bluuebunny/crossref_metadata_2025 huggingface dataset:
Serinolic Amino‐s‐triazines: Iterative Synthesis of N‐Substituted Amino‐1,3‐dioxane Derivatives from l‐(p‐Nitrophenyl)serinols and Rotational Stereochemistry Phenomena
Authors: Fazekas Marijana , Pintea Monica , Lameiras Pedro , Lesur Amandine , Berghian Camelia , Silaghi‐Dumitrescu Ioan , Plé Nelly , Darabantu Mircea
Published: April 2008

We report the first iterative and chemioselective approach towards the synthesis of highly elaborated N‐substituted 2,4,6‐triamino‐s‐triazines (melamines) and precursors, by amination of cyanuric chloride with anancomeric and enantiomerically pure primary and tertiary amino‐1,3‐dioxanes. The starting nucleophiles were prepared by direct diastereospecific and diastereoselective acetalization of N‐substituted (1S,2S)‐2‐amino‐1‐(p‐nitrophenyl)propane‐1,3‐diols [l‐(p‐nitrophenyl)serinols]. The stereochemistry of the title compounds is discussed in terms of (pro)diastereomerism originating from restricted rotation about the newly created C(s‐triazine)–N< bonds and supported by NMR and DFT calculation data.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Enantio‐ and Diastereotopos Differentiation in the Palladium(II)‐Catalyzed Hydrosilylation of Bicyclo[2.2.1]alkene Scaffolds with Silicon‐Stereogenic Silanes
Authors: Rendler Sebastian , Fröhlich Roland , Keller Manfred , Oestreich Martin
Published: April 2008

The palladium(II)‐catalyzed hydrosilylation of meso‐configured bicyclo[2.2.1]alkene scaffolds proved to be an invaluable model reaction for the development of reagent‐controlled asymmetric transformations based on silicon‐stereogenic silanes as stereoinducers. In the present investigation, the subtle structural requirements of the silane substitution pattern in enantiotopos‐differentiating single hydrosilylations of a norbornene‐type substrate are disclosed. Extension of this chemistry to a double hydrosilylation of norbornadiene entails a significant increase in stereochemical complexity. Although differentiation of enantiotopic positions by the chiral reagent is demanded in the first hydrosilylation, the same reagent must then differentiate diastereotopic positions in the second. Remarkably high stereocontrol was found in this double hydrosilylation with several silanes first used in the hydrosilylations of the norbornene‐type system. Depending on the enantiomeric purity of the silane, C2‐ and Cs‐symmetric adducts, respectively, were obtained. The identity of the key quaternary silanes was revealed by crystallographic analysis. By this method, the relative and absolute configurations were also assigned, which, in turn, imply that all enantiospecific substitutions at silicon proceed with stereoretention. On the basis of these solid‐state structures, we also discuss the structural implications of silane substitution for the diastereoselectivity‐determining step of this palladium(II)‐catalyzed hydrosilylation reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Regioselective and Stereospecific Halosilylating Cleavage of the Oxirane System of Glycidol Derivatives as an Efficient Strategy to C2‐O‐Functionalized C3‐Vicinal Halohydrins
Authors: Stamatov Stephan D. , Stawinski Jacek
Published: April 2008

Glycidyl esters and ethers undergo a regioselective andstereospecific opening of the oxirane ring upon treatment with trimethylsilyl halides (TMSX, X = Cl, Br, or I) in the presence of pyridine to produce the corresponding C2‐O‐trimethylsilyl‐3(1)‐halo‐sn‐glycerols in high yields. Trifluoroacetylation across the trimethylsilyloxy system of such C3‐synthons with trifluoroacetic anhydride (TFAA) in the presence of a halide anion (e.g. Bu4NX; X = Cl, Br, or I), followed by removal of the trifluoroacetyl transient protection, provides nearly quantitative access to the respective vicinal haloalkanols. Alternatively, C2‐O‐acylated vicinal halohydrins can be obtained in a highly chemo‐/regiospecific manner by direct conversion of the trimethylsilyl protecting group into short‐ or long‐chain ester functionalities by means of a three‐component reagent: pyridine–carboxylic acid–TFAA. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Macrocyclic 14‐Membered Ring Diketal Diamines: Synthesis, Conformational Analysis and 99mTc Radiolabeling Evaluation (Eur. J. Org. Chem. 12/2008)
Authors: Affani Radouane , Auzeloux Philippe , Madelmont Jean‐Claude , Dugat Denise
Published: April 2008

The cover picture shows a rapid approach to new macrocyclic, 14‐membered ring diketal diamines, obtained by reduction of the corresponding diketal dilactams previously synthesized in two steps from chiral or achiral β‐amino alcohols. For these diamino compounds, the conformers of lower energy are either set in a strain‐free rectangular [3434]‐type structure or stabilized by two intramolecular NH···O hydrogen bonds, depending on the nature of the R1, R2 substituents and on the stereochemistry of the OMe groups. Details are discussed in the article by D. Dugat et al. on p. 2039 ff. Lionel Nauton is acknowledged for his help in the design of the cover picture.
A novel approach for analysis of oligonucleotide–cisplatin interactions by continuous elution gel electrophoresis coupled to isotope dilution inductively coupled plasma mass spectrometry and matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Brüchert Wolfram , Krüger Ralf , Tholey Andreas , Montes‐Bayón María , Bettmer Jörg
Published: April 2008

