bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Polycomb and Trithorax activities during development
Authors: Soshnikova Natalia
Published: February 2011

Dynamic changes in gene expression are tightly controlled during development, as a single totipotent zygote gives rise to distinct cell lineages. The establishment and maintenance of these diverse transcriptional programs rely on changes of chromatin state, mainly through histone modifications. Polycomb and Trithorax complexes participate in setting apart active and inactive genes by respectively repressing and activating key developmental regulators in different cell types. Over the last decade, our understanding of the biochemical mechanisms underlying their activities has greatly improved, but the signals targeting these proteins to specific regions of the genome are still poorly understood, particularly in vertebrates. Recent findings highlight the highly dynamic activities of Polycomb and Trithorax complexes in vivo. Surprisingly, although their role in transcriptional regulation is deeply conserved during evolution, the time sequence in which they act seems to vary across species. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.
Signalling pathways and the host‐parasite relationship: Putative targets for control interventions against schistosomiasis
Authors: You Hong , Gobert Geoffrey N. , Jones Malcolm K. , Zhang Wenbao , McManus Donald P.
Published: February 2011

A better understanding of how schistosomes exploit host nutrients, neuro‐endocrine hormones and signalling pathways for growth, development and maturation may provide new insights for improved interventions in the control of schistosomiasis. This paper describes recent advances in the identification and characterisation of schistosome tyrosine kinase and signalling pathways. It discusses the potential intervention value of insulin signalling, which may play an important role in glucose uptake and carbohydrate metabolism in schistosomes, providing the nutrients essential for parasite growth, development and, notably, female fecundity. Significant progress has also been made in the characterisation of other schistosome growth factor receptors, such as transforming growth factor beta receptor and epidermal growth factor receptor, and in our understanding of their roles in the host‐parasite molecular dialogue and parasite development. The use of parasite signal transduction components as novel vaccine or drug targets may prove invaluable in prevention, treatment and control strategies to combat schistosomiasis.
How will fish that evolved at constant sub‐zero temperatures cope with global warming? Notothenioids as a case study
Authors: Patarnello Tomaso , Verde Cinzia , di Prisco Guido , Bargelloni Luca , Zane Lorenzo
Published: February 2011

Current climate change has raised concerns over the fate of the stenothermal Antarctic marine fauna (animals that evolved to live in narrow ranges of cold temperatures). The present paper focuses on Notothenioidei, a taxonomic group that dominates Antarctic fish. Notothenioids evolved in the Southern Ocean over the last 20 million years, providing an example of a marine species flock with unique adaptations to the cold at morphological, physiological and biochemical levels. Their phenotypic modifications are often accompanied by ‘irreversible’ genomic losses or gene amplifications. On a micro‐evolutionary scale, relatively ‘shallow’ genetic variation is observed, on account of past fluctuations in population size, and a significant genetic structure is evident, suggesting low population connectivity. These features suggest that Antarctic fish might have relatively little potential to adapt to global warming, at least at a genetic level. The extent of their phenotypic plasticity, which is evident to some degree, awaits further research.
Effectiveness of an instructional DVD in training college students to implement functional analyses
Authors: Trahan Maranda A. , Worsdell April S.
Published: February 2011

A functional analysis is a valuable assessment technique that requires a unique kind of precision on behalf of the therapist. However, there is a lack of empirically validated tools for training functional analysis skills. This study examined the effectiveness of an instructional DVD in training college students to perform five functional analysis conditions. During simulated sessions, participants acted as therapists, and observers measured the accuracy with which they implemented programmed antecedents and consequences. Results showed that the DVD was effective in improving all participants' accuracy above baseline levels; however, in order to meet the 90% performance criterion, all participants required feedback. These results suggest that an instructional video is a useful training tool in providing basic skills for conducting functional analyses. Copyright © 2011 John Wiley & Sons, Ltd.
Flow cytometric analysis of glyoxalase‐1 expression in human leukocytes
Authors: Skapare Elina , Riekstina Una , Liepinsh Edgars , Konrade Ilze , Makrecka Marina , Maurina Baiba , Dambrova Maija
Published: February 2011

