Investigations on the adsorbents for uremic middle molecular toxins (II)

Chitosan resins, which clinically served as adsorbents in hemo perfusion therapy, were prepared with reversed-phase suspension methodology using three differently structured crosslinking agents, methanal, glyoxal and glutaraldehyde. And the glyoxal and glutaraldehyde crosslinked chitosan resins were reduced with NaBH₄ afterwards. By analyzing the results from FTIR and SEM, it was found that the reduction treatment to the adsorbents efficiently improved the chemical stability of these chitosan resins, and the shifts in crosslinking agents exerted influences over the morphologies of the adsorbents obviously. After being put to use in the adsorption tests upon some model uremic middle molecular toxins and BSA in vitro, all three adsorbents demonstrated a fairly realistic adsorption capability to the model toxins but little to BSA. And the adsorption process reached the equilibrium in a clinically qualified short time. But the adsorption capacities of these adsorbents to the model toxins were quite different. It had been found that with the growing of fatty chain length of crosslinking agent, these adsorbents showed a gradually increased adsorption capacity to the model toxins, and the glutaraldehyde crosslinked chitosan resin behaved best.     

Investigations on the adsorbents for uremic middle molecular toxins (Ⅱ)——Influences of crosslinking agent chain length on the adsorption capacities of crosslinked chitosan adsorbents

Chitosan resins, which clinically served as adsorbents in hemoperfusion therapy, were prepared with reversed-phase suspension methodology using three differently structured crosslinking agents, methanal, glyoxal and glutaraldehyde. And the glyoxal and glutaraldehyde crosslinked chitosan resins were reduced with NaBH4 afterwards. By analyzing the results from FTIR and SEM, it was found that the reduction treatment to the adsorbents efficiently improved the chemical stability of these chitosan resins, and the shifts in crosslinking agents exerted influences over the morphologies of the adsorbents obviously. After being put to use in the adsorption tests upon some model uremic middle molecular toxins and BSA in vitro, all three adsorbents demonstrated a fairly realistic adsorption capability to the model toxins but little to BSA. And the adsorption process reached the equilibrium in a clinically qualified short time. But the adsorption capacities of these adsorbents to the model toxins were quite different. It     

Anti-hyperuricemia activity and toxicity prediction of a novel xanthine oxidoreductase inhibitor

A potent xanthine oxidoreductase inhibitor (LS087) was recently proved to exhibit a similar hypouricemic potency to febuxostat. A hyperuricemia model induced by potassium oxonate and hypoxanthine was proposed in specific pathogen-free male Kunming mice, and the serum urea nitrogen, creatinine and uric acid levels were measured after oral administration of LS087. Furthermore, renal histopathology was conducted by staining with hematoxylin and eosin, periodic acid–Schiff and Masson's trichrome stains, respectively. The results showed that the levels of serum urea nitrogen and uric acid significantly decreased compared with the model group, but the level of creatinine showed no significant changes. The pathological abnormalities in kidney tubules were improved after LS087 administration. Ten metabolites (M1–M10) of LS087 were identified after a single oral dosing of 10 mg/kg in rats. M6 was the primary LS087 metabolite in vivo with a pathway of methylation. The toxicity and potential risks of LS087 and its metabolites were predicted using the ProTox-II software. LS087 and the major metabolites (M2, M3, M5, M6, M7 and M8) were predicted to have no potential hepatotoxicity, but some metabolites with a total rate of <1% (M1, M4, M9, and M10) showed potential hepatotoxicity. M1 and M8 showed potential carcinogenicity. The LS087 biotransformation pathway in rat was well characterized.     

Separation of urea, uric acid, creatine, and creatinine by micellar electrokinetic capillary chromatography with sodium cholate

The capillary electrophoretic separation of the four nonprotein nitrogenous compounds (NPNs; urea, uric acid, creatine, and creatinine) typically employed in clinical and medical settings for the monitoring of renal function is described. Successful resolution of these compounds is achieved with the use of a bile salt micelle system composed of sodium cholate at phosphate buffer pH 7.4. The elution patterns of four NPNs are obtained within 30 min with a voltage of 30 kV. The effect of varying the applied voltage, temperature, and the mole ratio of phosphate buffer with bile salt surfactant on the migration behavior is also examined.     

