bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma surface modification and characterization of collagen‐based artificial cornea for enhanced epithelialization
Authors: Rafat Mehrdad , Griffith May , Hakim Malik , Muzakare Lea , Li Frank , Khulbe K.C. , Matsuura Takeshi
Published: July 2007

Argon plasma treatment enhanced the attachment of epithelial cells to a collagen‐based artificial cornea crosslinked using glutaraldehyde (GA) and glutaraldehyde‐polyethylene oxide dialdehyde (GA‐PEODA) systems. The epithelialization of untreated and treated surfaces was evaluated by the seeding and growth of human corneal epithelial cells. Characterization of polymer surface properties such as surface hydrophilicity and roughness was also made by contact angle measurement and atomic force microscopy, respectively. Contact angle analysis revealed that the surface hydrophilicity significantly increased after the treatment. In addition, AFM characterization showed an increase in surface roughness through argon plasma treatment. Based on the biological and surface analysis, argon plasma treatment displays promising potential for biocompatibility enhancement of collagen‐based artificial corneas. It was also found that the cell attachment to artificial cornea surfaces was influenced by the combined effects of surface chemistry (i.e., surface energy), polymer surface morphology (i.e., surface roughness), and polar interactions between functional groups at the polymer surface and cell membrane proteins. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis, X‐ray Structure, and Pharmacological Activity of Some 6,6‐Disubstituted Chromeno[4,3‐b]‐ and Chromeno‐ [3,4‐c]‐quinolines
Authors: Hegab Mohamed I. , Abdel‐Fattah Abdel‐Samee M. , Yousef Nabil M. , Nour Hany F. , Mostafa A. M. , Ellithey Mohey
Published: July 2007

Some chromeno[4,3‐b]quinolines 4a–i were obtained from β‐chloro carboxyaldehydes 3a–c with different aniline derivatives namely, aniline, 4‐fluoroaniline, and 2‐aminophenol. Surprisingly, 3a–c reacted with 2‐aminothiophenol and afforded the chromeno[3,4‐c]quinoline derivatives 5a–c. Single‐crystal X‐ray diffraction studies of 4e and 5b provided good support for the established structure. Compounds 4b and 5b showed significant anti‐inflammatory and ulcerogenic score activities compared to that of indomethacin.
Functional Organogel Based on a Salicylideneaniline Derivative with Enhanced Fluorescence Emission and Photochromism
Authors: Xue Pengchong , Lu Ran , Chen Guojun , Zhang Yuan , Nomoto Hiroyuki , Takafuji Makoto , Ihara Hirotaka
Published: July 2007

A new organogelator based on a salicylideneaniline derivative with cholesterol moieties was synthesized, and it was proposed that it could gelate various organic solvents, such as 1‐butanol, 1‐octanol, butyl acetate, tetrachloromethane, benzene, toluene through combination with a gelation test. From the results of analysis by UV/Vis absorption, circular dichroism (CD), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies and semiempirical (AM1) calculations, we believed that the gelator molecules could self‐assemble into left‐handed helical nanofibers through unimolecular layer packing, which further twisted into the thicker fibers and constructed 3D networks in the gel phase. Interestingly, the organogel exhibited strong fluorescence enhancement relative to a solution of the same concentration because of the formation of J aggregations. Meanwhile, photochromism of the organogel could take place under UV‐light irradiation. Both strong fluorescence emission and photochromism properties were concurrent in one system based on a salicylideneaniline derivative. It was suggested that the self‐assembly of the functional organogelator could lead to unique photophysical properties.
Chelation‐Mediated Aqueous Synthesis of Metal Oxyhydroxide and Oxide Nanostructures: Combination of Ligand‐Controlled Oxidation and Ligand‐Cooperative Morphogenesis
Authors: Oaki Yuya , Imai Hiroaki
Published: July 2007

We have synthesized nanostructures of iron and cobalt oxyhydroxides and manganese oxides in aqueous solution containing a chelating agent. Nanosheets of FeOOH and NaxMnO2 and nanoflakes of CoOOH were generated from the corresponding divalent metal salts and ethylenediaminetetraacetate (EDTA) by one‐pot synthesis under ambient conditions. The chelating agent fulfilled multiple roles in the reaction process and morphogenesis leading to two‐dimensional nanostructures. Coordination to the divalent metal ions inhibited rapid precipitation of metal hydroxides and mediated oxidation to tri‐ and tetravalent species by dissolved oxygen. Along with the deposition, the two‐dimensional and single‐crystal nanostructures were also associated with interactions of the chelating agent. Therefore, this approach can be regarded as a combination of ligand‐controlled oxidation and ligand‐cooperative morphogenesis. Parallel control of the reaction and the morphology was achieved by a simple approach. The model cases suggest that tailoring chelation can facilitate the design of other metal oxide nanomaterials.
Enantioselective Radical Cyclizations: A New Approach to Stereocontrol of Cascade Reactions
Authors: Miyabe Hideto , Takemoto Yoshiji
Published: July 2007

Stereocontrol in a cascade radical addition–cyclization–trapping reaction was achieved by a new approach, which utilizes a hydroxamate ester moiety as a coordinating chiral Lewis acid tether between two radical acceptors. A remarkable feature of this reaction is the construction of three bonds and tertiary and quaternary stereogenic centers through both inter‐ and intramolecular carbon–carbon bond‐forming processes. The chiral Lewis acid mediated reaction of oxime ethers also proceeded smoothly with good enantio‐ and diastereoselectivities, indicating the usefulness of the cascade approach for the asymmetric synthesis of various γ‐lactams.
Gerät zur Charakterisierung des Feinstaubpotenzials von Straßenoberflächen
Authors: El‐Waraki M. S. , Schmidt E.
Published: July 2007

