Contribution Of Electron Microscopy Research Articles

Characterization of Drug Delivery Systems by Transmission Electron Microscopy.

The contribution of electron microscopy, and here, in particular transmission electron microscopy (TEM), to the formulation and understanding of the biological action of drug delivery systems has led to a better insight into the design principles of drug delivery systems. TEM can be applied for particle characterization, for the visualization of the uptake and intracellular pathways of drug vehicles in cells and tissues and more recently can be also applied for the high-resolution investigation of drug-receptor interactions with near-atomic resolution. This chapter introduces basic techniques to optimize imaging quality of soft matter samples, highlights possibilities to study certain aspects of drug delivery applications, and finally provides a short introduction to high-resolution characterization possibilities which recently emerged.

Contribution of Electron Microscopy to the Clinicopathologic Diagnosis in Childhood Glomerular Renal Diseases

Background: Electron microscopy (EM) provides another diagnostic assessment of glomerular lesions in addition to light and fluorescent microscopy. Objectives: We evaluated the contribution of diagnostic EM in childhood glomerular diseases. Patients and methods: Forty-eight renal biopsies which were assessed by EM between 2000 and 2014 were evaluated. Results: There were 21 (44%) females and 27 (56%) males, ages ranged between 6 and 204 months. EM findings were compatible with light and immunofluorescence microscopy in 65%, made additional contributions to diagnosis in 31% (especially in focal segmental glomerulosclerosis, Alport disease, membranoproliferative glomerulonephritis, dense deposit disease, thin basement membrane disease, and nephronophthisis), and was non-contributory in 4%. Conclusion: Electron microscopic evaluation supports other histopathological diagnoses in most cases, contributes additional diagnostic information in pediatric glomerular disease, especially in FSGS, thin glomerular basement membrane nephropathy, Alport disease, MPGN, and dense deposit disease, and its utilization should clinically justify the increase in cost and testing time.

The Contribution of Electron Microscopy to the Characterization of Soft Tissue Fibrosarcomas

In recent years, with the application of immunohistochemical and cytogenetic methods, numerous lesions formerly diagnosed as fibrosarcoma were reclassified as other malignant soft tissue tumors, and therefore conventional fibrosarcoma has largely become a diagnosis of exclusion. On the other hand, several new entities belonging to the group of fibrosarcomas have been characterized, including low-grade fibromyxoid sarcoma / hyalinizing spindle cell tumor with giant rosettes, sclerosing epithelioid fibrosarcoma, acral myxoinflammatory fibroblastic sarcoma, and the epithelioid variant of myxofibrosarcoma. Electron microscopy has contributed to the identification of the fibroblastic phenotype in these fibrosarcoma variants and still retains a central role in the differential diagnosis of these soft tissue sarcomas, thus helping to render specific diagnoses and to broaden the spectrum of fibrosarcoma variants.

Value of Electron Microscopy in the Diagnosis of Glomerular Diseases

To evaluate the contribution of electron microscopy to the final diagnosis of glomerulopathies, the authors established a prospective study during the first semester of 2006. A total of 52 kidney biopsies were performed with 3 samples for light microscopy, immunofluorescence, and electron microscopy. Among these renal biopsies, only 20 were examined with electron microscopy because the diagnosis made on the basis of conventional methods had remained unclear or doubtful. In 18 cases, electron microscopy was undertaken for the investigation of primary kidney disease. The 2 remaining cases were transplant biopsies. In this series of 20 patients, there were 3 children with an average age of 9 years and 17 adults with an average age of 35.5 years. Fifteen patients (75%) were nephrotic. The study revealed that electron microscopy was essential for diagnosis in 8 cases (40%) and was helpful in 12 cases (60%). In conclusion, the results showed that the ultrastructural study provides essential or helpful information in many cases of glomerular diseases, and therefore electron microscopy should be considered an important tool of diagnostic renal pathology. As was recommended, it is important to reserve renal tissue for ultrastructural study unless electron microscopy can be routinely used in all biopsies. Thus, this technique could be performed wherever a renal biopsy has to be ultrastructurally evaluated.

