Pancreatic Polypeptide Research Articles

Antimicrobial Peptides: A New Hope in Biomedical and Pharmaceutical Fields.

Antibiotics are essential drugs used to treat pathogenic bacteria, but their prolonged use contributes to the development and spread of drug-resistant microorganisms. Antibiotic resistance is a serious challenge and has led to the need for new alternative molecules less prone to bacterial resistance. Antimicrobial peptides (AMPs) have aroused great interest as potential next-generation antibiotics, since they are bioactive small proteins, naturally produced by all living organisms, and representing the first line of defense against fungi, viruses and bacteria. AMPs are commonly classified according to their sources, which are represented by microorganisms, plants and animals, as well as to their secondary structure, their biosynthesis and their mechanism of action. They find application in different fields such as agriculture, food industry and medicine, on which we focused our attention in this review. Particularly, we examined AMP potential applicability in wound healing, skin infections and metabolic syndrome, considering their ability to act as potential Angiotensin-Converting Enzyme I and pancreatic lipase inhibitory peptides as well as antioxidant peptides. Moreover, we argued about the pharmacokinetic and pharmacodynamic approaches to develop new antibiotics, the drug development strategies and the formulation approaches which need to be taken into account in developing clinically suitable AMP applications.

The Enigmatic N-Terminal Domain of Proglucagon; A Historical Perspective.

Enteroglucagon refers to the predominant peptide with glucagon-like immunoreactivity (GLI) that is released by the intestine into the circulation in response to nutrients. Development of a radioimmunoassay for glucagon revealed issues that were not apparent in applications of the insulin radioimmunoassay. The fact that some antisera raised against glucagon recognized glucagon-related peptides in extracts of both pancreas and gut whereas others recognized only components in the pancreas remained a mystery until it was realized that the “gut GLI cross-reactive” antisera were directed against an epitope in the N-terminal to central region of glucagon whereas the “pancreatic glucagon specific” antisera were directed against an epitope in the C-terminal region. Unlike the cross-reactive antisera, the glucagon specific antisera did not recognize components in which glucagon was extended from its C-terminus by additional amino acids. Initial attempts to purify enteroglucagon from porcine ileum led to the erroneous conclusion that enteroglucagon comprised 100 amino acids with an apparent molecular mass of 12,000 Da and was consequently given the name glicentin. Subsequent work established that the peptide constituted residues (1-69) of proglucagon (Mr 8128). In the 40 years since the structural characterization of glicentin, attempts to establish an unambiguous physiological function for enteroglucagon have not been successful. Unlike the oxyntomodulin domain at the C-terminus of enteroglucagon, the primary structure of the N-terminal domain (glicentin-related pancreatic peptide) has been poorly conserved among mammals. Consequently, most investigations of the bioactivity of porcine glicentin may have been carried out in inappropriate animal models. Enteroglucagon may simply represent an inactive peptide that ensures that the intestine does not release equimolar amounts of a hyperglycemic agent (glucagon) and a hypoglycemic agent (GLP-1) after ingestion of nutrients.

The Roles of Neuropeptide Y (Npy) and Peptide YY (Pyy) in Teleost Food Intake: A Mini Review.

Neuropeptide Y family (NPY) is a potent orexigenic peptide and pancreatic polypeptide family comprising neuropeptide Y (Npy), peptide YYa (Pyya), and peptide YYb (Pyyb), which was previously known as peptide Y (PY), and tetrapod pancreatic polypeptide (PP), but has not been exhaustively documented in fish. Nonetheless, Npy and Pyy to date have been the key focus of countless research studies categorizing their copious characteristics in the body, which, among other things, include the mechanism of feeding behavior, cortical neural activity, heart activity, and the regulation of emotions in teleost. In this review, we focused on the role of neuropeptide Y gene (Npy) and peptide YY gene (Pyy) in teleost food intake. Feeding is essential in fish to ensure growth and perpetuation, being indispensable in the aquaculture settings where growth is prioritized. Therefore, a better understanding of the roles of these genes in food intake in teleost could help determine their feeding regime, regulation, growth, and development, which will possibly be fundamental in fish culture.

Pancreatic and gut hormones as predictors of new-onset prediabetes after non-necrotising acute pancreatitis: a prospective longitudinal cohort study.

