Determination of Lethal Concentrations Using an R Software Function Integrating the Abbott Correction

Several thousands of chemical substances are registered every year for different purposes, and sometimes many of them are claimed to play the same role. To establish and compare their toxicities, the determination of the lethal concentrations is usually necessary and should account for natural mortality. However, many of the statistical software packages used for that purpose do not readily integrate control mortality or adjust the best link function to the data during the process. This manuscript proposes an ＂lc＂ function in the R open source that aims at the effective determination of lethal concentrations. Furthermore, it performs the procedure with the appropriate link function. The ＂lc＂ application on the example provided revealed that the complementary log link function is adequate.

Study of the Effectiveness of Papaver Sp. Alkaloids as Future Therapeutic Alternatives against Enterococcus Sp. Causing Hospital-Acquired Septicemic Infections

Background and Objective: In recent years, control of Enterococcus sp. It has been proven in the local medical environment to be a cause of acquired septicemia in various age groups, and medical instruments are considered an effective means of transmitting enterococcal septicemia, and catheters are at the forefront in terms of danger. Based on this risk, this study aimed to monitor the spread of Enterococcus sp., which causes blood poisoning acquired from catheters, and to compare its response to antibiotics with that of those isolated from clinical samples in children, as a first study locally. The effectiveness of alkaloids of different types of Papaver sp. In Syrian plants, they were tested against infection with this bacteria. Materials and Methods: The study dealt with two parts: The first part included collecting clinical samples from the University Children’s Hospital in Damascus/bacterial diagnostic laboratories/then isolating and diagnosing the bacteria by following a set of tests to identify the most prevalent genera and species and comparing their prevalence rate with Enterococcus. The second part;It included collecting plant samples, confirming the species taxonomically, then extracting alkaloids from plant parts (fruit, stem, Flowers), then comparing the extent of resistance of bacterial strains to antibiotics compared to the Enterococcus sp., and then confirming the antibacterial activity of the Papaver sp. alkaloids against Enterococcus sp. Result:In its first part, the study confirmed the significant contribution of the Enterococcus sp. to infections acquired from various sources, largely in catheter tip infections (9.09%) and to a lesser extent in other sources (3.7%), The second part was to confirm the effective-ness of the alkaloid extract of the Papaver sp., especially the two species Papaver syriacum, and Papaver dubium, against Enterococcus sp. with areole diameters that ranged between (15 - 26 mm) for the fruit extract and at a minimum inhibitory concentration (3.12 - 6.25 mml) and then the stem (5 - 20 mm). And the effectiveness of the Flowers extract is very weak to almost non-existent. Conclusions: The catheter and medical sources surrounding the patient constitute a dangerous source of multi-resistant Enterococcus sp., which poses a real threat to the lives of children, with new mechanisms represented by colonization of the skin and the ability to form biofilms Surfaces of medical instruments, with are resistant to a wide range of antibiotics. As an alternative and effective modern source to limit its spread in the future, the alkaloid extract of the fruits and stems of the wild Papaver sp. has proven a strong antibiotic effect, especially the two types: Papaver syriacum and Papaver dubium.

Resistance of Tribolium castaneum to Phosphine and the Relationship between Complete Lethal Concentration and Exposure Time of Phosphine in Hainan Province

[Objeetive] The paper was to investigate the resistance of Tribolium castaneum to phosphine in Hainan Province. [Method] Using the measurement method of phosphine resistance of stored grain pests recommended by FAO, the phosphine resistance of eight strains of T. castaneum adults in Hainan Province was determined. [Result] The resistance coefficients of different strains of ？7. castaneum against phosphine ranged from 612 to 1 045, and all strains reached extremely high resistance level （Rf〉 160）. When the concentration of phosphine was 200 mL/m^3, Rf612, Rf826.4 and Rfl 045 strains had complete lethal time of 8, 9 and 11 d, respectively. [Condusion] T. castarveum in Hainan Province had very strong resistance to phosphine, and the operation scheme of low concentration and long duration should be adopted in elimination of T. castaneum.

Study on the Acute Toxicity of Microsystin-LR on Hydra magnipapillata

[Objective] The research aimed to study the toxicity effect of microsystin on Hydra（aquatic animal model）.[Method] Hydra magnipapillata was as the experimental material.Under the different concentrations of MC-LR solution,its acute toxicity effect on Hydra magnipapillata was observed.[Result] The half lethal concentration（LC50） of MC-LR on Hydra magnipapillata at 24 h was 12.158,4.029 mg/L at 48 h and 1.799 mg/L at 72 h.[Conclusion] Hydra magnipapillata would die when treated by the low concentration of MC-LR solution.It illustrated that MC-LR produced by algal blooms caused the damage on some aquatic animals,and even some low-level aquatic animals died,such as Hydra magnipapillata and so on.The research provided some reference basis for the detection and assessment of water body pollution.

