Potential Duration Research Articles

Re-employment Rates of Older Unemployed Workers: Decomposing the Effect of Birth Cohorts and Policy Changes

In many European countries, re-employment probabilities of older unemployed workers are relatively low. While there is evidence that financial incentives and search obligations are effective to increase the job prospects of older workers, recent research also stresses the importance of birth cohort effects. These cohort effects may in turn stem from higher educational attainment levels and better health conditions of future generations of older workers. This paper empirically assesses the relative importance of both explanations, using a registered data set of unemployment insurance spells between 1999 and 2008 for the Netherlands. Using a Linear Probability Model, we decompose the effects of birth cohorts, age, calendar time and two policy measures that were targeted at older unemployed workers—i.e. increased job search obligations in 2004 and shorter potential benefit durations (PBD) in 2006. We find that policy effects predominantly explain the increased job return rates of unemployed of 55 years and older from 1999 to 2008. The introduction of search requirements has increased the one-year re-employment probability of eligible older men with about 5 % point, while the reduction in PBD has caused the one-year re-employment probability of eligible men to increase with 3 % point.

Toxicity Induced by Cumene Hydroperoxide in Leech Retzius Nerve Cells: the Protective Role of Glutathione

In the present study, we studied the ability of glutathione (GSH) to detoxify exogenously applied cumene hydroperoxide (CHP). Exposure of leech Retzius nerve cells to CHP (1.5 mM) induced a marked prolongation of the spontaneous spike potential of these cells. Early after depolarization, and a cardiac-like action potential with a rapid depolarization followed by a sustained depolarization or plateau, which is terminated by a rapid repolarization were recorded. GSH (0.2 mM) significantly inhibited the effects of CHP on the duration of the action potential and suppressed CHP-induced spontaneous repetitive activity. Voltage-clamp recordings showed that CHP (1.5 mM) caused significant changes in the outward potassium currents. The fast and slow steady part of the potassium outward current was reduced by 46% and 39%, respectively. GSH applied in a concentration of 0.2 mM partially blocked the effect of CHP on the calcium-activated potassium currents. The fast and slow calcium-activated potassium currents were suppressed by about 20% and 15%, respectively. These results suggest that the neurotoxic effect of CHP on spontaneous spike electrogenesis and calcium-activated potassium currents of leech Retzius nerve cells was reduced in the presence of GSH.

The patterns of myoelectrical activity and reaction for teat stimulation recorded in highly productive dairy cows’ udders

The aim of the study was to evaluate electrical properties of the mammary gland of dairy cow during manual and mechanical milking and to adapt the electrographic method for analysis of udder physiology. Udder myoelectrical activity was measured on 10 healthy highly productive dairy cows of Slovak Pied cattle breed. The electrical activity of four quarters of the udder was recorded simultaneously using four bipolar electrodes. The udder was stimulated by delicate two-finger massage, manual milking and mechanical milking. During the experiment the duration of the reaction for stimulation and the amplitude of spike dischargers were listed. The udder stimulation through palpational massage of the teat end, manual and mechanical milking caused immediate reaction. The udder responded to stimulation with an increase in myoelectrical activity: increase in discharge frequency to 2.33 ± 0.6 per min and an increase in discharge amplitude with the average of 457 ± 147 µV. The average count of spike discharges was 3.86 ± 0.97, the average duration of the action potential was 8.12 ± 1.68 s and the average myoelectrical index was 31 ± 4%. Manual milking caused the highest increase in the udder myoelectrical activity. Evaluation of the mammary gland myoelectrical activity may provide an alternative method to study milk ejection disorders and to diagnose mastitis.

