bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Solution Virus Capture Assay Helps Deconstruct Heterogeneous Antibody Recognition of Human Immunodeficiency Virus Type 1
Authors: Leaman Daniel P. , Kinkead Heather , Zwick Michael B.
Published: January 2010

Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) on whole virions is heterogeneous, so molecular analysis of Env with monoclonal antibodies (MAbs) is challenging. Virus capture assays (VCAs) involving immobilized MAbs are typically used, but these assays suffer from immobilization artifacts and do not provide binding constants. Furthermore, we show here that certain HIV-1 neutralizing MAbs, including 2G12, 4E10, 2F5, Z13e1, and D5, will capture virion particles completely devoid of Env. We modified the VCA such that MAbs and virions are incubated in solution, and unbound MAbs are removed prior to the capture step. This modification nearly eliminated evidence of Env-independent binding by MAbs to virions and allowed determination of apparent affinity constants in solution. Three important qualitative observations were further revealed. First, neutralizing MAbs 2F5, 4E10, and Z13e1 against the membrane-proximal external region (MPER) of HIV-1 gp41 were found to capture virions efficiently only if a significant amount of uncleaved gp160 or synthetic MPER peptide was present. Second, we show how non-native forms of Env vary by Env genotype and that Env from HIV-1
JR-FL
is more homogeneously trimeric than that from HIV-1
JR-CSF
. Third, we determined that Env containing all or parts of gp41, including uncleaved gp160, binds spontaneously to free virions. This exogenous Env is an indiscriminate molecular “bridge” between Env-specific Ab and virions and can affect VCA analyses, particularly using pseudotyped virions. Heterogeneity in Env from endogenous and exogenous sources might also subvert humoral immunity to HIV-1, so in-solution VCAs may help to dissect this heterogeneity for vaccine design purposes.
Pipeline plough performance in sand waves. Part 1: model testing
Authors: Bransby Mark Fraser , Brown Michael , Hatherley Andrew , Lauder Keith
Published: January 2010

Offshore pipelines are often buried in the seabed by ploughing a trench, placing the pipe at the base, and then backfilling. The ploughing operation is critical in terms of cost and project time, with increased risk due to uncertain soil conditions or geohazards. One problem that can be encountered is the presence of sand waves or megaripples on the seabed surface. This may affect the progress of the plough, prevent the plough from generating a level trench or modify the size of the spoil heaps for backfilling. These aspects have been investigated by conducting a series of small-scale model tests in the laboratory. These have revealed information about the plough kinematics and the resulting trench conditions when ploughing in sand waves with different wavelengths and amplitudes. It is shown that it may be possible to plough through regions of sand waves and estimate likely plough performance by knowing the sand wavelength and amplitude relative to the plough size.
Geotechnical characteristics of large rapid rock slides
Authors: Glastonbury James , Fell Robin
Published: January 2010

Based on the analysis of 51 case studies of large rapid rock slides, for a landslide to travel rapidly after failure there has to be a significant loss of strength on the basal surface of rupture, lateral margins, and (or) internally within the slide mass, or the factor of safety has to be maintained below 1.0 after failure by high groundwater pressures. Internally sheared compound slides and translational slides may all travel rapidly depending on their detailed geotechnical and geometric characteristics. The characteristics of these landslides that suggest an increased likelihood of rapid failure have been identified. All the rapid rock slides examined in this study involved relatively high-strength rock masses. Most cases were considered to be first-time landslides, largely involving brittleness on the basal rupture surface. However, there were some cases considered to be reactivated or active landslides on pre-sheared rupture surfaces. For this latter group, the loss of strength leading to rapid landsliding was associated with brittle internal deformation or lateral margins.
Inoculation studies of lodgepole pine with Alberta isolates of the Armillariamellea complex
Authors: Mallett K. I. , Hiratsuka Y.
Published: January 2010

Two-year-old lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) seedlings were each inoculated with one of 12 isolates of the Armillariamellea complex. All isolates were pathogenic but differed in the amounts of infection and mortality that they caused. An isolate of A. mellea s.str. and four Alberta isolates of North American biological species V (NABS V) caused the most mortality; however. A. mellea s.str. killed seedlings more quickly than NABS V. Seven Alberta isolates of NABS I infected and killed relatively few seedlings compared with NABS V and A. mellea s.str.
Jack pine site quality in relation to soil and topography in north central Ontario
Authors: Schmidt Margaret G. , Carmean Willard H.
Published: January 2010

Site index for jack pine (Pinusbanksiana Lamb.) was determined by stem analysis using dominant and codominant trees on each of 99 site plots located in mature, well-stocked, even-aged jack pine stands. Plots located on four major glacial soil groups showed a wide range of site index within each soil group. Separate multiple regression analysis showed that site index was significantly related to different soil and topographic features for each soil group: (i) for morainal soils shallow to bedrock (< 1.0 m deep) (R2 = 0.83), depth to bedrock and coarse fragment content; (ii) for deep morainal soils (R2 = 0.65), depth to root-restricting layer, coarse fragment content, and clay content; (iii) for outwashed glacial sands (R2 = 0.65), depth to root-restricting layer and slope steepness; and (iv) for glacial lacustrine soils (R2 = 0.75), thickness of A horizon and pH of the BC horizon. These results indicate that site quality for jack pine on each of these four general soil groups is related to soil features associated with the quantity and quality of soil most favorable for root development. Results are illustrated by trend graphs, and site index prediction tables are given for each of the four soil groups.
Seed dispersal, seedling emergence, and early survival of Larixlaricina (DuRoi) K. Koch in the Tanana Valley, Alaska
Authors: Brown K.R. , Zobel D.B. , Zasada J.C.
Published: January 2010

