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

Experimental diabetes results in an inhibition of the glycolytic and lipogenic pathways in rat liver, while treatment of diabetic rats with T3 for four days increases the activity of a number of enzymes linked to lipogenesis. Hepatic metabolites were estimated in control (untreated), control + T3-treated, alloxan-diabetic and alloxan-diabetic + T3-treated rats. Diabetes resulted in the expected decrease in the content of fructose 2,6-bisphosphate and an increase in the content of cyclic AMP and citrate, changes consistent with an inhibition of hepatic glycolysis. Treatment of diabetic rats with T3 did not reverse these changes. There was a marked accumulation of both acetyl CoA and citrate in the diabetic rat liver, which was of even greater magnitude in diabetic and in the T3-treated group. In addition, T3 treatment significantly increased the free CoA content of liver in both normal and diabetic groups. Of the parameters measured which influence lipogenesis, including long chain acyl CoA, the energy charge and redox state of the nicotinamide nucleotides, the raised hepatic citrate content correlated most closely with the known increase in lipogenesis in diabetic rats treated with T3 for a four day period.
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PMID:Effect of thyroid hormones on the levels of metabolic intermediates in diabetic rat liver. 335 70

The relationship between the dose of intravenously administered streptozotocin (a N-nitroso derivative of glucosamine) and the diabetogenic response has been explored by use of the following indices of diabetogenic action: serum glucose, urine volume, and glycosuria, ketonuria, serum immunoreactive insulin (IRI), and pancreatic IRI content. Diabetogenic activity could be demonstrated between the doses of 25 and 100 mg/kg, all indices used showing some degree of correlation with the dose administered. Ketonuria was only seen with the largest dose, 100 mg/kg. The most striking and precise correlation was that between the dose and the pancreatic IRI content 24 hr after administration of the drug, and it is suggested that this represents a convenient test system either for both related and unrelated beta cytotoxic compounds or for screening for modifying agents or antidiabetic substances of a novel type. Ability to produce graded depletion of pancreatic IRI storage capacity led to an analysis of the relationship between pancreatic IRI content and deranged carbohydrate metabolism. Abnormal glucose tolerance and insulin response were seen when pancreatic IRI was depleted by about one-third, while fasting hyperglycemia and gross glycosuria occurred when the depletion had reached two-thirds and three-quarters, respectively. The mild yet persistent anomaly produced by the lowest effective streptozotocin dose, 25 mg/kg, exhibits characteristics resembling the state of chemical diabetes in humans and might thus warrant further study as a possible model. Finally, the loss of the diabetogenic action of streptozotocin by pretreatment with nicotinamide was confirmed and was shown to be a function of the relative doses of nicotinamide and streptozotocin and of the interval between injections.
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PMID:Diabetogenic action of streptozotocin: relationship of dose to metabolic response. 424 8

The possibility of preventive intervention in Type I or insulin-dependent diabetes mellitus (IDDM) during periods of latency and partial remission of the disease has stimulated the search for agents that interfere with the genesis of IDDM by acting on its etiology and/or by protecting the beta cell against different aggressions. Recent attempts, which have been applied mostly to animal models, but also to patients, include: antiviral therapy, immunotherapy, administration of free radical scavengers, nicotinamide and high protein diet.
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PMID:New trends in diabetes research: the search for an etiologically oriented treatment for type I diabetes mellitus. 620 Dec 23

The effect of streptozocin (STZ)-induced diabetes on the plasma membrane calcium uptake of rat liver was investigated. Plasma membrane preparations from diabetic rats showed a 2-3-fold increase in calcium uptake activity over controls 3-4 wk after the initial injections. Such an increase can be either reversed or blocked by treating the diabetic rats with exogenous insulin or administering nicotinamide 15 min before and 3 h after the STZ injection, respectively. The activity of 5'-nucleotidase and the [3H]ouabain binding to the plasma membranes were similar in samples from both the control and diabetic rats. These findings made it unlikely that preferential enrichment of plasma membranes or increased proportion of inside-out vesicles was the cause of the enhanced calcium uptake activity in membranes from diabetic animals. In addition, the effect of diabetes on the calcium uptake activity did not diminish even when the assay was performed in the presence of 2.5 microM ruthenium red, an inhibitor of calcium uptake by mitochondria, or when oxalate was omitted from the assay, suggesting that the effect was specifically on the plasma membrane pump. The enhanced calcium uptake activity was a result of an increase in the Vmax (58.8 versus 113.1 pmol calcium/mg protein/min for control and diabetic rats, respectively). No significant change in Km for calcium was detected.
Diabetes 1984 Nov
PMID:The effect of streptozocin-induced diabetes on the plasma membrane calcium uptake activity of rat liver. 620 83

