bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Antiarrhythmic Agents for Atrial Fibrillation and Atrial Flutter: United States Drug Market Response as an Indicator of Acceptance
Authors: LaPointe Nancy M. Allen , Pamer Carol A. , Kramer Judith M. 
Published: May 2004

Objective. To determine how well dofetilide and Betapace AF (sotalol, approved solely for atrial fibrillation and atrial flutter), with their detailed dosing and monitoring guidelines for safety, were accepted into clinical practice during the 2 calendar years after their introduction.Methods and Results. We reviewed the number of new, refill, and total prescriptions of all antiarrhythmic agents in the United States from April 2000‐December 2001 to assess use of dofetilide and Betapace AF in the drug market. Both were prescribed very infrequently throughout the study period. In addition, the infrequent reported use of these drugs for patients with atrial fibrillation and flutter indicated poor acceptance of these agents by prescribing physicians. We speculated that the restricted distribution and required educational program for dofetilide, as well as the availability of generic sotalol products, may have discouraged physicians from prescribing both dofetilide and Betapace AF.Conclusion. A common goal for both the dofetilide risk‐management program and the creation of a sotalol product indicated solely for atrial fibrillation and atrial flutter was to provide safer treatment for patients with these arrhythmias. Unfortunately, limited penetration of dofetilide and Betapace AF into the U.S. market suggests that drugs without a risk‐management program or detailed dosing guidelines were more likely than dofetilide or Betapace AF to be selected for treatment of atrial fibrillation and atrial flutter.
Peritoneal Dialysis Fluid Concentrations of Linezolid in the Treatment of Vancomycin‐Resistant Enterococcus faecium Peritonitis
Authors: DePestel Daryl D. , Peloquin Charles A. , Carver Peggy L. 
Published: May 2004

Objective. To determine linezolid concentrations in peritoneal dialysis fluid after multiple oral doses of the drug in a 46‐year‐old man with vancomycin‐resistant Enterococcus faecium peritonitis who was undergoing peritoneal dialysis.Methods. After administration of oral linezolid 600 mg twice/day was started, peritoneal dialysis fluid was collected at the end of several 4‐ and 8‐hour dwell times and submitted for analysis of linezolid concentration. Before linezolid therapy was begun, and immediately after several peritoneal dialysis exchanges, 30 ml of expended peritoneal dialysis fluid was collected in a sterile container and immediately frozen at −70°C until analysis by high‐performance liquid chromatography.Results. Peritoneal dialysis concentrations of linezolid greater than 4 μg/ml were achieved after the first dose of linezolid and maintained after repeated doses. During the course of therapy, mean linezolid concentrations in peritoneal dialysis fluid tended to increase (mean 7.60 μg/ml, range 3.54–16.2 μg/ml). All assayed peritoneal dialysis samples demonstrated linezolid concentrations greater than 4 μg/ml at the end of 4‐ or 8‐hour dwell times, except for one level after a missed dose on linezolid treatment day 3. Duration of dwell times did not appear to correlate with linezolid concentrations.Conclusion. In this patient, linezolid 600 mg twice/day penetrated into peritoneal dialysis fluid at or above the concentrations necessary to treat common gram‐positive bacteria. Linezolid therapy is likely to have a role in peritoneal dialysis‐associated peritonitis based on its antimicrobial activity, pharmacokinetic properties, ease of administration, and tolerability.
The microdistribution of three uncommon freshwater gastropods in the drainage ditches of British grazing marshes
Authors: Watson Alisa M. , Ormerod S.J. 
Published: May 2004

