bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction
Authors: Gulik-Krzywicki T. , Costello M.J. 
Published: June 2020

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.
Structural Changes Leading to Spore Formation in the Myxosporidian Parasite Ceratomyxa Shasta Nobel
Authors: Yamamoto T. , Silliphant R.L. 
Published: June 2020

Ceratomyxa shasta is a myxosporidian effecting mortalities of various species of salmonidae along the western regions of the North American continent.1,2 It is generally accepted from studies of myxosporidian infected t i ssues that the trophozoi tes undergo hi stozoi c development into multi- nucleated complexes which eventually form 2 characteristic spores in the mother cell. Most of the studies of Ceratomyxa have been with the light microscope3 and because of the small size of the parasite much of the structural details were not evident.For the electron microscopic analysis of the sporont and the developing spore of C. shasta two sources of experimentally infected specimens were examined. These were thin sections of free floating developmental forms from the gall bladder and thin sections of intestinal caecae fixed at 2, 7, 14 and 21 days following infection. The trophozoites measuring 20 μm in diameter were observed to increase in number by 14 days, infecting the connective tissue layer between the intestinal epithelial mucosa and the muscularis layer.
Ultrastructure of Isolated Mitochondria from the Renal Cortex after Reversible and Irreversible Ischemia in the Rat
Authors: Coleman S. E. , Duggan J. , Hackett R. L. 
Published: June 2020

Complete renal ischemia causes a series of subcellular changes including chromatin clumping, dilation of endoplasmic reticulum and condensation of mitochondrial matrix followed by swelling of the mitochondria and unfolding of the cristae (1). Most mitochondria are condensed by 15 minutes and half are condensed and half swollen by 30 minutes with the majority of the mitochondria swollen by 60 minutes of ischemia.In this study we have looked at the ability of mitochondria isolated from ischemic rat kidneys to undergo structural energy transformations in the presence of substrate and ADP. Mitochondria were isolated from the inner cortex of rat kidney where initial damage from ischemia occurs. The tissue was diced in the cold, homogenized with a Dounce homogenizer, spun twice at 600 g, and the supernatant at 15,000 g for pelleting of mitochondria.
Some Contributions of Phosphatase and 3,3'-Diaminobenzidine Cytochemistry to Cell Biology
Authors: Novikoff Alex B. 
Published: June 2020

This presentation will highlight cytochemical studies that have illuminated some aspects of structure and function of the endoplasmic reticulum (ER); these have been reviewed recently (1, 2). Phosphatase (Pase) cytochemistry has led to the formulation of new questions regarding secretory mechanisms in a number of endocrine and exocrine cells; it has also made the status of GERL as a distinct organelle considerably firmer. 3,31-diaminobenzidine (DAB) cytochemistry has revealed the presence of an organelle apparently ubiquitous in mammalian cells, the anucleoid peroxisomes(microperoxisomes). DAB cytochemistry has been utilized recently by Gonataset al. (3) to demonstrate that internalized plasma membrane is transported to GERL.Our initial use of Pase cytochemistry to visualize cell organelles included nucleoside diphosphatase (NDPase), thiamine pyrophosphatase (TPPase), and acid Pase (AcPase). NDPase hydrolyzes the diphosphates of inosine, uridine, and guanosine but not cytidine or adenine diphosphates. Since the work of Yamasaku and Hayaishi (4) we have used TPPase and NDPase interchangeably.
PAP, A Secreted Androgen-Dependent Acid Phosphatase of Prostate
Authors: Serrano José A. , Paul Buddha D. , Wasserkrug Hannah L. , Serrano Anna A. 
Published: June 2020

As previously reported (1,2), phosphorylcholine (PC) and D-ephedrine phosphate (DEP) are specific substrates for a non-lysosomal secreted acid phosphatase of prostate (PAP) as opposed to other acid phosphatases, e.g., lysosomal. The specificity of PC and DEP for PAP is due mainly to steric hindrance, a feature that renders these substrates resistant to hydrolysis by other acid phosphatases. This report deals with ultracytochemical results of applying this method to the studies of ventral prostate of castrated, hypophysectomized, testosterone treated (after castration) and normal rats. Male rats (Sprague Dawley) weighing approximately 200 g were used. Animals were sacrificed 4 or 7 days after castration and ventral lobes of the prostate were removed. Hypophysectomized rats were obtained commercially (Taconic Farms, Inc.) and were sacrificed 14 days after hypophysectomy. Rats were injected subcutaneously with 2 mg testosterone in sesame oil for 4 days.Prostates of 4 normal, 4 castrated, 4 hypophysectomized and 4 castrated and testosterone treated rats were studied.
Fluorescent and Immuno-Electron Microscopic Studies of la Antigen Distribution in Normal Human Skin
Authors: Rowden G. , Sullivan A.K. , Lewis M.G. 
Published: June 2020

