Protection of PC12 cells glutathione peroxidase in L-DOPA induced cytotoxicity

L-DOPA may cause side-effects during the treatment of Parkinson's disease. We investigated the role of glutathione peroxidase (GSHPx) in cellular defense against L-DOPA cytotoxicity. A line of PC12 cells overexpressing GSHPx with plasmid pRc/CMV-GSHPx was established and stable transfectants overexpressing GSHPx were used for this study. GSHPx activity was found to be 1.5-fold higher in GSHPx-transfectants than in mock-controlled transfectants. Transfectants over expressing GSHPx were also significantly more resistant to exposure to either L-DOPA or t-butyl hydroperoxide than mock-transfected cells. Results suggested that L-DOPA may cause neuronal cell death by an oxidative pathway and GSHPx may play an important role in cellular defense against oxidative stress.     

MILK COAGULATION CUT-TIME DETERMINATION USING ULTRASONICS

A nondestructive method of determining milk coagulation cut-time was investigated. Velocity and attenuation of ultrasonic waves through coagulating skim milk were measured after rennet addition. the ultrasonic attenuation measurements were found suitable for distinguishing the effect of different experimental variables (three levels of temperature, rennet and CaCl₂). Based on the rate of change of attenuation during coagulation, a turning point was defined at which the attenuation rate change was -0.1 neper/m/min. the cut-time was proposed to be 20 min from the time the turning point was observed. the cut-times predicted by this criterion were statistically similar to those predicted by the manual method currently used in the industry.