bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Notes on the History of the STEM
Authors: Crewe Albert V. 
Published: June 2020

I have been asked to give a retrospective talk about the STEM, something which I find difficult to do since I have always preferred to look forward, not backward. I keep no diaries or chronology of successes and failures, and even have difficulty providing a publication list. For this reason I will apologize now for any errors or omissions in my account.In the space available here it is not possible to write down the history of the STEM and I can only provide a brief glimpse into the efforts of so many people but there are some salient points to be made.The ideas and concepts behind the STEM have their origins in nuclear and high energy physics where the language and terminology is often very different from that which is used in electron microscopy. One of my earliest mistakes was in not recognizing that fact and remaining insensitive to the language of microscopy for too long.
An Electron Histochemical and Ultrastructural Evaluation of Human Nasal Septal Cartilage Grafts Stored in Merthiolate® and Alcide®
Authors: Wasserman Arthur J. , Christiansen David L. , Kato Y. Pedro , Glasgold Alvin J. , Silver Frederick H. 
Published: June 2020

Cartilage is used widely in reconstructive surgery. The inaccessiblity of live cartilage homografts and the limited extended survival record of preserved cartilage used as grafts (1) during surgery creates a need to understand the factors related to post-operative graft resorbtion. Structural changes in chemically preserved human nasal septum (HNS) and a decrease in the lower stiffness (2) of these tissues suggest compositional changes. The purpose of this study was to assess the chronic affects of the chemical preservatives MerthiolateR and AlcideR on HNS using S.E.M., T.E.M. and the proteoglycan specific electron dense stain quinolinic blue (QB) (3).HNS removed during rhinoplasty or after storage at 4 ° C for 6 months in Mertiolate R or AlcideR were diced into 1 mm cubes while immersed in fixative. Either 1.5% glutaraldehyde-4% paraformaldehyde in 0.1 M cacodylate with 4 mM CaCl2, or 2.5% glutaraldehyde in a critical electrolyte solution of 25mM Na acetate-0.3 M MgCl2 with 0.05% QB were used.
Morphological Changes in Tissue-Cultured Cells Due to Variation in Growth Matrices
Authors: Hogan M. E. , DeGaetano D. H. , Klomparens K. L. 
Published: June 2020

As the use of isolated cell cultures increases as an experimental model, there has been a proportional increase in the number of matrices used for cell growth support. These matrices vary in shape, texture and porosity, and as a result, affect the cells grown on them.The ultrastructural characteristics of several of these growth matrices were examined using two cell types chosen for their distinct growth habits. Chinese Hamster Ovary cells and Balb 3T3 Mouse Fibroblasts were grown on flat substrates (glass, tissue culture plastic, Millipore filters) as well as spherical (glass, tissue culture plastic, cross-linked dextran) matrices. Cells were plated maintaining egual densities and growth surface area. Once the majority of the cells reached confluency (approx. one week), the cell morphology on each matrix was examined using scanning electron microscopy and digital analysis of cell attachment area.Variation in cell shape was dramatic between matrices, being most noticeable between a textured surface (filter, dextran bead), and that of a smooth (glass) surface (Figs. 1 and 2). Even within smooth surfaces, some variation was observed.
Neurofilaments Pack Differently in Different Parts of the Same Axon
Authors: Price R. L. , Lasek R. J. , Katz M. J. 
Published: June 2020

Quantifying cytological ultrastructure can reveal subtle but consistent differences in the organization of cytological elements, such as the cytoskeletal polymers. From these differences, it is possible to infer the dynamic mechanisms that contribute to those organizational variations which give cells their regional characteristics (Lasek, 1988). Myelinated axons manifest many regional specializations. Moreover, such axons have a repeating stereotyped pattern of interactions with the numerous Schwann cells that are distributed along their lengths. Within this pattern, certain regional specializations occur repeatedly: nodes of Ranvier, internodal regions with compact simple myelin, and Schmidt-Lanterman (S-L) clefts (i.e., internodal regions where the Schwann cell cytoplasm separates the myelin lamellae). We have quantified neurofilament number and density in these different regions of the axon in order to explore the mechanisms that underlie neuronal shape.Twenty-eight day old chickens were perfused by cardiac puncture with 3-4 1 of fixative (4% paraformaldehyde, 2% glutaraldehyde, 0.005% CaCl2, in 0.1M cacodylate buffer, pH7.4). The somatic motor branch of the oculomotor nerve was removed and fixed overnight at 4°C, followed by a buffer rinse and lh in 1% OsO4in 0.1M cacodylate at room temperature.
Preliminary investigation of fiber ultrastructure after enzymatic digestion
Authors: Woodward Janet H. , Akin D. E. , Barton F. E. 
Published: June 2020

