bluuebunny/crossref_metadata_2025 huggingface dataset:
A proposed strategy for seismic design of steel buildings
Authors: Kennedy DJL , Medhekar M S
Published: April 2011

The conceptual basis of the seismic design procedure in the National Building Code of Canada is reviewed. The design earthquake is specified only for the ultimate limit states at which the performance of both ordinary and important buildings is evaluated by an elastic static analysis in all zones. Criteria for checking the serviceability limit states, which apply to moderate earthquakes that may occur relatively frequently in the life of the building, are not specified explicitly. It is suggested that the current design approach could be improved by adopting a design strategy that addresses as well the serviceability limit states and associated evaluation criteria and gives methods for design and analysis as a function of the seismic zone and the importance of the structure. An earthquake with a return period of 1 in 50 years is proposed tentatively for the serviceability limit states with appropriate drift limits. The proposed serviceability limit states are shown to govern the design of buildings for values of the force modification factor greater, on average, than 3.Key words: analyses, earthquake, seismic design, serviceability limit state, steel, ultimate limit state.
Investigation of the behavior of circular concrete columns reinforced with carbon fiber reinforced polymer (CFRP) jackets
Authors: Purba Burt K , Mufti Aftab A
Published: April 2011

Recent advancements in the fields of fiber reinforced polymers (FRPs) have resulted in the development of new materials with great potential for applications in civil engineering structures, and due to extensive research over recent years, FRPs are now being considered for the design of new structures. This study describes how carbon fiber reinforced polymer jackets can be used to reinforce circular concrete columns. Fibers aligned in the circumferential direction provide axial and shear strength to the concrete, while fibers aligned in the longitudinal direction provide flexural reinforcement. Prefabricated FRP jackets or tubes would also provide the formwork for the columns, resulting in a decrease in labor and materials required for construction. Also, the enhanced behavior of FRP jacketed concrete columns could allow the use of smaller sections than would be required for conventionally reinforced concrete columns. Furthermore, FRP jacket reinforced concrete columns would be more durable than conventionally reinforced concrete columns and therefore would require less maintenance and have longer service life.Key words: bridge, carbon, column, concrete, confinement, fiber reinforced polymer, jacket, retrofitting, seismic, strengthening.
Seismic evaluation and retrofit with steel jackets of reinforced concrete bridge piers detailed with lap-splices
Authors: Daudey Xavier , Filiatrault André
Published: April 2011

Recent earthquakes around the world have confirmed the poor seismic behavior of reinforced concrete bridge piers incorporating typical pre-1971 reinforcement details. Since the 1971 San Fernando earthquake in California, procedures to evaluate accurately the flexural and shear behavior of reinforced concrete bridge piers, as well as retrofit techniques to address economically the most common deficiencies, have been elaborated. In eastern Canada, the majority of reinforced concrete bridge structures incorporate piers with similar reinforcement details as those that suffered severe damage, or collapse, during recent earthquakes in California and Japan. Very little research, however, has been conducted on the seismic behavior of these structures, which often exhibit complex cross-sectional geometries and lap-splices in the plastic hinge region. This paper presents a contribution towards a better understanding of the seismic behavior and retrofit of reinforced concrete bridge piers in eastern Canada through quasi-static tests performed on five 1/3.65-scale pier models of an existing bridge structure in the Montreal region. The first specimen was tested in its existing conditions, while the four others were retrofitted with steel jackets. The geometry of the jacket, the size of the gap at the base of the pier, and the properties of the fill material between the jacket and the original cross section were investigated in these last four tests. A numerical model, considering the bond-slip between the concrete and the longitudinal reinforcement, is proposed to simulate the experimental results. Key words: bond-slip, bridge piers, ductility, hysteresis loops, lap-splices, seismic retrofit, steel jackets.
Évolution du nombre de particules dans l'eau filtrée d'une filière de filtration directe utilisant le polychlorure d'aluminium
Authors: Ndiongue Souleymane , Desjardins Raymond , Prévost Michèle , Morissette Chantal
Published: April 2011

This text presents and discusses the performances of direct filtration evaluated by means of particle counts and turbidity of raw water in periods of low and high turbidity. It also deals with the relationships between the removals of particles measuring from 2 to 150 µm (total counts) and those of particles in the other size ranges, which vary from 2 to 5 and from 5 to 15 µm. The tests were carried out on a pilot plant (20 m3/h) that treats waters from the St. Lawrence River (Canada) using the polyaluminum chloride (PACl) coagulation method followed by rapid filtration at 10 m/h. The results show that when the turbidity of the raw water is low, it is not always possible to predict a filter breakthrough based on the turbidity of its effluent, whereas it is possible to do so by observing the evolution of the particle counts. There exist good correlations between the removals of the total particle counts (2-150 µm) and those of the counts of particles in the other size ranges (2-5 and 5-15 µm). Furthermore, the evolution of all these ranges of particle size reveals the same tendencies with respect to the quality of the filtered water.Key words: direct filtration, in-line filtration, filtration, particle counts, turbidity, polyaluminum chloride.
Estimation of discharge capacity in meandering compound channels using artificial neural networks
Authors: Liu Weiping , James C S
Published: April 2011

