bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of gas‐phase molecular recognition using Fourier transform ion cyclotron resonance mass spectrometry (FTICR/MS)
Authors: Dearden David V. , Liang Yongjiang , Nicoll Jeremy B. , Kellersberger Katherine A. 
Published: August 2002

AbstractThe application of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to the quantitative study of molecular recognition in the gas phase is reviewed. Because most quantitative measurements are dependent on accurate determination of the pressure of a neutral reagent, methods for accurate pressure measurement in FTICR, including gauge calibration using a reaction with known rate constants (the traditional method), exothermic proton transfer rate measurement (often the best method when accurate neutral pressures in the trapping cell are desired), and linewidth measurement (a little‐used, but generally applicable method) are discussed. The use of rate constant measurements in molecular recognition is illustrated with examples employing natural abundance isotopic labeling to study self‐exchange and 2 : 1 ligand:metal complex formation kinetics in crown ether–alkali cation systems. Self‐exchange rates do not correlate with alkali cation/crown cavity size relationships, whereas 2 : 1 complex formation kinetics correlate strongly with size relationships. The use of exchange equilibrium constant measurements to characterize molecular recognition is illustrated by alkali cation exchanges between 18‐crown‐6 and the isomers of dicyclohexano‐18‐crown‐6. These experiments show that the alkyl‐substituted ligand binds alkali cations better than unsubstituted 18‐crown‐6 in the gas phase, in accordance with expectations based on the higher polarizability of the alkyl‐substituted ligand. Further, the metal binding thermochemistry differs for the two dicyclohexano‐18‐crown‐6 isomers, with the bowl‐shaped cis–syn‐cis isomer binding all the alkali cations more strongly than the cis–anti‐cis isomer. The measurement of entropies and enthalpies associated with one of the most subtle forms of molecular recognition, enantiomeric discrimination, is illustrated by studies of the discrimination between enantiomers of chiral amines by dimethyldiketopyridino‐18‐crown‐6. This chiral ligand binds chiral primary ammonium cations that have the opposite absolute configuration at their stereocenter more strongly than the enantiomer with the same absolute configuration. Gas‐phase studies show that this enantiomeric discrimination is enthalpic in origin, likely related to more favorable π–π stacking for the preferred enantiomer. Entropy disfavors binding of the preferred enantiomer. Copyright © 2001 John Wiley & Sons, Ltd.
Change in hepatitis A virus seroepidemiology in southern Taiwan: a large percentage of the population lack protective antibody
Authors: Wang Shih‐Min , Liu Ching‐Chuan , Huang Yi‐Shen , Yang Yao‐Jong , Lei Huan‐Yao 
Published: August 2002

AbstractHepatitis A, the predominant reported etiologic form of viral hepatitis in Taiwan, continues to be a disease primarily of children and young adults. A seroepidemiologic study was performed to assess the seroprevalence of hepatitis A (HAV) antibodies in the southern Taiwan general population in 1998 and is compared with results of a similar study in 1992. A total of 948 subjects (477 male and 471 female) with ages ranging from 0.3 to 63 years were stratified into 14 age‐specific groups. The presence of anti‐HAV antibodies was detected using a commercially available radioimmunoassay. Fifteen percent of the subjects were positive for anti‐HAV antibodies, which is lower than that in 1992 (P < 0.001). Seroprevalences were 14.1% for males and 22.6% for females (P = 0.006). The pattern of anti‐HAV seroprevalence was distinguishable from that found in 1992; minimum seroconversion occurred at ages ranging from 1 to 30 years. Prevalence of seropositive subjects decreased markedly for the < 1, 13–15, 16–19, 20–24, 25–29, and 30–39 year age groups in comparing 1998 with 1992. The current study demonstrates a continuing decline in the prevalence of HAV among children, adolescents, and young adults. The findings can be ascribed to the improvement of socioeconomic status and modernization of environmental sanitation. As a consequence of this changing trend of endemicity and the resulting lack hepatitis A antibodies among the general population in Taiwan, the risk of sudden major outbreaks is increased because of increasing international travel and immigration, particularly during and after natural disasters. HAV vaccination will be important for the prevention and control of HAV outbreaks in the community. J. Med. Virol. 64:104–108, 2001. © 2001 Wiley‐Liss, Inc.
Dendritic cell susceptibility to hepatitis C virus genotype 1 infection
Authors: Navas Maria‐Cristina , Fuchs Anne , Schvoerer Evelyne , Bohbot Alain , Aubertin Anne‐Marie , Stoll‐Keller Françoise 
Published: August 2002

