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

The mechanisms controlling secretion of glucagon and other pancreatic hormones were studied in a patient affected with multihormone-secreting islet-cell tumor. Fasting glucagon levels (3,000 pg./ml.) rose to 10 ng./ml. following arginine stimulation. While oral glucose load and intravenous glucose infusion did not suppress glucagon secretion, insulin administration induced a prompt depression in glucagon levels. Glucagon, insulin, and gastrin levels were suppressed by somatostatin while calcium infusion caused a paradoxical increase. It is suggested that only some of the stimulation-inhibition mechanisms were conserved in this case of glucagon-secreting pancreatic tumor.
Diabetes 1976 May
PMID:Suppression and stimulation mechanisms controlling glucagon secretion in a case of islet-cell tumor producing glucagon, insulin, and gastrin. 0 26

Male and female virgin rats and breeder rats with naturally-occurring diabetes, hypertension and arteriosclerosis, were made severely diabetic with a single, subcutaneous injection of alloxan (10 mg/100 g b.w.), after an 18 h fast. During five months of unrelenting diabetes, some animals became obese while others became emaciated. Only the emaciated animals survived but they were blind, their adrenal glands were hemorrhagic, hypertrophied and thrombosed, thymi involuted, kidneys swollen, hearts reduced in size while testes and ovaries were atrophic. Serum CPK, SGOT and SGPT were elevated concomitant with extensive cardiovascular damage, hepatic steatosis and generalized catabolism. Circulating triglycerides and free fatty acids were markedly elevated with total cholesterol only slightly increased. BUN and serum calcium levels were also greatly elevated. Sub-normal Cmpd. B levels indicated impaired adrenal steroidogenesis. Virgin rats developed arteriosclerosis and male and female breeder rats showed exacerbation of their pre-existing aortic sclerosis as well as P.A.N. lesions in their small-sized arteries. It is believed that severe diabetes causes exacerbation of the endogenous hormonal milieu resulting from abnormal hypothalamic-pituitary-adrenal function induced by repeated breeding, which conditions the connective tissue components of the arterial wall of rats toward accelerated degenerative changes.
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PMID:Polyarteritis nodosa induced in arteriosclerotic, male and female breeder rats by chronic alloxan diabetes. 1 32

Examination of glucose kinetics, pancreatic alpha and beta cell function, plasma lipids, urinary acidification and calcium excretion has been undertaken in a patient with hereditary fructose intolerance. This case was unusual as it was associated with insulin-requiring diabetes, type IV hyperlipemia, hypercalciuria and renal calculi. He also demonstrated the previously described fructose-induced defect of urine acidification. Glucagon and C-peptide assays showed that the pancreatic alpha cells were stimulated by fructose and that the beta cells did not respond to fructose. It is not known whether the latter was due to his diabetes or to the lack of a beta cell response to this sugar. Primed 14C-glucose infusions were used for the first time to study nonsteady state glucose kinetics in man. They showed that, 24 hours after the last insulin injection and under basal conditions, the glucose concentrations increased because glucose production exceeded glucose utilization. However, after the administration of sorbitol the plasma glucose concentration decreased because glucose production decreased. After the administration of sorbitol there was no change in the metabolic clearance of glucose. This reflects the lack of a peripheral insulin effect and is consistent with the lack of any measurable C-peptide. Glucose utilization also decreased, but this decrease was less than the decrease in glucose production. Because the metabolic clearance of glucose remained unchanged, it was concluded that the change in glucose utilization was solely due to the decrease in glucose concentration. The absence of C-peptide in the plasma indicated that changes in glucose turnover were not related to any changes in endogenous plasma insulin. Furthermore, the plasma glucagon concentration increased and, hence, changes in this hormone could not account for the decrease in glucose production. Therefore, it was concluded that the sorbitol-induced decline in glucose production was due to a direct effect on hepatic metabolism.
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PMID:Studies of glucose turnover and renal function in an unusual case of hereditary fructose intolerance. 1 54