The seasonal and spatial patterns of seed release, germling emergence, and early survival of Larixlaricina (DuRoi) K. Koch were studied in 1980–1981 near Fairbanks, Alaska. Dispersal was studied on one wetland site. Seedling emergence and 1-year survival were studied on three wetland microsite types (troughs, feathermoss, and tussock tops, located at increasing elevations above permafrost) and in mineral soil and undisturbed feathermoss seedbeds in a mature Piceaglauca stand of alluvial origin. Approximately 95% of the viable Larix seed from the 1980 cone crop fell by November 1980. Spatial distribution of seed away from the stand was erratic because of variable winds and the presence of a single Larix away from the stand edge. Average dispersal distances were less than those reported for other coniferous species. Emergence and early survival in both site types were affected by seedbed type. In the alluvial stand, germination and 1-year survival were greater on mineral seedbeds than on feathermoss. Emergence began in mid-July, well after minimum temperatures required for germination had been reached; timing appeared to be related to differences in volumetric moisture contents of the two seedbed types. Although cumulative totals of emergence and mortality did not differ between microsite types in the wetland, seasonal patterns of each differed with microsite. Emergence in troughs was delayed until early July by cold seedbed temperatures; increased precipitation in mid to late July raised the water table and flooded newly emerged seedlings in trough microsites but moistened feathermoss sufficiently to promote germination. Variation in emergence and mortality was high within a given microsite type.
Precipitation and throughfall chemistry in Pinuscontorta ssp. latifolia ecosystems, southeastern Wyoming
Authors: Fahey Timothy J. , Yavitt Joseph B. , Joyce Greg
Published: January 2010

Precipitation and throughfall quantity and chemistry were measured in several Pinuscontorta ssp. latifolia ecosystems in southeastern Wyoming. Bulk deposition (open collector) was somewhat enriched chemically in comparison with wetfall (shielded collector), suggestive of dry deposition. With the exception of low S concentrations, atmospheric chemistry was comparable to other continental locations in North America. Concentrations of most solutes were much higher in canopy throughfall than rainfall. Canopy evaporation accounted for a 27% increase of dissolved solids in throughfall, the remaining differences being attributed to canopy leaching and washing of dryfall. Throughfall was most enriched in K+, Mg2+, and organic anions, indicating the importance of canopy leaching. Very high spatial variation was observed within the forests, precluding the detection of annual or site differences in throughfall chemistry. Our estimates of dry deposition to the lodgepole pine ecosystem were lower than for more polluted regions of eastern North America. Except for SO42−, wetfall supplied larger amounts of the major elements than dry deposition. Canopy leaching was a major flux pathway in these ecosystems, particularly for K+, Mg2+, and SO42−.
Experimental design and evaluation of a peatland drainage system for forestry by optimization of synthetic hydrographs
Authors: Tóth József , Gillard Don
Published: January 2010

A ditch system was designed, constructed, and evaluated on a 1-km2 experimental plot in peat-covered wetland in Slave Lake Forest, Alberta, Canada, during 1981–1985. The purpose of the experiment was the development of techniques and procedures for the design of drainage systems for water-table control in large tracts of forested peatlands of northern Alberta, in order to enhance tree growth. The technical objective of the envisaged drainage systems is to prevent the water table from rising above a specified depth, or drainage norm νm, below the land surface, for a continuous time interval longer than a specified flood duration limit λm, during the growing season. The position of the water table and the rate and amplitude of its fluctuations in a ditched area depend on the environmental parameters (K, hydraulic conductivity; S*, field coefficient of water-table response to precipitation; z, depth to the first effectively impermeable stratum; P, pattern of daily rainfall) the design parameters (L, ditch spacing; u, ditch depth), and at later stages of drainage, the effect of the tree stand. The objective of the design is, therefore, to determine appropriate values of L and u as functions of the environmental parameters to be used in the construction of operational drainage systems. The central component of the design procedure is the optimization of synthetic hydrographs. The synthetic hydrograph is a graphical representation of calculated time series of the water table's fluctuations reflecting the effect of discrete rainfall events under specified drainage conditions. Synthetic hydrographs were calculated with the U.S. Bureau of Reclamation drain spacing formula adapted here for daily rainfall events and ranges of estimated environmental and assumed design parameters. An experimental drainage system was constructed with preliminary design parameters that were expected to satisfy the criteria νm and λm. In addition, 14 water-table observation wells and a rain gauge were installed and operated for two summers. Synthetic hydrographs were then computed using the actually implemented design parameters, the actual rainfall pattern and a fixed z value, leaving K and S* as the only unknown variables. Those K and S* values giving the best approximation of calculated to observed hydrographs were considered to represent the effective field values and were used in turn to calculate the final design parameters, again by hydrograph matching. Final values for K and S* for two subregions of the experimental plot were found to be K1 = 0.37 m/d, S1* = 0.13; and K2 = 0.26 m/d, S2* = 0.11. For subregion No. 2 a ditch spacing L = 25 m and ditch depth u = 0.9 m satisfy the stipulated drainage norm νm = 0.4 m and flood duration limit λm = 14 days, using P1962, which was the wettest year for the last 28 years in the region.
Use of a video-imaging system for estimating leaf surface area of Pinussylvestris seedlings
Authors: Diebolt Kent S. , Mudge Kenneth W.
Published: January 2010