AbstractIn vitro infection of human monocyte‐derived dendritic cells was carried out to study their susceptibility to hepatitis C virus (HCV) infection. Immature dendritic cells and mature dendritic cells were incubated overnight at 37°C with HCV‐positive (genotype 1) serum samples; the presence of the viral genome associated with the production of its replicative intermediate was used as evidence of infection. In immature dendritic cells, HCV RNA was detectable from days 1–10 post‐infection (p.i.), and de novo synthesis of negative‐strand HCV RNA could be demonstrated by a strand‐specific rTth reverse transcription‐polymerase chain reaction at day 2. In mature dendritic cells, the positive‐strand form was detectable from days 1–5 p.i., while the negative‐strand HCV RNA appeared at days 1 and 2 p.i. Quasispecies present in the inoculum and 6 days p.i. were analyzed by sequencing hypervariable region 1 of the E2 protein. Only two of seven HVR variants present in the inoculum were found in HCV‐infected immature dendritic cells. Another two HVR variants not found in the inoculum were recovered from infected immature dendritic cells, suggesting serum minor variants selection or virus evolution during in vitro replication. Analysis by single‐strand conformation polymorphism assay of 5′ untranslated region of HCV sequences showed that the patterns obtained from the inoculum and infected immature dendritic cells and mature dendritic cells differed slightly. These findings indicate that both immature dendritic cells and mature dendritic cells are susceptible to HCV genotype 1 infection, supporting at least HCV RNA replication. This model should be a valuable tool for the study of modulation of dendritic cell functions in HCV infection. J. Med. Virol. 67:152–161, 2002. © 2002 Wiley‐Liss, Inc.
Characterization of Norwalk‐like virus associated with gastroenteritis in Indonesia*
Authors: Subekti D.S. , Tjaniadi P. , Lesmana M. , Simanjuntak C. , Komalarini S. , Digdowirogo H. , Setiawan B. , Corwin A.L. , Campbell J.R. , Porter K.R. , Oyofo B.A. 
Published: August 2002

AbstractNorwalk Virus and Norwalk‐like viruses (NLVs) are reportedly responsible for 2.5–4.0% of nonbacterial acute gastroenteritis (NBAG) worldwide. To help clarify the impact of NLVs on NBAG in Indonesia, stool specimens from 102 patients, 74 with NBAG and 28 with BAG, were screened for the presence of NLVs, using a reverse transcription‐polymerase chain reaction (RT‐PCR) assay. The specimens were subtyped using prototype‐specific oligonucleotide probes and were sequenced and compared with published NLV sequences. Of the 102 specimens examined, 31 (30%) were found to be positive for NLVs. Type‐specific probe analysis of the RT‐PCR products indicated that 31 isolates hybridized to UK1 (Taunton agent) and UK3/4 (Hawaii agent/Snow Mountain agent) prototype strains. The results of this study indicate that prototype strains of NV or NLVs co‐circulate in Indonesia and contribute to the overall level of acute gastroenteritis throughout the region. J. Med. Virol. 67:253–258, 2002. © 2002 Wiley‐Liss, Inc.
Impaired sensory function in heterozygous P0 knockout mice is associated with nodal changes in sensory nerves
Authors: Samsam M. , Frei R. , Marziniak M. , Martini R. , Sommer C. 
Published: August 2002

AbstractMice heterozygously deficient in the major myelin component P0 are an established model of an inherited neuropathy and show signs of myelin degeneration in motor nerves. Unlike the case in patients, the sensory nerves are only mildly affected in the mouse mutants and do not show features indicative of myelin degeneration. Unexpectedly, by applying established behavioral tests, we found sensory deficits, as reflected by raised withdrawal thresholds to mechanical and thermal stimuli, whereas behavioral signs of a painful neuropathy were not detectable. By electron microscopy of longitudinal sections of sensory nerves, we found abnormalities in nodes of Ranvier comprising enlarged nodal gaps and poorly developed nodal Schwann cell microvilli. These alterations might be causally linked to the sensory deficits in the absence of profound myelin degeneration in the sensory nerves of the mutants. © 2002 Wiley‐Liss, Inc. © 2002 Wiley‐Liss, Inc.
Evidence for a localization of [3H]nociceptin binding sites on medullar primary afferent fibers
Authors: Le Cudennec C. , Suaudeau C. , Costentin J. 
Published: August 2002

