bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semi‐Markov Processes and Hidden Models
Authors: Limnios Nikolaos 
Published: June 2010

Abstract
The purpose of this article is to present the semi‐Markov processes focusing on applications, especially in reliability and dependability. The semi‐Markov processes under consideration are both of continuous and discrete time with countable or finite state space. The basic definitions of Markov renewal and semi‐Markov processes are presented, as well as the Markov renewal theorem and the some theory of statistical estimation. In the sequel, we describe a general reliability model and give the corresponding estimations. Finally, we briefly present the semi‐Markov chain and hidden semi‐Markov models. Some bibliographical directions for further relevant topics, which are not included in this article, are given.
Availability Analysis: Concepts and Methods
Authors: Zio Enrico 
Published: June 2010

Abstract
Availability is a concept used to characterize the performance of a machine, component, or system with respect to its ability to fulfill the function for which it is operated. In this article, a general introduction to quantitative modeling for the availability analysis of components and systems is provided. Both, cases of continuously monitored and periodically tested components are considered. Markov modeling and Monte Carlo simulation are presented as methods for the evaluation of the availability of complex systems.
TG101209, a novel JAK2 inhibitor, has significant in vitro activity in multiple myeloma and displays preferential cytotoxicity for CD45+ myeloma cells
Authors: Ramakrishnan Vijay , Kimlinger Teresa , Haug Jessica , Timm Michael , Wellik Linda , Halling Timothy , Pardanani Animesh , Tefferi Ayalew , Vincent Rajkumar Sundararasan , Kumar Shaji 
Published: June 2010

AbstractInteraction of myeloma cells with the bone marrow microenvironment is mediated in large part through different cytokines, especially VEGF and IL6. These cytokines, especially IL6, leads to upregulation of the JAK/STAT pathway in myeloma cell, contributing to increased proliferation, decreased apoptosis, and acquired drug resistance. Here, we examined the preclinical activity of a novel JAK2 inhibitor TG101209. TG101209 induced dose‐ and time‐dependent cytotoxicity in a variety of multiple myeloma (MM) cell lines. The induction of cytotoxicity was associated with inhibition of cell cycle progression and induction of apoptosis in myeloma cell lines and patient‐derived plasma cells. Evaluation of U266 cell lines and patient cells, which have a mix of CD45 positive and negative cells, demonstrated more profound cytotoxicity and antiproliferative activity of the drug on the CD45+ population relative to the CD45− cells. Exploring the mechanism of action of TG101209 indicated downregulation of pJak2, pStat3, and Bcl‐xl levels with upregulation of pErk and pAkt levels indicating cross talk between signaling pathways. TG101209, when used in combination with the PI3K inhibitor LY294002, demonstrated synergistic cytotoxicity against myeloma cells. Our results provide the rationale for clinical evaluation of TG101209 alone or in combination with PI3K/Akt inhibitors in MM. Am. J. Hematol., 2010. © 2010 Wiley‐Liss, Inc.
A novel initiating system for ring‐opening polymerization of ε‐caprolactone: Synthesis of triarm star‐shaped poly(ε‐caprolactone)
Authors: Zhu Weipu , Tong Xiaowei , Xie Weihui , Shen Zhiquan 
Published: June 2010

AbstractThe rare earth compound, scandium trifluoromethanesulfonate [Sc(OTf)3], has been used as a water‐tolerant catalyst for the synthesis of star‐shaped poly(ε‐caprolactone)s (SPCLs) with trimethylol propane as trifunctional initiator in solvent at 40°C. Triarm SPCLs have been successfully prepared. The molar mass of SPCLs were determined by end‐group 1H NMR analyses, which could be well controlled by the molar ratio of the monomer to the initiator, and were independent of the amount of Sc(OTf)3 used. Differential scanning calorimetry analyses suggested that the maximal melting point, the cold crystallization temperature, and the degree of crystallinities of SPCLs increased with the increasing of the molar mass and were lower than the linear poly(ε‐caprolactone) (LPCL) with similar molar mass. Furthermore, polarized optical microscopy indicated that LPCL showed fast crystallization rate and good spherulitic morphology with apparent Maltese cross pattern, whereas SPCLs exhibit much lower crystallization rate and poor spherulitic morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Bubble growth in the microcellular foaming of CO2/polypropylene solutions
Authors: Zhang Ping , Wang Xiao‐Jun , Yang Yong , Zhou Nan‐Qiao 
Published: June 2010

