme publicitário sobre consequências do uso de drogas. 

Com propósito semelhante, o Projeto de Lei do Senado (PLS) 183/10, de autoria do senador Magno Malta (PR-ES), determina que as emissoras públicas de radiodifusão veiculem programas e eventos de artes marciais como instrumento de combate às drogas. O projeto está na Comissão de Assuntos Sociais (CAS).

O uso de cigarros e assemelhados em bares e ambientes fechados é alvo de proibição prevista em três projetos - os PLS 420/05, de Magno Malta; 315/08, de Tião Viana (hoje governador do Acre); e 316/08, de Romero Jucá (PMDB-RR) - em tramitação na Comissão de Desenvolvimento Regional e Turismo (CDR). O PLS 99/11, de Acir Gurgacz (PDT-RO), em exame na CAS, proíbe a venda de cigarros e bebidas alcoólicas nas proximidades de escolas.

Planos de saúde

Também está na CAS projeto apresentado em 2007 pela então senadora Patrícia Saboya (CE) - o PLS 598 - que inclui a cobertura da assistência nutricional pelos planos privados de saúde.

Dois projetos em tramitação da Comissão de Constituição, Justiça e Cidadania - o PLS 79/03, de Delcidio Amaral (PT-MS), e 101/05, de Pedro Simon (PMDB-RS) - têm o mesmo objetivo: dar aos pacientes em serviços de saúde o direito de receber informações completas sobre seu estado e de recusar tratamento ou procedimento prescrito.

O PLS 259/09, de Flexa Ribeiro (PSDB-PA), que se encontra na Comissão de Assuntos Econômicos (CAE), permite a participação de empresa de capital estrangeiro na assistência à saúde. 

Já o PLC 30/09, que aguarda inclusão na ordem do dia do Plenário, desobriga as entidades filantrópicas da área de saúde de constituírem pessoa jurídica independente para operar plano privado de assistência à saúde.

Custeio

A fixação dos montantes mínimos de recursos a serem aplicados pelas três esferas da federação em ações e serviços públicos de saúde é o objetivo de dois projetos: o PLC 89/07 e o PLS 156/07 - complementar. Ambos em tramitação na CAE, objetivam regulamentar o artigo 198 da Constituição, o que é considerado fundamental para a consolidação do Sistema Único de Saúde (SUS). 

Outra proposta, de autoria da Comissão de Serviços de Infraestrutura do Senado (CI) e em exame na CAE - o PLS 98/10 -, permite que recursos do Fundo Nacional de Saúde sejam alocados a projetos de saneamento básico. 

Saúde infantil

A saúde das crianças e adolescentes é alvo de várias propostas, como o PLC 93/10, atualmente na CAS, que prevê a substituição de alimentos não saudáveis na merenda das escolas públicas e privadas. 

O PLS 196/07, de autoria de Jayme Campos (DEM-MT) e em exame na Comissão de Meio Ambiente, Defesa do Consumidor e Fiscalização e Controle (CMA), determina que os rótulos de bebidas especifiquem o teor calórico e apresentem frases de advertência sobre os riscos da obesidade infantil.

O levantamento da Secretaria-Geral da Mesa do Senado identifica ainda 17 matérias indiretamente relacionadas com a saúde, como o PLS 159/10, do senador Gim Argello (PTB-DF), em exame terminativo na CAS, que proíbe a comercialização de mamadeiras, bicos e chupetas que contenham bisfenol-A. Também conhecido como BPA, o bisfenol-A foi proibido em diversos países após as suspeitas de que é prejudicial à saúde.

New Drug Target Discovered for Kidney Disease

ScienceDaily (Apr. 26, 2011) — Two discoveries at UC Santa Barbara point to potential new drug therapies for patients with kidney disease. The findings are published in this week's issue of theProceedings of the National Academy of Sciences.

Mouse polycystic kidney 

Over 600,000 people in the U.S., and 12 million worldwide, are affected by the inherited kidney disease known as autosomal-dominant polycystic kidney disease, or ADPKD. The disease is characterized by the proliferation of cysts that eventually debilitate the kidneys, causing kidney failure in half of all patients by the time they reach age 50.

