Hydroquinone Diphosphate as a Phosphatase Substrate in Enzymatic Amplification Combined with Electrochemical–Chemical–Chemical Redox Cycling for the Detection of E. coli O157:H7

2013 ◽  
Vol 85 (3) ◽  
pp. 1631-1636 ◽  
Author(s):  
Md. Rajibul Akanda ◽  
Vellaiappillai Tamilavan ◽  
Seonhwa Park ◽  
Kyungmin Jo ◽  
Myung Ho Hyun ◽  
...  
Keyword(s):  
Redox Cycling ◽  
E Coli ◽  
Enzymatic Amplification ◽  
Phosphatase Substrate

DT-Diaphorase as a Bifunctional Enzyme Label That Allows Rapid Enzymatic Amplification and Electrochemical Redox Cycling

2017 ◽  
Vol 89 (15) ◽  
pp. 7974-7980 ◽  
Author(s):  
Cheolho Kang ◽  
Juyeon Kang ◽  
Nam-Sihk Lee ◽  
Young Ho Yoon ◽  
Haesik Yang
Keyword(s):  
Redox Cycling ◽  
Bifunctional Enzyme ◽  
Enzymatic Amplification ◽  
Enzyme Label ◽  
Electrochemical Redox ◽  
Dt Diaphorase

Antimicrobial and antifungal activities of bifunctional cooper(ii) complexes with non-steroidal anti-inflammatory drugs, flufenamic, mefenamic and tolfenamic acids and 1,10-phenanthroline

2020 ◽  
Vol 18 (1) ◽  
pp. 1444-1451
Author(s):  
Lenka Hudecova ◽  
Klaudia Jomova ◽  
Peter Lauro ◽  
Miriama Simunkova ◽  
Saleh H. Alwasel ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Antibacterial Activities ◽  
Redox Cycling ◽  
Yeast Cells ◽  
Model Organisms ◽  
Flufenamic Acid ◽  
Antifungal Activities ◽  
E Coli ◽  
Inflammatory Drugs ◽  
Anti Inflammatory

AbstractCooper(ii) complexes represent a promising group of compounds with antimicrobial and antifungal properties. In the present work, a series of Cu(ii) complexes containing the non-steroidal anti-inflammatory drugs, tolfenamic acid, mefenamic acid and flufenamic acid as their redox-cycling functionalities, and 1,10-phenanthroline as an intercalating component, has been studied. The antibacterial activities of all three complexes, [Cu(tolf-O,O′)2(phen)] (1), [Cu(mef-O,O′)2(phen)] (2) and [Cu(fluf-O,O′)2(phen)] (3), were tested against the prokaryotic model organisms Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and their antifungal activities were evaluated towards the yeast, Saccharomyces cerevisiae (S. cerevisiae). The antibacterial activity of both strains has been compared with the antibiotic Neomycin. The calculated IC50 values revealed slight differences in the antibacterial activities of the complexes in the order 1 ∼ 3 > 2. The most profound growth inhibition of E. coli was observed, at its highest concentration, for the complex 1, which contains chlorine atoms in the ligand environment. The trend obtained from IC50 values is generally in agreement with the determined MIC values. Similarly, the complex 1 showed the greatest growth inhibition of the yeast S. cerevisiae and the overall antifungal activities of the Cu(ii) complexes were found to follow the order 1 > 3 ≫ 2. However, for complex 2, even at the highest concentration tested (150 μM), a 50% decrease in yeast growth was not achieved. It appears that the most potent antimicrobial and antifungal Cu(ii) complexes are those containing halogenated NSAIDs. The mechanisms by which Cu(ii) complexes cause antibacterial and antifungal activities can be understood on the basis of redox-cycling reactions between cupric and cuprous species which lead to the formation of free radicals. The higher efficacy of the Cu(ii) complexes against bacterial cells may be due to an absence of membrane-protected nuclear DNA, meaning that on entering a cell, they can interact directly with its DNA. Contrastingly, for the complexes to interact with the DNA in yeast cells, they must first penetrate through the nuclear membrane.

scholarly journals Redox cycling amplified electrochemical detection of DNA hybridization: Application to pathogen E. coli bacterial RNA

2011 ◽  
Vol 689 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Anne Walter ◽  
Jie Wu ◽  
Gerd-Uwe Flechsig ◽  
David A. Haake ◽  
Joseph Wang
Keyword(s):  
Electrochemical Detection ◽  
Dna Hybridization ◽  
Redox Cycling ◽  
E Coli ◽  
Bacterial Rna

scholarly journals Balance between Endogenous Superoxide Stress and Antioxidant Defenses

1998 ◽  
Vol 180 (6) ◽  
pp. 1402-1410 ◽  
Author(s):  
Amy Strohmeier Gort ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Dna Damage ◽  
Superoxide Dismutase ◽  
Excellent Agreement ◽  
Redox Cycling ◽  
Enzyme Inactivation ◽  
Antioxidant Defenses ◽  
Wild Type ◽  
E Coli ◽  
Soxrs Regulon

