bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution of VCAF‐positive cells to neovascularization and calcification in atherosclerotic plaque development
Authors: Wilkinson FL , Liu Y , Rucka AK , Jeziorska M , Hoyland JA , Heagerty AM , Canfield AE , Alexander MY
Published: December 2006

Calcification of the vessel wall is a regulated process with many similarities to osteogenesis. Progenitor cells may play a role in this process. Previously, we identified a novel gene, Vascular Calcification Associated Factor (VCAF), which was shown to be important in pericyte osteogenic differentiation. The aim of this study was to determine the localization and expression pattern of VCAF in human cells and tissues. Immunohistochemical analysis of seven atherosclerotic arteries confirmed VCAF protein expression within calcified lesions. In addition, individual VCAF‐positive cells were detected within the intima and adventitia in areas where sporadic 3G5‐positive pericytes were localized. Furthermore, VCAF‐positive cells were identified in newly formed microvessels in association with CD34‐positive/CD146‐positive/c‐kit‐positive cells as well as in intact CD31‐positive endothelium in internal mammary arteries. Western blot analysis confirmed the presence of VCAF (18 kD) in protein lysates extracted from human smooth muscle cells, endothelial cells, macrophages, and osteoblasts. In fracture callus samples from three patients, VCAF was detected in osteoblasts and microvessels. This study demonstrates the presence of VCAF in neovessels and raises the possibility that VCAF could be a new marker for vascular progenitor cells involved in a number of differentiation pathways. These data may have implications for the prevention or treatment of vascular disease. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Parvovirus B19 infection in pregnancy: maternal and fetal viral load measurements related to clinical parameters
Authors: de Haan Timo R. , Beersma Matthijs F. C. , Oepkes Dick , de Jong Eveline P. , Kroes Aloys C. M. , Walther Frans J.
Published: December 2006

Objective

To correlate quantitative maternal and fetal parvovirus B19 (B19V) viral loads and antibody levels at intrauterine transfusion (IUT) as a predictor of fetal morbidity.

Methods

Prospectively collected clinical data and quantitative B19V viral load and specific IgM and IgG values in fetal and maternal blood samples taken during IUT.

Results

Maternal IgM and IgG levels exceeded fetal antibody levels. Fetal viral load measurements correlated positively with maternal viral loads and exceeded maternal viral load 105‐fold (p < 0.0001). Maternal B19V IgM and fetal B19V viral load showed a positive correlation (r = 0.840, p = 0.007). No relation was found between fetal viral load and severity of fetal anemia derived from Doppler flow measurements in the middle cerebral artery.

Conclusions

Maternal and fetal B19V viral load values are highly interrelated, suggesting continuous maternal and fetal viral replication or a fetal source of maternal viremia. Maternal B19V IgM values may predict the severity of fetal infection, but the severity of B19V induced fetal anemia cannot be predicted using fetal or maternal viral loads. Fetal ultrasound remains the gold standard for identifying fetal anemia in B19V infection. Copyright © 2007 John Wiley & Sons, Ltd.
Prenatal diagnosis of muscle‐eye‐brain disease
Authors: Balci Burcu , Morris‐Rosendahl Deborah J. , Çelebi Asli , Talim Beril , Topaloǧlu Haluk , Dinçer Pervin
Published: December 2006

Objectives

To present a family in which it was possible to perform prenatal diagnosis for the recessively inherited muscle‐eye‐brain disease (MEB) using linkage analysis.

Methods

Linkage analysis and direct sequencing of the POMGNT1 gene were carried out in a Turkish MEB family with one affected individual. Fetal DNA was obtained from an ongoing pregnancy by chorionic villus sampling (CVS).

Results

Both linkage analysis of the POMGNT1/1p32‐p34 region and direct sequencing for the novel familial mutation (R605H) demonstrated that the fetus did not have MEB.

Conclusion

We report the first case of prenatal diagnosis in MEB by molecular genetic analysis. Copyright © 2007 John Wiley & Sons, Ltd.
FISH analysis of 15 chromosomes in human day 4 and 5 preimplantation embryos: the added value of extended aneuploidy detection
Authors: Baart E. B. , van den Berg I. , Martini E. , Eussen H. J. , Fauser B. C. J. M. , Opstal D. Van
Published: December 2006

Objective

Screening for an increased number of chromosomes may improve the detection of abnormal embryos and thus contribute to the capability of preimplantation genetic screening (PGS) to detect the embryo(s) for transfer in IVF with the best chance for a healthy child. Good‐quality day 4 and 5 embryos were analyzed after cryopreservation for the nine chromosomes mostly recommended for screening (13, 14, 15, 16, 18, 21, 22, X and Y), next to six additional chromosomes which are less well studied in this context (1, 2, 7, 6, 10 and 17).

Method

The copy numbers of 15 chromosomes were investigated by fluorescence in situ hybridization (FISH) in three consecutive rounds. The proportion of aneuploid and mosaic embryos was determined and compared in retrospect to results in case only the recommended probe set had been analyzed.

Results

A total of 52 embryos from 29 infertile women were analyzed. Screening the embryos for six additional chromosomes increased the proportion of abnormal embryos from 67 to 81% (P = 0.03), owing to an increase in mosaic embryos.

