Hyperglucagonaemia in the surgical patient.

Twenty-one patients had serial samples of blood taken before, during, and after operation for the measurement of plasma glucagon, plasma insulin, and blood glucose concentrations. A significant rise in plasma glucagon level was noted during the operation. In contrast the plasma insulin concentration fell during the operation and rose in the postoperative period despite hyperglycaemia during and after the operation. These findings show that hyperglucagonaemia is a physiological consequence of a surgical operation and that the relationship of plasms glucagon to plasma insulin is complex.     

Plasma Glucagon Levels Suppressed by a Glucose Load in a Man with Incidental Pancreatic Glucagonoma

ObjectiveTo describe a patient with a histologically proven pancreatic glucagonoma, noted incidentally during a follow-up visit for high aminotransferase levels, and to evaluate its autonomy with a standard 75-g oral glucose tolerance test.MethodsWe present the results of a 2-hour oral glucose tolerance test, with plasma glucagon and blood glucose levels measured every 30 minutes after an oral glucose load. In addition, we provide a brief review of the literature on the diagnosis and management of glucagonomas and the importance of long-term surveillance.ResultsIn our patient, who had a 1-year history of impaired fasting glucose, plasma glucagon levels were persistently suppressed to within the normal range after oral glucose challenge. Octreotide scintigraphy revealed abnormal uptake in the pancreatic tail, and a 2.8-cm mass was removed at laparoscopic distal pancreatectomy. Immunohistochemical staining of the tumor tissue showed intense reactivity for glucagon. Plasma glucagon levels were reduced to < 50 pg/mL postoperatively, and scintigraphic study at 4-month follow-up showed no residual uptake at the previous tumor site or elsewhere.ConclusionGlucagon-secreting pancreatic tumors are extremely rare. A substantially elevated plasma level of glucagon is usually seen in patients with metastatic tumors. In the early stage of a glucagonoma, however, the plasma glucagon level may be only modestly elevated and may still be susceptible to normal negative feedback inhibition. We demonstrated plasma glucagon complete suppressibility after oral glucose challenge in a patient with a glucagonoma, the first such report in the literature. (Endocr Pract. 2007;13:780-784)     

GPR40 is expressed in glucagon producing cells and affects glucagon secretion

The free fatty acid receptor, GPR40, has been coupled with insulin secretion via its expression in pancreatic beta-cells. However, the role of GPR40 in the release of glucagon has not been studied and previous attempts to identify the receptor in alpha-cells have been unfruitful. Using double-staining for glucagon and GPR40 expression, we demonstrate that the two are expressed in the same cells in the periphery of mouse islets. In-R1-G9 hamster glucagonoma cells respond dose-dependently to linoleic acid stimulation by elevated phosphatidyl inositol hydrolysis and glucagon release and the cells become increasingly responsive to fatty acid stimulation when overexpressing GPR40. Isolated mouse islets also secrete glucagon in response to linoleic acid, a response that was abolished by antisense treatment against GPR40. This study demonstrates that GPR40 is present and active in pancreatic alpha-cells and puts further emphasis on the importance of this nutrient sensing receptor in islet function.     

Danazol therapy renders red cells resistant to osmotic lysis

Danazol, an attenuated androgen, is useful in endometriosis, idiopathic thrombocytopenic purpura (ITP), and autoimmune hemolytic anemia (AIHA). However, its mechanism of action is unknown. We investigated the possibility that danazol affects cell membranes directly. Red cell osmotic fragility was studied in patients receiving danazol. A significant decrease in osmotic fragility was observed. Accompanying the change, peripheral blood smears showed many target cells and electron microscopy revealed extra folds in erythrocyte membranes. Twenty-two patients were studied prospectively before and after danazol. Osmotic fragility decreased significantly (P less than 0.001) in 1 month of therapy and progressed with further treatment. A rebound increase (P less than 0.01) was observed in 1 month after discontinuation of danazol among 16 patients. Incubation experiments showed that danazol-induced changes are not reversed with normal sera. Patient sera did not induce the changes in normal red cells. Danazol in vitro protected red cells from osmotic lysis at low concentrations but enhanced lysis at high concentrations. We suggest that danazol alters red cell membranes directly to increase their surface area, inducing target cell formation and increasing their resistance to osmotic lysis.     