This experiment was undertaken to explore a novel method of therapy for insulin-dependent diabetes mellitus (IDDM), using nonobese diabetic (NOD) mice that had symptoms and histologic changes similar to those of human IDDM patients. We examined preventive and therapeutic effects of large-dose nicotinamide administration on diabetes in NOD mice. Eighteen young female NOD mice without glycosuria were randomly divided into two groups; nine received subcutaneous nicotinamide (0.5 mg/g body wt) injections every day and the other nine were maintained as a control group and not injected. After 40 days, all of the mice given nicotinamide showed almost normal glucose tolerance and only mild insulitis on histologic study. On the other hand, marked glycosuria and severe insulitis were observed in six of the nine mice not injected. Four of six NOD mice given nicotinamide from the day of the first occurrence of marked glycosuria displayed a disappearance of glycosuria and an improvement in glucose tolerance during the therapy; however, urine sugar became negative in only one of six mice that received nicotinamide from 1 to 2 wk after the onset of marked glycosuria. These results indicate that nicotinamide has preventive and therapeutic effects on diabetes in NOD mice, and suggest the reversibility of B-cell damage, at least at a very early stage of IDDM.
Diabetes 1982 Sep
PMID:Preventive and therapeutic effects of large-dose nicotinamide injections on diabetes associated with insulitis. An observation in nonobese diabetic (NOD) mice. 621 22

Comparisons were made of the dose-response and time-course characteristics of nicotinamide (NIC) and its metabolite, N1-methylnicotinamide (MNIC), protection from alloxan-induced diabetes in mice. A significant reduction in the permanent hyperglycemia caused by alloxan (50 mg/kg, iv) was observed when NIC or MNIC was given iv at a dose of 800 mg/kg 2 hr before alloxan. Complete protection was provided by pretreatment with 1200 mg/kg of either agent. There was a linear increase in 2-hr serum levels of NIC or MNIC after increasing doses of each protective agent. Protection after a 1200 mg/kg dose of NIC was of a shorter duration (6 hr) than after a corresponding dose of MNIC (greater than 24 hr). This longer protective action of the metabolite was accompanied by correspondingly higher serum levels of MNIC when compared to levels of NIC after an identical dose. No protective effects of NIC or MNIC were apparent when the agents were added to isolated mouse pancreatic islets prior to alloxan exposure in vitro. The results indicate that both NIC and its metabolite, when given in high doses before alloxan, are capable of protecting mice from alloxan diabetes. The protective action of NIC and MNIC appears to be an indirect one because the agents were ineffective as protectants in an in vitro system.
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PMID:Characteristics of nicotinamide and N1-methylnicotinamide protection from alloxan diabetes in mice. 622 23

Diabetic mouse serum was found to be toxic to F-10 melanoma cells in vitro. However, when F-10 cells were injected intravenously into streptozotocin-induced diabetic mice there was a significant increase in the number of lung tumors. Contrarily, when streptozotocin was injected after F-10 cells there was a 5-fold decrease in lung metastases. Reversal of the diabetes in these mice by nicotinamide or insulin injection did not increase the lung metastases. Solid tumors (resulting from the subcutaneous injection of F-10 cells) grew at similar rates in both control and diabetic mice. Streptozotocin injected after F-10 cells resulted in a 6 day delay in the appearance of solid tumors. Triglycerides, the toxic factors in vitro, were elevated to similar extents in both tumor-bearing control and diabetic mice. Most of the differences in tumor growth between control and streptozotocin injected mice were attributable to the antitumor activity of streptozotocin, rather than the diabetic state.
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PMID:Differential effects of streptozotocin and streptozotocin-induced diabetes mellitus on tumor metastases and growth in mice. 623 Sep 83