Conclusion

All but one of the meiotic aneuploidies found in this study would have been detected by the probe set most frequently used in PGS clinics. However, aneuploid cell lines originating from mitotic errors could be detected for almost all chromosomes, so screening of six additional chromosomes mainly increased the proportion of mosaic embryos. The added value of screening for six additional chromosomes in PGS for clinical practice will remain undetermined as long as the fate of mosaic embryos after transfer is unclear. Copyright © 2007 John Wiley & Sons, Ltd.
Is there an association between maternal ABO and rhesus blood groups and the first‐trimester serum markers free β‐hCG and PAPP‐A used for the detection of fetal aneuploidy?
Authors: Cowans Nicholas J. , Spencer Kevin
Published: December 2006

Objectives

To evaluate whether first‐trimester levels of PAPP‐A and serum free‐β‐human chorionic gonadotrophin (free β‐hCG) vary with maternal blood group and rhesus status and to assess whether this has implications for first‐trimester screening for chromosomal anomalies.

Methods

Blood group and rhesus status information was extracted from birth records for women undergoing first‐trimester screening. The birth records were combined with prenatal screening records by an in‐house developed record linkage software. In 2252 singleton pregnancies of normal obstetric outcome, the median weight‐corrected, ethnicity‐corrected and smoking‐corrected MoM were compared in the various blood groups, using t‐tests after log10 transformation of the marker MoM against the whole study group.

Results

Only those women with a B rhesus positive blood group had statistically significant higher MoM levels of PAPP‐A (0.995 v 0.937).

Conclusions

A larger study is required to establish the validity of this increase in PAPP‐A in the B rhesus positive group. If this can be substantiated, the elevation in PAPP‐A in this group may require correction when screening for chromosomal anomalies. Copyright © 2007 John Wiley & Sons, Ltd.
Prenatal diagnosis in myotonic dystrophy type 1. Thirteen years of experience: implications for reproductive counselling in DM1 families
Authors: Martorell Loreto , Cobo Ana Maria , Baiget Montserrat , Naudó Montserrat , Poza Juan José , Parra Juan
Published: December 2006

Objectives

To analyse the results obtained from prenatal diagnoses in myotonic dystrophy type 1 (DM1) performed in our hospitals during the last 13 years.

Methods

Molecular analyses were conducted on chorionic villi or cultured amniotic fluid samples obtained for prenatal diagnosis of DM1. CTG expansion was analyzed by polymerase chain reaction (PCR) and Southern blot techniques.

Results

From 154 prenatal diagnoses performed in 13 years, 51% were found to be healthy and 49% affected. Considering the 75 carriers of the mutation, in 65.3% of the cases, the mother was the transmitting parent versus 36.5% of fathers. From these female transmissions, 31/49 foetuses had expansion in the neonatal form range, namely, congenital myotonic dystrophy (CMD).

Conclusions

In our series, no significant deviation of the 50% expected frequency of transmission in autosomal dominant disorder was seen. We show that when the disease is transmitted by a male, the mean intergenerational variation is minimal (mean = 56 CTG, SD = 177 CTG). However, this does not occur in the affected mothers, where the mean intergenerational expansion is very high (mean = 948 CTG, SD = 815 CTG) and the difference is statistically significant (t‐Student p < 0.0001).

Our data have important implications for the genetic counselling of DM1 families. Copyright © 2007 John Wiley & Sons, Ltd.
First‐trimester fetal limb biometry in Chinese population
Authors: Chen Min , Lee Chin Peng , Lam Yung Hang , Ou Chun Quan , Tang Mary Hoi Yin
Published: December 2006

Objectives

To establish reference ranges for fetal limb biometry obtained by transabdominal ultrasound examination at 12–14 weeks of gestation in Chinese women.

Methods

A total of 1489 normal singleton fetuses between 12+0 and 14+6 weeks of gestation were examined transabdominally by two experienced observers. The gestation was ascertained by measurement of fetal crown–rump length (CRL) or biparietal diameter (BPD) and head circumference (HC). The lengths of the humerus and femur were prospectively worked out.

Results

Gestation‐specific reference ranges for limb measurements were calculated. The femur length (FL) (mean ± SD) was 9.15 ± 1.44 mm at 12–12+6 weeks, 11.45 ± 1.35 mm at 13–13+6 weeks, and 13.64 ± 1.60 mm at 14–14+6 weeks; the corresponding humerus length (HL) (mean ± SD) was 9.63 ± 1.44 mm, 12.01 ± 1.41 mm, 14.29 ± 1.48 mm, respectively.

Conclusions

There was a general increase in fetal limb biometry with gestation. Fetal limb length can be an early marker of early growth restriction as well as fetal skeletal dysplasia among women in the local population. Copyright © 2006 John Wiley & Sons, Ltd.
Comparison of military and civilian reporting rates for smallpox vaccine adverse events
Authors: McMahon A. W. , Zinderman C. , Ball R. , Gupta G. , Braun M. M.
Published: December 2006

Introduction

US smallpox vaccination (SMA) started most recently in December 2002. Military and civilian personnel report adverse events (AEs) to the Vaccine Adverse Event Reporting System (VAERS), a surveillance system that relies on spontaneous reports. Although reported rates of probable myo/pericarditis after SMA in the literature are similar between military personnel and civilian healthcare workers, some civilian AE reporting rates after SMA appeared higher than those in the military.

Objective

Determine if SMA‐associated reporting rates are different in civilians than in the military, considering age, sex, seriousness, and expectedness of the AE, as well as self‐reporting.

Methods

Numerators were SMA reports in VAERS from 12/12/02 to 3/1/04. Limitations of VAERS include underreporting and lack of diagnostic confirmation. Denominators were number of military and civilian vaccinees.

Results

Reporting rates stratified by age and sex of serious and non‐serious AEs were significantly higher in civilian than military personnel ages <55 years (rate ratios 4–27). These rate ratios decreased with increasing age.

