bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zero‐Inflated Negative Binomial Mixed Regression Modeling of Over‐Dispersed Count Data with Extra Zeros
Authors: Yau Kelvin K. W. , Wang Kui , Lee Andy H. 
Published: June 2003

AbstractIn many biometrical applications, the count data encountered often contain extra zeros relative to the Poisson distribution. Zero‐inflated Poisson regression models are useful for analyzing such data, but parameter estimates may be seriously biased if the nonzero observations are over‐dispersed and simultaneously correlated due to the sampling design or the data collection procedure. In this paper, a zero‐inflated negative binomial mixed regression model is presented to analyze a set of pancreas disorder length of stay (LOS) data that comprised mainly same‐day separations. Random effects are introduced to account for inter‐hospital variations and the dependency of clustered LOS observations. Parameter estimation is achieved by maximizing an appropriate log‐likelihood function using an EM algorithm. Alternative modeling strategies, namely the finite mixture of Poisson distributions and the non‐parametric maximum likelihood approach, are also considered. The determination of pertinent covariates would assist hospital administrators and clinicians to manage LOS and expenditures efficiently.
Optimal Representation of Supplementary Variables in Biplots from Principal Component Analysis and Correspondence Analysis
Authors: Graffelman Jan , Aluja‐Banet Tomàs 
Published: June 2003

AbstractThis paper treats the topic of representing supplementary variables in biplots obtained by principal component analysis (PCA) and correspondence analysis (CA). We follow a geometrical approach where we minimize errors that are obtained when the scores of the PCA or CA solution are projected onto a vector that represents a supplementary variable. This paper shows that optimal directions for supplementary variables can be found by solving a regression problem, and justifies that earlier formulae from Gabriel are optimal in the least squares sense. We derive new results regarding the geometrical properties, goodness of fit statistics and the interpretation of supplementary variables. It is shown that supplementary variables can be represented by plotting their correlation coefficients with the axes of the biplot only when the proper type of scaling is used. We discuss supplementary variables in an ecological context and give illustrations with data from an environmental monitoring survey.
Novel type of in situ extraction: Use of solvent containing microcapsules for the bioconversion of 2‐phenylethanol from L‐phenylalanine by Saccharomyces cerevisiae
Authors: Stark D. , Kornmann H. , Münch T. , Sonnleitner B. , Marison I. W. , von Stockar U. 
Published: June 2003

AbstractA novel in situ product removal (ISPR) method that uses microcapsules to extract inhibitory products from the reaction suspension is introduced into fermentation technology. More specifically, L‐phenylalanine (L‐Phe) was transformed by Saccharomyces cerevisiae to 2‐phenylethanol (PEA), which is inhibitory toward the yeast. In order to continuously remove PEA from the vicinity of the cells, the reaction suspension was brought into contact with capsules of 2.2‐mm diameter that had a hydrophobic core of dibutyl sebacate and an alginate‐based wall. This novel process combines the advantages of a normal in situ extraction process (fast mass transfer and simple process set‐up) with the benefits of a membrane‐based process (reduction of the solvent toxicity and avoidance of stable emulsions). In particular, the microbial cells are shielded from the phase toxicity of the organic solvent by a hydrogel layer surrounding the organic core. By placing the microcapsules into the fermenter, the final overall concentration of PEA in a fed‐batch culture was increased from 3.8 to 5.6 g/L because a part of the inhibitory product dissolved in the dibutyl sebacate core. In another fermentation experiment, the capsules were placed in a fluidized bed that was connected via a loop to the fermenter. In addition, the fluidized bed was connected via a second loop to a back‐extractor to regenerate the capsules. By alternating the extraction and back‐extraction cycles, it was possible to limit the PEA concentration of the fed‐batch culture in the fermenter to 2.4 g/L while producing important quantities of PEA that accumulated in an external reservoir. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 376–385, 2003.
Micro‐assembly of functionalized particulate monolayer on C18‐derivatized SiO2 surfaces
Authors: Huang Tom T. , Geng Tao , Akin Demir , Chang Woo‐Jin , Sturgis Jennifer , Bashir Rashid , Bhunia Arun K. , Robinson J. Paul , Ladisch Michael R. 
Published: June 2003

