丹参主要活性成分防治骨质疏松症分子机制研究进展

丹参作为目前临床治疗骨质疏松症的常用中药之一?已有大量研究表明其具有防治骨质疏松症的作用? 现代药理学研 究发现?丹参及其活性成分可以从骨质疏松症进展的多个环节进行干预:促进间充质干细胞向成骨细胞分化?促进成骨细胞 的增殖和矿化作用?抑制成骨细胞的凋亡?纠正体内氧化应激状态促进骨形成?调节骨髓微环境成骨与成脂分化的平衡?抑制 破骨细胞的分化、增殖及骨吸收作用等? 涉及的信号通路?包括成骨细胞相关的ＢＭＰ/ Ｓｍａｄｓ 信号通路、Ｗｎｔ/ β￣ｃａｔｅｎｉｎ 信号通 路、ＥＲＫ 信号通路和ＰＩ３Ｋ/ ＡＫＴ 信号通路?以及破骨细胞相关的ＯＰＧ/ ＲＡＮＫＬ/ ＲＡＮＫ 信号通路及其下游的ＭＡＰＫｓ、ＮＦ￣κＢ 和 Ａｋｔ 信号通路? 为探讨丹参在体内抗骨质疏松作用的确切机制?以及为研究和开发抗骨质疏松新型药物?笔者就近年报道的 丹参主要活性成分防治骨质疏松症的分子作用机制作一综述?     

Wnt/β-catenin信号通路调控成骨细胞、破骨细胞在骨质疏松中的作用探讨

骨质疏松症是一种导致骨骼疏松、强度降低、易发生骨骼疼痛和脆性骨折的常见慢性病，影响了全球大部分中老年人健康。目前应用钙剂、维生素D补充剂、双膦酸盐类和雌激素等药物治疗，其主要侧重于预防、延缓骨吸收。针对骨质疏松症需要精准于细胞动力学和分化的靶向治疗药物。通过不断的探索和研究骨质疏松中涉及的信号通路，发现Wnt/β-catenin在骨正常生长和代谢中极为重要，β-catenin是介导成骨细胞存活和分化的关键分子。罗莫珠单抗、狄诺塞麦等新研发药物通过调节Wnt/β-catenin信号通路，进而影响骨髓间充质干细胞的成骨作用、成骨细胞的增殖和分化以及破骨细胞的生成等，参与骨质疏松的调节。本文就β-catenin在成骨细胞、破骨细胞功能调控和骨质疏松中的具体作用进行总结，进一步探讨Wnt蛋白和β-catenin的研究进展，以发掘更多创新的靶点来解决骨质疏松症的治疗问题。     

中药促进骨折愈合在细胞分子水平的研究进展

中药被广泛应用于治疗骨折和骨质疏松等骨科相关疾病,已有许多动物实验和临床试验证明中药,如淫羊藿、骨碎补等可刺激骨再生和抑制骨再吸收,最终促进骨折愈合。许多细胞实验证明这些中药成分可上调胞内成骨性转录因子和成骨相关基因产物表达,诱导前成骨细胞成骨分化和刺激成骨细胞增殖,促进骨结节形成和基质矿化。同时也可上调胞内破骨性转录因子和破骨相关基因产物表达,抑制前破骨细胞破骨分化和破骨细胞骨再吸收活性。此外这些中药成分还可影响胞内信号通路发挥以上相同的作用。由此发现前成骨细胞和前破骨细胞中的成骨性和破骨性转录因子、转录因子调节的基因表达和信号通路是中药促进骨折愈合的主要分子机制,也是目前中药促进骨折愈合的研究热点。     

miＲ 对骨质疏松骨代谢信号通路影响的研究进展

miＲ 在骨骼发育、代谢过程中具有重要的生物学功能,能够调控骨细胞生长、分化和功能表达。正常机体中,骨代谢相关信号通路对维持骨骼正常生物学功能意义重大,miＲ 通过与骨代谢相关的多种信号通路调节成骨细胞/破骨细胞代谢,达到有利于机体的平衡状态,如果 miＲ 表达失调这种稳态就会失衡,相关信号通路被激活,导致相应的骨代谢疾病,如骨质疏松症。信号通路作为调控骨代谢的重要途径,不同信号通路机制之间存在一定的联系,但是大多数信号通路的确切机制还不明了,各通路之间的相互联系研究较少,随着表观遗传学的发展,miＲ 通过相关信号通路精密调控骨代谢的机制被逐步阐明。miＲ 与多种骨质疏松多种信号通路存在密切的关系,成为潜在的检测标志物和治疗靶向点。研究 miＲ 参与调控骨质疏松骨代谢相关信号通路的机制,在骨质疏松的预防、诊治及预后意义重大。本文将从三个方面对近年来 miＲ 对骨质疏松症骨代谢相关信号通路的研究作以概述。     