Conclusions

Reporting rates in VAERS differed significantly and substantially in civilians compared to military personnel <55 years of age. Differences in stimulated passive surveillance systems, and AE reporting practices, including the ‘threshold’ for reporting most likely explain these findings. These results suggest that in the case of smallpox vaccine AEs, there may be systematic differences in reporting completeness between the civilian and military sectors, and that passive surveillance data should be interpreted with caution. Copyright © 2006 John Wiley & Sons, Ltd.
Hospitalisations and emergency department visits due to drug–drug interactions: a literature review
Authors: Becker Matthijs L , Kallewaard Marjon , Caspers Peter WJ , Visser Loes E , Leufkens Hubert GM , Stricker Bruno HCh
Published: December 2006

Purpose

Our objective was to evaluate the incidence of adverse patient outcomes due to drug–drug interactions (D–DIs), the type of drugs involved and the underlying reason. As a proxy for adverse patient outcomes, emergency department (ED) visits, hospital admissions and re‐hospitalisations were assessed.

Methods

A literature search in the Medline and Embase database (1990–2006) was performed and references were tracked. An overall cumulative incidence was estimated by dividing the sum of the cases by the sum of the study populations.

Results

Twenty‐three studies were found assessing the relationship between D–DIs and ED‐visits, hospitalisations or re‐hospitalisations. The studies with a large study size showed low incidences and vice versa. D–DIs were held responsible for 0.054% of the ED‐visits, 0.57% of the hospital admissions and 0.12% of the re‐hospitalisations. In the elderly population, D–DIs were held responsible for 4.8% of the admissions. Drugs most often involved were NSAIDs and cardiovascular drugs. The reasons for admissions or ED‐visits, which were most often found were GI‐tract bleeding, hyper‐ or hypotension and cardiac rhythm disturbances.

Conclusion

This review provides information on the overall incidence of D–DIs as a cause of adverse patient outcomes, although there is still uncertainty about the impact of D–DIs on adverse patient outcomes. Our results suggest that a limited number of drugs are involved in the majority of cases and that the number of reasons for admission as a consequence of D–DIs seems to be modest. Copyright © 2006 John Wiley & Sons, Ltd.
Polysulfone ionomers functionalized with benzoyl(difluoromethylenephosphonic acid) side chains for proton‐conducting fuel‐cell membranes
Authors: Lafitte Benoît , Jannasch Patric
Published: December 2006

Polysulfones carrying benzoyl(difluoromethylenephosphonic acid) side chains were prepared and investigated for use as proton‐conducting fuel‐cell membranes. In the first step, polysulfones were lithiated and reacted with methyl iodobenzoates to prepare p‐ and o‐iodobenzoyl polysulfones. Next, the phosphonated polysulfones were prepared via CuBr‐mediated cross‐coupling reactions between the iodinated polymer and [(diethoxyphosphinyl)difluoromethyl]zinc bromide. Finally, dealkylation with bromotrimethylsilane afforded highly acidic CF2PO3H2 derivatives. The replacement of the iodine atoms by CF2PO3Et2 units was almost quantitative in the case of o‐iodobenzoyl polysulfone. Membranes based on ionomers having 0.90 mmol of phosphonic acid units/g of dry polymer took up 6 wt % water when immersed at room temperature, and conductivities up to 5 mS cm−1 at 100 °C were recorded. This level of conductivity was comparable to that reached by a membrane based on a sulfonated polysulfone having 0.86 mmol of sulfonic acid/g of dry polymer. Thermogravimetry revealed that the arylCF2PO3H2 arrangement decomposed at approximately 230 °C via cleavage of the CP bond. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 269–283, 2007.
A novel synthetic peptide vector system for optimal gene delivery to bone marrow stromal cells
Authors: Haitao Pan , Qixin Zheng , Xiaodong Guo
Published: December 2006

A 23‐amino acid, bifunctional, integrin‐targeted synthetic peptide was evaluated for ex vivo gene delivery to rabbit bone marrow stromal cells (BMSCs). The peptide (K)16GRGDSPC consists of an amino terminal domain of 16 lysines for electrostatic binding of DNA, and a 7‐amino acid integrin‐binding domain at the carboxyl terminal. PcDNA3‐EGFP plasmids were transfected into BMSCs by (K)16GRGDSPC and the positive cells gave out a bright green fluorescence. High levels of gene delivery of pcDNA3‐TGF‐β1 plasmids were obtained with 2 to 4 µg/ml DNA concentration, with (K)16GRGDSPC at an optimal peptide: DNA w/w ratio of 3:1, with a required exposure time of more than 4 h but shorter than 24 h for BMSC exposure to the peptide/DNA complexes with completely absent serum in the initial stage; with 100 µM chloroquine and at least 8 h exposure for BMSC exposure to chloroquine; with a fusogenic peptide at an optimal (K)16GRGDSPC/DNA/fusogenic peptide w/w ratio of 3:1:5; and with Lipofectamine 2000 at an optimal (K)16GRGDSPC/DNA/Lipofectamine 2000 w/w ratio of 3:1:2 at a constant DNA concentration of 2 µg/ml. Chloroquine, the fusogenic peptide and Lipofectamine 2000 all significantly promoted gene delivery, but chloroquine was more effective than the fusogenic peptide and had obvious synergistic effects with Lipofectamine 2000. Under optimal conditions, TGF‐β1 gene was transfected into BMSCs without observable toxicity, and the stable expression was examined by RT‐PCR and Western blot analysis. The stable transgenic cells showed obvious bands. This novel synthetic peptide, providing a new way for the use of polylysine and RGD motif in DNA vector system, is potentially well suited to ex vivo gene delivery to BMSCs for experimental and clinical applications in the field of bone tissue engineering. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis and characteristics of MgO nanowires on Ag‐coated substrates
Authors: Kim Hyoun Woo , Shim Seung Hyun
Published: December 2006

