bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods
Authors: Chaubal Mahesh V. , Wang Bing , Su Geraldine , Zhao Zhong 
Published: October 2003

AbstractThe chemical composition and quantitative molar ratios among all components of biodegradable polyphosphoester copolymers of DL‐lactide and ethylphosphate were determined by a comprehensive set of NMR spectroscopic methods. The polyphosphoester copolymers studied were synthesized using condensation polymerization of oligomeric DL‐lactide prepolymers and ethyl dichlorophosphate. Conclusive identification of the chemical shift patterns of all functional groups in the copolymers required additional NMR methods such as 31P‐NMR and two‐dimensional 1H–1H COSY NMR, in addition to the synthesis and comparative NMR analysis of model compounds possessing identical phosphoester linkages in the polyphosphoester copolymers. For the polymers synthesized using the bulk polycondensation process, 1H–1H COSY NMR analysis revealed the presence of a small amount of side products that were undetected by 1H‐NMR alone. These side reactions most likely occurred between the pendant ethoxy group of the phosphoesters and the hydrogen chloride gas generated in the bulk polycondensation process. 31P‐NMR spectra of the copolymers revealed a consistent triple‐peak pattern characteristic of phosphoesters linked to a racemic mixture of D,L‐lactides. These results offered new insight into the side reactions occurring in bulk polymerization of polyphosphoesters and provided a powerful tool of characterizing complex biodegradable polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4021–4031, 2003
Mometasone furoate degradation and metabolism in human biological fluids and tissues
Authors: Teng Xiao Wei , Cutler David J. , Davies Neal M. 
Published: October 2003

AbstractThe in vitro metabolic and non‐metabolic degradation kinetics of mometasone furoate (MF) was investigated in selected human biological fluids and subcellular fractions of tissues. Qualitative and quantitative differences in transformation profiles of MF were observed among human biological media. Degradation was the major event in plasma and urine with four new degradation products identified; A: 21‐chloro‐17α‐hydroxy‐16α‐methyl‐9β,11β‐oxidopregna‐1,4‐diene‐3,20‐dione 17‐(2‐furoate), B: 9α,21β‐dichloro‐11β,21α‐dihydroxy‐16α‐methylpregna‐1,4,17,20‐tetraen‐3‐one 21‐(2‐furoate), C: 21β‐chloro‐21α‐hydroxy‐16α‐methyl‐9β,11β‐oxidopregna‐1,4,17,20‐tetraen‐3‐one 21‐(2‐furoate), and D: 21‐chloro‐17α‐hydroxy‐16α‐methyl‐9β,11β‐oxidopregna‐1,4‐diene‐3,20‐dione. A, B and C were predominant and D was minor in plasma while A and C were predominant in urine. Hydrolysis of the 17‐ester bond of MF was not a major event in plasma. The turnover of MF in plasma was faster than that in phosphate buffers of pH 7.4.Metabolism of MF occurred primarily and rapidly in liver, appreciably in intestine, but negligibly in in vitro lung tissue. While 6β‐hydroxylation was a major metabolic pathway for MF in microsomes of both human liver and intestine, other parallel and subsequent metabolism pathways could also be involved. If these degradation and metabolic products are also formed and active in humans in vivo, both MF and its ‘active’ products need to be taken into account when determining the systemic bioavailability of MF and in establishing concentration‐effect relationships with this drug. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacokinetic characterization of a human immunodeficiency virus protease inhibitor, saquinavir, during ethanol intake in rats
Authors: Shibata Nobuhito , Kageyama Michiharu , Kishida Tomoyuki , Kimura Keisuke , Yoshikawa Yukako , Kuwahara Takeshi , Toh Jyunichiro , Shirasaka Takuma , Takada Kanji 
Published: October 2003

