bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulmonary Endostatin Perinatally and in Lung Injury of the Newborn Infant
Authors: Janér Joakim , Andersson Sture , Haglund Caj , Lassus Patrik 
Published: December 2006

OBJECTIVE. Endostatin is a potent angiogenesis inhibitor. Angiogenesis is central for the development of the human lung. The role of endostatin in the development of the human lung and its connection to chronic lung disease remain unclear. We set out to study the role of endostatin in the developing human lung and in acute and chronic lung injury in the preterm infant.METHODS. Nine fetuses, 14 control neonates without primary lung disease, 14 preterm infants with respiratory distress syndrome, and 8 infants with bronchopulmonary dysplasia were included in the immunohistochemistry study. Tracheal aspirate-fluid samples of intubated very low birth weight infants during postnatal weeks 1 through 5 were analyzed with enzyme-linked immunosorbent assay.RESULTS. Endothelial cell staining was positive for endostatin in all 45 samples. Staining of epithelial cells (cuboidal, bronchiolar, and alveolar) was seen mostly in fetuses, as well as in infants with late respiratory distress syndrome and bronchopulmonary dysplasia. Staining in alveolar macrophages was most abundant in infants with late respiratory distress syndrome and bronchopulmonary dysplasia. Endostatin was expressed consistently in tracheal aspirate fluid, being highest during the first postnatal day. Higher endostatin concentrations correlated with parameters reflecting lower lung maturity.CONCLUSIONS. The pattern of pulmonary endostatin protein expression in immunohistochemistry and consistent endostatin protein appearance in tracheal aspirate fluid in human preterm infants indicate a role in the physiologic development of the lung. Preterm birth influences pulmonary endostatin protein expression, which may alter normal lung development and response to lung injury.
The influence of protons and zinc ions on the steady-state inactivation of Kv1.3 potassium channels
Authors: Teisseyre Andrzej , Mozrzymas Jerzy 
Published: December 2006

AbstractUsing the whole-cell patch-clamp technique, we investigated the influence of extracellular pH and zinc ions (Zn2+) on the steady-state inactivation of Kv1.3 channels expressed in human lymphocytes. The obtained data showed that lowering the extracellular pH from 7.35 to 6.8 shifted the inactivation midpoint (Vi) by 17.4 ± 1.12 mV (n = 6) towards positive membrane potentials. This shift was statistically significant (p < 0.05). Applying 100 μM Zn2+ at pH 6.8 further shifted the Vi value by 16.55 ± 1.80 mV (n = 6) towards positive membrane potentials. This shift was also statistically significant (p < 0.05). The total shift of the Vi by protons and Zn2+ was 33.95 ± 1.90 mV (n = 6), which was significantly higher (p < 0.05) than the shift caused by Zn2+ alone. The Zn2+-induced shift of the Vi at pH 6.8 was almost identical to the shift at pH = 7.35. Thus, the proton-and Zn2+-induced shifts of the Vi value were additive. The steady-state inactivation curves as a function of membrane voltage were compared with the functions of the steady-state activation. The total shift of the steady-state inactivation was almost identical to the total shift of the steady-state activation (32.01 ± 2.10 mV, n = 10). As a result, the “windows” of membrane potentials in which the channels can be active under physiological conditions were also markedly shifted towards positive membrane potentials. The values of membrane voltage and the normalised chord conductance corresponding to the points of intersection of the curves of steady-state activation and inactivation were also calculated. The possible physiological significance of the observed modulatory effects is discussed herein.
Lewis Acid‐Catalyzed Sequential Transformations: Straightforward Preparation of Functional Dihydropyridines
Authors: Vohra Ramandeep Kaur , Bruneau Christian , Renaud Jean‐Luc 
Published: December 2006

AbstractLewis acids catalyze the addition of β‐enaminoacrylates or β‐enaminones to α,β‐unsaturated aldehydes leading to substituted dihydropyridines in high yields under mild reaction conditions.
Internal Alkene Hydroaminations Catalyzed by Zirconium(IV) Complexes and Asymmetric Alkene Hydroaminations Catalyzed by Yttrium(III) Complexes
Authors: Kim Hyunseok , Kim Young Kwan , Shim Jun Hwan , Kim Misook , Han Mijung , Livinghouse Tom , Lee Phil Ho 
Published: December 2006

