bluuebunny/crossref_metadata_2025_split huggingface dataset:
Substrate specificity of rat liver aldehyde dehydrogenase with chloroacetaldehydes
Authors: Sharpe A. L. , Carter D. E. 
Published: October 2006

AbstractChlorinated acetaldehydes have been the focus of research due to their role as reactive intermediates and their possible occurrence in chlorinated drinking water. This study investigated the in vitro substrate specificity of cytosolic and mitochondrial rat liver aldehyde dehydrogenase toward these compounds. Monochloroacetaldehyde was found to be extensively metabolized by these enzymes, to an even greater extent than the standard substrate propionaldehyde. Dichloroacetaldehyde was metabolized to a much lesser extent, and chloral hydrate is not metabolized by this enzyme family. The KmM (mM) and Vmax (Vmax for propionaldehyde set to 100) values with the low Km cytosolic enzyme were monochloroacetalde‐hyde 0.046. and 582, and dichloroacetaldehyde 0.13 and 54.9, and those with the high Km cytosolic en zyme were dichloroacetaldehyde 0.35 and 23.4. The values with the low Km mitochondrial enzyme were monochloroacetaldehyde 0.057 and 462 and dich loroacetaldehyde 0.038 and 12.9, and those with the high Km mitochondrial enzyme were monochloroacetaldehyde 0.024 and 55.5 and dichloroacetaldehyde 0.29 and 3.44. These data suggest that aldehyde dehydrogenase plays a significant role in the metabolism of monochloroacetaldehyde and, to some extent, dichloroacetaldehyde. Some evidence also suggested that alcohol dehydrogenase plays a significant role in the metabolism of dich loroacetaldehyde and chloral hydrate.
Changes in brain enkephalin immunostaining after acute carbon disulfide exposure in rats
Authors: de Gandarias J. M. , Echevarría E. , Múgica J. , Serrano R. , Casis L. 
Published: October 2006

AbstractCarbon disulfide neurotoxic mechanism in the brain is still not completely clear. In this work, the effect of carbon disulfide exposure in rats on the enkephalinergic neuromodulatory system is described. Caudatus‐putamen showed no changes in immunostaining for met‐enkephalin when compared with controls. However, a marked reduction in met‐enkephalin immunostaining in the central amygdaloid nuclei and the globus pallidus was measured, with a parallel elevation in the lateral septal nucleus and the parietal cortex. It is suggested that enkephalinergic neuromodulatory system could play a role in carbon disulfide neurotoxicity.
The role of cytochrome P450 2C3 in rabbit liver microsomal metabolism of 1‐nitropyrene and 3‐nitrofluoranthene
Authors: Howard Paul C. , McManus Michael E. , Koop Dennis R. 
Published: October 2006

AbstractThe male rabbit liver microsomal cytochrome P450 metabolism of 1‐nitropyrene and 3‐nitrofluoranthene was investigated. In this study, we used inhibitory antibodies specific for rabbit P450 2C3 and determined that, in untreated male rabbit liver microsomes, the antibody inhibited approximately 75% of the cytochrome P450‐mediated C‐oxidation of both 1‐nitropyrene and 3‐nitrofluoranthene. These results verify our previous prediction that mainly one cytochrome P450 is responsible for microsomal metabolism of 1‐nitropyrene in the untreated rabbit liver.
Inhibition studies on the involvement of flavoprotein reductases in menadione‐ and nitrofurantoin‐stimulated oxyradical production by hepatic microsomes of flounder (Platichthys flesus)
Authors: Lemaire Philippe , Livingstone David R. 
Published: October 2006

