bluuebunny/crossref_metadata_2025 huggingface dataset:
Cover Picture: 1D Arrangement of Au Nanoparticles by the Helical Structure of Schizophyllan: A Unique Encounter of a Natural Product with Inorganic Compounds (Angew. Chem. Int. Ed. 13/2005)
Authors: Bae Ah‐Hyun , Numata Munenori , Hasegawa Teruaki , Li Chun , Kaneko Kenji , Sakurai Kazuo , Shinkai Seiji
Published: March 2005

A linear array of nanoparticles can be generated by the use of an appropriate template. The cover picture shows a TEM image of such a 1D array of gold nanoparticles, aligned by the use of the β‐1,3‐glucan polysaccharide schizophyllan, which adopts a triple‐helical structure in aqueous solution. In their Communication on page 2030 ff., S. Shinkai and co‐workers describe how the hydrophobic inner cavity of the helix hosts the hydrophobic nanoparticles and aligns the guests along its length.
The impact of impermanent Web‐located citations: A study of 123 scholarly conference publications
Authors: Sellitto Carmine
Published: March 2005

In this article the results of research that examined the permanence of 1,068 Web‐located citations in 123 academic conference articles published between 1995 and 2003 are reported. The study is one of the few but increasing number of investigations that examines the growing practice of authors citing URLs (Uniform Resource Locators) in their publications to support and argue their scholarly research. It was found that some 46% of all citations to Web‐located sources could not be accessed—with the HTTP 404 (“Page not found”) message (61.5%) being the greatest cause of missing citations. Collectively, the missing citations accounted for 22.0% of all citations, which represents a significant reduction in the theoretical knowledge base underpinning many scholarly articles. It is argued that the consequences of disappearing Web‐located citations has led to diminishing opportunities for future researchers to examination the underlaying foundations of discourse and argument in scholarly articles.
Expression of epidermal growth factor receptor, ERBB2 and KIT in adult soft tissue sarcomas
Authors: Sato Osamu , Wada Takuro , Kawai Akira , Yamaguchi Umio , Makimoto Atsushi , Kokai Yasuo , Yamashita Toshihiko , Chuman Hirokazu , Beppu Yasuo , Tani Yoichi , Hasegawa Tadashi
Published: March 2005

BACKGROUND

Little is known about the expression of receptor tyrosine kinases in adult soft tissue sarcomas (STS). In the current study, the authors analyzed the expression of epidermal growth factor receptor (EGFR), ERBB2, and KIT in 281 patients with STS who were treated in a single institution. Verification of the presence of an association with prognosis was performed.

METHODS

The current study included 281 adult patients with STS of the extremity and trunk who were diagnosed and treated in the National Cancer Center, Tokyo. Expression was assessed using immunohistochemical stains for EGFR, ERBB2, and KIT on formalin‐fixed, paraffin‐embedded tissue sections by standard avidin‐biotin peroxidase complex technique and EGFR detection system.

RESULTS

Positive staining of EGFR was observed in 168 of 281 (60%) patients. Positive staining was common in pleomorphic malignant fibrous histiocytomas (89%), myxofibrosarcomas (89%), synovial sarcomas (76%), malignant peripheral nerve sheath tumors (89%), and leiomyosarcomas (73%). It was less common in well differentiated liposarcomas (38%), fibrosarcomas (36%), and myxoid liposarcomas (6%). In contrast, positive staining of ERBB2 and KIT was very limited. Increased levels of EGFR were significantly associated with a decreased probability of overall survival (P = 0.01), although by univariate analysis; probability of overall survival at 5 years was 64% in patients with increased levels of EGFR and 79% in patients without such overexpression. The overexpression of EGFR was significantly associated with histologic grade (P < 0.001). Moreover, stratified log‐rank test revealed that there is an interrelation between EGFR overexpression and histologic grade.

CONCLUSIONS

EGFR overexpression was found to be a negative prognostic factor of adult STS, which is strongly associated with histologic grade. STS patients with EGFR overexpression may benefit from treatment with currently available biospecific inhibitors for EGFR. Cancer 2005. © 2005 American Cancer Society.
Phase I dose‐escalation study of tezacitabine in combination with 5‐fluorouracil in patients with advanced solid tumors
Authors: Bendell Johanna C. , Eder Joseph P. , Clark Jeffrey W. , Fidias Panagiotis , Lynch Thomas J. , Seiden Michael V. , Ryan David P.
Published: March 2005

BACKGROUND

Tezacitabine [(E)‐2'‐deoxy‐2'‐(fluoromethylene) cytidine; FMdC] is a novel nucleoside analog with potent antiproliferative and antitumor activity in preclinical studies. A tolerable safety profile and clinical activity have been shown in Phase I and Phase II clinical studies. The purpose of the current open‐label, Phase I dose‐escalation trial was to evaluate the combination of tezacitabine and 5‐fluorouracil (5‐FU) in the treatment of patients with advanced solid tumors.

METHODS

Twenty‐four patients with a variety of advanced solid tumors for which there was no curative therapy were enrolled. Bolus infusion tezacitabine was administered on Day 1 of a 14‐day cycle at escalating doses of 150–350 mg/m2, with continuous infusion 5‐FU (CI 5‐FU) given on Days 1–7 at a fixed dose of 200 mg/m2 per day. Patients underwent objective tumor evaluation by radiologic methods or clinical examination at baseline and after every fourth treatment cycle.

