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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatic plasma membranes prepared from rats rendered diabetic by streptozotocin bound approximately twice as much insulin per 50 mug protein as control membranes. Glucagon binding of diabetic and control membranes was virtually identical. This increased insulin binding was not due to a nonspecific effect of streptozotocin, decreased degradation of insulin slower dissociation from its receptor, or a selective higher yield of membranes prepared from the diabetic livers. Diabetic and control membranes both showed negative cooperativity. Scatchard analysis suggested that the difference in binding was due to an enhanced binding capacity of the diabetic membranes rather than increased affinity of the binding sites. Increased insulin binding of diabetic membranes was returned to normal by insulin treatment. These data are consistent with the postulate that there is an inverse relationship between circulating insulin levels and insulin binding and that insulin may modulate its own receptor. However, since it has been reported that fat, muscle, and hepatic tissue from rats made diabetic by alloxan administration are insensitive to insulin, the capacity for binding can not be the sole factor determining the response to insulin in diabetes mellitus. Therefore, sensitivity of the diabetic liver to insulin is determined, at least in part, by events subsequent to the binding of insulin to its receptor.
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PMID:Increased insulin binding by hepatic plasma membranes from diabetic rats: normalization by insulin therapy. 13 48

Glycogen accumulates in human fetal liver beginning at the eighth week of gestation. A parallel increase in total glycogen synthase activity is found, although the I-form activity remains low and constant throughout the first two thirds of gestation. Total phosphorylase activity increases slightly during this period, with the proportion in the active form amounting to about one half of the total throughout. After an initial rapid decline, the glycogen concentration in explants of human fetal liver remained constant for twenty to forty hours at about 20 per cent of the in vivo level. Incubation with glucagon, cyclic AMP (adenosine 3',5'-monophosphate) or its dibutyryl derivative markedly reduced tissue glycogen concentrations while insulin brought about a small increase. The effect of maximal doses of dibutyryl cyclic AMP and glucagon were the same, and the combination of agents produced no further effect. The response to dibutyryl cyclic AMP was apparent by one hour and maximal by three to six hours, whereas the response to insulin required about six hours to be detected, and it continued for at least eighteen hours. Insulin antagonized the glycogenolytic effect of low doses of glucagon or theophylline but was without significant effect in the presence of high glucagon concentrations. Glucagon stimulated cyclic AMP output from explants, and this effect was further augmented by theophylline. Insultin had no consistent effect on cyclic AMP output in either the presence or the absence of glucagon or theophylline. Incubation with dibutyryl cyclic AMP resulted in a decrease of glycogen synthase I-form activity, while insulin tended to increase this enzyme activity. In neither circumstance was the proportion of active phosphorylase altered. These results suggest that the regulation of glycogen levels in human fetal liver by cyclic AMP, glucagon, and insulin may entail alterations in the activity of glycogen synthase activity without necessitating alterations in phosphorylase activity. Cyclic AMP or glucagon was capable of depleting tissue glycogen stores in tissue from fetuses of six weeks' gestation. Insulin increased tissue glycogen concentrations in tissue from fetuses of seven or more weeks.
Diabetes 1975 Dec
PMID:Hormonal regulation of glycogen metabolism in human fetal liver. I. Normal development and effects of dibutyryl cyclic AMP, glucagon, and insulin in liver explants. 17 97

