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Background: Severe acute respiratory syndrome Coronavirus 2 has rapidly spread worldwide, with acute kidney injury (AKI) as one of the manifestations with unknown causal mechanisms. We aimed to investigate tubular injury by assessing tubular markers and their association with the severity of Coronavirus disease 2019 (COVID-19). Methods: We examined the associations between laboratory markers and urinary levels of N-acetyl-β-d-glucosaminidase (uNAG), β2-microglobulin (u β2MG), α1-microglobulin (u α1MG), and liver-type fatty acid binding protein (L-FABP). We studied 18 COVID-19 patients without previous chronic kidney disease and analyzed the relationship between the urinary biomarkers and inflammatory markers in patients with severe (n = 7) or non-severe (n = 11) COVID-19, defined by requirements of supplemental oxygen. Results: Fourteen patients (78%) showed abnormal urinalysis findings and two (11%) developed AKI. Patients with severe COVID-19 had significantly higher levels of proteinuria, uNAG, uβ2MG, uα 1MG, and L-FABP than those with non-severe disease. Serum levels of interleukin-6 (IL-6) were significantly higher on admission in all severe COVID-19 cases and correlated with the levels of L-FABP, uβ2MG, uα1MG, uNAG, and proteinuria. Moreover, the changes in serum IL-6 (ΔIL-6) levels from baseline to 7 days after admission significantly correlated with ΔL-FABP and Δuβ2MG. Conclusions: Levels of tubular injury markers, especially L-FABP and uβ2MG, were significantly associated with IL-6 levels even in patients with no evident AKI. This suggests that L-FABP and uβ2MG could be useful as early detective biomarkers for COVID-19 associated renal injury. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the levels of selected markers in patients who underwent planned or emergency coronary angiography and to examine if they correlated with the occurrence of AKI. Methods: The study included 52 patients who underwent planned or emergency coronary angiography and received contrast agent. Serum levels of markers (NGAL, L-FABP, KIM-1, IL-18) were analyzed in all patients using ELISA tests, at baseline, after 24 and 72 h from angiography. Results: 9.62% of patients developed CI-AKI. No significant differences were observed between markers levels in patients who developed CI-AKI and those who did not. After 24 h, serum levels of IL-18 were higher in patients with CI-AKI, however, this difference was on the verge of significance. Increase in serum NGAL, KIM-1 and IL-18 was observed after 24 h. Serum levels of biomarkers were insignificantly higher in group with CI-AKI. Significant changes in levels in time (baseline vs. 24 h vs. 72 h) were observed only for NGAL [157.9 (92.4–221.0) vs. 201.8 (156.5–299.9) vs. 118.5 (73.4–198.7); p < 0.0001]. No significant correlations were observed between the decrease in eGFR or the increase in creatinine and biomarkers level. Conclusion: Obtained results do not allow for the indication of efficient AKI biomarkers. Their further validation in large studies of CI-AKI patients is required. [ABSTRACT FROM AUTHOR]

Background: Congenital obstructive uropathy (OU) is a leading cause of pediatric kidney failure, representing a unique mechanism of injury, in part from renal tubular stretch and ischemia. Tubular injury biomarkers have potential to improve OU-specific risk stratification. Methods: Patients with OU were identified in the Chronic Kidney Disease in Children (CKiD) study. "Cases" were defined as individuals receiving any kidney replacement therapy (KRT), while "controls" were age- and time-on-study matched and KRT free at last study visit. Urine and plasma neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), and liver-type fatty acid-binding protein (L-FABP) levels were measured at enrollment and annually and compared between cases and controls. Urine values were normalized to urine creatinine. Results: In total, 22 cases and 22 controls were identified, with median (interquartile range) ages of 10.5 (9.0–13.0) and 15.9 (13.9–16.9) years at baseline and outcome, respectively. At enrollment there were no differences noted between cases and controls for any urine (u) or plasma (p) biomarker measured. However, the mean pNGAL and uL-FABP/creatinine increased throughout the study period in cases (15.38 ng/ml per year and 0.20 ng/ml per mg/dl per year, respectively, p = 0.01 for both) but remained stable in controls. This remained constant after controlling for baseline glomerular filtration rate (GFR). Conclusions: In children with OU, pNGAL and uL-FABP levels increased over the 5 years preceding KRT; independent of baseline GFR. Future studies are necessary to identify optimal cutoff values and to determine if these markers outperform current clinical predictors. [ABSTRACT FROM AUTHOR]

