bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lowering oxygen tension enhances the differentiation of mouse embryonic stem cells into neuronal cells
Authors: Mondragon‐Teran Paul , Lye Gary J. , Veraitch Farlan S. 
Published: May 2009

AbstractEmbryonic stem cells (ESC) are capable of proliferating indefinitely in vitro whilst retaining their ability to differentiate into cells of every adult lineage. Efficient, high yield processes, which direct differentiation of ESC to specific lineages, will underpin the development of cost‐effective drug screening and cell therapy products. The aim of this study was to investigate whether laboratory oxygen tension currently used for the neuronal differentiation of ESC was suboptimal resulting in inefficient process yields. An adherent monolayer protocol for the neuronal differentiation of mouse ESC (mESC) was performed in oxygen controlled chambers using a chemically defined media over an 8 day period of culture. When exposed to oxygen tensions more appropriate to in vivo neuronal development (2% O2), there was a 34‐fold increase in the yield of viable cells from the differentiation process. Low oxygen tension inhibited cell death during an early phase (48 to 96 h) and toward the end (120 to 192 h) of the process. The percentage of cells expressing neuronal markers was determined by flow cytometry, revealing a small rise in the βIII tubulin and a threefold increase in the MAP2 populations at 2% O2. The total increase in the yield of viable cells expressing neuronal markers was shown to be 55‐fold for βIII tubulin and 114‐fold for MAP2. In conclusion, this study revealed that low oxygen tension can be used to enhance the yield of neuronal cells derived from ESCs and has implications for the development of efficient, cost‐effective production processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
A robust method for the joint estimation of yield coefficients and kinetic parameters in bioprocess models
Authors: Vastemans V. , Rooman M. , Bogaerts Ph. 
Published: May 2009

AbstractBioprocess model structures that require nonlinear parameter estimation, thus initialization values, are often subject to poor identification performances because of the uncertainty on those initialization values. Under some conditions on the model structure, it is possible to partially circumvent this problem by an appropriate decoupling of the linear part of the model from the nonlinear part of it. This article provides a procedure to be followed when these structural conditions are not satisfied. An original method for decoupling two sets of parameters, namely, kinetic parameters from maximum growth, production, decay rates, and yield coefficients, is presented. It exhibits the advantage of requiring only initialization of the first subset of parameters. In comparison with a classical nonlinear estimation procedure, in which all the parameters are freed, results show enhanced robustness of model identification with regard to parameter initialization errors. This is illustrated by means of three simulation case studies: a fed‐batch Human Embryo Kidney cell cultivation process using a macroscopic reaction scheme description, a process of cyclodextrin‐glucanotransferase production by Bacillus circulans, and a process of simultaneous starch saccharification and glucose fermentation to lactic acid by Lactobacillus delbrückii, both based on a Luedeking‐Piret model structure. Additionally, perspectives of the presented procedure in the context of systematic bioprocess modeling are promising. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Adaptive remodeling of hypoplastic hemodialysis fistulas salvaged with angioplasty
Authors: Bittl John A. , von Mering Gregory O. , Feldman Robert L. 
Published: May 2009

AbstractObjectives: The aim of this study was to determine whether immature hemodialysis fistulas undergo flow‐induced adaptive remodeling after successful percutaneous angioplasty. Background: Approximately 50% of radiocephalic fistulas remain immature after surgery and cannot be used for hemodialysis. Small fistulas with anastomotic inflow stenoses may undergo salvage angioplasty, but the time course of outward remodeling after successful treatment has not been defined. Methods: Thirty‐two of 39 patients (82%) with inaccessible, hypoplastic radiocephalic fistulas underwent attempted salvage angioplasty of inflow stenoses involving the arteriovenous anastomoses. Twenty patients experienced salvage of their fistulas and successfully underwent hemodialysis (51%). Results: Eleven patients had serial angiographic procedures, which allowed paired sequential quantitative angiographic measurements of the fistulas to be made during a median follow‐up of 200 days (range 5–2,298 days). Fistula diameters increased from 4.5 ± 1.3 mm to 8.0 ± 2.5 mm (mean ± S.D.). The mean growth of the fistulas was 1.0 ± 0.9 mm per year. Conclusions: The mechanism of adaptive remodeling transforms nonmaturing hypoplastic autogenous fistulas into functioning accessible dialysis accesses after successful percutaneous transluminal angioplasty of inflow anastomotic stenoses. © 2009 Wiley‐Liss, Inc.
Catheter‐based closure of atrial septal defects in the oval fossa with the Amplatzer® device in patients in their first or second year of life
Authors: Fischer G. , Smevik B. , Kramer H.H. , Bjørnstad P.G. 
Published: May 2009

