Translocation of cationic polystyrene microspheres associated with actin filaments on a surface coated with myosin motors

Muscular actin filaments can glide on a myosin-fixed glass surface by mechanochemical energy transduction. Here, we examined whether artificial objects bound to actin filaments can be translocated actively by myosin motors. Actin molecules may have a monomeric (G-actin) or fibrous form (F-actin), depending on the ionic conditions. Each form of actin molecules was mixed with a suspension of polystyrene microspheres carrying amine groups. After myosin motors were fixed on the collodion-coated glass surface, the mixture of actin molecules and microspheres was applied in the presence of adenosine triphosphate. The motion of the microspheres was monitored under a phase-contrast optical microscope. The microspheres mixed with G-actin exhibited thermal fluctuations due to insufficient binding of G-actin. In contrast, F-actin could bind to the microspheres and they were translocated in linear manner at approximately 1.5 μm/s on the myosin-coated surface. These results demonstrate that the actin filaments bound to polystyrene microspheres are capable of translocation between the actin and myosin

Tetracaine decreases intracellular Zn2+ concentration by inhibiting Zn2+ influx in rat thymocytes

In this study to examine the cytotoxic property of tetracaine, we cytometrically examined the effect of tetracaine on intracellular Zn2+ concentration by the use of FluoZin-3, a fluorescent indicator of intracellular Zn2+. Lidocaine was used as a reference drug. The incubation of rat thymocytes with tetracaine decreased the intensity of FluoZin-3 fluorescence while that with lidocaine increased the intensity. The incubation with 10 μM DTPA, a chelator for extracellular Zn2+, attenuated the tetracaine-induced decrease in fluorescence intensity. The application of ZnCl2 augmented FluoZin-3 fluorescence. The augmentation by ZnCl2 was a temperature-sensitive. Tetracaine attenuated the ZnCl2-induced augmentation of FluoZin-3 fluorescence. Taken together, the results suggest that tetracaine attenuates membrane Zn2+ influx, resulting in a decrease in intracellular Zn2+ concentration in rat thymocytes. Although the cells in this study are not targets for actions of local anesthetics, the result may give one clue to explain the difference between the cytotoxicity of local anesthetics since the action of tetracaine on FluoZin-3 fluorescence was opposite to that of lidocaine

Oxidative Stress Management in Chronic Liver Diseases and Hepatocellular Carcinoma

Chronic viral hepatitis B and C and non-alcoholic fatty liver disease (NAFLD) have been widely acknowledged to be the leading causes of liver cirrhosis and hepatocellular carcinoma. As anti-viral treatment progresses, the impact of NAFLD is increasing. NAFLD can coexist with chronic viral hepatitis and exacerbate its progression. Oxidative stress has been recognized as a chronic liver disease progression-related and cancer-initiating stress response. However, there are still many unresolved issues concerning oxidative stress, such as the correlation between the natural history of the disease and promising treatment protocols. Recent findings indicate that oxidative stress is also an anti-cancer response that is necessary to kill cancer cells. Oxidative stress might therefore be a cancer-initiating response that should be down regulated in the pre-cancerous stage in patients with risk factors for cancer, while it is an anti-cancer cell response that should not be down regulated in the post-cancerous stage, especially in patients using anti-cancer agents. Antioxidant nutrients should be administered carefully according to the patients' disease status. In this review, we will highlight these paradoxical effects of oxidative stress in chronic liver diseases, pre- and post-carcinogenesis

Management of Cirrhotic Ascites under the Add-on Administration of Tolvaptan

Tolvaptan is a recently available diuretic that blocks arginine vasopressin receptor 2 in the renal collecting duct. Its diuretic mechanism involves selective water reabsorption by affecting the water reabsorption receptor aquaporin 2. Given that liver cirrhosis patients exhibit hyponatremia due to their pseudo-aldosteronism and usage of natriuretic agents, a sodium maintaining agent, such as tolvaptan, is physiologically preferable. However, large scale studies indicating the patients for whom this would be effective and describing management under its use have been insufficient. The appropriate management of cirrhosis patients treated with tolvaptan should be investigated. In the present review, we collected articles investigating the effectiveness of tolvaptan and factors associated with survival and summarized their management reports. Earlier administration of tolvaptan before increasing the doses of natriuretic agents is recommended because this may preserve effective arterial blood volume

Nitroprusside increases intracellular Zn2+ concentration without affecting cellular thiol content : A model experiment using rat thymocytes and FluoZin-3

Nitric oxide (NO) is cytotoxic under some conditions although it has physiological roles. It is recently proposed that the cytotoxicity of NO is resulted from its interaction with glutathione and zinc. Since we have revealed that a decrease in cellular content of non-protein thiols, presumably glutathione, induces intracellular Zn2+ release, there is a possibility that the cytotoxicity of nitroprusside, a donor of NO, is resulted from the interaction of NO with cellular thiols, leading to an increase in intracellular Zn2+ concentration. To test the possibility, the effects of nitroprusside on cell lethality, intracellular thiol content, and intracellular Zn2+ concentration were examined in rat thymocytes by using a flow cytometer with propidium iodide and FluoZin-3. Nitroprusside at concentrations of 0.3 mM or more (up to 10 mM) significantly augmented FluoZin-3 fluorescence, indicating an increase in intracellular Zn2+ concentration. It was also the case under external Zn2+-free condition, suggesting nitroprusside-induced release of intracellular Zn2+. However, nitroprusside at 10 mM did not affect cell lethality and cellular thiol content. Thus, it can be concluded that nitroprusside-induced increase in intracellular Zn2+ concentration is not related to its cytotoxicity

