Pakai Ponsel Berlebihan Picu Kanker Kelenjar Ludah

TEL AVIV -- Sering berbicara di telepon genggam (telepon seluler atau ponsel), bisa membuat mulut seseorang lelah. Namun pengguna telepon genggam yang terlalu berlebihan harus waspada. Bukan karena soal kelelahan mulut. Yang harus diwaspadai adalah radiasi akibat penggunaan ponsel yang berpotensi menyebabkan kanker kelenjar ludah.

Para peneliti di Israel telah melakukan riset dampak buruk penggunaan telepon genggam yang terlalu berlebihan tersebut. Penelitian ini melibatkan sekitar 500 orang Israel yang mengidap kanker. Dalam penelitian ini, data penggunaan telepon genggam para responden dianalisis dan dibandingkan dengan 1.300 pemeriksaan kesehatan. Riset mengenai pengaruh telepon genggam ini kemudian dipublikasikan dalam The American Journal of Epidemiology.

Dari hasil analisis, responden yang biasa memakai telepon dengan menempelkannya di satu sisi kepala selama beberapa jam tercatat 50 persen lebih berisiko mengidap kanker kelenjar ludah. Sebelumnya, penelitian tentang pengaruh telepon genggam memang sudah banyak dilakukan dan kebanyakan selalu memusatkannya pada risiko mengidap penyakit tumor. Beberapa kali, di antara riset tersebut tidak menemukan hubungan signifikan antara radiasi telepon genggam dengan risiko mengidap kanker.

Kanker kelenjar ludah adalah jenis penyakit dengan prevalensi sangat rendah. Inggris misalnya, dari 230 ribu kasus kanker yang ditemukan setiap tahunnya, hanya 550 kasus saja yang berhubungan dengan jenis kanker kelenjar ludah. ''Penggunaan telepon genggam di Israel tercatat lebih tinggi dibanding negara lain di dunia. Fenomena ini memberikan keuntungan bagi riset karena peneliti dapat memantau pengaruhnya untuk jangka panjang atau pun dampak kumulatif yang akan terjadi,'' ujar Dr Siegal Sadetzki yang memimpin riset ini, seperti dilansir BBC, Senin (18/2).

Salah satu temuan kunci dari penelitian ini, kata Sadetzki, adalah penggunaan telepon genggam yang tinggi di wilayah pinggiran atau pedesaan yang berdampak risiko lebih tinggi dibanding di wilayah kota. ''Ada fakta bahwa penggunaan telepon genggam di area dengan sinyal lemah butuh pancaran radiasi yang lebih kuat supaya telepon dapat berfungsi,'' jelasnya.

Namun demikian, Sadetzki menegaskan, satu penelitian saja tidak cukup untuk membuktikan suatu hubungan sehingga penelitian lanjutan perlu dilakukan. Hingga bukti-bukti baru ditemukan, lanjut dia, pendekatan yang bersifat pencegahan tetap merupakan yang terbaik khususnya dikaitkan dengan penggunaan telepon genggam pada anak-anak.

Di sisi lain, meskipun temuan baru dari Israel tersebut menunjukkan adanya dampak buruk yang signifikan. Sebuah penelitian terbesar dan terpanjang tentang telepon genggam lainnya justru tak menemukan adanya peningkatan risiko jenis kanker apapun. Penelitian itu melibatkan 420 ribu orang di Denmark, yang telah menggunakan telepon genggam selama 10 tahun. Dari riset di Denmark itu terungkap fakta bahwa kasus kanker ternyata lebih rendah dari yang diperkirakan. eye

http://republika.co.id/koran_detail.asp?id=324243&kat_id=13

40 Persen Makanan Bayi Terkontaminasi Bakteri

BOGOR -- Para peneliti dari Institut Pertanian Bogor (IPB) menemukan 22,73 persen susu formula (dari 22 sampel) dan 40 persen makanan bayi (dari 15 sampel) telah terkontaminasi bakteri Enterobacter sakazakii. Materi yang dijadikan sampel adalah yang dipasarkan antara bulan April hingga Juni 2006.

Kontaminasi oleh E Sakazakii yang menghasilkan enterotoksin tahan panas dapat menyebabkan enteritis (peradangan saluran pencernaan), sepsis (infeksi peredaran darah), dan meningitis (infeksi pada lapisan urat saraf tulang belakang dan otak). Ini berdasarkan pengujian yang dilakukan pada bayi mencit (tikus percobaan).

Sri Estuningsih, jurubicara tim peneliti, Selasa (19/2) menyebutkan bahwa sampel makanan dan susu formula yang diteliti berasal dari produk lokal. Tim tersebut terdiri dari staf pengajar Fakultas Kedokteran Hewan IPB, yakni Hernomoadi Huminto, I Wayan T Wibawan, dan Rochman Naim.

Menurut Sri Estuningsih, penelitian itu dilakukan melalui dua tahap. Tahap pertama, isolasi dan identifikasi E sakazakii dalam 22 sampel susu formula dan 15 sampel makanan bayi. Pada tahap kedua, menguji 12 isolat E sakazakii dari hasil isolasi dan kemampuannya menghasilkan enteroksin (racun) melalui uji sitolisis (penghancuran sel).

Dari 12 isolat yang diujikan terdapat enam isolat yang menghasilkan enteroksin. Uji selanjutnya adalah menguji isolat tersebut pada kemampuan toksin setelah dipanaskan. ''Terdapat lima dari enam isolat tersebut yang masih memiliki kemampuan sitolisis setelah dipanaskan,'' katanya. Selanjutnya, ditentukan satu kandidat dari isolat tersebut dan menguji enterotoksin serta bakteri vegetatifnya pada bayi mencit berusia enam hari. Bayi mencit diinfeksi melalui rute oral (cekok mulut) menggunakan sonde lambung khusus dan steril.

Setelah tiga hari, kemudian dilakukan pengambilan sampel organ mencit tersebut. Hasil pengujian enteroksin murni dan enteroksin yang dipanaskan dan bakteri mengakibatkan enteritis, sepsis dan meningitis. Pemeriksaan tersebut dilakukan dengan metode hispatologi menggunakan pewarnaan hematoksilin eosin.

Dari hasil pengamatan histopatologis yang diperoleh masih dibutuhkan penelitian senada yang lebih mendalam untuk mendukung hasil penelitian tersebut. Ia menyatakan, amat penting dipahami bahwa susu formula bayi bukanlah produk steril. Sehingga, dalam penggunaannya serta penyimpanannya perlu perhatian khusus untuk menghindari kejadian infeksi karena mengonsumsi produk tersebut.

Sri Estuningsih secara pribadi telah melihat langsung fasilitas salah satu perusahaan makanan dan susu formula dengan omzet terbesar di Indonesia. ''Sebagian besar fasilitas tersebut telah memenuhi standar operasional prosedur perusahaan susu formula bayi, dan saat ini masih terus dilakukan upaya untuk mencegah kontaminasi tersebut,'' katanya. n ant

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http://republika.co.id/koran_detail.asp?id=324244&kat_id=13

Penemuan Vaksin HIV Masih Jauh

LONDON -- Setelah lebih dari duapuluh tahun meneliti, para ilmuwan ternyata tidak semakin dekat untuk menemukan vaksin HIV. ''Ini tantangan besar, sebab untuk mengendalikan HIV dengan imunologi. Komunitas ilmiah harus mengalahkan alam, menghadapi alam, dengan keunggulan empat miliar tahun evolusi. Hal itu ternyata belum bisa dilakukan,'' ujar pakar biologi peraih Hadiah Nobel, Profesor David Baltimore, seperti dilansir BBC.

Baltimore yang juga Presiden Perhimpunan Amerika untuk Kemajuan Sains (AAAS) mengaku kekurangberhasilan tersebut mungkin bisa dipahami. ''Tapi, tidak bisa diterima,'' jelasnya . Saat berbicara dalam pertemuan tahunan AAAS di Boston, Baltimore, ia mengatakan bahwa HIV telah mengembangkan cara untuk melindungi diri dari sistem kekebalan manusia. ''Jadi, kita harus bertindak selangkah lebih jauh daripada alam,'' kilahnya.

Dia mengungkapkan, upaya untuk mengendalikan virus melalui antibodi atau dengan meningkatkan sistem kekebalan tubuh manusia berakhir tanpa hasil. Baltimore juga mengaku kecewa dengan kalangan ilmuwan pengembang vaksin. eye

http://republika.co.id/koran_detail.asp?id=324241&kat_id=359

Autis dan Sistem Kekebalan Tubuh Ibu.

Hasil penelitian dari UC Davis M.I.N.D. Institute and Center for Children's Environmental Health telah menemukan bahwa terdapat keterkaitan antara sistem kekebalan tubuh pada darah seorang ibu dan sel otak anaknya yang menderita autis, yang memiliki kemungkinan untuk mempengaruhi perkembangan otak si bayi. Penemuan ini meningkatkan kemungkinan pemberian kekebalan tubuh dari seorang ibu ketika mengandung merupakan salah satu faktor resiko penyakit autis dan pada saat yang sama, penanganan yang baik sebelum melahirkan dapat mencegah penyakit tersebut pada beberapa anak menurut Judy Van de Water professor rheumatology, allergy dan clinical immunology.

Judy dan timnya memulai penelitian terhadap sampel darah dari 123 orang ibu yang 61 orang diantaranya memiliki anak yang menderita autis. Mereka mengisolasi antibodi IgG dari sampel kemudian memberikan antibodinya kepada jaringan otak bayi menggunakan analisa western blot yang mendeteksi reaktifitas antibodi terhadap protein. Hasilnya mengungkapkan pola reaktifitas yang spesifik terhadap 2 protein pada 7 otak bayi dari 61 contoh dari anak penderita autis.

Judy dan timnya belum terlalu mengerti mengapa IgG merespon protein dari otak bayi dengan sangat baik, namun perkiraan mereka bahwa kemunculan ini diperoleh dari antibodi sang ibu ketika mengandung yang diberikan kepada si bayi dan juga pengaruh dari lingkungan semakin menguatkan munculnya autis.