In this work we present a novel approach for in vitro studies of cisplatin interactions with 8‐mer oligonucleotides. The approach is based on the recently developed coupling of continuous elution gel electrophoresis (GE) to an inductively coupled plasma‐sector field mass spectrometer (ICP‐SFMS) with the aim of monitoring the interaction process between this cytostatic drug and the nucleotides. In contrast to existing methods, the electrophoretic separation conditions used here allow both the determination of the reaction kinetics in more detail as well as the observation of dominant intermediates. Two different nucleotides sequences have been investigated for comparison purposes, one containing two adjacent guanines (5′‐TCCGGTCC‐3′) and one with a combination of thymine and guanine (5′‐TCCTGTCC‐3′), respectively. In order to gain further structural information, MALDI‐TOF MS measurements have been performed after fraction collection. This allows for identification of the intermediates and the final products and confirms the stepwise coordination of cisplatin via monoadduct to bisadduct formation. Furthermore, the ICP‐MS results were quantitatively evaluated in order to calculate the kinetics of the entire process.
Recent advances in surface‐enhanced Raman scattering detection technology for microfluidic chips
Authors: Chen Lingxin , Choo Jaebum
Published: April 2008

Microfluidic chip devices and their application to sensitive chemical and biological analyses have attracted significant attention over the past decade. The miniaturization of reaction systems offers practical advantages over conventional benchtop systems. In this case, however, a highly sensitive on‐chip detection method is important for the monitoring of chemical reactions as well as for the detection of analytes inside the channel because the detection volume in a micrometer‐size channel is extremely small. Recently, a surface‐enhanced Raman scattering (SERS) technique is being regarded as a potential candidate for the highly sensitive detection of analytes in a microfluidic chip. This review provides a general survey and an in‐depth look at recent developments in SERS techniques for the biological/environmental analysis of minute analytes in a microfluidic chip.
Chemical cytometry on microfluidic chips
Authors: Yan Hui , Zhang Boyang , Wu Hongkai
Published: April 2008

Chemical cytometry, referring to the analysis of the chemical contents in individual cells, has been in intensive study since Kennedy's first work that was published in Science. The early researches relied on fine‐tip capillaries to capture the cells and do the analyses, which were lab‐ and time‐intensive and required high skills of operation. The emergence of microfluidics has greatly spurred this research field and a great number of research papers have been published in the last decades. Highly integrated microfluidic chips have been developed to capture multiple single cells, lyse them, perform chemical reactions in enclosed microchambers, separate contents by CE and detect chemical species in individual cells. This review focuses on the development of relevant components and their integration for on‐chip chemical cytometry.
Cationized hydroxyethylcellulose as a novel, adsorbed coating for basic protein separation by capillary electrophoresis
Authors: Yang Runmiao , Shi Ronghua , Peng Shuhua , Zhou Dan , Liu Hang , Wang Yanmei
Published: April 2008

We present cationized hydroxyethylcellulose (cat‐HEC) synthesized in our laboratory as a novel physically adsorbed coating for CE. This capillary coating is simple and easy to obtain as it only requires flushing the capillary with polymer aqueous solution. A comparative study with and without polymers was performed. The adsorbed cat‐HEC coating exhibited minimal interactions with basic proteins, providing efficient basic protein separations with excellent reproducibility. Under broad pHs, the amine groups are the main charged groups bringing about a global positive charge on the capillary wall. As a consequence, the cat‐HEC coating produced an anodal EOF performance. A comparative study on the use of hydroxyethylcellulose (HEC) and cat‐HEC as physically adsorbed coatings for CE are also presented. The separation efficiency and analysis reproducibility proved that the cat‐HEC polymer was efficient in suppressing the adsorption of basic proteins onto the silica capillary wall. The long‐term stability of the cat‐HEC coating in consecutive protein separation runs has demonstrated the suitability of the coating for high‐throughput electrophoretic protein separations.
Improving sensitivity by large‐volume sample stacking combined with sweeping without polarity switching by capillary electrophoresis coupled to photodiode array ultraviolet detection
Authors: Zhang Huige , Zhou Lei , Chen Xingguo
Published: April 2008

An easy, simple, and highly efficient on‐line preconcentration method for polyphenolic compounds in CE was developed. It combined two on‐line concentration techniques, large‐volume sample stacking (LVSS) and sweeping. The analytes preconcentration technique was carried out by pressure injection of large‐volume sample followed by the EOF as a pump pushing the bulk of low‐conductivity sample matrix out of the outlet of the capillary without the electrode polarity switching technique using five polyphenols as the model analytes. Identification and quantification of the analytes were performed by photodiode array UV (PDA) detection. The optimal BGE used for separation and preconcentration was a solution composed of 10 mM borate–90 mM sodium cholate (SC)–40% v/v ethylene glycol, without pH adjustment, the applied voltage was 27.5 kV. Under optimal preconcentration conditions (sample injection 99 s at 0.5 psi), the enhancement in the detection sensitivities of the peak height and peak area of the analytes using the on‐line concentration technique was in the range of 18–26‐ and 23–44‐fold comparing with the conventional injection mode (3 s). The detection limits for (−)‐epigallocatechin (EGC), (−)‐epicatechin (EC), (+)‐catechin (C), (−)‐epigallocatechin gallate (EGCG), and (−)‐epicatechin gallate (ECG) were 4.3, 2.4, 2.2, 2.0, and 1.6 ng/mL, respectively. The five analytes were baseline‐separated under the optimum conditions and the experimental results showed that preconcentration was well achieved.
“Electrokinetic Analyte Transport Assay” for α‐fetoprotein immunoassay integrates mixing, reaction and separation on‐chip
Authors: Kawabata Tomohisa , Wada Henry G. , Watanabe Mitsuo , Satomura Shinji
Published: April 2008

