bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro degradation of hexanitrohexaazaisowurtzitane (CL-20) by cytosolic enzymes of Japanese quail and the rabbit
Authors: Bardai Ghalib K. , Halasz Annamaria , Sunahara Geoffrey I. , Dodard Sabine , Spear Philip A. , Grosse Stephan , Hoang Johnston , Hawari Jalal 
Published: December 2006

Abstract
Hexanitrohexaazaisowurtzitane (CL-20) is a polycyclic nitramine explosive and propellant, currently being considered as a potential replacement for existing cyclic nitramine explosives. Earlier studies have provided evidence suggestive of adverse liver effects in adult Coturnix spp. exposed to CL-20, yet analysis of tissue samples (plasma, liver, brain, heart, or spleen) indicated that CL-20 was not detectable in these treated animals. The present study was conducted to identify and purify the enzymes capable of CL-20 biotransformation. Results indicate that the hepatic biotransformation of CL-20 in vitro was inhibited by ethacrynic acid (93%) and by the glutathione (GSH) analogue S-octylglutathione (80%), suggesting the involvement of glutathione-S-transferase (GST). Partially purified cytosolic α- and μ-type GST (requiring presence of GSH as a cofactor) from quail and rabbit liver was capable of CL-20 biotransformation. The degradation of CL-20 (0.30 ± 0.05 and 0.40 ± 0.02 nmol/min/mg protein for quail and rabbit, respectively) was accompanied with the formation of nitrite and consumption of GSH. Using liquid chromatography/mass spectrometry, we detected two intermediates, that is, open-ring, monodenitrated GSH–conjugated CL-20 biotransformation product with the same deprotonated molecular mass ion at 699 Da, suggesting isomeric forms of the intermediate metabolites. Identity of the conjugated metabolites was confirmed by using ring-labeled [15N]CL-20 and the nitro group–labeled [15NO2]CL-20. These data suggest that the in vitro biotransformation of CL-20 by GST under the conditions tested may be a key initial step in the in vivo degradation of CL-20 in the quail and resulted in the formation of more biologically reactive intermediates than the parent compound. These data will aid in our understanding of the biotransformation processes of CL-20 in vivo.
Physiological modes of action of toxic chemicals in the nematodeAcrobeloides nanus
Authors: Álvarez Olga Alda , Jager Tjalling , Redondo Eliana Marco , Kammenga Jan E. 
Published: December 2006

AbstractTo gain a better understanding of the mechanisms through which a chemical exerts toxicity, a deeper insight is needed regarding the physiological processes that take place during a toxic stress. This issue can have important benefits for risk assessment, because it can contribute to a better interpretation of toxicity data. Here, we study the physiological mode of action of three different compounds (cadmium, carbendazim, and pentachlorobenzene) with an experimental data–based approach using whole life-cycle toxicity data from the nematode Acrobeloides nanus. We use a process–based model, based on the dynamic energy budget theory, to study the fluxes of energy related to physiological processes and their variation throughout the life cycle. With this approach, we unravel the physiological modes of action based on resource allocation, and we model the effects of the different modes of action at the population level. The mode of action of carbendazim was through a decrease in assimilation, with an additional effect on the production of reactive oxygen species (ROS). Cadmium increased the costs of growth, with an extra effect on ROS production, and pentachlorobenzene decreased assimilation. We compared the present results with those of previous studies using the nematode Caenorhabditis elegans, and we found that the modes of action for the three compounds differed from those found in A. nanus, showing that the life-history characteristics of each organism have a clear influence on the resulting modes of action. This highlights the importance of the interactions between a chemical and the biological characteristics of the organism in determination of the resulting physiological modes of action.
Volatile organic sulfur compounds in anaerobic sludge and sediments: Biodegradation and toxicity
Authors: van Leerdam Robin C. , de Bok Frank A. M. , Lomans Bart P. , Stams Alfons J. M. , Lens Piet N. L. , Janssen Albert J. H. 
Published: December 2006

