Hydrokinetic pancreatic function and insulin secretion are moduled by Cl- uniporter Slc26a9 in mice

AIM

Slc26a9 is a member of the Slc26 multifunctional anion transporter family. Polymorphisms in Slc26a9 are associated with an increased incidence of meconium ileus and diabetes in cystic fibrosis patients. We investigated the expression of Slc26a9 in the murine pancreatic ducts, islets and parenchyma, and elucidated its role in pancreatic ductal electrolyte and fluid secretion and endocrine function.

METHODS

Pancreatic Slc26a9 and CFTR mRNA expression, fluid and bicarbonate secretion were assessed in slc26a9^-/- mice and their age- and sex-matched wild-type (wt) littermates. Glucose and insulin tolerance tests were performed.

RESULTS

Compared with stomach, the mRNA expression of Slc26a9 was low in pancreatic parenchyma, 20-fold higher in microdissected pancreatic ducts than parenchyma, and very low in islets. CFTR mRNA was ~10 fold higher than Slc26a9 mRNA expression in each pancreatic cell type. Significantly reduced pancreatic fluid secretory rates and impaired glucose tolerance were observed in female slc26a9^-/- mice, whereas alterations in male mice did not reach statistical significance. No significant difference was observed in peripheral insulin resistance in slc26a9^-/- compared to sex- and aged-matched wt controls. In contrast, isolated slc26a9^-/- islets in short term culture displayed no difference in insulin content, but a significantly reduced glucose-stimulated insulin secretion compared to age- and sex-matched wt islets, suggesting that the impaired glucose tolerance in the absence of Slc26a9 expression these is a pancreatic defect.

CONCLUSIONS

Deletion of Slc26a9 is associated with a reduction in pancreatic fluid secretion and impaired glucose tolerance in female mice. The results underline the importance of Slc26a9 in pancreatic physiology.

[Endoscopic diagnosis, treatment, and follow-up of polyps of the lower gastrointestinal tract]

BACKGROUND

The endoscopic management of polyps of the lower gastrointestinal tract (l-GIT) has emerged in recent years as a result of numerous technological innovations. However, proven expertise and experience are essential.

OBJECTIVES

Presentation of novel and standard techniques and best-practice recommendations for the characterization and resection of l‑GIT polyps.

METHODS

Recent specialist literature and current guidelines.

RESULTS

High-definition endoscopy should be the standard when performing colonoscopy. The (virtual) chromoendoscopy can improve detection and characterization of polyps, but always requires special expertise and experience of the endoscopist in advanced endoscopic imaging. In this regard, computer-aided-diagnosis (CAD) systems have the potential to support endoscopists in the future. Pedunculated polyps should be removed with a hot snare. Small flat polyps can be resected by cold snare or large forceps. Large, non-pedunculated polyps should be treated in an interdisciplinary approach at a referral center with long-standing experience depending on its malignancy potential. After complete resection of small adenoma without high grade dysplasia, surveillance endoscopy is recommended after 5-10 years. Patients with large adenoma or high grade dysplasia should undergo endoscopy after 3 years and patients with multiple adenoma earlier than 3 years. After incomplete or piecemeal resection or insufficient bowel preparation, near-term endoscopy is recommended.

CONCLUSIONS

Adequate characterization and treatment are essential for the appropriate management of l‑GIT polyps.

Anisotropic Spin-Acoustic Resonance in Silicon Carbide at Room Temperature

We report on acoustically driven spin resonances in atomic-scale centers in silicon carbide at room temperature. Specifically, we use a surface acoustic wave cavity to selectively address spin transitions with magnetic quantum number differences of ±1 and ±2 in the absence of external microwave electromagnetic fields. These spin-acoustic resonances reveal a nontrivial dependence on the static magnetic field orientation, which is attributed to the intrinsic symmetry of the acoustic fields combined with the peculiar properties of a half-integer spin system. We develop a microscopic model of the spin-acoustic interaction, which describes our experimental data without fitting parameters. Furthermore, we predict that traveling surface waves lead to a chiral spin-acoustic resonance that changes upon magnetic field inversion. These results establish silicon carbide as a highly promising hybrid platform for on-chip spin-optomechanical quantum control enabling engineered interactions at room temperature.

