- J Hosp Infect 2002 Jul;51(3):233-5 Related Articles,
Links [Click here to read] Contaminated dental instruments.
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- Smith A, Dickson M, Aitken J, Bagg J.
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- Infection Research Group, Glasgow Dental Hospital &
School, 378 Sauchiehall Street, Glasgow, UK. a.smith@dental.gla.ac.uk
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- There is current concern in the UK over the possible
transmission of prions via contaminated surgical instruments. Some dental
instruments (endodontic files) raise particular concerns by virtue of their
intimate contact with terminal branches of the trigeminal nerve. A visual
assessment using a dissecting light microscope and scanning electron microscopy
of endodontic files after clinical use and subsequent decontamination was
performed. The instruments examined were collected from general dental
practices and from a dental hospital. Seventy-six per cent (22/29) of the
files retrieved from general dental practices remained visibly contaminated,
compared with 14% (5/37) from the dental hospital. Current methods for
decontaminating endodontic instruments used in dentistry may be of an insufficient
standard to completely remove biological material. Improved cleaning methods
and the feasibility of single use endodontic instruments require further
investigation.
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- PMID: 12144804 [PubMed - indexed for MEDLINE]
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- http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve
&db=PubMed&list_uids=12144804&dopt=Abstract
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- J Gen Virol 1999 Nov;80 ( Pt 11):3043-7
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- Transmission of the 263K scrapie strain by the dental
route.
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- Ingrosso L, Pisani F, Pocchiari M
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- Laboratory of Virology, lstituto Superiore di Sanita,
Viale Regina Elena 299, 00161 Rome, Italy.
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- Apart from a few cases of iatrogenic and familial human
transmissible spongiform encephalopathies (TSEs) or prion diseases, the
cause of Creutzfeldt-Jakob disease (CJD) remains unknown. In this paper
we investigated the possibility that dental procedures may represent a
potential route of infection. This was assessed by using the experimental
model of scrapie in hamster. In the first part of this study we found that
after intraperitoneal inoculation, oral tissues commonly involved in dental
procedures (gingival and pulp tissues) bore a substantial level of infectivity.
We also found high scrapie infectivity in the trigeminal ganglia, suggesting
that the scrapie agent had reached the oral tissues through the sensitive
terminal endings of the trigeminal nerves. In the second part of the study
we inoculated a group of hamsters in the tooth pulp and showed that all
of them developed scrapie disease. In these animals, we detected both infectivity
and the pathological prion protein (PrPsc) in the trigeminal ganglion homolateral
to the site of injection but not in the controlateral one. This finding
suggests that the scrapie agent, and likely other TSE agents as well, spreads
from the buccal tissues to the central nervous system through trigeminal
nerves. Although these findings may not apply to humans affected by TSEs,
they do raise concerns about the possible risk of transmitting these disorders
through dental procedures. Particular consideration should be taken in
regard to new variant CJD patients because they may harbour more infectivity
in peripheral tissues than sporadic CJD patients.
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- PMID: 10580068
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- http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10580068&dopt=Abstract
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- a simple auto-claving just will not kill this agent,
considering the fact this agent can survive ashing to 600 degrees celsius;
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- New studies on the heat resistance of hamster-adapted
scrapie agent: Threshold survival after ashing at 600°C suggests an
inorganic template of replication Paul Brown*,dagger , Edward H. RauDagger
, Bruce K. Johnson*, Alfred E. Bacote*, Clarence J. Gibbs Jr.*, and D.
Carleton Gajdusek§
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- * Laboratory of Central Nervous System Studies, National
Institute of Neurological Disorders and Stroke, and Dagger Environmental
Protection Branch, Division of Safety, Office of Research Services, National
Institutes of Health, Bethesda, MD 20892; and § Institut Alfred Fessard,
Centre National de la Recherche Scientifique, 91198 Gif sur Yvette, France
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- Contributed by D. Carleton Gajdusek, December 22, 1999
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- Abstract
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- One-gram samples from a pool of crude brain tissue from
hamsters infected with the 263K strain of hamster-adapted scrapie agent
were placed in covered quartz-glass crucibles and exposed for either 5
or 15 min to dry heat at temperatures ranging from 150°C to 1,000°C.
Residual infectivity in the treated samples was assayed by the intracerebral
inoculation of dilution series into healthy weanling hamsters, which were
observed for 10 months; disease transmissions were verified by Western
blot testing for proteinase-resistant protein in brains from clinically
positive hamsters. Unheated control tissue contained 9.9 log10LD50/g tissue;
after exposure to 150°C, titers equaled or exceeded 6 log10LD50/g,
and after exposure to 300°C, titers equaled or exceeded 4 log10LD50/g.
Exposure to 600°C completely ashed the brain samples, which, when reconstituted
with saline to their original weights, transmitted disease to 5 of 35 inoculated
hamsters. No transmissions occurred after exposure to 1,000°C. These
results suggest that an inorganic molecular template with a decomposition
point near 600°C is capable of nucleating the biological replication
of the scrapie agent.
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- transmissible spongiform encephalopathy | scrapie | prion
| medical waste | incineration
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- Introduction
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- The infectious agents responsible for transmissible spongiform
encephalopathy (TSE) are notoriously resistant to most physical and chemical
methods used for inactivating pathogens, including heat. It has long been
recognized, for example, that boiling is ineffective and that higher temperatures
are most efficient when combined with steam under pressure (i.e., autoclaving).
As a means of decontamination, dry heat is used only at the extremely high
temperatures achieved during incineration, usually in excess of 600°C.
It has been assumed, without proof, that incineration totally inactivates
the agents of TSE, whether of human or animal origin. It also has been
assumed that the replication of these agents is a strictly biological process
(1), although the notion of a "virus" nucleant of an inorganic
molecular cast of the infectious beta -pleated peptide also has been advanced
(2). In this paper, we address these issues by means of dry heat inactivation
studies.
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- see full text:
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- http://www.pnas.org/cgi/content/full/97/7/3418
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- Greetings again,
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- please believe me when i tell you this goes far far beyond
the hamburger/deerburger/elkburger/sheepburger. Pandora's box of the demented
has been opened for decades, closing it will be most impossible with current
safeguards. until they can perfect a test, not only to confirm TSE agent,
but also to differentiate between the many differnt strains (there are
over 20 in sheep scrapie, and sheep scrapie is the sole model for CJD studies),
they then will have to perfect a test that will differentiate between the
many different routes. so, as you can see, this could very well take many
more decades to answer these questions. but in the mean time, i will not
now or ever accept the 'spontaneous/sporadic' theory without any source
and route. i plan to continue to fan the fire until we know what killed
our loved ones...
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- CJD/TSEs MUST BE MADE REPORTABLE NATIONALLY, SUPPORTED
WITH A CJD QUESTIONNAIRE TO EVERY VICTIM/FAMILY THAT ASK REAL QUESTIONS
PERTAINING TO ROUTE/SOURCE...TSS
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- Diagnosis and Reporting of Creutzfeldt-Jakob Disease
T. S. Singeltary, Sr; D. E. Kraemer; R. V. Gibbons, R. C. Holman, E. D.
Belay, L. B. Schonberger
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- http://jama.ama-assn.org/issues/v285n6/ffull/jlt0214-2.html
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- kind regards, terry
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