bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein‐A gold particles as markers in replica immunocytochemistry: high resolution electron microscope investigations of plasma membrane surfaces
Authors: Mannweiler K. , Hohenberg H. , Bohn W. , Rutter G. 
Published: August 2011

SUMMARYDue to their high atomic number contrast in transmission electron microscopy, gold particles are ideal markers in surface replicas of cultured cells. The suitability of protein‐A‐coated gold particles in replica immunocytochemistry for labelling surface antigens is demonstrated using measles virus‐infected cells as a model system. Labelled areas can easily be distinguished from unlabelled areas, and even markers positioned in the evaporation shadow of large structures can be accurately identified, which is a prerequisite for an exact quantification and mapping of antigen. In addition, the ultrastructure of labelled areas can still be visualized because of the small size of the marker.
Effect of substrate on freeze‐dried and shadowed protein structures
Authors: Trinick J. , Elliott A. 
Published: August 2011

SUMMARYMuscle thick filaments have been prepared for electron microscopy by a method involving freeze‐drying and shadowing. The same method applied to filaments on three different substrates gives rise to quite different appearances.The filaments on one of the substrates, hydrophilic carbon, show new detail not previously observed.
Electron dense granules and the role of buffers: artefacts from fixation with glutaraldehyde and osmium tetroxide
Authors: Hendriks Hans R. , Eestermans Inge L. 
Published: August 2011

SUMMARYElectron dense granules may appear in tissues after glutaraldehyde prefixation and osmium tetroxide postfixation. In order to determine the conditions under which the granules are formed various vehicles in pre‐ and post‐fixatives were tested on lymph node, thymus and heart.If granules appeared they were found in all cell types investigated, particularly in the nuclei. There was no difference in the distribution of the granules in the different compartments of these organs.The granules probably consist of complexes of glutaraldehyde, osmium and phosphate. The ultimate phosphate concentration in the tissues during the postfixation was shown to determine whether or not the artefacts appeared. Local conditions in the tissues also contributed to the appearance of the granules. It is concluded that phosphate buffers can be used in the double fixation procedure, but to avoid the granules in lymph node, thymus and heart, a concentration of 0·1 mol/l or less phosphate should be used. For brain and kidney other conditions apply.
Physical randomization of tissue architecture: an alternative to systematic sampling
Authors: Stringer B. M. J. , Wynford‐Thomas D. , Williams E. D. 
Published: August 2011

SUMMARYA method is described for the rapid and accurate quantitation of tissue morphology using rat thyroid as a model. Perfused‐fixed rat thyroid was diced into approximately thirty small pieces which were then randomly embedded in epon. Sections were taken at 500 μm intervals and stained with toluidine blue. Epithelial, follicular lumen and stromal components were quantified by a point counting technique. An analysis of variance was then performed on the data to determine whether there was any significant variation in the distribution of components between sections cut at different levels.No significant variation in any component was seen between sections for normal diced thyroid. This was also the case for diced thyroids of animals chronically treated with goitrogen to create a different physiological state. The method is therefore reliable even when marked changes in component distribution are induced.The physical randomization of tissue architecture by dicing, prior to embedding, greatly reduces the number of sections needed for the accurate morphometry of non‐randomly distributed tissues.
An improved method for combined autoradiography and histochemistry: the simultaneous detection of 6‐3H thymidine and acid phosphatase activity in cryostat sections of mouse thymus and duodenum
Authors: Lewis G. H. J. , Bowen I. D. 
Published: August 2011

