bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alteration in vitreal structure following C3F8 injection
Authors: Panessa-Warren Barbara J. , Maisel James , Warren John B. 
Published: June 2020

Although the use of intraocular perfluorocarbon gases has been demonstrated to be a clinically useful procedure for retinal compression and diagnostic procedures, the effect of the gas expansion to 90% ocular volume causes the displacement of the vitreous. This investigation examines the morphological changes in the vitreous of 36 rabbit eyes following C3F8 intravitreal gas injection, by light (LM), transmission (TEM) and scanning (SEM) electron microscopy. Lincoff et al have demonstrated that C3F8gas exhibits a fourfold expansion of its volume at 3-4 days after injection into the vitreous. Following expansion the gases disappear logarithmically with the volume of the bubble following first order decay kinetics. For the rabbit, the C3F8 half-life is six days, with the total reabsorption of the gas in 40 days. To determine whether initial structural changes following gas injection eventually resolved, eyes were studied at 3, 6, 8, 16, 41 and 64 days post injection.Four pigmented and 14 albino mature (3-4 Kg) rabbits were anesthetized and given topical proparacaine anesthetic prior to injection into the inferior vitreous cavity with 0.1, 0.3 or 0.4 cc filtered C3F8. An indirect ophthalmoscope was used to direct the 30 gauge needle to a position 2-3 mm posterior to the limbus. In each case, the contralateral eye was used as the normal control. Animals were euthanized with intravenous T61 solution and the eyes immediately enucleated and frozen in liquid nitrogen. While still submerged in liquid nitrogen the tissue was placed in a deep freeze and allowed to equilibrate to −80°C for 24 hrs. Eyes were cryosectioned at −20°C and the sections placed on prechilled glass slides, cover slips, sapphire wafers or pyrolytic graphite planchets. For LM histochemistry, the frozen sections were placed in 95% ethanol 10 min and stained using a Papanicolaou method. To identify collagen, Van Gieson's picric acid fuchsin and 2.5% aniline blue were used. Proteoglycans were stained with pH 1 or pH 1.5 alcian blue or 0.5% ruthenium red. Some cryosections were freeze dried or fixed in 3% glutaraldehyde, dehydrated and dried by the critical point method (CO2) for SEM examination of an AMRay 1000A equipped with a lanthanum hexaboride gun at Brookhaven National Laboratory, Upton, NY. Tissue for routine TEM was fixed immediately following enucleation in 3% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4), post fixed in 1% aqueous OsO4, dehydrated in acetone and embedded in Epon 812. To identify and retain proteoglycans, some eyes were fixed in 2% glutaraldehyde in 0.1 M cacodylate containing 0.01% ruthenium red. Both unstained and stained (Ur-acetate and Pb-citrate) plastic thin sections were examined at 80 kV on a Philips 300.
Identification of viruses causing gastroenteritis in central florida: A one-year survey
Authors: Price G. , Franklin R. , Cerezo L. 
Published: June 2020

Acute gastroenteritis is known to cause millions of deaths worldwide, many of which are attributable to viral agents. Death is caused by cardiac arrest as a result of dehydration and electrolytic imbalance brought on by vomiting and diarrhea. The majority of these deaths occur in developing countries where public sanitation and health care is at a minimum. Deaths from gastroenteritis in the United States have dropped considerably since the 1900's because of improvements in health care.Viruses may be identified as the pathological agent of gastroenteritis by a variety of methods, one of which is morphological identification by electron microscopy (EM). Electron microscopy offers a rapid method for identifying viruses regardless of serotype, but requires a concentration of viral particles of between 105- 106/ml to be effective. This concentration problem can be overcome by ultracentrifu-gation, although detection of Norwalk Agent requires immuno-electron microscopy.
Neotendon formation using a collagen fiber tendon prosthesis
Authors: Wasserman Arthur J. , Kato Y. Pedro , Ganim Don , Dunn Michael G. , Silver Frederick H. 
Published: June 2020

