骨形态发生蛋白2及碱性成纤维生长因子2对大鼠骨髓间充质干细胞膜片增殖和成骨分化的影响

文题释义： 细胞膜片技术：是在体外接种培养高密度的细胞，使其相互融合生长至100%而形成的透明致密膜状物。该技术不需要胰酶消化即可收集细胞，因此保留了大量的胞外基质、细胞间连接以及细胞-基质连接等结构。目前细胞膜片技术已成为组织工程领域的研究热点，已被推广应用于牙周膜、角膜、心脏、软骨、食管等多种组织器官修复。 成骨细胞：主要由内外骨膜和间充质始祖细胞分化而来，在复杂的骨形成过程中发挥着主要的功能，承担着骨基质的合成、分泌和矿化。骨髓间充质干细胞具有多向分化潜能，能定向分化为成骨细胞，其成骨分化过程可受多种因素的影响，如细胞因子的调控、遗传因素和激素水平等。背景：现阶段骨形态发生蛋白2和碱性成纤维生长因子2对骨髓间充质干细胞膜片增殖、成骨分化的影响和作用机制还尚未可知，如何将生长因子与组织工程细胞膜片技术相整合，最终将其用于骨缺损修复具有重要意义。 目的：探讨单独及联合应用骨形态发生蛋白2和碱性成纤维生长因子2对骨髓间充质干细胞膜片增殖和成骨分化的影响。 方法：体外分离培养鉴定SD大鼠骨髓间充质干细胞并构建细胞膜片，选用不同质量浓度的骨形态发生蛋白2和碱性成纤维生长因子2单独及联合诱导骨髓间充质干细胞膜片，CCK-8法结合碱性磷酸酶活性检测确定2种因子促进膜片增殖和成骨分化的最佳有效质量浓度；然后对骨髓间充质干细胞膜片进行成骨诱导，通过大体及显微镜观察、Vonkossa染色、茜素红染色、RT-PCR检测相关成骨标志物来评估诱导效果。 结果与结论：单独应用骨形态发生蛋白2可增强骨髓间充质干细胞膜片的碱性磷酸酶活性，最佳质量浓度为100 μg/L(P < 0.001)，单独应用碱性成纤维生长因子2能加速骨髓间充质干细胞膜片的增殖，最佳质量浓度为20 μg/L(P < 0.001)，而联合应用既可以促进膜片增殖又能提高其碱性磷酸酶活性(P < 0.001)；经成骨诱导后，4组膜片在形态学上无明显差异，均能诱导骨髓间充质干细胞膜片的成骨分化，其中联合组钙结节最明显(P < 0.001)，可显著促进膜片晚期成骨分化并抑制其早期成骨分化，具有明显的协同促进作用(P < 0.001)。结果表明，骨形态发生蛋白2和碱性成纤维生长因子2联合应用时具有协同作用，既可以促进骨髓间充质干细胞膜片增殖，又能显著增强其成骨诱导能力。ORCID: 0000-0003-1918-579X(何惠宇) 中国组织工程研究杂志出版内容重点：干细胞；骨髓干细胞；造血干细胞；脂肪干细胞；肿瘤干细胞；胚胎干细胞；脐带脐血干细胞；干细胞诱导；干细胞分化；组织工程     

氯胺酮对离体大鼠心室肌细胞瞬时外向钾电流的影响

目的研究氯胺酮对大鼠心室肌细胞瞬时外向钾电流(Ito)的影响。方法酶解法分离大鼠心室肌细胞,采用全细胞膜片钳技术记录Ito,观察50μmol/L氯胺酮对Ito电流-电压曲线以及不同浓度氯胺酮对Ito的影响,并研究氯胺酮对Ito通道动力学的影响。结果钳制电压-40mV,刺激电压 70mV条件下,临床相关浓度的氯胺酮50μmol/L使Ito的电流峰值降低23·4%(P<0·01),冲洗后,Ito能够完全恢复。5、10、50、100、500、1000、5000μmol/L的氯胺酮抑制Ito呈浓度依赖性,电流抑制率分别为(13·8±9·7)%、(17·5±6·7)%、(23·4±8·8)%、(31·5±6·7)%、(63·3±5·5)%、(79·7±2·7)%、(88·9±4·4)%,其半数有效浓度(IC50)为299μmol/L。100μmol/L的氯胺酮对激活曲线没有影响;使Ito的失活曲线明显右移,半数失活电压(V1/2)在给药前后数值分别为(-28·27±0·20)mV和(-25·34±0·27)mV(P<0·01),斜率因子(k)值分别为(3·23±0·46)mV和(3·40±0·55)mV(P>0·05)。结论氯胺酮可明显阻滞大鼠心室肌的Ito,这是氯胺酮延长大鼠心室肌动作电位的机理之一,同时氯胺酮使Ito的失活曲线右移。     

