[Determination of beta-hexosaminidase and gamma-glutamyltranspeptidase activities in urine of pregnant women to monitor alcohol consumption]

BACKGROUND

Drinking of alcohol by pregnant women provokes many fetal development disorders, first of all the function of central nervous system and can lead to Fetal Alcohol Syndrome - FAS.

AIM

Aims of investigation were to determine beta - hexosaminidase (HEX) and gamma - glutamyltranspeptidase (GGT) activity in the urine to monitoring consumption of alcohol by pregnant women in first trimester and to assess the effect of ethyl alcohol on fetus development.

MATERIAL AND METHODS

22 pregnant women, who did not declare consumption of ethanol containing drinks. The level of creatinine, GGT and HEX in urine was analysed.

RESULTS

Preliminary results of our study indicate that determination of GGT and HEX activities could be useful in monitoring of alcohol consumption during pregnancy.

Enzymuria following amphotericin B application in the rat

The effect of amphotericin B application on urinary renal tubule enzyme excretion was investigated in rats treated with amphotericin B (1.5 mg kg-1 b.i.d., i.v.) for 4 days. Application of amphotericin B induced a significant higher daily urinary enzyme activity of the renal tubular enzymes N-acetyl-beta-glucosaminidase (NAG), beta-glucuronidase (GRS), alanine-aminopeptidase (AAP) and gamma-glutamyltransferase (GGT) in comparison with controls and sodium deoxycholate treated animals as well. A significant increase in the renal excretion of NAG, GRS, AAP and GGT occurred after the first day of amphotericin B treatment and continued until the fourth day. Following treatment for 4 days with amphotericin B urine AAP activity amounted to 69 +/- 19 U g-1 creatinine, control: 39 +/- 7 U g-1 creatinine (P < 0.05). After 4 days GGT excretion increased to 803 +/- 238 U g-1 creatinine, control: 445 +/- 106 U g-1 creatinine (P < 0.05). At the fourth day NAG excretion was 80 +/- 39 U g-1 creatinine, control: 23 +/- 5 U g-1 creatinine (P < 0.05) and GRS 724 +/- 604 U g-1 creatinine (amphotericin B), control: 276 +/- 158 U g-1 creatinine (P < 0.05). Treatment with amphotericin B decreased the creatinine clearance significantly: 0.94 +/- 0.16 ml-1 min-1 vs. control 1.35 +/- 0.29 ml-1min-1 (P < 0.05). Fractional sodium and potassium excretion was not influenced by amphotericin B. The application of sodium deoxycholate had no influence on urinary renal tubular enzyme activity. The results show that amphotericin B application induces early enzymuria of renal tubule enzymes suggesting damage of proximal renal tubules.

Narthecium ossifragum (L.) huds. causes kidney damage in goats: morphologic and functional effects

We studied the effects of Narthecium ossifragum on goat kidneys. Twenty-five Norwegian dairy goats, 5 weeks to 4 months of age, were orally dosed with an aqueous extract from N. ossifragum. In experiment 1, we studied microscopic and functional changes in 12 animals that were euthanatized 2, 3, 4, 5, and 6 days after treatment. In experiment 2, we included ultrastructural studies on serial renal biopsies and urine analysis from five extract-treated animals and two controls. In addition, urine samples were collected from four dosed and two control goats. Ultrasonography revealed perirenal and retroperitoneal fluids. Microscopic changes were observed after 6 hours. The findings, most obvious in the inner cortex and the outer medulla, consisted of cytoplasmic vacuolization, interstitial edema, and focal necrosis of tubular epithelial cells. Ultrastructurally, the tubules had loss of microvilli, irregular cytoplasmic vacuolization, mitochondrial swelling with loss of cristae, and irregular but continuous basement membranes even with necrosis. In the glomeruli, there were occasional endothelial damage and shortening and swelling of the foot processes. Peritubular capillaries had breaks in the vessel walls and irregular endothelial cell edema, and the interstitium had marked edema. The functional lesions included elevated serum urea, creatinine, and magnesium concentrations, a slight decrease in serum calcium concentration, elevated urine protein and urine protein-creatinine ratio, and increased activities of urine alkaline phosphatase and gamma glutamyl transferase. Our findings indicate a fast-acting toxic principle inducing damage by both direct toxic and secondary ischemic effects.

