bluuebunny/crossref_metadata_2025 huggingface dataset:
Testing the interaction between inter-sexual competition and phosphorus availability in a dioecious grass
Authors: Rogers Sally R. , Eppley Sarah M.
Published: August 2012

Spatial segregation of the sexes (SSS) occurs in many dioecious plants, usually along an environmental gradient. However, little data is available on how male and female plants of species with SSS respond to environmental conditions along these gradients. We examined whether male and female plants of Distichlis spicata (L.) Greene, a dioecious grass species that exhibits extreme SSS along a phosphorus gradient, differed in their responses to phosphorus and competition treatments in the greenhouse. We found little evidence that phosphorus plays a role in SSS in D. spicata. However, supporting earlier work, we found that plants subject to inter-sexual competition were significantly more likely to have high root/shoot ratios than plants subject to intra-sexual competition, suggesting that competition is an important driver of SSS in this species.
The estimation and robustness of FMSY and alternative fishing mortality reference points associated with high long-term yield
Authors: Horbowy Jan , Luzeńczyk Anna
Published: August 2012

Equations for equilibrium yield and biomass are presented and used to derive FMSY and alternative reference points (ARPs). ARPs are analogues of the traditional points based on yield-per-recruit (YPR) or spawning stock-per-recruit (SPR) (F0.1, F40%, F50%), but refer to the equilibrium total yield or biomass. The method combines YPR and SPR analysis with stock–recruitment relationships. The sensitivity of FMSY and ARPs to the range of available stock–recruitment data, recruitment variance, various steepness levels in the stock–recruitment models, assessment variance, and bias are tested. The analysis showed that in most cases, F40%B and F50%B, defined by the equilibrium biomass (B), were the most robust relative to the different sources of uncertainty. However, in the case of the misspecification of the stock–recruitment relationship, FMSY showed superior performance. F40%B for the Beverton and Holt stock–recruitment model and F50%B for the Ricker recruitment model can be recommended as conservative fishing mortalities associated with high long-term yield. For the considered steepness, they produced yield up to 5%–10% lower than yield at FMSY.
Latitudinal and seasonal effects on growth of the Australian eastern king prawn (Melicertus plebejus)
Authors: Lloyd-Jones Luke R. , Wang You-Gan , Courtney Anthony J. , Prosser Andrew J. , Montgomery Steven S.
Published: August 2012

The growth of the Australian eastern king prawn ( Melicertus plebejus ) is understood in greater detail by quantifying the latitudinal effect. The latitudinal effect is the change in the species’ growth rate during migration. Mark–recapture data (N = 1635, latitude 22.21°S–34.00°S) presents northerly movement of the eastern king prawn, with New South Wales prawns showing substantial average movement of 140 km (standard deviation: 176 km) north. A generalized von Bertalanffy growth model framework is used to incorporate the latitudinal effect together with the canonical seasonal effect. Applying this method to eastern king prawn mark–recapture data guarantees consistent estimates for the latitudinal and seasonal effects. For M. plebejus, it was found that growth rate peaks on 25 and 29 January for males and females, respectively; is at a minimum on 27 and 31 July, respectively; and that the shape parameter, k (per year), changes by –0.0236 and –0.0556 every 1 degree of latitude south increase for males and females, respectively.
Small-scale dispersal and population structure in stream-living brown trout (Salmo trutta) inferred by mark–recapture, pedigree reconstruction, and population genetics
Authors: Vøllestad Leif Asbjørn , Serbezov Dimitar , Bass Arthur , Bernatchez Louis , Olsen Esben Moland , Taugbøl Annette
Published: August 2012

Many animals move among habitats, and even small-scale dispersal of individuals between habitat patches may have strong implications for population dynamics and structure. Here, we use long-term mark–recapture data combined with extensive genotyping and parentage assignment to investigate the importance of small-scale location change of resident brown trout ( Salmo trutta ) in a small stream (1500 m). During the first summer, juvenile fish dispersed downstream (mean displacement 200 m), with smaller juveniles dispersing longer distances. Downstream movement was also predominant during the first winter, but older fish moved little. This limited dispersal resulted in a significant isolation-by-distance structure for ages 1 and 2, but not for older age groups or for the mature fish. Individual pairwise relatedness coefficients decreased with waterway distance for mature fish during the 2002 and 2003 spawning seasons, but only weakly. Overall, between-site genetic differentiation was stronger for the younger age classes, and the signal decayed with age, indicating that the genetic structure observed in the stream is mainly driven by spatial aggregation of close relatives.
Allopatric distribution of generalist parasites: interplay between postglacial dispersal and host species
Authors: Cyr Frédéric , Peres-Neto Pedro , Angers Bernard
Published: August 2012

Dispersal of freshwater mussels occurs when the larvae parasitize fishes. In northeastern North America, distributions of floater mussels ( Pyganodon  spp.) are allopatric and arranged in an east–west pattern that corresponds poorly with the biogeographic patterns of the regional fish fauna. This study aims at determining whether associations with distinct fish species can explain the distribution of floaters. Here, we devised a framework based on a series of novel distributional null models to elucidate dispersal of species that are dependent on host species. The distributional patterns of floaters were tested by controlling for associations with fishes, while host–parasite associations were assessed with null models based on co-occurrence patterns. The disjoint distribution of the giant floater ( Pyganodon grandis ) and the eastern floater ( Pyganodon cataracta ) could not be explained by their association with distinct host fish and is likely the result of associations with distinct host populations rather than distinct species. In contrast, the distribution of the Newfoundland floater ( Pyganodon fragilis ) could be explained by its association with euryhaline fishes. Such associations may have also promoted differentiation with its sister taxa, the eastern floater. This study demonstrated the effects of positive biological associations on distributional patterns and the utility of a null model framework to uncover them.
Spawning biomass reference points for exploited marine fishes, incorporating taxonomic and body size information
Authors: Thorson James T. , Cope Jason M. , Branch Trevor A. , Jensen Olaf P.
Published: August 2012

