domingo, 18 de novembro de 2007

Os animais e a medicina - algumas histórias

Olá pessoal,
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Estou colocando aqui alguns links de hitórias interessantes onde animais foram usados em importantes descobertas médicas. Sim, eles são os verdadeiros herois da medicina! Nós, cientistas, reconhecemos isso
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Amanhã é o debate na TV Senado, e irei me confrontar com uma pessoa que prega o fim do uso de animais na pesquisa - se tais idéais viram lei, pode ser o fim da produção de vacinas, de soros contra picadas de animais peçonhentos, de novos medicamentos, de testes para medicamentos genéricos, etc. Podemos voltar para a Idade Média!
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Insulina e o tratamento da diabetes
Descoberta graças ao uso de cães, nos anos 20, em Toronto, Canadá.
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Na foto (clique na imagem para ampliar) estão Frederick Banting, Charles Best e um dos 10 cães usados nos primeiros experimentos da dupla de canadenses. Estudavam a insulina e procuravam a cura da diabetes - lá nos anos 20. Daquela época para cá, o uso de insulina tem salvo a vida de milhões de vidas humanas (sem falar da vida de animais domésticos com diabetes).
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Vejam o texto abaixo sobre os primeiros usos da insulina:
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On January 11, 1922, Leonard Thompson, a 14-year-old diabetic who lay dying at the Toronto General Hospital, was given the first injection of insulin. However, the extract was so impure that Thompson suffered a severe allergic reaction, and further injections were canceled. Over the next 12 days, Collip worked day and night to improve the ox-pancreas extract, and a second dose injected on the 23rd. This was completely successful, not only in not having obvious side-effects, but in completely eliminating the glycosuria sign of diabetes.
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Children dying from diabetic keto-acidosis were kept in large wards, often with 50 or more patients in a ward, mostly comatose. Grieving family members were often in attendance, awaiting the (until then, inevitable) death. In one of medicine's more dramatic moments Banting, Best and Collip went from bed to bed, injecting an entire ward with the new purified extract. Before they had reached the last dying child, the first few were awakening from their coma, to the joyous exclamations of their families.
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Recomendo ler o material histórico da wikipedia sobre o tema:
http://en.wikipedia.org/wiki/Insulin
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Frederick Banting recebeu o Prêmio Nobel de Medicina de 1923
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Colesterol e a causa da aterosclerosis
Estudos inicias feitos na Rússia com coelhos alimentados com ovos
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Vejam trechos de um artigo publicado no Texas Heart Inst. Journal em 2006
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In 1908, Nikolai N. Anichkov (spelled Anitschkow in the German literature) became interested in the work of Dr. Ignatowski, an associate professor at the Military Medical Academy, whose preliminary work suggested that rabbits might develop atherosclerosis after eating non-vegetarian food, including meat and eggs. Upon his graduation in 1909, Anichkov began to work on his doctoral thesis, titled “Inflammatory changes in myocardium: apropos of myocarditis,” (...). In this work, Anichkov introduced foreign bodies into the myocardium of experimental animals and studied the inflammatory response that occurred during periods from 2 hours to 1 year afterward. In this thesis, Anichkov first described the myocyte that today bears his name. He believed that these “Anitschkow cells” awere a result of the degeneration of myocardial cells that were losing their contractile ability.
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In February 1913, Anichkov arrived in Strasbourg to work in the laboratory of the famous Austrian pathologist Hans Chiari. On 15 April 1915, Anichkov wrote in a letter:
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"Once a year Chiari delivers a course with specimen demonstrations for the military doctors, which he considers of extreme importance. Chiari prepares his lectures for the course far in advance and selects the most interesting specimens. Prior to his last lecture, Chiari asked me to bring the specimen of the aorta of our last rabbit and demonstrate the microscopy to the audience, saying that it was of extreme interest to his colleagues and the entire audience."
