芦荟大黄素对T淋巴细胞增殖和细胞[Ca2+]i变化的影响

目的研究芦荟大黄素对植物血凝素(PHA)引起的大鼠T淋巴细胞增殖和细胞内Ca2 浓度([Ca2 ]i)变化的影响,探讨芦荟大黄素对T淋巴细胞增殖的作用和机制。方法采用MTT法检测细胞增殖,用单细胞钙成像系统记录细胞胞浆[Ca2 ]i。结果芦荟大黄素对PHA引起的细胞增殖有显著抑制作用,且其抑制作用与剂量有关;加入PHA引起细胞[Ca2 ]i迅速升高,并持续维持高[Ca2 ]i水平,芦荟大黄素对PHA引起的[Ca2 ]i升高有显著抑制作用,其作用途径包括阻断胞内Ca2 释放和抑制胞外Ca2 内流。结论芦荟大黄素可抑制T淋巴细胞增殖,其作用机制可能与抑制淋巴细胞内[Ca2 ]i升高相关。     

In vitro antiproliferative and cytotoxic activities of novel kojic acid derivatives: 5-benzyloxy-2-selenocyanatomethyl- and 5-methoxy-2-selenocyanatomethyl-4-pyranone

Some kojic acid (KA) derivatives and selenium containing compounds possess antiproliferative properties. The present study tested novel selenocyanatomethyl derivatives of KA for growth inhibitory and LDH cytotoxic activities. Human skin carcinoma (A431) and human breast carcinoma (MCF7) cells were treated with 5-benzyloxy-2-selenocyanatomethyl-4-pyranone (P763) and 5-methoxy-2-selenocyanatomethyl-4-pyranone (P764) in selected concentrations for 24, 48 and 72 h. Cell viability tests aimed at intracellular injury of mitochondria (MTT) and lysosomes (neutral red uptake, NR) revealed (a) higher growth inhibitory activity of the benzyloxy-selenocyanatomethyl derivative of KA (P763) compared with the methoxy derivative (P764) in both cell lines, (b) an intensified effect with time of exposure (MTT test only). The results demonstrate that NR cell survival/viability assay is more sensitive than the MTT test to detect subcellular changes induced by test compounds. Cell membrane integrity determined by LDH leakage confirmed an exaggerated cytotoxic effect of P763 but similar sensitivity of both cell lines to membrane injury. The ED50 values for all three tests used indicate that injury of intracellular mitochondria and lysosomes precedes the loss of membrane integrity. Cell growth inhibitory activities of new selenium containing kojic acid derivatives are preferentially aimed at the intracellular compartment rather than the plasma membrane and enlarge the group of antiproliferative active compounds.     

Blocking of intracellular ROS production by phytoglycoprotein (30 kDa) causes anti-proliferation in bisphenol A-stimulated Chang liver cells

Dioscorea batatas Decne (DBD) is traditionally used to heal inflammatory disease as a folk medicine. It was reported that a glycoprotein (DBD glycoprotein) with a molecular weight of 30 kDa was isolated from DBD and consists of carbohydrate (83.75%) and protein (16.25%) moieties. The previous results showed that it has a strong scavenging activity against hydroxyl radicals without any pro-oxidant activity in the cell-free system. The purpose of the present study was to show whether or not the DBD glycoprotein inhibits cell proliferation-related signal transduction stimulated by bisphenol A (BPA, an environmental hormone) in Chang liver cells. The results in this study indicated that DBD glycoprotein (200 microg ml(-1)) has suppressive effects on abnormal cell viability, production of intracellular reactive oxygen species (ROS) and nitric oxide (NO) in BPA (50 microM)-induced Chang liver cells by blocking the phosphorylation of mitogen-activated protein kinase (MAPK) and activating protein-1 (AP-1) activity. In addition, DBD glycoprotein (200 microg ml(-1)) normalized the activity of catalase (CAT) and glutathione peroxidase (GPx). Consequently, DBD glycoprotein inhibits the expression of proliferating cell nuclear antigen (PCNA, cell proliferation maker) stimulated by BPA. Therefore, it is speculated that DBD glycoprotein protects against carcinogenic events caused by BPA in Chang liver cells.     