Acute kidney injury (AKI) is a serious complication of pediatric cardiac surgery, with high morbidity and mortality. We aimed to evaluate the perioperative risk factors for AKI, and the validity of novel diagnostic urinary biomarkers after pediatric cardiac surgery. We analyzed 103 consecutive pediatric patients (≤ 18 years old), who underwent cardiac surgery. AKI was defined by ≥ 50% increase in serum creatinine levels from baseline. Urinary liver-type fatty acid binding protein (L-FABP) and neutrophil gelatinase-associated lipocalin (NGAL) were measured postoperatively at the intensive care unit (ICU) admission, subsequently at 4, 12, and 24 h. Areas under the receiver-operating characteristic curves (AUC) were calculated at each assessment time. AKI had developed in 47 patients (45.6%) by the second postoperative day. Univentricular status, aortic cross-clamping time, and intraoperative fluid balance were independently associated with AKI (p = 0.02, 0.01 and 0.01, respectively). Urinary L-FABP and NGAL were significantly higher in the AKI group at each point (p < 0.05). The predictive abilities of both biomarkers (AUC = 0.78–0.90) at ICU admission and 4 h after were especially high. The patients with L-FABP greater than the cutoff value at ICU admission and 4 h after ICU admission had significantly longer intubation and hospitalization periods (p < 0.05). Those with elevated NGAL levels at admission, and 4 h and 24 h after ICU admission, had significantly longer intubation, ICU stay, and hospitalization (p < 0.05). L-FABP and NGAL can be useful biomarkers for detecting early AKI after pediatric cardiac surgery and predicting adverse clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: Renal dysfunction is recognized with increasing frequency among the noninfectious comorbidities associated with human immunodeficiency virus (HIV) infection. Urinary liver-type fatty acid-binding protein (L-FABP) has been shown to be a new biomarker to screen for not only tubulointerstitial damage but also kidney dysfunction. Methods: We performed a cross-sectional study to determine the association between the urinary L-FABP and chronic kidney disease (CKD) among 77 HIV-infected Japanese patients by backward-stepwise multivariable logistic regression. Results: The prevalence of individuals in the low risk was 80 %. Urinary L-FABP level was not associated with antiretroviral therapy and tenofovir disoproxil fumarate. On the other hand, urinary L-FABP level was independently associated with the CKD classification. Conclusion: Urinary L-FABP may be used as an adjunct to diagnose the CKD stage. [ABSTRACT FROM AUTHOR]

Acute kidney injury (AKI) is a common complication after coronary angiography. Early biomarkers of this disease are needed since increase in serum creatinine levels is a late marker. To assess the usefulness of urinary kidney injury molecule-1 (uKIM-1), neutrophil gelatinase-associated lipocalin (uNGAL) and liver-type fatty acid-binding protein (uL-FABP) for early detection of AKI in these patients, comparing their performance with another group of cardiac surgery patients. Biomarkers were measured in 193 patients, 12 h after intervention. In the ROC analysis, AUC for KIM-1, NGAL and L-FABP was 0.713, 0.958 and 0.642, respectively, in the coronary angiography group, and 0.716, 0.916 and 0.743 in the cardiac surgery group. Urinary KIM-1 12 h after intervention is predictive of AKI in adult patients undergoing coronary angiography, but NGAL shows higher sensitivity and specificity. L-FABP provides inferior discrimination for AKI than KIM-1 or NGAL in contrast to its performance after cardiac surgery. This is the first study showing the predictive capacity of KIM-1 for AKI after coronary angiography. Further studies are still needed to answer relevant questions about the clinical utility of biomarkers for AKI in different clinical settings. [ABSTRACT FROM AUTHOR]