A rapid and highly sensitive CE immunoassay method integrating mixing, reaction, separation, and detection on‐chip is described for the measurement of α‐fetoprotein (AFP), a liver cancer marker in blood. Antibody‐binding reagents, consisting of 245‐bp DNA coupled anti‐AFP WA1 antibody (DNA‐WA1) and HiLyte dye‐labeled anti‐AFP WA2 antibody (HiLyte‐WA2), and AFP‐containing sample were filled into adjacent zones of a chip channel defined by the laminar flow lines of the microfluidic device using pressure‐driven flow. The channel geometry was thus used to quantitatively aliquot the reagents and sample into the chip. DNA‐WA1 was electrokinetically concentrated in the channel and sequentially transported through the AFP‐sample zone and HiLyte‐WA2 zone by ITP in such a manner that the AFP sandwich immune complex formation took place in the sample and HiLyte‐WA2 zones. The sandwich AFP immune complex was then detected by LIF after CGE in a separation channel that was arranged downstream of the reaction channel. AFP was detected within 136 s with a detection sensitivity of 5 pM. The on‐chip immunoassay described here, applying ITP concentration, in‐channel reaction, and CGE separation, has the potential of providing a rapid and sensitive method for both clinical and research applications.
On combined ring convolutional coded quantisation and CPM for joint source/channel coding
Authors: Lin Zihuai , Aulin Tor
Published: April 2008

A new trellis‐based coded quantisation scheme using ring convolutional codes is presented. When it is combined with trellis‐coded continuous phase modulation (TCCPM) with convolutional codes over rings, a powerful joint source and channel coding (JSCC) scheme can be formed. We investigate the additive white Gaussian noise (AWGN) channel and the Rayleigh fading channel. Optimal soft decoding for the proposed JSCC scheme is studied. The soft decoder is based on the a posteriori probability (APP) algorithm for TCCPM with ring convolutional codes. It is shown that these systems with soft decoding outperform the same systems with hard decoding especially when the systems operate at low to medium signal‐to‐noise ratio (SNR). It is demonstrated that the new trellis quantisation schemes based on ring convolutional codes is superior to conventional trellis‐coded quantisation (TCQ) of the same complexity. The novelty of this work is in the development of a trellis‐based quantisation method using ring convolutional codes and the use of a soft decoder and the APP algorithm for the combined systems. Copyright © 2008 John Wiley & Sons, Ltd.
A multicommodity model of futures prices: Using futures prices of one commodity to estimate the stochastic process of another
Authors: Cortazar Gonzalo , Milla Carlos , Severino Felipe
Published: April 2008

This article proposes a multicommodity model of futures prices of more than one commodity that allows the use of long‐maturity futures prices available for one commodity to estimate futures prices for the other. The model considers that commodity prices have common and commodity‐specific factors. A procedure for choosing the number of both types of unobservable‐Gaussian factors is presented. Also, it is shown how commodities with and without seasonality may be jointly modeled and how to estimate the model using Kalman filter. Results for the West Texas Intermediate–Brent and for the West Texas Intermediate–unleaded gasoline models presented show strong improvements over the traditional individual‐commodity models, with much lower out‐of‐sample errors and better volatility estimates, even when using fewer factors. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:537–560, 2008
Identification of genomic changes associated with cisplatin resistance in testicular germ cell tumor cell lines
Authors: Noel Elodie E. , Perry Jackie , Chaplin Tracy , Mao Xueying , Cazier Jean‐Baptiste , Joel Simon P. , Oliver R. Tim D. , Young Bryan D. , Lu Yong‐Jie
Published: April 2008

Since the introduction of cisplatin into the clinic, the treatment of patients with a variety of solid tumors including testicular germ cell tumors, ovarian and lung cancers, has dramatically improved. One of the main causes for therapeutic failure in these malignancies is the development of drug resistance. Testicular germ cell tumors (TGCTs), the most common malignancy in young men, exhibit extreme sensitivity to cisplatin‐based chemotherapy, making them an ideal model for investigating the mechanisms of cisplatin chemo‐sensitivity and resistance. TGCT development and pathogenesis have been well studied but little is known about the genetic background in chemo‐resistant cases. We investigated genomic differences between three TGCT parental cell lines and their cisplatin resistant derivatives. Using 10K single nucleotide polymorphism (SNP) microarray analysis, we identified two small chromosomal regions with consistent copy number changes across all three pairs of resistant cell lines. These were an 8.7 Mb region at 6q26‐27, which displayed consistent copy number gain and a 0.3 Mb deletion involving 4 SNPs at 10p14. Both the chromosomal gain and loss were confirmed by fluorescence in situ hybridization. The significance of these regions should be further investigated as they may contain key genes involved in the development of chemo‐ resistance to cisplatin‐based treatment in TGCTs and other cancers. © 2008 Wiley‐Liss, Inc.
Concomitant activation of Wnt pathway and loss of mismatch repair function in human melanoma
Authors: Castiglia Daniele , Bernardini Silvia , Alvino Ester , Pagani Elena , De Luca Naomi , Falcinelli Sabrina , Pacchiarotti Alberto , Bonmassar Enzo , Zambruno Giovanna , D'Atri Stefania
Published: April 2008

