• 제목/요약/키워드: Lethal concentration

검색결과 253건 처리시간 0.021초

Synergistic Inhibition of Membrane ATPase and Cell Growth of Helicobacter pylori by ATPase Inhibitors

  • Ki, Mi-Ran;Yun, Soon-Kyu;Lim, Wang-Jin;Hong, Bum-Shik;Hwang, Se-Young
    • Journal of Microbiology and Biotechnology
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    • 제9권4호
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    • pp.414-421
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    • 1999
  • Helicobacter pylori were found to be resistant to azide but sensitive to vanadate, suggesting that defect in the P-type ATPase activity rather than F-type ATPase would be lethal to cell survival or growth. To elucidate the relationship between this enzyme inhibition and H. pylori death, we determined the effect of omeprazole (OMP) plus vanadate on enzyme activity and cell growth. The minimum inhibitory concentration (MIC; ca. 0.8$\mu$mol/disk) of vanadate for H. pylori growth was lowered over l0-fold with the aid of OMP, whereby its inhibitory potential toward the P-type ATPase activity was diametrically increased. Alternatively, we found that this enzyme activity was essential for active transport in H. pylori. From these observations, we strongly suggest that the immediate cause of the growth inhibition of H. pylori cells with OMP and/or vanadate might be defective in the cell's active transport due to the lack of P-type ATPase activity. From the spectral data with circular dichroism (CD) spectroscopy, we found that activated OMP (OAS) at concentration below MIC did not disrupt helical structures of membrane proteins. Separately, we determined the cytopathic effect of OAS by SDS-PAGE, indicating the change in the production of cytoplasmic protein but not cell membrane.

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탄화수소 누출로 인한 위험분석 평가 방법론 연구 (A Methodology for Assessing Risk from Released Hydrocarbon)

  • Keun-Won Lee
    • 한국안전학회지
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    • 제13권2호
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    • pp.170-180
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    • 1998
  • 본 연구는 밀폐된 지역에서 경험적 증발속도식을 사용하여 누출된 탄화수소의 농도 계산방법을 소개하였다. 그 접근방법은 가정된 조건하에서 공기중의 탄화수소 누출 농도를 추정하여 노출된 근로자나 사람의 개인적 위험평가를 위해 probit 표현식에 의한 위험평가 방법론을 제시하였다. 벤젠-공기 및 톨루엔-공기계에 대해 독성기준과 사람의 노출데이타가 조사되어졌고, 위험평가를 위한 가이드라인를 제시하였다. 탄화수소와 비독성 물질의 혼합물의 치사농도의 몰분율에 다른 probit 상수값들을 예측하였다. 몰분율에 따라 계산된 probit값은 밀폐된 작업구간에서 독성을 예방하기 위한 가이드라인을 추정하기 위해 사용될 수 있다.

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물벼룩을 이용한 bisphenol A의 급성독성 평가 (Acute Toxicity of Bisphenol A to the Crustacean Daphnia magna)

  • 황갑수
    • 한국환경보건학회지
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    • 제33권5호
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    • pp.392-396
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    • 2007
  • Aquatic ecotoxicity of bisphenol A, a well-known endocrine disrupter in mammals, was studied using laboratory-reared Daphnia magna as a test organism. The static acute 48 h $EC_{50}$ of bisphenol A for daphnid neonates(<24 hold) was 12.9 mg/l and 110 h $LC_{50}$ values of bisphenol A for daphnid embryos of different ages after deposition into the brood chamber increase with ages in the range of 1.55 mg/l-8.91 mg/l. Also, 48 h $EC_{50}s$ generally increase with daphnid's ages in the range of 12.9 mg/l-19.8 mg/l. In the acute toxicity tests using mature daphnids, the lethal response and immobility all showed good concentration-response relationship with exposure concentration and exposure time, showing little difference between lethality and immobility. These results clarify that acute toxicity tests, using daphnid and its embryo, could also be useful tools easily available for the assessment of ecotoxicity of various harmful chemicals.

Acute Toxicity of Heavy Metals, Tributyltin, Ammonia and Polycyclic Aromatic Hydrocarbons to Benthic Amphipod Grandidierella japonica

  • Lee, Jung-Suk;Lee, Kyu-Tae;Park, Gyung-Soo
    • Ocean Science Journal
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    • 제40권2호
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    • pp.61-66
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    • 2005
  • Benthic amphipod, Grandidierella japonica widely inhabits the Korean coastal waters and is developed as a standard test species for sediment toxicity tests. We exposed G. japonica to various pollutants including 4 kinds of inorganic metals (Ag, Cd, Cu and Hg), tributyltin [TBT], ammonia and 7 polycyclic aromatic hydrocarbon (PAH) compounds (acenaphthene, chrysene, fluoranthene, fluorene, naphthalene, phenanthrene and pyrene) to estimate the no observed effect concentration (NOEC) and the median lethal concentration (LC50) of each pollutant during the 96-hour acute exposure. Among all tested pollutants, TBT was most toxic to G. japonica, and Rg was most toxic among inorganic metals. The toxicity of pyrene to G. japonica was greatest among PAH compounds, followed by fluoranthene, phenanathrene, acenaphthene, fluorene and naphthalene. The toxicity of PAH compounds was closely related to their physico-chemical characteristics such as $K_ow$ and water solubility. G. japonica responded adequately to pollutant concentrations and exposure durations, and the sensitivity of G. japonica to various inorganic and organic pollutants was generally comparable to other amphipods used as standard test species in ecotoxicological studies, indicating this species can be applied in the assessment of environments polluted by various harmful substances.

