An enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies to different parts of the gram-negative lipopolysaccharide core region

Bovine serum albumin was complexed with the core antigens of either Escherichia coli J5 LPS, Salmonella minnesota R595 LPS or E. coli lipid A. These core-BSA complexes were used for solid-phase coating in ELISAs for anti-core antibodies. Antibodies, binding to various parts of the core region were easily quantified in a single experimental set-up, which was hitherto not possible. The ELISA has only 3 incubation steps and is not costly as only moderate amounts of the core antigens (i.e., 1 microgram per test) were needed for coating. The sensitivity proved to be excellent and the complexes were biologically fully active (compared to native, smooth LPS), which make them suitable for the screening (after fusion) of monoclonal anti-core antibodies. Another possible application is the large-scale screening of blood-bank sera in order to find samples with a high anti-core antibody content.     

Biochemical characterization of I-Ak proteins from mutant antigen-presenting B-cell--B-lymphoma hybridomas

Chemically induced mutants of an I-Ak,d expressing antigen-presenting B-cell--B-lymphoma hybridoma have recently been generated by immunoselection in vitro and were found to possess alterations in some of their serologically and functionally defined I-Ak region dependent functions. In order to identify at the structural level the origin of the differences in serological and functional properties of these mutants, I-Ak molecules from several of these mutant hybridomas were compared biochemically to wild-type I-Ak polypeptides by two-dimensional gel electrophoresis and high-pressure liquid chromatographic tryptic peptide analyses. Two-dimensional gel electrophoresis indicated that no major structural alterations, resulting in changes in mol. wt or charge, had occurred in the Ak alpha or Ak beta polypeptides from the mutant cells. Likewise, Ak alpha peptide maps of the mutants were indistinguishable from the normal Ak alpha peptide maps. However, two of the three mutants studied did exhibit one additional peptide in their Ak beta peptide maps. These results suggest that the major deficiencies in T-cell-activating functions of these mutants are a result of a limited alteration in the Ak beta polypeptide primary structure.     

Effects of veratridine, tetrodotoxin and other drugs that alter electrical behaviour on secretion of melanocyte-stimulating hormone from melanotrophs of the pituitary pars intermedia

Since melanotrophs are electrically active and exhibit spontaneous Na spikes, a study was made of the effects, on melanotroph secretion, of drugs known to influence electrical properties. The output of melanocyte-stimulating hormone was measured from perifused neurointermediate lobes of mice or melanotrophs dispersed from such lobes of mice or rats. Veratridine (200 microM), which is known to increase Na permeability in a variety of cells, caused a large, although transient, increase in secretion from the melanotrophs that required extracellular Ca2+ and was blocked by the Na-channel blocker tetrodotoxin (1 microM). Tetraethylammonium (10 mM), which blocks K channels and thus prolongs the duration of the action potential in many cells, also stimulated secretion in the melanotrophs in a Ca-dependent manner. This response was not, however, blocked by tetrodotoxin, and is thus not attributable to prolongation of Na spikes in these cells. Moreover, tetrodotoxin did not inhibit basal secretion. The stimulant effect of veratridine on secretion in melanotrophs and its suppression by tetrodotoxin suggests that voltage-dependent Na channels can participate in the regulation of hormone output in these cells of the pituitary pars intermedia. However, the apparent lack of effect of tetrodotoxin on basal secretion suggests that the spontaneous Na spikes previously observed in these cells are not required for promoting the Ca influx which other evidence shows is important for basal secretion.     

Membrane properties of rat locus coeruleus neurones

Intracellular recordings were made from neurones in the locus coeruleus contained within a slice cut from rat pons and maintained in vitro. Most neurones fired action potentials spontaneously at frequencies of between 1 and 5 Hz; this did not arise from spontaneous synaptic input but appeared to result from endogenous properties of the membrane conductances. Under voltage clamp at potentials near threshold for action potential generation (? 55 mV) there was a persistent inward calcium current. This current became less with membrane hyperpolarization and was abolished at about ?70 mV. Two potassium currents were observed. The first had properties similar to that generally described as the “fast” potassium current (I_K,A); it flowed transiently (for about 200 ms) when the membrane potential passed from about ?65 to ?45 mV, and was blocked by 4-aminopyridine. The second was a calcium-activated potassium current (I_K,Ca); it flowed for several seconds following a burst of calcium action potentials. Spontaneous and evoked action potentials had both tetrodotoxin-sensitive and tetrodotoxin-resistant components. The latter was apparently due to calcium entry. The potential changes occurring during the spontaneous firing of locus coeruleus neurones could be reconstructed qualitatively from the ionic conductances observed. The membrane properties of the locus coeruleus neurones were remarkably uniform; however, about 5% of cells impaled within the region of the locus coeruleus were electrophysiologically distinct. These atypical cells had short duration action potentials, did not fire spontaneously and had large spontaneous depolarizing synaptic potentials.     

