bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐density transfection with HEK‐293 cells allows doubling of transient titers and removes need for a priori DNA complex formation with PEI
Authors: Backliwal Gaurav , Hildinger Markus , Hasija Vivek , Wurm Florian M. 
Published: August 2007

AbstractRecombinant proteins are of great commercial and scientific interest. Yet, most production methods in mammalian cells involve the time‐ and labor‐consuming step of creating stable cell lines. Production methods based on transient gene expression are advantageous in terms of speed and versatility; yet, depending on the transfection protocol, transient transfection faces some bottlenecks such as a priori complex formation, limitations in terms of transfection and production media used and the need for medium exchange prior to and/or after transfection. Published protocols for transfection of suspension‐adapted HEK‐293 cells with polyethyleneimine have shown great promise in overcoming some of these bottlenecks, but still require a priori complex formation for optimal yields and limit the choice of transfection and production media. Here, we report successful in situ transfection of suspension‐adapted HEK‐293 cells with 25‐kDa linear polyethyleneimine at densities up to 20 × 106 cells/mL in complex media followed by production at lower cell densities (1 × 106 cells/mL). After concentrating cells to such high densities, transfection of HEK‐293 cells becomes possible in most commonly used media and is not restricted to a specific medium. Furthermore, there is no need to make transfection complexes a priori, a step that prevents inline sterile filtration of the DNA bulk for transfection, an important consideration when scaling processes up to 100 or 1,000 L. Finally, transfecting HEK‐293 cells at high density in complex media is superior to existing transfection protocols and doubles yields of recombinant protein obtainable by transient gene expression. Biotechnol. Bioeng. 2008;99: 721–727. © 2007 Wiley Periodicals, Inc.
Maximizing productivity of chromatography steps for purification of monoclonal antibodies
Authors: Tugcu Nihal , Roush David J. , Göklen Kent E. 
Published: August 2007

AbstractThe large scale production of monoclonal antibodies presents a challenge to design efficient and cost effective downstream purification processes. We explored a two stage resin screening approach to identify the best candidates to be utilized for the platform purification of monoclonal antibodies. The study focused on commercially available affinity resins including Protein A, mimetic and mixed‐mode interaction resins as well as ion exchangers used in polishing steps. An initial screening using pure proteins was followed by a final screening where selected resins were utilized for the purification of MAbs in complex mixtures. Initial screenings aimed to measure the theoretical upper limit for dynamic binding capacity (DBC) at 1% breakthrough and productivity. We confirmed that DBC of affinity, mimetic and mixed‐mode resins was a strong function of the linear velocity used for loading. Productivities >27 g/(L‐h), were obtained for rProtein A FF, Mabselect and Prosep rA Ultra at 2 min residence time. For the cation exchangers, we identified UNOsphere S and Fractogel SO3 as the best candidates for our purification based on DBC. For anion exchangers operated in flowthrough mode, Q Sepharose XL and UNOsphere Q were selected from the initial screening based on DBC and resolution of IgG from BSA. Finally, a three step purification scheme was implemented using the selected affinity and ion exchangers for the purification of IgG from complex feedstocks. We found that Mabselect followed by UNOsphere Q and UNOsphere S provided the best purification scheme for our applications based on productivity. Biotechnol. Bioeng. 2008;99: 599–613. © 2007 Wiley Periodicals, Inc.
Effect of femtomolar concentrations of hormones on insulin binding by Tetrahymena, as a function of time
Authors: Csaba G. , Kovács P. , Pállinger Éva 
Published: August 2007

AbstractThe unicellular ciliate Tetrahymena, contains and binds hormones, characteristic of vertebrates. Earlier experiments demonstrated the effect of extremely low concentrations of hormones. In the present experiments, the effect of various hormones (endorphin, serotonin, histamine, insulin and epidermal growth factor [EGF]) in 10−15 M, or oxytocin, gonadotropin at 0.001 IU concentrations) on the binding of FITC‐insulin was studied by using flow cytometry and confocal microscopy, after 1, 5, 15, 30 and 60 min. Six of the seven hormones promptly decreased the cells' hormone binding capacity, the exception being EGF, and in four cases (endorphin, serotonin, insulin and oxytocin) the reduction was enormous. The decreased binding was durable. However, in the case of endorphin and oxytocin after 30 min, and in the case of serotonin after 60 min the binding returned to the control level. In the case of oxytocin after 60 min, binding significantly surpassed the control level. Histamine returned to the control level after 15 min, but after that the binding became even lower. EGF provoked special behaviour: it increased hormone binding after 30 and 60 min. The results call attention to the extreme sensitivity of Tetrahymena receptors to hormonal inductions and to its quick response ability. Copyright © 2007 John Wiley & Sons, Ltd.
Multimarker Approach to Risk Stratification Among Patients with Advanced Chronic Heart Failure
Authors: Yin Wei‐Hsian , Chen Jaw‐Wen , Feng An‐Ning , Lin Shing‐Jong , Young Shing 
Published: August 2007

