scholarly journals In Vitro Activities of MMV Malaria Box Compounds against the Apicomplexan Parasite Neospora caninum, the Causative Agent of Neosporosis in Animals

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1460
Author(s):  
Joachim Müller ◽  
Pablo A. Winzer ◽  
Kirandeep Samby ◽  
Andrew Hemphill
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Neospora Caninum ◽  
Chemotherapeutic Agents ◽  
Apicomplexan Parasite ◽  
In Vivo Studies ◽  
Transmission Electron ◽  
Malaria Box ◽  
Caninum Tachyzoites

(1) Background: Neospora caninum is a major cause of abortion in cattle and represents a veterinary health problem of great economic significance. In order to identify novel chemotherapeutic agents for the treatment of neosporosis, the Medicines for Malaria Venture (MMV) Malaria Box, a unique collection of anti-malarial compounds, were screened against N. caninum tachyzoites, and the most efficient compounds were characterized in more detail. (2) Methods: A N. caninum beta-galactosidase reporter strain grown in human foreskin fibroblasts was treated with 390 compounds from the MMV Malaria Box. The IC50s of nine compounds were determined, all of which had been previously been shown to be active against another apicomplexan parasite, Theileria annulata. The effects of three of these compounds on the ultrastructure of N. caninum tachyzoites were further investigated by transmission electron microscopy at different timepoints after initiation of drug treatment. (3) Results: Five MMV Malaria Box compounds exhibited promising IC50s below 0.2 µM. The compound with the lowest IC50, namely 25 nM, was MMV665941. This compound and two others, MMV665807 and MMV009085, specifically induced distinct alterations in the tachyzoites. More specifically, aberrant structural changes were first observed in the parasite mitochondrion, and subsequently progressed to other cytoplasmic compartments of the tachyzoites. The pharmacokinetic (PK) data obtained in mice suggest that treatment with MMV665941 could be potentially useful for further in vivo studies. (4) Conclusions: We have identified five novel compounds with promising activities against N. caninum, the effects of three of these compounds were studies by transmission electron microscopy (TEM). Their modes of action are unknown and require further investigation.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

Ultrastructures of Epibiotic Suctorian, Tokophrya huangmeiensis 

Zootaxa ◽  
2018 ◽  
Vol 4521 (1) ◽  
pp. 145
Author(s):  
URFA BIN TAHIR ◽  
DENG QIONG ◽  
WANG ZHE ◽  
LI SEN ◽  
LIU YANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Structural Changes ◽  
Small Subunit ◽  
Free Living ◽  
Transmission Electron ◽  
Small Subunit Ribosomal Dna ◽  
Ribosomal Dna Sequence ◽  
Freshwater Ciliates

Tokophrya species are either free-living or facultative ectosymbiotic suctorians associated with copepods, isopods, mysids, decapods and amphipods. Tokophrya huangmeiensis in particular is found to be epizoic with the redclaw crayfish Cherax quadricarinatus Von Martens, 1868, which has been observed as part of an ongoing investigation of freshwater ciliates biodiversity in Huanggang, Hubei, China (Tahir et al. 2017). This first study on T. huangmeiensis based on morphological features using light microscopy and small subunit ribosomal DNA sequence (Tahir et al. 2017), suggested that more detailed descriptions on the physiological and structural changes of this species should be done. Thus, in this study, we looked at the ultrastructures of T. huangmeiensis using electron microscopy, including both scanning (SEM) and transmission electron microscopy (TEM). 

scholarly journals In VitroEffects of Novel Ruthenium Complexes in Neospora caninum and Toxoplasma gondii Tachyzoites

2013 ◽  
Vol 57 (11) ◽  
pp. 5747-5754 ◽  
Author(s):  
Fabienne Barna ◽  
Karim Debache ◽  
Carsten A. Vock ◽  
Tatiana Küster ◽  
Andrew Hemphill
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Toxoplasma Gondii ◽  
Neospora Caninum ◽  
Ruthenium Complexes ◽  
Term Treatment ◽  
Content Type ◽  
Transmission Electron ◽  
Long Term Treatment

ABSTRACTUpon the screening of 16 antiproliferative compounds againstToxoplasma gondiiandNeospora caninum, two hydrolytically stable ruthenium complexes (compounds 16 and 18) exhibited 50% inhibitory concentrations of 18.7 and 41.1 nM (T. gondii) and 6.7 and 11.3 nM (N. caninum). To achieve parasiticidal activity with compound 16, long-term treatment (22 to 27 days at 80 to 160 nM) was required. Transmission electron microscopy demonstrated the rapid impact on and ultrastructural alterations in both parasites. These preliminary findings suggest that the potential of ruthenium-based compounds should thus be further exploited.