Effect of Selective Stimulation of Muscarinic M3 Cholinoceptors on Electrical and Contractile Activity of Rat Ventricular Myocardium

We studied the effect of selective activation of muscarinic M3receptors on electrical activity in the isolated preparation of rat ventricular myocardium as well as contractile activity of the left ventricle of Langendorff-perfused isolated heart. Application of muscarinic agonist pilocarpine (10(-5)M) against the background of selective blockade of subtype 2 muscarinic receptors with methoctramine (10(-7)M) markedly shortened the duration of action potentials in the isolated ventricular myocardium and reduced the amplitude and maximum rates of left-ventricular pressure rise and decay in the isolated heart paced at a fixed rate. All these effects were significantly suppressed by selective M3receptor blocker 4-DAMP (10(-8)M), which attested to the involvement of M3muscarinic receptors.

Laryngeal electromyography in dysphonic patients with incomplete glottic closure

The lack of specificity in laryngoscopical examination requires that the diagnosis of superior laryngeal and recurrent laryngeal nerve involvement be carried out with the aid of electromyography. ObjectiveThis study aims to assess the electrophysiological function of the superior and inferior laryngeal nerves by measuring the electrical activity of the muscles they innervate in dysphonic patients with incomplete closure of the vocal folds during phonation. MethodThirty-nine patients with incomplete glottic closure were enrolled in a prospective study and had their cricothyroid, thyroarytenoid, and lateral cricoarytenoid muscles examined bilaterally through electromyography. Insertion activity, electrical activity at rest (fibrillation, positive wave and fasciculation) and during muscle voluntary contraction (recruitment, amplitude, potential length and latency between electrical activity and phonation) were measured. ResultsNo altered test results were observed for parameters insertion activity and electrical activity at rest. None of the patients had recruitment dysfunction. The mean electrical potential amplitude values were within normal range for the tested muscles, as were potential durations and latency times between the onset of electrical activity and phonation. ConclusionNo signs of denervation were seen in the thyroarytenoid, cricothyroid, and lateral cricoarytenoid muscles of the studied patients.

Nitric oxide modulates intensity of non-quantal acetylcholine release in myocardium of the right atrium of rat

The main parasympathetic neurotransmitter acetylcholine (ACh) is released in the myocardium from the intramural postganglionic parasympathetic nerve endings. The mechanism of non-quantal ACh release has been recently demonstrated in these neurons. Non-quantal ACh release does not depend on exocytosis of ACh-containing vesicles in response to nerve impulse activity but is assumed to be mediated by the high-affinity choline uptake system. The intensity of non-quantal ACh release in the myocardium correlates with the degree of manifestation of the effects of acetylcholinesterase inhibitors inducing the accumulation of non-quantal ACh in the myocardium. The present study deals with the influence of putative modulators of non-quantal ACh release: nitric oxide (NO) and ATP, on the intensity of cholinergic effects induced by organophosphorous acetylcholinesterase inhibitor paraoxon. Intracellular registration of bioelectrical activity in isolated right atrium preparations from rats was used. Under normal conditions, paraoxon (10−7–10−5 M) induced a marked decrease in the action potential (AP) duration at a level of 50 and 90% repolarization in the working right atrial myocardium and slowed down the sinus rhythm. ATP, which is known to suppress nonquantal ACh release in the neuromuscular junction, did not induce significant reduction or augmentation of the effects of paraoxon (5 × 10−6 M). The NO donors, sodium nitroprusside (10−5 M) and SNAP (10−4 M), significantly reduced the paraoxon-induced AP shortening. Moreover, sodium nitroprusside decreased the negative chronotropic effect of paraoxon by 43.7%. On the contrary, NO synthase inhibitor L-NAME (10−4 M), which is known to suppress endogenous NO production, augmented the AP shortening caused by paraoxon. It may be deduced that NO is a universal regulator of non-quantal ACh release intensity both in the myocardium and in the neuromuscular junction.

