bluuebunny/crossref_metadata_2025 huggingface dataset:
Xanthurenic acid distribution, transport, accumulation and release in the rat brain
Authors: Gobaille Serge , Kemmel Véronique , Brumaru Daniel , Dugave Christophe , Aunis Dominique , Maitre Michel
Published: March 2008

Tryptophan metabolism through the kynurenine pathway leads to several neuroactive compounds, including kynurenic and picolinic acids. Xanthurenic acid (Xa) has been generally considered as a substance with no physiological role but possessing toxic and apoptotic properties. In the present work, we present several findings which support a physiological role for endogenous Xa in synaptic signalling in brain. This substance is present in micromolar amounts in most regions of the rat brain with a heterogeneous distribution. An active vesicular synaptic process inhibited by bafilomycin and nigericin accumulates xanthurenate into pre‐synaptic terminals. A neuronal transport, partially dependant on adenosine 5′‐triphosphate (ATP), sodium and chloride ions exists in NCB‐20 neurons which could participate in the clearance of extracellular xanthurenate. Both transports (neuronal and vesicular) are greatly enhanced by the presence of micromolar amounts of zinc ions. Finally, electrical in vivo stimulation of A10‐induced Xa release in the extracellular spaces of the rat prefrontal cortex. This phenomenon is reproduced by veratrine, K+ ions and blocked by EGTA and tetrodotoxin. These results strongly argue for a role for Xa in neurotransmission/neuromodulation in the rat brain, thus providing the existence of specific Xa receptors.
Sustained saturating level of glycine induces changes in NR2B‐containing‐NMDA receptor localization in the CA1 region of the hippocampus
Authors: Imamura Yukio , Ma Chun‐Lei , Pabba Mohan , Bergeron Richard
Published: March 2008

Post‐synaptic actions of glycine are terminated by specialized transporters. There are two genes encoding glycine transporters, GlyT1 and GlyT2. Glycine acts as a co‐agonist atN‐methyl‐d‐aspartate glutamatergic receptors (NMDARs). Blockage of GlyT1 enhances NMDAR function by controlling ambient glycine concentrations. Using whole‐cell patch‐clamp recordings of acute hippocampal slices, we investigated NMDAR kinetics of CA1 pyramidal neurons of mice expressing 50% of GlyT1 (GlyT1+/−). In this study, we report that the glycine modulatory site of the NMDAR at CA1 synapses is saturated in GlyT1+/− but not in wild‐type (WT) mice. We also found that the effect of ifenprodil, a highly selective NR2B‐containing‐NMDAR antagonist, is significantly reduced at CA1 synapses in GlyT1+/− compared to WT mice while immunoblotting experiments do not show significant differences for NR1, NR2A‐B‐C‐D subunits in both types of mice, suggesting alteration in NR2B‐containing‐NMDAR localization under a state of chronic saturating level of endogenous glycine. Using a pharmacological approach with MK‐801 and DL‐TBOA, we discriminated synapticvis‐à‐visextra‐synaptic NMDARs. We found that NR2B‐containing‐NMDARs are expressed at a higher level in the extra‐synaptic area of CA1 pyramidal neurons from GlyT1+/− compared to WT mice. Our results demonstrate that chronic saturating level of glycine induces significant changes in NMDAR localization and kinetic. Therefore, results from our study should help to gain a better understanding of the role of glycine in pathological conditions.
Characterization of signaling pathway for the translocation of neuronal nitric oxide synthase to the plasma membrane by PACAP
Authors: Ohnishi Takayuki , Okuda‐Ashitaka Emiko , Matsumura Shinji , Katano Tayo , Nishizawa Mikio , Ito Seiji
Published: March 2008

In the central nervous system, the activation of neuronal nitric oxide synthase (nNOS) is closely associated with activation of NMDA receptor, and trafficking of nNOS may be a prerequisite for efficient NO production at synapses. We recently demonstrated that pituitary adenylate cyclase activating polypeptide (PACAP) and NMDA synergistically caused the translocation of nNOS to the membrane and stimulated NO production in PC12 (pheochromocytoma) cells. However, the mechanisms responsible for trafficking and activation of nNOS are largely unknown. To address these issues, here we constructed a yellow fluorescent protein (YFP)‐tagged nNOS N‐terminal (1–299 a.a.) mutant, nNOSNT‐YFP, and visualized its translocation in PC12 cells stably expressing it. PACAP enhanced the translocation synergistically with NMDA in a time‐ and concentration‐dependent manner. The translocation was blocked by inhibitors of protein kinase A (PKA), protein kinase C (PKC), and Src kinase; and the effect of PACAP could be replaced with PKA and PKC activators. The β‐finger region in the PSD‐95/disc large/zonula occludens‐1 domain of nNOS was required for the translocation of nNOS and its interaction with post‐synaptic density‐95 (PSD‐95), and NO formation was attenuated by dominant negative nNOSNT‐YFP. These results demonstrate that PACAP stimulated nNOS translocation mediated by PKA and PKC via PAC1‐receptor (a PACAP receptor) and suggest cross‐talk between PACAP and NMDA for nNOS activation by Src‐dependent phosphorylation of NMDA receptors.
THE RELATIONSHIP BETWEEN LITHOLOGY, FLAKING PROPERTIES AND ARTEFACT MANUFACTURE FOR AUSTRALIAN SILCRETES*
Authors: WEBB J. A. , DOMANSKI M.
Published: March 2008

