bluuebunny/crossref_metadata_2025_split huggingface dataset:
Khat: pharmacological and medical aspects and its social use in Yemen
Authors: Al‐Motarreb Ahmed , Baker Kathryn , Broadley Kenneth J 
Published: August 2002

AbstractFresh leaves of the khat tree (Catha edulis Forsk.) are chewed for their euphoric properties in East Africa and parts of the Middle East, such as The Yemen. This review describes the history, cultivation and constituents of khat, and the social aspects of khat chewing in Yemen. The major pharmacologically active constituent of the fresh leaves is (−)‐S‐cathinone. The pharmacology of (−)‐S‐cathinone in the central nervous system and the peripheral effects are described. (−)‐S‐Cathinone is regarded as an amphetamine‐like sympathomimetic amine and this mechanism of action is discussed in relation to the central stimulant actions and the cardiovascular effects of increasing blood pressure and heart rate. The risk factors associated with khat chewing are described, with emphasis on the reported increased incidence of acute myocardial infarction. Copyright © 2002 John Wiley & Sons, Ltd.
Hypolipidaemic activity of seaweed from Karachi coast
Authors: Ara Jehan , Sultana Viqar , Qasim Rashida , Ahmad Viqar Uddin 
Published: August 2002

AbstractDuring the present study, ethanol extracts of five seaweed species Solieria robusta, Iyengaria stellata, Colpomenia sinuosa, Spatoglossum asperum and Caulerpa racemosa at 10 mg/ 200 g body weight were tested for their hypolipidaemic activity. All the species significantly decreased the serum total cholesterol, triglyceride and low density lipoprotein cholesterol levels in normal, triton‐induced and diet‐induced hyperlipidaemic rats. Solieria robusta was found to be the most effective in reducing the lipid profile, particularly in diet‐induced hyperlipidaemic rats. A beneficial effect of the ethanol extract of S. asperum was also found on cardiac and liver enzymes in diet‐induced hyperlipidaemic rats. Copyright © 2002 John Wiley & Sons, Ltd.
The acetone soluble fraction from bark extract of Stryphnodendron adstringens (Mart.) Coville inhibits gastric acid secretion and experimental gastric ulceration in rats
Authors: Martins D. T. O. , Lima J. C. S. , Rao V. S. N. 
Published: August 2002

AbstractThe acetone soluble fraction from a crude methanol extract of Stryphnodendron adstringens stem bark (AFSAB) was evaluated in acute (ethanol, indomethacin and hypothermic restraint‐stress) and chronic (acetic acid) models of gastric ulceration and on basal and bethanechol‐stimulated gastric acid secretion in rats. Rats pretreated orally with AFSAB at doses of 400 and 800 mg/kg showed significant decreases of gastric lesion scores in ethanol (62% and 98%) and hypothermic restraint‐stress (89% and 88%) models but exerted no significant influence on indomethacin‐induced acute or acetic acid‐induced chronic ulceration. In pylorus‐ligated rats, AFSAB significantly decreased the basal as well as bethanechol‐stimulated gastric secretory volume and the total acidity with an elevated pH value. AFSAB failed to modify the gastric mucus and the gastric wall nonprotein‐sulphydryl content. These results point to a possible antisecretory effect of AFSAB which account for the observed antiulcer activity in ethanol and hypothermic restraint‐stress induced models of acute gastric ulceration. Copyright © 2002 John Wiley & Sons, Ltd.
Susceptibility of some clinical isolates of Staphylococcus aureus to bioactive column fractions from the lichen Ramalina farinacea (L.) Ach.
Authors: Esimone C. O. , Adikwu M. U. 
Published: August 2002

AbstractThe antimicrobial activities of two bioactive column chromatographic fractions (RF1 and RF2) from the lichen Ramalina farinacea (L.) were evaluated against 15 clinical isolates of Staphylococcus aureus. The susceptibility pattern of the isolates towards tetracycline (TCN) and ampicillin (AMP) was similarly ­evaluated for comparison purposes. The results show that RF1 and RF2 with an MIC90 ( minimum ­inhibitory concentration against 90% of the isolates) of 535.5 and 317 μg/mL respectively, performed generally better than TCN and AMP with an MIC90 of 976.5 and 357 μg/mL respectively. Copyright © 2002 John Wiley & Sons, Ltd.
Ab initio study of the CuPt3 cluster with H2 interaction
Authors: Anguiano A. , Cruz A. , Bertin V. , Poulain E. , Castillo S. 
Published: August 2002

