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Biomedical subjects

L E Ericson

Publications and source records attributed to L E Ericson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Experience with percutaneous titanium implants in the head and neck: a clinical and histological study.

Percutaneous implants have been associated with numerous problems. However, by using skin-penetrating, bone-anchored titanium implants, developed by Professor Brånemark at the Department of Anatomy, University of Göteborg, good long-term results have been observed. These implants have been in clinical use for anchorage of bone-conducting hearing aids and facial prostheses since 1977 and 1979, respectively. The total number of implants is approximately 700. Less than 4% of the observations have shown significant irritation. Biopsies from 33 patients were collected for histological studies. In the irritated skin there was an increased number of inflammatory cells, mainly polymorphonuclear cells, B-cells, and plasma cells but not T-cells. This suggests a response directed against exogenous agents rather than an allergic reaction against the implant per se.

Ear, External↗
PubMed1989

Soft-tissue response to clinically retrieved titanium cover screws reimplanted in the rat abdominal wall.

Clinically retrieved titanium implant cover screws (Brånemark implant system), rinsed in saline or subjected to ultrasonic cleaning and sterilization, as well as unused sterile screws were studied by scanning electron microscopy and implanted in the rat abdominal wall for 6 weeks. Irrespective of cleaning procedure, the heads of the clinically retrieved screws were covered by numerous contaminants not present on the unused screws. The reimplanted screws elicited a different tissue response than the unused screws. The tissue response to the contaminated screws was characterized by a significantly thicker fibrous capsule and by a significantly larger number of macrophages located close to the implant. Moreover, judging from their ultrastructure, studied with transmission electron microscopy, the macrophages appeared to be in a more active state when compared to those located adjacent to unused screws.

Animals↗
PubMed1989

Leukocyte migration in synovial tissue. Leukocyte distribution, orientation, and migratory pattern after immune complex deposition in rabbit knee joints.

Complement-activating bovine serum albumin (BSA)-anti-BSA immune complexes (ICs) were injected into rabbit knee joint cavities; the contralateral control joint was injected with BSA together with normal rabbit serum. The migration of leukocytes from the synovial venules into the joint cavity was analyzed with light microscopy (LM), scanning (SEM) and transmission (TEM) electron microscopy. EM autoradiography was used to study the endocytosis of ICs by leukocytes. The shape, orientation, and distribution of migrating polymorphonuclear granulocytes (PMNGs) were analyzed by LM morphometry. PMNGs accumulated in the joints injected with ICs. The peak of the number of PMNGs in the synovial tissue was reached after 4 hours, in the joint cavity after 6 hours. PMNGs in the synovial tissue were concentrated in the intimal layer. Migrating PMNGs were polarized, as judged by the ratio between the long (D max) and short (D min) axes of the cells. There was a close association between the migrating PMNGs and the collagen fibers. The morphometric data showed that the nonflattened, cylindrically-shaped PMNGs were oriented along the collagen bundles, running parallel to the synovial surface, and did not migrate in the straight direction of a theoretic leukotactic gradient originating in the joint cavity after IC deposition. SEM and TEM showed that the PMNGs were aligned along the collagen fibers and interacted activity with the collagen by pseudopods and cytoplasmic projections. EM autoradiography showed that the PMNGs in the joint cavity had ingested 125I-labeled ICs and were degranulated. In contrast, the PMNGs within the synovial membrane did not show any signs of IC endocytosis or any apparent degranulation. Synovial type A cells were found to contain ICs. This study indicates that the response of PMNGs in IC-induced synovitis consists of two distinct phases: an initial, mainly migratory phase in the synovial membrane where the PMNGs appear to use the collagen fibres as a climbing framework, and a second phase, in the joint cavity, characterized by PMNG metabolic activation, endocytosis of ICs, and degranulation. The apparent inability of PMNGs in the synovial membrane to ingest ICs and become degranulated might be due to not only concentration differences of ICs and leukotactic factors between the joint cavity and the synovial tissue but also might be related to the apparently active interaction with collagen.

Animals↗
PubMed1988

Electron-microscopic immunocytochemistry of 5-hydroxytryptamine in the ascidian endostyle.

