Mandibular replacements--a review of embedded implants.
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Adolescent↗
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Embedding media for 1-2 micron sectioning. 3. Hydroxyethyl methacrylate-benzoyl peroxide activated with pyridine.
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Acrylates↗
A novel method for freezing and storing research tissue bank specimens.
Preserving small pieces of frozen tissue for possible future ancillary studies ("tumor banking") usually involves either placing a small piece of tissue in a cryovial and snap freezing it in liquid nitrogen or embedding and freezing the tissue in a block of cryopreservation medium, such as optimal cutting temperature (OCT) compound. The cryovial storage method leaves an irregularly shaped piece of tissue frozen to the side of the plastic vial, where it is exposed to air, subject to desiccation ("freezer burn"), and difficult to remove, but the vials are easy to store. The OCT method results in good morphological preservation, but yields a large awkwardly stored block from which it may be difficult to locate and recover small specimens. We have proposed a novel method of storing tissue bank specimens, the "capsule-freeze" method, which combines the advantages of OCT specimen preservation with those of cryovial specimen storage. Using this method, a tissue specimen is "snap-frozen" in OCT within a size "00" VCap pharmaceutical capsule, then the capsule is stored within a 1.5-mL cryovial. The specimen is harvested by simply cutting a slice out of the capsule and sealing the cut ends with OCT before their return to the freezer. The slice is then embedded en face within an OCT block before frozen sectioning. Morphological preservation is excellent, and the capsules are very easy to store. Occasional cracking that we found with the use of gelatin capsules is greatly diminished with the use of VCaps cellulose-walled capsules. The OCT can be easily removed by rinsing in cold 70% ethanol solutions. This method of tissue storage is ideal for the small specimens that are now commonly archived in these days of tissue sparing surgery.
Capsules↗
Establishment and characterization of a new human prostatic carcinoma cell line (DuPro-1).
A new human prostate adenocarcinoma cell line (DuPro-1) has been established from the athymic nude mouse supported xenograft DU5683. This was accomplished by embedding dispersed xenograft cells in 0.1 by 5.0 cm. spaghetti-like strands of Basement Membrane MATRIGEL [BMM (Collaborative Research, Inc.)], a unique technique facilitating the transition to tissue culture. Now passed over 30 times, the cells display anchorage and serum concentration independent growth with a doubling time of 22 to 24 hours. Cells exhibit pronounced morphological differences when grown on BMM coated culture dishes, assuming a pseudoglandular configuration, in contrast to typical homogeneous monolayer growth on plastic culture dishes. Light and electron microscopy show cohesive sheets of anaplastic epithelial cells, consistent with prostate carcinoma. Karyotypic analysis revealed all human chromosomes, near tetraploidy, 10 to 12 markers, and 3 to 4 X chromosomes, without a Y chromosome. Cells injected s.c. or embedded in BMM and implanted in the subrenal capsule space are equally tumorigenic in male and female athymic mice, suggesting that DuPro-1 cells are hormonally insensitive. Embedding cells in BMM may be useful in developing other tissue culture cell lines from neoplasms difficult to initiate in vitro. DuPro-1 should provide a valuable means to study the biology, immunology, and chemosensitivity of human prostate cancer.
Adenocarcinoma↗
Structural plasticity of the cyclic-cystine-knot framework: implications for biological activity and drug design.
The cyclotide family of plant proteins is of interest because of their unique topology, which combines a head-to-tail cyclic backbone with an embedded cystine knot, and because their remarkable chemical and biological properties make them ideal candidates as grafting templates for biologically active peptide epitopes. The present study describes the first steps towards exploiting the cyclotide framework by synthesizing and structurally characterizing two grafted analogues of the cyclotide kalata B1. The modified peptides have polar or charged residues substituted for residues that form part of a surface-exposed hydrophobic patch that plays a significant role in the folding and biological activity of kalata B1. Both analogues retain the native cyclotide fold, but lack the undesired haemolytic activity of their parent molecule, kalata B1. This finding confirms the tolerance of the cyclotide framework to residue substitutions and opens up possibilities for the substitution of biologically active peptide epitopes into the framework.
Amino Acid Sequence↗
The thin-film adsorber hemoperfusion device: detailed mass transfer and flow characteristics.
