BackgroundElevated microsatellite alterations at selected tetranucleotide repeats (EMAST) is a genetic signature observed in 60% of sporadic colorectal cancers (CRCs). Unlike microsatellite unstable CRCs where hypermethylation of the DNA mismatch repair (MMR) gene hMLH1’s promoter is causal, the precise cause of EMAST is not clearly defined but points towards hMSH3 deficiency.AimTo examine if hMSH3 deficiency causes EMAST, and to explore mechanisms for its deficiency.MethodsWe measured −4 bp framshifts at D8S321 and D20S82 loci within EGFP-containing constructs to determine EMAST formation in MMR-proficient, hMLH1−/−, hMSH6−/−, and hMSH3−/− CRC cells. We observed the subcellular location of hMSH3 with oxidative stress.Results D8S321 mutations occurred 31-and 40-fold higher and D20S82 mutations occurred 82-and 49-fold higher in hMLH1−/− and hMSH3−/− cells, respectively, than in hMSH6−/− or MMR-proficient cells. hMSH3 knockdown in MMR-proficient cells caused higher D8S321 mutation rates (18.14 and 11.14×10−4 mutations/cell/generation in two independent clones) than scrambled controls (0 and 0.26×10−4 mutations/cell/generation; p<0.01). DNA sequencing confirmed the expected frameshift mutations with evidence for ongoing mutations of the constructs. Because EMAST-positive tumors are associated with inflammation, we subjected MMR-proficient cells to oxidative stress via H2O2 to examine its effect on hMSH3. A reversible nuclear-to-cytosol shift of hMSH3 was observed upon H2O2 treatment.ConclusionEMAST is dependent upon the MMR background, with hMSH3−/− more prone to frameshift mutations than hMSH6−/−, opposite to frameshift mutations observed for mononucleotide repeats. hMSH3−/− mimics complete MMR failure (hMLH1−/−) in inducing EMAST. Given the observed heterogeneous expression of hMSH3 in CRCs with EMAST, hMSH3-deficiency appears to be the event that commences EMAST. Oxidative stress, which causes a shift of hMSH3’s subcellular location, may contribute to an hMSH3 loss-of-function phenotype by sequestering it to the cytosol.

<b><i>Background:</i></b> Fractional exhaled nitric oxide (FeNO) is a surrogate marker for airway inflammation, supporting the diagnostic pathway and treatment decisions for asthma patients. <b><i>Objectives:</i></b> Aim of this study was to compare the new analyser Vivatmo pro (Bosch, BV) with NIOX VERO (Circassia, CN) and CLD (Ecomedics, EC). <b><i>Methods:</i></b> In 100 asthmatics (median 53 years [range 20–87], 62% female, 86% on inhaled corticosteroids [mean 1,300 μg beclomethasone dipropionate or equivalent], 35% treated with biologics) 2 FeNO measurements per device were performed. Additionally, the success rate to achieve a valid NO value was evaluated. <b><i>Results:</i></b> Sixty-eight percent of the patients had FeNO values below 50 ppb. Median NO concentrations were 31 ppb (range 6–194) for BV, 33 ppb (9–164) for CN and 31ppb (7–353) for EC. Bland-Altman plots suggested an agreement within the predefined limits of ±5 ppb for all analysers within the therapeutically relevant range (0–70 ppb). The highest agreement in FeNO levels were between BV and EC with mean differences of –0.26 (95% CI –1.48 to 0.95) vs. 1.52 (95% CI 0.4–2.6) ppb for CN and EC. The results indicate an equivalence of the methods (two-one sided <i>t</i> test-equivalence test: <i>p</i> &#x3c; 0.0001, ±5 ppb margins). Acceptance of the measurements was high for all devices (97%). The highest success rate to obtain 2 valid NO values without failed attempts was achieved with the BV analyser (73 vs. 62% for the CN analyser and 46% for the EC analyser). <b><i>Conclusions:</i></b> For the range between 0 and 70 ppb, FeNO concentrations measured with all 3 devices were statistically equivalent within predefined acceptance criteria and did not differ in a clinically relevant way.

Due to misunderstandings about their effectiveness and feasibility, topical (or rectal) therapies with aminosalicylates (5-aminosalicylic acid, 5-ASA) and steroids are often underused in patients with ulcerative colitis (UC). However, many of these patients could be treated solely with rectal/topical therapies, or could benefit from them in combination with oral therapies. We review the evidence for topical therapies containing 5-ASA and budesonide in UC and discuss how these therapies can be optimized in daily practice, thereby improving compliance. Finally, we provide a brief summary of studies on the use of other topical treatments in UC, the results of which were both promising and negative.

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