RESULTS

The maximum tolerated dose of the combination therapy was determined to be tezacitabine, 200 mg/m2, with CI 5‐FU, 200 mg/m2 per day. The toxicities were manageable, the most notable being transient severe (National Cancer Institute Common Toxicity Criteria Grade 3 or 4) neutropenia in 23 patients (96%). Eleven (55%) of the 20 assessable patients had partial responses or stabilization of disease. The highest response rate was in patients with primary tumors of esophageal origin.

CONCLUSIONS

Tezacitabine at a dose of 200 mg/m2 in combination with CI 5‐FU at a dose of 200 mg/m2 per day was relatively well tolerated and had clinical activity in patients with advanced solid tumors, particularly in patients with esophageal and other gastrointestinal carcinomas. Cancer 2005. © 2005 American Cancer Society. Cancer 2005. © 2005 American Cancer Society.
Visual cortical activity during tactile perception in the sighted and the visually deprived
Authors: Sathian K.
Published: March 2005

This article reviews studies demonstrating activity in visual cortex during tactile perception in sighted participants as well as in those who have experienced visual deprivation of varying duration. This field has been very active over the last few years, with the result that a number of exciting findings have emerged, but a unifying framework is still lacking. The first section of this article deals with investigations revealing that visual cortical activity is regularly associated with the neural processing of tactile inputs in normally sighted individuals. Next, the possible reasons underlying such visual cortical recruitment are considered. The focus then shifts to the effects of visual deprivation, examining the involvement of visual cortex in sensory and language processing in the early and late blind. The final section gives an account of studies suggesting that a remarkable degree of plasticity can be observed even after quite short‐lasting visual deprivation. Overall, it appears that the nature of visual cortical activity during nonvisual tasks in the sighted can be influenced by late‐onset blindness and even by brief interruptions of visual input; however, the relevant neural plasticity seems to considerably more exuberant if vision is lost very early in life or was never present, which suggests that there is a critical period for the maximal expression of such plasticity. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 279–286, 2005.
Carbon Nanotube Modified Microelectrode for Enhanced Voltammetric Detection of Dopamine in the Presence of Ascorbate
Authors: Hočevar Samo B. , Wang Joseph , Deo Randhir Prakash , Musameh Mustafa , Ogorevc Božidar
Published: March 2005

A single carbon fiber microelectrode modified with multi‐wall carbon nanotubes (MWCNT) and Nafion exhibits an attractive electroanalytical performance for enhanced voltammetric detection of dopamine in the presence of ascorbate at physiological pH. The fast and simple preparation protocol involves dipping a single carbon fiber microelectrode into a modification solution containing Nafion and MWCNT. The resulting surface modification couples the sensitivity improvement associated with the MWCNT with the permselectivity of Nafion films. The microsensor displays highly linear behavior over the 2 to 20 μM dopamine range examined (R of 0.997), with a detection limit of 70 nM. A highly reproducible response was observed for 50 repetitive measurements with a RSD of 1.6%, while the effect of ascorbate upon the voltammetric signal for dopamine was negligible. In addition, some more insights are given into the electroanalytical performance of the MWCNT/Nafion modified microelectrode. Such a disposable dopamine microsensor holds great promise for convenient detection of dopamine in the presence of ascorbate at physiological concentrations in microvolume samples and at microlocations (e.g., measurement of dopamine under physiological conditions).
Optimized group velocity control scheme and DNS of decaying compressible turbulence of relative high turbulent Mach number
Authors: Li Xinliang , Fu Dexun , Ma Yanwen
Published: March 2005

To overcome the difficulty in the DNS of compressible turbulence at high turbulent Mach number, a new difference scheme called GVC8 is developed. We have succeeded in the direct numerical simulation of decaying compressible turbulence up to turbulent Mach number 0.95. The statistical quantities thus obtained at lower turbulent Mach number agree well with those from previous authors with the same initial conditions, but they are limited to simulate at lower turbulent Mach numbers due to the so‐called start‐up problem. The energy spectrum and coherent structure of compressible turbulent flow are analysed. The scaling law of compressible turbulence is studied. The computed results indicate that the extended self‐similarity holds in decaying compressible turbulence despite the occurrence of shocklets, and compressibility has little effects on relative scaling exponents when turbulent Mach number is not very high. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of telomerase activity and RNA expression in a patient with acute promyelocytic leukemia treated with all‐trans retinoic acid
Authors: Akiyama Masaharu , Yamada Osamu , Yanagisawa Takaaki , Fujisawa Kohji , Eto Yoshikatsu , Yamada Hisashi
Published: March 2005

In this study, we show that all‐trans retinoic acid (ATRA) treatment leads to a rapid decrease in telomerase activity, which was associated with the reduction in myeloblasts and occurs before the appearance of myelocytes, in a patient with acute promyelocytic leukemia (APL). Microarray analysis by ATRA treatment for 48 hr in peripheral blood mononuclear cells (in vivo) and in cultured bone marrow mononuclear cells (in vitro) from a patient with APL revealed upregulation of CD11b, CD11c, CCAAT enhancer binding protein ε, Rb1, Mad, and tumor necrosis factor‐related genes; and downregulation of hTERT, c‐Myc, WT1, bcl‐2, and eukaryotic translation elongation factor 1α2. The results might offer the potential to define the molecular mechanism underlying ATRA‐induced granulocytic differentiation in patients with APL, and provide clues to identify novel molecular therapeutic targets. Pediatr Blood Cancer 2006,46:506–511. © 2005 Wiley‐Liss, Inc.
Thinking about the why of giving
Authors: Gaudiani Claire L.
Published: March 2005