The structural changes of polycrystalline film C60/C70: Ni caused by Ni diffusion

1996 ◽  
Vol 11 (12) ◽  
pp. 3146-3151 ◽  
Author(s):  
E. Czerwosz ◽  
P. Byszewski ◽  
R. Diduszko ◽  
H. Wronka ◽  
P. Dluźewski ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Structural Changes ◽  
Thermal Conditions ◽  
Vacuum Deposition ◽  
X Ray Diffraction ◽  
Polycrystalline Structure ◽  
X Ray ◽  
Transmission Electron

C60/C70: Ni films with 1.5 wt. % Ni concentration obtained by vacuum deposition under different thermal conditions have been investigated. The structural changes of the layers were investigated by transmission electron microscopy, electron and x-ray diffraction, and Raman spectroscopy. The polycrystalline structure was detected for the layers grown at approximately 450 K on the substrate. At elevated temperature and maintained temperature gradient on the substrate during the process, the changes of the layer's structure and the formation of Ni microcrystals were observed. The Ni microcrystals (5–10 nm in the diameter) and the elongated shapes dimensioned 10 × 150 nm were perceived.

Techniques for Characterising Artificial Layer Structures using Transmission Electron Microscopy

1987 ◽  
Vol 103 ◽  
Author(s):  
W. M. Stobbs
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Dark Field ◽  
Multilayer Structures ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Layer Structures ◽  
Quantitative Characterisation ◽  
Field Imaging

ABSTRACTT.E.M. methods are described for the quantitative characterisation of the compositional and structural changes at interfaces and in homo- and hetero-phase multilayer structures. Many of the newer approaches described including the Fresnel and Centre Stop Dark Field Imaging Methods were developed specifically for such characterisations. The range of applications of each of the techniques is assessed as is the importance of delineating the limiting effects of inelastic and inelastic/elastic multiple scattering.

Functional and structural correlations of individual αIIbβ3 molecules

Blood ◽  
2004 ◽  
Vol 104 (13) ◽  
pp. 3979-3985 ◽  
Author(s):  
Rustem I. Litvinov ◽  
Chandrasekaran Nagaswami ◽  
Gaston Vilaire ◽  
Henry Shuman ◽  
Joel S. Bennett ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Divalent Cation ◽  
Structural Changes ◽  
Laser Tweezers ◽  
Structural Rearrangements ◽  
Integrin Αiibβ3 ◽  
Open Conformation ◽  
Transmission Electron ◽  
Open Structures

Abstract The divalent cation Mn2+ and the reducing agent dithiothreitol directly shift integrins from their inactive to their active states. We used transmission electron microscopy and laser tweezers-based force spectroscopy to determine whether structural rearrangements induced by these agents in the integrin αIIbβ3 correlate with its ability to bind fibrinogen. Mn2+ increased the probability of specific fibrinogen-αIIbβ3 interactions nearly 20-fold in platelets, and both Mn2+ and dithiothreitol increased the probability more than 2-fold using purified proteins. Of 3 αIIbβ3 conformations, closed with stalks touching, open with stalks separated, and globular without visible stalks, Mn2+ and dithiothreitol induced a significant increase in the proportion of open structures, as well as structural changes in the αIIbβ3 headpiece. Mn2+ also increased the number of complexes between fibrinogen and purified αIIbβ3 molecules, all of which were in the open conformation. Finally, Mn2+ induced the formation of αIIbβ3 clusters that resulted from interactions exclusively involving the distal ends of the stalks. These results indicate that there is a direct correlation between αIIbβ3 activation and the overall conformation of the molecule. Further, they are consistent with the presence of a linked equilibrium between single inactive and single active αIIbβ3 molecules and active αIIbβ3 clusters. (Blood. 2004;104:3979-3985)

scholarly journals Enabling Lab-in-Gap Transmission Electron Microscopy at Atomic Resolution

2016 ◽  
Vol 24 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Xiao Feng Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Pole Piece ◽  
Large Area ◽  
Electrical Fields ◽  
Transmission Electron ◽  
Environmental Tem ◽  
New Generation

Abstract: Hitachi Lab-in-Gap transmission electron microscopy (TEM) technologies are introduced. The term Lab-in-Gap refers to a special function that allows in situ and in operando TEM studies of materials in gas or liquid environments while stimulations, such as thermal or electrical fields, are applied to the specimen sitting in the pole piece gap in a TEM system. Physical or chemical process can be activated and imaged in real time using TEM or other imaging modes. The new generation environmental TEM platform with large pole piece gap and advanced aberration correctors opens wide possibilities for integrating multiple stimuli sources as well as large-area, sub-Å resolution live imaging for dynamic structural changes.

Transmission electron microscopy study of Ge implanted into SiC

2002 ◽  
Vol 17 (2) ◽  
pp. 479-486 ◽  
Author(s):  
T. Gorelik ◽  
U. Kaiser ◽  
Ch. Schubert ◽  
W. Wesch ◽  
U. Glatzel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Structural Changes ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Means Of Transmission

Hexagonal 6H– and 4H–SiC wafers were implanted with (1−1.5) × 1016 cm−2 germanium ions at room temperature and at 700 °C with subsequent annealing between 1000 and 1600 °C. Structural changes in the SiC matrix were studied in detail by means of transmission electron microscopy (TEM). After implantation at room temperature the hexagonal SiC matrix becomes amorphous and, after annealing, recrystallizes into cubic SiC. The latter process was accompanied by the creation of voids and cracks. In case of high-temperature (700 °C) implantation, where amorphization was avoided, no polytype change in as-implanted and annealed SiC wafers was observed. In annealed samples nanocrystalline precipitates with high Ge content were observed in high-resolution TEM images.

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