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Electrophysiological Evidence (electrophysiological + evidence)

Distribution by Scientific Domains

Medical Sciences	78%

Distribution within Medical Sciences

Neurology	64%
Pharmacology & Pharmaceutical Medicine	26%

Selected Abstracts

ELECTROPHYSIOLOGICAL EVIDENCE FOR THE INTERACTION OF SUBSTANCE P AND GLUTAMATE ON A, AND C AFFERENT FIBRE ACTIVITY IN RAT HAIRY SKIN

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2006
Qi Zhang
SUMMARY 1The purpose of the present study was to investigate whether there was a cooperative interaction between substance P (SP) and glutamate (GLU) administered subcutaneously on A, and C primary afferent fibre activity in dorsal hairy skin of the rat in vivo. The single unit activities of A, and C afferent fibres were recorded by isolation of fibre filaments from the dorsal cutaneous nerve branches and the effects of subcutaneous injections of low doses of SP, GLU and SP + GLU on activity were determined. 2Sub-threshold doses of SP (1 µmol/L, 10 µL) administered subcutaneously into the dorsal hairy skin had no effect on the afferent discharges of either A, or C units. 3The afferent discharges of 35% (11/31) of A, fibres and 33% (6/18) of C fibres were increased by local injection of the submaximal doses of GLU (10 µmol/L, 10 µL) into the receptive fields. 4The GLU-induced excitatory response was significantly enhanced by coinjection of subthreshold doses of SP. The mean discharge rates of A, fibres and C fibres were increased from 5.84 ± 1.54 and 5.02 ± 2.65 impulses/min to 19.91 ± 4.35 and 17.58 ± 5.59 impulses/min, respectively, whereas the excitatory proportions of A, and C fibres were increased from 35 and 33% to 84 and 83%, respectively. The duration of the excitation for A, fibres and C fibres was also significantly increased after coinjection of SP + GLU compared with that observed when either substance was given alone. 5The present study provides electrophysiological evidence for an interaction between receptors for SP and GLU on the fine fibres activities in rat hairy skin, which may be involved in the mechanisms of hyperalgesia. [source]

,-[11C]methyl-L-tryptophan uptake in patients with periventricular nodular heterotopia and epilepsy

EPILEPSIA, Issue 5 2008
Jun Natsume
Summary Background:,-[11C]methyl-L-tryptophan (,-MTrp) positron emission tomography (PET) is a promising tool in the localization of the epileptogenic area in selected group of focal epilepsy patients. Electrophysiological evidence suggests the involvement of the neocortex in periventricular nodular heterotopia (PVNH). Purpose: To determine whether ,-MTrp PET can detect neocortical changes in patients with PVNH. Methods: Four patients (2 male, mean age 28, range 23,35 years) with PVNH and intractable seizures were studied. The functional image in each patient was compared with those from 21 healthy controls (mean age 34.6 ± 14.2 years) by using statistical parametric mapping (SPM). The location of increased ,-MTrp uptake was compared with the location of the EEG focus. A significant cluster was defined as a cluster with a height p = 0.005 and an extent threshold 100. Results:,-MTrp PET revealed increased cortical uptake in two of four patients. The area of increased ,-MTrp uptake in one patient was widespread. In the other patient, the area of increased uptake did not include the region where most seizures were generated on EEG. ,-MTrp PET did not show increased uptake in the heterotopic nodules in any of the patients. Conclusions:,-MTrp PET suggests abnormal metabolism of tryptophan in the neocortex. The increased uptake may be diffuse and may not co-localize with the EEG focus. This preliminary study suggests that ,-MTrp PET may be useful, in conjunction with other evaluations, in localizing epileptic focus in patients with PVNH and refractory seizures. [source]

Polyneuritis cranialis with contrast enhancement of cranial nerves on magnetic resonance imaging

JOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 1 2003
A Morosini
Abstract: The disorder of multiple cranial nerve palsies without spinal cord involvement is referred to as polyneuritis cranialis (PC) and is rare. It is thought to be an acute post-infective polyneuropathy or a variant of Guillain,Barré syndrome. Electrophysiological evidence of demyelination has been reported, but no radiological abnormalities of the affected cranial nerves have been noted. We report a case of PC where contrast enhanced magnetic resonance imaging (MRI) showed enhancement of the peripheral segments of the oculomotor and abducens nerves. This case illustrates the utility of MRI in the assessment of cranial nerve palsies. [source]

Backward masking and visual mismatch negativity: Electrophysiological evidence for memory-based detection of deviant stimuli

PSYCHOPHYSIOLOGY, Issue 4 2007
István Czigler
Abstract Sequences composed of two different colored checkerboard patterns (standard and deviant) were presented to adults. Each pattern was followed by a mask with stimulus onset asynchronies (SOAs) varying between 14 and 174 ms. ERPs were recorded to the deviant and standard stimuli while the participants detected changes of a cross, which was continuously present at the center of the screen. In further experiments, the participants performed a Go-NoGo task detecting the deviant checkerboards. Deviant stimuli elicited an occipital negative component with 124,132 ms mean latency (the visual mismatch negativity, vMMN) at test (standard or deviant)-to-mask SOAs longer than 27 ms. No vMMN amplitude increase was observed beyond 40 ms test-to-mask intervals, whereas detection of deviant checkerboard patterns improved up to 174-ms SOA. Therefore the processes underlying vMMN elicitation cannot fully explain the overt detection of visual deviance. [source]

Electrophysiological evidence for altered early cerebral somatosensory signal processing in schizophrenia

PSYCHOPHYSIOLOGY, Issue 3 2004
Till D. Waberski
Abstract Various studies have indicated an impairment of sensory signal processing in schizophrenic patients. Anatomical and functional imaging studies have indicated morphological and metabolic abnormalities in the thalamus in schizophrenia. Other results give evidence for an additional role of cortical dysfunction in sensory processing in schizophrenia. Advanced analysis of human median nerve somatosensory evoked potentials (SEPs) reveals a brief oscillatory burst of low-amplitude and high-frequency activity (,600 Hz), the so-called high frequency oscillations (HFOs). The present study explores the behavior of HFOs in a cohort of schizophrenic patients in comparison to a group of controls. HFOs in the group of patients appeared with a delayed latency. In the low-frequency part of the SEPs an increase in amplitude was found. These results are interpreted to reflect a lack of somatosensory inhibition in the somatosensory pathway, either at a thalamic or a cortical level. [source]

Electrophysiological classification of P2X7 receptors in rat cultured neocortical astroglia

BRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010
W Nörenberg
Background and purpose:, P2X7 receptors are ATP-gated cation channels mediating important functions in microglial cells, such as the release of cytokines and phagocytosis. Electrophysiological evidence that these receptors also occur in CNS astroglia is rare and rather incomplete. Experimental approach:, We used whole-cell patch-clamp recordings to search for P2X7 receptors in astroglial,neuronal co-cultures prepared from the cerebral cortex of rats. Key results:, All the astroglial cells investigated responded to ATP with membrane currents, reversing around 0 mV. These currents could be also detected in isolated outside-out patch vesicles. The results of the experiments with the P2X [,,,-methylene ATP and 2,-3,-O-(4-benzoyl) ATP] and P2Y receptor agonists [adenosine 5,-O-(2-thiodiphosphate), uridine 5,-diphosphate, uridine 5,-triphosphate (UTP) and UDP-glucose] suggested the involvement of P2X receptors in this response. The potentiation of ATP responses in a low divalent cation or alkaline bath, but not by ivermectin, made it likely that a P2X7 receptor is operational. Blockade of the ATP effect by the P2X7 antagonists Brilliant Blue G, calmidazolium and oxidized ATP corroborated this assumption. Conclusions and implications:, Rat cultured cortical astroglia possesses functional P2X7 receptors. It is suggested that astrocytic P2X7 receptors respond to high local ATP concentrations during neuronal injury. [source]

