bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding of recombinant PrPc to human plasminogen: Kinetic and thermodynamic study using a resonant mirror biosensor
Authors: Cuccioloni Massimiliano , Amici Manila , Eleuteri Anna Maria , Biagetti Massimo , Barocci Simone , Angeletti Mauro 
Published: December 2004

AbstractTransmissible spongiform encephalopathies are a class of sporadic, genetic and transmissible neurodegenerative diseases that affect both humans and animals. Propagation of these diseases is thought to be due to the misfolding of a neuronal glyco‐protein, PrPc, into a pathological insoluble conformer, PrPSc. In earlier works, some serum components were identified as exclusive PrPSc‐interacting proteins (Fisher et al., Nature 2000;408:479), and thus those macromolecules were thought to represent a potential diagnostic endogenous factor discriminating between normal and pathological prion proteins. In contrast, in agreement with a recent work (Kornblatt et al., Biochem Biophys Res Commun 2003;305:518), in this paper we present a detailed thermodynamic and kinetic characterization of the interaction between recombinant bovine PrPc 25–242 and the human serum component plasminogen, measured using a resonant mirror technique: our results reveal a high‐affinity interaction between the two binding partners. For comparison, the complex obtained from the purified full‐length PrPc and human plasminogen was also studied: both prion proteins (the recombinant bovine PrPc 25–242 and the purified full‐length PrPc) are able to bind human plasminogen. Both kinetic and thermodynamic parameters are affected by the modulation exerted by the H+ ions in solution. Moreover, the analysis of binding, according to canonical linkage relationships, suggests the involvement of a His residue, consistent with the interaction between other serine (pro)enzymes and their ligands. Proteins 2005. © 2004 Wiley‐Liss, Inc.
The effect of piperonyl butoxide on pyrethroid‐resistance‐associated esterases in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)
Authors: Young Susan J , Gunning Robin V , Moores Graham D 
Published: December 2004

AbstractPyrethroid resistance in field populations of Australian Helicoverpa armigera (Hübner) is primarily a consequence of the overproduction of esterase isoenzymes which metabolise and sequester pyrethroid insecticides. Biochemical studies have shown that pyrethroid‐resistance‐associated esterases in H armigera are inhibited by the insecticide synergist piperonyl butoxide (PBO). Esterase inhibition by PBO did not occur immediately after dosing, but exhibited maximum inhibition 3–4 h after dosage. Esterase activity subsequently recovered until full activity was restored by 24 h. Topical bioassays using a pre‐treatment of PBO showed that maximum H armigera mortality was achieved with pre‐treatment times corresponding to maximum esterase inhibition. These results demonstrated that, with correct temporal application, PBO can restore pyrethroid efficacy against H armigera. It would also be expected that restoration of efficacy with other conventional insecticides, currently compromised by esterase‐based resistance mechanisms, would occur. Copyright © 2005 Society of Chemical Industry
Mass spectrometric decompositions of copper complexes with esters and amides of nicotinic acid
Authors: Borowiak‐Resterna Aleksandra , Frański Rafał , Klonowska Karolina , Olszanowski Andrzej 
Published: December 2004

AbstractMass spectrometric decompositions of complexes of nicotinic acid esters and amides with copper are discussed. Liquid secondary ion mass spectrometry (LSIMS) was used as an ionisation technique and metastable ion spectra were recorded by using B/E linked scans. The fragmentation pathways consist mainly of the loss of one ligand molecule and also the cleavage of amide or ester bonds. It may be possible, on the basis of cleaved neutral fragments, to determine the site of coordination in the gas phase. It was also found that the presence of a chlorine atom affects the fragmentation pathways of complexes. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of N9/N7‐isomer ratio of alkyl (guaninyl)acetates by electrospray ionization tandem mass spectrometry
Authors: Ferenc Györgyi , Kele Zoltán , Kovács Lajos 
Published: December 2004

AbstractN9‐ and N7‐Substituted (guaninyl)acetic esters were studied by electrospray ionization tandem mass spectrometry (ESI‐MS/MS) in order to determine their ratio in alkylation reactions. The loss of ammonia is significantly different for the N9‐ and N7‐alkylated guanine regioisomer pairs. More importantly, the abundance of the [MH–17]+ ion is in linear correlation with the N9‐isomer content. Therefore, the ratio of regioisomers can be determined in a mixture containing these compounds. Copyright © 2004 John Wiley & Sons, Ltd.
A novel liquid chromatography/tandem mass spectrometry based depletion method for measuring red blood cell partitioning of pharmaceutical compounds in drug discovery
Authors: Yu Shaoxia , Li Shelly , Yang Hua , Lee Frank , Wu Jing‐Tao , Qian Mark G. 
Published: December 2004

