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V2
Kinds of V2 Terms modified by V2 Selected AbstractsTime evolution of cholesteric fingers of the second species in an electric fieldCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2009S. Pirkl Abstract Different growth modes of isolated cholesteric fingers of the second species (CF-2) in an electric field at voltages near a coexistence line (V2) between cholesteric and nematic mesophases are in detail described. Videomicroscopy and computer image analysis were used for investigation of the pattern in polarized light. It is shown how a drift, a lengthening and a shape of fingers depend on the voltage at which the growth sets in and three typical scenarios are distinguished. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Vanadium Carbonyl Nitrosyl Compounds: The Carbonyl Nitrosyl Chemistry of an Oxophilic Early Transition MetalEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2009Hongyan Wang Abstract The vanadium carbonyl nitrosyl compounds V(NO)(CO)n (n = 5, 4, 3) and V2(NO)2(CO)n (n = 9, 8, 7) have been examined by density functional theory in order to assess the effect of the oxophilicity of vanadium on its metal carbonyl nitrosyl chemistry. The expected octahedral structure for the experimentally known, but surprisingly unstable, V(NO)(CO)5, is confirmed by DFT. The optimized structures of the unsaturated derivatives V(NO)(CO)4 and V(NO)(CO)3 can be derived from the octahedral V(NO)(CO)5 structure by loss of one or two carbonyl groups, respectively. This leads to anearly square-planar predicted structure for V(NO)(CO)3. The lowest energy structures for the binuclear derivatives V2(NO)2(CO)n (n = 9, 8, 7) have exclusively two-electron donor carbonyl groups and three-electron donor linear nitrosyl groups with metal,metal distances corresponding to the formal bond orders required for the favored 18-electron configurations. Bridging carbonyl groups appear to be preferred energetically over bridging nitrosyl groups in the V2(NO)2(CO)n structures in contrast to the similar carbonyl nitrosyl compounds of later transition metals. The saturated V2(NO)2(CO)9, with a relatively long V,V distance of 3.583 Ĺ (B3LYP) or 3.205 Ĺ (BP86), is thermodynamically unstable with respect to dissociation into V(NO)(CO)5 + V(NO)(CO)4.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Heteromodal connections supporting multisensory integration at low levels of cortical processing in the monkeyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005Céline Cappe Abstract While multisensory integration is thought to occur in higher hierarchical cortical areas, recent studies in man and monkey have revealed plurisensory modulations of activity in areas previously thought to be unimodal. To determine the cortical network involved in multisensory interactions, we performed multiple injections of different retrograde tracers in unimodal auditory (core), somatosensory (1/3b) and visual (V2 and MT) cortical areas of the marmoset. We found three types of heteromodal connections linking unimodal sensory areas. Visuo-somatosensory projections were observed originating from visual areas [probably the ventral and dorsal fundus of the superior temporal area (FSTv and FSTd), and middle temporal crescent (MTc)] toward areas 1/3b. Somatosensory projections to the auditory cortex were present from S2 and the anterior bank of the lateral sulcus. Finally, a visuo-auditory projection arises from an area anterior to the superior temporal sulcus (STS) toward the auditory core. Injections in different sensory regions allow us to define the frontal convexity and the temporal opercular caudal cortex as putative polysensory areas. A quantitative analysis of the laminar distribution of projecting neurons showed that heteromodal connections could be either feedback or feedforward. Taken together, our results provide the anatomical pathway for multisensory integration at low levels of information processing in the primate and argue against a strict hierarchical model. [source] Neuron,Glia Signaling in Trigeminal Ganglion: Implications for Migraine PathologyHEADACHE, Issue 7 2007Srikanth Thalakoti BS Objective.,The goal of this study was to investigate neuronal,glial cell signaling in trigeminal ganglia under basal and inflammatory conditions using an in vivo model of trigeminal nerve activation. Background.,Activation of trigeminal ganglion nerves and release of calcitonin gene-related peptide (CGRP) are implicated in the pathology of migraine. Cell bodies of trigeminal neurons reside in the ganglion in close association with glial cells. Neuron,glia interactions are involved in all stages of inflammation and pain associated with several central nervous system (CNS) diseases. However, the role of neuron,glia interactions within the trigeminal ganglion under normal and inflammatory conditions is not known. Methods.,Sprague,Dawley rats were utilized to study neuron,glia signaling in the trigeminal ganglion. Initially, True Blue was used as a retrograde tracer to localize neuronal cell bodies in the ganglion by fluorescent microscopy and multiple image alignment. Dye-coupling studies were conducted under basal conditions and in response to capsaicin injection into the TMJ capsule. S100B and p38 expression in neurons and glia were determined by immunohistochemistry following chemical stimulation. CGRP levels in the ganglion were measured by radioimmunoassay in response to capsaicin. In addition, the effect of CGRP on the release of 19 different cytokines from cultured glial cells was investigated by protein microarray analysis. Results.,In unstimulated control animals, True Blue was detected primarily in neuronal cell bodies localized in clusters within the ganglion corresponding to the V3 region (TMJ capsule), V2 region (whisker pad), or V1 region (eyebrow and eye). However, True Blue was detected in both neuronal cell bodies and adjacent glia in the V3 region of the ganglion obtained from animals injected with capsaicin. Dye movement into the surrounding glia correlated with the time after capsaicin injection. Chemical stimulation of V3 trigeminal nerves was found to increase the expression of the inflammatory proteins S100B and p38 in both neurons and glia within the V3 region. Unexpectedly, increased levels of these proteins were also observed in the V2 and V1 regions of the ganglion. CGRP and the vesicle docking protein SNAP-25 were colocalized in many neuronal cell bodies and processes. Decreased CGRP levels in the ganglion were observed 2 hours following capsaicin stimulation. Using protein microarray analysis, CGRP was shown to differentially regulate cytokine secretion from cultured trigeminal ganglion glia. Conclusions.,We demonstrated that activation of trigeminal neurons leads to changes in adjacent glia that involve communication through gap junctions and paracrine signaling. This is the first evidence, to our knowledge, of neuron,glia signaling via gap junctions within the trigeminal ganglion. Based on our findings, it is likely that neuronal,glial communication via gap junctions and paracrine signaling are involved in the development of peripheral sensitization within the trigeminal ganglion and, thus, are likely to play an important role in the initiation of migraine. Furthermore, we propose that propagation of inflammatory signals within the ganglion may help to explain commonly reported symptoms of comorbid conditions associated with migraine. [source] Effect of halothane on type 2 immobility-related hippocampal theta field activity and theta-on/theta-off cell dischargesHIPPOCAMPUS, Issue 1 2003Brian H. Bland Abstract Rats were studied in acute and chronic (freely moving) recording conditions during exposure to different levels of the volatile anesthetic halothane, in order to assess effects on hippocampal theta field activity in the chronic condition and on theta-related cellular discharges in the acute condition. Previous work has shown that the generation of hippocampal type 2 theta depends on the coactivation of cholinergic and GABAergic inputs from the medial septum. Based on these data and recent findings that halothane acts on interneuron GABAA receptors, we predicted that exposure of rats to subanesthetic levels would result in the induction of type 2 theta field activity. In the chronic condition, exposure to subanesthetic levels of halothane (0.5,1.0 vol %) was found to induce theta field activity during periods of immobility (type 2 theta) with a mean increase of 39% in amplitude (mV) compared to control levels during movement. The total percentage of signal power (V2) associated with peak theta frequencies (80% compared to control levels of 47%) was also increased by halothane. Over the whole range of administered halothane concentrations, theta field frequency progressively declined from a mean peak frequency of 6.5 ± 0.8 Hz at 0.5 vol % halothane to a mean peak frequency of 4.0 ± 1.8 Hz at 2.0 vol % halothane. Subsequent administration of a muscarinic cholinergic antagonist, atropine sulfate, selectively abolished all type 2 immobility-related theta field activity, while type 1 movement-related theta was still intact. At anesthetic levels (1.5,2.0 vol %) in acute experiments, hippocampal field activity spontaneously cycled between theta and large-amplitude irregular activity. Analysis of depth profiles in four experiments revealed they were identical to those previously described for rats under urethane anesthesia conditions. In addition, the discharge properties of 31 theta-related cells, classified as tonic and phasic theta-on and tonic and phasic theta-off cells, did not differ significantly from those described previously in rats anesthetized with urethane. These data provide further support for an involvement of GABAA receptors in the generation of hippocampal theta. Hippocampus 2003;13:38,47. © 2003 Wiley-Liss, Inc. [source] fMRI reveals that non-local processing in ventral retinotopic cortex underlies perceptual grouping by temporal synchronyHUMAN BRAIN MAPPING, Issue 6 2008Gideon P. Caplovitz Abstract When spatially separated objects appear and disappear in a synchronous manner, they perceptually group into a single global object that itself appears and disappears. We employed functional magnetic resonance imaging (fMRI) to identify brain regions involved in this type of perceptual grouping. Subjects viewed four chromatically-defined disks (one per visual quadrant) that flashed on and off. We contrasted %BOLD signal changes between blocks of synchronously flashing disks (Grouping) with blocks of asynchronously flashing disks (no-Grouping). Results: A region of interest analysis revealed %BOLD signal change in the Grouping condition was significantly greater than in the no-Grouping condition within retinotopic areas V2, V3, and V4v. Within a single quadrant of the visual field, the spatio-temporal information present in the image was identical across the two stimulus conditions. As such, the two conditions could not be distinguished from each other on the basis of the rate or pattern of flashing within a single visual quadrant. The observed results must therefore arise through nonlocal interactions between or within these retinotopic areas, or arise from outside these retinotopic areas. Furthermore, when V2 and V3 were split into ventral and dorsal sub-ROIs, ventral retinotopic areas V2v and V3v preferentially differentiated between the two conditions whereas the corresponding dorsal areas V2d and V3d did not. In contrast, within hMT+, %BOLD signal was significantly