Dynamics of Urinary Calprotectin after Renal Ischaemia

Background: Urinary calprotectin has been identified as a promising biomarker for acute kidney injury. To date, however, the time-dependent changes of this parameter during acute kidney injury remain elusive. The aim of the present work was to define the time-course of urinary calprotectin secretion after ischaemia/reperfusion-induced kidney injury in comparison to neutrophil gelatinase—associated lipocalin, thereby monitoring the extent of tubular damage in nephron sparing surgery for kidney tumours. Methods: The study population consisted of 42 patients. Thirty-two patients underwent either open or endoscopic nephron sparing surgery for kidney tumours. During the surgery, the renal arterial pedicle was clamped with a median ischaemic time of 13 minutes (interquartile range, 4.5–20.3 minutes) in 26 patients. Ten retro-peritoneoscopic living donor nephrectomy patients and 6 nephron sparing surgery patients in whom the renal artery was not clamped served as controls. Urinary calprotectin and neutrophil gelatinase—associated lipocalin concentrations were repeatedly measured by enzyme-linked immunosorbent assay and assessed according to renal function parameters. Results: Urinary concentrations of calprotectin and neutrophil gelatinase—associated lipocalin increased significantly after ischaemia/reperfusion injury, whereas concentrations remained unchanged after nephron sparing surgery without ischaemia/reperfusion injury and after kidney donation. Calprotectin and neutrophil gelatinase—associated lipocalin levels were significantly increased 2 and 8 hours, respectively, post-ischaemia. Both proteins reached maximal concentrations after 48 hours, followed by a subsequent persistent decrease. Maximal neutrophil gelatinase—associated lipocalin and calprotectin concentrations were 9-fold and 69-fold higher than their respective baseline values. The glomerular filtration rate was only transiently impaired at the first post-operative day after ischaemia/reperfusion injury (p = 0.049). Conclusion: Calprotectin and neutrophil gelatinase—associated lipocalin can be used to monitor clinical and sub-clinical tubular damage after nephron sparing surgery for kidney tumours. Urinary calprotectin concentrations start rising within 2 hours after ischaemia/reperfusion-induced kidney injury.     

随机尿、晨尿视黄醇结合蛋白对早期肾功能损伤的诊断价值

目的:探究随机尿、晨尿视黄醇结合蛋白对早期肾功能损伤的诊断价值.方法:选取我院2011年8月-2012年9月收治的48例Ⅱ型糖尿病患者,按照随机数字表进行平均分组,随机尿组24例,选取任意时段尿液标本,晨尿组24例,选取清晨时段尿液标本.对两组患者尿液标本进行尿视黄醇结合蛋白(Urinary Retinol-binding Protein,U-RBP)、尿微量白蛋白(Urinary Microalbum, U-mAlb)及尿N-乙酰-β-D氨基葡萄糖苷酶(Urinary N-acetyl beta-D-Glucosaminidase,NAG)水平测定,进行相关性分析并观察两组诊断阳性率.结果:随机尿组U-RBP、U-mAlb及NAG分别为(1.7± 0.9) mg/L、(76.2± 41.5) mg/L及(41.2± 30.0) U/L;晨尿组U-RBP、U-mAlb及NAG分别为(3.6±1.2)mgL、(118.5±71.)mg/L及(116.5±71.9) U/L.两组患者尿液检测指标均高于正常值,且晨尿组指标较随机尿组更高,两组数据对比存在统计学差异;随机尿组U-RBP、U-mAlb及NAG阳性例数分别为12例、6例及4例,晨尿组U-RBP、U-mAlb及NAG阳性例数分别为17例、13例及11例,晨尿组U-RBP、U-mAlb及NAG阳性率均高于随机尿组,两组数据对比存在统计学差异;随机尿组U-RBP与肾损伤相关性r=0.532,P ＞0.05,无明显相关性;晨尿组U-RBP与肾损伤相关性r=0.867,P＜0.01,呈高度正相关.结论:随机尿及晨尿均可指示患者肾损伤出现,但随机尿蛋白指标无法有效指示肾损伤程度,对早期肾功能损害确诊准确率有限,而晨尿尿蛋白正常排泄率更高,且能够有效指示肾损伤程度,适用于糖尿病早期肾功能损伤的诊断及监测.     

Periostin as a Tissue and Urinary Biomarker of Renal Injury in Type 2 Diabetes Mellitus

Background

Improving the early detection of diabetic nephropathy remains a great challenge in disease management. Periostin is a marker of renal tubular injury and related to progressive kidney injury in animal models of chronic kidney disease. The clinical implications of urinary periostin activities in patients with type 2 diabetes have not been evaluated.

