bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonuniform flow dynamics in the aorta of normal children: A simplified approach to measurement using magnetic resonance velocity mapping
Authors: Fogel Mark A. , Weinberg Paul M. , Haselgrove John 
Published: August 2002

AbstractPurposeTo determine regional flow dynamics in the normal aorta (Ao) in children. Understanding flow dynamics in children is important in cardiovascular energetics, in designing improved aortic reconstructions by crafting the surgery to mimic normal aortic flow, and in Doppler flow calculations.The objective of this study was to determine regional flow dynamics in the normal Ao in children.Materials and MethodsWe performed magnetic resonance velocity mapping on 13 subjects (ages 7.2 ± 6.2 years) with normal Aos to determine flow dynamics in four equal quadrants in the ascending (AAo) and descending aorta (DAo) aligned along the long axis of the Ao. Statistical significance was set at P < .05.ResultsIn the AAo, the left posterior quadrant displayed significantly less blood flow (16% ± 5%) than the other quadrants (26–29%) over the cardiac cycle. In the DAo, both anterior quadrants carried significantly less blood flow (20% and 21%) than the posterior quadrants (27% and 32%). At maximum flow (15% ± 5% into the cardiac cycle for the AAo; 27% ± 15% for the DAo), there was significantly more flow in the right posterior quadrant (28% ± 2%) than other quadrants (22–23%) in the AAo. In the DAo, both posterior quadrants had significantly higher flow rates (27% and 30%) than the anterior quadrants (21% and 22%). Maximum velocity in both the AAo and the DAo occurred in the left posterior quadrant in 10/13 at 16–24% into the cardiac cycle. At end‐systole, a short flow reversal was noted in the posterior quadrants in the AAo in 11/13; in the DAo, this occurred in the anterior quadrants in 10/13.ConclusionFlow dynamics in the normal Ao in children are not symmetrical; the flow distributions are asymmetric in both the AAo and the DAo throughout systole, including flow reversal related to the dicrotic notch. These results may help improve Ao surgery. J. Magn. Reson. Imaging 2002;15:672–678. © 2002 Wiley‐Liss, Inc.
Year 2000 status of MRI in Mexico
Authors: Rodríguez A. , Rojas R. , Barrios F.A. 
Published: August 2002

AbstractThe development of clinical magnetic resonance imaging in Mexico has followed a different course from that in the U.S. and Europe. The first clinical unit was installed in Mexico in the late 1980s at the very beginning of clinical applications worldwide. Since then, installations have proceeded at a sedate pace that now brings the installed total to 66 imagers. The largest fraction of these units (28, or 42%) is in Mexico City, with a broad distribution across the remaining 23 Mexican states. There is a noticeable increase of the number of units (20, or 30%) in the states bordering the U.S., while the states bordering nations to the south have no units. More than half the units (38, or 58%) are 0.5 T units, while a further 35% are 1.0 T or higher. Slower addition of units in Mexico relative to the U.S. is attributed to the higher fraction of public‐funded hospitals and the inherent conservatism of such institutions when considering new technologies. Present public planning for health care development suggests that the coming decade will see more rapid installation of units to meet growing demand in Mexico for the latest medical technology. Experience over the past two decades indicates the need for more systematic training of technical and clinical personnel to implement these additions. The National University (Universidad Nacional Autónoma de México (UNAM) and the Metropolitan University (Universidad Autónoma Metropolitana (UAM) are collaborating with diverse clinical facilities to create such a program. J. Magn. Reson. Imaging 2001;13:813–817. © 2001 Wiley‐Liss, Inc.
Localization and biopsy of breast lesions by magnetic resonance imaging guidance
Authors: Helbich Thomas H. 
Published: August 2002

