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.

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

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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.

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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

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

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

from here

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.

from here

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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Synthesizing a Genome from Scratch

By Emily Singer

In a technical tour de force, scientists at the J. Craig Venter Institute, in Rockville, MD, have synthesized the genome of the bacterium Mycoplasma genitalium entirely from scratch. The feat is a stepping stone in creating precisely engineered microbial machines capable of generating biofuels and performing other useful functions.

"It really is groundbreaking that you can synthetically build a genome for a bacterium," says Chris Voigt, a synthetic biologist at the University of California, San Francisco, who was not involved in the project. "It's bigger by orders of magnitude than what's been done before."

Biologists creating genetically engineered organisms now routinely order pieces of DNA that are 10,000 to 20,000 base pairs long--big enough to incorporate the genes for a single metabolic pathway. That allows researchers to engineer microbes that can perform specific tasks, but the ability to synthesize entire genomes could grant a whole new level of control over biological design. (See "Tumor-KillingBacteria.")

In the new study, scientists ordered 101 DNA fragments, encompassing the entire Mycoplasma genome, from commercial DNA synthesis companies. These fragments were designed so that each overlapped its neighboring sequence by a small amount; these overlapping stretches stick together, thanks to the chemical properties of DNA. Researchers then bound the fragments piece by piece, eventually generating the full 582,970 base pair Mycoplasma sequence. The findings were published Thursday in the online edition of Science.

"We consider this a second and significant step in a three-step process of our attempt to create the first synthetic organism," says Craig Venter, president of the Venter Institute. Venter and his colleagues ultimately want to create a minimal genome--one with the least number of genes needed to sustain life. Pinpointing the minimal genome will both shed light on key cellular processes and provide a base for designing sophisticated synthetic organisms. "We ultimately want to design cells that could function in a robust fashion to make unique biofuels," says Venter.

The researchers' next step will be to show that the synthetic genome functions as it should. "We have the whole genome assembled in a tube, but we need to transplant it into the cell of a different species to show that it can reboot the cell," says Hamilton Smith, a Nobel laureate who oversaw the project at the Venter Institute. Last year, Smith's group transplanted the genome of one species of Mycoplasma into another, demonstrating that this type of transplant is possible. (See "Transplanting a Genome.")

While the synthesis of a genome might be impressive from a scientific perspective, it is not yet a practical way to engineer microbes to make biofuels. Instead, several companies, including Synthetic Genomics, a biotech company founded by Venter to engineer microbes for energy, are using more traditional metabolic engineering techniques to generate fuel-producing bacteria. (See "Building Better Biofuels.") "What we're doing with synthetic chromosomes will be the design process for the future," says Venter.

Others in the field are excited about that prospect. "Being able to synthesize genomes opens up a new world," says Voigt. "You can build things on the scale of the genome." For example, he says, scientists are now engineering bacteria to perform different steps in the conversion of biomass into ethanol--one strain to break down the biomass, another to make ethanol. But ideally, scientists could put those processes together to create one organism that could eat biomass and spit out fuel. (See "The Price of Biofuels.") "That would require genome-scale design," Voigt says.

He likens the current project, which required multiple steps to glue the fragments together, to the last computers designed before automated manufacturing and microfabrication techniques were introduced. Similar advances are needed for more ambitious genome-synthesis projects. "We still need to develop 'one step' genome construction methods in order to reduce the costs and turn time of genome construction," says Drew Endy, a synthetic biologist at MIT.

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Growth Hormone: Fountain of Youth or Early Killer?

Growth hormone holds a conflicted status in the world of life extension. Some believe it turns back the clock, with evidence from humans suggesting that hormone treatment reduces fat and boosts muscle. But animal studies show the opposite: mice without growth hormone live significantly longer and are protected against cancer, one of the most deadly diseases of aging.

Valter Longo, a scientist at the University of Southern California, in Los Angeles, hopes to untangle this conundrum by studying an unusual group of people in Ecuador: those with a genetic mutation that renders them insensitive to growth hormone. "They are the largest population in the world that is growth-hormone deficient," says Longo. Studies of the group could provide a valuable window into whether growth-hormone depletion could, in fact, be used to extend longevity. The study could also shed light on how to develop drugs against the diseases of aging without introducing unintended side effects.

