Obstructed Versus Dilated Nonobstructed Kidneys in Children With Congenital Ureteropelvic Junction Narrowing: Role of Urinary Tubular Enzymes

PURPOSE

We evaluated the role of voided urine lysosomal enzyme N-acetyl-beta-D-glucosaminidase and brush border enzymes alkaline phosphatase and gamma-glutamyl transferase in differentiating between children with ureteropelvic junction obstruction in need of pyeloplasty and those with dilated nonobstructed kidneys suitable for conservative treatment.

MATERIALS AND METHODS

The study included 35 children with unilateral ureteropelvic junction obstruction treated with pyeloplasty (study group) and 15 children with dilated nonobstructed kidneys who were treated conservatively and followed for 15 months (control group). Voided urine samples were obtained before treatment from both groups, and from the study group at 1, 2, 3, 6, 9 and 12 months postoperatively and the control group at 3, 9 and 15 months of followup. N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase were measured in urine samples collected from both groups.

RESULTS

In the study group the activities of preoperative urinary N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase were significantly higher than in the control group. A cutoff value of 7.8 mU/mg creatinine N-acetyl-beta-D-glucosaminidase yielded a sensitivity of 97.1%, a specificity of 80% and an overall accuracy of 92%. A cutoff value of 34.5 IU/gm creatinine alkaline phosphatase resulted in a sensitivity of 91.4%, a specificity of 100% and an overall accuracy of 94%. A cutoff value of 54 IU/gm creatinine gamma-glutamyl transferase yielded a sensitivity of 62.9%, a specificity of 100% and an overall accuracy of 74%. The combination of urinary N-acetyl-beta-D-glucosaminidase and alkaline phosphatase resulted in a sensitivity of 100%, a specificity of 80% and an overall accuracy of 94%. Compared to preoperative activities, N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase decreased significantly at 12 months after pyeloplasty in the study group.

CONCLUSIONS

Voided urinary N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase are accurate markers for differentiating between children with ureteropelvic junction obstruction requiring pyeloplasty and those with dilated nonobstructed kidneys suitable for conservative treatment. Measurement of these enzymes in voided urine could be used as a noninvasive tool for long-term followup of children with ureteropelvic junction obstruction after pyeloplasty and those receiving conservative treatment.

Vancomycin-induced nephrotoxicity in rats: is enzyme elevation a consistent finding in tubular injury?

BACKGROUND

Measurement of urinary enzymes facilitates early detection of acute renal impairment. Since in the case of vancomycin-induced nephrotoxicity, there are different findings for the enzyme N-acetyl-beta-D-glucosaminidase (NAG) in various studies, we decided to measure 3 other important urinary enzymes -- gamma-glutamyl-transferase (GGT), alanine aminopeptidase (AAP) and lactate dehydrogenase (LDH) -- in nephrotoxic rats.

METHODS

Male rats were given intraperitoneal injections of vancomycin (VAN) in doses of 50, 100, 200 and 400 mg/kg or normal saline every 12 hours for 7 days. After the 14th injection, the animals were placed in metabolic cages to collect urine samples.

RESULTS

All animals receiving 400 mg/kg VAN died before completion of treatment course. The nephrotoxicity was completely dose-dependent according to pathologic findings. The major insults were in tubules, resembling acute tubular necrosis. GGT, AAP and LDH activity was measured in urine and corrected by dividing it by urinary creatinine (Cr) concentration. LDH activity showed a dose-dependent increase, while GGT and AAP activity decreased in the 200 mg/kg treated group, but only GGT showed a significant difference with controls. Serum urea and Cr and kidney weights were increased and animals' weights were decreased significantly in the 200 mg/kg VAN group compared with other groups.

CONCLUSION

It seems that pathologic assessment remains the most accurate way to diagnose VAN nephrotoxicity. Changes in urinary enzymes could be not detected in minor tubular injuries; however, LDH appears to be the most sensitive factor. In multiple-dose studies, activity of AAP and GGT seems not to be a reliable index of nephrotoxicity.

Damage of tubule cells in diabetic nephropathy type 2: urinary N-acetyl-beta-D-glucosaminidasis and gamma-glutamil-transferasis

BACKGROUND/AIM

A damage of tubular epithelial cells is followed by the release of cell enzymes and production of proinflammatory compounds, which lead to the tubulointerstitial damage. The aim of this study was to examine the function of renal tubules in the patients with diabetes mellitus type 2 (DM type 2) and the various proteinuria degrees, to establish the damage of the proximal tubule cells caused by DM type 2 by determining urinary N-acetyl-beta-D-glucosaminidasis (beta-NAG) and gamma-glutamil-transferasis (gamma-GT) activity in urine, as well as to compare the obtained results in the examined groups of patients with the values in the healthy examinees.

