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PubMed1977

[The action of selected herbicides on bacteriophages and Escherichia coli (author's transl)].

The effect of eight herbicides on the multiplication of bacteria and bacteriophages was tested with Escherichia coli, strains W1665F+ and C600, and with the RNA-phage M12 and the DNA-phage lambda in turbidimetric investigations and one-step growth experiments. E. coli is inhibited by seven of the herbicides investigated in concentrations of 10(-3)M, partly of 10(-4)M, too, and is promoted by some compounds in weaker concentrations. Naphthylacetic acid, (NES) largely independent of its concentration, causes increased density of bacteria in fluid culture. The multiplication of the M12 phage is inhibited in sometimes wide ranges of concentration by 2,4-D, MCPA, 2,4-DP, and CMPP but it is stimulated by NES and amitrole. The lambda-phage multiplication is inhibited only by CMPP, MCPA, MCPB, and phenylacetic acid interfere with the lysogenization of the bacteria and increase the lytic activity of the lambda-phages as 2,4-DP and NES do. 2,4-D strongly inhibits the plaque-forming ability of M12 phages already prior to their contact with the host cells, whereas MCPA and CMPP are inhibitory in the first phases and 2,4-DP in all phases of the phage replication. In the lambda-phage replication, too, CMPP is effective only in the first phases. Aspects of the mode of action of the herbicides in the procaryoute virus system are discussed.

Cell Division↗
PubMed1979

Herbicide contamination and decontamination of well waters in Ontario, Canada, 1969-78.

OVER THE 10-YEAR period 1969-78, the waters of 237 wells were analyzed because of contamination from herbicide spillage in or near the well, complaints of impaired water flavor, or injury to seedling plants moistened with the well water. Herbicides were identified in 159 wells: 98 had a single herbicide, 46 had two, 12 had three, one had four, and another had five separate herbicides contributing to the contamination. Wells were grouped according to the mode of entry of the contaminant. Entry occurred most commonly as an aerial spray fdrift or in runoff. Serious contaminations were caused by spillage of herbicide concentrates and spray solutions in or around the well. Twenty-four of the contaminated wells were further investigated to determine the persistence of the contaminant and how to remove it. Some wells were decontaminated adequately to allow reuse within nine weeks, others required three years, and yet others had to be abandoned. Particularly persistent contaminants were amitrole, dinoseb, and picloram.

Herbicides↗
PubMedDate not supplied

Herbicidal treatments for control of Cannabis sativa L.

In order to test herbicides for the destruction of illicit stands of cannabis (Cannabis sativa L.) a series of commercially available herbicides were sprayed on glasshouse-grown plants having 2 to 6 leaves. The following herbicides caused complete kill or severe injury to cannabis plants: (a) herbicides with root and foliage activity--ametryn, atrazine, metribuzin, prometryn, terbutryne, diuron, fluometuron, linuron, methabenzthiazuron, phenobenzuron, ethofumesate, karbutilate, methazole and oxadiazon; and (b) foliar-acting herbicides with brief or no soil persistence--amitrole, bentazon, 2,4-D, diquat + paraquat, glyphosate and phenmedipham. In field experiments herbicides of the latter group, and ioxynil, metribuzin, and a MSMA-cacodylate mixture, caused death or severe damage to young cannabis plants. Glyphosate, ioxynil and bentazon destroyed developed cannabis plants. In glasshouse and field experiments the following herbicides applied to young cannabis plants caused marked deformations of stems, leaves and/or inflorescences: barban, butralin, dalapon, difenzoquat, dinitramine, diphenamid, IPC, napropamide, penoxalin, triffuralin, and U-27267.

Cannabis↗
PubMedDate not supplied

Absorption of aerosolized drugs from the rat lung.

