DNAunion

DNAunion: I think what someone said above is correct. Basically, prions are altered forms of a normal protein which can exist in two stable conformations. When an infective form of that protein comes into contact with a normal form of that protein, it can cause a conformational change in the normal form converting it into a prion (I've never actually studied prions, by the way).

Assuming that is correct, then no, a prion cannot convert another kind of protein - like actin or myosin - into a prion: the to-be-converted protein must be the same protein, just in a different stable shape. Also, prions would not be self-replicators (they'd be "converters").

Doubting Didymus

Gotcha, so foot in mouth must be caused by prion infection in the proteins of only one specific type in the cells of the cow. Sounds like prions don't satisfy differential replication efficacy.

I should point out that the fact that they are not SELF replicators would not have mattered, had prion microspheres been a viable hypothesis. The prions could be good enough for abiogenesis given only the raw material to concert, and that would be where the microspheres come in. However, the hypothsis fails on other grounds before we even get that far. Never mind.

RufusAtticus

The normal proteins are called PrPc (Prion Protein Cellular). (I'd just rather call the whole lot prions. Not just the pathogenic variants.)

From here.

DNAunion

DNAunion: Just want to point out that it is PROTEINOID microspheres that were asked about, not PRION microspheres. Prions are proteins whereas proteinoids are not.

Doubting Didymus

I know, but your comments about 'not being self replicating' were about prions. That's all I was adressing.

Fiach

PRIONS are fascinating proteinaceous spheres that require a DNA alteration of alleles that take a precursor to the PRION disease causing protein that either can be inherited or PRIONS themselves transmitted to other animals including humans (Libyan goats, cattle, mink, and humans.) Here are three article abstracts that include URLs to the full article text for those who feel comfortable with chemical and genetic terminology.

Decreased ß-amyloid1-42 in cerebrospinal fluid of patients with Creutzfeldt-Jakob disease

http://www.neurology.org/cgi/content...code=neurology

M. Otto, MD, H. Esselmann, PhD, W. Schulz-Schaeffer, MD, M. Neumann, MD, A. Schröter, MD, P. Ratzka, MD, L. Cepek, MD, I. Zerr, MD, P. Steinacker, PhD, O. Windl, PhD, J. Kornhuber, MD, H. A. Kretzschmar, MD, S. Poser, MD and J. Wiltfang, MD
From the Neurologische Klinik und Poliklinik (Drs. Otto, Schrôter, Ratzka, Cepek, Zerr, Steinacker, and Poser) and Psychiatrische Klinik und Poliklinik (Drs. Esselmann, Kornhuber, and Wiltfang), Institut für Neuropathologie (Drs. Schulz-Schaeffer, Neumann, Windl, and Kretzschmar), Georg-August-Universität Göttingen, Germany.

Address correspondence and reprint requests to Dr. Markus Otto, Neurologische Klinik und Poliklinik, Universität Göttingen, Robert-Koch Str. 40, 37070 Göttingen, Germany; e-mail: motto@gwdg.de

OBJECTIVES: Decreased levels of Aß1-42 are found in CSF of patients with AD. Because early stages of Creutzfeldt-Jakob disease (CJD) and AD share several clinical features, we investigated Aß1-42 levels in CSF of these groups, inferring that this might give additional help in differentiating patients with CJD from AD patients.

METHODS: We investigated 27 patients with CJD, 14 patients with AD, 19 patients with other dementias, and 20 nondemented controls (NDC) for Aß1-42 in CSF. Twenty-four of the 27 CJD patients were neuropathologically verified. All the neuropathologically verified patients presented with a type 1 prion protein pattern. CJD patients were all homozygous for methionine at codon 129. Except in five CJD patients, no ß-amyloid plaques were seen. Additionally, APOE status was determined in patients with CJD.

RESULTS: Levels of Aß1-42 in CSF were decreased in patients with AD as well as in CJD. Levels of Aß1-42 in CSF of patients with CJD and AD were significantly different from the other dementia and NDC groups. There was no substantial difference between the CJD and AD groups (p = 0.66). Decreased levels of Aß1-42 did not correlate with the APOE 4 load in patients with CJD.