Mechanical properties of Australian silcrete strongly influenced raw material selection and artefact manufacture. Microcrystalline silcrete, with high compressive and tensile strength, is suitable for blade tools requiring fine retouch. Fine‐grained silcrete (high compressive strength but lower tensile strength) was often used for blade‐based implements, but is more susceptible to edge fracturing. Medium‐grained silcrete has poor flaking properties (low compressive and tensile strength) and was often used for flake manufacture. Thus material determinism can explain much of the variability in silcrete artefact morphology and assemblage composition. Silcrete compressive strength is positively correlated with percentage of microcrystalline matrix and negatively correlated with average grain size, so hand lens examination of a silcrete sample can give a good indication of its likely flaking quality.
Helicobacter pylori Genotyping and Sequencing Using Paraffin‐Embedded Biopsies from Residents of Colombian Areas with Contrasting Gastric Cancer Risks
Authors: Sicinschi Liviu A. , Correa Pelayo , Peek Richard M. , Camargo M. Constanza , Delgado Alberto , Piazuelo M. Blanca , Romero‐Gallo Judith , Bravo Luis E. , Schneider Barbara G.
Published: March 2008

Background:   cagA‐positive and vacA s1 and m1 genotypes of Helicobacter pylori are associated with an elevated risk of gastric cancer (GC). We determined these genotypes using paraffin‐embedded gastric biopsy specimens harvested from infected individuals and compared genotype distributions in two Colombian populations residing in geographic regions with a high and low incidence of GC.

Methods:   DNA from paraffin‐embedded gastric biopsies from 107 adults was amplified using primers specific for cagA, for the cag‘empty site’, for the s and m alleles of vacA, and for H. pylori 16S rRNA.

Results:   H. pylori infection was detected by molecular assays in 97 (90.7%) biopsies. Complete genotyping of cagA and vacA was achieved in 94 (96.9%) cases. The presence of cagA was detected in 78 of 97 cases (80.4%); when considered separately, cagA and vacA s regions were not significantly associated with a particular geographic area. The vacA m1 allele and s1m1 genotypes were more common in the area of high risk for GC (p = .037 and p = .044, respectively), while the vacA m2 allele and s2m2 genotypes were more prevalent in the low‐risk area. The prevalence of the combination of cagA‐positive, vacA s1m1 genotypes was 84.3% and 60.5% for high and low risk areas, respectively (p = .011).

Conclusions:  H. pylori cagA and vacA genotyping from paraffin‐embedded gastric biopsies permitted reliable typability and discrimination. The more virulent cagA‐positive s1m1 strains, as well as vacA m1 genotype, were more prevalent in high risk than in low risk areas, which may contribute to the difference in GC risk between those two regions.
Four Modes of Adhesion are Used During Helicobacter pylori Binding to Human Mucins in the Oral and Gastric Niches
Authors: Lindén Sara K. , Wickström Claes , Lindell Gert , Gilshenan Kristen , Carlstedt Ingemar
Published: March 2008

Background:  Helicobacter pylori causes peptic ulcer disease and gastric cancer, and the oral cavity is likely to serve as a reservoir for this pathogen. We investigated the binding of H. pylori to the mucins covering the mucosal surfaces in the niches along the oral to gastric infection route and during gastric disease and modeled the outcome of these interactions.

Materials and Methods:  A panel of seven H. pylori strains with defined binding properties was used to identify binding to human mucins from saliva, gastric juice, cardia, corpus, and antrum of healthy stomachs and of stomachs affected by gastritis at pH 7.4 and 3.0 using a microtiter‐based method.

Results:  H. pylori binding to mucins differed substantially with the anatomic site, mucin type, pH, gastritis status, and H. pylori strain all having effect on binding. Mucins from saliva and gastric juice displayed the most diverse binding patterns, involving four modes of H. pylori adhesion and the MUC5B, MUC7, and MUC5AC mucins as well as the salivary agglutinin. Binding occurred via the blood‐group antigen‐binding adhesin (BabA), the sialic acid‐binding adhesin (SabA), a charge/low pH‐dependent mechanism, and a novel saliva‐binding adhesin. In the healthy gastric mucus layer only BabA and acid/charge affect binding to the mucins, whereas in gastritis, the BabA/Leb‐dependent binding to MUC5AC remained, and SabA and low pH binding increased.

Conclusions:  The four H. pylori adhesion modes binding to mucins are likely to play different roles during colonization of the oral to gastric niches and during long‐term infection.
Leptin Receptor Signaling is Required for Vaccine‐Induced Protection Against Helicobacter pylori
Authors: Wehrens Andrea , Aebischer Toni , Meyer Thomas F. , Walduck Anna K.
Published: March 2008

Background:  A vaccine against Helicobacter pylori would be a desirable alternative to antibiotic therapy. Vaccination has been shown to be effective in animal models but the mechanism of protection is poorly understood. Previous studies investigating the gene expression in stomachs of vaccinated mice showed changes in adipokine expression correlated to a protective response. In this study, we investigate a well‐characterized adipokine‐leptin, and reveal an important role for leptin receptor signaling in vaccine‐induced protection.

Materials and Methods:  Leptin receptor signaling‐deficient (C57BL/Ks Leprdb), wild‐type C57BL/Ks m littermates and C57BL/6 mice were vaccinated, and then challenged with H. pylori. Levels of bacterial colonization, antibody levels, and gastric infiltrates were compared. The local gene expression pattern in the stomach of leptin receptor signaling‐deficient and wild‐type mice was also compared using microarrays.