METHODS

A complete examination of renal function and selective enzymuria was performed in 37 patients with DM type 2, and 14 healthy examinees as the controls. The patients were divided in three groups according to the degree of proteinuria. The first group consisted of the patients with diabetes without microalbuminuria; the second one consisted of the patients with proteinuria of < 300 mg/24 h, and microalbuminuria of > 20 mg/24 h, while the third one included the patients with proteinuria of > 300 mg/24 h.

RESULTS

In the patients with DM type 2 and the preserved global renal function, fractional excretion of sodium, potassium and phosphates, as well as renal threshold of phosphates concentration, were not sensitive parameters for discovering the damage of the renal tubule function. The determination of beta-NAG activity proved to be the most sensitive parameter for early discovering of tubule cells damages. The difference among the examined groups was statistically highly significant.

CONCLUSION

The increased presence of beta-NAG in the urine of DM type 2 patients, pointed out an early tubular disorder and damage of cells, while gamma-GT was a less sensitive indicator of this damage.

S-(1,2,2-Trichlorovinyl)-l-cysteine Sulfoxide, a Reactive Metabolite ofS-(1,2,2-Trichlorovinyl)-l-cysteine Formed in Rat Liver and Kidney Microsomes, Is a Potent Nephrotoxicant

Previously, we have provided evidence that cytochromes P450 (P450s) and flavin-containing monooxygenases (FMOs) are involved in the oxidation of S-(1,2,2-trichlorovinyl)-L-cysteine (TCVC) in rabbit liver microsomes to yield the reactive metabolite TCVC sulfoxide (TCVCS). Because TCVC is a known nephrotoxic metabolite of tetrachloroethylene, the nephrotoxic potential of TCVCS in rats and TCVCS formation in rat liver and kidney microsomes were investigated. At 5 mM TCVC, rat liver microsomes formed TCVCS at a rate nearly 5 times higher than the rate measured with rat kidney microsomes, whereas at 1 mM TCVC only the liver activity was detectable. TCVCS formation in liver and kidney microsomes was dependent upon the presence of NADPH and was inhibited by the addition of methimazole or 1-benzylimidazole, but not superoxide dismutase, catalase, KCN, or deferoxamine, consistent with the involvement of both FMOs and P450s. Rats given TCVCS at 230 micromol/kg i.p. exhibited acute tubular necrosis at 2 and 24 h after treatment, and they had elevated blood urea nitrogen levels at 24 h, whereas TCVC was a much less potent nephrotoxicant than TCVCS. Furthermore, pretreatment with aminooxyacetic acid enhanced TCVC toxicity. In addition, reduced nonprotein thiol concentrations in the kidney were decreased by nearly 50% 2 h after TCVCS treatment compared with saline-treated rats, whereas the equimolar dose of TCVC had no effect on kidney nonprotein thiol status. No significant lesions or changes in nonprotein thiol status were observed in liver with either TCVC or TCVCS. Collectively, the results suggest that TCVCS may play a role in TCVC-induced nephrotoxicity.

Are 4-hydroxy-2(E)-nonenal derived mercapturic acids and 1H NMR metabonomics potential biomarkers of chemically induced oxidative stress in the kidney?

Various markers derived from radical-mediated oxidative damage to cellular macromolecules have been proposed as tools for the detection of alterations in redox status, but there is strong debate as to which may be the most sensitive and reliable indicator of oxidative stress conditions. This study was aimed to investigate the use of mercapturic acids derived from conjugation of the lipid peroxidation product 4-hydroxy-2(E)-nonenal (HNE) with glutathione and (1)H NMR metabonomics in two rodent models of oxidative kidney damage. Treatment of rats with FeNTA resulted in a marked increase in the concentrations of 4-hydroxy-2(E)-nonenal derived mercapturic acids in plasma and kidney within 5h. 1,4-dihydroxynonenal mercapturic acid (DHN-MA) remained elevated 24h after compound administration, while other markers returned to control levels, suggesting that DHN-MA may present a more stable indicator of lipid peroxidation. However, significant changes were only evident in the presence of severe nephrotoxicity, indicating that HNE-derived mercapturic acids were less sensitive than nonspecific markers of renal injury. In contrast to FeNTA, continuous administration of potassium bromate for 2 weeks had no effect on the concentrations of DHN-MA or 4-hydroxyononenal-3-yl-mercapturic acid in kidney, plasma or urine of treated animals, although a dose-dependent increase in 8-oxo-7,8-dihydro-2'deoxyguanosine was observed in kidney DNA in the absence of nephrotoxicity. These data suggest that markers of lipid peroxidation may not be suitable to detect alterations in redox status induced by potassium bromate at doses known to cause tumors after chronic treatment. Alterations in urine (1)H NMR spectra were detected in both models but reflect nonspecific alterations as a result of impaired renal function rather than specific changes indicative of oxidative stress. In summary, it appears that - depending on the pathological circumstances and the chemical nature of the insult - different types of oxidative stress exist, and it is therefore not possible to define a universal marker of oxidative stress.

