Megakaryocyte and platelet morphology.
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Animals↗
Biomedical subjects
T Hovig
Publications and source records attributed to T Hovig.
Neuroendocrine carcinoma of the lip (Merkel cell tumour) examined by electron microscopy and immunohistochemistry.
A definite diagnosis of neuroendocrine carcinoma of the skin is seldom made on initial histological examination; the tumour is usually reported as a poorly differentiated or anaplastic carcinoma. By applying electron microscopy and immunohistochemistry, a correct diagnosis can be made. The ultrastructural examination shows dense-core membrane-bound granules, intermediate perinuclear filaments and desmosome-like junctions. Immunohistochemistry reveals positive staining for neuron-specific enolase and keratin, the latter in a characteristic paranuclear distribution. Confronted with an unusual clinical picture or indefinite histological diagnosis, tissue specimens should be secured for the above mentioned ancillary procedures.
Aged↗
Rhabdomyoma of the tongue. Report of a case with light microscopic, ultrastructural and immunohistochemical observations.
Adult rhabdomyoma is a benign neoplasm of skeletal muscle origin, which mainly occurs in the head and neck region. Because of its rarity the diagnosis may be missed, especially if cross-striations cannot be demonstrated by light microscopy. By applying supplementary diagnostic evaluation with immunohistochemistry and electron microscopy, the diagnosis is established. Positive staining with desmin unequivocally demonstrates that the tumour cells are derived from muscle tissue. The presence of myofibrils, Z-bands and numerous mitochondria by ultrastructural examination are characteristic features of this tumour.
Humans↗
Peritoneal, benign, cystic mesothelioma with free-floating cysts, re-examined by new methods. A case report.
A histologically-confirmed, multicystic, benign mesothelioma, with free-floating, thin-walled cysts, in the abdominal cavity of a 27-year-old woman was reported in 1954. After removal of all visible cysts by laparotomy, the patient was healthy and well for 29 years, when she was surgically treated for cholecystitis and gall bladder stones in 1982. The whole peritoneum was found covered with small cysts lined by mesothelial cells. The patient is (April 1987) well, with no complaints. Sections from the old paraffin blocks were studied by means of scanning, transmission electron microscopy and immunohistochemistry. These methods confirmed the histological diagnosis. The authors discuss whether such a lesion really is a benign tumor or should rather be otherwise classified.
Abdominal Neoplasms↗
Ultrastructural identification of platelet surface glycoproteins and particle endocytosis with gold-labeled reagents.
Blood platet surface labeling was obtained by the use of the lectins concavalin A and wheat germ agglutinin. Colloidal gold particles coated with horseradish peroxidase and ovomucoid respectively were used as markers. Also erythrocytes and leukocytes were labeled. Using monoclonal antibodies against the platelet surface glycoproteins Ib and IIb-IIIa specific labeling of the platelets was obtained, whereas the red cells and the leukocytes were entirely free of labeling. With glutaraldehyde fixed platelets no gold particle uptake was observed. With unfixed normal platelets, however, surface membrane-associated particles were sometimes observed within the surface connecting canalicular system, and occasionally in small vesicles. In unfixed platelets from a patient with thrombocytopathia, possible platelet endocytosis of the membrane bound particles was observed with particles assumed to be transported via vesicles to granules probably representing lysosomal structures.
Antibodies, Monoclonal↗
Abnormal phosphoinositide metabolism and protein phosphorylation in platelets from a patient with the grey platelet syndrome.
Washed platelets isolated from one patient suffering from the inherited grey platelet syndrome were studied during thrombin-induced activation. The agonist-induced changes in (i) morphology, (ii) typical functional cell responses, (iii) membrane phospholipid metabolism and protein phosphorylation were studied and compared with the changes obtained with normal platelets. The morphology of the platelets as visualized by electron microscopy confirmed the almost total absence of intracellular alpha-granules and marked vacuolization. During thrombin stimulation the morphological changes were clearly delayed as compared to normal platelets, the granule centralization and aggregation occurred only 15 s after thrombin addition instead of 5 s in normal platelets. After 15 s, however, even though no alpha-granules were observed, a ring-like structure occurred centrally, indicating that they are not a prerequisite for this reaction. The whole release reaction, i.e. liberation of [14C]serotonin from dense granules and beta-N-acetylglucosaminidase activity from lysosomes, and the thromboxane synthesis were delayed and remained lower than in normal platelets. No thrombin-induced phosphatidyl 4,5-bisphosphate breakdown was measurable on 32P-prelabelled platelets although [32P]phosphatidate formation occurred normally. Phosphorylation time courses of myosin light chain (P20) and of protein P43 (mol wt 43,000) markedly differed from those of controls, being less than half of the normal during the first 15 s and remaining subnormal even after complete aggregation. These results suggest that in platelets devoid of alpha-granules a deficient transmembrane signalling system is likely responsible for the impaired physiological responses.
