Increased Urinary Neutrophil Gelatinase Associated Lipocalin Levels in a Rat Model of Upper Urinary Tract Infection

Urinary Tract Infections Detection with Molecular Biomarkers

Urinary tract infection (UTI) is the most prevalent kind of pathogenic bacteria infection, and the midstream urine culture is regarded as the gold standard in UTI diagnosis. Recently, even with modern media and techniques such as polymerase chain reaction (PCR), urinary cultures still create a considerable workload for hospital laboratories. Other UTI-detecting methods, such as flow cytometry and lateral flow immunoassay, suffer from various drawbacks like long time consumption and low sensitivity. Therefore, looking for reliable biomarkers in UTI is urgently needed. In this review, the current definitions of UTI can be basically divided into two main categories: uncomplicated UTI and complicated UTI. In light of anatomical sites, it can be classified as either lower UTI or upper UTI. We take the classification of UTI as a clue and review the reported extensive literature to classify the existing studied markers into the following three categories: Biomarkers used clinically; Promising biomarkers; and Controversial biomarkers. Particularly, the nucleic acid-associated, metabolomic, and lipidomic biomarkers are highlighted. At the end, we discuss the challenges and prospects of biomarkers in UTI, hoping to further inspire the diagnosis of UTI.

Comprehensive insights into UTIs: from pathophysiology to precision diagnosis and management

Urinary tract infections (UTIs) are the second most common infectious disease, predominantly impacting women with 150 million individuals affected globally. It increases the socio-economic burden of society and is mainly caused by Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter spp., and Staphylococcus spp. The severity of the infection correlates with the host factors varying from acute to chronic infections. Even with a high incidence rate, the diagnosis is mainly based on the symptoms, dipstick analysis, and culture analysis, which are time-consuming, labour-intensive, and lacking sensitivity and specificity. During this period, medical professionals prescribe empirical antibiotics, which may increase the antimicrobial resistance rate. Timely and precise UTI diagnosis is essential for addressing antibiotic resistance and improving overall quality of life. In response to these challenges, new techniques are emerging. The review provides a comprehensive overview of the global burden of UTIs, associated risk factors, implicated organisms, traditional and innovative diagnostic methods, and approaches to UTI treatment and prevention.

Evaluation of diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin in patients with symptoms of urinary tract infections: a meta-analysis

Introduction

Early and accurate diagnosis of urinary tract infection (UTI) can prevent serious sequelae including chronic kidney disease. Multiple individual studies have identified urine neutrophil gelatinase-associated lipocalin (uNGAL) as a promising biomarker for early diagnosis of UTI. We sought to understand the distribution and diagnostic accuracy of uNGAL values in patients presenting with UTI symptoms.

Methods

Our systematic literature reviews in PubMed, Embase, and Cochrane Reviews up to March 2024, identified 25 studies reporting mean/median, standard deviation/quartiles, and detection limits of uNGAL in symptomatic patients with and without culture-confirmed UTI. Seventeen studies were in children. Meta-analyses were performed using the quantile estimation (QE) method estimating the distributions of uNGAL, which were then compared between the UTI and non-UTI groups for identifying the best cut-off points maximizing the Youden index. Sensitivity analyses were performed on all 25 studies including adult patients.

Results

We found that uNGAL levels were significantly higher in samples with confirmed UTI compared to those without. In pediatric studies, median and 95% confidence interval (CI) of uNGAL values were 22.41 (95% CI of 9.94, 50.54) ng/mL in non-UTI group vs. 118.85 (95% CI of 43.07, 327.97) ng/mL in UTI group. We estimated the cut-off point of 48.43 ng/mL with highest sensitivity (96%) and specificity (97%) in children. Sensitivity analysis including both pediatric and adult studies yielded similar results.

Discussion

The level of uNGAL in symptomatic patients with confirmed UTI is much higher than that reported in patients without UTI. It may be used as a diagnostic tool to identify UTI early among symptomatic patients. The range of uNGAL concentrations and cut-off points reported in subjects with UTI is much lower than that reported in patients with acute intrinsic kidney injury.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023370451).

The Utility of Noninvasive Urinary Biomarkers for the Evaluation of Vesicoureteral Reflux in Children

Vesicoureteral reflux (VUR) is one of the most important disorders encountered in pediatric nephrology due to its frequency and potential evolution to chronic kidney disease (CKD). The aim of our study was to identify noninvasive and easy-to-determine urinary markers to facilitate the diagnosis and staging of VUR. We performed a cross-section study including 39 patients with VUR followed over three years (August 2021-September 2023) and 39 children without urinary disorder (the control group). We measured the urinary concentration of interleukin-6 (IL-6), cathelicidin (LL-37), and neutrophil gelatinase-associated lipocalin (NGAL) in VUR and healthy controls. Moreover, we analyzed the correlation between these biomarkers and the presence of renal scars (RS), reflux nephropathy (RN), and CKD. The NGAL concentrations were significantly higher in patients with VUR than in the controls (p = 0.02). Regarding the severity of the reflux, NGAL/creatinine and LL-37/creatinine were positively correlated with severe reflux (p = 0.04, respectively, p = 0.02). In patients with VUR and RS, LL-37/creatinine was significantly lower (p = 0.01). LL-37/creatinine with an AUC of 0.71 and NGAL/creatinine with an AUC of 0.72 could be acceptable diagnostic tests for severe VUR. In conclusion, urinary IL-6, NGAL, and LL-37 could serve as valuable markers for diagnosing and predicting outcomes in patients with VUR and RN.

Febrile Urinary Tract Infections in Children: The Role of High Mobility Group Box-1

BACKGROUND

Differentiating between febrile lower urinary tract infection (LUTI) and acute pyelonephritis (APN) is crucial for prompt clinical management. We investigated whether the high mobility group box-1 (HMGB1) could be a useful biomarker in differentiating between LUTI or APN.

METHODS

We enrolled seventy-four pediatric patients with suspected LUTI/APN, according to the positive or negative renal scintigraphy (DMSA) scan. If the first DMSA findings were abnormal, a second DMSA was performed after six months. Voiding cystourethrography ruled out vesicoureteral reflux (VUR).