Abstract
A variety of environmental samples was screened for anaerobic degradation of methanethiol, ethanethiol, propanethiol, dimethylsulfide, and dimethyldisulfide. All sludge and sediment samples degraded methanethiol, dimethylsulfide, and dimethyldisulfide anaerobically. In contrast, ethanethiol and propanethiol were not degraded by the samples investigated under any of the conditions tested. Methanethiol, dimethylsulfide, and dimethyldisulfide were mainly degraded by methanogenic archaea. In the presence of sulfate and the methanogenic inhibitor bromoethane sulfonate, degradation of these compounds coupled to sulfate reduction occurred as well, but at much lower rates. Besides their biodegradability, also the toxicity of methanethiol, ethanethiol, and propanethiol to methanogenesis with methanol, acetate, and H2/CO2 as the substrates was assessed. The 50% inhibition concentration of methanethiol on the methane production from these substrates ranged between 7 and 10 mM. The 50% inhibition concentration values of ethanethiol and propanethiol for the degradation of methanol and acetate were between 6 and 8 mM, whereas hydrogen consumers were less affected by ethanethiol and propanethiol, as indicated by their higher 50% inhibition concentration (14 mM). Sulfide inhibited methanethiol degradation already at relatively low concentrations: methanethioldegradation was almost completely inhibited at an initial sulfide concentration of 8 mM. These results define the operational limits of anaerobic technologies for the treatment of volatile organic sulfur compounds in sulfide-containing wastewater streams.
Assimilation of cadmium in a European lacertid lizard: Is trophic transfer important?
Authors: Mann Reinier M. , Serra Elisabete A. , Soares Amadeu M. V. M. 
Published: December 2006

Abstract
Apart from analyses for elemental contaminants in field-collected specimens, very little is known about the assimilation and accumulation of inorganic contaminants in reptiles. Recent dietary studies with reptiles (and some other vertebrates and invertebrates) have taken care to incorporate the principles of trophic transfer by pre-exposing prey items to the elemental contaminant of interest. However, there are conflicting data in the literature as to whether biologically incorporated metals are more bioavailable to consumers in a food chain than simple salts added to the diet, and this study examines this issue in a lacertid lizard. Adult individuals of Podarcis carbonelli were exposed to cadmium (Cd) in a 21-week dietary study to determine whether the form in which the Cd is provided influences assimilation efficiency for this metal. Lizards were provided with Cd that had either been biologically incorporated into crickets or as Cd(NO3)2 added superficially to crickets just prior to feeding. Radiospectrometric analysis for 109Cd in animal tissues and fecal material was used to follow Cd accumulation over the duration of exposure. The highest levels of accumulation were found within the gut. This, combined with the observation of higher rates of assimilation over the first five weeks, strongly suggests a rapid accumulation of Cd within the gut tissue followed by a slower redistribution to other tissues. No statistically different levels of Cd assimilation efficiency were detected between the two treatment groups, nor were there any statistically significant differences between the two treatment groups in relation to the proportional distribution to the gut, liver, or kidneys.
Toxic effects and oxidative stress in higher plants exposed to polycyclic aromatic hydrocarbons and their N-heterocyclic derivatives
Authors: Pašková Veronika , Hilscherová Klára , Feldmannová Marie , Bláha Luděk 
Published: December 2006

Abstract
N-heterocyclic derivatives of polycyclic aromatic hydrocarbons (NPAHs) are widespread concomitantly with their parent analogues and have been detected in air, water, sediments, and soil. Although they were shown to be highly toxic to some organisms, our understanding of their occurrence, environmental fate, biological metabolism, and effects is limited. This study evaluated toxic effects of three homocyclic aromatic hydrocarbons (PAHs—phenanthrene, anthracene, fluorene) and their seven N-heterocyclic derivates on higher terrestrial plants Sinapis alba, Triticum aestivum, and Phaseolus vulgaris. Germinability, morphological end-points, parameters of detoxification, and antioxidant components of plant metabolism as well as lipid peroxidation were studied in acute phytotoxicity tests. Phytotoxicity of NPAHs was generally more pronounced than the effects of parent PAHs, and it significantly differed with respect to the structure of individual NPAHs. Sinapis alba and T. aestivum were more sensitive plant species than P. vulgaris. Chemicals with the strongest inhibition effect on germination and growth of plants were phenanthridine, acridine, benzo[h]quinoline, and 1,10- and 1,7-phenanthroline. All tested chemicals significantly induced activities of detoxification and antioxidant enzymes (glutathione reductase, glutathione peroxidase, and glutathione-S-transferase) at nanomolar to low micromolar concentrations. Levels of reduced glutathione were induced by all tested chemicals except 1,10- and 4,7-phenanthroline. Furthermore, fluorene, carbazole, acridine, phenanthrene, phenanthridine, benzo[h]quinoline, and 1,7-phenanthroline significantly increased lipid peroxidation. The results of our study newly demonstrate significant toxicity of NPAHs to plants and demonstrate suitability of multiple biomarker assessment to characterize mechanisms of oxidative stress and to serve as an early warning of phytotoxicity in vivo.
Arsenate sorption on two chinese red soils evaluated with macroscopic measurements and extended X-ray absorption fine-structure spectroscopy
Authors: Luo Lei , Zhang Shuzhen , Shan Xiao-Quan , Jiang Wei , Zhu Yong-Guan , Liu Tao , Xie Ya-Ning , McLaren Ronald G. 
Published: December 2006

