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Various Concentrations (various + concentration)
Selected AbstractsEvaluation of Various Concentrations of Dietary Protein and Animal Protein for Pond-Raised Channel Catfish Ictalurus punctatus Fed to Satiation or at a Restricted RateJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2000Edwin H. Robinson A factorial experiment was conducted to evaluate effect of dietary protein (28% or 32%), animal protein (0, 3, or 6%), and feeding rate (satiation or >90 kg/ha per d) on production characteristics, processing yield, and body composition of pond-raised channel catfish Ictalurus punctatus. Fingerling channel catfish (average weight: 55 g/fish) were stocked into 60, 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed once daily to satiation or no more than 90 kg/ha per d for 147 d. Fish fed at a rate of >90 kg/ha per d consumed about 85% of the amount of feed consumed by fish fed to satiation. Dietary protein did not affect the total amount of feed fed, amount of feed consumed per fish, weight gain, feed conversion efficiency, or fillet protein. Animal protein had no effect on the total amount of feed fed, amount of feed consumed per fish, weight gain, or fillet protein and ash. Fish fed a diet containing 6% animal protein converted feed more efficiently than fish fed diets containing 0% and 3% animal protein. Fish fed to satiation daily consumed more feed, gained more weight, converted the feed less efficiently, and had a higher carcass yield, a higher level of visceral fat as compared to fish fed at a rate of >90 kg/ha per d. Feeding rate had no effect on fillet protein. Results from this study indicated that both a 28% and a 32% protein diet with or without animal protein provided the same growth rate of channel catfish raised in ponds from fingerlings to marketable size if feed is not restricted below a maximum rate of 90 kg/ha per d. Even though there were some interactions among the three factors evaluated, dietary protein levels of 28% to 32% and animal protein levels of 0% to 6% do not appear to markedly affect carcass yield and fillet proximate composition of pond-raised channel catfish. [source] Gastrin-Releasing Peptide, a Bombesin-like Neuropeptide, Promotes Cutaneous Wound HealingDERMATOLOGIC SURGERY, Issue 4 2002Yuji Yamaguchi MD Background. Little is known about the effects of neuropeptides on wound healing. Objective. To investigate the effect of gastrin-releasing peptide (GRP), one of the bombesin-like neuropeptides, on wound healing. Methods. The effects of GRP on cultured keratinocyte proliferation and migration were measured by BrdU uptake and in vitro scratch assay, respectively. Various concentrations of GRP ointments (0, 10,9, 10,8, 10,7, 10,6 M) were topically applied to 1.0 mm wounds on porcine flanks. Results. GRP stimulated keratinocyte growth and locomotion in a dose-dependent manner. Topical administration of GRP accelerated macroscopic epidermal regeneration in a dose-dependent manner, as measured by planimetry. Histologic studies also showed that GRP promoted reepithelialization, including epidermal thickness as well as superficial skin coverage. conclusion. Topical use of GRP may clinically accelerate wound healing of burns, injuries, chronic ulcers, and skin graft donor sites through the enhancement of keratinocyte growth and spreading. [source] Tailoring Cell Behavior on Polymers by the Incorporation of Titanium Doped Phosphate Glass Filler,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Wojciech Chrzanowski Abstract Understanding tissue response to materials, to enable modulation and guided tissue regeneration is one of the main challenges in biomaterials science. Nowadays polymers, glasses, and metals dominate as biomaterials. Often native properties of those materials are not sufficient and there is a need to combine them, so as to modify and adjust their properties to the application. The primary aim of this study was to improve cell response to polymer (PLDL) using phosphate glass as filler (titanium doped phosphate glass). As a control ,-tricalcium phosphate (TCP) filler was used. Various concentrations of the filler were used (10,40 vol%). Wetting behavior, , -potentials, mechanical and thermal properties, and human cells response to the materials were evaluated. Results showed that with increase in glass filler loading wettability improved, , -potentials dropped, and increase in stiffness of materials was observed. Importantly cell culture experiments showed more developed and well spread cells on the samples with glass content up to 20 vol%. Cells responded much more positively to the glass filled samples than to TCP filled. However, expression of osteocalcin and osteopontin, proteins that indicate formation of the mineralized structures was positive for all the samples including pure PLDL. It was concluded that due to improved wetting behavior, lower , -potentials, and specific chemistry of the glass filler it was possible to alter cells response, improve bioactivity of the polymer, and vary mechanical properties. [source] An Experimental Study On The Vasoconstriction Effect Of Calcium Hydroxide Using Rat MesenteryAUSTRALIAN ENDODONTIC JOURNAL, Issue 3 2003Izumi Kikuchi DDS Calcium hyroxide has been used for eliminating persistent intracanal exudation. In order to address the mechanism behind this action, we investigated whether calcium hydroxide solutions cause the constriction of microvessels in the mesenteric microcirculation bed of rats. The exteriorised mesentery from anaesthetised rats was spread in a chamber, and arterioles, venules and capillaries were viewed under a digital microscope. Various concentrations of calcium hydroxide solutions were applied for 10 sec, and the diameter of the microvessels was recorded. In arterioles, calcium hydroxide solutions caused rapid and transient constriction. A statistically significant difference versus original diameter was detected I min after the application of 4.0 times 10,3 mol/l and 1.0 times 10,2 mol/l solutions (p < 0.05, one-way analysis of variance and Tukey-Kramer test). No statistically significant constriction occurred in capillaries and venules. It was concluded that the arteriolar constriction might be an explanation for the exudation-controlling effect of intracanal calcium