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At least 1,531 records · Page 85Linked to original sources
PubMed1990

Response to epidermal growth factor of skin fibroblasts from donors of varying age is modulated by the extracellular matrix.

The present study was undertaken to investigate the effect of epidermal growth factor (EGF) on the biosynthetic activity of skin fibroblasts from donors of varying age and the modulation of their response to this growth factor by culture in a three-dimensional extracellular matrix. When cultured in monolayer on plastic or at the surface of a collagen gel, EGF specifically inhibited collagen synthesis whatever the age of the donor (from 17 to 84 years, n = 11). This inhibition was paralleled by a significant decrease in the steady-state level of procollagen type I mRNAs. When embedded in a three-dimensional floating collagen lattice, EGF stimulated the non-collagen protein (NCP) synthesis in fibroblasts from younger donors (5 out of 6) while fibroblasts from the older ones were not affected. Collagen production by fibroblasts from younger donors was not inhibited as in monolayer (some being even stimulated) while that of the older donors was inhibited as observed in monolayer. The steady-state level of procollagen type I mRNA was not modified by EGF in the three-dimensional culture. No significant difference was observed in the affinity and the number of EGF receptors of the fibroblasts on plastic or embedded in a collagen lattice between young and aged donors. Our results suggest that the environment of the cells can modulate the reactivity to EGF and reveal differences related to in vivo aging.

Adolescent↗
PubMed2000

Characteristics of human chondrocytes, osteoblasts and fibroblasts seeded onto a type I/III collagen sponge under different culture conditions. A light, scanning and transmission electron microscopy study.

Hyaline cartilage has only a limited capacity of regeneration, thus, lesions of articular cartilage can lead to early osteoarthrosis. Current concepts in conservative orthopedic therapy do not always lead to satisfying results. As one new attempt to facilitate cartilage repair, autologous transplantation of articular chondrocytes is investigated in different assays. This study was designed to create a resistible and stable cell-matrix-biocomposite with viable and biosynthetically active human chondrocytes, osteoblasts or fibroblasts. This biocomposite might serve as an implant to treat deep osteochondral defects in the knee. We collected cartilage, spongiosa and skin probes from healthy patients undergoing hip-surgery and enzymatically liberated the chondrocytes, seeded them into culture flasks and cultured them until confluent. The spongiosa and the skin samples were also placed in culture flasks and cells cultured until confluent. After 4-6 weeks, cells were trypsinized and grown on a type I/III collagen matrix (Chondrogide, Geistlich Biomaterials, Wolhusen, Switzerland) for 7 days in standard Petri dishes and in a special perfusion chamber culture system. As controls, cells were seeded onto plastic surfaces. Then scaffolds were fixed and embedded for light microscopy and electron microscopy by routine methods. Light microscopically, chondrocytes grown on the surface of the scaffold form clusters or a dense layer of sometimes rather fibroblast-like and sometimes roundish, chondrocyte-like cells. Only a few cells grow deeper into the matrix. In transmission electron microscopy, the cells have a rather chondrocyte-like morphology which emphasizes the matrix-induced redifferentiation after dedifferentiation of chondrocytes in monolayer-culture in culture flasks. Chondrocytes on plastic surfaces have a spinocellular aspect with little signs of differentiation. Grown on Chondrogide, cells are more roundish and adhere firmly to the collagen fibrils of the scaffold. Osteoblasts grown on the collagen scaffold and examined by light microscopy form a thin cell-layer on the surface of the matrix with a reticular layer of dendritic cells underneath this sheet. Transmission electron micrographs show spinocellular and flat cells on the collagen fibrils. Scanning electron micrographs show large dendritic osteoblasts on plastic and a confluent layer of flattened, dendritic cells on the collagen scaffold. Fibroblasts form a thick multi-layer of typical spinocellular cells on the collagen matrix. Fibroblasts grown on plastic surfaces and examined by scanning electron microscopy also show a dense layer of fibroblast-like cells. For all three different types of cells no morphological differences could be seen when comparing cultivation in the perfusion culture system to cultivation in standard Petri dishes, although mechanical stress is believed to induce differentiation of chondrocytes. Especially the observed partially differentiated chondrocyte-matrix biocomposite might serve as an implant to treat deep cartilage defects, whereas osteoblasts and fibroblasts seem to be less suited.

Aged↗
PubMed2006

Removal of metallic stent by using polyflex stent in esophago-colic anastomotic stricture.

