bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating the Energy Budgets of Actively Predatory Fishes
Authors: Kerr S. R.
Published: April 2009

Where estimates of surplus energy accumulation are available, bioenergetic analysis of fish in nature requires estimates of the associated ration or metabolic levels. The estimation procedure described here is based upon direct coupling of ration intake with the activity metabolism subcomponent of total metabolism. Its primary advantage over other estimation procedures is in its simple, generalized handling of activity metabolism. Application of the method is illustrated for natural populations of cod, Gadus morhua, and haddock, Melanogrammus aeglefinus.Key words: bioenergetics, growth, metabolism, rations, cod, haddock
Bioconcentration of a Hexachlorobiphenyl in Great Lakes Planktonic Algae
Authors: Lederman Timoth C. , Rhee G-Yull
Published: April 2009

The bioconcentration of 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCB) was examined in the Great Lakes algae Fragilaria crotonensis, Ankistrodesmus falcatus, and Microcystis sp. The bioconcentration factors varied from species to species, whether they were expressed in terms of cell number, dry weight, cellular carbon, or cellular lipid. The factors were in the range of 105–106 and increased with decreasing biomass. The existence of a mucilage layer in F. crotonensis was associated with a twofold increase in the bioconcentration factor. Surface adsorption appeared to contribute only slightly to the bioaccumulation of HCB. HCB desorbed from all species but at a much slower rate than its adsorption.Key words: bioconcentration, bioaccumulation, polychlorinated biphenyls, hexachlorobiphenyl, adsorption, desorption, algae
Influence of a Hexachlorobiphenyl in Great Lakes Phytoplankton in Continuous Culture
Authors: Lederman Timoth C. , Rhee G-Yull
Published: April 2009

The influence of 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCB) on the growth of Great Lakes phytoplankters Fragilaria crotonensis, Ankistrodesmus falcatus, and Microcystis sp. was investigated in continuous culture under nutrient-sufficient and phosphate (P) limited conditions. Growth rate (μ) was inhibited only in F. crotonensis at cellular HCB concentrations as low as 4 × 10−8 ng/cell (0.8 μg/g dry weight) in nutrient-sufficient cultures; there appeared to be a dose–response relationship between cellular HCB and μ. Microcystis sp. and A. falcatus showed no inhibitory effect at cellular HCB levels up to 5 × 10−8 ng/cell (3.6 μg/g dry weight) and 30 × 10−8 ng/cell (11.5 μg/g dry weight), respectively. Under P-limited conditions HCB also affected F. crotonensis but not A. falcatus. The initial response of F. crotonensis to HCB addition was a significant increase in μ, followed by a sharp decline. In both nutrient-rich and P-limited F. crotonensis the cellular chlorophyll a (chl a) concentration decreased with the accumulation of HCB, yet the 14C assimilation rate per unit chl a increased. Cellular P concentration in the P-limited cells also decreased with the accumulation of HCB. Such responses were not observed in the other species.Key words: polychlorinated biphenyls, hexachlorobiphenyl, bioconcentration. Great Lakes, algae, continuous culture
Food, Feeding Habits, and Estimates of Daily Ration of the Shortfin Mako (Isurus oxyrinchus) in the Northwest Atlantic
Authors: Stillwell C. E. , Kohler N. E.
Published: April 2009

Analyses of the stomach contents of 399 male and female mako sharks (Isurus oxyrinchus) ranging from 67 to 328 cm are presented. Samples are from shark fishing tournaments held in New Jersey, New York, Rhode Island, and from longline catches taken between Cape Hatteras and the Grand Banks. Teleost remains occur in 67% of the stomachs with bluefish (Pomatomus saltatrix) constituting 77.5% of the diet by volume. Bluefish is the major inshore food item. Cephalopoda amount to 15% of the stomach contents by frequency of occurrence and are consumed primarily offshore. Consumption and diet are the same for both sexes. The average capacity of the stomach is 10% of the body weight. Estimates of daily ration average 2 kg (range from 1.4 to 2.7 kg). Makos may consume 4.3 to 14.5% of the available bluefish resource in the area between Cape Hatteras, NC, and Georges Bank.Key words: shortfin mako, Isurus oxyrinchus; elasmobranchs, food habits, stomach content analyses, daily ration, Pomatomus saltatrix, biomass
A Methodology for Estimating Area Fished for Baited Hooks and Traps Along a Ground Line
Authors: Eggers Douglas M. , Rickard Neil A. , Chapman Douglas G. , Whitney Richard R.
Published: April 2009

The methodology that estimates area fished for baited hooks or traps involves experimental fishing of strings of baited hooks or traps at different spacing along a ground line. This methodology enables expansion of catch per effort to a population estimate, when other methods may be impracticable. Experimentation and estimation procedures are given and the method is applied to data for prickly sculpin (Cottus asper), halibut (Hippoglossus stenolepis), and sablefish (Anoplopoma fimbria).Key words: baited hook, baited trap, stock assessment, fish density, longline, estimate
Optimal Utilization of a Variable Fish Supply
Authors: Silvert William
Published: April 2009

Successful exploitation of a fishery depends not only on the quantity of fish caught and processed, but also on the steadiness of supply. Too much variability in catch means that supplies will sometimes be inadequate, while at other times there will be too many fish to process, and the market will become glutted. Fisheries managers must therefore be prepared to make a trade-off between maximization of mean yield and minimization of the variance of this yield if the fishery is to function optimally. To do this they must understand the economic trade-offs that enter into the catching, processing, and marketing aspects of the fishery. This paper presents a strategy for coupling biological and economic models and illustrates how these questions can be quantified and integrated to arrive at a bioeconomically optimal management strategy.Key words: optimality, variability, fisheries management, sustainable yield
Factors Influencing Orthophosphate Turnover Times: a Comparison of Canadian and New Zealand Lakes
Authors: White E. , Payne G. , Pickmere S. , Pick F. R.
Published: April 2009