Currently, no treatment exists to prevent or slow cyst formation, and most ADPKD patients require kidney transplants or lifelong dialysis for survival, explained Thomas Weimbs, director of the laboratory where the discoveries were made. Weimbs is an associate professor in the Department of Molecular, Cellular and Developmental Biology and the Neuroscience Research Institute at UCSB.

First, Weimbs and his research team discovered a molecular mechanism that sheds light on the disease. The mechanism concerns polycystin-1, a protein that is mutated in ADPKD patients. The team discovered how this protein regulates a well-known transcription factor called STAT3. Transcription factors transcribe information from DNA to RNA, from specific genes. Second, the team discovered that STAT3 is strongly, and aberrantly, activated in polycystic kidneys.

"The clinical significance of these discoveries lies in the fact that STAT3 is also known to be aberrantly activated in many forms of cancer and is considered an important drug target for cancer therapy," said Weimbs. "Numerous STAT3 inhibitors are currently being developed and tested, and several experimental drugs are already available. Our results suggest that STAT3 activation is a driving force for the cyst growth that leads to polycystic kidneys in ADPKD. Therefore, STAT3 may be a highly promising drug target for the treatment of ADPKD."

Weimbs explained further that STAT3 is a signaling molecule that is activated in response to many different growth factors binding to specific receptors on the surface of kidney cells. In response to these growth factors hitting the cell, STAT3 is activated. That causes STAT3 to turn on the expression of certain genes. This activity causes the cells to proliferate, as they do in cancer.

"In polycystic kidney disease, we have strong proliferation, but it is similar to having benign tumors -- where the tumor stays in place," said Weimbs. "The cysts keep growing, but they do not metastasize or invade other tissues as do cancerous tumors. Polycystic kidneys are full of small, benign tumors or cysts. This is still very destructive, because eventually the disease will destroy the kidney."

The research team is currently testing STAT3 as a drug target in mice with ADPKD.

The National Institutes of Health funded the research.

Structural Biologists Reveal Molecular Architecture of Key NMDA Receptor Subunit

ScienceDaily (Apr. 26, 2011) — Structural biologists at Cold Spring Harbor Laboratory (CSHL) in collaboration with colleagues at Emory University have determined the molecular structure of a key portion, or subunit, of a receptor type commonly expressed in brain cells. The receptor is one of several NMDA (N-methyl-D-aspartate) receptor variants, and the subunit in question is that which specifically binds with excitatory neurotransmitters, most notably glutamate, the brain's most prevalent excitatory neurotransmitter.

X-ray crystallography data enabled the team to render the precise conformation of the GluN2D subunit when docked with different neurotransmitters. This shows one view of the docking with L-glutamate, which is associated with slow neuronal deactivation time. 

The discovery is important because knowledge of the receptor subunit's precise physical shape and biochemical characteristics can now form a basis upon which to design new drugs that will interact with the receptor, whose dysfunction is known to be implicated in depression, schizophrenia, Parkinson's and Alzheimer's diseases as well as stroke-related brain injuries.

The release and reception of neurotransmitters at synaptic junctions that form between nerve cells mediates a majority of communication between these cells. NMDA receptors are comparatively large multi-unit proteins found at the membrane of a particular class of nerve cells. "The way in which neurotransmitter molecules bind to a receptor determines the strength of neuronal activities," explains CSHL Associate Professor Hiro Furukawa, who led the effort to obtain and "solve" the structure of an NMDA receptor subunit called GluN2D.

Somewhat like a child's building-block puzzle, NMDA receptors are assembled out of combinations of two types of subunits, called GluN1s and GluN2s. While two "blocks" of each are present in every complete NMDA receptor, Furukawa and colleagues focused on solving the structure of one of four possible variants of the GluN2 subunit, which are designated with the letters "A" through "D."