The I region of the H-2 histocompatability complex in mice is of interest because it plays a major role in numerous immune phenomena.Ia (immune region assoc.) antigens are I region gene products which have been studied mainly in the murine system and have been shown to be present on the surface of B lymphocytes. These glycoproteins are also present in lesser quantities on T cells, macrophages, sperm and fetal liver cells.Studies have been made of the distribution of la antigens in human skin, utilizing a heteroantiserum raised in rabbits. Cell membranes of a B lymphoblastoid cell line were solubilized with Triton X-100 in the presence of a protease inhibitor Trasylol. After clarification by ultracentrifugation the supernatant was passed over a Biogel A 1.5 column. The middle peak (160,000 Mol. Wt.) was then applied by a Con A-Sepharose affinity column.
Maytansine-Induced Mitotic Arrest in Human Lymphoblasts
Authors: Chao Tai-Te , Sullivan John , Krishan Awtar 
Published: June 2020

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.
Ultrastructural Analysis of the Disruption of Ferritin by Acetone
Authors: Massover William H. 
Published: June 2020

Ferritin is the major iron-storage protein in mammals (1, 2). The basic architecture of this large macromolecular complex originally was established in the 1954 electron microscope study by Farrant (3). Each ferritin molecule is a hollow sphere formed by the polymerization of 24 protein subunits; the ferric iron is sequestered within the central cavity as one or more crystallites of a unique mineral (1-4). The protein shell resists depolymerization by many harsh chemical treatments; this stability suggests that the subunit- subunit interactions are very strong. A partial disruption of some protein shells has been produced by certain physical treatments, such as freezing and thawing, boiling and cooling, and, drying and rehydrating (5).Acetone has been used to precipitate ferritin from its aqueous solution (6). Dilution of acetone-precipitated ferritin with distilled water appears to result in complete resolubilization. The present study has examined the ultrastructure of horse spleen ferritin (Calbiochem) after this seemingly innocuous treatment.
Localization of Silver in the Spleen of Argyric Rats by Energy Dispersive X-Ray Analysis Coupled with Scanning and Transmission Electron Microscopy
Authors: Pereira G. 
Published: June 2020

Previous electron microscopic observations of the spleen have revealed the white pulp to be completely separated from the extravasated blood in the surrounding marginal zone by a strategically-located, double layer of reticular cells ensheathing a coarse reticular fiber. Similarly, a single reticular cell layer has been observed to form a continuous investment for all white pulp capillaries. To test the significance of this apparent isolation of the splenic white pulp from the blood, the distribution and composition of silver deposits in the spleen of argyric rats were determined by transmission and scanning electron microscopy coupled with computer-assisted x-ray analysis.Young male albino rats were made argyric by supplying them for many months with drinking water to which 1.5gm per liter of silver nitrate had been added. Specimens from the spleens of control and argyric animals were prepared for conventional transmission electron microscopy by glutaraldehyde-osmium fixation. For scanning electron microscopy, other specimens were fixed in buffered glutaraldehyde, freeze-dried in vacuo, coated with a thin film of gold- palladium and examined in a Cambridge Stereoscan Mark II.
Galactoflavin Induced Riboflavin Deficiency: Effects on Rat Sciatic Nerve, Liver, and Novikoff Hepatoma Cells
Authors: Norton William N. , Savage Howard , Lane Montague , Thurston E. Laurence 
Published: June 2020

Information concerning cell structure and function during riboflavin deficiency is important in view of the finding that treatment of human neoplasms such as lymphosarcoma and Hodgkin's disease with a riboflavin deficient regime and galactoflavin, a riboflavin antagonist, induces partial remission (1).Results from the present study indicate that riboflavin deficiency severely affects the structural integrity of myelin lamellae (Fig. 1). The myelin sheath undergoes a form of dissociation or separation, in essence a pulling apart of adjacent membranes. In addition, there are marked degrees of fragmentation not only of the myelin membranes but also of the axolemma. These results correlate well with clinical data which reveal that various sensory and motor pathways are adversely affected by a riboflavin-deficient diet (2). The riboflavin deficiency produces no discernible effects upon organelle content of neurons. Organization and integrity of microtubules, neurofilaments and mitochondria are maintained at least until fragmentation of the axolemma occurs. Nonmyelinated nerve fibers do not appear to be affected ultrastructurally by the deficiency.
Ultrastructure and Analysis of Striae
Authors: Kischer C.W. , Arem A.J. 
Published: June 2020

