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

The ability of aldose reductase inhibitors to prevent the decline in neural Na+,K(+)-ATPase activity in diabetic rats has not been confirmed by all laboratories. In this study, the efficacy of two structurally different aldose reductase inhibitors was evaluated under different experimental conditions. Na+,K(+)-ATPase activity was measured in sciatic nerves from streptozocin-induced diabetic rats fed normal rodent chow or a chow supplemented with 68% sucrose. Nerve homogenates from chow-fed rats were prepared with a Dounce tissue grinder, whereas homogenates from the sucrose-fed rats were prepared with an Ultra-Turrax disperser. In the chow-fed rats, 4 weeks of untreated diabetes resulted in an increase in neural sorbitol and fructose, a decrease in myoinositol, and a 54% decline in Na+,K(+)-ATPase activity. Sorbinil administration (20 mg/kg/day) completely prevented the rise in sorbitol and fructose and the depletion of myoinositol, but did not prevent the decline in Na+,K(+)-ATPase activity. In diabetic rats fed the sucrose diet for 4, 6, and 8 weeks, the neural sorbitol and fructose levels were elevated, the myoinositol concentration declined, and the Na+,K(+)-ATPase activity was 26 to 28% below the control. Prevention or intervention treatment with sorbinil (20 mg/kg/day) or tolrestat (50 mg/kg/day) for 4 to 6 weeks prevented the alterations in sorbitol, fructose, and myoinositol, and also prevented the decline in Na+,K(+)-ATPase activity. In conclusion, prevention and intervention therapy with aldose reductase inhibitors prevented the decline in Na+,K(+)-ATPase in sciatic nerves of sucrose-fed streptozocin-diabetic rats that were homogenized with an Ultra-Turrax disperser, but not in sciatic nerves from streptozocin-diabetic rats fed normal rodent chow that were homogenized with a Dounce tissue grinder. These findings indicate that the assessment of aldose reductase inhibitor efficacy is dramatically affected by the type of nerve preparation assayed and/or the diet.
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PMID:Adenosine triphosphatase activity in sciatic nerve tissue of streptozocin-induced diabetic rats with and without high dietary sucrose: effect of aldose reductase inhibitors. 185 65

The gut may be a site of early diabetic neuropathy in humans and rats. The latter may provide appropriate models of these conditions. Therefore, cholinergic function was examined in two gut smooth muscle preparations from control, 30-day, and 6-month streptozotocin-diabetic and similarly diabetic rats that had received continuous treatment with an aldose reductase inhibitor, ponalrestat. Responses of terminal ileum longitudinal muscle to transmural nerve stimulation were depressed in preparations from untreated 30-day diabetic animals. Responses to exogenous acetylcholine were also depressed, by at least the same extent, in preparations from both 30-day and 6-month diabetic groups. Ponalrestat treatment prevented both changes in the 30-day study but did not prevent a depression of responses to acetylcholine in the 6-month study. Neither diabetes nor ponalrestat affected responses of esophageal muscularis mucosa to electrical stimulation or to exogenous acetylcholine. These observations suggest a change in the smooth muscle and/or noncholinergic innervation rather than in the cholinergic nerves of the ileal preparation. Cholinergic function in the ileum did not, therefore, seem to be an appropriate model of diabetic neuropathy.
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PMID:Effects of diabetes on cholinergic transmission in two rat gut preparations. 189 95

Blindness in diabetics is largely due to retinopathy and/or cataract. Hyperglycaemia and the duration of diabetes are major risk factors for the development of cataract and retinopathy. This review details some of the reactions of glucose that are relevant to the development of complications, and follows the elucidation of monosaccharide autoxidation and its relevance to the aldose reductase reaction and its determination. Inhibitors of this 'aldose reductase' reaction are shown to have a number of effects which may be of importance to their action in vivo. The pharmacological implications of chemotherapy for diabetics with complications are briefly discussed.
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PMID:Aldose reductase inhibitors and cataract. 190