Electromechanical coupling in cardiomyocytes from transmural layers of guinea pig left ventricle

The electrical and mechanical activity of heart ventricle cardiomyocytes is known to vary depending on the spatial location of cells in the wall, in particular, transmurally from the sub-endocardial layer to the sub-epicardial one. To investigate intracellular mechanisms of the functional heterogeneity of cardiomyocytes we developed mathematical models of the electromechanical coupling in cardiomyocytes from different transmural layers across the left ventricle (LV) wall of guinea pig. It is shown that the mechanisms of both direct linkages and feedback in the electromechanical coupling contribute to differences in both the shape and duration of action potential, and speed characteristics of contraction between isolated cardiac myocytes from the sub-endocardial and sub-epicardial layers.

The Inflammatory Chemokine CXCL10 Modulates Synaptic Plasticity and Neuronal Activity in the Hippocampus

Chemokines, a family member of cytokines, have been shown to play a major role in central nervous system inflammation. Among other chemokines, CXCR3 and its ligand CXCL10 are involved in the pathophysiology of several neuroinflammatory conditions. Most of these conditions are also associated with an increased incidence of seizure or epilepsy. Using age-matched wild-type (WT), as well as CXCR3-receptor-deficient (CXCR3-KO) mice, the present study aimed to investigate the effect of the chemokine CXCL10 and its receptor CXCR3 on synaptic plasticity as well as neuronal activities in hippocampal brain slices. Using field potential and intracellular recordings, the effect of exogenous CXCL10 on tetanus-induced long-term potentiation (LTP) as well as the neuronal spike activity was evaluated in hippocampal CA1 area. Exogenous application of CXCL10 enhanced LTP in WT mice, whereas it exerted no significant effect on CXCR3-KO mice. During intracellular recordings of spontaneous spike activity, exogenous application of CXCL10 significantly enhanced the amplitude, duration, and after-hyperpolarization of action potentials in slices obtained from WT mice compared to CXCR3-KO mice. In addition, CXCR3-KO mice exhibited a lower GABAA-mediated excitation in hippocampal CA1 neurons compared to WT mice. These data show that the inflammatory chemokine CXCL10, probably via its receptor CXCR3, modulates neuronal activity and synaptic plasticity in the hippocampus. CXCL10 may be involved in seizures observed during neuroinflammatory diseases such as meningitis and encephalitis.

Site-specific criteria for the completion of landfill aftercare

Municipal solid waste (MSW) landfills need to be managed after closure to assure long-term environmental compatibility. Aftercare can be completed when the authorities consider the landfill not likely to pose a threat to humans and the environment. In this work, a methodology for deriving site-specific aftercare completion criteria is presented and its application is illustrated via a case study. The evaluation method combines models addressing waste emission behavior, long-term barrier performance, and pollutant migration to assess the potential impact of landfill emissions on the environment. Based on the definition of acceptable impact levels at certain points of compliance, scenario- and pollutant-specific aftercare completion criteria are derived. The methodology was applied to a closed MSW landfill in Austria and potential aftercare durations were determined. While landfill gas emissions may become environmentally tolerable within decades at the site, leachate-related aftercare measures were expected to be necessary for centuries (primarily as a result of ammonium). Although the evaluation comes with large uncertainties, it allows for linking aftercare intensity and duration with respect to an environmentally compatible state of the landfill in the absence of aftercare. However, further case studies including regulatory review and acceptance are needed to use the methodology in a decision support tool on aftercare completion.

Abstract 136: Novel Disease Analysis Using Long QT Syndrome-Specific Induced Pluripotent Stem Cells