Electrical behaviour in a line of anterior pituitary cells (GH cells) and the influence of the hypothalamic peptide, thyrotrophin releasing factor

Anterior pituitary cells of the GH line, which secrete prolactin spontaneously, showed spontaneous action potential activity. Thyrotrophin releasing factor, which increases secretion in these cells, caused a prompt increase of action potential frequency. Potassium, another secretagogue, depolarized the cells and sometimes initiated a burst of action potentials at the onset of this effect. The action potentials persisted in tetrodotoxin-containing and Na-free media, but were suppressed by the Ca-channel blocker, methoxyverapamil. Moreover, elevating the extracellular Ca²⁺ concentration increased the amplitude of the action potentials. These action potentials therefore have a prominent Ca component. This endows them with a particular interest since secretory activity of these cells is known to be dependent on extracellular Ca²⁺. Ba²⁺, which can substitute for Ca²⁺ in maintaining secretion, also substituted for Ca²⁺ in the maintenance of the action potentials. In addition, Ba²⁺ prolonged action potentials remarkably: tetraethylammonium was less effective in this regard.The several parallels between known secretory behaviour and electrical phenomena encourage the view that analysis of electrical activity in anterior pituitary cells may provide useful clues to events involved in stimulus-secretion coupling and in the secretory control exerted by the brain.     

Release of endogenous 5-hydroxytryptamine from the neural and the intermediate lobe of the rat pituitary gland evoked by electrical stimulation of the pituitary stalk

A calcium-dependent release of 5-hydroxytryptamine from the neural and intermediate lobe of the rat pituitary gland has been demonstrated following electrical stimulation of the pituitary stalk with stimulation parameters thought to evoke propagated action potentials. The 5-hydroxytryptamine release from the intermediate lobe was double that from the neural lobe. The mass of the intermediate lobe of the rat is about 80% of that of the neural lobe [Holzbauer, Racké, Mann, Cooper, Cohen, Krause and Sharman (1984) J. Neural Transm. 59, 91-104]. The relatively high overflow of 5-hydroxytryptamine from the intermediate lobe agrees with immunohistochemical studies in which a larger number of 5-hydroxytryptamine fibres were seen in the intermediate lobe than in the neural lobe. The present results have demonstrated that the rat hypophysis contains neuronal 5-hydroxytryptamine. They also suggest that this amine may act as a neurotransmitter substance in the neural and intermediate lobe.     

LncRNA-MALAT1通过miR-142-3p/TEAD1分子轴调控结直肠癌细胞增殖与凋亡#br#

目的　探讨长链非编码RNA-肺腺癌转移相关转录子1（LncRNA-MALAT1）对结直肠癌细胞增殖与凋亡的影响及相关作用机制。方法　通过Real-time PCR与Western blot实验检测结直肠癌细胞株与人正常结肠上皮细胞中LncRNA-MALAT1、miR-142-3p基因以及TEA结构域转录因子1（TEAD1）蛋白的表达;使用si-MALAT1转染HCT116细胞,在此基础上共转染miR-142-3p inhibitor,利用Real-time PCR与Western blot检测细胞中LncRNA-MALAT1与miR-142-3p基因以及TEAD1、Bax、Bcl-2与Cyclin D1蛋白的表达,通过CCK-8实验检测细胞的增殖水平,通过流式细胞术检测细胞的凋亡水平,通过双荧光素酶实验检测LncRNA-MALAT1与miR-142-3p以及miR-142-3p与TEAD1的结合。结果　与人正常结肠上皮细胞相比,结直肠癌细胞株中LncRNA-MALAT1基因与TEAD1蛋白呈高表达,miR-142-3p基因呈低表达（P＜0.05）;沉默LncRNA-MALAT1能够促进miR-142-3p基因与Bax蛋白表达,抑制LncRNA-MALAT1基因以及Bcl-2、Cyclin D1与TEAD1蛋白表达,抑制细胞增殖,并促进细胞凋亡;在此基础上沉默miR-142-3p能够对上述调控作用实现部分逆转;双荧光素酶实验结果显示,LncRNA-MALAT1与miR-142-3p以及miR-142-3p与TEAD1能够结合。结论　LncRNA-MALAT1能够结合miR-142-3p,促进miR-142-3p靶基因TEAD1表达,进而促进结直肠癌细胞增殖,抑制其细胞凋亡,促进结直肠癌的病理进程。     