慢性肾衰患者血清中分子物质浓度变化及其对Na,K-ATP酶的抑制作用

慢性肾功能衰竭是指在各种慢性肾脏疾病的基础上,缓慢出现肾功能减退而不可逆转的肾衰竭综合症由于患者肾功能衰竭,使得一些正常人本可以排出体外的代谢产物滞留在体内,导致肌体的一系列病变,涉及到人体的肠胃、免疫、心血管、内分泌、皮肤和骨骼等各个系统．20世纪70年代以来,中分子物质在患者体内的毒性作用开始引起众多研究者的关注．然而,由于这类物质成分复杂,对其分离鉴定工作还面临着很多困难,它们与慢性肾衰患者的临床症状之间的因果关系及致病机理仍不甚明确．在前期研究中,我们采用凝胶色谱法分离尿毒症患者血清,得到两个中分子物质峰A和B,     

Present status of hemoperfusion/hemodialysis in Italy

The use of charcoal hemoperfusion in the treatment of chronic renal failure has been proposed and applied by several authors. The availability of coating membranes of increased biocompatibility currently allows a safer and wider use of this purifying technique. It has been recently demonstrated that long-term treatment with combined hemodialysis/hemoperfusion yields an improvement of certain dialysis-resistant uremic signs in patients on regular dialysis treatment, while in selected patients it affords a marked reduction (up to one-third) in the overall time of treatment per week. The tolerance of long-term treatment is good. In line with these findings, a multicenter study has been carried out in Italy with two main aims: (1) to see whether long-term treatment with charcoal hemoperfusion is really safe and substantially free from side effects; (2) to verify in a larger and more varied population of patients whether such long-term treatment actually improves certain uremic signs persisting despite adequate dialysis treatment. A third phase of the multicentric study (reducing the weekly time of treatment) is currently being worked on. Five nephrology and dialysis departments took part in the study: in Bologna, Rome, Chieti, Ancona, and Lecce.     

Some aspects of quantification of neutral steroid metabolites in body fluids of healthy and uremic subjects by capillary gas chromatography

Neutral steroid metabolites enriched from urine and hemofiltrate were identified by gas chromatography/mass spectrometry and quantified by capillary gas chromatography. This study included 20 healthy controls and 37 uremic patients. Before enrichment of steroids from biological material, the standard deviation of the workup procedure and subsequent derivatization into the trimethylsilyl-enol-trimethylsilyl ethers was tested and found to be 2–5% in urine and 12–17% in the more complicated workup procedure of hemofiltrate, but essentially smaller than the biological standard deviation. Compared to the 24 h urinary excretion rates of controls, the excretion rates of androsterone, etiocholanolone, and corticoid metabolites were significantly lower in uremic body fluids, while those of 11-oxygenated androstanolones, degradation products of corticoids, were enhanced in uremic urine. The ratio of corticoid metabolites to 11-oxygenated androstanolones in urine of nondialyzed uremics correlated significantly with their plasma creatinine levels.     

A computational strategy for metabolic network construction based on the overlapping ratio: Study of patients’ metabolic responses to different dialysis patterns