RESULTS

Higher serum (s) HMGB1 levels characterized the APN group when compared to LUTI patients (13.3 (11.8-14.3) versus 5.9 (5.2-6.8) ng/mL, p: 0.02), whereas there were no differences according to urine (u) HMGB1 values. sHMGB1 correlated with C-reactive protein (CRP) levels (β = 0.47; p: 0.02). Receiver operating characteristic curves identified the best diagnostic profile for detecting APN. sHMGB1 area under the curve was different from CRP (p: 0.01) and white blood cells (p: 0.003). After multivariate analyses, VUR (HR:4.81) and sHMGB1 (HR 1.16; p: 0.006) were independently associated with the risk of renal scarring development.

CONCLUSIONS

sHMGB1 could represent a marker to differentiate APN from LUTI. Measurement of sHMGB1 could select children for early intervention or long-term follow-up.

Assessment of early kidney injury caused by asymptomatic bacteriuria in children with type 1 diabetes

Introduction

Infection is one of the most frequent causes of morbidity and mortality in diabetic patients. Some microorganisms become more virulent in a high glucose concentration. Diabetics are more likely to have asymptomatic and symptomatic bacteriuria. NGAL is secreted in high concentrations into the blood and urine within two hours of AKI.

Objectives

The aim of the study is early detection of UTI in type1diabetic children through screening of their urine samples, and measurement of NGAL urinary levels in cases with asymptomatic bacteriuria for early detection of AKI to prevent serious complications.

Patients and methods

One thousand twenty-two known diabetic children on regular follow up in endocrine outpatient clinic at Minia Children University hospital were screened for UTI. From them only 52 diabetic children were diagnosed as asymptomatic bacteriuria (group I), 52 diabetic children with normal urine analysis (group II) and 52 apparently healthy children, age and sex matched, served as controls (group III). CBC, Renal function test, HbA1c, hs- CRP, Albumin/creatinine ratio, urine examination, urine culture, GFR and urinary NGAL were done to all children.

Results

Thirty-seven females (71.2%) had asymptomatic bacteriuria, Hs CRP and urinary NGAL were significantly higher, while GFR was significantly lower in diabetic children with bacteriuria than the other two groups. For diabetic children with bacteriuria, (AUC) for NGAL was 1 with optimal cutoff value of > 44.1 (Sensitivity 100% and Specificity 100%) while AUC for hsCRP was 0.887 with optimal cutoff value of > 1 (Sensitivity 82.69% and Specificity 90.38%).

Conclusion

Routine urine analysis should be done for all diabetic children even if they are asymptomatic. NGAL and hsCRP are non-invasive methods that could detect early renal injury in these patients thus, early, and proper management of UTI should be started to prevent renal injury.

Efficacy and safety of tailin formulation combined with continuous low-dose antibiotic therapy in patients with recurrent urinary tract infection: A multicenter, randomized, controlled clinical trial

Persistent inflammation associated with recurrent urinary tract infection (rUTI) is a crucial inducement of inflammation-driven renal fibrosis (IDRF). Although continuous low-dose antibiotic therapy (CLAT) is the common treatment for rUTI, its clinical efficacy remains unsatisfactory. Tailin formulation (TLF), a Chinese herbal formulation prescribed for treating rUTI, is effective in alleviating symptoms and reducing recurrence. This study was to evaluate the efficacy and safety of TLF combined with CLAT compared with CLAT used alone in patients with rUTI. In this multicenter, randomized, controlled clinical trial, patients were assigned (1:1) to receive either TLF + CLAT or CLAT for 12 weeks. The primary outcome was the effective rate at week 12 of the treatment. The secondary outcomes were the recurrent rate at week 4 and week 12 post treatment; the post-treatment changes in renal tubular injury markers (urinary N-acetyl-β-d-glucosaminidase (NAG) and β2-microglobulin (β2-MG)), profibrotic factors (urinary monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor beta1 (TGF-β1)), and traditional Chinese medicine (TCM) symptoms, and vital signs indicators and serious adverse events (SAEs) were also monitored throughout the trial. A total of 195 patients were included in the final analysis. The TLF + CLAT group had a higher effective rate and a lower recurrence rate than the CLAT group (p < 0.01). Significant decrease of urinary NAG and β2-MG was observed in the TLF + CLAT group vs. CLAT group (p < 0.01), and similar changes were observed in profibrotic factors (urinary MCP-1 and TGF-β1) (p < 0.05), which indicated that TLF might have potential renal tubular protection and anti-fibrosis effects. Additionally, a positive correlation within a certain range was shown in the correlation analysis of medical history (months) of rUTI patients with urinary MCP-1 (r = 0.50, p < 0.05) and TGF-β1 (r = 0.78, p < 0.01). A significant difference was also observed in TCM symptoms (p < 0.01). There were no obvious adverse reactions that occurred during this study. We conclude that TLF combined with CLAT was superior to CLAT used alone in reducing rUTI recurrence, alleviating the non-infection-related physical symptoms and protecting renal tubular and anti-fibrosis, which suggests this novel therapy might be an available treatment with great promise in treating rUTI.

