bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of thiols and glutathione conjugates of depsipeptide FK228 (FR901228), a novel histone protein deacetylase inhibitor, in the blood
Authors: Xiao Jim J. , Byrd John , Marcucci Guido , Grever Michael , Chan Kenneth K. 
Published: March 2003

AbstractFour glutathione (GSH) conjugates and two thiols were detected when depsipeptide FK228, formerly FR901228, a naturally occurring potent histone deacetylase (HDAC) inhibitor, was incubated in rat or human plasma in the presence of GSH. Their structures were elucidated by the high‐performance liquid chromatography/electrospray ionization multi‐stage mass spectrometry (HPLC/ESI‐MSn) technique, and in some cases confirmed by accurate mass measurement. These products were also detected in rat and human blood homogenates following their incubation with FK228, but were not detected in GSH solution alone. A possible scheme for its formation is proposed. One of the thiols has recently been found to be more active as a histone deacetylase inhibitor than the parent compound. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of 3‐chlorotyrosine as a specific marker of protein oxidation: the use of N(O,S)‐ethoxycarbonyltrifluoroethyl ester derivatives and gas chromatography/mass spectrometry
Authors: Pietzsch Jens , Kopprasch Steffi , Bergmann Ralf 
Published: March 2003

AbstractN(O,S)‐Ethoxycarbonyltrifluoroethyl amino acid esters are formed by the reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. The use of these derivatives for a rapid and sensitive determination of 3‐chlorotyrosine, a highly specific marker of myeloperoxidase‐catalyzed protein oxidation, by using standard gas chromatography/electron impact mass spectrometry, is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison between electrochemistry/mass spectrometry and cytochrome P450 catalyzed oxidation reactions
Authors: Jurva Ulrik , Wikström Håkan V. , Weidolf Lars , Bruins Andries P. 
Published: March 2003

AbstractThe extent to which electrochemistry on‐line with electrospray mass spectrometry can be used to mimic cytochrome P450 catalyzed oxidations has been investigated. Comparisons on the mechanistic level have been made for most reactions in an effort to explain why certain reactions can, and some cannot, be mimicked by electrochemical oxidations. The EC/MS/MS system used successfully mimics in cases where the P450 catalyzed reactions are supposed to proceed via a mechanism initiated by a one‐electron oxidation, such as N‐dealkylation, S‐oxidation, P‐oxidation, alcohol oxidation and dehydrogenation. The P450 catalyzed reactions initiated via direct hydrogen atom abstraction, such as O‐dealkylation and hydroxylation of unsubstituted aromatic rings, generally had a too high oxidation potential to be electrochemically oxidized below the oxidation potential limit of water, and were not mimicked by the EC/MS/MS system. Even though the EC/MS/MS system is not able to mimic all oxidations performed by cytochrome P450, valuable information can be obtained concerning the sensitivity of the substrate towards oxidation and in which position of the molecule oxidations are likely to take place. For small‐scale electrochemical synthesis of metabolites, starting from the drug, the EC/MS/MS system should be very useful for quick optimization of the electrochemical conditions. The simplicity of the system, and the ease and speed with which it can be applied to a large number of compounds, make it a useful tool in drug metabolism research. Copyright © 2003 John Wiley & Sons, Ltd.
Method development for the concentration determination of a protein in human plasma utilizing 96‐well solid‐phase extraction and liquid chromatography/tandem mass spectrometric detection
Authors: Ji Qin C. , Gage Eric M. , Rodila Ramona , Chang Min S. , El‐Shourbagy Tawakol A. 
Published: March 2003

