bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic Esterification by Surfactant‐Coated Lipase in Organic Media
Authors: Goto Masahiro , Kamiya Noriho , Miyata Masaki , Nakashio Fumiyuki 
Published: March 2005

AbstractSurfactant‐coated lipases have been prepared with a synthesized surfactant. Preparation conditions to obtain a suitable surfactant‐coated lipase were investigated. The enzymatic activity of the lipase in an organic solvent significantly increased with the coating of the surfactant. The esterification rate from the surfactant‐coated lipase was much higher than that from the powder lipase. An aliphatic solvent showed higher activity than did alcohol, aromatic, and chloric solvents. Among them, isooctane gave the highest activity. The reactivity of the surfactant‐coated lipase depends on the pH of the aqueous solution in the preparation and on the buffer solution. Surfactant‐coated lipase prepared in the middle pH range using phosphate buffer showed high enzymatic activity. The surfactant‐coated lipase was thermostable at high temperature compared to the native lipase. A kinetic study enabled a ping‐pong bi‐bi reaction mechanism with alcohol inhibition to be suggested. From the kinetic analysis, it was found that an alcohol substrate inhibits enzymatic esterification by lipase. The reaction rate of the coated lipase was about 100 times that of the powder lipase.
Intracellular Expression of Vitreoscilla Hemoglobin Alters the Aerobic Metabolism of Saccharomyces cerevisiae
Authors: Chen Wilfred , Hughes Dallas E. , Bailey James E. 
Published: March 2005

AbstractVitreoscilla hemoglobin (VHb) has been expressed in Saccharomyces cerevisiae, and its influence on yeast aerobic metabolism has been investigated. New expression vectors were constructed to express VHb constitutively under the control of the ADH‐1 promoter. The presence of VHb was shown by Western blot analysis. VHb has been shown to localize predominantly in the cytoplasm. Batch fermentation results indicated that the wild‐type strain expressing VHb exhibited a shift in the carbon flux toward ethanol production, with no significant alteration in the specific growth rate. This effect was not observed if cells were grown under respiration inhibition, indicating that the metabolic effect of VHb is likely linked to respiration. Expression of VHb in the adh° strain MC65‐2A, which produces ethanol only via a respiration‐coupled pathway, revealed that ethanol production was decreased and cells reached a higher final cell density in a culture of the VHb‐expressing strain. Growth enhancement due to expression of VHb was observed only during the final stage of culture growth when the acetaldehyde produced during the first growth phase was used as a substrate. This metabolic effect of intracellular VHb was seen more clearly in an acetaldehyde fed‐batch fermentation in which VHb‐expressing cells grew to at least 3‐fold higher final cell density. These results suggest that the action of VHb is likely linked to electron transfer.
A Model of Mechanical Changes in Biomaterials at and around Their Glass Transition
Authors: Peleg Micha 
Published: March 2005

AbstractThe transition of biological and food materials from a glassy to a leathery or rubbery state and the accompanying loss of stiffness, hardness, or strength are tranditionally described by a relationahip between the magnitudes of these parameters and the temperature, moisture, or water activity. At the transition region, the curve depicting such a relationship has a sigmoidal shape that can be described by the model, Y(X) = Ys/{1 + exp[X ‐ Xc)/a]}, where X is either temperature, moisture content, or water activity, Y(X) is a mechanical parameter (e. g., modulus), Ys is the latter's magnitude in the glassy state (assumed to be practically constant), Xc is a characteristic temperature, moisture, or aw level of the transition, and a is a constant. This model was tested with the published data of various biomaterials (baker's yeast, casein, coffee creamer, luncheon meat, sodium caseinate, sucrose/glucose glass, wheat grains, and bread). In all cases, it gave a consistent description of the mechanical changes at and around the transition and had a very satisfactory fit.
Modeling of Bacterial Growth under Multiply‐Limiting Conditions. Experiments under Carbon‐ or/and Nitrogen‐Limiting Conditions
Authors: Straight Jeffrey V. , Ramkrishna Doraiswami 
Published: March 2005

