bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear dynamical law governs magnetic field induced changes in lymphoid phenotype
Authors: Marino Andrew A. , Wolcott R. Michael , Chervenak Robert , Jourd'heuil Frances , Nilsen Erik , Frilot Clifton 
Published: August 2002

AbstractThe results of many different types of animal and human studies dealing with the biological effects of exposure to low frequency electromagnetic fields (EMFs) have consistently been both positive and negative. We addressed the question of why this pattern had occurred so commonly in biological studies involving exposure to EMFs and hypothesized that it stemmed from the prevalent use of a linear model to characterize what are inherently nonlinear input–output relationships. The hypothesis was tested by analyzing biological data using a novel statistical procedure that could be adjusted to detect either nonlinear or linear effects. The reliability of the procedure was established using positive and negative controls and by comparison with the results obtained from sampling a known nonlinear system. In four independent experiments, male and female mice were exposed continuously to 0.1 or 0.5 mT, 60 Hz, for 175 days, and the effect on 20 immune parameters was measured using flow cytometry and functional assays. In each experiment, EMF exposure resulted in statistically significant changes in lymphoid phenotype when and only when the response of the animals to the fields was analyzed as if it were governed by nonlinear laws. Our results suggest that the pattern of inconsistency in the EMF bioeffects studies is an artifact resulting from an incorrect choice of the conceptual model for the relation between the field and the biological effect it causally determines. Bioelectromagnetics 22:529–546, 2001. © 2001 Wiley‐Liss, Inc.
Digging for innate immunity since Darwin and Metchnikoff
Authors: Cooper Edwin L. , Kauschke Ellen , Cossarizza Andrea 
Published: August 2002

AbstractImmune systems are, increasingly, being studied from comparative perspectives. The analysis of the immunedefense systems of invertebrates, such as fruit flies and earthworms, is an important part of this effort. These systems are innate, natural non‐specific, non‐anticipatory and non‐clonal. This is in contrast to the macrophage T and B systems that characterize vertebrate adaptive immunity whose properties can be categorized as adaptive, induced, specific, anticipatory, and clonal. In this review, we will focus on the earthworm system. Earthworms, like other complex invertebrates, possess several leukocyte types and synthesize and secrete a variety of immunoprotective molecules. The system as a whole effects phagocytosis, encapsulation, agglutination, opsonization, clotting and lysis of foreign components. At least two major leukocytes, small coelomocytes, and large coelomocytes mediate lytic reactions against several targets. Destruction of tumor cells in vitro shows that phagocytosis and natural killer cell responses are distinct properties of coelomocytes. A third type, the chlorogogen cell, synthesizes and sheds effector lytic molecules. Among the lytic molecules, three have been identified and sequenced (fetidins, CCF‐1, lysenin) and another has been discovered (eiseniapore), while three other molecules, H1 H2 H3, share agglutinating and lysing functions. In contrast to these, Lumbricin I is the only known molecule of the earthworm system that is antimicrobial but non‐lytic. Altogether the cellular and humoral components of the earthworm system function to distinguish between self and not self, dispose of internal (cancer?), damaged components and external antigens (microbes). The evolutionary context of the earthworm innate immune system is discussed at the end of this article. BioEssays 24:319–333, 2002. ©2002 Wiley Periodicals, Inc.
Minimally disturbed, multicycle, and reproducible synchrony using a eukaryotic “baby machine”
Authors: Cooper Stephen 
Published: August 2002

AbstractA eukaryotic “baby machine” has been developed that produces synchronized cultures that display up to four synchronous cell cycles. 1 That such cells can be produced implies that methods unable to produce successive synchronized cell cycles may not actually synchronize cells. But most important, the baby machine method now opens the way for the study of the cell cycle of minimally disturbed, artifact‐free, well‐synchronized, mammalian cells. BioEssays 24:499–501, 2002. © 2002 Wiley Periodicals, Inc.
Decisive factors: a transcription activator can overcome heterochromatin silencing
Authors: Eissenberg Joel C. 
Published: August 2002