A method is described for a rapid, nondestructive estimation of the surface area of the shoot system of intact pine seedlings. A video camera and image analyzer were used to quantify the area of a video image of pine seedling shoots. Surface area values were displayed in dimensionless units, referred to as silhouette area. Silhouette area was significantly correlated with several other methods of estimating needle surface area, including dry weight, calculation based on measurement of linear dimensions, volume displacement, and optical planimetry. Correspondence between dry weight, or surface area estimates based on dry weight, and silhouette area was relatively low (r2 < 0.9) but statistically significant. The correlation between shoot area and silhouette area were improved (r2 > 0.9) when shoot area was estimated from volume displacement or optical planimetry.
PROTON INDUCED X-RAY EMISSION ANALYSIS OF TRACE ELEMENTS IN THICK BREAD SAMPLES
Authors: AL-BEDRI MOHAMED BAKER , GHANI IKRAM JAMEEL ABDUL , AL-AGHIL IBRAHIM ABDUL RAHMAN
Published: January 2010

Proton induced X-ray emission (PIXE) technique has been used for identification and quantitative analysis of the elemental concentration in thick bread samples. Bread samples were air-oven dried at 60 oC and milled in a clean agate mortar to homogenize the sample and pressed into a pellet. PIXE technique relies on the analysis of the energy spectra of the characteristic X-ray emitted from the thick bread sample and the orchard leaf standard (NIST- SRM -1571) bombarded with 2.0 MeV protons. The concentration of the elements ( Cl , K , Ca , Mn , Fe , Cu , and Zn ) in the bread samples was determined by comparison with NIST orchard leaf standard. The accuracy of the measurements ranged between ± 2% and ± 10% for the most elements detected in this method. The aim of this study is to establish the reference concentration of trace elements in the Iraqi bread using PIXE technique.
ANALYSIS OF INDIAN SILVER COINS BY EDXRF TECHNIQUE
Authors: TRIPATHY B. B. , RAUTRAY T. R. , DAS SATYA R. , DAS MANAS R. , VIJAYAN V.
Published: January 2010

The analysis of some of the Indian silver coins during British rule were analysed by Energy Dispersive X-Ray Fluorescence Technique. Eight elements namely Cr , Fe , Ni , Cu , Zn , As , Ag and Pb were estimated in this study which also seems to indicate the fragmentation as well as the impoverishment of the power for the regimes that had produced the studied coins. While Cu and Ag were present as major elements, other elements were found to be present in minor concentration.
AN EOQ MODEL FOR ITEMS WITH A FIXED SHELF-LIFE AND A DECLINING DEMAND RATE BASED ON TIME-TO-EXPIRY TECHNICAL NOTE
Authors: AVINADAV TAL , ARPONEN TEIJO
Published: January 2010

This work presents an extension of the classical EOQ model for items with a fixed shelf life and a declining demand rate due to a reduction in the quality of the item in the course of its shelf-life. The demand rate, reflecting consumer preference for fresh items, is a polynomial function of the remaining time until the expiry date of the item. A mathematical model is developed to maximize the average profit per unit time, subject to shelf-life and marginal profit limitations. We prove that based on these limitations the model has a unique optimal solution and suggest a procedure for finding the optimal cycle length. A numeric example, including a sensitivity analysis, illustrates the model.
RELIABILITY EVALUATION OF LINEAR CONSECUTIVE-WEIGHTED-k-OUT-OF-n:F SYSTEM
Authors: ERYILMAZ SERKAN , TUTUNCU G. YAZGI
Published: January 2010

Reliability evaluation has a vital importance at all stages of processing and controlling modern engineering systems. In most of these modern systems the components have different contributions to the system, which are defined as weights. Among the other weighted systems, a linear consecutive-weighted-k-out-of-n:F system consists of n components, where each component has its own weight and reliability. The system fails if and only if the total weight of the failed consecutive components is at least k. The aim of this paper is to study the reliability of linear consecutive-weighted-k-out-of-n:F system consisting of independent & nonidentical and nonhomogeneous Markov dependent components. Exact formulae are provided for computing the reliability for above mentioned cases. Approximation formulae for the reliability are also presented.
A TEMPLATE-DRIVEN APPROACH FOR MAINTAINABLE SERVICE-ORIENTED INFORMATION SYSTEMS INTEGRATION
Authors: PAHL CLAUS , ZHU YAOLING , GACITUA-DECAR VERONICA
Published: January 2010

Service-oriented architecture (SOA) is currently the predominant software integration framework. Web services provide the predominant platform for SOA. SOA as an integration architecture solution supports a range of application scenarios. We present a solution for the integration of business information systems based on SOA and Web services. We discuss maintainability requirements in relation to information-specific integration and architecture aspects. A template-based approach based on modular and declarative transformation rules and architectural styles and patterns defines our solution to the maintainability problem of integration architectures.
INITIAL ROTATIONAL QUANTUM STATE EXCITATION AND ISOTOPIC EFFECTS FOR THE O(1D)+HCl → OH+Cl (OCl+H) REACTION
Authors: YANG HUAN , HAN KE-LI , NANBU SHINKOH , BALINT-KURTI GABRIEL G. , ZHANG HONG , SMITH SEAN C. , HANKEL MARLIES
Published: January 2010

