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Ochratoxins
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Josué Delgado, Miguel A. Asensio, Félix Núñez
Oxidative dechlorination by peroxidases would result in OTA-quinone or OTA-hydroquinone formation, but only trace amounts of OTA-hydroquinone have been reported.54 OTA-quinone seems to be detoxified in the liver, though only to a very limited extent, by conjugation with GSH, biotransformation into cysteinyl conjugates in the kidney, and then N-acetylation and excretion. Glucuronidation of ochratoxins has been shown in liver microsomes but not in hepatocytes, whereas pentose and hexose conjugates were detected in hepatocytes and in urine. Lactone-opened OTA was detected in the bile and urine of OTA-exposed rats, but the mechanism involved as well as its potential role in OTA detoxification still needs to be elucidated.
Pesticides and Chronic Diseases
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Dieldrin has not been thought to undergo appreciable metabolic degradation, but this notion may be erroneous. Oxidative dechlorination is now thought to occur.87 The average fat concentration in the general population in southern England was 0.21 mg/kg88 while the mean value in the United States was 0.14 mg/kg.89 Industry-exposed workers had an average fat concentration of 6.12 mg/kg.90
p, p′-DDE and HCB: Mechanisms of Toxicity to Fetal and Embryonic Mammalian Cells
Published in Rajesh K. Naz, Endocrine Disruptors, 2004
Michael A. Edelbrock, Martha J. Fernstrom, Kandace J. Williams
The metabolism of DDT is carried out through dechlorination and dehydro-cholorination, while DDE metabolism is by methylsulfonation events. A multi-step mechanism has been described based upon rodent studies using radioisotope labels.17,18 It has been proposed that DDD is first formed by dechlorination of DDT, followed by oxygenation and eventual formation of 2,2 bis(p-chlorophenyl)acetic acid (DDA). In vitro studies using rat liver microsomes have demonstrated a predominance of the metabolite DDD over DDE during DDT metabolism.19 While not all of the intermediate metabolites in these studies have been measured in humans, it has been presumed that the metabolic breakdown of DDT is similar to that found in rodents, with DDA the presumed endpoint for urinary elimination.3 These studies, and others, have raised several questions regarding the role of DDE during the metabolism of DDT. Although clearly associated with the metabolism of DDT, it appears that DDE does not play an essential role within the elimination pathway of DDT by the body. Further, formation of DDE from DDT may actually prolong xenobiotic removal, as further metabolism of DDE to an excretable alcohol or acetic acid derivative is not readily accomplished. Indeed, administration of DDT or DDD has been demonstrated to result in excretable DDA formation, whereas administration of DDE did not appreciably metabolize to DDA.3 This may indicate that DDE is not a predominant pathway of DDT metabolism, and therefore the deposition and presence of DDE in human tissues is evidence of an alternative and less-efficient metabolic pathway.
Membrane biofouling by chlorine resistant Bacillus spp.: effect of feedwater chlorination on bacteria and membrane biofouling
Published in Biofouling, 2018
Gopal Bhojani, Sweta Binod Kumar, Nirmal Kumar Saha, Soumya Haldar
Isolated bacteria with different morphologies were incubated in nutrient broth for 4 h with shaking. Subsequently, 25 μl of broth containing fresh bacterial culture were used to inoculate 2.5 ml of nutrient broth and in the next step, the same was exposed to sodium hypochlorite (purchased from Finar India Ltd., Ahmedabad, Gujarat, India) solution (0.5 ppm) for 0, 5, 10, 15, 20, 25 and 30 min for initial screening of chlorine resistant strains. After exposing to sodium hypochlorite solution for the specific time period, the broth was immediately dechlorinated using 1 ppm sodium metabisulphite (purchased from Finar India Ltd) solution. Samples of bacteria from the dechlorinated solution were then plated on nutrient agar and kept in an incubator at 37°C overnight. All experiments were conducted in triplicate. Free chlorine concentration and completeness of the dechlorination step were ensured colorimetrically using a MColortest (chlorine test kit) purchased from Merck Life Science Pvt Ltd., Bangalore, Karnataka, India. The chlorine test kit can measure chlorine in a free or combined state in the range 0.1 to 2.0 ppm with a colour scale graduation of 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0, 1.5 and 2.0. The bacteria which appeared on the nutrient plate were chlorine resistant; these were then isolated and preserved at –80°C until further analysis. For all the experiments other than the initial bacteria screening step, 25 μl of fresh bacterial culture were further inoculated in 2.5 ml of sterile chlorine free tap water. Tap water was chosen to nearly match the pretreated water quality (before chlorination) in the water treatment plant. Chlorination of water containing bacterial sample was carried out for 15 and 30 min only. Sodium hypochlorite solution, 0.5 ppm free chlorine, was used for chlorination.
Colonization and growth of dehalorespiring biofilms on carbonaceous sorptive amendments
Published in Biofouling, 2019
Staci L. Capozzi, Coline Bodenreider, Ana Prieto, Rayford B. Payne, Kevin R. Sowers, Birthe Veno Kjellerup
Biofilm growth was also examined via enumeration of the bacteria in the biofilm via qPCR. In all experiments, a larger fraction of the total number of bacteria was associated with the materials than the liquid (>99%). Therefore, the observed dechlorination was performed by DF1 in the biofilms. After 22 days, coal AC, bone BC, POM, and sand microcosms had dechlorinated 73%, 93%, 100%, and 83% respectively. Simultaneously, the abundance of DF1 bacterial cells in the biofilms increased for AC, BC, POM and sand throughout the experiment (Table 2).
Reducing free residual chlorine using four simple physical methods in drinking water: effect of different parameters, monitoring microbial regrowth of culturable heterotrophic bacteria, and kinetic and thermodynamic studies
Published in Toxin Reviews, 2021
Razieh Sheikhi, Amir Hossein Mahvi, Abbas Norouzian Baghani, Mahdi Hadi, Armin Sorooshian, Mahdieh Delikhoon, Somayeh Golbaz, Arash Dalvand, Fatemeh Johar, Mohammad Rezvani Ghalhari
In addition, free chlorine is also harmful to aquatic organisms and people who have aquariums that need water dechlorination to protect aquatic organisms (Roberts and Palmeiro 2008, Helfrich and Smith 2009, Demeke and Tassew 2016).