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Peripheral Nerve Function (peripheral + nerve_function)
Selected AbstractsC-peptide: new findings and therapeutic implications in diabetesCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2004John Wahren Summary In contrast to earlier views, new data indicate that proinsulin C-peptide exerts important physiological effects and shows the characteristics of an endogenous peptide hormone. C-peptide in nanomolar concentrations binds specifically to cell membranes, probably to a G-protein coupled receptor. Ca2+ - and MAP-kinase dependent signalling pathways are activated, resulting in stimulation of Na+, K+ -ATPase and endothelial nitric oxide (NO) synthase, two enzyme systems known to be deficient in diabetes. C-peptide may also interact synergistically with insulin signal transduction. Studies in intact animals and in patients with type 1 diabetes have demonstrated multifaceted effects. Thus, C-peptide administration in streptozotocin-diabetic animals results in normalization of diabetes-induced glomerular hyperfiltration, reduction of urinary albumin excretion and diminished glomerular expansion. The former two effects have also been observed in type 1 diabetes patients given C-peptide in replacement dose for up to 3 months. Peripheral nerve function and structure are likewise influenced by C-peptide administration; sensory and motor nerve conduction velocities increase and nerve structural changes are diminished or reversed in diabetic rats. In patients with type 1 diabetes, beneficial effects have been demonstrated on sensory nerve conduction velocity, vibration perception and autonomic nerve function. C-peptide also augments blood flow in several tissues in type 1 diabetes via its stimulation of endothelial NO release, emphasizing a role for C-peptide in maintaining vascular homeostasis. Continued research is needed to establish whether, among the hormones from the islets of Langerhans, C-peptide is the ugly duckling that , nearly 40 years after its discovery , may prove to be an endogenous peptide hormone of importance in the treatment of diabetic long-term complications. [source] Sorbitol and myo -inositol levels and morphology of sural nerve in relation to peripheral nerve function and clinical neuropathy in men with diabetic, impaired, and normal glucose toleranceDIABETIC MEDICINE, Issue 4 2000G. Sundkvist Abstracts Aims Sorbitol and myo -inositol levels and morphology of sural nerve were compared with nerve function and clinical neuropathy in men with diabetic, impaired (IGT), and normal glucose tolerance. Methods After neurography of sural nerve and determinations of sensory thresholds for vibration, warm and cold on the foot, whole nerve sural nerve biopsy was performed in 10 men with Type 1 diabetes mellitus, 10 with IGT, and 10 with normal glucose tolerance. Polyol levels were assessed by gas,liquid chromatography/mass spectrometry. Results Sural nerve amplitudes were significantly lower and sorbitol levels significantly higher in diabetic patients (median (interquartile range)) (3.7 (3.5) ,V and 643 (412) pmol/mg protein, respectively) both compared with IGT (11.3 (10.6) ,V; P = 0.04 and 286 (83) pmol/mg protein; P = 0.0032, respectively) and normally glucose tolerant (10.0 (11.6); P = 0.0142 and 296 (250) pmol/mg protein; P = 0.0191, respectively) subjects. There were no differences in nerve morphology between the three groups. Nerve myo -inositol levels correlated, however, positively with cluster density (rs = 0.56; P = 0.0054). In diabetic and IGT subjects, sural nerve amplitudes (2.6 (3.8) vs. 12.1 (10.6) ,V; P = 0.0246) and myelinated nerve fibre density (MNFD; 4076 (1091) vs. 5219 (668) nerve fibres/mm2; P = 0.0021) were significantly lower in nine subjects with clinical neuropathy than in 10 without. Conclusions Nerve degeneration (i.e. MNFD) correlated with clinical neuropathy but not with glucose tolerance status whereas nerve myo -inositol levels positively correlated with signs of nerve regeneration (i.e. increased cluster density). [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 79JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003U Del Carro Peripheral neuropathy is one of the most common secondary complications of diabetes mellitus, causing severe and prolonged morbidity. However, clinical and experimental studies have reported that careful glucose control may prevent, stabilize, and/or reverse neuropathy and other chronic diabetic complications. Unfortunately, insulin therapy does not prevent the development or progression of chronic lesions in the vessels, kidneys, eyes, or nerves of the diabetic patient. There is great interest in investigating other forms of endocrine replacement therapy, such as transplantation of the pancreas or of the islets of Langerhans (IT). Diabetic polyneuropathy (DP) evolution is characterized by progressive demyelination and axonal loss and is manifested by signs and symptoms on physical examination and abnormalities in nerve conduction studies (NCS). NCS provide reliable, noninvasive, objective measures of peripheral nerve function and constitute the most important technique for the evaluation of the severity