bluuebunny/crossref_metadata_2025 huggingface dataset:
Fish community change in Lake Superior, 1970–2000
Authors: Bronte Charles R , Ebener Mark P , Schreiner Donald R , DeVault David S , Petzold Michael M , Jensen Douglas A , Richards Carl , Lozano Steven J
Published: January 2004

Changes in Lake Superior's fish community are reviewed from 1970 to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) stocks have increased substantially and may be approaching ancestral states. Lake herring (Coregonus artedi) have also recovered, but under sporadic recruitment. Contaminant levels have declined and are in equilibrium with inputs, but toxaphene levels are higher than in all other Great Lakes. Sea lamprey (Petromyzon marinus) control, harvest limits, and stocking fostered recoveries of lake trout and allowed establishment of small nonnative salmonine populations. Natural reproduction supports most salmonine populations, therefore further stocking is not required. Nonnative salmonines will likely remain minor components of the fish community. Forage biomass has shifted from exotic rainbow smelt (Osmerus mordax) to native species, and high predation may prevent their recovery. Introductions of exotics have increased and threaten the recovering fish community. Agencies have little influence on the abundance of forage fish or the major predator, siscowet lake trout, and must now focus on habitat protection and enhancement in nearshore areas and prevent additional species introductions to further restoration. Persistence of Lake Superior's native deepwater species is in contrast to other Great Lakes where restoration will be difficult in the absence of these ecologically important fishes.
Fish as potential dispersal agents for floodplain plants: first evidence in North America
Authors: Chick John H , Cosgriff Robert J , Gittinger Lori S
Published: January 2004

In river–floodplain ecosystems with seasonal flood pulses, many species display adaptations to take advantage of resources in the aquatic–terrestrial transition zone. Frugivory and seed dispersal by fishes is a clear example of such adaptations, known primarily from South American river–floodplain systems. Here, we document consumption of red mulberry (Morus rubra) and swamp privet (Forestiera acuminata) fruit by channel catfish (Ictalurus punctatus) in the floodplain of the Mississippi River, U.S.A., and demonstrate that red mulberry and swamp privet seeds will germinate after being consumed by channel catfish. In a common-garden experiment, consumption of fruits and seeds by channel catfish improved germination success of these riparian plants relative to a treatment simulating fruit dropped during a flood without being consumed by fish. This is the first study to provide evidence of frugivory and viability of seeds ingested by fish in a North American river–floodplain ecosystem. Frugivory and seed dispersal by fishes may be more widespread than previously thought.
Assessment of streetcar transit priority options using microsimulation modelling
Authors: Shalaby Amer , Abdulhai Baher , Lee Jinwoo
Published: January 2004

The thrust of a recently published transportation vision for Toronto is focused largely on reducing automobile dependence via a number of interacting strategies, including the wide application of transit priority policies to improve transit competitiveness. This paper reports on quantifying the impacts of several transit priority schemes, with the streetcar operation along King Street in the heart of Toronto as a case study. Four scenarios were modelled in a micro simulation framework. They include the status quo (involving unconditional transit signal priority, already in operation), turning off existing transit signal priority, prohibiting all left turns, and finally prohibiting traffic from King Street. To quantify the impacts of any of the above scenarios, a set of common measures of effectiveness was used, including transit travel time and speed, effective headway, service frequency and person throughput, bunching, fleet size implications, and overall traffic and transit average speeds. The results show the relative merits of the four scenarios and two strategies for improving streetcar service along the King route are recommended. The first is to prohibit all left turns along the route, while the second, admittedly more aggressive, is to potentially transform the arterial into a transit mall accessible only to streetcars.Key words: transit signal priority, transit priority, signal control, microsimulation, streetcars.
Reinforcement learning: Introduction to theory and potential for transport applications
Authors: Abdulhai Baher , Kattan Lina
Published: January 2004

The aim of this paper is to develop insight into the potential of reinforcement learning (RL) agents and distributed reinforcement learning agents in the domain of transportation and traffic engineering and specifically in Intelligent Transport Systems (ITS). This paper provides a crystallized, comprehensive overview of the concept of RL and presents related successful applications in the field of traffic control and transportation engineering. It is divided into two parts: the first part provides a thorough overview of RL and its related methods and the second part reviews most recent applications of RL algorithms to the field of transportation engineering. Finally, it identifies many open research subjects in transportation in which the use of RL seems to be promising.Key words: reinforcement learning, machine learning, traffic control, artificial intelligence, intelligent transportation systems.
Comparison of MOBILE5a, MOBILE6, VT-MICRO, and CMEM models for estimating hot-stabilized light-duty gasoline vehicle emissions
Authors: Rakha Hesham , Ahn Kyoungho , Trani Antonio
Published: January 2004