We present reaction probabilities, branching ratios and vibrational product quantum state distributions for the reaction O (1D)+ HCl → OH+Cl (OCl+H) , Boltzmann averaged over initial rotational quantum states at a temperature of 300 K and also for the deuterium isotopic variant. The quantum scattering dynamics are performed using the potential energy surfaces for all three contributing electronic states. Comparisons are presented with results computed using only the ground electronic state potential energy surface, with results computed using only the j = 0 initial rotational state and also with results obtained using an equal weighting for the lowest 10 rotational states. Inclusion of the higher initial rotational states significantly changes the form of the reaction probability as a function of collision energy, reducing the threshold for reaction on the 1A" and 2A' excited electronic states. We found that the combined inclusion of higher initial rotational states and all three contributing electronic states is crucial for obtaining a branching ratio that is within the range and trend given by experiment from our J = 0 calculations. Isotopic effects range from tunnelling effects for the hydrogen variant and enhancement of reactivity for the production of OD on the excited electronic states.
STUDIES ON NUCLEOPHILIC SUBSTITUTION REACTIONS AT CARBON (SN2(C)) AND SILICON (SN2(Si)) IN TERMS OF AB INITIO, POTENTIAL, ACTING ON AN ELECTRON IN A MOLECULE AND MOLECULAR FACE THEORY
Authors: DING YAN-LI , GONG LI-DONG , ZHAO DONG-XIA , ZHANG MING-BO , YANG ZHONG-ZHI
Published: January 2010

The gas-phase identity bimolecular nucleophilic substitution reactions, Cl- + CH3 Cl → ClCH3 + Cl- and Cl- + SiH3Cl → ClSiH3 + Cl- , are investigated in terms of the ab initio method, potential acting on an electron in a molecule (PAEM) and molecular face (MF) theory. The computations have been performed at the CCSD(T)/aug-cc-pVTZ//MP2/6-311+G(3df,3pd) and CISD/aug-cc-pVDZ level. Based on the ab initio calculation, according to the PAEM theory, the strength of a chemical bond during forming or rupturing may be characterized by the D pb , which is a new physical quantity relating to the barrier height of the PAEM along a chemical bond. According to the MF theory, the interesting pictures of electron transfer and interpolarization effect between the reactants are clearly demonstrated to provide visualized spatial changing features of the MF for the title reactions along the IRC routes. The reason why [ Cl⋯CH3⋯Cl]- is a high-energy transition state is also analyzed in comparison with the stable low-energy intermediate [ Cl⋯SiH3⋯Cl]- .
INSIGHT INTO MECHANISM OF FORMATION OF C8 ADDUCTS IN CARCINOGENIC REACTIONS OF ARYLNITRENIUM IONS WITH PURINE NUCLEOSIDES II: AB INITIO, DFT, AND ABEEM/MM-MD SIMULATION STUDIES OF CHEMICAL REACTIONS CONCERNING N9-SUBSTITUTED PURINE BASES WITH 4-BIPHENYLYLNITRENIUM ION
Authors: QI SHI-FEI , WANG XIAO-NAN , YANG ZHONG-ZHI
Published: January 2010

Theoretical insight into the mechanism of C8 adducts formation in a series of complicated carcinogenic reactions has been provided in a previous work. However, two important issues involved in this mechanism still need to be elucidated in detail. Hence, in this paper, we first present a new theoretical model to study the direct formation mechanism of C8 adduct. It is found that this model can well reflect the actual interactions in the real carcinogenic reactions. Thus, a better theoretical model to simulate other properties of these complicated reactions is found using ab initio and density functional theory (DFT) methods. Second, we simulate the formation process of C8 adduct in this new theoretical model using ABEEM/MM-MD method. According to the MD study, we approve that the higher aqueous-phase activation energy for transition state in this kind of reaction contributes to weaker interactions between central sites of reaction and water compared with those for reactants. This study once more supports the mechanism of formation of C8 adducts in the actual carcinogenic reactions where arylnitrenium ions directly attack at C8 positions of nucleoside bases in DNA.
EXCITED-STATE INTRAMOLECULAR ELECTRON TRANSFER COUPLED WITH EXCITED-STATE INTRAMOLECULAR PROTON TRANSFER IN PHOTOINDUCED ENOL TO KETO TAUTOMERIZATION
Authors: LI YUANZUO , LIU SHASHA , ZHAO LILI , CHEN MAODU , MA FENGCAI , DING YONG
Published: January 2010

In this paper, the two-dimensional (2D) site and the three-dimensional (3D) cube representations [Sun MT, J Chem Phys124: 054903, 2006] have been further developed to study the charge transfer during excited-state relaxation. With these newly developed representations, we theoretically investigate the excited-state intramolecular electron transfer (ESIET) in enol excited-state geometry relaxation, and ESIET coupled with excited-state intramolecular proton transfer (ESIPT) in phototautomerization (in enol to keto transformation). The energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of HBODC in enol and keto absorption and fluorescence are compared to understand photoinduced ESIET and ESIPT process. The excited regions of molecule (where arrangement of electron density takes place during excited-state relaxation) are located with 2D site representation. 3D cube representations visualize the character of charge transfer (CT) in those regions. Results of the research indicate that the ability of charge transfer during enol excited-state geometry relaxation is much stronger than that in phototautomerization.
COMMUNITY ENTREPRENEURSHIP AMONG LOWER CASTES IN INDIA: A GRASSROOTS CONTRIBUTION TOWARDS POVERTY ALLEVIATION AND RURAL DEVELOPMENT UNDER CONDITIONS OF ADVERSITY AND ENVIRONMENTAL UNCERTAINTY
Authors: TORRI MARIA COSTANZA
Published: January 2010