非右房肥大的P波高电压(附39例临床分析)

本文报告39例临床上除外右房肥大的P波高电压,此种P波高电压主要见于冠心病及急性颅脑疾患,二者之和占76.9%。其形态64%与肺性P波相同。产生的机制可能与结间束传导阻滞、中枢调节机能受累、交感神经兴奋性增高等有关。     

Comparison of glycaemic control over 1 year with pioglitazone or gliclazide in patients with Type 2 diabetes.

AIMS: To compare long-term (1 year) efficacy and safety of pioglitazone and gliclazide in patients with Type 2 diabetes. METHODS: This was a double-blind, multicentre, comparative, parallel group trial in 283 patients with Type 2 diabetes, who were randomized to receive 1-year treatment with pioglitazone 30-45 mg/day or gliclazide 80-320 mg/day. Drug dose was titrated on the basis of self-monitored blood glucose (SMBG) measurements and HbA1c values. The 1-year changes in HbA1c, fasting blood glucose (FBG), insulin, HOMA-S (HOmeostatic Model Assessment) and SMBG were compared. In a subgroup of patients (n = 10), systemic glucose production and utilization were determined by a combination of isotopic (deuterated glucose) and clamp techniques. RESULTS: In both groups, there were similar decreases in HbA1c (pioglitazone: -0.79%; gliclazide: -0.79%) and FBG (pioglitazone: -1.0 mmol/l; gliclazide: -0.7 mmol/l), whereas the slope of the reduction of fasting blood glucose was different between groups (P = 0.004). Insulin levels as well as insulin resistance assessed using HOMA-S decreased significantly only after pioglitazone treatment (-11.94 pmol/l and -1.03, respectively, both P = 0.002 vs. baseline). A significantly greater reduction in systemic glucose production was observed in the pioglitazone group (-2.48 micromol/kg/min, P = 0.042) than in the gliclazide group (-1.02 micromol/kg/min). A few, mild adverse events occurred in both groups. CONCLUSIONS: A comparable decrease in HbA1c and FBG was observed with pioglitazone and gliclazide. However, with pioglitazone there was a continuous decrease in FBG over 1 year, whereas gliclazide failed to maintain a similar trend. This favourable effect of pioglitazone was due to its insulin-sensitizing effect and ability to decrease systemic glucose production.     

Pharmacological properties of Ca2+-activated K+ currents of ramified murine brain macrophages

Using the whole-cell configuration of the patch clamp technique, calcium-activated potassium currents (I_K,Ca) were investigated in ramified murine brain macrophages. In order to induce I_K,Ca the intracellular concentration of nominal free Ca²⁺ was adjusted to 1μM. The Ca²⁺-activated K⁺ current of brain macrophages did not show any voltage dependence at test potentials between –120 and +30mV. A tenfold change in extracellular K⁺ concentration shifted the reversal potential of I_K,Ca by 51mV. The bee venom toxin apamin applied at concentrations of up to 1μM did not affect I_K,Ca. Ca²⁺-activated K⁺ currents of ramified brain macrophages were highly sensitive to extracellularly applied charybdotoxin (CTX). The half-maximal effective concentration of CTX was calculated to be 4.3nM. In contrast to CTX, the scorpion toxin kaliotoxin did not inhibit I_K,Ca at concentrations between 1 and 50nM. Tetraethylammonium (TEA) blocked 8.0% of I_K,Ca at a concentration of 1mM, whereas 31.4% of current was blocked by 10mM TEA. Several inorganic polyvalent cations were tested at a concentration of 2mM for their ability to block I_K,Ca. La³⁺ reduced I_K,Ca by 72.8%, whereas Cd²⁺ decreased I_K,Ca by 17.4%; in contrast, Ni²⁺ did not have any effect on I_K,Ca. Ba²⁺ applied at a concentration of 1mM reduced I_K,Ca voltage-dependently at hyperpolarizing potentials. Received: 17 January / Accepted: 5 May 1997     

The effects of changes to action potential duration on the calcium content of the sarcoplasmic reticulum in isolated guinea-pig ventricular myocytes