The effect of 2,3-dihydroxybenzoic acid and tempol in prevention of vancomycin-induced nephrotoxicity in rats

One of the major adverse effects of vancomycin (VAN) is nephrotoxicity, which the mechanism is not fully understood. However, there is some evidence that oxidative injury could be involved in its pathogenesis. In this study, we examined two antioxidants 4-hydroxyl-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol) a superoxide dismutase mimetic and 2,3-dihydroxybenzoic acid (DHB) an iron chelator in VAN-induced nephrotoxicity in rats. DHB at doses of 50 and 100 mg/kg and tempol at doses of 7.5, 15 and 30 mg/kg were administered subcutaneously to rats 30 min prior to intraperitoneal injection of 200 mg/kg VAN. Drug administrations were done every 12 h for 7 days. In animals which received only VAN, the activity of urinary gamma-glutamyl-transferase (GGT) decreased and the activity of lactate dehydrogenase (LDH) in urine increased significantly compared to controls. Serum urea and creatinine (Cr) concentrations and the weight of animals' kidneys increased and body weights were decreased significantly in this group compared to controls. DHB at both doses normalized the GGT activity, but only at the higher dose restore the LDH activity. Both doses of DHB ameliorated the rise in serum urea and Cr concentrations and improved the changes in kidney and body weights significantly. Tempol did not show any beneficial effects at all. There were marked pathologic changes in tubules of kidneys of VAN treated animals. The tissue injury was prevented by both doses of DHB and there was almost no sign of tubular injury in 100 mg/kg treated group. Tempol in any doses could not prevent the tissue injury and there were significant differences in tissue injury in all tempol treated rats with controls. It seems that VAN-induced nephrotoxicity is at least partly due to free radical formation. Hydroxyl radicals might play a major role in VAN-induced nephrotoxicity, since an iron chelator (DHB) could reverse the adverse effects. However, production of other radicals such as superoxide is also probable.

The Interaction between Orally Administered Non-Steroidal Anti-Inflammatory Drugs and Prednisolone in Healthy Dogs

The interaction between oral non-steroidal anti-inflammatory drugs (NSAIDs) and prednisolone administered concurrently for 30 days was studied in 18 healthy dogs divided into 3 groups of 6 dogs each: a drug-free negative control group (NC group) given 2 gelatin capsules; a group given meloxicam (0.1 mg/kg) and prednisolone (0.5 mg/kg) (MP group); and a group given a reduced dosage of ketoprofen (0.25 mg/kg, p.o.) and prednisolone (0.5 mg/kg, p.o.) (KP group). The dogs were periodically monitored by physical examinations, blood analyses, endoscopic examinations, fecal occult blood tests, renal function tests [effective renal plasma flow (ERPF) and glomerular filtration rate (GFR)], urinalyses [urinary sediments, and urinary micro-albumin to creatinine ratio (UAlb/Cre)], urinary enzyme indices, and haemostatic function tests [buccal mucosa bleeding time (BMBT), cuticle bleeding time (CBT)]. Significant changes were observed in the KP group, including a decrease of ERPF and GFR, an increased UAlb/Cre ratio, prolonged BMBT and CBT, as well as the presence of more severe grades of endoscopic lesions and fecal occult blood. In both the MP and KP groups, abnormal enzymuria with exfoliation of renal tubular epithelial cells in the urine was found. However, no significant changes in any of the other tests were observed in the MP group compared with the NC group. These findings suggest that the combination of NSAIDs, even selective COX-2 inhibitors, with prednisolone may be contraindicated due to the potential for serious adverse effects on the kidneys, the platelets, and the gastrointestinal tract.

Dose-effect relationship between drinking water fluoride levels and damage to liver and kidney functions in children

Although a dose-effect relationship between water fluoride levels and damage to liver and kidney functions in animals has been reported, it was not demonstrated in humans. To evaluate the effects of drinking water fluoride levels on the liver and kidney functions in children with and without dental fluorosis, we identified 210 children who were divided into seven groups with 30 each based on different drinking water fluoride levels in the same residential area. We found that the fluoride levels in serum and urine of these children increased as the levels of drinking water fluoride increased. There were no significant differences in the levels of total protein (TP), albumin (ALB), aspartate transamine (AST), and alanine transamine (ALT) in serum among these groups. However, the activities of serum lactic dehydrogenase (LDH), urine N-acetyl-beta-glucosaminidase (NAG), and urine gamma-glutamyl transpeptidase (gamma-GT) in children with dental fluorosis and having water fluoride of 2.15-2.96 mg/L and in children having water fluoride of 3.15-5.69 mg/L regardless of dental fluorosis were significantly higher than children exposed to water fluoride of 0.61-0.87 mg/L in a dose-response manner. In contrast to children with dental fluorosis and having water fluoride of 2.15-2.96 and 3.10-5.69 mg/L, serum LDH activity of children without dental fluorosis but exposed to the same levels of water fluoride as those with dental fluorosis were also markedly lower, but the activities of NAG and gamma-GT in their urine were not. Therefore, our results suggest that drinking water fluoride levels over 2.0mg/L can cause damage to liver and kidney functions in children and that the dental fluorosis was independent of damage to the liver but not the kidney. Further studies on the mechanisms and significance underlying damage to the liver without dental fluorosis in the exposed children are warranted.

