bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of inducible nitric oxide synthase (iNOS) mRNA in target organs of lethal and non‐lethal strains of murine malaria
Authors: Nahrevanian Hossein , Dascombe Michael J. 
Published: December 2004

SUMMARY Nitric oxide (NO) is a putative mediator of the immunological and/or pathological responses to malaria, consequently it is a potential target for novel drug therapy. Numerous cell types increase expression of inducible nitric oxide synthase (iNOS) under inflammatory conditions, the most relevant stimuli being cytokines and endotoxins. In this study the expression of iNOS mRNA in several target organs (brain, liver, spleen) of malaria have been investigated in MF1 mice during lethal Plasmodium (P.) berghei and non‐lethal P. c. chabaudi infection. In P. berghei malaria, iNOS mRNA decreased in liver and was unchanged in spleen during the period of rising parasitaemia, but increased in both organs late in the infection, when parasitaemia was high and death imminent. In mice infected with P. c. chabaudi, spleen iNOS mRNA increased progressively throughout the early, peak and recovery periods of parasitaemia, but decreased in liver. Brain iNOS mRNA decreased in samples collected throughout the time courses of both infections. Hence it is evident that changes in iNOS mRNA in murine malaria depend upon the tissue, day of infection, degree of parasitaemia and strain of Plasmodium. These data indicate induction of iNOS mRNA in the spleen has a role in combating these strains of Plasmodium in MF1 mice. Failure to clear lethal P. berghei parasitaemia was associated with increased iNOS mRNA expression in the liver, which may contribute to the pathology of this malaria.
Cytoplasmic signalling pathways in alveolar macrophages involved in the production of nitric oxide after stimulation with excretory/secretory antigens of Toxocara canis
Authors: Espinoza Elsa , Pérez‐Arellano José Luis , Vicente Belén , Muro Antonio 
Published: December 2004

SUMMARY We studied the cytoplasmic signalling pathways involved in the generation of nitric oxide (NO) after stimulation with adult e

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cretory/secretory antigens (ESA) of Toxocara canis. The pathways of phospholipase A2 (PLA2) and phospholipase C (PLC) were considered as potentially involved in the synthesis of nitric oxide. We used inhibitors of these pathways at different levels. Several concentrations of lithium chloride, verapamil, TMB‐8 and staurosporine were used to inhibit the PLC pathway. Inhibition of the PLA2 pathway was attempted with mepacrine, diethylcarbamazine or meloxicam. Lithium chloride, verapamil and TMB‐8 reduced the production of NO induced by ESA in a concentration‐dependent manner. Regarding the PLA2 pathway, a range of concentrations of mepacrine greatly reduced the production of NO induced by ESA. Meloxicam inhibition was always higher than 50%. Diethylcarbamazine showed a dose‐dependent effect on the production of NO induced by the ESA. Our results suggest that both the PLC and the PLA2 pathways play an essential role in activating the production of macrophage NO triggered by the ESA of T. canis. This could indicate that NO production in our experimental conditions is due to both an increase of intracellular calcium and to the participation of the arachidonic acid cascade. The implications of these activations on the host–parasite relationship are discussed and compared with LPS‐stimulated macrophages.
Molecular and immunological characterization of the C‐terminal region of a new Echinococcus granulosus Heat Shock Protein 70
Authors: Ortona E. , Margutti P. , Delunardo F. , Vaccari S. , Riganò R. , Profumo E. , Buttari B. , Teggi A. , Siracusano A. 
Published: December 2004