AbstractThis work describes a simple approach to immobilize functionalized colloidal microstructures onto a C18‐coated SiO2 substrate via specific or non‐specific bio‐mediated interactions. Biotinylated bovine serum albumin pre‐adsorbed onto a C18 surface was used to mediate the surface assembly of streptavidin‐coated microbeads (2.8 μm), while a bare C18 surface was used to immobilize anti‐Listeria antibody‐coated microbeads (2.8 μm) through hydrophobic interactions. For a C18 surface pre‐adsorbed with bovine serum albumin, hydrophobic polystyrene microbeads (0.8 μm) and positively charged dimethylamino microbeads (0.8 μm) were allowed to self‐assemble onto the surface. A monolayer with high surface coverage was observed for both polystyrene and dimethylamino microbeads. The adsorption characteristics of Escherichia coli and Listeria monocytogenes on these microbead‐based surfaces were studied using fluorescence microscopy. Both streptavidin microbeads pre‐adsorbed with biotinylated anti‐Listeria antibody and anti‐Listeria antibody‐coated microbeads showed specific capture of L. monocytogenes, while polystyrene and dimethylamino microbeads captured both E. coli and L. monocytogenes non‐specifically. The preparation of microbead‐based surfaces for the construction of microfluidic devices for separation, detection, or analysis of specific biological species is discussed. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 416–427, 2003.
Combined sequence and structure analysis of the fungal laccase family
Authors: Kumar S. V. Suresh , Phale Prashant S. , Durani S. , Wangikar Pramod P. 
Published: June 2003

AbstractPlant and fungal laccases belong to the family of multi‐copper oxidases and show much broader substrate specificity than other members of the family. Laccases have consequently been of interest for potential industrial applications. We have analyzed the essential sequence features of fungal laccases based on multiple sequence alignments of more than 100 laccases. This has resulted in identification of a set of four ungapped sequence regions, L1–L4, as the overall signature sequences that can be used to identify the laccases, distinguishing them within the broader class of multi‐copper oxidases. The 12 amino acid residues in the enzymes serving as the copper ligands are housed within these four identified conserved regions, of which L2 and L4 conform to the earlier reported copper signature sequences of multi‐copper oxidases while L1 and L3 are distinctive to the laccases. The mapping of regions L1–L4 on to the three‐dimensional structure of the Coprinus cinerius laccase indicates that many of the non‐copper‐ligating residues of the conserved regions could be critical in maintaining a specific, more or less C‐2 symmetric, protein conformational motif characterizing the active site apparatus of the enzymes. The observed intraprotein homologies between L1 and L3 and between L2 and L4 at both the structure and the sequence levels suggest that the quasi C‐2 symmetric active site conformational motif may have arisen from a structural duplication event that neither the sequence homology analysis nor the structure homology analysis alone would have unraveled. Although the sequence and structure homology is not detectable in the rest of the protein, the relative orientation of region L1 with L2 is similar to that of L3 with L4. The structure duplication of first‐shell and second‐shell residues has become cryptic because the intraprotein sequence homology noticeable for a given laccase becomes significant only after comparing the conservation pattern in several fungal laccases. The identified motifs, L1–L4, can be useful in searching the newly sequenced genomes for putative laccase enzymes. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 386–394, 2003.
Optimal covalent immobilization of glucose oxidase‐containing liposomes for highly stable biocatalyst in bioreactor
Authors: Wang Shaoqing , Yoshimoto Makoto , Fukunaga Kimitoshi , Nakao Katsumi 
Published: June 2003