Lower motor neuron involvement in perisylvian polymicrogyria

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 10 2006
Maria Clark MB BChir MRCP
Congenital bilateral perisylvian polymicrogyria syndrome (CBPS) has a cerebral cortical localization and its phenotype was thought to be purely central. This study of seven children with CBPS (five males, two females; mean age 5y [SD 3y 6mo]; range 1mo-11y 10mo) documents electrophysiological evidence of lower motor neuron involvement in association with congenital contractures (limb or jaw) in six of the seven children studied. This is not an expected association and does not conform to the traditional lesional classification system of the cerebral palsies. Possible pathogenic mechanisms are discussed but this association of upper and lower motor neuron involvement is likely to be a previously unsuspected part of a genetic or other pathogenic sequence. [source]

Visual Function in Infants with West Syndrome: Correlation with EEG Patterns

EPILEPSIA, Issue 7 2004
Teresa Randò
Summary:,Purpose: Several studies have reported behavioral and electrophysiological evidence of visual impairment during the active stage of West syndrome. The underlying mechanisms are, however, poorly understood, and little has been reported about the correlation between visual impairment, EEG patterns, and brain lesions. The aim of the study was to assess visual function at the onset of spasm and 2 months thereafter and relate visual findings to brain lesions and EEG features. Methods: Twenty-five infants with West syndrome were enrolled and studied with (a) a full clinical assessment including a battery of tests specifically designed to assess visual function, (b) a video-polygraphic study, and (c) brain magnetic resonance imaging (MRI). Besides brain neuroimaging and EEG comparison with visual function, an intra-EEG analysis was performed to investigate the possible relation of EEG patterns to fluctuating visual behavior (fixation and following). Results: Twenty-two children had at least one abnormal result on one or more of the tests assessing visual function at T0. Visual impairment at the spasm onset was related to the sleep disorganization rather than to the hypsarrhythmic pattern in awake EEG. After 2 months, both EEG features become significantly linked to visual function. Visual function improved in several cases after 2 months, in parallel with the seizure regression. No relation was found between EEG patterns and fluctuating visual behavior. Conclusions: The study supplies new evidence of the involvement of visual function in West syndrome. The presence of abnormal visual findings in infants without lesions on brain MRI suggests that visual abnormalities are due not only to brain injury but also to epileptic disorder per se. New insight is also provided into the possible mechanisms underlying clinical and EEG abnormalities. [source]

Surface protein patterns govern morphology, proliferation, and expression of cellular markers but have no effect on physiological properties of cortical precursor cells

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 11 2008
Anna K. Magnusson
Abstract The ability to differentiate and give rise to neurons, astrocytes, and oligodendrocytes is an inherent feature of neural stem cells, which raises hopes for cell-based therapies of neurodegenerative diseases. However, there are many hurdles to cross before such regimens can be applied clinically. A considerable challenge is to elucidate the factors that contribute to neural differentiation. In this study, we evaluated the possibility of steering neuronal maturation by growing cortical precursor cells on microscale surface patterns of extracellular matrix (ECM) proteins. When the cells were encouraged to extend processes along lines of ECM proteins, they displayed a much more mature morphology, less proliferation capacity, and greater expression of a neuronal marker in comparison with cells grown in clusters on ECM dots. This implied that the growth pattern alone could play a crucial role for neural differentiation. However, in spite of the strikingly different morphology, when performing whole-cell patch-clamp experiments, we never observed any differences in the functional properties between cells grown on the two patterns. These results clearly demonstrate that morphological appearances are not representative measures of the functional phenotype or grade of neuronal maturation, stressing the importance of complementary electrophysiological evidence. To develop successful transplantation therapies, increased cell survival is critical. Because process-bearing neurons are sensitive and break easily, it would be of clinical interest to explore further the differentiating capacity of the cells cultured on the ECM dot pattern, described in this article, which are devoid of processes but display the same functional properties as neurons with mature morphology. © 2008 Wiley-Liss, Inc. [source]

Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 62

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003
C Briani
Thalidomide seems to be effective in the treatment of cutaneous forms of lupus erythematosus refractory to other therapies. Peripheral neuropathy is the most severe side effect, but the incidence of neuropathy and its relation to thalidomide doses are still unclear. We prospectively monitored 12 patients treated with thalidomide for cutaneous lupus erythematosus in order to estimate the occurrence of side effects, particularly peripheral neuropathy. A total of 12 female patients, median age 38,6 years (range 26,56), with subacute or chronic cutaneous lupus erythematosus were considered. The patients were treated with low dose thalidomide (starting dose 100 mg, tapered to 50 mg/day or 50 mg alternative day) for up to 18 months. The average follow-up period was 8,6 months (range 2,18). Prior to, and regularly during treatment patients underwent neurological evaluation and electrophysiological study of at least 8 nerves in the 4 arms (ulnar, median, sural, peroneal nerves). At recruitment, one patient presented a sensory-motor peripheral neuropathy. Of the remaining 11 patients, six did not present electrophysiological evidence of neuropathy, one had a carpal tunnel syndrome and four showed slowing of ulnar nerve velocity at elbow. No patients developed neuropathy neither worsening of electrophysiological parameters during thalidomide treatment. The most common side effect was tremor, always reversible after withdrawing or reducing thalidomide. Paresthesias, somnolence, amenhorrea, constipation were also present. Only one patient had to stop the therapy for the occurrence, 10 days after taking 50 mg of thalidomide, of a severe, stabbing, "zoster-like" thoracic pain, which disappeared upon withdrawal of the drug. Started again on thalidomide, the symptoms reappeared and the patient definitely interrupted the therapy with benefit. All the 11 patients who continued on the therapy presented a significant improvement or remission of the cutaneous alterations. These preliminary data seem to indicate that low dose thalidomide is efficacious and tolerable for cutaneous lupus erythematosus. Peripheral neuropathy seems not to be a major side effect. A longer follow-up and the study of more patients are needed to confirm the results. [source]

Intraepidermal nerve fiber density as a marker of early diabetic neuropathy

MUSCLE AND NERVE, Issue 5 2007
T. Umapathi MB
Abstract The purpose of the study was to reliably identify an early stage of diabetic polyneuropathy (DPN) by measuring injury to epidermal nerve fibers. We compared intraepidermal nerve fiber density (IENFD) at the ankle and thigh of 29 diabetic subjects who had no clinical or electrophysiological evidence of small- or large-fiber neuropathy to that of 84 healthy controls. The mean ankle IENFD of diabetic subjects was 9.1 ± 5.0 mm and that of controls, 13.0 ± 4.8 mm (P < 0.001). The thigh IENFD did not differ significantly. The IENFD ratio (thigh IENFD divided by ankle IENFD) was 2.39 ± 1.30 in diabetic subjects and 1.77 ± 0.58 in controls (P < 0.001), indicating a length-dependent reduction of IENFD in diabetics. Ankle IENFD remained significantly lower and the IENFD ratio higher in diabetic subjects after adjusting for age. Two subjects had parasympathetic dysfunction, two had retinopathy, and two early nephropathy. Age, height, weight, duration of diabetes, and average HbA1c did not influence IENFD among diabetic subjects. We used receiver operating characteristic (ROC) curves to describe and compare the utility of various threshold values of ankle IENFD and IENFD ratio for the diagnosis of early DPN. The sensitivity and specificity of diagnosing DPN using ankle IENFD of less than 10 mm were 72.4% and 76.2%, respectively. Thus, asymptomatic diabetics have a measurable, length-dependent reduction of distal epidermal nerves. Analogous to microalbuminuria in diabetic nephropathy, reliable identification and quantitation of nascent diabetic neuropathy may have potential therapeutic implications. Muscle Nerve, 2007 [source]

