bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of vessel height and top‐section size on the hydrodynamic characteristics of airlift fermentors
Authors: Russell A. B. , Thomas C. R. , Lilly M. D. 
Published: December 2004

AbstractFermentations of the yeast Saccharomyces cerevisiae were carried out in a 90 to 250‐L working volume concentric tube airlift fermentor. Measurements of liquid circulation velocity, gas hold‐up, and liquid mixing were made under varying conditions of gas flowrate, vessel height, and top‐section size. Both liquid circulation velocity and mixing time increased with vessel height. Liquid velocity varied approximately in proportion to the square root of column height, supporting a theoretically based relationship. The effect of vessel height on gas hold‐up was negligible. The height of the top‐section had a significant effect on liquid mixing. Mixing time decreased with increasing size of the top‐section up to a critical height. As the top‐section was expanded beyond this height, little improvement in mixing was seen. This indicated the presence of a two‐zone flow pattern in the top‐section. Liquid velocity and gas hold‐up were essentially independent of top‐section height. © 1994 John Wiley & Sons, Inc.
Cell aggregation and neurite growth in gels of extracellular matrix molecules
Authors: Krewson Christine E. , Chung Sonia W. , Dai Weiguo , Mark Saltzman W. 
Published: December 2004

AbstractComponents of the extracellular matrix are believed to guide both nerve cells and neurites to their targets during embryogenesis and, therefore, might be useful for controlling regeneration of nervous tissue in adults. To study the influence of extracellular conditions on neurite outgrowth and cell motility, PC12 cells were suspended in three‐dimensional gels containing (i) collagen (0.4 to 2 mg/mL), (ii) collagen (1 mg/mL) with added fibronectin or laminin (1 to 100 μg/mL), and (iii) agarose (7 mg/mL) with added collagen (0.001 to 1 mg/mL). Neurite outgrwoth was stimulated with nerve growth factor (NGF) and both the extent of neurite outgrowth ad cell aggregation were quantitated over 10 to 12 days in culture. The extent of neurite outgrowth was greatest at the lowest collagen concentration tested (0.4 mg/mL) and decreased with increasing concentration. The addition of laminin or fibronectin altered the extent of neurite outgrowth in collagen gels, but the differences were small. Although no neurite growth was observed in pure agarose gels, considerable neurite outgrowth occurred with the addition of small amounts (≥0.01 mg/mL) of collagen. Mean aggregate size increased more quickly in gels with lower concentrations of collagen. For cells in 1.0 mg/mL collagen, a four‐ to fivefold increase in aggregate volume was seen between days 2 and 10 o the culture period, whereas the increase in DNA content during this same period was less than twofold, suggesting that the cells were aggregating, not multiplying. These results suggest that the composition of the matrix supporting nerve cells has a significant effect on both neurite outgrowth and cell motility. © 1994 John Wiley & Sons, Inc.
Analysis of endothelial cell locomotion: Differential effects of motility and contact inhibition
Authors: Lee Y. , McIntire L. V. , Zygourakis K. 
Published: December 2004

AbstractVideo microscopy and digital time‐lapse recording were used to monitor locomotion and proliferation of bovine pulmonary artery endothelial (BPAE) cells cultured with varying concentrations of basic fibroblast growth factor (bFGF). Cell trajectories were reconstructed using a generalized nearest‐neighbor algorithm and analyzed to determine how cell motility is affected by cell‐cell collisions, cell divisions, and increasing cell density. The temporal evolution patterns of the average speed of locomotion for all cells in a culture were computed and the effects of varying bFGF concentrations were analyzed. Intermediate concentrations of bFGF (30 and 50 ng/mL) significantly increased the speed of locomotion above the levels we observed with 0 and 100 ng/mL concentrations of bFGF. Increases in cell density due to proliferation were immediately accompanied by a decrease in the average speed of locomotion of the cell population. Finally, the effect of bFGF concentration on the overall cell proliferation rates was assessed. With the addition of 30 or 50 ng/mL of bFGF to the culture media, the observed cell proliferation rates increased significantly. The proliferation rates decreased when the bFGF concentration increased to 100 ng/mL. These results show that bFGF concentrations that increase the motility of BPAE cells also increase the observed cell proliferation rates. © 1994 John Wiley & Sons, Inc.
Isolated hepatocytes in a bioartificial liver: A single group view and experience
Authors: Rozga Jacek , Morsiani Eugenio , Lepage Elaine , Moscioni Albert D. , Demetriou Achilles A. , Giorgio Todd 
Published: December 2004