Fifty-five samples of lakewater from 21 New Zealand and 9 Canadian lakes were analyzed for dissolved phosphate, particulate phosphorus, and particulate nitrogen. The particulate N was used as an estimate of phytoplankton biomass and the ratio of particulate N to particulate P was used as an indicator of phosphorus sufficiency or deficiency within the biota. 32P-PO4-derived turnover times were found to be positively related to the size of the dissolved phosphate pool, negatively related to biomass, and were short where phosphorus deficiency existed. The amount of particulate nitrogen in the Canadian lake samples probably indicates an abundance of this nutrient in Canadian waters relative to that found in New Zealand. High seston N/P ratios in Canadian samples indicate a degree of phosphorus shortage in biota which is seen in few New Zealand waters.Key words: orthophosphate, turnover times, particulate phosphorus, particulate nitrogen, plankton biomass, phosphorus deficiency, Canadian lakes, New Zealand lakes
Predation of Sea Scallops (Placopecten magellanicus) by Lobsters (Homarus americanus) and Rock Crabs (Cancer irroratus) in Underwater Cage Enclosures
Authors: Jamieson G. S. , Stone H. , Etter M.
Published: April 2009

Predation studies in underwater cage enclosures on natural substrates were conducted in 1979 and 1980 to assess the propensity of adult American lobsters, Homarus americanus, and rock crabs, Cancer irroratus, to prey upon sea scallops, Placopecten magellanicus. In 1979, the initial prey by both predator species was large, embedded horse mussels (Modiolus modiolus). In the enclosure containing lobsters, this was followed by lobster cannibalism and, finally, when lobster density was reduced, predation on large sea scallops (80–110 mm shell height). No cannibalism or predation on large scallops occurred in the rock crab enclosure. In 1980, small scallops (40–55 mm shell height) were presented to lobsters and rock crabs; predation occurred regardless of predator density. Large sea scallops and unembedded horse mussels were consumed when crustacean densities approached natural levels. These studies demonstrate that small sea scallops and embedded horse mussels can be readily consumed by lobsters and rock crabs under field conditions, but that natural predation of large scallops by either rock crabs or lobsters is of lesser magnitude.Key words: sea scallops, crabs, lobsters, predation, prey selectivity
Application of X-ray Microanalysis for the Detection of Heavy Metals in Great Lakes Algae
Authors: Bistricki T. , Munawar M.
Published: April 2009

A combination of scanning electron miscroscopy and energy dispersive X-ray spectroscopy (SEM-EDX) was found to be a very effective tool for characterizing the heavy metal load of Great Lakes phytoflagellates, diatoms, and green algae, and for the surveillance of heavy metal pollution. The sensitivity and short generation time of nannoplankton and the speed of the described technique makes this procedure a useful aid in contaminants research.Key words: scanning electron microscopy, X-ray microanalysis, nannoplankton, heavy metals, algae, phytoflagellates, Great Lakes, contaminants, bioaccumulation
Influence of Age, Size, and Temperature on Metamorphosis in the Starry Flounder, Platichthys stellatus
Authors: Policansky David
Published: April 2009

The onset of metamorphosis of starry flounders (Platichthys stellatus) reared at the New England Aquarium was more strongly related to size than to age. For three of the eight crosses the regression of standard lengths (SL) of the progenies at metamorphosis on age was not different from 0 at the 10% significance level. For the other five the regression coefficients were negative and different from 0 at the 5% level but only 11.2% or less of the variation in SL at metamorphosis was accounted for by age. Progeny from one of the crosses were reared at two temperatures; at the higher temperature the time to metamorphosis was greatly reduced, but there was only a small change in the SL at metamorphosis.Key words: metamorphosis, age, size, development, demography, temperature, starry flounder
An Improved Chamber for in situ Measurement of Primary Productivity by Sea Ice Algae
Authors: Schrader G. C. , Horner R. , Smith G. F.
Published: April 2009

A modified chamber was designed for in situ measurement of carbon uptake of micro-algae growing on the underside of sea ice. The chamber, operated by SCUBA divers, accommodates a wider range of ice conditions, has better holding capability, and reduces sample loss during retrieval.Key words: Arctic Ocean, sea ice algae, primary productivity
SYNCHRONIZATION IN AN ARRAY OF HYBRID COUPLED NEURAL NETWORKS WITH MODE-DEPENDENT MIXED DELAYS AND MARKOVIAN SWITCHING
Authors: TANG YANG , QIU RUNHE , FANG JIAN-AN
Published: April 2009

In this letter, a general model of an array of N linearly coupled chaotic neural networks with hybrid coupling is proposed, which is composed of constant coupling, time-varying delay coupling and distributed delay coupling. The complex network jumps from one mode to another according to a Markovian chain with known transition probability. Both the coupling time-varying delays and the coupling distributed delays terms are mode-dependent. By the adaptive feedback technique, several sufficient criteria have been proposed to ensure the synchronization in an array of jump chaotic neural networks with mode-dependent hybrid coupling and mixed delays in mean square. Finally, numerical simulations illustrated by mode switching between two complex networks of different structure dependent on mode switching verify the effectiveness of the proposed results.
THE RESONANCE ESCAPE FACTOR AND DENSITY SPATIAL DISTRIBUTION OFLi670.970 nm RESONANCE LINES
Authors: HE JIAN , ZHANG QINGGUO , CHEN QINGDONG
Published: April 2009