AbstractAlthough liquid chromatography/tandem mass spectrometry (LC/MS/MS) technology has been widely used for quantitative analysis of small organic molecules, it has been a challenging task to quantitatively analyze protein samples utilizing this technology in biological matrices for pre‐clinical and clinical studies. Here we present our initial results in method development for the quantitative determination of rK5 protein concentrations in human plasma samples utilizing LC/MS/MS technology. A protein similar in structure to rK5, but with a slightly reduced molecular weight, was used as internal standard. A 96‐well solid‐phase extraction procedure was developed to effectively extract protein analytes from plasma samples. Quantitative analysis was obtained by a novel approach of protein monitoring that employed selective reaction monitoring (SRM). Even though mass spectrometry of the internal standard protein gave no fragment ions, SRM monitoring greatly reduced background interference. Using samples prepared in human plasma with sodium EDTA as anticoagulant, a correlation coefficient (r2) of 0.9940 was obtained by producing a single standard curve with the injection of six rows of standards with a concentration range from 100 ng/mL to 10 μg/mL. The mean analytical recovery for these standards ranged from 91.5 to 103.6%. The CVs for individual standard levels ranged from 3.7 to 20.9%. The experiment was also repeated using samples prepared in human plasma with sodium heparin as anticoagulant, which produced a correlation coefficient (r2) of 0.9952 obtained from a single standard curve with the injection of four rows of standards with a concentration range from 50 ng/mL to 10 μg/mL. The mean analytical recovery for the standards ranged from 96.2 to 104.6%. The CVs for individual standard levels ranged from 2.6 to 15.6%. Copyright © 2003 John Wiley & Sons, Ltd.
Monitoring the synthetic reaction of a polyamide/peptide conjugate using electrospray ionization mass spectrometry
Authors: Zhu Changjin , Yang Xiaoli , Cao Shuxia , Liu Yan , Yuan Gu , Liu Dan , Zhao Yufen 
Published: March 2003

AbstractRecently, the chemical structures of a series of monoimidazole/polyamine conjugates were studied in this laboratory using electrospray ionization mass spectrometry (ESI‐MS) combined with tandem mass spectrometry (ESI‐MS/MS). The method was found to be a powerful tool for the identification of this class of compounds. During the synthesis of targeted polyamide/peptide conjugates as derivatives or analogues of netropsin and distamycin, the method was applied to analyze and track the coupling reaction for the formation of the polyamide, which was difficult to achieve using thin layer chromatography (TLC). Characteristic fragmentation pathways for a nitro‐monoimidazole conjugate, an amino‐monoimidazole conjugate, and the final product (a nitro‐diimidazole conjugate) were explored. The fragmentations of these conjugates were strongly affected by the presence of an amino group instead of a nitro group in the molecule, and led to the identification of the three compounds in the reacting solution or in the final reaction mixture. Consequently, the reaction could be monitored successfully and the synthetic route optimized. Copyright © 2003 John Wiley & Sons, Ltd.
Amide bond cleavage in deprotonated tripeptides: a newly discovered pathway to ″b2 ions
Authors: Harrison Alex G. , Michael Siu K. W. , El Aribi Houssain 
Published: March 2003

AbstractThe fragmentation reactions of the [MH]− ions of the tripeptides H‐Gly‐Leu‐Sar‐OH, H‐Leu‐Gly‐Pro‐OH and H‐Gly‐Leu‐Gly‐OH have been investigated in detail using energy‐resolved mass spectrometry, isotopic labelling and MS3 experiments. It is shown that the major route to the ″b2 ions involves loss of a neutral amine from the a3 ([MHCO2]−) ion rather than being formed directly by fragmentation of the [MH]− ion. When there is no C‐terminal amidic hydrogen (Sar, Pro), loss of a neutral amine is the dominant primary fragmentation reaction of the a3 ion. However, when there is a C‐terminal amidic hydrogen (Gly), elimination of the N‐terminal amino acid residue is the major fragmentation reaction of the a3 ion and formation of the ″b2 ion is greatly reduced in importance. It is proposed that the ″b2 ions are deprotonated oxazolones. Copyright © 2003 John Wiley & Sons, Ltd.
An atmospheric pressure matrix‐assisted laser desorption/ionization ion trap with enhanced sensitivity
Authors: Miller Christine A. , Yi Donghui , Perkins Patrick D. 
Published: March 2003

