Lack of initiation activity in rat liver of low doses of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline

It has been generally accepted that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the non-threshold theory can be challenged for cancer risk assessment in humans. Here we examined low dose carcinogenicity of a food-derived, genotoxic hepatocarcinogen, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), using an in vivo medium-term bioassay to detect initiating activity for rat hepatocarcinogenesis. With MeIQx initiation at various doses followed by administration of phenobarbital, a well known hepatopromoter, no induction of glutathione S-transferase placental form-positive foci, assessed as preneoplastic lesions, was noted at doses of 0.001-1 ppm. The results imply a no-observed effect level for hepatocarcinogenicity with this genotoxic agent.     

Urinary bladder lesions induced by persistent chronic low-dose ionizing radiation

The incidence of urinary bladder cancer in the Ukraine increased from 26.2 to 43.3 per 100 000 population between 1986 and 2001 after the Chernobyl accident. The present study was conducted to evaluate the development of radiation-dependent lesions in the urinary bladders of people living in cesium 137 (¹³⁷Cs) radio-contaminated areas of the Ukraine. Bladder urothelial biopsies from 159 male and 5 female patients were subjected to histological examination and immunohistochemical study of p38 mitogen-acti-vated protein kinase (MAPK), as well as the p50 and p65 subunits of nuclear factor kappa B (NF- k B). A pattern of chronic proliferative atypical cystitis accompanied with large areas of sclerosis of connective tissue in the lamina propria was commonly observed in all cases. Interestingly, these lesions were associated with a dramatic increase in the incidences of dysplasia/carcinoma in situ , and, moreover, small urothelial carcinomas were incidentally detected. We defined the overall condition as "Chernobyl cystitis.'Greatly elevated levels of p38, p65 and p50 expression in the urothelium were evident and the patients showed increased ¹³⁷Cs in urine. The data support conclusions from our previous studies of a critical role for increased oxidative stress in generation of urinary bladder urothelial lesions in individuals chronically exposed to low-dose ¹³⁷Cs radiation. Alterations in the p38 MARK cascade and accumulation of NF- k B subunits could be crucial early molecular events in the pathogenesis of Chernobyl cystitis. (Cancer Sci 2003; 94: 328–333)     

Significance of overexpression of metallothionein in mouse urinary bladder focal lesions induced by treatment with N-butyl-N-(4-hydroxybutyl)-nitrosamine

Metallothionein (MT) is expressed in various types of human tumors, including transitional cell carcinomas of the urinary bladder, but its biological significance remains unclear. In the present study, the role of MT in urinary bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) treatment was investigated using C57BL/6 mice. One hundred 5-week-old male C57BL/6 mice were divided into two groups, which were given drinking water with or without 0.05% BBN throughout the experimental period. Subgroups of ten animals from each group were sacrificed at weeks 5, 10, 15, 20 and 25, and urinary bladder samples were examined immunohistochemically for MT, proliferating cell nuclear antigen (PCNA) and apoptosis. MT was found to be abundant in normal-looking mucosa, but decreased with progression from precancerous lesions to invasive carcinoma in the urinary bladder obtained from BBN-treated mice. Lesions could be divided into MT-positive and negative. There was a tendency for greater MT expression in PCNA-positive lesions, while apoptosis was rather associated with MT-negativity. These data suggest that the overexpression of MT may play a role in mouse urinary bladder carcinogenesis.     

Four resected cases with basaloid carcinoma of esophagus--comparison of 5-FU-related enzymes (thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyl transferase (OPRT)) between basaloid carcinoma and squamous cell carcinoma

We reported herein four resected cases with basaloid carcinoma of the esophagus and measured the activity of 5-FU related enzymes (TS, DPD, OPRT) in cancer tissue. These activities compared with those in squamous cell carcinoma. Only one case was diagnosed as basaloid carcinoma by preoperative biopsy specimen at endoscopic examination. The esophagectomy was performed thoracoscopically in all cases, and the abdominal procedure was done with the laparoscopic approach in two cases. Anastomotic leakage occurred in one case. No case had lymph node metastasis. On the other hand, a lymphatic invasion was detected in one case, and venous invasion in two, respectively. Two cases had mediastinal lymph node recurrence. DPD activity and OPRT activity showed no difference between squamous cell carcinoma and basaloid carcinoma. On the other hand, the TS activity was significantly higher in basaloid carcinoma. From the standpoint of 5-FU-related enzyme activities, basaloid carcinoma possibly has more resistance to 5-FU than squamous cell carcinoma.     