A Systematic Review of the (Un)known Host Immune Response Biomarkers for Predicting Recurrence of Urinary Tract Infection

Recurrent urinary tract infections (rUTI) represent a major healthcare and economic burden along with a significant impact on patient’s morbidity and quality of life, even in the absence of well-known risk factors, such as vesicoureteral reflux. Despite numerous attempts to find a suitable therapeutic option, there is no clear benefit of any currently available intervention for prevention of UTI recurrence and its long-term consequences such as hypertension, renal scarring and/or insufficiency. The common treatment practice in many centers around the globe involves the use of continuous low-dose antibiotic prophylaxis, irrespective of various studies indicating increased microbial resistance against the prophylactic drug, leading to prolonged duration and escalating the cost of UTI treatment. Moreover, the rapid appearance of multi-drug resistant uropathogens is threatening to transform UTI to untreatable disease, while impaired host-microbiota homeostasis induced by a long-term use of antibiotics predisposes patients for various autoimmune and infectious diseases. New biomarkers of the increased risk of UTI recurrence could therefore assist in avoiding such outcomes by revealing more specific patient population which could benefit from additional interventions. In this light, the recent findings suggesting a crucial role of urothelial innate immunity mechanisms in protection of urinary tract from invading uropathogens might offer new diagnostic, prognostic and even therapeutic opportunities. Uroepithelial cells detect uropathogens via pattern recognition receptors, resulting in activation of intracellular signaling cascade and transcription factors, which ultimately leads to an increased production and secretion of chemokines, cytokines and antimicrobial peptides into the urinary stream. Emerging evidence suggest that the disturbance of a single component of the urinary tract innate immunity system might increase susceptibility for rUTI. The aim of the current review is to update clinicians and researchers on potential biomarkers of host immune response alterations predisposing for rUTI and propose those well worth exploring further. For this purpose, over a hundred original papers were identified through an extensive PubMed and Scopus databases search. This comprehensive review might enrich the current clinical practice and fill the unmet clinical needs, but also encourage the development of therapeutic agents that would facilitate urinary bacterial clearance by enhancing the host immune response.

Urinary tract infections in children: Testing a novel, noninvasive, point-of-care diagnostic marker

OBJECTIVES

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) appears highly accurate to identify urinary tract infections (UTIs) when obtained via catheterization. Our primary aim was to determine the agreement in uNGAL levels between paired catheter and bag urine specimens. Our secondary aim was to compare the diagnostic test characteristics of quantitative uNGAL, dipstick uNGAL (a potential point-of-care test), and urinalysis (UA).

METHODS

This was a prospective study of febrile children < 24 months evaluated for UTIs. We evaluated quantitative uNGAL at a previously identified threshold of 39.1 ng/mL, dipstick uNGAL at its built-in threshold of >50 ng/mL, and UA at standard thresholds for leukocyte esterase (LE). A positive urine culture was defined as >100,000 CFUs/mL of a pathogen.

RESULTS

A total of 211 patients were included (10% with positive urine cultures); 116 had paired catheterized and bagged samples. The agreement between catheterized and bagged samples at a quantitative uNGAL cutoff of ≥39.1 ng/mL was 0.76 (95% confidence interval [CI] = 0.67 to 0.83) and 0.77 (95% CI = 0.68 to 0.84) at a uNGAL dipstick threshold of >50 ng/mL. The area under the receiver operating characteristic curve for uNGAL from a catheterized sample was 0.96 (95% CI = 0.89 to 1.00) compared to 0.93 (95% CI = 0.87 to -0.99) from a bagged sample. The sensitivities of catheterized sample quantitative and dipstick uNGAL (90.5%) were higher than UA at a LE threshold of ≥1+ (57.1%). Bagged-sample uNGAL had lower quantitative and dipstick specificities (both 73.8%) than from catheterized samples (94.3% and 95.3% respectively), similar to UA.

CONCLUSIONS

uNGAL from bagged and catheterized samples showed insufficient agreement to be used interchangeably. The low specificity of uNGAL from bagged samples suggests that sampling technique affects uNGAL levels.

Urinary neutrophil gelatinase-associated lipocalin: a marker of urinary tract infection among febrile children

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a valuable biomarker of urinary tract infection (UTI) in children.

PURPOSE

This study aimed to compare the diagnostic accuracy of urinary NGAL (uNGAL) with those of serum C-reactive protein (CRP) and white blood cell (WBC) count for predicting UTI and acute pyelonephritis (APN) in febrile children.

METHODS

The medical charts of children undergoing uNGAL measurements between November 2017 and August 2019 were retrospectively reviewed. Patients with a suspected or diagnosed UTIs were included. The diagnostic accuracies of uNGAL, serum CRP, and WBC count for detecting UTI and APN were investigated. Independent predictors of UTI and APN were investigated using multivariable logistic regression analyses.

RESULTS

A total of 321 children were enrolled in this study. The uNGAL levels were higher in the UTI group (n=157) than in the non-UTI group (n=164) (P<0.05). Among children with a UTI, uNGAL levels were higher in the APN group (n=70) than, the non-APN group (n=87) (P<0.05). In the multivariate analysis, uNGAL was independently associated with UTI and APN (both P<0.05). Serum CRP and WBC count were not correlated with the presence of UTI and APN. Receiver operating curve analyses showed that the uNGAL level had the highest area under the curve (AUC) for predicting UTI and APN, respectively (AUC, uNGAL vs. CRP vs. WBC count, 0.860 vs. 0.608 vs. 0.669 for UTI; 0.780 vs. 0.680 vs. 0.639 for APN, all P<0.05, respectively). The predictive values and likelihood ratios of uNGAL were superior to those of serum CRP and WBC count for detecting UTI and APN at each cutoff level.

CONCLUSION

UNGAL may be more useful than serum CRP and WBC count for identifying and assessing UTI in febrile children.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

Diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin and urine kidney injury molecule-1 as predictors of acute pyelonephritis in young children with febrile urinary tract infection

Introduction

We assessed whether two urinary biomarkers of acute kidney injury, neutrophil gelatinase associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1), can be useful for predicting acute pyelonephritis (APN) in children aged 1-24 months with the first febrile urinary tract infection (UTI).

Material and methods

A prospective study included 54 children divided into two groups (24 with APN, 30 with lower UTI), according to the dimercaptosuccinic acid (DMSA) renal scintigraphy results. Laboratory tests: uNGAL, uKIM-1, procalcitonin (PCT), C-reactive protein (CRP), white blood count (WBC) were performed.

Results

We did not find significant differences in normalized and non-normalized values of uNGAL and uKIM-1 in children with APN and lower UTI. Positive correlations were determined between uNGAL and pyuria (r = 0.28, p < 0.05) and between uNGAL/uCr and uKIM-1/uCr (r = 0.53, p < 0.001) in the all UTI groups. Univariate logistic regression analysis demonstrated that only PCT (p < 0.0001) and CRP (p < 0.05) were important diagnostic factors of APN. Receiver operating curve (ROC) analysis showed good diagnostic profiles of PCT with the best cut-off value of 1.66 ng/ml and of CRP with the best cut-off value of 4.3 mg/dl for predicting APN (area under the curve [AUC]: 0.894 and 0.719, sensitivity: 75% and 96%, specificity: 93% and 43%, respectively).

