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PubMed1988

Influence of antihypertensive treatment on basal cerebral arteries in spontaneously hypertensive rats. A morphometric study.

Spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) were treated with a combination of a beta 1-blocker (metoprolol) and a calcium antagonist (felodipine) from 1 to 4 or from 4 to 6 months of age. Basal cerebral arteries were fixed by immersion and embedded in plastic. The ratio between media thickness and luminal radius was determined in cross-sectioned arteries for a standardized condition, assuming a smooth and circular internal elastic membrane. The treatment caused a significant decrease in blood pressure and a normalization of m/r ratios in basal cerebral arteries when initiated in young as well as in adult SHR and SHRSP, i.e. the therapy efficiently prevents as well as reverses hypertensive arterial changes. Even though 4-month-old treated rats were still significantly hypertensive, their m/r ratios did not differ from those of normotensive controls. The latter results may indicate that the treatment affects the vessel walls also through other mechanisms than by decreasing the pressure load.

Animals↗
PubMed1993

Direct estimation of volumes in ovarian follicles using the nucleator.

The aim of the study was to evaluate the precision of the nucleator principle with regard to estimation of follicle, oocyte and antral volumes in individual follicles, as well as their average volumes in a group of follicles. Nine isolated murine ovarian follicles embedded in plastic were orientated isotropically, cut into 20 microns serial sections, and stained with hematoxylin. In each follicle the volumes of the follicle, the antrum and the oocyte were estimated in two ways, both unbiased: Firstly, in just one unique section through the follicle, viz. the section which contains the unique sampling point--the nucleolus of the oocyte--using the nucleator principle, and, secondly, in the complete set of follicle sections using the Cavalieri principle. Estimates using the Cavalieri, which are very precise (CEFollicle approximately 0.03, CEOocyte approximately 0.11, CEAntrum approximately 0.16), were interpreted as the "true" values. Therefore, the precision (estimator variation) of the nucleator estimates could be calculated. The nucleator estimates correlated well with the Cavalieri estimates: r(follicle) = 0.95; r(antrum) = 0.88; r(oocyte) = 0.83. The nucleator provides very precise estimates of the volumes of follicle, oocyte and antrum with a minimal amount of effort, since the estimates are derived from measurements in only four directions sampled in a uniform systematic way, the first direction being chosen at random, in only one section through the follicle. Moreover, it is not necessary to know the precise thickness of the section, and finally, the estimates are expressed in correctly dimensioned terms. The estimator variation of the nucleator (CE = 0.28) is of minor importance compared to the biological variation (CV = 0.47) in this realistic sample of follicles.

Animals↗
PubMed2002

Histologic evaluation of a human immediately loaded titanium implant with a porous anodized surface.

BACKGROUND: Several researchers have demonstrated, in the past decade, in clinical and histologic studies, that immediate loading can be successfully used in implant dentistry. Many factors are thought to be of importance in obtaining mineralized tissues at the interface. One of these factors is the implant surface characteristics. Recently, an implant with a new porous anodized surface has been introduced in the market. PURPOSE: The goal of this study was to histologically evaluate a clinically retrieved immediately loaded implant with a porous anodized surface. MATERIALS AND METHODS: After a 6-month loading period, an immediately loaded implant with a porous anodized surface that had been inserted in the posterior maxilla was retrieved. RESULTS: Histology showed that mineralized tissue was present at the interface and the bone-implant contact percentage was about 60%. No gaps or fibrous tissue or inflammatory infiltrate were present at the interface. CONCLUSIONS: Results show that immediate loading of dental implants has no untoward effects on the formation of mineralized tissues at the interface. Immediate loading is a possible alternative in implant dentistry. key words: dental implants, histology, immediate loading, oxide coating, porous surface

Benzenesulfonates↗
PubMed2004

Interimplant distance and crestal bone resorption: a histologic study in the canine mandible.