Aufwirbelung von abgelagerten Feinstäuben kann erheblich zur Immissionsbelastung beitragen. Ein im Fachgebiet Sicherheitstechnik/Umweltschutz entwickeltes Gerät nimmt auf der Straßenoberfläche befindenden Staub durch eine Luftströmung auf. Der dabei aufgewirbelte Staubanteil wird hinsichtlich Größe und Anzahl der Partikeln on‐line charakterisiert. Somit wird es möglich, den Untergrund in Bezug auf eine mögliche Aufwirbelung von Feinstaub zu beschreiben.
Fluiddynamik und Wärmeübergang bei der Fallfilmverdampfung von Reinstoffen mit hohen Prandtl‐Zahlen
Authors: Weise F. , Scholl S.
Published: July 2007

Die derzeitigen Berechnungsgrundlagen für Fluiddynamik und Wärmeübergang in Fallfilmverdampfern basieren vornehmlich auf Experimenten mit Reinstoffen oder Gemischen bei vergleichsweise niedrigen Viskositäten. Insbesondere für Systeme mit hohen Prandtl‐Zahlen wurden praktisch ausschließlich wässrige Mischungen betrachtet. Auf Basis eigener experimenteller Untersuchungen mit viskosen organischen Reinstoffen wird ein Beitrag zum Verständnis der gekoppelten Vorgänge von Strömung und Wärmeübertragung in einem innen berieselten Verdampferrohr geleistet. In diesem Zusammenhang wird das Auftreten erster Blasen am Übergang von der Oberflächenverdampfung zum Blasensieden in Abhängigkeit stofflicher Parameter für viskose Flüssigkeiten eingehend untersucht. Mit dem Auftreten der Blasen geht ein deutlicher Anstieg des Wärmeübergangs einher ohne jedoch Filminstabilitäten zu induzieren. Eine erste Modellierung ist zwar für den jeweiligen Stoff möglich, jedoch nicht auf andere Flüssigkeiten übertragbar.
Untersuchungen zu Struktur‐Eigenschaftsbeziehungen an porösen Elektroden für implantierbare Li/MnO2‐Batterien
Authors: Hucke Th. , Drews J. , Traulsen T. , Staub R. , Fehrmann G. , Stintz M. , Gabsch St.
Published: July 2007

Für die Energieversorgung medizinischer Implantate werden seit mehreren Jahren Lithium/Mangandioxid‐Primärbatterien eingesetzt. Die Leistungsfähigkeit der Batterie wird dabei maßgeblich durch die Struktur der porösen Kathode bestimmt. Diese kompaktierte Feststoffelektrode enthält als elektrochemisch aktives Material Mangandioxid (MnO2) sowie weitere pulverförmige Additive. Durch Fraktionierung des Aktivmaterials kann die Struktur der Kathode gezielt beeinflusst werden. Verringert man die mittlere Partikelgröße eines Pulversystems, vergrößert sich die spezifische Oberfläche, zudem werden Diffusionswege für Lithiumionen innerhalb des Einzelpartikels verkürzt. Es ist jedoch bekannt, dass bei Verringerung der Partikelgröße die Oberflächenkräfte dominieren und zu einer verstärkten Agglomerationsneigung des Pulvers führen. Hieraus resultieren Kathoden mit höherer Porosität aber geringerer Packungsdichte. Mit zunehmender mittlerer Partikelgröße können größere Packungsdichten erreicht werden, was zur Verbesserung der Aktivmassebeladung und der Energiedichte der Batterie beiträgt. Die vorgestellte Untersuchung beschäftigt sich mit den Einflüssen der Partikelgrößenverteilung der Aktivmasse auf die Struktur der Kathode und die hieraus resultierenden Eigenschaften von Primärbatterien. Entgegen dem Stand der Technik konnte der positive Einfluss der Partikelgrößenverringerung des Aktivmaterials für die hier untersuchten Batterietypen nicht bestätigt werden.
Herstellung sphärischer Naphthalinpellets durch Abtropfen in eine wässrige Phase
Authors: Krautwald J. , Schnitzlein K. , Vorlop K.‐D.
Published: July 2007

Für die Anwendung der Naphthalinsublimation in einer Thermowaage werden kugelförmige Naphthalinpellets als repräsentativer Katalysatorersatz benötigt. Zur Herstellung dieser Pellets wird hier eine alternative Methode vorgestellt. Unter Ausnutzung von Kapillar‐ und Oberflächenkräften werden Pellets bei Umgebungsdruck und geringem technischem Aufwand generiert.
Gasunterstützte Ölsaat‐Pressung
Authors: Voges S. , Eggers R. , Pietsch A.
Published: July 2007

Die in den letzten Jahren wachsende Bedeutung von Ölsaaten wie Raps und Soja unter anderem als alternative Kraftstoffquellen macht eine Effizienzsteigerung der Fest/Flüssig‐Trennung zunehmend interessant. Herkömmlich wird die Speiseölgewinnung durch eine kontinuierliche Lösungungsmittelextraktion mit Hexan vorgenommen, der eine mechanische Fest/Flüssig‐Trennung auf einer Schneckenpresse vorgeschaltet sein kann. Bei dem neuen Verfahren der gasunterstützten Pressung handelt es sich um eine mechanische Fest/Flüssig‐Trennung unter Zuhilfenahme eines verdichteten Gases. Dieses Gas ist bevorzugt CO2 und wird vor oder während der Pressung mit der Ölsaat in Kontakt gebracht, um so einen verbesserten Abpressgrad zu erreichen. Die Effizienz dieses Verfahrens konnte in eigenen Experimenten nachgewiesen werden. Die Vorteile sind die Ausbeuteerhöhung sowie der denkbare völlige Verzicht auf konventionelle brennbare Lösungsmittel bei der Gewinnung vegetabiler Öle.
Valproic acid for the treatment of myeloid malignancies
Authors: Kuendgen Andrea , Gattermann Norbert
Published: July 2007