Conclusions

uNGAL and uKIM-1 are not effective diagnostic markers for APN in young children with febrile UTI and cannot be used in clinical practice to differentiate APN from lower UTI.

Serum neutrophil gelatinase-associated lipocalin for predicting acute pyelonephritis in infants with urinary tract infection

Introduction

Fever and elevated inflammatory markers have been used for diagnosis of acute pyelonephritis (APN) in infants with urinary tract infection (UTI).

The aim of the study was to compare the usefulness of serum neutrophil gelatinase-associated lipocalin (sNGAL) with inflammatory markers for predicting APN in infants with UTI.

Material and methods

The prospective study included 46 infants with a first episode of UTI, divided into two groups (APN 23, lower UTI 23), according to the DMSA scan results. The following laboratory tests were performed: sNGAL, PCT, CRP, WBC, and ESR.

Results

Significantly elevated levels of sNGAL, PCT, CRP, and ESR were observed in infants with APN compared to those with lower UTI. Higher sNGAL, CRP, and ESR values, presence of fever, and longer duration of fever before antibiotic treatment were associated with APN [odds ratio (OR) 1.02, 1.27, 1.03, 13.46, 2.12, respectively]. Receiver operating characteristic (ROC) analysis showed better diagnostic profiles for sNGAL, PCT, and CRP than for ESR for predicting APN [area under the curve (AUC) 0.808, 0.819, 0.841, and 0.750, respectively]. The appropriate cut-off values of sNGAL, PCT and CRP were 100.8 ng/ml, 0.15 ng/ml, 5.3 mg/dl (all sensitivity and specificity 82.6%), and that of ESR was 40 mm/h (sensitivity 78.3%, specificity 60.9%).

Conclusions

sNGAL shows similar usefulness as PCT and CRP for predicting APN in infants with UTI, the diagnostic value of ESR is smaller, and WBC is not useful at all. The presence of fever and longer duration of fever are important predictors of APN in infants with UTI.

Urinary Neutrophil Gelatinase Associated Lipocalin - A Sensitive Marker for Urinary Tract Infection in Children

Early antibiotic treatment for urinary tract infection (UTI) in young children can prevent renal scarring. Sensitivity of pyuria and positive urine nitrite test as indicators of UTI are low, whereas results of urine culture, the gold standard for diagnosing UTI, may not be available for 48--72 h. Novel markers for rapid and accurate diagnosis of UTI would help in the early initiation of treatment in children with suspected UTI. We studied the utility of urinary neutrophil gelatinase-associated lipocalin (NGAL) as an early marker of UTI. This study included 100 children between 3 months and 5 years with suspected UTI. After parental consent, a midstream clean catch or suprapubic aspirate urine specimen was sent for culture and NGAL analysis. Sensitivity and specificity of urine NGAL as a marker of UTI were estimated. Of the 100 children evaluated, urine culture was positive in 34%. Median urine NGAL values were higher in culture-positive children than in culture-negative children (223.20 vs 13.65, P = 0.0001). Receiver operating curve analysis showed an optimal cutoff level of 27 ng/ml for urine NGAL (odds ratio, 8.2, 95% confidence interval, 3.1--22.1) correlating best with culture positivity. Sensitivity and specificity of urine NGAL estimation were significantly better (79.4% and 68.2%) when compared with urine white blood cell estimation (70.6% and 53%). Urine NGAL is a sensitive and specific marker to predict UTI in children with a cutoff level of 27 ng/ml. It may serve as a screening test for detecting simple, uncomplicated UTI in young children.

Urinary Neutrophil Gelatinase-Associated Lipocalin for the Diagnosis of Urinary Tract Infections

OBJECTIVES

To determine the accuracy of the novel biomarker urinary neutrophil gelatinase-associated lipocalin (uNGAL) to diagnose urinary tract infections (UTIs) in febrile infants and young children.

METHODS

Prospective cross-sectional study of febrile infants <3 months ( ≥ 38.0°C) and children 3 to 24 months (≥ 39.0°C) evaluated for UTIs. uNGAL levels, urinalysis, Gram-stain and culture were obtained. UTI was defined by colony counts.

RESULTS

Of 260 patients, 35 (13.5%) had UTIs. Median uNGAL levels were 215.1 ng/mL (interquartile range: 100.3-917.8) and 4.4 ng/mL (interquartile range: 1.6-11.8) in the groups diagnosed with and without UTIs, respectively. The area under the receiver-operating characteristic curve for uNGAL was 0.978 (95% confidence interval [CI]: 0.948-1.000). At a threshold uNGAL level of 39.1 ng/mL, sensitivity was 97.1% (95% CI: 83.4-99.9) and specificity was 95.6% (95% CI: 91.7-97.7). uNGAL had higher sensitivity than the combination of leukocyte esterase (in trace or greater amounts) or nitrite (+) (97.1%, 95% CI: 83.4-99.9 vs 74.3%, 95% CI: 56.4-86.9), with similar specificity (95.6%, 95% CI: 91.7-97.7 vs 97.3%, 95% CI: 94.0-98.9). uNGAL had higher sensitivity than Gram-stain (97.1%, 95% CI: 83.4-99.9 vs 74.3%, 95%: CI: 56.4-86.9), with similar specificity (95.6%, 95% CI: 91.7-97.7 vs 100.0%, 95% CI: 97.9-100.0).

CONCLUSIONS

uNGAL has substantial accuracy to identify those with and without UTIs in infants and young children. Further studies will need to confirm our findings and determine if uNGAL is a more cost-effective test than standard screening tests.

