bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Relationship between Human and Animal Isolates ofCandida albicans
Authors: Edelmann Anke , Krüger Monika , Schmid Jan
Published: December 2005

AnalyzingCandida albicansisolates from different human and animal individuals by Ca3 fingerprinting, we obtained no evidence for host-specific genotypes and for the existence of species-specific lineages, even though a certain degree of separation between human and animal isolates was found. Therefore, animals could potentially serve as reservoirs for humanCandidainfection.
Use of Microelectronic Array Technology for Rapid Identification of Clinically Relevant Mycobacteria
Authors: Sanguinetti Maurizio , Novarese Linda , Posteraro Brunella , Ranno Stefania , De Carolis Elena , Pecorini Giovanni , Lucignano Barbara , Ardito Fausta , Fadda Giovanni
Published: December 2005

We developed a new method based on the Nanochip microelectronic array technology for identification of various clinically relevant mycobacterial species. PCR-amplified rRNA genes obtained from 270 positive Mycobacteria Growth Indicator Tube cultures were successfully tested by hybridizing them with species-selective probes, and the results agreed with those of conventional identification methods. The system is rapid and accurate and opens new perspectives in clinical diagnostics.
PCR Protocol for Specific Identification of
Candida nivariensis
, a Recently Described Pathogenic Yeast
Authors: Alcoba-Flórez Julia , del Pilar Arévalo María , González-Paredes F. Javier , Cano Josep , Guarro Josep , Pérez-Roth Eduardo , Méndez-Álvarez Sebastián
Published: December 2005

Candida nivariensis
is a recently described pathogenic yeast closely related to
Candida glabrata
. We developed a specific set of oligonucleotide primers based on the internal transcribed spacer regions of the rRNA gene for the rapid identification of
C. nivariensis.
PCR with these primers amplified a 206-bp amplicon from
C. nivariensis.
Comparison of the Avidity Index Method and the Serologic Testing Algorithm for Recent Human Immunodeficiency Virus (HIV) Seroconversion, Two Methods Using a Single Serum Sample for Identification of Recent HIV Infections
Authors: Martró Elisa , Suligoi Barbara , González Victoria , Bossi Vincenzo , Esteve Anna , Mei Joanne , Ausina Vicenç
Published: December 2005

A study was designed to compare an avidity index method to the serologic testing algorithm for recent human immunodeficiency virus (HIV) seroconversion (STARHS) for the detection of recent HIV infection. One hundred sixty HIV-positive sera were tested. Both techniques performed similarly in identifying recent infections, although STARHS tended to misclassify more individuals that had long-standing infection as being recently infected.
Shear behavior of reinforced concrete beams strengthened in flexure with bonded carbon fibre reinforced polymers laminates
Authors: Bencardino Francesco , Colotti Vincenzo , Spadea Giuseppe , Swamy Ramnath Narayan
Published: December 2005

The aim of this paper is to clarify the structural performance of reinforced concrete (RC) beams with weak or without any internal shear reinforcement and externally strengthened in flexure with carbon fibre reinforced polymer (CFRP) laminates, when subjected to a shear-dominant-loading regime. Seven RC beams were specifically designed, without and with an external anchorage system, which was carefully detailed to enhance the benefits of the strengthening laminate and counteract the destructive effects of shear forces. All the beams were identical in terms of their geometry, longitudinal internal reinforcement, and concrete strength but varied, to highlight the role of shear behavior, in terms of their internal and external shear reinforcement as well as in their loading test regime. The beams were tested under four-point bending and extensively instrumented to monitor strains, deflection, cracking, load carrying capacity, and failure modes. The structural response of the tested beams has, then, been critically analyzed in terms of deformability, strength, and failure processes that occur under a shear-dominant loading regime. It is shown that with a carefully designed anchorage system, a brittle behavior without yielding of tension steel reinforcement of a flexural strengthened beam can be transformed to a less brittle behavior with yielding of tension steel reinforcement and a well-defined enhancement of structural performance in terms of both deformation and strength. The results presented in this paper should enable engineers to counteract shear failure of externally strengthened beams with little or even no internal shear reinforcement.Key words: carbon fibre reinforced polymer, shear behavior, external flexural strengthening, structural performance.
Strategic analysis of the James Bay hydro-electric dispute in Canada
Authors: Ma Jing , Hipel Keith W , De Mitali
Published: December 2005

A strategic analysis of the James Bay conflict was carried out by using the graph model for conflict resolution. In 1971, Hydro-Québec, which is the third-largest electrical generating company of North America, began its large-scale hydroelectric projects in the James Bay area. Since the projects would significantly affect the living conditions of the native people and the environment around that region, worldwide debates were stimulated. A conflict model was developed in terms of the decision makers, their options, and their preferences for the situation existing as of January 2002, just prior to the signing of the final agreement. Subsequently, a stability analysis based on the calibrated model indicates that a possible resolution is that Hydro-Québec reduces the number of proposed power stations to appease the native people, who in turn would not initiate lawsuits. Sensitivity and hypergame analyses were also carried out to demonstrate the effects of preferences of decision makers on the final resolution. In practice, the modelling and analysis were implemented using the decision support system, GMCR II®. Key words: Hydroelectric, conflict resolution, decision support system, graph model, stability analysis, sensitivity analysis, hypergame analysis.
Early warning signs for distressed projects
Authors: Hanna Awad S , Gunduz Murat
Published: December 2005

