bluuebunny/crossref_metadata_2025 huggingface dataset:
Propene polymerization with a magnesium chloride‐supported ziegler catalyst, 1. Principal kinetics
Authors: Keii Tominaga , Suzuki Eiichi , Tamura Masanori , Murata Masahide , Doi Yoshiharu
Published: April 2003

The main kinetic behavior of the slurry polymerization of propene with a MgCl2‐supported TiCl4/C6H5COOC2H5 catalyst, activated by Al(C2H5)3, was studied, Examination of the dependence of the polymerization rate on temperature and concentrations of Al(C2H5)3 and of propene resulted in a Langmuir‐Hinshelwood rate law with the number of polymerization centers dependent on time. The Polymerization rate as function of the polymerization temperature shows a maximum, which is compatible with the rate law. The analysis of the phenomenon of an optimum temperature gave 15 KJ. mol−1 and 36 KJ. Mol −1 for the activation energy of the rate determining step and the adsorption energy of Al(C2H5)3, respectively. Examination of the rapid decay of the polymerization rate showed that the main part of the decay is represented by a second order decay independent of the amount of polymer produced, which can be understood by a second order decay of surface sites by Al(C2H5)3. The number of active centers of the catalyst in gas phase polymerization was estimated applying the inhibition method with carbon monoxide. The results show a constant value for the propagation rate constant, Kp, during the second order rate decay. The observed polymerization kinetics strongly suggest the existence of two kinds of polymerization centers (isotactic and atactic).
Synthesis and phase behaviour of liquid crystalline polyacrylates
Authors: Portugall Michael , Ringsdorf Helmut , Zentel Rudolf
Published: April 2003

The synthesis and phase behaviour of a series of polymers having liquid crystalline sidechains and a poly(acrylic acid) backbone are described. These polymers show a dependence of the phase transition temperatures on molecular weight. In copolymers of two liquid crystalline acrylic esters, induced smectic phases occur. A comparison of the phase transitions of the different polyacrylates, with those of liquid crystalline polymethacrylates and polysiloxanes, published elsewhere, establishes that the spacer group achieves partial “decoupling” of liquid crystalline and polymer properties.
The influence of molecular interaction on polymerization, 7. Copolymerization of monomethyl itaconate with styrene
Authors: Boudevska Hrissanta , Platchkova Svetla , Todorova Olga
Published: April 2003

The copolymerization of monomethyl intaconate (MMI) with styrene (St) initiated with 2,2′‐azoisobutyronitrile in solvents differing in dielectric constants and capability to form hydrogen bonds was investigated. The IR‐ and 1H NMR spectroscopic studies of the monomer mixtures in four solvents have shown an influence of the solvent on the formation of hydrogen bonds and of other donor‐acceptor associates. The reactivity ratios of the monomer pairs in the different solvents are as follows: in chloroform, rMMI = 0,09 ± 0,05 and rSt = 0,14 ± 0,00; in acetonitrile, rMMI = 0,26 ± 0,10 and rSt = 0,36 ± 0,01; in dioxane, rMMI = 0,28 ± 0,01 and rSt = 0,55 ± 0,00; in acetone: rMMI = 0,18 ± 0,05 and rSt = 0,49 ± 0,00. The changes in the values of the reactivity ratios are connected with the ability of the solvents to govern the formation of hydrogen bonds among the MMI molecules and between the MMI and the solvent on the one hand and the formation of donor‐acceptor associates between both monomer molecules on the other. The increase of the concentration of associated monomer molecules which occur in chloroform leads to a decrease of the r‐values.
Polymer‐supported dinitrogen complexes of manganese. Coordination of molecular nitrogen in solid‐gas phase reaction under mild conditions
Authors: Kurimura Yoshimi , Ohta Fumihiko , Gohda Junko , Nishide Hiroyuki , Tsuchida Eishun
Published: April 2003

A copolymer (PC‐1) was synthesized from a mixture of 1,2‐and 1,3‐isomers of tricarbonyl‐(methylvinylcyclopentadienyl)manganese (1) and styrene (St) crosslinked with 1,4‐divinylbenzene, and a membrane (PM–1) consisting of the 1/St copolymer. A polymer‐supported dinitrogen complex (PC‐4) was prepared from the tetrahydrofuran (THF) complex of PC‐1 and molecular nitrogen in a solid‐gas phase reaction under moderate conditions. The dinitrogen complex membrane (PM–4) was readily obtained directly from PM‐1 by a “one‐step reaction” on UV light irradiation under normal pressure of nitrogen at room temperature. A prominent feature of polymer‐supported dinitrogen complexes, PC‐4 and PM‐4, is their high stability as compared with the corresponding low molecular weight analogues. The coordinated nitrogen can be substituted by carbon monoxide in a PC‐4/THF mixture. The mechanism of nitrogen co‐ordination to PC‐1 and PM‐1 was investigated by means of IR and/or absorption spectrometry.
Synthese und charakterisierung von linearem poly(iminoethylen)
Authors: Bartulín Juan , Rivas Bernabé Luis , Rodríguez‐Baeza Mario , Angne Ursula
Published: April 2003

Linear poly(iminoethylene) was synthetised by cationic polymerization of 2‐methyl‐2‐oxazoline using BF3O(C2H5)2, SnCl4, and CH3COBF4 as initiators and in the presence or absence of CH3CN. The resulting product, poly(N‐acetyliminoethylene), was then hydrolysed in basic medium. The resulting poly(iminoethylene) was identified and characterized by 1H NMR, 13C NMR, X‐ray diffraction, and differential scanning calorimetry (DSC). The synthetised polymer will be used as a polymeric support in ionic‐exchange resins as well as in macromolecular pesticides.
Polymerization of isobutene by the inifer technique, 1. Low molecular weight products using 1,4‐bis(1‐chloro‐1‐methylethyl)benzene/BCl3 as initiator
Authors: Nuyken Oskar , Pask Stephen D. , Vischer Axel
Published: April 2003