Abstract
The gastropods Segmentina nitida, Anisus vorticulus and Valvata macrostoma occur in drainage ditches on grazing marshes that are now among the most threatened wetland systems in western Europe. Although each of these species is listed in the UK Red Data Book (RDB) and Biodiversity Action Plan, influences on their distribution are poorly understood.
2. To improve management information, the within‐channel distributions of the three snails were examined in 20 ditches in southeast England. Abundance, vegetation cover and other environmental factors were recorded across the ditch profile near the surface (<0.2m) and at depth (<0.15m from the benthos).
3. All three species were significantly more abundant near the surface than at depth. Below 0.6m, ditches had significantly reduced concentrations of dissolved oxygen (<0.6 mg L−1, <5% saturation), possibly sufficient to limit the occurrence of gastropods dependent wholly or partly on aqueous gas exchange.
4. There were no other systematic variations in abundance between the ditch margins and centre channel. However, across all ditches and samples in the survey, each species' abundance varied significantly with vegetation structure. S. nitida was most numerous where there was least open water and hence most vegetation, V. macrostoma among emergent stands and A. vorticulus in ditches with floating vegetation but few submerged plants.
5. These microdistributional data support large‐scale surveys in illustrating the potential importance of vegetation management for these snails; providing that other requirements are satisfied, ditch management could favour each RDB species by optimizing particular vegetation features. Apparent preferences for vegetation structure rather than particular channel locations suggest that refuges left during ditch clearance could be located anywhere in the ditch. Factors that reduce oxygen concentrations below 1mg L −1, such as eutrophication, might be detrimental.
Copyright © 2004 John Wiley & Sons, Ltd.
Development of a mammalian series‐fibered muscle
Authors: Paul Angelika C. , Sheard Philip W. , Duxson Marilyn J. 
Published: May 2004

AbstractThis study examines the processes by which multiply innervated, serially fibered mammalian muscles are constructed during development. We previously reported that primary myotubes of such a muscle, the guinea pig sternomastoid muscle, span from tendon to tendon and are innervated at each of the muscle's four innervation zones. Secondary myotubes form later, in association with each point of innervation (Duxson and Sheard, Dev. Dyn., 1995; 204:391–405). We now describe the further growth and development of the muscle. Secondary myotubes initially insert onto and grow along the primary myotube. However, as they reach a critical length, they encounter other secondary myotubes growing from serially adjacent innervation zones and may transfer their attachment(s) to these serially positioned secondary myotubes. Other secondary myotubes maintain attachment at one or both ends to their primary myotube. Thus, an interconnected network of primary and secondary myotubes is formed. Patterns of reactivity for cell adhesion molecules suggest that early attachment points between myotubes are the embryonic precursors of adult myomyonal junctions, characterized by the expression of α7Bβ1 integrin. Finally, the results show that secondary myotubes positioned near a tendon are generally longer than those lying in the mid belly of the muscle, and we suggest that the environment surrounding the tendinous zone may somehow stimulate myotube growth. Anat Rec Part A 278A:571–578, 2004. © 2004 Wiley‐Liss, Inc.
Kinetic analysis and modeling of firefly luciferase as a quantitative reporter gene in live mammalian cells
Authors: Ignowski Jolene M. , Schaffer David V. 
Published: May 2004

AbstractFirefly luciferase has proven to be a highly sensitive and quantitative reporter gene for studying gene delivery and regulation, and its recent use in live cells and organisms promises to further expand its utility. However, the intracellular behavior and properties of the enzyme are not well characterized. Specifically, information on the intracellular kinetics and stability of luciferase activity is necessary for real‐time luminescence counts from live cells to be quantitatively meaningful. Here, we report a dynamic analysis of luciferase activity in the context of living mammalian cells. We have determined the relative light units measured in living cells to be proportional to that found in cell lysate. We have also calculated the Km of luciferase in living cells to be ≈ 1 mM, a value much higher than the 10 μM found for pure enzyme in vitro. In addition, a 2‐hour half‐life of luciferase activity in live cells was measured in real time. Finally, we have modeled luciferase activity in live cells for the purposes of understanding and translating the luciferase signal into a more effective metric of gene expression and cell behavior. © 2004 Wiley Periodicals, Inc.
Method for determining oxygen consumption rates of static cultures from microplate measurements of pericellular dissolved oxygen concentration
Authors: Guarino Richard D. , Dike Laura E. , Haq Tariq A. , Rowley Jon A. , Pitner J. Bruce , Timmins Mark R. 
Published: May 2004