AbstractContrast‐enhanced MRI of the breast has proved to be a valuable tool in the detection and work‐up of breast lesions. Most of these lesions are small and not visible by other imaging modalities, such as mammography or US. Thus, only MR‐guided preoperative localization techniques or MR‐guided percutaneous biopsy can provide a histologic work‐up of such lesions. MR‐guided preoperative localization seems to be a well‐established procedure. However, MR‐guided biopsy is still problematic. Although prototypical biopsy systems have been developed, considerable progress is still required. Problems exist with MR‐guided biopsy due to severe needle artifacts and tissue shift during the intervention. Thus, needle biopsy currently is not recommended for lesions smaller than 10 mm. This work reviews current techniques for MR‐guided preoperative localization and percutaneous biopsy in breast lesions. The diagnostic accuracy achievable with these techniques will be discussed, as well as the potential for new research opportunities and directions. J. Magn. Reson. Imaging 2001;13:903–911. © 2001 Wiley‐Liss, Inc.
Discrimination between pentose oligosaccharides containing D‐xylopyranose or L‐arabinofuranose as non‐reducing terminal residue using fast atom bombardment mass spectrometry
Authors: Kováčik Vladimír , Pätoprstý Vladimír , Hirsch Ján 
Published: August 2002

AbstractCollisional‐induced dissociation (CID) mass spectra of the [M + H]+ and [M − H]− ions obtained under fast atom bombardment conditions of a number of methyl glycoside di‐, tri‐ and tetrasaccharides, containing D‐xylopyranosyl and/or L‐arabinofuranosyl residues at the non‐reducing terminus, do not provide information about their ring size. This information could only be obtained from a careful comparison of the intensity ratio of the [M + Na − 90]+ and [M + Na − 104]+ ions (0,2Xt/1,5Xt) in the high‐energy CID spectra of the sodium‐cationized di‐, tri‐ and probably also tetrasaccharide compounds. Copyright © 2001 John Wiley & Sons, Ltd.
On‐line coupling of hollow fiber membranes with electrospray ionization mass spectrometry for continuous affinity selection, concentration and identification of small‐molecule libraries
Authors: Jiang Yun , Lee Cheng S. 
Published: August 2002

AbstractCombinatorial chemistry has been widely employed in the pharmaceutical industry in the effort towards drug discovery. Rapid and sensitive screening of lead candidates among library compounds has thus imposed significant analytical challenges in recent years. This work involved the development of a continuous affinity capture and concentration system, providing cost‐effective and structural analysis of drug candidates in a flow‐through format. The system combines the strengths of a hollow fiber dialysis membrane of ease and speed of purification and concentration with the specificity of affinity interactions in solution. The complexes between the lead compounds and the affinity binding proteins are separated from other chemical components inside a dialysis hollow fiber as the result of their differences in size. The affinity complexes are further concentrated inside a second dialysis fiber. The concentrated drug candidates are liberated from the binding proteins in a microdialysis junction and can be directly identified using electrospray ionization mass spectrometry. Two model systems, including human serum albumin–warfarin‐related compounds and anti‐phenobarbital antibody–barbiturates, were employed for mechanistic studies of dialysis versus dissociation kinetics and competitive selection of drug candidates according to their binding strengths. Copyright © 2001 John Wiley & Sons, Ltd.
Primary and secondary kinetic isotope effects in proton (H+/D+) and chloronium ion (35Cl+/37Cl+) affinities
Authors: Gozzo Fábio Cesar , Eberlin Marcos N. 
Published: August 2002