AbstractThe thiophosphinic amide 2 was prepared in 68 % yield by the reaction of 2,2‐dimethyl‐1,3‐propanediamine with diisopropylchlorophosphine followed by the addition of sulfur. Attachment of the proligand 2 to zirconium was achieved by direct metalation with Zr(NMe2)4 in benzene‐d6 or toluene‐d8 to afford complex 3 via elimination of dimethylamine. The neutral Zr(IV) complex 3 has been shown to be an effective precatalyst for intramolecular alkene hydroaminations that provide cyclic amines in good to excellent yields. A variety of chiral ligands (20, 22, 24, and 25–30) were prepared for asymmetric internal alkene hydroaminations. Metalation of chiral ligands to yttrium was accomplished with Y[N(TMS)2]3 in benzene‐d6 or toluene‐d8 to give complexes. Treatment of 7 with 5 mol % of 33 in benzene‐d6 (25 °C, 18 h) or toluene‐d8 (25 °C, 15 h) afforded 2,4,4‐trimethylpyrrolidine 14 in 95 % yield (61 % ee).
Autoradiographic localization of aromatic hydrocarbon receptor (AHR) in rhesus monkey ovary
Authors: Baldridge Monika G , Hutz Reinhold J. 
Published: December 2006

Abstract2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin (TCDD) is the most toxic congener of a large class of manmade pollutants that persist in the environment. TCDD exerts its toxic effects, in part, by binding to its receptor known as the aromatic hydrocarbon receptor (AHR). TCDD is estrogen modulatory and in some systems its receptor associates directly with estrogen receptors via co‐activator molecules. TCDD inhibits steroid synthesis in human ovarian granulosa cells and AHR is found in these cells. We have previously shown that AHR is found in whole rhesus monkey ovary, but have yet to establish its location. In the present study, we set out to show that radiolabeled TCDD binds to monkey ovarian follicles and that this binding is receptor mediated. Ovaries from Macaca mulatta were sectioned on a cryostat at 10 µ m; and sections were incubated with either control vehicle, 3H‐TCDD, or 3H‐TCDD plus alpha‐naphthoflavone (ANF), a known receptor‐blocking agent. Here, we show for the first time specific binding of TCDD to the granulosa cells of antral follicles and other regions of the rhesus monkey ovary. Our data indicate a 60‐fold increase in binding with 3H‐TCDD over that of control, and that this binding is reduced to the levels seen in controls with the addition of the competitive antagonist ANF. These findings support the hypothesis that TCDD directly affects primate ovarian function via the AHR. Am. J. Primatol. 69:681–691, 2007. © 2006 Wiley‐Liss, Inc.
Comparative in vitro degradation of the human hemorphin LVV‐H7 in mammalian plasma analysed by capillary zone electrophoresis and mass spectrometry
Authors: John Harald , Schulz Stefanie , Forssmann Wolf‐Georg 
Published: December 2006

AbstractThe human hemorphin LVV‐H7 (L32VVYPWTQRF41) is a hemoglobin‐β, ‐γ, ‐δ or ‐ε chain derived cationic decapeptide of the µ‐opioid receptor binding family. It exhibits potential pharmacological value relevant, for example, for blood pressure regulation, learning performance and Alzheimer's disease. The regulatory potency is strictly dependent on the length of the amino acid sequence which is sensitive towards proteinases from tissues and plasma. To analyse LVV‐H7 in vitro degradation in mammalian plasma, a novel multi‐component quantitative capillary zone electrophoretic (CZE) procedure was applied, combined with qualitative metabolite profiling by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). In all types of plasma, LVV‐H7 was N‐terminally truncated generating four metabolites (M1–M4) with an intact C‐terminus: M1 (V33VYPWTQRF41), M2 (V34YPWTQRF41), M3 (Y35PWTQRF41) and M4 (W37TQRF41). In EDTA plasma these degradation products were detected exclusively, whereas in citrate and heparin plasma four further metabolites appeared resulting from additional C‐terminal cleavage of the dipeptide R40F41: M5 (L32VVYPWTQ39), M6 (V33VYPWTQ39), M7 (V34YPWTQ39) and M8 (Y35PWTQ39). In the presence of selective proteinase inhibitors aminopeptidase M and angiotensin‐converting enzyme (for N‐ and C‐terminal truncation, respectively) were identified as plasma enzymes responsible for hemorphin degradation. Furthermore, striking inter‐mammalian species distinctions were detected revealing strongly differing degradation velocities but similar metabolite patterns. Copyright © 2007 John Wiley & Sons, Ltd.
Conformational changes upon calcium binding and phosphorylation in a synthetic fragment of calmodulin
Authors: Settimo Luca , Donnini Serena , Juffer André H. , Woody Robert W. , Marin Oriano 
Published: December 2006