Altered glyoxalase‐1 (GLO‐1) activity and expression is associated with the development of late diabetic complications, malignancy and oxidative stress‐ and aging‐related diseases. In the present study, we developed a flow cytometry method for GLO‐1 detection in human leukocytes isolated from peripheral blood samples to investigate GLO‐1 expression in leukocyte subsets from type 1 and 2 diabetes mellitus patients (n = 11) and healthy subjects (n = 8). The flow cytometry analysis of GLO‐1 in leukocytes showed that expression index of GLO‐1‐positive cells was slightly increased in mononuclear leukocytes from diabetic patients. This result correlated with the increase in GLO‐1 activity in the whole blood samples of type 2 diabetes patients. In conclusion, the present study demonstrates that flow cytometry is suitable for the detection of the GLO‐1 enzyme in human leukocytes and that this method could be used to investigate the fast adaptation of the glyoxalase system related to the pathogenesis of late complications of diabetes mellitus and other glycation stress‐related disorders. Copyright © 2011 John Wiley & Sons, Ltd.
Estrogen receptor alpha is essential for the proliferation of prostatic smooth muscle cells stimulated by 17β‐estradiol and insulin‐like growth factor 1
Authors: Zhou Dawei , Li Shiwen , Wang Xinghuan , Cheng Bei , Ding Xiegang
Published: February 2011

Estradiol (E2) and its receptor estrogen receptor alpha (ERα) are implicated in the pathology of stromal‐predominant benign prostatic hyperplasia (BPH). Insulin‐like growth factor 1(IGF1) is produced primarily by stromal cells in the prostate. Recent study showed that E2‐mediated regulation of IGF1 in mouse uterus requires the DNA binding ability of ERα. However, the crosstalk between ERα and IGF1 in the prostate has not been addressed yet. Therefore, in this study we employed mouse prostatic smooth muscle cells (PSMCs) as a model to demonstrate that E2 stimulated the proliferation of PSMCs and up‐regulated the expression of IGF1 and its receptor IGF1R as well as cyclin D1 in PSMCs, all of which could be inhibited by shRNA‐mediated knockdown of ERα. Furthermore, we found that exogenous IGF1 could not promote cell proliferation and cyclin D1 expression in PSMCs subjected to shRNA‐mediated knockdown of ERα. Interestingly, blockage of IGF1R by antibody could inhibit E2‐stimulated PSMCs proliferation. Altogether our present study provides the first line of evidence that there is crosstalk between ERα and IGF1 signaling in PSMCs proliferation in which ERα up‐regulates the expression of IGF1 and IGF1R, and IGF1 signaling is indispensable to mediate downstream effects of E2 and ERα. Copyright © 2011 John Wiley & Sons, Ltd.
Effects of structural analogues of nociceptin(1–13)NH2 on brain antioxidant status in kainic acid‐treated rats
Authors: Tzvetanova Elina , Nenkova Galina , Georgieva Almira , Alexandrova Albena , Girchev Radoslav , Kirkova Margarita
Published: February 2011

The in vivo effects of nociceptin (N/OFQ(1–13)NH2) and its structural analogues ([Dab9]N/OFQ(1–13)NH2, [Dap9]N/OFQ(1–13)NH2 and [Cav9]N/OFQ(1–13)NH2) on the levels of lipid peroxidation and cell antioxidants (enzyme and non‐enzyme) in brain of control and kainic acid (KA)‐treated rats were studied. In control animals, [Dab9]N/OFQ(1–13)NH2 and [Dap9]N/OFQ(1–13)NH2, unlike N/OFQ(1–13)NH2 and [Cav9]N/OFQ(1–13)NH2, slightly increased the brain lipid peroxidation; the rest of the parameters were unchanged by all neuropeptides tested. KA (0.25 µg in 0.5 µl, i.c.v) increased the lipid peroxidation (4 and 24 h after KA‐injection) and decreased the glutathione level (1 h after KA‐administration). One hour after KA‐administration, the neuropeptides (2 µg in 0.5 µl, injected 30 min before KA) showed the following effects: a slight decrease in the KA‐induced lipid peroxidation by all nociceptin analogues and an enhancement of the KA‐decreased GSH level, but by [Cav9]N/OFQ(1–13)NH2 only. The brain antioxidant enzyme activities were unchanged in all used experimental groups. In addition, the nociceptin analogues, especially [Can9]N/OFQ(1–13)NH2, showed a good antioxidant capacity in chemical systems, generating reactive oxygen species. In conclusion, the substitution of lysin (Lys) in N/OFQ(1–13)NH2 molecule with other amino acids might contribute to changes in its antioxidant properties. Copyright © 2011 John Wiley & Sons, Ltd.
Stacked PLS for calibration transfer without standards
Authors: Ni Wangdong , Brown Steven D. , Man Ruilin
Published: February 2011

