Urinary N-acetyl-β-D-glucosaminidase Research Articles

Urinary N-acetyl-β-D glucosaminidase as a surrogate marker for renal function in autosomal dominant polycystic kidney disease: 1 year prospective cohort study

BackgroundRenal failure is one of the most serious complications associated with autosomal dominant polycystic kidney disease (ADPKD). To date, early markers have failed to predict renal function deterioration at the early stages. This 1-year prospective study evaluated N-acetyl-β-D-glucosaminidase (NAG) as a new surrogate marker for renal function in ADPKD.MethodsA total of 270 patients were enrolled in the study, and we measured urinary NAG, β2-microglobulin, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) prospectively for 1 year to compare their predictive values for renal function.ResultsBaseline urinary NAG/Cr was negatively correlated with estimated glomerular filtration rate (GFR) (r2 = 0.153, P < 0.001) and positively correlated with total kidney volume (TKV) (r2 = 0.113, P < 0.001). Among other biomarkers, urinary NAG/Cr better discriminated patients with decreased renal function from those with conserved renal function, showing the largest area under the curve (AUC 0.794). Immunohistochemical study revealed strong staining along the cyst-lining epithelial cells as well as the nearby compressed tubular epithelial cells. However, both single and repeated measurements of urinary NAG/Cr failed to predict renal function decline in 1 year.ConclusionsUrinary NAG/Cr may be a useful surrogate marker for renal function in ADPKD patients.

Potential Role of Poly(ADP-Ribose) Polymerase (PARP) Activation in Methotrexate-Induced Nephrotoxicity and Tubular Apoptosis

Nephrotoxicity is one of the serious dose-limiting complications of methotrexate (MTX) when used in the treatment of various malignancies and nononcological diseases. The aim of this study was to investigate the role of poly(adenosine diphosphate ribose) polymerase (PARP) activity in MTX-induced nephrotoxicity. Rats were divided into 4 groups as control, MTX treated (MTX, 7 mg/kg per d, intraperitoneally [ip], once daily for 3 consecutive days), MTX plus 1,5-isoquinelinediol (ISO, a PARP inhibitor, 3 mg/kg per d, i.p.) treated, or ISO treated. Histopathology of kidneys was evaluated by light microscopy. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay was used to analyze apoptosis in kidney sections. Blood urea nitrogen (BUN), serum creatinine, and urinary N-acetyl-β-d-glucosaminidase (NAG) were used as biochemical markers of MTX-induced renal injury. Our results showed that MTX administration significantly increased BUN, serum creatinine, and urinary NAG levels. The PARP-1 and PAR (a product of PARP activity) expression and apoptotic cell death were also markedly increased in renal tubules after MTX administration. The ISO treatment attenuated MTX-induced renal injury, as indicated by BUN and serum creatinine levels, urinary NAG excretion, and renal histology. The PARP inhibitor treatment reduced PARP-1 and PAR expression to levels similar to that of controls. These results revealed that ISO may have a protective effect against the nephrotoxic effects of MTX by inhibiting PARP activation. This is the first study that demonstrates the role of PARP activation in MTX-induced nephrotoxicity and tubular apoptosis.

Role of opioid receptors in remifentanil-induced attenuation of renal ischemia/reperfusion injury in rats

Objective To investigate the role of opioid receptors in remifentanil-induced attenuation of renal ischemia/reperfusion (I/R) injury in rats.Methods Seventy-five male Sprague-Dawley rats weighing 250-300 g were randomly divided into 5 groups ( n =15 each):sham operation group (group S),group I/R,remifentanil group (group R),naloxone group (group N),and naloxone + remifentanil group (group NR).Renal ischemia was induced by clamping the bilateral renal arteries for 45 min using an atraumatic clamp followed by reperfusion.In groups R and NR,remifentanil was infused at 1.0 μg· kg-1 · min-1 via the caudal vein starting from 15 min before ischemia until 30 min of reperfusion,while groups S,I/R and N received the equal volume of normal saline instead of remifentanil.In groups N and NR,naloxone 0.3 mg/kg was injected via the caudal vein at 20 min before ischemia and at 35 min after ischemia respectively,while groups S,I/R and R received the equal volume of normal saline instead of naloxone.Blood and urine samples were collected from the femoral vein and urinary bladder respectively at 24 h of reperfusion for determination of the levels of serum creatinine (Cr) and blood urea nitrogen (BUN),urinary N-acetyl-β-D-glucosaminidase (NAG) and γ-glutamyl transpeptidase (γ-GT).The rats were sacrificed at 24 h of reperfusion and the renal tissues were removed for determination of nalondialdehyde (MDA) content and superoxide dismutase (SOD) activity.Pathological changes in renal tissues were observed with light microscope.Results Compared withgroup S,the levels of serum Cr and BUN,urinary NAG and γ-GT,and MDA were significantly increased,while the activity of SOD was significantly decreased in the other 4 groups ( P ＜ 0.05 or 0.01 ) and pathological changes in renal tissues were observed in the other 4 groups.Compared with group I/R,the levels of serum Cr and BUN,urinary NAG and γ-GT levels,and MDA were significantly decreased,while the activity of SOD was significantly increased ( P ＜ 0.01 ),and the pathological changes were reduced in group R,and no significant change was found in the parameters mentioned above in groups N and NR ( P ＞ 0.05).The pathological changes were similar in groups I/R,N and NR.Compured with group R,serum Cr and BUN concentrations,urinary NAG and γ-GT levels and MDA concent were increased,while SOD activity were decreased ( P ＜ 0.05 or 0.01 ).Conclusion Opioid receptors mediate remifentanil-induced attenuation of renal I/R injury in rats. Key words: Receptors, opioid; Piperidines; Kidney; Reperfusion injury

