bluuebunny/crossref_metadata_2025_split huggingface dataset:
Essential role of clusterin in pancreas regeneration
Authors: Lee Song , Hong Seok‐Woo , Min Bon‐Hong , Shim Young‐Jun , Lee Ki‐Up , Lee In‐Kyu , Bendayan M. , Aronow Bruce J. , Park In‐Sun 
Published: February 2011

AbstractBased on our previous observations that clusterin induction accompanies pancreas regeneration in the rat, we sought to determine if regeneration might be impaired in mice that lacked clusterin. We studied the impact of absent clusterin on morphogenic and functional features of regenerating pancreas. Clusterin induction was accompanied in the regenerating pancreas by a robust development of new lobules with ductules, acini, and endocrine islets in wild type after partial pancreatectomy. In clusterin knock‐out mice, however, pancreatectomy resulted in a poor formation of regenerating lobule. In particular, regeneration of beta‐cells was also significantly reduced and was associated with persistent hyperglycemia. Duct cells obtained from pancreatectomized clusterin knock‐out mice exhibited impaired beta‐cell formation in vitro; this was restored by administration of exogenous clusterin. We suggest that clusterin plays a critical role to promote both exocrine and endocrine regeneration following pancreas injury, as well as for in vitro beta‐cell regeneration. Developmental Dynamics 240:605–615, 2011. © 2011 Wiley‐Liss, Inc.
Further Characterization of the [FeFe]‐Hydrogenase Maturase HydG
Authors: Tron Cécile , Cherrier Mickaël V. , Amara Patricia , Martin Lydie , Fauth Francois , Fraga Edmundo , Correard Mélanie , Fontecave Marc , Nicolet Yvain , Fontecilla‐Camps Juan C. 
Published: February 2011

AbstractRecent work conducted in several laboratories has shown that the [FeFe]‐hydrogenase maturase HydG synthesizes both CO and CN– from tyrosine. We have very recently found that although CN– synthesis does not need the [4Fe‐4S] cluster found in the HydG C‐terminal domain, CO synthesis does require it. We have also proposed that the +H2N·–CH2–CO2– radical is a precursor for these two active site ligands. Here, we have extended our characterization of both the wild‐type enzyme and a ThiH‐like HydG truncated mutant, with small angle X‐ray scattering (SAXS) spectroscopy, homology modeling and functional studies.
(5S)‐5‐(Trifluoromethyl)pyrrolidin‐2‐one as a Promising Building Block for Fluoroorganic Chemistry
Authors: Bezdudny Andrii V. , Alekseenko Anatoliy N. , Mykhailiuk Pavel K. , Manoilenko Olga V. , Shishkin Oleg V. , Pustovit Yurii M. 
Published: February 2011

AbstractPyroglutamic acid smoothly reacts with sulfur tetrafluoride at room temperature to afford enantiomerically pure (5S)‐5‐(trifluoromethyl)pyrrolidin‐2‐one (92 % yield, >99 % ee). Representative one‐step transformations of 1 provided both γ‐(S)‐trifluoromethyl GABA and (2S)‐2‐(trifluoromethyl)pyrrolidine on a multigram scale.
Highly Enantioselective Henry Reaction Catalyzed by C2‐Symmetric Modular BINOL‐Oxazoline Schiff Base Copper(II) Complexes Generated in Situ
Authors: Yang Wen , Du Da‐Ming 
Published: February 2011

AbstractA 16‐member library of C2‐symmetric modular chiral BINOL‐oxazoline Schiff base copper(II) complex catalysts generated in situ was easily generated in a one‐pot, three‐component manner. This approach avoided the need for isolation and characterization of ligands and greatly improved the catalyst screening efficiency. This modular catalyst library was evaluated in the asymmetric Henry reaction, for which good yields (up to 98 %) and good to excellent enantioselectivities (up to 98 % ee) were obtained under mild conditions.
Recent developments in electrophoretic separations on microfluidic devices
Authors: Kenyon Stacy M. , Meighan Michelle M. , Hayes Mark A. 
Published: February 2011

