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PubMedDate not supplied

Microradiographic study of retrieved craniofacial osseointegrated implants.

In this study 18 screw-shaped extraoral osseointegrated implants retrieved from 10 patients were analyzed. The reasons for retrieval were: unexplained pain (n = 4); inability to cope with the implants (n = 2); fracture of the central screw (n = 2); skin penetration problems (n = 1), and trauma (n = 1). Retrieved implants were trephined with a border of surrounding bone, fixed, embedded in epon plastic, ground and processed for microradiography. The study group comprised 6 males and 4 females with a mean age of 53.4 (range 9-81) years. All implants were clinically stable at the time of removal, and the mean osseointegration time was 3 (range 1-5) years. Six implants were removed from the temporal bone, 5 from the frontal bone, and 7 from the maxilla. By microradiography, it was found that all retrieved implants were surrounded by a lamellar type of bone with haversian systems, vascular channels, osteocyte lacunae, and in some specimens regeneration and resorption areas. Bone metal contact was estimated to vary between 27 and 83%. Bone metal contact was lower in the frontal bone compared to the temporal bone or maxilla, and was further reduced after preoperative irradiation. Longer osseointegration time increased bone metal contact, as did increased age up to 60 years. It is concluded that extraoral osseointegrated implants in humans may integrate morphologically as well as clinically. By microradiography it was possible to define bone metal contact in the region of implant installation.

Adult↗
PubMedDate not supplied

Fluoride and urea chewing gums in an intra-oral experimental caries model.

The aim of the present investigation was to evaluate the effect of sugar-free chewing gums containing fluoride (F) and urea in an intra-oral experimental caries model. Placebo chewing gums (without any active ingredient) and no gum served as controls. Fifteen subjects participated in a cross-over, single-blind study. Demineralised enamel and dentine blocks were embedded in circular plastic discs and bonded to the buccal surfaces of the lower canines and first premolars. The discs were removed and analysed using transversal microradiography after each of the six 4-week periods during which the subjects used either test or placebo products or no product. The results revealed that frequent use of sugar-free chewing gum is sufficient to inhibit further demineralisation of previously demineralised enamel and dentine specimens in the oral cavity. Comparing F, urea and placebo gums, the data showed that there was little or no difference between the products, except for an inhibitory effect on the chewing side of the dentition after using F chewing gums.

Adult↗
PubMed2006

Light-emitting diode illumination design with a condensing sphere.

An illumination system is described that comprises a glass or plastic sphere, an embedded light-emitting diode (LED) source, and a reflecting or scattering mirror. The rays from the LED are either refracted in the forward direction or totally internally reflected by the sphere. The mirror breaks the total internal reflection and thus sends the rays in the forward direction. The illumination pattern and efficiency of the system are analyzed. This system is extremely compact and efficient and is a good starting point for a complex illumination system design.

Journal Article↗
PubMed2005

Microfluidic tool box as technology platform for hand-held diagnostics.

BACKGROUND: Use of microfluidics in point-of-care testing (POCT) will require on-board fluidics, self-contained reagents, and multistep reactions, all at a low cost. Disposable microchips were studied as a potential POCT platform. METHODS: Micron-sized structures and capillaries were embedded in disposable plastics with mechanisms for fluidic control, metering, specimen application, separation, and mixing of nanoliter to microliter volumes. Designs allowed dry reagents to be on separate substrates and liquid reagents to be added. Control of surface energy to +/-5 dyne/cm2 and mechanical tolerances to < or = 1 microm were used to control flow propulsion into adsorptive, chromatographic, and capillary zones. Fluidic mechanisms were combined into working examples for urinalysis, blood glucose, and hemoglobin A(1c) testing using indicators (substances that react with analyte, such as dyes, enzyme substrates, and diazonium salts), catalytic reactions, and antibodies as recognition components. Optical signal generation characterized fluid flow and allowed detection. RESULTS: We produced chips that included capillary geometries from 10 to 200 microm with geometries for stopping and starting the flow of blood, urine, or buffer; vented chambers for metering and splitting 100 nL to 30 microL; specimen inlets for bubble-free specimen entry and containment; capillary manifolds for mixing; microstructure interfaces for homogeneous transfer into separation membranes; miniaturized containers for liquid storage and release; and moisture vapor barrier seals for easy use. Serum was separated from whole blood in <10 s. Miniaturization benefits were obtained at 10-200 microm. CONCLUSION: Disposable microchip technology is compatible with conventional dry-reagent technology and allows a highly compact system for complex assay sequences with minimum manual manipulations and simple operation.