To investigate the absorption of aerosolized drugs from the rat lung, anesthetized animals were allowed to inhale through a tracheal cannula liquid aerosols of drug solutions generated with an air-jet nebulizer. The aerosols had a mass median aerodynamic diameter of 2.81 +/- 0.08 micron and a geometric standard deviation of 2.53 +/- 0.05. At various times after aerosol inhalation, the lungs were removed and assayed for the amount of compound that had not been absorbed. The times (min) necessary for 50% absorption were: antipyrine, 0.25; salicylic acid, 0.67; barbital, 0.93; amitrole, 1.3; urea, 1.4; procainamide, 2.3; guanidine, 3.1; erythromycin, 6.3; benzylpenicillin, 20.5; p-aminohippuric acid, 21.7; mannitol, 26.5; and N-acetylprocainamide ethobromide, 34.5. Comparison with previously reported absorption rates measured after intratracheal injection of 0.1 ml of drug solution showed that drug inhaled as an aerosol was absorbed roughly two times more rapidly than when administered by intratracheal injection. The results suggest that drug absorption may be more rapid from the alveolar region than from the tracheobronchial region of the lung.

Absorption↗
PubMed1980

Herbicidal treatments for control of Papaver somniferum L.

Fifty-five commercially available herbicides were evaluated for possible use to destroy illicit opium poppy crops (Papaver somniferum). In the first stage, herbicides were sprayed on poppy plants grown in containers. The following compounds killed poppy plants: (a) herbicides with typical foliar activity--amitrole, bromoxynil, 2,4-D, glyphosate, ioxynil and paraquat; and (b) herbicides with root and foliar activity--the triazines ametryn, atrazine, metribuzin, prometryn, simazine and terbutryn; the substituted ureas benzthiazuron, chloroxuron, diuron, fluometuron, linuron, methabenzthiazuron, neburon and phenobenzuron; and the miscellaneous compounds karbutilate, methazole, oxadiazon and pyrazon. Severe but sublethal injury was caused by cycloate, EPTC, molinate, pobulate, cacodylate + MSMA, ethofumesate, perfluidone and phenmedipham. Abnormal development of vegetative or reproductive parts of the plant was induced by benefin, butralin, dinitramine, pendimethalin, trifluralin, diphenamid, napropamide, dalapon and propham. Efficient herbicides with negligible persistence in soil at the doses applied were evaluated on poppy plants in the field at various stages of growth. Small plants were severely injured by 2,4-D, killed rapidly by bromoxynil, ioxynil, paraquat (in mixture + diquat), and more slowly by glyphosate and metribuzin. The resistance to herbicides increased with the age of the poppy plant. Severe damage with partial kill of developed plants was obtained with bromoxynil, ioxynil, glyphosate, and paraquat + diquat; the last treatment produced the fastest effect.

Drug and Narcotic Control↗
PubMed1999

Decapping of stabilized, polyadenylated mRNA in yeast pab1 mutants.

Interaction of the poly(A) binding protein, Pab1p, with mRNA plays an important role in gene expression. This work describes an analysis of pab1 mutants in Saccharomyces cerevisiae. Yeast pab1 mutants were found to be sensitive to elevated concentrations of copper (Cu) and 3-aminotriazole (3-AT) in the growth medium. This phenotype arises because these pab1 mutants underaccumulate mRNA, including the CUP1 and HIS3 mRNAs, the products of which are required for Cu and 3-AT resistance, respectively. To determine the cause of the mRNA underaccumulation, mRNA turnover and production were examined in the pab1-53 mutant. It was found that although the pattern of mRNA decay was altered, and substantial decapping of polyadenylated mRNA could be detected, mRNA was not destabilized in this strain. It was also found that the pab1 mutant was impaired in the production of mRNA. These data show that the decreased level of mRNA in the pab1-53 mutant arises from poor production, and they suggest that yeast Pab1p is involved in an aspect of nuclear mRNA metabolism. They also indicate that deadenylation can be uncoupled from decapping without significant changes in an mRNA's stability, and that this uncoupling can be tolerated by yeast.

Amitrole↗
PubMed1998

Increase of reactive oxygen species (ROS) in endothelial cells by shear flow and involvement of ROS in shear-induced c-fos expression.

