Nucleic acid with guanidinium modification exhibits efficient cellular uptake.
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DNA↗
Biomedical subjects
Naoko Sasaki
Publications and source records attributed to Naoko Sasaki.
Ca2+ clearance mechanisms in neurohypophysial terminals of the rat.
The importance of intracellular calcium ([Ca2+]i) in the release of vasopressin (AVP) and oxytocin from the central nervous system neurohypopyhysial nerve terminals has been well-documented. To date, there is no clear understanding of Ca2+ clearance mechanisms and their interplay with transmembrane Ca2+ entry, intracellular [Ca2+]i transients, cytoplasmic Ca2+ stores and hence the release of AVP at the level of a single nerve terminal. Here, we studied the mechanism of Ca2+ clearance in freshly isolated nerve terminals of the rat neurohypophysis using Fura-2 Ca2+ imaging and measured the release of AVP by radioimmuno assay. An increase in the K+ concentration in the perfusion solution from 5 to 50 mM caused a rapid increase in [Ca2+]i and AVP release. Returning K+ concentration to 5 mM led to rapid restoration of both responses to basal level. The K+-evoked [Ca2+]i and AVP increase was concentration-dependent, reliable, and remained of constant amplitude and time course upon successive applications. Extracellular Ca2+ removal completely abolished the K+-evoked responses. The recovery phase was not affected upon replacement of NaCl with sucrose or drugs known to act on intracellular Ca2+ stores such as thapsigargin, cyclopiazonic acid, caffeine or a combination of caffeine and ryanodine did not affect either resting or K+-evoked [Ca2+]i or AVP release. By contrast, the plasma membrane Ca2+ pump inhibitor, La3+, markedly slowed down the recovery phase. The mitochondrial respiration uncoupler, carbonyl cyanide 3-chlorophenylhydrazone (CCCP), slightly but significantly increased the basal [Ca2+]i, and also slowed down the recovery phase of both [Ca2+]i and release responses. In conclusion, we show in nerve terminals that (i) Ca2+ extrusion through the Ca2+ pump in the plasma membrane plays a major role in the Ca2+ clearance mechanisms of (ii) Ca2+ uptake by mitochondria also contributes to the Ca2+ clearance and (iii) neither Na+/Ca2+ exchangers nor Ca2+ stores are involved in the Ca2+ clearance or in the maintenance of basal [Ca2+]i or release of AVP.
Animals↗
Cytotoxicity of flavonoids toward cultured normal human cells.
The cytotoxicity of flavonoids, including apigenin, eriodictyol, 3-hydroxyflavone, kaempherol, luteolin, naringenin, quercetin, rutin, and taxifolin, toward cultured human normal cells, i.e., human lung embryonic fibroblasts (TIG-1) and human umbilical vein endothelial (HUVE) cells, was examined. When these normal human cells were incubated with each flavonoid in culture medium for 24 h, some of the flavonoids showed considerable cytotoxicity at relatively high concentrations and in a dose-dependent manner. 3-Hydroxyflavone, luteolin, and apigenin were more toxic toward TIG-1 cells than the other flavonoids, and luteolin, 3-hydroxyflavone, and quercetin were more toxic toward HUVE cells. HUVE cells were more vulnerable to flavonoid cytotoxicity than TIG-1 cells. Using 2',7'-dichlorofluorescin diacetate (DCF-DA), the intracellular reactive oxygen species (ROS) level of flavonoid-treated TIG-1 cells was examined. The ROS level increased significantly in the presence of the flavone apigenin or luteolin or the flavonol 3-hydroxyflavone, quercetin, or kaempherol. These results suggest that these flavones and flavonols exert cytotoxicity through increasing intracellular ROS levels. Further, the incorporation of apigenin, 3-hydroxyflavone, luteolin, and quercetin, which are more toxic, into TIG-1 cells during 24-h incubation was examined. These flavonoids were incorporated into them and the order of their incorporation efficiency was similar to that of their cytotoxicity. In conclusion, some flavonoids are cytotoxic at higher concentrations toward human normal cells. Further, it is suggested that they are incorporated into cells, increase intracellular ROS levels, and then exert cytotoxicity.
Cell Survival↗
Protective effects of flavonoids on the cytotoxicity of linoleic acid hydroperoxide toward rat pheochromocytoma PC12 cells.
The protective effects of nine flavonoids, including apigenin, eriodictyol, 3-hydroxyflavone, kaempherol, luteolin, quercetin, rutin, and taxifolin (Table 1), on the cytotoxicity of linoleic acid hydroperoxide (LOOH) toward rat pheochromocytoma PC12 cells were examined. The cytotoxicity was assessed by the trypan blue exclusion test and so-called MTT assay. When cells were preincubated with each flavonoid prior to LOOH exposure, quercetin, 3-hydroxyflavone, or luteolin decreased LOOH cytotoxicity toward undifferentiated cells, while only luteolin decreased efficiently LOOH cytotoxicity toward differentiated cells. On the other hand, when cells were coincubated with each flavonoid and LOOH, kaempherol, eriodictyol, quercetin, 3-hydroxyflavone, luteolin, or taxifolin decreased LOOH cytotoxicity toward undifferentiated and differentiated cells. On both preincubation prior to LOOH exposure and coincubation with LOOH, luteolin acted as the most efficiently protective agent against LOOH cytotoxicity. Further, these flavonoids showed protective effects on coincubation rather than preincubation. Flow cytometry using the fluorescence probe 2',7'-dichlorofluorescin diacetate revealed that LOOH increases the intracellular level of reactive oxygen species in undifferentiated cells in a dose-dependent manner, and that desferrioxamine mesylate suppresses the LOOH-induced increase in the level. These flavonoids suppress the LOOH-induced increase. Further, the protective effect of flavonoids on LOOH cytotoxicity correlates with the suppression of the LOOH-induced increase. These results suggest that such flavonoids are beneficial for neuronal cells under oxidative stress.