The production of magnesium oxide (MgO) nanowires on Ag‐coated substrates was demonstrated by the thermal evaporation of MgB2 powders. Scanning electron microscopy revealed that the product consisted of nanowires with average diameter in the range 80–120 nm. X‐ray diffraction and high‐resolution electron microscopy coincidentally indicated that the nanowires were of a single‐crystalline cubic structure of MgO. Photoluminescence measurement with a Gaussian fitting exhibited visible light emission bands centered at 431 and 506 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Color centers in gamma‐irradiated YAP crystals grown by the Czochralski method
Authors: Dong Yongjun , Xu Jun , Zhou Guoqing , Zhao Guangjun , Su Liangbi , Xu Xiaodong , Li Hongjun , Si JiLiang
Published: December 2006

Color centers in undoped YAP crystals induced by gamma‐irradiation were investigated by means of additional absorption spectra and thermal treatments. Color centers related to the 265 and 311 nm absorption bands were caused by Fe impurity ions and the charge state recharge of the Fe3+ and Fe2+ ions occurred during the gamma‐irradiation process. Gamma‐irradiation and air annealing affect the 400 nm AA (additional absorption) band intensity in an opposite way and (Vc––F+) defects should be responsible for this band. Further air and hydrogen annealing of un‐irradiated YAP shows that color centers at 193 nm may be associated with Vc defects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulations of nucleation of single‐walled carbon nanotubes
Authors: Luo Chenglin , Yu Hewu , Zhang Yiquan , Cai Linhui , He Xiangdong
Published: December 2006

A common nucleation and growth mechanism of single‐walled carbon nanotubes based on a vapour–liquid–solid model has been proposed according to molecular dynamics simulations and related experiments. This mechanism can explain many important experimental observations such as similarities between samples synthesized using different techniques, minimum and maximum radii of single‐walled carbon nanotubes and the fact that single‐walled carbon nanotubes can only grow within a certain temperature interval. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Valence and coordination of chromium ions in ZnO–Sb2O3–B2O3 glass system by means of spectroscopic and dielectric relaxation studies
Authors: Srinivasa Reddy M. , Prasad S. V. G. V. A. , Veeraiah N.
Published: December 2006

ZnO–Sb2O3–B2O3 glasses containing different concentrations of chromium ions (introduced as CrO2–4) ranging from 0 to 1.0 mol% were prepared. A number of studies viz., differential thermal analysis, infrared, optical absorption, Raman and ESR spectra and dielectric properties (constant ε ′, loss tan δ, a.c. conductivity σac over a wide range of frequency and temperature) of these glasses have been carried out. The results have been analyzed in the light of different oxidation states of chromium ions. The analysis indicates that when the concentration of chromium ions is ∼0.2 mol%, these ions mostly exist in Cr6+ state, occupy network forming positions with CrO2–4 structural units and increase the rigidity of the glass network. When the concentration of the chromium ions is increased beyond 0.2 mol%, these ions seem to be reduced from Cr6+ state to Cr5+ and Cr3+ states. A gradual transformation of chromium ions from tetrahedral positions to octahedral positions could also be established from these results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and infrared optical properties of evaporated erbium fluoride films
Authors: Su W. T. , Li B. , Liu D. Q. , Zhang F. S.
Published: December 2006

Erbium fluoride (ErF3) films were deposited on germanium substrate with different substrate temperatures. The films deposited at low substrate temperatures show amorphous structure, while those deposited at high substrate temperatures show polycrystalline structure with (002) preferred orientation. The roughness of the film increases from 0.47 nm for the amorphous film to tens of nanometres for the crystalline films deposited at high substrate temperatures. Furthermore, it has been found that the surface morphology of the crystalline ErF3 films is modulated by the tensile stress in thin films. The infrared optical constants of the films were determined by fitting the transmission spectrum in the wavelength range from 2 to 10 μm using the Lorentz oscillator model. Both the refractive indices and extinction coefficients decrease with increasing substrate temperature. The minimum refractive index and extinction coefficient of the ErF3 film at a wavelength of 10 μm is as low as n = 1.32 and k = 0.006, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High Q ‐factor NiCuZn ferrite with nanocrystalline ferrite particles and Co2O3 additives
Authors: Su Hua , Zhang Huaiwu , Tang Xiaoli , Liu Baoyuan , Jin Yulan
Published: December 2006

This work focuses on the effects of nanocrystalline ferrite particles (NFPs) on the sintering behaviour and magnetic properties of NiCuZn ferrite for multilayer chip inductor use. It was found that the NFPs could evidently improve the sintering behaviour of the ferrite because of their large surface free energy. Because the NFPs had the same chemical composition as the NiCuZn ferrite, samples with appropriate NFPs added could show better magnetic properties than samples with added Bi2O3. Also, to further increase the Q ‐factor of the NiCuZn ferrite, the effects of Co2O3 additive on the magnetic properties of the NFP‐added ferrite were studied. The results revealed that the permeability of the ferrite decreased monotonically due to added Co2O3; the Q ‐factor first increased and reached its peak with 0.2 wt% Co2O3 added, whereupon it began to decrease. With 30 wt% NFPs and 0.2 wt% Co2O3 additives, the NiCuZn ferrite showed a high Q ‐factor of more than 200. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recovery of dry etch‐induced damage of nano‐patterned GaN‐based light‐emitting diodes by rapid‐thermal‐annealing
Authors: Hong Hyun‐Gi , Kim S.‐S. , Kim D.‐Y. , Lee Takhee , Kim Kyoung‐Kook , Song June‐O. , Cho J. H. , Seong Tae‐Yeon
Published: December 2006