钾通道阻滞剂对人肺腺癌细胞增殖和凋亡的影响

目的研究电压依赖性延迟整流钾通道阻断剂4-氨基吡啶(4-aminopyridine,4-AP)、钙离子激活钾通道阻断剂四乙铵(tetraethylammonia,TEA)对人肺腺癌细胞(AGZY-83-a)的影响,并探讨人肺腺癌细胞株凋亡的机制.方法体外细胞培养法培养人肺腺癌细胞株,采用MTT法检测不同浓度4-AP、TEA对细胞增殖的影响.透射电镜、流式细胞术(FCM)检测细胞凋亡情况.比色法检测细胞内Caspase-3活性改变.结果不同浓度的4-AP、TEA作用于细胞48h后,与对照组相比各组吸光度值(A490)均明显降低(n=10,P＜0.001),并且呈浓度依赖关系.4-AP、TEA组的IC50为3.59mmol/L和3.97mmol/L.4-AP及高浓度的TEA使人肺腺癌细胞株细胞凋亡率增加.经4-AP、TEA处理48h的AGZY-83-a细胞内Caspase-3的A405较正常对照组有显著增加(n=6,P＜0.001).结论钾通道阻滞剂4-AP、TEA对AGZY-83-a细胞增殖有明显的抑制作用,抑制率与药物浓度正相关.诱导人AGZY-83-a细胞凋亡,4-AP和TEA诱导AGZY-83-a细胞凋亡的过程中细胞内Caspase-3活性增加.     

银杏内酯B对大鼠下丘脑室旁核神经元自发放电的影响

目的研究银杏内酯B（GinkgolideB，BN52021）对静息状态下的下丘脑脑片室旁核神经元自发放电活动的影响。方法应用细胞外记录单位放电技术。结果（1）在27个下丘脑室旁核神经元放电单位给予银杏内酯B（0．1，1，10μmol／L）2分钟，有26个放电单位（96．30％）放电频率明显降低，且呈剂量依赖性；（2）预先用0．2mmol／L的L—glutamate（L-Glu）灌流下丘脑脑片，8个放电单位放电频率明显增加，表现为癫痫样放电，在此基础上灌流银杏内酯B（1μmol／L）2分钟，其癫痫样放电全部被抑制；（3）预先用L型钙通道开放剂BayK8644灌流8个下丘脑脑片，8个放电单位（100％）全部放电增加，在此基础上灌流银杏内酯B（1μmol／L）2分钟，8个放电单位（100％1放电频率明显减低（4）在8个下丘脑室旁核神经元放电单位上，银杏内酯B（1μmol／L）的抑制效应可被广泛钾通道阻断剂（tetraethylammonium，TEA）1mmol／L完全阻断。结论银杏内酯B（GinkgolideB，BN520211可抑制下丘脑室旁核神经元自发放电，并可抑制由L—glutamate诱发的神经元放电。提示银杏内酯B对心血管中枢神经元通过降低其活动而具有一定程度的保护作用，这种作用可能与银杏内酯B抑制L型钙通道有关，而且可能与延迟整流型钾通道（delayed rectifier potassium channel，KDR）有关。     

Characterization of the mechanism underlying stonustoxin-mediated relaxant response in the rat aorta in vitro

Stonustoxin (SNTX) is a lethal factor isolated from the venom of the stonefish Synanceja horrida. Although SNTX exhibits a multitude of biological activities, the primary cause of death upon administration of the toxin is attributed to marked hypotension. We investigated the possible mechanisms underlying the vascular hyporeactivity of this novel toxin. Cumulative doses of SNTX (5-320 ng/mL) induced concentration-dependent relaxation in phenylephrine (PE)--precontracted rat aortic rings with intact endothelium. Endothelium removal abolished the relaxation induced by SNTX. Tetraethylammonium (TEA), an inhibitor of K(+) channels, partially inhibited SNTX-induced relaxation. Similarly, SNTX-induced relaxation was partially attenuated by the SP receptor antagonist (NATB), whereas the inducible iNOS inhibitor, AMT-HCl, completely abolished the relaxation caused by SNTX. From the results obtained, it can be postulated that a component of SNTX-mediated vasorelaxation is via binding of either SNTX or SP to the SP receptors that are located on the endothelial cells. Occupation of these SP receptors causes subsequent production of NO and activation of K(+) channels, thus leading to vasorelaxation of the rat aortic rings.