The cationic polymerization of isobutene by the “inifer”‐technique was studied. Preliminary experiments are described which suggest that useful polymer can be prepared only when BCl3 is rapidly added to the premixed monomer/inifer mixture and that such polymerizations do not go to completion. Some questions regarding the mechanism are discussed and remain open.
Grafting of N‐vinylpyrrolidone onto segmented polyurethane initiated by 2,2′‐azoisobutyronitrile
Authors: Egboh Sunday H. , George Maurice H. , Barrie James A. , Walsh David J.
Published: April 2003

An unsaturated segmented polyurethane was prepared from cis‐2‐butene‐1,4‐diol, poly(ethylene glycol), butane‐1,4‐diol, and methylene bis(4‐phenyl isocyanate). Graft copolymerization of N‐vinylpyrrolidone onto the segmented polyurethane was studied using 2,2′‐azoisobutyronitrile (AIBN) as initiator in DMF as solvent. The graft copolymers were isolated from the homopolymer and the ungrafted polyurethane by selective solvent extraction. The effect of reaction time, temperature, and of monomer and initiator concentrations on the degree of grafting was also investigated. The percent grafting was enhanced with increasing [AIBN] up to 40 mmol.dm‐3, but then decreased at higher concentrations. An explanation based on complex formation between the monomer and the urethane linkages in polyurethane is suggested.
Models and mechanism of the formation of poly(thio‐1,4‐phenylene)
Authors: Koch Wolfgang , Heitz Walter
Published: April 2003

The formation of poly(thio‐1,4‐phenylene) does not proceed by a normal polycondensation process. The mechanism was found to be a one‐electron‐transfer process with radical‐cations as reactive intermediates. This mechanism explains the formation of disulfides as side products. It could be shown in a model reaction that more than 20% of the disulfide can be formed in the early stage of the reaction and that the formation of disulfide is a reversible reaction, which explains the decrease of its content with the reaction time. Oligomers up to the octamer were prepared in a stepwise synthesis. The melting point and the enthalpy of melting of poly(thio‐1,4‐phenylene), crystallized as extended chains, were extrapolated from the melting points of the oligomers. From the UV spectra it could be deduced that the length of conjugated segments in solution is low.
Polymerization of ethylene oxide catalyzed by triphenylstibine oxide
Authors: Nomura Ryoki , Shiomura Yasuro , Ninagawa Akira , Matsuda Haruo
Published: April 2003

Polymerization of ethylene oxide (EO) and propylene oxide (PO) catalyzed by two types of triphenylstibine oxide ((C6H5)3SbO, TPSO) was investigated. The polymeric and high melting point triphenylstibine oxide (TPSOa) was found to be active, but it shows a long induction period in the polymerization at 80°C. During the induction period, TPSOa is probably cleaved into an active antimony species by interaction with EO. TPSOa is activated by addition of some O‐containing compounds such as ethanol, 1,4‐dioxane, or water. Monomeric and low melting point triphenylstibine oxides (TPSOb and TPSOc) were found to be inactive. Their activity markedly increases by addition of Lewis bases such as triphenylphosphine. The difference in the activity of TPSOa and TPSOb or TPSOc is considered to result from differences in aggregation.
Vinyl polymers with aromatic substituents, 2. Polymerization of 9‐allylanthracene and structures of the polymers
Authors: Dumitrescu Svetlana , Grigoraş Mircea , Simionescu Cristofor I.
Published: April 2003

Radical, cationic, and Ziegler‐Natta polymerizations of 9‐allylanthracene (1) were carried out. The radical polymerization was found to be an inefficient method leading to oligomers with complex structure. Reaction of initiator radicals and growing macroradicals with the anthryl group or with the allylic hydrogen leads to resonance stabilized radicals which stop the polymerization. The cationic and Ziegler‐Natta polymerizations gave a copolymer with 9‐anthrylmethylethylene units (8) (from normal 1,2 addition) and 9,10‐anthrylenepropylene units (11) (from the electrophilic attack of carbocations at the aromatic nucleus). Low polymerization temperatures lead to a preference for the alkylation reaction.
Estimation of the characteristic ratio of polyacrylamide in water and in a mixed theta‐solvent
Authors: Bohdanecký Miloslav , Petrus Vladimír , Sedláček Blahoslav
Published: April 2003

Solutions of nine polyacrylamide fractions (3300 g · mol−1 < molar mass < 800 000 g · mol−1) in water at 25°C and in a mixed theta‐solvent (Water‐methanol, 3:2 parts by volume) at 20°C were studied by light scattering, sedimentation and viscometry. From measurements in water the characteristic ratio was estimated to be C∞ = 8,5. A somewhat higher value was obtained in the mixed solvent. An explanation of the large span of the reported C∞ values is proposed.
Determination of the polarization direction of the UV bands of chromophore molecules by use of cyclodextrins
Authors: Kobayashi Nagao , Minato Shingo , Osa Tetsuo
Published: April 2003

Cyclodextrins (CDxs) were utilized to determine the polarization direction in the UV bands of aromatic compounds. By choosing CDxs of suitable size for an axial inclusion

Axial inclusion is the inclusion in which the long‐axis of arenes is parallel to the axis of the CDxs' cavity.

