Activation of new replication foci under conditions of replication stress.

DNA damage, binding of drugs to DNA or a shortage of nucleotides can decrease the rate or completely halt the progress of replication forks. Although the global rate of replication decreases, mammalian cells can respond to replication stress by activating new replication origins. We demonstrate that a moderate level of stress induced by inhibitors of topoisomerase I, commencing in early, mid or late S-phase, induces activation of new sites of replication located within or in the immediate vicinity of the original replication factories; only in early S some of these new sites are also activated at a distance greater than 300 nm. Under high stress levels very few new replication sites are activated; such sites are located within the original replication regions. There is a large variation in cellular response to stress - while in some cells the number of replication sites increases even threefold, it decreases almost twofold in other cells. Replication stress results in a loss of PCNA from replication factories and a twofold increase in nuclear volume. These observations suggest that activation of new replication origins from the pool of dormant origins within replication cluster under conditions of mild stress is generally restricted to the original replication clusters (factories) active at a time of stress initiation, while activation of distant origins and new replication factories is suppressed.

Relationship between DNA damage response, initiated by camptothecin or oxidative stress, and DNA replication, analyzed by quantitative 3D image analysis.

A method of quantitative analysis of spatial (3D) relationship between discrete nuclear events detected by confocal microscopy is described and applied in analysis of a dependence between sites of DNA damage signaling (γH2AX foci) and DNA replication (EdU incorporation) in cells subjected to treatments with camptothecin (Cpt) or hydrogen peroxide (H2O2). Cpt induces γH2AX foci, likely reporting formation of DNA double-strand breaks (DSBs), almost exclusively at sites of DNA replication. This finding is consistent with the known mechanism of induction of DSBs by DNA topoisomerase I (topo1) inhibitors at the sites of collisions of the moving replication forks with topo1-DNA "cleavable complexes" stabilized by Cpt. Whereas an increased level of H2AX histone phosphorylation is seen in S-phase of cells subjected to H2O2, only a minor proportion of γH2AX foci coincide with DNA replication sites. Thus, the increased level of H2AX phosphorylation induced by H2O2 is not a direct consequence of formation of DNA lesions at the sites of moving DNA replication forks. These data suggest that oxidative stress induced by H2O2 and formation of the primary H2O2-induced lesions (8-oxo-7,8-dihydroguanosine) inhibits replication globally and triggers formation of γH2AX at various distances from replication forks. Quantitative analysis of a frequency of DNA replication sites and γH2AX foci suggests also that stalling of replicating forks by Cpt leads to activation of new DNA replication origins. © 2013 International Society for Advancement of Cytometry.

[Pharyngolaryngeal reflux as one of the causes of chronic excretory otitis media].

The objective of the present work was to study the relationship between chronic secretory otitis media (CSOM) and pharyngolaryngeal reflux (PLR). A total of 43 patients aged between 3 to 19 years presenting with CSOM were available for the examination. PLR was confirmed in 36 (83.7%) patients. A relapse of CSOM after a course of otorhinolaryngological and gastroenterological treatment developed in 6 (14.0%) patients. It is concluded that antireflux therapy should be a constituent component of CSOM therapy concomitant with gastroesophageal reflux disease.

[Effectiveness of the methods of surgical treatment of retinal detachment during the years 1983-1987]. / Skutecznosc metod operacyjnego leczenia odwarstwienia siatkówki w latch 1983-1987.

The authors made an analysis of the surgical methods in 94 cases of retinal detachment. In 36 cases it was a cerclage, in 44 an episcleral implant. In 8 patients invagination of the sclera was performed, in 3 photocoagulation as a separate intervention and in 3--cerclage with a simultaneous episcleral implant. Reattachment of the retina was achieved in 69.1% of cases.

[Influence of lithium chloride on lipid metabolism]. / Vliianie khlorida litiia na lipidnyi obmen

Lithium chloride was injected subcutaneously to mice (in amounts of 500 and 300 mg/kg) once a day for 10 and 15 days, and to rabbits in single doses via a tube into the stomach (in amounts of 400 and 850 mg/kg). After different time intervals following a single or course-wise administration of the compound the level of total lipids was determined in the muscles and liver of the mice, and of the total lipids, beta-lipoproteins, phospholipids, cholesterol, fatty acids and 11-oxycorticosteroids levels in the blood serum of rabbits and of the bile acids content in the vesical bile of these animals. Hyperlipemia that developed under the effect of lithium was caused by mobilization of fat from fat depots and by deranged interstitial lipids metabolism.

[Influence of polychlorpinene on the cholate forming and conjugating functions of the liver]. / Vliianie polikhlorpinena na kholatoobrazuiushchuiu i kon'iugiruiushchuiu funktsii pecheni

Tests conducted with 69 rabbits ascertained a marked influence of acute and chronic poisoning with polychlorpinene on the synthesis and conjugation of bile acids with glycine and taurine. In cases of acute poisoning there was observed an inhibition of the bile acids synthesis, while in chronic poisoning there occurred an insignificant activation of the latter. In acute poisoning the conjugating function of the liver is grossly upset in regard to taurine and glycine and in chronic poisoning-to glycine.