Cutaneous striae are believed to occur in glucocorticoid-stimulated skin and have been morphologically identified with a rupture of thick elastic fibers and a straightening of collagen bundles.The fact that striae are usually flattened or depressed areas would tend to suggest they are not true closed dermal wounds and would be metaboli- cally inactive. To examine this possibility we have analyzed striae by light and electron microscopy and by preliminary biochemical assays. Striae were removed from a skin wedge taken from a 45 year old woman undergoing an abdominal lipectomy. The age of the striae was probably several years. The tissues to be studied morphologically were fixed in Karnovsky's fluid while those reserved for biochemical assay were either used fresh or frozen.The striae portion was excised from adjacent clinically-normal skin and data from each area was compared.No apparent reduction of elastic tissue occurs throughout the breadth or depth of the stria area.
SEM of Hepatocytes and Biliary Passages in Goldfish Liver
Authors: Nopanitaya Waykin , Grisham Joe W. , Carson Johnny L. 
Published: June 2020

An interesting feature of the goldfish liver is the morphology of the hepatic plate, which is always formed by a two-cell layer of hepatocytes. Hepatic plates of the goldfish liver contain an infrequently seen second type of cell, in the centers of plates between two hepatocytes. A TEH study by Yamamoto (1) demonstrated ultrastructural differences between hepatocytes and centrally located cells in hepatic plates; the latter were classified as ductule cells of the biliary system. None of the previous studies clearly showed a three-dimensional organization of the two cell types described. In the present investigation we utilize SEM to elucidate the arrangement of hepatocytes and bile ductular cells in intralobular plates of goldfish liver.Livers from young goldfish (Carassius auratus), about 6-10 cm, fed commercial fish food were used for this study. Hepatic samples were fixed in 4% buffered paraformaldehyde, cut into pieces, fractured, osmicated, CPD, mounted Au-Pd coated, and viewed by SEM at 17-20 kV. Our observations were confined to the ultrastructure of biliary passages within intralobular plates, ductule cells, and hepatocytes.
Contraction Bands in Human Hearts: Pathology or Artifact?
Authors: Adomian G.E. , Laks M.M. , Billingham M.E. 
Published: June 2020

With increasing use of myocardial biopsy as a diagnostic tool, different criteria of pathology have evolved from tissues obtained from biopsy and post mortem specimens. Since contraction bands have been present in myocardial tissue associated with various cardiac pathological states, their presence have been interpreted as being a part of these pathological processes. For example, CB have been used as a morphological index of pathology in conditions such as ischemia, cardiomyopathy, and catecholamine toxicity. We recently reported that contraction bands may be produced artifactually by the biopsy procedure in the fresh, but not the post mortem or perfused fixed normal rat heart (1). In order to establish the generality of these results we undertook the present study,the aim of which was to determine the incidence and significance of CB in biopsies from the normal human heart.Biopsy specimens were obtained from twelve normal young individuals who had recent irreversible traumatic damage to their brain.
SEM Cold Stage Techniques for the Observation of Vegetative and Floral Apices of Oat (Avena sativa L.) Plants
Authors: Kirchoff B. K. , Allard L.F. , Bigelow W.C. 
Published: June 2020

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.
SEM Study of Insect Tissue Using Ethanol-Infiltrated Cryofracture Followed by Critical Point Drying
Authors: Sanford Malcolm T. , Dietz Alfred 
Published: June 2020

Transmission electron microscopy has been used for most ultrastructural study of insect tissue. This is particularly true for investigations of glands associated with the insect epidermis and cuticle (1). The advent of ethanol-infiltrated cryofracture of biological tissue followed by critical point drying, however, enables closer examination of surface topography and three dimensional conformation of glands and other structures associated with the insect cuticle by scanning electron microscopy (2).In the queen honey bee (Apis mellifera L.), a wide band of gland cells is located beneath tergites three, four and five of the abdomen, called subepidermal glands (3). Epidermal cells and modified epidermal cells, tormogen cells, are also found beneath the cuticle near the subepidermal glands (4).Scanning electron microscopy of ethanol-infiltrated fractured tergites of the queen honey bee which have been critical point dried revealed that the subepidermal gland cells were spherical in shape (Fig. 1).
Ultrastructural Characterization of 18-24 Hr. Neurospora Crassa Hyphae by Freeze-Fracture Techniques
Authors: Howard K. S. , Socolofsky M. D. , Braymer H. D. , Clisham P. R. 
Published: June 2020

