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Day Exposure (day + exposure)
Selected AbstractsEffect of five diatomaceous earth formulations against Tribolium castaneum (Coleoptera: Tenebrionidae), Oryzaephilus surinamensis (Coleoptera: Silvanidae) and Rhyzopertha dominica (Coleoptera: Bostrychidae)INSECT SCIENCE, Issue 5 2007MASUMEH ZIAEE Abstract Laboratory bioassays were conducted to determine the effect of food source on the survival of Tribolium castaneum Herbst, Oryzaephilus surinamensis L. and Rhyzopertha dominica F., after exposure to five diatomaceous earth (DE) formulations: Protect-It®, Insecto®, Perma-GuardŌ, Dryacide® and SilicoSec®. Adults of these species were exposed to DEs at the rate of 0.5 mg/cm2 for 1 day on filter paper inside plastic Petri dishes. After exposure, the initial mortality was counted and live individuals of the three species were held for a week in glass vials containing 50 mg wheat flour, rice and whole wheat, respectively. In the second experiment, after 1 day exposure to DEs, beetles were transferred to Petri dishes without food and held for a week to determine if the presence of food source would decrease the mortality of beetles. Experiments were carried out at 27°C and 55% RH in the dark. The initial mortality in both of the experiments reached 100% for the three species exposed to Protect-It® and in the case of R. dominica and O. surinamensis exposed to Dryacide®. In contrast, low level of mortality (< 10%) was observed for T. castaneum exposed to Perma-GuardŌ and Insecto®. The mortality after the post-treatment period on food was decreased for the three species exposed to Perma-GuardŌ and in the case of T. castaneum and R. dominica exposed to Insecto® and SilicoSec®. Adults of O. surinamensis were the most susceptible followed by R. dominica and 100% adult mortality was obtained, whereas T. castaneum were the least susceptible beetles to DEs. Protect-It® and Dryacide® were the most efficient DE formulations and can be used effectively in a stored grain integrated pest management program. [source] Inhibition of Hematopoietic Progenitor Cell Proliferation by Ethanol in Human Immunodeficiency Virus Type 1 Tat-Expressing Transgenic MiceALCOHOLISM, Issue 3 2001Om Prakash Background: A number of hematological abnormalities are associated with both human immunodeficiency virus type 1 (HIV-1) infection and alcohol abuse. There is little information on how alcohol abuse might further influence the survival and growth of hematopoietic progenitors in HIV-infected individuals in the presence of immune system abnormalities and anti-HIV drugs. Because there is evidence that viral transactivator Tat itself can induce hematopoietic suppression, in this study we examined the role of ethanol as a cofactor in transgenic mice that expressed HIV-1 Tat protein. Methods: Tat transgenic mice and nontransgenic littermates were given ethanol (20% v/v) and the anti-HIV drug 3,-azido-3,-deoxythymidine (AZT; 1 mg/ml) in drinking water. Immunosuppression in mice was induced by weekly intraperitoneal injections of anti-CD4 antibody. Hematopoiesis was examined by erythroid colony forming unit (CFU-E) and granulocyte/macrophage colony-forming unit (CFU-GM) assays of the bone marrow progenitor cells. Results: Administration of ethanol for 7 weeks resulted in a 50% decrease in the proliferative capacity of CFU-E- and CFU-GM-derived progenitors from transgenic mice compared with that of ethanol-treated nontransgenic controls. Similar decreases also were observed in transgenic mice treated with AZT or a combination of AZT and ethanol. Furthermore, ethanol and AZT were significantly more toxic to the granulopoietic progenitors (40,50% inhibition) than to the erythropoietic progenitors (10,20% inhibition) in Tat transgenic mice. Although a 10 day exposure of Tat transgenic and nontransgenic mice to a combination of ethanol and AZT had no suppressive effect on the erythropoietic and granulopoietic progenitor cells, there was a marked decrease (40,60%) in CFU-GM in mice made immunodeficient by CD4+ T-lymphocyte depletion. The ethanol-treated Tat transgenic mice but not the nontransgenic littermates also showed a significant decrease (25%) in CFU-GM. Conclusion: Our in vivo study strongly suggests