L. J. Kagen

The goal of these studies was to develop a cost-effective medium for the storage at 22 +/- 2 degrees C of platelets for transfusion. Platelet concentrates were prepared from platelet-rich plasma in a standard fashion and resuspended in 55 mL of medium. Residual plasma was 14.4 +/- 4.3 percent of the final suspending solution. The use of a simple solution containing electrolytes and citrate, but no glucose or bicarbonate, was associated with a drop in pH to the range of 6.0 to 6.6, as a result of the production of lactic acid from the platelet glycogen and glucose present in residual plasma. When 25 mM (25 mmol/L) sodium phosphate was included as a buffer, the drop in pH was retarded, but the range throughout storage was still 6.5 to 6.8. Nonetheless, platelets stored for 5 days in this phosphate-containing medium showed satisfactory maintenance of many in vitro variables. However, there was a 10 to 35 percent reduction of in vivo recovery after isotopic labeling. There was no significant reduction in subsequent mean cell life. Because of the in vivo abnormalities, these media are not recommended for use at the present time. However, the results are encouraging and suggest that further research may lead to a satisfactory, cost-effective medium.

OBJECTIVE: To study the influence of clinical variables on improvement in muscle strength in patients with polymyositis and dermatomyositis. METHODS: We biomechanically examined muscle strength over the course of 2.54 years of 65 patients. RESULTS: Disease duration before therapy was predictive of outcome. Those treated within 6 months or one year of disease onset had better outcomes than those with later treatment. In addition, among those who gained strength, degree of elevation of creatine kinase was correlated with greater gains. CONCLUSION: Early treatment after disease onset increases the chance of a favorable response.