Urinary Retinol-binding Protein Research Articles

Combined biomarkers evaluation for diagnosing kidney injury in preeclampsia

Objective: To identify novel potential biomarkers and evaluate combined biomarkers for diagnosing kidney injury with considerable accuracy in preeclampsia. Methods: The level of serum and urine neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), retinol-binding protein (RBP) and interleukin-18 (IL-18) were measured by enzyme-linked immunosorbent assay. Results: The level of serum cystatin C, urine RBP, urine NGAL and urine KIM-1 in preeclampsia group were higher than that in the normal pregnancy group. When four biomarkers are combined, the sensitivity and specificity are 100%/98.20%. Conclusion: Urine KIM-1 is the most potential biomarker for renal injury in preeclampsia. The more biomarkers combined, the more sensitivity and specificity were increased.

Evaluation of snake envenomation-induced renal dysfunction in dogs using early urinary biomarkers of nephrotoxicity

Renal dysfunction in dogs envenomed by poisonous snakes is currently detected using traditional serum and urinary biomarkers such as creatinine and proteinuria. However, these markers lack sensitivity at the early stages of renal dysfunction and their diagnostic accuracy is affected by pre-analytical factors commonly occurring in these dogs, such as haemolysis and haemoglobinuria. Early detection of renal dysfunction would allow for the identification of dogs requiring intensive treatment and monitoring and may help inform prognosis. The aim of this study was to evaluate the performance of several novel urinary biomarkers of glomerular dysfunction, namely, urinary albumin (uAlb), immunoglobulin G (uIgG) and C-reactive protein (uCRP) and of proximal tubular dysfunction (urinary retinol binding protein (uRBP)) compared to traditional end points in dogs with renal damage caused by snake envenomation. Biomarker results were compared between 19 dogs bitten by snakes producing either neurotoxins or cytotoxins and 10 clinically healthy controls.uAlb, uIgG, and uRBP were significantly increased in snake-envenomed dogs at presentation compared to controls, whereas only uIgG and uCRP were significantly elevated 24h post-envenomation. The urinary protein:creatinine ratio was also increased in envenomed dogs compared to controls, but because of the presence of haematuria and haemoglobinuria, differentiation between pre-renal and renal proteinuria was not possible. The results showed that these novel urinary biomarkers may assist in better detecting renal dysfunction in dogs envenomed by poisonous snakes at the acute disease stage compared to traditional laboratory endpoints.

Associations of Urinary Cadmium with Age and Urinary Proteins: Further Evidence of Physiological Variations Unrelated to Metal Accumulation and Toxicity

Background: The current risk assessment for environmental cadmium (Cd) largely relies on the assumption that urinary Cd (U-Cd) is a reliable biomarker of the Cd body burden. Recent studies have questioned the validity of this assumption.Objectives: We studied the lifetime trend of U-Cd as a function of diuresis, gender, smoking status, and protein tubular reabsorption. We also analyzed the associations between U-Cd and urinary proteins.Methods: Cd, retinol-binding protein, and albumin were measured in the urine of six cohorts of the general population of Belgium, with a mean age ranging from 5.7 to 88.1 years (n = 1,567). Variations of U-Cd with age were modeled using natural cubic splines.Results: In both genders, U-Cd decreased to a minimum (~ 0.20 μg/L) at the end of adolescence, then increased until 60–70 years of age (~ 0.60 μg/L in never-smokers) before leveling off or decreasing. When U-Cd was expressed in micrograms per gram of creatinine, these variations were amplified (minimum, 0.15 µg/g creatinine; maximum, 0.70 µg/g creatinine) and much higher U-Cd values were observed in women. We observed no difference in U-Cd levels between never-smokers and former smokers, and the difference with current smokers did not increase over time. Lifetime curves of U-Cd were higher with increasing urinary retinol-binding protein or albumin, a consequence of the coexcretion of Cd with proteins.Conclusions: At low Cd exposure levels, U-Cd and age are associated through nonlinear and nonmonotonic relationships that appear to be driven mainly by recent Cd intake and physiological variations in the excretion of creatinine and proteins.Citation: Chaumont A, Voisin C, Deumer G, Haufroid V, Annesi-Maesano I, Roels H, Thijs L, Staessen J, Bernard A. 2013. Associations of urinary cadmium with age and urinary proteins: further evidence of physiological variations unrelated to metal accumulation and toxicity. Environ Health Perspect 121:1047–1053; http://dx.doi.org/10.1289/ehp.1306607

