Evaluation of renal enzymuria and cellular excretion as an marker of acute nephrotoxicity due to an overdose of paracetamol in Wistar rats

Screening candidate diagnostic biomarkers for diabetic kidney disease

BACKGROUND

There are big differences in treatments and prognosis between diabetic kidney disease (DKD) and non-diabetic renal disease (NDRD). However, DKD patients couldn't be diagnosed early due to lack of special biomarkers. Urine is an ideal non-invasive sample for screening DKD biomarkers. This study aims to explore DKD special biomarkers by urinary proteomics.

MATERIALS AND METHODS

According to the result of renal biopsy, 142 type 2 diabetes mellitus (T2DM) patients were divided into 2 groups: DKD (n = 83) and NDRD (n = 59). Ten patients were selected from each group to define urinary protein profiles by label-free quantitative proteomics. The candidate proteins were further verifyied by parallel reaction monitoring (PRM) methods (n = 40). Proteins which perform the same trend both in PRM and proteomics were verified by enzyme-linked immunosorbent assays (ELISA) with expanding the sample size (n = 82). The area under the receiver operating characteristic curve (AUC) was used to evaluate the accuracy of diagnostic biomarkers.

RESULTS

We identified 417 peptides in urinary proteins showing significant difference between DKD and NDRD. PRM verification identified C7, SERPINA4, IGHG1, SEMG2, PGLS, GGT1, CDH2, CDH1 was consistent with the proteomic results and p < 0.05. Three potential biomarkers for DKD, C7, SERPINA4, and gGT1, were verified by ELISA. The combinatied SERPINA4/Ucr and gGT1/Ucr (AUC = 0.758, p = 0.001) displayed higher diagnostic efficiency than C7/Ucr (AUC = 0.632, p = 0.048), SERPINA4/Ucr (AUC = 0.661, p = 0.032), and gGT1/Ucr (AUC = 0.661, p = 0.029) respectively.

CONCLUSIONS

The combined index SERPINA4/Ucr and gGT1/Ucr can be considered as candidate biomarkers for diabetic nephropathy after adjusting by urine creatinine.

Demonstration of Subclinical Early Nephrotoxicity Induced by Occupational Exposure to Silica among Workers in Pottery Industry

BACKGROUND

For many years, several studies drew attention to the possible nephrotoxic effects of silica and distinct renal dysfunction involving glomerular and renal tubules in workers exposed to silica.

OBJECTIVE

To determine the early signs of subclinical nephrotoxic effects among some Egyptian workers exposed to silica in the pottery industry.

METHODS

This study was carried out in El-Fawakhir handicraft pottery area, in Greater Cairo, Egypt. The studied population included 29 non-smoking male workers occupationally exposed to silica in addition to 35 non-smoking administrative male subjects who represented the comparison group in the study. Measured urinary parameters were concentrations of total protein (TP), microalbumin (Malb), activities of alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT), lactate dehydrogenase (LDH), kidney injury molecule-1 (KIM-1), and silicon (Si).

RESULTS

Silica-exposed workers showed significantly (p<0.05) increased levels of urinary TP, Malb, ALP, γ-GT, LDH, and KIM-1 compared with the comparison group. Among the silicaexposed group, increased urinary Si levels were positively and significantly correlated (Spearman's ρ>0.60, p<0.001 for all variables) with the elevated urinary proteins (including KIM-1) and enzymes levels. All measured urinary parameters were positively and significantly correlated (ρ>0.75, p<0.001 for all variables) with the duration of work among exposed subjects. No significant correlation was observed between the measured variables and the age of workers.

CONCLUSION

There is associated subclinical glomerular and tubular affection among silica exposed workers, which is related to the duration and intensity of exposure.

Reference limits of the urinary gamma-glutamyltransferase in a healthy population and effects of short-term storage on the enzyme activity

BACKGROUND

Gamma-glutamyltransferase (GGT) is present mainly in proximal renal tubule, and urinary GGT is an indicator of tubular damage since it may show renal changes before they are identified by using conventional measurements. Therefore, it is of interest to establish the reference limits of urinary GGT for a healthy population, as well as to investigate the stability of GGT in urine samples stored at 4 °C and -20 °C.

