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  • Author or Editor: Shinjiro Yamamoto x
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Tetsumori Yamashima, Toshihiko Kubota and Shinjiro Yamamoto

✓ A previously unrecognized role of eosinophils in chronic subdural hematomas is described. Outer membranes of hematomas with marked infiltration by eosinophils were studied ultrastructurally with particular attention to the degranulation of these cells. In all of the five cases studied, degranulation was observed. Disintegration of the cells contributed to the release of granules. The free granules, the matrix of which has been demonstrated to contain plasminogen, were often circulating in the vascular lumen and trapped among the aggregated platelets. They were also found within the fragile vascular wall surrounded by fibrinoid material and in the edematous perivascular interstitium. Some of the perivascular eosinophils showed frank solubilization of granule matrix contents in spite of unaltered crystalloids. These findings suggest a role of eosinophils in the development of local hyperfibrinolysis within the outer membranes, which might contribute to the fluidity of chronic subdural hematomas and the resultant leakage of blood from the vessels in the capsules.

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Toshihiko Kubota, Kazufumi Sato, Shinjiro Yamamoto and Asao Hirano

✓ The fine structure of psammoma bodies was examined in four cases of fibroblastic meningioma. In general, large numbers of various-sized calcified bodies (psammoma bodies) were scattered among the interstitial fibers. In these bodies, the smallest calcific site was found in the extracellular membrane-bound matrix vesicles, which measured approximately 0.1 to 0.2 µ in diameter. In addition, extracellular “matrix giant bodies,” with or without hydroxyapatite aggregates and measuring up to 3 µ in diameter, were frequently encountered. These bodies were apparently invested with single, double, or multiple concentric walls averaging nearly 0.1 µ thick. They presumably originated from the neoplastic cells as a consequence of cytoplasmic residuals associated with cellular degeneration or necrotic cell processes. Hydroxyapatite crystals precipitated repeatedly within the bodies. The precipitate may gradually aggregate within the bodies, and gather in clusters, resulting in a large psammoma body. Finally, collagen fibers around the calcified giant bodies accrued deposits of apatite crystals to make a huge psammoma body. These findings suggest that both matrix giant bodies and matrix vesicles may serve as initial nidus of calcification of psammoma bodies in fibroblastic meningioma. Consequently, this mineralization process may represent a certain dystrophic calcification of meningocytic cells.

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Kiyonobu Ikeda, Toshihiko Kubota, Kengo Kashihara and Shinjiro Yamamoto

✓ Intraoperative monitoring of anorectal pressure was used in a case of sacral lipomeningocele accompanied by congenital dermal sinus to protect the physiological function of the anorectal sphincters. This monitoring system consists of a manometric anorectal balloon and neural electrical stimulation. The system was able to differentiate functioning neural structures from surrounding tissues during the operation.

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Shinya Kida, Tetsumori Yamashima, Toshihiko Kubota, Haruhide Ito and Shinjiro Yamamoto

✓ The structure of human arachnoid villi was investigated by light and electron microscopy with the aid of immunohistochemical techniques. The human arachnoid villi examined were basically composed of four portions: a fibrous capsule, an arachnoid cell layer, a cap cell cluster, and a central core. The arachnoid cell layer encompassing the central core was mostly covered by the thin fibrous capsule with an endothelial investment. However, the fibrous capsule was often absent at the apical portion of the villus and a factor VIII-related antigen stain failed to confirm the investment of endothelial cells. Instead, the arachnoid cell layer abutted directly upon the lumen of a lateral lacuna or the sinus. The arachnoid cell layer was thickened in places, forming cap cell clusters; it usually consisted of outer and inner zones. On vimentin staining, the former was slightly positive while the latter was strongly positive. The central core contained a network of arachnoid cells intermingled with connective tissue fibers and was in continuity with the cranial subarachnoid space. Electron microscopy showed that the arachnoid cells contained a larger number of intermediate filaments in the inner zone than the outer zone. Ultrastructural immunohistochemical localization showed that vimentin was localized at the intermediate filaments and desmosomal plaques of the arachnoid cells. The arachnoid cells showed a marked variety in both the cell forms and the number of intermediate filaments or desmosomes, depending on their location.

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Toshihiko Kubota, Kazuhumi Sato, Hirokazu Kawano, Shinjiro Yamamoto, Asao Hirano and Yoshio Hashizume

✓ A case of ossification of the cervical posterior longitudinal ligament was investigated with the electron microscope. The posterior longitudinal ligament was composed of bundles of collagen fibers intermingled with occasional fibroblasts and rare blood vessels. Some ligaments contained matrix vesicles in the vicinity of degenerated cells. Hydroxyapatite crystals were frequently precipitated within the matrix vesicles. These findings are similar to the fine structure of the early stage of calcification in normal and pathological calcifying tissues described previously. In this study, the calcification process of the posterior longitudinal ligament suggests that matrix vesicles originate from degenerated cells, and acquire hydroxyapatite crystal deposits. Some eventually coalesce to form a large calcifying mass. Substantial amounts of collagen fibers comprising the ligament may serve an important role in orienting apatite crystal precipitation.

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Takeshi Hasegawa, Haruhide Ito, Katsuo Shoin, Yuzaburo Kogure, Toshihiko Kubota and Shinjiro Yamamoto

✓ A case of Nelson's syndrome with an adrenocorticotropic hormone-secreting pituitary chromophobe microadenoma is presented to demonstrate the potential capability of rapid sequential (dynamic) computerized tomography (CT) scanning for the diagnosis of a pituitary microadenoma that was isodense with the adjacent pituitary gland on conventional enhanced CT scanning. The dynamic CT scans showed transient high density in this microadenoma contrasting with the pituitary gland in the early-enhancement phase, and thereafter the contrast density was indistinguishable from that of the pituitary gland in the delayed-enhancement phase. For the detection of pituitary microadenoma, dynamic CT combined with subsequent delayed CT scanning can provide diagnostic and localizing information.