bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevated temperature effects on the oxidant/antioxidant balance in submerged batch cultures of the filamentous fungus Aspergillus niger B1‐D
Authors: Bai Zhonghu , Harvey Linda M. , McNeil Brian 
Published: July 2003

AbstractIn the present study the relationship between oxidative stress and elevated culture temperature was examined in an industrially relevant fungal culture, Aspergillus niger B1‐D. For the first time, both the intracellular levels of the main stressor species (superoxide radical [O2.−]) and activities of cellular defensive enzymes (superoxide dismutase [SOD], catalase [CAT], and glutathione peroxide [GPx]) were quantified at varying temperature (25, 30, 35, 40°C) to more fully characterize culture response in different growth phases. Elevated culture temperature led to increased O2.− levels in various culture phases. In the exponential phase this was due to an enhanced generation of O2.−, whereas in stationary phase a decreased dismutation rate may also have contributed. CAT activities generally increased with culture temperature, whereas GPx activity changed little as temperature rose, indicating that GPx played only a minor role in destroying H2O2 in this A. niger. The combination of elevated temperature (35°C) and increased O2 supply (50% enrichment) led to decreased levels of O2.− compared to the cultivation at 35°C gassed with air, probably due to enhanced activity of the alternative fungal respiratory pathway. Our findings indicate that while elevated cultivation temperature does clearly induce oxidative stress events, mechanistically, it does so by a rather more complex route than previous studies indicate. Elevated temperature caused a marked disparity in the activities of SOD and CAT, very distinct from the integrated increase in activity of these enzymes in response to oxidative stress. © 2003 Wiley Periodicals. Biotechnol Bioeng 83: 772–779, 2003.
Clonal expansion of adult rat hepatic stem cell lines by suppression of asymmetric cell kinetics (SACK)
Authors: Lee Hsuan‐Shu , Crane Gracy G. , Merok Joshua R. , Tunstead James R. , Hatch Nicole L. , Panchalingam Krishnanchali , Powers Mark J. , Griffith Linda G. , Sherley James L. 
Published: July 2003

AbstractAdult stem cells have potential use for several biomedical applications, including cell replacement therapy, gene therapy, and tissue engineering. However, such applications have been limited due to difficulties encountered in expanding functional adult stem cells. We have developed a new approach to the problem of adult stem cell expansion based on the suppression of asymmetric cell kinetics (SACK). We postulated that asymmetric cell kinetics, required for adult stem cell function, were a major barrier to their expansion in culture. As such, conversion of adult stem cells from asymmetric cell kinetics to symmetric cell kinetics would promote their exponential expansion and longterm propagation in culture. The purine nucleoside xanthosine (Xs), which promotes guanine ribonucleotide biosynthesis, can be used to reversibly convert cells from asymmetric cell kinetics to symmetric cell kinetics. We used Xs supplementation to derive clonal epithelial cell lines from adult rat liver that have properties of adult hepatic stem cells. The properties of two Xs‐derived cell lines, Lig‐8 and Lig‐13, are described in detail and compared to properties of adult rat hepatic cell lines derived without Xs supplementation. The Xs‐derived cell lines exhibit Xs‐dependent asymmetric cell kinetics and Xs‐dependent expression of mature hepatic differentiation markers. Interestingly, Lig‐8 cells produce progeny with properties consistent with hepatocyte differentiation, while Lig‐13 progeny cells have properties consistent with bile duct epithelium differentiation. A stable adult cholangiocyte stem cell line has not been previously described. Consistent with the principles of their derivation, the SACK‐derived hepatic cell lines exhibit neither senescence nor tumorigenic properties, and their differentiation properties are stable after longterm culture. These characteristics of SACK‐derived stem cell lines underscore asymmetric cell kinetics as an essential adult stem cell property with potential to be the basis for a general approach to expansion and propagation of diverse adult stem cells. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 760–771, 2003.
Acetohydroxyacid synthase: A new enzyme for chiral synthesis of R‐phenylacetylcarbinol
Authors: Engel Stanislav , Vyazmensky Maria , Geresh Shimona , Barak Ze'ev , Chipman David M. 
Published: July 2003