The ultrastructure of Neurospora crassa hyphae has been characterized primarily by the thin section technique. Since the original work of Shatkin and Tatum1, however, the quality of thin sections has been hindered by difficulty in fixing, embedding, and staining. A recent study of N. crassa ascospores compared the ultrastructure as revealed by freeze-etch to that revealed by thin sections, demonstrating the utility of the freeze-etch method when applied to organisms that have been difficult to prepare for EM observation2. The present study applies freeze-fracture to II. crassa in an attempt to confirm and increase the ultrastructural information presently available.Neurospora crassa strains 73a and 74A were grown in Vogel's minimal citrate medium for 18 to 24 hours. The resultant hyphae were treated with 3% glutaraldehyde in 0.1 M phosphate buffer for 2 hours followed by immersion in 30% glycerol for 1 hour or transferred directly to 30% glycerol from growth medium without glutaraldehyde fixation.
Development of the Acrosome During Spermiogenesis in Arion Hortensis Ferussac (Stylommatophora, Pulmonata)
Authors: Maxwell W. L. 
Published: June 2020

It has been suggested that in internally fertilising animals the acrosome is of reduced importance where species recognition occurs at the individual rather than cellular level (1).However, a complex acrosome is present in the spermatozoon of Arion hortensis. and a specialised accessory structure is formed during acrosomal development.The proacrosomal granule is deposited at the presumptive nuclear apex early in spermiogenesis by the Golgi apparatus - but subsequent development occurs without any Golgi association. The granule is initially oblong when viewed in longitudinal section being 400nm long. There is no visible substructure as shown in Fig.l. During spermiogenesis the acrosome parallels the elongation of the nucleus. At about mid-spermio- genesis the columnar proacrosome is 600nm long and Fig.2 shows some internal differentiation. A central rod of material is visible with a basal concavity which is closely associated with the anterior tip of the maturing nucleus.
Cerebral Tissue Response in Chronic Electrode Implantation
Authors: Dodson R.F. , Chu L.W-F , Ishihara N. 
Published: June 2020

The extent of damage surrounding an implanted electrode in the cerebral cortex is a question of significant importance with regard to attaining consistency and validity of physiological recordings. In order to determine the extent of such tissue changes, 150 micron diameter platinum electrodes were implanted in the cortex of four adult baboons, and after eight days the animals were sacrificed by whole body perfusion with a 3% glutaraldehyde in 0.1M phosphate fixative.The calvarium was carefully removed and the electrode tracts were readily discernible in the firm, glutaraldehyde fixed tissue.Careful dissection of the zone of the electrode tract resulted in a small block which was further sectioned into tip, mid-tract and surface areas. Ultrastructurally, damage extended from the electrode sheath to the greatest extent of from 0.2 to 3.5 mm.
Ultrastructural Morphology of the Anagen Stage Hair Follicle of Male Beagle Dogs
Authors: Al-Bagdadi F. A. , Titkemeyer C. W. , Lovell J. E. 
Published: June 2020

Skin biopsy samples were collected monthly from the lateral sides of 9 male Beagle dogs over a period of 1 year. The samples were fixed in 3% gluteral- dehyde and post fixed in 1% osmium tetroxide using phosphate or S-Collidine as buffers. They were dehydrated, embedded in Epon 812, sectioned with an LKB Ultrotome III, and stained with Reynolds' lead citrate and 1% uranyl acetate. They were examined and photographed by use of an RCA-3H electron microscope.The dermal papilla during anagen consisted of fibroblast-like cells some of which had cytoplasmic processes. The cytoplasm contained many mitochondria. (Fig. 1) The cells of the dermal papilla were either peripherally arranged spindle-shaped cells or polygonal cells. The basement membrane was either related to the fibroblast cytoplasmic processes or was free of the cytoplasmic processes but with a thick zone composed of fibers, granular ground substance and spaces.
The Effects of Phenyl Mercuric Acetate (PMA) on the Ultrastructure of the Paint Mildew, Aureobasidium Pullulans
Authors: Crang Richard E. , Pechak David G. 
Published: June 2020

For over 30 years Aureobasidium pullulans (DeBary) Arnaud has been considered the primary fungal agent involved in mildew-induced defacement of painted surfaces (1). Although mercury compounds have been incorporated into the paints as mildewcides, little is known relative to the action of mercury on fungal cells (2). The purpose of this study is to determine the ultrastructural effects of a commonly used mildewcide, phenyl mercuric acetate (PMA), on A. pullulans.All experimental cultures of A. pullulans were grown on a defined medium containing: (NH4)2S04, 3.0 g; K2HP04, 1.0 g; MgSO4.7H20, 0.5 g; KC1, 0.5 g; FeSO47H2O, 0.1 g; sucrose, 10.0 g per liter dist. H2O. The medium was solidified with 2 per cent agar. Two sets of media were inoculated with a blastospore suspension of A. pullulans. One set contained only the above defined medium, while the second set contained 200 ppb (5xlO-7M) PMA supplementing the defined medium.