[Background] Although previous reports have indicated that long QT syndrome-specific iPS cells (LQTS-iPSCs)-derived cardiomyocytes recapitulated disease phenotypes, those patients were previously diagnosed with mutated channel profiles. In reality, most patients have no such specific information. To address whether iPSCs could be used for personalized disease characterization, we generated iPSCs from a sporadic LQTS patient with unknown disease cause. [Methods and Results] 1 We generated iPSCs from control (n = 2) and a patient with LQTS, and differentiated into cardiomyocytes through embryoid body (EB) formation. 2 Electrophysiological analysis of the LQTS-iPSCs-derived EBs using multi electrode array system revealed that the duration of the field potential (FPD) was markedly prolonged compared with the control (388.9 ± 44.3 msec vs 202.3 ± 16.3 msec, P<0.01). 3 We tested several drugs affecting QT prolongation to clarify the electrophysiological properties. The IKr blocker E4031 significantly prolonged FPD (% change 1.21 ± 0.02, P<0.01) and induced frequent severe arrhythmia, not only early-after depolarization (n = 8/16 vs n = 1/16) but also torsades de pointes-like arrhythmia, only in LQTS (n = 4/16 vs n = 0/16). The IKs blocker, chromanol 293B did not prolong FPD in LQTS but it significantly prolonged FPD in the control (% change 1.09 ± 0.04, NS vs 1.44 ± 0.07, P<0.01), suggesting the involvement of IKs disturbance in the patient. Isoproterenol induced ventricular tachycardia-like arrhythmia only in LQTS, which was blocked by propranolol. These data strongly suggested a functional impairment in the patient’s IKs channel; genotype analysis for KCNQ1 gene revealed a novel heterozygous mutation, 1893delC. 4 Patch clamp analysis and immunostaining confirmed a dominant-negative role for 1893delC in IKs channel through a trafficking deficiency. [Conclusions] LQTS-iPSCs-derived cardiomyocytes recapitulated the disease phenotypes, and they can be utilized for identification of the disease cause and genotype. This study demonstrated that iPSCs could be useful to characterize the disease, drug responses, diagnosis and genotyping in patients with sporadic LQTS, which in turn may facilitate medical therapies in the clinical settings.

Abstract 215: Systemic Inflammation Exacerbates Electrophysiological Remodeling and Arrhythmia Following Myocardial Infarction

Introduction: Inflammatory macrophages infiltrate the heart following myocardial infarction (MI) and secrete proteases and cytokines that may contribute to adverse electrophysiological remodeling. Atherosclerosis, the leading cause of MI, is associated with elevated systemic inflammation. Using a novel combination of optical mapping and molecular imaging, we sought to determine if systemic inflammation exacerbates electrophysiological remodeling and arrhythmogenesis. Methods: A protease activatable fluorescent sensor (Prosense680) was injected I.V. 4 days post MI in mice. Optical mapping of transmembrane potential was performed 5 days post MI on Langendorff-perfused hearts to assess electrophysiology. Fluorescence reflectance imaging of Prosense680 was then performed to visualize and quantify inflammatory protease activity. Lipopolysaccharide (LPS:10 μ g/day, n=6) was injected I.P. to promote systemic inflammation or saline as control (SAL, n=7). Results: Inflammation levels were greater in MI+LPS vs MI+SAL hearts (5.626±1.5 vs 1.73±0.25 A.U., p<0.02) and negligible in sham-operated hearts (SH, n=4). MI+LPS hearts had prolonged action potential (AP) duration vs MI+SAL vs SH (62±4.5 vs 56±1.8 vs 45±3.7 ms, p<0.05) and increased AP rise time (5.5±0.5 vs 4.2±0.2 vs 2.9±0.3 ms, p<0.05). A single premature pacing stimulus induced ventricular tachycardia in 67%(4 of 6) of MI+LPS vs 15%(1 of 7) MI+SAL vs 0% (0 of 4) SH, p<0.02. Conclusions: Elevated post-MI inflammation may contribute to electrophysiological remodeling and arrhythmias. These findings have important implications for the etiology of post-MI arrhythmias in humans with systemic inflammation.

