Serum carboxymethyllysine concentration is associated with erosive hand osteoarthritis.

OBJECTIVE: Carboxymethyllysine (CML) and homocitrulline (HCit) are the products of two non-enzymatic post-translational modifications of protein, a process related to age. We investigated whether serum CML and HCit concentrations were associated with hand osteoarthritis (HOA), especially erosive HOA. DESIGN: Serum CML and HCit were measured by using liquid chromatography coupled with tandem mass spectrometry at inclusion in 386 patients included in the DIGItal Cohort Design (DIGICOD) cohort. We investigated whether serum CML and/or HCit concentrations were associated with erosive HOA or with HOA clinical and radiological features. Moreover, we compared the tissular concentrations of CML and HCit in OA and non-OA cartilage from proximal interphalangeal and metacarpo-phalangeal (MCP) joints from human cadaveric donors. RESULTS: Median (IQR) serum CML concentration was lower in patients with erosive HOA than those with non-erosive HOA (178.7 [157.1-208.8] vs 194.7 [168.9-217.1] µmol/mol Lys, P = 0.002), but median HCit concentration did not differ between the groups (193.9 [162.9-232.0] vs 193.9 [155.9-224.6] µmol/mol Lys). Cartilage HCit and CML concentrations were not correlated with clinical features. Serum CML concentration was higher in OA than non-OA MCPs (7.0 vs 4.0 mmol/mol Lys, P = 0.01). CONCLUSIONS: Serum CML concentration was lower in erosive HOA than non-erosive HOA, and cartilage CML concentration was higher in OA than non-OA cartilage. These results encourage further studies to test whether serum CML could be a new prognostic biomarker in HOA.

Simultaneous detection of indoleamines and dopamine in rat dorsal raphe nuclei using specific antibodies.

Using a monoclonal antibody against dopamine and a rabbit antiserum against serotonin, 5-methoxytryptamine or tryptamine, we were able to achieve the simultaneous localization of two amines in glutaraldehyde-fixed sections of rat dorsal raphe nuclei. In this staining procedure, the first antigen was localized using 3,3'-diaminobenzidine (DAB), while the second antigen was stained using the 1-naphthol basic dye (2-NBD) method. The two antigens were localized in different cells or structures. No overlap of the staining was observed, thus indicating that dopamine is not localized with serotonin, 5-methoxytryptamine or tryptamine.

Monoclonal antibodies against glutaraldehyde-conjugated dopamine.

Four mice were immunized with dopamine (DA)-glutaraldehyde (G)--protein conjugates over a period of 8-10 weeks. Polyclonal antisera, obtained at various intervals, were tested using an enzyme-linked immunosorbent assay (ELISA). All had anti-conjugated DA antibodies. As soon as good antibody affinity was detected between 10(-10) and 10(-6) M, the mouse yielding the highest apparent affinity was killed, and the spleen was dissected out. Hybridomas were obtained from spleen cells fused with SP2/O/Ag myeloma cells. Supernatant culture media of hybridomas were tested for the presence of anti-conjugated DA antibodies with the ELISA method. Selected hybridomas giving good antibody affinity and specificity were then cloned by the limiting dilution technique. The resulting supernatant culture media were again tested by ELISA. Clones that gave a high antibody affinity (10(-10)-10(-8)M) for G-conjugated DA were used for histochemical localization of DA in rat brain. G-fixed rat brains were sectioned from the telencephalon to the mesencephalon, reduced with sodium borohydride, and prepared for peroxidase-antiperoxidase immunocytochemistry using supernatant (diluted 1:100) or ascites fluid (diluted 1:50,000). Dense networks of very fine fibers were observed in the striatum, septum, and cortex. Numerous immunoreactive cell bodies were found in the ventral tegmental area, the substantia nigra, the hypothalamus, and the dorsal raphe. The ELISA tests and adsorption controls suggested that the monoclonal antibody allowed highly specific detection of DA in tissues.

Effects of 100 mT time varying magnetic fields on the growth of tumors in mice.

The effects of 100-mT, 0.8-Hz square-wave magnetic fields on the growth of chemically induced tumors in mice were investigated. Tumors were initiated using one injection of benzo(a)pyrene (either 0.2 mg or 2.0 mg/animal). Male and female mice (Balb/c, C3H and C57/bl/6 strains) were exposed for 8 h/day from the onset of tumor until death or until the tumor volume reached a predetermined volume. Statistically significant decrease in the rate of tumor growth and increase in survival were observed in all cases. Results are discussed in terms of previous published work and of possible mechanisms.

Potassium channel inhibition reduces cell proliferation in the GH3 pituitary cell line.

Potassium (K+) conductances are known to be involved in cell proliferation of a number of nonexcitable cell types. The nature of the mechanism by which K+ channel inhibition reduces cell proliferation has remained elusive despite intensive search. We investigated whether such a phenomenon could be demonstrated in excitable cells, using the GH3 pituitary cell line as a cell model. Our aims were: 1) to study the effect of K+ channel inhibition on the proliferation of GH3 cells; and 2) to investigate the putative intracellular signals involved in this inhibition. Tetraethylammonium chloride (TEA), a blocker of the calcium (Ca2+)-dependent K+ conductances of GH3, was found to reversibly inhibit cell proliferation, as measured by 3H-thymidine incorporation. Cell cycle block specifically occurred at the G1/S phase of the cell cycle. This inhibition of proliferation was observed for 1-4 mM TEA, which suppressed most of the Ca2+-activated K+ current and part of the inward rectifying K+ current, as shown by electrophysiological experiments. Increasing extracellular K+ concentrations with KCI also inhibited cell proliferation in a dose-dependent manner. Both TEA and KCl depolarized the cells and increased intracellular Ca2+ levels ([Ca2+]i), showing that, in this type of excitable cell, inhibition of cell proliferation can be associated with elevated Ca2+ levels. Ca2+ and membrane resting potential (MRP) were considered as possible messengers of this inhibition. Our results suggest that cell cycle arrest of GH3 cells by K+ channel block probably involves an additional pathway, distinct from those of Ca2+ and MRP.

Effects of time-varying uniform magnetic fields on natural killer cell activity and antibody response in mice.

Natural Killer cell activity and antibody response were studied in Balb/c mice which were exposed in vivo to uniform pulsed magnetic fields (square-wave, 0.8 Hz, 120 mT maximum field strength, 0.1 s rise-time) for 5 days, 10 h/day. No effects were found in antibody response to sheep red blood cell (SRBC) immunization as assayed by counting the plaque-forming cells (PFC) in the spleens of animals on the sixth day. Following 5-day exposures, the activity of Natural Killer (NK) cells was measured in vitro by challenge with YAC-1 cells, in experiments in which mice were not immunized. An increase of NK cytotoxic activity due to exposure was found which depended on the age of the mice (effect observed above 12 weeks) and on the strength of the applied field (effect observed above 30 mT).