AbstractWhen atmospheric pressure matrix‐assisted laser desorption/ionization (AP‐MALDI) became commercially available, the technique generated a great deal of interest because ion production was decoupled from mass analysis. Mass accuracy and resolution were therefore dependent on parameters governing the mass analyzer rather than the matrix and sample preparation. Researchers have successfully used AP‐MALDI sources with both orthogonal acceleration time‐of‐flight (oaTOFMS) and ion trap mass spectrometers. However, one limitation of the technique has been sensitivity, especially for mixtures of peptides generated from tryptic digests. In this work, data are presented documenting an increase in sensitivity of approximately two orders of magnitude as compared with results previously reported in the literature. The improvement in sensitivity is thought to derive primarily from the novel use of a countercurrent heated gas stream directed at the sample, although the target plate position and ion sampling configuration have also been optimized to reduce chemical noise from low molecular weight ions. A tryptic digest of BSA containing 125 attomoles on the plate was successfully identified in MS‐only mode, while MS/MS analysis of 250 attomoles of the same digest provided product ion spectra with sufficient information to identify the protein. More complicated mixtures of standard proteins were used to model proteomics experiments, and preliminary data suggest a minimum working dynamic range of 20‐fold for the analysis of mixtures of protein digests. Copyright © 2003 John Wiley & Sons, Ltd.
Surface and interface characterization of polyester‐based polyurethane/nano‐silica composites
Authors: Chen Xichong , You Bo , Zhou Shuxue , Wu Limin 
Published: March 2003

AbstractPolyester‐based polyurethane/nanosilica composites were prepared via in situ polymerization and investigated by contact angle measurement, transmission electron microscopy (TEM), atomic force microscopy (AFM) and peel testing in an Instron testing machine. The contact angle and surface free energy results show that nanosilica tended to enrich at the interface between nanocomposite polymers and the substrates, TEM indicated that nanosilica particles were evenly dispersed in the bulk and AFM demonstrated that nanoparticles were located at both the surfaces and interfaces of nanocomposite polymers and that the roughness of both the surfaces and interfaces had a decreasing tendency as the nanosilica content increased, as did the adhesion strength between the nanocomposite polymers and substrates. Copyright © 2003 John Wiley & Sons, Ltd.
Novel floating‐type low‐energy ion gun for high‐resolution depth profiling in ultrahigh vacuum
Authors: Mizuhara Y. , Kato J. , Nagatomi T. , Takai Y. , Aoyama T. , Yoshimoto A. , Inoue M. , Shimizu R. 
Published: March 2003

AbstractA floating‐type low‐energy ion gun (FLIG) has been developed for high‐resolution depth profiling in ultrahigh vacuum (UHV). This UHV‐FLIG allows Ar+ ions of primary energy down to 50 eV to be provided with high current intensity. The developed UHV‐FLIG was sufficiently compact, being ∼30 cm long, to be attached to a commercial surface analytical instrument. The performance of the UHV‐FLIG was measured by attaching it to a scanning Auger electron microprobe (JAMP‐10, Jeol), the base pressure of which in the analysis chamber was ∼1 × 10−7 Pa. The vacuum condition of ∼5 × 10−6 Pa was maintained during operation of the UHV‐FLIG without a differential pumping facility. Current density ranged from 41 to 138 µA cm−2 for Ar+ ions of primary energy 100–500 eV at the working distance of 50 mm. This ensures a sputtering rate of ∼10 nm h−1 with 100 eV Ar+ ions for Si, leading to depth profiling of high resolution in practical use. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitative chemical composition of thin films with infrared spectroscopic ellipsometry: application to hydrated oxide films on aluminium
Authors: Van Gils S. , Melendres C. A. , Terryn H. 
Published: March 2003

AbstractA method to quantify the composition of thin films using infrared spectroscopic ellipsometry (IRSE), supplemented by visible spectroscopic ellipsometry (VISSE), is proposed. Because ellipsometry measures the thickness and optical constants of a surface layer simultaneously, the absorption coefficient of the film as a function of wavelength can be obtained. Using values of the absorption coefficients for the pure components of the film, the percentages (mol.% or wt.%) of each component in the film can be calculated. The method is demonstrated in a study of the hydration of oxide films on electropolished aluminium and the anodically formed barrier oxide film. The IRSE technique shows that hydration of the films by immersion in boiling water results in the conversion of aluminium oxide to pseudoboehmite. Copyright © 2003 John Wiley & Sons, Ltd.
Radiation‐induced migration of additives in PVC‐based biomedical disposable devices. Part 1. Surface morphology by AFM and SEM/XEDS
Authors: Manfredini M. , Marchetti A. , Atzei D. , Elsener B. , Malagoli M. , Galavotti F. , Rossi A. 
Published: March 2003

