bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cobalt‐induced oxidant stress in cultured endothelial cells: Prevention by ascorbate in relation to HIF‐1α
Authors: Qiao Huan , Li Liying , Qu Zhi‐chao , May James M. 
Published: April 2009

AbstractEndothelial cells respond to hypoxia by decreased degradation of hypoxia‐inducible factor 1α (HIF‐1α), accumulation of which leads to increased transcription of numerous proteins involved in cell growth and survival. Ascorbic acid prevents HIF‐1α stabilization in many cell types, but the physiologic relevance of such effects is uncertain. Given their relevance for angiogenesis, endothelial cells in culture were used to evaluate the effects of ascorbate on HIF‐1α expression induced by hypoxia and the hypoxia mimic cobalt. Although EA.hy926 cells in culture under oxygenated conditions did not contain ascorbate, HIF‐1α expression was very low, showing that the vitamin is not necessary to suppress HIF‐1α. On the other hand, hypoxia‐ or cobalt‐induced HIF‐1α expression/stabilization was almost completely suppressed by what are likely physiologic intracellular ascorbate concentrations. Increased HIF‐1α expression was not associated with significant changes in expression of the SVCT2, the major transporter for ascorbate in these cells. Cobalt at concentrations sufficient to stabilize HIF‐1α both oxidized intracellular ascorbate and induced an oxidant stress in the cells that was prevented by ascorbate. Whereas the interaction of ascorbate and cobalt is complex, the presence of physiologic low millimolar concentrations of ascorbate in endothelial cells effectively decreases HIF‐1α expression and protects against cobalt‐induced oxidant stress. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Tandem multimer expression of angiotensin I‐converting enzyme inhibitory peptide in Escherichia coli
Authors: Fida Hasan M. , Kumada Yoichi , Terashima Masaaki , Katsuda Tomohisa , Katoh Shigeo 
Published: April 2009

AbstractIt is common for small tandem peptide multimer genes to be indirectly inserted into expression vectors and fused with a protein tag. In this study, a multimer of the tandem angiotensin I‐converting enzyme inhibitory peptide (ACE‐IP) gene was directly transferred to a commercially available vector and the designed gene was expressed as a repeated peptide in Escherichia coli BL21(DE3)pLysS. The process further developed in our study was the construction of six‐repeated ACE‐IP synthetic genes and their direct insertion. Protein expression in inclusion bodies was confirmed by SDS‐PAGE and Western blot. Acid hydrolysis of inclusion bodies produced single‐unit peptides through cleavage of the aspartyl‐prolyl bonds. This cleaved recombinant peptide (rACE‐IP) was purified using immuno‐affinity chromatography followed by reversed phase‐HPLC. 105–115 mg of the lyophilized recombinant peptide was obtained from 1 L E. coli culture. In vitro biological activity of rACE‐IP was indistinguishable from that of the natural peptide produced by hydrolysis in artificial gastric juice or by acidic hydrolysis. The rACE‐IP prepared by recombinant DNA technology and solid‐phase synthesis methods showed a similar IC50. This strategy could be used for the expression of important peptides, which have N‐terminal proline (P) and C‐terminal aspartic acid residues (D) for commercial applications, e.g. functional foods and drinks.
Structural, thermodynamic, and kinetic properties of Gramicidin analogue GS6 studied by molecular dynamics simulations and statistical mechanics
Authors: Zanetti‐Polzi Laura , Anselmi Massimiliano , D'Alessandro Maira , Amadei Andrea , Di Nola Alfredo 
Published: April 2009

AbstractGramicidin S (GS) analogues belong to an important class of cyclic peptides, characterized by an antiparallel double‐stranded β‐sheet structure with Type II′ β‐turns. Such compounds can be used as model systems to understand the folding/unfolding process of β‐hairpins and more in general of β‐structures. In the present study, we specifically investigate the folding/unfolding behavior of the hexameric Gramicidin S analogue GS6 by using all‐atoms molecular dynamics (MD) simulations at different temperatures, coupled to a statistical mechanical model based on the Quasi Gaussian Entropy theory. Such an approach permits to describe the structural, thermodynamic, and kinetic properties of the peptide and to quantitatively characterize its folding/unfolding transitions. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 1154–1160, 2009.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
A folded and functional synthetic PA1b: An interlocked entomotoxic miniprotein
Authors: Da Silva Pedro , Strzepa Anna , Jouvensal Laurence , Rahioui Isabelle , Gressent Frédéric , Delmas Agnès F. 
Published: April 2009

