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MEP
Terms modified by MEP Selected AbstractsMulti-Agent Distributed Coordination of Project Schedule ChangesCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2003Keesoo Kim This article presents the design and implementation of a multi-agent system called Distributed Subcontractor Agent System (DSAS), which consists of multiple subcontractor agents, multiple Graphic User Interfaces (GUIs), and an Agent Message Router. In the DSAS, subcontractors interact with their software agents to evaluate the impact of changes, simulate decisions, and get the negotiation results that they need to reschedule the project. This also presents the design and results of DSAS charrette tests, which demonstrated that DSAS produces the lower-cost results faster than manual centralized processes. DSAS can be useful for other domains, such as Mechanical, Electrical, and Plumbing (MEP) coordination and workspace management, if the appropriate agents are designed. [source] More power to the European Parliament?ECONOMIC POLICY, Issue 35 2002Abdul G. Noury SUMMARY Many observers have expressed scepticism about granting more power to the European Parliament. The sceptics believe that Members of the European Parliament (MEPs) do not vote in a disciplined way and that they vote more often with their country group than with their European Party. Using a unique database consisting of all roll call votes by each individual MEP between 1989 and 1999 (over 6000 votes by over 1000 different MEPs), we show that the sceptics are wrong. Our data shows clearly that MEPs vote more along party lines than along country lines. Party cohesion is comparable to that of the US Congress and is increasing over time whereas country cohesion is low and declining. In short, politics in the European Parliament generally follows the traditional left,right divide that one finds in all European nations. These findings are valid across issues, even on issues like the structural and cohesion funds where one would expect country rather than party cohesion. In votes where the EP has the most power , those held under the so-called co-decision procedure , MEPs participate more and are more party-cohesive. In our opinion, this unique empirical analysis provides grounds for justifying a generalization of the co-decision procedure. [source] Magnetically evoked motor potentials in demyelinating and axonal polyneuropathy: a comparative studyEUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2000H. Takada We investigated the value of magnetically evoked motor potentials (MEPs) for the differentiation of demyelinating and axonal polyneuropathies. The study population comprised 107 patients, with polyneuropathy verified by electromyography (EMG) and nerve conduction study (NCS), who had also been examined by means of MEP. MEPs were evoked by magnetic stimulation of the cortex and the spinal roots and were recorded from three upper limb muscles and two lower limb muscles bilaterally. From the EMG/NCS results 53 patients were characterized as having primary demyelination (demyelinating patients) and 54 as having axonal involvement (axonal patients). Demyelinating patients were classified as acute (acute inflammatory demyelinating polyradiculoneuropathy: AIDP ) or chronic (chronic inflammatory demyelinating polyradiculoneuropathy: CIDP ) according to the duration of illness. A series of indices were calculated from MEP results. One demyelinating patient and two axonal patients had normal MEPs. The MEPs of the demyelinating patients showed significantly longer peripheral conduction times, larger interside differences and lower amplitudes than the axonal patients. The central conduction index and the amplitudes upon cortical stimulation were significantly higher in patients with CIDP than in those with AIDP. Peripheral conduction time prolonged by more than 85% in at least one of the 10 muscles studied or a peripheral conduction index of above 9.4 were pathognomonic for demyelination . By combining all criteria 75% of the patients could be categorized as CIDP vs. AIDP in accordance with the EMG/NCS diagnosis. Likewise, 83% were categorized correctly as demyelinating versus axonal according to the EMG/NCS data. [source] Functional specificity of human premotor,motor cortical interactions during action selectionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2007Jacinta O'Shea Abstract Functional connections between dorsal premotor cortex (PMd) and primary motor cortex (M1) have been revealed by paired-pulse transcranial magnetic stimulation (TMS). We tested if such connections would be modulated during a cognitive process (response selection) known to rely on those circuits. PMd,M1 TMS applied 75 ms after a cue to select a manual response facilitated motor-evoked potentials (MEPs). MEPs were facilitated at 50 ms in a control task of response execution, suggesting that PMd,M1 interactions at 75 ms are functionally specific to the process of response selection. At 100 ms, PMd,M1 TMS delayed choice reaction time (RT). Importantly, the MEP (at 75 ms) and the RT (at 100 ms) effects were correlated in a way that was hand-specific. When the response was made with the M1-contralateral hand, MEPs correlated with slower RTs. When the response was made with the M1-ipsilateral