This article has been retracted. Please contact jde@wspc.com
Regulation of gap junction coupling in bovine ciliary epithelium
Authors: Wang Zhao , Do Chi Wai , Valiunas Virginijus , Leung Chi Ting , Cheng Angela K. W. , Clark Abbott F. , Wax Martin B. , Chatterton Jon E. , Civan Mortimer M.
Published: January 2010

Aqueous humor is formed by fluid transfer from the ciliary stroma sequentially across the pigmented ciliary epithelial (PE) cells, gap junctions, and nonpigmented ciliary epithelial (NPE) cells. Which connexins (Cx) contribute to PE-NPE gap junctional formation appears species specific. We tested whether small interfering RNA (siRNA) against Cx43 (siCx43) affects bovine PE-NPE communication and whether cAMP affects communication. Native bovine ciliary epithelial cells were studied by dual-cell patch clamping, Lucifer Yellow (LY) transfer, quantitative polymerase chain reaction with reverse transcription (qRT-PCR), and Western immunoblot. qRT-PCR revealed at least 100-fold greater expression for Cx43 than Cx40. siCx43 knocked down target mRNA expression by 55 ± 7% after 24 h, compared with nontargeting control siRNA (NTC1) transfection. After 48 h, siCx43 reduced Cx43 protein expression and LY transfer. The ratio of fluorescence intensity (Rf) in recipient to donor cell was 0.47 ± 0.09 ( n = 11) 10 min after whole cell patch formation in couplets transfected with NTC1. siCx43 decreased Rf by ∼60% to 0.20 ± 0.07 ( n = 13, P < 0.02). Dibutyryl-cAMP (500 μM) also reduced LY dye transfer by ∼60%, reducing Rf from 0.41 ± 0.05 ( n = 15) to 0.17 ± 0.05 ( n = 20) after 10 min. Junctional currents were lowered by ∼50% ( n = 6) after 10-min perfusion with 500 μM dibutyryl-cAMP ( n = 6); thereafter, heptanol abolished the currents ( n = 5). Preincubation with the PKA inhibitor H-89 (2 μM) prevented cAMP-triggered current reduction ( n = 6). We conclude that 1) Cx43, but not Cx40, is a major functional component of bovine PE-NPE gap junctions; and 2) under certain conditions, cAMP may act through PKA to inhibit bovine PE-NPE gap junctional communication.
Autophagy in health and disease. 2. Regulation of lipid metabolism and storage by autophagy: pathophysiological implications
Authors: Czaja Mark J.
Published: January 2010

Autophagy is a lysosomal degradative pathway critical for the removal and breakdown of cellular components such as organelles and proteins. Despite striking similarities in the regulation and function of autophagy and lipid metabolism, the two processes have only recently been shown to be interrelated. This review details new findings of critical functions for autophagy in lipid metabolism and storage. Studies in hepatocytes and liver have demonstrated that macroautophagy mediates the breakdown of lipids stored in lipid droplets and that an inhibition of autophagy leads to the development of a fatty liver. In contrast, in adipocytes the loss of macroautophagy decreases the amount of lipid stored in adipose tissue through effects on white and brown adipocyte differentiation. Other investigations have indicated that the relationship between autophagy and lipids is bidirectional, with changes in cellular lipid content altering autophagic function. These newly described links between autophagy and lipid metabolism and storage have provided new insights into the mechanisms of both processes. The findings also suggest possible new therapeutic approaches to the problems of lipid overaccumulation and impaired autophagy that occur with aging and the metabolic syndrome.
Chronic intermittent hypobaric hypoxia decreases β-adrenoceptor activity in right ventricular papillary muscle
Authors: Guan Yue , Gao Lu , Ma Hui-Jie , Li Qian , Zhang Hao , Yuan Fang , Zhou Zhao-Nian , Zhang Yi
Published: January 2010

Chronic intermittent hypobaric hypoxia (CIHH) has an effective cardiac protection against ischemia-reperfusion injury. However, the underlying mechanisms are not fully known. It has been shown that blockade of β-adrenergic receptor exerts anti-arrhythmic action and improves cardiac remodeling in ischemic myocardium. Thus we determined the influence of CIHH on β-adrenergic receptor activity in right ventricular papillary muscle of rats. We found that the action potential duration in right ventricular papillary muscle was significantly longer in CIHH rats than in control rats. Activation of β-adrenergic receptor with dl-isoproterenol dose-dependently increased action potential duration and the contractility in right ventricular papillary muscle. In CIHH rats, the prolonged effect of dl-isoproterenol on action potential duration and the positive inotropic effect were significantly decreased compared with that in control rats. Furthermore, radioligand-binding experiments revealed that the density and affinity of β-adrenergic receptor in right ventricular myocardium was significantly lower in CIHH rats. In addition, Western blot analysis revealed that the membrane-bound G protein Gsα expression level in cardiac myocardium was significantly lower in CIHH rats than that in control rats. Collectively, these data suggest that CIHH suppresses β-adrenergic receptor action in right ventricular papillary muscle through decreasing receptor density and affinity, as well as membrane-bound Gsα. This mechanism may be involved in the cardiac protective effect of CIHH.
Alterations in molecular chaperones and eIF2α during lung endothelial cell apoptosis
Authors: Lu Qing , Jankowich Matthew , Newton Julie , Harrington Elizabeth O. , Rounds Sharon
Published: January 2010