Flow in compound (or two-stage) channels is very complex and different energy loss mechanisms operate under different geometric and flow conditions. Neither theoretical analyses nor current empirical approaches are sufficiently developed for practical calculation of conveyance for all conditions experienced in practice. An alternative approach, using artificial neural network modelling, has been successfully applied to predict conveyance under a wide range of conditions. The model proposed uses a feed-forward system with one hidden layer and an error back-propagation learning procedure. It predicts a dimensionless discharge using input describing the main channel and floodplain flow depths, vegetation density over the cross section, channel sinuosity, transverse floodplain slope, and floodplain bend tightness. The discharge is dimensionalized by multiplication with the composite discharge calculated assuming frictional resistance only. The model was trained using 45 data sets representing a range of main channel and floodplain characteristics and tested using 15 additional data sets. The discharge prediction error for all the data used in development and testing the model was -0.19% on average and exceeded 15% for one condition only.Key words: compound channels, channel conveyance, flow resistance, neural networks.
Alkali-aggregate reactivity in Newfoundland, Canada
Authors: Bragg D
Published: April 2011

Alkali-aggregate reactivity is a chemical reaction that occurs in some concrete structures. This reaction causes expansion and cracking of concrete. It may not be the main cause of premature deterioration; however, it is often the catalyst for other forms of deterioration. Since 1989, field work and laboratory testing for alkali-reactivity has been undertaken on selected aggregate, rock, and concrete core samples throughout Newfoundland. The field work and laboratory tests consisted of an assessment of the bedrock and aggregate sites to determine their quality and quantity for use as construction material; an examination of existing concrete structures to assess their durability with regard to alkali-aggregate reactivity. The site investigation of the concrete structures consisted of noting their date of construction, the rock and aggregate types used, the types of cracking, and the degree and type of deterioration of each structure. Results from laboratory testing, petrographic examination, and visual observation show that certain sedimentary, igneous, and metamorphic rock types may be potentially alkali-reactive, but the reaction may not always be deleterious to the concrete structure.Key words: alkali-aggregate reaction, concrete structures, laboratory tests, petrographic examination, rock types.
Experience with alkali-aggregate reaction in the Canadian prairie region
Authors: Roy STR , Morrison J A
Published: April 2011

This paper summarizes alkali-aggregate reaction (AAR) experience in the prairie region to date. Information is presented on reactive rock types and their geological significance, laboratory test data, field evidence of affected structures, and industry practices for preventive measures and management of affected structures. The frequency and severity of documented AAR-affected structures in Manitoba, Saskatchewan, and Alberta is low, Alberta having the highest incidence. A significant number of aggregate sources in the region show potential for excessive expansion when subjected to laboratory testing. The lack of field evidence is generally attributed to the lower alkali contents of cements that have historically been produced and used in the region. Limited number and extent of searches for affected structures, inadequate diagnosis of the phenomenon, and client confidentiality are also factors. It is imperative that specifiers, owners, researchers, suppliers, and producers be aware of the potential reactivity of local aggregates. The occurrences of AAR-related deterioration in the field demonstrates that the phenomenon is not limited to the laboratory. The effectiveness of low to moderate alkali contents of concrete mixtures in controlling the AAR phenomenon demonstrates the need to specify low-alkali cement and the importance of measuring the effectiveness of supplementary cementing materials in preventing AAR. There is a need to conduct extensive field searches for affected structures and it is important that suspected cases of AAR be properly diagnosed.Key words: alkali-aggregate reaction, concrete, Manitoba, Saskatchewan, Alberta, laboratory testing, field evidence, pattern cracking, prisms, mortar bars, prevention, management.
SimCon: the development and implementation of a simulation-based project control methodology
Authors: Chehayeb Nader N , Abou Rizk Simaan M , Brown Susan S
Published: April 2011

A project control methodology that employs computer simulation is presented. Strategies presented and discussed include creating a production-based hierarchical project breakdown structure, reporting by exception, and additions to CYCLONE that make it possible to track and compare budgeted production against actual production for multiple processes and continually link repetitive processes. The prototype is illustrated through a case study building project.Key words: simulation, control, planning, estimating, production reports, hierarchical project breakdown.
Alkali-aggregate reactivity in Québec (Canada)
Authors: Bérubé Marc-André , Durand Benoit , Vézina Daniel , Fournier Benoit
Published: April 2011

In the province of Québec, due to the particular geology and the historic use of high-alkali cements, a large number of concrete structures are affected by alkali-silica reactivity (ASR). Consequently, tremendous effort was made in this province during the last 20 years on (1) the determination in the laboratory (testing methods) as well as in the field (inspection of structures) of the potential alkali-aggregate reactivity (AAR) of concrete aggregates, (2) the prevention of AAR in new structures, and (3) the management of existing structures affected by this problem. For new structures, the most popular measure used in Québec in the presence of potentially reactive aggregates consists of limiting the alkali contribution by the cement to 3 kg/m3 of concrete (Na2Oeq). Also, blended silica fume cements were used on many occasions against ASR; ternary cements containing fly ash and silica fume, which proved in the laboratory to be effective against ASR, are presently available. As concerns the existing structures affected by ASR, many of them were repaired using various techniques ranging from the simple application of a penetrating sealer to the application of post-constraints or slot cutting.Key words: aggregate, alkali-aggregate reaction, cement, concrete, diagnosis, management, preventive measures, prognosis, Québec, testing.
Le béton projeté : nouveaux développements et applications
Authors: Jolin Marc , Lacombe Pierre
Published: April 2011