There are many factors that can affect a project outcome such as management practices of the contractor, involvement and response of the owner, design change and design errors, and procurement delay. It is important for contractors and owners to be able to detect and rectify project stress as early as possible. This paper presents some factors, which if present would enable contractors and owners to predict the outcome of the project. To achieve this purpose, 116 projects were researched and analyzed. The probability of a project becoming distressed is calculated using a logistic regression model, which can be applied to a project early in the bidding process. The results of this paper are of value to owners, electrical and mechanical contractors, and construction managers.Key words: early warning signs, project outcome, bidding, logistic regression.
Modèle pluie–débit pour la simulation de courbes de débits classés sur des petits bassins non jaugés de l'Amazonie
Authors: Blanco C J , Secretan Y , Favre A-C , Slivitzky M
Published: December 2005

In Amazonia, hydroelectric power production has only been developed on large basins, which are the only ones that have been gauged. This excludes innumerable small catchments, for which only rainfall data are available. Therefore, the objective of the work presented in this paper is to develop a hydrological rainfall–runoff model to simulate flow duration curves for hydro power production planning. The model is based on a linear and time-invariant system (input–output). The impulse response of the system is calculated from the cross-spectral analysis between the rainfall and runoff series. This response is optimized successive approximations to minimize the root mean square of the error. The test catchment area has 7 years of rainfall and runoff data; 4 years are considered for the calibration and 3 years for the validation of the model. A sensitivity analysis of the model to the sample size is carried out to determine the shortest possible data period that produces results comparable to those of the model validation. Key words: model rainfall–runoff, small catchments, Amazonia, impulse response, sensitivity analysis.
Construction factors affecting as-built roughness of Portland cement concrete pavement construction
Authors: Lee Duk Gyoo
Published: December 2005

This paper investigates the significant construction factors affecting the as-built roughness of Portland cement concrete (PCC) pavement. The panel data analysis uses as-built roughness measurements and related construction factors for reconstructed, replaced, and resurfaced PCC pavement projects in Wisconsin from 1998 to 2002. Construction factors are divided into two categories in this analysis: (1) pavement characteristics and (2) contractor's quality-based performance. The analysis utilizes the fixed effects and random effects modeling techniques to identify the significant variables in the model. The research shows that the fixed effects model, of all proposed models, provides the best estimate on the basis of Akaike's information criterion (AIC). The results indicate that pavement characteristics and contractor's quality-based past performance significantly affect as-built roughness. The findings also show that geographic locations are strongly significant.Key words: panel (longitudinal) data analysis, as-built roughness, international roughness index (IRI), Akaike's information criterion (AIC), construction factor, Portland cement concrete (PCC) pavement, highway construction.
Évaluation de la remontée des vagues sur des barrages en milieu forestier créant des retenues modestes
Authors: Lavallée Daniel
Published: December 2005

Safe dam design, especially when the dam is likely to erode when submerged, must take into account wave surge. The lack of data for small structures built in a forest environment is a problem when assessing this surge. This paper proposes an approach to assess wave surge for these structures. The proposed approach is based on relationships developed by Saville et al. (1962) for inland lakes. An example to illustrate the application of this approach is discussed in the framework of the Quebec Dam Safety Regulation (Quebec Government 2002).Key words: dam design, dam safety.[Journal translation]
Application of dimensional analysis to estimation of ice-induced pressures on rigid vertical structures
Authors: Arunachalam A V.M
Published: December 2005

Dimensional analysis requirements for estimating ice-induced pressures during ice-structure interaction are identified, established, and discussed. Analysis of representative experimental results, based on these requirements, showed that for structures with constant surface slope, dimensionless ice-induced pressure (pe/ρiu2) is a function of four independent dimensionless parameters — aspect ratio (B/h), square of thickness Froude number (STFN = u2/gh), Cauchy number (CN = E/ρiu2), and a constitutive similarity condition (E/σ). It was found that (1) when STFN, CN, and E/σ were held constant, ice-induced pressure could be uniquely determined as a decreasing function of increasing B/h; (2) at any constant B/h, dimensionless ice-induced pressure decreased with increasing STFN, if CN was held constant; (3) when more than one independent dimensionless variables were simultaneously varied, ability to determine ice-induced pressure became increasingly difficult; and (4) for ice-structure interaction problems, when one independent dimensional variable was changed, it became difficult to keep some other independent dimensionless variables as constants because of interdependent nature of dimensionless variables defining the problem. This analysis is more useful in forming conclusions and insights on the influence of parameters defining ice-induced pressure and could be extended to develop predictive empirical equation for ice-induced pressures and deformation processes in ice-structure interaction problem.Key words: aspect ratio, dimensional analysis, failure modes, ice-structure interaction pressures, similarity theory.
Modélisation de l'évapotranspiration réelle à l'échelle régionale pour des bassins versants situés dans la forêt boréale
Authors: Pion Caroline , Leconte Robert , Rousselle Jean , Gagnon Sébastien
Published: December 2005