Surplus production represents the processes that affect sustainable fishery harvest and is central to the ecology and management of marine fishes. Taxonomy and life history influence the ratio of spawning biomass at maximum sustainable yield to average unfished spawning biomass (SBMSY/SB0), and estimating this ratio for individual stocks is notoriously difficult. We use a database of published landings data and stock assessment biomass estimates and determine that process errors predominate in this data set by fitting a state–space model to data from each stock individually. We then fit multispecies process-error models while treating SBMSY/SB0as a random effect that varies by taxonomic order and maximum length. The estimated SBMSY/SB0 = 0.40 for all 147 stocks is intermediate between the values assumed by the Fox and the Schaefer models, although Clupeiformes and Perciformes have lower and Gadiformes and Scorpaeniformes have higher SBMSY/SB0values. Model selection supports the hypothesis that large-bodied fishes for a given taxonomic order have relatively higher SBMSY/SB0. Results can be used to define reference points for data-poor fisheries or as input in emerging assessment methods.
Targeting bigger schools can reduce ecosystem impacts of fisheries
Authors: Dagorn Laurent , Filmalter John D. , Forget Fabien , Amandè Monin Justin , Hall Martin A. , Williams Peter , Murua Hilario , Ariz Javier , Chavance Pierre , Bez Nicolas
Published: August 2012

Sustainability of living resource exploitation relies on an ecosystem management approach. Within tropical tuna purse seine fisheries using fish aggregating devices (FADs), such an approach incorporates the reduction of bycatch, in particular vulnerable species such as elasmobranchs. The levels of total bycatch (in mass) from fishing operations using FADs is known to be five times higher than when tuna are caught in free-swimming schools. We intend to find practical solutions to reduce bycatch in FAD sets through the investigation of the relationships between the ratio of bycatch to target catch across different set size classes in all oceans. Ratios were always highest when catches were small, with the smallest class of catches responsible for the highest total portion of bycatch (23%–43%) while only contributing negligibly to the total target catch (3%–10%). Reducing the number of fishing sets (a part of the total effort) while maintaining the same total yield could contribute to a substantial reduction in the impacts of human activities.
The endoplasmic reticulum in cardiovascular health and disease
Authors: Millott Robyn , Dudek Elzbieta , Michalak Marek
Published: August 2012

The endoplasmic reticulum has an intricate network of pathways built to deal with the secretory and integral membrane protein synthesis demands of the cell, as well as adaptive responses set up for the endoplasmic reticulum to rely on when stressed. These pathways are both essential and complex, and because of these 2 factors, several situations can lead to a dysfunctional endoplasmic reticulum and result in a dysfunctional cell with the potential to contribute to the progression of disease. The endoplasmic reticulum has been implicated in several metabolic, neurodegenerative, inflammatory, autoimmune, and renal diseases and disorders, and in particular, cardiovascular diseases. The role of the endoplasmic reticulum in cardiovascular disease shows how the change in function of a particular microscopic organelle can lead to macroscopic changes in the form of disease.
High cholesterol diet effects on ischemia–reperfusion injury of the heart
Authors: D’Annunzio Verónica , Donato Martín , Buchholz Bruno , Pérez Virginia , Miksztowicz Verónica , Berg Gabriela , Gelpi Ricardo J.
Published: August 2012

Ischemic heart disease is the leading cause of morbi-mortality in developed countries. Both ischemia–reperfusion injury and mechanisms of cardioprotection have been studied for more than 50 years. It is known that the physiopathological mechanism of myocardial ischemia involves several factors that are closely related to its development, of which hypercholesterolemia is one of the main ones. Therefore, the objective of this review was to elucidate the effects of a high-cholesterol diet on normal ventricular function and ischemia–reperfusion injury associated phenomenon such as post-ischemic ventricular dysfunction (stunned myocardium). Although there exist many studies considering several aspects of this physiopathological entity, the majority were carried out on normal animals. Thus, experiments carried out on hypercholesterolemic models are controversial, in particular those evaluating different mechanisms of cardioprotection such as ischemic preconditioning and postconditioning, and cardioprotection granted by drugs such as statins, which apart from exerting a lipid-lowering effect, exert pleiotropic effects providing cardioprotection against ischemia–reperfusion injury. These controversial results concerning the mechanisms of cardioprotection vary according to quality, composition, and time of administration of the high-cholesterol diet, as well as the species used in each experiment. Thus, to compare the results it is necessary to take all of these variables into account, since they can change the obtained results.
The ability of phosphodiesterase-5 inhibitors sildenafil and ordonafil to reverse L-NAME induced cardiac hypertrophy in the rabbit: possible role of calcineurin and p38
Authors: Zeidan Asad , Siam Aiad , Al Kaabba Abdulaziz , Mohammad Mukhallad , Khatib Said
Published: August 2012