In this letter, the resonance escape factors and spatial distribution of three resonance absorption lines that making up the Li 670.970 nm line are discussed theoretically, for both Lorentzian and Voigt profiles. The oscillator strength, the number density of the absorbing atoms in the ground state, and the optical depth in the line center are discussed also in the calculation. The results we calculated are in good agreement with the experimental results. This calculation will be significant in the research of plasma Li atom.
THE EFFECT OF MOLECULAR ORIENTATION TO SOLID–SOLID AND MELTING TRANSITIONS
Authors: YAZICI MUSTAFA , ÖZGAN ŞÜKRÜ
Published: April 2009

The thermodynamics of solid–solid and solid–liquid transitions are investigated with an account of the number of molecular orientation. The variations of the positional and orientational orders with the reduced temperature are studied. It is found out that orientational order parameter is very sensitive to the number of allowed orientation. The reduced transition temperatures, volume changes and entropy changes of the phase transitions and theoretical phase diagrams are obtained. The entropy changes of melting transitions for different numbers of allowed orientation of the present model are compared with the theoretical results and some experimental data. The quantitative predictions of the model are compared with experimental results for plastic crystals and agreement between predictions of the model and the experimental results are approximately good. Also, different numbers of allowed orientation D correspond to different experimental results HI , HBr , H 2 S for D = 2; HBr , CCl 4, HI for D = 4; C 2 H 12 for D = 6; CH 4, PH 3 for D = 20.
ADAPTIVE ℋ∞ SYNCHRONIZATION OF UNIFIED CHAOTIC SYSTEMS
Authors: PARK JU H. , JI D. H. , WON S. C. , LEE S. M.
Published: April 2009

In this paper, the problem of adaptive ℋ∞ synchronization for unified chaotic systems with unknown parameter and external disturbance is studied. It is noticed that this unified chaotic system contains the noted Lorentz, Lü and Chen systems. Based on Lyapunov theory and linear matrix inequality (LMI) formulation, the novel feedback controller with adaptive law is established to not only guarantee stable synchronization of both master and slave systems but also reduce the effect of external disturbance to an ℋ∞ norm constraint. A criterion for existence of the controller is given in terms of LMIs. Finally, a numerical example shows the effectiveness of the proposed method.
ARAGONITE TO CALCITE TRANSFORMATION STUDIES BY ESR OF Mn2+ IONS IN SINOTAIA INGALLSIANA
Authors: UDOMKAN NITINAI , LIMSUWAN PICHET
Published: April 2009

We have studied paramagnetic Mn 2+ ions present in the freshwater snail, Sinotaia ingallsiana (FS), Viviparus which are abundant in Thailand. The FS shells in our study were ground into fine powder. A set of seven samples was each then separately annealed for 2 hours in air atmosphere at 300°C, 400°C, 500°C, 600°C, 700°C, 800°C and 900°C, respectively. Our detailed ESR spectral analyses of FS show that Mn 2+ ions enter Ca 2+ sites during a biomineralization process. The hyperfine coupling constant (A) and zero-field splitting (D) in the ESR spectrum of Mn 2+ in calcite and aragonite were determined. The spreading of the non-central allowed transitions was analyzed and the experimental transitions were attributed. For calculating the hyperfine coupling constant, five methods for calculating the zero-field splitting, based on the analysis of the allowed and forbidden transitions, were provided. The values of the hyperfine coupling constant range from 87.50 to 89.00 G and those of the zero-field splitting range from 110.00 to 116.00 G.
NOVEL PROPERTIES IN OXIDE HETEROSTRUCTURES
Authors: GE CHEN , JIN KUI-JUAN , LU HUI-BIN , WANG CONG
Published: April 2009

A brief review of recent investigations in oxide heterostructures is presented. First, experimental results are shown. Positive colossal magnetoresistance with high sensitivities are obtained at low magnetic field (<1000 Oe) nearly at room temperature. Picoseconds photoelectric effects of the rise time ~ 210 ps and the half-maximum ~ 650 ps are also found in some oxide heterostructures. Furthermore, resistance switching characteristic and electric displacement-voltage hysteresis loops have been observed in BaTiO3-δ/ Si p–n heterostructures. Second, theoretical descriptions are also shown here. A model for the mechanism causing the positive colossal magnetoresistance has been established. Moreover, the transport properties and the important role played by oxygen vacancies are theoretically investigated in oxide heterostructures. In addition, an extended percolation model is well developed, with which the transport characteristic in oxide thin films can be well simulated based on the phase separation scenario. Notably, the interface effects play a crucial role in the multifunctional properties of the oxide heterostructures.
FIRST PRINCIPLES STUDY OF BORON SEGREGATION ON THE ${\rm Si}(111)(\sqrt{3} \times \sqrt{3}){\rm R}30^{\circ}$ SURFACE
Authors: ZAVODINSKY V. G. , CHUKUROV E. N. , KUYANOV I. A.
Published: April 2009

Segregation of boron on [Formula: see text] surface has been studied using the periodical calculations within the local density approximation. The obtained segregation energy (enthalpy) of about -1.9 eV is close to the published data of experimental studies and previous cluster semiempirical calculations. The influence of plane-wave basis set cutoff energy and the slab unit cell depth on the value of segregation energy has been investigated.
SURFACE MODIFICATION OF POLYETHYLENE (PE) BY THE DEPOSITION OF TITANIUM DIOXIDE (TiO2) NANOPARTICLES TO ENHANCE THE PHOTOCATALYTIC ACTIVITIES
Authors: PANDEY J. K. , KIM M. H. , CHUN D. M. , LEE C. S. , AHN S. H.
Published: April 2009

In recent years, there has been growing interest in the preparation of TiO 2-deposited materials for the application in different fields of photocatalytic activities, such as photocatalysis, dye-sensitized solar cells, antireflective coatings, and electro-chromic devices. TiO 2 particles were deposited on the PE surface by spraying method at room temperature. The deposition analysis was conducted by atomic force microscopy (AFM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FE-SEM) for monitoring the variation in morphology and different properties. It was found that the surface was deposited uniformly with higher concentration of particles and did not affect the inherent properties of polymers. The deposited TiO 2 particles favor the photodegradation of synthetic nonbiodegradable polymeric materials, which will ultimately decompose in the environment.
EFFECT OF SURFACE MODIFICATION ON THE PROPERTIES OF YAG–ZrB2 CERAMICS
Authors: SONG JIE-GUANG , LI SHI-BIN , JU YIN-YAN , DU DA-MING , WANG YU-WEI , ZHANG LIAN-MENG
Published: April 2009