The influence of lipoic acid on adriamycin induced nephrotoxicity in rats

Adriamycin, which is widely used in the treatment of various neoplastic conditions, exerts toxic effects in several organs. Adriamycin nephrotoxicity has been recently documented in a variety of animal species. The present study was designed to investigate the effect of lipoic acid on the nephrotoxic potential of adriamycin. The study was carried out with adult male albino rats of Wistar strain. Test animals were divided into four groups of six rats each as follows: Group I (control) received only normal saline throughout the course of the experiment. Group II (ADR) received intravenous injections of adriamycin through the tail vein (1 mg kg(-1) body wt day(-1)) once a week for a period of 12 weeks. Group III (LA) received lipoic acid (35 mg kg(-1) body wt day(-1)) intraperitoneally once a week for a period of 12 weeks. Group IV (ADR + LA) received a single injection of lipoic acid intraperitoneally 24 h prior to the administration of adriamycin through the tail vein once a week for a period of 12 weeks. Intravenous injections of adriamycin resulted in decreased activities of the glycolytic enzymes; hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase in the rat renal tissue. The gluconeogenic enzymes, glucose-6-phosphatase and fructose-1,6-diphosphatase, showed a decline in their activities on adriamycin administration. The transmembrane enzymes namely the Na+,K+-ATPase, Ca2+-ATPase, Mg2+-ATPase and the brush-border enzyme alkaline phosphatase also showed a decrease in their activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush-border membrane damage. Decreased activities of the TCA cycle enzymes isocitrate dehydrogenase, succinate dehydrogenase and malate dehydrogenase, suggest a loss in mitochondrial function and integrity. Nephrotoxicity was evident from the increased excretions of N-acetyl-beta-D-glucosaminidase and gamma-glutamyl transferase in the urine of adriamycin administered rats. These biochemical disturbances were effectively counteracted on pre-treatment with lipoic acid, which brought about an increase in the activities of glycolytic enzymes, ATPases and the TCA cycle enzymes. On the other hand, the gluconeogenic enzymes showed a further decrease in their activities on lipoic acid pretreatment. LA pretreatment also restored the activities of the urinary enzymes to normal. These observations shed light on the nephroprotective action of lipoic acid rendered against experimental aminoglycoside toxicity.

Urinary actin, interleukin-6, and interleukin-8 may predict sustained ARF after ischemic injury in renal allografts

BACKGROUND

Cellular damage and inflammation after ischemia contribute to sustained acute renal failure (ARF).

METHODS

To quantify cellular damage and inflammation in postischemic ARF and identify markers of renal functional outcome, urine specimens from 40 renal allograft recipients, including 30 cadaveric (9 "sustained ARF" and 21 "recovery" subjects) and 10 living donor allografts ("LD"), were analyzed for actin, gamma-glutamyl transpeptidase (GGTP), lactate dehydrogenase (LDH), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) during the first posttransplant week.

RESULTS

On day 0, urinary actin, GGTP, IL-6, and IL-8 were elevated in recipients destined to have sustained ARF compared with those destined to recover. Median values per gram of urine creatinine in the sustained ARF, recovery, and LD groups were 263.9, 0.0, and 0.0 microg for actin; 5000.0, 892.9, and 5555.6 U for GGTP; 193.1, 27.2, and 10.5 ng for IL-6; and 382.0, 17.8, and 18.5 ng for IL-8, respectively. In contrast, urinary LDH and TNF-alpha increased in recipients with recovering function compared with those who had sustained ARF. The corresponding median values were 36.7 and 16.3 U (recovery versus sustained ARF) for LDH, and 18.4 and 7.6 ng (LD versus sustained ARF) for TNF-alpha. Computational analyses using the Receiver Operating Characteristic Curve found that elevated urinary actin, IL-6, and IL-8 on day 0 were strong predictors of sustained ARF, where the calculated areas under the curve were 0.75, 0.91, and 0.82, respectively.

CONCLUSION

Increased urinary actin, IL-6, and IL-8 may be useful markers for the prediction of sustained ARF after ischemia.

Activation of alpha(1)-adrenergic receptors potentiates the nephrotoxicity of ethylene dibromide

Ethylene dibromide (EDB) has been used as a model compound for eliciting hepato- and nephrotoxicity. Conjugation with glutathione (GSH) has been shown to play a role in the bioactivation of EDB. The aim of this study was to determine whether activation of alpha(1)-adrenergic receptors, which causes a decrease in cellular GSH levels, could modulate the nephrotoxicity of EDB. For this purpose, male ICR mice were treated with EDB and/or the alpha-adrenergic agonist, phenylephrine (Pe), or the alpha-adrenergic antagonist, phentolamine (Phe). Animals treated with EDB (40 mg/kg, i.p.) had a 9.3-fold increase in urinary gamma-glutamyltranspeptidase (GGTP: EC 2.3.2.2) activity and a 38% decrease in renal non-protein bound sulfhydryl (NPSH) levels; however, animals co-treated with EDB and Pe (50 mg/kg, i.p.) exhibited a 27.8-fold increase in urinary GGTP activity and a 60% decrease in NPSH levels. The enhanced presence of urinary GGTP and decrease in cellular levels of NPSH was nearly blocked by treating animals concomitantly with EDB and Phe (10 mg/kg, i.p.) or EDB, Pe, and Phe. Histopathological examination revealed the enhanced degree of tissue damage and necrosis following treatment with EDB and Pe, and the protective effect of Phe at ameliorating EDB toxicity. These results indicate that factors that can influence alpha-adrenergic receptors may be critical in assessing dose-response data used in the risk assessment process.