Further testing and evaluation of the thin-film adsorber (TFA) type of hemoperfusion device is reported here to complement an earlier paper describing the development of these devices and clearance tests performed with them. The present paper describes the results of pressure drop tests, flow uniformity tests, and detailed studies of the mass transfer characteristics of the components of the TFA units. The TFA units consist of powdered activated charcoal embedded in thin films of cellulose nitrate. These films are sprinkled with small particles of granular charcoal and then wound into spools, which are then placed in a plastic housing. The use of powdered charcoal exploits the enormous rate-of-uptake advantage of powdered charcoal over the granular sorbents used in other hemoperfusion devices. The present tests showed that the pressure drops in the TFA devices are intrinsically low, but that their priming volumes are only marginally acceptable. Significant flow nonuniformities also exist. Despite this, the overall mass transfer resistance values for the TFA devices are lower than those for available commercial hemoperfusion units. Measurements of diffusion coefficients in the carbon and in the carbon-loaded polymer film showed that in the carbon-loaded film, the slowest diffusion step involves the carbon particles themselves. Other tests disclosed that the liquid external to the film (i.e., in the flow spaces) offers even greater mass transfer resistance than does the carbon-loaded film. Further evaluations of the TFA type of device are suggested, particularly concerning its thrombogenic properties.
Adsorption↗
Perceptual learning directs auditory cortical map reorganization through top-down influences.
The primary sensory cortex is positioned at a confluence of bottom-up dedicated sensory inputs and top-down inputs related to higher-order sensory features, attentional state, and behavioral reinforcement. We tested whether topographic map plasticity in the adult primary auditory cortex and a secondary auditory area, the suprarhinal auditory field, was controlled by the statistics of bottom-up sensory inputs or by top-down task-dependent influences. Rats were trained to attend to independent parameters, either frequency or intensity, within an identical set of auditory stimuli, allowing us to vary task demands while holding the bottom-up sensory inputs constant. We observed a clear double-dissociation in map plasticity in both cortical fields. Rats trained to attend to frequency cues exhibited an expanded representation of the target frequency range within the tonotopic map but no change in sound intensity encoding compared with controls. Rats trained to attend to intensity cues expressed an increased proportion of nonmonotonic intensity response profiles preferentially tuned to the target intensity range but no change in tonotopic map organization relative to controls. The degree of topographic map plasticity within the task-relevant stimulus dimension was correlated with the degree of perceptual learning for rats in both tasks. These data suggest that enduring receptive field plasticity in the adult auditory cortex may be shaped by task-specific top-down inputs that interact with bottom-up sensory inputs and reinforcement-based neuromodulator release. Top-down inputs might confer the selectivity necessary to modify a single feature representation without affecting other spatially organized feature representations embedded within the same neural circuitry.
Acoustic Stimulation↗
[Fusion implants of carbon fiber reinforced plastic].
Carbon fiber reinforced plastics (CFRP) are used in the medical field when high mechanical strength, innovative design, and radiolucency (see spinal fusion implants) are needed. During the manufacturing process of the material CFRP carbon fibers are embedded into a resin matrix. This resin material could be thermoset (e.g., epoxy resin EPN/DDS) or thermoplastic (e.g., PEAK). CFRP is biocompatible, radiolucent, and has higher mechanical capabilities compared to other implant materials. This publication demonstrates the manufacturing process of fusion implants made of a thermoset matrix system using a fiber winding process. The material has been used clinically since 1994 for fusion implants of the cervical and lumbar spine. The results of the fusion systems CORNERSTONE-SR C (cervical) and UNION (lumbar) showed no implant-related complications. New implant systems made of this CFRP material are under investigation and are presented.
Adult↗
Morphological and cytochemical study of Chlamydia with EDTA regressive technique and Gautier staining in ultrathin frozen sections of infected cell cultures: a comparison with embedded material.
The cryo-ultramicrotomy technique was applied to study the ultrastructure of Chlamydia using two strains: one of C. psittaci and one of C. trachomatis. It clearly appeared that in both strains reticulate bodies show a high degree of plasticity, contrasting with the rigid spherical appearance of elementary bodies. Ultrastructural cytochemical study shows DNA fibrils dispersed throughout the cytoplasm in reticulate bodies whereas DNA is condensed in a nucleoid in elementary and intermediate bodies. The EDTA regressive technique reveals ribonucleoproteins in reticulate and elementary bodies of both studied strains.
