Imaging domains in BaTiO3 single crystal nanostructures: comparing information from transmission electron microscopy and piezo-force microscopy

This article compares and contrasts information
obtained, using transmission electron microscopy (TEM)
and piezo-force microscopy (PFM), on domain configurations
adopted in single crystal lamellae of BaTiO3, that had
been cut directly from bulk using a focused ion beam
microscope with top and bottom surfaces parallel to
{100}pseudocubic. Both forms of imaging reveal domain
walls parallel to {110}pseudocubic, consistent with sets of 90
domains with dipoles oriented parallel to the two
\001[pseudocubic directions in the plane of the lamellae.
However, the domain width was observed to be dramatically
larger using PFM than it was using TEM. This suggests
significant differences in the surface energy densities
that drive the domain formation in the first place, that could
relate to differences in the boundary conditions in the two
modes of imaging (TEM samples are imaged under high
vacuum, whereas PFM imaging was performed in air).
Attempts were made to map local dipole orientations
directly, using a form of ‘vector’ PFM. However, information
inferred was largely inconsistent with the known
crystallography of the samples, raising concern about the
levels of care needed for accurate interpretation of PFM
images.

Is Reinke's Edema a Precancerous Lesion? Histological and Electron Microscopic Aspects

The objectives of this study were to evaluate morphologic alterations and precancerous lesions in Reinke's edema. Patients included were 54 smokers with bilateral Reinke's edema submitted to surgery in the Otolaryngology Department, Botucatu Medical School, São Paulo State University, Brazil, between 2002 and 2006. All specimens were evaluated by light microscopy and five contralateral lesions were also evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The main histological alterations were edema (100%), inflammation (81.48%), basal membrane (bm) thickening (77.77%), and vessel proliferation (75.92%). Epithelium alterations were classified as grade 0 (11.11%), grade 1 (70.37%), grade 2 (14.81%), and grade 3 (3.70%). In the case included in grade 3 classification, microinvasive carcinoma was detected. SEM showed epithelial surface with some cellular desquamation, few microridges, and a polished and impermeable surface aspect. TEM showed epithelial hyperplasia, basal cells with different sizes, widening of the intercellular spaces, abnormal desmosome architecture, thickening of the bm, some electron-dense vesicles, and points of interruption. The morphological alterations presented in this study are not specific to Reinke's edema but this lesion can be the site of different grades of dysplasia and carcinoma, justifying the importance of periodic laryngeal endoscopic exams and meticulous histological analysis.

The use of transmission electron microscopy and oocyte transfer to evaluate in vitro maturation of equine oocytes in different culture conditions

The current study evaluates the ability of equine oocytes matured in different conditions to undergo nuclear and cytoplasmic maturation.. After oocyte transfer, embryonic development was diagnosed at 1.5 and 90 days of gestation. For each group, immature oocytes obtained from slaughterhouse ovaries were matured in vitro (5 replicates). In experiment I, three different media were tested. HTF:BME, SOFaa, and TCM 199. In experiment 11, the HTF:BME was chosen as maturation medium containing pFSH, eFSH, or eFSH + eGH. Nuclear maturation was estimated after stripping the oocytes and staining with Hoechst 33342. The evaluation of cytoplasmic maturation was performed by transmission electron microscopy. For oocyte transfer, six non-cycling recipient mares were used, and 8 to 15 oocytes were transferred in each mare. In experiment I, the results showed no differences (P > .05) in nuclear maturation (MII) among experimental groups. The percentage of MII was 29.3 ( +/- 9.6), 23.4 ( +/- 8.4), and 13.5 ( +/- 12.4) for HTF:BME, SOF, and TCM, respectively. In experiment II, all media tested were efficient in inducing metaphase II. Also, no statistical differences (P > .05) were observed in percentages of nuclear maturation rates when porcine (37.1 +/- 22.4) or equine (25.8 +/- 8.2) FSH were used, or when eFSH + eGH was added to HTF:BME (29.4 +/- 12.3). The analysis of cytoplasmic morphology of oocytes cultured in TCM 199 and SOFaa showed signs of incomplete cytoplasmic maturation and premature cortical reaction. Meanwhile, oocytes cultured in HTF:BME medium presented cytoplasmic characteristics similar to those described by others for in vivo-matured oocytes. The addition of eFSH to the HTF:BME medium resulted in an improvement of cytoplasmic morphology. After oocyte transfer, two mares became pregnant, one from pFSH group and one from eFSH+eGH group. These results indicate that although in vitro matured equine oocytes are capable of fertilization and embryonic development, the percentage of competent oocytes is still low.

Cell enumeration and visualisation by transmission electron microscopy of Lactobacillus rhamnosus treated with cinnamon (Cinnamomum zeylanicum B.) essential oil

The use of essential oils (EOs) in functional foods containing probiotic microorganisms must consider the antimicrobial activity of these oils against beneficial bacteria such as Lactobacillus rhamnosus. This study aimed to evaluate the sensitivity of L. rhamnosus cultures treated with cinnamon EO through viable cell counts and visualisation by transmission electron microscopy. Cinnamon EO at a concentration of 0.04% had a bacteriostatic activity after 2 h of incubation. Although slight alterations were detected in the cell structure, this concentration was considered to be bactericidal, since it led to a significant reduction in cell numbers after 24 h. on the other hand, cinnamon EO at a 1.00% concentration decreased cell counts by 3 log units after 2 h incubation and no viable cell count was detected after 24 h. Transmission electron microscopy indicated that cells treated with 1.00% cinnamon EO were severely damaged and presented cell membrane disruption and cytoplasmic leakage.