Life does not lay itself out on spreadsheets. Although fundraising management tools are critical, they cannot become so central that we forget the most important question: Why give at all?
Thinking beyond the dollar goal: A campaign as organizational transformation
Authors: O'Brien Carol L.
Published: March 2005

Campaigns are not primarily about raising money. They are catalysts for organizational change and transformation, providing opportunities for sustained focus on vision and values.
Synthesis and characterization of poly(DTC‐b‐PEG‐b‐DTC) triblock and poly(TMC‐b‐DTC‐b‐PEG‐b‐DTC‐b‐TMC) pentablock copolymers and kinetics of the polymerization
Authors: Ling Jun , Chen Wei , Shen Zhiquan
Published: March 2005

Dihydroxyl capped biodegradable poly(DTC‐b‐PEG‐b‐DTC) (BCB) triblock copolymer and poly(TMC‐b‐DTC‐b‐PEG‐b‐DTC‐b‐TMC) (ABCBA) pentablock copolymer have been synthesized by PEG and BCB copolymer as macroinitiator in the presence of yttrium tris(2,6‐di‐tert‐butyl‐4‐methylphenolate). The copolymers without random segments have been thoroughly characterized by 1H, 13C‐NMR, SEC, and DSC. Molecular weights of the obtained copolymers are dependent on the amount of PEGs and coincide with the theoretical values. The exchange reaction of yttrium alkoxide and hydroxyl end group is essential for controlling the products' molecular weight. Their thermal behaviors are relevant to the chain lengths of PEG and PDTC segments. The Monte Carlo method has been developed to estimate the chain propagation constant and exchange reaction constant. In average, one exchange reaction will occur after approximately six monomer molecules insert into the growing chain. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1787–1796, 2005
Nitroxide‐mediated homo‐ and block copolymerization of styrene and multifunctional acryl‐ and methacryl derivatives
Authors: Yin Meizhen , Krause Tilo , Messerschmidt Martin , Habicher Wolf D. , Voit Brigitte
Published: March 2005

The ability of different alkoxyamines (I1, I2, I3, I4, and I5) to initiate controlled radical polymerization of styrene was evaluated. Among them, 2‐hydroxymethyl‐2‐[(2‐methyl‐1‐phenyl‐propyl)‐(1‐phenyl‐ethoxy)‐amino]‐propane‐1,3‐diol (I5) gave the highest polymerization rate of styrene, and the best control over the molecular weight and the molecular weight distribution of polystyrene. Kinetic studies confirmed that with initiator I5 the polymerization of styrene proceeded in a controlled way. The controlled radical homopolymerization of multifunctional acryl‐ and methacryl derivatives using initiator I5 could not be realized as demonstrated by the high polydispersities (PD) obtained. However, it was possible to polymerize multifunctional acryl‐ and methacryl derivatives using a polystyrene macroinitiator (Pst) and, thus, novel amphiphilic block copolymers with a narrow molecular weight distribution were obtained. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1873–1882, 2005
Water‐assisted melt compounding of nylon‐6/pristine montmorillonite nanocomposites
Authors: Yu Zhong‐Zhen , Hu Guo‐Hua , Varlet Joel , Dasari Aravind , Mai Yiu‐Wing
Published: March 2005

An exploratory pioneering study on the fabrication of nylon‐6/montmorillonite (MMT) nanocomposites with the aid of water as an intercalating/exfoliating agent via melt compounding in a twin‐screw extruder was conducted. Commercial nylon‐6 pellets and pristine MMT powder were directly fed into the hopper of the extruder. Water was then injected into the extruder downstream. After interactions with the nylon‐6 melt/pristine MMT system, water was removed from the extruder further downstream via a venting gate. As such, no third‐component residual was left within the extrudates. Transmission electron microscopy micrographs showed that pristine MMT was uniformly dispersed in the nylon‐6 matrix. The contact time between water and the nylon‐6/pristine MMT system inside the extruder was so short that nylon‐6 was subjected to very little hydrolysis, if any. The resultant nanocomposites showed higher stiffness, superior tensile strength, and improved thermal stability in comparison with their counterparts obtained without water assistance and the nylon‐6/organic MMT nanocomposites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1100–1112, 2005
Response of a biphasic poly(n‐hexyl isocyanate)/p‐xylene solution to applied high electric fields
Authors: Menna Todd J. , Filisko Frank E.
Published: March 2005

The effect of a high electric field on a solution of a lyotropic liquid‐crystalline polymer, poly(n‐hexyl isocyanate) in p‐xylene, was studied. The application of a high‐voltage alternating‐current electric field to the biphasic solution resulted in an elongation of the nematic domains in the field direction, the degree of elongation varying approximately with the square of the electric field. At a constant field, the extent of elongation decreased, varying inversely with the frequency in an exponential fashion. The domain structure and thus the molecular orientation were examined to explain these electric field effects. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1124–1133, 2005
Clinical and neurohumoral consequences of diuretic withdrawal in patients with chronic, stabilized heart failure and systolic dysfunction
Authors: Galve Enrique , Mallol Anna , Catalan Robert , Palet Jordi , Méndez Stella , Nieto Elsa , Diaz Anna , Soler‐Soler Jordi
Published: March 2005

Background

Loop diuretics are beneficial in heart failure in the short term because they eliminate fluid retention, but in the long‐term, they could adversely influence prognosis due to activation of neurohumoral mechanisms.

