bluuebunny/crossref_metadata_2025 huggingface dataset:
Interannual variation of larval fish assemblages in the Gulf of Cádiz (SW Iberian Peninsula) in relation to summer oceanographic conditions
Authors: Mafalda Júnior Paulo , Rubín Juan Perez de
Published: April 2006

Two ichthyoplankton surveys were conducted during July 1994 and July 1995 in the Gulf of Cádiz with the aim of describing composition, abundance, distribution patterns and interannual variations of larval fish assemblages. Interannual differences were found in this study. In 1994, higher salinities were observed at external sites, though in 1995, higher values were observed at intermediate sites. The upper water column was warmer in 1994 and had less fish larvae density. During 1994, Sardinella aurita and Engraulis encrasicolus were abundant but spatial location was opposite. In 1995, abundance of both species was very different, but with similar spatial pattern. Cluster analysis revealed well-defined groups of stations and assemblages of larvae, primarily related to bathymetry. The "inshore assemblage" occupied the shallow coast area; its characteristics species being closely related to the estuarine system, mainly comprising Engraulis encrasicolus and Gobiidae. The "shelf assemblage" occupied the continental shelf and its characteristics species consisted of larvae whose adults inhabited the shelf province and spawn in the same zone, like Sardinella aurita and Trachurus spp. Interannual variations in composition and extension of the subgroups could be attributed to the main circulation patterns, continental water discharge and spawning strategies of fishes.
Testis and vas deferens morphology of the red-clawed mangrove tree crab (Goniopsis cruentata) (Latreille, 1803)
Authors: Garcia Tatiane Martins , Silva José Roberto Feitosa
Published: April 2006

The present study describes the structure of the testes and vas deferens of the red-clawed mangrove tree crab, Goniopsis cruentata. Testes and vas deferens were fixed with cold Bouin's solution and submitted to histological routine examinations. Light microscopy showed the testis to be divided into three regions: anterior, containing the germinal zone; intermediary, including the collecting duct; and posterior. The vas deferens, which was continuous with the testes, could be divided into two regions: one corresponding to the expansions and another lined by cubical epithelium, collagenous fibers and a circular layer of muscle cells and containing the androgenic gland. Spermatophores were observed in both vas deferens regions suggesting that they participated in the maturation of the spermatozoids preparing the male functionally for fertilization.
Detrimental actions of metabolic syndrome risk factor, homocysteine, on pancreatic β-cell glucose metabolism and insulin secretion
Authors: Patterson S , Flatt P R , Brennan L , Newsholme P , McClenaghan N H
Published: April 2006

Elevated plasma homocysteine has been reported in individuals with diseases of the metabolic syndrome including vascular disease and insulin resistance. As homocysteine exerts detrimental effects on endothelial and neuronal cells, this study investigated effects of acute homocysteine exposure on β-cell function and insulin secretion using clonal BRIN-BD11 β-cells. Acute insulin release studies in the presence of various test reagents were performed using monolayers of BRIN-BD11 cells and samples assayed by insulin radioimmunoassay. Cellular glucose metabolism was assessed by nuclear magnetic resonance (NMR) analysis following 60-min exposure of BRIN-BD11 cell monolayers to glucose in either the absence or presence of homocysteine. Homocysteine dose-dependently inhibited insulin release at moderate and stimulatory glucose concentrations. This inhibitory effect was reversible at all but the highest concentration of homocysteine. 13C-glucose NMR demonstrated decreased labelling of glutamate from glucose at positions C2, C3 and C4, indicating that the tricarboxylic acid (TCA) cycle-dependent glucose metabolism was reduced in the presence of homocysteine. Homocysteine also dose-dependently inhibited insulinotropic responses to a range of glucose-dependent secretagogues including nutrients (alanine, arginine, 2-ketoisocaproate), hormones (glucagon-like peptide-1 (7–36)amide, gastric inhibitory polypeptide and cholecystokinin-8), neurotransmitter (carbachol), drug (tolbutamide) as well as a depolarising concentration of KCl or elevated Ca2+. Insulin secretion induced by activation of adenylate cyclase and protein kinase C pathways with forskolin and phorbol 12-myristate 13-acetate were also inhibited by homocysteine. These effects were not associated with any adverse action on cellular insulin content or cell viability, and there was no increase in apoptosis/necrosis following exposure to homocysteine. These data indicate that homocysteine impairs insulin secretion through alterations in β-cell glucose metabolism and generation of key stimulus-secretion coupling factors. The participation of homocysteine in possible β-cell demise merits further investigation.
Skeletal muscle glucose transporter protein responses to antenatal glucocorticoids in the ovine fetus
Authors: Gray Susan , Stonestreet Barbara S , Thamotharan Shanthie , Sadowska Grazyna B , Daood Molly , Watchko Jon , Devaskar Sherin U
Published: April 2006