hyroxide dressings. [source] Antiproliferative effect of diallyl disulfide (DADS) on prostate cancer cell line LNCaPCELL BIOCHEMISTRY AND FUNCTION, Issue 5 2006D. N. Gunadharini Abstract Garlic has been used throughout the world to treat coughs, toothache, earache, dandruff, hypertension, hysteria, diarrhoea, dysentery, diptheria, vaginitis and many other conditions. Garlic contains a complex mixture of oil and water-soluble organosulfur compounds. Diallyl disulfide (DADS), an oil-soluble constituent of garlic seems to be effective in reducing tumour cells originating from colon, lung and skin. Hence our present study focuses on the dose-dependent effect of DADS on an androgen-dependent prostate cancer cell line. Various concentrations of DADS ranging from 25 to 100,µM were given to LNCaP cells and the activity of lactate dehydrogenase (LDH) prostatic acid phosphatase (PAcP) and the level of prostate specific antigen were studied. DADS reduced the secretory activity of LNCaP cells with the gradual increase in dosage. DADS was found to act as a good antiproliferative agent, which was confirmed by proliferation assay. DADS also induced apoptosis and nuclear segmentation in the higher doses. Copyright © 2005 John Wiley & Sons, Ltd. [source] Study of the MR relaxation of microglia cells labeled with Gd-DTPA-bearing nanoparticlesCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2009Emeline Julie Ribot Abstract Therapies involving cells as vehicles need to visualize in situ the trafficking of the cells concerned. This cellular imaging can be driven by cell contrast agent-based nanoparticle internalization and non-invasive MRI (magnetic resonance imaging) detection. Here, microglial cells, that would transport a suicide gene to a glioma, were incubated for different times, with various concentrations of silica nanoparticles on which numerous Gd-DTPA were grafted. The goal of this study was to investigate the repartition of cell-associated particles. MRI was used to quantitatively follow the particle uptake process. Fluorescence microscopy images showed that, although most of the nanoparticles were internalized, some remained adsorbed on the extracellular membrane surface. The cells were then submitted to various treatments: glycine to release bound nanoparticles and/or ultrasound to destroy the cell membranes. The R1 relaxation rates were measured at 4.7 T. R1 was maximal for 4,h of incubation, decreased after 8,h and remained stable for the 24 following hours. The magnetic resonance signal of ultrasonicated and glycine-treated cells made it possible to quantify the loss of bound nanoparticles after 8,h. Nevertheless, this release did not prevent cell detection since the internalized nanoparticles are enough concentrated to visualize the labeled cells even after 4 days of cell growth. These results highlight the compartmentalization of nanoparticles in microglia and the evolution of the MR signal of the labeled cells. This study could be of importance to interpret in vivo the MR signal changes that could occur after administration of such nanoparticle-labeled cells in therapeutic strategies. Copyright © 2009 John Wiley & Sons, Ltd. [source] Influence of Mg/Er co-doping on the principal laser parameters of LiNbO3 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2007Liang Sun Abstract Mg: Er: LiNbO3 crystals were grown by the Czochralski technique with various concentrations of MgO = 2 mol%, 4 mol%, 6 mol% and the fixed concentration of Er2O3= 1 mol% in the melt, and the 8 mol%Mg: 1 mol%Er: LiNbO3 crystal was fabricated by the Czochralski technique with special technology process. The crystals were treated by polarization, reduction and oxidation. The segregation coefficients of Mg2+ and Er3+ in Mg: Er: LiNbO3 crystals were measured by X-ray fluorescence spectrograph, as well as the crystal's defect structure and optical properties were analyzed by the UV-Vis, IR and fluorescent spectroscopy. The pump wavelength and the surge wavelength were determined. Using m-line method tested optical damage resistance of those crystals, the results show that photodamage threshold of Mg: Er: LiNbO3 crystals are higher than that of Er: LiNbO3 crystal, and the oxidation treat could enhance the photodamage resistant ability of crystals while the reduction treat could depress the ability. The optical damage resistance of 8 mol%Mg: 1 mol%Er: LiNbO3 crystal was the strongest among the samples, which was two orders magnitude higher than that of 1 mol%Er: LiNbO3 crystal. The dependence of the optical properties on defect structure of Mg: Er: LiNbO3 crystals was discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Integrating an Enzyme-Entrapped Conducting Polymer Electrode and a Prereactor in a Microfluidic System for Sensing GlucoseELECTROANALYSIS, Issue 6 2008Po-Chin Nien Abstract In this study, the flow injection analysis was applied to the enzyme-entrapped electrode on a chip for sensing glucose. The on-chip microelectrode was fabricated by the standard photolithography in clean-room environment and the microfluidic channel height of 100,,m on the chip was formed by poly(dimethylsiloxane). The conducting polymer, poly(3,4-ethylenedioxythiophene), PEDOT, was electropolymerized to entrap the coexisting glucose oxidase (GOD) by cyclic voltammetry (CV). The amount of enzyme entrapped in the matrix measured spectroscopically was about 0.101,U/cm2. At a flow rate of 10,ml/hr, the working electrode (Pt/PEDOT/GOD, WE1) was set at 0.7,V (vs. Ag/AgCl) and sensing of H2O2 was carried out by injecting samples with various concentrations of glucose (Glu). A linear relationship between the sensing current and the glucose concentration, ranging from 1 to 20,mM, was obtained with a sensitivity of 8,nA mm,2 mM,1. The response time and the recovery time were about 30 and 230,s, respectively. For a single-potential test, the oxidation currents of 0.08,mM ascorbic acid (AA) and a blend of 0.08,mM AA and 10,mM Glu reached 31.3% and 145.5%, respectively, when compared with the oxidation current of 10,mM Glu alone. However, when a pre-reactor (WE2) was set at the same potential (0.7,V) before the main enzyme integrated electrode (WE1), the oxidation current for the above mixed solution reached 99.6% of the original one. [source] Red blood cell quantification microfluidic chip