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PubMed1998

Chicken (Gallus domesticus) inner ear afferents.

Neurons from the vestibular (VG) and the statoacoustic (SAG) ganglion of the chick (Gallus domesticus) were evaluated histologically and morphometrically. Embryos at stages 34 (E8 days), 39 (E13 days) and 44 (E18 days) were sacrificed and temporal bones microdissected. Specimens were embedded in JB-4 methacrylate plastic, and stained with a mixture of 0.2% toluidine blue (TB) and 0.1% basic Fuschin in 25% ethanol or with a mixture of 2% TB and 1% paraphenylenediamine (PDA) for axon and myelin measurement study. Images of the VIIIth nerve were produced by a V150 (R) color imaging system and the contour of 200-300 neuronal bodies (perikarya) was traced directly on a video screen with a mouse in real time. The cross-sectional area of VG perikarya was 67.29 micrometers2 at stage 34 (E8), 128.46 micrometers2 at stage 39 (E13) and 275.85 micrometers2 at stage 44 (E18). The cross-sectional area of SAG perikarya was 62.44 micrometers2 at stage 34 (E8), 102.05 micrometers2 at stage 39 (E13) and 165.02 micrometers2 at stage 44 (E18). A significant cross-sectional area increase of the VG perikarya between stage 39 (E13) and stage 44 (E18) was determined. We randomly measured the cross-sectional area of myelin and axoplasm of hatchling afferent nerves, and found a correspondence between axoplasmic and myelin cross-sectional area in the utricular, saccular and semicircular canal nerve branches of the nerve. The results suggest that the period between stage 34 (E8) and 39 (E13) is a critical period for afferent neuronal development. Physiological and behavioral vestibular properties of developing and maturing hatchlings may change accordingly. The results compliment previous work by other investigators and provide valuable anatomical measures useful to correlate physiological data obtained from stimulation of the whole nerve or its parts.

Animals↗
PubMed1985

Abscissic acid localization by light microscopic immunohistochemistry in Chenopodium polyspermum L. Effect of water stress.

An indirect immunohistochemical technique was developed using a rabbit anti-abscissic acid (ABA) serum and the soluble peroxidase-antiperoxidase (PAP) complex for the localization of endogenous ABA in the aerial parts of Chenopodium. Terminal bud, axillary bud bearing nodes, and adult leaves were prefixed by a soluble carbodiimide to obtain the coupling of ABA on cellular proteins and postfixed by a conventional mixture of aldehydes. They were then embedded in paraffin or in plastic. Numerous controls were carried out on sections and on a model system to test the validity of the technique. Based on the staining patterns observed along the plant, an apico-basal gradient of ABA was revealed. In the older buds, ABA was mainly concentrated in the quiescent meristematic cells of the apex. Phloem cells of the main axis and chloroplasts of the leaves were specifically labeled. No reaction product was visualized in the parenchyma cells or in the cambial zone. Water stress, which is known to increase ABA content, induced an increase of immunoreactivity within the same compartments. This physiological test validates the stain.

Abscisic Acid↗
PubMed1988

Quantitative digital radiography versus dual photon absorptiometry of the lumbar spine.

Lumbar spine bone mineral density (BMD) was measured by quantitative digital radiography, a new dual energy x-ray technique, and by 153Gd dual photon absorptiometry (DPA) in 85 patients. Each patient was measured twice by the new method and once by DPA on the same day, with repositioning between measurements. Serial measurements were made on an hydroxyapatite spine phantom embedded in tissue-equivalent plastic to evaluate the long term reproducibility of each instrument. The spinal BMD measurements with the 2 techniques were linearly related and highly correlated (r = 0.98) over a range from severely osteopenic to high normal. This correlation was not affected by the age, weight, or BMD of the patient measured. Quantitative digital radiography's long-term reproducibility using the spine phantom was stable for 180 days (coefficient of variation, 0.23%); DPA values were 3 times as variable for 170 days (coefficient of variation 0.73%) and increased 1.0% (P less than 0.0001) after a software change. The short term reproducibility of quantitative digital radiography, estimated from paired patient measurements, was 2-fold better than reported values for DPA and was independent of the patient's age, weight, or BMD. Measurement time by quantitative digital radiography was 5-8 min, with a maximum radiation exposure of 3 mrem, significantly lower than the corresponding DPA values. Quantitative digital radiography's image resolution was superior to that of DPA, enabling it to measure more bones. These advantages along with the elimination of 153Gd source changes and Nuclear Regulatory Commission licensing requirements indicate that quantitative digital radiography is the superior method for spinal BMD measurements.

