芪藿肾宝抗泼尼松所致大鼠松质骨结构破坏的作用

目的观察芪藿肾宝对糖皮质激素引起松质骨结构破坏的防治作用。方法选用３月龄ＳＤ雄性大鼠２４只，随机分为对照组、激素组和治疗组。激素组用泼尼松４．５ｍｇ／ｋｇ灌胃，每周二次。治疗组给予芪藿肾宝０．３８ｇ／ｋｇ，每周６次，持续９０天。扫描电镜观察大鼠腰椎松质骨结构的改变。结果与正常组比较，激素组的大鼠骨小梁变少，变细，断裂，连接不紧密，表面常见骨吸收形成的陷窝。治疗组大鼠骨小梁粗大，排列整齐，连接紧密。结论芪藿肾宝能有效防止糖皮质激素所引起的松质骨三维结构的损害，保持骨的正常力学强度，避免骨折。     

中药复方护骨胶囊对糖皮质激素诱导骨质疏松 大鼠骨密度和骨形态计量学的研究

目的 探讨中药复方护骨胶囊(主要由制何首乌、淫羊藿、熟地黄等多味中药加工而成的复方制剂)对糖皮质激素诱导骨质疏松大鼠骨丢失的影响.方法 3月龄SPF级雄性SD大鼠30只,随机平均分为3组:正常对照组(Nrm)、激素组(Met)和中药组(CH).Met组:皮下注射甲强龙(Met)5mg/kg/d,每周5次;CH组:在Met组基础上给予中药复方护骨胶囊(150 mg/kg/d)灌胃,实验期12w.大鼠右侧股骨和腰椎行骨密度(BMD)测定,右侧胫骨行骨形态计量学分析.结果 Met组腰椎和股骨BMD显著低于Nrm组;CH组腰椎和股骨BMD显著高于Met组.Met组Tb.N、%Tb.Ar、MS/BS、MAR和BFRs显著低于Nrm组,Tb.Sp、ES/BS显著高于Nrm组;中药组Tb.N、%Tb.Ar、MS/BS、MAR和BFRs显著高于Met组,Tb.Sp,ES/BS显著低于Met组.结论 中药复方护骨胶囊在提高激素诱导骨质疏松大鼠的骨密度,促进骨形成,降低骨吸收,延缓骨丢失方面有积极作用,对继发性骨质疏松的预防和治疗有一定前景.     

糖皮质激素对肾小球疾病患者骨代谢影响因素的研究

目的　探讨长期应用糖皮质激素 (GC)治疗对肾小球疾病患者骨代谢影响的因素。方法　 2 0 7例肾小球疾病患者 ,应用常规剂量GC治疗 ,于治疗前及治疗后每隔 3～ 6个月 ,进行了 35 7例次腰椎和股骨近端骨密度 (BMD)、血钙、血磷和骨钙素浓度测定。结果　①用GC后骨钙素浓度明显降低 (P均 <0 0 0 5 ) ,但其不能预测BMD下降。②用药 15个月后男性各部位BMD均减少 (32 2～111 5 )mg/cm2 ,以L1 4和股骨粗隆更明显 (P均 <0 0 5 ) ,骨丢失率 3 3%～ 10 3% ;女性L1 4BMD均减少(4 3 8～ 76 0 )mg/cm2 ,以L1更明显 (P <0 0 5 ) ,骨丢失率 3 9%～ 7 9%。③年龄与各部位BMD变化呈负相关 ,但不影响GC造成的骨丢失。男性各部位、女性L1 4BMD减少与GC累计剂量和GC用药时间负相关。④用GC15个月 (GC累计剂量 10g以上 ) ,男性L1 4BMD正常的比例从 3/ 4至 3/ 5 ;女性L1和L2 BMD正常者从 3/ 4减少到 1/ 2。结论　长期口服糖皮激素导致与剂量和用药时间相关的腰椎和男性股骨粗隆骨丢失 ,年龄偏大和男性患者骨丢失更明显。     

