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M9650438.TXT
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1996-03-09
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Document 0438
DOCN M9650438
TI PCR in situ: aspects which reduce amplification and generate
false-positive results.
DT 9605
AU Teo IA; Shaunak S; Department of Infectious Diseases, Royal Postgraduate
Medical; School, London, UK.
SO Histochem J. 1995 Sep;27(9):660-9. Unique Identifier : AIDSLINE
MED/96121506
AB PCR in situ promises the ability to amplify and detect very low levels
of target nucleic acid in tissues. Despite considerable effort, the
technique is still technically difficult and has not yet proved to be
reliable or reproducible. We have now identified a number of factors
which can contribute to the poor amplification of the target DNA and to
the generation of false-positive signals. These factors include the
effects of fixation, reagent abstraction, DNA degradation, DNA
end-labelling and product diffusion. We present evidence to show that
formaldehyde fixation cross-links histones to DNA and thus restricts the
subsequent amplification of target sequences by PCR. End-labelling of
DNA occurs when direct incorporation is used to detect amplified
products and this gives rise to false-positive signals. Amplified
products can also diffuse out of cells and into neighbouring cells which
do not contain target sequences. They can undergo re-amplification
within these cells giving rise to false-positive signals. We believe
considerable caution should be exercised in the interpretation of
results generated using PCR in situ.
DE Autoradiography Base Sequence Blotting, Southern Cell Line
Cross-Linking Reagents DNA Damage DNA, Viral/ANALYSIS
Electrophoresis, Agar Gel False Positive Reactions Formaldehyde Gene
Amplification Histones/CHEMISTRY Human HIV
Infections/DIAGNOSIS/VIROLOGY HIV-1/GENETICS/ISOLATION & PURIF In Situ
Hybridization/*METHODS Molecular Sequence Data Polymerase Chain
Reaction/*METHODS Support, Non-U.S. Gov't Tissue Fixation JOURNAL
ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).