Damage to tendons occurs commonly during physical activity. Tendons can be repaired using natural and synthetic materials. The purpose of a tendon prosthesis is to provide support while allowing a new tendon to form. The newly formed tendon should have morphological and mechanical properties identical to the normal tissue. Neotendon formation can be assessed ultrastructurally to compare its morphology with that of mature tendon. The extent of cell ingrowth, collagen fibril diameter, proteoglycan (PG)/collagen interactions and collagen fibril bundle formation are all morphological criteria to evaluate the status of tendon repair. The purpose of this study is to ultrastructurally evaluate the mechanism by which a reconstituted collagen fiber tow is replaced by neotendon.Collagen fibers of the tow were prepared from insoluble type I collagen derived from bovine corium and crosslinked by severe dehydration followed by treatment with cyanamide, as previously described. A tow of 250 fibers was coated with a 1% type I collagen dispersion to form a thin ribbon prosthesis. Mature New Zealand white rabbits weighing 6-7 lbs were anesthetized and the Achilles tendon was removed and replaced with a sterile collagen fiber tow. At 3 and 10 weeks postoperatively the explants were fixed for conventional TEM and SEM as previously described.
Characterization of N-Vinyl pyrrolidone grafting into silicone rubber
Authors: Lee R. , Greer R. 
Published: June 2020

Since 1960, hydrogels have been utilized in a large number of biomedical products. The poor mechanical strength of hydrogels necessitates the use of a stronger support material in order to provide structural reinforcement. Methods of surface preparation include radiation grafting. Parameters of importance for grafting N-vinyl pyrrolidone (NVP) into silicone rubber include the choice of solvent, monomer concentration, radiation dose and use of selective inhibitors. Post irradiation extraction of homopolymer and monomer from the silicone rubber substrate after grafting is an important step. NVP grafted polymers can be stained by many dyes for depth of penetration studies.Fourteen cm sections of non-reinforced Silastic® (silicone rubber, Dow Corning) tubing, 0.078″x0.125″, were boiled for three 1 h periods in aqueous 2.0% sodium bicarbonate solution. Prior to irradiation, monomer solutions used to fill tubes were bubbled with nitrogen for at least 30 min. Several monomer/solvent formulations (100% NVP; 80% NVP/20% methanol; and 60% NVP/40% methanol, and gamma irradiation doses (50, 150, 200 and 250 krad) were used.) After irradiation, samples were flushed with either acetone/methanol (50:50 v/o) or ethanol/water (50:50 v/o) , followed by three 30 min agitated washes in the same type of solution. To test the effect of methanol concentration on rim thickness measurements, 0.5 cm lengths of cleaned Silastic , acetone/methanol extracted Silastic®, and grafted tubing of 100% NVP and 80% NVP/20% methanol formulations were immersed in 0.1% acid fuchsin stains in 10, 50, and 100% methanol for 48 h. After rinsing and drying, cross sections were cut, and the penetration depth of the stain (i.e., graft depth) was measured.
Localization of two structural wall proteins in an insect spermatophore by immunoelectron microscopy
Authors: Schuette J. L. , Happ G. M. 
Published: June 2020

Spermatophores are acellular protein sacs which package sperm for transport. They are highly ordered structures derived from secretions that self-assemble in extra- cellular spaces. The mealworm spermatophore emerges from the male in an unexpanded state and consists of a multilayered fibrous outer wall, an organized inner core and a lumen containing semen. The spermatophore expands inside the female as its core is extruded and molded into new wall material. We are interested in the assembly and maturation of the spermatophore and have developed monoclonal antibodies which recognize epitopes of two different wall proteins, each secreted from a distinct cell type. We have employed immunoelectron microscopy (ABC Technique) to determine the location of these proteins in the wall and to examine their fate during the expansion process.Spermatophores were collected from copulating male mealworms (Tenebrio molitor). Some were allowed to fully expand. Samples were fixed in 1% formaldehyde and 0.5% glutaraldehyde in 0.1M phosphate buffer, pH = 7.2, for 2 h; dehydrated through alcohol and embedded in Epon.
Effect of depolarization by potassium proprionate on synaptic vesicle diameter and distribution of the snake motor endplate
Authors: Hendricks Gregory , Coniglio Lisa , Marshall Ian , Searl Tim , Parsons Rodney 
Published: June 2020