Effect of mercury (Hg) dental amalgam fillings on renal and oxidative stress biomarkers in children

We examined the effect of mercury (Hg) associated with dental amalgam fillings on biomarkers of renal and oxidative stress in children between the ages of 5–15.5years. Urine samples were analyzed for N-acetyl-β-d-glucosaminidase (NAG), α1-microglobulin (α1-MG), β2-microglobulin (β2-MG), retinol binding protein (RBP), albumin (ALB), 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). The level of urinary Hg (UHg-C) was calculated as μg/g creatinine. Multiple regression analyses revealed that the excretion of urinary NAG was significantly associated with the presence of dental amalgam fillings (β=0.149, P=0.03) and the levels of UHg-C (β=0.531, P=0), with an interaction between the two (P=0). The increase in urinary NAG in relation to UHg-C levels had a dose–effect pattern. The lowest observed effect was seen at UHg-C levels above 1.452μg/g creatinine, which is lower than previously reported. In contrast, α1-MG was negatively associated with the presence of dental amalgam fillings (β=−0.270, P=0), but positively with UHg-C levels (β=0.393, P=0). There were 7 children without, and one child with, dental amalgam fillings with urinary α1-MG levels above the reference limit of >7mg/g creatinine. Even though α1-MG seems to be a reliable biomarker for early changes in renal functions, it might exert its effect only at a higher level of exposure. An inverse relationship was also observed between urinary 8-OHdG levels and the presence of dental amalgam fillings. This might suggest that the dental amalgam does not increase DNA damage but reduces the capacity to repair DNA, leading to lower urinary excretion of 8-OHdG. On the other hand, we found that Hg affected the excretion of urinary 8-OHdG in a dose-related pattern that was mostly associated with long-term exposure to low Hg levels. Urinary NAG levels were positively associated with urinary MDA levels (β=0.516, P=0) but not with 8-OHdG (β=0.134, P=0.078) after adjustment for potential confounders. Both UHg-C and the presence of dental amalgam fillings remained predictors of the NAG model. Our data provide evidence that low exposure to Hg from dental amalgam fillings exerts an effect on kidney tubular functions in children. Oxidative stress may have played a role in this mechanism. The results of this study would also suggest that urinary NAG is the most sensitive of all the investigated renal biomarkers. These results should be confirmed with further investigation.

Combination of Two Urinary Biomarkers Predicts Acute Kidney Injury After Adult Cardiac Surgery

Urinary L-type fatty acid-binding protein (L-FABP) has not been evaluated for adult post-cardiac surgery acute kidney injury (AKI) to date. This study was undertaken to evaluate a biomarker panel consisting of urinary L-FABP and N-acetyl-β-D-glucosaminidase (NAG), a more established urinary marker of kidney injury, for AKI diagnosis in adult post-cardiac surgery patients. This study prospectively evaluated 77 adult patients who underwent cardiac surgery at 2 general hospitals. Urinary L-FABP and NAG were measured before surgery, at intensive care unit arrival after surgery (0 hours), 4, and 12 hours after arrival. The AKI was diagnosed by the Acute Kidney Injury Network criteria. Of 77 patients, 28 patients (36.4%) developed AKI after surgery. Urinary L-FABP and NAG were significantly increased. However, receiver operating characteristic (ROC) analysis revealed that the biomarkers' performance was statistically significant but limited for clinical translation (area under the curve of ROC [AUC-ROC] for L-FABP at 4 hours 0.72 and NAG 0.75). Urinary L-FABP showed high sensitivity and NAG detected AKI with high specificity. Therefore, we combined these 2 biomarkers, which revealed that this combination panel can detect AKI with higher accuracy than either biomarker measurement alone (AUC-ROC 0.81). Moreover, this biomarker panel improved AKI risk prediction significantly compared with predictions made using the clinical model alone. When urinary L-FABP and NAG are combined, they can detect AKI adequately, even in a heterogeneous population of adult post-cardiac surgery AKI. Combining 2 markers with different sensitivity and specificity presents a reasonable strategy to improve the diagnostic performance of biomarkers.