From structure to mechanism: electron crystallographic studies of bacteriorhodopsin.

Bacteriorhodopsin is a protein found in cell membranes of the organism H. salinarum, where it functions as an efficient light-driven proton pump. Because bacteriorhodopsin is one of the simplest ion pumps known in biology, it has been the subject of intensive investigations over the last three decades, using methods spanning the range from femtosecond spectroscopy and crystallography to biochemistry and molecular biology. Here, we focus on the structural basis for the function of this protein, with primary emphasis on the contributions of electron microscopy and crystallography towards unravelling the mechanism of vectorial proton pumping.

Contribution of Electron Microscopy to Understanding Cellular Differentiation in Mesenchymal Tumors of the Gastrointestinal Tract: A Study of 82 Tumors

Eighty-two mesenchymal tumors of the gastrointestinal tract were examined by electron microscopy for the purposes of subtyping for diagnostic precision and of understanding cellular differentiation. Tumors were subclassified into leiomyoma/leiomyosarcoma, tumors of the interstitial cell of Cajal (equivalent to traditionally defined GISTs [Miettinen et al. Hum Pathol. 1999; 30:1213-1220; Mod Pathol. 2000; 13:1134-1142]), gastrointestinal autonomic nerve tumors (GANTs), and fibroblastic and myofibroblastic tumors, using criteria from the literature. Leiomyoma/leiomyosarcoma were diagnosed by myofilaments, attachment plaques, plasmalemmal caveolae, and lamina; GIST by processes or cell bodies full of intermediate filaments, solitary focal densities amid intermediate filaments, attachment plaques with incomplete lamina, scarce myofilaments, and smooth endoplasmic reticulum; GANTs by neuroendocrine granules, cell bodies/processes full of intermediate filaments (more rarely microtubules), and smooth endoplasmic reticulum; fibroblastic/myofibroblastic tumors by abundant rough endoplasmic reticulum, myofilaments, and fibronexuses. Seventy-three tumors (89%) were successfully subclassified, as 5 leiomyoma/leiomyosarcoma (6%), 36 GISTs (44%), 22 GANTs (27%), 10 fibroblastic and myofibroblastic tumors (12%). Results indicated overlap between poorly differentiated leiomyosarcoma and GIST, and between GIST and GANT. GANT is emphasized as a neuronal tumor identifiable by electron microscopy, and thereby distinguishable from GIST.

Value of Electron Microscopy in the Diagnosis of Childhood Nephrotic Syndrome

The value of the ultrastructural study of the renal biopsy was investigated in a series of pediatric patients with nephrotic syndrome. Forty-eight cases of renal biopsies with clinical data were reviewed and divided into diagnostic groups. The contribution of electron microscopy to the final diagnosis was graded as essential — diagnosis could not be reached without it; supportive — it increased the level of confidence in the final diagnosis; and noncontributory. In this series of renal biopsies from 48 children with nephrotic syndrome resistant or nonresponsive to therapy, the mostfrequent diagnosis was minimal change disease, present in 42%of the patients. The contribution of the electron microscopic study to the final diagnosis was essential in 73%of the series, and was supportive in a further 27%.Therefore, it is concluded that the ultrastructural study was an essential component in the study of the renal biopsy in children with nephrotic syndrome, suggesting that electron microscopy needs to continue to be performed for all these patients.

The Continuing Value of Electron Microscopy in Surgical Pathology

For decades, transmission electron microscopy has played a valuable diagnostic role in surgical pathology. The continuing importance of electron microscopy, however, can be debated, given the major advances that have occurred in immunohistochemistry and other techniques. Electron microscopy retains excellent educational potential and broad research applicability, and it continues to be a necessity for the evaluation of a small subset of surgical pathology cases, such as renal biopsies and cilia specimens. The real controversy, then, centers on the contribution of electron microscopy in the evaluation of neoplasms. The opinion of many experts indicates that electron microscopy is still vital in the diagnostic assessment of some neoplasms, and that both electron microscopy and immunohistochemistry are more powerful when viewed as complementary rather than competitive techniques. For electron microscopy to be used to its potential, however, electron microscopists must function effectively as consultants. When optimally applied, electron microscopy remains an essential diagnostic tool.

