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At least 1,567 records · Page 87Linked to original sources
PubMed2005

Improved surgical outcome by modification of porcine dermal collagen implant in abdominal wall reconstruction in rats.

AIM: We earlier showed in rats that fascial repair with Pelvicol, a porcine dermal collagen implant, was associated with a lesser inflammatory response but lower tensile strength in the early postoperative period as compared to Prolene. Herein we wanted to evaluate whether creation of pores in Pelvicol, facilitating ingrowth of fibrous tissue and vessels, would result in a higher tensile strength at d30 without compromising longer term results. METHODS: First tensile strength of Pelvicol modified with different pore sizes was evaluated ex vivo. In a second step, Pelvicol implants with pores were used to cover full-thickness abdominal wall defects in 36 rats. Implants were either Pelvicol (non-porous) or with pores of Phi : 0.7, 1.2, or 2.0 mm (n=6 each). Animals were sacrificed on d30 and 90 to evaluate the presence of herniation, infection, adhesions, change in thickness and tensile strength. Histopathology was performed to assess inflammatory response and collagen deposition. Data were compared to available data on Prolene implanted animals at same time points. RESULTS: Pelvicol with pore diameter of 2.5 mm was significantly weaker ex vivo. Animals repaired with non-porous material did develop seroma (2/6) or clinical infection (1/6) whereas none in the other groups did. There was a trend for increasing tensile strength at 30 d with increasing pore diameter, being significant in the 2.0-mm pore size group. This difference disappeared by 90 d, where all materials were equally strong as Prolene. The foreign body reaction was less intense in a pore-size dependent manner, with more abundant neo-vascularization and collagen deposition passing through the pores. CONCLUSION: Creation of pores in Pelvicol promotes neo-vascularization, collagen deposition, and fibrous tissue ingrowth, and at pore size 2.0 mm tensile strength was increased at d30 whereafter all materials had comparable strength.

Abdominal Wall↗
PubMed1990

A standardized method for determination of crown margin fidelity.

Previous research on crown margin fidelity is reviewed and methods of measurement are compared and scrutinized. A standardized method for the determination of crown margin fidelity is introduced. A biologically oriented rationale is presented for analysis of the measurement parameters. This system places a strong emphasis on measuring factors that impact upon accumulation of plaque and the microbiologic environment around crowns, ultimately affecting gingival health. Crown samples were cemented on master dies and were embedded for sectioning buccolingually and mesiodistally. Photographs of margins with plastic overlays indicating emergence profiles were used to determine vertical and horizontal marginal discrepancies. Three observers measured seven crown systems for the vertical and horizontal marginal discrepancies of each crown system. The interobserver variance was 10 microns for the horizontal and 9 microns for the vertical marginal discrepancy.

Calibration↗
PubMed2003

Monoclonal antibodies to denatured human ACE (CD 143), broad species specificity, reactivity on paraffin sections, and detection of subtle conformational changes in the C-terminal domain of ACE.

Two new mouse monoclonal antibodies (mAbs) were generated to denatured human angiotensin-converting enzyme (ACE, CD143). The clones 2E2 and 3C5, each of the IgG1 kappa chain isotype, detect ACE with high sensitivity, respectively, at 20 ng and 2 ng of protein per lane in Western blotting. They both recognize different epitopes on the C-domain of ACE located between amino acid residues 740 and 992. In formalin-fixed and paraffin-embedded human tissues, immunohistochemistry revealed all known expression sites of ACE, e.g. the epithelial brush borders of proximal kidney tubules, epithelial cells of epididymis, endothelial cells, activated macrophages as well as germ cells during spermatogenesis. In contrast to other mAbs to denatured human ACE, mAbs 2E2 and 3C5 demonstrate cross-reactivity with a broad spectrum of animal species such as monkey, rat, rabbit, cattle, dog, cat, and guinea pig. In addition, mAb 2E2 recognized mouse ACE in Western blotting and on paraffin sections. Our findings suggest that mAbs 2E2 and 3C5 are useful for identifying even subtle changes in ACE conformation resulting from denaturation. These mAbs are also sensitive tools for the detection of minimal amounts of ACE in biological fluids and tissues using proteomics approaches. Their reactivity in routinely processed tissues of various species may prove useful for correlation of ACE expression in animal models to human diseases.

Amino Acid Sequence↗
PubMed1985

Ultrastructure of acute ammonia toxicity in the human lung.