, the induced circular dichroism (ICD) bands of the included chromophore molecules are well resolved. Thus, except for the bands which consist of two or more perpendicularly polarized transitions with quite a different oscillator strength, the polarization direction is simply determined from the sign of ICD spectra: a plus sign is produced by transitions polarized parallel to the long‐axis while a negative sign by those polarized along the short‐axis. Besides being simple, this method is applicable to bands as short as 195 nm, since water is used as solvent. Thus, several UV bands of some compounds were recorded for the first time and even their polarization directions were determined. Merit and limitation of this method are discussed and compared with other methods.
Tight–loose coupling with customers: the enactment of customer orientation
Authors: Danneels Erwin
Published: April 2003

This article argues that tight linkages with customers present a paradox for the firm. The research question of this study is: What is the behavioral and cognitive process by which a firm establishes close links with its customers, and how can this process be both beneficial and detrimental? Existing theory and data from apparel retailers suggest that firms forge these tight links by enacting their customer environment. In the process of enactment, cognitions and actions reinforce each other and become increasingly focused. The tight coupling generated through enactment comes at the price of increased commitment and restricted vision. The author argues that firms should balance the natural process of tight coupling with a deliberate effort at loose coupling, and draws implications for further research on the organization‐environment interface. Copyright © 2003 John Wiley & Sons, Ltd.
Gastroschisis: can prenatal sonography predict neonatal outcome?
Authors: Japaraj R. P. , Hockey R. , Chan F. Y.
Published: April 2003

Objective

Gastroschisis is associated with significant neonatal morbidity, and occasionally mortality. Previous studies looking at ways to prognosticate this condition by antenatal ultrasound have shown conflicting results. The aim of this study was to evaluate the usefulness of prenatal sonographic parameters to predict neonatal outcome of gastroschisis.

Methods

The charts, photographs, and videotapes of all fetuses with gastroschisis who were assessed during pregnancy at the Mater Mothers' Hospital, Brisbane over an 8.5‐year period (Jan 1993—May 2001) were reviewed. Adverse neonatal outcome was defined as death, severe bowel complications (atresia, perforation, necrotic segments), need for multiple bowel operations, or a combination of these. Various sonographic parameters assessed included: gestation at first diagnosis, maximum bowel diameter, maximum bowel wall thickness, presence of other anomalies, evidence of growth restriction, and polyhydramnios.

Results

Forty‐five patients met the entry criteria during the study period. Six neonates died, 12 had severe bowel complications, and 15 had a combination of the adverse outcomes. Polyhydramnios was most significantly associated with severe bowel complications, with a likelihood ratio of 11.7 (P = 0.001). Other ultrasound parameters were not significantly correlated with neonatal outcome.

Conclusion

Most standard ultrasound parameters assessed antenatally in fetal gastroschisis were not significantly associated with adverse neonatal outcome, except for polyhydramnios, which was strongly predictive of severe bowel complications in the neonatal period. This information is important both for parents and for health professionals managing pregnancies with fetal gastroschisis. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Illness Behavior, Coping, and Health-Related Quality of Life
Authors: Rodríguez Antonio Galán , Picabia Alfonso Blanco , San Gregorio Angeles Pérez
Published: April 2003

The concepts of illness behavior (IB), coping (C), and health-related quality of life (HQL) are commonly used in the health field. Nevertheless, there are doubts about their ability to discriminate among groups of patients and to predict anxiety and depression levels in some medical settings. Three groups of patients (ambulatory chronic obstructive pulmonary disease ‘COPD’ patients, hospitalized COPD patients, and surgical lung cancer patients) were evaluated on the basis of these concepts using three standard questionnaires. Discriminant analysis was performed to study the discriminative properties of concepts; the eigenvalues were 3.470 (IB), 0.989 (C) and 5.591 (HQL). Stepwise multiple regression analyses were performed to identify the concepts and the scales that could best predict anxiety and depression. For anxiety, adjusted R2 were 0.408 (IB), 0.140 (C) and 0.633 (HQL); for depression, adjusted R2 were 0.264 (IB), 0.079 (C) and 0.635 (HQL). Coping had the greatest difficulty differentiating among persons suffering from different diseases; the efficiency to predict an affective state was poor in IB, C, and HQL. Some implications of the results are discussed.
Amyloid deposition in the hippocampus and entorhinal cortex: Quantitative analysis of a transgenic mouse model
Authors: Reilly John F. , Games Dora , Rydel Russell E. , Freedman Stephen , Schenk Dale , Young Warren G. , Morrison John H. , Bloom Floyd E.
Published: April 2003

Various transgenic mouse models of Alzheimer's disease (AD) have been developed that overexpress mutant forms of amyloid precursor protein in an effort to elucidate more fully the potential role of β-amyloid (Aβ) in the etiopathogenesis of the disease. The present study represents the first complete 3D reconstruction of Aβ in the hippocampus and entorhinal cortex of PDAPP transgenic mice. Aβ deposits were detected by immunostaining and thioflavin fluorescence, and quantified by using high-throughput digital image acquisition and analysis. Quantitative analysis of amyloid load in hippocampal subfields showed a dramatic increase between 12 and 15 months of age, with little or no earlier detectable deposition. Three-dimensional reconstruction in the oldest brains visualized previously unrecognized sheets of Aβ coursing through the hippocampus and cerebral cortex. In contrast with previous hypotheses, compact plaques form before significant deposition of diffuse Aβ, suggesting that different mechanisms are involved in the deposition of diffuse amyloid and the aggregation into plaques. The dentate gyrus was the hippocampal subfield with the greatest amyloid burden. Sublaminar distribution of Aβ in the dentate gyrus correlated most closely with the termination of afferent projections from the lateral entorhinal cortex, mirroring the selective vulnerability of this circuit in human AD. This detailed temporal and spatial analysis of Aβ and compact amyloid deposition suggests that specific corticocortical circuits express selective, but late, vulnerability to the pathognomonic markers of amyloid deposition, and can provide a basis for detecting prior vulnerability factors.
Restoration of blood flow by using continuous perimuscular infiltration of plasmid DNA encoding subterranean mole ratSpalax ehrenbergiVEGF
Authors: Roguin Ariel , Avivi Aaron , Nitecki Samy , Rubinstein Irit , Levy Nina S. , Abassi Zaid A. , Resnick Murray B. , Lache Orit , Melamed-Frank Meira , Joel Alma , Hoffman Aaron , Nevo Eviatar , Levy Andrew P.
Published: April 2003

