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Negligible Levels (negligible + level)
Selected AbstractsCarbothermal synthesis of vanadium nitride: Kinetics and mechanismINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 6 2006A. Ortega Constant rate thermal analysis (CRTA) has been used for the first time to study the kinetics of the carbothermal reduction of V2O5 in nitrogen to obtain vanadium nitride. It is noteworthy to point out that CRTA method allows both a good control of pressure in the sample surroundings and the use of reaction rates low enough to keep temperatures gradients at a negligible level to avoid any heat or mass transfer phenomena. This method allows one to control the texture and the structure of many materials through kinetic control of the thermal treatment of the precursors. The precise control of the external parameters of the reaction shows that CRTA is an attractive method for kinetic studies and leads to more reliable kinetic data. It has been shown that the carbothermal synthesis of vanadium nitride is best described by a three-dimensional diffusion kinetic model (the Jander equation) with an activation energy which falls in the range of 520,540 kJ/mol. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 369,375, 2006 [source] Self-sterilizing catheters with titanium dioxide photocatalyst thin films for clean intermittent catheterization: Basis and study of clinical useINTERNATIONAL JOURNAL OF UROLOGY, Issue 5 2007Yuki Sekiguchi Objective: Clean intermittent catheterization (CIC) requires a large number of disposable catheters or a large amount of water and disinfectant. We made titanium dioxide (TiO2)-coated catheters for CIC using technology we have developed previously, and examined the photocatalytic antibacterial effect of this catheter using only light energy and the safety of this type of catheter for practical clinical use. Methods: TiO2 -coated catheters were filled with bacterial cell suspensions and illuminated with a 15-W black-light lamp for testing antibacterial potency. Next, we soaked control toxic materials (zinc diethyldithiocarbamate) and the tips of TiO2 -coated catheters in M05 medium, and evaluated cell toxicity from the numbers of V79 colonies in these dilutions. Then, bodyweight curves and histological tissue changes were observed over a period of time in mouse-transplanted TiO2 -coated catheters and control catheters. Finally, we investigated the use of these TiO2 -coated catheters in 18 patients by questionnaire and bacterial culture of TiO2 -coated catheters and control catheters. Results: The survival rate of Escherichia coli in the liquid inside the TiO2 catheter decreased to a negligible level within 60 min under ultraviolet (UV)-A illumination. The survival rate of Staphylococcus aureus, Pseudomonas aeruginosa and Serratia marcescens also decreased to a negligible level within 60 min. V79 cells showed no cytotoxicity of this catheter, and there was no difference in bodyweight or foreign body reaction between mouse-transplanted TiO2 -coated catheters and control catheters. In a preliminary clinical analysis of 18 patients who voluntarily used this catheter, the rate of positive bacterial culture of the tips of TiO2 -coated catheters was 20% versus 60% for conventional catheters after 4 weeks of use. Conclusion: TiO2 -coated silicone catheters were easily sterilized under certain light sources and were shown to be safe in an experiment using cultured cells and in animal experiments. Sterilizing catheters with TiO2 photocatalyst thin films are expected to be used clinically for clean intermittent catheterization after proper modification based on this study. [source] Commodity price stabilisation: macroeconomic impacts and policy optionsAGRICULTURAL ECONOMICS, Issue 1 2000Chinna A. Kannapiran Abstract A macroeconometric simulation study is undertaken to evaluate the impact of commodity price stabilisation (CPS) schemes for the export tree crop industry in Papua New Guinea. The findings suggest that there is a negligible level of favourable macroeconomic impacts of CPS. Contrary to the expectation, CPS adversely affects the stability of monetary and external sectors (BOP). CPS policy has failed to stabilise the macroeconomy. The price stabilisation policies are no longer appropriate from the macroeconomic point of view. Technical change, futures market and rural savings are the possible alternative policy options to manage the price risk. [source] Glutathione S -transferase detoxification as a potential pyrethroid resistance mechanism in the maize weevil, Sitophilus zeamaisENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2003Daniel B. Fragoso Abstract Insecticide resistance patterns among 16 Brazilian populations of the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), were recognized by surveying resistance to three organophosphates (chlorpyrifos-methyl, malathion, and pirimiphos-methyl) and three pyrethroids (cypermethrin, deltamethrin, and permethrin). Two population clusters were obtained: one with three populations (Bragança Paulista, Cristalina, and Nova Andradina) showing low frequency of cypermethrin resistance (13,36%) and negligible frequency of deltamethrin resistance (2,9%); and another with six populations (Campos dos Goytacazes, Ivinhema, Patos de Minas, Penápolis, Uberlândia, and Venda Nova) showing low to negligible levels of pyrethroid resistance (0,23%). The remaining seven populations, including a susceptible, and a DDT- and pyrethroid-resistant reference populations (Sete Lagoas and Jacarezinho, respectively), were significantly different from each other and from the two recognized clusters. In contrast with pyrethroid resistance, organophosphate resistance was negligible except for chlorpyrifos-methyl in two populations (Fátima do Sul and Penápolis). There was no correlation between geographic distance and the Mahalanobis distance estimated from the resistance pattern ordination of the populations by canonical variate analysis, suggesting local selection and/or broad dispersal of resistant populations by grain trade. The results of biochemical in vitro studies measuring the activity of detoxification enzymes (esterases and glutathion S -transferases) in conjunction with canonical correlation analysis suggest a major involvement of enhanced conjugation by glutathione S -transferases (> 2-fold increase) in pyrethroid resistance and, in the case of cypermethrin resistance, enhanced phosphotriesterase activity. [source] Frequencies of micronuclei in bank voles from zones of high radiation at Chornobyl, UkraineENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Brenda E. Rodgers Abstract A population of Clethrionomys glareolus (bank vole) from a highly radioactive area within the Chornobyl, Ukraine exclusion zone was sampled in June 1997 and in June and October 1998. Internal radiation doses from radiocesium were estimated to be as high as 8 rads/d. Total dose, which takes into account the internal dose from radiostrontium and the surrounding environment, was estimated to be 15 to 20 rads/d. In contrast, individuals from a reference population lying outside of the exclusion zone registered negligible levels of contamination. We used the micronucleus test in a double-blind study to analyze blood samples from 58 individuals. We scored more than 600,000 polychromatic erythrocytes (PCEs) but could not reject the null hypothesis that the frequency of micronucleated PCEs in voles exposed to radiation was equal to the frequency in unexposed voles. Results of our study stand in sharp contrast to earlier reports of increased frequencies of micronuclei in rodents exposed to fallout of the Chornobyl accident, but with radiation doses that were orders of magnitude lower than those reported here. Radioresistance and experimental methods are possible explanations for these differences in the results. [source] Modulation of oat arginine decarboxylase gene expression and genome organization in transgenic Trypanosoma cruzi epimastigotesFEBS JOURNAL, Issue 3 2006María P. Serra We have previously demonstrated that wild-type Trypanosoma cruzi epimastigotes lack arginine decarboxylase (ADC) enzymatic activity as well as its encoding gene. A foreign ADC has recently been expressed in T. cruzi after transformation with a recombinant plasmid containing the complete coding region of the oat ADC gene. In the present study, upon modulation of exogenous ADC expression, we found that ADC activity was detected early after transfection; subsequently it decreased to negligible levels between 2 and 3 weeks after electroporation and was again detected ,,4 weeks after electroporation. After this period, the ADC activity increased markedly and became expressed permanently. These changes of enzymatic activity showed a close correlation with the corresponding levels of ADC transcripts. To investigate whether the genome organization of the transgenic T. cruzi underwent any modification related to the expression of the heterologous gene, we performed PCR amplification assays, restriction mapping and pulse-field gel electrophoresis with DNA samples or chromosomes obtained from parasites collected at different time-points after transfection. The results indicated that the transforming plasmid remained as free episomes during the transient expression of the foreign gene. Afterwards, the free plasmid disappeared almost completely for several weeks and, finally, when the expression of the ADC gene became stable, two or more copies of the transforming plasmid arranged in tandem were integrated into a parasite chromosome (1.4 Mbp) bearing a ribosomal RNA locus. The sensitivity of transcription to ,-amanitin strongly suggests involvement of the protozoan RNA polymerase I in the