Phosphodiesterase 5 inhibitors (PDE-5Is) can suppress and (or) reverse pressure overload induced myocardial hypertrophy. This study investigated the suppressive effect of 2 PDE-5Is (sildenafil and ordonafil) on N-nitro-l-arginine methyl ester (L-NAME)-induced cardiac hypertrophy in rabbit heart, and examined their possible mechanism of action. L-NAME increased left ventricular thickness to 6.1± 0.18 mm from 4.6 ± 0.13 mm (p < 0.05), which regressed after treatment with either sildenafil or ordonafil to 5.1 ± 0.1 mm and 4.8 ± 0.2 mm, respectively (p < 0.05). Phenylephrine increased neonatal rat ventricular myocyte cell surface area to 131% ± 3% of the control value, which was associated with significant increment in ERK1/2 to 143% ± 5% of the control value (p < 0.05). Ordonafil and sildenafil decreased cell surface area to 95% ± 3% and 90% ± 1% of the control value, respectively. Both drugs decreased ERK1/2 to 88% ± 4% of the control value. Calcineurin activity was significantly decreased after 1 h of treatment with 0.1 mg·L–1 ordonafil (1.15 ± 0.05, p < 0.05). For sildenafil (0.1 mg·L–1), calcineurin activity significantly decreased only after 24 h of incubation (22%). Also p38 activation was attenuated by ordonafil and sildenafil (0.1 mg·L–1). It is suggested that both drugs have the ability to reverse L-NAME-induced cardiac hypertrophy and suppress phenylphrine-induced myocyte hypertrophy, and that these effects may be mediated through the attenuation of calcineurin and its downstream signaling pathways (p38) in neonatal rat ventricular myocytes.
Up-regulation of myocardial connexin-43 in spontaneously hypertensive rats fed red palm oil is most likely implicated in its anti-arrhythmic effects
Authors: Bačová Barbara , Radošinská Jana , Viczenczová Csilla , Knezl Vladimír , Dosenko Victor , Beňova Tamara , Navarová Jana , Gonçalvesová Eva , van Rooyen Jacques , Weismann Peter , Slezák Jan , Tribulová Narcis
Published: August 2012

The purpose of this study was to test our hypothesis that red palm oil (RPO) intake may affect abnormalities of myocardial connexin-43 (Cx43) and protein kinase Cε (PKCε) signaling, and consequently the propensity of the spontaneously hypertensive rat heart (SHR) heart to arrhythmias. SHR and Wistar–Kyoto (WKY) rats fed a standard rat chow plus red palm oil (200 µL/day) for 5 weeks were compared with untreated rats. Cytosolic but not particulate PKCε expression as well as Cx43-mRNA, total Cx43 proteins, and its phoshorylated forms were increased, and disordered localization of Cx43 was attenuated in the left ventricle of RPO-fed SHR compared with untreated rats. These alterations were associated with suppression of early post-ischemic-reperfusion-related ventricular tachycardia and electrically inducible ventricular fibrillation. However, the treatment dose of RPO caused down-regulation of myocardial Cx43, but did not alter its cell membrane distribution or overall PKCε expression in WKY rats. It was, however, associated with poor arrhythmia protection, suggesting overdosing. Results indicate that SHR benefit from RPO intake, particularly because of its apparent anti-arrhythmic effects. This protection can be, in part, attributed to the preservation of cell-to-cell communication via up-regulation of myocardial Cx43, but not with PKCε activation.
The acutely occluded left main coronary artery culprit in cardiogenic shock and initial percutaneous coronary intervention: a substudy of the Manitoba “no option” left main PCI registry
Authors: Hussain Farrukh , Nguyen Thang , Elmayergi Nader , Ducas John , Minhas Kunal , Vo Minh , Kass Malek , Ravandi Amir , Parmar Gurpreet , Jassal Davinder S. , Tam James W. , Freed Darren , Menkis Alan H. , Philipp Roger K.
Published: August 2012

We aim to describe the in-hospital outcomes of the first reported Canadian cohort of patients with cardiogenic shock and acute myocardial infarction (MI) due to acute and total occlusion of the left main coronary artery, treated with initial percutaneous coronary intervention (PCI). Acute left main thromboses with cardiogenic shock were identified (N = 8) from a retrospective consecutive cohort of high risk left main PCI (N = 56) performed at our institution from 2004–2009. The mean age was 62.3 ± 13.2 years, with 6 (75%) male patients. Successful PCI was performed in all patients, with thrombectomy utilized in 4 patients (50%), stenting in 7 patients (88%), and intra-aortic balloon pump augmentation in 7 patients (88%). Two patients (25%) required extracorporeal membrane oxygenation (ECMO) and 2 other patients required ventricular assist devices. Post-PCI coronary artery bypass grafting (CABG) was performed for 2 patients (25%). The mean SYNTAX score was 26.6 ± 10.5. The mean logistic EuroSCORE was 30.4 ± 12.6%. In-hospital mortality occurred in 3 patients (38%). Acute left main occlusion is a rare but devastating presentation of myocardial infarction, invariably with cardiogenic shock. Emergent PCI may be an effective method to acutely revascularize this subset of patients; however, aggressive post-PCI care including ECMO, CABG, and ventricular support may be required to improve patient survival.
Expression profiles of metamorphosis-related genes during natural transformations in tadpoles of wild Wood Frogs (Lithobates sylvaticus)
Authors: Navarro-Martín Laia , Lanctôt Chantal , Edge Christopher , Houlahan Jeff , Trudeau Vance L.
Published: August 2012

