Dendritic electrogenesis in rat hippocampal CA1 pyramidal neurons: functional aspects of Na+ and Ca2+ currents in apical dendrites

The regenerative properties of CA1 pyramidal neurons were studied through differential polarization with external electrical fields. Recordings were obtained from somata and apical dendrites in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), DL-2-amino-5-phosphonovaleric acid (APV), and bicuculline. S+ fields hyperpolarized the distal apical dendrites and depolarized the rest of the cell, whereas S÷ fields reversed the polarization. During intradendritic recordings, S+ fields evoked either fast spikes or compound spiking. The threshold response consisted of a low-amplitude fast spike and a slow depolarizing potential. At higher field intensities the slow depolarizing potential increased in amplitude, and additional spikes of high amplitude appeared. During intrasomatic recordings, S+ field evoked repetitive firing of fast spikes, whereas S÷ fields evoked a slow depolarizing, potential on top of which high- and low-amplitude spikes were evoked. Tetrodotoxin (TTX) blocked all types of responses in both dendrites and somata. Perfusion with Ca²⁺-free, Co²⁺-containing medium increased the frequency and amplitude of fast spikes evoked by S+ field and substantially reduced the slow depolarizing potential evoked by S÷ fields. Antidromic stimulation revealed that an all-or-none dendritic component was activated in the distal apical dendrites by back-propagating somatic spikes. The dendritic component had an absolute refractory period of about 4 ms and a relative refractory period of 10–12 ms. Ca²⁺-dependent spikes in the dendrites were followed by a long-lasting afterhyperpolarization (AHP) and a decrease in membrane input resistance, during which dendritic excitability was selectively reduced. The data suggest that generation of fast Na⁺ currents and slow Ca²⁺ currents in the distal part of apical dendrites is highly sensitive to the dynamic state of the dendritic membrane. Depending on the mode and frequency of activation these currents can exert a substantial influence on the input-output behavior of the pyramidal neurons. © 1996 Wiley-Liss, Inc.     

Synaptic target selectivity and input of GABAergic basket and bistratified interneurons in the CA1 area of the rat hippocampus

To assess the position of interneurons in the hippocampal network, fast spiking cells were recorded intracellularly in vitro and filled with biocytin. Sixteen non-principal cells were selected on the basis of 1) cell bodies located in the pyramidal layer and in the middle of the slice, 2) extensive labeling of their axons, and 3) a branching pattern of the axon indicating that they were not axo-axonic cells. Examination of their efferent synapses (n = 400) demonstrated that the cells made synapses on cell bodies, dendritic shafts, spines, and axon initial segments (AIS). Statistical analysis of the distribution of different postsynaptic elements, together with published data (n = 288) for 12 similar cells, showed that the interneurons were heterogeneous with regard to the frequency of synapses given to different parts of pyramidal cells. When the cells were grouped according to whether they had less or more than 40% somatic synaptic targets, each population appeared homogeneous. The population (n = 19) innervating a high proportion of somata (53 ± 10%, SD) corresponds to basket cells. They also form synapses with proximal dendrites (44 ± 12%) and rarely with AISs and spines. One well-filled basket cell had 8,859 boutons within the slice, covering an area of 0.331 mm² of pyramidal layer tangentially and containing 7,150 pyramidal cells, 933 (13%) of which were calculated to be innervated, assuming that each pyramidal cell received nine to ten synapses. It was extrapolated that the intact axon probably had about 10,800 boutons innervating 1,140 pyramids. The proportion of innervated pyramidal cells decreased from 28% in the middle to 4% at the edge of the axonal field. The other group of neurons, the bistratified cells (n = 9), showed a preference for dendritic shafts (79 ± 8%) and spines (17 ± 8%) as synaptic targets, rarely terminating on somata (4 ± 8%). Their axonal field was significantly larger (1,250 ± 180 μm) in the medio-lateral direction than that of basket cells (760 ± 130 μm). The axon terminals of bistratified cells were smaller than those of basket cells. Furthermore, in contrast to bistratified cells, basket cells had a significant proportion of dendrites in stratum lacunosum-moleculare suggesting a direct entorhinal input. The results define two distinct types of GABAergic neuron innervating pyramidal cells in a spatially segregated manner and predict different functions for the two inputs. The perisomatic termination of basket cells is suited for the synchronization of a subset of pyramidal cells that they select from the population within their axonal field, whereas the termination of bistratified cells in conjunction with Schaffer collateral/commissural terminals may govern the timing of CA3 input and/or voltage-dependent conductances in the dendrites. © 1996 Wiley-Liss, Inc.     

