bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic Dipeptide Synthesis by Surfactant‐Coated α‐Chymotrypsin Complexes in Supercritical Carbon Dioxide
Authors: Mishima Kenji , Matsuyama Kiyoshi , Baba Masayoshi , Chidori Masuhiro 
Published: April 2003

AbstractEnzymatic dipeptide synthesis by surfactant‐coated α‐chymotrypsin complexes was performed in supercritical CO2 and liquid CO2 at 308.2 and 333.2 K at pressures of 6.1 and 10.1 MPa. The enzymatic activity of coated α‐chymotrypsin complexes for dipeptides synthesis at 10.1 MPa in supercritical CO2 (SC‐CO2) was higher than that in a liquid CO2 and ethyl acetate solution at 6.1 MPa. The behavior of α‐chymotrypsin in SC‐CO2 was similar to that in liquid ethyl acetate. And increasing the pressure and temperature increased the maximum conversion and the enzymatic reaction rate in SC‐CO2. Furthermore, the control of the water content in the reaction media had a dominant effect on the enzymatic activity. The maximum conversion for the dipeptide synthesis by the surfactant‐coated α‐chymotrypsin was obtained at 4% water content. The α‐chymotrypsin complexes exhibited a higher enzymatic activity than native α‐chymotrypsin in SC‐CO2. The nonionic surfactants l‐glutamic acid dialkyl ester ribitol amide and sorbitan monostearate were more favored than the anionic surfactant sodium bis(2‐ethylhexyl)sulfosuccinate.
Fedbatch Operation Using Clostridium acetobutylicum Suspension Culture as Biocatalyst for Enhancing Hydrogen Production
Authors: Chin Hsien‐Long , Chen Zu‐Shia , Chou C. Perry 
Published: April 2003

AbstractWe demonstrated the feasibility of fedbatch operation using Clostridium acetobutylicum suspension culture as a biocatalyst for the continuous production of hydrogen. The optimum operating pH and temperature of the current cultivation system for hydrogen production were pH 6.0 and 37 °C, respectively. The volumetric loading of the bioreactor for hydrogen production can be as high as 650 mmol hydrogen/L culture with a yield at approximately 2.0 mol hydrogen/mol glucose. Acetate and butyrate made up approximately 80% of the total metabolites. The inhibitory effect from the two metabolites on the hydrogen production process was investigated. Butyrate at a concentration higher than 13 g/L significantly inhibited not only cell growth but also hydrogen production (i.e., specific hydrogen production rate). Acetate appears to be less toxic than butyrate to the hydrogen production process. While significantly inhibiting cell growth, acetate hardly affected hydrogen production. Finally, the factors limiting cultivation performance were discussed and possible strategies for enhancing the production of hydrogen were proposed.
Containment of Biogenic Sulfide Production in Continuous Up‐Flow Packed‐Bed Bioreactors with Nitrate or Nitrite
Authors: Hubert Casey , Nemati Mehdi , Jenneman Gary , Voordouw Gerrit 
Published: April 2003

AbstractProduced water from the Coleville oil field in Saskatchewan, Canada was used to inoculate continuous up‐flow packed‐bed bioreactors. When 7.8 mM sulfate and 25 mM lactate were present in the in‐flowing medium, H2S production (souring) by sulfate‐reducing bacteria (SRB) was prevented by addition of 17.5 mM nitrate or 20 mM nitrite. Changing the sulfate or lactate concentration of the in‐flowing medium indicated that the concentrations of nitrate or nitrite required for containment of souring decreased proportionally with a lowered concentration of the electron donor lactate, while the sulfate concentration of the medium had no effect. Microbial communities were dominated by SRB. Nitrate addition did not give rise to changes in community composition, indicating that lactate oxidation and H2S removal were caused by the combined action of SRB and nitrate‐reducing, sulfide‐oxidizing bacteria (NR‐SOB). Apparently the nitrite concentrations formed by these NR‐SOB did not inhibit the SRB sufficiently to cause community shifts. In contrast, significant community shifts were observed upon direct addition of high concentrations (20 mM) of nitrite. Strains NO3A and NO2B, two newly isolated, nitrate‐reducing bacteria (NRB) emerged as major community members. These were found to belong to the ϵ‐division of the Proteobacteria, to be most closely related to Campylobacter lari, and to oxidize lactate with nitrate or nitrite as the electron acceptor. Thus the mechanism of microbial H2S removal in up‐flow packed‐bed bioreactors depended on whether nitrate (SRB/NR‐SOB) or nitrite (SRB/NR‐SOB as well as NRB) was used. However, the amount of nitrate or nitrite needed to completely remove H2S was dictated by the electron donor (lactate) concentration, irrespective of mechanism.
Asymmetric Synthesis with Immobilized Yeast in Organic Solvents: Equilibrium Conversion and Effect of Reactant Partitioning on Whole Cell Biocatalysis
Authors: Gervais Thomas R. , Carta Giorgio , Gainer John L. 
Published: April 2003