Knowledge on the chemical and physical structure of fiber is essential in determining forage quality. Current methods provide empirical results on fiber using chemical extractants. This paper is a preliminary report on methods to redefine fiber based on physiological (biochemical) procedures. TEM was employed to evaluate the relationship of fiber with specific enzymatic treatments.A modified AOAC Total Dietary Fiber Determination was used to prepare one group of insoluble fibers from two legumes of different nutritional quality. Three millimeter wedged-shaped leaflet sections of alfalfa (Medicago sativa L.) and 1-76 lespedeza [Sericea cuneata (Dumont)] were incubated stepwise with: (1) heat stable α amylase, pH 6.0, for h at 100°C; (2) protease, pH 7.5, for h at 60°C; and (3) amyloglucosidase, pH 4.5, for h at 60°C. All leaflet sections were retrieved and incubated for 24 h at 37°C with either: (1) 1% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0; (2) 10% (w/v) hemicellulase in 0.05 M acetate buffer, pH 5.5; or (3) 1% cellulase and 10% hemicel1ulase in the acetate buffer.
Dimethyl sulfoxide protection of endotoxin-induced myocardial injury
Authors: Stiers David L. , Brackett Daniel J. , Wilson Michael F. 
Published: June 2020

Within the framework of a multi-discipline project, myocardial structure was evaluated utilizing transmission electron microscopy (TEM) to access cellular integrity of the myocardium during endotoxemia. Our initial purpose was to evaluate the early progression of myocardial damage during development of endotoxemia in the conscious, instrumented rat. Since neutrophil activation and/or hypoperfusion resulting in ischemia are potential sources of excess free radical generation which may be the mechanisms for tissue injury during endotoxemia, we also examined the prgtfplive effects of dimethyl sulfoxide (DMSO) on myocardial ultrastructure.After instrumentation and endotoxin challenge (LD9024 hours), animals were perfused at one, two, or four hours with Karnousky's fixative, and hearts were removed for processing for TEM. The effect of DMSO (6 mg/kg) on the development of endotoxemia was evaluated by intraperitoneal administration 20 min prior to endotoxin challenge. These animals presented typical cardiac, metabolic, and circulatory responses to endotoxin challenge indicative of ultimate lethality.
Ultrastructure of myoepithelial cell in parotid gland
Authors: Sun C. N. 
Published: June 2020

Myoepithelial cells have been observed in the prostate, harderian, apocrine, exocrine sweat and mammary glands. Such cells and their numerous branching processes form basket-like structures around the glandular acini. Their shapes are quite different from structures seen either in spindleshaped smooth muscle cells or skeletal muscle cells. These myoepithelial cells lie on the epithelial side of the basement membrane in the glands. This presentation describes the ultrastructure of such myoepithelial cells which have been found also in the parotid gland carcinoma from a 45-year old patient.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4 percent glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate. Ultrastructurally, the pattern of each individual cell showed wide variations.
Fate of thickened perineurial cell basement membrane in a diabetic patient following pancreas transplantation
Authors: Beggs J. L. , Johnson P. C. , Watkins C. J. , Olafsen A. G. , Jones C. P. , Targovnik J. 
Published: June 2020

