bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flavonoids‐induced accumulation of hypoxia‐inducible factor (HIF)‐1α/2α is mediated through chelation of iron
Authors: Park Sung‐Soo , Bae Insoo , Lee Yong J. 
Published: October 2007

AbstractHypoxia‐inducible factor‐1 alpha (HIF‐1α) is the regulatory subunit of the heterodimeric transcription factor HIF‐1 that is the key regulator of cellular response to low oxygen tension. Under normoxic conditions, HIF‐1α is continuously degraded by the ubiquitin‐proteasome pathway through pVHL (von Hippel–Lindau tumor suppressor protein). Under hypoxic conditions, HIF‐1α is stabilized and induces the transcription of HIF‐1 target genes. Quercetin, a flavonoid with anti‐oxidant, anti‐inflammatory, and kinase modulating properties, has been found to induce HIF‐1α accumulation and VEGF secretion in normoxia. In this study, the molecular mechanisms of quercetin‐mediated HIF‐1α accumulation were investigated. Previous studies have shown that, in addition to being induced by hypoxia, HIF‐1α can be induced through the phosphatidylinositol 3‐kinase (PI3K)/Akt and p53 signaling pathways. But our study revealed, through p53 mutant‐type as well as p53 null cell lines, that neither the PI3K/Akt nor the p53 signaling pathway is required for quercetin‐induced HIF‐1α accumulation. And we observed that HIF‐1α accumulated by quercetin is not ubiquitinated and the interaction of HIF‐1α with pVHL is reduced, compared with HIF‐1α accumulated by the proteasome inhibitor MG132. The use of quercetin's analogues showed that only quercetin and galangin induce HIF‐1/2α accumulation and this effect is completely reversed by additional iron ions. This is because quercetin and galangin are able to chelate cellular iron ions that are cofactors of HIF‐1/2α proline hydroxylase (PHD). These data suggest that quercetin inhibits the ubiquitination of HIF‐1/2α in normoxia by hindering PHD through chelating iron ions. J. Cell. Biochem. 103: 1989–1998, 2007. © 2007 Wiley‐Liss, Inc.
Mutational robustness and geometrical form in protein structures
Authors: Hartling Julia , Kim Junhyong 
Published: October 2007

AbstractTheoretical studies of RNA and lattice protein models suggest that mutationally robust or the so‐called designable phenotypes tend to have special geometric features such as being more compact and more geometrically regular. Such geometrical forms have been also linked to speed of folding and stability properties that may also assist in promoting mutational robustness. Here we test these theoretical predictions on a non‐redundant collection of 2,660 experimentally determined structures from the PDB (Protein Data Bank) and CATH (Class Architecture Topology Homologous superfamily) database. We first developed an index summarizing the geometrical regularity of the structures and then used this index to show that the statistical pattern of empirical data is consistent with the theoretical predictions relating geometry to mutational robustness. Mutationally robust proteins tend to be more symmetric and compact. But, the relationship between compactness and robustness cannot be explained simply by the geometrical packing of individual amino acids in proteins; rather, it is the property of the whole system that is related to the statistical characteristics of the folding landscape. Finally, we hypothesize that a triplet relationship between mutational robustness, stability and form is a general properties of objects that optimize real‐valued relationships between sequences and discrete structures. J. Exp. Zool. (Mol. Dev. Evol.) 310B:216–226, 2008. © 2007 Wiley‐Liss, Inc.
Changes of the bone mineral density in proximal femur following total hip resurfacing arthroplasty in osteonecrosis of femoral head
Authors: Lian Yong‐yun , Pei Fu‐xing , Yoo Myung‐chul , Cheng Jing‐qiu , Fatou Camara‐yagouba 
Published: October 2007

