bluuebunny/crossref_metadata_2025_split huggingface dataset:
An insight into the mechanism of cytotoxicity of ricin to hepatoma cell: Roles of Bcl‐2 family proteins, caspases, Ca2+‐dependent proteases and protein kinase C
Authors: Hu Rong‐gui , Zhai Qi‐wei , Liu Wang‐yi , Liu Xin‐yuan 
Published: September 2002

AbstractThe ability of ricin, a type II ribosome‐inactivating protein, to induce hepatoma cell (BEL7404) to apoptosis in vitro was examined by fluorescence microscopy, flow cytometry, and DNA fragmentation assay. As a Bcl‐2 lacking model, BEL7404 bore unique advantage to study the effect of over‐expressing Bcl‐2 on the apoptosis induced by the inhibitor of protein synthesis. By establishing a Bcl‐2 over‐expressing cell line (BEL7404/ Bcl‐2), we found that Bcl‐2 could promote the survival of the hepatoma cell against ricin insult. The ricin‐induced apoptosis of BEL7404 was accompanied by increased expression of Bak and decreased levels of Bcl‐xl and Bax. Caspases and PARP cleavage activity were found to be implicated in the death process. Through the inhibitor tests, our results excluded the participation of calcium‐dependent proteases or protein kinase C in the apoptotic process induced by ricin, though an elevation of intracellular calcium did occur as an immediate response to ricin treatment. Cycloheximide, another protein synthesis inhibitor, did synergistically enhance rather than inhibit the cytotoxicity of ricin to hepatoma cell BEL7404. Actually, cycloheximide alone was able to induce hepatoma cell BEL7404 to death that could also be inhibited by over‐expressing Bcl‐2. The elevation of apoptotic protein Bak was discussed to challenge the notion that ricin exerted its cytotoxicity through nonspecific inhibition of all the de novo protein synthesis. J. Cell. Biochem. 81: 583–593, 2001. © 2001 Wiley‐Liss, Inc.
DOIT: a program to calculate thermal rate constants and mode‐specific tunneling splittings directly from quantum‐chemical calculations
Authors: Smedarchina Zorka , Fernández‐Ramos Antonio , Siebrand Willem 
Published: September 2002

AbstractIn this contribution we discuss computational aspects of a recently introduced method for the calculation of proton tunneling rate constants, and tunneling splittings, which has been applied to molecules and complexes, and should apply equally well to bulk materials. The method is based on instanton theory, adapted so as to permit a direct link to the output of quantum‐chemical codes. It is implemented in the DOIT (dynamics of instanton tunneling) code, which calculates temperature‐dependent tunneling rate constants and mode‐specific tunneling splittings. As input, it uses the structure, energy, and vibrational force field of the stationary configurations along the reaction coordinate, computed by conventional quantum‐chemical programs. The method avoids the difficult problem of calculating the exact least‐action trajectory, known as the instanton path, and instead focusses on the corresponding instanton action, because it governs the dynamic properties. To approximate this action for a multidimensional system, the program starts from the one‐dimensional instanton action along the reaction coordinate, which can be obtained without difficulty. It then applies correction terms for the coupling to the other vibrational degrees of freedom, which are treated as harmonic oscillators (transverse normal modes). The couplings are assumed linear in these modes. Depending on the frequency and the character of the transverse modes, they may either decrease or increase the action, i.e., help or hinder the transfer. A number of tests have shown that the program is at least as accurate as alternative programs based on transition‐state theory with tunneling corrections, and is also much less demanding in computer time, thus allowing application to much larger systems. An outline of the instanton formalism is presented, some new developments are introduced, and special attention is paid to the connection with quantum‐chemical codes. Possible sources of error are investigated. To show the program in action, calculations are presented of tunneling rates and splittings associated with triple proton transfer in the chiral water trimer. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 787–801, 2001
Renal infarct: Contrast‐enhanced power Doppler sonographic findings
Authors: Yücel Cem , Özdemir Hakan , Akpek Sergin , Gürel Kamil , Kapucu L. Özlem , Araç Mehmet 
Published: September 2002

