bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and elemental characterization of heart cells grown in a collagen matrix
Authors: LeFurgey A. , Hawkey L.A. , Carney M.C. , Ingram P. , Lieberman M. 
Published: June 2020

Cultured embryonic chick heart cells have been utilized as a model system for characterization of various membrane transport mechanisms. One advantage of this system is that the cells may be grown with differing geometries to minimize diffusion limitations and to optimize the growth configuration for particular techniques, such as ion-selective microelectrode measurements, fluorescent dye indicators, patch clamp, etc. A spontaneously contracting strand of cells embedded in a collagen matrix has recently been developed for measurements of cytoplasmic free ions by nuclear magnetic resonance (NMR) spectroscopy. These same strands, which provide the large numbers of cells needed for NMR, can be subdivided into small fragments ideal for cryopreservation prior to electron probe X-ray microanalysis (EPXMA). The aims in this study were to characterize the ultrastructure of cardiac cells within the strand, to demonstrate the quality of preservation obtainable by quick freezing methods, and to quantitatively map with EPXMA the distribution of physiologically relevant elements in thin, freeze-dried cryosections of the cells.Cells were isolated by serial trypsinization of 11-day old embryonic chick hearts. Strands of cells approximately 100 cm in length and 0.2 mm in diameter were obtained by extrusion of a cell-collagen mixture through polyethylene tubing into media within a culture dish. Three to five millimeter segments of 1-day old strands which contracted spontaneously were preserved by rapid immersion in liquid nitrogen-cooled liquid propane at 〜-185°C and stored in liquid nitrogen prior to being (a) cryosectioned for subsequent EPXMA or (b) freeze-substituted for conventional transmission electron microscopy (CTEM). Segments of strands were also chemically preserved in 2.5% glutaraldehyde in 0.1 M sodium cacodylate and processed as above for comparative CTEM. Cryosections of the frozen strands were cut at <-140°C with a dry glass knife and placed directly onto pre-cooled, carbon-coated, 200 mesh, fine bar nickel grids with a precooled implement. The grids were transferred to a liquid nitrogen cooled copper well for freeze drying at 10‒3 Torr over 24 to 48 hours. Prior to EPXMA, the grids were coated with 〜1OOÅ carbon.
Patterns of mucilage production and secretion in pennate diatoms
Authors: Sicko-Goad L. , Kociolek J. P , Stoermer E. F. 
Published: June 2020

Although mucilage production is ubiquitous among diatoms, there have been few studies documenting its production and secretion. Several studies have identified a regular arrangement of Golgi, endoplamic reticulum, and mitochondria as being responsible for mucilage production in centric diatoms. However, such an arrangraent has not been identified for pennate diatoms, although fibrillar vesicles have been described in the vicinity of Golgi and mitochondria and are believed to be involved in mucilage production. The production and secretion of mucilage in certain taxa of pennate diatoms is especially important because it provides various types of growth forms including stalks, tubes and encapsulated cells. The following report compares ultrastructural differences among araphid, monoraphid and biraphid diatoms.Collections of mucilage-producing diatoms exhibiting different growth forms were taken from rocks along the shores of Lakes Michigan and Superior. Samples were field-fixed in 1% paraformaldehyde-glutaraldehyde in cacodylate buffer and stored on ice until samples were returned to the lab. Samples were then postfixed in 1% OsO4, dehydrated in a graded ethanol-propylene oxide series, embedded in Embed 812 and sectioned with a diamond knife. Sections were collected on cleaned formvar- coated 100 mesh copper grids and examined with a Philips 400 TEM.
Two structural states of the Z-band in cardiac and skeletal muscle
Authors: Schroeter J.P. , Goldstein M.A. , Bretaudiere J.P. , Michael L.H. , Sass R.L. 
Published: June 2020

We have recently established the existence of two structural states of the Z band lattice in cross section in cardiac as well as in skeletal muscle. The two structural states are related to the contractile state of the muscle. In skeletal muscle at rest, the Z band is in the small square (ss) lattice form, but tetanized muscle exhibits the basket weave (bw) form. In contrast, unstimu- lated cardiac muscle exhibits the bw form, but cardiac muscles exposed to EGTA show the ss form.We have used two-dimensional computer enhancement techniques on digitized electron micrographs to compare each lattice form as it appears in both cardiac and skeletal muscle. Both real space averaging and fourier filtering methods were used. Enhanced images were displayed as grey-scale projections, as contour maps, and in false color.There is only a slight difference between the lattices produced by the two different enhancement techniques. Thus the information presented in these images is not likely to be an artifact of the enhancement algorithm.
Transmission and Scanning Electron Microscopic studies of ocular leprosy in nine-banded armadillos
Authors: Malaty R. , Pedroza L. , Beuerman R.W. 
Published: June 2020