We have previously demonstrated that inhibition of CAAX carboxyl methylation with AGGC caused redistribution and condensation of the ER molecular chaperones, glucose-regulated protein (GRP)-94 and calnexin; an effect that was attenuated by overexpression of dominant active RhoA. We have also shown that AGGC decreased GRP94 protein level; an effect that was dependent on caspase activity. In the present study, we tested the effects of inhibition of posttranslational processing of CAAX proteins on localization and protein levels of molecular chaperones and phosphorylation and protein level of eIF2α. We found that both AGGC, which inhibits CAAX carboxyl methylation, and simvastatin, which inhibits CAAX geranylgeranylation, caused relocalization of GRP94, calnexin, and calreticulin, effects that were not seen during endothelial apoptosis induced by TNF-α or ultraviolet (UV) irradiation. These results suggest that posttranslational processing of CAAX proteins is important in maintaining localization of molecular chaperones normally found in the ER. We also noted that AGGC, but not simvastatin, TNF-α, or UV irradiation, decreased protein levels of most molecular chaperones. Increased eIF2α phosphorylation was observed in the early stages of apoptosis, which was independent of the cause of apoptosis. These results suggest that eIF2α phosphorylation is a common early response to apoptosis-inducing stimuli. Interestingly, eIF2α protein level was decreased in the late stages of apoptosis induced by AGGC, TNF-α, and UV irradiation: an effect that was prevented by caspase inhibition. Thus we speculate that caspase(s)-dependent proteolysis of molecular chaperones and eIF2α may be novel signaling pathways of apoptosis. We also speculate that increased eIF2α phosphorylation is a defensive response against endothelial cell apoptosis.
Impairment of diaphragm muscle force and neuromuscular transmission after normothermic cardiopulmonary bypass: effect of low-dose inhaled CO
Authors: Ermilov Leonid G. , Pulido Juan N. , Atchison Fawn W. , Zhan Wen-Zhi , Ereth Mark H. , Sieck Gary C. , Mantilla Carlos B.
Published: January 2010

Cardiopulmonary bypass (CPB) is associated with significant postoperative morbidity, but its effects on the neuromuscular system are unclear. Recent studies indicate that even relatively short periods of mechanical ventilation result in significant neuromuscular effects. Carbon monoxide (CO) has gained recent attention as therapy to reduce the deleterious effects of CPB. We hypothesized that 1) CPB results in impaired neuromuscular transmission and reduced diaphragm force generation; and 2) CO treatment during CPB will mitigate these effects. In adult male Sprague-Dawley rats, diaphragm muscle-specific force and neuromuscular transmission properties were measured 90 min after weaning from normothermic CPB (1 h). During CPB, either low-dose inhaled CO (250 ppm) or air was administered. The short period of mechanical ventilation used in the present study (∼3 h) did not adversely affect diaphragm muscle contractile properties or neuromuscular transmission. CPB elicited a significant decrease in isometric diaphragm muscle-specific force compared with time-matched, mechanically ventilated rats (∼25% decline in both twitch and tetanic force). Diaphragm muscle fatigability to 40-Hz repetitive stimulation did not change significantly. Neuromuscular transmission failure during repetitive activation was 60 ± 2% in CPB animals compared with 76 ± 4% in mechanically ventilated rats ( P < 0.05). CO treatment during CPB abrogated the neuromuscular effects of CPB, such that diaphragm isometric twitch force and neuromuscular transmission were no longer significantly different from mechanically ventilated rats. Thus, CPB has important detrimental effects on diaphragm muscle contractility and neuromuscular transmission that are largely mitigated by CO treatment. Further studies are needed to ascertain the underlying mechanisms of CPB-induced neuromuscular dysfunction and to establish the potential role of CO therapy.
Quantitative analysis of aquaporin-2 phosphorylation
Authors: Xie Luke , Hoffert Jason D. , Chou Chung-Lin , Yu Ming-Jiun , Pisitkun Trairak , Knepper Mark A. , Fenton Robert A.
Published: January 2010

The action of vasopressin in rodent collecting ducts to regulate water permeability depends in part on increases in phosphorylation of the water channel aquaporin-2 (AQP2) at three sites: Ser256, Ser264, and Ser269. Previous studies of AQP2 phosphorylation have depended largely on qualitative data using protein mass spectrometry and phospho-specific antibodies. Here, we use a new method employing phospho-specific antibodies to determine the percentage of total AQP2 phosphorylated at each site in the presence and absence of the V2-receptor-selective vasopressin analog dDAVP in rat renal inner medullary collecting duct (IMCD) and cultured mpkCCD cells. Phosphorylation of Ser269, a site previously implicated in plasma membrane retention, was found to increase from 3 to 26% of total AQP2 in rat IMCD cells following dDAVP. Quantification of immunogold labeling of the opposite kidneys from the same rats estimated that 11% of total AQP2 is present in the apical plasma membrane (APM) without injection of dDAVP and 25% is present in the APM after dDAVP. Surprisingly, the baseline level of Ser256 phosphorylation was constitutively high, and there was no increase with dDAVP (confirmed in 2 more sets of rats). In general, Ser264 phosphorylation remained below 5% of total. The pattern of response was similar in cultured mpkCCD cells (large increase in Ser269 phosphorylation following dDAVP, but constitutively high levels of Ser256 phosphorylation). We suggest from these studies that Ser269 phosphorylation may be a more consistent indicator of vasopressin action and AQP2 membrane abundance than is Ser256 phosphorylation.
Mechanical properties of primary cilia regulate the response to fluid flow
Authors: Rydholm Susanna , Zwartz Gordon , Kowalewski Jacob M. , Kamali-Zare Padideh , Frisk Thomas , Brismar Hjalmar
Published: January 2010

