LFA-1基因缺失对小鼠Nave T细胞体外向Th17细胞分化的影响

背景:淋巴细胞功能相关抗原-1(LFA-1)参与T细胞的活化和功能调节,与炎症性肠病的发病密切相关。目的:观察LFA-1基因缺失(LFA-1-/-)对小鼠Nave T细胞体外向Th17细胞分化的影响。方法:繁殖LFA-1-/-子代小鼠,提取鼠尾DNA,PCR法鉴定基因型。LFA-1-/-子代小鼠为实验组,野生型(WT)C57BL/6J小鼠为对照组,磁珠分选脾脏单个核细胞中的CD4+CD62L+Nave T细胞并检测其纯度。体外建立不同Th17细胞诱导分化体系[转化生长因子-β(TGF-β)、TGF-β+白细胞介素-6(IL-6)和TGF-β+IL-6+IL-23],以流式细胞术检测两组分选得到的Nave T细胞在不同体系中诱导出的Th17细胞比率,荧光定量PCR法和ELISA法检测Th17细胞特异性转录因子ROR-γt和特异性标记物IL-17A表达。结果:15只子代小鼠均为LFA-1-/-小鼠,磁珠分选得到的CD4+CD62L+Nave T细胞纯度大于95%。低剂量TGF-β+IL-6即能诱导出Th17细胞,在此基础上加入IL-23能促进更多Th17细胞产生。与WT对照组相比,LFA-1-/-组Nave T细胞在TGF-β+IL-6+IL-23体系中诱导产生Th17细胞的效应更为明显(17.2%±1.4%对5.7%±0.2%,P0.001),ROR-γt、IL-17A mRNA表达上调(P0.001),细胞培养上清液中IL-17A浓度升高(P0.01)。结论:LFA-1基因缺失能促进小鼠Nave T细胞体外向Th17细胞分化。     

KB-R7943对心力衰竭家兔哇巴因诱发心律失常的抑制作用

目的 探讨钠-钙交换体抑制剂KB-R7943对哇巴因诱发心衰家兔心律失常的影响.方法 40只成年家兔随机分为5组：假手术组、心衰对照组、哇巴因组、哇巴因合并KB-R7943（1μmol/L）组和哇巴因合并KB-R7943（5μmol/L）组.心衰组、哇巴因组、哇巴因合并KB-R7943（1 μmol/L）组和哇巴因合并K.B-R7943（5 μmol/L）组使用主动脉瓣关闭不全联合腹主动脉缩窄的方法建立心衰模型.建模8周后超声检测心功能,并利用Langendorff离体心脏灌流方法检测家兔各项离体心功能指标.灌流哇巴因（5μmol/L,4ml）诱发家兔心衰心脏产生心律失常,观察KB-R7943对离体心衰家兔心律失常的影响.结果 ①超声结果显示,与假手术组相比,心衰对照组家兔左室射血分数（LVEF）、短轴缩短率（％FS）均明显降低（P＜0.05）.②离体条件下,心衰对照组家兔离体心脏左室发展压（LVDP）、心率（HR）、室内压最大上升速率（＋dp/dtmax）、室内压最大下降速率（-dp/dtmax）较假手术组均明显下降（P＜0.05）.③哇巴因组1h内总心律失常（TT）、室速（VT）、室颤（VF）持续时间较心衰对照组明显增加（P＜0.05）.④与哇巴因组比较,哇巴因联合应用KB-R7943组1h内TT、VT、VF持续时间明显减短（P＜0.05）;与1 μmol/L KB-R7943相比,5μmol/L KB-R7943可使哇巴因诱发TT和VT时间进一步缩短（P＜0.05）.结论 钠-钙交换体抑制剂KB-R7943可抑制哇巴因诱发心衰家兔心律失常的持续时间,且较高浓度（5 μmol/L）KB-R7943对哇巴因诱发心衰家兔心律失常的抑制作用更强.     