Constitutive activation of the Wnt pathway plays a key role in the development of colorectal cancer and has also been implicated in the pathogenesis of other malignancies. Deregulation of Wnt signaling mainly occurs through genetic alterations of APC, the β‐catenin gene (CTNNB1), AXIN1 and AXIN2, leading to stabilization of β‐catenin. Physiologically, AXIN2 is transcriptionally induced on Wnt signaling activation and acts as a negative feedback regulator of the pathway. In colorectal cancer, mutations in CTNNB1 and AXIN2 occur preferentially in tumors with inactivation of the mismatch repair (MMR) genes MSH2, MLH1, or PMS2. In this study, the expression of β‐catenin and AXIN2, and the mutational status of CTNNB1, APC, and AXIN2 were evaluated in two MMR‐deficient (PR‐Mel and MR‐Mel) and seven MMR‐proficient human melanoma cell lines. Only PR‐Mel and MR‐Mel cells showed nuclear accumulation of β‐catenin and expression of the AXIN2 gene, and hence, constitutive activation of Wnt signaling. Mutational analysis identified a somatic heterozygous missense mutation in CTNNB1 exon three and a germline heterozygous deletion within AXIN2 exon seven in PR‐Mel cells, and a somatic biallelic deletion within APC in MR‐Mel cells. Deregulation of Wnt signaling and a defective MMR system were also present in the original tumor of PR and MR patients. Thus, we describe additional melanomas with mutations in CTNNB1 and APC, identify for the first time a germline AXIN2 mutation in a melanoma patient and suggest that inactivation of the MMR system and deregulation of the Wnt/β‐catenin signaling pathway cooperate to promote melanoma development and/or progression. © 2008 Wiley‐Liss, Inc.
Predicting river width, depth and velocity at ungauged sites in England and Wales using multilevel models
Authors: Booker D. J. , Dunbar M. J.
Published: April 2008

Using a dataset of gauged river discharges taken from sites in England and Wales, linear multilevel models (also known as mixed effects models) were applied to quantify the variability in discharge and the discharge‐hydraulic geometry relationships across three nested spatial scales. A jackknifing procedure was used to test the ability of the multilevel models to predict hydraulic geometry, and therefore width, mean depth and mean velocity, at ungauged stations. These models provide a framework for making predictions of hydraulic geometry parameters, with associated levels of uncertainty, using different levels of data availability. Results indicate that as one travels downstream along a river there is greater variability in hydraulic geometry than is the case between rivers of similar sizes. This indicates that hydraulic geometry (and therefore hydrology) is driven by catchment area, to a greater extent than by natural geomorphological variations in the streamwise direction at the mesoscale, but these geomorphological variations can still have a major impact on channel structure. Copyright © 2008 John Wiley & Sons, Ltd.
Assessment of annual high‐water events for the Mackenzie River basin, Canada
Authors: de Rham Laurent P. , Prowse Terry D. , Beltaos Spyros , Lacroix Martin P.
Published: April 2008

River ice break‐up is known to have important morphological, ecological and socio‐economic effects on cold‐regions river environments. One of the most persistent effects of the spring break‐up period is the occurrence of high‐water events. A return‐period assessment of maximum annual nominal water depths occurring during the spring break‐up and open‐water season at 28 Water Survey of Canada hydrometric sites over the 1913–2002 time period in the Mackenzie River basin is presented. For the return periods assessed, 13 (14) stations are dominated by peak events occurring during the spring break‐up (open‐water) season. One location is determined to have a mixed signal. A regime classification is proposed to separate ice‐ and open‐water dominated systems. As part of the regime classification procedure, specific characteristics of return‐period patterns including alignment, and difference between the 2 and 10‐year events are used to identify regime types. A dimensionless stage‐discharge plot allows for a contrast of the relative magnitudes of flows required to generate maximum nominal water‐depth events in the different regimes. At sites where discharge during the spring break‐up is approximately one‐quarter or greater than the magnitude of the peak annual discharge, nominal water depths can be expected to exceed those occurring during the peak annual discharge event. Several physical factors (location, basin area, stream order, gradient, river orientation, and climate) are considered to explain the differing regimes and discussed relative to the major sub‐regions of the MRB. Copyright © 2008 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.
Regulation of adult human mesenchymal stem cells into osteogenic and chondrogenic lineages by different bioreactor systems
Authors: Wang Tzu‐Wei , Wu Hsi‐Chin , Wang Hsin‐Yen , Lin Feng‐Huei , Sun Jui‐Sheng
Published: April 2008

The aim of this study was to examine the feasibility of expanding and regulating mesenchymal stem cells (MSCs) from isolated adult human bone marrow mononuclear cells, seeded on gelatin–hyaluronic acid biomatrices, and then to quantitatively compare the gene expression in three different culture systems. Individual and interactive effects of model system parameters on construct structure, function, and molecular properties were evaluated. The results showed that these adult human MSCs even at old age not only expressed primitive mesenchymal cell markers but also maintained a high level of colony‐forming efficiency and were capable of differentiating into osteoblasts, chondrocytes, and adipocytes upon appropriate inductions. After 21 days of culture, we found that the osteoblastic and chondrocytic lineage gene expression were earlier and higher expressed in spinner flask bioreactor culture group when compared with the static culture and rotating wall vessel reactor culture. The osteogenic lineage proteins type I collagen, alkaline phosphatase, and osteocalcin were strongly stained in histological sections of spinner flask bioreactor culture, whereas these were less detected in the other two groups, especially in rotating wall vessel reactor culture. As for the markers associated with the chondrogenic lineage differentiation proteins, type II collagen was apparently expressed in spinner flask culture group, while the expression of proteoglycans (aggreacan, decorin) in three culture conditions took the lead of each other. We conclude that the spinner flask bioreactor with appropriate induction medium reported in this study may be used to rapidly expand adult MSCs and is likely to possess better induction results toward osteoblastic and chondrocytic lineages. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Photoreversibility and photostability in films of octopus rhodopsin isolated from octopus photoreceptor membranes
Authors: Paternolli Cristina , Neebe Martin , Stura Enrico , Barbieri Francesca , Ghisellini Paola , Hampp Norbert , Nicolini Claudio
Published: April 2008

