Gene therapy has made color vision to monkeys.

Gene therapy has made color vision to monkeys.

Gene therapy has made color vision to monkeys

Two squirrel monkeys, who could only distinguish yellow and blue, acquired a complete perception of colors through the insertion of a human gene in their retina. This discovery, which is surprising, suggests possible treatments for diseases of vision, even congenital.

Sam and Dalton are two squirrel monkeys, also called sairmi (Saimiri sciureus), hence the name of the first. Two years ago, like all males of their species, they could only distinguish two shades, yellow and blue, but neither red nor green. Hence the name of the second, which is that of John Dalton, the English physician who described in 1798 this hereditary disorder of the vision called since color blindness. Today, Sam and Dalton triumph over all the tests imagined to detect this disease, as evidenced by a publication in the journal Nature.

For the past ten years, these two monkeys have been living with Maureen and Jay Neitz, a couple of ophthalmologists working at the University of Washington ("they're like our kids," they say). Sam and Dalton were extensively trained in color vision screening tests, judging by the video shot by the team.

Meanwhile, William Hauswirth's team (University of Florida) was developing a method of gene therapy to slide a gene into some cells of the retina, the cones, responsible for color vision. In male squirrels, there are no cones perceiving green and red. They are dichromates (like cats of both sexes), while females - and non-colorblind humans - are trichromatic.

The brain has also found the colors

Two years ago, these two monkeys underwent an intervention to receive genes, of human origin, conveyed into the cones by a harmless adenovirus. These genes are used to make a protein of the opsin family, these light-sensitive pigments that function within a molecular complex called rhodopsin.

After the success of this intervention, the question was twofold. Will the cones thus treated develop a real sensitivity to colors? And, above all, will the brains of Sam and Dalton, who have never seen either red or green, know how to analyze these completely new signals?

According to Maureen and Jay Neitz, who live continuously with both animals, the first effects appeared after only five weeks. Twenty weeks after the intervention, Sam and Dalton began to point, during tests, the red and green areas displayed on the screen. Jay Neitz says he himself was surprised.

The team then continued testing for a year and a half to ensure performance and progress. Today, Sam and Dalton visualize the colors as well or almost as the females of the species. Moreover, after two years, no side effects were noted.

A therapeutic hope

"The addition of a third opsine in an adult who does not see either green or red leads to the normal behavior of a trichromatic vision," the authors conclude in the journal Nature. According to Jay Neitz, experience shows that even in these monkeys that do not recognize all the colors, the neural circuits capable of analyzing them are present in the brain. It can also be interpreted as a great plasticity of the central nervous system.

On the medical level, this result is of great interest. This is not the first time that gene therapy improves vision. Success has already been achieved in dogs and humans in the case of Leber's congenital amaurosis.

It shows that it is possible to treat sight disorders, even when the origin is congenital, which was not self-evident. Moreover, as the authors point out, the DNA used for the repair was human, which is one less problem for the transfer of this technique to humans.

Particularly targeted are vision disorders involving cones, such as color blindness but also loss of central vision, such as macular degeneration, due to age or diseases, including diabetes.

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Towards an anti-cocaine vaccine.

Towards an anti-cocaine vaccine

Cocaine addiction could be countered by a simple vaccine?

US researchers say the vaccine they have created is causing cocaine addicts to abandon their drug use. In fact, the injected substance increases the level of antibodies against the drug, which makes it inactive before it reaches the brain and produces its euphoric effects.

Teams from Yale University and Baylor College come to this conclusion after six months of clinical trial.

The results show that 38% of vaccinated cocaine addicts produce a sufficient level of antibodies to block the effects of the drug. As a result, cocaine use has plummeted, with some consumers ceasing to take any.

A downside however: the effects have not persisted for more than two months.

The authors therefore believe that optimal treatment would require repeated vaccinations to maintain adequate antibody levels.

The lead author of the study, Thomas Kosten, has been developing a cocaine vaccine for 15 years.

"Fifteen years ago, everyone said that it was impossible to produce antibodies against small molecules like this one. Dr. Thomas Kosten

According to the International Narcotics Control Board, cocaine is the second most commonly used drug in North America, accounting for 2.3 million users in the United States alone.