SUMMARY By screening an expression library of Echinococcus granulosus with IgE from sera of patients with cystic echinococcosis (CE) and allergic reactions, we isolated the C‐terminal region of a new heat shock protein (HSP)70 of E. granulosus. The protein, named Eg2HSP70, has close homology with the C‐terminal region of Dermatophagoides farinae and human HSP70. We investigated the humoral and cell‐mediated immune responses to this antigen in patients with CE grouped according to the presence of allergic reactions. Immunoblotting detected total IgG, IgG4 and IgE specific to Eg2HSP70 (83% of sera contained IgG, 31% IgG4 and 57% IgE). No significant difference was found in immunoglobulin percentages according to the presence of allergic reactions. Immunoblotting inhibition showed that no IgG or IgE specific to Eg2HSP70 cross‐reacted with D. farinae or human HSP70. Eg2HSP70‐stimulated PBMC from 26 patients produced significantly greater amounts of TNF‐α, IFN‐γ, and IL‐10 than unstimulated cultures in all patients, irrespective of the presence of allergic reactions (P < 0·05). They also produced significantly greater amounts of IL‐4 than unstimulated cultures exclusively in patients with allergic reactions (P < 0·05). These findings show that Eg2HSP70 is a new antigenic molecule inducing both B and T cell responses.
Maternal temperature has different effects on the photoperiodic response and duration of larval diapause in blow fly (Calliphora vicina) strains collected at two latitudes
Authors: Mcwatters H. G. , Saunders D. S. 
Published: December 2004

Abstract.The blow fly Calliphora vicina Robineau‐Desvoidy (Diptera: Calliphoridae) has a wide distribution across northern and temperate Europe. It has a facultative, maternally‐induced larval diapause in response to short days. The photoperiodic response, measured at 15 and 20°C, of two populations was compared. A southern population (originating at 51° N) was sensitive to temperature at all daylengths; the incidence of diapause was greatly reduced at 20°C compared with 15°C. The photoperiodic response of a northern population (from 65° N) was sensitive to temperature only in long days; in short days (< 14 h of light) the response of this strain was identical at each temperature.Variation in parental photoperiod and temperature were found to affect the duration of larval diapause, indicating a role for maternal effects in diapause intensity as well as incidence. However, the between‐strain variation was greater than that within strains, indicating qualitative differences in diapause response. These differences may arise from the ecological conditions at the points of origin of the two strains. The northern strain from the harsher climate has a more intense diapause that follows a relatively temperature‐insensitive photoperiodic response. In contrast, the southern strain has a shallow diapause and its photoperiodic response may be overridden by the experience of concurrent high temperature.
Relationship between plant hydraulic and biochemical properties derived from a steady‐state coupled water and carbon transport model
Authors: KATUL G. , LEUNING R. , OREN R. 
Published: December 2004

ABSTRACTThere is growing evidence that plant stomata have evolved physiological controls to satisfy the demand for CO2by photosynthesis while regulating water losses by leaves in a manner that does not cause cavitation in the soil–root–xylem hydraulic system. Whether the hydraulic and biochemical properties of plants evolve independently or whether they are linked at a time scale relevant to plant stand development remains uncertain. To address this question, a steady‐state analytical model was developed in which supply of CO2via the stomata and biochemical demand for CO2are constrained by the balance between loss of water vapour from the leaf to the atmosphere and supply of water from the soil to the leaf. The model predicts the intercellular CO2concentration (Ci) for which the maximum demand for CO2is in equilibrium with the maximum hydraulically permissible supply of water through the soil–root–xylem system. The model was then tested at two forest stands in which simultaneous hydraulic, ecophysiological, and long‐term carbon isotope discrimination measurements were available. The model formulation reproduces analytically recent findings on the sensitivity of bulk stomatal conductance (gs) to vapour pressure deficit (D); namely,gs = gref(1 − m × lnD), wheremis a sensitivity parameter andgrefis a reference conductance defined atD = 1 kPa. An immediate outcome of the model is an explicit relationship between maximum carboxylation capacity (Vcmax) and soil–plant hydraulic properties. It is shown that this relationship is consistent with measurements reported for conifer and rain forest angiosperm species. The analytical model predicts a decline inVcmaxas the hydraulic capacity of the soil–root–xylem decreases with stand development or age.
Nitrogen use strategies of neotropical rainforest trees in threatened Atlantic Forest
Authors: AIDAR M. P. M. , SCHMIDT S. , MOSS G. , STEWART G. R. , JOLY C. A. 
Published: December 2004