Increased flux through the polyol pathway mediated by the enzyme aldose reductase may be associated with the development of diabetic neuropathy. Fifty-four diabetic patients (median age 56 yr, range 25-65 yr) with chronic neuropathic symptoms were randomly allocated to placebo or aldose reductase inhibition (300 or 600 mg ponalrestat ICI 128436) groups for 24 wk. Patients with vibration perception thresholds (VPTs) greater than 35 V at the great toe or thermal difference thresholds (TTs) greater than 10 degrees C on the dorsum of the foot were excluded from the trial. No significant changes were observed in symptoms of pain, numbness, or paresthesia between ponalrestat and placebo groups, and there were no improvements in VPT or TT at several sites. Posterior tibial nerve conduction velocity changed from 35.3 +/- 4.9 m/s at baseline to 33.4 +/- 4.0 m/s at 24 wk (NS) with placebo compared with 37.6 +/- 5.6 vs. 37.2 +/- 8.7 m/s (NS) with 300 mg ponalrestat and 34.5 +/- 6.1 vs. 36.2 +/- 6.8 m/s (NS) with 600 mg ponalrestat. Further studies are indicated with intervention at an earlier stage in the evolution of neuropathy and for longer periods.
Diabetes 1991 Jan
PMID:Clinical and neurophysiological studies of aldose reductase inhibitor ponalrestat in chronic symptomatic diabetic peripheral neuropathy. 190 8

There is evidence to suggest that hyperglycemia is required for the development of the microvascular complications of diabetes. However, the precise mechanism by which hyperglycemia might cause diabetic complications is not completely clear. One possibility is the increased activity of the polyol pathway. Capillary basement membrane thickness is a hallmark histological finding in diabetic microangiopathy. Previous studies in experimental models of diabetes have related the polyol pathway with the thickness of basement membrane in retinal capillaries. To study the effect of aldose reductase inhibition with ponalrestat on the width of the skeletal muscle capillary basement membrane in subjects with diabetes, we measured the capillary basement membrane width in 55 subjects with diabetes in a double masked, placebo controlled randomized trial over a period of 18 months. Twenty-nine patients received ponalrestat (two 300 mg tablets daily) and twenty-six received placebo tablets. The age, sex distribution, type and duration of diabetes were similar in both groups. The glycosylated hemoglobin remained at a constant level throughout the study in both groups. The baseline capillary basement membrane width of the ponalrestat group was 3134 +/- 146 A, it was 3074 +/- 226 A at month 12 and 2548 +/- 182 A at month 18 (P less than 0.001 vs baseline value). The placebo group also had a significant reduction in the width of the capillary basement membrane, from a baseline value of 3026 +/- 147 A to 2818 +/- 144 A at month 12 and 2618 +/- 156 A at month 18 (P less than 0.001 vs baseline value). There was no statistical difference in the capillary basement membrane width between the two groups at any time point.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes Res Clin Pract 1991 Feb
PMID:The effect of aldose reductase inhibition with ponalrestat on the width of the capillary basement membrane in diabetes mellitus. 190 10

Hyperglycemia causes enhanced glucose metabolism by the polyol pathway in tissues not requiring insulin for glucose uptake. It has been suggested that the high level of aldose reductase activity may cause functional and structural abnormalities in diabetes and may be involved in the development of late complications. To elucidate the effect of an aldose reductase inhibitor (ponalrestat) on kidney function in uncomplicated insulin-dependent diabetes mellitus (IDDM), 20 normoalbuminuric IDDM patients were randomized to follow either 6 mo of treatment with ponalrestat (n = 11, mean +/- SD age 30 +/- 8 yr, diabetes duration 10 +/- 6 yr) or 6 mo of placebo (age 33 +/- 7 yr, diabetes duration 12 +/- 6 yr). The glomerular filtration rate (clearance of [125I]iothalamate) was significantly reduced from 140 +/- 18 to 129 +/- 10 ml.min-1.1.73 m-2, 2P = 0.02) in the ponalrestat-treated patients, whereas no change was seen after placebo (142 +/- 12 vs. 141 +/- 12 ml.min-1.1.73 m-2). The renal plasma flow (clearance of 131I-labeled hippuran), urinary albumin excretion rate (radioimmunoassay), fractional albumin clearance, and renal vascular resistance were unchanged in both groups. HbA1c showed a modest increase during ponalrestat (7.9 +/- 1.8 vs. 8.7 +/- 1.5%, 2P = 0.01) but was unchanged during placebo. No side effects of ponalrestat were observed. Thus, inhibition of aldose reductase may reduce the characteristic hyperfiltration in uncomplicated IDDM.
Diabetes 1991 May
PMID:Reduction of glomerular hyperfiltration in normoalbuminuric IDDM patients by 6 mo of aldose reductase inhibition. 190 26