Heterogeneity of Intrinsic Repolarization Properties Within the Human Heart: New Insights From Simulated Three-Dimensional Current Surfaces

Heterogeneity of repolarization properties is pivotal for both physiology and pathology of the heart and mathematical models of different cardiac cell types that are tuned to experimental data in order to reproduce it in silico. Repolarization heterogeneity is described most of the times with reference to one or the other of the many repolarization parameters, like action potential (AP) form and duration, or the maximum conductance of a given ion current, which are nonlinearly connected and frequently overdetermined. A compact representation of models dynamics would help their standardization, their use, and the understanding of the underlying physiology. A 3-D representation of cardiac AP derived from the measure of instantaneous current-voltage relationships during repolarization has been previously described. Here, it is shown that such a representation compactly summarizes important features of repolarization which are relevant particularly for what concerns its electrotonic modulation within the human heart. It is found that, according to the tested models, late phase of AP repolarization displays autoregenerativity only within the ventricle, and that this property is heterogeneously distributed across the wall. Three-dimensional current representations of the AP also provide precise estimation of the time course of membrane resistance, which changes throughout the heart, and can be used to predict entrainment of repolarization during AP propagation.

Effects of duration of surgery flash-induced visual evoked potentials in patients undergoing spinal surgery in prone position

Objective To investigate the effects of duration of surgery on flash-induced visual evoked potentials (VEP) in patients undergoing spinal surgery in prone position.Methods Eighty-two ASA Ⅰ or Ⅱ patients of both sexes aged 20-76 yr weighing 43-96 kg undergoing spinal surgery in prone position were divided into 3 groups according to the duration of surgery:group S≤2 h ( n =34) ; group M 2-4 h ( n =38) and group L≥4 h ( n =10).VEP was monitored using protektor VEP monitoring device (Xltek Co.,Canada).The latency,amplitude and recovery time of wave P100 were recorded before and 10 min after induction of anesthesia and at the end of surgery.Results Compared with group S,the amplitude of wave P1000 was significantly decreased at the end of surgery in group M,the lantency of wave P100 was significantly prolonged,while the amplitude of wave P100 was decreased at the end of surgery in group L ( P ＜ 0.05).Compared with group M,the lantency of wave P100 was significantly prolonged,while the amplitude of wave P100 was decreased at the end of surgery in group L ( P ＜ 0.05).Compared with groups S and M,the recovery time of wave P100 was significantly prolonged in group L ( P ＜0.05).There was no significant difference in the recovery time of wave P100 between groups S and M ( P ＞ 0.05).Conclusion Duration of surgery (≥4 h) can affect flash-induced VEP,the longer the duration,the stronger the effects. Key words: Time; Surgical procedures,operative, Evoked potentials, visual; Spine