Adult↗
PubMed1990

Cement line staining in undecalcified thin sections of cortical bone.

A technique for demonstrating cement lines in thin, undecalcified transverse sections of cortical bone has been developed. Cortical bone samples are processed and embedded undecalcified in methyl methacrylate plastic. After sectioning at 3-5 microns, cross-sections are transferred to a glass slide and flattened for 10 min. Sections of cortical bone are stained for 20 sec free-floating in a fresh solution of 1% toluidine blue dissolved in 0.1% formic acid. The section is dehydrated in t-butyl alcohol, cleared in xylene, and mounted with Eukitt's medium. Reversal lines appear as thin, scalloped, dark blue lines against a light blue matrix, whereas bone formation arrest lines are thicker with a smooth contour. With this technique cellular detail, osteoid differentiation, and fluorochrome labels are retained. Results demonstrate the applicability of a one-step staining method for cement lines which will facilitate the assessment of bone remodeling activity in thin sections of undecalcified cortical bone.

Animals↗
PubMed1990

Cement line staining in undecalcified thin sections of cortical bone.

A technique for demonstrating cement lines in thin, undecalcified, transverse sections of cortical bone has been developed. Cortical bone samples are processed and embedded undecalcified in methyl methacrylate plastic. After sectioning at 3-5 microns, cross-sections are transferred to a glass slide and flattened for 10 min. Sections of cortical bone are stained for 20 sec free-floating in a fresh solution of 1% toluidine blue dissolved in 0.1% formic acid. The section is dehydrated in t-butyl alcohol, cleared in xylene, and mounted with Eukitt's medium. Reversal lines appear as thin, scalloped, dark blue lines against a light blue matrix, whereas bone formation arrest lines are thicker with a smooth contour. With this technique cellular detail, osteoid differentiation, and fluorochrome labels are retained. Results demonstrate the applicability of a one-step staining method for cement lines which will facilitate the assessment of bone remodeling activity in thin sections of undecalcified cortical bone.

Animals↗
PubMed2004

[The effect of different fabrication methods and luting cements on post retention].

OBJECTIVE: This study was to compare the retention of posts fabricated by different methods and cemented with various cements in order to provide a guidance for clinical choice of post fabrication methods and luting cements. METHODS: Ninety human maxillary anterior teeth were sectioned by the cementoenamel junction and post-holes were prepared. All roots were embedded in the center of plastic cylinders and paralleled with the cylinder. All samples were divided into 9 groups randomly and equally. Posts fabricated with different methods were then cemented with different luting cements. Each sample was placed into a specialized jig and mounted on a tensile testing machine with crosshead speed of 5 mm/min. Constant tensile force was applied until the post was dislodged, and the tensile force required to dislodge the cemented post was recorded. RESULTS: The mean retention force of parapost and direct post demonstrated significantly higher than that of indirect post did (P < 0.05), but there was no significant difference between parapost and direct post(P > 0.05). The mean retention of parapost cement demonstrated significantly higher than that of ZPC and HY-Bond cement did (P < 0.05), but there was no significant difference between ZPC and HY-Bond cement (P > 0.05). CONCLUSION: Different fabrication methods and luting cements significantly affect the retention of posts; and there exists an interaction between different fabricating methods and luting cements.

Cementation↗
PubMed2004

[Endoscopic, pathologic-anatomic and histologic findings in the bovine teat. 2. Changes in the area of Fürstenberg's rosette].

In the present study endoscopically diagnosed changes of the Fürstenberg's rosette were examined histologically. For this purpose the teats of 200 slaughtered cows were inspected. In 19 cases proliferations in the region of the Fürstenberg's rosette were found. Additionally, tissue samples were taken from the Fürstenberg's rosette of 26 cows which showed milk flow disorders due to stenoses of this part of the teat. Teats of slaughtered cows as well as biopsy specimens were fixed in 5% formaldehyde and embedded in paraffin and in plastic. All specimens were stained according to H.E., Giemsa and Turnbull, respectively. Histologically, the proliferations of the Fürstenberg's rosette consisted of fibrovascular tissue (granulation tissue) covered by keratinized squamous epithelium (teat canal epithelium) in eleven cases. In the other cases double-layered cuboid epithelium (cisternal epithelium) was found additionally. The formation of granulation tissue and deposition of blood pigment was observed exclusively in areas covered by stratified epithelium. Therefore a traumatic lesion of the teat canal was supposed to be the cause of the histological findings. In contrast to several reports in the literature, however, no indications of an inversion of the teat canal epithelium were found. On the basis of these findings, the hitherto assumed idea of pathogenesis of proliferations of the Fürstenberg's rosette was modified and a new pathogenesis pattern was developed.