Valproic acid (VPA) has been used as an anticonvulsant for decades. Recently, it was demonstrated that VPA also acts as a histone deacetylase inhibitor and induces differentiation and apoptosis in a variety of malignant cells in vitro. The effect of VPA on tumor cells differs according to cell type, degree of differentiation, and underlying genetic alterations. Clinical trials with VPA have focused on acute myeloid leukemia and the myelodysplastic syndromes. When it was used as monotherapy or in combination with all‐trans retinoic acid, which synergizes in vitro, VPA achieved hematologic improvement in a subset of patients. Similar to other inhibitors of histone deacetylases, complete or partial remissions rarely were observed. In this report, the authors reviewed the in vitro and in vivo data obtained with VPA, and they considered possible combination regimens aimed at improving therapeutic efficacy. Cancer 2007. © 2007 American Cancer Society.
Association between megestrol acetate treatment and symptomatic adrenal insufficiency with hypogonadism in male patients with cancer
Authors: Dev Rony , Del Fabbro Egidio , Bruera Eduardo
Published: July 2007

Patients with advanced cancer may develop cachexia, which is often treated with megestrol acetate (MA). In addition to thromboembolic disease, MA may cause symptomatic suppression of the hypothalamic pituitary adrenal axis. In male patients with cancer, treatment with MA may also suppress the gonadal axis, resulting in symptomatic androgen deficiency. Three cases are presented to highlight the symptomatic burden of adrenal insufficiency and hypogonadism. Clinicians need an increased awareness of the complication of adrenal insufficiency secondary to MA treatment and a low threshold to test for adrenal and gonadal dysfunction in symptomatic male patients with advanced cancer. Cancer 2007. © 2007 American Cancer Society.
Calculation of EPR g Tensors for Transition‐Metal Complexes Based on Multiconfigurational Perturbation Theory (CASPT2)
Authors: Vancoillie Steven , Malmqvist Per‐Åke , Pierloot Kristine
Published: July 2007

The computation of the electronic g tensor by two multireference methods is presented and applied to a selection of molecules including CN, BO, AlO, GaO, InO, ZnH, ZnF, O2, H2O+, O3−, and H2CO+ (group A) as well as TiF3, CuCl42−, Cu(NH3)42+, and a series of d1‐MOX4n− compounds, with M=V, Cr, Mo, Tc, W, Re and X=F, Cl, Br (group B). Two approaches are considered, namely, one in which spin–orbit coupling and the Zeeman effect are included using second‐order perturbation theory and another one in which the Zeeman effect is added through first‐order degenerate perturbation theory within the ground‐state Kramers doublet. The two methods have been implemented into the MOLCAS quantum chemistry software package. The results obtained for the molecules in group A are in good agreement with experiment and with previously reported calculated g values. The results for the molecules in group B vary. While the g values for the d1 systems are superior to previous theoretical results, those obtained for the d9 systems are too large compared to the experimental values.
X‐Ray Spectroscopic and Diffraction Study of the Structure of the Active Species in the NiII‐Catalyzed Polymerization of Isocyanides
Authors: Metselaar Gerald A. , Schwartz Erik , de Gelder René , Feiters Martin C. , Nikitenko Serge , Smolentsev Grigory , Yalovega Galina E. , Soldatov Alexander V. , Cornelissen Jeroen J. L. M. , Rowan Alan E. , Nolte Roeland J. M.
Published: July 2007

The structure of the active complex in the Ni‐catalyzed polymerization of isocyanides to give polyisocyanides is investigated. It is shown by X‐ray absorption spectroscopy (XAS), including EXAFS (extended X‐ray absorption fine structure) and XANES (X‐ray absorption near edge structure), and single‐crystal X‐ray diffraction, to contain a carbene‐like ligand. This is the first structural characterization of a crucial intermediate in the so‐called merry‐go‐round mechanism for Ni‐catalyzed isocyanide polymerization.
Do weak phonological representations impact on arithmetic development? A review of research into arithmetic and dyslexia
Authors: Simmons Fiona R. , Singleton Chris
Published: July 2007

We review significant empirical studies of the arithmetic abilities of children with dyslexia. These studies suggest that the academic impairments of children with dyslexia are not limited to reading and spelling, but also include aspects of mathematics. A consistent finding across a number of studies is that children with dyslexia have difficulty recalling number facts. The results of the reviewed studies are analysed, both in terms of the weak phonological representations hypothesis, and the triple‐code theory of mathematical cognition. It is suggested that the phonological processing deficits of individuals with dyslexia impair aspects of mathematics that rely on the manipulation of verbal codes (e.g. counting speed, number fact recall), whilst other aspects of mathematics that are less reliant on verbal codes (e.g. estimation, subitising) are unimpaired. Suggestions for testing this hypothesis are put forward. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of electromagnetic scattering from conducting polygons by the point matching method
Authors: Ohnuki Shinichiro , Ohtaka Noriaki , Hinata Takashi
Published: July 2007

A region decomposition technique is proposed for point matching method analysis of electromagnetic scattering problems involving various polygonal cylinders with conducting edges. In this paper, it is verified that the scattering problem is amenable to accurate numerical analysis by the point matching method. The influence of the shape change of the scatterer in the shadow region is investigated. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(8): 18–25, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20339
Performance improvement of InGaAs quantum well distributed Bragg reflector laser with curved grating
Authors: Uemukai Masahiro , Nozu Shunsuke , Suhara Toshiaki
Published: July 2007