Blood Platelet Disorders↗
The influence of fixation on the morphology of mouse epidermis. A light and electron microscopical study with special reference to "dark cells" and epidermal carcinogenesis.
Different opinions exist on the normal ultrastructure of the epidermis including the significance of so-called basal dark cells. Thus, the dark cells are still assumed to be key elements in experimental skin carcinogenesis. We therefore explored the effects of tissue fixation on the ultrastructure of the epidermis. Untreated normal hairless mouse skin was processed for transmission electron microscopy with two different sets of fixatives, applied either by perfusion-immersion or immersion fixation only. The morphology of both the basal and the lower suprabasal layers of the epidermis, including the extracellular space, the shape and volume of the cells, their electron density, and the organisation of some of the organelles, were profoundly affected by the choice of fixatives. The non-keratinocytes showed comparable changes, including the appearance of a dark phenotype. The incidence of small electron-dense keratinocytes (dark cells) and the nature of their ultrastructure changed markedly with the fixation procedure. We were not able to identify undifferentiated dark cells. The pattern of changes and the quality of the morphological picture were almost unaffected by the mode of fixation. The upper suprabasal and the cornified layers appeared to be more or less unaltered by the change in fixatives and the method of application. The vehicle osmolality of the primary fixative was found to be mainly responsible for the ultrastructural appearances. A low vehicle osmolality may be responsible for the occurrence of the dark cell phenomenon, by inducing swelling artefacts of many cells with compression of some neighbouring cells.
Animals↗
The influence of different fixatives and a tumor promoter, 12-0-tetradecanoyl-phorbol-13-acetate (TPA), on the induction of so-called dark cells in mouse epidermis. A light microscopical study.
Epidermal "dark cells" (DC) are believed to play a specific role in the so-called promotion phase of experimental skin carcinogenesis. They are recognized by their morphological features both at the light and the electron microscopical level. The possible effects of fixation on the morphology of epidermal cells and hence on the number of DC have not yet been thoroughly studied. In the present light microscopical study we used a semiquantitative method together with simple cell counting to evaluate the influence of fixation on the specific cellular morphology which is traditionally used to determine the number of DC. The use of cacodylate vehicled prefixatives, either formaldehyde or glutaraldehyde, led to a higher incidence of DC, and furthermore both to an increased width of the intercellular spaces (ICS) and a more heavy staining of the keratinocytes than when s-collidine vehicled glutaraldehyde was used. Differences in yield of DC solely due to the prefixative itself (formaldehyde or glutaraldehyde) were not detected. Exposure to TPA or the use of a hyperosmolal prefixative vehicle both yielded higher DC numbers than did controls or conventional prefixative vehicles, respectively. After prefixation with hyperosmolal vehicles, however, TPA treatment did not induce higher DC yield than in a control series. Phenomena usually accompanying exposure to TPA, such as intercellular oedema (widening of the ICS) and cytoplasmic vacuolization, varied in parallel to the number of DC. Hence, there is reason to believe that the induction of epidermal DC is mainly associated with volume reduction of keratinocytes. Such shrinkage may be due to the cytotoxic properties of TPA and degenerative phenomena appearing during tissue processing.
Acetone↗
Formation of prostanoids in human umbilical vessels perfused in vitro.
Four major prostanoids (6-keto-PGF1 alpha, PGE2, PGF2 alpha and TXB2) were measured by specific radioimmunoassays in the outputs from human umbilical vessels perfused in vitro. As evaluated by scanning electron microscopy (SEM) only few blood platelets were attached to the vessel wall. After an initial flush with decreasing concentrations of all four prostanoids, a stable stage was reached, lasting for 4-5 hours. During this stage the production could be inhibited by indomethacin and only slightly stimulated with arachidonic acid. The TXA2 synthetase inhibitor UK 38485 depressed the TXB2 production, while only slightly affecting the other three prostanoids at very high concentrations. The arteries produced relatively more 6-keto-PGF1 alpha than did the vein.
6-Ketoprostaglandin F1 alpha↗
Rheumatoid synovial dendritic cells as stimulators in allogeneic and autologous mixed leukocyte reactions--comparison with autologous monocytes as stimulator cells.