ABSTRACT Cells devoid of cytosolic superoxide dismutase (SOD) suffer enzyme inactivation, growth deficiencies, and DNA damage. It has been proposed that the scant superoxide (O2 −) generated by aerobic metabolism harms even cells that contain abundant SOD. However, this idea has been difficult to test. To determine the amount of O2 − that is needed to cause these defects, we modulated the O2 − concentration insideEscherichia coli by controlling the expression of SOD. An increase in O2 − of more than twofold above wild-type levels substantially diminished the activity of labile dehydratases, an increase in O2 − of any more than fourfold measurably impaired growth, and a fivefold increase in O2 − sensitized cells to DNA damage. These results indicate that E. coli constitutively synthesizes just enough SOD to defend biomolecules against endogenous O2 − so that modest increases in O2 − concentration diminish cell fitness. This conclusion is in excellent agreement with quantitative predictions based upon previously determined rates of intracellular O2 − production, O2 −dismutation, dehydratase inactivation, and enzyme repair. The vulnerability of bacteria to increased intracellular O2 − explains the widespread use of superoxide-producing drugs as bactericidal weapons in nature. E. coli responds to such drugs by inducing the SoxRS regulon, which positively regulates synthesis of SOD and other defensive proteins. However, even toxic amounts of endogenous O2 −did not activate SoxR, and SoxR activation by paraquat was not at all inhibited by excess SOD. Therefore, in responding to redox-cycling drugs, SoxR senses some signal other than O2 −.

Endotoxin Alteration of the Mucopolysaccharide Blood Vessel Coating in Rats

1974 ◽  
Vol 32 ◽  
pp. 148-149
Author(s):  
D. E. Philpott ◽  
A. Takahashi
Keyword(s):  
Skeletal Muscle ◽  
Endothelial Cells ◽  
Salivary Gland ◽  
Carotid Artery ◽  
Basement Membrane ◽  
Coronary Vessels ◽  
Ruthenium Red ◽  
E Coli ◽  
Old Rats ◽  
The Brain

Two month, eight month and two year old rats were treated with 10 or 20 mg/kg of E. Coli endotoxin I. P. The eight month old rats proved most resistant to the endotoxin. During fixation the aorta, carotid artery, basil arartery of the brain, coronary vessels of the heart, inner surfaces of the heart chambers, heart and skeletal muscle, lung, liver, kidney, spleen, brain, retina, trachae, intestine, salivary gland, adrenal gland and gingiva were treated with ruthenium red or alcian blue to preserve the mucopolysaccharide (MPS) coating. Five, 8 and 24 hrs of endotoxin treatment produced increasingly marked capillary damage, disappearance of the MPS coating, edema, destruction of endothelial cells and damage to the basement membrane in the liver, kidney and lung.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Emigration of neutrophils in the central nervous system

1983 ◽  
Vol 41 ◽  
pp. 788-789
Author(s):  
John L.Beggs ◽  
John D. Waggener ◽  
Wanda Miller ◽  
Jane Watkins
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Osmium Tetroxide ◽  
White Blood Cells ◽  
Arterial Perfusion ◽  
E Coli ◽  
Intracisternal Injection ◽  
The Central Nervous System ◽  
Brain And Spinal Cord ◽  
Interendothelial Junctions

Studies using mesenteric and ear chamber preparations have shown that interendothelial junctions provide the route for neutrophil emigration during inflammation. The term emigration refers to the passage of white blood cells across the endothelium from the vascular lumen. Although the precise pathway of transendo- thelial emigration in the central nervous system (CNS) has not been resolved, the presence of different physiological and morphological (tight junctions) properties of CNS endothelium may dictate alternate emigration pathways.To study neutrophil emigration in the CNS, we induced meningitis in guinea pigs by intracisternal injection of E. coli bacteria.In this model, leptomeningeal inflammation is well developed by 3 hr. After 3 1/2 hr, animals were sacrificed by arterial perfusion with 3% phosphate buffered glutaraldehyde. Tissues from brain and spinal cord were post-fixed in 1% osmium tetroxide, dehydrated in alcohols and propylene oxide, and embedded in Epon. Thin serial sections were cut with diamond knives and examined in a Philips 300 electron microscope.

Use of Uranium-Labeled Antibodies for Electron Microscopic Localization of Various Antigens in Mammalian Cells

1967 ◽  
Vol 25 ◽  
pp. 136-137
Author(s):  
J. P. Petrali ◽  
E. J. Donati ◽  
L. A. Sternberger
Keyword(s):  
Endoplasmic Reticulum ◽  
Hela Cells ◽  
Mammalian Cells ◽  
Specific Antiserum ◽  
Electron Microscopic ◽  
E Coli ◽  
Cytoplasmic Membranes ◽  
Viral Progeny ◽  
Ultrathin Sections ◽  
Electron Microscopic Localization

Specific contrast is conferred to subcellular antigen by applying purified antibodies, exhaustively labeled with uranium under immunospecific protection, to ultrathin sections. Use of Seligman’s principle of bridging osmium to metal via thiocarbohydrazide (TCH) intensifies specific contrast. Ultrathin sections of osmium-fixed materials were stained on the grid by application of 1) thiosemicarbazide (TSC), 2) unlabeled specific antiserum, 3) uranium-labeled anti-antibody and 4) TCH followed by reosmication. Antigens to be localized consisted of vaccinia antigen in infected HeLa cells, lysozyme in monocytes of patients with monocytic or monomyelocytic leukemia, and fibrinogen in the platelets of these leukemic patients. Control sections were stained with non-specific antiserum (E. coli).In the vaccinia-HeLa system, antigen was localized from 1 to 3 hours following infection, and was confined to degrading virus, the inner walls of numerous organelles, and other structures in cytoplasmic foci. Surrounding architecture and cellular mitochondria were unstained. 8 to 14 hours after infection, antigen was localized on the outer walls of the viral progeny, on cytoplasmic membranes, and free in the cytoplasm. Staining of endoplasmic reticulum was intense and focal early, and weak and diffuse late in infection.

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