Aims

To explore the changes induced by diuretic withdrawal in chronic nonadvanced heart failure.

Methods

Diuretics were withdrawn in 26 stabilized heart failure patients with systolic dysfunction (ejection fraction [EF]<45%). Clinical status was evaluated by physical exam, exercise capacity (corridor test) and New York Heart Association (NYHA) class. Biochemical and neurohumoral determinations were performed at baseline and at 3 months.

Results

At 3 months, 17 out of 26 patients (65%) were able to tolerate diuretic interruption without a deterioration in exercise capacity or New York Heart Association functional class. Renal function parameters improved (baseline urea 46.2±10.8 to 39.2±10.1 mg/dl at 3 months, p=0.014; creatinine 1.1±0.23 to 0.98±0.2 mg/dl, p=0.013). Glucose metabolism also improved (fasting glucose 151±91 to 122±14 mg/dl, p=0.035). Heart rate and systolic blood pressure did not significantly change, while diastolic blood pressure increased (from 80±10 to 87±13 mm Hg, p=0.006). Neurohumoral determinations showed a decrease in plasma renin activity (4.19±5.96 to 2.88±4.98 ng/ml, p=0.026), with no changes in aldosterone, arginine‐vasopressin, endothelin‐1 and norepinephrine. In contrast, atrial natriuretic peptide significantly increased (115±87 to 168±155 pg/ml, p=0.004).

Conclusion

Diuretic withdrawal in stabilized heart failure with systolic dysfunction is associated with an improvement in renal function parameters, glucose metabolism and some neurohumoral parameters, such as plasma renin activity; however, atrial natriuretic peptide levels increased.
Efficient suppression of the amber codon in E. coli in vitro translation system
Authors: Agafonov Dmitry E. , Huang Yiwei , Grote Michael , Sprinzl Mathias
Published: March 2005

An mRNA encoding the esterase from Alicyclobacillus acidocaldarius with catalytically essential serine codon (ACG) replaced by an amber (UAG) codon was used to study the suppression in in vitro translation system. Suppression of UAG by tRNASer(CUA) was monitored by determination of the full‐length and active esterase. It was shown that commonly used increase of suppressor tRNA concentration inhibits protein production and therefore limits suppression. In situ deactivation of release factor by specific antibodies leads to efficient suppression already at low suppressor tRNA concentration and allows an in vitro synthesis of fully active enzyme in high yield undistinguishable from wild‐type protein.
How to analyze the investment–uncertainty relationship in real option models?
Authors: Lund Diderik
Published: March 2005

The real options tradition originally predicted a decreasing relationship between uncertainty and investment, through the positive effect of higher uncertainty on the trigger level for revenue relative to costs. An opposing effect on the probability of reaching the level has been identified, yielding a total effect with ambiguous sign. This paper makes three points. The “opposing” effect is not always opposing. Systematic risk cannot generally be assumed to increase with volatility. A probability is not the best measure of investment. The sign of the total effect is again ambiguous. This ambiguity is illustrated, depending on specification of model and parameters.
Characterization of Transient Cultures of Clostridium acetobutylicum
Authors: Srivastava Ashok K. , Volesky Bohumil
Published: March 2005

The inability of unstructured mathematical models to acknowledge complex intracellular physiological changes limits their applicability for dynamic culture growth conditions. By considering RNA as a bottleneck growth‐limiting compound, a structured model was developed to describe the transient and steady‐state growth of Clostridium acetobutylicum. The linear relationship between the on‐line NADH fluorescence and the sugar utilization specific rates was incorporated in the mathematical model to facilitate in situ assessment of the culture metabolic activity. The improved performance of the proposed structured model was demonstrated. It simulated the transient culture metabolism better than the unstructured Monod model. However, it still failed to simulate the metabolic switchover between acidogenic and solventogenic Clostridium culture behavior.
Enhancement of External Mass Transfer by Gaseous End Products
Authors: Huisman Jan W. , Van Den Heuvel Johannes C. , Ottengraf Simon P. P.
Published: March 2005

The conversion rate of biological particles is affected by the mass transfer rate in the particle and the surrounding liquid film. The influence of gas production on the external mass transfer rate was investigated in an inorganic model system, consisting of strong acid ion‐exchange particles converting a sodium bicarbonate solution. The enhancement by the evolution of carbon dioxide amounted to a factor of 4 compared to sodium hydroxide as a reference. The consequences of the experimental results for biological systems are discussed, and it is concluded that the conversion rate might considerably be influenced under conditions of low turbulence. However, no substantial acceleration by the investigated mechanism is to be expected for suspended biological particles, due to the relatively low gas flux at the surface of the particle.
Effects of Dissolved Oxygen on Hybridoma Cell Growth, Metabolism, and Antibody Production Kinetics in Continuous Culture
Authors: Ozturk Sadettin S. , Palsson Bernhard Ø
Published: March 2005