Growth hormone is a crucial protein produced by the pituitary that directs growth and cell division. People who lack the hormone or the ability to respond to it are extremely short, while those whose hormone levels dip in middle age, such as after damage to the pituitary, have an increased risk of cardiovascular disease. In mice, however, deficiency of the hormone seems to be beneficial. "In the mouse, the effect is major and striking," says Andrzej Bartke, a biologist at Southern Illinois University in Springfield, who is not involved in the project. "They seem protected from cancer and appear to have delayed aging by various measures. But there is almost no evidence that growth-hormone deficiency would extend life in humans."

The group Longo plans to study lives in the rural Loja province in the southern portion of Ecuador. These isolated mountain communities have a high rate of an otherwise rare condition known as Laron dwarfism. People with the condition lack a functioning version of the receptor that binds to growth hormone.They are small and obese, but little data exists on their longevity.

Children with the condition seem more susceptible to pneumonia and diarrhea, common scourges of poor rural communities, and they die at twice the rate of their unaffected siblings. Those who survive to adulthood typically have high cholesterol and triglycerides, risk factors for heart disease. Some die of heart disease, an uncommon occurrence in rural Ecuador, but preliminary reports suggest that Laron dwarves are protected from artherosclerosis, arterial hardening that can lead to heart attack. Adding to the puzzle is anecdotal evidence suggesting that they don't get cancer or type 2 diabetes. "It's a balance: if you turn down risk of cancer, you might turn up risk of heart disease," says Steven N. Austad, a biologist at the University of Texas Health Sciences Center, in San Antonio, who is not involved in the project.

To try to determine how the hormone impacts diseases of aging, Longo plans to compare rates of cancer, heart disease, and diabetes, as well as longevity data, in those with one or two copies of the gene and their unaffected relatives. Those who carry one functioning copy of the growth-hormone receptor appear normal; if they are protected against cancer and do not suffer from obesity and heart disease, they may represent a happy medium of growth-hormone exposure. So far, the scientist has genotyped about 300 people--100 with two copies of the mutation, and 200 relatives and controls.

"If blocking growth hormone is associated with an improvement or decreased incidence of cancer, there are tools that we have as physicians to address that," says Pinchas Cohen, a pediatric endocrinologist at the University of California, Los Angeles, who has treated children with Laron dwarfism. Drugs that inhibit secretion of the hormone or block its action already exist. And drug companies are now testing blockers of a molecule that acts downstream of growth hormone, called IGF-1, as a treatment for cancer. If IGF-1 works, it's not yet clear if the most effective intervention will be as a preventative measure, perhaps targeting families with a history of cancer, or if growth-hormone or IGF-1 depletion could be used as a cancer treatment.

Not everyone is optimistic that limiting growth hormone in people will have the same effects it does in mice. "Growth hormone in humans is different than that of most mammals," says Austad. It has a broader mechanism of action and appears to have evolved rapidly since we diverged from other mammalian ancestors. "No one knows why," says Austad, "but something has happened to make growth hormone very different in humans."

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Treating Muscular Dystrophy with Stem Cells

Researchers at the University of Texas Southwestern Medical Center (UT Southwestern) have used embryonic stem cells from mice to grow muscle cells. These same cells, injected into mice with a mild form of muscular dystrophy, formed healthy, functional muscle fibers at the site of deteriorating tissue. Scientists say that the research, while still in its early stages, could eventually lead to a cell-based therapy for patients with muscular dystrophy and other muscle-related diseases. The research was recently published in the online edition of Nature Medicine.

According to the Muscular Dystrophy Association, about 250,000 people in the United States have some form of the disease. The most well known, Duchenne muscular dystrophy, is caused by a genetic mutation that disrupts the formation of dystrophin, an important protein involved in the formation of muscle cells. In the absence of dystrophin, muscles are unable to regenerate, and they gradually weaken and waste away. Eventually, the deteriorated area is taken over by fat and connective tissue.

Rita Perlingeiro, assistant professor of developmental biology at UT Southwestern, says that embryonic stem cells may be the key to reversing muscular dystrophy's debilitating effects. The advantage lies in the cells' pluripotency--the ability to transform into any mature cell, be it bone, muscle, or cartilage. However, many researchers have found it difficult to direct every stem cell in a culture to form a specific type of cell. In lab experiments, scientists often end up with a mixture of cells that, when injected into an animal, form large clusters resembling a tumor.