Numerous studies using laboratory-reared tadpoles have shown the importance of thyroid hormones (TH), thyroid receptors (TR), and deiodinase (Dio) enzymes during anuran metamorphosis. Our study focuses on the analysis of thyroid-related genes in tadpoles of wild Wood Frogs ( Lithobates sylvaticus (LeConte, 1825); also known as Rana sylvatica (Cope, 1889)) during metamorphosis. Results showed that, in concordance with laboratory-reared studies, thyroid receptor beta (trb) gene expression profiles presented the most marked changes. At climax and compared with premetamorphic stages, brains, tails, and gonad–mesonephros complex (GMC) tissues increased trb expression levels 5-, 21-, and 41-fold, respectively (p < 0.05). In addition, gene expression levels of brain deiodinase type II and III showed opposite trends, where 3-fold decrease and 10-fold increase were, respectively, found. This finding supports the idea that thyroid hormone, as it has been demonstrated in laboratory-reared tadpoles, is also involved in natural metamorphosis in wild tadpoles. Interestingly, and contrary to our predictions, we observed that whole brain corticotropin-releasing factor (crf) and crf receptor 1 (crfr1) gene expression levels significantly decrease through metamorphosis in wild L. sylvaticus tadpoles. Further analyses are required to determine if a role of TH in the timing of anuran gonadal development exists, as well as the importance of cell-specific and tissue-specific expression of crf and crfr1 to metamorphosis.
From monogamy to complexity: social organization of arctic foxes (Vulpes lagopus) in contrasting ecosystems
Authors: Norén K. , Hersteinsson P. , Samelius G. , Eide N.E. , Fuglei E. , Elmhagen B. , Dalén L. , Meijer T. , Angerbjörn A.
Published: August 2012

Canids display pronounced intraspecific variation in social organization, ranging from single breeding females to large and complex groups. Despite several hypotheses in this matter, little is understood about the ecological factors underlying this flexibility. We have used the arctic fox ( Vulpes lagopus (L., 1758)) to investigate how contrasting ecosystem conditions concerning resources and predation influence group formation. We predicted that complex groups are more common in resource-rich ecosystems with predators, whereas simple groups occur in more marginal ecosystems without predators. Samples from 54 groups were collected from four populations of arctic foxes with contrasting prey resources and predation and these samples were genotyped in 10 microsatellite loci. We found considerable variation between ecosystems and a significant relationship between resources and formation of complex groups. We conclude that sufficient amounts of food is a prerequisite for forming complex groups, but that defense against predation further increases the benefits of living in larger groups. We present a conceptual model suggesting that a trade-off between the cost of resource depletion and the benefits obtained for guarding against predators explain the differences in social organization. The variable ecology of the arctic foxes makes it is a plausible model species for understanding the connection between ecology and social organization also in other species.
The cost of trying: weak interspecific correlations among life-history components in male ungulates
Authors: Festa-Bianchet Marco
Published: August 2012

Life-history trade-offs are well known in female mammals, but have seldom been quantified for males in polygynous species. I compared age-specific mass, weapon size, survival, and reproductive success of males in eight species of ungulates, and found weak interspecific correlations among life-history traits. Young males tended to have higher reproductive success in rapidly-growing than in slow-growing species, and in species where horns or antlers reached near-asymptotic size over the first few years of life. There was no clear interspecific trade-off between early reproduction and early survival. Reproductive senescence was evident in most species. Generation length, calculated as the mean age of fathers, was negatively correlated with the reproductive success of young males and positively with life expectancy of 3-year-olds, but not with early mortality. The main determinant of male reproductive success in polygynous ungulates is the ability to prevail against competing males. Consequently, the number and age structure of competitors should strongly affect an individual’s ability to reproduce, making classic trade-offs among life-history traits very context-dependent. Most fitness costs of reproduction in male ungulates likely arise from energy expenditure and injuries sustained while attempting to mate. Individual costs may be weakly correlated with fitness returns.
Estimating the influence of the thermal environment on activity patterns of the desert woodrat (Neotoma lepida) using temperature chronologies
Authors: Murray Ian W. , Smith Felisa A.
Published: August 2012

Environmental temperature influences the ecology and life history of animals. In habitats near the thermal range boundary, fluctuations in temperature may influence the ability of species to persist. Desert woodrats ( Neotoma lepida Thomas, 1893) occupy one of the hottest and most extreme environments in the western hemisphere, Death Valley, California, despite limited adaptations for water conservation or efficient heat dissipation. Moreover, N. lepida have a relatively low tolerance for high temperature. Thus, we hypothesized temperature might influence both the timing and the duration of activity. To test this idea, we attached iButton sensors to 56 animals over a 2-year period and recorded activity. Each sensor was set to record at 5 or 15 min intervals and stored approximately 2000 records before retrieval. We found a strong relationship between ambient temperature and onset and duration of activity, influenced by both body size and gender. Neotoma lepida did not emerge until air temperature fell below 42 °C. As daily high temperatures increased, both sexes had fewer nightly activity bouts of shorter duration. Our results suggest that activity of N. lepida is constrained during the climatically intense summer months. Animals face a trade-off between remaining in the thermal safety of the den vs. emerging to obtain resources.
Genetic structure of the arboreal squirrels (Glaucomys sabrinusandTamiasciurus hudsonicus) in the North American Black Hills
Authors: Kiesow A.M. , Monroe E.M. , Britten H.B.
Published: August 2012