Contributions of Electron Microscopy and Single-Particle Techniques to the Determination of the Ryanodine Receptor Three-Dimensional Structure

The ryanodine receptor is the main intracellular calcium release channel from the sarcoplasmic reticulum in striated muscle. It is the largest ion channel known, composed of four identical major subunits of 565 kDa and four smaller 12-kDa subunits, identified as FK-506 binding protein. The successful isolation of the ryanodine receptor together with the development of cryoelectron microscopy and single-particle image processing techniques have enabled major progress to be made in the determination of the receptor's structure over the past decade. Three-dimensional reconstruction shows the receptor to be composed of two main parts, a large square shaped cytoplasmic assembly and a smaller transmembrane assembly. The cytoplasmic assembly has an unusual architecture in which about 10 domain-like structures are interconnected in a loosely packed manner. Subsequent studies have started to reveal conformational changes associated with channel gating and the localization of binding sites for some proteins with which the receptor interacts (calmodulin, and FK-506 binding protein). It is becoming clear that long-range induced conformational changes must be involved in the mechanisms of modulation of the receptor's gating properties.

Characterization of the damage to membranes caused by bacterial cytolysins

The damage to cell membranes caused by bacterial cytolysins has been studied for many years. In this review, we attempt to summarize the historical contribution of electron microscopy to our understanding of the modes of action of pore-forming and channel-forming toxins. We describe the ways in which these toxins form holes in membranes by binding to and forming oligomers on biological membranes. We also introduce the new technique of electron spectroscopic imaging (ESI) with an imaging plate (IP), which has been used to analyse the mechanisms of membrane damage by cytolysins.

Structural polymorphism of crystalline polymers: Electron and atomic force microscopy contributions

AbstractThe contribution of electron microscopy, electron diffraction and atomic force microscopy to the elucidation of the structure of polymers ‐in particular helical polyolefins‐ is briefly presented. Particular emphasis is put on the elucidation of rather subtle aspects of the structure, such as disorders introduced by packing of up and down, or left and right handed helices in the lattice. The spectroscopic and diffraction informations are evaluated and compared.

Pathology of the salivary glands: The contribution of electron microscopy

Electron microscopy has a limited role in the diagnosis of primary salivary gland tumors, although it can be helpful in metastatic lesions of possible salivary gland origin. The diversity of subtypes in salivary gland tumors, as well as the range of histomorphology within any one subtype, is unparalleled in any other human tumor. This and their relative infrequency causes diagnostic problems for pathologists. Ultrastructural techniques have been of major importance in determining the inter-relationship of these tumors for classification purposes, revealing the subtle variations in common cellular differentiation pathways, determining the organization of tumor cells, and displaying the importance of extracellular matrix materials in establishing diagnostic criteria for each of the many subtypes. Electron microscopy has also been valuable in non-neoplastic salivary gland disease and has an increasing role in experimental studies involving tissue from human and animal salivary parenchyma.

French contribution of electron microscopy to bacteriology

French contribution of electron microscopy to bacteriology

French contribution of electron microscopy to bacteriology

French contribution of electron microscopy to bacteriology

Contribution of electron microscopy to the classification of minimally differentiated acute leukemias in children.

In recent multiparameter studies, ultrastructural morphology and cytochemistry of undifferentiated or minimally differentiated acute leukemia’s have been investigated (Lee et al. 1987; Matutes et al. 1988; Campana et al. 1990; Van Wering et al. 1990; Heil et al. 1991). Detection of myeloperoxidase (MPO) and platelet peroxidase (PPO) at the ultrastructural level appeared to be useful for myeloid leukemia’s (Bennett et al. 1991) and supportive for the diagnosis of megakaryocytic leukemias (Breton-Gorius et al. 1978; Bennett et al. 1985). We investigated 12 light-microscopically unclassifiable acute childhood leukemia’s by immunological marker analysis and by electron microscopy (EM), including peroxidase cytochemistry. The combined results appeared to provide information to diagnose conclusively cases of minimally differentiated acute myeloid leukemia’s (AML M0; Bennett et al. 1991) and acute megakaryoblastic leukemia (AML M7; Bennett et al. 1985).