Pancreatic islets were microdissected from ob/ob mice, loaded for 2 h with 45Ca and perfused with calcium-deficient medium. Irrespective of the glucose and calcium concentrations in the loading medium, increased glucose in the perfusion medium resulted in reduced amounts of radioactivity in the perfusate. A glucose inhibition of 45Ca washout was also evident when the specific radioactivity of the islets approached that of the labeling medium, indicating that the effect was not simply due to isotopic dilution. The depression of 45Ca washout diminished after culture of the islets in a serum-free medium and it was absent in islets taken from mice homozygous for the gene diabetes. The glucose effect became less pronounced when 50 micron D-600, an inhibitor of the calcium inward transport, was added to the calcium-deficient perfusion medium and abolished in the presence of 20 mM Ca-EGTA. The inhibition of the 45Ca washout observed is not necessarily due to a direct glucose interaction with the outward calcium transport but may also result from stimulation of the uptake and intracellular trapping of the cation.
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PMID:Glucose inhibition of 45Ca efflux from pancreatic islets. 9 51

Calcium distribution in B cells of the isolated perfused rat pancreas was examined by the pyroantimonate precipitation technique in relation to the insulin secretory pattern of the perfused pancreas in response to 3 mM or 20 mM D-glucose or 20 mM D-glucose in calcium-depleted ethylene glycol tetra-acetic acid (EGTA) medium. Perfusion fixation after various time intervals from 3 to 30 min allowed appropriate relation to secretory phases. Qualitative and quantitative evaluation of the precipitation patterns revealed a significant increase in cell membrane associated percipitates after 3--5 min of perfusion with 20 mM glucose compared with the results after perfusion with 3 mM glucose. After 10--30 min of perfusion with 20 mM glucose there was an additional significant increase in precipitates located in the cytoplasm and the halos of the secretory granules. Perfusion with 20 mM glucose in calcium-deprived EGTA medium strongly reduced the number of precipitates within the B cells. The results suggest that cell membrane associated calcium may be involved in exocytosis, and by its sudden increase may trigger the first phase of insulin secretion. The calcium stores in the cytoplasm and the granules may be of importance for long-term regulation of insulin release.
Diabetes 1979 Jun
PMID:Ultracytochemical calcium distribution in B cells in relation to biphasic glucose-stimulated insulin release by the perfused rat pancreas. 10 39

The effects of intravenous administration of potassium phosphate in the treatment of diabetic ketoacidosis were studied in nine children, ages 9 9/12 to 17 10/12 yr. During phosphate infusion (20--40 meq/L of fluid), all children maintained normal serum concentrations of phosphorus. Transient hypocalcemia occurred in six and transient hypomagnesemia in five patients. One child developed carpopedal spasms refractory to intravenous infusion of calcium gluconate but responsive to intramuscular injection of magnesium sulfate. In three patients, serum levels of intact parathyroid hormone were low at the time of hypocalcemia, an observation that suggests transient hypoparathyroidism. This study indicates that the use of potassium phosphate as the sole source of potassium replacement might potentiate ketoacidosis-induced hypocalcemia through multiple mechanisms.
Diabetes Care
PMID:Hypocalcemia, hypomagnesemia, and transient hypoparathyroidism during therapy with potassium phosphate in diabetic ketoacidosis. 11 30