The morphological effects of elevated potassium (K+) at the neuromuscular junction of garter snake twitch muscle fibers were examined in vitro. Elevated K+ depolarizes the motor neuron terminals and causes quantal release of acetylcholine. It has been shown in amphibians that prolonged (30-60 min) depolarization with high K+ depletes terminals of synaptic vesicles ; but causes no change in the average diameter of the vesicles. In the snake, however, we have shown previously that miniature endplate currents (MEPCs) are present at high frequency even after 1-2 hours of exposure to high K+ . This indicates that in the snake, synaptic vesicles are not totally depleted by depolarization with high K+. In this study, we examined the effect of depolarization with high K+ on the distribution and diameter of synaptic vesicles.Intercostal muscle preparations were exposed for 15 minutes to Ringer's + solution containing either a control (1.2mM) or high (70mM) concentration of K+ Preparations were fixed immediately in 1% glutaraldehyde for 15 minutes and washed with Millonig's buffer. The whole mount muscle preparations were then fixed for 1 h in 2.5% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2; rinsed three times in fresh buffer and post-fixed in 2% OsO4 in the same buffer for 30 min, rinsed in fresh buffer and dehydrated in a graded ethanol series to 100% and then transferred into a 2% solution of uranyl acetate for 20 min to en-block stain the whole mounts. The preps were then transferred back to 100% ethanol to complete the dehydration and embedded in a mixture of Embed 812/Araldite 502 (Hard) between two microscope slides that had been precoated with Formen- Trennmittel Liquid Release Agent and polymerized overnight at 70°C.The whole mounts were then removed from the microscope slides and examined on a compound light microscope where the neuromuscular junctions on the twitch muscle fibers could be identified, marked and cut out of the preps. These pieces of the whole mounts were then remounted into a slot on the end of a pre-cast Embed-Araldite block with a drop of fresh resin and polymerized.
A technique for protecting delicate specimens during processing
Authors: Mount R.J. , Harrison R.V. 
Published: June 2020

The sensory end organ of the ear, the organ of Corti, rests on a thin basilar membrane which lies between the bone of the central modiolus and the bony wall of the cochlea. In vivo, the organ of Corti is protected by the bony wall which totally surrounds it. In order to examine the sensory epithelium by scanning electron microscopy it is necessary to dissect away the protective bone and expose the region of interest (Fig. 1). This leaves the fragile organ of Corti susceptible to physical damage during subsequent handling. In our laboratory cochlear specimens, after dissection, are routinely prepared by the O-T- O-T-O technique, critical point dried and then lightly sputter coated with gold. This processing involves considerable specimen handling including several hours on a rotator during which the organ of Corti is at risk of being physically damaged. The following procedure uses low cost, readily available materials to hold the specimen during processing ,preventing physical damage while allowing an unhindered exchange of fluids.Following fixation, the cochlea is dehydrated to 70% ethanol then dissected under ethanol to prevent air drying. The holder is prepared by punching a hole in the flexible snap cap of a Wheaton vial with a paper hole punch. A small amount of two component epoxy putty is well mixed then pushed through the hole in the cap. The putty on the inner cap is formed into a “cup” to hold the specimen (Fig. 2), the putty on the outside is smoothed into a “button” to give good attachment even when the cap is flexed during handling (Fig. 3). The cap is submerged in the 70% ethanol, the bone at the base of the cochlea is seated into the cup and the sides of the cup squeezed with forceps to grip it (Fig.4). Several types of epoxy putty have been tried, most are either soluble in ethanol to some degree or do not set in ethanol. The only putty we find successful is “DUROtm MASTERMENDtm Epoxy Extra Strength Ribbon” (Loctite Corp., Cleveland, Ohio), this is a blue and yellow ribbon which is kneaded to form a green putty, it is available at many hardware stores.
CFM holey films
Authors: Olson R. A. 
Published: June 2020

Chloroform-formvar-mica (CFM) can be used to make holey films in the simplest and most reliable procedure described to date. A wide variety of approaches have been devised to produce thin membranes with holes in them. Hayat (1978) provides an excellent historical overview of these perforated film techniques. They range from complex and cumbersome to relatively simple, but even these simpler techniques require either special solutions or incorporate time-dependent steps which may yield variable results. The CFM technique suffers from neither of these drawbacks; the steps are outlined below.Procedure:l. Dip a freshly cleaved mica strip into a 0.25% solution of formvar in chloroform and withdraw it at a slow, even rate.
2. Wick off excess solution, allow to dry for about one minute, and trim the formvar coated lower edges of the strip with scissors.
3. Score the formvar membrane with a razor blade just below the “high water mark” and float it onto distilled water.
Changes in the plastid ultrastructure during greening in cultured soybean cells
Authors: Gillott M.A. , Erdös G. , Buetow D. E. 
Published: June 2020

