BOTULINUM TOXIN, TYPE A: EFFECTS ON CENTRAL NERVOUS SYSTEM

This study has demonstrated that type A botulinum toxin has a depressant effect on the cortical electrical activity of anesthetized and unanesthetized monkeys. Simultaneous recordings of vital signs indicated a relative lack of change in the electrocardiogram, respiration, blood pressure, and heart rate during this time. The change in the electroencephalogram appeared cyclic in nature and independent of dose or time. All animals exhibited signs of respiratory failure characterized by a gradual interference with neuromuscular transmission at the diaphragm, and subsequently died an anoxic death.

TEMPERATURE REGULATION BY HYPOTHALAMIC PROPORTIONAL CONTROL WITH AN ADJUSTABLE SET POINT

The role of the hypothalamic and skin temperatures in controlling the thermal response of a resting animal was studied by measurements of 1) hypothalamic, rectal, ear skin, and trunk skin temperatures on the resting dog and rhesus monkey in hot, neutral, and cold environments; and 2) the thermal and metabolic responses of a dog in neutral and cold environments during and immediately after holding the hypothalamus at approximately 39.0 C by means of six thermodes surrounding the hypothalamus and perfused with water. The results indicate that 1) a resting animal shivers in a cold environment with the same or higher hypothalamic temperature as the same animal in a neutral environment; 2) a resting animal pants in a hot environment with the same or lower hypothalamic temperature as the same animal in a neutral environment; 3) the hypothalamus is nonetheless strongly responsive to an increase or decrease of 1 C; 4) the rate of heat loss increases at the onset of sleep while the hypothalamic temperature is falling; 5) the hypothalamic temperature is 1–2 C lower during sleep even though thermoregulatory responses are the same as when awake; 6) the rate of heat loss decreases upon awakening while the hypothalamic temperature is rising. The discussion of these results includes a suggestion that the set point for temperature regulation is 1) decreased by a rising or elevated skin and extrahypothalamic core temperature, 2) increased by a falling or lowered skin and extrahypothalamic core temperature, 3) decreased upon entering and during sleep and is increased upon awakening.

hypothalamic temperature; temperature set point; hypothalamic stimulation; dog temperature regulation; monkey temperature regulation

Submitted on October 15, 1962

PURIFICATION OF TYPE B STAPHYLOCOCCAL ENTEROTOXIN

Frea, James I. (University of Wisconsin, Madison), Elizabeth McCoy, and F. M. Strong. Purification of type B staphylococcal enterotoxin. J. Bacteriol. 86:1308-1313. 1963.-A procedure for the production and isolation of type B staphylococcal enterotoxin in yields up to 4 mg per liter of toxic culture is presented. Staphylococcus aureus S6 was grown in shake flask cultures at 37 C for 24 hr in a medium consisting of 2% Hy-Case S.F., 0.3% yeast extract, calcium pantothenate, nicotinic acid, and thiamine. Cells were removed by centrifugation and the supernatant fluid was concentrated by dialysis against polyethylene glycol. Enterotoxin was isolated from the concentrate by ethanol precipitation, gel filtration on a G-100 Sephadex column, and Sephadex-column electrophoresis. The purified toxin was identical to type B reference enterotoxin on both disc electrophoresis and Ouchterlony gel diffusion. It contained no carbohydrates, lipids, or nucleic acids, gave positive tests for protein; and contained 11.6% N. The preparation showed no coagulase, alpha-hemolysin, or deoxyribonuclease activity. Emesis in monkeys resulted when the experimental toxin was injected at the rate of 0.26 mug of N per kg of body weight.

IMMUNOLOGICAL AND BIOCHEMICAL STUDIES ON SERUM HAPTOGLOBIN

Antibody to purified type 1-1 human serum haptoglobin was obtained in rabbits. Using this antiserum it was demonstrated that the antigenic determinants of the haptoglobin molecule reside in both α- and β-chains. No immunological difference between the normal α^1F- and α^1S-chains of haptoglobin could be detected. A number of healthy individuals whose haptoglobin pattern appeared normal by starch gel electrophoresis were shown to possess a haptoglobin which could be distinguished immunologically from the common haptoglobin types. These immunological atypical haptoglobins have been observed in individuals of types 1-1, 2-1, and 2-2. Combined immunological and chemical studies of purified haptoglobin have enabled the construction of a tentative model for the structure of human type 1-1 haptoglobin.

CARDIOVASCULAR CONCOMITANTS OF THE CONDITIONED EMOTIONAL RESPONSE IN THE MONKEY

Flow transducers were surgically implanted on the terminal aorta of five monkeys. A classical conditioning procedure, in which a light preceded a brief shock, was superimposed upon a variable-interval schedule of food reinforcement for key pressing (three monkeys) and alternated with an avoidanceschedule of shock reinforcement for key pressing (two monkeys). Suppression of the rate of the response of key pressing and sizable increase in blood flow and heart rate during the light were obtained for all animals.

EFFECT OF ILLUMINATION AND D-AMPHETAMINE ON THE ACTIVITY OF THE RHESUS MACAQUE

The activity of the Rhesus macaque was measured under three levels of ambient illumination and three dosages of d-amphetamine. Analysis of variance indicated that activity increases as a function of increasing level of illumination and decreases as a function of increasing dosages of amphetamine. The interaction effect was nonsignificant.

SUSCEPTIBILITY OF THE LLC-MK2 LINE OF MONKEY KIDNEY CELLS TO HUMAN ENTEROVIRUSES

The relative susceptibility of the LLC-MK2 cell line and primary rhesus monkey kidney cultures to thirty-eight prototype strains of human enteroviruses is described; of these strains only ECHO types 16, 18, 21 and 23 failed to cause CPE in the continuous cell line. The efficiency of the two tissues for the isolation of enteroviruses from faecal extracts is compared. The results show that the LLC-MK2 cell line is very satisfactory for the isolation of Coxsackie B and polioviruses, but not so useful for the isolation of ECHO viruses. The identification of enteroviruses by neutralization tests in LLC-MK2 cells is successful.