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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nerve ischemia/hypoxia has been linked to the pathogenesis of diabetic complications. Red blood cell 2,3-diphosphoglycerate is an important regulator of peripheral tissue oxygenation; however, the relationship between 2,3-diphosphoglycerate concentration and diabetic complications has not been studied in detail. This investigation focused on the relationship between red blood cell 2,3-diphosphoglycerate and diabetic neuropathy, by measuring motor nerve conduction velocity and sciatic nerve blood flow in streptozotocin-induced diabetic rats. The effect of treatment with niceritrol, a nicotinic acid derivative that acts as a vasodilator and reduces serum lipid concentrations, on 2,3-diphosphoglycerate concentration and diabetic neuropathy was also examined. Untreated diabetic rats had significantly lower concentrations of red blood cell 2,3-diphosphoglycerate, higher concentrations of serum total cholesterol and triglyceride, as well as reduced motor nerve conduction velocity and sciatic nerve blood flow, compared to untreated normal rats. Niceritrol prevented these abnormalities without correcting hyperglycemia in diabetic rats, but had no effect on these parameters in normal rats. Red blood cell 2,3-diphosphoglycerate concentration and motor nerve conduction velocity showed a positive correlation with sciatic nerve blood flow and 2,3-diphosphoglycerate, respectively. These observations suggest that ischemia/hypoxia plays an important role in the development of diabetic neuropathy, and that niceritrol has a therapeutic effect on this condition by improving endoneurial ischemia/hypoxia.
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PMID:Niceritrol prevents the decrease in red blood cell 2,3-diphosphoglycerate and neuropathy in streptozotocin-induced diabetic rats. 754 76

To address the problem of the pathogenesis of diabetic neuropathy, rats were made diabetic by alloxan administration, and sciatic nerves were sampled for electrolyte and water content and levels of selected carbohydrates and intermediates in energy metabolism at 3, 6, and 26 weeks. Significant increases were seen in the nerve content of glucose, sorbitol, and fructose. Decreases of myo-inositol were not statistically significant. Glucose-6-phosphate was increased at all times; fructose-1,6-bisphosphate was elevated at 6 and 26 weeks. Nerve ATP and phosphocreatine levels were both increased concomitantly, as was the energy charge. Nerve lactate levels increased only at 26 weeks when plasma lactate levels were also high. Plasma ketone bodies were elevated throughout the 26-week experimental interval. It is postulated that ketone bodies were being used as alternative metabolic fuels in diabetic nerve, thereby causing inhibition of pyruvate oxidation and increased aerobic production of lactate. Increased plasma ketone body levels could also inhibit hepatic lactate uptake. There was no other evidence for hypoxia/ischemia. Lactate:pyruvate ratios did not differ from control values at any time in these ketotic hypoinsulinemic animals. Five major hypotheses have been proposed to explain the pathogenesis of diabetic neuropathy: 1) hypoxia/ischemia, 2) hyperglycemic pseudohypoxia, 3) myo-inositol deficiency, 4) fructose and polyol accumulation and osmotic disequilibrium, and 5) nonenzymatic glycation of macromolecules by fructose and glucose. The data obtained in this study seem to fit best with hypotheses 4 and perhaps 5.
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PMID:Effects of acute, subacute, and chronic diabetes on carbohydrate and energy metabolism in rat sciatic nerve. Relation to mechanisms of peripheral neuropathy. 785 40

During the past 3 years six episodes of ischemic monomelic neuropathy (IMN) have been identified in five patients as a complication of upper extremity dialysis grafts. All patients had long-standing insulin-dependent diabetes, peripheral neuropathy, and brachial artery graft origins, whereas 60% had peripheral vascular disease. Five episodes occurred immediately after graft placement, whereas one was due to a graft-related thromboembolus. Diagnostic delay was common with initial findings attributed to anesthesia, positioning, or surgical trauma. Electrophysiologic studies showed underlying diabetic neuropathy with severe multifocal neuropathy distal to the grafts. Digital pressure indices were reduced but there was no critical ischemia. In three cases ischemia was completely corrected with improvement in one. One patient had proximal balloon angioplasty with no improvement and of the two untreated patients, one improved slightly. Ischemic monomelic neuropathy is a rare but disabling complication of dialysis access in diabetic uremic patients. Its occurrence is unpredictable and diagnostic delay is common. Correction of ischemia is indicated but usually does not improve the neuropathy. Prevention requires further research to more accurately characterize the patients at risk.
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PMID:Ischemic monomelic neuropathy: an under-recognized complication of hemodialysis access. 786 97