Blood Glucose↗
PubMed2004

Techniques for thick-section Golgi impregnation of formalin-fixed brain tissue.

The histologic staining technique for central nervous system (CNS) tissue known as the Golgi technique was initially developed more than 125 yr ago. It was with this technique that, for the first time, whole nerve cells and their processes were simultaneously observed microscopically. Although the technique was widely used in the early 20th century, its use languished to some extent until the late 1900s when, used in conjunction with ultrastructural studies, it began to provide new insights into microscopic anatomy and pathology of the CNS. Several permutations of the technique have evolved since its early stages. The one represented in this chapter was developed so that Golgi-impregnated CNS tissues could be embedded in polymerized plastic and cut into relatively thick sections for light microscopic study. The advantages are that (a) sections of the clear and almost colorless plastic allow enhanced visualization of the intricate structure and ramification of dendritic elements of CNS neurons, (b) because of the relatively thick microscopic sections (25-30 micro m), details of lengths and arborization of dendritic "trees" can be studied and photographed to provide greater detail than in thinner sections, and (c) numbers and morphologic characteristics of synaptic spines can be precisely evaluated.

Animals↗
PubMed1983

Optimized transection: a prelude to oriented sectioning.

A technique is described which permits blocks of tissue to be flat-embedded in euhedral plastic castings and then to be transected along a plane so that sections may be cut which are optimally oriented to the internal ultrastructure of the block. In the transection procedure a hollow plastic cylinder is placed on the specimen trimming block. The cylinder's top prescribes a plane to which the tissue block is accurately oriented and clamped at a predetermined level. Two hand files and a burnisher are worked across the cylinder's top to 1) remove extraneous material above the plane of transection, 2) expose the tissue for sectioning and 3) smooth the block face. The clear plastic at the periphery of the exposed tissue is then easily trimmed away with a razor blade. The result is a block face with a flat, reflective surface which may be quickly aligned to the knife on the ultramicrotome. The effort needed to transect, align and face the block is minimal and 1-micron or semithin sections produced will be precisely parallel to, and at, the plane of transection. Dust produced by the transection procedure is easily eliminated from the work area by use of a small disposable vacuum cleaner. The technique of producing optimally oriented light microscope sections, using the transector, is enhanced by application of solvents to the block face which cause it to develop a temporary low relief, exactly matching the structural detail of sections cut from the block face.(ABSTRACT TRUNCATED AT 250 WORDS)

Histological Techniques↗
PubMed1978

A proposed selective cell carcinogenesis in mammary tumors.

The present study was done to ascertain whether a specific carcinogenic agent has a causal effect on the initial proliferation of only one cell type or whether it acts indiscriminately on all cells in the breast secretory unit. Enzymes histochemistry and electron microscopy were performed on DMBA-induced mammary tumors in female Sprague-Dawley rats and on virus-associated spontaneous mammary tumors in C3H/HEJ mice. The results showed that the chemical carcinogen DMBA affects initial myoepithelial cell proliferation, while virus-associated mammary carcinoma originated from ductular epithelial cell proliferation. To determine whether a specific tumor is composed of a single cell type, tumors were grown in tissue culture. The monolayer was fixed in the usual manner for electron microscopy while in Falcon tissue culture plates. The plates were dissolved in xylene and the monolayer was cut into small pieces and embedded in the plastic media. Electron microscopy performed on the tissue culture and the original tissue from the virus-induced tumors showed the presence of viruses in large numbers. It also suggested the differentiation of basal membrane to form basal lamina and apical plasma membrane into microvilli. This study strongly suggests the presence of selective cell carcinogenesis in the mammary gland.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Electron spectroscopic imaging and X-ray microanalysis of phosphorus in mouse sperm chromatin.