AbstractObjective: To assess feasibility, safety, and efficacy of the use of Amplatzer® occluders in closure of atrial septal defects (ASD) in children in the first 2 years of life. Background: Although scattered reports on such closure have been published, no agreement consists on the policy. Methods: In 654 patients of all ages, closure was achieved in 632 (96.6%). Data were analyzed retrospectively in all 71 children where an attempt had been made to close the ASD before their second birthday. Results: Median age and body weight were 17.2 months (range 3.9–23.8) and 10.0 kg (range 3.8–14.5), respectively. Median fluoroscopy time was 13.6 min and median device size 15 mm. Successful closure was achieved in 68 children (95.8%). Three times the procedure was aborted: in one, the device repeatedly straddled the septum; in the other two, a small left atrium restricted the movement of the left‐sided disc. One device embolized and was reimplanted after retrieval. One infant with multiple disorders died 6 days after closure from acute sepsis probably unrelated to the procedure. No other complications occurred. Only trivial shunts closing with time were registered during follow‐up. Symptomatic patients profited markedly from closure. Conclusion: The results and complications of ASD closure with the Amplatzer® device in patients in their first 2 years of life compare favorably with procedures in older patients, provided that the size of the septum and the dimensions in the left atrium are taken into consideration when selecting the size of the device. © 2009 Wiley‐Liss, Inc.
Impact of day versus night as intervention time on the outcomes of primary angioplasty for acute myocardial infarction
Authors: Uyarel Huseyin , Ergelen Mehmet , Akkaya Emre , Ayhan Erkan , Demirci Deniz , Gul Mehmet , Isık Turgay , Cicek Gokhan , Gunaydın Zeki Yuksel , Ugur Murat , Demirci Duygu Ersan , Turkkan Ceyhan , Erer Hatice Betul , Ozturk Recep , Yekeler Ibrahim 
Published: May 2009

AbstractBackground: Conflicting datas exist regarding the outcomes of primary percutaneous coronary intervention (PCI) for ST‐segment elevation myocardial infarction (STEMI) when the intervention is performed during night hours. Methods and Results: 2,644 consecutive patients with STEMI (mean age 56.7 ± 11.9, years, 2,188 male) undergoing primary PCI between October 2003 and March 2008 were retrospectively enrolled into this study (single high‐volume center: >3,000 PCIs/year). Day time was defined according to intervention between 08:00 am and 06:00 pm and night as intervention time between 06:00 pm and 08:00 am. 1,141 patients (43.2%) were treated during the day and 1,503 (56.8%) at night. The baseline characteristics of both groups were similar except for more frequent hypertension (42.6 vs. 36.5%; P = 0.002), women (19.7 vs. 15.4%; P = 0.003), and old (≥75y) patients (9.6 vs. 7.4; P = 0.046) in the day time group. Compared with those treated during night time, day time patients had longer angina‐reperfusion times (mean, 205 vs. 188 minutes, P = 0.016). Door‐to‐balloon times were similar (P = 0.87), and less than 90 minutes in both groups. There were no differences concerning clinical events and PCI success between the two groups. Hospital mortality was 6.1% during the day and 5.2% during the night (OR 0.98, 95% CI 0.7–1.36; P = 0.89). The median follow‐up time was 21 months. The Kaplan‐Meier survival plot for long‐term cardiovascular death was not different for both groups (P = 0.78). In‐hospital and long‐term cardiovascular mortality was also similar in shock and nonshock subgroups. Conclusions: Primary PCI can be performed safely during the night at a high‐volume PCI center with suitable and effective organization of cardiology department and catheterisation laboratory with 24 hours per day, 7 days per week onsite staffing. © 2009 Wiley‐Liss, Inc.
Comparison of the angiographic myocardial blush grade with delayed‐enhanced cardiac magnetic resonance for the assessment of microvascular obstruction in acute myocardial infarctions
Authors: Vicente J. , Mewton N. , Croisille P. , Staat P. , Bonnefoy‐Cudraz E. , Ovize M. , Revel, D. 
Published: May 2009