Effects of selenium and zinc on renal oxidative stress and apoptosis induced by fluoride in rats

OBJECTIVE

To study the effects of selenium and zinc on oxidative stress, apoptosis, and cell cycle changes in rat renal cells induced by fluoride.

METHODS

Wistar rats were given distilled water containing sodium fluoride (50 mg/L NaF) and were gavaged with different doses of selenium-zinc preparation for six months. Four groups were used and each group had eight animals (four males and four females). Group one, sham-handled control; group two, 50 mg/L NaF; group three, 50 mg/L NaF with a low dose of selenium-zinc preparation (0.1 mg/kg Na2 SeO3 and 14.8 mg/kg ZnSO4 x 7H2O); and group four, 50 mg/L NaF with a high dose of selenium-zinc preparation (0.2 mg/kg Na2 SeO3 and 29.6 mg/kg ZnSO4 x 7H2O). The activities of serum glutathione peroxidase (GSH-Px), kidney superoxide dismutase (SOD), and the levels of malondialdehyde (MDA) and glutathione (GSH) in the kidney were measured to assess the oxidative stress. Kidney cell apoptosis and cell cycle were detected by flow cytometry.

RESULTS

NaF at the dose of 50 mg/L increased excretion of fluoride in urine, promoted activity of urine gamma-glutamyl transpeptidase (gamma-GT), inhibited activity of serum GSH-PX and kidney SOD, reduce kidney GSH content, and increased kidney MDA. NaF at the dose of 50 mg/L also induced rat renal apoptosis, reduced the cell number of G2/M phase in cell cycle, and decreased DNA relative content significantly. Selenium and zinc inhibited effects of NaF on oxidative stress and apoptosis, promoted the cell number of G2/M phase in cell cycle, but failed to increase relative DNA content significantly.

CONCLUSION

Sodium fluoride administered at the dose of 50 mg/L for six months induced oxidative stress and apoptosis, and changes the cell cycle in rat renal cells. Selenium and zinc antagonize oxidative stress, apoptosis, and cell cycle changes induced by excess fluoride.

Urinary gamma-glutamyltransferase (GGT) as a potential marker of bone resorption

We recently identified gamma-glutamyltransferase (GGT) as a novel bone-resorbing factor. The present study was undertaken to determine whether GGT is a marker of bone resorption in two genetic models of hyper- and hypo-function of osteoclasts, as well as in postmenopausal women with accelerated bone resorption, using type I collagen N-telopeptide (NTX) and deoxypyridinoline (DPD) as established biochemical markers. Urinary excretion of GGT, corrected for creatinine, was found to be increased in osteoprotegerin (OPG)-deficient osteoporotic mice as well as in patients with postmenopausal osteoporosis (67-83 years of age); in both cases the urinary level decreased after treatment of patients or mice with alendronate, a selective inhibitor of bone resorption, concomitantly with a reduction in DPD and NTX. Conversely, in osteopetrotic op/op mice, urinary GGT increased in parallel with DPD after induction of osteoclasts with M-CSF injection. Constant infusion of parathyroid hormone (PTH) also increased urinary GGT along with DPD. In a survey of 551 postmenopausal women (50-89 years of age) at their regular health checkup, urinary GGT excretion exhibited a high correlation with DPD (rho = 0.49, p < 0.0001). The calculated sensitivity and specificity for diagnosing elevated bone resorption, as determined by a DPD value higher than 7.6 nM/mM Cr, were 61% and 92%, respectively, when a cut-off value of 40 IU/g Cr was assigned for urinary GGT. Since GGT activity can be measured inexpensively in large numbers in a very short time, the measurement of urinary level may provide a convenient and useful method for mass screening to identify those with increased bone turnover and hence at increased risk for bone fracture.

The effect of exercise on urinary gamma-glutamyl transferase and protein levels of volleyball players

AIM

Postexercise proteinuria and increased urinary gamma-glutamyl transferase (GGT) levels can be indicative of exercise-induced renal damage. In the literature, there exists numerous studies on exercise-induced proteinuria; but studies investigating the effects of exercise on urinary GGT levels are quite few. We aimed to evaluate the effects of exercise on renal function, expressed through the exercise-induced differences in urinary GGT, creatinine and protein levels.

METHODS

The study was performed on 12 female and 12 male volleyball players of the same sports club. Urine samples collected before and 1 h after the exercise were analyzed for urinary GGT, creatinine and protein amounts.

RESULTS

No statistically significant difference was observed between pre- and postexercise urinary GGT levels (U/L and U/g creatinine) of female and male volleyball players (P>0.05). A significant exercise-induced increase in urinary protein excretion was observed for the male players, while a significant exercise-induced increase in urinary creatinine excretion was observed for the female players (P<0.05). When urinary GGT levels (U/L) were compared separately for setters and spikers, it was observed that female players had no significant difference, while male spikers had a statistically significant exercise-induced increase in the urinary GGT levels (U/L) (P<0.05).