AbstractResearch combining the areas of separation science and microfluidics has gained popularity, driven by the increasing need to create portable, fast, and low analyte‐consumption devices. Much of this research has focused on the developments in electrophoretic separations, which use the electrokinetic properties of analytes to overcome many of the problems encountered during system scale‐down. In addition, new physical phenomenon can be exploited on the microscale not available in standard techniques. In this study, the innovative developments, including electrophoretic concentration, sample preparation/conditioning, and separation on‐chip are reviewed, along with some introductory discussions, from January 2008 to July 2010.
Accuracy and sensitivity of the determination of rate constants of interconversion in achiral and chiral environments by dynamic enantioselective electrophoresis
Authors: Svobodová Jana , Dubský Pavel , Tesařová Eva , Gaš Bohuslav 
Published: February 2011

AbstractThe method for determination of rate constants of interconversion of enantiomers in chiral and achiral environments of a dynamic enantioseparation system was investigated in order to reveal its accuracy, sensitivity and robustness. Two significantly different enantioseparation systems were selected, one with a single (well‐defined) chiral selector (CS) and the second with a mixture of CSs, and the rate constants of interconversion for these two systems were compared statistically. While the rate constants of interconversion in the chiral environment were found to be significantly different, the rate constants in achiral environment were confirmed to be statistically the same. The accuracy of the method was independent of experimental conditions. Influence of a CS and temperature on the rate of interconversion were discussed within the scope of determined thermodynamic parameters and statistical evaluation. A certain temperature may exist at which two different types of CSs influence the rate of interconversion equally while the extent of their influence may largely differ at other temperatures.
Regulation of the retention factor for weak acids in micellar electrokinetic chromatography with cationic surfactant via variation of the chloride concentration
Authors: Orentaitė Irma , Maruška Audrius , Pyell Ute 
Published: February 2011

AbstractFor tetradecyltrimethylammonium bromide in boric acid/borate or acetic acid/acetate buffer and NaCl or CaCl2 as the added salt, it is investigated whether the retention behaviour of weak acids in MEKC with cationic surfactant can be modelled by assuming for the deprotonated species predominantly electrostatic interaction with the micelles acting as a pseudostationary ion‐exchanger. The retention of (partially) charged solutes by oppositely charged micelles is analyzed by applying the classical theory of IEC (plotting lg k against lg(c(Cl−))) assuming a fixed concentration of ion‐exchange sites. When plotting the absolute slopes of the regression lines against the absolute effective charge numbers of the analytes, correlation coefficients of 0.968–0.998 were obtained. It is shown that the dependence of the retention factor on the concentration of chloride (the competing ion) in the separation electrolyte and on the degree of dissociation of the analyte corresponds to what would be expected for mixed‐mode retention (hydrophobic and ion‐exchange interaction) on a pseudostationary ion‐exchanger.
Chip‐based detection system for the on‐site analysis of animal diseases
Authors: Seise Barbara , Brinker Anja , Kretschmer Robert , Schwarz Martha , Rudolph Bettina , Kaulfuß Toni , Urban Matthias , Henkel Thomas , Popp Jürgen , Möller Robert 
Published: February 2011

AbstractA portable and robust system which is suitable for the automated analysis of DNA or RNA of selected pathogens such as foot‐and‐mouth disease virus (FMDV) is developed. The system incorporates a stationary PCR chip and is coupled with a DNA chip and an electrical detection for the sequence‐specific identification of the PCR products. The PCR chip represents a miniaturized form of the classical thermocyclers and enables a fast and sensitive amplification as well as labeling of specific DNA sequences with minimal space and energy requirements. The detection and identification of the PCR products is performed on a DNA chip with an electrical detection scheme. The combination of the two technologies allows a very fast and highly specific sequence‐based detection and differentiation of pathogens. Further, it combines the accuracy of sequence analysis with the speed of chip technologies. For the total analysis including DNA amplification and DNA detection, less than 2 h are required.
Lipase‐catalyzed esterification of palmarosa oil
Authors: Daniel David K. , Malik Soni , Albert Krastanov 
Published: February 2011