Methods

Urine samples were obtained from 30 healthy volunteers and 328 type 2 diabetic patients with normoalbuminuria (n=114), microalbuminuria (n=100) and macroalbuminuria (n=114). The excretion levels of urinary periostin were quantified with enzyme-linked immunosorbent assay. Immunohistochemical periostin expression was determined in kidney tissues from overt diabetic nephropathy.

Results

Increased periostin expression in glomeruli and tubular epithelium in diabetic renal pathology was observed. Urinary periostin levels were significantly elevated in the patients of the normoalbuminuria [3.06 (IQR: 1.12, 6.77) ng/mgCr], microalbuminuria [8.71 (IQR: 5.09, 19.29) ng/mgCr] and macroalbuminuria [13.58 (IQR: 3.99, 16.19) ng/mgCr] compared with healthy controls [1.15 (IQR: 0.60, 1.63) ng/mgCr] (P<0.01).Increased urine periostin level significantly correlated with aging, high albuminuria and decline of GFR. Urine periostin ELISA also demonstrated high performance for the diagnosis of established normoalbuminuric, microalbuminuric and macroalbuminuric type 2 diabetes (AUC 0.78 (95%CI, 0.71 to 0.86), 0.99 (95%CI, 0.98 to 1.00) and 0.95 (95%CI, 0.91 to 0.98), respectively).

Conclusion

The study indicates that increased urine periostin levels can be detected in patients with type 2 diabetes before the onset of significant albuminuria. Urinary periostin is an associated renal derangement in patients with established diabetic nephropathy and it may be used as an early marker of diabetic renal injury.     

Human Polyomavirus Infection in Renal Allograft Recipients

Cytological and virological studies on 74 patients with functioning renal allografts were undertaken to detect polyomavirus infection of the renal tract. Ten patients (13·5%) were excreting polyomavirus. Virus particles were seen in the electron microscope in urine samples from eight patients. B.K. polyomavirus was isolated from four patients. Infection with a different polyomavirus was probable in one patient. Virus isolation was most readily achieved when large numbers of intact virus particles were seen in the urine. Patients who were excreting large amounts of polyomavirus shed numerous inclusion-bearing cells which could be detected by cytology. A serological study showed that the prevalence of B.K. antibody was similar to that found in the general population and 38% of this series of transplant patients had evidence of active infection with B.K. virus.     

Deaths from Occlusive Arterial Disease in Renal Allograft Recipients

In a series of 325 recipients of cadaveric renal transplants sudden occlusive arterial disease was found to be responsible for 12% of deaths. Acute myocardial infarction (9%) occurred 25 times more than expected in the normal population and cerebral thrombosis (3%) 300 times more. The greatest loss was in the initial three-month period after transplantation. Patients with renal failure due to essential hypertension were especially at risk, accounting for six of the 12 deaths.     

大鼠肾移植慢性排斥反应模型的建立

目的建立一种稳定的大鼠原位肾移植慢性排斥反应模型。方法供体为近交系F344大鼠,受体为Lewis大鼠,供肾采用左肾,在体修整,原位灌注。肾静脉用硬膜外导管做为临时内支架管端-端、六针法吻合,腹主动脉端-侧连续缝合,输尿管带膀胱瓣与膀胱吻合。受体术前3 d开始环孢素A灌胃至术后30 d（5 mg/kg·d）,以预防急性排斥反应。结果手术时间120～180 min;手术成功率90.9%（40P44）;受体均存活60 d。并发症有吻合口出血、静脉血栓形成、急性排斥反应等。结论供肾原位灌注,在体修整是简单可靠的方法。静脉內支架管端端吻合,腹主动脉端侧吻合能够达到稳定的成功率,值得推广。熟练的外科操作技能和血管吻合技术是手术成功的关键。     