AbstractTotal hip resurfacing arthroplasty (THRA) is being performed with increasing frequency for osteonecrosis of femoral head (ONFH). To evaluate femoral bone remodeling in ONFH after THRA and determine the impact of stem‐neck angle (SNA) of inserted femoral component on bone remodeling, we monitored the changes in BMD in proximal femur in 23 patients with ONFH after surgery. Patients were divided into group A (SNA ≥ 5°) and group B (SNA < 5°). The BMD was measured in seven Gruen zones and two neck zones using dual‐energy X‐ray absorptiometry preoperatively, then at 3, 6, 12, and 24 months after surgery. At all ROIs, the BMD decreased significantly by 3 months postoperatively. The BMD ceased to decrease and reversed by 6 months. The BMD in neck increased significantly in group A, compared with group B at 24 months. The BMD increased 2% at ROI1 at 24 months in both groups, and at ROI7, the BMD in group A reversed to baseline value by 6 months and increased 5.81% at 24 months. These findings implied that the bone stock of proximal femur in ONFH can be well reserved after total hip resurfacing arthroplasty with valgus positioning of the femoral component. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:453–459, 2008
Quantitative characterization of gait kinematics in patients with hallux rigidus using the Milwaukee foot model
Authors: Canseco Karl , Long Jason , Marks Richard , Khazzam Michael , Harris Gerald 
Published: October 2007

AbstractThe purpose of this study was to provide a quantitative analysis of the changes that occur in the foot and ankle during the gait of patients with hallux rigidus. Using a 15‐camera Vicon Motion Analysis System, gait analysis was conducted on a population of 22 patients with hallux rigidus and compared to that of 25 healthy ambulators. Weight‐bearing radiographs were measured to index marker positions to underlying bony anatomy. The Milwaukee Foot Model was used to perform three‐dimensional analysis of dynamic foot and ankle motion, and temporal–spatial parameters were also calculated. Values were compared to controls using unpaired parametric methods (Student t‐test, p < 0.002). The hallux rigidus population showed significant alterations in gait patterns as compared to controls in various planes in all segments (hallux, forefoot, hindfoot, and tibia) of the foot and ankle, particularly in the range of motion of the hallux and the forefoot. Prolonged stance phase was also observed. As reports regarding the quantitative study of the multisegment foot and ankle are limited, this study was useful in providing characterization of gait patterns in patients with hallux rigidus. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:419–427, 2008
Navigated lower limb axis measurements: Influence of mechanical weight‐bearing simulation
Authors: Kendoff Daniel , Board Timothy N. , Citak Musa , Gardner Michael J. , Hankemeier Stefan , Ostermeier Sven , Krettek Christian , Hüfner Tobias 
Published: October 2007

AbstractSuccessful outcomes following high tibial osteotomy (HTO) require precise realignment of the mechanical axis of the lower extremity. The inability to accurately assess the weight‐bearing axis intraoperatively may account for inappropriate degrees of correction with the osteotomy. We tested the hypothesis that axial loading of the limb affects alignment during an HTO procedure. A custom mechanical load apparatus was developed to simulate weight‐bearing conditions intraoperatively. Fixation to the trunk was achieved by supraacetabular pins and an external fixation device, which allowed the pelvis to be rigidly fixed relative to the apparatus while axial load was applied to the foot. Ten fresh cadavers were used for testing. The baseline mechanical axis was determined by a navigation system. HTO was then performed, and varying degrees of valgus correction were obtained and stabilized. For each correction, one quarter, one half, or full body weight was applied axially to the foot, and the axis deviation was measured. Subsequently, the MCL was sequentially released to determine the effect of ligament incompetence. Prior to osteotomy, load application did not produce significant axis deviations. Following osteotomy, the mechanical axis deviation shifted significantly in all trials, increasing as load magnitude and degree of correction increased. With complete sectioning of the MCL, a further significant shift in the axis occurred. Deviations of mechanical axis occur on weight bearing in lower limbs following HTO. These shifts must be considered and possibly quantified to achieve the desired axis correction and maximize the chance at a successful long term outcome. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:553–561, 2008
In vivo release of the antimicrobial peptide hLF1‐11 from calcium phosphate cement
Authors: Stallmann Hein P. , Roo Ronald de , Faber Chris , Amerongen Arie V. Nieuw , Wuisman Paul I.J.M. 
Published: October 2007