BackgroundUremia is a worldwide epidemic disease and poses a serious threat to human health. Both maintenance hemodialysis (HD) and maintenance high flux hemodialysis (HFD) are common treatments for uremia and are generally used in clinical applications. In-depth exploration of patients’ metabolic responses to different dialysis patterns can facilitate the understanding of pathological alterations associated with uremia and the effects of different dialysis methods on uremia, which may be used for future personalized therapy. However, due to variations of multiple factors (i.e., genetic, epigenetic and environment) in the process of disease treatments, identification of the similarities and differences in plasma metabolite changes in uremic patients in response to HD and HFD remains challenging.MethodsIn this study, a computational strategy for metabolic network construction based on the overlapping ratio (MNC-OR) was proposed for disease treatment effect research. In MNC-OR, the overlapping ratio was introduced to measure metabolic reactions and to construct metabolic networks for analysis of different treatment options. Then, MNC-OR was employed to analyze HD-pattern-dependent changes in plasma metabolites to explore the pathological alterations associated with uremia and the effectiveness of different dialysis patterns (i.e., HD and HFD) on uremia. Based on the networks constructed by MNC-OR, two network analysis techniques, namely, similarity analysis and difference analysis of network topology, were used to find the similarity and differences in metabolic signals in patients under treatment with either HD or HFD, which can facilitate the understanding of pathological alterations associated with uremia and provide the guidance for personalized dialysis therapy.ResultsSimilarity analysis of network topology suggested that abnormal energy metabolism, gut metabolism and pyrimidine metabolism might occur in uremic patients, and maintenance of both HFD and HD therapies have beneficial effects on uremia. Then, difference analysis of network topology was employed to extract the crucial information related to HD-pattern-dependent changes in plasma metabolites. Experimental results indicated that the amino acid metabolism was closer to the normal status in HFD-treated patients; however, in HD-treated patients, the ability of antioxidation showed greater reduction, and the protein O-GlcNAcylation level was higher. Our findings demonstrate the potential of MNC-OR for explaining the metabolic similarities and differences of patients in response to different dialysis methods, thereby contributing to the guidance of personalized dialysis therapy.     

Derivatization of Methylamine and Ethylamine Followed by LC and Fluorescence Detection for Measurement of Urinary Clearance

Monomethylamine (MMA) and ethylamine (EtA) accumulate in uremia. However, the urinary clearances of these compounds in normal humans and those with chronic kidney disease (CKD) have not been studied. In this work, an LC based fluorescence assay for MMA and EtA was developed. In applying the method, we found that some previous assays of urinary levels of MMA and EtA lead to overestimations. Normal subjects with average creatinine clearance of 82 ± 21 mL min^?1 demonstrate clearances for the two aliphatic amines less than the creatinine clearance, and in the range of urinary urea clearance. CKD subjects with an average creatinine clearance of 37 ± 12 mL min^?1 had modestly but significantly elevated serum levels of MMA and EtA above normals. Their fractional clearances were increased markedly compared to normals, mitigating the rise in their plasma levels. These findings imply enhanced secretion and/or reduced reabsorption of the amines with CKD.     

Sol-Gel Technique for Production of Spherically Granulated Zirconium(IV) Phosphate

A sol-gel technique for production of spherically granulated zirconium(IV) phosphate of Termoksid-3A brand is described. The method includes the following main stages: electrolysis of a zirconium(IV) chloride solution to give a sol of zirconium(IV) hydroxide, drop dispersion of the sol into an ammonia solution, conversion of gel-spheres of zirconium(IV) hydroxide into zirconium(IV) phosphate, and washing and drying of gel-spheres. The physicochemical and ion-exchange properties of the product obtained were studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 229–234.Original Russian Text Copyright © 2005 by Sharygin, Kalyagina, Borovkov.     

Capillary Electrophoresis as A Diagnostic Tool: Determination of Biological Constituents Present in Urine of Normal and Pathological Individuals

Abstract

A quantitative ultraviolet detection method for the determination of urinary metabolites is described using capillary zone electrophoresis. The determination of these metabolites is simple, fast. reproducible and utilizes very small amounts of sample. This method is linear between 1.0 × 10^?4 and 1.0 × 10^?2 M for creatinine and between 1.0 × 10^?1 and 1.0 M for urea. The ultraviolet method shows detection limits for creatinine in the picogram (femtomol) range, and for urea in the nanogram (picomol) range.     

