bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kidney uptake of 186/188Re(V)‐DMSA is significantly reduced when the reducing agent is changed from stannous ion to metabisulfite
Authors: Kothari Kanchan , Satpati Drishty , Mukherjee Archana , Sarma H. D. , Venkatesh Meera , Pillai M. R. A. 
Published: September 2002

AbstractWe describe the work carried out on the preparation of 186/188Re(V)‐DMSA, which showed lower kidney retention, formulated by using metabisulfite as the reducing agent. The complex was prepared by reducing 186/188ReO4− (100 μg, 0.54 μM, ∼150 MBq) in the presence of Na2S2O5 (30 mg, 0.15 mM) and reacting with DMSA (10 mg, 0.05 mM) in saline at pH 3.5 and at 80°C for 1 h. The complex was characterized by TLC using acetone and saline as two different solvent systems. Reverse phase HPLC carried out using isocratic system with 90:10 water/acetonitrile mobile phase showed the existence of four species. Biodistribution studies were carried out in albino mice with 186/188Re(V)‐DMSA prepared via metabisulfite reductant [186/188Re(V)‐DMSA (MBS)] as well as stannous chloride reductant [186/188Re(V)‐DMSA (SnCl2)]. The distribution patterns were similar except for kidney uptake. Kidney retention in case of 186/188Re(V)‐DMSA (MBS) was lower [0.68 (±0.06)%/g] than that observed in case of 186/188Re(V)‐DMSA (SnCl2) [2.93(±0.93)%/g] after 24 h p.i. Though bone uptake was initially similar with both the preparations, there was substantial decrease in bone activity after 24 h p.i. with 186/188Re(V)‐DMSA (MBS). In vitro cell uptake studies were carried out with 186/188Re(V)‐DMSA (MBS), 186/188Re(V)‐DMSA (SnCl2) and 99mTc(V)‐DMSA using Ehrlich Ascites Tumor Cell Lines. Approximately 15% cell uptake was observed with 186/188Re(V)‐DMSA (MBS) as well as with 186/188Re(V)‐DMSA (SnCl2) and was comparable with that of 99mTc(V)‐DMSA (19%). Our studies indicate that 186/188Re(V)‐DMSA prepared by using metabisulfite as a reducing agent has potential for use in targeted radiotherapy of medullary thyroid carcinoma. Copyright © 2002 John Wiley & Sons, Ltd.
Water relaxation by SPM particles: Neglecting the magnetic anisotropy? A caveat
Authors: Roch Alain , Muller Robert N. , Gillis Pierre 
Published: September 2002

AbstractMagnetometric and relaxometric data from SPM particles are revisited, leading to a double conclusion rather different from the original one: accounting for the anisotropy energy not only allows a considerable improvement of the fit of the data to theory, but it also invalidates the conclusion obtained from the high field data (without accounting for anisotropy) concerning an important reduction of the diffusion coefficient by the coating of the particles. J. Magn. Reson. Imaging 2001;14:94–96. © 2001 Wiley‐Liss, Inc.
Solvation of acylium fragment ions in electrospray ionization quadrupole ion trap and Fourier transform ion cyclotron resonance mass spectrometry
Authors: Guan Ziqiang , Liesch Jerrold M. 
Published: September 2002

AbstractIn electrospray ionization (ESI) quadrupole ion trap and Fourier transform ion cyclotron resonance mass spectrometry, certain fragment ions (e.g. acylium ions) generated either during the ion transportation process (in the source interface region) or in the ion trap are found to undergo ion–molecule reactions with ESI solvent molecules (water, acetonitrile and aliphatic alcohols) to form adduct species. These unexpected solvated fragment ions severely complicate the interpretation of mass spectrometic data. High‐resolution accurate mass measurements are important in establishing the elemental compositions of these adduct species and preventing erroneous data interpretation. Copyright © 2001 John Wiley & Sons, Ltd.
Multiphoton ionization and ab initio calculation of the hydrogen‐bonded clusters (C5H5N)n(NH3)m
Authors: Hu Yongjun , Lu Richang , Cai Yong , Wang Xiuyan 
Published: September 2002