Acute Kidney Injury Urinary Biomarker Time-Courses

Factors which modify the excretion profiles of acute kidney injury biomarkers are difficult to measure. To facilitate biomarker choice and interpretation we modelled key modifying factors: extent of hyperfiltration or reduced glomerular filtration rate, structural damage, and reduced nephron number. The time-courses of pre-formed, induced (upregulated), and filtered biomarker concentrations were modelled in single nephrons, then combined to construct three multiple-nephron models: a healthy kidney with normal nephron number, a non-diabetic hyperfiltering kidney with reduced nephron number but maintained total glomerular filtration rate, and a chronic kidney disease kidney with reduced nephron number and reduced glomerular filtration rate. Time-courses for each model were derived for acute kidney injury scenarios of structural damage and/or reduced nephron number. The model predicted that pre-formed biomarkers would respond quickest to injury with a brief period of elevation, which would be easily missed in clinical scenarios. Induced biomarker time-courses would be influenced by biomarker-specific physiology and the balance between insult severity (which increased single nephron excretion), the number of remaining nephrons (reduced total excretion), and the extent of glomerular filtration rate reduction (increased concentration). Filtered biomarkers have the longest time-course because plasma levels increased following glomerular filtration rate decrease. Peak concentration and profile depended on the extent of damage to the reabsorption mechanism and recovery rate. Rapid recovery may be detected through a rapid reduction in urinary concentration. For all biomarkers, impaired hyperfiltration substantially increased concentration, especially with chronic kidney disease. For clinical validation of these model-derived predictions the clinical biomarker of choice will depend on timing in relation to renal insult and interpretation will require the pre-insult nephron number (renal mass) and detection of hyperfiltration.     

The Renal Arterial Resistive Index and Stage of Chronic Kidney Disease in Patients with Renal Allograft

Objective

The study investigated the optimal threshold value of renal arterial resistive index as assessed by Doppler ultrasonography determining chronic kidney disease stage 4 or higher in patients with renal allograft.

Methods

In a cross-sectional study the renal arterial resistive index were obtained in interlobar arteries by Doppler ultrasonography in 78 patients with renal allograft. The stage of chronic kidney disease was determined by the estimated glomerular filtration rate equation.

Results

The median renal arterial resistive index was 0.61 (interquartile range, 0.56 to 0.66). We observed a significant association between renal arterial resistive index above the upper quartile and chronic kidney disease stage 4 or higher (relative risk, 4.64; 95% confidence interval, 1.71 to 12.55; p = 0.003 by Fisher’s exact test). Multivariate logistic regression analysis showed that renal arterial resistive indices (p = 0.02) and time since transplantation (p = 0.04), but not age, gender, or blood pressure were significantly associated with chronic kidney disease stage 4 or higher.

Conclusion

A renal arterial resistive index higher than 0.66 may determine the threshold value of chronic kidney disease stage 4 or higher in patients with renal allograft.     

Serum and Urinary Enzyme Activity After Renal Infarction

Recently it has been observed that the activity of certain enzymes in serum and urine may be increased after renal infarction. Although aortography or selective renal angiography should be the diagnostic corner-stone on which one would proceed to embolectomy, it is possible that enzyme assays may serve as laboratory aids to suggest or confirm the diagnosis. This paper reviews the few existing clinical and experimental studies and reports on two patients who had a total of three episodes of renal infarction. Serial determinations after one episode showed increased activity of serum oxaloacetic glutamic transaminase (SGOT) and of lactic acid dehydrogenase (LDH) and alkaline phosphatase in the serum and urine; some elevated serum LDH and SGOT values were recorded after the other two infarctions. The time of onset and duration of these increases are discussed, and the possible difficulty in differentiating renal from myocardial infarction is illustrated.     

Renal Ischaemia Reperfusion Injury: A Mouse Model of Injury and Regeneration

Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in patients and occlusion of renal blood flow is unavoidable during renal transplantation. Experimental models that accurately and reproducibly recapitulate renal IRI are crucial in dissecting the pathophysiology of AKI and the development of novel therapeutic agents. Presented here is a mouse model of renal IRI that results in reproducible AKI. This is achieved by a midline laparotomy approach for the surgery with one incision allowing both a right nephrectomy that provides control tissue and clamping of the left renal pedicle to induce ischaemia of the left kidney. By careful monitoring of the clamp position and body temperature during the period of ischaemia this model achieves reproducible functional and structural injury. Mice sacrificed 24 hr following surgery demonstrate loss of renal function with elevation of the serum or plasma creatinine level as well as structural kidney damage with acute tubular necrosis evident. Renal function improves and the acute tissue injury resolves during the course of 7 days following renal IRI such that this model may be used to study renal regeneration. This model of renal IRI has been utilized to study the molecular and cellular pathophysiology of AKI as well as analysis of the subsequent renal regeneration.     

