Scanning electron microscopy of morphological alterations in Proteus mirabilis induced by cephalosporins and semisynthetic penicillins

1973 ◽  
Vol 19 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Robert L. Perkins ◽  
Marcia A. Miller
Keyword(s):  
Electron Microscopy ◽  
Proteus Mirabilis ◽  
Mechanisms Of Action ◽  
Structural Alterations ◽  
Beam Electron ◽  
Morphological Alterations ◽  
Low Concentrations ◽  
High Concentrations ◽  
Marked Cell ◽  
Scanning Electron

Experiments, using the scanning-beam electron microscope, were conducted to compare the morphologic lesions induced in a strain of Proteus mirabilis by two semisynthetic penicillins, ampicillin and carbenicillin, and two cephalosporins, cephalothin and cephaloridine. The observations demonstrated that the semisynthetic penicillins and cephalosporins did not induce the same sequence of structural alterations. In the presence of cephalothin or cephaloridine, mid-cell spherical defects were induced which rapidly progressed to large bulbous enlargements at low concentrations (2 and 20 μg/ml) but only spheroplast-like forms were observed at high concentrations (200 and 2000 μg/ml). Ampicillin and carbenicillin caused similar alterations in morphology except that marked cell elongation without division occurred with 2 and 20 μg/ml. These variations may reflect subtle differences in sites, rates, sensitivity, or mechanisms of action between these two groups of cell-wall inhibiting antibiotics.

scholarly journals Differential Effect of Isooctane Doses on HaCaT and HeLa: A Multimodal Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Lopamudra Das ◽  
Sanmitra Basu ◽  
Sanghamitra Sengupta ◽  
Soumen Das ◽  
Jyotirmoy Chatterjee
Keyword(s):  
Electron Microscopy ◽  
Multimodal Approach ◽  
Cytotoxic Effects ◽  
Structural Alterations ◽  
Morphological Alterations ◽  
Multimodal Analysis ◽  
Viability Assay ◽  
Immunocytochemical Studies ◽  
Different Doses ◽  
Scanning Electron

A multimodal approach is effective in analyzing biological problems critically and thus also useful in assessing cytotoxicity under chemicals assaults. In this study effects of isooctane, an organic solvent and component of gasoline produced in petroleum industries, have been explored on normal (HaCaT) and cancerous (HeLa) epithelial cells. Besides morphological alterations, impacts on viability, prime molecular expressions, and bioelectrical properties on exposure to different doses of isooctane were noted. Scanning electron microscopy and viability assay demonstrated remarkable structural alterations and cell death, respectively, in HaCaT but not in HeLa. Transcriptomic and immunocytochemical studies on E-cadherin expression also elucidated pronounced toxic effects on HaCaT. Remarkable changes on the bioelectrical properties (e.g., impedance and phase angle) of the HaCaT, in contrast to HeLa, at different temporal points on isooctane exposure also indicated cytotoxic effects in the former. Hence this study illustrated cytotoxicity of isooctane on HaCaT multidimensionally which was evaded by HeLa.

Drosophila cell fusion induced by wheat germ agglutinin

1975 ◽  
Vol 18 (1) ◽  
pp. 113-121
Author(s):  
R.M. Rizki ◽  
T.M. Rizki ◽  
C.A. Andrews
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Embryonic Cell ◽  
High Concentration ◽  
Drosophila Cell ◽  
Low Concentrations ◽  
Embryonic Cell Lines ◽  
Scanning Electron

The effects of wheat germ agglutinin on Drosophila embryonic cell lines growing on cover-glasses was examined by scanning electron microscopy. At low concentrations of the lectin (5-10 mug/ml), cells spread against the glass surface and fused to form syncytia. At high concentration, damage to the cell surface was evidenced as extensive membrane shrivelling and loss of surface microfilaments. Fusion also occurred under these conditions. There was some indication that the morphology of cells in division remains undisturbed by wheat germ agglutinin. The coalescence of cells and morphologic disotrtion induced by wheat germ agglutinin were not inhibited by N-acetylglucosamine, the hapten inhibitor of the lectin, under the conditions utilized in this study.

scholarly journals Proeryptotic Activity of 4-Hydroxynonenal: A New Potential Physiopathological Role for Lipid Peroxidation Products

Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 770
Author(s):  
Mario Allegra ◽  
Ignazio Restivo ◽  
Alberto Fucarino ◽  
Alessandro Pitruzzella ◽  
Sonya Vasto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Lipid Peroxidation ◽  
Scanning Electron Microscopy ◽  
Flow Cytometry ◽  
Endothelial Cells ◽  
Caspase 3 ◽  
Morphological Alterations ◽  
Signalling Molecule ◽  
Free Haemoglobin ◽  
Scanning Electron