transcription of the exogenous ADC gene. [source] Gillnet fishing drives lake-migrating brown trout to near extinction in the Lake Päijänne region, FinlandFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2010J. SYRJÄNEN Abstract, Wild stocks of brown trout, Salmo trutta L., collapsed in Finnish inland waters during the 20th Century because dams prevented upstream migration, and low water quality and stream dredging weakened reproduction. The demise in migratory stocks was coupled with overfishing, mainly by gillnetting on lakes. Consequently, the migratory spawning stocks have diminished to negligible levels. The remaining stocks exhibit restricted immigration and emigration, are supplemented by continuous stocking, and their natural genetic diversity is affected by human activities. In recent years, various recovery actions have been implemented including stream channel restorations, fish passage facilities constructed and stocking of eggs and smolts. Gillnetting has also been regulated by banning certain mesh sizes, and catch-and-release of wild trout is spreading amongst sport fishers. However, these measures seem to be inadequate and almost no recovery of migratory populations has been reported. The problem of by-catch in intensive gillnetting continues to threaten stocks and creates disputes between stakeholders. [source] Low-dose TNF-, protects against hepatic ischemia-reperfusion injury in mice: Implications for preconditioningHEPATOLOGY, Issue 1 2003Narci Teoh Tumor necrosis factor , (TNF-,) is implicated in the pathogenesis of hepatic ischemia reperfusion injury but can also prime hepatocytes to enter the cell cycle. Ischemic preconditioning protects against ischemia-reperfusion (IR) liver injury and is associated with activation of nuclear factor ,B (NF-,B) and cell cycle entry. We examined the pattern of TNF-, release during hepatic IR in the presence or absence of ischemic preconditioning, and we tested whether a single low-dose injection of TNF could mimic the biologic effects of ischemic preconditioning. In naïve mice, hepatic and plasma levels of TNF-, rose during hepatic ischemia, reaching high levels after 90 minutes; values remained elevated during reperfusion until 44 hours. Following the ischemic preconditioning stimulus, there was an early rise in hepatic and serum TNF-, levels, but, during a second prolonged ischemic interval peak, TNF-, values were lower than in naïve mice and declined to negligible levels by 2 hours reperfusion. An injection with 1 ,g or 5 ,g/kg body weight TNF-, 30 minutes prior to hepatic IR substantially reduced liver injury determined by liver histology and serum alanine aminotransferase (ALT) levels. As in ischemic preconditioning, TNF-, pretreatment activated NF-,B DNA binding, STAT3, cyclin D1, cyclin-dependent kinase 4 (cdk4) expression, and cell cycle entry, determined by proliferating cell nuclear antigen (PCNA) staining of hepatocyte nuclei. In conclusion, the hepatoprotective effects of "preconditioning" can be simulated by TNF-, injection, which has identical downstream effects on cell cycle entry. We propose that transient increases in TNF-, levels may substitute for, as well as, mediate the hepatoprotective effects of ischemic preconditioning against hepatic IR injury. [source] Fatty acid composition and volatile compounds of selected marine oils and mealsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2009Ioannis Giogios Abstract BACKGROUND: Although volatile compounds characterising seafood have been studied extensively, no similar data are available regarding the volatiles of raw materials used in fish feed. Therefore the aim of this study was to make an initial screening of the volatiles of various common marine raw materials used in the aquaculture feed industry. Nine commercial marine oils (German (GFO1, GFO2 and GFO3) and Norwegian (NFO) fish oils and salmon (SO1 and SO2), tuna (TO), sardine (SRDO) and shrimp (SHO) oils) and eight commercial marine meals (Peruvian (PFM1 and PFM2), Danish (DFM1 and DFM2) and prime quality (PQFM1 and PQFM2) fish meals and Antarctic krill meals (KM1 and KM2)) were analysed for their fatty acid profiles and volatile flavour compounds. The relation between fatty acids and volatiles was examined. RESULTS: The highest polyunsaturated fatty acid and eicosapentaenoic acid (20:5,3) contents and ,3/,6 ratio were found in NFO. The fatty acid composition of all marine meals except krill meals was found to be more variable among batches than that of marine oils. Regarding volatiles, all marine raw materials were characterised by the complete absence or negligible levels of eight- and nine-carbon alcohols and carbonyls. All marine oils were found to have high 2-ethyl furan, 2-methylenebutyl cyclopropane, hexanal, 2,4-octadiene and 3,5-octadiene contents. Marine meals, unlike marine oils, were characterised by the almost complete