using polyelectrolytic gel electrodesELECTROPHORESIS, Issue 9 2009Kwang Bok Kim Abstract This paper reports on a novel microfluidic chip with polyelectrolytic gel electrodes (PGEs) used to rapidly count the number of red blood cells (RBCs) in diluted whole blood. The proposed microdevice is based on the principle that the impedance across a microchannel between two PGEs varies sensitively as RBCs pass through it. The number and amplitude of impedance peaks provide the information about the number and size of RBCs, respectively. This system features a low-voltage dc detection method and non-contact condition between cells and metal electrodes. Major advantages include stable detection under varying cellular flow rate and position in the microchannel, little chance of cell damage due to high electric field gradient and no surface fouling of the metal electrodes. The performance of this PGEs-based system was evaluated in three steps. First, in order to observe the size-only dependence of the impedance signal, three different sizes of fluorescent microbeads (7.2, 10.0, and 15.0,,m; Bangs laboratories, USA) were used in the experiment. Second, the cell counting performance was evaluated by using 7.2,,m fluorescent microbeads, similar in size to RBCs, in various concentrations and comparing the results with an animal hematoanalyzer (MS 9-5; Melet schloesing laboratories, France). Finally, in human blood sample tests, intravenously collected whole blood was just diluted in a PBS without centrifuge or other pretreatments. The PGE-based system produced almost identical number of RBCs in over 800-fold diluted samples to the results from a commercialized human hematoanalyzer (HST-N402XE; Sysmex, Japan). [source] Development of off-line and on-line capillary electrophoresis methods for the screening and characterization of adenosine kinase inhibitors and substratesELECTROPHORESIS, Issue 12 2006Jamshed Iqbal Abstract Fast and convenient CE assays were developed for the screening of adenosine kinase,(AK) inhibitors and substrates. In the first method, the enzymatic reaction was performed in a test tube and the samples were subsequently injected into the capillary by pressure and detected by their UV absorbance at 260,nm. An MEKC method using borate buffer (pH,9.5) containing 100,mM SDS (method,A) was suitable for separating alternative substrates (nucleosides). For the CE determination of AMP formed as a product of the AK reaction, a phosphate buffer (pH,7.5 or 8.5) was used and a constant current (95,,A) was applied (method,B). The methods employing a fused-silica capillary and normal polarity mode provided good resolution of substrates and products of the enzymatic reaction and a short analysis time of less than 10,min. To further optimize and miniaturize the AK assays, the enzymatic reaction was performed directly in the capillary, prior to separation and quantitation of the product employing electrophoretically mediated microanalysis (EMMA, method,C). After hydrodynamic injection of a plug of reaction buffer (20,mM Tris-HCl, 0.2,mM MgCl2, pH,7.4), followed by a plug containing the enzyme, and subsequent injection of a plug of reaction buffer containing 1,mM,ATP, 100,,M adenosine, and 20,,M,UMP as an internal standard,(I.S.), as well as various concentrations of an inhibitor, the reaction was initiated by the application of 5,kV separation voltage (negative polarity) for 0.20,min to let the plugs interpenetrate. The voltage was turned off for 5,min (zero-potential amplification) and again turned on at a constant current of ,60,,A to elute the products within 7,min. The method employing a polyacrylamide-coated capillary of 20,cm effective length and reverse polarity mode provided good resolution of substrates and products. Dose,response curves and calculated Ki values for standard antagonists obtained by CE were in excellent agreement with data obtained by the standard radioactive assay. [source] Odor-mediated patch choice in the parasitoid Venturia canescens: temporal decision dynamicsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2009Yin-Quan Liu Abstract Parasitoids foraging for hosts in a heterogeneous environment would greatly benefit if they could decide already from a distance in which areas search for resources would be most profitable and to avoid areas of low fitness returns. Interestingly, the temporal dynamics of the decision process in parasitoid patch choice have rarely been investigated. In a Y-tube olfactometer, we tested whether thelytokous and arrhenotokous females of the parasitoid wasp Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) respond to differences in cues indicating the quality of a host-containing patch and choose more profitable patches. Special attention was given to the time it took females to make their choices (patch choice time) when differences in patch quality were either qualitative (absence vs. presence of hosts and kairomone) or quantitative (various concentrations of hosts and kairomone, and presence of competitors). We found that both thelytokous and arrhenotokous wasps only chose the higher-quality patch based on odor cues when the difference was qualitative. When patches differed only with respect to the number of hosts, or the presence or absence of competing female parasitoids, no significant preference could be found in females of either strain of the parasitoid. In contrast, both the time until females reached the junction of the Y-tube olfactometer (response time) and the time until females decided for either patch (decision time) varied with parasitoid strain and odor treatment. Thelytokous wasps were faster than arrhenotokous wasps in their response time and in their decision time. However, females of both strains responded faster with increasing number of total hosts releasing kairomone. Yet, decision time for patches did not significantly vary as a function of patch quality offered to Venturia wasps. [source] Influence of the SCGE protocol on the amount of basal DNA damage detected in the Mediterranean mussel, Mytilus galloprovincialisENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 8 2006Nicola Machella Abstract Genotoxicity studies using the single cell gel electrophoresis (SCGE) assay indicate that basal levels of DNA strand breaks (SBs) in marine invertebrates are higher and more