The cellular and subcellular distribution of serotonin (5-hydroxytryptamine, 5-HT) in the endostyle of three species of ascidians, Ciona intestinalis, Corella parallelogramma, Ascidia mentula, was studied by light- (immunoperoxidase) and electron-microscopic (immunogold) immunocytochemistry. At the light-microscopic level 5-HT-like immunoreactivity (5-HT-LI) was exclusively found in cells located in the lateral portion of the endostyle, between zone 7, known to have iodinating capacity, and zone 8, which consists of ciliated cells. At the electron-microscopic level, the 5-HT-immunoreactive cells were found to correspond to cells containing polymorphous, dense granules, 100-300 nm in diameter. The granules were located in the supranuclear cytoplasm facing the endostyle lumen as well as in the infranuclear cytoplasm facing the extracellular space. Quantification showed that the 5-HT-LI was considerably higher (13-67 times) in cytoplasmic areas containing granules as compared to areas devoid of granules. Most, but not all, of the 5-HT-LI was associated with the dense core of the granules. In conclusion, serotonin-containing cells are located in the peripheral portion of the endostyle, between zones 7 and 8. Serotonin is stored in cytoplasmic granules that are present both in the apical and basal cytoplasm. This suggests the possibility that the cells are bipolar and secrete serotonin both in a basal direction to the extracellular space, and in an apical direction to the pharyngeal lumen.

Animals↗
PubMed1988

Iodine binding and peroxidase activity in the endostyle of Salpa fusiformis, Thalia democratica, Dolioletta gegenbauri and Doliolum nationalis (Tunicata, Thaliacea).

The protothyroid region in the endostyles of four species of tunicates was examined by means of autoradiography and cytochemistry, at both the light and electron-microscopic levels. To reveal the primary binding site for iodine, autoradiography was carried out on endostylar tissue from animals that had been incubated with high activity 125I over a short period of time. The specific iodine binding enzyme, a peroxidase, was traced by its reaction with DAB. In accordance with previous findings, the iodine-binding cells proved to be the same as those containing the peroxidase. There were also strong indications of a secondary uptake of iodinated compounds and subsequent release into the body fluid. Together with the ultrastructural features, the data provided strong evidence indicating that these cells constitute a protothyroid region, which partly functions as an endocrine organ, possibly homologous with the vertebrate thyroid gland. Since the number of zones varied between the species, the numeration of the protothyroid region also varied. However, in all the examined endostyles, the protothyroid region was seen to be situated dorsolaterally to the glandular regions of the endostyle concerned with food capture.

Animals↗
PubMed1988

Plasma membrane shedding and colloid vacuoles in hyperactive human thyroid tissue.

The ultrastructural appearance of colloid vacuoles, considered to be a typical sign of hyperactivity in the human thyroid gland, was studied in human thyroid tissue transplanted to nude mice and in human thyroid tissue fixed directly after surgical removal in patients with thyrotoxicosis. Transplanted normal thyroid tissue and toxic diffuse goiter (TDG) tissue was fixed by vascular perfusion with glutaraldehyde 5 or 12 weeks after transplantation. Light microscopic quantification showed that daily injections for 2 weeks of a gamma globulin fraction of patient sera containing thyroid-stimulating immunoglobulins (TSI) greatly increased the number of colloid vacuoles in both types of transplants. The vacuoles were mainly located in the periphery of the follicle lumen, giving the colloid a scalloped appearance. Electron microscopy of TSI-exposed tissue revealed, in addition to colloid vacuoles, the presence of large amounts of membrane material in the follicle lumen. Only sparse amounts of intraluminal membrane material were present in controls. The colloid vacuoles were almost invariably associated with such membrane material, which lined the border between the vacuole and the surrounding colloid. The intraluminal material consisted of spherical and elongated formations, each structure limited by a triple-layered membrane and often containing a dense interior. The elongated structures were often of the same dimensions as microvilli. The apical surface of follicle cells in TSI-exposed tissue expressed numerous microvilli, of which many showed a similar dense interior as the intraluminal membrane structures. The intraluminal membranes frequently showed, like the apical plasma membrane of the follicle cells, a positive reaction for peroxidase. Organelles, such as mitochondria, lysosomes or rough endoplasmic reticulum, were not encountered among the intraluminal membrane structures. These observations indicate that the intraluminal membrane material is derived from the apical plasma membrane of the follicle cells, presumably by shedding of microvilli. A similar association between colloid vacuoles and membrane material was also found in thyroid tissue from patients with thyrotoxicosis fixed directly at operation. It is suggested that the presence of membrane material in the follicle lumen precipitates the formation of colloid vacuoles in hyperactive thyroid tissue. The possible involvement of intraluminal membrane material in the development of microsomal autoantibodies in Graves' disease, i.e. exposure and presentation of thyroid microsomal antigen (identical to thyroperoxidase) to the immune system, is discussed.