of DP in clinical trials. Several research groups have demonstrated that skin biopsy with measurement of intraepidermal nerve fiber density is another method minimally invasive and repeatable that provides direct pathologic evidence of axonal damage in diabetic neuropathy. Fifty-one consecutive IDDM patients with or without end stage renal disease were enrolled at the moment of islet (Is), kidney (KD), kidney-pancreas (KP) or kidney-islet (KI) transplantation. Patients underwent skin biopsy punch, neurologic examination and neurophysiological investigation. Particularly, 20 pts underwent KP tx, 16 KD tx, 10 islet tx and 5 KI. The patients were comparable for duration of diabetes, dialysis (when present), age, lipid profile. In half of the patients a follow-up of 2 years has been reached. After KP tx, and partially with KI, a complete normalization of glycometabolic control has been achieved, with statistically lower HbA1c in comparison with KD group (KP = 6.2; 0.1% vs. KD = 8.4; 0.5%; p < 0.01). In the KI/Is group, a long-term restoration of islet endocrine function has been achieved, with insulin independence. When this has been lost, a persistent secretion of C-peptide was shown for a long period of time. This was correlated with a global improvement quality of life and vascular structure. Preliminary results will be presented. [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 43JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003S Amadio Study aim: the Ebf gene family has been implicated in several developmental processes, ranging from B-cell development to neuronal differentiation. As the murine Ebf2 gene is expressed in numerous sites of nervous system, Ebf2-null mice develop hypogonadotropic hypogonadism, due to defective migration of gonadotropin releasing hormone-synthesizing neurons, and a peripheral neuropathy as well. Therefore, we aimed to study whether electrophysiological tests would be able to detect abnormalities of peripheral nerve function. Methods: 2 groups of mice were studied, which consisted of 8 Ebf2-/- mice and 9 age-matched controls. The sciatic nerve was stimulated at the ankle and at the ischiatic notch; the compound motor action potential (cMAP) was recorded from the paw muscles with a pair of needle electrodes to measure the motor conduction velocity (MCV). Results: MCV mean values were lower in Ebf2-/-(21.8 m/sec; SD 2.9) than in controls (35.2 m/sec; SD 2.6) and the difference was significant (p < 0.001). The mean cMAP amplitude was also decreased in Ebf2-/-(6.2 mV; SD 2.7) as compared to controls (9.3 mV; SD 2.6, p < 0.05). Conclusions: electrophysiological tests demonstrated a sharp decrease of sciatic MCV in Ebf2-/- mouse, as consequence of defective axon sorting, segmental dysmyelination and axonal damage revealed by pathological study. [source] Age-Induced Neuropathy In RatsJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000S Yagihashi We studied the effects of exogenously administered advanced glycation end-products (AGE) on the peripheral nerve function and structure in normal rats. Normal Wistar rats aged 6 weeks were injected intraperitoneally with purified AGE (20 mg/kg/day) produced by incubation of glucose with bovine serum albumin (BSA) for 12 weeks. Control rats were treated with BSA alone. One of AGE-treated groups was co-treated with 50 mg/kg aminoguanidine (AG). During the experimental period, body weight and blood glucose levels were not affected in AGE-treated rats. Serum AGE levels were elevated two fold in AGE-treated group whereas BSA treated rats maintained normal levels, whereas tissue AGE levels in sciatic nerve were not increased in treated group. AG did not alter the levels of serum AGE. AGE-treated rats exhibited significant delay of motor nerve conduction velocity by 30% and reduction of sciatic nerve in Na,K-ATPase activity by 25% in AGE-treated rats. AG treatment significantly inhibited these changes. Immunostains on the cross-sections of sciatic nerve demonstrated significant increase in cells positive for 8 hydroxy-deoxyguanosine, a marker of oxidative stress-induced DNA injury, in AGE-treated group. AG treatment significantly inhibited this reaction. There was no difference in morphometric data on myelinated fibers in sural nerve among the experimental groups. AGE-injected rats thus showed the neuropathic changes, similar to those found in experimentally-induced diabetic animals and it is therefore suggested that AGE have a pathogenetic role in the development of diabetic neuropathy through induction of excessive oxidative stress. Supported by Juvenile Diabetes Foundation International (1-2000-263), Japan Diabetes Foundation, Japanese Ministry of Science, Education, Sports and Culture. [source] Recovery of touch after median nerve lesion and subsequent repairMICROSURGERY, Issue 1 2003M.F. Meek M.D., Ph.D. Many techniques have been developed for the evaluation of peripheral nerve function. Consequently, physicians use different techniques in the clinic. This study describes the evaluation of touch after median nerve lesions in the forearm and repair. In order to evaluate touch, 25 patients, aged 11,51 years (mean, 29 years), were evaluated 3,10.5 