AbstractThe Cooks' kinetic method and tandem‐in‐space pentaquadrupole QqQqQ mass spectrometry were used to measure primary and secondary kinetic isotope effects (KIEs) in H+ and Cl+ (X+) affinity for a series of A/A′ isotopomeric pairs. Gaseous, isotopomeric, and loosely bound dimers [A···X+···A′] were formed in combinations in which X = H+, D+, 35Cl+ or 37Cl+ and A/A′ = acetonitrile/acetonitrile − d3, acetonitrile/acetonitrile‐15N, acetonitrile‐d3/acetonitrile‐15N, acetone/acetone‐d6, acetone/acetone‐18O, acetone‐d6/acetone‐18O, pyridine/pyridine‐d5, pyridine/pyridine‐15N, pyridine‐d5/pyridine‐15N, or 3‐(35Cl)chloropyridine/3‐(37Cl)chloropyridine. Under nearly the same experimental conditions, the dimers were mass‐selected and then dissociated by low‐energy collisions with argon, yielding AX+ and A′X+ as the fragment ions. KIEs were measured from the changes in ion affinities of the neutrals (ΔX+) as estimated by the AX+/A′X+ abundance ratios. Using [A···H+(D+)···A′] and [A···35Cl+(37Cl+)···A′] dimers and by comparing their extent of dissociation under nearly identical collision‐induced dissociation conditions, the kinetic method was also applied, for the first time, to measure primary KIEs of the central ion as well as their influence on secondary KIEs. Becke3LYP/6‐311++G(2df,2p) calculations were found to provide Δ(ΔZPE)s for the competitive dissociation reactions that accurately predict the nature (normal or inverse) of the measured KIEs. Copyright © 2001 John Wiley & Sons, Ltd.
Products, rate constants and mechanisms of gas‐phase reactions of CX3+, CX2+, CX+ (X = F and/or Cl) and Cl+ with 1,1,1‐ and 1,1,2‐trichlorotrifluoroethane
Authors: Marotta Ester , Paradisi Cristina 
Published: August 2002

AbstractThe gas‐phase ion chemistry of 1,1,1‐ and 1,1,2‐trichlorotrifluoroethane was investigated with an ion trap mass spectrometer. Following electron ionization both compounds (M) fragment to [M − Cl]+, CX3+, CX2+, CX+ (X = F and/or Cl) and Cl+. The reactivity of each of these fragments towards their neutral precursors was studied to obtain product and kinetic data. Whereas [M − Cl]+, CCl3+ and CCl2F+ cations are unreactive under the experimental conditions used, all other species react via halide abstraction to give [M − Cl]+ and, to a far lesser extent, [M − F]+. In addition, CX2+ ions form CClX2+ in a process which formally amounts to chlorine atom abstraction, but more likely involves chloride ion abstraction followed by charge transfer. CX+ ions also form minor amounts of CX3+ product ions, possibly via chloride abstraction followed by or concerted with dihalocarbene elimination from the (incipient) [M − Cl]+ ion. Trivalent carbenium ions are less reactive than divalent species, which in turn are less reactive than the monovalent ions (reaction efficiencies are given in parentheses): CF3+(0.70) < CF2+(0.78) < CF+(0.96). More interestingly, within each family of ions reactivity increases with the number of fluorine substituents (e.g. CF2+ > CFCl+ > CCl2+ and CF+ > CCl+), i.e. reactivity increases with the ion thermochemical stability, as measured by available standard free enthalpies of formation. Evaluation of the energetics involved shows that reactions are largely driven by the stability of the neutrals more than of the ions. Finally, the products observed in the reaction of Cl+ are attributed to ionization of the neutral via charge transfer and fragmentation. Copyright © 2001 John Wiley & Sons, Ltd.
Phase I metabolism of ganstigmine. Rat, dog, monkey and human liver microsomal extracts investigated by liquid chromatography electrospray tandem mass spectrometry
Authors: Silvia Catinella , Nicola Pelizzi , Paola Puccini , Silvia Marchetti , Margherita Zanol , Daniela Acerbi , Paolo Ventura 
Published: August 2002