Benign strictures or anastomoses of the esophagus can be treated by stents. However, short-term and long-term complications, including migration and hyperplastic tissue reaction can occur. Bowel reconstruction by interposition has been performed after esophagectomy. Stricture of cervical anastomosis is an important late complication. Self-expandable metallic stents have been used to improve this problem. To remove the obstructed metallic stent, self-expandable covered plastic stents can be used. Herein we present the removal technique of tissue-embedded self-expandable metallic stents by using self-expandable covered plastic stents after colon interposition in a case of benign cervical anastomosis of the esophagus due to caustic stricture.

Adult↗
PubMed1992

Parallel induction by glucose of adherence and a polysaccharide antigen specific for plastic-adherent Staphylococcus epidermidis: evidence for functional relation to intercellular adhesion.

The initial attachment and the accumulation of Staphylococcus epidermidis on polymer surfaces in multilayered cell clusters embedded in amorphous slime, which together lead to the plastic-adherent phenotype detected by the adherence assay used in this study, have been proposed to be major virulence factors of these bacteria. An antigen specific for plastic-adherent S. epidermidis strains was detected by an indirect immunofluorescence test using absorbed antiserum raised against the strongly plastic-adherent S. epidermidis 1457. A coagglutination assay was established, which allowed the quantitation of the antigen in bacterial extracts under different physiologic growth conditions. Expression of the antigen and of plastic adherence depended significantly on the presence of glucose in the growth medium. Parallel to increased plastic adherence, a 32- to 64-fold increase in the amount of the antigen was detected in bacterial extracts of cells grown in tryptone soya broth (TSB) compared with that in extracts of cells grown in TSB lacking glucose. A parallel time-dependent increase of plastic adherence and expression of the antigen was observed after stimulation by glucose of stationary-phase cultures of plastic-adherent S. epidermidis strains grown in TSB lacking glucose. The antigen consisted most probably of polysaccharide, because its immunologic reactivity was completely abolished by periodate oxidation but was resistant to protease digestion. A significant proportion of cells of plastic-adherent as compared with nonadherent S. epidermidis strains grown in TSB were located in large cell clusters exceeding 50 cells, which completely disintegrated after periodate oxidation of the cell preparations. Periodate oxidation of adherent bacterial films in situ led to release of the adherent cells from the plastic surface. These results strongly indicate a functional relation of the antigen to adherence of S. epidermidis to polymer surfaces, most probably by mediating intercellular adhesion of cells leading to accumulation in multilayered cell clusters.

Agglutination↗
PubMed2006

Searching for plasticity in dissociated cortical cultures on multi-electrode arrays.

We attempted to induce functional plasticity in dense cultures of cortical cells using stimulation through extracellular electrodes embedded in the culture dish substrate (multi-electrode arrays, or MEAs). We looked for plasticity expressed in changes in spontaneous burst patterns, and in array-wide response patterns to electrical stimuli, following several induction protocols related to those used in the literature, as well as some novel ones. Experiments were performed with spontaneous culture-wide bursting suppressed by either distributed electrical stimulation or by elevated extracellular magnesium concentrations as well as with spontaneous bursting untreated. Changes concomitant with induction were no larger in magnitude than changes that occurred spontaneously, except in one novel protocol in which spontaneous bursts were quieted using elevated extracellular magnesium concentrations.

Animals↗
PubMed1986

A possible differentiation of anterior pituitary cells in collagen gels into neurons.

Dispersed cells from anterior pituitary glands of male rats were cultured embedded in collagen gels or on a plastic surface. After 6 or more days in culture, cells in collagen produced more prolactin than those on plastic. The cultures in collagen had fewer fibroblasts than those on plastic. Many cells cultured in collagen developed processes, and a few cells in every culture had long extended processes that sometimes branched and resembled those of neurons. About 60% of the cells in culture including cells with well developed processes bound the monoclonal antibody A2B5, an antibody that binds to neuronal cells in culture. Fibroblasts did not have detectable binding of A2B5. Some cells with short processes reacted with antiserum to prolactin or ACTH, but the cells with neuronlike processes did not. Collagen gels may provide a matrix in which cells from the anterior pituitary gland can differentiate into neuronlike cells.

Animals↗
PubMed1994

Optimal visualization of immunogold-silver staining of hepatic PEPCK with epipolarized light microscopy.