AbstractThe glucose oxidase‐containing liposomes (GOL) were prepared by entrapping glucose oxidase (GO) in the liposomes composed of phosphatidylcholine (PC), dimyristoyl L‐α‐phosphatidylethanolamine (DMPE), and cholesterol (Chol) and then covalently immobilized in the glutaraldehyde‐activated chitosan gel beads. The immobilized GOL gel beads (IGOL) were characterized to obtain a highly stable biocatalyst applicable to bioreactor. At first, the glutaraldehyde concentration used in the gel beads activation as well as the immobilizing temperature and time were optimized to enhance the immobilization yield of the GOL to the highest extent. The liposome membrane composition and liposome size were then optimized to obtain the greatest possible immobilization yield of the GOL, the highest possible activity efficiency of the IGOL, and the lowest possible leakage of the entrapped GO during the GOL immobilization. As a result, the optimal immobilization conditions were found to be as follows: the liposome composition, PC/DMPE/Chol = 65/5/30 (molar percentage); the liposome size, 100 nm; the glutaraldehyde concentration, 2% (w/v); the immobilizing temperature, 4°C; and the immobilizing time, 10 h. Furthermore, the optimal IGOL prepared were characterized by its rapidly increasing effective GO activity to the externally added substrate (glucose) with increasing temperature from 20 to 40°C, and also by its high stability at 40°C against not only the thermal denaturation in a long‐term (7 days) incubation but also the bubbling stress in a bubble column. Finally, compared to the conventionally immobilized glucose oxidase (IGO), the higher operational stability of the optimal IGOL was verified by using it either repeatedly (4 times) or for a long time (7 days) to catalyze the glucose oxidation in a small‐scale airlift bioreactor. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 444–453, 2003.
Growth dynamics of Artemisia annua hairy roots in three culture systems
Authors: Kim Yoo Jeong , Weathers Pamela J. , Wyslouzil Barbara E. 
Published: June 2003

AbstractThe transient growth of Artemisia annua hairy roots was compared for cultures grown in shake flasks and in bubble column and mist reactors. Instantaneous growth rates were obtained by numerically differentiating the transient biomass measurements. Specific sugar consumption rates showed good agreement with literature values. From the growth rate and sugar consumption rate, the specific yield and maintenance coefficient for sugar were determined for all three culture systems. These values were statistically indistinguishable for roots grown in shake flasks and bubble columns. In contrast, the values for roots grown in bubble columns and mist reactors were statistically different, suggesting that sugar utilization by roots grown in these two systems may be different. By measuring respiration rates in the bubble column reactor we also determined the actual biomass yield and maintenance coefficient for O2 and CO2. Together with an elemental analysis of the roots, this allowed us to obtain a reasonable carbon balance. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 428–443, 2003.
Effect of heat on phycoerythrin fluorescence: Influence of thermal exposure on the fluorescence emission of R‐phycoerythrin
Authors: Vaidya S. , Orta‐Ramirez A. , Smith D. M. , Ofoli R. Y. 
Published: June 2003

AbstractThe goal of this work was to measure and model the effect of thermal exposure on the fluorescence emission of R‐phycoerythrin (R‐PE). The long‐term objective of our work is to assess the feasibility of encapsulating R‐PE for use as the critical component of a time‐temperature integrator (TTI) for ascertaining the degree of inactivation of food pathogens such as Salmonella. In this article we present a study to measure and model the thermally induced fluorescence emission decay of R‐PE in several isothermal experiments. We used the isothermal data to determine the kinetic parameters, based on a general nth order reaction, and evaluated the utility of the resulting model by using it to predict R‐PE fluorescence emission decay for several nonisothermal experiments based on published USDA safe harbor guidelines for cooked beef products. The transient experiments were conducted over the same temperature range used in the isothermal study. Very good agreement was obtained between theory and experiment at temperatures of 62.8°C and above, although the model slightly underpredicted the extent of fluorescence emission decay at 60°C. Our results indicate that R‐PE fluorescence emission decay kinetics is well behaved and that the protein is a strong candidate for use as a time‐temperature integrator. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 465–473, 2003.
Scale‐down of continuous filtration for rapid bioprocess design: Recovery and dewatering of protein precipitate suspensions
Authors: Reynolds T. , Boychyn M. , Sanderson T. , Bulmer M. , More J. , Hoare M. 
Published: June 2003