BACKGROUND: Crestal bone loss has been shown to occur around dental implants. This crestal bone resorption may determine a more apical position of the gingival margin. A clear trend of increased bone loss with increased interimplant distance has been reported. PURPOSE: The aim of the present study was to evaluate, in the canine mandible, the crestal bone behavior around dental implants inserted with different interimplant distances. MATERIALS AND METHODS: Sandblasted and acid-etched implants (Bone System, Milano, Italy) were placed in the mandibles of six beagle dogs. Each dog received 10 implants in the mandible (five in the right side and five in the left side). A total of 60 implants was used in this study. The implants were divided in four groups: group I, with a 2 mm interimplant distance; group II, with a 3 mm interimplant distance; group III, with a 4 mm interimplant distance; and group IV, with a 5 mm interimplant distance. The dogs were killed after 12 months. RESULTS: No statistically significant differences were found in regard to vertical bone loss whereas on the contrary, statistically significant differences were found in regard to lateral bone loss (p = .0001). Statistically significant differences also were found in regard to vertical crestal bone loss (p = .0001). In fact vertical crestal bone loss decreased, from 1.98 mm in group I to 0.23 mm in group IV. CONCLUSIONS: The clinical significance of these data lies in the fact that the increased crestal bone loss results in an increase in the distance between the base of the contact points of the neighboring implants and the crest of bone, and this fact could determine whether the papilla is present or absent between two implants.

Alveolar Bone Loss↗
PubMed1976

Intracellular localization of carbonic anhydrase in the frog nephron.

The intracellular distribution of carbonic anhydrase has been studied in the frog nephron by a histochemical method. The study of the detailed intracellular localization was possible by sectioning tissue embedded in plastic (Sorwall, JB-4), before staining essentially according to Hansson. This procedure preserves the intracellular structure well and the resolution is high. For light microscopy sections from 1 to 10 mum were used. For electron microscopy 0.25 mum thick sections were stained and examined in the electron microscope using an accelerating voltage of 100 kV. The highest concentrations of the enzyme seem to be localized to the cell membranes or their immediate neighbourhood. A faint cytoplasmic staining may sometimes be observed. In distal tubule cells the apical part of the cell membrane was heavily stained. Weaker staining was found at the lateral membranes and their infoldings and to some extent the basal parts of the cell membrane. In the canaliculi cells only the lateral and basal parts of the membranes were stained. This latter localization is similar to that in the parietal cells of the mammalian stomach.

Animals↗
PubMed1989

The influence of antihypertensive treatment on the mesenteric arterial structure in spontaneously hypertensive rats. A morphometric study.

Spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) were treated with a combination of a beta 1-blocker (metoprolol) and a calcium antagonist (felodipine) from 1 to 4 or from 4 to 6 months of age. The main trunk and peripheral branches of the mesenteric arterial tree were fixed by immersion and embedded in plastic. The total length of the internal elastic membrane and the media area were measured in cross-sectioned arteries. The ratio between media thickness (m) and luminal radius (ri) was then determined for a calculated, standardized condition, assuming a smooth and circular internal elastic membrane. The treatment caused a significant decrease in blood pressure and a reduction in m/ri ratios in the mesenteric arterial trunk as well as in mesenteric arterial branches when initiated in young as well as in adult SHR and SHRSP, i.e. the therapy efficiently prevents as well as reverses hypertensive arterial changes. The m/ri ratios in the superior mesenteric arterial trunks were significantly smaller in treated 4-month-old SHR and SHRSP than in WKY, although their blood pressures were not fully normalized. There was a marked increase in luminal radius in the young treated rats, possibly secondary to a therapy-induced increase in splanchnic blood flow.

Animals↗
PubMed2001

Investigation of the morphology of the lacunocanalicular system of cortical bone using atomic force microscopy.