AbstractBackground: Both myocardial blush grade (MBG) and cardiac magnetic resonance (CMR) are imaging tools that can assess myocardial reperfusion after primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI). Objectives: We studied the relation between MBG and gadolinium‐enhanced CMR for the assessment of microvascular obstruction (MVO) in patients with acute ST‐elevated myocardial infarction (STEMI) treated by primary PCI. Material and Methods: MBG was assessed in 39 patients with initial TIMI 0 STEMI successfully treated by PCI, resulting in TIMI 3 flow grade and complete ST‐segment resolution. These MBG values were related to MVO determined by CMR, performed between 2 and 7 days after PCI. Left ventricular (LV) volumes were determined at baseline and at 6‐month follow‐up. Results: No statistical relation was found between MBG and MVO extent at CMR (P = 0.63). Regarding MBG 0 and 1 as a sign of MVO, the sensitivity and specificity of these scores were 53.8 and 75%, respectively. In this study, CMR determined MVO was the only significant LV remodeling predicting factor (β = 31.8; P = 0.002), whatever the MBG status was. Conclusion: MBG underestimates MVO after an optimal revascularization in AMI compared with CMR. This study suggests the superior accuracy of delayed‐enhanced magnetic resonance over MBG for the assessment of myocardial reperfusion injury that is needed in clinical trials, where the principal endpoint is the reduction of infarct size and MVO. © 2009 Wiley‐Liss, Inc.
Telescoping catheter technique for enlarged aortas
Authors: Anantharaman Rajaram , Obaid Daniel , Chase Alexander 
Published: May 2009

AbstractSelective coronary angiography in severely dilated ascending aorta is technically challenging and sometimes impossible. The Terumo “five‐in‐six” system uses an extra long 5Fr guide catheter in a standard 6Fr guide catheter, so that the tip of the 5Fr guide catheter protrudes beyond the tip of the 6Fr catheter allowing an extra reach. This system has been used successfully to advance balloon catheters across chronic total occlusions (Takahashi et al, Catheter Cardiovasc Interv 2004;63:452–456) and stent delivery beyond proximal obstruction point (Mamas et al, Catheter Cardiovasc Interv 2008;71:358–363). We describe the successful use of this system in an atraumatic manner for selective coronary angiography in a patient with a severely dilated ascending aorta. © 2009 Wiley‐Liss, Inc.
The Role of Water in Platinum‐Catalyzed Cycloisomerization of 1,6‐Enynes: A Combined Experimental and Theoretical Gas Phase Study
Authors: Baumgarten Sigrid , Lesage Denis , Gandon Vincent , Goddard Jean‐Philippe , Malacria Max , Tabet Jean‐Claude , Gimbert Yves , Fensterbank Louis 
Published: May 2009

AbstractPtII‐catalyzed cycloisomerization of a 1,6‐enyne proceeds quickly in CHCl3 at room temperature, and also in the gas phase. However, calculations predict a slow reaction, because of the formation of a very stable chelate that undergoes oxidative cyclization at a high energy cost. The electrophilic activation of the alkyne followed by nucleophilic attack of the double bond to generate a cyclopropyl carbene would lead to a faster reaction, but the decomplexation of the double bond to generate an unsaturated platinum species is also energetically disfavored. However, decomplexation can be envisaged if an adventitious molecule of water enters the coordination sphere of the metal. This crucial role of water in PtII‐catalyzed cycloisomerization of enynes, initially sensed some years ago (Echavarren et al., J. Am. Chem. Soc. 2001, 123, 10511) is now supported by mass spectrometry studies.
Laminar Drag Reduction in Hydrophobic Microchannels
Authors: Hao P.‐F. , Wong C. , Yao Z.‐H. , Zhu K.‐Q. 
Published: May 2009

AbstractThe apparent slip effects of laminar water flow in smooth hydrophobic microchannels and patterned hydrophobic microchannels were investigated. A series of experiments were performed to demonstrate the drag reductions for laminar water flow in hydrophobic microchannels. These microchannels were fabricated from silicon wafers using photolithography and were coated with hydrophobic octadecyltrichlorosilane (OTS). To generate a larger drag reduction, the patterned hydrophobic microchannels were fabricated to allow the liquid to flow over a region of trapped air in the cavity between the microridges. With the geometrical dimensions used, pressure drop reductions ranging from 10 to 30 % were found in the smooth microchannels and patterned microchannels. The pressure drop reduction was shown to increase with increasing microridge spacing and decreasing microchannel width. Using micro‐particle image velocimetry (PIV), we measured an apparent slip velocity at the wall of approximately 8 % of the centerline velocity, yielding a slip length of approximately 2 μm in the smooth hydrophobic microchannel. Theoretically, the analytical solution derived for three‐dimensional flow in a rectangular duct is presented to predict the slip velocity and slip length at the wall based on the pressure drop measurement. These results are in agreement with the experimental data obtained using micro‐PIV.
Determining Critical Process Parameters and Process Robustness in Preparative Chromatography – A Model‐Based Approach
Authors: Degerman M. , Westerberg K. , Nilsson B. 
Published: May 2009