The effect of rapid‐thermal‐annealing on the performance of near‐UV GaN‐based light‐emitting diodes (LEDs) fabricated with nano‐patterned p‐type electrodes has been investigated. One‐dimensional (1‐D) nano‐patterns were formed on Cu‐doped indium oxide (CIO)/indium tin oxide (ITO) p‐electrode by sur‐ face relief grating and dry etching techniques. After the nano‐patterning, some of the samples are rapid‐thermal‐annealed at 530 and 630 °C in either air or nitrogen ambient. LEDs made with samples annealed 530 °C show much better electrical characteristics as compared to unannealed samples. In particular, LEDs with samples annealed 530 °C in air show higher output power (at 20 mA) and much reduced leakage current as compared to LEDs with unannealed samples. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magneto‐transport properties of NiMnSb thin films on InSb single crystals: Negative giant magnetoresistance
Authors: Gardelis S. , Androulakis J. , Viskadourakis Z. , Papadopoulou E. L. , Giapintzakis J. , Rai S. , Lodha G. S. , Roy S. B.
Published: December 2006

In this study we investigated the magneto‐transport properties of the ohmic contact between polycrystalline NiMnSb thin films grown by pulsed laser deposition and n‐type degenerate InSb (100) substrates. An unusual negative giant magnetoresistance (n‐GMR) effect is found when the external magnetic field is parallel to the in‐plane current direction. A similar effect is also observed when Ni films are deposited on InSb substrates. On the other hand, no n‐GMR effect is displayed when the deposited film is nonmagnetic. Grazing‐incidence X‐ray reflectometry shows the formation of a low‐density NiMnSb layer at the interface. The presence of such a layer coincides with the appearance of the n‐GMR.We argue that the n‐GMR effect is due to magnetic precipitates formed at the interface during the growth of the magnetic films. We propose that these precipitates align their magnetic moments in the direction of the external magnetic field and thus, the spin dependent scattering of the electrons is reduced. The effect of these precipitates on the magnetoresistance depends on the thermal processing of the system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of precipitates in Mn doped ZnO layers deposited by magnetron sputtering
Authors: Abouzaid M. , Ruterana P. , Liu C. , Morkoç H.
Published: December 2006

The precipitation of Mn rich phases in ZnO layers deposited by magnetron sputtering has been investigated as well as the precipitates influence on the magnetic properties. On top of sapphire (0001) substrates, the formation of Mn rich precipitates is observed following the deposition of Zn(Mn)O layers above 500 °C, the size of the precipitates is shown to increase with the Mn concentration. For Zn(Mn)O layers deposited on GaN in similar conditions, no precipitates have been seen to form, however the quality of layers highly improved when the temperature was brought down to 500 °C. At this optimal temperature, the measured magnetic properties are best in layers deposited on both substrates, such layers do not contain any of the observed Mn rich precipitates. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic investigation of the structural and electronic properties of ion implanted Mn–Ge alloys
Authors: Ottaviano L. , Passacantando M. , Verna A. , Parisse P. , Picozzi S. , Impellizzeri G. , Priolo F.
Published: December 2006

We review recent results of an extensive experimental study of ion implanted Mn–Ge(100) alloys fabricated by systematically varying the Mn dose (in the range 1–4 × 1016 at/cm2) and the Ge substrate temperature (from room temperature up to 300 °C) during the implantation. The samples have been investigated by means of X‐ray photoemission spectroscopy, scanning electron microscopy, transmission electron microscopy, electron energy loss spectroscopy, and scanning tunneling microscopy and spectroscopy. The combined investigation allows to determine, with an unprecedented deal of information at the nanometer scale, the morphological, structural, and electronic properties of such alloys. We evidence a porous to continuous transition in the surface morphology of the implanted layer when passing from 190 to 240 °C implantation substrate temperature. At higher implantation temperatures we directly demonstrate Mn dilution in the Ge matrix and also show the presence of extrinsic phases like Mn rich clusters. The presence of Mn rich precipitates is directly evidenced with transmission electron microscopy and corresponding energy loss Mn elemental maps taken at the Mn L3 edge. Larger clusters (with diameter greater that 10 nm) are in the Mn5Ge3 phase and are metallic, as demonstrated with scanning tunneling spectroscopy. Smaller clusters are still Mn rich but typically in an amorphous phase. These clusters are semiconducting with 0.45 eV energy gap. The results on the local electronic structure of the alloys investigated with scanning tunneling spectroscopy are also discussed in comparison with ab‐initio calculations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detection of sibutramine administration: a gas chromatography/mass spectrometry study of the main urinary metabolites
Authors: Strano‐Rossi Sabina , Colamonici Cristiana , Botrè Francesco
Published: December 2006