This paper presents the most recent developments in shotcrete technology obtained in the last 5 years through the "Industrial Chair on Shotcrete and Concrete Repair" hosted at Laval University. The main goal of this paper is to inform those involved in the construction and repair of civil engineering concrete structures of the various possibilities of "shotcrete." The two first sections present the basic principles in pneumatic application of concrete along with the two processes in shotcrete technology, the dry-mix and wet-mix. The advantages of both processes as well as the general rules to follow in a shotcrete application are also presented and explained. The third and last section, the most important, highlights the latest developments in shotcrete technology. These developments concern the use of set accelerating admixtures in dry process shotcrete and their effects on the durability of materials, the use of liquid and powdered air-entraining admixtures in dry-mix shotcrete as well as the concept of "high initial air content" in wet mix shotcrete.Key words: shotcrete, set accelerator, air-entraining admixture, durability, setting time.
A simplified method for seismic analysis of lattice telecommunication towers
Authors: Khedr Mohamed A , McClure Ghyslaine
Published: April 2011

A simplified static method for estimating the member forces in self-supporting lattice telecommunication towers due to both horizontal and vertical earthquake excitations is presented in this paper. The method is based on the modal superposition technique and the response spectrum approach, which are widely used for seismic analysis of linear structures. It is assumed that the lowest three flexural modes of vibration are sufficient to correctly estimate the tower's response to horizontal excitation, while only the lowest axial mode is sufficient to capture the response to vertical excitation. An acceleration profile along the height of the tower is defined using estimates of the lowest three flexural modes or the lowest axial mode, as appropriate, together with the spectral acceleration values corresponding to the associated natural periods. After the mass of the tower is calculated and lumped at the leg joints, a set of equivalent static lateral or vertical loads can be determined by simply multiplying the mass profile by the acceleration profile. The tower is then analyzed statically under the effect of these loads to evaluate the member forces. This procedure was developed on the basis of detailed dynamic analysis of ten existing three-legged self-supporting telecommunication towers with height range of 30-120 m. The maximum differences in member forces obtained with the proposed method and the detailed seismic analysis are of the order of ±25% in the extreme cases, with an average difference of ±7%. The results obtained for two towers with heights of 66 and 83 m are presented in this paper to demonstrate the accuracy and practicality of the proposed method.Key words: self-supporting tower, earthquake, vertical excitation, dynamic analysis.
The interaction of complement components with Aeromonas species
Authors: Brenden R. A. , Janda J. M.
Published: April 2011

The interaction of seven serum-sensitive Aeromonas strains with the complement system was investigated using a 2-h quantitative assay. Of the strains tested, four isolates activated both the alternative and classical pathways, two activated only the alternative pathway, and one strain was sensitive to the bactericidal action of complement through the classical pathway only. Two of the four Aeromonas caviae strains were such efficient activators of the complement system that when challenged with human sera deficient in normal concentrations of C3 and C4, they were still subject to complement-mediated bacterial lysis. This phenomenon, in conjunction with previous studies on complement activation by Aeromonas spp., may help account for the decreased incidence observed of systemic disease caused by Aeromonas caviae.
Intracellular salt concentrations of the anaerobic halophilic eubacteria Haloanaerobium praevalens and Halobacteroides halobius
Authors: Oren Aharon
Published: April 2011

The obligately anaerobic, moderately halophilic eubacteria Haloanaerobium praevalens (isolated from Great Salt Lake, Utah) and Halobacteroides halobius (isolated from the Dead Sea) were found to contain high intracellular potassium concentrations (0.76–2.05 M, not well correlated with the external NaCl concentration), and high intracellular sodium concentrations (0.28–2.6 M, increasing with increasing extracellular NaCl concentration). The sum of intracellular potassium and sodium concentrations approximated the total cation concentration of the medium. Internal chloride concentrations in Haloanaerobium praevalens equalled the external chloride concentration. Organic solutes, such as betaine, glycerol, and different amino acids that have been shown to serve as compatible solutes in other halophilic eubacteria and eukaryotic organisms, were not found in significant concentrations. Analysis of the amino acids in the proteins of the anaerobic halophilic eubacteria showed an excess of acidic amino acids, similar to that reported in halophilic archaebacteria of the genus Halobacterium.
Neuropeptide Y family of peptides: Structure, anatomical expression, function, and molecular evolution
Authors: Cerdá-Reverter José Miguel , Larhammar Dan
Published: April 2011