肝癌细胞HepG2与肝癌患者树突状细胞融合瘤苗的体外效应

目的将肝细胞癌(HCC)患者树突状细胞(DCs)与肝癌细胞HepG2融合制备瘤苗,检测其体外诱导同源T细胞产生特异性抗HepG2的免疫效应.方法以血细胞分离机分离富集HCC患者外周血单个核细胞(PBMCs),应用重组人粒细胞/巨噬细胞集落刺激因子(rhGM-CSF)、白细胞介素-4(rhlL-4)体外诱导培养DCs;聚乙二醇融合DCs与肝癌细胞HepG2,MTT法测定融合细胞(DCs/HepG2)刺激同源T淋巴细胞增殖分化能力,细胞毒性实验检测DCs/HepG2诱导细胞毒性T淋巴细胞(CTL)对HepG2的特异性杀伤作用.结果融合细胞DCs/HepG2高表达成熟DC表面分子,其中CD8390.4%,CD8087.7%,CD8684.4%,HLA-DR98.5%;其刺激同源T淋巴细胞增殖的能力显著高于HepG2和DCs;DCs/HepG2活化的CTL对HepG2具有显著杀伤作用,其杀伤率为(63.5±4.6)%(效靶比例为20∶1).结论HCC患者外周血DC融合HepG2细胞可有效诱导同源T淋巴细胞产生特异性抗HCC免疫效应,可能成为HCC免疫治疗的有效途径.     

Photodynamic therapy of melanoma with new,structurally similar,NIR-absorbing ruthenium (II) complexes promotes tumor growth control via distinct hallmarks of immunogenic cell death

Cancer therapies that generate T cell-based anti-cancer immune responses are critical for clinical success and are favored over traditional therapies. One way to elicit T cell immune responses and generate long-lasting anti-cancer immunity is through induction of immunogenic cell death (ICD), a form of regulated cell death that promotes antigenicity and adjuvanticity within dying cells. Therefore, research in the last decade has focused on developing cancer therapies which stimulate ICD. Herein, we report novel photodynamic therapy (PDT) compounds with immunomodulatory and ICD inducing properties. PDT is a clinically approved, minimally invasive anti-cancer treatment option and has been extensively investigated for its tumor-destroying properties, lower side effects, and immune activation capabilities. In this study, we explore two structurally related ruthenium compounds, ML19B01 and ML19B02, that can be activated with near infrared light to elicit superior cytotoxic properties. In addition to its direct cell killing abilities, we investigated the effect of our PSs on immunological pathways upon activation. PDT treatment with ML19B01 and ML19B02 induced differential expression of reactive oxygen species, proinflammatory response-mediating genes, and heat shock proteins. Dying melanoma cells induced by ML19B01-PDT and ML19B02-PDT contained ICD hallmarks such as calreticulin, ATP, and HMGB1, initiated activation of antigen presenting cells, and were efficiently phagocytosed by bone marrow-derived dendritic cells. Most importantly, despite the distinct profiles of ICD hallmark inducing capacities, vaccination with both PDT-induced dying cancer cells established anti-tumor immunity that protected mice against subsequent challenge with melanoma cells.     