ZrB 2 belongs to a class of ceramics defined ultra-high-temperature ceramics with extremely high melting temperatures; however, ZrB 2 ceramics is easily oxidized. To make ZrB 2 ceramics possess the better oxidation resistance in the air at high temperature, in this paper, the effect of surface modification on the properties of YAG– ZrB 2 ceramics were investigated. Fracture toughness of sintered ceramics with coated raw materials is higher than that of sintered ceramics with mixed raw materials under the same phase and phase content conditions. Oxidation layer thickness of sintered ceramics with coated raw materials is thinner than that of sintered ceramics with mixed raw materials. The results indicate that the sintered coated structure ceramics with coated raw materials help to increase the mechanical property and oxidation resistance of YAG– ZrB 2 ceramics.
PREPARATION OF HIGHLY SULFONATED ULTRA-THIN PROTON-EXCHANGE POLYMER MEMBRANES FOR PROTON EXCHANGE MEMBRANE FUEL CELLS
Authors: JIANG ZHONGQING , MENG YUEDONG , JIANG ZHONG-JIE , SHI YICAI
Published: April 2009

Sulfonated ultra-thin proton-exchange polymer membrane carrying pyridine groups was made from a plasma polymerization of styrene, 2-vinylpyridine, and trifluoromethanesulfonic acid by after-glow capacitively coupled discharge technique. Pyridine groups tethered to the polymer backbone acts as a medium through the basic nitrogen for transfer of protons between the sulfonic acid groups of proton exchange membrane. It shows that the method using present technology could effectively depress the degradation of monomers during the plasma polymerization. Spectroscopic analyses reveal that the obtained membranes are highly functionalized with proton exchange groups and have higher proton conductivity. Thus, the membranes are expected to be used in direct methanol fuel cells.
PHOTO-CATALYTIC PROPERTIES OF TiO2–Fe2O3–La2O3 NANO-COMPOSITE FILMS
Authors: LI JING , YAO MING-MING , ZHANG YING , YANG HUAI
Published: April 2009

Titanium dioxide doped Fe 3+ and La 3+ nano-composite films were prepared using the sol–gel method. The photo-catalytic properties were evaluated by photo-degradation of methyl orange in solution. Scanning electron microscope, X-ray diffraction, and energy dispersive spectrometer were used to characterize the TiO 2 film doped Fe 3+ and La 3+, indicating that the film has nano-structure, and mainly anatase crystal. It is proved that co-doped Fe 3+ and La 3+ can improve significantly the photo-catalytic properties of TiO 2 film due to the synergistic effect of the two ions.
COMPARATIVE STUDY ON THE IMMOBILIZATION OF LIPASE ON CHITOSAN GELS MODIFIED BY DIFFERENT HYDROPHOBIC GROUPS
Authors: DENG HONG-TAO , LIN YAN , WANG JUAN-JUAN , LIU ZHONG-YANG , MA MIAO , ZHENG FEI
Published: April 2009

The hydrophobic surface modification of chitosan gels (CS) was carried out using the amidating reaction of amido groups on a gel surface with propionic acid, stearic acid, and benzoic acid, respectively, activated by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Lipase from Candida rugosa was immobilized by adsorption on the nascent CS, propionyl-modified gels (PCS), stearyl-modified gels (SCS), and benzoyl-modified gels (BCS), respectively. The adsorption capacity and activity of immobilized lipase were investigated. It was found that the surface modification improved the adsorption capacity of lipase, and the activity retention of immobilized lipase increased from 52.34% for CS to 57.17%, 78.26% and 69.22%, respectively, for PCS, SCS, and BCS.
Satellite cell-mediated angiogenesis in vitro coincides with a functional hypoxia-inducible factor pathway
Authors: Rhoads R. P. , Johnson R. M. , Rathbone C. R. , Liu X. , Temm-Grove C. , Sheehan S. M. , Hoying J. B. , Allen R. E.
Published: April 2009

Muscle regeneration involves the coordination of myogenesis and revascularization to restore proper muscle function. Myogenesis is driven by resident stem cells termed satellite cells (SC), whereas angiogenesis arises from endothelial cells and perivascular cells of preexisting vascular segments and the collateral vasculature. Communication between myogenic and angiogenic cells seems plausible, especially given the number of growth factors produced by SC. To characterize these interactions, we developed an in vitro coculture model composed of rat skeletal muscle SC and microvascular fragments (MVF). In this system, isolated epididymal MVF suspended in collagen gel are cultured over a rat SC monolayer culture. In the presence of SC, MVF exhibit greater indices of angiogenesis than MVF cultured alone. A positive dose-dependent effect of SC conditioned medium (CM) on MVF growth was observed, suggesting that SC secrete soluble-acting growth factor(s). Next, we specifically blocked VEGF action in SC CM, and this was sufficient to abolish satellite cell-induced angiogenesis. Finally, hypoxia-inducible factor-1α (HIF-1α), a transcriptional regulator of VEGF gene expression, was found to be expressed in cultured SC and in putative SC in sections of in vivo stretch-injured rat muscle. Hypoxic culture conditions increased SC HIF-1α activity, which was positively associated with SC VEGF gene expression and protein levels. Collectively, these initial observations suggest that a heretofore unexplored aspect of satellite cell physiology is the initiation of a proangiogenic program.
Endofacial competitive inhibition of the glucose transporter 1 activity by gossypol
Authors: Pérez Alejandra , Ojeda Paola , Valenzuela Ximena , Ortega Marcela , Sánchez Claudio , Ojeda Lorena , Castro Maite , Cárcamo Juan G. , Rauch M. Cecilia , Concha Ilona I. , Rivas Coralia I. , Vera Juan C. , Reyes Alejandro M.
Published: April 2009