In this work, a new biomaterial resulting from the isolation of octopus rhodopsin (OR) starting from octopus photoreceptor membranes is presented. Mass spectroscopic characterization was employed in order to verify the presence of rhodopsin in the extract. Photoreversibility and photochromic properties were investigated using spectrophotometric measurements and pulsed light. Thin films of OR were realized using the gel‐matrix entrapment method in polyvinyl alcohol solution. The results indicate that the photoreversibility and the photostability of the OR in gel‐matrices are maintained. Several measurements were performed to test the stability of the resulting biomaterial in time and at room temperature. Preliminary tests demonstrate that the photoreversibility and the photostability are still found after few days from the biomaterial preparation and after the exposure for several hours at room temperature. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Biodegradable fumarate‐based drug‐delivery systems for ophthalmic applications
Authors: Hacker M. C. , Haesslein A. , Ueda H. , Foster W. J. , Garcia C. A. , Ammon D. M. , Borazjani R. N. , Kunzler J. F. , Salamone J. C. , Mikos A. G.
Published: April 2008

The function of a photocrosslinked poly(propylene fumarate) (PPF)/poly(N‐vinyl pyrrolidone) (PVP) matrix for the sustained release of three ophthalmic model drugs, acetazolamide (AZ), dichlorphenamide (DP), and timolol maleate (TM), was investigated. The drugs differ in molecular weight and degree of dissociation in aqueous environments; both are parameters that significantly influence drug diffusivity. AZ, DP, and TM‐loaded cylindrical rods (10 mm length, 0.6 mm diameter) were fabricated by photoinduced cross‐copolymerization of PPF and N‐vinyl pyrrolidone (NVP) in molds. The released amounts of AZ, DP, TM, and NVP were determined by high‐performance liquid chromatography (HPLC). The effects of drug properties and loading on the release kinetics were investigated. The in vitro release of AZ, DP, and TM was well sustained from the polymer matrices over a period of ∼210, 270, and 250 days, respectively. The release kinetics correlated with the HPLC retention profiles of the different drugs. Following a small initial burst release (<10%), a dual modality release controlled by diffusion and bulk erosion was found for all drugs. Drug release rates of up to 4 μg/day were reached. Matrix drug loading generally affected the extent of the burst release, release kinetics, as well as the matrix water content and matrix degradation that were determined gravimetrically. Microcomputed tomography was used to image structural and dimensional changes of the devices. A preliminary rabbit implantation study revealed promising ocular biocompatibility of drug‐free PPF/PVP matrices. All results indicate the potential of photocrosslinked PPF‐based matrices as polymeric carriers for long‐term ophthalmic drug delivery. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Rheological, microstructural, and in vitro characterization of hybrid chitosan‐polylactic acid/hydroxyapatite composites
Authors: Araújo A. B. A. , Lemos A. F. , Ferreira J. M. F.
Published: April 2008

In this work, hybrid chitosan/hydroxyapatite composites material were developed and characterized. The polymer matrix was first dissolved in polylactic acid, and then hydroxyapatite (HA) was added as filler material. The effects of the added amounts of a crosslinking agent (genipin) and of the concentrations of lactic acid, and of the presence of HA powder on the evolution of rheological properties were evaluated. A significant decrease of gelation time with increasing amounts of crosslinking agent was observed, the effect being even more pronounced in the presence of HA. The chitosan matrix and the composites with a chitosan/HA weight ratio of 2/5 were characterized using microstructural analysis and in vitro tests. The formation of large pore sizes in the chitosan‐based scaffolds was favored by low concentrations of lactic acid and genipin. The in vitro tests in synthetic body fluid revealed an extensive formation of an apatitic layer onto the surface of the chitosan/HA composite scaffolds crosslinked with genipin. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Preparation and cytocompatibility of PLGA scaffolds with controllable fiber morphology and diameter using electrospinning method
Authors: Zhao Li , He Chenguang , Gao Yongjuan , Cen Lian , Cui Lei , Cao Yilin
Published: April 2008

Poly(lactide‐co‐glycolide) (PLGA) scaffolds prepared by the electrospinning technology were paid more attention in tissue engineering, but detailed investigation on the influence of process parameters on scaffold morphology and fiber diameters as well as distribution remains to be conducted. In the current study, PLGA concentration, electric field strength, and feeding rate were varied to prepare different PLGA scaffolds. It was shown that with the varying of the above parameters, the electrospun porous PLGA scaffolds exhibited fibrous morphology either with/out beads or bead‐fiber string. The diameter of nanofibers increased with the PLGA concentration and feeding rate, whereas the electric field strength exerted only minor effects on the average diameter of the nanofibers. The cytocompatibility of the scaffold prepared from optimizing fabrication parameters was evaluated using human fibroblasts. Good cell attachment, fast proliferation rate, characteristic fibroblast morphology with homogeneous distribution was observed on the scaffold. As a whole, this study demonstrated that the fiber morphology and diameter of the electrospun PLGA scaffolds could be tailored by controlling fabrication parameters. And nanofibrous PLGA could act as a biologically preferred scaffold for fibroblasts growth with maintenance of characteristic morphology. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Spatiotemporal dynamics of regulatory protein recruitment at DNA damage sites
Authors: Mortusewicz Oliver , Leonhardt Heinrich , Cardoso M. Cristina
Published: April 2008