Evolutionary relationships between neuroendocrine peptides are often difficult to resolve across divergent phyla due to independent duplication events in different lineages. Thanks to peptide purification and molecular cloning in many different species, the situation is beginning to clear for the neuropeptide Y (NPY) family, which also includes peptide YY (PYY), the tetrapod pancreatic polypeptide (PP) and the fish pancreatic peptide Y (PY). It has long been assumed that the first duplication to occur in vertebrate evolution generated NPY and PYY, as both of these are found in all gnathostomes as well as lamprey. Evidence from other gene families show that this duplication was probably a chromosome duplication event. The origin of a second PYY peptide found in lamprey remains to be explained. Our recent cloning of NPY, PYY and PY in the sea bass proves that fish PY is a separate gene product. We favour the hypothesis that PY is a duplicate of the PYY gene and that it may have occurred late in fish evolution, as PY has so far only been found in acanthomorph fishes. Thus, this duplication seems to be independent of the one that generate PP from PYY in tetrapods, although both tetrapod PP and fish PY are expressed in the pancreas. Studies in the sea bass and other fish show that PY, in contrast to PP, is expressed in the nervous system. We review the literature on the distribution and functional aspects of the various NPY-family peptides in vertebrates.

Key words: neuropeptide Y, pancreatic polypeptide, fish pancreatic peptide, gene duplication.
Transcriptional repression of TRH promoter function by T3: analysis by in vivo gene transfer
Authors: Guissouma Hajer , Becker Nathalie , Seugnet Isabelle , Demeneix Barbara A
Published: April 2011

We consider how an integrated in vivo model can be used to study the specific transcriptional effects of specific receptors in neuroendocrine systems. Our example is the role of thyroid receptor (TR) isoforms in mediating negative feedback effects of T3on TRH (thyrotropin releasing hormone) expression. The in vivo transfection method employed polyethylenimine (PEI) to introduce genes directly into specifc regions of the brains of mice, rats, and Xenopus tadpoles. In the mouse model, the technique has served to examine TR effects on TRH transcription and on the pituitary-thyroid axis end point: thyroid hormone secretion. When a TRH-luciferase construct is introduced into the hypothalami of newborn mice TRH-luciferase transcription is regulated physiologically, being significantly increased in hypothyroidism and decreased in T3-treated animals. When various T3-binding forms of TRβ or TRα are expressed in the hypothalamus, all TRβ isoforms give T3-dependent regulation of TRH transcription, whereas TRα isoforms block T3-dependent transcription. Moreover, TR transcriptional effects are correlated with physiological consequences on circulating T4. Thus, somatic gene transfer shows TR subtypes to have distinct, physiologically relevant effects on TRH transcription. The approach is an appealing alternative to germinal transgenesis for studying specific neuroendocrine regulations at defined developmental stages in different species.Key words: thyroid hormone, TRH, mouse central nervous system, non viral gene transfer, polyethylenimine.
Basic mechanisms of secretion: sorting into the regulated secretory pathway
Authors: Blázquez Mercedes , Shennan Kathleen I
Published: April 2011

Targeting proteins to their correct cellular location is crucial for their biological function. In neuroendocrine cells, proteins can be secreted by either the constitutive or the regulated secretory pathways but the mechanism(s) whereby proteins are sorted into either pathway is unclear. In this review we discuss the possibility that sorting is either an active process occurring at the level of the trans-Golgi network, or that sorting occurs passively in the immature granules. The possible involvement of protein-lipid interactions in the sorting process is also raised.

Key words: lipid rafts, regulated secretory pathway, secretion, sorting receptors, sorting signals, trans-Golgi network.
Corticosteroid actions from neuronal membrane to behavior: Neurophysiological mechanisms underlying rapid behavioral effects of corticosterone
Authors: Rose James D
Published: April 2011

Investigation of the rapid suppression of male courtship clasping behavior by corticosterone in roughskin newts (Taricha granulosa) has led to the identification of a specific neuronal membrane receptor for this stress steroid. This paper describes studies of the neurophysiological effects of the rapid, membrane receptor mediated action of corticosterone on neurons that are involved in the control of clasping. In freely behaving newts, medullary neurons, including reticulospinal neurons, process clasp-triggering sensory signals and participate in control of clasping movements. Corticosterone injection causes these brainstem neurons to show selective depression of clasping-related sensorimotor function. These corticosterone effects appear in 3-10 min and are closely associated with the simultaneous depression of clasping. In addition to these functionally specific effects, corticosterone simultaneously causes widespread, primarily depressive effects on neuronal activity and excitability in the medulla and elsewhere in the brain. Thus, the membrane actions of corticosterone lead to diverse neural effects, including changes in membrane excitability as well as specific, network-level actions that are apparent only during behavior. These rapid corticosterone effects strongly interact with actions of the neuropeptides vasotocin and corticotropin-releasing factor, such that the form and magnitude of the steroid's effects depend on the prevailing neuroendocrine state of the brain.Key words: glucocorticoid, membrane receptor, non-genomic, amphibian, reproduction.
DNases and apoptosis
Authors: Counis M F , Torriglia A
Published: April 2011