The perineurial sheath of dermal nerves is usually composed of one to several cell layers. Thickening of perineurial cell basement membranes (PCBM) is a common feature in diabetics. Since PCBM thickening may have relevance to the cause of diabetic neuropathy the fate of thickened PCBM following various treatment regimens is of prime importance. In this study, we examined dermal nerves of monozygotic twins discordant for diabetes to determine the effects of pancreas transplantation on PCBM thickness.Patient History and Methods: This 53 year old diabetic man with an 18 year history of insulin dependency presented with progressive development of retinopathy, nephropathy and neuropathy. Pancreas transplantation (donor Identical twin) was performed to treat diabetic complications. Shortly after transplantation, the patient became normoglycemic and has remained euglycemic for 2 years. Signs and symptoms of diabetic complications improved; nerve conductance in the lower extremities improved. Abdominal skin biopsies were taken from the twins before transplantation and subsequent biopsies (1,2 yr post-transplant) were taken from the diabetic patient.
Permeability of the microcirculation in area postrema of rat
Authors: Ghoneim Shams M. , Faraci Frank M. , Baumbach Gary L. 
Published: June 2020

The area postrema is a circumventricular organ in the brain stem and is one of the regions in the brain that lacks a fully functional blood-brain barrier. Recently, we found that disruption of the microcirculation during acute hypertension is greater in area postrema than in the adjacent brain stem. In contrast, hyperosmolar disruption of the microcirculation is greater in brain stem. The objective of this study was to compare ultrastructural characteristics of the microcirculation in area postrema and adjacent brain stem.We studied 5 Sprague-Dawley rats. Horseradish peroxidase was injected intravenously and allowed to circulate for 1, 5 or 15 minutes. Following perfusion of the upper body with 2.25% glutaraldehyde in 0.1 M sodium cacodylate, the brain stem was removed, embedded in agar, and chopped into 50-70 μm sections with a TC-Sorvall tissue chopper. Sections of brain stem were incubated for 1 hour in a solution of 3,3' diaminobenzidine tetrahydrochloride (0.05%) in 0.05M Tris buffer with 1% H2O2.
Effects of carbamylcholine on chick embryo aggregate retina cell cultures
Authors: Cohen Glenn M. , Ray Radharaman 
Published: June 2020

Retinal,cell aggregates develop in culture in a pattern similar to the in ovo retina, forming neurites first and then synapses. In the present study, we continuously exposed chick retinal cell aggregates to a high concentration (1 mM) of carbamylcholine (carbachol), an acetylcholine (ACh) analog that resists hydrolysis by acetylcholinesterase (AChE). This situation is similar to organophosphorus anticholinesterase poisoning in which the ACh level is elevated at synaptic junctions due to inhibition of AChE, Our objective was to determine whether continuous carbachol exposure either damaged cholino- ceptive neurites, cell bodies, and synaptic elements of the aggregates or influenced (hastened or retarded) their development.The retinal tissue was isolated aseptically from 11 day embryonic White Leghorn chicks and then enzymatically (trypsin) and mechanically (trituration) dissociated into single cells. After washing the cells by repeated suspension and low (about 200 x G) centrifugation twice, aggregate cell cultures (about l0 cells/culture) were initiated in 1.5 ml medium (BME, GIBCO) in 35 mm sterile culture dishes and maintained as experimental (containing 10-3 M carbachol) and control specimens.
Light and electron microscopic investigation of adenohypophyses of germfree, food-restricted, and germfree-food restricted aging, male lobund-wistar rats
Authors: Ilse G. , Kovacs K. , Ryan N. , Sano T. , Stefaneanu L. , Asa S.L. , Snyder D. 
Published: June 2020

Germfree state and food restriction have been shown to increase life span and delay tumor occurrence in rats. We report here the histologic, immunocytochemical and electron microscopic findings of adenohypophyses of aging, male Lobund-Wistar rats raised at Lobund Laboratories. In our previous study, the morphologic changes in the adenohypophyses of old rats have been extensively investigated by histology, immunocytochemistry and electron microscopy. Lactotroph adenomas were frequent in Long-Evans and Sprague-Dawley rats, whereas gonadotroph adenomas were frequent in Sprague-Dawley and Wistar rats.Male Lobund-Wistar rats were divided into four groups: 1) conventional, which were raised under normal non-germfree environment and received food ad libitum; 2) germfree-food ad libitum; 3) conventional environment-food restricted and 4) germfree-food restricted. The adenohypophyses were removed from 6-month-, 18-month- and 30-month-old rats. For light microscopy, adenohypophyses were fixed in formalin and embedded in paraffin.
Hypoxia-induced structural changes in cultured heart cells
Authors: Hawkey L.A. , LeFurgey A. , Wagenknecht B. , Lieberman M. 
Published: June 2020

