In vitro production of Clostridium perfringens enterotoxin and its detection by reversed passive hemagglutination

The reversed passive hemagglutination (RPHA) test yielded a positive reaction in 2 h with as little as 0.5 ng of purified Clostridium perfringens enterotoxin (CPE) per ml as well as with cultures of some C. perfringens grown in Duncan-Strong (DS) medium. This method is the most sensitive, the simplest, and the fastest among all reported. The time course of CPE production of Clostridium perfringens NCTC 8798 in DS was investigated by RPHA. CPE in culture was detectable at 4 h, increased gradually, reached a maximum at 12 to 14 h, and remained at a high level of 20 mug/ml through 48 h of incubation. CPE synthesized within cells is released easily by sonic disruption of young cultures and by aging the cultures 20 h or more. Heat shock of the cell inoculum was essential for CPE production by C. perfringens in DS.

Effects of labyrinthectomy on optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN)

OKN and OKAN were affected by unilateral and bilateral labyrinthectomy. The maximum velocity of slow phases of OKN induced by drum rotations above 60-75 degrees/sec in either direction was lower after unilateral and bilateral labyrinthectomy. The frequency of OKN was also decreased, and the total deviation of the eyes was reduced for OKN induced by these drum speeds. Changes in OKN eventually recovered. OKAN was reduced in duration after unilateral labyrinthectomy, being initially shorter to the ipsilateral than to the contralateral side. OKAN could no longer be evoked after bilateral labyrinthectomy. This loss was permanent. These data demonstrate the importance of the vestibular system in maintenance of OKN and OKAN.