Mechanical loading has been implicated as a powerful driving mechanism for interstitial fluid flow through bone. However, little information is available with regard to the morphology of bone fluid spaces, e.g., the canalicular wall, which would be expected to dictate the type of flow regime developing in the lacunocanalicular system under mechanical loads. The purpose of this study was to examine the fine structure of the lacunocanalicular system in cortical bone using atomic force microscopy (AFM), resin casting methods, and selective etching of the specimen surface. A resin-cast replica of the canalicular wall was produced and surface morphology and dimensions were observed using AFM in tapping mode. Material contrast was obtained using surface potential measurements. A striped pattern perpendicular to the canaliculus long axis with a periodicity of 125 nm dominated the structure of the canalicular wall; it is likely that this was caused by the imprint of collagen fibrils arranged in parallel, lining the canaliculus wall. The largest dimension measured for canalicular diameter was on the order of 500 nm. The regular dips and ridges caused by the collagen that lines the wall are a source of roughness which may influence shear stresses imparted by the fluid on the cell surface as well as mixing of solutes within the lacunocanalicular system. In addition, the lacunocanalicular wall lining is likely to affect physicochemical interactions between the fluid and bone matrix. This has important implications for modeling and understanding the microfluid mechanics and rheology of the fluid-filled lacunocanalicular network.

Animals↗
PubMed2001

Relationship between ultrastructure and the nanoindentation properties of intramuscular herring bones.

The nanoindentation technique was used to characterize the indentation modulus of intramuscular herring bone (Clupea harengus) along its length, from early to fully mineralized regions. Both the indentation modulus and modulus anisotropy ratio, indentation modulus longitudinally/indentation modulus transversely, increased nonmonotonically with mineralization, from 1.1 in the early stages of mineralization to 2.1 in the fully mineralized region. The indentation modulus in the fully mineralized region decreased from 19.9+/-2.0 GPa in the longitudinal direction to 11.4+/-1.5 GPa in the transverse directions. In the earliest stages of mineralization, the indentation modulus was 3.8+/-0.7 GPa in the longitudinal direction and 3.5+/-0.3 GPa in the transverse direction. High-intensity synchrotron x rays were used to examine two parameters of crystal texture, the coherence length and the angular spread. Low angular spread was seen along the c axis of bone crystallite. However, the large angular spread observed along the (300) plane indicated an imperfection of crystallite periodicity in the direction perpendicular to the longitudinal axis in the bone. The relatively high coherence length was related to the low angular spread. In general, the indentation modulus increased with increasing crystallite size, but the indentation modulus decreased with increasing crystallite size along the (300) plane.

Analysis of Variance↗
PubMed1989

Frequency difference limens in normal and sensorineural hearing impaired chinchillas.

This study assessed normal frequency discrimination ability in the chinchilla and determined how this ability changes as a function of an experimentally induced sensorineural hearing loss. Four chinchillas were trained by the methods of positive reinforcement to report absolute thresholds and frequency difference limens (FDLs). Subjects were then treated with the aminoglycosidic antibiotic amikacin until a 30-dB hearing loss was measured at 10.0 kHz. Absolute and frequency difference thresholds were determined during and after drug treatment. When post-drug thresholds had stabilized, subjects were sacrificed and their cochleas stained, embedded in plastic, microdissected, and viewed with phase contrast microscopy to permit examination of the cochlear tissue. Post-drug data suggest that frequency discrimination at a high frequency is unaffected by a 40- to 45-dB sensorineural hearing loss, considerable hair cell damage, and the resultant disruption of the cochlear micromechanics. The data, in concert with previously published reports, suggest that FDLs may be less affected by a high-frequency sensorineural hearing loss than by a low-frequency sensorineural hearing loss.

Amikacin↗
PubMed2000

Antibody interactions with the capsule of Cryptococcus neoformans.