AbstractWe have recently investigated by far‐UV circular dichroism (CD) the effects of Ca2+ binding and the phosphorylation of Ser 81 for the synthetic peptide CaM [54–106] encompassing the Ca2+‐binding loops II and III and the central α helix of calmodulin (CaM) (Arrigoni et al., Biochemistry 2004, 43, 12788–12798). Using computational methods, we studied the changes in the secondary structure implied by these spectra with the aim to investigate the effect of Ca2+ binding and the functional role of the phosphorylation of Ser 81 in the action of the full‐length CaM. Ca2+ binding induces the nucleation of helical structure by inducing side chain stacking of hydrophobic residues. We further investigated the effect of Ca2+ binding by using near‐UV CD spectroscopy. Molecular dynamics simulations of different fragments containing the central α‐helix of CaM using various experimentally determined structures of CaM with bound Ca2+ disclose the structural effects provided by the phosphorylation of Ser 81. This post‐translational modification is predicted to alter the secondary structure in its surrounding and also to hinder the physiological bending of the central helix of CaM through an alteration of the hydrogen bond network established by the side chain of residue 81. Using quantum mechanical methods to predict the CD spectra for the frames obtained during the MD simulations, we are able to reproduce the relative experimental intensities in the far‐UV CD spectra for our peptides. Similar conformational changes that take place in CaM [54–106] upon Ca2+ binding and phosphorylation may occur in the full‐length CaM. © 2006 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 373–385, 2007.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
Deglycosylation of ovalbumin prohibits formation of a heat‐stable conformer
Authors: de Groot Jolan , Kosters Hans A. , de Jongh Harmen H.J. 
Published: December 2006

AbstractTo study the influence of the carbohydrate‐moiety of ovalbumin on the formation of the heat‐stable conformer S‐ovalbumin, ovalbumin is deglycosylated with PNGase‐F under native conditions. Although the enzymatic deglycosylation procedure resulted in a complete loss of the ability to bind to Concavalin A column‐material, only in about 50% the proteins lost their complete carbohydrate moiety, as demonstrated by mass spectrometry and size exclusion chromatography. Thermal stability and conformational changes were determined using circular dichroism and differential scanning calorimetry and demonstrated at ambient temperature no conformational changes due to the deglycosylation. Also the denaturation temperature of the processed proteins remained the same (77.4 ± 0.4°C). After heat treatment of the processed protein at 55°C and pH 9.9 for 72 h, the condition that converts native ovalbumin into the heat‐stable conformer (S‐ovalbumin), only the material with the intact carbohydrate moiety forms this heat‐stable conformer. The material that effectively lost its carbohydrate moiety appeared fully denatured and aggregated due to these processing conditions. These results indicate that the PNGase‐F treatment of ovalbumin prohibits the formation and stabilization of the heat‐stable conformer S‐ovalbumin. Since S‐ovalbumin in egg protein samples is known to affect functional properties, this work illustrates a potential route to control the quality of egg protein ingredients. Biotechnol. Bioeng. 2007;97: 735–741. © 2006 Wiley Periodicals, Inc.
Scale‐up of enzymatic production of lactobionic acid using the rotary jet head system
Authors: Hua Ling , Nordkvist Mikkel , Nielsen Per Munk , Villadsen John 
Published: December 2006

AbstractEnzymatic oxidation of lactose to lactobionic acid (LBA) by a carbohydrate oxidase from Microdochium nivale was studied in a pilot‐scale batch reactor of 600 L working volume using a rotary jet head (RJH) for mixing and mass transfer (Nordkvist et al., 2003, Chem Eng Sci 58:3877–3890). Both lactose and whey permeate were used as substrate, air was used as oxygen source, and catalase was added to eliminate the byproduct hydrogen peroxide. More than 98% conversion to LBA was achieved. Neither enzyme deactivation nor enzyme inhibition was observed under the experimental conditions. The dissolved oxygen tension (DOT) was constant throughout the tank for a given set of operating conditions, indicating that liquid mixing was sufficiently good to avoid oxygen gradients in the tank. However, at a given oxygen tension measured in the tank, the specific rate of reaction found in the RJH system was somewhat higher than previously obtained in a 1 L mechanically stirred tank reactor (Nordkvist et al., 2007, in this issue, pp. 694–707). This can be ascribed to a higher pressure in the recirculation loop which is part of the RJH system. Compared to mechanically stirred systems, high values of the volumetric mass transfer coefficient, kLa, were obtained when lactose was used as substrate, especially at low values of the specific power input and the superficial gas velocity. kLa was lower for experiments with whey permeate than with lactose due to addition of antifoam. The importance of mass transfer and of the saturation concentration of oxygen on the volumetric rate of reaction was demonstrated by simulations. Biotechnol. Bioeng. 2007;97: 842–849. © 2006 Wiley Periodicals, Inc.
Oxidation of lactose to lactobionic acid by a Microdochium nivale carbohydrate oxidase: Kinetics and operational stability
Authors: Nordkvist Mikkel , Nielsen Per Munk , Villadsen John 
Published: December 2006

