scholarly journals Bioactivity and the First Transmission Electron Microscopy Immunogold Studies of ShortDe Novo-Designed Antimicrobial Peptides

2011 ◽  
Vol 55 (5) ◽  
pp. 2137-2145 ◽  
Author(s):  
Marisa Ann Azad ◽  
Heidi Esther Katrina Huttunen-Hennelly ◽  
Cynthia Ross Friedman
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mechanism Of Action ◽  
Design Principle ◽  
Multidrug Resistant ◽  
Order Structure ◽  
Helical Structures ◽  
Membrane Deformation ◽  
Microbial Drug Resistance ◽  
Transmission Electron

ABSTRACTIn light of the era of microbial drug resistance, the current study aimed to better understand the relationships between sequence, higher-order structure, and mechanism of action for five designed peptides against multidrug-resistant (MDR) pathogens. All peptides studied were 15 residues long, were polycationic, adopted alpha-helical structures within hydrophobic environments (excluding thed-amino acid-substituted peptide MA-d), and contained N-terminal glycine residues, a novel antimicrobial peptide (AMP) design principle. Increasing hydrophobicity enhanced MICs (≤500 μg/ml to ≤7.4 μg/ml) without significantly increasing hemolytic activity (18% maximum hemolysis at 3,400 μg/ml). To the best of our knowledge, this is the first study to have successfully adapted and used a transmission electron microscopy (TEM) immunogold method to investigate the mechanism of action of short (∼15 residues long) AMPs within bacteria. We propose a “floodgate” mechanism to possibly explain membrane deformation and the relative absence of membrane-associated peptides 10 h into incubation.

Transmission electron microscopy revealing the mechanism of action of photodynamic therapy on Trichomonas vaginalis

Acta Tropica ◽  
2019 ◽  
Vol 190 ◽  
pp. 112-118 ◽  
Author(s):  
Thaisa H.S. Fonseca ◽  
Jessica M.S. Gomes ◽  
Marina Alacoque ◽  
Marcos A. Vannier-Santos ◽  
Maria A. Gomes ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photodynamic Therapy ◽  
Mechanism Of Action ◽  
Trichomonas Vaginalis ◽  
Transmission Electron

Evaluation of Bacteriophage Cocktails Alone and in Combination with Daptomycin Against Daptomycin-Nonsusceptible Enterococcus faecium

2021 ◽  
Author(s):  
Taylor Morrisette ◽  
Katherine L. Lev ◽  
Gregory S. Canfield ◽  
Breck A. Duerkop ◽  
Razieh Kebriaei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Antibiotic Therapy ◽  
Enterococcus Faecium ◽  
Multidrug Resistant ◽  
Whole Genome ◽  
Transmission Electron ◽  
Phage Cocktail ◽  
Genome Analyses ◽  
Time Kill

Enterococcus faecium ( E. fcm ) is a significant multidrug-resistant pathogen. Bacteriophage cocktails are being proposed to complement antibiotic therapy. After a screen of 8 E. fcm strains against 4 phages, two phages(113, 9184) with the broadest host ranges were chosen for further experiments. Transmission electron microscopy, whole-genome sequencing, comparative genome analyses, and time-kill analyses were performed. Daptomycin(DAP) plus phage cocktail(113:myophage;9184:siphopage) showed bactericidal activity in most regimens, while DAP addition prevented phage 9184 resistance against daptomycin non-susceptible E. fcm .

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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