CONCLUSION: Low levels of Aß1-42 in CSF do not exclude a diagnosis of CJD. Decreased levels of Aß1-42 in CSF can occur without ß-amyloid plaque formation in the brain. However, the underlying mechanism of this phenomenon must be elucidated.

Key words: Creutzfeldt-Jakob disease—AD—Aß1-42—APOE allele—Protein 14-3-3—Amyloid beta—Laboratory diagnosis.

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Two-octapeptide repeat deletion of prion protein associated with rapidly progressive dementia

http://www.neurology.org/cgi/content...code=neurology

J.A. Beck, BSc;, S. Mead, MRCP;, T.A. Campbell, BSc;, A. Dickinson, BSc;, D.P.M.W. Wientjens, MD;, E.A. Croes, MD;, C.M. Van Duijn, PhD and J. Collinge, FRCP

From the MRC Prion Unit, Department of Neurogenetics (Drs. Beck, Mead, Campbell, Dickenson, and Collinge), Imperial College School of Medicine at St. Mary’s, London, UK; and Department of Epidemiology and Biostatistics (Drs. Wientjens, Croes, and Duijn), Erasmus Medical Centre, Rotterdam, The Netherlands.

Address correspondence and reprint requests to Dr. John Collinge, Department of Neurogenetics, Imperial College School of Medicine at St. Mary’s, Norfolk Place, London, W2 1PG, UK; e-mail: j.collinge@ic.ac.uk

"Insertions of integral numbers of an octapeptide repeat in the prion protein gene are pathogenic mutations associated with inherited prion diseases. Conversely, deletions of a single octapeptide repeat are found as normal polymorphisms in many populations and do not predispose individuals to prion disease. The authors report a two-octapeptide repeat deletion in an elderly woman with a rapidly progressive dementia consistent with Creutzfeldt-Jakob disease. This mutation was absent from more than 3,000 individuals and may be causally related to prion disease and represent a novel disease mechanism."

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Drug therapy in human and experimental transmissible spongiform encephalopathy

http://www.neurology.org/cgi/content...code=neurology

Paul Brown, MD

From the Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD.

Address correspondence and reprint requests to Dr. Paul Brown, Building 36, Room 4A-19 (MSC-4123), National Institutes of Health, Bethesda, MD 20892-4122; e-mail: brownp@ninds.nih.gov

During the past 30 years, over 60 different chemical compounds have been used to treat experimental animals infected with transmissible spongiform encephalopathies (TSE), including a wide variety of anti-infectious agents, immunomodulating drugs, and chemicals interacting with the lympho-reticular system. Some compounds achieved a prolongation of the incubation period, but this effect decreased or disappeared when they were administered at or near the onset of symptomatic disease.

Recent in vitro and tissue culture studies support earlier speculation about the importance of a chemical structure containing both water-soluble and lipid-soluble components, evidently as a means of interaction with the misfolded membrane-bound ‘prion’ protein. A number of compounds shown to eliminate the protein (or infectivity) in TSE-infected tissue cultures are the subject of ongoing studies in animals, and are under consideration for human drug trials.

As with other recalcitrant infections, combinations of drugs with different modes of action are likely to be necessary for any effective therapy. Also, very recent work in developing antibodies that can neutralize in vitro infection (and, in conjunction with genetic engineering, in vivo infection) has renewed interest in the strategies of both active and passive immunization.

(Fiach: remember these are abstracts from Neurology, the Journal. If you go to the URL's you can retrieve the full texts.

Thanatoast

Jobar said:
The information given, and arguments over, such topics as prions and microsheres is fascinating. However, I'm quite surprised no one has mentioned the simple fact that biological evolution, in and of itself, merely denotes "change over time".

Whether or not Jobar mentioned this to his creationist friend in his conversation, he doesn't mention. But I would think this is a crucial point to make before discussing the minutiae of abiogenesis research with one who believes that the Book of Genesis is the "Literal Truth".

DNAunion

DNAunion: So when my cars' tires change over time as the tread is worn from driving, that's biological evolution?

pz

Your tires replicate? Cool trick.

DNAunion

DNAunion: The person I was responding to said nothing about biological evolution involving replication; simply "change over time".

Since he did say biological evolution, we can assume biology is involved, changing his statement to "biological change over time". But then is my skin undergoing biological evolution as it gets more wrinkled as I age?