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Journal of Clinical Microbiology Jun 2017Tedizolid is a new oxazolidinone with improved and intracellular potency against , including multidrug-resistant strains, and some species of nontuberculous...
Tedizolid is a new oxazolidinone with improved and intracellular potency against , including multidrug-resistant strains, and some species of nontuberculous mycobacteria (NTM) compared with that of linezolid. Using the current Clinical and Laboratory Standards Institute (CLSI)-recommended method of broth microdilution, susceptibility testing of 170 isolates of rapidly growing mycobacteria showed equivalent or lower (1- to 8-fold) MIC and/or MIC values for tedizolid compared with that for linezolid. The tedizolid MIC values for 81 isolates of subsp. and 12 isolates of subsp. were 8 μg/ml and 4 μg/ml, respectively, compared with linezolid MIC values of 32 μg/ml for both. The MIC values for 20 isolates of were 2 μg/ml for tedizolid and 4 μg/ml for linezolid. Twenty-two isolates of had tedizolid and linezolid MICs of 2 μg/ml and 16 μg/ml, respectively. One hundred forty-two slowly growing NTM, including 7/7 , 7/7 , and 7/11 of other less commonly isolated species, had tedizolid MICs of ≤1 μg/ml and linezolid MICs of ≤4 μg/ml. One hundred isolates of complex and eight isolates had tedizolid MICs of 8 μg/ml and linezolid MICs 32 and 64 μg/ml, respectively. Nine isolates had MICs of 4 μg/ml and 16 μg/ml for tedizolid and linezolid, respectively. These findings demonstrate a greater potency of tedizolid than linezolid against NTM and suggest that an evaluation of tedizolid as a potential treatment agent for infections caused by selected NTM is warranted.
Topics: Anti-Bacterial Agents; Humans; Microbial Sensitivity Tests; Nontuberculous Mycobacteria; Organophosphates; Oxazoles
PubMed: 28330892
DOI: 10.1128/JCM.00274-17 -
Biochemistry Mar 2019Organophosphorus flame retardants are stable toxic compounds used in nearly all durable plastic products and are considered major emerging pollutants. The...
Organophosphorus flame retardants are stable toxic compounds used in nearly all durable plastic products and are considered major emerging pollutants. The phosphotriesterase from Sphingobium sp. TCM1 ( Sb-PTE) is one of the few enzymes known to be able to hydrolyze organophosphorus flame retardants such as triphenyl phosphate and tris(2-chloroethyl) phosphate. The effectiveness of Sb-PTE for the hydrolysis of these organophosphates appears to arise from its ability to hydrolyze unactivated alkyl and phenolic esters from the central phosphorus core. How Sb-PTE is able to catalyze the hydrolysis of the unactivated substituents is not known. To interrogate the catalytic hydrolysis mechanism of Sb-PTE, the pH dependence of the reaction and the effects of changing the solvent viscosity were determined. These experiments were complemented by measurement of the primary and secondary 18-oxygen isotope effects on substrate hydrolysis and a determination of the effects of changing the p K of the leaving group on the magnitude of the rate constants for hydrolysis. Collectively, the results indicated that a single group must be ionized for nucleophilic attack and that a separate general acid is not involved in protonation of the leaving group. The Brønsted analysis and the heavy atom kinetic isotope effects are consistent with an early associative transition state with subsequent proton transfers not being rate limiting. A novel binding mode of the substrate to the binuclear metal center and a catalytic mechanism are proposed to explain the unusual ability of Sb-PTE to hydrolyze unactivated esters from a wide range of organophosphate substrates.
