Jun Kanno

Melanocytes and melanosis of the oesophagus in Japanese subjects--analysis of factors effecting their increase.

Normal oesophagus specimens taken from 65 autopsy cases and surgical specimens from 127 oesophageal carcinoma cases were examined histopathologically to determine melanocyte incidence and distribution. Melanocytes were found in the epithelio-stromal junction in 7.7% of normal oesophagus specimens examined at autopsy, and in 29.9% of surgical cases with oesophageal carcinoma. Positive specimens in the latter groups, especially from pre-operatively irradiated individuals, showed a more remarkable increase of melanocytes than was evident in any of the normal oesophageal samples. There were no significant differences in incidence between males and females, or between age groups. In cases where the cancer invaded into deeper stroma, the melanocytes were mainly observed in the normal epithelium around the carcinomas. Epithelial and stromal elements of the melanotic mucosa commonly showed hyperplastic changes such as acanthosis or basal cell hyperplasia, and chronic oesophagitis. Melanocytes were observed most commonly in the lower part of the oesophagus, the site where malignant melanoma of the oesophagus, most often originates. These results strongly suggest that the melanocyte increase observed in areas of hyperplastic epithelium and chronic oesophagitis may play an important role as a precursor lesion for malignant melanoma in the oesophagus.

Tumor promoting effect of goitrogens on the rat thyroid.

To evaluate the mechanism of the promoting effect of goitrogens on thyroid tumorigenesis, well-known goitrogens having different pharmacologic action, i.e., thiourea, phenobarbital sodium (PB), potassium thi-ocyanate (KSCN), and 3,4,5,6-tctrachloro-2,4,5,7-tetraiodo-fluorescein sodium salt (Rose Bengal B, FD&C Red No. 105) (FR105) were administered to the DHPN-initiated and non-initiated F344 male rats in the drinking water for 25 weeks. Remingtons iodine deficient diet (I-dcf) was fed as a positive control. These goitrogens showed significant tumor promoting effect or promoting tendency on the rat thyroids. According to the changes in thyroid morphology and thyroid-related hormone tilers observed in the present study, we proposed to classify goitrogens at least into 2 groups, i.e., iodine deficiency-type promoters and the iodine excess-type promoters. The former contains goitrogens inducing TSH-stimulated diffuse goiter composed of uniform follicles with activated tall follicular epithelial cells, such as thiourea, KSCN and PB, and the latter contains goitrogens inducing colloid goiter composed of a mixture of colloid-rich follicles with flat follicular cells and normal-looking follicles with cuboidal follicular cells, such as FR105. This classification may be useful for the risk assessment of goitrogens.

Effect of restraint stress on immune system and experimental B16 melanoma metastasis in aged mice

An overnight restraint stress was given to young and old mice and its effect was examined in terms of the number and function of T cells and natural killer (NK) cells in spleen and patterns of lung metastasis of B16 melanoma cells. A great decrease was observed in the number and proliferative activity of splenic T cells in old mice after the stress. The decrease in young mice was rather temporary with a quick recovery. The number of NK cells in spleen was not different between young and old mice before giving the stress, but a significant decrease was observed in the old after the stress. NK activity was always much lower in old than in young throughout the experiment. The pattern of metastasis of B16 melanoma cells was different between young and old mice. Metastatic colonies in lungs were larger in number and bigger in size in young mice than in old mice. After the stress, the number increased and the size unchanged in old mice, while the size increased and the number remained unchanged in young mice. It was shown that the same restraint stress resulted in a more serious influence on the immune cells in old than in young mice and gave rise to a differential effect on the pattern of tumor metastasis between young and old mice.