Karakteristik dari autis - penurunan mental, keterbatasan bahasa, prilaku berulang - biasanya terlihat sangat jelas diawal kehidupan sang anak. Beberapa anak lainnya mulai menderita autis ketika usia 12-24 bulan.

Antibodi IgG bertanggungjawab terhadap sistem kekebalan tubuh untuk jangka panjang dalam merespon infeksi, namun dapat juga berkontribusi terhadap penyakit autoimmune seperti arthritis, multiple sclerosis dan lupus. IgG juga menembus plasenta untuk memberikan sistem kekebalan tubuh kepada fetus dan bayi yang baru lahir. Inilah yang menjadi salah satu alasa Judy meneliti peran IgG sebagai faktor potensial penyebab autis.

Untuk selanjutnya, Judy ingin mengetahui efek dari IgG terhadap wanita ketika mereka mengandung, apakah akan menghasilkan respons yang sama seperti respons terhadap protein pada otak bayi.

Sumber : Science Daily, 12 Februari 2008

New Technique Makes Tissues Transparent

ScienceDaily (Feb. 13, 2008) — If humans had see-through skin like a jellyfish, spotting disease like cancer would be a snap: Just look, and see a tumor form or grow.

But humans, of course, are not remotely diaphanous. "The reason a person is not transparent is that their tissues are highly scattering," sending light waves careening through the tissue instead of straight through, as they would through the tissue of that jellyfish, explains Changhuei Yang of the California Institute of Technology.

This scattering, in addition to rendering all of us opaque, makes the detection of disease a much trickier issue, requiring a host of diagnostic tests and procedures. But not, perhaps, for much longer, thanks to a new optical trick developed by Yang, an assistant professor of electrical engineering and bioengineering, and his colleagues, that counteracts the scattering of light and removes the distortion it creates in images.

It is well known that light scattering in a material is not exactly the random and unpredictable process one might imagine. In fact, scattering is deterministic, which means that the path that a beam of light takes as it traverses a particular slice of tissue and bounces and rebounds off of individual cells, is entirely predictable; if you again bounce light through that same swath of cells, it will scatter in exactly the same way.

The process is even reversible; if the individual photons of light that scattered through the tissue could be collected and sent back through the tissue, they'd bounce back along the same path and converge at the original spot from which they were sent. "The process is similar to the scattering of billiard balls on a pool table. If you can precisely reverse the paths and velocities of the billiard balls, you can cause the billiard balls to reassemble themselves into a rack," Yang explains.

Yang, along with his colleagues at Caltech, École Polytechnique Fédérale de Lausanne in Switzerland, and MIT, exploited this phenomenon to offset the murky nature of our tissues.

Their technique, called turbidity suppression by optical phase conjugation (TSOPC), is surprisingly simple. The scientists used a holographic crystal to record the scattered light pattern emerging from a 0.46-mm-thick piece of chicken breast. They then holographically played the pattern back through the tissue section to recover the original light beam. "This is similar to grabbing hold of the direction of time flow and turning it around; the time-reversed photons must retrace their trajectories through the tissue," Yang says. "The task is formidable though, as this is comparable to starting with a rack of 10 to the 18th power billiard balls (or photons), scattering them around the table, and attempting to reassemble them into a rack."

"Until we did this study, it wasn't clear that the effect will be observable with biological tissues. We were pleasantly surprised that the effect was readily observable and remarkably robust," Yang says. "This study opens up numerous possibilities in the use of optical time reversal in biomedicine."

One possible use of the technique is in photodynamic therapy, in which a highly focused beam of light is aimed at cancerous cells that have absorbed cell-killing light-sensitive compounds. When the light hits the cells, the compounds are activated and destroy the cells. Photodynamic therapy is most effective in treating cancers on the skin surface. Yang's technique, however, offers a way to concentrate light onto cancer-killing compounds located more deeply within tissue.

Yang's idea is to inject strongly light-scattering particles that are coated with light-activated cancer-killing drugs into diseased tissue. Shine a beam of light into the tissue, and it would be reflected off the scattering compounds as it bounces through the tissue. Some of the scattered light would return to the source, where it could be recorded as a hologram.

This hologram would contain information about the path that the scattered light took through the tissue, and, in effect, describe the optimal path BACK toward the light-scattering molecule--and the cancer-killing compounds. Playing back the signal with a stronger burst of light will then activate the therapeutic drugs, which kill the cancer cells.

In addition, the technique could offer a way to power miniature implants buried deep within tissues. "If you take a quick survey of what is out there at present, you will see that implants are fairly large," Yang says. "For example, a pacemaker is about the size of a cell phone. Why are they so big? A large part of the reason is because they need to carry their own power sources."

The key to making smaller implants, then--say, the size of a pen tip--is to eliminate the power sources. "I think implants that carry photovoltaic receivers are particularly promising," he says. "The effect can be applied to tailor light-delivery mechanisms to efficiently channel light into tissues and onto these implants."

A study describing the process appears in the February issue of the journal Nature Photonics. Zahid Yaqoob, a postdoctoral fellow in electrical engineering at Caltech, performed most of the experiments reported in the paper. The other authors of the paper are Demetri Psaltis, professor of optics and dean of engineering, École Polytechnique Fédérale de Lausanne in Switzerland, and Michael S. Feld, a professor of physics at MIT.

Adapted from materials provided by California Institute of Technology.

From here

Gangliosida Berperan Penting Dalam Perkembangan Otak Anak

Jakarta (ANTARA News) - Nutrisi gangliosida, yang secara alami terdapat dalam air susu ibu, susu formula, daging dan telur, memiliki peran penting dalam pertumbuhan, serta perkembangan otak anak.

Peneliti senior dari Palmerston North, Selandia Baru, Dr.Paul McJarrow, PhD di Jakarta, Senin, menjelaskan bahwa gangliosida dalam asam sialat dibutuhkan dalam pertumbuhan, perkembangan, migrasi dan pematangan sel syaraf otak, serta pembentukan synaps (hubungan antar sel syaraf--red).

Lemak kompleks kelompok asam sialat yang terdiri atas komponen gula itu, menurut McJarrow, juga membantu proses transmisi sinyal synaps, pembentukan struktur otak dan menyimpan informasi.

"Penelitian yang dilakukan pada manusia juga menunjukkan bahwa suplementasi gangliosida dapat meningkatkan kemampuan belajar dan mengingat pada anak," jelasnya.

Ia menjelaskan, peran penting gangliosida dalam pertumbuhan dan perkembangan otak anak juga terlihat dari banyaknya konsentrasi gangliosida pada area abu-abu otak atau pada otak besar dan cerebral cortex yang merupakan area penting dalam pembentukan memori.

Namun demikian, menurut dia, hingga kini belum diketahui periode kritis kebutuhan gangliosida dalam formasi neuron maupun synaps. "Secara spesifik belum diketahui periode kritisnya, kapan gangliosida benar-benar dibutuhkan," katanya.

Ia menyarankan para ibu yang sedang hamil memaksimalkan asupan nutrisinya dengan mengonsumsi bahan makanan yang mengandung gangliosida seperti susu, daging dan telur.

Suplementasi gangliosida susu, katanya, juga bisa diberikan kepada bayi setelah periode pemberian ASI eksklusif usai.

Lebih lanjut dijelaskan, meskipun penting namun gangliosida saja tidak cukup untuk menyokong pertumbuhan dan perkembangan otak, nutrisi mikro lain seperti protein, kolin, AA-DHA, seng, besi, tembaga, iodium, folat dan vitamin A juga punya peran yang sama penting.

"Itu semua tidak berdiri sendiri, semua dibutuhkan untuk pertumbuhan dan perkembangan otak," kata dr.Soedjatmiko, SpA, MSi, dokter spesialis anak konsultan tumbuh kembang.

Ketua Divisi Tumbuh Kembang Departemen Pediatri Sosial Fakultas Kedokteran Universitas Indonesia itu juga menambahkan bahwa tanpa stimulasi memadai nutrisi saja tidak dapat mengoptimalkan pertumbuhan dan perkembangan otak anak.

"Seperti nutrisi, stimulasi juga sangat penting. Stimulasi bisa dilakukan dengan memberikan rangsang suara, rabaan, gerakan, coretan dan gambar pada saat bermain, menyusui, memandikan, jalan-jalan dan yang lainnya," demikian dr. Soedjatmiko. (*)

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Brain Signal Linked to Autism

By Emily Singer

By imaging the brains of adolescents with a high-functioning form of autism as they played a social-interaction game, scientists have identified a physiological deficit specific to the disorder. The researchers believe that the change is linked to a diminished sense of self. The findings, recently published in the journal Neuron, could help guide future research into the nature of autism and potentially lead to new ways to diagnose and treat the disorder.

"I think this is an exciting advance," says Uta Frith, a professor at University College London, in England, who wrote a preview of the paper for Neuron. Most studies find only subtle differences in people with high-functioning autism, "so it's quite impressive to find such a big difference," she says.

Autism is a complicated and heterogeneous developmental disorder marked by problems in language and social behavior. No medical tests exist to detect the disorder, so children are typically diagnosed based on doctors' observations. Scientists are avidly searching for more objective markers of autism, but identifying specific brain abnormalities has been a challenge.

Researchers at Baylor College of Medicine, in Houston, believe that they have now identified a specific physiological marker of the disorder. Read Montague, Pearl Chiu, and their colleagues scanned the brains of adolescents with Asperger's syndrome, a high-functioning form of autism, while they played an interactive trust game.

In the game, one person, designated the investor, chooses an amount of money to send to a second player, the trustee. The money is tripled en route, and the trustee must then decide how much to give back to the investor. When played by normal volunteers, the game unfolds in a very characteristic fashion: generous gestures are met with generous responses, while selfish ones inspire selfishness in return.

Brain activity also follows a stereotyped pattern. A study by Montague and his colleagues. published in 2006, imaged the brains of both the investor and the trustee as they played the game. The researchers discovered a specific signal in the cingulate cortex, part of the brain that integrates information from both the cortex and the body, that was detected only when the investor thought about how much money to give the trustee. A second signal was seen only when the investor received his or her return from the trustee. "We see a 'self, other, self, other' pattern," says Montague, director of the Human Neuroimaging Lab at Baylor. "We think that's an unconscious assessment of who the actions should be attributed to."

