bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel hollow‐fiber anion‐exchange hybrid membranes: Preparation and characterization
Authors: Xu Tongwen , Lu Fangfang , Wu Yonghui 
Published: December 2008

AbstractTo develop ion‐exchange membranes for application in severe conditions, such as those with high temperatures, strongly oxidizing environments, or organic solvents, new hollow‐fiber anion‐exchange hybrid membranes were prepared by the immersion of brominated poly(2,6‐dimethyl‐1,4‐phenylene oxide) base hollow fibers in a tetraethoxysilane–ethanol solution followed by sol–gel and quaternary amination. Compared to conventional polymeric charged membranes, the prepared hybrid membranes were higher in both thermal and dimensional stabilities. The results suggest that tetraethoxysilane concentration was an important factor affecting the membrane's intrinsic properties. When the tetraethoxysilane concentration was in the range 15–45%, the final hollow‐fiber anion‐exchange hybrid membranes had an ion‐exchange capacity of 1.9–2.0 mmol/g, a water uptake of.83–1.23 g of water/g of dry weight, and a dimensional change ratio of 13–18%. An evaluation on the membranes' separation performances is underway. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Yield and physicochemical properties of EPS from Halomonas sp. strain TG39 identifies a role for protein and anionic residues (sulfate and phosphate) in emulsification of n‐hexadecane
Authors: Gutierrez Tony , Morris Gordon , Green David H. 
Published: December 2008

AbstractIn this study, we investigated the yield and physicochemical properties of the high molecular weight extracellular polymeric substance (HMW–EPS) produced by Halomonas sp. strain TG39 when grown on different types and ratios of substrates. Glucose (1% w/v) and a peptone/yeast extract ratio of 5.1 (0.6% w/v final concentration) yielded an EPS fraction (HMW‐glucose) exhibiting the highest anionic activity (20.5) and specific emulsifying activity (EI24 = 100%) compared to EPS produced by cells grown on mannitol, sucrose, malt extract or no carbon source. The HMW–EPS fractions were capable of binding ≈255–464 mg of methylene blue (MB) per gram of EPS, which represents the highest reported binding of MB by a bacterial EPS. A comparative evaluation of these properties to those of commercial hydrocolloids indicated that the combined effect of protein and anionic residues of the HMW–EPS contributed to its ability to emulsify n‐hexadecane. Liquid chromatography revealed the HMW‐glucose EPS to be a heterogeneous polymer with a polydispersity index of 1.8. This work presents evidence of a correlation between the anionic nature and protein content of bacterial EPS with its emulsifying qualities, and identifies EPS produced by strain TG39 as a high MB‐binding bacterial sorbant with potential biotechnological application. Biotechnol. Bioeng. 2009;103: 207–216. © 2008 Wiley Periodicals, Inc.
A novel system for evaluation of drug mixtures for potential efficacy in treating multidrug resistant cancers
Authors: Tatosian Daniel A. , Shuler Michael L. 
Published: December 2008

AbstractMultidrug resistant (MDR) cancer is difficult to treat. Chemicals that are effective MDR modulators have never exited clinical trials as FDA approved products due to side effects. It has been hypothesized that using a combination of chemotherapeutics with a mixture of MDR modulators (each with different side effects) may lead to useful treatment strategies. Because the experimental space for combination treatments can be large, this space may be impracticable to explore using animal studies. Here we describe an in vitro system based on microfabrication and cell culture that can potentially be used to explore large experimental spaces efficiently. The Microscale Cell Culture Analog (µCCA) concept mimics the body's response using interconnected compartments that represent various tissues or organs. A µCCA is based on the structure of an appropriate physiologically based pharmacokinetic (PBPK) model and emulates the body's dynamic response to exposure to various drugs and chemicals. For this problem we have chosen a µCCA with living cells representing the liver (HepG2/C3A), bone marrow (MEG‐01), uterine cancer (MES‐SA), and a MDR variant of uterine cancer (MES‐SA/DX‐5). In proof of concept experiments we found in 24 h “acute” exposures and 72 h treatments that the µCCA system predicts combining the chemotherapeutic, doxorubicin, with cyclosporine and nicardipine, as MDR modulators will have greater efficacy than using doxorubicin by itself or with either modulator alone. This combined strategy is selective in inhibiting MES‐SA/DX‐5 cell proliferation and may prove to be advantageous in vivo by specifically targeting MDR cancer with acceptable side‐effects. This cell specific synergy was not observed in traditional 96‐well plate assays. By combining the µCCA with a PBPK model, appropriate drug doses and area under the curve exposure for in vivo trials can be extrapolated directly from the results obtained with this device. This device and approach should be useful in screening potential drug/modulator combinations to determine candidate treatments for MDR cancer. Indeed this approach may be useful for in vitro evaluation of human response to a wide range of exposures to mixtures of chemicals or drugs. Biotechnol. Bioeng. 2009;103: 187–198. © 2008 Wiley Periodicals, Inc.
Monitoring of biomass composition from microbiological sources by means of FT‐IR spectroscopy
Authors: Pistorius Arthur M.A. , DeGrip Willem J. , Egorova‐Zachernyuk Tatjana A. 
Published: December 2008

