新型尿素吸附剂的制备及其对血液中BUN吸附性能分析

首次采用海藻酸锌络合物配位吸附尿素分子,研究了这类络合物在不同条件下对尿素的吸附性能.结果表明海藻酸锌络合物对尿素的吸附主要是通过锌与尿素之间的配位作用进行的.在模拟人体生理介质的水溶液中对尿素的吸附率达74.65±4.71%,对血液中尿素的吸附率达65.25±4.33%.     

急性肾衰动物模型的血液灌流实验研究

用纯种大耳白兔作为实验动物,建立肾衰动物模型.海藻酸锌络合物为吸附剂对动物模型进行血液灌流实验,观察该吸附剂血液灌流清除体内脲分子的功效,以及对血液相容性、肝功能、肾功能等临床生化指标的影响.经动物血液灌流对血液中Bun、Cr的清除率达60%以上,而且具有良好的血液相容性.     

血液灌流清除体内免疫复合物的实验研究

本文从5种亲和吸剂（Affinity Absorbent,AA)中筛选出对病理性循环免疫复合物（Cycle Immune Complex,CIC)具有特异性吸附的吸附剂AA3，测定其孔结构参数，讨论了不同吸附条件对吸附性能的影响。用纯种大白兔作为实验动物，建立高特环免疫动物模型，用AA3吸附剂对运动模型进行血液灌流实验，观察该吸附剂血灌流清除血中CIC的功效。考察了AA3吸附剂的血液相容性及对蛋白的影响。实验结果表明AA3吸附剂对血中CIC的吸附率达41.７％，动物模型血灌流对ＣＩＣ的吸附率达３８.4%。     

固定多粘菌素B的新型吸附剂对血液中细菌内毒素吸附性能的实验研究

研究了固定有多粘菌素B（Polymyxin B,PMB）短肽的聚苯乙烯微球对血浆中细菌内毒素的亲和吸附性能，讨论了不同吸附条件对吸附性能的影响。用纯种大白鼠作为实验动物，建立内毒索血症动物模型。用固定有PMB短肽的聚苯乙烯微球对动物模型进行血液灌流实验，观察该吸附剂血液灌流清除血浆中内毒素的功效，考察了接有PMB短肽的聚苯乙烯微球的血液相容性及其对蛋白的影响。实验结果表明。采用血液灌流吸附疗法成功地清除动物模型血液中的内毒素，而且，固定有多粘菌素B的特异吸附剂具有良好的血液相容性。     

亲和吸附剂实验动物(兔)血液灌流清除血中循环免疫复合物的实验研究Ⅱ

介绍了用纯种大耳白兔作为实验动物,建立高循环免疫复合物动物模型,并采用ＡＡ３ 吸附剂对动物模型进行模拟体外血液灌流实验,观察该吸附剂血液灌流清除体内的循环免疫复合物（ＣＩＣ）的功效,观察ＡＡ３ 吸附剂的血液相容性及对蛋白的影响。     

亲和吸附剂实验动物（兔）血液灌流清除血中循环免疫复合物 …

介绍了用纯种大耳白兔作为实验动物,建立高循环免疫复合物动物模型,并采用ＡＡ３吸附剂对动物模型进行模拟体外血液灌流实验,观察该吸附剂血液灌流清除体内的循环免疫复合物（ＣＩＣ）的功效,观察ＡＡ３吸附剂的血液相容性及对蛋白的影响。     

类风湿因子免疫吸附血液灌流材料的制备及其性能评价

制备一种新型的类风湿因子（RF）免疫吸附剂并研究其性能。通过在氯甲基聚苯乙烯-二乙烯树脂（氯球）的表面接枝苯丙氨酸（PHE）,制备出可供临床应用的类风湿因子血液灌流吸附剂（PS-PHE）;体外动态灌流实验测定吸附剂的吸附率;体外动态洗脱实验测定RF的脱落量及脱落率;通过体外灌流模拟实验,检测灌流对血液成分的影响来评价吸附剂的选择性;体外凝血酶原时间（PTs）及凝血酶时间（TTs）检测实验验证材料的血液相容性。免疫吸附剂对类风湿因子IgA RF、IgG RF、IgM RF的吸附率分别可以达到45.21%±1.80%、56.02%±1.36%、52.40%±2.01% (n=5),洗脱后脱落率分别为22.10%±1.65%、19.23%±1.06%、21.31%±1.35% (n=5)。全血灌流实验中材料对红细胞、血小板、总蛋白的吸附均在10%以下。同时体外凝血酶原时间（PTs）及凝血酶时间（TTs）测定结果显示PS-PHE能延缓凝血速度。结论PS-PHE对RF具有较高的吸附率及特异性并且表现出优良的血液相容性,在类风湿关节炎的临床治疗方面具有良好的应用前景。     

