Biomedical subjects
Publications and source records attributed to Y Takei.
A 30-year-old women suffered from right superior eyelid infestation of Ixodes ovatus Neumann, which was mechanically removed with forceps after application of benzine. No mouth parts were retained in the eyelid. Removed mouth parts were examined by a scanning electron microscope. There were no complications except focal trichotylosis in the involved area. The mode of attachment of the tick to the host and the method of removal were discussed.
Ultrastructural studies of yolk sac tumors (YST) have generally demonstrated the resemblance of this neoplasm to the primitive human yolk sac. However, these studies have failed to explain the common occurrence of mixed germ cell tumors with yolk sac elements. This report describes the ultrastructural features of a suprasellar YST. This tumor resembled those previously described. Also demonstrated, however, was the presence of primitive germ cells admixed within the neoplasm. A new schema is proposed based on these observations for the interrelationship of germ cell tumors, which may explain the common occurrence of mixed germ cell tumors.
Medulloblastoma is a relatively common and well-established entity, consisting of primitive, multipotential cells that may exhibit some evidence of neuroblastic or glial differentiation. However, cerebellar "neuroblastoma" with ultrastructural evidence of significant neuroblastic differentiation are extremely rare. We have studied three tumors with light microscopic evidence of neuroblastic differentiation. All of these tumors have regions resembling medulloblastoma; this finding suggests that cerebellar "neuroblastoma" represents one form of medulloblastoma. These cases provide further evidence for the potential medulloblastoma cells to differentiate along neuronal lines.
Cerebral neuroblastoma is a rare neoplasm that has not previously been associated with a phakomatosis. We report a case of an intraventricular neuroblastoma in a patient with Von Hippel-Lindau's disease. The neoplasm consisted of process-forming cells containing clear vesicles, dense-cored granules and microtubules. An unusual finding was the presence of intertwining cytoplasmic processes, apparently representing aberrant process formation. We suggest that this case represents a cerebral neuroblastoma occurring as an unusual manifestation of a phakomatosis.
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A rapid pseudoreplica method of electron microscopy (EM) was used to detect viruses in brain tissues obtained from 57 patients suspected of having herpes simplex encephalitis (HSE). Herpesvirus particles were demonstrated in 18 of the 20 (90%) specimens from which herpes simplex virus was isolated in tissue culture. The procedure takes less than 2 hours, as compared to the time (greater than or equal to 2 days) usually required for virus isolation or standard thin-section electron microscopy. Although the immunofluorescence test has comparable rapidity, it was found to be less sensitive and to yield occasionally false-positive reactions. Our findings indicate that, until a brain biopsy can be replaced by less invasive procedures, examination of brain tissue by the pseudoreplica method offers a rapid diagnosis of a herpesvirus encephalitis. Furthermore, the demonstration of viruses in brain, lung and liver specimens obtained by biopsy or at autopsy suggests that this electron-microscopic method would be advantageous for detecting viruses in tissue samples, particularly in the case of viruses which may not be readily demonstrable by conventional methods.
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Lonomycin A at various concentrations was tested for its inhibitory effect on Toxoplasma multiplication in host cells cultured in vitro. Results indicate that lonomycin A at a concentration of 0.01 micrograms per ml in TC-199 medium demonstrated a high degree of antitoxoplasma activity with complete inhibition of Toxoplasma multiplication in the host cells. Lymphokines, a supernatant produced from spleen cells of mice infected chronically with Toxoplasma gondii, inhibited Toxoplasma multiplication in mice macrophage and kidney cell monolayers. However, lonomycin A inhibited completely Toxoplasma multiplication in non-specific cells, i.e. not only in mice macrophages and kidney cells but also in cells of human and other animal species.
In beagles infected with Toxoplasma tachyzoites, IgM and IgG humoral antibodies appeared on the early period of infection as the expression of the humoral antibody response. IgM antibody was no longer observed after 16 days, however, IgG antibody persisted maintaining high titers up to the last day of the experiment. When challenged on the 13th day postinfection, IgG antibody levels were boosted, however, IgM levels did not show any change at all. Lymphokines obtained from spleen cells collected 10, 30, 100 and 300 days postinfection showed a gradual increase in the ability to inhibit Toxoplasma multiplication in normal canine monocytes accordingly compared to the control which showed no inhibition at all. Toxoplasma lysate antigen was injected intravenously to hyperimmuned dog 2 wk after rechallenge. Plasma collected 24 hr after injection inhibited markedly Toxoplasma multiplication. No change in the microbicidal activity was found when plasma was absorbed with anti-canine IgG compared to the unabsorbed one. The results therefore indicated that the substance inhibiting Toxoplasma multiplication in canine monocytes existing in plasma is not derived from antibodies specific for Toxoplasma but as a Toxoplasma growth inhibitory factor (Toxo-GIF) or a similar substance. The plasma obtained also showed antiviral activity of interferon type II and was found to increase in the circulation 6 hr after Toxoplasma lysate antigen injection.
