Staphylocidal action of thrombin-induced platelet microbicidal protein is not solely dependent on transmembrane potential.

Thrombin-induced platelet microbicidal protein (tPMP) is a small, cationic, antimicrobial peptide released from rabbit platelets when stimulated with thrombin. We studied the relationship between staphylococcal transmembrane potential (delta psi) and tPMP staphylocidal activity. A genetically related pair of Staphylococcus aureus strains, 6850 and JB1, which differ in delta psi generation (-143 and -97 mV, respectively) were used. Mutant JB-1 was substantially less susceptible to tPMP than the parental strain, 6850. Menadione supplementation, which normalized the delta psi of strain JB-1, did not restore JB-1 tPMP susceptibility. These findings suggest that the staphylocidal activities of tPMP require factors other than or in addition to an intact delta psi.     

A simple method for short-term (6-hour) transport of the dog heart prior to orthotopic transplantation

A method of transporting the isolated dog heart for periods of up to 6 hours is described. It consists essentially of flush-cooling the heart with a suitable water-based solution at 4-6° C. followed by storage in a specially designed portable container which maintains the temperature of the heart at 4-6° C. The viability of the hearts was tested by orthotopic transplantation. Of nine hearts so stored (six for 6 hours), all supported the recipient circulation immediately after transplantation, with a mean systemic arterial pressure of 70 to 100 mm. Hg and a mean max. dp/dt of the left ventricular pressure of 1,050 mm. Hg/second without catecholamine stimulation. A comparable group of hearts flush-cooled in the same way but stored in ice after the manner of the method used for kidney transport was markedly inferior in performance to those stored at 4-6° C. Some of the limitations of non-perfusion methods of storing the heart are discussed.     

Apomorphine-induced aggression: an evaluation of possible sensitizing factors in the rat.

The effects of prior experience with fighting and prior experience with both apomorphine and fighting were evaluated as possible sensitizing factors in rat intraspecific aggression induced by apomorphine. Results revealed that prior experience with the drug alone, or with fighting alone, had no effect on apomorphine-induced aggression. However, animals that had previously fought under the influence of apomorphine showed even higher levels of aggression suggesting that repeated experience with both the drug and fighting induces a type of sensitization.     

Phenobarbitone-induced enlargement of the liver in the rat: its relationship to carbon tetrachloride-induced cirrhosis.

The yield of severe cirrhosis of the liver (defined as a shrunken finely nodular liver with micronodular histology, ascites greater than 30 ml, plasma albumin less than 2.2 g/dl, splenomegaly 2-3 times normal, and testicular atrophy approximately half normal weight) after 12 doses of carbon tetrachloride given intragastrically in the phenobarbitone-primed rat was increased from 25% to 56% by giving the initial "calibrating" dose of carbon tetrachloride at the peak of the phenobarbitone-induced enlargement of the liver. At this point it was assumed that the cytochrome P450/CCl4 toxic state was both maximal and stable. The optimal rat size to begin phenobarbitone was determined as 100 g, and this size as a group had a mean maximum relative liver weight increase 47% greater than normal rats of the same body weight. The optimal time for the initial dose of carbon tetrachloride was after 14 days on phenobarbitone.