The paper compares the MOBILE5a, MOBILE6, Virginia Tech microscopic energy and emission model (VT-Micro), and comprehensive modal emissions model (CMEM) models for estimating hot-stabilized, light-duty vehicle emissions. Specifically, Oak Ridge National Laboratory (ORNL) and Environmental Protection Agency (EPA) laboratory fuel consumption and emission databases are used for model comparisons. The comparisons demonstrate that CMEM exhibits some abnormal behaviors when compared with the ORNL data, EPA data, and the VT-Micro model estimates. Specifically, carbon monoxide (CO) emissions exhibit abrupt changes at low speeds and high acceleration levels and constant emissions at negative acceleration levels. Furthermore, oxides of nitrogen (NOx) emissions exhibit abrupt drops at high engine loads. In addition, the study demonstrates that MOBILE5a emission estimates compare poorly with EPA field data, while MOBILE6 model estimates show consistency with EPA field data and VT-Micro model estimates over various driving cycles. The VT-Micro model appears to be accurate in estimating hot-stabilized, light-duty, normal vehicle tailpipe emissions. Specifically, the emission estimates of the VT-Micro and MOBILE6 models are consistent in trends with laboratory measurements. Furthermore, the VT-Micro and MOBILE6 models accurately capture emission increases for aggressive acceleration drive cycles in comparison with other drive cycles.Key words: transportation energy, transportation environmental impacts, VT-Micro Model, CMEM, MOBILE5, MOBILE6, fuel consumption models, emission models.
Design radius requirements for simple horizontal curves on three-dimensional alignments
Authors: Easa Said M , Dabbour Essam
Published: January 2004

Current North American design guides have established mathematical relationships to calculate the minimum radius required for horizontal curves as a function of design speed, maximum superelevation, and maximum side friction. For three-dimensional (3-D) alignments, the design guides consider the alignment as two separate horizontal and vertical alignments and consequently ignore the effect of vertical alignment. This paper evaluates the effect of vertical alignment on minimum radius requirements using computer simulation, with a focus on trucks. For 3-D alignments, the results showed that existing design guidelines for minimum radius need to be increased by as much as 20% to achieve the same comfort limit on flat horizontal curves. It is interesting to note that in some cases truck rollover occurred before the side-friction comfort level is reached. This indicates the need for developing a different design control for trucks on 3-D alignments than the comfort criterion used for passenger cars on flat horizontal curves. Based on the simulation results, mathematical models for design radius requirements for passenger cars and trucks were developed.Key words: geometric design, horizontal curve radius, three-dimensional alignments, vehicle stability.
Traffic and speed characteristics on two-lane highways: field study
Authors: Hassan Yasser
Published: January 2004

Many models have been developed to evaluate the operating speeds on two-lane rural highways. However, provided information usually lacks details essential to assess their applicability at locations other than where they were developed. This paper presents a procedure to interpret raw data collected on three horizontal curve sites of different two-lane rural highway classes in Ontario. The speed observations were categorized into three vehicle classes (passenger car, light truck, and multi-axle heavy truck) and four light condition categories (day, night, and two transition periods). The minimum headway and percentile value to define the operating speed were examined, and a revision of the current practice deemed not warranted. The findings also indicated that operating speeds do not depend on the time or vehicle class. Finally, the horizontal alignment affects the operating speed, but the speeds of the two travel directions on a horizontal curve may differ even with little contribution of the vertical alignment.Key words: highway geometric design, operating speed, traffic composition, traffic counters, ambient light, acceleration, deceleration.
Proactive freeway crash prevention using real-time traffic control
Authors: Lee Chris , Hellinga Bruce , Saccomanno Frank
Published: January 2004

This paper makes use of a probabilistic model that predicts the likelihood of crashes (crash potential) on freeways on the basis of traffic flow conditions, in real-time crash prevention. The model was developed using incident logs and loop detector data collected over a 13-month period on the Gardiner Expressway in Toronto. Previous work suggested that an increase in levels of traffic turbulence generally yields high crash potential. Traffic turbulence was defined in terms of a series of crash precursors that represent traffic conditions that were present prior to crash occurrence. To apply the model in crash prevention, the link needs to be established between crash potential and real-time safety intervention. The objective of this paper is to explore this link for different thresholds of crash potential. The paper discusses the guidelines for evaluating the safety benefit of one crash prevention strategy (variable speed limits) and suggests the risk-based evaluation framework for real-time traffic control.Key words: crash, accident, freeway, safety, traffic flow, real-time control.
Identifying urban boundaries: application of remote sensing and geographic information system technologies
Authors: Abed Jamal , Kaysi Isam
Published: January 2004

This paper focuses on a new definition of urbanization trends by investigating the concept of a fuzzy urban boundary (UB) that assigns different membership levels to urbanized aggregates based on a proposed composite index. The research work builds on this logic to investigate a new approach in defining urbanized areas by compounding the characteristics of the fuzzy density of an urban agglomeration with land use variation and intensity of economic activity. Spatial overlaying capabilities of geographic information system (GIS) are used to model the urbanization trend in the case study of Greater Beirut. The UB is defined using a multispectral high resolution visible (HRV) Satellite Pour L'observation de la Terre (SPOT) satellite image. The challenges of urban modelling using satellite images are addressed through an investigative approach in cartographic feature extraction and delineation of the urban agglomeration. This entails image treatment of the spot HRV image, defining internal characteristics of the urban agglomeration and constructing spatially continuous socio-economic data sets that can be combined with the digital remotely sensed image.Key words: fuzzy logic, GIS, remote sensing, spatial urban modelling, urban boundary, urbanization trends.
The effect of construction designs on temperature field of a roller compacted concrete dam — a simulation analysis by a finite element method
Authors: Chen Y L , Wang C J , Li S Y , Chen L J
Published: January 2004

