Autoantibodies to ganglionic acetylcholine receptors in autoimmune autonomic neuropathies.
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BACKGROUND: Idiopathic autonomic neuropathy is a severe, subacute disorder with a presumed autoimmune basis. It is indistinguishable from the subacute autonomic neuropathy that may accompany lung cancer or other tumors. Autoantibodies specific for nicotinic acetylcholine receptors in the autonomic ganglia are potentially pathogenic and may serve as serologic markers of various forms of autoimmune autonomic neuropathy. METHODS: We tested serum from 157 patients with a variety of types of dysautonomia. Immunoprecipitation assays with iodine-125-labeled epibatidine and solubilized human neuroblastoma acetylcholine receptors were used to detect autoantibodies that bound to or blocked ganglionic receptors. RESULTS: Ganglionic-receptor-binding antibodies were found in 19 of 46 patients with idiopathic or paraneoplastic autonomic neuropathy (41 percent), in 6 of 67 patients with postural tachycardia syndrome, idiopathic gastrointestinal dysmotility, or diabetic autonomic neuropathy (9 percent), and in none of 44 patients with other autonomic disorders. High levels of the binding antibodies correlated with more severe autonomic dysfunction (including the presence of tonic pupils). Levels of these antibodies decreased in patients who had clinical improvement. All seven patients with ganglionic-receptor-blocking antibodies had ganglionic-receptor-binding antibodies and had idiopathic or paraneoplastic autonomic neuropathy. CONCLUSIONS: Seropositivity for antibodies that bind to or block ganglionic acetylcholine receptors identifies patients with various forms of autoimmune autonomic neuropathy and distinguishes these disorders from other types of dysautonomia. The positive correlation between high levels of ganglionic-receptor antibodies and the severity of autonomic dysfunction suggests that the antibodies have a pathogenic role in these types of neuropathy. (+info)
Long term studies of pancreas transplantation in experimental diabetes mellitus.
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Alloxan diabetes was induced in inbred rats that then were divided into four groups consisting of unoperated diabetic controls, sham-operated diabetic controls, rats given pancreaticoduodenal isografts, and rats given duct-ligated pancreas isografts. The animals were studied for from 18 months (controls) to two years (transplants) and the following important results were obtained: 1) In striking contrast to the diabetic controls, pancreas transplants of both types produced immediate and permanent relief of hyperglycemia, immediate and lasting elevation of serum insulin levels, a normal weight and growth curve, and good health for two years. Removal of the graft was followed by recurrence of severe diabetes. 2) Pancreas transplants of both types prevented the widespread and severe renal, ophthalmic and neural lesions of diabetes that were found in the diabetic controls. 3) The duct-ligated pancreas graft and pancreaticoduodenal transplant were equally effective in controlling diabetes. Ligation of the pancreatic duct was not followed by significant morphologic or clinical evidence of pancreatitis or by loss of endocrine function. 4) Portal venous drainage of the pancreas transplant was unnecessary for good endocrine function. (+info)
The regenerative deficit of peripheral nerves in experimental diabetes: its extent, timing and possible mechanisms.
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Diabetes mellitus is reported to impair peripheral nerve regeneration, but the extent, timing and selectivity of the deficit is unclear. We studied regeneration of motor and sensory fibres in mice with experimental diabetes induced using streptozotocin (STZ). The mouse model featured several advantages over its counterpart in rats given STZ, while exhibiting the expected slowing of motor conduction velocity. Serial studies addressed fibre regrowth for up to 10 weeks after both sciatic nerve crush injury and complete sciatic nerve transection. Following nerve crush, there was a delay in motor fibre reinnervation of tibial innervated interosseous muscles of diabetics, manifest as a slow recovery of the M-wave recorded from these muscles. Despite an apparent recovery in M-waves by 6 weeks, this was not accounted for by restitution of tibial axon numbers in diabetic mice. Histological studies distal to crush or transection identified substantial delays in the regrowth of the numbers and calibre of regenerating myelinated fibres in diabetics for up to 8-10 weeks. Moreover, this delay was observed in both the tibial (largely motor) and sural (non-motor) distal sciatic branches. There was an associated delay in macrophage invasion and their later resorption in the diabetic nerves, indicating that a potential mechanism of impaired regeneration might be abnormal macrophage participation in nerve repair. Our findings indicate that during nerve regeneration, diabetic motor and sensory fibres have substantial and persistent deficits in regrowth associated with abnormalities in macrophage participation. (+info)
Case complexity and clinical outcome in diabetes mellitus. A prospective study using the INTERMED.