Performance improvement is performed for an InGaAs quantum well DBR laser consisting of a ridge active channel and a curved grating such that single‐mode oscillation with high efficiency and high spectral purity can be realized. The waveguide absorption loss is substantially reduced by selectively disordering the quantum well in the DBR region. The curved DBR grating is optimized so that a high reflectivity and sharp wavelength selectivity are obtained simultaneously. In addition, the external differential quantum efficiency is enhanced by optimizing the reflectivity at the output end with a low‐reflection coating. In this approach, a single‐mode oscillation is realized with a high external differential quantum efficiency of 0.79 and a side mode suppression ratio of 50 dB. In the laser with a window structure near the output end, resistance to catastrophic optical damage is significantly improved and the maximum output is 294 mW. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(8): 1– 7, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20348
A low‐power design method for FPGA using extra flip‐flops driven by phase‐shifted clock
Authors: Katashita Toshihiro , Maeda Atsushi , Yamaguchi Yoshinori
Published: July 2007

Low‐power design is important for extending the life of batteries and chips and simplifying cooling systems. In this paper, a low‐power design method for FPGA using extra flip‐flops is presented. Each of the extra flip‐flops is driven by a phase‐shifted clock, which makes the application of this method easier. We tested our method on an AES circuit, a DES circuit, an 8‐bit multiplier, and a 16‐bit multiplier. Power consumption reductions of up to 70.67, 15.69, 4.43, and 28.54%, respectively, were achieved. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(8): 35–44, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20376
Poly(methimazolyl)borate Alkyne Complexes of Molybdenum and Tungsten
Authors: Hill Anthony F. , Tshabang Never , Willis Anthony C.
Published: July 2007

Synthetic routes are reported to complexes of the form [MI(alkyne)(CO){HnB(mt)4–n}] (mt = methimazolyl; n = 1, 2; M = Mo, W) through the reactions of alkyne complexes [WI2(HC≡CSiMe3)2(CO)2] or [MI2(RC≡CR)2(NCMe)(CO)] (M = Mo, W; R = Me, Ph) with the salts Na[HnB(mt)4–n].The derivative [MoI(PhC≡CPh)(CO){HB(mt)3}] reacts with Na[HB(mt)3] to provide the complex [Mo(PhC≡CPh)(CO){HB(mt)3}2] in which the two HB(mt)3 ligands adopt different non‐interconverting coordination modes, κ3‐S,S′,S″ and κ1‐S. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Comparison of hepatic properties and transplantation of Thy-1+ and Thy-1− cells isolated from embryonic day 14 rat fetal liver
Authors: Oertel Michael , Menthena Anuradha , Chen Yuan-Qing , Shafritz David A.
Published: July 2007

Thy-1, a marker of hematopoietic progenitor cells, is also expressed in activated oval cells of rat liver. Thy-1+ cells are also in rat fetal liver and exhibit properties of bipotent hepatic epithelial progenitor cells in culture. However, no information is available concerning liver repopulation by Thy-1+ fetal liver cells. Therefore, we isolated Thy-1+ and Thy-1− cells from embryonic day (ED) 14 fetal liver and compared their gene expression characteristics

in vitro

and proliferative and differentiation potential after transplantation into adult rat liver. Fetal liver cells selected for Thy-1 expression using immunomagnetic microbeads were enriched from 5.2%-87.2% Thy-1+. The vast majority of alpha fetoprotein+, albumin+, cytokine-19+, and E-cadherin+ cells were found in cultured Thy-1− cells, whereas nearly all CD45+ cells were in the Thy-1+ fraction. In normal rat liver, transplanted Thy-1+ cells produced only rare, small DPPIV+ cell clusters, very few of which exhibited a hepatocytic phenotype. In retrorsine-treated liver, transplanted Thy-1+ fetal liver cells achieved a 4.6%-23.5% repopulation. In contrast, Thy-1− fetal liver cells substantially repopulated normal adult liver and totally repopulated retrorsine-treated liver. Regarding the stromal cell–derived factor (SDF)–1/chemokine (C-X-C motif) receptor 4 (CXCR4) axis for stem cell homing, Thy-1+ and Thy-1− fetal hepatic epithelial cells equally expressed CXCR4. However, SDF-1α expression was augmented in bile ducts and oval cells in retrorsine/partial hepatectomy–treated liver, and this correlated with liver repopulation by Thy-1+ cells.

Conclusion:

Highly enriched Thy-1+ ED14 fetal liver cells proliferate and repopulate the liver only after extensive liver injury and represent a fetal hepatic progenitor cell population distinct from Thy-1− stem/progenitor cells, which repopulate the normal adult liver. (HEPATOLOGY 2007.)
Clevudine is highly efficacious in hepatitis B e antigen-negative chronic hepatitis B with durable off-therapy viral suppression
Authors: Yoo Byung Chul , Kim Ju Hyun , Kim Tae-Hun , Koh Kwang Cheol , Um Soon-Ho , Kim Young Soo , Lee Kwan Sik , Han Byung Hoon , Chon Chae Yoon , Han Joon-Yeol , Ryu Soo Hyung , Kim Haak Cheoul , Byun Kwan Soo , Hwang Seong Gyu , Kim Byung-Ik , Cho Mong , Yoo Kwon , Lee Heon-Ju , Hwang Jae Seok , Kim Yun Soo , Lee Young-Suk , Choi Sung-Kyu , Lee Youn-Jae , Yang Jin-Mo , Park Joong-Won , Lee Myung-Seok , Kim Dae-Ghon , Chung Young-Hwa , Cho Se-Hyun , Choi Jong-Young , Kweon Young-Oh , Lee Heon Young , Jeong Sook-Hyang , Yoo Hee-Won , Lee Hyo-Suk
Published: July 2007