Mammalian cells are constantly threatened by multiple types of DNA lesions arising from various sources like irradiation, environmental agents, replication errors or by‐products of the normal cellular metabolism. If not readily detected and repaired these lesions can lead to cell death or to the transformation of cells giving rise to life‐threatening diseases like cancer. Multiple specialized repair pathways have evolved to preserve the genetic integrity of a cell. The increasing number of DNA damage sensors, checkpoint regulators, and repair factors identified in the numerous interconnected repair pathways raises the question of how DNA repair is coordinated. In the last decade, various methods have been developed that allow the induction of DNA lesions and subsequent real‐time analysis of repair factor assembly at DNA repair sites in living cells. This combination of biophysical and molecular cell biology methods has yielded interesting new insights into the order and kinetics of protein recruitment and identified regulatory sequences and selective loading platforms for the efficient restoration of the genetic and epigenetic integrity of mammalian cells. J. Cell. Biochem. 104: 1562–1569, 2008. © 2008 Wiley‐Liss, Inc.
2‐methoxyestradiol‐induced cell death in osteosarcoma cells is preceded by cell cycle arrest
Authors: Maran Avudaiappan , Shogren Kristen L. , Benedikt Michaela , Sarkar Gobinda , Turner Russell T. , Yaszemski Michael J.
Published: April 2008

2‐Methoxyestradiol (2‐ME), a naturally occurring mammalian metabolite of 17β‐Estradiol (E2), induces cell death in osteosarcoma cells. To further understand the molecular mechanisms of action, we have investigated cell cycle progression in 2‐ME‐treated human osteosarcoma (MG63, SaOS‐2 and LM8) cells. At 5 µM, 2‐ME induced growth arrest by inducing a block in cell cycle; 2‐ME‐treatment resulted in 2‐fold increases in G1 phase cells and a decrease in S phase cells in MG63 and SaOS‐2 osteosarcoma cell lines, compared to the appropriate vehicle controls. 2‐ME‐treatment induced a threefold increase in the G2 phase in LM8 osteosarcoma cells. The results demonstrated steroid specificity, as the tumorigenic metabolite, 16α‐hydroxyestradiol (16‐OHE), did not have any effect on cell cycle progression in osteosarcoma cells. The cell cycle arrest coincided with an increase in expression of the cell cycle markers p21, p27 and p53 proteins in 2‐ME‐treated osteosarcoma cells. Also, MG63 cells, transiently transfected with cDNA for a ‘loss of function mutant’ RNA‐dependent protein kinase (PKR) protein, were resistant to 2‐ME‐induced cell cycle arrest. These results suggest that 2‐ME works in concert with factors regulating cell cycle progression, and cell cycle arrest precedes cell death in 2‐ME‐treated osteosarcoma cells. J. Cell. Biochem. 104: 1937–1945, 2008. © 2008 Wiley‐Liss, Inc.
Oxidation and nuclear localization of thioredoxin‐1 in sparse cell cultures
Authors: Spielberger Jeanine C. , Moody Amie D. , Watson Walter H.
Published: April 2008

Reactive oxygen species (ROS) were once viewed only as mediators of toxicity, but it is now recognized that they also contribute to redox signaling through oxidation of specific cysteine thiols on regulatory proteins. Cells in sparse cultures have increased ROS relative to confluent cultures, but it is not known whether protein redox states are affected under these conditions. The purpose of the present study was to determine whether culture conditions affect the redox state of thioredoxin‐1 (Trx1), the protein responsible for reducing most oxidized proteins in the cytoplasm and nucleus. The results showed that Trx1 was more oxidized in sparse HeLa cell cultures than in confluent cells. The glutathione pool was also more oxidized, demonstrating that both of the major cellular redox regulating systems were affected by culture density. In addition, the total amount of Trx1 protein was lower and the subcellular distribution of Trx1 was different in sparse cells. Trx1 in sparse cultures was predominantly nuclear whereas it was predominantly cytoplasmic in confluent cultures. This localization pattern was not unique to HeLa cells as it was also observed in A549, Cos‐1 and HEK293 cells. These findings demonstrate that Trx1 is subject to changes in expression, redox state and subcellular localization with changing culture density, indicating that the redox environments of the cytoplasm and the nucleus are distinct and have different requirements under different culture conditions. J. Cell. Biochem. 104: 1879–1889, 2008. © 2008 Wiley‐Liss, Inc.
c‐Jun NH2‐terminal kinase (JNK)‐dependent nuclear translocation of apoptosis‐inducing factor (AIF) following engagement of membrane immunoglobulin on WEHI‐231 B lymphoma cells
Authors: Takada Eiko , Hata Kikumi , Mizuguchi Junichiro
Published: April 2008