A gas chromatographic/mass spectrometric (GC/MS) study aimed at identifying the metabolites of sibutramine (1‐(4‐chlorophenyl)‐N,N‐dimethyl‐α‐(2‐methylpropyl)cyclobutanemethanamine) in urine is described. Urinary excretion of sibutramine metabolites following the oral administration of a single dose of sibutramine was followed by GC/MS analysis. After identification of the chromatographic signals corresponding to the six main urinary metabolites, the fragmentation pattern was studied in electron ionization (EI) mode after derivatization to the corresponding methyl and trimethylsilyl derivatives. Urine samples were pretreated according to a reference procedure (liquid/liquid separation, enzymatic hydrolysis, pre‐concentration under a stream of nitrogen and derivatization, either under thermal incubation and by microwave irradiation). All sibutramine metabolites were excreted as glucuroconjugates, and retain the chiral carbon present in the sibutramine skeleton. The metabolites identified included mono‐desmethylsibutramine (nor‐sibutramine), bi‐desmethylsibutramine (nor‐nor‐sibutramine), and the corresponding hydroxylated compounds, the hydroxylation taking place either on the cyclobutane or on the isopropyl chain. The excretion profiles of the different metabolites were also evaluated. From an analytical point of view, the method can be applied to different fields of forensic analytical toxicology, including anti‐doping analysis. Although the lack of certified reference materials does not allow a precise determination of the limits of detection (LODs) of all the sibutramine metabolites, an estimation taking into account the response factor of similar compounds ensures that all metabolites are still clearly detectable in a range of concentrations between 10 and 50 ng/mL, thus satisfying the minimum required performance limits (MRPLs) of the World Anti‐Doping Agency (WADA). Copyright © 2006 John Wiley & Sons, Ltd.
A gas‐inlet system coupled with a Knudsen cell mass spectrometer for high‐temperature studies
Authors: Brutti Sergio , Balducci Giovanni , Gigli Guido
Published: December 2006

A gas‐inlet system coupled with a Knudsen effusion mass spectrometer has been developed to study at high temperature the interaction of solids and vapors with reactive permanent gases, such as H2 and O2, directly introduced into the cell from external low‐pressure reservoirs (pressure range: 10−4 < p < 1 bar). By selecting the gas flow from the external reservoir the pressures of the gases inside the Knudsen cell can be quantitatively controlled over three orders of magnitude, approximately from 10−8 to 5·10−5 bar. Mixtures of two different gases can be introduced into the cell, controlling their partial pressures independently. The capabilities of the device have been tested with four gas‐solid systems: PbO(s) + O2(g), GeO2(s) + O2(g), Ga(s) + H2(g) and Au(s) + H2(g), by studying the relevant high‐temperature equilibria. The results obtained for the dissociation energies of the diatomic molecules PbO(g), GeO(g), GaH(g), and AuH(g) compare well with the literature data giving confidence in the reliability and versatility of the method. Preliminary experiments on the in situ formation of H2O(g) in the Knudsen cell by the introduction of controlled gaseous H2/O2 mixtures are also presented. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of the active and inactive metabolites of prasugrel in human plasma by liquid chromatography/tandem mass spectrometry
Authors: Farid Nagy A. , McIntosh Mary , Garofolo Fabio , Wong Ernest , Shwajch Amanda , Kennedy Monika , Young Michelle , Sarkar Pratibha , Kawabata Kiyoshi , Takahashi Makoto , Pang Henrianna
Published: December 2006

Two fast and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS)‐based bioanalytical assays were developed and validated to quantify the active and three inactive metabolites of prasugrel. Prasugrel is a novel thienopyridine prodrug that is metabolized to the pharmacologically active metabolite in addition to three inactive metabolites, which directly relate to the formation and elimination of the active metabolite. After extraction and separation, the analytes were detected and quantified using a triple quadrupole mass spectrometer using positive electrospray ionization. The validated concentration range for the inactive metabolites assay was from 1 to 500 ng/mL for each of the three analytes. Additionally, a 5× dilution factor was validated. The interday accuracy ranged from −10.5% to 12.5% and the precision ranged from 2.4% to 6.6% for all three analytes. All results showed accuracy and precision within ±20% at the lower limit of quantification and ±15% at other levels. The validated concentration range for the active metabolite assay was from 0.5 to 250 ng/mL. Additionally, a 10× dilution factor was validated. The interbatch accuracy ranged from −7.00% to 5.98%, while the precision ranged from 0.98% to 3.39%. Derivatization of the active metabolite in blood with 2‐bromo‐3'‐methoxyacetophenone immediately after collection was essential to ensure the stability of the metabolite during sample processing and storage. These methods have been applied to determine the concentrations of the active and inactive metabolites of prasugrel in human plasma. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative determination of isorhamnetin, quercetin and kaempferol in rat plasma by liquid chromatography with electrospray ionization tandem mass spectrometry and its application to the pharmacokinetic study of isorhamnetin
Authors: Lan Ke , Jiang Xuehua , He Jianling
Published: December 2006

A simple and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of quercetin, kaempferol and isorhamnetin in rat plasma. After being treated with β‐glucuronidase and sulfatase, the analytes were extracted by liquid/liquid extraction with the internal standard (IS; baicalein). The chromatographic separation was performed on a Diamonsil C18 column with a mobile phase consisting of 2% formic acid/methanol (10:90, v/v) at a flow rate of 1.00 mL/min, with a split of 200 µL to the mass spectrometer. Validation results indicated that the lower limit of quantification (LLOQ) was 1 ng · mL−1. The assay exhibited a linear range of 1–200 ng · mL−1 and gave a correlation coefficient of 0.9980 or better for each analyte. Quality control samples (1, 5, 20 and 100 ng · mL−1) in six replicates from each of three different runs demonstrated an intra‐assay precision (RSD) of 1.1–8.9%, an inter‐assay precision of 1.6–10.8%, and an overall accuracy (bias) of <13.4%. The extraction recovery of each analyte and internal standard was 70–80%. In the present study, we have investigated the pharmacokinetic profiles of isorhamnetin after oral application in rats equipped with a jugular catheter. After oral dosing of isorhamnetin, the mean values (n = 10) of Cmax were 57.8, 64.8 and 75.2 ng · mL−1 which were achieved at a Tmax of 8.0, 6.4 and 7.2 h for oral doses of 0.25, 0.5 and 1.0 mg · kg−1 body weight, respectively. The corresponding mean values for isorhamnetin area under the curver (AUC) from 0 to 60 h were 838.2, 1262.8, 1623.4 ng · h · mL−1. Our results further demonstrated that the samples analyzed showed isorhamnetin could not be transformed into quercetin or kaempferol in rats, indicating that the demethylation of the 3′‐oxymethyl group of isorhamnetin does not occur in Wistar rats. Copyright © 2006 John Wiley & Sons, Ltd.
Development of a liquid chromatography/electrospray ionization tandem mass spectrometric method for the determination of hydroxyl radical
Authors: Yang Fen , Zhang Ruiping , He Jiuming , Abliz Zeper
Published: December 2006