Dendritic cells were isolated from peripheral blood, synovial fluid, and synovial tissue of patients with rheumatoid arthritis and from peripheral blood of healthy blood donors on the basis of semiadherence to plastic surfaces. The cells were compared with autologous peripheral blood monocytes with respect to their stimulating capacities in allogeneic and autologous mixed leukocyte reactions (MLR). Dendritic cells from the various compartments stimulated allogeneic T cells 6-14 times more than monocytes did. Dendritic cells also stimulated autologous T cells 10-24 times more than monocytes did. Evidence in favour of the dendritic cell as the major stimulating cell type in MLR was also found in mixed experiments in which various ratios of dendritic cells and monocytes were used as stimulator cells. Furthermore, the activating structures on the dendritic cells seem to be major histocompatibility complex class II antigens, since anti-HLA-DR antibodies inhibited the responses. The results, especially from the autologous MLR, indicate that dendritic cells are important accessory cells for the various immune responses in rheumatoid inflammation.
Antibodies, Monoclonal↗
Ferrochelatase deficiency of the bone marrow in a syndrome of congenital microcytic anaemia with iron overload of the liver and hyperferraemia.
Ferrochelatase deficiency of the bone marrow was found in 2 sisters with a syndrome of congenital hypochromic anaemia, hyperferraemia and heavy iron deposits in the liver.
Anemia↗
Collagenous colitis. A clinical, histological, and ultrastructural study.
Eleven patients with so-called collagenous colitis are described and the literature reviewed. The disease presents with persisting watery diarrhoea in middle-aged subjects, predominantly women. The fairly uniform clinical features of abdominal discomfort are suggestive of the irritable bowel syndrome. The morphological changes in colorectal biopsy specimens are diagnostic, showing an excessive intercryptal subepithelial collagen deposition throughout the large bowel. Associated hyperplasia, degeneration, and desquamation are seen in the intercryptal epithelial cells and a mild inflammatory response in the lamina propria. A comparable collagenization has not been demonstrated in other disorders, but otherwise the changes demonstrated histologically and ultrastructurally are of a quantitative nature. Collagenous colitis is unrelated to other diseases and the cause unknown. It has either a benign, continuous course or exacerbations and remissions. Loperamide relieved diarrhoea in five of six patients. The collagen deposition seems to be slowly progressive, but clinical and histopathological resolution may occasionally be seen.
Adult↗
Ferrochelatase deficiency in the bone marrow in a syndrome of congenital hypochromic microcytic anemia, hyperferremia, and iron overload of the liver.
Two sisters had congenital hypochromic microcytic anemia with hyperferremia, heavy iron deposits in the liver, and reduced bone marrow iron. Liver ferrochelatase activity was within normal limits, but in the bone marrow ferrochelatase activity was only 20% of that in healthy controls. There were no findings suggestive of lead intoxication, sideroblastic anemia, or erythropoietic protoporphyria.
Adult↗
Bacterial overgrowth.
Different aspects of bacterial overgrowth in the small intestine are reviewed. The pathophysiological mechanisms involving both bacterial metabolism of dietary components and secretions and effects on the mucosal cells are discussed in more detail. The current therapy, surgical, medical and supportive, is outlined.
Anti-Bacterial Agents↗
Recurrent diffuse pulmonary hemorrhage with minor kidney lesions.
This case report concerns a 14-year-old boy with a 3 month history of dyspnea and iron deficiency anemia. On admission he had hemoptysis and bilateral pulmonary shadows. Transbronchial lung biopsies showed linear deposits of IgG and C3 in the alveolar basement membrane, but no anti-GBM antibodies were observed in serum or kidney biopsy. The ratio of the T cell subpopulations T4/T8 in peripheral blood was in the early stage, 5 and, thus, elevated. The patient was given prednisolone 1 to 0.25 mg/kg and cyclophosphamide 2 mg/kg with temporary cessation of pulmonary bleeding. Hemoptysis recurred and plasma exchange was performed with success.
Adolescent↗
Imerslund-Gräsbeck anemia. A long-term follow-up study.
A follow-up study has been performed on 14 patients, now aged 6-46 years, with Imerslund-Gräsbeck anemia (congenital, hereditary selective malasorption of vitamin B12). On intramuscular vitamin B12 therapy, the patients are clinically and hematologically normal. Those who had constant proteinuria in childhood continue to excrete protein in the urine. Our patients excrete an average of 750 mg of protein per 24 hours (range 13-1460 mg). The proteinuria is predominantly of glomerular origin, but some is also of tubular origin. Renal biopsies of the two oldest patients were normal on light microscopy. Electron microscopy revealed moderate signs of chronic glomerulopathy of mesangioproliferative type in both patients. The renal lesions do not seem to be progressive.
Adolescent↗