To examine the association between renal hemodynamic abnormalities and the development of diabetic kidney disease, glomerular filtration rate (GFR) and renal plasma flow (RPF) have been determined in dogs with alloxan-induced diabetes or experimental galactosemia of 1 to 5 years duration. GFR and RPF were significantly greater than normal in insulin-deficient diabetic dogs. GFR was also significantly greater than normal in the galactosemic animals, and RPF tended to be elevated even though GFR and RPF were measured at time of day when plasma galactose is no longer elevated. GFR and effective RPF (eRPF) were found to increase in normal animals upon acute elevation of blood galactose or glucose concentration. Thus, GFR is supranormal in experimental galactosemia, as well as in diabetes, although galactosemia has been shown not to cause nephromegaly, mesangial expansion, or glomerular obliteration, which are typical of diabetes. Administration of an aldose reductase inhibitor (Sorbinil) at dosages sufficient to significantly reduce erythrocyte polyol concentration did not significantly influence GFR or RPF in diabetic or galactosemic dogs.
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PMID:Renal hemodynamics in experimentally galactosemic dogs and diabetic dogs. 190 44

This study examines whether an aldose reductase inhibitor (statil, ICI) can enhance neutrophil oxidative killing by diabetic neutrophils. We have examined a radiometric assay of phagocytosis and killing of Candida albicans by neutrophils from 20 controls and 20 subjects with insulin-dependent diabetes under various in vitro glucose concentrations. Glucose was present at 5, 10 and 20 mM in the presence and absence of statil (11 microM). Phagocytosis was unaffected by raised glucose levels in controls and in diabetic subjects. Killing by the diabetic cells was inhibited by increasing concentrations of glucose, killing was 18.9 +/- 2.0, 16.9 +/- 2.4 and 14.8 +/- 2.0% (mean +/- s.e.m.) at 5, 10 and 20 mM glucose, respectively (P less than 0.05). With the addition of statil under the same conditions killing improved to 19.3 +/- 2.0, 23.2 +/- 2.2 and 23.6 +/- 2.4 (P less than 0.01), these values were similar to the controls (P greater than 0.01). We conclude therefore that aldose reductase inhibition restores oxidative killing to normal.
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PMID:The role of aldose reductase inhibition in diabetic neutrophil phagocytosis and killing. 190 27

Although most investigators now agree that chronic hyperglycemia is the basis for diabetic retinopathy, this has not been proven definitively. Even if chronic hyperglycemia is the initial common pathway leading to retinopathy and other complications of diabetes, it appears to act by different mechanisms in different tissues. The enzyme, aldose reductase, may play a major role in the development of diabetic retinopathy, but contradictory evidence exists. At the present time, results of the only study of aldose reductase inhibition and diabetic retinopathy reported in humans were negative. Another mechanism worthy of consideration is nonenzymatic glycation (glycosylation) of proteins, but there is no direct evidence of a causal role in diabetic retinopathy. Several growth factors have been identified in the retina that may promote neovascularization, and at least two inhibitors may prevent the process. There is evidence to support a role for basic and, perhaps, acidic fibroblast growth factors in retinal vasoproliferation. Transforming growth-factor beta, a peptide produced by capillary pericytes and smooth muscle cells and activated by the interaction of these cells with vascular endothelial cells, appears to be an important inhibitor of neovascularization, as is the vascular basement membrane.
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PMID:On the pathogenesis of diabetic retinopathy. A 1990 update. 190 95

The effect of two structurally unrelated aldose reductase inhibitors, sorbinil and ponalrestat, on glomerular prostaglandin production and urinary albumin excretion was investigated in rats with diabetes induced by streptozotocin. It was found that both aldose reductase inhibitors, when administered from the time of induction of the diabetes, significantly decreased the raised urinary albumin excretion in the diabetic rats, although it remained elevated compared with non-diabetic rats. Glomerular prostaglandin E and 6-keto-prostaglandin F1 alpha production was significantly increased in glomeruli obtained from the diabetic rats. Inhibition of aldose reductase caused a reduction in the raised glomerular prostaglandin production, although this remained above that observed in the non-diabetic rats. Subsequent experiments were performed to determine whether the effects of the aldose reductase inhibitors could be explained by effects on glomerular filtration rate. It was found that ponalrestat, at a dose which markedly reduced urinary albumin excretion, did not significantly affect glomerular filtration rate in non-diabetic rats, rats with untreated streptozotocin-induced diabetes and rats with diabetes partially treated with low dose insulin. Glomerular sorbitol concentrations were significantly elevated in untreated diabetic rats as early as two weeks after the induction of diabetes. It is concluded that the administration of aldose reductase inhibitors from the time of induction of diabetes significantly reduces glomerular prostaglandin production and urinary albumin excretion. The latter effect is not due to an effect on glomerular filtration rate. Increased polyol pathway activity may account in part for the increased glomerular prostaglandin production and urinary albumin excretion in early experimental diabetes.
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PMID:The effect of aldose reductase inhibitors on glomerular prostaglandin production and urinary albumin excretion in experimental diabetes mellitus. 190 23


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