AbstractThe early specification of bioprocesses often has to be achieved with small (tens of millilitres) quantities of process material. If extensive process discovery is to be avoided at pilot or industrial scale, it is necessary that scale‐down methods be created that not only examine the conditions of process stages but also allows production of realistic output streams (i.e., streams truly representative of the large scale). These output streams can then be used in the development of subsequent purification operations. The traditional approach to predicting filtration operations is via a bench‐scale pressure filter using constant pressure tests to examine the effect of pressure on the filtrate flux rate and filter cake dewatering. Interpretation of the results into cake resistance at unit applied pressure (α) and compressibility (n) is used to predict the pressure profile required to maintain the filtrate flux rate at a constant predetermined value. This article reports on the operation of a continuous mode laboratory filter in such a way as to prepare filter cakes and filtrate similar to what may be achieved at the industrial scale. Analysis of the filtration rate profile indicated the filter cake to have changing properties (compressibility) with time. Using the insight gained from the new scale‐down methodology gave predictions of the flux profile in a pilot‐scale candle filter superior to those obtained from the traditional batch filter used for laboratory development. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 454–464, 2003.
Enzymatic catalysis via liquid–liquid interfaces
Authors: Straathof Adrie J.J. 
Published: June 2003

AbstractEnzymes acting in a biphasic liquid of water and organic solvent may show catalytic activity dependent on the amount of phase interface available. Such an effect may be caused by several mechanisms. For example, for hydroxynitrile lyase from Prunus amygdalus, substrate mass transfer limitation has been advocated, but also adsorption of the enzyme on the interface. In this commentary it is shown that often these two mechanisms will have qualitatively similar consequences. The reaction rate will be influenced by the organic substrate concentration, by the initial enzyme concentration, and by the volume‐specific interfacial area, and these influences will be linear at low values but reach a saturation level at high values. To rule out any of the models, their quantitative mathematical descriptions should be compared, taking into account that both models may be valid simultaneously. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83:371–375, 2003.
Biofiltration of a mixture of volatile organic compounds on granular activated carbon
Authors: Aizpuru A. , Malhautier L. , Roux J. C. , Fanlo J. L. 
Published: June 2003

AbstractThe performance of a biofilter packed with Active Carbon (AC) was evaluated. The effluent (alcohol, ketones, esters, aromatic and chlorinated compounds) treated was a representative mixture of most common industrial emissions. To achieve a better knowledge of multicomponent adsorption mechanisms, and to underline the interest of inoculating AC, a control abiotic humidified filter had been operated in the same conditions as the biofilter. For a load of 110 g VOC m−3 AC h−1, after 55 days of operation, the removal efficiency was higher in the biotic than in the abiotic filter (85% vs 55%, respectively). Moreover, in the biofilter, at steady state, the elimination of all compounds was almost complete except for chlorinated compounds and p‐xylene (removal efficiency of 25% and 64%, respectively). The microbial colonization of AC involved a decrease of the adsorption sites accessibility and enhanced the treatment of VOCs (volatile organic compounds) having a lower affinity for activated carbon. Moreover, while aromatic compounds and MIBK were eliminated along the overall height of the biofilter, pollutants with reduced affinity for AC, such as methanol, acetone, and halogenated compounds were only treated on the second half of the reactor. Thus, the affinity for activated carbon was an important parameter controling the biodegradation process. Nevertheless, the use of AC as packing material in biofilters treating complex mixtures of VOCs is limited. Actually, similar removal efficiency could be reached, in the same conditions, for a biofilter packed with granular peat. Furthermore, for the biofilter packed with AC, the column height necessary to remove biodegradable compounds, with reduced affinity for the support, was important. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 479–488, 2003.
Vascular changes in duodenal mucosa in shigellosis and cholera
Authors: Koshi Rachel , Chandy George , Mathan Minnie , Mathan V.I. 
Published: June 2003