Metabolic and vascular factors have been invoked in the pathogenesis of diabetic neuropathy but their interrelationships are poorly understood. Both aldose reductase inhibitors and vasodilators improve nerve conduction velocity, blood flow, and (Na+,K+)-ATPase activity in the streptozotocin diabetic rat, implying a metabolic-vascular interaction. NADPH is an obligate cofactor for both aldose reductase and nitric oxide synthase such that activation of aldose reductase by hyperglycemia could limit nitric oxide synthesis by cofactor competition, producing vasoconstriction, ischemia, and slowing of nerve conduction. In accordance with this construct, N-nitro-L-arginine methyl ester, a competitive inhibitor of nitric oxide synthase reversed the increased nerve conduction velocity afforded by aldose reductase inhibitor treatment in the acutely diabetic rat without affecting the attendant correction of nerve sorbitol and myo-inositol. With prolonged administration, N-nitro-L-arginine methyl ester fully reproduced the nerve conduction slowing and (Na+,K+)-ATPase impairment characteristic of diabetes. Thus the aldose reductase-inhibitor-sensitive component of conduction slowing and the reduced (Na+,K+)-ATPase activity in the diabetic rat may reflect in part impaired nitric oxide activity, thus comprising a dual metabolic-ischemic pathogenesis.
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PMID:The linked roles of nitric oxide, aldose reductase and, (Na+,K+)-ATPase in the slowing of nerve conduction in the streptozotocin diabetic rat. 804 Mar 41

In 31 patients with coronary artery disease (autonomic neuropathy, n = 11; diabetes without neuropathy, n = 10; silent myocardial ischemia without diabetes, n = 10) difference in somatic pain threshold and plethysmographically determined reactive hyperemia induced by forearm skeletal muscle ischemia was investigated. There was no difference in reactive hyperemia after passive maximum forearm ischemia in the three groups indicating identical vascular reactivity. After symptom-limited ischemic work however, reactive hyperemia was significantly higher in patients with silent myocardial ischemia as compared to diabetic patients. Exercise time was longer in patients with silent myocardial ischemia (153 +/- 51 s) as in patients with diabetic neuropathy (139 +/- 45 s) and diabetics without neuropathy (120 +/- 45 s). Pain as a cause of termination of symptom-limited ischemic forearm exercise occurred less frequently in patients with diabetic neuropathy (2/11) and patients with silent myocardial ischemia (3/10) as compared to patients with diabetes without neuropathy (9/10). In conclusion, patients with silent myocardial ischemia have a higher ischemic tolerance in the working forearm as compared to diabetic patients with and without neuropathy. There is a quantitative difference in ischemic tolerance between patients with silent myocardial ischemia and patients with diabetic neuropathy.
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PMID:Somatic pain threshold and reactive hyperemia in autonomic diabetic neuropathy and silent myocardial ischemia. 811 16

Besides distal symmetrical sensory polyneuropathy (DSSP), middle-aged diabetic patients may present with focal or multifocal neuropathies, including proximal neuropathy of the lower limbs, the pathophysiological features of which are uncertain. We studied 10 non-insulin-dependent diabetic patients, 45 to 72 years of age, who developed a painful proximal neuropathy of the lower limbs for which other causes of neuropathy were carefully excluded. The proximal neuropathy was asymmetrical in all patients, sensory in 4, motor and sensory in the others. Signs of DSSP were present in all. A sample of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, was taken by biopsy and examined by light and electron microscopy. Examination of the nerve specimens revealed ischemic nerve lesions in 3 patients. Nerve ischemia was associated with vasculitis and inflammatory infiltration in 2 of them. In the other patients the lesions of the cutaneous nerve of the thigh included a varying incidence of axonal and demyelinative lesions similar to those observed in DSSP, with mild inflammatory infiltration in 4 of them. The density of myelinated and of unmyelinated was variably decreased. This study shows that axonal and demyelinative lesions similar to those found in diabetic DSSP are present in proximal nerves in mild forms of proximal diabetic neuropathy; while nerve ischemia, inflammatory infiltration, and vasculitis are encountered in the most severe forms of proximal diabetic neuropathy.
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PMID:Nerve biopsy findings in different patterns of proximal diabetic neuropathy. 817 2