琼脂凝胶键连热聚IgG——一种新型类风湿关节炎免疫吸附剂

将热聚IgG固载到琼脂凝胶珠上 ,制成了一种特异性类风湿关节炎免疫吸附剂。体外吸附实验表明该吸附剂对类风湿因子及其免疫复合物具有强的选择吸附性能 ,活体动物全血灌流实验证明该吸附剂具有良好的血液相容性和机械强度     

DAC包囊树脂血液灌流对阿霉素的吸附研究

本文探讨二乙酰化甲壳素包囊树脂(DAC包囊树脂)血液灌流对阿霉素的清除作用。实验分为体内及体外两部分。体外动态吸附试验比较了包括DAC包囊树脂在内的四种吸附剂对阿霉素的吸附性能,结果显示DAC包囊树脂吸附效果最佳。体内实验资料同样显示DAC包囊树脂对阿霉素的良好吸附性,大鼠经肠系膜静脉一次性注射阿霉素(5mg/kg)后。在血液流速为1ml/min的灌流条件下,经吸附2、30、60 min时,其阿霉素的廓清率分别达0.99、0.82、0.73 ml/mim。     

功能基化天然生物多糖吸附剂制备及对血浆胆红素的清除

背景:目前临床上应用的血液/血浆灌流吸附剂主要为活性炭和化学合成高分子大孔树脂。活性炭微末会造成栓塞,树脂致孔剂多为甲苯类溶剂不易洗脱干净引起不良反应。用天然高分子材料修饰交联制备吸附剂意义重大。目的:用天然生物多糖-壳聚糖作为胆红素吸附剂的骨架基质,经胺化修饰交联,以蔗糖为致孔剂制备功能基化交联壳聚糖吸附剂,比较该吸附剂与市售BL-300型血浆灌流吸附剂对血浆胆红素吸附性能。方法:用功能基化交联壳聚糖吸附剂和市售BL-300型血浆灌流吸附剂,分别对高胆红素血浆进行灌流吸附试验,全自动生化分析仪测定不同吸附剂对血浆胆红素的吸附率。结果与结论:功能基化交联壳聚糖吸附剂和市售BL-300吸附剂对不同浓度的胆红素血浆均具有良好的吸附效果,功能基化交联壳聚糖吸附剂对胆红素的吸附率可达50.2%,BL-300吸附剂对胆红素的吸附率可达56.8%,与文献报道基本一致。结果证实,功能基化交联壳聚糖吸附剂血浆灌流清除胆红素效果明显且安全可靠,有望作为生物医用血浆灌流材料。     

稳定表达UT-A2的FRT细胞系的建立与鉴定

目的：建立稳定表达尿素通道蛋白A2（UT—A2）的FRT细胞系，为寻找UT—A2抑制剂提供细胞模型。方法：通过真核表达质粒-脂质体介导的方法，将UT—A2 cDNA与真核表达载体pUB6／V5连接后的重组质粒转染入FRT细胞，经稳定筛选建立稳定表达UT—A2的FRT细胞系。功能检测实验将细胞分为对照组和稳定转染组，用2mol／L尿素负荷试验检测稳定表达UT—A2的FRT细胞膜的尿素通透性。结果：经BSD筛选21d后得到稳定表达UT—A2的细胞株；Western blotting证实UT—A2蛋白稳定表达；免疫荧光分析结果提示UT—A2的质膜定位。2mol／L尿素试验证实了该细胞系具有明显尿素通透性。结论：在非肾脏上皮细胞获得了稳定质膜定位表达UT—A2的FRT细胞株，该细胞株可用于UT—A2抑制剂的筛选。     

