A swinging seesaw as a novel model mechanism for time-dependent hormesis under dose-dependent stimulatory and inhibitory effects: A case study on the toxicity of antibacterial chemicals to Aliivibrio fischeri

Chemosphere ◽  
2018 ◽  
Vol 205 ◽  
pp. 15-23 ◽  
Author(s):  
Haoyu Sun ◽  
Edward J. Calabrese ◽  
Min Zheng ◽  
Dali Wang ◽  
Yongzheng Pan ◽  
...  
Keyword(s):  
Time Dependent ◽  
Inhibitory Effects ◽  
Aliivibrio Fischeri ◽  
Dose Dependent ◽  
Novel Model

Regular time-dependent cross-phenomena induced by hormesis: A case study of binary antibacterial mixtures to Aliivibrio fischeri

2020 ◽  
Vol 187 ◽  
pp. 109823 ◽  
Author(s):  
Haoyu Sun ◽  
Yongzheng Pan ◽  
Xiang Chen ◽  
Wei Jiang ◽  
Zhifen Lin ◽  
...  
Keyword(s):  
Time Dependent ◽  
Regular Time ◽  
Aliivibrio Fischeri

Mechanism for depression of heart sarcolemmal Ca2+ pump by oxygen free radicals

1989 ◽  
Vol 257 (3) ◽  
pp. H804-H811 ◽  
Author(s):  
M. Kaneko ◽  
V. Elimban ◽  
N. S. Dhalla
Keyword(s):  
Free Radicals ◽  
Oxygen Free Radicals ◽  
Sulfhydryl Group ◽  
Sulfhydryl Groups ◽  
Time Dependent ◽  
Dependent Manner ◽  
Protective Effects ◽  
Inhibitory Effects ◽  
Sulfhydryl Reagents ◽  
Dose Dependent

To understand the involvement of changes in sulfhydryl groups in causing depression of the sarcolemmal Ca2+-pump activities, this study was undertaken to examine the effects of oxygen free radicals on rat heart sarcolemmal sulfhydryl groups, Ca2+-stimulated adenosinetriphosphatase (ATPase), and ATP-dependent Ca2+ accumulation. In addition, the effects of sulfhydryl reagents such as dithiothreitol, cysteine, and N-ethylmaleimide on Ca2+-pump activities were investigated. The inhibition of sarcolemmal Ca2+-pump activities by O2-. (xanthine + xanthine oxidase) and H2O2 was decreased by the addition of dithiothreitol or cysteine in a dose-dependent manner. N-ethylmaleimide also showed inhibitory effects on Ca2+-pump activities both in a dose- and time-dependent manner; dithiothreitol and cysteine prevented changes in Ca2+-pump activities because of N-ethylmaleimide. Heart sarcolemmal sulfhydryl groups were depressed by O2-., H2O2, and .OH (H2O2 + Fe2+) both in a dose- and time-dependent manner. Superoxide dismutase, catalase, and D-mannitol showed protective effects on the sulfhydryl group depression by O2-., H2O2, and .OH, respectively. A significant correlation between changes in sarcolemmal Ca2+-stimulated ATPase activity and sarcolemmal sulfhydryl groups was seen. These results indicate that oxygen free radicals may depress the heart sarcolemmal Ca2+-pump activities by modifying the sulfhydryl groups in the sarcolemmal membrane.

Interaction between amrinone and parathyroid hormone on bone in culture

1982 ◽  
Vol 243 (6) ◽  
pp. E499-E504
Author(s):  
N. S. Krieger ◽  
P. H. Stern
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Direct Interaction ◽  
Inhibitory Effects ◽  
Dihydroxyvitamin D3 ◽  
Basal Bone ◽  
Cardiotonic Agent ◽  
Neonatal Mouse Calvaria ◽  
Dose Dependent ◽  
Stimulation Of