AbstractGanstigmine, a new acetylcholinesterase inhibitor, was incubated with rat liver microsomes and the resulting metabolites were identified by high‐performance liquid chromatographic/mass spectrometric (HPLC/MS) and HPLC/MS/MS analyses. The results showed the formation of eight main metabolites, among which geneseroline and molecules corresponding to mono‐hydroxylated, demethylated and reduced ganstigmine. The metabolic profile drawn for humans, dog and monkey showed a pattern very similar to that of rat: only in the case of liver dog microsomes higher amounts of geneseroline and of a metabolite identified as demethylated and reduced drug were detected. Copyright © 2001 John Wiley & Sons, Ltd.
Structural characterization of hexoses and pentoses using lead cationization. An electrospray ionization and tandem mass spectrometric study
Authors: Salpin Jean‐Yves , Tortajada Jeanine 
Published: August 2002

AbstractThe analytical potential of the complexation of isomeric underivatized hexoses (D‐glucose, D‐galactose, D‐mannose, D‐talose, D‐fructose), methylglycosides (1‐O‐methyl‐α‐D‐glucose and 1‐O‐methyl‐β‐D‐glucose) and pentoses (D‐ribose, D‐xylose, D‐arabinose and D‐lyxose) by Pb2+ ions, was investigated by electrospray ionization and tandem mass spectrometry (MS/MS). Pb2+ ions react mainly with monosaccharides by proton abstraction to generate [Pb(monosaccharide)m − H]+ ions (m = 1–3). At low cone voltage, a less abundant series of doubly charged ions of general formula [Pb(monosaccharide)n]2+ is also observed. The maximum number n of monosaccharides surrounding a single Pb2+ ion depends on the metal : monosaccharide ratio. Our study shows that MS/MS experiments have to be performed to differentiate Pb2+‐coordinated monosaccharides. Upon collision, [Pb(monosaccharide) − H]+ species mainly dissociate according to cross‐ring cleavages, leading to the elimination of CnH2nOn neutrals. The various fragmentation processes observed allow the C(1), C(2) and C(4) stereocenters of aldohexoses to be characterized, and also a clear distinction aldoses and fructose. Furthermore, careful analysis of tandem mass spectra also leads to successful aldopentose distinction. Lead cationization combined with MS/MS therefore appears particularly useful to identify underivatized monosaccharides. Copyright © 2002 John Wiley & Sons, Ltd.
Substituent effect and multisite protonation in the fragmentation of alkyl benzoates
Authors: Denekamp Chagit , Stanger Amnon 
Published: August 2002

AbstractThe dissociation of protonated alkyl benzoates (para H, CN, OMe and NO2) into protonated benzoic acids and alkyl cations was studied in the gas phase. It was found that the product ratio depends on the substituent at the para position of the phenyl ring. The substituent effect is probably the result of the formation of an ion–neutral complex intermediate that decomposes to an ion and a neutral, according to the relative proton affinities of the two moieties. The experimental results and theoretical calculations indicate that the favored protonation site in these compounds is the ester's carbonyl and that proton transfer from the phenyl ring to the ester group is very likely to occur under chemical ionization conditions. It is most probable that the carbonyl protonated form is a common intermediate in the fragmentation process, regardless of the protonation site. Copyright © 2002 John Wiley & Sons, Ltd.
Fragmentation characteristics of peptide–metal ion adducts under matrix‐assisted laser desorption/ionization post‐source decay time‐of‐flight mass spectrometric conditions
Authors: Jayawardene Dhammika , Dass Chhabil 
Published: August 2002

AbstractFragmentation reactions of sodium‐cationized enkephalin peptides generated by matrix‐assisted laser desorption/ionization were studied using post‐source decay (PSD) with a reflectron time‐of‐flight mass spectrometer. Several matrices and analyte–matrix sample preparation methods were evaluated for high‐intensity ion currents that could last for the entire PSD analysis. A triple dried‐droplet sample preparation procedure with 2,5‐dihydroxybenzoic acid as the matrix was found to yield abundant longer‐lasting ion signals of the peptide–Na+ ion adducts. The principal decay product of these adduct ions is the [bn−1 + Na + OH]+ ion, which provides an unambiguous identification of the C‐terminal residue of a peptide. In some peptides, the loss of a second residue from the C‐terminus is also observed. No other sequence‐specific ions were observed. Copyright © 2002 John Wiley & Sons, Ltd.
Histopathologic impact of TT virus infection on the liver of type C chronic hepatitis and liver cirrhosis in Japan
Authors: Moriyama Mitsuhiko , Matsumura Hiroshi , Shimizu Toshihiro , Shioda Atsuo , Kaneko Miki , Miyazawa Kouji , Miyata Hajime , Tanaka Naohide , Uchida Toshikazu , Arakawa Yasuyuki 
Published: August 2002