We selected two isolated mammalian populations, the Black Hills northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) and red squirrel ( Tamiasciurus hudsonicus (Erxleben, 1777)), to elucidate their genetic structure. We trapped both squirrels from 2005 to 2007, in three regions of the Black Hills, differing in geology and vegetation, to collect ear samples for genetic analyses. Microsatellite loci (northern flying (9) and red squirrel (13)) were used to examine genetic structure. Data analyses estimated genetic variability, substructure, and gene flow. Northern flying and red squirrel populations have allelic diversity and observed heterozygosity similar to other isolated populations. Each species shows weak substructure from STRUCTURE and GENELAND analyses, suggesting squirrel movements may be inhibited by topography or unsuitable habitat. Recent gene flow estimates from BAYESASS indicate that both species experience some within population gene flow and red squirrels may be more structured than northern flying squirrels because of lower migration rates. Concordant patterns of genetic structure in northern flying and red squirrels indicate that other species’ movements in the Black Hills may be affected by topography and habitat. Because their habitat is isolated in the Black Hills, management practices and conservation measures are recommended to promote viability and survival of each species.
ON THE SEGMENTATION AND CLASSIFICATION OF HAND RADIOGRAPHS
Authors: DAVIS LUKE M. , THEOBALD BARRY-JOHN , LINES JASON , TOMS ANDONI , BAGNALL ANTHONY
Published: August 2012

This research is part of a wider project to build predictive models of bone age using hand radiograph images. We examine ways of finding the outline of a hand from an X-ray as the first stage in segmenting the image into constituent bones. We assess a variety of algorithms including contouring, which has not previously been used in this context. We introduce a novel ensemble algorithm for combining outlines using two voting schemes, a likelihood ratio test and dynamic time warping (DTW). Our goal is to minimize the human intervention required, hence we investigate alternative ways of training a classifier to determine whether an outline is in fact correct or not. We evaluate outlining and classification on a set of 1370 images. We conclude that ensembling with DTW improves performance of all outlining algorithms, that the contouring algorithm used with the DTW ensemble performs the best of those assessed, and that the most effective classifier of hand outlines assessed is a random forest applied to outlines transformed into principal components.
CONDENSATION OF THE SCALAR FIELD WITH STUCKELBERG AND WEYL CORRECTIONS IN THE BACKGROUND OF A PLANAR AdS–SCHWARZSCHILD BLACK HOLE
Authors: MOMENI D. , SETARE M. R. , MYRZAKULOV RATBAY
Published: August 2012

We study analytical properties of the Stuckelberg holographic superconductors with Weyl corrections. We obtain the minimum critical temperature as a function of the mass of the scalar field m2. We show that in limit of the [Formula: see text] which is close to the numerical estimate [Formula: see text]. Further we show that the mass of the scalar field is bounded from below by the [Formula: see text] where [Formula: see text]. This lower bound is weaker and different from the previous lower bound m2 = -3 predicted by stability analysis. We show that in the Breitenlohner–Freedman bound, the critical temperature remains finite. Explicitly, we prove that here there exists a linear relation between 〈OΔ〉 and the chemical potential.
A COMPLEX FINSLER APPROACH OF GRAVITY
Authors: MUNTEANU GHEORGHE , ALDEA NICOLETA
Published: August 2012

In this paper our aim is mainly to obtain a two-dimensional complex Finsler model of the real gravitation space-time. We prove that, at least in the special case of the weakly gravitational field, this is possible and it leads to some interesting geometrical and physical aspects, such as the study of curvature invariants with respect to complex Berwald frame, intensively studied recently by us for a two-dimensional complex Finsler space. A generalization of the Klein–Gordon equation is proposed and we find solutions which are in concordance to the classical plane wave solution of momentum-energy relation. The last part of the paper is devoted to some applications in which the complex gravitational potential leads to the Bergman metric and to a more general case which leads to a non-purely Hermitian complex Finsler metric, with negative curvature invariant.
Cancer cells uptake porphyrinsviaheme carrier protein 1
Authors: Hiyama Kazuhiro , Matsui Hirofumi , Tamura Masato , Shimokawa Osamu , Hiyama Mariko , Kaneko Tsuyoshi , Nagano Yumiko , Hyodo Ichinosuke , Tanaka Junko , Miwa Yoshihiro , Ogawa Tetsuo , Nakanishi Takeo , Tamai Ikumi
Published: August 2012

Although exogenous porphyrin accumulation in cancer cells is important for the success of photodynamic therapies, the mechanism is not clear. We hypothesized that a newly reported transporter, heme carrier protein 1 (HCP1), is highly expressed in cancer cells, and transports porphyrins into the cells. We investigated the following three unknowns: whether cancer cells take up hematoporphyrin derivative via HCP1, whether HCP1 is involved in photodynamic therapies, and whether cancer cells highly express HCP1. First, when HCP1-overexpressed cells were treated with hematoporphyrin derivative and then exposed to an eximer laser beam, they emitted a significantly higher intensity of hematoporphyrin derivative fluorescence and became more susceptible to the laser beam than control. Second, when three other types of cancer cells with silenced HCP1 were treated with hematoporphyrin derivative and then exposed to the laser beam, they emitted a significantly lower intensity of hematoporphyrin derivative fluorescence. Third, non-cancer cells slightly expressed HCP1; on the other hand, the three other types of cancer cells clearly expressed HCP1. These results indicated that cancer cells uptake hematoporphyrin derivative via HCP1 and over-expression of HCP1 increases the efficacy of photodynamic therapies by increasing porphyrin accumulation in the cells. This is the first report about a transporter of porphyrin in cancer cells.
HIGH DIELECTRIC CONSTANT COMPOSITE BASED ON CHLOROPHYLL A ENTRAPPED NANOPOROUS SILICA GEL
Authors: MANNA J. S. , MITRA M. K. , MUKHERJEE S. , DAS G. C.
Published: August 2012