[Interventional endoscopy in the gastrointestinal tract : Indications and limitations]

The spectrum of endoscopic techniques has been greatly enlarged in recent years. Lesions and also (iatrogenic) complications that required surgical procedures in the past can now often be treated endoscopically. Advances in endoscopic mucosal resection and submucosal dissection also enable the resection of large or laterally spreading polyps in the gastrointestinal tract. Full-thickness resection is also possible by means of specially designed clips. By the creation of a submucosal tunnel submucosal lesions can be completely excised and the muscle fibers of the lower esophageal sphincter can be endoscopically severed in achalasia patients. Endosonography-guided interventions have developed into the standard procedure for complicated pancreatitis and the use of cholangioscopy offers new therapeutic procedures for the bile and pancreatic ducts. In this continuing medical education article interventional endoscopic techniques are presented and critically evaluated.

[Importance of functional diagnostics in gastroenterology]

In this review article important and frequently used investigation methods for gastrointestinal functional diagnostics are presented. Some other rarely used special investigations are also explained. The hydrogen breath test is simple to carry out, ubiquitously available and enables the detection of lactose, fructose and sorbitol malabsorption. Furthermore, by the application of glucose, the test can be carried out when there is a suspicion of abnormal intestinal bacterial colonization and using lactulose for measuring small intestinal transit time. The ¹³C urea breath test is applied for non-invasive determination of Helicobacter pylori infections and assessment of gastrointestinal transit time, liver and exocrine pancreas functions. The secretin cholecystokinin test was the gold standard for the detection of exocrine pancreas insufficiency. However, measurement of pancreatic elastase in stool is less invasive but also less sensitive. Scintigraphy and capsule investigations with pH and temperature probes constitute important methods for determination of gastric emptying, intestinal and colon transit times. For evaluation of constipation panoramic abdominal images are taken after intake of radiologically opaque markers (Hinton test). For the diagnosis of functional esophageal diseases manometry is indispensable. In addition, manometry is only occasionally used for diagnosing a dysfunction of the sphincter of Oddi, due to the danger of inducing pancreatitis. A 24 h pH-metry is applied for the detection of non-erosive gastroesophageal reflux disease and, if necessary, with impedance measurements. Recent investigation procedures, e. g. specific MRI sequences, sonographic determination of gall bladder ejection fraction, analysis of gastric accomodation or real-time lumen imaging, require further evaluation prior to clinical application.

Stepwise diagnosis in covert hepatic encephalopathy: critical flicker frequency and MELD-score as a first-step approach

BACKGROUND

The diagnosis of covert hepatic encephalopathy (CHE) by means of portosystemic encephalopathy syndrome (PSE) test is costly and therefore infrequently performed.

AIM

To determine the ability of critical flicker frequency (CFF) alone or in combination with laboratory findings, as an initial test to pre-select which patients should undergo further testing for the diagnosis of covert hepatic encephalopathy.

METHODS

This single-centre study included all patients with cirrhosis who underwent PSE and CFF in 2011. CHE was defined by abnormal PSE test. Logistic regression analysis was performed to identify predictors of CHE. ROC curves were used to identify cut-offs of these independent predictors.

RESULTS

One hundred and seventeen patients were included. Seventy (60%) had CHE with a higher MELD [16 (IQR 13-21); P = 0.001] and lower CFF [38 Hz (IQR 36-41) P = 0.0011]. On multivariate analyses, CFF [OR 0.83 (95% CI 0.74-0.94)] and MELD [OR 1.13 (95% CI 1.04-1.22)] were identified as independent predictors of CHE. Sensitivity and specificity of a CFF cut-off of 43 Hz was 93.5% and 42.9%, and for a MELD cut-off of 24, it was 97.5% and 32.8% respectively. Most patients with a MELD-Score <24 and a CFF >43 Hz did not have CHE (78%) and with a MELD-Score >24 and CFF <43 Hz most patients had CHE (85%). Therefore, 27% of patients could avoid further testing with a diagnostic accuracy of 81%.

CONCLUSION

The combination of MELD-score and critical flicker frequency may be used as a first diagnostic step to filter patients, in whom further covert hepatic encephalopathy testing could be avoided.