In this paper a numerical simulation of the construction process of roller compacted concrete (RCC) dams is presented. The following features of construction of mass concrete have been considered: hydration heat, age, placing temperature, starting placement date, and placing speed. A 3-D finite element model of the Long-Tan RCC dam, which is to be built in the Guangxi Autonomous Region in China, was analyzed. Temperature distribution and evolution inside the RCC dam were calculated during and after the completion of the dam. Using FortranTM code, a 3-D thermal simulation analysis of a high RCC dam can be realized on a computer at the construction site. Based on the real factors during the construction period, engineers can predict the distribution of temperature in the RCC dam. Therefore, engineers can take appropriate measures to control concrete temperature to reduce thermal stress within the dam. The effects of the concrete placing temperature, construction speed, and starting date on the temperature are discussed. It has been found that the maximum temperature in a dam can be reduced by 20% through temperature control measures.Key words: RCC dam, thermal simulation analysis, finite element method, temperature field, construction schedule.
Influence of high salinities on the degradation of diesel fuel by bacterial consortia
Authors: Riis Volker , Kleinsteuber Sabine , Babel Wolfgang
Published: January 2004

Microbial communities from three Argentinean saline soils were extracted and tested for their ability to degrade diesel fuel in liquid culture at salinities between 0% and 25%. In each case, the degradation process was continuously monitored by measuring oxygen consumption. Two communities (CR1 and CR2) showed nearly equal degrees of degradation across a salinity range of 0%–10% (the former degrading about 63% of the diesel fuel and the latter about 70% after 53 and 80 d, respectively). Furthermore, the degree of degradation was not significantly lower in the presence of 17.5% salt (58% and 65% degraded, respectively). A third community (El Zorro) showed a maximum turnover at 5% salt (79% diesel fuel degraded) and significant degradation (66%) at a salinity of 10%. However, the degree of degradation by this community clearly dropped at 0% and 15% salt. None of the communities were able to degrade diesel fuel in the presence of 25% salt, but the living cell counts showed that components of the microbial population survived the long-term exposure. The surviving portion is obviously sufficient to allow substantial restoration of the original community, as verified by the BIOLOG method. Isolates of the CR1 community were identified as members of the genera Cellulomonas, Bacillus, Dietzia, and Halomonas. In light of our investigations, the bioremediation of contaminated saline soils should be quite possible if the salinity of the soil water is lower than 15% or if it is reduced below this limit by the addition of water.Key words: salinity, diesel fuel, degradation, halotolerant and halophilic microorganisms, soil communities, diversity.
FeoB is not required for ferrous iron uptake inCampylobacter jejuni
Authors: Raphael Brian H , Joens Lynn A
Published: January 2004

Among strains of Campylobacter jejuni, levels of ferrous iron (Fe2+) uptake was comparable. However, C. jejuni showed a lower level of ferrous iron uptake than Escherichia coli. Consistent with studies of E. coli, Fe2+uptake in C. jejuni was significantly enhanced by low Mg2+concentration. The C. jejuni genome sequence contains a single known ferrous iron uptake gene, feoB, whose product shares 50% amino acid identity to Helicobacter pylori FeoB and 29% identity to E. coli FeoB. However, Fe2+uptake could not be attributed to FeoB for several reasons. Site-directed mutations in feoB caused no defect in55Fe2+uptake. Among C. jejuni strains, various nucleotide alterations were found in feoB, indicating that some C. jejuni feoB genes are defective. In addition, uptake could not be attributed to the magnesium transporter CorA, since no reduction in55Fe2+uptake was observed in the presence of a CorA-specific inhibitor.Key words: Campylobacter jejuni, ferrous iron uptake, metal transport, FeoB.
Manganese–lignin peroxidase hybrid fromBjerkandera adustaoxidizes polycyclic aromatic hydrocarbons more actively in the absence of manganese
Authors: Wang Yuxin , Vazquez-Duhalt Rafael , Pickard Michael A
Published: January 2004

We studied polycyclic aromatic hydrocarbon (PAH) oxidation using whole cells and purified manganese-lignin peroxidase (MnLiP) from Bjerkandera adusta UAMH 8258. Although the metabolism of PAHs by B. adusta has been previously demonstrated, less than 5% mineralization of14C-labelled PAHs occurred in this study over a 40-day period. Oxidation of PAHs was examined by a purified MnLiP hybrid isoenzyme in the presence and absence of manganous ions. The rate of PAH oxidation was decreased by the presence of Mn. The substrates were anthracene and its methyl derivatives, pyrene and benzo[a]pyrene, PAHs with ionization potentials of 7.43 eV or lower. The PAH metabolites of the Mn-independent reaction were identified as the corresponding quinones. The pH optimum of the Mn-independent oxidation was generally about 4, while for the Mn-dependent reaction it was 3. The kinetic constants for the Mn-independent oxidation of 2-methylanthracene at pH 4 were determined, and the values we obtained were a kcatof 145/min, KM,appof 23.8 mmol/L for the aromatic substrate, and KM,appof 0.2 mmol/L for hydrogen peroxide. This is the first report of PAH oxidation by a MnLiP hybrid isoenzyme from white rot fungi.Key words: manganese peroxidase, polycyclic aromatics, oxidation, Bjerkandera adusta.
Chronic glucose-lowering effects of rosiglitazone and bis(ethylmaltolato)oxovanadium(IV) in ZDF rats
Authors: Yuen Violet G , Bhanot Sanjay , Battell Mary L , Orvig Chris , McNeill John H
Published: January 2004