AbstractAs the limiting substrate is altered, a microorganism's internal structure is also altered by invoking different metabolic pathways for the utilization of the limiting substrate. Transitions between pathways are moderated by the processes of metabolic regulation and are observed under steady‐state and transient conditions. Under nitrogen‐limited steady‐state conditions, the effects of overflow metabolism are observed in the form of polysaccharide synthesis and excess carbon oxidation, two phenomena that are not observed under carbon‐limited conditions. Furthermore, during transient periods following dilution rate shifts, metabolic lags are observed to be a function of the size of the shift as well as the limiting substrate. The latter observation indicates the preference of one reaction pathway over another as the status of glucose or NH4+ is altered from limiting to nonlimiting. This paper presents steady‐state and transient results from continuous culture experiments using Escherichia coli W. Singly‐limiting conditions, when either glucose or ammonia is the limiting substrate, are investigated. Transient conditions are created by quickly increasing or decreasing the dilution rate of the fermentor. By utilizing the control strategies identified by Straight and Ramkrishna (1994) for regulating the processes commonly found within metabolic pathways, a cybernetic model is developed and compared to the steady‐state and transient experimental results. Due to the incorporation of metabolic pathways, the development of the model accounts for lumped biosynthetic intermediates in addition to key enzymes that catalyze different cellular processes. The model also accounts for an internal resource that is optimally allocated toward the synthesis of the key enzymes. Furthermore, the model incorporates the effects of maintenance processes and overflow metabolism. Upon incorporating nitrogen utilization, the kinetic aspects of the model do not explicitly reduce to those of previous cybernetic models; however, the regulatory structure is in complete agreement with previous cybernetic models proposed for carbon utilization.
Optimum Infection Conditions for Recombinant Protein Production in Insect Cell (Bm5) Suspension Culture
Authors: Zhang Junli , Kalogerakis Nicolas , Behie Leo A. , Iatrou Kostas 
Published: March 2005

AbstractThe baculovirus/insect cell expression system is an efficient and practical method for the production of many active therapeutic proteins on a large scale. The advantages of suspension cultures have been demonstrated with the study of a baculovirus/insect cell (BmNPV/Bm5) expression system for the production of recombinant chloramphenicol acetyltransferase (CAT), a model heterologous protein. Key infection parameters such as infection time and multiplicity of infection were examined systematically for the maximization of protein production. Furthermore, emphasis was placed on the development of possible medium replenishment strategies, which were necessary to achieve higher volumetric protein production from the infection of high‐density cell cultures without sacrificing specific protein productivity. The highest protein production was achieved with the infection of suspended cells in the mid to late exponential growth phase.
Effect of Modulated Glucose Uptake on High‐Level Recombinant Protein Production in a Dense Escherichia coli Culture
Authors: Chou Chih‐Hsiung , Bennett George N. , San Ka‐Yiu 
Published: March 2005

AbstractMethyl α‐glucoside (α‐MG) is a metabolically inert glucose analog sharing the same phosphotransferase system with glucose. The potential of using this compound, which acts as a nontoxic competitive inhibitor, to modulate glucose uptake and subsequently reduce the acetate accumulation rate was investigated. In a complex medium, no significant effect on the growth rate was observed when the α‐MG to glucose ratio was low. The effect of α‐MG supplementation on the production of a model recombinant protein, CadA‐β‐galactosidase, under the regulation of a pH‐inducible promoter in a batch culture was also examined. It was observed that the amount of acetate accumulation was drastically reduced in the presence of α‐MG. More importantly, recombinant protein productivity was significantly improved. A very high volumetric productivity of approximately 1.6 g/L recombinant protein in a dense culture with an OD600 of 35 was obtained in a simple batch fermentation. Even at this high cell density, the specific protein productivity was maintained at a high level and was estimated to account for about 40% of the total cellular protein.
Effects of Ionic and Zwitterionic Surfactants on the Stabilization of Bovine Catalase
Authors: Spreti N. , Bartoletti A. , Profio P. Di , Germani R. , Savelli G. 
Published: March 2005