Significance of low molecular weight urinary protein for assessment of early renal damage in patients with multiple myeloma

This study was purposed to evaluate the clinical significance of low molecular weight urinary proteins for diagnosis of early renal damage in patients with multiple myeloma (MM). Medical records of 278 patients with MM in Nanjing School of Clinical Medicine from January 2004 to May 2012 were analyzed retrospectively. These patients were divided into 3 groups: glomerular damage group (n = 143), tubular damage group (n = 114) and normal group (n = 21). The clinical and laboratorial data were compared among them. The correlations of urinary retinol-binding protein (RBP) or urinary N-acetyl-β-D-amino-glucosaminidase (NAG) with blood urea nitrogen (BUN), Scr, blood cystatin-C (Cys-C), clearance of creatinine (Ccr), 24 h protein uria and 24 h urine light chains were further analyzed, and the correlation of renal tubulointerstitial lesion scores with low molecular weight urinary proteins in 61 patients were also analyzed. The area under curve (ROC curve) was used to evaluate and compare the discrimination of urinary RBP and urinary NAG. The results showed that glomerular damage group had higher urinary RBP than tubular damage group. However, glomerular damage group had lower urinary NAG than tubular damage group. The two groups had higher urinary RBP and urinary NAG than that in normal group. Urinary RBP related positively to the level of Scr, BUN, Cys-C, 24 h proteinurias and related negatively to the level of Ccr. Urinary NAG related positively to the level of 24 h proteinurias, Ccr and related negatively to the level of Cys-C. Renal tubulointerstitial lesions were significantly correlated with urinary RBP, but weakly correlated with urinary NAG. It is concluded that urinary RBP significantly correlates with renal tubular damage. Compared with urinary NAG, urinary RBP can better assess the extent of renal damage, and has higher specificity.

Renal tubular dysfunction in children with sickle cell haemoglobinopathy

Children with sickle cell disease (SCD) are remarkably more prone than others to renal dysfunction. The kidneys, as one of the systemic long-term hazards in SCD, may be affected by both the haemodynamic changes of chronic anaemia as well as by the consequences of vaso-occlusion. The aim of this study was to evaluate the proximal tubular function in a group of Saudi children with established SCD. This study was conducted in Al-Khafji Joint Operations (KJO) Hospital, in Saudi Arabia during the period from June 2011 to August 2012. Thirty-four children: Group I (18 males and 16 females) with SCD (HBSS) and 27 children: Group II (17 males and 10 females) with sickle cell trait (HBAS) were evaluated for urinary excretion of retinol binding protein (RBP) and - Beta 2 microglobulin (β2 MG). Group I patients showed a significantly impaired urinary concentrating ability compared to that of Group II (417 ± 94 mOsm/kg vs 581 ± 165 mOsm/kg). The urinary excretions of RBP and β2-microglobulin were significantly higher in Group I than in Group II. The values were 762.01 ± 124.20 μg/L and 841.84 ± 389.02 μg/L versus 198.12 ± 42.24 μg/L and 298.3 ± 38.11 μg/L, respectively. Significant proximal tubular dysfunction was a feature in the SCD group, indicated by high urinary RBP and β2-microglobulin excretion. Assessing the urinary excretion of these low molecular weight proteins in children with sickle cell disease at different points of diagnosis may add key clinical information to the follow up of renal tubular function in patients with SCD.

Effect of remote ischaemic preconditioning on renal protection in patients undergoing laparoscopic partial nephrectomy: a ‘blinded’ randomised controlled trial

To evaluate whether remote ischaemic preconditioning (RIPC) reduces renal injury in patients undergoing laparoscopic partial nephrectomy (LPN). In all, 82 patients undergoing LPN were randomly assigned to either the RIPC or control group, with 40 and 38 patients, respectively completing 6-months follow-up. RIPC was conducted after induction of anaesthesia, which consisted of three 5-min cycles of right lower limb ischaemia and 5 min of reperfusion during each cycle. The primary outcome was the absolute change in glomerular filtration rate (GFR) of the affected kidney by renal scintigraphy from baseline to 6 months. The secondary outcomes included urinary retinol-binding protein (RBP) levels measured at 24 and 48 h, serum creatinine, and estimated GFR (eGFR) at 1 and 6 months, and changes in GFR by renal scintigraphy. There were no differences in the change of GFR of the affected kidney at 6 months, while it was significantly decreased by 15.0% in the control group vs 8.8% in the RIPC group at 1 month (P = 0.034). The urinary RBP levels increased 8.4-fold at 24 h in the control group compared with a lower increase of 3.9-fold in the RIPC group (P < 0.001). There were no differences in the serum creatinine level or eGFR at 1 and 6 months between the two groups. In patients undergoing LPN, RIPC using transient lower limb ischaemia may reduce renal impairment in the short term, but failed in the longer term despite a non-significant trend in favour of RIPC. These novel data support the need for a larger study of RIPC during LPN surgery.

