自噬在骨质疏松与骨稳态中作用的研究进展

骨质疏松症是与年龄相关的全身系统性骨代谢疾病。随着年龄增加,骨形成受抑制骨破坏增加导致骨量降低与骨折易感性。骨质疏松症形成的分子机制较为复杂,其中自噬与骨质疏松形成之间的关系一直是近年热点研究话题。自噬是高度保守的真核细胞物质循环过程,通过降解大分子物质、蛋白质、细胞器,并对降解产物循环利用,保持细胞在应激、能量缺乏等不利环境中稳定生存。随着人们对自噬研究的不断拓展,自噬水平的分子调控通路及其在细胞生理与疾病发展中的作用取得了众多进展,包括神经退行性疾病、癌症、糖尿病、心肌疾病等。许多动物体内外及人体研究显示自噬与包括骨质疏松症在内的骨骼疾病存在着很大关联。自噬在骨组织各细胞增殖、分化、凋亡及保持稳定等多方面扮演重要角色,深度参与骨重塑过程。骨组织各细胞在衰老、活性氧累积、雌激素水平下降、全身炎症水平增高等多种不利因素影响下,自噬水平发生不同程度的改变,导致骨代谢与骨稳态失衡并逐步发展为骨质疏松症。该文在现有的相关文献报告基础上,对自噬与骨稳态、骨质疏松症的关系进行综述,以期对进一步研究提供参考。     

自噬相关miRNAs、lncRNAs、circRNAs在骨质疏松症中的作用

骨质疏松症由骨吸收增加和骨形成减少引起,是一种常见代谢性骨疾病,其发生发展的详细分子机制尚不清晰。自噬作为一种应激反应性分解代谢过程,在维持细胞和组织稳态中起着关键作用。非编码RNAs,如微小RNAs、长链非编码RNAs和环状RNAs,通过作为调节因子对基因表达进行转录后调控,在包括自噬在内的许多细胞过程中发挥重要作用。研究表明,部分自噬相关ncRNAs通过调节骨髓间充质干细胞、成骨细胞、骨细胞和破骨细胞生理和发育过程参与维持骨稳态。基于此,本文综述了影响骨微环境的自噬相关微小RNAs、长链非编码RNAs和环状RNAs参与调控骨质疏松发生发展的最新研究进展,为探索骨质疏松症发病机制和确定临床治疗潜在靶点提供理论基础。     

中药干预骨质疏松症细胞自噬的研究进展

骨质疏松症是多种病理因素共同作用导致的全身性骨代谢疾病,较高的发病率、致残率以及发病机制尚未明确使该病的防治成为棘手的公共卫生难题。随着现代医学对该病的研究日趋深入,发现细胞自噬在骨质疏松症的发生发展中扮演重要角色。自噬作为机体必不可少的细胞机制,通过清除衰老受损的细胞器和错误折叠的蛋白质,以确保实现细胞稳态以及细胞器的自我更新。在骨质疏松症的进展过程中,自噬不仅参与了成骨、破骨以及骨髓间充质干细胞的增殖分化、功能发挥过程,在维持骨稳态方面更是充当了至关重要的调控角色。虽然骨质疏松症与自噬之间的可能联系及相互作用机制不断被揭示,但以此为切入点的药物靶点设计尚未展开。中药防治骨质疏松症优势明显,效果显著,并且诸多研究证实中药可通过激活自噬相关途径来调控细胞自噬水平,在神经退行性疾病、代谢相关疾病、心脑血管疾病及肿瘤防治等研究领域发挥作用,因此有效调节细胞自噬水平已成为中药防治骨质疏松症新的靶向研究策略。本文就中药对骨质疏松症细胞自噬的影响及最新进展进行综述,以期为中药防治该病提供新的理论依据。     

Fas/Fas-L信号系统在绝经后骨质疏松症中作用的研究进展

Fas/Fas-L信号系统是外源性凋亡通路的重要组成部分。近年来大量研究发现,Fas/Fas-L信号系统通过诱导细胞凋亡,不仅参与了免疫系统稳态的维持,而且在骨内环境稳态的调节中也发挥了重要的作用。Fas/Fas-L信号系统在不同骨细胞上的表达和分布可能随体内雌激素水平波动而发生变化。当绝经后雌激素分泌不足时,Fas/Fas-L信号系统可通过启动骨细胞外源性凋亡通路,介导成骨和破骨平衡向破骨方向偏移,参与绝经后骨质疏松症的发生发展。通过调节骨细胞上Fas/Fas-L信号系统来平衡破骨细胞骨吸收和成骨细胞骨形成,将为绝经后骨质疏松症的治疗提供新的思路。     