Effect of Cordyceps sinensis on the expression of HIF-1α and NGAL in rats with renal ischemia-reperfusion injury

To observe the level of urinary neutrophil gelatinase-associated lipocalin (NGAL), the expression of hypoxia inducible factor-1α (HIF-1α) and NGAL in rat kidney after renal ischemia and reperfusion (I/R), before and after the treatment with Cordyceps Sinensis (C. sinensis), and to explore the mechanism of C. sinensis against I/R injury. A total of 45 healthy male Sprague-Dawley rats were randomly divided into a sham group, a renal I/R model group, and a C. sinensis group (15 in each group).The rats in the sham group and the renal I/R model group were intragastrically administered saline (2 mL/d), and rats in the treatment group were intragastricabby administered of C. sinensis [5.0 g/(kg.d)]. The rats were sacrificed at 24, 48, and 72 h, respectively after the reperfusion and urinary N-acetyl-β-D-glucosaminidase (NAG) level was measured, renal function in rats was detected, and the pathological changes were observed with HE staining. We determined the urinary NGAL levels in the rats by ELISA, the expression of HIF-1α mRNA by RT-PCR, and the expressions of HIF-1α and NGAL proteins by confocal immunofluorescence. Compared with the sham group, the levels of BUN, SCr, levels of NAG and NGAL in urine were increased in the I/R group and the C. sinensis group, reached a peak at 24 h after the reperfusion and slowly declined at 48 and 72 h. Glomerular and tubulointerstitial areas in the sham group did not show any pathological change. Induced pathological changes included tubular cell necrosis, focal areas of proximal tubular dilation, distal tubular casts, effacement and loss of proximal tubule brush border, etc. Compared with the sham group, the expression of HIF-1α and NGAL in the kidney tissues of the I/R group and the C. sinensis group increased. C. sinensis can lower the level of NAG and NGAL in the urine and the expression of NGAL protein in the kidney tissues. It up-regulated the expression of HIF-1α mRNA and protein in the kidney tissues whilst attenuated the pathological changes. Renal I/R injury in rats can lead to pathological changes in renal tubular epithelial cells and renal interstitial damage, which are consistent with the pathological features of acute kidney injury (AKI).The level of urinary NAGL increases after the I/R, and positively correlates with the level of urinary NAG and pathological changes, suggesting that urinary NGAL may serve as a urinary biomarker for specific detection of tubular injury in AKI. C. sinensis can attenuate the renal I/ R-induced AKI. Its mechanism may be associated with up-regulating the expression of HIF-1α and down-regulating the expression of NGAL in the kidney tissues.

The Effects of Sevoflurane Anesthesia and Cardiopulmonary Bypass on Renal Function in Cyanotic and Acyanotic Children Undergoing Cardiac Surgery

Background: There are few data on the effects of anesthesia and cardiopulmonary bypass (CPB) on perioperative renal function in children with cyanotic congenital heart disease undergoing open heart surgery. This study aims to investigate the perioperative renal function in cyanotic versus acyanotic children undergoing sevoflurane anesthesia for open heart surgery. Methods: After receiving ethical committee approval, 12 acyanotic patients (preoperative oxygen saturation: SaO2 > 85%) and 12 cyanotic children (SaO2 < 85%) were included. Sevoflurane was administered at concentration levels of 2% before CPB and 1–2% during CPB after standard anesthesia induction. Inorganic fluoride, electrolytes, creatinine, urea nitrogen in serum and urine samples, and N-acetyl-β-d-glucosaminidase (NAG) in urine samples were measured before induction, before CPB, during CPB, after CPB, at the end of surgery, and at 24th h postoperatively. Results: The levels of serum uric acid levels were higher in the cyanotic group (p < 0.05). There were no differences in the levels of serum creatinine and urine creatinine, urea nitrogen, and electrolytes between the two groups. Serum inorganic fluoride levels were always higher in the acyanotic group than in the cyanotic group, but these differences between the groups reached statistical significance at two measurement times (before CPB and end of surgery) (p < 0.05). Urinary inorganic fluoride levels increased with time in both groups. Although urinary NAG increased significantly after the CPB in the cyanotic group, the differences between the two groups did not reach statistical significance. Conclusions: We have concluded that renal function was not affected during open heart surgery with sevoflurane anesthesia, in both cyanotic and acyanotic children.