Metabolic phenotyping in the mouse model of urinary tract infection shows that 3-hydroxybutyrate in plasma is associated with infection

Urinary tract infection is one of the most common bacterial infections worldwide. Current diagnosis of urinary tract infection chiefly relies on its clinical presentation, urine dipstick tests and urine culture. Small molecules found in bio-fluids related with both infection and recovery would facilitate diagnosis and management of UTI. Mass spectrometry-based fingerprinting of plasma and urine at 3 time points, pre-infection (t = -24h), infection (t = 24h) and post 3-day treatment (t = 112h), were acquired in the following four groups: mice which were healthy, infected but not treated, infected and treated with ciprofloxacin, and infected and treated with Relinqing^® granules (n = 6 per group). A metabolomics workflow including multivariate analysis and ROC regression was employed to select metabolic features that correlated with UTI and its treatment. Circa 4,000 molecular features were acquired for each sample. The small acid 3-hydroxybutyrate in plasma was found to be differentiated for urinary tract infection, with an area under the curve = 0.97 (95% confidence interval: 0.93–1.00, accuracy = 0.91, sensitivity = 0.92 and specificity = 0.91). The level of 3-hydroxybutyrate in plasma was depleted after infection with a fold change of -22 (q < 0.0001). Correlation between plasma 3-hydroxybutyrate and urine bacterial number in all groups and time points was r = -0.753 (p < 0.0001). The findings show that 3-hydroxybutyrate is depleted in blood and strongly associated with UTI at both infection and post-treatment stage in a UTI mouse model. Further work is envisaged to assess the clinical potential of blood tests to assist with UTI management.

Plasma neutrophil gelatinase-associated lipocalin: a marker of acute pyelonephritis in children

OBJECTIVES

This study was designed to compare the diagnostic accuracy of plasma neutrophil gelatinase-associated lipocalin (NGAL) with procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBCs) for predicting acute pyelonephritis (APN) in children with febrile urinary tract infections (UTIs).

MATERIALS AND METHODS

In total, 138 children with febrile UTIs (APN 59, lower UTI 79) were reviewed retrospectively. Levels of NGAL, PCT, CRP, and WBCs in blood were measured on admission. The diagnostic accuracy of the biomarkers was investigated. Independent predictors of APN were identified by multivariate logistic regression analysis.

RESULTS

Receiver operating curve (ROC) analyses showed good diagnostic profiles of NGAL, PCT, CRP, and WBCs for identifying APN [area under the curve (AUC) 0.893, 0.855, 0.879, and 0.654, respectively]. However, multivariate analysis revealed only plasma NGAL level was an independent predictor of APN (P = 0.006). At the best cutoff values of all examined biomarkers for identifying APN, sensitivity (86 %), specificity (85 %), positive predictive value (81 %), and negative predictive value (89 %) of plasma NGAL levels were the highest. The optimal NGAL cutoff value was 117 ng/ml. The positive likelihood ratio [odds ratio (OR) 5.69, 95 % confidence interval (CI) 3.56-8.78], and negative likelihood ratio (OR 0.16, 95 % CI 0.08-0.29) of plasma NGAL for APN diagnosis also showed it seemed to be more accurate than serum PCT, CRP, and WBCs.

CONCLUSION

Plasma NGAL can be more useful than serum PCT, CRP, and WBC levels for identifying APN in children with febrile UTIs.

Neutrophil gelatinase-associated lipocalin: utility in urologic conditions

Neutrophil gelatinase-associated lipocalin (NGAL) is best known as a non-invasive early marker of acute kidney injury (AKI). However, recent published reports have described additional utility of both plasma NGAL (pNGAL) and urine NGAL (uNGAL) in various pathologic conditions within the pediatric urinary tract, including urinary tract infection, vesicoureteral reflux (VUR), renal scarring, and obstructive uropathy. These two forms of NGAL have different applications related to their mechanisms of upregulation: pNGAL can serve as a marker of systemic inflammatory conditions, whereas uNGAL is specific for insults to the renal epithelium. Therefore, pNGAL has good predictive accuracy in systemic inflammation associated with pyelonephritis and renal damage, while uNGAL is an effective marker for identifying infection within the genitourinary environment as well as subclinical renal damage as a result of scarring or obstruction. Continued work should focus on the effect of trending NGAL values in patients with pyelonephritis, VUR, and hydronephrosis, to determine if longitudinal NGAL patterns have value in predicting adverse outcomes.

Neutrophil Gelatinase-Associated Lipocalin: A Biomarker for Early Diagnosis of Urinary Tract Infections in Infants

Early diagnosis of urinary tract infection (UTI) is challenging in infants due to unspecific symptoms, difficulty in urine collection and possible contamination. The aim of this study was to assesses the usefulness of serum and urine neutrophil gelatinase-associated lipocalin (sNGAL and uNGAL, respectively) in the diagnosis of febrile and non-febrile UTI in infants. This prospective observational study enrolled 66 infants with the first episode of UTI and 18 healthy controls. At the time of enrollment, sNGAL, uNGAL, urinalysis, urine culture, white blood cell count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), and serum creatinine (sCr) were assessed. We found that, on average, both sNGAL and uNGAL levels were significantly higher in febrile UTI, compared to non-febrile UTI and controls. In turn, the mean sNGAL level, but not uNGAL, was significantly higher in the non-febrile UTI group compared to controls. sNGAL positively correlated with WBC, CRP, ESR and PCT, and uNGAL with CRP and leukocyturia. The receiver operating curves (ROC) demonstrate that the optimum cut-off of 76.2 ng/ml for sNGAL (sensitivity 92.9%, specificity 94.4%, and the area under the curve (AUC) of 0.98) and of 42.2 ng/ml for uNGAL (sensitivity 73.8%, specificity 72.2%, and AUC of 0.76) for diagnosing febrile UTI and 39.0 ng/ml for sNGAL (sensitivity 83.3%, specificity 55.6%, and AUC of 0.70) for diagnosing non-febrile UTI. In conclusion, serum NGAL is an excellent marker for the early diagnosis of febrile UTI, with sensitivity and specificity higher than those of urine NGAL. Diagnostic sensitivity of serum NGAL is smaller in non-febrile infants suffering from UTI, and urine NGAL is not useful for this purpose at all.

