Kazumi Shiraiwa

Mizoribine Ameliorates the Tubulointerstitial Fibrosis of Obstructive Nephropathy

Mizoribine has been shown to possess an immunosuppressive action that inhibits the proliferation of lymphocytes selectively by interfering with inosine monophosphate dehydrogenase. Recent studies have demonstrated that mizoribine improves renal tubulointerstitial fibrosis in the rat model of unilateral ureteral obstruction (UUO) by inhibiting the infiltration of macrophages. We, therefore, examined the dose dependency of the suppressive effect of mizoribine on the infiltration of interstitial macrophages and T lymphocytes and the interstitial volume in UUO-treated kidneys. Furthermore, we investigated the expression of osteopontin (OPN), known to be a chemoattractant protein for macrophages, in the renal cortex. In rats with UUO, the interstitial volume was markedly expanded, and macrophage and T lymphocyte infiltration in the interstitium and the expression of OPN in the cortical tubules were greatly increased. Treatment with mizoribine ameliorated the increase in interstitial volume induced by UUO. Interstitial infiltration of macrophages and T lymphocytes was dose dependently suppressed by mizoribine, and the decreased macrophage infiltration was correlated with inhibition of tubular OPN expression. These results suggest that mizoribine has a beneficial effect on several steps contributing to the progression of tubulointerstitial fibrosis caused by obstruction of the ureter.

TRANSPLANTABLE OSTEOSARCOMAS WITH HIGH LUNG METASTATIC POTENTIAL IN FISCHER 344 RATS

Both spontaneous (SOS) and 4‐hydroxyaminoquinoline 1‐oxide (4‐HAQO)‐induced osteosarcomas (COS) could be serially transplanted in the subcutaneous back space of syngeneic F344 rats, the success rate becoming 100% within 5 passage generations. Transplanted tumors demonstrated rapid growth and displayed high potential for metastasis to the lung in later generations. Tbus, a 100% lung metastasis rate was observed for SOS after the 20th and for COS after the 14th generation. The histological features of the primary SOS and COS were retained during serial transfer. These model systems should be useful for investigation of the biology of this very important tumor type.

Preventive Effect of 3‐Aminobenzamide on the Reduction of NAD Levels in Rat Liver Following Administration of Diethylnitrosamine

Nicotinamide adenine dinucleotide is utilized as the substrate of a chromatin‐bound enzyme, poly(ADP‐ribose) polymerase. The effects of diethylnitrosamine and/or 3‐aminobenzamide, a potent inhibitor of poly(ADP‐ribose) polymerase, on the cellular NAD levels in rat liver were investigated. 3‐Aminobenzamide (600 mg/kg) administered intraperitoneally was not detectable in the liver within 12 hr after administration; the inhibitor had a calculated half life of 90 min. Diethylnitrosamine reduced the NAD levels in rat liver in a dose‐dependent way. The NAD content reached a minimum level at 8 hr, returning to 78% of the control value after 48 hr. The reduction of the NAD levels caused by diethylnitrosamine was completely prevented when 3‐aminobenzamide was administered either simultaneously with diethylnitrosamine or 4 hr after diethylnitrosamine treatment. Furthermore, an immunohistochemical study showed that nuclear poly(ADP‐ribose) decreased 1 hr after the administration of 3‐aminobenzamide. These results suggest that inhibition of poly(ADF‐ribosyl)ation is involved in the initiation of liver carcinogenesis by diethylnitrosamine and 3‐aminobenzamide.

Possible Model of Liver Carcinogenesis Using Inhibitors of NAD+ ADP Ribosyl Transferase in Rats

The response of cellular NAD+ metabolism to DEN and/or ABA and the carcinogenesis of the liver initiated by DEN and ABA were studied in rats. The liver NAD+ level was depleted by an ip injection of 20 mg or 200 mg/kg body weight of DEN. ABA, administered ip at a dose of 600 mg/kg simultaneously with or 4 hours after DEN, prevented the depletion of NAD+ by DEN. These biochemical findings correlated with the changes of conspicuous intranuclear immunofluorescence of poly(ADP-ribose), which were studied by immunohistochemistry. When initiated by 20 mg/kg body weight DEN and 600 mg/kg ABA and then processed to selection pressure, the liver was found to be capable of developing hepatocellular carcinomas with or without PB promotion. These results suggest that the inhibition of poly(ADP-ribosylation) might lead to irreversible initiation of liver carcinogenesis by DEN in rats.

Case Report of Rat True Hermaphroditism: Colocalization of Oocytes and Granulosa and Sertoli Cells in the Germinal Cord

We describe a case of rat hermaphroditism with bilateral ovotestes. In a 7-week-old apparently male Sprague—Dawley rat, both testes were relatively small, and the right testis with a faint protrusion was somewhat round and small as compared with the left testis. Microscopically, the testes contained ovarian tissues within their tunica albugineas in conjunction with spermatogenesis in the seminiferous tubules. As bilateral changes, oocytes surrounded by granulosa-like cells were present in the seminiferous tubule-like germinal cord. Granulosa-like and Sertoli-like cells were layered together on the basal lamina, and theca interna-like cells were occasionally observed around the basal lamina. As unilateral changes, cystic dilatation of the germinal cords with eosinophilic fluid was seen in the lumen, and the theca interna-like cells appeared to be vacuolated. Immunohistochemically, the granulosa-like and Sertoli-like cells showed positive reactions for 3β-hydroxysteroid dehydrogenase (3β-HSD) and vimentin, respectively. Theca interna-like cells reacted positively to both 3β-HSD and cytochrome P-450 17α -hydroxylase. Ultrastructurally, the granulosa, Sertoli, and theca interna cells were also identified in the ovarian tissue. From these morphological characteristics, the male rat with bilateral ovotestes was diagnosed as true hermaphroditism.