AbstractThroughout therapeutic drug monitoring of human immunodeficiency virus (HIV) protease inhibitors in HIV‐infected patients, it was found that plasma concentrations of saquinavir (SQV) were reduced in patients who had a habit of alcohol intake during double protease therapy with SQV and ritonavir (RTV). This study confirmed the pharmacokinetic profiles of SQV during ethanol intake in rats. After oral administration of SQV alone (20 mg/kg) in rats prepared by free access to 15% ethanol solution for 14 days (day 14 rats), the area under the concentration vs time curves (AUC) showed a significant decrease (p<0.01) in comparison with control rats from 0.78±0.10 to 0.38±0.03 μg h/ml. For intravenous administration of SQV alone (5 mg/kg) to day 14 rats, the total body clearance increased significantly by 1.4‐fold (p<0.05), whereas for intracolonic administration of SQV alone, no significant differences in the values of pharmacokinetic parameters were found between control and day 14 rats. With RTV, which has the strongest inhibitory effect on the CYP3A enzyme of the current HIV protease inhibitors, the AUC values of SQV at RTV doses of 2 and 20 mg/kg in day 14 rats also decreased significantly (p<0.01) from 1.30±0.06 to 0.57±0.05 μg h/ml and from 17.63±1.66 to 4.18±0.94 μg h/ml, respectively, indicating that the degree of the decrease of AUC values after oral administration with RTV after ethanol intake was larger than the mono‐therapy with SQV. This study showed that ethanol‐intake decreases the bioavailability of SQV after oral administration alone or with RTV. These observations provide useful information for the treatment of HIV‐infected patients when they receive a combination therapy with SQV and RTV, and arouse attention for the effects of alcohol intake. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacokinetics and tissue distribution of uraemic indoxyl sulphate in rats
Authors: Deguchi Tsuneo , Nakamura Mikio , Tsutsumi Yasuhiro , Suenaga Ayaka , Otagiri Masaki 
Published: October 2003

AbstractThe purpose of the present study was to examine the pharmacokinetic properties of indoxyl sulphate, a harmful uraemic toxin that accumulates during chronic renal failure. The pharmacokinetics and tissue distribution of indoxyl sulphate were examined in normal and 5/6 nephrectomized (CRF) rats. The uptake process of indoxyl sulphate by rat renal cortical slices in vitro was also investigated. Endogenous indoxyl sulphate was found to be mainly distributed in the kidney. The rate of elimination of indoxyl sulphate from plasma was lower in CRF rats compared with sham‐operated rats. The majority of intact indoxyl sulphate was excreted in the urine. In renal cortical slice experiments, uptake of indoxyl sulphate was a saturable process with a Km of 43.0 μm. Furthermore, sulphate conjugates, such as oestrone sulphate and dehydroepiandrosterone sulphate, inhibited the uptake of indoxyl sulphate to a greater extent than PAH. Thus, indoxyl sulphate is primarily eliminated from the plasma via the kidney by active tubular secretion, and renal uptake of indoxyl sulphate appears to be mediated by an organic anion transport system with a high affinity for oestrone sulphate and dehydroepiandrosterone sulphate. Copyright © 2003 John Wiley & Sons, Ltd.
Acetyl‐L‐carnitine permeability across the blood–brain barrier and involvement of carnitine transporter OCTN2
Authors: Inano Akihiro , Sai Yoshimichi , Nikaido Hiroko , Hasimoto Noriyoshi , Asano Masahide , Tsuji Akira , Tamai Ikumi 
Published: October 2003

AbstractOCTN2 (SLC22A5), an organic cation/carnitine transporter, is widely distributed throughout the body, including the brain. In the present study, the involvement of OCTN2 in acetyl‐L‐carnitine (ALCAR) permeation across the blood–brain barrier (BBB) was examined using a microdialysis method in mouse. OCTN2 function was examined by comparison of wild‐type mice with jvs mice, which express defective OCTN2 and are considered a model for primary systemic carnitine deficiency. Zero‐net‐flux method analysis indicated higher in vivo recovery of ALCAR and lower physiological ALCAR concentration in thalamus extracellular fluid (ECF) in jvs mice compared with wild‐type mice. Externally added ALCAR showed significantly slower initial uptake across the BBB in jvs mouse. These results indicated that OCTN2 is functionally involved in ALCAR transfer across the BBB. Total radioactivity in ECF after i.v. administration of radiolabelled ALCAR remained constant for the rest of the experimental period. Accordingly, our results indicate that ALCAR is transported from blood to brain ECF by OCTN2 at least in part, and its concentration in brain ECF is regulated by other events such as protein binding and anabolic reactions in the brain, as well as by transport across the BBB. Copyright © 2003 John Wiley & Sons, Ltd.
Non‐thermal bacterial inactivation with dense CO2
Authors: Spilimbergo S. , Bertucco A. 
Published: October 2003