Cochrane Review: Steroids for symptom control in infectious mononucleosis

AbstractBackgroundInfectious mononucleosis (glandular fever) is associated with fatigue, fever, sore throat and swollen lymph nodes. The severity of symptoms can vary. In extreme cases, throat swelling can cause breathing difficulties and other complications requiring hospitalisation. The duration of symptoms is variable and can last for months. Few treatments are available and there are no universal criteria for using steroids in glandular fever. While steroids are generally reserved for severe complications, there are reports of practitioners treating symptomatic people with steroids. Infectious mononucleosis often affects young people at a time in their education where they need to be continually productive and the potential long duration of the condition is perhaps a key factor in prescribing such a potent drug for symptom control.ObjectivesTo determine the efficacy and safety of steroids for symptom control in infectious mononucleosis.Search methodsWe searched CENTRAL (2011, Issue 1), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to February Week 3, 2011) and EMBASE (1974 to February 2011).Selection criteriaRandomised controlled trials (RCTs) comparing the effectiveness of steroids with placebo or other interventions for symptom control for people with documented infectious mononucleosis.Data collection and analysisWe independently assessed trial inclusion. Where appropriate, it was intended to combine trial results in a meta‐analysis.Main resultsSeven trials were included. Heterogeneity between trials prevented combined analysis. Trials under‐reported methodological design features. Across the trials, no benefit was found in 8/10 assessments in health improvement. Two trials found at 12 hours benefit of steroid therapy over placebo in reducing sore throat (eight‐day course OR 21.00, 95% CI 1.94 to 227.20; one‐dose OR 4.20, 95% CI 1.08 to 16.32) but benefit was not maintained. In combination with an antiviral drug, another trial reported participants in the steroidal group had less pharyngeal discomfort between two to four days (OR 0.31, 95% CI 0.09 to 1.08). Across the trials effects on other common symptoms were less clear. Two trials set out to measure safety; they document no major adverse effects. In two other trials adverse events were reported, including respiratory distress and acute onset of diabetes. However, the association of the events with the steroid is not definite.Authors' conclusionsThere is insufficient evidence to recommend steroids for symptom control in infectious mononucleosis. There is a lack of research on the side effects, including potential adverse effects or long‐term complications.Plain Language SummarySteroids for short‐term symptom control in infectious mononucleosis (glandular fever)Glandular fever (infectious mononucleosis) is an infection carried in the saliva. Some people have no symptoms and young adults more commonly suffer symptomatic glandular fever. Common symptoms include fever, sore throat and swollen lymph nodes. The severity and duration of symptoms varies; a few people develop breathing difficulties due to swelling at the back of the throat and other complications requiring hospitalisation. Symptoms can last for months (it is a risk factor for chronic fatigue syndrome). Symptom relief and rest are commonly recommended treatments.This review identified four trials that compared the effectiveness of a steroid for short‐term symptom control in glandular fever to a placebo and three other trials that used a combination of steroid and a antiviral drug. In total they included 362 participants. Steroid treatment provided relief from sore throat in the short‐term (over 12 hours), in combination with an antiviral drug benefit was apparent at two to four days. However, these findings are limited because they were assessed in only one or two trials. Evidence of the effectiveness of steroids for other symptoms of glandular fever, or in combination with an antiviral drug, were less clear. We are unsure of adverse events from using steroids.

The Neurotoxic Effects of 2-Nitropropane on Nerve Conduction are Reversible, In Vitro

In general, the scientific evidence points to organic solvents as substances capable of affecting the nervous system, both central and peripheral level. The aim was to measure the effect of 2-nitropropane on the sciatic nerve of the frog in vitro . We found significant effects on parameters such as nerve conduction velocity, amplitude and duration of the compound action potential, and nerve impulse conduction. The importance of our results is that there was a reversible behavior simulating the effect of the anesthetics used in medical practice. Due to the depressive effect shown by this solvent we strongly recommend health surveillance of those who are in constant exposure to organic solvents and the use of personal protective equipment indicated in the corresponding safety sheets to manipulate these xenobiotics.

19 Drug evaluation in cardiomyocytes derived from human induced pluripotent stem cells carrying a Long QT Syndrome type 2 mutation

BackgroundCongenital Long QT Syndromes (LQTS) are associated with prolonged ventricular repolarisation and sudden cardiac death. Limitations to existing clinical therapeutic management strategies prompted us to develop a novel human in...

Expression and differential distribution of the shaker-related voltage-gated potassium channel family (KV1.x) in human hippocampus and neocortex

Background All excitable cells express voltage-gated potassium (KV) channels; in neurons they play an essential role in setting the resting membrane potential, controlling the firing frequency and duration of action potentials, and modulate neurotransmitter release. Due to this critical function as regulators of neuronal excitability, mutations and/or deletions in potassium channel subunit genes are associated with diverse clinical phenotypes (channelopathies), including seizure or movement disorders in both humans and animals. Additionally, voltage-gated potassium channels might play a crucial role in neurodegenerative and psychiatric disorders. For this reason, a better understanding of the occurrence and specific distribution of voltagegated potassium channels would be highly necessary. Several members of the KV1 subfamily have been found, but only KV1.1, KV1.2, KV1.4 and KV1.6 are widely expressed in the CNS in both human and rodent brain. However, unlike to rodents, little is known regarding the regional localization of these four members of the KV1 subfamily in human brain. Therefore we investigated, for the first time, the distribution of these four KV1 channel subtypes in human neocortex and hippocampus, which are known for their vulnerability to epilepsy and their importance for learning, memory and cognitive processes.