Chlorophyll a (naturally occurring Mg porphyrene) has been entrapped in nano/porous silica gel using sol–gel method at room temperature, producing a stable composite. HRTEM observation reveals regular nanoscale [around 15–20 nm diameter] distribution of aggregated polycrystalline chlorophyll a within porous silica matrix. UV-vis study also corroborates the presence of various aggregated chlorophyll a species within the system. Low field measurement shows almost 400 times enhancement of dielectric constant (1700) with incorporation of only 0.125 mg/ml of chlorophyll and the loss is 0.5 at room temperature at 100 Hz. The dielectric constant of the composite reaches 2500 as chlorophyll concentration becomes 1 mg/ml. Observed strong space charge response to the external field and strong frequency dispersion of the dielectric properties of the composite can be attributed to the long-range electron delocalization [nomadic polarization] in chlorophyll a aggregates. The electric modulus (M*) formalism used in this study enabled us to distinguish and separate various relaxation processes. It is found that with increasing chlorophyll concentration D.C. relaxation time decreases exponentially at room temperature. It is shown that observed relaxations do not perfectly follow the Debye response in high frequency region due to heterogeneous distribution of chlorophyll aggregates. The low values of room temperature activation energy calculated from Arrhenius plot reveal that polaronic hopping phenomena is absent at grain-interfacial region due to low thermal energy.
CONDUCTIVITY AND DIELECTRIC BEHAVIOR OF PLiAMPS-BASED SEMI-IPN SINGLE ION CONDUCTOR PLASTICIZED WITH POLY(SILOXANE-G-ETHYLENE OXIDE)
Authors: CUI WEIWEI , TANG DONGYAN
Published: August 2012

Comb poly(siloxane-g-ethylene oxide) (PSi-PE) with high chain segmental mobility, as a plasticizer, was introduced into poly(lithium 2-acrylamido-2-methyl-1-propanesulfonate) (PLiAMPS)-based semi-interpenetrating polymer network single-ion conductors. The structures of PSi-PE and PLiAMPS were characterized by FTIR spectroscopy. The distribution of PSi-PE in polyelectrolyte matrix was investigated through observing the residual surface morphology of conductor membrane after being etched by toluene. AC impedance and dielectric behavior measurements were used to investigate the impact of PSi-PE on the ionic conductivity and to analyze the mechanism of conductivity variation. Compared with the unplasticized membranes, the ionic conductivity of the membrane with the addition of 35 wt.% PSi-PE was improved by 20 times. Meanwhile, the dielectric constant (ε) of the membrane was increased to 1330 and the relaxation time was decreased to 0.012 s. The changes of dielectric properties reflect directly the effect of PSi-PE on the dissociation ability of Li+and the chain segmental mobility, which well explains the reasons of ionic conductivity variation.
DIELECTRIC RESPONSE AND IMPEDANCE SPECTROSCOPY OF (Na0.5Bi0.5)0.95Ba0.05Zr0.04Ti0.96O3 FERROELECTRIC CERAMIC
Authors: TILAK B.
Published: August 2012

A new lead-free ferroelectric relaxor ceramic was prepared by conventional solid-state synthesis by modifying A-site and B-site in (Na0.5Bi0.5)TiO3 system, i.e., (Na0.5Bi0.5)0.95Ba0.05Zr0.04Ti0.96O3 (0.05BNBZT). X-ray diffraction studies reveal a single phase rhombohedral structure. Crystallite size and strain analysis has been done by Debye–Scherrer and Williamson–Hall technique. The tolerance factor is 0.81, indicating a stable Perovskite structure of the material. Scanning electron micrograph of the material shows a distribution of grains, average grain size is 1.41 μm. Dielectric response of (Na0.5Bi0.5)0.95Ba0.05 Zr0.04Ti0.96O3 , ferroelectric ceramic has been studied as a function of frequency over a wide range of temperatures. The studied ceramic exhibited maximum frequency dispersion in both real and imaginary part of dielectric susceptibility at and around the dielectric transition temperature (Tm). The frequency dependence of transition temperature, Tm (temperature of the maximum of dielectric constant) was studied in terms of Vogel–Fulcher relation. The dielectric relaxation of (Na0.5Bi0.5)0.95Ba0.05Zr0.04Ti0.96O3 ceramic was studied at different temperatures using the complex impedance (Z*) and electrical modulus (M*) formalism. Impedance measurements were made on over a wide range of temperatures (300–600°C) and frequencies (45 Hz–5 MHz) which show the presence of both grain and grain boundary effects in the material. The Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grain boundaries (at higher temperature), in addition to granular contribution (at all temperatures), which influences the device properties of a material. The electric modulus (M*) formalism used in the analysis enabled us to distinguish and separate the relaxation processes. Conductivity studies in the material obey the Jonscher's power law in frequency (45 Hz–5 MHz) and temperature (30–600°C). These results give evidence that the lead-free ferroelectric ceramics is extensively may be used for device and electronic applications, when compared with lead-based materials.
Formation of Step-Free Surfaces on Diamond (111) Mesas by Homoepitaxial Lateral Growth
Authors: Tokuda Norio , Makino Toshiharu , Inokuma Takao , Yamasaki Satoshi
Published: August 2012