We investigated the effects of maternal antenatal dexamethasone (Dex) treatment given as a single course (4 doses) or multiple courses (20 doses) on fetal skeletal muscle glucose transporter (GLUT) protein concentrations at 70% of gestation (106 to 107 days with term being 145 to 150 days) in the ovine fetus. Antenatal corticosteroid administration was associated with a decrease in endogenous fetal plasma cortisol concentrations (P < 0.05), fetal hyperglycemia (P < 0.02) and hyperinsulinemia (P < 0.05). These metabolic/hormonal changes were associated with a decrease in fetal body weight (P < 0.05) in the multiple course Dex group compared with the multiple course placebo group. These perturbations were associated with an increase in fetal skeletal muscle GLUT 1 concentrations that mediate basal glucose transport in the extensor digitorum lateralis and extensor digitorum longus muscles (P < 0.05) 18 h after the last dose of Dex was given in the single course group. However, in the multiple course Dex group, a small increase in GLUT 1 was observed only in the biceps femoris. In contrast, both single and multiple courses of antenatal Dex were associated with an increase in the extensor digitorum lateralis and biceps femoris muscle GLUT 4 (insulin-responsive) concentrations (P < 0.05). We conclude that antenatal corticosteroids perturb fetal glucose/insulin homeostasis, which is associated with increases in fetal skeletal muscle glucose transporters to compensate for and attenuate the associated catabolic fetal state. These changes consist of an increase in proteins that mediate basal glucose transport (GLUT 1) to meet immediate energy requirements of the fetal skeletal muscle with an increase in basal insulin sensitivity (GLUT 4) to compensate for the Dex-induced catabolic state after exposure to multiple courses of Dex.
Prolactin inhibits the apoptosis of chondrocytes induced by serum starvation
Authors: Zermeño C , Guzmán-Morales J , Macotela Y , Nava G , López-Barrera F , Kouri J B , Lavalle C , de la Escalera G Martínez , Clapp C
Published: April 2006

The apoptosis of chondrocytes plays an important role in endochondral bone formation and in cartilage degradation during aging and disease. Prolactin (PRL) is produced in chondrocytes and is known to promote the survival of various cell types. Here we show that articular chondrocytes from rat postpubescent and adult cartilage express the long form of the PRL receptor as revealed by immunohistochemistry of cartilage sections and by RT-PCR and Western blot analyses of the isolated chondrocytes. Furthermore, we demonstrate that PRL inhibits the apoptosis of these same chondrocytes cultured in low-serum. Chondrocyte apoptosis was measured by hypodiploid DNA content determined by flow cytometry and by DNA fragmentation evaluated by the ELISA and the TUNEL methods. The anti-apoptotic effect of PRL was dose-dependent and was prevented by heat inactivation. These data demonstrate that PRL can act as a survival factor for chondrocytes and that it has potential preventive and therapeutic value in arthropathies characterized by cartilage degradation.
Influence of steam curing on hardened properties of recycled aggregate concrete
Authors: Poon, C.-S. , Kou S. C. , Chan D.
Published: April 2006

The effects of steam curing on the hardened properties of recycled aggregate concrete were investigated. In this study, two series of concrete mixtures with water/cement ratios of 0·55 and 0·45 were prepared. Recycled aggregates were used as 0, 20, 50 and 100% by volume replacements of natural coarse aggregate in the concrete mixtures. The concrete specimens underwent standard water-curing and steam-curing regimes. The test results showed that the strength of concrete decreased as the recycled aggregate content increased. An initial steam-curing regime increased the one-day strength of the concrete, but the corresponding 28- and 90-day strengths decreased. Furthermore, steam curing reduced the static modulus of elasticity of concrete compared with that of the water cured concrete. However, the negative effect of steam curing diminished as the recycled aggregate content increased. Moreover, steam curing decreased the drying shrinkage and increased the resistance against chloride ion penetration of the recycled aggregate concrete. The results demonstrate that one of the practical ways to utilise a higher percentage of recycled aggregates in concrete is ‘precasting’ with an initial steam curing stage immediately after casting.
Mechanical properties of concrete containing recycled asphalt pavements
Authors: Huang B. , Shu X. , Burdette E. G.
Published: April 2006

Recycled asphalt pavement (RAP) is the removed and/or reprocessed pavement material containing asphalt and aggregate. The use of RAP in asphalt pavement has become common practice in the construction of new, and reconstruction of old, hot-mix asphalt (HMA) pavements. However, little research has been done to examine the potential of incorporating RAP into Portland cement concrete (PCC) to replace virgin aggregate. In a previous study by the first two of the current authors, laboratory-prepared RAP was used to investigate the potential use of RAP in PCC. The present study focused on the evaluation of mechanical properties of PCC made with real RAP materials through laboratory experiments. Two types of RAP materials (coarse and fine RAP) were used to replace an equal amount of virgin coarse and/or fine aggregate. Silica fume and high-range water-reducing agent (HRWRA) were also added into concrete mixtures to minimise the strength loss resulting from the incorporation of RAP. A total of 17 concrete batches were cast and evaluated for compressive and split tensile strengths, static compressive modulus of elasticity and toughness index. Test results indicated that there was a systematic reduction in the strengths and elastic modulus as well as an increase in the toughness index with the increase in RAP content. While the addition of HRWRA into the matrix improved the mechanical properties of concretes containing RAP, addition of silica fume did not.
Effect of geopolymer cement on microstructure, compressive strength and sulphuric acid resistance of concrete
Authors: Hewayde E. , Nehdi M. , Allouche E. , Nakhla G.
Published: April 2006