Colorado Potato Beetle (Leptinotarsa decemlineata Say) Control Potential of Essential Oil Isolated from Iranian Cymbopogon citratus Stapf

  • Ebadollahi, Asgar;Geranmayeh, Jafar;Kamrani, Morteza
    • Natural Product Sciences
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    • 제23권4호
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    • pp.235-238
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    • 2017
  • Colorado potato beetle is a most destructive insect pest of potato throughout the world. Although utilization of chemical insecticides is a main method for management of this pest, their negative side-effects such as threat to humans and the environmental pollution prompted researchers to search for natural alternatives. Recently plant essential oils with low or without side-effects against noun-targeted organisms and with high availability were considered as safe bio-pesticides. In the present study, toxicity of essential oil of Iranian lemongrass, Cymbopogon citratus Stapf, was evaluated against 3th instar larvae and adults of Colorado potato beetle by a leaf dipping method. Results displayed essential oil had notable toxicity against both larvae and adults after 24 and 48 h exposure times. Probit analysis revealed $LC_{50}$ values (lethal concentration to kill 50% of population) with 95% confidence limits were 10.32 (9.17 - 11.72) and 7.76 (6.80 - 8.74) ${\mu}l/ml$ for larvae and 6.27 (4.82 - 8.15) and 4.35 (3.24 - 5.62) ${\mu}l/ml$ for adults after 24 and 48 h, respectively. Based on regression analysis, a positive correlation between log concentration of essential oil and insect mortality was achieved. Results indicated C. citratus essential oil can be candidate as a natural alternative to the harmful chemical insecticides in the management of Colorado potato beetle.

미세조류와 패류의 성장에 미치는 Triorganotin의 급성 독성영향 및 만성독성 실험을 위한 Chemostat System의 설계 (The Acute Toxicity Effect of Triotganotin on the Growth of Microalgae and Shellfish and A Design of A Chemostat System for the Chronic Toxicity Experiment)

  • 탁건태;이형호;홍용기;김중균
    • 생명과학회지
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    • 제7권4호
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    • pp.377-383
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    • 1997
  • The acute toxicity effect of triorganotin of trioganotin on the growth of microalgae and shellfish was investigated through flask culture. The value of 120 hr-LC$_{50}$ that is the median lethal concentration of TBTO on the shellfish (R. philipinarum) was found to be 6 $\mu$g/L. The acute toxicity effect of TBTO on T. suecica was obviously shown even at the concentration of 0.5 $\mu$g/L, and the effect diminished as the initial cell density increased. The effect also diminished less in the experiment done under aeration than in that done under non-aeration. To design a chemostat system for the test of chronic toxicity, the culture of T. suecica was executed in photobioreactor. In batch culture, the profiles of chlorophyII a and D.C.W. showed the growth of T. suecica very well, and the maximum specific growth rate was estimated to be 0.54 d$^{-1}$. with this value, as a dilution rate in contimuous culture, pH was nicely maintained between 7 and 9 when air was supplied with 3% CO$_{2}$. From all results and the natural environment of clam, a novel chemostat system was invented. Through this system, we can observe each independent toxicity effect of TBTO and plankton and combined toxicity effect as well.

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전자담배용 니코틴 원액 음독 후 발생한 심정지 1례 (A Case Report of Cardiac Arrest Following Intentional Ingestion of Liquid Nicotine for Electronic Cigarette)

  • 김정호
    • 대한임상독성학회지
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    • 제16권2호
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    • pp.172-175
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    • 2018
  • Acute nicotine poisoning by liquid nicotine for electronic cigarettes is becoming an increasing problem worldwide. On the other hand, there are no regulations regarding its concentration, container or labelling in Korea. This is the first case of a cardiac arrest after liquid nicotine ingestion that was confirmed by plasma nicotine detection in Korea. A 34-year-old male was found with a cardiac arrest at home by the emergency medical services crew, and had a return of spontaneous circulation after 27 minutes of cardio-pulmonary resuscitation. The cause of his cardiac arrest was suspected to be acute nicotine poisoning by the ingestion of liquid nicotine. Toxicology analysis of the National Forensic Service confirmed plasma nicotine, and the pharmacokinetic estimated average concentration of plasma nicotine at the time of the cardiac arrest was 29.7 mg/L, a lethal dose. He was hospitalized for further treatment, but was discharged after 20 days without any improvement. Considering the strong toxicity of nicotine, appropriate policy decisions are required for sales and distribution.

