bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative stress and growth inhibition in the freshwater fish Carassius auratus induced by chronic exposure to sublethal fullerene aggregates
Authors: Zhu Xiaoshan , Zhu Lin , Lang Yupeng , Chen Yongsheng 
Published: April 2008

Abstract
The rapid growth of nanotechnology is stimulating research concerning the potential environmental impacts of manufactured nanomaterials. The present study summarizes, to our knowledge, the first examination regarding the potential effects of chronic exposure (32 d) of aquatic organisms (juvenile carp [Carassius auratus]) to sublethal concentrations (0.04–1.0 mg/L) of fullerene aggregates (nC60/aq; i.e., C60 suspended in water after long-term stirring) with average diameters of approximately 349 and/or 1,394 nm. The results demonstrated that the antioxidant enzymes superoxide dismutase and catalase were induced significantly in the gills and liver of C. auratus exposed to nC60/aq for 32 d, whereas a nonenzymatic antioxidant, glutathione, decreased in all tested tissues. In addition, lipid peroxidation (LPO) levels decreased in most cases, especially in the gills and brain, but exposure to 1.0 mg/L of nC60/aq led to a significant (p &lt; 0.01) increase in the LPO level in the liver. This increase in LPO level in combination with the observed oxidative stress suggested that the liver might be the target of or most susceptible organ to nC60/ aq exposure. Furthermore, the body weight and total length of juvenile carp exposed to 1.0 mg/L of nC60/aq for 32 d decreased significantly (p &lt; 0.05), indicating that nC60 /aq had an inhibitory effect on fish growth. The present findings imply that the oxidative stress induced by long-term exposure could be the main mechanism of the toxicity of nC60/aq to juvenile carp. This important work contributes to a better understanding of the potential health effects of exposure to manufactured nanomaterials on species in aquatic ecosystems.
Accuracy of chronic aquatic toxicity estimates determined from acute toxicity data and two time–response models
Authors: Barron Mace G , Raimondo Sandy , Russom Christine , Vivian Deborah N , Yee Susan H 
Published: April 2008

Abstract
Traditionally, chronic toxicity in aquatic organisms and wildlife has been determined from either toxicity test data, acute to chronic ratios, or application of safety factors. A more recent alternative approach has been to estimate chronic toxicity by modeling the time course of mortality as determined in standard acute toxicity tests, but these approaches have received limited validation. The accuracy of chronic toxicity estimates from two time–response models, linear regression analysis (LRA) and accelerated life testing (ALT), was investigated using a dataset of more than 150 matched species pairs of standard acute toxicity test data and measured chronic no-observed-effect concentrations (NOECs). Chronic survival was more accurately modeled by both ALT (accuracy, 69%) and LRA (accuracy, 76%) than was reproduction, growth, or the most sensitive endpoint (accuracy, 50–60%). In general, LRA estimates of chronic toxicity were less conservative than ALT estimates, with 66 to 79% of LRA estimates being greater than the measured NOEC. Acute datasets with early mortality produced estimates of chronic survival that were more accurate (ALT, 92%; LRA, 89%) compared to all datasets but were less conservative (84% of ALT estimates were overestimated vs 93% of LRA estimates). Acute datasets with late mortality resulted in poor ALT and LRA estimates of chronic toxicity for all endpoints. Additional survival time measurements did not improve the accuracy of ALT or LRA estimates of chronic toxicity over the standard four acute measurement times (24, 48, 72, and 96 h). The time course of mortality should be considered when applying time–response models to estimate chronic aquatic toxicity, with greater accuracy likely for chronic survival than for growth or reproduction.
Cenozoic gravity tectonics in the northern Gulf of Mexico induced by crustal extension. A new interpretation of multichannel seismic data
Authors: Rangin Claude , Le Pichon Xavier , Flotté Nicolas , Husson Laurent 
Published: April 2008

AbstractThe Gulf of Mexico margin in Texas is one of the most impressive examples of starved passive margin gravity collapse systems. Growth faults developed upslope and are compensated down slope by toe folding and thrusting. On the basis of new multi-channel seismic data with high penetration (down to 11 s-twtt) we present evidences for deep crustal extension and rifting that have enhanced superficial sliding. This hypothesis is supported by a significant heat flow anomaly and crustal thinning independently deduced from gravity data. This Cenozoic rifting episode is tectonically linked to left lateral motion along the Rio Bravo fault, a reactivated branch of the Texas lineament.
Thermal regime of the NW shelf of the Gulf of Mexico. Part A: Thermal and pressure fields
Authors: Husson Laurent , Henry Pierre , Le Pichon Xavier 
Published: April 2008