The effects of glucagon on tissue and plasma cyclic AMP levels have been investigated in rabbits anesthetized with urethane. Glucagon (2 nmole/kg.) caused at least a twofold increase in hepatic cyclic AMP, which reached a peak within two minutes and declined to basal values after 40 minutes. Plasma cyclic AMP also increased at least twofold, reaching a peak at 10 minutes and declining to basal values after 60 minutes. Glucagon (20 nmole/kg.) stimulated hepatic and plasma cyclic AMP in a manner indistinguishable from that observed at the lower dose. Hepatectomy abolished the plasma cyclic AMP responses to glucagon, and no significant stimulation of cyclic AMP concentration was noted in the heart, adipose tissue, small bowel, or kidney. Cyclic AMP hydrolysis was estimated in blood taken before and after administration of glucagon. Glucagon (2 nmole/kg.) increased cyclic AMP hydrolysis slightly, but this was explained by the raised cyclic AMP levels. By contrast, cyclic AMP hydrolysis increased two-to-threefold in blood taken 20 and 40 minutes after glucagon (20 nmole/kg.). The higher dose of glucagon also stimulated cyclic AMP hydrolysis in crude liver homogenate, which could not be explained by increases in cyclic AMP concentration. The increase in cyclic AMP hydrolysis observed in blood and liver may partly explain the failure to show additional stimulation of hepatic and plasma cyclic AMP levels with the higher dose of glucagon. Despite the changes in cyclic AMP hydrolysis, a highly significant correlation was observed in individual rabbits between the hepatic and plasma cyclic AMP responses to glucagon (2 and 20 nmole/kg.), when these were calculated as incremental areas above mean basal levels. It is suggested that measurement of plasma cyclic AMP levels after stimulation by glucagon may be an accurate index of the hepatic cyclic AMP response to glucagon in vivo.
Diabetes 1977 Feb
PMID:The cyclic AMP response to glucagon. Comparison of tissue and plasma cyclic AMP levels in the rabbit. 19 72

Insulin can modulate glucagon-stimulated hepatic glucose production and is considered to be the major factor acting in vivo to exert a couterregulatory action to glucagon. The insulin-dependent diabetic, therefore, might be especially vulnerable to enhanced hepatic glucose production promoted by glucagon. To investigate this hypothesis, low-dose glucagon infusions were administered to normal and diabetic men to compare the effects of glucagon on net splanchnic glucose production (NSGP). Four normal and three insulin-dependent, ketosis-prone, hyperglycemic diabetic men (insulin withheld for 24 hours) underwent brachial-artery-hepatic-vein catheterization. Each received a 90-minute glucagon infusion at 5 ng/kg./min. Glucagon levels rose four-to-fivefold in both groups, plateauing at 300-600 pg./ml. In the normals, NSGP rose from 92+/-12 to 211+/-31 mg./min. at 15 minutes and returned to basal levels by 45 minutes. Insulin measured in the hepatic vein rose from 19+/-6 to 33+/-11 muU/.ml., while plasma glucose rose 17 mg./dl. In the insulin-dependent diabetics, NSGP rose from 78+/-24 to a peak of 221+/-33 mg./min. at 30 minutes and then fell sharply to 113+/-15 mg./min. at 60 minutes despite continuing hyperglucagonemia. Plasma glucose in the diabetics rose 21 mg./dl. These data suggest a mechanism that acts to rapidly diminish glucagon-induced hepatic glucose production in diabetic man but does not appear to be mediated by increased insulin secretion.
Diabetes 1977 Mar
PMID:Transient stimulatory effect of sustained hyperglucagonemia on splanchnic glucose production in normal and diabetic man. 19 74

Liver protein kinase was determined in the absence and presence of cAMP4. Experimental alloxan diabetes resulted in a decrease in total protein kinase (+cAMP) and an increase in the activity ratio (-cAMP) divided by (+cAMP) in liver. Insulin treatment of diabetic rats reversed the observed changes in protein kinase in liver. Glucagon administered in vivo to normal rats caused an increase in the activity ratio and a decrease in total protein kinase activity in liver. The changes are similar to those in diabetes. A decrease in the ratio of insulin to glucagon in diabetes may account for the changes in protein kinase observed.
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PMID:Effect of experimental diabetes and glucagon on cAMP-dependent protein kinase in rat liver. 19 20

Glucagon-secreting tumors of the pancreatic islets (glucagonomas) produce a distinctive syndrome in which weight loss, diabetes mellitus, anemia,and prominent mucocutaneous findings occur. The cutaneous component-necrolytic migratory erythema--may be polymorphous, but most commonly manifests as erosions and crusts of the groin, perineum, buttocks, distal part of the extremities, and central area of the face. Alternatively, scaly papules and plaques may predominate in these areas. The eruption may resemble such dermatoses as pemphigus foliaceus, acrodermatitis enteropathica, chronic mucocutaneous candidiasis, psoriasis, and severe seborrheic dermatitis. Two patients with chronic, previously undiagnosed dermatoses had necrolytic migratory erythemia, which led to the discovery of glucagonomas present in each. In one patient surgical resection of the tumor resulted in total clearing of the rash within 48 hours. Awareness of this distinctive entity may lead to early diagnosis and, possibly, cure.
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PMID:Necrolytic migratory erythema. Distinctive dermatosis of the glucagonoma syndrome. 19 37