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AIDS: proposal for widespread screening of the population.

AIDS: proposal for widespread screening of the population

The High Health Authority (HAS) recommends that screening the AIDS virus is systematically offered to the entire population, aged 15 to 70, in order to make up for France's "serious delay", where some 40,000 people are unaware that they are HIV-positive.

"It is not a question of organizing a massive screening in which we would pass the whole population, it is to trigger a reflex, especially among doctors," AFP Etienne Caniard, a member of the Collège de France, told AFP. the HAS. "There is nothing compulsory," he said.

Every year, France records 6,000 to 7,000 new infections with HIV.

Asked by the Directorate General of Health, the report on the HIV testing strategy was to be presented next week. After the revelations of the newspaper Libération, the HAS decided to put it on line Wednesday.

"The major element" that led the HAS to advocate a generalization of screening is the finding of "a significant delay," said Mr. Caniard. "People very often find out that they are HIV-positive, which poses huge individual and collective problems," he said.

This delay deprives them of access to effective treatments and exposes others to a significant risk of contamination, while treatments can lower the viral load and reduce contamination.

Populations identified as at risk are not the most concerned by the delay in screening, said Mr. Caniard. These are "people who are married, have children, are of a certain age, who may have practices that lead them to take risks, but who do not consider themselves to be at risk and therefore neglect the screening process. ".

At the same time, the HAS recommends to "amplify and better organize systematic screening for at-risk populations": men who have sex with men, heterosexual men with multiple partners, injecting drug users, people from high-risk areas prevalence like Sub-Saharan Africa or the Caribbean ...

Françoise Barré-Sinoussi, Nobel Prize in Medicine 2008, declared herself "in favor of voluntary testing, as long as it is not mandatory and based on accountability". "We feel empowered if we explain things to you," she told AFP on the sidelines of the International HIV Vaccine Conference in Paris.

A favorable opinion also from Jean-François Delfraissy, Director General of the National Agency for Research on AIDS, who estimated on France-Inter that "we must take into account the heterogeneity of the epidemic in France".

"Clearly, we have to move on screening proposals," he said, citing rapid screening tests or "screening proposals that are made by the community itself."

Asked about the risk of stigmatization, Mr. Caniard noted that "it still exists, but in a slightly different way from what we have seen". "When faced with an epidemic that was largely unanswered, the risk of stigmatization was much greater than it is today," he said.

"We continue to recommend all the precautions for screening around HIV: confidentiality, respect for the person," he said.

The HAS is an organization that makes recommendations, the decision-making being the responsibility of the Ministry of Health.

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Saturated fatty acids increase appetite for several days

Saturated fatty acids increase appetite for several days

The leptin hormone and insulin play key roles in the mechanisms of appetite and food intake. In healthy people, leptin, which is secreted by adipose tissue, cancels the feeling of hunger and insulin, which is at its highest when blood glucose increases after a meal, causes the brain to decrease the taste of food .

A study, published in the September issue of the Journal of Clinical Investigation, shows that saturated fat interferes with the ability of the brain to respond appropriately to these signals.

Stephen Benoit, a researcher in behavioral neuroscience at the University of Cincinnati, and his colleagues found that after only three days of a diet high in saturated fat (found, for example, in beef and cheese), Rodent brain became resistant to leptin and insulin. Unsaturated fats, such as those contained in olive oil, did not trigger such resistance.

As a result of this resistance, a meal high in saturated fat increases appetite. "Taking leave of a healthy diet by eating fast food can have consequences that last a few days, even after you have resumed the healthy diet," says Benoit.

Feeling leptin and insulin is like keeping an eye on the state of nutrients in the body, says Gary Schwartz, a neuroscience researcher at Albert Einstein College of Medicine in New York, who is not involved in this research . "If that eye goes blind because too many nutrients are provided, it can not respond. (...) A vicious cycle of metabolic problems and weight gain can result.