Animals↗
PubMedDate not supplied

Detailed examination of complete bioprosthetic heart valves.

Six (3 control and 3 explanted) bioprostheses were examined histologically after embedding the complete valve in "plastic" and sectioning across the valve at 90 degree to the horizontal plane, and then horizontally across a stent post, with a low speed saw. The prostheses, porcine or pericardial, had been in place 52 to 121 months. In addition to cusp changes of degeneration and calcification that have been previously reported, the authors found extensive pannus deposition on the cloth covering the inflow surface of the prostheses, with some extension onto the biologic components; evidence of insudation of tissue fluid and ingrowth of fibroblasts; deposition of collagen; and infiltration of mononuclear cells in the interstices and interfaces. Non-biologic components showed changes which may have affected prosthesis function. The synthetic material covering the metal/plastic frame showed interstitial mononuclear cells. Two of the three explanted valves showed changes in the polymeric plastic, and one in the metal components, including accentuated notching along the surfaces when compared to unimplanted prostheses. A larger number of prostheses must be examined before definite conclusions can be drawn.

Adult↗
PubMed1989

[The size of the overlapping of the gingival margin in Class II amalgam fillings examined in the teeth and their radiographic images].

200 Class II extracted teeth provided with amalgam filling were examined. The size of the overlapping of the fillings were measured on the X-ray pictures and in the transverse section of the teeth embedded in self-cementing plastic under a stereomicroscopy by means of an ocular micrometer. The mean overlapping of the fillings was 0.52 +/- 0.44 millimeters on the teeth and 0.48 +/- 0.43 millimeters on the X-ray pictures. There was no significant difference between the values obtained by both methods. On the upper teeth [teeth: 0.64 +/- 0.50 millimeter, X-ray: 0.59 +/- 0.48 millimeters (significantly) P less than 0.001] the overlapping of the fillings was greater than on the lower ones (teeth: 0.39 +/- 0.49 millimeters, X-ray: 0.36 +/- 0.33 millimeters). The other comparisons did not show any significant difference by either method. The oro-vestibular extension of the overlapping gingival filling borders was, on the average 3.45 +/- 1.25 millimeters and amounted to 46.25 +/- 15.94% of the width of the surfaces. The percentual oro-vestibular extension of the gingival filling borders was significantly greater (p less than 0.05) on the premolars than on the molars. The gingivally overlapping filling showed also an oral and/or vestibular overlapping.

Bicuspid↗
PubMed1987

In vitro quantitative study of newly made antibacterial braided nylon sutures.

This study was done to examine quantitatively the antibacterial property of a newly made, silver compound coated braided nylon suture and to confirm the previously reported qualitative antibacterial data. Three representative bacterial species were used and they were Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The suture specimens were embedded in a custom built plastic device filled with a fixed concentration of bacteria for predetermined periods of incubation. A direct current ranging from 0.4 to 40.0 microamperes was applied to the suture specimens. The bacterial suspension was periodically removed for a standard plate count in order to determine quantitatively the antibacterial capability of the suture specimens. The amounts of silver ions released to the medium under various direct current levels were also determined by a pH/ion meter. The antibacterial property of the suture was evident in the anode site of the material, and at a fixed current, the degree of bacteriostatic effect depended upon the type of bacterial species. For example, a difference of almost 10(3) in the number of Pseudomonas aeruginosa was observed within a period of six hours. The responses of Staphylococcus aureus and Escherichia coli to the silver compound coated nylon thread, however, were not as drastic as Pseudomonas aeruginosa. These quantitative data were consistent with the previously reported qualitative observation of the width of clear zone in bacterial culture plates. The silver ion concentration in the medium increased with increasing either the current level or time, or both. At the end of six hours, the ion concentrations were 7.3 micrograms per milliliter at 0.4 microampere, 44.3 micrograms per milliliter at 4.0 microamperes and 305.7 micrograms per milliliter at 40.0 microampere.

Anti-Bacterial Agents↗
PubMed1988

Dosimetry considerations in far field microwave exposure of mammalian cells.