Urine High and Low Molecular Weight Proteins One-Year Post-Kidney Transplant: Relationship to Histology and Graft Survival

Increased urinary protein excretion is common after renal transplantation and portends worse outcome. In this study we assessed the prognostic contribution of several urinary proteins. Urinary total protein, albumin, retinol binding protein (RBP), α-1-microglobulin, IgG and IgM were measured in banked urine samples from 221 individuals 1 year after renal transplantation (age 52 ± 13 years, 55% male, 93% Caucasian and 82% living donor). Levels of all proteins measured were higher than in normal nontransplant populations. Patients with glomerular lesions had higher urinary albumin than those with normal histology, while those with interstitial fibrosis and tubular atrophy plus inflammation (ci>0, cg = 0, i>0) had higher levels of IgG, IgM, α-1-microglobulin and RBP. Concomitant normal levels of urinary albumin, IgM and RBP identified normal histology (specificity 91%, sensitivity 15%,). Urinary levels of the specific proteins were highly correlated, could not differentiate among the histologic groups, and appeared to result from tubulointerstitial damage. Increased urinary excretion of the low molecular weight protein RBP was a sensitive marker of allografts at risk, predicting long-term graft loss independent of histology and urinary albumin. This study highlights the prognostic importance of tubulointerstitial disease for long-term graft loss.

Ag@BSA Core/Shell Microspheres As an Electrochemical Interface for Sensitive Detection of Urinary Retinal-Binding Protein

The level of urinary retinol-binding protein (RBP) can be estimated as a significant index of renal tubular injury. In this work, we used Ag@BSA microspheres as a sensing interface to cross-link RBP monoclonal antibody (RBP mAb) via glutaraldehyde for sensitive detection of RBP. The Ag@BSA microspheres covered on a Au electrode could provide a larger surface area and multifunctional substrate for the effective immobilization of RBP mAb, and the outside BSA layer acted as a biocompatible support to maintain the bioactivity and stability of immobilized immunogen. Electrochemical measurements containing electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were employed to evaluate the analytical performance of the fabricated immunosensor and a higher detection sensitivity was obtained by DPV attributed to the excellent electrical conductivity of Ag@BSA which could enhance the peak current response. This immunosensor had a best detection limit (DL) of 18 ng mL(-1) and a linear response range between 50 and 4500 ng mL(-1). The proposed approach showed high specificity for RBP detection, acceptable reproducibility with an RSD of 5.6%, and good precision with the RSD of 4.5% and 6.3% at the RBP concentrations of 500 and 1500 ng mL(-1). Compared with the ELISA method by analyzing real urine samples from a patient, this immunosensor revealed acceptable accuracy with a relative deviation lower than 6.5%, indicating a potential alternative method for RBP detection in clinical diagnosis.

Assessment of renal dysfunction using urinary markers in canine babesiosis caused by Babesia rossi

Renal damage is deemed a common, yet poorly documented, complication in canine babesiosis. Serum urea and creatinine are insensitive and non-specific markers of early renal dysfunction and their measurements are influenced by hemolysis caused by babesiosis. Therefore, the aim of this study was to use urinary markers to assess the localization and degree of renal dysfunction in dogs with Babesia rossi infection. Urinary immunoglobulin G (uIgG) and urinary C-reactive protein (uCRP) were measured as markers for glomerular dysfunction, while urinary retinol-binding protein (uRBP) was used as a marker for tubular dysfunction. Eighteen dogs presenting with uncomplicated babesiosis were included and compared with eight clinically healthy dogs. Previously validated commercial ELISA kits were used for the measurement of uIgG, uCRP, and uRBP. Results were related to urinary creatinine concentrations (c). Dogs with babesiosis had significantly higher concentrations of all three measured urinary markers compared to healthy dogs. Except for urinary protein/c ratio (UPC), routine urinary and serum markers for renal function (urine specific gravity (USG), serum urea and creatinine (sCr)) were not significantly different between dogs with babesiosis and healthy dogs. All three urinary markers were positively correlated with each other and with UPC. The data supports the presence of both glomerular and tubular dysfunction in dogs suffering from uncomplicated B. rossi infection. Urinary markers were superior to USG, serum urea and creatinine concentrations for the early detection of renal dysfunction in dogs with babesiosis.