AbstractDespite recent advances in medical supportive therapy, patients with severe fulminant hepatic failure (FHF) have mortality rate approaching 90%. Investigators have attempted to improve survival by using various extracorporeal liver support systems loaded with sorbents and liver tissue preparations. None of them succeeded in gaining clinical acceptance and orthotopic liver transplantation (OLT) remains a primary therapeutic option for patients with FHF. In this study, authors discuss the systems which utilize isolated hepatocytes. Most of these devices were tested in vitro and in animals with chemically and surgically induced liver failure. In some studies, signficant levels of detoxification and liver functions were achieved. The authors describe their own hepatocyte‐based artificial liver (BAL). It is based on plasma perfusion through a hollow‐fiber module seeded with matrix‐anchored porcine hepatocytes. The BAL was used 14 times to treat 9 patients with acute liver failure. On 10 occasions, a charcoal column was included in the plasma circuit. Each treatment lasted 7 ± 1 h. All procedures were tolerated well and 8 patients (including 6 patients with FHF) underwent OLT. Five patients with increased intracranial pressure (ICP) and evidence of decerebration had normalization of ICP and enjoyed full neurologic recovery after OLT. Laboratory data showed evidence for bilirubin conjugation, decrease in blood ammonia, maintenance of low lactic acid levels, and increase in the ration between the branched chain and aromatic amino acids. No allergic reactions to xenogeneic hepatocytes were observed. The authors conclude that BAL treatment with porcine hepatocytes appears to be safe and can help maintain patients alive and neurologically intact until a liver becomes available for transplantation. © 1994 John Wiley & Sons, Inc.
Mini‐review: Islet transplantation to create a bioartificial pancreas
Authors: Mikos Antonios G. , Papadaki Maria G. , Kouvroukoglou Stylianos , Ishaug Susan L. , Thomson Robert C. 
Published: December 2004

AbstractDonor scarcity precludes the use of pancreatic transplantation to treat type I diabetes. Xenogeneic islet transplantation offers the possibility of overcoming this problem; however, it entails the use of immunoisolation devices to prevent immune rejection of the transplanted islets. These devices consist of a semipermeable membrane, which surrounds the islets and isolates them from the host's immune system, while allowing the passage of insulin and essential nutrients, including glucose. Problems associated with proposed device designs include diffusion limitations, biocompatibility, device retrieval in the event of failure, and mechanical integrity. Microencapsulation appears to be the most promising system of immunoisolation, however, the design of a device suitable for human clinical use remains a challenge. © 1994 John Wiley & Sons, Inc.
Tissue engineering of a bioartificial kidney
Authors: Cieslinski Deborah A. , David Humes H. 
Published: December 2004

AbstractTissue engineering is a rapidly growing field in biotechnology. The use and packaging of synthetic materials, biologic compounds, and cellular components of specific tissues can be envisioned to replace physiologic function of diseased organs. Long‐term ex vivo therapy for kidney failure has been achieved, so that the kidney may be the first solid organ in which tissue engineering concepts can produce an implantable device for long‐term in vivo replacement therapy. To replace the kidney's excretory function, an implantable bioartificial kidney requires both a device to replace blood ultrafiltration performed by renal glomeruli and a device to replace transport regulatory function of the renal tubule. The initial concepts for these devices are just beginning to be considered and developed. © 1994 John Wiley & Sons, Inc.
A near‐infrarod spectroscopy technique for the control of fermentation processes: An application to lactic acid fermentation
Authors: Vaccari Giuseppe , Dosi Elisabetta , Campi Anna L. , Mantovani Giorgio , González‐Vara y R. Antonio , Matteuzzi Diego 
Published: December 2004

AbstractA near‐infrared (NIR) spectroscopy technique for the control of lactic acid fermentation process has been proposed. Lactic acid, glucose, and biomass concentrations were determined by the NIR spectroscopy method. The three parameters examined were closely correlated to the results obtained with classical laboratory procedures. Moreover, the conditions for the on‐line utilization of the NIR spectroscopy measurement system were pointed out. The great versatility of the NIR spectroscopy should permit its use for other fermentation processes. © 1994 John Wiley & Sons, Inc.
Polymer–polymer organic solvent two‐phase system: A new type of reaction medium for bioorganic synthesis
Authors: Otamiri Marina , Adlercreutz Patrick , Mattiasson Bo 
Published: December 2004