The cardiotonic agent amrinone has been postulated to directly affect Na-Ca exchange. Because stimulated bone resorption has been proposed to require Na-Ca exchange, we examined the effects of amrinone on bone. Amrinone inhibited release of Ca from neonatal mouse calvaria in organ culture stimulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin d3, or prostaglandin E2. Inhibition was dose dependent and maximal at 2 X 10(-4) M. The effect of amrinone differed from the inhibitory effects of calcitonin, ouabain, or nigericin in that 1) 6-h exposure to amrinone alone prevented the effect of subsequently added PTH; 2) amrinone was only partially effective if added after resorption was initiated by 24-h treatment with PTH; 3) coincubation with amrinone and PTH during the first 48 h of culture allowed for a response to PTH after amrinone was removed; no such protection by a stimulator occurred with ouabain or nigericin. Also submaximal concentrations of amrinone plus calcitonin, ouabain, or nigericin gave greater than additive inhibition of Ca release. Amrinone had no effect on basal bone cAMP or on the acute stimulation of cAMP by PTH. The results suggest that amrinone could have a more direct interaction with the pathway involved in stimulated bone resorption than the other inhibitors.

scholarly journals Assessment of Cyto/Genotoxicity of Irinotecan in V79 Cells Using the Comet, Micronucleus, and Chromosome Aberration Assay

2010 ◽  
Vol 61 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Vilena Kašuba ◽  
Ružica Rozgaj ◽  
Marija Gamulin ◽  
Ivančica Trošić
Keyword(s):  
Comet Assay ◽  
Chromosome Aberration ◽  
Topoisomerase I ◽  
Micronucleus Test ◽  
Statistical Significance ◽  
Time Dependent ◽  
V79 Cells ◽  
Chromosome Aberration Assay ◽  
Dependent Relation ◽  
Dose Dependent

Assessment of Cyto/Genotoxicity of Irinotecan in V79 Cells Using the Comet, Micronucleus, and Chromosome Aberration AssayIrinotecan is a topoisomerase I interactive agent, widely used in the treatment of metastatic colorectal cancer. The genotoxic effects of the maximum single dose (18 μg mL-1), recommended monotherapy dose (9 μg mL-1), and recommended combined therapy dose (4.5 μg mL-1) of irinotecan were studied on V79 cells using the comet assay, chromosome aberration assay, and micronucleus test. The cells were treated with irinotecan for 2 h or 24 h. The statistical significance of the results was determined using the one-way ANOVA test and a nonparametric Mann Whitney U test. The comet assay did not show dose-dependent or time-dependent effects. The chromosome aberration analysis showed large DNA rearrangements, i.e., chromosome exchanges. Although the exposed cultures showed a significant increase in micronucleated cells in respect to control, no dose-dependent relation was established among the treated cultures. Time-dependent effect was also not observed.

cAMP inhibition of interleukin-1-induced interleukin-6 production by human lung fibroblasts

1993 ◽  
Vol 264 (3) ◽  
pp. L253-L260 ◽  
Author(s):  
R. J. Zitnik ◽  
T. Zheng ◽  
J. A. Elias
Keyword(s):  
Human Lung ◽  
Interleukin 1 ◽  
Cell Number ◽  
Lung Fibroblasts ◽  
Intracellular Camp ◽  
Inhibitory Effects ◽  
Mrna Accumulation ◽  
Human Lung Fibroblasts ◽  
Dose Dependent ◽  
Necrosis Factor

We characterized the effects of agents that alter intracellular adenosine 3',5'-cyclic monophosphate (cAMP) on the interleukin (IL)-6 production of human lung fibroblasts. Unstimulated fibroblasts did not produce significant amounts of IL-6. Recombinant (r) tumor necrosis factor (TNF) weakly stimulated, recombinant interleukin-1-alpha (rIL-1 alpha) strongly stimulated, and rIL-1 alpha and rTNF in combination synergistically augmented fibroblast IL-6 production. Prostaglandin (PG)E1, forskolin, dibutyryl cAMP (DBcAMP), 3-isobutyl-1-methylxanthine (IBMX), and cholera toxin did not cause a detectable alteration in the IL-6 production of unstimulated fibroblasts. However, these agents inhibited the IL-6 production of rIL-1 and rIL-1 plus rTNF-stimulated cells. These effects were dose dependent with a concentration of 2 x 10(-9) M PGE1, 5 x 10(-6) M forskolin, 5 x 10(-4) M DBcAMP, and 1 x 10(-3) M IBMX decreasing rIL-1 alpha (2.5 ng/ml)-induced IL-6 production by approximately 50%. The inhibitory effects of these agents, correlated with their ability to induce fibroblast cAMP accumulation, could not be explained by alterations in cell number or viability and were appreciable even when cAMP modifiers were added to fibroblast culture, 1 h after rIL-1. They were also at least partly specific for rIL-1, since these agents increased the IL-6 production of rTNF-stimulated cells. These cAMP-induced alterations in IL-6 production were associated with corresponding alterations in IL-6 mRNA accumulation. Nuclear run-on analysis demonstrated that the inhibitory effects of PGE1 were associated with a comparable decrease in IL-6 transcription. Agents that increase the levels of intracellular cAMP inhibit rIL-1-induced IL-6 by human lung fibroblasts.

