Glucose-incretin interaction revisited

Pancreatic beta cell dysfunction is pivotal to the development of diabetes, and restoration of insulin action is of primary importance. Here, we present a review of the mechanism of insulin secretion by pancreatic beta cells and discuss the mutual interaction of signaling pathways in stimulus-secretion coupling to better understand the scientific basis of pharmacological treatment for insulin secretion deficiency. Glucose stimulates insulin secretion via membrane depolarization by closure of ATP-sensitive K(+) channels (K(ATP) channels) and opening of L-type voltage-dependent Ca(2+) channels. The resultant elevation of cytosolic free Ca(2+) triggers insulin exocytosis. This is termed the "K(ATP)-dependent pathway" and is shared by sulfonylurea, which closes K(ATP) channels. Glucose also stimulates insulin release independent of its action on K(ATP) channels. This is referred to as the "K(ATP)-independent pathway," the molecular basis of which remains elusive. In the pancreatic beta cell, incretin hormones increase cAMP level, which enhances glucose-stimulated insulin release by protein kinase A-dependent and -independent mechanisms. Importantly, cAMP does not directly augment Ca(2+)-stimulated insulin release per se. The stimulatory level of ambient glucose is an absolute requirement for incretin to enhance insulin release. Therefore, incretin/cAMP enhances K(ATP)-independent insulinotropic action of glucose. The robust glucose-lowering effect of DPP4 inhibitor add-on in diabetic patients with sulfonylurea secondary failure is intriguing. With the clinical availability of DPP4 inhibitor and GLP-1 mimetics, the importance of the interactions between cAMP signaling and K(ATP) channel-independent actions of glucose is reappraised.     

Monitoring transplanted islets by high-frequency ultrasound

Islet transplantation is a cell replacement therapy to improve glycometabolic control in type 1 diabetic patients. Establishing methods to monitor engrafted islets, as well as the islet preparation, is important when performing islet transplantation. Since current imaging techniques are still not available to directly detect transplanted islets, we propose a novel method to visualize transplanted islets using high-frequency ultrasound (HF-US), and to evaluate the correlation between these US findings and metabolic parameters. We transplanted syngeneic (BALB/c mice) and xenogeneic (SD rats) islets into the renal subcapsular space of diabetic mice. The recipient mice were examined by HF-US until post-operative day (POD) 28 and, while syngeneic islets could be detected by HF-US throughout the observational period, the xenogeneic islets had vanished by POD 28. The islet volume calculated by HF-US was correlated with the number of transplanted islets (R(2) = 0.31, p = 0.0003) and the metabolic function of islets (blood glucose: R(2) = 0.15, p < 0.0001, serum insulin: R(2) = 0.22, p < 0.0001). In conclusion, HF-US may be a useful imaging modality for visualizing the islet mass in renal subcapsular transplantation models. It may also be an available modality for clinical settings in the future.     

Association of low serum adiponectin levels with erosive esophagitis in men: an analysis of 2405 subjects undergoing physical check-ups

Background

Obesity is a risk factor for gastro-esophageal reflux disease (GERD). It is generally considered that intra-abdominal pressure in obese subjects is involved in the pathogenesis of GERD through acid exposure to the esophagus. Recently, visceral fat has been recognized as an endocrine organ that secretes various adipocytokines including adiponectin. The aim of this study was to elucidate the relation between adiponectin and erosive esophagitis.

Methods

This was a cross-sectional retrospective observational study: 2405 consecutive subjects who underwent screening esophago-gastro-duodenoscopy with serum adiponectin measurement as part of their physical check-up programs were analyzed. Clinical factors were compared between subjects with and without erosive esophagitis. The association between adiponectin and erosive esophagitis was assessed using a bootstrapping re-sampling method after adjustment for factors that tended to be different in univariate analysis.

Results

Serum adiponectin levels were significantly lower in those with erosive esophagitis (8.17???g/ml) than in those without (10.1). The erosive esophagitis group had a greater body mass index (BMI) and waist circumference (WC) and a higher prevalence of hiatal hernia. Using the bootstrap method, with a lower adiponectin cut-off value of 3?C7???g/ml, the lower limit of the 95% confidence interval of the adjusted odds ratio consistently exceeded 1 after adjustment for BMI and hiatal hernia in men. When adjusting for WC instead of BMI, the effect of adiponectin was reduced but remained significant at a lower cut-off value (3?C3.5???g/ml).

