Tatsuo Oguro

Characteristics of histopathological and ultrastructural features of placental villi in pregnant Nepalese women.

The placenta is an important functional unit for gas transfer between mother and fetus. The placental membrane, consisting of trophoblast layer interposed between maternal and fetal blood, plays an active role for intensity of respiration, but no morphological evidence has been documented. Until now, it has been reported that fetal growth retardation and increased fetal mortality rate usually could be seen at high altitude. In an attempt to find the cause of high perinatal mortality rate in Nepal, this study was undertaken to examine pathologically about 1000 Himalayan placentas obtained in Nepal and Tibet since 1977, and the results were compared with those of 5500 Japanese placentas at Saitama Medical School since 1990. In this study, characteristics of ultrastructural features of the Nepalese placental villi investigated in recent years are reported. (1) The gross characteristics of placental pathology in the Himalayan group were represented by marked subchorionic fibrin deposits and increased chorionic cysts in contrast to low incidence of intervillous thrombosis compared with those of the Japanese group. (2) As characteristics of histological findings of the placental villi between Himalayan and Japanese groups, the incidence of chorangiosis and chorangioma in the Himalayan group was significantly higher than that in the Japanese group. (3) Accompanying an increase of vasculosyncytial membrane (VSM) in the villi, thickness and separation of basement membrane of the syncytium in addition to increased apoptosis of syncytial cell nuclei were recognized. (4) As characteristic ultrastructural features of chorionic villi of Nepalese placentas, an increase of mitochondria and cystic formation of rough endoplasmic reticulum (rER), in addition to appearance of lamellar bodies similar to alveolar epithelial type II cell in organellae of the syncytium, were observed. These ultrastructural changes of the placental villous capillaries may be ascribed to hypevascularization caused by the chronic hypoxic state. It is, therefore, presumed that trophoblast cells may play an important role for gas transfer mecha-nism under such a hypoxic state at high altitude.

Mitochondrial encephalomyopathy with lactic acidosis and stroke like episodes (MELAS) with prominent degeneration of the intestinal wall and cactus-like cerebellar pathology

Abstract A 67-year-old woman had frequent subacute ileus, hearing difficulty, muscle atrophy and stroke-like episodes. Computed tomography revealed multiple low-density areas, which did not correlate with the vascular supply, in the cerebral cortex. She had metabolic disturbance comprising lactic acidosis and elevated pyruvate level. Her skeletal muscle biopsy specimen showed ragged-red fibers, and mitochondrial DNA analysis revealed a point mutation at position 3243, findings consistent with MELAS. Examination of her small intestine revealed a necrotic zone and numerous abnormal large mitochondria in the smooth muscle cells, vascular media and endothelium, and intestinal ganglion cells. The cerebral cortex showed multiple microcystic necrotic foci in cerebral cortex. Cactus-like pathology resembling the changes associated with Menkes’ kinky hair disease and torpedoes were observed in the cerebellar Purkinje cells. The intestinal dysmotility due to MELAS and cerebellar changes were presumed to be associated with a disturbance of copper metabolism.

Silver staining of nucleolar organizer regions in prostatic lesions

Variations in the number of silver‐stained nucleolar organizer region‐associated proteins (AgNORs) were studied in paraffin sections of 42 benign prostatic lesions, comprising four cases of granulomatous prostatitis, five of squamous or transitional metaplasia, eight of atypical and 25 of regular hyperplasia, and 37 of prostatic adenocarcinoma, with their metastases. There was a significant difference between the mean AgNOR counts of the benign and malignant prostatic lesions (1.58±0.26 v. 4.34±1.53; P<0.01). The mean AgNOR counts significantly increased with increasing Gleasons grade (P<0.01) and clinical stage (P<0.05) of the tumours. AgNOR counting may contribute to the conventional diagnostic and prognostic indices of cancer of the prostate.