Understanding the mechanisms involved in irreversible cell injury during myocardial ischema is an important step in developing treatments to lessen or prevent damage at the cellular level and /or to speed cell recovery. Establishing the sequence of changes that occur, both ultrastructurally and biochemically, when heart cells suffer oxygen deprivation is necessary in order to reach this understanding. The objective in the current studies is to document the relationships between, and the time dependence of, morphological, ionic and metabolic alterations occurring when cultured heart cells are exposed to hypoxia and substrate depletion.Embryonic chick myocardial cells were grown as muscle-enriched monolayer cultures for four days. Non-muscle cell cultures were prepared and grown as described previously, for evaluation of the response to hypoxia of the fibroblast component (<10%) of the muscle-enriched cultures. Cultures were then incubated in substrate-free media in an anaerobic chamber (PO2<0.1%) and samples were taken at one hour intervals for biochemical and ultrastructural analyses.
Diagnostic virology in veterinary pathology: techniques for negative staining
Authors: Basgall Edward J. , Scherba Gail , Gelberg Howard B. 
Published: June 2020

Negative staining of virus suspensions is the quickest, easiest diagnostic technique currently available to the electron microscopist. Virus sampling and staining from directly collected fluids is inherently rapid, simple, and straightforward. Virions in a sample can be stained directly on a formvar coated grid then examined in a transmission electron microscope (TEM).The collection, detection, and identification of enteric viruses is more involved. Intestinal contents are often presented in a variety of states, from clear fluid to solid. In a diagnostic setting, a routinely reliable protocol is a necessity for fast, accurate results. Several authors have recommended various techniques for clarifying virus preparations from fecal samples. However, these methods do not inactivate pathogens in the samples. Moreover, a recent report indicates that technical staining parameters of virus staining could influence virus particle integrity. The routine use of 10% neutral buffered formalin (NBF) fixation prior to concentrating and staining virus samples both stabilizes and inactivates the majority of viruses encountered in a diagnostic setting.
Ultrastructural localization of carbohydrate determinants of lipopolysaccharide of coxiella burnetii (Phase I) by monoclonal antibodies
Authors: Mccaul T. F. , Williams J. C. 
Published: June 2020

Coxiella burnetii, the etiological agent of Q fever, is an obligate phagolysosomal bacterium and an unorthodox spore former. Morphologically distinct cell types, produced by a developmental cycle, are defined as large cell (LCV) and small cell variants (SCV). Recent study has shown phase I lipopolysaccharide (LPS-I) is differentially expressed among the cell variants. This antigenic variation was investigated further by use of a series of monoclonal antibodies (MAbs), directed against LPS-I, and post-embedding immunolabelling techniques. Since these MAbs recognize carbohydrate determinants of LPS-I, the specificity of the labelling was tested by carbohydrate reducing and oxidizing reagents prior to labelling.C. burnetii (9MIC7 strain), which was purified from infected yolk sac material of hen eggs by Renografin gradient centrifugation, was fixed for 3 h in 1.5% glutaraldehyde and 0.2% picric acid in 66mM Na-cacodylate buffer, pH = 6.8; pre-embedded in 2% Difco Nobel agar; and then rinsed once (15 min) in the same buffer.
Scanning electron microscopy of pneumocoptes penrosei (Weidman) from the black-tailed prairie dog, Cynomys ludovicianus
Authors: Nunamaker C.E. , Williams E.S. , Sherman S.L. 
Published: June 2020