AbstractMixing solutions of polymers dissolved in chloroform resulted in turbid solutions that parted into two separate phases upon standing. Each phase consisted primarily of one of the two polymers and contained only small amounts of the other. An enzyme (α‐chymotrypsin) added to the two‐phase system partitioned preferentially to one of the phases; this was observed with native enzyme and with enzyme associated with one of the polymers through non‐convalent interactions. Under the conditions studied, α‐chymotrypsin was active and expressed even higher activity and stability than native enzyme added to the organic solvent without polymer. An emulsion was easily formed on mixing with small droplets of one of the phases suspended in the other phase. By operating with the enzyme in the emulsion, a very attractive system for carrying out enzyme‐catalyzed conversions was created. Short diffusion distances and minimized steric hindrance are two characteristics of such systems. At the conclusion of the reaction, stirring/mixing was ceased and, after phase separation, it was possible to recover the enzyme as well as the product, under ideal conditins, from different phases. The enzyme was then reused. © 1994 John Wiley & Sons, Inc.
Purification of monoclonal antibodies from whole hybridoma fermentation broth by fluidized bed adsorption
Authors: Thömmes Jörg , Halfar Markus , Lenz Suzanne , Kula Maria‐Regina 
Published: December 2004

AbstractTo achive the coarse purification of a monoclonal antibody from whole hybridoma fermentation broth a fluidized bed cation exchange process was used. The procedure consisted of application of the crude sample and washing of the bed in a fluidized mode and elution in a fixed bed mode. A completely clarified eluate was obtained with purification factors between 4 and 8 and a concentration of the desired product (monoclonal antibody) by a factor of more than 3 was achived. Thus, a combination of the three early steps of the downstream process clarification, concentration and coarse purification was possible. Two different materials were tested: a commercially available agarose‐based matrix (Stream‐line‐SP), and a self‐derivatized material based on controlled‐pore glass (Bioran). Initial experiments were performed to describe the fluidization of the glass material. Comparison with the agarose material showed several differences, the agarose matrix allowing liquid flow closer to plug flow than the glass material. Increased backmixing in the liquid phase was detected when fluidizing the glass adsorbent compared with the agarose‐based matrix. Despite this fact, comparison of the two materials with respect to antibody binding and elution demonstrated a similar performance. © 1995 John Wiley & Sons, Inc.
Modeling of anaerobic formate kinetics in mixed biofilm culture using dynamic membrane mass spectrometric measurement
Authors: Dornseiffer P. , Meyer B. , Heinzle E. 
Published: December 2004

AbstractThe dynamics of the anaerobic conversion of formate in a microbial mixed culture taken from an anaerobic fluidized bed reactor was studied using a new stirred micro reactor equipped with a membrane mass spectrometer. The microreactor with a toroidally shaped bottom and pitched blade turbine and a cylindrical flow guide was thermostated and additionally equipped with a pH electrode and pH control. During fed‐batch experiments using formate, the dissolved gases (methane, hydrogen, and carbon dioxide), as well as the acid consumption rates for pH control were monitored continuously. Initially and at the end of each experiment, organic acids were analyzed using ion chromatography (IC). It was found that about 50% of the formate was converted to methane via hydrogen and carbon dioxide, 40% gave methane either directly or via acetate. This was calculated from experiments using H13CO3− pulses and measurement of 12CH4 and 13CH4 production rates. About 10% of the formate was converted to lactate, acetate, and propionate, thereby increasing the measured CO2/CH4 production ratio. The nondissociated formic acid was shown to be rate determining. From the relatively high Ks value of 2.5 mmol m−3, it was concluded that formate cannot play an important role in electron transfer. During dynamic feeding of formate, hydrogen concentration always increased to a maximum before decreasing again. This peak was found to be very discriminative during modeling. From the various models set up, only those with two‐stage degradation and double Monod kinetics, both for CO2 and hydrogen, were able to describe the experimental data adequately. Additional discrimination was possible with the IC measurement of organic acids. © 1995 John Wiley & Sons, Inc.
Effect of surfactant and particle size reduction on hydrolysis of deinking sludge and nonrecyclable newsprint
Authors: Duff Sheldon J. B. , Moritz John W. , Casavant Tracy E. 
Published: December 2004