Monoclonal antibodies to the encapsulated fungus Cryptococcus neoformans produce different immunofluorescence (IF) patterns after binding to the polysaccharide capsule. To explore the relationship between the IF pattern and the location of antibody binding, two immunoglobulin M (IgM) monoclonal antibodies (MAbs) (12A1 and 13F1) that differ in protective efficacy and IF pattern and one protective IgG1 MAb (2H1) were studied by IF and electron microscopy (EM). Fixing C. neoformans cells in lung tissue for EM resulted in significantly better preservation of the capsule than fixing yeast cells in suspension. The localization of MAbs 12A1 and 13F1 by immunogold EM differed depending on whether the MAb was bound to cells in cut tissue sections embedded in plastic or to cells in solution. In cut tissue sections, MAbs 12A1 and 13F1 bound throughout the capsule, whereas in solution both MAbs bound near the capsule surface. To investigate whether antibody binding to the C. neoformans capsule affected the binding of other primary or secondary reagents, various combinations of MAbs 12A1, 13F1, and 2H1 were studied by direct and indirect IF. The IF pattern and location of binding for MAbs 12A1, 13F1, and 2H1 varied depending on the presence of other capsule-binding MAbs and the method of detection. The results show that (i) binding of MAbs to the C. neoformans polysaccharide capsule can modify the binding of subsequent primary or secondary antibodies; (ii) the IgM MAbs bind primarily to the outer capsule regions despite the occurrence of their epitopes throughout the capsule; and (iii) MAb 2H1 staining of newly formed buds is reduced, suggesting quantitative or qualitative differences in bud capsule.

Animals↗
PubMed1973

Ultrastructure of the cell wall and cytoplasmic membrane of gram-negative bacteria with different fixation techniques.

The ultrastructure of the cytoplasmic membrane and cell wall of two strains of Escherichia coli, Proteus morganii, P. vulgaris, Acinetobacter anitratum, Moraxella lacunata, Erwinia amylovora, Acinetobacter sp., and of a plant pathogen, unclassified gram-negative, fixed by the Ryter-Kellenberger procedure, was found to be significantly affected by the use or omission of the uranyl postfixation included in that procedure, and by the presence or absence of calcium in the OsO(4) fixative. The omission of the uranyl treatment results in a less clear profile of both the outer membrane of the cell wall and of the cytoplasmic membrane. The observation of these two membranes is further limited when both uranyl and calcium are omitted. The R-layer and the material covering the surface of the cell wall appear more distinct when the uranyl postfixation is not used. Evidence is given suggesting that the influence of uranyl and calcium ions on the appearance of the outer and cytoplasmic membranes would be primarily due to their action as fixatives, whereas the influence of uranyl on the appearance of the R-layer would be due to a direct action on the peptidoglycan component of this layer. When uranyl acetate is used as a section stain after the embedding in plastic, it improves the observation of the R-layer. In this case, a well contrasted R-layer is consistently observed in all strains studied, provided that the postfixation has been omitted. The frequent difficulty in clearly observing the R-layer in many published micrographs probably results from the common use of uranyl postfixation.

Alcaligenes↗
PubMed1962

MORPHOLOGY OF SPORE DEVELOPMENT IN CLOSTRIDIUM PECTINOVORUM.

Fitz-James, Philip C. (University of Western Ontario, London, Ont., Canada). Morphology of spore development in Clostridium pectinovorum. J. Bacteriol. 84:104-114. 1962-The process of spore formation in Clostridium pectinovorum was followed by phase-contrast microscopy and by thin-section electron microscopy employing a polyester plastic for embedding. The development of the forespore membrane was found to be similar to that already described for the genus Bacillus, being, in addition, accompanied by considerable cell enlargement. The cortex, as in the bacilli, was found between the apposed layers of the double forespore membrane. The spore coat was laid down in the narrow zone of cytoplasm peripheral to the outer forespore membrane. As these layers formed, striking changes occurred in the fine structure of the spore nuclear material, mesosomes and ribosomes, reflecting the marked alterations in physical environment known to occur in a developing spore.

Journal Article↗
PubMed2004

Response of very small (2 mm) porcine coronary arteries to balloon angioplasty and stent implantation.