SUMMARYA new method is described that enables the simultaneous detection of 6‐3H thymidine incorporation and acid phosphatase activity in the same tissue section. Histochemically, naphthol AS B1 released by tissue based acid phosphatase activity from the substrate naphthyl AS B1 phosphoric acid is coupled with a range of diazonium salts to produce insoluble azo dyes. The azo dye tests result in a particulate localization of lysosomal acid phosphatase and also label diffuse sources associated with cell death. The tests selected permit the application of photographic emulsion without the necessity of an inert barrier layer to separate the emulsion from the histochemically treated cryosections.The localization of 6‐3H thymidine incorporation and cell death in mouse thymus and duodenum is demonstrated and comparative counts estimating the distribution of 6‐3H thymidine incorporation and hydrolase labelled cell death in the thymus are presented. Young mouse thymus (5 weeks) was found to contain 1·36 ± 0·12% dying cells and 6·78 ± 0·03% thymidine incorporating cells, whilst old mouse thymus (53 weeks) was found to contain 2·34 ± 0·6% dying cells and 5·29 ± 0·37% thymidine incorporating cells.
Rapid and reliable method for diagnostic electron microscopy of faeces
Authors: Gbewonyo Armstrong J. K. 
Published: August 2011

SUMMARYFour methods are described for examining viruses in faeces by electron microscopy using negative staining. Faeces samples from a total of 180 patients with diarrhoea illnesses were processed for electron microscopy by the direct staining technique, pseudoreplica technique, microsolute concentration technique and by ultracentrifugation. Virus particles (including rotaviruses and adenoviruses) were found in fifty‐five (31%) samples when the results of all methods were combined. Bacteriophages were found in thirty of the samples which were read virus negative. Herpesviruses were also found in the faecal samples of two patients with diarrhoea illness. Parvovirus‐like particles were identified in one sample which was rotavirus and adeno‐virus positive. Calicivirus‐like particles were found in a sample which was adenovirus positive. With the direct staining technique thirty‐six (20%) samples contain virus particles; with micro‐solute concentration technique forty‐eight (27%) samples contain virus particles and with ultracentrifugation thirty‐eight (21%) contain virus particles.It is believed the microsolute concentration technique is rapid and more reliable than the pseudoreplica technique and ultracentrifugation method, and is a more preferable method for the diagnosis of faecal sample by electron microscopy.
A simple method for the handling and orientation of small specimens for electron microscopy
Authors: Carson J. , Lee R. M. K. W. , Forrest J. B. 
Published: August 2011

SUMMARYCyanoacrylic glue (Eastman 910) was used to affix small pieces of nasal scrapings to lens paper immediately before fixation in the glutaraldehyde. The lens paper not only served to hold specimens together so that they were not lost during tissue processing, but also functioned as a ‘landmark’ for the specimens, so that specimens could be oriented in a specific manner during embedding and subsequent sectioning.
A convenient culture chamber for observation and embedding of macrophage monolayers for transmission electron microscopy
Authors: Hackett Charles J. , Sullivan Kate 
Published: August 2011

SUMMARYA chamber adapted from a polypropylene test tube is described for the cultivation and processing of undisturbed monolayers of normal mouse macrophages for transmission electron microscopy (TEM). Peritoneal exudate cells are grown in the chambers on Visking dialysis membranes pretreated with Polybrene (Sigma Chemical Co.) and normal mouse serum. The cells are not further disturbed after adherence since the entire chamber, including dialysis membrane and cells, is processed for electron microscopy using standard material and protocols and the embedded dialysis membrane is readily oriented and thin‐sectioned. This method is efficient for studying adherent cells since growth can be nearly confluent and cells remain firmly attached throughout the manipulations. Since a transparent membrane is used, cells can also be observed with the light microscope at all stages prior to sectioning.
New instruments which facilitate rapid freezing at 83 K and 6 K
Authors: Escaig Jacques 
Published: August 2011

SUMMARYWe have developed three instruments to freeze different biological specimens for various purposes in the easiest and most economical way: a punching device, a rapid immersion device and a device to freeze the specimens against a copper block cooled by liquid helium. Cooling rate measurements are made by a thin flat thermocouple. Freezing against a copper block cooled down to 4 K gives cooling rates 3–5 times higher than freezing by immersion into propane at 85 K.
A low X‐ray background low temperature specimen stage for biological microanalysis in the TEM†
Authors: Nicholson W. A. P. , Biddlecombe W. H. , Elder H. Y. 
Published: August 2011