A case with glucagonoma syndrome--endocrine and metabolic studies

The results of clinical endocrine and metabolic studies on a 57-year-old female with surgically and autopsy verified glucagonoma syndrome were presented. All of the clinical manifestations of glucagonoma syndrome so far reported in the literature were noted but there was no evidence indicating the presence of multiple endocrine adenomatosis. The plasma IRG level was always more than 20 times above the normal, and the IRG response to insulin and tolbutamide injection was abnormal and the results of the other endocrinological studies revealed less remarkable features, if any. The surgically removed metastatic tumor of the liver contained an enormous amount of IRG and an appreciable amount of IRI, indicating that the elevated plasma IRG was mainly of tumor origin. These results clearly indicate that in glucagonoma there is some abnormality in glucagon release from the tumor. In addition to these findings, hypocalcemia, cardiac left ventricular hypertrophy and gastrointestinal dysfunction reportedly due to hyperglucagonemia were also seen in this patient.     

Glucagon Treatment for Post‐Gastric Bypass Hypoglycemia

Hyperinsulinemic hypoglycemia is a recently described complication of Roux‐en‐Y gastric bypass (RYGB). We hypothesized that glucagon administration would help maintain normal postprandial plasma glucose concentrations by stimulating hepatic glucose output, and if so, represent a new therapeutic option for postbypass hypoglycemia. In this study, we compared the insulin and glycemic response to a mixed meal with and without concomitant glucagon infusion in a patient with severe recurrent hypoglycemia after RYGB. Although effective in transiently raising postprandial plasma glucose values, glucagon infusion was also associated with higher insulin concentrations, and failed to prevent symptomatic hypoglycemia. This case demonstrates that glucagon may have limited clinical utility in the treatment of post‐RYGB hyperinsulinemic hypoglycemia.     

Secretory response and immunochemical heterogeneity of glucagon in plasma and tumor extracts of a patient with glucagonoma

The secretory response and immunoreactive heterogeneity of glucagon was investigated in a patient with glucagonoma syndrome. After glucose administration, abnormal insulin release accompanied by glucose intolerance were observed, whereas the high glucagon circulating levels were only partially blocked after glucose or somatostatin infusion. Chromatographic fractionation of plasma samples, before and after arginine administration showed that most of the immunoreactivity eluted as true glucagon. Furthermore, when aliquots of the tumor extracts were fractionated by column chromatography or by polyacrylamide gel electrophoresis, most of the immunoreactivity eluted in the 3,500 molecular weight peak. In contrast with previous reports, our results indicate that neoplasia A cells can also manufacture and release into the bloodstream great amounts of genuine glucagon rather than larger glucagon immunoreactive forms. In spite of such findings, in this patient neither diabetes nor hyperglycemia were present.     

Multiple hormone secretion by a human pancreatic glucagonoma in culture

A patient presenting clinically with the glucagonoma syndrome had high plasma glucagon levels (1920 ng/l) and at laparotomy, a pancreatic islet cell tumour was removed. The tumour was dispersed and placed in culture where it remained viable for 63 days. The tumour cells secreted immunoreactive (IR) glucagon at levels up to 2400 ng/l as detected by a C-terminal glucagon specific antibody and 85 400 ngequiv./l as measured by an N-terminal glucagon specific antibody. The difference between these two levels was attributed to the presence of different molecular forms of glucagon measured with the N-terminal specific antibody. IR insulin (up to 302 mU/l) and IR somatostatin (up to 2500 ng/l) were also detected. There was no direct or inverse correlation between different hormone levels. Small but significant levels of N-terminal and C-terminal vasoactive intestinal peptide (VIP) were detected in some cultures but there was no evidence of gastrin or ACTH. Glucagon and somatostatin secretion persisted for the duration of the culture (63 days) but insulin concentrations declined. Incubation of cultures with somatostatin (1 ng/ml) caused a 75% decrease in glucagon levels, while insulin (1000 mU/l) produced a 70% inhibition of somatostatin.     

Metabolic abnormalities in children of non-insulin dependent diabetics.