So Perlingeiro and her team set two main goals: to find the right set of cues to convert embryonic stem cells into muscle cells, and to look for ways to isolate muscle cells from the rest of the culture medium, in order to inject a dose of pure muscle cells into a mouse model.

In normal embryologic development, stem cells turn into various tissue and bone, depending on a combination of molecular and genetic signals. In the case of muscle cells, past research has shown that the gene Pax-3 is essential in pointing stem cells down the path of muscle formation. With this knowledge, Perlingeiro and her team grew mouse-derived embryonic stem cells in a culture dish, then genetically manipulated the solution to overexpress Pax-3. They found that, compared with mixtures without Pax-3, a significant number of stem cells exposed to the activated gene formed muscle cells.

However, not all of the cells turned into muscle, and when the team injected the solution into a mouse with a mild form of muscular dystrophy, the mixture caused tumors to form. The team then focused on developing an identification process that would make muscle cells stand out from the rest of the solution. Once again, Perlingeiro looked to basic developmental research and found that, during normal muscle formation in the embryo, stem cells that become very early versions of muscle cells display certain surface molecules, or markers. The team repeated the first phase of its experiment, exposing embryonic stem cells to Pax-3, and looked for the telltale markers indicating muscle cells. The researchers then isolated these cells, creating a solution that consisted solely of muscle cells.

In preparation for injecting the new solution into a mouse model, the team first injected cardiotoxin into the mouse's leg. The effect inhibited the production of dystrophin, causing a weakening of the muscle--a condition resembling muscular dystrophy. Perlingeiro and her colleagues then injected the mouse with the muscle-cell solution. The team then took muscle biopsies and, after immuno-staining, found that, compared with mice that did not receive the solution, treated mice exhibited more dystrophin, indicating healthy muscle regeneration.

To confirm their results, the researchers ran both groups of mice on a treadmill; they found that the mice that received the solution outlasted the group that did not. Perlingeiro went a step further: after sacrificing both animal groups, she and her colleagues extracted every leg muscle, treated or untreated. They then placed each muscle in a bath and tested its strength by exposing it to an electrical impulse. The team found that the stronger contractions came from the muscles treated with the stem-cell-derived solution.

Perlingeiro says that the study's results are encouraging, as she envisions one day providing stem-cell-based therapy for people with muscular dystrophy and other muscle-related diseases. However, there will have to be more follow-up studies before the technique can be applied to humans.

"I have a long to-do list," says Perlingeiro. "We'd like to use the same technique on human embryonic stem cells."

Recently, researchers were able to turn human skin cells into embryonic stem cells, a technique that bypasses the thorny issues currently surrounding use of embryonic stem cells. Perlingeiro says that combining this technique with her muscle-deriving method may one day yield effective, efficient treatment of diseases such as muscular dystrophy.

"If we can reprogram skin cells to become pluripotent, and use Pax-3 to make muscle, then we would be able to make cells from the patient, and we wouldn't face ethical issues or problems of rejection," says Perlingeiro.

Paul Muhlrad, a research program coordinator for the Muscular Dystrophy Association, says that the study's results are a promising step toward effective treatment for muscle-related diseases. "These researchers present a nice proof of principle that embryonic stem cells can be turned into muscle-producing cells in the laboratory and used to deliver healthy muscle to people with Duchenne muscular dystrophy," says Muhlrad. "Of course, these experiments were done with mice. We've yet to see whether they will work in humans, but this study offers us much hope."

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Mixing Mammals

By outfitting mice with a chunk of DNA that directs wing development in bats, scientists have created rodents with abnormally long forelimbs, mimicking one of the steps in the evolution of the bat wing. Their work gives weight to the idea that variations in how genes are controlled, and not just mutations in the coding regions of genes, are a driving force in evolution.

The slightly longer forelimbs of the transgenic mice "make them more batlike," says Nipam Patel, a professor of molecular and cell biology and integrative biology at the University of California, Berkeley, who was not involved in the work. "It seems like a subtle difference, but evolution works by these subtle differences."