The primary cilium is a ubiquitous organelle present on most mammalian cells. Malfunction of the organelle has been associated with various pathological disorders, many of which lead to cystic disorders in liver, pancreas, and kidney. Primary cilia have in kidney epithelial cells been observed to generate intracellular calcium in response to fluid flow, and disruption of proteins involved in this calcium signaling lead to autosomal dominant polycystic kidney disease, implying a direct connection between calcium signaling and cyst formation. It has also been shown that there is a significant lag between the onset of flow and initiation of the calcium signal. The present study focuses on the mechanics of cilium bending and the resulting calcium signal. Visualization of real-time cilium movements in response to different types of applied flow showed that the bending is fast compared with the initiation of calcium increase. Mathematical modeling of cilium and surrounding membrane was performed to deduce the relation between bending and membrane stress. The results showed a delay in stress buildup that was similar to the delay in calcium signal. Our results thus indicate that the delay in calcium response upon cilia bending is caused by mechanical properties of the cell membrane.
Mechanism of chronic aristolochic acid nephropathy: role of Smad3
Authors: Zhou Li , Fu Ping , Huang Xiao Ru , Liu Fei , Chung Arthur C. K. , Lai Kar Neng , Lan Hui Yao
Published: January 2010

Aristolochic acid nephropathy (AAN) has become a worldwide disease and is the most severe complication related to the use of traditional Chinese medicine. However, the pathogenic mechanisms of AAN remain unclear and therapies are limited. The present study tested the hypothesis that transforming growth factor (TGF)-β/Smad3 may be a key pathway leading to chronic AAN. This was examined in vivo in Smad3 wild-type/knockout (WT/KO) mice and in vitro in tubular epithelial cells with knockdown of Smad2 or Smad3. Results revealed that chronic administration of aristolochic acid (AA) resulted in a severe AAN characterized by progressive renal dysfunction and tubulointerstitial fibrosis including epithelial-mesenchymal transition (EMT) in Smad3 WT mice, but not in Smad3 KO mice, suggesting a critical role for Smad3 in the development of AAN. This was further tested in vitro. We found that AA was able to activate Smad signaling to mediate EMT and renal fibrosis via both TGF-β-dependent and JNK/MAP kinase-dependent mechanisms because blockade of JNK and specific knockdown of Smad3, but not Smad2, were able to attenuate AA-stimulated collagen matrix expression and EMT. In conclusion, TGF-β/Smad3 may be an essential mediator for chronic AAN. Results from this study indicate that specific blockade of the TGF-β/Smad3 signaling pathway may have therapeutic potential for chronic AAN.
Strength training versus aerobic interval training to modify risk factors of metabolic syndrome
Authors: Stensvold Dorth , Tjønna Arnt Erik , Skaug Eli-Anne , Aspenes Stian , Stølen Tomas , Wisløff Ulrik , Slørdahl Stig Arild
Published: January 2010

Metabolic syndrome is characterized by central obesity, elevated blood pressure, high fasting glucose and triglyceride levels, and low HDL levels. Regular physical activity can improve the metabolic profile and reduce the risks of cardiovascular diseases and premature mortality. However, the optimal training regime to treat metabolic syndrome and its associated cardiovascular abnormalities remains undefined. Forty-three participants with metabolic syndrome were randomized to one of the following groups: aerobic interval training (AIT; n = 11), strength training (ST; n = 11), a combination of AIT and ST (COM; n = 10) 3 times/wk for 12 wk, or control ( n = 11). Risk factors comprising metabolic syndrome were evaluated before and after the intervention. Waist circumference (in cm) was significantly reduced after AIT [95% confidence interval (CI): −2.5 to −0.04], COM (95% CI: −2.11 to −0.63), and ST (95% CI: −2.68 to −0.84), whereas the control group had an increase in waist circumference (95% CI: 0.37–2.9). The AIT and COM groups had 11% and 10% increases in peak O2 uptake, respectively. There were 45% and 31% increases in maximal strength after ST and COM, respectively. Endothelial function, measured as flow-mediated dilatation (in %), was improved after AIT (95% CI: 0.3–3), COM (95% CI: 0.3–3), and ST (95% CI: 1.5–4.5). There were no changes in body weight, fasting plasma glucose, or HDL levels within or between the groups. In conclusion, all three training regimes have beneficial effects on physiological abnormalities associated with metabolic syndrome.
In vivo measurement of proximal pulmonary artery elastic modulus in the neonatal calf model of pulmonary hypertension: development and ex vivo validation
Authors: Hunter Kendall S. , Albietz Joseph A. , Lee Po-Feng , Lanning Craig J. , Lammers Steven R. , Hofmeister Stephen H. , Kao Philip H. , Qi H. Jerry , Stenmark Kurt R. , Shandas Robin
Published: January 2010

Developing clinical work suggests that vascular stiffening plays a role in the progression of pulmonary hypertension (PH), while recent studies in animal models of hypoxic PH have found significant proximal vascular stiffening in the diseased population. Here, we develop and validate a minimally invasive, clinically realizable method to estimate the local elastic modulus of the proximal pulmonary arteries from pressure-diameter (PD) data. PD measurements were made in the main pulmonary arteries of 16 calves; lumen diameter was assessed using color M-mode tissue Doppler imaging ultrasound, while pressure was measured via catheter. Two methods corresponding to thin-walled pressure vessel theory (“thin”) and Lame's equation for a thick-walled cylinder (“thick”) were used to approximate the artery elastic modulus from PD measurements. The harvested arteries were tested independently to determine their “true” ex vivo elastic modulus and stiffness. Both approximations displayed excellent correlation with ex vivo elastic modulus of the calf main pulmonary artery (thin r2= 0.811; thick r2= 0.844; both P < 0.01). Bland-Altman analysis indicated that the thick-walled approximation has better overall agreement with ex vivo modulus. The approximations displayed quantitatively distinct regression slopes that were statistically different ( P = 0.02). The elastic modulus of the main pulmonary artery can be reasonably estimated from combined color M-mode tissue Doppler imaging ultrasound and catheter pressure measurements in calves. Such measurements may be a valuable tool in the diagnosis and treatment of human PH.
Effect of recovery duration from prior exhaustive exercise on the parameters of the power-duration relationship
Authors: Ferguson C. , Rossiter H. B. , Whipp B. J. , Cathcart A. J. , Murgatroyd S. R. , Ward S. A.
Published: January 2010