Here we review the different apoptotic DNases. From a functional point of view, DNases implicated in apoptosis may be classified into three groups: the Ca2+/Mg2+endonucleases, the Mg2+-endonucleases, and the cation-independent endonucleases. The first group includes DNase I which has no specificity for the linker region, DNase gamma which has some homology with DNase I, and other DNases which cleave DNA in the linker region. Both DNase I and DNase gamma have been cloned. The other nucleases of this category have dispersed molecular weights. Their sequences are unknown and it is difficult to determine their role(s) in apoptosis. It seems that different pathways are present and that these nucleases may be activated either by caspases or serine proteases. The caspase 3 activated DNase (CAD, CPAN, or DFF40) belongs to the Mg2+-dependent endonucleases. DNase II belongs to the third group of acid endonucleases or cation-independent DNases. We have shown the involvement of DNase II in lens cell differentiation. Recently, the molecular structure of two different enzymes has been elucidated, one of which has a signal peptide and appears to be secreted. The other, called L-DNase II, is an intracellular protein having two enzymatic activities; in its native form, it is an anti-protease, and after posttranslational modification, it becomes a nuclease.Key words: endonucleases, apoptosis, caspases, serine proteases.
Pattern formation in the cerebellar cortex
Authors: Armstrong Carol L , Hawkes Richard
Published: April 2011

The cerebellar cortex is subdivided rostrocaudally and mediolaterally into a reproducible array of zones and stripes. This makes the cerebellum a valuable model for studying pattern formation in the vertebrate central nervous system. The structure of the adult mouse cerebellar cortex and the series of embryological events that generate the topography are reviewed.Key words: zebrin, Hsp25, Purkinje cells.
Hedgehog signaling and the axial patterning ofDrosophilawings
Authors: Brook William J
Published: April 2011

Growth and cell fate in the anterior-posterior (A/P) axis of the developing wing of Drosophila melanogaster are controlled by a stripe of cells bisecting the axis called the A/P organizer. Hedgehog (Hh) signaling from posterior to anterior cells induces the organizer. Several Hh-responsive genes expressed by cells of the organizer mediate its patterning activity. The Hh-signaling pathway controls the post-translational modification of the transcription factor Cubitus-interruptus (Ci) and the resulting local activation of Ci is required for the correct location of the A/P organizer.Key words: Hedgehog, morphogen, Drosophila, limb development, signal transduction.
The interaction of ferrocytochromecwith long-chain fatty acids and their CoA and carnitine esters
Authors: Stewart J M , Blakely J A , Johnson M D
Published: April 2011

Non-covalent modification of cytochrome c may have implications for electron transport and energy metabolism. We examined the interaction of various fatty acids (FAs), their coenzyme A and carnitine esters, and fatty alcohols with horse heart ferrocytochrome c. A comparison of FAs indicated a minimum chain length of 14 carbons was required for significant effect on the ferroheme chromophore and major changes in electronic spectra. Coenzyme A and carnitine esters interacted less strongly than FAs whereas long-chain alcohols did not interact with the protein. We found a single, saturable FA binding site with Kd(oleate) of 23.1 µM (by stopped-flow kinetics), 30 µM (by radiochemical binding assay), and 29 µM (by spectrophotometric assay). The binding stoichiometry was 1:1. We present evidence from electronic spectra, and proton NMR (nuclear magnetic resonance) that the SFe coordination (methionine 80) was disrupted by ligand binding. From molecular modeling we identify a putative binding channel flanked by lysines 72 and 73.Key words: cytochrome c, fatty acids, acyl-CoA, acyl-carnitine.
Localization of myosin Va is dependent on the cytoskeletal organization in the cell
Authors: Lionne Corinne , Buss Folma , Hodge Tony , Ihrke Gudrun , Kendrick-Jones John
Published: April 2011

Myosin V plays an important role in membrane trafficking events. Its implication in the transport of pigment granules in melanocytes and synaptic vesicles in neurons is now well established. However, less is known about its function(s) in other cell types. Finding a common function is complicated by the diversity of myosin V expression in different tissues and organisms and by its association with different subcellular compartments. Here we show that myosin V is present in a variety of cells. Within the same cell type under different physiological conditions, we observed two main cellular locations for myosin V that were dependent on the dynamics of the plasma membrane: in cells with highly dynamic membranes, myosin V was specifically concentrated at the leading edge in membrane ruffles, whereas in cells with less dynamic membranes, myosin V was enriched around the microtubule-organizing center. The presence of myosin V in the leading ruffling edge of the cell was induced by growth factor stimulation and was dependent on the presence of a functional motor domain. Moreover, myosin V localization at the microtubule-organizing center was dependent on the integrity of the microtubules. In polarized epithelial cells (WIF-B), where the microtubule-organizing region is close to the actin-rich apical surface, one single pool of myosin V, sensitive to the integrity of both microtubules and actin filaments, was observed.Key words: cell motility, cytoskeleton dynamics, molecular motors, mouse brain unconventional myosin Va, ruffles.
Effect of prevention and potentiation of diisopropyl phosphorofluoridate (DFP)-induced delayed neurotoxicity on the mRNA expression of neurofilament subunits in hen central nervous system
Authors: Xie Keqin , Gupta Ram P , Abou-Donia Mohamed B
Published: April 2011