OBJECTIVE: To investigate the response of very small coronary arteries to stent deployment and balloon angioplasty. SETTING: Normal porcine coronary arteries. METHODS: 24 pigs underwent intervention to two main coronary arteries, in segments 2.0 mm in diameter, with balloons whose diameter was 2.5 mm at standard pressure. Twelve arteries received a BiodivYsio small vessel (SV) stent; 12 an NIR SV stent; 12 standard BiodivYsio stent, and 12 balloon only. The arteries were harvested at 28 days, fixed, embedded in plastic, and cut and ground in cross section. The injury score and histomorphometry were assessed. RESULTS: The BiodivYsio SV stent was associated with 20% less injury (p = 0.16), a 30% larger lumen (p = 0.13), and a 25% smaller neointima (p = 0.03) than the NIR SV stent, despite identical oversize. The standard BiodivYsio stent exhibited less recoil but 29% greater injury (p = 0.01), 59% more neointima (p = 0.00), and 18% less lumen (p = 0.27) than the BiodivYsio SV. Of all interventions, balloon only was associated with little injury, little neointima, major vessel shrinkage, and the largest lumen. CONCLUSION: Despite uniform oversize dilatation, both injury and response varied widely in very small porcine coronary arteries, depending on whether a stent or balloon was used, the stent design, and the number and/or thickness of struts. The response to different stent designs is considerable and is related to the degree of injury.

Angioplasty, Balloon↗
PubMed1991

Spinous injury caused by a sea urchin.

A bather on holiday in Kenya injured a finger on a spiny marine creature living on the sea bed. A skin biopsy specimen from the injured finger contained several black spines about 0.5 mm in diameter and up to 1.5 cm in length. Spines removed from the specimen were embedded in plastic resin to facilitate transverse sectioning. Light microscopical examination using crossed polarisers showed an ornate symmetrical structure brightly illuminated against a dark background. These features are characteristic of sea urchin (Echinoderm) spines which are composed of ornately formed calcite crystals covered by an epithelium. The spines of sea mice, on the other hand, are chitinous in nature; they are also much finer and lack the ornate symmetry of sea urchin spines.

Animals↗
PubMed1991

Structure of a human pulmonary acinus.

The structure of the human pulmonary acinus has been described infrequently. The aim of the study was to determine the branching pattern of respiratory bronchioles and alveolar ducts in a human acinus from the peripheral part of the lung, where space constraints may have affected airway branching patterns. The lungs were obtained from an 18 year old victim of a motor vehicle accident and fixed in inflation under a pressure of 25 cm H2O. A block was cut from the lower edge of the right lower lobe and embedded in plastic. Serial sections were cut and the branching pattern of airways subtended by a terminal bronchiole were followed. The acinus was bounded on two sides by pleura and on the remaining sides by connective tissue septa. The terminal bronchiole divided into two respiratory bronchioles, each of which gave rise to four systems of alveolar ducts. Between successive systems of alveolar ducts the respiratory bronchioles continued as single airways, becoming progressively more alveolated towards the periphery but not subtending further branches of respiratory bronchioles. The duct systems became less complex towards the periphery, near to the edge of the lung. The total volume of the acinus was similar to that found in previous studies. This branching pattern has not been described previously in a human acinus.

Adolescent↗
PubMed2004

Proximal airway mucous cells of ovalbumin-sensitized and -challenged Brown Norway rats accumulate the neuropeptide calcitonin gene-related peptide.

Mucous cell hypersecretion and increased neuropeptide production play a role in the exacerbation of symptoms associated with asthma. The source of these neuropeptides have been confined to the contributions of small afferent nerves or possibly neuroendocrine cells. We tested the hypothesis that repeated exposure to allergen would alter the sources and abundance of neuropeptides in airways. Right middle lobes from rats (8 wk old) exposed to 2.5% ovalbumin (OVA) for five episodes (30 min each) or filtered air were inflation fixed with paraformaldehyde. The lobes were dissected to expose the airway tree, permeabilized with DMSO, and incubated in antibody to rat calcitonin gene-related peptide (CGRP), followed with a fluorochrome-labeled second antibody. CGRP-positive structures were imaged via confocal microscopy. Airways were later embedded in plastic and sectioned for cell identification. In animals challenged with OVA, CGRP-positive cells, not neuroendocrine or neuronal in origin (confirmed by a lack of protein gene product 9.5 signal), were recorded along the axial path. In section, this fluorescent signal was localized to granules within epithelial cells. Alcian blue/periodic acid-Schiff staining of these same sections positively identify these cells as mucous cells. Mucous cells of animals not challenged with OVA were not positive for CGRP. We conclude that episodic allergen exposure results in the accumulation of CGRP within mucous cells, creating a new source for the release of this neuropeptide within the airway.