AbstractA novel liquid chromatography/tandem mass spectrometry (LC/MS/MS)‐based depletion method for measuring compound partitioning between human plasma and red blood cells (RBC) in a drug discovery environment is presented. Conventionally, RBC partitioning is determined by separate measurements of drug concentrations in equilibrating plasma and whole blood or RBC using separate standards prepared in their respective matrices, i.e., in plasma and whole blood or RBC lysates. The process is very tedious, labor‐intensive, and difficult to automate. In addition, interferences from the heme and other highly abundant cellular composites make the measurement of the drug concentration in whole blood or RBC inevitably variable even with a highly specific LC/MS/MS method. Therefore, there is an imminent need to develop a straightforward and fast method to assess the partitioning of drug‐like compounds in RBC.This work describes an LC/MS/MS‐based depletion assay that measures the compound concentration in plasma that has been equilibrating with RBC. Compounds were spiked into fresh human whole blood and plasma respectively to a final concentration of 500 nM. Both the spiked whole blood and plasma control were incubated at 37°C for up to 60 min. During the time course, aliquots of plasma and whole blood from both incubation mixtures were sampled at 10 and 60 min. The whole blood samples were centrifuged to yield the plasma. The plasma samples from both incubations were extracted using a protein precipitation method, and analyzed using LC/MS/MS under the multiple‐reaction monitoring (MRM) mode. The RBC partitioning ratio was calculated using the analyte peak area responses of the plasma samples through an equation deduced in this work.The method was first tested using two commercial compounds, phenoprobamate and acetazolamide, to determine the optimal incubation conditions and the concentration dependency of the assay. The assay reproducibility was also assessed by three inter‐day assays for phenoprobamate. This method was further evaluated using 20 commercial compounds of different classes with a wide range of RBC partitioning coefficients and the results were compared with those reported in the literature. Excellent correlation (R2 = 0.9396) was found between the measured and literature values. In addition, several proprietary compounds were assayed using both the new and traditional methods and the measured partitioning ratios from the two methods are equivalent. The experiments in this work demonstrate that the LC/MS/MS‐based depletion method can provide direct and accurate measurement of RBC partitioning for compounds in drug discovery. Copyright © 2004 John Wiley & Sons, Ltd.
Natural water specimen preparation for TXRF analysis using a Johansson wavelength‐dispersive spectrometer
Authors: Kurunczi S. , Sakurai K. 
Published: December 2004

AbstractA special method of specimen preparation is described aimed at achieving a small size of the order of 50 µm. The difficulty is especially great when preparing droplet residues from natural water on a silicon wafer as a supporting material for this experiment. We report the first promising results using an HF etching method to obtain a hydrophobic silicon surface. A specimen (residue) size of ∼ 80 µm was obtained on the modified silicon surface, making wavelength‐dispersive total reflection x‐ray fluorescence (WD‐TXRF) analysis possible for a standard reference sample of natural water (TMDA 53.2). Copyright © 2004 John Wiley & Sons, Ltd.
X‐ray fluorescence analysis applied to geochemistry of quartz in Argentina
Authors: Pérez D. , Rubio M. , Bonalumi A. , Sfragulla J. , López A. , Guereschi A. , Vázquez C. , Gozalvez M. , Luchesi M. , Badini R. G. , Cuffini S. L. , Sphan G. , Inga M. , Germanier A. , Servant R. E. 
Published: December 2004

AbstractThe growing demand for high‐purity quartz in the international market led to the systematic investigation of the geochemical quality of this mineral in deposits Argentina. This study is a contribution to the scarce information on the geochemistry of quartz in Argentina. A total of 525 multielemental chemical analyses were performed with XRF spectrometry in less than 3 months. SiO2 concentration was calculated by difference from XRF impurity determinations. As a result of this study, 36 sites over 141 sampled deposits were identified as being of desirable quality. Low‐Z oxides, considered critical impurities for quartz, were determined by atomic absorption spectrometry, only in samples of these selected sites, because of high XRF detection limits. The analytical results allowed the classification of the quality of quartz according to its environment and geological genesis. It could be determined that better purity quartz corresponds to veins far away from the Achala and Alpa Corral batholith and occurs in metamorphic rocks, followed by pegmatitic quartz from inside the batholith and lastly by quartz of well‐known hydrothermal origin. Copyright © 2004 John Wiley & Sons, Ltd.
Electron shake process following inner‐shell ionization
Authors: Mukoyama Takeshi 
Published: December 2004