With the advent of radioimmunoassay and immunocytochemical methods, the peptides of the gastrointestinal tract have been identified and measured. Gastrinoma and insulinoma syndromes have been wall characterized. The pancreatic cholera syndrome and some of the evidence that the major manifestations of this disease may be mediated by vasoactive intestinal peptide have been re-examined. Pancreatic polypeptide seems to be an ideal peptide for study of vagal-cholinergic mechanisms that regulate hormone release; it also appears to be a tumor marker for several types of pancreatic endocrine tumors, particularly those of pancreatic cholera. Secretin and cholecystokinin are important regulators of pancreatic exocrine secretion and have been used to test pancreatic function, but there is little evidence that they account for clinical disease. Glucagon-secreting tumors produce a clinical syndrome of diabetes mellitus and distinctive skin lesions, which can be cured by tumor resection. Hormone-secreting tumors may provide insight into normal gut physiology.
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PMID:Gastrointestinal hormones in clinical disease: recent developments. 21 42

A 34-year-old man presented with classic glucagonoma syndrome manifested by weight loss, dermatitis, stomatitis, anemia, and mild diabetes mellitus. The diagnosis of glucagonoma was made by light and electron microscopic demonstration of a metastatic alpha cell carcinoma in a liver biopsy specimen. Plasma glucagon concentration was abnormally high. The patient also had symptoms and signs of involvement of the central nervous system. Radionuclide and CAT scans of the brain, negative CSF cytology and myelography excluded the possibility of metastases or other space-occupying lesions. Glucagon was demonstrated in the CSF. We postulate that the neurologic symptoms were due to direct or indirect effect of this hormone on the brain. Following therapy with streptozotocin and 5-fluorouracil, the patient had a subjective and objective clinical and hormonal remission of his disease including amelioration of his neurological impairment.
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PMID:Neurologic involvement in glucagonoma syndrome: response to combination chemotherapy with 5-fluorouracil and streptozotocin. 22 32

The A-, D-, and B-cells--the islet cells that contain, respectively, immunoreactive glucagon, somatostatin, and insulin--are distributed within a specialized heterocellular region of the islets of Langerhans as if to permit heterologous contacts between all three cell types. Inasmuch as each one of the three secretory products of these three cell types influences the secretion of at least one of its neighboring cells, "paracrine" influence on islet hormone secretion becomes a reasonable hypothesis. Glucagon stimulates both insulin and somatostatin release, while insulin and somatostatin both inhibit glucagon release, providing the basis for a feedback relationship through which A-cell secretion may be restrained. In addition, glucagon-mediated insulin secretion may be estrained by glucagon-stimulated somatostatin release. Such intercellular relationships could help determine the composition of the insulin and glucagon mistures released within a given metabolic setting.
Diabetes 1977 Mar
PMID:Possible roles of the pancreatic D-cell in the normal and diabetic states. 32 77

In order to correlate the different cell types of the human endocrine pancreas to a specific secretion product, an immunoelectron microscopic localization of the hormones whose production had been attributed to pancreatic islets was conducted. Glucagon and insulin were respectively localized in the typical A- and B-cells, whereas no subclasses of A-cells could be identified. With antibodies that reacted with the gastrin cells in the human gastric mucosa, it was not possible to detect gastrin in any of the islet cell types. In confirmation of recent results obtained by light microscopy, somatostatin was found in all the typical D-cells containing large, weakly electron-dense secretory granules. The human pancreatic polypeptide (HPP), a newly postulated hormone, was clearly associated with a fourth cell type, which is characterized by the presence of small secretory granules (100-150 nm.). These results suggest that each of the four cell types that are easily identifiable by ultrastructural observations is responsible for the production of a specific secretory product.
Diabetes 1977 Aug
PMID:Identification of four cell types in the human endocrine pancreas by immunoelectron microscopy. 32 32


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