The aim of the investigation was to test the reproducibility and accuracy of a new method to measure temporomandibular joint (TMJ) fluid concentrations of various substances by saline washing, using exogenous B12 as a marker. An in vitro test was first performed with glucose as a test substance. The difference between a B12-calculated and known standard concentration of glucose was very small. Saline washing of the TMJ was performed on 13 patients having signs of TMJ arthritis, and the aspirates obtained were analyzed for neuropeptide Y-like immunoreactivity (NPY-LI) and interleukin-1 beta (IL-1 beta). Vitamin B12 was mixed with the saline immediately before injection, and a sample of the aspirate was later compared photometrically with the injection solution. There were positive correlations between saline aspirate and joint fluid concentrations for NPY-LI and IL-1 beta, and the correlations were stronger for saline aspirates with high joint fluid content. This study shows that the method is reliable for measurement of joint fluid concentrations of various substances, such as NPY-LI and IL-1 beta.
Abstract— There is evidence that neuropeptides play a role in the development of arthritis. Synovial fluid from arthritic temporomandibular joints in patients with rheumatoid arthritis was therefore investigated for presence of the neuropeptides calcitonin gene‐related peptide, substance P, neurokinin A and neuropeptide Y. All four peptides were found in the synovial fluid above plasma level, but calcitonin gene‐related peptide showed the highest concentration and substance P the lowest.
Twenty-two patients (29 joints) with temporomandibular joint (TMJ) arthritis of specific or unspecific nature were given one intra-articular glucocorticoid (GC) injection. The effect on subjective symptoms and clinical signs in the craniomandibular system and on joint aspirate concentration of neuropeptide Y-like immunoreactivity (NPY-LI) was evaluated at follow-up visits 2-3 or 4-6 weeks after treatment. In the patients with specific inflammatory joint disease the treatment resulted in an improvement of symptoms and clinical signs and in a reduction in the TMJ level of NPY-LI 2-3 weeks after treatment. In the patients with unspecific inflammatory joint disease there was also an improvement in the clinical variables and a reduction in the NPY-LI level after 2-3 weeks, but not on a statistically significant level. The results of this study show that intra-articular GC treatment causes a short-term decrease of the TMJ fluid level of NPY-LI in patients with specific inflammatory joint disease, while symptoms and signs improve.
The amount of synovial fluid in small joints which is available for analysis of endogenous compounds is usually very limited and saline washings are therefore commonly required. However, since the washing fluid is not fully recovered and, furthermore, dilutes the synovial fluid in the joint aspirate, the true synovial fluid concentration of a particular substance is unknown. In the present study we validate the use of vitamin B12 (hydroxocobalamin, 1 mg ml-1) as an internal standard to determine this dilution, since its strong red colour lends itself to spectroscopic measurement by a capillary tube system requiring only 3 microliter per sample. The absorbance of different dilutions of the stock solutions (25, 33 and 50% vitamin B12 in saline) by saline, plasma and hyaluronan was measured in order to establish the optimal wavelength, the lower limit of detection and the interference by plasma or hyaluronan in the absorbance. Furthermore, the interaction of vitamin B12 in the analyses of interleukin-1 beta, serotonin and glucose was investigated. The optimal wavelength was found to be 350 nm and the limit of detection 0.5-0.9% dilution of the vitamin B12 solution. Hyaluronan or plasma did not influence the absorbance measurements and the minute interaction of vitamin B12 in the photometric measurements could be compensated for.
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