The optimal vector, regulatory sequences, and method of delivery of angiogenic gene therapy are of considerable interest. TheSpalax ehrenbergisuperspecies live in subterranean burrows at low oxygen tensions and its tissues are highly vascularized. We tested whether continuous perimuscular administration ofSpalaxvascular endothelial growth factor (VEGF) DNA could increase tissue perfusion in a murine hindlimb ischemia model. Placebo or VEGF ± internal ribosome entry site (IRES) was continuously administrated perimuscularly in the ischemic zone by using an infusion pump. None of the mice in the VEGF-treated group (>50 μg) developed visible necrosis vs. 33% of the placebo group. Microscopic necrosis was observed only in the placebo group.SpalaxVEGF muscular infiltration resulted in a faster and more complete restoration of blood flow. The restoration of blood flow by VEGF was dose-dependent and more robust and rapid when using the VEGF–IRES elements. The flow restoration using continuous perimuscular infiltration was faster than single i.m. injections. Vessel density was higher in the VEGF and VEGF–IRES (−) groups compared with the placebo. Continuous perimuscular administration of angiogenic gene therapy offers a new approach to restore blood flow to an ischemic limb. Incorporation of an IRES element may assist in the expression of transgenes delivered to ischemic tissues. Further studies are needed to determine whether VEGF from the subterranean mole ratSpalaxVEGF is superior to VEGF from other species. If so, 40 million years ofSpalaxevolution underground, including adaptive hypoxia tolerance, may prove important to human angiogenic gene therapy.
Mammalian Erv46 localizes to the endoplasmic reticulum–Golgi intermediate compartment and to cis-Golgi cisternae
Authors: Orci Lelio , Ravazzola Mariella , Mack Gary J. , Barlowe Charles , Otte Stefan
Published: April 2003

Yeast endoplasmic reticulum (ER) vesicle protein Erv46p is a novel membrane protein involved in transport through the early secretory pathway. Investigation of mammalian Erv46 (mErv46) reveals that it is broadly expressed in tissues and protein-secreting cells. By immunofluorescence microscopy, mErv46 displays a crescent-shaped perinuclear staining pattern that is characteristic of the Golgi complex. Quantitative immunoelectron microscopy indicates that mErv46 is restricted to the cis face of the Golgi apparatus and to vesicular tubular structures between the transitional ER and cis-Golgi. Minor amounts of mErv46 reside in ER membranes and later Golgi cisternae. On Brefeldin A treatment, mErv46 redistributes to punctate structures that costain for ERGIC53. Depletion of mErv46 protein by RNA interference caused no apparent structural changes in the intermediate compartment or Golgi complex. These findings place mErv46 in a group of itinerant proteins that cycle between the ER and Golgi compartments such as ERGIC53 and the p24 proteins.
Identification of a small molecule inhibitor of the hedgehog signaling pathway: Effects on basal cell carcinoma-like lesions
Authors: Williams Juliet A. , Guicherit Oivin M. , Zaharian Beatrice I. , Xu Yin , Chai Ling , Wichterle Hynek , Kon Charlene , Gatchalian Christine , Porter Jeffery A. , Rubin Lee L. , Wang Frank Y.
Published: April 2003

The link between basal cell carcinoma (BCC) and aberrant activation of the Hedgehog (Hh) signaling pathway has been well established in humans and in mouse models. Here we report the development of assays, including two novel
in vitro
BCC models, which allowed us to screen for Hh inhibitors and test their validity as potential treatments for BCC. We identified a novel small molecule Hh inhibitor (CUR61414) that can block elevated Hh signaling activity resulting from oncogenic mutations in Patched-1. Moreover, CUR61414 can suppress proliferation and induce apoptosis of basaloid nests in the BCC model systems, whereas having no effect on normal skin cells. These findings directly demonstrate that the use of Hh inhibitors could be a valid therapeutic approach for treating BCC.
Localization of denaturation bubbles in random DNA sequences
Authors: Hwa Terence , Marinari Enzo , Sneppen Kim , Tang Lei-han
Published: April 2003

We study the thermodynamic and dynamic behaviors of twist-induced denaturation bubbles in a long, stretched random sequence of DNA. The small bubbles associated with weak twist are delocalized. Above a threshold torque, the bubbles of several tens of bases or larger become preferentially localized to AT-rich segments. In the localized regime, the bubbles exhibit “aging” and move around subdiffusively with continuously varying dynamic exponents. These properties are derived by using results of large-deviation theory together with scaling arguments and are verified by Monte Carlo simulations.
The endomembrane requirement for cell surface repair
Authors: McNeil Paul L. , Miyake Katsuya , Vogel Steven S.
Published: April 2003

