DNA甲基化与胆囊癌

DNA甲基化是真核生物的正常修饰方式,异常的DNA甲基化与肿瘤的发生发展密切相关,具有重要生物学意义.胆囊癌中肿瘤相关基因启动子的异常甲基化,作为表观遗传标记物,在胆囊癌的发病、诊治、疗效观察及预后判断等方面可能发挥重要作用.     

循环游离DNA在前列腺癌诊疗中的研究进展

循环游离DNA(cfDNA)是一种存在于多种体液中的小分子DNA片段。在前列腺癌患者中,cfDNA主要由肿瘤细胞凋亡后释放入外周血。cfDNA的浓度、基因甲基化突变以及雄激素受体拷贝数变异等特征,都对前列腺癌患者的早期筛查与诊断、预后及耐药性的评估有重要意义。本文概述cfDNA应用于前列腺癌诊疗中的最新研究进展。     

乳腺癌基因甲基化的研究进展

乳腺癌的发生的分子机制仍然不明确。研究显示表观遗传学改变（Epigenetics）所导致的基因表达异常也是乳腺癌发生、发展的重要原因。表观遗传学改变是基因的核苷酸序列不发生改变的情况下基因表达的可遗传的变化,包括DNA甲基化、组蛋白乙酰化、染色质重塑、基因组印记以及非编码RNA等。乳腺腺的DNA甲基化是常见的分子事件,具有独特的DNA甲基化特征,既往的研究发现DNA甲基化可以作为乳腺癌早期诊断、分型、监测药物治疗效果和预后的分子标志物。本文将对DNA甲基化在乳腺癌的研究进展进行综述。     

DNA甲基转移酶的作用及甲基化在肿瘤发生中的作用

表遗传学(epigenetics)调节与肿瘤相关基因的转录调控密切相关.DNA甲基化就是基因表遗传学调节的重要机制之一.DNA异常甲基化与肿瘤的发生和演进关系密切,而DNA甲基化是由DNA甲基转移酶(DNA methyltransferase,DNMT)催化发生并维持的.因此,深入研究DNA甲基转移酶的作用对认识异常甲基化的发生以及异常甲基化在肿瘤的发生和演变中的作用有着重要意义.     

乳腺癌WWOX基因表达缺陷的意义及其与CpG岛甲基化的关系

目的 研究WWOX蛋白在乳腺癌组织和细胞系中的表达变化,分析其与WWOX基因启动子和第一外显子CpG岛甲基化的关系.方法 应用免疫组织化学染色检测乳腺癌组织和细胞系中WWOX蛋白表达,采用甲基化特异性PCR(methylation-specific PCR,MSP)分析乳腺癌组织和细胞系中WWOX基因CpG岛甲基化状况.结果 32.2%的乳腺癌组织和5.4%正常乳腺组织中WWOX蛋白表达缺失,差异有统计学意义(P＜0.01).乳腺癌组织WWOX表达异常与绝经后状态(P＜0.01)关系密切.Ⅰ、Ⅱ、Ⅲ期患者中WWOX蛋白表达缺失的比例分别为23.1%、28.6%和46.2%.55%的乳腺癌组织WWOX启动子CpG岛甲基化扩增,45%的乳腺癌组织WWOX第一外显子CpG岛甲基化扩增,癌旁组织中未出现CpG岛甲基化扩增.MDA-MB-231细胞WWOX基因CpG岛完全甲基化,而MCF-7细胞无甲基化产物扩增.结论 乳腺癌中广泛存在着WWOX基因CpG岛甲基化,是WWOX表达缺陷的重要机制,并且可能通过性激素受体信号途径在乳腺癌的发生、发展中发挥作用.     