Probit Analysis of Carbamate-Pesticide-Toxicity at Soil-Water Interface to N_2-Fixing Cyanobacterium Cylindrospermum sp.

Toxicity-data of two carbamate insecticides, carbaryl and carbofuran, and three fungicides, ziram, zineb and mancozeb with rice-field N2-fixing cyanobacterium Cylindrospermum sp., obtained by in vitro growth and at soil-water interface, were analyzed by the probit method. Growth enhancing concentration, no-observed effective concentration, minimum inhibitory concentration, the highest permissive concentration and lethal concentration100 （LCloo） were determined experimentally. The LC^o values of carbaryl, carbofuran, ziram, zineb and mancozeb in N2-fixing liquid medium were 56.2, 588.8, 0.07, 4.2 and 3.4 IJg/mL, respectively, whereas the corresponding LCloo values were 100.0, 1500.0, 0.17, 25.0 and 9.0 IJg/mL, respectively. The LC50 values of these pesticides in succession in N2-fixing agar medium were 44.7, 239.9, 0.07, 1.8 and 2.3 IJg/mL, respectively, whereas the corresponding LC100 values were 100.0, 600.0, 0.17, 10.0 and 7.0 IJg/mL, respectively. Similar results with nitrate supplemented liquid and agar media indicated that nitrate supplementation had toxicity reducing effect. The LCso and LC^oo values of toxicity in the N2-fixing liquid medium at soil-water interface were 91.2 and 200.0 IJg/mL for carbaryl, 2 317 and 6 000 pg/mL for carbofuran, 0.15 and 0.50 pg/mL for ziram, 16.4 and 50.0 pg/mL for zineb, and 7.2 and 25.0 pg/mL for mancozeb, respectively. Each LC^oo value at soil- water interface with a pesticide was significantly higher than its corresponding LCloo value at liquid/agar media. It can be concluded that, under the N2-fixing conditions, the cyanobacterium tolerated higher levels of each pesticide at soil-water interface.

Extracts of the seaweed Bifurcaria bifurcata display antifungal activity against human dermatophyte fungi

Bifurcaria bifurcata is a seaweed of the Order Fucales(Ochrophyta,Phaeophyceae)that can be found all year round along the Portuguese Atlantic shore.Although it is considered edible in some countries,its biotechnological potential has not yet been assessed in detail and here we report its antimicrobial potential against human dermatophyte fungi.Three samples were harvested from Baleal Island(Peniche,Portugal)harvested in winter(BbPe);from Aguda Beach(Arcozelo,Vila Nova de Gaia,Portugal),harvested in autumn(BbAg)and a sample obtained by culturing the Aguda sample under laboratory conditions(BbLC).A broth macrodilution assay was applied to determine the MIC(minimum inhibitory concentration)and MLC(minimum lethal concentration)of the B.bifurcata extracts.Results show that the BbPe MeOH extracts were the most effective and had higher antifungal activity against all the tested dermatophyte strains than the BbLC and BaAg extracts[Epidermophyton floccosum FF9(100–200μg/mL MIC;200μg/mL MLC),Microsporum canis FF1(400μg/mL MIC;≥400μg/mL MLC),Trichophyton mentagrophytes FF7(100μg/mL MIC;>800μg/mL MLC),M.gypseum CECT 2908(800μg/mL MIC;≥800μg/mL MLC),T.mentagrophytes var.interdigitale CECT 2958(800μg/mL MIC;≥800μg/mL MLC),T.rubrum CECT 2794(200μg/mL MIC;≥400μg/mL MLC)].In fact,only E.floccosum FF9 was sensitive to BbAg and BbLC MeOH extracts.To our knowledge,this is the first report of antifungal activity of B.bifurcata against human dermatophyte fungi.

Effect of Water Hardness on the Toxicity of Cobalt and Nickel to a Freshwater Fish,Capoeta fusca

Objective To determine the effects of water hardness on the toxicities of cobalt （Co） and nickel （Ni） to a freshwater fish, Capoetafusca. Methods Toxicity was investigated by static bioassay. Fish were exposed to cobalt （as COCI2） and nickel （as NiCI2） for 96 h in waters with two levels of hardness （＂hard＂ and ＂very hard＂, nominally 130 mg/L and 350 mg/L as CaCO3, respectively）. Results Water hardness had a significant effect on the acute toxicity of both elements. The 96 h LC50 values for Co were 91.7 mg/L and 204.8 mg/L in hard and very hard waters, respectively, and for Ni the 96 h LC50 values were 78.0 mg/L and 127.2 mg/L, respectively. Conclusion The fish were more sensitive to Co and Ni toxicity in hard water than in very hard water; very hard water protects C. fusca against the toxicity of Co and Ni.