Mesophyll cells isolated from soybeans (Glycine max, L. Merr. var. Corsoy) can be grown photoautotrophically in suspension culture. The SB-P cell line can be bleached by maintaining them in total darkness in sucrose supplemented media for several weeks, and will regain photosynthetic competency when returned to the light. This system is ideally suited for the study of gene regulation and the biochemical and ultrastructural changes which occur during the greening process.Cells were fixed for electron microscopy after 8 weeks of growth in total darkness and at intervals of 1 h to 12 d after transfer to the light. Chlorophyll measurements were determined for each sample. For transmission electron microscopy, the cells were fixed for 1-2 h in 4% glutaraldehyde in 0.1M Pipes buffer, pH 7.4, washed in the same buffer, then postfixed for 1 h in 1% OsO4 in Pipes, pH 6.8. Following a graded ethanol dehydration series the cells were transferred into propylene oxide and embedded in Epon. Sections were stained with uranyl acetate and observed on a JEOL 100C TEM operated at 80 kV.
A Scanning Electron Microscope study of the pecan phylloxera, Phylloxera devastatrix, with observations on emergence
Authors: Hall M.J. , Clawson R. C. , Saunders C. , Shelton R. R. 
Published: June 2020

The pecan phylloxera, Phylloxera devastatrix Pergande, is a small, cecidogenic insect found throughout the native range of the pecan tree. Infestations of P. devastatrix have been reported to cause reductions in nut quality and quantity, premature defoliation, and shoot dieback. Galls formed by P. devastatrix are an alternate host for the larvae of the hickory shuckworm, Cydia caryana Fitch. Little information exists on the biology and ecology of this insect. The objective of this study was to examine the emergence patterns of P. devastatrix on different pecan cultivars to determine if variability in bud-break between cultivars effected emergence. This study also provided an opportunity to study gall formation and the life cycle in detail.P. devastatrix overwinter as an egg within the body of the sexual female (Figs. 1 & 2). Upon hatching, the stem mother moves to the bud and begins feeding (Figs. 3 & 4). As the stem mother feeds, a gall begins to form around the insect (Fig. 3). Eggs deposited within the gall by the mature stem mother (Fig. 6) hatch into apterous and alate females (Fig. 7). Eggs produced by these females hatch into sexual males and females (Fig. 8 & 9). After mating, an egg is produced within the body of the female. The female next seeks a place on the tree to overwinter, thus completing the cycle. Stoetzel described the development of the stem mother and apterous and alate females as hemimetabolous (incomplete metamorphosis), and that of the sexual males and females as holometabolous (complete metamorphosis). Gal1s of p. devastatrix are classified as cover galls. The upwalling of the plant tissue around the insect, characteristic of this type of gall, can be clearly seen in the SEM photographs (Figs. 3 & 5).
Quantitative analysis of post-embedding immunogold Electron Microscopy with differently sized labelling gold particles
Authors: Gu J. , D'Andrea M. 
Published: June 2020

The post-embedding immunogold staining technique is a powerful tool in localizing tissue antigens at the ultrastructural level. The highly electron dense colloidal gold particles are easily visible under electron microscope and the differently sized gold particles allow a simultaneous demonstration of more than one tissue antigens in the same grid. The sizes of the commercially available labelling gold particles range from 1 nm to 40 nm. It is generally believed that the smaller the gold particles the better the detecting sensitivity of the technique. However, no quantitative data in this regard is available. We carried out an experiment to assess the detecting sensitivities of differently sized labelling gold particles in the post-embedding electron microscopic indirect immunogold staining method using atrial natriuretic peptide (ANP) in rat atria as a model.ANP is a newly discovered cardiac hormone with 28 amino acids. In the heart it is located exclusively in the specific electron dense granules in the cytoplasm of atrial cardiocytes. The high concentration and the well defined location of this tissue antigen makes it an ideal model to evaluate the detecting sensitivities of immunostaining techniques.
Biological photocathodes: Complexes of chlorophylls and hemes examined by photoelectron microscopy
Authors: Griffith O.H. , Habliston D.L. , Birrell G.B. , Skoczylas W.P. , Hedberg K.K. 
Published: June 2020