AbstractTwo different types of plasticized poly(vinyl chloride) (PVC) used for biomedical disposable devices—extruded and injection moulded—were studied in the non‐sterilized condition and after 25 and 50 kGy of beta irradiation. The polymer surfaces were analysed by scanning electron microscopy (SEM) equipped with an x‐ray energy‐dispersive spectroscopy (XEDS) and by atomic force microscopy (AFM). The inner surface of two parts of a venous line showed a different morphology according to their original formulation (for extrusion or injection moulding process) and reacted differently on sterilization with beta irradiation. Moulded parts were affected only slightly by the radiation step, whereas the variations were bigger for the extruded parts. In order to gain the best performances for the medical devices studied, the utmost care must be taken in the sterilization step, which should be optimized as well as the other steps of the manufacturing process. Copyright © 2003 John Wiley & Sons, Ltd.
Family Homelessness: State or Trait?
Authors: Shinn Marybeth 
Published: March 2003

AbstractCompares conceptualizations of homelessness as a temporary state through which people pass or a permanent trait that emanates from individual characteristics. Evidence from a longitudinal study of 564 homeless families in New York City and additional secondary sources supports the view that for families, homelessness is a temporary state that is resolved by the provision of subsidized housing. Even for single individuals with severe mental disturbances, housing is a key factor in ending homelessness, although here there is more evidence that social services also contribute. Policy implications are that governments should take a more active role in reducing homelessness by providing access to subsidized housing.
Giving and Receiving Help: Interpersonal Transactions in Mutual‐Help Meetings and Psychosocial Adjustment of Members
Authors: Roberts Linda J. , Salem Deborah , Rappaport Julian , Toro Paul A. , Luke Douglas A. , Seidman Edward 
Published: March 2003

AbstractThe helping transactions that occur in group meetings have been theorized to be important therapeutic mechanisms within mutual‐help (or self‐help) groups. Hypothesized links between giving and receiving help and psychosocial adjustment were examined in a mutual‐help group for individuals with serious mental illness (GROW). Participants' adjustment was assessed at two time points and helping behaviors were measured with observational coding of weekly group interactions during the period between assessments. Frequencies of helping behaviors were used to predict Time 2 adjustment after controlling for initial adjustment. Consistent with the helper therapy principle, giving help to others predicted improvements in psychosocial adjustment; giving advice was a unique predictor. Total amount of help received was not associated with adjustment, but receiving help that provided cognitive reframing was associated with better social adjustment. A predicted interaction suggested that receiving help was related to better functioning when members experienced high levels of group integration.
If It's Offered, Will They Come? Influences on Parents' Participation in a Community‐Based Conduct Problems Prevention Program
Authors: Orrell-Valente Joan K. , Pinderhughes Ellen E. , Valente Ernest , Laird Robert D. , Bierman Karen L. , Coie John D. , Dodge Kenneth A. , Greenberg Mark T. , Lochman John E. , McMahon Robert J. , Pinderhughes Ellen E. 
Published: March 2003

AbstractThis study examined influences on the rate and quality of parent participation in the Fast Track Program, a multi‐system, longitudinal preventive intervention for children who are at risk for conduct problems. A theoretical model of the relations among family coordinator characteristics, parent characteristics, the therapeutic engagement between family coordinator and parent, and rate and quality of parent participation was the basis for this study. “Family coordinators” are the Fast Track program personnel who conduct group‐based parent‐training sessions and home visits. Participants in this study included 12 family coordinators (42% were African American, 58% European American) and 87parents (55% were African American, 45% European American). The level of therapeutic engagement between the parent and the family coordinator was positively associated with the rate of parent attendance at group training sessions. The extent of family coordinator‐parent racial and socioeconomic similarity and the extent of the family coordinator's relevant life experiences were highly associated with the level of therapeutic engagement. The quality, but not the rate, of participation was lower for African American parents. Implications of these findings for preventive intervention with this population are discussed.
Volunteer Participation in Context: Motivations and Political Efficacy Within Three AIDS Organizations
Authors: Stewart Eric , Weinstein Rhona S. 
Published: March 2003