Pneumocoptes penrosei (Weidman 1917) is a parasitic mite that infests the lungs of the prairie dog, Cynomys ludovicianus. Taxonomic characterization of these mites has been previously described using light microscopy, however, scanning electron microscopy (SEM) provides a more detailed view of these arthropods.In December, 1987, a black-tailed prairie dog was submitted to the Wyoming State Veterinary Laboratory, Laramie, WY. The prairie dog had been in captivity for several years and had recently lost weight. No lesions were observed on gross examination. The lung was normal on light microscopic examination, however, numerous cross sections of mites were observed within the alveoli. Samples of the mite infested tissue were prepared for scanning electron microscopy. One group of formalin-fixed lung tissue was digested in acid pepsin at 37°C in a shaker waterbath for 12 hours. The mites were removed from the digested tissue, transferred into phosphate buffer, and centrifuged at 1500 rpm for two minutes prior to post-fixation in 1% OSO4 on ice for 30 minutes.
The homogeneity and radiation sensitivity of a calcium-containing low-viscosity resin for use as a standard in analytical electron microscopy
Authors: Armstrong David A. 
Published: June 2020

The availability of good elemental standards is essential for the quantitative analysis of soft biological tissues. A standard that contains a homogeneous distribution of the elements of interest, has a high level of stability in the electron beam, and models the specimen in chemical composition would be an ideal case. We are involved in a continuing investigation examining both the homogeneity and the radiation sensitivity of a set of prepared standards. Here we report the initial results, with regard to calcium distribution within, and radiation sensitivity of, a calcium containing low viscosity epoxy resin.Calcium Naphthenate was incorporated into Spurr's resin using a protocol given by Simon (personal communication), from concentrations of 30 millimoles of calcium per kilogram of resin to l00mm/kg of resin.
The maximum-likelihood method for em autoradiography: Small-system implementation technique
Authors: Roysam Badrinath 
Published: June 2020

Electron Microscopic Autoradiography (EMA) is of growing importance as a technique for the quantification of radiolabelled biochemicals in subcellular structures. The Maximum-Likelihood (ML) method of Miller et al. has been shown to be substantially superior to the conventional crossfire (OF) method. In this paper, we present a method for reducing the computational requirements of the ML method to a point where it becomes feasible to implement it on a small computer. We then describe EMA/PC, which is a device-independent computer program that implements the complete ML method on the IBM-PC class of machines.We have shown that the iterative Expectation-Maximization (EM) algorithm has a high computational complexity which can be reduced dramatically via a problem reformulation which involves the computation and use of sufficient statistics, which we call Grain-Organelle Probabilities (GOPs). The computation of GOPs requires the integration of a two-dimensional point-spread function over regions defining subcellular structures in the given set of electron micrographs.
Atom-probe microscopy
Authors: Kellogg G. L. 
Published: June 2020

The atom-probe field ion microscope is a highly-sensitive, time-of-flight mass spectrometer which is used to identify individual atoms or groups of atoms that appear in a field ion microscope image. Under ideal conditions the atom-probe can yield the surface and bulk composition of a solid sample with true atomic spatial and depth resolution. Since its development in the late 1960's, the atom-probe has been used to study a variety of problems in the areas of metallurgy, surface science, and materials science. This review focuses on operational principles of the atom-probe and selected applications carried out in the author's laboratory.The most widely-used atom-probe follows the original design developed by Müller, Panitz and McLane. In this instrument a small probe-hole is placed in the viewing screen of a field ion microscope. The image is adjusted such that the atom or atoms of interest are in alignment with the probe hole.
A study of small probe formation in a field emission gun TEM/STEM
Authors: Veiss J. K. , Carpenter R. W. 
Published: June 2020

A Philips EM 400T equipped with a field emission gun (FEG) has been studied to determine the spatial and angular current distribution in the electron microprobe at the specimen level. The field emission gun provides a high brightness source capable of producing electron probes with diameters of several nanometers and total currents of 0.05 - 50 nA. The advantage of the TEM/STEM over the dedicated STEM in this study is its ability to produce real-space images of the probe at the specimen plane. Detailed information about the probe current distribution can be experimentally obtained and applied to various small-probe techniques (i.e. HRAEM, STEM, microdiffraction) in order to determine their spatial resolution.The probe diameters listed in Table 1 were measured from high magnification images of the focussed probes which showed sharply defined outlines of the aberration figures. Additional measurements were obtained by scanning the probe across a small fixed entrance aperture to an EELS spectrometer, and also by an edge resolution method similar to that used by Venables and Janssen.