AbstractMultiphoton ionization of pyridine–ammonia binary clusters was studied using a time‐of‐flight mass spectrometer at 532 nm laser wavelength. The experimental results showed that the main products of the cluster ionization were the protonated cluster ions [(Py)n(NH3)mH]+. The proton transfer in the multiphoton ionization process is discussed. The hypervalent cluster ions [(Py)(NH3)nH2]+ (n = 1–4) were observed in the experiment and their formation mechanism, the geometric structures and the binding energies are discussed. The results of the theoretical calculation were in agreement with the experimental observations that the binary cluster ions [(Py)3NH4]+ and [(Py)4NH4]+ were the ‘magic number’ ions. Copyright © 2001 John Wiley & Sons, Ltd.
Sequence information, distinction and quantitation of C‐terminal leucine and isoleucine in ternary complexes of tripeptides with Cu(II) and 2,2′‐bipyridine
Authors: Vaisar Tomáš , Gatlin Christine L. , Rao Ramesh D. , Seymour Jennifer L. , Tureček František 
Published: September 2002

AbstractTripeptides form ternary complexes with Cu2+ and 2,2′‐bipyridine (bpy) that self‐assemble upon mixing the components in aqueous methanol solution. Electrospray ionization (ESI) of the complex solutions provides abundant singly charged [Cu(peptide − H)bpy]+ and doubly charged [Cu(peptide)bpy]2+ ions. Collision‐induced dissociation (CID) at low ion kinetic energies of several tripeptides, AGG, GGA, LGG, GGL, GGI, FGG, GGF, LGF, GLF, GFL, GYA and GAY, showed fragments that were indicative of the amino acid sequence in the peptide. In addition, CID of single and doubly charged complexes of isomeric tripeptides GGL and GGI provided unambiguous distinction of the isomeric leucine and isoleucine residues. Leucine peptides eliminated C3H7 radicals from the amino acid side‐chain whereas isoleucine eliminated C2H5 radicals. CID of gas‐phase doubly charged peptide complexes in a quadrupole ion trap produced a series of singly charged sequence fragments that following isolation and further CID furnished distinct fragments that allowed quantitation of leucine and isoleucine‐containing peptides in mixtures. Copyright © 2001 John Wiley & Sons, Ltd.
Equilenin‐2′‐deoxynucleoside adducts: analysis with nano‐liquid chromatography coupled to nano‐electrospray tandem mass spectrometry
Authors: Embrechts Jan , Lemière Filip , Dongen Walter Van , Esmans Eddy L. 
Published: September 2002

AbstractThe interaction of 4‐hydroxy metabolites of estrogens with DNA leads to the formation of DNA adducts. These adducts are believed to play an important role in the incidence of breast and endometrial cancer. In order to be able to analyze these adducts in in vivo samples a method based upon the coupling of miniaturized liquid chromatography (LC) to electrospray tandem mass spectrometry (ES‐MS/MS) was developed for the analysis of the adducts formed with 4‐hydroxyequilenin. In vitro synthesized adducts obtained by the reaction of 4‐hydroxyequilenin with the main 2′‐deoxynucleosides were separated on a Hypersyl C18 BDS nano‐HPLC column (15 cm × 75 µm i.d.) at a flow‐rate of 300 nl min−1 using gradient elution with CH3OH–0.2% CH3COOH in H2O. The column was coupled, in combination with a column switching system, to a nano‐electrospray interface. Analysis of the low‐ and high‐resolution low‐energy collision‐activated dissociation product ion spectra of normal and deuterated adducts supported earlier data demonstrating equilenin to form different isomeric adducts, except with thymidine, for which no adducts were found. The nano‐HPLC column‐switching ES‐MS system was tested for its sensitivity on a triple‐quadrupole instrument, and detection limits down to 197 fg in the single reaction monitoring mode were obtained for semi‐preparatively isolated equilenin–2′‐deoxyguanosine adduct. Copyright © 2001 John Wiley & Sons, Ltd.
MassKinetics: a theoretical model of mass spectra incorporating physical processes, reaction kinetics and mathematical descriptions
Authors: Drahos László , Vékey Károly 
Published: September 2002