Isolation of the antidiarrhoeal tiliroside and its derivative from Waltheria indica leaf extract

2021 ◽  
Vol 25 (1) ◽  
pp. 86-92
Author(s):  
B.A. Ayinde ◽  
J.O. Owolabi ◽  
I.S. Uti ◽  
P.C. Ogbeta ◽  
M.I. Choudhary
Keyword(s):  
Silica Gel ◽  
Column Chromatography ◽  
Methanol Extract ◽  
Preparative Thin Layer Chromatography ◽  
Inhibitory Effects ◽  
Aqueous Fraction ◽  
Vacuum Liquid Chromatography ◽  
Ileum Contraction ◽  
Layer Chromatography ◽  
Dose Dependent

The antidiarrhoeal effect of Waltheria indica methanol extract and fractions have been reported earlier but, the present work examined the intestinal relaxant effects of two flavonoid-phenyl propanoids isolated from the methanol extract. The active aqueous fraction was subjected to vacuum liquid chromatography using dichloromethane with increasing concentration of ethyl acetate, and that of methanol and water successively. The ten (10) fractions obtained were combined to give seven (7). The fraction 2 (C, D) was subjected to preparative thin layer chromatography on silica gel GF254 (10-40μm) using CHCl3-CH3OH (8:2) to obtain compound coded F2. Fraction 4 (F) was subjected to column chromatography using silica gel (60-120μm mesh) and eluted with  dichloromethane with increasing concentrations of methanol. Fractions 9-28 were combined and subjected to column  chromatography using chloroform with increasing concentration of methanol. The fractions 1-16 of these were purified on Sephadex LH-20 to obtain compound BAA. The identities of the two compounds were established using spectroscopic methods. The  antidiarrheal effect of compound F2 was evaluated on mice using charcoal transit (100,200, 400mg/kg), castor oil (40, 60 mg/kg)  while the two compounds were examined for their inhibitory effects on Ach-induced ileum contraction. The effects of the  compounds were compared with loperamide (3mg/kg) and atropine (80μg). Compounds F2 and BAA were identified as tiliroside and 3’’’, 5’’’-dimethoxy tiliroside respectively. Tiliroside inhibited the charcoal transition in the animals in a dose dependent pattern with 400mg/ mL eliciting 63.41% inhibition compared to 59.23% produced by loperamide. The compound also elicited significantly (P<0.05) prolonged onset of stooling and reduced the number and weight of stools produced lower than the control. The two  compounds drastically inhibited the Ach-induced contractions of the ileum. The compound, tiliroside at 10mg, completely abolished  the contraction by Ach unlike 3’’’, 5’’’-dimethoxy tiliroside which reduced the contraction to 1.92% at 20mg. The identified compounds seem to be responsible for the ethnomedicinal use of the plant in treating diarrhea.

Assessing Bypassed Hydrocarbons

2021 ◽  
Author(s):  
Stanley Oifoghe ◽  
Nora Alarcon ◽  
Lucrecia Grigoletto
Keyword(s):  
Continental Shelf ◽  
Reservoir Characterization ◽  
Gamma Ray ◽  
West African ◽  
The Novel ◽  
The West ◽  
Present Case Study ◽  
Novel Model

Abstract Hydrocarbons are bypassed in known fields. This is due to reservoir heterogeneities, complex lithology, and limitations of existing technology. This paper seeks to identify the scenarios of bypassed hydrocarbons, and to highlight how advances in reservoir characterization techniques have improved assessment of bypassed hydrocarbons. The present case study is an evaluation well drilled on the continental shelf, off the West African Coastline. The targeted thin-bedded reservoir sands are of Cenomanian age. Some technologies for assessing bypassed hydrocarbon include Gamma Ray Spectralog and Thin Bed Analysis. NMR is important for accurate reservoir characterization of thinly bedded reservoirs. The measured NMR porosity was 15pu, which is 42% of the actual porosity. Using the measured values gave a permeability of 5.3mD as against the actual permeability of 234mD. The novel model presented in this paper increased the porosity by 58% and the permeability by 4315%.

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