Why does the body react like this? A possible explanation advanced by the researchers, inspired by an evolutionary approach, is related to the mechanisms involved in hunger. When a person is hungry, the body starts using its energy reserves. As a result, the blood becomes fat-fed, just as it does in the case of obesity and overeating. Cautious, the brain would interpret fat intake as a sign of starvation. "During evolution, humans have been facing a lack of calories and starvation much more than we have ever faced with an overabundance of calories," says William Banks of the St. Louis Veterans Affairs Medical Center. .

But, Benoit notes, a neurological response "that was helpful at some point in history is no longer useful when there is a McDonald's and a Taco Bell on the way home." So, in the battle against empty calories and obesity, "sticking to a Mediterranean diet, rich in olive oil and vegetables can help thwart the obsolete physiology of our brain."

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New gene therapy successfully tested against Parkinson's.

New gene therapy successfully tested against Parkinson's

Injection of three genes in the brain helps revive dopamine production and improve the motor skills of people with Parkinson's disease, according to French researchers.

By injecting three genes into the brain, French and British researchers have been successful in improving the symptoms of Parkinson's disease in macaque monkeys.

This technique has also been tested on some patients with advanced forms of neurodegenerative disease, with encouraging results, according to Prof. Stéphane Palfi, neurosurgeon at Henri-Mondor Hospital in Créteil and researcher at MIRCen in Fontenay-aux- Roses (Molecular Imaging Research Center, CEA / CNRS).

Parkinson's disease is characterized by a degeneration of neurons producing dopamine, a neurotransmitter essential for movement. Patients suffer from stiffness, tremors, difficulty initiating gestures ... The administration of L-dopa, a precursor of dopamine, corrects these symptoms but eventually leads to uncontrolled movements. Current research therefore aims to develop a more regular and constant intake of dopamine. One of the ways is to restore this production in the dark substance, the dopamine manufacturing site in the brain.

For this, the team of Stéphane Palfi and Béchir Jarraya has developed a gene therapy with three essential genes for the synthesis of dopamine. These genes were injected into the brain using a viral vector, an equine lentivirus made harmless. The product was developed by the British company Oxford Biomedica.

MIRCen researchers first inserted these genes into macaque monkeys whose parkinsonism is caused by the injection of a toxin. The researchers found that movement control improved rapidly and sustainably over the 44 months of follow-up, without the side effects seen with prolonged treatment with L-dopa.

In a so-called preclinical trial, some patients received the same therapy at Henri-Mondor Hospital: one year later, their motor skills improved, the researchers underline, and the treatment is well tolerated. A first phase of clinical trial could follow soon.

Two years ago, a British team published the positive results of the first clinical trial of gene therapy against Parkinson's disease, exploring a different pathway: the stimulation of the synthesis of Gaba, another neurotransmitter involved in movement.

The results of the MIRCen team are published this week in a new scientific journal of the Science group, called Science Translational Medicine. Translational medicine is based on a better synergy and more multidisciplinary so that the fundamental results reach the patients faster.

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Cosmetic lenses are dangerous for the eyes.

Cosmetic lenses are dangerous for the eyes!

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Want to make you a cat's eye or a red eye of vampire for a Halloween party? Or simply blue or green eyes to change a little everyday? Attention, cosmetic lenses can also cost you the view.

When it is not accompanied by the necessary precautions, the wearing of cosmetic lenses subjects the eye to serious risks: "infection, abscess of the cornea or loss of the eye" enumerates the doctor Jean-Michel Muratet, member of the SNOF (National Union of Ophthalmologists of France). Those who use them rarely know the rules of maintenance. Just like the lenses prescribed by a professional, these lenses should be used properly.

Essential precautions

Wash your hands before putting them on, do not wear them for more than 12 hours in a row, clean them with a suitable product (never in the water!), Remove them to sleep and especially, do not lend them ! Any sign of warning (pain, abnormal secretions, watery eyes, redness ...) should cause you to remove them, and urgently consult an ophthalmologist. For maximum safety, consult before purchase: the medical examination will determine if you can wear any lenses, and the doctor will inform you of the precautions to take.