Mice sensitized with frozen-thawed Toxoplasma antigen emulsified in Freund's Incomplete Adjuvant (FIA) showed high resistance against Plasmodium berghei infection, but not in mice sensitized with paraformaldehyde-fixed. Toxoplasma or saline plus FIA. However, mice which survived from malaria infection did not show any protective reaction against the RH strain inoculation. Furthermore, an immune interferon activity was detected in the supernatant of the spleen cells collected from the mice sensitized with frozen-thawed Toxoplasma and cultured with the specific antigen, however, no Toxoplasma growth inhibitory factor (Toxo-GIF) was found in the same supernatant of lymphokines. From these results, it is suggested strongly that frozen-thawed Toxoplasma antigen could confer nonspecific resistance in mice against Plasmodium infection.
Assessment in vitro were carried out to study Toxo-GIF and IFN in lymphokines, LKs, produced by immune spleen cells with Toxoplasma lysate antigen (TLA). LKs were obtained from the cells after incubation for 24 to 48 h with TLA. They inhibited almost completely the intracellular multiplication of Toxoplasma (Tp) within homologous cells. Peak IFN activities were observed in the same LKs. The IFN was inactivated at pH 2, but did not lose its activity at 56 degrees C, suggesting that it might be type II or gamma IFN. Further evidence was presented of the coordinate production and properties of Toxo-GIF and IFN in the circulating blood of Tp-immune mice injected intraperitoneally with TLA or Poly I: C. The IFN was designated type II or gamma IFN. Its maximum activity appeared in Tp-immune mice 6 h after TLA or Poly I: C injection, while a maximum Toxo-GIF activity was observed in these mice 24 to 48 h after injection. Type I IFN activity was detected in the serum of normal mice injected with TLA or Poly I: C. Type I IFN differed markedly from type II IFN, because it was stable at pH 2 and unstable at 56 degrees C. Evidence was presented which emphasized the difference in activity in relation to the time of appearance between Toxo-GIF and IFN.
A case of typical erythema rheumaticum is presented with emphasis on clinical, histological, immunopathological and immunological findings. Pathogenesis and therapy are shortly discussed.
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Pituitary tumors with features of both Rathke's cleft cysts and adenohypophysial adenomas are extremely rare and have been termed "transitional cel tumors." The ultrastructural features of one of these tumors has been reported, demonstrating cells with features transitional between those of adenohypophysial cells and Rathke's cleft cells, along with other cells with the distinctive features of either cell type. We report a case of a prolactin-secreting "transitional cell tumor" with similar light-microscopic and ultrastructural features. Additionally, the transitional cells in our case exhibited abundant intracellular mucin production. This represents a variant of "transitional cell tumor" of the pituitary gland.
The vascular and perivascular regions of the human neurohypophysis were studied electron microscopically. The abluminal basement membrane, perivascular space, luminal basement membrane and endothelium are interposed between the neural parenchyma and the blood stream. The capillaries are fenestrated, with pores measuring 30 to 50 nm in diameter. The perivascular and intercellular spaces form prominent networks that penetrate between rows of neurohypophysial parenchymal cells. The perivascular space contains pericytes, histiocytes, fibroblasts and mast cells, with ultrastructural features typical of each cell type. No transitional forms between histiocytes and pericytes were observed. A schema for the extracellular flow of neurohypophysial hormones through the sinusoidal and perivascular spaces is proposed, suggesting an important role for the pituicytes and their intercellular junctions in the control of hormone release.
Neurosecretory axons and their dilatations in the pars nervosa of the human neurohypophysis were studied electron microscopically. The axons are of two different types based on their content of neurosecretory granules (NSGs): (i) NSGs of Type A are 100-300 nm, and (ii) NSGs of type B are 50-100 nm in diameter. While fibers (or axons) of type B were scarce, showing simple swellings and terminal formations, fibers of type A were ubiquitous in the human pars nervosa, exhibiting numerous dilatations with a diversity of internal structure, apparently representing the ultrastructural manifestation of intraaxonal turnover of neurohypophysial hormones. Based on the predominating aspect of their internal structure, dilatations of type A-fibers were classified into six different types, with various transitional forms: Type I is characterized by abundant NSGs; type II by prominent mitochondria; type III by abundant lysosomal bodies; type IV by an electron-lucent matrix with few organelles; type V by prominent tubuloreticular profiles; and type VI by numerous microvesicles. The functional significance of each type is discussed and a scheme of possible interrelationships between these dilatations is proposed.