AbstractPA1b (Pea Albumin 1, subunit b) is a hydrophobic, 37‐amino acid miniprotein isolated from pea seeds (Pivum sativum), crosslinked by three interlocked disulfide bridges, signature of the ICK (inhibitory cystine‐knot) family. It acts as an entomotoxic factor against major insect pests in stored crops and vegetables, making it a promising bioinsecticide. Here we report an efficient and simple protocol for the production of large quantities of highly pure, biologically active synthetic PA1b. The features of PA1b oxidative refolding revealed the off‐pathway products and competitive aggregation processes. The efficiency of the oxidative folding can be significantly improved by using hydrophobic alcoholic cosolvents and decreasing the temperature. The homogeneity of the synthetic oxidized PA1b was established by reversed‐phase HPLC. The correct pairing of the three disulfide bridges, as well as the three‐dimensional structure of synthetic PA1b was assessed by NMR. Synthetic PA1b binds to microsomal proteins from Sitophilus oryzae with a Kd of 8 nM, a figure quite similar to that determined for PA1b extracted from its natural source. Moreover, the synthetic miniprotein was as potent as the extracted one towards the sensitive strains of weevils. Our findings will open the way to the production of PA1b analogues by chemical means to an in‐depth understanding of the PA1b mechanism of action. © 2009 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 436–444, 2009.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Specific labeling with potent radiolabels alters the uptake of cell‐penetrating peptides
Authors: Walther Cornelia , Ott Ingo , Gust Ronald , Neundorf Ines 
Published: April 2009

AbstractRadiolabeled peptides play an important role in radiopharmacy not only as tumor markers but also as transport vectors. Therefore, cell‐penetrating peptides (CPP) may serve as very effective delivery tools, as well. Recently, CPP based on the human hormone calcitonin (hCT) have been developed. Especially, branched hCT‐peptide sequences turned out to have highly efficient internalization capacities. Labeling these peptides with radionuclides would generate promising new tools for imaging and therapy applications in radiopharmacy. However, the influence of the metal complexation on the internalization capacity of CPP has not been elucidated yet in detail. In this study we quantified the uptake of Ga‐DOTA modified hCT‐carrier peptides in HeLa cells by using atomic absorption spectroscopy (AAS) and compared the results to the uptake of fluorescently‐labeled peptides. Interestingly, we measured different uptake rates depending on the attached label. Unexpectedly, modification with a Ga‐DOTA complex can have tremendous effects on the uptake efficiency. The results of these studies support the need of detailed analysis of each carrier peptide/cargo construct, especially in the field of metal complex modified CPP. © 2009 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 445–451, 2009.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Particle concentration and yield stress of biomass slurries during enzymatic hydrolysis at high‐solids loadings
Authors: Roche Christine M. , Dibble Clare J. , Knutsen Jeffrey S. , Stickel Jonathan J. , Liberatore Matthew W. 
Published: April 2009

AbstractEffective and efficient breakdown of lignocellulosic biomass remains a primary barrier for its use as a feedstock for renewable transportation fuels. A more detailed understanding of the material properties of biomass slurries during conversion is needed to design cost‐effective conversion processes. A series of enzymatic saccharification experiments were performed with dilute acid pretreated corn stover at initial insoluble solids loadings of 20% by mass, during which the concentration of particulate solids and the rheological property yield stress (τy) of the slurries were measured. The saccharified stover liquefies to the point of being pourable (τy ≤ 10 Pa) at a total biomass conversion of about 40%, after roughly 2 days of saccharification for a moderate loading of enzyme. Mass balance and semi‐empirical relationships are developed to connect the progress of enzymatic hydrolysis with particle concentration and yield stress. The experimental data show good agreement with the proposed relationships. The predictive models developed here are based on established physical principles and should be applicable to the saccharification of other biomass systems. The concepts presented, especially the ability to predict yield stress from extent of conversion, will be helpful in the design and optimization of enzymatic hydrolysis processes that operate at high‐solids loadings. Biotechnol. Bioeng. 2009; 104: 290–300 © 2009 Wiley Periodicals, Inc.
Interplay between light intensity, chlorophyll concentration and culture mixing on the hydrogen production in sulfur‐deprived Chlamydomonas reinhardtii cultures grown in laboratory photobioreactors
Authors: Giannelli Luca , Scoma Alberto , Torzillo Giuseppe 
Published: April 2009