A KCNQ channel opener for experimental neonatal seizures and status epilepticus,

ANNALS OF NEUROLOGY, Issue 3 2009
YogendraSinh H. Raol PhD
Objective Neonatal seizures occur frequently, are often refractory to anticonvulsants, and are associated with considerable morbidity and mortality. Genetic and electrophysiological evidence indicates that KCNQ voltage-gated potassium channels are critical regulators of neonatal brain excitability. This study tests the hypothesis that selective openers of KCNQ channels may be effective for treatment of neonatal seizures. Methods We induced seizures in postnatal day 10 rats with either kainic acid or flurothyl. We measured seizure activity using quantified behavioral rating and electrocorticography. We compared the efficacy of flupirtine, a selective KCNQ channel opener, with phenobarbital and diazepam, two drugs in current use for neonatal seizures. Results Unlike phenobarbital or diazepam, flupirtine prevented animals from experiencing development of status epilepticus when administered before kainate. In the flurothyl model, phenobarbital and diazepam increased latency to seizure onset, but flupirtine completely prevented seizures throughout the experiment. Flupirtine was also effective in arresting electrographic and behavioral seizures when administered after animals had developed continuous kainate-induced status epilepticus. Flupirtine caused dose-related sedation and suppressed electroencephalographic activity but did not result in respiratory suppression or result in any mortality. Interpretation Flupirtine appears more effective than either of two commonly used antiepileptic drugs, phenobarbital and diazepam, in preventing and suppressing seizures in both the kainic acid and flurothyl models of symptomatic neonatal seizures. KCNQ channel openers merit further study as potential treatments for seizures in infants and children. Ann Neurol 2009;65:326,336 [source]

Clinical and electromyographic deep tendon reflexes in polyneuropathy: diagnostic value and prevalence,

ACTA NEUROLOGICA SCANDINAVICA, Issue 4 2009
K. R. Sharma
Background,,, Evidence is accumulating that patients with polyneuropathy may present with normal clinical deep tendon reflexes (C-DTR). There are few studies that assessed the diagnostic utility of electromyographically recorded DTR (Er-DTR) in patients with polyneuropathy. Objectives,,, The objectives of this study were twofold: (i) to evaluate the prevalence of preserved C-DTR in polyneuropathy; (ii) diagnostic value of Er-DTR latency measurement in patients with polyneuropathy. Methods,,, We prospectively studied 38 controls and 185 patients with polyneuropathy. All subjects had evaluation of C-DTR, Er-DTR obtained from right biceps brachii (BR), right patellar (PR) and bilateral ankle reflexes (AR). Results,,, Of these 185 patients, 118 (63.8%) had chronic axonal neuropathy (CAN), 49 (26.5%) demyelinating polyradiculoneuropathy (DPN) and 18 (9.7%) small fiber neuropathy (SFN). The C-DTR were normal in 65 patients whereas 39 of these 65 (60%) patients had abnormalities of Er-DTR at one or more sites. Er-DTR latencies in patients with polyneuropathies were prolonged at all sites compared with controls (P < 0.01). Among patients with various types of polyneuropathies the Er-DTR, mean latencies at all the sites and latency indicative of demyelination (>150% of the normal mean) were higher in patients with DPN than that of CAN or SFN (P < 0.01). Conclusions,,, We conclude that C-DTR are preserved in 35.1% of the patients with polyneuropathies and Er-DTR should be performed in such patients in order to provide electrophysiological evidence of a polyneuropathy. Er-DTR are useful in distinguishing axonal from demyelinating disorders of peripheral nerve, and detection of subclinical involvement of large fibers in SFN. [source]