A tanker truck carrying anhydrous ammonia (NH3) fell off a freeway, releasing a dense cloud of NH3 gas, killing several people. The driver was dead upon impact. To our knowledge, pulmonary NH3 toxicity in humans has not been studied previously by electron microscopy (EM). Therefore, in two cases, the paraffin-embedded tissue blocks of lung were deparaffinized and reembedded in plastic for 1-mu sections and EM examination. The lung tissue of a third case, the truck driver, was similarly processed as a control. Light-microscopic pulmonary findings in the acute NH3 deaths included denudation of the tracheobronchial epithelium, edema of the lamina propria, and marked alveolar edema, congestion, and hemorrhage. In contrast, in the truck driver's lungs, the bronchial epithelium was intact, and there was no gross odor of NH3. Massive pulmonary hemorrhages in his lungs were attributed to trauma rather than NH3 inhalation. EM examination of the lungs of the truck driver showed no discernible toxic alterations in either the capillary endothelial cells or the Type I or II alveolar epithelial cells, and alveolar and capillary basement membranes were intact. In contrast, EM study of the lungs from two individuals dying acutely of NH3 inhalation showed marked swelling and imbitional edema of Type I alveolar epithelial cells; however, alveolar basement membranes and capillary endothelial cells appeared as usual. These electron-microscopic findings demonstrate the Type I epithelial cell to be the target cell of acute alveolar wall injury in NH3 inhalation.

Adult↗
PubMed2007

Negative pressure dressing for promoting wound healing of purpura fulminans in a newborn with homozygous protein C deficiency.

A negative pressure dressing to promote wound healing of purpura fulminans in a girl aged 35 days with homozygous protein C deficiency is reported. Two wounds of 11 x 11 cm2 at the abdominal wall and 14 x 14 cm2 at the left trunk were covered with sterile sponges embedded with a multiple-hole drain tube and transparent plastic film. The exposed end of the drain was then connected to the wall suction apparatus to create negative pressure at -120 mmHg. The dressing was changed every 2 days. Within 4-6 weeks, the wounds were completely healed and skin grafting was not required.

Abdominal Injuries↗
PubMed1985

Human monoclonal anti-MAG antibody and anti-Leu 7 recognise shared antigenic determinants in peripheral nerve and spinal cord.

Anti-Leu 7 monoclonal antibody (MAB), a marker of natural killer cells, and a human MAB to myelin-associated glycoprotein (MAG) from a patient with a demyelinating neuropathy specifically stained Schmidt-Lanterman incisures, paranodal and periaxonal regions in peripheral nerve myelin by immunocytochemistry on thin plastic sections, while compact myelin was labelled in paraffin-embedded material. Preabsorption studies indicated that the antigen recognised was a MAG epitope shared by MAG and Leu 7. In spinal cord both MABS bound to oligodendrocytes and a subclass of anterior horn cells. Our findings support the hypothesis that shared antigens between the nervous and the immune systems do exist in situ, which may be important in the pathogenesis of demyelinating neuropathies with monoclonal gammopathies.

Animals↗
PubMedDate not supplied

Comparison of expression of cathepsins B and L and MMP2 in endothelial cells and in capillary sprouting in collagen gel.

The lysosomal cysteine proteinases cathepsins B and L are known to play an important role in the invasive growth of tumor cells, but their association with angiogenesis has been less well studied. The aim of this study was to determine the possible role of endothelial cell-associated cathepsins B and L in induced capillary growth in the aorta ring model of angiogenesis. Specific inhibitors of cysteine proteinases did not inhibit capillary growth in aorta ring culture and only slightly inhibited the degradation of surrounding collagen. In contrast, strong inhibition of both processes by the matrix metalloproteinase inhibitor BB-94 was observed, indicating the importance of endogenous MMP production in angiogenesis. In support of this finding, we demonstrated a significant increase in endogenous endothelial mRNA of MMP2, but not of cathepsins B and L, in proliferating primary human dermal microvascular endothelial cells (HMVEC-d) in culture. However, MMP2 mRNA expression was increased only when the cells were embedded in collagen but not when they were grown on plastic, regardless of the addition of the growth factors VEGF or bFGF. Moreover, on plastic the impairment of MMP2 induction by growth factors was observed. The differential effect of growth factors implies the crosstalk with integrin signaling as a consequence of binding to the different matrix. This study suggests that endothelial cell-associated cathepsins B and L are not involved in the invasive growth of capillaries from existing blood vessels and that the presence of collagen is necessary for MMP2 expression in endothelial cells.