miR对骨质疏松骨代谢信号通路影响的研究进展

miR在骨骼发育、代谢过程中具有重要的生物学功能,能够调控骨细胞生长、分化和功能表达。正常机体中,骨代谢相关信号通路对维持骨骼正常生物学功能意义重大,miR通过与骨代谢相关的多种信号通路调节成骨细胞/破骨细胞代谢,达到有利于机体的平衡状态,如果miR表达失调这种稳态就会失衡,相关信号通路被激活,导致相应的骨代谢疾病,如骨质疏松症。信号通路作为调控骨代谢的重要途径,不同信号通路机制之间存在一定的联系,但是大多数信号通路的确切机制还不明了,各通路之间的相互联系研究较少,随着表观遗传学的发展,miR通过相关信号通路精密调控骨代谢的机制被逐步阐明。miR与多种骨质疏松多种信号通路存在密切的关系,成为潜在的检测标志物和治疗靶向点。研究miR参与调控骨质疏松骨代谢相关信号通路的机制,在骨质疏松的预防、诊治及预后意义重大。本文将从三个方面对近年来miR对骨质疏松症骨代谢相关信号通路的研究作以概述。     

原发性骨质疏松症的骨骼免疫机制研究进展

原发性骨质疏松症是以骨质减少,骨的微观结构退化为特征的,致使骨的脆性增加以及易于发生骨折的骨骼疾病。其发病机制与多种因素相关,除了传统的内分泌机制之外,一种新的骨骼免疫机制已逐渐被深入研究:通过免疫细胞T淋巴细胞和B淋巴细胞、树突状细胞等,分泌多种细胞因子,并与多种细胞因子相互作用,通过信号通路的正负反馈调控,精细调节成骨细胞和破骨细胞的分化与增殖平衡,从而影响原发性骨质疏松症的发生。与破骨形成相关的T细胞,Th17细胞通过双重机制调控骨质吸收,Th1和Th2细胞亚群分别分泌IFN-γ和IL-4,通过抑制破骨细胞前体细胞发育成成熟的破骨细胞,从而抑制骨质吸收。Treg细胞通过表达CTLA-4,促进破骨细胞前体细胞的凋亡,抑制骨质吸收。B淋巴细胞通过调控RANKL和OPG的比例参与骨质代谢。树突状细胞既可以与CD4+T细胞结合,启动经典的RANKL/RANK破骨细胞形成的信号通路,参与骨质疏松的形成;也可以作为破骨细胞前体细胞的方式,在M-CSF等炎性因子的刺激下,直接分化为破骨细胞。现就这种免疫细胞与细胞因子精细调节骨质生成与骨质吸收平衡作用机制的最新研究进展进行阐述。     

续断提取物对骨质疏松性大鼠信号通路作用的研究进展

骨质疏松症(osteoporosis, OP)是骨吸收大于骨形成的骨代谢疾病,随着全球老龄化加重,严重威胁人类健康安全。续断作为传统补肾中药在防治OP方面具有广阔潜力,有关研究表明续断通过多靶点、多途径调控相关信号通路防治OP。最新药理学研究证明续断提取物木通皂苷D等成分可通过调控有关信号通路和促炎因子干预碱性磷酸酶、骨保护蛋白、骨钙素等蛋白因子表达,作用于成骨细胞、破骨细胞以及骨髓间充质干细胞有效防治OP。通过检索续断提取物防治OP的基础研究发现,续断提取物木通皂苷D、熊果酸、多糖类可以通过Wnt/β-catenin、MAPK、PI3K/AKT、BMP-Smads信号通路促骨形成,通过OPG/RANKL/RANK、雌激素信号通路抑制骨吸收防治OP。笔者就续断提取物调控不同信号通路,促进成骨细胞增殖,抑制破骨细胞分化,诱导骨髓间充质干细胞定向分化作一综述,为今后中医药防治OP的基础研究提供新思路。     