Toxic response of aquatic organisms to guide application of artemisinin sustained-release granule algaecide

In our previous study,we prepared the granules by embedding artemisinin into alginate-chitosan using microcapsule technology.These granules can release artemisinin sustainably and have a strong inhibitory effect on the growth of both single Microcystis aeruginosa and mixed algae.To safely and effectively use artemisinin sustained-release granules to control algal blooms,the ecotoxicity was studied by assessing their acute and chronic toxicity to Daphnia magna(D.magna)and Danio rerio(D.rerio),along with their antioxidant activities.The results showed that the 48-h median effective concentration(EC50)of pure artemisinin to D.magna was 24.54 mg/L and the 96-h median lethal concentration(LC50)of pure artemisinin to D.rerio was 68.08 mg/L.Both values were classified as intermediate toxicity according to the Organization for Economic Co-operation and Development(OECD).The optimal algae inhibitory concentration of artemisinin sustained-release granules(1 g/L)had low acute toxicity to both D.magna and D.rerio.The sustained-release granules had higher chronic toxicity to D.magna than to D.rerio.Partial indices of D.magna were inhibited by granules when the concentrations were larger than 0.1 g/L.Low granule concentration had an inductive effect on antioxidant enzyme activities in D.magna and D.rerio.With the increase of the exposure concentration and time,the enzyme activity presented a trend of first increasing and then decreasing,and the overall changes were significant.The change trend and range of enzyme activity indicated that the granules could cause serious oxidative stress to D.magna and D.rerio,and the changes were consistent with the results of toxicity experimentation.

Acute Toxicity of Formaldehyde to Eriocheir sinensis Zoea

The acute toxicities of formaldehyde to Chinese mitten crab(Eriocheir sinensis)zoea at various stages in semi-static system were studied.Each stage larvae was set with 5 concentration gradients and a contrast,and each concentration gradient had three parallels.The LC 50 of formaldehyde to Z1 was found to be 52.029 mg/L for 24 h and 29.300 mg/L for 48 h,with safety concentration of 2.79 mg/L;LC 50 to Z2 was 76.323 mg/L for 24 h,50.892 mg/L for 48 h,with safety concentration of 6.79 mg/L;LC 50 to Z3 was 108.947 mg/L for 24 h,67.693 mg/L for 48 h,with safety concentration of 7.84 mg/L;LC 50 to Z4 was 121.414 mg/L for 24 h,75.480 mg/L for 48 h,with safety concentration of 8.75 mg/L;LC 50 to Z5 was 128.546 mg/L for 24 h,89.312 mg/L for 48 h,with safety concentration of 12.934 mg/L.

Possible Synergistic Toxicity of Oxygen Scavenger and Defoamer on the Niger Delta Freshwater <i>Tilapia guineensis</i>

Globally, the generation of produced water keeps increasing due to depleting wells and about 40% of this wastewater is disposed of into the environment. Produced water is made up of several components that are toxic in nature, like production chemicals that are used for oil and gas production activities. Oxygen scavenger and defoamer are commonly used for corrosion prevention as both are applied at different stages of corrosion prevention. Evaluation of the possible synergistic toxicity contribution of oxygen scavenger and defoamer formed the basis of this research and was conducted using the Tilapia guineensis as bio-indicator. The toxicity test was carried out using the ELIMINOX (oxygen scavenger) and EC9017A (defoamer) individually and both chemicals were combined together. The choice of these chemicals was premised on previous researches that have confirmed that they are toxic individually, without further research on how they interact when they are combined. These chemicals and freshwater were used to generate produced water samples in the laboratory. The experiment was set up by adding ten fishes into each of the glass containers, containing the produced water samples at different concentrations and a control sample without the chemicals. The rate of mortality of the fish for the individual chemicals ranged from 100% to 10% for the different percentage concentrations. While on the other hand, a combination of the two chemicals had more survival than mortality, the percentage survival rate ranged from 100% to 90% across all the percentage concentrations. The lethal concentration also showed that the oxygen scavenger was more toxic than the defoamer, however, when they were combined;they showed an antagonistic relationship as the toxicity of the oxygen scavenger drastically reduced. The research findings intend to create awareness of the possible interaction of production chemicals when they are used for oil and gas activities and their combined toxicity contribution to produced water. This will in turn aid government regulators in their decision-making for disposal of produced water.