AbstractElectron shakeup and shakeoff probabilities accompanying inner‐shell ionization of atoms were calculated for K‐, L‐ and M‐shell electrons using hydrogenic wavefunctions. The dependence of shake probabilities on atomic number Z is estimated. It is found that both shakeoff and shakeup probabilities are proportional to 1/Z2. Based on this Z‐dependence, the shakeup‐plus‐shakeoff probabilities are expressed in a simple analytical form with two parameters. Copyright © 2004 John Wiley & Sons, Ltd.
Energy‐dispersive XRF spectrometer for Ti determination (TITAN)
Authors: Cheburkin A. K. , Shotyk W. 
Published: December 2004

AbstractAn energy‐dispersive XRF analyser was designed and constructed for determining Ti in plant and peat materials at low (ppm) concentrations. The XRF analyzer for Ti analysis (TITAN) uses monochromatic excitation obtained from a crystal diffraction monochromator and Co target x‐ray diffraction tube. In addition to precise and sensitive analyses of Ti, other minor elements (Ca, K, Cl, S, P, Ba) in powdered plant and peat samples can be measured with only a minimum of sample preparation (drying, milling). The limits of detection obtained are K 2.5, Ca 1.5, Ti 0.9, Cr 0.7 and Mn 0.5 ppm using a 600 s acquisition time. The instrument was used to determine Ti concentrations in pre‐anthropogenic peat samples up to 9000 years old. Copyright © 2004 John Wiley & Sons, Ltd.
A High Pressure Study on NH4Pb2Br5 Type Compounds Part II: Electronic Structure and Changes under High Pressure
Authors: Becker Daniel , Beck Horst P. 
Published: December 2004

AbstractIn this work, we present a theoretical study (based on DFT‐calculations) of the electronic properties of compounds crystallising in a NH4Pb2Br5 type structure in a wide pressure range. The main focus of this study is to elucidate the nature of bonding of the ns2‐cations at ambient and elevated pressure.For a better understanding of the structure and bonding, the DOS of these compounds are evaluated and discussed on the basis of a simple model assuming mainly ionic interactions. The calculations are complemented by an orbital analysis using the crystal orbital Hamilton population (COHP) and an analysis of the electronic density topology with the electron localisation function (ELF). Structural and theoretical investigations give results that are in excellent agreement: The DFT‐calculations confirm the existence of bonding interactions between the ns2‐cations at elevated pressure.Our study indicates that the “character” of the additional electron pair changes with increasing pressure from nonbonding to bonding in agreement with a simple model system of two interacting ns2‐cations.
Crystal Structure Investigations on Imines derived from 3‐Ferrocenyl‐prop‐2‐enal Crystallizing in Non‐centrosymmetric Space Groups
Authors: Imhof Wolfgang 
Published: December 2004

AbstractThe condensation of 3‐ferrocenyl‐prop‐2‐enal with primary amines leads to the formation of the corresponding imines in good yields. The crystal structures of imines derived from p‐dimethylamino‐aniline and furfurylamine are determined by the ability of the functional groups to act as hydrogen bond donor or acceptor sites. Although N, N‐dimethyl‐N′‐(3‐ferrocenyl‐allylidene)‐benzene‐1, 4‐diamine and furan‐2‐ylmethyl‐(3‐ferrocenyl‐allylidene)‐amine are achiral molecules they crystallize in the non‐centrosymmetric space groups P21 and Pca21, respectively. The molecular architecture of N, N‐dimethyl‐N′‐(3‐ferrocenyl‐allylidene)‐benzene‐1, 4‐diamine is realized by the incorporation of dichloromethane acting as hydrogen bond donor and acceptor with both hydrogen and both chlorine atoms. On the other hand, the molecules of furan‐2‐ylmethyl‐(3‐ferrocenyl‐allylidene)‐amine are linked by hydrogen bonds towards the centroid of one of the cyclopentadienyl ligands and towards the oxygen atom of the furan ring to produce infinite chains.
Halfsandwich Complexes Containing the Tetrathiotungstate Chelate Ligand. Crystal and Molecular Structure of Cp*Rh(PMe3)[(μ‐S)2WS2] (Cp* = η5‐Pentamethylcyclopentadienyl)
Authors: Herberhold Max , Jin Guo‐Xin , Rheingold Arnold L. 
Published: December 2004