"An NMDA receptor displays different characteristics, depending on which of the four GluN2 subunits it contains," explains Furukawa. "What's especially interesting about the GluN2D subunit is that its presence means the receptor will take about 40 times longer to deactivate after being stimulated, as compared with a receptor containing the GluN2A subunit. We and others in the field think this unique property is important for early brain development as well as in the normal function of neurons expressing receptors with this subunit in the mature brain."

Using x-ray crystallography -- a method that features exposing a crystal of the molecule under study to very high-energy x-ray beams, which reveals its features -- the team was able to visualize a unique conformation of the GluN2D subunit that is suited to mediate "slow" neuronal deactivation. The team's data, published online April 26 in Nature Communications, revealed that a glutamate variant called L-glutamate, when docked with the GluN2D receptor subunit, elicits a much slower deactivation of the receptor as compared with other excitatory neurotransmitter molecules.

"We were able to show a unique structural conformation in that pairing that is coincident with the slower deactivation time," Furukawa says. This gives the team a basis for understanding why deactivation time is so dramatically different depending on which of the GluN2 subunits is involved in linking up with the excitatory neurotransmitter molecule.

Surprisingly, this conformation was observed only when GluN2D was bound to glutamate, but not other known excitatory neurotransmitters, such as aspartate. "It is as if glutamate were acting as a special neurotransmitter expressly designed to mediate a slow response when acting on GluN2D subunits," says Furukawa. "This stunning aspect of GluN2D function is extremely important for the field of neuropharmacology because it now predicts that GluN2D may not be as slowly de-activating as previously expected in neurons where aspartate is used as a primary neurotransmitter."

Studies of Mutated Protein in Lou Gehrig’s Disease Reveal New Paths for Drug Discovery

ScienceDaily (Apr. 26, 2011) — Several genes have been linked to ALS, with one of the most recent called FUS. Two new studies in PLoS Biology, one from the University of Pennsylvania School of Medicine, and the other from colleagues at Brandeis University, both examined FUS biology in yeast and found that defects in RNA biology may be central to how FUS contributes to ALS, or Lou Gehrig's disease. These findings point to new targets for developing drugs.

The top image is of yeast expressing FUS. Note the presence of FUS clumps in the cytoplasm (green foci) and the position of the nucleus (blue). The bottom image is an electron microscopy image of clumps formed by pure FUS in the test tube.

Proteins aggregate to form insoluble clumps in the brain and spinal cord of ALS patients. In some instances of ALS, the clumping protein is FUS, while in other cases it is another protein called TDP-43. FUS and TDP-43 are both RNA-binding proteins with similar features. For example, both proteins contain a region that is remarkably similar to the type of section that enables some proteins to form prions in yeast. Prions are rogue infectious proteins that cause mad cow disease in cattle and Creutzfeldt-Jakob disease in humans. Despite these similarities it was not clear if TDP-43 and FUS both contribute to ALS in similar or different ways.

In 2009, two groups found mutations in the FUS gene in some ALS patients. In the same year, co-senior author Aaron Gitler, PhD, assistant professor of Cell and Developmental Biology, used a yeast model to study FUS and to determine what effect those mutations were having on its function. Meanwhile, co-senior author James Shorter, PhD, assistant professor of Biochemistry and Biophysics, purified the FUS protein and studied the properties that made it readily form clumps. Gitler and Shorter had previously teamed up to study TDP-43 in yeast cells and pure protein assays. "This is an exciting time. The picture is really coming together for the molecular players in ALS." says Gitler.

When the researchers overexpressed human FUS in yeast, clumps formed in the cytoplasm of the yeast cells. TDP-43 formed clumps in the yeast cells too. "However, there were important differences in the way in which FUS and TDP-43 clumped in yeast cells, and pure protein assays," explained Gitler lab postdoctoral fellow and co-first author Zhihui Sun, PhD.

FUS is typically found in the nucleus of human cells. In some ALS-associated mutations of FUS, the protein is more abundant in the cytoplasm, suggesting that it is this misplacement that may be causing disease. In line with that, both groups found that restricting overexpressed normal FUS protein to the nucleus decreased clumping. Both groups showed that the biochemical features that promote clumping differ between FUS and TDP-43.

