SVTR

La Commission européenne a donné son feu vert au financement d'un registre européen de lignées de cellules souches embryonnaires humaines, jeudi 29 mars ...

Bientôt un site Internet avec des informations sur les essais

Janez Potočnik a précisé également que l'Union européenne s'engage sans restrictions "à ce que son programme de recherche respecte les normes les plus strictes possibles en matière d'éthique" : "Nous avons défini dans notre programme un environnement strict et transparent pour l'utilisation de ces cellules", a-t-il affirmé.

Un site Internet accessible au public contiendra des données sur ces lignées (par exemple, sur les caractéristiques des cellules) et diffusera des informations sur des développements intéressants, tels que les essais cliniques.

Il fournira par ailleurs des précisions sur l'origine des lignées de cellules souches et les coordonnées des personnes de contact. 81 lignées différentes sont actuellement utilisées dans des projets de l'UE. Le registre contiendra aussi des informations obtenues sur les lignées de cellules souches embryonnaires humaines utilisées dans les projets en cours et futurs financés par l'UE.

10 Etats membres de l'UE sont associés

On entend par "lignée de cellules souches embryonnaires humaines" une culture de cellules souches isolées à partir d'un embryon humain à un stade précoce, ces cellules pouvant être multipliées à l'infini en laboratoire. ...

http://www.la-croix.com/article/index.jsp?docId=2299059&rubId=5547  

 

Des manifestations sont organisées jusqu'au 31 mars dans toute la France à l'occasion de la « semaine sans pesticides»

Le système agricole français est-il « verrouillé » ? Oui, ont répondu les scientifiques de l'expertise collective « Pesticides, agriculture et environnement » menée par l'Institut national de la recherche agronomique (Inra) et l'Institut de recherche pour l'ingénierie de l'agriculture et de l'environnement (Cemagref) (1).

Le modèle agricole français fait difficilement sa mue. Et les experts d'énumérer certains des blocages : la rationalité économique basée sur les rendements « induit le recours aux pesticides » ; « un secteur de conseil en protection des cultures dépendant de la vente des pesticides tend à favoriser l'emploi de pesticides » ; le fait que ce soit « les mêmes entreprises » qui assurent « la distribution des semences, des pesticides et des engrais, et la collecte des récoltes » renforce cette tendance, d'autant plus que ces mêmes entreprises rechignent à distribuer des variétés rustiques ou résistantes à certains bio-agresseurs, etc.

Les scientifiques ajoutent des arguments socioculturels : la « culture du champ propre », sans mauvaises herbes ni maladies, prégnante chez les agriculteurs, l'aversion à l'idéologie « écolo » considérée comme « illégitime dans l'univers socio-technique de l'agriculteur » ou l'« aversion au risque » qui pousse aux traitements systématiques, d'autant plus qu'une pratique économe en pesticides exige à l'inverse plus de connaissances et une présence accrue dans les champs.

La France, troisième consommateur mondial de pesticides

Ce constat très officiel explique que la France reste le troisième consommateur mondial de pesticides (78 000 tonnes en 2005) sans qu'aucune tendance nette à la baisse ne se dessine au-delà des variations annuelles : après les années record de consommation 1998-2001, avec un marché annuel de phytosanitaires autour de 2 milliards d'euros, celui-ci oscille depuis entre 1,6 milliard et 1,9 milliard d'euros (1,7 milliard pour 2006).

Or, ces consommations massives sont à l'origine d'une pollution chronique des eaux, jugée « préoccupante » par l'Institut français de l'environnement : 229 substances chimiques différentes ont été identifiées dans les eaux de surface, et 166 dans les nappes d'eau souterraines ; 49 % des points de mesure présentent une qualité moyenne ou mauvaise, selon l'institut.

Une deuxième expertise historique apporte un éclairage tout à fait inédit sur la genèse de cette situation. Pesticides, révélations sur un scandale français (2), l'ouvrage de François Veillerette, président du Mouvement pour les droits et le respect des générations futures (MDRGF) qui milite pour les alternatives aux pesticides et organise la « semaine sans pesticides », et de Fabrice Nicolino, journaliste, chroniqueur dans le cahier « Sciences & éthique » de La Croix, remonte aux sources du système agricole national.