AbstractEukaryotes organize certain chromosomal intervals into domains capable of si lencing most genes. Examples of silencing domains include the HML/HMR loci and subtelomeric chromatin in yeast, the Barr body X chromosome in mammals, and the pericentric heterochromatin of Drosophila. Silencing chromatin is often correlated with more regularized nucleosomal array than that found in active chromatin, and transcriptional activators appear to be missing from their target sites in silent chromatin. In Drosophila, gene silencing by heterochromatin is often variegated, indicating that a gene may escape silencing in some cells. In a recent study, Ahmad and Henikoff(1) show that a yeast activator can compete successfully with Drosophila heterochromatic silencing factors for target sites in DNA. This competition, together with developmental change in the stability of heterochromatin itself, decides the transcriptional state for a gene subject to heterochromatin repression. BioEssays 23:767–771, 2001. © 2001 John Wiley & Sons, Inc.
Functional analysis of self‐injury maintained by automatic reinforcement: exposing masked social functions
Authors: McKerchar Todd L. , Kahng SungWoo , Casioppo Elyse , Wilson David 
Published: August 2002

AbstractTwo functional analyses for self‐injurious behavior (SIB) exhibited by a child diagnosed with mental retardation and autism were conducted. Responding was high and undifferentiated in the first functional analysis, indicating that SIB was maintained by automatic reinforcement. During the second functional analysis, the client wore a padded helmet and all SIB was blocked. SIB decreased in all conditions except attention, suggesting that SIB was multiply controlled (social positive and automatic reinforcement). Copyright © 2001 John Wiley & Sons, Ltd.
On residues in the disallowed region of the Ramachandran map
Authors: Pal Debnath , Chakrabarti Pinak 
Published: August 2002

AbstractAn analysis of the occurrence of nonglycyl residues in conformations disallowed in the Ramachandran plot is presented. Ser, Asn, Thr, and Cys have the highest propensities to exhibit such conformations, and the branched aliphatic residues the lowest. Residues cluster in five regions and there are some trends in the types of residues and their side‐chain conformations (χ1) occupying these. Majority of the residues are found at the edge of helices and strands and in short loops, and are involved in different types of weak, stabilizing interactions. A structural motif has been identified where a residue in disallowed conformation occurs as the first residue of a short 310‐helix. On the basis of the types of neighboring residues, the location in the three‐dimensional structure and accessibility, there are similarities with the occurrence of cis peptide bonds in protein structures. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 195–206, 2002; DOI 10.1002/bip.10051
Mutation of residues critical for benzohydroxamic acid binding to horseradish peroxidase isoenzyme C
Authors: Howes Barry D. , Heering Hendrik A. , Roberts Thomas O. , Schneider‐Belhadadd Florence , Smith Andrew T. , Smulevich Giulietta 
Published: August 2002

AbstractAromatic substrate binding to peroxidases is mediated through hydrophobic and hydrogen bonding interactions between residues on the distal side of the heme and the substrate molecule. The effects of perturbing these interactions are investigated by an electronic absorption and resonance Raman study of benzohydroxamic acid (BHA) binding to a series of mutants of horseradish peroxidase isoenzyme C (HRPC). In particular, the Phe179 → Ala, His42 → Glu variants and the double mutant His42 → Glu:Arg38 → Leu are studied in their ferric state at pH 7 with and without BHA. A comparison of the data with those previously reported for wild‐type HRPC and other distal site mutants reaffirms that in the resting state mutation of His42 leads to an increase of 6‐coordinate aquo heme forms at the expense of the 5‐coordinate heme state, which is the dominant species in wild‐type HRPC. The His42Glu:Arg38Leu double mutant displays an enhanced proportion of the pentacoordinate heme state, similar to the single Arg38Leu mutant. The heme spin states are insensitive to mutation of the Phe179 residue. The BHA complexes of all mutants are found to have a greater amount of unbound form compared to the wild‐type HRPC complex. It is apparent from the spectral changes induced on complexation with BHA that, although Phe179 provides an important hydrophobic interaction with BHA, the hydrogen bonds formed between His42 and, in particular, Arg38 and BHA assume a more critical role in the binding of BHA to the resting state. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 261–267, 2001
Effect of water activity and immobilization on fatty acid selectivity for esterification reactions mediated by lipases
Authors: Lee Chen‐Hsien , Parkin Kirk L. 
Published: August 2002