Toxicity of selected insecticides against nymph of whitefly （Bemisia tabaci Gennadius）

Bemisia tabaci is one of serious insect pests attacking vegetables and has been difficult to control using conventional insecticides. In the past 10 years, new insecticides have been introduced that provide a diversity of novel modes of action and routes of activity to effectively control whitefly. Consequently, intensive used of insecticides in vegetable cultivation has resulted in reduced susceptibility and develops resistance in agriculture industry. In controlling B. tabaci population, insecticides are the common method used by farmers. This study aimed to determine the most effective insecticide against B tabaci by using LC5o value. This study was conducted at the Crop Protection Laboratory, Faculty of Applied Science, Universiti Teknologi MARA Malaysia with the controlled room temperature of 24.33 ± 0.14℃ with dark and light ratio of 1：1 （12 hours： 12 hours） is an ideal condition for rearing the insect. The hypothesis of the study is to test if insecticides can control the nymph of whitefly. A total of 50 two-day-old nymphs were treated with insecticides using leaf-dip bioassay procedure. This experiment was replicated three times. The survival rates of the nymphs were analyzed using analysis of variance （ANOVA）. Data on toxicity was analyzed by a special Probit Programme-Single Line Analysis based on Finney （1971）. There was a significant difference （df = 8, F = 85.84, P = 0.000） in survival rate of nymph ofB. tabaci to eight insecticides tested. Among the insecticides tested, dimethoate, chlorpyrifos ＋ cypermethrin and diafenthiuron showed significantly higher survival rate of nymph compared to other treatments. When LC50 values were compared for diafenthiuron which is less potent （LCs0 ---- 2.44）, abamectin was found to be 3.44 times more potent than diafenthiuron, followed by esfenvalerate,acetamiprid, profenofos, chlorpyrifos ＋ cypermethrin and dimethoate, and the least potent was deltamethrin. The toxicity of eight insecticides tested against nymphs was in the following orders： abamectin = esfenvalerate = acetamiprid = profenofos =- chlorpyrifos ＋ cypermethrin ≥ dimethoate ≥ deltamethrin 〉 diafenthiuron respectively. This study implies that a proper application of the insecticide is a key component to a successful control programme of insect oests.

Effects of total dissolved gas supersaturated water on lethality and catalase activity of Chinese sucker(Myxocyprinus asiaticus Bleeker)

Total dissolved gas(TDG) supersaturation caused by dam sluicing can result in gas bubble trauma(GBT) in fish and threaten their survival.In the present study,Chinese suckers(Myxocyprinus asiaticus Bleeker) were exposed to TDG supersaturated water at levels ranging from 120% to 145% for 48 h.The median lethal concentration(LC 50) and the median lethal time(LT 50) were determined to evaluate acute lethal effects on Chinese suckers.The results showed that the LC 50 values of 4,6,8,and 10 h were 142%,137%,135%,and 130%,respectively.The LT 50 values were 3.2,4.7,7.8,9.2,and 43.4 h,respectively,when TDG supersaturated levels were 145%,140%,135%,130%,and 125%.Furthermore,the biological responses in Chinese suckers were studied by assaying the catalase(CAT) activities in gills and muscles at the supersaturation level of 140% within LT 50.The CAT activities in the gills and muscle tissues exhibited a regularity of a decrease after an increase.CAT activities in the muscles were increased significantly at 3/5LT 50(P<0.05) and then came back to the normal level.However,there were no significant differences between the treatment group(TDG level of 140%) and the control group(TDG level of 100%) on CAT activities in the gills before 3/5LT 50(P>0.05),but the activities were significantly lower than the normal level at 4/5LT 50 and LT 50(P<0.05).

Determination of the mechanism of photoinduced toxicity of selected metal oxide nanoparticles(ZnO,CuO,Co_3O_4 and TiO_2)to E.coli bacteria

Cytotoxicity of selected metal oxide nanoparticles（MNPs）（ZnO,CuO,Co 3 O 4 and TiO 2）was investigated in Escherichia coli both under light and dark conditions.Cytotoxicity experiments were conducted with spread plate counting and the LC 50 values were calculated.We determined the mechanism of toxicity via measurements of oxidative stress,reduced glutathione,lipid peroxidation,and metal ions.The overall ranking of the LC 50 values was in the order of ZnO 〈 CuO 〈 Co 3 O 4 〈 TiO 2 under dark condition and ZnO 〈 CuO 〈 TiO 2 〈 Co 3 O 4 under light condition.ZnO MNPs were the most toxic among the tested nanoparticles.Our results indicate depletion of reduced glutathione level and elevation of malondialdehyde level correlated with the increase in oxidative stress.Released metal ions were found to have partial effect on the toxicity of MNPs to E.coli.In summary,the dynamic interactions of multiple mechanisms lead to the toxicity of the tested MNPs to E.coli.

Effect of humic acids and sunlight on the cytotoxicity of engineered zinc oxide and titanium dioxide nanoparticles to a river bacterial assemblage

The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA （10 and 40 ppm） on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight （light irradiation （LI））. The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments： HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.