Confusion et collusion des intérêts

Les deux auteurs ont mené une étude fine de ces hommes qui ont fait l'agriculture française après la guerre. Les objectifs éminemment louables de l'autosuffisance alimentaire inciteront à s'engouffrer sur la voie de l'agriculture intensive : tous travailleront main dans la main au service de la cause commune, les services du ministère de l'agriculture, notamment le service de la protection des végétaux et la commission d'étude de la toxicité, les scientifiques de l'Inra et les industriels dits « de la protection des plantes » qui développent les engrais et les produits chimiques.

Très vite cette complicité se transformera en confusion et collusion des intérêts, les mêmes hommes clés se chargeant de concevoir les substances chimiques à mettre sur le marché, de développer des variétés de plus en plus productives et en même temps d'homologuer et d'étudier la toxicité de ces substances.

Dans ce système, l'administration n'est plus à même de défendre l'intérêt collectif, de garantir la protection de la santé et des milieux, et les agriculteurs eux-mêmes sont loin de maîtriser les règles du jeu. ...

http://www.la-croix.com/article/index.jsp?docId=2298767&rubId=5547  

Published online: 2 April 2007; | doi:10.1038/news070402-1 / http://www.nature.com/news/2007/070402/full/070402-1.html

Link suggested between soccer and motor neurone disease

Experts call for investigation into sport and fatal brain condition.

Michael Hopkin

British neuroscientists are planning to investigate whether playing soccer contributes to the development of motor neurone disease. The move comes after three amateur footballers playing in the same league developed the disease, which normally affects less than one person in every 50,000 each year.

Experts are now aiming to launch a full epidemiological study of professional footballers and motor neurone disease (MND) patients, to see whether the sport really does raise the incidence of the disease among those who play it at a high level.

Details of the patients, all of whom were committed footballers, are published in the journal Amyotrophic Lateral Sclerosis¹ - a publication named after the most common form of MND. The patients range in age between 56 and 61 years old, and were all diagnosed with the disease within a decade of each other.

"What is unusual about this group is that they are all friends who developed MND at the same time," says Ammar Al-Chalabi of King's College London, one of the experts who described the cases. "A cluster like this could occur by chance, but the odds are quite long."

The three have several potential risk factors in common, including having been electrocuted by mains electricity at some point during their lives. But the authors note that the three were very keen at football, playing more than twice a week - almost as much as professional players.

"The next step is a proper epidemiological study," Al-Chalabi adds. He and his colleagues are planning to approach the Professional Footballers' Association to request data on former professional footballers, to see whether they have a higher than normal incidence of the disease.

Blows to the head

A possible link between football and MND, which causes paralysis and is ultimately fatal, has been found before. In 2005, Italian researchers reported that professional footballers playing in that country between 1970 and 2001 were more than six times more likely to have developed the condition². These findings were a by-product of a study looking for evidence of past steroid abuse among footballers.

MND has a wealth of possible causes, including genetic factors. The most obvious suggestion in the case of soccer players is that repeated heading of the ball might harm the brain. Many boxers, most notably Muhammad Ali, who now suffers from a form of Parkinson's, have suffered brain diseases as a result of repeated blows to the head.

But two of the three English patients say they avoided heading the ball during play. And MND involves the death of motor neurons, most of which are deep in the brain and spinal cord, and would therefore be less likely to be damaged by impacts to the skull.

Another theory is that harmful pesticides on the grass, or compounds in the paint used to mark the pitch, might find their way into the bloodstream through minor grazes or even directly through the skin when the ball hits it, Al-Chalabi and his colleagues suggest. It is clear that some chemicals can kill nerve cells, although there is no established link to MND.

Yet another possibility is that the frequent high activity of motor neurons in sportspeople may generate large amounts of chemical waste products that damage nerve cells, leading to an increased likelihood of developing MND later in life.