AbstractThe effect of water activity (aw) and immobilization on fatty acid (FA) selectivity of Burkholderia (formerly Pseudomonas) cepacia, Rhizomucor miehei, Candida antarctica (type B), and Candida rugosa lipases in esterification reactions was determined. Studies were based on measuring ester formation in multicompetitive reaction mixtures containing either the homologous series of even carbon number n‐chain saturated FA (C4‐C18) or a series of n‐chain (un)saturated FA (C18:X, where X = 0–3 double bonds) as cosubstrates with 1,3‐propanediol in ter‐butyl methyl ether at aw of 0.19, 0.69, and 0.90. Activity and FA selectively patterns were similar for free and Celite‐adsorbed lipases in response to changes in aw, although specific effects were observed for selectivity of B. cepacia and C. rugosa lipases toward C16 and C4/C6 FA, respectively. Also, selectivity toward unsaturated C18:X FA as a group was modulated by changes in aw for three of the four lipase studied. Resin‐fixed lipases from R. miehei and C. antarctica exhibited profound differences in activity and FA selectively in response to changes in aw, relative to free and Celite‐bound forms. These findings suggest that FA selectivity for lipid modification is influenced by aw and immobilization, but that each lipase has a characteristic response to these factors in a manner that cannot be predicted. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 219–227, 2001.
Effects and mechanisms of H2O2 on production of dicarboxylic acid
Authors: Jiao Peng , Huang Yingming , Li Shuliang , Hua Yutao , Cao Zhu'an 
Published: August 2002

AbstractThe system of producing long chain dicarboxylic acid (DCA) by Candida tropicalis is an aerobic and viscous fermentation system. A method to overcome the gas‐liquid transport resistance and to increase oxygen supply is by adding hydrogen peroxide (H2O2) to the fermentation system. Here we report that the H2O2 not only can enhance the oxygen supply but also change the metabolism by inducing cytochrome P450, the key enzyme of a, o‐oxidation. When C. tropicalis was cultivated in a 3‐L bioreactor using the combination of aeration and H2O2 feeding, DCA production rates increased by about 10% after a short period of decrease at the beginning. Furthermore, the experiments showed that the maximum activities of P450 could be induced at 2 mM H2O2, and the inducible mechanisms are also discussed. Moreover, we suggest that alkane might be oxidized through the “peroxide shunt pathway” when H2O2 is present. By adding H2O2, the DCA yield in a 22‐L bioreactor could increase by 25.3% and reach 153.9 g/L. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 456–462, 2001.
Extracellular production of biologically active deacetoxycephalosporin C synthase from Streptomyces clavuligerus in Pichia pastoris
Authors: Adrio José L. , Velasco Javier , Soler Gloria , Saiz Marta Rodriguez , Barredo José L. , Moreno Miguel A. 
Published: August 2002

AbstractWe have successfully expressed and observed secretion of the Streptomyces clavuligerus deacetoxycephalosporin C synthase (DAOCS) using the Pichia pastoris expression system. Two clones having multiple copies of the expression cassette were selected and used for protein‐expression analysis. SDS‐PAGE showed efficient expression and secretion of the bacterial recombinant DAOCS. The highest yield (120 μg/mL) was obtained when expression was induced with 2% methanol. Free and immobilized protein were assayed for biological activity and found to expand penicillin N (its natural substrate) and penicillin G to deacetoxycephalosporin C (DAOC) and deacetoxycephalosporin G (DAOG), respectively. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 485–491, 2001.
Quorum signaling via AI‐2 communicates the “Metabolic Burden” associated with heterologous protein production in Escherichia coli
Authors: DeLisa Matthew P. , Valdes James J. , Bentley William E. 
Published: August 2002