Background: Eryptosis is a physiological, apoptosis-like death of injured erythrocytes crucial to prevent premature haemolysis and the pathological sequalae generated by cell-free haemoglobin. When dysregulated, the process is associated to several inflammatory-based pathologies. 4-Hydroxy-trans-2-nonenal (HNE) is an endogenous signalling molecule at physiological levels and, at higher concentrations, is involved in the pathogenesis of several inflammatory-based diseases. This work evaluated whether HNE could induce eryptosis in human erythrocytes. Methods: Measurements of phosphatidylserine, cell volume, intracellular oxidants, Ca++, glutathione, ICAM-1, and ceramide were assessed by flow cytometry. Scanning electron microscopy evaluated morphological alterations of erythrocytes. Western blotting assessed caspases. PGE2 was measured by ELISA. Adhesion of erythrocytes on endothelial cells was evaluated by gravity adherence assay. Results: HNE in the concentration range between 10–100 µM induces eryptosis, morphological alterations correlated to caspase-3 activation, and increased Ca++ levels. The process is not mediated by redox-dependent mechanisms; rather, it strongly depends on PGE2 and ceramide. Interestingly, HNE induces significant increase of erythrocytes adhesion to endothelial cells (ECs) that are in turn dysfunctionated as evident by overexpression of ICAM-1. Conclusions: Our results unveil a new physiopathological role for HNE, provide mechanistic details of the HNE-induced eryptosis, and suggest a novel mechanism through which HNE could exert pro-inflammatory effects.

Therapeutic efficacy of a newly synthesized benzimidazole compound BTP-OH against murine schistosomiasis mansoni

2020 ◽  
Vol 94 ◽  
Author(s):  
A. Taman ◽  
B. Mansour ◽  
M.Y. Youssef ◽  
S.M. Alhusseiny
Keyword(s):  
Electron Microscopy ◽  
Therapeutic Efficacy ◽  
Worm Burden ◽  
Mechanisms Of Action ◽  
Ultrastructural Changes ◽  
Egg Load ◽  
Future Studies ◽  
Schistosomiasis Mansoni ◽  
Total Worm Burden ◽  
Scanning Electron

Abstract Because of the increasingly emerging praziquantel resistance, there is a crucial need to develop new anti-schistosomal agents. This work was conducted to assess the therapeutic efficacy of a new benzimidazole compound (BTP-OH) in mice experimentally infected with Schistosoma mansoni. A total of 40 Swiss albino female mice were divided into an infected untreated group and three infected treated groups (using praziquantel and BTP-OH). The compound activity was evaluated through parasitological, histopathological and scanning electron microscopy studies. Praziquantel and BTP-OH at both doses significantly reduced male (75%, 42.67% and 61.08%, respectively), female (71.45%, 48.94% and 68.13%, respectively) and total worm burden (75.21%, 42.42% and 62.28%, respectively), as well as tissue egg load in the liver (71.22%, 42.12% and 66.04%, respectively). In oogram, praziquantel significantly increased the percentage of dead eggs (65.89%), while BTP-OH significantly reduced the percentage of immature eggs (30.43% and 19.64%). BTP-OH significantly diminished granuloma count (33.87% and 44.77%) and diameter (39.23% and 49.40%), and caused ultrastructural changes in the tegument of adult schistosomes. This study provides evidence for the schistosomicidal efficacy of BTP-OH. However, future studies are needed to elucidate the full mechanisms of action and effects of BTP-OH on other human schistosomes.

scholarly journals Structural and Optical Investigations of Heterostructures Based on AlxGa1-xAsyP1-y:Si Solid Solutions Obtained by MOCVD

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
P. V. Seredin
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Epitaxial Films ◽  
X Ray Diffraction ◽  
Energy Characteristics ◽  
X Ray ◽  
Epitaxial Heterostructures ◽  
High Concentrations ◽  
Scanning Electron

We investigated MOCVD epitaxial heterostructures based on AlxGa1−xAs ternary solid solutions, obtained in the range of compositions x~0.20–0.50 and doped with high concentrations of phosphorus and silicon atoms. Using the methods of high-resolution X-ray diffraction, scanning electron microscopy, X-ray microanalysis, Raman spectroscopy, and photoluminescence spectroscopy we have shown that grown epitaxial films represent five-component (AlxGa1−xAs1−yPy)1−zSiz solid solutions. The implementation of silicon in solid solution with a concentration of ~ 0.01 at.% leads to the formation of the structure with deep levels, DX centers, the occurrence of which fundamentally affects the energy characteristics of received materials.

scholarly journals Synthesis of Hydroxyapatite-Ag Composite as Antimicrobial Agent

Dose-Response ◽  
2020 ◽  
Vol 18 (3) ◽  
pp. 155932582095134
Author(s):  
Pamela Nair Silva-Holguín ◽  
Simón Yobanny Reyes-López
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Drug Resistance ◽  
Silver Nanoparticles ◽  
Antimicrobial Agents ◽  
Sol Gel ◽  
Antimicrobial Properties ◽  
Low Concentrations ◽  
Silver Nanocomposite ◽  
Scanning Electron

