bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuclear Magnetic Resonance: Basic Principles and Liquid State Spectroscopy
Authors: Utz Marcel 
Published: November 2003

AbstractThe basic physical principles behind nuclear magnetic resonance spectroscopy are introduced in this chapter, along with spectroscopic techniques for the study of liquids. The phenomenon of magnetic resonance is described from a quantum mechanical point of view, using the density operator formalism that has become the standard in the field. Interactions of the nuclear spin with the molecular surroundings such as the chemical shift of the resonance frequency and the scalar spin–spin coupling are introduced. The effect of radio‐frequency pulses on the nuclear spin state is discussed, as well as the spin– lattice and spin–spin relaxation processes that take the spin system back to its thermal equilibrium state in the absence of external perturbations. The principle of multidimensional spectroscopy is described, and specific liquid‐state NMR techniques that have applications in materials science are discussed.
Ca2+/calmodulin‐mediated neurotransmitter release and neurobehavioural deficits following lead exposure
Authors: Gill K. D. , Gupta Vandana , Sandhir Rajat 
Published: November 2003

AbstractThe present study was designed to investigate the effect of in vitro and in vivo lead exposure on calmodulin‐mediated neurotransmitter release from synaptic vesicles with a view to explain the mechanism involved in its behavioural effects. It was observed that lead stimulated calmodulin, in terms of its ability to activate cAMP phosphodiesterase, following in vitro and in vivo exposure. Lead was also seen to enhance calmodulin‐mediated synaptic vesicle protein phosphorylation. The increase in lead‐induced synaptic vesicle protein phosphorylation was accompanied by enhanced release of acetylcholine from synaptic vesicles following in vitro lead exposure by a calmodulin‐dependent mechanism. The ability of Ca2+/calmodulin to evoke acetylcholine release was reduced in the synaptic vesicles isolated from lead‐exposed animals. Concomitantly, the levels of acetylcholine were found to decrease by 37.8% in the lead‐treated animals as compared to the controls. The neurochemical alterations following lead exposure were accompanied by neurobehavioural deficits in terms of impaired motor and cognitive functions. The results from the present study clearly suggest that lead exerts its neurotoxic effects by interfering with Ca2+/calmodulin‐mediated neurotransmitter release that is eventually responsible for behavioural impairment. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of dietary vitamin E and selenium on arginase activity in the liver, kidneys, and heart of rats treated with high doses of glucocorticoid
Authors: Erişir Mine , Beytut Ebru , Ozan Sema , Aksakal Mesut 
Published: November 2003

AbstractThe effects of dietary intake of vitamin E and selenium on arginase activity in the liver, kidneys, and heart of rats treated with high doses of prednisolone were investigated. Rats were divided into five groups. Groups 3, 4, and 5 received a daily supplement in their drinking water of vitamin E, Se, and a combination of vitamin E and Se, respectively, for 30 days. For 3 days subsequently, the control group (group 1) was given a placebo, and the remaining four groups were injected intramuscularly with prednisolone. The tissue samples were collected from each group at 4, 8, 12, 24, and 48 h after the last administration of prednisolone. In the group treated with prednisolone alone, arginase activity in the liver was found to have increased at all the time periods, whereas it had decreased significantly in the heart at 48 h. Arginase activity in the kidneys was not affected by prednisolone. Compared to the control and prednisolone groups, arginase activity in the kidneys and heart of the vitamin E‐ and Se‐supplemented groups was found to be significantly increased at all time periods, however, no difference was seen in the combination group. Arginase activity in the liver of the vitamin E‐supplemented group was found to have decreased at all time periods, however, in the Se group compared to the prednisolone group it had reduced at 24 and 48 h only. In the combination group compared to the prednisolone group, liver arginase activity increased constantly up to 12 h returning to normal values at 48 h. Vitamin E and Se in combination may prevent the changes in arginase activity in various tissues caused by prednisolone. Copyright © 2003 John Wiley & Sons, Ltd.
The protective mechanisms of defibrotide on liver ischaemia–reperfusion injury
Authors: Aydemir E. O. , Var A. , Uyanik B. S. , Ilkgül Ö. , Aydede H. , Sakarya A. 
Published: November 2003