Keep on playing

"Basically, all theories are valid at the moment. That's part of the problem," comments Brian Dickie, director of research development at the Motor Neurone Disease Association.

Dickie says that "it's worth seeing if the Italian study could be replicated" in a study intended to look for a link between football and MND. He is currently spearheading the creation of a database of 1,500 MND patients and 1,500 carefully matched control volunteers, in a bid to tease out some of the causes of this rare condition.

Meanwhile, Dickie is at pains to point out that the health benefits of sport far outweigh the possible negatives. "Don't let this stop you playing football," he urges. "The Italians had a sixfold increase in likelihood of MND. That sounds like a lot but a sixfold increase in a rare disease still means it's a rare disease."

References

1. Wicks P., et al. Amyotrophic Lateral Sclerosis, doi: 10.1080/17482960701195220 (2007).
2. Chio A., Benzi G., Dossena M., Mutani R. & Mora G. Brain, 128 . 451 - 453 (2005).

Published online: 1 April 2007; | doi:10.1038/news070326-16 / http://www.nature.com/news/2007/070326/full/070326-16.html

Warmer waters could spin the Earth faster

The oceans' heating will shave instants off the day.

John Whitfield

Stranger than fiction: on 1 April 2004, news@nature.com reported that climate change was making the day longer - as an April Fools' day joke. "I'm astonished we got anywhere close to the truth," says Nicola Jones, author of the original piece. "I just made that up." NASA

The warming of the world's oceans is going to shorten the day, say German researchers. But there's no need to adjust your watch: the shortening will be by only 0.12 milliseconds over the next 200 years, they estimate.

As water warms, it expands, causing sea level rise. Felix Landerer of the Max Planck Institute for Meteorology in Hamburg, Germany, and his colleagues used a computer model to find out what effect this expansion will have on the distribution of water around the globe.

The researchers looked only at heating, and not at the melting of the ice caps. So in their model, the change was not in the total mass of water in the ocean, but in the water's density and distribution. As the ocean expands and water creeps up the shorelines, the net effect is to transfer mass away from the central ocean and towards the shore.

Two factors mean that this tends to move water's mass away from the equator and towards the poles. First, the depths of the North Atlantic should warm more quickly than depths elsewhere, thanks to a current there that carries water down from the surface. So the expansion and movement of water is strongest there. Second, a quirk of our planet's geography means that the continental shelf's surface area happens to be larger at high latitudes than around the equator.

Having more mass at the poles, which is closer to Earth's axis of rotation, will make the planet spin faster. "It's like a figure skater doing a pirouette," Landerer explains. "When the arms are close to the body, you turn quicker than when they are stretched out." He reports the results of his model in Geophysical Research Letters¹.

"It highlights how massive a change [in climate] is going on," says Richard Gross, an expert on the Earth's rotation working at the Jet Propulsion Laboratory in Pasadena, California. "The Earth is such a large body that it takes a huge change in mass distribution to show up in rotation."

What time is it?

"If you warm the ocean at different depths and places, water is going to spill over," agrees Rui Ponte, a climate researcher at Atmospheric and Environmental Research in Lexington, Massachusetts.

But, he says, whether and how this will affect the length of the day is less certain because we don't know much about how the oceans' depths respond to warming. "The models have various approximations and problems," notes Ponte. And melting ice caps, he points out, might take mass away from the poles and distribute it more evenly around the planet, counteracting the effect that Landerer highlights.

Several other factors also affect the length of an Earth day. The Moon's gravitational pull, for example, lengthens the day by 2.3 milliseconds a century. And interactions between Earth's liquid core and its solid mantle layer are also thought to subtly change day length.

In 2002, a group of researchers argued that climate change could make the day longer, by 0.1 millisecond a century, because of an increase in winds blowing from west to east - the opposite direction to the planet's rotation².

If all these predictions are accurate and complete (which is almost certainly not true), then that should add up to a day being 2.34 milliseconds longer a hundred years from now. That's a measurable difference, although it is important to keep in mind that day length varies by about one millisecond from day to day, says Gross, mainly because of changes in the winds.