Background: Acute tubular necrosis (ATN) describes a form of intrinsic acute kidney injury (AKI) that results from persistent hypoperfusion and subsequent activation of the immune system. A glycosylated transmembrane protein, CD147/basigin, is involved in the pathogenesis of renal ischemia and fibrosis. The present study investigated whether CD147 can reflect pathological features and renal dysfunction in patients with AKI. Methods: Plasma and spot urine samples were collected from 24 patients (12 controls and 12 with ATN) who underwent renal biopsy between 2008 and 2012. In another study, patients undergoing open surgery to treat abdominal aortic aneurysms (AAAs) were enrolled in 2004. We collected urine and plasma samples from seven patients with AKI and 33 patients without AKI, respectively. In these experiments, plasma and urinary CD147, and urinary l-fatty acid-binding protein ( l-FABP) levels were measured, and the former expression in kidneys was examined by immunostaining. Results: In biopsy tissues of ATN with severe histological features, CD147 induction was strikingly present in inflammatory cells such as macrophages and lymphocytes in the injured interstitium, but not in damaged tubules representing atrophy. Both plasma and urinary CD147 levels were strikingly increased in ATN patients; both values showed greater correlations with renal dysfunction compared to urinary l-FABP. In patients who had undergone open AAA surgery, urinary and plasma CD147 values in AKI patients were significantly higher than in non-AKI patients at post-operative day 1, similar to the profile of urinary l-FABP. Conclusion: CD147 was prominent in its ability to detect AKI and may allow the start of preemptive medication. [ABSTRACT FROM AUTHOR]

Background: Acute kidney injury (AKI) is a common postoperative complication following cardiopulmonary bypass (CPB) surgery. New biomarkers to identify patients with early AKI (before increases in serum creatinine) are needed to facilitate appropriate treatment. This study aimed to test the role of urinary liver fatty-acid-binding protein (L-FABP) as an early biomarker for AKI in children undergoing CPB surgery. Methods: This is a case-control study of children undergoing CPB. AKI was defined as 50 % increase in serum creatinine at 48 h after surgery. For each patient, five serum and urine samples were obtained corresponding to time 0 h (presurgery) and 2, 6, 24, and 48 h after surgery. Results: Twenty-seven patients, median age 360 days, were enrolled. AKI developed in 11 patients (41 %); three needed renal replacement therapy (peritoneal dialysis); there were two deaths. There were significant differences between patients with and without AKI in L-FABP levels at 2, 6, and 48 h after surgery, length of hospital stay, and CPB time; there were no differences in gender, patient age, and body weight. L-FABP was normalized to urinary creatinine concentration at all time points, with area under the receiver operator curve (AUC ROC) 0.867 at 2 and 6 h postoperatively. Correlation coefficient between L-FABP and length of hospital stay after surgery was statistically significant ( r = 0.722, p value = 0.000). Conclusions: Our results suggest that urinary L-FABP can be used to diagnose AKI earlier than rise in serum creatinine in children undergoing CPB. [ABSTRACT FROM AUTHOR]

The prevalence of diabetic nephropathy has tremendously increased with the relentless rise in the incidence of diabetes over the last couple decades. Diabetic nephropathy is a leading cause of morbidity and mortality, and it invariably leads to an end-stage renal disease (ESRD). In an effort to delay the onset of ESRD systematic screening and appropriate management are needed to evaluate the progression of renal damage in diabetic nephropathy. The reliability of current tests in predicting the onset, progression and response to various regimens for diabetic nephropathy is still under debate; and it has engendered a search for more sensitive and specific urinary biomarkers, especially those reflective of tubular dysfunctions. It is well-known that there is a good correlation between the degree of damage to the tubulo-interstitial compartment and the deterioration of renal functions. In view of this, the utility of urinary biomarkers, reflective of tubular injury, reported in the literature is discussed in this brief review. [ABSTRACT FROM AUTHOR]