AbstractThe activity and stability of beef liver catalase have been investigated in the presence of different ionic and zwitterionic surfactants. All cationic and zwitterionic surfactants used in this work have no effect on the initial activity of catalase, but several of them allow the enzyme to retain a high residual activity for longer periods of time than those observed in the absence of any additives. However, the interactions between surfactants and catalase appear to be very peculiar, and certain zwitterionic surfactants have been found to remarkably slow down enzyme degradation, with the enzyme completely preserving its activity after several weeks at temperatures of up to 30 °C. This effect is probably due to an interaction between the surfactant and the intersubunit region of the protein; this interaction could stabilize the quaternary structure of the enzyme.
Extractive Cultivation of Escherichia coli Using Poly(ethylene glycol)/Phosphate Aqueous Two‐Phase Systems To Produce Intracellularβ‐Galactosidase
Authors: Kuboi Ryoichi , Umakoshi Hiroshi , Komasawa Isao 
Published: March 2005

AbstractEscherichia coli cells were found to grow in poly(ethylene glycol) (PEG)/phosphate aqueous two‐phase systems by selecting the phase‐forming components and their concentrations, the tie‐line length, and the phase volume ratio properly. The cells cultivated up to an optical density at 660 nm of 1.0 were disrupted by ultrasonic irradiation to release and recover overproduced β‐galactosidase. The surviving cells were found to grow immediately after ultrasonic irradiation. The PEG/phosphate (KH2‐PO4‐K2HPO4) system with added Na2SO4 was the one optimized for extractive cultivation of E. coli cells, where β‐galactosidase was selectively partitioned to the top phase while total soluble proteins and cells partitioned to the bottom phase. This integrated process was extended to a semicontinuous operating mode, where the top phase containing β‐galactosidase was removed following intermittent ultrasonic irradiation and the bottom phase containing cells was recycled together with the new top phase solution to repeat production and recovery of β‐galactosidase.
Surfactant‐Coated Lipase Suitable for the Enzymatic Resolution of Menthol as a Biocatalyst in Organic Media
Authors: Kamiya Noriho , Goto Masahiro , Nakashio Fumiyuki 
Published: March 2005

AbstractEnantioselective esterification of menthol with fatty acids using a surfactant‐coated lipase was carried out in organic media. The surfactant‐coated lipase originating from Candida cylindracea appeared to be highly enantioselective and good biocatalyst for the resolution of racemic menthol. The enzymatic activity of the lipase in organic media was significantly increased by a coating with a nonionic surfactant. The reaction rate of the coated lipase was more than 100 times that of the powder lipase. In order to investigate the effect of the organic solvent on enantioselectivity, 19 kinds of solvents were employed. The nature of the organic solvent strongly affected the efficiency of the biocatalyst and the enantioselectivity. Among them, isooctane was the best organic solvent from the viewpoint of reaction rate and enantioselectivity. The effect of reaction temperature on esterification was also investigated. The optimal reaction temperature was around 35 °C. The enzymatic activities using n‐saturated fatty acids with different alkyl chain lengths were compared, and long‐chain fatty acids were found to be better substrates than shorter ones. The relationship between the initial rate of the esterification and the carbon number of the fatty acid was not linear. These results suggest that there are inherent Km values for each fatty acid.
Tissue Plasminogen Activator Coexpressed in Chinese Hamster Ovary Cells with α(2,6)‐Sialyltransferase Contains NeuAcα(2,6)Galβ(1,4)Gl‐N‐AcR Linkages
Authors: Minch Sherrill L. , Kallio Pauli T. , Bailey James E. 
Published: March 2005