Ergosta-4,6,8(14),22-tetraen-3-one isolated from Polyporus umbellatus prevents early renal injury in aristolochic acid-induced nephropathy rats

Aristolochic acid (AA) nephropathy, first reported as Chinese herbs nephropathy, is a rapidly progressive tubulointerstitial nephropathy that results in severe anemia, interstitial fibrosis and end-stage renal disease. Tubulointerstitial injury was studied in a rat model of AA nephropathy to determine whether ergosta-4,6,8(14),22-tetraen-3-one (ergone) treatment prevents early renal injury in rats with aristolochic acid I-induced nephropathy. Early renal injury via renal interstitial fibrosis was induced in rats by administration of aristolochic acid I (AAI) solution intragastrically for 8 weeks. Ninety-six rats were randomly divided into four groups (n = 24/group): (1) control (2) AAI (3) AAI + ergone (10 mg/kg) and (4) AAI + ergone (20 mg/kg). Blood and urine samples were collected and rat were sacrificed for histological assessment of the kidneys on at the end of weeks 2, 4, 6 and 8. AAI caused progressive elevation of blood urea nitrogen, creatinine, potassium, sodium, chlorine, proteinuria and urinary N-acetyl-β-D-glucosaminidase (NAG). Ergone suppressed elevation of blood urea, nitrogen, creatinine, proteinuria and urinary NAG to some degree, but the AAI-ergone-treated group did not differ from AAI-treated group for body weight, serum potassium, sodium and chlorine. The progress of the lesions in the kidney after AAI administration was also observed by histopathological examinations, but kidneys from rats of AAI-ergone-treated group displayed fewer lesions. Ergone treatment conferred protection against early renal injury in a rat model of AA nephropathy. Early administration of ergone may prevent the progression of renal injury and the subsequent renal fibrosis in AA nephropathy.

Changes of the tubular markers in type 2 diabetes mellitus with glomerular hyperfiltration

Aim To assess whether glomerular hyperfiltration (GHF) could result in renal tubular damage in type 2 diabetes mellitus (T2DM) patients. Methods Reference value of estimated glomerular filtration rate (eGFR) was determined in 248 healthy individuals based on serum CysC levels. GHF was defined as an eGFR exceeding the sex-specific 97.5th percentile in non-diabetic individuals. In the present study, 30 with GHF, 58 with norm-GFR T2DM, and 24 healthy controls were recruited. Tubular markers, such as urinary N-acetyl-β- d-glucosaminidase (NAG) and kidney injury molecule 1 (KIM-1), as well as serum and urinary neutrophil gelatinase-associated lipocalin (NGAL), were measured and compared. The correlation of these markers with eGFR was analyzed in the GHF group. Results The GHF group had higher urinary NGAL and KIM-1 levels but lower serum NGAL level than the norm-GFR and control groups. Slightly decreased serum NGAL and increased urinary NGAL levels were also noted in the norm-GFR group compared with those of the controls. There was no statistical difference in the urinary NAG values among the three groups. Correlation analysis showed that eGFR was positively related to fasting blood glucose (FBG), HbA1c, urinary NGAL, and KIM-1, but negatively with serum NGAL in the GHF group. Conclusion Higher urinary tubular damage markers were found in T2DM patients with GHF than the norm-GFR and control groups, probably a direct proof that GHF is a deleterious factor for diabetic nephropathy.

Angiotensin-Converting Enzyme Gene Polymorphism and N-Acetyl-β-D-Glucosaminidase Excretion in Endemic Nephropathy

Background: Tubular proteinuria and enzymuria are hallmarks of endemic nephropathy (EN). The role of I/D angiotensin convertase (ACE) gene polymorphism has not yet been elucidated in this peculiar chronic tubulointerstitial nephritis, and our aim was to investigate the role of this polymorphism in EN focusing on the urinary N-acetyl-β-D-glucosaminidase (NAG) excretion, a biomarker of proximal tubular damage. Methods:ACE genotype and allele frequencies were determined in 229 farmers (147 women and 82 men) from an endemic Croatian village. The farmers were stratified according to the WHO criteria into the following subgroups: those ‘at risk’ for EN (n = 37), ‘suspected of having EN’ (n = 57), and ‘others’ (n = 135). Results: There were 74 (32.3%) subjects homozygous for the D allele, 99 (43.2%) heterozygous (ID genotype) and 56 (24.4%) homozygous for the I allele. No differences in allele frequency were found between the established WHO subgroups (p > 0.05). In the whole group, DD subjects had significantly higher values of diastolic blood pressure (p = 0.003) and urinary NAG than subjects with ID and II genotype (5.5 ± 1.2 vs. 4.0 ± 3.0 vs. 3.8 ± 4.2, respectively; p = 0.023). The highest values of serum creatinine (p = 0.02), proteinuria (p = 0.03) and urinary NAG (6.0 ± 3.7 vs. 3.7 ± 2.1 vs. 3.0 ± 1.6, respectively; p = 0.008) were observed in those suspected of having EN group with the DD genotype. Conclusion:ACE gene polymorphism is not a risk factor for EN. However, it might influence the clinical course of EN, and increased excretion of NAG might be a prognostic marker of this chronic tubulointerstitial nephritis.