The aim of this study was to determine if there was a synergistic or additive effect of a thiazolidinedione derivative (rosiglitazone (ROS)) and a vanadium compound (bis(ethylmaltolato)oxovanadium(IV) (BEOV)) on plasma glucose and insulin levels following chronic oral administration to Zucker diabetic fatty (ZDF) rats. Whole-blood vanadium levels were determined at time 0 and at days 1, 6, and 18. The doses of BEOV (0.1 mmol/kg) and ROS (2.8 µmol/kg) were selected to produce a glucose-lowering effect in 30% (ED30) of animals. Both drugs were administered daily by oral gavage as suspensions in 1% carboxymethylcellulose (CMC) in a volume of 2.5 mL/kg. The total volume administered to all rats was 5 mL/(kg·day). The combination of BEOV and ROS was effective in lowering plasma glucose levels to <9 mmol/L in 60% of fatty animals as compared with 30% for BEOV and 10% for ROS alone. The age-dependent decrease in plasma insulin levels associated with β-cell failure in the ZDF rats did not occur in the BEOV-treated fatty groups. There was no effect of any treatment on body weight; however, there was a significant reduction in both food and fluid intake in fatty groups treated with BEOV. There were no overt signs of toxicity and no mortality in this study. Both BEOV and ROS were effective in lowering plasma glucose levels, as stated above, and there was at least an additive effect when BEOV and ROS were used in combination.Key words: rosigitazone, bis(ethylmaltolato)oxovanadium(IV), diabetes, ZDF rats.
Cellular and humoral responses to collagenpolyvinylpyrrolidone administered during short and long periods in humans
Authors: Furuzawa-Carballeda Janette , Rojas Emilio , Valverde Mahara , Castillo Irma , de León Lino Diaz , Krötzsch Edgar
Published: January 2004

Collagen, particularly type I, and its related derivatives have been extensively employed in many areas of pharmacology. The present study was performed to determine the safety of collagenpolyvinylpyrrolidone (collagenPVP) by in vitro and in vivo studies. Sera and peripheral blood cells from healthy donors without treatment and patients treated with collagenPVP were evaluated. We observed that the biodrug does not stimulate lymphoproliferation or DNA damage in vitro, nor does it induce human anti-porcine type I collagen or anti-collagenPVP antibodies in vivo. Furthermore, no hepatic or renal metabolic dysfunctions were observed when collagenPVP was administered by intradermal or intramuscular routes in short- or long-term treatments. In conclusion, the present work shows that no cellular damage or immunological adverse effects (cellular and humoral) occurred during collagenPVP treatment, even after more than 400 weeks of consecutive administrations.Key words: collagenpolyvinylpyrrolidone, DNA damage, collagen antibodies, hypertrophic scar.
Effects of statins on myocardial and coronary artery response to ischemia-reperfusion
Authors: Rendig Stephen V , Symons J David , Amsterdam Ezra A
Published: January 2004

This study tested the hypotheses that (i) lipophilic statins (atorvastatin and simvastatin) impair ventricular recovery from myocardial ischemia–reperfusion, owing to their greater myocyte permeability, compared with a hydrophilic statin (pravastatin), and (ii) statins enhance endothelium-dependent vasodilation of isolated coronary arteries from the ischemic region. Farm pigs consumed chow supplemented with atorvastatin (2.5 mg·kg–1·d–1; n = 6), pravastatin (10 (n = 3) or 20 (n = 2) mg·kg–1·d–1), simvastatin (5 mg·kg–1·d–1; n = 6), or no statin (control; n = 6) for 3 weeks. Animals were anesthetized and instrumented to measure regional (% segment shortening) and global (dP/dt max) left ventricular (LV) function during coronary artery occlusion (10 min) and reperfusion (30 min). Coronary resistance (i.d. = 119 ± 3 µm) and conductance (i.d. = 487 ± 11 µm) arteries were isolated from the ischemic region to measure receptor-dependent (acetylcholine (ACh)) and -independent (KCl) vasoconstriction, and endothelium-dependent (bradykinin (BK)) and -independent (sodium nitroprusside (SNP)) vasodilation. At 30 min reperfusion, neither percent recovery of regional ventricular function (atorvastatin, 24% ± 15%; pravastatin, 36% ± 13%; simvastatin, 29% ± 13%; control, 36% ± 13%) nor percent recovery of global LV cardiac function differed among groups. However, BK-induced vasorelaxation of coronary conductance vessels was greater (P < 0.05) in statins versus controls, and ACh-induced vasoconstriction was less in simvastatin-treated animals, suggesting the potential for enhanced coronary arterial blood flow to the jeopardized region. In conclusion, our data suggest that ischemia-induced myocardial stunning is similar among pigs treated for 3 weeks with atorvastatin, pravastatin, or simvastatin, even though statin treatment appears to augment endothelium-dependent vasodilation of conductance, but not resistance, vessels subjected to ischemia–reperfusion.Key words: ischemia, reperfusion, statins, vascocontriction–dilation, ventricular function.
Attenuation of the serotonin-induced increase in intracellular calcium in rat aortic smooth muscle cells by sarpogrelate
Authors: Saini Harjot K , Sharma Sushil K , Zahradka Peter , Kumamoto Hideo , Takeda Nobuakira , Dhalla Naranjan S
Published: January 2004