"The prion-like portion is very important for both proteins to clump, but surprisingly and in contrast to TDP-43, FUS needed additional sequences in a separate part of the protein to initiate clumping," says Shorter. "This suggests that the disease-causing mechanism probably differs between ALS associated with FUS clumping versus TDP-43 clumping," explained Shorter lab research specialist and co-first author Zamia Diaz.

"To be honest, we expected the same behavior for TDP-43 and FUS in yeast and at the pure protein level in terms of how the protein clumps. So, next we asked what proteins reverse the toxicity? Do TDP-43 reversers affect FUS clumping toxicity?" says Gitler.

"We were stunned that they were not the same," notes Shorter.

In the FUS screen they found that genes related to cellular structures called stress granules could rescue FUS-related toxicity in yeast cells. These granules sequester RNAs during times of stress for the cell -- such as increases in temperature, exposure to toxins, or injury -- to use later after stress passes, since cells need to reserve energy. The RNAs are used in the translation of the genetic code into proteins, which uses much of the cell's energy. Mutations in FUS seem to promote it being sequestered in stress granules, and FUS toxicity is associated with these granules. Whether or not these structures played a direct role in FUS toxicity remained unclear. But the new research from both groups suggests that they do play a key role in FUS toxicity. They used genome-wide screens to find genes that could reverse FUS toxicity.

"We were surprised in the genome-wide screens by the lack of overlap in genes that modified FUS toxicity versus TDP-43 toxicity in yeast cells," says Shorter.

"The implication is that we need to target different pathways, that is proteins in FUS-related ALS versus TDP-43-related ALS," adds Diaz.

These studies point the way to new therapeutics for some ALS cases, based on RNA processing. They also suggest caution in the assumption that TDP-43 and FUS both contribute to ALS in the same way. Testing ideas about pathogenesis and treatment is faster and cheaper in yeast, which leads to more rapid progress in understanding the disease and, eventually, its treatment.

"It's truly amazing what we can learn from yeast," concludes Gitler.

Other co-authors on the study are Xiaodong Fang, Michael Hart, Maria Armakola, and Alessandra Chesi, all from Penn.

This study was funded by the National Institutes of Health Director's New Innovator Awards and the National Institute of Neurological Disorders and Stroke, the Robert Packard Center for ALS Research, the Pew Charitable Trusts, and The Ellison Medical Foundation.

Scientists Create Stable, Self-Renewing Neural Stem Cells

ScienceDaily (Apr. 26, 2011) — In a paper published in the April 25 early online edition of theProceedings of the National Academy of Sciences,researchers at the University of California, San Diego School of Medicine, the Gladstone Institutes in San Francisco and colleagues report a game-changing advance in stem cell science: the creation of long-term, self-renewing, primitive neural precursor cells from human embryonic stem cells (hESCs) that can be directed to become many types of neuron without increased risk of tumor formation.

Depicts cultured, self-renewing primitive neural precursors derived from human embryonic stem cells using molecule inhibitors.

"It's a big step forward," said Kang Zhang, MD, PhD, professor of ophthalmology and human genetics at Shiley Eye Center and director of the Institute for Genomic Medicine, both at UC San Diego. "It means we can generate stable, renewable neural stem cells or downstream products quickly, in great quantities and in a clinical grade -- millions in less than a week -- that can be used for clinical trials and, eventually, for clinical treatments. Until now, that has not been possible."

Human embryonic stem cells hold great promise in regenerative medicine due to their ability to become any kind of cell needed to repair and restore damaged tissues. But the potential of hESCs has been constrained by a number of practical problems, not least among them the difficulty of growing sufficient quantities of stable, usable cells and the risk that some of these cells might form tumors.

To produce the neural stem cells, Zhang, with co-senior author Sheng Ding, PhD, a former professor of chemistry at The Scripps Research Institute and now at the Gladstone Institutes, and colleagues added small molecules in a chemically defined culture condition that induces hESCs to become primitive neural precursor cells, but then halts the further differentiation process.