AbstractRecent reports have shown that bacterial cell–cell communication or quorum sensing is quite prevalent in pathogenic Escherichia coli, especially at high cell density; however, the role of quorum sensing in nonpathogenic E. coli is less clear and, in particular, there is no information regarding the role of quorum sensing in overexpression of plasmid‐encoded genes. In this work, it was found that the activity of a quorum signaling molecule, autoinducer‐2 (AI‐2), decreased significantly following induction of several plasmid‐encoded genes in both low and high‐cell‐density cultures of E. coli. Furthermore, we show that AI‐2 signaling level was linearly related to the accumulation level of each protein product and that, in general, the highest rates of recombinant protein accumulation resulted in the greatest attenuation of AI‐2 signaling. Importantly, our findings demonstrate for the first time that recombinant E. coli communicate the stress or burden of overexpressing heterologous genes through the quorum‐based AI‐2 signaling pathway. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 439–450, 2001.
Pore‐scale investigation of biomass plug development and propagation in porous media
Authors: Stewart Terri L. , Scott Fogler H. 
Published: August 2002

AbstractBiomass plugging of porous media finds application in enhanced oil recovery and bioremediation. An understanding of biomass plugging of porous media was sought by using a porous glass micromodel through which biomass and nutrient were passed. This study describes the pore‐scale physics of biomass plug propagation of Leuconostoc mesenteroides under nutrient‐rich conditions. It was found that, as the nutrient flowed through the micromodel, the initial biomass plug occurred at the nutrient–inoculum interface due to growth in the larger pore throats. As growth proceeded, biomass filled and closed these larger pore throats, until only isolated groupings of pore throats with smaller radii remained empty. As nutrient flow continued, a maximum pressure drop was reached. At the maximum pressure drop, the biomass yielded in a manner similar to a Bingham plastic to form a breakthrough channel consisting of a path of interconnected pore throats. The channel incorporated the isolated groupings of empty pore throats that had been present before breakthrough. As the nutrient flow continued, subsequent plugs developed as breakthrough channels refilled with biomass and in situ growth was stimulated in the region just downstream of the previous plug. The downstream plugs had a higher fraction of isolated groupings of empty pore throats, which can be attributed to depletion of nutrient downstream. When the next breakthrough channel formed, it incorporated these isolated groupings, causing the breakthrough channels to be branched. It was observed that the newly formed plug could be less stable with this higher fraction of empty pore throats and that the location of breakthrough channels changed in subsequent plugs. This change in breakthrough channel location could be attributed to the redistribution of nutrient flow and the changes in flowrate in the pore throats. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 577–588, 2002; DOI 10.1002/bit.10044
A simple method to release polyphosphate from activated sludge for phosphorus reuse and recycling
Authors: Kuroda Akio , Takiguchi Noboru , Gotanda Takafumi , Nomura Kazutaka , Kato Junichi , Ikeda Tsukasa , Ohtake Hisao 
Published: August 2002

AbstractIn enhanced biological phosphorus removal processes, activated sludge microorganisms accumulate large quantities of polyphosphate (polyP). It was discovered that nearly all of the polyP could be released from activated sludge simply by heating it at 70°C for about 1 h. The chain length of released polyP ranged from 100 to 200 phosphate (Pi) residues. The addition of CaCl2 precipitated approximately 75% of the total phosphorus without pH adjustment. The formed precipitate contained more P and less Ca than typical natural phosphorite deposits. Hence, in combination with enhanced biological phosphorus removal, the present method has potential for the development of a simple process for recovering phosphorus in a reusable form from wastewater. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 333–338, 2002.
A strategy for in vivo screening of subtilisin E reaction specificity in E. coli periplasm
Authors: Sroga Grazyna E. , Dordick Jonathan S. 
Published: August 2002