ObjectiveEarly identification of individuals at high risk for metabolic derangements after an attack of acute pancreatitis (AP) is critical with a view to tertiary preventing of this disease. The aim was to investigate whether fasting pancreatic and gut hormones at baseline were predictive of future risk of new-onset prediabetes after acute pancreatitis (NOPAP) in individuals with non-necrotising AP.MethodsThis was a prospective longitudinal cohort study that included 69 consecutive non-diabetic participants with AP, of whom 55% (n = 38) had normoglycaemia both at baseline and during follow-up, 25% (n = 17) had prediabetes both at baseline and during follow-up, and 20% (n = 14) were normoglycaemic at baseline but developed NOPAP during follow-up. The associations between the study groups and circulating fasting levels of pancreatic and gut hormones (insulin, glucagon, C-peptide, amylin, glucose-dependent insulinotropic peptide, glucagon-like peptide-1, pancreatic polypeptide, and peptide YY) were studied using multinomial regression in both unadjusted and adjusted analyses.ResultsElevated plasma insulin and glucagon at baseline were significantly associated with NOPAP (adjusted odds ratio 1.99, 95% CI 1.01 to 3.92 and adjusted odds ratio 3.44, 95% CI 1.06 to 11.19, respectively). The same hormones had no significant association with antecedent prediabetes in AP. The other studied hormones were not significantly associated with the study groups.ConclusionsNormoglycaemic AP individuals with elevated fasting levels of insulin and glucagon at baseline constitute a high-risk group for future NOPAP.

224-LB: A Study to Evaluate the Glucagon and Incretin Responses and Identify the Role of Extrapancreatic Glucagon in Patients with Fibrocalcific Pancreatic Diabetes

Aim: The aim of this study is to evaluate glucagon and incretin responses in patients with FCPD. Methods: Nine FCPD patients and six age- and body mass index-matched healthy controls were subjected to 75 g oral glucose tolerance test (OGTT) followed by isoglycemic intravenous glucose infusion (IIGI). Blood samples were analyzed for incretins and glucagon at nine pre-specified time-points over 3 h and the area under curve was calculated. Results: Glucagon was significantly higher during OGTT compared to IIGI in FCPD patients (98.8 ± 13 pg/ml vs. 63.4 ± 7 pg/ml, P = 0.03) and was also higher when compared to controls (98.8 ± 13 pg/ ml vs. 65.8 ± 18 pg/ml, P = ns). FCPD patients showed very low basal and stimulated c-peptide (0.43 ± 0.14 ng/ml and 1.09 ± 0.3 ng/ ml, respectively) and pancreatic polypeptide (12.3 ± 0.0pg/ml and 12.0 ± 0.6 pg/ml, respectively) levels. Glucagon-like peptide-1 (GLP-1) was significantly higher in cases on OGTT when compared to controls (44.5 ± 9.2 pM vs. 12.8 ± 7.5 pM, P = 0.02). Oxyntomodulin was also insignificantly higher in cases on OGTT when compared to controls (1252 ± 350 pg/ml vs. 859.8 ± 165 pg/ml, P = 0.43). GIP was lower in cases on IIGI when compared to controls (52.9 ± 23.9 pg/ml vs. 144.5 ± 36.1 pg/ml, P = 0.045) and there was blunted response on OGTT as well (106.8 ± 40.3 pg/ml vs. 557.8 ± 96.4 pg/ml, P = 0.003). Discussion: We found hyperglucagonemia in FCPD on OGTT, which was suppressed on IIGI. Increase in L-cell products: GLP-1 and oxyntomodulin and a good correlation between glucagon and GLP-1 during OGTT were suggestive of extrapancreatic glucagon production probably from L-cell. The blunted GIP could probably be due to: inadequate pancreatic enzyme supplements, a selective PC-2 enzyme up-regulation or a negative feedback regulation from extrapancreatic glucagon. Conclusion: Extrapancreatic glucagon does exist in FCPD and may contribute to postprandial hyperglycemia and lower GIP levels. Disclosure A. Shankar: None.

Middle Ear "Adenoma": a Neuroendocrine Tumor with Predominant L Cell Differentiation.