AbstractThis article is concerned with bubble growth dynamics in the CO2/polypropylene microcellular foaming process. The effect of the melt strength on the bubble growth was thoroughly investigated in theory for the first time. The theoretical results indicate that enhanced melt strength effectively restrains the bubble growth and stabilizes the bubble oscillation. Higher melt strength leads to lower bubble growth rate, shorter growth time, and smaller ultimate bubble size. Compared to the melt strength, the viscoelasticity and the gas pressure have less effect on the microcellular foaming process. The bubble growth varies a little as the viscoelasticity is varied. The bubble oscillation and growth rate are enhanced with increasing gas pressure, which leads to the augmentation of the bubble size. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The comparative study of photocatalytic self‐cleaning properties of synthesized nanoscale titania and zirconia onto polyacrylonitrile fibers
Authors: Moafi Hadi Fallah , Shojaie Abdollah Fallah , Zanjanchi Mohammad Ali 
Published: June 2010

AbstractThe photocatalytic activity of TiO2 and ZrO2‐coated polyacrylonitrile (PAN) fibers was compared through the self‐cleaning of methylene blue and eosin yellowish. TiO2 and ZrO2 nanocrystals were successfully synthesized and deposited onto PAN fibers with photocatalytic self‐cleaning activity using the sol‐gel process at low temperature. The pristine and treated samples have been characterized by several techniques, such as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The TiO2 nanoparticles with 10–20 nm in size, and ZrO2 with 20–40 nm have been synthesized to form dispersed particles on the fiber surface, which shows photocatalytic properties when exposed to UV–Vis light. The photocatalytic activity, tested by measuring the degradation of adsorbed methylene blue and Eosin Y. Photocatalytic activity of TiO2‐coated fibers toward dyes degradation was higher than that of ZrO2‐coated fibers. This preparation technique can be also applied to new fabrics to create self‐cleaning and UV irradiation protection properties in them. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Controlled size chitosan nanoparticles as an efficient, biocompatible oligonucleotides delivery system
Authors: Manchanda Romila , Nimesh Surendra 
Published: June 2010

AbstractPolymeric nanoparticles of chitosan crosslinked with glutaraldehyde have been prepared using reverse micellar system. An optically clear solution was obtained on redispersing these nanoparticles in aqueous buffer. The nanoparticles were characterized for their size and surface morphology employing dynamic laser scattering (DLS) and transmission electron microscopy (TEM). The TEM images showed spherical particles with smooth surface and narrow size distribution of about 90 nm, which was also supported by DLS data. Size and morphology of the particles remains the same on redispersing the lyophilized powder of these nanoparticles in aqueous buffer. Further, these nanoparticles were loaded with different synthetic oligonucleotides (ODNs). In vitro pH dependent release of the adsorbed oligonucleotides from these nanoparticles was also studied. At basic pH the release of oligonucleotides was found higher as compared with neutral and acidic medium. Cytotoxicity studies done on HEK 293 cells reveals that oligonucleotide loaded nanoparticles have high cell viability of nearly 76–88% whereas those of lipofectamine was about 35%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Use of Side‐Chain Incompatibility for Tailoring Long‐Range p/n Heterojunctions: Photoconductive Nanofibers Formed by Self‐Assembly of an Amphiphilic Donor–Acceptor Dyad Consisting of Oligothiophene and Perylenediimide
Authors: Li Wei‐Shi , Saeki Akinori , Yamamoto Yohei , Fukushima Takanori , Seki Shu , Ishii Noriyuki , Kato Kenichi , Takata Masaki , Aida Takuzo 
Published: June 2010

AbstractTo tailor organic p/n heterojunctions with molecular‐level precision, a rational design strategy using side‐chain incompatibility of a covalently connected donor–acceptor (D–A) dyad has been successfully carried out. An oligothiophene–perylenediimide dyad, when modified with triethylene glycol side chains at one terminus and dodecyl side chains at the other (2 Amphi), self‐assembles into nanofibers with a long‐range D/A heterojunction. In contrast, when the dyad is modified with dodecyl side chains at both termini (2 Lipo), ill‐defined microfibers result. In steady‐state measurements using microgap electrodes, a cast film of the nanofiber of 2 Amphi displays far better photoconducting properties than that of the microfiber of 2 Lipo. Flash‐photolysis time‐resolved microwave conductivity measurements, in conjunction with transient absorption spectroscopy, clearly indicate that the nanofiber of 2 Amphi intrinsically allows for better carrier generation and transport properties than the microfibrous assembly of 2 Lipo.
Effects of the isoflavonoid biochanin A on the transport of mitoxantronein vitroandin vivo
Authors: An Guohua , Morris Marilyn E. 
Published: June 2010