Clinical and pathological spectrums of aristolochic acid nephropathy

To study the clinical and pathological characteristics of aristolochic acid nephropathy (AAN). 86 patients with AAN during 2001 and 2009 in our department were recruited in this retrospective study. The clinical and pathological features were analyzed. There were 47 males and 39 females, aging from 12 to 69 years old. Abnormal urine analysis and gastro-intestinal diseases were two main underlying causes for patients taking aristolochic acid (AA) containing drugs. All patients suffered from renal function impairment. 19 patients (22.0%) presented with acute kidney injury (AKI), while 67 patients (78%) presented as chronic cases. Among them, 31 patients (36.0%) lacked symptoms, 30 patients (34.8%) were accompanied with hypertension, and 26 patients (30.2%) presented with gastrointestinal symptoms. Laboratory examination revealed elevated urine retinol-binding protein (RBP) (90.7%) and urine N-acetyl-β-glucosaminidase (NAG) (80.2%). Anemia and glucosuria accounted for 64.0% and 58.1%, respectively. Renal biopsy showed prominent tubular brush border ablation (84.2%) in acute cases, while obvious tubular basement membrane (TBM) thickening (81.4%) and interstitial fibrosis were present in chronic cases. During the follow- up, 11 (57.9%) acute cases gained renal function recovery. They had lower urine RBP level and lower incidence of hypokalemia than the non-recovery acute cases. In the chronic group, 27 patients (40.2%) progressed to endstage renal disease (ESRD), with 11 dialysis and 5 renal transplantation cases. AAN patients usually suffered from renal impairment with an associated history of taking AA containing drugs. Proximal renal tubular dysfunction and structure destroying would be the main positive findings in laboratory tests and renal biopsy. Urine RBP and hypokalemia might determine the outcome of acute AAN patients.

Renal Evaluation in Women with Preeclampsia

Background/Aims: Preeclampsia (PE) is a cause of glomerulopathy worldwide. Urinary retinol-binding protein (RBP) is a marker of proximal tubular dysfunction, albuminuria is an endothelial injury marker, urine protein:creatinine ratio (PCR) may have a predictive value for renal disease later in life, and, recently, podocyturia has been proposed as a sensitive tool in pregnancy, but it needs to be tested. The aim of this study was to evaluate renal involvement in PE and healthy pregnancy. Methods: Case-control study with 39 pregnant women assessed after 20 weeks of gestation (25 in the control group, CG, and 14 in the PE group) by performing urinary tests. Results: Mean (±SD) age and gestational age of the CG were 26.9 ± 6.4 years and 37.1 ± 5.0 weeks, and of the PE group 26.4 ± 6.9 years and 30.6 ± 5.6 weeks, respectively (p = 0.001). Mean (±SD) urinary RBP (p = 0.017), albuminuria (p = 0.002), and urinary albumin concentration (UAC) ratio (p = 0.006) of the CG were 0.4 ± 0.7 mg/l, 7.3 ± 6.9 mg/l, and 8.2 ± 6.7 mg/g and of the PE group 2.0 ± 4.4 mg/l, 2,267.4 ± 2,130.8 mg/l (p = 0.002), and 3,778.9 ± 4,296.6 mg/g (p = 0.006), respectively. Mean (±SD) urine PCR in the PE group was 6.7 ± 6.1 g/g (p < 0.001). No statistical differences were found between podocyturia in the CG and PE group (p = 0.258). Conclusions: Urinary RBP, PCR, albuminuria, and UAC ratio were elevated in the PE group in comparison to the CG. Podocyturia did not predict PE.

