c-peptide and Endocrine-System-Diseases

Gut peptide secreting tumours originate most commonly from the pancreatic Islets of Langerhans. Tumours at a variety of other sites have also been shown to synthesize and release these peptides, reflecting the wide distribution of the peptide secreting cells of the diffuse neuroendocrine system. Tumours such as the glucagonomas, insulinomas, VIPomas and gastrinomas are associated with characteristic clinical syndromes resulting from the effects of the peptide they secrete. The majority of the islet cell tumours in fact secrete a number of different peptides and many of these are present in several molecular forms, some of which may not be biologically active. This may explain the lack of clinical sequelae in association with tumours such as the somatostatinomas. The clinical features, methods of diagnosis, localisation and treatment of these tumours will be discussed.

Topics: Adenoma, Islet Cell; Bombesin; Bronchial Neoplasms; C-Peptide; Carcinoma, Small Cell; Diagnosis, Differential; Endocrine System Diseases; Erythema; Gastrointestinal Hormones; Glucagon; Glucagonoma; Humans; Insulin; Insulin Secretion; Insulinoma; Male; Neoplasms; Neurotensin; Pancreatic Hormones; Pancreatic Neoplasms; Pancreatic Polypeptide; Somatostatinoma; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

Although physical activity is an established risk factor for chronic disease prevention, the specific mechanisms underlying these relationships are poorly understood. We examined the associations between total activity counts and moderate-vigorous physical activity (MVPA) measured by accelerometer, and physical activity energy expenditure measured by doubly labeled water, with plasma levels of proinsulin, insulin, c-peptide, insulin growth factor binding protein-3, insulin growth factor-1, adiponectin, leptin, and leptin-sR.. We conducted a cross-sectional analysis of 526 healthy US women in the Women's Lifestyle Validation Study, 2010 to 2012. We performed multiple linear regression models adjusting for potential lifestyle and health-related confounders to assess the associations between physical activity, measured in quartiles (Q) and biomarkers.. Participants in Q4 versus Q1 of total activity counts had lower proinsulin (-20%), c-peptide (-7%), insulin (-31%), and leptin (-46%) levels, and higher adiponectin (55%), leptin-sR (25%), and insulin growth factor-1 (9.6%) levels (all P trend ≤ 0.05). Participants in Q4 versus Q1 of MVPA had lower proinsulin (-26%), c-peptide (-7%), insulin (-32%), and leptin (-40%) levels, and higher adiponectin (31%) and leptin-sR (22%) levels (all P trend ≤ 0.05). Further adjustment for body mass index (BMI) attenuated these associations, but the associations with adipokines remained significant. Those in Q4 versus Q1 of physical activity energy expenditure had lower leptin (-21%) and higher leptin-sR (10%) levels (all P trend ≤ 0.05), after additional adjustment for BMI. In the sensitivity analysis, the associations were similar but attenuated when physical activity was measured using the subjective physical activity questionnaire.. Our data suggest that greater physical activity is modestly associated with favorable levels of cardiometabolic and endocrine biomarkers, where the strongest associations were found with accelerometer-measured physical activity. These associations may be only partially mediated through BMI, further supporting the role of physical activity in the reduction of cardiometabolic and endocrine disease risk, independent of adiposity.

Topics: Accelerometry; Adiponectin; Aged; Biomarkers; Body Mass Index; C-Peptide; Cardiovascular Diseases; Cross-Sectional Studies; Endocrine System Diseases; Energy Metabolism; Exercise; Female; Humans; Insulin; Insulin-Like Growth Factor Binding Protein 3; Insulin-Like Growth Factor I; Leptin; Middle Aged; Proinsulin; Risk Factors

C-peptide is cleaved from the proinsulin chains A and B during insulin synthesis. The views on its role in human physiology has changed in recent years. Soon after discovery of C-peptide it was believed that this protein is inactive by-product of insulin synthesis, and its role is limited to role in conformational changes of insulin and indicator of exocrine function of the pancreas. At present, it is known that C-peptide is bioactive compound, with multiple functions, and it acts probably through membrane receptor. The known physiological actions of C-peptide are related mainly to kidneys, circulatory and nervous systems function. In kidney, it changes the glomerular filtration and proteinuria. In blood vessels, C-peptide is able to act as a vasodilator. It is also able to improve the neurotransmission rate. The newest data indicates possible involvement of C-peptide in etiopathology of diabetes and polycystic ovary syndrome. The possible role of C-peptide in these disorders is very interesting and requires further studies.

Topics: C-Peptide; Diabetes Mellitus; Endocrine System Diseases; Female; Glomerular Filtration Rate; Humans; Insulin; Pancreas; Polycystic Ovary Syndrome; Proinsulin; Vasodilation