AbstractThe present investigation compared the histological findings in the liver of chronic hepatitis C patients who were or were not co‐infected with TT virus (TTV) to determine the histological and clinical characteristics of TTV infection. One hundred eighty patients with chronic hepatitis or liver cirrhosis type C were included in this study. Serum samples were tested for the presence of TTV DNA by a nested polymerase chain reaction. The liver biopsy specimen of each patient was examined, and scores were assigned to indicate the severity of each of the following features: inflammatory cell infiltration in the periportal, parenchymal, and portal areas; fibrous stage; lymphoid reaction in the portal area; portal sclerotic change; perivenular fibrosis; pericellular fibrosis; damage of bile duct; and irregular regeneration of hepatocytes. Sixty‐four (34.4%) of the 180 patients were positive for TTV DNA. The histological features of the liver and the blood biochemical parameters of the TTV DNA‐positive and TTV DNA‐negative patients, did not differ significantly except for the score of irregular regeneration (IR) of hepatocytes. Among those in the F4 stage of fibrosis, the score of IR of the TTV DNA‐positive patients was significantly higher than that of the TTV DNA‐negative patients. In conclusion, chronic TTV infection does not modify the biochemical features of chronic hepatitis type C patients. TTV may be a risk factor, however, for the development of hepatocellular carcinoma in patients with type C liver disease in the F4 stage. J. Med. Virol. 64:74–81, 2001. © 2001 Wiley‐Liss, Inc.
Isolated anti‐HBc in chronic hepatitis C predicts a poor response to interferon treatment
Authors: Sagnelli Evangelista , Coppola Nicola , Scolastico Carlo , Mogavero Anna Rita , Stanzione Maria , Filippini Pietro , Felaco Francesca Maria , Piccinino Felice 
Published: August 2002

AbstractThe sustained response to interferon‐α treatment was evaluated in 147 anti‐HCV/HCV‐RNA‐positive, HBsAg‐negative, chronic hepatitis patients, according to HCV genotypes and the presence or absence of anti‐HBs and anti‐HBc. These patients had been included in a controlled study on the safety, tolerability, and efficacy of three types of interferon‐α given at a dose of 3 MU three times weekly for 52 weeks. One hundred and two patients had HCV genotype 1, 42 a non‐1 HCV genotype and 3 multiple HCV genotypes; 46 were anti‐HBs and anti‐HBc negative (group A), 50 anti‐HBs and anti‐HBc positive (group B), and 51 anti‐HBs negative and anti‐HBc positive (“isolated” anti‐HBc, group C). Serum HBV‐DNA was detected by polymerase chain reaction in 15 of the 51 (29.4%) patients in group C and in none of those in groups A or B. The Sustained Response rate was higher in patients with a non‐1 HCV genotype than those with HCV genotype 1 (31% vs. 17.7%, P > 0.1). Fewer patients in group C showed a sustained response than in group A or group B (7.8% vs. 30.4%, P = 0.009 and 7.8% vs 28%, P = 0.017, respectively). Moreover, the sustained response rate was high in patients with a non‐1 genotype, both in group A (42.8%) and in group B (42.8%), intermediate in patients with HCV genotype 1 (23.3% in group A and 22.2% in group B) and low in group C, irrespective of HCV genotype (8.3% for genotype 1 and 7.1% for other genotypes). The data indicate that patients with HCV chronic hepatitis and isolated anti‐HBc show a poor response to IFN‐α, irrespective of the HCV genotype. J. Med. Virol. 65:681–687, 2001. © 2001 Wiley‐Liss, Inc.
Parenteral and oral immunization with a plasmid DNA expressing the human papillomavirus 16‐L1 gene induces systemic and mucosal antibodies and cytotoxic T lymphocyte responses
Authors: Rocha‐Zavaleta Leticia , Alejandre Jorge E. , Garcia‐Carranca Alejandro 
Published: August 2002

