bluuebunny/crossref_metadata_2025 huggingface dataset:
Time vs. light: a potentially useable light sum hybrid model to represent the juvenile growth of Douglas-fir subject to varying levels of competition
Authors: Mason E. G. , Rose R. W. , Rosner L. S.
Published: July 2007

Substitution of potential useable light sum for time in a commonly used mensurational equation resulted in a better fit to data from a complex vegetation management experiment. The experiment involved Douglas-fir ( Pseudotsuga menzeisii (Mirb.) Franco) as a crop species and a variety of competing species. Site occupancy by competing vegetation varied with time because control operations were intermittently either included or excluded from treatments over a period of 4 years. There were four randomized complete blocks of eight competition control treatments. Potentially useable light sum was estimated using measurements of radiation from a meteorological station that were modified by coefficients representing the ability of the crop plants to use light with varying soil water, vapour pressure deficit, and temperature. Light sums were further reduced by estimated competition for light from competing vegetation. Fits of the model to individual plots within the experiment yielded coefficients that did not differ significantly between competition control treatments, suggesting that the model accounted for significant variations in growth resource availability between treatments. Potentially useable light sum equations provide an integrated link between traditional mensurational modeling and ecophysiological modeling.
A carbon-based method for estimating the wetness of forest surface soil horizons
Authors: Ross Donald S.
Published: July 2007

The degree of wetness in forest surface soils has an effect on chemical and biological processes but is not easily measured. The high spatial variability in carbon (C) concentration creates high variability in water-holding capacity, and gravimetric water content is not informative. Local hydrology can create patchiness in soil moisture, with saturated soils often found near well-drained ones. When sampling to measure such factors as nitrification potential, it would be advantageous to have a simple metric that reflects the relative wetness of the soil. The relationship between C concentration (range 51.5–520.8 g·kg–1) and gravimetric water content was found to be linear for a set of 113 H- and A-horizon samples assumed to be at field capacity. The wetness ratio is defined as the actual water content of a sample divided by the water content predicted by the least squares regression equation based on C concentration (soil water content (kg·kg–1) = 0.080 + 0.0057 soil C concentration (g·kg–1)). Soil moisture retention curves were developed for a small number of samples in the range of 0 to about –10 kPa and showed that the equation predicted that water would be held at relatively high potential. In samples taken from 10 watersheds in the northeastern USA, wetness ratios between 1.25 and 3.1 were associated with soils identified in the field as ranging from wet to boglike. A median ratio of 0.49 was found in a watershed sampled after an extended dry period. At the Sleepers River Research Watershed, high wetness ratios were associated with a high soil calcium concentration, presumably from enriched groundwater. The ratio should be a useful measurement in watershed studies.
Weighted estimators for forest inventory mapped plots
Authors: Van Deusen Paul C.
Published: July 2007

Forest inventory data are often summarized in tabular format where rows and columns represent levels of categorical variables. It is generally desirable to constrain tables based on different categories to sum to common totals. It may also be desirable to develop a system that incorporates stratification. Weights can be assigned to inventory plots to achieve these goals with weighted estimators. The justification for weighting is presented here along with approaches for defining reasonable weights. A weighted estimator is developed to constrain tables derived from mapped plot data to add to common totals.
Scale-dependent microhabitat selection by threatened mountain caribou (Rangifer tarandus caribou) in cedar–hemlock forests during winter
Authors: Serrouya Robert , McLellan Bruce N. , Flaa John P.
Published: July 2007

Mountain caribou, an endangered ecotype of woodland caribou ( Rangifer tarandus caribou Gmelin, 1788), live in late-successional coniferous forests where they depend largely on arboreal lichens as winter forage. While radio-telemetry has been used to understand caribou habitat selection patterns at broad scales among and within populations, here we use snow-trailing in old cedar–hemlock forests between 1992 and 2003 to study three finer scales of habitat selection: (1) forest stands used for foraging from available forest stands (among-stand selection), (2) foraging paths within selected stands relative to random paths within those same stands (within-stand selection), and (3) feeding items along foraging paths. Relative to stands that were available on the landscape, caribou selected stands with more windthrown trees and standing snags. Within stands, caribou selected paths that had more live trees, snags with branches and bark, and trees with larger diameters. All of these habitat attributes facilitate access to arboreal lichen. Of the potential forage items encountered along foraging paths, caribou preferred to feed on windthrown trees, lichen litterfall and falsebox ( Paxistima myrsinites (Pursh.) Raf.). Our results go beyond telemetry studies by revealing that not all old forests are of equal value to mountain caribou. Prioritization among old stands will help refine conservation measures, as will silvicultural systems that incorporate key habitat attributes to maintain winter habitat in low-elevation cedar–hemlock ecosystems.
Estimation of the diameter distribution of a stand marked for cutting using finite mixtures
Authors: Nordhausen Klaus , Nummi Tapio
Published: July 2007

The aim of this paper is to find a parametric model for the diameter distribution when a sample of trees in a stand is measured by a harvester. It has important applications prior to and during harvesting for the assessment of the production potential of the stand marked for cutting. We apply the finite mixture models for tree species separately. Our data consist of six real forest stands measured in Finland. Our results showed that, for practical implementation, a three-component Lognormal mixture distribution seemed to be a reasonable choice. The subsample analysis indicated that, for certain stands, a sample size as low as 100 provides a quite good average fit for the chosen three-component mixture distribution, but for other stands, the sample size should be much larger.
Genetic variation in wood shrinkage and its correlations with tree growth and wood density of Calycophyllum spruceanum at an early age in the Peruvian Amazon
Authors: Sotelo Montes Carmen , Beaulieu Jean , Hernández Roger E.
Published: July 2007