The Reference Dose for Subchronic Exposure of Pigs to Cadmium Leading to Early Renal Damage by Benchmark Dose Method

Pigs were exposed to cadmium (Cd) (in the form of CdCl(2)) concentrations ranging from 0 to 32mg Cd/kg feed for 100 days. Urinary cadmium (U-Cd) and blood cadmium (B-Cd) levels were determined as indicators of Cd exposure. Urinary levels of β(2)-microglobulin (β(2)-MG), α(1)-microglobulin (α(1)-MG), N-acetyl-β-D-glucosaminidase (NAG), cadmium-metallothionein (Cd-MT), and retinol binding protein (RBP) were determined as biomarkers of tubular dysfunction. U-Cd concentrations were increased linearly with time and dose, whereas B-Cd reached two peaks at 40 days and 100 days in the group exposed to 32mg Cd/kg. Hyper-metallothionein-urinary (HyperMTuria) and hyper-N-acetyl-β-D-glucosaminidase-urinary (hyperNAGuria) emerged from 80 days onwards in the group exposed to 32mg Cd/kg feed, followed by hyper-β2-microglobulin-urinary (hyperβ2-MGuria) and hyper-retinol-binding-protein-urinary (hyperRBPuria) from 100 days onwards. The relationships between the Cd exposure dose and biomarkers of exposure (as well as the biomarkers of effect) were examined, and significant correlations were found between them (except for α(1)-MG). Dose-response relationships between Cd exposure dose and biomarkers of tubular dysfunction were studied. The critical concentration of Cd exposure dose was calculated by the benchmark dose (BMD) method. The BMD(10)/BMDL(10) was estimated to be 1.34/0.67, 1.21/0.88, 2.75/1.00, and 3.73/3.08mg Cd/kg feed based on urinary RBP, NAG, Cd-MT, and β(2)-MG, respectively. The calculated tolerable weekly intake of Cd for humans was 1.4 μg/kg body weight based on a safety factor of 100. This value is lower than the currently available values set by several different countries. This indicates a need for further studies on the effects of Cd and a re-evaluation of the human health risk assessment for the metal.

Hypertensive nephropathy in children – do we diagnose early enough?

Background/Aims. The aim was to evaluate the level of neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18) and retinol binding protein (RBP) in children with primary hypertension and no features of hypertensive nephropathy. Methods. The study group consisted of 19 children (15 males) aged 14.8 ± 2.18 years with primary hypertension. Estimated glomerular filtration rate (eGFR) and albumin/creatinine ratio (ACR) were within the normal range. Mean blood pressure (BP) was 141/79 mmHg (mean systolic BP percentile was 98, mean diastolic BP percentile was 80). Ambulatory BP measurement (ABPM), blood and urine biochemical measurements and features of end organ damage were assessed. The control group consisted of 20 healthy children. Results. Hypertensive children showed significantly increased serum and urine NGAL concentration vs controls. Urine RBP was significantly higher in the study group vs controls. A positive correlation was found between urine NGAL and the index of mean systolic BP measured in ABPM, between urine IL-18 and the index of office diastolic BP, between serum NGAL and ACR, and between urine NGAL concentration and serum HDL. Conclusion. In children with primary hypertension, increased serum and urine NGAL may reflect kidney injury earlier than typical markers of hypertensive nephropathy.

Comparative study on external use of mercury-containing preparation Badu Shengji San in sensitive monitoring indicators of induced early renal injury

To compare the sensitivity of early renal injury induced by mercury-containing medicine in rats, including urinary N-acetyl-beta-D-glucosdminidase (NAG), beta2-microglobulin (beta2-MG), retinol binding protein (RBP) and clusterin (CLU). Badu Shengji San(BDSJS), a mercury-containing preparation of traditional Chinese medicine, was adopted as the mercury contact drug. The lowest effective toxic dose was used to observe its effect on serum creatinine (SCr), blood urea nitrogen (BUN), and such early renal injury indicators as NAG, RBP, beta2-MG and CLU and compare the sensitivity of tested indicators. Compared to the broken skin group, groups with administration of 60 and 120 mg x kg(-1) doses of BDSJS showed no obvious difference in SCr and BUN when kidney indicators is remarkably increased and obvious pathological changes were found in kidney tubules but with significant increase in the urinary level of CLU and the levels of NAG and RBP. H&E staining of renal tubule showed that exposure of 30 mg x kg(-1) BDSJS had no significant morphological changes, but at the same concentrations, the level of RBP was markedly increased. Urinary beta2-MG levels were markedly decreased in BDSJS 30, 60 mg x kg(-1) group rats, whereas 120 mg x kg(-1) dose group showed no obvious change in urinary beta2-MG levels. Urinary RBP, NAG and CLU were more sensitive than SCr and BUN as indicators for early renal injury in the order of RBP > NAG > CLU, and urinary RBP, NAG would increase earlier than beta2-MG.

