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OTC Treatment (otc + treatment)
Selected AbstractsImpact of warming and timing of snow melt on soil microarthropod assemblages associated with Dryas- dominated plant communities on SvalbardECOGRAPHY, Issue 1 2006Rebecca Dollery Open Top Chambers (OTCs) were used to measure impacts of predicted global warming on the structure of the invertebrate community of a Dryas octopetala heath in West Spitsbergen. Results from the OTC experiment were compared with natural variation in invertebrate community structure along a snowmelt transect through similar vegetation up the adjacent hillside. Changes along this transect represent the natural response of the invertebrate community to progressively longer and potentially warmer and drier growing seasons. Using MANOVA, ANOVA, Linear Discriminant Analysis and ,2 tests, significant differences in community composition were found between OTCs and controls and among stations along the transect. Numbers of cryptostigmatic and predatory mites tended to be higher in the warmer OTC treatment but numbers of the aphid Acyrthosiphon svalbardicum, hymenopterous parasitoids, Symphyta larvae, and weevils were higher in control plots. Most Collembola, including Hypogastrura tullbergi, Lepidocyrtus lignorum and Isotoma anglicana, followed a similar trend to the aphid, but Folsomia bisetosa was more abundant in the OTC treatment. Trends along the transect showed clear parallels with the OTC experiment. However, mite species, particularly Diapterobates notatus, tended to increase in numbers under warming, with several species collectively increasing at the earlier exposed transect stations. Overall, the results suggest that the composition and structure of Arctic invertebrate communities associated with Dryas will change significantly under global warming. [source] The ameliorative effect of cysteine prodrug l -2-oxothiazolidine-4-carboxylic acid on cisplatin-induced nephrotoxicity in ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 5 2007B.H. Ali Abstract Pathogenesis of nephrotoxicity of the synthetic anticancer drug cisplatin (CP) involves generation of reactive oxygen species and free radicals in the kidney cortex, and cysteine prodrug l -2-oxothiazolidine-4-carboxylic acid (OTC) has been confirmed to have a strong antioxidant action. Therefore, in the present work, we aimed at testing the possible protective or palliative effect of OTC on CP nephrotoxicity in rats. OTC was given at an oral dose of 150 mg/kg/day for 7 days. On day 7, some of these rats were given a single intraperitoneal injection of CP (or vehicle) at a dose of 6 mg/kg. Rats were killed, blood and urine samples were collected, and the kidneys were removed 6 days after CP treatment. Nephrotoxicity was evaluated histopathologically by light microscopy, and biochemically by measuring the concentrations of creatinine and urea in serum, reduced glutathione (GSH) concentration and superoxide dismutase (SOD) activity in renal cortex, and by urinalyses. CP significantly increased the concentrations of urea and creatinine (P < 0.05) by about 128% and 170% respectively. CP treatment reduced cortical GSH concentration by about 34% (P < 0.05), and the activity of SOD by about 28% (P < 0.05). CP treatment significantly increased urine volume and N -acetyl- , - d -glucosaminidase (NAG) activity, and significantly decreased osmolality and protein concentrations. OTC significantly mitigated all these effects. Sections from saline- and OTC-treated rats showed apparently normal proximal tubules. However, kidneys of CP-treated rats had a moderate degree of necrosis. This appeared to be lessened when CP was given simultaneously with OTC. The concentration of CP in the cortical tissues was not significantly altered by OTC treatment. The results suggested that OTC had ameliorated the histopathological and biochemical indices of nephrotoxicity in rats. Pending further pharmacological and toxicological studies, OTC may potentially be useful as a nephroprotective agent. [source] Acute effects of the antibiotic oxytetracycline on the bacterial community of the grass shrimp, Palaemonetes pugio,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009Miguel Uyaguari Abstract The toxicity of oxytetracycline (OTC) was evaluated in adult grass shrimp, Palaemonetes pugio. Initially, static acute (96 h) toxicity tests were conducted with shrimp exposed from 0 to 1,000 mg/L OTC. A calculated lethal concentration 50% value of 683.30 mg/L OTC (95% confidence interval 610.85,764.40 mg/L) was determined from these tests, along with a lowest-observable-effect concentration of 750 mg/L and no-observable-effect concentration of 500 mg/L. Moreover, chronic sublethal effects of OTC exposure on grass shrimp intestinal bacterial population were assessed using doses from 0 to 32 mg/L OTC. The total viable counts in digestive tract content had levels between 5.2 and 1 × 104 colony-forming units per gram of tissue at times 0 and 96 h, respectively. Aeromonas hydrophila were the most resistant isolates (27.78%) to OTC exposure. Vibrio alginolyticus showed significant positive growth following exposure to OTC, whereas other bacterial species abundance declined over time. A total of 268 bacterial isolates were screened using antibiotic resistance analysis from a library containing 459 isolates. Among the tested isolates from the OTC treatments, 15.4% were resistant to OTC and 84.6% were OTC sensitive. Oxytetracycline was generally not consistently quantifiable with liquid chromatography-mass spectroscopy technique in shrimp homogenates. The only peak detected was at the 32 mg/L dose of OTC at 96 h. Nevertheless, OTC had a significant biological effect on the bacterial population. Antibiotic resistance to five other antibiotics (penicillin G, sulfathiazole, trimethoprim, trimethoprim and sulfamethoxazole, and tetracycline) was strongly associated with OTC exposures. The present study indicates that OTC toxicity effects in P. pugio and changes in the shrimp microbial community would only be expected under special circumstances. [source] | ||||||||||