This morphological and immunohistochemical study demonstrates that tumors currently known as "middle ear adenomas" are truly well-differentiated epithelial neuroendocrine tumors (NETs) composed of cells comparable to normal intestinal L cells, and therefore, these tumors resemble hindgut NETs. These tumors show consistent expression of glucagon, pancreatic polypeptide, PYY, and the transcription factor SATB2, as well as generic neuroendocrine markers and keratins. The same L cell markers are expressed by cells within the normal middle ear epithelium. These markers define a valuable immunohistochemical profile that can be used for differential diagnosis of middle ear neoplasms, particularly in distinguishing epithelial NETs from paragangliomas. The discovery of neuroendocrine cells expressing the same markers in non-neoplastic middle ear mucosa opens new areas of investigation into the physiology of the normal middle ear and the pathophysiology of middle ear disorders.

Multifocal pancreatic PPoma in the setting of MEN1: Case report and review of literature.

Introduction and importanceFunctioning pancreatic neuroendocrine tumors (pNETs) that express pancreatic polypeptide—PPomas—do not yet have a pathognomonic clinical syndrome associated with them due to their overall rarity and diverse symptoms. Moreover, in patients with MEN1, the often multifocal nature of pNETs presents a unique clinical issue.Case presentationWe report a case of a 22-year-old man with a known MEN1 gene mutation who was suffering from severe diarrhea (7–8 bowel movements per day) and was found to have only elevated PP levels on biochemical work-up. Ga68-DOTATATE PET/CT showed multifocal tumors in the body and tail of the pancreas that were not evident on contrast-enhanced CT. The patient underwent a successful laparoscopic radical antegrade modular pancreatosplenectomy (RAMP) and recovered well post-operatively with complete resolution of his diarrhea. Immunohistochemistry showed multiple pure PPomas.Clinical discussionThis case highlights the unique propensity for multifocal disease in patients with MEN1 mutations and the utility of functional imaging by somatostatin analogs, i.e., Ga68-DOTATATE PET/CT, in order to perform oncologic laparoscopic pancreatic resections.ConclusionPPomas in the setting of MEN1 mutations are a unique clinical entity due to their diverse associated clinical syndromes and propensity for multifocal disease.

Pancreatic hormones response-generated machine learning model to help distinguish sporadic pancreatic cancer from new-onset diabetes cohort.

e16235 Background: Diabetes mellitus (DM), a paraneoplastic phenomenon, can develop earlier than other symptoms in pancreatic cancer (PaC) patients. Enhanced surveillance is encouraged on all elderly patients with new-onset DM. However, it is a challenge to differentiate newly developed PaCDM from type 2 DM (T2DM). Thus, we investigated the differences of pancreatic hormones responses and functions between PaCDM and T2DM patients, and developed discriminative model by machine learning algorithms. Methods: PaC patients with normal blood glucose (PaCNG) or with new-onset DM (PaCDM) were recruited. For each case, age and gender matched newly developed T2DM patients and healthy volunteers were selected as controls. After ≥10 hours fasting, all participants underwent a mixed meal stimulation test (MMTT). Blood samples were collected at 0, 15, 30, 60 and 120 min to measure insulin, C-peptide, glucagon, and pancreatic polypeptide (PP). Indices of insulin sensitivity (HOMA-IS, HOMA-IR) and insulin secretion (HOMA-β, insulinogenic index 30’ and 120’) were calculated. Increases in hormone levels were compared among groups with repeated measure analysis. Four machine learning algorithms (Random Forest, Logistic Regression, Support Vector Machines, Naïve bayes) were used to develop quadri-separated discriminative models of PaCDM based on baseline characteristics, pancreatic hormones and insulin indices listed above. Results: Insulin and C-peptide responses to MMTT were blunted in PaCDM patients compared to T2DM. The AUC of insulin were comparatively lower in PaCDM; between-group differences were observed at the fasting (197.15 ± 16.59 pg/mL to 537.96 ± 118.69 pg/mL; P = 0.040) and 15 min (523.94 ± 81.15 pg/mL to 1182.51 ± 219.35 pg/mL; P = 0.036) time-points. No statistical differences among groups were found for glucagon. The mean peak PP concentration after MMTT in PaCDM group (466.67 ± 79.05 pg/mL) was higher than control group (258.54 ± 31.36 pg/mL, P = 0.034), but not statistically different to T2DM patients (452.34 ± 62.96 pg/mL, P = 0.892). PaCDM patients had lower insulin secretion capacity but better insulin sensitivity compared to T2DM patients. Eight indices (age, HbA1c, CA19-9, peak concentration of glucose, area above basal of PP, HOMA-IR, HOMA-IS, HOMA-β) were recruited for model development. And the discriminative model generated by random forest algorithm obtained best performance (AUC = 1.000, CA = 0.963, F-1 = 0.941, Precision = 0.889, Recall = 1.000, Specificity = 0.947; model verified). Conclusions: PaCDM patients tend to present with lower β-cell function and better insulin resistance compared to T2DM patients. As our model based on machine learning algorithm generates a good result for discrimination, the above findings may help with early screening for sporadic PaC in new-onset DM. Clinical trial information: ChiCTR1800018247.