CONCLUSIONS

We suggest that the insignificance of the exercise-induced increases in the urinary parameters could be due to the relatively short-course of the exercise and the timing of postexercise urine collection. A comprehensive study performed on more subjects could yield results that are more significant.

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

INTRODUCTION

The present study was conducted to determine whether the urinary levels of excreted enzymes, gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), aspartate (AST) and alanine aminotransferases (ALT), can efficiently indicate, within 24 h, an acute nephrotoxicity due to an overdose of paracetamol (PAR).

METHODS

A baseline urine was collected from the experimental group. Thereafter, blood collected from the orbital sinus (1.0 ml) and paracetamol (650 mg/kg of body weight) was administered by gavage. After the drug administration, animals were returned to the metabolic cages and then urine was collected in the next 22 h. Blood and urine collection was performed at time 0+24 h (T(24)), as well as at times 48 and 72 h (T(48) and T(72)). After the last urine and blood collection, the rats were killed and the kidneys removed and prepared for histological examination. Plasma creatinine and urinary levels of creatinine (to determinate glomerular filtration rate-GFR), GGT, ALP, LDH, ALT and AST were measured. Kidney tissues were stained with hematoxylin and eosin stain for histological assessment.

RESULTS

Urinary levels of GGT, ALP and LDH enzymes were significantly higher (P<0.05) at T(24) when compared to the levels at T(0) and returned to basal levels at T(48) and T(72). The number of urinary epithelial cells at T(24) was significantly higher when compared to the control time (T(0)) (P<0.001). The GFR was significantly reduced 24, 48 and 72 h after the drug administration.

CONCLUSION

The number of urinary epithelial cells and urinary enzymes levels are a simple and low cost procedure that is available and can help in the detection of renal acute lesions.

Biologically variable bypass reduces enzymuria after deep hypothermic circulatory arrest

BACKGROUND

Renal injury is common after open-heart surgery. Cardiopulmonary bypass contributes to the problem. We compared conventional nonpulsatile perfusion (NP) to biologically variable perfusion (BVP), which uses a computer controller to restore physiological beat-to-beat variability to roller pump flow. We hypothesized BVP would decrease renal injury after deep hypothermic circulatory arrest.

METHODS

Pigs were randomly assigned to either BVP (n = 9) or NP (n = 9), cooled, arrested at 18 degrees C (1 hour), reperfused, and rewarmed and maintained normothermic (3 hours). Additional pigs had NP for a similar time as above, but without circulatory arrest (n = 3), or were sham-treated without bypass (n = 3). Hemodynamics, acid-base status, temperature, and urine volumes were measured. Urinary enzyme markers of tubular injury were compared post-hoc for gamma glutamyl transpeptidase, alkaline phosphatase, and glutathione S-transferase and by urine proteomics using mass spectrometry.

RESULTS

Urine output at 1 hour after arrest was 250 +/- 129 mL with BVP versus 114 +/- 66 mL with NP (p < 0.02). All three renal enzyme markers were higher with NP after arrest compared with BVP. In animals on bypass without arrest or those sham-treated, no elevations were seen in renal enzymes. Urine proteomics revealed abnormal proteins, persisting longer with NP. Biologically variable perfusion decreased cooling to 21.0 +/- 9.0 minutes versus 31.7 +/- 7.5 minutes (p < 0.002), and decreased rewarming to 22.1 +/- 3.9 minutes versus 31.2 +/- 5.1 minutes (p < 0.002).

CONCLUSIONS

Biologically variable perfusion improved urine output, decreased enzymuria, and attenuated mass spectrometry urine protein signal with more rapid temperature changes. This strategy could potentially shorten bypass duration and may decrease renal tubular injury with deep hypothermic circulatory arrest.

Excretion of urinary enzymes in normal pregnancy

OBJECTIVES

To study the pattern of excretion of enzymes in urine during normal pregnancy.

DESIGN AND METHODS

Primigravidae, with uncomplicated pregnancies, were followed up throughout gestation. Urine samples were collected from them and activities of alanine aminopeptidase (AAP), gamma-glutamyl transferase (GGT), acid phosphatase (ACP) and N-acetyl-beta-d-glucosaminidase (NAG) activities in urine were estimated.

RESULTS

Small but significant increases were found in the activities of AAP and NAG excreted through the course of pregnancy. The changes seen in excretion of ACP and GGT were not statistically significant.

CONCLUSIONS

Changes in excretion of ACP and GGT may be useful indicators of renal dysfunction in pregnancy, as their activities did not vary significantly through the course of normal pregnancy.

Kidney Toxicity of Ingested Uranium From Drinking Water

BACKGROUND

In experimental settings, uranium is toxic to kidneys, but effects on humans are unclear. Ingestion of water from drilled wells is a source of high uranium exposure in some populations.