AbstractThe use of CO2 under pressure (dense CO2) is one of the most promising techniques to achieve cold pasteurization and/or sterilization of liquid and solid materials, and is likely to replace or partially substitute currently and widely applied thermal processes. Although the ability of CO2 to inactivate microorganisms has been known since the 1950's, only within the last 15 years it has received special attention, and the scientific and economic interest towards practical applications is presently growing more and more. Here we collect and discuss the relevant current knowledge about the potentials of dense CO2 as a non‐thermal technology in the field of microbial inactivation. We summarize the state of the art, including definitions, description of the equipment, relevant applications, in both simple suspensions and complex media, for the treatment of a wide range of microorganisms in both liquid and solid substrates. Finally, we also summarize and discuss the different hypotheses about the mechanisms of inactivation © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 627–638, 2003.
Continuous fermentative hydrogen production from a wheat starch co‐product by mixed microflora
Authors: Hussy I. , Hawkes F.R. , Dinsdale R. , Hawkes D.L. 
Published: October 2003

AbstractFor the transition to the hydrogen economy, hydrogen must be produced sustainably, e.g., by the fermentation of agricultural material. Continuous fermentative production of hydrogen from an insoluble substrate in nonsterile conditions is yet to be reported. In this study hydrogen production using mixed microflora from heat‐treated digested sewage sludge in nonsterile conditions from a particulate co‐product of the wheat flour industry (7.5 g L−1 total hexose) at 18‐ and 12‐hour hydraulic retention times, pH 4.5 and 5.2, 30°C and 35°C was examined. In continuous operation, hydrogen yields of approximately 1.3 moles hydrogen/mole hexose consumed were obtained, but decreased if acetate or propionate levels rose, indicating metabolism shifted towards hydrogen consumption by homoacetogenesis or propionate producers. These shifts occurred both at pH 4.5 and 5.2. Sparging the reactor with nitrogen to reduce hydrogen in the off‐gas from 50% to 7% gave stable operation with a hydrogen yield of 1.9 moles hydrogen /mole hexose consumed over an 18‐day period. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 619–626, 2003.
Starch fermentation by recombinant saccharomyces cerevisiae strains expressing the α‐amylase and glucoamylase genes from lipomyces kononenkoae and saccharomycopsis fibuligera
Authors: Eksteen J.M. , van Rensburg P. , Cordero Otero R.R. , Pretorius I.S. 
Published: October 2003

AbstractLipomyces kononenkoae and Saccharomycopsis fibuligera possess highly efficient α‐amylase and/or glucoamylase activities that enable both of these yeasts to utilize raw starch as a carbon source. Eight constructs containing the L. kononenkoae α‐amylase genes (LKA1 and LKA2), and the S. fibuligera α‐amylase (SFA1) and glucoamylase (SFG1) genes were prepared. The first set of constructs comprised four single gene cassettes each containing one of the individual amylase coding sequences (LKA1, LKA2, SFA1 or SFG1) under the control of the phosphoglycerate kinase gene (PGK1) promoter and terminator, while the second set comprised two single cassettes containing SFA1 and SFG1 linked to their respective native promoters and terminators. The third set of constructs consisted of two double‐gene cassettes, one containing LKA1 plus LKA2 under the control of the PGK1 promoter and terminator, and the other SFA1 plus SFG1 controlled by their respective native promoters and terminators. These constructs were transformed into a laboratory strain Saccharomyces cerevisiae (Σ1278b). Southern‐blot analysis confirmed the stable integration of the different gene constructs into the S. cerevisiae genome and plate assays revealed amylolytic activity. The strain expressing LKA1 and LKA2 resulted in the highest levels of α‐amylase activity in liquid media. This strain was also the most efficient at starch utilization in batch fermentations, utilizing 80% of the available starch and producing 0.61g/100 mL of ethanol after 6 days of fermentation. The strain expressing SFG1 under the control of the PGK1 expression cassette gave the highest levels of glucoamylase activity. It was shown that the co‐expression of these heterologous α‐amylase and glucoamylase genes enhance starch degradation additively in S. cerevisiae. This study has resulted in progress towards laying the foundation for the possible development of efficient starch‐degrading S. cerevisiae strains that could eventually be used in consolidated bioprocessing, and in the brewing, whisky, and biofuel industries. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 639–646, 2003.
Optknock: A bilevel programming framework for identifying gene knockout strategies for microbial strain optimization
Authors: Burgard Anthony P. , Pharkya Priti , Maranas Costas D. 
Published: October 2003

