bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolic model for acetate uptake by a mixed culture of phosphate‐ and glycogen‐accumulating organisms under anaerobic conditions
Authors: Yagci Nevin , Artan Nazik , Çokgör Emine Ubay , Randall Clifford W. , Orhon Derin 
Published: September 2003

AbstractThis paper proposes a new metabolic model for acetate uptake by a mixed culture of phosphate‐ and glycogen‐accumulating organisms (PAOs and GAOs) under anaerobic conditions. The model uses variable overall stoichiometry based on the assumption that PAOs may have the ability of using the glyoxylate pathway to produce the required reducing power for polyhydroxyalkonate (PHA) synthesis. The proposed model was tested and verified by experimental results. A sequencing batch reactor system was operated for enhanced biological phosphorus removal (EBPR) with acetate as the sole carbon source at different influent acetate/phosphate ratios. The resulting experimental data supported the validity of the proposed model, indicating the presence of GAOs for all tested HAc/P ratios, especially under P‐limiting conditions. Strong agreement is observed between experimental values and model predictions for all model components, namely, PHB production, PHA composition, glycogen utilization, and P release. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 359–373, 2003.
Image analysis of light distribution in a photobioreactor
Authors: Jung Sang‐Kyu , Lee Sun Bok 
Published: September 2003

AbstractLight intensity is a crucial factor that determines the growth of photosynthetic cells. This study analyzed the light distribution in a photobioreactor by processing images, captured with a digital camera, of a rectangular photobioreactor containing Synechococcus sp. PCC6801 as a model microorganism. The gray‐scale images obtained clearly demonstrate the variation of the light‐distribution profiles upon changing cell concentrations and external light intensity. Image‐processing techniques were also used to predict the cell density in the photobioreactor. By analyzing the digitized image data with a neural network model, we were able to predict the cell concentrations in the photobioreactor with a <5% error. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 394–397, 2003.
Towards on‐line monitoring of cell growth in microporous scaffolds: Utilization and interpretation of complex permittivity measurements
Authors: Bagnaninchi Pierre‐Olivier , Dikeakos Maria , Veres Teodor , Tabrizian Maryam 
Published: September 2003

AbstractHere we demonstrate the ability to characterize microporous scaffolds and evaluate cell concentration variation via the utilization and interpretation of complex permittivity measurements (CP), a direct and nondestructive method. Polymer‐based microporous scaffolds are of importance to tissue engineering, particularly in the promotion of cell adhesion, proliferation, and differentiation in predefined shapes. Chitosan gel scaffolds were seeded with increasing concentrations of macrophages to simulate cell growth. Complex permittivity measurements were performed using a dielectric probe and a vector network analyzer over a frequency ranging from 200 MHz to 2 GHz. An effective medium theory was applied to interpret the data obtained; respectively, Looyenga and Maxwell‐Wagner‐Hanai functions were used to retrieve the porosity and the variation of the cell concentration from the CP measurements. Calculated porosities were in agreement with experimental evaluation—porosity ranged from 81–96%. Changes in cell concentration inside the scaffolds upon injection of differing cell concentrations into the scaffold were detected distinguishably. Variations resulting from the cumulative injection of 400–1800 μL of 106 cells/mL solution into the scaffold were monitored. Results suggest that CP measurements in combination with an appropriate effective medium approximation can enable on‐line monitoring of cell growth within scaffolds. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 343–350, 2003.
Co‐expression of molecular chaperones does not improve the heterologous expression of mammalian G‐protein coupled receptor expression in yeast
Authors: Butz James A. , Niebauer Ronald T. , Robinson Anne Skaja 
Published: September 2003