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The aim of this study was to assess a population of patients with diabetes mellitus by means of the INTERMED, a classification system for case complexity integrating biological, psychosocial and health care related aspects of disease. The main hypothesis was that the INTERMED would identify distinct clusters of patients with different degrees of case complexity and different clinical outcomes. Patients (n=61) referred to a tertiary reference care centre were evaluated with the INTERMED and followed 9 months for HbA1c values and 6 months for health care utilisation. Cluster analysis revealed two clusters: cluster 1 (62%) consisting of complex patients with high INTERMED scores and cluster 2 (38%) consisting of less complex patients with lower INTERMED. Cluster 1 patients showed significantly higher HbA1c values and a tendency for increased health care utilisation. Total INTERMED scores were significantly related to HbA1c and explained 21% of its variance. In conclusion, different clusters of patients with different degrees of case complexity were identified by the INTERMED, allowing the detection of highly complex patients at risk for poor diabetes control. The INTERMED therefore provides an objective basis for clinical and scientific progress in diabetes mellitus. Ongoing intervention studies will have to confirm these preliminary data and to evaluate if management strategies based on the INTERMED profiles will improve outcomes. (+info)
Remodeling of networks of interstitial cells of Cajal in a murine model of diabetic gastroparesis.
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Patients with long-standing diabetes commonly suffer from gastric neuromuscular dysfunction (gastropathy) causing symptoms ranging from postprandial bloating to recurrent vomiting. Autonomic neuropathy is generally believed to be responsible for diabetic gastropathy and the underlying impairments in gastric emptying (gastroparesis) and receptive relaxation, but the specific mechanisms have not been elucidated. Recently, it has been recognized that interstitial cells of Cajal generate electrical pacemaker activity and mediate motor neurotransmission in the stomach. Loss or defects in interstitial cells could contribute to the development of diabetic gastroparesis. Gastric motility was characterized in spontaneously diabetic NOD/LtJ mice by measuring gastric emptying and by monitoring spontaneous and induced electrical activity in circular smooth muscle cells. Interstitial cells of Cajal were studied by Kit immunofluorescence and transmission electron microscopy. Diabetic mice developed delayed gastric emptying, impaired electrical pacemaking, and reduced motor neurotransmission. Interstitial cells of Cajal were greatly reduced in the distal stomach, and the normally close associations between these cells and enteric nerve terminals were infrequent. Our observations suggest that damage to interstitial cells of Cajal may play a key role in the pathogenesis of diabetic gastropathy. (+info)
Clinical characteristics of type 1 diabetic patients with and without severe hypoglycemia.
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OBJECTIVE: To investigate the frequency of severe hypoglycemia (SH) and hypoglycemic coma and to identify clinical and behavioral risk indicators in a nonselected population of type 1 diabetic patients. RESEARCH DESIGN AND METHODS: This study involved a retrospective clinical survey of 195 consecutive patients using a questionnaire addressing the frequency of SH (i.e., help from others required) and hypoglycemic coma during the previous year, general characteristics, behavior, hypoglycemia awareness, and the Hypoglycemia Fear Survey Data regarding diabetes, treatment, long-term complications, comorbidity, and comedication were obtained from the patients' medical records. RESULTS: A total of 82% of subjects were receiving intensive insulin treatment, and mean +/- SD HbA(1c) was 7.8 +/- 1.2%. Mean duration of diabetes was 20 +/- 12 years. The occurrence of SH (including hypoglycemic coma) was 150 episodes/100 patient-years and affected 40.5% of the population. Hypoglycemic coma occurred in 19% of subjects (40 episodes/100 patient-years). SH without coma was independently related to nephropathy (odds ratio [OR] 4.8 [95% CI 1.5-15.1]), a threshold for hypoglycemic symptoms of <3 mmol/l (4.8 [1.8-12.0]), and a daily insulin dose 0.1 U/kg higher (1.3 [1.0-1.6]) (all ORs were adjusted for diabetes duration and use of comedication). Hypoglycemic coma was independently related to neuropathy (3.9 [1.5-10.4]), (nonselective) beta-blocking agents (14.9 [2.1-107.4]), and alcohol use (3.5 [1.3-9.1]) (all ORs were adjusted for diabetes duration). CONCLUSIONS: SH and hypoglycemic coma are common in a nonselected population with type 1 diabetes. The presence of long-term complications, a threshold for symptoms of <3 mmo/l, alcohol use, and (nonselective) beta-blockers were associated with SH during the previous year. If prospectively confirmed, these results may have consequences for clinical practice. (+info)
Epalrestat, an aldose reductase ihibitor, reduces the levels of Nepsilon-(carboxymethyl)lysine protein adducts and their precursors in erythrocytes from diabetic patients.