AbstractThe reactions of Cp*M(PMe3)Cl2 (M = Rh (1a), Ir (1b)) with (NEt4)2[WS4] led to the heterodimetallic sulfido‐bridged complexes Cp*M(PMe3)[(μ‐S)2WS2] (M = Rh (2a), Ir (2b)), whereas the dimers [Cp*MCl(μ‐Cl)]2 (M = Rh (4a), Ir (4b)) reacted with (NEt4)2[WS4) to give the known trinuclear compounds [Cp*M(Cl)]2(μ‐WS4) (M = Rh (5a), Ir (5b)). Hydrolysis of the terminal W=S bonds converts 2a, b into Cp*M(PMe3)[(μ‐S)2WO2] (M = Rh (3a), Ir (3b)). Salts of a heterodimetallic anion, A[CpMo(I)(NO)(WS4)] (6) (A+ = NEt4+, NPh4+) were obtained by reactions of [CpMo(NO)I2]2 with tetrathiotungstates, A2[WS4]. The complexes were characterized by IR and NMR (1H, 13C, 31P) spectroscopy, and the X‐ray crystallographic structure of Cp*Rh(PMe3)[(μ‐S)2WS2] (2a) has been determined. The bond lengths and angles in the coordinations spheres of Rh and W in 2a (Rh···W 288.5(1) pm) are compared with related complexes containing terminal [WS42—] chelate ligands.
The influence of folate serum levels on depressive mood and mental processing in patients with epilepsy treated with enzyme-inducing anti-epileptic drugs
Authors: Rösche J. , Uhlmann C. , Weber R. , Fröscher W. 
Published: December 2004

Background:Folate deficiency is common in patients with epilepsy and also occurs in patients with depression or cognitive deficits.Objective:This study investigates whether low serum folate levels may contribute to depressive mood and difficulties in mental processing in patients with epilepsy treated with anti-epileptic drugs inducing the cytochrome P450.Methods:We analysed the serum folate levels, the score in the Self Rating Depression Scale (SDS) and the results of a bedside test in mental processing in 54 patients with epilepsy.Results:There was a significant negative correlation between the serum folate levels and the score in SDS and significant positive correlations between the score in SDS and the time needed to process an interference task or a letter-reading task.Conclusions:Low serum folate levels may contribute to depressive mood and therefore to difficulties in mental processing. Further studies utilizing total plasma homocysteine as a sensitive measure of functional folate deficiency and more elaborate tests of mental processing are required to elucidate the impact of folate metabolism on depressive mood and cognitive function in patients with epilepsy.
Prevalence of insomnia in Poland — results of the National Health Interview Survey
Authors: Kiejna A. , Wojtyniak B. , Rymaszewska J. , Stokwiszewski J. 
Published: December 2004

Background:Sleep disturbances are one of the most common underdiagnosed and undertreated health problems among the adult population.Objectives:The aim of the study was to assess the prevalence of sleeping problems and their relation to sociodemographic characteristics in the Polish population, based on the results of the National Health Interview Survey carried out by the Central Statistical Office in 1996.Methods:A stratified sampling scheme, involving two steps, was used. Standardized prevalence ratios (SPRs and their 95% confidence intervals) were calculated. Assessment of sleep-related problems was based on six questions. A representative Polish sample (47 924 non-institutionalized, adult respondents) was interviewed.Results:Nearly one-fourth of Polish inhabitants suffered from insomnia. The percentage was significantly higher among women (28.1%) than among men (18.1%). The prevalence of insomnia increased with age and was highest in divorced respondents. Respondents of both sexes with higher educational levels suffered from insomnia less often than individuals with lower levels of education. The problem of insomnia applies in a similar degree to inhabitants of both rural and urban regions. About one-twentieth of inhabitants of Poland experienced recent sleep deterioration related to problems. It was associated positively with age, female gender and lower education. About 20% of the population get up not rested in the morning, women significantly more often than men, urban residents more often than rural ones.Conclusions:Sleep-related problems are common and the results are comparable with those from other countries. The findings have important implications, such as the necessity of better education of the public community about the identification and possibilities of treatment of sleep disturbance.
The effect of sevoflurane on glutamate release and uptake in rat cerebrocortical presynaptic terminals
Authors: Vinje M. L. , Moe M. C. , Valø E. T. , Berg‐Johnsen J. 
Published: December 2004