The capacity to reseal a plasma membrane disruption rapidly is required for cell survival in many physiological environments. Intracellular membrane (endomembrane) is thought to play a central role in the rapid resealing response. We here directly compare the resealing response of a cell that lacks endomembrane, the red blood cell, with that of several nucleated cells possessing an abundant endomembrane compartment. RBC membrane disruptions inflicted by a mode-locked Ti:sapphire laser, even those initially smaller than hemoglobin, failed to reseal rapidly. By contrast, much larger laser-induced disruptions made in sea urchin eggs, fibroblasts, and neurons exhibited rapid, Ca2+-dependent resealing. We conclude that rapid resealing is not mediated by simple physiochemical mechanisms; endomembrane is required.
Circadian phase-specific degradation of the F-box protein ZTL is mediated by the proteasome
Authors: Kim Woe-Yeon , Geng Ruishuang , Somers David E.
Published: April 2003

Critical to the maintenance of circadian rhythmicity is the cyclic expression of at least some components of the central oscillator. High-amplitude cycling of mRNA and protein abundance, protein phosphorylation and nuclear/cytoplasmic shuttling have all been implicated in the maintenance of circadian period. Here we use a newly characterized
Arabidopsis
suspension cell culture to establish that the rhythmic changes in the levels of the clock-associated F-box protein, ZTL, are posttranscriptionally controlled through different circadian phase-specific degradation rates. This proteolysis is proteasome dependent, implicating ZTL itself as substrate for ubiquitination. This demonstration of circadian phase-regulated degradation of an F-box protein, which itself controls circadian period, suggests a novel regulatory feedback mechanism among known circadian systems.
Enhanced protein domain discovery by using language modeling techniques from speech recognition
Authors: Coin Lachlan , Bateman Alex , Durbin Richard
Published: April 2003

Most modern speech recognition uses probabilistic models to interpret a sequence of sounds. Hidden Markov models, in particular, are used to recognize words. The same techniques have been adapted to find domains in protein sequences of amino acids. To increase word accuracy in speech recognition, language models are used to capture the information that certain word combinations are more likely than others, thus improving detection based on context. However, to date, these context techniques have not been applied to protein domain discovery. Here we show that the application of statistical language modeling methods can significantly enhance domain recognition in protein sequences. As an example, we discover an unannotated Tf_Otx Pfam domain on the cone rod homeobox protein, which suggests a possible mechanism for how the V242M mutation on this protein causes cone-rod dystrophy.
Closing the loop: The PmrA/PmrB two-component system negatively controls expression of its posttranscriptional activator PmrD
Authors: Kato Akinori , Latifi Tammy , Groisman Eduardo A.
Published: April 2003

A fundamental question in biology is how an organism integrates multiple signals to mediate an appropriate cellular response. The PmrA/PmrB two-component system of
Salmonella enterica
can be activated independently by Fe
3+
, which is sensed by the PmrB protein, and in low Mg
2+
, which is sensed by the PhoQ protein. The low-Mg
2+
activation requires
pmrD
, a PhoP/PhoQ-activated gene that activates the response regulator PmrA at a posttranscriptional level. We now report that
pmrD
expression is negatively regulated by the PmrA/PmrB system. Conditions that activate the PmrA protein independently of
pmrD
, such as exposure to Fe
3+
, resulted in lower levels of
pmrD
transcription. The PmrA protein footprinted the
pmrD
promoter upstream of the PhoP-binding site but did not interfere with binding of the PhoP protein. Mutation of the PmrA-binding site in the
pmrD
promoter abolished PmrA-mediated repression. Negative regulation of the PhoP/PhoQ-activated
pmrD
gene by the PmrA/PmrB system closes a regulatory circuit designed to maintain proper cellular levels of activated PmrA protein and constitutes a singular example of a multicomponent feedback loop.
Advances in resistance welding for body‐in‐white
Authors: Rooks Brian
Published: April 2003

This paper describes the developments in the control of spot welding from Bosch Rexroth with particular reference to body‐in‐white applications. The Bosch Rexroth MF system uses 1 kHz rather than conventional 50 Hz in the control of spot welding and DC current rather than AC at the weld gun. The several benefits of this arrangement are discussed including lower power and energy losses, lighter cabling and a more compact weld transformer. Also described is a new ultrasonic adaptive control system developed by Bosch Rexroth which enables the growth of the weld nugget to be monitored and recorded for traceability.
IMTS leads with technological innovation
Authors: Bloss Dick
Published: April 2003

Innovation drives suppliers even as demand is soft. Modular assembly stations, compact part machining/turning systems, linear motor powered motion and smart end effectors lead the way as the industry drives ahead to provide added benefits to users and system integrators.
Optimum assembly design utilizing a behavioral modeling concept
Authors: Lin Y.J. , Farahati R.
Published: April 2003

This paper presents a versatile and economical knowledge‐based assembly design of blade and shell assemblies by employing behavioral modeling concepts. Behavioral modeling is a new generation CAD concept aimed at achieving ultimately optimum results with the efforts made in the early stage of the product development cycle. As a result, the assembly process of any odd‐configured parts such as torque converter blades, can be accurately planned, and made adaptable to all potential in‐process alterations due to either changes of components design or that of the assembly kinematics. Optimum assembly design is achieved when the volumetric interference meets a desired value based on an expert's determination. Experimental verification of the proposed optimum assembly design conducted in Luk, Inc. with two different blades' assemblies demonstrates satisfactory results.
Online reverse auction purchasing contracts
Authors: Emiliani M.L. , Stec D.J.
Published: April 2003