Calycophyllum spruceanum (Benth.) Hook. f. ex Shum. is an important timber tree species in the Peruvian Amazon Basin. Farmers and industry use wood from young trees of this species, so tree breeders should investigate genetic variation in juvenile wood properties to verify whether they can be improved. A previous study using the same provenance/progeny test showed that there was significant genetic variation in tree growth and wood density, that heritability was higher for density than for growth, and that density and growth were positively correlated at 39 months. This paper presents results for wood shrinkage at 39 months and their correlations with tree growth and wood density. Data were collected on thinned trees. Shrinkage values were relatively low when considering wood density of this species. There was significant genetic variation in wood shrinkage due to families within provenances and, in some cases, due to provenances. Heritability estimates were moderately high for linear and volumetric shrinkage (0.37–0.50) and lower for the tangential/radial shrinkage ratio (0.21–0.29) across zones. The genetic correlations that were considered significant ranged from 0.30 to 0.80. In general, genetic correlations suggest that selection of faster-growing trees with higher wood density would result in wood with greater shrinkage and a larger tangential/radial shrinkage ratio.
Overturning resistance of western redcedar and western hemlock in mixed-species stands in coastal British Columbia
Authors: Byrne Kenneth E. , Mitchell Stephen J.
Published: July 2007

Specific information about the applied forces that cause trees to fail is required to validate mechanistic models of windthrow in different forest types. Static tree-pulling tests were conducted to examine the overturning resistance of western redcedar ( Thuja plicata Donn ex D. Don) and western hemlock ( Tsuga heterophylla (Raf.) Sarg.) in a mixed species second-growth stand in coastal British Columbia. Although widely used, tree-pulling techniques are not standardized. Data from three inclinometers were used to estimate stem deflection, which was found to increase with tree slenderness. Differing methods of fitting stem curvature had a small effect on estimates of self-loading at failure. The distance of the pivot point from the centre of the stem base increased with tree diameter. Accounting for the correct self-loading at failure produced a small difference in the overall turning moment regressions but did not improve the fit of these regressions. However, this difference increased with tree size and warrants consideration in future tree-pulling tests with large or plate-rooted trees. The stem mass – overturning resistance relationship had the best fit and was not significantly different for these species in spite of their differences in wood density and stem form.
An assessment of dead wood patterns and their relationships with biophysical characteristics in two landscapes with different disturbance histories in coastal Oregon, USA
Authors: Kennedy Rebecca S.H. , Spies Thomas A.
Published: July 2007

Understanding the relative importance of landscape history, topography, vegetation, and climate to dead wood patterns is important for assessing pattern–process relationships related to dead wood and associated biodiversity. We sampled dead wood at four topographic positions in two landscapes (1400–2100 km2) that experienced different wildfire and salvage histories in coastal Oregon. Study objectives were to (i) determine whether and how the landscapes differed in dead wood amounts and characteristics and (ii) evaluate relationships between dead wood characteristics and potentially related biophysical variables associated with historical and current vegetation, topography, climate, soils, and ecoregion. Despite differences in history, the two landscapes differed little in total dead wood volume; however, they differed in dead wood volume by structural type, decay class, and source (legacy/nonlegacy). Dead wood varied by topographic position, and topography was of greatest importance compared with other factors. In this mountainous region, upper topographic positions may be source areas for dead wood and riparian areas and streams sinks for dead wood. Climate explained more variance in dead wood in the landscape that burned earlier and was not salvaged. Landscape-scale patterns of dead wood are evident in landscapes with different disturbance histories and despite finer-scale variation in topography, vegetation, and other biophysical attributes.
The influence of white pine blister rust on seed dispersal in whitebark pine
Authors: McKinney Shawn T. , Tomback Diana F.
Published: July 2007

We tested the hypotheses that white pine blister rust ( Cronartium ribicola J.C. Fisch.) damage in whitebark pine ( Pinus albicaulis Engelm.) stands leads to reduced (1) seed cone density, (2) predispersal seed survival, and (3) likelihood of Clark’s Nutcracker ( Nucifraga columbiana (Wilson, 1811)) seed dispersal. We gathered data from two sets of paired forest sites in the Bitterroot Mountains of eastern Idaho and western Montana that were similar in topography, canopy structure, tree species composition, and successional stage, but differed in rust infection level, crown kill, and tree mortality. We counted initial (mid-July) and final (late August) seed cones, observed vertebrate seed predator activity, and documented nutcracker seed dispersal in study sites in 2001 and 2002. High-rust sites had higher rates of seed predation relative to cone abundance, lower predispersal seed survival, and fewer observations of nutcracker seed dispersal than paired low-rust sites. These findings suggest that as blister-rust-induced damage increases within stands in the Bitterroot Mountains, the likelihood of nutcracker seed dispersal decreases. We propose that whitebark pine in heavily rust-damaged forests may not self-regenerate and would therefore require planting of seeds or seedlings from genetically rust-resistant trees.
Soil and foliar chemistry associated with potassium deficiency in Pinus radiata
Authors: Smethurst Philip , Knowles Andrew , Churchill Keith , Wilkinson Ann , Lyons Arthur
Published: July 2007