复方贞术调脂胶囊对糖皮质激素诱导骨质疏松大鼠股骨和腰椎骨密度及生物力学特性的研究

目的观察复方贞术调脂胶囊(FTZ)对糖皮质激素诱导骨质疏松大鼠股骨和腰椎骨密度及生物力学特性的影响。方法SPF级雄性SD大鼠32只,随机等分为4组:Nrm组为正常对照组,Met组为皮下注射甲强龙(Met)5 mg/(kg·d),每周5次,FTZL组和FTZH组在Met组基础上每日分别给予低剂量FTZ(1.5g/kg)和高剂量FTZ(6g/kg)灌胃,实验期为12w。QDR4500A型双能X线骨密度测定仪测定股骨和腰椎骨密度,MTS-858型生物力学实验机测定股骨和腰椎生物力学性能。结果Met组大鼠股骨和腰椎的骨密度、最大载荷、刚度、弹性模量、皮质骨厚度、股骨中段截面面积和椎体横断面面积均显著低于Nrm组相应指标(P0.001,P0.01),股骨骨髓腔面积显著高于Nrm组(P0.01);FTZL组大鼠的股骨骨密度,最大载荷、刚度、弹性模量、皮质骨厚度、股骨中段截面面积和椎体横断面面积较Met组有升高趋势,股骨骨髓腔面积较Met组减少,但两组间各指标均无显著性差异(P0.05);FTZH组大鼠股骨和腰椎的骨密度、最大载荷、刚度、弹性模量、皮质骨厚度和椎体横断面面积显著高于Met组相应指标(P0.01,P0.05),股骨骨髓腔面积显著低于Met组(P0.05),股骨中段截面面积较Met组有增加趋势,但无显著性差异(P0.05),FTZH组腰椎的骨密度和最大荷载显著高于FTZL组(P0.05),余各项指标间无显著性差异(P0.05)。结论高剂量FTZ对改善糖皮质激素诱导骨质疏松大鼠股骨和腰椎的骨密度及生物力学特性效果显著。     

骨量、微结构及受力方向对去卵巢大鼠骨生物力学的影响

目的观察骨质疏松模型大鼠骨量、骨微结构和骨的受力方向与生物力学变化的关系。方法6～7月龄Wistar大鼠50只,随机分为正常对照组25只,去势模型组25只,12周后处死全部大鼠,测定大鼠全身、股骨和腰椎(L4～L6)骨密度,对左侧股骨进行三点弯曲试验,右侧股骨沿载荷倾斜20°角进行压力试验,对椎体(L4)进行压缩试验,把部分股骨和腰椎(L5)制成切片进行免疫组化染色,观察它们的形态计量学变化。结果去势组大鼠的全身、股骨和腰椎(L4～L6)骨密度比对照组明显减少(P<0.05),去势组大鼠右侧股骨沿载荷倾斜20°角后的结构力学性能和椎体的最大压缩力较正常对照组明显降低(P<0.05),但两者左侧股骨的结构力学性能差异无显著性(P>0.05),去势后大鼠股骨的材料力学性能较对照组明显下降(P<0.05),组化染色显示去势组大鼠的骨小梁较正常组稀疏减少,尤以松质骨明显。结论大鼠去势后松质骨的骨量、骨微结构较皮质骨变化明显,且骨量、骨微结构和骨的受力方向对骨的生物力学都有着重要影响。     

