Subcellular localisation of the middle and large T-antigens of polyoma virus

The distribution of two of the polyoma virus early proteins (the large and middle T-antigens) in lytically infected mouse cells and transformed rat cells has been investigated by indirect immunofluorescence and immuno-electron microscopy using well-characterised monoclonal antibodies. By these techniques, the viral large T-antigen was found almost exclusively in the nucleus, sometimes in association with nuclear pores, but never in the nucleolus. In lytically infected, but not transformed cells, fluorescence was detected in discrete areas ('hot spots') within the nucleus and, in a minor population of lytically infected cells, cytoplasmic immunoreactive material was observed. The viral middle T-antigen was found in association with most cytoplasmic membranes and in the majority of cells mainly in the endoplasmic reticulum. Only a fraction of the staining was observed in the plasma membrane and no staining in the nucleoplasm was observed. The data suggest that the site of action of the major transforming activity of polyoma virus need not be at the plasma membrane. Functions associated with the viral antigens are discussed in terms of their subcellular distributions within cells.

Nasal mucosa changes after acute and long-term exposure to dicumylperoxide. An experimental study on animals

Workers exposed to dicumylperoxide at a chemical plant had crusting and increased occurrence of visible superficial mucosal vessels in the anterior part of the nasal septum. To elucidate the pathogenesis of their symptoms we examined rabbits after acute and long-term experimental airway exposure to dicumylperoxide. An increased amount of mucus containing red blood cells were seen after one hour exposure, as were many club-shaped or distorted cilia. Areas lacking cilia but still covered with microvilli and with goblet cells appeared after a week. After one month's exposure scattered islands with metaplastic, non-ciliated cells were observed and many of the ciliated and microvilli-covered cells, not only the cilia per se, appeared distorted. Goblet cells, scarce in the controls, were observed in increased frequency. Blood vessels with thick, non-fenestrated endothelium were observed in increased frequency and remained two months after the exposure. Free radical scavengers seem to reduce the extent of damage supporting our hypothesis of peroxides as damaging agent.

Acute synovitis induced by preformed immune complexes

The morphology of acute immune complex (IC) elicited synovitis in rabbit knee joints was studied, as well as IC-induced leukocyte activation in vivo and in vitro. Acute synovitis was induced by intra-articular injection of in vitro preformed, complement activating bovine serum albumin (BSA)-anti-BSA IC. Within 30 min, migration of polymorphonuclear granulocytes (PMNGs) was observed. Scanning electron microscopy showed that adhering, apparently activated leukocytes were attached to the synovial lining, often forming clusters. Phagocytosis of IC was evident, as immunoglobulins were detected within the leukocyte cytoplasm by the direct immunofluorescence technique. At the peak accumulation of PMNGs, focal erosions of the synovial lining were observed. Later, monocytes and macrophages appeared and degenerated PMNGs were found, sometimes within the cytoplasm of large macrophages. Chemiluminescence experiments showed a maximum in vitro activation of leukocytes by complement activating IC formed near optimal precipitation proportions and in slight antigen excess, whereas IC in large antigen excess gave a smaller and later response.

Axoplasmic transport of thioredoxin and thioredoxin reductase in rat sciatic nerve

Thioredoxin and thioredoxin reductase were localized immunohistochemically in the rat sciatic nerve by immunofluorescence using specific rabbit antisera. Both proteins showed strong immunoreactivity in the cytoplasm of Schwann cells and at the nodes of Ranvier. The axoplasm of myelinated axons also showed a low, evenly distributed immunoreactivity for both proteins. A single or double crush of the nerve caused accumulation of immunoreactivity in dilatated axons both proximally and distally to the crush for up to 8 h. Local cooling of the nerve or subepineural injection of either colchicine or vinblastine prevented the accumulation indicating a role of microtubules. The results showed that thioredoxin and thioredoxin reductase are synthesized in nerve cell bodies and rapidly transported in axons both in anterograde and retrograde directions.