Intracellular reactive oxygen species (ROS) may participate in cellular responses to various stimuli including hemodynamic forces and act as signal transduction messengers. Human umbilical vein endothelial cells (ECs) were subjected to laminar shear flow with shear stress of 15, 25, or 40 dynes/cm2 in a parallel plate flow chamber to demonstrate the potential role of ROS in shear-induced cellular response. The use of 2',7'-dichlorofluorescin diacetate (DCFH-DA) to measure ROS levels in ECs indicated that shear flow for 15 minutes resulted in a 0.5- to 1.5-fold increase in intracellular ROS. The levels remained elevated under shear flow conditions for 2 hours when compared to unsheared controls. The shear-induced elevation of ROS was blocked by either antioxidant N-acetyl-cysteine (NAC) or catalase. An iron chelator, deferoxamine mesylate, also significantly reduced the ROS elevation. A similar inhibitory effect was seen with a hydroxyl radical (.OH) scavenger, 1,3-dimethyl-2-thiourea (DMTU), suggesting that hydrogen peroxide (H202), .OH, and possibly other ROS molecules in ECs were modulated by shear flow. Concomitantly, a 1.3-fold increase of decomposition of exogenously added H2O2 was observed in extracts from ECs sheared for 60 minutes. This antioxidant activity, abolished by a catalase inhibitor (3-amino-1,2,4-triazole), was primarily due to the catalase. The effect of ROS on intracellular events was examined in c-fos gene expression which was previously shown to be shear inducible. Decreasing ROS levels by antioxidant (NAC or catalase) significantly reduced the induction of c-fos expression in sheared ECs. We demonstrate for the first time that shear force can modulate intracellular ROS levels and antioxidant activity in ECs. Furthermore, the ROS generation is involved in mediating shear-induced c-fos expression. Our study illustrates the importance of ROS in the response and adaptation of ECs to shear flow.

Acetylcysteine↗
PubMed2000

Evaluation of the developmental toxicity of thalidomide using frog embryo teratogenesis assay-xenopus (FETAX): biotransformation and detoxification.

The developmental toxicity of thalidomide was evaluated using FETAX (Frog Embryo Teratogenesis Assay - Xenopus). Young X. Laevis embryos were exposed to this compound in each of two concentration-response experiments with and without differently induced exogenous metabolic activation systems (MASs) and/or inhibited MASs. Young male Sprague-Dawley rats were treated with either isoniazid or Aroclor 1254 to induce cytochrome P-450. Several of the rats were subsequently treated with diethyl maleate (DM) to deplete glutathione reserves. Specific aliquots of rat liver microsomes were treated with 3-amino-1,2,4-triazole (ATZ) or alpha-napthoflavone (alpha-N) to selectively inhibit P-450 activity. Bioactivation was indicated by increased developmental toxicity observed in MAS tests. Results obtained indicated that thalidomide was predominantly activated by P-450 isozyne CYP2E1, although weak cross-specificity between CYP1A1/A2 may have existed. Detoxification pathways for thalidomide were investigated by treatment of the MAS with cyclohexene oxide (CHO) and DM to inhibit the epoxide hydrolase and glutathione conjugation pathways, respectively. Results indicated that epoxide hydrolase was primarily responsible for the detoxification of bioactivated thalidomide. Teratogenesis Carcinog. Mutagen. 20:35-47, 2000.

Amitrole↗
PubMed2001

Expression and prognostic significance of catalase in malignant mesothelioma.