METHODS

Uranium exposure was measured in 95 men and 98 women aged 18 to 81 years who had used drinking water from drilled wells for an average of 16 years. Urinary N-acetyl-gamma-d-glucosaminidase, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyltransferase, and glutathione-S-transferase; serum cystatin C; and urinary and serum calcium, phosphate, glucose, and creatinine were measured to evaluate possible toxic effects of uranium on kidney cells and renal function. In addition, supine blood pressure was measured. Associations between uranium exposure and the outcome variables were modeled by using linear regression with adjustment for age, sex, body mass index, smoking, and analgesic use.

RESULTS

Median uranium concentration in drinking water was 25 microg/L (interquartile range, 5 to 148 microg/L; maximum, 1,500 microg/L). Indicators of cytotoxicity and kidney function did not show evidence of renal damage. No statistically significant associations with uranium in urine, water, hair, or toenails was found for 10 kidney toxicity indicators. Uranium exposure was associated with greater diastolic and systolic blood pressures, and cumulative uranium intake was associated with increased glucose excretion in urine.

CONCLUSION

Continuous uranium intake from drinking water, even at relatively high exposures, was not found to have cytotoxic effects on kidneys in humans.

[The nephrotoxicity in rats caused by Longdan Xiegan decoction]

OBJECTIVE

To observe the renal injury in rats induced by Longdan Xiegan decoction (LDXGD) containing different dosages Aristolochia manshriensis.

METHOD

SD rats were divided into four groups at random, and were fed with three kinds of LDXGD 13, 14.5, 17.5 g x kg(-1) (containing respectively A. manshriensis 1.5, 3, 6 g x kg(-1)) and distilled water respectively for 12 weeks. Renal functional parameters on 4,8,12 w were determined and changes of histomorphology in rats on the end of experiment were observed.

RESULT

The LDXGD containing low dose (1.5 g x kg(-1)) A. manshriensis did't induce significantly renal injury in rats during 12 weeks; the LDXGD containing midst dose(3 g x kg(-1)) A. manshriensis induced light damage of proximal convoluted tubule epithelial cells in rats during 12 weeks; the LDXGD containing high dose(6 g x kg(-1)) A. manshriensis induced significantly renal injury in rats after administed 4 weeks. Along with the lasting of administration, the degree of injury became more seriously. The main renal injury location was in proximal convoluted tubule.

CONCLUSION

The renal toxicity of LDXGD is correlated with the dose of A. manshriensis and the time of administration. The LDXGD containing low dose A. manshriensis has relative security. However, the LDXGD containing high dose A. manshriensis can induce renal injury.

Effects of Green Tea on Urinary Stone Formation: An in Vivo andin VitroStudy

PURPOSE

We evaluated whether epigallocatechin gallate (EGCG), a main constituent of green tea polyphenols, could protect against cellular toxicity by oxalate and whether green tea supplementation attenuates the development of nephrolithiasis in an animal model.

MATERIALS AND METHODS

Cells of the NRK-52E line were incubated with different concentrations of oxalate with and without EGCG, and toxicity and malondialdehyde assays were done to investigate the cytotoxic effect of oxalate and the anti-oxalate effect of EGCG.. In a second series of experiments, male Sprague-Dawley rats were divided into three groups. Group 1 animals (controls) were fed regular chow and drank water ad libitum; group 2 animals were fed chow containing 3% sodium oxalate with the administration of gentamicin (40 mg/kg) and drank water ad libitum; group 3 animals were fed the same diet as group 2 with gentamicin administration and drank only green tea. Rats were killed 4 weeks later after a 24-hour urine collection, and the kidneys were removed for morphologic examination.

RESULTS

As oxalate concentrations increased, the number of surviving cells decreased, and the formation of free radicals increased. The administration of EGCG inhibited free-radical production induced by oxalate. Green tea supplementation decreased the excretion of urinary oxalate and the activities of urinary gammaglutamyltranspeptidase and N-acetylglucosaminidase. The number of crystals within kidneys in group 3 was significantly lower than in group 2.

CONCLUSIONS

Green tea has an inhibitory effect on urinary stone formation, and the antioxidative action of EGCG is considered to be involved.

[Selected biochemical parameters of urine in the evaluation of paracetamol nephrotoxicity]

A multitude of paracetamol synonyms, its common application in multidrug treatment, general availability contribute to frequent abuse of this drug. Recently observed increase in the number of suicide attempts with paracetamol is disturbing. Detailed clinical analysis of patients after intake of toxic doses of paracetamol revealed, apart from hepatotoxicity, cases of acute renal failure. Thus there is a need to search for sensitive indicators enabling early detection of nephrotoxic effects resulting from toxic doses of paracetamol.