ABSTRACTThe characteristics of nitrogen acquisition, transport and assimilation were investigated in species of an Atlantic Forest succession over calcareous soil in south‐eastern Brazil. Differences in behaviour were observed within the regeneration guilds. Pioneer species showed high leaf nitrogen contents, a high capacity to respond to increased soil nitrogen availability, a high capacity for leaf nitrate assimilation and were characterized by the transport of nitrate + asparagine. At the other end of the succession, late secondary species had low leaf nitrogen contents, little capacity to respond to increased soil nitrogen availability, low leaf nitrate assimilation and were active in the transport of asparagine + arginine. The characteristics of nitrogen nutrition in some early secondary species showed similarities to those of pioneer species whereas others more closely resembled late secondary species. Average leaf δ15N values increased along the successional gradient. The results indicate that the nitrogen metabolism characteristics of species may be an additional ecophysiological tool in classifying tropical forest tree species into ecological guilds, and may have implications for regeneration programmes in degraded areas.
Interactions in the uptake of amino acids, ammonium and nitrate ions in the Arctic salt‐marsh grass, Puccinellia phryganodes
Authors: HENRY H. A. L. , JEFFERIES R. L. 
Published: December 2004

ABSTRACTThe uptake of amino acids and inorganic nitrogen by roots of Puccinellia phryganodes was examined to assess the potential contribution of soluble organic nitrogen to plant nitrogen uptake in Arctic coastal marshes, where free amino acids constitute a substantial fraction of the soil‐soluble N pool. Short‐term excised root uptake experiments were performed using tillers grown hydroponically under controlled conditions in the field. The percentage reductions in ammonium uptake at moderate salinity (150 mm NaCl) compared with uptake at low salinity (50 mm NaCl) were double those of glycine, but glycine uptake was more adversely affected than ammonium uptake by low temperatures. Glycine uptake was higher at pH 5·7 than at pH 7·0 or 8·2. The glycine uptake was up‐regulated in response to glycine, whereas ammonium uptake was up‐regulated in response to ammonium starvation. Nitrate uptake was strongly down‐regulated when tillers were grown on either ammonium or glycine. In contrast to N‐starved roots, which absorbed ammonium ions more rapidly than glycine, the roots grown on glycine, ammonium and nitrate and not N‐starved prior to uptake absorbed glycine as rapidly as ammonium and nitrate ions combined. Overall, the results indicate that amino acids are probably an important source of nitrogen for P. phryganodes in Arctic coastal marshes.
Structural acclimation and radiation regime of silver fir (Abies albaMill.) shoots along a light gradient
Authors: CESCATTI A. , ZORER R. 
Published: December 2004

ABSTRACTShoot architecture has been investigated using the ratio of mean shoot silhouette area to total needle area () as a structural index of needle clumping in shoot space, and as the effective extinction coefficient of needle area. Althoughcan be used effectively for the prediction of canopy gap fraction, it does not provide information about the within‐shoot radiative regime. For this purpose, the estimation of three architectural properties of the shoots is required: needle area density, angular distribution and spatial aggregation. To estimate these features, we developed a method based on the inversion of a Markov three‐dimensional interception model. This approach is based on the turbid medium approximation for needle area in the shoot volume, and assumes an ellipsoidal angular distribution of the normals to the needle area. Observed shoot dimensions and silhouette areas for different vertical and azimuth angles (AS) are used as model inputs. The shape coefficient of the ellipsoidal distribution (c) and the Markov clumping index (λ0) are estimated by a least square procedure, in order to minimize the differences between model prediction and measurements ofAS. This methodology was applied to silver fir (Abies albaMill.) shoots collected in a mixed fir–beech–spruce forest in the Italian Alps. The model worked effectively over the entire range of shoot morphologies:cranged from 1 to 8 andλ0from 0·3 to 1 moving from the top to the base of the canopy. Finally, the shoot model was applied to reconstruct the within‐shoot light regime, and the potential of this technique in upscaling photosynthesis to the canopy level is discussed.
Effects of temperature on ascospore germination and penetration of oilseed rape (Brassica napus) leaves by A‐ or B‐groupLeptosphaeria maculans(phoma stem canker)
Authors: Huang Y. J. , Toscano‐Underwood C. , Fitt B. D. L. , Hu X. J. , Hall A. M. 
Published: December 2004