BACKGROUND: Free radicals and antioxidant enzymes (AOEs) may play a critical role in cell proliferation and in the resistance of malignant cells against cytotoxic drugs and radiation. Malignant mesothelioma is a resistant tumor with high levels of manganese superoxide dismutase, a central superoxide scavenging AOE. In the current study, the authors assessed the expression and prognostic role of catalase, an important hydrogen peroxide scavenging AOE, in malignant pleural mesothelioma. METHODS: Catalase expression was investigated by immunohistochemistry in 5 cases of nonmalignant healthy pleura and in tumor tissue of 32 mesothelioma patients, and by Western blot in 7 continuous human mesothelioma cell lines. The distribution of catalase in mesothelioma cells was assessed by immunoelectron microscopy. Furthermore, to investigate the effect of catalase inhibition in the drug resistance of these cells in vitro, the authors exposed mesothelioma cells with the highest catalase level to epirubicin with and without aminotriazole pretreatment. RESULTS: Nonmalignant mesothelial cells showed no catalase immunoreactivity whereas most mesothelioma cases (24 of 32, 75%) were catalase positive, 17 cases (53%) showing moderate or high expression. Higher catalase expression in mesothelioma was associated with a better prognosis, mean survival rate from diagnosis being 6 and 24 months for negative/low expression and moderate/high expression, respectively. Furthermore, a coordinately high expression of both manganese-superoxide dismutase (Mn-SOD) and catalase predicted even more favorable outcome of the mesothelioma patients. Catalase also could be detected in all mesothelioma cell lines, the most resistant cell line showing the highest protein expression and compartmentalization of catalase mainly to peroxisomes. Aminotriazole inhibition of catalase had a marginal effect on the toxicity caused by epirubicin. CONCLUSIONS: Catalase may have multifactorial effects in malignant cells; high catalase and/or coordinated high expression of Mn-SOD and catalase may decrease tumor progression by modulating the cellular redox state, but enhanced antioxidant capacity of mesothelioma cells also may protect tumor cells against exogenous oxidants, at least in vitro.

Amitrole↗
PubMed2001

Hydrogen peroxide detoxification in the midgut of the blood-sucking insect, Rhodnius prolixus.

Here we investigated H2O2 production and detoxification in the hematophagous hemiptera, Rhodnius prolixus. Superoxide dismutase (SOD) catalyzes the dismutation of superoxide radical (O2-). This reaction produces hydrogen peroxide, which is scavenged by antioxidant enzymes such as catalase (CAT). SOD and CAT activities were found in all tissues studied, being highest in the midgut. CAT was dose-dependently inhibited in vivo by injections of 3-amino-1,2,4-triazole (AT). Insects treated with AT showed a twofold increase in H2O2 levels. Injection of DL-buthionine-[S, R]-sulfoximine (BSO), an inhibitor of glutathione synthesis, also resulted in a fourfold increase in H2O2, together with stimulation of CAT activity. Simultaneous administration of both AT and BSO had a synergistic effect on midgut H2O2 content. Taken all together, our results suggest that CAT and glutathione-dependent mechanisms cooperate to control H2O2 concentration in the midgut cell and prevent hydroxyl radical generation by Fenton reaction in this tissue.

Amitrole↗
PubMed1987

Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay to coded chemicals. I: Results for nine compounds.

Nine substances were tested for their mutagenic potential in the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay, by means of procedures based upon those described by Clive and Spector (Mutat Res 44:269-278, 1975) and Clive et al (Mutat Res 59:61-108, 1979). Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before plating in soft agar with or without trifluorothymidine (TFT), 3 micrograms/ml. The coded chemicals were tested at least twice. Significant responses were obtained with calcium chromate, 3-(chloromethyl)pyridine, 1,2-epoxybutane, monochloroacetic acid, dicyclohexylthiourea, 2,4-diaminophenol hydrochloride, and pentachloroanisole. Apart from pentachloroanisole, rat liver S9 mix was not a requirement for the clearly mutagenic activity of any of these compounds. Compounds not identified as mutagens were 3-amino-1,2,4-triazole and sucrose.

Acetates↗
PubMed1983

Whole body and liver distribution of inhaled mercury vapor in the mouse: influence of ethanol and aminotriazole pretreatment.