According to the new findings, people with Asperger's play the game just as a nonautistic person would, but they lack the characteristic "self" signal in the brain. Normal people lack the signal only when they think that they are playing against a computer, suggesting that autistic people view interactions with other people similarly to the way that normal people think about interacting with a computer. "This approach allows a somewhat objective look at something hopelessly subjective--sense of self," says John Gabrieli, a neuroscientist at MIT.

While the findings are clearly intriguing, it's not yet clear what they mean. One popular theory of autism is that people with the disorder lack a normal theory of mind--the ability to imagine the thoughts and actions of others. Identifying a specific deficit linked to thoughts of self could help narrow down what has gone wrong in that process. "People think autism is linked to a lack of understanding of what a partner is doing," says Chiu. "But maybe they don't understand their own role in the social exchange."

Other scientists interpret the results further, suggesting that this signal is linked to a sort of internal reputation assessment in the brain. "If you are a normal person, when you invest money in the game, you are thinking about how you will look in the eyes of your partner," says Frith. "That's precisely what the theory of mind hypothesis would project is wrong with people with autism."

Other autism experts are unwilling to make such a leap. "I'm skeptical about how much [the Baylor College study] tells us about which capacities are intact and engaged in autism," says Matthew Belmonte, a scientist at Cornell University, in Ithaca, NY. "I'm not convinced they have a deficit at all. Maybe they have adopted a different cognitive strategy."

Regardless of the deeper meaning of their findings, Montague and his team ultimately hope to develop the brain-imaging results into a diagnostic test. They have converted the activity signal from the cingulate cortex into a simple numerical score, which correlates well with a clinical test for the severity of autism. Eventually, they hope to be able to show, for example, "that if you get a 3 rather than a 14, you are 80 percent more likely to be a high-functioning autistic," says Montague. Such a tool could potentially also be used to test the effectiveness of new behavioral treatments, he says.

However, much work remains to be done before such a test could be used in a doctor's office. "We need to make it simpler and test people with a wider range of IQs," says Montague. The Asperger's volunteers in the current study had an above-average IQ.

from here

Medicine From Milk: Gene Therapy Transforms Goats Into Pharmaceutical Factories

ScienceDaily (Feb. 1, 2008) — University of Pennsylvania researchers have used gene therapy to reduce the time it takes to breed large animals capable of producing therapeutic proteins in their milk, such as insulin or those that fight cancer. This represents a significant milestone in drug development, as current methods involve cloning, which takes more time and generally costs more.

"Having an easier way to harness nature's power to produce large quantities of specific proteins in milk could increase the availability of drugs for people who could otherwise not afford these treatments," said Ina Dobrinski, one of the researchers on the study.

The study also is significant because it may also be a new way to eliminate diseases in future generations of animals, such as those used for livestock. Here's why: To get the goats to produce specific proteins, the researchers used radiation to kill a portion of a male goat's germ cells (the cells that produce sperm). Then they used a modified adeno-associated virus (a well studied and tolerated gene therapy vector) to insert a gene in the remaining cells. Once the new gene took hold in the germ cells, a predictable number of female offspring produced the desired protein in their milk.

The advance is immediately valuable for pharmaceutical development and biology research, but a similar approach could be used to bolster the food supply by eliminating genetic disorders in animals over several generations. It is also possible that once perfected, this technique could eliminate disease genes in humans over several generations, assuming ethical concerns can be resolved adequately.

This study is published in the February 2008 print edition of The FASEB Journal.

"For thousands of years, people have domesticated cows and goats to make milk, butter and cheese. And for thousands of years dairy products have been used as folk remedies for practically every human illness. Most have been completely ineffective." said Gerald Weissmann, MD, editor-in-chief of The FASEB Journal. "So it is reassuring that modern science would find a way to use the milk we drink to yield of drugs that actually work."

Adapted from materials provided by Federation of American Societies for Experimental Biology, via EurekAlert!, a service of AAAS.

A New Tool To Determine Protein Structures

By Corinna Wu

Synchrotrons are huge facilities that can produce intense, high-quality x-ray beams for scientific purposes. They usually span the size of a football field and cost hundreds of millions of dollars to build and operate. But now, researchers at Lyncean Technologies, a startup in Palo Alto, CA, have shrunk the synchrotron to the size of a room. This miniature synchrotron offers scientists a new way to perform high-quality x-ray experiments in their own labs.

Lyncean has built a prototype synchrotron and is constructing another to be installed this year at the Scripps Research Institute in La Jolla, CA. The new synchrotron will be used by the Accelerated Technologies Center for Gene to 3D Structure, which is part of the National Institutes of Health's Protein Structure Initiative.

The tabletop instrument is "not as powerful as the big synchrotrons," says Ronald Ruth, Lyncean's president and chief scientist. "But on the other hand, it's far cheaper, and it's very compact." He likens the national synchrotrons to supercomputers, where many users must compete for limited time on one of the beams. "[The synchrotrons] address the state-of-the art," Ruth says. "They push the envelope. But their impact is only as broad as the number of people that are willing to travel to go there." The miniature synchrotron is more like a PC, he says, shared by a few users and readily available.

X-rays are useful in probing the properties of materials, since their wavelength is about the same size as atoms and the chemical bonds between them. For example, x-ray crystallography is an important method in determining protein structure. X-rays diffract as they pass through a protein crystal, generating a characteristic interference pattern. By analyzing the pattern, scientists can deduce the arrangement of the atoms and thus determine the protein's structure.

For these kinds of studies, synchrotron radiation has advantages over ordinary x-ray sources: It's a hundred million times brighter and highly concentrated, which allows for very precise, high-resolution experiments. Synchrotrons also produce a continuous source of x-rays, instead of the short bursts generated from common x-ray tubes. And a synchrotron's light is tunable, so researchers can match the energy to the material being probed.

The quality of light from the miniature synchrotron is as good as the big machines, says Franz Pfeiffer, a physicist at the Paul Scherrer Institute and École Polytechnique Federale in Lausanne, Switzerland. "That's what makes it so attractive," he says. "[It] combines the benefit of having something relatively small with the advantages of the extremely brilliant beam that is available through synchrotrons. It's a very nice thing to have."

Ruth first determined that a miniature synchrotron might be possible in the late 1990s, when hewas a professor at the Stanford Linear Accelerator Center. Ruth and a graduate student, Zhirong Huang, were looking for a way to cool electron beams by getting them to radiate. They found that hitting the beams with a laser not only cooled them effectively, but also generated x-rays.

This effect proved to be the key to shrinking the synchrotron down to size. Big synchrotrons use magnetic "undulators" that wiggle the electron beam from side to side as it circulates around a large storage ring. Ruth explains that that wiggle, on the order of one centimeter, generates x-rays that are thrown off on a tangent to the circle, much like a spinning searchlight shines light.

The miniature synchrotron uses only a moving laser pulse that interacts with the electron beam each time it goes around the storage ring, which fits on a tabletop. The wiggle is one ten thousandth as small--just one micrometer--and the x-rays are given off in a single beam.

From here

Transgenik Yes, But . . .

Jakarta-RoL--"Prinsipnya bagi kami tidak masalah, bahkan kami dukung upaya itu," kata Sekjen Himpunan Kerukunan Tani Indonesia (HKTI) Rachmat Pambudy pada diskusi pakar bertema "Keunggulan Bioteknologi dan Solusi Menuju Kemandirian Pangan" di Jakarta, Selasa.

pernyataan diatas disampaikan sebagai dukungan petani yang tidak akan menghambat upaya peningkatan produktivitas pertanian melalui rekayasa genetik (transgenik) selama produk tersebut aman pangan, aman lingkungan dan menguntungkan bagi para petani, selain itu,produk transgenik itu harus hasil riset dan teknologi dari dalam negeri oleh ahli Indonesia sendiri, ditanam oleh para petani dalam negeri, dan demi kepentingan bangsa dan ketahanan pangan nasional.

"Jadi produk transgenik itu jangan sampai dikembangkan perusahaan multinasional yang datang ke Indonesia, menanam di tanah kita, lalu terjadi persaingan hasil pertanian mereka dengan petani kita, lalu mereka yang memenangkan pasar dan kita menjadi tergantung. Ini tidak benar," katanya.

Hasil riset rekayasa genetika itu yakni kedelai TH (toleran herbisida), kapas Bt (toleran serangga pengerek batang), kapas TH, jagung TH dan jagung Bt oleh sejumlah perusahaan dan sudah dinyatakan aman sehingga mereka tinggal mengurus sejumlah izin lain.Sedangkan riset tanaman rekayasa genetik di Indonesia, menurut Kapuslit Biotek LIPI Dr Bambang Prasetya, sebenarnya sudah dilakukan, tetapi masih dalam taraf riset, belum dilepas dan belum siap untuk ditanam secara komersial.

Pihaknya, lanjut dia, masih ragu-ragu untuk secara intensif melakukan riset rekayasa genetika apa lagi sampai melepas hasil-hasil riset tersebut karena selain masih kontroversi juga belum didukung peraturan yang lengkap.

Rekayasa genetika mampu meningkatkan produktivitas hasil pertanian dengan mengurangi banyak komponen biaya produksi seperti pestisida, penggunaan air, ketahanan terhadap lahan kering dan asam dan lain-lain yang bisa menguntungkan petani. antara/mim

from here

Fresh Insight into Evolution

By Emily Singer

It's a tantalizing thought worthy of X-Men-inspired daydreams: are some of us, for better or for worse, evolving faster than others? Growing evidence suggests that rates of genetic recombination--one of the driving forces of human evolution--vary greatly between individuals. Two new studies shed further light on the inner workings of this gene-shuffling process, highlighting differences in the way men and women rearrange the DNA that they pass on to their children. The findings could help scientists understand disorders such as miscarriage and Down syndrome, which are linked to errors in recombination.