AbstractBackground:Cardiac troponin I (cTnI), N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) and high‐sensitivity C‐reactive protein (hsCRP) each predict adverse cardiac events in chronic heart failure (CHF). However, little is known about the utility of these novel biomarkers of CHF in combination.Hypothesis:We hypothesized that simultaneous assessment of the three biomarkers would enable clinicians to stratify risk more effectively among patients with advanced CHF.Methods:Measurements of the biomarkers were performed on 152 patients with symptomatic advanced CHF. Major adverse cardiac events during a median follow‐up period of 186 days were determined.Results:Univariate and multivariate analysis revealed that elevations of each biomarker were significant predictors of clinical outcome independently of clinical variables. When patients were categorized on the basis of the number of elevated biomarkers, patients with one, two and three elevated biomarkers respectively had a 2.7‐(p = 0.125), 8.6‐ (p < 0.0001) and 23.4‐(p < 0.0001) fold increase in the risk of adverse events.Conclusions:Simultaneous measurement of cTnI, hsCRP, and NT‐proBNP could provide complementary information and a simple multimarker strategy that categorizes the patients with advanced CHF based on the number of elevated biomarkers, allowing rapid risk stratification in these patients. Copyright © 2007 Wiley Periodicals, Inc.
Design, Synthesis, and Pharmacological Evaluation of Mefloquine‐Based Ligands as Novel Antituberculosis Agents
Authors: Mao Jialin , Wang Yuehong , Wan Baojie , Kozikowski Alan P. , Franzblau Scott G. 
Published: August 2007

AbstractTuberculosis (TB) is presently regarded as one of the most dangerous infective diseases worldwide and one of the major AIDS‐associated infections. To shorten the current treatment regimen, there is an urgent need to identify new anti‐TB agents which are active against both replicating TB (R‐TB) and nonreplicating TB (NRP‐TB). Mefloquine, a well‐known antimalarial drug was found to possess reasonable activity against NRP‐TB, and accordingly, 30 new analogues were synthesized and evaluated for their anti‐TB activity against Mycobacterium tuberculosis H37Rv. As the target of mefloquine in Mycobacterium tuberculosis remains unknown, we resorted to modifying mefloquine in a variety of chemically convenient ways, which led us in turn to the active hydrazone 10 a. Further modifications of 10 a led to compound 7 f, with an improved anti‐TB activity/selectivity profile with both less cytotoxicity and less predicted CNS side effects compared with mefloquine. The clear structure–activity relationships (SARs) derived from this study should facilitate our ultimate goal of identifying improved anti‐TB agents.
Non‐Resonance‐Assisted Hydrogen Bonding in Hydroxymethylene and Aminomethylene Cyclobutanones and Cyclobutenones and Their Nitrogen Counterparts.
Authors: Sanz Pablo , Mó Otilia , Yáñez Manuel , Elguero José 
Published: August 2007

AbstractThe characteristics of intramolecular hydrogen bonds (IMHB) have been systematically analyzed for a series of 32 different enols of derivatives of cyclobutane, cyclobutene, and cyclobutadiene bearing oxygen and nitrogen functionalities, at the B3LYP/6‐311+G(3df,2p)//B3LYP/6‐311+G(d,p) level of theory. In those cases where two tautomers (interconnected by a hydrogen shift through the IMHB) exist, tautomera, in which the HB‐donor group (YH) is attached to the four‐membered ring, is less stable than tautomerb, in which is the HB‐acceptor (X) is the one attached to the four‐membered ring. As expected the OH group behaves as a better HB‐donor than the NH2group and the CNH group as a better HB‐acceptor than the CO group, although the first effect clearly dominates. Accordingly, the expected IMHB strength follows the [donor, acceptor] trend: [OH,CNH]>[OH,CO]>[NH2,CNH]>[NH2,CO]. Quite unexpectedly, in all those compounds in which the functionality exhibiting the IMHB is unsaturated, the IMHB is weaker than in their saturated counterparts, verifying that the primary effect on the strength of the IMHB is the structure of the σ‐skeleton of the system. In the conjugated systems investigated here, the severe constraints imposed by the four‐membered ring force the HB donor and acceptor to be far apart and the IMHB is rather weak. These geometrical constraints are less severe for the saturated analogues and the IMHB becomes stronger, confirming that the characteristics of the σ‐skeleton, and not the resonance‐assisted hydrogen bond (RAHB) phenomenon, are the primary contributors to the strength of the IMHB in conjugated compounds.
The Outcome Questionnaire (OQ‐45) in a Dutch population: A cross‐cultural validation
Authors: de Jong Kim , Nugter M. Annet , Polak Marike G. , Wagenborg Johannes E. A. , Spinhoven Philip , Heiser Willem J. 
Published: August 2007