AbstractThe CuPt3 cluster with H2 interaction was studied by means of Hartree–Fock self‐consistent field (HF‐SCF) and multiconfigurational SCF plus variational and multireference second‐order Möller–Plesset perturbational configuration interaction (CIPSI) calculations, using relativistic core potentials. The CuPt3‐H2 interaction was carried out in Cs symmetry for both: the H2 in the Cs reflecting plane and bisected by the Cs reflecting plane. The valence electronic configuration and energy separation of the three low‐lying states of CuPt3 tetrahedral pyramid cluster was determined: 2A″, 2A′, and 4A′ electronic states. We found that the (2A″) ground state captures and dissociates H2 without energy barriers only by a Pt vertex of the CuPt3 cluster. Also, the CuPt3 cluster, in its (2A′) first excited state, by the Cu or Pt center can capture and dissociate the H2 molecule. Meanwhile, the same state for the CuPt2 and Pt3 face can capture and break H2. We have found that CuPt3 cluster in its (4A′) second excited state spontaneously activates and breaks the hydrogen molecule, with some exception, when H2 is approaching to a copper vertex. In this work we found that the CuPt3‐H2 and Pt4‐H2 interactions show similar capture and activation of H2 behaviors such as depth of wells, barriers, adsorption distances, and HH bond relaxation. Even in the case of a single Pt atom substitution by a Cu in a Pt4 cluster, there is no loss of the H2 activity compared with pure metal cluster. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Coherent states for anharmonic diatomic molecules
Authors: Récamier J. , García de León P. , Jáuregui R. , Frank A. , Castaños O. 
Published: August 2002

AbstractIn this work, we construct approximate coherent states for a Morse‐like potential using the displacement operator method and a method recently proposed by Gazeau and Klauder. To test if these states are minimum uncertainty states, we evaluate the temporal evolution of the dispersions in position and momentum. We also construct the trajectories in the phase space and compare with the classic solution. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Improvement of the depth resolution in sputter depth profiling by elastic peak electron spectroscopy
Authors: Kesler V. , Hofmann S. 
Published: August 2002

AbstractSputter depth profiling using elastic peak electron spectroscopy (EPES) is applied to a Ge/Si multilayer structure. The results are evaluated quantitatively using the mixing–roughness–information depth (MRI) model. It is shown that for an elastic peak energy of 1.0 keV the information depth is considerably lower (0.8 nm) compared with that of the Ge LMM (1147 eV) peak (1.6 nm) used in AES depth profiling, resulting in a respectively improved depth resolution for EPES profiling under otherwise similar conditions. Because of the high signal‐to‐noise ratio, EPES depth profiling is successfully applied to measure small diffusion lengths of the order of 1 nm at Ge/Si interfaces. Copyright © 2002 John Wiley & Sons, Ltd.
Imaging XPS investigation of the lateral distribution of copper inclusions at the abraded surface of 2024T3 aluminium alloy and adsorption of decyl phosphonic acid
Authors: Roberts Adam , Engelberg Dirk , Liu Yanwen , Thompson George E. , Alexander Morgan R. 
Published: August 2002

AbstractThe XPS images of copper‐rich intermetallic particles in an aluminium alloy have been obtained after argon ion removal of the oxide at the surface of mechanically polished 2024T3 alloy. Comparison of the XPS analysis before and after etching indicates that the oxide does not include significant concentrations of copper. Through analogy with copper incorporation into anodic films, it is proposed that incorporation into the oxide would only occur after preferential oxidation of aluminium and enrichment of copper immediately below the oxide film.Self‐assembling monolayers of decyl phosphonic acid (DPA) have been adsorbed to the surface of 2024T3 alloy and superpure Al. The lateral distribution was mapped with XPS using the characteristic P 2s signal. The distribution of DPA was relatively uniform on both MS‐Al and 2024T3. This is consistent with the model of the alloy surface constructed from the imaging XPS analysis, which suggests that the oxide on the large particles is close in composition to that on to the surrounding matrix. Copyright © 2002 John Wiley & Sons, Ltd.
Oxygen beam SIMS depth profiling of Si1−xGex layers: transient processes
Authors: Krüger D. , Efremov A. A. , Murota J. , Kurps R. , Bugiel E. , Tillack B. , Romanova G. Ph. 
Published: August 2002