We used immunogold-silver staining to localize phosphoenolpyruvate carboxykinase in 10 microns cryosections of 4% paraformaldehyde perfusion-fixed normal male rat liver. The resolution and sensitivity of detection were improved by epipolarized light microscopy of 0.5 microns semi-thin plastic sections prepared from these pre-embedding immunogold-silver-enhanced 10-microns thick cryosections. Epipolarized light combined with transmitted light simultaneously demonstrated antigenic sites (visualized with epipolarized light illumination) and tissue morphology (revealed by transmitted light). To optimize the conditions for high resolution, an oil immersion objective lens (x 100) with adjustable iris diaphragm was used with different intensity settings for both light sources. Our observations indicate that if the intensity of the transmitted light is too high, the visibility of the gold-cored silver grains by epipolarized illumination is decreased; if the intensity of epipolarized light is too strong, haloes appear around the gold-cored silver particles. By adjusting the aperture in the objective lens and the neutral density filter in the transmitted light pathway to balance the intensities of transmitted and epipolarized light, an optimal image is obtained that shows the maximal number of antigenic sites and excellent morphology.

Animals↗
PubMed1983

Ultrastructure of nondecalcified supragingival and subgingival calculus.

THE ULTRASTRUCTURE of nondecalcified supragingival and subgingival calculus was studied in mature deposits. To facilitate sectioning of the embedded material, a thin reinforcing film of plastic was painted on the block. A new film was applied for each section. Light microscopy showed that supragingival calculus was heterogeneous with islets of calcified material within the covering plaque and with noncalcified areas within the calculus. Under transmission electron microscopy supragingival calculus was heterogeneous, dominated by microorganisms, small needle-shaped crystals and large ribbon-like crystals. In the covering soft plaque small crystals were often scattered in the intermicrobial matrix. In the supragingival calculus itself noncalcified microorganisms were surrounded with densely packed small crystals. There were also rosettes and bundles of large crystals. Subgingival calculus was homogeneous in light microscopy. The covering plaque contained no calcified material and only calcified material was seen within the calculus itself. Transmission electron microscopy of subgingival calculus revealed crystals of small size only. Subgingivally very few noncalcified microorganisms were seen within the calculus. The bacterial cell wall seemed to be the structure that was last calcified, both supragingivally and subgingivally.

Calcinosis↗
PubMedDate not supplied

Large block embedding and "pop-off" technique for immunoelectron microscopy.

A technique for immunoelectron microscopy is described whereby tissue is embedded in large (6 x 12 mm) plastic blocks and reembedded ("popped off") directly from semithin (3-microns) sections for thin sectioning. This technique is particularly useful in locating relatively sparse cells or tissue structures. Three acrylic plastics were evaluated: Lowicryl K4M, LR Gold, and LR White. Results indicated excellent ultrastructural morphologic preservation and retention of antigenicity with the first two plastics both comparable to conventional methods of processing. Lowicryl and LR Gold were successfully adapted to the large block pop-off technique. Technical problems were encountered with LR White.

Acrylic Resins↗
PubMed1999

Anatomical observations of the rat cerebellar nodulus after 24 hr of spaceflight.

Exposure to microgravity causes alterations in postural, locomotor and oculomotor functions. The vestibular abnormalities experienced by astronauts entail immediate reflex motor responses, including postural illusions, sensations of rotation, nystagmus, dizziness and vertigo, as well as space motion sickness. Adaptation to the microgravity environment usually occurs within one week, and a subsequent re-adaptation period of several months is often required upon return to Earth. Some astronauts experience recurrences of dizziness, nausea, and vomiting, as well as marked disturbances in postural equilibrium in the absence of vision during this readaptation period. The mechanisms underlying such adaptation processes remain unclear, although current evidence favors some type of sensory conflict. The purpose of the present study was to explore the structural basis for the reorganization in the central vestibular system that underlies the process of adaptation to altered gravitational environments. Hindbrain tissue was obtained from rats flown on the Neurolab shuttle mission (STS-90) that launched on April 17, 1998. Tissue for the present report was obtained from four adult Fisher 344 rats sacrificed on orbit during flight day 2 (FD2), 24 hr after launch. Equal numbers of vivarium control animals and cage-controls were sacrificed 48 and 96 hr, respectively, after the flight dissections. Following decapitation, each hindbrain was immersion-fixed for 45 min in 4% paraformaldehyde/0.1% glutaraldehyde in 0.1M phosphate buffer pH 7.3, and then transferred to a 4% paraformaldehyde solution in 0.1M phosphate buffer for 18 days at 4 degrees C. After this fixation, the cerebellum was dissected away from the ventral portion of the brainstem by severing the cerebellar peduncles. The entire cerebellum of each rat was cut by Vibratome into 100 micrometers thick sections in the parasagittal plane. These sections were collected serially and processed for electron microscopy by osmication, dehydration in a graded series of methanol solutions, infiltration with resin, and embedment in Epon-Araldite resin between plastic coverslips.