Results:  Interestingly, while vaccinated wild‐type lean C57BL/6 and C57BL/Ks m mice were able to significantly reduce colonization compared to controls, vaccinated obese C57BL/Ks Leprdb were not. All mice responded to vaccination, i.e. developed infiltrates predominantly of T lymphocytes in the gastric mucosa, and made H. pylori‐specific antibodies. A comparison of expression profiles in protected C57BL/6 and nonprotected C57BL/Ks Leprdb mice revealed a subset of inflammation‐related genes that were more strongly expressed in nonprotected mice.

Conclusions:  Our data suggest that functional leptin receptor signaling is required for mediating an effective protective response against H. pylori.
Associations Between Vitamin D Status and Pain in Older Adults: The Invecchiare in Chianti Study
Authors: Hicks Gregory E. , Shardell Michelle , Miller Ram R. , Bandinelli Stefania , Guralnik Jack , Cherubini Antonio , Lauretani Fulvio , Ferrucci Luigi
Published: March 2008

OBJECTIVES: To examine cross‐sectional associations between vitamin D status and musculoskeletal pain and whether they differ by sex.

DESIGN: Population‐based study of persons living in the Chianti geographic area (Tuscany, Italy).

SETTING: Community.

PARTICIPANTS: Nine hundred fifty‐eight persons (aged ≥65) selected from city registries of Greve and Bagno a Ripoli.

MEASUREMENTS: Pain was categorized as mild or no pain in the lower extremities and back; moderate to severe back pain, no lower extremity pain; moderate to severe lower extremity pain, no back pain; and moderate to severe lower extremity and back pain (dual region). Vitamin D was measured according to radioimmunoassay, and deficiency was defined as 25‐hydroxyvitamin D (25(OH)D) less than 25 nmol/L.

RESULTS: The mean age±standard deviation was 75.1±7.3 for women and 73.9±6.8 for men. Fifty‐eight percent of women had at least moderate pain in some location, compared with 27% of men. After adjusting for potential confounders, vitamin D deficiency was not associated with lower extremity pain or dual‐region pain, although it was associated with a significantly higher prevalence of at least moderate back pain without lower extremity pain in women (odds ratio=1.96, 95% confidence interval=1.01–3.59) but not in men.

CONCLUSION: Lower concentrations of 25(OH)D are associated with significant back pain in older women but not men. Because vitamin D deficiency and chronic pain are fairly prevalent in older adults, these findings suggest it may be worthwhile to query older adults about their pain and screen older women with significant back pain for vitamin D deficiency.
Do Financial Incentives of Introducing Case Mix Reimbursement Increase Feeding Tube Use in Nursing Home Residents?
Authors: Teno Joan M. , Feng Zhanlian , Mitchell Susan L. , Kuo Sylvia , Intrator Orna , Mor Vincent
Published: March 2008

OBJECTIVES: To determine whether adoption of Medicaid case mix reimbursement is associated with greater prevalence of feeding tube use in nursing home (NH) residents.

DESIGN: Secondary analysis of longitudinal administrative data about the prevalence of feeding tube insertion and surveys of states' adoption of case mix reimbursement.

SETTING: NHs in the United States.

PARTICIPANTS: NH residents at the time of NH inspection between 1993 and 2004.

MEASUREMENTS: Facility prevalence of feeding tubes reported at the state inspection of NHs reported in the Online Survey, Certification and Reporting database and interviews with state policy makers regarding the adoption of case mix reimbursement.

RESULTS: Between 1993 and 2004, 16 states adopted Resource Utilization Group case mix reimbursement. States varied in the prevalence of feeding tubes in their NHs. Although the use of feeding tube increased substantially over the years of the study, once temporal trends and facility fixed effects were accounted for, case mix reimbursement was not associated with greater prevalence of feeding tube use.

CONCLUSION: The adoption of Medicaid case mix reimbursement was not associated with an increase in the prevalence of feeding tube use.
A Nonparametric Mean Estimator for Judgment Poststratified Data
Authors: Wang Xinlei , Lim Johan , Stokes Lynne
Published: March 2008

Summary MacEachern, Stasny, and Wolfe (2004, Biometrics60, 207–215) introduced a data collection method, called judgment poststratification (JPS), based on ideas similar to those in ranked set sampling, and proposed methods for mean estimation from JPS samples. In this article, we propose an improvement to their methods, which exploits the fact that the distributions of the judgment poststrata are often stochastically ordered, so as to form a mean estimator using isotonized sample means of the poststrata. This new estimator is strongly consistent with similar asymptotic properties to those in MacEachern et al. (2004). It is shown to be more efficient for small sample sizes, which appears to be attractive in applications requiring cost efficiency. Further, we extend our method to JPS samples with imprecise ranking or multiple rankers. The performance of the proposed estimators is examined on three data examples through simulation.
An Enhanced Quantile Approach for Assessing Differential Gene Expressions
Authors: Wang Huixia , He Xuming
Published: March 2008

Summary Due to the small number of replicates in typical gene microarray experiments, the performance of statistical inference is often unsatisfactory without some form of information‐sharing across genes. In this article, we propose an enhanced quantile rank score test (EQRS) for detecting differential expression in GeneChip studies by analyzing the quantiles of gene intensity distributions through probe‐level measurements. A measure of sign correlation, δ, plays an important role in the rank score tests. By sharing information across genes, we develop a calibrated estimate of δ, which reduces the variability at small sample sizes. We compare the EQRS test with four other approaches for determining differential expression: the gene‐specific quantile rank score test, the quantile rank score test assuming a common δ, a modified t‐test using summarized probe‐set‐level intensities, and the Mack–Skillings rank test on probe‐level data. The proposed EQRS is shown to be favorable for preserving false discovery rates and for being robust against outlying arrays. In addition, we demonstrate the merits of the proposed approach using a GeneChip study comparing gene expression in the livers of mice exposed to chronic intermittent hypoxia and of those exposed to intermittent room air.
Combining Multiple Biomarker Models in Logistic Regression
Authors: Yuan Zheng , Ghosh Debashis
Published: March 2008