Clevudine is a pyrimidine analog with potent and sustained antiviral activity against HBV. In the present study, we evaluated the safety and efficacy of clevudine 30 mg daily for 24 weeks and assessed the durability of antiviral response for 24 weeks after cessation of dosing in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (e-CHB). We randomized a total of 86 patients (3:1) to receive clevudine 30 mg (n = 63) or placebo (n = 23) daily for 24 weeks. We followed patients for an additional 24 weeks after withdrawal of treatment. The median changes in HBV DNA from baseline were −4.25 and −0.48 log10 copies/mL at week 24 in the clevudine and placebo groups, respectively (

P

< 0.0001). Viral suppression in the clevudine group was sustained after withdrawal of therapy, with 3.11 log10 reduction at week 48. At week 24 and week 48, 92.1% and 16.4% of patients in the clevudine group had undetectable serum HBV DNA levels by Amplicor PCR assay (<300 copies/mL). The proportion of patients who achieved ALT normalization was 74.6% and 33.3% in the clevudine and placebo groups at week 24, respectively (

P

= 0.0006). ALT normalization in the clevudine group was well-maintained during the post-treatment follow-up period. The incidence of adverse events was similar in the 2 groups. No resistance to clevudine was detected during treatment.

Conclusion:

A 24-week clevudine therapy was well-tolerated and showed potent and sustained antiviral effect without evidence of viral resistance in e-CHB patients. However, treatment for longer than 24 weeks would be needed to achieve durable remission. (HEPATOLOGY 2007.)
Surface property and in vitro biodegradation of microspheres fabricated by poly(ε‐caprolactone‐b‐ethylene oxide) diblock copolymers
Authors: Yu Guoqiang , Zhang Yu , Shi Xudong , Li Zhanshuang , Gan Zhihua
Published: July 2007

Microspheres fabricated by biodegradable polymers with tunable surface properties show great potentials as microcarriers in in vitro cell cultivation and tissue engineering. Herein we reported a new method to regulate the surface property and morphology of microspheres via the synthesis of biodegradable amphiphilic block copolymers with adjustable compositions. The poly(ϵ‐caprolactone‐b‐ethylene oxide) diblock copolymers with functional amino end groups bonding to the PEO block (PCL‐b‐PEO‐NH2) were synthesized by sequential ring‐opening polymerization with potassium bis(trimethylsilyl) amide as initiator. The copolymers were characterized by gel permeation chromatography (GPC) and 1H NMR, and then used to fabricate microspheres by w/o/w double emulsion solvent evaporation technique. The surface properties of microspheres were studied by means of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The results indicated that both the fabrication conditions and copolymer composition have great influences on the surface morphology and property of microspheres. The reactive amino functional groups are dominantly located on the surface of microspheres. The in vitro degradation of microspheres was studied by following the morphological changes of microspheres. The influences of hydrophilic PEO out‐layers on the enzymatic degradation of microspheres were discussed. These microspheres with controllable surface morphology and amino functional groups are expected to be promising alternatives for the further biomimetic modification to promote cell growth on materials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Bioactive and degradable hybridized nanofibers of gelatin–siloxane for bone regeneration
Authors: Song Ju‐Ha , Yoon Byung‐Ho , Kim Hyoun‐Ee , Kim Hae‐Won
Published: July 2007

Organic–inorganic hybridized nanofibers constituted of gelatin and siloxane were generated by the electrospinning technique for use as bone regeneration matrices. The composition of the nanofibers selected was to be both degradable and bioactive. Precursors of gelatin and siloxane were dissolved in a modified acidic solvent composed of acetic acid, ethyl acetate, and distilled water. The hybridized nanofibers with various compositions (gelatin/siloxane = 1/2, 1, and 2 by weight fraction) were successfully electrospun under the adjusted processing conditions. Compared to the pure gelatin nanofiber, the hybridized nanofibers showed improved chemical stability in a saline solution. This was attributed to the cross‐linking effect of the siloxane with the gelatin chains. Osteoblastic cells were observed to attach, spread, and populate actively on the hybridized nanofiber matrices. In particular, the cells on the hybridized nanofibers were recruited to elicit better osteoblastic activity (alkaline phosphatase) with respect to those on the pure gelatin. The newly‐developed hybridized nanofiber is considered to be useful as a bone regeneration matrix, due to its nanofibrous structural trait as well as its degradability and bone cell activity. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Design of bioinspired polymeric materials based on poly(D,L‐lactic acid) modifications towards improving its cytocompatibility
Authors: Niu Xufeng , Luo Yanfeng , Li Yonggang , Fu Chunhua , Chen Jia , Wang Yuanliang
Published: July 2007

To design novel bioinspired polymeric material, poly(D,L‐lactic acid) (DL‐PLA) was on the base and modified in the bulk. Firstly, maleic anhydride (MA) groups were introduced to the side chain of DL‐PLA by the way of melting free radical copolymerization using benzoyl peroxide as an initiator. Then, to neutralize the acid generated during DL‐PLA degradation, aliphatic diamine was immobilized by the N‐acylation of anhydrides with butanediamine. As the following stage, adhesive peptides Arg‐Gly‐Asp‐Ser (RGDS) were grafted into the backbone of DL‐PLA by using carbodiimide as a coupling agent, in order to endow DL‐PLA with bioactivity and biospecificity. The characterizations of the obtained polymers were by the means of GPC‐MALLS, FTIR, 13C NMR and XPS to explore the structures and rhodamine‐carboxyl interaction method, ninhydrin reaction and amino acid analyzer to determine the content of MA, butanediamine, and RGDS, respectively, followed the test of pH changes during degradation in distilled water (pH = 6.45). Finally, the osteoblast behavior on different DL‐PLA based films was investigated and the results indicated that the introduction of diamine could promote cell attachment and viability, and the incorporation of RGDS further improved its cytocompatibility. The synthetic DL‐PLA based bioinspired material may have potentials for tissue engineering and other biomedical applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Photopolymerization and shrinkage kinetics of in situ crosslinkable N‐vinyl‐pyrrolidone/poly(ε‐caprolactone fumarate) networks
Authors: Sharifi Shahriar , Mirzadeh Hamid , Imani Mohammad , Atai Mohammad , Ziaee Farshid
Published: July 2007