Impact of Infectious Disease after Lactococcus lactis Strain Plasma Intake in Vietnamese Schoolchildren: A Randomized,Placebo-Controlled,Double-Blind Study

Lactococcus lactis strain Plasma (LC-Plasma) is reported to have anti-viral effects via direct activation of plasmacytoid dendritic cells, which upregulate the production of type I and III interferons. A randomized, placebo-controlled, double-blind, parallel group study was designed for elementary schoolchildren, grades 1 to 3, in Vietnam. LC-Plasma or a control were administered to schoolchildren as a beverage (1.0 × 10¹¹ count LC-Plasma/day/person). The primary endpoint was to determine the efficacy of LC-Plasma in reducing the cumulative days absent from school due to upper respiratory disease (URID) and gastrointestinal disease (GID), and the secondary endpoint was to evaluate the potency of LC-Plasma on URID/GID symptoms and general well-being scores. LC-Plasma intake significantly reduced the cumulative days absent from school due to URID/GID (Odds ratio (OR) = 0.57, p = 0.004) and URID alone (OR = 0.56, p = 0.005); LC-Plasma also significantly reduced the number of cumulative fever positive days during the first 4 weeks of intervention (OR = 0.58, p = 0.001) and cumulative days with diarrhea during the last 4 weeks of the intervention period (OR = 0.78, p = 0.01). The number of positive general wellbeing days was significantly improved in the LC-Plasma group compared with the control throughout the intervention period (OR = 0.93, 0.93, p = 0.03, 0.04 in the first and last 4 weeks of the intervention, respectively). These data suggest that LC-Plasma seems to improve the health condition of elementary schoolchildren and reduces school absenteeism due to infectious disease, especially URID.     

失血合并闭合性骨折致小鼠脾脏树突状细胞抗原递呈功能下降

目的 研究失血合并闭合性骨折对小鼠脾脏树突状细胞（DC）抗原递呈功能的影响并初步探讨其机制。方法 致伤后24小时分离小鼠脾脏DC,检测脾脏DC在体外抗原作用下刺激脾非黏附细胞增殖的能力、细胞因子分泌功能及其表面重要分子表达的情况。结果 创伤小鼠脾脏DC体外刺激脾非黏附细胞增殖的能力下降,细胞因子分泌水平发生了变化,流式细胞分析结果显示其成熟度下降。结论 失血合并闭合性骨折可致小鼠脾脏DC的抗原递呈功能下降。     

Effects of metformin on recognition memory and hippocampal neuroplasticity in rats with metabolic syndrome

Metabolic syndrome (MS) is a health problem that is characterized by body fat accumulation, hypertension, dyslipidemia, and hyperglycemia; recently, it has been demonstrated that MS also damages memory processes. The first-line drug in the treatment of MS and type 2 diabetes mellitus is metformin, which is an antihyperglycemic agent. This drug has been shown to produce neuroprotection and to improve memory processes. However, the mechanism involved in this neuroprotection is unknown. A 90-day administration of metformin improved the cognitive processes of rats with MS as evaluated by the novel object recognition test, and this finding could be explained by an increase in the neuronal spine density and spine length. We also found that metformin increased the immunoreactivity of synaptophysin, sirtuin-1, AMP-activated protein kinase, and brain-derived neuronal factor, which are important plasticity markers. We conclude that metformin is an important therapeutic agent that increases neural plasticity and protects cognitive processes. The use of this drug is important in the minimization of the damage caused by MS.     

谷氨酸诱导的大鼠海马神经元兴奋毒性损伤中SNK/SPAR表达水平的变化

目的观察谷氨酸诱导的兴奋毒性损伤中血清诱导激酶(SNK)/树突棘相关的Rap特异性GTPase活化蛋白(SPAR)分子表达水平的变化。方法建立谷氨酸介导的大鼠海马神经元兴奋毒性损伤模型,RT-PCR方法检测SNK/SPARmRNA的表达;Western blot方法观察SNK/SPAR在蛋白质水平的表达;双重免疫荧光标记方法观察SNK/SPAR在神经元上的分布。结果100μmol/L谷氨酸刺激神经元10min后,1h内即可出现SNKmRNA表达水平升高,6h达高峰,随后逐渐下降,12h左右回到基线水平;3h可检测到SNK蛋白表达水平升高,36h达高峰,随后回降。SPAR表达水平的变化趋势与SNK相反。SNK与SPAR分布的变化主要体现在神经元的胞质和突起。结论SNK-SPAR途径可能参与了谷氨酸诱导的神经元兴奋毒性损伤过程。