Summary In medical research, there is great interest in developing methods for combining biomarkers. We argue that selection of markers should also be considered in the process. Traditional model/variable selection procedures ignore the underlying uncertainty after model selection. In this work, we propose a novel model‐combining algorithm for classification in biomarker studies. It works by considering weighted combinations of various logistic regression models; five different weighting schemes are considered in the article. The weights and algorithm are justified using decision theory and risk‐bound results. Simulation studies are performed to assess the finite‐sample properties of the proposed model‐combining method. It is illustrated with an application to data from an immunohistochemical study in prostate cancer.
Generalized Maximally Selected Statistics
Authors: Hothorn Torsten , Zeileis Achim
Published: March 2008

Summary Maximally selected statistics for the estimation of simple cutpoint models are embedded into a generalized conceptual framework based on conditional inference procedures. This powerful framework contains most of the published procedures in this area as special cases, such as maximally selected χ2 and rank statistics, but also allows for direct construction of new test procedures for less standard test problems. As an application, a novel maximally selected rank statistic is derived from this framework for a censored response partitioned with respect to two ordered categorical covariates and potential interactions. This new test is employed to search for a high‐risk group of rectal cancer patients treated with a neo‐adjuvant chemoradiotherapy. Moreover, a new efficient algorithm for the evaluation of the asymptotic distribution for a large class of maximally selected statistics is given enabling the fast evaluation of a large number of cutpoints.
Processing and Characterization of Multiphase Ceramic Composites Part I: Duplex Composites FormedIn Situfrom Solution
Authors: Kim Dong‐Kyu , Kriven Waltraud M.
Published: March 2008

Chemically compatible 50 vol% Al2O3–50 vol% YAG (yttrium aluminum garnet, Y3Al5O12), 50 vol% Al2O3–50 vol% mullite, and 50 vol% Al2O3–50 vol% NiAl2O4,in situ, duplex composite powders were fabricated by a chemical synthesis method. Both amorphous and crystalline powders were synthesized. The physical and mechanical properties of YAG andin situ, solution derived composites made using these powders were analyzed. Mechanically mixed, composite powders were made by a conventional, ball‐milling technique. The properties of the composites made fromin situversus mechanically mixed powders were studied. Compared with pellets made from crystalline powder, amorphous powder‐derived pellets had about a twofold higher sintering shrinkage. The crystalline powder‐derived YAG pellet sintered at 1650°C for 10 h had a three‐point bending strength of 244±3 MPa. A 50 vol% Al2O3–50 vol% YAGin situcomposite achieved an average bending strength of 361±19 MPa after sintering at 1700°C for 5 h. Grain size measurements indicated a mutual grain growth retardation effect of alumina and YAG phases in the composites. The better properties ofin situcomposites compared with mechanically mixed composites were attributed to the intimate mixing, at a molecular level, during the processing ofin situcomposites. The possible formation of a glassy phase in the Al2O3‐mullitein situcomposite heat treated at higher temperatures was discussed. The physical and mechanical properties of alumina–mullite and Al2O3–NiAl2O4in situcomposites were investigated.
Enthalpy and Anisotropy Relaxation of Glass Fibers
Authors: Ya Min , Deubener Joachim , Yue Yuanzheng
Published: March 2008

Optical birefringence and calorimetric studies have been conducted with respect to structural relaxation of E‐glass (a type of calcium–alumosilicate glass system) fibers. Upon fiber drawing, the liquid of E‐glass is thermally hyperquenched and mechanically stretched. Hyperquenching (cooling rate >106 K/min) leads to higher enthalpy state of liquids, and thereby, to a higher fictive temperature than normal quenching (20 K/min), whereas stretching results in structural anisotropy of glasses, i.e., a certain degree of preferred structural orientation (stretched network) along the axial direction of the fibers, which is quantified by the optical birefringence. Simultaneous relaxation of both anisotropy and excess enthalpy (relative to the enthalpy of a glass cooled at the standard rate of 20 K/min) upon static annealing and dynamic heating is observed, both of which can be described using the Kohlrausch function. However, there is a striking difference between the birefringence and the excess enthalpy relaxations. The birefringence decays much faster than does the excess enthalpy during annealing. These observations imply that the birefringence decay results from fast relaxation of the local structure, while the enthalpy relaxation results from slow relaxation of larger domains of the network.
A Personal Account of Developments in Enthalpy Relaxation: A Tribute to C. T. Moynihan
Authors: Hodge Ian M.
Published: March 2008

The contributions of Connie Moynihan to the science of enthalpy relaxation are reviewed. The author's professional involvement with Moynihan's science is outlined, and the origins of a number of seminal developments are described. Developments of Moynihan's many and varied seminal contributions are described.
Microstructural Evolution in Some Silicate Glass–Ceramics: A Review
Authors: Pinckney Linda R. , Beall George H.
Published: March 2008