AbstractA theoretical framework and an accompanying computer program (MassKinetics, www.chemres.hu/ms/ masskinetics) is developed for describing reaction kinetics under statistical, but non‐equilibrium, conditions, i.e. those applying to mass spectrometry. In this model all the important physical processes influencing product distributions are considered: reactions, including the effects of acceleration, collisions and photon exchange. These processes occur simultaneously and are taken into account by the master equation approach. The system is described by (independent) product, kinetic energy and internal energy distributions, and the time development of these distributions is studied using transition probability functions. The product distribution at the end of the experiment corresponds to the mass spectrum. Individual elements in this scheme are mostly well known: internal energy‐dependent reaction rates are calculated by transition state theory (RRK or RRKM formalisms). In the course of collisions, energy transfer and other processes may occur (the latter usually resulting in the ‘loss’ of ion signal). Collisions are characterized by their probability and by energy transfer in a single collision. To describe single collisions, three collision models are used: long‐lived collision complexes, partially inelastic collisions and partially inelastic collisions with cooling. The latter type has been developed here, and is capable of accounting for cooling effects occurring in collision cascades. Descriptions of photon absorption and emission are well known in principle, and these are also taken into account, in addition to changes in kinetic energy due to external (electric) fields. These changes in the system occur simultaneously, and are described by master equations (a set of differential equations). The usual form of the master equation (taking into account reactions and collisional excitation) was extended to consider also radiative energy transfer, kinetic energy changes, energy partitioning and ion loss collisions. Initial results show that close to experimental accuracy can be obtained with MassKinetics, using few or no adjustable parameters. The model/program can be used to model almost all types of mass spectrometric experiments (e.g. MIKE, CID, SORI and resonant excitation). Note that it was designed for mass spectrometric applications, but can also be used to study reaction kinetics in other non‐equilibrium systems. Copyright © 2001 John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization, fast atom bombardment and plasma desorption mass spectrometry of polyethylene glycol esters of (2‐benzothiazolon‐3‐yl)acetic acid
Authors: Mincheva Zoia , Hadjieva Petia , Kalcheva Veneta , Seraglia Roberta , Traldi Piero , Przybylski Michael 
Published: September 2002

AbstractFast atom bombardment (FAB), matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) and plasma desorption (PD) mass spectra of newly synthesized polyethylene glycols (PEGs), (Mw 600–4000 Da) chemically modified with biologically active (2‐benzothiazolon‐3‐yl)acetyl end‐groups are described (products 1–6). The spectra were also used for the determination of the molecular mass characteristics (number average (Mn) and weight average (Mw) molecular masses) of the initial and modified PEGs. As expected, Mn and Mw of the modified samples are higher than those of the nonmodified samples. However, it is shown that molecular mass dispersity (determined by the comparison of the polydispersity indices (PDI = Mw/Mn) of both types of PEGs) essentially do not change during this modification. The FAB mass spectra, together with molecular species, show the presence of abundant [M + Na]+ ions of product 1 and [M + Na + H]+ species of 2 and 3, and [M + Na + 2H]+ of product 4. Two main series of fragment ions, derived from the cleavage of the ether bonds, are observed. The number fractions of the molecular adduct ions and fragment adduct ions, determined from the FAB and PD mass spectra of the modified PEGs, are compared. The MALDI‐TOF mass spectra of compounds 1–6 show the presence of two series of polymers. The most abundant peaks are due to [M + Na]+ and [M + K]+ ions originating from the polymers, in which the two terminal hydroxyl groups of PEGs are esterified with (2‐benzothiazolon‐3‐yl)acetic acid. The less abundant peaks are due to the monosubstituted polymers. Copyright © 2001 John Wiley & Sons, Ltd.
Capabilities of static TOF‐SIMS in the differentiation of first‐row transition metal oxides
Authors: Aubriet Frédéric , Poleunis Claude , Bertrand Patrick 
Published: September 2002