The effect of geopolymer cement on the compressive strength and resistance to sulphuric acid of concrete made with type 10 and type 50E cements was studied. Hydration products and microstructure of various concrete mixtures incorporating geopolymer cement were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmitted light microscopy in order to identify the mechanisms underlying the effects of the geopolymer cement on concrete properties. Experimental results indicate that using geopolymer cement as partial replacement for ordinary Portland cement (OPC) effectively improved both the compressive strength and resistance to sulphuric acid. Replacement of 50% OPC by geopolymer cement increased the 28-day compressive strength by about 50% and reduced the mass loss of concrete specimens subjected to eight weeks of immersion in sulphuric acid solutions with pH of 0·3 and 0·6 by 42% and 30%, respectively. The effect of geopolymer cement on the compressive strength and sulphuric acid resistance of concrete made with type 50E cement was less significant than that for concrete made with type 10 cement. Results of XRD, SEM and light microscopy indicate that improvements in compressive strength and sulphuric acid resistance of the geopolymer modified concrete can be mainly attributed to the formation of new hydration products such as calcium–magnesium–aluminium-oxide silicates. A direct relationship between the ability of geopolymer modified concrete specimens to resist sulphuric acid and their normal 28-day compressive strength was found, but varied with the binder used.
Ink‐jet printing: The route to production of full‐color P‐OLED displays
Authors: Bale M. , Carter J. C. , Creighton C. J. , Gregory H. J. , Lyon P. H. , Ng P. , Webb L. , Wehrum A.
Published: April 2006

Abstract— Ink‐jet‐printing technology for displays has been making rapid progress and is now nearing production. This paper will go through the developments that have been carried out at CDT, Ltd., to achieve this status. The ink‐jet head and machine development that underpin the capability of the RGB printing process to manufacture P‐OLEDs at high speed with high reliability and with the film‐forming properties to achieve the appropriate device performance will be described. The important contribution made by the availability of flexible metrological tools will be discussed.
Nano‐emissive display technology for large‐area HDTV
Authors: Coll B. F. , Dean K. A. , Howard E. , Johnson S. V. , Johnson M. R. , Jaskie J. E.
Published: April 2006

Abstract—Using nano‐emissive display (NED) technology, Motorola labs has successfully developed 5‐in. full‐color display prototypes. Carbon‐nanotube‐based field‐emission displays with a pixel size of 0.726 mm for a 42‐in. HDTV exhibit video image quality comparable to CRT displays and demonstrate a luminance of 350 cd/m2. These novel low‐drive‐voltage NEDs take advantage of selective growth of CNTs to obtain the desired electron‐emission performance while maintaining inexpensive manufacturing due to a simple self‐focusing and self‐regulating planar structure. Improved video image quality and color purity are achieved with very low power consumption and without the need for an expensive focusing grid.
Influence of body size on swimming performance of four species of neonatal natricine snakes acutely exposed to a cholinesterase-inhibiting pesticide
Authors: Hopkins William A. , Winne Christopher T.
Published: April 2006

Locomotor performance is an important fitness-related trait in reptiles because of its potential influence on prey capture and predator avoidance. Because cholinesterase-inhibiting pesticides disrupt neuromuscular signaling, reduction in performance seems to be a logical translation of this biochemical disruption to the organism level. In the present study, we compared the swimming performance of four species of natricine snakes acutely exposed to a formulation of carbaryl to determine whether neonatal body size or skin permeability influences responsiveness. Exposure to high concentrations of carbaryl (2.5–5.0 mg/L) resulted in reduced swimming performance in all four species of snakes, and species responded similarly to the pesticide once body size was accounted for allometrically. Using traditional methods in physiological ecology to estimate skin permeability (a parameter that influences the dose of contaminant absorbed), we found that water flux across the integument also scaled allometrically with body surface area and, therefore, was similar among species after controlling for this relationship. We suggest that future studies examining the effects of repeated low-dose exposure to cholinesterase inhibitors on performance parameters will be useful in assessing the ecological significance of our findings.
Effects of the organophosphate paraoxon-methyl on survival and reproduction ofDaphnia magna: Importance of exposure duration and recovery
Authors: Duquesne Sabine , Reynaldi Sebastián , Liess Matthias
Published: April 2006

The aim of this study was to determine the influence of exposure duration (1 h, 24 h, continuous) to paraoxon-methyl on the magnitude of lethal and sublethal effects, the shape of the concentration-response relationships and the recovery processes in Daphnia magna. Survival was more severely reduced in the continuous than in the pulse exposure regimes. The lethal concentrations (3d median lethal concentration [LC50] values) were 233, 2.33, and 1.14 μg/L after 1-h, 24-h, and continuous exposure, respectively. The shapes of the concentration-response relationships for survival were significantly different after 1 h of exposure than after 24-h and continuous exposure. Indeed, the slopes of the curves defined by the ratios LC90/LC10 (ratio of 90 and 10% lethal concentrations) were 100, 1.74, and 1.97 for 1-h, 24-h, and continuous exposure, respectively. The large difference between 1 h and longer durations of exposure shows that the population is partially affected (10–90%) over a much broader range of concentrations when exposure is short. Negative effects on reproductive outputs occurred mostly at concentrations affecting partly the survival and therefore also over a broad range of concentrations after 1 h of exposure. However, these effects were only transient in the pulse exposure regimes as individual performances recovered. By contrast, reproductive outputs of survivors exposed continuously remained impaired. These results suggest that a refined risk assessment should consider exposure duration because it influences the magnitude of effects and recovery.
Effects of sediment-bound zinc contamination on early life stages of the mummichog (Fundulus heteroclitus L.) in the Christina Watershed, Delaware, USA
Authors: Guy Christopher Paul , Pinkney Alfred Eli , Taylor Malcolm Herbert
Published: April 2006