Discusses the types of terms and conditions that typically accompany purchasing contracts resulting from online reverse auctions for industrial components. Identifies the terms and conditions that perpetuate traditional batch‐and‐queue production practices. Concludes that buyers must construct terms and conditions that support the implementation of lean production by suppliers in order to achieve congruency with strategic business goals.
Endogenous Interleukin‐10 is Required for the Defervescence of Fever Evoked by Local Lipopolysaccharide‐Induced and Staphylococcus Aureus‐Induced Inflammation in Rats
Authors: Cartmell T. , Ball C. , Bristow A. F. , Mitchell D. , Poole S.
Published: April 2003

We tested the hypothesis that endogenous interleukin (IL)‐10 limits the fever induced by a Gram‐negative bacterial toxin (Escherichia coli lipopolysaccharide, LPS) and a Gram‐positive bacterial toxin (Staphylococcus aureus), when these toxins are injected into a subcutaneous air pouch (i.po.) in rats. Injection of LPS or S. aureus caused fevers that were reduced in amplitude and duration by simultaneous administration of rat recombinant IL‐10. The inhibition of fever by IL‐10 was accompanied by a significant reduction in the toxin‐evoked increases in concentrations of immunoreactive IL‐6 at the site of inflammation and of IL‐6 and IL‐1 receptor antagonist in the circulation. Conversely, neutralisation of endogenous IL‐10 in the pouch increased the amplitude and dramatically increased the duration of toxin‐evoked fever, and augmented toxin‐induced increases in pouch tumour necrosis factor‐α, IL‐1β, and especially IL‐6. Our data support a crucial regulatory role for endogenous IL‐10 in limiting the fever responses during both Gram‐negative and Gram‐positive infections.
Effect of Vitamin C Supplements on Antioxidant Defence and Stress Proteins in Human Lymphocytes and Skeletal Muscle
Authors: Khassaf M. , McArdle A. , Esanu C. , Vasilaki A. , McArdle F. , Griffiths R. D. , Brodie D. A. , Jackson M. J.
Published: April 2003

Oxidative stress induces adaptations in the expression of protective enzymes and heat shock proteins (HSPs) in a variety of tissues. We have examined the possibility that supplementation of subjects with the nutritional antioxidant, vitamin C, influences the ability of lymphocytes to express protective enzymes and HSPs following exposure to an exogenous oxidant and the response of skeletal muscle to the physiological oxidative stress that occurs during exercise in vivo. Our hypothesis was that an elevation of tissue vitamin C content would reduce oxidant‐induced expression of protective enzymes and HSP content. Lymphocytes from non‐supplemented subjects responded to hydrogen peroxide with increased activity of superoxide dismutase (SOD) and catalase, and HSP60 and HSP70 content over 48 h. Vitamin C supplementation at a dose of 500 mg day−1 for 8 weeks was found to increase the serum vitamin C concentration by ∼50 %. Lymphocytes from vitamin C‐supplemented subjects had increased baseline SOD and catalase activities and an elevated HSP60 content. The SOD and catalase activities and the HSP60 and HSP70 content of lymphocytes from supplemented subjects did not increase significantly in response to hydrogen peroxide. In non‐supplemented subjects, a single period of cycle ergometry was found to significantly increase the HSP70 content of the vastus lateralis. Following vitamin C supplementation, the HSP70 content of the muscle was increased at baseline with no further increase following exercise. We conclude that, in vitamin C‐supplemented subjects, adaptive responses to oxidants are attenuated, but that this may reflect an increased baseline expression of potential protective systems against oxidative stress (SOD, catalase and HSPs).
Paradoxical Ca2+ Rises induced by Low External Ca2+ in Rat Hippocampal Neurones
Authors: Burgo Andrea , Carmignoto Giorgio , Pizzo Paola , Pozzan Tullio , Fasolato Cristina
Published: April 2003

Confocal Ca2+ imaging of rat hippocampal slices shows a paradoxical effect of acute reductions of the [Ca2+]o. Upon slice perfusion with low‐Ca2+ media, a prompt intracellular Ca2+ rise selectively occurs in neurones. This response is observed only in slices challenged with agonists of group I metabotropic glutamate or M1 muscarinic receptors. In contrast, the intracellular Ca2+ level of non‐stimulated neurones is insensitive to reductions of [Ca2+]o. The phenomenon is observed in 20–25 % of cultured cortical neurones. Evidence is provided demonstrating that: (1) this paradoxical response is not due to a non‐specific decrease in divalent cation concentration but it is selectively activated by a reduction in [Ca2+]o, being maximal with [Ca2+]o between 0.25 and 0.5 mm; (2) upon maximal stimulation, 70–90 % of CA1‐CA3 pyramidal neurones sense a reduction in [Ca2+]o; a weaker response is observed in neurones from the neocortex, whereas neurones from the dentate gyrus and granule cells from the cerebellum fail to respond; (3) conditions that elicit paradoxical Ca2+ responses cause depolarisation and increase the firing rate of hippocampal neurones; (4) paradoxical Ca2+ rises depend, primarily, on Ca2+ influx through L‐type voltage‐operated Ca2+ channels and to a lesser extent on release from intracellular Ca2+ stores. Inhibition of phospholipase C or protein kinase C failed to suppress the neuronal response, whereas a selective inhibitor of the Src‐family of tyrosine kinases abolishes the paradoxical neuronal Ca2+ rise. A model is presented to explain how this response is elicited by contemporaneous reduction of the [Ca2+]o and metabotropic receptor stimulation; implications for the pathophysiology of the CNS are also discussed.
Prospective cohort study showing changes in the monthly incidence of Pneumocystis carinii pneumonia
Authors: Lubis N , Baylis D , Short A , Stebbing J , Teague A , Portsmouth S , Bower M , Nelson M , Gazzard B
Published: April 2003