ANALYSIS OF MORPHOLOGICAL FACTORS OF HEPATOCELLULAR CARCINOMA IN 98 AUTOPSY CASES WITH RESPECT TO PULMONARY METASTASIS

The morphological features of ninety‐eight autopsy cases of hepatocellular carcinoma (HCC) were analyzed in relation to pulmonary metastasis. Extra‐hepatic hematogenous metastasis was observed in 64% and lung was most frequently involved (62%). A close relationship was observed between intrahepatic vascular invasion and extrahepatic hematogenous metastasis to lungs. Portal vein‐invasion was found in 80% of cases and significant correlations were recognized between the rates of portal vein‐invasion and hepatic vein‐invasion, and between the rates of portal vein‐invasion and pulmonary metastasis. There was a close correlation among the macroscopic growth‐pattern, incidence of vascular invasion, and pulmonary metastasis, and their degrees. Namely, the expansive type HCC showed significantly lower rates of vascular invasion and pulmonary metastasis than the infiltrative or mixed type HCC. These rates were particularly low in the expansive type, single nodular subtype HCC with size of a primary tumor less than 10 cm. Significantly low rates of pulmonary metastasis and portal vein‐invasion were also noted in well‐differentiated carcinoma (Grade I or II). The existence of cirrhosis or fibrosis of liver in cases with HCC was not definitely related to the occurrence of pulmonary metastasis. It was originally clarified that invasion to the portal vein and the size of HCC played a main role in pulmonary metastasis.

Hepatic and pulmonary carcinogenicity of methylene chloride in mice: a search for mechanisms

An inhalation study utilizing over 1400 female B6C3F1 mice was undertaken to study mechanistic factors associated with liver and lung tumor induction following exposure to 2000 ppm of methylene chloride. Mice were exposed to methylene chloride (treated) or chamber air (controls) 6 h per day, for varying durations up to 104 weeks. Several interim sacrifices and stop exposures were included. Exposure to 2000 ppm methylene chloride caused an increase in liver and lung neoplasia in the absence of overt cytotoxicity. Measurement of replicative DNA synthesis done after 13, 26, 52 and 78 weeks of exposure showed a significant decrease in the hepatocyte labeling index at 13 weeks. Replicative DNA synthesis in pulmonary airways after 1, 2, 3, 4, 13 and 26 weeks of exposure to methylene chloride was significantly lower than in air-exposed controls. Likewise, the increase in tumor induction in treated mice was not associated with increased replicative DNA synthesis in liver foci or in alveolar parenchyma. The frequency and pattern of H-ras gene activation were similar in control and methylene chloride-induced liver neoplasms. Similarly, the frequency and pattern of K-ras activation in lung neoplasms were not altered by exposure to methylene chloride. Early exposure to methylene chloride for only 26 weeks was sufficient to cause an increase in lung tumors by 2 years, suggesting that methylene chloride may cause early and persistent loss of growth control in lung cells. This implies that risk management strategies should be aimed at minimizing or eliminating exposure to methylene chloride. Liver neoplasms continued to increase in incidence and multiplicity as exposure continued, suggesting that methylene chloride-induced hepatocarcinogenesis is facilitated by continuing exposure to methylene chloride. Since methylene chloride is a more potent inducer of lung than liver neoplasia, it is recommended that health risk assessment be based on the lung data. While no novel molecular lesions have been found to explain the induction of lung and liver neoplasia in mice, ongoing studies may identify other molecular changes that are important in the genesis of these neoplasms. Hence, it may be necessary to revise risk assessment and management strategies in light of future research findings.

Malignant Mixed Mesodermal Tumor of Bladderoccurring after Radiotherapy for Cervical Cancer: Report of a Case

A rare case of radiation-induced malignant mixed mesodermal tumor of the bladder is reported. A 78-year-old woman complained of hematuria, which originated from a polypoid tumor in the bladder 15 years after radiotherapy for squamous cell carcinoma of the uterine cervix. The bladder tumor recurred 9 months after resection and partial cystectomy then was performed. Histological findings revealed malignant mixed mesodermal tumor composed of carcinomatous and sarcomatous elements. The former element consisted mainly of transitional cell carcinoma with occasional foci of squamous metaplasia and glandular differentiation, while the latter consisted of spindle cell sarcoma showing partly cartilaginous and osseous differentiation. The histogenesis of malignant mixed mesodermal tumor of the bladder also is discussed.