We required an improved understanding of K deficiency and diagnosis in Pinus radiata D. Don (radiata pine). A rapid growth response to K fertilization (100 kg·ha–1) in the presence of weed control confirmed K deficiency in a 2-year-old stand. Tree growth did not respond to N fertilization, and weed control alone appeared insufficient to maximize tree growth. Temporal patterns in visual symptoms of K deficiency suggested they were worst at the end of a drought, and improved after several months of above-average rainfall that coincided with an increase in soil temperature. Soil chemistry generally responded predictably to fertilization, but K fertilization increased soil solution Ca and Mg concentrations without changing exchangeable concentrations. With weed control, a doubling of stem growth response to K fertilizer was associated with a 270% increase in soil solution K (natural variation amongst control plots), 51% increase in exchangeable K, and 39% increase in foliar K. Relationships between seedling growth and hydroponic concentrations of K were consistent with the incidence of K deficiency in the field; predicting these deficiencies using soil exchangeable concentrations was less clear. This study advances the interpretation of soil and foliar chemistry in relation to K and Mg deficiency in P. radiata.
A NOTE ON COULOMB SCATTERING AMPLITUDE
Authors: AHMED ZAFAR
Published: July 2007

The summation of the partial wave series for Coulomb scattering amplitude, fC(θ) is usually avoided because the series is oscillatorily and divergent. Instead, fC(θ) is generally obtained by solving the Schrödinger equation in parabolic cylindrical coordinates which is not a general method. Here, we show that a reconstructed series, (1- cos θ)2fC(θ), is both convergent and analytically summable.
VIOLATION OF STRONG ENERGY CONDITION IN EFFECTIVE LOOP QUANTUM COSMOLOGY
Authors: XIONG HUA-HUI , ZHU JIAN-YANG
Published: July 2007

In loop quantum cosmology nonperturbative modification to a scalar matter field at short scales implies inflation which also means a violation of the strong energy condition. In the framework of effective Hamiltonian we discuss the issue of violation of the strong energy condition in the presence of quantum geometry potential. It is shown that the appearance of quantum geometry potential strengthens the violation of the strong energy condition in small volume regions. In the small volume regions superinflation can easily happen. Furthermore, when the evolution of the universe approaches the bounce scale, this trend of violating the strong energy condition can be greatly amplified.
A COMPREHENSIVE ANALYSIS OF THE PION–PHOTON TRANSITION FORM FACTOR IN THE LEADING ORDER APPROXIMATION
Authors: HUANG TAO , WU XING-GANG
Published: July 2007

We perform a comprehensive analysis of the pion–photon transition form factor Fπγ(Q2) involving the transverse momentum corrections in the leading order approximation with the present CLEO experimental data, in which the contributions beyond the leading Fock state have been taken into consideration. As is well known, the leading Fock-state contribution dominates of Fπγ(Q2) at large momentum transfer (Q2) region. One should include the contributions beyond the leading Fock state in small Q2 region. In this paper, we construct a phenomenological expression to estimate the contributions beyond the leading Fock state based on its asymptotic behavior at Q2→0. Our present theoretical results agree well with the experimental data in the whole Q2 region. Then, we extract some useful information of the pionic leading twist-2 distribution amplitude (DA) by comparing our results of Fπγ(Q2) with the CLEO data. By taking best fit, we have the distribution amplitude moments, [Formula: see text] and all of higher moments, which are closed to the asymptotic-like behavior of the pion wave function.
TWO-CENTER PROBLEM FOR THE DIRAC EQUATION WITH A COULOMB AND SCALAR POTENTIAL
Authors: BONDARCHUK V. V. , SHVAB I. M. , KATERNOGA A. V.
Published: July 2007

The ground state wave function and the energy term of a relativistic electron moving in the field of two fixed centers, when interaction of this particle with centers is described by two Coulomb and two Coulomb-like scalar potentials are calculated analytically by the LCAO method. Dependence of electron binding energy from value of scalar coupling constant was investigated using obtained analytic results.
CHERENKOV GLUONS (PREDICTIONS AND PROPOSALS)
Authors: DREMIN I. M.
Published: July 2007

The coherent hadron production analogous to Cherenkov radiation of photons gives rise to the ring-like events. Being projected on the ring diameter they produce the two-bump structure recently observed for the away-side jets at RHIC. The position of the peaks and their height determine such properties of the hadronic medium as its nuclear refractive index, the parton density, the free path length and the energy loss of Cherenkov gluons. Cherenkov gluons may be responsible for the asymmetry of dilepton mass spectra near ρ-meson observed in experiment. Beside comparatively low energy gluons observed at RHIC, there could be high energy gluons at LHC, related to the high energy region of positive real part of the forward scattering amplitude and possessing different characteristics. This would allow to scan (x, Q2)-plane determining the parton densities in its various regions.
Regional Caledonian structure within an oblique convergence zone, Dronning Louise Land, NE Greenland
Authors: STRACHAN R. A. , HOLDSWORTH R. E. , FRIDERICHSEN J. D. , JEPSEN H. F.
Published: July 2007