The researchers focused on a gene, Prx1, that plays a part in the elongation of limb bones in mammals. The gene's expression is regulated by another sequence of DNA, called a Prx1 enhancer. To investigate how the enhancer shapes limb development, Richard Behringer, a professor of molecular genetics at the University of Texas MD Anderson Cancer Center, and his colleagues around the country put the bat version of the Prx1 enhancer into mice so that it controlled the mouse Prx1 gene. These transgenic animals developed forelimbs that were on average 6 percent longer than normal by the time they were born. It was a significant difference, although "the mice look like mice," Behringer says. "They're not going to fly out of the cage." The researchers report their work in the latest issue of Genes and Development.

To have any chance of flying, mice would have to develop very different forelimbs, like those of bats, which are longer and have membranes stretched between the bones. Behringer says that he'd like to try replacing the limb enhancers in mice with those from other animals, such as whales or wallabies.

Charles Darwin contemplated the evolution of different kinds of limbs in On the Origin of Species. Starting with a basic limb pattern, "successive slight modifications," he wrote, eventually produce the various mammal limbs we see today: human hands, bat wings, whale fins.

"We think what we've done is made one of those slight modifications," Behringer says. "Maybe during evolution you'd have a lot of those and the limb would get a lot longer, and maybe some of the tissue would be retained between digits, ultimately leading to the structures that would allow a bat to fly."

"It's a very nice demonstration of something that people have been suspecting now for some time: that regulatory sequences rather than changes in protein sequences sort of drive evolution," says Susan Mackem, who heads the Developmental Biology Unit at the National Cancer Institute's Center for Cancer Research. Mackem was not involved in Behringer's research.

Behringer's team also found something unexpected. When the researchers created mutant mice that lacked the mouse Prx1 enhancer, the animals developed forelegs of a normal length. That suggests that more than one enhancer controls the expression of the Prx-1 gene in mice, ensuring what Behringer calls a "regulatory redundancy."

"As long as there is one copy to do the work, the other copy can be creative," says Ann Burke, an associate professor of biology at Wesleyan University.

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Gene Therapy for Alcoholics

Researchers in Chile have succeeded in keeping the drinking habits of alcoholic rats in check using gene therapy. The treatment mimics a natural mutation common in East Asian people, which lowers their tolerance to alcohol, making them less likely to become alcoholics.

According to the National Institutes of Health, 17.6 million people abuse alcohol or are alcohol dependent in the United States alone. If the gene-therapy technique could be applied to humans, scientists say that it may be a valuable addition to the drugs and behavioral approaches currently used to treat alcoholism.

The gene therapy works in a similar way to a drug currently used to treat alcoholics, which is effective but unpopular with patients, many of whom stop taking it.

"It's great when innovative approaches are being used for treatment, because we need them," says George Koob, codirector of the Pearson Center for Alcoholism and Addiction Research, at the Scripps Research Institute. He was not involved in the work in Chile.

The gene therapy, described in the latest issue of the journal Alcohol: Clinical and Experimental Research, curbed the activity in the liver of an enzyme--aldehyde dehydrogenase--that plays a major role in metabolizing alcohol. Nearly a third of East Asians have a natural genetic mutation that has the same effect, so when they drink, their faces turn red, their hearts pound, and they feel sick--all good incentives to go easy on alcohol.

The gene therapy tested by Yedy Israel, a professor of pharmacological and toxicological chemistry at the University of Chile, and his colleagues triggers the same unpleasant response to alcohol in rats.

"It's a new way of doing an old thing," Koob says. "I think it's very clever and very interesting."

The researchers in Chile started with rats bred for their alcoholic tendencies and offered them unlimited quantities of diluted ethanol--the equivalent of higher-alcohol premium beer--for two months to make them even more dependent. The researchers then cut off the animals' access to alcohol and injected some of them with a virus containing a gene that inhibits aldehyde dehydrogenase.

Three days later, the researchers implemented a month of daily "happy hours," letting the rats drink as much as they wanted. In an hour, each of the animals put away the equivalent, in human terms, of about seven premium beers--10 times more alcohol than what was put away by alcoholic animals that hadn't been through the two-month dependency regimen.