AbstractDisposal of sludge from deinking mills represents a significant proportion of operating costs. Bioconversion of the cellulosic fraction of deinking sludge (DIS) to ethanol greatly reduces disposal costs while producing an environmentally friendly fuel. In this study, the cellulosic fraction of newsprint and deinking sludge was hydrolysed to produce fermentable sugars. For newsprint, a particle size of 1 to 1.5 mm provided optimal reaction rates in batch reactors over practical hydrolysis times, and reducing sugar concentrations as high as 35 g/L could be achieved using a fed‐batch reactor configuration. For both newsprint and DIS, the hydrolysis rate increased nonlinearly with enzyme loading. Tween‐80 only marginally improved sugar production but was able to release sugars from cellulosic substrates in the absence of lytic enzymes, in an amount proportional to the surfactant concentration and the substrate particle size. DIS was relatively recalcitrant to enzymatic hydrolysis, possibly due in part to inhibition by hydrophobic constituents. © 1995 John Wiley & Sons, Inc.
Enzymic peptide synthesis in microaqueous, solvent‐free systems
Authors: Kuhl P. , Elchhorn U. , Jakubke H.‐D. 
Published: December 2004

AbstractThermolysin‐catalyzed (EC 3.4.24.4) and chymotrypsin‐catalyzed (EC 3.4.21.1) peptide synthesis reactions were accomplished without any organic solvent in the presence of low amounts of water under sonication and fluidization. The systems used are considered to be microaqueous solvent‐free ones. The influence of several reaction parameters, such as time, the amount of enzyme, the amount of water in free form or bound as hydration water, and the N/C component ratio, on the vield of the thermolysin‐catalyzed synthesis of Z–Phe–Leu–NH2 (up to 87% yield) was investigated in a sonicated system. Besides Z–Phe–Leu–NH2, the tripeptide derivatives Ac–Xaa–Trp–Leu–NH2, (Xaa = Gly, Ala) were also obtained in good yields of 79 and 71% respectively. In the latter case, no hydrolytic side reactions were observed. Using a fluidized‐bed reactor, chymotrypsin‐ and thermolysin‐catalyzed syntheses of N‐protected di‐ and tripeptide amides could be perfromed with yields in the range of 10 to 40%. © 1995 John Wiley & Sons, Inc.
Polyphenoloxidases immobilized in organic gels: Properties and applications in the detoxification of aromatic compounds
Authors: Crecchio C. , Ruggiero P. , Pizzigallo M. D. R. 
Published: December 2004

AbstractGelatine gels originate from water in oil microemulsions in which the ternary system consists of isooctane/ sulfosuccinic acid bis [2‐ethyl hexyl] ester/water; the solubilization of gelatin in the water pool of these microemulsions transforms them into viscous gels in which it is possible to cosolubilize various reactive molecules. These gels were used to immobilize two phenoloxidases, a laccase from Trametes versicolor and a tyrosinase from mushroom. The best balance between gel retention and catalytic activity was reached at a gelatine concentration of 2.5% (w/v) in the case of tyrosinase, while laccase immobilization was independent of gelatine concentration. Both enzymes kept the same optimum pH as the corresponding soluble controls, while a partial loss of activity was observed when they were immobilized. Immobilized enzymes showed an increased stability when incubated for several days at 4°C with a very low release from the gels in the incubation solutions. The immobilization of tyrosinase and of laccase enhanced stability to thermal inactivation. Furthermore, gel‐entrapped tyrosinase was almost completely preserved from proteolysis: more than 80% of the activity was maintained, while only 25% of the soluble control activity was detected after the same proteolytic treatments. A column packed with gel‐immobilized tyrosinase was used to demonstrate that enzymes immobilized with this technique may be reused several times in the same reaction without loosing their efficiency. Finally, gel‐entrapped tyrosinase and laccase were capable of removing naturally occurring and xeno‐biotic aromatic compounds from aqueous suspensions with different degrees of efficiency. © 1995 John Wiley & Sons, Inc.
N‐glycans of recombinant human interferon‐γ change during batch culture of chinese hamster ovary cells
Authors: Hooker Andrew D. , Goldman Merlin H. , Markham Nicola H. , James David C. , Ison Andrew P. , Bull Alan T. , Strange Philip G. , Salmon Ian , Baines Anthony J. , Jenkins Nigel 
Published: December 2004