Topics: Bacterial Proteins; Catalysis; Catalytic Domain; Deuterium; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Magnetic Resonance Spectroscopy; Organophosphates; Paraoxon; Phosphoric Triester Hydrolases; Solvents; Sphingomonadaceae; Viscosity
PubMed: 30730705
DOI: 10.1021/acs.biochem.9b00041 -
Neuropharmacology Sep 2020More frequent and widespread nerve agent attacks highlight the need for efficacious pre- and post-exposure organophosphate (OP) counter-measures to protect military and... (Review)
Review
More frequent and widespread nerve agent attacks highlight the need for efficacious pre- and post-exposure organophosphate (OP) counter-measures to protect military and civilian populations. Because of critical targeting of acetylcholinesterase (AChE) in the CNS by OPs, a pre-treatment candidate for preventing/reducing poisoning will be a broadly acting molecule that scavenges OPs in blood before they reach their physiological targets. Prophylactic human butyrylcholinesterase (HuBChE), the leading pretreatment candidate, has been shown to protect against multiple LD's of nerve agents in rodents, macaques, and minipigs. This review describes the development of a HuBChE bioscavenger pretreatment from early proof-of-concept studies to pre-clinical studies with the native injectable enzyme and the development of aerosolized forms of recombinant enzyme, which can be delivered by inhalation nebulizer devices, to effect protection against inhaled OP nerve agents and insecticides. Early animal studies utilized parenteral exposure. However, lungs are the portal of entry for most volatile OP vapors and represent the major means of OP intoxication. In this regard, pretreat-ment with 7.5 mg/kg of HuBChE by IM injection protected minipigs against lethal sarin vapor and prevented AChE inhibition in the blood. This is similar to the five-day protection in macaques by an aerosolized rHuBChE using a nebulizer against aerosolized paraoxon (estimated to be an 8 mg/kg estimated human dose). Importantly, lethal inhaled doses of OP may be smaller relative to the same dose delivered by injection, thus reducing the protective HuBChE dose, while a combination of HuBChE and post-exposure oxime may prolong protection.
Topics: Acetylcholinesterase; Animals; Butyrylcholinesterase; Cholinesterase Inhibitors; Humans; Inhalation Exposure; Macaca; Organophosphates; Species Specificity; Swine; Swine, Miniature
PubMed: 32442543
DOI: 10.1016/j.neuropharm.2020.108150 -
Marine Drugs Jan 2010Calyculins, highly cytotoxic polyketides, originally isolated from the marine sponge Discodermia calyx by Fusetani and co-workers, belong to the lithistid sponges group.... (Review)
Review
Calyculins, highly cytotoxic polyketides, originally isolated from the marine sponge Discodermia calyx by Fusetani and co-workers, belong to the lithistid sponges group. These molecules have become interesting targets for cell biologists and synthetic organic chemists. The serine/threonine protein phosphatases play an essential role in the cellular signalling, metabolism, and cell cycle control. Calyculins express potent protein phosphatase 1 and 2A inhibitory activity, and have therefore become valuable tools for cellular biologists studying intracellular processes and their control by reversible phosphorylation. Calyculins might also play an important role in the development of several diseases such as cancer, neurodegenerative diseases, and type 2-diabetes mellitus. The fascinating structures of calyculins have inspired various groups of synthetic organic chemists to develop total syntheses of the most abundant calyculins A and C. However, with fifteen chiral centres, a cyano-capped tetraene unit, a phosphate-bearing spiroketal, an anti, anti, anti dipropionate segment, an alpha-chiral oxazole, and a trihydroxylated gamma-amino acid, calyculins reach versatility that only few natural products can surpass, and truly challenge modern chemists' asymmetric synthesis skills.
Topics: Animals; Enzyme Inhibitors; Humans; Marine Toxins; Organophosphates; Oxazoles; Protein Phosphatase 1; Protein Phosphatase 2; Species Specificity; Stereoisomerism
PubMed: 20161975
DOI: 10.3390/md80100122 -
Environment International May 2023Drinks are an essential part of human diet, which makes them a source of human exposure to plasticizers such as organophosphate esters (OPEs). The current study provides...