Role of new biomarkers for predicting renal scarring in vesicoureteral reflux: NGAL, KIM-1, and L-FABP

BACKGROUND

Reflux nephropathy is the most serious complication of vesicoureteral reflux (VUR). The aim of this study was to assess the role of urinary levels of neutrophil-gelatinase-associated lipocalin (NGAL),kidney injury molecule-1 (KIM-1), and liver-type fatty-acid-binding protein (L-FABP) in the early diagnosis of reflux nephropathy in patients with VUR.

METHODS

This study assessed 123 patients with primary VUR and 30 healthy children as a control group. The children were divided into five groups: Group A, patients with VUR and renal parenchymal scarring (RPS); Group B, patients with VUR and without RPS; Group C, patients with RPS and resolved VUR; Group D, patients with resolved VUR and without RPS; Group E, healthy reference group.

RESULTS

Median urinary NGAL (uNGAL)/Creatinine (Cr) was significantly higher in patients with than those without RPS and the control group (p = 0.0001). Median uKIM-1/Cr was similar in all groups (p = 0.417). Median uL-FABP/Cr was significantly higher in patients with RPS than in the reference group (p < 0.05).

CONCLUSIONS

Urinary NGAL levels may be used as a noninvasive diagnostic marker for predicting renal scarring in reflux nephropathy.

Plasma neutrophil gelatinase-associated lipocalin predicts acute pyelonephritis in children with urinary tract infections

BACKGROUND

The identification of acute pyelonephritis (APN) is still a challenge.

METHODS

Patients admitted for their first urinary tract infection (UTI) were enrolled. Plasma neutrophil gelatinase-associated lipocalin (NGAL) levels were measured at admittance and after treatment. Laboratory, clinical, and imaging results were compared between children with and without APN.

RESULTS

A total of 123 patients were enrolled (53 APN and 70 lower UTI). After adjusting for age and gender, plasma NGAL levels were higher in the APN group than in the lower UTI group (233 (129-496) ng/ml vs. 71 (50.8-110) ng/ml, P < 0.001). NGAL levels were correlated with the serum levels of leukocytes, C-reactive protein, and creatinine, as well as fever duration (P < 0.05). Multivariable analysis revealed that log-transformed plasma NGAL was an independent predictor of APN (P < 0.05). Receiver operating curve analysis showed a good diagnostic profile of NGAL for identifying APN (area under the curve 0.864) with a best cut-off value of 102.5 ng/ml. The NGAL levels in both two groups decreased after treatment compared to levels before treatment (P < 0.001).

CONCLUSION

Plasma NGAL can be a sensitive predictor for identifying APN and monitoring the treatment response of pediatric UTI.

Urinary neutrophil gelatinase-associated lipocalin (NGAL) might be an independent marker for anticipating scar formation in children with acute pyelonephritis

INTRODUCTION

Urinary tract infections (UTIs) are the most serious common bacterial infections among young children. It may affect kidneys that classified as acute pyelonephritis (APN) and may lead to renal parenchymal involvement and scarring with high prevalence rate (15%-60%) among children. This study aimed to assess the urinary concentration of neutrophil gelatinase-associated lipocalin (NGAL) in patients with APN to diagnose those with potency to scar formation.

PATIENTS AND METHODS

Children who were admitted with a diagnosis of APN were enrolled and divided into two groups; APN with scar and APN without scar. Urinary levels of NGAL and its ratio to creatinine (Cr) levels were measured in the acute phase of infection. A receiver operating characteristic (ROC) curve was generated to allow calculation of cut-off values.

RESULTS

Fifty-four children were enrolled across the 2 groups: group 1 consisted of 16 patients (all female); group 2 consisted of 38 children (36 female and 2 male). Urinary levels of NGAL were significantly higher in APN with scar than in APN without scar (P = 0.037). For comparison of groups 1 and 2, the cut-off values were measured as 7.32 ng/ml, sensitivity; 81.3% and specificity; 66%.

CONCLUSION

Evaluation of urinary NGAL levels may help us to identify children with APN who are at risk of developing renal scarring.

Short communication: Relationship between urinary neutrophil gelatinase-associated lipocalin and noninfectious pyuria in dogs

Neutrophil gelatinase-associated lipocalin (NGAL) is a neutrophil-derived protein whose concentration increases in plasma and urine with ongoing renal damage. Urinary leucocytes can be a potential source of urinary NGAL. The aim of this study is to investigate the effects of urinary neutrophil count and other urinary parameters on urinary NGAL values in urine with negative culture. Urinalysis, urine culture, and determination of urinary NGAL were performed on 33 clinically healthy nonproteinuric dogs with negative urinoculture. The median uNGAL concentration in dogs in this study population was 9.74 ng/mL (IQR 1.93–25.43 ng/mL). In samples with WBCs > 5 hpf (mean 15.9, 6–50 leucocytes/hpf), median uNGAL value was significantly higher than that in samples with WBCs < 5 hpf (mean 0.9, 0–3 leucocytes/hpf), (4.96 pg/mL (0.29–11.34) and 23.65 pg/mL (20.04–29.80), resp.; P = 0.0053). The severity of urinary pyuria and the UPC value were correlated with uNGAL concentration. The results of our study show that urinary NGAL concentration is correlated with WBCs number in urinary sediment of dogs with negative urinoculture. The present study suggests that noninfectious pyuria is significantly correlated with urinary NGAL values and might influence uNGAL values.

Neutrophil gelatinase-associated lipocalin and innate immune responses to bacterial infections

Neutrophil gelatinase-associated lipocalin (NGAL), an essential component of the antimicrobial innate immune system, is present in neutrophils and multiple other tissues. It prevents iron acquisition by microorganisms by sequestering iron-loaded bacterial siderophores. NGAL also modulates neutrophil functions. Its production is inducible following Toll-like receptor 4 activation and release of pro-inflammatory cytokines. NGAL is employed clinically in the diagnosis of acute kidney injury and may be useful in general in the differential diagnosis of a bacterial-mediated infectious process. Elevated levels of NGAL have been detected in the blood of patients with bacterial urinary tract infection, community-acquired pneumonia, sepsis, as well as in the cerebrospinal fluid and peritoneal fluid of patients with bacterial meningitis and peritonitis. Some bacteria have developed resistance to NGAL-mediated iron sequestration by production of modified siderophores that are not recognized by NGAL.