Animals↗
PubMed1988

[Immuno- and enzymehistochemical studies of methacrylate-embedded biopsy material, especially iliac crest biopsies].

Immunohistochemical and histochemical methods are increasingly used and their application in surgical pathology is obvious. Especially we used these methods on bone marrow core biopsies. Optimal and comparable results have been obtained by using different methods after halving the biopsy cores longitudinally and/or transversally. The two halves were used for cytologic imprints. Two parts of the biopsy cores were embedded in polymethacrylate at low temperature (-20 degrees C). The methacrylate-embedded biopsy part for routine histology was fixed in Schaffer's solution (methanol-formalin-fixative). The methacrylate-embedded undecalcified section of 4 microns may be stained by most stains commonly employed in routine histopathology after removal of the plastic. The sections are virtually free of artefacts such as shrinkage and swelling in the light microscope. The second methacrylate-embedded part of biopsy cores was fixed in 2% paraformaldehyde with 5% sucrose in 0.02 M phosphate buffer (pH 7.4) and dehydrated in ethyleneglycolmonobutylether. All procedures were carried out at 4 degrees C. This method permits the use of immunohistochemical and histochemical procedures. The immunohistochemistry was carried out at sections of 4 microns after removal of the plastic with methoxide and use of proteolytic enzyme (0.1% alpha-chymotrypsin) to unmask antigens in sections. Surface and intracellular immunoglobulins were very well detected with the indirect FITC method. The histochemical procedures are carried out at sections of 7-8 microns after removal of plastic with xylene and toluol. The sections were incubated for specific esterase and nonspecific esterases, acid and alkaline phosphatase and then examined by light microscopy. A third part of biopsy cores may be immediately frozen, and cryostat sections are stained and evaluated for rapid diagnosis and used for immunohistologic analysis with mono- and polyclonal antibodies (FITC method) and/or histochemical investigations. Imprints of biopsy cores are evaluated for cytological, cytochemical and/or immunocytological analysis with mono- and polyclonal antibodies (FITC method). The cryostat sections and the imprints are fixed for all methods with 2% paraformaldehyde and 5% sucrose in PBS (0.02 M, pH 7.4) at 4 degrees C for 30 minutes. The best diagnostic results were obtained in the myelo- and lymphoproliferative disorders using the combination of methods described here. Examples were demonstrated.

Biopsy↗
PubMed1990

Ultrastructural immunogold labeling of glial filaments in osmicated and unosmicated epoxy-embedded tissue.

On-grid (post-embedding) immunolabeling methods with epoxy resins have been difficult to apply to thin structures such as intermediate filaments, which may remain inaccessible within the plastic. In this study, glial fibrillary acidic protein (GFAP), the major protein of astrocyte intermediate filaments, was localized with a post-embedding immunogold method, using both unosmicated and osmicated material embedded in epoxy resin. The tissue studied was from a diagnostic brain biopsy on a child with Alexander's disease. This disorder is characterized by proliferation of astrocyte intermediate filaments and formation of Rosenthal fibers. With unosmicated tissue, as in a previous study, extensive labeling of the glial filaments was achieved only when ultra-thin sections were pre-treated with dilute sodium ethoxide, an agent that dissolves plastic. Fifteen-nm gold could be used. With osmicated tissue, localization to glial filaments required pre-treatment with sodium ethoxide and with the oxidizing agent sodium metaperiodate, followed by the use of small (5 nm) colloidal gold. That 5-nm gold was required for labeling filaments in osmicated material suggested that osmication increases problems of penetrability and antigen accessibility within ultra-thin sections. The large Rosenthal fibers were labeled by 15-nm gold in both unosmicated and osmicated material. The methods employed may be useful for electron immunolocalizations to other thin structures in material embedded in epoxy resin.

Astrocytes↗
PubMed1996

Effect of specimen fixation method on pullout tests of pedicle screws.