AbstractRelationships between light intensity and chlorophyll concentration on hydrogen production were investigated in a sulfur‐deprived Chlamydomonas reinhardtii culture in a laboratory scale photobioreactor (PBR) equipped with two different stirring devices. In the first case, the culture was mixed using a conventional magnetic stir bar, while in the second it was mixed using an impeller equipped with five turbines. Experiments were carried out at 70 and 140 µmol photons m−2 s−1 in combination with chlorophyll concentrations of 12 and 24 mg L−1. A high light intensity (140 µmol photons m−2 s−1, supplied on both sides of the PBR) in combination with a low chlorophyll concentration (12 mg L−1) inhibited the production of hydrogen, in particular in the culture mixed with the stir bar. An optimal combination for hydrogen production was found when the cultures were exposed to 140 µmol photons m−2 s−1 (on both sides) and 24 mg L−1 of chlorophyll. Under these conditions, the hydrogen production output rate reached about 120 mL L−1 in the culture mixed with the stir bar, and rose to about 170 mL L−1 in the one mixed with the impeller. These outputs corresponded to a mean light conversion efficiency of 0.56% and 0.81%, respectively. However, the efficiency increased to 1.08% and 1.64%, respectively, when maximum hydrogen rates were considered. The better performance of the dense cultures mixed with an impeller was mainly attributed to an intermittent illumination pattern to which the cells were subjected (time cycles within 50–100 ms) which influenced the hydrogen production (1) directly, by providing the PSII with a higher production of electrons for the hydrogenase and (2) indirectly, through a higher synthesis of carbohydrates. The fluid dynamics in the PBR equipped with the impeller was characterized. The better mixing state achieved in the PBR of the new configuration makes it a useful tool for studying the hydrogen production process involving photosynthetic microorganisms, and provides a better insight into the physiology of the process. Biotechnol. Bioeng. 2009; 104: 76–90 © 2009 Wiley Periodicals, Inc.
Causes of shear sensitivity of the toxic dinoflagellate Protoceratium reticulatum
Authors: Rodríguez J. J. Gallardo , Mirón A. Sánchez , Camacho F. García , García M. C. Cerón , Belarbi E. H. , Chisti Y. , Grima E. Molina 
Published: April 2009

AbstractDinoflagellates have proven extremely difficult to culture because they are inhibited by low‐level shear forces. Specific growth rate of the toxic dinoflagellate Protoceratium reticulatum was greatly decreased compared with static control culture by intermittent exposure to a turbulent hydrodynamic environment with a bulk average shear rate that was as low as 0.3 s−1. Hydrodynamic forces appeared to induce the production of reactive oxygen species (ROS) within the cells and this caused peroxidation of cellular lipids and ultimately cell damage. Exposure to damaging levels of shear rate correlated with the elevated level of lipoperoxides in the cells, but ROS levels measured directly by flow cytometry did not correlate with shear induced cell damage. This was apparently because the measured level of ROS could not distinguish between the ROS that are normally generated by photosynthesis and the additional ROS produced as a consequence of hydrodynamic shear forces. Continuously subjecting the cells to a bulk average shear rate value of about 0.3 s−1 for 24‐h caused an elevation in the levels of chlorophyll a, peridinin and dinoxanthin, as the cells apparently attempted to counter the damaging effects of shear fields by producing pigments that are potential antioxidants. In static culture, limitation of carbon dioxide produced a small but measureable increase in ROS. The addition of ascorbic acid (0.1 mM) to the culture medium resulted in a significant protective effect on lipid peroxidation, allowing cells to grow under damaging levels of shear rates. This confirmed the use of antioxidant additives as an efficient strategy to counter the damaging effects of turbulence in photobioreactors where shear sensitive dinoflagellates are cultivated. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Effect of periplasmic nitrate reductase on diauxic lag of Paracoccus pantotrophus
Authors: Durvasula Kiranmai , Jantama Kaemwich , Fischer Kyle , Vega Adrian , Koopman Ben , Svoronos Spyros A. 
Published: April 2009

