Cyclic GMP modulates store-operated calcium entry inducing phosphatidylserine translocation at the surface of megakaryocytic cells

When subjected to stimulation, cells from the vascular compartment show a spontaneous collapse of the plasma membrane phospholipid asymmetry and phosphatidylserine is exposed at the external leaflet. Thus, phosphatidylserine externalization is essential for normal hemostasis and phagocytosis. The mechanism governing the migration of phosphatidylserine to the exoplasmic leaflet is not yet fully understood. We have proposed that store-operated calcium entry (SOCE) constitutes a key step of this process. Here, interaction of [Ca(2+)](i), cAMP and cGMP pathways and phosphatidylserine exposure was examined in human megakaryocytic cells. The membrane permeable cAMP and cGMP analogues, pCPT-cAMP and pCPT-cGMP, enhanced the Ca(2+) signal induced by ionophore and SOCE. Responses to pCPT-cAMP and pCPT-cGMP were independent of protein kinase A, protein kinase G (PKG) or ERK pathways. Inhibition of small G-proteins reduced or abolished the increase of [Ca(2+)](i) induced by pCPT-cAMP or pCPT-cGMP, respectively. pCPT-cGMP but not pCPT-cAMP enhanced the ability of cells to expose phosphatidylserine. This effect was not prevented by the inhibition of PKG or small G-proteins. These results show the differential role of cyclic nucleotides in the Ca(2+)-dependent membrane remodeling. Hence, pCPT-cGMP is another regulatory element for the completion of SOCE-induced phosphatidylserine transmembrane redistribution in HEL cells through a mechanism implicating small G-proteins.     

一种用于自由活动动物的微型多模式遥控刺激器

本文采用集成有射频功能的片上系统(nRF24E1),研制了一种用于自由活动小动物的微型多模式遥控刺激器。刺激参数的设置及结果分析均由10 m外的个人计算机进行。通过离体实验,即刺激蛙坐骨神经干时产生动作电位并可观察到伪迹;及在体大鼠的训练操作性条件反射的行为学实验,即在Y臂迷宫中训练大鼠听到不同声音完成左右运动,如果完成正确给予前脑内侧束以电刺激,我们观察到5 d内大鼠的正确率增加3倍,达到93．5％。上述实验都验证了该刺激器的有效性与稳定性。本系统具有体积小(18 mm×28 mm双层线路板)、重量轻(不含电池5 g)、简单、实用、可靠等特点,能有效地用于自由活动小动物的实验研究。为基于电刺激的小动物行为训练(动物机器人)及相关神经生理学实验研究,提供了新的实验条件和实验手段。     

Transcranial magnetic stimulation attenuates cell loss and oxidative damage in the striatum induced in the 3-nitropropionic model of Huntington's disease

An investigation was conducted on the effect of transcranial magnetic field stimulation (TMS) on the free radical production and neuronal cell loss produced by 3-nitropropionic acid in rats. The effects of 3-nitropropionic acid were evaluated by examining the following changes in: the quantity of hydroperoxides and total radical-trapping antioxidant potential (TRAP), lipid peroxidation products, protein carbonyl groups, reduced glutathione (GSH) content, glutathione peroxidase (GSH-Px), catalase and succinate dehydrogenase (SDH) activities; total nitrite and cell death [morphological changes, quantification of neuronal loss and lactate dehydrogenase (LDH) levels]. Our results reveal that 3-nitropropionic acid induces oxidative and nitrosative stress in the striatum, prompts cell loss and also shows that TMS prevents the harmful effects induced by the acid. In conclusion, the results show the ability of TMS to modify neuronal response to 3-nitropropionic acid.     

DNA binding mode transitions of Escherichia coli HU(alphabeta): evidence for formation of a bent DNA--protein complex on intact, linear duplex DNA