Abstract
The thermal field of the Gulf of Mexico (GoM) is analyzed from a comprehensive temperature-depth database of about 8500 bottom hole temperatures and reservoir temperatures. Our stochastic analysis reveals a widespread, systematic sharp thermal gradient increase between 2500 and 4000 m. The analysis of the pressure regime indicates a systematic correlation between the pressure and temperature fields.
Thermal regime of the NW shelf of the Gulf of Mexico Part B : Heat flow
Authors: Husson Laurent , Le Pichon Xavier , Henry Pierre , Flotte Nicolas , Rangin Claude 
Published: April 2008

Abstract
We restore the steady state heat flow of the NW shelf of the GoM by removing the transient effects of sedimentation, erosion and compaction. We estimate sedimentation and erosion rates for the NW margin of the GoM from stratigraphic data and vitrinite reflectance data, respectively, and show that they both affect significantly the thermal field. We perform a thermal modeling for 166 wells within the Texan shelf. We conclude that there is a general southeastward increase in the heat flow. This increase also correlates with major tectonic features of the NW shelf of the GoM. We propose that the main zones of extension, of fast recent sedimentation, and crustal thinning are due to geologically recent lithospheric thinning responsible for the higher heat flow.
The Rio Bravo fault, a major late Oligocene left-lateral shear zone
Authors: Flotte Nicolas , Martinez-Reyes Juventino , Rangin Claude , Le Pichon Xavier , Husson Laurent , Tardy Marc 
Published: April 2008

AbstractIt has generally been assumed that the last major compressive deformation in the Sierra Madre Oriental (Mexico) took place during the Laramide orogenesis (Upper Cretaceous – Early Eocene). We have studied the N120° Rio Bravo fault zone probably inherited from the Jurassic opening of the gulf of Mexico. This fault zone is located along the international boundary between United States and Mexico. We demonstrate that it was active mainly during the Oligocene. In the Ojinaga area (Chihuahua), the Sierra Madre Occidental, Oligocene volcanic sequences overlying conformably the sedimentary Upper Cretaceous sequence, are both tightly folded before 30 Ma. We think this folding is associated with motion of a major left-lateral fault, the Rio Bravo left lateral fault. These left-lateral fault system affects also the Sabinas fold-belt and extends below the Burgos bassin. This deformation is also imaged by gravimetric data and the offsets the Palaeocene-Eocene oil fields that are displaced left laterally. We propose that during the Oligocene, this ~1000 km long left-lateral shear zone that might be called the Rio Bravo fault was active during the Oligocene with a total offset of 40–60 km.
Hypoxia Increases Superoxide Anion Production from Bovine Coronary Microvessels, But Not Cardiac Myocytes, via Increased Xanthine Oxidase
Authors: KAMINSKI P. M. , WOLIN M. S. 
Published: April 2008

ABSTRACTObjective: To determine if 30 min of hypoxia (Po2 8–10 Torr) affects basal, mitochondrial, or xanthine oxidase‐derived lucigenin‐detectable superoxide anion (O2.‐) production by intact isolated bovine coronary microvessels and myocytes.Methods: O2.‐ was quantitated by lucigenin‐elicited chemiluminescence. Antimycin A (10 μM) and hypoxanthine (0.1 mM) were employed to increase O2.‐ from mitochondria and xanthine oxidase, respectively.Results: Chemiluminescence from microvessels and myocytes was enhanced (∼ twofold, P < 0.05, n = 8–10) by inhibition of Cu,Zn‐SOD via pretreatment with diethyldithiocarbamate (10 mM, 30 min) and was decreased (P < 0.05, n = 8–10) by an intracellular scavenger of O2.‐ (10 mM Tiron), but not by added SOD (3 μM, n = 8–10). In the presence of SOD inhibition, hypoxia produced a hypoxanthine‐dependent (n = 8–10) twofold increase in chemiluminescence (P < 0.05, n = 10) in microvessels but not in myocytes. Other combinations of hypoxia, antimycin, or hypoxanthine did not significantly alter chemiluminescence.Conclusions: Lucigenin appears to detect a basal intracellular source of O2.‐ in both microvessels and myocytes that is not derived from mitochondria or xanthine oxidase. Exposure to hypoxia does not appreciably increase basal O2.‐ in vessels or myocytes, but if exogenous hypoxanthine is supplied, microvessels show an increase in O2.‐ production presumably derived from xanthine oxidase.
Quantitative Laser Scanning Confocal Microscopy on Single Capillaries: Permeability Measurement
Authors: ADAMSON R. H. , LENZ J. F. , CURRY F. E. 
Published: April 2008