. We have estimated sarcoplasmic reticulum calcium content using rapid application of caffeine on voltage clamped, isolated guinea-pig ventricular myocytes. Caffeine induces the release of calcium from the sarcoplasmic reticulum and this calcium is extruded from the cells by the sarcolemmal Na/Ca exchange. Integrating the inward Na/Ca exchange current thus allows estimations of sarcoplasmic reticulum calcium content. Ventricular myocytes were stimulated to reach new steady-states by action potential voltage clamps of varying duration. Once contractile steady-state had been reached caffeine was rapidly applied in place of the next action potential and sarcoplasmic reticulum calcium content measured. Prolonging the action potential duration increased sarcoplasmic reticulum calcium content and vice-versa. This calcium loading may underlie the positive inotropic effect of increased action potential duration. Received: 11 July 1996 / Received after revision: 15 October 1996 / Accepted: 26 November 1996     

Electrophysiological Characterization of a Novel Conotoxin That Blocks Molluscan Sodium Channels

A novel peptide toxin, PnIVB, isolated from the venom of Conus pennaceus blocks voltage-gated sodium current in Aplysia neurons. Complete blockade is obtained at a PnIVB concentration of 80±2.2 nM and 50% blockade at 16±0.86 nM. The potency of PnIVB in blocking Aplysia sodium current is four orders of magnitude larger than that of tetrodotoxin. The toxin has no paralytic activity when injected into fish. The rapid blockade of sodium current by PnIVB is not associated with a change in the activation or inactivation kinetics of the current, or with the reversal potential. Sodium current blockade is reversible after a 30 min wash with 50 times the bath volume. The novel conotoxin PnlVB can be used as a powerful tool for mollusc neurobiological research and as a molecular probe to explore the structure-function relations of voltage-gated sodium channel subtypes.     

血管夹对大鼠股动静脉损伤的实验研究

用１００、４５、１５ｇ力的血管夹，夹闭大白鼠股动静脉２０、６０和１２０ｍｉｎ，２４ｈ后观察其通畅情况，并经扫描电镜和光学显微镜观察股动静脉内皮细胞的损伤程度和血管内血栓形成。结果显示：前两种压力的血管夹在对股动脉只产生轻微损伤的情况下，对伴行股静脉可造成内皮细胞脱落，微小血栓形成等病理损伤。随夹闭血管时间的延长，内皮细胞损伤加重，血小板沉积和微血栓增多。血管夹对静脉的损伤和对其通畅率的影响尤应引起注意。     

高电压胸部摄影诊断和防护效果研究

作者以体模实验为基础。测定了不同管电压拍摄胸片时的病人剂量，考察了提高管电压对胶片影像质量的影响，结果表明，使用高电压拍摄胸片比使用低电压有利于降低病人剂量，在增加影像信息量，提高肋骨阴影区和纵膈区灶检出率方面更有较大优越性，此外，使用高电压技术不家利于延长Ｘ射线管的使用寿命。     

Fat metabolism and its response to infusion of insulin and glucose in patients with advanced chronic obstructive pulmonary disease

Summary. In order to investigate fat metabolism and the regulation of lipolysis and blood fuel metabolites by insulin, nine patients with chronic obstructive pulmonary disease (COPD) with chronic hypoxaemia and seven healthy control subjects of similar age were investigated by determination of the turnover rate of free fatty acids (TOR), using 1-¹⁴C-oleic acid as a tracer, and arterial concentrations of FFA, glycerol and 3-hydroxybutyrate. The measurements were performed in the basal state and during insulin and glucose infusion, aiming at euglycaemia at insulin levels of 50 and 100 mU l^-1. The subjects' ages were 64±2.7 and 66±1.1 (mean±SEM) years in the COPD and control groups, respectively. TOR was 0.73±0.06 and 0.52±0.02 mmol min^-1 (P<0.05) in the basal state, 0.33±0.04 and 0.30±0.02 at an insulin level of 50 mU I^-1 and 0.32±0.08 and 0.24±0.02 at an insulin level of 100 mU I^-1, in the COPD and control groups, respectively. Arterial FFA concentration was 0.98±0.08 and 0.75±0.06 mmol 1^-1 (P<0.05) in the basal state in the COPD and control groups, respectively. During the clamp, the decrease in FFA mirrored that in TOR. The results show that the state of lipolysis is increased in severe COPD patients with chronic hypoxaemia. Furthermore, the results suggest a reduced effect of insulin in lipolysis.