AbstractGenetic alteration of the set of oligosaccharide biosynthesis enzymes expressed in a genetically engineered host cell line is a plausible strategy for manipulating the oligosaccharides on a cloned glycoprotein coexpressed in that cell line. This hypothesis was verified for the particular case of sialylation of recombinant human tissue plasminogen activator (tPA) expressed by an engineered Chinese hamster ovary (CHO) cell line. The gene for rat liver, β‐galactoside α(2,6)‐sialyltransferase (2,6‐ST) was cloned behind the MMTV promoter in the vector pMSG and transfected into a tPA‐expressing CHO cell line. Selected and screened transfectants exhibited significantly greater surface fluorescence than controls in flow cytometric analyses of cells labeled with Sumbacus nigru agglutinin (SNA)‐biotin and streptavidin‐R‐phycoerythrin; SNA specifically binds to NeuAcα(2,6)Galβ(1,4)Glc‐N‐AcR linkages, which are synthesized by 2,6‐ST and which are not normally found on CHO cells. SNA blots of partially purified tPA from the culture supernatant demonstrated that tPA synthesized in the 2,6‐ST transfectants possessed terminal NeuAcα(2,6)Galβ(1,4)Glc‐N‐AcRlinkages, while tPA from the original recombinant CHO cell line did not. Besides possibly allowing the production of glycoproteins in cell culture with glycosylation more closely resembling that in humans, extensions of this strategy have the potential to tailor the pharmacokinetics, targeting, and antigenic properties of cloned glycoproteins.
Model‐Based Optimization of Equipment and Control for Heat Flux Measurements in a Laboratory Fermentor
Authors: Van Kleeff Bastiaan H. A. , Kuenen J. Gijs , Honderd Ger , Heijnen Sef J. 
Published: March 2005

AbstractThe measurement of microbially‐produced heat in standard laboratory fermentors was studied with the help of a mathematical model describing the heat flows. The improvements that were indicated by the modeling work were implemented in the experimental setup. Tests showed that both the standard deviation in the heat measurement and the response time for the experimental setup improved through use of the modeling results.
From liberation to reconstruction: Theory & practice in the life of Harold Wolpe
Authors: Burawoy Michael 
Published: March 2005

Writings from exile have a long and distinguished pedigree. Trotsky wrote his History of the Russian Revolution while in exile in Turkey and The Revolution Betrayedin Norway; Lenin wrote Imperialism: The Highest Stage of Capitalism in Zurich and had to escape to Finland to write State and Revolution; Luxemburg wrote The Accumulation of Capitalin Switzerland, and Gramsci wrote his Prison Notebooksunder the eye of fascist jail guards. Marx wrote his Capital while exiled in London which is also where Harold Wolpe wrote his most important analyses of South Africa. Being in exile gave him the space to develop a new research program for the study of South Africa, its present, its past, and its future.
This is a shortened version of The Harold Wolpe Memorial Lecture, presented in July 2004 in South Africa. Among the ideas on which it reflects are those Wolpe originally published in ROAPE and which this issue revisits. It is not only a tribute to Wolpe's singular contribution to the African liberation struggle but also an acute reflection of the struggles for liberation and reconstruction that lie ahead, the political practice they demand, the uses of state power required for these tasks and the obligations of intellectual responsibility they impose. See, http://www.wolpetrust.org.za/index.htm
Eczema herpeticum: a case report
Authors: KHAN M. S. , SHAW L. , CLARK V. , AFZAL Z. 
Published: March 2005

Summary.Primary herpetic gingivostomatitis is a relatively common and well‐recognized condition that the dental practitioner may encounter in clinical practice. A primary herpetic infection in a child with atopic dermatitis such as eczema, however, predisposes them to eczema herpeticum. This can be a severe and potentially life‐threatening condition. This paper describes one such case, discusses the aetiology, presentation and management of this condition, and highlights the importance of early recognition by the clinician.
The dental management of a patient with hyperimmunoglobulinemia E syndrome: a case report
Authors: MCAULIFFE N. J. , HUNTER M. L. , KAU C. H. , HUNTER B. , KNOX J. 
Published: March 2005