AbstractAn FT‐IR spectroscopic method was developed for the simultaneous quantitative analysis of biomacromolecular components in biomass, originating from various microbiological sources. For the determination of protein, lipid and carbohydrate content, creatine phosphokinase, egg phosphatidyl choline and starch hydrolysate were chosen as external standards. This selection was based on spectral similarity and ease of availability. Protein content was based on the area under the amide II band profile around 1,545 cm−1. Because of the heterogeneous lipid composition in the different species, lipid content was determined using integration over the CH stretching vibrational population between 2,984 and 2,780 cm−1. Carbohydrate content was determined using integration over a CO and COC stretching band area between 1,180 and 1,133 cm−1. Linear regression analysis provided three calibration lines, according to which biomasses from ten species were analyzed. This approach showed good intra‐batch reproducibility. With this method we could demonstrate good reproducibility between batches of the same species with similar growth conditions while large differences in biomass composition were observed between the various species. Protein content as determined by FT‐IR spectroscopy compared well with the results obtained from elemental analysis. Biotechnol. Bioeng. 2009;103: 123–129. © 2008 Wiley Periodicals, Inc.
Automation of the acclimation phase in a sequencing batch reactor using dissolved oxygen regulation
Authors: Vargas Alejandro , Buitrón Germán 
Published: December 2008

AbstractIn this work, an automatic strategy for acclimation of biomass to toxic wastewater biodegradation in a sequencing batch reactor (SBR) is proposed and evaluated. It is based on monitoring the airflow needs for regulating the dissolved oxygen concentration at a desired set point. The regulation is achieved by using a PID controller with an input/output linearizing feedforward part, using the airflow rate as input variable. A simple algorithm to detect the end of the reaction phase using this manipulated signal is proposed. The strategy was tested on a laboratory bioreactor using 4‐chlorophenol as model toxic compound and two inocula from different sources. The results show that it is a viable alternative for automatic acclimation of biomass for toxic wastewater treatment in a SBR. Furthermore, the strategy is also suitable for the operation of the reactor after acclimation.
A methodology for the comparative evaluation of alternative bioseparation technologies
Authors: Tran Richard , Zhou Yuhong , Lacki Karol M. , Titchener‐Hooker Nigel J. 
Published: December 2008

AbstractAdvances in upstream technologies and growing commercial demand have led to cell culture processes of ever larger volumes and expressing at higher product titers. This has increased the burden on downstream processing. Concerns regarding the capacity limitations of packed‐bed chromatography have led process engineers to begin investigating new bioseparation techniques that may be considered as “alternatives” to chromatography, and which could potentially offer higher processing capacities but at a lower cost. With the wide range of alternatives, which are currently available, each with their own strengths and inherent limitations, coupled with the time pressures associated with process development, the challenge for process engineers is to determine which technologies are most worth investigating. This article presents a methodology based on a multiattribute decision making (MADM) analysis approach, utilizing both quantitative and qualitative data, which can be used to determine the “industrial attractiveness” of bioseparation technologies, accounting for trade‐offs between their strengths and weaknesses. By including packed‐bed chromatography in the analysis as a reference point, it was possible to determine the alternatives, which show the most promise for use in large‐scale manufacturing processes. The results of this analysis show that although the majority of alternative techniques offer certain advantages over conventional packed‐bed chromatography, their attractiveness overall means that currently none of these technologies may be considered as viable alternatives to chromatography. The methodology introduced in this study may be used to gain significant quantitative insight as to the key areas in which improvements are required for each technique, and thus may be used as a tool to aid in further technological development.
External modulation of HT‐1080 human fibrosarcoma cells improves urokinase production
Authors: Khaparde Shilpa S. , Roychoudhury Pradip K. , Gomes James , Mukhopadhyay Asok 
Published: December 2008