hand, MEPs correlated with faster RTs. Paired-pulse TMS confined to M1 did not produce these effects, confirming the causal influence of PMd inputs. This study shows that a response selection signal evolves in PMd early during the reaction period (75,100 ms), impacts on M1 and affects behaviour. Such interactions are temporally, anatomically and functionally specific, and have a causal role in choosing which movement to make. [source] Differences between the effects of three plasticity inducing protocols on the organization of the human motor cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2006Karin Rosenkranz Abstract Several experimental protocols induce lasting changes in the excitability of motor cortex. Some involve direct cortical stimulation, others activate the somatosensory system and some combine motor and sensory stimulation. The effects usually are measured as changes in amplitude of the motor-evoked-potential (MEP) or short-interval intracortical inhibition (SICI) elicited by a single or paired pulses of transcranial magnetic stimulation (TMS). Recent work has also tested sensorimotor organization within the motor cortex by recording MEPs and SICI during short periods of vibration applied to single intrinsic hand muscles. Here sensorimotor organization is focal: MEPs increase and SICI decreases in the vibrated muscle, whilst the opposite occurs in neighbouring muscles. In six volunteers we compared the after effects of three protocols that lead to lasting changes in cortical excitability: (i) paired associative stimulation (PAS) between a TMS pulse and an electrical stimulus to the median nerve; (ii) motor practice of rapid thumb abduction; and (iii) sensory input produced by semicontinuous muscle vibration, on MEPs and SICI at rest and on the sensorimotor organization. PAS increased MEP amplitudes, whereas vibration changed sensorimotor organization. Motor practice had a dual effect and increased MEPs as well as affecting sensorimotor organization. The implication is that different protocols target different sets of cortical circuits. We speculate that protocols that involve repeated activation of motor cortical output lead to lasting changes in efficacy of synaptic connections in output circuits, whereas protocols that emphasize sensory inputs affect the strength of sensory inputs to motor circuits. [source] Isolation of the dxr gene of Zymomonas mobilis and characterization of the 1-deoxy- D -xylulose 5-phosphate reductoisomeraseFEMS MICROBIOLOGY LETTERS, Issue 1 2000Sigrid Grolle Abstract The gene encoding the second enzyme of the 2C -methyl- D -erythritol 4-phosphate (MEP) pathway for isopentenyl diphosphate biosynthesis, 1-deoxy- D -xylulose 5-phosphate (DXP) reductoisomerase, was cloned and sequenced from Zymomonas mobilis. The deduced amino acid sequence showed the highest identity (48.2%) to the DXP reductoisomerase of Escherichia coli. Biochemical characterization of the purified DXP reductoisomerase showed a strict dependence of the enzyme on NADPH and divalent cations (Mn2+, Co2+ or Mg2+). The enzyme is a dimer with a molecular mass of 39 kDa per subunit and has a specific activity of 19.5 U mg protein,1. Catalysis of the intramolecular rearrangement and reduction of DXP to MEP is competitively inhibited by the antibiotic fosmidomycin with a Ki of 0.6 ,M. [source] An Improved Preparation of D -Glyceraldehyde 3-Phosphate and Its Use in the Synthesis of 1-Deoxy- D -xylulose 5-PhosphateHELVETICA CHIMICA ACTA, Issue 9 2010Heng Li Abstract D -Glyceraldehyde 3-phosphate (=D -GAP; 2) was prepared by an improved chemical method (Scheme,2), and it was then employed to synthesize 1-deoxy- D -xylulose 5-phosphate (=DXP; 3) which is enzymatically one of the key intermediates in the MEP (4) terpenoid biosynthetic pathway (Scheme,1). The recombinant DXP synthase of Rhodobacter capsulatus was used to catalyze the condensation of D -glyceraldehyde 3-phosphate (2) and pyruvate (=2-oxopropanoate; 1) to produce the sugar phosphate 3 (Scheme,2). The simple two-step chemoenzymatic route described affords DXP (3) with more than 70% overall yield and higher than 95% purity. The procedure may also be used for the synthesis of isotope-labeled DXP (3) by using isotope-labeled pyruvate. [source] Intensity modulation of TMS-induced cortical excitation: Primary motor cortexHUMAN BRAIN MAPPING, Issue 6 2006Peter T. Fox Abstract The intensity dependence of the local and remote effects of transcranial magnetic stimulation (TMS) on human motor cortex was characterized using positron-emission tomography (PET) measurements of regional blood flow (BF) and concurrent electromyographic (EMG) measurements of the motor-evoked potential (MEP). Twelve normal volunteers were studied by applying 3 Hz TMS to the hand region of primary motor cortex (M1hand). Three stimulation intensities were used: 75%, 100%, and 125% of the motor threshold (MT). MEP amplitude increased nonlinearly with increasing stimulus intensity. The rate of rise in MEP amplitude was greater above MT than below. The hemodynamic response in M1hand was an increase in BF. Hemodynamic variables quantified for M1hand included value-normalized counts (VNC), intensity (z-score), and extent (mm3). All three hemodynamic response variables increased nonlinearly with stimulus intensity, closely mirroring the MEP intensity-response function. VNC was the hemodynamic response variable which showed the most significant effect of TMS intensity. VNC correlated strongly with MEP amplitude, both within and between subjects. Remote regions showed varying patterns of intensity response, which we interpret as reflecting varying levels of neuronal excitability and/or functional coupling in the conditions studied. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source] Direct ab initio dynamics calculations of the rate constants for the reaction of CHF2CF2OCH3 with ClINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2007Lei Yang A dual-level direct dynamics method is employed to reveal the dynamical properties of the reaction of CHF2CF2OCH3 (HFE-254pc) with Cl atoms. The optimized geometries and frequencies of the stationary points and the minimum energy path (MEP) are calculated at the B3LYP/6-311G(d,p) level by using GAUSSIAN 98 program package, and energetic information is further refined by the G3(MP2) method. Two H-abstraction channels have been identified. For the reactant CHF2CF2OCH3 and the two products, CHF2CF2OCH2 and CF2CF2OCH3, the standard enthalpies of formation are evaluated with the values of ,256.71 ± 0.88, ,207.79 ± 0.12, and ,233.43 ± 0.88 kcal/mol, respectively, via group-balanced isodesmic reactions. The rate constants of the two reaction channels are evaluated by means of canonical variational transition-state theory (CVT) including the small-curvature tunneling (SCT) correction over a wide range of temperature from 200 to 2000 K. The calculated rate constants agree well with the experimental data, and the Arrhenius expressions for the title reaction are fitted and can be expressed as k1 = 9.22 × 10,19 T2.06 exp(219/T), k2 = 4.45 × 10,14T0.90 exp(,2220/T), and k = 4.71 × 10,22 T3.20) exp(543/T) cm3 molecule,1 s,1. Our results indicate that H-abstraction from CH3 group is the main reaction pathway in the lower temperature range, while H-abstraction from CHF2 group becomes more competitive in the higher temperature range. © 2007 Wiley Periodicals, Inc. 39: 221,230, 2007 [source] Efficient power analysis for an irreversible Carnot heat engineINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2008Tamer Yilmaz Abstract In this paper, the finite-time thermodynamic optimization is carried out based on the efficient power criterion for an irreversible Carnot heat engine. The obtained results are compared with those obtained by using the maximum power (MP) and maximum power density (MPD) criteria. The optimal design parameters have been derived analytically, and the effect of the irreversibilities on the general and optimal performances is investigated. Maximizing the efficient power gives a compromise between power and efficiency. The results showed that the design parameter at the maximum efficient power (MEP) condition leads to more efficient engines than at the MP conditions and that the MEP criterion may have a significant power advantage with respect to the MPD criterion. Copyright © 2007 John Wiley & Sons, Ltd. [source] Fitting potential energy surface of reactive systems via genetic algorithmINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2006Wiliam Ferreira Da Cunha Abstract We present a new fitting of the Na+HF potential energy surface (PES) using a new optimization method based on genetic algorithm. Topology studies, such as isoenergetic contours and minimum energy path (MEP), show that the quality of this new PES is comparable to the best PES of literature. These facts suggest that this new approach can be used as a new tool to fit PES of reactive systems. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Theoretical study of the substituent effect on the intramolecular hydrogen bonds in di(4-hydroxycoumarin) derivativesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2006Tzvetan Mihaylov Abstract Geometry optimization of ortho -, meta -, and para -pyridyl-substituted di(4-hydroxycoumarin) [di(4-HC)] was performed with the density functional theory (DFT) [B3LYP/6-31G(d)] method. Two asymmetrical intramolecular OH,O hydrogen bonds (HBs) stabilized the structures. The calculated single HB energies varied from ,62.56 to ,47.53 kJ mol,1 and pointed to a relative strong hydrogen bond in the systems studied. The 2- and 6-pyridyl substituents produced the largest geometrical changes in di(4-hydroxycoumarin) fragment. The highest total HB energy was found for 2-pyridyl-substituted and the lowest one for 6-pyridyl-substituted di(4-hydroxycoumarin). The HB energy variations were confirmed with rotational barrier method calculations. Both steric and electrostatic factors were found to be responsible for the HB asymmetry in the compounds studied. According to the molecular electrostatic potential (MEP) calculations the most preferred reactive site for electrophilic attack of pyridyl-substituted di(4-hydroxycoumarin)s are the pyridine nitrogen and the carbonyl oxygens, followed by the hydroxyl oxygens. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Principal component analysis of the effects of wavefunction modification on the electrostatic potential of indoleINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2005Maíra A. Carvalho Abstract The molecular electrostatic potential (MEP) of the indole molecule was calculated in a three-dimensional grid in which the molecule was centered at the origin. To evaluate the dependence of MEP on the type of calculation, semiempirical, ab initio, and density functional theory methods with different basis sets were employed. The data matrix generated by these calculations was analyzed by principal component analysis (PCA). The appearance of outliers and the effect of wavefunction modifications such as the introduction of electron correlations and diffuse functions were highlighted by the use of PCA. The spatial localization of such effects around the molecule was possible from the loadings values associated with the graphical analysis of the grid points. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] Modeling and predicting binding affinity of phencyclidine-like compounds using machine learning methodsJOURNAL OF CHEMOMETRICS, Issue 1 2010Ozlem Erdas Abstract Machine learning methods have always been promising in the science and engineering fields, and the use of these methods in chemistry and drug design has advanced especially since the 1990s. In this study, molecular electrostatic potential (MEP) surfaces of phencyclidine-like (PCP-like) compounds are modeled and visualized in order to extract features that are useful in predicting binding affinities. In modeling, the Cartesian coordinates of MEP surface points are mapped onto a spherical self-organizing map (SSOM). The resulting maps are visualized using electrostatic potential (ESP) values. These values also provide features for a prediction system. Support vector machines and partial least-squares method are used for predicting binding affinities of compounds. Copyright © 2009 John Wiley & Sons, Ltd. [source] Stereoelectronic properties of spiroquinazolinones in differential PDE7 inhibitory activityJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2008Pankaj R. Daga Abstract A detailed computational study on a series of spiroquinazolinones showing phosphodiesterase 7 (PDE7) inhibitory activity was performed to understand the binding mode and the role of stereoelectronic properties in binding. Our docking studies reproduced the essential hydrogen bonding and hydrophobic interactions for inhibitors of this class of enzymes. The N1 proton of the quinazolinone scaffold was involved in H-bonding to an amide side chain of the conserved glutamine residue in the active site. The central bicyclic ring of the molecules showed hydrophobic and ,-stacking interactions with hydrophobic and aromatic amino acid residues, respectively, present in the PDE7 active site. The docked conformations were optimized with density functional theory (DFT) and DFT electronic properties were calculated. Comparison of molecular electrostatic potential (MEP) plots of inhibitors with the active site of PDE7 suggested that the electronic distribution in the molecules is as important as steric factors for binding of the molecules to the receptor. The hydrogen bonding ability and nucleophilic nature of N1 appeared to be important for governing the interaction with PDE7. For less active inhibitors (pIC50 < 6.5), the MEP maximum at N1 of the spiroquinazolinone ring was high or low based on the electronic properties of the substituents. All the more active molecules (pIC50 > 6.5) had MEP highest at N3, not N1. Efficient binding of these inhibitors may need some rearrangement of side chains of active-site residues, especially Asn365. This computational modeling study should aid in design of new molecules in this class with improved PDE7 inhibition. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008 [source] Improved intermolecular force field for molecules containing H, C, N, and O atoms, with application to nucleoside and peptide crystalsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 11 2001Donald E. Williams Abstract A new intermolecular force field for nitrogen atoms in organic molecules was derived from a training dataset of 76 observed azahydrocarbon crystal structures and 11 observed heats of sublimation. The previously published W99 force field for hydrogen, carbon, and oxygen was thus extended to include nitrogen atoms. Nitrogen atoms were divided into four classes: N(1) for triply bonded nitrogen, N(2) for nitrogen with no bonded hydrogen (except the triple bonded case), N(3) for nitrogen with one bonded hydrogen, and N(4) for nitrogen with two or more bonded hydrogens. H(4) designated hydrogen bonded to nitrogen. Wavefunctions of 6-31g** quality were calculated for each molecule and the molecular electric potential (MEP) was modeled with net atomic and supplementary site charges. Lone pair electron charge sites were included for nitrogen atoms where appropriate, and methylene bisector charges were used for CH2 and CH3 groups when fitting the MEP. XH bond distances were set to standard values for the wave function calculation and then foreshortened by 0.1 Å for the MEP and force field fitting. Using the force field optimized to the training dataset, each azahydrocarbon crystal structure was relaxed by intermolecular energy minimization. Predicted maximum changes in unit cell edge lengths for each crystal were 3% or less. The complete force field for H, C, N, and O atoms was tested by intermolecular energy relaxation of nucleoside and peptide molecular crystals. Even though these molecules were not included in any of the training datasets for the force field, agreement with their observed crystal structures was very good, with predicted unit cell edge shifts usually less than 2%. These tests included crystal structures of representatives of all eight common nucleosides found in DNA and RNA, 15 dipeptides, four tripeptides, two tetrapeptides, and a pentapeptide with two molecules in the asymmetric unit. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1154,1166, 2001 [source] Expression of cytokeratin subtypes in intraepidermal malignancies: a guide for differentiationJOURNAL OF CUTANEOUS PATHOLOGY, Issue 8 2006Figen Aslan Background:, Among intraepidermal malignancies of epithelial origin, Bowen's disease, bowenoid actinic keratosis (BAK), intraepidermal malignant eccrine poroma (MEP), and Paget's disease may pose diagnostic difficulties. Methods:, Histologic features and immunohistochemical profiles of 24 cases of Bowen's disease, 21 cases of BAK, 18 cases of intraepidermal MEP, and 11 cases of Paget's disease were analyzed. Results:, Using multivariate logistic regression test, multinuclear giant cells and solar degeneration were found to be the only histologic parameters of diagnostic help. On the other hand, a widespread positive reaction for CK 5/8, CK 7, CK 19, and negative reaction for CK 10, was a helpful feature in the differentiation of Paget's disease from Bowen's disease and BAK. The widespread and strong expression of CK 10 was seen in almost all cases of Bowen's disease in contrast to BAK. The widespread expression of CK 5/8 and CK 7, and negative reaction for CK 10, was in favor of Paget's disease, compared to intraepidermal MEP. On the other hand, widespread expression of CK 19 was a common finding in intraepidermal MEP, in contrast to Bowen's disease. Conclusion:, An immunohistochemical panel may provide significant hints on the differentiation of common intraepidermal malignancies, especially in problematic cases. [source] Synthesis and stability study of dental monomers containing methacrylamidoethyl phosphonic acidsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2007Xiaoming Xu Abstract Three new dental monomers containing methacrylamidoethyl phosphonic acids were synthesized. The structures of the synthesized monomers were determined with electrospray mass spectrometry (ESMS), Fourier transform infrared, and NMR. The hydrolytic stabilities of the synthesized monomers and a commercial monomer, 2-methacryloyloxyethyl phosphoric acid (MEP; used as a control), were studied with flow injection (FI)/ESMS, 1H NMR, and 31P NMR analysis of a CD3OD/D2O (4:1 v/v) solution of each monomer before and after storage at 60 °C for 2 months. The 1H NMR and 31P NMR chemical shifts of the monomers 2-methacrylamidoethylphosphonic acid (I) and N,N,-[4,4,-(propane-2,2-diyl)-bis(phenoxy-2-hydroxypropyl)]-bis(2-methacrylamidoethylphosphonic acid) (II) showed little change after storage at 60 °C for 2 months, but those of MEP changed significantly. FI/ESMS also showed that MEP was nearly completely decomposed, whereas monomers I and II remained largely intact. MEP could react with H2ZrF6 to form ternary zirconium fluoride complexes that were partially soluble in methanol, but all the monomers containing phosphonic acids formed precipitates. This study demonstrates that ESMS is a more sensitive and effective method than NMR for studying the hydrolytic stability or degradation of dental monomers. The new monomers containing methacrylamidoethyl phosphonic acids have higher hydrolytic stability than methacrylate phosphate monomers and may be used in dental bonding agents and other dental materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 99,110, 2007 [source] The Role of Pre-collegiate Partnership Programs in Environments Ambivalent about Affirmative Action: Reflections and Outcomes from an Early ImplementationJOURNAL OF SOCIAL ISSUES, Issue 3 2005Geoffrey Maruyama Preparing underrepresented students for college success though pre-collegiate partnership programs is one alternative to affirmative action programs. This article describes the Multicultural Excellence Program (MEP), a partnership program between an urban school district and 22 four-year higher education institutions. MEP, begun in 1987, targets 7th,12th-grade students from groups historically underrepresented in higher education. It helps them plan how to prepare themselves for continuing on to a four-year college. Analyses evaluating program effectiveness examined outcomes of over 4,000 secondary students and 243 college students. Despite substantial turnover, particularly at transition points, MEP has been very successful in enrolling its high school graduates immediately in four-year colleges. Although many MEP students have thrived in college, a smaller proportion has struggled. [source] ANTI-SULFATIDE IgM ANTIBODIES DETECTED IN A PATIENT DIAGNOSIS OF MOTOR NEURON DISEASEJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2002Article first published online: 11 MAR 200 D'Avino C., Del Corona A., Bacci A., Calabrese R., Siciliano G. Department of Neuroscience-Clinical Neurology-University of Pisa-Italy Case report. The patient, a 66-year-old man with a 5-year diagnosis of diabetes mellitus, in Sep. 2000 started complaining of language