Ascospores of both A‐group and B‐groupLeptosphaeria maculansgerminated at temperatures from 5 to 20°C on leaves of oilseed rape. Germination of ascospores of both groups started 2 h after inoculation and percentage germination reached its maximum about 14 h after inoculation at all temperatures. Both the percentage of A‐/B‐group ascospores that had germinated after 24 h incubation and germ tube length increased with increasing temperature from 5 to 20°C. Germ tubes from B‐group ascospores were longer than those from A‐group ascospores at all temperatures, with the greatest difference at 20°C. Hyphae from ascospores of both groups penetrated the leaves predominantly through stomata, at temperatures from 5 to 20°C. A‐group ascospores produced highly branched hyphae that grew tortuously, whereas B‐group ascospores produced long, straight hyphae. The percentage of germinated ascospores that penetrated stomata increased with increasing temperature from 5 to 20°C and was greater for A‐group than for B‐groupL. maculansafter 40 h incubation.
Causal Inference with Generalized Structural Mean Models
Authors: Vansteelandt S. , Goetghebeur E. 
Published: December 2004

SummaryWe estimate cause–effect relationships in empirical research where exposures are not completely controlled, as in observational studies or with patient non-compliance and self-selected treatment switches in randomized clinical trials. Additive and multiplicative structural mean models have proved useful for this but suffer from the classical limitations of linear and log-linear models when accommodating binary data. We propose the generalized structural mean model to overcome these limitations. This is a semiparametric two-stage model which extends the structural mean model to handle non-linear average exposure effects. The first-stage structural model describes the causal effect of received exposure by contrasting the means of observed and potential exposure-free outcomes in exposed subsets of the population. For identification of the structural parameters, a second stage ‘nuisance’ model is introduced. This takes the form of a classical association model for expected outcomes given observed exposure. Under the model, we derive estimating equations which yield consistent, asymptotically normal and efficient estimators of the structural effects. We examine their robustness to model misspecification and construct robust estimators in the absence of any exposure effect. The double-logistic structural mean model is developed in more detail to estimate the effect of observed exposure on the success of treatment in a randomized controlled blood pressure reduction trial with self-selected non-compliance.
An Estimating Equation for Parametric Shared Frailty Models with Marginal Additive Hazards
Authors: Pipper Christian Bressen , Martinussen Torben 
Published: December 2004

SummaryMultivariate failure time data arise when data consist of clusters in which the failure times may be dependent. A popular approach to such data is the marginal proportional hazards model with estimation under the working independence assumption. In some contexts, however, it may be more reasonable to use the marginal additive hazards model. We derive asymptotic properties of the Lin and Ying estimators for the marginal additive hazards model for multivariate failure time data. Furthermore we suggest estimating equations for the regression parameters and association parameters in parametric shared frailty models with marginal additive hazards by using the Lin and Ying estimators. We give the large sample properties of the estimators arising from these estimating equations and investigate their small sample properties by Monte Carlo simulation. A real example is provided for illustration.
Detecting Dependence Between Marks and Locations of Marked Point Processes
Authors: Schlather Martin , Ribeiro Paulo J. , Diggle Peter J. 
Published: December 2004

SummaryWe introduce two characteristics for stationary and isotropic marked point proces- ses, E(h) and V(h), and describe their use in investigating mark–point interactions. These quantities are functions of the interpoint distance h and denote the conditional expectation and the conditional variance of a mark respectively, given that there is a further point of the process a distance h away. We present tests based on E and V for the hypothesis that the values of the marks can be modelled by a random field which is independent of the unmarked point process. We apply the methods to two data sets in forestry.
Stepwise Likelihood Ratio Statistics in Sequential Studies
Authors: Huang Wenzheng 
Published: December 2004