Abstract
Arsenic sorption is the primary factor that affects the bioavailability and mobility of arsenic in soils. To elucidate the characteristics and mechanisms of arsenate, As(V), sorption on soils, a combination of sorption isotherms, zeta potential measurements, and extended X-ray absorption fine-structure (EXAFS) spectroscopy was used to investigate As(V) sorption on two Chinese red soils. Arsenate sorption increased with increasing As(V) concentration and was insensitive to ionic strength changes at pH 6.0. Arsenate, mainly as H2AsO4– in soil solution at pH 6.0, was strongly sorbed mainly through ligand exchange by the two soils. The sorption capacity was affected by the iron and aluminum mineral contents in the soils. The zeta potential measurements showed that As(V) sorption lowered the zeta potential and the points of zero charge of the soils. The EXAFS data indicate that adsorbed As(V) forms inner-sphere complexes with bidentate–binuclear configurations, as evidenced by an As–Fe bond distance of 3.28 ± 0.04 Å and an As–Al bond distance of 3.17 ± 0.03 Å. The two As(V) complexes were stable at different As(V) loadings, whereas the proportions were related to the aluminum and iron mineral contents in the soils. This study illuminated the importance of inclusion of microscopic and macroscopic experiments to elucidate sorption behavior and mechanisms.
Examining multiple sublethal contaminants on the gray treefrog (Hyla versicolor): Effects of an insecticide, herbicide, and fertilizer
Authors: Boone Michelle D. , Bridges-Britton Christine M. 
Published: December 2006

Abstract
We examined the single and interactive effects of an insecticide, an herbicide, and a fertilizer on gray treefrog (Hyla versicolor) tadpoles. Tadpoles were reared in mesocosms from hatching through metamorphosis and were exposed to the presence or absence of as many as three contaminants. Tadpoles did not appear to be more susceptible to single versus multiple contaminants, which may result from positive changes in food resources that compensate for the effects of other contaminants.
A multidisciplinary approach to determine the structural geometry of hard-rock aquifers. Application to the Plancoet migmatitic aquifer (NE Brittany, W France)
Authors: Durand Véronique , Deffontaines Benoît , Leonardi Véronique , Guerin Roger , Wyns Robert , de Marsily Ghislain , Bonjour Jean-Luc 
Published: December 2006

Abstract
A new multidisciplinary methodology is developed to determine the structural geometry of hard-rock aquifers. The Plancoët migmatitic basement, chosen as an example for the use of this methodology, is studied both at a regional (300 km2) and a local (4 km2) scale. The regional mapping, based on field mapping of the tectonic structures and the weathered layers, on geostatistics and on aerial photographs and Digital Elevation Model (DEM) analyses, demonstrates the influence of the tectonic structures on the weathering processes. Some geo-electric investigations, added to the first mapping at the local scale, lead to the building of a local geometrical model of the aquifer.
The “Schistes carton” of Quercy (Tarn, France): a lithological signature of a methane hydrate dissociation event in the Early Toarcian. Implications for correlations between Boreal and Tethyan realms
Authors: Emmanuel Laurent , Renard Maurice , Cubaynes René , de Rafelis Marc , Hermoso Michael , Lecallonnec Laurence , le Solleuz Antoine , Rey Jacques 
Published: December 2006

Abstract
The geochemical events (negative shifts in δ13C and δ18O, and Mn peak) associated with the “Schistes carton” of Quercy (SW France) do not appear to be due only to lithological variations and a differential diagenesis. They correspond to the Lower Toarcian global event and seem to be connected to a destabilization phase of gas hydrates. During its oxidation by seawater, the release of methane gas with a very low carbon isotopic ratio (− 60%) led to the production of CO2 and carbonates with a negative δ13C. The consumption of oxygen in the seawater resulted in conditions that were first dysoxic and then anoxic. The reduction of burrowing and bioturbation associated with this oxidation resulted in the laminated appearance of the “Schistes carton”. The decrease in the oxygen content led to a decrease in MnO2 microparticles present in the water column and sediments. This created a complementary source of Mn2+ that was incorporated into the carbonates produced during this event. Furthermore, an increase in the average seawater temperature (δ18O) appears associated with this event. Finally, the apparent diachronism of geochemical events in the Boreal and the Tethyan realms is discussed.
Structural evolution of the external zones derived from the Flysch trough and the South Iberian and Maghrebian paleomargins around the Gibraltar arc: a comparative study
Authors: Crespo-Blanc Ana , de Lamotte Dominique Frizon 
Published: December 2006