ABSTRACTObjective: We tested the hypothesis that there is significant solute loss to the superfusate during microvessel solute permeability measurement in frog mesentery which leads to underestimation of permeability coefficient. This is the first application of laser‐scanning confocal microscopy to measure microvessel permeability.Methods: Microvessel permeability to sodium fluorescein (0.5 mg/ml, MW 376) was measured in the presence of bovine serum albumin (10 mg/ml) in Ringer's solution. Every 11–12 s an optical section transverse to the vessel axis (x‐z section) was collected. The images were corrected for fluorescence attenuation in the z direction and nonuniformity of light collection (shading) in the x direction by comparison to a fluorescent standard. Extravascular fluorescence, which increased linearly with time, and the step increase in fluorescence intensity of the vessel lumen were used to calculate an apparent permeability. Measurements were made first with the tissue superfused with Ringer and second after changing the superfusate to mineral oil in order to retain solute potentially lost to Ringer superfusate.Results: The permeability to fluorescein measured with Ringer superfusate (5.0 ± SD 2.6 × 10−5 cm/s; n = 3) was not different from that measured with mineral oil covering the upper mesothelial surface (4.5 ± 1.9).Conclusions: Therefore, the loss of sodium fluorescein through the upper mesothelium does not significantly alter permeability under these conditions. These techniques enable detailed analysis of solute concentration gradients surrounding microvessels.
Specific 125I Neuropeptide Y Binding to Intact Cultured Bovine Adrenal Medulla Capillary Endothelial Cells
Authors: SANABRIA P. , SILVA W. I. 
Published: April 2008

ABSTRACTObjective: This study involved the pharmacological detection and characterization of binding sites for the neuromodulator neuropeptide Y (NPY) in an in vitro preparation of capillary endothelial cells derived from bovine adrenal medulla.Methods: Equilibrium binding assays were conducted on intact cells with 125I Bolton‐Hunter labeled NPY (125I‐BH‐NPY). The specificity of the high‐affinity binding site was evaluated in competition experiments with cold NPY, (Leu31, Pro34)NPY (a Y1 receptor ligand, Y1RL), NPY13–36 (a Y2 receptor ligand, Y2RL), and two other members of the pancreatic polypeptide‐fold (PP‐fold) family: peptide YY (PYY) and avian pancreatic polypeptide (APP). Forskolin‐stimulated adenylate cyclase activity was assessed to detect the participation of this second messenger pathway in the neuromodulator action at the studied cell preparation.Results: Nonlinear regression analysis of the binding data indicated the existence of high‐affinity binding sites with an equilibrium dissociation constant (Kd) value of 39.00 ± 12.84 nM and a maximal binding (Bmax) of 489.89 ± 155.49 fmol/106 cells (mean ± SE, n = 6). NPY, Y1RL, and PYY displayed a concentration that inhibits the specific binding by 50% IC50 (nM) values of 4.06 ± 1.66 (n = 4), 2.94 ± 0.75 (n = 5), and 18.36 ± 10.36 (n = 3), respectively. APP and Y2RL were unable to compete with 125I‐NPY in the concentration range 0.001–1 μM. Further evaluation of second messenger pathways suggested that NPY binding sites in this model are coupled to the inhibition of adenylate cyclase. NPY significantly inhibited the forskolin‐stimulated adenosine cyclic 3′,5′‐(hydrogen phosphate) (cAMP) accumulation with a maximal effect of 37.03 ± 6.28%, n = 5 and an IC50 of 5.96 ± 1.87 nM. The Y1RL produced a comparable response (IC50 = 5.35 ± 1.39 nM, n = 4; maximal inhibition of 61.05 ± 13.03%) and Y2LR had no detectable effect at a similar concentration range.Conclusions: The results demonstrate the existence of a Y1 receptor in the adrenal medulla capillary endothelial cells, which may be relevant to the postjunctional effect of NPY on this gland.
Mechanisms of Lactoferrin‐induced Leukocyte‐Endothelial Cell Adhesion in Postcapillary Venules
Authors: Asako Hiroshi , Kurose Iwao , Wolf Robert E. , Granger D. Neil 
Published: April 2008