AbstractTime‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) analyses were performed on the first‐row transition metal oxides from scandium to zinc in positive and negative detection modes. The nature of the numerous MxOy+/− ionic species generated by 15 keV Ga+ primary ion bombardment allows the identification of a given metal–oxygen system. To identify the metal valence in the oxide under investigation, several procedures were investigated: the detection of specific and characteristic ions, the use of ion abundance ratios and the use of a valence model. Owing to their importance in many fields of materials science, each of these speciation methodologies was evaluated for the differentiation of vanadium, titanium, chromium, manganese, iron, cobalt and copper oxides. Trivalent–hexavalent chromium distinction was first intensely investigated because it really corresponds to a model system for inorganic speciation. For each series of metal oxides, the more pertinent speciation criteria were then systematically tested. The limitations of the proposed methodologies are discussed. Their use is made complicated when pollutants or a superficial oxide layer, with a stoichiometry different from that of the bulk, are present. Finally, thermodynamic considerations relative to the stability of the MxOy+/− ions may also modify the relationship between the analyzed oxide and the observed positive and negative secondary ion mass spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Validated assay for quantification of oxcarbazepine and its active dihydro metabolite 10‐hydroxycarbazepine in plasma by atmospheric pressure chemical ionization liquid chromatography/mass spectrometry
Authors: Maurer Hans H. , Kratzsch Carsten , Weber Armin A. , Peters Frank T. , Kraemer Thomas 
Published: September 2002

AbstractOxcarbazepine (OX), a new antiepileptic, may lead to unwanted side‐effects or even life‐threatening intoxications after overdose. Therefore, a validated liquid chromatographic/mass spectrometric (LC/MS) assay was developed for the quantification of OX and its pharmacologically active dihydro metabolite (dihydrooxcarbazepine, DOX, often named 10‐hydroxycarbazepine). OX and DOX were extracted from plasma by the authors' standard liquid/liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. The compounds were quantified in the selected‐ion monitoring mode using atmospheric pressure chemical ionization electrospray LC/MS. The assay was fully validated. It was found to be selective. The calibration curves were linear from 0.1 to 50 mg l−1 for OX and DOX. Limits of quantification were 0.1 mg l−1 for OX and DOX. The absolute recoveries were between 60 and 86%. The accuracy and precision data were within the required limits. The analytes in frozen plasma samples were stable for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with OX. The measured therapeutic plasma levels ranged from 1 to 2 mg l−1 for OX and from 10 to 40 mg l−1 for DOX. The validated LC/MS assay proved to be appropriate for quantification of OX and DOX in plasma for clinical toxicology and therapeutic drug monitoring purposes. The assay is part of a general analysis procedure for the isolation, separation and quantification of various drugs and for their full‐scan screening and identification. Copyright © 2002 John Wiley & Sons, Ltd.
Mass spectrometric characterization of substituted 2‐thiazolin‐4‐one derivatives
Authors: Giorgi Gianluca , Salvini Laura , Attanasi Orazio A. , Filippone Paolino , Santeusanio Stefania 
Published: September 2002

AbstractElectron ionization mass spectrometry was used for the structural characterization of substituted 2‐thiazolin‐4‐one derivatives in the gas phase. The compounds follow common fragmentation pathways, producing ions whose abundances are dependent on the chemical nature of the substituent at position 2. Collision‐induced dissociation tandem mass spectrometric experiments, carried out on both molecular ions and fragment ions produced in the source, allowed the elucidation of gas‐phase decompositions. The presence of tautomeric forms is suggested for some ionic species. Rapid identification of a primary or secondary amine moiety at position 2 of the thiazoline ring can be achieved by the detection of characteristic fragmentations occurring both in the ion source and under the collision‐induced dissociation regime. Copyright © 2002 John Wiley & Sons, Ltd.
Decomposition of multicomponent mass spectra using Bayesian probability theory
Authors: Kang H. D. , Preuss R. , Schwarz‐Selinger T. , Dose V. 
Published: September 2002

AbstractWe present a method for the decomposition of the mass spectra of mixed gases using Bayesian probability theory. The method works without any calibration measurement and therefore applies also to the analysis of spectra containing unstable species. For the example of mixtures of three different hydrocarbon gases the algorithm provides concentrations and cracking coefficients of each mixture component and also their confidence intervals. The amount of information needed to obtain reliable results and its relation to the accuracy of our analysis are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Qualitative characterization of biomolecular zinc complexes by collisionally induced dissociation
Authors: Afonso Carlos , Hathout Yetrib , Fenselau Catherine 
Published: September 2002