The influence of HCl hydrolysis on DNA detection in a Feulgen-type reaction using osmium ammine has been analyzed at the electron microscopic level by means of electron spectroscopic imaging, electron energy loss spectroscopy and X-ray microanalysis in energy dispersive spectroscopy. Both the stained DNA and the phosphorus mapping for a given hydrolysis condition were studied in parallel on the same nucleus. We have found that the pattern of osmium ammine-stained DNA and phosphorus imaging can be superimposed for a short hydrolysis time. After long HCl treatment, DNA is barely detectable by osmium ammine while phosphorus is still present in the thin sections. Taking into account the fact that the cells are embedded in a plastic resin, it is reasonable to think that in this case DNA depolymerization does not completely correspond to DNA loss. An incomplete loss of this highly denatured and depolymerized DNA from the plastic sections will explain both the presence of phosphorus and the poor stainability with a Schiff-type reagent.

Animals↗
PubMed1991

Subchondral architecture in bones of the canine shoulder.

The distal scapula and proximal humerus from each shoulder of nine adult dogs were slab-sectioned, cleaned of soft tissues, embedded in white plastic and stained black with a silver stain. These preparations were then photographed for automated, digital, morphometric analysis of subchondral bone structure. Comparison of transverse and coronal sections through the left and right shoulders demonstrated essential isometry of trabecular patterns within each bone. Comparison of the scapula and humerus revealed significant differences in bony architecture. The subchondral plate was an average of 5.6 times thicker under the glenoid fossa than in the opposing humeral head. Deeper trabecular structure also differed with the trabecular bone volume (density) in the humerus being greater than that in the scapula. This difference reflects a greater trabecular density in the humerus with comparable trabecular thickness in both bones. These structural differences are consistent with previous functional studies of the same two bones that revealed greater mechanical stiffness beneath the glenoid fossa and greater hydraulic resistance within the humeral head.

Animals↗
PubMed1980

Automation of blood film preparation and staining utilizing the technicon autoslide.

Evaluation of a prototype Technicon Autoslide, which automatically prepares, fixes, stains, dries labels, and "coverslips" blood films, attached to a Technicon Hemalog D-90 revealed that the instrument prepares high-quality wedge blood smears with uniform distribution of leukocytes, excellent red blood cell and platelet morphology, and adequate staining of normal types of leukocytes. The fixation-staining characteristics did not enable reliable identification of some immature cell types. An additional 200 microliters of blood samples is requred above that required for the Hemalog D-90 in order to prepare a smear. The throughput time of the instrument, from sample aspirate to completion of the blood smear, is 14 min. One sample is completed every 45s. The final glass-slide specimen contains the blood smear sample and its identification and date, embedded in acrylic plastic, which also serves as a coverslip. The instrument can be operated by the D-90 operator with negligible additional effort. The approximate cost of each sample was 8.25 cents. The Autoslide in combination with the Hemalog D-90 should reduce technician time required to prepare, stain, and label blood smears. Its use should reduce the frequency of sample misidentification and provide more uniform quality to slide preparation and staining than is available by current manual techniques. Preliminary studies suggest that Autoslide smears are suitable for use on an image-processing type of automated differential system, and this therefore makes their use possible in a tiered screening system for detection of platelet or red cell abnormalities not recognized by the high-volume cell-counting instruments.

Autoanalysis↗
PubMedDate not supplied

Imaging factors influencing spine and cord measurements by CT: a phantom study.

Metrizamide computed tomography (CT) of the spine allows evaluation of the contents and measurement of the size of intracanalicular structures. The relative size (linear and area measurements) of spinal structures can be changed by varying imaging factors or the density of intrathecal contrast material. Two phantoms, one consisting of rods embedded in a plastic cylinder and the other of a vertebral body with a central rod simulating spinal cord, were evaluated with varying imaging factors (window width and window level) and different contrast concentrations within the surround. It was found that wide window widths allowed the most consistent measurements independent of window level, that a window level midway between the CT number of rod and surround would facilitate uniform measurements independent of window width, and that the use of high concentrations of contrast material (high CT number) in the surround, in combination with a wide window width, was most effective in establishing consistent measurements.

Humans↗
PubMed1996

[Use of low temperature methods with optically stimulated luminescence for measuring ionizing radiation doses].