AbstractThe limitations to high‐level expression of integral membrane proteins are not well understood. The human A2a adenosine receptor (A2a) and mouse Substance P receptor (SPR) were individually expressed in S. cerevisiae to identify potential cellular bottlenecks for G‐protein coupled receptors. In the yeast system, A2a was not N‐linked glycosylated but was functional and plasma membrane‐localized. A2a also contained an intramolecular disulfide bond. Substance P receptor was also not N‐linked glycosylated in yeast, but, unlike A2a, SPR was intracellularly retained, nonfunctional, and did not appear to contain an intramolecular disulfide bond. Since both receptors contain N‐linked glycosylation and disulfide bonds in mammalian systems, machinery responsible for interacting with these modifications was investigated—specifically, the potential interactions between the nascent receptor and ER‐resident proteins were explored. The chaperones calnexin and protein disulfide isomerase were co‐overexpressed with the GPCRs to determine the effect on total and active yields of A2a and SPR, as well as on receptor trafficking. The effect of co‐expressing the chaperone BiP on the total yields of A2a as well as intracellular fates of both receptors were determined. The co‐expression of ER resident proteins did not improve A2a yields nor did they restore SPR activity or improve SPR cell surface expression. Taken together, these results indicate that an ER‐folding bottleneck does not limit the expression of the mammalian receptors in yeast. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 292–304, 2003.
Tracking the acetate threshold using DO‐transient control during medium and high cell density cultivation of recombinant Escherichia coli in complex media
Authors: Johnston Wayne A. , Stewart Meredith , Lee Peter , Cooney Michael J. 
Published: September 2003

AbstractDO‐transient nutrient controllers use the dissolved oxygen signal to attempt acetate threshold tracking during fed‐batch cultivation of recombinant E. coli. Here we apply DO‐transient control to the production of Jembrana disease virus protein in complex Super Luria medium and compare performance against a high‐limit pH‐stat controller. For induction at medium cell density (harvest between 31 and 32.5 g dcw L) a total productivity of 0.27 g L h was achieved as compared to 0.24 g L h with the high‐limit pH‐stat. For induction at high cell density (harvest at 60 g dcw L), decreased productivity (0.12 g L h) was attributed to the effect of acetate accumulation on recombinant protein formation and a concomitant lowering of the critical growth rate. Our results suggest that complex media provides a difficult environment for the application of acetate threshold tracking DO‐transient control because of difficulties in re‐oxidizing acetate, and apparent localized production of acetate below the production threshold (as detected by the DO‐transient controller as SPOURcrit). Configuring the DO‐transient controller to avoid aggressive threshold probing is suggested as a means to improve performance and reduce acetate accumulation in complex media. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 314–323, 2003.
Virus‐like particle production at low multiplicities of infection with the baculovirus insect cell system
Authors: Maranga Luis , Brazão Tiago F. , Carrondo Manuel J. T. 
Published: September 2003

AbstractThe baculovirus insect cell expression system (BEVS) was used for the production of self‐formingPorcine parvovirus‐like particles (VLPs) in serum‐free medium. A low multiplicity of infection (MOI) strategy was used to overcome an extra virus amplification step, undesirable in industrial production, and to minimize the virus passage effect. It was confirmed that the time of infection (TOI) and MOI are dependent variables. Higher cell densities were obtained at low MOIs, keeping a constant TOI; however, both volumetric and specific productivities were lower. In synchronous infection, at high MOI, the specific productivity decreased when the cells were infected in the late phase of growth. Product degradation due to cell lysis strongly influenced the optimal time of harvest (TOH). Time of harvest was found to be highly dependent on the MOI, and a direct relationship with the cell yield was obtained.Analysis of the culture medium reveals that glutamine depletion occurs in the late phase of the growth. Supplementation of glutamine to uninfected cell cultures resulted in an increased cell yield. Its addition to cultures infected in the middle phase of the growth curve was also able to restore the productivity levels, but addition to cells in their stationary phase caused no observable effect on product expression. The study clearly shows that for a specific TOI it is not obvious what the correct MOI should be to obtain the best volumetric productivity. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 245–253, 2003.
Large‐scale transient transfection of serum‐free suspension‐growing HEK293 EBNA1 cells: Peptone additives improve cell growth and transfection efficiency
Authors: Pham Phuong Lan , Perret Sylvie , Doan Huyen Chau , Cass Brian , St‐Laurent Gilles , Kamen Amine , Durocher Yves 
Published: September 2003