AbstractWe describe a simple protocol for determining the oxygen consumption of cells in static culture. The protocol is based on a noninvasive oxygen‐sensing microplate and a simple mathematical model derived from Fick's Law. The applicability of the model is confirmed by showing the correlation of computed oxygen consumption rate (OCR) values to actual cell densities ascertained by direct cell counting and/or MTT for HL60 and U937 cells cultured in suspension. Correlation between computed OCR and these other indications of cell number was quite good, as long as the cultures were not diffusion‐limited for oxygen. The impact of the geometric factors of media depth and well size were confirmed to be consistent with the model. Based on this demonstrated correlation, we also developed a simple, completely noninvasive algorithm for ascertaining the per‐cell oxygen utilization rate (OUR), which is the ratio of OCR to cell number, and a fundamental cell characteristic. This is accomplished by correlating the known seed densities to extrapolated determinations of OCR at time zero. Such determinations were performed for numerous cell types, in varying well sizes. Resulting OUR values are consistent with literature values acquired by far more painstaking methods, and ranged from <0.01 fmol·min−1·cell−1 for bacteria to 0.1–10 fmol·min−1·cell−1 for immortalized mammalian and insect cell lines to >10 fmol·min−1·cell−1 for primary hepatocytes. This protocol for determining OCR and OUR is extremely simple and broadly applicable and can afford rapid, informative, and noninvasive insight into the state of the culture. © 2004 Wiley Periodicals, Inc.
Insights into adenoviral vector production kinetics in acoustic filter‐based perfusion cultures
Authors: Henry Olivier , Dormond Edwige , Perrier Michel , Kamen Amine 
Published: May 2004

AbstractOne of the major limitations in the production of adenoviral vectors is the reduction in cell‐specific productivity observed for increasing cell density at infection in batch cultures. This observation strongly suggests some nutrient depletion and/or metabolite inhibition in the media. These limitations have been partially overcome through other feeding strategies, such as fed‐batch and sequential batch operations. To improve these results, we evaluated perfusion as a strategy to increase the volumetric productivity of HEK‐293 cell cultures, by allowing productive infection at higher cell densities. An acoustic cell separator was employed in consideration of the increased shear sensitivity of the cells during the infection phase. The effects of perfusion rate and cell density at infection on the production of a recombinant adenovirus expressing the GFP were investigated. The perfusion mode allowed successful infection at cell densities in the range of 2.4–3 × 106 cell/mL, while maintaining a similar cell specific productivity (17,900 ± 2400 VP/cell) to that of a batch infected at a low cell density (5 × 105 cell/mL). The highest virus concentrations (4.1 ± 0.6 × 1010 VP/mL) were attained for a feed rate of 2 vol/d and constituted a fivefold increase compared to a batch with medium replacement. Rapid assessment of the infection status was achieved through the use of on‐line monitoring of respiration, fluorescence, and biovolume. Analysis of the kinetics of nutrient consumption and metabolite production revealed that a reduction in specific productivity is correlated with reduced metabolic activity. © 2004 Wiley Periodicals, Inc.
Biphasic aqueous/organic biotransformation of acetaldehyde and benzaldehyde by Zymomonas mobilis pyruvate decarboxylase
Authors: Rosche Bettina , Breuer Michael , Hauer Bernhard , Rogers Peter L. 
Published: May 2004

AbstractZymomonas mobilis pyruvate decarboxylase (PDC) transformed acetaldehyde and benzaldehyde into (R)‐phenylacetylcarbinol (PAC), the precursor for the synthesis of ephedrine and pseudoephedrine. Organic solvents were screened for a biphasic biotransformation with the enzyme in an aqueous phase and the toxic substrates delivered through the organic phase. In the absence of substrates a second phase of 1‐pentanol, hexadecane or MTBE (methyl tertiary‐butyl ether) stabilized the PDC activity in comparison to a control without added solvent. Organic phase solvents for optimal PAC production had partitioning coefficient (log P) values between 0.8 and 2.8 (production of more than 8 mg PAC/ U PDC), however there was no correlation between enzyme stability and log P. Best PAC formation was observed with the eight tested alcohols, which in contrast to the other solvents allowed lower initial concentrations of toxic acetaldehyde (54–81 mM) in the aqueous phase. 1‐pentanol, 1‐hexanol, and isobutanol resulted in the highest specific PAC production of 11 mg PAC /U PDC. Without the addition of an organic phase, only 1.2 mg/U was formed. © 2004 Wiley Periodicals, Inc.
Preparation of single cells from aggregated Taxus suspension cultures for population analysis
Authors: Naill Michael C. , Roberts Susan C. 
Published: May 2004