MATERIAL AND METHODS

Material for research was urine and blood serum collected in a few successive days from 8 patients (6 female, 2 male) aged from 16 to 32 years old after single intake of paracetamol for suicidal purposes. The dose of taken paracetamol amounted on average to 17.8 gram. The control group consisted of 21 healthy individuals. Specific biochemical indicators marking proximal tubules were assessed--glutathione transferase-alpha (alpha-GST), distal tubular--glutathione transferase-pi (pi-GST), lysosomes: N-acetylbeta-D-glucosaminidase (NAG), iso-enzyme (NAG-B), beta-galactosidase (betaGAL), beta-glucuronidase (beta-Gr); brush border: alanine aminopeptidase (AAP), gamma-glutamyltransferase (GGT) as well as the efficiency of nephron resorption process through concentration of beta2-microglobulin (beta2M) in urine and its filtracy fraction of elimination. Moreover, the levels of free sialic acids, which in higher concentrations point to disturbances in glomerular filtration, were evaluated.

RESULTS AND CONCLUSIONS

Acute kidney failure was found in none case. However, transient increase in NAG, NAG-B, alpha-GST, beta-Gr, GGT and beta2M enzymes was observed. On the basis of performed investigations it may be assumed that the determination of these parameters in urine will enable early detection of changes in the kidneys occurring under the influence of toxic doses of paracetamol and prevent their further development due to appropriate therapeutic management.

Alterations in the biochemical markers of renal function after sevoflurane anaesthesia

AIM

This study has been carried out to see whether renal function is acutely altered in patients undergoing sevoflurane anaesthesia. For this purpose, the urinary levels of markers of renal tubular function, namely leucine amino peptidase (LAP), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and beta-2 microglobulin (beta-2M), and urinary albumin as a predictor of renal glomerular function were measured before and after sevoflurane anaesthesia.

METHODS

This study was comprised of 20 patients (11 males and nine females) aged 18-55, who underwent various elective surgical procedures under general anaesthesia. Urine samples of all patients were collected before and 1, 2 and 8 h after the anaesthesia. The levels of LAP, GGT, beta-2M, and albumin were then expressed as factored by urinary creatinine. In all patients, the anaesthesia was maintained with sevoflurane (2% end-tidal) at a high flow-rate (6 L/min).

RESULTS

Urinary beta-2M and LAP levels after anaesthesia were unchanged (P > 0.05). While urinary GGT and ALP levels were found elevated in the first hour, LDH levels were higher in the second hour (P < 0.05). They returned to normal levels in the later periods after the anaesthesia. Urinary albumin excretion (UAE) was significantly elevated in the second hour after the anaesthesia (P < 0.001). Although UAE was decreased in the eighth hour after the anaesthesia, it still remained higher than the pre-anaesthesia level (P < 0.001).

CONCLUSIONS

These results suggest that a 2% end-tidal concentration of sevoflurane at a high flow-rate (6 L/min) acutely alters renal glomerular function but does not have a significant acute effect on biochemical markers of renal tubular damage.

Toxicity, pathophysiology and pathology in sheep following dosing of the nephrotoxic plant Nolletia gariepina (DC) Mattf

Ingestion of the plant Nolletia gariepina was confirmed as the cause of acute mortalities in cattle in the Kuruman area of the Northern Cape Province of South Africa. The aim of this trial was to investigate the toxic effects of this plant with respect to clinical signs, pathophysiology and pathology using the sheep as a model. At dosages of 1.5 g dried, milled plant material/kg body mass there were no detectable abnormal findings, while at dosages of 2.8-3.0 g/kg most of the animals died acutely. In subacutely affected sheep, depression, inappetance, teeth grinding, tachycardia, weak ruminal movements and recumbency were noticed. The most prominent pathophysiological changes observed, included a sharp rise in non-protein nitrogen substances in the plasma, remarkable decline in glomerular filtration rate, increase in sodium and potassium excretion, and a rise in urine gamma glutamyltransferase activity. Macroscopically a severe nephrosis was present in all the animals. The most important findings detected histologically were necrosis of the proximal convoluted tubular epithelium and large numbers of protein casts in the lumens.

Urinary GGT/creatinine ratio and fractional excretion of electrolytes in diarrhoeic calves