AbstractInhibitors of mammalian cytochrome P450 and P450 reductase were used to investigate the enzymes in flounder (Platichthys flesus) hepatic microsomes involved in the stimulation of NAD(P)H‐dependent iron/EDTA‐mediated 2‐keto‐4‐methiolbutyric acid (KMBA) oxidation (hydroxyl radical production) by the redox cycling compounds menadione and nitrofurantoin. Inhibitors were first tested for their effects on flounder microsomal P450 and flavoprotein reductase activities. Ellipticine gave type II difference binding spectra (app. Ks 5.36 μM; ΔA max 0.16 nmol‐1 P450) and markedly inhibited NADPH‐cytochrome c reductase, NADPH‐cytochrome P450 reductase, and monooxygenase (benzo[a]pyrene metabolism) activities. 3‐aminopyridine adenine dinucleotide phosphate (AADP; competitive inhibitor of P450 reductase) inhibited NADPH‐cytochrome c but not NADH‐cytochrome c or NADH‐ferricyanide reductase activities. Alkaline phosphatase (inhibitor of rabbit P450 reductase) stimulated NADPH‐cytochrome c reductase activity seven fold but had less effect on NADH‐reductase activities. AADP inhibited nitrofurantoin‐ and menadione‐stimulated KMBA oxidation by 45 and 17%, respectively, indicating the involvement of P450 reductase at least in the former. In contrast, ellipticine had relatively little effect, possibly because, unlike cytochrome c, the smaller xenobiotic molecules can access the hydrophilic binding site of P450 reductase. Alkaline phosphatase stimulated NAD(P)H‐dependent basal and xenobiotic‐stimulated KMBA oxidation, showing general consistency with the results for reductase activities. Overall, the studies indicate both similarities (ellipticine, AADP) and differences (alkaline phosphatase) between the flounder and rat hepatic microsomal enzyme systems.
Autoprotection: Stimulated tissue repair permits recovery from injury
Authors: Mehendale Harihara M. , Thakore Kashyap N. , Rao C. Vaman 
Published: October 2006

AbstractAutoprotection is a phenomenon whereby prior exposure to a small dose of a chemical results in protection against a subsequently administered lethal dose of the same compound. While CCl4 autoprotection has been studied the most, it has also been demonstrated for other chemicals. Recent studies indicate that the prevailing concept of decreased bioactivation of the normally lethal dose of CCl4 owing to decreased hepatic microsomal cytochrome P‐450Abbreviations used: CD, chlordecone; cyt. P‐450, cytochromes P‐450; M, mirex; N, normal diet; PB, phenobarbital.
content can not be supported by direct end points of liver injury such as necrosis. These findings suggest a pivotal role for hepatocellular division and tissue healing processes stimulated by the protective dose in the mechanism of autoprotection. Augmentation of hepatocellular regeneration and tissue repair, stimulated by the protective dose, appears to permit timely recovery and restoration of hepatic structure and function. In the absence of the protective dose, hepatocellular division is substantially deficient and it occurs too late to tip the delicate balance between recovery from injury and progression of massive injury in favor of recovery. Abolition of autoprotection by colchicine antimitosis, under conditions where metabolism and disposition of CCl4 are not altered, is supportive of this concept. Selective colchicine antimitotic suppression of the early phase of hepatocellular division and tissue repair induced by a low dose of CCl4 results in progression of toxic liver injury, leading to hepatic failure and mortality. Studies have shown that pretreatment with phenobarbital results in postponed low‐dose CCl4‐stimulated cell division by 24 hours, which accordingly postpones the optimal autoprotection. These findings provide discrete evidence to suggest that the protective dose‐stimulated hepatocellular division and tissue repair underlies the mechanism of autoprotection. These new insights reveal that in contrast to the widely held concept, the ultimate outcome of toxic injury is determined by whether a prompt stimulation of sustainable tissue repair can occur rather than by the magnitude of the injury inflicted by a toxic chemical.
Phospholipase A2 activation in cultured mouse hepatocytes exposed to tumor necrosis factor‐α
Authors: Adamson Gregory M. , Carlson Timothy J. , Billings Ruth E. 
Published: October 2006

