Glycerate from intestinal fructose metabolism induces islet cell damage and glucose intolerance

Dietary fructose, especially in the context of a high-fat western diet, has been linked to type 2 diabetes. Although the effect of fructose on liver metabolism has been extensively studied, a significant portion of the fructose is first metabolized in the small intestine. Here, we report that dietary fat enhances intestinal fructose metabolism, which releases glycerate into the blood. Chronic high systemic glycerate levels induce glucose intolerance by slowly damaging pancreatic islet cells and reducing islet sizes. Our findings provide a link between dietary fructose and diabetes that is modulated by dietary fat.

Near-infrared optical spectroscopy for pancreas shrinkage estimation with multi synchrosqueezing transform and multivariate regression model

In this article, we proposed a method to estimate pancreas shrinkage with pancreas β cell insulin secretion. The β cells in the pancreas secrete insulin and digestive enzymes after food consumption. Conventionally, the pancreas structure estimation is done with magnetic resonance imaging (MRI) and ultrasound imaging techniques. However, the structure of the pancreas changes due to islet cell death. The presence of islet cells is detected through near infrared (NIR) spectroscopy signal acquired from the epigastric region (pancreas) of the abdomen. Subsequently, the NIR spectroscopy signal from the pancreas is analyzed with multi synchrosqueezing transform (MSST); whereas, the β cell insulin secretion varies for diabetic and nondiabetic persons. The existence of β cell and insulin secretion correlates with Root Mean Square (RMS) and kurtosis via a multivariate regression model to evaluate pancreas shrinkage. In terms of numerical results, NIR spectroscopy signal from the pancreas was obtained for about 20 nondiabetic and 20 diabetic persons. The pancreas shrinkage was estimated with 88% accuracy. The results are validated with MRI pancreas images for earlier detection of the apoptotic pancreas. The pancreas shrinkage causes lower insulin emission and unpredictable blood glucose in diabetic patients. Analysis of NIR spectroscopy signals of the pancreas with MSST was done to obtain higher-order and lower-order frequency components.

Differentiation between non-hypervascular pancreatic neuroendocrine tumour and pancreatic ductal adenocarcinoma on dynamic computed tomography and non-enhanced magnetic resonance imaging

Purpose

To determine the differentiating features between non-hypervascular pancreatic neuroendocrine tumour (PNET) and pancreatic ductal adenocarcinoma (PDAC) on dynamic computed tomography (CT) and non-enhanced magnetic resonance imaging (MRI).

Material and methods

We enrolled 102 patients with non-hypervascular PNET (n = 15) or PDAC (n = 87), who had undergone dynamic CT and non-enhanced MRI. One radiologist evaluated all images, and the results were subjected to univariate and multivariate analyses. To investigate reproducibility, a second radiologist re-evaluated features that were significantly different between PNET and PDAC on multivariate analysis.

Results

Tumour margin (well-defined or ill-defined) and enhancement ratio of tumour (ERT) showed significant differences in univariate and multivariate analyses. Multivariate analysis revealed a predominance of well-defined tumour margins in non-hypervascular PNET, with an odds ratio of 168.86 (95% confidence interval [CI]: 10.62-2685.29; p < 0.001). Furthermore, ERT was significantly lower in non-hypervascular PNET than in PDAC, with an odds ratio of 85.80 (95% CI: 2.57-2860.95; p = 0.01). Sensitivity, specificity, and accuracy were 86.7%, 96.6%, and 95.1%, respectively, when the tumour margin was used as the criteria. The values for ERT were 66.7%, 98.9%, and 94.1%, respectively. In reproducibility tests, both tumour margin and ERT showed substantial agreement (margin of tumour, κ = 0.6356; ERT, intraclass correlation coefficients (ICC) = 0.6155).

Conclusions

Non-hypervascular PNET showed well-defined margins and lower ERT compared to PDAC, with significant differences. Our results showed that non-hypervascular PNET can be differentiated from PDAC via dynamic CT and non-enhanced MRI.

Liver Doppler Findings in Pediatric Patients After Total Pancreatectomy and Islet Autotransplantation

OBJECTIVES

This study was intended to establish normal values for velocities in the hepatic artery and portal veins in pediatric patients after total pancreatectomy and islet autotransplantation (TPIAT).