Elucidating Gold-MnO2 Core-Shell Nanoenvelope for Real Time SERS-Guided Photothermal Therapy on Pancreatic Cancer Cells.

Pancreatic cancer represents one of the most aggressive in nature with a miserable prognosis that warrants efficient diagnostic and therapeutic interventions. Herein, a MnO2 overlaid gold nanoparticle (AuNPs) based photothermal theranostic nanoenvelope (PTTNe:MnO2@AuNPs) was fabricated to substantiate surface-enhanced Raman spectroscopy (SERS) guided real-time monitoring of photothermal therapy (PTT) in pancreatic cancer cells. A sharp enhancement of the fingerprint Raman signature of MnO2 at 569 cm-1 exhibited as a marker peak for the first time to elucidate the intracellular PTT event. In this strategic design, the leftover bare AuNPs after the degradation of the MnO2 layer from the nanoenvelope in the presence of intracellular H2O2 enabled real-time tracking of biomolecular changes of Raman spectral variations during PTT. Moreover, the surface of the as-synthesized nanoenvelope was functionalized with a pancreatic cancer cell targeting peptide sequence for cholecystokinin fashioned the PTTNe with admirable stability and biocompatibility. Finally, the precise cell death mechanism was explicitly assessed by SERS spectral analysis as a complementary technique. This targeted phototheranostic approach demonstrated in pancreatic cancer cells presented a therapeutically viable prototype for futuristic personalized cancer nanomedicine.

Proglucagon-Derived Peptides as Therapeutics.

Initially discovered as an impurity in insulin preparations, our understanding of the hyperglycaemic hormone glucagon has evolved markedly over subsequent decades. With description of the precursor proglucagon, we now appreciate that glucagon was just the first proglucagon-derived peptide (PGDP) to be characterised. Other bioactive members of the PGDP family include glucagon-like peptides -1 and -2 (GLP-1 and GLP-2), oxyntomodulin (OXM), glicentin and glicentin-related pancreatic peptide (GRPP), with these being produced via tissue-specific processing of proglucagon by the prohormone convertase (PC) enzymes, PC1/3 and PC2. PGDP peptides exert unique physiological effects that influence metabolism and energy regulation, which has witnessed several of them exploited in the form of long-acting, enzymatically resistant analogues for treatment of various pathologies. As such, intramuscular glucagon is well established in rescue of hypoglycaemia, while GLP-2 analogues are indicated in the management of short bowel syndrome. Furthermore, since approval of the first GLP-1 mimetic for the management of Type 2 diabetes mellitus (T2DM) in 2005, GLP-1 therapeutics have become a mainstay of T2DM management due to multifaceted and sustainable improvements in glycaemia, appetite control and weight loss. More recently, longer-acting PGDP therapeutics have been developed, while newfound benefits on cardioprotection, bone health, renal and liver function and cognition have been uncovered. In the present article, we discuss the physiology of PGDP peptides and their therapeutic applications, with a focus on successful design of analogues including dual and triple PGDP receptor agonists currently in clinical development.

Auricular vagal nerve stimulation enhances gastrointestinal motility and improves interstitial cells of Cajal in rats treated with loperamide.