"And because it doesn't use any gene transfer technologies or exogenous cell products, there's minimal risk of introducing mutations or outside contamination," Zhang said. Assays of these neural precursor cells found no evidence of tumor formation when introduced into laboratory mice.

By adding other chemicals, the scientists are able to then direct the precursor cells to differentiate into different types of mature neurons, "which means you can explore potential clinical applications for a wide range of neurodegenerative diseases," said Zhang. "You can generate neurons for specific conditions like amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), Parkinson's disease or, in the case of my particular research area, eye-specific neurons that are lost in macular degeneration, retinitis pigmentosa or glaucoma."

The new process promises to have broad applications in stem cell research. The same method can be used to push induce pluripotent stem cells (stem cells artificially derived from adult, differentiated mature cells) to become neural stem cells, Zhang said. "And in principle, by altering the combination of small molecules, you may be able to create other types of stem cells capable of becoming heart, pancreas, or muscle cells, to name a few."

The next step, according to Zhang, is to use these stem cells to treat different types of neurodegenerative diseases, such as macular degeneration or glaucoma in animal models.

Funding for this research came, in part, from grants from National Institutes of Health Director's Transformative R01 Program, the National Institute of Child Health and Development, the National Heart, Lung, and Blood Institute, the National Eye Institute, the National Institute of Mental Health, the California Institute for Regenerative Medicine, a VA Merit Award, the Macula Vision Research Foundation, Research to Prevent Blindness, a Burroughs Wellcome Fund Clinical Scientist Award in Translational Research and the Richard and Carol Hertzberg Fund.

Co-authors of the study include Wenlin Li, Yu Zhang, Wanguo Wei, Rajesh Ambasudhan, Tongxiang Lin, Janghwan Kim, Department of Chemistry, The Scripps Research Institute; Woong Sun, Xiaolei Wang, UCSD Institute for Genomic Medicine and Shiley Eye Center, Department of Anatomy, Korea University College of Medicine, Seoul, Korea; Peng Xia, Maria Talantova, Stuart A. Lipton, Del E. Webb Center for Neuroscience, Aging and Stem Cell Research, Sanford-Burnham Medical Research Institute; Woon Ryoung Kim, Department of Anatomy, Korea University College of Medicine, Seoul, Korea.

Safeguarding Genome Integrity Through Extraordinary DNA Repair

ScienceDaily (Apr. 26, 2011) — DNA is under constant attack, from internal factors like free radicals and external ones like ionizing radiation. About 10 double-strand breaks -- the kind that snap both backbones of the double helix -- occur every time a human cell divides. To prevent not only gene mutations but broken chromosomes and chromosomal abnormalities known to cause cancer, infertility, and other diseases in humans, prompt, precise DNA repair is essential.

Heterochromatin (purple) accounts for a third of the chromatin in both humans and fruit flies. Some heterochromatin forms the telomeres that cap the ends of the chromatids, and much is concentrated near the centromere, where sister chromatids are joined. Accurate repair of double-strand breaks in heterochromatin is challenging, because most of its DNA consists of short, repeated sequences. 

Scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), working with cell lines of the fruit flyDrosophila melanogaster, have discovered an unsuspected and dramatic process by which double-strand breaks in heterochromatin -- one of the two major kinds of chromatin that make up chromosomes, which accounts for a third of the chromatin in both humans and fruit flies -- are repaired in a series of steps. The repair starts where the break occurs, but stalls until the repair site physically moves away from the original heterochromatin region, before continuing to completion.

Unlike euchromatin, where most of an organism's genes reside and where most DNA consists of long, unrepetitive sequences of base pairs, DNA in heterochromatin consists mostly of short repeated sequences that don't code for proteins; indeed, heterochromatin was long regarded as containing mostly "junk" DNA.