During recombination, corresponding maternal and paternal chromosomes align within cells and swap bits of DNA. These cells eventually develop into sperm and eggs, endowing future offspring with a different configuration of genes than their parents. "Recombination constitutes one of the most powerful means by which new combinations of genetic variants are generated in the genome," says Kari Stefansson, chief executive officer of deCODE Genetics, in Iceland, and senior author of one of the studies.

Previous research shows that recombination is often localized to specific spots on the genome, known as hot spots. Some people's genomes undergo this swap more than other people's, with apparently profound consequences. In 2005, Stefansson's group at deCODE found that women with higher recombination rates had more children, suggesting that evolution has selected for molecular mechanisms that create diversity.

Scientists study recombination by comparing genetic variation in parents and their children. New techniques to analyze huge numbers of genetic variations, commonly used to identify genes linked to disease, are now allowing a more detailed analysis of recombination than ever before. (See "Genes for Several Common Diseases Found.") In one such study, published Thursday in the online version of the journal Science, researchers from the University of Chicago generated a high-resolution map of recombination hot spots by analyzing the DNA of 725 people. The volunteers came from 82 families of Hutterites, a genetically similar group of European immigrants who settled in the Dakotas in the 19th century.

That map allowed researchers to analyze how specific hot spots varied between men and women, and parents and children. "Some individuals use some hot spots more than others," says Graham Coop, a researcher at the University of Chicago who led the work. Coop and his collaborators also found that men and women had different recombination rates and tended to use different hot spots for recombination. In addition, that pattern of hot-spot usage seemed to be inherited. "That suggests differences in recombination machinery between indviduals," says Coop. He ultimately hopes to identify the genes that control recombination.

Stefansson and his colleagues do just that in a second study, also published Thursday in Science. The researchers scanned the genomes of 20,000 people for specific genetic variations linked to recombination rate. They identified two variations within a gene known as RNF212 that together accounted for 22 percent and 6.5 percent of paternal and maternal variation, respectively. Little is known about the function of the gene.

Surprisingly, these variations had opposite effects in men and women: the mutation that increased recombination in women did the opposite in men, and vice versa. The findings suggest an evolutionary mechanism for keeping control of genetic diversity. "It's important to increase diversity, but if it goes unchecked, it's likely to lead to instability in the genome that could be dangerous," says Stefansson. "If you have the same sequence variant influencing recombination in one direction in men and the other direction in women, you have put together a mechanism to keep recombination rates within certain limits."

Both studies shed light on the basic underpinnings of human evolution, which could ultimately impact human health. For example, abnormal recombination can result in miscarriage. Older women, who have higher rates of miscarriage, tend to have children whose genomes show evidence of higher recombination rate. A better understanding of the mechanisms underlying this observation could eventually lead to new fertility treatments.

from here

Ayam Lokal Tahan Banting

Rabu, 23 Januari 2008 | 14:21 WIB

TEMPO Interaktif, Jakarta:

Ayam yang satu ini memang istimewa. Bulu, kaki, jengger, paruh, dan lidahnya berwarna hitam pekat. Bahkan daging dan darahnya pun hitam. Karena itu, ayam cemani dipercaya memiliki kekuatan mistis. Ternyata ayam dari Jawa Tengah ini juga punya kekuatan lain, yaitu tahan terhadap serangan virus flu burung.

Begitulah hasil penelitian Sri Sulandari dan M. Syamsul Arifin Zein, dua peneliti genetika zoologi di Pusat Penelitian Biologi, Lembaga Ilmu Pengetahuan Indonesia (LIPI). Mereka telah meneliti sampel darah dari 15 galur ayam lokal Indonesia dan ayam kampung yang selamat dari wabah flu burung di beberapa daerah.

Hasil analisis terhadap gen Mx terhadap populasi ayam Indonesia itu menunjukkan ayam cemani memiliki resistensi terhadap virus flu burung yang paling tinggi, 0,89 persen, dibanding galur ayam lainnya. Adapun ayam kapas memiliki resistensi terendah, hanya 0,35 persen.

Namun, bukan berarti semua ayam cemani resisten terhadap virus itu. Zein menekankan bahwa hasil penelitian ini tidak berlaku untuk semua populasi ayam cemani yang tidak ditelitinya. "Dalam penelitian ini, ayam cemani yang kami ambil darahnya berasal dari Kedu, Temanggung," kata Zein. "Riset menunjukkan 88 persen dari populasi cemani yang diteliti memiliki protein yang resisten virus flu burung. Kalau ada populasi ayam cemani lain yang bertentangan dengan penelitian ini, bisa saja. Kebetulan yang kita ambil di pusat Cemani, kondisinya bagus."

Ketahanan ayam cemani itu ternyata ditentukan oleh gen Mx. Para ilmuwan telah mengetahui fungsi gen itu sebagai penentu kemampuan ayam untuk resisten atau justru rentan terhadap serangan virus avian influenza. Gen ini ditemukan pada beberapa hewan vertebrata, seperti mamalia, unggas, dan ikan, bahkan beberapa avertebrata.

Mutasi pada gen yang berada dalam kromosom 1 dengan 14 exon itulah yang menentukan resistensi ayam terhadap flu burung. Mutasi alel A (genotipe AA) menjadi G (genotipe GG) pada nukleotida ke-1.892 pada exon ke-13 itu menyebabkan adanya perubahan asam amino dari serin (AGT) menjadi asparagin (AAT).

Perubahan alel A menjadi G ini membuat unggas rentan terhadap flu burung, karena membentuk protein yang seharusnya mampu melawan. Alel A resisten terhadap serangan virus avian influenza, alel G rentan terhadap serangan virus itu, sedangkan alel R (genotipe AG) bisa resisten tapi juga bisa rentan.

Sulandari mengatakan hasil analisis terhadap fenomena mutasi alel G/A terhadap populasi ayam lokal di Indonesia itu menunjukkan bahwa ketahanan ayam lokal Indonesia terhadap virus tersebut cukup tinggi. "Rata-rata frekuensi alel A di atas 50 persen itu bagus," katanya. "Kalau kurang dari itu rentan karena, dalam populasinya, umumnya (ayam) memiliki alel GG, sedangkan alel AA tahan banting."

Selain cemani, ayam merawang dari Kepulauan Bangka Belitung yang diteliti dalam riset sejak 2007 itu menunjukkan frekuensi alel A yang tinggi. Begitu pula ayam pelung yang mereka teliti dari daerah Ciamis.

Sri Sulandari menyatakan penelitian gen Mx dari 877 sampel ini juga menghasilkan temuan penting, yaitu ayam yang selamat dari wabah avian influenza di Banten, Lampung, dan Sumatera Utara memiliki daya resisten cukup tinggi. "Frekuensi alel A ayam kampung di daerah itu cukup tinggi, antara 0,60 dan 0,73," katanya.

Ayam hutan merah, yang merupakan nenek moyang dari ayam domestikasi, mempunyai frekuensi alel A 0,49 persen. Angka yang diperlihatkan ini masih dalam kisaran frekuensi alel A yang dimiliki ayam lokal Indonesia. "Selain ayam hutan hijau (Gallus varius), secara keseluruhan ayam-ayam yang digunakan dalam penelitian ini, ayam kampung dan ayam hutan merah, mempunyai frekuensi alel resisten cukup tinggi," ujarnya.

Faktor daya tahan terhadap serangan flu burung ini, kata Zein, bisa dimanfaatkan dalam program pemuliaan. Secara alamiah, ayam dengan alel genotipe AA mampu melakukan perlawanan terhadap serangan flu burung. "Ayam dengan alel A akan memiliki keturunan dengan alel A pula, maka data ini penting sekali untuk keperluan breeding," ujarnya. "Kami tidak terlalu concern dengan ayam cemani resisten atau tidak, tapi sistem ini bisa digunakan untuk breeding."

Zein menyatakan bahwa dengan sistem ini dia bisa menciptakan populasi ayam yang 100 persen tahan serangan virus mematikan itu. Bila ada orang yang ingin membuat peternakan ayam kampung, bisa bekerja sama dengan laboratorium dengan menyeleksi induk sehingga menghasilkan keturunan yang tahan virus. "Yang tahan dikembangkan, yang jelek dibuang," katanya.

Cara membuat keturunan tahan virus flu burung sebenarnya sederhana, dengan memeriksa gen Mx ayam yang hendak dikembangbiakkan. "Misalnya kita ambil ayam jantan dan betina beralel AA," ujarnya. "Kalau beralel AA bertemu dengan AA, anaknya pasti AA. Kalau AG dengan AG, kadang alel bergenotipe GG keluar."

Selain menciptakan generasi ayam tahan flu burung, penelitian ini bisa digunakan bagi pengambil kebijakan dalam mengatasi wabah flu burung. "Setelah serangan (flu burung), kita maunya menjelaskan kepada pemerintah bahwa yang hidup itu adalah yang tahan, tapi akhirnya dibunuh," kata Zein. "Jadi yang nggak resisten mati karena penyakit, tapi yang resisten mati dibunuh."

Langkah membumihanguskan peternakan yang terkena wabah itu, kata Zein, kurang tepat. Jika kebijakan depopulasi--membunuh semua unggas yang hidup berbagi tempat dengan unggas mati--itu diteruskan, genetic resource Indonesia terancam bahaya. "Kalau ayam yang tahan virus dibunuh, sumber daya genetik kita habis, akhirnya kita punya ayam berkualitas lembek," ujarnya. "Sehingga bisa terjadi seperti kasus kedelai, bergantung pada Amerika terus. Kita tidak menanam, impor mahal."

TJANDRA DEWI

from here

Proyek 1000 Genom

Amerika, Inggris dan Cina kini bekerja sama dalam Proyek 1000 Genom. Proyek ini bertujuan untuk memetakan genom manusia terbaru dengan data variasi DNA biomedis paling lengkap dan lebih detail menurut Richard Durbin dari Sanger Institute. Proyek ini melibatkan institusi Wellcome Trust Sanger Institute dari Inggris, National Human Genome Research Institute (NHGRI) dari Amerika, dan Beijing Genomics Institute-Shenzhen, Cina.