We report the successful application of stacked partial least‐squares (SPLS) regression for direct application of multivariate calibration models to data from a secondary spectrometer, without use of any calibration transfer. Unlike a conventional calibration that requires transfer methods which need measurement of a set of transfer samples to make useful predictions from data obtained on a secondary instrument, SPLS regression can be used to generate regression models with good predictive power on both primary and secondary instruments. Results of direct application of SPLS to lake sediment data without use of any transfer standards show predictive results comparable to those obtained from conventional PLS calibration followed by a model updating (MUP) step. We also demonstrate the use of calibration MUP applied to stacked PLS regression, which further minimizes local differences between two instruments. Copyright © 2011 John Wiley & Sons, Ltd.
Novel and Efficient Copper‐Catalysed Synthesis of Nitrogen‐Linked Medium‐Ring Biaryls
Authors: Kenwright Jayne L. , Galloway Warren R. J. D. , Blackwell David T. , Isidro‐Llobet Albert , Hodgkinson James , Wortmann Lars , Bowden Steven D. , Welch Martin , Spring David R.
Published: February 2011

Herein, a new copper‐catalysed strategy for the synthesis of rare nitrogen‐linked seven‐, eight‐ and nine‐membered biaryl ring systems is described. It is proposed that the reaction proceeds through a highly activated intramolecularly co‐ordinated copper catalyst. The process is technically simple, proceeds under relatively mild conditions, displays a broad substrate scope and forms biologically valuable products that are difficult to synthesise by other methods. We envisage that this methodology will prove useful in a wide synthetic context, with possible applications in both target‐oriented and diversity‐oriented synthesis.
Lob des CO2. Das verrufene Gas
Authors: Soentgen Jens
Published: February 2011

Die in der öffentlichen Diskussion verbreitete Charakterisierung von CO2 als Klimakiller wird in diesem Essay als Projektion kritisiert: Mit der Vokabel “Klimakiller” wird aus einem politischen und kulturellen Problem ein technisches gemacht. Zugleich wird der Blick auf das CO2 selbst verstellt. Daher stellt sich der Autor in die Tradition der enkomia paradoxa, der paradoxen Lobreden und stimmt eine Laudatio auf das CO2 an. Er zieht dazu Fakten aus der Religionsgeschichte, aus der Wissenschaftsgeschichte, aus der Kulturgeschichte und insbesondere aus der ökologischen Chemie heran und stellt sie in einen größeren Zusammenhang. Ziel ist es, durch notwendige Provokationen zu einem realitätsnäheren Bild des Stoffes CO2 zu gelangen. Experimente mit CO2, darunter auch das einfachstmögliche Experiment zum Treibhauseffekt, ergänzen die Darstellung.
Raman‐Spektroskopie. Biomedizinische Diagnostik
Authors: Schmitt Michael , Popp Jürgen
Published: February 2011

Die Raman‐Mikrospektroskopie hat sich in den letzten Jahren aufgrund ihrer Labelfreiheit und ihrer hohen molekularen Selektivität als extrem leistungsstarke Analysenmethode für die biomedizinische Diagnostik etabliert. So gelingt es mittels der Raman‐Mikrospektroskopie Mikroorganismen wie bakterielle Krankheiterreger auf Einzelzellebene schnell zu identifizieren und charakterisieren. Lineare Raman‐Spektroskopie und nichtlineare Raman‐Techniken wie die CARS‐Mikroskopie besitzen großes Potenzial zur objektiven Beurteilung von Zellen oder Gewebe zur Frühdiagnose von Krankheiten wie Krebs.
Ein Elektronisches Laborjournal
Authors: Gooßen Lukas , Rudolphi Felix
Published: February 2011