It is a known fact that evapotranspiration (ET) varies spatially and temporally and is affected by local and regional factors such as topography, soil properties, and vegetation. As the objective of this study is to model the spatial distribution of actual ET in a boreal ecosystem, a spatially distributed hydrological model employing the Priestley–Taylor approach was used. Spatial and temporal variations of the radiative fluxes at the study site were carefully modelled, as observed fluxes were scarce. Moreover, two modelling scenarios, each based on a different combination of input data sources, were examined. Observed flows were used to calibrate the hydrological model, and acceptable results were obtained. Results show that the modelling of actual ET is affected more by the spatially distributed precipitation than by radiative fluxes. This does not corroborate the experimental results of a previous study carried out over the same area on specific sites. However, the present study differs from the previous one, as the results are obtained at the regional scale.Key words: evapotranspiration, boreal forest, hydrological model, spatial and temporal heterogeneity.
The role of centromere-binding factor 3 (CBF3) in spindle stability, cytokinesis, and kinetochore attachment
Authors: Bouck David , Bloom Kerry
Published: December 2005

The spindle midzone is critical for spindle stability and cytokinesis. Chromosomal passenger proteins relocalize from chromosomes to the spindle midzone after anaphase onset. The recent localization of the inner-kinetochore, centromere-binding factor 3 (CBF3) complex to the spindle midzone in budding yeast has led to the discovery of novel functions for this complex in addition to its essential role at kinetochores. In G1/S cells, CBF3 components are detected along dynamic microtubules, where they can "search-and-capture" newly replicated centromeres. During anaphase, CBF3 is transported to the microtubule plus-ends of the spindle midzone. Consistent with this localization, cells containing a mutation in the CBF3 subunit Ndc10p show defects in spindle stability during anaphase. In addition, ndc10-1 cells show defects during cytokinesis, resulting in a defect in cell abscission. These results highlight the importance of midzone-targeted proteins in coordinating mitosis with cell division. Here we discuss these findings and explore the significance of CBF3 transport to microtubule plus-ends at the spindle midzone.Key words: spindle midzone, passenger protein, inner centromere protein (INCENP), microtubule plus-end.
Effect of forest harvest on soil temperature and water storage and movement patterns on Boreal Plain hillslopes
Authors: Whitson I R , Chanasyk D S , Prepas E E
Published: December 2005

Through its effect on vegetation, forest harvesting affects soil moisture storage, water movement processes, and soil temperature. The effects of harvest on water storage and movement patterns and on soil temperature during the snowmelt period were studied 3 years after harvest on hillslopes in northern Alberta, Canada. Measurements of soil water content, soil temperature, and bromide tracer concentrations were made at 11 pairs of forested and harvested plots, which are all dominated by Gray Luvisol soils but possess a range of topographic characteristics. Compared with forested sites, harvested sites were expected to have higher soil water content, display more interflow, and thaw earlier. Harvested sites were wetter on only one of four dates sampled, reflecting dry weather and rapid aspen regrowth. Greater loss and shallower penetration of bromide tracer in plots indicate that harvested sites had more interflow than forested sites. Despite a trend to higher temperatures, harvested sites did not thaw earlier than forested sites. Our inability to detect dramatic treatment effects reflects the need for large sample sizes for soil properties that display high local spatial and temporal variability. Key words: forest harvest, soil moisture, soil thaw, bromide, interflow, boreal.
Nitrogen removal in a small waste stabilization pond containing rock filters
Authors: Strang T J , Wareham D G
Published: December 2005

This study analyzes samples taken from 15 separate locations inside a small waste stabilization pond system in New Zealand. The system consisted of six ponds in series with rock filters installed between the final five ponds. The study aimed to determine the relative importance of the ponds and rock filters for nitrogen removal, for a typical effluent quality of 10 g/m3 total nitrogen during the 7 month study period. The results suggest that the most significant nitrogen removal occurred in the ponds rather than the rock filters. Comparison of removal rates to nitrogen accumulation in the sludge and estimates of ammonia volatilization suggest that the most likely mechanism for nitrogen removal is nitrification and denitrification. Possible sites for nitrification are explored in relation to theoretical principles and it is suggested that there may be adequate aerobic surface area on the banks of small-scale ponds to allow significant fixed film nitrogen reduction. A simple model is proposed that predicts nitrogen removal based on a constant removal rate proportional to the aerobic bank surface area. Key words: waste stabilization ponds, nitrogen, rock filters, nitrification, denitrification.
Acute molybdenum toxicity to rainbow trout and other fish
Authors: Davies Trevor D , Pickard Janet , Hall Ken J
Published: December 2005

Molybdenum is generally reported in the literature to be acutely lethal to various fish species at relatively high concentrations (70 to >2000 mg/L). The toxicity of molybdenum to fertilized rainbow trout eggs and alevins (EA), however, is controversial as different bioassays demonstrate a wide toxicity range (0.73 to >90 mg/L Mo). A duplication of a previous study using similar water chemistry along with the standard bioassay protocol demonstrated that molybdenum was not acutely toxic to the early life stages of rainbow trout over 32 d up to a maximum molybdenum concentration of 400 mg/L. An additional bioassay exposing early life stages of rainbow trout to a maximum molybdenum concentration of 1500 mg/L for 32 d did not cause sufficient mortality to allow an LC50 to be calculated. Key words: molybdenum, toxicity, bioassays, rainbow trout.
Wheat root colonization and nitrogenase activity byAzospirillumisolates from crop plants in Korea
Authors: Kim Chungwoo , Kecskés Mihály L , Deaker Rosalind J , Gilchrist Kate , New Peter B , Kennedy Ivan R , Kim Seunghwan , Sa Tongmin
Published: December 2005