AbstractEmployed quantitative and qualitative data in a contextual examination of participation in three San Francisco‐area HIV/AIDS organizations: an urban, gay community‐based social change setting; an urban, broadly focused information/referral setting; and a suburban individual support setting. The settings attracted different kinds of volunteers and engaged them differently with the setting, each other, and community. In quantitative analyses external political efficacy (belief in the responsiveness of sociopolitical systems to change efforts) significantly distinguished settings, but was best predicted by setting‐moderated relationships to scaled motivations. Qualitative data more clearly illuminated volunteers' motivations for participation, as well as complex, embedded relationships between setting, motivations, attitudes about sociopolitical participation, and personal and community experience and identification. Together the findings underscore three unique but related stories for the three AIDS organizations, and the value of contextual approaches to participation and empowerment.
Ethnicity and Social Support During Pregnancy
Authors: Sagrestano Lynda M. , Feldman Pamela , Rini Christine Killingsworth , Woo Grace , Dunkel-Schetter Christine 
Published: March 2003

AbstractData from two multi‐ethnic prospective studies of African American, Latina, and non‐Hispanic White pregnant women were used to examine the influence of contextual factors on social support processes during pregnancy. Multiple types of support (perceived support, received support, support satisfaction, network support) and sources of support (baby's father, family, friends) were assessed. The role of ethnicity in social support was examined after controlling for the contribution of related contextual factors (SES, marital status, age, parity, employment) to these processes. The impact of ethnicity and related contextual factors differed across sources of social support. Ethnic differences in support from family and friends, but not from the baby's father, emerged. However, marital status was a consistent predictor of support from the baby's father, and SES was a consistent predictor of support from friends. Overall, the findings of two studies suggest that although ethnicity is associated with support from friends and family, other contextual factors, such as marital status and SES, influence support processes during pregnancy.
Substance Use and Psychological Adjustment in Homeless Adolescents: A Test of Three Models
Authors: MacLean Michael G. , Paradise Matthew J. , Cauce Ana Mari 
Published: March 2003

AbstractThree models of adolescent substance use, the deviance‐prone, affect‐regulation, and normative development models, were assessed regarding their ability to predict the substance use of a high‐risk homeless adolescent sample with high rates of deviance, depression, and substance use. Hierarchical multiple regression analyses that included tests for curvilinear and gender interaction effects were performed. Results supported the deviance‐prone model most strongly, with delinquency but not aggressive behavior predicting substance use. The affect‐regulation model received support for females but not for males. With respect to the normative development model, results did not indicate that moderate substance users were better off than abstainers in terms of negative affect or interpersonal relationships.
Fertile Ground for Community: Inner‐City Neighborhood Common Spaces
Authors: Kuo Frances E. , Sullivan William C. , Coley Rebekah Levine , Brunson Liesette 
Published: March 2003

AbstractResearch suggests that the formation of neighborhood social ties (NSTs) may substantially depend on the informal social contact which occurs in neighborhood common spaces, and that in inner‐city neighborhoods where common spaces are often barren no‐man's lands, the presence of trees and grass supports common space use and informal social contact among neighbors. We found that for 145 urban public housing residents randomly assigned to 18 architecturally identical buildings, levels of vegetation in common spaces predict both use of common spaces and NSTs; further, use of common spaces mediated the relationship between vegetation and NSTS. In addition, vegetation and NSTs were significantly related to residents' senses of safety and adjustment. These findings suggest that the use and characteristics of common spaces may play a vital role in the natural growth of community, and that improving common spaces may be an especially productive focus for community organizing efforts in inner‐city neighborhoods.