Intermediate filaments in cultured human pleomorphic adenomas. An immunohistochemical study

Primary cultures of 9 benign human pleomorphic adenomas were analyzed by immunofluorescence and antibodies against the different intermediate filaments and microfilaments. The cultured cells were also cytogenetically characterized by G- and C-banding techniques. The adenoma cells expressed at least three different classes of intermediate filaments, viz. prekeratin, vimentin and glial fibrillary acidic protein (GFA). No correlation between chromosomal pattern and intermediate filament expression was found. The frequency of cells stained for each of the different antibodies varied considerably among the tumours. Prolonged culturing appeared to induce a reduction of cells positive for prekeratin. This was probably a true loss of antigens and not an effect of overgrowth of stromal cells. It is concluded that the cells studied, on the basis of several criteria, are of neoplastic origin. This in vitro system appears to be well suited for further histogenetic studies on pleomorphic adenomas.

The nasal mucosa in immunodeficiency. Surface morphology, mucociliary function and bacteriological findings in adult patients with common variable immunodeficiency or selective IgA deficiency

Twenty-two adult patients suffering from common variable immunodeficiency (CVID) and sixteen patients with selective IgA deficiency were examined with regard to the mucocilliary function of the nose. The surface structures of the nasal mucosa, e.g. cell distribution and degree of destruction and metaplasia, were judged from scanning electron microscopy of nasal biopsies. Bacteria were isolated from nasopharyngeal swabs. The results of the clinical and morphological investigations were analysed with regard to the duration of the disease and possible benefit of adequate prophylaxis with immunoglobulin. It was found that patients with CVID had a slower mucociliary transport rate and more extensive mucosal damages than patients with selective IgA deficiency. Most likely these alterations were due to repeated infections as patients who had had few infections or adequate immunoglobulin prophylaxis (CVID patients) had better mucociliary function and showed less extensive mucosal changes. Potentially pathogenic bacteria in the nasopharynx were found in equal numbers in both patient groups.

Immunohistochemical localization of thioredoxin and thioredoxin reductase in adult rats

Rabbit antisera against homogeneous rat liver thioredoxin and thioredoxin reductase (NADPH-oxidized thioredoxin oxidoreductase, E.C. 1.6.4.5) were prepared and used for immunohistochemical analysis in adult rats. Immunoreactive thioredoxin and thioredoxin reductase were widely distributed in tissues and organs, but varied a lot between cell types. Generally, epithelial cells, neuronal cells and secretory cells, both exocrine and endocrine, showed high immunoreactivity whereas mesenchymal cells with exceptions showed low activity. Surface lining epithelial and keratinizing cells showed high activity. The immunofluorescence was localized in the cytoplasm of cells with enrichments at secretory granules, at the plasma membrane or in the subplasma membrane zone. Variations in secretory cells were seen related to feeding and starvation and to metabolic activity. The distribution of thioredoxin and thioredoxin reductase is compatible with function in thiol-disulfide interchange reaction related to protein synthesis, intracellular transport and different forms of secretion.

Interface analysis of titanium and zirconium bone implants

A thin layer of titanium or zirconium was evaporated onto the surface of a plastic implant which was then inserted in the rabbit tibial metaphysis for six months. The implants and surrounding bone were cut out en bloc and sectioned for phase contrast microscopy, scanning- and transmission-electron microscopy. The intact bone-to-metal interface in the case of titanium revealed a fibrous tissue-free boundary zone with a 200-400 A thick proteoglycan coat immediately adjacent to the titanium oxide. Thereafter collagen filaments were seen and, at approximately 1000 A from the interface, collagen bundles. The tissues surrounding the zirconium-coated implant consisted of a 300-500 A thick proteoglycan layer, followed by a zone with collagen filaments and collagen bundles, not closer to the zirconium oxide than a few thousand A.