AbstractThis paper presents a model‐based method to aid in the process validation for the purification of pharmaceutical drugs. The critical process parameters are identified by simulating process disturbances, and this information is then used to determine if the process control space is robust. Simulations are chosen to analyze the entire control space to also find nonlinearities and interaction effects between the process disturbances, which are used to determine where in the control space the critical quality attributes are the lowest, i.e., the worst case scenario. The real process conditions are estimated by running simulations according to plausible probability distributions using Latin hypercube sampling. The probability of batch failure can be estimated from this and it is shown that the worst case scenario is improbable for most cases. This information can help in planning validation experiments or determine which critical process parameters need a tighter control. Three case studies are used to illustrate the usefulness of the methods. It was found that the main critical process parameters in all three case studies were variations in the modifier concentrations, for example, salt in ion‐exchange chromatography and hydrophobic interaction chromatography, and the organic modifier in reversed‐phase chromatography.
Does a chiral alcohol really racemize when its OH group is protected with Boyer's reaction?
Authors: Fraschetti Caterina , Speranza Maurizio , Filippi Antonello 
Published: May 2009

AbstractChiral reactants have been employed for assessing the real stereochemistry of the BiBr3‐catalyzed synthesis of benzylic ethers, a very useful reaction for protecting alcoholic groups. The results of this investigation are in clear contrast with the conclusions of previous studies (Boyer et al., Tetrahedron 2001;57:1917–1921). Indeed, chiral GC‐MS analysis of the ethereal products gives unequivocal evidence of the complete racemization of the benzylic moiety and the complete retention of configuration of the protected alcoholic substrate. Such findings make BiBr3 a powerful and stereochemically preservative catalyst for benzylation of chiral alcohols, and a potential candidate for orthogonal protecting group strategies applicable to polyhydroxy compounds. Chirality 2010. © 2009 Wiley‐Liss, Inc.
Correlation between structures of chiral polymers and their efficiency for chiral resolution by crystallization
Authors: Menahem Tali , Pravda Martin , Mastai Yitzhak 
Published: May 2009

AbstractIn this work, we describe the correlation between chiral polymer structures, particularly α‐helical and random coil conformations, and their efficiency as chiral resolving agents in crystallization processes. A set of chiral block copolymers based on polyethylene oxide with chiral glutamic acid oligopeptide segments (PEG113‐b‐(+)‐(S)‐Glu20) were synthesized and employed as additives in the crystallization of rac‐threonine. CD spectroscopy demonstrates that structures of chiral polymers could be switched between a helical and a disordered random coil by pH. The effect of these polymers at different conformations on the crystallization kinetics, crystal morphology, and chiral resolution of rac‐threonine is reported. Our study demonstrates that only chiral polymers with α‐helical conformations of the chiral segment are effective as additives for chiral resolution throughout crystallization. Overall, our results provide useful guidelines for the selection and design of chiral polymer additives that will act efficiently for chiral resolution by crystallization. Chirality 2009. © 2009 Wiley‐Liss, Inc.
Structure and absolute configuration of ginkgolide B characterized by IR‐ and VCD spectroscopy
Authors: Andersen Niels H. , Christensen Niels Johan , Lassen Peter R. , Freedman Teresa B.N. , Nafie Laurence A. , Strømgaard Kristian , Hemmingsen Lars 
Published: May 2009