Diisopropyl phosphorofluoridate (DFP) is an organophosphorus ester, which produces mild ataxia in 714 days and severe ataxia or paralysis in about 20 days (OPIDN) in hens. Previous studies in this laboratory have shown enhanced temporal expression of neurofilament (NF) subunit mRNAs in the spinal cord (SC) of DFP-treated hens. The main objective of this investigation was to study the effect of DFP administration on NF subunit mRNAs expression, when OPIDN is protected or potentiated by pre-treatment or post-treatment, respectively, with phenylmethylsulfonyl fluoride (PMSF). The hens were sacrificed 1, 5, 10, and 20 days after the last treatment. In contrast with enhanced mRNA expression of NF subunits reported in OPIDN, there was no alteration in the expression of NF subunits in the SC of PMSF-protected hens that did not develop OPIDN. PMSF post-treatment of DFP-treated hens, which enhanced delayed neurotoxicity produced by a low dose of DFP, exhibited decrease in the mRNA expression of NF subunits in SC at all time periods (120 days) of observation. The expression of NF subunits was also studied in the degeneration-resistant tissue cerebrum of treated hens. The results from protected hens suggested that temporal enhanced expression of NF subunit mRNAs in DFP-treated hens might be contributing to the development of OPIDN in hens. By contrast, PMSF post-treatment seemed to potentiate OPIDN by a mechanism different from that followed by DFP alone to produce OPIDN.Key words: diisopropyl phosphorofluoridate, phenylmethylsulfonyl fluoride, hen, spinal cord, neurofilament mRNAs.
Class II histone deacetylases: Structure, function, and regulation
Authors: Bertos Nicholas R , Wang Audrey H , Yang Xiang-Jiao
Published: April 2011

Acetylation of histones, as well as non-histone proteins, plays important roles in regulating various cellular processes. Dynamic control of protein acetylation levels in vivo occurs through the opposing actions of histone acetyltransferases and histone deacetylases (HDACs). In the past few years, distinct classes of HDACs have been identified in mammalian cells. Class I members, such as HDAC1, HDAC2, HDAC3, and HDAC8, are well-known enzymatic transcriptional corepressors homologous to yeast Rpd3. Class II members, including HDAC4, HDAC5, HDAC6, HDAC7, and HDAC9, possess domains similar to the deacetylase domain of yeast Hda1. HDAC4, HDAC5, and HDAC7 function as transcriptional corepressors that interact with the MEF2 transcription factors and the N-CoR, BCoR, and CtBP corepressors. Intriguingly, HDAC4, HDAC5, and probably HDAC7 are regulated through subcellular compartmentalization controlled by site-specific phosphorylation and binding of 14-3-3 proteins; the regulation of these HDACs is thus directly linked to cellular signaling networks. Both HDAC6 and HDAC9 possess unique structural modules, so they may have special biological functions. Comprehension of the structure, function, and regulation of class II deacetylases is important for elucidating how acetylation regulates functions of histones and other proteins in vivo.Key words: histone acetylation, protein acetylation, histone deacetylase, 14-3-3 proteins.
Contribution of leucine 85 to the structure and function ofSaccharomyces cerevisiaeiso-1 cytochromec
Authors: Parrish Jonathan C , Guillemette J Guy , Wallace Carmichael JA
Published: April 2011

Cytochrome c is a small electron-transport protein whose major role is to transfer electrons between complex III (cytochrome reductase) and complex IV (cytochrome c oxidase) in the inner mitochondrial membrane of eukaryotes. Cytochrome c is used as a model for the examination of protein folding and structure and for the study of biological electron-transport processes. Amongst 96 cytochrome c sequences, residue 85 is generally conserved as either isoleucine or leucine. Spatially, the side chain is associated closely with that of the invariant residue Phe82, and this interaction may be important for optimal cytochrome c activity. The functional role of residue 85 has been examined using six site-directed mutants of Saccharomyces cerevisiae iso-1 cytochrome c, including, for the first time, kinetic data for electron transfer with the principle physiological partners. Results indicate two likely roles for the residue: first, heme crevice resistance to ligand exchange, sensitive to both the hydrophobicity and volume of the side chain; second, modulation of electron-transport activity through maintenance of the hydrophobic character of the protein in the vicinity of Phe82 and the exposed heme edge, and possibly of the ability of this region to facilitate redox-linked conformational change.Key words: protein engineering, cytochrome c, structure-function relations, electron transfer, hydrophobic packing.
The integration of tissue structure and nuclear function
Authors: Maxwell Christopher A , Hendzel Michael J
Published: April 2011

Living cells can filter the same set of biochemical signals to produce different functional outcomes depending on the deformation of the cell. It has been suggested that the cell may be "hard-wired" such that external forces can mediate internal nuclear changes through the modification of established, balanced, internal cytoskeletal tensions. This review will discuss the potential of subnuclear structures and nuclear chromatin to participate in or respond to transduction of mechanical signals originating outside the nucleus. The mechanical interactions of intranuclear structure with the nuclear lamina will be examined. The nuclear lamina, in turn, provides a structural link between the nucleus and the cytoplasmic and cortical cytoskeleton. These mechanical couplings may provide a basis for regulating gene expression through changes in cell shape.Key words: gene expression, cell structure, nuclear structure, mechanotransduction, chromatin.
The emerging role of class II histone deacetylases
Authors: Fischle Wolfgang , Kiermer Veronique , Dequiedt Franck , Verdin Eric
Published: April 2011