Interaction between β-amyloid protein and heparan sulfate proteoglycans from the cerebral capillary basement membrane in Alzheimer’s disease

Proteoglycans are important in the pathogenesis of senile dementia of Alzheimer type (SDAT) by participating in amyloidogenesis. Knowledge about specific proteoglycan subtypes in SDAT may be of therapeutic advantage. In this study, we examined proteoglycan constituents of SDAT brains with reference to hyaluronic acid, heparan sulfate (HS), dermatan sulfate and chondroitin sulfate subtypes. Total proteoglycans showed a 1.6-fold increase in the hippocampus and 4.3-fold increase in the gyrus frontalis superior compared to non-demented elderly subjects. The HS subtype showed a 9.3-fold increase in hippocampus and a 6.6-fold increase in gyrus frontalis superior. Immunohistochemical studies of senile plaques revealed the expression of heparan sulfate proteoglycan (HSPG) in a portion of the core of typical plaques. beta-amyloid expression was positive in senile plaques and the degenerated neuronal processes and capillary basement membrane, but was negative in endothelial cells. Microglial cells adjacent to senile plaques were positive for HLA-DR expression, and astroglial cells positive for glial fibrillary acidic protein were scattered around the microglial cells. Immunoelectron microscopic examination showed an electron-dense reaction for HSPG in the thickened basement membrane adjacent to the endothelial cells of capillary vessels, but not inside the endothelial cells. These findings suggest that a markedly increased HSPG in SDAT brains is most likely caused by HSPG from the blood capillary basement membrane and that the degenerated processes around senile plaques may arise from microglial or astroglial cells.

P57kip2 immunohistochemical expression and ultrastructural findings of gestational trophoblastic disease and related disorders

Gestational trophoblastic disease (GTD) is a unique spectrum of diseases ranging from complete hydatidiform mole (CHM), partial hydatidiform mole (PHM), and invasive mole (IM) to choriocarcinoma (CC). Placental site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT) have been classified as related disorders. Mesenchymal dysplasia (MD) may be misdiagnosed as PHM; however, it is said to have a quite different histogenesis from PHM. P57kip2 is the protein product of a paternally imprinted or maternal gene that inhibits cyclin-dependent kinases (CDK), thus serving to inhibit cell proliferation and to suppress tumor growth. Its lack of expression in trophoblastic disease plays a role in its abnormal proliferation and differentiation. In this study, P57kip2 immunostaining was absent in the trophoblastic layers of CHM and was positive in the trophoblast layer of nonmolar villi and MD. Ultrastructure of complete molar cystic villi showed tree-like branching of microvillous processes and intracytoplasmic lacunae without capillaries in the stroma, whereas MD contained many newly formed blood vessels and collagen. Also, large lacunae with microvilli and polymorphic nuclei of syncytiotrophoblast cells with well-developed organelles were observed in IM. Lung ETT following CHM and normal deliveries showed two types of large mononuclear cells and binuclear cells with abundant organelles and bundles of intermediate-type filaments in the stroma.

Establishment and Characterization of a Human Rectal Neuroendocrine Carcinoma Xenograft into Nude Mice

Background: Carcinoid tumor has been recognized as having a much wider spectrum than was previously thought. Now the term ‘neuroendocrine carcinoma’ (NEC) has been suggested to describe malignant epithelial tumors of neuroendocrine differentiation. Its biological behavior has not been well characterized because of the lack of in vivo models. Materials and Methods: A metastatic inguinal lymph node from rectal NEC was used for heterotransplantation into nude mice. Histochemical and immunohistochemical stainings were performed in addition to ultrastructural investigations. Hormonal peptides were measured in both xenograft tumor tissue and serum. Results: We succeeded in heterotransplantation of human rectal NEC into nude mice. To date tumorigenicity has been retained for approximately 38 months. The xenograft tumor was a histopathologically identical tumor. The immunohistochemical expression of the various hormonal peptides in the xenograft was essentially the same as that of the primary rectal tumor. Tissue and serum hormonal peptides in the xenografted tumor were measured. Serum glucagon and serotonin were significantly higher than in control mice. Conclusions: The expression of various hormonal peptides in NEC may vary depending on the surrounding environment. The establishment of NEC in xenografts provides a model for further study of the biological behavior of NEC, as well as the in vivo effects of chemotherapeutic agents on tumor growth and the release of hormonal peptides.

