Respiratory electromyographic estimates of ventilatory functions in piglets

The best electromyographic (EMG) predictors of respiratory drive (P100), tidal volume (VT) and ventilation (VE) were determined from diaphragmatic (DI) and posterior cricoarytenoid (PCA) EMG measures in 8-48-day-old, anesthetized piglets. Progressive hypercapnia was employed to obtain a wide range of muscle activity. A custom-designed, microcomputer-based system was employed to measure the duration, peak amplitude, rate of rise (initial slope) as well as the summed total and initial (first 100 ms) EMG activity from the DI and the PCA. For each respiratory function, the following combinations of EMG measures were identified as significant predictors using regression analyses: (1) for P100, DI amplitude, PCA initial area and PCA rate of rise; (2) for VT, DI amplitude, PCA duration and DI duration; (3) for VE, DI amplitude, DI initial area, PCA initial area, PCA rate of rise, PCA duration, DI area and DI rate of rise. Thus, whereas the traditionally employed measure of DI amplitude is an important correlate of P100, VT or VE, a complete estimate of these respiratory functions requires the inclusion of initial EMG measures and duration.     

Serum enzyme activities in the African elephant (loxodonta africana)

The serum activities of aspartate aminotransferase, alanine aminotransferase, alpha-hydroxybutyrate dehydrogenase and creatine phosphokinase have been measured in the African elephant. In general, the values were broadly comparable with those of man except that alanine aminotransferase was much lower and creatine phosphokinase higher. No variation due to age, sex, season or location was observed.     

Morphologic disturbance of lung maturation in fetuses of alloxan diabetic rabbits

Maturation of lungs was studied morphologically in fetuses of does made diabetic with alloxan. The lungs of fetuses of does treated with alloxan 24 h after mating appeared to be less mature than control lungs, as shown by significant decrease in areal density of air space (p < 0.01) and by increases in areal density of alveolar epithelium and capillaries (p < 0.02). In alloxan fetuses, ultrastructural techniques revealed that type II cells had 10 times the control value for areal density of glycogen (p < 0.01) and 2.5 times that of rough endoplasmic reticulum (p < 0.05), but the proportion of type II cells and the number of lamellar bodies per type II cell profile were similar in both groups. Ultrastructural examination of capillaries demonstrated that their migration and the fusion of their basement membrane with that of alveolar epithelium did not occur as frequently in alloxan fetuses as in control fetuses. Biochemically, the lungs of alloxan fetuses contained significantly more glycogen and protein (p < 0.01) than control lungs, but the deoxyribonucleic acid was similar. The alloxan fetuses had a disturbance of lung structural maturation that was consistent with our previous findings of delayed functional maturation without accompanying change in disaturated phosphatidylcholine levels and ratio of lecithin to sphingomyelin.     

Bases of surgical treatment of bilateral suppurative processes in the lungs

In dogs subjected to gravitational overloadings (+Gx) according to a special training schedule the wall structure of the main arteries (carotid, humeral, femoral and aorta) was studied by histological methods. The amount of catecholamines (adrenaline and noradrenaline) in the venous blood plasma and in the adrenal tissue was the index of the sympathoadrenal system condition. It was demonstrated that in trained animals the tolerance threshold to continuously increasing overloadings (+Gx) rose. It was accompanied by an elevated amount of catecholamines in blood and the adrenals In the walls of the main arteries studied a moderate hyperelastosis and a slight collagenization of the adventitia was noted. All parts of the microcirculatory bed were moderately dilated, which favoured a better blood outflow. The data obtained demonstrate adaptational changes, which can be interpreted as indices of training and reliability of the organism.     

Teratogenic and embryotoxic activity of several 2,4-diaminopyrimidine derivatives

The degree of teratogenic and embryotoxic effects is dependent not only on the period of gestation and the agent dosage but also on the chemical structure of its molecule. In the series of derivatives of 2,4-diamino-5-phenylpyrimidine with different length of the alkul radical in the 6 position the preparation with ethyl group has the greatest injuring effect. Thus, the structural distinctions in the molecules of pharmacological agents are responsible for the selective toxicity of drugs in relation to mammalian embryos.     

The cytogenetic disorders in the people who took part in the cleanup of the sequelae at the Chernobyl Atomic Electric Power Station and who lived continuously in areas with an unfavorable ecological situation

Cytogenetic disturbances are manifested now in persons who liquidated aftereffects of the Chernobyl disaster. The character and course of the disturbances depend on the ecological conditions of the region where liquidators live at present. Examination of a group of liquidators with nerve-psychopathologic disorders and accompanying somatic pathology has revealed the presence of cytogenetic disturbances, mainly of the chromosome aberration type. At the same time, in persons who live under conditions of high environment pollution with ejections of industrial enterprises, the number of chromatid aberrations increases, which may be a result of action of chemical mutagens. A tight correlation is revealed between the level of cytogenetic disorders in lymphocytes and expressivity of the secondary immunodeficiency. Elimination of lymphocytes with unstable chromosome aberration is delayed when ecological pollution of the biosphere reaches the high level.     

Clinical trials comparing two treatment policies: which aspects of the treatment policies make a difference?

We discuss pragmatic clinical trials with survival endpoints in which subjects commonly change treatment during follow-up. Suppose that an intention-to-treat (ITT) analysis shows a significant difference between the randomized groups. We may want to ask questions about the reason for such a difference in outcome between randomized groups: for example, was the difference due to different policies for change to a third more beneficial regime? We address such questions using the semi-parametric accelerated life models of Robins, which exploit the randomization assumption fully and avoid direct comparisons of possibly differently selected subgroups. No assumption is made about the relationship of treatment actually prescribed to prognosis. A sensitivity analysis, using a range of plausible values for the causal effect of a covariate, estimates the contrasts between randomized groups that would have been observed if the covariate had universally been 0. The main technical problem is in dealing with censoring, for the method requires different degrees of recensoring for different values of the causal effect, and this can lead to estimates of low precision. The methods are applied to a randomized comparison of two anti-hypertensive treatments in which approximately half the subjects changed treatment during follow-up. Various time-dependent covariates, representing patterns of side-effects and treatments, are used in the model. We find that the observed difference in cardiovascular deaths between the randomized groups cannot be explained in this way by their different covariate patterns.