AQP3 缺失小鼠尿素和尿浓缩能力的研究

目的： 肾脏表达水通道蛋白3（AQP3）在尿浓缩机制中起着极其重要的作用。AQP3缺失小鼠表现为尿浓缩功能严重障碍。为阐明这种基因缺失的生理特性和发生机制,我们利用AQP3基因敲除小鼠和野生型小鼠复制急性尿素负荷动物模型,对其作用机制及影响进行研究。方法: 对小鼠实施急性尿素负荷,从实验前2 h到尿素负荷后第8 h,每隔2 h收集1次尿样分别检测尿量、尿渗透压及尿素浓度。分离肾脏组织RNA进行实时荧光定量RT-PCR反应。应用Western blotting分析肾组织中尿素转运蛋白（UTs）的变化。结果: 给予尿素后4 h左右,2种不同基因型小鼠均有负荷尿素的排泄。尿素负荷后AQP3缺失小鼠尿的渗透压和尿素含量逐渐增高,第 8 h,几乎与野生型小鼠值相等,但尿中非尿素溶质浓度却没有改变。在最后4 h内尿量下降到基础值的1/4。AQP3基因缺失和野生型小鼠尿素负荷显著地上调了UT-A3的表达。结论: AQP3基因缺失并没有直接干扰肾脏对尿素的浓缩功能,但却减弱了对尿中其它溶质浓缩的能力。这种对溶质选择性的反应是由于AQP3对水和尿素转运能力的不同所致。结果表明AQP3对尿中非尿素溶质的浓缩具有特殊作用。     

Urea handling by the medullary collecting duct of the rat kidney during hydropenia and urea infusion

Previous micropuncture studies of distal tubule fluid and ureteral urine have indicated a varying degree of urea reabsorption in the collecting duct. In the present experiments the microcatheterization technique was used to directly determine urea, Na, K, total solute and fluid reabsorption along the length of the medullary collecting duct in anaesthetized hydropenic rats and in rats given low dose urea infusion (P_urea 18.9 mM/l). In hydropenic rats, the remaining fraction of filtered urea did not change significantly along the collecting duct, as indicated both by regression analysis of all samples and by comparison of paired samples from the corticomedullary junction and papillary tip. During low dose urea infusion, urine osmolality increased in proportion to the increase in urea concentration and again there was no net urea reabsorption between the beginning and end of the duct. However, during urea infusion, analysis of samples from the beginning, mid-zone, and end of the collecting duct indicated that urea entry occurred in the proximal portion of the duct (beginning to mid-zone,P<0.01) and that urea reabsorption occurred in the distal portion (mid-zone to end,P<0.01). The lack of significant net urea reabsorption along the duct despite the excretion of moderately concentrated urine, has implicatios for the concept of medullary urea recycling and for models of the urinary concentrating mechanism. The finding of functional heterogeneity with respect to urea handling in the collecting duct in vivo, with both reabsorption and secretion being demonstrated, raises the possibility that internal recycling of urea in the medullary collecting duct itself may contribute to maintenance of a high papillary interstitial urea concentration.     

Urea reabsorption in the medullary collecting duct of protein-depleted young rats before and after urea infusion

The aims of the present study were to examine urea handling along the length of the medullary collecting duct (MCD) in protein-depleted young rats and to determine the effect of urea infusion on MCD function and urine concentrating ability. In 10 young rats on a low protein diet, urea reabsorption equivalent to 18.3% of the filtered load was observed along the MCD (4.5 mm) using the microcatheterization technique. Collecting duct urea reabsorption occurred almost entirely (16.6%) in the distal portion of the MCD (mid-zone to papillary tip, 2.8 mm). These results are in contrast to the lack of net urea reabsorption along the MCD in protein-replete adult rats [21]. After urea infusion which raised plasma urea level from 3.5 to 10.5 mmol/l in protein-depleted rats, urine non-urea solute concentration increased in the non-exposed right kidney from 827 to 1,199 mosm kg^–1 (P<0.001) but the increase was not significant in the experimental left kidney (590 to 619 mosm kg^–1). Thus exposure of the papilla interfered with urea-induced enhancement of urine concentrating ability. After urea infusion, fractional urea reabsorption in the distal portion of the MCD was similar to that before infusion (21.1%) of filtered load) but the absolute load of urea delivered to the MCD and reabsorbed along the duct was markedly increased (2.7-fold). In 6 rats with an increase in urine non-urea solute concentration in the experimental kidney after urea infusion, fluid reabsorption along the duct was significantly increased. The results indicate that in protein-depleted young rats (1) there is significant urea reabsorption in the distal portion of the medullary collecting duct, (2) urea infusion contributes to enhanced urine concentrating ability, in part, by increasing absolute urea reabsorption and also water reabsorption in the collecting duct.     

