Masato Yamaguchi

Purification and characterization of Microcystis aeruginosa(freshwater cyanobacterium lectin).

Microcystis aeruginosa, strain M228, a laboratory culture of freshwater cyanobacterium, showed hemagglutinating activity against rabbit, horse and human ABO erthrocytes. Crossed absorption tests revealed the presence of a single type of lectin in the extract of M228 strain cells. The lectin, termed MAL, was purified in combination with the affinity chromatography on acid-treated agarose gel and the gel permeation chromatography in an electrophoretically pure form. MAL was a glycoprotein containing 7.8% neutral sugars and was composed of a single polypeptide having a molecular weight of 57 kDa. Isoelectric point was estimated to be pH 6.4. Hemagglutinating activity of the lectin was inhibited effectively by N-acetyl-D-galactosamine and by glycoproteins. D-galactose and lactose also showed moderate inhibitory activity. The destruction of the hemagglutinating activity by a 2-mercaptoethanol treatment suggests the presence of intra-chain disulfide bond(s) essential for the activity in the molecule. The sequence of the amino-terminal region of MAL was determined as Val-Leu-Ala-Ser-Leu-Val-Ser-Thr-Ser-Gln-Ala-Gly-Ser-Leu-Glu-Leu-Leu- Ala [corrected].

An immunohistochemical study of hepatoblastoma producing human chorionic gonadotropin

High tissue concentrations of human chorionic gonadotropin (hCG) and alpha‐fetoprotein (AFP) were revealed by radioimmunoassay in a hepatic tumor which was surgically removed from a two‐year, eight‐month‐old boy manifesting sexual precocity. Histologically the tumor showed an embryonal type hepatoblastoma admixed with multinucleated tumor giant cells. The localization of native hCG and hCG‐beta subunit was immunohistochemically demonstrated in some of the above giant cells, while that of alpha‐fetoprotein was diffusely in the tumor cells of hepatoblastoma of embryonal type. Ultrastructural features of the giant cells were also presented.

Histologic characteristics of gonadotropin-producing hepatoblastoma: A survey of seven cases from Japan

Histologic studies of the human chorionic gonadotropin (hCG) producing hepatoblastoma were made for seven cases encountered in Japan. It was found in all cases that multinucleated tumor giant cells in several figures were admixed in usual hepatoblastoma tissue and one of them was confirmed to be hCG positive immunohistochemically. Round and clear cells adjacent to or separate from the giant cells showed squamoid metaplasia with occasional pearl formation. These histologic elements were highly suspected to be derivatives of choriocarcinoma and were ascertained to be characteristic of the hCG-producing hepatoblastomas. Only one among seven cases survived long after hepatic lobectomy. At the time of recurrence, none showed elevation of serum or urinary hCG level, while serum alpha-fetoprotein (AFP) level became high again. That was because recurrent tumors contained none of the characteristic elements that had been found in preceding tumors.

Multilocular lymphoepithelial cyst in the thyroid accompanied with a minute thyroid carcinoma

An aggregate (17 times 13 mm) of a few small cysts was incidentally found in the left lobe of the thyroid of a 42 year old man. The inner surface of the cysts was lined by stratified cuboidal to columnar epithelium, which showed occasional ciliation and keratinization. The cysts were densely surrounded by follicular lymphoid tissue. The lesion was designated as a multilocular lymphoepithelial cyst. Directly adjacent to the cyst‐aggregate a minute focus of papillary thyroid carcinoma (6X6 mm) existed. Tubular or papillary clusters of cancer cells were occasionally contiguous to the lining epithelium, which had penetrated through the lymphoid mantle of the cysts. Histological features of the lesion in the thyroid suggested an origin of the cysts from the developmental rest of the branchial pouch; probably from the ultimobranchial body remnant.

Thymic carcinoma of the thyroid.

A highly malignant case of intrathyroidal thymic carcinoma showing morphological and biochemical evidence identical wtth medlastlnal thymoma is presented. A 32‐year‐old female, who had previously undergone total colectomy with lleo‐proctostomy due to familial adenomatous polypnosis, was operated on for a tumor (3.4 × 4.5 cm) originating from the left thyroid lobe. A minute focus (diam. 0.8 cm) of papillary adenocarcinoma also existed in the upper pole of the right lobe. The main tumor was morphologically an epithelial thymoma with scanty lymphocyte intermixing and showed medullary differentiation with apparent Hassalls corpuscles. Mitosis was frequent and numerous tumor thrombi were in the subcapsular veins. Five months after the total thyroidec‐tomy and lymph node dissection, a subcutaneous recurrence of the tumour (dlam. 2.3 cm) appeared in the anterior cervical region. The cystic contents of the recurrent tumor revealed a high titer of thymosin α1. Other organs, including thymus, lungs, and adrenals, had all been free of neoplastic changes clinically and radiologically for 5 months after her first admission until the local tumor recurrence.