Background: Volatile anaesthetics exert their effect in the brain mainly by reducing synaptic excitability. Isoflurane abates excitation by reducing the release and increasing the uptake of transmitter glutamate into the presynaptic terminal. The exact molecular mechanisms exerting these effects, however, are not clear. Voltage‐gated calcium channels have been proposed as the pharmacological target. The present study examines the effect of sevoflurane on synaptic glutamate release and free cytosolic calcium and the effect on high‐ and low‐affinity uptake of L‐glutamate using isolated presynaptic terminals prepared from rat cerebral cortex.Methods: Released glutamate was measured fluorometrically in a spectrophotometer as the fluorescence of NADPH and calcium as the fluorescence of fura‐2. 4‐aminopyridine was used to induce membrane depolarization. Glutamate uptake was measured in a series of different concentrations of L‐glutamate corresponding to the high‐ and the low‐ affinity uptake systems adding a fixed concentration og radiolabelled glutamate. The labelling was measured by counting disintegrations per min in a β‐scintillation counter.Results: Sevoflurane reduced the calcium‐dependent glutamate release in a dose‐dependent manner as sevoflurane 1.5, 2.5 and 4.0% reduced the release by 58, 69 and 94%, respectively (P<0.05). Membrane depolarization induced an increase in free cytosolic calcium by 25%. Sevoflurane did not affect this increase. Neither the high‐ nor the low‐affinity uptake transporter systems are affected by the anaesthetic.Conclusion: These results indicate that different volatile anaesthetics may act differently on the presynaptic terminal. The exact modes of action have to be further investigated.
Childhood abuse as a risk factor for psychotic experiences
Authors: Janssen I. , Krabbendam L. , Bak M. , Hanssen M. , Vollebergh W. , de Graaf R. , van Os J. 
Published: December 2004

Objective: To examine the hypothesis that individuals from the general population who report childhood abuse are at increased risk of developing positive psychotic symptoms.Method: Data were derived from a general population sample of 4045 subjects aged 18–64 years. First ever onset of positive psychotic symptoms at 2‐year follow‐up were assessed using the Composite International Diagnostic Interview and additional clinical interviews if necessary. Childhood abuse was assessed at baseline.Results: Baseline reported childhood abuse predicted development of positive psychotic symptoms associated with need for care [odds ratio (OR) = 11.5, 95% CI 2.6–51.6]. This association remained after adjustment for demographic variables, reported risk factors and presence of any lifetime psychiatric diagnosis at baseline (OR = 7.3, 95% CI 1.1–49.0).Conclusion: The results suggest that early childhood trauma increases the risk for positive psychotic symptoms. This finding fits well with recent models that suggest that early adversities may lead to psychological and biological changes that increase psychosis vulnerability.
Determinants of quality of life in first‐episode psychosis
Authors: Malla A. K. , Norman R. M. G. , McLean T. S. , MacDonald C. , McIntosh E. , Dean‐Lashley F. , Lynch J. , Scholten D. , Ahmed R. 
Published: December 2004

Objective: To assess patient and/or illness characteristics associated with aspects of quality of life (QOL) in first‐episode psychosis (FEP).Method: Patient characteristics, symptom ratings and Wisconsin QOL scale (client version) were assessed. Data were analysed with correlation coefficients and a hierarchical regression analysis.Results: Patients presented with varying levels of QOL on different domains. The level of ‘general satisfaction’ was related to age of onset and social premorbid adjustment; ‘weighted index of QOL’ to social premorbid adjustment and inversely to educational premorbid adjustment; ‘social relations’ inversely to duration of untreated psychosis (DUP), length of prodrome and negative symptoms; ‘psychological well‐being’ inversely to depression and educational premorbid adjustment; ‘activities of daily living’ to social premorbid adjustment and inversely to negative symptoms; and ‘outlook on symptoms’ to level of depression.Conclusion: Domains of self‐rated QOL in FEP patients are differentially associated with malleable and non‐malleable aspects of patient and illness characteristics.