AbstractThe advent of genome‐scale models of metabolism has laid the foundation for the development of computational procedures for suggesting genetic manipulations that lead to overproduction. In this work, the computational OptKnock framework is introduced for suggesting gene deletion strategies leading to the overproduction of chemicals or biochemicals in E. coli. This is accomplished by ensuring that a drain towards growth resources (i.e., carbon, redox potential, and energy) must be accompanied, due to stoichiometry, by the production of a desired product. Computational results for gene deletions for succinate, lactate, and 1,3‐propanediol (PDO) production are in good agreement with mutant strains published in the literature. While some of the suggested deletion strategies are straightforward and involve eliminating competing reaction pathways, many others suggest complex and nonintuitive mechanisms of compensating for the removed functionalities. Finally, the OptKnock procedure, by coupling biomass formation with chemical production, hints at a growth selection/adaptation system for indirectly evolving overproducing mutants. © 2003 Wiley Periodicals. Biotechnol Bioeng 84: 647–657, 2003.
Expression of vitreoscilla hemoglobin improves growth and levels of extracellular enzyme in yarrowia lipolytica
Authors: Bhave Sanjay L. , Chattoo Bharat B. 
Published: October 2003

AbstractEnhancement in oxygen uptake by high‐cell‐density cultivations has been achieved previously by expression of the bacterial hemoglobin gene from Vitreoscilla. The Vitreoscilla hemoglobin (VHb) gene was expressed in the yeast Yarrowia lipolytica to study the effect of expression in this commercially important yeast. The expression of VHb in this yeast was found to enhance growth, contrary to reported observations in wild‐type Saccharomyces cerevisiae in which there was no significant growth enhancement. VHb‐expressing Y. lipolytica exhibited higher specific growth rate, enhanced oxygen uptake rate, and higher respiratory activity. We report the beneficial effects of VHb expression on growth under microaerobic as well as under nonlimiting dissolved oxygen conditions. Earlier studies in Y. lipolytica have demonstrated inhibition of mycelia formation by respiratory inhibitors and poor nitrogen source, conditions poor for growth. VHb+ Y. lipolytica cells were more efficient at forming mycelia, indicating better utilization of available oxygen as compared with the VHb− cells. Expression of VHb was also found to increase the levels of enzyme ribonuclease secreted into the medium, a property that may be beneficial for producing heterologous proteins in Y. lipolytica. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 658–666, 2003.
Link between primary and secondary metabolism in the biotransformation of trimethylammonium compounds by escherichia coli
Authors: Cánovas M. , Bernal V. , Torroglosa T. , Ramirez J. L. , Iborra J. L. 
Published: October 2003

AbstractThe aim of this work was to understand the steps controlling the process of biotransformation of trimethylamonium compounds into L(−)‐carnitine by Escherichia coli and the link between the central carbon or primary and the secondary metabolism expressed. Thus, the enzyme activities involved in the biotransformation process of crotonobetaine into L(−)‐carnitine (crotonobetaine hydration reaction and crotonobetaine reduction reaction), in the synthesis of acetyl‐CoA (pyruvate dehydrogenase, acetyl‐CoA synthetase, and ATP:acetate phosphotransferase) and in the distribution of metabolites for the tricarboxylic acid (isocitrate dehydrogenase) and glyoxylate (isocitrate lyase) cycles, were followed in batch with both growing and resting cells and during continuous cell growth in stirred‐tank and high‐cell‐density membrane reactors. In addition, the levels of carnitine, crotonobetaine, γ‐butyrobetaine, ATP, NADH/NAD+, and acetyl‐CoA/CoA ratios were measured to determine how metabolic fluxes were distributed in the catabolic system. The results provide the first experimental evidence demonstrating the important role of the glyoxylate shunt during biotransformation of resting cells and the need for high levels of ATP to maintain metabolite transport and biotransformation (2.1 to 16.0 mmol L cellular/mmol ATP L reactor h). Moreover, the results obtained for the pool of acetyl‐CoA/CoA indicate that it also correlated with the biotransformation process. The main metabolic pathway operating during cell growth in the high cell‐density membrane reactor was that related to isocitrate dehydrogenase (during start‐up) and isocitrate lyase (during steady‐state operation), together with phosphotransacetylase and acetyl‐CoA synthetase. More importantly, the link between central carbon and L(−)‐carnitine metabolism at the level of the ATP pool was also confirmed. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 686‐699, 2003.
Data reconciliation and parameter estimation in flux‐balance analysis
Authors: Raghunathan Arvind U. , Pérez‐Correa J. Ricardo , Bieger Lorenz T. 
Published: October 2003