A circulating water bath exposure system has been designed for in vitro radiofrequency radiation (RFR) exposure studies in the 915 to 2450 MHz range. A Styrofoam float, in which 10 T-25 plastic tissue culture flasks are embedded, is rotated at approximately 20 rpm in a Plexiglas water bath at a distance beneath a rectangular horn. The continuous circular rotation of the flasks is designed to "average out" the heterogeneity present in stationary flask exposures. The rotation also serves to prevent the establishment of chemical gradients in the medium within the flasks. Several factors have been demonstrated to affect the specific absorption rate (SAR) measured in the medium in the exposed flasks. These factors include: 1) the position of the exposure flasks relative to the long axis of the antenna horn; 2) whether the flasks are exposed while stationary or in rotation; 3) the volume of the medium contained in the flask; and 4) the depth in the medium in the flask at which temperatures for SAR calculation are measured. The presence of cells in the exposure flask (as attached monolayer or cell suspension) did not result in an SAR different from that measured in the same volume of medium without cells present.

Cells↗
PubMed1985

Eye-specific segregation requires neural activity in three-eyed Rana pipiens.

The addition of a third eye primordium to the forebrain region of a Rana pipiens embryo invariably results in the development of a series of periodic, mutually exclusive eye-specific bands in tectal lobes dually innervated by the host and supernumerary fibers. A number of investigators have proposed that such source-specific segregation arises as a compromise between two mechanisms that are normally involved in retinotectal map formation: one which is dependent on cell surface affinities to align the map and produce a rough retinotopy and a second that "fine tunes" the map by stabilizing adjacent terminals from neighboring retinal ganglion cell bodies at the expense of terminals from non-neighboring cells. In this study we have tested the idea that this second "fine-tuning" mechanism is dependent on neural activity by blocking impulse activity in the optic nerves of three-eyed tadpoles. To assess the requirement for activity on the formation of bands, both normal optic nerves of 17 three-eyed tadpoles were crushed intraorbitally. Two weeks after this operation, the supernumerary retinal projection had debanded and spread to cover the entire tectum in a continuous fashion. By 4 weeks, however, the host optic fibers regenerated back to the tecta and began to form segregated stripes with the fibers from the third eye. Six to 7 weeks after the optic nerve crush the periodic pattern of eye-specific segregation characteristic of dually innervated tecta was again pronounced. When activity in all three optic nerves was eliminated with tetrodotoxin (TTX; embedded in a slow release plastic) during the last 3 weeks of this process, the fibers from the two competing eyes failed to segregate and, instead, formed two completely overlapping, continuous projections across the tectal surface. To test for the requirement of activity in the maintenance of segregation, we also subjected three-eyed tadpoles without optic nerve crush to TTX blockade for 2, 3, and 4 weeks. Animals sacrificed at 2 weeks show overlap of the projections in the rostral tectum but distinct interdigitating stripes in other regions of these lobes. After 3 weeks of blockade, segregation of the projections was less distinct in the central tectum as well. After 4 weeks of TTX blockade the terminals from both eyes spread to form continuous overlapping projections throughout the tectum. Examination of well isolated, individual retinal ganglion cell terminal arbors during this period reveals that they occupy a significantly greater area of tectum following the TTX treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1987

Modern acrylics for post-embedding immunostaining techniques.

We describe two methods for rapid processing of biological tissues into LR White acrylic plastic. Both methods make use of LR White's compatibility with small amounts of water, enabling non-osmicated tissue to be only partially dehydrated before infiltration with the plastic, a procedure that improves the sensitivity of post-embedding immunocytochemistry. In addition, both methods are designed to reduce the time for which tissue is exposed to the damaging influence of the plastic monomer, which can cause extraction and sudden shrinkage. The tissue example used in the first method is immersion-fixed, surgically removed human pituitary which, by virtue of its thorough fixation, can be processed quickly at 50 degrees C using catalytic polymerization at room temperature. The concentration of the catalyst is critically set to prevent the temperature rising above 60 degrees C in the tissue blocks. Penetration of immunoperoxidase reagents into 330-nm LR White sections is demonstrated and possible modes of action are discussed. When "lightly" fixed tissue is processed as above, serious polymerization artifacts can result from autocatalysis. A second method, based on the first but employing slower polymerization at 0 degrees C, has therefore been developed. The high level of fine structure that can be retained using this method is illustrated by the demonstration of the trans-tubular Golgi in perfusion-fixed kidney of rat. Biotinylated lectin is localized to cells of the kidney proximal tubule with streptavidin-colloidal gold, to illustrate tissue reactivity. In a second example, the structure of the bacterial cell envelope is shown to be similar in appearance after partial dehydration and LR White embedding to that seen after progressive lowering of temperature, dehydration, and Lowicryl embedding.