Just as the microstructures in glass–ceramics encompass the range from nanocrystalline transparent materials to microcrystalline tough materials, so the paths of microstructural evolution in glass–ceramics vary widely. Evolution can proceed in numerous ways, their genesis being a perturbation of some type, including the surface nucleation used in glass frit processing, crystallization of the primary phase or phases upon distinct crystalline nuclei, and nucleation promoted by nano‐ or microscale amorphous phase separation in the parent glass. Examples of the crystallization history of several glass–ceramic materials are described, with emphasis on how their microstructural evolution influences their ultimate physical and optical properties.
Formation of Hexagonal Metastable Phases from an Undercooled LuFeO3 Melt in an Atmosphere with Low Oxygen Partial Pressure
Authors: Vijaya Kumar M. S. , Nagashio Kosuke , Hibiya Taketoshi , Kuribayashi Kazuhiko
Published: March 2008

Controlling the oxygen partial pressure (PO2) in the ambient atmosphere is an important parameter for material processing because the transition metal ion changes its valence depending on PO2. In the present study, containerless solidification of the LuFeO3 melt, where the undercooling level can be treated as another experimental parameter, was carried out in order to explore the unidentified metastable phases under the controlled PO2 using an aerodynamic levitator. Decreasing PO2 down to 1 × 103 Pa, the unidentified phase was solidified from the undercooled melt. The X‐ray diffractometry results after annealing at 1 × 103 Pa showed the peak profile of the stable perovskite LuFeO3 phase, suggesting that this unidentified phase was thermodynamically metastable. Thermogravimetric analysis showed that the mass of the sample solidified at PO2= 1 × 103 Pa significantly increased, suggesting that the formation of the metastable phases might be related to the presence of Fe2+ ions.
Atomic Layer Deposition on Bulk Quantities of Surfactant‐Modified Single‐Walled Carbon Nanotubes
Authors: Zhan Guo‐Dong , Du Xiaohua , King David M. , Hakim Luis F. , Liang Xinhua , McCormick Jarod A. , Weimer Alan W.
Published: March 2008

Atomic layer deposition (ALD) on single‐walled carbon nanotubes (SWNTs) can be achieved through physical surface modification using liquid‐phase pretreatment dispersion techniques. Al2O3 ALD on nonfunctionalized SWNTs produced isolated nodule growth. Ethanol and sodium dodecylsulfate (SDS) pretreatment methods were utilized to disperse and functionalize batches of nanotube powders. Ethanol‐based dispersion techniques provided hydroxylated surfaces that promoted continuous Al2O3 films on SWNT surfaces. The SDS method provided a dense nucleation site pattern that allowed for conformal Al2O3 film growth. Al2O3 ALD processes yielded growth rates of 0.13 nm/cycle, independent of the functionalization technique, at 450 K. X‐ray photoelectron spectroscopy was used to quantify the composition of the films, which were amorphous as deposited. A surfactant‐assisted ALD mechanism is proposed, which retains a physisorbed micelle structure as a template for the dense precursor nucleation site pattern. Liquid‐phase pretreatment was found to be an efficient mechanism to overcome attractive forces associated with nanoscale particle systems, and significantly reduced the size of nanotube bundles. The successful ALD on an individual suspended nanotube in other work was extended to the bulk coating of SWNT powders. This work demonstrates significant progress toward the goal of producing commercially viable SWNT‐based nanocomposite devices that incorporate bulk quantities of ALD‐functionalized nanotubes.
Sintering and Crystallization of CaO–Al2O3–ZrO2–SiO2 Glasses Containing Different Amount of Al2O3
Authors: Siligardi Cristina , Lusvarghi Luca , Montorsi Monia , Vernia Cecilia
Published: March 2008

In this work several complementary techniques have been employed to carefully characterize the sintering and crystallization behavior of CaO–Al2O3–ZrO2–SiO2 glass powder compacts after different heat treatments. The research started from a new base glass 33.69 CaO–1.00 Al2O3–7.68 ZrO2–55.43SiO2 (mol%) to which 5 and 10 mol% Al2O3 were added. The glasses with higher amounts of alumina sintered at higher temperatures (953°C [lower amount] vs. 987°C [higher amount]). A combination of the linear shrinkage and viscosity data allowed to easily find the viscosity values corresponding to the beginning and the end of the sintering process. Anorthite and wollastonite crystals formed in the sintered samples, especially at lower temperatures. At higher temperatures, a new crystalline phase containing ZrO2 (2CaO·4SiO2·ZrO2) appeared in all studied specimens.
Dense TiO2 Coating Using the Solution Precursor Plasma Spray Process
Authors: Chen Dianying , Jordan Eric H. , Gell Maurice , Ma Xinqing
Published: March 2008

A dense titania (TiO2) coating was deposited from an ethanol solution containing titanium isopropoxide using the solution precursor plasma spray process. Thermal and crystallization behaviors of the solution precursor were investigated by thermal gravimetric analysis–differential thermal analysis, Fourier‐transform infrared spectrum, and X‐ray diffraction (XRD). XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. Scanning electron micrographs show the as‐sprayed coating is dense with uniform thickness and there are no coarse splat boundaries. The individual ultrafine splats (1–5 μm diameter) are composed of columnar grains. X‐ray photoelectron spectroscopy analysis indicates that some Ti–OH groups exist in the as‐sprayed coating surface. Deposition mechanisms are described based on model experiments.
Interface Character Distributions in WC–Co Composites
Authors: Kim Chang‐Soo , Massa Ted R. , Rohrer Gregory S.
Published: March 2008