AbstractWe have found that acetohydroxyacid synthase (AHAS) is an efficient catalyst for the enantiospecific (≥98% enantiomeric excess) synthesis of (R)‐phenylacetylcarbinol (R‐PAC) from pyruvate and benzaldehyde, despite the fact that its normal physiological role is synthesis of (S)‐acetohydroxyacids from pyruvate and a second ketoacid. (R)‐phenylacetylcarbinol is the precursor of important drugs having α and β adrenergic properties, such as L‐ephedrine, pseudoephedrine, and norephedrin. It is currently produced by whole‐cell fermentations, but the use of the isolated enzyme pyruvate decarboxylase (PDC) for this purpose is the subject of active research and development efforts. Some of the AHAS isozymes of Escherichia coli have important advantages compared to PDC, including negligible acetaldehyde formation and high conversion of substrates (both pyruvate and benzaldehyde) to PAC. Acetohydroxyacid synthase isozyme I is particularly efficient. The reaction is not limited to condensation of pyruvate with benzaldehyde and other aromatic aldehydes may be used. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 833–840, 2003.
Substrate inhibition kinetics for toluene and benzene degrading pure cultures and a method for collection and analysis of respirometric data for strongly inhibited cultures
Authors: Alagappan Gunaseelan , Cowan Robert 
Published: July 2003

AbstractWe present an evaluation of the qualitative and quantitative effects that high concentrations of benzene and toluene have on the growth rate of several pure cultures that use these compounds as their sole carbon and energy source. The cultures employed were five widely studied environmental isolates: Pseudomonas putida F1, P. putida mt2, P. mendocina KR, Ralstonia pickettii PKO1, and Burkholderia cepacia G4. Three cultures degraded toluene following a pattern consistent with the kinetic model of Wayman and Tseng (1976) while the other two followed a modification of this model introduced by Alagappan and Cowan (2001). The pattern followed for benzene degradation was different than that for toluene degradation for all four capable pure cultures and consistent with that described by the model of Luong (1987). Mechanisms of substrate inhibition and solvent toxicity are discussed, used to conceptually evaluate the reasons for the differences in inhibition behavior, and used to support a call for more widespread use of the empirical, terminal substrate concentration inhibition models employed here. We also present the methodology developed to overcome a limitation commonly encountered when attempting to collect oxygen uptake data for use in quantifying substrate inhibition kinetics. The experimental method was effective for use in the collection of high quality data and the substrate inhibition models most useful in representing the growth of bacteria on these solvents are those that show a complete loss of activity at high concentration rather than the more popular asymptotic inhibition models. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 798–809, 2003.
Evaluation of effective diffusion coefficient and intrinsic kinetic parameters on azo dye biodegradation using PVA‐immobilized cell beads
Authors: Chen Kuo‐Cheng , Wu Jane‐Yii , Yang Wen‐Bin , Hwang Sz‐Chwun John 
Published: July 2003

AbstractAn immobilized mixed culture (Aeromonas hydrophila, Comamonas testosteroni, and Acinetobacter baumannii) was prepared by entrapment into phosphorylated polyvinyl alcohol (PVA) gel beads. The unsteady‐state diffusion mechanism in a gel bead was applied to estimate the effective diffusion coefficients (De) and the partition coefficients (Kp) of azo dye. In addition, a simple method was developed to determine the intrinsic kinetic parameters of immobilized cells from observed reaction rates and the intrinsic kinetic parameters were then verified by fitting the experimental data into the reaction‐diffusion model in a batch reactor running at a well‐stirred state. The calculated effectiveness factor (ηcal) approached unity at Thiele modulus (Φ) < 0.3 (i.e., dp < 0.475 mm). The experimental effectiveness factor (ηexp) was in the range of 0.71–0.45 for a corresponding sphere diameter (dp) of 1.91 ± 0.16 to 4.43 ± 0.07 mm at an initial dye concentration of 200 mg/L. The results show that intraparticle diffusion resistance has a significant effect on the azo dye biodegradation rate. © 2003 Wiley Periodicals. Biotechnol Bioeng 83: 821–832, 2003.
Artificial regulatory networks and cascades for discrete multilevel transgene control in mammalian cells
Authors: Kramer Beat P. , Weber Wilfried , Fussenegger Martin 
Published: July 2003