Muscle phenotype in patients with myotonic dystrophy type 1

Introduction: The pathogenesis of muscle involvement in patients with myotonic dystrophy type 1 (DM1) is not well understood. In this study, we characterized the muscle phenotype in patients with confirmed DM1. Methods: In 38 patients, muscle strength was tested by hand‐held dynamometry. Myotonia was evaluated by a handgrip test and by analyzing the decrement of the compound muscle action potential. Muscle biopsies were assessed for morphological changes and Na⁺‐K⁺ pump content. Results: Muscle strength correlated with a decline in Na⁺‐K⁺ pump content (r = 0.60, P < 0.001) and with CTG expansion. CTG expansion did not correlate with severity of myotonia, proximal histopathological changes, or Na⁺‐K⁺ pump content. Histopathologically, we found few centrally placed nuclei (range 0.2–6.9%). Conclusions: The main findings of this study are that muscle weakness correlated inversely with CTG expansion and that central nuclei are not a prominent feature of proximal muscles in DM1. Muscle Nerve 47:409‐415, 2013     

Sodium and calcium mechanisms of rhythmic bursting in excitatory neural networks of the pre‐Bötzinger complex: a computational modelling study

The neural mechanisms generating rhythmic bursting activity in the mammalian brainstem, particularly in the pre‐Bötzinger complex (pre‐BötC), which is involved in respiratory rhythm generation, and in the spinal cord (e.g. locomotor rhythmic activity) that persist after blockade of synaptic inhibition remain poorly understood. Experimental studies in rodent medullary slices containing the pre‐BötC identified two mechanisms that could potentially contribute to the generation of rhythmic bursting: one based on the persistent Na⁺ current (I_NaP), and the other involving the voltage‐gated Ca²⁺ current (I_Ca) and the Ca²⁺‐activated nonspecific cation current (I_CAN), activated by intracellular Ca²⁺ accumulated from extracellular and intracellular sources. However, the involvement and relative roles of these mechanisms in rhythmic bursting are still under debate. In this theoretical/modelling study, we investigated Na⁺‐dependent and Ca²⁺‐dependent bursting generated in single cells and heterogeneous populations of synaptically interconnected excitatory neurons with I_NaP and I_Ca randomly distributed within populations. We analysed the possible roles of network connections, ionotropic and metabotropic synaptic mechanisms, intracellular Ca²⁺ release, and the Na⁺/K⁺ pump in rhythmic bursting generated under different conditions. We show that a heterogeneous population of excitatory neurons can operate in different oscillatory regimes with bursting dependent on I_NaP and/or I_CAN, or independent of both. We demonstrate that the operating bursting mechanism may depend on neuronal excitation, synaptic interactions within the network, and the relative expression of particular ionic currents. The existence of multiple oscillatory regimes and their state dependence demonstrated in our models may explain different rhythmic activities observed in the pre‐BötC and other brainstem/spinal cord circuits under different experimental conditions.     

Sodium thiosulfate attenuates high phosphorous induced vascular calcification in rats with 5/6 nephrectomy