Animals↗
PubMed1988

Hollow implants in soft tissues allowing quantitative studies of cells and fluid at the implant interface.

In order to study the early cellular response in the fluid phase found close to implants in soft tissues, an experimental method using a hollow implant was developed. The fluid present in an interior chamber communicating with the exterior of the implant was analysed. Polymorphonuclear granulocytes (PMNGs) were predominant during the study (1-9 days). In titanium implants a slight increase in cell numbers with time was noted, whereas in polytetrafluoroethylene (PTFE) implants, a sharp increase in cell numbers was observed. Preliminary studies showed that sufficient amounts of fluid and cells could be retrieved for analysis of protein composition and inflammatory cell activation.

Animals↗
PubMed1988

Forskolin-induced elevation of cyclic AMP does not cause exocytosis and endocytosis in rat thyroid follicle cells in vivo.

Using a newly developed infusion technique, the in vivo effects of forskolin and dibuturyl cyclic AMP (dbcAMP) on exocytosis and endocytosis in thyroid follicle cells were studied in thyroxine-treated rats and mice. Reactants were selectively infused via the superior thyroid artery to one thyroid lobe. The contralateral lobe served as a control. In the rat, a supramaximal i.v. dose of thyrotropin (TSH, 500 mU) induced a slight increase in thyroidal tissue levels of cyclic adenosine monophosphate (cAMP) while TSH 50 mU i.v. had no effect on cAMP levels. On the other hand both doses of TSH stimulated exocytosis, signified by a decrease in the number of exocytotic vesicles and endocytosis, signified by the appearance of pseudopods and colloid droplets. Selective thyroid infusion of dbcAMP (5 mM) or forskolin (25 microM), which induced a 10-fold increase in thyroid cAMP levels, did not induce any morphological sign of exocytosis or endocytosis in the follicle cells. The morphological response to TSH given i.v. was quantitatively unaltered by simultaneous infusion of forskolin. In contrast to the findings in rats, infusion of forskolin and dbcAMP in mice induced endocytosis. In conclusion, our findings in the mouse are in agreement with earlier studies in this and other species, indicating that cAMP mediates the effects of TSH on endocytosis and probably also on exocytosis. In contrast, our observations in the rat thyroid in vivo lead to the conclusion that cAMP is not the main intracellular mediator of exocytosis and endocytosis in this species. This conclusion is at variance with previous reports, mostly from in vitro studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

A method for selective infusion in the thyroid artery of the rat and mouse.

A technique for in vivo infusion in the superior thyroid artery in rats and mice was developed and evaluated. The influx catheter is inserted in retrograde direction into the superior carotid artery. The infusate mixed with blood is directed exclusively to the thyroid lobe via the superior thyroid artery. The thyroid isthmus is divided and the other lobe serves as a control. Thyroid ultrastructure was unaltered after infusion for at least 4 h and the follicle cells displayed a normal morphological response to TSH. Electron microscopical autoradiography (125I, [3H]leucine) was performed using 20-80 times less label as compared with iv administration. Infusion of forskolin, a stimulator of adenylate cyclase, increased the intrathyroidal cyclic AMP levels about 10-fold. Infusion of the ionophore monensin yielded typical dilations of Golgi cisternae as well as reduced secretion of newly synthesized protein into the follicle lumen. The arterial infusion technique developed is useful when in vitro methods or systemic administration of substances are unsuitable. The technique permits selective administration of small amounts of experimental substances to the thyroid in high concentrations.

Animals↗
PubMed1987

Immunocytochemical localization of aminopeptidase N on the cell surface of isolated porcine thyroid follicles.

The ultrastructural location of aminopeptidase N on the cell surface of isolated porcine thyroid follicle cells was studied with immunocytochemistry using antibodies against intestinal aminopeptidase N and protein A-colloidal gold. Gold particles, indicating immunoreactivity, were selectively attached to the apical cell surface. Occasionally, there was a sparse labelling of the basal cell surface. In follicles kept at 4 degrees C most gold particles at the apical cell surface appeared as clusters, with each gold particle situated at a constant distance of about 20 nm from the membrane surface. The gold particles were concentrated on the membranes of microvilli, in comparison to the smooth (intermicrovillar) portions of the apical plasma membrane. In follicles incubated at 37 degrees C for 5-180 min gold particles were slowly internalized by predominantly smooth-surfaced micropinocytic vesicles and subsequently appeared in colloid droplets and lysosomes. Gold particles were not observed in Golgi cisternae. TSH did not appear to influence the rate of internalization. TSH-induced pseudopods were unlabeled. Our electron-microscopic observations confirm previous immunofluorescence-microscopic evidence that aminopeptidase N is selectively expressed in the apical plasma membrane domain in the thyroid follicle cell. Furthermore, aminopeptidase N appears to be distributed in microdomains within the apical plasma membrane. Earlier indications of molecular differences between the pseudopod membrane and the apical plasma membrane proper are further emphasized.