Nitrogen-fixing bacteria were isolated from the rhizosphere of different crops of Korea. A total of 16 isolates were selected and characterized. Thirteen of the isolates produced characteristics similar to those of the reference strains of Azospirillum, and the remaining 3 isolates were found to be Enterobacter spp. The isolates could be categorized into 3 groups based on their ARDRA patterns, and the first 2 groups comprised Azospirillum brasilense and Azospirillum lipoferum. The acetylene reduction activity (ARA) of these isolates was determined for free cultures and in association with wheat roots. There was no correlation between pure culture and plant-associated nitrogenase activity of the different strains. The isolates that showed higher nitrogenase activities in association with wheat roots in each group were selected and sequenced. Isolates of Azospirillum brasilense CW301, Azospirillum brasilense CW903, and Azospirillum lipoferum CW1503 were selected to study colonization in association with wheat roots. We observed higher expression of β-galactosidase activity in A. brasilense strains than in A. lipoferum strains, which could be attributed to their higher population in association with wheat roots. All strains tested colonized and exhibited the strongest β-galactosidase activity at the sites of lateral roots emergence.Key words: Azospirillum, acetylene reduction activity, 16S rDNA, ARDRA patterns, lacZ fusion.
Expression of diphtheria toxin inStreptococcus mutansand induction of toxin-neutralizing antisera
Authors: Lee C W , Halperin S A , Morris A , Lee S F
Published: December 2005

The nontoxic full-length diphtheria toxin (DTX), fragment A (DTA), and fragment B (DTB) were each genetically fused to the major surface protein antigen P1 (SpaP) of Streptococcus mutans. Repeated attempts to express the recombinant DTX and DTB in the live oral vaccine candidate Streptococcus gordonii were unsuccessful, whereas DTA could be readily expressed in this bacterium. However, the recombinant DTX, DTB, and DTA could be expressed in the related oral bacterium S. mutans. Western blotting and enzyme-linked immunosorbant assay (ELISA) using anti-DTX and anti-P1 antibodies demonstrated the expression of the three fusion proteins in S. mutans. Mouse antisera raised against the recombinant S. mutans recognized the native DTX in Western immunoblotting. The antibodies raised against S. mutans expressing the recombinant DTX and DTA neutralized the cytotoxicity of the native toxin in a Vero cell assay, but the neutralization titers were relatively low. The potential of using S. gordonii as a live vaccine against diphtheria faces major challenges in the expression of DTX in this organism and in the induction of high-titer toxin-neutralizing antibodies.Key words: diphtheria toxin, Streptococcus mutans, Streptococcus gordonii.
Genetic and antigenic analysis ofBordetella pertussisisolates recovered from clinical cases in Ontario, Canada, before and after the introduction of the acellular pertussis vaccine
Authors: Tsang Raymond S.W , Sill Michelle L , Martin Irene E , Jamieson Frances
Published: December 2005

Sixty-eight Bordetella pertussis isolates (obtained between 1994 and 2004 from the province of Ontario in Canada) were compared by the following phenotypic and genetic analyses: serotyping; pulsed-field gel electrophoresis; and partial DNA sequence analysis of their pertactin, pertussis toxin, and fimbriae genes. Although temporal genetic variations were observed among the isolates, which is consistent with the current view that B. pertussis evolves over time, no specific antigenic or genetic type was detected in 48 isolates collected shortly after the introduction of the acellular pertussis vaccine. Further surveillance with clinical data and isolates collected periodically will be required to ensure that any genetic divergence that could affect vaccine efficacy will not be occurring.Key words: pertussis, genetic analysis, acellular vaccine.
Effect of nitric oxide on the growth ofChlamydophila pneumoniae
Authors: Carratelli Caterina Romano , Rizzo Antonietta , Paolillo Rossella , Catania Maria Rosaria , Catalanotti Piergiorgio , Rossano Fabio
Published: December 2005

Chlamydophila pneumoniae is an important human intracellular pathogen; however, the pathogenesis of C. pneumoniae infection is poorly understood and the immune control mechanism versus host cells is not completely known. The role of the nitric oxide (NO) synthase pathway in inhibiting the ability of C. pneumoniae to infect macrophage J774 cells and the ability of NO to damage isolated C. pneumoniae were investigated. Exposure of infected cultures to recombinant murine gamma interferon (MurIFN-γ) resulted in increased production of NO and reduced viability. Addition of 2-(N,N-diethylamino)-diazenolase-2-oxide before infection of J774 cells or during chlamydial cultivation released NO, both resulting in a reduction in the viability of C. pneumoniae in a dose-dependent way. These results indicate that immune control of chlamydial growth in murine macrophage cells may trigger a mechanism that includes NO release with effects on the multiplication of the microorganism, thus suggesting that NO may play a role in preventing the systemic spread of Chlamydia.Key words: Chlamydophila pneumoniae, J774 cells, NO.
Characterization of cytoplasmic fibril structures found in gliding cells of Saprospira sp.
Authors: Furusawa Gou , Yoshikawa Takeshi , Takano Yoshitaka , Mise Kazuyuki , Furusawa Iwao , Okuno Tetsuro , Sakata Taizo
Published: December 2005