Correlation of N-myc downstream-regulated gene 1 expression with clinical outcomes of colorectal cancer patients of different race/ethnicity

AIM: To evaluate the role of N-myc downstream-regulated gene 1 (NDRG1) expression in prognosis and survival of colorectal cancer patients with different ethnic backgrounds. METHODS: Because NDRG1 is a downstream target of p53 and hypoxia inducible factor-1α (HIF-1α),we examined NDRG1 expression together with p53 and HIF-1α by immunohistochemistry. A total of 157 colorectal cancer specimens including 80 from Japanese patients and 77 from US patients were examined. The correlation between protein expression with clinicopathological features and survival after surgery was analyzed.in colorectal tumor compared with normal epithelium in both Japanese and US patient groups. Expression of NDRG1 protein was significantly correlated with lymphatic invasion,venous invasion,depth of invasion,histopathological type,and Dukes' stage in Japanese colorectal cancer patients. NDRG1 expression was correlated to histopathological type,Dukes' stage and HIF-1α expression in US-Caucasian patients but not in US-African American patients. Interestingly,Kaplan-Meier survival analysis demonstrated that NDRG1 expression correlated significantly with poorer survival in US-African American patients but not in other patient groups. However,in p53-positive US cases,NDRG1 positivity correlated significantly with better survival. In addition,NDRG1 expression also correlated significantly with improved survival in US patients with stages Ⅲ and Ⅳ tumors without chemotherapy. In Japanese patients with stages Ⅱ and Ⅲ tumors,strong NDRG1 staining in p53-positive tumors correlated significantly with improved survival but negatively in patients without chemotherapy. CONCLUSION: NDRG1 expression was correlated with various clinicopathological features and clinical outcomes in colorectal cancer depending on the race/ethnicity of the patients. NDRG1 may serve as a biological basis for the disparity of clinical outcomes of colorectal cancer patients with different ethnic backgrounds.     

Effect of ethanol treatment on metabolic activation and detoxification of esophagus carcinogenic N-nitrosamines in rat liver

In order to elucidate the mechanism underlying enhancement by ethanol of N-nitrosodiethylamine (DEN)- and N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in rats, hepatic levels of cytochrome P-450 (CYP) enzymes, mutagenic activation of several N-nitrosamines and three kinds of UDP-glucuronyltransferase (UDPGT) activities were assayed in F344 rats. Immunoblot analyses of microsomal CYP proteins revealed induction of CYP2E1 (approximately 2-fold), but not CYP2B1/2, 1A1/2 or 3A2, by treatment with 10% ethanol in the drinking water for 2 weeks. In contrast, s.c. treatment with 0.5 mg/kg NMBA three times per week for 2 weeks produced no significant alterations in the levels of these CYP species. Ethanol treatment also elevated the mutagenic activities of N-nitrosodimethylamine (DMN), DEN and N-nitrosopyrrolidine (NPYR) in strain TA100 up to 2.1-, 1.6- and 2.3-fold above each control, respectively. However, this was not the cases for four N-nitrosamines, including NMBA, in strain TA100 and two heterocyclic amines and aflatoxin B(1) in strain TA98. In addition, ethanol did not affect UDPGT activities towards 4-nitrophenol, bilirubin and testosterone. Hepatic CYP species responsible for mutagenic activation of selected N-nitrosodialkylamines were confirmed by use of specific CYP inducers and inhibitors with the liver from F344 and Wistar rats, indicating that DMN, DEN and NMBA are selectively activated by CYP2E1, predominantly by CYP2E1 with a slight contribution by CYP2B2 and selectively by CYP2B1/2, respectively. These results demonstrate that ethanol exerts an enhancing effect on mutagenic activation by CYP2E1 of DMN, DEN and NPYR, but does not affect that of NMBA and the other carcinogens by CYP2B1/2, 1A1/2 and 3A2 and UDPGT1A1, 1A6 and 2B1 activities. Consequently, this suggests that enhancement by ethanol of DEN-induced esophageal carcinogenesis in F344 rats can be attributed to an increase in hepatic activation during the initiation phase, but that of NMBA-induced tumorigenesis is not attributable to metabolic activation and inactivation via glucuronidation in liver.     