AbstractThe Betics and Rif cordillera constitute the northern and southern segments of the Gibraltar arc. Two different fold-and-thrust belts, deriving from the South Iberian and Maghrebian paleomargins respectively, developed in front of this orogenic system. By contrast, the Flysch Trough units and the overlying Alboran crustal domain (internal zones), which are situated in the uppermost part of the orogenic wedge, are common to both branches of the arc. The Flyschs Trough units constitute an inactive accretionary prism, derived from a deep elongated trough. From three large-scale profiles and some lithostratigraphic features of the involved sedimentary sequences, the Betic and Rif external domains are compared, mainly from a structural point of view. Although they are generally considered to show major similarities, the Betic and Rif external domains are in fact strikingly different, mainly concerning the structural style, deformation timing and metamorphism: a) the thick-skinned structure in the External Rif domain vs thin-skinned in the Subbetic domain; b) the pre-Oligocene and Miocene stacking in the External Rif domain vs the exclusively Miocene one in the Subbetic domain, and c) the metamorphism present only in part of the External Rif domain (low-grade greenschists facies). By contrast, it was not possible to establish any difference in structural style and deformation timing between the Flysch units outcropping in both branches of the Gibraltar arc.
Comparison of variability in cardiorespiratory measurements following desflurane anesthesia at a multiple of the minimum alveolar concentration for each dog versus a multiple of a single predetermined minimum alveolar concentration for all dogs in a group
Authors: Pypendop Bruno H. , Ilkiw Jan E. 
Published: December 2006

Abstract
Objective—To determine whether the variability of cardiorespiratory measurements is smaller when administering desflurane at a multiple of the individual's minimum alveolar concentration (MAC) or at a predetermined, identical concentration in all subjects.
Animals—10 dogs.
Procedures—Desflurane was administered at 1.5 times the individual's MAC (iMAC) and 1.5 times the group's MAC (gMAC). The order of concentrations was randomly selected. Heart rate, respiratory rate, arterial blood pressure, central venous pressure, mean pulmonary artery pressure, pulmonary artery occlusion pressure, arterial and mixed-venous blood gas tensions and pH, and cardiac output were measured. The desflurane concentration required to achieve a mean arterial pressure (MAP) of 60 mm Hg was then determined. Finally, the desflurane concentration required to achieve an end-tidal PCO2 of 55 mm Hg was measured.
Results—Variances when administering 1.5 iMAC or 1.5 gMAC were not significantly different for any variable studied. Differences between the MAC multiples needed to reach an MAP of 60 mm Hg and the mean of the sample were significantly larger when gMAC was used, compared with iMAC, indicating that a multiple of iMAC better predicted the concentration resulting in a MAP of 60 mm Hg.
Conclusions and Clinical Relevance—Results suggest that, in a small group of dogs, variability in cardiorespiratory measurements among dogs is unlikely to differ whether an inhalant anesthetic is administered at a multiple of the iMAC in each dog or at an identical gMAC in all dogs.
Effects of ketamine and magnesium on the minimum alveolar concentration of isoflurane in goats
Authors: Queiroz-Castro Patricia , Egger Christine , Redua Marcia A. , Rohrbach Barton W. , Cox Sherry , Doherty Tom 
Published: December 2006

Abstract
Objective—To evaluate the effects of ketamine, magnesium sulfate, and their combination on the minimum alveolar concentration (MAC) of isoflurane (ISO-MAC) in goats.
Animals—8 adult goats.
Procedures—Anesthesia was induced with isoflurane delivered via face mask. Goats were intubated and ventilated to maintain normocapnia. After an appropriate equilibration period, baseline MAC (MACB) was determined and the following 4 treatments were administered IV: saline (0.9% NaCl) solution (loading dose [LD], 30 mL/20 min; constant rate infusion [CRI], 60 mL/h), magnesium sulfate (LD, 50 mg/kg; CRI, 10 mg/kg/h), ketamine (LD, 1 mg/kg; CRI, 25 μg/kg/min), and magnesium sulfate (LD, 50 mg/kg; CRI, 10 mg/kg/h) combined with ketamine (LD, 1 mg/kg; CRI, 25 μg/kg/min); then MAC was redetermined.
Results—Ketamine significantly decreased ISOMAC by 28.7 ± 3.7%, and ketamine combined with magnesium sulfate significantly decreased ISOMAC by 21.1 ± 4.1%. Saline solution or magnesium sulfate alone did not significantly change ISOMAC.
Conclusions and Clinical Relevance—Ketamine and ketamine combined with magnesium sulfate, at doses used in the study, decreased the end-tidal isoflurane concentration needed to maintain anesthesia, verifying the clinical impression that ketamine decreases the end-tidal isoflurane concentration needed to maintain surgical anesthesia. Magnesium, at doses used in the study, did not decrease ISOMAC or augment ketamine's effects on ISOMAC.
Effects of sodium hyaluronate and methylprednisolone acetate on proteoglycan metabolism in equine articular chondrocytes treated with interleukin-1
Authors: Yates Angela C. , Stewart Allison A. , Byron Christopher R. , Pondenis Holly C. , Kaufmann Karissa M. , Constable Peter D. 
Published: December 2006