AbstractUrokinase was produced in a hollow fiber reactor using HT‐1080 human fibrosarcoma cells. External modulation comprised replenishing of the medium in the extracapillary space, reducing the serum concentration in the extracapillary space from 10% to 2% and increasing flow rate of the circulating medium in the intracapillary space from 20 to 80 mL/min, each according to a specific protocol. More than sixfold increase was observed in the cumulative urokinase production for two and three medium replenishing modulations of the extracapillary space. After 15 days of continuous operation, the highest cumulative urokinase obtained was 1.63 × 106 PU/mL. SDS‐PAGE and zymogram study established that the urokinase obtained was in the high molecular weight range of 54 kDa. The effect of external modulation on cumulative urokinase production was visualized as trajectories with respect to the ratio of lactic acid production rate (LPR) to the glucose uptake rate (GUR). The collective external modulation data showed two separate physiological regions in the cumulative urokinase vs. LPR/GUR plane. The HT‐1080 cells exhibited two distinct morphologies in these regions that may be related to acidosis and metastasis. These regions also correspond to low and high urokinase productivity.
Novel methods for storage stability and release of Bacillus spores
Authors: Sorokulova Iryna B. , Krumnow April A. , Pathirana Suram , Mandell Arnold J. , Vodyanoy Vitaly 
Published: December 2008

AbstractBacillus subtilis spores were immobilized in activated charcoal and tapioca and filled with acacia gum. These formulations were tested for spore stability during storage at temperatures ranging from 40°C to 90°C and for bacterial release. Thermodynamic analysis showed that immobilization of spores in acacia gum significantly increased their viability compared with unprotected spores. The viability was further increased when suspensions of spores in acacia gum were added to granules of charcoal and tapioca. The number of the spores released after storage was also increased when spores were treated with acacia gum prior to immobilization in tapioca and charcoal. Formulations of Bacillus spores with acacia gum and porous carriers (charcoal and tapioca) prolong the anticipated shelf‐life of spores even under ambient temperature and provide slow and steady bacterial release consistent with their high viability.
In situ extraction of polar product of whole cell microbial transformation with polyethylene glycol‐induced cloud point system
Authors: Wang Zhilong , Xu Jian‐He , Zhang Wenzhi , Zhuang Baohua , Qi Hanshi 
Published: December 2008

AbstractA novel polyethylene glycol‐induced cloud point system (PEG‐CPS) was developed for in situ extraction of moderate polar product by setting a microbial transformation of benzaldehyde into L‐phenylacetylcarbinol (L‐PAC) with Saccharomyces cerevisiae (baker's yeast) as a model reaction. The biocompatibility of the microorganism in PEG‐CPS was comparatively studied with a series of water‐organic solvent two‐phase partitioning systems. The tolerance of microorganism to the toxic substrate benzaldehyde was increased and the moderate polar product L‐PAC was extracted into the surfactant‐rich phase in the PEG‐CPS. The novel PEG‐CPS fills the gap of in situ extraction of polar product in microbial transformation left by water‐organic solvent two‐phase partitioning system. At the same time, the application of PEG‐CPS in a microbial transformation also avoids expensive solvent when compared with that of aqueous two‐phase system or CPS.
Recovery of proteins from corn and soybean extracts by membrane adsorption
Authors: Menkhaus Todd J. , Roseland Jane 
Published: December 2008