AbstractOxidation of lactose to lactobionic acid by a Microdochium nivale carbohydrate oxidase was studied. The Km‐value for lactose, obtained by a traditional enzymatic assay, was 0.066 mM at pH 6.4 and 38°C. The effect of oxygen on the enzymatic rate of reaction as well as the operational stability of the enzyme was studied by performing reactions at constant pH and temperature in a stirred tank reactor. Catalase was included in all reactions to avoid inhibition and deactivation of the oxidase by hydrogen peroxide. At pH 6.4 and 38°C, Km for oxygen was 0.97 mM, while the catalytical rate constant, kcat, was 94 s−1. Furthermore, we found that the operational stability of the oxidase was dependent on the type of base used for neutralization of the acid produced. Thus, when 2 M NaOH was used for neutralization of a reaction medium containing 50 mM phosphate buffer, significant deactivation of the oxidase was observed. Also, we found that the oxidase was protected against deactivation by base at high lactose concentrations. A simple model is proposed to explain the obtained results. Biotechnol. Bioeng. 2007;97: 694–707. © 2006 Wiley Periodicals, Inc.
Characterization of the localized hydrodynamic shear forces and dissolved oxygen distribution in sparged bioreactors
Authors: Koynov Athanas , Tryggvason Grétar , Khinast Johannes G. 
Published: December 2006

AbstractDetailed, high‐resolution numerical simulations of the bubbly flows, used for oxygen delivery and mixing in mammalian cell suspensions, have been performed. The hydrodynamics, shear and normal forces, mass transfer and mass transport from and around individual bubbles and bubble clusters were resolved for different operating conditions, that is, Weber, Morton, and Schmidt numbers. Suspended animal (e.g., mammalian, insect) cells are known to be susceptible to damage potentially leading to cell death, caused by hydrodynamic stresses and oxygen deprivation. Better knowledge of the magnitude of the shear forces and the extent of mixing of the dissolved oxygen in sparged bioreactors can have a significant impact on their future design and optimization. Therefore, the computed liquid‐phase velocity fields were used to calculate and compare the local shear in different types of single bubble wakes and in bubble clusters. Oxygen mass transfer and dissolved oxygen transport were resolved to examine oxygen supply to the cells in the different types of flows. Biotechnol. Bioeng. 2007;97: 317–331. © 2006 Wiley Periodicals, Inc.
Effect of siRNA nuclease stability on the in vitro and in vivo kinetics of siRNA‐mediated gene silencing
Authors: Bartlett Derek W. , Davis Mark E. 
Published: December 2006

AbstractSmall interfering RNA (siRNA) molecules achieve sequence‐specific gene silencing through the RNA interference (RNAi) mechanism. Here, live‐cell and live‐animal bioluminescent imaging (BLI) is used to directly compare luciferase knockdown by unmodified and nuclease‐stabilized siRNAs in rapidly (HeLa) and slowly (CCD‐1074Sk) dividing cells to reveal the impact of cell division and siRNA nuclease stability on the kinetics of siRNA‐mediated gene silencing. Luciferase knockdown using unmodified siRNAs lasts approximately 1 week in HeLa cells and up to 1 month in CCD‐1074Sk cells. There is a slight increase in the duration of luciferase knockdown by nuclease‐stabilized siRNAs relative to unmodified siRNAs after cationic lipid transfection, but this difference is not observed after electroporation. In BALB/cJ mice, a fourfold increase in maximum luciferase knockdown is observed after hydrodynamic injection (HDI) of nuclease‐stabilized siRNAs relative to unmodified siRNAs, yet the overall kinetics of the recovery after knockdown are nearly identical. By using a mathematical model of siRNA‐mediated gene silencing, the trends observed in the experimental data can be duplicated by changing model parameters that affect the stability of the siRNAs before they reach the cytosolic compartment. Based on these findings, we hypothesize that the stabilization advantages of nuclease‐stabilized siRNAs originate primarily from effects prior to and during internalization before the siRNAs can interact with the intracellular RNAi machinery. Biotechnol. Bioeng. 2007;97: 909–921. © 2006 Wiley Periodicals, Inc.
Quantitative analysis of EDC‐condensed DNA on vertically aligned carbon nanofiber gene delivery arrays
Authors: Mann David G.J. , McKnight Timothy E. , Melechko Anatoli V. , Simpson Michael L. , Sayler Gary S. 
Published: December 2006