Heterochromatin is now known to be anything but junk, playing a crucial role in organizing chromosomes and maintaining their integrity during cell division. It is concentrated near centromeres, where chromatids are in closest contact, which are required to transmit chromosomes from one generation to the next. Maintaining heterochromatin structure is necessary to the normal growth and functions of cells and organisms.

"Heterochromatin poses more of a problem for DNA repair than euchromatin," says Gary Karpen, whose group in Berkeley Lab's Life Sciences Division discovered the new repair mechanism. "It has lots of short sequences -- many of them only about five base-pairs each -- which are repeated millions of times."

"Repair of simple repeated sequences is particularly challenging," says Irene Chiolo, first author of the group's paper reporting the results in the journal Cell. "They can promote chromosome aberrations, with severe consequences for the genome stability of dividing cells" -- abnormalities that are a hallmark of cancer cells and cause birth defects.

Finding the right path

With the stakes so high, how can cells insure fast, accurate repair of double-strand breaks? Two main repair pathways are available. One method, nonhomologous end-joining, simply cleans up the ends of the broken strands and glues them back together regardless of sequence. This might seem a good choice for heterochromatin: it almost always creates small deletions or mutations, but these are in repetitive, noncoding sequences and do not affect genes.

Far more accurate but more complex is homologous recombination, a mechanism involving many steps where something could go wrong. Upon detecting a double-strand break in DNA, several proteins rush to the damaged area. The protein machinery trims back the ends of the broken strands (called 'resection')to produce single-strand regions recognized by other proteins, including one called ATRIP.

Another protein, Rad51, is recruited to form filaments on the single-stranded DNA. Rad51 and its associated proteins search for a complementary sequence of DNA in a neighboring chromatid or homologous chromosome. They invade and open that DNA to form a "D-loop" -- like untwisting a rope to open and expose its individual strands. Using the exposed complementary sequence as a template, proteins rebuild the broken DNA into a copy of the sequence that was originally damaged; in this way the broken double strand is remade with its damaged section accurately reproduced.

It's an ideal method for repairing breaks in gene-rich euchromatin. In repetitive heterochromatin, however, danger arises because completely different chromosomes lying close to the site of the break may have great lengths of repeated short sequences that look identical to the region around the break itself. What starts as a repair process may end up splicing different chromosomes together, a common abnormality in cancer cells.

For heterochromatin to employ such a potentially risky repair process seemed counterintuitive. In earlier experiments looking for key signs of repair in mouse heterochromatin after irradiation, classic markers of double-strand break repair by either nonhomologous end-joining or homologous recombination were both absent. In fact it seemed possible that, somehow, such breaks didn't occur in heterochromatin.

"There were no signs of repair half an hour after the cells were exposed to ionizing radiation," says Karpen. "But our group looked at Drosophila cells just 10 minutes after radiation exposure. Now the early signs of homologous recombination were clearly evident."

After half an hour, however, these signs too -- signals from modified histones, the component proteins that form the "spools" around which the DNA "thread" is wound in chromatin, as well as signals from ATRIP recruitment -- were missing from the heterochromatin domain. What had become of the repair process?

Now you see it, now you don't

In a series of experiments, Karpen and Chiolo and their colleagues found that in heterochromatin the early stages of homologous recombination -- resection and ATRIP loading -- appear within three minutes after the damage occurs. The next steps in homologous recombination seemed blocked from entering the heterochromatin at this stage. These steps -- the activity of the Rad51 proteins in preparing invasive filaments of single-strand DNA -- are the most dangerous, where mistaken recombination could easily occur.

By 30 minutes after radiation damage was inflicted, the entire domain had swollen and began sending out expanding and contracting 'fingers' of chromatin. Now, after the relocation of the damaged DNA to outside the heterochromatin, the Rad51 proteins did appear; the researchers found them moving with the ends of the heterochromatin 'fingers'. After an hour the whole domain partially contracted again, indicating that the broken DNA had moved to the periphery of the heterochromatin domain in order to load Rad51 protein and complete the repair process.

"There are a lot of moving parts here," says Karpen. "It opens new ways of thinking about DNA repair and investigating the process."