Mancher Chemiker wird sich fragen, warum wir heutzutage Briefe mit dem Computer schreiben, unsere Zeitung im Internet lesen, aber unsere Experimente und Beobachtungen in vielen Fällen von Hand in Laborbüchern beschreiben. Warum verzichten wir an dieser Stelle auf die Vorzüge der Computertechnik?
Mangan
Authors: Schwedt Georg
Published: February 2011

Das seit fast 200 Jahren bestehende Mineralogische Museum der Universität Bonn, das 1874 eine bedeutende Sammlung vom Gründer des heutigen Rheinischen Mineralien‐Kontors A. Krantz erhielt, zeigt unter anderem systematisch geordnet Minerale zu ausgewählten chemischen Elementen. Sie werden in dieser Serie zum Internationalen Jahr der Chemie 2011 näher vorgestellt.
Das Diamant‐Gitter, Kristallstrukturen und Molekül‐Modelle
Authors: Quadbeck‐Seeger Hans‐Jürgen
Published: February 2011

Die Bemühungen, kostengünstige Molekül‐Modelle für Schule und Studium zu entwerfen, haben zu ungewöhnlichen Ergebnissen geführt. Das Ziel ist einfach und klar: Junge Menschen sollen sich eigene Modelle bauen können, die das räumliche Vorstellungsvermögen fördern und fordern. Die Wege von den anfänglichen DNA‐Modellen zu einer Reihe von interessanten, jedermann zugänglichen Konzepten verliefen – und das ist charakteristisch für Innovationen – alles andere als geradlinig.
Nanopartikel zur Rettung von Maya‐Kulturschätzen
Authors: Groß Michael
Published: February 2011

Wandmalereien hat man im 20. Jahrhundert gern zu ihrem Schutz mit Kunststoff versiegelt, doch inzwischen haben Forscher herausgefunden, dass solche Maßnahmen oft mehr schaden als nutzen. Eine neue Lösung bieten Nanopartikel aus Calcium‐ und Bariumhydroxid.
Surface functionalization of superparamagnetic nanoparticles for the development of highly efficient magnetic resonance probe for macrophages
Authors: Huang Chao , Neoh Koon Gee , Wang Liang , Kang En‐Tang , Shuter Borys
Published: February 2011

In vivo magnetic resonance imaging (MRI) tracking of macrophages plays an important role in monitoring and understanding numerous human diseases with high macrophage activity. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) of ∼12 nm were surface‐functionalized with poly(DL‐lactic acid‐co‐malic acid) copolymer (PLMA) via a nanoprecipitation method. The r1, r2 and r2/r1 values of the PLMA‐SPIONs obtained at a magnetic field of 3 T were 0.38, 196 and 516 mM−1 s−1, respectively. The high r2/r1 ratio can be expected to provide enhanced MR contrast. The PLMA‐SPIONs were readily taken in by macrophages and the high iron uptake was confirmed via Prussian Blue staining and quantified by inductively coupled plasma mass spectrometry (ICP‐MS). No significant cytotoxicity was found even at a high nanoparticle loading of 67.7 pg Fe per cell. A linear relationship between R2 and R values and the number of PLMA‐SPIONs labeled cells was observed in vitro. As a result of the significantly higher R than R2 effects, an in vitro detection threshold of about 2820 labeled cells was achieved with short labeling time and low nanoparticle concentration using a clinical 3 T MRI scanner. Thus, the PLMA‐SPIONs can be potentially useful as magnetic resonance probes for targeting and tracking macrophages. Copyright © 2011 John Wiley & Sons, Ltd.
Structure, microstructure and magnetic properties of mixed rare earth oxide (Dy1‐xErx)2O3
Authors: Heiba Z. K. , Bakr Mohamed M. , Abdelslam M. A. , Fuess L. H.
Published: February 2011