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Anichkov was the first to describe the “cholesterinesterphagozyten,” which derive from macrophages and today are known as foam cells. By analyzing atherosclerotic plaque's development and histology, Anichkov identified the cell types involved in the atherosclerotic process: smooth muscle cells, macrophages, and lymphocytes.
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Vale a pena ler toda a história do médico russo Anickov (clicar aqui).
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Veja outros materiais sobre a história da aterosclerose
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jn.nutrition.org/cgi/reprint/125/3_Suppl/589S.pdf
(descreve em detalhe os experimentos clássicos - em inglês)
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www.raccv.caccv.org/Vol02N03/etiologiaarteriosclerosis.htm
(texto de divulgação para leigos - em espanhol)
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(talk-show do Ciência Brasil TV sobre colesterol)
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Paul Ehrlich e o tratamento da sífilis
Seus estudos com arsênicos (em animais) deu origem a farmacologia moderna
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Leiam o texto abaixo:
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The origin of syphilis and the first case of syphilis in nearly unknown still to the science. Several guesses have been made about the origin and the most common ones are, that the first case of syphilis happened in Europe in the year of 1493 or 1494. The second popular guess is, that syphilis has followed mankind through out its history, going under different names. But in the 13th century, changes in the sexual behaviour resulted an epidemic in Europe.
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The second school of opinions claims strongly, that there was no syphilis in the old continent, but that the men of Columbus brought the disease from the new world. The main point however stays; that there is no certainty, about the origin of syphilis and it’s still under many controversies.
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In any case syphilis stayed to plague mankind and without a treatment all the way to the early part of the 20th century. A German man named Paul Ehrlich (1908 Nobel Prize in Medicine) had worked through out the early years of 20th century, among anti-bacterial substances. He was looking for a substance that could destroy the harmful bacteria inside the body so, that it would not harm the person itself. The mercury which was used to cure syphilis, caused for patients such a horrific side-effects, that many patients chose to live with the syphilis, rather than try to cure it.
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In 1909 Paul Ehrlich had already tested [in laboratory animals] well over 900 different substance combinations, without a great success. His colleague Sahachiro Hata however decided once more return to work with the substance labeled as 606. While trying the substance number 606 once more, he noticed that it was effective against the microbe of syphilis, which were just recently recognized. Together Ehrlich and Hata tested this substance 606 over and over again with mice, guinea pigs and with rabbits that had been infected with syphilis. They managed to cure the animals in three weeks so, that not a single one of the animals died to the treatment. In 1910 Salvarsan appeared to the markets and it was an instant success all over the world. Salvarsan, or sometimes-just 606, helped also Germany to rise to the top of the pharmaceutical industry and finally made the syphilis a disease that could be cured.
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The substance combination that Paul Ehrlich invented was an effective medicine against syphilis, but it didn’t help to fight against other diseases. However the work done by Ehrlich, laid a foundation for chemotherapy and inspired other researchers, the most famous one of them being most likely Sir Alexander Fleming.
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2 comentários:

Anônimo disse...

Desde Anitschkow em 1908, e principalmente nos últimos 50 anos, a ciência médica continua insistindo em colocar o colesterol como o grande vilão e a causa da aterosclerose, apesar da pouca base científica para isso. Veja o artigo "A farsa do colesterol alto" com a tradução da entrevista recente de Sandrine Blanchard com o famoso cardiologista françês Michel de Lorgeril publicada originalmente no Jornal Le Monde.

Veja também na mesmo página da web sobre uma nova teoria brasileira que revoluciona o conhecimento sobre a doença coronariana, colocando o estresse como o maior precursor no desenvolvimento da aterosclerose!, em http://brasil.indymedia.org/pt/blue/2007/09/394088.shtml

Anônimo disse...

Parabéns pelos post sobre animais! Embora para alguns pareçam crueis as pesquisas com animais, eleas mais beneficiam do que causam sofrimento, e isso vale para os próprios animais! A história da insulina é realmente impressionante..