variable than those in marine vertebrates. This elevated level of DNA damage was attributed to a large number of alkali-labile sites, which are characteristic of the tightly-packaged DNA in invertebrate cells. To investigate if altering the SCGE protocol can artificially modulate high levels of SBs, SCGE experiments were performed on haemocytes from the Mediterranean mussel (Mytilus galloprovincialis) using proteinase K (PK) digestion in combination with assay buffers containing various concentrations of EDTA. In addition, the effects of Trolox® (soluble antioxidant) and aurintricarboxylic acid (ATA; inhibitor of Ca2+/Mg2+ -dependent nucleases) also were tested. The levels of SBs in M. galloprovicialis cells were compared with SBs in cells from a terrestrial mollusk (the snail Helix aspersa), and a teleost fish (the seabass Dicentrarchus labrax). The integrity of M. galloprovincialis DNA isolated with phenol extractions using EDTA, Trolox, and ATA was further assayed by gel electrophoresis. High SBs in mussel cells were reduced by combining EDTA with PK digestion, or using Trolox® or ATA during cell processing for the SCGE assay. Snails and seabass had lower levels of SBs in the SCGE assay, and the levels were not affected by the protocol modifications. Adding EDTA, Trolox®, or ATA to phenol extractions of M. galloprovincialis genomic DNA also reduced the extent of DNA fragmentation. These results suggest that the internal fluids of M. galloprovincialis may increase the basal levels of DNA SBs through oxidative and/or enzyme-mediated pathways. M. galloprovincialis is used extensively as a sentinel species for assessing the genotoxic hazard of marine pollutants. Our data suggest that the SCGE protocol should be carefully considered when assessing DNA damage in these species. Environ. Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source] Mechanism of DNA damage by cadmium and interplay of antioxidant enzymes and agentsENVIRONMENTAL TOXICOLOGY, Issue 2 2007Veera L. D. Badisa Abstract Cadmium is an environmental toxicant, which causes cancer in different organs. It was found that it damages DNA in the various tissues and cultured cell lines. To investigate the mechanism of DNA damage, we have studied the effect of cadmium-induced DNA damage in plasmid pBR322 DNA, and the possible ameliorative effects of antioxidative agents under in vitro conditions. It was observed that cadmium alone did not cause DNA damage. However, it caused DNA damage in the presence of hydrogen peroxide, in a dose dependent manner, because of production of hydroxyl radicals. Findings from this study show the conversion of covalently closed circular double-stranded pBR 322 DNA to the open circular and linear forms of DNA when treated with 10 ,M cadmium and various concentrations of H2O2. The conversion was due to nicking in DNA strands. The observed rate of DNA strand breakage was dependent on H2O2 concentration, temperature, and time. Metallothionein I failed to prevent cadmium-induced DNA nicking in the presence of H2O2. Of the two antioxidant enzymes (catalase and superoxide dismutase) studied, only catalase conferred significant (50,60%) protection. EDTA and DMSO exhibited protection similar to catalase, while mannitol showed only about 20% protection against DNA damage. Ethyl alcohol failed to ameliorate cadmium-induced DNA strands break. From this study, it is plausible to infer that cadmium in the presence of hydrogen peroxide causes DNA damage probably by the formation of hydroxyl ions. These results may indicate that cadmium in vivo could play a major role in the DNA damage induced by oxidative stress. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 144,151, 2007. [source] Alteration of normal cellular profiles in the scleractinian coral (Pocillopora damicornis) following laboratory exposure to fuel oilENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2006Luc Rougée Abstract Petroleum contamination from oil spills is a continuing threat to our ocean's fragile ecosystems. Herein, we explored the effects of the water-soluble fraction of crude oil on a stony coral, Pocillopora damicornis (Linneaeus 1758). We developed methods for exposing corals to various concentrations of crude oil and for assessing the potential molecular responses of the corals. Corals were exposed to water-accommodated fraction solutions, and appropriate cellular biomarkers were quantified. When compared to the "healthy" control specimens, exposed corals exhibited shifts in biomarker concentrations that were indicative of a shift from homeostasis. Significant changes were seen in cytochrome P450 1-class, cytochrome P450 2-class, glutathione- S -transferase-pi, and cnidarian multixenobiotic resistance protein-1 biomarkers, which are involved the cellular response to, and manipulation and excretion of, toxic compounds, including polycyclic aromatic hydrocarbons. A shift in biomarkers necessary for porphyrin production (e.g., protoporphyrinogen oxidase IX and ferrochelatase) and porphyrin destruction (e.g., heme oxygenase-1 and invertebrate neuroglobin homologue) illustrates only one of the cellular protective mechanisms. The response to oxidative stress was evaluated through measurements of copper/zinc superoxide dismutase-1 and DNA glycosylase MutY homologue-1 concentrations. Likewise, changes in heat shock protein 70 and small heat shock proteins indicated an adjustment in the cellular production of proteins. Finally, the results of this laboratory study were nearly identical to what we observed previously among corals of a different species, Porites lobata, exposed to an oil spill in the field after the grounding of the Merchant Vessel Kyowa Violet. [source] Influence of 4-nonylphenol on the structure of nematode communities in freshwater microcosmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2004Sebastian Höss Abstract We investigated the effect of 4-nonylphenol (NP) on nematode communities in the sediment of freshwater microcosms. Seven treatments were dosed with various concentrations of NP over a period of six weeks by using a controlled-release method (NP1-NP7; maximum sediment concentrations: 0.29,3.37 mg/kg dry wt). Four microcosms were not exposed to NP and served as controls. Nematode communities were analyzed over a period of 15 weeks, including sampling dates