AbstractWe studied the release of human lactoferrin 1‐11 (hLF1‐11), a potent antimicrobial peptide, in an animal model. Calcium phosphate cement with 50 mg/g hLF1‐11 was injected into the femoral canal of 12 rabbits. One, 3, and 7 days later, four animals were terminated, and the femora excised. Sections of bone and cement were removed for histological analysis. We used liquid chromatography‐mass spectrometry/mass spectrometry for semiquantitative determination of the hLF1‐11 concentration. Blood samples were drawn for leukocyte count and differentiation to identify a potential immunomodulating effect of hLF1‐11. After an initial burst release, the hLF1‐11 concentration in cement and bone decreased steadily. This in vivo release profile is consistent with earlier in vitro studies. Tissue ingrowth into the cement, without signs of inflammation or necrosis, was observed. Leukocytosis or a shift in leukocyte differentiation did not occur. The carrier released over 99% of the hLF1‐11, resulting in peak concentrations at the cement–bone interface. This indicates that hLF1‐11 could become a valuable prophylactic agent in osteomyelitis treatment. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:531–538, 2008
Induction of chondrogenesis and superficial zone protein accumulation in synovial side population cells by BMP‐7 and TGF‐β1
Authors: Yamane Shintaro , Reddi A. Hari 
Published: October 2007

AbstractSynovial cells are known to contain a sub‐population of cells with multipotent differentiating capacity including chondrocytes. However, the stem/progenitor cells in synovial cells have not been well characterized. Stem/progenitor cells can exclude Hoechst 33342 dye, and the cell fraction with this property is called “side population (SP).” SP cells are present in many adult tissues. The aim of this investigation was to identify, isolate, and characterize SP cells from bovine synovium. Hoechst dye efflux and fluorescence activated cell sorting showed that synovial cells contained 0.60% SP cells. In the presence of verapamil, an inhibitor of ABC transporters critical for the dye efflux property, the SP cell fraction was not observed, indicating the critical role of ABC transporters. Isoforms of ABC transporters (ABCG2 and ABCB1 mRNA) were highly expressed in SP cells derived from the synovial cells by real‐time RT‐PCR analysis. Bone morphogenetic protein‐7 (BMP‐7) induced type II collagen mRNA expression characteristic of chondrogenesis in articular cartilage with both SP and non‐SP cells. In addition, expression of SZP mRNA, a marker of the surface layer of articular cartilage, was significantly up‐regulated by BMP‐7, and the protein accumulation of SZP was stimulated by both BMP‐7 and TGF‐β1. Thus, synovial cells contain ABC transporter‐dependent SP cells. These findings demonstrate that side population cells of synovium differentiate toward an articular chondrocyte phenotype of the surface layer and have direct implications for tissue engineering and regeneration of articular cartilage. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:485–492, 2008
A rapid and sensitive UPLC‐ESI MS method for analysis of isofraxidin, a natural antistress compound, and its metabolites in rat plasma
Authors: Sun Hui , Lv Haitao , Zhang Yanmei , Wang Xijun , Bi Kaishun , Cao Hongxin 
Published: October 2007

AbstractIsofraxidin is one of the main bioactive constituents in the root of Acanthopanax senticosus, which has antifatigue, antistress, and immuno‐accommondating effects. In this study, an ultraperformance LC (UPLC)‐ESI MS method was developed for analyzing isofraxidin and its metabolites in rat plasma. The analysis was performed on a UPLC coupled with ESI MS (quadropole MS tandem TOF MS). The lower LOD (LLOD) for isofraxidin was 0.25 ng/mL, the intraday precision was less than 10%, the interday precision was less than 10%, and the extraction recovery was more than 80%. Isofraxidin and two metabolites (M1 and M2) were detected in rat plasma after oral administration of isofraxidin, and the molecular polarities of M1 and M2 were both increased compared to isofraxidin. The metabolites were identified as 5,6‐dihydroxyl‐7‐methoxycoumarin and 5‐hydroxyl‐6,7‐dimethoxycoumarin when subjected to parent ion spectra, product ion spectra, and extract mass and element composition analyses.
Development of an HPLC method for the determination of salidroside in beagle dog plasma after administration of salidroside injection: Application to a pharmacokinetics study
Authors: Mao Yu , Zhang Xinrong , Zhang Xiaodong , Lu Guocai 
Published: October 2007