AbstractExperimental and calculated (B3LYP/6‐31G(d)) vibrational circular dichroism (VCD) and IR spectra are compared, illustrating that the structure and absolute configuration of ginkgolide B (GB) may be characterized directly in solution. A conformational search for GB using MacroModel and subsequent DFT optimizations (B3LYP/6‐31G(d)) provides a structure for the lowest energy conformer which agrees well with the structure determined by X‐ray diffraction. In addition, a conformer at an energy of 7 kJ mol−1 (B3LYP/6‐311+G(2d,2p)) with respect to the lowest energy conformer is predicted, displaying different intramolecular hydrogen bonding. Differences between measured and calculated IR and VCD spectra for GB at certain wavenumbers are rationalized in terms of interactions with solvent, intermolecular GB‐GB interactions, and the potential presence of more than one conformer. This is the first detailed investigation of the spectroscopic fingerprint region (850−1300 cm−1) of the natural product GB employing infrared absorption and VCD spectroscopy. Chirality, 2010. © 2009 Wiley‐Liss, Inc.
Modelling and simulation for one‐day cricket
Authors: Swartz Tim B. , Gill Paramjit S. , Muthukumarana Saman 
Published: May 2009

AbstractThis article is concerned with the simulation of one‐day cricket matches. Given that only a finite number of outcomes can occur on each ball that is bowled, a discrete generator on a finite set is developed where the outcome probabilities are estimated from historical data involving one‐day international cricket matches. The probabilities depend on the batsman, the bowler, the number of wickets lost, the number of balls bowled and the innings. The proposed simulator appears to do a reasonable job at producing realistic results. The simulator allows investigators to address complex questions involving one‐day cricket matches. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Testing heteroscedasticity in nonlinear and nonparametric regressions
Authors: Zheng Xu 
Published: May 2009

AbstractThis article presents new nonparametric tests for heteroscedasticity in nonlinear and nonparametric regression models. The tests have an asymptotic standard normal distribution under the null hypothesis of homoscedasticity and are robust against any form of heteroscedasticity. A Monte Carlo simulation with critical values obtained from the wild bootstrap procedure is provided to asses the finite sample performances of the tests. A real application of testing interest rate volatility functions illustrates the usefulness of the tests proposed. The Canadian Journal of Statistics © 2009 Statistical Society of Canada
Myocardial Cleft, Crypt, Diverticulum, or Aneurysm? Does it Really Matter?
Authors: Afonso Luis , Kottam Anupama , Khetarpal Vipin 
Published: May 2009

AbstractMyocardial clefts are congenital abnormalities related to myocardial fiber or fascicle disarray that have been described in healthy volunteers as well as in the setting of hypertrophic cardiomyopathy. A cleft or crypt can be described as a discrete, approximately “V” shaped fissure extending into but confined by the myocardium, with a tendency to narrow or occlude in systole without local hypokinesia or dyskinesia. While little is known about the clinical significance of this entity, this report elaborates on the confounding terminology and differential diagnosis of this condition. Copyright © 2009 Wiley Periodicals, Inc.
Treatment of nonmuscle invading bladder cancer: Do physicians in the United States practice evidence based medicine?
Authors: Madeb Ralph , Golijanin Dragan , Noyes Katia , Fisher Susan , Stephenson Judith J. , Long Stacey R. , Knopf Joy , Lyman Gary H. , Messing Edward M. 
Published: May 2009

AbstractBACKGROUND:Phase 3 clinical trials performed primarily outside the US demonstrate that intravesical instillation of chemotherapy immediately after transurethral resection of the bladder (TURB) decreases cancer recurrence rates. The authors sought to determine whether US urologists have adopted this practice, and its potential effect on costs of bladder cancer (BC) care.METHODS:By using 1997‐2004 MEDSTAT claims data, the authors identified patients with newly diagnosed BC who underwent cystoscopic biopsy or TURB, and those who received intravesical chemotherapy within 1 day after TURB. Economic consequences of this treatment compared with TURB alone were modeled using published efficacy estimates and Medicare reimbursements. The authors used a time horizon of 3 years and assumed that this treatment was given for all newly diagnosed low‐risk BC patients.RESULTS:Between 1997 and 2004, the authors identified 16,748 patients with newly diagnosed BC, of whom 14,677 underwent cystoscopic biopsy or TURB. Of these, only 49 (0.33%) received same‐day intravesical instillation of chemotherapy. From 1997 through 2004, there has been little change in the use of this treatment. The authors estimated a 3‐year savings of $538 to $690 (10% to 12%) per patient treated with TURB and immediate intravesical chemotherapy compared with TURB alone, reflecting a yearly national savings of $19.8 to $24.8 million.CONCLUSIONS:Instillation of intravesical chemotherapy immediately after TURB has not been embraced in the US. Adopting this policy would significantly lower the cost of BC care. Cancer 2009. © 2009 American Cancer Society.