Summary.Hyperimmunoglobulinemia E recurrent infection syndrome (also known as Job's syndrome) is a rare multi‐system primary immunological disorder in which non‐immunological abnormalities of the dentition, bones and connective tissue are also seen. A previous study has reported the occurrence of dental abnormalities in three‐quarters of individuals diagnosed as suffering from this condition. The present authors report the case of a boy whose prolonged retention of the primary dentition was associated with delayed eruption of permanent teeth. They emphasize the need for early intervention in order to help minimize later orthodontic problems.
Provocation of Kainic Acid Receptor mRNA Changes in the Rat Paraventricular Nucleus by Insulin‐Induced Hypoglycaemia
Authors: Koenig J. I. , Cho J. Y. 
Published: March 2005

AbstractHypoglycaemia induced by insulin injection is a powerful stimulus to the hypothalamic‐pituitary‐adrenal (HPA) axis and drives the secretion of corticotropin‐releasing hormone and vasopressin from the neurones in the paraventricular nucleus (PVN), as well as the downstream hormones, adrenocorticotropic hormone and corticosterone. In some brain regions, hypoglycaemia also provokes increases in extracellular fluid concentrations of glutamate. Regulation of glutamatergic mechanisms could be involved in the control of the HPA axis during hypoglycaemic stress and one potential site of regulation might be at the receptors for glutamate, which are expressed in the PVN. Insulin (2.0 IU/kg, i.p.) or saline was administered to adult male Sprague‐Dawley rats and the animals were sacrificed 30 min, 180 min and 24 h after injection. The amount of several kainic acid‐preferring glutamate receptor mRNAs (i.e. KA2, GluR5 and GluR6) were assessed in the PVN by in situ hybridisation histochemistry. Injection of insulin induced a rapid fall in plasma glucose concentrations, which was mirrored by an increase in plasma corticosterone concentrations. KA2 and GluR5 mRNAs are highly expressed within the rat PVN, and responded to hypoglycaemia with robust increases in expression that endured beyond the period of hypoglycaemia itself. However, GluR6 mRNA is expressed in the areas adjacent to the PVN and hypoglycaemic stress failed to alter expression of this mRNA. These experiments suggest that kainic acid‐preferring glutamate receptors are responsive to changes in plasma glucose concentrations and may participate in the activation of the PVN neurones during hypoglycaemic stress.
PROBLEMS OF A CENSUS OF NATIONAL WEALTH
Authors: Kendrick John W. 
Published: March 2005

This paper is essentially a summary of the book Measuring the Nation's Wealth (Volume 29, Studies in Income and Wealth, New York: National Bureau of Economic Research, 1964), which is the report of study directed by the author. The purpose o f the study was to assess the problems and possibilities of conducting a national census of real wealth as a basis for continuing wealth and balance sheet estimates for the U.S. economy, by major sector.It is stressed that the balance sheets and wealth estimates should be designed as a consistent part of an integrated system of national income accounts. Thus, valuation (at market prices and/or depreciated replacement costs), sectoring, and type‐of‐asset detail in the basic data and derived estimates should be compatible with the flow estimates contained in the economic accounts. Consistency of stock and flow estimates facilitates analysis of inter‐relationships, and is helpful in the estimation process.It is recommended that in the U.S. asset data by broad categories be collected as part of the recurring economic censuses and other reporting systems, but that detail on fixed reproducible assets (construction and equipment) at cost, by year or period of acquisition, be obtained from a small sample of respondents in each industry. The detail would be useful in its own right, and also permit revaluation of the assets by use of price indexes and depreciation rates to a current depreciated replacement cost basis. Where feasible, respondent estimates of market values would also be obtained.The proposal is thus a compromise between the Japanese 1955 sample survey of assets, and the detailed wealth inventory of the U.S.S.R. which was begun in 1959. Preliminary work is now underway in the U.S. federal statistical agencies to expand collection of asset data, and to prepare comprehensive wealth estimates in the framework of the national income accounts.