During the last century, the Christina River, the major estuarine river system in New Castle County (DE, USA), has received loadings of organic and inorganic chemicals, primarily from manufacturing facilities. Among the most abundant chemicals is zinc, which has accumulated in sediments at concentrations as high as 5,440 mg/kg. We studied the possible effects of zinc on early life stages of the mummichog (Fundulus heteroclitus), a resident species in the river and watershed. We conducted three different types of exposures. The first was a 96-h median lethal concentration (LC50) test with larvae exposed to waterborne zinc. The second was a larval exposure with zinc-spiked sediments (obtained from the relatively uncontaminated Magothy River in Anne Arundel County, MD, USA). The third was an embryo–larval exposure with Christina River sediments having a gradient of zinc concentrations. The average 96-h LC50 with newly hatched yolk sac larvae was 970 μg/L. In the larval tests, the average 7- and 21-d LC50s were 1,154 and 1,012 mg/kg, respectively. In the embryo–larval test, no significant difference was found in survival at concentrations between 38.8 and 1,098 mg/kg. However, significant reductions were observed in condition factor at concentrations of 582, 799, and 1,098 mg/kg. We calculated an average no-observed-effects concentration of 579 mg/kg and an average lowest-observed-effects concentration of 849 mg/kg for larval survival. Based on these results, we suggest that zinc in the Christina River may be affecting early life stages of the mummichog.
Alteration of dissolved cadmium and zinc uptake kinetics by metal pre-exposure in the black sea bream (Acanthopagrus schlegeli)
Authors: Zhang Li , Wang Wen-Xiong
Published: April 2006

We first examined the uptake kinetics of Cd and Zn in the juvenile marine black sea bream (Acanthopagrus schlegeli) over a wide range of ambient Cd and Zn concentrations, and the relationships with metal accumulation (uptake rate and amount of nonexchangeable surface binding) were established for different fish tissues. Both Cd and Zn accumulation in the body increased linearly with exposure time after the initial metal surface binding. The dissolved Cd and Zn uptake rate constants were 2.64 and 6.50 L/kg/d, respectively, and the kinetics followed a first-order process. No evidence of biphasic transport was found, in contrast to the situation in freshwater fish. Viscera were the most important sites of metal uptake, and gills were the second most important sites. The black sea breams were then acclimated at different Cd or Zn concentrations from either waterborne or dietary source for one week, and the alteration of metal uptake kinetics or subcellular distribution and metallothionein (MT) induction were further quantified. The Cd body burden was enhanced up to 8.6- and 49-fold after waterborne and dietary Cd pre-exposure, respectively. Cadmium pre-exposure also altered the tissue-specific subcellular Cd distribution and significantly elevated tissue MT levels. In contrast, the black sea breams were able to regulate Zn accumulation, and waterborne or dietary Zn pre-exposure had only weak influences on Zn body burden and redistribution. Both Cd and Zn pre-exposures enhanced the metal uptake rate constants, whereas the nonexchangeable surface bindings were less impacted by these pre-exposures. We demonstrated a positive relationship between the Cd uptake rate and Cd or MT concentration in the fish. Pre-exposure to metals may substantially modify the kinetics of metal uptake.
Contaminated sediment testing with the bivalveMulinia lateralis: Culture refinement for organism availability
Authors: Cripe Geraldine M.
Published: April 2006

Availability of test species for estuarine benthic assessment is limited; therefore, a method was developed by the U.S. Environmental Protection Agency for using the dwarf surf clam (Mulinia lateralis) to identify adverse biological effects of bulk estuarine sediments. A multilaboratory evaluation of the draft method resulted in favorable responses from the participants with respect to general testing and handling of the clam. However, availability of good-quality test organisms was limited. An investigation of culture techniques determined that culture vessel topography dramatically influenced survival, because larvae accumulated in bottom depressions. Conditioning of brood stock was enhanced by algae naturally containing both 20:5n-3 and 22:6n-3 fatty acids. Survival of larvae to metamorphosis at 14 d postspawn was greatly increased by maintenance at a lighting of 734 lux with addition of gradually increasing amounts of Isochyris galbana and Chaetoceros calcitrans. Greater than 50% survival of 600 juveniles to testing size by 14 d postmetamorphosis was accomplished by intermittent delivery of algae 12 times per day in a total of 13 L of seawater. By 21 d postmetamorphosis, an additional 27% achieved testable size. As a result of identification of these culture parameters, test bivalves can be readily available to improve predictions of adverse biological effects on benthic communities beyond those presently determined through amphipod exposures.
Alternative approaches can greatly reduce the number of fish used for acute toxicity testing
Authors: Hoekzema Conny C. , Murk Albertinka J. , van de Waart Beppy J. , van der Hoeven Jan C. M. , de Roode Daphne F.
Published: April 2006