Animals↗
Diesel exhaust particle-induced cell death of cultured normal human bronchial epithelial cells.
We investigated the effect of diesel exhaust particles (DEPs) on normal human bronchial epithelial (NHBE) cells. Inclusion of DEPs in culture media was lethal to NHBE cells. NHBE cells are more susceptible to DEPs than other normal human lung cells, normal human pulmonary artery endothelial cells and normal human embryonic lung fibroblasts. DEP-induced cell death was mainly due to necrosis. Using the fluorescence probes diacetoxymethyl 6-carboxy-3',6'-diacetoxy-2',7'-dichloro-3',6'-dideoxydihydrofluorescinate and 4,5-diaminofluorescein diacetate, it was observed that hydrogen peroxide and nitrogen monoxide, respectively, were generated within DEP-exposed NHBE cells. DEP cytotoxicity increased or decreased with an increase or decrease in the cellular level of reduced glutathione (GSH) by treatment with L-buthionine-(R,S)-sulfoximine or ethyl reduced glutathionate, respectively. In addition, DEPs themselves decreased the cellular level of GSH in a dose-dependent manner. Upon exposure of NHBE cells to high concentrations of DEPs, their cellular GSH was depleted almost throughout. Further, the following agents decreased DEP cytotoxicity: 1) antioxidants 2,2,5,7,8-pentamethylchroman-6-ol, ebselen, and N,N'-bis(salicylidene)ethylenediaminomanganese(II) dihydrate (EUK-8); 2) iron ion-chelating agents disodium bathophenanthrolinedisulfonate and desferrioxamine mesylate; 3) nitrogen monoxide synthase inhibitors N(G)-nitro-L-arginine methyl ester hydrochloride and N(G)-methyl-L-arginine acetate salt; and 4) an endocytosis inhibitor quinacrine. On the basis of these observations, the mechanism of DEP cytotoxicity toward NHBE cells is discussed.
Cell Death↗
Oral findings in Noonan syndrome: report of a case.
Oral findings in a case of Noonan syndrome in an 8-year-old Japanese male are reported. Examination of the patient revealed a narrow, high-arched palate and an anterior open bite. Cephalometric measurements showed a wide gonial angle, a large mandibular plane angle, a large Y-axis and long facial height. It is suggested that the patient had a skeletal open-bite malocclusion, which included an abnormal swallowing habit.
Cephalometry↗
Flavonoids suppress the cytotoxicity of linoleic acid hydroperoxide toward PC12 cells.
The suppressive effect of flavonoids on the cytotoxicity of linoleic acid hydroperoxide (LOOH) toward rat phenochromocytoma PC12 cells was examined. The extent of cytotoxicity was shown on the basis of % survival determined by the trypan blue exclusion test. On preincubation of cells with either 3-hydroxyflavone, quercetin, or luteolin prior to LOOH exposure, the cytotoxicity was considerably suppressed. In contrast, on coincubation of cells with either eriodictyol, quercetin, kaempherol, luteolin, or 3-hydroxyflavone and LOOH, it was markedly suppressed. Regardless of incubation conditions, quercetin, 3-hydroxyflavone, and luteolin were thus more effective as protective agents against the cytotoxicity than the other flavonoids. These flavonoids further showed a suppressive effect on coincubation rather than on preincubation. These results suggest that such flavonoids are beneficial for cells under oxidative stress.
Animals↗
Interferon-gamma stimulates the expression of galectin-9 in cultured human endothelial cells.
Galectin-9 is a member of the galectin family and has been identified as an eosinophil chemoattractant produced by activated T lymphocytes. Vascular endothelial cells play an important role in the initial step of eosinophil recruitment and activation in immune and inflammatory responses. We have addressed the stimulation of galectin-9 expression in endothelial cells. Galectin-9 was detected in membrane and cytosolic fractions of human umbilical vein endothelial cells stimulated with interferon-gamma (IFN-gamma). IFN-gamma also enhanced the adhesion of human eosinophilic leukemia-1 cells to endothelial monolayers, and it was inhibited by the presence of lactose. Interleukin-4, which induces eotaxin expression, did not affect the expression of galectin-9. The in situ endothelium from patients with inflammatory diseases was found to express galectin-9. IFN-gamma-induced production of galectin-9 by endothelial cells may play an important role in immune responses by regulating interactions between the vascular wall and eosinophils.
Autoimmune Diseases↗