METHODS

A retrospective review was performed of liver Doppler studies in pediatric patients after TPIAT over 6 years at an academic children's hospital. Doppler velocities in the liver vasculature and the hepatic artery resistive index were recorded.

RESULTS

Sixty-five pediatric patients were evaluated. There were no cases of portal vein thrombosis or other hepatic vascular complications. The mean hepatic artery peak systolic velocity was 157.6 cm/s (SE, 60.9 cm/s), with a mean resistive index of 0.57 (SE, 0.09). The mean main portal vein velocity was 31.9 cm/s (SE, 12.9 cm/s).

CONCLUSIONS

Portal vein thrombosis is rare in pediatric patients after TPIAT. A wide range of hepatic artery and portal vein velocities are encountered in children immediately after TPIAT without hepatic vascular complications and can be considered normal.

Targeting mitochondria with folic acid and vitamin B12 ameliorates nicotine mediated islet cell dysfunction

Nicotine, one of the well-known highly toxic components of cigarette smoke, causes a number of adverse health effects and diseases. Our previous study has shown that nicotine induces reactive oxygen species (ROS) in islet cell and disrupts islet cell mitochondrial membrane potential (ΔΨm). However, supplementation with folic acid and vitamin B12 were found effective against nicotine induced changes in pancreatic islet cells. But the toxicological effects and underlying mechanisms of nicotine-induced mitochondrial dysfunction is still unknown. In this study, nicotine exposure decreases mitochondrial enzymes (pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, aconitase, malate dehydrogenase) activities by increasing cytosolic Ca2+ level which may contribute to increased mitochondrial ROS production by raising its flow to mitochondria. This in turn produces malondialdehyde and nitric oxide (NO) with a concomitant decrease in the activities of antioxidative enzymes and glutathione levels leading to loss of ΔΨm. Simultaneously, nicotine induces pancreatic islet cell apoptosis by modulating ΔΨm via increased cytosolic Ca2+ level, altered Bcl-2, Bax, cytochrome c, caspase-9, PARP expressions which were prevented by the supplementation of folic acid and vitamin B12 . In conclusion, nicotine alters islet cell mitochondrial redox status, apoptotic machinery, and enzymes to cause disruption in the ΔΨm and supplementation of folic acid and vitamin B12 possibly blunted all these mitochondrial alterations. Therefore, this study may help to determine the pathophysiology of nicotine-mediated islet cell mitochondrial dysfunction.

Hypothyroidism in utero stimulates pancreatic beta cell proliferation and hyperinsulinaemia in the ovine fetus during late gestation

Key points

Thyroid hormones are important regulators of growth and maturation before birth, although the extent to which their actions are mediated by insulin and the development of pancreatic beta cell mass is unknown.

Hypothyroidism in fetal sheep induced by removal of the thyroid gland caused asymmetric organ growth, increased pancreatic beta cell mass and proliferation, and was associated with increased circulating concentrations of insulin and leptin.

In isolated fetal sheep islets studied in vitro, thyroid hormones inhibited beta cell proliferation in a dose‐dependent manner, while high concentrations of insulin and leptin stimulated proliferation.

The developing pancreatic beta cell is therefore sensitive to thyroid hormone, insulin and leptin before birth, with possible consequences for pancreatic function in fetal and later life.

The findings of this study highlight the importance of thyroid hormones during pregnancy for normal development of the fetal pancreas.

Abstract

Development of pancreatic beta cell mass before birth is essential for normal growth of the fetus and for long‐term control of carbohydrate metabolism in postnatal life. Thyroid hormones are also important regulators of fetal growth, and the present study tested the hypotheses that thyroid hormones promote beta cell proliferation in the fetal ovine pancreatic islets, and that growth retardation in hypothyroid fetal sheep is associated with reductions in pancreatic beta cell mass and circulating insulin concentration in utero. Organ growth and pancreatic islet cell proliferation and mass were examined in sheep fetuses following removal of the thyroid gland in utero. The effects of triiodothyronine (T₃), insulin and leptin on beta cell proliferation rates were determined in isolated fetal ovine pancreatic islets in vitro. Hypothyroidism in the sheep fetus resulted in an asymmetric pattern of organ growth, pancreatic beta cell hyperplasia, and elevated plasma insulin and leptin concentrations. In pancreatic islets isolated from intact fetal sheep, beta cell proliferation in vitro was reduced by T₃ in a dose‐dependent manner and increased by insulin at high concentrations only. Leptin induced a bimodal response whereby beta cell proliferation was suppressed at the lowest, and increased at the highest, concentrations. Therefore, proliferation of beta cells isolated from the ovine fetal pancreas is sensitive to physiological concentrations of T₃, insulin and leptin. Alterations in these hormones may be responsible for the increased beta cell proliferation and mass observed in the hypothyroid sheep fetus and may have consequences for pancreatic function in later life.