Leprosy is one of the leading causes of preventable blindness in the world, yet It is largely ignored in blindness prevention programs. To date, little is known about the pathogenesis of ocular leprosy in humans. Histopathological studies have been necessarily 1imited to eyes removed at autopsy or enucleated from patients with advanced lepromatous leprosy. In an attempt to define the pathogenesis of the ocular complications of leprosy, we have studied the eyes of animal models namely, nine-banded armadillos with 1epromatous leprosy and injectedMycobacterium leprae(M. leprae) directly in the corneal stroma of armadillos.Fifty armadillos with experimental or naturally-acquired lepromatous leprosy were studied. Six armadillos were injected in the corneal stroma with 1 ul of anM. lepraesuspension and examined two and four months later. Both eyes of each animal were enucleated at autopsy, fixed in paraformaldehyde-glutaraldehyde and processed for light and electron microscopy (EM). For light microscopy, the eyes were embedded in plastic methacrylate and sections stained with a modified acid-fast stain. For EM, tissues were post fixed in 1% OsO4dehydrated, and embedded in epon.
Ultrastrctural identification of viral infections in paraffin sections stained by immunohistochemistry and in situ hybridization
Authors: Chien K. , Shintaku I.P. , Wu G.D. , Van de Velde R.L. , Heusser R. , Danao F. , Geller S.A. 
Published: June 2020

Confirmation of viral infections in surgical biopsies is sometimes limited to routine paraffin sections because a specimen may not have been set aside for culture or culture results are negative. Since viral infections are frequently focal and localized to only a few cells, definitive histopathological diagnosis can be difficult to achieve even with immunohistoGhemistry (IHC), in situ hybridization (ISH) or electron microscopy. In this paper, we would like to demonstrate a siirple and direct approach to confirming viral infections in paraffin sections , using two immuno-labelling techniques coupled with electron microscopy.Paraffin sections of surgical specimens are deparaffinized in xylene and rehydrated through graded ethyl alcohol. Herpes simplex virus (Figure 1) and Toxoplasma gondii are localized immunohistochemically by the peroxidase antiperoxidase technique and Pneumocystis carinii (Figure 2) by 3 step ipdirect method, using 3,3'-diaminobenzidine tetrahydrochloride as the chrmogen, CMV ENA probe (ENZO Biochemicals) is used for in situ hybridization, following kit instructions (Figure 3 & 4). After the final chromogen reaction, wet sections are examined with a light microscope. Slides in vrfiich focal positive staining is difficult to interpret as specific are fixed in osmium tetroxide, dehydrated with graded acetone, and infiltrated with Poly/Bed 812. After polymerization, the epoxy blocks containing area of interest can be easily separated from the glass slides by heating on a 100 C hotplate for approximately 20 seconds . The area of interest should be positioned in the center of the block face for ultrathin sectioning. With careful adjustments of knife and microtcme, the area of interest can be precisely sectioned without loss of tissue. Ultrathin sections are collected on uncoated mesh grids for higher contrast and then directly examined by TEM. Peroxidase-labelled microorganisms or viral DHA can be easily localized and identified without heavy metal staining. Cellular details can be further increased by staining with uranyl acetate and lead citrate. Tissue remaining in block face after sectioning is available for IM comparison with the EM micrographs.
Ultrastructural localization of acid phosphatase in lactating rat mammary gland
Authors: Farrell Harold M. , Maleeff Beverly E. , Wickham Edward D. , Leung Cecilia T. 
Published: June 2020

