Designing a fluorescence padlock probe-based biosensor and colorimetric assay for the detection of G12D KRAS mutation.

Aim: Cell-free DNA in the plasma is known to be a potential biomarker for noninvasive diagnosis of oncogenic mutations. The authors aimed to design an optimized padlock probe-based hyperbranched rolling circle amplification biosensor to detect the KRAS G12D mutation using fluorescence and colorimetric methods. Methods: Single-factor experiments, Plackett-Burman design and response surface methodology were applied to optimize the padlock probe-based hyperbranched rolling circle amplification reaction. Results: The maximum fluorescence intensity was achieved at a padlock probe concentration of 1.5 pM and target concentration of 9 pM at 38°C ligation temperature. The proposed biosensor has a low detection limit of 60 fM of target DNA and a linear response in the concentration range of 60 fM to 0.2 pM. Conclusion: The results indicated the power of these assays to detect KRAS point mutations in liquid state reactions.

Colonic Mucosal Infiltration of IgG4 Plasma Cells and Ulcerative Colitis: Determinant of Presence, Activity, Extension, and Duration of Disease.

BACKGROUND Infiltration of IgG4 positive plasma cells has been detected in the colonic mucosa of patients with ulcerative colitis (UC). The aim of the study was to investigate the association between colonic mucosal infiltration of IgG4 plasma cells and the presence, activity, extension, and duration of UC. METHODS In this case-control study (2009-2014), 102 subjects (84 with UC/18 controls) were enrolled. Clinical records and rectosigmoid biopsies of UC patients were selected, and biopsies were stained with IgG4 monoclonal antibodies. IgG4 positive plasma cells were counted by a single pathologist. RESULTS Amongst 84 patients with UC, 73.8% had UC without primary sclerosing cholangitis (PSC), and 26.2% had UC with PSC. IgG4 plasma cells were seen in 35 (41.7%) patients with UC and 0% of controls (p = 0.001). The mean amount of IgG4 containing plasma cells was significantly different between active and inactive patients with UC, although it was not significantly different between UC patients with and without PSC. The presence of IgG4 infiltration was significantly associated with the extension and duration of the disease. Furthermore, IgG4 count had a sensitivity/specificity of 78.6%/83.3% for the diagnosis of UC. CONCLUSION Our study revealed the diagnostic role of IgG4 plasma cells in the colonic mucosa of patients with UC and its association with activity, extension, and duration of disease.

Long term diarrhoea caused by simultaneous Crohn's disease and coeliac disease in the same patient.

Coeliac disease and Crohn's disease are among the most well known gastrointestinal disorders, with distinct pathogenic mechanisms. However, because of some overlapping features between these two conditions, there may be some inevitable misdiagnoses. In addition, diarrhoea and changes in bowel habit may lead the physician to misdiagnose more common disorders such as irritable bowel syndrome. There are a few cases reporting both coeliac and Crohn's disease in the same patient. Here we report a case of a 32-year-old woman suffering from long term diarrhoea who was eventually discovered to have coeliac disease and Crohn's disease simultaneously.