AbstractPrototype drug‐adjustable heterologous transcription control systems designed for gene therapy applications typically show sigmoid dose–response characteristics and enable fine‐tuning of therapeutic transgenes only within a narrow inducer concentration range of a few nanograms. However, the design of clinical dosing regimes which achieve tissue‐specific concentrations with nanogram precision is yet a “mission impossible.” Therefore, most of today's transcription control systems operate as ON/OFF switches and not in a true adjustable mode. The availability of robust transcription control configurations which lock expression of a single therapeutic transgene at desired levels in response to fixed clinical doses of different inducers rather than minute concentration changes of a single inducer would be highly desirable. Based on in silico predictions, we have constructed a variety of mammalian artificial regulatory networks by interconnecting the tetracycline‐ (TETOFF), streptogramin‐ (PIPOFF), and macrolide‐ (EOFF) repressible gene regulation systems as linear (auto)regulatory cascades. These networks enable multilevel expression control of several transgenes in response to different antibiotics or allow titration of a single transgene to four discrete expression levels by clinical dosing of a single antibiotic: 1) high expression in the absence of any antibiotic (+++), 2) medium level expression following addition of tetracycline (++), 3) low level expression in response to the macrolide erythromycin (+), and 4) complete repression by streptogramins such as pristinamycin (–). The first‐generation artificial regulatory networks exemplify modular interconnections of different heterologous gene regulations systems to achieve multigene expression, fine‐tuning, or to design novel control networks with unprecedented transgene regulation properties. Such higher‐level transcription control modalities will lead the way towards composite artificial regulatory networks able to effect complex therapeutic interventions in future gene therapy and tissue engineering scenarios. © 2003 Wiley Periodicals. Biotechnol Bioeng 83: 810–820, 2003.
Comparisons of oxidative stress response genes in aerobic Escherichia coli fermentations
Authors: Lu Canghai , Bentley William E. , Rao Govind 
Published: July 2003

AbstractThe promoter regions of five SoxRS regulon genes (sodA, fumC, zwf, acnA, and acrAB) and one SoxRS regulatory protein gene (soxS) were inserted upstream of the gene of green fluorescent protein (GFP) in pGlow‐TOPO. These promoter probe plasmids were transformed into Escherichia coli Top10 resulting in six strains that produce GFP in response to superoxide‐induced stresses. Initial characterization from paraquat insults revealed significant induction of all six genes, with sodA, fumC, zwf, and soxS leading to the others in time and strength. These stress probe strains were then grown under similar conditions in fermentors and systematically exposed to varying durations of pure oxygen. Significant stimulation of the regulon was observed and quantitatively and temporally characterized by online monitoring of GFP fluorescence production (with transcriptional rate sodA > fumC > soxS, zwf > acnA, acrAB = 0). Interestingly, SoxRS regulon response occurred in typical E. coli fermentations where DO is maintained approximately 30% with increased agitation speed (with transcriptional rate acnA > sodA > zwf > acrAB > soxS, fumC = 0). These results also suggest that different molecular responses occur under different aeration schemes, all of which are intended to combat oxidative damage. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 864–870, 2003.
In silico prediction and validation of the importance of the Entner–Doudoroff pathway in poly(3‐hydroxybutyrate) production by metabolically engineered Escherichia coli
Authors: Hong Soon Ho , Park Si Jae , Moon Soo Yun , Park Jong Pil , Lee Sang Yup 
Published: July 2003

AbstractThe metabolic network of Escherichia coli was constructed and was used to simulate the distribution of metabolic fluxes in wild‐type E. coli and recombinant E. coli producing poly(3‐hydroxybutyrate) [P(3HB)]. The flux of acetyl‐CoA into the tricarboxylic acid (TCA) cycle, which competes with the P(3HB) biosynthesis pathway, decreased significantly during P(3HB) production. It was notable to find from in silico analysis that the Entner–Doudoroff (ED) pathway flux increased significantly under P(3HB)‐accumulating conditions. To prove the role of ED pathway on P(3HB) production, a mutant E. coli strain, KEDA, which is defective in the activity of 2‐keto‐3‐deoxy‐6‐phosphogluconate aldolase (Eda), was examined as a host strain for the production of P(3HB) by transforming it with pJC4, a plasmid containing the Alcaligenes latus P(3HB) biosynthesis operon. The P(3HB) content obtained with KEDA (pJC4) was lower than that obtained with its parent strain KS272 (pJC4). The reduced P(3HB) biosynthetic capacity of KEDA (pJC4) could be restored by the co‐expression of the E. coli eda gene, which proves the important role of ED pathway on P(3HB) synthesis in recombinant E. coli as predicted by metabolic flux analysis. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 854–863, 2003.
Down‐regulation of acetate pathway through antisense strategy in Escherichia coli: Improved foreign protein production
Authors: Kim Jaoon Y. H. , Cha Hyung Joon 
Published: July 2003