The diagnosis of febrile urinary tract infection in children may be facilitated by urinary biomarkers

BACKGROUND

We prospectively assessed the feasibility of two urinary markers of renal injury as potential diagnostic tests for acute febrile urinary tract infection (UTI) and subsequent renal scarring.

METHODS

The patient cohort comprised children aged 0 to 4 years who visited the emergency room. The children were divided into three groups, namely, a febrile UTI (fUTI), febrile control (FC) and a non-febrile control (NFC) group, respectively, which were matched for sex and age. An enzyme-linked immunosorbent assay for neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) was performed on urine collected from each child. The urine levels of both markers were compared between the three groups, and the diagnostic accuracy was determined based on the area under the receiver-operator characteristic curve (AUC). In the fUTI group, the predictability of subsequent renal scarring was assessed by associating urinary levels with dimercaptosuccinic acid findings 6 months after an UTI episode.

RESULTS

Significantly elevated levels of urinary NGAL and KIM-1 were observed in the fUTI group, as well as with increased urine esterase, serum C-reactive protein, and pyuria. The AUC was 72 % for KIM-1 and 96 % for NGAL. The AUC of KIM-1 for the prediction of scarring was 71 % (p < 0.05).

CONCLUSIONS

The diagnosis of febrile UTI and the prediction of subsequent scarring may be facilitated by assaying urine biomarkers with acceptable accuracy.

Predictive value of urinary and serum biomarkers in young children with febrile urinary tract infections

BACKGROUND

Early predictive biomarkers for the diagnosis and management of febrile urinary tract infections (UTIs) can be valuable diagnostic tools in children.

METHODS

The study cohort comprised 73 pediatric patients with febrile UTIs [46 with acute pyelonephritis (APN) and 27 with lower UTIs] and 56 healthy children. Urine neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1) levels and serum cystatin C (sCysC) levels were measured.

RESULTS

The uNGAL/creatinine (Cr) and uKIM-1/Cr levels were higher in the UTI group than in the controls (P < 0.05). uNGAL/Cr and sCysC levels were higher in patients with APN than in those with lower UTIs (P < 0.05). uNGAL/Cr levels in both the APN and UTI groups decreased following the administration of antibiotics compared to those before treatment (P < 0.05). The uNGAL/Cr level was correlated with serum levels of white blood cells, C-reactive protein, CysC and with uKIM-1/Cr (P < 0.05). uKIM-1/Cr was also correlated with sCysC (P < 0.05). Receiver operating curve analyses showed good diagnostic profiles of uNGAL/Cr and uKIM-1/Cr for identifying UTIs [area under the curve (AUC) 0.9 and 0.66, respectively) and of uNGAL/Cr and sCysC for predicting APN (AUC 0.78 and 0.72, respectively).

CONCLUSIONS

Our results suggest that uNGAL, uKIM-1 and sCysC levels may be useful for predicting and managing febrile UTIs in children.

Evaluation of the optimal neutrophil gelatinase-associated lipocalin value as a screening biomarker for urinary tract infections in children

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker in the detection of kidney injury. Early diagnosis of urinary tract infection (UTI), one of the most common infections in children, is important in order to avert long-term consequences. We assessed whether serum NGAL (sNGAL) or urine NGAL (uNGAL) would be reliable markers of UTI and evaluated the appropriate diagnostic cutoff value for the screening of UTI in children.

Methods

A total of 812 urine specimens and 323 serum samples, collected from pediatric patients, were analyzed. UTI was diagnosed on the basis of culture results and symptoms reported by the patients. NGAL values were measured by using ELISA.

Results

NGAL values were more elevated in the UTI cases than in the non-UTI cases, but the difference between the values were not statistically significant (P=0.190 for sNGAL and P=0.064 for uNGAL). The optimal diagnostic cutoff values of sNGAL and uNGAL for UTI screening were 65.25 ng/mL and 5.75 ng/mL, respectively.

Conclusions

We suggest that it is not appropriate to use NGAL as a marker for early diagnosis of UTI in children.

Urinary Measurement of Neutrophil Gelatinase Associated Lipocalin and Kidney Injury Molecule-1 Helps Diagnose Acute Pyelonephritis in a Preclinical Model

Background. The study assessed whether measurement of urinary biomarkers of acute kidney injury could be helpful in diagnosing acute pyelonephritis and subsequent scarring. Method. Escherichia coli J96 (0.3 mL inoculum containing 1 × 10⁹/mL) was directly injected into the renal cortex of 3-week-old female Sprague Dawley rats (n = 20), with saline substituted in a control group (n = 10). Following the injection, urine was collected 2, 7, 14, 28, and 42 days after injection. Urinary neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (Kim-1), and interleukin-18 were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). The levels of the biomarkers were adjusted for creatinine. Time course changes within a group or between the groups were compared. Correlation analysis was performed to understand the relationship between urinary levels and histological scarring. Results. Significantly elevated urinary NGAL was evident at two and seven days after injection, and Kim-1 was elevated at two days after injection. Receiver operating characteristic analyses confirmed the sensitivity of these markers at these times. No urinary marker at acute stage of APN was correlated with the amount of future scarring, negating their predictive value. Conclusion. Urinary NGAL and Kim-1 could be helpful in diagnosing febrile urinary tract infection in children.