greater in the no-Grouping condition. Conclusion: Nonlocal processing within, between, or to ventral retinotopic cortex at least as early as V2v, and including V3v, and V4v, underlies perceptual grouping via temporal synchrony. Hum Brain Mapp, 2008. © 2007 Wiley-Liss, Inc. [source] Electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia arising from superior tricuspid annulusINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 7 2008J. X. Yin Summary Objectives:, This study describes the electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia (AT) arising from superior tricuspid annulus in six (1.9%) patients of a consecutive series of 320 patients. Methods:, Six patients (mean age 42 ± 22 years) with a mean cycle length of 326 ms of a consecutive series of 320 patients undergoing radiofrequency ablation for focal AT were mapped. Results:, During electrophysiologic study, tachycardia could be induced in five patients with programmed atrial extrastimuli while a spontaneous onset and offset with ,warm-up and cool-down' phenomenon was seen in the other patient. During tachycardia, P-wave morphology in Lead I, II, III and aVF was upright in all the six patients. The precordial leads were dominantly negative or isoelectric in V1,V2 and positive in V5,V6 with a transition at V3 or V4. Moreover, the tachycardia was sensitive to intravenous administration of adenosine triphosphate in five of six patients. Conclusions:, Radiofrequency ablation was performed successfully in all patients (mean 4.5 ± 1.2 applications). No recurrence of AT was observed after a mean follow-up of 8 ± 6 months. Thus, AT arising from superior tricuspid annulus is rare. Radiofrequency ablation of this kind of AT is safe and effective. [source] Kinetics and mechanism of esterification of epoxy resin with methacrylic acid in the presence of tertiary aminesADVANCES IN POLYMER TECHNOLOGY, Issue 1 2005Akanksha Srivastava Abstract The synthesis of vinyl ester resins V1, V2, and V3 was carried out using bisphenol-A based epoxy resin and methacrylic acid in the presence of triethyl-, tripropyl-, and tributyl-amines, respectively. The reaction follows first-order kinetics. The interaction between acid and amine was investigated by IR spectroscopy which shows absorptions corresponding to the formation of activated acid,catalyst complex. The specific rate constants, calculated by regression analysis, were found to obey an Arrhenius expression. The kinetic and thermodynamic parameters: activation energy, frequency factor, entropy, enthalpy, and free energy revealed that the reaction was spontaneous and irreversible with a highly ordered activated complex. The activation energy of the esterification of epoxy resin in the presence of tertiary amines increases in order V1 < V2 < V3. The experimental results were explained by proposing a reaction mechanism and deriving the rate equation. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24:1,13, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20026 [source] Discovery and design of novel inhibitors of botulinus neurotoxin A: targeted ,hinge' peptide librariesJOURNAL OF APPLIED TOXICOLOGY, Issue 1 2003J. Hayden Abstract Intoxication by the zinc protease botulinus neurotoxin A (BoNT-A) results from cleavage of a single Q,R bond in the neuronal protein SNAP-25, which disables the docking mechanism required for neurotransmitter release. In the present study, potential inhibitors of BoNT-A were assessed from their effects on the BoNT-A cleavage of a synthetic 17-mer peptide (SNAP-25, residues 187,203) spanning the Q,R cleavage site. Compounds that inhibited BoNT-A included thiols (zinc chelators) such as dithiothreitol, dimercaptopropanesulfonic acid, mercaptosuccinic acid and captopril. In addition, compounds containing multiple acidic functions, such as the SNARE motif V2 (ELDDRADALQ), the tripeptide Glu-Glu-Glu and the steroid glycoside glycyrrhizic acid, were effective inhibitors. ,Hinge' peptide mini-libraries (PMLs) having the structure acetyl-X1 -X2 -linker-X3 -X4 -NH2 or X1 -X2 -linker-X3, where X1,X4 were mixtures of selected amino acids and the flexible linker was 4-aminobutyric acid, also provided effective inhibition. Targeted PMLs containing the acidic amino acids Asp and Glu, the scissile-bond amino acids Gln and Arg and the zinc chelators His and Cys produced pronounced inhibition of BoNT-A. Deconvolution of these libraries will provide novel ligands with improved inhibitory potency as leads in the design of peptide mimetics to treat BoNT poisoning. Copyright ? 2003 Crown in the right of Canada. Published by John Wiley and Sons, Ltd. [source] Focal Atrial Tachycardia Originating from the Left Atrial Appendage: Electrocardiographic and Electrophysiologic Characterization and Long-Term Outcomes of Radiofrequency AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2007WANG YUN-LONG M.D. Introduction: This study sought to investigate electrophysiologic characteristics and radiofrequency ablation (RFA) in patients with focal atrial tachycardia (AT) arising from the left atrial appendage (LAA). Methods: This study included seven patients undergoing RFA with focal AT. Activation mapping was performed during tachycardia to identify an earlier activation in the left atria and the LAA. The atrial appendage angiography was performed to identify the origin in the LAA before and after RFA. Results: AT occurred spontaneously or was induced by isoproterenol infusion rather than programmed extrastimulation and burst atrial pacing in any patient. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P wave was highly positive in inferior leads in all patients. Lead V1 showed upright or biphasic (±) component in all patients. Lead V2,V6 showed an isoelectric component in five patients or an upright component with low amplitude (<0.1 mV) in two patients. Earliest endocardial activity occurred at the distal coronary sinus (CS) ahead of P wave in all seven patients. Mean tachycardia cycle length was 381 ± 34 msec and the earliest endocardial activation at the successful RFA site occurred 42.3 ± 9.6 msec before the onset of P wave. RFA was acutely successful in all seven patients. Long-term success was achieved in seven of the seven over a mean follow-up of 24 ± 5 months. Conclusions: The LAA is an uncommon site of origin for focal AT (3%). There were consistent P-wave morphology and endocardial activation associated with this type of AT. The LAA focal ablation is safe and effective. Long-term success was achieved with focal ablation in all patients. [source] Electrocardiographic and Electrophysiologic Characteristics of Midseptal Accessory PathwaysJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2005SHIH-LING CHANG M.D. Background: The purpose of the present study was to investigate the electrocardiographic and electrophysiologic characteristics of right midseptal (RMS) and left midseptal (LMS) accessory pathways (APs), and to develop a stepwise algorithm to differentiate RMS from LMS APs. Methods and Results: From May 1989 to February 2004, 1591 patients with AP-mediated tachyarrhythmia underwent RF catheter ablation in this institution, and 38 (2.4%) patients had MS APs. The delta wave and precordial QRS transition during sinus rhythm, retrograde P wave during orthodromic tachycardia, and electrophysiologic characteristic and catheter ablation in 30 patients with RMS APs and 8 patients with LMS APs were analyzed. There was no significant difference in electrophysiologic characteristics and catheter ablation between RMS and LMS APs. The polarity of retrograde P wave during orthodromic tachycardia also showed no statistical difference between patients with RMS and LMS APs. The delta wave polarity was positive in leads I, aVL, and V3 to V6 in patients with RMS and LMS APs. Patients with LMS APs had a higher incidence of biphasic delta wave in lead V1 than patients with RMS APs (80% vs. 15%, P = 0.012). The distributions of precordial QRS transition were different between RMS APs (leads V2; n = 10, V3; n = 7 and V4; n = 3) and LMS APs (leads V1; n = 1 and V2; n = 4) (P = 0.03). The combination of a delta negative wave in lead V1 or precordial QRS transition in lead V3 or V4 had a sensitivity of 90%, specificity of 80%, positive predictive value of 95%, and negative predictive value of 66% in predicting an RMS AP. Conclusions: Delta wave polarity in lead V1 and precordial QRS transition may differentiate RMS and LMS APs. [source] Radiofrequency Catheter Ablation of Postinfarction Ventricular Tachycardia from the Proximal Coronary SinusJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2001JOSEF KAUTZNER M.D., Ph.D. VT Ablation from the Coronary Sinus. Optimum strategy for radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) after inferior wall myocardial infarction (MI) that originates from the posteroseptal process of the left ventricle is not known. We describe a case report of a 57,year-old man who developed recurrent post-MI VT with ECG morphology consistent with this type of VT (i.e., left bundle branch block pattern with predominant R waves from V2 to V6 and left-axis deviation). Endocardial mapping and entrainment during VT demonstrated a critical isthmus of the reentrant circuit in the proximal coronary sinus. RF application terminated VT and rendered it noninducible. [source] Relatively Benign Clinical Course in Asymptomatic Patients with Brugada-Type Electrocardiogram Without Family History of Sudden DeathJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2001SHIHO TAKENAKA M.D. Asymptomatic Brugada-Type ECG.Introduction: The incidence of sudden death or ventricular fibrillation (VF) in asymptomatic Brugada syndrome patients with a family history of sudden death is reported to be very high. However, there are few reports on the prognosis of asymptomatic Brugada syndrome patients without a family history of sudden death. Methods and Results: Eleven patients (all male; mean age 40.5 ± 9.6 years, range 26 to 56) with asymptomatic Brugada-type ECG who had no family history of sudden death were evaluated. The degrees of ST segment elevation and conduction delay on signal-averaged ECG (SAECG) before and after pilsicainide were evaluated in all 11 patients. VF inducibility by ventricular electrical stimulation also was evaluated in 8 of 11 patients. Patients were followed for a period of 9 to 84 months (mean 42.5 ± 21.6). The J point level was increased (V1 :0.19 ± 0.09 mV to 0.36 ± 0.23 mV; V2: 0.31 ± 0.12 mV to 0.67 ± 0.35 mV) by pilsicainide. Conduction delay was increased (total QRS: 112.2 ± 6.3 msec to 131 7 ± 6.3 msec; under 40 , V: 42.0 ± 8.5 msec to 52.7 ± 12.7 msec; last 40 msec: 17.4 ± 5.9 , V to 10.4 ± 6.1 , V) on SAECG by pilsicainide. VF was induced in only 1 of 8 patients. None of the patients had syncope or sudden death during a mean follow-up of 42.5 ± 21.6 months. Conclusion: This study suggests that asymptomatic patients with Brugada-type ECG who have no family history of sudden death have a relatively benign clinical course. [source] domain averaged Fermi holes;JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2003chemical bond; The recently proposed approach based on the analysis of domain-averaged Fermi holes was applied to the study of the nature of metalmetal bonding in transition metal complexes and clusters. The main emphasis was put on the scrutiny of the systems assumed to contain direct multiple metalmetal bonds. The studied systems involve: (1) systems of the type M2X6 (M = Mo, W, X = CH3) anticipated to contain metalmetal triple bonds; (2) the molecule of W2Cl8(4,) as the representative of the systems with quadruple metalmetal bonding; (3) diatomic molecules Mo2 and V2 considered as the potential candidates for higher than quadruple metalmetal bonding. Although the resulting picture of bonding has been usually shown to agree with the original expectations based on early simple MO models, some examples were also found in which the conclusions of the reported analysis display dramatic sensitivity to the quality of the wave function used for the generation of the Fermi holes. In addition to this we also report some examples where the original theoretical predictions of multiplicity of metalmetal bonds have to be corrected. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1829,1838, 2003 [source] Balanced judicious bipartitions of graphsJOURNAL OF GRAPH THEORY, Issue 3 2010Baogang Xu Abstract A bipartition of the vertex set of a graph is called balanced if the sizes of the sets in the bipartition differ by at most one. B. Bollobás and A. D. Scott, Random Struct Alg 21 (2002), 414,430 conjectured that if G is a graph with minimum degree of at least 2 then V(G) admits a balanced bipartition V1, V2 such that for each i, G has at most |E(G)|/3 edges with both ends in Vi. The minimum degree condition is necessary, and a result of B. Bollobás and A. D. Scott, J. Graph Theory 46 (2004), 131,143 shows that this conjecture holds for regular graphs G(i.e., when ,(G)=,(G)). We prove this conjecture for graphs G with ; hence, it holds for graphs ]ensuremathG with . © 2009 Wiley Periodicals, Inc. J Graph Theory 63: 210,225, 2010 [source] Improved bounds for the chromatic number of a graphJOURNAL OF GRAPH THEORY, Issue 3 2004S. Louis Hakimi Abstract After giving a new proof of a well-known theorem of Dirac on critical graphs, we discuss the elegant upper bounds of Matula and Szekeres-Wilf which follow from it. In order to improve these bounds, we consider the following fundamental coloring problem: given an edge-cut (V1, V2) in a graph G, together with colorings of ,V1, and ,V2,, what is the least number of colors in a coloring of G which "respects" the colorings of ,V1, and ,V2, ? We give a constructive optimal solution of this problem, and use it to derive a new upper bound for the chromatic number of a graph. As easy corollaries, we obtain several interesting bounds which also appear to be new, as well as classical bounds of Dirac and Ore, and the above mentioned bounds of Matula and Szekeres-Wilf. We conclude by considering two algorithms suggested by our results. © 2004 Wiley Periodicals, Inc. J Graph Theory 47: 217,225, 2004 [source] Expression of the Genes Encoding the Vasopressin-Activated Calcium-Mobilizing Receptor and the Dual Angiotensin II/Vasopressin Receptor in the Rat Central Nervous SystemJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2000Hurbin The distributions of two newly discovered receptors, the vasopressin-activated calcium-mobilizing receptor (VACM-1) and the dual angiotensin II/vasopressin receptor (AII/AVP), in the central nervous system (CNS) of the rat were determined using reverse transcriptase-polymerase chain reaction and in situ hybridization. The sequence of the rat VACM-1 cDNA was determined and found very homologous to the rabbit and human sequences. Both VACM-1 and AII/AVP receptor genes were widely expressed in the brain, but differed according to the cell type studied. Glial cells were very faintly labelled. The epithelial cells of the choroid plexuses, the ependymal cells and the pia mater were all labelled. Both genes were most active in neurones throughout the CNS. VACM-1 and AII/AVP receptors were detected in neurones previously shown to possess V1a and V1b vasopressin receptors, and/or the AT1 and AT2 angiotensin II receptors in many brain areas. This was the case for the magnocellular neurones of the supraoptic and paraventricular nuclei of the hypothalamus. We suggest that the VACM-1 and AII/AVP receptors may account for the V2 -like responses to vasopressin by these neurones which lack a genuine V2 vasopressin receptor. [source] The characterization of versican and its message in human articular cartilage and intervertebral discJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2002Robert Sztrolovics Splicing variation of the versican message and size heterogeneity of the versican core protein were analyzed in human articular cartilage and intervertebral disc. Splicing variation of the message was studied by PCR analysis to detect the presence or absence of exons 7 and 8, which encode large chondroitin sulfate attachment regions. At all ages in normal cartilage from the third trimester fetus to the mature adult, the presence of the versican isoform possessing exon 8 but not exon 7 (V1) could be readily detected. The message isoforms possessing neither exon 7 nor 8 (V3) or both exons 7 and 8 (V0) were only detectable in the fetus, and the isoform possessing only exon 7 (V2) was never detected. In osteoarthritic cartilage and in adult intervertebral disc the versican message pattern was the same as that observed in the normal adult with only the isoform possessing exon 8 being detected. Core protein heterogeneity was studied by immunoblotting following enzymic removal of the glycosaminoglycan chains from the proteoglycan, using an antibody recognizing the globular G1 region of versican. All articular cartilage extracts from the fetus to the mature adult contained multiple core protein sizes of greater than 200 kDa. The adult cartilage extracts tended to have an increased proportion of the smaller sized core proteins and osteoarthritic cartilage possessed similar core protein sizes to the normal adult. In contrast, intervertebral disc at all post-natal ages showed a greater range of size heterogeneity with a prominent component of about 50 kDa. The abundance of this component increased if the samples were treated with keratanase prior to analysis, suggesting that the G1 region of versican in disc can be substituted with keratan sulfate. The increased presence of versican in the disc relative to articular cartilage may suggest a more pronounced functional role for this proteoglycan, particularly in the nucleus pulposus. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Comparison of the Bayer VERSANT HCV RNA 3.0 and the Roche COBAS Amplicor HCV Monitor, Version 2.0, assays in HCV genotype 4 infectionJOURNAL OF VIRAL HEPATITIS, Issue 11 2007W. Jessner summary Prediction of treatment response is clinically important in chronic hepatitis C virus (HCV) genotype 4 infection. Early viral kinetics is useful in this respect for genotype 1 but interpretation is dependent on assay linearity and reproducibility. The VERSANT HCV RNA 3.0 (bDNA-3.0) and the COBAS Amplicor HCV Monitor 2.0 (HCM-2.0) have been widely used quantitative assays. We wanted to comparatively evaluate the two tests in a large genotype 4 sample. Genotyping was performed by NS5b sequencing. Viral load was tested in parallel in 32 patients at least six times on antiviral therapy with interferon , (IFN,). Totally, 198 samples within a quantitative range from undetectable to about 7 × 106 IU/mL (bDNA-3.0) were obtained and compared. Twenty-two samples with viral load above 500 000 IU/mL tested by HCM-2.0 were 1:100 diluted and retested. Quantitative values were fitted to a third order polynomial (M = 0.118303 + 1.07503 × V+ 0.0112128 × V2 , 0.0055504 × V3; M,HCM-2.0, V,bDNA-3.0, both log IU/mL) showing progressive nonlinearity of HCM-2.0 above 100 000 IU/mL but better clinical sensitivity with respect to bDNA-3.0. Dilution lead to a gain of at least a factor of 2.7 and thus, overestimation compared with bDNA-3.0. Deviation from linearity and overestimation upon dilution by HCM-2.0 are similar with HCV genotype 4, compared with other HCV genotypes. Differences in test performance were not detected for subtypes but for individual patients possibly related to specific quasispecies patterns. The interpretation of viral kinetic data becomes difficult due to overestimation upon dilution of baseline values by HCM-2.0. [source] Connectedness of digraphs and graphs under constraints on the conditional diameterNETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2005X. Marcote Abstract Given a digraph G with minimum degree , and an integer 0, , , ,, consider every pair of vertex subsets V1 and V2 such that both the minimum out-degree of the induced subdigraph G[V1] and the minimum in-degree of G[V2] are at least ,. The conditional diameter D, of G is defined as the maximum of the distances d(V1, V2) between any two such vertex subsets. Clearly, D0 is the standard diameter and D0 , D1 , ··· , D, holds. In this article, we guarantee appropriate lower bounds for the connectivities and superconnectivities of a digraph G when D, , h(,,), h(,,) being a function of the parameter ,,,which is related to the shortest paths in G. As a corollary of these results, we give some constraints of the kind D, , h(,,), which assure that the digraph is maximally connected, maximally edge-connected, superconnected, or edge-superconnected, extending other previous results of the same kind. Similar statements can be obtained for a graph as a direct consequence of those for its associated symmetric digraph. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 45(2), 80,87 2005 [source] Superconnected digraphs and graphs with small conditional diametersNETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2002C. Balbuena Abstract The conditional diameter D, of a digraph G measures how far apart a pair of vertex sets V1 and V2 can be in such a way that the minimum out-degree and the minimum in-degree of the subdigraphs induced by V1 and V2, respectively, are at least ,. Thus, D0 is the standard diameter and D0 , D1 , ··· , D,, where , is the minimum degree. We prove that if D, , 2l , 3, where l is a parameter related to the shortest paths, then G is maximally connected, is superconnected, or has a good superconnectivity, depending only on whether , is equal to ,,/2,, ,(, , 1)/2,, or ,(, , 1)/3,, respectively. In the edge case, it is enough that D, , 2l , 2. The results for graphs are obtained as a corollary of those for digraphs, because, in the undirected case, l = ,(g , 1)/2,, g being the girth. © 2002 Wiley Periodicals, Inc. [source] Electrocardiogram-Based Algorithm to Predict the Left Ventricular Lead Position in Recipients of Cardiac Resynchronization SystemsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009SYLVAIN PLOUX M.D. Introduction: Biventricular pacing is associated with various electrocardiographic patterns depending on the position of the left ventricular (LV) lead. We aimed to develop an electrocardiogram-based algorithm to predict the position of the LV lead. Methods: The algorithm was developed in 100 consecutive recipients of cardiac resynchronization therapy (CRT) systems. QRS axis, morphology, and polarity were analyzed with a view to define the specific electrocardiographic characteristics associated with the various LV lead positions. The algorithm was prospectively validated in 50 consecutive CRT device recipients. Results: The first analysis of the algorithm was the QRS morphology in V1. A positive R wave in V1 suggested LV lateral or posterior wall stimulation. A QS pattern was specific of anterior LV leads. In the presence of an R wave in V1, V6 was analyzed to distinguish between an inferior and anterior LV lead. Inferior leads were never associated with a positive V6. To differentiate between lateral and posterior positions, we analyzed the pattern in V2. Lateral leads were