The aim of this study was to monitor renal function in diarrhoeic calves and to determine the effectiveness of an applied fluid therapy. A total of 28 diarrhoeic (n = 18) and healthy (n = 10) Holstein-Friesian calves of different sexes, between 1 and 30 days of age, were used. Blood and urine samples were obtained from diarrhoeic calves before the treatment and then three more times at 24-h intervals during the treatment. From healthy calves, samples were taken only once. Therapy was started by the intravenous administration of 8.4% sodium bicarbonate and 0.9% sodium chloride solutions for the first 24 h, followed by the oral application of a commercial electrolyte solution (sodium chloride 3.5 g, trisodium citrate 2.9 g, potassium chloride 1.5 g and glucose anhydrous 20 g in 1 litre H2O) up to the 48th h of therapy. Before the therapy, the average levels of pH (7.10 +/- 0.12), bicarbonate (HCO3-) (16.48 +/- 3.80 mmol/l), base deficit (-12.65 +/- 5.97 mmo/l) and fractional excretion (FE) of sodium (0.16 +/- 0.11%) and potassium (15.07 +/- 8.56%) were significantly lower while serum urea (17.48 +/- 10.32 mmol/l) and creatinine (Cr) concentrations (169.72 +/- 98.12 micromol/l), haematocrit levels (45.13 +/- 13.60%) and urinary gamma glutamyl transferase (GGT)/Cr ratio (8.6 +/- 4.3 x 1/10(3) U/micromol) were significantly higher in diarrhoeic calves than in healthy calves. Alterations in parameters indicating the presence of renal dysfunction were normalised in the diarrhoeic calves that survived (83.3%). Three calves with severe metabolic acidosis and azotaemia died at the beginning of therapy. It was concluded that the FE of Na and K (FENa, FEK) and urine GGT/Cr ratio may have an important role in assessing renal function in diarrhoeic calves and in evaluating the effectiveness of an applied fluid therapy.

Prophylactic role of phycocyanin: a study of oxalate mediated renal cell injury

Oxalate induced renal calculi formation and the associated renal injury is thought to be caused by free radical mediated mechanisms. An in vivo model was used to investigate the effect of phycocyanin (from Spirulina platensis), a known antioxidant, against calcium oxalate urolithiasis. Male Wistar rats were divided into four groups. Hyperoxaluria was induced in two of these groups by intraperitoneal infusion of sodium oxalate (70 mg/kg) and a pretreatment of phycocyanin (100 mg/kg) as a single oral dosage was given, 1h prior to sodium oxalate infusion. An untreated control and drug control (phycocyanin alone) were also included in the study. We observed that phycocyanin significantly controlled the early biochemical changes in calcium oxalate stone formation. The antiurolithic nature of the drug was evaluated by the assessment of urinary risk factors and light microscopic observation of urinary crystals. Renal tubular damage as divulged by urinary marker enzymes (alkaline phosphatase, acid phosphatase and gamma-glutamyl transferase) and histopathological observations such as decreased tubulointerstitial, tubular dilatation and mononuclear inflammatory cells, indicated that renal damage was minimised in drug-pretreated group. Oxalate levels (P < 0.001) and lipid peroxidation (P < 0.001) in kidney tissue were significantly controlled by drug pretreatment, suggesting the ability of phycocyanin to quench the free radicals, thereby preventing the lipid peroxidation mediated tissue damage and oxalate entry. This accounts for the prevention of CaOx stones. Thus, the present analysis revealed the antioxidant and antiurolithic potential of phycocyanin thereby projecting it as a promising therapeutic agent against renal cell injury associated kidney stone formation.

A comparison of methods for measuring serum and urinary markers of bone metabolism in cats

Biochemical markers of bone cell activity have recently been shown to be useful for monitoring skeletal health in domestic animals, including dogs and horses. The aim of this study was to evaluate a number of biochemical assays, originally developed for use in humans, for their ability to measure indicators of bone cell activity in serum and urine of normal cats over a range of ages. Bone alkaline phosphatase (BAP), a marker of bone formation, was measured in serum using wheatgerm lectin precipitation (WGL) and by ELISA. The curve derived from serial dilution of feline serum was parallel with the ELISA standard curve, indicating species cross-reactivity, and there was a significant relationship between assays (rs = 0.97, P < 0.001). Deoxypyridinoline (DPD), a marker of bone resorption, was measured in its total form in urine by HPLC and ELISA, and in its free form in serum and urine by ELISA. The dilution curve for free DPD in urine showed parallelism with the assay standard curve; however, the curves for total DPD in urine and serum did not. A significant relationship was established between total urinary DPD (HPLC) with total serum DPD (rs = 0.69, P < 0.001), and with free urinary DPD (rs = 0.95, P < 0.001) concentrations. Carboxy-terminal telopeptide of type I collagen (CTX) concentration, another marker of bone resorption, was measured in serum and urine by ELISA, and there was a significant relationship between assays (rs = 0.82, P < 0.001). CTX could not be measured reliably using an auto-analysis method. A significant relationship was established between total urinary DPD (HPLC) with serum CTX (rs = 0.59, P < 0.05), and urinary CTX (rs = 0.65, P < 0.001) concentrations. BAP (ELISA and WGL), total urinary DPD (HPLC), urinary CTX (ELISA), and serum CTX (ELISA) concentrations were significantly inversely correlated with age (rs = -0.66, -0.88, -0.61, -0.70, and -0.51, P < 0.05 respectively). Cats under two years of age had significantly higher BAP, total urinary DPD (HPLC), and urinary CTX concentrations compared to older cats. In conclusion, this study has shown that a number of commercially available assays provide reliable methods for non-invasively monitoring bone cell activity in cats and has shown that bone turnover decreases within the first two years of life, until complete skeletal maturity is attained. Future studies can now be directed at evaluating the potential clinical application of these methods.