Effectiveness of Prehospital Epinephrine Administration in Improving Long-term Outcomes of Witnessed Out-of-hospital Cardiac Arrest Patients with Initial Non-shockable Rhythms

Objective: We evaluated the association between prehospital epinephrine administration by emergency medical services (EMS) and the long-term outcomes of out-of-hospital cardiac arrest (OHCA) with initial pulseless electrical activity (PEA) or asystole. Methods: We conducted a controlled, propensity-matched, retrospective cohort study by using Japan's nationwide OHCA registry database. We studied 110,239 bystander-witnessed OHCA patients aged 15–94 years with initial non-shockable rhythms registered between January 2008 and December 2012. We created 1–1 matched pairs of patients with or without epinephrine by using sequential risk set matching based on time-dependent propensity scores to balance the patients' severity and characteristics. We compared overall and neurologically intact survival 1 month after OHCA between cases and controls using conditional logistic regression models by category of the initial rhythm. Results: Propensity matching created 7,431 pairs in patients with PEA and 8,906 pairs in those with asystole. Epinephrine administration was associated with higher overall survival (4.49% vs. 2.96%; odds ratio [OR], 1.55; 95% confidence interval [CI], 1.30–1.85) but not with neurologically intact survival (0.98% vs. 0.78%; OR, 1.26; 95% CI, 0.89–1.78) in patients with PEA, and with higher overall survival (2.38% vs. 1.04%; OR, 2.34; 95% CI, 1.82–3.00) and neurologically intact survival (0.48% vs. 0.22%; OR, 2.28; 95% CI, 1.31–3.96) in those with asystole. Conclusions: Prehospital epinephrine administration by EMS is favorably associated with long-term neurological outcomes in patients with initial asystole and with long-term survival outcomes in those with PEA.     

Plasma levels of atrial natriuretic peptide in patients with liver cirrhosis and its relation to ascites and renal function

Plasma immunoreactive a-human atrial natriuretic polypeptide (Ir-α-hANP) was measured by radioimmunoassay in 21 cirrhotics and 10 normal subjects. Average of Ir-α-hANP level in cirrhotics was significantly higher than in normal subjects (125.8 ± 79.6 versus 28.7 ± 12.2 pg/ml, P< 0.001). In cirrhotics without ascites, Ir-α-hANP levels were positively correlated with creatinine clearance (Ccr) and urinary sodium excretion, suggesting that α-hANP was closely related to renal circulation and sodium homeostasis. One the contrary, in cirrhotics with ascites Ir-α-hANP levels were negatively correlated with Ccr. Urinary sodium excretion in cirrhotics with ascites and Ccr more than 50 ml/min was positively correlated with Ir-α-hANP levels. However, cirrhotics with ascites and Ccr less than 50 ml/min excreted little sodium in spite of high Ir-α-hANP levels. On the basis of the Ir-α-hANP before and after treatment of ascites, cirrhotics with ascites were subdivided into 2 groups. In group I Ir-α-hANP decreased from high values and in group II it was further elevated from slightly high values by treatment. The difference in renal function and plasma volume may account for the difference in Ir-α-hANP changes in the 2 groups. This study was presented in part in the 22nd meeting of the Japanese Association for the Study of the Liver, June 6,1986, Tokyo, Japan and in 22nd meeting of the European Association for the Study of the Liver, September 5, 1987, Torino, Italy.