Acute toxicity tests with algae, daphnids, and fish are required for the classification and environmental risk assessment of chemicals. The degree of risk is determined by the lowest of these acute toxicity values. Many ecotoxicological programs are seeking to reduce the numbers of fish used in acute toxicity testing. The acute threshold test is a recently proposed strategy that uses, on average, only 10 (instead of 54) fish per chemical. We examined the consequences of reducing the number of fish used in toxicity testing on the ultimate outcome of risk assessments. We evaluated toxicity data sets for 507 compounds, including agrochemicals, industrial chemicals, and pharmaceuticals from our internal database. Theoretical applications of the acute threshold test gave similar results to those obtained with the standard fish median lethal concentration (LC50) test but required only 12% as many fish (3,195 instead of 27,324 fish used for all compounds in the database). In 188 (90%) of the 208 cases for which a complete data set was available, the median effect concentration for algae or daphnids was lower than the LC50 for fish. These results show that replacement of the standard fish LC50 test by the acute threshold test would greatly reduce the number of fish needed for acute ecotoxicity testing without any loss of reliability.
Population growth ofDaphnia magnaunder multiple stress conditions: Joint effects of temperature, food, and cadmium
Authors: Heugens Evelyn H. W. , Tokkie Lonneke T. B. , Kraak Michiel H. S. , Hendriks A. Jan , van Straalen Nico M. , Admiraal Wim
Published: April 2006

Aquatic organisms in the field often are exposed to combinations of stress factors of variousorigins. Little is known of the interaction between different types of stressors; hence, the predictability of their joint effects is low. Therefore, the present study analyzed the joint effects of temperature, food, and cadmium on the population growth rate of the water flea Daphnia magna. The results revealed that temperature, food, and cadmium, as well as their interactions, were important factors that influenced life-history parameters and, as a consequence, the population growth rate of D. magna. In general, population growth rate increased at high temperature and food level but decreased when cadmium was present. The positive effect of temperature on population growth rate was smallest at limiting food levels. Negative effects of cadmium on the growth rate were enhanced at elevated temperatures, whereas high food levels protected the daphnids from adverse effects of cadmium. To avoid over- or underestimation regarding the toxicity of substances to field populations, results of standard toxicity tests should be applied in a location-specific way.
Comparing median lethal concentration values using confidence interval overlap or ratio tests
Authors: Wheeler Matthew W , Park Robert M. , Bailer A. John
Published: April 2006

Experimenters in toxicology often compare the concentration-response relationship between two distinct populations using the median lethal concentration (LC50). This comparison is sometimes done by calculating the 95% confidence interval for the LC50 for each population, concluding that no significant difference exists if the two confidence intervals overlap. A more appropriate test compares the ratio of the LC50s to 1 or the log(LC50 ratio) to 0. In this ratio test, we conclude that no difference exists in LC50s if the confidence interval for the ratio of the LC50s contains 1 or the confidence interval for the log(LC50 ratio) contains 0. A Monte Carlo simulation study was conducted to compare the confidence interval overlap test to the ratio test. The confidence interval overlap test performs substantially below the nominal α = 0.05 level, closer to p = 0.005; therefore, it has considerably less power for detecting true differences compared to the ratio test. The ratio-based method exhibited better type I error rates and superior power properties in comparison to the confidence interval overlap test. Thus, a ratio-based statistical procedure is preferred to using simple overlap of two independently derived confidence intervals.
Anaerobic transformation of a technical brominated diphenyl ether mixture by super-reduced vitamin B12 and dicyanocobinamide
Authors: Gaul Simon , von der Recke Roland , Tomy Gregg , Vetter Walter
Published: April 2006

The anaerobic transformation of the technical octabromo diphenyl ether mixture, DE-79, was investigated by incubation with two super-reduced corrinoids, dicyanocobinamide and cyanocobalamin (vitamin B12). The transformation produced 33 brominated diphenyl ethers (BDEs), 23 of which could be assigned to known structures. Within 1 d, the hepta- to nona-BDEs in DE-79 were almost quantitatively transformed with dicyanocobinamide to lower-brominated homologs. Along with the decrease of high-brominated congeners, concentrations of some tetra- to hexabromo congeners initially increased, followed by a decreasing or constant concentration during longer incubations. Super-reduced cyanocobalamin also was able to transform BDE congeners of DE-79. Whereas the transformation rates of hepta- to nona-BDEs of DE-79 by both corrinoids were comparable, tri- to hexa-BDEs were susceptible to further transformation by super-reduced cyanocobalamin. Incubation of DE-79 with either corrinoid produced significant amounts of BDE 49. Because this congener is found in small quantities in both penta- and octabromo technical BDE mixtures, it may be a suitable indicator for reductive debromination of higher-brominated BDEs. Isolated BDE 196 was incubated as well with super-reduced dicyanocobalamine. After 1 d, 13 BDEs could be detected, with BDE 153, BDE 100, and BDE 99 dominating. After 7 d, only tetra-BDEs or lower-brominated BDEs were detectable. It could be shown that reductive debromination by super-reduced corrinoids is a possible source for lower-brominated BDEs (i.e., BDE 47, BDE 99, BDE 153, and BDE 154). The patterns observed with our bench-scale study design demonstrate that anaerobic transformation in the presence of reducing agents can help to explain the occurrence of environmentally relevant BDE congeners (e.g., BDE 47, BDE 99, and BDE 153).
Chemical characterization of brominated flame retardants and identification of structurally representative compounds
Authors: Andersson Patrik L. , Öberg Kjell , Örn Ulrika
Published: April 2006