A new method of cooled optically stimulated luminescence (COSL) based on CaF2:Mn crystals has become the subject of numerous studies carried out by the Pacific Northwest Laboratory in the United States. The method has developed and expanded the feasibility of measuring ionizing radiation doses based on a classical phenomenon of thermoluminescence. Much greater sensitivity of the new method allows to measure doses of 10 microR order. A manifold reading of a given dosimeter is also feasible. That facilitates the elimination of doubtful readings. The reading of a dose from the dosimeter and cleaning for its reuse is performed in temperatures not higher than room temperature. Therefore, dosimeters in the form of powder embedded in a plastic matrix which imitates live tissue, can be easily used, whereas thermoluminescence method would cause melting of a dosimeter during its reading. The authors made an attempt to get acquainted the reader with extremely interesting method for measuring ionizing radiation doses.

Radiation Dosage↗
PubMed1998

Reduced mucosal perianastomotic capillary density in rat small intestine with chronic radiation damage.

Anastomoses in an intestine with chronic radiation damage are prone to leakage, possibly due to a reduced blood supply induced by a reduced capillary bed. In an animal model, the numerical capillary density in the perianastomotic area was investigated in intestine with or without chronic radiation damage. A 2-cm segment of rat ileum received a single dose of 21 Gy. Twenty weeks later, when the chronic radiation-induced changes were established, an anastomosis was constructed in this segment and in a corresponding segment in control rats. In situ perfusion fixation of the intestine was done 4 or 7 days after construction of the anastomosis, sections of the intestine were removed surgically, the specimens were embedded in methacrylate plastic and sectioned at 2.5 microm, and capillaries were counted under a light microscope. The circumferential mucosal capillary density was lower in irradiated than in nonirradiated animals at both 4 and 7 days (P < 0.001 and P = 0.04, respectively). This reduction was greater in the mesenteric quadrant than in the other quadrants around the circumference. These results are indicative of a reduced capillary bed in the vicinity of anastomoses in intestine with chronic radiation damage, which might lead to an impeded blood supply and subsequent leakage.

Anastomosis, Surgical↗
PubMed1995

An osmium-free method of epon embedment that preserves both ultrastructure and antigenicity for post-embedding immunocytochemistry.

Immunocytochemistry for amino acids with post-embedding gold is compatible with glutaraldehyde fixation, osmication, and embedding in epoxy-based plastics, but immunogold detection of larger molecules in the central nervous system commonly requires special procedures, e.g. minimizing exposure to glutaraldehyde, eliminating osmium, cryosectioning, and/or embedding in acrylic plastics. These make samples more difficult to prepare and view and may compromise structural preservation. We report a new technique, fixing with high levels of glutaraldehyde, replacing osmium with tannic acid followed by other heavy metals and p-phenylenediamine, and embedding in Epon. This method optimizes antigenicity while retaining the structural preservation and convenient handling of standard embedding techniques. Compared to standard Epon embedment, labeling for neuropeptides in brain and spinal cord is improved. Moreover, the present method yields excellent labeling of glutamate receptors (difficult to identify with traditional post-embedding techniques) and enables simultaneous visualization of associated neurotransmitters.

Animals↗
PubMed1979

The effects of induced prenatal hypothyroidism on lamb mandibular third primary molars.

Intrauterine thyroidectomies were performed on nine lambs on or about the ninety-sixth postconception day. Seven other control and shamoperated lambs, and the cretin lambs were sacrificed immediately after birth. The mandibles were removed and sectioned at the midline. The right side molars were removed by dissection and caliper measured. The distal cusps of the third primary molars were sectioned, dehydrated, and embedded in Bioplastic. A slow speed diamond saw was used to section the plastic blocks and the embedded teeth. Subsequent grinding and polishing produced high quality 75 micrometer sections of the lamb molar cusps. No significant differences in tooth size or enamel thickness existed. Microscopic examinations show that parts of the cretin enamel were poorly calcified, an observation that was correlated to the intrauterine thyroidectomies. The data suggest that hypothyroidism alters ameloblastic activity during the secretory phase of enamel formation.

Amelogenesis↗
PubMed1979

Vertical plane serial sectioning of identified tissue culture cells.