Aminopeptidases↗
PubMed1987

Bipolarity of duodenal enterochromaffin cells in the rat.

Enterochromaffin cells of the rat duodenum have been studied immunocytochemically by use of a specific antiserum to serotonin. At the light-microscopic level serotonin immunoreactivity was observed in enterochromaffin cells located in the epithelium of the duodenal mucosa. Most of the serotonin-immunoreactive material was localized to the basal portion of the enterochromaffin cells, but small amounts of immunoreactive material were regularly observed in the apical portion. At the electron-microscopic level serotonin immunoreactivity in enterochromaffin cells was found to be concentrated over the dense cores of the cytoplasmic granules. The majority of these granules was located in the basal cytoplasm of the enterochromaffin cells, but serotonin-immunoreactive granules were also observed in the apical cytoplasm immediately beneath the microvilli. These observations indicate that duodenal enterochromaffin cells are bipolar and that they secrete serotonin both basally, to the circulation, and apically, to the gut lumen. Rat duodenal enterochromaffin cells thus appear to have an exocrine as well as an endocrine function.

Animals↗
PubMed1987

Effects of thyroid stimulating immunoglobulin on function and morphology of xenotransplanted toxic diffuse, toxic nodular and normal thyroid tissue.

In order to examine the properties of human thyroid tissue, toxic diffuse goiter (TDG), toxic nodular goiter (TNG) and normal thyroid tissue were transplanted to nude mice. Starting 3 and 10 weeks after the transplantation the mice were given 14 daily injections of control serum or serum containing thyroid stimulating immunoglobulin (TSI). The uptake and release of 125I were repeatedly measured externally. The uptake and unstimulated release of 125I was lowest in TDG transplants, highest in TNG transplants, and intermediate in transplants of normal thyroid tissue. The findings were similar at both 3 and 10 weeks. Injections of TSI reduced the biological half-time of the tracer in TDG and normal transplants, but had no significant effect on TNG transplants. Light and electron microscopic studies showed that hyperplastic TDG tissue underwent involution after transplantation, whereas TNG and normal thyroid tissue remained unchanged. Injection of TSI reactivated TDG tissue; morphometry showed that the absolute and relative volumes of the follicle cells were more than doubled, with a corresponding decrease in the volume of the follicle lumen, and mitotic figures were common. Similar findings were seen in normal transplants, whereas the effect of TSI on TNG tissue was less pronounced. In summary, our observations show that serum from a patient with Graves' disease stimulated iodine release and induced follicle cell hyperplasia and probably also follicle cell multiplication in transplanted normal and TDG tissue, but had a lesser effect on TNG tissue.

Animals↗
PubMed1987

Immunoelectron microscopic studies on the cell surface location of the thyroid microsomal antigen.

The cell surface location of the thyroid microsomal antigen was studied by immunoelectron microscopy. Isolated, open human thyroid follicles were incubated with patient sera containing high titers of microsomal autoantibodies. Cell surface-bound antibodies were detected by the immunogold technique using IgG-coated colloidal gold particles (10 or 15 nm). Immunocytochemical incubations were performed at 4 degrees C. Gold particles were concentrated at the apical cell surface of the follicle cells, while the basolateral cell surface was almost completely unlabelled. Quantitative evaluation of four experiments with follicle cells prepared from different patients showed that about 90% of the gold particles at the apical cell surface was associated with microvilli and that the concentration of gold particles at the microvillus membrane was, although with great intercellular variation, several times higher than that at smooth portions of the apical plasma membrane. This suggests that the microsomal antigen is organized in microdomains in the apical plasma membrane. In follicles labelled immunocytochemically at 4 degrees C and then incubated at 37 degrees C, gold particles were slowly internalized. The particles appeared in smooth and coated pits of the apical plasma membrane as well as in vesicles, vacuoles and lysosomes in the apical part of the cytoplasm. Membranes of TSH-induced pseudopods were always unlabelled. Our observations indicate that thyroid microsomal antigen immunoreactivity is present in the apical but not in the basolateral plasma membrane. The antigen with bound antibodies is internalized by micropinocytosis but not by macropinocytosis. The selective location of bound microsomal antibodies at the apical plasma membrane and their absence from the membrane of TSH-induced pseudopods are compatible with the idea that the microsomal antigen and thyroperoxidase are identical.