It's common to picture chromosomes as rather floppy tubes of stuff that are tightly cinched in their middles to form X-shaped figures, but in fact this is a condensed state that occurs only briefly during mitosis, when cells divide. Most of the time chromosomes aren't condensed -- instead they exist as somewhat diffuse clouds of DNA.

"In the last 20 years researchers have found that the DNA for each chromosome occupies a separate domain in the nucleus, even when chromosomes are decondensed," says Chiolo. "From these 'chromosomal territories' the DNA moves to accomplish certain functions, for example gene transcription, by going to where the proteins are. We now observe that similar movements occur even during DNA repair."

Says Karpen, "The process we discovered is an extreme version of this dynamism, where the DNA repair process starts in one domain, then the damaged DNA goes elsewhere to complete repair. It would seem that starting repair in one place, then moving elsewhere is risky, and could result in unrepaired damage, which is just as dangerous to the cell as abnormal recombination with a different chromosome."

Says Chiolo, "Stability is the key. The presence of resected DNA ends is extremely dangerous in heterochromatin only if Rad51 is loaded onto broken DNA." Sure enough, the researchers discovered that a protein complex called Smc5/6 blocks Rad51 recruitment until the damaged DNA is moved outside the heterochromatin.

Chiolo says, "This mechanism is crucial for safeguarding the genome by blocking aberrant recombination between different chromosomes, and promoting safe repair from a sister chromatin, or homolog, after the double-strand break has relocated outside the heterochromatin domain."

Homologous recombination is a complex mechanism with multiple steps, but also with many points of regulation to insure accurate recombination at every stage. This could be why this method has been favored during evolution. The machinery that relocalizes the damaged DNA before loading Rad51 might have evolved because the consequences of not having it would be terrible.

Karpen and Chiolo and their colleagues are now at work on the next steps in the research, investigating the many unanswered questions about how this surprisingly dynamic mechanism of DNA repair works and what happens when it fails. Perhaps most important is learning whether the unexpectedly sophisticated approach to homologous recombination inDrosophila heterochromatin is conserved in other organisms, including humans.

Green Environments Essential for Human Health, Research Shows

ScienceDaily (Apr. 26, 2011) — Research shows that a walk in the park is more than just a nice way to spend an afternoon. It's an essential component for good health, according to University of Illinois environment and behavior researcher Frances "Ming" Kuo.

Research confirms that the impacts of parks and green environments on human health extend beyond social and psychological health outcomes to include physical health outcomes. 

"Through the decades, parks advocates, landscape architects, and popular writers have consistently claimed that nature had healing powers," Kuo said. "But until recently, their claims haven't undergone rigorous scientific assessment."

Kuo is also the director of the Landscape and Human Health Laboratory at the U of I and has studied the effect of green space on humans in a number of settings in order to prove or disprove the folklore notions.

"Researchers have studied the effects of nature in many different populations, using many forms of nature," Kuo said. "They've looked at Chicago public housing residents living in high-rises with a tree or two and some grass outside their apartment buildings; college students exposed to slide shows of natural scenes while sitting in a classroom; children with attention deficit disorder playing in a wide range of settings; senior citizens in Tokyo with varying degrees of access to green walkable streets; and middle-class volunteers spending their Saturdays restoring prairie ecosystems, just to name a few."

Kuo says that although the diversity of the research on this subject is impressive and important, even more important is the rigor with which the work was conducted.

"In any field with enthusiasts, you will find a plethora of well-meaning but flimsy studies purporting to 'prove' the benefits of X," Kuo said. "But in the last decade or so, rigorous work on this question has become more of a rule than an exception. The studies aren't simply relying on what research participants report to be the benefits of nature. The benefits have been measured objectively using data such as police crime reports, blood pressure, performance on standardized neurocognitive tests, and physiological measures of immune system functioning."

Kuo said that rather than relying on small, self-selected samples of nature lovers such as park-goers, scientists are increasingly relying on study populations that have no particular relationship to nature. One study examined children who were receiving care from a clinic network targeting low-income populations. Another looked at all United Kingdom residents younger than retirement age listed in national mortality records for the years 2001-2005.

