--- Erik Reuter <[EMAIL PROTECTED]> wrote: > William T Goodall wrote: <snip> > > As for removal - it would be much easier to insert > >a rice-grain sized > > chip deep into the abdomen (say) than it would be > >to surgically remove it. > > Could you elaborate? Since these things are > (obviously) designed to be > scanned, it would be easy to pinpoint the location > with a hand-held > scanner. So if you know exactly where it is, it > seems it would be as > easy to remove as to implant. And I can't imagine > people consenting to > serious surgery for implant -- it would have to be > just sub-cutaneous in order to be widely adopted.
It can be surprisingly difficult to identify tiny foreign bodies that have been encapsulated; "walling off the invader" is one of the body's responses to almost any chronic foreign body (even "inert" matter such as silicon usually causes some scar tissue formation). If the scanner isn't very precise (and I have no idea what its resolution is), one might have to make a number of triangulation measurements to identify _which_ little lump is the chip, especially if it migrated interiorly rather than externally. Even with our current level of sophistication WRT imaging modalities, surgeons frequently have to adapt their planned course once the body is opened. (Bob Z would know more about that.) Animal microchips are visible on X-ray films; apparently they are _not_ usually supposed to be palpable on physical exam (unless an abcess has formed). There are scanning systems that can 'read' the chips in migrating fish (I don't know the specs/distances involved, but if the fish must pass through a 'ladder' in a dam, it might be just inches); work on a 'walk-though' scanner for dogs/cats is being done, but I don't know if it's available yet - the SPCA site might have something. While I'm not a surgeon, I do have a little experience with externally-migrating foreign bodies (usually sutures, in my case). Foreign bodies under the skin are well-known to extravasate or 'break out;' the person thinks they have a lump or new mole, then it abcesses and becomes identifiable as suture material (blue or black color usually). While we're talking about SQ implants, it is interesting that deep foreign bodies can migrate even across barrier muscle or through an organ, as happened to this patient: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12027209&dopt=Abstract "...This report describes the case of a 60-year-old Japanese man with jaundice caused by an impacted shrapnel splinter in the common bile duct (CBD) that had migrated from the right thoracic cavity 36 years after initial injury...It was serially documented that the shrapnel had migrated toward the diaphragm, then burrowed into the liver, settling in the CBD, and causing obstructive jaundice..." And here are cases of buckshot to the abdomen winding up passing through the ureter. (Ouch! Many people say that passing a kidney stone is as painful as birth labor; imagine passing buckshot! Shrapnel or bullets have to be surgically removed, as they are too large or too irregular to be passsed, and of course cannot be 'shattered' as some natural renal 'stones' can be with extracorporeal shockwave lithotripsy.) http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7500418&dopt=Abstract Click on the "Related Articles," and you'll find cases of shot/shrapnel eroding into blood vessels and causing varied problems like stroke or coughing up blood etc. Some of these objects wind up moving over a foot! After 16 weeks, this veterinary study found that ~ half the transponders implanted around the shoulder area of dogs had migrated somewhat (those in the head hadn't moved); almost all already had been encapsulated: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10530881&dopt=Abstract One out of 33 dogs in this tiny study had to be scanned (I presume they meant X-ray) and carefully examined to find the microchip after one year: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7657580&dopt=Abstract Unfortunately, most of the articles about migrating microchips in animals don't have available abstracts (just click on 'Related Articles'). :P This company claims to have "non-migrating microchip technology," but I couldn't find any specs upon scanning the site: http://www.identipet.com/qafrm.htm > Anything that is swallowed is unlikely to be > permanent enough. Yes; in fact there is a 'swallowable camera' for (limited) examination of the small bowel, most of which is not accessible via endoscopy. But I can envision a day when, with nanotechnology, one could engineer 'nanobots' that could be put in someone's food, and with the proper trigger (say, the higher pH that occurs once stomach acid is neutralized by bile, as food passes into the small intestine), activate and attach/penetrate the gut lining. Debbi __________________________________ Do you Yahoo!? The New Yahoo! Shopping - with improved product search http://shopping.yahoo.com _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