Histone acetylation and deacetylation play essential roles in modifying chromatin structure and regulating gene expression in all eukaryotes. Several histone acetyltransferases have been identified that act as transcriptional coactivators. In contrast, histone deacetylases (HDACs) are part of transcriptional corepressor complexes. Based on their similarity to known yeast factors, the human HDACs are grouped into three classes. Class I HDACs are similar to the yeast transcriptional repressor yRPD3, while class II HDACs are related to yHDA1 and class III HDACs to ySIR2. In this review, we focus on the biology of class II HDACs. These newly discovered enzymes have been implicated in cell differentiation and development, and many molecular details are emerging that shed light on class II HDAC function and regulation. We discuss the biological role of these factors in the context of physiological processes.Key words: transcriptional regulation, histone deacetylases, class II HDACs, nucleocytoplasmic shuttling, MEF2.
Galectin-3-mediated adherence ofProteus mirabilisto Madin-Darby canine kidney cells
Authors: Altman Eleonora , Harrison Blair A , Latta Roger K , Lee Kok K , Kelly John F , Thibault Pierre
Published: April 2011

Proteus mirabilis is an important cause of urinary tract infections (UTIs) and can result in acute pyelonephritis. Proteus mirabilis expresses several, morphologically distinct, fimbrial species, and previous studies have shown that the nonagglutinating fimbriae (NAF) mediate bacterial adherence to a number of cell lines, including Madin-Darby canine kidney (MDCK) cells. Immunoblot overlay analysis of the plasma membrane fraction from MDCK cells with purified NAF revealed a 34-kDa band, which has been analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Database search identified galectin-3 as a potential protein candidate. Immunocytochemical assay of MDCK cells with a galectin-3-specific monoclonal antibody, anti-Mac-2, confirmed its presence on the plasma membrane extracellular surface. Preincubation of P. mirabilis with anti-Mac-2 monoclonal antibodies, specific for galectin-3, resulted in the inhibition of bacterial binding to MDCK cells. These data suggest a role for galectin-3, interacting with appropriately glycosylated surface receptors and P. mirabilis fimbriae, as a mediator of bacterial adherence in vitro.Key words: bacterial adherence, fimbriae, galectin-3, mass spectrometry.
Lipid metabolism and vesicle trafficking: More than just greasing the transport machinery
Authors: McMaster Christopher R
Published: April 2011

The movement of lipids from their sites of synthesis to ultimate intracellular destinations must be coordinated with lipid metabolic pathways to ensure overall lipid homeostasis is maintained. Thus, lipids would be predicted to play regulatory roles in the movement of vesicles within cells. Recent work has highlighted how specific lipid metabolic events can affect distinct vesicle trafficking steps and has resulted in our first glimpses of how alterations in lipid metabolism participate in the regulation of intracellular vesicles. Specifically, (i) alterations in sphingolipid metabolism affect the ability of SNAREs to fuse membranes, (ii) sterols are required for efficient endocytosis, (iii) glycerophospholipids and phosphorylated phosphatidylinositols regulate Golgi-mediated vesicle transport, (iv) lipid acylation is required for efficient vesicle transport mediated membrane fission, and (v) the addition of glycosylphosphatidylinositol lipid anchors to proteins orders them into distinct domains that result in their preferential sorting from other vesicle destined protein components in the endoplasmic reticulum. This review describes the experimental evidence that demonstrates a role for lipid metabolism in the regulation of specific vesicle transport events.Key words: vesicle transport, trafficking, lipid, sterol, metabolism.
Swelling of mitochondria induced by juvenile hormone in larval salivary glands ofDrosophila melanogaster
Authors: Farka Robert , ut'áková Gabriela
Published: April 2011

Treatment of Drosophila larval salivary glands with juvenile hormone or its analogues leads to ultrastructural changes of mitochondria that mimic those seen after application of uncouplers of oxidative phosphorylation. This alteration of mitochondria, also known as swelling, is manifested in strong dilatation of their intercristae space. The mitochondrial response of salivary glands to juvenile hormone is restricted to collum cells that are known to be ultrastructurally and functionally different from transitional and corpus cells and may reflect their specialization in energy metabolism and water/ion balance. Morphological change of mitochondria and about a fivefold increase in cytochrome c oxidase activity in response to juvenile hormone appear to be a consequence of uncoupling of oxidative phosphorylation. We have noticed no significant difference of the responses in Methoprene, the juvenile hormone resistant mutant, suggesting that this action of juvenile hormone may be mediated via a mechanism different from that using nuclear transcription factors. The "uncoupling" effect is caused also by juvenile hormone analogues which are considered inactive in producing morphogenetic effects in Drosophila. Mitochondrial response is independent of transcription and translation, as revealed by the use of RNA and protein synthesis inhibitors. Given these data together, we reasoned that the protonophoric/uncoupling effect of juvenile hormone is a cell type specific nongenomic response to this lipophilic ligand and contrasts with widely accepted notions about nuclear action of juvenile hormone.Key words: Drosophila, salivary glands, juvenile hormone, uncoupling, mitochondria, oxidative phosphorylation.
Comparative protection against oxyradicals by three flavonoids on cultured endothelial cells
Authors: Zeng Ling-Hua , Wu Jun , Fung Beverly , Tong Jeffrey H , Mickle Donald , Wu Tai-Wing
Published: April 2011