Proyek 1000 genom ini mungkin untuk dilakukan saat ini karena teknologi pengurutan genetika, bioinformatika dan teknik lainnya makin mengalami kemajuan. Dengan proyek ini upaya untuk menemukan faktor genetika yang terlibat dalam penyakit dan kesehatan manusia daapt dilakukan dengan lebih efektif lagi.

Perbedaan yang ada pada individu merupakan pengaruh dari satu persen DNA, sehingga dengan riset dalam 1000 genom ini, informasi mengenai DNA akan lebih mendetail. Perbedaan satu persen pada DNA sering kali bertanggung jawab atas perbedaan dalam kerentanan terhadap penyakit dan reaksi pengobatan. Ilmuwan telah mendaftarkan puluhan wilayah variasi genom manusia yang spesifik (haplotipe) dan mengasosiasikannya dengan penyakit umum, seperti penyakit jantung koroner, kanker payudara, arthritics, dan penyakit akibat penuaan.

Peta DNA yang berhasil disusun tahun 2000 lalu masih belum terlalu detail, oleh karena itu ilmuwan ingin mengembangkannya lagi agar peta DNA yang ada saat ini menjadi lebih detail dan gambaran genom akan menjadi lebih jelas dalam menemukan faktor genetika suatu penyakit.

Proyek ini akan memetakan DNA dari beragam kelompok etnis yang spesifik, termasuk Yoruba di Ibadan, Nigeria; Chinese di Denver, Colorado; Chinese di Beijing; Toscani di Italia, India Gujarati di Houston, Texas; orang Meksiko di Los Angeles; serta warga keturunan Afrika di barat daya Amerika Serikat.

Dengan memanfaatkan teknologi sequencing dan metode komputasional terbaru, diharapkan dapat memberikan peta genom lengkap bagi ilmuwan biomedis, yang akan memaparkan segala bentuk variasi sampai tingkat satu persen dan ini akan mengubah cara ilmuwan untuk mempelajari penyakit genetis kata Francis Collins, wakil NHGRI.

Tempo Interaktif

Otak Korslet

Sabtu, 26 Januari 2008 | 13:30 WIB

TEMPO Interaktif, Davis :

Mencari wajah yang kita kenal di keramaian ternyata sulit dilakukan oleh otak manusia. Hasil penelitian terbaru membuktikan otak memproses lautan wajah manusia menjadi koleksi garis dan sudut yang kabur. Hasilnya: kebingungan.

Fenomena ini disebut "crowding" dan terjadi ketika seseorang gagal mengenali obyek individual di lingkungan yang semrawut. Malfungsi identifikasi penglihatan ini terjadi karena terjadi sedikit "korsleting" di otak kita, yang berusaha mendata informasi visual yang membanjir yang masuk setiap detik.

"Fenomena ini mengungkapkan salah satu mekanisme fundamental sistem visual mata dan otak kita, yang berusaha mengkonsolidasikan atau menyaring masuknya begitu banyak informasi menjadi sedikit fakta yang berarti," kata David Whitney, psikolog di Centre for Mind and Brain di Universitas California, Davis, Amerika Serikat.

Whitney dan rekan-rekannya melakukan lima eksperimen untuk mengukur rekognisi para partisipan untuk mencari wajah atau rumah yang familiar dari kerumunan wajah dan rumah. Sebuah gambar akan tampil di layar komputer dan obyek penelitian harus mengindikasikannya dengan cepat di mana orang atau rumah yang dikenal.

Hasilnya, para partisipan amat sulit mengidentifikasi wajah yang berada di kerumunan wajah lainnya, sebagaimana yang terjadi di jalanan. Sebaliknya, partisipan tidak mengalami kesulitan mengenali obyek rumah yang menjadi target.

Para peneliti menyatakan hasil observasi dengan menggunakan layar komputer ini berkorelasi lurus dengan kehidupan nyata. Gambar-gambar wajah yang diterima otak saling mengganggu satu sama lain membuat otak kesulitan "memungut" satu wajah dari keramaian.

Hasil studi yang dipublikasikan di Journal of Vision di Amerika Serikat ini memiliki implikasi bahwa kebanyakan individu mengalami masalah identifikasi dalam penglihatan. Dalam jangka panjang, penemuan ini dapat menolong para ilmuwan mengembangkan sistem visual artifisial yang lebih baik dari sistem penglihatan manusia.

AMAL IHSAN | LIVESCIENCE

from here

Bio News Groups

Temans, kalo ente tertarik dengan perkembangan bioteknologi & bioengineering, ada groups yg mungkin bisa teman teman ikutin. groupnya dibuat di google, namanya

bioteknologia@googlegroups.com

moderatornya akan menyediakan artikel2 seputar perkembangan bioteknologi & bioengineering dalam bahasa indonesia dan bahasa inggris.

please join with us to develop biotech in Indonesia.

Here are the essentials:

* Group name: bioteknologia
* Group home page: http://groups.google.com/group/bioteknologia?hl=en
* Group email address bioteknologia@googlegroups.com

Looking into the Brain with Light

By Michael Chorost

A new noninvasive diagnostic technology could give doctors the single most important sign of brain health: oxygen saturation. Made by an Israeli company called OrNim and slated for trials on patients in U.S. hospitals later this year, the technology, called targeted oximetry, could do what standard pulse oximeters can't.

A standard pulse oximeter is clipped onto a finger or an earlobe to measure oxygen levels under the skin. It works by transmitting a beam of light through blood vessels in order to measure the absorption of light by oxygenated and deoxygenated hemoglobin. The information allows physicians to know immediately if oxygen levels in the patient's blood are rising or falling.

Prior to the development of pulse oximeters, the only way to measure oxygen saturation was to take a blood sample from an artery and analyze it in a lab. By providing an immediate, noninvasive measure of oxygenation, pulse oximeters revolutionized anesthesia and other medical procedures.

While pulse oximeters have become accurate and reliable, they have a key limitation: they can't measure oxygen saturation in specific areas deep inside the body. Because pulse oximeters measure only the blood's overall oxygen levels, they have no way of monitoring oxygen saturation in a specific region. This is especially problematic in the case of brain injuries, since the brain's oxygenation can then differ from the rest of the body's.

Information on oxygenation in specific regions of the brain would be valuable to neurologists monitoring a brain-injured patient, as it could be used to search for localized hematomas and give immediate notice of hemorrhagic strokes. When a stroke occurs, an area of the brain is deprived of blood and thus oxygen, but there is no immediate way to detect the attack's occurrence.

CT and MRI scans give a snapshot of tissue damage, but they can't be used for continuous monitoring. It can also be very difficult to conduct such scans on unconscious patients hooked up to life-support devices.

Wade Smith, a neurologist at the University of California, San Francisco, and an advisor to OrNim, points out that, while cardiologists have devices to monitor hearts in detail, neurologists have no equivalent tool. With brain-injured patients, Smith says, "the state of the art is flying blind."

OrNim's new device uses a technique called ultrasonic light tagging to isolate and monitor an area of tissue the size of a sugar cube located between 1 and 2.5 centimeters under the skin. The probe, which rests on the scalp, contains three laser light sources of different wavelengths, a light detector, and an ultrasonic emitter.

The laser light diffuses through the skull and illuminates the tissue underneath it. The ultrasonic emitter sends highly directional pulses into the tissue. The pulses change the optical properties of the tissue in such a way that they modulate the laser light traveling through the tissue. In effect, the ultrasonic pulses "tag" a specific portion of tissue to be observed by the detector. Since the speed of the ultrasonic pulses is known, a specific depth can be selected for monitoring.

The modulated laser light is picked up by the detector and used to calculate the tissue's color. Since color is directly related to blood oxygen saturation (for example, arterial blood is bright red, while venous blood is dark red), it can be used to deduce the tissue's oxygen saturation. The measurement is absolute rather than relative, because color is an indicator of the spectral absorption of hemoglobin and is unaffected by the scalp.

Deeper areas could be illuminated with stronger laser beams, but light intensity has to be kept at levels that will not injure the skin. Given the technology's current practical depth of 2.5 centimeters, it is best suited for monitoring the upper layers of the brain. Smith suggests that the technology could be used to monitor specific clusters of blood vessels.

While the technology is designed to monitor a specific area, it could also be used to monitor an entire hemisphere of the brain. Measuring any area within the brain could yield better information about whole-brain oxygen saturation than a pulse oximeter elsewhere on the body would. Hilton Kaplan, a researcher at the University of Southern California's Medical Device Development Facility, says, "If this technology allows us to actually measure deep inside, then that's a big improvement over the limitations of decades of cutaneous versions."

Michal Balberg, the CEO and cofounder of OrNim, thinks that it may ultimately be feasible to deploy arrays of probes on the head to get a topographic map of brain oxygenation. In time, brain oxygenation may be considered a critical parameter that should be monitored routinely. Balberg says, "Our development is directed toward establishing a new brain vital sign that will be used to monitor any patient [who's] unconscious or under anesthesia. We believe that this will affect patient management in the coming decade in a manner comparable to pulse oximeters."

Michael Chorost covers medical devices for Technology Review. His book about cochlear implants, Rebuilt: How Becoming Part Computer Made Me More Human, was published in 2005.

From here

Genetic Variant Predicts Heart Disease Risk

By Apoorva Mandavilli

Testing for a genetic variation could predict the likelihood that a patient will respond well to certain statins. But some researchers say it's too soon to use the variation to determine treatment.

Researchers from Celera reported yesterday in the Journal of the American College of Cardiology that a single substitution in the sequence of a gene called KIF6 makes people both more susceptible to heart attacks and more responsive to certain drugs that lower cholesterol. Though there is no known biological explanation linking the variation to heart disease, the study found that it increases the risk of heart attacks and strokes by 55 percent.

Celera, the company best known for sequencing the human genome, examined 35 single-nucleotide polymorphisms (SNPs) in 30,000 patients. Of those, "KIF6 is by far the most significant," says Thomas J. White, chief scientific officer at Celera. In fact, nearly 60 percent of the study population was found to carry the KIF6 variant. (According to the study, these findings take into account other factors, such as smoking, high blood pressure, and cholesterol levels.)