AbstractPower Doppler sonography (PDUS) is a promising technique for the diagnosis of renal infarcts. PDUS's efficacy may be enhanced by using sonographic contrast agents. We evaluated 3 cases of renal infarction using PDUS and the sonographic contrast agent Levovist. The findings were compared with those of other imaging modalities, such as scintigraphy, CT, and angiography. In case 1, PDUS showed a patent interlobar artery only in the lower part of the right kidney and no other perfusion of the right renal parenchyma. Contrast‐enhanced PDUS showed patchy areas of preserved perfusion in the lower and middle‐upper anterior portions of the kidney. In case 2, PDUS showed diffuse and patchy perfusion defects in the anterolateral portion of the right kidney. On contrast‐enhanced PDUS, no signal enhancement was seen in these areas, but the perfusion defects were better delineated. In case 3, PDUS showed no perfusion in the upper pole of the kidney; the nonperfused area extended to the posterior upper portion of the kidney but could not be distinguished from normal tissue. After injection of the contrast agent, there was no enhancement of the posterior extension of the upper pole infarct, but Doppler signals from the surrounding normal parenchyma were enhanced, so the area was more clearly demarcated. The administration of the contrast agent facilitated the visualization of the infarcts in all 3 cases. © 2001 John Wiley & Sons, Inc. J Clin Ultrasound 29:237–242, 2001.
Ciliary protein turnover continues in the presence of inhibitors of golgi function: Evidence for membrane protein pools and unconventional intracellular membrane dynamics
Authors: Stephens Raymond E. 
Published: September 2002

AbstractThe intimate association of the Golgi apparatus with cilia suggests a functional alliance. To explore the relationship between the synthesis and processing of membrane constituents and the turnover or regeneration of cilia, parallel cultures of gastrula‐stage sea urchin embryos were pulse‐chase labeled with 3H‐leucine in the presence of monensin, brefeldin A, or colchicine. Steady‐state labeled cilia were isolated, and the embryos were allowed to regenerate cilia, which were then isolated after the equivalent of two normal regeneration times. Regeneration was absent in colchicine, minimal in monensin, and inhibited about 40% by brefeldin A. Both monensin and brefeldin A effectively inhibited the post‐translational processing of prominent phosphatidylinositoylated and palmitoylated membrane proteins and the axoneme‐associated transmembrane Spec3 protein, yet most other membrane plus matrix and 9+2 axonemal proteins were labeled to levels indistinguishable from untreated controls. However, total protein analysis of the membrane plus matrix fractions showed a substantial increase in glycoproteins and the calsequestrin‐like protein ECaSt/PDI after treatment at steady‐state with all three inhibitors and after regeneration in brefeldin A. Other constituents of this compartment, such as membrane‐associated tubulin, calmodulin, and a 53‐kDa calcium‐binding protein, were unchanged. Therefore, inhibition of Golgi function via three different mechanisms left 9+2 protein turnover undiminished but resulted in an accumulation, in the cilium, of already‐processed membrane pool constituents and a normally ER‐resident protein. A disproportionate elevation of HSP70 suggests that a novel stress response may be involved in inhibiting ciliary regeneration or promoting glycoprotein augmentation. J. Exp. Zool. 289:335–349, 2001. © 2001 Wiley‐Liss, Inc.
Fiscal federalism and government size in transition economies: the case of Moldova
Authors: De Mello Luiz 
Published: September 2002

AbstractThis paper examines the relationship between fiscal decentralization—the assignment of revenue sources and expenditure functions across government levels—and government size in Moldova. The empirical results—based on data for a cross‐section of Moldovan sub‐national government in 1998—suggest that fiscal decentralization is associated with larger sub‐national governments and that the country's revenue‐sharing system imposes a constraint on sub‐national revenue mobilization capacity. Copyright © 2001 John Wiley & Sons, Ltd.
Molecularly imprinted polymers from nicotinamide and its positional isomers
Authors: Fu Qiang , Zheng Ning , Li Yuan Zong , Chang Wen Bao , Wang Zong Mu 
Published: September 2002

AbstractImprinted polymers were prepared for nicotinamide and its positional isomers. The influence of porogenic solvent and functional monomer on recognition properties of the polymer was compared. The results indicated that two functional groups, the heterocyclic nitrogen and the amide group, in the nicotinamide or isonicotinamide molecule have a synergistic effect in binding to the polymer. The polymers prepared with nicotinamide and isonicotinamide can be used as HPLC stationary phase for the separation of positional isomers of nicotinamide or isonicotinamide, while the polymer prepared with picolinamide showed no specificity toward the template. The mechanisms for the differences in recognition are discussed. In addition to the retention of polymers to their templates the polymers also displayed excellent retention to nicotinic acid and isonicotinic acid, compounds structurally similar to the template. This dual recognition property of the polymer may be useful in circumstances where the preparation of a polymer for a specific template may be problematic because of poor stability or solubility. Copyright © 2001 John Wiley & Sons, Ltd.
Abbreviations used:

AIBN

2,2′‐azo‐bis‐iso‐butyronitrile

EGDMA

ethylene glycol dimethacrylate

HPLC

high performance liquid chromatography

MAA

methacrylic acid

MIPs

molecular imprinted polymers

NAM

nicotinamide.
Analysis of maximum and minimum daily temperatures recorded at Fabra Observatory (Barcelona, NE Spain) in the period 1917–1998
Authors: Serra C. , Burgueño A. , Lana X. 
Published: September 2002

AbstractDaily maximum and minimum temperatures recorded without interruption at Fabra Observatory (Barcelona) from 1917 to 1998 are analysed studying their homogeneity, randomness, possible trends and their statistical significance, and time irregularities detected by means of concepts of entropy and spectral power analysis. The homogeneity of the series is tested on a monthly scale using the adaptive Kolmogorov–Zurbenko filter. With respect to the randomness of the time series, the von Neumann ratio test is applied to standardized values of extreme temperatures in four different time‐scales (daily, monthly, seasonal and annual). The statistical significance of trends is quantified by applying the Spearman and Mann–Kendall tests to daily, monthly and seasonal data. The Mann–Kendall sequential test also leads to the detection of sharp changes in the time series when monthly data is analysed. The quantification of irregularities through entropy is investigated for standardized temperatures on daily, monthly and seasonal scales, based on the concept of mathematical information theory. Periodicities derived from spectral power analyses are checked with the hypothesis of white‐noise and Markov red‐noise stochastic processes. The most notable features, common to maximum and minimum temperatures, are the lack of randomness of the series for all the time‐scales considered and the different trends obtained for the periods 1917–1980 and 1917–1998, which are confirmed by the Spearman and sequential Mann–Kendall tests. Nevertheless, the maximum and minimum temperature series show quite a different behaviour from the point of view of results concerning time irregularities in terms of entropy and periodicities. The main features of the results are discussed by comparing them with those obtained for other areas of the Mediterranean domain. Copyright © 2001 Royal Meteorological Society
Spatial distribution of seasonal rainfall trends in a western Mediterranean area
Authors: González‐Hidalgo J.C. , De Luis M. , Raventós J. , Sánchez J.R. 
Published: September 2002

AbstractChanges in seasonal patterns of rainfall are key ecological factors. The definition of the spatial scale on which these changes can occur is particularly relevant in Mediterranean areas, where problems related to the variability of the pluviometric regime vary from one place to another. The region of Valencia is a good example of this kind of variability in rainfall regimes. To study changes in seasonal means and variability, we have applied non‐parametric (Spearman test) and parametric techniques (linear model) to data from 97 pluviometric stations during the World Meteorological Organization (WMO) normal period, 1961–1990. Special emphasis has been placed on the analysis of the spatial pattern of trends in means and variability. For this purpose, we have used a modified version of the Cramér–von Mises test in order to define subregional areas with similar rainfall evolution. Our results show a high spatial heterogeneity in rainfall evolution. The striking feature is the progressive dryness in the autumn season accompanied by an increase in interannual variability. Increases in winter and summer interannual variability, and decreases in rainfall amounts in winter are dominant too. We discuss these results in relation to rainfall generation mechanisms and their ecological implications. Copyright © 2001 Royal Meteorological Society
20th century droughts in southern Africa: spatial and temporal variability, teleconnections with oceanic and atmospheric conditions
Authors: Richard Yves , Fauchereau Nicolas , Poccard Isabelle , Rouault Mathieu , Trzaska Sylwia 
Published: September 2002