AbstractLarge‐scale transient transfection of mammalian cells is a recent and powerful technology for the fast production of milligram amounts of recombinant proteins (r‐proteins). As many r‐proteins used for therapeutic and structural studies are naturally secreted or engineered to be secreted, a cost‐effective serum‐free culture medium that allows their efficient expression and purification is required. In an attempt to design such a serum‐free medium, the effect of nine protein hydrolysates on cell proliferation, transfection efficiency, and volumetric productivity was evaluated using green fluorescent protein (GFP) and human placental secreted alkaline phosphate (SEAP) as reporter genes. The suspension growing, serum‐free adapted HEK293SF‐3F6 cell line was stably transfected with an EBNA1‐expression vector to increase protein expression when using EBV oriP bearing plasmids. Compared to our standard serum‐free medium, concomitant addition of the gelatin peptone N3 and removal of BSA slightly enhanced transfection efficiency and significantly increased volumetric productivity fourfold. Using the optimized medium formulation, transfection efficiencies between 40–60% were routinely obtained and SEAP production reached 18 mg/L−1. To date, we have successfully produced and purified over fifteen r‐proteins from 1–14‐L bioreactors using this serum‐free system. As examples, we describe the scale‐up of two secreted his‐tagged r‐proteins Tie‐2 and Neuropilin‐1 extracellular domains (ED) in bioreactors. Each protein was successfully purified to >95% purity following a single immobilized metal affinity chromatography (IMAC) step. In contrast, purification of Tie‐2 and Neuropilin‐1 produced in serum‐containing medium was much less efficient. Thus, the use of our new serum‐free EBNA1 cell line with peptone‐enriched serum‐free medium significantly improves protein expression compared to peptone‐less medium, and significantly increases their purification efficiency compared to serum‐containing medium. This eliminates labor‐intensive and expensive chromatographic steps, and allows for the simple, reliable, and extremely fast production of milligram amounts of r‐proteins within 5 days posttransfection. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 332–342, 2003.
Use of a plant‐derived enzyme template for the production of the green‐note volatile hexanal
Authors: Schade Frank , Thompson John E. , Legge Raymond L. 
Published: September 2003

AbstractHexanal is a key organoleptic element of green‐note that is found in both fragrances and flavors. We report a novel process for the production of hexanal using immobilized enzyme templates extracted from different plant sources in combination with hollow‐fiber ultrafiltration for in situ separation. Enzyme templates, known to be responsible for the synthesis of hexanal from linoleic acid (18:2), were isolated from naturally enriched tissues including carnation petals, strawberry and tomato leaves. These templates were immobilized in an alginate matrix and used as a biocatalyst in a packed‐bed bioreactor. Continuous product recovery was achieved using a hollow‐fiber ultrafiltration unit. The effects of pH, reaction temperature, and substrate and enzyme concentrations were studied and their effects on hexanal generation identified and optimized. Utilizing optimized conditions, hexanal production 112‐fold higher than endogenous steady‐state levels in a corresponding amount of plant tissue could be achieved over a 30‐minute period. Based on the reactor studies, product inhibition also appears to be an important factor for bioreactor‐based hexanal production. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 265–273, 2003.
Comparison of theoretical and experimental data to evaluate substrate diffusional limitations for crown ether‐ and methyl‐β‐cyclodextrin‐activated serine protease subtilisin Carlsberg in tetrahydrofuran
Authors: Santos Angélica M. , González Maryliz , Pacheco Yamaris , Griebenow Kai 
Published: September 2003