associated with an R morphology in V1 and a negative V2. Posterior leads were associated with an R morphology in V1 and V2. The algorithm allowed a reliable distinction between an inferior or anterior and a lateral or posterior lead position in 90% of patients. Inferior, anterior, lateral, and posterior positions were reliably distinguished in 80% of patients. Conclusion: This algorithm predicted the position of the LV lead with a high sensitivity and predictive value. [source] Exercise-Attenuation of Q-Waves in II, III, and aVF, and R-Waves in V1 and V2 in a Patient with an Inferior Infarction and Anterior Wall IschemiaPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2008JOHN E. MADIAS M.D. A 63-year-old male patient with inferior infarction revealed transient attenuation of the Q-waves in II, III, and aVF, and R-waves in V1,V3 during an exercise stress test. Myocardial scintigraphy disclosed ischemia of the anterior wall and coronary arteriography, a 90% stenosis of the left main coronary artery (LMCA). The mechanism involved appears to be a transient failure of the anterior wall to generate adequate depolarization forces for the genesis of Q-waves in the inferior leads and R-waves in the anterior leads. This electrocardiogram sign is diagnostic of severe anterior wall ischemia due to left anterior descending or LMCA stenosis. [source] Sudden Cardiac Death with Left Main Coronary Artery Occlusion in a Patient Whose Presenting ECG Suggested Brugada SyndromePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2003TADAYOSHI HATA This article describes a patient who died suddenly during Holter ECG monitoring. A ventricular premature systole with an extremely short coupling interval of 240 ms was immediately followed by torsades de pointes, soon degenerating into ventricular fibrillation. Retrospective survey of the patient's medical records revealed an incomplete right bundle branch block (iRBBB) configuration with fluctuating saddle back-type ST elevation in leads V1 and V2, these suggesting Brugada syndrome. Autopsy showed complete thrombotic occlusion of the left main coronary artery. (PACE 2003; 26:2175,2177) [source] Intravenous Administration of Class I Antiarrhythmic Drug Induced T Wave Alternans in an Asymptomatic Brugada Syndrome PatientPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2003KIMIE OHKUBO A 53-year-old man with an abnormal ECG was referred to the Nihon University School of Medicine. The 12-lead ECG showed right bundle branch block and saddleback-type ST elevation in leads V1,V3 (Brugada-type ECG). Signal-averaged ECG showed positive late potentials. Double ventricular extrastimuli (S1: 500 ms, S2: 250 ms, S3: 210 ms) induced VF. Amiodarone (200 mg/day) was administered for 6 months and programmed ventricular stimulation was repeated. VF was induced again by double ventricular stimuli (S1: 600 ms, S2: 240 ms, S3: 170 ms). Intravenous administration of class Ic antiarrhythmic drug, pilsicainide (1 mg/kg), augmented ST-T elevation in leads V1,V3, and visible ST-T alternans that was enhanced by atrial pacing was observed in leads V2 and V3. Visible ST-T wave alternans disappeared in 15 minutes. However, microvolt T wave alternans was present during atrial pacing at a rate of 70/min without visible ST-T alternans. (PACE 2003; 26:1900,1903) [source] ST Segment and T Wave Alternans in a Patient with Brugada SyndromePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2000HIROSHI TADA We describe a patient with Brugada syndrome in whom J point and ST-segment elevation in leads V1 and V2 were augmented by atrial pacing and intravenous administration of propranolol or cibenzoline. Significant T wave alternans with a 2:1 appearance of terminal negative T wave was observed in the absence and presence of atrial pacing after the administration of cibenzoline. The cellular mechanism responsible for T wave alternans. beat-to-beat appearance of terminal negative T wave and augmented J point and ST-segment elevation is discussed [source] Clonidine disposition in children: a population analysisPEDIATRIC ANESTHESIA, Issue 6 2007AL Potts Background:, There are few data describing clonidine population pharmacokinetics in children (0,15 years) despite common use. Current paediatric data, described in terms of elimination half-life or Cmax and Tmax, poorly explain variability in drug responses among individuals representative of those in whom the drug will be used clinically. Methods:, Published data from four studies investigating clonidine PK after intravenous, rectal and epidural administration (n = 42) were combined with an open-label study undertaken to examine the pharmacokinetics of IV clonidine 1,2 ,g·kg,1 bolus in children after cardiac surgery (n = 30, EC approval granted). A population pharmacokinetic analysis of clonidine time-concentration profiles (380 observations) was undertaken using nonlinear mixed effects modelling. Estimates were standardised to a 70 kg adult using allometric size models. Results:, Children had a mean age of four (SD 3.6 years, range 1 week,14 years) year and weight 17.8 (SD 12.6, range 2.8,60 kg). A two compartment disposition model with first order elimination was superior to a one compartment model. Population parameter estimates (between subject variability) were clearance (CL) 14 (CV 28.3%) 1 h,1·70 kg,1, central volume of distribution (V1) 56.7 (67.5%) l·70 kg,1, inter-compartment clearance (Q) 143 (19.1%) l h,1 70 kg,1 and peripheral volume of distribution (V2) 123 (72.8%) l.70kg,1. Clearance at birth was 4.7 l·h,1·70kg,1 and matured with a half-time of 25.5 weeks to reach 85% adult rate by 1 year of age. The volumes of distribution, but not clearance, were increased after cardiac surgery (V1 180%, V2 117%). There was a lag time of 2.6 (CV 64%) min before absorption