Thyroid hormones are important regulators of growth and maturation before birth, although the extent to which their actions are mediated by insulin and the development of pancreatic beta cell mass is unknown.

Hypothyroidism in fetal sheep induced by removal of the thyroid gland caused asymmetric organ growth, increased pancreatic beta cell mass and proliferation, and was associated with increased circulating concentrations of insulin and leptin.

In isolated fetal sheep islets studied in vitro, thyroid hormones inhibited beta cell proliferation in a dose‐dependent manner, while high concentrations of insulin and leptin stimulated proliferation.

The developing pancreatic beta cell is therefore sensitive to thyroid hormone, insulin and leptin before birth, with possible consequences for pancreatic function in fetal and later life.

The findings of this study highlight the importance of thyroid hormones during pregnancy for normal development of the fetal pancreas.

Protective efficacy of folic acid and vitamin B12 against nicotine-induced toxicity in pancreatic islets of the rat

Although cigarette smoking is associated with insulin resistance and an increased risk for type 2 diabetes, few studies have examined the effect of nicotine on the adult endocrine pancreas. In this study, male Wister rats were treated with nicotine (3 mg/kg body weight/ day) with or without supplementation of folic acid (36 μg/kg body weight/day) or vitamin B12 (0.63 μg/kg body weight/day) alone or in combination. Fasting blood glucose, insulin and HBA1C level and different oxidative and anti-oxidative stress parameters were measured and pancreatic tissue sections were stained with eosin-haematoxylene. Data were analysed by nonparametric statistics. The results revealed that nicotine induced prediabetes condition with subsequent damage to pancreatic islets in rats. Nicotine also caused oxidative stress in pancreatic tissue as evidenced by increased nitric oxide and malondialdehyde level and decreased superoxide dismutase, catalase and reduced glutathione level. Compared to vitamin B12 supplementation, folic acid blunted the nicotine-induced toxicity in pancreatic islets with higher efficacy. Further, folic acid and vitamin B12 in combination were able to confer significant protection on pancreatic islets against nicotine induced toxicity. These results suggest that supplementation of folic acid and vitamin B12 in combination may be a possible strategy of detoxification against nicotine-induced toxicity in pancreatic islets of the rat.

Fatal hepatitis B reactivation in a patient with islet cell tumor on octreotide and sirolimus

Reactivation of hepatitis B viral infection (HBVr) is a known risk in cancer patients with a history of chronic hepatitis B infection receiving cytotoxic or immunosuppressive therapies. Patients with hematologic malignancies or those who have received stem cell transplantation seem to be most at risk but reactivation has been reported with various malignancies. Reactivation can present as asymptomatic liver function test abnormalities (LFTs), with symptoms of abdominal pain, encephalopathy, or as fulminant hepatitis and liver failure. Here we report the first case of a patient with islet cell tumor on octreotide and sirolimus who developed hepatitis B reactivation with fulminant liver failure and death.

Characterization of β-cell function and insulin resistance in overweight Chinese adolescents with normal glucose tolerance