The physiological equivalents of the curvature constant (W′) of the high-intensity power-duration (P-tLIM) relationship are poorly understood, although they are presumed to reach maxima/minima at exhaustion. In an attempt to improve our understanding of the determinants of W′, we therefore aimed to determine its recovery kinetics following exhaustive exercise (which depletes W′) concomitantly with those of O2 uptake (V̇o2, a proxy for the kinetics of phosphocreatine replenishment) and blood lactate concentration ([L−]). Six men performed cycle-ergometer exercise to tLIM: a ramp and four constant-load tests, at different work rates, for estimation of lactate threshold, W′, critical power (CP), and maximum V̇o2. Three further exhausting tests were performed at different work rates, each preceded by an exhausting “conditioning” bout, with intervening recoveries of 2, 6, and 15 min. Neither prior exhaustion nor recovery duration altered V̇o2 or [L−] at tLIM. Postconditioning, the P-tLIM relationship remained well characterized by a hyperbola, with CP unchanged. However, W′ recovered to 37 ± 5, 65 ± 6, and 86 ± 4% of control following 2, 6, and 15 min of intervening recovery, respectively. The W′ recovery was curvilinear [interpolated half time ( t1/2) = 234 ± 32 s] and appreciably slower than V̇o2 recovery ( t1/2 = 74 ± 2 s) but faster than [L−] recovery ( t1/2 = 1,366 ± 799 s). This suggests that W′ determines supra-CP exercise tolerance, its restitution kinetics are not a unique function of phosphocreatine concentration or arterial [L−], and it is unlikely to simply reflect a finite energy store that becomes depleted at tLIM.
Reliability and Frequency Response of Excitatory Signals Transmitted to Different Types of Retinal Ganglion Cell
Authors: Freed Michael A. , Liang Zhiyin
Published: January 2010

The same visual stimulus evokes a different pattern of neural signals each time the stimulus is presented. Because this unreliability reduces visual performance, it is important to understand how it arises from neural circuitry. We asked whether different types of ganglion cell receive excitatory signals with different reliability and frequency content and, if so, how retinal circuitry contributes to these differences. If transmitter release is governed by Poisson statistics, the SNR of the postsynaptic currents (ratio of signal power to noise power) should grow linearly with quantal rate (qr), a prediction that we confirmed experimentally. Yet ganglion cells of the same type receive quanta at different rates. Thus to obtain a measure of reliability independent of quantal rate, we calculated the ratio SNR/qr, and found this measure to be type-specific. We also found type-specific differences in the frequency content of postsynaptic currents, although types whose dendrites branched at nearby levels of the inner plexiform layer (IPL) had similar frequency content. As a result, there was an orderly distribution of frequency response through the depth of the IPL, with alternating layers of broadband and high-pass signals. Different types of bipolar cell end at different depths of the IPL and provide excitatory synapses to ganglion cell dendrites there. Thus these findings indicate that a bipolar cell synapse conveys signals whose temporal message and reliability (SNR/qr) are determined by neuronal type. The final SNR of postsynaptic currents is set by the dendritic membrane area of a ganglion cell, which sets the numbers of bipolar cell synapses and thus the rate at which it receives quanta [SNR = qr × (SNR/qr)].
Processing of Horizontal Optic Flow in Three Visual Interneurons of theDrosophilaBrain
Authors: Schnell B. , Joesch M. , Forstner F. , Raghu S. V. , Otsuna H. , Ito K. , Borst A. , Reiff D. F.
Published: January 2010

Motion vision is essential for navigating through the environment. Due to its genetic amenability, the fruit fly Drosophila has been serving for a lengthy period as a model organism for studying optomotor behavior as elicited by large-field horizontal motion. However, the neurons underlying the control of this behavior have not been studied in Drosophila so far. Here we report the first whole cell recordings from three cells of the horizontal system (HSN, HSE, and HSS) in the lobula plate of Drosophila. All three HS cells are tuned to large-field horizontal motion in a direction-selective way; they become excited by front-to-back motion and inhibited by back-to-front motion in the ipsilateral field of view. The response properties of HS cells such as contrast and velocity dependence are in accordance with the correlation-type model of motion detection. Neurobiotin injection suggests extensive coupling among ipsilateral HS cells and additional coupling to tangential cells that have their dendrites in the contralateral hemisphere of the brain. This connectivity scheme accounts for the complex layout of their receptive fields and explains their sensitivity both to ipsilateral and to contralateral motion. Thus the main response properties of Drosophila HS cells are strikingly similar to the responses of their counterparts in the blowfly Calliphora, although we found substantial differences with respect to their dendritic structure and connectivity. This long-awaited functional characterization of HS cells in Drosophila provides the basis for the future dissection of optomotor behavior and the underlying neural circuitry by combining genetics, physiology, and behavior.