Goblet cell number in the nasal mucosa relates to cell-mediated immunity in patients with antibody deficiency syndromes

Histopathological changes in the nasal mucosa were studied in biopsies from the inferior turbinate in 22 patients with common variable immunodeficiency (CVID) and 16 patients with selective IgA deficiency. Most patients with CVID had fewer goblet cells than the healthy controls (p less than 0.001), whereas patients with selective IgA deficiency often had manyfold increased numbers (p less than 0.001). The number of goblet cells showed a significant (p less than 0.001) relationship to the cell-mediated immune function. Patients with lowered cell-mediated immune function, as measured by in vivo and in vitro tests, showed reduced numbers or lack of goblet cells. These patients had an increased number of subepithelial, seromucous gland acini compared with healthy controls (p less than 0.01) and patients with selective IgA deficiency (p less than 0.05). The production of mucus may be a compensatory mechanism, participating in the protection of the mucosal surface of the antibody-deficient patient. The increase in the number of goblet cells, but not of subepithelial, seromucous gland acini seems dependent on the cell-mediated immune system.

Disulfiram is protective against postischemic cell death in the liver

The effect of the scavenger compound disulfiram (Antabus) on postischemic cell injury was investigated. Rats were subjected to 90 min of liver ischemia and 3 h of reperfusion. The extent of cell injury was evaluated morphologically by a dye exclusion test and a histochemical stain for calcium. It was found that pretreatment with disulfiram significantly reduced the number of injured cells compared to untreated controls.

Scanning electron microscopy of upper urinary tract tumors

Scanning electron microscopy (SEM) was performed on specimens from 16 patients with low-grade tumors, and 4 patients with benign lesions of the upper urinary tract. Pleomorphic microvilli could be seen at a low frequency on the majority of the tumor specimens as well as on surface cells of specimens from patients with inverted papilloma, fibroepithelial polyp, and hydronephrosis. The SEM appearance of the lining cells was similar whether the specimen was obtained from a patient with a tumor, or an inflammatory or proliferative lesion. Furthermore, pleomorphic microvilli were observed in five histologically normal bladders in which the covering cells had been rubbed off with a cold loop of a resectoscope. Pleomorphic microvilli are thus not morphologic markers of preneoplastic hyperplasia or tumor. It is likely that their presence merely reflects an increased rate of detachment of superficial epithelial cells which are replaced by cells from the deeper part of the epithelium. The demonstration of pleomorphic microvilli is therefore of questionable value in the preoperative diagnosis of tumors of the upper urinary tract and, consequently, their significance must be re-evaluated.

Structural and functional aspects of cells in the nasal mucociliary system

The regulation of the fluid balance of the mucus is important for a good function of the mucociliary system in the nose. The nasal glands and the goblet cells have been proposed to be the main source of fluid. Microvilli-equipped epithelial cells, ciliated and nonciliated, constituting 70% to 90% of the cells on the turbinates in the nose, are of importance for the regulation of the hydration of the mucus. These cells have the same characteristics as other fluid-secreting cells elsewhere in the body. They have microvilli, a terminal web, folding of the basolateral membrane, and numerous cell organelles. Blockage of the energy supply strongly reduces the fluid secretion.

Material thrombogenicity in central venous catheterization: a comparison between soft, antebrachial catheters of silicone elastomer and polyurethane

In order to compare two types of long, soft central venous catheters with the same stiffness, 39 silicone elastomer (SE) and 36 polyurethane (PU) catheters were inserted in 75 patients via basilic or cephalic veins punctured at the cubital fossa. Mean duration of catheterization was 10.5 days. Scanning electron microscopy revealed that the SE catheters to have a more uniform, but somewhat rougher surface topography than the PU catheters. The platelet adhesion in vitro to the SE catheters was four times higher than to the PU catheters. The incidence of clinical thrombophlebitis in the arm veins was 36% with the SE catheters, and 5.5% with the PU catheters (p less than 0.01). No significant differences were found between the SE and PU catheters regarding the number and size of radiologic thrombi in the peripheral and central veins, catheter occlusion rate, and platelet adhesion to the inner side of the catheter tip at withdrawal. Platelet adhesion in vivo correlated with the duration of catheterization in both groups of catheters. Mechanical trauma to the vein endothelium seems to be of vital importance in thrombus formation, but not in the induction of clinical thrombophlebitis.