METHODS

GGT was assessed in urine samples from 127 healthy patients by use of a reference method based on the 5-Amino-2-Nitrobenzoate formation. Stability of GGT was evaluated in 10 urine samples stored at temperatures of 4 °C and -20 °C for a period up to 4 weeks.

RESULTS

Urinary GGT values for healthy volunteers were 14 U/g creatinine for the lower reference limit and 79 U/g creatinine for the upper reference limit. Urinary GGT values were approximately 56% lower in samples stored at -20 °C than fresh samples, while samples stored at 4 °C presented a decrease of 11% in GGT values compared to fresh samples.

CONCLUSIONS

Reference limits for urinary GGT in healthy subjects were 14 to 79 U/g creatinine, and it is recommended to measure urinary GGT in fresh specimens.

Evaluation of colistin nephrotoxicity administered at different doses in the rat model

OBJECTIVE

This study evaluated the usefulness of plasma Cystatin C (pCysC) along with urinary neutrophil gelatinase-associated lipocalin (NGAL), γ-glutamyltransferase (GGT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), aspartate (AST) and alanine (ALT) aminotransferase to monitor colistin nephrotoxicity.

METHOD

Male rats were given intramuscular (i.m.) injections of colistin in doses of 150,000 (G1), 300,000 (G2) and 450,000 IU/kg/day (G3) or normal saline (Control), every 12 h for 7 days. After the 14th injection, animals were placed in metabolic cages and urine samples were collected in the next 12 h. Thereafter, animals were euthanized, blood samples were collected and kidneys were removed for histological assessment.

RESULTS

Nephrotoxicity was completely dose-dependent according to pathologic findings. The major insults were acute tubular necrosis in the tubules of G3. No significant change in pCr was observed in all treated groups, but pCysC increased in the G3 compared to the control. In urinary markers, uNGAL level showed a dose dependant increase with significant change in the G2 and G3 groups compared to the control. However, there was no significant change in the AST, ALT, LDH or ALP activities but only GGT increased in the G3 compared to the control.

CONCLUSION

Based on colistin doses used in our experimental study on rat model, histopathologic assessment remains the most accurate way to diagnose colistin nephrotoxicity. pCysC appears to be more reliable than pCr, and uNGAL seems to be the most sensitive factor of colistin nephrotoxicity.

A review of the evidence concerning hepatic glutathione depletion and susceptibility to hepatotoxicity after paracetamol overdose

Paracetamol (acetaminophen) poisoning is common throughout the world. The management of nonstaggered (acute) paracetamol overdose is based on the plasma paracetamol concentration plotted on a treatment nomogram. In the UK there are two treatment lines on this nomogram, with the lower treatment line used for individuals felt to be at ‘high risk’ of paracetamol-related hepatotoxicity either as a result of induction of cytochrome P450 isoenzymes or reduction of intrahepatic glutathione. In this article we review the risk factors that, in current guidelines, are felt to increase risk due to a reduction in intrahepatic glutathione concentrations. Based on our review of the published literature, we feel that cystic fibrosis, acute viral illness, malnutrition, and eating disorders such as anorexia nervosa are likely to be associated with reduction in intrahepatic glutathione concentrations, and that this risk is likely to be related to malnutrition secondary to the disease. Chronic hepatitis C infection is also associated with reduced glutathione concentrations, although this appears to be independent of any associated malnutrition. Ageing and acute fasting are not associated with an increased risk of paracetamol-related hepatotoxicity due to reductions in glutathione concentrations. Finally, the evidence for HIV infection is inconclusive, particularly as the majority of studies were conducted in the pre-anti-viral treatment (HAART) era; however it is likely that patients with symptomatic HIV/AIDS have reduced glutathione concentrations due to associated malnutrition. Although there have been few studies which have specifically investigated whether there is an association between reduced intrahepatic glutathione concentrations and increased risk of paracetamol-related hepatotoxicity, in our opinion, it is likely that the above conditions that are associated with reduced glutathione concentrations, will be associated with an increased risk of paracetamol-related hepatotoxicity.

Enzyme biomarkers of renal tubular injury in arterial surgery patients

OBJECTIVE

The aim of this study was to verify whether preoperative diabetes, hypertension, and renal function had any relationship with postoperative tubule function in patients submitted to anesthesia for arterial surgery.

