Induction of muscle-relaxing factor by staphylococcal alpha-toxin.

Brain tissue and serum from mice intracerebrally injected with 1 microgram of staphylococcal alpha-toxin contained elevated amounts of a naturally occurring brain tissue component(s) called muscle-relaxing factor (MRF). MRF induced reversible, generalized, flaccid paralysis of mice after intracerebral but not intraperitoneal or intravenous administration. MRF (i) was soluble in Hanks balanced salt solution and in acidified (pH 2) Hanks balanced salt solution, in which it partitions into ethyl acetate, acetone, and methanol; (ii) was separated from some pigments by thin-layer chromatography on silica gel plates; (iii) did not comigrate with prostaglandin and leukotriene standards during high-pressure liquid chromatography with a mu Bondapak fatty acid column; and (iv) did not contain amino acids, exhibit absorption maxima at a wavelength range of 210 to 600 nm, or fluoresce when exposed to UV light. MRF has been detected in rabbit brain that has been stored frozen at -70 degrees C and has been enhanced in vitro in slices of both mouse and rabbit brain following incubation of the brain slices with staphylococcal alpha-toxin. Studies to identify the chemical nature of MRF and the mechanism by which, in mice, it induces reversible, flaccid paralysis of voluntary muscle are continuing.     

Injury of myelin sheaths in isolated rabbit vagus nerves by alpha-toxin of Staphylococcus aureus.

S. Szmigielski, M. Blankenship, J. P. Robinson and S. Harshman. Injury of myelin sheaths in isolated rabbit vagus nerves by α-toxin of Staphylococcus aureus. Toxicon17, 363–371, 1979.—Dissected rabbit vagus nerves were incubated in vitro with 0·24-4 μg of purified staphylococcal α-toxin (17,000 H.U./mg protein) per ml. The release of ⁸⁶Rb from prelabeled nerves and the electrical activity of nerves (action potential) were measured and correlated with morphological changes observed by electron microscopy. At a concentration of α-toxin of 2 μg/ml, 30% of incorporated ⁸⁶Rb was released from the nerves after 30 min of incubation. The electrical activity was maintained over this time period and required an additional 30 min before failing completely. Concentrations of α-toxin below 2 μg/ml had no effect on either the release of ⁸⁶Rb or the electrical activity even after 60 min of incubation of the nerves. In contrast, dramatic changes in the morphology of the myelin sheaths are readily demonstrated after 30 min of incubation and can easily be observed at 0·2 μg/ml, a level of α-toxin which has no effect on ⁸⁶Rb release or electrical activity. Both non-myelinated nerve fibers and Schwann cell membranes appear to be more resistant to the action of α-toxin. We conclude that, of the parameters measured, disorganization of myelin sheaths is the first recognizable symptom of injury to peripheral nerves by staphylococcal α-toxin.     

草珊瑚中的一个新倍半萜内酯

草珊瑚为金粟兰科植物Sarcandra glabra(Thumb.)Nakai的全株,又名接骨金粟兰、肿节风、九节风、九节茶、接骨木等。有清热祛风,散瘀接骨之功效,民间用于治疗肺炎、凤湿性关节炎等。近年来做成制剂治疗溃疡病、癌症等。已报导的化学成分有延胡索酸、琥珀酸及异白蜡树定(isofraxidin)等。今从草珊瑚叶中分得一个新的倍半萜内酯,本文鉴定其结构为(—)-istanbulin A。