In the United States, these lenses belong to the medical sector

On the occasion of Halloween, the US Food and Drug Administration (FDA) warns users of decorative lenses. There, in fact, these products come under the status of medical device. As such, an ophthalmologist visit and prescription are required to obtain one.

In France, "decorative lenses are unfortunately not a medical device, no visit to an ophthalmologist is mandatory before or after their use. So you can get it everywhere, without a prescription "regrets Jean-Michel Muratet. Since 2004, the SNOF has asked for a change of legislation.

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Gene therapy against congenital blindness: another good result.

Gene therapy against congenital blindness: another good result!

A new victory has just been won against amaurosis Congenital Leber, which most often leads to complete blindness in adulthood. Last year, four people had recovered some of their vision. Today, the same genetic technique has proven itself by demonstrating that it works much better in children.

9-year-old Corey Haas is now able to ride a bike, and a video shows him walking along a signposted path full of obstacles. Yet, Corey was born with one of the forms of Leber's Congenital Amaurosis (or LCA, its English name). This disease, which affects the photoreceptors, causes a big deficit of vision at birth which evolves most often in a total blindness towards forty years. We know today that the cause is genetic. One of the genes needed to synthesize a photoreceptor works poorly. Several genes are involved and so there are as many forms of this disease (at least 11 currently known).

Corey is suffering from the so-called LCA2 form. At home, it is the RPE65 gene that hurts its work whereas it should induce the synthesis of rhodopsin, one of the pigments of the retina, present in the sticks. These cells end up, over the years, by dying.

For years, researchers have been exploring the path of gene therapy to combat several forms of genetic blindness, including Leber's amaurosis. In 2006, a team from Inserm Nantes managed to partially restore the sight to dogs suffering from this disease (also due to a mutation of the RPE65 gene). In April 2008, a big first was announced in humans. Two independent teams, in the United States (University of Pennsylvania) and the United Kingdom (University College, London), improved the vision of four people with ACL2 out of the eight who received treatment.

In both cases, the method consists in integrating an RPE65 gene in a harmless adenovirus introduced into the retina, so that it then enters the photosensitive cells. This is the same way the Pennsylvania team used again today, announcing excellent results today.

Two years without side effects

Two years ago, Albert Maguire, Jean Bennet and their colleagues treated 12 patients, aged 8 to 44, including four children, the oldest being 11 years old. The results, which have just been published in The Lancet, show that in all cases, vision has improved significantly, according to experimental measurements and according to subjective criteria. Above all, the study shows what had already been noted in dogs, namely that the method gives much better results in the young.

The injection of the RPE65 gene, in fact, will have even more effects as the target cells still alive are more numerous. As the disease progressively leads to the death of these cells, the impact of treatment diminishes with age. The researchers note that the youngest of the 8-year-old treated children regained a sensitivity to light identical to that of a normal child of the same age. The positive effects are felt in the first months after treatment and have continued during the two years of the study, without undesirable side effects.

The gene therapy has just again scored points, at least against the congenital amaurosis of Leber. Other recent studies in mice show good results for another disease, retinitis pigmentosa and color vision have been restored in squirrel monkeys. However, there is still a lot of work to be done, starting with clinical trials on a larger number of patients.

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Gene therapy saves two children from adrenoleukodystrophy.

Gene therapy saves two children from adrenoleukodystrophy

Two children with adrenoleukodystrophy have been saved from certain death thanks to gene therapy ... and an inactivated derivative of the AIDS virus!

Adrenoleukodystrophy (ALD) is a rare but deadly genetic disease. It leads to the progressive destruction of the central nervous system (spinal cord and brain), leading to loss of cognitive and motor functions and death. Bone marrow transplantation is not enough: donors are too rare and the risk of complications is high.

A new treatment has just been tested on two children, at the Saint-Vincent-de-Paul hospital in Paris, by French research teams associating Inserm, the Assistance Publique Hôpitaux de Paris and the Université Paris- Descartes. Stem cells from the bone marrow of small patients were removed, modified in the laboratory and then reinjected into the patients.