Gossypol is a natural disesquiterpene that blocks the activity of the mammalian facilitative hexose transporter GLUT1. In human HL-60 cells, which express GLUT1, Chinese hamster ovary cells overexpressing GLUT1, and human erythrocytes, gossypol inhibited hexose transport in a concentration-dependent fashion, indicating that blocking of GLUT1 activity is independent of cellular context. With the exception of red blood cells, the inhibition of cellular transport was instantaneous. Gossypol effect was specific for the GLUT1 transporter since it did not alter the uptake of nicotinamide by human erythrocytes. Gossypol affects the glucose-displaceable binding of cytochalasin B to GLUT1 in human erythrocyte ghost in a mixed noncompetitive way, with a Kivalue of 20 μM. Likewise, GLUT1 fluorescence was quenched ∼80% by gossypol, while Stern-Volmer plots for quenching by iodide displayed increased slopes by gossypol addition. These effects on protein fluorescence were saturable and unaffected by the presence of d-glucose. Gossypol did not alter the affinity of d-glucose for the external substrate site on GLUT1. Kinetic analysis of transport revealed that gossypol behaves as a noncompetitive inhibitor of zero- trans (substrate outside but not inside) transport, but it acts as a competitive inhibitor of equilibrium-exchange (substrate inside and outside) transport, which is consistent with interaction at the endofacial surface, but not at the exofacial surface of the transporter. Thus, gossypol behaves as a quasi-competitive inhibitor of GLUT1 transport activity by binding to a site accessible through the internal face of the transporter, but it does not, in fact, compete with cytochalasin B binding. Our observations suggest that some effects of gossypol on cellular physiology may be related to its ability to disrupt the normal hexose flux through GLUT1, a transporter expressed in almost every kind of mammalian cell and responsible for the basal uptake of glucose.
Integration of skeletal muscle resistance arteriolar reactivity for perfusion responses in the metabolic syndrome
Authors: Frisbee Jefferson C. , Hollander John M. , Brock Robert W. , Yu Han-Gang , Boegehold Matthew A.
Published: April 2009

Previous study suggests that with evolution of the metabolic syndrome, patterns of arteriolar reactivity are profoundly altered and may constrain functional hyperemia. This study investigated interactions between parameters of vascular reactivity at two levels of resistance arterioles in obese Zucker rats (OZR), translating these observations into perfusion regulation for in situ skeletal muscle. Dilation of isolated and in situ resistance arterioles from OZR to acetylcholine, arachidonic acid (AA), and hypoxia (isolated arterioles only) were blunted vs. lean Zucker rats (LZR), although dilation to adenosine was intact. Increased adrenergic tone (phenylephrine) or intralumenal pressure (ILP) impaired dilation in both strains (OZR>LZR). Treatment of OZR arterioles with Tempol (superoxide dismutase mimetic) or SQ-29548 (prostaglandin H2/thromboxane A2 receptor antagonist) improved dilator reactivity under control conditions and with increased ILP, but had minimal effect with increased adrenergic tone. Arteriolar dilation to adenosine was well maintained in both strains under all conditions. For in situ cremasteric arterioles, muscle contraction-induced elevations in metabolic demand elicited arteriolar dilations and hyperemic responses that were blunted in OZR vs. LZR, although distal parallel arterioles were characterized by heterogeneous dilator and perfusion responses. α-Adrenoreceptor blockade improved outcomes at rest but had minimal effect with elevated metabolic demand. Treatment with Tempol or SQ-29548 had minimal impact at rest, but lessened distal arteriolar perfusion heterogeneity with increased metabolic demand. In blood-perfused gastrocnemius of OZR, perfusion was constrained primarily by adrenergic tone, while myogenic activation and endothelium-dependent dilation did not appear to contribute significantly to ischemia. These results of this novel, integrated approach suggest that adrenergic tone and metabolic dilation are robust determinants of bulk perfusion to skeletal muscle of OZR, while endothelial dysfunction may more strongly regulate perfusion distribution homogeneity via the impact of oxidant stress and AA metabolism.
Marinobufagenin causes endothelial cell monolayer hyperpermeability by altering apoptotic signaling
Authors: Uddin Mohammad N. , Horvat Darijana , Childs Ed W. , Puschett Jules B.
Published: April 2009

Marinobufagenin (MBG) is an endogenous mammalian cardiotonic steroid that is involved in the inhibition of the sodium pump Na+/K+-ATPase. Increased plasma levels of MBG have been reported in patients with preeclampsia. MBG increases microvascular barrier permeability in an animal model of preeclampsia. However, the mechanism by which MBG impairs endothelial permeability is unknown. We utilized rat lung microvascular endothelial cells (RLMEC) to examine alterations in MBG-induced monolayer permeability and the effect of MBG on the phosphorylation status of ERK1/2, Jnk, and p38. Apoptosis was evaluated by examining alterations in caspases 3/7, 8, and 9 and annexin-V staining. We also examined the effect of MBG on the endothelial adherens junctions of the RLMEC monolayer. MBG inhibited the proliferation, and increased the monolayer permeability, of RLMEC. These actions of MBG were attenuated by ERK, p38, and pan caspase inhibition. MBG significantly decreased the phosphorylation of ERK1/2 and activated the phosphorylation of Jnk and p38. MBG also significantly increased the expression of caspases 3/7, 8, and 9, indicating the activation of apoptosis. MBG-induced apoptosis signaling was not observed in cells pretreated with a p38 inhibitor. MBG treatment induced the disruption of endothelial cell junctions. This effect was prevented by a pan caspase inhibitor. In conclusion, 1) MBG induced an impairment of RLMEC proliferation; 2) the bufadienolide also caused endothelial hyperpermeability; and 3) these effects of MBG were mediated by the downregulation of ERK1/2, the upregulation of Jnk and p38, by the activation of apoptosis, and by the disruption of endothelial cell junctions.
AT1 receptor activation regulates the mRNA expression of CAT1, CAT2, arginase-1, and DDAH2 in preglomerular vessels from angiotensin II hypertensive rats
Authors: Hultström Michael , Helle Frank , Iversen Bjarne M.
Published: April 2009