The cytoplasmic fibril structures of Saprospira sp. strain SS98-5 grown on a low-nutrient agar medium were purified from cell lysates treated with Triton X-100 and were observed by electron microscopy to be about 7 nm in width and 200–300 nm in length. SDS–PAGE of the fibril structures exhibited a single protein band with a molecular mass of 61 kDa. A Saprospira cytoplasmic fibril protein (SCFP), which is a subunit of the fibril structures, was digested with trypsin to oligopeptides and analyzed for amino acid sequences. A partial nucleotide sequence of the SCFP gene was determined after PCR using primers designated from the amino acid sequences of the oligopeptides. SCFP gene including DNA fragments were detected by Southern hybridization using the PCR product for an SCFP gene as a probe and were cloned to determine whole nucleotide sequences. The SCFP gene indicated relatively higher similarity to conserved hypothetical phage tail sheath proteins. A Western immunoblotting analysis showed that SCFP was significantly expressed in gliding cells as compared with nongliding cells. The above findings with the previously reported results suggest that the cytoplasmic fibril structures are possibly related to the gliding motility of Saprospira sp. strain SS98-5.Key words: Saprospira, gliding motility, Saprospira cytoplasmic fibril protein (SCFP).
Spoligotype analysis ofMycobacterium bovisisolates from Northern México
Authors: Cobos-Marín Laura , Montes-Vargas Jesus , Zumarraga Martín , Cataldi Angel , Romano Maria Isabel , Estrada-Garcia Iris , Gonzalez-y-Merchand Jorge A
Published: December 2005

Bovine tuberculosis is still rife in Latin America, producing huge economic losses. There are very few studies of the way this disease is spread through this geographical region, particularly in countries that border those that are almost free of Mycobacterium bovis. In this work, we have analyzed the spacer oligonucleotide typing (spoligotype) patterns of M. bovis isolates from cattle at Ciudad Juárez, a Mexican city close to El Paso, Texas. Fifty-eight M. bovis isolates collected from a herd in Northern Mexico were studied by spoligotyping. Nine spoligotype patterns were observed in total. Two were predominant (SB0121 and SB0140) and accounted for 50% and 14% of the isolates, respectively. Six patterns were found to be already described in an international M. bovis spoligotype database, while the other three (SB0985, SB0986, and SB0987) were novel. Interestingly, none of the isolates corresponded to any other Mexican pattern previously reported. This is the first spoligotype analysis of M. bovis strains from a border city between Mexico and the United States. The necessity for further studies to formulate a better identification of M. bovis strains within, and its dissemination between, the two countries is discussed.Key words: Mycobacterium bovis, spoligotyping, bovine tuberculosis.
Mechanisms of airway smooth muscle relaxation during maturation
Authors: Wang Lu , Murphy Thomas M , Chitano Pasquale
Published: December 2005

Greater airway responsiveness in healthy juveniles is considered a factor in the higher asthma prevalence at a young age compared with adults. We have developed a guinea pig maturational model that utilizes tracheal strips from 1-week-, 3-week-, and 3-month-old guinea pigs to study the role of airway smooth muscle (ASM) in juvenile airway hyperresponsiveness. Because a reduced ability of ASM to spontaneously relax may contribute to airway hyperresponsiveness by maintaining bronchospasm and thus high airway resistance, we have employed this model to study ASM spontaneous relaxation during electrical field stimulation (EFS). Since relaxation during EFS had been neither described nor quantified during maturation, we developed new indices that allowed an appropriate comparison of the relaxing response from strips of different age animals. Using these indices we found that, whereas strips from adult animals relax to a level of tension similar to that found in the absence of stimulation, this ability to spontaneously relax is essentially absent in trachealis from infant animals. These results confirmed that maturation of ASM relaxation may play a role in juvenile airway hyperresponsiveness and that our maturational model is suitable to study the mechanisms regulating spontaneous relaxation in physiological conditions. We investigated the role of prostanoids in ASM relaxation and showed that cyclooxygenase inhibition increases relaxation in infant ASM to levels similar to adults. These results suggest that prostanoids regulate the ability of ASM to spontaneously relax, i.e., they reduce relaxation. We have produced preliminary data suggesting a maturational change in the level of prostanoids. Moreover, the possible action of acetylcholinesterase on maturation of ASM relaxation is discussed here on the basis of a preliminary study. We suggest that impairment of ASM relaxation likely contributes to increased airway responsiveness.Key words: acetylcholinesterase, airway responsiveness, asthma, ontogenesis, prostanoids.
Resting calcium influx in airway smooth muscle
Authors: Montaño Luis M , Bazán-Perkins Blanca
Published: December 2005

Plasma membrane Ca2+leak remains the most uncertain of the cellular Ca2+regulation pathways. During passive Ca2+influx in non-stimulated smooth muscle cells, basal activity of constitutive Ca2+channels seems to be involved. In vascular smooth muscle, the 3 following Ca2+entry pathways contribute to this phenomenon: (i) via voltage-dependent Ca2+channels, (ii) receptor gated Ca2+channels, and (iii) store operated Ca2+channels, although, in airway smooth muscle it seems only 2 passive Ca2+influx pathways are implicated, one sensitive to SKF 96365 (receptor gated Ca2+channels) and the other to Ni2+(store operated Ca2+channels). Resting Ca2+entry could provide a sufficient amount of Ca2+and contribute to resting intracellular Ca2+concentration ([Ca2+]i), maintenance of the resting membrane potential, myogenic tone, and sarcoplasmic reticulum-Ca2+refilling. However, further research, especially in airway smooth muscle, is required to better explore the physiological role of this passive Ca2+influx pathway as it could be involved in airway hyperresponsiveness.Key words: basal Ca2+entry, constitutive Ca2+channels, airway and vascular smooth muscle, SKF 96365, Ni2+.
Alterations in hypertensive arteries
Authors: Lee Robert M.K.W
Published: December 2005