AbstractThe present study was carried out with free lipase to study the conversion of geraniol of palmarosa oil to geranyl acetate using acetic acid as acyl donor. The significant factors such as temperature, enzyme concentration and molar ratio of the reactants were investigated for their effects on the ester conversion. A temperature of 60°C and 50 μL of the enzyme solution were found to give the best results for 75 mM of each substrate. The percentage of esterification estimated by both gas chromatographic analysis (which indicated product formation) and titrimetry (which showed acid consumption, i.e. ester formed) was found to be in good agreement. A mechanism for the reaction was proposed, involving nonlinear inhibition studies (inhibition by acid), validation of the reaction and prediction of the kinetic parameters using polymath. Substrate inhibition with dead end complex of acetic acid was found to represent the kinetic data.
Combination of biosorption and photodegradation to remove methyl orange from aqueous solutions
Authors: Yu Jun‐Xia , Chi Ru‐An , He Zheng‐Yan , Qi Ya‐Feng , Zhan Guang , Guo Jia 
Published: February 2011

AbstractIn this study, metal ion‐modified biomass of waste beer yeast was prepared to improve its adsorption capacity for an anionic dye: methyl orange. The adsorption capacities of Fe3+‐, Mg2+‐, Ca2+,‐ and Na+‐modified biomass preparations for methyl orange were 90.8, 51.3, 23.0, and 20.6 mg/g, which were 30, 17, 8, and 7 times that of the unmodified biomass, respectively. Adsorption isotherm experiments showed that the Freundlich model gave better fits than the Langmuir model for methyl orange adsorption on Fe3+‐, Mg2+‐, Ca2+‐modified and unmodified biomass, whereas on Na+‐modified biomass the Langmuir model gave better fits. The sorption and desorption kinetics of methyl orange on Fe3+‐ and Mg2+‐modified biomass both fitted well to the pseudo‐second‐order kinetic models, with R≥0.998, and the desorption processes in NaOH solution (pH 12) were very fast in attaining equilibrium, i.e. within 15 min. In order to avoid secondary pollution, the eluent containing the desorbed methyl orange was treated with a photocatalyst: P25. After that, the eluent could be reused, and thus saving a large volume of eluent.
Survival and precopulatory guarding behavior of Hyalella azteca (Amphipoda) exposed to nitrate in the presence of atrazine
Authors: Pandey Ram B , Adams Ginny L , Warren Laurie W 
Published: February 2011

Abstract
Nitrate is one of the most commonly detected contaminants found in aquatic systems with other pesticides such as atrazine. The current study examined potential combined effects of nitrate and atrazine on adults of the freshwater amphipod Hyalella azteca, using survival and precopulatory guarding behavior as toxic endpoints. Although significant differences in acute toxicity with nitrate alone and in binary combination with atrazine (200 µg/L) in water-only tests were not consistently observed for each time point, potential biologically relevant trends in the data were observed. Posttest growth and behavioral observations (10-day period) conducted after 96-hour exposure suggested that atrazine and nitrate at these concentrations did not result in delayed effects on H. azteca. However, when test conditions were modified from standard toxicity tests by feeding amphipods, nitrate was found to be more toxic, with a reduction in median lethal concentration (LC50) values of approximately 80%. We also demonstrated that nitrate exhibits a dose–response effect on precopulatory guarding behavior of H. azteca, suggesting that reproductive effects may occur at environmentally relevant concentrations. Environ. Toxicol. Chem. 2011; 30:1170–1177. © 2011 SETAC
Osteogenic differentiation of human adipose‐derived stem cells induced by osteoinductive calcium phosphate ceramics
Authors: Li Xiaoming , Liu Haifeng , Niu Xufeng , Fan Yubo , Feng Qingling , Cui Fu‐zhai , Watari Fumio 
Published: February 2011