Comparison of effects of Badu Shengji San on rats with different injured skins

To compare the effects of Badu Shengji San (BDSJS) on rats with different injured skins. The injured and ulcerous skin rat model was established to observe the renal injury induced by BDSJS, a mercury-containing external preparation of Chinese medicine, with urinary N-acetyl-beta-D-glucosaminidase (NAG) and retinol binding protein (RBP) as indicators of renal toxicity. Compared to injured skin rats with the same dose, both of high and low-dose ulcerous skin groups showed obvious increase in urinary RBP and kidney coefficients, significant pathomorphological changes in renal tubules and notable epithelial cytopathic effects. In terms of NAG, the high-dose ulcerous skin group saw no significant increase, but the low-dose group recorded sharp rise. The renal toxicity induced by BDSJS in ulcerous skin rats was more toxic than that in injured skin ones.

Vitamin A deficiency associated with urinary retinol binding protein wasting in Dent’s disease

Three patients with Dent's disease presented with complaints of impaired night vision or xerophthalmia and were found to have severely decreased serum retinol concentrations. Retinol, bound to its carrier retinol-binding protein (RBP), is filtered at the glomerulus and reabsorbed at the proximal tubule. We hypothesized that urinary loss of retinol-RBP complex is responsible for decreased serum retinol. The study aim was to investigate vitamin A status and RBP in serum and urine of patients with genetically confirmed Dent's disease. Eight patients were studied, three boys had clinical vitamin A deficiency, three had asymptomatic deficiency, and two young men with Dent's disease and impaired renal function had normal retinol values. Serum RBP concentrations were low in patients with vitamin A deficiency and were correlated with vitamin A levels. Urinary RBP concentrations were increased in all patients (2,000-fold), regardless of vitamin A status. This was in contrast to patients with glomerular proteinuria who had only mildly increased urinary RBP with normal serum RBP and vitamin A, and patients with cystinosis with impaired renal function who had massive urinary RBP losses but without a decrease in serum RBP or vitamin A levels. Treatment with vitamin A supplements in patients with retinol deficiency resulted in rapid resolution of ocular symptoms and an increase in serum retinol concentrations. Vitamin A deficiency is common in patients with Dent's disease and preserved renal function. We therefore recommend screening these patients for retinol deficiency and treating them before visual symptoms develop.

Delayed Renal Function Recovery From Drug-Induced Acute Interstitial Nephritis

IntroductionAcute interstitial nephritis, considered one of the major causes of reversible acute kidney injury, was frequently encountered as drug-treatment complication in the early stage of infection control. In some cases, drug-induced acute interstitial nephritis (DIAIN) resulted in delayed function recovery or chronic kidney disease. To study the underlying mechanism, the authors investigated the clinical and pathological features of DIAIN patients with delayed renal function recovery. The delayed recovery group consisted of patients with reduced renal function for more than 3months after diagnosis. MethodsIn this retrospective study, 18 patients with DIAIN from January 2003 to December 2009 were identified as the delayed recovery group, whereas 54 patients with DIAIN who recovered completely within 3months were treated as the control group. Clinical and pathological features were compared between the 2 groups. ResultsIn the delayed recovery group, the average age at onset was 48.8years, antibiotics and herbs were the 2 main causative drugs and the dominant extra-renal manifestation was gastrointestinal symptomatology. In comparison with patients in the control group, patients in the delayed recovery group had longer interval time from disease onset to hospitalization, and they presented with less oliguria. Moreover, these patients had higher levels of urine retinol binding protein, and more renal interstitial inflammatory cell infiltrations were observed in their renal histology. ConclusionAging, long interval time from disease onset to hospitalization and renal interstitial inflammatory cell infiltration may predict delayed renal function recovery.

