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Little Degradation (little + degradation)
Selected AbstractsPotential for octylphenol to biodegrade in some english riversENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2000Andrew C. Johnson Abstract To study octylphenol biodegradation, samples of river water and sediments were taken from the Aire and Calderr vers in the United Kingdom, running through urban/industrial areas, as well as the Thames River running through a more rural area. Using laboratory microcosms, half-lives of 7 to 50 d were obtained for the water samples, with most curves fitting a zero-order reaction. The Calder River was sampled at four separate points along a 45-km length, encompassing rural to increasingly urban/industrial reaches. Little degradation was observed in the sample from the upland/rural reach, while half-lives of 8 to 13 d were seen in the more urban/industrial reaches. Mineralization of the phenyl ring, detected by evolution of 14CO2 from ring-labeled octylphenol, was only observed in water from the Calder River sample. Degradation rate was similar for a range of concentrations from 0.3 to 100 ,,g/L when tested with river water from the Thames River. No degradation was observed over 83 d when bed sediments were spiked with octylphenol and incubated under anaerobic conditions. [source] Intracellular trafficking and release of intact edible mushroom lectin from HT29 human colon cancer cellsFEBS JOURNAL, Issue 7 2000Lu-Gang Yu Our previous studies have shown that the Gal,1,3GalNAc,- (Thomsen,Friedenreich antigen)-binding lectin from the common edible mushroom Agaricus bisporus (ABL) reversibly inhibits cell proliferation, and this effect is a consequence of inhibition of nuclear localization sequence-dependent nuclear protein import after ABL internalization [Yu, L.G., Fernig, D.G., White, M.R.H., Spiller, D.G., Appleton, P., Evans, R.C., Grierson, I., Smith, J.A., Davies, H., Gerasimenko, O.V., Petersen, O.H., Milton, J.D. & Rhodes, J.M. (1999) J. Biol. Chem.274, 4890,4899]. Here, we have investigated further the intracellular trafficking and fate of ABL after internalization in HT29 human colon cancer cells. Internalization of 125I-ABL occurred within 30 min of the lectin being bound to the cell surface. Subcellular fractionation after pulse labelling of the cells with 125I-ABL for 2 h at 4 °C followed by culture of the cells at 37 °C demonstrated a steady increase in radioactivity in a crude nuclear extract. The radioactivity in this extract reached a maximum after 10 h and declined after 20 h. Release of ABL from the cell, after pulse labelling, was assessed using both fluorescein isothiocyanate-labelled ABL and 125I-ABL and was slow, with a t1/2 of 48 h. Most of the 125I-ABL both inside cells and in the medium remained intact, as determined by trichloroacetic acid precipitation and SDS/PAGE, and after 48 h only 22 ± 2% of ABL in the medium and 14 ± 2% inside the cells was degraded. This study suggests that the reversibility of the antiproliferative effect of ABL is associated with its release from cells after internalization. The internalization and subsequent slow release, with little degradation of ABL, reflects the tendency of lectins to resist biodegradation and implies that other endogenous or exogenous lectins may be processed in this way by intestinal epithelial cells. [source] The Dose-Response Effects of Ethanol on the Human Fetal Osteoblastic Cell LineJOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2001A. Maran Abstract Alcohol is a risk factor for the development of osteoporosis, especially in men. Chronic alcohol abuse decreases bone mass, which contributes to the increased incidence of fractures. To better understand the mechanism of action of ethanol on bone metabolism, we have studied the dose-response effects of ethanol on conditionally immortalized human fetal osteoblasts (hFOB) in culture. Ethanol treatment had no significant effects on osteoblast number after 1 day or 7 days. Ethanol treatment did not reduce type I collagen protein levels at either time point at any dose but slightly reduced alkaline phosphatase activity after 7 days. The messenger RNA (mRNA) levels for alkaline phosphatase, type I collagen, and osteonectin were unaltered by 24 h of ethanol treatment but a high dose (200 mM) reduced mRNA levels for the two bone matrix proteins after 7 days. Ethanol treatment led to dose-dependent increases in transforming growth factor ,1 (TGF-,1) mRNA levels and decreases in TGF-,2 mRNA levels. The concentration of ethanol in the medium decreased with time because of evaporation but there was little degradation caused by metabolism. These results, which show that cultured osteoblasts are less sensitive than osteoblasts in vivo, suggest that the pronounced inhibitory effects of ethanol on bone formation are not caused by direct cell toxicity. [source] Control of the impedance bandwidth of wideband planar monopole antennas using a beveling techniqueMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2001M. J. Ammann Abstract Wideband planar monopole antennas have recently been proposed for use on digital mobile terminals. The square planar monopole is the simplest to analyze, and suffers little degradation of radiation pattern within the impedance bandwidth. The addition of a bevel on one or both sides of the feed probe is shown to increase the bandwidth with good control of the upper edge frequency. The impedance bandwidth ratio for this antenna is shown to vary from 2:1 to 6:1, which can be controlled by beveling the planar geometry. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 229,232, 2001. [source] In vitro fermentability of human milk oligosaccharides by several strains of bifidobacteriaMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 11 2007Robert E. Ward Abstract This study was conducted to investigate the catabolism and fermentation of human milk oligosaccharides (HMO) by individual strains of bifidobacteria. Oligosaccharides were isolated from a pooled sample of human milk using solid-phase extraction, and then added to a growth medium as the sole source of fermentable carbohydrate. Of five strains of bifidobacteria tested (Bifidobacterium longum biovar infantis, Bifidobacterium bifidum, Bifidobacterium longum biovar longum, Bifidobacterium breve, and Bifidobacterium adolescentis), B. longum bv. infantis grew better, achieving triple the cell density then the other strains. B. bifidum did not reach a high cell density, yet generated free sialic acid, fucose and N-acetylglucosamine in the media, suggesting some capacity for HMO degradation. Thin layer chromatography profiles of spent fermentation broth suggests substantial degradation of oligosaccharides by B. longum bv. infantis, moderate degradation by B. bifidum and little degradation by other strains. While all strains were able to individually ferment two monosaccharide constituents of HMO, glucose and galactose, only B. longum bv. infantis and B. breve were able to ferment glucosamine, fucose and sialic acid. These results suggest that as a potential prebiotic, HMO may selectively promote the growth of certain bifidobacteria strains, and their catabolism may result in free monosaccharides in the colonic lumen. [source] Remedial options for chlorinated volatile organics in a partially anaerobic aquiferREMEDIATION, Issue 4 2004Xiujin Qiu A laboratory study was conducted for the selection of appropriate remedial technologies for a partially anaerobic aquifer contaminated with chlorinated volatile organics (VOCs). Evaluation of in situ bioremediation demonstrated that the addition of electron donors to anaerobic microcosms enhanced biological reductive dechlorination of tetrachloroethene (PCE), trichloroethene (TCE), and 1,1,1-trichloroethane (1,1,1-TCA) with half-lives of 20, 22, and 41 days, respectively. Nearly complete reductions of PCE, TCE, 1,1,1-TCA, and the derivative cis-dichloroethene were accompanied by a corresponding increase in chloride concentrations. Accumulation of vinyl chloride, ethene, and ethane was not observed; however, elevated levels of 14CO2 (from 14C-TCE spiked) were recovered, indicating the occurrence of anaerobic oxidation. In contrast, very little degradation of 1,2-dichloropropane (1,2-DCP) and 1,1-dichlorethane (1,1-DCA) was observed in the anaerobic microcosms, but nutrient addition enhanced their degradation in the aerobic biotic microcosms. The aerobic degradation half-lives for 1,2-DCP and 1,1-DCA were 63 and 56 days, respectively. Evaluation of in situ chemical oxidation (ISCO) demonstrated that chelate-modified Fenton's reagent was effective in degrading aqueous-phase PCE, TCE, 1,1,1-TCA, 1,2-DCP, etc.; however, this approach had minimal effects on solid-phase contaminants. The observed oxidant demand was 16 g-H2O2/L-groundwater. The oxidation reaction rates were not highly sensitive to the molar ratio of H2O2:Fe2+:citrate. A ratio of 60:1:1 resulted in slightly faster removal of chemicals of concern (COCs) than those of 12:1:1 and 300:1:1. This treatment resulted in increases in dissolved metals (Ca, Cr, Mg, K, and Mn) and a minor increase of vinyl chloride. Treatment with zero-valent iron (ZVI) resulted in complete dechlorination of PCE, and TCE to ethene and ethane. ZVI treatment reduced 1,1,1-TCA only to 1,1-DCA and chloroethane (CA) but had little effect on reducing the levels of 1,2-DCP, 1,1-DCA, and CA. The longevity test showed that one gram of 325-mesh iron powder was exhausted in reaction with > 22 mL of groundwater. The short life of ZVI may be a barrier to implementation. The ZVI surface reaction rates (ksa) were 1.2 × 10,2 Lm,2h,1, 2 × 10,3 Lm,2h,1, and 1.2 × 10,3 Lm,2h,1 for 1,1,1-TCA, TCE, and PCE, respectively. Based upon the results of this study, in situ bioremediation appeared to be more suitable than ISCO and ZVI for effectively treating the groundwater contamination at the site. © 2004 Wiley Periodicals, Inc. [source] | ||||||||||