Although serotonin (5-HT) induced proliferation of vascular smooth muscle cells is considered to involve changes in intracellular Ca2+([Ca2+]i), the mechanism of Ca2+mobilization by 5-HT is not well defined. In this study, we examined the effect of 5-HT on rat aortic smooth muscle cells (RASMCs) by Fura-2 microfluorometry for [Ca2+]imeasurements. 5-HT was observed to increase the [Ca2+]iin a concentration- and time-dependent manner. This action of 5-HT was dependent upon the extracellular concentration of Ca2+([Ca2+]e) and was inhibited by both Ca2+channel antagonists (verapamil and diltiazem) and inhibitors of sarcoplasmic reticular Ca2+pumps (thapsigargin and cyclopia zonic acid). The 5-HT-induced increase in [Ca2+]iwas blocked by sarpogrelate, a 5-HT2A-receptor antagonist, but not by different agents known to block other receptor sites. 5-HT-receptor antagonists such as ketanserin, cinanserin, and mianserin, unlike methysergide, were also found to inhibit the 5-HT-induced Ca2+mobilization, but these agents were less effective in comparison to sarpogrelate. On the other hand, the increase in [Ca2+]iin RASMCs by ATP, angiotensin II, endothelin-1, or phorbol ester was not affected by sarpogrelate. These results indicate that Ca2+mobilization in RASMCs by 5-HT is mediated through the activation of 5-HT2Areceptors and support the view that the 5-HT-induced increase in [Ca2+]iinvolves both the extracellular and intracellular sources of Ca2+.Key words: sarpogrelate, serotonin, vascular smooth muscle cells, intracellular Ca2+.
Effects of chronic AICAR administration on the metabolic and contractile phenotypes of rat slow- and fast-twitch skeletal muscles
Authors: Bamford Jeremy A , Lopaschuk Gary D , MacLean Ian M , Reinhart Marcia L , Dixon Walter T , Putman Charles T
Published: January 2004

The present study examined the effects of chronic activation of 5'-AMP-activated protein kinase (AMPK) on the oxidative capacity and myosin heavy chain (MHC) based fibre phenotype of rodent fast- and slow-twitch muscles. Sprague–Dawley rats received daily injections for 4 weeks of the known AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) or vehicle (control). The AICAR group displayed increases in hexokinase-II (HXK-II) activity, expression, and phosphorylation in fast-twitch muscles (P < 0.001) but not in the slow-twitch soleus (SOL). In the AICAR group, citrate synthase (EC 4.1.3.7) and 3-hydroxyacyl-CoA-dehydrogenase (EC 1.1.1.35) were elevated 1.6- and 2.1-fold (P < 0.05), respectively, in fast-twitch medial gastrocnemius (MG), and by 1.2- and 1.4-fold (P < 0.05) in the slower-twitch plantaris (PLANT). No changes were observed in the slow-twitch SOL. In contrast, the activity of glyceraldehyde phosphate dehydrogenase (EC 1.2.1.12) remained unchanged in all muscles. AICAR treatment did not alter the MHC-based fibre type composition in fast- or slow-twitch muscles, as determined by immunohistochemical and electrophoretic analytical methods or by RT–PCR. We conclude that chronic activation of AMPK mimics the metabolic changes associated with chronic exercise training (increased oxidative capacity) in the fast-twitch MG and PLANT, but does not coordinately alter MHC isoform content or mRNA expression.Key words: AMP-activated protein kinase, myosin heavy chain, metabolism, RT–PCR, SDS–PAGE.
Evaluation of the effect of gamma rays on the venom of Vipera lebetina by biochemical study
Authors: Bennacef-Heffar Nouara , Laraba-Djebari Fatima
Published: January 2004

Snake bites represent a serious public health problem in many areas of the world. In Algeria, two widespread snakes are Vipera lebetina and Cerastes cerastes. Vipera lebetina venom causes local hemorrhage and necrosis, and it may lead to permanent limb loss. The principal causes of mortality after snakebites are acute renal failure and hemorrhage, which occur not only locally, at the site of the bite, but also systemically, contributing to the cardiovascular shock characteristic of severe envenomation. Gamma radiation has been shown to be effective for attenuating venom toxicity. Vipera lebetina venom was irradiated with two doses of gamma rays (1 and 2 kGy) from a 60Co source, and the venom's toxic, enzymatic, and structural properties were analyzed. Intraperitoneal injection of the irradiated venoms (100–500 µg/20 g mouse body mass) revealed a significant decrease of the toxicity. Irradiated venoms with 1 and 2 kGy doses were four and nine times less toxic, respectively, than the native venom. A biochemical characterization of in vitro enzymatic activities was performed. Vipera lebetina displayed in vitro caseinolytic, amidolytic, esterasic, coagulant, and phospholipase A2 activities. Caseinolytic, amidolytic, esterasic, and coagulative activities were reduced for the irradiated venoms; only phospholipase A2 activity was abolished in the irradiated venom with a dose of 2 kGy. The native and irradiated venoms were separated by gel filtration and electrophoresis. Chromatographic and electrophoretic profiles were drastically changed as compared with the native venom. Vipera lebetina venom detoxified by gamma rays was used for active immunization, and the presence of antibody in the immune sera was detected by ELISA. The immunogenic properties were preserved and the antisera obtained with the irradiated venoms could cross-react. Antisera were able to neutralize the toxic effect of V. lebetina native venom. These results indicate that irradiation of V. lebetina venom with a dose of 2 kGy can promote a significant detoxification, keeping the immunological properties intact.Key words: Vipera lebetina venom, gamma radiation, enzymes, detoxification, immune sera, immunoreactivity.
Effect of gamma irradiation on toxicity and immunogenicity ofAndroctonus australis hectorvenom
Authors: Abib Lila , Laraba-Djebari Fatima
Published: January 2004