This study aimed to investigate the characteristics of insulin resistance and β-cell secretion in healthy adolescents. A total of 124 adolescents with normal glucose tolerance (NGT) were divided according to BMI into normal weight (n=31; control), overweight (n=52) and obese (n=41) groups. Oral glucose tolerance tests were performed, and blood glucose (G₀, G₃₀ and G₁₂₀) and insulin (I₀, I₃₀ and I₁₂₀) levels at 0, 30 and 120 min, respectively, were measured. The homeostasis model assessment estimate of insulin resistance (HOMA-IR) and early insulin release index (IRI) were calculated to evaluate insulin sensitivity and early β-cell secretion. The G₀, G₁₂₀ levels and the natural logarithm (Ln) of I₃₀ and ΔI₃₀/ΔG₃₀ were similar in the overweight and obese groups, but significantly higher compared with those of the normal weight group (P<0.05). LnI₀ and LnHOMA-IR progressively increased (P<0.01) in correlation with the degree of obesity among the three groups. LnΔI₃₀/ΔG₃₀ and LnHOMA-IR were significantly positively correlated with the indices of obesity (P<0.001 and P<0.05, respectively). LnHOMA-IR was also positively correlated with the insulin levels at 30 and 120 min (r=0.454 and 0.314, respectively; P<0.001). In healthy adolescents, insulin resistance progressively increased with increased body mass index (BMI), but the compensatory increase in early insulin secretion was limited.

Microcapsules with intrinsic barium radiopacity for immunoprotection and X-ray/CT imaging of pancreatic islet cells

Microencapsulation is a commonly used technique for immunoprotection of engrafted therapeutic cells. We investigated a library of capsule formulations to determine the most optimal formulation for pancreatic beta islet cell transplantation, using barium as the gelating ion and clinical-grade protamine sulfate (PS) as a new cationic capsule cross-linker. Barium-gelated alginate/PS/alginate microcapsules (APSA, diameter = 444 ± 21 μm) proved to be mechanically stronger and supported a higher cell viability as compared to conventional alginate/poly-l-lysine/alginate (APLLA) capsules. Human pancreatic islets encapsulated inside APSA capsules, gelated with 20 mm barium as optimal concentration, exhibited a sustained morphological integrity, viability, and functionality for at least 3-4 weeks in vitro, with secreted human C-peptide levels of 0.2-160 pg/ml/islet. Unlike APLLA capsules that are gelled with calcium, barium-APSA capsules are intrinsically radiopaque and, when engrafted into mice, could be readily imaged in vivo with micro-computed tomography (CT). Without the need of adding contrast agents, these capsules offer a clinically applicable alternative for simultaneous immunoprotection and real-time, non-invasive X-ray/CT monitoring of engrafted cells during and after in vivo administration.

NANETS treatment guidelines: well-differentiated neuroendocrine tumors of the stomach and pancreas

Well-differentiated neuroendocrine tumors (NETs) of the stomach and pancreas represent 2 major subtypes of gastrointestinal NETs. Historically, there has been little consensus on the classification and management of patients with these tumor subtypes. We provide an overview of well-differentiated NETs of the stomach and pancreas and describe consensus guidelines for the treatment of patients with these malignancies.

Gastroenteropancreatic neuroendocrine tumors in children and young adults

We review the imaging findings of pediatric gastroenteropancreatic neuroendocrine tumors (GEP-NETs) using contemporary anatomic and molecular imaging techniques. A low index of suspicion can result in significant delays in diagnosis of pediatric GEP-NETs. A multimodality imaging approach, using both anatomic and functional imaging, is essential in the diagnosis, staging, and surveillance of these potentially malignant tumors.

A large malignant insulinoma: case report with endosonographic, immunohistochemical and ultrastructural features

Malignant insulinoma in the beta cells of the pancreatic islet is rare and usually presented as hypoglycemia. We report a case of large malignant insulinoma in a 53-year-old Korean woman. A presumptive clinical diagnosis was made before surgery, based on the high plasma insulin-to-glucose ratio and a large solitary heterogeneous pancreatic mass by abdominal computed tomography and endosonography. The tumor measured 5.8 x 4.7 x 4.5 cm in dimension and showed capsular invasions and metastases in two of four peripancreatic lymph nodes. The tumor cells were strongly immunoreactive to insulin and had a high Ki-67 labeling index (13%) and atypical membranous electron-dense granules, ranging from 120 to 400 nm in diameter, in the cytoplasm on electron microscopy. The patient was treated by distal pancreatectomy with splenectomy and rapidly recovered without neurohypoglycemic symptoms. This case showed not only lymph node metastases, the most reliable parameter for malignancy in pancreatic endocrine tumors, but also other valid diagnostic clues, such as high Ki-67 labeling index, heterogeneous enodosonographic findings, capsular invasions with large tumor and pure atypical secretory granules.