AbstractHigh concentrations of tumor necrosis factor α (TNFα) are cytotoxic to cultured hepatocytes. Impairment of energy metabolism and generation of an intracellular oxidant stress are important events in the pathogenesis of this toxicity (6). In the present study, we have examined the role of phospholipase A2 activation in TNFα‐in‐duced toxicity in mouse hepatocytes, since it has been reported to play a key role in TNFα cytolytic activity in other cell types. Recombinant murine TNFα (0.1 μg/mL) caused a dose‐dependent increase in PLA2 activity in cultured mouse hepatocytes. The increase in PLA2 activity was observed after only 0.5 hour of exposure (152 ± 10% of control), and continued to increased over the first 4 hours of exposure (292 ± 32%). However, TNFα‐induced GSSG efflux and ATP depletion did not occur until after 2 hours of exposure. Furthermore, a small level of cytotoxicity was observed after a 24 hour incubation period. Putative PLA2 inhibitors, chlorpromazine (CPZ) and 4‐bromophenacyl bromide (BPB), both prevented the TNFα‐induced increase in PLA2 activity. They also reduced ATP depletion, GSSG efflux, and cytotoxicity. The PLA2 inhibitor, manoalide (a natural marine product), completely prevented PLA2 activation and cytotoxicity induced by TNFα. Pretreatment of hepatocytes with cycloheximide, to inhibit protein synthesis, increased TNFα‐induced cytotoxicity. Cycloheximide pretreatment also potentiated PLA2 activation, ATP depletion, and GSSG efflux. CPZ and BPB both reduced the extent of PLA2 activation, ATP depletion, GSSG formation, and cytotoxicity in the cycloheximide pretreated cells exposed to TNFα. Taken together, these results demonstrate that TNFα activates PLA2 which occurs prior to other deleterious events in hepatocytes, and that inhibition of PLA2 activity reduces cell injury by TNFα. This suggests that PLA2 activation may lead to impairment of energy metabolism, an oxidant stress, and cytotoxicity in cells exposed to TNFα. Additionally, protein synthesis inhibition potentiates TNFα induction of PLA2 and toxicity, suggesting that there is a protein‐synthesis‐dependent protective mechanism in hepatocytes which ameliorates the effects induced by PLA2. These findings provide strong evidence that PLA2 activation plays an important role in the pathogenesis of toxicity induced by TNFα in cultured mouse hepatocytes.
Hepatic cytochrome P450 2B induction by ethyl/ phenyl‐substituted congeners of phenobarbital in the B6C3F1 mouse
Authors: Nims Raymond W. , Lubet Ronald A. , Diwan Bhalchandra A. , Mellini Donna W. , Utermahlen William E. , Thomas Paul E. 
Published: October 2006

AbstractThe abilities of structural congeners of phenobarbital to induce immunoreactive hepatic cytochrome P450 2B (CYP2B) protein and associated catalytic activity (benzyloxyresorufin O‐dealkylation) in the male B6C3F1 mouse were examined. Interspecies differences in inducing ability were examined through comparison of the results with induction data obtained previously with the male F344/NCr rat. The congeners were administered in the diet for 2 weeks at concentrations equimolar to 500 ppm of the prototype CYP2B inducer, phenobarbital. Of the series of compounds tested, phenobarbital was the most effective inducer of benzyloxyresorufin O,‐dealkylation and immunoreactive CYP2B protein, with 2‐ethyl‐2‐phenylsuccinimide, 5‐ethyl‐5‐phenylhydantoin, primidone, and glutethimide being only 19–42% as effective. 5‐Ethyl‐5‐phenyloxazolidinedione and the ring‐opened and decarboxylated congeners, N‐(2‐ethyl‐2‐phenylacetyl)urea and 2‐ethyl‐2‐phenyl‐malonamide, displayed minimal induction of these catalytic activities. Dose‐response experiments performed with 5‐ethyl‐5‐phenylhydantoin indicated that the intrinsic CYP2B‐inducing activity of this congener was as great as that of phenobarbital in the mouse, although a fourfold greater dietary concentration of this hydantoin (2000 ppm) was required to elicit a response equivalent to that caused by 500 ppm phenobarbital. When extent of induction was related to serum total xenobiotic concentration rather than to administered dietary concentration, the potencies of the two congeners were determined to be more similar (58 vs. ≥78 μ M for phenobarbital and 5‐ethyl‐5‐phenylhydantoin, respectively).
N‐Acetyl‐l‐cysteine abolishes the bromoethylamine‐induced choline incorporation into renal papillary tissue
Authors: Thielemann L. E. , Rodrigo R. A. , Oberhauser E. W. , Rosenblut G. , Videla L. A. 
Published: October 2006