The effects of dissolved oxygen concentration (DO) on hybridoma cell physiology were examined in a continuous stirred tank bioreactor with a murine hybridoma cell line (167.4G5.3). Dissolved oxygen concentration was varied between 0% and 100% air saturation. Cell growth and viability, carbohydrate, amino acid, and energy metabolism, oxygen uptake, and antibody production rates were investigated. Cell growth was inhibited at both high and low DO. Cells could grow at 0% DO and maintain viability under a nitrogen atmosphere. Cell viability was higher at low DO. Glucose, glutamine, and oxygen consumption rates changed little at DO above 1 % air saturation. However, the metabolic uptake rates changed below 1 % DO, where growth became oxygen limited, and a Km value of 0.6 % DO was obtained for the specific oxygen uptake rate. The metabolic rates of glucose, glutamine, lactate, and ammonia increased 2‐3‐fold as the DO dropped from 1% to 0%. Amino acid metabolism followed the same general pattern as that of glutamine and glucose. Alanine was the only amino acid produced. The consumption rates of amino acids changed little above 1% DO, but under anaerobic conditions the consumption rates of all amino acids increased severalfold. Cells obtained most of their metabolic energy from glutamine oxidation except under oxygen limitation, when glucose provided most of the energy. The calculated ATP production rate was only slightly influenced by DO and rose at 0% DO. Antibody concentration was highest at 35% DO, while the specific antibody production rate was insensitive to DO.
Plant Cell Culture Using a Novel Bioreactor: The Magnetically Stabilized Fluidized Bed
Authors: Bramble Joye L. , Graves David J. , Brodeliust Peter
Published: March 2005

A novel bioreactor using magnetically stabilized fluidized bed (MSFB) technology has been developed that has certain advantages for cultivating cells continuously. In this system, the cells are protected from shear and are constrained to move through the fermenter in lock‐step fashion by being immobilized in calcium alginate beads. The MSFB permits good mass transfer, minimizes particle collisions, and allows for the production of cells while maintaining a controlled cell residence time. Details of the experimental system are described. In addition, the experimental performance of an MSFB used to grow plant cells in batch mode is compared to the results obtained in shake flask culture.
Quantitation of Cell Area on Glass and Fibronectin‐Coated Surfaces by Digital Image Analysis
Authors: Truskey George A. , Proulx Timothy L.
Published: March 2005

By using digital image processing and analysis, two procedures were developed to rapidly measure the projected area of a field of adherent 3T3 fibroblasts without staining of cell borders. The cell area of newly attached and rounded cells with well‐resolved borders was obtained by a gray value thresholding procedure. For cells that had undergone an appreciable degree of spreading, cell boundaries were less distinct and a nonlinear spatial Sobel filter was used, followed by thresholding. For both procedures, linear relations were observed between cell areas obtained from image analysis and cell areas obtained by tracing. The areas of a population of traced cells were not statistically different from the area distribution obtained by using the standard curves for the processed images. Uncertainty in the estimated mean area depended only upon the number of cells examined. Approximate numbers of cells required to obtain estimates of the mean are calculated. As an application of these procedures, cell areas were measured for 3T3 cells attached to glass and fibronectin‐coated surfaces and were found to be significantly larger for cells spreading on fibronectin‐coated glass than on glass alone. Increased cell area during spreading on fibronectin‐coated surfaces was proportional to increased cell adhesivity after exposure to a shear stress of 58 dyn/cm2.
Rapid Immunoassay Technique for Process Monitoring of Animal Cell Fermentations
Authors: Jervis E. , Kilburn D. G.
Published: March 2005

A calibration and quality control technique suited to process monitoring with immunoassay is demonstrated. The particle concentration fluorescence immunoassay (PC‐FIA) is shown to provide a sensitive and rapid method for the quantification of specific biomolecules in cell cultures. Smoothing of linear calibration parameters is performed by forming weighted averages of standard points as the run progresses. These estimates are then used to determine slope and intercept values for improved calibration. The nonuniformity of the fluorescent signal variance is also considered, and a weight model is developed to describe the relationship between signal fluorescence and signal variance for weighted linear curve fitting. Pooling calibration results over the process run improves overall assay performance as determined by using standard control chart analysis. This method is suitable for semicontinuous monitoring of animal cell fermentations and has been used here to measure cell‐associated and culture supernatant concentrations of monoclonal antibody (Ab) from hybridoma cells. The cell‐associated Ab concentration correlates with cell‐specific production rate. Assay times on the order of 10 min for supernatant and 25–30 min for cell‐associated Ab concentrations can be achieved, making this procedure suitable for process monitoring and control. Under these conditions the assay has a detection limit of approximately 10 ng/mL, providing a sensitive and specific method for the quantification of cell culture constituents.
Protein Recovery from Reversed Micellar Solutions through Contact with a Pressurized Gas Phase
Authors: Phillips John B. , Nguyen Huyen , John Vijay T.
Published: March 2005

We describe a new process for the recovery of encapsulated protein from reversed micellar solution in concentrated form. The method involves desolubilization of the protein by decreasing solvent density through gas dissolution. Under appropriate thermodynamic conditions, the micellar water pool can be converted to clathrate hydrates. Protein recovery is facilitated by clathrate hydrate formation, which causes the desolubilized protein to exist in a solid phase, distinct from the micellar supernatant. The process is carried out without any ionic strength or pH modification.
Enhancing Oxygen Transfer in Bioreactors by Perfluorocarbon Emulsions
Authors: Ju Lu‐Kwang , Lee Jaw Fang , Armiger William B.
Published: March 2005