AbstractA problem with the use of Escherichia coli to produce foreign proteins is that although endogenously produced acetate is physiologically indispensable, it inhibits protein expression. Here we firstly employed an antisense RNA strategy as an elaborate metabolic engineering tool to partially block biosynthesis of two major acetate pathway enzymes, phosphotransacetylase (PTA) and acetate kinase (ACK). Three recombinant plasmids containing antisense genes targeting either or both of pta and ackA were constructed, and their effects on the acetate pathway and foreign protein productivity compared to control plasmid without any antisense genes were determined in E. coli BL21. Green fluorescent protein (GFP) was employed as a model foreign protein, and timing of antisense expression was controlled by using the intrinsic ackA promoter. We found that the antisense method partially reduced mRNA levels of target enzyme genes and, over time, lowered the concentration of acetate in culture media in all antisense‐regulated strains. Notably, total production of GFP was enhanced 1.6‐ to 2.1‐fold in antisense‐regulated strains, even though the degree of acetate reduction was not significantly large. It was revealed that the acetate pathway has more critical roles in cellular physiology than expected in the previous reports. When the scale of culture was increased, enhancement of protein production became larger, demonstrating that this antisense strategy can be successfully applied to practical large‐scale protein production processes. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 841–853, 2003.
Coronary stenting in patients with depressed left ventricular function: Acute and long‐term results in a selected population
Authors: Di Sciascio Germano , Patti Giuseppe , D'Ambrosio Andrea , Nusca Annunziata 
Published: July 2003

AbstractPercutaneous coronary angioplasty (PTCA) in patients with depressed left ventricular ejection fraction (LVEF) is associated with increased acute and late mortality; in contrast to plain PTCA, results of stenting in these patients have not been characterized. To assess the current outcome of stenting in patients with LV dysfunction, results from 80 patients procedures were analyzed. Intervention for acute myocardial infarction (MI) was excluded; 21% of patients had unstable angina and 30% had a recent MI. Mean LVEF was 40 ± 9% (range, 25–45%). Multivessel revascularization was done in 25 patients (31%), with a total of 114 lesions treated. Prophylactic intra‐aortic balloon pump was used in only two patients. Angiographic and clinical success was achieved in 79/80 patients (99%). There were no in‐hospital deaths, one patient (1%) had a non‐Q‐wave MI, and no patients required emergency bypass surgery (CABG). All patients completed at least 6 months follow‐up (mean, 30 ± 14 months): 64 patients (80%) remained asymptomatic, 4 (5%) had acute MI, and 5 (6%) died. In‐stent restenosis occurred in five patients (6%); of these, three required repeat PTCA, three patients (4%) underwent subsequent elective CABG. Including patients with repeat intervention, 67 patients (84%) are clinically improved; actuarial event‐free survival was 87% at 56‐month follow‐up. Thus, stenting in patients with impaired LVEF is associated with excellent outcome and lower mortality than previously reported for balloon angioplasty alone. Whether coronary stenting may be a therapeutic strategy equivalent to surgery in selected patients needs to be investigated in prospective randomized trials. Cathet Cardiovasc Intervent 2003;59:429–433. © 2003 Wiley‐Liss, Inc.
Percutaneous intervention for unprotected left main disease prior to explantation of a left ventricular assist device
Authors: Butman Samuel M. , Jamison Karen , Slepian Marvin , Edling Nancy , Arabia Francisco , Copeland Jack G. 
Published: July 2003

AbstractPercutaneous coronary intervention of unprotected left main coronary arterial disease is an alternative to surgical revascularization in selected patients. In this report, a patient with an implanted left ventricular assist device (LVAD) underwent successful coronary intervention prior to its planned removal. The implanted LVAD clearly assisted the technical performance of the intervention. Cathet Cardiovasc Intervent 2003;59:471–474. © 2003 Wiley‐Liss, Inc.
Aortic dissection after stent dilatation for coarctation of the aorta: A case report and literature review
Authors: Varma C. , Benson L.N. , Butany J. , McLaughlin Peter R. 
Published: July 2003