AbstractThe association of human papillomavirus (HPV) infection and cervical cancer has been demonstrated. The development of a prophylactic vaccine to protect against primary HPV infection may therefore be an efficient means to reduce the incidence of this cancer worldwide. To assess the capacity of a plasmid DNA that expresses the L1 gene of HPV type 16 to induce a protective immune response, mice were immunized by parenteral and oral routes. Animals that received the DNA vaccine intramuscularly, subcutaneously and orally, developed systemic anti‐L1 IgG antibodies. Antibodies developed in mice vaccinated subcutaneously were detectable twelve months post‐immunization. Specific IgA antibodies were also found in vaginal washes from immunized mice. Both systemic and local antibodies proved effective in a surrogate neutralization assay. Splenic T cells extracted from experimental mice showed cytotoxic T lymphocytes (CTL) activity mediated by CD8 + cells. Mice were challenged with a syngeneic melanoma cell line, engineered to express the HPV16‐L1 protein, tumours in vaccinated animals showed slower growth rate, correlated directly with a longer survival of mice. The results suggest that the L1‐based DNA vaccine may be useful for the prevention of primary infections by HPV16. J. Med. Virol. 66:86–95, 2002. © 2002 Wiley‐Liss, Inc.
Characteristics of Epstein‐Barr virus isolated from the malignant lymphomas in Korea
Authors: Kim Insun , Park Eui‐Ryun , Park Seol‐Hee , Lin Zhenhua , Kim Young‐Sik 
Published: August 2002

AbstractEpstein‐Barr virus (EBV) is a common herpes virus linked to a variety of human neoplasms. In this study, the EBV detection was identified with the paraffin‐embedded tissues from 62 non‐Hodgkin's lymphomas, 20 Hodgkin's lymphomas, and 48 non‐neoplastic tonsils, using PCR for EBNA‐1 and EBER‐1 mRNA in situ hybridization for EBER‐1 mRNA. The isolates were analyzed for type 1/2, variants C/D and F/f, and LMP‐1 30 bp deletion. EBV was isolated in 31 of 48 (66%) non‐neoplastic tonsils, 24 of 42 (57%) B cell lymphomas, in 15 of 20 (75%) T cell lymphomas, and 17 of 20 (85%) Hodgkin's lymphomas. These viruses were classified as type 1 for 81% of non‐neoplastic tonsils, 95% of B cell lymphomas, 93% of T cell lymphomas, and 73% of Hodgkin's diseases. Both type 1 and 2 viruses were isolated in one non‐neoplastic tonsil and 3 Hodgkin's diseases. Type C virus was predominant in non‐neoplastic tonsils (77%) and B cell lymphomas (75%), while type D virus was common in T cell lymphomas (71%) and Hodgkin's diseases (73%) (P < 0.05). Majority of the viruses detected in non‐neoplastic tonsils (93%) and malignant lymphomas (91%) were “F” prototype. LMP‐1 30 bp deletion was found in high frequency in both non‐neoplastic tonsils (92%) and malignant lymphomas (86%). In conclusion, most of EBV found in Korea was type 1, and “DF” genotype was more frequent in T cell lymphomas and Hodgkin's diseases than in non‐neoplastic tonsils and B cell lymphomas. LMP‐1 30 bp deletion did not seem to be associated with malignant lymphomas. J. Med. Virol. 67:59–66, 2002. © 2002 Wiley‐Liss, Inc.