During the first happy hour, rats that were given gene therapy "didn't realize they were going to feel bad, and they drank a tremendous amount," Israel says. Afterward, "the animals clearly didn't look comfortable." Those rats then markedly reduced their alcohol consumption on subsequent days. Over the course of the happy hours, they drank half as much, on average, as the untreated animals. The effect lasted throughout the monthlong study.

Israel and his colleagues are now working on ways of delivering gene therapies that last for years or even a lifetime, in the hope of developing long-lasting treatments for alcoholism. Most of the medications available now need to be taken at least once a day, and many alcoholics don't comply with the routine. A longer-lasting drug is likely to be more successful, Israel says.

Two of the three existing drug treatments approved for alcoholism by the Food and Drug Administration--naltrexone and acamprosate--limit the craving for alcohol. The other treatment--disulfiram--works in a similar way to Israel's gene therapy: by making patients sick if they drink. The trace of alcohol in mouthwash is enough to trigger a reaction, and most alcoholics "really dislike this medication," says Carolyn Drazinic, an assistant professor in the Department of Psychiatry and the Department of Genetics and Developmental Biology at the University of Connecticut. She was not involved in the gene-therapy research.

"All of these drugs," Israel says, "really require patients' compliance with their medication, which is rare."

Drazinic says, though, that a lifelong treatment that makes someone sick after a whisper of alcohol might not have too many takers. "There may be a lot of patients who would refuse something like this, if they've ever experienced a disulfiram reaction," she says. Drazinic believes that a more popular option might be a treatment that doesn't last a lifetime, but long enough not to be a daily hassle.

That, Koob says, would be better than "someone sitting there with a baseball bat telling you to take your Antabuse [the trade name for disulfiram] with your Wheaties."

Robert Swift, a professor of psychiatry and human behavior and the associate director of

Brown University's Center for Alcohol and Addiction Studies, says that the gene-therapy approach "is a very interesting technique, but it's not ready for prime time."

"There are a lot of medications that reduce drinking in animals but may not be as effective in humans," he says. "The question is, can you really make enough difference in the enzymes that humans will reduce their drinking?"

Gene therapy is risky, and if it's ever used to treat alcoholism in humans, it should be a last-ditch option for hardcore alcoholics, Swift says. However, those patients are often suffering from liver damage, and "if someone's got damaged liver cells, you've got a greater risk of complications from genetic treatment."

Israel's gene-therapy approach is "perfectly logical," says Raymond White, director of the University of California, San Francisco's Ernest Gallo Clinic and Research Center, where scientists study the biological basis of alcohol and substance abuse. But White adds that he'd be quite surprised "if this became a real therapy."

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DNA Deletion Linked to Autism

A specific structural variation on chromosome 16 dramatically boosts the risk of autism, according to a study published today in the New England Journal of Medicine. The finding--one of the most significant to date--permits the development of new diagnostic tests to identify children at risk, and could ultimately point to specific biochemical pathways to target in drug development.

"This is one of the single largest [influences] and most frequent genetic causes for autism identified so far," says Bai-Lin Wu,director of the Genetics Diagnostic Laboratory at Children's Hospital Boston and one of the senior authors on the study.

Autism spectrum disorder--or autism, as it is commonly called--refers to a group of developmental disabilities with wide-ranging language, social, and behavioral symptoms. The disorder is known to have a strong genetic influence, with up to 90 percent of cases thought to have a genetic component. However, because the disorder is linked to a combination of genetic variations, each playing a minor role, identifying specific genetic triggers has been difficult. Now new microarray technologies, which allow scientists to screen a million or more genetic variations in thousands of patients, are enabling the much larger studies needed to pinpoint these triggers.

In the new paper, scientists say that they used microarrays to scour the DNA of more than 2,000 individuals with autism. They found that deletion or duplication of approximately 500 of the same DNA letters on chromosome 16 was strongly linked to autism, accounting for about one percent of cases. "While that doesn't sound like a huge number, the fact that these people carry the identical spontaneous deletion or duplication would be incredibly unlikely to happen by chance," says Mark Daly, a geneticist at Massachusetts General Hospital's (MGH) Center for Human Genetic Research, in Boston, and at the Whitehead Institute, in Cambridge, and one of the study's senior authors.