This work aims to investigate the capability of perfluorocarbon (PFC) emulsions in enhancing oxygen transfer in bioreactors. Based on the penetration theory, a model has been derived for evaluating the potential oxygen transfer enhancement effects of PFC emulsions with very fine PFC particles. Defined as the ratio between the maximum oxygen transfer rates in systems with and without the emulsions, the enhancement factor achievable with dilute PFC emulsions can be estimated as the square root of the product of ratios of oxygen permeability and solubility in media with and without the emulsions. The effect of PFC emulsions on oxygen transfer in low‐shear cultivation systems was further studied experimentally with direct measurements of volumetric oxygen transfer coefficients, 𝔨Lα, in bioreactors and with microbial fermentations conducted under low‐shear conditions. It was found that significantly higher cell populations could be maintained at an aerobic state by using systems supplemented with the investigated emulsions. The experimentally determined values of oxygen transfer enhancement factor compare well with the theoretical values for emulsions with up to 15% (v/v) PFC. The feasibility of enhancing oxygen transfer in bioreactors by introduction of adequate amounts of PFC emulsions was clearly demonstrated.
Protein Isolation by Solution‐Controlled Gel Sorption
Authors: Gehrke Stevin H. , Robeson Julie , Johnson James Fred , Vaid Nitin
Published: March 2005

Illustrated are the principles for isolating proteins from solution by sorption into a polymer gel phase, driven by the addition of a water‐soluble polymer to the protein solution. The separation is shown to be analogous to conventional two‐phase aqueous extraction. However, the use of a gel phase rather than a solution for absorbing the protein makes separation of the protein from the polymer and the recycling of the gel phase much simpler. The model system used was linear poly(ethylene glycol) (PEG) and dextran gel. Increasing the molecular weight and concentration of the PEG favored sorption by the gel of ovalbumin, bovine serum albumin, cytochrome c, and hemoglobin. The proteins could be quantitatively recovered by immersing the gel in PEG‐free solution.
A Microperifusion System with Environmental Control for Studying Insulin Secretion by Pancreatic Tissue
Authors: Dionne Keith E. , Colton Clark K. , Yarmush Martin L.
Published: March 2005

A continuous flow reactor (perifusion system) was fabricated and tested for measuring the kinetics of insulin secretion from isolated pancreatic islets of Langerhans in response to step changes in the glucose concentration and oxygen partial pressure in the perfusate flowing around the islets. The system was capable of making rapid changes in perfusate glucose concentration and pO2, had rapid dynamic response for measuring the change in insulin secretion rate as a result of these changes in perfusate, and was suitable for studying very small volumes of tissue. Initial experiments with this system demonstrated that (1) the response of isolated rat islets to glucose stimulation was very fast, with the first phase peak occurring in as little as about 10 s, (2) bulk perfusate oxygen partial pressure levels of 30 mmHg or less reduced the second‐phase insulin secretion rate in graded fashion, (3) the reduction in secretion rate began within 1 min following an oxygen partial pressure decrease, and (4) the reduction in secretion rate was reversible, with a burst of insulin secretion occurring during the first minute after partial pressure restoration.
Insect Cell Hosts for Baculovirus Expression Vectors Contain Endogenous Exoglycosidase Activity
Authors: Licari Peter J. , Jarvis Donald L. , Bailey James E.
Published: March 2005

Four different insect cell lines that can be used as hosts for baculovirus infection were assayed for the presence of endogenous exoglycosidases. All four cell lines, derived from Spodoptera frugiperda, Trichoplusia ni, Bombyx mori, or Malacosoma disstria, contained N‐acetyl‐β‐glucosaminidase, N‐acetyl‐β‐galactosaminidase, β‐galactosidase, and sialidase activities. Exoglycosidase activities were found in cell lysates as well as cell‐free supernatants from uninfected and wild‐type baculovirus infected cells. Oligosaccharide analysis of cellular glycoproteins using lectins recognizing Galβ1, 3GalNAc, Galβ1, 4GlcNAc, and NeuAcα2, 6Gal demonstrated that only Galβ1,3GalNAc was present. The demonstration that these cells contain exoglycosidases raises the possibility that the oligosaccharides of baculovirus‐expressed glycoproteins are subject to enzymatic degradation.
Transient Stirred‐Tank Reactors Operating with Immobilized Enzyme Systems: Analysis and Simulation Models and Their Experimental Checking
Authors: Santoyo A. Bódalo , Carrasco J. L. Gómez , Gómez E. Gómez , Rodriguez J. Bastida , Morales E. Martinez
Published: March 2005

A mathematical model applicable to the analysis, design, and simulation of heterogeneous enzymatic processes reacting in a stirred‐tank reactor has been formulated. The model develops the unsteady‐state design equations for such reactors and also the diffusion reaction equation in the spherical catalyst particles for reversible Michaelis—Menten kinetics. This structured general model provides an overview of almost all of the processes occurring in an immobilized enzyme reactor system. Although the analysis presented here is limited to certain situations, it can be extended to other support geometries, enzyme kinetics, and reactor configurations. To check the model, the experimental data obtained with immobilized β‐galactosidase were compared to those theoretically predicted.
Plasmid Stability in Immobilized Mixed Cultures of Recombinant Escherichia coli
Authors: Dincbas Vildan , Hortacsu Amable , Camurdan Agnes
Published: March 2005