Combined immunohistochemical study of tissue polypeptide antigen and cancer antigen 125 in human ovarian tumours

An indirect immunoperoxidase method was used to study the expression of tissue polypeptide antigen (TPA) and cancer antigen 125 (CA 125) in 47 benign and malignant ovarian tumours. Tissue polypeptide antigen and CA 125 antigen were expressed respectively in 22 (73%) and 16 (53%) of the 30 adenocarcinomas and in five (29%) and four (23%) of the 17 benign tumours. Co‐expression of TPA and CA 125 antigen occurred in 12 (40%) malignant and four (23%) benign tumours. Ultrastructurally, TPA and CA 125 antigens were located at the cell surface and microvillous surfaces.

Review: Exploration of placentation from human beings to ocean-living species

This review covers four topics. 1) Placental pathology in Himalayan mountain people. To determine morphological changes of the placenta at high altitude, pathological examination was made of 1000 Himalayan placentas obtained in Nepal and Tibet and the results compared with Japanese placentas delivered at sea level. Characteristic findings in the placental villi of the Himalayan group included high incidences of villous chorangiosis and chorangioma. These processes were clarified by ultrastructural observation. 2) Placentation in Sirenians. The giant Takikawa sea cow, which lived 5 million years ago, was discovered on Hokkaido, Japan. It was an ancestor of the dugong as well as the manatees. Sirenia, the sea cow group, shares a common ancestor with Proboscidea, the elephants, even though they now inhabit quite different environments. A comparison was made of their zonary endothelial type of placentation. 3) Placentation in sharks and rays. The remarkable placentation of hammerhead sharks and manta rays is described. 4) Placentation in the Antarctic minke whale. Placental tissue samples of this whale were obtained from the Japan Institute of Cetacean Research. In an ultrastructural study of the utero-placental junction, microfilamental processes of the allantochorionic zone and crypt formation were visualized.

Overexpression of microRNA‐542‐3p attenuates the differentiating capacity of endometriotic stromal cells

Endometriosis is defined as the presence of endometrial glandular and stromal cells outside of the uterine cavity. A previous study reported that microRNA (miR)‐542‐3p plays a critical role in eutopic endometrial decidualization. This study aims to clarify the potential role of miR‐542‐3p and the target gene, IGFBP‐1 (insulin‐like growth factor‐binding protein 1), in the impairment of the decidualizing capacity of human ectopic endometrial stromal cells (HEcESCs).

A Novel Technique for Observing the Internal Ultrastructure of Human Chromosomes with Known Karyotype

Observation of the internal ultrastructure of human chromosomes by transmission electron microscopy (TEM) has frequently been attempted in spite of the difficulties in detaching metaphase chromosome spreads from the glass slide for further processing. In this study we have used a method in which metaphase chromosome spreads were prepared on a flexible thermoplastic membrane (ACLAR) film. To assess chromosome identity, a diamidino-phenylindole staining and karyotying was first done using a conventional cytogenetic system. The chromosome spreads were then fixed with 1% osmium tetroxide, stained with freshly prepared 2% tannic acid, dehydrated, and flat-embedded in epoxy resin. The resin sheet was easily detachable and carried whole chromosome spreads. By this method, TEM observation of chromosomes from normal human lymphocytes allowed a thorough examination of the ultrastructure of centromeres, telomeres, fragile sites, and other chromosomal regions. Various ultrastructural patterns including thick electron dense boundaries, less dense internal regions, and extended chromatin loops at the periphery of the chromosomes were discernible. Application of the present method to chromosome research is expected to provide comprehensive information on the internal ultrastructure of different chromosomal regions in relation to function.