AbstractThe role of regenerative processes in the protective effect of N‐acetyl‐L‐cysteine (NAC) against bromoethylamine‐induced renal papillary necrosis was assessed in rats given bromoethylamine (BEA) (1.2 mmol/kg), N‐acetylcysteine (6 mmol/kg), or N‐acetylcysteine plus BEA. Renal papillary slices were dissected after 15 hours of treatment, and 14C‐choline incorporation into total phospholipid, lysophosphatidylcholine, sphingomyelin, and phosphatidylcholine was measured. Bromoethylamine elicited an increase in the incorporation of 14C‐choline into choline‐containing phospholipid, an effect that was abolished when N‐acetylcysteine was administered prior to bromoethylamine. These studies indicate that the defensive mechanism of N‐acetylcysteine against bromoethylamine‐induced renal papillary necrosis is not related to regenerative processes and that N‐acetylcysteine abolishes the bromoethylamine‐induced choline incorporation into papillary phospholipid. © 1996 John Wiley & Sons, Inc.
Morphological specializations of baleen whales associated with hydrodynamic performance and ecological niche
Authors: Woodward Becky L. , Winn Jeremy P. , Fish Frank E. 
Published: October 2006

AbstractFeeding behavior, prey type, and habitat appear to be associated with the morphological design of body, fluke, and flippers in baleen whales. Morphometric data from whaling records and recent stranding events were compiled, and morphometric parameters describing the body length, and fluke and flipper dimensions for an “average” blue whale Balaenoptera musculus, humpback whale Megaptera novaeangliae, gray whale Eschrichtius robustus, and right whale Eubalaena glacialis were determined. Body mass, body volume, body surface area, and fluke and flipper surface areas were estimated. The resultant morphological configurations lent themselves to the following classifications based on hydrodynamic principles: fast cruiser, slow cruiser, fast maneuverer, and slow maneuverer. Blue whales have highly streamlined bodies with small, high aspect ratio flippers and flukes for fast efficient cruising in the open ocean. On the other hand, the rotund right whale has large, high aspect ratio flukes for efficient slow speed cruising that is optimal for their continuous filter feeding technique. Humpbacks have large, high aspect ratio flippers and a large, low aspect ratio tail for quick acceleration and high‐speed maneuvering which would help them catch their elusive prey, while gray whales have large, low aspect ratio flippers and flukes for enhanced low‐speed maneuvering in complex coastal water habitats. J. Morphol., 2006. © 2006 Wiley‐Liss, Inc.
Skeletal elements within teleost eyes and a discussion of their homology
Authors: Franz‐Odendaal Tamara A. , Hall Brian K. 
Published: October 2006

AbstractScleral ossicles and scleral cartilages form part of the craniofacial skeleton of many vertebrates. Some vertebrates, including all birds and most reptiles, but excluding most mammals, have scleral cartilages as well as scleral ossicles supporting their eyes. The teleost equivalent of these elements has received little attention in the literature. From radiographic and whole‐mount analyses of over 400 individuals from 376 teleost species, we conclude that the teleost scleral skeletal elements (ossicles and cartilage) differ significantly from those of reptiles (including birds). Scleral ossicles in teleosts have different developmental origins, different positions within the eyeball, and different relationships with the scleral cartilaginous element than those in reptiles. From whole‐mount staining of a growth series of four species of teleost (Danio rerio, Salmo salar, Esox lucius,andAlosa pseudoharengus), we interpret the development of these elements and show that they arise from within an Alcian blue‐staining cartilaginous ring that develops around the eye earlier in development. We present possible scenarios on the evolution of these scleral skeletal elements from a common gnathostome ancestor, and consider that teleost scleral skeletal elements may not be homologous to those in reptiles. Our study indicates that homologycannot be assumedfor these elements, despite the fact that they share the same name, scleral ossicles. J. Morphol., 2006. © 2006 Wiley‐Liss, Inc.
Glenohumeral kinematics following total shoulder arthroplasty: A finite element investigation
Authors: Hopkins Andrew R. , Hansen Ulrich N. , Amis Andrew A. , Taylor Mark , Emery Roger J. 
Published: October 2006

