Pancreatic Polypeptide, human

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 (sporadicvsinherited). 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.

Purpose:Pancreatic polypeptide (PP) has important glucoregulatory functions and thereby holds significance in the treatment of diabetes and obesity. However, short plasma half-life and aggregation propensity of PP in aqueous solution, limits its therapeutic application. To address these issues, we prepared and characterized a formulation of PP in sterically stabilized micelles (SSM) that protects and stabilizes PP in its active conformation.Methods:PP-SSM was prepared by incubating PP with SSM dispersion in buffer. Peptide-micelle association and freeze-drying efficacy of the formulation was characterized in phosphate buffers with or without sodium chloride using dynamic light scattering, fluorescence spectroscopy and circular dichroism. The degradation kinetics of PP-SSM in presence of proteolytic enzyme was determined using HPLC and bioactivity of the formulation was evaluated by in vitro cAMP inhibition study.Results:PP self-associated with SSM and this interaction was influenced by presence/absence of sodium chloride in the buffer. The formulation was effectively lyophilized, demonstrating feasibility for its long-term storage. The stability of peptide against proteolytic degradation was significantly improved and PP in SSM retained its bioactivity in vitro.Conclusions:Self-association of PP with phospholipid micelles addressed the delivery issues of the peptide. This nanomedicine should be further developed for the treatment of diabetes.

Objectives:Human pancreatic polypeptide (HPP) is a hormone secreted by the ventral pancreas. While postprandial HPP levels have been studied in chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC), there are limited data on fasting HPP in these diseases.Methods:Fasting serum HPP was measured in the following groups of patients: CP with diabetes mellitus (DM) (n = 16), CP without DM (n = 34), PDAC with new-onset DM (n = 50), PDAC without DM (n = 49), new-onset type 2 DM (n = 50), and controls without DM (n = 49). Sixty-six had type 3c DM (CP with DM, n = 16; PDAC with new-onset DM, n = 50).Results:Median fasting HPP levels (in picograms per milliliter) were similar among all groups. Median (interquartile range) HPP levels in new-onset type 2 DM (n = 50; 288.3 [80.1-1072.1]) were similar to those in type 3c DM (n = 66; 242.3 [64.9-890.9]) (P = 0.71). In PDAC (n = 99), HPP values were similar in pancreatic head (n = 75) versus body/tail (n = 24) tumors (245.3 [64.3-1091.3] vs 334.7 [136.1-841.5]; P = 0.95), regardless of DM.Conclusions:Fasting HPP levels are similar in CP, PDAC, and controls regardless of glycemic status.