that ethanol ingestion in HIV-1-infected individuals, particularly those on antiretroviral drugs, might increase bone marrow toxicity and contribute to HIV-1-associated hematopoietic impairment. [source] Persistence and efficacy of two diatomaceous earth formulations and a mixture of diatomaceous earth with natural pyrethrum against Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) on wheat and maizePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2006Basileios J Vayias Abstract Laboratory tests were conducted to assess the insecticidal and residual effects of three diatomaceous earth (DE) formulations, Insecto®, PyriSec® and SilicoSec®, against Tribolium confusum Jacquelin du Val on wheat and maize. Quantities of wheat and maize were treated with the above formulations at 500, 1000 and 1500 mg kg,1 and stored at 25 °C and 55% relative humidity (RH). Samples were taken on the day of storage and every 30 days until completion of a 360 day period of storage. Adults of T. confusum were exposed to these samples at 25 °C and 55% RH and the mortality was measured after 24 and 48 h and 7 and 14 days of exposure. Adult mortality was higher on wheat than on maize. At the beginning of the storage period, mortalities after 14 day exposure on maize treated with the highest rate were 60, 63 and 81% for Insecto®, PyriSec® and SilicoSec® respectively, while on wheat the mortality was 100% for all DEs. On the same commodities 360 days after treatment the respective mortality figures for wheat were 99, 98 and 100%, while in the case of maize they did not exceed 7%. Generally, mortality at exposures ,48 h decreased with increasing storage time. Furthermore, although mortality on wheat increased with dose, the increase in DE dose from 1000 to 1500 mg kg,1 resulted in only a small increase in mortality. Thus a DE treatment of 1000 mg kg,1 was shown to provide long-term protection of wheat against T. confusum, although higher DE application rates and exposure intervals are needed for a satisfactory level of protection of maize against this pest. Copyright © 2006 Society of Chemical Industry [source] Plasma-lead concentration: Investigations into its usefulness for biological monitoring of occupational lead exposureAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2006Ingvar A. Bergdahl Abstract Background The lead concentration in plasma is correlated to that in whole blood with a two to fourfold variation. It has never been investigated if this variation is inter-individual. Methods Lead and hemoglobin were determined in blood and plasma from 13 lead workers with a history of relatively high blood-lead concentrations, sampled three times during 1 day. The variation in the distribution of lead between cells and plasma was studied, but not the variation in the lead concentrations as such. Results Blood hemoglobin decreased with rising plasma lead (0.9,3.0 µg/L). Regarding the distribution of lead, no effect of current exposure during the day or of recent meals appeared. As much as 84% of the overall variance of the distribution of lead between cells and plasma could be attributed to individual factors. After adjustment for erythrocyte volume fraction this decreased to 67%. Plasma samples with elevated hemoglobin concentrations (due to in vitro hemolysis) had somewhat elevated lead concentrations. Conclusions Plasma lead is not significantly altered by variation in a single day's exposure and, therefore, the choice of time of the day is not critical for sampling. However, plasma lead is negatively correlated to blood hemoglobin and mild hemolysis (not visible by the eye) in a sample may increase plasma lead with up to 30%. Finally, plasma provides lead exposure information that differs from whole blood, but it is not clear which one of these is the biomarker with the closest relation to exposure and/or effects. Am. J. Ind. Med. 49:93,101, 2006. © 2006 Wiley-Liss, Inc. [source] Trichophyton Mentagrophytes Perforates Hair of Adult Corpses in the Gaseous Period,JOURNAL OF FORENSIC SCIENCES, Issue 5 2010Renato Evando M. Filho M.S Abstract:, Despite the substantial literature on mycology, there are still limited reports of the interaction between fungi and human hosts in the postmortem period. Thus, the main goal of this