The mixed rare earth oxide (Dy1‐xErx)2O3 (0.0 ≤ x ≤ 1.0) were synthesized by a sol–gel process. X‐ray and neutron diffraction data were collected and crystal structure and microstructure analyses were performed using Rietveld refinement method. All samples were found to have the same crystal structure and formed solid solutions over the whole range of x. Preferential cationic distribution is found for all samples but with different extent with Dy3+ preferring the 8b among the two non‐equivalent sites 8b and 24d of the space group Ia3. The lattice parameter is found to vary linearly with the composition x and a systematic variation is found in the r.m.s microstrain $ \langle \epsilon^2_{\rm L} \rangle^{1/2} $. Magnetization measurements were done in the temperature range 5‐300 K and a behavior in accordance with Curie‐Weiss law was found. Anomalous concentration dependence is found in magnetic susceptibility which is ascribed to the concentration dependence of effective crystal field combined with the contribution of 4I15/2 and 6H15/2 manifold at elevated temperature. The effective magnetic moments μeff is found to decrease linearly with composition parameter x, except for sample x=0.5 where the magnetization is enhanced. The Curie‐Weiss paramagnetic temperatures indicated antiferromagnetic interaction. These magnetic results are discussed in view of the cationic distribution. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel chemiluminescence quenching method for determination of sulfonamides in pharmaceutical and biological fluid based on luminol–Ag(III) complex reaction in alkaline solution
Authors: Sun Hanwen , Chen Peiyun , Li Liqing , Cheng Peng
Published: February 2011

A novel chemiluminescence (CL) quenching method for the determination of sulfonamides is proposed. The CL reaction between Ag(III) complex [Ag(HIO6)2]5− and luminol in alkaline solution was investigated. The quenching effect of sulfonamides on CL emission of [Ag(HIO6)2]5−–luminol system was found. Quenching degree of CL emission was proportional to sulfonamide concentration. The effects of the reaction conditions on CL emission and quenching were examined. Under optimal conditions, the detection limits (s/n = 3) were 7.2, 17 and 8.3 ng/mL for sulfadiazine, sulfameter, and sulfadimethoxine, respectively. The recoveries of the three drugs were in the range of 91.3–110% with RSDs of 1.9–2.7% for urine samples, and 106–112% with RSDs of 1.6–2.8% for serum samples. The proposed method was used for the determination of sulfadiazine at clinically relevant concentrations in real urine and serum samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.
Spectral data analyses and structure elucidation of metoprolol tartrate
Authors: Qiao Jun‐qin , Wang Ya‐qin , Liu Chen‐chen , Zhu Wei , Lian Hong‐zhen , Ge Xin
Published: February 2011

The infrared spectrum, ultraviolet spectrum, mass spectra, and nuclear magnetic resonance spectra of metoprolol tartrate, an antiarrhythmic medicine, were reported and interpreted comprehensively. The vibrations of functional groups in infrared spectrum, electron transitions in ultraviolet spectrum, and main characteristic fragmentations in mass spectra of metoprolol tartrate were discussed. All the 1H and 13C NMR chemical shifts were assigned by means of distoritionless enhancement by polarization transfer‐135 and ‐90, 1H‐1H correlation spectroscopy, and 13C‐1H correlation spectroscopy via short‐ and long‐range coupling. Copyright © 2011 John Wiley & Sons, Ltd.
Spatiotemporal changes in cell adhesiveness during vertebrate limb morphogenesis
Authors: Wada Naoyuki
Published: February 2011

