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From: TSS ()
In Reply to: FDA 50 STATE EMERGENCY BSE CONFERENCE CALL JANUARY 9, 2001 posted by TSS on October 31, 2006 at 4:57 pm:
CORRECT AS OF 21ST SEPTEMBER 2006 17 Medical Implants Containing Bovine Material At SEAC 91 (February 2006) the Medicines and Healthcare products Regulatory Agency (MHRA) asked the committee to consider the potential BSE risks to humans from medical implants using bovine material from the USA. The regulations on medical devices containing animal materials are based on the principle that TSE risks must be eliminated or reduced as much as possible and residual risks must be acceptable when weighed against the benefits to patients. Currently no guidance exists on the acceptability of TSE risk control measures applied to animal material in medical devices. The MHRA requested advice on three 3 issues. (i) can TSE risk associated with medical implants using USA sourced bovine material be estimated given that it might vary over time? (ii) is there, or has there been a significant risk that might warrant action in addition to that already taken? (iii) can the standards that support the regulations be altered to facilitate a consistent approach about the acceptability of products? The committee concluded that: • a risk assessment should be conducted on each device because of the large number of variables that influence associated TSE risks. Key factors which should be considered when assessing risks are: • the animal source. Use of material from closed herds or from herds that are managed carefully to prevent the introduction of the BSE agent. • use of material from young animals would markedly lower risk compared with older animals. • the geographical risk of BSE. The geographical BSE risk status of a country gives an imprecise indication of BSE risk. It would be better to use an estimated prevalence of BSE in a country based on data from a robust surveillance system. • the potential TSE infectivity of the source tissue(s) based on a careful assessment of the available data on tissue infectivity. CORRECT AS OF 21ST SEPTEMBER 2006 18 • the site of implantation. Sites with contact with the blood supply or CNS may increase risk. • whether TSE testing is undertaken on the source animal(s). • the number of source animals used for each device. 44 Conformation-dependent immunoassay (CDI) for abnormal prions At SEAC 88 (June 2005), SEAC commented on a recent paper11 which had reported that the conformation-dependent immunoassay (CDI) for abnormal prions was more sensitive than other biochemical tests. The committee: • commented that, unlike most biochemical tests, it did not rely on proteinase K (PK) digestion of prions and could detect PK sensitive forms of abnormal prions. • expressed caution about the assumption that the test was capable of measuring the infectious agent, as the form of prion constituting the infectious agent was still unclear. 11 Safar et al. (2005) Diagnosis of human prion disease. Proc. Natl. Acad. Sci. U S A. 102, 3501-3506. incidence of CJD in various countries, other than the UK, indicates that there is no obvious decline in the numbers of cases being reported. However, in the UK there seems to have been a steady decline in the number of suspected cases, and therefore of confirmed cases, for the past several years. He asked 3 questions: (i) What are the causes of the decline in the number of suspected cases reported in the UK over the past few years? (ii) What is the effect of this decline in reports of suspected cases on the certainty of the decline of the number of new cases of vCJD reported in the UK? (iii) What is the effect of this decline in reports of suspected cases on the certainty that new cases of iatrogenic transmission of CJD and/or vCJD could be identified? 6. Professor Ironside commented that the number of suspected cases of sCJD reported each year had varied since surveillance began, but numbers had appeared to decline in the past 2 years. However, this was unlikely to be due to significant numbers of cases being missed. As a way of checking to see if cases had been missed, NCJDSU had looked back at diagnosed cases of atypical dementia but had not identified any cases of CJD. The recent decrease in numbers of suspected cases reported was therefore probably due to improvements in clinical diagnostic criteria and the resultant improved quality of referrals. NCJDSU had very good links with clinicians and pathologists across the UK. I find this interesting ; (i) What are the causes of the decline in the number of suspected cases reported in the UK over the past few years? the certainty of the decline of the number of new cases of vCJD reported in the UK? either variant CJD-like or sporadic CJD Date: Thu, 28 Nov 2002 10:23:43 -0000 From: "Asante, Emmanuel A" To: Dear Terry, I have been asked by Professor Collinge to respond to your request. I am a Senior Scientist in the MRC Prion Unit and the lead author on the paper. I have attached a pdf copy of the paper for your attention. Thank you for your interest in the paper. In respect of your first question, the simple answer is, yes. As you will find in the paper, we have managed to associate the alternate phenotype to type 2 PrPSc, the commonest sporadic CJD. It is too early to be able to claim any further sub-classification in respect of Heidenhain variant CJD or Vicky Rimmer's version. It will take further studies, which are on-going, to establish if there are sub-types to our initial finding which we are now reporting. The main point of the paper is that, as well as leading to the expected new variant CJD phenotype, BSE transmission to the 129-methionine genotype can lead to an alternate phenotype which is indistinguishable from type 2 PrPSc. can be of any further assistance please to not hesitate to ask. Best wishes. <> ____________________________________ Dr. Emmanuel A Asante MRC Prion Unit & Neurogenetics Dept. Imperial College School of Medicine (St. Mary's) Norfolk Place, LONDON W2 1PG Tel: +44 (0)20 7594 3794 Fax: +44 (0)20 7706 3272 email: e.asante@ic.ac.uk (until 9/12/02) New e-mail: e.asante@prion.ucl.ac.uk (active from now) ____________________________________ snip... full text ; http://www.fda.gov/ohrms/dockets/ac/03/slides/3923s1_OPH.htm http://www.bseinquiry.gov.uk/files/yb/1988/11/04003001.pdf http://www.bseinquiry.gov.uk/files/yb/1989/02/14010001.pdf although 176 products do _not_ conform to the CSM/VPC http://www.bseinquiry.gov.uk/files/yb/1989/09/06011001.pdf Terry S. Singeltary Sr.
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