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An autoradiograph is an image on an x-ray film or nuclear emulsion produced by the pattern of decay emissions (e.g., beta particles or gamma rays) from a distribution of a radioactive substance. Alternatively, the autoradiograph can also be available as a digital image (digital autoradiography), thanks to the recent development of scintillation gas detectors1 or rare earth phosphorimaging systems2. In biology, this technique may be used to determine the tissue localization of a radioactive substance, either introduced into a metabolic pathway, bound to a receptor34 or enzyme, or hybridized to a nucleic acid5. The film or emulsion is apposed to the labeled tissue section to obtain the autoradiograph (also called an autoradiogram). The auto- prefix indicates that the radioactive substance is within the sample, as distinguished from the case of historadiography or microradiography, in which the sample is X-rayed using an external source.
The use of radiolabeled ligands to determine the tissue distributions of receptors is termed either in vivo or in vitro receptor autoradiography if the ligand is administered into the circulation (with subsequent tissue removal and sectioning) or applied to the tissue sections, respectively. The ligands are generally labeled with 3H (tritium) or 125I. The distribution of RNA transcripts in tissue sections by the use of radiolabeled, complementary oligonucleotides or ribonucleic acids ("riboprobes") is called in situ hybridization histochemistry. RNA or DNA viral sequences can also be located in this fashion. These probes are usually labeled with 32P, 33P, or 35S.
This autoradiographic approach contrasts to techniques such as PET and SPECT where the exact 3-dimensional localization of the radiation source is provided by careful use of coincidence counting, gamma counters and other devices.
References
- ^ Barthe N, Coulon P, Hennion C, Ducassou D, Basse-Cathalinat B, Charpak G (May 1999). "Optimization of a new scintillation gas detector used to localize electrons emitted by 99mTc". J Nucl Med. 40 (5): 868–75. PMID 10319763, http://jnm.snmjournals.org/cgi/pmidlookup?view=long&pmid=10319763.
- ^ Encyclopedia of Life Sciences: Phosphorimager
- ^ Kuhar M, Yamamura HI (Jul 1976). "Localization of cholinergic muscarinic receptors in rat brain by light microscopic radioautography". Brain Res. 110 (2): 229–43. PMID 938940.
- ^ Young WS, Kuhar MJ (Dec 1979). "A new method for receptor autoradiography: [3H]opioid receptors in rat brain". Brain Res. 179 (2): 255–70. PMID 228806.
- ^ Jin L, Lloyd RV (1997). "In situ hybridization: methods and applications". J Clin Lab Anal. 11 (1): 2–9. doi:. PMID 9021518.
Additional References
- Rogers, Andrew W (1979). Techniques of Autoradiography, 3rd ed., New York: Elsevier North Holland. ISBN 0444800638.
Wikipedia content modification information:
- This page was last modified on 16 November 2008, at 08:55.
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