Gastrointestinal (GI) motility disorders affect a large proportion of the population with limited treatment options. The aims of this study were to investigate the potential of a non-invasive method of auricular vagal nerve stimulation (aVNS) for treating GI dysmotility and to explore possible mechanisms involving slow waves and interstitial cells of Cajal (ICC). Normal rats were treated daily with loperamide for 1 week and then treated, while still on daily loperamide, with aVNS/Sham-aVNS for another 1week. Gastric emptying (GE), small intestine transit (SIT), and GI slow waves were measured. The plasma level of pancreatic polypeptide (PP) and noradrenaline (NE) was assessed by ELISA. ICC in the gastric antrum were detected by immunohistochemistry. (a) aVNS significantly increased the percentage of normal GI slow waves (p<0.05 for both fasting and postprandial states, vs. Sham-aVNS) and accelerated GE (p<0.05, vs. Sham-aVNS) and SIT (p<0.05, vs. Sham-aVNS) impaired by loperamide. (b) aVNS increased plasma PP (p<0.01) and decreased plasma NE (p<0.01), compared with Sham-aVNS. (c) Gastric ICC was decreased by loperamide (p<0.01) but increased after aVNS (p<0.01, vs. Sham aVNS). Loperamide induces upper GI dysmotility. aVNS accelerates upper GI transit and improving pace-making activity mediated via the ICC. Non-invasive aVNS may have a therapeutic potential for upper GI dysmotility.

Effects of Flavonoids Extracted from Citrus aurantium on Performance, Behavior, and Rumen Gene Expression in Holstein Bulls Fed with High-Concentrate Diets in Pellet Form.

Simple SummaryCurrently, the beef production system faces important challenges, such as improving feed efficiency, reducing environmental impact, and improving animal welfare. Citrus flavonoids from bitter orange plant secondary metabolites are feed additives that have shown promising effects on intake modulation, efficiency, and improving animal behaviors related with animal welfare. However, as they interact with the digestive tract microbiota and the digestive tract receptors, their effects may be affected by the feeding method (mash or pellet). In the present study, when these flavonoids were fed in a pellet concentrate presentation form, the bull’s efficiency did not improve. However, animal behaviors related to welfare problems were reduced. Furthermore, supplementing bulls with flavonoids modified the expression in the rumen of genes concerned with behavior and inflammatory response. Therefore, supplementing bulls with citrus flavonoids may be a good strategy to improve their welfare.Flavonoid supplementation may modify the behavior and rumen inflammatory response of fattening bulls, and this could be related to the concentrate presentation (mash or pellet) form. In the present study, 150 Holstein bulls (183.0 ± 7.53 kg BW and 137 ± 1.8 d of age) were randomly allocated to one of eight pens and assigned to control (C) or (BF) (Citrus aurantium, Bioflavex CA, HealthTech Bio Actives, Spain, 0.4 kg per ton of concentrate of Bioflavex CA, 20% naringin). Concentrate (pellet) intake was recorded daily, and BW and animal behavior fortnightly. Animals were slaughtered after 168 d of study, and ruminal epithelium samples were collected for gene expression analyses. Treatment did not affect animal performance; however, BF supplementation reduced agonistic interactions and oral non-nutritive behaviors and increased the time devoted to eating concentrate and ruminating activity (p < 0.05). The gene expression of some genes in the rumen epithelium was greater or tended to be greater in BF than C bulls (bitter taste receptor 16, cytokine IL-25, β-defensin; p < 0.10; pancreatic polypeptide receptor 1 and tumor necrosis factor alpha; p < 0.05). In conclusion, flavonoid supplementation modifies the expression of genes in the rumen epithelium that could be related to inflammation and animal behavior modulation.

Acute pancreatitis-induced islet dysfunction in ferrets

Background/Objectives: The pathogenesis of hyperglycemia during acute pancreatitis (AP) remains unknown due to inaccessibility of human tissues and lack of animal models. We aimed to develop an animal model to study the mechanisms of hyperglycemia and impaired glucose tolerance in AP. MethodsWe injected ferrets with intraperitoneal cerulein (50 μg/kg, 9 hourly injections) or saline. Blood samples were collected for glucose (0, 4, 8, 12, 24h); TNF-α, IL-6 (6h); amylase, lipase, insulin, glucagon, pancreatic polypeptide (PP), glucagon-like peptide-1 (GLP-1), and gastric inhibitory polypeptide (GIP) (24h). Animals underwent oral glucose tolerance test (OGTT), mixed meal tolerance test (MMTT) at 24h or 3 months, followed by harvesting pancreas for histopathology and immunostaining. ResultsCerulein-injected ferrets exhibited mild pancreatic edema, neutrophil infiltration, and elevations in serum amylase, lipase, TNF-α, IL-6, consistent with AP. Plasma glucose was significantly higher in ferrets with AP at all time points. Plasma glucagon, GLP-1 and PP were significantly higher in cerulein-injected animals, while plasma insulin was significantly lower compared to controls. OGTT and MMTT showed abnormal glycemic responses with higher area under the curve. The hypoglycemic response to insulin injection was completely lost, suggestive of insulin resistance. OGTT showed low plasma insulin; MMTT confirmed low insulin and GIP; abnormal OGTT and MMTT responses returned to normal 3 months after cerulein injection. ConclusionsAcute cerulein injection causes mild acute pancreatitis in ferrets and hyperglycemia related to transient islet cell dysfunction and insulin resistance. The ferret cerulein model may contribute to the understanding of hyperglycemia in acute pancreatitis.