Biodegradable, injectable and in situ photocrosslinkable macromers based on fumaric acid and polycaprolactone (PCLF) were prepared and characterized by FTIR, 1HNMR, and 13CNMR spectroscopy. The multifunctional macromers dissolved in N‐vinyl pyrollidone (NVP) were photopolymerized by visible light irradiation in the presence of camphorquinone as photoinitiator. The photocrosslinking reaction was monitored by measuring shrinkage strain and shrinkage strain rate. The degree of photopolymerization reaction i.e. degree of conversion (DC%) was traced using FTIR spectroscopy. A three level factorial design was developed to study the effects of initiator concentration, NVP concentration, and molecular weight of PCLF upon photocrosslinking characteristics including degree of conversion and shrinkage strain. Results revealed that although neat PCLF was photopolymerized, but it was putty like after 220 seconds of irradiation and showed a very low degree of conversion (29%). Adding about 20% NVP caused a dramatic increase in its degree of conversion (63.33%). Increasing NVP up to 50% resulted in a decrease in DC% because of lower reactivity of NVP and leaving more unreacted NVP monomers. Sol fraction studies supported these results indicating that at higher NVP concentration, most of NVP and PCLF have not undergone the crosslinking reaction, leading to 55% decrease in DC%. Shrinkage strain measurement also confirmed the FTIR results. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Potential use of cholecalciferol polyethylene glycol succinate as a novel pharmaceutical additive
Authors: Zhao H. Z. , Tan E. C. , Yung L. Y. L.
Published: July 2007

D‐α‐tocopheryl polyethylene glycol succinate (TPGS) has been utilized in numerous drug delivery formulations in recent years. Because of its amphiphilic structure, it can be used as emulsifier and vehicle for lipid‐based drug delivery formulations. It is also an effective P‐glycoprotein (P‐gp) inhibitor. However, TPGS represents only one of the surfactants in the class of “Vitamin‐PEG” conjugated surfactants. To design a new adjuvant or additive, a conjugate made of vitamin D (cholecalciferol) and PEG‐cholecalciferol polyethylene glycol succinate (CPGS) was synthesized via a two‐step reaction. We hypothesized that CPGS may exhibit similar characteristics to TPGS, and thus the physicochemical properties as well as the anticancer properties of CPGS were studied. The results demonstrated that CPGS reduced the particle size and increased the encapsulation efficiency of the PLGA nanoparticles, indicating that CPGS may also have the emulsifier function similar to TPGS. The drug release profiles showed that the nanoparticles with CPGS additive had a lower initial burst and more sustained release pattern. In vitro testing with Caco‐2 cells showed that CPGS could increase the cytotoxicity of DOX‐loaded PLGA nanoparticles. Based on the rhodamine accumulation study, the increased cytotoxicity is possibly due to the P‐gp inhibition by CPGS. From current results, the use of CPGS as an adjuvant is promising and may enhance the efficacy of the overall drug delivery system. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
The response of fibroblasts to hexagonal nanotopography fabricated by electron beam lithography
Authors: Dalby Matthew J. , Gadegaard Nikolaj , Wilkinson Chris D.W.
Published: July 2007

It has been known for many years that cells will react to the shape of their microenvironment. It is more recently becoming clear that cells can alter their morphology, adhesions, and cytoskeleton in response to their nanoenvironment. A few studies have gone further and measured cellular response to high‐adhesion nanomaterials. There have, however, been practical difficulties associated with genomic studies focusing on low‐adhesion nanotopographies. Because of advancement in fabrication techniques allowing the production of large area of structure and the ability to amplify mRNA prior to microarray hybridization, these difficulties can be overcome. Here, electron beam lithography has been used to fabricate arrays of pits with 120 nm diameters, 100 nm depth and 300 nm center to center spacing in hexagonal arrangement. Electron and fluorescent microscopies have been used to observe morphological changes in fibroblasts cultured on the pits. 1.7k gene microarray was used to gauge genomic response to the pits. The results show reduction in cellular adhesion, decrease in spreading, and a broad genomic down‐regulation. Also noted was an increase in endocytotic activity in cells on the pits. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
In situ apatite forming injectable hydrogel
Authors: Ho Emily , Lowman Anthony , Marcolongo Michele
Published: July 2007

Injectable polymers are attractive materials for tissue augmentation or replacement. Thermosensitive hydrogels, especially poly(N‐isopropylacryamide), have been investigated for these applications to exploit the lower critical solution temperature (LCST) which falls between room and body temperatures. Some practical limitations to the material are the load‐bearing capabilities and the ability to bond to the host tissue. In this work, we evaluated a novel, injectable apatite‐forming material system: poly(N‐isopropylacryamide)‐co‐poly(ethyleneglycol) dimethacrylate, with the addition of tri‐methacryloxypropyltrimethoxysilane (MPS). We have previously reported that MPS concentration permits the material system to be tuned to different compressive moduli ranging from 50–700 kPa without altering the LCST of the material. Here, we explore the apatite formation of this material system in protein‐free and protein‐containing SBF. The MPS‐containing hydrogel system exhibited apatite formation throughout the gel thickness. The apatite formation was inhibited by the presence of proteins. This mechanism is likely controlled by the silanol groups (Si‐OH) in MPS, which provided attachment sites for calcium and initiated mineral dissolution from the simulated biological environments. The challenge of this material system is to balance the network‐forming and modulus‐enhancing MPS while maintaining an injectable hydrogel for potential tissue regeneration. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Ginkgolides protect PC12 cells against hypoxia‐induced injury by p42/p44 MAPK pathway‐dependent upregulation of HIF‐1α expression and HIF‐1DNA‐binding activity
Authors: Li Zhu , Ya Ke , Xiao‐Mei Wu , Lei Yang , Yang Lu , Ming Qian Zhong
Published: July 2007