AbstractThe ORL1 receptor (opioid receptor‐like 1) and its endogenous ligand, nociceptin, are involved in nociperception. We have studied, in a deafferented animal model, the modification of medullar [3H]nociceptin binding site density. A rhizotomy was carried out in rats at the cervicothoracic level, and the dorsal afferent fibers from C5 to T1 were lesioned. Seven days after surgery, animals were sacrificed, and the binding of [3H]nociceptin (2 nM) was then performed on spinal cord sections. An autoradiographic analysis revealed a significant reduction (–18%) of [3H]nociceptin binding site density in the dorsal horn ipsilateral to the deafferentation compared with the contralateral side of the lesion. In the ventral horn, no significant difference (–5%) of binding was observed in the ipsilateral side of the deafferentation compared with the contralateral side. Thus, [3H]nociceptin binding sites appear to be located mainly on either interneurons or deutoneurons of the spinal cord, because the bulk of the labeling is spared by the lesion. However, the significant reduction of labeling that occurs on the dorsal part of the ipsilateral side to the lesion indicates that [3H]nociceptin binding sites are also present on these dorsal afferent fibers. © 2002 Wiley‐Liss, Inc.
Glutamine as a pathogenic factor in hepatic encephalopathy
Authors: Albrecht Jan , Dolińska Monika 
Published: August 2002

AbstractHepatic encephalopathy (HE) results from acute or chronic liver dysfunction and is associated with hyperammonemia. Ammonium ions penetrate from blood to brain, where they form glutamine (Gln) in the reaction with glutamate catalyzed by an astroglia‐specific enzyme, glutamine synthetase (GS). Experimental data suggest that many manifestations of HE can be ascribed to increased Gln synthesis and accumulation in the brain. In HE resulting from acute liver failure (“fulminant hepatic failure”), the osmotic action of Gln appears to be in a large degree responsible for cerebral edema and edema‐associated disturbances of cerebral blood flow and ionic homeostasis. In chronic HE not accompanied by cerebral edema, Gln contributes to impairment of cerebral energy metabolism, and its increased transport from brain to the periphery accelerates the blood‐to‐brain transport of aromatic amino acids, of which tryptophen (Trp) is converted to metabolites directly implicated in HE. Most of the evidence that Gln participates in pathological events has been derived from their disappearance or amelioration in HE rats in which the cerebral Gln content was reduced by treatment with a GS inhibitor, methionine sulfoximine. J. Neurosci. Res. 65:1–5, 2001. © 2001 Wiley‐Liss, Inc.
Cysteine dioxygenase: Regional localisation of protein and mRNA in rat brain
Authors: Parsons R.B. , Waring R.H. , Williams A.C. , Ramsden D.B. 
Published: August 2002

AbstractCysteine dioxygenase (CDO) converts cysteine to cysteinesulphinic acid and is the rate‐limiting step in sulphate production. Most studies have centred upon the hepatic form of the enzyme, but several studies have investigated brain CDO using activity assays and western blotting. The aim of this study was to investigate the expression of CDO in the rat brain using a combination of immunohistochemistry and in situ hybridisation. Affinity‐purified anti‐R and anti‐H CDO antibodies were immunoprecipitated using rat brain homogenate to determine whether the antibodies could remove enzyme activity. Immunohistochemistry and in situ hybridisation were then used to determine the cellular and regional expression of both CDO protein and mRNA. Immunoprecipitation of rat brain homogenate removed up to 98% and 70% (anti‐R and anti‐H, respectively) of enzyme activity. Nonimmune sheep serum had no effect upon enzyme activity. CDO protein and mRNA was localised solely to the neurones of the brain, including the pyramidal cells of the hippocampus and the Purkinje cells of the cerebellum. Regional localisation varied, with high levels of expression in the hippocampus, the dentate gyrus, the outer cortices of the brain, and the substantia nigra. The relative expression of CDO activity and protein in these regions is most probably a result of the relative abundance of neurones in these regions. CDO expression in the brain may have several possibile functions, the most likely being the prevention of free radical production by the autoxidation of cysteine and dopamine. J. Neurosci. Res. 65:78–84, 2001. © 2001 Wiley‐Liss, Inc.
A transient form of 2-aza-21-carbaporphyrin prearranged for fusion: DFT studies
Authors: SZTERENBERG LUDMIŁA , LATOS-GRAŻYŃSKI LECHOSŁAW 
Published: August 2002