The researchers also found that carriers of the KIF6 variant responded better to the cholesterol-lowering drugs pravastatin (Pravachol) and atorvastatin (Lipitor). For example, among patients with the genetic variation, those who took pravastatin were 37 percent less likely to experience a heart attack than those who took the placebo. Those without the genetic variation who took the drug were only 14 percent less likely to experience a heart attack than those who took the placebo. Statins are big sellers for the pharmaceutical industry. In 2006, Lipitor, the world's best-selling drug, brought in $13 billion in global sales.

"This is one of the first studies to show an interaction with therapy" and genotype, says Marc Sabatine, professor of medicine at Harvard Medical School and a coauthor on one of the papers. "That is very exciting to see."

Surprisingly, the researchers found that KIF6 doesn't appear to work by lowering levels of LDL or "bad" cholesterol, the standard by which drugs used to prevent heart attacks are normally measured. White says that KIF6 may instead act by stabilizing "vulnerable plaques," which are particularly prone to triggering heart attacks.

Celera is developing a diagnostic that would test for the KIF6 variant and expects to launch it in a few months.

But some experts caution that it may be premature to introduce such diagnostic tests before there is further confirmation of KIF6's role in heart disease.

"Even if there are beneficial results, the standard should be that you need to document that knowing the genetic information is clinically useful," says Sekar Kathiresan, director of preventive cardiology at Massachusetts General Hospital.

Coronary heart disease caused one of every five deaths in the United States in 2006, so scientists have for quite some time been on the hunt for genes linked to heart attacks.

Rapid advances in technology have made that task much easier. At the same time, many of the genetic links to heart disease identified so far haven't held up on further analysis. At present, the only credible link is to a variant of the gene 9p21, identified last year by the Icelandic company deCODE Genetics, says Kathiresan. DeCODE offers a $200 diagnostic test for the 9p21 variant. (See "Gene Variant Linked to Heart Disease.")

A second gene, PCSK9, also looks promising, Kathiresan adds. "Nearly everything else is in the realm of 'possible but not definite.'"

It's good that KIF6 has been identified as a potential risk factor in several different studies, Kathiresan says. In each of the studies, he notes, there is less than a one-in-20 probability that the finding is a result of chance, which is generally considered an acceptable threshold for statistical significance.

But because of the high possibility of false positives, the threshold for genome-wide association studies should be much higher, on the order of one in 20 million, Kathiresan says. Both the 9p21 and the PCSK9 pass that test, he says.

"The key issue here is we don't know if these [KIF6 studies] are real results," Kathiresan says. "You need to show that it is clinically useful, and they have not crossed that threshold."

From here

Detecting Asthma Irritants

By Brittany Sauser

Researchers at Georgia Tech Research Institute (GTRI) in Atlanta have developed a portable sensor system to monitor the air quality for people suffering from asthma. The device is a combination of sensors that measure the level of chemicals in the air thought to cause asthma attacks, such as ozone, volatile organic compounds, and formaldehyde. It is lightweight and small enough to fit into a patient's pocket, so exposure levels can be continuously monitored.

The only way that we are going to understand how environmental factors affect asthma is if we can measure a person's exposures on a day-to-day basis, says Charlene Bayer, the leader of the Environmental Exposures and Analysis Group at GTRI and the sensor system's principal investigator. "To do so, we need a device like this that can hold numerous sensors in a small, portable package.".

An estimated 20 million Americans suffer from asthma, according to the National Institutes of Health (NIH), and identifying the triggers of an attack is currently a guessing game. "There are a few devices on the market that measure one or two chemicals, but they are stationary and the size of a desktop computer," says Mark Jones, the chief executive officer of Keehi Technologies and the lead engineer developing the sensor system.

Currently, the only way to control an asthma attack is with medication, or "trigger avoidance." In 2007, the total health-care costs of asthma in the United States were approximately $19.7 billion, according to the NIH.

"Research has shown that if you can reduce the triggering of an asthma attack, you will reduce the impact of the disease," says Mark Millard, the director of the Baylor Martha Foster Lung Care Center at Baylor University Medical Center in Dallas, TX. The new sensor system, he says, is really trying to answer the question, "What are the triggers for people with asthma?"

The device is about the size of a cell phone and contains a total of five sensors that measure different possible asthma triggers: ozone, nitrogen dioxide, formaldehyde, carbon dioxide, and total volatile organic compounds--the brew of chemicals that are emitted as gases from products such as paints, cleaning supplies, and building materials. The device also includes temperature and humidity sensors and a clock, to put a time stamp on the measurements. The researchers used sensors already on the market and kept the device small by outfitting the sensors on a two-sided circuit board.

Establishing a timeline is important for late-phase reactions, says Millard, since reactions to compounds such as formaldehyde may happen four to six hours after a patient is exposed. "Now we can look at the data and know that a patient was exposed to a lot of those compounds and that could be the trigger."

To measure the air quality, a small motor in the device sucks in air through an intake hose. Before the air passes over the sensors, it encounters a small filter that removes particulates, such as dust and pollen. The mass of the filter is measured before and after a sampling period to determine the total amount of particles. The air is then evenly distributed over the sensors.

"It takes about 30 seconds for the air to pass through the device and the data to be stored, and then it goes to sleep for another minute. In one hour it takes approximately 50 or 60 samples," says Jones.

The device can be worn for up to 24 hours before the particle filter needs to be replaced and the memory on the device is full. The data can be downloaded from the sensor system onto a computer.

Millard says the device is unique and innovative, but that he would like to see its capabilities expanded to measure tobacco smoke. He would also like to be able to separate out the particle measurements so they can be measured in real time--an upgrade that Bayer says will be introduced once the device is commercialized. Bayer would also like to get more specific readings on the different volatile organic compounds.

"We would like to get to the point where we can pop certain sensors in and out so a patient can target it towards their particular needs," says Bayer. "Asthma is a very complicated disease and there are a number of different airborne exposures that can exacerbate an asthma attack. This technology will allow us to find the source of exacerbation and understand the health impacts," she says.

The researchers at GTRI are currently in talks with an undisclosed company to commercialize the device, says Bayer. The initial target users will be asthma patients but the device will be open for use by others who want to study environmental exposures.

From here

Sel Penyebab Leukemia Ditemukan

Selasa, 29 Januari 2008 | 13:28 WIB

TEMPO Interaktif, Oxford:
Tim peneliti menemukan bahwa kedua anak kembar tersebut memiliki sel tunas abnormal praleukemia dalam darah mereka. Sel itu bisa "tidur" dalam sumsum tulang atau berkembang menjadi sel tunas leukemia. Hasil ini dikonfirmasi oleh eksperimen yang menggunakan sel tali pusar manusia.

"Penelitian ini berarti kami dapat mengetes apakah penanganan leukemia lymphoblastic akut pada anak bisa dikaitkan dengan menghilangnya dan berkembangnya sel tunas leukemia," kata Profesor Tariq Enver dari Unit Hematologi Molekuler Universitas Oxford, yang memimpin penelitian tersebut. "Mulai saat ini, upaya penyembuhan bisa difokuskan pada upaya membidik sel tunas praleukemia dan sel tunas kanker dengan obat yang ada atau yang akan kita kembangkan."

Upaya penyembuhan yang terfokus, menurut Tariq, bisa menghindari efek samping pengobatan kanker kemoterapi yang menyakitkan dan terkadang justru membahayakan kondisi tubuh pasien. Hal ini sangat penting karena terbukti, Olivia, salah satu anak kembar yang terkena leukemia, mengalami kebutaan di sebelah matanya akibat infeksi yang tidak bisa dilawan tubuhnya saat kemoterapi.

Para ilmuwan telah melacak kemungkinan sel tunas prakanker itu akibat fusi abnormal dari dua gen yang terjadi selama kehamilan ibu. Fusi ini menghasilkan protein hibrida, sebuah "kesalahan" genetik yang terjadi secara acak dan menyebabkan sel menjadi terjangkit leukemia. Gen yang diambil dari si kembar lantas ditransplantasikan ke tikus laboratorium yang mengkonfirmasi adanya hubungan langsung antara malfungsi genetik dari sel tunas tersebut dan leukemia.

Lembaga donor Inggris yang membiayai penelitian itu, Leukemia Research and the Medical Research Council, dan Rumah Sakit Great Ormond Street menyatakan sangat gembira atas penemuan itu dan berharap penelitian dilanjutkan ke upaya mencegah dan mengobati penyakit tersebut.

AMAL IHSAN | SCIENCEDAILY

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Next Steps for Stem Cells

By Emily Singer

Searching the brain of an Alzheimer's patient for clues into the origin of the disease is like trying to find the cause of a plane crash in the wrecked aftermath. However, a recent breakthrough in stem-cell research could generate new cellular models that allow scientists to study disease with unprecedented accuracy, from its earliest inception to a cell's final biochemical demise.

Last November, two groups of scientists announced that they had independently achieved one of the stem-cell field's biggest goals: the ability to reprogram adult cells into embryonic-like stem cells without the need for human embryos. (See "Stem Cells without the Embryos.") The findings garnered extensive media attention, largely because the new method obviated the need for human embryos, a major ethical minefield that has stymied research.

But scientists at stem-cell labs around the world are excited for another reason. The technique creates cells that are genetically matched to an individual, meaning that it's now possible to create novel cell models that capture all the genetic quirks of complex diseases. "Being able to have human cells with human disease in a dish accessible for testing is a real boon to technology and to science," says Evan Snyder, director of the Stem Cells and Regeneration Program at the Burnham Institute, in La Jolla, CA.

While animal models exist for many human diseases, they typically only incorporate certain aspects of the disease and can't capture the complexity of human biology. In addition, some disorders known to have a significant genetic component, such as autism, have proved difficult to model in animals.