The geometric and crystallographic characteristics of interfaces in WC–Co composites with a range of grain sizes and carbide volume fractions have been comprehensively characterized. The carbide crystals are most frequently terminated by (0001) and

surfaces. The average number of carbide vertices per grain and the basal‐to‐prismatic face area ratio of the WC–Co interfaces increase with the carbide volume fraction. The three most frequently occurring WC/WC grain boundaries are 90° twist boundaries about
, 30° twist boundaries about [0001], and asymmetric 90° boundaries about. The boundary populations do not vary with grain size or carbide volume fraction, suggesting that they are determined by the grain boundary energy anisotropy.
Atomic‐Scale Characterization of Barium Titanate Powders Formed by the Hydrothermal Process
Authors: Zhu Xinhua , Wang Junyi , Zhang Zhenghai , Zhu Jianmin , Zhou Shunhua , Liu Zhiguo , Ming Naiben
Published: March 2008

Nanocrystalline barium titanate (BaTiO3, BT) was synthesized hydrothermally at 220°C by reacting barium hydroxide with titanium dioxide. The resulting BT nanopowders were characterized by X‐ray diffraction (XRD), selected area electron diffraction (SAED), Raman spectrum, scanning electron microscopy (SEM), and high‐resolution transmission electron microscopy (HR‐TEM). The BT nanopowders have a cubic phase as revealed by the XRD and SAED results, whereas the Raman spectrum indicates that tetragonal phase BT exists in the produced nanopowders but is not the dominant phase because of the weak characteristic peak of the tetragonal structure at 305 cm−1. In the SEM and TEM images, many coarse‐faceted cubic nanoparticles and a small amount of spherical particles are observed, indicating a developed bimodal size distribution of the BT powders. The variations of electron diffraction contrast across these particles in the TEM images indicate the presence of high strain in the BT nanoparticles, which is probably caused by the lattice defects like OH− ions and their compensation by cation vacancies. The HR‐TEM image of a BT nanoparticle with a size of 24 nm and a spherical morphology demonstrates a uniform and perfect crystal structure. The surrounding edges of the particle are very smooth and no surface steps are observed. However, a terrace–ledge–kink (TLK) surface structure was frequently observed at the edges of the BT nanoparticles with rough surface morphology, and in most cases the terrace and ledge lie on the {100} planes. The observed TLK surface structure can be well interpreted by the theory of periodic bond chains. Small nucleated and triangular BT islands with three to four atomic layer thickness, and their outside surfaces faceted as (100) and (010) planes, are also observed in these particles. The rarely seen {110} surface in the BT nanoparticles was found to be reconstructed so that the surface was composed of corners bound by {100} minifaces like the triangular small islands. Microstructural defects such as antiphase boundaries were also observed near the edge of a BT nanoparticle, which were formed by the intersection of two crystalline parts with displacement deviation from each other by
, as revealed by the HR‐TEM images.
Thermochemical Reactions Between PZT and Ag/Pd Powders: Relevance to Cofiring of Multilayer Actuators
Authors: Donnelly Niall J. , Shrout Thomas R. , Randall Clive A. , Reaney Ian M.
Published: March 2008

Mixtures of Ag1−xPdx (x=0.2, 0.3) and doped PZT ceramic powders have been heat treated in air and the resulting phase content has been analyzed by X‐ray diffraction and transmission electron microscopy. Beginning around 400°C, a phase similar to PbPdO2 is formed on the surface of the Ag1−xPdx particles and subsequently decomposes at temperatures <700°C. Consequently, the remaining Ag1−xPdx powder becomes significantly silver‐rich while the reaction progresses. After decomposition the Pd appears to realloy and the initial Ag1−xPdx composition is recovered. We show that the reaction is all but eliminated in a nitrogen atmosphere. The occurrence of this reaction was also investigated in PZT multilayer actuators cofired with Ag0.7Pd0.3 electrodes. Transmission electron microscope analysis revealed the presence of distinct crystallites at the electrode–ceramic interface, most likely nucleated from a PbO liquid phase arising from the decomposition of PbPdO2.
Processing of ZrC–Mo Cermets for High Temperature Applications, Part II: Pressureless Sintering and Mechanical Properties
Authors: Landwehr Sean E. , Hilmas Gregory E. , Fahrenholtz William G. , Talmy Inna G.
Published: March 2008

Pressureless sintering of ZrC–Mo cermets was investigated in a He/H2 atmosphere and under vacuum. A large density increase was observed for specimens with >20 vol% Mo after heating at 2150°C for 60 min in a He/H2 atmosphere. The increase in density was attributed to the formation of Mo2C during heating and its subsequent eutectic reaction with Mo, which produced rounded ZrC grains in a Mo–Mo2C matrix. Sintering in vacuum did not produce the same increase in density, due to the lack of Mo2C formation and subsequent lack of liquid formation, which resulted in a microstructure with irregular ZrC grains with isolated areas of Mo. Mechanical properties testing showed a decrease in Young's modulus with increasing Mo content that was consistent with the models presented. Flexure strength of ZrC–Mo cermets sintered in He/H2 atmosphere materials increased with increasing Mo content from 320 MPa at 20 vol% Mo to 410 MPa at 40 vol% Mo. Strength was predicted by adapting theories developed previously for WC–Co cermets.
High‐Temperature Proton‐Conducting Lanthanum Ortho‐Niobate‐Based Materials. Part II: Sintering Properties and Solubility of Alkaline Earth Oxides
Authors: Mokkelbost Tommy , Kaus Ingeborg , Haugsrud Reidar , Norby Truls , Grande Tor , Einarsrud Mari‐Ann
Published: March 2008

