Centromere that plays a pivotal role in chromosome segregation is composed of repetitive elements in many eukaryotes. Although chromosomal regions containing repeats are the hotspots of rearrangements, little is known about the stability of centromere repeats. Here, by using a minichromosome that has a complete set of centromere sequences, we have developed a fission yeast system to detect gross chromosomal rearrangements (GCRs) that occur spontaneously. Southern and comprehensive genome hybridization analyses of rearranged chromosomes show two types of GCRs: translocation between homologous chromosomes and formation of isochromosomes in which a chromosome arm is replaced by a copy of the other. Remarkably, all the examined isochromosomes contain the breakpoint in centromere repeats, showing that isochromosomes are produced by centromere rearrangement. Mutations in the Rad3 checkpoint kinase increase both types of GCRs. In contrast, the deletion of Rad51 recombinase preferentially elevates isochromosome formation. Chromatin immunoprecipitation analysis shows that Rad51 localizes at centromere around S phase. These data suggest that Rad51 suppresses rearrangements of centromere repeats that result in isochromosome formation.

Background: Once DNA repair is completed, the DNA damage checkpoint is terminated, and the cell cycle is resumed. Results: Src inhibition induced a delay in G 2 checkpoint recovery and persistent ATR-Chk1 activation. Conclusion: Src inhibits ATR signaling to promote recovery from G 2 checkpoint arrest. Significance: Src sends a termination signal between the completion of DNA repair and the initiation of checkpoint termination.

The effects of various protease inhibitors on the stability of leucine enkephalin (Leu-Enk) and [D-Ala2,D-Leu5] enkephalin (DADLE) were investigated, and the permeability of these peptides was also examined in an in vitro Ussing chamber. Captopril, thiorphan, bacitracin, bestatin, puromycin, amastatin, and sodium glycocholate (Na-GC) were chosen as protease inhibitors. Regional differences in the stability of Leu-Enk and DADLE were observed, and the rank order of the stability of these peptides was colon > duodenum > ileum > jejunum. Na-GC, amastatin, and puromycin were effective protease inhibitors for improving the stability of these peptides, although captopril and thiorphan did not improve the stability of Leu-Enk. In the transport studies, Leu-Enk did not cross the intestinal membrane in the absence of protease inhibitors, but its transport was improved in the presence of Na-GC. In addition, Na-GC, amastatin, and puromycin improved the permeability of DADLE in both jejunum and colon, while the permeability of DADLE was not improved by the addition of captopril, thiorphan, and bestatin. Furthermore, the permeability of 6-carboxyfluorescein, a poorly absorbable and stable compound, was also improved in the presence of Na-GC and bacitracin at a concentration of 10 mM. These findings indicated that amastatin, puromycin, and Na-GC at a concentration of 0.5 mM might increase the permeability of DADLE due to the improved stability of DADLE in the donor site. However, Na-GC and bacitracin at a concentration of 10 mM had absorption-enhancing activities which might be also related to the enhanced permeability of DADLE across the intestinal membrane.

Background Carbon monoxide causes electrical, functional, and morphological changes in the heart. It is unclear, however, whether the indicators of myocardial damage can predict the patient’s prognosis after carbon monoxide poisoning. This retrospective study aimed to investigate the relationship between the carboxyhemoglobin level and electrocardiographic (ECG) changes and whether the ECG changes and troponin I levels are related to the patient’s prognosis after carbon monoxide poisoning. Methods Carboxyhemoglobin, troponin I, and ECG parameters were measured in 70 patients with carbon monoxide poisoning. The QT and RR intervals were measured for each ECG lead in all patients, and the corrected QT interval and corrected QT dispersion were calculated. Results The correlation between the maximum corrected QT interval and the carboxyhemoglobin level was significant (P = 0.0072, R2 = 0.1017), as were the relationships between QT dispersion and carboxyhemoglobin (P < 0.001, R2 = 0.2358) and the corrected QT dispersion and carboxyhemoglobin (P < 0.001, R2 = 0.2613). The multivariate logistic analysis showed that the significant predictors of sequential disability were corrected QT dispersion (P = 0.0042), and troponin I level (P = 0.0021). Conclusions Patients’ prognosis following carbon monoxide poisoning can be predicted based on corrected QT dispersion and the troponin I level. Patients with myocardial damage should be monitored not only for their cardiovascular outcome but also for their neurological outcome and their prognosis.

No abstract