Analysis of molecular forms of urine Retinol-Binding Protein in Fanconi Syndrome and design of an accurate immunoassay

Background Retinol-Binding Protein in urine (uRBP), a biomarker for the proximal renal tubular disease of congenital and acquired Fanconi Syndrome (FS) occurs in multiple forms. However these have not had quantitative mass spectrometric (MS) analysis, nor is there a validated assay for defined molecular species of uRBP with linearity on sample dilution. Methods A ‘Top-down’ MS approach identified distinct forms of uRBP differing by only one amino acid. Based on this, we designed a dual-monoclonal antibody-based fluorescence immunoassay calibrated with intact plasma RBP4. Results LC–MS showed that uRBP in FS (one Dent disease urine) comprised intact plasma RBP4 and C-terminal-truncated RBP4, desL-RBP4 and desLL-RBP4 in molar ratio 2:2:1. DELFIA® assay calibrated with plasma RBP4, formulated with two monoclonal antibodies (HyTest, Finland), mAb48 for capture and biotinylated-mAb42 for detection, provided good sensitivity (1 μg/L), working range > 500 μg/L and good linearity on sample dilution. The three predominant forms of uRBP were equipotent over the assay working range. uRBP reference range was < 3 μg/mmol creatinine and FS patients had concentrations of 1000–5000 μg/mmol creatinine. Conclusions Using ‘Top-down’ MS analysis of uRBP we devised an accurate, linear, fluorescence immunoassay with defined RBP molecular targets optimal for uRBP measurement. Discrimination of elevated uRBP from the upper limit of normal was some 10-fold greater than previous assays.

Quantitative and Qualitative Urine Protein Excretion in Dogs with Severe Inflammatory Response Syndrome

Proteinuria is an established characteristic of renal disease in dogs, providing diagnostic and prognostic information. Little is known about the occurrence and severity of proteinuria in dogs with severe inflammatory response syndrome (SIRS). The quantitative and qualitative urinary protein (UP) excretion is altered in dogs with SIRS. Thirty-nine dogs with SIRS and 15 healthy control dogs at admission. A case control study was performed. Diagnosis of SIRS was based on clinical and clinicopathological findings. Urinary protein (UP) was measured by a colorimetric assay. Urinary albumin (UAlb) and urinary retinol-binding protein (URBP) were measured by ELISA and quantified in relation to urinary creatinine (UC). Sodium dodecyl sulfate polyacrylamid-gel electrophoresis was conducted to identify the qualitative pattern of proteinuria. Mann-Whitney U-test was used to assess differences in UP/UC, UAlb/UC and URBP/UC between the groups. P-values < .05 were considered significant. Dogs with SIRS had higher ratios of UP/UC, UAlb/UC and URBP/UC (all P < .001) in comparison to healthy control dogs. Dogs with SIRS had a total of 11 protein bands compared to 3 bands in healthy controls. In dogs with SIRS, 58% of the total counted bands were in the low molecular weight range (<60 kDa) whereas 42% were in the middle (60-80 kDa)/high molecular weight range (>80 kDa). SIRS alters UP excretion in dogs. Further studies should evaluate whether or not the magnitude of proteinuria is predictive of the severity and outcome of dogs with SIRS.

Primary focal segmental glomerulosclerosis in nephrotic patients: common complications and risk factors

Focal segmental glomerulosclerosis (FSGS) presents a range of potentially serious complications, including acute kidney injury (AKI), infection and thromboembolism. This study aimed to find out the incidence rates and risk factors for these complications in FSGS patients. Patients with biopsy-proven primary FSGS and nephrotic-range proteinuria were included in this study. A short-term (16-week) follow-up was performed to observe the aforementioned complications. Clinical characteristics of patients were recorded upon enrollment. AKI was diagnosed as an absolute increase in serum creatinine of ≥0.3 mg/dL or a percentage increase of ≥50% within 48 hours; infection, by a combination of clinical manifestations, laboratory tests and imaging examinations; and thromboembolism, by imaging methods. Risk factors for complications were evaluated by logistic regression model. The study population included 90 FSGS patients (63 males, mean age 28.9 ± 12.9 years). The incidences of AKI, infection and thromboembolism were 44.4%, 25.6% and 12.2%, respectively. Patients with AKI were more likely to be male, with lower serum albumin, greater proteinuria and more severe acute tubulointerstitial damage. Patients with infection had higher proteinuria and lower serum albumin, globulin and IgG. Circulating endothelial cells (CECs) and von Willebrand factor were higher in patients with thromboembolism. Logistic regression showed that increased urine retinol-binding protein, decreased serum albumin and IgG, and increased CECs and hemoglobin were independent risk factors for AKI, infection and thromboembolism, respectively. AKI, infection and thromboembolism are common among FSGS patients. Awareness of risk factors and prevention of these complications are important for the prognosis of these patients.