The results were independently identified by three different groups--at MGH; Children's Hospital Boston; and deCODE Genetics, in Iceland--that are studying three different populations, giving added weight to the work.

The findings build on previous reports that autism is linked to genetic deletions or duplications that arise spontaneously, rather than being passed down through generations. In almost all cases, parents of the affected people did not carry the chromosome 16 variation.

One of the most immediate clinical benefits of the research will be the development of inexpensive diagnostic tests. "Because the variation occurs so frequently, you could directly test for the presence or absence of a duplication or deletion as part of standardized genetic testing for autism," says James Gusella, a neurogeneticist at Harvard Medical School, in Boston, who participated in the research. For example, children who show developmental delays but are too young to undergo clinical autism testing could be screened for this variation, allowing parents and doctors to prescribe intervention for those who test positive. "We will be able to find at-risk children early on so that language and behavior problems can be treated much earlier," says Yiping Shen, director of research and development at Children's Hospital's Genetics Diagnostic Laboratory, who was also involved in the work.

Such testing could also predict if parents with one autistic child are at greater risk of having another; if their child's autism is linked to a spontaneous variation, they are at no greater risk than the general population. Researchers at Children's Hospital, which provides genetic testing to families, are already developing a clinical diagnostic test.

Scientists are also trying to pinpoint the specific gene or genes within this section of DNA that underlie the increased risk. Daly and his collaborators plan to sequence this region of the genome in another group of people with autism, in search of single-letter mutations that might disrupt the function of specific genes. "Genetics provides us with the only opportunity to gain insight into the biological mechanisms that underlie autism," says Daly. "We can look at individual gene discovery as a small first step in the overall path to develop treatments."

Previous studies have identified autism risk genes. However, these studies have focused on people with genetic disorders that often co-occur with autism, such as Fragile-X syndrome, complicating the role those genes play in the disorder. "Up until now, we haven't had the capacity to look at a single gene that is associated with pure autism," says Gusella.

The findings could point to additional spots in the human genome to search for autism risk genes. The variation on chromosome 16 lies within a genetic "hot spot," an area that is predisposed to undergoing structural duplications due to the architecture of the DNA, says Evan Eichler, a geneticist at the University of Washington in Seattle, who wrote an editorial accompanying the paper. "Every time we produce gametes, there's a finite probability of this region to duplicate," he says. In addition, the region has a high concentration of genes that are rapidly evolving in humans. While the significance of that finding is not yet clear, it may explain autism's status as a relatively young disease.

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Killing Skin-Cancer Stem Cells

Harvard Medical School researchers have identified a class of cells that initiates skin-cancer melanomas; they are also developing a therapy that specifically targets these cells. In a major study, the researchers characterized these cells and linked them to disease progression in humans. They also demonstrated that an antibody targeting these cells slows tumor growth in mice. The work may lead to new treatments for resistant melanoma. It also has broader implications for cancer biology.

There is a growing consensus amongst cancer biologists that not all cancer cells are equal. There is a hierarchy of cells inside a tumor, and only a few cells, called cancer stem cells, are capable of generating new tumors. Such tumor-initiating cells have been identified in many cancers, including those of the colon, brain, and breast. These cells are also thought to play an important role in chemotherapy resistance and cancer recurrence.

Previously, researchers had connected the presence of cancer stem cells with breast-cancer patient outcomes. Now the Harvard team has demonstrated a second important connection between cancer stem cells and clinical impacts, linking the presence of such cells with the speed at which the disease progresses in humans.

"We've defined for the first time a direct link between cancer stem cells and cancer progression," says Markus Frank, an assistant professor at Harvard Medical School, who led the melanoma research.

This research grew out of Frank's study of a protein made by some melanomas that confers resistance to chemotherapy. In a paper published today in the journal Nature, Frank and his colleagues at Harvard Medical School and Brigham and Women's Hospital, in Boston, report that human melanoma cells that make this protein can be characterized as cancer stem cells because they generate tumors when implanted in mice. Examining melanoma biopsies, they found that tumors expressing this protein were more aggressive.

Frank's group also demonstrated that an antibody specifically targeting the melanoma stem-cell protein slowed tumor growth in mice. Many other researchers are working on therapies that attack cancer stem cells, but Frank believes that his group is the first to develop such an antibody.