Dronning Louise Land includes a well-exposed part of the marginal thrust zone that defines the western limit of the NE Greenland Caledonides. The autochthonous Laurentian craton west of the thrust zone comprises an orthogneissic basement which is overlain unconformably by sedimentary rocks of the Mid-Proterozoic Trekant Series and theSkolithos-bearing Zebra Series of probable latest Precambrian-early Cambrian age. This cover-basement sequence becomes strongly folded towards the thrust zone. The zone is characterized by numerous east-dipping thrust slices of mylonitized basement and metamorphosed equivalents of the Trekant and Zebra Series. Allochthonous rocks above the thrust zone are mainly heterogeneously reworked basement gneisses which in areas of low strain are similar in character and pre-Caledonian history to those of the foreland. Synclinal inliers of metasedimentary cover rocks include sequences correlated with the Zebra Series. The Caledonian thrust zone in NE Greenland does not therefore separate markedly different geological terrains. The orogen-parallel, sinistral Storstrømmen shear zone lies east of Dronning Louise Land, and it appears that the Caledonian deformation pattern in this part of the orogen is the product of sinistral transpression. The sequence of structures can be interpreted in terms of early low-angle sinistral strike-slip, followed by partitioned sinistral strike-slip and oblique thrusting, and later more or less orthogonal thrusting and folding. This sequence may indicate a significant component of oblique collision between Lauren tia and Baltica during closure of the Iapetus Ocean.
Structure and kinematics of a sinistral transpressive suture between the Ossa–Morena and the South Portuguese Zones, South Iberian Massif
Authors: CRESPO-BLANC A.
Published: July 2007

The Ossa–Morena Zone and the South Portuguese Zone represent the southernmost Hercynian domains of the Iberian Massif. Lithostratigraphic, petrographic and structural differences exist between both zones. The boundary between the Ossa–Morena and the South Portuguese Zones is marked by a narrow belt of amphibolites of tholeiitic affinity and related oceanic sequences, the Beja–Acebuches ophiolites. The southernmost area of the Ossa–Morena Zone, which bounds the Acebuches amphibolites, is composed of medium to high grade metamorphic rocks. The Ossa–Morena Zone-South Portuguese Zone suture preserves a complex story of middle to upper Devonian (?) to upper Stephanian sinistral transpression. The resulting structures were generated in a ductile to brittle regime. Transpressive shear zones affect the ophiolitic remnants and the high grade rocks of the southernmost area of the Ossa–Morena Zone. The late Hercynian faulting combines sinistral strike-slip movements and some thrusting component, which cut the suture to produce fish-like megaboudins. The transpressive regime can be explained by the oblique collision of the two plates now represented by the Ossa–Morena Zone and the South Portuguese Zone during the continental accretion. On the scale of the Hercynian Belt, this sinistral transpression belongs to a network of comparable structures explained by the impingement of the Ibero-Armorican Terranes.
Early to mid-Cretaceous tectonics and unconformities of the Wessex Basin (southern England)
Authors: RUFFELL A. H.
Published: July 2007

Sediment distribution patterns, time-subsidence plots, seismic data and outcrop analysis of the Lower Cretaceous (?Ryazanian-Albian) of the Wessex Basin, southern England, suggest that a number of unconformable horizons exist and that there is no single ‘late Cimmerian unconformity’ surface. A tectonic change, from areally restricted deposition in the Weald and Channel sub-basins to extensive sedimentation across the whole of southern England, began in the mid-Aptian. This change ended with transgression of basement ‘highs’ in the early Albian of the Dorset area, and later Albian of the Devon and London Platform basin margin areas: its onset can be linked to the Austrian tectonic phase of Europe. The onset of marine deposition in the Aptian is coincident with periodic transgression of the margins of the Wessex Basin throughout the Aptian-Albian. Mid-late Aptian and early/mid-AIbian transgressions were preceded by periods of erosion. The Aptian-Albian Lower Greensand is characterized by transgressive-regressive phases, suggesting a short-term controlling process (third-order eustatic changes or intra-plate mechanisms). Tectonic changes in the mid-Aptian include uplift followed by widespread subsidence. This change coincides with a time of plate reorganization in the European and North Atlantic areas.
Simulation of geological processes using an expert system
Authors: WADGE G. , YOUNG P. A. V. , MASON D. C.
Published: July 2007

Regional geological processes may be simulated rapidly using a combination of image processing and expert system techniques. Rapid, interactive simulations are achieved with image processing and a reduction of the problem to the two map dimensions. In order to manage these multiple simulations, expert system software is used to infer the optimum path through the modelling options. We illustrate our approach by referring to a computer system designed to produce maps of the prospectivity of carbonate-hosted Pb-Zn-F-Ba buried mineralization in the East Midlands of England. The system simulates the process of mineralization near the end of the Carboniferous involving the rapid expulsion of metal-rich brines from a series of small, shale basins by E-W compressive tectonism. There is preferential migration of these fluids along reactivated basin-bounding faults and deposition of the metals as sulphides within neighbouring limestone platforms. Computer simulation using this or similar approaches has particular potential for multidisciplinary projects in regional geology where disciplinary expertise in handling different types of data and in performing the simulation needs to be replicated.
How Mutational Networks Shape Evolution: Lessons from RNA Models
Authors: Cowperthwaite Matthew C. , Meyers Lauren Ancel
Published: July 2007

Recent advances in molecular biology and computation have enabled evolutionary biologists to develop models that explicitly capture molecular structure. By including complex and realistic maps from genotypes to phenotypes, such models are yielding important new insights into evolutionary processes. In particular, computer simulations of evolving RNA structure have inspired a new conceptual framework for thinking about patterns of mutational connectivity and general theories about the nature of evolutionary transitions, the evolutionary ascent of nonoptimal phenotypes, and the origins of mutational robustness and modular structures. Here, we describe this class of RNA models and review the major conceptual contributions they have made to evolutionary biology.
Mechanisms of Placebo and Placebo-Related Effects Across Diseases and Treatments
Authors: Benedetti Fabrizio
Published: July 2007