Localization of ribonucleotide reductase in mammalian cells

The results of immunocytochemical studies using two different monoclonal antibodies against the M1 subunit of ribonucleotide reductase show an exclusively cytoplasmic localization of this subunit both in cultured MDBK and mouse 3T6 cells, and in cells from various rat tissues. By fluorescent light microscopy, there is a diffuse staining of the cytoplasm, while by electron microscopy the immunoreactive material appears to be associated with ribosomes. In the rat tissues, only actively dividing cells show M1-specific immunofluorescence revealing a strong correlation between the presence of protein M1 and DNA synthesis. Therefore M1 immunofluorescence could be used to study cell proliferation in normal, inflammatory or neoplastic tissue. A lesser variation in M1 staining is observed between individual cells in tissue culture, where most cells are positive, but neither here nor in the tissues examined are any cells with nuclear staining detected. We interpret our results to mean that in mammalian cells ribonucleotide reduction takes place in the cytoplasm and from there the deoxyribonucleotides are transported into the nucleus to serve in DNA synthesis.

Cytoskeletal disarrangement in rat intestinal epithelium after in vivo exposure to secretagogues

Cholera toxin (CT) and E. coli heat-labile enterotoxin (LT) induced hypersecretion in the small intestine, as did cytochalasin B and dibutyryl-cyclic AMP (DB-cAMP). The cytoskeleton in the apical part of the intestinal epithelial cells was disorganized after challenge with either of the four secretagogues, but not cholera B-subunit toxoid, as revealed by immunofluorescence microscopy using actin and the intermediate filament keratin as markers. Electron microscopic analysis confirmed the re-engagement of the terminal web and the appearance of short microvilli lacking most of their normally observed central core of actin filaments. Pretreatment with chloroquine prevented cytoskeletal disorganization as well as hypersecretion by CT, but not by cytochalasin B. A similar effect was achieved with chloroquine on CT-induced fluid secretion, while chlorpromazine inhibited the fluid response to cytochalasin B as well as to CT. The observed cytoskeletal re-engagement might be one of the reactions behind enterotoxic diarrhoea.

Intestinal adaptation to cyclic AMP-mediated hypersecretion induced by the heat-labile enterotoxin of Vibrio cholerae and Escherichia coli

Adaptation to cholera toxin (CT) and the heat-labile enterotoxin (LT) from E. coli is studied in vivo in the rat small intestine. Repeated peroral pretreatment with CT or LT induces protracted inhibition of the intestinal fluid response to these toxins. The CT-induced mucus release from intestinal goblet cells is not influenced by CT pretreatment and the binding of CT to the epithelium remains intact. However, the adenylate cyclase activity, which mediates CT and LT action, is repressed--as judged from the response of this enzyme to both CT, LT and prostaglandin E1. The results suggests that protection against CT and LT acquired in the gut is achieved by desensitization of the adenylate cyclase system.

Scanning electron microscopy of polypoid cystitis--a reversible lesion of the human bladder

Scanning electron microscopy was performed on forceps biopsies from 13 patients with catheter-associated polypoid cystitis. Pleomorphic microvilli, which varied considerably in appearance, were found on surface cells of all cases with polypoid cystitis. Practically all of the characteristics of pleomorphic microvilli assigned earlier to bladder tumor cells in humans were identified on specimens from patients with polypoid cystitis. Pleomorphic microvilli were not observed in the bladder biopsies from control patients. The appearance of pleomorphic microvilli was consistent with reversible lesions of the human bladder and they are not specific markers of pre-neoplastic hyperplasia or malignancy.

