Effect of oestrone on membrane fluidity of erythrocytes is mediated by a nitric oxide-dependent pathway: An electron paramagnetic resonance study

1. It has been recognized that hormone replacement therapy (HRT) may have a beneficial effect on protection against cardiovascular diseases. Oestrone is the major component of conjugated equiline oestrogens, which are commonly used in HRT. The present study was performed in order to investigate the effects of oestrone on the membrane fluidity of erythrocytes by means of an electron paramagnetic resonance (EPR) and spin-labelling method. 2. In an in vitro study, oestrone significantly decreased the order parameter (S) for 5-nitroxide stearate (5-NS) and the peak height ratio (ho/h-1) for 16-nitroxide stearate (16-NS) obtained from EPR spectra of erythrocyte membranes. This finding indicated that oestrone may increase the membrane fluidity and improve the membrane microviscosity of erythrocytes. 3. The effect of oestrone was significantly potentiated by the nitric oxide (NO) donor s-nitroso-N-acetylpenicillamine and the cGMP analogue 8-bromo-cGMP. 4. In contrast, the change in membrane fluidity induced by oestrone was antagonized by the NO synthase inhibitors NG-nitro-l-arginine methyl ester and asymmetric dimethyl-l-arginine. 5. The results of the present study show that oestrone significantly increases membrane fluidity and improves the rigidity of cell membranes, which is partially mediated by a NO- and cGMP-dependent pathway. Furthermore, the data may be consistent with the hypothesis that oestrone could have a beneficial effect on the rheological behaviour of erythrocytes and have a crucial role in the regulation of the microcirculation.     

Detection of oxidant-induced slight chromosomal damage in cells by subsequent exposure to X-rays

We examined whether slight oxidative stress and/or damage in cells could be amplified by subsequent ionizing irradiation and thus become detectable as obvious chromosomal damage. WIL2-NS cells, a human B lymphoblastoid cell line, were pretreated with an oxidant and then exposed to X-rays at 0.25 or 0.5 Gy. The chromosomal damage in the cells was evaluated by cytokinesis-block micronucleus (CBMN) assay. Pretreatment with a superoxide-generating system (hypoxanthine (HX)/xanthine oxidase (XO), 1 and 2 mU/ml of XO), tert-butyl hydroperoxide (t-BuOOH, 10 and 100 microM) or H2O2 (5 microM) alone did not induce significant chromosomal damage, but the oxidant-induced damage increased significantly with subsequent irradiation. The tested dose of these oxidants did not induce significant changes in cell viability, the nuclear division index, and the concentration of antioxidants, indicating that only weak oxidative stress was introduced into the cells. These results suggest that low-dose oxidant-induced chromosomal damage becomes detectable as obvious chromosomal damage with subsequent ionizing irradiation in vitro.     

Neurotoxicity induced by tacrolimus after liver transplantation: relation to genetic polymorphisms of the ABCB1 (MDR1) gene

BACKGROUND: Tacrolimus is a substrate of P-glycoprotein (PGP) encoded by the multidrug resistant (MDR)1 gene (ABCB1). PGP, a multidrug efflux pump, restricts the distribution of tacrolimus in the brain. In this study, we investigate the correlation of ABCB1 gene polymorphism with tacrolimus-induced neurotoxicity in patients after liver transplantation. METHODS: The genotype of 6 patients with neurotoxic events and 11 patients without neurotoxic events was analyzed by polymerase chain reaction (PCR), and 8 mutations were detected. In addition to laboratory findings and patient characteristics, the contribution of mutations in the ABCB1 gene was evaluated with stepwise discriminant function analysis. RESULTS: High tacrolimus concentration, liver dysfunction, and mutation at position 2677 in exon 21 were demonstrated as positive predictors of tacrolimus-induced neurotoxicity. CONCLUSION: It is indicated that blood concentrations, liver function, graft weight, and polymorphism in the ABCB1 gene are important factors in tacrolimus-induced neurotoxicity.     

Dose-dependent effect of dietary conjugated linoleic acid on the growth of rat hepatoma dRLh-84 cells in vivo

In this study, the effect of varying doses of conjugated linoleic acid (CLA) on the growth of transplanted hepatoma dRLh-84 cells and the relationship between tumor growth and prostaglandin (PG) E2 production or cyclooxygenase (COX)-2 expression were examined. Donryu rats were fed an experimental diet containing 0, 0.1, 0.5, or 2 wt.% CLA for 3 wk, and then dRLh-84 cells were transplanted into the liver. Results show that dietary CLA (0.5 and 2 wt.%) significantly enhanced the growth of the transplanted hepatoma cells compared to the non-CLA diet group at 20 d after cell transplantation. Tumor weight at 10 d after transplantation was also significantly higher in the 2 wt.% CLA group than in non-CLA fed rats. Ten days after transplantation, the PGE2 level in the tumor tissue was shown to be depressed in a CLA dose-dependent manner. Cyclooxygenase-2 (COX-2) mRNA expression in the tumor also tended to be lower in the CLA group than in the non-CLA diet group 10 d after transplantation. Dietary CLA did not affect the tumor phospholipid arachidonic acid level, which is a substrate for PG synthesis. These results indicate that dietary CLA of at least 0.5 wt.% enhances the growth of transplanted dRLh-84 cells in vivo. It is believed that growth promotion of dRLh-84 cells in vivo by CLA cannot be clarified by the PG synthesis dependent mechanism.     