川牛膝在去卵巢大鼠体内的骨保护作用

目的 观察川牛膝在去卵巢大鼠体内的抗骨质疏松作用。方法 3月龄雌性SD大鼠50只随机分为5组:假手术组 (SHAM)、单纯去卵巢组（OVX)、己烯雌酚组（ERT组,22.5μg/kg? d,ig)、高剂量川牛膝组（CH,14 g/kg? d,ig)、低剂量川牛膝 组(CL,7 g/kg? d,ig)。其中,40只大鼠切除双侧卵巢,SHAM组仅切除卵巢周围等量脂肪组织,术后第8天开始给药,给药12 周后处死所有大鼠,测定腰椎骨密度（L-BMD)、股骨骨密度（F-BMD)及骨生物力学性能：弹性模量（ELASTIC)、刚度 (STIFFNESS)、最大应力（M-STRESS)及最大承载力（M-LORD),并测定血清钙（Ca)、磷（P)、碱性磷酸酶(ALP)、尿羟脯氨酸 (HOP )、肌酐(Cr)值。结果 高剂量川牛膝组及己烯雌酚组大鼠腰椎和股骨的骨密度及骨生物力学性能均高于OVX组（P <0. 05),而尿羟脯氨酸/肌酐值及血清Ca、P含量低于OVX组（P <0.05)。结论 川牛膝在去卵巢大鼠体内能抑制骨量丢失、改善骨生物力学性能,预防骨质疏松的发生。     

rhPTH(1-34)治疗糖皮质激素诱发大鼠骨质疏松症的实验研究

目的 观察重组人甲状旁腺激素(1-34)[recombinant human parathyroid hormone(1-34),rh-PTH(1-34)]对糖皮质激素引起的大鼠继发性骨质疏松症(OP)的治疗作用。方法 应用肌肉注射地塞米松(dexamethasone.DEX)方法,建立模拟糖皮质激素引起的继发性OP大鼠模型。给予皮下注射5、10、20和40μg·kg-1·d-1rhVTH(1-34)治疗8周。观察骨量、骨生物力学、骨形态计量及骨代谢相关血尿生化指标,综合评价PTH对糖皮质激素诱发OP的治疗效果。结果显示肌注地塞米松大鼠的骨量、骨生物力学较对照组显著性下降,表明诱导大鼠骨质疏松模型成立。不同剂量咖治疗均能显著增加模型大鼠的腰椎与股骨骨密度、股骨干重与灰重,提高股骨三点弯曲最大载荷、提高腰椎骨小梁面积百分比及矿化沉积率(P<0.05-0.001),并呈一定剂量效应关系。血钙、磷无明显变化。结论外源性PTH对糖皮质激素诱发的大鼠OP具有显著治疗作用。     

雌激素及雄激素对去睾丸大鼠骨质疏松 形成的干预研究

目的　研究雌、雄激素对去睾丸大鼠腰椎、股骨颈、粗隆部、股骨近端的骨密度及股骨颈骨微结构的变化。方法　选用 39只 3～ 4月龄的Wistar雄性大鼠 ,随机分成假去睾丸组 (Sham)、去睾丸组 (Orch)、去睾丸 +雌激素组 (Orch +E2 )和去睾丸 +雄激素组 (Orch +T) ,同条件下饲养 1 8w。处死前用HologicQDR 2 0 0 0 +DEXA测量大鼠腰椎、股骨颈、粗隆部、股骨近端的骨密度。处死前第 1 4 ,1 3d和第 3 ,2d行骨荧光标记 ,大鼠处死时收集血清行T和E2 放免检测 ,同时取左侧股骨近端行塑料包埋的骨组织切片及组织形态计量学分析。结果　Orch组大鼠 1 8w后腰椎、股骨颈、粗隆部、股骨近端的骨密度均下降 ,与Sham组比较差异有显著性 (P <0 0 1 )。Orch +E2 组大鼠的 4个部位骨密度均最高 ,但与Sham组比较无差异 ,Orch组股骨颈的骨小梁面积百分率和骨小梁数目与Sham组比较均减少 (P<0 0 1 ) ,骨小梁分离度增加 (P <0 0 1 ) ;Orch +E2 和Orch +T组大鼠的各静态参数维持在Sham组水平 ;Orch组的骨荧光标记周长百分率、骨形成率BFR/BS、BFR/BV和BFR/TV均增加 (P <0 0 1 ) ,代表骨吸收的骨小梁面积破骨细胞数和骨小梁周长破骨细胞数均增加 (P <0 0 1 ) ;Orch +E2 和Orch +T组大鼠的各动态参数维持在Sham组水平。结论　     

