Effects of interferon inducers on chemically-induced mutagenesis and carcinogenesis

The in vitro study on an isolated system of myocardial contractile proteins determined optimal concentrations of the positive inotropic action and biological activity ranges of beta-methyldigoxin (beta-MD), strophanthin K, K-strophantozide, beta-acetyldigoxin (beta-AD), milrinone, and amrinone. Optimal concentrations of the beta-MD and strophanthin K (10(-2) and 10(-6) M, respectively) significantly increased qualitatively and quantitatively the economy and thermodynamic efficiency, altered the energy transformation in the contractile protein system under the isometric contraction, whereas the beta-AD produced only the quantitative effect. However, the beta-MD and strophanthin K at concentrations exceeding the optimal one by one order lost the ability to produce the qualitative effect, retaining only the quantitative one in the actomyosin ensemble. The strophanthin K significantly increased the economy of a single actomyosin ensemble in the force generation phase and the beta-MD in the tension maintenance phase. Unlike the strophanthin K, the beta-MD did not slow down (did not worsen) the relaxation process. This provides grounds to conclude that the beta-MD produces most favorable effect on the energy transformation by myocardial contractile proteins.     

Inhibitory effect of crocetin on intracellular nucleic acid and protein synthesis in malignant cells

The possibility that dietary intake of diverse naturally occurring compounds may influence the occurrence of cancer is receiving considerable scientific attention. Previously, it was reported that an extract (Crocus sativus), which contains carotenoids, had an antitumor effect and inhibited colony formation and nucleic acid synthesis by malignant human cells. Epidemiological and experimental research has indicated that carotenoids might act as antitumor agents. We have studied crocetin, a carotenoid isolated from saffron, which has been shown to have biological activity. In our experiments we utilized three malignant human cell lines: HeLa (cervical epitheloid carcinoma), A549 (lung adenocarcinoma) and VA13 (SV-40 transformed fetal lung fibroblast) cells. The effect of crocetin on colony formation and cellular DNA, RNA and protein synthesis in these cells has been examined. Incubation of these cells with crocetin for 3 h caused a dose-dependent inhibition of nucleic acid and protein synthesis. Crocetin also had a dose-dependent inhibitory effect on DNA and RNA synthesis in isolated nuclei and suppressed the activity of purified RNA polymerase II.     

Spectral analysis of electrocardiogram signals of the isolated guinea pig heart for the detection of arrhythmias

Fast Fourier Transform analysis of the electrocardiogram (ECG) signal of the isolated guinea pig heart has been used to investigate the subtle ECG changes that precede cardiac arrhythmias. During prolonged periods of regular contractile activity, spectral analysis of the isolated guinea pig heart ECG revealed that the major frequency components were evenly distributed over the range 0-64 Hz. Prior to arrhythmias or during ischaemia however, there was a major reduction in the amplitude of the higher frequency components. Thus, Fast Fourier Transform analysis of an ECG record enables the detection of the subtle ECG configuration changes that precede cardiac rhythm disturbances. The potential application of this technique for the prediction of cardiac arrhythmias is discussed.     

The nature and use of purified insulins

The limited availability of highly purified insulin preparations for the treatment of diabetes mellitus in australia since 1975, has prompted a review of their history, clinical use and potential in the treatment of diabetics receiving insulin.     

Effects of physical training on ventilatory equivalent and respiratory exchange ratio during weight supported, steady-state exercise

Thirty-three college men participated in a 9-week endurance training program. An equal number of subjects served as controls. Pre- and post-test metabolic measurements were made during 10 min of submaximal exercise (1080 kpm/min at 60 rpm) and 15 min of recovery. Measurements included oxygen consumption, CO2 production, ventilatory equivalent (Ve/VO2 ratio) and respiratory exchange ratio (R). A three factor design variance analysis was used to analyze the effects of training on min-by-min exercise and recovery Ve/VO2 ratio and R. For the experimental group training resulted in a significant improvement in ventilatory efficiency during exercise, as well as a significant decrease in R. During recovery, Ve/VO2 and R decreased significantly for both groups although the magnitude of change was greater for the group that trained. Apparently, there was a significant habituation effect due to test procedures for the control group. The results are discussed in terms of lactate production and substrate utilization during exercise.