Three training sets were selected, each consisting of 10 structurally diverse compounds representative of brominated flame retardants (BFRs) that are either in use or have been used. Just three compounds account for nearly all the total production volume of BFRs. In the present study, however, the physicochemical characteristics of a far more structurally diverse set of 65 BFRs was explored using 15 molecular descriptors (including log P, constitutional counts, and semiempirical quantum mechanical parameters) and principal component analysis (PCA). The PCA generated an overview of the structural variation among BFRs, and certain compounds with unique physicochemical properties and specific clusters of compounds with distinct properties were identified. The training-set compounds were selected by applying the condensed information obtained from the PCA and statistical experimental design. The three training sets, which were designated as optimal, practical, and alternative, were selected either to maximize the structural variation (optimal) or to combine structural variation with practical advantages, such as ease of experimental handling and commercial availability (practical and alternative). Inclusion of the suggested compounds in assessments of the persistence, bioaccumulation, and toxicity properties of BFRs and related programs should help to increase our understanding of the effects and environmental fate of these compounds.
Development of a solvent-free, solid-phase in vitro bioassay using vertebrate cells
Authors: Bopp Stephanie K. , Bols Niels C. , Schirmer Kristin
Published: April 2006

Miniaturized bioassays offer many advantages in exploring the toxic potential of chemicals, including small sample volumes and compatibility with high-throughput screening. One problem common to miniaturized systems, however, is the loss of test chemicals because of sorption. The idea of the current study was to use the sorption phenomenon in a positive way. It was found that contaminants sorbed to the growth surface in wells of tissue-culture plates or to the surface of selected sorbent bead materials are available to vertebrate cells growing in direct contact with the contaminant-coated surface. The use of beads provided more flexibility with regard to surface area, materials, and assay format. Biosilon, a bead cell-culture carrier made of polystyrene, was found to be most suitable. It supported cell adherence and allowed the detection of reproducible dose-response curves of an increase in cytochrome CYP1A enzyme activity by sorbed polycyclic aromatic hydrocarbons in the rainbow trout (Oncorhynchus mykiss) liver cell line, RTL-W1. The resulting bead assay provides a miniaturized, solvent-free exposure system. Potential future applications include the coupling to environmental sampling, in which the bead material is used as solid receiving phase before serving as a surface for vertebrate cells to attach and respond.
Cytotoxicity and aryl hydrocarbon receptor-mediated activity of N-heterocyclic polycyclic aromatic hydrocarbons: Structure-activity relationships
Authors: Sovadinová Iva , Bláha Luděk , Janošek Jaroslav , Hilscherová Klára , Giesy John P. , Jones Paul D. , Holoubek Ivan
Published: April 2006

Toxic effects of many persistent organic pollutants (e.g., polychlorinated biphenyls or polychlorinated dibenzo-p-dioxins and furans) are mediated via the aryl hydrocarbon receptor (AhR). Although polycyclic aromatic hydrocarbons (PAHs) and their derivatives also activate AhR, their toxic effects remain to be fully elucidated. In the present study, we used the in vitro H4IIEluc transactivation cell assay to investigate cytotoxicity and potencies to activate AhR by 29 individual PAHs and their N-heterocyclic derivatives (aza-PAHs). The aza-PAHs were found to be significantly more cytotoxic and more potent inducers of AhR than their unsubstituted analogues. Several aza-PAHs, such as dibenz[a,h]acridine or dibenz[a,i]acridine, activated AhR within picomolar concentrations, comparable to the effects of reference 2,3,7,8-tetrachlorodibenzo-p-dioxin. Ellipsoidal volume, molar refractivity, and molecular size were the most important descriptors derived from the modeling of quantitative structure-activity relationships for potencies to activate AhR. Comparable relative toxic potencies (induction equivalency factors) for individual aza-PAHs are derived, and their use for evaluation of complex contaminated samples is discussed.
How quality and quantity of organic matter affect polycyclic aromatic hydrocarbon desorption from Norwegian harbor sediments
Authors: Oen Amy M. P. , Breedveld Gijs D. , Kalaitzidis Stavros , Christanis Kimon , Cornelissen Gerard
Published: April 2006

The desorption behavior of phenanthrene, pyrene, and benzo[a]pyrene was investigated for three Norwegian harbor sediments and their respective particle size fractions using the Tenax desorption method. Rate constants for rapidly, slowly, and very slowly desorbing fractions were on the order of 10−1, 10−2 to 10−4, and 10−4 to 10−6/h, respectively. Relatively small amounts were present in the rapidly desorbing fractions (Frapid: <6% for phenanthrene, 3–19% for pyrene, and 1–12% for benzo[a]pyrene). With the exception of benzo[a]pyrene, these Frapid values were generally lower than median Frapid values obtained from more than 100 literature values for native polycyclic aromatic hydrocarbons (PAHs) (22% for phenanthrene, 29% for pyrene, and 8% for benzo[a]pyrene). To understand which parameters influence PAH desorption, relations between desorption behavior and the sediment characteristics were investigated. A significant positive correlation was found between the extent of slow and very slow desorption and the ratios of black carbon to total organic carbon, as well as the temperature at which 50 and 90%, respectively, of the organic matter was oxidized, as obtained from oxidation-only Rock Eval analysis. Thus, black carbon-bound PAHs probably desorb slowly and very slowly. Furthermore, significant positive correlations between desorption behavior and the average particle size were observed, which could be explained by retarded intraparticle diffusion.
Bicontinuous microemulsions as adsorbents for liquid‐phase separation/purification
Authors: Tricoli V. , Farnesi M. , Nicolella C.
Published: April 2006