ABSTRACT Objective: The objective is to determine the contributions of electrostatic charge, endothelial cell adhesion glycoproteins (P‐ and E‐selectins), and histamine to lactoferrin‐induced leukocyte adhesion in postcapillary venules. Methods: Rat mesentery was prepared for intravital microscopic observation. Erythrocyte velocity, vessel diameter, leukocyte rolling velocity, number of adherent and emigrated leukocytes, and velocity, flux, and number of rolling leukocytes were monitored in mesenteric venules (25–35 μm initial diameter). After control measurements were obtained for all parameters, lactoferrin, other cationic proteins (histone or α‐chymotrypsinogen A), or transferrin (an anionic iron‐binding protein) were infused into the superior mesenteric artery, with repeat measurements taken 20 min into the infusion period. In other lactoferrin experiments, animals were treated with either a monoclonal antibody (MAb) directed against P‐ or E‐selectin, an H1‐ or H2‐histamine receptor antagonist, or diamine oxidase (histaminase). Results: Increased numbers of rolling and adherent leukocytes were observed during infusion of lactoferrin, histone, or α‐chymotrypsinogen A but not with transferrin. The leukocyte‐endothelial cell adhesion (LECA) elicited by lactoferrin was substantially greater than that induced by histone and α‐chymotrypsinogen A. The P‐selectin MAb completely prevented lactoferrin‐induced LECA, whereas the E‐selectin MAb had no effect. Diamine oxidase and the H1− (but not the H2−) receptor antagonist were also effective in attenuating lactoferrin‐induced LECA. Conclusions: These results indicate that lactoferrin‐induced LECA results from histamine‐mediated expression of P‐selectin on venular endothelial cells. The cationic nature of lactoferrin accounts for only a small part of its proadhesive actions.
Upregulation of Na+‐dependent Alanine Transport in Vascular Endothelial Cells by Serum: Role of Intracellular Ca2+
Authors: Escobales Nelson , Martinez Jose , Gonzalez Orlando 
Published: April 2008

ABSTRACT Objective: Amino acid transport and its regulation in vascular endothelial cells remains a largely unexplored area. In this study, we evaluated alanine transport in bovine aortic endothelial cells to assess possible mechanisms of regulation. Methods: Alanine transport into confluent monolayers of endothelial cells was measured using 100 μM [3H]alanine in the presence and absence of external Na+, in cells deprived of serum for 24 hr (SD), and in SD cells exposed to 10% serum (S) for 3 hr (SD + S cells). Results: Our results indicate that although SD did not significantly affect the Na+‐independent transport of alanine when compared to normal cells, serum addition to serum‐deprived cells markedly stimulated the Na+‐dependent uptake of this amino acid through system A. The stimulation of alanine transport pathway(s) by serum was totally abolished by pretreatment of endothelial cells with 10 μM. cycloheximide, suggesting a role of protein synthesis. Serum also induced a marked increase in calcium recycling at the cell membrane, suggesting that calcium is a key element of the serum signaling pathway. Indeed, both BAPTA (20 μM), a cellular calcium chelator, and thapsigargin (1 μM), an agent that depletes intracellular calcium stores, prevented the stimulation of alanine uptake by serum. Finally, pertussis toxin (400 ng/ml), an agent known to inactivate certain G‐protein‐dependent pathways, significantly reduced the serum‐dependent 45Ca uptake and [3H]alanine entry. However, the protein kinase C activator PMA (100 nM), significantly reduced the stimulation of alanine uptake by serum but did not affect the stimulation of calcium uptake. Conclusions: Altogether these findings suggest that cell calcium is involved in the regulation of system A by serum in vascular endothelial cells.
Fiber Matrix Descriptors from Permeability Data Without Requiring Membrane Thickness: Theory, Results, and Optimization
Authors: Katz Murray A. , Lamarche Margaret 
Published: April 2008

ABSTRACTObjective: Permeability of basement membrane and all other barriers contains a term for membrane thickness (Δx). This naturally leads to development of methods for measuring Δx that are imprecise, inaccurate, expensive, subject to preparation artifact, and inattentive to variability. Although height and shape of permeability (P) vs. probe radius (α) curves are sensitive to Δx, ln(P) or ln(P/free diffusivity or Do) curves have shapes independent of Δx. It should, thus, be possible using such characteristics to determine fiber radius (rf) and void volume ratio (ε) without Δx. We developed such a method to derive membrane structure by the standard model of Ogston and present its experimental evaluation.Methods: Basement membranes were self‐assembled using 1: 1 Matrigel: 0.01 M Tris/150 mM NaCl/1.0 mM CaCl2 buffer on 0.4‐μ polycarbonate supports with transport measured in diffusion chambers using FITC‐labeled hydroxyethyl starch probes from 25 to 102 Å in radius. Sampling was at 0.5 hr and then for each hour up to 5. Other membranes were measured 7 days after formation.Results: The best fit of the new technique occurred at 3 hr with R2 = 0.949 ± 0.003 SEM, rf = 36.8 ± 2.4 Å, and ε = 0.87 ± 0.02. Membranes studied for 7 days showed more variability but essentially the same characteristics.Conclusions: Membrane thickness is not necessary to reduce permeability of basement membrane to structure, and optimum sampling time is 3 hr.
Transglomerular Transport of DEAE Dextran in the Isolated Perfused Kidney
Authors: Adal Yalçin , Pratt Lynette , Comper Wayne D. 
Published: April 2008