AbstractDuring some surgical interventions, temporary occlusion of the hepatic blood supply may cause ischaemia–reperfusion (I/R) injury and hepatic dysfunction. In this study the protective effect of defibrotide (DEF) was evaluated in a rat model of liver I/R injury. Four groups of rats were subjected to the following protocols: saline infusion without ischaemia, DEF infusion without ischaemia, DEF infusion with hepatic I/R, and saline infusion with hepatic I/R. After a midline laporatomy, liver ischaemia was induced by 45 min of portal occlusion. DEF 175 mg/kg−1 was infused before ischaemia in 10 ml of saline. The same volume of saline was infused into the control animals. At the end of the 45‐min reperfusion interval, the animals were sacrified. Superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) enzyme activities were determined in haemolysates, and malondialdehyde (MDA) level in the liver tissue was measured. Tissue MDA levels were significantly higher in the I/R plus saline group compared to the sham operation control groups (p < 0.01 and p < 0.05, respectively). Tissue MDA levels decreased in the DEF plus I/R group compared to the I/R plus saline group (p < 0.05), but DEF could not reduce tissue lipid peroxidation to the levels of the control sham operation groups. SOD and GSH‐Px enzyme activities were significantly higher in DEF‐treated animals than in the other groups (p < 0.05). These results suggest that DEF protects liver against I/R injury by increasing the antioxidant enzyme levels. Copyright © 2003 John Wiley & Sons, Ltd.
Age‐related changes of the endogenous cardiolipin and plasmalogens of guinea pig kidney and their in vitro hydrolysis by endogenous phospholipases: a thin layer chromatographic analysis in conjunction with densitometric measurement
Authors: Helmy Fatma M. , Hack Marvin H. , Juracka Amal 
Published: November 2003

AbstractThe phosphoglycerides profile of guinea pig kidney, fetal, young adult, and aged, and their in vitro response to the endogenous lipolytic enzymes, mainly in the phospholipase group were determined by TLC technology in conjunction with densitometric measurement. Changes in phosphoglycerides profile subsequent to in vitro incubation of these tissues at pH 7.4, and 38°C for 45 min and prior to phospholipid extraction has provided evidence relating to their respective lipolytic enzymes capabilities and age. These changes are mainly related to endogenous cardiolipin (CL), alkenyl phospholipids (phosphatidyl ethanolamine and phosphatidyl choline) and their endogenous deacylation to their respective lyso derivatives monolysocardiolipin (MLCL), lyso alkenyl phosphatidyl ethanolamine (LPE), and lyso alkenyl phosphatidyl choline (LPC) by endogenous phospholipases. The hydrolysis of the plasmalogen confirms the action of endogenous PLA2 on sn‐2 fatty acids of these compounds. Copyright © 2003 John Wiley & Sons, Ltd.
Production and characterization of α‐galactosidase from Aspergillus flavipes
Authors: Ozsoy Nurten , Berkkan Hakan 
Published: November 2003

AbstractAn extracellular α‐galactosidase from the culture filtrate of Aspergillus flavipes grown on melibiose as a carbon source was partially purified by hydroxylapatite and diethylaminoethylcellulose chromatographies. Electrophoretic analysis showed protein bands corresponding to α‐galactosidase and invertase activities. The optimum pH and temperature were determined as 4.5–5.0 and 45°C, respectively. The Km value for p‐nitrophenyl‐α‐d‐galactopyranoside was found to be 1.89 mm. The results reported in this study indicate that Aspergillus flavipes is indeed an active source of extracellular α‐galactosidase. Copyright © 2003 John Wiley & Sons, Ltd.
Carotid stenting in the bovine arch
Authors: Shaw James A. , Gravereaux Edwin C. , Eisenhauer Andrew C. 
Published: November 2003

AbstractWe report our experience in stent‐supported angioplasty of the left internal carotid artery in patients with anomalous origin of the left common carotid, the so‐called bovine arch, in which the right brachiocephalic and left carotid share a common trunk from the aortic arch. The occurrence of the anatomic variant is discussed, and techniques of femoral, brachial, and radial approaches are described. Catheter Cardiovasc Interv 2003;60:566–569. © 2003 Wiley‐Liss, Inc.
Blood flow velocity in donor coronary artery depends on the degree and pattern of collateral vessel development: A study using thrombolysis in myocardial infarction frame count method
Authors: Gatzov Plamen , Manginas Athanassios , Voudris Vassilis , Pavlides Gregory , Genchev Gencho D. , Cokkinos Dennis V. 
Published: November 2003