AbstractA case of stenting for native coarctation is described in a 65‐year‐old female with a fatal dissection after implantation. The histology of the aorta in coarctation and in the elderly is described. The experience of stenting in older patients is reviewed and discussed. Cathet Cardiovasc Intervent 2003;59:528–535. © 2003 Wiley‐Liss, Inc.
Conflicting functional assessment of stenoses in patients with previous myocardial infarction
Authors: Leesar Massoud A. , Abdul‐Baki Talal , Yalamanchili Vankata , Hakim John , Kern Morton 
Published: July 2003

AbstractThe utility of fractional flow reserve, absolute and relative flow reserve, and intravascular ultrasound may have an impact on decision‐making for percutaneous coronary intervention in patients with previous myocardial infarction and microvascular dysfunction. The role for fractional flow reserve, absolute and relative flow reserve, and intravascular ultrasound is discussed. Cathet Cardiovasc Intervent 2003;59:489–495. © 2003 Wiley‐Liss, Inc.
New technique for superior guiding catheter support during advancement of a balloon in coronary angioplasty: The anchor technique
Authors: Fujita Shinya , Tamai Hideo , Kyo Eisho , Kosuga Kunihiko , Hata Tatsuhiko , Okada Masaharu , Nakamura Takuji , Tsuji Takafumi , Takeda Shinsaku , bin Hu Fang , Masunaga Nobutoyo , Motohara Seiichiro , Uehata Hiromu 
Published: July 2003

AbstractTo get superior guiding catheter support, we tried a new method called the anchor technique. By inflating a balloon in a nontarget vessel and holding its shaft with backward force while advancing another balloon, the anchor effect for the guiding catheter could be obtained and it appeared to be helpful for a balloon or a stent to cross the target lesion. Cathet Cardiovasc Intervent 2003;59:482–488. © 2003 Wiley‐Liss, Inc.
Does gender affect the clinical outcome of patients with acute myocardial infarction complicated by cardiogenic shock who undergo percutaneous coronary intervention?
Authors: Antoniucci David , Migliorini Angela , Moschi Guia , Valenti Renato , Trapani Maurizio , Parodi Guido , Bolognese Leonardo , Santoro Giovanni M. 
Published: July 2003

AbstractThis study sought to determine the impact of female gender on clinical outcome in patients with acute myocardial infarction (AMI) complicated by cardiogenic shock (CS) due to predominant ventricular failure undergoing percutaneous coronary intervention (PCI). We analyzed gender‐related differences in procedural, angiographic, and clinical outcomes in 208 consecutive patients with AMI complicated by CS. Out of 208 patients with CS, 65 were women and 143 men. Women were older than men (74 ± 10 years vs. 66 ± 12 years; P < 0.001) and had a greater incidence of a history of hypertension (43% vs. 29%; P = 0.041). The 6‐month mortality rate was 42% in women and 31% in men (P = 0.157). There were no differences between groups in reinfarction rate and target vessel revascularization rate. Multivariate analysis showed age as the only variable independently related to the 6‐month mortality, while female gender was not related to the risk of death. The benefit of early PCI is similar in women and men, and any potential referral bias in the use of PCI based on gender differences should be avoided. Cathet Cardiovasc Intervent 2003;59:423–428. © 2003 Wiley‐Liss, Inc.
Percutaneous stenting of anastomotic stenoses in tubular interposition grafts used to repair aortic coarctation in adults
Authors: Mustapha Jihad , Sandhu Satinder K. , Khuri Bahij N. , Glancy D. Luke 
Published: July 2003

AbstractStenting is the usual treatment for recoarctation following resection with direct end‐to‐end anastomosis. We describe for the first time stenting to relieve anastomotic stenoses in tubular interposition grafts, which are used to repair approximately 10% of coarctations. Success in these two adults expands further the spectrum of large conduits that may be relieved of stenosis by stenting. Cathet Cardiovasc Intervent 2003;59:544–546. © 2003 Wiley‐Liss, Inc.