SummaryIt is well known that in a sequential study the probability that the likelihood ratio for a simple alternative hypothesis H1versus a simple null hypothesis H0 will ever be greater than a positive constant c will not exceed 1/c under H0. However, for a composite alternative hypothesis, this bound of 1/c will no longer hold when a generalized likelihood ratio statistic is used. We consider a stepwise likelihood ratio statistic which, for each new observation, is updated by cumulatively multiplying the ratio of the conditional likelihoods for the composite alternative hypothesis evaluated at an estimate of the parameter obtained from the preceding observations versus the simple null hypothesis. We show that, under the null hypothesis, the probability that this stepwise likelihood ratio will ever be greater than c will not exceed 1/c. In contrast, under the composite alternative hypothesis, this ratio will generally converge in probability to ∞. These results suggest that a stepwise likelihood ratio statistic can be useful in a sequential study for testing a composite alternative versus a simple null hypothesis. For illustration, we conduct two simulation studies, one for a normal response and one for an exponential response, to compare the performance of a sequential test based on a stepwise likelihood ratio statistic with a constant boundary versus some existing approaches.
Intraspecific olive diversity assessed with AFLP
Authors: Sanz‐Cortés F. , Parfitt D. E. , Romero C. , Struss D. , Llacer G. , Badenes M. L. 
Published: December 2004

AbstractAmplified fragment length polymorphism (AFLP) was used to study diversity within and among Spanish olive varieties. A high degree of diversity was found among the varieties present in each growing region. Olive oil production and quality relies on appropriate cultivar selection as well as good orchard management. Production based only on a few superior cultivars would result in improved yield, oil quality, and production management. Amplified fragment length polymorphism were evaluated as a tool to identify the intraspecific and intravarietal diversity of olive. Amplified fragment length polymorphism analysis of 38 accessions belonging to 10 cultivars using six primer combinations produced 106 polymorphic bands. Results were analyzed for similarity among accessions via unweighted pair‐group means cluster analysis, resulting in 10 clusters corresponding to named variety designations. Similarity among varieties ranged from 0.60 to 0.72. Diversity within varieties was identified. Similarity within named varieties (accessions with the same varietal name) ranged from 0.75 to 0.96. Differences in several markers were found among 34 accessions. Intravarietal diversity was shown to exist within the Spanish olive varieties grown in the region surrounding Valencia.
Genetic analysis of tissue culture traits in barley cv. ‘Lenins’
Authors: Rikiishi K. , Matsuura T. , Maekawa M. , Noda K. , Takeda K. 
Published: December 2004

AbstractThe barley cultivar ‘Lenins’ was found to be a genotype showing high shoot regeneration ability in cultures derived from immature embryos. Five cultivars different from ‘Lenins’ in shoot regeneration ability were reciprocally crossed with ‘Lenins’ and the inheritance of tissue culture traits was investigated. F2 plants showed continuous distributions in callus growth and percentage of shoot regeneration, suggesting that these traits were controlled by polygenes. The F2 population, derived from a cross between ‘Lenins’ and ‘6721′, showed a monogenic segregation for the number of regenerated shoots, and the segregation ratio fitted 1:2:1. Tissue culture traits of ‘Lenins’ were controlled by several genes, whereas the number of regenerated shoots related to the efficiency of shoot regeneration is controlled by one major gene.
Barley lines showing prominent high green shoot regeneration in cultures derived from immature embryos
Authors: Rikiishi K. , Matsuura T. , Maekawa M. , Noda K. , Takeda K. 
Published: December 2004

AbstractEighty‐four cultivars of barley (Hordeum vulgare) and 95 wild strains (82 of H. spontaneum and 13 of H. agriocrithon) were surveyed for the production of callus, callus growth, and shoot regeneration in cultures derived from immature embryos. All cultivars except for ‘Turkey 381′, induced calli from more than 90% of embryos. On the other hand, the wild lines showed a large variation in the percentage of callus induction from 0 to 100%. Among the cultivars, those with the brittle rachis genotype, bt Bt2, on chromosome 3H, regenerated shoots with a significantly higher percentage than the cultivars with the Bt bt2 genotype. Green shoots were produced in a higher ratio (0.84) in the cultivars than in the wild lines (0.52). Among the lines examined,‘Lenins’ regenerated shoots efficiently (90.4%) and produced the highest number of calli with green shoots per embryo (4.77) followed by ‘Golden Promise’ (3.15). Examination of callus growth and shoot regeneration from embryos at different developmental stages revealed that scutellum development affected the quantity and quality of callus and shoot regeneration.