AbstractA newly isolated strain of the yeast Saccharomyces cerevisiae is investigated for the biocatalytic reduction of ketones and the oxidation of alcohols in organic solvents. The yeast cells are immobilized by entrapment within calcium alginate beads and are found to possess the ability to stereoselectively reduce prochiral ketones and oxidize chiral alcohols to equilibrium conversions. The effect of reactant partitioning on the initial rate of the reactions is also investigated. The observed initial rates are found to vary inversely with reactant partitioning between the organic solvent and the biocatalyst beads. A kinetic model is developed to describe the initial reaction rate of hexanone reduction as a function of substrate concentration within the alginate beads.
Oxidative Degradation of Azo Dyes by Manganese Peroxidase under Optimized Conditions
Authors: Mielgo I. , López C. , Moreira M. T. , Feijoo G. , Lema J. M. 
Published: April 2003

AbstractThe application of enzyme‐based systems in waste treatment is unusual, given that many drawbacks are derived from their use, including low efficiency, high costs and easy deactivation of the enzyme. The goal of this study is the development of a degradation system based on the use of the ligninolytic enzyme manganese peroxidase (MnP) for the degradation of azo dyes. The experimental work also includes the optimization of the process, with the objective of determining the influence of specific physicochemical factors, such as organic acids, H2O2 addition, Mn2+ concentration, pH, temperature, enzyme activity and dye concentration. A nearly total decolorization was possible at very low reaction times (10 min) and at high dye concentration (up to 1500 mg L−1). A specific oxidation capacity as high as 10 mg dye degraded per unit of MnP consumed was attained for a decolorization higher than 90%. Among all, the main factor affecting process efficiency was the strategy of H2O2 addition. The continuous addition at a controlled flow permitted the progressive participation of H2O2 in the catalytic cycle through a suitable regeneration of the oxidized form of the enzyme, which enhanced both the extent and the rate of decolorization. It was also found that, in this particular case, the presence of a chelating organic acid (e.g., malonic) was not required for an effective operation. Probably, Mn3+ was chelated by the dye itself. The simplicity and high efficiency of the process open an interesting possibility of using of MnP for solving other environmental problems.
Integration of Cell Culture and Microfabrication Technology
Authors: Park Tai Hyun , Shuler Michael L. 
Published: April 2003

AbstractRecent progress in cell culture and microfabrication technologies has contributed to the development of cell‐based biosensors for the functional characterization and detection of drugs, pathogens, toxicants, and odorants. The cell‐based biosensors are composed of two transducers, where the primary transducer is cellular and the secondary transducer is typically electrical. Advances in gene manipulation and cell culture techniques have contributed to the development of the cell as a transducer, while microfabrication techniques have been applied to the development of integrating the cell with the second transducer. Cellular patterning using microfabrication techniques is essential for cell‐based biosensors, cell culture analogues, tissue engineering, and fundamental studies of cell biology. The photolithographic technique is highly developed and has been widely used for patterning cells. Recently, a set of alternative techniques, largely based on soft lithoghraphy, has been developed for biological applications. Those techniques include microcontact printing, microfluidic patterning using microchannels, and laminar flow patterning. A classical metallic stencil patterning method has been improved by employing a rubber‐like stencil. These cellular micropatterning techniques have been usefully employed to understand questions in fundamental cell biology, especially cellular interactions with various materials and other cells. Using these micropatterning tecchniques and insights into the interaction of cellular biology with surfaces, a wide array of biosensors have been developed. In this manuscript examples of cell‐based biosensors are described. Neurons have a great potential for use in a cell‐based biosensor because they are electrically excitable cells, from which electrical signals are generated with the binding of detecting molecules. Consequently, the electrical signals generated in the cell can be determined in a noninvasive manner. A microphysiometer is a device to detect functional responses from cells by measuring the change of extracellular pH. The main application of the microphysiometer is the analysis of functional responses of cells upon receptor stimulation. Development of a microscale cell culture analogue system, an in vitro animal or human surrogate, is another promising area using cell culture and microfabrication technologies. Such devices are potentially very useful in the fields of toxicology and drug testing because they may increase the accuracy of in vitro predictions, simplify testing procedures, and reduce the cost of such tests, allowing many more tests to be done with a limited set of resources.
Effect of Reaction Parameters on Synthesis of Citronellyl Methacrylate by Lipase‐Catalyzed Transesterification
Authors: Athawale Vilas , Manjrekar Narendra , Athawale Manoj 
Published: April 2003