Drinks are an essential part of human diet, which makes them a source of human exposure to plasticizers such as organophosphate esters (OPEs). The current study provides new information about sixteen OPE levels in 75 different samples (tap water, packed water, cola drinks, juice, wine and hot drinks). Tap water mean levels (40.9 ng/L) were statistically higher than packed water mean levels (4.82 ng/L), mainly due to the contribution of tris(2-chloroisopropyl) phosphate (TCIPP) and tris(2-butoxyethyl) phosphate (TBOEP) that may come from PVC water pipes. Over 90% of samples presented at least one OPE, where regular cola drinks had the highest mean concentrations (2876 ng/L). There was a significantly higher presence of OPEs in added sugar beverages than sugar free drinks, especially for 2-ethylhexyl diphenyl phosphate (EHDPP), which might be related not only to packaging materials but to the added sugar content. Estimated daily intakes (EDIs) in normal and high-exposure scenarios were 2.52 ng/kg bw/day and 7.43 ng/kg bw/day, respectively. Human risk associated with beverages ingestion showed regular cola drinks, juice and tap water as the groups with the highest hazard quotients (HQs). Although OPE exposure was below to safety limits, it should be noted that EHDPP values for regular cola group must be cause of concern, and other routes of exposure such as food ingestion or air inhalation should be also considered.
Topics: Humans; Flame Retardants; Esters; Organophosphates; Phosphates; Beverages; Environmental Monitoring; China
PubMed: 37088006
DOI: 10.1016/j.envint.2023.107936 -
International Journal of Molecular... Apr 2022Tris (2-ethylhexyl) phosphate (TEHP) is an organophosphate flame retardant (OPFRs) which is extensively used as a plasticizer and has been detected in human body fluids....
Tris (2-ethylhexyl) phosphate (TEHP) is an organophosphate flame retardant (OPFRs) which is extensively used as a plasticizer and has been detected in human body fluids. Contemporarily, toxicological studies on TEHP in human cells are very limited and there are few studies on its genotoxicity and cell death mechanism in human liver cells (HepG2). Herein, we find that HepG2 cells exposed to TEHP (100, 200, 400 µM) for 72 h reduced cell survival to 19.68%, 49.83%, 58.91% and 29.08%, 47.7% and 57.90%, measured by MTT and NRU assays. TEHP did not induce cytotoxicity at lower concentrations (5, 10, 25, 50 µM) after 24 h and 48 h of exposure. Flow cytometric analysis of TEHP-treated cells elevated intracellular reactive oxygen species (ROS), nitric oxide (NO), Ca influx and esterase levels, leading to mitochondrial dysfunction (Δ). DNA damage analysis by comet assay showed 4.67, 9.35, 13.78-fold greater OTM values in TEHP (100, 200, 400 µM)-treated cells. Cell cycle analysis exhibited 23.1%, 29.6%, and 50.8% of cells in SubG1 apoptotic phase after TEHP (100, 200 and 400 μM) treatment. Immunofluorescence data affirmed the activation of P53, caspase 3 and 9 proteins in TEHP-treated cells. In qPCR array of 84 genes, HepG2 cells treated with TEHP (100 µM, 72 h) upregulated 10 genes and downregulated 4 genes belonging to a human cancer pathway. Our novel data categorically indicate that TEHP is an oxidative stressor and carcinogenic entity, which exaggerates mitochondrial functions to induce cyto- and genotoxicity and cell death, implying its hepatotoxic features.
Topics: DNA Damage; Humans; Liver; Organophosphates; Organophosphorus Compounds; Phosphates; Transcriptome
PubMed: 35409358
DOI: 10.3390/ijms23073998 -
Applied and Environmental Microbiology Oct 2016Organophosphate pesticides used in agriculture can pose health risks to humans and wildlife. We hypothesized that dietary supplementation with Lactobacillus, a genus of...