A rapid method combining liquid chromatography with electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) was developed for the determination of the hydroxyl radical (·OH). ·OH generated via Fenton reaction was spin‐trapped by 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) and then analyzed by LC/ESI‐MS/MS in multiple reaction monitoring (MRM) mode, using N‐methyl‐2‐pyrrolidone (NMP) as the internal standard. The peak area ratio of DMPO‐OH to NMP positively correlated with the concentration of ·OH. The relative standard deviation (RSD) of the method was 1.13% (n = 8). The present method was successfully applied to evaluate the ·OH scavenging capacity of several phenolic acids. Copyright © 2006 John Wiley & Sons, Ltd.
Screening and analysis of the multiple absorbed bioactive components and metabolites of Dangguibuxue decoction by the metabolic fingerprinting technique and liquid chromatography/diode‐array detection mass spectrometry
Authors: Wang Ping , Liang Yizeng , Zhou Neng , Chen Benmei , Yi Lunzhao , Yu Yan , Yi Zhibiao
Published: December 2006

Based on the metabolic fingerprinting technique and liquid chromatography/diode array detection mass spectrometry (LC/DAD‐MS), a method for rapid screening and analysis of the multiple absorbed bioactive components and metabolites of an oral solution of Dangguibuxue decoction (ODD) in rabbit plasma after oral administration of ODD was developed. The results obtained from a comprehensive comparative analysis of the fingerprints of the ODD and its metabolic fingerprints in rabbit plasma indicated that 46 components in the ODD were absorbed into the rabbit's body. Of them, ten components were tentatively identified from their MS and UV spectra and retention behaviors by comparing the results with the reported literature. They were calycosin‐7‐O‐β‐D‐glycoside, (6aR,‐11aR)‐hydroxy‐9,10‐dimethoxypterocarpan‐3‐O‐β‐D‐glycoside, ononin, L‐3‐hydroxy‐9,10‐dimethoxypterocarpan, formononetin, (3R)‐7,2'‐dihydroxy‐3',4'‐dimethoxyisoflavan, sedanenolide, E‐ligustilide, Z‐ligustilide, and Z‐butylidenephthalide. In addition, 21 components were only found in the metabolic fingerprints, which suggested that they might be metabolites of some components in the ODD. The findings demonstrated that the proposed method could be used to rapidly and simultaneously analyze and screen the multiple absorbed bioactive constituents and metabolites in a formula of traditional Chinese medicines (TCMs) by comparing and contrasting the chromatographic fingerprints with its metabolic fingerprints. This is very important not only for the pharmaceutical discovery process and the quality control of crude drugs, but also to explain the curative mechanism of TCMs. Copyright © 2006 John Wiley & Sons, Ltd.
Fourier transform mass spectrometry to monitor hyaluronan–protein interactions: use of hydrogen/deuterium amide exchange
Authors: Seyfried Nicholas T. , Atwood James A. , Yongye Austin , Almond Andrew , Day Anthony J. , Orlando Ron , Woods Robert J.
Published: December 2006

The use of Fourier transform mass spectrometry (FTMS) to monitor noncovalent complex formation in the gas phase under native conditions between the Link module from human tumor necrosis factor stimulated gene‐6 (Link_TSG6) and hyaluronan (HA) oligosaccharides is reported. In particular, a titration experiment with increasing concentrations of octasaccharide (HA8) to protein produced a noncovalent complex with 1:1 stoichiometry when the oligosaccharide was in molar excess. However, in the presence of a molar excess of tetrasaccharide (HA4) nearly all proteins and oligosaccharides were observed in their unbound charge states. These results are consistent with solution‐phase properties for this interaction in which HA8, but not HA4, supports high affinity Link_TSG6 binding. Hydrogen/deuterium amide exchange mass spectrometry (H/D‐EX MS) was also utilized to investigate the level of global deuterium incorporation, over time, for Link_TSG6 in both the absence and presence of HA8. After dilution into quenching conditions, deuterium incorporation reached limiting asymptotic values of 37 and 26 deuterons for the free and bound protein at 240 and 480 min, respectively, indicating that the oligosaccharide interferes with amide exchange on binding. To detect sequence‐specific deuterium incorporation, pepsin digestion of Link_TSG6 in both the absence and presence of HA8 was performed. A level of deuterium incorporation of 10–30% was observed for peptides analyzed in free Link_TSG6. Interestingly, HA8 blocked some sites of proteolysis in Link_TSG6 compared to the free protein. Molecular modeling indicated that amino acids proximal to the ligand correlated with regions of the protein that were resistant to enzymatic digestion. Of the peptides that could be analyzed by H/D‐EX MS in the presence of the ligand, a 30–60% reduction in deuterium incorporation, relative to the free protein, was observed, even for those sequences not directly involved in HA binding. These results support the utility of FTMS as a method for the characterization of protein–carbohydrate interactions. Copyright © 2006 John Wiley & Sons, Ltd.
Multiple oligomeric forms of Escherichia coli DnaB helicase revealed by electrospray ionisation mass spectrometry
Authors: Watt Stephen J. , Urathamakul Thitima , Schaeffer Patrick M. , Williams Neal K. , Sheil Margaret M. , Dixon Nicholas E. , Beck Jennifer L.
Published: December 2006