Acrylic Resins↗
PubMed1982

Immunocytochemical localization of water-soluble glycoproteins, including group 1 allergen, in pollen of ryegrass, Lolium perenne, using ferritin-labelled antibody.

The cellular sites of the glycoproteins Group 1 allergen (glycoprotein 1) and Antigen A (glycoprotein 2) in mature ryegrass pollen have been investigated by immunoelectron microscopy. Radioimmunoassays confirm previous findings of cross-reactivity between the purified glycoprotein antigens at the high immunoglobulin G (IgG) concentrations used for localization. Freeze-drying of anthers followed by anhydrous processing has been employed because of the water solubility and mobility of the glycoproteins. A double-embedding technique has been developed. This involves, first, embedding anthers in the water-soluble plastic resin JB-4, sectioning and incubating in ferritin-labelled antisera by the indirect method. The sections are then embedded in Spurr's resin for ultra-thin sectioning. Both glycoproteins are found in the following sites: (1) exine and intine wall layers; (2) pollen cytoplasm; (3) the orbicules and anther loculus; and (4) the anther cuticle. In the exine arcades and surface and in the anther loculus, the ferritin label is bound to pollenkitt. The finding that the glycoproteins are in similar sites is predictable in view of the cross-specificity of the antisera. The extent of antibody penetration of the plastic sections has been examined; labelling is confined to cut grains and absent from intact grains.

Allergens↗
PubMed1999

Partial and full-thickness neuroretinal transplants.

Adult and embryonic rabbit retinal sheets were transplanted into the subretinal space of adult rabbits. The transplants were either full-thickness with intact layering, or gelatin embedded and vibratome sectioned with the inner retina removed. The full-thickness grafts were positioned subretinally by means of a glass capillary in which they were partially folded. The vibratome sectioned ones were placed using a plastic injector in which the gelatin embedded graft was flat. The embryonic full-thickness grafts were followed clinically up to 3 months, and the other 3 transplant types up to 1 month postoperatively, after which the retina was sectioned and stained for light microscopy. Surgical complications were more common in eyes receiving vibratome sectioned grafts with 10 out of 34 eyes displaying blood in the vitreous. Four of these eyes also developed total retinal detachment. Out of 17 eyes receiving full-thickness grafts, only one displayed these complications. Histologically, 11 out of 13 embryonic full-thickness transplants revealed straight, laminated transplants with correct polarity, and with all normal retinal layers present. In these transplants, fusion with the host increased in time. Of the adult full-thickness transplants, only 1 out of 4 survived, and this graft showed signs of degeneration. The vibratome sectioned adult transplants in a few cases survived the first two postoperative weeks. In these grafts, both inner and outer retina were present, indicating an incomplete vibratome sectioning. With longer postoperative times, the number of surviving transplants in this group diminished considerably. All vibratome sectioned embryonic transplants developed into rosettes and sometimes also into laminated sections with reversed polarity. It can be concluded that in rabbits, the surgical technique used for vibratome sectioned transplants requires a larger sclerotomy and retinotomy, since they have to be kept flat in the transplanting instrument due to the surrounding gelatin. This technique is associated with a higher frequency of complications than the one used for full-thickness grafts which are more flexible and can be transplanted with a smaller instrument. Vibratome sectioning of embryonic grafts results in abnormal morphology and their adult counterparts only survive if the sectioning is incomplete. Adult full-thickness grafts show poor survival. Embryonic full-thickness transplants in the majority of cases develop into laminated retinas with layers parallel to the host retinal pigment epithelium. They also survive and integrate well with the host retina.

Animals↗
PubMedDate not supplied

Notes on the application of microwaves for antigen retrieval in paraffin and plastic tissue sections.

In formalin-fixed, paraffin-embedded tissue enhanced or de novo immunostaining can be obtained by microwave boiling of sections in a metal salt or buffer solution. In this paper this new technique is reviewed and important factors influencing final results are discussed. Microwave antigen retrieval can also be applied for immunohistochemistry on plastic GMA sections. Here the action of the microwave method is probably mainly due to breaking the bonds between GMA and proteins prohibiting immunostaining. The microwave methods do not require trypsin treatment.

Aluminum Chloride↗