The sintering properties and microstructure of La1−xAxNbO4 powders (x=0, 0.005, and 0.02 and A=Ca, Sr, and Ba), prepared by spray pyrolysis have been investigated. Dense materials (>97%) were obtained by conventional sintering at 1200°C and by hot pressing (25 MPa) at 1050°C, respectively. Homogeneous materials were obtained and the average grain size obtained by the two densification methods was ∼2.0 and ∼0.4 μm, respectively, for the 2% doped materials. Pure lanthanum ortho‐niobate (LaNbO4) showed a higher degree of grain growth. In the acceptor‐doped materials, secondary phases were observed to inhibit grain growth at 1200°C. At 1400°C or higher, molten secondary phases in the Ba‐doped materials resulted in severe grain growth, causing microcracking during cooling due to crystallographic anisotropy. A low solubility of AO (A=Ca, Sr, and Ba) in LaNbO4 is inferred from the presence of secondary phases, and 1 mol% solubility of SrO in LaNbO4 was found by electron microprobe analysis. The electrical conductivity in wet hydrogen of the materials demonstrated that the main charge carrier was protons up to 1000°C and reached a maximum value of ∼8·10−4 S/cm at 900°C.
Refractive Index Drop Observed After Precision Molding of Optical Elements: A Quantitative Understanding Based on the Tool–Narayanaswamy–Moynihan Model
Authors: Fotheringham Ulrich , Baltes Andrea , Fischer Peter , Höhn Petra , Jedamzik Ralf , Schenk Christian , Stolz Claudia , Westenberger Gerhard
Published: March 2008

The room‐temperature refractive index is measured for three different prior cooling rates (approximately 10, 50, and 250 K/h) for two glasses especially developed for precision molding. The empirical logarithmic relationship between the cooling rate and the refractive index is also reproduced for the comparatively high cooling rate of ca. 250 K/h. The same relationship is found in a simulation of these cooling rates by the semiempirical Tool–Narayanaswamy–Moynihan model for structural relaxation, with the necessary parameters obtained from differential scanning calorimetry and temperature jump experiments. The measured and the simulated refractive indices coincide within the limits of experimental error. The results demonstrate that the index drop, which is observed when these glasses are first cooled at a regular optical cooling rate (e.g., 2 K/h), and then precision molded (typical cooling rate 1000 K/h), can be understood considering the concepts of structural relaxation.
Immunohistochemical, tomographic and histological study on onlay iliac grafts remodeling
Authors: Faria Paulo E. P. , Okamoto Roberta , Bonilha‐Neto Ricardo M. , Xavier Samuel P. , Santos Antonio C. , Salata Luiz A.
Published: March 2008

Abstract: The information concerning the molecular events taking place in onlay bone grafts are still incipient. The objective of the present study is to correlate the effects of perforation of resident bone bed on (1) the timing of onlay autogenous graft revascularization; (2) the maintenance of volume/density of the graft (assessed through tomography); and (3) the occurrence of bone remodeling proteins (using immunohistochemistry technique) delivered in the graft. Thirty‐six New Zealand White rabbits were subjected to iliac crest onlay bone grafting on both sides of the mandible. The bone bed was drill‐perforated on one side aiming at accelerating revascularization, whereas on the other side it was kept intact. After grafts fixation and flaps suture all animals were submitted to tomography on both mandible sites. Six animals were sacrificed, respectively, at 3, 5, 7, 10, 20 and 60 days after surgery. A second tomography was taken just before sacrifice. Histological slides were prepared from each grafted site for both immunohistochemistry analysis [osteopontin, osteocalcin, type I collagen and vascular endothelial growth factor (VEGF) anti‐bodies] and histometric analysis. The values on bone volume measured on tomography showed no statistic significance (P≥0.05) between perforated and intact sites. Grafts placed on perforated beds showed higher bone density values compared with non‐perforated ones at 3 days (P≤0.05). This correlation was inverted at 60 days postoperatively. The findings from VEGF labeling revealed a tendency for earlier revascularization in the perforated group. The early revascularization of bone grafts accelerated the bone remodeling process (osteocalcin, type I collagen and osteopontin) that led to an increased bone deposition at 10 days. The extended osteoblast differentiation process at intermediate stages in the perforated group cooperated for a denser bone at 60 days.
Immunohistochemical characterization of guided bone regeneration at a dehiscence‐type defect using different barrier membranes: an experimental study in dogs
Authors: Schwarz Frank , Rothamel Daniel , Herten Monika , Wüstefeld Martin , Sager Martin , Ferrari Daniel , Becker Jürgen
Published: March 2008

Objectives: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes.

Material and methods: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen‐coated bone grafting material (BOC) in combination with either a native, three cross‐linked, a titanium‐reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin – OC, transglutaminase II – angiogenesis) and histomorphometrical analysis [e.g., bone‐to‐implant contact (BIC), area of new bone fill (BF)].

Results: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10–12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group.

