Alteration of human erythrocyte plasma membranes by perfringolysin O as revealed by freeze-fracture electron microscopy. Studies on Clostridium perfringens exotoxins V

When human erythrocyte membranes were treated with perfringolysin O (Clostridium perfringens theta-toxin) and examined by electron microscopy after freeze-fracture, two ultrastructural alterations were observed in fracture faces of membrane. (1) A random aggregation of intramembranous particles was seen in the fracture face of the protoplasmic half (PF face) of all membranes treated with the toxin, even if at a low concentration (40 hemolytic units/ml). On the other hand, the aggregation in the fracture face of the exoplasmic half (EF face) was observed only in membranes treated with a high concentration (3300 hemolytic units/ml) for 2 h. (2) Round protrusions and "cavities" with 30 nm in diameter were visible in EF and PF faces of membranes treated with a high concentration, respectively. These structures were always protruded toward cytoplasmic side, but did not appear to form holes through the membrane. Ring and arc shaped structures with a dark center of 26 nm and a distinct border of 5 nm in width were observed when the toxin alone was negatively stained at a very high concentration (170,000 hemolytic units/ml). These structures were also produced in the presence of cholesterol even if the toxin concentration was low.

Clostridium perfringens exotoxins. VI. Reactivity of perfringolysin O with thiol and disulfide compounds

The reactivity of perfringolysin O with thiol and disulfide compounds was studied. The activation potency of thiols was roughly proportional to the reaction rate constants of 5,5'-dithiobis-(2-nitrobenzoic acid) with thiols, which should be inversely proportional to their oxidation-reduction potentials. 1,2-Dimercaptoethane, which had the highest rate constant, most potently activated the toxin among the thiols tested and 4,4'-dipyridyl disulfide, which is known to be one of the most potent thiol-disulfide exchanging reagents, strongly inhibited toxin activity. Toxin activity was also inhibited by other thiol inhibitors.

A prospective study of epilepsy following neonatal convulsions

In a prospective study of 130 infants with neonatal convulsions, the frequency and type of epilepsy and the relationship between the presumptive etiology of neonatal convulsions and subsequent epilepsy were investigated in 82 survivors exclouding those dying and lost to follow-up. Of these 82 children, 15 (18.2%) were found to have epilepsy, which was of generalized type in seven (8.5%), infantile spasm in four (4.9%), focal seizures in three (3.6%) and myoclonic seizures in one (1.2%). Febrile convulf neonatal convulsions were asphyxia, intracranial hemorrhage or neonatal meningitides in most instances, but no particular relationship was noted between the presumptive etiology of neonatal convulsions and the type of subsequent epilepsy. In 11 (73.3%) of the 15 epileptic children, convurrent mental retardation, cerebral palsy and postmeningitic hydrocephalus were noted. Evidence from RI cisternography, pneumoencephalography and cerebral angiography indicated that perinatal or neonatal brain damage responsible for epilepsy might be organic in nature. The fact that epilepsy occurred later in many of cases of neonatal convulsions of unidentified etiology suggests that brain damage incurred during fetal life might also be implicated at least in some instances. The onset of epilepsy in this series was relatively early, invariably before three years of age.