N-乙酰半胱氨酸保护下给药钆-二乙三胺五乙酸后慢性肾衰大鼠的尿液代谢组学研究

N-乙酰半胱氨酸(NAC)有减轻造影剂引发肾损伤的作用,但其作用机制尚未明确.本研究采用基于1H NMR的代谢组学方法,结合正交偏最小二乘法判别分析(OPLS-DA),在NAC保护下对慢性肾衰大鼠给药造影剂钆-二乙三胺五乙酸(Gd-DTPA), 通过分析大鼠尿液中内源性代谢物的变化,研究了NAC对慢性肾衰大鼠的保护机制.结果表明,慢性肾衰大鼠能量代谢、尿素循环等代谢通路发生紊乱.给药Gd-DTPA后,大鼠尿液中胆碱、N-氧三甲胺、邻羟基苯乙酸苯酯、对羟基苯乙酸苯酯、马尿酸、甘氨酸、烟酸、牛磺酸减少,尿囊素增加;而在NAC保护下相关代谢产物向模型组的恢复,说明NAC对Gd-DTPA引发的大鼠肠道细菌代谢、肝线粒体代谢、犬尿氨酸代谢紊乱及氧化损伤具有一定修复作用.NAC对尿素循环代谢的改善可能减轻大鼠体内的肾损伤,而其对细胞中谷胱甘肽的补充可能减轻Gd-DTPA造成的氧化损伤.     

Preparation and characterization of dual stimuli-responsive microcapsules with a superparamagnetic porous membrane and thermo-responsive gates

A novel dual stimuli-responsive microcapsule with a superparamagnetic porous membrane and linear-grafted poly(N-isopropylacrylamide) (PNIPAM) gates in the membrane pores is successfully prepared and characterized. Oleic acid (OA)-modified Fe₃O₄ nanoparticles are embedded into the polyamide microcapsule membrane during interfacial polymerization process, and then plasma-induced grafting polymerization is used to graft PNIPAM into the pores of microcapsule membranes. The prepared microcapsule membranes exhibit time-independent superparamagnetic property with good magnetic-responsive ability, and satisfactory thermo-responsive controlled-release property due to the thermo-responsive swollen/shrunken property of PNIPAM gates grafted on the inner pore surface of the microcapsule membranes.     

Exploration of novel predictive markers in rat plasma of the early stages of chronic renal failure

To identify blood markers for early stages of chronic kidney disease (CKD), blood samples were collected from rats with adenine-induced CKD over 28 days. Plasma samples were subjected to metabolomic profiling by liquid chromatography-mass spectrometry, followed by multivariate analyses. In addition to already-identified uremic toxins, we found that plasma concentrations of N6-succinyl adenosine, lysophosphatidylethanolamine 20:4, and glycocholic acid were altered, and that these changes during early CKD were more sensitive markers than creatinine concentration, a universal indicator of renal dysfunction. Moreover, the increase in plasma indoxyl sulfate concentration occurred earlier than increases in phenyl sulfate and p-cresol sulfate. These novel metabolites may serve as biomarkers in identifying early stage CKD.     

药用微胶囊的制备

微胶囊技术是21世纪重点研究开发的高新技术之一,用途广泛。本文综述了微胶囊的制备原理及方法,着重阐述了采用超临界二氧化碳技术和溶剂蒸发法制备药物微胶囊的最新研究进展,介绍了超临界流体快速膨胀(RESS)法、超临界流体抗溶剂(SAS)法和气体饱和溶液微粒制备(PGSS)法的特点,总结了溶剂蒸发法制备微胶囊的原理和溶剂蒸发法制备药物微胶囊的工艺研究现状,分析了药物微胶囊的表征方法及性能,并对今后微胶囊技术的发展作了展望。     

Selective adsorption of phosphate from seawater and wastewater by amorphous zirconium hydroxide