Antigens, Surface↗
PubMed1987

Vascularization of normal human thyroid tissue transplanted to nude mice.

The vascularization of normal human thyroid tissue transplanted to nude, athymic mice was examined by light, electron microscopy and autoradiography after continuous infusion of 3H-thymidine during 2, 4 and 6 days after transplantation. Labelled vascular sprouts were found in the surrounding host connective tissue after 2 days, in between peripheral follicles after 4 days and in central parts of the transplants after 6 days. The autoradiographic observations indicate that the sprouts originated from the surrounding host tissue. The amount of sprouts increased up to a maximum after 2 weeks of transplantation. At this time large interfollicular areas were occupied by sprouts. At later observations (3-5 weeks) sprouts occurred together with typical fenestrated capillaries. After 7 weeks all sprouts had differentiated into mature vessels. Our observations suggest that the transplanted thyroid tissue induces the formation of vascular sprouts in the surrounding host connective tissue. The sprouts then penetrate and vascularize the thyroid tissue.

Animals↗
PubMed1987

An improved immunocytochemical method for subcellular localization of serotonin in rat enterochromaffin cells.

Serotonin-like immunoreactivity (5-HT-LI) has been localized at the ultrastructural level in enterochromaffin (EC) cells of rat gastrointestinal tract. Ultra-thin sections of tissues embedded in epoxy resin were incubated with 5-HT antisera and antibody binding sites were visualized with protein A-gold. Three different antisera were compared and were shown to require different fixation regimens for optimal preservation of 5-HT-LI. For one antiserum, tissues fixed in glutaraldehyde and osmium tetroxide could be used to demonstrate 5-HT-LI in EC cells. Immunocytochemical localization of 5-HT can thus be performed with good ultrastructural preservation of tissues. Quantitative evaluation of the intracellular distribution of 5-HT-LI was performed on EC cells from antrum, duodenum, and proximal colon, fixed in glutaraldehyde only. In all three locations, the majority of the gold particles (90%) in EC cells were localized over the dense core of the secretory granules, while a minor fraction (10%) were localized in parts of the cytoplasm devoid of granules. In EC cells fixed in glutaraldehyde and post-fixed in osmium tetroxide, 5-HT-LI was reduced by about 85%, although intracellular distribution was essentially the same as in cells fixed in glutaraldehyde alone. The results indicate that 5-HT in EC cells is stored mainly in secretory granules, with a small fraction of 5-HT being localized outside the granules.

Animals↗
PubMed1987

3,4-Dihydroxypyridine: a potential antithyroid drug.

3,4-Dihydroxypyridine (3,4-DHP), a goitrogenic derivative of the plant amino acid mimosine, has no SH-group, in contrast to conventional antithyroid agents such as methimazole (MMI) and propylthiouracil (PTU). The current in vitro study shows that 3,4-DHP, like MMI and PTU, inhibits iodination of human thyroglobulin and interferes with mitogenic activation of human lymphocytes. This, together with a very low murine bone marrow toxicity, probably related to the absence of an SH-group, makes 3,4-DHP a potential antithyroid drug.

Antithyroid Agents↗
PubMed1987

Titanium implants in rabbit knee joints.

The subchondral bone, cartilage, and synovial tissue adjacent to nonalloyed titanium screws were morphologically evaluated 2, 4, and 6 weeks after insertion in rabbit knee joints. The titanium screws were in direct contact with the surrounding bone. Two weeks postoperatively, bone resorption, as well as formation of new bone on the titanium surface, was evident. The observed inflammatory process was transient, and the amount of bone within the screw threads increased progressively with time. The articular cartilage regenerated and covered the titanium screws. Synovial tissue also regenerated and covered the screws when inserted into a noncartilaginous area of the joint. These findings, together with recent findings in soft tissues, indicate that titanium provides an inert surface for the proliferation of differentiating tissues in vivo. These data, supported by the observation that no inflammation was present in the synovial tissue, suggest that nonalloyed titanium can be used safely intraarticularly.

Animals↗