Acid phosphatases occur in a variety of mammalian tissues. Generally these enzymes can be divided into degradative enzymes (lysosomal) which are tartrate inhibited and general acid phosphatases which are not tartrate sensitive. The metabolic function of the latter class of enzymes is uncertain, but many phosphatases reverse the regulatory phosphorylation of enzymes, carried out by specific protein kinases. Mammary tissue actively accumulates casein, calcium and inorganic phosphate in secretory vesicles; these components subsequently condense into the colloidal complexes (casein mice lies) found in skim milk. In addition, tartrate insensitive acid phosphatases are found in mammary secretory tissue and in milk We therefore investigated the cytochemical distribution of mammary acid phosphatase to determine if any activity is associated with the endomembrane system responsible for the secretion of casein micelles.Tissue from lactating female Sprague-Dawley rats, 8-10 days postpartum, was excised
in blocks of 3 to 5 mm, immediately placed in ice-cold fixative (2% formaldehyde,0.25% glutaraldehyde in 0.lM cacodylate buffer, pH 7.4) , and minced with a razor blade. After fixation for 15 minutes, the finely minced tissue was transferred to 0.lM cacodylate buffer containing 8% sucrose (w/v) and 10% (v/v) dimethyl sulfoxide (DMSO) and kept overnight at 40°C.
Electron Microscopy as an aid to diagnosis in pediatric hematology/oncology
Authors: Saving K. L. , Caughey R. C. 
Published: June 2020

This presentation is designed to demonstrate how scanning and transmission electron microscopy techniques can be utilized to confirm or support a variety of unusual pediatric hematologic/oncologic disorders. Patients with the following diagnoses will be presented: (1) hereditary pyropoikilocytosis, (2) familial erythrophagocytic lymphohistiocytosis, (3) acute megakaryoblastic leukemia, and (4) pseudo-von Willebrand’s disease.All transmission and scanning electron microscopy samples were fixed in 2.5% glutaraldehyde, rinsed in Millonig’s phosphate buffer, and post-fixed with 1% osmium tetroxide. The transmission samples were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole ’ s non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin. Ultramicrotomy thin sections were stained with uranyl acetate and lead citrate and scanned using a JEOL-JEM 100C, The scanning samples were dehydrated with graded series of ethanols, critical point dried with CO2, gold-coated, and scanned using a JEOL-JSM 35. The peroxidase samples were fixed in 3% glutaraldehyde, incubated in diaminobenzidine (DAB), dehydrated with ethanol, embedded with Epon 812, and scanned without post-staining using a JEOL-JEM 100C.
Ultrastructural study of pulmonary endothelium in mouse model of the IL-2-induced vascuiar leak syndrome
Authors: Valentine T. M. , Anderson T. D. 
Published: June 2020

Interleukin-2 is being evaluated in cancer immunotherapy in people. rIL-2 is associated with vascular leak syndrome (VLS) characterized by peripheral edema, ascites and pulmonary edema. The histopathologic changes associated with rIL-2 administration have been described in mouse models, however, the ultrastructural changes in VLS are undefined. In these studies we have utilized a mouse model of VLS to characterize the pulmonary ultrastructural changes which are associated with pulmonary edema.B6D2F1 (BDF) mice, (3M/3F/groups) from Charles River Lab., New York, were treated intraperitoneally for five days with vehicle for rIL-2 or with 30,000 U/gm rIL-2, BID as previously described. At necropsy, lungs were fixed by intratracheally at perfusion pressure of 30cm of H2O with modified Karnovskys fixative diluted with 0.2M sodium caccdylate buffer, ph7.4, for 24 hours. Transverse sections of the left lung (1mm thick) were post-fixed in osmium tetroxide (2hrs) and processed for electron microscopy. Ultrathin sections were stained with uranyl acetate and lead citrate and examined in a Philips 300 electron microscope.
Positive stain for light and electron microscopic demonstration of spirochetes in subgingival plaque and crevicular fluid samples from periodontal diseased sites
Authors: Giammara B. , Burkes E.J. , Scruggs R. , Greco G. , Yates P. , Hanker J. 
Published: June 2020