AbstractTo understand the influence of collateral vessels on the coronary flow, TIMI frame count (TFC) method was applied as a measure of mean coronary blood flow velocity in artery giving collateral blood supply to the other artery in angiograms of 76 patients with single occluded coronary artery: RCA giving collaterals to occluded LAD or LAD giving collaterals to occluded RCA. As a control group, TFC was applied in angiograms of 30 patients with mild or no coronary artery disease. TFC was lower (faster blood flow) in LAD giving collaterals to occluded RCA (43 patients) than in LAD in control group (21.8 ± 10.5 vs. 33.9 ± 20.8 frames; P < 0.01). Higher degree of collateral vessels (Rentrop classification) and mixed‐ and distal‐type collaterals (through the interventricular septum and heart apex) was associated with lower TFC. There was no difference in TFC in the RCA giving collaterals to an occluded LAD (33 patients) compared to the TFC in RCA in control group (16.6 ± 9.0 vs. 18.5 ± 6.0; P = NS), even in angiograms with higher degree of collateral vessel development. TFC was lower (faster blood flow) only in subgroups with mixed (proximal and distal types together in the same patient) and distal (through the interventricular septum and the apex of the heart) collateral types. A delayed contrast appearance in occluded LAD compared to occluded RCA has been found (35.1 ± 16.1 vs. 20.2 ± 7.3 frames; P < 0.001) with earlier contrast appearance in occluded LAD when proximal collateral vessels (through the conal and acute marginal branches of RCA) were presented. The coronary flow in donor arteries depends not only on the degree but also on the pattern of collateral vessels. The simple TFC method may facilitate the study of collateral filling pattern and offer insight into the influence of collaterals on the ventricular function. Catheter Cardiovasc Interv 2003;60:462–468. © 2003 Wiley‐Liss, Inc.
Hemodynamic complications of ventricular septal rupture after acute myocardial infarction
Authors: Sasseen Brett M. , Gigliotti Osvaldo S. , Lavine Steven , Gilmore Paul S. , Percy Robert , Bass Theodore A. 
Published: November 2003

AbstractVentricular septal rupture (VSR) is a rare but serious complication following acute myocardial infarction (MI). Patients may present with a new murmur associated with a thrill. Right heart catheterization will demonstrate elevated right atrial and pulmonary artery pressures as well as an oxygen step‐up at the right ventricular level. Patients with a right ventricular infarction or cardiogenic shock and a ventricular septal rupture have high in‐hospital mortality rates. Prompt diagnosis followed by surgical repair is essential for patients with VSR following MI. Catheter Cardiovasc Interv 2003;60:509–514. © 2003 Wiley‐Liss, Inc.
Distribution of mGluR1α and mGluR5 immunolabeling in primate prefrontal cortex
Authors: Muly E. Chris , Maddox Marcelia , Smith Yoland 
Published: November 2003

AbstractMetabotropic glutamate receptors (mGluRs) mediate important modulatory glutamatergic influences throughout the brain. However, the specific localization and functions of group I mGluR subtypes (mGluR1α and mGluR5) in cortical neurotransmission are not well known, particularly in primates. To address this issue, we used immunoelectron microscopy to compare the subcellular localizations of mGluR1α and mGluR5 in the prefrontal cortex of macaque monkeys. Both receptor subtypes were found in a variety of subcellular compartments, including spines, dendrites, preterminal axons, axon terminals, and glia; however, quantitative differences were found in the relative abundance of labeled elements for each receptor. The mGluR1α‐immunoreactive (‐IR) elements were overwhelmingly the spines and dendrites, with labeled terminals, axons, and glia seen more rarely. The mGluR5‐IR elements were also mostly spines and dendrites, but the proportion of labeled unmyelinated axons, terminals, and glia was higher than for mGluR1α‐IR elements. Double labeling with SMI‐32 and parvalbumin confirmed that both receptors were found in pyramidal cell and interneuron dendrites. The localization of mGluR1α to pyramidal cells in primate cortex contrasts with reports that mGluR1α is found almost exclusively in interneurons in rodent cortex. By using double labeling, we found no evidence for mGluR1α or mGluR5 in dopaminergic afferents to prefrontal cortex. The data presented here provide an anatomical substrate for a differential role of mGluR1α and mGluR5 in post‐and presynaptic actions of glutamate in primate prefrontal cortex. They further suggest differences in the cortical distribution of group I mGluRs between primates and rodents. J. Comp. Neurol. 467:521–535, 2003. © 2003 Wiley‐Liss, Inc.
The visual pulvinar in tree shrews I. Multiple subdivisions revealed through acetylcholinesterase and Cat‐301 chemoarchitecture
Authors: Lyon David C. , Jain Neeraj , Kaas Jon H. 
Published: November 2003