before, within, and after the NP application. Communities were characterized in terms of total nematode abundance and species diversity (Shannon index and evenness), as well as composition of species, feeding types, and different life-history strategists (maturity index [MI]). Species composition was analyzed by using a multivariate method (principal response curves). Total nematode abundance and species diversity were not affected in any of the NP-treated microcosms. However, in the highest dosed treatment, NP-induced changes in the nematode communities occurred. Species and feeding types composition, as well as the MI, were affected in the postapplication period, with species composition being altered most clearly. In the highest dosed treatment, deposit-feeding species, classified as colonizers (Eumonhystera), increased in dominance, whereas epistrate feeders and chewers (Prodesmodora and Tobrilus) decreased in relative abundance compared to the control. [source] Effects of 4-nonylphenol and 4- tert -octylphenol on sex differentiation and vitellogenin induction in medaka (Oryzias latipes)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2003Masanori Seki Abstract Medaka (Oryzias latipes) were continuously exposed to various concentrations of two alkylphenols, 4-nonylphenol (NP) and 4- tert -octylphenol (OP), from fertilized eggs to 60 d posthatch. The effects on sexual differentiation and hepatic vitellogenin (VTG) induction in medaka were assessed to elucidate the lowest-observed-effect concentrations (LOECs) of NP and OP for these events during early life stages. The LOECs of NP and OP for these events were 11.6 and 11.4 ,g/L, respectively. These results suggest that NP and OP may have adverse effects at similar concentrations during early life stage in medaka. Additionally, we investigated whether the abnormal sex differentiation induced by these alkylphenols would be permanent or reversible once the medaka were returned to clean water. The appearance of the secondary sex characteristics reverted from female to male when fish were returned to clean water. However, gonadal histology showed that intersex gonads still existed, even after the fish were transferred to clean water for two months. These results suggest that the induced feminization of secondary sex characteristics in medaka exposed to alkylphenols during the stage of sexual differentiation may not always be permanent, but the gonadal alteration (testisova) may continue much longer. [source] Induction of morphological deformities in Chironomus tentans exposed to zinc- and lead-spiked sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Edward A. Martinez Abstract Laboratory experiments were used to assess morphological responses of Chironomus tentans larvae exposed to three levels of zinc and lead. Chironomus tentans egg masses were placed into triplicate control and metal-spiked aquaria containing the measured concentrations 1,442, 3,383, and 5,562 ,g/g Pb dry weight and 1,723, 3,743, and 5,252 ,g/g Zn dry weight. Larvae were collected at 10-d intervals after egg masses were placed in aquaria until final emergence. Larvae were screened formouthpart deformities and metal body burdens. Deformities increased with time of exposure in both Zn and Pb tanks. Deformity rates between the three Zn concentrations differed statistically, with low and medium Zn levels containing the highest overall deformity rates of 12%. Deformity rates for larvae held in the Pb aquaria were found to differ significantly. Larvae in the low-Pb tanks had a deformity rate of 9%. Larvae and water from both the Zn and Pb aquaria had increasing metal concentrations with increasing sediment metal concentration. Results demonstrate that Zn and Pb each induce chironomid mouthpart deformities at various concentrations. However, a clear dose-related response was not demonstrated. Our research provides more support for the potential use of chironomid deformities as a tool for the assessment of heavy metal pollution in aquatic systems. [source] The effects of acetylsalicylic acid on proliferation, apoptosis, and invasion of cyclooxygenase-2 negative colon cancer cellsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 11 2002H.-G. Yu Summary Background Acetylsalicylic acid (ASA, aspirin), the most common nonsteroidal anti-inflammatory drug (NSAID), has been shown to have a protective effect against the incidence and mortality of colorectal cancer. However, the mechanism of its anticancer function remains unclear. The aim of this study was to determine the effects of acetylsalicylic acid on proliferation, apoptosis, and invasion in human cyclooxygenase-2 (COX-2) negative colorectal cancer cell lines. Materials and Methods After treatment with various concentrations of ASA, cell proliferation was measured in the human colon cancer cell line SW480. Apoptotic cells were identified by transmission electron microscopy, acridine orange staining, and flow cytometry. The invasive potential of SW480 cells was detected using an in vitro invasion assay. The production of carcinoembryonic antigen was measured by microparticle enzyme immunoassay. Expression of Bcl2, Bax, CD44v6, and nm23 were evaluated by immunocytochemistry. Results ASA significantly inhibited the proliferation of SW480 cells and stimulated apoptosis. Production of carcinoembryonic antigen and the invasive potential of SW480 cells were also inhibited by ASA. After treatment with ASA, down-regulation of Bcl2 and CD44v6 expression and up-regulation of nm23 expression were observed in SW480 cells. No obvious effect of ASA was found on Bax expression. Conclusion Our findings reveal that ASA inhibits the proliferation and promotes apoptosis in the human colon cancer cell line SW480. Down-regulation of Bcl2 expression might represent a potential mechanism by which ASA induces apoptosis in this COX-2 negative colon cancer cell line. Our results also suggest that ASA decreases the invasive potential of these colon cancer cells. Decreased CEA content and CD44v6 expression and elevated nm23 expression may contribute to the effect of ASA on invasive potential of SW480 colon cancer cells. [source] Alkaline neutralization of crude soybean oil by various adsorbentsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 3 2008Sukran Kuleasan Abstract The effect of sodium