Elevated Urine Heparanase Levels Are Associated with Proteinuria and Decreased Renal Allograft Function

Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains, leading to structural modifications that loosen the extracellular matrix barrier and associated with tumor metastasis, inflammation and angiogenesis. In addition, the highly sulfated heparan sulfate proteoglycans are important constituents of the glomerular basement membrane and its permselective properties. Recent studies suggest a role for heparanase in several experimental and human glomerular diseases associated with proteinuria such as diabetes, minimal change disease, and membranous nephropathy. Here, we quantified blood and urine heparanase levels in renal transplant recipients and patients with chronic kidney disease (CKD), and assessed whether alterations in heparanase levels correlate with proteinuria and renal function. We report that in transplanted patients, urinary heparanase was markedly elevated, inversely associated with estimated glomerular filtration rate (eGFR), suggesting a relationship between heparanase and graft function. In CKD patients, urinary heparanase was markedly elevated and associated with proteinuria, but not with eGFR. In addition, urinary heparanase correlated significantly with plasma heparanase in transplanted patients. Such a systemic spread of heparanase may lead to damage of cells and tissues alongside the kidney.The newly described association between heparanase, proteinuria and decreased renal function is expected to pave the way for new therapeutic options aimed at attenuating chronic renal allograft nephropathy, leading to improved graft survival and patient outcome.     

抗体介导的慢性排斥反应中内皮细胞基因的变化及分子机制

目前,抗体介导的慢性肾移植排斥反应难以预测,尚无有效的治疗方法。研究表明,通过对内皮细胞相关基因的分析,可以提高抗体介导的慢性肾移植排斥反应术前及术后的诊断特异性。该病的发病机制主要包括四个方面：（1）血小板在内皮细胞附近聚集凝固能力增强;（2）内皮细胞趋化炎性细胞作用增强;（3）干扰素-γ（IFN-γ）杀伤作用增强：（4）内皮修复再生能力降低。基因分析结合抗体分析有助于深化理解抗体介导的肾移植排斥反应的发病机理、提高诊疗效果、为新药开发提供新靶点,使肾移植成功率大幅提高成为可能。该篇综述将就上述内容作一介绍。     

运动性急性肾损伤与新型肾功能生物标志物

大强度运动中,非创伤性急性肾损伤（acute kindey injury, AKI）经常发生,表现为血尿、蛋白尿、血红蛋白尿等。一般认为,中低程度的运动性急性肾损伤是可逆的,可完全恢复。但动物实验与人类研究均发现,严重的运动性肾损伤会导致“功能性”急性肾损伤发展为“结构性”急性肾损伤,并增加慢性肾病的风险。运动性急性肾损伤对机体的潜在健康威胁已引起国内外相关领域学者的广泛关注。血清肌酐 (serum creatinine, Scr)和尿量作为肾功能的传统经典标志物,不能特异性反映早期肾损伤,而新型肾损伤标志物可进一步明确损伤的位置及严重程度。在运动领域,利用新型生物标志物进行无创性检查,识别早期运动性急性肾损伤非常必要。本文综述了反映肾小球或肾小管损伤、细胞周期停滞和肾损伤修复的新型生物标志物,着重论述了尿中性粒细胞明胶酶相关脂质运载蛋白（NGAL)和肾损伤分子-1（KIM-1)与肾功能的关系,以及长时间耐力运动、急性运动和高强度间歇阻力运动3种运动形式对肾功能的影响,旨在引起重视,精准识别风险,及时进行早干预。     

运动性急性肾损伤与新型肾功能生物标志物

大强度运动中,非创伤性急性肾损伤（acute kindey injury, AKI）经常发生,表现为血尿、蛋白尿、血红蛋白尿等。一般认为,中低程度的运动性急性肾损伤是可逆的,可完全恢复。但动物实验与人类研究均发现,严重的运动性肾损伤会导致“功能性”急性肾损伤发展为“结构性”急性肾损伤,并增加慢性肾病的风险。运动性急性肾损伤对机体的潜在健康威胁已引起国内外相关领域学者的广泛关注。血清肌酐 (serum creatinine, Scr)和尿量作为肾功能的传统经典标志物,不能特异性反映早期肾损伤,而新型肾损伤标志物可进一步明确损伤的位置及严重程度。在运动领域,利用新型生物标志物进行无创性检查,识别早期运动性急性肾损伤非常必要。本文综述了反映肾小球或肾小管损伤、细胞周期停滞和肾损伤修复的新型生物标志物,着重论述了尿中性粒细胞明胶酶相关脂质运载蛋白（NGAL)和肾损伤分子-1（KIM-1)与肾功能的关系,以及长时间耐力运动、急性运动和高强度间歇阻力运动3种运动形式对肾功能的影响,旨在引起重视,精准识别风险,及时进行早干预。