Novel concepts of liquid‐phase adsorption at the oil/water interface of a bicontinuous microemulsive phase are presented. These ideas are assessed using a tetradecane/didodecyldimethylammonium bromide/water bicontinuous microemulsion (BME) to adsorb chromate anions from aqueous solution. The adsorption isotherms are investigated as a function of solution ionic strength. Our results show that the BME is an effective adsorbent for removing CrO from solutions with good selectivity over Br− and high enrichment ratio, arising from the large internal surface area of the oil/water interface. An approximate model adsorption isotherm is derived from basic thermodynamic considerations. The proposed model is validated against our experimental data with satisfactory agreement for low chromium content in the BME. Implications of these concepts and results for adsorptive separation of generic contaminant from a liquid phase are discussed in comparison with conventional adsorption processes using solid adsorbents and also with micellar‐enhanced ultrafiltration process. © 2006 American Institute of Chemical Engineers AIChE J, 2006
A model for the spray zone in early‐stage fluidized bed granulation
Authors: Schaafsma S. H. , Vonk P. , Kossen N. W. F. , Hoffmann A. C.
Published: April 2006

The formation of granules in the spray zone of a top‐spray fluid‐bed granulation process using a known and uniform drop‐size is studied experimentally and theoretically. Experimental results indicate a multi‐modal size distribution of spherically‐shaped granules. A model is presented to explain this based on the formation of nuclei, and the rapid coalescence of some of these nuclei with droplets or other nuclei in the spray zone of the bed. The model is based on a Bernoulli process and predicts the number frequency of granules to which n droplets have contributed. The model predictions are validated with experimental results for granule size distribution, and the nucleus residence time in the spray zone required to bring model predictions and experimental results into line is shown to be physically plausible by comparing with PEPT tracking of an agglomerate‐like tracer particle. © 2006 American Institute of Chemical Engineers AIChE J, 2006
High‐risk cutaneous squamous cell carcinoma of the head and neck
Authors: Veness Michael J. , Palme Carsten E. , Morgan Gary J.
Published: April 2006

BACKGROUND

Most patients with cutaneous squamous cell carcinoma (cSCC) of the head and neck (HN) are at low‐risk (< 5%) of developing metastatic SCC to regional lymph nodes. However, patients with unfavorable clinicopathologic factors often are under appreciated by clinicians but remain at higher risk for developing metastatic lymph node disease and dying.

METHODS

Patients were identified who had metastatic cSCC to lymph nodes (parotid and cervical) of the HN and who were treated within the context of a multidisciplinary HN cancer service between 1980 and 2005 at Westmead Hospital (Sydney, Australia). Relevant patient details and data from primary lesions were analyzed and reported.

RESULTS

In total, 266 patients were treated with curative intent. The median patient age was 69 years among 219 males and 47 females. The majority of metastatic lymph nodes (162 of 266 lymph nodes; 61%) were located in the parotid with or without cervical lymph node involvement. The median tumor thickness was 6 mm (range, 0.5–28 mm), and the median tumor size was 15 mm (range, 3–70 mm). Most tumors (65%) that measured ≥5 mm in thickness, and 30% of patients had lesions that measured ≥2 cm in greatest dimension. Recurrent cSCC was present in 15% of patients, and most lesions were located within the lymphatic drainage of the parotid on the temple/forehead (28%), on or around the ear (20%), or on the cheek (12%). Forty‐six percent of patients had moderately or poorly differentiated cSCC, and 5% of patients were immunosuppressed. A minority of patients (27%) did not have an identifiable index lesion.

CONCLUSIONS

Data from this large, prospective data base, in concordance with other series, suggested that a patient with thick cSCC (>4–5 mm) located in proximity to the parotid gland can be considered at high‐risk. Increasing lesion size and recurrence contribute to this risk. Cancer 2006. © 2006 American Cancer Society.
Patterning the heart, a template for human cardiomyocyte development
Authors: Chuva de Sousa Lopes Susana M. , Hassink Rutger J. , Feijen Alie , van Rooijen Marga A. , Doevendans Pieter A. , Tertoolen Leon , Brutel de la Rivière Aart , Mummery Christine L.
Published: April 2006

