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KT/Vurea和Ccr是否适合作为腹膜透析充分性指标的理论探讨 总被引:1,自引:0,他引:1
腹膜透析中用作透析充分性的指标主要有尿素清除指数(KT/Vurea)和肌酐清除率(Ccr)。为了探讨这两个指标是否能够全面准确地反映腹膜透析充分性,我们依据三孔模型的理论建立物质跨腹膜转运的数学模型,描述了单次透析过程中水和溶质在透析液中的浓度和总量随时间的变化规律。我们发现,分子量不同的溶质清除速率和清除总量并不一定存在相关关系;尿素和水钠的清除量之间有本质的区别。尿素、肌酐的清除既不能代表大、中分子的清除,也不能代表水盐的清除。因此,KT/Vurea和Ccr可能不适合单独用来评价腹膜透析充分性。 相似文献
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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。 相似文献
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陆茉珠 《国际生物医学工程杂志》1988,(2)
用于人工肾系统高容量选择性吸附尿素的吸附剂至今没有研制成功。为此,作者利用悬浮聚合的方法合成了三种共聚物作为尿素吸附剂。在pH=.0~7.4,浓度为130mg%的尿素磷酸氢钠缓冲液中,于37℃下进行体外吸附实验,结果表明吸附量不低于40mg/g。实验还发现尿素吸附量与吸附剂的比表面、吸附温度、吸附时间、尿素浓度、溶液的pH值等条件有关。在实验范围内,温度提高有利吸附;10小时活吸附趋于平衡;随pH值的提高吸附能力迅速下降。为了观察吸附剂能否用于临床,作者对透析废液中尿素用新制备的尿素吸附剂 相似文献
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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。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尿素的功效 ,以及对肝功能、肾功能等临床生化指标的影响。在模拟人体生理介质的水溶液中对尿素吸附率达 74 .6 5± 4 .71%。对血液中尿素的吸附率达 6 5 .2 5± 4 .33%。经动物血液灌流对血液中Bun、Cr的清除率达 6 0 %以上。 相似文献
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观察作者自制的尿素免疫脂质体对体外培养的人血管瘤内皮细胞(HVEC)的作用和影响.通过尿素免疫脂质体对体外培养的HVEC形态学影响的观察、细胞毒测定、和对群体倍增时间的影响研究.结果表明:加入尿素免疫脂质体后,HVEC细胞状态差,细胞有皱缩且随浓度的增高抑制明显增强,大于400mg/ml,细胞即刻固定,死亡;随着尿素免疫脂质体终浓度的逐渐升高和作用时间的延长,HVEC细胞存活率逐渐降低,与对照组相比有显著性差异,呈明显的剂量和时间依赖性.HVEC细胞存活率与尿素免疫脂质体终浓度呈显著负相关,相关系数为-0.97315,(P<0.01);2.6%尿素组的细胞杀伤率为27.94%.2.6%尿素脂质体组的细胞杀伤率为84.01%.2.6%尿素免疫脂质体组的细胞杀伤率为99.91%.说明尿素免疫脂质体对体外培养的HVEC具有明显的抑制和杀伤作用. 相似文献
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目的 研究荧光光谱法检测癌光啉在BN大鼠体内的药代动力学.方法 BN大鼠尾静脉注射5 mg/kg体质量的癌光啉,于给药后的10 min、30 min、1h、2h、4h、8h、24 h、48 h和72 h眼眶后静脉丛取血,以荧光光谱仪测定大鼠血浆中癌光啉浓度,用DNS2.0处理血药浓度-时间数据,分析房室模型,得到最佳房室模型和药代动力学参数.结果 BN大鼠静脉注射的时量曲线符合三室模型.主要药代动力学参数:t1/2a=0.096 h,t1/2β=1.299 h,t1/2=19.387 h,V1=0.259 L/kg,A UC=15.263 mg/(L·h).结论 荧光光谱法检测光敏剂血药浓度操作简单,耗时短,灵敏度和特异性高.癌光啉在BN大鼠体内吸收快,起效快,无蓄积现象. 相似文献
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顾汉卿 《国际生物医学工程杂志》1988,(2)
连读不卧床腹膜透析是近期发展较快的一种透析技术,它可以利用增加透析液中溶质、加大透析液与血液之间的静水压力差来进行水的超滤,由于扩散作用,溶质从透析液进入血液,从而使超滤速率在整个腹膜透析过程中逐渐下降。因此,如何维持透析液的渗透压是极其重要的一个问题。作者从体内细胞内室与细胞外室体内代谢物浓度均一的观点出发,利用单池模型研究了连续不卧床腹膜透析期间透析液体积和葡萄糖浓度的经时变化。利用该模型无须假设直接计算超滤速率。结果表明,在腹膜透析期间超滤的体积决定于腹膜的渗透特性和葡萄 相似文献
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Urea transport by cotransporters 总被引:7,自引:3,他引:4
Daisy W. Leung Donald D. F. Loo Bruce A. Hirayama Thomas Zeuthen Ernest M. Wright 《The Journal of physiology》2000,528(2):251-257
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Urea excretion in mammals 总被引:4,自引:0,他引:4
SCHMIDT-NIELSEN B 《Physiological reviews》1958,38(2):139-168
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H. Kaess 《Journal of molecular medicine (Berlin, Germany)》1970,48(20):1245-1246
Summary In the basal secretion and in the gastric juice after stimulation with 6 µg/kg Pentagastrin in 15 persons a linear reciprocal relationship (r=–0.84) between the concentration of H+ and urea was demonstrated. The urea concentration in the non parietal secretion was 32 mg%, which corresponded to the serum urea concentration of 29 mg%. The interception of the dose relationship line was at a H+ concentration of 148 mEq/L. From this data it is concluded that urea is not secreted in the parietal secretion, but is excreted in the non parietal secretion in the same concentration as in the extracellular fluid.