自噬在糖皮质激素性骨质疏松症中的作用机制

糖皮质激素性骨质疏松症（glucocorticoid-induced osteoporosis,GIOP）由长期或过量应用糖皮质激素（glucocorticoid,GC）所导致,其发病与骨质疏松症（osteoporosis,OP）相比有其自身特点。基于细胞自噬与OP的相关研究,探讨自噬与GC及GIOP三者之间的关联性。研究发现,在GC导致GIOP形成的过程中,针对不同GC浓度、不同细胞（BMSC、OB、骨细胞、OC）等,通过不同信号通路介导的细胞自噬发挥着复杂作用。要依据自噬对骨形成的积极作用开展GIOP的相关治疗,需要考虑多因素,将自噬水平精确调控在一个相对稳态范围内。     

IL-1与骨质疏松研究进展

骨质疏松症已经成为与衰老相关的最重要的疾病之一。女性发生率高的原因是由于绝经后雌激素水平的降低伴有骨吸收的增加。最新的研究显示,免疫系统可能是参与绝经后骨质疏松的重要因素,作用于成骨细胞及破骨细胞的促炎因子,以及免疫系统的激活被认为是引起骨质疏松的危险因素,其中白介素-1(IL-1)作为强有力的破骨细胞刺激因子,在生理状态下以及炎症性疾病、绝经后全身性骨量丢失中均发挥着重要作用。本文就IL-1家族、IL-1在细胞、信号通路、动物模型等方面的文献进行回顾,并就IL-1抑制剂、拮抗剂及其衍生物对骨代谢作用进行综述。     

自噬对骨质疏松症骨代谢的影响研究

自噬的紊乱会引起成骨和破骨平衡失调,从而导致骨质疏松。研究表明自噬在一系列退行性疾病中具有重要性,通过对成骨细胞、破骨细胞以及骨细胞的调控,对维持骨骼强度,预防骨质疏松的发生发挥着至关重要的作用。本文就自噬与骨质疏松之间的关系作一综述,对其在骨质疏松症发病过程中的作用机制进行探讨。     

骨免疫与绝经后骨质疏松妇女骨重建失衡

绝经后骨质疏松是因雌激素水平下降引起骨免疫功能增强,导致骨重建失衡所致。成骨细胞和破骨细胞相互作用是调控骨重建的核心因素,而RANKL/RANK/OPG系统是连接骨与免疫系统之间的分子桥梁,在调节骨吸收和骨形成耦联中发挥关键作用。骨细胞和免疫细胞通过共同的细胞因子及受体相互作用,调节骨代谢平衡,以共同的骨代谢转录因子和信号分子调控骨重建过程。雌激素作为骨细胞与免疫细胞的共同交叉机制,通过经典性激素受体途径调控T细胞活化,介导免疫因子的产生和表达,影响免疫细胞、成骨细胞、破骨细胞的活性和功能,既有正性调节作用,又有负性调节作用,决定骨重建方向。因此,骨免疫在调控绝经后骨质疏松症骨重建失衡中发挥重要作用。补肾法是中医药治疗绝经后骨质疏松症的根本治则,长期临床应用疗效显著,其作用机制可能是通过干预骨免疫而调节骨重建失衡,为治疗绝经后骨质疏松症提供新的切入点。     

细胞焦亡对骨稳态的影响及展望

人体的骨代谢主要依靠成骨细胞的骨形成作用和破骨细胞的骨吸收作用来达到平衡，在骨代谢的过程中还有其他细胞因子、激素等参与来协助这一过程，如果骨代谢出现失衡，则会出现致残率和致死率逐年上升的骨代谢性疾病骨质疏松症。细胞焦亡作为一种新型的程序性细胞死亡的方式近年来备受关注，其效应蛋白gasdermin D（GSDMD）通过与细胞膜结合形成穿孔效应，导致细胞不断肿胀直至细胞膜破裂，释放大量炎症因子。细胞焦亡的机制不同于传统的凋亡、自噬等其他细胞死亡方式，已有研究表明细胞焦亡在感染性疾病、肾脏疾病、心血管疾病等发挥了重要作用，但是在骨代谢性疾病中鲜有报道。笔者就细胞焦亡对骨稳态的影响进行综述，以利于对骨质疏松的深入研究提供新的思路。     

自噬在骨稳态与骨质疏松症中的作用及机制研究进展

骨质疏松症（osteoporosis, OP）是一种与年龄密切相关的全身性、系统性骨代谢疾病。近年来,OP发病率逐年升高,其并发症如骨质疏松性骨折的发病率和死亡率也随之升高,使家庭与社会负担加重,逐渐成为世界性医学难题。自噬是一种重要的细胞行为,真核细胞在生理或病理条件下通过细胞自噬降解自身蛋白质或受损细胞器以维持细胞稳态和正常功能。国内外学者指出自噬在骨稳态及多种骨骼系统疾病例如OP的发生发展中有重要的调控作用。本文就国内外文献报告中有关自噬与骨质疏松症相关的研究成果进行综述,期望为进一步研究及发展临床治疗方法提供借鉴。     

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.     

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.     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.