Previously, we found increased expression of l-arginine metabolizing enzymes in both kidneys from two-kidney, one-clip (2K1C) hypertensive rats (Helle F, Hultstrom M, Skogstrand T, Palm F, Iversen BM. Am J Physiol Renal Physiol 296: F78–F86, 2009). In the present study, we investigate whether AT1 receptor activation can induce the changes observed in 2K1C. Four groups of rats were infused with 80 ng/min ANG II or saline for 14 days and/or given 60 mg·kg−1·day−1 losartan. Gene expression was studied in isolated preglomerular vessels by RT-PCR. Dose-responses to ANG II were studied in isolated preglomerular vessels with and without acute NOS inhibition [10−4 mol/l NG-nitro-l-arginine methyl ester (l-NAME)]. Expressions of endothelial nitric oxide synthase (eNOS), caveolin-1, and arginase-2 were not changed by ANG II infusion. CAT1 (0.3 8 ± 0.07 to 0.73 ± 0.12, P < 0.05), CAT2 (1.14 ± 0.29 to 2.74 ± 0.48), DDAH2 (1.09 ± 0.27 to 2.3 ± 0.46), and arginase-1 (1.08 ± 0.17 to 1.82 ± 0.22) were increased in ANG II-infused rats. This was prevented by losartan treatment, which reduced the expression of eNOS (0.97 ± 0.26 to 0.37 ± 0.11 in controls; 0.8 ± 0.16 to 0.36 ± 0.1 in ANG II-infused rats) and caveolin-1 (2.49 ± 0.59 to 0.82 ± 0.24 in controls and 2.59 ± 0.61 to 1.1 ± 0.25 in ANG II-infused rats). ANG II (10−10 mol/l) caused vessels from ANG II-infused animals to contract to 53 ± 15% of baseline diameter and 90 ± 5% of baseline diameter in controls ( P < 0.05) and was further enhanced by l-NAME to 4 ± 4% of baseline diameter ( P < 0.05). In vivo losartan treatment reduced the reactivity of isolated vessels to 91 ± 2% of baseline in response to 10−7 mol/l ANG II compared with 82 ± 3% in controls ( P < 0.05) and prevented the increased responsiveness caused by ANG II infusion. In conclusion, CAT1, CAT2, DDAH2, and arginase-1 expression in renal resistance vessels is regulated through the AT1 receptor. This finding may be of direct importance for NOS and the regulation of preglomerular vascular function.
Basic fibroblast growth factor causes urinary bladder overactivity through gap junction generation in the smooth muscle
Authors: Imamura Masaaki , Negoro Hiromitsu , Kanematsu Akihiro , Yamamoto Shingo , Kimura Yu , Nagane Kentaro , Yamasaki Toshinari , Kanatani Isao , Ito Noriyuki , Tabata Yasuhiko , Ogawa Osamu
Published: April 2009

Overactive bladder is a highly prevalent clinical condition that is often caused by bladder outlet obstruction (BOO). Increased coupling of bladder smooth muscle cells (BSMC) via gap junctions has been hypothesized as a mechanism for myogenic bladder overactivity in BOO, although little is known about the regulatory system underlying such changes. Here, we report the involvement of basic fibroblast growth factor (bFGF) and connexin 43, a bladder gap junction protein, in bladder overactivity. BOO created by urethral constriction in rats resulted in elevated bFGF and connexin 43 levels in the bladder urothelium and muscle layer, respectively, and muscle strips from these bladders were more sensitive than those from sham-operated controls to a cholinergic agonist. In vitro bFGF treatment increased connexin 43 expression in cultured rat BSMC via the ERK 1/2 pathway. This finding was supported by another in vivo model, where bFGF released from gelatin hydrogels fixed on rat bladder walls caused connexin 43 upregulation and gap junction formation in the muscle layer. Bladder muscle strips in this model showed increased sensitivity to a cholinergic agonist that was blocked by inhibition of gap junction function with α-glycyrrhetinic acid. Cystometric analyses of this model showed typical features of detrusor overactivity such as significantly increased micturition frequency and decreased bladder capacity. These findings suggest that bFGF from the urothelium could induce bladder hypersensitivity to acetylcholine via gap junction generation in the smooth muscle, thereby contributing to the myogenic overactivity of obstructed bladders.
Motor unit control and force fluctuation during fatigue
Authors: Contessa Paola , Adam Alexander , De Luca Carlo J.
Published: April 2009