hydroxide in neutralization was increased by using various adsorbents. NaOH in various concentrations was attached to the particles of Kieselguhr, Celite and Bentonite. The neutralization reaction was performed at ambient temperature, and different reaction times were applied. The soap formed after reaction was removed by centrifugation; thus, washing and drying steps were omitted. The amount of remaining soap, the acidity and color of oils were determined after each treatment. According to the results, free fatty acid neutralization in crude oil was achieved by Kieselguhr application. In this process, 9.5% NaOH was applied for 60,min of reaction time. The free fatty acid content of crude oil was decreased from 0.56 to 0.14%, and the remaining soap was found at 34,mg/kg after centrifugation. The use of adsorbents increased the efficiency of NaOH in the neutralization reaction and in the removal of soap from the neutralized oil. Neutralization with support material is a new and promising approach. The application is energy saving, more practical and in accordance with the strict environmental legislation about waste disposal. [source] Body size and food thresholds for zero growth in Dreissena polymorpha: a mechanism underlying intraspecific competitionFRESHWATER BIOLOGY, Issue 12 2008ALEXANDER WACKER Summary 1. Dreissena polymorpha is an extraordinarily successful invasive species that shows high recruitment of small juvenile mussels on established mussel banks. Such juvenile settlement on, and overgrowth of, large adult mussels; however, leads to competition with adults, and often at high densities and low-food concentrations. 2. The concept of food thresholds for zero growth has been a powerful approach to explaining size-related exploitative competition in different zooplankton species. We applied it to investigate whether food threshold concentrations for zero growth (C0) differ between juvenile and adult zebra mussels. 3. By determining body mass growth at various concentrations of a diet mixture (Nannochloropsis limnetica and Isochrysis aff. galbana) we demonstrate that the threshold food concentration for growth of juvenile mussels (C0 = 0.08 mg C L,1) is substantially lower than that for adults (C0 = 0.36 mg C L,1). 4. This indicates that, at low food availability, juvenile zebra mussels are competitively superior to their larger conspecifics. Within zebra mussel banks plankton food is substantially depleted and so the observed mechanism might ensure juvenile success and therefore the regeneration of mussel banks in nature. [source] Development of a Direct Alcohol Alkaline Fuel Cell StackFUEL CELLS, Issue 4 2010D. Gaurava Abstract Direct alcohol alkaline fuel cells (DAAFC) are one of the potential fuel cell types in the category of low temperature fuel cells, which could become an energy source for portable electronic equipment in future. In the present study, a simple DAAFC stack has been developed and studied to evaluate the maximum performance for a given fuel (methanol or ethanol) and electrolyte (KOH) at various concentrations and temperatures. The open circuit voltage of the stack of four cells was nearly 4.0,V. A particular combination, 2,M fuel (methanol or ethanol) and 3,M KOH, results in maximum power density of the stack. The maximum power density obtained from the DAAFC stack (25,°C) was 50,mW,cm,2 at 20,mA,cm,2 for methanol and 17,mA,cm,2 for ethanol. The stack power density corroborated with that obtained from a single cell, indicating there was no further loss in the stack. [source] Electrochemical Reduction of Oxygen on Carbon Supported Pt and Pt/Ru Fuel Cell Electrodes in Alkaline SolutionsFUEL CELLS, Issue 4 2003E.H. Yu Abstract A study of O2 reduction in 1 M NaOH solution at gas diffusion electrodes made from carbon supported Pt and Pt/Ru catalysts is reported. Two Tafel regions were observed for both the Pt and Pt/Ru electrodes. Although the same mechanism was suggested for oxygen reduction on both Pt and Pt/Ru catalysts, the O2 reduction activity was lower on Ru. Electrochemical Impedance Spectroscopy (EIS) analysis was carried out at different potentials and showed the significant contribution of diffusion on the reaction process and kinetics. The effect of methanol on O2 reduction was investigated in solutions containing various concentrations of methanol. The electrode performance deteriorated with increasing methanol concentration because of a mixed cathode potential. The methanol tolerance, i. e., the methanol concentration which polarises the O2 reduction reaction for O2 reduction, at the Pt/C electrode with a Pt loading of 1.2 mg cm,2 is 0.2 M methanol in 1 M NaOH. [source] Selective Zinc(II)-Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Krishanu Sarkar Abstract A highly ordered 2D-hexagonal mesoporous silica material is functionalized with 3-aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4-methyl-2,6-diformyl phenol. Powder X-ray diffraction, transmission electron microscopy, N2 sorption, Fourier transform infrared spectroscopy, and UV-visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn2+ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn2+ -bound mesoporous material increases significantly upon addition of various concentrations of Zn2+, while the introduction of other biologically relevant (Ca2+, Mg2+, Na+, and K+) and environmentally hazardous transition-metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn2+, evident from the large binding constant value (0.87,×,104M,1). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn2+ from a mixture of ions that contains Zn2+ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy. [source] Controlled Degradability of Polysaccharide Multilayer Films In Vitro and In Vivo,ADVANCED FUNCTIONAL MATERIALS, Issue 11 2005C. Picart Abstract This article demonstrates the possibility of tuning the degradability of polysaccharide multilayer films in vitro and in vivo. Chitosan and hyaluronan multilayer films (CHI/HA) were either native or crosslinked using a water soluble carbodiimide, 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (EDC) at various concentrations in combination with N-hydroxysulfosuccinimide. The in-vitro degradation of the films in contact with lysozyme and hyaluronidase was followed by quartz crystal microbalance measurements, fluorimetry, and confocal laser scanning microscopy after labeling of the chitosan with fluorescein isothiocyanate (CHIFITC). The native films were subjected to degradation by these enzymes, and the crosslinked films were more resistant to enzymatic degradation. Films made of chitosan of medium molecular weight were more resistant than films made of chitosan-oligosaccharides. The films were also brought in contact with plasma, which induced a change in film structure for the native film but did not have any effect on the crosslinked film. The in-vitro study shows that macrophages can degrade all types of films and internalize the chitosan. The in-vivo degradation of the films implanted in mouse peritoneal cavity for a week again showed an almost complete degradation of the native films, whereas the crosslinked films were only partially degraded. Taken together, these results suggest that polysaccharide multilayer films are of potential interest for in-vivo applications as biodegradable coatings, and that degradation can be tuned by using chitosan of different molecular weights and by controlling film crosslinking. [source] Interleukin-4 supports interleukin-12-induced proliferation and interferon-, secretion in human activated lymphoblasts and T helper type 1 cellsIMMUNOLOGY, Issue 1 2006Martin A. Kriegel Summary Interleukin-12 (IL-12) and IL-4 are known to differentially promote T helper (Th) cell differentiation. While IL-12 induces interferon-, (IFN-,) production and maturation of Th1 cells, IL-4 is thought to antagonize IL-12 and to favour Th2 development. Here we studied the combined action of various concentrations of common ,-chain (,c -chain) cytokines, including IL-4 and the Th1 cytokine IL-12, in human activated lymphoblasts and Th1 cells. IL-4 and IL-7 potentiated IL-12-induced proliferation at every concentration tested (1,10 ng/ml) without increasing rescue from apoptosis, indicating that proliferation was directly affected by these cytokine combinations. With regards to cytokine secretion, IL-2 together with IL-12 initiated tumour necrosis factor-, synthesis, enhanced IFN-, production, and shedding of soluble IL-2 receptor , as expected. Importantly, combining IL-4 with IL-12 also enhanced IFN-, secretion in lymphoblasts and a Th1 cell line. Investigating signal transduction in lymphoblasts induced by these cytokines, we found that not only IL-2 but also IL-4 enhances signal transducer and activator of transcription 3 (STAT3) tyrosine phosphorylation by IL-12. Tyrosine phosphorylations of janus kinase 2 (JAK-2), tyrosine kinase 2 (TYK2), extracellular signal-regulated kinase (ERK) and STAT4, STAT5 and STAT6 were not potentiated by combinations of these cytokines, suggesting specificity for increased STAT3 phosphorylation. In conclusion, two otherwise antagonizing cytokines co-operate in activated human lymphoblasts and Th1 cells, possibly via STAT3 as a converging signal. These data demonstrate that IL-4 can directly enhance human Th1 cell function independently of its known actions on antigen-presenting cells. These findings should be of importance for the design of cytokine-targeted therapies of human Th-cell-driven diseases. [source] Role of venom and ovarian proteins in immune suppression of Ostrinia furnacalis (Lepidoptera: Pyralidae) larvae parasitized by Macrocentrus cingulum (Hymenoptera: Braconidae), a polyembryonic parasitoidINSECT SCIENCE, Issue 2 2007YONG LI Abstract Venom and ovarian proteins in braconid and ichneumonid wasps play an important role in the successful parasitism of their host, especially for immune suppression immediately after oviposition. In this study, we compared the effect of venom and ovarian proteins collected from the female wasps of Macrocentrus cingulum, a polyembryonic parasitoid of the larvae of Ostrinia funacalis, on the encapsulation capacity of Sephadex A-25 beads at 4 h and 24 h post-injection both in vivo and in vitro. The results showed that the ovarian proteins significantly interfered with the encapsulation capacity of hemocytes in a dose-dependent manner. Spreading and viability of hemocytes in O. furnacalis was not disrupted by venom and ovarian proteins at various concentrations injected. It seems likely that the ovarian proteins from M. cingulum play a role in suppressing the encapsulation capacity of host hemocytes. [source] Efficacy of various concentrations of NaOCl and instrumentation techniques in reducing Enterococcus faecalis within root canals and dentinal tubulesINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2006V. B. Berber Abstract Aim, To evaluate the efficacy of 0.5%, 2.5% and 5.25% sodium hypochlorite (NaOCl) as intracanal irrigants associated with hand and rotary instrumentation techniques against Enterococcus faecalis within root canals and dentinal tubules. Methodology, A total of 180 extracted human premolar teeth were infected for 21 days with E. faecalis. The specimens were divided into 12 groups, as follows: group 1: 5.25% NaOCl + Hybrid technique (Valdrighi et al. 1998); group 2: 5.25% NaOCl + nickel,titanium (NiTi) rotary technique 4 mm shorter than the apex (by FOP-UNICAMP); group 3: 5, 25% NaOCl + NiTi rotary technique (Hero 642); group 4: 2.5% NaOCl +Hybrid technique; group 5: 2.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 6: 2.5% NaOCl + NiTi rotary technique (Hero 642); group 7: 0.5% NaOCl + Hybrid technique; group 8: 0.