Animals↗
Stereo high-voltage electron microscopy of whole cells of the human diploid line, WI-38.
The human diploid cell line, WI-38, has proven to be an especially good object for high-voltage electron microscopy using whole cells. Cells of intermediate passages were grown on plastic-coated, carbon-shadowed gold grids, fixed with glutaraldehyde, post-fixed with osmium tetroxide, stained with uranyl salts and critical-point dried. The absence of an embedding matrix produces images of increased contrast and resolution. The approach combined with stereo-microscopy has extended our knowledge of cellular ultrastructure. Stereo-images of whole cells reveal nuclei, mitochondria, microtubules, microfilaments, the endoplasmic reticulum and ribosomes in their expected forms. At high magnifications a continuity of microtubules, microfilaments and membranous elements with thin (3-6 nm) strands of the ground substance has been observed. These strands form a three-dimensional lattice or mesh that pervades all parts of the cytoplasm. The entire structure is referred to as a microtrabecular lattice or mesh, the strands being the trabeculae. The inclusion of microtubules, microfilaments, ribosomes and vesicles of the endoplasmic reticulum within the material of the lattice makes them all part of a totally organized cytoplast.
Cell Line↗
A cerebellar model for predictive motor control tested in a brain-based device.
The cerebellum is known to be critical for accurate adaptive control and motor learning. We propose here a mechanism by which the cerebellum may replace reflex control with predictive control. This mechanism is embedded in a learning rule (the delayed eligibility trace rule) in which synapses onto a Purkinje cell or onto a cell in the deep cerebellar nuclei become eligible for plasticity only after a fixed delay from the onset of suprathreshold presynaptic activity. To investigate the proposal that the cerebellum is a general-purpose predictive controller guided by a delayed eligibility trace rule, a computer model based on the anatomy and dynamics of the cerebellum was constructed. It contained components simulating cerebellar cortex and deep cerebellar nuclei, and it received input from a middle temporal visual area and the inferior olive. The model was incorporated in a real-world brain-based device (BBD) built on a Segway robotic platform that learned to traverse curved paths. The BBD learned which visual motion cues predicted impending collisions and used this experience to avoid path boundaries. During learning, the BBD adapted its velocity and turning rate to successfully traverse various curved paths. By examining neuronal activity and synaptic changes during this behavior, we found that the cerebellar circuit selectively responded to motion cues in specific receptive fields of simulated middle temporal visual areas. The system described here prompts several hypotheses about the relationship between perception and motor control and may be useful in the development of general-purpose motor learning systems for machines.
Cerebellum↗
Neurotropic malignant melanoma: a novel treatment approach combining modified microscopically controlled surgery and S100 immunohistochemical staining.
Treatment of neurotropic malignant melanoma of the nasal ala combining microscopically controlled surgery and examination of formalin-fixed paraffin-embedded tissue cut in the horizontal plane followed by S100 immunohistochemical staining is described. The spindle-shaped cells were strongly S100 positive and detection of the melanoma cells, which were embedded in a dense collagenous stroma and infiltrating into the neurovascular spaces, was greatly accentuated by the S100 immunohistochemical stain. The coordinated skills of the dermatologic surgeon, dermatopathologist, and plastic surgeon contributed toward the best treatment for neurotropic melanoma in this patient.
Combined Modality Therapy↗
Methods for improved light microscope microtomy.
Experiments undertaken to improve the ease and quality of preparing tissue for light microscopy have resulted in methods for routine production of high quality serial paraffin and glycol methacrylate sections in the 1 to 4 micrometer range using a standard rotary microtome. These methods involve sectioning with mechanically-broken Ralph-type knives, inspected for quality before mounting with double-stick tape on a holder-fluid trough in which the ribbon floats over an immersed slide and sections are mounted by lowering the fluid level in the trough. Specimen return stroke retraction, necessary for quality sectioning of plastic or with a fluid trough, is inexpensively provided by an attachable specimen holder that fits into the rotary microtome's chuck and, actuated by the microtome mechanisms, retracts the specimen during each return stroke. Descriptions of four instruments: a mechanical breaker for Ralph knives, a knife edge inspection device, an attachable specimen retractor for rotary microtomes, and a section collecting-mounting device as well as details of their use are included. Differences in cutting speed and cutting cycle cadence critical to quality sectioning with different embedments are detailed. Factors important in choosing the best embedment and most appropriate section thickness as well as choosing between dry or wet sectioning methods are also considered.