WEHI‐231 B lymphoma cells have been employed for analysis of antigen‐induced B cell unresponsiveness because these cells undergo cell cycle arrest in G1, accompanied by induction of apoptosis. In the present study, we examined the requirement for toxic small molecules apoptosis‐inducing factor (AIF) and cytochrome c, and subsequent caspase activation in apoptotic cell death in WEHI‐231 and CH31 B lymphoma cells following engagement of membrane immunoglobulin (mIg). Pan‐caspase inhibitor BD‐fmk blocked mIg‐mediated increase in cells with sub‐G1 DNA content, whereas it did not affect mIg‐mediated loss of mitochondrial membrane potential and phosphatidylserine exposure on B cell membrane. Dominant‐negative form of c‐Jun NH2‐terminal kinase1 (JNK1) blocked the translocation of AIF into the nuclei and cytosol from the mitochondria in the WEHI‐231 and CH31 cells following mIg engagement, whereas constitutively active form of JNK1 enhanced it. This AIF translocation was also blocked by Bcl‐xL, but not by BD‐fmk. Moreover, AIF‐deficient clones via small interfering RNA (siRNA)‐mediated method showed small increase in loss of mitochondrial membrane potential. After mIg engagement, the AIF‐deficient clones displayed an enhanced sensitivity to mIg‐mediated apoptosis, concomitant with translocation of a residual AIF into the nuclei, compared with control clone. Our findings are compatible with the notion that AIF has dual role, with a proapoptotic function in the nuclei and a distinct anti‐apoptotic function in the mitochondria. These observations would be valuable for analysis of B cell unresponsiveness and hopefully for treatment of diseases involving B cell dysfunction. J. Cell. Biochem. 104: 1927–1936, 2008. © 2008 Wiley‐Liss, Inc.
Competence and scope of practice: ethics and professional development
Authors: Wise Erica H.
Published: April 2008

In this article, I discuss the importance of the psychotherapist's capacities and attributes that go beyond formal education and training as they relate to both readiness for clinical training and continued competence throughout one's professional life. Professional development is essential to the maintenance of professional competence as a psychotherapist. Principles and standards from the American Psychological Association's (2002) Ethics Code are reviewed and illustrated with clinical vignettes. In striving to maintain competence, psychotherapists are strongly encouraged to focus on proactive self‐care and professional development in addition to complying with the formal continuing education mandated by most states. © 2008 Wiley Periodicals, Inc. J Clin Psychol: In Session 64: 1–12, 2008.
The CM cell line derived from liver metastasis of malignant human insulinoma is not a valid beta cell model for in vitro studies
Authors: Gragnoli Claudia
Published: April 2008

The CM cell line is derived from the ascitic fluid of a patient with liver metastasis of a malignant insulinoma. Insulin levels potentially derived from the insulinoma were detected only once in vivo in the subject with the malignant pancreatic tumor and hypoglycemia. After multiple unsuccessful attempts to detect insulin in the culture medium, insulin levels were again detected only once in vitro. In our repeated experiments, we extensively exposed early‐passages of the CM cell line to 0.91 mM glucose and acutely to increasingly higher glucose concentrations (2.75, 5.5, 11, and 22 mM) and did not detect any insulin secretion as well as any significant insulin cell content. The electronic microscopic examinations of several vials containing early‐passages of the CM cell lines showed a polyclonal nature of the cells mostly resembling fibroblasts. The karyotype detected severe and consistent chromosomal aberrations of the CM cell line, including the chromosome 11 tetraploidy and the genetic material translocation in three out of four chromosomes 11 at the insulin gene locus 11p15.1. These data, unfortunately, exclude the possibility of considering the CM cell line as a valid beta cell model in vitro. J. Cell. Physiol. 216: 569–570, 2008. © 2008 Wiley‐Liss, Inc.
Application of supercritical fluid chromatography to the analysis of hydrophobic metabolites
Authors: Bamba Takeshi
Published: April 2008

This review describes the usefulness of supercritical fluid chromatography (SFC) in the analysis of hydrophobic metabolites. The use of SFC for the analysis of naturally occurring polyprenols markedly improves the chromatographic resolution of polyprenol homologues and their geometric isomers as compared to conventional HPLC. Under optimized SFC conditions, individual homologues with 10–100‐mers were separated. Furthermore, we established an analytical system for the fingerprinting and profiling of diverse lipids through the usage of SFC‐MS. When a cyanopropylated silica gel packed column was used for the separation, 14 lipids were successfully detected, and the time required for analysis was less than 15 min. The use of an octadecylsilylated column for the separation depended on the differences in the fatty acid side chains. SFC is a useful separation technology for hydrophobic metabolites, which are difficult to be separated by HPLC.
Supercritical fluid assisted, integrated process for the synthesis and separation of different lipid derivatives
Authors: Weber Andreas , Catchpole Owen , Eltringham Wayne
Published: April 2008

The partial synthesis of ethyl esters from corn and fish oil was carried out in a stirred tank at supercritical conditions and the products were separated from the reaction mixture using the supercritical fluid. Corn oil can be almost completely converted to ethyl esters under optimized conditions and the rate of reaction is comparable to atmospheric pressure conditions. Some concentration of polyunsaturates occurs in the partially converted glyceride fraction of fish oil, as the enzyme used, Lipozyme® TL‐IM, allows preferential esterification of the saturates and mono‐unsaturates that are concentrated in positions 1 and 3 of the triglycerides. By judicious selection of the processing conditions, good separation of ethyl esters from the partially reacted glycerides was achieved.
Inhibitory effects of trans‐resveratrol analogs molecules on the proliferation and the cell cycle progression of human colon tumoral cells
Authors: Marel Anna‐Kristina , Lizard Gérard , Izard Jean‐Claude , Latruffe Norbert , Delmas Dominique
Published: April 2008

