Comparison of the effects of neonatal thymectomy on Plasmodium berghei,Trypanosoma lewisi and Trypanosoma cruzi infection in the albino rat

Summary Neonatally thymectomized COBS albino rats (Charles River) were infected with the pathogenic intraerythrocytic protozoan parasite Plasmodium berghei, or the nonpathogenic extracellular protozoan Trypanosoma lewisi or a pathogenic protozoan having both intra- and extracellular forms, Trypanosoma cruzi. Neonatally thymectomized, sham-operated, and unoperated control rats were challenged with 1.0×10⁶ P. berghei infected erythrocytes at 6, 8 or 12 weeks of age and parasitemia, anemia and mortality were studied. Others were infected with 1.0×10⁶ T. lewisi at 8 weeks of age or 2.0×10⁵ trypomastigotes of T. cruzi at 5–6 weeks of age and parasitemia was investigated. Each age group of neonatally thymectomized rats infected with P. berghei developed significantly higher parasitemias, more severe anemias, and in younger rats, higher mortalities than sham-operated or unoperated controls. Significant differences were observed in the mean parasitemia of neonatally thymectomized and sham-operated or unoperated control rats challenged with T. cruzi. Significant differences were not observed in neonatally thymectomized and sham-operated or unoperated controls challenged with T. lewisi. These observations suggest that in the rat, thymus dependent immune reactions may play a role in acquired immunity to the intracellular blood parasite, P. berghei and to T. cruzi which has an intra- and extracellular stage, but probably does not have a significant role in acquired immunity to the extracellular blood protozoan parasite, T. lewisi.     

Comparison of the Minitek test system with a conventional screening procedure for identification of Enterobacteriaceae.

A Minitek basic 9 disc/11 test system plus arabinose, inositol and rhamnose was compared with a conventional six tube screening system for identification of members of the family Enterobacteriaceae. Correlation varied from 88.3 to 100% with the various substrates when studied against 737 strains of these and other gram-negative bacteria recently isolated in our clinical laboratory. Two discs, citrate and ornithine, which originally gave a correlation of 88.3 and 95.5% respectively were modified so that a final correlation of 99.4 and 96.3% was obtained. The average correlation using the eleven discs was 97%.     

Abnormal auditory evoked potentials in hereditary motor-sensory neuropathy.

From a kinship with a dominantly inherited motor-sensory neuropathy, we studied 2 brothers with brainstem auditory evoked potentials and behavioral audiometric tests. They had abnormal prolongation of I-III interpeak intervals. Wave V was poorly developed. Conventional audiometric tests did not reveal a peripheral hearing loss. It is probable that their auditory nerves and spiral ganglia are undergoing a pathophysiological process analogous to that of their peripheral nerves.     

Insurance plan raises benefits, lowers costs.

The Direct Service Contract encourages hospital employees to use their own hospital for medical services. The plan benefits the hospital, cuts costs, and raises employee morale.