The key role of a basic domain of histone H2B N-terminal tail in the action of 5-bromodeoxyuridine to induce cellular senescence

5-Bromodeoxyuridine (BrdU), a thymidine analogue, is an interesting reagent that modulates various biological phenomena. BrdU, upon incorporation into DNA, causes destabilized nucleosome positioning which leads to changes in heterochromatin organization and gene expression in cells. We have previously shown that BrdU effectively induces cellular senescence, a phenomenon of irreversible growth arrest in mammalian cells. Identification of the mechanism of action of BrdU would provide a novel insight into the molecular mechanisms of cellular senescence. Here, we showed that a basic domain in the histone H2B N-terminal tail, termed the HBR (histone H2B repression) domain, is involved in the action of BrdU. Notably, deletion of the HBR domain causes destabilized nucleosome positioning and derepression of gene expression, as does BrdU. We also showed that the genes up-regulated by BrdU significantly overlapped with those by deletion of the HBR domain, the result of which suggested that BrdU and deletion of the HBR domain act in a similar way. Furthermore, we showed that decreased HBR domain function induced cellular senescence or facilitated the induction of cellular senescence. These findings indicated that the HBR domain is crucially involved in the action of BrdU, and also suggested that disordered nucleosome organization may be involved in the induction of cellular senescence.

Comparison of outcomes in patients with or without ARC-HBR criteria undergoing PCI with polymer-free biolimus coated stents: The BioFreedom France study

BACKGROUND

The polymer-free biolimus coated stent (BioFreedom) was shown to be superior to bare metal stents in the LEADERS FREE randomized trial in high bleeding risk (HBR) patients treated with 1-month dual antiplatelet therapy (DAPT). However, there is limited outcome data with this device in an all-comers' population.

METHODS

We conducted a prospective single-arm study of patients undergoing percutaneous coronary intervention with the polymer-free biolimus coated stent in 25 centers in France with wide inclusion criteria including multivessel disease, complex lesions, and acute coronary syndromes. The primary endpoint was the incidence of target lesion failure (TLF), a composite of cardiac death or target-vessel myocardial infarction (MI) or clinically indicated target lesion revascularization (ci-TLR) at 1-year. The patient population was classified according to the presence (or not) of HBR criteria according to the recent ARC-HBR definition.

RESULTS

Between April 2019 and April 2020, 1497 patients were enrolled. TLF occurred in 101 (6.9%) patients, including cardiac death in 35 (2.4%), target vessel MI in 20 (1.4%) and ci-TLR in 65 (4.5%) of them. There were 491 HBR patients (32.8%) and 1006 non-HBR patients. The median duration of DAPT was 74 days in the HBR group versus 348 days in the non-HBR group (p < 0.0001). TLF occurred in 44 (9.2%) of the HBR group and in 57 (5.8%) of the non-HBR group (relative risk 1.62 [95% confidence interval: 1.10-2.41], p = 0015). Compared to the non-HBR group, HBR patients had higher rates of cardiac death (4.4% vs. 1.4%, p = 0.0005) and target vessel MI (2.9% vs. 0.6%, p = 0.0003), but similar rates of ci-TLR. BARC 3-5 bleeding occurred in 6.2% of the HBR group versus 1.4% of the non-HBR group (p < 0.0001).

CONCLUSION

In this multicenter all-comers study, HBR patients treated with a polymer-free biolimus coated stent had, compared to non-HBR patients, an increased risk of cardiac death and MI, and despite a shorter duration of DAPT, continued to have higher rates of BARC 3-5 bleeding.

Relationship between land cover and Anophelinae species abundance, composition and diversity in NW Colombia

Anthropic activities, mainly deforestation, have produced rapid transformation of land cover types in the Urabá region at northwest Colombia. Land cover alterations impact the abundance and composition of the Anophelinae community, affecting malaria transmission dynamics. Therefore, this study used landscape metrics to evaluate the relationship of land cover types with Anophelinae species abundance, composition and diversity in the important malaria endemic Urabá region, in NW Colombia. Orthorectified aerial photographs were used to identify land cover types in four localities of the region. Landscape metrics were obtained and diversity indices were estimated for both, land covers and Anophelinae species collected. The impact of land cover type on the presence and abundance of Anophelinae species was evaluated using a canonical correspondence analysis. Diversity indices showed differences in the Anophelinae community and land covers. The variables with more influence in the Anophelinae community composition were locality, bare soil and the interaction between forest and bare soil covers. The most abundant and dominant species Nyssorhynchus nuneztovari (former Anopheles nuneztovari), related with impacted environments was associated with grass, shrub and bare soil land covers. In conclusion, land covers derived from anthropic activities favored the presence and abundance of the main malaria vectors; but, regardless of differences in landscape, unknown specific factors varying among localities lead to a unique configuration in each site that directly shaped anopheline community composition locally. This information is essential for the development of malaria risk maps and for the design of integrated vector control interventions that include the recognition of the landscape features favoring human-vector contact.