Interactions of cytotoxic amino acid derivatives of tert-butylquinone with DNA and lysozyme

The interactions of nine amino acid derivatives of tert-butylquinone with biomacromolecules were studied. Sodium dodecyl sulphate (SDS) gel electrophoresis and mass spectrometry confirmed the absence of modifications of lysozyme by any of the synthesized compounds. Spectrophotometric studies demonstrated hyperchromism, i.e., the existence of interactions between the quinones and calf thymus DNA (CT-DNA). Determination of the binding constants by absorption titration indicated weak interactions between the quinone derivatives and CT-DNA. The quenching of fluorescence of the intercalator ethidium bromide (EB) from the EB-CT-DNA system and of the minor groove binder Hoechst 33258 (H) from the H-CT-DNA system by the synthesized derivatives indicated interactions of the compounds and CT-DNA. Circular dichroism (CD) spectra demonstrated a non-intercalative binding mode of the quinone derivatives to CT-DNA. Molecular docking results confirmed binding to the minor groove. The electrophoretic pattern showed no cleavage of the pUC19 plasmid in the presence of any of the synthesized compounds. The ability of the derivatives to scavenge radicals was confirmed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. All the presented results suggest that the DNA minor groove binding is the principal mechanism of action of the examined amino acid derivatives

Effect of weekend admission on in-hospital mortality and functional outcomes for patients with acute subarachnoid haemorrhage (SAH)

BACKGROUND: Aneurysmal subarachnoid haemorrhage (aSAH) is an acute cerebrovascular event with high socioeconomic impact as it tends to affect younger patients. The recent NCEPOD study looking into management of aSAH has recommended that neurovascular units in the United Kingdom should aim to secure cerebral aneurysms within 48 h and that delays because of weekend admissions can increase the mortality and morbidity attributed to aSAH. METHOD: We used data from a prospective audit of aSAH patients admitted between January 2009 and December 2011. The baseline demographic and clinical features of the weekend and weekday groups were compared using the chi-squared test and T-test. Cox proportional hazards models (Proc Phreg in SAS) were used to calculate the adjusted overall hazard of in-hospital death associated with admission on weekend, adjusting for age, sex, baseline WFNS grade, type of treatment received and time from scan to treatment. Sliding dichotomy analysis was used to estimate the difference in outcomes after SAH at 3 months in weekend and weekday admissions. RESULTS: Those admitted on weekends had a significantly higher scan to treatment time (83.05 ± 83.4 h vs 40.4 ± 53.4 h, P < 0.0001) and admission to treatment (71.59 ± 79.8 h vs 27.5 ± 44.3 h, P < 0.0001) time. After adjustments for adjusted for relevant covariates weekend admission was statistically significantly associated with excess in-hospital mortality (HR = 2.1, CL [1.13–4.0], P = 0.01). After adjustments for all the baseline covariates, the sliding dichotomy analysis did not show effects of weekend admission on long-term outcomes on the good, intermediate and worst prognostic bands. CONCLUSIONS: This study provides important data showing excess in-hospital mortality of patients with SAH on weekend admissions served by the United Kingdom’s National Health Service.; However, there were no effects of weekend admission on long-term outcomes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00701-016-2746-z) contains supplementary material, which is available to authorized users

Elongation factor ELOF1 drives transcription-coupled repair and prevents genome instability

Correct transcription is crucial for life. However, DNA damage severely impedes elongating RNA polymerase II, causing transcription inhibition and transcription-replication conflicts. Cells are equipped with intricate mechanisms to counteract the severe consequence of these transcription-blocking lesions. However, the exact mechanism and factors involved remain largely unknown. Here, using a genome-wide CRISPR-Cas9 screen, we identified the elongation factor ELOF1 as an important factor in the transcription stress response following DNA damage. We show that ELOF1 has an evolutionarily conserved role in transcription-coupled nucleotide excision repair (TC-NER), where it promotes recruitment of the TC-NER factors UVSSA and TFIIH to efficiently repair transcription-blocking lesions and resume transcription. Additionally, ELOF1 modulates transcription to protect cells against transcription-mediated replication stress, thereby preserving genome stability. Thus, ELOF1 protects the transcription machinery from DNA damage via two distinct mechanisms