The dynamics of urinary N-acetyl-β-d-glucosaminidase (NAG), a marker of renal tubular dysfunction, in patients with lupus nephritis undergoing oral prednisone therapy

Introduction and aims: N-Acetyl-β-d-glucosaminidase (NAG), a marker of renal tubular dysfunction, is increased in patients with lupus nephritis. In addition to the toxic effects of proteinuria, patients with lupus nephritis may exhibit other factors that contribute to tubular dysfunction, such as pathogenic antitubular basement membrane antibodies. The aim of our study was to assess urinary NAG, proteinuria, and glomerular filtration rate (GFR) before treatment and after 7 and 30 days of oral prednisone therapy in patients with lupus nephritis.Methods: Ten patients with lupus nephritis, all females, mean age: 29.4 ± 10.17 years, were enrolled into the study. All the patients received oral prednisone 1 mg/kg. Twenty healthy subjects served as controls. We measured urinary NAG before treatment and after 7 and 30 days of oral prednisone therapy. Proteinuria, GFR, blood pressure, and side effects of therapy were also followed up. Urinary NAG was measured using the colorimetrical method and expressed as units per gram of creatinine (U/gCr). Statistical analysis (Wilcoxon signed ranks test and Wilcoxon rank sum test) was performed using SPSS 17.Results: In the 10 patients with lupus nephritis, urinary NAG before treatment was 16.9 ± 13.39 U/gCr (P = 0.005 compared with controls). NAG in controls was 1.73 ± 0.51 U/gCr. Proteinuria before treatment was 3.84 ± 1.93 g/24 h. The GFR before treatment was 50.48 ± 11.98 mL/min/1.73 m2. After 7 days of prednisone, urinary NAG was 23.55 ± 25.25 U/gCr (P = 0.878 compared with baseline, and P = 0.02 compared with controls). Proteinuria was 2.94 ± 1.3 g/24 h (P = 0.005 compared with baseline), and the GFR was 58.11 ± 13.64 mL/min/1.73 m2 (P = 0.005 compared with baseline). After 30 days of prednisone, urinary NAG was 11.77 ± 12.18 U/gCr (P = 0.203 compared with baseline, P = 0.022 compared with the value after 7 days of prednisone, and P = 0.01 compared with controls). Proteinuria was 1.73 ± 0.68 g/24 h (P = 0.005 compared with baseline, and P = 0.005 compared with the value after 7 days of prednisone), and the GFR was 67.49 ± 16.42 mL/min/1.73 m2 (P = 0.005 compared with baseline and P = 0.009 compared with the value after 7 days of prednisone). Blood pressure measurements did not show any significant changes. No major side effects of steroid therapy were noticed.Conclusions: Urinary NAG showed a significant reduction between 7 and 30 days of therapy. The reduction in urinary NAG set in later than the decline in proteinuria and the improvement in GFR. Further studies incorporating a longer follow-up are needed to observe whether the reduction in NAG persists upon continuation of prednisone therapy.

Effects of low-level arsenic exposure on urinary N-acetyl-β-D-glucosaminidase activity

This study was aimed to evaluate whether renal tubular function is impaired by exposure to relatively low concentrations of arsenic. Mean urinary arsenic concentrations and N-acetyl-β-D-glucosaminidase (NAG) activities were compared among 365 and 502 Korean men and women, respectively, in relation to gender, smoking, alcohol consumption, and recent seafood consumption. The study subjects were divided into 4 groups according to urinary NAG activity and seafood consumption prior to urine sampling, and the correlation between arsenic concentration and urinary NAG activity was tested for each group. The mean urinary arsenic level was higher in women, non-smokers, and non-drinkers in comparison to men, smokers, and drinkers, respectively. Individuals who consumed seafood within 3 days prior to urine sampling showed a higher mean urinary arsenic level than those who did not. The correlation between urinary arsenic concentration and NAG activity in urine was significant only in subjects who did not consume seafood within 3 days prior to urine sampling and whose urinary NAG activity was 7.44 U/g creatinine (75th percentile) or higher. The urinary arsenic concentration was a significant determinant of urinary NAG activity in subjects with NAG activity higher than 7.44 U/g creatinine and especially in those who had not consumed seafood recently. These facts suggest that a relatively low-level exposure to inorganic arsenic produces renal tubular damage in humans.