AbstractCharacterization of shallow dopant profiles near surfaces and interfaces in Si1−xGex layers by secondary ion mass spectroscopy (SIMS) is a challenge in advanced Si‐based technologies. In standard SIMS, quantification with confidence is possible only in the dynamic steady state of the measurement after completing a transient period. Therefore, we analyse the transient processes during oxygen bombardment and sputtering of epitaxial Si1−xGex layers, which were grown by low‐pressure chemical vapour deposition (LPCVD) with different compositions (0 < x < 0.75). We show that a drop of the Ge+ secondary ion yield near the end of the transient period in epitaxial Si1−xGex layers extends this period in comparison with pure Si. We demonstrate that the drop is a function of layer composition and bombardment parameters, such as primary ion beam energy and erosion rate. We show that an interfacial transient period after crossing a Si/Si1−xGex interface can be neglected if the formation of the oxygen‐beam‐induced altered layer is completed within the Si cap layer before reaching the interface between the cap and the Si1−xGex layer. This allows reliable quantification of dopant spikes within a few nanometers near to interfaces. By means of computer modelling we describe secondary ion emission kinetics and simulate the dynamics of structural and compositional changes in the subsurface region of Si1−xGex alloys caused by interaction with oxygen beams. Experimental and theoretical time dependencies for secondary ion yields are in good accordance; the dependence of the Ge+ intensity drop on the Ge concentration is simulated and experimentally proved. Copyright © 2002 John Wiley & Sons, Ltd.
A multistate model for the genetic analysis of the ageing process
Authors: Giard Nicole , Lichtenstein Paul , Yashin Anatoli I. 
Published: August 2002

AbstractIn this paper a multivariate frailty model is suggested that can be used in the genetic analysis of the ageing process as a whole, simplified to consisting of the states ‘healthy’, ‘disabled’ and ‘deceased’. The model allows us to evaluate simultaneously the relative magnitude of genetic and environmental influences on frailty variables corresponding to the period of good health and to the life span. The frailty variables can be interpreted as susceptibility to illness or death. The model can be applied to data on groups of related individuals (twins, siblings, a litter). One of the major advantages of this model is that it allows one to include groups of individuals where some or all members of the group are already deceased at the time of observation. The current health status of the living individuals and the exact life span of individuals who are already deceased is the only information necessary for the application of the model. Questions concerning the identifiability of the model based on current health status data and estimation strategies are discussed in the context of specifying the model for twins. Finally, the results of a sample analysis of twin data on prostate cancer are presented. Copyright 2002 John Wiley & Sons, Ltd.
Estimating a treatment effect in survival studies in which patients switch treatment
Authors: Branson Michael , Whitehead John 
Published: August 2002

AbstractFor disease indications such as Acquired Immune Deficiency Syndrome (AIDS) and various cancers, randomization to a pure control treatment may be scientifically desirable but not ethically acceptable. Clinicians may insist that the experimental treatment be made available, at least as a rescue medication, for all patients in the control arm. A method for estimating a treatment effect in survival data from randomized clinical trials of this type is developed under an accelerated failure time model. This approach retains all patients in the groups to which they were randomized and is not based on an ad hoc subgroup analysis. By conditioning on having observed patient switch times, this method avoids the need to model patient switching patterns in the analysis. This new approach is evaluated using simulation studies, and is illustrated through analysing data from a Medical Research Council lung cancer trial. Copyright © 2002 John Wiley & Sons, Ltd.
Assessing the gain in diagnostic performance when combining two diagnostic tests
Authors: Macaskill Petra , Walter Stephen D. , Irwig Les , Franco Eduardo L. 
Published: August 2002

