A chemically defined medium using commercially available alpha-MEM supplemented with hemin, HEPES, L-glutamine, D-glucose, folic acid, D-biotin and adenine supports the luxuriant growth and propagation of Leishmania donovani promastigotes. A peak parasite population of about 7.0 x 10(7)/ml at stationary phase and a population doubling time of 11.4 h for high-subpassage promastigotes were obtained. The medium was suitable for transformation of isolated amastigotes from infected hamster spleen. Promastigotes could be detected by culturing kala-azar patients' bone-marrow aspirate or spleen puncture material in this medium. Four out of six freshly transformed isolates gradually adapted and grew well in this medium. Macroscopic colonies appeared on agar plates prepared with the medium within 16-20 days after inoculation. The cloning efficiency was increased about five-fold by glycerol supplementation.

Animals↗

PubMedDate not supplied

Effect of alpha-adrenergic receptor blockers on the vulnerability of cat heart to ventricular fibrillation.

Recently, alpha-adrenergic receptors have been implicated in the precipitation of arrhythmias associated with myocardial ischemia and reperfusion. The present investigation has been undertaken to study the effect of alpha-adrenoceptor antagonists on electrically induced ventricular fibrillation. The effect of ventricular fibrillation on the alpha-adrenergic receptor population in myocardium and its modification by phentolamine pretreatment has also been investigated. Phentolamine and prazosin raised the ventricular fibrillation threshold significantly. However, yohimbine was protective at high doses only (3 and 5 mg/kg). There was no change in alpha-receptor population and affinity after ventricular fibrillation. Cyclic AMP levels increased in the fibrillating myocardium. Pretreatment with phentolamine did not prevent the decrease in blood flow observed after electrically induced ventricular fibrillation. It is concluded that alpha 1-adrenergic receptor blockade is protective against ventricular fibrillation in cats.

Adrenergic beta-Antagonists↗