ABSTRACTObjective: The renal fractional clearance of [3H]DEAE dextran has been widely used to substantiate the charge selective model for renal permselectively, although there has only been one reported study on this type of clearance. This study sets out to examine the fractional clearance and glomerular processing of DEAE dextran.Methods: Fractional clearance studies were performed using isolated perfused rat kidneys. The glomerular processing of DEAE dextran was assessed by examining the kinetics of DEAE dextran uptake in glomerluli isolated post perfusion.Results: The fractional clearance of DEAE dextran used in the concentration range of 15–150 μg/ml in the perfusate of the isolated perfused kidney did not produce the classical in vivo facilitated transport of DEAE dextran as compared to dextran as observed by Bohrer et al. The fractional clearance curve displays retarded clearance of low molecular weight (small radii) DEAE dextran, giving the appearance of a ‘flat curve’. Similar results were obtained when an oxygen free radical scavenger cocktail was included in the perfusate. These results may be due to the fact that DEAE dextran binds to the glomeruli (at an order of magnitude greater than dextran sulfate). Perfused kidneys with [3H]DEAE dextran for 1 h followed by a five minute perfusion with unlabelled DEAE dextran revealed no significant change in the glomerular levels of [3H]DEAE dextran (unlike dextran sulfate). Perfusion of rat kidneys with 15 μg/ml DEAE dextran produced no changes in the electron microscopical morphology of the glomerulus and no changes in the fractional clearance of dextran.Conclusions: These results do not support the glomerular charge selectivity model that involves a non‐binding electrostatic interaction of the charged dextran with the fixed anion charges of the glomerular capillary wall.
Regional Changes in Capillary Supply in Skeletal Muscle of Interval‐Sprint and Low‐Intensity, Endurance‐Trained Rats
Authors: Gute Dean , Laughlin M. Harold , Amann John F. 
Published: April 2008

ABSTRACTObjective: Exercise training produces regional increases in blood flow capacity among muscle fibers that experience increased activity during exercise. We tested the hypothesis that this increase is partially due to capillary angiogenesis among muscle fibers with large increases in activity during exercise training bouts.Methods: Two training programs were evaluated: a program consisting of 10–12 weeks of exposure to low‐intensity (30 m/min, 0 incline, 60 min/day) (LET) exercise bouts, 5 days/week, and a second program consisting of 8–10 weeks of exposure to repetitive bouts (6/day) of sprint (60 m/min, 15% incline) exercise, alternating running (2.5 min) and recovery (4.5 min), 5 days/week (IST). Cage‐confined rats were utilized (SED) as controls. After training was completed, rat hindquarters were perfusion‐fixed with modified Karnovsky's fixative. Transverse sections from soleus (Sol), and red (GR), mixed (GM), and white (GW) portions of gastrocnemius muscle were prepared to evaluate capillarization. Sections were analyzed using the Olympus Cue 2 Image Analyzer to determine capillary/muscle fiber ratio (C/F), number of capillary profiles per square millimeter of muscle area (CND), capillary surface area per volume of tissue, and capillary volume density.Results: Average area per muscle fiber and sarcomere length did not differ among groups. LET did not affect capillarization of the GW, whereas increasing C/F in GM (2.3 ± 0.1 versus 2.1 ± 0.1 for SED) and GR (3.0 ± 0.1 versus 2.6 ± 0.1 for SED). IST increased C/F and CND in GW (1.6 ± 0.1 versus 1.3 ± 0.0 for SED and 657 ± 74 versus 418 ± 53 for SED, respectively) and increased C/F ratio in GM (2.3 ± 0.1 versus 2.1 ± 0.1 for SED). IST did not increase capillarization of the GR. The capillarization of the soleus muscle was not affected by either exercise training program.Conclusions: IST increased capillarization in muscle tissue composed of a high percentage of fast glycolytic fibers (GW and GM) and LET increased capillarization of muscle tissue composed of a high percentage of fast oxidative‐glycolytic fibers (GM and GR).