中药活性成分靶向激活AMPK防治骨质疏松症的研究进展

骨质疏松症作为一种慢性代谢性疾病影响中老年人的正常生活。临床上,防治骨质疏松症缺少靶点明确和药效显著的特效药已成为亟待解决的棘手难题。AMP活化蛋白激酶（AMPK）作为细胞的能量感受器,在骨质疏松的关键病因——骨重建失衡中发挥着重要作用,可以直接影响骨多细胞单位中骨髓间充质干细胞（BMSCs）、成骨细胞和破骨细胞,已有越来越多的研究发现并报道了中药活性成分靶向AMPK抗骨质疏松的作用和机制,取得了一定的研究成果。通过Web of Science、Pubmed、万方和中国知网数据库等对于近10年相关文献进行检索,搜集并整理最新的研究进展,对于BMSCs、成骨细胞和破骨细胞中AMPK的相关作用进行梳理,涉及BMSCs中Wnt/β-catenin、ERK、mTOR和Gfi1/OPN,成骨细胞中Wnt/β-catenin和BMP-2/Smad以及破骨细胞中c-Fos/NFATc1等不同的下游信号通路。以中药活性成分白藜芦醇、人参皂苷Rd、柚皮苷、芒柄花黄素、血根碱和高车前素等相关研究作为依据进行阐述和论证,为更好地发挥和探究中药及其活性成分靶向AMPK抗骨质疏松的作用机制提供新思路。     

抗骨质疏松药物的研究进展

骨质疏松(osteoporosis)是一种最为常见的代谢性骨病,主要表现为骨量减少、骨组织微结构破坏从而导致骨痛、骨脆性及骨折危险性增加。目前临床常用抗骨质疏松药物可分为骨吸收抑制剂、骨形成剌激剂及骨矿化药物。选择性雌激素受体调节剂（SERMs)作为一种新型骨吸收抑制剂,于骨骼系统表现为雌激素激动剂作用,于乳腺等组织表现为雌激素拮抗剂作用,从而不增加致癌风险。骨保护素（OPG)及抗RANKL单克隆抗体可与核因子KB受体活化因子（RANK)竞争结合其配体 (RANKL),从而抑制破骨细胞骨重吸收作用。C-src激酶抑制剂可阻断破骨细胞的细胞内信号转导通路从而不能形成完整的细胞骨架,氯离子通道阻滞剂可破坏破骨细胞骨吸收酸性微环境,αVβ3整合素抗体及其受体拮抗剂可减弱破骨细胞与骨组织粘附,组织蛋白酶K抑制剂可减少骨胶原裂解,从而均有待于成为新一代骨吸收抑制剂。新型骨形成剌激剂主要包括PTH 片段制剂、钙离子敏感受体激动剂、骨硬化蛋白中和抗体、他汀类药物等。其中钙离子敏感受体激动剂于成骨细胞可通过促分裂原活化蛋白激酶(MAPK)通路来促进成骨细胞的骨形成作用,于破骨细胞可能通过RANKL信号通路以诱导破骨细胞凋亡。骨硬化蛋白中和抗体可抑制骨硬化蛋白与低密度脂蛋白受体相关蛋白（LRP)5/6结合,从而保证Wnt信号通路在骨形成及重建中发挥作用。他汀类药物则通过增强机体内骨形态发生蛋白-2基因表达以增加骨强度,减少骨折发生。本文就目前新型骨吸收抑制剂及新型骨形成剌激剂的研究进展作一综述。     

分子信号通路在骨质疏松症发生机制中的研究进展

目的骨质疏松症正成为影响老年人健康的老年疾病之一,主要原因是骨吸收大于骨形成,成骨细胞数量减少和活性下降。目前研究重点主要通过调节骨合成代谢的信号传导通路,抑制破骨细胞骨吸收,降低骨转换以达到减少骨量丢失。本文总结了骨代谢相关调控通路,包括MAPK信号转导途径、Notch信号通路、Wnt/-catenin信号途径、BMPs信号通路、PPAR-r信号通路、TGF-信号通路和Hedgehog信号转导途径。多个信号通路相互交叉,共同参与通路中相关因子的调节,通过激活或抑制一些关键环节的细胞因子,在骨代谢过程中发挥了主要作用。     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

Immunomodulation in Transplantation with Photopheresis

Abstract: Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoacti-vatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregula-tory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.