AbstractNanospray and collisionally induced dissociation (CID) on a quadrupole/time‐of‐flight mass spectrometer were used to examine the complexes formed between the zinc ion binding protein metallothionein and a series of peptides related to glutathione. The objective of the study was to determine if CID could be used to distinguish complexes that are stabilized by co‐chelation of a zinc ion from non‐covalent complexes that were formed in some other way. Differences in the collision energy required for dissociation and, more importantly, differences in the distribution of zinc ions between the pairs of dissociation products suggest that mass spectrometry can provide qualitative information about the bimolecular chelation of metal ions. The potential application to zinc chelates is particularly important, since biological chelates do not provide signals directly detectable by NMR, Mössbauer or other spectroscopies. The observations reported here also allowed a molecular mechanism to be proposed to explain the differences observed by others in the physiological interactions of reduced and oxidized glutathione with metallothionein. Copyright © 2002 John Wiley & Sons, Ltd.
Trend of hepatitis B virus infection in freshmen classes at two high schools in Hualien, Taiwan from 1991 to 1999
Authors: Lin Hans Hsienhong , Lin Sherry S.J. , Chiang Yu‐Ming , Wang Li‐Yu , Huang Lu‐Chin , Huang Shi‐Che , Liu Tso‐Tsa 
Published: September 2002

AbstractTaiwan is an endemic area of hepatitis B virus (HBV) infection. A nationwide mass vaccination program to prevent HBV infection was started in 1985. Perinatal and horizontal transmission of HBV decreased substantially after the launching of this program. However, the influence of this program on children born before 1985 has not been studied. From 1991 to 1999, annual surveys of hepatitis B virus surface antigen (HBsAg) and antibody (anti‐HBs) were carried out in freshmen at two high schools in Hualien, Taiwan. The average age was 16 years old. Although these students were born 2–10 years after the start of the national HBV vaccination program, there is a significant trend of decreasing HBsAg carrier rate (from 21.0% to 10.5% in males and 14.3% to 4.7% in females) and increasing anti‐HBs rate (from 56.6% to 67.8% in males and 70.3% to 75.9% in females) over the 9 years. With yearly comparison, the carrier rate of HBsAg started to show significant decrease since 1994, while the anti‐HBs began to rise significantly after 1996, especially in male students. The HBsAg carrier rate in male students was significantly higher, while the anti‐HBs rate was significantly lower, than that in female students in most of the years. It is concluded that the effect of HBV vaccination also reduced horizontal transmission of HBV to children born up to 7 years before the start of the program. J. Med. Virol. 67:472–476, 2002. © 2002 Wiley‐Liss, Inc.
Preponderance of hepatitis B virus genotype B contributes to a better prognosis of chronic HBV infection in Okinawa, Japan
Authors: Sakugawa Hiroshi , Nakasone Hiroki , Nakayoshi Tomofumi , Orito Etsuro , Mizokami Masashi , Yamashiro Tsuyoshi , Maeshiro Tatsuji , Kinjo Fukunori , Saito Atsushi , Miyagi Yasuhiro 
Published: September 2002

AbstractThe present study was designed to examine the distribution of hepatitis B virus (HBV) genotypes among patients at various stages of chronic liver disease type B in Okinawa Prefecture, Japan, where the prevalence of hepatitis B surface antigen is the highest in Japan despite the lowest mortality rate from primary liver cancer. Serum samples from 227 HBV carriers were determined for HBV genotype by polymerase chain reaction (PCR)‐restriction fragment length polymorphism. Five of 227 sera were negative for HBV DNA by nested PCR and were excluded from the genotype analysis. Genotype B was predominant in asymptomatic carriers (45/67, 67%), whereas genotype C was predominant in chronic liver disease: 49% (50/103) in patients with chronic hepatitis, 63% (20/32) in patients with cirrhosis, and 60% (12/20) in patients with hepatocellular carcinoma. The distribution of genotype B decreased with increasing liver disease severity. However, this tendency was seen among patients aged less than 50 years old, whereas the prevalence of genotype B was similar among carriers with various liver diseases who were older than age 50. In conclusion, HBV genotype B was prevalent and less frequent among patients with advanced liver disease, particularly in patients aged less than 50 years. These findings suggest that the preponderance of genotype B is responsible for the low mortality rate of primary liver cancer associated with HBV seen in Okinawa Prefecture, despite having the highest HBV carrier rate in Japanese. J. Med. Virol. 67:484–489, 2002. © 2002 Wiley‐Liss, Inc.