study was to investigate the in vitro perforation test using Trichophyton mentagrophytes on hair from adult corpses in the postmortem period (gaseous period). The protocol was carried out with positive (prepubescent children's hair) and negative controls (healthy adult hair) as well. One strain of Trichophyton rubrum was also used as a negative perforation control. Perforations were found in all the hair samples from corpses and prepubescent children after 12,14 days exposure to T. mentagrophytes and were absent in the hair samples of healthy adults. Furthermore, hair perforation was not observed with T. rubrum. Our preliminary findings suggest the use of T. mentagrophytes as a potential marker of the death interval in forensic science. [source] Investigation into the effects of cidofovir on an in vitro model of recurrent respiratory papillomatosisCLINICAL OTOLARYNGOLOGY, Issue 3 2006A.J. Donne Problem. Recurrent respiratory papillomatosis (RRP) has no cure, and cidofovir is currently the most contemporary adjuvant treatment. Cidofovir has reported activity against Human Papilloma Virus type 16, but no laboratory studies have yet been performed on HPV type 6 which is the main cause of RRP. This work describes the generation of a novel HPV 6 related cell line and its use to evaluate the effects of Cidofovir. Method. HPV6b E6 cDNA was stably introduced into HPV negative C33A cervical carcinoma cells to produce the C33AT6E6 cell line. Two different doses of Cidofovir were applied to parent C33A, C33AT6E6 and C33AT16E6 (type 16 cell line) with appropriate controls. Growth and FACS cell cycle analysis were performed after 3 and 6 days of continuous exposure followed by 2 and 3 days post-drug withdrawal. Result.PCR analysis confirmed HPV6 E6 expression in C33AT6E6 cells. High dose cidofovir was toxic at 3 and 6 days exposure in all cells tested. Low dose exposure was toxic for C33AT16E6 cells at 3 days whereas C33A and C33AT6E6 only showed minimal toxicity at 6 days. C33A and C33AT6E6 cells also showed earlier recovery following drug withdrawal. Conclusion.Cidofovir showed varying degrees of non-specific toxicity against all three cell lines tested. However, HPV16 E6 expressing cells were more sensitive than either parent or HPV6 E6 expressing cells indicating that cidofovir has no selective advantage for the RRP related HPV6 E6 expressing cell line. [source] Cyst-based toxicity tests XIII,Development of a short chronic sediment toxicity test with the ostracod crustacean Heterocypris incongruens: Methodology and precisionENVIRONMENTAL TOXICOLOGY, Issue 6 2002Belgis Chial Abstract Experiments were carried out with neonates of the freshwater ostracod Heterocypris incongruens to verify and complete previous choices of test parameters for a new culture/maintenance-free solid-phase microbiotest for freshwater sediments. From trials with increasing volumes of reference sediment, it was concluded that 300 ,L was the most appropriate amount of substrate to be put in 12-cup multiwell plates with 2 mL of standard freshwater. Tests in 3,9 replicates eventually showed that six parallels were needed to have good assay precision (repeatability). Application of the final test protocol to oil-contaminated sediments from the St. Lawrence River in Canada revealed that the 6-day chronic ostracod microbiotest had less variation in repeated tests than did the 10-day contact assay with Hyalella azteca and hence can be considered more precise. Based on the 95% confidence intervals for mortality and growth of the ostracods in the controls (reference sediment) of the 56 tests carried out for the Canadian project, a validity threshold of 20% for mortality was eventually selected, in analogy with the acceptability limits applied in many chronic bioassays. A minimum length of 600 ,m in the control sediment after 6 days' exposure was also taken as the threshold for good health of the test organisms and for reliable test conditions. The new microbiotest has been tailored in a handy and user-friendly new toxkit, the Ostracodtoxkit, which is particularly suited for cost-effective routine monitoring. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 528,532, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10086 [source] | |||||||||||||