Chromophore binding proteins are important in cell bioenergetics. They are, however, difficult to distinguish by electron microscopy because the atomic composition and hence scattering properties are not very different from those of other proteins. Photoemission is one relatively unexplored property of chromophores that offers a solution to this problem. Essentially all biological specimens exposed to radiation of sufficiently high energy, typically in the ultraviolet region of the spectrum, emit electrons (photoelectrons). The photoelectrons are accelerated and imaged in a photoelectron microscope as diagrammed in Fig. 1. Since the photoelectrons originate at or near the sample surface, photoelectron microscopy is essentially a surface technique. Up to now biological applications of photoelectron imaging have been restricted by the relatively low magnifications attainable due to the low emissivity of biological specimens. The goal of this study is to convert the biological surface into a sensitive photocathode while retaining the differences in photoemission of the various components, such as the chromophores, which provide important functional information in the biological preparations.We find that the photoemission of biomolecules can be greatly increased by exposure to a very thin layer of cesium (approximately 1 nm thick). The free cesium evaporates, leaving behind cesium atoms that interact with the surface components. One mechanism is evidently electron transfer from cesium to the chromophores, resulting in charge transfer complexes (ion radical salts). Other mechanisms are almost certainly also involved. An example of the dramatic improvement in photoemission, and hence magnifications attainable, is shown in Fig. 2.
Signs of nerve regeneration following pancreas transplantation in an insulin-dependent diabetic with neuropathy
Authors: Beggs J.L. , Johnson P.C. , Olafsen A.G. , Cleary C. , Watkins C.J. , Targovnik J. , Koep L. 
Published: June 2020

Nerve disease is a common complication of diabetes mellitus. Hyperglycemia directly or indirectly causes structural damage and functional impairment of nerve fibers. Despite conventional therapy, there continues to be a substantial incidence of diabetic complications. Development of complications is thought to be due to abnormal fluctuations in blood glucose levels. The number of pancreas transplants performed for the treatment of diabetic complications has increased dramatically in the last few years. Unlike conventional therapy, functional pancreas grafts provide normal fasting blood glucose levels, near-normal glucose tolerance, and normal levels of glycosylated hemoglobin. In this report, we address the following question: will functional pancreas grafts prevent or reverse the structural nerve damage caused by diabetes mellitus?A 53 y/o man developed insulin-dependent diabetes at age 35. Nephropathy, retinopathy, and neuropathy developed despite conventional insulin therapy. To treat these complications, pancreas segment transplant was performed. The donor was his identical twin. The recipient was treated with low-dose immunosuppressive drugs (azathioprine and prednisone). He has remained euglycemic for 3 years and requires neither insulin therapy nor oral hypoglycemic agents. Clinical examinations during the 3 years post-transplantation have revealed progressive improvement in vision, nerve function and a stabilization in renal function.
MDX mouse myopathy II: Degenerative changes in centronucleated fibers from mice of different ages
Authors: Geissinger H.D. , Rhodes P.A. 
Published: June 2020

Ultrastructural features of centronucleated (regenerating) fibers of ‘mdx’ mice have been reported in three different papers and in all three, different features of these fibers were described in some detail. Thus, in one paper “abortive attempts at regeneration” in very young fibers, in another early degeneration of regenerating fibers and in the third paper “healthy” regenerating fibers, as well as degenerating myotubes were shown. We show the probable pathogenesis of degeneration of centronucleated fibers in ‘mdx’ mice.METHODS: Tibialis anterior muscles from 22-, 25-, 41-, 61- and 99-days-old C57BL/10ScSn/MDX mice were pinned on corkboard in a relaxed state, prefixed for 30 minutes in glutaraldehyde followed by routine processing for TEM.RESULTS: In a 41-days-old ‘mdx’ mouse a fiber which had apparently fully regenerated from a previous episode of necrosis is shown in FIG. 1. Since there are no pathological changes in this fiber, it will serve as a control. The nucleus has a fairly prominent nucleolus and there are no lesions in the
myofibrils and the rest of the sarcoplasm.