An investigation was made of the radiosensitivity of the toxic and immunological properties of Androctonus australis hector venom. This venom was irradiated with two doses of gamma rays (1 and 2 kGy) from a60Co source. The results showed that venom toxicity was abolished for the two radiation doses (1 and 2 kGy) with, respectively, 10 and 25 times its initial LD50 value. However, irradiated venoms were immunogenic, and the antibodies elicited by them were able to recognize the native venom by enzyme-linked immunosorbent assay. Antisera raised against these toxoids (1 and 2 kGy) had a higher neutralizing capacity and immunoreactivity against all components of native venom than did the antiserum produced against the native venom. The antiserum of rabbits immunized with 2-kGy-irradiated venom was more efficient than 1-kGy-irradiated toxoid antiserum. Indeed, in vivo protection assays showed that the mice immunized with 2-kGy-irradiated venom resisted lethal doses (i.p.) of A. australis hector venom.Key words: venom, Androctonus australis hector, gamma irradiation, immunogenicity, in vivo protection.
Dependence of cyclopiazonic-acid-induced muscle contractures on extracellular Ca2+
Authors: Hong S J , Liang Hsiu-Chuan , Shen Ching-Jung
Published: January 2004

Inhibition of Ca2+uptake by the sarcoplasmic reticulum decreases cytosolic Ca2+clearance and also triggers Ca2+influx in response to Ca2+store depletion. The role of extracellular Ca2+in the contractures evoked by cyclo piazonic acid (CPA) and thapsigargin (TG), Ca2+pump inhibitors, was assessed in mouse diaphragm. At 3–100 µM, CPA elicited a rapid-onset contracture followed by a large elevation of muscle tone, which corresponded temporally to the monophasic slow contracture evoked by TG (1–30 µM). Irrespective of the differences in profiles, contractures were prevented and inhibited by the removal of extracellular Ca2+, but not by nicardipine and SK&F96365, blockers of voltage-gated (L-type) and receptor-operated Ca2+channels. Mn2+and Ni2+preferentially depressed the fast-phase contracture, whereas long-term pretreatment with LY294002, U73122, and 2-aminoethoxydiphenylborance, inhibitors of phosphatidylinositol kinase, phospholipase C, and inositol trisphosphate receptors, suppressed the slow-phase contrac ture. When contracture was inhibited, the twitch response remained augmented and prolonged by CPA and TG, indicating that the inhibition was not due to malfunction of the contractile apparatus. For preparations incubated in Ca2+-free medium containing CPA, a monophasic fast upstroke of muscle tone developed as extracellular Ca2+was restored. The results suggest that the bimodal contracture induced by CPA is mediated by the recruitment of distinct Mn2+- and U73122-sensitive Ca2+entries. The ongoing two-component Ca2+entries might merge if the muscle preparation was preconditioned with CPA in Ca2+-free medium to deplete cellular Ca2+stores.Key words: thapsigargin, LY294002, U73122, sarcoplasmic reticulum, 2-aminoethoxydiphenylborane, inositol trisphosphate receptor.
Comparative study of perturbations of peripheral markers in different stressors in rats
Authors: Rai Deepak , Bhatia Gitika , Sen Tuhinadri , Palit Gautam
Published: January 2004

Stress has been implicated in the etiopathogenesis of several diseases. In the present study, the effects of acute (AS), chronic (CS), and chronic unpredictable stress (CUS) were studied on the ulcer index, adrenal gland mass, and biochemical and hormonal changes in rats. The stress was provided in the form of immobilization — immobilization for 150 min, once only, and for 10 consecutive days in CS and CUS. In CUS, animals received variable unpredictable stressors. Immediately after stress, animals were decapitated, blood was collected, and plasma was separated for the esti ma tion of plasma glucose, triglyceride, cholesterol, creatine kinase (CK), corticosterone, and insulin. The adrenal gland and stomach were also dissected for mass and ulcer scoring, respectively. AS significantly increased the ulcer index, plasma glucose, CK, corticosterone, and insulin. CS and CUS significantly increased the ulcer index, adrenal gland mass, and corticosterone. In CS, a significant decrease in plasma triglyceride and cholesterol levels was found, but in CUS only cholesterol was decreased significantly. High CK activity and hyperglycemia maintain the energy demands of metabolism, and elevated corticosterone desensitizes the insulin receptor in AS. In CS and CUS, prolonged elevation of corticosterone shifts metabolism to utilization of lipids as a secondary substrate by gluconeogenesis. From our experiment, it is clear that AS causes maximum activation of energy metabolism, which becomes specific after habituation in prolonged CS. These biochemical manipulations in the body by using different types of stressors are good markers that can be of great use to understand, target, and manage stress-induced etiologies.Key words: stress, adrenal hypertrophy, hormones, glucose, lipids, creatine kinase.
Thyrotropin and iodide regulate sulfate concentration in thyroid cells. Relationship to thyroglobulin sulfation
Authors: Cauvi David , Venot Nicole , Nlend Marie-Christine , Chabaud Odile M
Published: January 2004