The growth behavior of a mixed culture of plasmid‐free and plasmid‐containing (YEp352) Escher chia coli HB101 cells in free suspension and immobilized conditions was studied experimentally. It was found that immobilization in calcium alginate beads delayed the reduction of the plasmid‐containing fraction for a period of time inversely related to the total number of cells initially immobilized. A simple unstructured model that assumes compartmentalization of cells in the immobilization matrix at the beginning of growth gave a fit which was in good agreement with the data.
Preparation and Characterization of Bifunctional Unilamellar Vesicles for Enhanced Immunosorbent Assays
Authors: Jones Matthew A. , Kilpatrick Peter K. , Carbonell Ruben G.
Published: March 2005

Small unilamellar phospholipid vesicles with covalently attached biotin and horseradish peroxidase (HRP) were prepared and characterized in terms of hydrodynamic diameter, amount and activity of immobilized enzyme, and number of biotin molecules on the outer vesicle surface. In addition, the specific adsorption of these bifunctional vesicles and commercially available biotin‐labeled horseradish peroxidase (B‐HRP) to anti‐biotin antibody (ABA) coated polystyrene microtiter plate welis was examined. At low antibody surface densities, the signal (ΔA/min) generated by the vesicles adsorbed to the surface was approximately 100 times higher than the signal generated by B‐HRP. It was also found that the biotin‐conjugated vesicles were able to compete effectively with free biotin in solution for surface ABA sites. These results indicate that this type of vesicle may be used in competitive and sandwich‐type enzyme‐linked immunoassays to improve the detection limits, increase the signal, and decrease the reaction time necessary to detect a given analyte concentration in solution.
Binding Kinetics of Antigen by Immobilized Antibody or of Antibody by Immobilized Antigen: Influence of Lateral Interactions and Variable Rate Coefficients
Authors: Sadana Ajit , Madugula A.
Published: March 2005

Kinetic rate expressions are developed for the binding kinetics of antigen by immobilized antibody or of antibody by immobilized antigen. The influence of lateral interactions leads to variable rate coefficients for adsorption, and these provide a more realistic picture of the events occurring on the surface. Emphasis is placed on the similarities and dissimilarities present in the kinetic rate expressions. A general trend in the rate expressions is observed on going from dual‐step binding to dual‐step binding with lateral interactions. This provides physical insights into the reactions occurring at the surface and helps in their control and stability at the surface.
Construction and Characterization of a Specialized Ribosome System for the Overproduction of Proteins in Escherichia coli
Authors: Leipold Robert J. , Dhurjati Prasad
Published: March 2005

A recombinant Escherichia coli system was constructed to overexpress proteins using the specialized ribosomes developed by Herman de Boer and co‐workers at Genentech. Specialized ribosomes carry a mutation in the anti‐Shine—Dalgarno region of 16 S ribosomal RNA, which is the site of messenger RNA binding. A complementary mutation in the ribosome binding site (the Shine‐Delgarno region) of a particular mRNA results in specific and efficient translation of this mRNA on the specialized ribosomes. Production of β‐galactosidase with this system was characterized with respect to transcription, translation, plasmid replication, and cell growth rate. Translation of specialized mRNA on specialized ribosomes gave 5 times more enzyme activity than did translation of wild‐type mRNA on wild‐type ribosomes under similar conditions. The system described here offers a number of advantages when compared to a similar system described recently: (1) two separate specialized systems were constructed; (ii) the genes for specialized mRNA and specialized rRNA are on separate plasmids, allowing for different combinations of mRNA and rRNA; and (iii) appropriate controls were constructed for each plasmid.
Effects of Oxygen/Glucose/Glutamine Feeding on Insect Cell Baculovirus Protein Expression: A Study on Epoxide Hydrolase Production
Authors: Wang Min‐Ying , Kwong Simon , Bentley William E.
Published: March 2005

The recombinant protein yields for batch cultures of the insect cell baculovirus expression system have been significantly enhanced by oxygen, glucose, and glutamine feeding. The improvement in both volumetric and specific yields was based on influencing the metabolism of infected cells. Oxygen was absolutely required for viral replication and high protein expression in infected cells. Increases of 200% in volumetric yield and 100% in specific yield of recombinant epoxide hydrolase were achieved by controlling the dissolved oxygen (DO) level to near 35% saturation. An additional 100% increase was achieved by glucose and glutamine feeding. Results indicated that the intracellular metabolite pool was not adequate for recombinant protein overproduction. Finally, the specific protein yield, based on initial infection cell density, in high cell density spinner flasks and bioreactors of spent media with glucose and glutamine feeding was equivalent to that of freshly diluted cultures.
Modular Neural Networks for Identification of Starches in Manufacturing Food Products
Authors: Huang Y. W. , Mithani R. , Takahashi K. , Fan L. T. , Seib P. A.
Published: March 2005