We present a technique for the array formation of atomically step-free diamond surfaces on diamond (111) substrates by microwave plasma-enhanced chemical vapor deposition. With an appropriate choice of plasma conditions, the atomic steps initially present on each mesa surface move by lateral growth, and then, atomically step-free surfaces are successfully formed on diamond (111) mesas by microwave plasma-enhanced chemical vapor deposition. The lateral growth of diamond (111) films results in the formation of step-free surfaces with device dimensions up to 100 µm square on diamond (111) mesas. A limiting factor in scaling up the size and yield of the step-free mesas is the density of screw dislocations in the diamond substrate.
Magnetoelectric Coupling in Tb0.3Dy0.7Fe1.92/PbZr0.3Ti0.7O3Bilayer Thin Films
Authors: Yoon Dong Jin , Ryu Jungho , Koo Chang Young , Lee Jae-Yeoul , Lee Hee Young
Published: August 2012

The magnetoelectric (ME) properties of Tb0.3Dy0.7Fe1.92(Terfenol-D)/PbZr0.3Ti0.7O3(PZT) thin films grown on a Pt(111)/Ti/SiO2/Si(100) substrate were investigated. The ferroelectric behavior of a Terfenol-D/PZT bilayer film stack was examined by polarization–electric field hysteresis measurement. The remnant polarization (Pr) and coercive field (Ec) values were found as 31 µC/cm2and 124 kV/cm, respectively. The magnetic behavior was observed using a vibration sample magnetometer (VSM) at 300 K with saturation magnetization (Ms) and coercivity (Hc) values of 6.7 emu/cm3and 70 Oe, respectively. The application of magnetic field caused a piezomagnetic strain in the Terfenol-D layer hence, the piezoelectric voltage or charge in the PZT thin film was induced. The maximum magnetoelectric voltage coefficient (dE/dH) value of approximately 40 mV cm-1Oe-1was obtained at the magnetic field of 5 kOe.
Effect of Channel Dopant Non-uniformity on Transconductance Variability
Authors: Terada Kazuo , Takeda Ryo , Tsuji Katsuhiro , Tsunomura Takaaki , Nishida Akio , Mogami Tohru
Published: August 2012

The effect of the channel dopant non-uniformity on metal–oxide–semiconductor field-effect transistor (MOSFET) transconductance variability is studied using the simple current model and the test MOSFETs having various channel width and length. It is found that this effect is significant for relatively large MOSFETs.
Effect of Cell Position on Impedance Measurement in Microfluidic Channel with Planar Microelectrodes and a Three-Pillar Structure
Authors: Lai Sheng-Yu , Tsai Sung-Lin , Wang Min-Haw , Chen Ming-Kun , Jang Ling-Sheng
Published: August 2012

Impedance analysis of single cells offers the possibility of obtaining accurate, reliable, and in-depth information about their pathological condition. In this work, we present the physical capture of a single cell using a microfluidic device with a three-pillar microstructure, impedance measurement using a set of planar microelectrodes, and the derivation of an electrical model that fits the experimental results. The relationship between impedance characteristics and the location of a single HeLa cell (human cervical epithelioid carcinoma) is investigated by impedance spectroscopy. When a single cell fell toward the electrodes after it has been trapped by the three-pillar microstructure, the impedance and the phase change are measured in an operating frequency range of 1 to 100 kHz. The equivalent circuit model is established and two elements that depend on cell location are used to investigate the impedance change of a single HeLa cell.
Effects ofHange-shashin-to(TJ-14) andKeishi-ka-shakuyaku-to(TJ-60) on contractile activity of circular smooth muscle of the rat distal colon
Authors: Kito Yoshihiko , Teramoto Noriyoshi
Published: August 2012

The Japanese Kampo medicines Hange-shashin-to (TJ-14) and Keishi-ka-shakuyaku-to (TJ-60) have been used to treat symptoms of human diarrhea on an empirical basis as Japanese traditional medicines. However, it remains unclear how these drugs affect smooth muscle tissues in the distal colon. The aim of the present study was to investigate the effects of TJ-14 and TJ-60 on the contractile activity of circular smooth muscle from the rat distal colon. TJ-14 and TJ-60 (both 1 mg/ml) inhibited spontaneous contractions of circumferentially cut preparations with the mucosa intact. Blockade of nitric oxide (NO) synthase or soluble guanylate cyclase activity abolished the inhibitory effects of TJ-60 but only attenuated the inhibitory effects of TJ-14. Apamin (1 μM), a blocker of small-conductance Ca2+-activated K+channels (SK channels), attenuated the inhibitory effects of 5 mg/ml TJ-60 but not those of 5 mg/ml TJ-14. TJ-14 suppressed contractile responses (phasic contractions and off-contractions) evoked by transmural nerve stimulation and increased basal tone, whereas TJ-60 had little effect on these parameters. These results suggest that 1 mg/ml TJ-14 or TJ-60 likely inhibits spontaneous contractions of the rat distal colon through the production of NO. Activation of SK channels seems to be involved in the inhibitory effects of 5 mg/ml TJ-60. Since TJ-14 has potent inhibitory effects on myogenic and neurogenic contractile activity, TJ-14 may be useful in suppressing gastrointestinal motility.
Mechanism and regulation of vitamin B2 (riboflavin) uptake by mouse and human pancreatic β-cells/islets: physiological and molecular aspects
Authors: Ghosal Abhisek , Said Hamid M.
Published: August 2012

