胆汁流变与胆石形成

胆汁流变与胆石形成江艺，吴爱平，迟彦邦一、流体的基本流变特性［１，２］流体分两种，牛顿流体和非牛顿流体。牛顿流体是指温度不变，流体种类一定，其流动时，流体内摩擦力即切应力（τ）改变同流动速度梯度（ｒ）变化之比为常数（ｎ）。该常数称动力粘性系数或粘度。...     

静态混合环流式多糖生物反应器研究

在静态混合环流式反应器内，发现高表现粘度的黄原胶水溶液中（７．０～８．０Ｐａ·Ｓ），ＳＬ型静态混合器对提高ｋ＿Ｌα比ＳＫ型有利。经黄原胶发酵试验，最终发酵液胶浓平均３．０２％，反应器电耗６６２０ｋｗｈ／ｔ胶。在剪切速率约为２００ｓ￣（－１）的高剪切区内进行气液混合，有利于气液固之间的质量传递和能耗的降低。     

不同浓度安氟醚对低温下心肌能量代谢的影响

目的 研究不同浓度安氟醚（Ｅｎｆ）对常温或低温下心肌能量代谢的影响。方法 ２４只家兔的离体心脏，Ｌａｎｇｅｎｄｏｒｆｆ装置平衡灌注１５ｍｉｎ后，随机分为４组（ｎ＝６），Ａ组，常温１．１％Ｅｎｆ的Ｋ－Ｈ液灌注；Ｂ组，常温２．２％Ｅｎｆ的Ｋ－Ｈ液灌注；Ｃ组，低温１．１％Ｅｎｆ的Ｋ－Ｈ灌注，Ｄ组，低温２．２％Ｅｎｆ的Ｋ－Ｈ液灌注。常温组温度为３７℃，低温组温度为３０℃。灌注３０ｍｉｎ后，取心失部心肌组织     

硫酸镁与氯胺酮相互作用的实验研究

序贯法测得小鼠静注（ｉｖ）、腹腔注射（ｉｐ）硫酸镁（Ｍａｇｎｅｓｉｕｍ　ｓｕｌｆａｔｅ，ＭＳ）的ＬＤ５０分别为１９５（１５９～２３８）和８３６（７１６～９７７）ｍｇ／ｋｇ。小鼠ｉｖ氯胺酮（Ｋｅ－ｔａｍｉｎｅ，Ｋｅｔ）的ＬＤ５０为８０．０（７３．１～８８．２）ｍｇ／ｋｇ；预先ｉｖＭＳ２０、４０ｍｇ／ｋｇ后再ｉｖＫｅｔ之ＬＤ５０分别为７５．０（７０．２～８０．１）和６９．６（６５．６～７３．８）ｍｇ／ｋｇ，仅后者比单独ｉｖ　Ｋｅｔ组之ＬＤ５０小（Ｐ＜０．０５）。对照组免（ｎ＝１０）ｉｖ　Ｋｅｔ１０ｍ…     

聚氯乙烯通过矩形口模挤出时离模膨胀的研究

研究了ＰＶＣ材料通过矩形口模挤出时，口模的几何参数和剪切速率对离模膨胀的影响，并从理论上分析了其特征规律。     

进展期胃癌患者脾脏的细胞免疫状态

本文检测了进展期胃癌患者（ｎ＝１６）脾静脉血淋巴细胞（ＳＶＬ）和脾细胞（ＳＣ）的自然杀伤细胞（ＮＫ）、淋巴因子激活的杀伤细胞（ＬＡＫ）的杀伤活性及Ｔ细胞（ＴＣ）亚群，与胃良性病变（ｎ＝７）的ＳＶＬ及外伤性脾破裂（ｎ＝６）的ＳＣ对照比较，探讨进展期胃癌（ＡＧＣ）患者脾脏的细胞免疫状态，为胃癌术中合理的处理脾脏提供免疫学依据。结果表明：ＡＧＣ患者脾脏的ＮＫ、ＬＡＫ细胞杀伤活性显著降低（Ｐ＜０．０２，Ｐ＜０．０１）；ＣＤ４显著减少，ＣＤ８显著增加，ＣＤ４／ＣＤ８比值显著降低（Ｐ＜０．０２～０．０１）。提示进展期胃癌患者脾脏的细胞免疫功能受到明显抑制。     

Brookfield粘度计测定微生物多糖发酵液流体特性参数

以典型的假塑性流体黄原胶和威伦胶为测试标样,通过Brookfield粘度计测量流体在不同转速下的粘度,结合推导的数学公式,求得非牛顿流体的流变特性参数.建立的方法可以用于测定发酵液的流变特性参数 n和浓度系数k ,并建立了流变学参数与多糖浓度的函数关系,根据计算结果推导出的模型能够评价流体的流变性能,所采用的数据处理方法及所获得的结论对非牛顿流体的研究具有一定的意义.     

稀油包水多分散微乳液的动态光散射

分析了满足Ｒａｙｌｅｉｇｈ－Ｇａｎｓ－Ｄｅｂｙｅ（ＲＧＤ）近似条件的稀多分散壳层球粒悬胶液，导出了一个新的作为溶剂折射率ｎ＿ｏ函数的“测量”静态结构函数Ｓ￣Ｍ（Ｋ），并用以计算稀悬胶液的多分散性分布。同时导出了联系粒子互扩散和自扩散系数的“测量”平均扩散系数。     

氯胺酮—异丙酚静脉复合麻醉

选择２８例ＡＳＡⅠ￣Ⅱ级、非心脏手术病人，随机分为氯胺酮－异丙酚静脉复合麻醉（Ｋ组，ｎ＝１４）和芬太尼－异丙酚静脉复合麻醉（Ｆ组，ｎ＝１４）。无术前用药。静注氯铵酮（Ｋ组）或芬太尼（Ｆ组）、维库溴铵和异丙酚诱导，气管插管。持续静脉泵入氯胺酮（Ｋ组）或芬太尼（Ｆ组）复合静滴异丙酚维持麻醉。结果诱导后Ｋ组血压（ＢＰ）和心率（ＨＲ）下降明显小于Ｆ组，但气管插管反应明显大于Ｆ组。Ｋ组麻醉后完全清醒时间较Ｆ     

半流质高能食品的流变学特性

半流质高能食品是一种特殊的食品,流变学性质是其质量评价体系中一个重要的方面,实验研究了样品在不同温度下的流变学特性.当温度一定时,半流质高能食品的粘度随剪切速率的增大而降低,具有剪切稀化现象.不同温度下的半流质高能食品的流变学模型不同:10～30℃时的流变学模型为y=mxn-1,而温度在40～50℃时的流变学模型是y=A+mln(x).比较了热处理前后样品的粘度随温度变化的规律,结果表明,热处理后的样品粘度曲线呈现平滑下降走势,而热处理前样品的粘度曲线会出现明显的波折.     

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.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

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.