"Most current therapies target the bulk cells of the tumor," he says. "Resistant stem cells are left behind," allowing the tumor to come back after therapy seems to be progressing. Frank and other researchers hope that therapies that specifically target cancer stem cells can completely eradicate tumors.

Robert Weinberg, a founding member of the Whitehead Institute for Biomedical Research, in Cambridge, MA, and director of the Ludwig Center for Molecular Oncology at MIT, agrees that the Harvard work adds to the growing evidence of cancer stem cells' importance. "We don't really understand how tumors renew themselves, or how to treat many tumors," he says. Some researchers remain unconvinced, Weinberg says, but he and many others think that cancer stem cells may hold the answers to these questions. Cancer stem cells are "going to be very important," he predicts. Slowly but surely, he believes, the evidence is building.

Frank says that much remains to be learned about the newly identified melanoma stem cells. It's not clear, for example, whether the protein that the Harvard researchers have been focusing on causes the cells to act as cancer stem cells, or whether this protein is simply a marker for these cells. Further studies of their gene-expression patterns will tell the researchers more about what makes them different from normal melanoma cells. In the meantime, the Harvard researchers will continue to develop their antibody in hopes of taking it to human trials.

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Indonesia Kaya Mikroba Penghasil Antibiotik

Alam tropis Indonesia menyimpan banyak mikroba yang sifatnya berbeda dengan mikroba yang berasal dari daerah subtropis dan daerah kutub. Karenanya, Indonesia sangat potensialditemukan mikroba penghasil antibiotik. Saat ini, Indonesia memiliki lebih kurang 30.000 spesies tumbuhan dan 940 spesies diantaranya termasuk tumbuhan berkhasiat dan baru 180 spesies yang sudah dimanfaatkan oleh industri jamu tradisional.

Demikian dikatakan Elin Yulinah Sukandar, peraih Habibie Award tahun 2007 dari Sekolah Farmasi Institut Teknologi Bandung (ITB) kepada Harian Terbit, Senin [14/1]. "Standardisasi bahan baku obat dan obat jadi merupakan pembuktian efek farmakologi secara praklinis dan klinis serta informasi keamanan obat merupakan tantangan agar obat herbal lebih diterima oleh masyarakat," ujarnya.

Menurutnya, untuk memperoleh obat yang khasiatnya konsisten bahan obat perlu distandardisasi. Dalam pengembangannya, bahan obat harus melewati uji praklinik dan uji klinik. Bahan bakunya juga harus distandardisasi. Uji praklinik, katanya, dapat dilakukan secara in vitro melalui sistem reaksi enzimatik menggunakan kultur sel atau jaringan, uji terhadap mikroba/parasit pada medium perbenihan menggunakan organ terisolasi atau pada hewan percobaan secara in vivo.

Uji praklinik, tambah Elin, merupakan persyaratan yang harus dilakukan untuk menjamin khasiat dan keamanan suatu obat sebelum memasuki uji klinik. Jika obat bahan alam hanya melalui uji praklinik dan standardisasi bahan baku, obat bahan alam tersebut dikelompokkan ke dalam obat herbal terstandar. Dia mengatakan, jika bahan obat alam melewati uji praklinik, standardisasi bahan baku dan uji klinik, obat bahan alam tersebut dimasukkan ke dalam kategori obat fitofarmaka.

Penelitian yang mengantarkan Elin mendapat Habibie Award tahun 2007 terfokus pada penelitian mikroba dan dari tumbuhan. Roadmap peneltian meliputi obat antiinfeksi dan antidegeneratif mengingat penyakit infeksi menduduki urutan pertama pada pola penyakit di Indonesia. Sedangkan penyakit degeneratif terutama penyakit kardiovaskular merupakan penyebab kematian terbesar di Indonesia maupun negara lain.

Beberapa penelitian yang dilakukan Elin yaitu penelitian antibiotik dimana mikroba dicari di tanah di beberapa wilayah Indonesia. Selanjutnya penelitian antituberkulosis jahe dan mengkudu. Sediaan fitofarmaka kapsul jahe dan kapsul mengkudu dapat mempercepat kesembuhan pasien tuberculosis dan relative aman, tetapi tidak dianjurkan untuk ibu hamil. Penelitian lainnya yaitu antibakteri dan antiinflamasi daun babadotan dan jahe, kemudian penelitian antidiabetes dan antihiperlipidemia kunyit dan bawang putih.