AbstractThe cross‐cultural validity of the Outcome Questionnaire (OQ) in the Dutch population has been examined by comparing the psychometric properties and equivalence in factor structure and normative scores of the Dutch OQ with the original American version. Data were collected from a university (n= 268), in a community (n= 810) and from three mental health care organizations (n= 1920). Results show that the psychometric properties of the Dutch OQ were adequate and similar to the original instrument. Some differences in equivalence were found though. In factor analysis, two additional factors were found: one consisting of social role items and another that reflected anxiety and somatic symptoms. Furthermore, normative scores were different for the Dutch and American samples, and this resulted in different cut‐off scores for estimating a clinically significant change in the Dutch population. Copyright © 2007 John Wiley & Sons, Ltd.
Correlations between cortisol level and internalizing disposition of young children are increased by selecting optimal sampling times and aggregating data
Authors: Li Ishien , Chiou Hua‐Huei , Shen Pao‐Sheng 
Published: August 2007

AbstractTo determine the optimal time for testing the association between personality traits and cortisol levels, and the number of sampling days needed for reliable results to be obtained for preschool‐aged children, ambulatory salivary sampling for cortisol was performed on 39 preschoolers at four different times for 10 consecutive school days. A repeated‐measure ANOVA revealed a significant day effect, time effect, and day by time interaction. Further tests of day effect revealed that within‐subject cortisol levels differed significantly in the early morning, early afternoon, and late afternoon cortisol data, but not in the late morning; group average levels of cortisol assessed in the early mornings are significantly different among the days, so are the ones measured in early and late afternoon. Mid‐afternoon cortisol levels showed the most significant day effect and the highest correlation with internalizing disposition. In addition, the probability of finding significant correlations between cortisol levels and internalizing disposition increased with a greater number of aggregated cortisol measures. The tentative conclusion is that to avoid under‐representation of the correlations between cortisol levels and personality variables, both sampling time selection and data aggregation are important. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 633‐639, 2007.
Microglial GLT‐1 is upregulated in response to herpes simplex virus infection to provide an antiviral defence via glutathione
Authors: Persson Mikael , Brantefjord Mona , Liljeqvist Jan‐Åke , Bergström Tomas , Hansson Elisabeth , Rönnbäck Lars 
Published: August 2007

AbstractHerpes simplex virus (HSV) can enter the central nervous system and cause encephalitis (HSV‐1) or meningitis (HSV‐2). Microglia, the immunocompetent cells of the central nervous system, are potentially able to detect viral infections. Microglia have been shown to express the glutamate transporter GLT‐1 during pathological events, leading to increased microglial glutamate uptake and glutathione synthesis. This study aims to address the role of GLT‐1 and glutathione, a major antioxidant with antiviral properties, during HSV infections. Using neuron‐enriched mixed primary cultures from rat, it was found that microglia have higher resistance to HSV infections than neurons or astrocytes after 24 h incubation with HSV. Purified microglia in culture were used to further address this. It was found that microglia were able to detect HSV and responded by releasing tumor necrosis factor‐α (TNF‐α) and upregulating GLT‐1 after 24 h incubation with 1 PFU/cell HSV‐1 or HSV‐2. Furthermore, the microglial glutathione levels were not significantly diminished after 24 h. Inhibition of the microglial glutathione synthesis with 200 μM buthionine sulfoximide (BSO) led to significantly more infected cells after 24 h incubation with 1 PFU/cell HSV‐1 or HSV‐2. These data indicate that the higher resistance in microglia against HSV infections may be due to the expression of GLT‐1, which can maintain the glutathione levels and provide a mechanism for microglial self‐defense against HSV. © 2007 Wiley‐Liss, Inc.
Depressive symptoms in late life: associations with apathy, resilience and disability vary between young‐old and old‐old
Authors: Mehta Mona , Whyte Ellen , Lenze Eric , Hardy Susan , Roumani Yazan , Subashan Perera , Huang Wennie , Studenski Stephanie 
Published: August 2007