Inhalation of radioactive metallic mercury vapor (203Hg0) in the mouse resulted in an accumulation of mercury in several organs where no specific uptake was observed after i.v. injection of inorganic mercury (203Hg2+). This was true for the whole respiratory epithelium (including the lung parenchyma), myocardium, brain, retina of the eye, adrenal cortex, corpora lutea of the ovary, epididymis, brown fat and thyroid gland. It is assumed that these organs have a high capacity for oxidizing Hg0 to Hg2+, which will then be retained in the tissues. Ethanol and aminotriazole (catalase inhibitors) decreased the concentration in several of these organs, although not in an exactly similar pattern. In the livers of non-treated animals, most of the inhaled mercury accumulated in the hepatocytes in the periphery of the lobuli (periportal region), close to where the blood vessels enter the liver parenchyma. Treatment with ethanol or aminotriazole increased the liver mercury content, with more or less all the hepatocytes apparently engaged in the oxidation of Hg0.

Amitrole↗
PubMed2002

Protection against acetaminophen hepatotoxicity by clofibrate pretreatment: role of catalase induction.

Mice pretreated with the peroxisome proliferator clofibrate (CFB) are highly resistant to acetaminophen (APAP)-induced hepatotoxicity. The objective of the present study was to investigate whether the increase in hepatic catalase activity following CFB pretreatment plays a role in this hepatoprotection. An irreversible inhibitor, 3-amino-1,2,4-triazole (3-AT), was used to modulate catalase activity. Hepatic catalase activity in mice pretreated with CFB (500 mg/kg, i.p., for 10 days) was significantly inhibited by 3-AT (100 or 500 mg/kg, i.p.). In addition, the lower dose of 3-AT (100 mg/kg) had minimal effect on biliary and urinary excretion of APAP metabolites generated from a nontoxic dose, suggesting that APAP metabolism was not modulated by this dose of 3-AT. The mortality rate of corn-oil-pretreated mice challenged with APAP (800 mg/kg, p.o.) was significantly increased by 3-AT (100 mg/kg, i.p.) given 1 h before APAP. As expected, CFB pretreatment conferred full protection against APAP-induced hepatotoxicity. The same 3-AT treatment, however, did not abolish hepatoprotection in CFB-pretreated mice, despite the marked inhibition of hepatic catalase activity. In conclusion, these results indicate that elevated catalase activity in mice exposed to CFB does not appear to mediate the hepatoprotection, suggesting that other cellular defense mechanisms are involved.

Acetaminophen↗
PubMed1986

An examination of the oxidation of mercury vapor by rat brain homogenate.

The oxidation of mercury vapor (Hg degrees) to divalent inorganic mercury (Hg2+) was studied in rat brain homogenates. By using a "degassing" method, it was possible to speciate the mercury present in the homogenate and, for the first time, to measure the rate of oxidation as a function of the substrate (Hg degrees) concentration. Mercury oxidation was first-order with respect to substrate concentration at all concentrations tested, and the first-order rate constant for the oxidation process was proportional to homogenate concentration. The role of catalase compound I in mercury vapor oxidation by brain homogenate was examined by observing the effects of two inhibitors of catalase (catalase compound I) on homogenate mercury-oxidizing activity and catalase activity. Sodium azide (50 mM) completely inhibited both mercury-oxidizing activity and catalase activity. Aminotriazole (3-amino-1H-1,2,4-triazole) (50 mM) completely inhibited only mercury-oxidizing activity; some residual catalase activity was found in the aminotriazole-treated homogenate. It was concluded that catalase compound I plays a major role in the oxidation of Hg degrees, but the possibility that catalase-independent pathways make a minor contribution cannot be excluded.

Amitrole↗
PubMed1995

Hepatic oxidative stress and related defenses during treatment of mice with acetylsalicylic acid and other peroxisome proliferators.