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Autis Lebih Disebabkan 'Kecelakaan' Genetis

BOSTON -- Faktor genetis secara dramatis jarang meningkatkan kemungkinan munculnya autis pada anak-anak. Ini berdasarkan hasil penelitian di Boston, Amerika Serikat (AS). Penelitian baru ini berpotensi menjadi pintu gerbang yang lebih baik untuk menyembuhkan autis yang selama ini lebih dikenal disebabkan faktor genetis.

Penelitian dalam kasus autis selama ini memang terfokus pada faktor genetis karena sejauh ini sekitar 10 persen kasus autis diketahui disebabkan faktor tersebut. Namun, para peneliti di Boston memperkirakan faktor gen terindentifikasi hanya menyumbang sekitar satu persen penyakit autis.

Mereka menemukan segmen kromoson yang berhubungan dengan gen dalam perkembangan otak hilang atau terduplikat lebih sering pada orang yang terkena autis dan juga pada orang yang menderita keterbelakangan mental. Ini terjadi dalam beberapa kasus, namun secara acak lebih banyak berasal dari 'kecelakaan' genetis. Hasil dari studi Autism Consortium, yang dimuat di New England Journal of Medicine, mengonfirmasikan bahwa penelitian di AS dan Kanada di tahun sebelumnya, memilah dan menemukan faktor selain faktor genetik itu dalam pengecekan dua DNA lain dalam database. ''Ini sungguh jelas,'' ujar Dr Andrew Zimmerman, direktur Kennedy Krieger Institute'Center for Autism & Related Disorders di Baltimore.

Zimmerman memprediksi, anak-anak dengan diagnosis terbaru autis atau yang mengalami keterbelakangan mental saat ini bisa diketahui melalui kerusakan di kromoson 16. Atau, dengan mempelajari lebih banyak contoh DNA yang mungkin berhubungan dengan autis dari variasi gen lain.

Penelian ini diharapkan menjadi awal untuk digunakan dan diberikan kepada beberapa orang tua yang sering menanyakan, apakah penyebab kasus autis yang menimpa anak mereka. Dan, bagaimana sebaiknya anak-anak di masa depan yang terkena autis segera diketahui pihak keluarga. ''Kami menyediakan banyak petunjuk secara biologi mengenai autis,'' ujar ketua peneliti Mark J Daly.

Ketika sisi biologi digunakan, ujar juru bicara ahli autis Geraldine Dawson, para ilmuwan lain dapat mencoba mendesain obat-obatan sebagai target untuk menyembuhkan autis yang menyerang di otak. ''Saya pikir kromoson 16 akan menjadi isu hangat bagi peneltian autis,'' ujar Thomas Lehner, kepala peneliti genomik di National Institute of Mental Health.

Autis merupakan penyakit yang sangat kompleks dan sulit dipahami, dengan karakteristik si penderita dapat terlihat dari kelakuan yang sulit berinteraksi secara sosial dan sulit berkomunikasi. Peneliti umumnya menemukan bahwa ini merupakan kasus genetik. Adapula yang menduga ini disebabkan adanya merkuri pada vaksin yang diberikan ke bayi.

Perbandingan jumlah anak yang terkena autis di AS adalah satu anak di antara 150 anak normal. Dari studi ini, kelompok peneliti mempelajari keseluruhan 46 kromoson dari DNA dengan sampel 1.441 anak yang terkena autis atau sejenis. Mereka juga mengamati DNA dari sebagian besar orang tua mereka dan 2.800 orang lainnya, yang ternyata diketahui tak memiliki autis.

Peneliti menemukan 25 segmen gen kromoson 16 yang hilang di lima anak yang terkena autis, tapi orang tuanya tidak autis. Ini memperlihatkan di beberapa kasus genetik tidak berhubungan dengan orang tua. Namun, autis tak jarang muncul dari sel telur atau sperma yang mengalami kecelakaan saat dibentuk. Tujuh anak lainnya dengan autis memiliki duplikasi kromoson 16, namun dari semua hanya satu orang tua yang memiliki duplikasi yang sama.

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