AbstractThe methacrylate ester of citronellol was synthesized using various lipases as catalyst. The effect of different reaction parameters such as amount of lipase, solvent, temperature, and acylating agent on the conversion of citronellol to citronellyl methacrylate was studied. Methyl methacrylate, vinyl methacrylate, and 2,3‐butanedione mono‐oxime methacrylate were used as acylating agents. Porcine pancreatic lipase (PPL), Candida rugosa lipase (CRL), and Pseudomonas cepacia lipase (Amano‐PS) were used as biocatalysts. Diisopropyl ether (DIPE) was found to be the most suitable solvent. The stereoselectivity of CRL in transesterification of (±)‐citronellol was tested for the optimized reaction parameters.
Hydrolysis of Proteins by Immobilized‐Stabilized Alcalase‐Glyoxyl Agarose
Authors: Tardioli Paulo W. , Pedroche Justo , Giordano Raquel L. C. , Fernández‐Lafuente Roberto , Guisán José M. 
Published: April 2003

AbstractThis paper presents stable Alcalase‐glyoxyl derivatives, to be used in the controlled hydrolysis of proteins. They were produced by immobilizing‐stabilizing Alcalase on cross‐linked 10% agarose beads, using low and high activation grades of the support and different immobilization times. The Alcalase glyoxyl derivatives were compared to other agarose derivatives, prepared using glutaraldehyde and CNBr as activation reactants. The performance of derivatives in the hydrolysis of casein was also tested. At pH 8.0 and 50 °C, Alcalase derivatives produced with 1 h of immobilization time on agarose activated with glutaraldehyde, CNBr, and low and high glyoxyl groups concentration presented half‐lives of ca. 10, 29, 60, and 164 h, respectively. More extensive immobilization monotonically led to higher stabilization. The most stabilized Alcalase‐glyoxyl derivative was produced using 96 h of immobilization time and high activation grade of the support. It presented half‐life of ca. 23 h, at pH 8.0 and 63 °C and was ca. 500‐fold more stable than the soluble enzyme. Thermal inactivation of all derivatives followed a single‐step non‐first‐order kinetics. The most stable derivative presented ca. 54% of the activity of the soluble enzyme for the hydrolysis of casein and of the small substrate Boc‐Ala‐ONp. This behavior suggests that the decrease in activity was due to enzyme distortion but not to wrong orientation. The hydrolysis degree of casein at 80 °C with the most stabilized enzyme was 2‐fold higher than that achieved using soluble enzyme, as a result of the thermal inactivation of the latter. Therefore, the high stability of the new Alcalase‐glyoxyl derivative allows the design of continuous processes to hydrolyze proteins at temperatures that avoid microbial growth.
Yeast Metallothionein in Transgenic Tobacco Promotes Copper Uptake from Contaminated Soils
Authors: Thomas John C. , Davies Elizabeth C. , Malick Farah K. , Endreszl Charles , Williams Chandra R. , Abbas Mohammed , Petrella Sally , Swisher Krystal , Perron Mike , Edwards Ryan , Ostenkowski Pam , Urbanczyk Nicolas , Wiesend Wendy N. , Murray Kent S. 
Published: April 2003