Identifying marks can be made around specific cells on the culture surface of plastic tissue culture dishes. When the cultures are embedded in situ and the plastic dish is split away, the marks are reproduced around the cells. The marks permit trimming and complete serial sectioning of specific cells in the vertical plane.

Cells, Cultured↗
PubMed1986

Morphology, development and behavior of Pneumocystis carinii observed by light-microscopy in nude mice.

The present paper describes the morphology, development and behavior of Pneumocystis carinii, especially of the trophozoites in the alveoli of conventionally raised BALB/c nude mice, by using phase-contrast microscopy, paraffin sections and semiultrathin sections embedded in JB-4 plastic. Under phase-contrast microscopy, trophozoites were ameboid in external appearance and 2 to 8 micron in diameter. Usually they have one or more lucid spherical vacuoles and one less lucid nucleus in the cytoplasm. Maturation and independence of intracystic bodies were observed in the developing cysts. The intracystic bodies were polymorphic, i.e. spherical, ameboid or elongated. The paraffin sections using the double staining of P. carinii with Gomori's methenamine silver nitrate (GMS) and Giemsa, showed a small number of mature cysts containing intracystic bodies and a large number of trophozoites within the characteristic honeycombed material in the alveolar spaces. In order to investigate the morphology and parasitizing behavior of the trophozoites and cysts as well as the response of alveolar tissue in more detail, semiultrathin sections of 0.5-2 micron thickness were made from the materials embedded in JB-4 plastic and stained with Giemsa. In lightly infected alveoli, some trophozoites and cysts were found to be closely attached to the Type I alveolar epithelial cells. In heavily infected alveoli, almost all alveoli were filled with trophozoites, cysts, debris of the host cells, and occasionally phagocytic cells (macrophages and neutrophils) containing cysts or trophozoites were found. It was noted that the cysts were very few in number (1%) compared with the number of the trophozoites in nude mice in a 0.4 mm2 area of 2 micron thick lung sections. The host tissue of nude mice in this study was not as strongly affected by the organisms as that in cortisone-treated rats and P. carinii pneumonia patients. In the present study the morphology of P. carinii found in nude mice was not different from that found in rats and in man.

Animals↗
PubMed1995

Use of quantitative ultrastructural immunoperoxidase labeling for analysis of catecholamine neurotoxicity and plasticity.

Levels of catecholamines and the synthesizing enzyme, tyrosine hydroxylase (TH) are markedly decreased in the dorsal striatum, caudate-putamen nuclei, following neurotoxic lesions with 6-hydroxy-dopamine (6-OHDA). We examined whether pre-embedding immunoperoxidase labeling of TH could be standardized for quantitatively examining the density and ultrastructure of spared dopaminergic terminals in the striatum of lesioned rats. The peroxidase-antiperoxidase (PAP) method was used to localize rabbit antiserum against TH in caudate-putamen nuclei of adult rats given unilateral nigral injections of either vehicle or 6-hydroxydopamine in the early postnatal period. Experimental differences in fixation and immunocytochemical labeling were minimized by limiting comparisons of immunoreactivity to co-processed sections from the same litters of animals. Imaging software and a Phillips CM-10 electron microscope were used to quantitatively examine immunoreactive profiles in a narrow zone of tissue in contact with the embedding resin. Under these conditions variables attributed to differences in penetration were minimized. There were no significant differences in numbers or mean-cross sectional diameter of immunoreactive terminals in striatum ipsilateral versus contralateral to vehicle injections. Ipsilateral to the 6-OHDA injections, the density (numbers/area) of striatal TH-immunoreactive terminals was reduced by 50-90% in the majority of animals. In the most extensively lesioned rats, the cross-sectional areas of the remaining immunoreactive axons were significantly larger than in the contralateral striatum of the same animal or either hemisphere of vehicle injected controls. These results confirm and extend earlier findings on the plasticity of residual dopaminergic terminals in adult animals after neurotoxic damage. They also establish a quantitative method for ultrastructural analysis of the density of immunoreactivity in thick sections of tissue labeled prior to plastic embedding. The method has broad applicability to quantitative studies of neurotoxicity and plasticity in brain.

Animals↗