Riboflavin (RF) is essential for the normal metabolic activities of pancreatic β-cells and provides protection against oxidative stress. Very little is known about the mechanism of RF uptake by these cells and how the process is regulated. We addressed these issues using mouse-derived pancreatic β-TC-6 cells and freshly isolated primary mouse and human pancreatic islets. Our results showed3H-RF uptake by β-TC-6 cells is Na+independent, cis inhibited by RF-related compounds, trans stimulated by unlabeled RF, and saturable as a function of concentration (apparent Kmof 0.17 ± 0.02 μM). The latter findings suggest involvement of a carrier-mediated process. Similarly, RF uptake by primary mouse and human pancreatic islets was via carrier-mediated process. RF transporters 1, 2, and 3 (RFVT-1, -3, and -2) were all expressed in mouse and human pancreatic β-cells/islets, with RFVT-1 being the predominant transporter expressed in the mouse and RFVT-3 in the human. Specific knockdown of RFVT-1 with gene-specific small interfering RNA leads to a significant inhibition in RF uptake by β-TC-6 cells. RF uptake by β-TC-6 cells was also found to be adaptively upregulated in RF deficiency via a transcriptional mechanism(s). Also, the process appears to be under the regulation of a Ca2+/calmodulin-mediated regulatory pathway. Results of these studies demonstrate, for the first time, the involvement of a carrier-mediated process for RF uptake by mouse and human pancreatic β-cells/islets. Furthermore, the process appears to be regulated by extracellular and intracellular factors.
Uremic cardiomyopathy is characterized by loss of the cardioprotective effects of insulin
Authors: Semple David J. , Bhandari Sunil , Seymour Anne-Marie L.
Published: August 2012

Chronic kidney disease is associated with a unique cardiomyopathy, characterized by a combination of structural and cellular remodeling, and an enhanced susceptibility to ischemia-reperfusion injury. This may represent dysfunction of the reperfusion injury salvage kinase pathway due to insulin resistance. The susceptibility of the uremic heart to ischemia-reperfusion injury and the cardioprotective effects of insulin and rosiglitazone were investigated. Uremia was induced in Sprague-Dawley rats by subtotal nephrectomy. Functional recovery from ischemia was investigated in vitro in control and uremic hearts ± insulin ± rosiglitazone. The response of myocardial oxidative metabolism to insulin was determined by13C-NMR spectroscopy. Activation of reperfusion injury salvage kinase pathway intermediates (Akt and GSK3β) were assessed by SDS-PAGE and immunoprecipitation. Insulin improved postischemic rate pressure product in control but not uremic hearts, [recovered rate pressure product (%), control 59.6 ± 10.7 vs. 88.9 ± 8.5, P < 0.05; uremic 19.3 ± 4.6 vs. 28.5 ± 10.4, P = ns]. Rosiglitazone resensitized uremic hearts to insulin-mediated cardioprotection [recovered rate pressure product (%) 12.7 ± 7.0 vs. 61.8 ± 15.9, P < 0.05]. Myocardial carbohydrate metabolism remained responsive to insulin in uremic hearts. Uremia was associated with increased phosphorylation of Akt (1.00 ± 0.08 vs. 1.31 ± 0.11, P < 0.05) in normoxia, but no change in postischemic phosphorylation of Akt or GSK3β. Akt2 isoform expression was decreased postischemia in uremic hearts ( P < 0.05). Uremia is associated with enhanced susceptibility to ischemia-reperfusion injury and a loss of insulin-mediated cardioprotection, which can be restored by administration of rosiglitazone. Altered Akt2 expression in uremic hearts post-ischemia-reperfusion and impaired activation of the reperfusion injury salvage kinase pathway may underlie these findings.
Melanocortin antagonism ameliorates muscle wasting and inflammation in chronic kidney disease
Authors: Cheung Wai W. , Mak Robert H.
Published: August 2012

Aberrant melanocortin signaling has been implicated in the pathogenesis of wasting in chronic kidney disease (CKD). Previously, we demonstrated that agouti-related peptide (AgRP), a melenocortin-4 receptor antagonist, reduced CKD-associated cachexia in CKD mice. Our previous studies with AgRP utilized dual energy X-ray (DXA) densitometry to assess the body composition in mice (Cheung W, Kuo HJ, Markison S, Chen C, Foster AC, Marks DL, Mak RH. J Am Soc Nephrol 18: 2517–2524, 2007; Cheung W, Yu PX, Little BM, Cone RD, Marks DL, Mak RH. J Clin Invest 115: 1659–1665, 2005). DXA is unable to differentiate water content in mice, and fluid retention in CKD may lead to an overestimate of lean mass. In this study, we employed quantitative magnetic resonance technique to evaluate body composition change following central administration of AgRP in a CKD mouse model. AgRP treatment improved energy expenditure, total body mass, fat mass, and lean body mass in CKD mouse. We also investigated the effect of CKD-associated cachexia on the signaling pathways leading to wasting in skeletal muscle, as well as whether these changes can be ameliorated by central administration of AgRP. AgRP treatment caused an overall decrease in proinflammatory cytokines, which may be one important mechanism of its effects. Muscle wasting in CKD may be due to the activation of proteolytic pathways as well as inhibition of myogenesis and muscle regeneration processes. Our results suggest that these aberrant pathological pathways leading to muscle wasting in CKD mice were ameliorated by central administration of AgRP.