THE EFFECT OF ADRENAL DENERVATION ON ACTH-INDUCED HYPERTENSION IN SHEEP

SUMMARY 1. The effect of surgical denervation of the adrenal gland on ACTH-induced hypertension in the sheep has been examined. ACTH (80 iu/day) was administered for 5 days to eight sheep before and after bilateral surgical denervation of the adrenal.
2. In intact sheep, ACTH-induced hypertension is associated with a significant increase in cardiac output and heart rate. Adrenal denervation obtained by sectioning of the lumbar sympathetic and splanchnic nerves supplying the adrenal gland did not alter the magnitude or time course of the hypertension, or the increase in heart rate.
3. Adrenal denervation did not affect the increase in plasma sodium, the fall in plasma potassium, the initial urinary sodium retention, the increase in water turnover or the changes in blood corticosteroids which are seen during ACTH administration to intact sheep. However, in these adrenally denervated sheep ACTH treatment did not significantly change cardiac output.
4. This study suggests an important role for a factor or factors from the adrenal cortex in causing ACTH-induced hypertension.     

Macrophage Dependence of Galactose Oxidase Induced Transformation of Human Lymphocytes

The role of macrophages in the transformation of human lymphocytes by the mitogen galactose oxidase was studied. Monocyte depleted, purified T or B cells did not undergo blastogenesis after treatment with galactose oxidase. When galactose oxidase-treated purified T cells were cultured with macrophages, a slight proliferative response was obtained. B cells treated similarly showed no response. When macrophages were treated with galactose oxidase, and then T B, T, or B cells were added, proliferative responses were observed in all 3 categories. Finally, supernatants of media in which galactose oxidase-treated macrophages were cultured also demonstrated the property of stimulating lymphocyte transformation. These results are consistent with current concepts of mitogen 'presentation“ and the elaboration of soluble factors by macrophages in mediating the activation of lymphocytes in response to stimulating agents.     

Staging in tubular oxygenators — Experimental results

The oxygenation rate of blood flowing through permeable tubes can be increased by mixing or turbulence of the blood. Staging of the tubes has been suggested as one means of enhancing the oxygenation rate. A series of experiments has been performed to investigate the feasibility of staging and the results show a definite advantage in oxygen transfer compared with regular straight tubes.     

Evaluation of Two Standardized Disk Methods for Testing Antimicrobial Susceptibility of Pseudomonas aeruginosa and of the Enterobacteriaceae

Two standardized disk diffusion susceptibility testing methods were compared using Pseudomonas aeruginosa and members of the Enterobacteriaceae. The standard Bauer-Kirby method and the agar overlay method of Barry et al. were compared using carbenicillin (50- and 100-mug disks), gentamicin, polymyxin B, and colistin sulfate. Both methods gave nearly comparable zone sizes with the enteric bacilli. However, with P. aeruginosa the agar overlay method gave zones 1 to 2 mm smaller than the Bauer-Kirby method with all drugs except gentamicin. In spite of these small differences, further examination of minimal inhibitory concentration-zone size correlations indicated that the same interpretive zone standards can be applied to either diffusion technique. For testing carbenicillin against Pseudomonas sp., 50-mug disks were unsatisfactory, especially with the agar overlay method; 100-mug disks were far superior with both methods.     

Digitalis use in acute myocardial infarction: current concepts

Digitalis is one of the oldest and most commonly prescribed medications. There has been continuing controversy regarding its use in acute myocardial infarction. Recent information from animal experiments and clinical investigation serves as a guide for its appropriate use in this situation. When it is used appropriately and judiciously there is no increase in toxicity or cardiac arrhythmias. In fact, there is benefit to the patient who has a failing myocardium associated with acute myocardial infarction.