Internalization in vivo of cholera toxin in the small intestinal epithelium of the rat

The binding and internalization of cholera toxin (CT) into the intestinal epithelium were studied in vivo in rats. The distribution of CT was ascertained using immunofluorescence and by immunoenzyme-electron microscopy, with horse-radish peroxidase anti-CT antibodies as the conjugate. The toxin was rapidly bound and internalized into both epithelial and goblet cells; CT was evenly distributed on the microvilli at the bases of which it appeared in invaginations (coated pits). Though not found in nuclei, CT appeared intracellularly in coated vesicles, and dissolved in the cytoplasm where it was enriched at the terminal web. The basolateral membrane, except for the tight junctions, was outlined with CT; some staining also appeared in the basement membrane, in fibroblasts, macrophages and in the blood-vessel walls in the submucosa. The lysosomatotrophic agent chloroquine simultaneously inhibited CT-induced fluid secretion and intracellular distribution of CT in the cytoplasmic matrix, but not in the vesicles. The inhibitor of CT-action on adenylate cyclase, chlorpromazine, did not affect the cellular distribution of CT. Our results suggest that CT mainly is internalized by endocytosis into the intestinal epithelium. The toxin is probably released from vesicles into the cytoplasm via secondary lysosomes.

Studies on cholera-toxin-induced desensitization of adenylate cyclase in the mouse intestinal mucosa

Repeated peroral pretreatment ('immunization') with cholera toxin (CT) in mice induces protection against CT as well as against prostaglandin E1 (PGE1), as evaluated by fluid accumulation in intestinal loops. The fluid response to CT is depressed for more than 1 month, while the response to PGE1 is inhibited for 4-7 days after the pretreatment. Immunofluorescence microscopy revealed that neither the binding nor the penetration of CT into the intestinal epithelial cells is affected by the toxin pretreatment. Furthermore, the CT-induced release of mucus in goblet cells is not influenced by the toxin pretreatment. In contrast, the enzyme adenylate cyclase (AC), which mediates the actions of CT and PGE1, shows a long-lasting desensitization to CT, as estimated in mucosal membrane preparations. Chlorpromazine and cycloheximide revert the desensitization to CT as well as to PGE1. The present data suggest that intestinal resistance to CT in the mouse is due to desensitization of the reaction between CT and AC and requires stimulation of AC, as well as an active protein synthesis.

Ultrastructural localization of fibronectin in duct cells of human minor salivary glands and its immunochemical detection in minor salivary gland secretion

Fibronectin (Fn) was localized in duct cells by means of a light and electron microscopic immunohistochemical technique. The subcellular localization demonstrated that Fn is synthesized in these cells and thus not exclusively produced by cells with a mesodermal background. Fn concentration, as measured by radioimmunoassay, was higher in saliva from the minor salivary glands than in unstimulated whole saliva, whereas Fn was undetectable in stimulated parotid saliva. Fn is thus a conspicuous component in unstimulated resting saliva. Fn may be an important factor, negative or positive, for the integrity of the oral hard and soft tissues because it has the capability to bind and agglutinate microorganisms.

Ultrastructural aspects of the interface between bone and cement in man. Report of three cases

An extremely strong mechanical bond between cement and bone was observed in three patients with cemented hip protheses who underwent revision operations. The nature of the bone--cement attachment was studied by electron microscopy. The tissue at the interface was found to be made up of viable bone alternating with areas of soft tissue containing macrophages. The important qualitative differences between this reaction and the reaction seen around inert materials such as titanium are discussed.

Effect of radiologic contrast media and local anaesthetics on the blood-brain barrier and on the leptomeninges

The leptomeninges of cats were exposed to lidocaine, metrizamide and methiodal sodium and compared with control brains exposed to Ringer's solution. As a sign of blood-brain barrier damage, an increased extravasation of albumin into the cerebral cortex was recorded after exposure to methiodal sodium; lidocaine or metrizamide did not produce such damage. Scanning electron microscopy revealed minor cellular reactions in the mesothelial cells of the leptomeninges after application of metrizamide, lidocaine and Ringer's solution. Methiodal sodium produced an extensive cellular damage of the leptomeningeal cells. The importance of testing the leptomeningeal reactions and the reactions of the blood-brain barrier to all liquid media used on the brain surface is emphasized.