The placebo effect has evolved from being thought of as a nuisance in clinical and pharmacological research to a biological phenomenon worthy of scientific investigation in its own right. It is now clear that the term placebo effect is too restrictive and, in fact, many placebo-related effects have recently been investigated. A placebo effect differs from a placebo-like effect in that the former follows the administration of a placebo, whereas in the latter no placebo is administered. However, in both cases, the psychosocial context around the treatment plays a key role. In recent years, placebo and placebo-related effects have been analyzed with sophisticated biological tools that have uncovered specific mechanisms at both the biochemical and cellular level. This recent research has revealed that these psychosocial-induced biochemical changes in a patient's brain and body in turn may affect the course of a disease and the response to a therapy.
Reduced Risk of Atopic Sensitization among Farmers: The Humboldt Study
Authors: Chen Yue , Rennie Donna , Cormier Yvon , McDuffie Helen , Pahwa Punam , Dosman James
Published: July 2007

Background: It needs to be clarified whether farming is associated with a reduced risk of atopy or allergic condition. There is a lack of consistent evidence for prevalences of atopy, respiratory allergy and asthma in adult farmers. Methods: A cross-sectional study of adults (n = 2,081) was conducted in the town of Humboldt, Sask. Allergy skin prick tests were conducted to determine atopic sensitization. Respiratory allergy and physician-diagnosed asthma were based on self-reporting. Logistic regression was used to assess the associations of atopy, respiratory allergy and asthma with farming practices, adjusting for other important variables. Results: Of 2,081 participants, 27.8% were farmers. Reduced risks of atopic sensitization, respiratory allergy and asthma were observed among farmers compared to non-farmers. After adjustment for sex and age, which are major confounders, the odds ratio for atopic sensitization was 0.79 (95% confidence interval: 0.65, 0.97) for farmers versus non-farmers. Asthma showed a similar trend; however, there was no statistically significant difference in either respiratory allergy or asthma rates observed between farmers and non-farmers. Conclusions: The prevalence of atopy was lower in adult farmers than in non-farmers.
Cost Should Be the Principal Determinant of Choice of Erythropoiesis-Stimulating Agent in Chronic Haemodialysis Patients
Authors: Courtney Aisling E. , McNamee Peter T. , Maxwell A. Peter
Published: July 2007

Background/Aims: Erythropoiesis-stimulating agents (ESAs) are effective in the management of the anaemia of chronic kidney disease but add substantially to the treatment costs. We performed a comparison cross-sectional analysis of ESA prescribing in 4 dialysis centres in Northern Ireland. Methods: The ESA prescription and current haemoglobin (Hb) concentration for all patients on haemodialysis (HD) treatment for at least 3 months was extracted from the renal data system. Results: A total of 403 patients were analysed, 184 (46%) were prescribed epoetin β and 219 (54%) darbepoetin α. The mean Hb concentrations for both agents were comparable overall (Hb = 11.4 and 11.7 g/dl, p = 0.13), and for subcutaneous (SC) and intravenous (IV) administration: epoetin β 11.5 g/dl (n = 119) and 11.4 g/dl (n = 65) (p = 0.70), and darbepoetin α 11.8 g/dl (n = 39) and 11.6 g/dl (n = 180) (p = 0.49). The mean weekly dose was 7,941 units of epoetin β with SC and 9,200 units with IV administration (p = 0.10), and 45 µg SC and 46 µg IV of darbepoetin α (p = 0.94). The weekly cost of achieving equivalent Hb levels was GBP 61.86 (EUR 90.57/USD 115.68) with SC and GBP 71.67 (EUR 104.93/USD 134.02) with IV epoetin β, and GBP 70.78 (EUR 103.63/USD 132.36) with SC and GBP 72.18 (EUR 105.68/USD 134.98) with IV darbepoetin α. Conclusions: Epoetin β and darbepoetin α are equally effective ESAs and the choice of ESA prescribed in stable HD patients should be determined by cost.
Erythropoietin Therapy Decreased Tissue Factor, Its Pathway Inhibitor, and Oxidative Stress in Peritoneal Dialysis Patients with Diabetes
Authors: Pawlak Krystyna , Pawlak Dariusz , Mysliwiec Michal
Published: July 2007

Aims: We designed a study to evaluate whether erythropoietin (EPO), given to patients on continuousambulatory peritoneal dialysis (CAPD) both with and without diabetes mellitus (DM), influences tissue factor (TF), tissue factor pathway inhibitor (TFPI) and oxidative stress (SOX). Methods: We assessed TF, TFPI and a marker of SOX, Cu/Zn superoxide dismutase (Cu/Zn SOD) in 16 diabetic CAPD patients (8 with EPO therapy), 39 non-diabetic CAPD patients (23 with EPO therapy) and 18 healthy controls. Results: Patients on CAPD showed a significant increase in plasma concentrations of TF, TFPI and Cu/Zn SOD as compared to controls. EPO therapy was related to a decrease in these parameters in diabetic patients, whereas in non-diabetic patients EPO did not affect their levels. In diabetics, TF was positively correlated with TFPI and Cu/Zn SOD levels. There was a positive relationship between TFPI and Cu/Zn SOD, whereas inverse relationships existed between TFPI and haemoglobin, haematocrit (Ht), EPO dose and triglycerides. Multivariate analysis showed that independent variables linked to TFPI levels in diabetic patients were Cu/Zn SOD, Ht and EPO dose. Conclusion: Our data suggest that correction of anaemia with EPO therapy is associated with a significant decrease in TF, TFPI and SOX in diabetic CAPD patients.
Investigation of Vascular Endothelial Growth Factor Gene Polymorphisms and Its Association with Clinicopathologic Characteristics in Gastric Cancer
Authors: Chae Yee Soo , Kim Jong Gwang , Sohn Sang Kyun , Cho Yoon Young , Moon Joon Ho , Bae Han-Ik , Park Jae Yong , Lee Myung-Hoon , Lee Hyun-Chul , Chung Ho Young , Yu Wansik
Published: July 2007