During isometric contractions, the fluctuation of the force output of muscles increases as the muscle fatigues, and the contraction is sustained to exhaustion. We analyzed motor unit firing data from the vastus lateralis muscle to investigate which motor unit control parameters were associated with the increased force fluctuation. Subjects performed a sequence of isometric constant-force contractions sustained at 20% maximal force, each spaced by a 6-s rest period. The contractions were performed until the mean value of the force output could not be maintained at the desired level. Intramuscular EMG signals were detected with a quadrifilar fine-wire sensor. The EMG signals were decomposed to identify all of the firings of several motor units by using an artificial intelligence-based set of algorithms. We were able to follow the behavior of the same motor units as the endurance time progressed. The force output of the muscle was filtered to remove contributions from the tracking task. The coefficient of variation of the force was found to increase with endurance time ( P < 0.001, R2 = 0.51). We calculated the coefficient of variation of the firing rates, the synchronization of pairs of motor unit firings, the cross-correlation value of the firing rates of pairs of motor units, the cross-correlation of the firing rates of motor units and the force, and the number of motor units recruited during the contractions. Of these parameters, only the cross-correlation of the firing rates ( P < 0.01, R2 = 0.10) and the number of recruited motor units ( P = 0.042, R2 = 0.22) increased significantly with endurance time for grouped subjects. A significant increase ( P < 0.001, R2 = 0.16) in the cross-correlation of the firing rates and force was also observed. It is suggested that the increase in the cross-correlation of the firing rates is likely due to a decrease in the sensitivity of the proprioceptive feedback from the spindles.
Evaluation of the Thickness in Nanolayers Using the Transfer Matrix
Method for Modeling the Spectral Reflectivity
Authors: González-Ramírez Juan E. , Fuentes Juan , Hernández Luis C. , Hernández Luís
Published: April 2009

The reflectivity spectra have been traditionally used to determine the thicknesses in semiconductor films. However, thicknesses of nanofilms are not easy to evaluate because the interference fringes are not visible in the transparent region. In this paper, we present a computed method based on the transfer matrix (TM) which is used to match the calculated and experimental room temperature reflectivity spectra of the ZnTe/GaAs films and to determine its thickness film values afterwards. The TM method needs only to know refraction indices and absorption coefficients as a function of wavelength for the film and the substrate. The thickness nanofilms evaluated by our method are in agreement with the values measured by ellipsometry, Rutherford backscattering spectroscopy and transmission electron microscopy techniques. The present procedure extends the application of the standard spectral reflectance technique to determine semiconductor nanolayer thicknesses.
Suppression of Adrenocorticotrophic Hormone Secretion by Simultaneous Antagonism of Vasopressin 1b and CRH-1 Receptors on Three Different Stress Models
Authors: Ramos Adriana T. , Troncone Lanfranco R.P. , Tufik Sergio
Published: April 2009

Background/Aims: Corticotrophin-releasing hormone (CRH), adrenocorticotrophic hormone (ACTH) and corticosterone are secreted during stress. These mediators may be involved in anxiety, depression and post-traumatic stress disorder, therefore antagonists have been developed to treat such conditions. Methods: The non-peptide CRH receptor type 1 antagonist CP154,526 and the vasopressin receptor type 1b antagonist SSR149415 were used to suppress the secretion of ACTH induced by ether exposure, forced swimming and restraint in adult male Wistar rats. Doses ranged from 3 to 60 mg/kg s.c. (controls with vehicle) alone or in combination, in varying time schedules to assess the duration and effectiveness of treatments. Results: Stressors increased plasma ACTH by 2.5- to 5-fold in control rats. SSR149415 at doses of 30 mg/kg was more effective at suppressing ACTH secretion after ether exposure and restraint but was ineffective against forced swimming. CP154,526 mildly affected ACTH rise after restraint at doses of 30 mg/kg. The combination of both antagonists at doses of 30 mg/kg effectively blocked the rise in plasma ACTH in all three stresses. The drug effects lasted less than 6 h. Conclusion: We demonstrated for the first time that simultaneous blockade of both vasopressin 1b and CRH-R1 receptors effectively abolish the ACTH response to physical and psychological stress modalities.
Group Structure and Physical Characteristics of Simakobu Monkeys (Simias concolor) on the Mentawai Island of Siberut, Indonesia
Authors: Hadi Susilo , Ziegler Thomas , Hodges J. Keith
Published: April 2009

We present data on group structure and physical characteristics from free-ranging Simias concolor. Mean group size (n = 3) was 8.7 ± 1.1 individuals with an average adult male:female sex ratio of 1:3. All individuals were sexed and allocated into three categories (infants, juveniles plus subadults and adults) on the basis of their physical development. Within age categories, head-body lengths ranged from 19.6 to 25, 34 to 44 and 42 to 53 cm. Corresponding body weights ranged from 0.5 to 0.9, 2.35 to 4.4 and 5.2 to 7.85 kg, respectively; on average adult males were 13% larger and 23% heavier than adult females. Results indicate that for S. concolor living in undisturbed habitat (i) group sizes are larger than previously reported and (ii) polygyny is the most likely mating system. Both results support an earlier proposal that group size and social organization in Simakobu monkey are related to the degree of habitat disturbance.
Structure-Function Relationship of 3-Phosphoglycerate Analogues with Platelet Aggregation and Thromboxane A2 Formation
Authors: Iatridis P.G. , Hadd H. , Kotrotsou M. , Ling-Indeck L. , Iatridis S.G.
Published: April 2009

We have studied the effects of 2,3-diphosphoglycerate (2,3-DPG), 3-phospho-glycerate (3-PG), 3-phosphoglyceraldehyde (3-PGA), 2-phosphoglycerate (2-PG) and β-glycerol phosphate (β-GP) on platelet aggregation and on thromboxane B2 (TXB2) formation. The results show that 2,3-DPG, 3-PG, and 3-PGA inhibited platelet aggregation and TXB2 formation induced by norepinephrine, ADP, epinephrine, and collagen; but they also induced platelet aggregation and TXB2 formation in the presence of subthreshold concentrations of Na arachidonate. 2-PG and β-GP were inactive. The results also show that there is a structure-function relationship between 2,3-DPG, 3-PG, and 3-PGA with platelet aggregation phenomena and prostaglandin synthesis.
Effect of Single-Dose Aspirin on TXA2 and PGI2 Cyclooxygenases in vivo
Authors: Zaragoza Rosemary , Le Breton Guy C.
Published: April 2009