AbstractFlux blance analysis (FBA) has been shown to be a very effective tool to interpret and predict the metabolism of various microorganisms when the set of available measurements is not sufficient to determine the fluxes within the cell. In this methodology, an underdetermined stoichiometric model is solved using a linear programming (LP) approach. The predictions of FBA models can be improved if noisy measurements are checked for consistency, and these in turn are used to estimate model parameters. In this work, a formal methodology for data reconciliation and parameter estimation with underdetermined stoichiometric models is developed and assessed. The procedure is formulated as a nonlinear optimization problem, where the LP is transformed into a set of nonlinear constraints. However, some of these constraints violate standard regularity conditions, making the direct numerical solution very difficult. Hence, a barrier formulation is used to represent these constraints, and an iterative procedure is defined that allows solving the problem to the desired degree of convergence. This methodology is assessed using a stoichiometric yeast model. The procedure is used for data reconciliation where more reliable estimations of noisy measurements are computed. On the other hand, assuming unknown biomass composition, the procedure is applied for simultaneous data reconciliation and biomass composition estimation. In both cases it is verified that the f measurements required to get unbiased and reliable estimations is reduced if the LP approach is included as additional conatraints in the optimization. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 700–709, 2003.
Application of multivirus spike approach for viral clearance evaluation
Authors: Valera Christine R. , Chen Janice W. , Xu Yuan 
Published: October 2003

AbstractViral contamination is a common risk to continuous cell line‐derived biologics. Viral validation is thus required for license applications. Viral validation for chromatography procedures is routinely performed by spiking a model virus into the load material and performing the chromatography procedures at small scale under conditions equivalent to the commercial scale. With traditional cell‐based infectivity assays, one can only spike one model virus at one time. Quantitative PCR methods (TaqMan) make it possible to spike multiple model viruses for a chromatography procedure simultaneously. TaqMan assays can quantify multiple types of viruses and other types of nucleic acid in a single sample without cross interference because of its extremely high specificity. Therefore, a multivirus spike approach was evaluated and compared to a single virus spike approach. The study was further extended to the evaluation of host cell DNA clearance. The data shows highly comparable viral and host cell DNA clearance between the single and multiple virus spike approaches. Application of a multivirus spike approach provides significant time, manpower, and cost savings for new drug development. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 714–722, 2003.
Value of endoscopic ultrasonography as a predictor of long-term survival in oesophageal carcinoma
Authors: Mariette C , Balon J M , Maunoury V , Taillier G , Van Seuningen I , Triboulet J P 
Published: October 2003

Abstract

Background
Endoscopic ultrasonography (EUS) is considered to be the best locoregional staging technique for cancer of the oesophagus. This study evaluated the relationship between preoperative EUS findings, completeness of surgical resection and survival.

Methods
Between January 1995 and July 2002, 150 patients who underwent EUS for staging of tumours of the oesophagus were analysed prospectively. All underwent surgical resection with curative intent without neoadjuvant treatment.

Results
Patient survival was significantly related to tumour (EUS T), node (EUS N) and Union Internacional Contra la Cancrum classification (EUS UICC) stage according to sonographic findings (P = 0·003, P = 0·009 and P = 0·004 respectively), and the presence of stenosis determined by EUS (P = 0·004). EUS T stage was a prognostic factor for survival (relative risk 1·7 (95 per cent confidence interval (c.i.) 1·1 to 3·0); P = 0·046). Complete surgical resection (R0) was also significantly related to EUS T, N and UICC classification (P &lt; 0·001). EUS UICC stage was a factor predictive of R0 resection (relative risk 2·6 (95 per cent c.i. 1·4 to 4·8); P = 0·003).

Conclusion
R0 resection and survival of patients with tumours of the oesophagus were strongly related to endosonographic findings. These results support the proposal that EUS should be performed in all patients with oesophageal cancer, not only for staging patients before therapy but also to determine prognosis.