AbstractTree shrews are highly visual mammals closely related to primates. They have a large visual pulvinar complex, but its organization and relation to visual cortex is only partly known. We processed brain sections through the pulvinar with seven different procedures in an effort to reveal histologically distinct compartments. The results revealed three major subdivisions. A dorsal subdivision, Pd, stains darkly for acetylcholinesterase (AChE) and occupies the dorsoposterior one‐third of the pulvinar complex. A ventral subdivision, Pv, stains darkly when processed with the Cat‐301 antibody and occupies the ventroanterior fifth of the pulvinar complex along the brachium of the superior colliculus. Unexpectedly, part of Pv is ventral to the brachium. A large central subdivision, Pc, stains moderately dark for AChE and cytochrome oxidase (CO), and very light for Cat‐301. Pc includes about half of the pulvinar complex, with parts on both sides of the brachium of the superior colliculus. These architectonic results demonstrate that the pulvinar complex of tree shrews is larger and has more subdivisions than previously described. The complex resembles the pulvinar of primates by having a portion ventral to the brachium and by having histochemically distinct nuclei; the number of nuclei is less than in primates, however. J. Comp. Neurol. 467:593–606, 2003. © 2003 Wiley‐Liss, Inc.
Chaotic behaviours of stable second‐order digital filters with two's complement arithmetic
Authors: Ling Bingo Wing‐Kuen , Hung Wai‐Fung , Tam Peter Kwong‐Shun 
Published: November 2003

AbstractIn this paper, the behaviours of stable second‐order digital filters with two's complement arithmetic are investigated. It is found that even though the poles are inside the unit circle and the trajectory converges to a fixed point on the phase plane, that fixed point is not necessarily the origin. That fixed point is found and the set of initial conditions corresponding to such trajectories is determined. This set of initial conditions is a set of polygons inside the unit square, whereas it is an ellipse for the marginally stable case. Also, it is found that the occurrence of limit cycles and chaotic fractal pattern on the phase plane can be characterized by the periodic and aperiodic behaviours of the symbolic sequences, respectively. The fractal pattern is polygonal, whereas it is elliptical for the marginally stable case. Copyright © 2003 John Wiley & Sons, Ltd.
Application of duality principle to synthesis of single‐stage power‐factor‐correction voltage regulators
Authors: Tse C. K. , Lai Y. M. , Xie R. J. , Chow M. H. L. 
Published: November 2003

AbstractThe duality principle is applied to derive new single‐stage power‐factor‐correction (PFC) voltage regulators. This paper begins with an application of duality transformation to conventional discontinuous‐conduction‐mode buck, buck‐boost and boost converters. The resultingdual convertersoperate in the discontinuous capacitor voltage mode. These new converters provide the same PFC property, but in the dual manner. It is proved that in the practical case of the input being a voltage source, the mandatory insertion of inductance between the voltage input and the ‘dual PFC converter’ does not affect the power‐factor‐correcting property. A new single‐stage PFC regulator is derived by taking the dual of a well‐known circuit based on a cascade of conventional boost and buck converters. Analytical design expressions are derived, illustrating the relation between current stress and component values. Experiments are performed to confirm the operation of the circuit and its power‐factor‐correcting capability. Copyright © 2003 John Wiley & Sons, Ltd.
Nanostructure array of coupled RTDs as cellular neural networks
Authors: Karahaliloglu Koray , Balkir Sina 
Published: November 2003