Nicotinamide, a poly(ADP-ribose)synthetase inhibitor, protected NMRI mice against alloxan-induced hyperglycemia when given 10 min before, but not 10 min after, the injection of the drug. Pretreatment in vivo with nicotinamide induced hyperglycemia at the time of alloxan injection, and this could account for the protective action of nicotinamide against alloxan diabetes. Exposure of islets to alloxan (2 mM) in vitro caused a marked inhibition of both glucose-stimulated proinsulin biosynthesis and insulin release, and this was not affected by the action of nicotinamide. Alloxan-impaired islet glucose oxidation was partly restored by nicotinamide. The decreased islet content of NADH plus NAD, which was observed after alloxan treatment, could be prevented by nicotinamide. Glucose-stimulated islet oxygen uptake was abolished after treatment with alloxan, and nicotinamide had no protective effect in this process. Leucine (10 mM) plus glutamine (10 mM), however, were still able to evoke an islet respiratory response after alloxan exposure. Alloxan caused an immediate increase in the islet efflux of radiolabeled nucleotides, which was followed after about 5 min by a further increase. This latter increase of the radio efflux was inhibited by the addition of nicotinamide. The inability of nicotinamide to prevent the alloxan-induced impairment of proinsulin biosynthesis, insulin release, and oxygen uptake, together with the failure of nicotinamide to prevent the development of diabetes when given after alloxan, does not support a current hypothesis that the major cytotoxic effect of alloxan is primarily due to DNA damage. The present data suggest that organelles other than the nuclei, e.g., the mitochondria or the plasma membrane, are the primary sites of B-cell injury by alloxan.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1984 Oct
PMID:Nicotinamide does not protect islet B-cell metabolism against alloxan toxicity. 623 9

Oral ingestion of a new rat poison that antagonizes nicotinamide metabolism, N-3-pyridylmethyl-N'-p-nitrophenyl urea (PNU, Vacor), is known to cause diabetes mellitus. I describe neurologic complications of PNU ingestion in 12 patients 19 to 50 years of age who swallowed between 0.39 and 7.02 g of PNU. One died within a day, and five died of chronic complications 40 to 182 days after taking the poison. Apart from the acute hyperglycemic ketoacidosis, the clinical presentation was variable, but orthostatic hypotension, gastrointestinal hypomotility, peripheral neuropathy, and encephalopathy were typical. The peripheral, autonomic, and central-nervous dysfunction could develop either acutely or other several days. It is possible that nicotinamide, given parenterally within minutes, prevents toxicity, but the cases discussed in this paper indicate that the neurologic deficits may progress despite later nicotinamide administration. Neurologic improvement took many months. Full recovery was uncommon, and the orthostatic, hypotension tended to persist.
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PMID:The neurotoxicity of the rat poison vacor. A clinical study of 12 cases. 624 67

Young male Holtzman rats injected with nicotinamide and streptozotocin develop grossly visible tumors of pancreatic islet tissue. Using an i.v. glucose tolerance test, some tumor-bearing animals exhibited a vigorous (or fast) response to glucose loading (Diabetic Index = 0.47), whereas others showed a subdiabetic (or slow) response (Diabetic Index = 2.34). In vitro perifusion studies demonstrate that tumor pieces from both groups of rats released immunoreactive insulin (IRI) in response to glucose; tumors from fast responding rats showed a rapid monophasic release of IRI (i.e., rapid transient release with little secondary phase), while tumors from slow responders released IRI in a biphasic pattern resembling that of normal islets. A population of large islet masses (or microscopic tumors), isolated from drug-treated rats by collagenase digestion of the pancreas of tumor-containing rats, exhibited glucose-stimulated IRI release that resembled the pattern of the tumor from the same animal. Isolated islets of Langerhans of ordinary size from the pancreas of tumor-bearing rats, on the other hand, usually exhibited a normal (biphasic) IRI release pattern in response to glucose. Analysis by gel filtration suggests that the predominant form of IRI released from perifused tumor preparations, under either basal or glucose-stimulated conditions, eluted at a rate corresponding to rat insulin.
Diabetes 1981 Apr
PMID:Insulin release in vitro from islet tissues and adenomas of rats treated with nicotinamide and streptozotocin. The effects of glucose. 625 6


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