During vertebrate limb development, various molecules are expressed in the presumptive limb field or the limb bud in a spatiotemporal‐specific manner. The combination of these molecules regulates cellular properties that affect limb initiation and its morphogenesis, especially cartilage formation. Cell adhesiveness of the limb mesenchyme is a key factor in the regulation of cell distribution. Differential adhesiveness of mesenchymal cells is first observed between cells in the presumptive limb field and flank region, and the adhesiveness of the cells in the limb field is higher than that of cells in the flank region. In the limb bud, the adhesiveness of mesenchymal cells shows spatiotemporal difference, which reflects the positional identity of the cells. Position‐dependent cell adhesiveness is also observed in blastema cells of the regenerating limb. Therefore, local changes in cell adhesiveness are observed during limb development and regeneration, suggesting significant roles for cell adhesiveness in limb morphogenesis. Developmental Dynamics 240:969–978, 2011. © 2011 Wiley‐Liss, Inc.
Looking proximally and distally: 100 years of limb regeneration and beyond
Authors: Stocum David L. , Cameron Jo Ann
Published: February 2011

The experimental study of amphibian limb regeneration spans most of the 20thcentury and the first decade of the 21stcentury. We first review the major questions investigated over this time span: (1) the origin of regeneration blastema cells, the mechanism of tissue breakdown that liberates cells from their tissue organization to participate in blastema formation, (3) the mechanism of dedifferentiation of these cells, (4) how the blastema grows, (5) how the blastema is patterned to restore the missing limb structures, and (6) why adult anurans, birds and mammals do not have the regenerative powers of urodele salamanders. We then look forward in a perspective to discuss the many unanswered questions raised by investigations of the past century, what new approaches can be taken to answer them, and what the prospects are for translation of basic research on limb regeneration into clinical means to regenerate human appendages. Developmental Dynamics 240:943–968, 2011. © 2011 Wiley‐Liss, Inc.
Expression of key retinoic acid modulating genes suggests active regulation during development and regeneration of the amphibian limb
Authors: McEwan James , Lynch Joshua , Beck Caroline W.
Published: February 2011

We have previously shown differential regulation of components of the Retinoic acid (RA) pathway in Xenopus tadpole hindlimb regeneration. RA is thought to act as a morphogen, providing positional information during development and regeneration. We have investigated the regulation of genes involved in RA synthesis, catabolism, and binding in developing and regenerating Xenopus limbs. Our data indicate that RA is synthesised by Raldh2 in proximal cells during limb bud outgrowth. Furthermore, Cyp26b is expressed transiently in the progress zone of developing limbs and the blastema of regenerating limbs suggesting degradation of RA occurs in both processes. The RA‐binding protein Crabp2 is also upregulated during regeneration. We summarise this data to predict the presence of evolving gradients of RA in the developing amphibian limb. Thus, RA from the stump cells could be responsible for the establishment of proximal‐distal pattern during limb regeneration, as predicted by classical studies. Developmental Dynamics 240:1259–1270, 2011. © 2011 Wiley‐Liss, Inc.
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

Based 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

Recent 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

Pyroglutamic 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

A 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

Research 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

The 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

For 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

A 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

The 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

In 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

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

Microstructure 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

Nano‐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

Currently, 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

Bacterial 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

Cellulose 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

This 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.
Porous hydroxyapatite and gelatin/hydroxyapatite microspheres obtained by calcium phosphate cement emulsion
Authors: Perez Roman A. , Del Valle Sergio , Altankov George , Ginebra Maria‐Pau
Published: February 2011

Hydroxyapatite and hybrid gelatine/hydroxyapatite microspheres were obtained through a water in oil emulsion of a calcium phosphate cement (CPC). The setting reaction of the CPC, in this case the hydrolysis of α‐tricalcium phosphate, was responsible for the consolidation of the microspheres. After the setting reaction, the microspheres consisted of an entangled network of hydroxyapatite crystals, with a high porosity and pore sizes ranging between 0.5 and 5 μm. The size of the microspheres was tailored by controlling the viscosity of the hydrophobic phase, the rotation speed, and the initial powder size of the CPC. The incorporation of gelatin increased the sphericity of the microspheres, as well as their size and size dispersion. To assess the feasibility of using the microspheres as cell microcarriers, Saos‐2 cells were cultured on the microspheres. Fluorescent staining, SEM studies, and LDH quantification showed that the microspheres were able to sustain cell growth. Cell adhesion and proliferation was significantly improved in the hybrid gelatin/hydroxyapatite microspheres as compared to the hydroxyapatite ones. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.