Involvement of Poly(ADP-Ribosylation) Reactions in Liver Carcinogenesis of Diethylnitrosamine in Rats

Our investigations of the possible involvement of poly(ADP-ribosylation) reaction in liver carcinogenesis were initiated by the evidence indicating that poly(ADP-ribose) participates in DNA damage and repair [1,2] since induction of DNA lesions by carcinogens and their repair have been considered to be closely related to carcinogenesis [3–6]. Previously, we reported enhancement of diethylnitrosamine (DEN) initiation of liver carcinogenesis by inhibitors of NAD+ ADP-ribosyl transferase in rats [7–9]. However, evidence for the direct involvement of the poly(ADP-ribosylation) reaction in the induction of liver carcinomas was lacking. In this paper, we describe a disturbance in NAD ADP-ribosyl transferase-dependent formation of homopolymers of repeating ADP-ribose units from NAD and possible inhibition of repair of DEN damaged DNA by ABA. The foci initiated by DEN and ABA were found to be capable of development into hepatocellular carcinomas without promotion by phenobarbital (PB).

Metastatic potential of malignant fibrous histiocytoma of myxoid or giant-cell subtype in rats

We have previously reported on the induction of rat malignant fibrous histiocytomas by 4-hydroxiaminoquinoline 1-oxide. The present study describes cell number- and time-related formation of metastatic lung nodules after i.v. injection of cell suspensions containing various numbers (10(3) to 10(5)/ml) of myxoid or giant-cell subtype malignant fibrous histiocytoma cells. The metastatic potential of the myxoid subtype of rat malignant fibrous histiocytoma was significantly enhanced by i.v. injection of tumor cells selected from metastatic lung nodules and was further increased by repeating the selection procedure more than 7 times. In contrast, the growth activity of subcutaneous transplants of tumor fragments obtained from metastatic lung nodules derived from myxoid subtype did not differ from that of parent malignant fibrous histiocytomas.

Ileal atresia and absence of appendix.

A case of ileal atresia with absence of vermiform appendix in a female newborn is reported. At the region about 105 cm from the Treitzs arch, intestinal atresia was observed with an associated V‐shaped deformity of the mesentery. Polyp‐like protuberance was observed in the area a few centimeters from the blind end of the distal intestine. Histologically, keratinizing squamous cells, bile pigments, lanugo hair, and alcian‐blue stained materials and cells were observed in the serosal layer of the tip of the proximal blind segment and mesenterium connecting to this portion. Thrombi were not observed in the mesenterium connecting to the proximal blind segment, gap segment, and distal blind segment. Squamous cells and lanugo hair were found in the green meconium taken from the large intestine. Polyp‐like protuberance was surfaced by normal intestinal mucosa, and in its inside there were two layers consisting of folded muscular tissue. In this report, we describe the detailed pathology of ileal atresia and discuss its possible cause. ACTA PATHOL. JPN. 36: 1403–1410, 1986.

A Case of Olfactory Neuroblastoma Induced in A Rat by N-Nitrosobis(2-hydroxypropyl)amine

N-nitrosobis(2-hydroxypropyl)amine (BHP) is a well-known carcinogen and induces tumors in various tissues. In the present paper, a case of olfactory neuroblastoma (ONB) induced in a rat by BHP is described. The tumor was observed in one out of 25 male rats that received 2000 ppm of BHP in drinking water from 6 to 18 weeks of age and were sacrificed at 26 weeks of age. Histologically, the tumor arose in the posterior nasal cavity and consisted of small round cells and elongate cells with scant basophilic cytoplasm. The neoplastic cells proliferated with compartmentalization into the lobules by fibrovascular septa. True rosettes, pseudorosettes and an intercellular fibrillar matrix were occasionally observed. Immunohistochemically, the tumor cells were positive for NF120/200 and β III-tubulin. These results indicate that the present tumor is the first case of ONB induced in a rat by BHP treatment.

Protective effect of liposome-encapsulated superoxide dismutase on acetaminophen-induced rat hepatocellular necrosis.

アセトアミノフェン(APAP)によるラット群細胞壊死誘発に対するliposome封入superoxide dismukase (LSOD)の防御効果について検討し,APAPの肝毒性発現機序における酸化性ストレスの関与についての知見を得た.APAPにより誘発される解細胞壊死は,LSODの同時投与によりその用量に依存して防御され,64,000U/kg体重以上のLSODにてほぼ完全に防御された.更に,APAPによる肝細胞壊死誘発に先行して,肝における脂質過酸化反応が検出され,LSODはこの反応を抑制した.一方,LSODは,APAP投与後の代謝を反映する肝組織中の還元型グルタチオン(GSH)の枯渇およびAPAP代謝物の細胞内高分子との共有結合生成には影響を与えなかった.以上の結果より,APAPの肝細胞障害発現過程への酸化性ストレスの関与が示唆され,その障害防御に対するLSODの有効性が示された.