Metastatic Non-Functional Pancreatic Neuroendocrine Tumor in a Patient With a Pathogenic TSC1 Mutation

Abstract Introduction: Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem disorder caused by mutations in two tumor suppressor genes (TSC1 and TSC2) encoding proteins critical in cell growth and proliferation and is associated with an increased risk for benign and malignant tumors. Pancreatic neuroendocrine tumors (PNET) occur in 1.5-1.8% of patients with TSC. They have been primarily reported in TSC2, with only a few cases in the context of TSC1. We describe a non-functional metastatic PNET in a patient with a known pathogenic TSC1 mutation. Case Description: A 49-year old female with a past medical history of bipolar disease, a family history of TSC1 in a daughter, a known pathologic TSC1 mutation (c.2356C&amp;gt;T), and previous history of renal cell carcinoma (RCC) was evaluated for a pancreatic lesion with likely liver metastases. Two years prior to the presentation, a 10 mm pancreatic lesion was initially noted on the CT scan during a renal mass evaluation. Nephrectomy confirmed the RCC. Two years later, surveillance imaging revealed two new lesions in the liver, and the pancreatic lesion had enlarged to 1.3 cm. She denied symptoms suggestive of a functional PNET, and her physical exam was unremarkable. Gallium-68 dotatate (GA-68) PET/CT scan demonstrated avid lesions of both the pancreatic tail and left hepatic lobe. Biopsy of the 3 cm liver mass revealed a metastatic high-grade neuroendocrine carcinoma (mib-1 proliferation index of 15%) favoring a primary PNET. Immunohistochemical stains were positive for chromogranin A, synaptophysin, EMA, PAX 8, CK 20, and villin. Stains for CA 19-9 and CK 7 were negative. Biochemical testing suggested that the PNET was non-functional. Specifically, serum concentrations of gastrin, somatostatin, glucagon, glucose, C-peptide, proinsulin, pancreatic polypeptide, chromogranin A, and vascular endothelial growth factor were within normal limits. The patient underwent distal pancreatectomy and resection of the liver mass. Pathological specimens confirmed the diagnosis of a PNET. The patient remained asymptomatic and was monitored regularly with MRI and GA-68 PET/CT scans without further evidence of the disease for 1.5 years. Conclusions: We conclude that this patient harboring a c.2356C&amp;gt;T TSC1 mutation developed a non-functional metastatic PNET. PNET is a likely component of TSC1.

