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Autoxidation of polyunsaturated fatty acids (PUFAs) damages lipid membranes and generates numerous toxic by-products implicated in neurodegeneration, aging, and other pathologies. Abstraction of bis-allylic hydrogen atoms is the rate-limiting step of PUFA autoxidation, which is inhibited by replacing bis-allylic hydrogens with deuterium atoms (D-PUFAs). In cells, the presence of a relatively small fraction of D-PUFAs among natural PUFAs is sufficient to effectively inhibit lipid peroxidation (LPO). Here, we investigate the effect of various D-PUFAs on the stability of liposomes under oxidative stress conditions. The permeability of vesicle membranes to fluorescent dyes was measured as a proxy for bilayer integrity, and the formation of conjugated dienes was monitored as a proxy for LPO. Remarkably, both approaches reveal a similar threshold for the protective effect of D-PUFAs in liposomes. We show that protection rendered by D-PUFAs depends on the structure of the deuterated fatty acid. Our findings suggest that protection of PUFAs against autoxidation depends on the total level of deuterated bi-sallylic (CD 2 ) groups present in the lipid bilayer. However, the phospholipid containing 6,6,9,9,12,12,15,15,18,18-d 10 -docosahexaenoic acid exerts a stronger protective effect than should be expected from its deuteration level. These findings further support the application of D-PUFAs as preventive/therapeutic agents in numerous pathologies that involve LPO., (© 2019 Federation of European Biochemical Societies.)

The clinical significance of the histomorphological evaluation of synovial tissue from 389 patients with joint diseases was studied. From these data we conclude: (1) the histomorphological diagnosis in joint diseases is rarely of decisive value (6.2%); (2) in 23.1% of cases the histomorphological diagnosis is judged to be of clinical assistance; (3) the histomorphological grading of the inflammatory reaction in the joint under study corresponds in approximately two out of three cases to the clinical judgement.

Immunophotometrical measurements of the Ig synthesis of plasma cells in joint capsules of patients with rheumatoid arthritis and osteoarthritis were compared. Patients with rheumatoid arthritis showed higher mean values in the single plasma cell than patients with osteoarthritis for all Ig isotypes except IgG. These results are indicative for a B cell activation with increased synthesis of Ig in RA.

The amount of extravascular immunoglobulin deposits in the synovial membrane of patients with osteoarthritis and rheumatoid arthritis was studied in comparison with that of patients suffering from non-joint diseases. Immunoglobulin deposits were immunostained using the three-layer immunoperoxidase method. The staining results were quantified with the help of a microscope photometer connected with a scanning stage. Several experiments involving artificial test substrates, diseases with allegedly increased extravascular deposits or diseases not exhibiting extravascular deposits of immunoglobulins are used to validate the described microspectrophotometrical approach for measuring extravascular immunoglobulin deposits. The scanning photometry demonstrates significantly higher amount of extravascular immunoglobulin deposits in rheumatoid arthritis as compared with osteoarthritis and non-joint diseases.