AbstractThe aim of our study was to investigate the effect of biochanin A on the accumulation and transport of mitoxantrone in breast cancer resistance protein (BCRP)‐expressing normal cells and its impact on the pharmacokinetics (PK) and tissue distribution of mitoxantrone. In accumulation studies, the intracellular level of mitoxantrone was significantly increased in the presence of 2.5 or 25 µMof biochanin A in both murine and human BCRP‐expressing Madin‐Darby canine kidney (MDCK) cells, with no effect in corresponding MDCK/Mock cells. In bi‐directional transport studies, thePapp,B‐Avalue of mitoxantrone with biochanin A co‐treatment was much lower (6.66±0.84×10−7 cm/s) than that in the absence of biochanin A (21.4±4.14×10−7 cm/s), indicating inhibition of Bcrp1‐mediated efflux. To evaluate whether ourin vitroresults might translate into anin vivointeraction, mitoxantrone PK and tissue distribution, with and without co‐administration of biochanin A, was investigated. In contrast to ourin vitroresults, biochanin A (10 mg/kg, i.v.) had no impact on the concentration of mitoxantrone in plasma and most tissues collected (brain, heart, liver and lung). Surprisingly, the concentrations of mitoxantrone in spleen and kidney were even decreased when biochanin A was co‐administered. Interestingly, it was found that the intracellular fluorescence of mitoxantrone was decreased 31.9% when co‐incubated with 10 µMbiochanin A in P‐glycoprotein (P‐gp) expressing MCF‐7/ADR cells, indicating potential P‐gp stimulation. The species difference of the inhibitory effect of biochanin A on BCRP, the extensive metabolism of biochanin A, as well as the stimulation effect of biochanin A on P‐gp, may contribute to thisin vitro–in vivodisconnect. Copyright © 2010 John Wiley & Sons, Ltd.
Methylnitrosourea induces neural progenitor cell apoptosis and microcephaly in mouse embryos
Authors: Komada Munekazu , Fujiyama Fusako , Yamada Shigehito , Shiota Kohei , Nagao Tetsuji 
Published: June 2010

AbstractBACKGROUND: Prenatal exposure to methylnitrosourea (MNU), an alkylating agent, induces microcephaly in mice. However, its pathogenetic mechanism has not been clarified, especially that in the development of the cerebral cortex. METHODS: ICR mice were treated with MNU at 10 mg/kg intraperitoneally on day 13.5 or 15.5 of gestation, and the embryos were observed histologically 24 hr after treatment with MNU or at term. To clarify the pathogenesis of microcephaly and histological changes, especially apoptosis, neurogenesis, and neural migration/positioning, we performed histological analysis employing a cell‐specific labeling experiment using thymidine‐like substances (BrdU, CldU, and IdU) and markers of neurons/neural stem cells. RESULTS: Histological abnormalities of the dorsal telencephalon, and the excessive cell death of proliferative neural progenitor/stem cells were noted in the MNU‐treated embryos. The highest frequencies of cell death occurred at 36 hr after MNU treatment, and little or no neurogenesis was observed in the ventricular zone of the dorsal telencephalon. Abnormality of the radial migration was caused by the reduction of radial fibers in the radial glias. Birth‐date analysis revealed the abnormal positioning of neurons and aberrant lamination of the cerebral cortex. CONCLUSIONS: Our data suggest that prenatal exposure to MNU induces the excessive cell death of neural precursor/stem cells, and the defective development of the cerebral cortex, resulting in microcephalic abnormalities. Birth Defects Res (Part B) 89:213–222, 2010. © 2010 Wiley‐Liss, Inc.
A comparison of the effects of prenatal exposure of CD‐1 mice to three imidazolium‐based ionic liquids
Authors: Bailey Melissa M. , Jernigan Peter L. , Henson Megan B. , Sturdivant John , Rasco Jane F. , Lovich Ashley N. , Lockhard Jarrett E. , Hough Whitney L. , Di Bona Kristin R. , Beaird Janis , Sherrill Jonathan , Swatloski Richard P. , Rogers Robin D. , Hood Ronald D. 
Published: June 2010