Although in mice, the dynamics of gene expression during heart development is well characterized, information on humans is scarce due to the limited availability of material. Here, we analyzed the transcriptional distribution of Mlc‐2a, Mlc‐1v, Mlc‐2v, and atrial natriuretic factor (ANF) in human embryonic hearts between 7 and 18 weeks of gestation and in healthy and hypertrophic adult hearts by in situ hybridization and compared expression with that in mice. Strikingly, Mlc‐2a, Mlc‐1v, and ANF, which are essentially chamber‐restricted in mice by mid‐gestation, showed a broader distribution in humans. On the other hand, Mlc‐2v may prove to be an adequate ventricular marker in humans in contrast to mouse. This study emphasizes the importance of careful comparative human–animal analyses during embryonic development and adulthood, as avoiding erroneous extrapolations may be critical to develop new and successful myocardial replacement therapies. Development Dynamics 235:1994–2002, 2006. © 2006 Wiley‐Liss, Inc.
The effect of self‐designed bifunctional RGD‐containing fusion protein on the behavior of human keratinocytes and dermal fibroblasts
Authors: Wang Tzu‐Wei , Wu Hsi‐Chin , Huang Yi‐Chau , Sun Jui‐Sheng , Lin Feng‐Huei
Published: April 2006

In this study, self‐designed bifunctional RGD‐containing fusion protein (BFP) was grafted on the petri dish to evaluate its cytotoxicity and attachment efficiency on primary cultured keratinocytes and dermal fibroblasts. Two lengths of the GRGDS sequences were separately fused to the N‐terminus and C‐terminus of the Trichoderma koningii cellobiohydrolase I gene cellulose‐binding domain, to serve as linking molecule between the cell and the substrate. The grafting procedure was no more labor‐intensive and could be done just in aqueous condition itself. The epidermal keratinocytes and dermal fibroblasts, harvested and separated from human foreskin, were cultured in serum‐free keratinocyte culture medium and DMEM, respectively. The BFP was dissolved in double‐deionized water, and was prepared at different concentrations. The BFP solution was subsequently added into the petri dish for grafting. MTT assay, total DNA measurement, and lactate dehydrogenase analysis were used to evaluate the cell viability, cell proliferation, and cytotoxicity. The immunochemical stain and SEM examination were chosen to make sure that the cultured cells still kept in phenotype. The results showed that the self‐designed BFP was successfully coated on the petri dish to improve the cells' adhesion. The whole coating procedure was just done in aqueous solution without any organic solvent being involved. This method was much simpler than the traditional one, and there was no possibility to damage the immobilized biomolecules. From the results of the study, BFP could enhance attachment of keratinocytes and dermal fibroblasts without losing normal cell morphology and keep keratinocytes on the desired differentiation pathway. We believe that coating BFP on petri dish not only enhanced the keratinocyte attachment but also promoted keratinocytes proliferation. We suggest that the self‐designed BFP has a great potential to apply on surface modification for the tissue‐engineering scaffolds in the future. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Modification of HTPB‐based polyurethane with temperature‐sensitive poly(N‐isopropyl acrylamide) for biomaterial usage
Authors: Yang Jen Ming , Yang Shu Jyuan , Lin Hao Tzu , Chen Jan Kan
Published: April 2006

Hydroxyl‐terminated polybutadiene (HTPB)‐based polyurethane with dimethyol propionic acid (DPA) as chain extender was synthesized by solution polymerization. The HTPB‐based polyurethane was modified by UV radiation with N‐isopropyl acrylamide monomer to get poly(N‐isopropyl acrylamide)‐modified polyurethane (PUDPANIPAAm). The cohesive energy (Ecoh), molar volume (V), solubility parameter (δ), molecular weight (WM), volume per gram (Vg), and the density (1/Vg) of PUDPANIPAAm were calculated by group contribution methods. To evaluate the application of PUDPANIPAAm for wound dressing and transplantation of cell sheet, the measurement of water content, water vapor transmission rate, and gas permeation on the PUDPANIPAAm membrane was evaluated. The biocompatibility of these membranes, cell adhesion, and proliferation assay were conducted in the cell culture. The effect of thermosensitivity of poly(N‐isopropyl acrylamide) on cell detachment was also evaluated in the primary study. The results showed that these PUDPANIPAAm membranes are thermosensitive. The modification of PU with poly(N‐isopropyl acrylamide) reduced the water vapor transmission rate and permeability of gas through PUDPANIPAAm membrane. PUDPANIPAAm membranes could support cell adhesion and growth. Owing to the thermosensitive nature of poly(N‐isopropyl acrylamide), the relative cell numbers detached from PUDPANIPAAm membranes were larger than those detached from the polystyrene dish. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Preparation and Characterization of Nanostructured TiO2/Epoxy Polymeric Films
Authors: Sangermano Marco , Malucelli Giulio , Amerio Ezio , Bongiovanni Roberta , Priola Aldo , Di Gianni Anna , Voit Brigitte , Rizza Giancarlo
Published: April 2006

Summary: Titania‐containing coatings were prepared by cationic photopolymerization of an epoxy resin either by dispersion of preformed TiO2 nanoparticles or by their in‐situ generation through a sol‐gel dual‐cure process. The kinetics of photopolymerization was evaluated by real‐time FT‐IR, studying the effect of the TiO2 concentration. The properties of cured films were investigated, showing an increase of hydrophilicity on the surface of the coatings with increasing TiO2 content. TEM analysis demonstrated that it is possible to achieve a significantly better control of the dispersion of the inorganic particles within the organic matrix by in‐situ generation of TiO2, thus completely avoiding macroscopic phase separation and obtaining homogeneous, transparent coatings.

Bright‐field TEM micrograph for TIP20 dual‐cured film.

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Bright‐field TEM micrograph for TIP20 dual‐cured film.