Co-Transplantation of Olfactory Ensheathing Cells from Mucosa and Bulb Origin Enhances Functional Recovery after Peripheral Nerve Lesion

Olfactory ensheathing cells (OECs) represent an interesting candidate for cell therapy and could be obtained from olfactory mucosa (OM-OECs) or olfactory bulbs (OB-OECs). Recent reports suggest that, depending on their origin, OECs display different functional properties. We show here the complementary and additive effects of co-transplanting OM-OECs and OB-OECs after lesion of a peripheral nerve. For this, a selective motor denervation of the laryngeal muscles was performed by a section/anastomosis of the recurrent laryngeal nerve (RLN). Two months after surgery, recovery of the laryngeal movements and synkinesis phenonema were analyzed by videolaryngoscopy. To complete these assessments, measure of latency and potential duration were determined by electrophysiological recordings and myelinated nerve fiber profiles were defined based on toluidine blue staining. To explain some of the mechanisms involved, tracking of GFP positive OECs was performed. It appears that transplantation of OM-OECs or OB-OECs displayed opposite abilities to improve functional recovery. Indeed, OM-OECs increased recuperation of laryngeal muscles activities without appropriate functional recovery. In contrast, OB-OECs induced some functional recovery by enhancing axonal regrowth. Importantly, co-transplantation of OM-OECs and OB-OECs supported a major functional recovery, with reduction of synkinesis phenomena. This study is the first which clearly demonstrates the complementary and additive properties of OECs obtained from olfactory mucosa and olfactory bulb to improve functional recovery after transplantation in a nerve lesion model.

Role of a Tetraethylammonium-Sensitive Component of Potassium Currents in High-Frequency Tonic Impulsation Generated by Rat Retinal Ganglion Cells

Using the voltage/current clamp technique in the whole-cell configuration, we studied the role of the highly tetraethylammonium (TEA) -sensitive component of integral potassium current in the generation of high-frequency tonic impulsation by rat retinal ganglion cells (RGCs). Application of 0.5 mM TEA led to a decrease in the frequency of evoked tonic impulsation by RGCs by 63% (from 55 ± 10 sec–1 in the control to 26 ± 5 sec–1 in the presence of the blocker; n = 11). In this case, the duration of single action potentials at the level of 50% their amplitude increased by 64% (from 1.1 ± 0.1 to 1.8 ± 0.1 msec; n = 11), the rate of repolarization decreased by 54% (from −101 ± 9 to −46 ± 5 mV/msec; n = 11), and the amplitude of afterhyperpolarization dropped by 62% (from −16 ± 2 to −6 ± 2 mV; n = 11). Upon the action of 0.5 mM TEA, the amplitude of the integral potassium current in RGCs decreased; the current component sensitive to the above blocker was equal to 0.41 ± 0.05 nA (n = 6), while the respective value in the control was 1.62 ± 0.14 nA (n = 12). Thus, a moderate (on average, by 25%) decrease in the amplitude of the above potassium current significantly influenced the characteristics of impulse activity generated by RGCs. The TEA-sensitive component of the current was similar to the Kv3.1/Kv3.2 potassium current described earlier. The obtained data are indicative of the key role of the highly TEA-sensitive component of the potassium current (passed probably via Kv3.1/Kv3 channels) in high-frequency tonic activity generated by RGCs.

P11.8 Direct muscle stimulation versus composed motor action potential (CMAP) duration for the diagnosis of critical illness “neuromyopathy”: evaluation of sensitivity and specificity

P11.8 Direct muscle stimulation versus composed motor action potential (CMAP) duration for the diagnosis of critical illness “neuromyopathy”: evaluation of sensitivity and specificity