Conclusion: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.
Peripheral blood cytogenetic studies in hematological neoplasms: predictors of obtaining metaphases for analysis
Authors: Hussein Kebede , Ketterling Rhett P. , Hulshizer Rachael L. , Kuffel Daniel G. , Wiktor Anne E. , Hanson Curtis A. , Tefferi Ayalew , Van Dyke Daniel L.
Published: March 2008

Peripheral blood (PB) is sometimes used in place of bone marrow (BM) for cytogenetic studies during the evaluation of hematologic malignancies. A total of 242 PB cytogenetic studies from adult patients were performed: clinical diagnosis was a myeloid neoplasm in 169 patients (70%), lymphoid or plasma cell neoplasm in 50 (21%), and a benign/reactive cytopenia or leukocytosis in 23 (9%). PB cytogenetic studies resulted in at least two analyzable metaphases in 142 of the 242 study cases (59%); in univariate analysis, this was predicted by the specific clinical diagnosis (P < 0.0001), presence and degree of circulating myeloid progenitor cells or blasts of any lineage (P < 0.0001), higher leukocyte count (P < 0.001), lower platelet count (P = 0.003), lower hemoglobin level (P = 0.002), and presence of palpable splenomegaly (P = 0.002). In multivariable analysis, only the presence of circulating myeloid progenitor cells or blasts sustained significance and this was consistent with the high yield rates seen in primary myelofibrosis (PMF) (80%), post‐PV/ET PMF (85%), acute myeloid leukemia (76%), and acute lymphoblastic leukemia (80%) in contrast with the low rates seen in ET (0%) and PV (2%). In 104 cases, BM cytogenetic studies were performed within 1 month of the PB cytogenetic studies; an abnormal BM cytogenetic finding was another independent predictor of a successful PB study (P = 0.002). PB cytogenetic studies are most appropriate in diseases of adults characterized by presence of circulating myeloid progenitors or blasts; the yield otherwise is too small to be cost‐effective.
Pilot experience with continuous infusion alemtuzumab in patients with fludarabine‐refractory chronic lymphocytic leukemia
Authors: Ferrajoli Alessandra , Wierda William G. , LaPushin Ruth , O’Brien Susan M. , Faderl Stefan , Browning Mary L. , Keating Michael J.
Published: March 2008

We evaluated the activity and tolerability of alemtuzumab given as a continuous infusion for 7 d followed by subcutaneous administration for 11 wk as salvage therapy for 10 patients with fludarabine‐refractory chronic lymphocytic leukemia. The continuous infusion of alemtuzumab was well tolerated. The typical infusion reaction seen with intravenous alemtuzumab was abolished. Two patients achieved a partial response with an overall response rate of 20%. Alemtuzumab levels were measured in four patients and detectable levels were obtained in three. Clinical activity needs to be confirmed in a larger patient population.
A novel mutation in a Turkish patient with Hermansky–Pudlak syndrome type 5
Authors: Korswagen Lindy‐Anne , Huizing Marjan , Simsek Suat , Janssen Jeroen J.W.M. , Zweegman Sonja
Published: March 2008

The Hermansky–Pudlak syndrome (HPS) is a rare genetically heterogeneous autosomal recessive disorder, characterized by tyrosinase‐positive oculocutaneous albinism, platelet dysfunction and lysosomal ceroid lipofuscin storage. This is caused by defects in lysosome‐related organelles. In humans eight different types of the syndrome are known, of which a short overview is given. The clinical features and a novel mutation of a patient with HPS type 5 are described here.
Blood stem cell mobilization and collection in patients with lymphoproliferative diseases: practical issues
Authors: Jantunen Esa , Kuittinen Taru
Published: March 2008

More than 15 000 autologous stem cell transplants (ASCT) were reported to European Blood and Bone Marrow Transplantation registry in 2005, most commonly for multiple myeloma (MM) and lymphomas. In 98% of the cases high‐dose therapy was supported by blood stem cells. Thus stem cell mobilization and collection are integral parts of ASCT protocols. We give here a practical approach to blood stem cell mobilization and collection in patients with various lymphoproliferative diseases. While mobilization is usually easy and straightforward in patients with MM, about 10–20% of patients with non‐Hodgkin’s lymphoma or Hodgkin’s lymphoma are hard‐to‐mobilize. There seems to be even more disease‐specific issues in blood stem cell mobilization in patients with chronic lymphocytic leukaemia and in patients with light chain amyloidosis. We also discuss options in hard‐to‐mobilize patients.
A Role for EHD4 in the Regulation of Early Endosomal Transport
Authors: Sharma Mahak , Naslavsky Naava , Caplan Steve
Published: March 2008

All four of the C‐terminal Eps15 homology domain (EHD) proteins have been implicated in the regulation of endocytic trafficking. However, the high level of amino acid sequence identity among these proteins has made it challenging to elucidate the precise function of individual EHD proteins. We demonstrate here with specific peptide antibodies that endogenous EHD4 localizes to Rab5‐, early embryonic antigen 1 (EEA1)‐ and Arf6‐containing endosomes and colocalizes with internalized transferrin in the cell periphery. Knock‐down of EHD4 expression by both small interfering RNA and short hairpin RNA leads to the generation of enlarged early endosomal structures that contain Rab5 and EEA1 as well as internalized transferrin or major histocompatibility complex class I molecules. In addition, cargo destined for degradation, such as internalized low‐density lipoprotein, also accumulates in the enlarged early endosomes in EHD4‐depleted cells. Moreover, we have demonstrated that these enlarged early endosomes are enriched in levels of the activated GTP‐bound Rab5. Finally, we show that endogenous EHD4 and EHD1 interact in cells, suggesting coordinated involvement in the regulation of receptor transport along the early endosome to endocytic recycling compartment axis. The results presented herein provide evidence that EHD4 is involved in the control of trafficking at the early endosome and regulates exit of cargo toward both the recycling compartment and the late endocytic pathway.