We hypothesized that the neuroprotective role of the standardized Ginkgo biloba (Ginkgoaceae) extract EGb 761 under hypoxic conditions might be associated with its function to increase HIF‐1 activity based on the fact that oxygen availability is crucial for cellular metabolism and viability and that HIF‐1 plays an essential role in cellular oxygen homeostasis under hypoxic conditions. In this study, we therefore investigated the effects of ginkgolides, the main constituent of the non‐flavone fraction of EGb 761, on the content and activity of HIF‐1α, a key factor to determine HIF‐1 activity, in hypoxic PC12 cells induced by cobalt chloride. Our data demonstrated that ginkgolides have a significant protective role against hypoxia‐induced injury in the PC12 cells. The findings also strongly support our hypothesis that the protective role of ginkgolides is due to the up‐regulation of HIF‐1α protein expression and modification through the ginkgolides‐induced activation of the p42/p44 MAPK pathway. In addition, it was evident that ginkgolides could significantly increase the HIF‐1 DNA binding activity, which might also be associated with the protective effects of ginkgolides by promoting the expression of target genes of HIF‐1 under hypoxic conditions. J. Cell. Biochem. 103: 564–575, 2008. © 2007 Wiley‐Liss, Inc.
Proteasomal inhibition and apoptosis regulatory changes in human isolated lymphocytes: The synergistic role of dopamine
Authors: Bazzini Eleonora , Samuele Alberta , Granelli Marcella , Levandis Giovanna , Armentero Marie‐Therese , Nappi Giuseppe , Blandini Fabio
Published: July 2007

Abnormal deposition of protein aggregates and increased susceptibility to apoptotic cell death may result from defects in the activity of the ubiquitin‐proteasome system (UPS); neurotoxicity related to UPS defects seems to require dopamine to be fully expressed. The aim of this study was to investigate the pro‐apoptotic effects caused by proteasomal activity inhibition, as well as the synergistic effect of dopaminergic stimulation in human lymphocytes isolated from healthy volunteers. Cells were incubated 20 h at 37°C, with: (1) lactacystin, (2) increasing concentrations of dopamine or (3) mixture of dopamine and lactacystin. Activities of proteasome 20S and pro‐apoptotic caspases‐3 and ‐9 and levels of anti‐apoptotic Bcl‐2 were measured with fluorimetric or immunochemical assays, while a “DNA diffusion” assay was used to determine the apoptosis. Incubation of lymphocytes with lactacystin, which caused reduction of proteasomal activity, was associated with activation of caspases. A clear, dose‐dependent reduction of proteasomal activity was also seen in the presence of increasing doses of dopamine, which was accompanied by a slight dose‐dependent increase of caspases activities and Bcl‐2 levels. Both effects on proteasome and caspase activities were enhanced when cells were simultaneously exposed to lactacystin and elevated concentrations of dopamine. Apoptosis was detected in all treated samples, but not in controls, without significant differences among the treatment groups; however, the association of dopamine and lactacystin induced a clear reduction in the number of cells being analyzed, pointing to marked cytotoxicity. Our data confirm the potentiation of cytotoxicity related to proteasome inhibition, in the presence of dopaminergic stimulation. J. Cell. Biochem. 103: 877–885, 2008. © 2007 Wiley‐Liss, Inc.
Melanoma cancer vaccines and anti‐tumor T cell responses
Authors: Vujanovic Lazar , Butterfield Lisa H.
Published: July 2007

Melanoma is a disease which has been shown to be responsive to immune intervention. This has been suggested by reports of spontaneous responses of metastatic disease with strong immune infiltrates, and supported by recent data correlating clinical response after IFNα treatment with development of generalized autoimmunity. Since the identification of melanoma‐associated tumor antigens, many groups have performed clinical trials to take advantage of this discovery with melanoma‐specific cancer vaccines. These trials, in which multiple antigen delivery strategies have been tested in hundreds of patients, have demonstrated that these vaccines are safe, immunogenic, and yield a low frequency of objective clinical responses. The ability to perform careful immunological monitoring has allowed important insights into the nature of the anti‐tumor immunity generated by these vaccinations. While many trials have found that the absolute frequency of T cells specific for a vaccine‐encoded antigen are a marker of immunization, it does not correlate with objective clinical response. Induction of broad immunity to multiple tumor antigens, taking advantage of cross‐reactive T cells and activation of persistent T cells may be more important. Harnessing additional modes of amplifying immune responses (lymphodepletion, cytokine support, inhibition of negative immune self‐regulation) are now being tested and should improve clinical responses from 5% to 10% complete response seen currently. J. Cell. Biochem. 102: 301–310, 2007. © 2007 Wiley‐Liss, Inc.
Effects of a phosphinothricin based herbicide on selected groups of soil microorganisms
Authors: Pampulha M. E. , Ferreira M. A. S. S. , Oliveira A.
Published: July 2007