Non-insulin dependent diabetes appears to be an inherited condition. A study of young offspring of non-insulin dependent diabetics was conducted to determine whether metabolic abnormalities could be found at a young age before clinical diabetes developed. Thirteen patients with non-insulin dependent diabetes were selected who fulfilled the following criteria: they had a sibling who also had non-insulin dependent diabetes, their spouse was non-diabetic, and the offspring were aged between 12 and 45 years, not diabetic, and available for study. All 32 offspring had a 75 g oral glucose tolerance test, and results in 13 of them, one randomly selected from each family, were compared with 13 controls of similar age, sex, and weight. The offspring had significantly higher fasting concentrations of glucose, higher proportions of haemoglobin A1, and higher concentrations of insulin, C peptide, and glucagon. After glucose challenge the increases in both glucose and C peptide concentrations were significantly greater in the offspring. These differences were maintained in all 32 offspring when compared with 18 controls of similar age, sex, and weight; seven of the 32 offspring had impaired glucose tolerance. These results indicate that young offspring of selected non-insulin dependent diabetics can show extensive metabolic changes including impaired glucose tolerance. These changes are associated with hyperinsulinaemia and hyperglucagonaemia.     

Morphological changes in the human endocrine pancreas induced by chronic excess of endogenous glucagon.

The non-tumoral endocrine pancreas from a patient with elevated plasma levels of glucagon due to a malignant glucagonoma was studied immunocytochemically, ultrastructurally and morphometrically. Compared with normal pancreatic islets from control subjects, those of the pancreas from the patient with a glucagonoma showed an almost complete disappearance of A cells, a decrease in immunoreactive insulin in B cells associated with cytological features indicating enhanced synthesis and secretion of this hormone, and an increase in immunoreactive somatostatin and pancreatic polypeptide (PP) accompanied by unusually high numbers of D and PP cells. In addition, numerous B cells were found outside the islets, either forming micro-islets or scattered in the exocrine tissue (nesidioblastosis). The possible mechanisms involved in determining the changes in the secretory activity of B cells and the alterations in the cell composition of the islets are discussed.     

Immunosuppressive Therapy in Patients with Aplastic Anemia: A Single-Center Retrospective Study

BackgroundAplastic anemia (AA) is a rare disease in which hematopoietic stem cells are severely diminished resulting in hypocellular bone marrow and pancytopenia. Etiology of AA includes auto immunity, toxins, infection, ionizing radiation, drugs and rare genetic disorders, but in the majority of cases no cause can be identified. In the present study we assessed response rate, survival, relapse and clonal evolution in patients with AA treated with immunosuppressive therapy.MethodsPatients with AA who received immunosuppressive therapy between May 1998 and September 2013 were included in this study. Patients with non-severe AA (NSAA) were treated with cyclosporine (CsA) and danazol while patients with severe AA (SAA) as well as patients with NSAA who progressed to SAA after beginning of the treatment, were candidates for receiving antithymocyte globulin in addition to CsA and danazol.ResultsAmong the 63 studied patients, 29 (46%) had NSAA and 34 (54%) had SAA. Three months after treatment, overall response was 58.6% in NSAA and 12.9% in patients with SAA. Survival of all patients at 5, 10 and 15 years were 73%, 55% and 49%, respectively. Survival rates were significantly higher in patients with NSAA compared to patients with SAA as well as in patients who responded at 6 months compared to non-responders. The relapse risk was 39.7% at 10 years. Relapse occurred in patients who discontinued the therapy more than those who continued taking CsA (p value<0.01). The risk of clonal evolution was 9.9% at 10 years and 22.8% at 15 years after treatment.ConclusionThis long-term retrospective study indicated that immunosuppressive therapy should be recommended to patients with AA. Also, our experience indicated that immunosuppressive therapy should not be discontinued after response to therapy in patients with both NSAA and SAA due to high risk of relapse. Low dose of CsA should be continued indefinitely.     

The interaction of glucagon treatment and uncoupler concentration on ATPase activity of rat liver mitochondria