"Scientists are routinely taking into account income and other differences in their studies. So the question is no longer, do people living in greener neighborhoods have better health outcomes? (They do.) Rather, the question has become, do people living in greener neighborhoods have better health outcomes when we take income and other advantages associated with greener neighborhoods into account?" That answer is also, yes, according to Kuo.

After undergoing rigorous scientific scrutiny, Kuo says the benefits of nature still stand.

"We still find these benefits when they are measured objectively, when non-nature lovers are included in our studies, when income and other factors that could explain a nature-health link are taken into account. And the strength, consistency and convergence of the findings are remarkable," she said.

Kuo drew an analogy to animals. "Just as rats and other laboratory animals housed in unfit environments undergo systematic breakdowns in healthy, positive patterns of social functioning, so do people," she said.

"In greener settings, we find that people are more generous and more sociable. We find stronger neighborhood social ties and greater sense of community, more mutual trust and willingness to help others.

"In less green environments, we find higher rates of aggression, violence, violent crime, and property crime -- even after controlling for income and other differences," she said. "We also find more evidence of loneliness and more individuals reporting inadequate social support."

The equation seems too simple to be true.

Access to nature and green environments yields better cognitive functioning, more self-discipline and impulse control, and greater mental health overall.

Less access to nature is linked to exacerbated attention deficit/hyperactivity disorder symptoms, higher rates of anxiety disorders, and higher rates of clinical depression.

If that isn't convincing enough, Kuo says the impacts of parks and green environments on human health extend beyond social and psychological health outcomes to include physical health outcomes.

Greener environments enhance recovery from surgery, enable and support higher levels of physical activity, improve immune system functioning, help diabetics achieve healthier blood glucose levels, and improve functional health status and independent living skills among older adults.

By contrast, environments with less green space are associated with greater rates of childhood obesity; higher rates of 15 out of 24 categories of physician-diagnosed diseases, including cardiovascular diseases; and higher rates of mortality in younger and older adults.

"While it is true that richer people tend to have both greater access to nature and better physical health outcomes, the comparisons here show that even among people of the same socioeconomic status, those who have greater access to nature, have better physical health outcomes. Rarely do the scientific findings on any question align so clearly."

Because of this strong correlation between nature and health, Kuo encourages city planners to design communities with more public green spaces in mind, not as mere amenities to beautify a neighborhood, but as a vital component that will promote healthier, kinder, smarter, more effective, more resilient people.

Parks and Other Green Environments: Essential Components of a Healthy Human was published in a research series for the National Recreation and Park Association.

New Sensor Glove May Help Stroke Patients Recover Mobility

ScienceDaily (Apr. 26, 2011) — People who have strokes are often left with moderate to severe physical impairments. Now, thanks to a glove developed at McGill, stroke patients may be able to recover hand motion by playing video games. The Biomedical Sensor Glove was developed by four final-year McGill Mechanical Engineering undergrads under the supervision of Professor Rosaire Mongrain.

A new sensor glove may help stroke patients recover hand mobility by playing video games. 

It is designed to allow patients to exercise in their own homes with minimal supervision, while at the same time permitting doctors to monitor their progress from a distance, thus cutting down on hospital visits and costs.

Patients can monitor their progress thanks to software, which will generate 3D models and display them on the screen, while at the same time sending the information to the treating physician.

The glove was developed by the students in response to a design request from the startup company Jintronix Inc. The students met with company representatives once a week for several months to develop the glove, which can track the movements of the wrist, the palm and the index finger using several Inertial Measurement Units. Although similar gloves currently exist, they costs approximately $30,000. By using more accurate and less expensive sensors, the students were able to develop a glove that currently costs $1000 to produce.

Jintronix, Inc. has submitted the project to Grand Challenges Canada, which is an independent not-for-profit organization dedicated to improving the health and well-being of people in developing countries, in the hopes that they will receive funding for further development.