The Escherichia coli DnaB protein (DnaB6) is the hexameric helicase that unwinds genomic DNA so it can be copied by the DNA replication machinery. Loading of the helicase onto DNA requires interactions of DnaB6 with six molecules of its loading partner protein, DnaC. Nano‐electrospray ionisation mass spectrometry (nanoESI‐MS) of mutant proteins was used to examine the roles of the residues Phe102 (F102) and Asp82 (D82) in the N‐terminal domain of DnaB in the assembly of the hexamer. When the proteins were prepared in 1 M ammonium acetate containing magnesium and adenosine triphosphate (ATP) at pH 7.6, both hexameric and heptameric forms of wild‐type and F102W, F102E and D82N mutant DnaBs were observed in mass spectra. The spectra of the D82N mutant also showed substantial amounts of a decameric species and small amounts of a dodecamer. In contrast, the F102H DnaB mutant was incapable of forming oligomers of order higher than the hexamer. Thus, although Phe102 is not the only determinant of hexamer assembly, this residue has a role in oligomerisation. NanoESI mass spectra were obtained of mixtures of DnaB6 with DnaC. The DnaB6(DnaC)6 complex (calculated Mr 481 164) was observed only when the two proteins were present in equimolar amounts. The data are consistent with cooperative assembly of the complex. ESI mass spectra of mixtures containing DnaC and ATP showed that DnaC slowly hydrolysed ATP to ADP as indicated by ions corresponding to DnaC/ATP and DnaC/ADP complexes. These experiments show that E. coli DnaB can form a heptameric complex and that nanoESI‐MS can be used to probe assembly of large (>0.5 MDa) macromolecular complexes. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization of oxysterols by electrospray ionization tandem mass spectrometry after one‐step derivatization with dimethylglycine
Authors: Jiang Xuntian , Ory Daniel S. , Han Xianlin
Published: December 2006

We report a novel approach to derivatize the primary, secondary, and tertiary hydroxy group(s) of oxysterols with N,N‐dimethylglycine (DMG) in the presence of both 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide and 4‐(N,N‐dimethylamino)pyridine to yield their corresponding mono‐ or di‐DMG esters. Eight oxysterols including 7‐oxocholesterol, 5α,6α‐ and 5β,6β‐epoxycholesterols, as well as 7α‐, 7β‐, 24(S)‐, 25‐, and 27‐hydroxycholesterols, were studied. Electrospray ionization tandem mass spectrometric characterization of these singly or doubly protonated derivatives demonstrates the presence of an informative fragmentation pattern for each oxysterol derivative. Potential dissociation pathways for the production of these unique fragmentation patterns are proposed and discussed. Collectively, these informative and unique fragmentation patterns allow rapid and direct discrimination of the identities of 7α‐, 7β‐, 24(S)‐, 25‐, and 27‐hydroxycholesterol isomers, as well as 5α,6α‐ and 5β,6β‐epoxycholesterol isomers, thereby potentially providing a foundation for quantitative analysis of oxysterols in biological samples in combination with a chromatographic separation. Copyright © 2006 John Wiley & Sons, Ltd.
Mass spectrometric evidence for different complexes of peptides and proteins with arsenic(III), arsenic(V), copper(II), and zinc(II) species
Authors: Schmidt Anne‐Christine , Koppelt Jenny , Neustadt Madlen , Otto Matthias
Published: December 2006

Trivalent and pentavalent arsenic were incubated with sulfur‐containing amino acid, peptide and protein solutions both as organic compounds (phenylarsine oxide, phenylarsonic acid, dimethylarsinic acid, monomethylarsonic acid) and as inorganic compounds (arsenite, As(III), and arsenate, As(V)). After incubation of phenylarsine oxide solutions with cysteine and glutathione the mass spectra showed a covalent bond between arsenic and sulfur, which was stable at both acidic and neutral pH values. The mass spectra were dominated by monovalent ions at m/z 272 for cysteine samples and at m/z 458 for glutathione samples. Based on these masses the ionic structures could be ascribed to either fragment ions of the covalent arsenic‐sulfur complexes or to other arsenic‐bonding sites presumably at the amino group. Interestingly, under the same conditions no interactions of inorganic arsenite or arsenate could be measured. In the presence of added Cu2+ ions all mass signals caused by a reaction of phenylarsine oxide with glutathione disappeared. In these mass spectra only the oxidised form of glutathione (GSSG) was found because of the redox activity of Cu(II). For the model protein lysozyme, no interactions with arsenic could be detected, whereas definite Cu‐ and Zn‐lysozyme complexes with a stoichiometry of 1:1 and 2:1 for Zn2+ ions and Cu2+ ions, respectively, were observed. In contrast, for thioredoxin a bonding of As that depended on the concentration of the disulfide‐reducing agent tris(2‐carboxyethyl) phosphine was demonstrated.

For three different phenylarsonic acids and for dimethylarsinic acid that all contain pentavalent arsenic, complexes with glutathione appeared in the mass spectra, which can be attributed to non‐covalent interactions or to a covalent bond caused by an additive reaction.

The optimisation of the experimental conditions necessary for the mass spectrometric analysis of the interactions of the arsenic species with peptides and proteins is described and the obtained mass spectra that provide information on the kinds of bonds are discussed. Copyright © 2006 John Wiley & Sons, Ltd.