AbstractEfficient separation strategies for the recovery of high‐value proteins (native or recombinant) from plant agriculture are an important aspect of many different processes, from biopharmaceuticals to byproduct recovery during biofuel production. Here we report the use of membrane adsorption for the recovery of proteins from soybean and corn extracts, and compare the results with packed bed adsorption. Two alternative operating modes were investigated, a flowthrough strategy and a bind and elute method. Overall, membrane adsorption provided faster throughput, and had equal or slightly higher dynamic binding capacities compared with resin beads, without compromising yield and purity of the chosen target. Soybean was found to be an ideal plant host when capturing native protein on an anion exchange medium. This provided an opportunity to capture a large percentage (>80%) of native protein as the product, and/or allowed for elevated enrichment factors (>20) during purification of a recombinant target with pI > 7.0, using a flowthrough approach. On the other hand, for corn, a single ion‐exchange step was not able to capture more than 60% of the native protein. However, the bind and elute method with corn as the host for a recombinant product allowed for higher enrichment factors compared to soybean. In all cases, the concentration of a recombinant protein (as dictated by expression level) was found to play a significant role in the level of dynamic binding capacity, with higher concentration leading to elevated capacity. Likewise, a higher concentration of competing proteins was shown to decrease the overall capacity of a recombinant target.
pH‐insensitive glucose indicators
Authors: Garrett Jared R. , Wu Xinxin , Jin Sha , Ye Kaiming 
Published: December 2008

AbstractThere is an urgent need for developing a biosensor that can real‐time and noninvasively determine glucose concentration within living cells. In our previous study, we have engineered a glucose indicator protein (GIP) that can provide continuous glucose monitoring through a conformation change‐induced Förster resonance‐energy transfer measurement. Because of the pH‐sensitivity of the fluorescent proteins used in the GIP construction, the GIP made from these fluorescent proteins is less tolerant to a pH change, especially to the acidic environment. It has been well documented that intracellular pH does not always remain the same, and it fluctuates in metabolism and other cellular activities and also differs between cellular compartments. To address these issues, we developed a GIP that can tolerate to pH change. This GIP was constructed by flanking a glucose binding protein with a cyan fluorescent protein and a pH‐insensitive yellow fluorescent protein. Our experimental results indicated that the new GIP is more tolerant to pH change. The glucose response of this new GIP kept almost unchanged from pH 7.3 to 5.3, suggesting its capability of tolerating to acidic environment. This capability is desirable for intracellular glucose measurement.
Developing an industrial artemisinic acid fermentation process to support the cost‐effective production of antimalarial artemisinin‐based combination therapies
Authors: Lenihan Jacob R. , Tsuruta Hiroko , Diola Don , Renninger Neil S. , Regentin Rika 
Published: December 2008

AbstractArtemisinin‐based combination therapies (ACTs) are currently unaffordable for many of the people who need them most. A major cost component of ACTs is the plant‐derived artemisinin. A fermentation process for a precursor to artemisinin might provide a viable second source to stabilize the artemisinin supply and therefore reduce price. The heterologous production of artemisinic acid, an artemisinin precursor, by Saccharomyces cerevisiae was improved 25‐fold from a 100 mg/L flask process to a 2.5 g/L process in bioreactors. A defined medium fed‐batch process with galactose as the carbon source and inducer was developed, with titers of 1.3 g/L. In this strain ERG9 was controlled with promoter Pmet3 so that methionine repressed the sterol biosynthesis pathway and increased precursor availability for artemisinic acid biosynthesis. Addition of methionine to the process increased artemisinic acid titers to 1.8 g/L. A dissolved oxygen‐stat algorithm was developed, which simultaneously controlled the agitation and feed pump. This improved process control and increased titers to 2.5 g/L.
Three‐dimensional culture for monoclonal antibody production by hybridoma cells immobilized in macroporous gel particles
Authors: Nilsang Suthasinee , Nehru Vishal , Plieva Fatima M. , Nandakumar Kutty Selva , Rakshit Sudip Kumar , Holmdahl Rikard , Mattiasson Bo , Kumar Ashok 
Published: December 2008