Conclusions

Low serum adiponectin levels may be associated with an increased risk for erosive esophagitis in men.     

Esophageal granular cell tumor successfully resected by endoscopic submucosal dissection

Granular cell tumors of the esophagus are rare neoplasms and their diagnosis is mainly based on histopathologic examination of endoscopic biopsies. With the development of endoscopic techniques, there has been a marked increase in local treatment modalities for early esophageal neoplasms. In this case report, we describe the removal of a granular cell tumor by the endoscopic submucosal dissection technique, and briefly discuss the literature on clinicopathologic aspects and management of granular cell tumors.     

Primary hepatic actinomycosis concomitant with elevation of protein induced by vitamin K absence or antagonist II - report of a case

We report a case of primary hepatic actinomycosis showing elevation of serum protein induced by vitamin K absence or antagonist II (PIVKA-II). A 68-year-old man visited an affiliated hospital with a complaint of high fever and body weight loss. Hematological examination revealed severe inflammatory reactions and liver dysfunction. Abdominal CT showed a heterogeneous low density area composed of cystic and solid part. We suspected the cystic part with band-like enhancement to be a hepatic abscess and performed percutaneous transhepatic abscess drainage. Although inflammatory reactions decreased after the drainage, the solid part did not shrink and blood chemistry revealed elevation of PIVKA-II. Since we could not rule out the possibility of hepatoma, right hepatectomy was performed. Histological examination revealed actinomycetes. Although primary hepatic actinomycosis is a rare disease, it must be kept in mind in the differential diagnosis of the liver tumor.     

Comparison between the <Superscript>13</Superscript>C-urea breath test and stool antigen test for the diagnosis of childhood <Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection

Background As noninvasive tests for Helicobacter pylori infection, the ¹³C-urea breath test (UBT) and stool antigen test have been widely used. In children, however, there are few studies reporting which test shows superior performance. The purpose of this study was to compare the ¹³C-UBT and stool antigen test for their accuracy in diagnosing H. pylori infection in children.Methods A total of 123 Japanese children, ages 2 to 17 years (mean, 12 years) who underwent gastric biopsies for H. pylori infection were studied. The diagnoses included gastritis (n = 55), gastric ulcer (n = 5), duodenal ulcer (n = 20), iron-deficiency anemia (n = 7), and other conditions (n = 36). The cutoff value of the ¹³C-UBT was defined to be 3.5. The stool antigen test was performed using the HpSA enzyme-linked immunosorbent assay (ELISA) (Premier Platinum HpSA). In 16 patients who received eradication therapy, the ¹³C-UBT and HpSA were repeated 2 months after treatment.Results Based on biopsy tests, 60 children were infected with H. pylori and 63 children were not. For the ¹³C-UBT, the sensitivity, specificity, and accuracy were 95.0% (95% confidence interval [CI], 86.1%–99.0%), 98.4% (95% CI, 91.5%–100%), and 96.4% (95% CI, 93.6%–99.9%), respectively. For the HpSA, the sensitivity, specificity, and accuracy were 98.3% (95% CI, 90.8%–100%), 98.4% (95% CI, 91.2%–100%), and 98.3% (95% CI, 96.0%–100%), respectively. There were no significant differences between the performance of these two tests. In the assessment of H. pylori eradication, the results of ¹³C-UBT and HpSA agreed with those of biopsy tests.Conclusions The ¹³C-UBT and the HpSA are equally accurate for the diagnosis of active H. pylori infection in Japanese children.Kazuie Iinuma, for the Japanese Pediatric Helicobacter study Group     