AbstractVertically aligned carbon nanofibers (VACNFs) with immobilized DNA have been developed as a novel tool for direct physical introduction and expression of exogenous genes in mammalian cells. Immobilization of DNA base amines to the carboxylic acids on nanofibers can influence the accessibility and transcriptional activity of the DNA template, making it necessary to determine the number of accessible gene copies on nanofiber arrays. Polymerase chain reaction (PCR) and in vitro transcription (IVT) were used to investigate the transcriptional accessibility of DNA tethered to VACNFs by correlating the yields of both IVT and PCR to that of non‐tethered, free DNA. Yields of the promoter region and promoter/gene region of bound DNA plasmid were high. Amplification using primers designed to cover 80% of the plasmid failed to yield any product. These results are consistent with tethered, longer DNA sequences having a higher probability of interfering with the activity of DNA and RNA polymerases. Quantitative PCR (qPCR) was used to quantify the number of accessible gene copies tethered to nanofiber arrays. Copy numbers of promoters and reporter genes were quantified and compared to non‐tethered DNA controls. In subsequent reactions of the same nanofiber arrays, DNA yields decreased dramatically in the non‐tethered control, while the majority of tethered DNA was retained on the arrays. This decrease could be explained by the presence of DNA which is non‐tethered to all samples and released during the assay. This investigation shows the applicability of these methods for monitoring DNA immobilization techniques. Biotechnol. Bioeng. 2007;97: 680–688. © 2006 Wiley Periodicals, Inc.
Protein engineering of Acidovorax facilis 72W nitrilase for bioprocess development
Authors: Wu Shijun , Fogiel Arthur J. , Petrillo Kelly L. , Hann Eugenia C. , Mersinger Lawrence J. , DiCosimo Robert , O'Keefe Daniel P. , Ben‐Bassat Arie , Payne Mark S. 
Published: December 2006

AbstractHydroxycarboxylic acid monomers can be used to prepare industrially important polymers. Enzymatic production of such hydroxycarboxylic acids is often preferred to chemical production since the reactions are run at ambient temperature, do not require strongly acidic or basic reaction conditions, and produce the desired product with high selectivity at high conversion. However, native enzymes often do not perform desired reactions with the efficiency required for commercial applications. Protein engineering was used to significantly increase the specific activity of nitrilase from Acidovorax facilis 72W for the conversion of 3‐hydroxyvaleronitrile to 3‐hydroxyvaleric acid. Overexpression of engineered nitrilase enzymes in Escherichia coli, combined with immobilization of whole cells in alginate beads that can be recycled many times has facilitated the development of a commercially viable bioprocess for production of 3‐hydroxyvaleric acid. Biotechnol. Bioeng. 2007;97: 689–693. © 2006 Wiley Periodicals, Inc.
Enhancement of pyruvate production by osmotic‐tolerant mutant of Torulopsis glabrata
Authors: Liu Liming , Xu Qinglong , Li Yin , Shi Zhongpin , Zhu Yang , Du Guocheng , Chen Jian 
Published: December 2006

AbstractPyruvate production by Torulopsis glabrata was used as a model to study the mechanism of product inhibition and the strategy for enhancing pyruvate production. It was found that the concentration of cell growth and pyruvate deceased with the increase of NaCl and sorbitol concentrations. To enhance the osmotic stress resistance of the strain, an NaCl‐tolerant mutant RS23 was screened and selected through a pH‐controlled continuous culture with 70 g/L NaCl as the selective criterion. Compared with the parent strain, mutant RS23 could grow well on the medium containing 70 g/L NaCl or 0.6 mol/L sorbitol. Pyruvate concentration by the mutant strain RS23 reached 94.3 g/L at 82 h (yield on glucose 0.635 g/g) in a 7‐l fermentor with 150 g/L glucose as carbon source. Pyruvate concentration and yield of mutant RS23 were 41.1% and 11.1% higher than those of the parent strain, respectively. The strategy for enhancing pyruvate production by increasing osmotic stress resistance may provide an alternative approach to enhance organic acids production with yeast. Biotechnol. Bioeng. 2007;97: 825–832. © 2006 Wiley Periodicals, Inc.