SUMMARYThe side entry specimen stage described in this paper is a development of a specimen stage for use at room temperature in the JEOL JEM 100 and 200 series transmission electron microscopes. The earlier specimen stage was designed to ensure that the extraneous instrumental contribution to thin specimen X‐ray spectra is both small and quantifiable. As well as having a low X‐ray background the new stage will also maintain the specimen at temperatures sufficiently low (down to 100 K) to minimize the loss of organic material due to electron irradiation. A new anticontaminator which provides a clean low temperature environment for the specimen stage is also described.
Thin frozen‐dried cryosections and biological X‐ray microanalysis
Authors: Barnard Tudor 
Published: August 2011

SUMMARYThe application of X‐ray microanalysis to problems of cell physiology required the development of methods to retain diffusible substances within the subcellular compartments that they occupied in vivo.Several groups have developed methods of rapidly freezing small samples in ways that minimize mechanical traumae and ice crystal formation. This provides a narrow zone from which cryosections, believed to be representative of the in vivo distribution of electrolytes, can be cut.The production of thin (less than 0·5 μm) cryosections that are apparently free of diffusion can be routinely performed when temperature parameters are kept below 173 K. Efficient cryosectioning requires several modifications to commercially available machines, in order to improve the ease and reliability with which various manipulations can be carried out.Initial attempts to localize calcium at the subcellular level were disturbed by the use of mechanically damaged specimens and by insufficiently cold conditions in the cryochamber. Such sections indicated that mitochondria were calcium‐rich organelles.When tissue freezing and cryosectioning were performed under optimized conditions, mitochondrial calcium was so low as to be quantifiable only with difficulty. Available microanalytical results show that ER‐rich cytoplasm and terminal cisternae of the sarcoplasmic reticulum seem to contain higher levels of calcium than mitochondria. Nuclei and secretory granules also contain more calcium than mitochondria.
A computer system for on‐line image capture and analysis
Authors: Skarnulis A. J. 
Published: August 2011

SUMMARYA computer control system for electron microscopy is proposed; it consists of functionally distinct microprocessors communicating via a central microprocessor (the supervisor) by direct memory access or a common data bus. The control functions such as digital beam scan, accelerating voltage, focusing, etc., are controlled by distributed microprocessors under the direction of the supervisory microprocessor. The system includes a framestore for image storage and a special high speed processor that contains a microcode library of functions. The system is used for interactive real‐time image analysis by comparison of calculated images and processed experimental images.
Interactive image processing with an off‐line minicomputer: organization, performance and applications
Authors: Saxton W. O. , Koch T. L. 
Published: August 2011

SUMMARYA recently established facility for interactive image processing is described, primarily from the point of view of the system's hardware organization and the special purpose software provided to support it. The performance of more general software (the ‘Semper’ system) in the new environment has been measured carefully, and found to be about 10 times its performance on our previous PDP 8/E computer; particular attention is given to the data management techniques crucial to the system's efficiency. Some current applications are illustrated, including high resolution image interpretation and image averaging of biological crystals.
A method for rapid in situ measurement of foil thickness in a TEM
Authors: Preez W. B. du , Kritzinger S. 
Published: August 2011

SUMMARYA method is described which can be used for rapid in situ determinations of relative foil thicknesses in a transmission electron microscope, and is illustrated for the case of aluminium. A calibration curve for the foil thickness determination was obtained by measuring the relative transmission of electrons through standard thickness foils which were prepared and measured outside the electron microscope. By using this calibration curve, it was merely necessary to measure the relative transmission of electrons through an unknown specimen in order to determine its thickness.
An intercellular network artefact in glycol methacrylate dehydrated neonatal cartilage
Authors: Shepard Nora , Mitchell Nelson , Harrod John 
Published: August 2011

SUMMARYA striking network thought to consist of glycosaminoglycan in neonatal cartilage has recently been reported following glycol methacrylate (GMA) dehydration and embedding. This study attempted to learn why the network was not seen in other preparations previously reported.Comparative light and transmission electron microscopy of the network structures was carried out to determine their biological significance. We have shown the networks to be reproducible artefact, attained only following GMA dehydration of glutaraldehyde fixed neonatal cartilage.
The histochemical basis of quantitative histology*
Authors: Stoward Peter J. , Ploem Johan S. 
Published: August 2011