A Rare Case of Chronic Diarrhea in a Pediatric Patient

Background: VIPoma, also known as Watery Diarrhea-Hypokalemia- achlorhydria (WDHA) Syndrome is a rare manifestation of multiple endocrine neoplasia syndrome type 1 (MEN1). Vasoactive intestinal peptide, part of the secretin-glucagon family, may be overexcreted in tumors associated with MEN1 and results in diarrhea that persists while fasting, resulting in massive secretion of water and electrolytes. First-line treatment is surgical resection. Clinical Case: We present a 13-year-old male with a past medical history of chronic diarrhea for four years who was transferred from an outside hospital for severe diarrhea and associated electrolyte derangements, including hypokalemia of <1.0 mmol/L (3.5-5.0 mmol/L), sodium of 120 (135-145 mmol/L), and chloride of 84 mmol/L (101-110 mmol/L). Family history was significant for pancreatic, breast, thyroid, stomach, parathyroid, and uterine cancer, as well as hyperparathyroidism and nephrolithiasis. The patient had been admitted to the hospital before for a similar episode of acute on chronic diarrhea but was treated for infectious diarrhea during that admission. CT enterography was obtained during this hospitalization and it revealed multiple solid and heterogeneous appearing pancreatic masses in the head and tail of the pancreas. Work-up was significant for pancreatic polypeptide of 1,523 pg/mL (92-752 pg/mL) and vasoactive intestinal peptide of 1,105 pg/mL (<75 pg/mL). Pancreatic biopsy revealed a grade 2 pancreatic neuroendocrine tumor. Genetic testing revealed a known pathogenic mutation in the menin gene p.R526 (c. 1579>T, pArg527). A pylorus-preserving total pancreatectomy, duodenectomy, cholecystectomy, and splenectomy was performed and surgical pathology revealed a well-differentiated grade 1 neuroendocrine tumor in the head of the pancreas and a well-differentiated grade 2 neuroendocrine tumor in the tail of the pancreas. Since the surgery, the patient currently has no signs of other neuroendocrine tumors associated with MEN1 but continues to follow-up for regular screening for other tumors associated with MEN1. Clinical Lessons: 1. VIPoma, also known as Watery Diarrhea- Hypokalemia- Achlorhydria Syndrome, is characterized by secretory diarrhea that persists while fasting. 2. VIPoma should be considered in patients with a history of chronic diarrhea and a significant family history of neuroendocrine tumors.

Is Preptin a New Bone Metabolism Parameter in Hemodialysis Patients?

Background: Preptin is a bone-anabolic pancreatic peptide hormone. Its role in bone metabolism has been studied in rats and in patients with diabetes, but its levels and significance in bone metabolism in hemodialyzed (HD) patients is unknown. Methods: The relationships between preptin and anthropometric and biochemical parameters related to bone metabolism were studied in 73 patients on chronic hemodialysis (48 males, 25 females; mean age of 57 years; HD vintage of 69.7 months). Of these subjects, 36 patients had diabetes or impaired glucose tolerance (DM/IGT), and 37 patients had normal glucose tolerance (NGT). Dual-energy X-ray absorptiometry of the femoral neck and lumbar spine were also performed. Results: No differences were observed in preptin levels between DM/IGT and NGT HD patients. Preptin was positively correlated with HD vintage (r = 0.312, p = 0.007). Negative correlations between preptin and bone mineral density (BMD), T-score, and Z-score in the lumbar spine (L2-L4) were observed (r = −0.319, p = 0.009; r = −0.341, p = 0.005; r = −0.375, p = 0.002). Preptin was positively correlated with parathormone (PTH) levels (r = 0.379, p < 0.001) and osteocalcin levels (r = 0.262, p = 0.027). Conclusions: The results indicate that preptin may reflect on bone and mineral metabolism disturbances seen in HD patients. The significant correlation of preptin with PTH and osteocalcin suggests that preptin may be important in indirect measurement of bone turnover in HD patients.

Regulation of Pancreatic β-Cell Function by the NPY System.

The neuropeptide Y (NPY) system has been recognized as one of the most critical molecules in the regulation of energy homeostasis and glucose metabolism. Abnormal levels of NPY have been shown to contribute to the development of metabolic disorders including obesity, cardiovascular diseases, and diabetes. NPY centrally promotes feeding and reduces energy expenditure, while the other family members, peptide YY (PYY) and pancreatic polypeptide (PP), mediate satiety. New evidence has uncovered additional functions for these peptides that go beyond energy expenditure and appetite regulation, indicating a more extensive function in controlling other physiological functions. In this review, we will discuss the role of the NPY system in the regulation of pancreatic β-cell function and its therapeutic implications for diabetes.

Gastroenteropancreatic neuroendocrine neoplasms: A clinical snapshot.