Neural network technology, especially that related to or derived from the multilayered Perceptron model with the back‐propagation learning mechanism, has been found to be effective in pattern recognition and classification. Although mentioned infrequently, the number of patterns that can be recognized or classified by a specific neural network based on this technology is inescapably constrained by the network configuration such as the numbers of input, output, and hidden units. A direct expansion, e.g., increasing the numbers of the various units, of an existing network to accommodate additional patterns is usually undesirable for two reasons. First, a complete retraining of the network, incorporating the learned and new patterns as the training set, is necessary. Second, such a retraining almost always proceeds at a decreasing rate and is more difficult to converge. Both of these problems can be circumvented, at least partially, by resorting to the concept of modular neural networks. In the present work, each of two multilayered neural networks is trained to recognize eight types of starches used in foods. Subsequently, the two trained networks are coupled as modules of a final network. The learning rate of the final network is found to be much faster than that of a nonmodularized network with the same configuration.
Evaluation of Column Flotation in the Downstream Processing of Fermentation Products: Recovery of a Genetically Engineered α‐Amylase
Authors: Miranda Everson A. , Berglund Kris A.
Published: March 2005

Flotation is a simple, inexpensive, and versatile unit operation with a largely unexplored potential in biotechnology. There is a general lack of research concerning biotechnological applications in this area, especially in the recovery of fermentation products. Moreover, the few reports in the literature do not consider the modern concept of column flotation as practiced in the mineral industry. We report herein the application of column flotation for the recovery of a Bacillus stearothermophilus α‐amylase expressed in Escherichia coli by the use of a food‐grade polymer, (hydroxypropyl)methylcellulose (HPMC), and ammonium sulfate. First, the enzyme was removed from the liquid phase by partition to a salted‐out HPMC phase. The enzyme‐containing polymer floes were then floated from the liquid. Recovery of active enzyme was as high as 90%, with throughput as high as 94 m3/(h.m2). The floatability of the enzyme from a periplasmic extract was higher than extracellular enzyme in the broth due to the presence of depressors of molecular weight lower than 10 000 in the broth.
The Thickness of Shock Layers in Liquid Chromatography
Authors: Zhu Jie , Ma Zidu , Guiochon Georges
Published: March 2005

At high concentrations, one boundary (the front if the isotherm is convex upward) of the elution band of a single component becomes very steep. Similarly, in frontal analysis, the same boundary is self‐sharpening. These steep boundaries are called shock layers. They result from the steady‐state equilibrium between a nonlinear thermodynamics of phase equilibrium on the one hand, which tends to create a concentration discontinuity, and axial dispersion and a finite rate of mass transfer on the other hand, which tend to relax the concentration gradient. We show that the width of experimental breakthrough curves recorded in frontal analysis agrees well with the prediction of the shock layer theory of Rhee and Amundson in the high concentration range. It is a function of the coefficients of the column HETP equation and the height of the concentration step and is independent of the column length, after the steady state is achieved. In the low concentration range, a discrepancy is observed when the column length is short and the migration distance is insufficient to achieve constant pattern behavior.
Mathematical Modeling of Inhibition Kinetics in Acetone–Butanol Fermentation by Clostridium acetobutylicum
Authors: Yang Xiaoping , Tsao George T.
Published: March 2005

Acetone–butanol fermentation by Clostridium acetobutylicum suffers from severe product inhibition effects. This paper presents the results of studies on the cell growth kinetics of the culture under the inhibition of multiple products/byproducts. The inhibition effects caused by multiple components simultaneously as well as a single product alone were examined. Fractional factorial experiments were conducted, and statistical analysis of the study results was performed. Acetate, butyrate, butanol, and pH were found to exhibit synergistic inhibitory effects on the cell growth of C. acetobutylicum. Ethanol and acetone alone or in the presence of other products did not show inhibitory effects under the experimental conditions. Among the various mathematical forms of equations that were evaluated, a parabolic form was found to be most suitable for describing the overall synergistic inhibitory effects caused by acetate, butyrate, butanol, and pH. The simulation results achieved by using the model were promising.
Shallow intrusive processes during 2002–2004 and current volcanic activity on Mt. Etna
Authors: Patanè Domenico , Mattia Mario , Aloisi Marco
Published: March 2005

The understanding of shallow intrusive processes during 2002–2004, as well as the causes of the volcano‐tectonic seismicity, has been improved at Mt. Etna by comparing the inversion results from GPS data with accurate 3D hypocentral locations. Our findings indicate that short periods of deflation (about six months) were followed by recharging phases after the end of both the 2001 and 2002–2003 flank eruptions. During the last recharging phase (June 2003–August 2004), modeling results and seismic observations suggest a composite mechanism of re‐injection of magma into the rift‐zones (S and NE), similar to that leading to the 2002–2003 flank eruption, which could have triggered the summit eruption started on September 7, 2004.
Prediction of a new phase transition in Al2O3 at high pressures
Authors: Caracas R. , Cohen R. E.
Published: March 2005

We use density functional theory to investigate several high‐pressure polymorphs of Al2O3 and predict a new stable polymorph at high pressures with post‐perovskite structure. The ambient pressure Rc corundum phase transforms to the Pbcn Rh2O3(II) structure at about 104 GPa. At about 156 GPa, the Rh2O3(II) structure transforms further to the Cmcm post‐perovskite structure. The Al2O3 Pbnm perovskite structure is metastable at all pressures with respect to corundum, Rh2O3(II) and post‐perovskite. The metastable perovskite to post‐perovskite transition takes place at about 120 GPa, which is above the same transition in MgSiO3. Thus the presence of Al2O3 in the lower mantle, dissolved in MgSiO3 perovskite, will increase the transition pressure to post‐perovskite. Our calculations also show that Al2O3 is most likely dissolved in the post‐perovskite phase of MgSiO3, increasing its stability at high pressures.