Objective: Vascular endothelial growth factor (VEGF) is known to be a potent proangiogenic factor. This study evaluates the potential association of three VEGF gene polymorphisms (–460T > C, +405G > C, and 936C > T) with the susceptibility to and clinicopathologic characteristics of gastric cancer. Methods: The VEGF genotypes were determined using paraffin-embedded tissue from 413 patients who underwent a surgical resection and peripheral blood lymphocytes from 413 healthy controls by PCR-RFLP assay. Results: There was no difference in the allele frequency of –460T > C polymorphism. However, for the +405G > C polymorphism, the +405C allele was associated with a significantly decreased susceptibility to gastric cancer [odds ratio (OR) 0.686; 95% confidence interval (CI) 0.564–0.834]. Although there was no significant difference in the distribution of the 936C > T polymorphism between the two groups, the 936T allele was associated with a decreased susceptibility to gastric cancer (OR 0.757; 95% CI 0.591–0.970). In the haplotype analyses, the haplotype TCT (OR 0.405; 95% CI 0.263–0.624) was most closely associated with a decreased susceptibility to gastric cancer. However, no significant association was observed between the frequency of the genotypes or alleles and the clinicopathologic characteristics of gastric cancer. Conclusion: These observations imply that the VEGF gene polymorphisms may be associated with the susceptibility to gastric cancer. However, further studies of other VEGF sequence variants and their biological functions are needed to understand the role of the VEGF polymorphisms in determining the susceptibility to gastric cancer.
Regression of Electrocardiographic Left Ventricular Hypertrophy During Antihypertensive Therapy and Reduction in Sudden Cardiac Death
Authors: Wachtell Kristian , Okin Peter M. , Olsen Michael H. , Dahlöf Björn , Devereux Richard B. , Ibsen Hans , Kjeldsen Sverre E. , Lindholm Lars H. , Nieminen Markku S. , Thygesen Kristian
Published: July 2007

Background—

Sudden cardiac death (SCD) occurs more often in patients with ECG left ventricular (LV) hypertrophy. However, whether LV hypertrophy regression is associated with a reduced risk of SCD remains unclear.

Methods and Results—

The Losartan Intervention for End Point Reduction in Hypertension (LIFE) study included 9193 patients 55 to 80 years of age with essential hypertension and ECG LV hypertrophy by gender-adjusted Cornell product (CP) (RaVL+SV
3
[+6 mm in women]) · QRS duration>2440 mm · ms) and/or Sokolow-Lyon voltage (SLV) (SV
1
+RV
5/6
>38 mm). During follow-up (mean, 4.8 years), 190 patients (2%) experienced SCD. In time-dependent Cox analyses, absence of in-treatment LV hypertrophy was associated with a decreased risk of SCD: every 1-SD-lower in-treatment CP (1050 mm · ms) was associated with a 28% lower risk of SCD (hazard ratio [HR], 0.72; 95% CI, 0.66 to 0.79) and 1-SD-lower SLV (10.5 mm) with a 26% lower risk (HR, 0.74; 95% CI, 0.65 to 0.84). After adjustment for time-varying systolic and diastolic blood pressures, treatment allocation, age, gender, baseline Framingham risk score, ECG strain, heart rate, urine albumin/creatinine ratio, smoking, diabetes, congestive heart failure, coronary heart disease, atrial fibrillation, and occurrence of myocardial infarction, atrial fibrillation, heart failure, and noncardiovascular death, both in-treatment CP and SLV remained predictive of SCD: each 1-SD-lower CP was associated with a 19% lower risk of SCD (HR, 0.81; 95% CI, 0.73 to 0.90) and 1-SD-lower SLV with an 18% lower risk (HR, 0.82; 95% CI, 0.70 to 0.98). Absence of in-treatment LV hypertrophy by both SLV and CP was associated with a 30% lower risk of SCD (HR, 0.70; 95% CI, 0.54 to 0.92).

Conclusions—

Absence of in-treatment ECG LV hypertrophy is associated with reduced risk of SCD independently of treatment modality, blood pressure reduction, prevalent coronary heart disease, and other cardiovascular risk factors in hypertensive patients with LV hypertrophy.
Incidence and Predictors of Drug-Eluting Stent Thrombosis During and After Discontinuation of Thienopyridine Treatment
Authors: Airoldi Flavio , Colombo Antonio , Morici Nuccia , Latib Azeem , Cosgrave John , Buellesfeld Lutz , Bonizzoni Erminio , Carlino Mauro , Gerckens Ulrich , Godino Cosmo , Melzi Gloria , Michev Iassen , Montorfano Matteo , Sangiorgi Giuseppe Massimo , Qasim Asif , Chieffo Alaide , Briguori Carlo , Grube Eberhard
Published: July 2007

Background—

The need for prolonged aspirin and thienopyridine therapy and the risk of stent thrombosis (ST) remain as drawbacks associated with drug-eluting stents.

