The effect of pulsed electromagnetic fields on chondrocyte morphology.

Osteoarthritis is a debilitating joint disease where the articular cartilage surface degrades and is unable to repair itself through natural processes. Chondrocytes reside within the cartilage matrix and maintain its structure. We conducted in vitro experiments to investigate the morphological response of cultured human chondrocytes under different pulsed electromagnetic field (PEMF) conditions. In the control experiments, cultured chondrocytes attached to the bottom of a culture dish typically displayed either a stellate or spindle morphology with extended processes. Experimental chondrocyte cultures were placed in a Helmholtz coil to which a ramp waveform was applied. Exposure to PEMFs caused the chondrocytes to retract their processes, becoming spherical in shape. This change in morphology followed a progression from stellate to spindle to spherical. These morphological changes were reflected in an average reduction of 30% in the surface contact area of the chondrocytes to the culture dish. Understanding the mechanisms by which PEMFs affect the morphology of chondrocytes will help lead to new treatments for osteoarthritis.

A rapid and specific radioimmunoassay for methotrexate.

A sensitive and precise radioimmunoassay for methotrexate has been developed using antibody induced in rabbits, tritium-labeled methotrexate, and a nitrocellulose membrane separation technique. Antibody specificity was characterized by comparing the effectiveness of various related compounds to displace labeled methotrexate from the antibody-binding site. Assay of serum samples from persons receiving the drug was rapid and easy to perform. In a pharmacokinetic study of methotrexate, corresponding results were obtained when measurements were made by either enzymic assay or by radioimmunoassay. Drug concentrations could also be monitored in the cerebrospinal fluid and urine of patients on high-dose methotrexate therapy followed by citrovorum factor rescue. The system measured a little as 0.1 to 1 pmole of methotrexate, depending upon the antiserum used, and naturally occurring folates did not interfere with these determinations.