Investigation of osmolyte effects on FolM: comparison with other dihydrofolate reductases.

A weak association between osmolytes and dihydrofolate (DHF) decreases the affinity of the substrate for the Escherichia coli chromosomal and R67 plasmid dihydrofolate reductase (DHFR) enzymes. To test whether the osmolyte-DHF association also interferes with binding of DHF to FolM, an E. coli enzyme that possesses weak DHFR activity, ligand binding was monitored in the presence of osmolytes. The affinity of FolM for DHF, measured by kcat/Km(DHF), was decreased by the addition of an osmolyte. Additionally, binding of the antifolate drug, methotrexate, to FolM was weakened by the addition of an osmolyte. The changes in ligand binding with water activity were unique for each osmolyte, indicating preferential interaction between the osmolyte and folate and its derivatives; however, additional evidence provided support for further interactions between FolM and osmolytes. Binding of the reduced nicotinamide adenine dinucleotide phosphate (NADPH) cofactor to FolM was monitored by isothermal titration calorimetry as a control for protein-osmolyte association. In the presence of betaine (proposed to be the osmolyte most excluded from protein surfaces), the NADPH Kd decreased, consistent with dehydration effects. However, other osmolytes did not tighten binding to the cofactor. Rather, dimethyl sulfoxide (DMSO) had no effect on the NADPH Kd, while ethylene glycol and polyethylene glycol 400 weakened cofactor binding. Differential scanning calorimetry of FolM in the presence of osmolytes showed that both DMSO and ethylene glycol decreased the stability of FolM, while betaine increased the stability of the protein. These results suggest that some osmolytes can destabilize FolM by preferentially interacting with the protein. Further, these weak attractions can impede ligand binding. These various contributions have to be considered when interpreting osmotic pressure results.

Mucosa-Associated Lymphoid Tissue Surgeries as a Possible Risk for Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis.

Background: Inflammatory bowel disease (IBD) is a group of chronic inflammatory gastrointestinal disorders that are caused by genetic susceptibility and environmental factors and affects a significant portion of the global population. The gut-associated lymphoid tissue (GALT) is known to play a crucial role in immune modulation and maintaining gut microbiota balance. Dysbiosis in the latter has a known link to IBD. Therefore, the increasing prevalence of adenoidectomy in children should be explored for its potential association with IBD. The objective of this paper was to assess the association between adenoid tissue removal and the risk of developing Crohn's disease (CD) and ulcerative colitis (UC). Methods: We conducted a pooled meta-analysis to evaluate the extended clinical outcomes in patients who underwent appendicectomy and tonsillectomy compared to those who did not. Our approach involved systematically searching the PubMed database for relevant observational studies written in English. We followed the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines to collect data from various time periods, and to address the diversity in study results; we employed a random-effects analysis that considered heterogeneity. For outcomes, odds ratios (ORs) were pooled using a random-effects model. Results: Seven studies, out of a total of 114,537, met our inclusion criteria. Our meta-analysis revealed a significant association between appendicectomy and CD (OR: 1.57; 95% confidence interval (CI): 1.01 - 2.43; heterogeneity I2 = 93%). Similarly, we found a significant association between tonsillectomy and CD (OR: 1.93; 95% CI: 0.96 - 3.89; I2 = 62%). However, no significant association was observed between appendicectomy and UC (OR: 0.60; 95% CI: 0.24 - 1.47; I2 = 96%), while a modest association was found between tonsillectomy and UC (OR: 1.24; 95% CI: 1.18 - 1.30; I2 = 0%). Conclusions: In summary, we found that the trend of appendicectomy is linked to higher odds of CD, and tonsillectomy is more likely associated with increased odds for both CD and UC, with a risk of bias present.