AbstractThe osseous geometry of the glenohumeral joint is naturally nonconforming and minimally constrained, and the joint's stability is maintained by action of the rotator cuff muscles. Damage to these muscles is often associated with joint degeneration, and a variety of glenoid prostheses have been developed to impart varying degrees of stability postoperatively. The issues of conformity and constraint within the artificial shoulder have been addressed through in vivo and in vitro studies, although few computational models have been presented. The current investigation presents the results of three‐dimensional finite element analyses of the total shoulder joint and the effects of design parameters upon glenohumeral interaction. Conformity was shown not to influence the loads required to destabilize the joint, although it was the principal factor determining the magnitude of humeral head translation. Constraint was found to correlate linearly with the forces required to dislocate the humeral head, with higher constraint leading to slightly greater humeral migration at the point of joint instability. The model predicts that patients with a dysfunctional supraspinatus would experience frequent eccentric loading of the glenoid, especially in the superior direction, which would likely lead to increased fixation stresses, and hence, a greater chance of loosening. For candidates with an intact rotator cuff, the models developed in this study predict that angular constraints of at least 14° and 6.5° in the superoinferior and anteroposterior axes are required to provide stable unloaded abduction of the humerus, with larger constraints of 18° and 10° necessitated by a dysfunctional supraspinatus. The tools developed during this study can be used to determine the capacity for different implant designs to provide resistance to excessive glenohumeral translations and reduce the potential for instability of the joint, allowing surgeons to optimize postoperative functional gains on a patient by patient basis. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:108–115, 2007
Apparent ileal digestibility of amino acids in feed ingredients determined with broilers and layers
Authors: Huang Kim H , Ravindran Velmurugu , Li Xiuhua , Ravindran Ganesharanee , Bryden Wayne L 
Published: October 2006

AbstractThe apparent ileal digestibility of amino acids in eight feed ingredients were determined using broilers and layers. The ingredients included three cereals (wheat, sorghum and maize), one cereal by‐product (wheat middlings), three oilseed meals (canola, cottonseed and soybean meals) and one animal protein meal (meat and bone meal). Dietary protein in the assay diets was supplied solely by the test ingredient. All diets contained 20 g kg−1 acid‐insoluble ash as an indigestible marker, and each diet was offered ad libitum in mash form to five replicate pens of 42‐day‐old broilers and 60‐week‐old layers. The digestibility coefficients of most amino acids for wheat and sorghum were similar (P > 0.05) in broilers and layers. The digestibility of most amino acids for maize was higher (P < 0.05) in broilers compared to those in layers. The digestibility of individual amino acid for wheat middlings was higher (P < 0.05) in layers than in broilers. In general, the digestibility of amino acids for cottonseed meal, soybean meal, and meat and bone meal were similar (P > 0.05) between broilers and layers. The influence of class of bird on digestibility in canola meal was variable. The digestibility of threonine, valine, isoleucine, leucine, phenylalanine, glutamic acid and alanine were higher (P < 0.05), and those of methionine, histidine and lysine were lower (P < 0.05) in broilers compared to layers. These results suggest that the practice of using amino acid digestibility values generated with broilers for layers may not be appropriate for all feed ingredients. Copyright © 2006 Society of Chemical Industry
Search history tools for user support in information retrieval systems: Evaluation results from an iterative, user‐centered process
Authors: Kaur Manpreet , Komlodi Anita , Komlodi Tamas , Win Khine 
Published: October 2006

AbstractThis poster describes the results of usability evaluation of a novel search history tool and a set of iteratively developed user interface design guidelines for search histories that support execution of complex tasks by information seekers. Search histories have a great potential in search support. To support the information seekers' needs, an integrated search history tool was developed based on the results of an extensive user study of attorneys and law librarians' memory use in searching and is described in the poster. This tool has been iteratively refined through a cooperative design process and two cycles of usability evaluations in legal and medical domains. An integrated and interactive search history display is proposed with user annotations and marking. The history displays details of search steps and can be selectively edited by users. An additional notepad area affords flexible results collection and early integration via user annotations and notes. The evaluation of the search history tool shows great promise in providing improved search history support for information seekers for complex tasks. The results of the evaluation validated the user interface design guidelines for search histories and will be described in this poster. It is hoped that these results will enable the designers of IR systems to better integrate historical information into their systems and provide improved support for users.
Selecting and measuring task characteristics as independent variables
Authors: Kim Soojung , Soergel Dagobert 
Published: October 2006

AbstractThis paper presents a first step toward a systematic framework for organizing numerous task characteristics or variables that are important in studying the effect of task on information behavior. The paper discusses issues related to selecting, operationalizing, and measuring task characteristics to be used as independent variables. It assembles a list of task characteristics and task classifications based on the characteristics to identify potential independent variables. The study also addresses research design issues to study the effect of task characteristics on information seeking and task performance. Finally, it summarizes findings about relationship between particular task characteristics and information seeking to help researchers form new hypotheses.