Zusammenfassung Eine umgekehrte lineare Beziehung zwischen den Konzentrationen von H+ und Harnstoff (r=–0,84) konnte in der Nüchternsekretion und der Magensaftsekretion nach Stimulierung mit 6 µg/kg Pentagastrin von 15 Personen nachgewiesen werden. Die Harnstoffkonzentration in der alkalischen Primärsekretion stimmte mit 32 mg% gut mit der Serumharnstoffkonzentration von 29 mg% überein. Der Schnittpunkt der Regressionsgeraden lag bei einer HCl-Konzentration von 148 mval/l. Diese Befunde zeigen, daß Harnstoff nicht in der sauren Primärsekretion, sondern in der alkalischen Primärsekretion mit derselben Konzentration wie im Extracellulärraum sezerniert wird.相似文献
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One representative of each of five different pathogenic serotypes of Leptospira as well as one saprophytic strain were capable of growing on medium containing urea in place of an ammonium salt as a nitrogen source. Growth of all of the organisms tested on 1% urea was substantial, but only those that exhibited strong urease activity could grow to any appreciable extent on urea at a concentration as high as 2%. Intact urea-grown cells of the pathogenic serotypes tested (grippotyphosa and icterohaemorrhagiae) exhibited urease activity, with the level of activity of the former being considerably greater. No urease could be detected in cells of the saprophytic strain. When the pathogenic leptospires were sonicated or treated with toluene, the urease activity was greatly enhanced. When cultivated on NH(4)Cl, neither intact nor disrupted cells of any of the strains tested exhibited any urease activity. Cells of the grippotyphosa and icterohaemorrhagiae strains exhibited diauxic growth when cultivated in the presence of both NH(4)Cl and urea, whereas only monophasic growth could be detected for the saprophytic test strain. The experimental data on urea utilization and urease activity, when considered in the light of previously reported findings on leptospiral pathology, renal physiology, and the role of urease in other bacterial infections, suggests a significant role for leptospiral urease (in addition to other factors) in determining localization of the organism in the kidney and contributing to the resultant kidney pathology. 相似文献
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S. I. Pisarenko E. B. Minkovskii I. M. Studneva 《Bulletin of experimental biology and medicine》1980,89(2):138-141
Urea formation by the isolated rat heart was studied during perfusion with NH4Cl (10 mM), mixtures of NH4Cl (10 mM) and L-aspartic acid (10 mM) and L-ornithine (2.5 mM) with L-arginine (10 mM), L-glutamine (10 mM), L-alanine (10 mM), L-leucine (5 mM), and pyruvate (5 mM). The most effective activator of urea synthesis is NH4Cl and L-arginine; L-leucine and pyruvate have an inhibitory action. It was shown with the aid of the isotope15N that ammonia fixation can take place in the heart tissue through the formation of urea. The quantity of15N incorporated into urea increases with an increase in the concentration of ammonium-15N acetate in the perfusion fluid from 1.6 to 3.4 mM. Isoproterenol necrosis of heart muscle leads to a significant increase in15N incorporation into urea.All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR E. I. Chazov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 165–168, February, 1980. 相似文献
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Urea transport in elasmobranch erythrocytes 总被引:2,自引:0,他引:2
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