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Abstract
Background and aims: Intestinal adaptation in short bowel syndrome (SBS) includes morphologic processes and functional mechanisms. This study investigated whether digestive enzyme expression in the duodenum and colon is upregulated in SBS patients. Method: Sucrase‐isomaltase (SI), lactase‐phlorizin hydrolase (LPH), and neutral Aminopeptidase N (ApN) were analyzed in duodenal and colonic biopsies from nine SBS patients in a late stage of adaptation as well as healthy and disease controls by immunoelectron microscopy (IEM), Western blots, and enzyme activities. Furthermore, proliferation rates and intestinal microbiota were analyzed in the mucosal specimen. Results: We found significantly increased amounts of SI, LPH, and ApN in colonocytes in most SBS patients with large variation and strongest effect for SI and ApN. Digestive enzyme expression was only partially elevated in duodenal enterocytes due to a low proliferation level measured by Ki‐67 staining. Microbiome analysis revealed high amounts of Lactobacillus resp. low amounts of Proteobacteria in SBS patients with preservation of colon and ileocecal valve. Colonic expression was associated with a better clinical course in single cases. Conclusion: In SBS patients disaccharidases and peptidases can be upregulated in the colon. Stimulation of this colonic intestinalization process by drugs, nutrients, and pre‐ or probiotics might offer better therapeutic approaches.
One of the most common mutations in the serine protease inhibitor Kazal type 1 (SPINK1) gene is the N34S variant which is strongly associated with chronic pancreatitis. Although it is assumed that N34S mutation constitutes a high-risk factor, the underlying pathologic mechanism is still unknown. In the present study, we investigated the impact of physiological stress factors on SPINK1 protein structure and trypsin inhibitor function using biophysical methods. Our circular dichroism spectroscopy data revealed differences in the secondary structure of SPINK1 and N34S mutant suggesting protein structural changes induced by the mutation as an impairment that could be disease-relevant. We further confirmed that both SPINK1 (KD of 0.15 ± 0.06 nM) and its N34S variant (KD of 0.08 ± 0.02 nM) have similar binding affinity and inhibitory effect towards trypsin as shown by surface plasmon resonance and trypsin inhibition assay studies, respectively. We found that stress conditions such as altered ion concentrations (i.e. potassium, calcium), temperature shifts, as well as environmental pH lead to insignificant differences in trypsin inhibition between SPINK1 and N34S mutant. However, we have shown that the environmental pH induces structural changes in both SPINK1 constructs in a different manner. Our findings suggest protein structural changes in the N34S variant as an impairment of SPINK1 and environmental pH shift as a trigger that could play a role in disease progression of pancreatitis.
Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers. Acquired inherited and/or somaticmutations drive its development. In order to prevent the formation of these mutations, precise and immediaterepair of any DNA damage is indispensable. Non-homologous end-joining (NHEJ) is the key mechanism of DNAdouble-strand break repair. Here, we report that miR-502 targets two components in pancreatic cell lines, Ku70and XLF of the C-NHEJ. Interestingly, we also observed an attenuated cell cycle response to gamma ionizingradiation (γ-IR) via diminished phosphorylation of checkpoint kinase 1 (Chk1) on serine 345 in these cell lines.Altogether, pancreatic cells showed increased susceptibility toγ-IR via direct inhibition of DNA double-strandbreak repair and attenuation of the cell cycle response.
Abstract
Introduction
Transabdominal ultrasound (US) and magnetic resonance imaging (MRI) are commonly used for the examination of the pancreas in clinical routine. We therefore were interested in the concordance of these two imaging methods for the size measurement of the pancreas and how age, gender, and body mass index (BMI) affect the organ size.
Methods
A total of 342 participants from the Study of Health in Pomerania underwent whole‐body MRI and transabdominal US on the same day, and the diameter of the pancreatic head, body, and tail were measured. The agreement between US and MRI measurements was assessed by Bland and Altman plots. Intraclass correlation coefficients were used to compare observers. A multivariable regression model was applied using the independent variables age, gender, and body mass index.
Results
Compared to MRI, abdominal US returned smaller values for each segment of the pancreas, with a high level of inconsistency between these two methods. The mean difference was 0.39, 0.18, and 0.54 cm for the head, body, and tail, respectively. A high interobserver variability was detected for US. Multivariable analysis showed that pancreatic size in all three segments increased with BMI in both genders whereas pancreatic head and tail size decreased with age, an effect more marked in women.
Conclusions
Agreement of pancreatic size measurements is poor between US and MRI. These limitations should be considered when evaluating morphologic features for pathologic conditions or setting limits of normal size. Adjustments for BMI, gender, and age may also be warranted.