Mentoring in academia is often carried out in an informal way depending on individuals and circumstances. I was quite fortunate to make the acquaintance of Professor E.E. Daniel when I was making a transition from my research in entomology to biomedical sciences. Here I recount some of that experience, and describe some of the lessons I have learned from this experience, as my tribute to Dr. Daniel on the occasion of his 80th birthday.Key words: vascular changes, morphometry, hypertension, vascular remodeling.
Prophylactic effects of an N- and L-type Ca2+ antagonist, cilnidipine, against cardiac hypertrophy and dysfunction in stroke-prone, spontaneously hypertensive rats
Authors: Takemori Kumiko , Ishida Hiroyuki , Dote Kensaku , Yamamoto Kazuo , Ito Hiroyuki
Published: December 2005

To clarify the beneficial effects of cilnidipine, an L- and N-type calcium channel blocker, which were clinically observed against diastolic dysfunction in hypertrophied hearts of hypertensive patients, we investigated the effects of cilnidipine on cardiac remodeling and enhanced gene expression in stroke-prone, spontaneously hypertensive rats in comparison with that of captopril, a well-known angiotensin-converting enzyme inhibitor, at threshold doses with little blood pressure lowering effect. The expression of type III collagen and β/α-myosin heavy chain as well as transforming growth factor-β, and basic fibroblast growth factor were suppressed by both treatments, indicating the prevention or amelioration of cardiac dysfunction. Such beneficial effects were much more intense with cilnidipine treatment than in captopril. These results indicate that Ca2+ is a key factor in the pathogenesis of cardiac remodeling in hypertension. One possible beneficial effect of cilnidipine in the prevention of cardiac dysfunction may be due to the decreased amount of growth factors such as transforming growth factor-β and basic fibroblast growth factor via direct action for Ca2+ influx and also via inhibition of local renin-angiotensin system in the myocardium.Key words: hypertension, cardiac hypertrophy, Ca2+-blocker, growth factor.
Mechanisms underlying the nitric oxide inhibitory effects in mouse ileal longitudinal muscle
Authors: Zizzo Maria Grazia , Mulè Flavia , Serio Rosa
Published: December 2005

We investigated the mechanisms involved in the nitric oxide (NO)-induced inhibitory effects on longitudinal smooth muscle of mouse ileum, using organ bath technique. Exogenously applied NO, delivered as sodium nitroprusside (SNP; 0.1–100 µmol/L) induced a concentration-dependent reduction of the ileal spontaneous contractions. 1H-[1,2,4]oxadiazolol[4,3,a]quinoxalin-1-one (ODQ; 1 µmol/L), a guanilyl cyclase inhibitor, reduced the SNP-induced effects. Tetraethylammonium chloride (20 mmol/L), a non-selective K+ channel blocker, and charybdotoxin (0.1 µmol/L), blocker of large conductance Ca2+-dependent K+ channels, significantly reduced SNP-induced inhibitory effects. In contrast, apamin (0.1 µmol/L), blocker of small conductance Ca2+-dependent K+ channels, was not able to affect the response to SNP. Ciclopiazonic acid (10 µmol/L) or thapsigargin (0.1 µmol/L), sarcoplasmatic reticulum Ca2+-ATPase inhibitors, decreased the SNP-inhibitory effects. Ryanodine (10 µmol/L), inhibitor of Ca2+ release from ryanodine-sensitive intracellular stores, significantly reduced the SNP inhibitory effects. The membrane permeable analogue of cGMP, 8-bromoguanosine 3′,5′-cyclic monophosphate (100 µmol/L), also reduced spontaneous mechanical activity, and its effect was antagonized by ryanodine. The present study suggests that NO causes inhibitory effects on longitudinal smooth muscle of mouse ileum through cGMP which in turn would activate the large conductance Ca2+-dependent K+ channels, via localized ryanodine-sensitive Ca2+ release.Key words: nitric oxide, mouse ileum, potassium channels, calcium stores.
Role of Cl–in cerebral vascular tone and expression of Na+-K+-2Cl–co-transporter after neonatal hypoxia-ischemia
Authors: Dai Yun , Tang Jiping , Zhang John H
Published: December 2005

Chloride (Cl–) efflux induces depolarization and contraction of vascular smooth muscle cells. In the basilar arteries from the New Zealand white rabbits, the role of Cl–flux in serotonin-induced contraction was demonstrated by (i) inhibition of Na+-K+-2Cl–co-transporter (NKCC1) to decreased Cl–influx with bumetanide; (ii) a disabled Cl–/HCO3– exchanger with bicarbonate free HEPES solution; (iii) blockade of Cl–channels using 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and indanyloxyacetic acid 94, R-(+)-methylindazone (R-(+)-IAA-94); and (iv) substitution of extracellular Cl–with methanesulfonate acid (113 mmol/L; Cl–, 10 mmol/L). In addition, the expression of NKCC1 in brain tissues after neonatal hypoxia-ischemia was examined at mRNA and protein levels using RT-PCR and Western blotting techniques. NKCC1 mRNA and protein expressions were increased at 24 and 48 h and returned to normal levels at 72 h after hypoxia insult when compared with the control littermates. In conclusion, Cl–efflux regulates cerebral circulation and the up-regulation of NKCC1 after neonatal hypoxia-ischemia may contribute to brain injury. Key words: serotonin, NCCK1, neonatal hypoxia.
Cells, cytokines and cellular immunity in the pathogenesis of fibroproliferative vasculopathies
Authors: Mitra Amit K , Del Core Michael G , Agrawal Devendra K
Published: December 2005