began in the rectum. The absorption half-life from the epidural space was slower than that from the rectum 1.04 (CV31%) h vs 0.28 (CV24%) h. The relative bioavailability of epidural and rectal clonidine was unity (F = 1). Conclusions:, Clearance in neonates is approximately one third that described in adults, consistent with immature clearance pathways. Maintenance dosing, which is a function of clearance, should be reduced in neonates and infants when using a target concentration approach. [source] 6th International Workshop on Expert Evaluation & Control of Compound Semiconductor Materials & TechnologiesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003Bálint P The EXMATEC workshops are a series of biannial conferences with the aim to bring together research and development specialists involved in compound semiconductor material physics, chemistry, process technology, characterization and device fabrication. EXMATEC 2002 is the continuation of successful meetings, previously held in Lyon, Parma, Freiburg, Cardiff and Heraklion. The central topics were development, improvement and application of new and advanced methods in the fabrication and evaluation of compound semiconductor materials and structures to develop understanding of the interrelationship between structural, electrical and other material properties and device characteristics, such as performance, reliability, reproducibility, lifetime, yield, etc. The conference topics apply to all compound semiconductor materials (III,V, II,VI, IV,IV, II,IV,V2), related structures and processing steps (from substrate and epitaxial growth to complete devices) and cover instrumentation and characterization issues. The full Proceedings of EXMATEC 2002 are published in the second issue of the new journal series physica status solidi , conferences Vol. 0, No. 2 (2003). As one representative example of the topics presented at this conference, the cover picture of the present issue issue of phys. stat. sol. (a) shows the band scheme of a typical GaInAs/AlInAs superlattice quantum cascade laser, taken from the invited paper by Razeghi and Slivken [1]. [source] Receptive-field properties of V1 and V2 neurons in mice and macaque monkeysTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 11 2010Gert Van den Bergh Abstract We report the results of extracellular single-unit recording experiments where we quantitatively analyzed the receptive-field (RF) properties of neurons in V1 and an adjacent extrastriate visual area (V2L) of anesthetized mice with emphasis on the RF center-surround organization. We compared the results with the RF center-surround organization of V1 and V2 neurons in macaque monkeys. If species differences in spatial scale are taken into consideration, mouse V1 and V2L neurons had remarkably fine stimulus selectivity, and the majority of response properties in V2L were not different from those in V1. The RF center-surround organization of mouse V1 neurons was qualitatively similar to that for macaque monkeys (i.e., the RF center is surrounded by extended suppressive regions). However, unlike in monkey V2, a significant proportion of cortical neurons, largely complex cells in V2L, did not exhibit quantifiable RF surround suppression. Simple cells had smaller RF centers than complex cells, and the prevalence and strength of surround suppression were greater in simple cells than in complex cells. These findings, particularly on the RF center-surround organization of visual cortical neurons, give new insights into the principles governing cortical circuits in the mouse visual cortex and should provide further impetus for the use of mice in studies on the genetic and molecular basis of RF development and synaptic plasticity. J. Comp. Neurol. 518:2051,2070, 2010. © 2010 Wiley-Liss, Inc. [source] Postnatal phenotype and localization of spinal cord V1 derived interneuronsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2005Francisco J. Alvarez Abstract Developmental studies identified four classes (V0, V1, V2, V3) of embryonic interneurons in the ventral spinal cord. Very little is known, however, about their adult phenotypes. Therefore, we characterized the location, neurotransmitter phenotype, calcium-buffering protein expression, and axon distributions of V1-derived neurons in the adult mouse spinal cord. In the mature (P20 and older) spinal cord, most V1-derived neurons are located in lateral LVII and in LIX, few in medial LVII, and none in LVIII. Approximately 40% express calbindin and/or parvalbumin, while few express calretinin. Of seven groups of ventral interneurons identified according to calcium-buffering protein expression, two groups (1 and 4) correspond with V1-derived neurons. Group 1 are Renshaw cells and intensely express calbindin and coexpress parvalbumin and calretinin. They represent 9% of the V1 population. Group 4 express only parvalbumin and represent 27% of V1-derived neurons. V1-derived Group 4 neurons receive contacts from primary sensory afferents and are therefore proprioceptive interneurons. The most ventral neurons in this group receive convergent calbindin-IR Renshaw cell inputs. This subgroup resembles Ia inhibitory interneurons (IaINs) and represents 13% of V1-derived neurons. Adult V1-interneuron axons target LIX and LVII and some enter the deep dorsal horn. V1 axons do not cross the midline. V1-derived axonal varicosities were mostly (>80%) glycinergic and a third were GABAergic. None were glutamatergic or cholinergic. In summary, V1 interneurons develop into ipsilaterally projecting, inhibitory interneurons that include Renshaw cells, Ia inhibitory interneurons, and other unidentified proprioceptive interneurons. J. Comp. Neurol. 493:177,192, 2005. © 2005 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||