AbstractWe developed a protocol for efficient expression of the functional serine protease, subtilisin E, in Escherichia coli periplasm that permits direct in vivo measurement of the enzyme's catalytic activity. Activity assays and SDS‐PAGE/Western blot analysis showed that the levels of expressed subtilisin varied and were correlated with both the culture conditions and the induction procedures. The highest level of subtilisin expression was achieved at 0.10–0.15% (w/v) of arabinose as inducer and a temperature of 20–22°C, and was ca. eightfold higher as compared to the expression level at 30°C. Cultivation of bacterial cells to a steady state of balanced growth before induction was required for uniform subtilisin expression in cell cultures growing in wells of microtiter plates. Amidase and esterase cell‐based kinetic assays on microtiter plates were developed based on the direct measurement of subtilisin activity in vivo. Intact E. coli cells displaying wild‐type, dimethylformamide‐resistant, and temperature‐resistant subtilisins were assayed on N‐succinyl‐Ala‐Ala‐Pro‐Phe‐p‐nitroanilide and N‐acetyl‐Phe‐p‐nitrophenyl ester for their amidase and esterase activity, respectively. Additionally, the periplasmic fractions were isolated from the three E. coli strains expressing the respective subtilisins and tested for amidase activity. The amidase activity of the three subtilisins was ca. 15‐fold higher than the esterolytic activity when measured in both the intact cells and in the periplasmic fractions. The strategy combining periplasmic expression of subtilisins with two cell‐based kinetic assays permits rapid screening of subtilisin mutant libraries for desired activities. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 761–769, 2002.
Long‐term performance of bioreactors cleaning mercury‐contaminated wastewater and their response to temperature and mercury stress and mechanical perturbation
Authors: von Canstein H. , Li Y. , Wagner‐Döbler I. 
Published: August 2002

AbstractThe long‐term performance of bioreactors retaining mercury from contaminated industrial wastewater was analyzed at the laboratory scale, and its response to mechanical perturbations (gas bubbles and shaking) as well as to physical (increased temperature and hydraulic load) and chemical stresses (increased mercury concentration) likely to occur during on site operation was studied. Two packed‐bed bioreactors with 80‐cm3 lava chips as biofilm carrier were inoculated with nine Hg(II)‐resistant natural isolates of α‐ and γ‐proteobacteria. Chloralkali wastewater containing ionic mercury (3.0 to 9.7 mg/L Hg2+), amended with sucrose and yeast extract, flowed through the bioreactors at 160 mL/h. During the 16‐month investigation the bioreactors showed no sign of depleted performance in terms of mercury‐retaining capacity. After 16 months, both bioreactors still retained 96% of the mercury load. The performance of the bioreactors was sensitive to mechanical perturbations (e.g., sheer forces of gas bubbles). Shifts to higher Hg2+ inflow concentrations initially decreased the mercury retention efficacy slightly. However, the bioreactors could adapt to Hg2+ concentrations of up to 7.6 mg/L within several days. Old biofilms were less affected than the younger ones. The performance of the bioreactors was not affected by an increase in temperature up to 41°C and an increased volumetric load (up to 240 mL/h). The bioreactors regained activity spontaneously after the stress had stopped. Recovery could be accelerated by increased nutrient concentration, although this may lead to blocking of the packed bed. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 212–219, 2001.
Sensitive and simultaneous determination of HIV protease inhibitors in rat biological samples by liquid chromatography–mass spectrometry
Authors: Gao Weihua , Kishida Tomoyuki , Kimura Keisuke , Kageyama Michiharu , Sumi Masaki , Yoshikawa Yukako , Shibata Nobuhito , Takada Kanji 
Published: August 2002

AbstractA sensitive and simultaneous liquid chromatographic–mass spectrometric (LC/MS) method for the determination of current four HIV protease inhibitors (PIs), indinavir (IDV), saquinavir (SQV), nelfinavir (NFV) and amprenavir (APV) in rat plasma and liver dialysate by a microdialysis method was described. An isocratic LC/MS method in combination with atmospheric pressure chemical ionization was developed for the determination of these four PIs in biological samples in the same run. The analytes including an internal standard were extracted from 100 µL of plasma or 150 µL of liver dialysate samples by salting‐out with 100 µL of ice‐cold 2 M K3PO4 followed by ether extraction. The separation of analytes was carried out on a reversed‐phase semi‐micro column using 50% of acetonitrile containing 1% acetic acid as mobile phase at a flow rate of 0.2mL/min−1. The separation was completed within 5 min. Precision, recovery and limits of detection indicated that the method was suitable for the quantitative determination of these PIs in rat plasma or liver dialysate. This simple, sensitive and highly specific LC/MS method is suitable for pharmacokinetic studies and therapeutic drug monitoring in AIDS patients who receive double protease therapy. Copyright © 2002 John Wiley & Sons, Ltd.