rhPTH_((1-34))治疗OVX大鼠骨质疏松延后效应的初步研究

目的观察重组人甲状旁腺激素(134)[rhPTH(134)]对卵巢摘除(OVX)大鼠骨质疏松症的治疗作用及停药后效应。方法应用双侧卵巢摘除方法建立模拟绝经后骨质疏松大鼠模型;给予皮下注射20μgkgdrhPTH(134)治疗8周,观察其骨量、骨生物力学、骨小梁形态计量及骨代谢相关血、尿生化指标,综合评价PTH对模型大鼠的治疗效果;同时观察停药8周后上述指标的变化。结果外源性PTH(134)治疗能显著增加模型大鼠的骨量、骨力学性能,改善骨微结构、增加骨转换。用药组的骨密度、股骨三点弯曲与腰椎压缩最大载荷、腰椎骨小梁百分面积显著高于对照组(P<0.05～0.001);血ALP(P<0.05～0.01)与尿Pyd(P<0.05)保持高水平;PTH停药8周后大鼠股骨与腰椎骨密度、股骨三点弯曲与腰椎压缩最大载荷及腰椎骨小梁百分面积均较停药前显著降低(P<0.05～0.001),但仍显著高于OVX对照组(P<0.05～0.001)。结论外源性PTH(134)可显著增加OVX大鼠的骨量,提高骨力学性能,改善骨微结构,对卵巢摘除诱导的大鼠骨质疏松具有明显治疗作用;停药后出现骨量的快速丢失,骨力学性能下降等变化,但仍显示出其对OVX大鼠骨骼的保护作用。     

司坦唑醇预防维甲酸致大鼠骨损害的作用

目的 利用骨密度、骨生物力学、骨组织形态计量学等方法探讨司坦唑醇对维甲酸致骨损害的预防作用。方法 4月龄的SPF级雌性SD大鼠24只，随机分成正常对照组、维甲酸组、司坦唑醇组。正常对照组给予溶剂对照溶液，维甲酸组给予维甲酸70 mg ?kg-1?d-1，司坦唑醇组给予维甲酸70 mg? kg-1?d-1和司坦唑醇0.5 mg? kg-1?d-1。大鼠每次均按5 ml ?kg-1灌胃给药，连续给药28天。实验结束后取大鼠右侧股骨进行骨密度和生物力学参数测量，取右侧胫骨上段和中段进行骨组织 形态计量学测量。结果 与正常对照组比较，维甲酸组大鼠股骨骨密度降低10. 2% (P <0. 01)，生物力学参数弹性载荷、最大载荷、断裂载荷、刚性系数、弯曲能量分别降低39. 1%、32. 9%、36. 4%、40. 2%、38. 0%( P <0. 01)，胫骨上段松质骨静态参数骨组织总面积、骨小梁面积、骨小梁周长分别降低31. 6%、40. 0%、36. 2% (P <0. 01)，动态参数标记周长百分数(％ L. Pm)、骨形成率(BFR/TV、BFR/ BS、BFR/BV)分别降低57. 1%、69. 9%、62. 0%、65. 8% (P <0.01)。胫骨中段皮质骨静态参数（骨组织总面积、皮质骨面积)和骨外膜动态参数均降低，而骨内膜动态参数增强。与维甲酸组比较，司坦唑醇组股骨弹性载荷、刚性系数、弯曲能量分别增加22. 2%、22. 9%、17. 7%(P <0. 05)，而骨密度、胫骨上段松质骨和中段骨皮质骨组织形态计量学参数均无明显变化。结论 司坦唑醇可部分改善维甲酸所致大鼠骨损害。     

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 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.     

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.     

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.     

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.