AbstractObjectivePrior research has found that disability and apathy are associated with late‐life depression. However, the effect of age on these associations in “late‐life,” an ambiguous term encompassing all individuals typically older than 60 years, has not been examined. We investigated the association of depression with disability, apathy and resilience across the age range of late‐life.MethodsOne hundred and five community‐dwelling elderly with moderate levels of disability were assessed using the Geriatric Depression Scale (GDS), Hardy‐Gill Resilience Scale, Starkstein Apathy Scale and IADL/ADL questionnaire. Multiple regression analysis was used to assess relationships between depression, disability, apathy and resilience, stratified by age (<80 vs. >80).ResultsIn the <80 year old subject group, resilience, apathy and disability scores (partial type III R2 = 11.1%, 10.4% and 12.8%, respectively) equally contributed to the variability of GDS score. In contrast, in the >80 year old subject group, apathy (partial type III R2 = 18.7%) had the greatest contribution to GDS score.ConclusionsIn elderly persons under age 80, resilience, apathy and disability all have relatively equal contributions to depression scores, whereas in those over age 80, depression is most highly correlated with apathy. These data suggest that depressive symptoms in elderly persons have different clinical features along the age spectrum from young‐old to old‐old. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of conditioning methods on the microtensile bond strength of phosphate monomer‐based cement on zirconia ceramic in dry and aged conditions
Authors: Amaral Regina , Özcan Mutlu , Valandro Luiz Felipe , Balducci Ivan , Bottino Marco Antonio 
Published: August 2007

AbstractThe objective of this study was to evaluate the durability of bond strength between a resin cement and aluminous ceramic submitted to various surface conditioning methods. Twenty‐four blocks (5 × 5 × 4 mm3) of a glass‐infiltrated zirconia–alumina ceramic (In‐Ceram Zirconia Classic) were randomly divided into three surface treatment groups: ST1—Air‐abrasion with 110‐μm Al2O3 particles + silanization; ST2—Laboratory tribochemical silica coating method (110‐μm Al2O3, 110‐μm silica) (Rocatec) + silanization; ST3—Chairside tribochemical silica coating method (30‐μm SiOx) (CoJet) + silanization. Each treated ceramic block was placed in its silicone mold with the treated surface exposed. The resin cement (Panavia F) was prepared and injected into the mold over the treated surface. Specimens were sectioned to achieve nontrimmed bar specimens (14 sp/block) that were randomly divided into two conditions: (a) Dry—microtensile test after sectioning; (b) Thermocycling (TC)—(6,000×, 5–55°C) and water storage (150 days). Thus, six experimental groups were obtained (n = 50): Gr1—ST1 + dry; Gr2—ST1 + TC; Gr3—ST2 + dry; Gr4—ST2 + TC; Gr5—ST3 + dry; Gr6—ST3 + TC. After microtensile testing, the failure types were noted. ST2 (25.1 ± 11) and ST3 (24.1 ± 7.4) presented statistically higher bond strength (MPa) than that of ST1 (17.5 ± 8) regardless of aging conditions (p < 0.0001). While Gr2 revealed the lowest results (13.3 ± 6.4), the other groups (21.7 ± 7.4–25. 9 ± 9.1) showed statistically no significant differences (two‐way ANOVA and Tukey's test, α = 0.05). The majority of the failures were mixed (82%) followed by adhesive failures (18%). Gr2 presented significantly higher incidence of ADHESIVE failures (54%) than those of other groups (p = 0.0001). Both laboratory and chairside silica coating plus silanization showed durable bond strength. After aging, air‐abrasion with 110‐μm Al2O3 + silanization showed the largest decrease indicating that aging is fundamental for bond strength testing for acid‐resistant zirconia ceramics in order to estimate their long‐term performance in the mouth. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Negative modulation of presynaptic activity by zinc released from schaffer collaterals
Authors: Takeda Atsushi , Fuke Sayuri , Tsutsumi Wataru , Oku Naoto 
Published: August 2007