disturbances as rhinolalia. In Jan. 2001, because of generalized fatigue and difficulties in walking, he was hospitalized in Internal Medicine and a diagnosis of diabetic angiopathy and neuropathy was made. Since discharge patient clinical conditions gradually deteriorated and a neurological evaluation showed tongue atrophy, dysarthria, dysphagia, fasciculations in the four limbs, increased deep tendon reflexes with bilateral foot clonus and paraparetic spastic deambulation. He underwent spinal MRI that showed mild arthrosic abnormalities in cervical spinal cord and limb EMG that showed denervation spontaneous activity with neurogenic MUAP modifications, with normal sensory and motor conduction velocity. MEP showed bilateral pyramidal track involvement. A significantly increased anti-sulphatide IgM antibodies titer (1:32,000) in the serum was detected. The diagnosis at discharge was "probable motor neuron disease" and the patient is under riluzole therapy at the moment. Discussion. Anti-sulfatide IgM antibodies are currently associated with several subtypes of peripheral neuropathy. In most cases it is a chronic dysimmune sensory or sensorimotor neuropathy in which electrophysiological and morphological studies are usually con- sistent with a predominant demyelination frequently associated with prominent axonal loss. Although rare, an association between motor neuron disease and IgM anti-sulfatide has been described in a recent paper by Latov and coworkers that reviewed electrophysiologic, morphologic and laboratory data of 25 patients with elevated antisulfatide antibodies. It seems interesting to follow-up the clinical course of the patient, the response to therapy and its correlation to antibodies titer, while the opportunity of high dose IVIg therapy is under discussion at the moment. [source] Dopamine agonists restore cortical plasticity in patients with idiopathic restless legs syndrome,MOVEMENT DISORDERS, Issue 5 2009Vincenzo Rizzo MD Abstract In the present work, we aimed at assessing whether patients with idiopathic restless legs syndrome (RLS) showed alterations of sensory-motor plasticity, an indirect probe for motor learning, within the motor cortex (M1). Previous findings suggest that learning in human M1 occurs through LTP-like mechanisms. To test our hypothesis, we employed the paired associative stimulation (PAS) protocol by transcranial magnetic stimulation (TMS), which is able to induce LTP-like effects in the motor cortex of normal subjects. Twelve patients with idiopathic RLS and 10 age- and sex-matched control subjects were recruited. PAS protocol consisted of 0.05 Hz electrical median nerve stimulation (90 stimuli), paired with 0.05 Hz TMS (90 stimuli) over the hot spot for stimulating the abductor pollicis brevis (APB) muscle given 25 milliseconds after the onset of the electrical stimulus. Corticospinal excitability recorded in APB muscle, as indexed by MEP obtained after single stimulus, was tested before and up to 30 minutes after PAS protocol. Eight of 12 patients were studied before and after 4 weeks of dopaminergic treatment. PAS protocol increased significantly corticospinal excitability as long as 30 minutes in healthy subjects. On the contrary, PAS protocol did not change the amplitude of MEPs in patients with idiopathic RLS without treatment. PAS associative plasticity was restored after 4 weeks of dopaminergic treatment. Our data demonstrated that associative sensory-motor plasticity, an indirect probe for motor learning, is impaired in idiopathic RLS patients but may be reverted to normal after dopaminergic treatment. © 2008 Movement Disorder Society [source] Asymmetric corticomotor excitability correlations in early Parkinson's diseaseMOVEMENT DISORDERS, Issue 11 2007Allan D. Wu MD Abstract We studied corticomotor excitability (CE) between the more and less affected sides in early Parkinson's disease (PD) patients using transcranial magnetic stimulation (TMS). Sixteen-PD patients within the first 3 years of diagnosis were studied with single-pulse TMS over each motor cortex with intensities from 40% to 100% stimulator output. Active motor evoked potentials (MEP) and cortical silent period durations (CSP) were recorded, fitted with sigmoid curves, summarized as maximal MEP/CSP, maximal MEP/CSP slope, and intensity where MEP/CSP is half-maximal (MEP/CSP-Int50), and correlated with Unified Parkinson's Disease Rating Scale scores (UPDRS). On the more affected side, higher (worse) UPDRS scores were correlated with shorter maximal CSP (r = ,0.51, P = 0.046). On the less affected side, higher UPDRS scores were correlated with higher MEP-Int50 (r = 0.51, P = 0.043) and CSP-Int50 (r = 0.54, P = 0.029). For the less affected side, altered CE, as indexed by higher MEP or CSP-Int50 intensities, may contribute to early clinical symptoms. On the more affected side, increases in CE, indexed by shorter CSP, may account for a greater proportion of PD symptoms. These findings are consistent with an evolution of neurophysiologic correlates in early PD patients from a less to more symptomatic state. © 2007 Movement Disorder Society [source] Impaired motor imagery in patients with essential tremor: A case control studyMOVEMENT DISORDERS, Issue 4 2007Yew-Long Lo MD Abstract Motor imagery (MI), which refers to the process of mental