To reprogram cells, scientists from Wisconsin and Japan independently engineered skin cells to express four different genes known to be expressed in the developing embryo. For reasons not yet clear to scientists, this treatment turns back the developmental clock. The resulting cells are pluripotent, meaning that they can develop into any type of cell in the body, and they can apparently divide indefinitely in their undifferentiated state. The first two published studies on the new technique reprogrammed cells from a skin-cell line, while a third study, published last month, generated stem cells from the skin biopsy of a healthy volunteer.

No one has yet generated cell lines from a patient, although scientists have been talking about doing so for years. Previously, the only way to make such models for complex genetic diseases was through human therapeutic cloning, also known as nuclear transfer, which is fraught with technical and ethical issues and has not yet been achieved. (See "Stem Cells Reborn" and "The Real Stem Cell Hope.") "Assuming that these procedures are as easy to do as it seems, it's definitely more tractable than nuclear transfer," says Snyder. His own lab is trying to generate such models, as is "probably everyone else you could call on your rolodex," he says.

To generate a disease-specific cell model, scientists would take some cells from a patient with a particular disease and revert them to an embryonic state. The cells would then be prodded to develop into the tissue type damaged in that disease, such as dopamine neurons in Parkinson's disease or blood cells in sickle-cell anemia. By comparing the differentiation process in cells derived from healthy and diseased people, scientists could observe how that disease unfolds at a cellular level. They could also use the cells to test drugs that might correct those biochemical abnormalities. "We want to use these cells to ask and answer questions that can't be asked and answered any other way," says M. William Lensch, a research scientist at the Harvard Stem Cell Institute and Children's Hospital Boston.

The relative simplicity of the approach--and the fact that it can be supported by federal funding--means that many more scientists are likely to attempt reprogramming than cloning. (In 2001, President Bush limited federal funding for embryonic stem-cell research to embryonic stem-cell lines already in existence.) According to Story Landis, chair of the Stem Cell Task Force at the National Institutes of Health, in Bethesda, MD, the funding agency has already announced two programs to fund reprogramming research and would welcome applications to derive cell lines from patients.

While no one has yet announced that he or she has derived a disease-specific cell model, George Daley's lab at Harvard may be in the lead. Last month, he and his team published a paper in Nature showing that they can reprogram cells from a skin biopsy from a healthy person, and they are already trying to repeat the feat with tissue from patients. Ultimately, they are interested in developing models of sickle-cell anemia and Fanconi anemia, a hereditary disease in which the bone marrow doesn't produce enough new cells to replenish the blood.

For example, patients with Fanconi anemia often suffer from skeletal problems, and their cells show an impaired ability to repair DNA. "We don't have any idea why kids with DNA repair defect would get a blood disease, and why they sometimes get these bone abnormalities," says Lensch, who works with Daley. But with stem-cell lines developed from a patient, "we could push the cells to develop into bone and blood, and try to learn about the links between the two."

Such models could also help resolve long-held debates about specific diseases, such as Alzheimer's. By differentiating reprogrammed cells from Alzheimer's patients into neurons and comparing them with neurons derived from healthy embryonic stem cells or with cells with mutations that mimic a rare, hereditary form of the disease, scientists will be able to determine how much of Alzheimer's is due to the environment versus genes, as well as how similar the sporadic form of the disease is to the hereditary form. (Most drugs on the market for Alzheimer's were developed using models that mimic the hereditary form of the disease and have shown limited efficacy in patients.) "This is a whole new world of investigation," says Lawrence Goldstein, a neuroscientist at the University of California, San Diego, whose lab is about to begin collecting skin cells from Alzheimer's patients.

Despite the excitement, Lensch and others caution against abandoning other embryonic stem-cell research, especially therapeutic cloning. "We're in the early stages of this research, where we're excited about the possibilities but still need to show it's both useful and representative of the disease," says Snyder. In addition, he says, embryonic stem cells and perhaps cloned stem cells will be needed as controls for future studies.

Scientists also say that it's too soon to tell how easy it will be to generate stem-cell lines from patients: the genetic variations that lead to the disease could also impact the reprogramming process. "With some genetic disease, I think it will be really difficult," says Lensch.

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Gene Therapy for Chronic Pain

By Jocelyn Rice

A new kind of gene therapy could bring relief to patients suffering from chronic pain while bypassing many of the debilitating side effects associated with traditional painkillers.

Researchers at Mount Sinai School of Medicine injected a virus carrying the gene for an endogenous opioid--a chemical naturally produced by the body that has the same effect as opiate painkillers such as morphine--directly into the spinal fluid of rats. The injections were targeted to regions of the spinal cord called the dorsal root ganglia, which act as a "pain gate" by intercepting pain signals from the body on their way to the brain. "You can stop pain transmission at the spinal level so that pain impulses never reach the brain," says project leader Andreas Beutler, an assistant professor of hematology and medical oncology at Mount Sinai.

The injection technique is equivalent to a spinal tap, a routine procedure that can be performed quickly at a patient's bedside without general anesthesia.

Because it targets the spinal cord directly, this technique limits the opiate-like substance, and hence any side effects, to a contained area. Normally, when opiate drugs are administered orally or by injection, their effects are spread throughout the body and brain, where they cause unwanted side effects such as constipation, nausea, sedation, and decreased mental acuity.

Side effects are a major hurdle in treating chronic pain, which costs the United States around $100 billion annually in treatment and lost wages. While opiate drugs can be very effective, the doses required to successfully control pain are often too high for the patient to tolerate.

"The side effects can be as bad as the pain," says Doris Cope, director of the University of Pittsburgh Medical Center's Pain Medicine Program. Achieving the benefits of opiate treatment without their accompanying side effects, Cope says, would be a "huge step forward."

Beutler hopes to do just that. "Our strategy was to harness the strength of opioids but target it to the pain gate, and thereby create pain relief without the side effects that you always get when you have systemic distribution of opioids," he says.

Several groups have previously attempted to administer gene therapy for pain through spinal injections, but they failed to achieve powerful, long-lasting pain relief. The new technique produced results that lasted as long as three months from a single injection, and unpublished follow-up studies suggest that the effect could persist for a year or more.

Beutler credits his team's success to the development of an improved virus for delivering the gene. The team uses a specially adapted version of adeno-associated virus, or AAV--a tiny virus whose genome is an unpaired strand of DNA. All the virus's own genes are removed, and the human endogenous opioid gene is inserted in their place. Beutler's team also mixed and matched components from various naturally occurring AAV strains and modified the genome into a double-stranded form. These tweaks likely allow the virus to infect nerve cells more easily and stick around longer.

Once the virus is injected into the spinal fluid and makes its way into the nerve cells of the pain gate, it uses the host cells' machinery to churn out the opioid protein--which then goes to work blocking pain signals on their way to the brain. Normally, the gene is rarely activated. But the version used for therapy has no such limitations because the gene carried by the AAV has been modified to continuously produce the opioid chemical.

Cope says that using endogenous opioids is inherently superior to injecting synthetic opiate drugs directly into the spinal fluid, an approach that requires the installation of a pump in order to deliver the drugs over a long time period. "It's kind of a holy grail," she says. "If the body's own system for pain control were activated by genetic expression, that would be superior to an artificial medication."

In Beutler's study, which was published this week in PNAS, rats were surgically modified to have a stronger than usual response to pressure on their paws, mimicking the effects of so-called neuropathic pain. The gene-therapy treatment effectively restored the rats to a normal level of pain sensitivity. The team also tested a nonopioid gene, which produced comparable pain relief through an entirely different mechanism. But while the opioid gene's effects will likely extend to humans, who respond to opiates the same way rats do, the nonopioid's effects may be rat specific.

The Stockholm-based company Diamyd Medical has been developing a different approach to gene therapy for chronic pain that also bypasses the side effects of standard pain treatment. The approach uses a deactivated version of herpes simplex virus (HSV). HSV can be administered straight through the skin as it naturally finds and infects peripheral nerves and travels to the spinal cord on its own. Darren Wolfe of Diamyd says that this method is superior to spinal injection because it's safer and easier, and it can be administered repeatedly.

Because of these considerations, the HSV method may be preferable for treating localized pain. However, when chronic pain involves multiple areas of the body--as it often does with, for example, metastasized cancers--going straight to the pain gate could work more efficiently.

While both of these methods have proved effective in animal models of pain, their efficacy in human patients remains to be shown. Diamyd recently applied to the FDA to begin phase I clinical trials, and Beutler estimates that his approach could be tested on humans in as few as three years.

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Gadis Australia Pasien Pertama Dunia yang Berubah Golongan Darah

Canberra (ANTARA News) - Seorang gadis remaja Australia --Demi-Lee Brennan-- menjadi pasien pertama yang mengubah golongan darahnya dan menerima sistem kekebalan dari donor organnya.

Brennan yang kini berusia 15 tahun menerima transplantasi organ hati pada saat usianya 9 tahun karena organ harinya tidak berfungsi.

"Hal itu adalah kesempatan kedua saya untuk dapat bertahan hidup," kata Brennan kepada media massa setempat ketika menceriterakan bagaimana tubuhnya berhasil menerima dan beradaptasi bedah transplantasi yang dapat dikatakan "Mukjizat" yang datang dari Tuhan. "Sungguh sulit dipercaya."

Golongan darah Brennan mengalami perubahan dari "O" negatif menjadi "O" positif pada saat ia sakit dan diberikan pengobatan untuk menghindari penolakan terhadap organ hati donor oleh sistem kekebalan tubuhnya.

Sel batang pembuluh darah hatinya yang baru memasuki sumsum tulang belakangnya yang mengubah seluruh sistem kekebalan tubuhnya, berarti si remaja Brennan tak lagi memerlukan obat-obatan anti penolakan tubuh.

Para dokter dari Rumah Sakit Anak Westmead di Sydney mengatakan mereka belum dapat memberikan keterangan kasus Brennan yang mengalami kesembuhan, seperti yang mereka sampaikan dalam majalah kedokteran, The New England Journal of Medicine.

"Terus terang kami belum menemukan penjelasan untuk hal itu," kata Michel Stormon seorang ahli hepatologi pediatri seperti dikutip Reuters.