Fixatives↗
Electrophysiologic study of rabbit proximal tubular cell monolayers in primary culture.
Primary cultures of renal cortical cells prepared by selective sieves have been found to display some characteristics of renal proximal tubular epithelium but their site of origin has not been confirmed by electrophysiologic studies. Cells were cultured in a defined medium on collagen gels. Confluency was approached after 7-10 days but gels were found to have zero transepithelial resistance unless they were allowed to contract spontaneously. With the appearance of a nonzero resistance, there was a change in morphology to a more columnar cell with better developed microvilli. These structural features were particularly prominent in clusters of proliferating cells observed on and around remnants of original tubules embedded in the gel. In noncontracted cultures there was no focal cell clustering and cells were squamous-like with rudimentary microvilli, similar in appearance to cells grown on plastic culture dishes. Measurements made in contracted monolayers yielded an average transepithelial resistance of 6.5 omega cm2, a spontaneous transepithelial potential difference of +0.9 mV, measured with respect to the serosa, and an apical membrane potential of -75 mV when cells were bathed in 0.4 mM K and -49 mV when cells were bathed in 4 mM K media. Mucosal protamine (50 micrograms/ml) increased transepithelial resistance by 22%, suggesting that the epithelial cell tight junctions were responsive to external stimuli. Monolayers were anion selective, giving a dilution potential (lumen-directed NaCl gradient) of -2.6 mV with respect to the serosa. These experiments show that primary culture of rabbit renal cortical cells separated by differential sieves displays electrophysiologic and morphologic characteristics of a proximal renal tubular epithelium. Confluency and attainment of differentiated morphology and function are promoted when monolayer cells are not bound to an unyielding substrate.
Animals↗
[Pathogenesis of staphylococcal infections of implanted plastics and intravascular catheters].
Coagulase-negative staphylococci are the predominant organisms causing infection of intravasal catheters and implanted plastic material. They are able to adhere to and grow on polymer surfaces. During the course of colonization they produce large amounts of an extracellular slime substance by which they are finally covered completely. It is supposed that this matrix of slime protects the embedded staphylococci against antibacterial substances and natural host defenses. The slime substance is not a true capsule but is loosely bound to the staphylococcal cells. It seems to have interesting biological properties such as an adhesin-like function and the ability to inhibit the lymphoproliferative response of mononuclear cells.
Animals↗
Detection of mammosomatotroph cells and identification of the coexistence of growth hormone and prolactin within the same secretory granules in these cells using confocal laser scanning microscopy.
This study was designed to examine whether mammosomatotroph cells (MS cells) can be easily detected using confocal laser scanning microscopy (CLSM) and whether the coexistence of growth hormone (GH) and prolactin (PRL) within the same secretory granule can be identified in the MS cell using CLSM. Conventional epoxy resin-embedded tissues of mixed GH- and PRL-secreting human pituitary adenomas were used for this double-labelling immunofluorescent study by CLSM. A semithin section of the tissue after plastic removal and bleaching was immunohistochemically double-stained with primary antibodies against GH and PRL, followed by secondary antibodies conjugated with Rhodamine (GH) and FITC (PRL). MS cells simultaneously showing fluorescence of both Rhodamine and FITC were easily detected by CLSM at lower magnification. At higher magnification, the coexistence of Rhodamine and FITC on the same secretory granule was identified by using a superimposed display. This finding was confirmed by immunoelectron microscopy. The CLSM technique may be useful for the study of MS cells.
Adenoma↗
[Application of the method of thin sections embedded in epon to corneal histology].
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Animals↗
Precast matrices for rapid embedding and orientation of large numbers of specimens in cryostat sectioning.
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Freezing↗