Thyroglobulin (Tg), the thyroid hormone precursor, is sulfated both on tyrosines and on carbohydrates. We showed recently that sulfated tyrosines were involved in thyroid hormone synthesis. Moreover, we also reported that Tg sulfation is downregulated by thyrotropin (TSH), especially on tyrosines. This control may occur at each step in the sulfation process. In this paper, we studied the regulation of the concentration of cytosolic inorganic sulfate, the first substrate, in porcine thyroid cells stimulated by TSH with or without iodide. The amounts of cytosolic sulfate and the cytosolic volumes measured showed that the sulfate concentration depends only on cytosolic volume changes in response to TSH and iodide treatment. After the cells were labelled with [35S]-sulfate, the specific radioactivity (SRA) of cytosolic sulfate was determined. When cells were treated with only TSH, the concentration and SRA of cytosolic sulfate decreased by 30%, and by about 15% when cells were incubated with both TSH and iodide. TSH decreased more conspicuously the rate of [35S]-sulfate incorporation into Tg (by 57% without iodide, by 43% with iodide) than the concentration and SRA of cytosolic sulfate, while iodide altered these parameters to the same extent (15%). These findings suggest that TSH regulates other steps in the sulfation process, such as specific substrate and enzyme levels, while iodide controls mainly the sulfate concentration.Key words: cytosolic inorganic sulfate measurement, capillary electrophoresis, intracellular sulfate concentration, thyroglobulin sulfation, primary culture thyroid cells.
Effects of 60Co gamma radiation on toxicity and hemorrhagic, myonecrotic, and edema-forming activities of Cerastes cerastes venom
Authors: Abib Hinda , Laraba-Djebari Fatima
Published: January 2004

Antisera are used as effective antidotes against the local effects of snake bites. To improve antisera production and extend the life of surrogates used to produce antibodies, the chronic effects of venom toxicity must be reduced. The present study evaluated the effectiveness of gamma irradiation to reduce the local effects associated with viperid snake bites by evaluating in NMRI mice the toxicity and edematic, hemorrhagic, and myonecrotic activities of native and irradiated Cerastes cerastes venoms. These results indicated that the toxicity of irradiated venoms (1 and 2 kGy) decreased as compared with that of native venom. The edematic and hemorrhagic activities were also reduced in the detoxified samples, particularly with the 2-kGy radiation dose. Futhermore, the creatine phosphokinase (CPK) activity was significantly increased in the serum and decreased in the myocardium after envenomation with native venom, but no significant enzymatic changes were observed in mice envenomated with irradiated venom. Histopathologic evaluation showed that native venom caused severe degenerative changes in the myocardium. In the case of 2-kGy-irradiated venom, no tissue alterations were observed. These results indicate that irradiation of venom with a 2-kGy dose may offer an effective method for reducing the chronic toxic effects of venom in immunized animals.Key words: venom, Cerastes cerastes, gamma radiation, histopathological change.
Fossorial life constrains microhabitat selection of the amphisbaenian Trogonophis wiegmanni
Authors: Civantos Emilio , Martín José , López Pilar
Published: January 2004

We present a field study designed to characterize microhabitat selection in a population of Trogonophis wiegmanni, a fossorial reptile that is the only representative of the family Trogonophidae in North Africa. Our results show that T. wiegmanni used microhabitats in proportion to their availability with one exception: they showed a preference for areas with 5–10 cm high vegetation cover (i.e., perennial bushes and scrubs such as Atriplex halimus, Lycium intricatum, and Suaeda vera, and herbs such as Lavatera mauritanica and Malva parviflora). They avoided areas with abundant small stones, indicating that at least some structural characteristics of the microhabitat occupied by amphis bae nians seem to be different from those available. Our data also show that T. wiegmanni selected thinner and wider rocks than those rocks found randomly. Such choices could have important thermoregulatory consequences.
Phylogeny of Palaearctic Pharyngodonidae parasite species of Testudinidae: a morphological approach
Authors: Bouamer Salah , Morand Serge
Published: January 2004

The phylogenetic relationships of 23 oxyurid species from five genera (21 parasite species of the Palaearctic Testudinidae, 1 parasite species of Uromastix acanthinurus Bell, 1825 from Algeria, and 1 parasite species of Cteno sa ura pectinata (Wiegmann, 1834) from Mexico) were investigated using 30 morphological characters obtained from species descriptions. The nonweighted analysis produced one shortest tree. All species of the ingroup form a monophyletic group and the oxyurid species of Testudinidae form a monophyletic group. The type species of the genus Alaeuris Thapar, 1925 is the basal member of the species parasitizing Testudinidae. The analysis confirms the monophyly of the genus Thaparia Ortlepp, 1933, whereas the genera Mehdiella Seurat, 1918 and Tachygonetria Wedl, 1862 are considered paraphyletic groups. The large diversification in the genus Tachygonetria is linked to their position in the host caecum. The ancestral state is in the paramucous and the derived state is in the centre of the caecum. This suggests that recent speciation in the group occurs in the centre of the caecum.
Does living in streams with fish involve a cost of induced morphological defences?
Authors: Dahl Jonas , Peckarsky Barbara L
Published: January 2004

Previous studies have shown that chemical cues from brook trout (Salvelinus fontinalis) induce relatively longer caudal filaments and heavier exoskeletons in the mayfly Drunella coloradensis. These characters constitute morphological defences that reduce larval mortality from brook trout predation. There is also a potential fitness cost of living in streams with trout, as D. coloradensis females emerge at smaller sizes from streams with fish compared with females in streams without fish. In this study, we obtained additional data to evaluate the hypothesis that these costs of living in streams with fish could be attributed to inducible defences. A field survey of seven different streams showed that mature (black wing pad) female larvae from streams with fish invested a smaller proportion of their body mass in eggs than females maturing in streams without fish. Furthermore, a negative relationship between female allocation to eggs and to morphological defence characters (relative length of the caudal filament) provides evidence of a cost of inducible defences in this species.
A test of hypotheses based on optimal foraging considerations for a diving mammal using a novel experimental approach
Authors: Cornick Leslie A , Horning Markus
Published: January 2004

