The hemolytic mechanism of thermostable direct hemolysin (TDH), a possible virulence factor of Vibrio parahaemolyticus, was studied. We demonstrated that TDH acts as a "pore-forming toxin" in temperature-dependent and -independent steps. The first temperature-dependent step requires only about 1-2 min incubation at 37 degrees C and makes a "pore" with a functional diameter of approximately 2 nm. The pore size was deduced from the molecular diameter of the colloidal inhibitory polysaccharides. The formation of the pores on TDH-treated erythrocyte membranes was also demonstrated by electron microscopic examination. The second step, which is a temperature-independent lytic step, causes the erythrocytes to swell owing to a colloidal osmotic influx of water via the "pores" into cells, resulting in erythrocyte lysis (or rupture) owing to increased intracellular pressure.

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ABSTRACT. Quail embryonic pectoral myoblasts fuse with each other at 35.5°C and 41°C to essentially equal extents. Whenthe myoblasts were transformed with a temperature-sensitive mutant of Rous sarcoma virus (ts-RSV), their fusion and biochemical processes of differentiation became temperature-sensitive: their fusion occurred at 41°C, the non-permissive temperature, but not at 35.5°C, the permissive temperature, suggesting that the fusion was regulated by the viral transforming gene. Fusion of the transformed cells proceeded more rapidly and synchronously than that of the parent cells at 41°C, and was completely suppressed at the permissive temperature, unlike that of the parent cells. These transformed cells were used to examine the relationship between myogenicdifferentiation and the tyrosine kinase activity of the src gene product. In spite of the temperature sensitivity of transformation, results showed that expressions of the src gene at 35.5°C and 41°C were similar. However, the level of tyrosine-phosphorylated protein was decreased at 41°C. Moreover, myoblast fusion could occur at 35.5°C in the presence of herbimycin A, an inhibitor of the tyrosine kinase activity of the src gene product. These results indicate that the tyrosine kinase activity of the src gene product is closely associated with regulation of myogenicdifferentiation of the cells.Myogenesis involves various biochemical and morphological differential events. These events are distinct and can be seen even in vitro using established line cells derived from myoblasts. Manyworkers have thus used myogenic cells as models in studies on the regulation of differentiation (23,32,39,40). Biochemical differentiations of myoblasts have been studied especially extensively from an early stage of muscle research. Myogenic differentiation is of interest not only with respect to characteristic biochemical events, but also with respect to cell fusion. We have been studying artificial cell fusion induced by HVJ(Sendai virus) and have examined changes of the membrane induced by the virus (18-20). For comparison with this artificial cell fusion, we examined the process of myotube formation, one of the sequential processes in muscle differentiation, to obtain more information on the phenomenonof cell fusion at molecular and cellular levels.During myogenesis, myoblasts proliferate and become aligned and committed to differentiation, and then they fuse simultaneously with each other in a socalled 'fusion burst' (39). There have been many studies on myoblast fusion by various experimental approaches (6, 8, 9, ll, 21, 22, 25, 38), butitsmechanismisstillobscure. Onereason for this seems to be that no suitable experimental system in which the fusion reaction can be controlled is available. Hitherto, the mechanismof myoblast fusion has mainly been studied using established cell lines derived from myoblasts, such as the L6 rat myoblast line, and the fusion reaction has been controlled with calcium. Calcium, however, is associated not only with various physiological react...

Gallbladder small cell carcinoma (SCC) comprises only 0.5 % of all gallbladder cancer and consists of aggressive tumors with poor survival outcomes against current treatments. These tumors are most common in elderly females, particularly those with cholecystolithiasis. We report the case of a 79-year-old woman with gallbladder small cell carcinoma. The patient had intermittent right upper quadrant abdominal pain and was admitted to our hospital due to suspected acute cholecystitis. She regularly received medical treatment for diabetes, hypertension, and dyslipidemia. On initial laboratory evaluation, the levels of aspartate aminotransferase (AST), total bilirubin, and C-reactive protein (CRP) were markedly elevated. She underwent computed tomography (CT) for screening. CT images showed a thick-walled gallbladder containing multiple stones and multiple 3-cm-sized round nodular lesions, which were suggestive of metastatic lymph nodes. After percutaneous transhepatic gallbladder drainage was performed, endoscopic ultrasound-guided fine needle aspiration of enlarged lymph nodes resulted in a diagnosis of small cell carcinoma or adenocarcinoma. However, we could not identify the primary lesion before the surgery because of no decisive factors. We performed cholecystectomy because there was a possibility of cholecystitis recurrence risk and also partial liver resection because we suspected tumor invasion. The final pathological diagnosis was neuroendocrine carcinoma of the gallbladder, small cell type. The tumor stage was IVb, T3aN1M1. The patient died 13 weeks after the surgery. In the present paper, we review the current available English-language literature of gallbladder SCC.

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Background. Expression of oncofetal fibronectin (oncFN) and normal fibronectin (norFN) in colorectal cancer specimens was examined to investigate the correlation between fibronectin localization and histologic grade, liver metastasis, and prognosis. Methods. Immunohistochemical staining of oncFN and norFN was performed on 99 primary lesions and 12 liver metastases of colorectal cancer. The expression of norFN and oncFN was evaluated by grading the intensity of staining as negative, positive, or strongly positive. Results. Positive staining for oncFN correlated positively with increasing stage. The rate of strongly positive staining for oncFN was 53% for primary lesions with liver metastasis, significantly higher than the oncFN‐positive rate of 13% for metastasis free cases (P < 0.05). Liver lesions had an oncFN‐positive rate of 92%. The postoperative 5‐year survival rate for 51 cases classified as Dukes Stage C was 77.8% for oncFN‐negative cases, 36.5% for oncFN‐positive cases, and 22.2% for oncFN‐strongly positive cases; these rates were significantly different (P < 0.01). Conversely, there was no correlation between norFN and any clinical variable. Conclusion. Expression of oncFN is correlated with a poor prognosis of Dukes C colorectal cancer and may serve as a useful postoperative prognostic sign. Cancer 1995;75:2802–8.

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