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OBJECTIVE: To clarify the role of the polyol pathway in the intracellular formation of advanced glycation end products in human tissues, we examined the effects of epalrestat, an aldose reductase inhibitor, on the level of Nepsilon-(carboxymethyl)lysine (CML) along with 3-deoxyglucosone (3-DG) and triosephosphates in erythrocytes from diabetic patients. Plasma thiobarbituric acid-reactive substances (TBARS) were also determined as indicators of oxidative stress. RESEARCH DESIGN AND METHODS: Blood samples were collected from 12 nondiabetic volunteers, 38 untreated type 2 diabetic patients, and 16 type 2 diabetic patients who had been treated with 150 mg epalrestat/day. Blood samples were also collected from 14 of the untreated type 2 diabetic patients before and after the administration of epalrestat for 2 months. The amount of erythrocyte CML was determined by a competitive enzyme-linked immunosorbent assay, and 3-DG was measured by high-performance liquid chromatography RESULTS: In diabetic patients not treated with epalrestat, the erythrocyte CML level was significantly elevated above levels seen in nondiabetic individuals (49.9 +/- 5.0 vs. 31.0 +/- 5.2 U/g protein, P < 0.05) and was significantly lower in patients receiving epalrestat (33.1 +/- 3.8 U/g protein, P < 0.05). Similar results were observed with 3-DG. The treatment of patients with epalrestat for 2 months significantly lowered the level of erythrocyte CML (46.2 +/- 5.6 at baseline vs. 34.4 +/- 5.0 U/g protein, P < 0.01) along with erythrocyte 3-DG (P < 0.05), triosephosphates (P < 0.05), fructose (P < 0.05), sorbitol (P < 0.05), and plasma TBARS (P < 0.05) without changes in plasma glucose and HbA(1c) levels. A positive correlation was evident between the erythrocyte CML and sorbitol (r = 0.49, P < 0.01) or fructose (r = 0.40, P < 0.05) levels in diabetic patients. CONCLUSIONS: The results indicate that epalrestat administration lowers CML and associated variables and that polyol metabolites are correlated with CML in the erythrocytes of diabetic patients. The observed results suggest that aldose reductase activity may play a substantial role in the intracellular formation of CML in the mediation of reactive intermediate metabolites and oxidative stress. (+info)
Protection of sensory function and antihyperalgesic properties of a prosaposin-derived peptide in diabetic rats.
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BACKGROUND: Short-term diabetes causes sensory disorders in rats ranging from thermal hypoalgesia to exaggerated behavioral responses to other sensory stimuli. As impaired neurotrophic support may promote sensory nerve disorders during diabetes, the authors investigated whether TX14(A), a neurotrophic peptide derived from prosaposin, was able to ameliorate nerve disorders in diabetic rats. METHODS: TX14(A) was delivered by intraperitoneal or intrathecal injection to control or streptozotocin-diabetic rats in either single or multiple (three times weekly) dose regimens. Efficacy was measured against diabetes-induced disorders of sensory nerve conduction velocity, paw withdrawal latency to radiant heat, tactile response thresholds to von Frey filaments, and flinching after paw formalin injection. RESULTS: Prolonged TX14(A) treatment of diabetic rats prevented the progressive decline in large sensory fiber conduction velocity in the sciatic nerve, development of paw thermal hypoalgesia, and increased flinching after paw formalin injection. The effect on formalin hyperalgesia persisted for 48 h but not 72 h after injection. No effects were noted in control rats. A single injection of TX14(A) 30 min before testing did not alter thermal response latencies in control or diabetic rats but prevented formalin hyperalgesia in diabetic rats. Tactile allodynia and the prolonged paw thermal hyperalgesia to radiant heat after intrathecal delivery of substance P were also dose-dependently ameliorated in diabetic rats by a single injection of TX14(A), whereas no effects were observed on the responses to these tests in control rats. CONCLUSIONS: TX14(A) exhibits both neuroprotective and acute antihyperalgesic properties in diabetic rats without altering normal nociceptive function. (+info)