AbstractA method for the isolation of single plant cells from Taxus suspension cultures has been developed for the analysis of single cells via rapid throughput techniques such as flow cytometry. Several cell wall specific enzymes, such as pectinase, pectolyase Y‐23, macerozyme, Driselase®, and cellulase were tested for efficacy in producing single cell suspensions. The method was optimized for single cell yield, viability, time, and representivity of aggregated cell cultures. The best combination for single cell isolation was found to be 0.5% (w/v) pectolyase Y‐23 and 0.04% (w/v) cellulase. High viability (>95%) and high yields of single cell aggregates (>90%) were obtained following 4 hours of digestion for four separate Taxus cell lines. In addition, methyl jasmonate elicitation (200 μM) was found to have no effect on three of the four tested Taxus lines. Isolated single cells were statistically similar to untreated cell cultures for peroxidase activity (model cell wall protein) and paclitaxel content (secondary metabolite produced in Taxus cell cultures). In comparison, protoplasts showed marked changes in both peroxidase activity and paclitaxel content as compared to untreated cultures. The use of flow cytometry was demonstrated with isolated cells that were found to have > 99% viability upon staining with fluorescein diacetate. The development of a method for the isolation of single plant cells will allow the study of population dynamics and culture variability on a single cell level for the development of population models of plant cell cultures and secondary metabolism. © 2004 Wiley Periodicals, Inc.
Glutamic acid removal and PHB storage in the activated sludge process under dynamic conditions
Authors: Dionisi Davide , Majone Mauro , Miccheli Alfredo , Puccetti Caterina , Sinisi Carlo 
Published: May 2004

AbstractGlutamic acid removal in the activated sludge process is studied herein, primarily the formation of storage polymers under dynamic conditions. The activated sludge process was operated by using a sequencing batch reactor (sludge age of 6 d) fed with a synthetic mixture of readily available carbon sources, including glutamic acid. Removal of glutamic acid as the only carbon sources was studied in batch tests, along with oxygen consumption, ammonia uptake – release, and formation of storage polymers. It was found that poly‐3‐hydroxybutyrate (PHB) was stored and that the storage also occurred simultaneously to biomass growth. PHB storage accounted for 16% of the overall solids that were formed from glutamic acid, as the average value of nine batch tests. Neither other Polyhydroxyalkanoates nor polyglutamic acid were detected . Nuclear magnetic resonance analysis, performed on biomass extracts, allowed us to clarify the main metabolic pathways involved in glutamic acid removal and, in particular, the pathways involved in PHB storage. It was found that glutamic acid enters the Krebs cycle as α‐ketoglutaric acid and exits to form pyruvic acid and then acetyl‐CoA, which is the starting point of PHB production pathway. © 2004 Wiley Periodicals, Inc.
Novel chemically synthesized hydroxyl‐containing jasmonates as powerful inducing signals for plant secondary metabolism
Authors: Qian Zhi‐Gang , Zhao Zhen‐Jiang , Xu Yufang , Qian Xuhong , Zhong Jian‐Jiang 
Published: May 2004

AbstractNovel hydroxyl‐containing jasmonate derivatives were chemically synthesized and evaluated by bioassay as potential elicitors for stimulating the biosynthesis of plant secondary metabolites. A suspension culture of Taxus chinensis, which produces a bioactive taxoid, taxuyunnanine C (Tc), was taken as a model plant cell system. Experiments on the timing of addition of jasmonates and dose response indicated that day 7 and 100 μM was the optimal elicitation time and concentration, respectively, for both cell growth and Tc accumulation. Tc accumulation was increased more in the presence of novel hydroxyl‐containing jasmonates compared to that with methyljasmonate (MJA) addition. For example, addition of 100 μM 2,3‐dihydroxypropyl jasmonate on day 7 led to a very high Tc content of 47.2 ± 0.5 mg/g (at day 21), whereas the Tc content was 29.2 ± 0.6 mg/g (on the same day) with addition of 100 μM MJA. Quantitative structure–activity analysis of various jasmonates suggests that the optimal lipophilicity and the number of hydroxyl groups may be two important factors affecting their elicitation activity. In addition, the jasmonate elicitors were found to induce plant defense responses, including oxidative burst and activation of L‐phenylalanine ammonia lyase (PAL). Interestingly, a higher level of H2O2 production and PAL activity was detected with elicitation by the synthesized jasmonates compared with that by MJA, which corresponded well to the superior stimulating activity in the former. This work indicates that the newly synthesized hydroxyl‐containing jasmonates can act as powerful inducing signals for secondary metabolite biosynthesis in plant cell cultures. © 2004 Wiley Periodicals, Inc.
In situ product removal using a crystallization loop in asymmetric reduction of 4‐oxoisophorone by Saccharomyces cerevisiae
Authors: Buque‐Taboada Evelyn M. , Straathof Adrie J.J. , Heijnen Joseph J. , van der Wielen Luuk A.M. 
Published: May 2004