AbstractA recombinant Chinese hamster ovary (CHO) cell line making human interfron‐γ (IFN‐γ) was grown in 12‐L stirred tank fermentors in three batch fermentations under conditions of constant temperature, pH, and dissolved oxygen tension. In addition to cell growth, metabolite, and productivity data, a detailed analysis of the carbohydrate structures attached to each glycosylation site of IFN‐γ was achieved using matrix‐assisted laser desorption mass spectrometry (MALDI‐MS) in combination with exoglycosidase array sequencing. Complex biantennary oligosaccharides (particularly Gal2GlcNAc4Man3which was core ℵl‐6 fucosylated at Asn25but not at Asng97) were most prevalent at both glycosylation sites. However, considerable microheterogeneity arising from the presence of triantennary and truncated glycan structures was also observed. The proportion of the dominant core glycan structure (Gal2GlcNAc4Man3± Fuc1) decreased by 15–26% during batch culture, with increases in the proportion of oligomannose and truncated glycans over the same time period. Prolonged culture resulting from an extended lag phase led to further accumulation of oligomannose and truncated structures, reaching up to 52% of total glycans attached to Asng97by 240 h of culture. The implications of these glycosylation changes for optimizing the time for harvesting cell cultures, and for the clearance of recombinant therapeutic products in vivo are discussed. © 1995 John Wiley & Sons, Inc.
Less Symmetrical Dicopper(II) Complexes as Catechol Oxidase Models—An Adjacent Thioether Group Increases Catecholase Activity
Authors: Merkel Michael , Möller Niclas , Piacenza Manuel , Grimme Stefan , Rompel Annette , Krebs Bernt 
Published: December 2004

AbstractThree new unsymmetrical compartmental dinucleating ligands, 4‐bromo‐2‐(4‐methylpiperazin‐1‐ylmethyl)‐6‐[{2‐(1‐piperidyl)ethyl}aminomethyl]phenol (HL1), 4‐bromo‐2‐(4‐methylpiperazin‐1‐ylmethyl)‐6‐[{2‐(morpholin‐4‐yl)ethyl}aminomethyl]phenol (HL2), and 4‐bromo‐2‐(4‐methylpiperazin‐1‐ylmethyl)‐6‐[{2‐(thiomorpholin‐4‐yl)ethyl}aminomethyl]phenol (HL3), have been synthesized in order to model the active site of type 3 copper proteins. The dicopper(II) complexes of these ligands give first hints about the influence of a thioether group close to the metal site. The bromophenol‐based ligands have one piperazine arm and one other bidentate arm in positions 2 and 6 of the phenolic ring, respectively. With each ligand a dinuclear copper(II) complex was prepared and structurally characterized. The copper ions were found to have square pyramidal environments and a mixture of endogenous phenoxo and exogenous acetate bridging. The influence of a heteroatom in one arm of the ligand on catecholase activity and speciation in solution was studied by UV/Vis spectroscopy, ESI‐MS experiments and, DFT calculations.
Bilayer Vesicles of Amphiphilic Cyclodextrins: Host Membranes That Recognize Guest Molecules
Authors: Falvey Patrick , Lim Choon Woo , Darcy Raphael , Revermann Tobias , Karst Uwe , Giesbers Marcel , Marcelis Antonius T. M. , Lazar Adina , Coleman Anthony W. , Reinhoudt David N. , Ravoo Bart Jan 
Published: December 2004

AbstractA family of amphiphilic cyclodextrins (6, 7) has been prepared through 6‐S‐alkylation (alkyl=n‐dodecyl and n‐hexadecyl) of the primary side and 2‐O‐PEGylation of the secondary side of α‐, β‐, and γ‐cyclodextrins (PEG=poly(ethylene glycol)). These cyclodextrins form nonionic bilayer vesicles in aqueous solution. The bilayer vesicles were characterized by transmission electron microscopy, dynamic light scattering, dye encapsulation, and capillary electrophoresis. The molecular packing of the amphiphilic cyclodextrins was investigated by using small‐angle X‐ray diffraction of bilayers deposited on glass and pressure–area isotherms obtained from Langmuir monolayers on the air–water interface. The bilayer thickness is dependent on the chain length, whereas the average molecular surface area scales with the cyclodextrin ring size. The alkyl chains of the cyclodextrins in the bilayer are deeply interdigitated. Molecular recognition of a hydrophobic anion (adamantane carboxylate) by the cyclodextrin vesicles was investigated by using capillary electrophoresis, thereby exploiting the increase in electrophoretic mobility that occurs when the hydrophobic anions bind to the nonionic cyclodextrin vesicles. It was found that in spite of the presence of oligo(ethylene glycol) substituents, the β‐cyclodextrin vesicles retain their characteristic affinity for adamantane carboxylate (association constant Ka=7.1×103 M−1), whereas γ‐cyclodextrin vesicles have less affinity (Ka=3.2×103 M−1), and α‐cyclodextrin or non‐cyclodextrin, nonionic vesicles have very little affinity (Ka≈100 M−1). Specific binding of the adamantane carboxylate to β‐cyclodextrin vesicles was also evident in competition experiments with β‐cyclodextrin in solution. Hence, the cyclodextrin vesicles can function as host bilayer membranes that recognize small guest molecules by specific noncovalent interaction.