The peroxisome proliferators perfluorooctanoic acid (PFOA; 0.02% w/w), perfluorodecanoic acid (PFDA; 0.02%, w/w), nafenopin (0.125%, w/w), clofibrate (0.5%, w/w), and acetylsalicylic acid (ASA; 1%, w/w) were administered to male C57 BL/6 mice in their diet for two weeks. Parameters for Fe3+ ADP, NADPH or ascorbic acid-initiated lipid peroxidation in vitro were measured. Approximately a twofold increase in susceptibility to lipid peroxidation was obtained for all the peroxisome proliferators tested. Cotreatment of mice with the peroxisome proliferator ASA (1%, w/w) and a catalase inhibitor, 3-amino-1,2,4-triazole (AT; 0.4%, w/w) for 7 days resulted in little inhibition of peroxisome proliferation, an elevated level of H2O2 in vivo, and total inhibition of the increased susceptibility to lipid peroxidation in vitro. No increase in lipid peroxidation in vivo was observed. Certain antioxidant enzymes (DT-diaphorase, superoxide dismutase, glutathione transferase, glutathione peroxidase, and glutathione reductase) and components (ubiquinone and alpha-tocopherol) were also measured. The results showed that there was some induction of these antioxidant enzymes and components by ASA or aminotriazole, except for glutathione peroxidase and superoxide dismutase, which were inhibited. The possible involvement of oxidative stress in the carcinogenicity of peroxisome proliferators is discussed.

Acyl Coenzyme A↗
PubMed1986

Copper ions and hydrogen peroxide form hypochlorite from NaCl thereby mimicking myeloperoxidase.

Sea urchins have elaborated multiple defenses to assure monospermic fertilization. In this work, we have concentrated on a study of the mechanism(s) by which hydrogen peroxide (H2O2) prevents polyspermy in Arbacia punctulata. We found that it is not H2O2 but probably hypochlorous acid/hypochlorite (HOCl/OCl-) derived from H2O2 that is toxic to the supernumerary sperm. The spermicidal activity of H2O2 is potentiated by at least one order of magnitude by cupric ions (Cu2+). This increased toxicity is not due to the formation of hydroxyl radicals (.OH) because .OH scavengers did not counteract the activity of Cu2+. Moreover, substitution of Cu2+ by ferrous ions (Fe2+), which are known to cause formation of .OH from H2O2, had no effect on fertilization even at 10(2)-10(3) times higher concentrations. In contrast, 3-amino-1,2,4-triazole (AT), and HOCl/OCl- scavenger, totally reversed the toxic effects of Cu2+. Furthermore, we found that HOCl/OCl- is generated in solutions of H2O2 and Cu2+ in the presence of 0.5 M NaCl and that its accumulation is abolished by AT. Thus it is possible that the antifertility properties of copper are due to its ability to mediate formation of HOCl/OCl-. HOCl/OCl- generated by Cu2+ from H2O2 and Cl-, a low concentration of exogenously added HOCl/OCl-, or increased concentrations of H2O2 has similar inhibitory effects on the fertilization process in sea urchins. Therefore, we suggest that polyspermy is prevented by the action of a myeloperoxidase that affects the formation of HOCl/OCl- from the Cl- present in sea water through reaction with H2O2 generated by the newly fertilized egg.

Amitrole↗
PubMed1991

Tissue peroxidase in the normal and neoplastic salivary gland.

Peroxidase activity was measured by two colorimetric methods in six neoplastic tumors of the parotid salivary gland. When p-phenylenediamine was used as the hydrogen donor co-substrate, peroxidase activity was absent or reduced from 6 to 22% of normal in these tumors. Cross reactivity with normal peroxidase antibody could not be demonstrated in tumors exhibiting negative activity. Two neoplastic salivary glands had well-described, encapsulated tumors which showed reduced peroxidase activity when compared with the normal uninvolved portion. However, when guaiacol was substituted for p-phenylenediamine, normal activity was recorded. After dialysis, peroxidase activity was not enhanced. Mixing experiments showed no effect of the tumor extract on the peroxidase activity of normal saliva, nor on salivary gland supernatant. Normal salivary gland peroxidase was inhibited 90% by 10(-2) g/L amino-triazole, but neoplastic tumors were inhibited less (13 and 73%). It is suggested that peroxidase is a simple marker for the detection of neoplasia and can be of value in the differentiation of benign tumors.

Adenoma↗