Contributions of electron microscopy to our understanding of implantation and cell layer formation in primates

Contributions of electron microscopy to our understanding of implantation and cell layer formation in primates

Quantitative electron microscopic analysis of DNA-protein interactions.

Electron microscopy offers a unique potentiality to visualize individual molecules. For the last 30 years it has been used to study the structure and the interactions of various biological macromolecules. The contribution of electron microscopy is important because of its capacity to demonstrate the existence of conformational structures such as kinks, bents, loops, etc., either on naked DNA, or on DNA associated with various proteins or ligands. Increasing interest was given to such observations when it was found that they provide a direct visualization of interacting molecules involved in DNA metabolism and gene regulation. Technical advances in the preparation of the specimens, their observation in the electron microscope, and the image processing by computers have allowed the shifting from qualitative to quantitative analysis, as illustrated by a few examples from our laboratory.

Contributions of electron microscopy towards the understanding of flavivirus replication process

The techniques of electron microscopy was extensively used in our study on flavivirus replication. The initial event of attachment and entry of the virus was visualised (Fig 1). It revealed that virus (Vi) particle attachment (double arrow) was most likely receptor-mediated. Entry was through clathrin-coated endocytotlc vesicles (Eve). Uncoating of the virus envelope (short arrows) seemed to occur within the endocytotic vesicles.After entry and during replication, there are several virus-induced changes (Fig 2). Three most prominent features are the formation of vesicles (Ve), the microtubule paracrystals (Pc) and the proliferation of the endoplasmic reticulum (ER). These components are always in close vicinity to each other and could be the replication complex for the virus.

Contributions of Electron Microscopy to Environmental Science

Heightened concern about the environment, and particularly the increasing rate of dispersion of toxic substances and irritants has placed severe demands on analytical techniques to define the nature and occurrence of potentially hazardous constituents and devise control technologies as well as to determine the risk to human life. In many cases, environmental contamination involves the presence of very fine particulates, which may pose some health risk in their own right or may simply serve as carriers for hazardous chemicals that fall within the respirable range, i.e. 10 microns or less in major dimension. Electron microscopy, widely used to observe and identify fine particulates in the atmosphere, has already contributed significantly to environmental science but advances in instrumentation are needed to overcome technical and economic limitations to its use.Sources of Environmental ParticulatesAtmosphere particulates, popularly considered to originate primarily from heavy industrial operations such as mining, primary metal production or power generation, can also come from natural sources such as volcanoes, forest fires, silt residue from flooding, and botanical emissions (spores, pollen). Paniculate pollutants also derive from smoking, debris from road wear of automobile and truck tires, fragmentation of asbestos-containing insulation and building materials, food processing, earth moving operations, open burning of agricultural residues and waste dumps and unfiltered emissions from incinerators.

Contributions of Electron Microscopy to Biology and Medicine

In the development of the biological and medical sciences, morphology has traditionally served as pacemaker, from the Renaissance on when Vesalius founded Anatomy as a science.The invention of the microscope brought observation into the range of invisible structures. This ended around the middle of the last century when the cell was discovered as the fundamental unit of living matter, and also as the site of disease, causing “numoral” pathology to be replaced by cellular pathology (Virchow).At the same time, microscopic methods had reached their limit. The chemical revolution stepped in and biochemistry became the pacemaker in biology and medicine; we seemed to move back to “humoral pathology”.When electron microscopy was applied in biological studies after 1950 a new “invisible world” was discovered: the power of morphological observation was extended to the molecular level. Membranes were discovered as boundaries of the cell and as barriers between compartments: cell function was seen as a highly ordered process. Step by step with ever more refined techniques, cellular organization was unravelled. Today's picture is that of a totally ordered cell with precise relationships to its neighbors. The structure of bacteria and viruses and the pattern of their interaction with cells and tissues was revealed. The diversity of cells became reduced to variations over a common basic scheme.