Exercise-induced renal tubular injury in intermittent claudication

While, exercise in intermittent claudication (IC) may improve symptoms and exercise tolerance, it has been shown to produce an ischemia-reperfusion injury. This study aimed to assess the impact of this on renal function, by measuring the changes in activity of the urinary enzyme N-acetyl-β-D-glucosaminidase (NAG), a sensitive marker of renal tubular damage. 15 patients with IC and 15 controls underwent a standardized exercise treadmill test. Changes in Ankle/Brachial Pressure Index (ABPI) were measured as was the urinary activity of NAG at rest, and following exercise. While a marked change was seen in ABPI's of the IC group, no change was apparent in the controls. Urinary NAG activity rose significantly in the IC group following exercise (mean 51.25 µmol/h/mmol creatinine) compared with both resting levels (30.4) and with the post-exercise NAG of controls (26.4),P<0.05. There was no significant difference in NAG levels within the control group (23.5 vs 26.4). Exercise in intermittent claudication is associated with a renal tubular cell injury, which may be related to an ischemia-reperfusion injury.

Urinary proteins, N‐acetyl‐β‐D‐glucosaminidase activity and estimated glomerular filtration rate in hypertensive patients with normoalbuminuria and microalbuminuria

The aim of the study was to assess novel candidate markers measured in the urine of normoalbuminuric and microalbuminuric patients (the urinary albumin-to-creatinine ratio < 30 mg/mmol) with essential hypertension to be used for early detection and assessment of progressive deterioration in renal function. Albumin, α-1-antitrypsin, orosomucoid, transferrin, retinol-binding protein and α-1-microglobulin concentrations and the NAG (N-acetyl-β-D-glucosaminidase) activity in the urine were evaluated in 102 hypertensive subjects with urinary albumin-to-creatinine ratio (uACR) < 30 mg/mmol. The estimated glomerular filtration rate (e-GFR) was calculated using the Modification of Diet in Renal Disease Study equation. The decreasing e-GFR values in normo- and microalbuminuric patients with essential hypertension were accompanied by significant increases (P < 0.05) in the NAG activity and uACR value in the urine. The e-GFR significantly (P < 0.05) correlated with the NAG activity in the urine, but no association was observed with the urinary concentrations of any of the individual proteins (P > 0.05). In normoalbuminuric and microalbuminuric patients with essential hypertension renal impairment measured by e-GFR is related to the increased urinary NAG activity and uACR rather than elevated concentrations of individual proteins. Urinary NAG activity and uACR value seem independently promising candidate markers for use in assessing progression of early renal impairment in patients with hypertension.

Lisinopril attenuates renal oxidative injury in l-NAME-induced hypertensive rats

Hypertension and related oxidative stress are involved in the pathogenesis of any renal diseases. Angiotensin-converting enzyme inhibitors have multi-directional renoprotective effects. In this study, we aimed to investigate whether lisinopril treatment has any biochemical alterations on renal tissue in L-NAME (Nε-nitro-L-arginine methyl ester) induced hypertension model. Twenty-eight Sprague-Dawley rats were included in this study and divided into four equal groups (n = 7): control group, L-NAME treated group (75 mg/kg/day), L-NAME plus lisinopril treated group and only lisinopril treated group (10 mg/kg/day). L-NAME and lisinopril were continued for 6 weeks. Systolic blood pressures were measured by using tail cuff method. In biochemical analysis, malondialdehyde (MDA, an index of lipid peroxidation) levels, the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in renal tissues were used as markers of oxidative stress-induced renal impairment. Microalbumin and N-acetyl-β-D-glucosaminidase (NAG) in urine were determined as markers of renal tubular damage related to hypertension. Chronic L-NAME administration resulted in a significant depletion of serum nitric oxide (NO). When compared with control group, serum creatinine, microalbumin, urine NAG, renal tissue MDA level, and CAT activities were significantly high, while renal tissue SOD and GSH-Px activities low in L-NAME group. In the L-NAME plus lisinopril treated group, serum creatinine, microalbumin and urine NAG, renal MDA level and CAT activity decreased, whereas SOD, GSH-Px activities in renal tissue and serum NO levels were increased. Thus, lisinopril treatment reversed these effects. There were not any significant difference between L-NAME plus lisinopril treated group and control group concerning serum creatinine, renal tissue MDA level and SOD, GSH-Px, CAT activities. These results suggest that lisinopril could diminish biochemical alterations in L: -NAME induced hypertensive renal damage that occurs by oxidative stress.

Does the antiviral therapy of patients with chronic hepatitis exert nephrotoxic effects?