Pneumocystis carinii pneumonia (PCP) remains a serious opportunistic infection in HIV infected individuals. Seasonal changes in climate are associated with changes within individual susceptibility to infection. The possibility of monthly variability in the incidence of PCP was therefore examined by means of a cohort study of a database of 8640 HIV infected individuals attending the Chelsea and Westminster Hospital. There were 792 cases of PCP diagnosed since 1985. A marked decline was observed in the incidence of PCP in mid-1992 coincident with the introduction of PCP prophylaxis. There was a further decline in 1996 after the introduction of highly active antiretroviral therapy. Despite no significant monthly variation in the mean attendance to clinic and CD4 count, both new and all cases of PCP were higher in January than in other months (15.9% and 14.5% of all cases, respectively). A correlation with low rainfall in January and new cases of PCP was observed. These data are consistent with an influence of climatic conditions on the presentation of PCP. The diagnosis of PCP is more common in winter months suggesting that this is a transmissible infection.
κ-DEFORMATIONS OF D = 3 CONFORMAL VERSUS DEFORMATIONS OF D = 4 AdS SYMMETRIES
Authors: LUKIERSKI J. , LYAKHOVSKY V. D. , MOZRZYMAS M.
Published: April 2003

We describe the classical o(3,2)r-matrices as generating the quantum deformations of either D = 3 conformal algebra with mass-like deformation parameters or D = 4 AdS algebra with dimensionless deformation parameters. We describe the quantization of classical o(3,2)r-matrices via Drinfeld twist method which locates the deformation in the coalgebra sector. Further we obtain the quantum o(3,2) algebra in a convenient Hopf algebra form by considering suitable deformation maps from classical to deformed o(3,2) algebra basis. It appears that if we pass from κ-deformed D = 3 conformal algebra basis, to the deformed D = 4 AdS generators basis, the role of dimensionful parameter is taken over by the AdS radius R. We also provide the bilinear o(3,2) Casimir which we express using the deformed D = 3 conformal basis.
Morphology of Pyramidal Neurones in Cytochrome Oxidase Modules of the S-I Bill Representation of the Platypus
Authors: Elston Guy N. , Manger Paul R. , Pettigrew John D.
Published: April 2003

The primary somatosensory cortex of the platypus (Ornithorhynchus anatinus) is characterized by a distinct array of functionally specific cytochrome oxidase (CO) modules, forming alternate CO-rich and CO-poor bands. In the current study, we undertook to establish whether the cellular morphology of layer V pyramidal neurones reflects this modular organization. To this end, we injected neurones with Lucifer Yellow in 250 μm thick, flat-mounted cortical slices and processed the tissue to reveal a light-stable reaction product. By aligning blood vessels in serial sections in which we injected individual neurones with sections processed for CO, we were able to establish the exact location of injected cells with respect to the pattern of CO bands. Pyramidal neurones in the CO-poor bands (which are responsive to both mechano- and electroreceptive stimuli) had basal dendritic fields that were larger than those in the CO-rich bands. The large basal dendritic fields of layer V pyramidal neurones in the CO-poor bands may allow for integration of a greater number of more diverse inputs, thus allowing for averaging of stimuli to improve the signal-to-noise ratio or enhance spatial discrimination of peripheral stimuli. In some instances, neurones located within approximately 100 μm of the boundaries of the CO bands had dendritic fields that appeared to conform to the CO bands, the dendrites preferentially arborizing within a single band and avoiding the neighbouring band. However, the bias was not absolute, as we observed many examples of cells with dendrites that crossed the boundary between bands. Furthermore, many cells had dendrites that showed distinct dendritic bias that bore no obvious relationship to the CO boundaries.
The Orthodox View of Brain Sexual Differentiation
Authors: Breedlove S. Marc , Cooke Bradley M. , Jordan Cynthia L.
Published: April 2003

The standard view of sexual differentiation of the brain, derived primarily from work with mammals, is that the same steroidal signal which permanently masculinizes the body early in life, androgen, also permanently masculinizes the nervous system. This oversimplified view overlooks the rich diversity of mechanisms produced by natural selection. We review the mechanisms underlying sexual differentiation of what may be the simplest mammalian model, the spinal nucleus of the bulbocavernosus (SNB), a system that is intimately associated with sexual differentiation of the periphery. Indeed, in many instances, early androgen can permanently masculinize the SNB system but, surprisingly, these early influences may depend to some extent on social mediating factors. Furthermore, in adulthood, androgen continues to affect the SNB system in diverse ways, acting on several different loci, indicating a life-long plasticity in even this simple system. Finally, there is evidence that adult androgens interact with social experience in order to affect the SNB system. Thus the SNB system displays a far richer array of interactions than the standard view of sexual differentiation would predict. Examination of other systems and other species, as depicted in the following reports, reveals a far more complicated, and far more interesting perspective on how the brains and behaviors of males and females diverge.
Development of NADPH-Diaphorase Activity in the Central Nervous System of the Cichlid Fish, Tilapia mariae
Authors: Villani Luigi
Published: April 2003