Oxygen-derived free radicals are known to injure the endothelium of aorta in diverse disorders. In this study we compared the cytoprotective effects of three flavonoids against oxyradical damage to porcine aortic endothelial cells in vitro. Cultured porcine aortic endothelial cells were exposed to oxyradicals generated by xanthine oxidase - hypoxanthine (XO-HP). The cytoprotective activities of morin, quercetin, and catechin on these systems were compared using established morphologic criteria. The results in the XO-HP system showed that morin at 0.125, 0.25, and 0.5 mM delayed cell necrosis to 27.4 ± 1.3, 46.8 ± 1.8, and longer than 70 min, respectively, compared with 12.0 ± 1.3 min in the control group. These degrees of protection were significantly stronger than those provided by quercetin and catechin at corresponding concentrations (p < 0.01). Morin and quercetin were moderate inhibitors of xanthine oxidase on the basis of the oxygen consumption rate, whereas catechin at the same concentrations had little inhibitory effect. The data from uric acid formation and cytochrome c reduction were consistent with the oxygen consumption measurement for the three flavonoids.

Key words: flavonoids, oxyradicals, aortic endothelial cells.
Spatially distinct domains of cell behavior in the zebrafish organizer region
Authors: D'Amico Leonard A , Cooper Mark S
Published: April 2011

To determine the sequence of cell behaviors that is involved in the morphogenesis of the zebrafish organizer region, we have examined the dorsal marginal zone of vitally stained zebrafish embryos using time-lapse confocal microscopy. During the late-blastula stage, the zebrafish dorsal marginal zone segregates into several cellular domains, including a group of noninvoluting, highly endocytic marginal (NEM) cells. The NEM cell cluster, which lies in a superficial location of the dorsal marginal zone, is composed of both enveloping layer cells and one or two layers of underlying deep cells. The longitudinal position of this cellular domain accurately predicts the site of embryonic shield formation and occupies a homologous location to the organizer epithelium in Xenopus laevis. At the onset of gastrulation, deep cells underneath the superficial NEM cell domain undergo involution to form the nascent hypoblast of the embryonic shield. Deep cells within the NEM cell cluster, however, do not involute during early shield formation, but instead move in front of the blastoderm margin to form a loose mass of cells called forerunner cells. Forerunner cells coalesce into a wedge-shaped mass during late gastrulation and eventually become overlapped by the converging lateral lips of the germ ring. During early zebrafish tail elongation, most forerunner cells are incorporated into the epithelial lining of Kupffer's vesicle, a transient teleostean organ rudiment long thought to be an evolutionary vestige of the neurenteric canal. Owing to the location of NEM cells at the dorsal margin of blastula-stage embryos, as well as their early segregation from other deep cells, we hypothesized that NEM cells are specified by an early-acting dorsalizing signal. To test this possibility, we briefly treated early-blastula stage embryos with LiCl, an agent known to produce hyperdorsalized zebrafish embryos with varying degrees of expanded organizer tissue. In Li+-treated embryos, NEM cells appear either within expanded spatial domains or in ectopic locations, primarily within the marginal zone of the blastoderm. These results suggest that NEM cells represent a specific cell type that is specified by an early dorsal patterning pathway.
Characterization of heparin-binding endothelial mitogen(s) produced by the ovine endometrium during early pregnancy
Authors: Zheng Jing , Redmer Dale A , Killilea S Derek , Reynolds Lawrence P
Published: April 2011

To characterize mitogenic factors produced by ovine endometrium during early pregnancy, endometrial explant-conditioned media (ECM) were obtained from ewes on day 12, 18, 24, or 30 after mating. These ECM contained mitogenic activity for both endothelial and 3T3 cells across all days. The endothelial mitogenic activity was greatest on day 24, whereas mitogenic activity for 3T3 cells did not differ across days. By ultrafiltration, ion exchange, and heparin-affinity chromatography, the endothelial mitogenic activity was found to have a molecular mass greater than 100 kDa, to be anionic, and to be heparin binding, respectively. Three peaks of endothelial mitogenic activity were recovered from heparin-affinity chromatography. The major peak, H3, was mitogenic for endothelial but not for 3T3 cells. H3 was further purified, and the single peak of heparin-binding activity, designated H3b, represented a 681-fold purification of endothelial mitogenic activity from endometrial ECM. H3 and H3b were heat labile and trypsin sensitive, and their biological activity was heparin enhanced. The majority of the endothelial mitogenic activity was immunoneutralized by antibodies against acidic and basic FGF. Nevertheless, we were unable to detect bFGF in H3 or H3b by Western immunoblot analysis. Thus, in this study we have extended our previous observations and demonstrated that (i) during early pregnancy the ovine endometrium produces mitogenic activity for both endothelial and 3T3 cells, (ii) the endothelial mitogenic activity is greatest on day 24 after mating, which corresponds with the onset of endometrial vascular growth, and (iii ) the major endothelial mitogen has a high affinity for heparin, and although it is immunologically related to FGF, it differs from known FGF in its apparent molecular size and biological activities.Key words: heparin-binding growth factor, fibroblast growth factor, uterus, early pregnancy, ewe.