METHODS

Prospective observational study. One hundred and forty-four patients submitted to anesthesia for arterial surgery enrolled consecutively and divided into four groups: G1--diabetes and hypertension; G2--diabetes; G3--hypertension; and G4--without hypertension or diabetes. Urine was obtained for laboratory analysis of urinary creatinine (Ucr), alkaline phosphatase (AP), γ-glutamyltransferase (γGT), and blood for cystatin C and creatinine before the surgery (M1) and 24 h after the surgery (M2).

RESULTS

Values of γGT, γGT/Ucr, and AP × γGT/Ucr increased at M2 in G4. Patients without renal function compromise (GFR ≥90 mL/min/1.73 m(2)) presented increased γGT/Ucr and AP × γGT/Ucr values at M2 and those with slightly compromised renal function (60-89 mL/min/1.73 m(2)) presented increased γGT values at M2. There was no correlation between deltaCystatin C and deltaAP, deltaγGT, deltaγGT/Ucr, deltaAP/Ucr, and deltaAP × γGT/Ucr.

CONCLUSIONS

Diabetes, hypertension, and preoperative renal function seem to interfere in tubular enzymuria immediately after surgery in arteriopathic patients. However, when these markers do not increase in postoperative period, renal dysfunction cannot be discarded.

Comparison of the effects of N-acetyl cysteine and erdosteine in rats with renal injury caused by paracetamol intoxication

Aim: The aim of the present study was to investigate the therapeutic and preventive effects of N-acetyl cysteine and erdosteine on renal injury associated with paracetamol (acetaminophen) intoxication. Materials and methods: Female albino Wistar rats were divided into six groups: control; paracetamol (1 g/kg, oral); paracetamol (1 g/kg, oral) + erdosteine (150 mg/kg/day, oral); paracetamol (1 g/kg, oral) + N-acetyl cysteine (140 mg/kg bolus, followed by 70 mg/kg, oral); N-acetyl cysteine control (140 mg/kg bolus, followed by 70 mg/kg, oral); and erdosteine control (150 mg/kg/day, oral). Potential renal injury was assessed using biochemical analyses, radionuclide imaging, and histopathological parameters. Results: In the paracetamol group, blood urea nitrogen and creatinine levels were significantly increased compared with controls. Histopathological examination showed tubular vacuolization, tubular necrosis, and remarkable interstitial inflammation. The excretion function was observed to be insufficient on radionuclide imaging. However, in the groups treated with erdosteine or N-acetyl cysteine after paracetamol, biochemical analyses, radionuclide imaging, and histopathological parameters showed significantly less evidence of renal toxicity than that observed in the group receiving paracetamol alone. Less renal toxicity was detected in rats receiving N-acetyl cysteine than in those receiving erdosteine. Conclusion: Renal injury may develop after paracetamol overdose. Erdosteine and N-acetyl cysteine are both effective in the prevention of renal injury when given in the early phase of paracetamol nephrotoxicity. N-acetyl cysteine is more protective than erdosteine.

Evaluation of Subchronic Toxicity of Pet Food Contaminated with Melamine and Cyanuric Acid in Rats

Outbreaks of food-associated renal failure in pets occurred in Asia and the United States of America in 2004 and 2007. They were related to the combined intoxication of cyanuric acid and melamine. Our aims were to investigate cyanuric acid and melamine contamination of pet food and to examine subchronic toxicity in rats. Levels of 10%, 20%, 50%, and 50%–100% (w/w) of contaminated pet food were fed to rats for three months. Analytical results revealed that the tainted food contained significant levels of cyanuric acid and melamine in a ratio of 1:6.8. Rats fed the diet of 50%–100% for three months exhibited elevated serum blood urea nitrogen and creatinine, as well as dose-dependent melamine/cyanuric acid crystal-induced nephrotoxicity. The melamine/cyanuric acid crystals of various sizes were mixed with necrotic cell debris and inflammatory cells, accompanied by tubular dilation and interstitial fibrosis. The immunohistochemistry index of proliferative cellular nuclear antigen and osteopontin in the kidney of the 50%–100% group were elevated, indicating regeneration of renal cells and the formation of crystals. In conclusion, the combination ratio of cyanuric acid to melamine and the acidic urine content were two factors that, upon repeated exposure, determined the severity of the nephrotoxicity.