AbstractA simple RP‐HPLC method was established for the determination of salidroside in dog plasma. Salidroside is one of the most active ingredients of Rhodiola L. The method had within‐run precision values in the range of ± 2.3 to ± 9.1% (n = 5) and between‐run precision in the range of ± 3.2 to ± 9.8%. A simple protein precipitation for salidroside extraction was processed using ACN at precipitant‐to‐plasma volume ratio (P–P ratio) of 3:2. The extraction recoveries of salidroside at seven concentrations were higher than 63.2%. There was a linear relationship between chromatographic area and concentration over the range of 0.83–520 μg/mL for salidroside in plasma (R = 0.9926). The LOQ (S/N = 10) of the method was 0.83 μg/mL. The method was applied in a study of the pharmacokinetics of salidroside injection in six beagle dogs. The major pharmacokinetic parameters of Cmax, AUC0–24, AUC0–∞, and t1/2 of salidroside in beagle dogs after i.v. administration of a single 75 mg/kg (5 mL/kg) dose were 96.16 ± 8.59 μg/mL, 180.3 ± 30.6 μg·h/mL, 189.3 ± 32.1 μg·h/mL, and 2.006 ± 0.615 h, respectively.
Separation of nucleic acid precursors on an amphoteric surfactant modified monolith using combined eluent flow, pH and concentration gradient
Authors: Nesterenko Ekaterina P. , Guivarc'h Céline , Duffy Cepta , Paull Brett 
Published: October 2007

AbstractAn RP monolithic column coated with an amphoteric carboxybetaine type surfactant has been used with a combined triple eluent concentration, pH and flow gradient ion chromatography technique for the simultaneous separation of up to 18 nucleotides, nucleosides and nucleobases. The separation of up to eight precursors on a 1 cm long monolithic microcolumn using the combined gradient approach is also shown. The method was applied to the separation of the above nucleic acid precursors in perchloric acid extracts of yeastolates samples.
Separation behavior of electron‐beam curing derived, acrylate‐based monoliths
Authors: Bandari Rajendar , Elsner Christian , Knolle Wolfgang , Kühnel Christa , Decker Ulrich , Buchmeiser Michael R. 
Published: October 2007

AbstractElectron beam (EB) curing‐derived monolith materials were prepared from ethyl methacrylate (EMA), trimethylolpropane triacrylate (TMPTA), 2‐propanol, 1‐dodecanol, and toluene within the confines of 3 mm×100 mm id glass columns, applying a total dose of 22 kGy for curing. Monolithic columns were checked for their separation behavior for selected dansylated (DNS)‐amino acids as well as for cyclophilin 18. Their separation performance was compared to that of a C18‐modified silica‐based rigid rod (Chromoliths®). In the separation of dansylated amino acids, retention times were reduced on EB‐derived columns, where the peak resolution was significantly better than on a Chromolith®. This finding was attributed to a larger fraction of small pores (< 2.15 nm) in the EB curing‐derived monoliths. Finally, EB curing‐derived monoliths have been used to separate cyclophilin 18 from crude cell lysis mixtures.
Evaluation of photografted charged sites within polymer monoliths in capillary columns using contactless conductivity detection
Authors: Connolly Damian , O'Shea Vincent , Clark Paul , O'Connor Brendan , Paull Brett 
Published: October 2007

AbstractCapacitively coupled contactless conductivity detection (C4D) is presented as a novel and versatile means of visualising discrete zones of charged functional groups grafted onto polymer based monoliths. Monoliths were first formed within 100 μm UV‐transparent fused silica capillaries. Photografting methods were subsequently used to graft a charged functional monomer, 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid, onto discrete regions of the monolith using a photomask. Post‐modification monolith evaluation involves scanning the C4D detector along the length of the monolith to obtain a profile of the exact spatial location of grafted charged functionalities with millimetre accuracy. The methodology was extended to the visualisation of several zones of immobilised protein (bovine serum albumin) using photografted azlactone groups to enable covalent attachment of the protein to the monolith at precise locations along its length. In addition, the extent of non‐specific binding of protein to the ungrafted regions of the monolith due to hydrophobic interactions could be monitored as an increase in background conductivity of the stationary phase. Finally, the technique was cross‐validated using digital photography in combination with a UV light source by immobilising green fluorescent protein in discrete zones and comparing the results obtained using both complementary techniques.
Thermal decomposition reaction and a comprehensive kinetic model of dimethyl ether
Authors: Zhao Zhenwei , Chaos Marcos , Kazakov Andrei , Dryer Frederick L. 
Published: October 2007