AbstractBACKGROUND: Ionic liquids (ILs; salts with melting points below 100°C) exhibit wide liquid ranges, non‐flammability, and thermal stability among other properties. These unique salts are best known as “green” alternatives to traditional volatile organic solvents, which are utilized in both academia and industry. Our current study compares the developmental toxicity potential of three representative ionic liquids, with various chain lengths: 1‐ethyl‐3‐methylimidazolium chloride ([C2mim]Cl), 1‐butyl‐3‐methylimidazolium chloride ([C4mim]Cl), and 1‐decyl‐3methylimidazolium chloride ([C10mim]Cl). METHODS: From gestation days (GD) 6‐16, mated CD‐1 mice were orally dosed with one of the following: 1,000, 2,000, or 3,000 mg/kg/day [C2mim]Cl; 113, 169, or 225 mg/kg/day [C4mim]Cl; 50, 75, or 100 mg/kg/day [C10mim]Cl; or the vehicle only. Dams were sacrificed on GD 17, and their litters were examined for adverse effects. RESULTS: Fetal weight was significantly decreased in the two highest dosage groups exposed to [C4mim]Cl and [C10mim]Cl in comparison with their controls, but the [C2mim]Cl treated groups were not affected. An apparent teratogenic effect was associated with both [C4mim]Cl and [C10mim]Cl, as the offspring exhibited certain uncommon morphological defects. However, the incidences of malformations were low and no correlation between incidence and dosage could be made. No morphological defects were observed in any of the [C2mim]Cl‐treated groups, despite maternal morbidity at the highest dosage level. CONCLUSIONS: This study indicates that [C4mim]Cl and [C10mim]Cl may have adverse effects on development at high maternal exposures and strongly supports the supposition that the toxicity of imidazolium‐based ILs is influenced by alkyl chain length. Birth Defects Res (Part B) 89:233–238, 2010. © 2010 Wiley‐Liss, Inc.
Cooperation and cheating in microbial exoenzyme production – Theoretical analysis for biotechnological applications
Authors: Schuster Stefan , Kreft Jan‐Ulrich , Brenner Naama , Wessely Frank , Theißen Günter , Ruppin Eytan , Schroeter Anja 
Published: June 2010

AbstractThe engineering of microorganisms to produce a variety of extracellular enzymes (exoenzymes), for example for producing renewable fuels and in biodegradation of xenobiotics, has recently attracted increasing interest. Productivity is often reduced by “cheater” mutants, which are deficient in exoenzyme production and benefit from the product provided by the “cooperating” cells. We present a game‐theoretical model to analyze population structure and exoenzyme productivity in terms of biotechnologically relevant parameters. For any given population density, three distinct regimes are predicted: when the metabolic effort for exoenzyme production and secretion is low, all cells cooperate; at intermediate metabolic costs, cooperators and cheaters coexist; while at high costs, all cells use the cheating strategy. These regimes correspond to the harmony game, snowdrift game, and Prisoner's Dilemma, respectively. Thus, our results indicate that microbial strains engineered for exoenzyme production will not, under appropriate conditions, be outcompeted by cheater mutants. We also analyze the dependence of the population structure on cell density. At low costs, the fraction of cooperating cells increases with decreasing cell density and reaches unity at a critical threshold. Our model provides an estimate of the cell density maximizing exoenzyme production.
Downhill binding energy surface of the barnase–barstar complex
Authors: Wang Ling , Siu Shirley W. I. , Gu Wei , Helms Volkhard 
Published: June 2010

AbstractWe have employed biased molecular dynamics simulations in explicit solvent to characterize the one‐dimensional potential of mean force for the dissociation process of the barnase–barstar protein–protein complex. Unbinding of barstar from wild‐type barnase was compared with dissociation from four charge‐deletion mutants of barnase. Interestingly, we find in all cases that unbinding of barnase and barstar is an uphill process on a smooth, tilted energy landscape. The total free energy difference between the dissociated and bound state was similar for wild‐type barnase–barstar and for the R87A mutant of barnase. The values for the three other mutant barnase mutants K27A, R59A, and R83Q were only about half as much. Besides, we have analyzed the conformational dynamics of important residues at the barnase–barstar interface. In the bound state, their conformational fluctuations are reduced relatively to the free state because of the formation of intermolecular contacts. Interestingly, we find that some residues also show decreased mobility at intermediate stages of the unbinding process suggesting that these residues may be involved in the first contacts being formed on binding. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 977–985, 2010.
Prevalence of the fibrinogen β‐chain, angiotensin‐converting enzyme and plasminogen activator inhibitor‐1 polymorphisms in Costa Rican young adults with thrombotic disease
Authors: Hidalgo Andrea , Salazar‐Sanchez Lizbeth , Cartin Mayra , Mendez Max , Arauz Jorge , Parajeles Alexander 
Published: June 2010