The formation mechanism of the fused porphyrin (CTPPH-NF) involves a rotation of the N(2) pyrrole ring of 2-aza-21-carba-5,10,15,20-tetraarylporphyrin (CTPPH2) which is subsequently followed by formation of the C(3)–N(24) bond to yield the macrocycle with the fused pyrrole tripentacyclic ring. To approach the problem of the relative stability of the prearranged transient species theoretical investigations have been performed applying density functional theory (DFT). The molecular structures and electronic energy have been studied for idealized 2-aza-21-carbaporphyrin (CPPH2) and porphyrin (PH2) macrocycles created by a replacement of phenyl or other substituents with hydrogen or methyl groups. The following forms of 2-aza-21-carbaporphyrin and porphyrin were studied: CPH2-I, 2-NH-CPH-I and PH2-I in relation to CPH2-P, 2-NH-CPH-P and PH2-P, respectively (P indicates regular geometry (N(21) or C(21) located in the inner perimeter) and I indicates inverted geometry (N(21) or C(21) located in the outer perimeter). A π delocalization exists through the inverted macrocycles: PH2-I, CPH2-I and 2-NH-CPH-I. The B3LYP/6-31G** optimized bond distances of I macrocycles reproduce the pattern of the P counterparts. The B3LYP/6-31G**//B3LYP/6-31G** calculated energy differences between the P and I structures are very similar for two considered 2-aza-21-carbaporphyrin tautomers: CPH 2-P → CPH 2-I, 18.50 kcal mol-1, 2- NH - CPH -P → 2- NH - CPH -I, 17.55 kcal mol-1; but essentially different for the regular porphyrin PH2-P → PH 2-I, 45.56 kcal mol-1. The methyl substitution at the 21-carbon or 5 and 20 meso positions preserved the order of stability as the calculated energy differences equal 21- CH 3- CPH 2-P → 21- CH 3- CPH 2-I, 13.39 kcal mol-1; 5,20- CH 3- CPH 2-P → 5,20- CH 3- CPH 2-I, 17.87 kcal mol-1.
Palaeoenvironmental significance of the mammalian faunas of Italy since the Pliocene
Authors: Montuire Sophie , Marcolini Federica 
Published: August 2002

AbstractThe evolution of mammalian communities is a significant tool for reconstructing past environments and climate. In this paper, a palaeoecological and palaeoenvironmental reconstruction based on the study of the Italian mammal faunas ranging from Middle Pliocene to the Holocene is presented using the cenogram method and quantification of temperatures based on arvicolid species richness. These analyses reveal open and arid conditions during glacial periods and less open and more humid conditions during interglacials, with some differences between north and central–south Italy. Northern and Southern communities reflect similar trends in the evolution of palaeoenvironments and in the variation of the temperatures, but differences in estimated temperatures, which indicate a more temperate climate for southern Italy throughout the period, are considered here. Copyright © 2002 John Wiley & Sons, Ltd.
Green function method and its application to the resonance Raman effect
Authors: Ovander L. N. , Shadura V. A. 
Published: August 2002

AbstractThe advantages of the Green function method for considerations in resonant Raman scattering are shown. It is possible to avoid difficulties which arise when the frequency of incident light is in the excitonic absorption band. Copyright © 2001 John Wiley & Sons, Ltd.
Study of solvent effects on the molecular structure and the reorganization energies of 4‐nitro‐4′‐dimethylaminoazobenzene using resonance Raman intensities
Authors: Biswas Nandita , Umapathy Siva 
Published: August 2002

AbstractResonance Raman spectroscopy was used to probe the effect of solvent polarity on the molecular structure and isomerization dynamics of 4‐nitro‐4′‐dimethylaminoazobenzene (DA). In addition, the influence of the polarity and the relaxation behavior of the solvent on the mode‐specific vibrational and solvent reorganization energies was investigated. Raman spectra were recorded in solvents with different polarity parameters, n‐hexane and benzene, using 11 excitation wavelengths in the range 450–550 nm, scanning every 10 nm using the tunable laser pulse output of an optical parametric oscillator. It was observed that the solvent polarity plays a major role in influencing the excited‐state potential energy surfaces of DA. The plot of resonance Raman intensities versus excitation wavelength (Raman excitation profiles) of the Franck–Condon‐active fundamentals of DA shows that in n‐hexane, the locally excited state is more favorable than that in benzene where the charge‐transfer state is more stable. The distortions along the N N and C–N stretching vibrations of DA in n‐hexane and benzene infer isomerization via rotation in n‐hexane and inversion in benzene. The increase in solvent and vibrational reorganization energies with increasing solvent polarity parameter suggests greater distortion in the Franck–Condon excited state following photoexcitation. Copyright © 2001 John Wiley & Sons, Ltd.
Raman spectra of molecular crystals at high pressures: VII—Boron Triiodide
Authors: Anderson A. , Lettress Lauren 
Published: August 2002

