sábado, 26 de fevereiro de 2011

CT scans and the risk of cancer - hunt the haunt

A recent article published in Science Magazine has discussed recent concerns that CT scans radiation exposure could lead to cancer. The work of biophysicist David Brenner (Columbia University's Center for Radiological Research Director) has sparked controversy in the field. In a 2001 paper, he tried to weight the risks of radiation exposure in CT scans and found that children that received radiation from a single CT scan had an estimated 1 in 1000 risk of developing a fatal cancer in the future. Although this seems little, given that an average 600,000 abdominal and head CT scans were performed yearly on children by the time of this publication, the predicted number of cancer fatalities possibly linked to CT radiation exposure could reach 500 a year. This conclusion was headlines in all USA and raised angered reactions of many medical physicists and radiologists. One of the main criticisms was that Brenner used Hiroshima bombing data to gauge exposure-risk relation of radiation. However, Brenner said that he used only the data from the bombing survivals that were far enough from the impact point to have received 5-100 millisieverts of radiation, equivalent to 1-2 CT scans. The concerns became stronger after a 2009 report from the National Council on Radiation
Protection and Measurements has issued that, in 2006, CT radiation alone contributed 24% of the U.S. population's radiation
dose. In late 2009, Amy Berrington de González, a radiation epidemiologist at the National Cancer Institute in Bethesda,  published a paper in Archives of Internal Medicine estimating that the approximately 70 million scans performed in the United States in 2007 would lead to about 29,000 new
cancers. There's growing pressure to better regulate CT machines, something FDA is considering. Today, due to loosely regulation and low compliance to existing guidelines, CT scans can deliver a wide range of doses for the same regions with the same machine models. Other problem is the excessive CT scanning, linked to malpractice suits protection and profit interests. A 2010 study in the Journal of the American College of Radiology of 284 outpatient CT scans found that 27% “were not considered appropriate.”

O fortão da turma não precisa ser o mais burro! - Exercício e capacidade intelectual

Um grupo da Pensilvânia, Illinois, Ohio e Texas (EUA) demonstrou, em um artigo publicado no periódico Proceedings of the National Academy of Sciences of the United States of America, que o treinamento aeróbico melhora a memória e aumenta o tamanho do hipocampo em seres humanos. O estudo, um ensaio clínico com 120 pacientes idosos, mostrou que o exercício aeróbico foi capaz de reverter as alterações relacionadas à idade no hipocampo. Além disso, o estudo descobriu que a boa forma física anterior ao ensaio correlacionou-se com menos risco de perda de volume do hipocampo e que a recuperação do hipocampo durante o ensaio associou-se com aumento de BDNF, um marcador de neurogênese. Isso indica que o exercício físico é uma intervenção eficaz para evitar e também tratar estados demenciais próprios da senescência. Outra conclusão é a de que manter a boa forma física ao longo da vida previne a neurodegeneração. Cientistas, corram para a academia!! Como diria o poeta romano Juvenal: mens sana in corpore sano.

sexta-feira, 4 de fevereiro de 2011

Healing with stem cells

The administration of multipotent adult progenitor cells (MAPC) after a spinal cord injury in rodent models prevents shrinkage of neurons, reported a team from Cleveland, Ohio. Inhibition of this process, known as regressive axonal death, reduces inflammation in the region of injury and promotes regeneration of neurons.
This study shows that adult stem cells are able to modify certain aspects of the response after spinal cord injury and also may alter the inflammatory response to mitigate collateral damage in the central nervous system and increase the regenerative capacity of damaged neurons.
MAPC administration significantly decreased the release of a damaging protein called MMP-9 by macrophages. It also induced a change in the macrophages of M1 to M2 and also promoted the growth of sensory neurites beyond the site of injury, inducing their formation. It also allowed the axons to overcome the negative effects of macrophages and inhibitory molecules in their environment, increasing intrinsic growth capacity.
Read the complete report.

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