Objective To observe the expression of Klotho and Na+/Pi cotransporter in high phosphorous-induced rats with 5/6 nephrectomy and its relationship with vascular calcification, as well as to investigate the effect of early intervention by sodium thiosulfate (STS) on the progression of vascular calcification. Methods Either 5/6 nephrectomy (n=21) or sham operation (n=14) was conducted on 35 Sprague Dawley rats, who were then fed with high phosphorus (HP) diet or normal phosphorus (NP) diet for 16 weeks respectively. The rats were divided into 5 groups as follows: (1) remnant kidney rats receiving HP diet (NHP, n=7), (2) remnant kidney rats receiving NP diet (NNP, n=7), (3) sham operation rats receiving NP diet (SNP, n=7), (4) sham operation rats receiving HP diet (SHP, n=7), (5) remnant kidney rats receiving HP diet with STS (THP, n=7). The treatment group was given STS intraperitoneally three times a week for 16 weeks. At the end of the 16th week, rats tail artery blood pressures were tested, serum creatinine (Scr), calcium (Ca2+), phosphorus (P3+), FGF23, iPTH and urine protein were examined. Throacic aorta and kidney were then removed. Vascular calcification was confirmed by Von kossa staining. Klotho and Pit-1 expression in aortas were determined by immunohistochemistry. Renal lesion was determined by PASM-Masson staining. Renal Klotho and NaPi-2a mRNA were determined by real time RT-PCR. Results After 16 weeks, Scr, P3+, FGF23, iPTH, uric protein and blood pressure were significantly higher in NHP than those in SNP rats (all P＜0.05). PASM-Masson staining revealed typical renal pathology of chronic renal failure in NHP group. With the treatment of STS, THP rats showed significant decrease in Scr, P3+, FGF23, iPTH, uric protein and blood pressure by comparison with NHP group (all P＜0.05). Significant vascular calcification was found in NHP group while NNP and SHP group occasionally had vascular calcification; THP group had marked alleviation of vascular calcification. The aorta and renal expression of Klotho decreased remarkably while expression of Pit-1 and NaPi-2a increased significantly in NHP compared with SNP group (all P＜0.05). Accordingly, the aorta and renal expression of Klotho increased and Pit-1 and NaPi-2a decreased significantly in THP compared with NHP group (P＜0.05). Conclusions The early intervention of sodium thiosulfate might regulate Klotho and Na+/Pi cotransporter expression in both aorth and kidney, decreasing serum phosphate, delaying progression of vascular calcification and improving renal function.     

定心汤对心律失常大鼠模型的影响

目的  研究定心汤对心律失常大鼠模型的作用及各项相关指标的影响。方法  采用乌头碱所致心律失常模型观察药物作用。结果  定心汤对乌头碱致大鼠室性心律失常模型有明显作用,缩短心律失常持续时间,降低血清丙二醛（MDA）含量,增加血清超氧化物歧化酶（SOD）活性,增加心肌组织中Na+-K+-ATP酶、Ca2+-ATP酶活性。结论  定心汤有明显的抗室性心律失常作用,且呈剂量依赖性。

     

Activation of voltage‐gated sodium current and inhibition of erg‐mediated potassium current caused by telmisartan,an antagonist of angiotensin II type‐1 receptor,in HL‐1 atrial cardiomyocytes

Telmisartan (TEL) is a non‐peptide blocker of angiotensin II type‐1 (AT₁) receptor. However, the mechanisms through which this drug interacts directly with ion currents in hearts remain largely unclear. Herein, we aim to investigate the effects of TEL the on ionic currents and membrane potential of murine HL‐1 cardiomyocytes. In whole‐cell recordings, addition of TEL stimulated the peak and late components of voltage‐gated Na⁺ currents (I_Na) with different potencies. The EC₅₀ values required to achieve the stimulatory effect of this drug on peak and late I_Na were 0.2 and 1.2 μmol/L, respectively, and the current‐voltage relationship of peak I_Na shifted toward less‐depolarized potentials during exposure to TEL. Telmisartan not only increased peak I_Na but also prolonged the inactivation time course of late I_Na. Amiodarone (Amio) or ranolazine (Ran), but not angiotensin II, could reverse TEL‐mediated effects. The drug enhanced the recovery rate of I_Na inactivation and exerted an inhibitory effect on erg‐mediated K⁺ and L‐type Ca²⁺ currents. In whole‐cell current‐clamp recordings, addition of the drug resulted in prolongation of the duration of action potentials (APs) in a dose‐dependent manner in HL‐1 cells; Amio or Ran could reverse this increase in AP durations. Telmisartan‐mediated prolongation of AP was attenuated in KCNH2 siRNA‐transfected HL‐1 cells. In cultured smooth muscle cells of the human coronary artery, TEL enhanced I_Na amplitudes and slowed current inactivation. Stimulation by TEL of I_Na in HL‐1 cells did not simply increase current magnitude but altered current kinetics, thereby suggesting state‐dependent activation. Telmisartan may have greater affinity to the open/inactivated state than to the resting state residing in Na_V channels. Collectively, TEL‐mediated stimulation of I_Na and inhibition of I_K(erg) could be an important ionic mechanism underlying the increased cell excitability of HL‐1 cells; these actions, however, cannot be entirely explained by its blockade of AT₁ receptor.