[The assessment of the regularity of the nephron anlage tubule formation on the basis of provisionality principle].

The study of the definitive kidneys of 94 human embryos and fetuses at 4.5 to 12 weeks of gestation, has demonstrated that the formation of the proximal nephron tubules resulted from the cellular proliferation in the area of transition of the capsule of the renal corpuscle into the tubular part of the nephron that occurs only after the completion of the segregation of the renal corpuscle and the distal tubule within the nephron anlage. The formation of the renal tubules in the nephron anlage seems to be determined phylogenetically, while the initial differentiation of the distal tubule is a provisional feature.

[Provisionality phenomenon in the histo- organo- and systemogenesis].

This review summarizes the results of the study of the provisionality phenomenon in the development of the organs of the urinary system (mesonephros, metanephros) in viviparous (human, rat) and oviparous (bird) amniotes, human organs of mixed origin (pituitary, ovary, stomodeum) reparative regeneration of supporting tissues (in humans and Syrian hamster), morphogenesis of primary hepatic cancer developing against the background of superinvasive opisthorchiasis. It is shown that during the development of tissues and organs, the stages of provisional and definitive histo- and organogenesis could be determined; saltatory mechanism is typical for embryonic organogenesis (formation of cartilaginous skeletal primordia, meso- and metanephrons) and foci of oncogenesis. Transformation zones of the type of tissue organization in the epithelium are located in the areas of contacts of the derivatives of different embryonic primordia.

Limits on light-speed anisotropies from Compton scattering of high-energy electrons.

The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the two-sided limit of 1.

Cause of atrioventricular block in patients after heart transplantation.

Background: The precise incidence and cause of atrioventricular block (AVB) after heart transplantation remain uncertain.

Methods And Results: After surgery, immediate and follow-up electrocardiograms from 1047 consecutive patients who underwent heart transplantation were reviewed for AVB and correlated with clinical symptoms, laboratory data, rejection grade, and echocardiogram and coronary angiography findings. A total of 113 patients demonstrated various kinds of AVB; the incidence was 10.

[Exposure to chloroprene as an occupational hazard (a cohort epidemiologic study)].

A cancer epidemiological study was conducted in chloroprene workers in Yerevan. In a cohort of male workers, the total morbidity rates for all tumor patterns were significantly lower (32%) than expected, which was attributed to the effect of "the healthy worker". Risk for hepatic tumor was 3.