AbstractThe role of zinc in excitation of Schaffer collateral‐CA1 pyramidal cell synapses is poorly understood. Schaffer collaterals stained with ZnAF‐2 or ZnAF‐2DA, a membrane‐impermeable or a membrane‐permeable zinc indicator, respectively, were treated by tetanic stimulation (200 Hz, 1 sec). Extracellular and intracellular ZnAF‐2 signals were increased in the stratum radiatum of the CA1, in which Schaffer collateral synapses exist. Both the increases were completely blocked in the presence of 1 mM CaEDAT, a membrane‐impermeable zinc chelator, suggesting that 1 mM CaEDTA is effective for chelating zinc released from Schaffer collaterals. The role of Schaffer collateral zinc in presynaptic activity was examined by using FM4‐64, a fluorescent indicator for vesicular exocytosis. The decrease in FM4‐64 signal during tetanic stimulation (10 Hz, 180 sec) was enhanced in Schaffer collaterals in the presence of 1 mM CaEDTA but suppressed in the presence of 5 μM ZnC12, suggesting that zinc released from Schaffer collaterals suppresses presynaptic activity during tetanic stimulation. When Schaffer collateral synapses stained with calcium orange AM, a membrane‐permeable calcium indicator, were regionally stimulated with 1 mM glutamate, calcium orange signal was increased in the CA1 pyramidal cell layer. This increase was enhanced in the presence of CaEDTA and attenuated in the presence of zinc. These results suggest that zinc attenuates excitation of Schaffer collateral synapses elicited with glutamate via suppression of presynaptic activity. © 2007 Wiley‐Liss, Inc.
Renewable Resources as Reinforcement of Polymeric Matrices: Composites Based on Phenolic Thermosets and Chemically Modified Sisal Fibers
Authors: Megiatto Jackson D. , Oliveira Franciéli B. , Rosa Derval S. , Gardrat Christian , Castellan Alain , Frollini Elisabete 
Published: August 2007

AbstractLignocellulosic materials can significantly contribute to the development of composites, since it is possible to chemically and/or physically modify their main components, cellulose, hemicelluloses and lignin. This may result in materials more stable and with more uniform properties. It has previously been shown that chemically modified sisal fibers by ClO2 oxidation and reaction with FA and PFA presented a thin coating layer of PFA on their surface. FA and PFA were chosen as reagents because these alcohols can be obtained from renewable sources. In the present work, the effects of the polymeric coating layer as coupling agent in phenolic/sisal fibers composites were studied. For a more detailed characterization of the fibers, IGC was used to evaluate the changes that occurred at the sisal fibers surface after the chemical modifications. The dispersive and acid‐base properties of untreated and treated sisal fibers surfaces were determined. Biodegradation experiments were also carried out. In a complementary study, another PFA modification was made on sisal fibers, using K2Cr2O7 as oxidizing agent. In this case the oxidation effects involve mainly the cellulose polymer instead of lignin, as observed when the oxidation was carried out with ClO2. The SEM images showed that the oxidation of sisal fibers followed by reaction with FA or PFA favored the fiber/phenolic matrix interaction at the interface. However, because the fibers were partially degraded by the chemical treatment, the impact strength of the sisal‐reinforced composites decreased. By contrast, the chemical modification of fibers led to an increase of the water diffusion coefficient and to a decrease of the water absorption of the composites reinforced with modified fibers. The latter property is very important for certain applications, such as in the automotive industry.magnified image
Coadsorption and Support‐Mediated Interaction of Ti Species with Ethyl Benzoate in MgCl2‐Supported Heterogeneous Ziegler‐Natta Catalysts Studied by Density Functional Calculations
Authors: Taniike Toshiaki , Terano Minoru 
Published: August 2007

AbstractWe have firstly examined how the presence of ethyl benzoate (EB) close to the Ti species affects its stability and charge density on single crystal MgCl2 (110) and (100) surfaces by periodic density functional calculations. The energetic modification upon the coadsorption of EB and the Ti species was quite slight on both the (110) and (100) surfaces, which implies the random placement of these adsorbents on the support. The electron transfer from EB to the support enhanced the electron negativity of the Ti species on the (110) surface. In contrast, the electron that was donated from EB to the support never moved into the Ti species on the (100) surface. These results suggest that the addition of EB into the catalyst system introduces coadsorption‐induced active sites selectively on the (110) surface.magnified image