Arsenic trioxide in environmentally and clinically relevant concentrations interacts with calcium homeostasis and induces cell type specific cell death in tumor and non-tumor cells

While arsenic compounds are known as environmental toxicants (especially in drinking water) and as carcinogens, some arsenic compounds, like arsenic trioxide (As2O3), are clinically used in humans to treat some forms of cancer (e.g. leukemia). Although arsenic compounds have been studied intensively, their interactions with living cells are still not fully elucidated. We have previously proposed that modulation of intracellular calcium ([Ca2+]i) homeostasis induced by As2O3 could be an important mechanism to induce cytotoxicity. Here we demonstrate, using human cell models (neuroblastoma (SY-5Y) or embryonic kidney cells (HEK)) and confocal microscopy in combination with the calcium sensitive dye fluo 4-AM, that As2O3 interferes with calcium signaling at low (environmentally and clinically relevant concentrations of 100 pM to 1 microM). Within this concentration range, As2O3 had cell type specific cytotoxic effects, with neuroblastoma cells being more sensitive to As2O3 than HEK 293. In addition, by staining with Hoechst 33347 and counting micronucleated cells as well as apoptotic nuclei, As2O3 was found to increase the rate of apoptosis and DNA damage, which was also cell type specific. These results indicate that the As2O3-induced cell death could be triggered or mediated by [Ca2+]i signals and suggest that low concentrations of As2O3 are able to interfere with specific physiological processes in diverse cell models.     

Induction of HIV-1 gag specific immune responses by cationic micelles mediated delivery of gag mRNA

In recent years, mRNA-based vaccines have emerged to be a great alternative to DNA-based vaccines due to the safety of not inserting into host genome. However, mRNA molecules are single-stranded nucleic acids that are vulnerable under RNase existing in human skin and tissues. In this study, a self-assembled cationic nanomicelles based on polyethyleneimine-stearic acid (PSA) copolymer were developed to delivery HIV-1 gag encoding mRNA to dendritic cells and BALB/c mice. We evaluated the transfection efficiency and cell uptake efficiency of naked EGFP mRNA, PSA, PEI-2k and PEI-25k nanoparticles format on DC2.4 cell lines. Immune responses after sub-cutaneous administration of gag mRNA to BALB/c mice were notably induced by PSA as compared with naked gag mRNA. We found the PSA/mRNA nanomicelles were potent systems that can effectively deliver mRNA and induce antigen-specific immune response, stimulating various new vaccine strategies using mRNA.     

单通道和全细胞记录技术

离子通道的活动是可兴奋细胞传递信息的基础,膜片钳技术的发明导致了生命科学的一场革命。对膜片钳的工作模式、记录模式、单通道和全细胞记录技术等一些重要问题作了介绍。     

Vagal Nerve Activity Recording in the Awake Condition for the Control of an Artificial Heart System

To detect useful information for an artificial heart control system, we paid attention to the autonomic nervous system. For stable recording, we used vagal nerve activity in chronic animal experiments using healthy adult goats in an awake condition because this nerve was sufficiently bold and large enough. Vagal nerve discharges were successfully recorded from awake goats. They were synchronized with respiration and responded to the hemodynamic changes induced by drug administration, suggesting that they may provide useful information for an artificial heart control algorithm. For automatic control, some time delay plays a vitally important role. Thus, predictive control for an artificial heart system may be desirable. It may be embodied by the use of autonomic nerve information.     

CD95 ligand is expressed in Reed–Sternberg cells of Hodgkin's disease

Reed-Sternberg (RS) cells and their mononuclear variants, Hodgkin's (H) cells, are considered to be the neoplastic cells of Hodgkin's disease (HD). The cellular origin of H-RS cells remains the subject of considerable controversy, although most recent papers have claimed that H-RS cells are of B cell origin. Recently, however, it has been reported that some H-RS cells express granzyme B, as observed in cytotoxic T cells and/or natural killer cells, which also express CD95 ligand (FasL/APO-1L). In the present study, the expression of CD95L and granzyme B in H-RS cells of HD was investigated. CD95L was detected in H-RS cells in five of nine HD cases (one case of lymphocyte-rich classical HD, two of these cases of nodular sclerosis type, and two of four cases of mixed cellularity type). All three examined HD cell lines expressed CD95L in the cytoplasm, although cell surface expression was seen only in L428 cells. Three HD cases expressed both CD95L and granzyme B. It was concluded that CD95L is frequently expressed in H-RS cells, which is one of their notable characteristics; albeit it seems to be irrespective of cell lineage.