Introduction: HBV and HCV chronic hepatitis can be accompanied by secondary renal disease. In addition, these patients receive antiviral drugs with potential nephrotoxicity. It is known that interferon (IFN) therapy in HCV-infected kidney transplant recipients is followed by rejection of the transplant in 50% of the cases. Ribavirin is contraindicated in hemodialyzed patients and in patients with a GFR <50 ml/min/1.73 m2. IFN therapy requires dosage reduction and close monitoring in patients with a GFR <50 ml/min/1.73 m2 and in patients with end stage renal disease. The aim of our study was to assess the nephrotoxicity of antiviral drugs in patients with chronic hepatitis by measuring three renal biomarkers: urinary albumin, N-acetyl-β-d-glucosaminidase (NAG) and α 1-microglobulin, as well as glomerular filtration rate (GFR-MDRD4) before and at 6 months of therapy.Methods: Fifty-five patients (28 male and 27 female, with a mean age of 47.85 ± 12.03 years) with chronic hepatitis (40 patients with HCV, 13 patients with HBV, 1 patient with HBV+HCV, and 1 patient with HBV+HDV) were enrolled into the study. Different antiviral drug associations were used on a case-by-case basis. The 40 patients with HCV chronic hepatitis received either Peg-IFN-α 2a+Ribavirin (37 patients) or Peg-IFN-α 2b+Ribavirin (3 patients). The 13 patients with HBV chronic hepatitis received Peg-IFN-α 2a (9 patients), Lamivudine (2 patients), Entecavir (1 patient), or Adefovir (1 patient). The patient with HBV+HCV chronic hepatitis received Peg-IFN-α 2a+Ribavirin. The patient with HBV+HDV chronic hepatitis received IFN-α 2a. Urinary albumin (ELISA), NAG (colorimetrical method), α 1-microglobulin (ELISA), and serum creatinine were measured before and at 6 months of antiviral therapy. Urinary markers were expressed as either mg/gCr (for albumin and α 1-microglobulin) or U/gCr (for NAG). Statistical analysis (Pearson’s correlation coefficient, paired t-test and χ2-test) was performed.Results: At 6 months of therapy urinary albumin/gCr did not increase significantly: 16.58 ± 23.39 vs. 15.85 ± 24.96 mg/gCr before therapy, p = 0.87. Urinary NAG/gCr did not increase significantly: 4.21 ± 3.37 vs. 3.83 ± 3.2 U/gCr before therapy, p = 0.53. Urinary α 1-microglobulin/gCr was almost unchanged: 4.38 ± 4.47 vs. 4.38 ± 3.57 mg/gCr before therapy, p = 0.99. The GFR did not decline significantly: 92.41 ± 22.21 vs. 94.59 ± 36.1 ml/min/1.73 m2 before therapy, p = 0.7. Ten patients (18.18%) were albuminuric before therapy, and 14 patients (25.45%) were albuminuric at 6 months of therapy, a non-significant increase (p = 0.35). We found a correlation between urinary albumin/gCr and NAG/gCr and between urinary albumin/gCr and α 1-microglobulin/gCr both at baseline and at 6 months of therapy: r = 0.54, p = 0.0005; r = 0.29, p = 0.03; r = 0.51, p = 0.0005; and r = 0.4, p = 0.002, respectively. In the patient receiving Adefovir, a known nephrotoxic drug, two of the three biomarkers (urinary albumin/gCr and NAG/gCr) increased, most notably NAG/gCr. Both HCV and HBV chronic hepatitis therapy were associated with non-significant changes in renal biomarker excretion and GFR.Conclusions: With the exception of Adefovir, all of the drug associations used in this study were safe.

Regression of microalbuminuria in type 1 diabetes is associated with lower levels of urinary tubular injury biomarkers, kidney injury molecule-1, and N-acetyl-β-D-glucosaminidase

Elevated urinary albumin excretion in patients with type 1 diabetes reverts to normoalbuminuria in a majority of patients but advances toward proteinuria in some. In order to gain valuable insights into the early pathophysiology of diabetic nephropathy we evaluated the association of kidney tubular injury biomarkers with changes in albuminuria in patients with type 1 diabetes mellitus. Urine levels of kidney injury molecule-1 (KIM-1), N-acetyl-β-D-glucosaminidase (NAG), and some inflammatory markers were determined in 38 healthy individuals and 659 patients with type 1 diabetes mellitus having varying degrees of albuminuria. Urinary interleukin-6, CXCL10/IP-10, NAG, and KIM-1 levels were very low in healthy individuals, increased in type 1 patients with normoalbuminuria, and were highest in diabetic patients that had microalbuminuria. Low baseline concentrations of urinary KIM-1 and NAG both individually and collectively were significantly associated with the regression of microalbuminuria over the subsequent 2 years; an effect independent of clinical characteristics. Progression and regression of microalbuminuria were unrelated to urinary levels of interleukins 6 and 8, CXCL10/IP-10, and monocyte chemoattractant protein-1. Thus our results show that lower urinary KIM-1 and NAG levels were associated with the regression of microalbuminuria in type 1 diabetes mellitus. Hence, tubular dysfunction is a critical component of the early course of diabetic nephropathy.