In a recent study of 400 subgingival plaque samples from over 110 adult periodontitis patients, spirochetes were the overwhelming microbial type, averaging about 45% of the microbial count. This finding supports earlier arguments that spirochetes are pathognomonic in periodontal disease. Other studies had shown clear-cut differences in the microbial composition of healthy and diseased subgingival sites — the proportion of spirochetes being significantly higher in the latter. Another study indicated that periodontal deterioration at these sites could be predicted better by increased proportions of motile rods and spirochetes than by clinical measurements. However, spirochetes of all sizes and species do not show the same degree of association with periodontal breakdown. Moreover, spirochetes are usually difficult to culture and stain; they are generally monitored by darkfield or phase contrast microscopy.The PATS reaction, a modified periodic acid-Schiff(PAS) reaction which deposits silver for light and electron microscopy appears to stain Gram(-) bacteria positively as well as neutrophils and activated macrophages. When studying the stained Gram(-) bacteria on coverslip smears of subgingival plaque or crevicular fluid samples of patients by light microscopy, varying numbers of intensely stained spirochetes of different sizes were observed (Figs. 1,2). More spirochetes were usually seen in samples from diseased sites. After drying replicate PATS-stained coverslips with hexamethyldisilazane they were sputter coated with gold, and. then examined by the SEI and BEI modes of scanning electron microscopy (Figs. 3-6). A permanent record of the proportions of large, medium and small spirochetes at each site could thus be obtained. Generally, greater numbers of gram negative bacteria including some spirochetes were stained in samples from diseased sites. At some sites, however, spirochetes were the predominant microbes in both crevicular fluid and subgingival plaque (Fig. 1).
Ultrastructural & image analysis of mitochondrial changes in myocardium of copper-deficient rats administered a toxic dose of cocaine
Authors: Bielenberg U. , Burns W. , Smith J.C. 
Published: June 2020

We examined the effects of a single dose of cocaine (Coc) on the myocardium of rats fed copper sufficient (CuS) compared to copper deficient (CuD) diets. Weanling males were fed either CuS (n=13) or CuD (n=12) for 7 weeks. Ten in each group, (paired for Cu status), were injected (ip) with Coc-HCL (80-90mg/kg bw), 5 served as controlsRats which survived for 15 minutes were killed and heart tissue was obtained for light and transmission electron microscopy as well as Cu analysis. Tissue for ultrastruetural study was fixed in Carson’s fixative and post fixed in osmium tetroxide.Myocardial foci showed necrosis, fibrosis, and inflammation in all rats given cocaine but were more severe in the CuD group. CuS controls (no Coc) showed no similar lesions. Ultrastructurally the
myocardium confirmed the light microscopy findings and showed apparent increase in the number of mitochondria which were of variable sizes and shapes. Giant mitochondria, clumping and foci of
molding were observed. Crystalline configurations of cristae were also seen.
Ultrastructural effects of exogenous hydrogen peroxide on the myocardium
Authors: Oguro T. , Aida K. , Onodera T. , Ashraf M. 
Published: June 2020

It has been suggested that hydrogen peroxide (H2O2) is indirectly associated with postischemic-reperfusion injury of the heart. Previously, we reported that the heart was not damaged when perfused with exogenously generated superoxide anions. However, H2O2, a dismutation product of superoxide anion severely affected the heart structure and function. In this study, we evaluated the ultrastructural changes of the cel1 membranes in isolated rat hearts and cultured myocytes follow-ing treatment with exogenous H2O2.In the isolated hearts, 300 μM of H2O2, a concentration which was based on our earlier study was perfused for 5 minutes. For the last 2 minutes, 100 mg (2200 U/mg) of horseradish peroxidase was perfused to see the permeability of the cell membranes. In the isolated cultured myocytes, 300 μM of H2O2 was added to the medium for 30 minutes. Both the hearts and the isolated myocytes were fixed with 2.5% buffered glutaraldehyde, postfixed with 1% osmium tetroxide and were processed for electron microscopy.
Pt/Ir/C, a new, powerful coating material for High-Resolution SEM
Authors: Wepf Roger , Gross Heinz 
Published: June 2020

In-lens field emission SEM allows to image specimen surfaces with subnanometer resolution by collecting type I secondary electrons, with an incident electron probe size of abut 0.5 nm in diameter. To achieve such high topographic resolution on biological specimens adequate structural preservation and high resolving thin continuous coating films are necessary.Careful freeze-drying (“maintaining hydration shells”) followed by heavy metal shadowing at -250°C under ultra high vacuum conditions (UHV) allows to extract surface features ≤2 nm with TEM. TEM-shadowing films (Pt/C, Ta/W) are stabilized with a C-backing layer. Such a C-coat would blurr fine details when investigated with the SEM.At the right composition (C-content 25-40%, metal content 75-60%) only about 1.5 nm thick Pt/Ir/C-films remain three-dimensionally stable when transferred to atmospheric conditions after freeze-drying samples with macromolecular dimensions. Pt/Ir/C is made by evaporating a Pt/Ir cylinder (diameter 1.5 mm, 70% Ir) inserted into a graphite rod (diameter 2 mm).
Sperm associations in rat epididymis
Authors: Fomés Miguel W. , Burgos Mario H. 
Published: June 2020