ZnCl2 and vitamin C, known as antioxidants, differently potentiate the cytotoxicity of H2O2 in rat thymocytes : Cytometric analysis using forward and side scatters

The ‘antioxidant hypothesis’ proposes that antioxidant nutrients afford protection against chronic diseases by decreasing oxidative damages. The ability of zinc to retard oxidative processes has been recognized for many years. However, the application of ZnCl2 potentiates the cytotoxicity of H2O2. Thus, some antioxidants may be cytotoxic under certain oxidative conditions. Therefore, in this study, the effect of vitamin C, one of antioxidant nutrients, on the cells treated with H2O2 has been examined to see if vitamin C potentiates the cytotoxicity of H2O2. Experiments were carried out with flow cytometer and rat thymocytes. Vitamin C also potentiated the cytotoxicity of H2O2. The increase in cell lethality induced by the combination of H2O2 and ZnCl2 was associated with the increase in population of shrunken cells with increased intensity of side scatter. However, it was not the case for the combination of H2O2 and vitamin C. The profile of cytotoxicity induced by H2O2 and vitamin C was different from that by H2O2 and ZnCl2. It may be suggested that the effects of zinc and vitamin C varies from cytoprotective to cytotoxic, being dependent on the type of oxidative stress

History of Transcatheter Arterial Chemoembolization Predicts the Efficacy of Hepatic Arterial Infusion Chemotherapy in Hepatocellular Carcinoma Patients

This study sought to identify factors that are predictive of a therapeutic response to hepatic arterial infusion chemotherapy (HAIC) by focusing on the number of prior transcatheter arterial chemoembolization (TACE) sessions. To determine the parameters predicting a good response to HAIC, we retrospectively analyzed 170 patients with hepatocellular carcinoma (HCC) who received HAIC regimens comprising low-dose cisplatin combined with 5-fluorouracil (LFP) or cisplatin (CDDP) for the first time. In both the LFP and CDDP regimens, the response rates were significantly lower in patients with three or more prior TACE sessions than in those with two or fewer prior TACE sessions (LFP 57% versus 28%; p=0.01, CDDP 27% versus 6%; p=0.01). Multivariable logistic regression analysis revealed that the number of prior TACE sessions (≥ 3) was significantly associated with non-responder status (odds ratio 4.17, 95% Confidence Interval (CI) 1.76-9.86) in addition to the HAIC regimen. Multivariable analysis using the Cox proportional hazards model revealed that a larger number of prior TACE sessions (≥ 3) was a significant risk factor for survival (hazard ratio 1.60, 95% CI 1.12-2.29) in addition to Child-Pugh class, serum alpha-fetoprotein concentration, and maximum diameter of HCC. HCC patients who receive fewer prior TACE sessions (≤ 2) were found to be better responders to HAIC

The Early Decline of alpha-Fetoprotein and Des-gamma-Carboxy Prothrombin Predicts the Response of Hepatic Arterial Infusion Chemotherapy in Hepatocellular Carcinoma Patients

Introduction: Molecular targeting drugs are recommended as second-line treatment for intrahepatic advanced hepatocellular carcinoma (HCC). However, in Asia, hepatic arterial infusion chemotherapy (HAIC) is also considered as a second-line treatment because it improves the survival of responders. The aim of this study was to predict responders and non-responders to HAIC with low-dose cisplatin plus 5-fluorouracil (LFP) using tumor markers. Objective and Methods: The data of 47 patients who received LFP for the first time in our hospital were analyzed retrospectively. We evaluated the association between treatment response by Response Evaluation Criteria in Solid Tumors and the changing ratio of the serum concentration of alpha-fetoprotein (AFP),Lens culinarisagglutinin-reactive fraction of AFP (AFP-L3), and des-gamma-carboxy prothrombin (DCP) 2 weeks after LFP initiation. Results: The number of patients showing a complete response (CR), a partial response (PR), stable disease (SD), and progressive disease (PD) was 0 (0%), 20 (43%), 18 (38%), and 9 (19%), respectively. The AFP ratio showed significant positive correlations for PR vs. SD (p= 0.004) and PR vs. PD (p= 0.003). The DCP ratio correlated significantly for PR vs. SD (p= 0.02). The optimal cutoff values for responders were 0.79 for the AFP ratio and 0.53 for the DCP ratio. Prediction using both or either cutoff value showed 93% sensitivity, 53% specificity, a 94% negative predictive value, and a 57% positive predictive value. Conclusion: Optimal cutoff values for AFP and DCP ratios enable prediction of nonresponders to HAIC with LFP. This simple and early assessment method allows the use of HAIC and molecular targeting drugs for HCC treatment

Study on variation of neutral temperature in the polar MLT region using a sodium LIDAR at Tromsø

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日（月） 国立極地研究所 2階大会議