Reduced expression of thrombospondin-1 correlates with a poor prognosis in patients with non-small cell lung cancer

Thorombospondin-1 (TSP-1) is a 450 kDa extracellular matrix glycoprotein, with anti-angiogenic activity. We analyzed the relationship in TSP-1 expression and Microvessel count (MVC), and also clinical factors, using immunohistochemical methods for non-small cell cancer (NSCLC). Histopathologically, there was inverse correlation between TSP-1 expression and MVC for squamous cell carcinoma, but not for adenocarcinoma cases. Among 199 completely resected cases of NSCLC, the 5-year survival was 77.0% when the expression of TSP-1 was maintained and 55.1% when the expression were reduced, respectively (P=0.0046). When compared with TSP-1 expression in the high MVC subgroup, there was significantly shorter survival time when TSP-1 expression was reduced (P=0.0091), and no significant difference was seen for the low MVC subgroup. Multivariate analysis revealed that expression of TSP-1 is as a prognostic factor of NSCLC. Our present data suggest that TSP-1 might not be a direct anti-angiogenic factor and the TSP-1 expression is a prognostic indicator of NSCLC.     

Smoking-related increase of O(6)-methylguanine-DNA methyltransferase expression in squamous cell carcinoma of the esophagus

DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) has a defensive role against alkylating agents associated with increased incidence of malignant tumors. The aim of the current study was to elucidate the significance of immunohistochemical expression of MGMT in squamous cell carcinoma (SCC) of the esophagus, with a special reference to the correlation of smoking. Immunohistostaining of MGMT was performed in the specimens collected from 100 patients with SCC of the esophagus. The relationship between the personal history of smoking and MGMT expression was examined and the value of Brinkman index was compared between patients with and without MGMT expression. Fifty-five SCCs (55.0%) had a positive response to MGMT inununostaining. The proportion of patients who had tumors with MGMT expression among patients with smoking habits was 62.0% (49 out of 79), which was significantly higher than that among patients without smoking habits (28.6%, 6 out of 21; P=0.005). The mean value of Brinkman index in patients who had tumors with MGMT expression (1189+/-604) was significantly higher than that in patients who had tumors without MGMT expression (871+/-656; P=0.020). Our results suggested that MGMT expression in esophageal SCC might be correlated with smoking habits of the patients.     

Expression of the TNF-alpha gene on mouse lung carcinoma cells suppresses spontaneous lung metastasis without affecting tumorigenicity

Forced expression of TNF-alpha in tumor cells has been shown to inhibit their tumor growth in vivo through a number of mechanism such as activation of an immune system and induction of an apoptotic process. We re-examined the anti-tumor effects caused by the TNF-alpha gene transfer using high-metastatic, murine lung carcinoma A11 cells. Expressed TNF-alpha molecules remained on cell surface and were not secreted into culture supernatants in vitro. Syngeneic immunocompetent mice developed tumors of TNF-alpha-expressed A11 cells and the growth of their subcutaneous tumors was not different from that of parent tumors. Spleen of the mice that developed TNF-alpha-expressed A11 tumors was significantly larger than that of the mice bearing parent tumors, but relative ratios of each cell population were not different. In contrast to subcutaneous tumors, the number of spontaneous lung foci metastasized from the subcutaneous TNF-alpha-expressed A11 tumors was markedly reduced compared with that from parent tumors. Expressed TNF-alpha on tumors is released by matrix metalloproteinases from surrounding tissues and anti-tumor effects by TNF-alpha can be influenced by local environmental conditions.     

Pathologic features of superficial esophageal squamous cell carcinoma with lymph node and distal metastasis

BACKGROUND: Endoscopic mucosal resection (EMR) is a less invasive localized treatment for patients with esophageal carcinoma. However, indications for EMR use in cases of superficial esophageal carcinoma are controversial. The authors evaluated histopathologic risk factors for lymph node metastasis and recurrence. METHODS: In the specimens resected, the authors examined depth, the superficial area and the area attached to or infiltrating the lamina muscularis mucosa. RESULTS: The authors found that the superficial area and the attached or infiltrated area reflected the depth of the tumor. However, there was a recurrence of esophageal carcinoma even in m3 cases attached only to the lamina muscularis mucosa. CONCLUSIONS: The authors concluded that ml and m2 esophageal carcinoma had almost no risk of lymph node metastasis and recurrence no matter how extensive the superficial area. In addition, sm2 and sm3 carcinoma have a high frequency of lymph node metastasis and recurrence. M3 and sm1 carcinoma run the risk of lymph node metastasis and recurrence however small the superficial area and the area attached to or infiltrating the lamina muscularis mucosa. Treatment strategies for patients with superficial esophageal carcinoma, including EMR, should take the above findings into account.