Mitochondria isolated from livers of rats treated briefly with glucagon show an increased ATPase activity in the presence of appropriate concentrations of protonophoric uncouplers (Yamazaki, R. K., Sax, R.D., and Hauser, M.A. (1977) FEBS Lett. 75, 295-299). With the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) the effect of glucagon treatment was most evident at concentrations of uncoupler higher than required for maximal stimulation of ATPase in control mitochondria. In this range of FCCP concentrations that produced the greatest contrast in ATPase activity of control and hormone-stimulated mitochondria, there were no significant differences in delta pH, delta psi, or delta p between the two groups. The presence of added succinate in the ATPase assay system mimicked the effect of glucagon treatment, permitting greater activity at high concentrations of uncoupler without significantly affecting delta p. No significant effect of glucagon treatment or uncoupler concentrations on mitochondrial volumes was observed. Following treatment with glucagon, the mitochondria retained a greater content of Mg+ and K+ throughout the range of FCCP concentrations tested. In the upper range of FCCP concentrations there was appreciable loss of K+ from the mitochondria which was greater in control mitochondria than in mitochondria from glucagon-treated rats or in mitochondria assayed in the presence of succinate. The activity of the uncoupler-dependent ATPase was greatly stimulated by increased concentrations of potassium chloride in the assay medium without significantly diminishing the hormone effect. It is proposed that the intrinsic peptide inhibitor of ATPase is dissociated from the enzyme to an increased degree following glucagon treatment and that high levels of uncoupler inhibit by causing an increased association of the enzyme and its inhibitor.     

Metabolic consequences of atenolol and propranolol in treatment of essential hypertension.

A six-month study of triglyceride, cholesterol, free fatty acid (FFA), glucose, insulin, growth hormone, and glucagon concentrations was carried out in asymptomatic hypertensive normal-weight men randomly allocated to treatment with atenolol or propranolol. A highly significant increase in the basal plasma triglyceride concentration was observed in propranolol-treated patients after three and six months'' treatment, with a smaller but significant increase in atenolol-treated subjects after six months'' treatment. The changes in triglyceride concentration could not be ascribed to variations in plasma insulin, growth hormone, or glucagon concentrations. Basal FFA concentrations were reduced during the first three months of treatment in both groups but returned to pretreatment levels after six months. Plasma cholesterol concentrations were unchanged by either agent.     

A case with glucagonoma syndrome--heterogeneity of glucagon and insulin

The heterogeneity of glucagon and insulin in plasma and tissue extracts from a 57-year-old female with glucagonoma syndrome with surgically and autopsy verified islet-cell tumors was studied by Bio-Gel P-10 filtration. The preoperative plasma immunoreactive glucagon (IRG) level was 20.2 ng/ml, and plasma glucagon-like immunoreactivity(GLI) 25.8 ng/ml. The column chromatography of the preoperative plasma revealed three or four IRG components and four GLI components. Among these, peak II, the large glucagon immunoreactivity (LGI) peak, considered a candidate for proglucagon, was prominent, along with peak III. The resected metastatic liver tumor contained an enormous amount of IRG and an appreciable amount of immunoreactive insulin (IRI), indicating that the elevated plasma IRG was mainly of tumor origin. The IRG pattern of the tumor tissue extract revealed a small quantity of IRG in peaks I and II, and a large amount in peak III; control pancreatic tissue extract manifested a similar elution pattern. The IRI elution pattern of the tumor tissue extract revealed two major IRI peaks which migrated close to the elution volume of cytochrome C and insulin, respectively. This is a quite different pattern from the control pancreatic tissue extract in which the RI peak was localized in the elution volume of the insulin. We conclude that the present metastatic liver tumor produced not only enormous amounts of glucagon but heterogeneous peptides which contained immunological insulin determinants within their.     

Biphasic effect of danazol on human vascular endothelial cell permeability and f-actin cytoskeleton dynamics

Breakdown of endothelial barrier function is a hallmark event across a variety of pathologies such as inflammation, cancer, and diabetes. It has also been appreciated that steroid hormones impart direct biological activity on endothelial cells at many levels. The purpose of this investigation was to explore the effect of the androgen-like steroid, danazol, on endothelial cell barrier function in vitro. Primary human endothelial cells exposed to 0.01-50 μM danazol were evaluated for changes in permeability. We found that danazol altered endothelial permeability in a biphasic manner in which nanomolar concentrations enhance barrier function while micromolar concentrations are detrimental. Monitoring of trans-endothelial electrical resistance demonstrated that these barrier enhancing effects were rapid (within 5 min) and lasted for over 24h. Analysis of intracellular f-actin organization showed that barrier enhancement also correlated with the formation of a submembranous cortical actin ring. Conversely, at higher danazol concentrations, contractile cell phenotypes were observed, represented by stress fiber formation. Competitive binding studies performed using steroid hormone receptor antagonists proved that this activity is the result of androgen and estrogen receptor ligation. These findings suggest that low dose danazol may provide a therapeutic window for diseases involving vascular leakage.