Resveratrol may function as a cancer chemopreventive agent. However, few data are available on the antitumoral activities of its dimer, ε‐viniferin, also present in human diet. So, the effects of resveratrol, ε‐viniferin, of their acetylated forms (resveratrol triacetate, ε‐viniferin pentaacetate) and of vineatrol (a wine grape extract) were compared on human adenocarcinoma colon cells. Resveratrol and resveratrol triacetate inhibit cell proliferation and arrest cell cycle. ε‐Viniferin and ε‐viniferin pentaacetate slightly reduce cell proliferation. Vineatrol inhibits cell proliferation and favors an accumulation in the S phase of the cell cycle. Consequently, resveratrol triacetate and vineatrol could constitute new putative anticancer agents on colon carcinoma.
Quantification of the thaumatin‐like kiwi allergen by a monoclonal antibody‐based ELISA
Authors: Gavrović‐Jankulović Marija , Spasić Milena , Ćirković Veličković Tanja , Stojanović Marijana , Inić‐Kanada Aleksandra , Dimitrijević Ljiljana , Lindner Buko , Petersen Arnd , Becker Wolf‐Meinhard , Jankov Ratko M.
Published: April 2008

Thaumatin‐like proteins (TLPs) have been established as a new family of fruit and pollen allergens. The aim of this study was to develop a two‐site ELISA for the quantification of the thaumatin‐like kiwi allergen (Act d 2) in kiwifruit extracts and kiwifruit‐containing food products. Genomic DNA (gDNA) of Act d 2 was amplified and the deduced amino acid sequence was determined to obtain a primary structure. Act d 2 purified from kiwifruit extract by HPLC was identified by Edman degradation and MS. Balb/c mice were immunized with Act d 2 for the production of mAbs by hybridoma technology. The optimized ELISA measured Act d 2 concentrations ranging from 0.2 to 9.0 ng/mL, with intra‐ and interassay coefficients of variation of 3.65 and 10.44%, respectively. The developed ELISA is a useful method for the quantification of the thaumatin‐like kiwi allergen in kiwifruit extracts as well as the allergen level in kiwifruit‐containing food products. It may be a helpful analytical tool for the evaluation of the stability (integrity) of fruit allergen extracts for in vitro diagnosis.
Erythrodiol, a natural triterpenoid from olives, has antiproliferative and apoptotic activity in HT‐29 human adenocarcinoma cells
Authors: Juan M. Emília , Wenzel Uwe , Daniel Hannelore , Planas Joana M.
Published: April 2008

Erythrodiol is the precursor of pentacyclic triterpenic acids present in Olea Europaea. Although olive oil and some of its constituents are reported to have anticarcinogenic activities, erythrodiol has not been assessed in its cell biological functions in detail. We therefore determined its effects on cell growth and apoptosis in human colorectal carcinoma HT‐29 cells. Proliferation, cytotoxicity, and apoptosis were measured by fluorescence‐based techniques. Erythrodiol inhibited cell growth with an EC50 value of 48.8 ± 3.7 μM without any cytotoxic effects in a concentration range up to 100 μM. However, exposure of cells for 24 h to 50, 100, and 150 μM erythrodiol increased caspase‐3‐like activity by 3.2‐, 4.8‐, and 5.2‐fold over that in control cells. We here demonstrate for the first time that, in colon adenocarcinoma cells, erythrodiol exerts antiproliferative and proapoptotic activity.
S100B Protein concentration in milk‐formulas for preterm and term infants Correlation with industrial preparation procedures
Authors: Nigro Francesco , Gagliardi Luigi , Ciotti Sabina , Galvano Fabio , Pietri Amedeo , Tina Gabriella Lucia , Cavallaro Daniela , La Fauci Luca , Iacopino Leonardo , Bognanno Matteo , Li Volti Giovanni , Scacco Antonio , Michetti Fabrizio , Gazzolo Diego
Published: April 2008

Human milk S100B protein possesses important neurotrophic properties. However, in some conditions human milk is substituted by milk formulas. The aims of the present study were: to assess S100B concentrations in milk formulas, to verify any differences in S100B levels between preterm and term infant formulas and to evaluate the impact of industrial preparation at predetermined phases on S100B content. Two different set of samples were tested: (i) commercial preterm (n = 36) and term (n = 36) infant milk formulas; ii) milk preterm (n = 10) and term infant (n = 10) formulas sampled at the following predetermined industrial preparation time points: skimmed cow milk (Time 0); after protein sources supplementation (Time 1); after pasteurization (Time 2); after spray‐drying (Time 3). Our results showed that S100B concentration in preterm formulas were higher than in term ones (p < 0.01). In addition, S100B concentrations during industrial preparation showed a significant increase (p < 0.001) at Time 1 followed by a slight decrease (p > 0.05) at Time 2, whereas a significant (p < 0.001) dip was observed at Time 3. In conclusion, S100B showed a sufficient thermostability to resist pasteurization but not spry‐drying. New feeding strategies in preterm and term infants are therefore warranted in order to preserve S100B protein during industrial preparation.
The influence of selenium on immune responses
Authors: Hoffmann Peter R. , Berry Marla J.
Published: April 2008

Selenium (Se) is a potent nutritional antioxidant that carries out biological effects through its incorporation into selenoproteins. Given the crucial roles that selenoproteins play in regulating reactive oxygen species (ROS) and redox status in nearly all tissues, it is not surprising that dietary Se strongly influences inflammation and immune responses. The notion that Se “boosts” the immune system has been supported by studies involving aging immunity or protection against certain pathogens. However, studies examining the effects of Se status on other types of immunity such as antiparasitic responses or allergic asthma have suggested more Se may not always be beneficial. In this review, we summarize and compare the available data regarding how the levels of Se affect different types of immunity. Overall, determining how Se intake differentially affects various types of immune responses and dissecting the mechanisms by which this occurs will lead to a better utilization of Se‐supplementation for human diseases involving the immune system.