During epididymal transit a head to head association of spermatozoa has been described in guinea pig, Loris and marsupials. In guinea pig they are permanent and androgen dependent. Other type of sperm association described in nonseasonal. mammals, adopt the stiape of dense masses of degenerating spermatozoa.In the present study a new transitory head to head association in rat spemiatozoa is described which appears at the end of the epididymal transit and dense masses of associated spennatozoa in degeneration similar to those described in the literature. The sperm samples were obtained by puncture of the 3 main epididymal regions. The emerging fluid drops were immediately suspended in a balanced salt solution, placed in a slide-cover slide chanber at 36°C, and observed and recorded with a video equipment. Other drops of epididymal fluid were fixed in Mollenhauer (1976) and processed for light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Distribution of lectin binding sties and anionic sites in the rat zona pellucida
Authors: Skutelsky E. , Maymon R. , Bar-Shira (Maymon) B. , Shalgi R. 
Published: June 2020

The zona pellucida (ZP) in mammals is an extracellular coat which surroudns the oocyte during growth, fertilization and early development, consisting of a limited number of glycoproteins. Carbohydrates residues and charge properties of the ZP are believed to have a role in sperm-egg interaction. The purpose of the present study was to furtehr characterize the specific nature and distribution of the carbohydrate residues of the ZP and cumulus cells and anionic residues at the ultrastructural level.We used lectins as probes for specific sugar residues and polycationic colloidal gold (PCG) as a marker for aninonic sites. Immature female rats were induced to superovate. Ovulated, cumulus-oocyte complexes were isolated and fixed with 2.5% Glutaraldehyde, dehydrated and embedded in Araldite or LR-Gold. For light microscopic (LM) histochemistry, 0.5 μm sections were cut, deresined by Na-methoxide and labeled with biotin-derivatized lectins as probes and avidin biotin-peroxidase complex as visualant.
Correlation between blood-testis barrier development and onset of the first spermatogenic wave in normal and busulfan-treated rats
Authors: Cavicchia Juan C. , Sacerdote Fabio L. 
Published: June 2020

Pregnant rats (day 13) received 10mg/kg of Busulfan i.p. in order to deplete of germ cell the testes of the new born rats. The seminiferous tubules of their off spring from postnatal age 1 day up to day 35 were examined with TEM after fixation plus intercellular tracers, and with freeze-fracture techniques. During this period, the inter-Sertoli tight junctions of controls increase both in numbers and in length. Between days 10 and 13 the seminiferous cords have numerous preleptotene and leptotene spermatocytes (Fig.1) surrounded by tracer. The inter-Sertoli junctions are tortuous and predominantly perpendicular to the basal lamina. Between ages 13 and 20 days the seminiferous epithelium reaches zygotene-pachytene stages (fig.2) identified by the presence of synaptonemal complexes. The tracer is stopped at the inter-Sertoli junctions at this stage, whereas it still permeates tubules displaying preleptotene and leptotene spermatocytes.Freeze-fracture shows that the orientation of inter-Sertoli junctions has changed to parallel, both to each other and to the basal lamina (fig.3). In the Busulfan treated rats, the tubules continue having, up to postnatal day 30, only Sertoli cells and scanty spermatogonia.
TEM and SEM evidence for the assembly of chorion (eggshell) in the med-flyCeratitis capitata
Authors: Mouzaki Despina G. , Margaritis Lukas H. 
Published: June 2020

Among all insect species the eggshell ofDrosophila melanogasteris the most thoroughly studied, consisting of the vitel line membrane, the waxlayer, the inner most chorionic layer the endochorion and the exochorion.Ceratitis capitatais a fruit in festing insect and causes serious destruction to the Greek crop. Our basic biological study aims to help us understand through the structure, the function of the eggshell of the laid egg inside the fruit.For that reason we processed for conventional transmission and scanning E.M., follicles from different developmental stages by dissecting insects into cold Ringer’s solution.Our results revealed that chorionis assembled by a position above the vitel line membrane. The waxlayer is secreted first and then begins the formation of the first series of cavities (fig. 1). These cavities are most probably created by a flocculent material which is found inside them and isused as a scaffolding to the cavities (fig. 2). A second series of cavities is formed over the first.