AbstractIn situ product crystallization was investigated for solid product crystals that were obtained during fermentation. The model reaction was the asymmetric reduction of 4‐oxoisophorone (OIP) using baker's yeast (S. cerevisiae) as a biocatalyst. The target product was 6R‐dihydro‐oxoisophorone (DOIP), also known as levodione, a key intermediate in carotenoid synthesis. DOIP was degraded by baker's yeast mainly to (4S,6R)‐actinol, an unwanted byproduct in the process. Actinol formation reached up to 12.5% of the initial amount of OIP in the reactor during a batch process. However, better results were obtained when the dissolved DOIP concentration was controlled using an integrated fermentation–crystallization process because: (a) actinol formation was reduced to 4%; and (b) DOIP crystal formation in the reactor was avoided. DOIP productivity was improved by 50% and its selectivity was raised from 87% to 96% relative to the batch process. In the integrated process, most of the product was recovered as pure crystals; this may already minimize, if not eliminate, the need for organic solvents in the final purification steps. An almost sixfold reduction in biocatalyst consumption per kilogram product was achieved, which also can contribute to the minimization of waste streams. © 2004 Wiley Periodicals, Inc.
Rapid chromatography for evaluating adsorption characteristics of cellulase binding domain mimetics
Authors: Mosier Nathan S. , Wilker Jonathan J. , Ladisch Michael R. 
Published: May 2004

AbstractThe cost of cellulolytic enzymes is one barrier to the economic production of fermentable sugars from lignocellulosic biomass for the production of fuels and chemicals. One functional characteristic of cellulolytic enzymes that improves reaction kinetics over mineral acids is a cellulose binding domain that concentrates the catalytic domain to the substrate surface. We have identified maleic acid as an attractive catalytic domain with pKa and dicarboxylic acid structure properties that hydrolyze cellulose while producing minimal degradation of the glucose formed. In this study we report results of a rapid chromatographic method to assess the binding characteristics of potential cellulose binding domains for the construction of a synthetic cellulase over a wide range of temperatures (20° to 120°C). Aromatic, planar chemical structures appear to be key indicators of cellulose adsorption. Indole, the side‐chain of the amino acid tryptophan, has been shown to reversibly adsorb to cellulose at temperatures between 30° and 120°C. Trypan blue, a polyaromatic, planar molecule, was shown to be irreversibly adsorbed to cotton cellulose at temperatures of <120°C on the time scale of the experiments. These results confirm the importance of hydrophobic cellulose and the cellulose‐binding component of cellulolytic enzymes and cellulolytic enzyme mimetics. © 2004 Wiley Periodicals, Inc.
Encapsulating chondrocytes in degrading PEG hydrogels with high modulus: Engineering gel structural changes to facilitate cartilaginous tissue production
Authors: Bryant Stephanie J. , Bender Ryan J. , Durand Kevin L. , Anseth Kristi S. 
Published: May 2004

AbstractA major challenge when designing cell scaffolds for chondrocyte delivery in vivo is creating scaffolds with sufficient mechanical properties to restore initial function while simultaneously controlling temporal changes in the gel structure to facilitate tissue formation. To address this design challenge, degradable photocrosslinked hydrogels based on poly(ethylene glycol) were investigated. To alter the gel's initial mechanical properties, hydrogels were fabricated by varying the initial macromer concentration from 10% to 15% to 20%. A twofold increase in macromer concentration resulted in an eightfold increase in the initial compressive modulus from 60 to 500 kPa. Gel degradation was tailored by incorporating fast‐degrading crosslinks that enable maximal extracellular matrix (ECM) diffusion with time and a minimal number of nondegrading (or slowly degrading) crosslinks to maintain scaffold integrity and prevent complete gel erosion during tissue formation. Chondrocytes encapsulated in these gels produced cartilaginous tissue rich in glycosaminoglycans and collagen as seen biochemically and histologically. Interestingly, mass loss appeared to more closely match tissue secretion in gels fabricated from a 15% macromer concentration. However, the spatial ECM distribution was grossly similar in all three gels. By tailoring gel degradation and controlling network evolution during degradation, gels with optimal properties can be fabricated to support initially physiologic compressive loads while simultaneously supporting the formation of a neotissue. © 2004 Wiley Periodicals, Inc.