Induction of tumors in the Japanese house musk shrew, Suncus murinus (Insectivora), by dimethylbenz[a]anthracene

The carcinogenic effect of 7,12-dimethylbenz[a]anthracene (DMBA) was examined in the virgin female Japanese house musk shrew, Suncus murinus (family: Soricidae, order: Insectivora). Leukemia, musk gland tumors, pilosebaceous tumors and sarcomas were induced in the DMBA-treated shrews, whereas none of the controls developed any tumors up to 50 weeks of age. DMBA emulsion was administered i.p. at a dose of 1.25 or 2.5 mg once a week, with either four or eight doses being given from 8 weeks of age. Leukemia developed in 100% (9/9), 50% (5/10), 56% (5/9) and 0% (0/10) of the animals treated with a total dose of 20 mg (8 x 2.5 mg), 10 mg (8 x 1.25 mg), 10 mg (4 x 2.5 mg) and 5 mg (4 x 1.25 mg) of DMBA respectively. Leukemia was of the lymphatic and/or mast cell type, and the spleen was the organ invariably involved. A dose-dependent effect of DMBA was not observed for pilosebaceous and musk gland tumors. When 1 mg of DMBA powder was dusted into the subcutaneous tissue at 4 weeks of age, sarcomas developed at the dusted site (69%; 9/13).

Keratin expression in the normal breast and in breast carcinoma

The immunohistochemical reactivities of 69 cases of breast carcinoma were examined on methacarn-fixed, paraffin-embedded sections using eight different monoclonal antibodies which recognize one or a few keratin polypeptides. In the normal breast, the monoclonal antibodies RPN1162, RPN1165 and AE1 stained almost all the luminal cells but not the basal (myoepithelial) cells. The monoclonal antibodies 35BH11, M20, CK5 and CK8.12 stained only a subset of the luminal cells. In contrast, 312C8-1 stained basal cells but not luminal cells. All the tumour specimens reacted with AE1, while over 80% of them also reacted with 35BH11 (57/69), CK5 (57/69) and RPN1165 (55/69); 30% reacted with CK8.12 (21/69) and 16% with RPN1162 (11/69). Basal cell-specific keratin, as defined by 312C8-1, was detected in only 1% of cases (1/69). Monoclonal antibodies to different keratin polypeptides may be of use in the characterization and subdivision of breast cancer.

DMBA-induced uterine vascular tumors in BALB/c mice: ovary-dependent carcinogenic response

Female BALB/c mice treated with a single intraperitoneal injection of 1 mg of 7, 12-dimethylbenz(a)anthracene (DMBA) at 4, 8 and 20 weeks of age showed a high incidence of uterine vascular tumors. Bilateral ovariectomy preceding DMBA treatment almost completely inhibited the induction of vascular tumors, while ovariectomy following DMBA treatment resulted in endometrial gland atrophy and a high incidence of vascular tumors. Vascular tumors were also induced when DMBA was given to neonatal androgenized mice, whereas among neonatal androgenized and normal female mice not treated with DMBA the incidence was 0%. Histological examinations revealed benign hemangiomas or angiosarcomas. In contrast, DMBA-treated male BALB/c mice and orchiectomized mice, and DMBA-untreated males showed no vascular tumors. A striking ovarian dependence of induction of uterine vascular tumors was observed.

[An autopsy case of multiple myeloma accompanied by extensive nodular infiltration into the extraskeletal tissue]

Discussed is the case of a 41-year-old Japanese man dead at 4 months after start of his clinical course of multiple myeloma of the Bence-Jones protein lambda type of the skull. Autopsy findings revealed that atypical plasmacytes had infiltrated extensively into the testes, the retroperitoneum, including the pancreas and the renal pelvis, the bilateral pleura, the right subclavian soft tissue, and the meningism, but not to the liver, spleen, and lymph nodes. In both testes, which weighted 120 g and 100 g, respectively, myeloma cells were found disseminated throughout the testicular tissue. Such a testicular involvement in cases of a multiple myeloma is extremely rare. The pertinent literature also is reviewed.

[An autopsy case of postirradiation cutaneous angiosarcoma of the hip]

Presented is the case of a 63-year-old woman who developed a cutaneous angiosarcoma of the hip after receiving adjuvant radiation therapy for a squamous cell carcinoma of the uterine cervix after a hysterectomy. The time lapse between the radiation therapy and the occurrence of the angiosarcoma was 15 years, and its systemic metastasis was seen on autopsy. This autopsy was carried out 26 years after the patient had received the initial irradiation and no recurrence of the uterine cancer was found. Factor involved in the etiology of an angiosarcoma are discussed, and 34 previously reported cases of a postirradiation angiosarcoma are reviewed.

Microvesicular fatty liver in rats with resembling Reye's syndrome induced by 4-pentenoic acid

To produce an animal model of Reye's syndrome (RS), 20 adult male Wistar rats were given 10 repeated i.p. injections of 50 mg/kg 4-pentenoic acid (PA) each separated by an 8-h interval. Then, 90 min after the tenth dose, they were given a final i.p. injection of 150 mg/kg PA. Thirteen control animals were injected with vehicle only using the same time schedule. More than half the animals in each group were fed a common diet, but the others were fasted during the terminal 10-h stage. All rats were sacrificed 30 min after the last injection. At the terminal stage, in comparison with the vehicle-injected controls, hypolipemia, hypoglycemia and high titers of serum ammonia and urea N were estimated significantly in the PA-treated rats fed throughout the whole period. Hypolipemia and hypoglycemia were more prominent in the terminally fasted group than the group fed continuously. Only in the PA-treated rats fed throughout the whole period moderate morphological signs of microvesicular fatty liver were exhibited. Ultracytochemical findings and biochemical determinations showed that the major lipids in the microvesicular fatty livers were triglycerides. Morphometric analysis revealed distinct hepatic mitochondrial swelling in the PA-treated rats. Therefore, the above treatment with PA was able to induce microvesicular fatty liver in rats with resembling RS, which were fed throughout the treatment procedure, but not in the terminally fasted rats.

Immunolocalization of the human basal epithelial marker monoclonal antibody 312C8-1 in normal tissue and mammary tumours of rodents

Using immunoperoxidase staining of monoclonal antibody 312C8-1 against 51,000 dalton human keratin polypeptide, immunolocalization was observed in frozen sections of normal tissue and mammary tumours of adult female mice and rats. In normal tissue, the epitope was recognized in myoepithelial cells of the mammary, sweat and salivary glands, and in basal and suprabasal cells of the epidermis. However, the antibody did not react with luminal epithelial cells of the above glands or with mesenchymal cells. In spontaneous mammary tumours of mice, marker-positive tumour cells were distributed only in the outer layer of adenocarcinoma Type A, while they were scattered in some foci of adenocarcinoma Type B, and encircled the epithelial foci of pregnancy dependent tumours (plaque). All layers of epidermoid structures in adenoacanthoma revealed positivity. In rat mammary tumours induced by local dusting with 7, 12-dimethylbenz(a)anthracene (DMBA) powder, the staining pattern of benign tumours was comparable to that of the normal mammary gland. But, in addition to basally situated cells, marker-positive tumour cells were found scattered in the foci of adenocarcinoma, and were not restricted to basal cells in squamous cell carcinoma. The marker was not found in sarcomatous tissue. This antibody can therefore also be applied to rodents, and the staining pattern can be used to identify the epithelial subclass specific marker in normal tissue and in mammary tumours.