The response of the skin of swine to increasing single exposures of 250-KVP X-rays

When the skin of the shoulder ("A" field) and lower back ("C" field) is irradiated through 10-cm-diameter fields with 250-kVp x-rays, having a HVL of 0.87 mm copper, a dose range is reached between approximately 1600 rads and 3000 rads in which a moist reaction is or is not formed. If a moist reaction is formed, it either heals completely, partially, or not at all. The evolution, time course, and dose dependence of the moist reaction that occurs following irradiation has been determined. The moist reaction is found at 17.5 +/- 0.6 days in the "A" field, and 20.8 +/-0.8 days in the "C" field. The reaction evolves to involve from 5 % to 100% of the field by 24.9 +/- 0.5 days in the "A" field and by 28.5 +/- 1.0 days in the "C" field. Healing is complete by 36.0 +/-1.0 days in the "A" field and by 38.0 +/- 1.3 days in the "C" field. The area of the field involved with a moist reaction at the time of maximal involvement is dose-dependent. The area of the field involved with a moist reaction at the time of complete healing is also dose-dependent. The dose at which 50 % of the fields were not healed was 2273 +/-103 rads in the "A" field, 2578 +/-141 rads in the "C" fields, and 2437 +/- 89 rads in the "A" and "C" fields. The values in the "C" field are significantly different from those in the "A" field except for the dose at which 50 % of the fields were not healed and the time at which the field was maximally healed.     

Infection in Mouse Peritoneal Cavity with a Pyrimidine-requiring Mutant and Naturally Occurring Staphylococcus aureus Strains

The lethal activity of a thymineless mutant of Staphylococcus aureus Wood 46 strain has been compared with that of three naturally occurring strains: parent Wood 46, Smith, and coagulase-negative SA-13. The thymineless mutant and the parent Wood 46 strain showed a sharp decline in culturable units from the peritoneal cavity in the first 4 hr after their injection. After 6 hr, that is, 2 hr before the mice began to die, the number of culturable units of the thymineless mutant was still declining, whereas that of the parent strain increased; for both strains, the number of units was still lower than that of the inoculum. Although the thymineless mutant, unlike the parent strain, was apparently unable to multiply in mouse peritoneal cavity, it killed mice at a similar rate. The highly virulent Smith strain known to multiply rapidly and the avirulent coagulase-negative SA-13 strain were used as additional controls. Under our experimental conditions, death of mice after the injection of the thymineless mutant in the peritoneal cavity did not seem to be due to bacterial multiplication but to toxicity, death being delayed by antitoxin. The pyrimidine-requiring auxotroph we used could be better material than killed bacteria to study some aspects of the lethal activity of S. aureus.     

Short- and Long-Term Alterations of Gene Expression in Limbic Structures by Repeated Electroconvulsive-Induced Seizures

Rats were submitted to a series of 10 daily electroconvulsive shocks (ECS). A first group of animals was killed 1 day after the last seizure and a second group 30 days later. Tyrosine hydroxylase (TH) activity was measured using an in vitro assay in the nucleus caudatus, anterior cortex, amygdala, substantia nigra, ventral tegmental area, and locus ceruleus. The mRNA corresponding to this enzyme (TH-mRNA) was evaluated using a cDNA probe at the cellular level in the ventral tegmental area, substantia nigra, and locus ceruleus. Met-enkephalin (MET)-immunoreactivity and the mRNA coding for the preproenkephalin (PPE-mRNA) were assayed in striatum and the central nucleus of the amygdala. The day after the last ECS an increase of TH activity was observed in the ventral tegmental area, locus ceruleus, and substantia nigra in parallel with a similar increase in the amygdala and striatum; in the anterior cortex TH activity remained unchanged. TH-mRNA was increased in the locus ceruleus, evidencing the presence in this structure of a genomic activation. The amounts of MET and PPE-mRNA were unaffected in the striatum but increased in the amygdala. Thirty days after the last ECS we observed a decrease of TH activity in the amygdala and of TH-mRNA amount in the ventral tegmental area. In the locus ceruleus TH-mRNA remained higher in treated animals than in controls whereas TH activity returned to control levels. These results demonstrate that a series of ECS induces an initial increase of the activity of mesoamygdaloid catecholaminergic neurons followed by a sustained decrease through alterations of TH gene expression which could mediate the clinical effect of the treatment.