absence of unsaturated and cyclic hydrocarbons and terpenes and very low levels of furans. CONCLUSION: Volatiles of marine meals differ from those of marine oils. Unlike fatty acids which give useful traceability information, volatiles seem to fail in this role owing to their strong variability. Copyright © 2008 Society of Chemical Industry [source] Ceric Ammonium Nitrate Initiated Grafting of PEG to Plasma Polymers for Cell-Resistant SurfacesPLASMA PROCESSES AND POLYMERS, Issue 2 2008Naomi J. Vickers Abstract The development of a facile method with general applicability and mild reaction conditions for grafting PEG onto surfaces to reduce bio-adhesion is described. The approach taken was to use CAN to graft PEG to plasma polymers coatings selected to give a high concentration of alcohol groups. The study showed that grafting required functional groups on surfaces, a minimum concentration of CAN initiator (0.05 M) and was time and initiator concentration dependent. Adhesion of fibroblasts and endothelial cells was reduced to negligible levels compared to the adhesion to tissue culture polystyrene and untreated plasma polymers of allyl alcohol following CAN induced PEG grafting. [source] New blood for hemoglobin in the lens: roles in stem cell differentiation and fibre cell organelle loss?ACTA OPHTHALMOLOGICA, Issue 2008MA WRIDE Purpose Evidence is emerging for haemoglobin (Hb) expression outside the vascular system. We previously demonstrated Hb expression in the mouse lens during post-natal development and cataract progression. Here, we extended this work by carrying out a comprehensive spatio-temporal analysis of Hb subunit expression during mouse lens development and maturation. Methods We used RT-PCR, Western blotting and immunofluorescence to analyze Hb expression in mouse eyes (E16.5 to 9 wks). We also used a sensitive heme assay to test for the presence of heme in the lens by colourimetric assay and histological staining of paraffin-embedded sections. Results Hb subunits were expressed in lens epithelial cells and cortical lens fibre cells. However, the heme assay revealed negligible levels of this prosthetic group in the lens. Hb immunofluorescence was also observed in other regions of the developing eye including the cornea, the retinal ganglion cell layer and the retinal pigment epithelium. Finally, we also observed Hb expression in early embryos by microarray and during differentiation of embryonic stem (ES) cells into embryoid bodies (EBs) in vitro. Conclusion These results suggest a paradigm shift: Hb subunits are expressed in the eye during development and in the adult and, therefore, may have novel roles in ocular development, physiology and pathophysiology. The absence of heme from the lens indicates that at least some of these functions may be independent of oxygen metabolism. The pattern of expression of Hb in lens epithelial cells and cortical lens fibre cells may indicate an involvement for Hb subunits in lens epithelial cell differentiation into lens fibre cells and/or lens fibre cell organelle loss. [source] Salt fluoridation and dental caries in JamaicaCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 4 2001Saskia R. Estupiñán-Day Abstract ,Purpose: In 1987, Jamaica initiated a comprehensive island-wide salt fluoridation program. A survey was conducted in 1995 to monitor the impact of salt fluoridation among children in Jamaica. Methods: Dental examinations of 1120 children aged 6,8, 12, and 15 years were conducted according to World Health Organization criteria to assess dental caries, fluorosis, the presence of and need for dental sealants, and Community Periodontal Treatment Needs (CPI). Results: Age specific DMFT means observed in 1995 were 0.2 at age 7, 0.4 at age 8, 1.1 at age 12 and 3.0 at age 15. The mean DMFT scores in children 6, 12 and 15 years of age were dramatically lower than the corresponding scores of 1.7, 6.7 and 9.6 obtained at the baseline examination in 1984 for children of the same age groups, respectively (baseline data for 7- and 8-year-olds were not collected). The mean percentage of sound permanent teeth for all age groups was 90% in 1995. The percentage of children caries-free at baseline was 27.6% for 6 years, 2.8% for 12 years and 0.3% for 15 years of age. In 1995, the percentage of caries-free children (permanent teeth) was 61%. In 1984, 23 children were scored as having very mild or mild fluorosis. In 1995, five children were scored in the same categories of fluorosis, using Dean's criteria; thus, fluorosis remained at negligible levels in 1995. Conclusions: The oral health survey conducted in Jamaica in 1995 indicated a significant decline in dental caries compared with findings in 1984. The major change in Jamaica during the interval was the introduction of salt fluoridation in 1987. Dental fluorosis was low in the 1995 survey. [source] | ||||||||||||||||