Elevation of neutrophil gelatinase-associated lipocalin (NGAL) in non-azotemic dogs with urinary tract infection

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker in humans and dogs with kidney disease. This protein is expressed by many cells including renal tubular cells and neutrophils. The aim of this study was to evaluate the effect of urinary tract infection (UTI) on urinary NGAL (uNGAL) concentration in dogs. Urine culture and measurement of uNGAL level were performed in 80 non-azotemic dogs suspected of UTI and 19 healthy dogs. Dogs were divided in three groups: 19 healthy dogs, 25 dogs with positive culture and 55 dogs suspected of UTI but with negative culture. uNGAL and uNGAL/Creatinine was significantly higher (P < 0.0001) in dogs with UTI (14.22 ng/mL;19.74 μg/g) compared to Healthy (0.24 ng/mL;0.11 μg/g) and Negative (1.13 ng/mL;1.28 μg/g) dogs. A uNGAL value <3.38 ng/mL had a negative predictive value for UTI of 87%. Presence of UTI has to be considered when uNGAL is used to detect kidney disease.

Clinical application neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 as indicators of inflammation persistence and acute kidney injury in children with urinary tract infection

Background. The aim of this study was to examine the novel renal biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) to assist pediatricians in the assessment of longer duration of inflammation and acute kidney injury (AKI) development during urinary tract infection (UTI). Methods. The patients enrolled in the study comprised 50 children (mean age was 6 months) with UTI. NGAL in serum and urine (sNGAL and uNGAL, resp.) and KIM-1 in urine were measured by enzyme-linked immunosorbent assays. Results. uNGAL levels in subjects with longer duration of inflammation were higher (115.37 ng/mL) than uNGAL levels in subjects with shorter duration of inflammation (67.87 ng/mL, P = 0.022). Difference in sNGAL and KIM-1 levels was not significant (P = 0.155 and P = 0.198, resp.). Significant difference was seen in KIM-1 excretion among groups with and without AKI (P = 0.038). KIM-1 was not able to discriminate between subjects with and without AKI (area under the curves (AUC) = 0.620, P = 0.175). Conclusions. uNGAL cannot be used for screening of the duration of inflammation during UTI. Accuracy of KIM-1 in screening of AKI development in children with UTI is low. We suggest larger studies to check the negative predictive value of KIM-1 for the development of AKI.

Kidney safety during surgical pneumoperitoneum: an experimental study in rats

BACKGROUND

Elevations of intraabdominal pressure during laparoscopic procedures may lead to oliguria or anuria in mammals. Despite this, previous research has not been able to confirm an associated kidney injury. This study aimed to investigate the occurrence of an early kidney lesion secondary to surgical pneumoperitoneum in a rat model using the expression of neutrophil gelatinase-associated lipocalin (N-GAL) as a biomarker for early kidney injury.

METHODS

In this study, 20 male Sprague-Dawley rats under general anesthesia and mechanically ventilated were allocated to one of five experimental time-dependent groups: group 1 (1-h control), group 2 (1-h pneumoperitoneum), group 3 (2-h control), group 4 (2-h pneumoperitoneum), and group 5 (positive kidney injury group induced by intravenous administration of cisplatin 7.5 mg/kg). To evaluate the renal expression of N-GAL 24 h after the procedure, all the rats underwent a 2-h urine output evaluation as well as laparotomy and bilateral nephrectomy performed sequentially to investigate the presence of renal injury using immunofluorescence qualification and western blotting.

RESULTS

Urine output was reduced and N-GAL expression was increased in the animals from the cisplatin group. The animals undergoing 1- or 2-h pneumoperitoneum displayed urine output and N-GAL expression similar to that of the animals from the matching control groups.

CONCLUSIONS

Under the experimental conditions of this study, the animals with normal preoperative renal function did not show any type of acute kidney injury associated with the presence of a stabilized surgical pneumoperitoneum.

Evaluation of the ARCHITECT urine NGAL assay: assay performance, specimen handling requirements and biological variability

OBJECTIVES

NGAL (Neutrophil Gelatinase-Associated Lipocalin) has emerged as a new biomarker for the identification of acute kidney injury. Reliable clinical evaluations require a simple, robust test method for NGAL, and knowledge of specimen handling and specimen stability characteristics. We evaluated the performance of a new urine NGAL assay on the ARCHITECT analyzer.

METHODS

Assay performance characteristics were evaluated using standard protocols. Urine specimen storage requirements were determined and biological variability was assessed in a self-declared apparently healthy population.

RESULTS

Assay performance data showed good precision, sensitivity and lot-to-lot reproducibility. There was good short term 2-8 degrees C sample stability, however, long term storage samples must be kept at -70 degrees C or colder. The largest variance component in a biological variance study was within-day.

CONCLUSIONS

The ARCHITECT NGAL assay proved to be a precise and reproducible assay for the determination of urine NGAL.

Early prediction of urinary tract infection with urinary neutrophil gelatinase associated lipocalin

Neutrophil gelatinase associated lipocalin (NGAL) is a protein identified in human neutrophil granules. The aim of the study was to assess whether urine level of NGAL (uNGAL) could represent a novel, reliable marker of urinary tract infection (UTI) and to determine the optimal cutoff level for uNGAL to predict UTI in children. Sixty patients with symptomatic UTI and 29 healthy controls were enrolled the study. Urine NGAL was measured by enzyme-linked immunosorbent assay. A dimercaptosuccinic acid (DMSA) radionuclide scan was performed within 7 days in the patients with UTI in an attempt to distinguish pyelonephritis from cystitis. Mean uNGAL level was significantly higher in the UTI group than in the controls (91.02 ng/ml vs 14.29 ng/ml, p = 0.0001) and using a cutoff 20 ng/ml for uNGAL for diagnosis of UTI, sensitivity, and specificity were 97% and 76%, respectively [area under the curve (AUC): 0.979]. Mean uNGAL/creatinine ratio (uNGAL/Cr) was also significantly higher in the UTI group [201.81 ng/mg creatinine (Cr) vs 18.08 ng/mg Cr; p = 0.0001], and using a cutoff 30 ng/mg Cr for uNGAL/Cr for diagnosis of UTI, sensitivity and specificity were 98% and 76%, respectively (AUC: 0.992). In conclusion, both uNGAL and uNGAL/Cr can be used as a novel, sensitive marker for early prediction of UTI in the absence of acute kidney injury and chronic kidney disease, and the optimal cutoff value for prediction of UTI is lower than the values determined for acute kidney injury. Further investigations with larger patient groups are required to confirm our results.