Escherichia coli HU_αβ, a major nucleoid-associated protein, organizes chromosomal DNA and facilitates numerous DNA transactions. Using isothermal titration calorimetry, fluorescence resonance energy transfer and a series of DNA lengths (8 bp, 15 bp, 34 bp, 38 bp and 160 bp) we established that HU_αβ interacts with duplex DNA using three different nonspecific binding modes. Both the HU to DNA molar ratio ([HU]/[DNA]) and DNA length dictate the dominant HU binding mode. On sufficiently long DNA (≥ 34 bp), at low [HU]/[DNA], HU populates a noncooperative 34 bp binding mode with a binding constant of 2.1 ± 0.4 × 10⁶ M^− 1, and a binding enthalpy of + 7.7 ± 0.6 kcal/mol at 15 °C and 0.15 M Na⁺. With increasing [HU]/[DNA], HU bound in the noncooperative 34 bp mode progressively converts to two cooperative (ω∼20) modes with site sizes of 10 bp and 6 bp. These latter modes exhibit smaller binding constants (1.1 ± 0.2 × 10⁵ M^− 1 for the 10 bp mode, 3.5 ± 1.4 × 10⁴ M^− 1 for the 6 bp mode) and binding enthalpies (4.2 ± 0.3 kcal/mol for the 10 bp mode, − 1.6 ± 0.3 kcal/mol for the 6 bp mode). As DNA length increases to 34 bp or more at low [HU]/[DNA], the small modes are replaced by the 34 bp binding mode. Fluorescence resonance energy transfer data demonstrate that the 34 bp mode bends DNA by 143 ± 6° whereas the 6 bp and 10 bp modes do not. The model proposed in this study provides a novel quantitative and comprehensive framework for reconciling previous structural and solution studies of HU, including single molecule (force extension measurement), fluorescence, and electrophoretic gel mobility-shift assays. In particular, it explains how HU condenses or extends DNA depending on the relative concentrations of HU and DNA.     

Successful catheter ablation of persistent electrical storm late post myocardial infarction by targeting purkinje arborization triggers

Drug refractory ventricular tachycardia (VT) occurring as a storm after acute myocardial infarction has grave prognosis. We report a case of a middle-aged lady who presented with drug refractory VT that lead to persistent electrical storm two weeks after an anterior wall myocardial infarction. She underwent a successful catheter ablation of VT followed a few days later by implantation of an AICD. Catheter ablation of the VT could control the persistent electrical storm and the patient was free from a recurrence of VT at three month follow up.     

Sit down and stay here! Transport response elicitation modulates subsequent activity in rat pups

Investigators tested the notion that simulating a mother rat's transporting of her pup to a novel environment would result in a reduction in subsequent activity in that infant. Fourteen-day-old rats were tested for activity levels, rearing and turning in an open-field after having undergone one of the three conditions: transport response elicitation; passive handling; or minimal contact. Elicitation of the transport response resulted in reductions in each of these behaviors. These results are discussed with respect to the adaptive significance of reducing behavioral activity after elicitation of the transport response.     

局部力学刺激对黄瓜系统抗病性的诱导

病原真菌在侵入植物细胞过程中,除了分泌化学物质外还通过物理挤压细胞产生力学作用.用压应力作为力学信号,研究了局部力学刺激对黄瓜系统抗病性的诱导.结果表明,力学刺激可以诱导黄瓜系统抗病性的产生.当细胞壁与质膜间的黏附被Arg-Gly-Asp(RGD)阻断后,力学刺激对黄瓜系统抗病性的诱导几乎完全被减除.通过薄层色谱和液相色谱分析,发现力学刺激可以使植保素含量明显增加.这表明黄瓜植保素的积累可能是力学刺激诱导其产生抗性的原因之一.而细胞壁与质膜间的黏附被RGD阻断后,力学刺激只能诱导植保素的部分积累.即力学刺激对植保素积累的诱导依赖于细胞膜与细胞壁间的黏附.     

Dynamic Processing of Nociception in Cortical Network in Conscious Rats: A Laser-evoked Field Potential Study

(1) Field potential study in conscious rats provides a convenient and effective animal model for pain mechanism and pharmacological research. However, the spatial-temporal character of nociception processing in cortex revealed by field potential technique in conscious rats remains unclear. (2) In the present study, multi-channel field potentials evoked by noxious laser stimulation applied to the hind paw of conscious rats were recorded through 12 chronically implanted skull electrodes. Independent component analysis (ICA) was used to remove possible artifacts and to extract the specific nociception-related component. (3) Two fast sharp responses and one slow blunt response were evoked by noxious laser stimulation. Systemic morphine (5 mg/kg, i.p.) preferentially attenuated the amplitude of the slow blunt response while had no significant effect on the first two sharp responses. ICA revealed that those responses came from activities of contralateral anterior parietal area, medial frontal area and posterior parietal area. A movement artifact was also detected in this study. Partial directed coherence (PDC) analysis showed that there were changes of information flows from medial frontal and posterior parietal area to anterior parietal area after noxious laser stimulation. (4) Characterization of the spatio-temporal responses to noxious laser stimulation may be a valuable model for the study of pain mechanisms and for the assessment of analgesia.