AbstractSimple co‐lyophilization of serine protease subtilisin Carlsberg with [12]‐crown ether‐4 (12‐crown‐4) or methyl‐β‐cyclodextrin (MβCD) drastically increases its catalytic activity in organic solvents. We investigated whether the improved activity would cause substrate diffusional limitations. To experimentally assess the issue, the enzyme was inactivated with PMSF. Different amounts of active and inactive subtilisin were codissolved in 10 mM phosphate buffer (pH 7.8) followed by lyophilization with or without 12‐crown‐4 or MβCD. Initial rates for the transesterification reaction of N‐acetyl‐L‐phenylalanine ethyl ester and 1‐propanol in anhydrous THF were plotted vs. the amount of active enzyme present in the formulations. For all three enzyme formulations a linear relationship was observed and the results clearly show that activation of subtilisin Carlsberg by crown ethers and MβCD did not cause diffusional limitations. This was somewhat surprising because theoretical models predicted such diffusional limitations for the activated formulations. However, investigation of the protein powder particles obtained after co‐lyophilization with 12‐crown‐4 and MβCD revealed a drastically reduced particle size for these formulations when suspended in THF. The particle micronization afforded by the excipients prevented substrate diffusional limitations, a factor that should be taken into account when designing improved enzyme formulations for synthetic applications in organic solvents. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 324–331, 2003.
On the dynamics of a spherical scaffold in rotating bioreactors
Authors: Ramirez L. E. S. , Lim E. A. , Coimbra C. F. M. , Kobayashi M. H. 
Published: September 2003

AbstractWe analyze the dynamics of a spherical scaffold in rotating bioreactors (or clinostats). The idealized clinostat environment consists of a purely rotational flow that is perpendicular to a gravitational field. We confirm through a detailed analytical study that lift effects considerably alter the position of the equilibrium point reached by the scaffolds in the (vertical) direction collinear to the gravitational field. This result holds for small particle and shear Reynolds numbers. Our analysis shows that the inertial lift effect is negligible in the horizontal direction. We show that for all rotations of practical interest, and for the range of particle Reynolds number smaller than unity, the vertical coordinate of the equilibrium point is strongly affected by consideration of lift effects. For light (heavy) particles, inclusion of lift in the formation forces the equilibrium position to be below (above) the horizontal plane that contains the axis of rotation. The equilibrium point for light particles is stable and therefore is observable experimentally. The equilibrium point for heavy particles is unstable. We also estimate the stress level applied to the scaffold and derive an algebraic expression that indicates that the stress level acting on the scaffold decreases with increasing shear Reynolds number. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 382–389, 2003.
Inducible expression of green fluorescent protein in porcine tracheal epithelial cells by the bovine tracheal antimicrobial peptide promoter
Authors: Dyce Paul W. , Devries Robert J. , Walton John , Hacker Roger R. , Li Julang 
Published: September 2003

AbstractTracheal antimicrobial peptides (TAP) are expressed primarily in respiratory epithelial cells of cattle. The TAP expression is inducible upon challenge with bacteria and bacterial lipopolysaccharide (LPS). In pigs, a promoter that can be activated by bacterial infection has yet to be identified. The objective of this study was to use green fluorescent protein (GFP) as a reporter gene to determine the function and inducibility of the bovine TAP promoter in porcine primary tracheal epithelial cells. Thus, evaluating the feasibility of using this promoter to direct transgene expression in porcine cells.The percentage of GFP expressing cells increased in response to LPS challenge in both a dose‐dependent and time‐dependent manner (p< 0.05). Moreover, when the intensity of the GFP fluorescence was measured, it was observed that the percentage of cells that have a high intensity of GFP fluorescence, also increased gradually as LPS dose increased, the difference between the unchallenged (control) and challenged group become statistically significant at the concentration of 100 ng/mL after 36 h LPS challenge (p< 0.05). The level of induced‐expression driven by the TAP promoter was 67.8 ±12.2% that of the cytomegalovirus (CMV) promoter. The intensity of GFP fluorescence by the TAP promoter was 39.8 ± 7.6% when compared to the expression driven by the CMV promoter. These data suggest the TAP promoter functions at a lower, but comparable, level to the strong CMV promoter.Our data demonstrated that the bovine TAP promoter was functional in porcine primary tracheal epithelial cells. The ability of the TAP promoter to control gene expression in an inducible manner in the porcine respiratory tract presents an important application potential in transgenic animal studies. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 374–381, 2003.
Parental influences and social modelling of youth lottery participation
Authors: Felsher Jennifer R. , Derevensky Jeffrey L. , Gupta Rina 
Published: September 2003

