Proceedings of the Irish Soc for Rheumatology and Irish - IJMS | Irish ...
Proceedings of the Irish Soc for Rheumatology and Irish - IJMS | Irish ...
Proceedings of the Irish Soc for Rheumatology and Irish - IJMS | Irish ...
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<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Irish</strong> <strong>Soc</strong> <strong>for</strong> <strong>Rheumatology</strong> <strong>and</strong> <strong>Irish</strong> <strong>Rheumatology</strong> Health<br />
Pr<strong>of</strong>essionals <strong>Soc</strong>iety AGM September 2006<br />
8. DETECTION OF SYNOVIAL FLUID CALCIUM PHOSPHATE<br />
CRYSTALS: A ROUTE TO IMPROVED DIAGNOSIS AND<br />
CHARACTERISATION OF OSTEOARTHRITIS<br />
G.P. McMahon 1 , R. Kilkenny 1 , K. Behan 1 , D.A. Smith 2 , G.M. McCarthy 3<br />
1 Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Irel<strong>and</strong>,<br />
2 Physics <strong>and</strong> Astronomy, University <strong>of</strong> Leeds, Leeds, LS2 9JT, Engl<strong>and</strong>,<br />
3 Molecular <strong>and</strong> Cellular Therapeutics, Royal College <strong>of</strong> Surgeons in Irel<strong>and</strong>,<br />
123 St. Stephen’s Green, Dublin 2, Irel<strong>and</strong><br />
Basic calcium phosphate (BCP) crystals are found in up to 70% <strong>of</strong> OA joints.<br />
Current data suggest that intra-articular (IA) BCP crystals represent a potential<br />
<strong>the</strong>rapeutic target in OA. However, no simple test <strong>for</strong> IA BCP crystals is<br />
currently available.<br />
Aim: To devise a sensitive <strong>and</strong> specific method to detect <strong>and</strong> quantify BCP<br />
crystals in OA synovial fluid (SF) samples.<br />
Methods:<br />
• Colorimetric analysis <strong>of</strong> SF based on dyes i.e. alizarin test <strong>for</strong> calcium<br />
(red), molybdate test <strong>for</strong> phosphate (blue), Gomorri’s silver test <strong>for</strong> urate<br />
(black) <strong>and</strong> Yasue’s test <strong>for</strong> oxalate (grey).<br />
• Atomic <strong>for</strong>ce microscopy (AFM) in tapping mode <strong>for</strong> imaging <strong>of</strong> <strong>the</strong> submicrometer<br />
size BCP in SF.<br />
• Raman spectroscopy using a source laser at 785nm which uses a unique<br />
peak 960cm -1 as a marker <strong>for</strong> SF BCP.<br />
• SF was obtained from knee joints from patients with moderate or severe<br />
OA.<br />
Results: Colorimetric testing has detected <strong>the</strong> presence <strong>of</strong> BCP in SF, <strong>and</strong> can<br />
distinguish between BCP, calcium pyrophosphate dihydrate (CPPD) <strong>and</strong> o<strong>the</strong>r<br />
crystals.<br />
Preliminary AFM results have shown <strong>the</strong> presence <strong>of</strong> small spheroids <strong>of</strong><br />
inorganic-like material <strong>of</strong> <strong>the</strong> nanometer size expected <strong>of</strong> BCP crystals in<br />
samples from patients with severe OA which are not seen in control SF.<br />
Raman spectral data obtained from SF samples indicates that 960cm -1 is<br />
unique to BCP, 1043cm -1 is unique to CPPD <strong>and</strong> 1068cm -1 is unique to urate<br />
crystals.<br />
Conclusions: All three approaches <strong>of</strong>fer potential as a simple objective<br />
diagnostic test <strong>for</strong> BCP crystals in OA. Colorimetric test-strips <strong>and</strong> portable<br />
Raman would be particularly suited to point-<strong>of</strong>-care <strong>and</strong> in-clinic applications.
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