Rectal cancer associated with chronic lymphocytic leukemia

It has been reported that chronic lymphocytic leukemia (CLL) often occurs concomitantly with other malignant neoplasms. However, because CLL is rare in Japan, there are only a limited number of reports of the occurrence of malignant neoplasia in Japanese patients with CLL. We report here the simultaneous occurrence of rectal cancer and CLL in a 57-year-old man. Because the clinical stage of CLL was Rai system I, we decided, in accordance with the National Cancer Institute–Sponsored Working Group guidelines, to monitor him without therapy for CLL until evidence of disease progression, and we performed abdominoperineal resection of the rectum for the cancer. The small rectal tumor was associated with aggressive lymphangiosis carcinomatosa, and multiple nodal metastases were observed in the pool of CLL cells. He died of rectal cancer 7 months after the operation, and autopsy revealed extensive metastases of the cancer. Cellular and humoral immunity is often impaired in patients with CLL, and the defective immunity in this patient may have had an etiological role in the development and rapid progression of the cancer. In the follow-up of CLL patients, we must always be aware of the possible existence of a second malignant disease. Particular attention should be paid to those with defective immunity, and screening should be performed, especially for pulmonary and gastrointestinal malignancies.     

Functional status and active life expectancy among senior citizens in a small town in Japan

The objectives of this study were to understand transition patterns and mechanisms of functional status, and to estimate active life expectancy (ALE) among senior citizens in a small town in Japan. With data drawn from surveys conducted annually from 1998 to 2002 (n=638 at baseline), prevalence and incidence of functional disability in activities of daily living (ADL) and instrumental activities of daily living (IADL) were described and compared between the sexes. Then relationships between potential predictors and functional decline through a 4-year follow-up were examined using logistic regression. Finally, active and disabled life expectancy was estimated by Katz's method. At baseline, 9 and 12% of subjects were dependent in performing ADL and IADL, respectively. Prevalence and incidence rates increased with age. The risk of mortality increased by 2.2-5.0-fold when the subject was functionally dependent at the previous year. Advanced age, difficulty in walking and poor interest were shown to be significant predictors of loss of independence in ADL. Mean durations with disability in ADL and IADL among women were longer than among men by around 1 year. Population-specific preventive care programs considering physical, cognitive and social aspects are needed not only to maximize ALE but also to improve quality of life during survival period with disability especially in old women.     

Assessment of regional wall motion using strain Doppler imaging during right ventricular bifocal pacing in a patient with severe congestive heart failure: a case report

A 79-year-old man presented with dilated cardiomyopathy and chronic atrial fibrillation. A DDD pacemaker was implanted due to sick sinus syndrome. His left ventricular ejection fraction was 23%. He was repeatedly admitted with congestive heart failure. Although cardiac resynchronization therapy was attempted, insertion of a pacing lead into the coronary sinus failed. Right ventricular bifocal pacing was done. The QRS width was shortened to 155 msec during bifocal pacing and 157 msec during right ventricular outflow pacing from 221 msec during right ventricular apical pacing. Heart failure was improved from New York Heart Association class III to II. Regional wall motion was assessed by strain of the myocardium. Bifocal pacing increased stroke volume due to improvement of longitudinal dyssynchrony of the septal and lateral walls. Bifocal pacing is effective for patients with severe congestive heart failure in whom biventricular pacing therapy has failed. Strain Doppler imaging is useful for the assessment of regional wall motion during cardiac pacing.     

Distinct effects of pravastatin, atorvastatin, and simvastatin on insulin secretion from a beta-cell line, MIN6 cells

In addition to the prevention of cardiovascular diseases by lowering plasma LDL cholesterol, recent studies suggest that statins could have some impact on insulin action. To estimate the direct effects of statins on insulin secretion from pancreatic beta-cells, MIN6 cells were treated with pravastatin, simvastatin, or atorvastatin. Basal insulin secretion at low glucose concentration was unexpectedly increased at very high doses of simvastatin or atorvastatin after 24- and 48-hour incubation. Insulin secretion at high glucose was not significantly changed, and thus, net glucose-stimulated insulin secretion was apparently decreased by these lipophilic statins. The changes in insulin secretion were highly associated with increased endogenous SREBP activities in response to HMG-CoA inhibition as estimated by SRE-luciferase assays, and finally after 48-hour incubation, accompanied by impaired cell viability as estimated by MTT assays. In contrast, these changes were much less prominent by the addition of pravastatin. Meanwhile, glucose-stimulated insulin secretion of islets isolated from C57BL/6 mice was not significantly changed by any of the statins. Overall, taken up by beta-cells, statins can affect insulin secretion through either HMG-CoA inhibition or cytotoxicity, as observed by the addition of extraordinary high doses of lipophilic statins, but not hydrophilic statins, to the medium.