Methods and Results—

A prospective observational cohort study was conducted between June 2002 and January 2004 on 3021 patients consecutively and successfully treated in 5389 lesions with drug-eluting stents. Detailed patient information was collected on antiplatelet therapy. We analyzed the incidence of ST throughout the 18-month follow-up period and its relationship with thienopyridine therapy. ST occurred in 58 patients (1.9%) at 18 months. Forty-two patients (1.4%) experienced the event within 6 months of stent implantation. Acute myocardial infarction (fatal or nonfatal) occurred in 46 patients (79%) and death in 23 patients (39%) with ST. The median interval from discontinuation of thienopyridine therapy to ST was 13.5 days (interquartile range 5.2 to 25.7 days) for the first 6 months and 90 days (interquartile range 30 to 365 days) between 6 and 18 months. On multivariable analysis, the strongest predictor for ST within 6 months of stenting was discontinuation of thienopyridine therapy (hazard ratio, 13.74; 95% CI, 4.04 to 46.68;
P
<0.001). Thienopyridine discontinuation after 6 months did not predict the occurrence of ST (hazard ratio, 0.94; 95% CI, 0.30 to 2.98;
P
=0.92).

Conclusions—

Discontinuation of thienopyridine therapy was the major determinant of ST within the first 6 months, but insufficient information is available to determine whether there is benefit in continuing a thienopyridine beyond 6 months.
Mechanism of Gender-Specific Differences in Aortic Stiffness With Aging in Nonhuman Primates
Authors: Qiu Hongyu , Depre Christophe , Ghosh Kaushik , Resuello Ranillo G. , Natividad Filipinas F. , Rossi Franco , Peppas Athanasios , Shen You-Tang , Vatner Dorothy E. , Vatner Stephen F.
Published: July 2007

Background—

Our hypothesis was that the changes in vascular properties responsible for aortic stiffness with aging would be greater in old male monkeys than old female monkeys.

Methods and Results—

We analyzed the effects of gender differences in aging on in vivo measurements of aortic pressure and diameter and on extracellular matrix of the thoracic aorta in young adult (age, 6.6±0.5 years) versus old adult (age, 21.2±0.2 years) monkeys (
Macaca fascicularis
). Aortic stiffness, as represented by the pressure strain elastic modulus (Ep), increased more in old male monkeys (5.08±0.81;
P
<0.01) than in old females (3.06±0.52). In both genders, collagen density was maintained, collagen-bound glycation end products increased, and collagen type 1 decreased. However, elastin density decreased significantly (from 22±1.5% to 15±1.2%) with aging (
P
<0.05) only in males. Furthermore, only old males were characterized by a decrease (
P
<0.05) in collagen type 3 (an isoform that promotes elasticity) and an increase in collagen type 8 (an isoform that promotes the neointimal migration of vascular smooth muscle cells). In contrast to the data in monkeys, collagen types 1 and 3 both increased significantly in aging rats.

Conclusions—

There are major species differences in the effects of aging on aortic collagen types 1 and 3. Furthermore, because alterations in collagen density, collagen content, hydroxyproline, and collagen advanced glycation end products were similar in both old male and female monkeys, these factors cannot be responsible for the greater increase in stiffness in old males. However, changes in collagen isoforms and the decrease in elastin observed only in old males likely account for the greater increase in aortic stiffness.
Developmental Programming of Renal Glucocorticoid Sensitivity and the Renin-Angiotensin System
Authors: Wyrwoll Caitlin S. , Mark Peter J. , Waddell Brendan J.
Published: July 2007

Fetal glucocorticoid excess leads to subsequent adult hypertension, but the mechanisms involved in this developmental programming remain largely unknown. In this study we tested the hypothesis that programmed hypertension in rats is linked to altered renal expression of the glucocorticoid receptor, mineralocorticoid receptor, and 11β-hydroxysteroid dehydrogenase type 2 and components of the intrarenal and adipose renin-angiotensin system. The interactive effects of a postnatal diet enriched in omega-3 fatty acids, which prevents emergence of the hypertensive phenotype, were also examined. Maternal dexamethasone (0.75 μg/mL of drinking water from day 13 to term) markedly increased renal expression of the glucocorticoid receptor in 6-month-old offspring, and this was associated with hypomethylation of the glucocorticoid receptor promoter; renal MR was unaffected. In contrast, maternal dexamethasone reduced renal 11β-hydroxysteroid dehydrogenase type 2 in offspring, but this effect was prevented by a high omega-3 diet. Consistent with these effects, renal Na/K-ATPase-α1 was elevated in offspring of dexamethasone-treated mothers, but only in those raised on the standard diet. Maternal dexamethasone also programmed increased expression of renal and adipose angiotensin-converting enzyme and renal renin, but among these changes, only that of renal angiotensin-converting enzyme was prevented by the omega-3 diet. Our data support the hypothesis that programmed hypertension is mediated, in part, by increased renal glucocorticoid sensitivity, with consequent stimulatory effects on Na/K-ATPase-α1 and intrarenal renin-angiotensin system components. Partial prevention of programmed changes in renal gene expression by postnatal dietary omega-3 fatty acids provides insight into how this intervention prevents hypertension induced by fetal glucocorticoid excess.
Nebivolol Induces Nitric Oxide Release in the Heart Through Inducible Nitric Oxide Synthase Activation
Authors: Maffei Angelo , Di Pardo Alba , Carangi Rosa , Carullo Pierluigi , Poulet Roberta , Gentile Maria T. , Vecchione Carmine , Lembo Giuseppe
Published: July 2007