The adaptation of renal urea excretion after unilateral nephrectomy and after overloading with urea

Summary Urea and inulin clearances were measured in unanesthetized rats 5 and 50 h, and 2–3 weeks after unilateral nephrectomy. At identical i-v infusion rates, urine flow in the uninephrectomized animals was similar to that of sham-operated controls. In the low range of urine flow rates, fractional urea excretion was higher in recently uninephrectomized animals than in controls. The increase appeared to be the consequence of the increased fractional excretion of water. At higher rates of urine flow, and after large loads of urea, the single kidney excreted urea in a manner similar to that of control kidneys. Urea clearances were, in 148/150 clearance determinations, lower than the simultaneously measured inulin clearances. A large increase of GFR was observed in rats chronically loaded and acutely infused with urea.Supported by Fonds National Suisse de la Recherche Scientifique, Grant No. 3440.70.     

Whole body urea kinetics

Improved methods are needed for dose quantification in dialysis because the kinetic modelling based on blood side urea concentrations, as currently used, is subject to several theoretical and practical problems. Since the treatment induces a disequilibrium, it is necessary to make assumptions about the distribution and exchange of urea within the body. A new method is presented which avoids these problems. The amount of urea removed is determined from continuous measurements in the spent dialysate. It is shown that the relative dialysis efficiency K/V can be calculated from the mass removal rate in relation to the mass remaining in the body, which is also determined from the measurements. As a by-product the total mass of urea in the body before the treatment is obtained. This can be used together with the blood concentration to calculate the urea distribution volume, which might be used as an additional clinical parameter. The new method was tested in three in vitro treatments of a container with a known amount of urea added to a known volume of dialysate. The calculated dose KT/V and initial urea mass differed from the true values by less than 3%.     

The relation between the reabsorption of urea and of water in the distal tubule of the rat kidney

Summary Micropuncture studies on rats with hereditary hypophysial diabetes insipidus were undertaken to examine the effects of water and osmotic diuresis and dietary protein on renal tubular urea handling.The results show that in a massive water diuresis the urea present at end of the proximal tubules is practically quantitatively exreted in the final urine. In osmotic diuresis an ever increasing amount of urea reaches the end of the proximal tubule, sinceTF/P _urea of 1.31±0.16 in water diuresis remains constant in osmotic diuresis, whilstTF/P _inulin falls from 2.41±0.21 in water diuresis to values lower than 2.00 in osmotic diuresis. In this case fractional amounts of urea of the same order as in the proximal tubule were measured in the distal convolution and in the final urine. A value of 0.99±0.17×10^–4 mm/sec for the distal tubular urea permeability was obtained by direct measurement at high plasma and high intratubular urea concentrations and did not change significantly after pretreatment on low or high protein diet (1.00±0.20 and 1.05±0.23×10^–4 mm/sec, respectively). From these results we conclude: 1. The magnitude of the urea excretion in a massive diuresis is primarily determined by the water reabsorption in the distal nephron. 2. The urea permeability of the distal convolution is independent of the concentration thus excluding the suggested possibility that there exists a reabsorption mechanism for urea autonomous of water reabsorption. 3. The fall in fractional urea excretion in animals on low protein diet is due entirely to mechanisms located in the collecting duct.Supported by the Deutsche Forschungsgemeinschaft.     

Positive regulatory elements involved in urea amidolyase and urea uptake induction in Saccharomyces cerevisiae

Summary Urea amidolyase and the high affinity urea uptake system are induced by allophanate. durM ^– and durL ^– recessive mutations, which are easily obtained, totally prevent this induction. They are not linked to each other nor to the concerned structural genes. Despite an intensive hunt, no mutation of repressor or classical operator type has been selected. We conclude that urea amidolyase and urea uptake induction involves at least two positive elements coded for by the durM and durL genes.     

Phloretin sensitive active urea absorption in frog skin

This report presents evidence for urea active absorption by isolated skin of Rana esculenta. One of the supporting factors of such evidence is that at a low concentration the urea influx is five times greater than the outflux, in the absence of a chemical gradient.The transport shows a saturation kinetics with an apparentK _m =1.33mM and is inhibited by an uncoupling agent (ECCP).5·10^–4M Phloretin, added to the external side, markedly inhibits inward urea transport, whereas it is ineffective when added to the serosal fluid. This provides evidence for a phloretin-sensitive mechanism located at the external side of the epithelium. Phloretin stimulates the sodium active transport; the possible coupling of urea and sodium movement is analysed