Retinal capillary junctions were analysed in normal and diabetic rats and in a human retina with the electron microscope. Diabetes mellitus was induced with streptozotocin. The retinae were fixed in Palade's osmium tetroxide containing sodium or calcium ions and block-stained in uranyl acetate. With Ca-fixation, no significant difference in interendothelial cleft width was detected between retinal layers or between normal and diabetic retinae. Diabetes caused a narrowing of the clefts in the Na-fixed tissue X +/- SE, n=375; Normal: 78.6 +/- 300 A; Diabetic: 57.7 +/- 2.42 A; p less than 0.001). A significant correlation was found between cleft width and the length of the tight junctions or zonulae occludentes (p less than 0.001). In the nerve fibre layer of the Na-diabetic retina, where cleft narrowing was greatest, there was an increase in length of the zonulae occludentes from 22.8 +/- 2.2% to 41.6 +/- 3.7% (p less than 0.001). Ca-fixation prevented these changes, indicating that at least some zonulae occludentes were interendothelial extraction artefacts. In the normal retina, endothelial cell membrane thickness was greater with Ca- than Na-fixation (p less than 0.001). Diabetes caused a decrease in membrane thickness of Ca-fixed tissue (p less than 0.001). The diabetic decrease in membrane thickness may explain the increased fragility and increased permeability of diabetic capillaries. Calcium binding by endothelial cell membranes is of primary importance in anticoagulation which is defective in diabetes.
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PMID:Retinal capillary junctions: ultrastructural tight junction artefacts induced by sodium ions and membrane reduction in streptozotocin diabetes. 12 16

Duodenal calcium absorption is depressed in alloxan and streptozotocin diabetic rats taking normal amounts to dietary vitamin D. Depression of absorption appears to be at least in part the result of altered metabolism of vitamin D with failure to form 1,25-dihydroxycholecalciferol (1,25-(OH)2D3), the vitamin D metabolite that acts directly on duodenum to stimulate calcium absorption. The South American plant Solanum malacoxylon causes extensive soft tissue calcification when ingested by cattle. An extract of this plant restores calcium absorption depressed by dietary strontium blockage of 1,25-(OH)2D3 formation in chicks. We gave an aqueous extract of S. malacoxylon to diabetic rats and restored duodenal calcium absorption to normal. These findings provide further evidence of the ability of a factor in the S. malacoxylon extract to mimic the actions of 1,25-(OH)2D3 on duodenal calcium transport and reinforce the hypothesis that abnormal vitamin D metabolism is an important determinant of depressed duodenal calcium absorption in diabetes.
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PMID:Depressed duodenal calcium absorption in the diabetic rat: restoration by Solanum malacoxylon. 12 46

Control and streptozotocin diabetic rats were studied at 5 and 12 days after induction of diabetes. Strontium absorption was measured by in situ perfusion of duodenum and ileum. Duodenal absorptive capacity (absorption per unit length) and absorptive specific activity (absorption per gram of dry weight mucosa) were depressed. Depression was present both at 5 days, when mucosal growth is similar in controls and diabetics, and at 12 days, when mucosal growth is 50% greater in diabetics. Effects of diabetes on ileal absorption were minimal in comparison with effects on duodenum. This depression of duodenal strontium absorption in the diabetic rat is analogous to effects of diabetes on calcium absorption and may be mediated by abnormal vitamin D metabolism.
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PMID:Effects of experimental diabetes on intestinal strontium absorption in the rat. 13 63

Control and streptozotocin-diabetic rats were studied at 5, 12, and 32 days after induction of diabetes. Magnesium absorption was measured by in situ perfusion of duodenum and ileum. At 5 days, duodenal mucosal growth is similar in controls and diabetics. At 12 days, mucosal growth is 50% greater in diabetics, and at 32 days, 100% greater. Ileal mucosal growth followed the same pattern but was half that of duodenum. Therefore, absorption data were expressed per centimeter segment length to define absorptive capacity of the segment and per gram dry weight of mucosa to define absorptive specific activity. Mean absorptive specific activity was lower in diabetics than controls at all time intervals. The difference was significant only for duodenum of diabetics at 32 days, when magnesium absorption declined to half that of controls. In contrast, absorptive capacity for both segments remained the same in both groups, attributable to the greater mucosal growth in diabetics. These findings for magnesium contrast with effects of diabetes on calcium transport: specific absorption and segment absorptive capacity are depressed in diabetics at both 5 and 11 days. Thus, although transport of magnesium and calcium usually tend to change in parallel in diabetes, transport of magnesium is depressed later and to a lesser degree than calcium, and segment transport capacity is maintained. The findings suggest differences in mechanism of regulation of magnesium and calcium transport.
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PMID:Effects of diabetes on intestinal magnesium absorption in the rat. 13 4


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