AbstractCell proliferation and long‐term production of monoclonal antibody IgG2b by M2139 hybridoma cells immobilized in macroporous gel particles (MGPs) in packed‐bed reactor were studied for a period of 60 days. The MGPs were made of supermacroporous gels produced in frozen conditions from crosslinked polyacrylamide and modified with gelatin which were housed in special plastic carriers (7 × 9 mm2). Cells were trapped in the interior part of MGPs by attaching to the void space of the gel matrix as three‐dimensional (3D) cultivation using gelatin as a substrate layer. Optimizing productivity by hybridoma cell relies on understanding regulation of antibody production. In this study, the behavior of M2139 cells in two‐dimensional cultures on multiwell plate surfaces was also investigated. The effect of three different medium such as basal medium Dulbecco's modified Eagle's medium (D‐MEM) containing L‐glutamine or L‐glutamine + 2 mM α‐ketoglutarate or L‐alanyl‐glutamine (GlutaMAX™) was studied prior to its use in 3D cultivation. The kinetics of cell growth in basal medium containing L‐glutamine + α‐ketoglutarate was similar to cells grown on GlutaMAX containing medium, whereas D‐MEM containing L‐glutamine showed lower productivity. With the maximal viable cell density (6.85 × 106 cells mL−1) and highest specific mAb production rate (3.9 μg mL−1 10−4 viable cell day−1), D‐MEM‐GlutaMAX was further selected for 3D cultivation. Cells in MGPs were able to grow and secrete antibody for 30 days in packed‐bed batch reactor, before a fresh medium reservoir was replaced. After being supplied with fresh medium, cells again showed continuous growth for another 30 days with mAb production efficiency of 50%. These results demonstrate that MGPs can be used efficiently as supporting carrier for long‐term monoclonal antibody production.
Forecasting for fermentation operational decision making
Authors: Montague Gary A. , Martin Elaine B. , O'Malley Christopher J. 
Published: December 2008

AbstractAn awareness of the likely future behavior of a batch or a fed‐batch fermentation process is valuable information that can be exploited to improve product consistency and maximize profitability. For example, by making operational policy changes in a feedforward control sense, improved consistency can be facilitated, while prior knowledge of batch productivity, or the end time, can help determine the downstream processing configuration and upstream process scheduling. In this article, forecasting methods based on multivariate batch statistical data analysis procedures are contrasted with case‐based reasoning (CBR). Additionally, the importance of appropriate statistical data prescreening and the choice of a suitable metric for case selection are investigated. Two industrial case studies are considered, a fed‐batch pharmaceutical fermentation and a batch beer fermentation process. It is demonstrated that, following appropriate statistical prescreening of the data, in terms of forecasting performance, CBR is comparable to linear projection to latent structures (PLS), for the more straightforward problem, i.e., the batch beer fermentation, while for the more complex case—the pharmaceutical process—CBR exhibits enhanced performance over PLS.
Biomimetic macroporous hydrogel scaffolds in a high‐throughput screening format for cell‐based assays
Authors: Dainiak Maria B. , Savina Irina N. , Musolino Isabella , Kumar Ashok , Mattiasson Bo , Galaev Igor Yu. 
Published: December 2008

AbstractMacroporous hydrogels (MHs) hold great promise as scaffolds in tissue engineering and cell‐based assays. In this study, the possibility of combination of three‐dimensional (3D) cell culture with a miniaturized screening format was demonstrated on human colon cancer HCT116, human acute myeloid leukemia KG‐1 cells, and embryonic fibroblasts cultured on MHs (12.5 mm × 7.1 mm I.D.) in a 96‐minicolumn plate format. MHs were prepared by cryogelation technique and functionalized by coating with type I collagen and by copolymerization with agmatine‐based mimetic of cell adhesive peptide RGD (abRGDm). Cancer cells formed multicellular aggregates while fibroblasts formed adhesions on abRGDm‐containing and collagen‐MHs but not on plain MHs, as was demonstrated by scanning electron microscopy. HCT116 and KG‐1 cells grown as aggregates were more resistant to the treatment with cis‐diaminedichloroplatinum (II) (cisplatin) and cytosine 1‐β‐D‐arabinofuranoside (Ara‐C), respectively, during the first 18–24 h of incubation, than single cells grown on unmodified MH. HCT116 cells grown as 2D cultures in conventional 96‐well tissue culture plates were 1.5‐ to 3.5‐fold more sensitive to the treatment with 70 μM cisplatin than cells in 3D cultures in functionalized MHs. Further development of the described experimental system including matching of a specific cell type with appropriate extracellular matrix (ECM) components and 3D cocultures on ECM‐modified MHs may provide a realistic in vitro experimental model for high‐throughput toxicity tests.