AbstractMetallothioneins (MTs) are metal‐binding proteins that confer heavy metal tolerance and accumulation in yeast. To augment higher plant metal sequestration, the yeast metallothionein (CUP 1) was introduced into tobacco plants. The CUP 1 gene expression and copper and cadmium phytoextraction were determined. To confirm transformation, selfed and kanamycin‐resistant third generation plants were subjected to DNA blot and polymerase chain reaction (PCR) analysis. A 4 mM CuSO4 stress for 7 days resulted in a decline in CUP 1 transcripts versus nonstress conditions. Despite low mRNA levels, CUP 1 transformants accumulated up to seven times more copper in older versus younger leaves during copper stress. Pooled leaves of transgenic plants grown in soils from copper stamp‐sands contained two to three times the copper content as that of the control plants. Unlike some previous reports featuring MT overexpression in plants, CUP 1 seedlings did not significantly sequester or demonstrate tolerance to CdCl2. Using this transgenic approach, yeast CUP 1 expression under nonstressed conditions contributed to copper metal phytoextraction during a subsequent copper challenge. This strategy could be incorporated into plants designed for enhanced phytoremediation of metal contaminants.
Fed‐Batch Cultivation of Saccharomyces cerevisiae in a Hyperbaric Bioreactor
Authors: Belo I. , Pinheiro R. , Mota M. 
Published: April 2003

AbstractFed‐batch is the dominating mode of operation in high‐cell‐density cultures of Saccharomyces cerevisaein processes such as the production of bakerapos;s yeast and recombinant proteins, where the high oxygen demand of these cultures makes its supply an important and difficult task. The aim of this work was to study the use of hyperbaric air for oxygen mass transfer improvement on S. cerevisiaefed‐batch cultivation. The effects of increased air pressure up to 1.5 MPa on cell behavior were investigated. The effects of oxygen and carbon dioxide were dissociated from the effects of total pressure by the use of pure oxygen and gas mixtures enriched with CO2. Fed‐batch experiments were performed in a stirred tank reactor with a 600 mL stainless steel vessel. An exponential feeding profile at dilution rates up to 0.1 h−1 was used in order to ensure a subcritical flux of substrate and, consequently, to prevent ethanol formation due to glucose excess. The ethanol production observed at atmospheric pressure was reduced by the bioreactor pressurization up to 1.0 MPa. The maximum biomass yield, 0.5 g g−1 (cell mass produced per mass of glucose consumed) was attained whenever pressure was increased gradually through time. This demonstrates the adaptive behavior of the cells to the hyperbaric conditions. This work proved that hyperbaric air up to 1.0 MPa (0.2 MPa of oxygen partial pressure) could be applied to S. cerevisiaecultivation under low glucose flux. Above that critical oxygen partial pressure value, i.e., for oxygen pressures of 0.32 and 0.5 MPa, a drastic cell growth inhibition and viability loss were observed. The increase of carbon dioxide partial pressure in the gas mixture up to 48 kPa slightly decreased the overall cell mass yield but had negligible effects on cell viability.
Continuation of Pregnancy Following the Diagnosis of a Fetal Sex Chromosome Abnormality: A Study of Parents' Counseling Needs and Experiences
Authors: Petrucelli Nancie , Walker Martha , Schorry Elizabeth 
Published: April 2003

AbstractParents who decide to continue a pregnancy diagnosed with a sex chromosome abnormality (SCA) experience a variety of emotions as they deal with complex medical and genetic information. To better understand these individuals' psychosocial, educational, and support needs, 26 parents who received prenatal diagnosis of an SCA after 1989 and who had decided to continue their pregnancy were interviewed by telephone. Twenty (77%) reported they initially had a “poor” understanding of the predicted syndrome. All parents later met with a genetics professional. Twenty‐two (92%) parents considered sterility and underdevelopment of secondary sexual characteristics to be the most negative aspects of SCAs. Contact with other parents of children with SCAs and with support organizations were generally viewed as helpful experiences. Insight gained from this study should be useful for genetic counselors and other health care providers involved with patients who have received abnormal prenatal diagnosis results.
Attitudes Toward Cystic Fibrosis Carrier and Prenatal Testing and Utilization of Carrier Testing Among Relatives of Individuals with Cystic Fibrosis
Authors: Lafayette DeeDee , Abuelo Dianne , Passero Mary Ann , Tantravahi Umadevi 
Published: April 2003