Innovative and improved antimicrobial agents by nanotechnology are developed to control and mitigation of resistant microorganisms. Nanoparticles of metals or oxide metals be able to be toxic to bacteria, demonstrating biocidal behaviors at low concentrations. The integration of silver nanoparticles in ceramic matrices has enhanced the antimicrobial performance, resulting in the search for new composites with improved bactericidal properties. The aim of this study was to prepare and characterize hydroxyapatite-silver nanocomposite and evaluate its antimicrobial properties against various Gram-positive and negative bacteria related to drug-resistance infections. Hydroxyapatite nanopowders were produced by sol-gel and silver nanoparticles were synthesized by reduction of Ag+ions with the simple addition of gallic acid. Hydroxyapatite-silver composite (HAp-AgNPs) was prepared by adsorption of AgNPs at several concentrations. The results of UV–visible spectroscopy, dynamic light scattering, and transmission scanning electron microscopy revealed the existence of AgNPs with diameters around 6 nm. Scanning electron microscopy and energy dispersive X-ray spectroscopy corroborated the presence of silver disseminated over the surface of hydroxyapatite nanopowders. All HAp-AgNPs composites demonstrated excellent antibacterial effect even at lower silver concentration. HAp-AgNPs composites have a higher possibility for medical applications focused no the control of microorganisms with drug-resistance.

scholarly journals Damage of the Bacterial Cell Envelope by Antimicrobial Peptides Gramicidin S and PGLa as Revealed by Transmission and Scanning Electron Microscopy

2010 ◽  
Vol 54 (8) ◽  
pp. 3132-3142 ◽  
Author(s):  
Mareike Hartmann ◽  
Marina Berditsch ◽  
Jacques Hawecker ◽  
Mohammad Fotouhi Ardakani ◽  
Dagmar Gerthsen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Antimicrobial Peptides ◽  
Lipid Membrane ◽  
Ultrastructural Changes ◽  
Morphological Alterations ◽  
Bacterial Membranes ◽  
E Coli ◽  
Gramicidin S ◽  
Scanning Electron

ABSTRACT Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the ultrastructural changes in bacteria induced by antimicrobial peptides (AMPs). Both the β-stranded gramicidin S and the α-helical peptidyl-glycylleucine-carboxyamide (PGLa) are cationic amphiphilic AMPs known to interact with bacterial membranes. One representative Gram-negative strain, Escherichia coli ATCC 25922, and one representative Gram-positive strain, Staphylococcus aureus ATCC 25923, were exposed to the AMPs at sub-MICs and supra-MICs in salt-free medium. SEM revealed a shortening and swelling of the E. coli cells, and multiple blisters and bubbles formed on their surface. The S. aureus cells seemed to burst upon AMP exposure, showing open holes and deep craters in their envelope. TEM revealed the formation of intracellular membranous structures in both strains, which is attributed to a lateral expansion of the lipid membrane upon peptide insertion. Also, some morphological alterations in the DNA region were detected for S. aureus. After E. coli was incubated with AMPs in medium with low ionic strength, the cells appeared highly turgid compared to untreated controls. This observation suggests that the AMPs enhance osmosis through the inner membrane, before they eventually cause excessive leakage of the cellular contents. The adverse effect on the osmoregulatory capacity of the bacteria is attributed to the membrane-permeabilizing action of the amphiphilic peptides, even at low (sub-MIC) AMP concentrations. Altogether, the results demonstrate that both TEM and SEM, as well as appropriate sample preparation protocols, are needed to obtain detailed mechanistic insights into peptide function.

Influence of Molybdenum and Boron Addition on Fracture of P/M Parts

2016 ◽  
Vol 682 ◽  
pp. 265-269
Author(s):  
Małgorzata Perek-Nowak ◽  
Joanna Karwan-Baczewska
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tensile Test ◽  
Hydrogen Atmosphere ◽  
Transgranular Fracture ◽  
Boron Addition ◽  
Low Concentrations ◽  
Boron Particles ◽  
Type Of Fracture ◽  
Scanning Electron

Samples made of iron powder with addition of 1.5 and 2% of molybdenum and 0-0.6% of boron were compacted at 600 MPa and sintered at 1200°C for 60 minutes in hydrogen atmosphere after mixing in Turbula mixer. The samples were deformed in a tensile test till rupture. The effect of molybdenum and boron on topography of fracture is discussed. It is noted that the sintering mechanism changes upon addition of boron particles into Fe-Mo alloy. The fractures of the studied samples were observed by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The addition of Mo influences the change of fracture to ductile type. The type of fracture is brittle with Mo and borides segregating to grain boundaries. In the alloys with low concentrations of molybdenum boron induces brittle transgranular fracture.

Sign in / Sign up

Export Citation Format

Share Document