AbstractMicrostructure is indispensable for the osteoinduction of calcium phosphate ceramics. To study how microstructure takes its role and explore the mechanism of the osteoinduction, we evaluated attachment, proliferation, alkaline phosphatase (ALP)/DNA, protein/DNA, and mineralization of human adipose‐derived stem cells cultured on two kinds of biphasic calcium phosphate (BCP) ceramic discs with the same chemistry and dimension, but different microporosity and surface area. BCP‐A had been found osteoinductive in vivo while BCP‐B was not. During the conventional culture, ALP/DNA and protein/DNA of the cell on BCP‐A with larger surface area were significantly higher than those of the cells on BCP‐B. With the adsorption of the proteins in culture medium with 50% fetal bovine serum (FBS) in advance, the increments of the ALP/DNA and protein/DNA for the BCP‐A were found respectively significantly more than the increments of those for BCP‐B, suggesting that the larger amount of protein adsorbed on the BCP‐A was crucial. More results showed that ALP/DNA and protein/DNA of the cells on the two kinds of discs presoaked in culture medium having additional rhBMP‐2 were found to be both higher than those of the cells on the discs resoaked in culture medium with 50% FBS, and that those values for BCP‐A increased much more. Furthermore, larger mineral content was found on BCP‐A than on BCP‐B at day 7. The results indicated that by increasing microporosity and thus surface areas, osteoinductive calcium phosphate ceramics concentrate more proteins, including bone‐inducing proteins, and thereafter stimulate inducible cells in soft tissues to form inductive bone. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Preparation and properties of nano‐hydroxyapatite/PCL‐PEG‐PCL composite membranes for tissue engineering applications
Authors: Fu Shao Zhi , Wang Xiu Hong , Guo Gang , Shi Shuai , Fan Min , Liang Hang , Luo Feng , Qian Zhi Yong 
Published: February 2011

AbstractNano‐hydroxyapatite (n‐HA)/poly(ε‐caprolactone)‐poly(ethylene glycol)‐poly(ε–caprolactone) (PCL‐PEG‐PCL, PCEC) composite membranes were prepared by solvent casting and evaporation method. The structure and properties of the membranes were investigated by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle measurements, in vitro hydrolytic degradation, mechanical test, and cell culture. The effect of n‐HA content on physical–chemical properties of the n‐HA/PCEC composite membranes was studied. The results showed that the shape and size of micropores of the composite membranes changed with n‐HA content increased; the tensile strength decreased with the increase of n‐HA content. The osteoblast cell was cultured on the membranes, good cell attachment and growth manner were observed after postseeding for 1 day. MTT assays showed that the n‐HA/PCEC membranes had no negative effect on the cell viability and proliferation. These results suggested that the obtained n‐HA/PCEC composite membranes in this study might have prospective applications in tissue engineering field. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Optically based‐indentation technique for acute rat brain tissue slices and thin biomaterials
Authors: Lee S. J. , Sun J. , Flint J. J. , Guo S. , Xie H. K. , King M. A. , Sarntinoranont M. 
Published: February 2011

AbstractCurrently, micro‐indentation testing of soft biological materials is limited in its capability to test over long time scales due to accumulated instrumental drift errors. As a result, there is a paucity of measures for mechanical properties such as the equilibrium modulus. In this study, indentation combined with optical coherence tomography (OCT) was used for mechanical testing of thin tissue slices. OCT was used to measure the surface deformation profiles after placing spherical beads onto submerged test samples. Agarose‐based hydrogels at low‐concentrations (w/v, 0.3–0.6%) and acute rat brain tissue slices were tested using this technique over a 30‐min time window. To establish that tissue slices maintained cell viability, allowable testing times were determined by measuring neuronal death or degeneration as a function of incubation time with Fluor‐Jade C (FJC) staining. Since large deformations at equilibrium were measured, displacements of surface beads were compared with finite element elastic contact simulations to predict the equilibrium modulus, μ∞. Values of μ∞ for the low‐concentration hydrogels ranged from 0.07 to 1.8 kPa, and μ∞ for acute rat brain tissue slices was 0.13 ± 0.04 kPa for the cortex and 0.09 ± 0.015 kPa for the hippocampus (for Poisson ratio = 0.35). This indentation technique offers a localized, real‐time, and high resolution method for long‐time scale mechanical testing of very soft materials. This test method may also be adapted for viscoelasticity, for testing of different tissues and biomaterials, and for analyzing changes in internal structures with loading. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Bacterial cellulose as a potential vascular graft: Mechanical characterization and constitutive model development
Authors: Zahedmanesh H. , Mackle J. N. , Sellborn A. , Drotz K. , Bodin A. , Gatenholm P. , Lally C. 
Published: February 2011