AbstractRaman spectra of solid boron triiodide, BI3, at ambient temperature and at pressures up to 5 GPa are reported. Because of drastic but reversible colour changes to the samples and subsequent absorption, measurements at higher pressures were not possible. Four fundamental peaks, assigned as translational, librational, bending and stretching modes, were tracked as a function of pressure. The spectra evolve smoothly and there is no evidence of any structural phase transitions or major molecular distortions in this pressure range. All modes show increases in wavenumber with pressure, with that for the two lattice modes being most pronounced. The initially ‘soft’ crystal at ambient pressure stiffens appreciably, with an approximately fourfold increase in intermolecular bonding at 5 GPa. Copyright © 2002 John Wiley & Sons, Ltd.
The prognostic significance of preoperative serum CA 19‐9 in patients with resectable gastric carcinoma: comparison with CEA
Authors: Duraker Nüvi̇t , Çeli̇k Ali̇ Naci̇ 
Published: August 2002

AbstractBackground and ObjectivesIn this study, the prognostic value of pre‐operative serum levels of tumor markers CA 19‐9 and carcinoembryonic antigen (CEA) in gastric carcinoma which has been a controversial matter was investigated.MethodsPreoperative serum CA 19‐9 (cut‐off value 37 U/ml) and CEA (cut‐off value 5 ng/ml) levels were measured in 168 patients with resectable gastric carcinoma. The correlation between tumor marker levels and clinicopathological features and overall survival was studied.ResultsCA 19‐9 and CEA positivity rates were 31.5 and 17.8% respectively. In CA 19‐9 positive patients, the ratio of males, tumors exceeding subserosa and advanced stage tumors (stages III and IV) was significantly higher (P = 0.052, P = 0.0005 and P= 0.029, respectively). A weak correlation was found with CA 19‐9 positivity and tumor location; however, no correlation existed between CA 19‐9 positivity and age, tumor size, histologic type, lymph node, hepatic and peritoneal metastasis. The proportion of tumors extending beyond subserosa and with lymph node metastasis was significantly higher in CEA positive patients (P = 0.011 and P = 0.045, respectively). No correlation was found between CEA positivity and gender, age, tumor location, tumor size, and hepatic and peritoneal metastasis; however, a weak correlation existed between CEA positivity and histologic type and tumor stage. Overall survival was significantly poorer in CA 19‐9 and CEA positive patients (log‐rank test, P = 0.014, P = 0.003, respectively). However, the Cox proportional hazards regression analysis did not show independent prognostic value for both tumor markers.ConclusionsIn resectable gastric carcinoma, preoperative serum CA 19‐9 and CEA levels may indicate stage of the disease, but neither has an independent prognostic value. J. Surg. Oncol. 2001;76:266–271. © 2001 Wiley‐Liss, Inc.
Scottish visitor attractions: a collaborative future?
Authors: Fyall Alan , Leask Anna , Garrod Brian 
Published: August 2002

AbstractAlthough interorganisational collaboration is increasingly being accepted as a necessary, even desirable strategy for the tourism industry as a whole, there would appear to be a number of impediments to the implementation of collaborative initiatives among operators of visitor attractions. This paper focuses on the visitor attractions sector in Scotland, where such impediments are considered to be particularly serious. For a number of reasons, however, collaboration may represent a crucial strategy for visitor attractions in Scotland as they enter the new millennium. This paper sets out to assess the potential for intrasectoral, interorganisational collaborative strategies in enhancing the long‐term viability of the Scottish visitor attractions sector. Copyright © 2001 John Wiley & Sons, Ltd.
Tourism occupations and education: an exploration study
Authors: Churchward Jennifer , Riley Michael 
Published: August 2002

AbstractThis article contributes to the literature on the relationship between the tourism industry and vocational tourism education. It reports on an exploratory study of the work of a sample of tourism professionals and their education. The study attempts to classify tourism occupations by modifying an established scheme used in general administration. The study sought to find commonality within the diverse occupations and to go on to relate that to tourism education. The study found that the majority of the sample of 153 contained a common set of 24 activities. In educational terms, marketing, recreation and leisure and finance dominated as relevant subjects to study for tourism occupations. Copyright © 2002 John Wiley & Sons, Ltd.