AbstractThrombotic disease is a multifactorial condition that involves both classical and genetic risk factors. We studied the association between the classical risk factors of hypertension and smoking, and polymorphisms on the genes of the angiotensin‐converting enzyme (ACE), the β‐chain of fibrinogen (FG), and the plasminogen activator inhibitor‐1 (PAI‐1) in patients with venous and arterial thrombosis. The present investigation is a retrospective case–control study. A total of 340 participants were analyzed, including 162 patients and 178 healthy controls. Hypertension and smoking showed a significant association with thrombotic disease (p < 0.05) but FG level was found significant risk factor only for the venous thrombosis (VT) group (p < 0.04). Significant differences between thrombotic groups were found for the studied polymorphisms of PAI‐1 (p < 0.0014), but for both FG β‐chain gene polymorphisms, none of the molecular analyses showed a positive sample for any mutating allele (p > 0.05). For the ACE polymorphism, the I allele present a protective effect in the general thrombotic group. This is one of the first reports in a Latin‐American population dealing with these molecular markers and thrombotic diseases. Copyright © 2010 John Wiley & Sons, Ltd.
Structure Determination of the Top‐Loop of the Conserved 3′‐Terminal Secondary Structure in the Genome of Flaviviruses
Authors: Lescrinier Eveline , Dyubankova Natalia , Nauwelaerts Koen , Jones Roger , Herdewijn Piet 
Published: June 2010

AbstractTo what extent small differences in RNA sequences (mutations) can have a profound impact on biology remains an intriguing question. This effect can be studied by using untranslated RNA regions as a model. We have studied the influence of mutations on the structure of an RNA hairpin that occurs in the 3′‐untranslated region (UTR) of Flaviviridae, and is known to have a large impact on the vector dependency of flaviviruses. Three related RNA sequences were studied by NMR spectroscopy. The selected sequences represent each one of the three clusters in the flavivirus genes (mosquito‐borne, tick‐borne, and no‐known‐vector viruses). A new strategy was used to obtain chemical shift signatures of carbonyl atoms in unlabeled uridine nucleobases to characterize their involvement in hydrogen bonding. Clear differences occur in the structures and stacking pattern of the three RNA hairpins. The observed differences cannot be predicted based on sequence analysis. A different biology can be correlated with a different RNA tertiary structure. The underlying biological mechanism, however, remains to be studied.
Functions of Genes and Enzymes Involved in Phenalinolactone Biosynthesis
Authors: Daum Martina , Schnell Hans‐Jörg , Herrmann Simone , Günther Andreas , Murillo Renato , Müller Rolf , Bisel Philippe , Müller Michael , Bechthold Andreas 
Published: June 2010

AbstractPhenalinolactones are novel terpene glycoside antibiotics produced by Streptomyces sp. Tü6071. Inactivation of three oxygenase genes (plaO2, plaO3 and plaO5), two dehydrogenase genes (plaU, plaZ) and one putative acetyltransferase gene (plaV) led to the production of novel phenalinolactone derivatives (PL HS6, PL HS7, PL HS2 and PL X1). Furthermore, the exact biosynthetic functions of two enzymes were determined, and their in vitro activities were demonstrated. PlaO1, an FeII/α‐ketoglutarate‐dependent dioxygenase, is responsible for the key step in γ‐butyrolactone formation, whereas PlaO5, a cytochrome P450‐dependent monooxygenase, catalyses the 1‐C‐hydroxylation of phenalinolactone D. In addition, stable isotope feeding experiments with biosynthetic precursors shed light on the origin of the carbons in the γ‐butyrolactone moiety.
Marine Molecular Machines: Heterocyclization in Cyanobactin Biosynthesis
Authors: McIntosh John A. , Schmidt Eric W. 
Published: June 2010

AbstractNatural products that contain amino‐acid‐derived (Cys, Ser, Thr) heterocycles are ubiquitous in nature, yet key aspects of their biosynthesis remain undefined. Cyanobactins are heterocyclic ribosomal peptide natural products from cyanobacteria, including symbiotic bacteria living with marine ascidians. In contrast to other ribosomal peptide heterocyclases that have been studied, the cyanobactin heterocyclase is a single protein that does not require an oxidase enzyme. Using this simplifying condition, we provide new evidence to support the hypothesis that these enzymes are molecular machines that use ATP in a product binding or orientation cycle. Further, we show that both protease inhibitors and ATP analogues inhibit heterocyclization and define the order of biochemical steps in the cyanobactin biosynthetic pathway. The cyanobactin pathway enzymes, PatD and TruD, are thiazoline and oxazoline synthetases.