A vector - a sort of vehicle carrying genetic information - derived from the AIDS virus was associated with it. The AIDS virus is indeed the only one able to penetrate into the nucleus of cells that do not divide: stem cells and neurons. These, reached by the ALD, thus received the therapeutic gene created by the researchers. No side effects have been observed so far.

This world first offers treatment perspectives for all leukodystrophies, as well as for other more frequent diseases (hemophilia, Parkinson ...). The European Association Against Leukodystrophies (ELA) is pleased with this result and the resulting perspectives. It intends to continue to support research, and thus extend testing to the whole of Europe.

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NicVAX ®, the next vaccine to stop smoking?

NicVAX ®, the next vaccine to stop smoking?

NicVAX ® is a vaccine candidate conjugate still experimental for the treatment of Nicotine dependence and relapse prevention.

NicVAX® tackles the "market" of smoking, the leading cause of preventable death worldwide. By affecting 1.2 billion smokers worldwide, smoking is responsible for 5.4 million deaths a year. Relapse remains a considerable challenge for smokers and the relapse rate reaches 90% in the year following the cessation.

The vaccine is designed to stimulate the immune system to produce antibodies that bind to nicotine. A nicotine molecule attached to an antibody is too big to cross the blood-brain barrier. As a result, NicVAX blocks prevent nicotine from reaching its receptors in the brain and at the same time prevents the sensation of pleasure experienced by smokers. Early clinical trials show that NicVAX has the ability to prevent nicotine from reaching the brain and may help quit smoking. Because the body's immune system can be stimulated to produce long-lasting antibodies, Nabi believes that the candidate vaccine could also be effective in preventing relapse.

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Human skin recreated from stem cells.

Human skin recreated from stem cells

A French team has succeeded in recreating the together an epidermis, the superficial layer of the skin, from human embryonic stem cells, a first that could find a rapid application in the treatment of burn victims.

For several years, doctors have been using cell therapy to treat burn victims: they reconstitute skin from a small sample taken from the patient himself. The problem comes from the time needed to cultivate a sufficient area of ​​epidermis (three weeks), during which the burn is unprotected, with risks of infection, dehydration ... Techniques have been developed to fill this period of time. waiting, but they are far from optimal.

It is this period that the work of the team led by Marc Peschanski (Institut I-Stem), published in the journal The Lancet dated Saturday, has targeted, explained the researcher to AFP.

The first step was to obtain skin cells (keratinocytes) from human embryonic stem cells, both capable of differentiating into all types of human cells and reproducing indefinitely.

From these keratinocytes, they then succeeded in reconstructing "in vitro" an epidermis with its various layers, including the stratum corneum, the most superficial one. A study conducted in collaboration with a biotechnology company specialized in the skin made it possible to verify "that it was a perfectly normal epidermis".

The last step was carried out with Spanish researchers mastering a technique of implantation on the mouse. The epidermis reconstituted in the laboratory was thus grafted onto mice.

"We waited three months and the human skin has been renewed three times, since it is renewed every month completely. We made human skin, "said Professor Peschanski.

To switch to an application in humans, now remains to achieve a transfer of technology. "We started working on it, it will take a little while, because we have to validate everything, but it's not science anymore, it really becomes technical application," said the researcher. .

He tables, "if everything goes well", on a passage in the man "for the end of 2011". "But knowing that it's a calendar hanging from a number of threads that can be cut at any time."

Several researches on embryonic stem cells are now coming to an end, close to the transition to the application on humans:

  • The Californian company Geron has already received authorization in the United States to carry out a clinical trial to treat spinal cord injuries.

  • Another American company, Advanced Cell Technology, has filed a license application for trials on patients at risk of losing their eyesight due to Stargardt's disease.

  • A third is working on a diabetes treatment.

  • In France, Philippe Menasché tests on the monkey a treatment of infarction.

  • Marc Peschanski is also working on induced pluripotent cells (iPS), resulting from the reprogramming of the nucleus of differentiated adult cells. The I-Stem Institute was created by the National Institute of Health and Medical Research (Inserm) and the French Association against Myopathies (AFM), organizer of the Telethon.

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