Sturat Dorrney, mantan kepala bagian unit transplantasi di rumah sakit itu mengatakan, kasus Brennan dapat membuka jalan bagi terapi transplantasi organ, karena biasanya sistem kekebalan tubuh pasien penerima menyerang transplantasi jaringan di donor.

"Kini kami harus kembali mengkaji ulang semua tahapan yang terjadi pada Demi-Lee dan melihat mengapa hal itu dapat terjadi dan kalau-kalau dapat melakukan pengulangan kembali," kata Dorney.

"Kami berpikir hal itu mungkin karena kami menggunakan organ hati dari seseorang yang usianya masih muda dan Demi-Lee memiliki sel darah putih dalam jumlah rendah mungkin karena dua faktor itulahyang menjadi alasan," katanya kepada harian Daily Telegraph.

Penolakan tubuh umumnya ditangani dengan kombinasi obat-obatan walaupun penolakan kronik tidak terjadi dua arah (bolak-balik).

Hanya tujuh dalam 10 operasi transplantasi di Australia yang berhasil setelah lima tahun berselang yang dikarenakan oleh penolakan tubuh di pasien. (*)

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Pil KB Cegah Kanker Indung Telur

Beijing (ANTARA News) - Pil KB dapat berbuat lebih dari sekedar mencegah kehamilan, pil tersebut juga dapat melindungi perempuan dari kanker indung telur selama lebih dari 30 tahun atau lebih setelah mereka mengkonsumsinya, demikian hasil penelitian di Inggris yang disiarkan pekan ini.

Makin lama perempuan mengkonsumsi pil itu, makin rendah resiko mereka terserang penyakit itu, yang lebih umum menyerang setelah perempuan berusia 50 tahun, tulis para peneliti tersebut di jurnal "Lancet".

Perempuan yang mengkonsumsi pil itu selama 15 tahun mengurangi resiko mereka terserang penyakit tersebut separuhnya, kata para peneliti itu.

Di seluruh dunia, pil tersebut sudah membantu 200.000 perempuan dari serangan kanker indung telur dan telah mencegah 100.000 kematian akibat penyakit itu, kata Valerie Beral dari University of Oxford dan rekannya dalam laporan mereka.

"Ketika anda berusia 60 tahun, ada manfaatnya jika anda mengkonsumsinya lima tahun atau 10 tahun saat anda berusia 20-an tahun," kata Beral dalam suatu wawancara telefon. "Makin lama anda mengkonsumsinya, makin baik bagi anda tatkala resiko kanker indung telur tinggi."

Sebanyak 300 juta perempuan telah menggunakan pil KB sejak pil itu diperkenalkan pada awal 1060-an. Ratusan kajian telah meneliti keamanannya, sebagian menunjukkan manfaat dan yang lain memperlihatkan peningkatan resiko kanker payudara dan kanker leher rahim.

Beral dan rekannya mengatakan penelitian mereka, yang menganalisis 45 kajian kanker indung telur di 21 negara, memperlihatkan bahwa manfaat pil tersebut lebih besar dari resikonya. Kanker

Kanker indung telur sangat mematikan karena perempuan seringkali mengalami gejala ringan atau tak menghadapi gejala sama sekali hingga penyakit itu telah berkembang.

Resiko kanker payudara, yang juga mengakibatkan stroke dan pembekuan darah, jauh lebih kecil dan hanya ada saat perempuan mengkonsumsi pil tersebut dan tak lama setelah mereka berhenti, kata Beral seperti dikutip Xinhuanet.

Mengkonsumsi pil itu selama 10 tahun mengurangi resiko kanker indung telur sebelum usia 75 tahun dari 12 per 1.000 perempuan jadi 8 per 1.000. Pil tersebut juga mengurangi resiko kematian akibat penyakit itu dari 7 per 1.000 perempuan jadi 5 per 1.000 sebelum usia 75 tahun, demikian temuan studi tersebut.

Lebih dari 100 juta perempuan sekarang mengkonsumsi pil tersebut, jadi akhirnya itu akan mencegah lebih dari 30.000 kasus kanker indung telur setiap tahun selama beberapa dasawarsa ke depan, tulis para peneliti tersebut. (*)

Copyright © 2008 ANTARA

Pengobatan Kanker Juga Bantu Obati Osteoporosis

Washington (ANTARA News) - Obat yang digunakan untuk mengobati kanker tulang sumsum juga dapat membantu mengobati osteoporosis dengan merangsang sel-sel tungkai, kata beberapa peneliti AS, Jumat.

Mereka mendapati bahwa Velcade, yang dibuat oleh Millenium Pharmaceuticals Inc (MLNM.O) untuk mengobati tumor ganda di sumsum tulang, mengaktifkan sel-sel tungkai yang berubah menjadi tulang.

Ujicoba terhadap tikus memperlihatkan membantu mengaktifkan jaringan tulang dan mungkin merupakan pengobatan yang berpotensi bagi osteoporosis, kata satu tim di Massachusetts General Hospital dan Harvard Stem Cell Institute di "Journal of Clinical Investigation".

Ahli sel tungkai di Harvard Dr. David Scadden mengatakan, para ilmuwan telah berharap menemukan cara untuk menggunakan obat guna merangsang sel-sel tungkai, yang merupakan sel pengendali tubuh.

"Terapi sel tungkai seringkali dikira sebagai tindakan memasukkan sel baru ke dalam tubuh, tapi studi ini menunjukkan bahwa pengobatan dapat mengubah sel-sel tungkai yang ada yang terdapat di jaringan tubuh dan bertindak sebagai obat pengaktifan untuk meningkatkan mekanisme perbaikan sendiri tubuh," kata Scadden dalam suatu pernyataan.

"Obat yang mengarahkan sel-sel tak matang untuk menjadi sejenis sel khusus, seperti dalam studi ini, dapat berpotensi sangat bermanfaat," katanya seperti dikutip Reuters.

Velcade, yang secara generika dikenal sebagai "bortezamib", merangsang sel-sel tungkai "mesenchymal", demikian temuan para peneliti tersebut. Sel-sel itu berkembang menjadi zat pembangun-tulang "osteoblast" dan beberapa jenis sel lain termasuk "cartilage", lemak, kulit dan otot.

Ujicoba pada tikus memperlihatkan obat tersebut meningkatkan kegiatan "osteoblast", dan ketika digunakan pada tikus yang menderita osteoporosis, obat itu secara mencolok meningkatkan kepadatan dan susunan tulang.

"Jika paradigma yang terlihat dalam studi ini terbukti benar bagi jaringan lain, kita mungkin memiliki pilihan untuk memperbaiki dan mengaktifkan kembali berbagai tempat yang terpengaruh oleh cedera atau penyakit dengan menggunakan obat --itu akan sangat menggairahkan," kata Scadden. (*)

Copyright © 2008 ANTARA

Mixing Up the Immune System

By Anna Davison

By performing bone-marrow transplants along with kidney transplants, doctors in Boston were better able to trick recipients' immune systems into accepting the new organs as if they were their own.

Even though the patients received donor kidneys that weren't a good match, most of them were successfully weaned off of immune-suppressing drugs about a year after their transplants. Normally, patients have to take the drugs, which can have serious side effects, for the rest of their lives.

"It's groundbreaking work," says John C. Magee, director of the Kidney Transplant Program at the University of Michigan, who was not involved in the study. "They've shown that you can reeducate the immune system."

The technique could be applied to other kinds of transplants and used in the treatment of autoimmune diseases, says Megan Sykes, one of many researchers who carried out the work at Massachusetts General Hospital. Sykes is the associate director of the hospital's Transplantation Biology Research Center.

The team has been working for about 20 years to outsmart the immune system by inducing tolerance to a donor organ. In this study, reported in this week's issue of the New England Journal of Medicine, the scientists transplanted bone marrow along with a mismatched kidney, giving patients a kind of hybrid immune system that blended elements of both the donor and the recipient.

Four out of five patients who received bone-marrow transplants in conjunction with kidney transplants didn't need long-term treatment with immune-suppressing drugs. The technique was not successful for the fifth patient, however: his body rejected the donor kidney. He was given a second--and successful--transplant according to conventional protocol.

Doctors try to match people with similar versions of the genes that play a crucial role in immune reactions to foreign tissue. This genetic region is known as the human leucocyte antigen (HLA) complex. But finding a good match isn't always possible, so doctors often use a mismatched kidney and put the patient on immunosuppressive drugs to reduce the risk of rejection. The patients in the study, whose ages ranged from 22 to 46, were all suffering from advanced kidney disease and were unable to find living donors who were a very good tissue match. They received kidneys from family members who were HLA mismatched.

Before the surgery, the transplant team gave the patients drugs to deplete their bone marrow and suppress their immune response. After receiving new kidneys and then an intravenous infusion of bone marrow from their donors, the patients were kept in a relatively sterile environment to reduce their chance of infection, and to allow the bone marrow to regenerate and produce new immune cells that wouldn't attack the donor kidney.

In the months after their transplants, the patients in the study were treated with immunosuppressive drugs, but four out of five of them were able to discontinue those drugs between 9 and 14 months after surgery, and their new kidneys have been functioning well in the years since.

"I think it's quite exciting," Magee says. "It shows what's possible."

The researchers' approach could make transplants more feasible for people whose immune systems are already compromised by conditions like HIV, according to Yasir Qazi, medical director of the kidney and pancreas transplant program at the University of Southern California. (Qazi was not involved in the work.) Sykes says that the approach could potentially be used to treat autoimmune diseases such as type 1 diabetes. "It could have huge benefits," she says.

Although immunosuppressive drugs have revolutionized transplant medicine, they can increase the risk of cancer and heart disease. "Immunosuppression is great, because it makes kidneys work, but it's bad because it has lots of side effects," Magee says. "Some people say that in many ways, you're trading one disease for another. You still have to take lots of medicine and see a doctor."

The protocol developed by Sykes and her colleagues initially requires heavier drug treatment than that required with the standard kidney-transplant procedure, to allow the recipient's body to accept donated bone marrow as well as a donated kidney. But, she points out, the patient is only on the drugs for a limited time.

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