The effects of the herbicide glufosinate‐ammonium on soil microbial populations and activity were observed in a laboratory microcosms over a 40 day period. Culturable aerobic bacteria, fungi and actinomycetes, the fundamental groups of heterotrophic microorganisms, were studied. Nitrifiers, considered a very sensitive group to these compounds were also evaluated. Since herbicides have been found to inhibit decomposition of cellulose in the soil, the effects of glufosinate on cellulolytic bacteria and fungi were determined. Dehydrogenase activity as a measure of microbial activity was another parameter considered. Both stimulating and inhibitory effects on microbial populations were observed, depending on concentration of the herbicide and the period of incubation. A severe inhibiting effect of glufosinate on dehydrogenase activity was found. We concluded that the widespread use of this herbicide may have possible injurious effects on soil microorganisms and their activities. The toxicity exerted by glufosinate may lead to a shift in microbial community structure tending toward a significant loss in functional diversity. Dehydrogenase activity was shown to be an important indicator of glufosinate side‐effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microbial competition, lack in macronutrients, and acidity as main obstacles to the transfer of basidiomycetous ground fungi into (organically or heavy‐metal contaminated) soils
Authors: Gramss Gerhard , Bergmann Hans
Published: July 2007

Non‐symbiotic soil microorganisms which have been expensively engineered or selected to support plant nutrition, control root diseases, degrade xenobiotic hydrocarbons, and repress or stimulate heavy metal uptake of plants fail to survive in target soils. This prompted studies into the role of chemistry and microbial pre‐colonization of 23 top soils in long‐term growth of basidiomycetes. Fungi are seen as auxiliary agents in soil remediation. Untreated soils (1.5 L) were colonized by lignocellulose preferring ground fungi such as Agaricus aestivalis, A. bisporus, A. campestris, A. edulis, A. macrocarpus, A. porphyrizon, Agrocybe dura, A. praecox, Clitocybe sp., Coprinus comatus, Lepista nuda, L. sordida, Macrolepiota excoriata, M. procera, Stropharia coronilla, and S. rugoso‐annulata. Spawn mycelia of fairy‐ring‐type fungi such as Agaricus arvensis, A. fissuratus, A. langei, A. lanipes, A. pilatianus, Lyophyllum sp., and Marasmius oreades died back in contact with non‐sterile soils. Fungal growth correlated positively with the soils' Ct Ca K Mg content and negatively with microbial CO2 evolution. Pasteurization and autoclaving increased mycelial growth and life span in soils pH 6.6–8.2. Growth of pH‐sensitive but not of pH–tolerant fungi was inhibited on the Ca‐deficient soils pH 4–4.4 (–5.6) and was not improved by autoclaving. The pretended fungistasis of acid soils to pH‐sensitive fungi was controlled by N P K mineral (pH not altering) or organic (pH increasing) fertilizing as well as by neutralization with NaOH or CaCO3. Although microbial competition was mortal to 33% of the fungal mycelia inserted into natural unplanted soils, further seriously antifungal effects beyond those pretended by low pH conditions and shortage in mineral macronutrients were not identified. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Responses in the mycelial growth of Aspergillus niger isolates to arsenic contaminated environments and their resistance to exogenic metal stress
Authors: Bučková Mária , Godočíková Jana , Polek Bystrík
Published: July 2007

Isolates of Aspergillus niger, selected from coal dust sediment of a mine containing As (400 mg/kg), pH 3.3–2.8, and from river sediment found near the mine (As, 363 mg/kg, Sb, 93 mg/kg), pH 5.2–4.8, growing on Czapek‐Dox agar exhibited distinct responses in the mycelial growth in arsenic contaminated environments. The radial growth of the isolate from the coal dust in comparison to the control strain from an environment without pollution was reduced approximately to one‐half. It formed black, very small compact colonies, with dense sporulation. The opposite, the strain from the river sediment, grew better in Czapek‐Dox agar like the control. It formed larger colonies with dense centre and strong sporulation. Also, the culture from river sediment developed faster than the coal dust isolate and control strain. Differences were also recorded in size and thickness of conidia heads, phialide, metulae, and conidiophores. Both isolates from contaminated localities exhibited higher tolerance to exogenic toxic effects of As5+, Cd2+ and Cu2+ (5, 25 or 50 mg/l) than the control culture. Tolerance was monitored using the growth of biomass in liquid Czapek‐Dox medium. We confirmed the morphological identification of our isolates to A. niger species with the PCR method. The results refer to complicated relations between biotic and abiotic effects that may directly affect the processes observed in the in situ environment. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antifungal activity of salaceyin A against Colletotrichum orbiculare and Phytophthora capsici
Authors: Park C. N. , Lee D. , Kim W. , Hong Y. , Ahn J. S. , Kim B. S.
Published: July 2007

The antifungal activities of novel salicylic acid derivatives, salaceyin A, 6‐(9‐methyldecyl) salicylic acid, and salaceyin B, 6‐(9‐methylundecyl) salicylic acid were evaluated against plant pathogenic fungi. Salaceyin A showed antifungal activity against Cladosporium cucumerinum, Colletotrichum orbiculare and Phytophthora capsici at 64 μg ml–1 while salaceyin B was less effective. In vitro antifungal activities of the compounds were influenced by the experimental pH value of the MIC test medium wherein their antifungal activities were enhanced by increasingly acidic conditions. Salaceyin A showed potent in vivo control efficacy against Phytophthora blight in pepper plants. The disease was effectively suppressed at 500 μg ml–1, which was comparable to the commercial fungicide, metalaxyl. Salaceyin A suppressed anthracnose development on cucumber leaves in a concentration dependent manner. The control efficacy of salaceyin A against C. orbiculare infection was similar to chlorothalonil when applied prior to pathogen inoculation. Since the salaceyins are derivatives of salicylic acid, a known important signal molecule critical to plant defenses against pathogen invasion, we investigated the possibility that exogenous application of the salaceyin A would activate a systemic acquired resistance against P. capsici infection and C. orbiculare development on pepper and cucumber plants respectively. The addition of 500 μg ml–1 of salaceyin A to the plant root systems did not significantly decrease disease development in the hosts. We are led to conclude that the disease control efficacy of salaceyin A against the Phytophthora blight and anthracnose diseases, mainly originates from the direct interaction of the agent with the pathogens. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)