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 9: 0.5% NaOCl + NiTi rotary technique (Hero 642); group 10: sterile saline solution + Hybrid technique; group 11: sterile saline solution + NiTi rotary technique 4 mm shorter than the apex; group 12: sterile saline solution + NiTi rotary technique (Hero 642). Canals were sampled before and after preparation. After serial dilution, samples were plated onto brain heart infusion (BHI) agar, and the colony forming units (CFU) that were grown were counted. The teeth were sectioned into three thirds and dentine chips were removed from the canals with conical burs. The samples obtained with each bur were immediately collected into test tubes containing BHI broth, and were incubated at 37 °C and plated onto BHI agar. The CFU were counted and analysed. Results, At all depths and thirds of the root canals and for all techniques used, 5.25% NaOCl was shown to be the most effective irrigant solution tested when dentinal tubules were analysed, followed by 2.5% NaOCl. No differences among concentrations in cleaning the canals were found. Conclusions, Especially at higher concentrations, NaOCl, was able to disinfect the dentinal tubules, independent of the canal preparation technique used. [source] High salt diets dose-dependently promote gastric chemical carcinogenesis in Helicobacter pylori -infected Mongolian gerbils associated with a shift in mucin production from glandular to surface mucous cellsINTERNATIONAL JOURNAL OF CANCER, Issue 7 2006Sosuke Kato Abstract Intake of salt and salty food is known as a risk factor for gastric carcinogenesis. To examine the dose-dependence and the mechanisms underlying enhancing effects, Mongolian gerbils were treated with N -methyl- N -nitrosourea (MNU), Helicobacter pylori and food containing various concentrations of salt, and were sacrificed after 50 weeks. Among gerbils treated with MNU and H. pylori, the incidences of glandular stomach cancers were 15% in the normal diet group and 33%, 36% and 63% in the 2.5%, 5% and 10% NaCl diet groups, showing dose-dependent increase (p < 0.01). Intermittent intragastric injection of saturated NaCl solution, in contrast, did not promote gastric carcinogenesis. In gerbils infected with H. pylori, a high salt diet was associated with elevation of anti- H. pylori antibody titers, serum gastrin levels and inflammatory cell infiltration in a dose-dependent fashion. Ten percent NaCl diet upregulated the amount of surface mucous cell mucin (p < 0.05), suitable for H. pylori colonization, despite no increment of MUC5AC mRNA, while H. pylori infection itself had an opposing effect, stimulating transcription of MUC6 and increasing the amount of gland mucous cell mucin (GMCM). High salt diet, in turn, decreased the amount of GMCM, which acts against H. pylori infection. In conclusion, the present study demonstrated dose-dependent enhancing effects of salt in gastric chemical carcinogenesis in H. pylori -infected Mongolian gerbils associated with alteration of the mucous microenvironment. Reduction of salt intake could thus be one of the most important chemopreventive methods for human gastric carcinogenesis. © 2006 Wiley-Liss, Inc. [source] Arbutin determination in medicinal plants and creamsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2009W. Thongchai Synopsis A simple flow injection (FI) manifold with spectrophotometric detection was fabricated and tested for arbutin determination. It is based on the measurement of a red-coloured product at 514 nm formed by the complexation reaction between arbutin and 4-aminoantipyrine (4-AP) in the presence of hexacyanoferrate (III) in an alkaline medium. On injecting 300 ,L standard solutions at various concentrations of arbutin into the FI system under optimum conditions, a linear calibration graph over the range of 1.0,30.0 ,g mL,1 arbutin was established. It is expressed by the regression equation y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). The detection limit (3,) and the limit of quantitation (10,) were 0.04 ,g mL,1 and 0.13 ,g mL,1, respectively. The RSD of intraday and interday precisions were found to be 1.2,1.4% and 1.7,2.7%, respectively. The method was successfully applied in the determination of arbutin in four selected fruits and three commercial whitening cream extracts with the mean recoveries of the added arbutin over the range of 96.2,99.0%. No interference effects from some common excipients used in commercial whitening creams were observed. The method is simple, rapid, selective, accurate, reproducible and relatively inexpensive. Résumé Un collecteur simple pour injection en flux (FI) avec détection spectrométrique a été fabriqué et testé pour le dosage de l'arbutine. Son principe repose sur la mesure à 514 nm du produit rouge formé par la réaction de complexation entre l'arbutine et le 4-aminoantipyrine (4-AP) en présence d'hexacyanoferrate (III) en milieu alcalin. On procède à une injection de 300 ,L des solutions standards à diverses concentrations d'arbutine dans le système FI aux conditions optimales, puis on réalise un graphe de calibration linéaire dans l'intervalle de 1,0 à 30,0 ,g mL,1 d'arbutine. Le graphe correspond à l'équation de régression y = 0.2188 ± 0.0036x + 0.1019 ± 0.0366 (r2 = 0.9990, n = 5). La limite de détection (3,) et la limite de quantification (10,) sont respectivement de 0.04 ,g mL,1 et 0.13 ,g mL,1. La RSD des précisions intra et inter jours sont respectivement de 1.2,1.4% et 1.7,2.7%. La méthode a été appliquée avec succès à la mesure de l'arbutine dans 4 fruits sélectionnés et 3 extraits de crèmes de blanchiment commercialisées avec une recouvrance moyenne de l'arbutine ajoutée de 96.2 à 99%. Aucune interférence avec les excipients communément utilisés dans les crèmes de blanchiment commerciales n'a été observée. La méthode est simple, rapide, sélective, précise, reproductible et relativement bon marché. [source] Thymol and modified atmosphere packaging to control microbiological spoilage in packed fresh cod hamburgersINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2009Maria Rosaria Corbo Summary A study on the use of mild technologies to produce packaged fish hamburgers was presented. In particular, the antimicrobial effect of some natural compounds (carvacrol, eugenol, thymol, green tea extract, rosemary extract, grapefruit seed extract and lemon extract), at various concentrations (500,10 000 ppm), was screened in vitro against the main fish spoilage micro-organisms (Shewanella putrefaciens and Photobacterium phosphoreum). Lemon extract and thymol, in combination with modified atmosphere packaging, showed the greatest inhibition activity, therefore, thymol was subsequently used as an ingredient for producing fish hamburgers. Results pointed out that this combination is effective in controlling the growth of microbial species mainly involved in fresh fish spoilage; in particular, it significantly (P < 0.05) reduced the growth rate of bacterial population, performing about 4.8 log CFU g,1 and 6.5 log CFU g,1 reduction of the hydrogen sulphide producing bacteria and psychrotrophic aerobic specific spoilage organisms cell load, respectively, if compared with the control. [source] | |||||||||||||||||||||||||||||||||||||||||||