AbstractSouthern African rainfall does not show any trend to desiccation during the 20th century. However, the subcontinent experienced particularly severe droughts in the 1980s and at the beginning of the 1990s and the magnitude of the interannual summer rainfall variability shows significant changes. Modifications of the intensity and spatial extension of droughts is associated with changes in ocean–atmosphere teleconnection patterns.This paper focuses mostly on the well‐documented 1950–1988 period and on late summer season (January–March). A principal component analysis on southern African rainfall highlights modifications of the rainfall variability magnitude. The 1970–1988 period had more variable rainfall, and more widespread and intense droughts than the 1950–1969 period.To investigate the potential modifications of the associated ocean–atmosphere teleconnection patterns, a composite analysis is performed on sea‐surface temperature (SST) and National Center for Environmental Protection (NCEP) atmospheric parameters, according to the 5 driest years of both sub‐periods. Significant changes are shown in ocean–atmosphere anomaly patterns coincident with droughts for both sub‐periods. The 1950–1969 droughts were associated with regional ocean–atmosphere anomalies, mainly over the southwest Indian Ocean region. In contrast, during the 1970–1988 droughts near‐global anomalies were observed in the tropical zone, corresponding to El Niño–Southern Oscillation (ENSO) phenomenon.Within the whole century, significant correlations between Southern Oscillation Index (SOI) and southern African Rainfall Index (SARI) were found in the periods (1900–1933 and 1970–1998) when SOI and SARI experienced high variability, and when southern Africa was affected by intense and extended droughts. During periods of low SOI (1934–1969), correlations became less significant and droughts were less intense and widespread. Copyright © 2001 Royal Meteorological Society
Degradation and metabolism of 14C‐labelled proanthocyanidins from carob (Ceratonia siliqua) pods in the gastrointestinal tract of the rat
Authors: Abia Rocío , Fry Stephen C 
Published: September 2002

AbstractThe aim of the work was to study the binding, degradation and metabolism of dietary condensed tannins in the gastrointestinal tract of an omnivore. Young pods of carob (Ceratonia siliqua L) were radiolabelled by in vivo feeding of 14CO2, trans‐[U‐14C]cinnamate or L‐[U‐14C]phenylalanine. [14C]Proanthocyanidins (condensed tannins) were extracted with acetone/water (3:1 v/v), isolated on Sephadex LH‐20 and fed to rats by gavage. After 4 and 18 h, 90–94% of the gavaged 14C was in the gut contents and/or faeces. Much of the gavaged 14C (57%), predominantly that originally in tannins of high degree of polymerisation (DP), became insolubilised, mainly in the form of protein–tannin complexes. Some of the [14C]tannins that remained soluble decreased in DP, especially in the small intestine and caecum. A further fraction (12% of the 14C gavaged) underwent chemical modifications in the gut to form soluble, non‐tannin compounds. Small proportions of the 14C were found in the liver (1.0–1.5%), urine (1–2%) and 14CO2 (1–2%). We conclude that proanthocyanidins are not inert within the gut but undergo various modifications which may affect the nutrition of the animal.© 2001 Society of Chemical Industry
The mechanism of neutral amino acid decomposition in the gas phase. The elimination kinetics of N,N‐dimethylglycine ethyl ester, ethyl 1‐piperidineacetate, and N,N‐dimethylglycine
Authors: Ensuncho Adolfo , Lafont M. Jennifer , Rotinov Alexandra , Domínguez Rosa M. , Herize Armando , Chuchani Gabriel , Quijano Jairo 
Published: September 2002

AbstractThe gas‐phase elimination kinetics of the ethyl ester of two α‐amino acid type of molecules have been determined over the temperature range of 360–430°C and pressure range of 26–86 Torr. The reactions, in a static reaction system, are homogeneous and unimolecular and obey a first‐order rate law. The rate coefficients are given by the following equations. For N,N‐dimethylglycine ethyl ester:
log k1(s−1) = (13.01 ± 3.70) − (202.3 ± 0.3)kJ mol−1 (2.303 RT)−1
For ethyl 1‐piperidineacetate:
log k1(s−1) = (12.91 ± 0.31) − (204.4 ± 0.1)kJ mol−1 (2.303 RT)−1
The decompositon of these esters leads to the formation of the corresponding α‐amino acid type of compound and ethylene. However, the amino acid intermediate, under the condition of the experiments, undergoes an extremely rapid decarboxylation process. Attempts to pyrolyze pure N,N‐dimethylglycine, which is the intermediate of dimethylglycine ethyl ester pyrolysis, was possible at only two temperatures, 300 and 310°C. The products are trimethylamine and CO2. Assuming log A = 13.0 for a five‐centered cyclic transition‐state type of mechanism in gas‐phase reactions, it gives the following expression: log k1(s−1) = (13.0) − (176.6)kJ mol−1 (2.303 RT)−1. The mechanism of these α‐amino acids differs from the decarbonylation elimination of 2‐substituted halo, hydroxy, alkoxy, phenoxy, and acetoxy carboxylic acids in the gas phase. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33:465–471, 2001
Factorial design analysis of the catalytic activity of di‐imine copper(II) complexes in the decomposition of hydrogen peroxide
Authors: Alves W. A. , De Almeida Azzellini M. A. , De Costa Ferreira A. M. , Bruns R. E. 
Published: September 2002