Comparison of Acute Toxicity of Different Groups of Pesticides to Honey Bee Workers(Apis Mellifera L.)

  • Ulziibayar, Delgermaa;Jung, Chuleui
    • 한국양봉학회지
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    • 제34권4호
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    • pp.305-313
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    • 2019
  • Honey bees (Apis mellifera) forage in agricultural areas, and are exposed to diverse pesticide poisoning. Toxic effects on Apis mellifera of different groups of pesticides were tested in the laboratory; fungicide (Metconazole), herbicide (Glyphosate), acaricide (Amitraz), organophosphate insecticide(Fenitrothion) and neonicotinoid insecticides(Thiacloprid, Thiamethoxam, Imidacloprid, Acetamiprid, Dinotefuran and Clothianidin). Commercial formulations were serially diluted from the recommended concentration (RC) to 10-6 times to carry out feeding and contact tests. Toxicity was transformed into lethal dose (LD50) and hazard question (HQ). The acute toxicity of pesticides showed similar patterns between feeding and contact tests. But feeding tests showed greater toxic to honey bee than contact test. The organophosphate and nitro-neonicotinoid insecticides were highly toxic with HQ values ranging greater than 1. However, cyano-neonicotinoids of Thiacloprid and Acetamiprid showed low toxicity. Even at the RC, 24 hr mortalities were 18 and 30%. The acaricide (Amitraz) showed intermediate level of toxicity at RC but negligible at the concentration lower than 10-1 times. A fungicide(Metconazole) and herbicide(Glyphosate) showed minimal impacts. The results imply that the selective use of pesticides could help conservation of pollinators in agricultural production systems.

해산어류 6종의 산소소비 경향에 관한 연구 (The Patterns of Oxygen Consumption In Six Species of Marine Fish)

  • KIM Il-Nam;CHANG Young-Jin;KWON Joon-Yeong
    • 한국수산과학회지
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    • 제28권3호
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    • pp.373-381
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    • 1995
  • 유용 해산어류에 대한 산소소비 경향을 파악하기 위하여 넙치 Paralichthys olivaceus, 자주복 Takifugu rubripes, 조피볼락 Sebastes schlegeli, 농어 Lateolabrax japonicus, 참돔 Pagrus major, 감성돔 Acanthopagrus schlegeli 등 6종의 추어를 주대상으로 수온별, 밀도별, 체중별 산소소비량및 치사산소량에 관한 실험을 실시하였다. 모든 어종에서 산소소비량 $(Oc,\;ml/kg\;\cdot\;hr)$은 수온$(T,\;^{\circ}C)$의 상승에 비례하여 증가하였으며, 그 경향은 다음과 같은 회귀직선식으로 표시되었다. 넙치= Oc=34.0515T-339.5987 $(r^2=0.9730)$, 자주복. Oc=34.4941T-479.8732 $(r^2=0.9483),$, 조피볼락: Oc=44.7970T-634.2627 $(r^2=0.9718),$, 농어: Oc=26.1488T-318.0633 $(r^2=0.9316),$, 참돔: Oc=61.1020T-722.8926 $(r^2= 0.9805),$, 감성돔: Oc=75.1460T-947.9370 $(r^2=0.9392).$. 어체의 수용밀도가 증가함에 따라 단위체중당 산소소비량은 감소하는 경향을 보였다. 넙치는 체중(W, g) 증가에 파라 산소소비량이 감소함으로써 Oc=2532.0268W-0.6565 $(r^2=0.9229)$의 관계를 나타냈다. 넙치, 조피볼락, 자주복, 참돔의 치사산소량은 각각 0.66, 0.79, 0.75 및 1.36m1/1였다

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Prediction of Acute Toxicity to Fathead Minnow by Local Model Based QSAR and Global QSAR Approaches

  • In, Young-Yong;Lee, Sung-Kwang;Kim, Pil-Je;No, Kyoung-Tai
    • Bulletin of the Korean Chemical Society
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    • 제33권2호
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    • pp.613-619
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    • 2012
  • We applied several machine learning methods for developing QSAR models for prediction of acute toxicity to fathead minnow. The multiple linear regression (MLR) and artificial neural network (ANN) method were applied to predict 96 h $LC_{50}$ (median lethal concentration) of 555 chemical compounds. Molecular descriptors based on 2D chemical structure were calculated by PreADMET program. The recursive partitioning (RP) model was used for grouping of mode of actions as reactive or narcosis, followed by MLR method of chemicals within the same mode of action. The MLR, ANN, and two RP-MLR models possessed correlation coefficients ($R^2$) as 0.553, 0.618, 0.632, and 0.605 on test set, respectively. The consensus model of ANN and two RP-MLR models was used as the best model on training set and showed good predictivity ($R^2$=0.663) on the test set.