AbstractCombining dichotomous (or dichotomized) results of two diagnostic tests will result in a trade‐off in sensitivity and specificity of the combined test relative to the component tests. Because of this inherent trade‐off, likelihood ratios provide a clinically relevant means of comparing the combined test with one of its components. The likelihood ratios depend on both sensitivity and specificity and hence take into account the trade‐off between them. A graphical approach is used to assess whether the combined test is superior to a component test, or vice versa. Asymptotic standard errors are derived for comparing likelihood ratios when a paired study design is used. The trade‐off in the expected number of additional true positive and false positive results (or true negative and false negative results) is used as the basis for deciding whether to use tests in combination when neither the combined nor a component test shows superior test performance based on their likelihood ratios. These methods are illustrated with an example that considers the combined use of Pap and HPV testing. Copyright © 2002 John Wiley & Sons, Ltd.
Board composition, share ownership, and ‘underpricing’ of U.K. IPO firms
Authors: Filatotchev Igor , Bishop Kate 
Published: August 2002

AbstractUsing a sample of 251 IPOs in the United Kingdom, this paper examines interlinks between executive and nonexecutive characteristics, share ownership, and short‐term performance measured in terms of share offer ‘underpricing.’ It argues that executives' power and previous experience directly affect ex ante choice of nonexecutive directors and their ownership interests in the firm. These endogenously developed governance factors may be used by IPO teams strategically to reduce the extent of underpricing. However, there is a selective response of investors to different board characteristics and share ownership structure. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of hysteretic model on seismic demands: consideration of near‐fault ground motions
Authors: Loh Chin‐Hsiung , Wan Shiuan , Liao Wen‐I 
Published: August 2002

AbstractThis paper summarizes the results of a study that is to evaluate the structural response attributes of near‐fault ground motion. Ground motion recordings from the Chi‐Chi earthquake are used as inputs to the structural system. An improved nonlinear hysteretic model, based on the experimental study, was used to calculate the response of the single degree‐of‐freedom inelastic system. Comparison of the results of analysis with traditional elastic–perfect plastic mode calculations was made. Discussions on the inelastic design spectrum, particularly the code‐specified base shear coefficients, using the improved nonlinear hysteretic model incorporated with the near‐fault input ground motion are made. Copyright © 2002 John Wiley & Sons, Ltd.
Selective combined control stiffness and magnetorheological damping system in nonlinear multistorey structures
Authors: Ribakov Y. , Gluck J. 
Published: August 2002

AbstractThe application of a combined controlled stiffness and magnetorheological (MR) damping system in a base‐isolated nonlinear multistorey structure with amplifying braces is described. Passive control theory is used to obtain the viscous characteristics of the MR damper fluid. Selective control of the proposed system is used to enhance the behaviour of a structure during earthquakes. The nonlinear equations of motion are solved using the Wilson θ method. The control forces are obtained using instantaneous control theory with the predictive control approach. The efficiency of the proposed system is demonstrated by a numerical simulation of a seven‐storey building subjected to four different earthquakes. The stimulation shows that the behaviour of the selective controlled structure with the proposed damping system is significantly improved compared to that of an uncontrolled structure. The energy required for the adjustment of the proposed system with amplifying braces is much lower compared to that of the case of MR dampers connected directly to chevron braces. The response of the predictive controlled structure is close to that of an instantaneous controlled structure. Copyright © 2002 John Wiley & Sons, Ltd.
Critical loads of lateral load resisting structures for tall buildings
Authors: Hoenderkamp J. C. D. 
Published: August 2002

AbstractA simplified hand method of analysis is presented for the calculation of the overall critical load of planar lateral load resisting structures commonly used to provide stability in tall buildings. They may comprise three stiffness components: bending and shear stiffness in addition to a rotational spring stiffness at the base of the structure. The method requires the calculation of three individual critical loads which are then combined to yield the structural critical load. This allows a rapid assessment of second‐order effects on the horizontal displacements and bending moments. The method is most accurate for structures with uniform geometry up the height and is therefore best suited for preliminary stages of design and checking the reasonableness of the results from computer analyses. Copyright © 2002 John Wiley & Sons, Ltd.
SINGLE TREATMENT (HORMONAL IMPRINTING) OF NEWBORN RATS WITH SEROTONIN INCREASES THE SEROTONIN CONTENT OF CELLS IN ADULTS
Authors: Csaba György , Kovács Péter , Pállinger Éva 
Published: August 2002