The distribution of nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity was studied in the cichlid fish Tilapia mariae during ontogenesis by the histochemical reaction of NADPH-diaphorase that indicates, in aldehyde-fixed tissue, the presence of nitric oxide synthase, which is the enzyme responsible for nitric oxide production. The first appearance of NADPH-diaphorase-positive neurons has a striking bilateral symmetry and occurs 20 h after fertilization (stage 8) in the olfactory placodes and in the neural tube where two clusters of positive neurons were seen in the diencephalon and in the rhombomere r4 of the hindbrain. Two days after fertilization (stage 10), the clusters of positive neurons showed labeled axons. The two longitudinal fiber bundles that arose from the diencephalic positive neurons ran caudally in the tract of the postoptic commissure. At stage 12 (3.5 days after fertilization), new populations of NADPH-diaphorase-positive neurons appeared in the telencephalon, in some diencephalic nuclei, and in the hypothalamus. Several trigeminal motor neurons showed strong NADPH-diaphorase activity, whereas the optic tectum and cerebellum were completely free of enzymatic activity. In the hindbrain, clusters of positive neurons were seen in the octavolateral region and in the region defined by the exit of the vagus nerve. In the cervical spinal cord, some ventral putative motor neurons were labeled. At stage 14 (5.5 days after fertilization), several periventricular neurons of the optic tectum and some neurons of the cerebellar lamina were labeled. Dorsal neurons, including a few large superficial neurons were also labeled in the cervical spinal cord. NADPH-diaphorase activity was seen in the neuropil area of the telencephalon, the target of olfactory inputs, and in the sensory dorso-lateral area of the spinal cord.
A Possible Pathway Connecting the Photosensitive Pineal Eye to the Swimming Central Pattern Generator in Young Xenopus laevis Tadpoles
Authors: Jamieson David , Roberts Alan
Published: April 2003

The pineal eye of young Xenopus laevis tadpoles mediates a swimming response to dimming. Our aim was to define pathways that allow pineal photoreceptors to influence the swimming central pattern generator (CPG) in the hindbrain and spinal cord. Retrograde filling with horseradish peroxidase (HRP) and carboxyfluorescein showed that: (1) pineal ganglion cells do not project to the hindbrain, and (2) diencephalic/mesencephalic descending (D/MD) neurons, which could be contacted by pineal ganglion cell axons, do project to the hindbrain. Lesion experiments demonstrated that ganglion cell axons form ipsilateral and contralateral connections, either of which is sufficient to mediate a swimming response. Latency measurements suggest that the contralateral pathway is stronger than the ipsilateral one. Multiple unit recordings from the midbrain in the region of the D/MD neurons showed short latency activity in response to dimming or a brief current pulse to pineal axons. This activity could last for many seconds after the stimulus. Pharmacological experiments showed that it depended on synaptic excitation and suggested that the ganglion cell transmitter is glutamate. If pineal ganglion cells excite midbrain D/MD neurons on both sides of the brain, the D/MD neuron projections to the hindbrain could excite the swimming CPG and initiate swimming.
The Ocular Morphology of the Southern Hemisphere Lamprey Mordacia mordax Richardson with Special Reference to a Single Class of Photoreceptor and a Retinal Tapetum
Authors: Collin Shaun P. , Pottert Ian C.
Published: April 2003

A description is given of the morphological and ultrastructural characteristics of the eye of Mordacia mordax, one of the two parasitic species of the southern hemisphere lamprey family Mordaciidae. The avascular retina is well-differentiated, containing two ganglion cell sublaminae, two layers of horizontal cells and a large population of displaced bipolar cells. Intermediate filaments, which stain positively for glial fibrillary acidic protein (GFAP), lie in perpendicularly-arranged bundles between the two layers of horizontal cells. M. mordax contains only a single type of rod-like photoreceptor, in contrast to representatives in the other two lamprey families Geotriidae and Petromyzontidae, which possess three (two cone-like and one rod-like) and two (one cone and one rod) types of photoreceptor, respectively. The large photoreceptors of M. mordax possess a large mitochondrial ellipsosome, a cylindrical outer segment with incisures, and a nucleus immediately abutting the outer limiting membrane. The photoreceptors are arranged in an hexagonal array with their outer segments surrounded by a retinal tapetum which elicits a yellow fundal eyeshine. The tapetum contains both diffuse (vitread spheroidal granules) and specular (sclerad needles) reflectors. The characteristics of the eye of M. mordax are related to the diurnal burrowing of this species during its upstream migration, a feature not found in the other two extant families of lampreys. The absence of cone-like photoreceptors and the presence of a tapetum suggest that although photopic vision is probably greatly diminished, characteristics have been evolved by the eye to maximize light capture and increase sensitivity in the low light intensities encountered during this species’ nocturnal migration.
Neurogenesis and the Evolution of Cortical Diversity: Mode, Tempo, and Partitioning during Development and Persistence in Adulthood
Authors: Kornack David R.
Published: April 2003

The mammalian cerebral cortex varies enormously in absolute and relative size across species. These size differences reflect phyletic differences in the number and organization of cortical neurons, which in turn imply evolutionary changes in the developmental program that generates these neurons. Whereas patterns of symmetric and asymmetric modes of progenitor cell division during cortical neurogenesis are widely conserved among species, other proliferation parameters, including the timing and number of cell divisions, vary considerably. This variation contributes to the development of cortical size differences in mammals in general, and the expansion of neocortex in anthropoid primates (monkeys, apes, and humans) in particular. The disproportionate enlargement of anthropoid neocortex might also arise from regional ‘border-shifting’ within the embryonic telencephalon, causing expansion of the neurogenic region allocated for producing neocortex and concomitant diminution of neighboring olfactory regions. Neurogenesis also shows substantial phyletic differences in adult hippocampus, an archicortical structure. Therefore, variation in neurogenesis across species is not only a feature of early development, but is also a trait of adult cortical diversity.