AbstractParacoccus pantotrophus expresses two nitrate reductases—membrane bound nitrate reductase (Nar) and periplasmic nitrate reductase (Nap). In growth experiments with two denitrifying species (Paracoccus pantotrophus and Alcaligenes eutrophus) that have both Nap and Nar and two species (Pseudomonas denitrificans and Pseudomonas fluorescens) with Nar only, it was found that diauxic lag is shorter for bacteria that express Nap. In P. pantotrophus, napEDABC encodes the periplasmic nitrate reductase. To analyze the effect of Nap on diauxic lag, the nap operon was deleted from P. pantotrophus. The growth experiments with nap− mutant resulted in increased diauxic lag when switched from aerobic to anoxic respiration, suggesting Nap is responsible for shorter lags and helps in adaptation to anoxic metabolism after transition from aerobic conditions. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
An undergraduate fuzzy logic control lab using a line following robot
Authors: Ibrahim Dogan , Alshanableh Tayseer 
Published: April 2009

AbstractFuzzy logic controllers have gained popularity in the past few decades with highly successful implementation in many fields. Fuzzy logic enables designers to control complex systems more effectively than traditional methods. Teaching students fuzzy logic in a laboratory can be a time‐consuming and an expensive task. This paper presents a low‐cost educational microcontroller‐based tool for fuzzy logic controlled line following mobile robot. The robot is used in the second year of undergraduate teaching in an elective course in the department of computer engineering of the Near East University. Hardware details of the robot and the software implementing the fuzzy logic control algorithm are given in the paper. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 639–646, 2011
Cover Picture: A Pan‐Specific Inhibitor of the Polo‐Box Domains of Polo‐like Kinases Arrests Cancer Cells in Mitosis (ChemBioChem 7/2009)
Authors: Reindl Wolfgang , Yuan Juping , Krämer Andrea , Strebhardt Klaus , Berg Thorsten 
Published: April 2009

AbstractThe cover picture shows the small molecule Poloxipan, a pan‐specific inhibitor of polo‐like kinases (Plks), and its effects on human cancer cells. Most inhibitors of protein kinases such as Plk1, which is a key player in mitosis, inhibit the enzyme ATP‐binding pocket. Due to the conserved nature of the ATP‐binding pocket in protein kinases, this approach is frequently associated with specificity problems. In addition to their catalytic domain, polo‐like kinases contain a unique protein–protein interaction domain dubbed “polo‐box domain”, which is used by the enzymes to bind to their respective intracellular anchoring sites. On p. 1145 ff. of this issue, Berg, Strebhardt et al. explore the concept of inhibiting Plk1 by targeting the function of its polo‐box domain with Poloxipan, and find that the molecule induces mitotic arrest accompanied by a characteristic cellular phenotype called “chromosome congression defects”. This phenotype is represented by failure of one or more chromosomes to congress to the metaphase plate of mitotic cells, and is distinct from the phenotype observed with ATP‐competitive inhibitors of Plk1.magnified image
Use of interlock fibered detachable coils for occlusion of collaterals, coronary artery fistulae, and patent ductus arteriosus
Authors: Seltzer Sharon , Aboulhosn Jamil , Levi Daniel S. 
Published: April 2009