The response of marine predators to changes in fine-scale prey distribution is poorly understood. Precipitous declines in marine apex predators necessitate a better understanding of the magnitude of fluctuations in prey availability that are within the compensatory behavioural plasticity of predators. We experimentally manipulated the fine-scale prey field for a marine carnivore in a controlled, captive setting and examined changes in behaviour and efficiency with changes in prey encounter rate. We hypothesized (i) a minimum prey encounter rate below which the cost of foraging always exceeds the benefit, (ii) foraging effort should increase with increasing prey encounter rates, and (iii) a maximum threshold prey encounter rate at which foraging efficiency is optimized. Dive duration, foraging time, and dive and foraging efficiency increased significantly with increasing prey encounter rate up to an asymptote of ~13 fish per dive cycle, supporting two of the three hypotheses. The results also support predicted responses to changing prey encounter rates derived from an optimal foraging model for diving animals and are the first experimental validation of optimal foraging model predictions in a marine mammal. We believe that these results provide new insight and suggest new experimental techniques for examining the foraging ecology of large marine predators.
Ankylosis patterns in the postcranial skeleton and hyoid bones of the harbour porpoise (Phocoena phocoena) in the Baltic and North Sea
Authors: Galatius Anders , Kinze Carl Christian
Published: January 2004

The onset and timing of epiphyseal ankylosis in the vertebral column and flippers and ankylosis of the hyoid and sternal bones were studied in 350 skeletons of the harbour porpoise (Phocoena phocoena) originating from the Baltic and North Sea and held in the collections of the Zoological Museum (University of Copenhagen), the Museum of Natural History (Gothenburg), the National Museum of Natural History (Stockholm), and the German Oceanographic Museum (Stralsund). Epiphyseal ankylosis in the vertebral column started in the anterior cervical region and then initiated around the 23rd to 26th caudal vertebrae from where it proceeded in both directions. The progression of vertebral epiphyseal ankylosis eventually terminated in the thoracic and lumbar regions. Epiphyseal ankylosis in the flippers began at the distal end of the humerus and the proximal ends of the radius and ulna. The timing of ankylosis in the flippers was more consistent across the specimens than the timing of vertebral ankylosis. Males and females had similar timing of ankylosis in the vertebral column and the flippers. Complete fusion of the hyoid and sternal bones occurred within the first year of life in most specimens. The early development of the hyoid apparatus may be linked to use of suction in feeding.
Lizard community structure across a grassland – creosote bush ecotone in the Chihuahuan Desert
Authors: Menke Sean B
Published: January 2004

I investigated the distribution and abundance of lizard species (Aspidoscelis inornatus, Aspidoscelis tesselatus, Aspidoscelis tigris, Aspidoscelis uniparens, Cophosaurus texanus, Crotaphytus collaris, Eumeces obsoletus, Gambelia wislizenii, Holbrookia maculata, Phrynosoma cornutum, Sceloporus magister, and Uta stansburiana) across a desert grassland – creosote bush (Larrea tridentata) ecotone in Dona Ana County, New Mexico. The ecotonal area in the Jornada del Muerto basin has increased dramatically in the past 150 years because of the rapid spread of creosote bush. I asked four related questions: how large and where is the ecotone based on vegetative structure, and do lizard abundance and diversity change across the ecotone? Vegetation data were analyzed using discriminate function analysis to determine the extent of the ecotone. Changes in lizard abundance across the ecotone were analyzed by analysis of variance. During two summers, 677 individual lizards of 9 genera and 12 species were captured. Lizard abundance increased with increasing distance from the ecotone and was similar in grassland and creosote bush habitat. Grasslands had higher species richness than both the creosote bush and ecotone habitats. Grassland sites had greater habitat heterogeneity than did creosote bush sites. No ecotone specialist species were detected, and all common lizard species could be found in each habitat. Three potential explanations for decreased abundance in the ecotone are presented: (1) increased risk of predation, (2) decreased prey abundance, and (3) lack of species-specific microhabitat requisites.
A REMARK ON A QUESTION OF LEMPERT–HENKIN
Authors: NGUYÊN VIÊT ANH
Published: January 2004

We investigate a question raised by Lempert–Henkin on the regularity of the [Formula: see text] equation on infinite dimensional spaces. More precisely, we improve slightly a classical example of Coeuré–Lempert.
ON BRANCHED COVERINGS OF ℙn BY PRODUCTS OF DISCS
Authors: MUHAMMED ULUDAĞ A.
Published: January 2004

For any n>1, we construct examples of branched Galois coverings M→ℙn where M is one of (ℙ1)n, [Formula: see text] and [Formula: see text], where [Formula: see text] is the 1-ball. In terms of orbifolds, this amounts to giving examples of orbifolds over ℙn uniformized by M. We also discuss the related "orbifold braid groups".
STABLE RANK-2 BUNDLES ON CALABI–YAU MANIFOLDS
Authors: LI WEI-PING , QIN ZHENBO
Published: January 2004

In this paper, we apply the technique of chamber structures of stability polarizations to construct the full moduli space of rank-2 stable sheaves with certain Chern classes on Calabi–Yau manifolds which are anti-canonical divisor of ℙ1×ℙnor a double cover of ℙ1×ℙn. These moduli spaces are isomorphic to projective spaces. As an application, we compute the holomorphic Casson invariants defined by Donaldson and Thomas.