Changing practices in septorhinoplasty: the Irish experience.

PURPOSE: Septorhinoplasty (SR) is one of the most complex surgical procedures of the head and neck. As an elective procedure aiming to enhance patient quality of life, it can be difficult to perform in single-payer healthcare systems due to capacity pressures from acute and oncological surgical demand. We aimed to review national trends in the practice of SR to inform future healthcare planning. METHODS: This was a cross-sectional, population-based, longitudinal study of SR cases in Ireland's single-payer (public) healthcare system from 2005 to 2021. Time-series analysis using a linear regression model was performed to analyse trends by operation type, revision rates and length of stay. The impact of the COVID-19 pandemic and introduction of national surgical guidelines was analysed. RESULTS: 1952 SR were performed. Annual mean cases declined in both real (r = - 0.76, p < 0.01) and relative (r = - 0.87, p < 0.01) terms by 31% and 43%, respectively. Ambulatory SR, while initially rarely performed, increased to account for 55% of cases performed. The mean hospital length of stay declined significantly (r = - 0.84, p < 0.01) by 44%. CONCLUSIONS: SR increasingly struggles to find its place in Ireland's public healthcare system. New changes in SR practices including the rapid growth of ambulatory surgery and shorter lengths of hospital stay indicate positive responses to the mounting pressures faced by healthcare systems.

Non-conventional laryngeal malignancies: a multicentre review of management and outcomes.

PURPOSE: Non-conventional laryngeal malignancies (NSCC) often have limited published data to guide management despite individual histopathological subtypes often exhibiting heterogeneous behaviour, characteristics, and treatment responses compared to laryngeal squamous cell carcinoma (SCC). This study aimed to compare oncological outcomes with SCC, specifically disease-free survival (DFS), disease-specific survival (DSS) and overall survival (OS). Secondary objectives were to compare treatment differences and perform a state of the art review. METHODS: This was a multicentre retrospective cohort study at four tertiary head and neck centres. Survival outcomes between NSCC and SCC patients were analysed with Kaplan-Meier curves and compared by log rank testing. Univariate Cox regression analysis was performed to predict survival by histopathological subgroup, T-stage, N-stage and M-stage. RESULTS: There were no significant differences in 3-year DFS (p = 0.499), DSS (p = 0.329), OS (p = 0.360) or Kaplan Meier survival curves (DSS/OS) between SCC and overall NSCC groups. However, univariate Cox regression analysis identified "rare" histopathologies (mostly small cell carcinoma) to be predictive of less favourable OS (p = 0.035) but this result was not observed for other NSCC histopathological subgroups. N-stage (p = 0.027) and M-stage (p = 0.048) also predicted OS for NSCC malignancies. Significant differences in treatment modalities were identified with treatment of NSCC typically involving surgical resection and SCC often managed non-surgically (e.g., primary radiotherapy). CONCLUSIONS: Although overall NSCC is managed differently compared to SCC, there do not appear to be differences in survival outcomes between these groups. N-stage and M-stage appear to be more predictive of OS than histopathology than many NSCC subtypes.

Differential modes of DNA binding by mismatch uracil DNA glycosylase from Escherichia coli: implications for abasic lesion processing and enzyme communication in the base excision repair pathway.

Mismatch uracil DNA glycosylase (Mug) from Escherichia coli is an initiating enzyme in the base-excision repair pathway. As with other DNA glycosylases, the abasic product is potentially more harmful than the initial lesion. Since Mug is known to bind its product tightly, inhibiting enzyme turnover, understanding how Mug binds DNA is of significance when considering how Mug interacts with downstream enzymes in the base-excision repair pathway. We have demonstrated differential binding modes of Mug between its substrate and abasic DNA product using both band shift and fluorescence anisotropy assays. Mug binds its product cooperatively, and a stoichiometric analysis of DNA binding, catalytic activity and salt-dependence indicates that dimer formation is of functional significance in both catalytic activity and product binding. This is the first report of cooperativity in the uracil DNA glycosylase superfamily of enzymes, and forms the basis of product inhibition in Mug. It therefore provides a new perspective on abasic site protection and the findings are discussed in the context of downstream lesion processing and enzyme communication in the base excision repair pathway.

Mismatch uracil glycosylase from Escherichia coli: a general mismatch or a specific DNA glycosylase?

The gene for the mismatch-specific uracil glycosylase (MUG) was identified in the Escherichia coli genome as a sequence homolog of the mammalian thymine DNA glycosylase, with activity against uracil in U.G mismatches. Subsequently, 3,N4-ethenocytosine (epsilonC), thymine, 5-hydroxymethyluracil, and 8-(hydroxymethyl)-3,N4-ethenocytosine have been proposed as possible substrates for this enzyme. The evaluation of various DNA adducts as substrates is complicated by the biphasic nature of the kinetics of this enzyme. Our results demonstrate that product release by the enzyme is very slow and hence comparing the "steady-state" parameters of the enzyme for different substrates is of limited use. Consequently, the ability of the enzyme to excise a variety of damage products of purines and pyrimidines was studied under single turnover conditions. Although the enzyme excised both epsilonC and U from DNA, the former adduct was significantly better as a substrate in terms of binding and hydrolysis. Some products of oxidative and alkylation damage are also moderately good substrates for the enzyme, but thymine is a poor substrate. This comparison of different substrates under single turnover conditions provides a rational basis for comparing substrates of MUG and we relate these conclusions to the known crystal structures of the enzyme and its catalytic mechanism.