Abstract
Objective—To determine the effects of sodium hyaluronate (HA) in combination with methylprednisolone acetate (MPA) on interleukin-1 (IL-1)–induced inflammation in equine articular cartilage pellets.
Sample Population—Chondrocytes collected from 7 horses euthanatized for problems unrelated to the musculoskeletal system.
Procedures—Chondrocyte pellets were treated with medium (negative control); medium containing IL-1 (positive control); or medium containing IL-1 with MPA only (0.05 or 0.5 mg/mL), HA only (0.2 or 2 mg/mL), or MPA (0.05 or 0.5 mg/mL) and HA (0.2 or 2 mg/mL) in combination. Proteoglycan (PG) synthesis was determined by incorporation of sulfur 35–labeled sodium sulfate into PGs. Glycosaminoglycan (GAG) content of the media and the pellets and total pellet DNA content were determined.
Results—Methylprednisolone acetate at 0.5 mg/mL caused an increase in PG synthesis, whereas HA had no effect alone. The combination of MPA, both 0.05 mg/mL and 0.5 mg/mL, with HA at 2 mg/mL increased PG synthesis, compared with IL-1–treated control. All treatment groups containing the high concentration of MPA (0.5 mg/mL) and the high concentration of HA (2.0 mg/mL) had pellets with increased GAG content. The addition of HA caused an increase in total GAG content in the media, regardless of MPA treatment. Cyclooxygenase-2 mRNA and aggrecan mRNA expression was significantly reduced with MPA treatment. Total pellet DNA content was unchanged by any treatment.
Conclusions and Clinical Relevance—Our results indicate that MPA in combination with HA has beneficial effects on PG metabolism of IL-1–treated equine chondrocytes.
Distribution of muscarinic receptor subtypes and interstitial cells of Cajal in the gastrointestinal tract of healthy dairy cows
Authors: Stoffel Michael H. , Monnard Christel Wicki , Steiner Adrian , Mevissen Meike , Meylan Mireille 
Published: December 2006

Abstract
Objective—To describe the distribution of muscarinic receptor subtypes M1 to M5 and interstitial cells of Cajal (ICCs) in the gastrointestinal tract of healthy dairy cows.
Sample Population—Full-thickness samples were collected from the fundus, corpus, and pyloric part of the abomasum and from the duodenum, ileum, cecum, proximal loop of the ascending colon, and both external loops of the spiral colon of 5 healthy dairy cows after slaughter.
Procedures—Samples were fixed in paraformaldehyde and embedded in paraffin. Muscarinic receptor subtypes and ICCs were identified by immunohistochemical analysis.
Results—Staining for M1 receptors was found in the submucosal plexus and myenteric plexus. Antibodies against M2 receptors stained nuclei of smooth muscle cells only. Evidence of M3 receptors was found in the lamina propria, in intramuscular neuronal terminals, on intermuscular nerve fibers, and on myocytes of microvessels. There was no staining for M4 receptors. Staining for M5 receptors was evident in the myocytes of microvessels and in smooth muscle cells. The ICCs were detected in the myenteric plexus and within smooth muscle layers. Distribution among locations of the bovine gastrointestinal tract did not differ for muscarinic receptor subtypes or ICCs.
Conclusions and Clinical Relevance—The broad distribution of M1, M3, M5, and ICCs in the bovine gastrointestinal tract indicated that these components are likely to play an important role in the regulation of gastrointestinal tract motility in healthy dairy cows. Muscarinic receptors and ICCs may be implicated in the pathogenesis of motility disorders, such as abomasal displacement and cecal dilatation-dislocation.