AbstractThe unimolecular decomposition reaction of dimethyl ether (DME) was studied theoretically using RRKM/master equation calculations. The calculated decomposition rate is significantly different from that utilized in prior work (Fischer et al., Int J Chem Kinet 2000, 32, 713–740; Curran et al., Int J Chem Kinet 2000, 32, 741–759). DME pyrolysis experiments were performed at 980 K in a variable‐pressure flow reactor at a pressure of 10 atm, a considerably higher pressure than previous validation data. Both unimolecular decomposition and radical abstraction are significant in describing DME pyrolysis, and hierarchical methodology was applied to produce a comprehensive high‐temperature model for pyrolysis and oxidation that includes the new decomposition parameters and more recent small molecule/radical kinetic and thermochemical data. The high‐temperature model shows improved agreement against the new pyrolysis data and the wide range of high‐temperature oxidation data modeled in prior work, as well as new low‐pressure burner‐stabilized species profiles (Cool et al., Proc Combust Inst 2007, 31, 285–294) and laminar flame data for DME/methane mixtures (Chen et al., Proc Combust Inst 2007, 31, 1215–1222). The high‐temperature model was combined with low‐temperature oxidation chemistry (adopted from Fischer et al., Int J Chem Kinet 2000, 32, 713–740), with some modifications to several important reactions. The revised construct shows good agreement against high‐ as well as low‐temperature flow reactor and jet‐stirred reactor data, shock tube ignition delays, and laminar flame species as well as flame speed measurements. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 1–18, 2008
Kinetics of the sulfate radical‐mediated photo‐oxidation of humic substances
Authors: Gara Pedro M. David , Bosio Gabriela N. , Gonzalez Mónica C. , Mártire Daniel O. 
Published: October 2007

AbstractThe kinetics of the aqueous phase reaction of sulfate radicals with commercial humic acids and with organic matter extracted from vermicompost (VC) was studied by flash‐photolysis. The results can be interpreted by a mechanism that in a first step considers the reversible binding of the sulfate radicals by the humic substances. Both the bound and free sulfate radicals decay to oxidized products. From experiments performed with Aldrich humic acids in the temperature range from 283 to 303 K, the enthalpy change associated with the binding process was estimated to be −(36 ± 11) kJ mol−1. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 19–24, 2008
Autocatalytic oxidation of β‐alanine by peroxomonosulfate in the presence of copper(II) ion
Authors: Kannan R. Sayee , Easwaramoorthy D. , Vijaya K. , Ramachandran M. S. 
Published: October 2007

AbstractKinetics and mechanism of oxidation of β‐alanine by peroxomonosulfate (PMS) in the presence of Cu(II) ion at pH 4.2 (acetic acid/sodium acetate) has been studied. Autocatalysis was observed only in the presence of copper(II) ion, and this was explained due to the formation of hydroperoxide intermediate. The rate constant for the catalyzed (k) and uncatalyzed (k) reaction has been calculated. The kinetic data obtained reveal that both the reactions are first order with respect to [PMS]. k values initially increase with the increase in [β‐alanine] and reach a limiting value, but k values decrease with the increase in [β‐alanine]. k values increase linearly with the increase in [Cu(II)], whereas k values increase with [Cu(II)]2. Furthermore, k values are independent of [acetate], but k values decrease with the increase in acetate. A suitable mechanism has been proposed to explain the experimental observation. The reaction has been studied at different temperatures, and the activation parameters are calculated. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 44–49, 2008
Experimental and modeling study of the autoignition of cyclopentene
Authors: Yahyaoui M. , Hakka M. H. , Glaude P. A. , Battin‐Leclerc F. 
Published: October 2007

AbstractIgnition delay times of cyclopentene–oxygen–argon mixtures were measured behind reflected shock waves. Mixtures contained 0.5% or 1% of hydrocarbons for equivalence ratios ranging from 0.5 to 1.5. Reflected shock wave conditions were as follows: temperatures from 1300 to 1700 K and pressures from 7 to 9 atm. When compared with the previous results obtained under similar conditions, it can be observed that the reactivity of cyclopentene is much lower than that of cyclohexene, but very close to that of cyclopentane. A kinetic mechanism recently proposed for the combustion of cyclopentene in a flame has been used to model these results, and a satisfactory agreement is obtained. The main reaction pathways have been derived from the flow rate, simulated temporal profiles of products, and sensitivity analyses. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 25–33, 2008