SUMMARYThe interaction between histochemistry and microscopy for quantifying the morphology and function of cells in sections of tissue is reviewed.In principle, the morphological parameters of cells can be measured in suitably‐stained sections using image analysers. In practice, however, the individual cells often cannot be distinguished from each other in such systems. This problem might be overcome, at least in muscle, by visualizing types III and IV collagen in the connective tissue and basement membranes surrounding the cells.The functional capacities of cells within tissues can be inferred by measuring the activities of their key enzymes with quantitative histochemical techniques. At present, the wrong enzymes are frequently chosen for this purpose. Flux‐generating and physiologically significant enzymes are preferable, but this requires new histochemical techniques to be devised and validated quantitatively for use with the computer‐assisted analytical microscopes that are now becoming available commercially.
Electron microscopy of frozen water and aqueous solutions
Authors: Dubochet J. , Lepault J. , Freeman R. , Berriman J. A. , Homo J.‐C. 
Published: August 2011

SUMMARYThin layers of pure water or aqueous solutions are frozen in the vitreous state or with the water phase in the form of hexagonal or cubic crystals, either by using a spray‐freezing method or by spreading the liquid on alkylamine treated films. The specimens are observed in a conventional and in a scanning transmission electron microscope at temperatures down to 25 K. In general, the formation of crystals and segregation of solutes during freezing, devitrification and evaporation upon warming, take place as foreseen by previous X‐ray, thermal, optical and electron microscopical studies. Electron beam damage appears in three forms. The devitrification of vitreous ice. The slow loss of material for the specimen at a rate of about one molecule of pure water for every sixty electrons. The bubbling in solutions of organic material for doses in the range of thousands of e nm−2. We propose a possible model for the mechanism of beam damage in aqueous solutions.The structural and thermal properties of pure frozen water important for electron microscopy are summarized in an appendix.
Examination of whole cell mounts by transmission electron microscopy using cultures grown on carbon coated coverslips
Authors: Tolson Neil D. , Boothroyd Brian 
Published: August 2011

SUMMARYCultures of porcine granulosa cells have been grown on serum coated carbon films deposited on glass coverslips. Intact and detergent‐treated cultures were critical point dried, chromium shadowed and removed from the coverslips by dilute hydrofluoric acid. Whole cell mounts were examined by conventional transmission electron microscopy. The advantage of this system over other methods includes the ability to: (1) examine cells with a highly rounded morphology, (2) use high cell densities, (3) study cell projections extending onto the substratum, (4) maintain cultures for long periods, (5) examine large samples easily, and (6) readily use the same cultures for transmitted light and fluorescent microscopy, scanning and transmission electron microscopy (SEM and TEM).
Differential staining of polyanions according to critical electrolyte concentration principles in mixed solvents
Authors: Scott J. E. , Hughes E. W. 
Published: August 2011

SUMMARYThree types of cationic reagent—cellulosic anion exchangers, cationic phthalocyanin dyes and detergents—formed insoluble complexes with the polyanions heparin, chondroitin‐4‐sulphate, hyaluronate, alginate and DNA. Dissociation of their complexes by MgCl2 was a critical phenomenon, occurring at a sharply defined concentration, the critical electrolyte concentration (CEC), in water and in water‐organic‐solvent mixtures. CECs of polysulphates were always higher than those of polycarboxylates or polyphosphates, especially in the presence of dimethyl sulphoxide or ethanol. The latter effect should improve biochemical fractionations and differential histochemical staining of polyanions.A general theoretical framework is proposed. Complex formation is promoted by electrostatic attractions, and results in a loss of polymer mixing energy. Electrolytes suppress the electrostatic interaction, thus preventing complex formation. More efficient suppression of the electrostatic interaction is required in a ‘worsening’ solvent, i.e. where a rise in CEC occurs. Plots of CEC against solvent composition are interpreted on these bases. Available data on electrolyte solutions account for specific ionic effects.The dissociation of phthalocyanin dye micelles in aqueous dimethyl sulphoxide, etc, was studied spectroscopically. The results support and extend the conclusions derived from the insoluble anion‐exchange celluloses.The general concepts serve as a bridge between biochemical and histochemical fractionations (i.e. specific staining of substrates).
The STEM approach to the imaging of surfaces and small particles
Authors: Cowley J. M. 
Published: August 2011