years (mean, 5 years) after median nerve repair. The evaluation included the moving two-point discrimination test and Semmes-Weinstein monofilaments. We showed that 32% good,excellent results can be obtained with difficult nerve lesions. The results could have been improved if a sensory reeducation regime had been applied. © 2003 Wiley-Liss, Inc. MICROSURGERY 23:2,5 2003 [source] Neuromuscular involvement in various types of Ehlers,Danlos syndrome,ANNALS OF NEUROLOGY, Issue 6 2009Nicol C. Voermans MD Objective Ehlers,Danlos syndrome (EDS) is a clinically and genetically heterogeneous group of heritable connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. Muscle involvement is plausible based on recently discovered interactions between muscle cells and extracellular matrix molecules; however, muscle symptoms are only sporadically reported. We designed a cross-sectional study to find out whether neuromuscular features are part of EDS. Methods Standardized questionnaires, physical examination, nerve conduction studies, electromyography, muscle ultrasound, and muscle biopsy were performed in 40 EDS patients with the vascular, classic, tenascin-X (TNX),deficient type EDS, and hypermobility type of EDS caused by TNXB haploinsufficiency. Results Muscle weakness, myalgia, and easy fatigability were reported by the majority of patients. Mild-to-moderate muscle weakness (85%) and reduction of vibration sense (60%) were common. Nerve conduction studies demonstrated axonal polyneuropathy in five patients (13%). Needle electromyography myopathic features in nine patients (26%) and a mixed neurogenic-myopathic pattern in most (60%). Muscle ultrasound showed increased echo-intensity (48%) and atrophy (50%). Mild myopathic features were seen on muscle biopsy of five patients (28%). Overall, patients with the hypermobility type EDS caused by TNXB haploinsufficiency were least affected. Interpretation Mild-to-moderate neuromuscular involvement is common in various types of EDS, with a remarkable relation between residual TNX level and degree of neuromuscular involvement, compatible with a dose,effect relation. The findings of this study should increase awareness of neuromuscular symptoms in EDS patients and improve clinical care. They also point to a role of the extracellular matrix in muscle and peripheral nerve function. This is an updated version of this article that originally published online on June 29, 2009. Ann Neurol 2009;65:687,697 [source] Schwann cell expression of PLP1 but not DM20 is necessary to prevent neuropathyANNALS OF NEUROLOGY, Issue 3 2003Michael E. Shy MD Proteolipid protein (PLP1) and its alternatively spliced isoform, DM20, are the major myelin proteins in the CNS, but are also expressed in the PNS. The proteins have an identical sequence except for 35 amino acids in PLP1 (the PLP1-specific domain) not present in DM20. Mutations of PLP1/DM20 cause Pelizaeus-Merzbacher Disease (PMD), a leukodystrophy, and in some instances, a peripheral neuropathy. To identify which mutations cause neuropathy, we have evaluated a cohort of patients with PMD and PLP1 mutations for the presence of neuropathy. As shown previously, all patients with PLP1 null mutations had peripheral neuropathy. We also identified 4 new PLP1 point mutations that cause both PMD and peripheral neuropathy, three of which truncate PLP1 expression within the PLP1-specific domain, but do not alter DM20. The fourth, a splicing mutation, alters both PLP1 and DM20, and is probably a null mutation. Six PLP1 point mutations predicted to produce proteins with an intact PLP1-specific domain do not cause peripheral neuropathy. Sixty-one individuals with PLP1 duplications also had normal peripheral nerve function. These data demonstrate that expression of PLP1 but not DMSO is necessary to prevent neuropathy, and suggest that the 35 amino acid PLP1-specific domain plays an important role in normal peripheral nerve function. Ann Neurol 2003 [source] Effects of the antiepileptic drugs on peripheral nerve functionACTA NEUROLOGICA SCANDINAVICA, Issue 1 2010E. Boylu Objective,,, We aimed to compare the effects of antiepileptic drugs and provide findings of peripheral nerve impairment using standard electrophysiological techniques. Materials and methods,,, Young adult outpatients with epilepsy on monotherapy for no less than 6 months with carbamazepine (CBZ), valproic acid (VPA), oxcarbazepine (OXC) and topiramate (TPM) were examined. Patients who had any other disease that could effect nerve conduction studies and who had neuropathic symptoms were excluded. Results,,, Each group contained 15 patients and 20 healthy subjects were examined as the control group. Prolonged latency of median sensory nerve (P = 0.004), ulnar sensory nerve (P = 0.01) and sural nerve (P = 0.003) with a diminished nerve conduction velocity was observed in the CBZ group (P = 0.014, P = 0.002, P = 0.025, respectively). No correlation was found between VPA, OXC and TPM and the nerve conduction studies (P > 0.05). Conclusions,,, Valproic acid, oxcarbazepine and topiramate don't have effects on nerve conduction studies. Mild electrophysiological changes contribute to carbamazepine therapy. [source] | ||||||||||