Liver fatty acid binding protein (L-FABP) is a member of intracellular lipid-binding proteins responsible for the transportation of fatty acids. The expression pattern of duck L-FABP mRNA was examined in this study by quantitative RT-PCR. The results showed that duck L-FABP gene was expressed in many tissues, including heart, lung, kidney, muscle, ovary, brain, intestine, stomach and adipocyte tissues, and highly expressed in liver. Several lipid metabolism-related genes were selected to detect the regulation of L-FABP in duck. The expression of L-FABP and lipoprotein lipase was promoted by oleic acid. The L-FABP knockdown decreased the expression levels of peroxisome proliferator-activated receptor α (PPARα), fatty acid synthase and lipoprotein lipase by 61.1, 42.3 and 53.7 %, respectively ( P < 0.05), but had no influences on the mRNA levels of PPARγ and leptin receptor. L-FABP might function through the PPARα to regulate the fat metabolism-related gene expression and play important roles in lipid metabolism in duck hepatocytes. [ABSTRACT FROM AUTHOR]

The small intestine contains three distinct proteins belonging to the intracellular lipid binding protein family: the liver-type fatty acid binding protein (L-FABP), the intestinal fatty acid binding protein (I-FABP) and the ileal lipid binding protein (ilbp). The function of these proteins in the small intestine has remained enigmatic. Targeted gene disruption studies may shed insights into the physiological importance of these proteins. In the case of I-FABP, this approach has demonstrated that the complete elimination of this protein in murine intestine does not compromise dietary fat absorption in vivo but is associated with the development of insulin resistance. [ABSTRACT FROM AUTHOR]

FABPs in the various tissues play an important role in the intracellular fatty acid transport and metabolism. Reye's syndrome (RS) and multisystemic lipid storage (MLS) are human disorders characterized by a disturbance of lipid metabolism of unknown etiology. We investigated for the first time L-FABP in these two conditions. Affinity purified antibodies against chicken L-FABP were raised in rabbits, and found to cross-react specifically with partially purified human L-FABP. L-FABP content in liver samples of two patients with RS and MLS was investigated by immuno-histochemistry, SDS-PAGE and ELISA. L-FABP immuno-histochemistry showed increased reactivity in the liver of RS patient and normal reactivity in MLS liver. L-FABP increase in RS liver was confirmed by densitometry of SDS-PAGE and ELISA method. By these two methods the increase amounted to 180% and 199% (p < 0.02), respectively, as compared to controls. A possible role of L-FABP in the pathogenesis of RS is discussed. [ABSTRACT FROM AUTHOR]

Background: This study's aim is to measure liver-type fatty acid-binding protein (L-FABP) levels in urine using a rapid semiquantitative assay kit in the emergency department and to investigate whether the onset of acute kidney injury (AKI) after hospitalization can be predicted. Methods: This was a prospective observation study. Patients transferred to the emergency and critical care center were divided into two groups: urinary L-FABP negative and positive groups. The status and severity of AKI were evaluated for the respective patients based on the Kidney Disease: Improving Global Outcome (KDIGO) classification. We compared the proportion of AKI patients in the two groups. Results: In the urine L-FABP-positive group, many patients had a significant onset of AKI (p < 0.001). After excluding patients who were diagnosed as AKI for creatinine level at admission, urinary L-FABP could predict the onset of AKI after admission (p < 0.001). Conclusion: By measuring urinary L-FABP concentration using a rapid semiquantitative assay kit, there is the possibility that the onset of AKI after admission can be predicted from immediately after a patient is transported by ambulance. [ABSTRACT FROM AUTHOR]