The present study investigated the sensitivities of the thromboxane A2 (TXA2) cyclooxygenase and the prostacyclin (PGI2) cyclooxygenase to aspirin using an in vivo animal model. In this model, arachidonic acid (AA) was administered to mice via cardiac puncture, and plasma levels of thromboxane B2 (TXB2) and 6-keto prostaglandin F1α (6-keto PGF1α) were determined. Infusion of AA (5, 10, 25 and 50 mg/kg) resulted in a dose-dependent increase in both TXB2 and 6-keto PGF1α. Pretreatment with aspirin resulted in a dose-dependent and parallel decrease in TXB2 and 6-keto PGF1α production. This nonselective inhibition occurred at all doses of aspirin (1, 10 and 50 mg/kg) and at all levels of cyclooxygenase activity (5–50 mg/kg AA). These results indicate that the TXA2 and PGI2 cyclooxygenase enzymes are equally sensitive to inhibition by a single dose of aspirin.
Treatment of Deep Venous Thrombosis with a Very Low Molecular Weight Heparin Fragment (CY 222)
Authors: Janvier G. , Winnock S. , Dugrais G. , Vallet A. , Dardel E. , Serisé J.M. , Calen S. , Vergnes C. , Toulemonde F.
Published: April 2009

Thirty patients presenting with phlebographically confirmed deep venous thrombosis were treated with a very low molecular weight heparin fragment (CY 222) in an open and prospective phase-2 trial. A uniform dosage of 750 IC anti-factor Xa units/kg/day was administered subcutaneously for 10 days or more to patients whose thromboses were categorized as postsurgical (17 cases) or medical (13 cases). The clinical symptoms of venous thrombosis diminished in 93% of the patients overall. The extent of vascular clearing was assessed by an original scoring system which compared the pre- and posttreatment phlebo-graphies. The effect of treatment was globally rated ‘very good’ (more than 75 % lysis) in 37% of the patients, ‘good’ (about 50% lysis) in 40% and ‘poor’ (0–25% lysis) in 17%; the phle-bographic thrombosis worsened in 6.6%. Little change occurred in laboratory tests exploring thrombolysis, but a strong anti-factor Xa activity was detected.
Influence of L-Ascorbic Acid, Blood Cells and Components on Protein Adsorption/Desorption on Polycarbonate
Authors: Sharma Chandra P. , Chandy Thomas
Published: April 2009

In a previous study we have shown that vitamin C has some effect on the polymer surface by adsorption to it, which would probably affect the protein adsorption and platelet adhesion. The present work has been extended to demonstrate the influence of vitamin C on the kinetics of protein-polymer interaction, using labeled proteins, in the presence and absence of red blood cells, platelets and white blood cells. It appears that vitamin C causes an increase in albumin surface concentration compared to bare substrate which seems to decrease slightly in the presence of blood cells. On the other hand, the infusion of vitamin C to the fibrinogen blood cells system dramatically inhibits the fibrinogen surface binding. The role of L-ascorbic acid to reduce the protein adsorption in the presence of blood cells is discussed by taking into account (a) the interaction of vitamin C with the polymer surface, (b) the interaction of vitamin C with the proteins and cellular membrane, and (c) the interaction of proteins and cells with the polymer itself. The effect of various blood components also seems to be important, and slight differences in the adsorption pattern of proteins are observed in the presence of urea, creatinine, bilirubin, Fe+++ ion and zinc at normal blood levels.
Corynebacterium parvum, but not BCG, Induces Elevations in Plasma Proteinase Activity Similar to Those Observed in Tumor-Bearing Mice
Authors: Hart David A.
Published: April 2009

Intraperitoneal administration of Corynebacterium parvum to BALB/c, C57B1/6 or C3H/HeJ mice lead to the induction of elevated levels of neutral proteinase activity (125I-caseinolytic activity) similar to those observed previously in animals bearing the BCL1 leukemia or the B16-F10 melanoma. Enhanced activity reached a peak at 7–14 days postin-jection of the C. parvum and then gradually returned to normal levels by 20–25 days postin-jection. Increased plasma proteinase activity could be induced by C. parvum whole cells or the pyridine extract residue of C. parvum but not by BCG or the pyridine extract of C. parvum. BCG did not interfere with the induction of elevated levels of activity by C. parvum. Splenectomized animals responded the same as normal mice indicating that the splenomegaly accompanying the onset of increased plasma proteinase activity was not responsible for the changes. Administration of C. parvum via a subcutaneous site rather than intraperitoneally failed to induce systemic changes in proteinase activity while still inducing splenomegaly. Treatment of animals with C. parvum before or after transplantation of the BCL1 leukemia or the B16-F10 melanoma failed to alter the course of the disease or enhance the increased proteinase activity of plasma over that observed in plasma from animals bearing tumors alone. These observations support the hypothesis that the induction of disturbances in plasma proteinase activity in tumor-bearing animals is due to alterations in host systems and that C. parvum, in contrast to BCG, contains components which can mimic the effect of some tumors on host systems.
Severe Platelet Dysfunction in a Patient with Autoantibodies against Membrane Glycoproteins IIb-IIIa
Authors: Balduini C.L. , Grignani G. , Sinigaglia F. , Bisio A. , Pacchiarini L. , Scalabrini Rota , Balduini C. , Mauri C. , Ascari E.
Published: April 2009

A young women affected by Hodgkin’s disease developed chronic autoimmune thrombocytopenic purpura. Splenectomy induced normalization of her platelet count, but hemorrhagic symptoms did not disappear. The patient’s platelets did not aggregate in response to collagen and ADP and the IgG fraction of the patient’s plasma induced the same defect in normal platelets. The women’s IgG recognized glycoproteins IIb and IIIa of normal platelet membranes. Prednisone therapy induced the disappearance of bleeding symptoms and the normalization of platelet aggregation