Extruded vesicles of dioctadecyldimethylammonium bromide and chloride investigated by light scattering and cryogenic transmission electron microscopy

Combined dynamic and static light scattering (DLS, SLS) and cryogenic transmission electron microscopy (cryo-TEM) were used to investigate extruded cationic vesicles of dioctadecyldimethylammonium chloride and bromide (DODAX, X being Cl- or Br-). In salt-free dispersions the mean hydrodynamic diameter, D-h, and the weight average molecular weight, M-w, are larger for DODAB than for DODAC vesicles, and both D-h and M-w increase with the diameter (phi) of the extrusion filter. NaCl (NaBr) decreases (increases) the DODAB (DODAC) vesicle size, reflecting the general trend of DODAB to assemble as larger vesicles than DODAC. The polydispersity index is lower than 0.25, indicating the dispersions are rather polydisperse. Cryo-TEM micrographs show that the smaller vesicles are spherical while the larger ones are oblong or faceted, and the vesicle samples are fairly polydisperse in size and morphology. They also indicate that the vesicle size increases with phi and DODAB assembles as larger vesicles than DODAC. Lens-shaped vesicles were observed in the extruded preparations. Both light scattering and cryo-TEM indicate that the vesicle size is larger or smaller than phi when phi is smaller or larger than the optimal phi* approximate to 200 nm. (C) 2008 Elsevier B.V. All rights reserved.

A combined experimental and theoretical study on the formation of ag filaments on beta-Ag2MoO4 induced by electron irradiation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Valve disease in chronic venous disorders: a quantitative ultrastructural analysis by transmission electron microscopy and stereology

INTRODUCTION: The ultrastructure of venous valves and walls in chronic venous disease was investigated. METHODS: Consecutive patients were categorised into one of three groups (group A: patients with C1 venous disease in accordance with CEAP (Clinical severity, Etiology, Anatomy, Pathophysiology); group B: C2 and C3; group C: C4, C5 and C6). The terminal or preterminal valve and adjacent vessel wall was harvested from the great saphenous vein. Sections were examined with a transmission electron microscope. The volumes of elastin and of collagen per unit surface area of valve were assessed, as well as the surface endothelium of valve and vessel wall. RESULTS: The study population consisted of 17 patients. The elastin ratio was analysed by means of stereology. Mean values were: in group A, 0.45 μm3/m2; in group B, 0.67 μm3/m2; in group C, 0.97 μm3/m2. The ratio was similar for collagen (A, 15.7 μm3/m2; B, 26.8 μm3/m2; C, 30.1 μm3/m2). Surface analysis of the valve endothelium and the adjacent vessel wall endothelium showed a trend towards increasing damage with more severe disease. CONCLUSIONS: With progression of venous disease, the valve elastin content, assessed morphologically, seems to increase, and the endothelium of the venous valve and the vein wall tend to show more damage.

Assessing the expression of enterotoxigenic Escherichia coli-specific surface antigens in recombinant strains by transmission electron microscopy and immunolabeling

Infections with enterotoxigenic Escherichia coli (ETEC) are a major cause of travelers' diarrhea worldwide. Colonization of the small intestine mucosa is dependent on specific colonization factor antigens (CFA) and coli surface (CS) antigens. CFA/1, CS3, and CS6 are the most prevalent fimbrial antigens found in clinical isolates. The goal of our study was to visualize the morphology of CS3 and CS6 fimbriae in wild-type and recombinant E. coli strains by means of transmission electron microscopy in conjunction with negative staining and immunolabeling. Corresponding ETEC genes were cloned into E. coli K12 strain DH10B. Expression of fimbriae was dependent on culture conditions and sample handling. Specific immunolabeling of fimbriae unequivocally demonstrated the presence of all types of surface antigens investigated. Negative staining was effective in revealing CS3 but not CS6. In addition, this technique clearly demonstrated differences in the morphology of genetically and immunologically identical CS3 surface antigens in wild-type and recombinant strains. This paper provides a basis for the assessment of recombinant vaccines.

Visualization and quantitative analysis of nanoparticles in the respiratory tract by transmission electron microscopy

ABSTRACT: Nanotechnology in its widest sense seeks to exploit the special biophysical and chemical properties of materials at the nanoscale. While the potential technological, diagnostic or therapeutic applications are promising there is a growing body of evidence that the special technological features of nanoparticulate material are associated with biological effects formerly not attributed to the same materials at a larger particle scale. Therefore, studies that address the potential hazards of nanoparticles on biological systems including human health are required. Due to its large surface area the lung is one of the major sites of interaction with inhaled nanoparticles. One of the great challenges of studying particle-lung interactions is the microscopic visualization of nanoparticles within tissues or single cells both in vivo and in vitro. Once a certain type of nanoparticle can be identified unambiguously using microscopic methods it is desirable to quantify the particle distribution within a cell, an organ or the whole organism. Transmission electron microscopy provides an ideal tool to perform qualitative and quantitative analyses of particle-related structural changes of the respiratory tract, to reveal the localization of nanoparticles within tissues and cells and to investigate the 3D nature of nanoparticle-lung interactions.This article provides information on the applicability, advantages and disadvantages of electron microscopic preparation techniques and several advanced transmission electron microscopic methods including conventional, immuno and energy-filtered electron microscopy as well as electron tomography for the visualization of both model nanoparticles (e.g. polystyrene) and technologically relevant nanoparticles (e.g. titanium dioxide). Furthermore, we highlight possibilities to combine light and electron microscopic techniques in a correlative approach. Finally, we demonstrate a formal quantitative, i.e. stereological approach to analyze the distributions of nanoparticles in tissues and cells.This comprehensive article aims to provide a basis for scientists in nanoparticle research to integrate electron microscopic analyses into their study design and to select the appropriate microscopic strategy.