Atherosclerosis and restenosis are the result of vascular injury followed by an inflammatory and fibroproliferative response that involves a large number of growth factors, cytokines, and cellular elements. Platelet activation and leukocyte recruitment into the arterial intima play a crucial role, initiating a whole spectrum of reactions leading to vascular smooth muscle cell hyperplasia and intimal migration. The roles of macrophages and lymphocytes and mast cells as mediators of inflammation and immune response is discussed, as are the roles of growth factors and cytokines. New light on the 'old' problems will help us to devise newer and better therapeutic strategies to combat these clinical entities.Key words: atherosclerosis, cellular immunity, cytokines, growth factors, intimal hyperplasia, mast cells, restenosis, vasculopathies.
Regulation of myosin light chain phosphatase and pulmonary arterial relaxation
Authors: Dakshinamurti Shyamala
Published: December 2005

Neonatal circulatory transition is dependent upon tightly regulated pulmonary circuit relaxation. Persistent pulmonary hypertension (PPHN), a rapidly progressive disease of pulmonary arterial vasospasm and remodelling, may be characterized by pulmonary arterial myocyte relaxation failure. A key regulator of vascular tone is myocyte calcium sensitivity, determined by the relative stoichiometry of myosin light chain phosphorylation and dephosphorylation. We have recently reported downregulation of myosin light chain phosphatase activity in a hypoxic model of neonatal pulmonary hypertension. This review examines the recognized pathways of regulation governing myosin light chain phosphatase activity, including targeting subunit isoform switching, targeting unit phosphorylation and catalytic site inhibition. In light of the reviewed literature, further speculation is proposed on the potential contributions of these mechanisms to the pathophysiology of the perinatal pulmonary arterial relaxation defect in PPHN.Key words: smooth muscle, pulmonary hypertension, myosin light chain phosphatase, CPI-17, MYPT, review.
Beneficial and harmful effects of oscillatory mechanical strain on airway smooth muscle
Authors: Maksym Geoffrey N , Deng Linhong , Fairbank Nigel J , Lall C A , Connolly Sarah C
Published: December 2005

Airway smooth muscle (ASM) cells are constantly under mechanical strain as the lung cyclically expands and deflates, and this stretch is now known to modulate the contractile function of ASM. However, depending on the experimental conditions, stretch is either beneficial or harmful limiting or enhancing contractile force generation, respectively. Stretch caused by a deep inspiration is known to be beneficial in limiting or reversing airway constriction in healthy individuals, and oscillatory stretch lowers contractile force and stiffness or lengthens muscle in excised airway tissue strips. Stretch in ASM culture has generally been reported to cause increased contractile function through increases in proliferation, contractile protein content, and organization of the cell cytoskeleton. Recent evidence indicates the type of stretch is critically important. Growing cells on flexible membranes where stretch is non-uniform and anisotropic leads to pro-contractile changes, whereas uniform biaxial stretch causes the opposite effects. Furthermore, the role of contractile tone might be important in modulating the response to mechanical stretch in cultured cells. This report will review the contrasting evidence for modulation of contractile function of ASM, both in vivo and in vitro, and summarize the recent evidence that mechanical stress applied either acutely within 2 h or chronically over 11 d is a potent stimulus for cytoskeletal remodelling and stiffening. We will also point to new data suggesting that perhaps some of the difference in response to stretch might lie with one of the fundamental differences in the ASM environment in asthma and in culture — the presence of elevated contractile tone.Key words: length–tension, contraction, perturbed equilibrium of myosin binding, mechanical stress, cell phenotype, myosin light chain kinase, tone and relaxation, asthma.
Mechanical plasticity and contractile properties of airway smooth muscle
Authors: Fust Anita , Stephens Newman L
Published: December 2005

Smooth muscle has the unique ability to adapt easily and quickly to length changes without compromising its ability to generate force. This ability is referred to as mechanical plasticity and is now considered to be an important aspect of smooth muscle that affects both its contractile and relaxation behaviour. It is therefore important to incorporate knowledge of plasticity into further studies of smooth muscle behaviour. It is also important that future studies be focused on deciphering the mechanism of smooth muscle length adaptation and plasticity. This review outlines some of the proposed mechanisms determining plasticity. However, it should be said that there are other proposed mechanisms not touched upon here, which may be equally as important. This review also focuses on the relevance of smooth muscle plasticity in asthma, but it is important to remember that there are other places where smooth muscle plasticity may play an equally important role.Key words: mechanical plasticity, length adaptation, myosin conformation, asthma, hyperresponsivness.
Spring migration of Northern Pintails from California's Central Valley wintering area tracked with satellite telemetry: routes, timing, and destinations
Authors: Miller Michael R , Takekawa John Y , Fleskes Joseph P , Orthmeyer Dennis L , Casazza Michael L , Perry William M
Published: December 2005