Landerer's team are now trying to work out the other effects of redistributing the ocean. For example, he says, the Earth's axis could move slightly, changing the position of the geographic poles.

References

1. Landerer F. W., Jungclaus J. H. & Marotzke J. J. Geophys. Res. Lett., 34 . L06307 (2007).
2. de Viron O., Dehant V., Goosse H. & Crucifix M. Geophys. Res. Lett., 29 . (2007).

http://www.nature.com/news/2007/070326/full/070326-17.htmlPublished online: 1 April 2007; | doi:10.1038/news070326-17

Blood made suitable for all

Stripping blood of antigens means it can be given to anyone.

Alison Abbott

Scientists have discovered enzymes that can efficiently convert blood groups A, B and AB into the 'universal' O group - which can be given to anyone but is always in short supply.

The two novel glycosidase enzymes were identified in bacteria by an international team led by Henrik Clausen of the University of Copenhagen in Denmark. The researchers hope that the enzymes will both improve the erratic supplies of blood around the world, and also the safety of transfusions. Clinical trials to test the safety and effectiveness of their converted blood are being planned.

The ABO blood-type system is based on the presence or absence of the sugar-based antigens 'A' and 'B' on red blood cells. Type O blood cells have neither A nor B antigens, so may be safely transfused into anyone. But types A, B and AB blood do, and cause life-threatening immune reactions if they are given to patients with a different blood group. The bacterial glycosidase enzymes strip these antigens away from A, B and AB blood.

The idea of such antigen-stripping goes back to the early 1980s, with the discovery of an enzyme in coffee beans that removes B antigens from red blood cells. Early-stage clinical trials showed that the converted blood could be safely transfused into individuals of different blood groups; no traces of enzyme or antigen remained to cause reactions. But the enzyme reaction was far too inefficient to make large-scale conversion practical.

Clausen's team screened 2,500 extracts from different bacteria and fungi for their ability to cleave off A and B antigens. The newly discovered bacterial 'B' enzyme is nearly 1,000 times more efficient then the coffee-bean B enzyme - the additional discovery of an enzyme to remove A antigens means that all blood types can now be converted. The work is reported in Nature Biotechnology.

Common stock

Type O is the most common blood group, but stocks constantly run low because it is used in all emergency situations where there is no time to determine the patient's own group.

An additional pressure on type-O blood, particularly in the United States, comes from the mismatch between blood donors and recipients. Most US donors are Caucasian, amongst whom 45% of people are blood group O. But more than half of African Americans, and nearly all native Americans are O, and so require type-O blood.

Also the donor population is shrinking as fears of transfusion-transmitted infections of new diseases such as SARS, mad-cow disease and West Nile disease remove from the pool donors who may have been exposed.

"Restrictions are getting almost comical," says Martin Olsson, head of the Lund University Hospital Blood Centre in Sweden, and a member of the international team. "At different times, the US excluded from donation those who had recently visited Europe in case they had contact with BSE, and Europe has excluded those who recently visited the US where they perceive a higher risk of HIV."

Yet in practice the greatest risk in blood transfusion is not the transmission of disease but the accidental transfusion of the wrong blood group, he says. "As a clinician, I see the biggest advantage of the new enzyme technology as eliminating incidents of giving the wrong blood."

The Boston-based company ZymeQuest is developing the enzyme technology for commercial use in blood centres. Early-stage clinical trials are underway. If all goes well, blood centres could be using the technologies in just a few years.

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Vers un sang humain universel

Des chercheurs ont trouvé le moyen de supprimer les groupes sanguins. Une découverte révolutionnaire qui pourrait, à terme, mettre fin au manque de dons

Pouvoir transfuser du sang à n'importe qui, sans se soucier de son groupe sanguin : cela devrait devenir possible d'ici à quelques années, si l'on en croit la découverte réalisée par une équipe franco-américaine rassemblant des biologistes du CNRS, de l'université Aix-Marseille et de la société américaine ZymeQuest. Leurs travaux viennent d'être publiés dans le mensuel international Nature Biotechnology.

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