AbstractHormonal imprinting takes place perinatally at the first encounter between the hormone and its target receptor, causing the finishment of the maturation of receptor—signal transduction system. In the presence of an excess of the target hormone or related molecules faulty imprinting develops with life‐long consequences. In earlier experiments single neonatal treatment with minute dose of IL‐6 caused also prolonged stimulation of IL‐6 production. In the present experiment newborn female and male rats were treated with 20μg serotonin (hormonal imprinting) and were studied for serotonin content of different cell types in adult age. Serotonin content was measured by flow cytometry and its localization was determined by confocal microscopy. Serotonin content was detected in white blood cells (lymphocytes, monocytes and granulocytes); in lymphocytes, monocytes (macrophages), granulocytes and mast cells of peritoneal fluid and thymic lymphocytes. Serotonin was present in all cell types of control animals studied. Serotonin content extremely elevated in the white blood cells and also increased in the peritoneal cells of neonatally treated female animals. There was no elevation in thymic lymphocytes. The mean values of male animals remained at the control level. The experiments call attention to the life‐long effect of the perinatal hormonal imprinting manifested presently in the elevation of serotonin content and point to the gender differences of serotonin imprinting. Considering the role of serotonin in mood and psychiatric diseases, the observations could have some clinical importance.
FRACTIONATION ANALYSIS OF THE ENDOSOMAL COMPARTMENT DURING RAT RETICULOCYTE MATURATION
Authors: Dardalhon Valérie , Géminard Charles , Reggio Hubert , Vidal Michel , Sainte‐Marie Josette 
Published: August 2002

AbstractA subcellular fractionation procedure was developed to isolate the different endosomal compartments present during reticulocyte maturation. After reticulocyte lysis and removal of excess haemoglobin by gel chromatography, membrane vesicles were separated over a discontinuous sucrose gradient (10–40%). Two fractions were isolated: P1 at the 25–35% sucrose interface and P2 at the 17–25% sucrose interface. These fractions were morphologically characterized by electron microscopy and the distribution of endocytic markers in the fractions was detected by Western blot. Moreover, this fractionation technique was used to study the effect of 3‐methyladenine (3‐MA), an autophagy inhibitor, on reticulocyte maturation. The presence of 3‐MA during in vitro maturation of reticulocytes induced a decrease in exosome secretion, as measured by the amount of transferrin receptor (TfR) released in the extracellular medium. The subcellular fractionation results suggested that multivesicular endosome formation from early endosomes is the step affected by 3‐MA.
DIVISION AND DEATH OF CELLS IN DEVELOPING SYNOVIAL JOINTS AND LONG BONES
Authors: Kavanagh Emma , Abiri Mersedeh , Bland Yvette S. , Ashhurst Doreen E. 
Published: August 2002

AbstractArticular chondrocytes are a unique set of cells from the time the cellular condensations that become the anlagen of the long bones develop in the embryo. In the presumptive joint the cells of the opposing bones are packed very closely together, but at cavitation, the central, flattened cells move apart to form the articular surfaces. As the articular cartilage develops the cells are pushed further apart by the cartilaginous matrix. To determine the contributions of cell proliferation and death to cavitation and the subsequent development and growth of articular cartilage, direct observations were made to identify mitotic cells and those with apoptotic bodies in haematoxylin‐stained sections of developing joints, and growing and ageing articular cartilage of the rabbit knee. These observations were extended using antibodies to the proliferating cell nuclear antigen (PCNA) and TdT‐mediated dUTP nick end labelling (TUNEL) on corresponding sections. Low levels of cell division do occur in the articular cartilage up to 6 weeks postnatally, but matrix formation makes the major contribution to the increase in size of the cartilage. Cell death is not observed during cavitation, nor during the development of the articular cartilage proper. Apoptosis is essential, however, for the removal of the epiphyseal cartilage during ossification of the epiphyses and in the growth plate.
INSULIN‐LIKE GROWTH FACTOR‐II INDUCES HYPERTROPHY OF ADULT CARDIOMYOCYTES VIA TWO ALTERNATIVE PATHWAYS
Authors: Huang Chih‐Yang , Hao Ling‐Yang , Buetow Dennis E. 
Published: August 2002

AbstractInsulin‐like growth factor (IGF)‐II is known to induce hypertrophy of isolated adult rat ventricular cardiomyocytes cultured in the absence of serum. However, it is not known how the growth factor exerts this hypertrophic effect. We show here that IGF‐II induces hypertrophy of the cultured cardiomyocytes via two alternative pathways: (1) an IGF‐I receptor‐dependent pathway, or (2) a lysosome‐dependent pathway when the IGF‐I receptor‐dependent pathway is blocked.