HISTOGENESIS OF THE INTRADERMAL MELANOCYTIC TUMOR IN BDF1 MICE INDUCED BY TOPICAL APPLICATION OF 9, 10‐DIMETHYL‐1, 2‐BENZANTHRACENE (DMBA) AND 12–0‐TETRADECANOYLPHORBOL‐13‐ACETATE (TPA)

The histogenesis of the intradermal melanocytic tumor induced in the skin of 88 female BDF1 mice by DMBA and TPA is studied light‐and electron‐micro‐scopically. Four types of melanocytes were found in the mouse skin. [1] The epidermal melanocytes transiently appeared several days after topical application of DMBA. [2] Hair follicles turned into anagen phase and follicular melanocytes became apparent by week 3. [3] After week 3, intradermal melanocytes of the perifollicular melanocytic networks (PFM), which were scattered in untreated mouse skin, proliferated to form the intradermal melanocytic tumors, and 267 tumors, composed of oval melanocytes in medullary growth, were induced in all of the 19 treated mice by week 32. [4] Large dendritic melanocytes located deep in the reticular dermis, which did not participate in the formation of the tumor. Only 3 papillomas were induced in 2 of the 19. Light‐and electron‐microscopically, there was no evidence of migration of epidermal and hair follicular melanocytes into the dermis. Additionally, melanin‐producing activity in the cytoplasm of Schwann cell and perineural epithelium was observed. The histogenesis of the intradermal melanocytic tumor was closely related to the melanocytes of the perifollicular melanocytic network (PFM).

Malignant endothelioma of the aorta

An untreated case of a malignant endothelial tumour of the thoracic aorta of a 67 year-old male is reported. A tumour, 7 × 6 × 1.5 cm in size occupied the lumen of the descending thoracic aorta and two daughter lesions, 0.5 cm in diameter, were located in the abdominal aorta and the left common iliac artery. Histologically, they were composed of a surface cellular lining and a underlying necrotic mass; the former was six to ten layers of bizarre epithelioid cells thick and the latter contained much nuclear debris. Innumerable tumour emboli of epithelioid tumour cells and producing ischaemic lesions were found in various organs and tissues. Ultrastructurally, tumour cells were arranged in acinar pattern with narrow lumena and immature basement membrane. There were ultrastructural appearances interpreted as Weibel-Palade bodies and immunohistochemically factor VIII related antigen and vimentin was seen in the tumour cells.

Synergistic effects of phenobarbital and thiourea on proliferative lesions in the rat liver

To evaluate the effects of phenobarbital (PB) and thiourea (TU), alone or in combination, on proliferative lesions of the liver, thyroid and lung, male F344 rats initiated with 2000 mg/kg body weight N-bis(2-hydroxypropyl) nitrosamine (DHPN) were given diet and/or drinking water containing 0% PB/TU (group 1), 1000 ppm PB (group 2), 0.1% TU (group 3) and 500 ppm PB and 0.05% TU (group 4), from weeks 2 to 20 for 19 weeks. Group 4 showed remarkable increases in the number of hepatocellular altered foci per animal, the values being superior to the averages of groups 2 and 3. The number of thyroid proliferative lesions per animal was highest in group 3 and lowest in group 2. Lung proliferative lesions were induced in all groups, but no modifying influence on their development was evident in the combined group. The present results indicate that combined administration of PB and TU exerts synergistic enhancing effects on hepatocarcinogenesis.

INDUCTION OF MELANOGENESIS IN SCHWANN CELL AND PERINEURAL EPITHELIUM BY 9, 10‐DIMETHYL‐l, 2‐BENZANTHRACENE (DMBA) AND 12‐o‐TETRADECANOYLPHORBOL‐13‐ACETATE (TPA) IN BDF1 MICE

Six‐week‐old female BDF, mice were treated with a single topical application of DMBA followed by repeated application of TPA on the clipped dorsal skin. Several weeks after DMBA application, the intradermal melanocytes of perifollicular melanocytic network began to proliferate to form melanocytic tumors in all treated mice skin. Besides these changes, single membrane‐bound melansomes and premelanosomes were found in the cytoplasm of perineural epithelia and Schwann cells with mesaxons of the nerve bundles involved, and the melanogenic activity of the Schwann cell and the perineural epithelium of the dermal peripheral nerve bundle was discussed in terms of a common feature of neuro‐ectodermal cells.