The differences between diabetic and nondiabetic patients with silent myocardial ischemia were investigated. Based on the results of previous exercise testing, a total of 110 patients (15 diabetic and 95 nondiabetic) with exercise-induced myocardial ischemia were divided into the following 3 groups: 15 diabetics with silent myocardial ischemia, 49 nondiabetics with silent myocardial ischemia, and 46 nondiabetics with anginal symptoms. All patients underwent treadmill exercise testing and 24-hour ambulatory electrocardiographic recording. Before and during exercise, blood samples from the antecubital vein were obtained to determine the plasma beta-endorphin levels, and the pain threshold of each patient was measured with the electrical skin stimulation test. Furthermore, with regard to the ambulatory electrocardiographic recording, the mean of the SDs of all normal sinus RR intervals during successive 5-minute recording periods over 24 hours was analyzed and considered as an index of the autonomic function. The plasma beta-endorphin level during exercise was significantly greater in nondiabetic patients with silent ischemia than in diabetic ones. The SD mean was significantly less in the diabetic group than in the 2 nondiabetic ones. The findings suggest that the role of beta endorphin in diabetic patients with silent myocardial ischemia may be less significant than in nondiabetic ones; therefore, a diabetic neuropathy that affects the autonomic pain fibers that innervate the heart may be involved in the mechanism of silent myocardial ischemia in diabetics.
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PMID:Usefulness of plasma beta-endorphin level, pain threshold and autonomic function in assessing silent myocardial ischemia in patients with and without diabetes mellitus. 832 73

Retrograde venous pulse therapy (RVP) allows faster healing of the infection, shortening of hospitalization time, and recovering of the chronic ischemia. RVP als has a dramatic effect on diabetic foot by passing the functional disorder of the microcirculation produced by diabetic neuropathy and micro-angiopathy, with important reduction of amputation rates in these patients. We credit these results to the very high concentration of Buflomedil provided by RVP in the target tissues, which allows the penetration and impregnation of other active substances (7).
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PMID:[Pioneer experience with buflomedil in the form of retrograde venous pulse therapy for treatment of ischemia and severe extremity infections]. 837 75

In this paper we discuss the possible role of disturbed neuronal calcium homeostasis in brain aging and diabetic neuropathy. Disturbances in the homeostasis of cytosolic calcium concentration have been implicated in the pathogenesis of various acute and chronic neurodegenerative disorders and in brain aging. Obviously, these disorders do not all share the same pathogenetic mechanisms. However, a number of the pathogenetic mechanisms involved have in common that they may ultimately cause loss of calcium homeostasis, leading to neuronal damage. By identifying the possible role of calcium, treatment strategies can be developed that may be effective in a variety of neurodegenerative disorders, despite differences in their pathogenesis. Our aim is to explore some of the similarities that exist between a number of processes that have been implicated in the pathogenesis of brain aging and diabetic neuropathy, including ischemia, oxidative stress and non-enzymatic protein glycosylation. Each of these factors might impair neuronal calcium homeostasis, and ultimately lead to neurodegenerative changes. By discussing the putative role of these specific factors in two apparently dissimilar disorders, such as brain aging and diabetic neuropathy, we obviously do not intend to suggest that their pathogenesis is one and the same. Instead, by examining the relative role of these factors in two different types of neurodegenerative disorders we would like to emphasize the importance of disturbances in cellular calcium homeostasis as a final common pathway in neuronal damage resulting from various noxious events.
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PMID:The calcium hypothesis of brain aging and neurodegenerative disorders: significance in diabetic neuropathy. 876 25

An abnormal axonal membrane conductance might contribute to human diabetic neuropathy. To test this idea, we have compared the threshold changes produced by long-lasting (100-200 ms) de- and hyperpolarizing currents applied to median motor and sensory axons at the wrist in 63 diabetic patients with those from 50 normal controls and 27 amyotrophic lateral sclerosis (ALS) patients. Averages of the threshold electrotonus plots for motor and sensory axons of diabetic patients showed more subexcitability during, and slower recovery following, the application of hyperpolarizing currents. Such alterations have been previously found in isolated rat nerves after inhibition of axonal inward rectification by means of cesium ions. The abnormalities in diabetics were positively correlated with the age of patients and the presence of neuropathy. Threshold electrotonus seen in diabetes differed strongly from the effects of acute ischemia and were unlike changes recorded in ALS. The data indicate that an abnormal inward rectification of peripheral axons is associated with diabetic neuropathy. A better understanding of the neurobiology of this conductance might provide information about the pathophysiology of this disease.
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PMID:Abnormal axonal inward rectification in diabetic neuropathy. 880 52


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