STUDY DESIGN: Experimental axial pullout tests of a new type of pedicle screw were done on cadaveric lumbar vertebrae. The manner in which specimens were secured in the testing apparatus was varied to determined influence of specimen fixation method on the maximum pedicle screw pullout force. OBJECTIVES: To determine the appropriateness of embedding (i.e., potting) spinal specimens in polymer resin (e.g., bone cement or Plastic Padding [Plastic Padding Ltd., High Wycombe, Buckinghamshire, England]) for axial pullout tests of pedicle screws. Several different specimen fixation methods were examined to make recommendations for the standardization of future experimental testing protocols. SUMMARY OF BACKGROUND DATA: Axial pullout of transpedicular screws, although not a likely clinical mode of failure, is a popular experimental testing mode for evaluating screw-bone biomechanics. A wide variety of techniques for securing a vertebral specimen to counter the axial pullout force has been reported (including the use of polymer resin) with a correspondingly wide range in the resulting axial pullout strengths. The possible influence of the specimen fixation method on pedicle screw axial pullout strength has not been addressed previously. METHODS: Axial pullout tests of pedicle screws (DDS, Plus Endoprothetik, Rotkreuz, Switzerland) from the pedicles of 21 isolated lumber vertebral bodies were done using a Model 810 MTS Universal Testing Machine (MTS Systems, Inc., Minneapolis, Minnesota). The specimens were secured in a custom-made vise fixture either as is or after the vertebral bodies were potted in Plastic Padding up to the pedicle origin. Some of the potted specimens were wrapped first in latex to prevent polymer resin intrusion, and the others were unprotected. Pullout tests were attempted on both the left and right pedicles of each specimen, and the maximum pedicle screw pullout force was recorded. Measurement of bone mineral density by means of dual energy x-ray absorptiometry, in addition to macroscopic and scanning electron microscopy histologic analyses, microradiography, and energy dispersive X-ray spectroscopy, was done post-test to assist in the interpretation of the data. RESULTS: The maximum pedicle screw pullout force was found to be dependent on both the bone mineral density and the mode of fixation of the vertebrae. Embedding in polymer resin without protection of the specimen (i.e., latex wrapping) led to several instances of well-documented polymer resin intrusion; in these specimens, mean maximum pedicle screw pullout force was significantly greater than that of specimens secured without polymer resin and that of embedded specimens for which intrusion did not occur. CONCLUSIONS: Polymer resin intrusion can have a significant effect on the biomechanical characteristics of the bone-pedicle screw interface. When polymer resins are used to secure vertebral specimens for in vitro biomechanical tests of the bone-pedicle screw interface, it is important to either prevent intrusion (e.g., with a latex wrapping) or document post-test (e.g., through the methods described in this article) that intrusion did not occur for the specimens included in the analysis.

Aged↗
PubMed1984

The application of cobalt labelling to electron microscopic investigations of serial sections.

The cobalt labelling technique can be applied to ultrathin serial sections and subsequent electron microscopical investigations with the following modifications: a prolonged, up to 12 h, fixation of the tissue in aldehydes; a shortened, 15 min, postfixation in OsO4; embedding in soft resin block by using a higher proportion of plasticizer in the polimerizing mixture; mounting of 5 micrometers thick serial sections between two layers of Agar-Agar coatings; performing the intensification of the Agar section-Agar sandwich with a physical developer containing a low percentage of the reductive agent; reembedding selected thick sections for ultrathin serial sectioning and staining with uranile acetate and lead citrate. The technique unambiguously shows all labelled profiles, and preserves the fine structural details of the surrounding tissues.

Animals↗
PubMed1982

Properties of organic specimens and their supports at 4 K under irradiation in an electron microscope.

Radiation damage is one of the most severe problems in the electron microscopy of organic materials. Observations which were made in an electron microscope with a superconducting lens system have shown that the damage caused by the electron beam is considerably reduced by one to two orders of magnitude if the specimen is cooled to liquid helium temperature (4.2 K). This cryoprotection is even higher in favorable cases, particularly when embedded specimens are used. The cryoprotection decreases for specimens mounted on plastic carrier films due to the low thermal and electrical conductivity of these materials at low temperatures.

Amino Acids↗
PubMed2003

A new method for preparing powders for transmission electron microscopy examination.

In this paper we describe a novel method to prepare powder specimens for transmission electron microscopy examination. The powder samples are embedded in a metallic matrix by a route based on the plastic flow of a soft metal, using a small laboratory type hand driven hydraulic press. The resulting composites are processed with the conventional procedure based on grinding polishing and ion beam milling. The resulting TEM specimens have a self-supporting structure, good thermal and electrical conductivity while showing a well-polished surface resulting from the ion milling process. The method can be applied to a large variety of samples with sufficiently strong mechanical properties; a few examples are reported. The limits, mainly due to the mechanical toughness of the powder, are discussed.