AbstractVascular endothelial cells are highly specialized cells with numerous sensory and modulator functions. Our previous studies show extensive microvascular changes in rectal mucosal vasculature of patients with acute infective diarrhea (Mathan and Mathan 1985a, Gut 26:710–717).We looked for changes in the duodenal mucosal vasculature in two naturally occurring diarrheal infections: shigellosis and cholera. Duodenal mucosal biopsies from 14 patients with shigellosis, 12 patients with cholera, and 10 healthy volunteers were examined under the electron microscope. There were extensive microvascular changes in the duodenum in shigellosis and cholera. Congestion and dilatation of capillaries and venules, stagnation of blood, thinning of the endothelial lining, and platelet clumping were commonly seen in both conditions. Endothelial damage was also common to both conditions but was mild to moderate in cholera and severe in shigellosis with frank hemorrhage, frequent formation of stress fibers, widening of intercellular spaces, cytoplasmic blebbing, cell fragmentation, and intravascular thrombosis. Erythrocyte aggregates, platelet aggregates, and leucocyte plugging lead to capillary obstruction. The arterioles were severely constricted. These changes in the endothelial lining of the microvasculature could contribute to the pathogenesis of the disease resulting in peripheral vascular insufficiency, inadequate oxygen delivery to intestine, and organ dysfunction. The factors influencing these changes, their implications, and possible therapeutic interventions are discussed. Clin. Anat. 16:317–327, 2003. © 2003 Wiley‐Liss, Inc.
Plastination and computerized 3D reconstruction of the temporal bone
Authors: Qiu Ming‐Guo , Zhang Shao‐Xiang , Liu Zheng‐Jin , Tan Li‐Wen , Wang Yu‐Su , Deng Jun‐Hui , Tang Ze‐Sheng 
Published: June 2003

AbstractThe purpose of this study was to generate a computerized 3D reconstruction of the temporal bone and intratemporal structures. A plastination technique was used to obtain equidistant serial thin sections of 1.2 mm thickness and, on an SGI workstation, a Contour‐Marching Cubes algorithm was selected to reconstruct the temporal bone and intratemporal structures in three dimensions. All reconstructed structures can be represented individually or jointly and rotated in any plane. Any diameter and angle of a structure can be conveniently measured. The capability of reconstructing individual and combined images of intratemporal structures, viewing them from all surgical angles, and accurately measuring their spatial relationships gives skull base and otologic surgeons important guidance. The reconstructed model can also be used for resident education, rehearsal of an unfamiliar surgery, and for developing a new surgical approach. Clin. Anat. 16:300–303, 2003. © 2003 Wiley‐Liss, Inc.
Calcaneal angle in Ugandans
Authors: Igbigbi P.S. , Mutesasira A.N. 
Published: June 2003

AbstractWe investigated the calcaneal angle from 206 unilateral radiographs of the lateral aspect of the foot in Ugandans, comprising 114 males and 92 females, aged 20–40 years. The mean angle in males was 35.1° with a standard deviation (SD) of 7.5° and, in females, 37.6° with SD 5.6°. The range of the angle for both sexes together was 20–50° with females having a significantly higher mean value than males (P < 0.01). There was also a significant difference in the angle between Ugandan and Nigerian men (P < 0.01) and between Ugandan and Nigerian women (P < 0.001). Our reported range was the widest so far documented in Africans. Our study reinforces the need to establish the normal range of the angle in a given population and also highlights the clinical importance of the angle to orthopedic surgeons managing calcaneal fractures in this part of the world. Clin. Anat. 16:328–330, 2003. © 2003 Wiley‐Liss, Inc.
Anatomical variations and clinical implications of the artery to the lingual nerve
Authors: Harn Stanton D. , Durham Timothy M. 
Published: June 2003

AbstractThe pterygomandibular space is a critical anatomic area for the delivery of local anesthesia in the practice of dentistry. The neurovascular contents of this area are subject to trauma and its resultant local and systemic complications. This study of 202 cadaveric specimens reaffirms the literature as to the percent distributions of the superficial and deep routes of the maxillary artery and details for the first time the anatomic variations of the artery to the lingual nerve. This artery courses through the pterygomandibular space placing it at risk for injection trauma along with the other neurovascular contents. It has been uncommonly identified and referred to in the literature, yet it may be the first artery encountered when entering the space with a needle or during surgical intervention in the area. Clin. Anat. 16:294–299, 2003. © 2003 Wiley‐Liss, Inc.