In vivo effects of acute changes in osmolality and sodium concentration on myocardial contractility.

Effects of acute changes in osmolality and sodium concentration (Na) on myocardial contractility (MC) were examined in anesthetized dogs. Using a carotid to left anterior descending bypass, 4 cc of NaCl and/or dextrose of varying osmolality as injected and the percentage of change in MC measured. At Na = O mEq/L, a positive inotropic response occurred, which varied inversely as osmolality increased from 300 (MC = 100 +/- 23%) to 700 mOsm/L (MC = 39 +/- 10%, p less than 0.

Ventricular fibrillation during coronary angiography: an analysis of mechanisms.

To investigate the mechanisms of ventricular fibrillation (VF) during coronary angiography, we assessed ventricular automaticity, local QT intervals, local conduction characteristics, and the ability to induce arrhythmias with premature ventricular stimulation in 30 dogs after intracoronary injections of 4 to 6 cc of Renografin 76 (RG 76). Ventricular automaticity was measured in six dogs as the idioventricular escape rate following intense vagal stimulation and was unchanged (51 +/- 6 vs 52 +/- 6 bpm, p greater than 0.05) with 6 cc of RG 76.

Ventricular fibrillation during coronary angiography: reduced incidence in man with contrast media lacking calcium binding additives.

The intracoronary injection of contrast media during coronary angiography occasionally results in ventricular fibrillation. Experimental studies have implicated the calcium sequestering agents, sodium citrate and EDTA in Renografin 76 (RG76), as contributing to this complication. Angiovist 370 (AV370) is a contrast medium similar to RG76 except that it contains disodium calcium EDTA instead of EDTA and sodium citrate.

Application of recombinant DNA technologies to studies on chicken growth hormone.

Messenger RNA isolated from chicken pituitaries was used to construct a chicken pituitary cDNA library. A chicken growth hormone cDNA clone was isolated using 32P-labeled mammalian growth hormone cDNA probes. The amino acid sequence (derived from the DNA sequence) of the mature form of chicken growth hormone shows 77% homology with that of bovine growth hormone.

Ventricular fibrillation during coronary angiography in dogs: the role of calcium-binding additives.

Coronary angiography with Renografin 76 (RG76) occasionally results in ventricular fibrillation (VF). Angiovist 370 (AV370) is a contrast medium similar to RG76 except the calcium-sequestering agents, sodium citrate and EDTA in RG76 have been replaced by calcium EDTA. To determine whether these sequestering agents contribute to contrast medium-induced VF, a comparison was made of the effects of intracoronary injections of RG76, AV370, and saline solutions containing sodium citrate and EDTA (CIT/EDTA) and calcium EDTA (CA EDTA) on myocardial conduction, local QT intervals, and incidence of spontaneous and induced VF in 32 dogs.

Inotropic effects of ionic contrast media: the role of calcium binding additives.

Renografin-76 (RG76) regularly depresses myocardial contractility during coronary angiography. Angiovist-370 (AV370) is a contrast medium similar to RG76 except the calcium sequestering agents sodium citrate and EDTA in RG76 have been replaced by calcium EDTA (an additive that does not bind additional calcium). To determine if the calcium sequestering agents contribute to the mechanical depression produced by ionic contrast media, this study compared the inotropic response of RG76 to that of AV370.

Effects of treatment with thiamin antagonists, oxythiamin and pyrithiamin and of thiamin excess of the levels and distribution of thiamin in rat tissues.

Levels of thiamin and its derivatives in brain, heart and liver were determined in control, thiamin-deficient, pyrithiamin-treated and oxythiamin-treated rats at various times after the start of treatment. With 10 micrograms of thiamin/100 g/day subcutaneously, rats rapidly lost thiamin from the tissues until growth maintenance levels were reached. Oxythiamin had a minimal further effect on tissue thiamin while pyrithiamin caused further marked reduction.

Supraventricular pacemaker underdrive in the absence of sinus nodal influences in the conscious dog.

The ability to reduce and maintain heart rate by electrical stimulation (underdrive) was tested in three groups of chronically instrumented dogs: sinoatrial node intact, ectopic atrial pacemaker produced by injection of rapidly hardening latex into the sinoatrial nodal artery, and idioventricular pacemaker produced by injection of formalin into the atrioventricular node. In the conscious unsedated state, underdrive of sinoatrial or idioventricular pacemakers resulted in competition between driven and intrinsic foci. However, the cycle length of ectopic atrial pacemakers could be increased by 148.

Effect of Temperature on Survival of Yeast in 45° and 65° Brix Orange Concentrate.

A study was conducted to determine the effect of cold-temperature storage on yeast survival in 45° and 65° Brix orange concentrate under simulated conditions of bulk storage. Suspensions were prepared from each of three strains of yeast which had been identified as to genus and species. Orange concentrates at 45° and 65° Brix were inoculated to contain approximately 1,000,000 organisms per ml.

A Simple Method to Screen Fruit Juices and Concentrates for Heat-Resistant Mold.

A simple test is described for screening fruit juices, juice concentrates, or any suspected juice products for the presence of heat resistant mold. Product in bottles heated at 77 C is plated. The plates and contents remaining in the bottles are incubated for periods up to 30 days at 30 C.