Our understanding about the epidemiological aspects, pathogenesis, molecular diagnosis, and targeted therapies of neuroendocrine neoplasms (NENs) have drastically advanced in the past decade. Gastroenteropancreatic (GEP) NENs originate from the enteroendocrine cells of the embryonic gut which share common endocrine and neural differentiation factors. Most NENs are well-differentiated, and slow growing. Specific neuroendocrine biomarkers that are used in the diagnosis of functional NENs include insulin, glucagon, vasoactive intestinal polypeptide, gastrin, somatostatin, adrenocorticotropin, growth hormone releasing hormone, parathyroid hormone-related peptide, serotonin, histamine, and 5-hydroxy indole acetic acid (5-HIAA). Biomarkers such as pancreatic polypeptide, human chorionic gonadotrophin subunits, neurotensin, ghrelin, and calcitonin are used in the diagnosis of non-functional NENs. 5-HIAA levels correlate with tumour burden, prognosis and development of carcinoid heart disease and mesenteric fibrosis, however several diseases, medications and edible products can falsely elevate the 5-HIAA levels. Organ-specific transcription factors are useful in the differential diagnosis of metastasis from an unknown primary of well-differentiated NENs. Emerging novel biomarkers include circulating tumour cells, circulating tumour DNA, circulating micro-RNAs, and neuroendocrine neoplasms test (NETest) (simultaneous measurement of 51 neuroendocrine-specific marker genes in the peripheral blood). NETest has high sensitivity (85%-98%) and specificity (93%-97%) for the detection of gastrointestinal NENs, and is useful for monitoring treatment response, recurrence, and prognosis. In terms of management, surgery, radiofrequency ablation, symptom control with medications, chemotherapy and molecular targeted therapies are all considered as options. Surgery is the mainstay of treatment, but depends on factors including age of the individual, location, stage, grade, functional status, and the heredity of the tumour (sporadic vs inherited). Medical management is helpful to alleviate the symptoms, manage inoperable lesions, suppress postoperative tumour growth, and manage recurrences. Several molecular-targeted therapies are considered second line to somatostatin analogues. This review is a clinical update on the pathophysiological aspects, diagnostic algorithm, and management of GEP NENs.

The Chemical Synthesis of Insulin: An Enduring Challenge

The pancreatic peptide hormone insulin, first discovered exactly 100 years ago, is essential for glycemic control and is used as a therapeutic for the treatment of type 1 and, increasingly, type 2 diabetes. With a worsening global diabetes epidemic and its significant health budget imposition, there is a great demand for new analogues possessing improved physical and functional properties. However, the chemical synthesis of insulin's intricate 51-amino acid, two-chain, three-disulfide bond structure, together with the poor physicochemical properties of both the individual chains and the hormone itself, has long represented a major challenge to organic chemists. This review provides a timely overview of the past efforts to chemically assemble this fascinating hormone using an array of strategies to enable both correct folding of the two chains and selective formation of disulfide bonds. These methods not only have contributed to general peptide synthesis chemistry and enabled access to the greatly growing numbers of insulin-like and cystine-rich peptides but also, today, enable the production of insulin at the synthetic efficiency levels of recombinant DNA expression methods. They have led to the production of a myriad of novel analogues with optimized structural and functional features and of the feasibility for their industrial manufacture.

Hypoglycemic effects of Tibetan medicine Huidouba in STZ-induced diabetic mice and db/db mice

ObjectiveHuidouba (HDB) is a Chinese folk medicine used to treat diabetes in Sichuan Province, China. Therefore, we investigated the anti-diabetic effects of HDB and its underlying mechanisms. We hypothesized that HDB treatment could enhance glucose tolerance and insulin sensitivity, and thus prevent a hyperglycemia state. MethodsTo test the hypothesis, streptozotocin (STZ)-induced diabetic mice and db/db mice, widely used models of hyperglycemia and insulin-resistant diabetes, were either treated with HDB, metformin, or acarbose. Blood glucose, oral glucose tolerance test, insulin tolerance test, pancreatic histopathology and serum biochemistry were detected to assess the hypoglycemic effect of HDB. ResultsHDB treatments were found to show the effect in reducing glucose levels. HDB also resulted in a significant reduction in body weight and food intake in the STZ-induced diabetic mouse model. Furthermore, it significantly improved glucose and insulin tolerance in the two diabetic mouse models. Importantly, insulin, glucagon, pancreatic polypeptide, and somatostatin immunohistochemistry revealed that HDB treatment improved the function and the location of the cells in the islets compared with the other two treatments. HDB treatment resulted in significant restoration of islet function. Our results illustrated the underlying mechanism of HDB in the progression of diabetes, and HDB can be an effective agent for the treatment of diabetes. ConclusionThe results of this study suggested that HDB can reduce blood glucose levels in STZ-induced hyperglycemic mice and db/db mice.