Adaptation, Physiological↗
PubMedDate not supplied

Subcellular localization of enzymes.

Localization of enzyme activity at the subcellular level requires techniques that have been essentially developed for the conventional light microscopic histochemistry and modified to fulfull the requirements of high resolution. Such procedures are manipulated in a certain sequence that starts with a short period of fixation, capture of the enzyme activity, postosmication and then dehydration followed by embedding of the specimen in a suitable plastic medium. References for the study of some selected enzymes pertinent to the hepatocytic organelles and their response under varied conditions are given as an example of the various procedures applied. Absence of glucose-6-phosphatase activity is currently used as a marker for the detection of early formation of preneoplastic cells in the liver of experimental animals treated with hepatocarcinogens and other agents.

Animals↗
PubMed1994

Cell loss in dimethylbenz(a)anthracene-induced rat mammary carcinoma treated with toremifene and ovariectomy.

The antiestrogen toremifene treatment results in regression or stabilization of dimethylbenz(a)anthracene(DMBA)-induced rat mammary tumors by reducing the mitotic activity and possibly by modifying the abundant spontaneous apoptosis seen in these tumors. A comparative study on the modes of cell loss was performed in untreated DMBA tumors and in tumors treated with toremifene and ovariectomy. Ovariectomy results in massive apoptotic cell death throughout the tumors with apoptotic cells exfoliating into the glandular lumina. Apoptosis accounts for most of the cell death also in the untreated tumors. The distinctly different morphology of the apoptotic cells in the untreated tumors (condensed apoptosis) and tumors treated with ovariectomy (blebbing apoptosis) may reflect the different type or schedule of the apoptotic process. Both morphologies of apoptotic cells were seen in the toremifene-treated tumors. Blebbing apoptosis is not easily examined in paraffin-embedded material but is best detectable in plastic sections and by electron microscopy.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1986

Behavior and ultrastructure of in vitro ageing mouse embryo fibroblasts grown in collagen gels.

We have compared the behaviour and the ultrastructure of embryonic mouse fibroblasts embedded into collagen gels at early, middle and late population doubling levels (PDL). Late mouse fibroblasts were able to induce gel contraction with a greater efficiency than young cells. We did not find any differences in the organization of these gels. Electron microscope observations on gels containing fibroblasts of different PDL showed that the collagen lattice induced new specific and distinct phenotypes. The well-known ultrastructural differences between young and late fibroblasts grown on plastic substrates were less prominent when these cells were embedded into collagen gels. The late fibroblasts grown into gels kept their large size and their lobulated nuclei and resembled fibroblasts grown on plastic surfaces. However, dramatic changes were observed in their pattern of microfilaments, in the dispersion of their chromatin and in their ergastoplasmic structure; these characteristics observed in late fibroblasts grown into gels were close to those of young cells. The new phenotypes of young, middle-aged and late fibroblasts in the collagen gels seemed to be stable and did not display the characteristics of an older phenotype on continued incubation. When the fibroblasts left the gel, they returned to their initial phenotype.

Actin Cytoskeleton↗
PubMed2002

Functional gliding spaces of the dorsal side of the human hand.