SummaryThe characteristics of scanning transmission electron microsopy, which make it a particularly powerful tool for the study of surfaces and small crystals, include the serial nature of the image signal which makes it amenable to recording and image processing procedures, the possibility of correlating the image data with microdiffraction patterns and microanalysis of chosen small regions and the possibilities for combining several different image signals obtained simultaneously. Images obtained from surfaces using reflected diffraction beams may be very sensitive to variations of surface structure but the resolution, depth of focus and contrast of the images are strongly dependent on the nature of the surface and the aperture sizes used in the microsope. Microdiffraction patterns may be obtained from small surface features. Electron energy loss analyses of the diffracted beams provides sensitive indications on surface electron excitations. Microdiffraction patterns obtained in transmission from regions of 1–5 nm diameter provide valuable information on the structure and defects of small crystals, such as those of platinum and gold which are of interest in relation to the study of catalysts.
The high resolution electron microscopy of stacking defects in Cu–Zn–Al shape memory alloy
Authors: Cook J. M. , O'Keefe M. A. , Smith David J. , Stobbs W. M. 
Published: August 2011

SummaryThe characteristic defects in the martensitic phase of the memory alloy Cu–Zn–Al have been investigated using the Cambridge University 600 kV High Resolution Electron Microscope. Conditions are found under which the images can be quantitatively simulated when this involves the transfer of structural information at resolutions beyond the first zero of the contrast transfer function. Defects of sequence‐type were positively identified by the comparison of high‐resolution micrographs with full dynamical image simulations.
A transformation anomaly in a Cu–Zn–Al alloy
Authors: Stobbs W. M. 
Published: August 2011

SummaryA comparison is described of the structures of an M9R Cu–Zn–Al alloy as quenched directly into the martensitic state, and as stabilized, with the structure of the material after up‐quenching into the β1 state after which treatment the martensitic memory transformation occurs thermoelastically. Preliminary results on the increased tendency for the stabilized alloy to form f.c.c. stacking sequence regions are given and discussed.
The pore geometry and structure of the eggshell of the North Island brown kiwi, Apteryx australis mantelli
Authors: Silyn‐Roberts H. 
Published: August 2011

SUMMARYThe total effective pore area of the eggshell of the North Island brown kiwi has been quantified and found to be only 27% of that allometrically predicted. This has been achieved by a reduction in the number of pores to 53% of allometric prediction and of individual pore area to 66%. A new technique for pore‐casting has been devised using a low viscosity epoxy resin designed for crack‐filling in concrete. Polished and weakly etched sections of the central layer of the shell have revealed an arrangement of calcite previously believed to be unique to the tinamou.
Effects of glutaraldehyde and critical point drying on the shape and size of erythrocytes in isotonic and hypotonic media
Authors: Eskelinen Sinikka , Saukko Pekka 
Published: August 2011

SUMMARYScanning electron microscopy (SEM) was applied to studies on osmotically swollen erythrocytes fixed by a method using increasing concentrations of glutaraldehyde (GA), OsO4 as a post fixative, and critical point drying (CPD). This fixation method prevented the osmotic effect of GA itself and preserved the cellular equilibrium shape intact in various media, i.e. discocytes in an isotonic medium and ellipsoids or spheres and ghosts in a hypotonic medium. The discocytes were reduced less in diameter and area than the ellipsoids and spheres during CPD, but the degree of volume shrinkage was of the same magnitude (approx. 73%) regardless of the cell shape. The shrinkage of the discocytes was advanced until the dry volume (approx. 29 μm3) was reached, while the shrinkage of the osmotically swollen cells ceased earlier. A miniaturization process coupled with solvent evaporation is suggested as an explanation for this. The osmotic swelling of erythrocytes was studied quantitatively with the aid of SEM micrographs. The increase in volume was about 60%, which is in agreement with the values obtained by light microscopy for unfixed and GA‐fixed cells in the present work and with those reported in the literature.