AbstractA questionnaire and an offer of free carrier testing was mailed to 173 relatives of individuals with CF. The questionnaire addressed their knowledge of clinical and genetic aspects of CF, as well as their attitudes toward carrier testing, prenatal diagnosis, and pregnancy termination for CF. Eighty‐one individuals returned the questionnaire (47%) and 50 elected carrier testing (29%). Most respondents underestimated their carrier risk (60%), but overestimated their risk to have a child with CF (63%). Most (93%) indicated they would utilize carrier testing, and 70% would use prenatal testing; however, only 7% would consider terminating a pregnancy for CF. The intention to use prenatal testing was correlated with the perceived health of the proband and whether the respondent was planning to have (more) children. The acceptability of abortion was correlated with the respondent's perceived impact or burden of CF.
The Risk and Protective Functions of Perceived Family and Peer Microsystems Among Urban Adolescents in Poverty
Authors: Seidman Edward , Chesir-Teran Daniel , Friedman Jennifer L. , Yoshikawa Hirokazu , Allen LaRue , Roberts Ann , Aber J. Lawrence 
Published: April 2003

AbstractUtilized a pattern‐based approach to discover the different constellations of perceived social transactions separately for family and peer systems and explored the risk and protective functions of these microsystem profiles for both depression and antisocial behavior among a sample of ethnically and racially diverse urban adolescents living in poverty. Measures of perceived social support, involvement and hassles with family and peers, as well as perceived social acceptance and peers' values were entered into two sets of iterative cluster analyses to identify distinct profiles of family and peer transactions. From each of the perceived family and peer transactional analyses, six replicated profiles emerged. Several of the profiles were consistent with expectations from prior literature such as Enmeshing families and Rejecting peer networks, while others were novel and intriguing such as Entangling peers. Family profiles were consistent in their risk and protective associations for both depression and antisocial behavior, while the peer profiles varied in their effects for each developmental outcome. For example, the Rejecting peer profile placed adolescents at increased risk for depression but protected them from antisocial behavior. Implications for future research and preventive intervention are discussed.
Assessing experiences and responses of crime victims
Authors: Carlson Eve B. , Dutton Mary Ann 
Published: April 2003

AbstractThis paper reviews strategies and methods for assessing crime victims with an emphasis on assessments for clinical purposes. In terms of outcomes, this paper primarily focuses on assessing posttraumatic symptoms of PTSD, dissociation, and traumatic grief as these are all quite disabling and may be mediators of other responses. Additional topics reviewed include reasons to assess experiences and responses of crime victims, issues to bear in mind when conducting assessments for different purposes, considerations for use of various sources of information about a client, characteristics of measures and of clinents to take into account when selecting measures, recommended domains of experiences and symptoms to assess, and suggestions about the process of administering measures and conducting therapeutic assessments.
Development of the Critical Elements of Genetic Evaluation and Genetic Counseling for Genetic Professionals and Perinatologists in Washington State
Authors: Marymee Kathi , Dolan Cynthia R. , Pagon Roberta A. , Bennett Robin L. , Coe Sandra , Fisher Nancy L. 
Published: April 2003

AbstractWe present a method for the development of consensus documents describing the components of genetic evaluation and genetic counseling for various diagnoses. These documents were developed to encourage consistency among genetic professionals in Washington State. Other possible uses of these documents are to provide information regarding genetic evaluations for health care practitioners and payers, and to assist in quality assurance and genetic training programs. A working group of six genetic professionals developed two templates for the “critical elements of genetic evaluation and genetic counseling,” for clinical (nonprenatal) and prenatal patients. The working group then completed prototype templates for several specific genetic disorders. The templates and prototypes were sent to interested genetic professionals and perinatologists who submitted a total of 76 draft “critical elements” (CE's) to the working group. At two statewide meetings, participating practitioners modified and unanimously approved the CE templates, then unanimously approved the 21 draft CEs that had been finalized in small group discussions. Approved CE's were distributed to genetic professionals and perinatologists within the state.