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image European Research News Centre > Medecine and Health > How one idea can lead to another
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image image image Date published : 24/02/03
  image How one idea can lead to another
RTD info 36
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  This is the story of how a seemingly unrealistic idea for Aids prevention finally led to the development of a new kind of surgical glove which protects healthcare staff from the risks of viral contamination.
   
     
   

In 1987, the ravages of Aids were being taken increasingly seriously. Gilles Argy, head of R&D at Hutchinson in France, visited a group factory making condoms, accompanied by René-Guy Busnel, director of a research laboratory on animal physiology (CNRS). Wouldn’t it be possible to develop a double sheath, the two layers sealing in a disinfectant able to destroy the Aids virus if the condom tears?' suggested Professor Busnel. But it soon became clear that given the actual conditions under which a condom is used – not to mention the possible harmful effects of virucides on female sexual organs – this type of prevention would be unworkable in practice. Replacing the double layer with a single layer incorporating crushable microcapsules containing the disinfectant seemed equally complex.

Changing target

'The condom was not the right target, but an idea had been sown,' explains Gilles Argy, who subsequently thought of a way of applying the same principle to latex gloves used by surgeons and healthcare staff. At the time, the medical world was growing increasingly concerned at the risk of transmission of the HIV or hepatitis C viruses through contact with the blood of contaminated patients. Injuries to the hands caused by needles or bistoury blades soiled with blood are not, in fact, rare. What’s more, latex does not provide 100% protection as it becomes porous when stretched for long periods. After a lengthy operation surgeons can find that their hands are stained with blood even if their gloves appear intact.

However, crushable microcapsules were not seen as the ideal system. It was not until 1995 that a better solution was found, when Andre Cheymol, project leader at Hutchinson, and Gérard Riess, a lecturer at the Mulhouse School of Chemistry, came up with the idea of using an emulsion. The final concept was born: a kind of 'sandwich' glove consisting of two external layers made from an elastic material with an intermediate layer containing the emulsified disinfecting agent, in the form of uniformly distributed droplets. When a dirty needle punctures the glove, the active agent mixes with the biological liquid on the needle and the blood from the wound.

Delicate problems

There were two problems. First of all, a non-toxic, non-allergenic disinfectant was needed which would be compatible with the latex and destroy the virus very quickly. This product also had to encounter every viral particle introduced. The choice was made by a process of elimination. Among the known molecules, the best candidates were quaternary ammoniums – tensioactive compounds widely used for their disinfecting and detergent properties. They are remarkably effective in dealing with enveloped viruses such as HIV or hepatitis C, especially in the very particular conditions of an accidental scratch or pricking involving very brief contact. 'We now use a more all-purpose mixture with a wider spectrum of activity,' explains Gilles Argy.

The second problem was more delicate. An emulsion had to be found which was sufficiently fluid for the virucide to be released during the few milliseconds it takes the needle to puncture the glove. It was calculated that the droplets needed to be an optimal average of 30 micrometres diameter to be sure they would be perforated by a needle. 'It was a student at Mulhouse, Pierre Hoerner – now a project leader with us – who developed the emulsion, and the equally difficult matter of how to incorporate it in the glove, while working on his thesis,' explains Gilles Argy.

Industrial-scale production

Ordinary surgical gloves are made by plunging moulds – in the form of porcelain 'hands' – into an aqueous latex solution. As water cannot be used in combination with ammoniums, organic solvents had to be used in this case, with all the associated constraints. A German chemicals company, Goldschmidt of Essen, produced the stabilising product, in accordance with Professor Reiss' specifications.

The latex was also replaced by a thermoplastic elastomer, a synthetic material which avoids the allergic reactions natural rubber seems to be causing increasingly among healthcare staff. Once laboratory studies had shown the project to be feasible, in 1996 Hutchinson turned to the European Commission which agreed to finance wider cross-border co-operation helping to launch a pilot production plant under the Biomed 2 programme. Based at the production site of the Hutchinson subsidiary Mapa in Liancourt, France, this unit can produce 400 000 pairs of gloves a year. If this innovation proves as successful as is hoped, the next stage will be to move to genuine industrial-scale production, with continuously automated production lines.

Conclusive trials

In the meantime, the glove has become a reality – thicker, admittedly, than ordinary gloves, but made of a more supple material. The first tests – for mechanical resistance, ergonomy, user tolerance – took place in 2001. They were managed by Biomatech, a company specialising in the preclinical and clinical evaluation of medical devices, in co-operation with the Lyon Sud hospitals in France where clinical trials were conducted in the autumn of 2002.

Jean-Louis Caillot, the surgeon who supervised these trials, reports that 'the dozen specialists who tried them believe that freedom of movement is no longer affected after just a few minutes adaptation. The surgery took place in conditions close to those with a traditional double-gloving.' Orthopaedic surgeons, who are familiar with this system, 'got used to them a little quicker than some of their colleagues who still only use a single pair of gloves'. Another advantage is that during 'normal' use, that is without perforation, the protection is perfectly impervious to bacteria and even viruses. More interesting still, the layer of emulsion is a barrier which destroys or blocks viruses which would try to penetrate if the glove were accidentally punctured. As a result, however long the surgery lasts, the surgeon's hands never come into contact with the pathogenic agents which may be present in the patient's blood.

The next step? Before they can be made commercially available, the gloves need the recognised EC mark required for all medical devices – the procedure for this is already in progress. Also, early in 2003, Professors Stanley Plotkin and Fernand Bricourt will publish an article on the purely scientific aspect of the project in the Journal of Medical Virology. 'This is essential to ensure product credibility,' explains Gilles Argy. Apart from hospital staff, Hutchinson believes that NGOs, emergency services and military personnel operating in regions with a high viral risk could be potential users of the glove.

Finally, it should be made clear that although this glove greatly reduces the viral charge (by about a factor of 15), and thus the likelihood of the transmission of a disease, it does not eliminate it altogether in the event of an accident involving contact with blood. Healthcare staff must, therefore, continue to remain vigilant at all times.

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To find out more:
http://www.hutchinson.fr


Contacts
pierre.hoerner@ms.hutchinson.fr
gilles.argy@paris.hutchinson.fr


The pilot plant at Liancourt (FR), able to produce 400 000 pairs of virucide gloves a year, has a pre-industrial area (with steeping machine) and control laboratory with a dedicated virology zone.

The pilot plant at Liancourt (FR), able to produce 400 000 pairs of virucide gloves a year, has a pre-industrial area (with steeping machine) and control laboratory with a dedicated virology zone.


Biocide medical gloves
With European support of €1 785 000 (50% of the cost of the pilot production unit) under the Biomed 2 programme, the Biocide Medical Gloves project started in 1997. The partners came from the public and private sector in France and Germany: Assistance Publique/Hôpitaux de Paris; Institut national de la recherche médicale (Marseilles and Lyons); Institut national de la recherche agronomique (Maison-Alfort); Institute of hygiene (Hamburg); Biomatec (Lyons); Mapa SNC (FR); Goldschmidt SA (DE); and the University of Essen (DE).

 


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