UNLABELLED
Organophosphate pesticides used in agriculture can pose health risks to humans and wildlife. We hypothesized that dietary supplementation with Lactobacillus, a genus of commensal bacteria, would reduce absorption and toxicity of consumed organophosphate pesticides (parathion and chlorpyrifos [CP]). Several Lactobacillus species were screened for toleration of 100 ppm of CP or parathion in MRS broth based on 24-h growth curves. Certain Lactobacillus strains were unable to reach stationary-phase culture maxima and displayed an abnormal culture morphology in response to pesticide. Further characterization of commonly used, pesticide-tolerant and pesticide-susceptible, probiotic Lactobacillus rhamnosus strain GG (LGG) and L. rhamnosus strain GR-1 (LGR-1), respectively, revealed that both strains could significantly sequester organophosphate pesticides from solution after 24-h coincubations. This effect was independent of metabolic activity, as L. rhamnosus GG did not hydrolyze CP and no difference in organophosphate sequestration was observed between live and heat-killed strains. Furthermore, LGR-1 and LGG reduced the absorption of 100 μM parathion or CP in a Caco-2 Transwell model of the small intestine epithelium. To determine the effect of sequestration on acute toxicity, newly eclosed Drosophila melanogaster flies were exposed to food containing 10 μM CP with or without supplementation with live LGG. Supplementation with LGG simultaneously, but not with administration of CP 3 days prior (prophylactically), mitigated CP-induced mortality. In summary, the results suggest that L. rhamnosus may be useful for reducing toxic organophosphate pesticide exposure via passive binding. These findings could be transferable to clinical and livestock applications due to affordability and practical ability to supplement products with food-grade bacteria.
IMPORTANCE
The consequences of environmental pesticide pollution due to widespread usage in agriculture and soil leaching are becoming a major societal concern. Although the long-term effects of low-dose pesticide exposure for humans and wildlife remain largely unknown, logic suggests that these chemicals are not aligned with ecosystem health. This observation is most strongly supported by the agricultural losses associated with honeybee population declines, known as colony collapse disorder, in which pesticide usage is a likely trigger. Lactobacilli are bacteria used as beneficial microorganisms in fermented foods and have shown potentials to sequester and degrade environmental toxins. This study demonstrated that commonly used probiotic strains of lactobacilli could sequester, but not metabolize, organophosphate pesticides (parathion and chlorpyrifos). This Lactobacillus-mediated sequestration was associated with decreased intestinal absorption and insect toxicity in appropriate models. These findings hold promise for supplementing human, livestock, or apiary foods with probiotic microorganisms to reduce organophosphate pesticide exposure.
Topics: Animals; Caco-2 Cells; Chlorpyrifos; Drosophila melanogaster; Female; Humans; Lacticaseibacillus rhamnosus; Male; Organophosphates; Pesticides; Probiotics
PubMed: 27520820
DOI: 10.1128/AEM.01510-16 -
The Science of the Total Environment Dec 2018Organophosphates (OP) are widely used insecticides that acutely inhibit acetylcholinesterase enzyme activity. There is great interest in improving the understanding of...
BACKGROUND
Organophosphates (OP) are widely used insecticides that acutely inhibit acetylcholinesterase enzyme activity. There is great interest in improving the understanding of molecular mechanisms related to chronic OP exposure induced toxicity. We aim to elucidate epigenetic changes associated with OP exposure, using untargeted analysis of genome-wide DNA methylation data.
METHODS
In a population-based case control study of Parkinson's disease (PD), we assessed ambient OP exposure via residential and workplace proximity to commercial applications. We investigated associations between OP exposure and genome-wide DNA methylation (Illumina 450 k) in 580 blood samples (342 PD patients, 238 controls) and 259 saliva samples (128 patients, 131 controls). To identify differential methylation related to OP exposure, we controlled for age, sex, European ancestry, and PD status; in addition, we stratified by disease status.
RESULTS
We identified 70 genome-wide significant CpGs, including cg01600516 in ALOX12 (cor = 0.27, p = 1.73E-11) and two CpGs in HLA genes, cg01655658 (cor = -0.24, p = 2.80E-09) in HLA-L (pseudogene) and cg15680603 (cor = 0.20, p = 7.94E-07) in HLA-DPA1. Among the 70 CpGs located in 41 genes, 14 were also differentially methylated in saliva samples. The most overrepresented pathway was the nicotinic acetylcholine receptor signaling pathway (fold enrichment = 15.63, p = 1.01E-03, FDR = 1.64E-01). Expanding to a larger number of genes (CpG p < 5E-04, FDR < 2.25E-01; 1077 CpGs, 662 genes), the most enriched pathway shifted to the muscarinic acetylcholine receptor 1 and 3 signaling pathway (p-value = 5.36E-04, FDR = 4.73E-02). When we stratified by PD status, results were similar. Of the 70 significant CpGs, 63 were detected among both patients and controls and 7 were only associated with OP exposure among patients.