representation of movements, has not been studied in patients with essential tremor (ET). We investigated the presence of impaired MI in ET patients compared with healthy controls. A group of drug-naive and nondemented ET patients and age-matched controls were studied using transcranial magnetic stimulation, while they were specifically instructed to try and imagine themselves performing two motor tasks. The various clinical and electrophysiological variables were evaluated and compared. Repeated measures ANOVA demonstrated a significant difference between ET patients and controls with respect to mean motor-evoked potential (MEP) amplitudes (F(1,38) = 31.92, P < 0.005) during MI. The process of MI effectively facilitated MEP amplitude in controls but not in ET patients, regardless of side of stimulation or motor tasks. We provide evidence to demonstrate impairment of MI in a group of ET patients compared with healthy controls. The basis for this novel finding is unclear, and further studies are warranted to determine whether it is related to cerebellar or motor cortical dysfunction. © 2007 Movement Disorder Society [source] Impaired heteronymous somatosensory motor cortical inhibition in dystoniaMOVEMENT DISORDERS, Issue 11 2003Laura Bertolasi MD Abstract A typical pathophysiological abnormality in dystonia is cocontraction of antagonist muscles, with impaired reciprocal inhibitory mechanisms in the spinal cord. Recent experimental data have shown that inhibitory interactions between antagonist muscles have also a parallel control at the level of the sensorimotor cortex. The aim of this work was to study heteronymous effects of a median nerve stimulus on the corticospinal projections to forearm muscles in dystonia. We used the technique of antagonist cortical inhibition, which assesses the conditioning effect of median nerve afferent input on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in ipsilateral forearm extensor muscles at rest. Nine healthy subjects and 10 patients with torsion dystonia participated in the study. MEPs and somatosensory evoked potentials were normal in patients. In healthy subjects, median nerve stimulation at 15- to 18-msec intervals inhibited the test MEPs in forearm extensors. In dystonic patients, median nerve stimulation delivered at the same conditioning,test intervals elicited significantly less inhibition of the test MEP. On the whole, these data suggest an impaired sensory,motor integration in dystonia and, more specifically, the decreased antagonistic cortical inhibition could suggest that functional interactions between antagonist muscles are primarily impaired at the cortical level. © 2003 Movement Disorder Society [source] Altered corticomotor representation in patients with Parkinson's diseaseMOVEMENT DISORDERS, Issue 8 2003Florian A. Kagerer PhD Abstract In 6 patients with Parkinson's disease (PD) and 6 age-matched controls, transcranial magnetic stimulation was applied at 56 regions over the motor cortex and premotor cortex of each hemisphere, with the first dorsal interosseous (FDI) muscle of both hands activated at 15% maximum voluntary contraction during stimulation. For each site, motor evoked potential (MEP) landmarks were recovered, including MEP amplitude, MEP onset latency, and silent period duration. Scaled MEP amplitudes were used to construct individual cortical maps of the FDI muscles. The maps revealed an anterior displacement of the muscle representation in PD patients. This anterior shift over motor cortical areas may reflect increased contributions of corticocortical connections between motor cortex and premotor cortical areas, possibly enhanced by the visual feedback aspect of the task. These alterations may reflect adaptations to the impairments in striatocortical circuits in PD. © 2003 Movement Disorder Society [source] Orthostatic tremor arises from an oscillator in the posterior fossaMOVEMENT DISORDERS, Issue 2 2001Y.R. Wu MD Abstract We tested the hypotheses that orthostatic tremor is generated by a central oscillator and that the tremor is expressed through spinal Ib interneurons. Six patients with orthostatic tremor were examined. The tremor was reset by electrical stimulation over the posterior fossa at intensities that were below the threshold for a motor evoked potential (MEP) but was not reset by transcranial magnetic stimulation over the motor cortex that did produce an MEP. It is argued that the oscillator involves the cerebellum or brainstem. The inhibition of voluntary EMG produced by stimulation over tendons, which has been attributed to effects from Golgi tendon organs (GTO), was not modulated in synchrony with the tremor. We were unable to demonstrate, therefore, that the tremor is expressed through GTO interneurons with this method. © 2001 Movement Disorder Society. [source] The minimum evolution problem: Overview and classificationNETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2009Daniele Catanzaro Abstract Molecular phylogenetics studies the hierarchical evolutionary relationships among organisms by means of molecular data. These relationships are typically described by means of weighted trees, or phylogenies, whose leaves represent the observed organisms, internal vertices the intermediate ancestors, and edges the evolutionary relationships between pairs of organisms. Molecular phylogenetics provides several criteria for selecting one phylogeny from among plausible alternatives. Usually, such criteria can be expressed in terms of objective functions, and the phylogenies that optimize them are referred to as optimal. One of the most important criteria is the minimum evolution (ME) criterion, which states that the optimal phylogeny for a given set of organisms is the one whose sum of edge weights is minimal. Finding the phylogeny that satisfies the ME criterion involves solving an optimization problem, called the minimum evolution problem (MEP), which is notoriously -Hard. This article offers an overview of the MEP and discusses the different versions of it that occur in the literature. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009 [source] Abnormal somatosensory evoked potentials in two patients with conversion disorderPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 2 2004KAZIM M. YAZICI md Abstract, On clinical grounds, somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) are currently used to discriminate between hysterical and neurological conditions. The present paper reports on two patients with severe gait disturbance who had the near-total absence of SEP responses on the scalp during the symptomatic period, which normalized after recovery. These findings, along with others, may shed light on the brain correlates of conversion phenomena. [source] Human motor associative plasticity induced by paired bihemispheric stimulationTHE JOURNAL OF PHYSIOLOGY, Issue 19 2009Satoko Koganemaru Paired associative stimulation (PAS) is an effective non-invasive method to induce human motor plasticity by the repetitive pairing of peripheral nerve stimulation and transcranial magnetic stimulation (TMS) at the primary motor cortex (M1) with a specific time interval. Although the repetitive pairing of two types of afferent stimulation might be a biological basis of neural plasticity and memory, other types of paired stimulation of the human brain have rarely been studied. We hypothesized that the repetitive pairing of TMS and interhemispheric cortico-cortical projection or paired bihemispheric stimulation (PBS), in which the right and left M1 were serially stimulated with a time interval of 15 ms, would produce an associative long-term potentiation (LTP)-like effect. In this study, 23 right-handed healthy volunteers were subjected to a 0.1 Hz repetition of 180 pairings of bihemispheric TMS, and physiological and behavioural measures of the motor system were compared before, immediately after, 20 min after and 40 min after PBS intervention. The amplitude of the motor evoked potential (MEP) induced by the left M1 stimulation and its input,output function increased for up to ,20 min post-PBS. Fine finger movements were also facilitated by PBS. Spinal excitability measured by the H-reflex was insensitive to PBS, suggesting a cortical mechanism. The associative LTP-like effect induced by PBS was timing dependent, occurring only when the interstimulus interval was 5,25 ms. These findings demonstrate that using PBS in PAS can induce motor cortical plasticity, and this approach might be applicable to the rehabilitation of patients with motor disorders. [source] Time-varying changes in corticospinal excitability accompanying the triphasic EMG pattern in humansTHE JOURNAL OF PHYSIOLOGY, Issue 3 2000Colum D. MacKinnon 1Nine healthy subjects performed single rapid wrist movements from neutral to targets at 20 deg of flexion or extension in response to an auditory cue. Surface EMG was recorded from the wrist flexors and extensors together with wrist position. Movements in both directions were characterised by the usual triphasic pattern of EMG activity in agonist (AG1), antagonist (ANTAG) and again in agonist (AG2) muscles. 2Single pulses of transcranial magnetic stimulation (TMS) were applied over the motor cortex at an intensity of 80 % of resting threshold at random times between 80 and 380 ms after the cue. We measured the peak-to-peak amplitude of the evoked motor potential (MEP) and the integrated EMG (IEMG) activity that preceded the MEP. In a separate set of experiments H reflexes were elicited in the wrist flexors instead of MEPs. 3MEP amplitudes in the agonist muscle increased by an average of 10 ± 8 ms (range ,1 to 23 ms) prior to the onset of the AG1 burst and were associated with an increase of over sevenfold in the MEP:IEMG ratio, irrespective of movement direction. Agonist H reflex amplitudes were linearly related to, and increased at the same time as, changes in agonist IEMG. 4The principal ANTAG burst was not preceded by an increase in the antagonist muscle MEP:IEMG ratio. No relationship was found between the amplitude of the antagonist H reflexes and the preceding antagonist IEMG. 5Five subjects showed an increase in the MEP:IEMG ratio preceding and during the initial part of the AG2 burst. 6Our method of analysis shows that changes in motor cortical excitability mediating the initiation of movement occur much closer to the onset of EMG activity (less than 23 ms) than the 80,100 ms lead time previously reported. The lack of such changes before the onset of the ANTAG burst suggests that this may be initiated by a different, perhaps subcortical, mechanism. [source] | ||||||||||||||||||||||