Phosphate adsorption from single electrolyte (NaH2PO4), phosphate-enriched seawater, and model wastewater was studied using amorphous zirconium hydroxide, ZrO(OH)2(Na2O)0.05 1.5H2O, as an adsorbent. Batch experiments were carried out to investigate the adsorption of phosphate. The effect of pH on phosphate adsorption from seawater showed that the uptake of phosphate increased with an increase in pH up to 6, and then decreased sharply with a further increase in pH of the solution. The equilibrium data of phosphate adsorption were followed with a Freundlich isotherm. The uptake of phosphate at the adsorbent/solution ratio 0.05 g/2 L was 10 and 17 mg-P/g for the phosphate-enriched seawater and the model wastewater, respectively. A much higher adsorptivity toward phosphate ions in seawater was observed on ZrO(OH)2(Na2O)0.05 1.5H(2)O than on other representative adsorbents based on layered double hydroxides of Mg(II)-Al(III), Mg(II)-Fe(III), and Ni(II)-Fe(III). The effective desorption of phosphate ions on ZrO(OH)2(Na2O)0.05 1.5H2O could be achieved using a 0.1 M NaOH solution. The usefulness of experimental data for practical applications in removing phosphate in seawater and wastewater is discussed.     

Bone fluoride in chronically uremic rats

The whole-body clearance of¹⁸F-fluoride injected intravenously into chronically uremic rats was found to proceed more slowly (7.6% of the dose in the first hour, vs 28%) and to a lesser total amount (18.5% vs 46.7%) in 4 hrs than in normal rats of the same age. The concentration of radiofluoride in the urine of uremies during the first hour was about 10% of that observed in normals. No changes in²⁴Na and⁴²K whole-body clearance rates were detected in this surgically-induced model of chronic uremia. Statistically significant elevations in central compartment fluoride concentrations were observed 4 hrs after injection. Fluorine and calcium in bones of uremic and normal animals were measured using Instrumental Neutron Activation Analysis techniques. The ratios μg F/mg Ca were highly significantly greater in uremics (2.2±0.3 vs 1.1±0.3). These differences were primarily brought about by elevations in bone fluoride rather than by decreases in calcium content of the uremic bone.     

Potentiometric Biosensor System Based on Recombinant Urease and Creatinine Deiminase for Urea and Creatinine Determination in Blood Dialysate and Serum

A biosensor system for simultaneous determination of creatinine and urea in blood serum and dialysate samples was developed. It consisted of creatinine and urea biosensors based on a potentiometric transducers with two identical pH‐sensitive field‐effect transistors. In creatinine biosensor, creatinine deiminase immobilized via photopolymerization in PVA/SbQ polymer on one transistor served as a biorecognition element, while bovine serum albumin in PVA/SbQ polymer placed on the second transistor was used for reference. The urea biosensor was created in the same way but recombinant urease was used instead of creatinine deiminase. The linear ranges of creatinine and urea measurement were 0.02–2 mM and 0.5–15 mM, correspondingly, which allowed simultaneous determination of the metabolites. Response time of the biosensor system was 2–3 min; RSD of responses did not exceeded 5 %. The biosensors demonstrated absence of non‐selective response towards components of blood dialysate and serum. Urea and creatinine concentrations were determined in 20 samples of blood dialysate and serum. The results correlated well with traditional methods of analysis. Creatinine and urea biosensors were stable during five months of storage (during this time the responses decreased by about 10 %). The proposed biosensor system can be effectively used for analysis of serum samples and for hemodialysis control.     

Preparation and release properties of flufiprole-loaded microcapsules with core status of solid particles,solution droplets and oil suspending agent

Our main goal was to evaluate release mechanism of microcapsules with different core status. First, flufiprole microcapsules were directly encapsulated with chitosan (CS) and sodium dodecyl sulfate (SDS) through layer-by-layer (LbL) self-assembly. The changes of process parameters on the microcapsules characteristics (zeta potential, and morphology) were investigated. Also the release trends of flufiprole were determined and fitted with mathematical models. It was revealed that releases of three types of microcapsules were all very similar, but microcapsule with solid particles and oil suspending agent reached their peak values at 36–42, 42–48?h respectively, microcapsule with solution droplets cannot reach a maximum value. In the stage of initial burst release, Higuchi model performed better with oil suspending agent and solid particles, which was in agreement with the Fick's law. Core status being solution, release curves of the pesticide corresponded to zero-order which was in agreement with dissolution mechanism. In the stage of slow release, the values of R² for solution and solid particles were all above 0.98, betokened the release phenomenon were in line with the first-order. On the other hand, release of oil suspending agent conformed to Higuchi model.