AbstractObjectiveThe present study sought to investigate the relationship between perceived parental lottery involvement and the bearing this has upon youth lottery participation.ParticipantsOne thousand seventy(two youth, 10–18 years of age participated from 20 elementary and nine high schools throughout the province of Ontario, Canada.MeasurementsMeasuring Youth Lottery Participation and Playing Behaviour Questionnaire and the DSM(IV(MR(J Revised to screen for youth pathological gambling.FindingsYouth reported playing all forms of lottery tickets with 77% reporting that their parents purchase scratch tickets, lottery draws (50%), and sports tickets (23%) for them. Parental purchases of lottery tickets for their children increased by level of gambling severity. Participants with significant gambling problems perceived higher parental participation in the lottery compared to non(gamblers and social gamblers. The majority of participants reported that their parents were aware of their lottery involvement and were not afraid of getting caught purchasing lottery tickets in spite of legal prohibitions.ConclusionThe results suggest youths' perception of parental involvement with the lottery plays an important role in the initiation and maintenance of lottery participation for youth. Given that youth report receiving lottery tickets from their parents, it is clear that the lottery is perceived as an innocuous form of gambling. Public awareness programmes and education of this issue is critical. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of gender and sexuality on judgements of victim blame and rape myth acceptance in a depicted male rape
Authors: Davies Michelle , McCartney Samantha 
Published: September 2003

AbstractRelatively few studies have investigated judgements towards male rape, and no published studies have investigated gay men's judgements towards this offence. The current study investigated the effects of gender and sexuality on victim blame and male rape myth acceptance in the depicted rape of a gay man. It was predicted that heterosexual men would make the most anti‐victim judgements, while gay men would make the most pro‐victim judgements. One hundred and fifty members of the UK population read a scenario that depicted a male rape, and then completed a questionnaire that measured blame and rape myths. As predicted, heterosexual men endorsed more rape myths and blamed the victim more than heterosexual women or gay men. Gay men made the most pro‐victim judgements overall. Results are discussed in relation to homophobia and traditional gender roles. Copyright © 2003 John Wiley & Sons, Ltd.
Narrating the negative consequences of elder care and familial obligation in Atlantic Canada
Authors: Hodgetts D. , Pullman D. , Goto A. 
Published: September 2003

AbstractAt a time when renewed emphasis is being placed on the role of the family in providing care for elderly people, shifts in family structures and the demographic profile of societies such as Atlantic Canada are impacting on community structures foundational to familial caregiving practices. Research shows that family members who attempt to provide familial care without adequate support risk negative health and interpersonal consequences. Hence many find it necessary to reflect upon their familial obligations. This article investigates the storytelling processes through which caregivers, aged between 45 and 55 years (N = 26), make sense of their efforts to provide care. We explore the ways in which participants in four focus groups and 12 interviews refer to negative consequences of caring in order to navigate dilemmas arising from their enactment of familial obligations in the absence of adequate support. Copyright © 2003 John Wiley & Sons, Ltd.
Human capital, acculturation and social identity: Bosnian refugees in Australia
Authors: Colic‐Peisker Val , Walker Iain 
Published: September 2003

AbstractThis article explores the processes of acculturation and identity among refugees from Bosnia and Herzegovina who resettled in the Australian cities of Perth and Sydney during the 1990s. We start from the idea that refugees, through the process of forced migration, lose aspects of their identities that were embedded in their former communities, jobs, skills, language, and culture. Upon arrival in a new society, they seek to reconstruct their identity, and we argue that this happens in the context of the process of acculturation. We use two social psychological perspectives, social identity theory and acculturation theory, and the sociological theory of the migration of human capital, to examine our data collected by qualitative research methods from refugees and Australian professionals who work in the government‐funded refugee resettlement programme. Our data highlight the loss of identity experienced in forced migration, difficulties in refugee acculturation and identity reconstruction, and collective and individual strategies in acculturation and identity adaptation. We see our perspective as essentially interdisciplinary, and take an interactional view of the acculturation and identity processes, as the characteristics of both the host society and the immigrants affect them. Copyright © 2003 John Wiley & Sons, Ltd.