CONCLUSIONS
This study finds chronic low-level OP exposure is associated with differential DNA methylation in blood and saliva, both in elderly population controls and PD patients. Our study results suggest that long-term sub-acute OP exposure influences methylation in genes enriched for muscarinic and nicotinic acetylcholine receptor pathways.
Topics: Aged; Case-Control Studies; DNA Methylation; Environmental Exposure; Epigenesis, Genetic; Humans; Organophosphates; Pesticides
PubMed: 30248838
DOI: 10.1016/j.scitotenv.2018.07.143 -
Environment International May 2021Per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs) are found in building materials and associated with...
Per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs) are found in building materials and associated with thyroid disease, infertility, and impaired development. This study's objectives were to (1) compare levels of PFAS, PBDEs, and OPEs in dust from spaces with conventional versus "healthier" furniture and carpet, and (2) identify other product sources of flame retardants in situ. We measured 15 PFAS, 8 PBDEs, and 19 OPEs in dust from offices, common areas, and classrooms having undergone either no intervention (conventional rooms in older buildings meeting strict fire codes; n = 12), full "healthier" materials interventions (rooms with "healthier" materials in buildings constructed more recently or gut-renovated; n = 7), or partial interventions (other rooms with at least "healthier" foam furniture but more potential building contamination; n = 28). We also scanned all materials for bromine and phosphorus as surrogates of PBDEs and OPEs respectively, using x-ray fluorescence. In multilevel regression models, rooms with full "healthier" materials interventions had 78% lower dust levels of PFAS than rooms with no intervention (p < 0.01). Rooms with full "healthier" interventions also had 65% lower OPE levels in dust than rooms with no intervention (p < 0.01) and 45% lower PBDEs than rooms with only partial interventions (p < 0.10), adjusted for covariates related to insulation, electronics, and furniture. Bromine loadings from electronics in rooms were associated with PBDE concentrations in dust (p < 0.05), and the presence of exposed insulation was associated with OPE dust concentrations (p < 0.001). Full "healthier" materials renovations successfully reduced chemical classes in dust. Future interventions should address electronics, insulation, and building cross-contamination.
Topics: Air Pollution, Indoor; Dust; Environmental Monitoring; Esters; Flame Retardants; Halogenated Diphenyl Ethers; Organophosphates
PubMed: 33092866
DOI: 10.1016/j.envint.2020.106151 -
Bioorganic & Medicinal Chemistry Letters Aug 2019The class A β-lactamase BlaC is a cell surface expressed serine hydrolase of Mycobacterium tuberculosis (Mtb), one of the causative agents for Tuberculosis in humans....
The class A β-lactamase BlaC is a cell surface expressed serine hydrolase of Mycobacterium tuberculosis (Mtb), one of the causative agents for Tuberculosis in humans. Mtb has demonstrated increased susceptibility to β-lactam antibiotics upon inactivation of BlaC; thus, making BlaC a rational enzyme target for therapeutic agents. Herein, we present the synthesis and structure-activity-relationship data for the 1st-generation library of bis(benzoyl) phosphates (1-10). Substituent effects ranged from σ = -0.27 to 0.78 for electronic and π = -0.41 to 1.98 for hydrophobic parameters. Compounds 1, 4 and 5 demonstrated the greatest inhibitory potency against BlaC in a time-dependent manner (k = 0.212, 0.324, and 0.450 mn respectively). Combined crystal structure data and mass spectrometric analysis of a tryptic digest for BlaC inactivated with 4 provided evidence that the mechanism of inactivation by this bis(benzoyl) phosphate scaffold occurs via phosphorylation of the active-site Ser-70, ultimately leading to an aged form of the enzyme.
Topics: Catalytic Domain; Crystallography, X-Ray; Enzyme Assays; Molecular Structure; Mycobacterium tuberculosis; Organophosphates; Phosphorylation; Serine; Small Molecule Libraries; Structure-Activity Relationship; beta-Lactamase Inhibitors; beta-Lactamases
PubMed: 31281019
DOI: 10.1016/j.bmcl.2019.07.002