Nebivolol is a β1-adrenergic receptor antagonist that also reduces blood pressure by evoking endothelial NO production and vasodilation. We aimed at assessing whether nebivolol induces NO production also in the heart and delineating the molecular mechanisms involved. Using the fluorescent probe diaminofluorescein, we found that nebivolol induces a dose-dependent NO production in the heart, statistically significant already at 10
−7
mol/L. It is not an effect because of the blockade of β1-adrenergic receptor, because this effect is not shared by another drug of the same class, atenolol. Because nebivolol has been reported to act as an agonist on other β-adrenergic receptors, we tested NO production in the presence of receptor antagonists. Nebivolol was not able to induce NO production in presence of the β3-antagonist SR59230A, indicating a fundamental role for β3-adrenergic receptors in cardiac NO production by nebivolol. Moreover, inducible NO synthase inhibition abolishes NO release in the heart, indicating that nebivolol induces NO production by acting on the inducible isoform of the enzyme. The action of nebivolol on inducible NO synthase was confirmed by real-time PCR experiments, showing cardiac overexpression of inducible NO synthase but not neuronal NO synthase or endothelial NO synthase, after 5 hours of treatment with nebivolol. In conclusion, our study demonstrates that nebivolol also stimulates NO production in the heart. This action of nebivolol is exerted via a signaling pathway starting from the activation of β3-adrenergic receptors and leading to overexpression of inducible NO synthase. Cardiac NO production by nebivolol could participate in the cardiovascular effects of nebivolol treatment in patients affected by hypertension and heart failure.
Angiotensin II Chronic Infusion Induces B1 Receptor Expression in Aorta of Rats
Authors: Ceravolo Graziela S. , Fernandes Liliam , Munhoz Carolina D. , Fernandes Denise C. , Tostes Rita C.A. , Laurindo Francisco R.M. , Scavone Christoforo , Fortes Zuleica B. , Carvalho Maria Helena C.
Published: July 2007

We investigated whether angiotensin II infusion modulates in vivo the kinin B1 receptor expression and the mechanisms involved in this process. We also evaluated the role of the B1 receptor activation in aorta. Wistar rats received 400 ng/kg per minute of angiotensin II or saline (control rats) infusion during 14 days through an osmotic minipump. To investigate the role of superoxide anion in B1 receptor expression, rats received a reduced nicotinamide-adenine dinucleotide phosphate oxidase inhibitor in the drinking water during 14 days (60 mg/L of apocynin) simultaneously with angiotensin II infusion. Angiotensin II induced B1 receptor expression in the aorta and increased significantly systolic blood pressure, superoxide anion, and the nuclear factor κB activity. Apocynin treatment did not alter the blood pressure levels of angiotensin II rats and reduced the B1 receptor expression, superoxide anion generation, and nuclear factor κB activity to similar levels of the control rats. Vascular reactivity studies in isolated aorta reveal that B1 receptor agonist promoted endothelium-dependent dilation and increased the NO generation in aorta of angiotensin II rats. NO synthase inhibitor and B1 receptor antagonist inhibited the vasodilation and NO generation, which were not affected by B2 receptor antagonist or indomethacin. These results provide evidence that angiotensin II induces B1 receptor expression in aorta by superoxide anion generation, via reduced nicotinamide-adenine dinucleotide phosphate oxidase, concomitant to nuclear factor κB activation. We have also shown that B1 receptor agonist causes endothelium-dependent vasodilation through NO production in aortic rings, suggesting that the B1 receptor expression could be related with the vascular tonus control of angiotensin II rats.
Chronic Activation of Endothelin B Receptors
Authors: Fink Gregory , Li Melissa , Lau Yanny , Osborn John , Watts Stephanie
Published: July 2007

Endothelin (ET) exerts powerful pressor actions primarily through activation of the ET
A
receptor subtype. The ET
B
receptor (ET
B
R) subtype, on the other hand, is generally thought to initiate physiological actions that decrease arterial pressure. Such actions include clearing ET from the bloodstream, initiating endothelium-mediated vasodilation, and facilitating renal sodium and water excretion. The effect of long-term activation of the ET
B
R on arterial pressure, however, never has been directly tested. In this study we evaluated cardiovascular responses to chronic (5-day) activation of ET
B
R in male rats using continuous intravenous infusion of the selective agonist sarafotoxin 6c. Surprisingly, we found that sarafotoxin 6c caused a sustained increase in arterial pressure that rapidly reversed on termination of infusion. The hypertension was associated with increased renal excretion of sodium and water and decreased plasma volume. Alterations in daily sodium intake did not affect the magnitude of the hypertension. Hemodynamic studies revealed a decreased cardiac output and increased total peripheral resistance during sarafotoxin 6c infusion. Infusion of sarafotoxin 6c caused a small increase in plasma ET levels. Nevertheless, the hypertension was not affected by coadministration of a selective ET
A
receptor antagonist (atrasentan) but was completely prevented by treatment with a combined ET
A
receptor and ET
B
R antagonist (A186280). These experiments reveal for the first time that chronic activation of ET
B
R in rats causes sustained hypertension.