AbstractObjective: To investigate the utility of Interlocking Detachable Coils™ (IDC) for transcatheter occlusion of vascular communications in congenital heart disease. Background: The IDC can be delivered in a retractable fashion through hydrophilic Renegade™ microcatheters. They incorporate thrombogenic synthetic fibers and cost less than comparable neurovascular coils. They are ideally suited for use in many forms of congenital heart disease. Methods: A retrospective review of all patients catheterized during the initial 18‐month period of IDC availability at our institution was performed. Interlock coils were only used if traditional methods could not be used easily and safely. All congenital patients in whom IDC were used are described. Results: A total of 61 coils were deployed in 17 patients with various vessels not amenable to treatment with conventional coils. Coils were used in aortopulmonary collaterals (n = 7), veno‐venous collaterals (n = 9), patent ductus arteriosus (n = 3), and coronary artery fistulae (CAF) (n = 2). Operators were able to control coils and withdraw into the catheter for repositioning without difficulty. Thirteen of 21 vessels demonstrated immediate occlusion. All late angiograms have demonstrated complete occlusion of all vessels, with one exception requiring reintervention. One coil migrated from a large CAF and was easily retrieved with a snare. No serious complications occurred. All patients had an uneventful postcatheterization course. Conclusions: Transcatheter vascular coil embolization with IDCs can be performed safely and effectively in a variety of circumstances. © 2009 Wiley‐Liss, Inc.
Experimental evaluation of the JenaClip transcatheter aortic valve
Authors: Lauten Alexander , Ferrari Markus , Petri Alexander , Ensminger Stephan M. , Gummert Jan F. , Boudjemline Younes , Schubert Harald , Schumm Julia , Hekmat Khosro , Schlosser Markus , Figulla Hans R. 
Published: April 2009

AbstractObjective:Transcatheter techniques of aortic valve replacement are a treatment option for valvular heart disease in high‐risk surgical candidates. We evaluated a self‐expanding valve system with a novel mechanism of fixation in an experimental setting in an acute animal model and ex vivo in aortic root specimens.Method:A self‐expanding nitinol stent containing a pericardial tissue valve was implanted in a transapical approach in 15 sheeps. The valve was introduced under fluoroscopic guidance through a 22F sheath by means of a specially designed delivery catheter. Deployment was performed on the beating heart without cardiopulmonary bypass or rapid ventricular pacing and facilitated by positioning feelers anchoring the device to the native aortic cusps. To investigate release and anchoring of the device during retrograde implantation, the stent was also implanted in aortic root specimens obtained from an autopsy series.Results:In animal experiments, stent deployment was primarily successful in 12 (80%) animals. Positioning feelers facilitated implantation by confirming the correct implantation plane of the stent and anchoring to the native aortic cusps. If primary location was not satisfactory the stent was retracted into the catheter and repositioned. After successful implantation no significant changes of hemodynamics were observed. Two animals (13%) developed ventricular fibrillation early in this experimental series due to displacement of one positioning element into a coronary ostium, major regurgitation was observed in two animals. Ex vivo evaluation of the device in aortic root specimens proved feasibility of stent release and leaflet fixation; ex vivo implantation was successful in all cases.Conclusion:.In this study, we demonstrate feasibility of a leaflet‐fixation device in nondiseased aortic valves. The JenaClip provides an effective concept of fixation with positioning feelers that allows exact positioning without outflow obstruction and anchoring the valve to the native leaflets. Further studies are necessary to investigate this concept in diseased aortic valves. © 2009 Wiley‐Liss, Inc.
Thrombosis of an extracardiac fontan tunnel: Combined treatment of thrombolysis and stenting
Authors: Rauch Ralf , Sieverding Ludger , Hofbeck Michael 
Published: April 2009

AbstractObstruction of the so‐called Fontan tunnel represents a life‐threatening complication and requires immediate intervention. We describe the successful use of prolonged thrombolysis with rt‐PA, allowing stent placement in an extracardiac tunnel in a 7‐year‐old boy. © 2009 Wiley‐Liss, Inc.
A premounted stent that can be implanted in infants and re‐dilated to 20 mm: Introducing the Edwards Valeo Lifestent
Authors: Stern Herbert J. , Baird Christopher W. 
Published: April 2009

AbstractIntravascular stenting (IS) for vascular stenoses in congenital heart disease provides superior gradient relief and angiographic results over balloon angioplasty (BA) alone. The advantages of IS, however, are difficult to apply to infants, toddlers, and small children due to technical challenges in placing large, long sheaths and the risk of creating future stenoses in stents that cannot be re‐dilated to keep pace with somatic growth. This report highlights the Edwards premounted re‐dilatable biliary stent, which was safely placed in four infants and small children with excellent hemodynamic and angiographic results. Bench testing revealed the stent has adequate radial strength and can be re‐dilated to a maximal diameter of 20 mm. © 2009 Wiley‐Liss, Inc.