AbstractFactorial design analysis was applied to the study of the catalytic activity of di‐imine copper(II) complexes, in the decomposition of hydrogen peroxide. The studied complexes show a tridentate imine ligand (apip), derived from 2‐acetylpyridine and 2‐(2‐aminoethyl)pyridine, and a hydroxo or an imidazole group at the fourth coordination site of the copper ion. The factorial design models for both [Cu(apip)imH]2+ and [Cu(apip)OH]+ were similar. Increasing the peroxide concentration from 3.2 × 10−3 to 8.1 × 10−3 mol L−1 resulted in increased oxygen formation. Increasing the pH from 7 to 11 also increased oxygen formation and had an effect about twice as large as the peroxide one. Both complexes also had an important interaction effect between peroxide concentration and pH. However, increasing the catalyst concentration led to a decrease in total oxygen formation. The obtained results were corroborated by further data, achieved by using the usual univariate method, and helped to elucidate equilibrium steps occurring in the studied systems. In very alkaline solutions, the studied [Cu(apip)imH]2+ complex can form the corresponding dinuclear species, [Cu2(apip)2im]3+. While the mononuclear complex proved to be an efficient catalyst in hydrogen peroxide decomposition, the corresponding dinuclear compound seemed to be able to coordinate with the dioxygen molecule, inhibiting its observed release. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 472–479, 2001
Parametric and temperature‐sensitivity study of resonance frequency of microstrip antennas using spectral‐domain method
Authors: Kedar Ashutosh , Gupta K. K. , Srivastava G. P. , Kataria N. D. 
Published: September 2002

AbstractIn the present paper, a study is carried out to visualize the effects of various design parameters, including temperature, on the resonant frequency of a microstrip patch antenna. The analysis is carried out using the spectral‐domain method with efficient evaluation of infinite 2‐D reaction integrals improving the rate of convergence. Some of the numerical results are compared with the experimental data. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 276–280, 2001.
Silicon‐29 NMR study of the formation of monomethoxysilicic acid in methanolic alkaline silicate solutions
Authors: Samadi‐Maybodi Abdolraouf , Harris Robin K. , Naser Azizi S. , Kenwright Alan M. 
Published: September 2002

AbstractSilicon‐29 NMR spectra were obtained for more than 20 aqueous alkaline silicate solutions containing methanol. A signal assigned to CH3OSi(OH)3 or one of its deprotonated congeners was studied in detail for the first time for the solution conditions involved. Its appearance was monitored as a function of the solution compositions. The pseudo‐equilibrium constant for its formation is of the order of 0.65. Copyright © 2001 John Wiley & Sons, Ltd.
Requirement of cyclin B2, but not cyclin B1, for bipolar spindle formation in frog (Rana japonica) oocytes
Authors: Kotani Tomoya , Yoshida Noriyuki , Mita Koichi , Yamashita Masakane 
Published: September 2002

AbstractCyclin B, the regulatory subunit of maturation‐promoting factor (MPF), comprises several subtypes that are presumed to confer different functions on MPF although no direct evidence has been provided to date. To clarify the difference in the roles of cyclins B1 and B2, we used frog (Rana japonica) oocytes in which MPF is formed only after progesterone stimulation because it is possible to produce oocytes containing either cyclin B1‐MPF or cyclin B2‐MPF by antisense RNA‐mediated translational inhibition of each mRNA. Using this advantage, we investigated the functions of cyclins B1 and B2 and obtained the following results: (a) oocytes synthesizing cyclin B2‐MPF underwent meiosis I and II with formation of a bipolar spindle at each metaphase; (b) oocytes synthesizing cyclin B1‐MPF formed a monopolar spindle at metaphase I and extruded an abnormal polar body; and (c) both oocytes underwent germinal vesicle breakdown (GVBD) and chromosome condensation. Immunocytochemical observations also revealed continuous localization of cyclin B2 on the spindle during meiosis. These results provide evidence of the requirement of cyclin B2, but not cyclin B1, for organizing the bipolar spindle, though either cyclin B1 or B2 is redundant for inducing GVBD and chromosome condensation. Mol. Reprod. Dev. 59:199–208, 2001. © 2001 Wiley‐Liss, Inc.