Copper↗
PubMed1980

A method for processing paraffin sections of multilayer cultured tissue.

A simple and rapid method is described for processing histological preparations from multilayer cultures growing in plastic Petri dishes, A covering collodion film is utilized to remove the tissue from the plastic dish and transfer it onto a paper block prior to embedding in Paraplast. To avoid any disruption by the collodion of the plasticware, the cultured tissue is first immersed in a solution of collodion and absolute alcohol (1:1) and then covered with pure collodion. All steps are carried out in the cold. This procedure allows morphological, histochemical, immunofluorescent, and autoradiographic studies to be carried out on serial sections of cultured tissue.

Animals↗
PubMed2006

Lipid signaling and synaptic plasticity.

Lipids are essential components of plasma- and organelle-membranes, not only providing a frame for embedded proteins (e.g., receptors and ion channels) but also functioning as reservoirs for lipid mediators. Increasing evidence indicates that bioactive lipids such as eicosanoids, endocannabinoids, and lysophospholipids serve as intercellular and intracellular signaling molecules participating in physiological and pathological functions in the brain. The discovery of some of these lipid receptors and novel lipid signaling mediators has sparked an intense interest in lipidomic neurobiology research. Classic prostaglandins (PGD(2), PGE(2), PGF(2alpha), PGI(2), and TXA(2)), catalyzed by cyclooxygenases (COX), are synthesized from arachidonic acid (AA). Experimental studies demonstrate that prostaglandin E(2) (PGE(2)), mainly derived from the COX-2 reaction, is an important mediator, acting as a retrograde messenger via a presynaptic PGE(2) subtype 2 receptor (EP(2)) in modulation of synaptic events. Novel prostaglandins (prostaglandin glycerol esters and prostaglandin ethanolamides) are COX-2 oxidative metabolites of endogenous cannabinoids (2-arachidonyl glycerol and arachidonyl ethanolamide). Recent evidence suggests that these new types of prostaglandins are likely novel signaling mediators involved in synaptic transmission and plasticity. This means that COX- 2 plays a central role in metabolisms of AA and endocannabinoids (eCBs) and productions of AA- and eCB- derived prostaglandins. Thus, in the present review article, the authors will mainly discuss COX-2 regulation of prostaglandin signaling in modulation of hippocampal synaptic transmission and plasticity.

Animals↗
PubMed1997

Head injuries in children from plastic hairbeads.

BACKGROUND: Plastic hairbeads are often worn as decorative hair fasteners by children. Serious, penetrating head injuries may result from their use and have been observed in some children following a fall. OBJECTIVE: The objective of this report is to describe the imaging findings in children who have sustained head injury while wearing plastic hairbeads. MATERIALS AND METHODS: Three children with significant head injuries resulting from embedded hairbeads are described. Three additional cases of minor head injury reported to the Consumer Product Safety Commission are summarized. RESULTS: One child sustained a minimally depressed skull fracture without brain injury. The second child required surgical repair of a depressed skull fracture complicated by a parenchymal hemorrhage and dural tear. A third child required surgical evacuation of an organized, liquefied epidural hematoma 2 weeks after an initial evaluation at an outside emergency room. CONCLUSION: Children wearing plastic hairbeads are at risk for severe head injury following a fall. Caution must accompany their use.

Brain Injuries↗
PubMed1997

Sample preparation from paraffin-embedded tissue specimens for laser scanning cytometric DNA analysis.

We have developed a simple, rapid method for isolating cells from a block of formalin-fixed, paraffin-embedded tissue specimen for laser scanning cytometric (LSC) DNA analysis by using a grater. The scraping-like tissue samples were obtained by grating a paraffin-embedded tissue block. The grated samples were collected, put into a small plastic tube, and deparaffinized with xylene. Subsequently, the samples were immersed in 100% ethanol to remove the xylene. After using a syringe with a 26-gauge needle and filtering through 40-microm nylon mesh, the cells suspended in ethanol were dropped directly onto a glass slide. As a result, isolated cells adhered tightly to the glass slide. The slides mounted with isolated cells were treated with 0.1% pepsin in 0.1 N HCl for 1 h at 37 degrees C and then 0.1% RNase for 10 min at room temperature. The slides were dipped in propidium iodide (25 microg/ml) to stain DNA and sealed with nail varnish. The coefficients of variation for histograms were small enough to detect an aneuploid peak close to the diploid peak.

Aneuploidy↗