The clinical and functional importance of gliding spaces of the hand (e.g., their role in the spread of infection or as a consideration in reconstructive surgery) has been repeatedly emphasized. However, only a few studies have provided details regarding the connective tissue spaces in the metacarpal region of the dorsal side of the human hand. The aim of the present study was to analyze the morphology and elucidate the anatomic relation of functional gliding spaces in the metacarpal region on the dorsal side of the human hand in order to provide a better understanding of function, and of clinical disorders and their treatment. To delineate these spaces we used a plastic (Acrifix 90) injection method. Twenty fixed and unfixed cadaver hands were subcutaneously injected with Acrifix 90 (a methacrylate) into the metacarpophalangeal transitional region and into the tendon sheaths of the extensor muscles. Different colors were used to distinguish one injected plastic solution from another. The spreading pattern of the injected medium was analyzed by careful dissection. To delineate the exact bordering structures and the topography of the injected spaces, two hands were plastinated using the E12/E6 technique (von Hagens et al., Anat Embryol 1987;175:411-421), and one hand was injected and embedded in Technovit 7100 for histological investigations. Injecting the plastic into the metacarpophalangeal transitional region of fingers II-IV in a disto-proximal direction, the solution spreads along the surface of the separate extensor tendons. It then coalesces 1-2 cm proximal to the injection points to form a continuous plastic plate, which protrudes between and on top of the previous injected tendon sheaths. In no case was a communication between the paratendinous tissue and the tendon sheaths observed. Laterally, the injected solution is delimited at the radial side of the extensor tendon of the second finger and at the ulnar side of the extensor tendon of the fourth finger. Using the described technique at the fifth finger yields a plastic plate that extends from the injection point to the tendon sheath. However, in two specimens a connection between the plastic injected into the tendon sheath of the fifth finger, and the distal injected solution was observed.

Cadaver↗
PubMed1986

A simple method using alizarin red S for the detection of calcium in epoxy resin embedded tissue.

This report presents a simple procedure for staining 1-2 microns epoxy plastic sections of cells and mineralizing matrix present in fetal bovine bone tissue cultures. A 0.3% aqueous toluidine blue O solution was used as a cellular stain and was followed with 2% alizarin red S for the detection of calcium at sites of mineralization. Effects of concentration and pH of alizarin red S on the penetration of epon embedded thick sections were investigated. Optimal staining was achieved with a 2% aqueous alizarin red S solution adjusted to a pH of 5.5-6.5. This staining procedure provides unusually clear contrast between mineral and bone cells in plastic sections for light microscopy.

Animals↗
PubMed1986

The ultrasonic detection of soft tissue foreign bodies.

The ability of B-scan ultrasonography to detect soft tissue foreign bodies of various sizes and composition was investigated in a canine model. Foreign bodies consisting of wooden rods 0.7 mm and larger, lead-free glass rods 2.0 mm and larger, plastic rods 3.9 mm and 5.6 mm, and metal needles 0.5 mm and larger were embedded in fleshy soft tissue. All objects examined were discernible. Wood is best visualized followed by glass, plastic, and metal. Ultrasound may be a valuable noninvasive means of detecting soft tissue foreign bodies; further investigation to delineate its clinical role is warranted.

Animals↗
PubMed1982

The origin of lipid phagocytes in the central nervous system: II. The adventitia of blood vessels.

The source of the lipid phagocytes that occupy a cerebral infarct has been determined by light and electron microscopy in the brains of rodents and by light microscopy only in the brains of primates. The infarcts (in neocortex, hippocampus, and thalamus) were the consequence of hypoxia-ischemia of various types. Hemorrhagic infarcts were excluded. After in vivo perfusion-fixation, paraffin- and celloidin-embedded material was used for light microscopy. Semithin plastic sections from the neocortex and thalamus were studied with the light microscope and ultrastructural studies were confined to the same regions. In all animals after about 2 days there was evidence of phagocytic activity in the fibroblasts in the adventitia of the remaining large vessels and also proliferation by mitotic division. At 5-7 days fibroblasts appeared to migrate from the vessels in a semifluid or fluid milieu and to give rise to typical phagocytes. These increased in size and number but signs of degeneration became apparent after 10 days and they had largely disappeared by 32 days. Smooth muscle cells and pericytes showed evidence of degeneration and phagocytic activity was never seen in the latter.

Animals↗
PubMedDate not supplied

Surgical sutures: MR artifacts and sequence dependence.

Artifact reduction is fundamental to the daily clinical application of magnetic resonance (MR) imaging. Imaging of the postoperative patient may be difficult because of surgically introduced materials that result in artifacts. The authors tested some commonly used types of surgical suture for MR susceptibility artifact with various imaging sequences. Ten different suture types were studied. Suture was immersed in vegetable oil in separate plastic test tubes. The sutures were also studied embedded in meat. All samples were studied with T1-weighted and T2-weighted spin-echo, STIR (short-inversion-time inversion-recovery), and two-dimensional and three-dimensional gradient-echo sequences. Silk suture produced the most artifact.

Animals↗