腺瘤性息肉病基因DNA甲基化在食管癌患者肿瘤组织及血浆中的表达

目的 探讨食管鳞癌患者肿瘤组织及外周血游离DNA中腺瘤性息肉病（APC）基因甲基化状态与临床病理特征的关系．以及外周血APC甲基化围手术期的动态变化。方法应用实时定量MSP技术检测76例食管鳞癌患者肿瘤组织、配对的癌旁正常组织以及术前1d、术中及术后7d外周血游离DNA中APC基因的甲基化状态。选取60名年龄性别配对的健康志愿者外周血浆DNA作对照。结果食管鳞癌患者肿瘤组织及外周血游离DNA中APC基因甲基化率分别44．74％（34／76）和42．11％（32／76）,明显高于癌旁组织及健康对照组[（6．58％（5／76）和1．67％（1／60）,均P=0．000]。APC基因甲基化率在外周血与肿瘤组织中具有良好的一致性,其ROC曲线Youden指数为0．849（P=0．000）。APC基因甲基化分别与患者病理分期、淋巴结转移、浸润深度及神经脉管浸润有关（P〈0．05）：家族肿瘤史是与外周血游离DNA中APC甲基化有关的独立因素（P〈0．05）。术前、术中、术后血浆中DNA甲基化发生率呈现先升后降的变化趋势。结论食管鳞癌患者外周血游离DNA中APC甲基化率可反映肿瘤进展状态．并随肿瘤实体的摘除而下降。     

循环游离DNA在前列腺癌中的研究进展

循环游离DNA(cell-free DNA,CF-DNA)可由正常细胞和肿瘤细胞释放,其中肿瘤细胞来源的游离DNA又叫做循环肿瘤DNA(circulating-tumor DNA,CT-DNA),以细胞外游离形式存在于血液、尿液等体液中。在前列腺癌(PCa)患者中,CF-DNA的浓度明显高于健康对照组,而且存在与原位肿瘤相似或完全相同的基因突变、超甲基化、基因不稳定性等变化特征,对肿瘤的早期诊断、术后检测以及对靶向药物的疗效评估都有着潜在作用,是新兴的肿瘤标志物研究热点。本综述简要阐述CF-DNA的生物学特性、检测以及作为肿瘤标志物的新进展。     

食管癌患者肿瘤组织及外周血中上皮细胞钙黏蛋白及Ras相关区域家族1A基因甲基化的研究

目的 探讨血浆上皮细胞钙黏蛋白( CDH1)基因及Ras相关区域家族1A基因( RASSF1A)甲基化对食管癌手术彻底程度的参考价值及其与食管癌临床病理特征的关系.方法 应用Real-time甲基化特异性聚合酶联反应技术(MSP)技术对76例食管鳞癌患者肿瘤组织、配对的癌旁正常组织、术前、术中及术后外周血游离DNA中CDH1及RASSF1A基因的甲基化状态进行检测.结果 CDH1及RASSF1A甲基化率在食管癌肿瘤组织中分别是72.37％、55.26％;在血浆中分别是63.16％、50.00％,且与病理分期、淋巴结转移及神经脉管浸润显著相关(P值均＜0.01);术前、术中、术后血浆中DNA甲基化发生率呈现先升后降的变化趋势.结论 食管鳞癌患者外周血游离DNA中CDH1及RASSF1A甲基化可反映机体的荷瘤状态,并可作为食管鳞癌手术彻底程度的标志物.     

乳腺癌组织Ras相关区域家族1A基因启动子甲基化状态及临床意义

目的 探讨Ras相关区域家族1A基因(RASSF1 A)启动子甲基化在乳腺癌发生发展中的作用.方法 甲基化特异性聚合酶链反应(MS-PCR)法分析44例乳腺癌石蜡包埋切片组织中RASSF 1A基因启动子甲基化状况,分析甲基化与临床病理特征之间的关系.结果 44例乳腺癌组织切片中有25例RASSF1A基因启动子发生了超甲基化,甲基化率为56.8％,启动子甲基化与患者年龄明显相关(P＜0.05),与患者月经初潮年龄和生育次数无相关,与肿瘤大小、淋巴结转移、TNM分期及雌激素受体(ER)、孕激素受体(PR)之间无相关.结论 RASSF1A启动子甲基化为乳腺癌中的频发事件,其发生率随着年龄增长而升高,在乳腺癌发生中起重要作用.     

胆管癌相关基因甲基化研究进展

目的总结胆管癌相关基因甲基化谱的研究进展,阐述DNA甲基化研究对胆管癌的临床诊断价值和治疗意义。方法分析近年来有关胆管癌相关基因异常甲基化与胆管癌关系的文献报道。结果胆管癌的发病是多基因异常表达的结果,目前已发现许多肿瘤相关基因甲基化异常与胆管癌的发生密切相关。表基因的改变可能是胆管癌发生过程中非常重要的机理。结论胆管癌相关基因甲基化异常与胆管癌的发生关系密切,胆管癌相关基因异常甲基化检测有望为胆管癌的早期无创诊断提供新的途径。改变DNA甲基转移酶活性和胆管癌相关基因甲基化状况可作为胆管癌辅助治疗的一种新思路。     

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.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.