Allergens↗
PubMed1993

Physical and cytochemical properties of neutrophils activated in situ in the lung during ZAP infusion in sheep.

Increased retention of activated neutrophils in the lungs contributes to endothelial cell injury. However, characterization of the morphological changes that occur in neutrophils during activation in the pulmonary microcirculation has not been fully determined in vivo. Therefore, the present study was designed to determine structural and cytochemical properties of neutrophils in situ in pulmonary arterioles and alveolar capillaries during the infusion of zymosan-activated plasma (ZAP) or plasma (control) in anesthetized sheep. Quantitative morphological methods showed that ZAP infusion caused significant retention of neutrophils in alveolar capillaries [2.19 +/- 0.40 (SD) x 10(8) neutrophils/ml of capillary blood volume] and pulmonary arterioles (1.02 +/- 0.46 x 10(8) neutrophils/ml of arterial blood volume) compared with plasma infusion (1.03 +/- 0.15 and 0.30 +/- 0.10 x 10(8) neutrophils/ml, respectively; P < 0.05). Harmonic mean diameter of ZAP-activated neutrophils in situ (7.19 +/- 0.44 microns) was significantly greater than the diameter of neutrophils in plasma-treated sheep (6.29 +/- 0.17 microns; P < 0.05). Neutrophil cross-sectional area (54 +/- 3 microns2) and volume (248 +/- 27 microns3) in situ in alveolar capillaries were also significantly greater in ZAP-treated sheep than in control sheep (41 +/- 4 microns2 and 184 +/- 9 microns3, respectively; P < 0.05). Similarly, microvascular neutrophils in ZAP-treated sheep were vacuolated and elongated, filamentous actin was redistributed peripherally, and the cells were degranulated. We conclude that during ZAP infusion, neutrophils become enlarged and degranulated in pulmonary microvessels, especially in alveolar capillaries. The structural and cytochemical changes that occur are consistent with the hypothesis that neutrophil activation is accompanied by alterations in neutrophil physical properties, alterations that may facilitate retention and contribute to endothelial cell injury.

Actins↗
PubMed1993

Assessment of methacholine-induced airway constriction by ultrafast high-resolution computed tomography.

Assessment of changes in airway dimensions during bronchoconstriction is conventionally based on measurements of respiratory mechanics. We evaluated the efficacy of ultrafast high-resolution computed tomography (UHRCT) to directly determine the dynamic changes in cross-sectional area (CSA) of airways in response to methacholine (MCh). UHRCT scans were obtained at functional residual capacity before (baseline) and after intravenous bolus injections of MCh (10(-8.5)-10(-7.0) mol/kg) to seven mechanically ventilated pigs. Changes in CSA of bronchi of varying baseline size (1-10 mm diam) were determined by using a customized image processing software package (VIDA) based on a user-directed computer-adjusted edge-finding algorithm. MCh induced dose-dependent decreases in CSA, which were paralleled by increases in airway opening pressure at higher doses of MCh; at lower doses of MCh, decreases in CSA of smaller airways were detected without concomitant changes in airway opening pressure. Changes in CSA were heterogeneous and variable, especially in the smaller airway ranges. The results of the present study support the concept that UHRCT can be used in conjunction with bolus challenges to effectively determine dose-response changes in airway caliber in both large and small airways. This technique provides data that may not be reflected by conventional lung function measurements and, hence, is a useful tool to study airway reactivity.

Animals↗