We used satellite transmitters to track the 2000–2003 spring migrations of adult female Northern Pintails (Anas acuta L., 1758) from California's Central Valley, USA. PTT-tagged Pintails departed during late February to mid-March, and 77%–87% stopped first in the region of south-central Oregon, extreme northwestern Nevada, and northeastern California (SONEC). Subsequently, most Pintails used migration strategies characterized by the length of stay in SONEC and subsequent destinations: (i) extended stay in SONEC, migrated late April to early May directly to Alaska over the Pacific Ocean (7%–23% annually); (ii) same timing as in i, but flew to Alaska along the Pacific Coast using stopovers (0%–28% annually); (iii) moderate period in SONEC, migrated late March to mid-April directly primarily to southern Alberta in Prairie Canada (17%–39% annually), with many moving to northern Canada or Alaska; or (iv) short period in SONEC, migrated early to late March to Prairie Canada via stopovers primarily in southern Idaho and western Montana (32%–50% annually), with some moving to northern Canada or Alaska. Pintails that bypassed SONEC used these same strategies or moved easterly. Pintails modified migration strategies relative to record cold temperatures and wetland abundance in the mid-continent prairie region.
Effects of sex and body size on ectoparasite loads in the northern flying squirrel (Glaucomys sabrinus)
Authors: Perez-Orella Carolina , Schulte-Hostedde Albrecht I
Published: December 2005

Ectoparasites can have profoundly negative fitness consequences for host organisms. Sex differences in parasite load have been documented in many mammals, and have been attributed either to the allocation of energy to growth rather than the immune system in mammals exhibiting male-biased sexual size dimorphism or to the immunosuppressive qualities of testosterone. In addition, ectoparasites can have negative effects on body size and condition, as energy is allocated to the immune system rather than to growth and maintenance. Here, we used the northern flying squirrel (Glaucomys sabrinus (Shaw, 1801)) and its ectoparasites to test two predictions: (1) males are more heavily parasitized than females and (2) individuals with high ectoparasite loads will be in poorer condition and be smaller than individuals with low ectoparasite loads. Males were significantly more parasitized than females, and there was a nonsignificant trend for small males to be more parasitized than large males. Because the northern flying squirrel is not sexually dimorphic, the immunosuppressive qualities of testosterone may explain the sex differences in ectoparasite load. Ectoparasites may also influence skeletal growth rates, and males that are more susceptible to ectoparasites may simply be unable to allocate as much energy to growth and are thus structurally smaller.
Habitat occupancy patterns of a forest dwelling songbird: causes and consequences
Authors: Doran Patrick J , Holmes Richard T
Published: December 2005

We examined patterns of habitat use and reproductive performance of a migratory songbird, the black-throated blue warbler (Dendroica caerulescens (Gmelin, 1789)), within a 3160-ha forested landscape. We surveyed 371 sites over a 3-year period. Some sites were never occupied, while others were occupied for 1, 2, or 3 years. For these 3 years we found that warbler abundance increased with frequency of occupancy. Additionally, we found that (i) deciduousness and understory shrub density increased with frequency of occupancy; (ii) in 1 of 3 years, food abundance was higher at the most frequently occupied sites; and (iii) nest predators exhibited predator-specific abundance patterns across occupancy categories. We next used occupancy patterns documented in the first 3 years of the study to predict settlement, age structure, and reproductive performance at a subset of sites in the final year of the study. We found that males settled earlier in the breeding season at sites with a high frequency of occupancy. There were no differences in arrival times of females. Additionally, age structure did not vary for either males or females across sites with different occupancy levels. Although we found no difference in mean reproductive output across sites with different occupancy levels, over 50% of the young produced fledged from territories overlapping the high occupancy sites.
Common vole (Microtus arvalis) population sex ratio: biases and process variation
Authors: Bryja Josef , Nesvadbová Jiřina , Heroldová Marta , Jánová Eva , Losík Jan , Trebatická Lenka , Tkadlec Emil
Published: December 2005

Vole population sex ratio varies seasonally. However, population sex ratios have usually been estimated using naïve estimators that do not allow for biases owing to the sex difference in capture probabilities and movement distances (i.e., effective areas sampled). Here we aimed to advance the methodological approach, recognizing that there are two different classes of contributing mechanisms to the pattern which are best addressed separately: (1) those mechan isms imposing a systematic error (bias) in population estimates and (2) those generating the true process variation. Analyzing 7-year capture–recapture data in the common vole (Microtus arvalis (Pallas, 1778)), we quantified both types of biases and revealed that the bias owing to differential capture rates was often severe and less predictable, whereas that owing to differential effective areas was smaller and overestimated male numbers for most of the year. We demonstrated unambiguously that the unbiased population sex ratio indeed varies seasonally, with the males usually being more numerous over winter and spring. By testing predictions from two mechanistic hypotheses to explain the process variability, we found evidence for both the differential recruitment hypothesis and the differential survival hypothesis. From April–May to August, it was the females that were recruited more to the population and that had higher survival rates than males. We suggest that the seasonal variation in the population sex ratio is not merely a result of biasing mechanisms but an important population property driven by the joint effect of differential recruitment and differential survival between sexes.