Quantitative Analysis of Diubiquitin Isomers Using Ion Mobility-Mass Spectrometry

The diversity of ubiquitin modifications calls for methods to better characterize ubiquitin chain linkage, length, and morphology. Here, we use multiple linear regression analysis coupled with ion mobility mass spectrometry (IM-MS) to quantify the relative abundance of different ubiquitin dimer isomers. We demonstrate the utility and robustness of this approach by quantifying the relative abundance of different ubiquitin dimers in complex mixtures and comparing the results to the standard, bottom-up ubiquitin AQUA method. Our results provide a foundation for using multiple linear regression analysis and IM-MS to characterize more complex ubiquitin chain architectures

Determination of Brain Tissue Samples Storage Conditions for Reproducible Intraoperative Lipid Profiling

Ex-vivo molecular profiling has recently emerged as a promising method for intraoperative tissue identification, especially in neurosurgery. The short-term storage of resected samples at room temperature is proposed to have negligible influence on the lipid molecular profiles. However, a detailed investigation of short-term molecular profile stability is required to implement molecular profiling in a clinic. This study evaluates the effect of storage media, temperature, and washing solution to determine conditions that provide stable and reproducible molecular profiles, with the help of ambient ionization mass spectrometry using rat cerebral cortex as model brain tissue samples. Utilizing normal saline for sample storage and washing media shows a positive effect on the reproducibility of the spectra; however, the refrigeration shows a negligible effect on the spectral similarity. Thus, it was demonstrated that up to hour-long storage in normal saline, even at room temperature, ensures the acquisition of representative molecular profiles using ambient ionization mass spectrometry

Recognition of S···Cl Chalcogen Bonding in Metal-Bound Alkylthiocyanates

Reaction of K₂[PtCl₄] with excess AlkSCN in water gives the alkylthiocyanate complexes <i>trans</i>-[PtCl₂­(AlkSCN)₂] (Alk = Et <b>1</b>, ^<i>n</i>Pr <b>2</b>; 80–85%). These species were studied, in particular, by X-ray crystallography. In the solid state, both <b>1</b> and <b>2</b> exhibit the previously unreported S···Cl chalcogen bonding, which consolidates the complexes into networks and leads to layered structures. Theoretical density functional theory calculations and Bader’s atoms in molecules analysis demonstrated two types of intermolecular interactions in tetramer (<b>1</b>)₄, viz. the S···Cl chalcogen and the H···Cl hydrogen bonds. Despite that each particular S···Cl or H···Cl bonding is weak with the estimated energy of 1–2 kcal/mol, altogether they play a crucial role in the stabilization of the S₂Cl₂ fragment in (<b>1</b>)₄, the basis set of superposition error corrected interaction energy being −12.8 kcal/mol per monomer complex molecule. The chalcogen bonding and the rhomboidal structure of the S₂Cl₂ fragment can be interpreted in terms of electrostatic arguments as a result of the interaction between the belt of negative electrostatic potential around the Cl atoms and the sulfur σ-holes. The natural bond orbital analysis revealed that both LP­(S) → LP*­(Pt)/​σ*­(Pt–N)/​σ*­(Pt–Cl) and LP­(Cl) → σ*­(S–C) types of hyperconjugative charge transfers are important in the chalcogen bonding

Stoma-free Survival After Rectal Cancer Resection With Anastomotic Leakage: Development and Validation of a Prediction Model in a Large International Cohort.

Objective:To develop and validate a prediction model (STOMA score) for 1-year stoma-free survival in patients with rectal cancer (RC) with anastomotic leakage (AL).Background:AL after RC resection often results in a permanent stoma.Methods:This international retrospective cohort study (TENTACLE-Rectum) encompassed 216 participating centres and included patients who developed AL after RC surgery between 2014 and 2018. Clinically relevant predictors for 1-year stoma-free survival were included in uni and multivariable logistic regression models. The STOMA score was developed and internally validated in a cohort of patients operated between 2014 and 2017, with subsequent temporal validation in a 2018 cohort. The discriminative power and calibration of the models' performance were evaluated.Results:This study included 2499 patients with AL, 1954 in the development cohort and 545 in the validation cohort. Baseline characteristics were comparable. One-year stoma-free survival was 45.0% in the development cohort and 43.7% in the validation cohort. The following predictors were included in the STOMA score: sex, age, American Society of Anestesiologist classification, body mass index, clinical M-disease, neoadjuvant therapy, abdominal and transanal approach, primary defunctioning stoma, multivisceral resection, clinical setting in which AL was diagnosed, postoperative day of AL diagnosis, abdominal contamination, anastomotic defect circumference, bowel wall ischemia, anastomotic fistula, retraction, and reactivation leakage. The STOMA score showed good discrimination and calibration (c-index: 0.71, 95% CI: 0.66-0.76).Conclusions:The STOMA score consists of 18 clinically relevant factors and estimates the individual risk for 1-year stoma-free survival in patients with AL after RC surgery, which may improve patient counseling and give guidance when analyzing the efficacy of different treatment strategies in future studies