AbstractBacterial cellulose (BC) is a polysaccharide produced by Acetobacter Xylinum bacteria with interesting properties for arterial grafting and vascular tissue engineering including high‐burst pressure, high‐water content, high crystallinity, and an ultrafine highly pure fibrous structure similar to that of collagen. Given that compliance mismatch is one of the main factors contributing to the development of intimal hyperplasia in vascular replacement conduits, an in depth investigation of support mechanical properties of BC is required to further supporting its use in cardiovascular‐grafting applications. The aim of this study was to mechanically characterize BC and also study its potential to accommodate vascular cells. To achieve these aims, inflation tests and uniaxial tensile tests were carried out on BC samples. In addition, dynamic compliance tests were conducted on BC tubes, and the results were compared to that of arteries, saphenous vein, expanded polytetrafluoroethylene, and Dacron grafts. BC tubes exhibited a compliance response similar to human saphenous vein with a mean compliance value of 4.27 × 10−2 % per millimeter of mercury over the pressure range of 30–120 mmHg. In addition, bovine smooth muscle cells and endothelial cells were cultured on BC samples, and histology and fluorescent imaging analysis were carried out showing good adherence and biocompatibility. Finally, a method to predict the mechanical behavior of BC grafts in situ was established, whereby a constitutive model for BC was determined and used to model the BC tubes under inflation using finite element analysis. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Integration of cellulases into bacterial cellulose: Toward bioabsorbable cellulose composites
Authors: Hu Yang , Catchmark Jeffrey M. 
Published: February 2011

AbstractCellulose biodegradation resulting from enzymolysis generally occurs in nature rather than in the human body because of the absence of cellulose degrading enzymes. In order to achieve in‐vivo degradation in human body for in‐vivo tissue regeneration applications, we developed a bioaborbable bacterial cellulose (BBC) material, which integrates one or more cellulose degrading enzymes (cellulases), and demonstrated its degradability in vitro using buffers with pH values relevant to wound environments. We introduced a double lyophilizing process to retain the microstructure of the bacterial cellulose as well as the activity of embedded enzymes allowing for long‐term storage of the material, which only requires hydration before use. Enzymes and their combinations have been examined to optimize the in‐vitro degradation of the BBC material. In‐vitro studies revealed that acidic cellulases from Trichoderma viride showed reasonable activity for pH values ranging from 4.5 to 6.0. A commercial cellulase (cellulase‐5000) did not show good activity at pH 7.4, but its degrading ability increased when used in conjunction with a β‐glucosidase from Bacillus subtilis or a β‐glucosidase from Trichoderma sp. Given the harmless glucose product of the enzymatic degradation of cellulose, the BBC material may be ideal for many wound care and tissue engineering applications for the bioabsorbable purpose. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
In vivo biological performance of a novel highly bioactive glass‐ceramic (Biosilicate®): A biomechanical and histomorphometric study in rat tibial defects
Authors: Granito Renata N. , Rennó Ana Claudia , Ravagnani Christian , Bossini Paulo S. , Mochiuti Daniel , Jorgetti Vanda , Driusso Patricia , Peitl Oscar , Zanotto Edgar D. , Parizotto Nivaldo A. , Oishi Jorge 
Published: February 2011

AbstractThis study aimed to investigate bone responses to a novel bioactive fully crystallized glass‐ceramic of the quaternary system P2O5‐Na2O‐CaO‐SiO2 (Biosilicate®). Although a previous study demonstrated positive effects of Biosilicate® on in vitro bone‐like matrix formation, its in vivo effect was not studied yet. Male Wistar rats (n = 40) with tibial defects were used. Four experimental groups were designed to compare this novel biomaterial with a gold standard bioactive material (Bioglass® 45S5), unfilled defects and intact controls. A three‐point bending test was performed 20 days after the surgical procedure, as well as the histomorphometric analysis in two regions of interest: cortical bone and medullary canal where the particulate biomaterial was implanted. The biomechanical test revealed a significant increase in the maximum load at failure and stiffness in the Biosilicate® group (vs. control defects), whose values were similar to uninjured bones. There were no differences in the cortical bone parameters in groups with bone defects, but a great deal of woven bone was present surrounding Biosilicate® and Bioglass® 45S5 particulate. Although both bioactive materials supported significant higher bone formation; Biosilicate® was superior to Bioglass® 45S5 in some histomorphometric parameters (bone volume and number of osteoblasts). Regarding bone resorption, Biosilicate® group showed significant higher number of osteoclasts per unit of tissue area than defect and intact controls, despite of the non‐significant difference in the osteoclastic surface as percentage of bone surface. This study reveals that the fully crystallized Biosilicate® has good bone‐forming and bone‐bonding properties. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.