MICB0106 gene polymorphism is associated with ulcerative colitis in central China

Background: The highly polymorphic nonclassical MHC class I chain-related genes A and B (MICA and MICB) encode stress-inducible glycoproteins expressed on various epithelial cells including intestinal epithelial cells. MICA and MICB gene polymorphisms and expressions are associated with autoimmune diseases but not known in ulcerative colitis (UC). Aims: To investigate the association of MICB exon 2-4 polymorphisms and soluble MICA (sMICA) expression with the susceptibility of UC in central China. Materials and methods: Genomic DNA was isolated from peripheral blood. The allele frequencies of MICB exon 2-4 were genotyped in 105 UC patients and 213 healthy controls by PCR single-stranded conformation polymorphism method. Thirty-two patients and 32 controls were selected for determining serum sMICA expression by ELISA. Results: Allele frequency of MICB0106 was significantly higher in UC patients than in healthy controls (19.0% vs. 8.9%, corrected P (Pc)=0.0006), especially in patients with extensive colitis (24.4% vs. 8.9%, Pc=0.0006), moderate and severe disease (24.1% vs. 8.9%, Pc=0.0006), extraintestinal manifestations (20.5% vs. 8.9%, Pc=0.012), male patients (22.1% vs. 8.0%, Pc=0.006), and patients over the age of 40 years (28.8% vs. 8.3%, Pc=0.0006). The sMICA level was significantly higher in UC than in healthy controls (604.41±480.43 pg/ml vs. 175.37±28.31 pg/ml, P=0.0001) but not associated with the MICB0106 genotypes. Conclusions: Overall, MICB0106 allele was positively associated with UC in the Han Chinese in central China. sMICA was highly expressed in UC but not associated with the MICB0106 genotype

A cautionary note on the impact of protocol changes for genome-wide association SNP × SNP interaction studies: an example on ankylosing spondylitis

peer reviewedGenome-wide association interaction (GWAI) studies have increased in popularity. Yet to date, no standard protocol exists. In practice, any GWAI workflow involves making choices about quality control strategy, SNP filtering, linkage disequilibrium (LD) pruning, analytic tool to model or to test for genetic interactions. Each of these can have an impact on the final epistasis findings and may affect their reproducibility in follow-up analyses. Choosing an analytic tool is not straightforward, as different such tools exist and current understanding about their performance is based on often very particular simulation settings. In the present study, we wish to create awareness for the impact of (minor) changes in a GWAI analysis protocol can have on final epistasis findings. In particular, we investigate the influence of marker selection and marker prioritization strategies, LD pruning and the choice of epistasis detection analytics on study results, giving rise to 8 GWAI protocols. Discussions are made in the context of the ankylosing spondylitis (AS) data obtained via the Wellcome Trust Case Control Consortium (WTCCC2). As expected, the largest impact on AS epistasis findings is caused by the choice of marker selection criterion, followed by marker coding and LD pruning. In MB-MDR, co-dominant coding of main effects is more robust to the effects of LD pruning than additive coding. We were able to reproduce previously reported epistasis involvement of HLA-B and ERAP1 in AS pathology. In addition, our results suggest involvement of MAGI3 and PARK2, responsible for cell adhesion and cellular trafficking. Gene Ontology (GO) biological function enrichment analysis across the 8 considered GWAI protocols also suggested that AS could be associated to the Central Nervous System (CNS) malfunctions, specifically, in nerve impulse propagation and in neurotransmitters metabolic processes

Effect of Intraoperative High Positive End-Expiratory Pressure (PEEP) with Recruitment Maneuvers vs Low PEEP on Postoperative Pulmonary Complications in Obese Patients: A Randomized Clinical Trial

Importance: An intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients undergoing surgery, but the effect on clinical outcomes is uncertain. Objective: To determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with a lower level of PEEP. Design, Setting, and Participants: Randomized clinical trial of 2013 adults with body mass indices of 35 or greater and substantial risk for postoperative pulmonary complications who were undergoing noncardiac, nonneurological surgery under general anesthesia. The trial was conducted at 77 sites in 23 countries from July 2014-February 2018; final follow-up: May 2018. Interventions: Patients were randomized to the high level of PEEP group (n = 989), consisting of a PEEP level of 12 cm H2O with alveolar recruitment maneuvers (a stepwise increase of tidal volume and eventually PEEP) or to the low level of PEEP group (n = 987), consisting of a PEEP level of 4 cm H2O. All patients received volume-controlled ventilation with a tidal volume of 7 mL/kg of predicted body weight. Main Outcomes and Measures: The primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Among the 9 prespecified secondary outcomes, 3 were intraoperative complications, including hypoxemia (oxygen desaturation with Spo2 ≤92% for >1 minute). Results: Among 2013 adults who were randomized, 1976 (98.2%) completed the trial (mean age, 48.8 years; 1381 [69.9%] women; 1778 [90.1%] underwent abdominal operations). In the intention-to-treat analysis, the primary outcome occurred in 211 of 989 patients (21.3%) in the high level of PEEP group compared with 233 of 987 patients (23.6%) in the low level of PEEP group (difference, -2.3% [95% CI, -5.9% to 1.4%]; risk ratio, 0.93 [95% CI, 0.83 to 1.04]; P =.23). Among the 9 prespecified secondary outcomes, 6 were not significantly different between the high and low level of PEEP groups, and 3 were significantly different, including fewer patients with hypoxemia (5.0% in the high level of PEEP group vs 13.6% in the low level of PEEP group; difference, -8.6% [95% CI, -11.1% to 6.1%]; P <.001). Conclusions and Relevance: Among obese patients undergoing surgery under general anesthesia, an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers, compared with a strategy with a lower level of PEEP, did not reduce postoperative pulmonary complications. Trial Registration: ClinicalTrials.gov Identifier: NCT02148692