AbstractThe processing capabilities of a proposed nanoelectronic device are investigated. The device is considered as a global dynamical system with local circuit model components. The system equations and the corresponding network model are presented. The characteristics of this network model are compared with the cellular neural networks. Certain characteristics of the network are analysed theoretically and demonstrated with circuit‐system level simulations. As a novel property, it is shown that the single layer nanodevice network structure is a basic reaction–diffusion system and it is capable of autowave propagation. Furthermore, the same network structure exhibits several image processing capabilities like image smoothing, edge enhancement, and horizontal or vertical line detection using simple arrangements of the device parameters. Copyright ©2003 John Wiley & Sons, Ltd.
A wavelet approach to fast approximation of steady‐state waveforms of power electronics circuits
Authors: Liu Ming , Tse Chi K. , Wu Jie 
Published: November 2003

AbstractWaveforms arising from power electronics circuits often contain slowly changing segments with high‐frequency details concentrated near the switching instants. Such a feature is consistent with the localization property of wavelets which are known in the signal processing literature to be highly suitable for describing fast changing edges embedded in slowly varying backgrounds. This paper considers the application of wavelet approximation to the steady‐state analysis of power electronics circuits. The basic procedure of wavelet approximation is reviewed, and an improved approach by mixing wavelets of different levels is described. When applied to power electronics circuits, the method yields efficient solutions because only a relatively small number of wavelets are needed and the proposed algorithm involves only matrix operations, permitting the steady‐state waveforms to be found fast. Copyright 2003 John Wiley & Sons, Ltd.
Fast‐scale instability in a PFC boost converter under average current‐mode control
Authors: Iu Herbert H. C. , Zhou Yufei , Tse Chi K. 
Published: November 2003

AbstractThis paper investigates the fast‐scale instability in a power‐factor‐correction (PFC) boost converter under a conventional average current‐mode control. The converter is operated in continuous mode. Computer simulations and theoretical analysis are performed to study the effects of the time‐varying input voltage under the variation of some chosen parameters on the qualitative behaviour of the system. It is found that fast‐scale instability may occur during a line cycle, which can cause distortion to the line current and degrade the practical power factor. The results provide useful information for the design of PFC boost converters to avoid distortion due to fast‐scale bifurcation. Copyright © 2003 John Wiley & Sons, Ltd.
Novel aminopropiophenones as potential antidepressants
Authors: Foley Kevin F. , Cozzi Nicholas V. 
Published: November 2003

AbstractThe atypical antidepressant drug bupropion and the psychostimulant drug methcathinone are both members of a chemical class known as aminopropiophenones. Differences in the psychoactive effects of these two drugs result from small variations in their chemical structures, but the relationship between chemical structure and psychoactivity has not been characterized. To investigate how structural modifications to aminopropiophenones affect antidepressant or stimulant activity, we synthesized several analogs of bupropion and methcathinone and tested the new compounds for antidepressant‐like or psychostimulant effects. The synthesized compounds are 2‐(methylamino)‐1‐(3‐bromophenyl)propan‐1‐one (3‐BMAP), 2‐(methylamino)‐1‐(4‐bromophenyl)propan‐1‐one (4‐BMAP), 2‐(iso‐propylamino)‐1‐phenylpropan‐1‐one (i‐PAP), and ‐(tert‐butylamino)‐1‐phenylpropan‐1‐one (t‐BAP). Bupropion, methcathinone, desipramine, and the newly‐synthesized aminopropiophenones were administered to rats for behavioral testing. We used the Porsolt swim test to assess antidepressant‐like activity and a locomotor activity assay to test for psychostimulant effects. All of the compounds displayed antidepressant‐like effects in the Porsolt swim test. Some compounds, including bupropion, increased locomotor activity at moderate‐to‐high doses. A halogenated analog of methcathinone, 4‐BMAP, increased swim time but did not stimulate locomotor activity, even at the highest dose tested. The data indicate that phenyl ring substitution or branched alkylamines can shift the psychopharmacological profile of aminopropiophenones from stimulant activity to antidepressant‐like activity. Several of the new drugs may be effective antidepressants in humans with fewer stimulant‐like side effects compared to bupropion. Drug Dev. Res. 60:252–260, 2003. © 2003 Wiley‐Liss, Inc.