Transcriptional inhibition of progressive renal disease by gene silencing pyrrole–imidazole polyamide targeting of the transforming growth factor-β1 promoter

Pyrrole-imidazole (PI) polyamides are small synthetic molecules that recognize and attach to the minor groove of DNA, thereby inhibiting gene transcription by blocking transcription factor binding. These derivatives can act as gene silencers inhibiting target gene expression under stimulatory conditions such as disease. To evaluate PI polyamides as treatments for the progression of renal diseases, we examined morphological effects, pharmacological properties, and the specificity of PI polyamides targeted to the transforming growth factor (TGF)-β1 promoter during salt-induced hypertensive nephrosclerosis in Dahl salt-sensitive rats. The targeted PI polyamide markedly reduced glomerulosclerosis and interstitial fibrosis without side effects. PI polyamide significantly decreased expression of TGF-β1 and extracellular matrix in the renal cortex. Microarray analysis found that only 3% of the transcripts were affected by PI polyamide, but this included decreased expression of extracellular matrix, TGF-β1-related cytokines, angiogenic, and cell stabilizing factors, proteinases, and renal injury-related factors. Thus, targeted PI polyamides are potential gene silencers for diseases not treatable by current remedies.

Determination of urinary N-acetyl-β-D glucosaminidase (NAG) levels in experimental blunt renal trauma

We evaluated the applicability of urinary N-acetyl-beta-D glucosaminidase (NAG) levels in the diagnosis and follow-up in blunt kidney injury. Twenty Sprague-Dawley rats were studied. In the Sham group, left kidney exploration was made. In the Trauma group, after left kidney exploration, a 20 g weight was dropped onto the kidneys. Urine was collected for analysis with strip and determination of urinary NAG and creatinine (Cr) levels at baseline and 0-6, 12-24, 24-36 and 36-48 postoperative hours. Mann-Whitney U and Kruskal-Wallis tests were used. Macroscopic examinations of traumatized kidneys revealed grade II and III injury, and histopathological examinations showed relevant changes. Macroscopic hematuria was observed in all traumatized rats. Urinary NAG/Cr levels in the Trauma group were found to be significantly higher than their base levels at 0-6, 12-24, 24-36, and 36-48 hours. In the Sham group, only the level of NAG/Cr at 0-6 hours was significantly higher. The increase in NAG/Cr levels at 0-6 hours was significantly higher in the Trauma group than in the Sham group. After isolated blunt renal trauma, urinary NAG levels increase in the early stage. However, more detailed clinical studies are needed to develop NAG levels as a criterion in the follow-up of blunt renal trauma.

Evaluation of the Optimal Frequency of and Pretreatment with Shock Waves in Patients with Renal Stones

PurposeMany studies have been carried out to increase the success rate of shock wave lithotripsy (SWL) and to reduce renal injury. We investigated the success rate after one session as well as urine N-acetyl-β-d-glucosaminidase (NAG) levels for the evaluation of renal injury according to shock wave frequency and pretreatment with low-energy shock waves during SWL.Materials and MethodsThe study targeted 48 patients with renal stones who had undergone SWL. Patients were sequentially allocated into four groups according to shock wave frequency (60 or 120 shocks/min) and whether pretreatment had occurred. We documented total SWL operating number, success rate after first SWL, urine NAG, compliance, and the total cost for each patient.ResultsThere were 32 males and 16 females with an average age of 51.6 years. The average stone size was 7.06 mm, and there was no significant difference in stone size between the groups. The data showed that patients treated with a frequency of 60 shocks/min had a lower mean number of SWL sessions, 1.36 sessions for 60 shocks/min and 2.0 sessions for 120 shocks/min, respectively, which was statistically significant (p<0.05). When comparing NAG/creatinin ratios before and after SWL between those with and without pretreatment, there was no significant difference according to pretreatment (p=0.406).ConclusionsSWL treatment at a frequency of 60 shocks/min yielded better outcomes, such as a lower number of SWL sessions, and had an increased success rate compared with SWL at 120 shocks/min. On the other hand, pretreatment did not impact renal injury. Therefore, SWL treatment at a frequency of 60 shocks/min could improve treatment efficacy more than that for SWL at 120 shocks/min.