Protein-rich diet attenuates cyclosporin A-induced renal tubular damage in rats

OBJECTIVE

The objective of the present study was to look at the effect of a protein-rich diet on cyclosporine A (CsA)-induced acute nephrotoxicity in rodents using markers of tubular damage.

DESIGN

Female Sprague-Dawley rats were conditioned to either a standard or a casein-rich diet for 2 weeks. Then, they were given CsA intraperitoneally (25 mg/kg/24 h or an equivalent volume of vehicle (Cremophor EL; Sigma Chemical Co, St. Louis, MO) for 7 days at 7 AM.

RESULTS

During CsA treatment, bodyweight, caloric consumption, water intake, and urine output were not significantly different in animals fed with the standard Rat Chow and those on the high-protein feeding. On days 1 and 7, the 24-hour urine excretion of N-acetyl-beta-d-glucosaminidase (NAG) and beta-galactosidase (beta-GAL) were significantly (P < .001) lower in CsA-treated rats on the high-protein diet than in those on the standard Rat Chow. After 7 days of treatment with CsA, no significant difference in the renal function level was found between rats fed with the standard or the casein-rich diet. The post-necrotic cellular regeneration in renal cortex was significantly lower (p<0.001) in CsA-treated rats on the high-protein than on the standard diet. In CsA-treated rats on the standard diet, immunogold labeling showed a massive and specific concentration of the drug into lysosomes of proximal tubular cells. Contrastingly, no gold particle was found over the lysosomes of animals given the rich-protein feeding.

CONCLUSION

In our current experimental conditions, a protective effect of high-casein diet against CsA-induced proximal tubular damage was observed in Sprague-Dawley rats.

Measurement of tubular enzymuria facilitates early detection of acute renal impairment in the intensive care unit

BACKGROUND

Early detection of acute tubular necrosis (ATN) could permit implementation of salvage therapies and improve patient outcomes in acute renal failure (ARF). The utility of single and combined measurements of urinary tubular enzymes in predicting ARF in critically ill patients has not been evaluated using the receiver-operating characteristic (ROC) plot method.

METHODS

In this prospective pilot study, 26 consecutive critically ill adult patients admitted to the intensive-care unit were studied. Urine samples were collected twice daily for up to 7 days. ARF was defined as an increase in plasma creatinine of > or = 50% and > or = 0.15 mmol/l. ROC plot analysis was applied to the tubular marker data to derive optimum cut-offs for ARF.

RESULTS

Four of the 26 study subjects (15.4%) developed ARF. Indexed to urinary creatinine concentration, gamma glutamyl transpeptidase (gamma GT), alkaline phosphatase (AP), N-acetyl-glucosaminidase (NAG), and alpha- and pi-glutathione S-transferase (alpha- and pi-GST) but not lactate dehydrogenase (LDH) were higher in the ARF group on admission (P<0.05). gamma GT, and alpha- and pi-GST remained elevated at 24 h. The onset of ARF based on changes in plasma creatinine varied from 12 h to 4 days (median 36 h). ROC plot analysis showed that gamma GT, pi-GST, alpha-GST, AP and NAG had excellent discriminating power for ARF (AUC 0.950, 0.929, 0.893, 0.863 and 0.845, respectively). The discriminating strength of creatinine clearance, while lower, was still significant (AUC 0.796). Positive and negative predictive values for ARF on admission were 67/100% for gamma GT, 67/90% for AP, 60/95% for alpha-GST, and 67/100% for pi-GST indices. Positive and negative predictive values for ARF for creatinine clearance < or = 23 ml/min were 50 and 91%, respectively. Creatinine clearances tended to be lower in ARF than in non-ARF patients on admission (P=0.06) and were significantly lower (P=0.008) after 12 h. Plasma urea and fractional sodium excretion were unhelpful.

CONCLUSIONS

Tubular enzymuria on admission to the ICU is useful in predicting ARF. The cheapness and wide availability of automated assays for gamma GT and AP suggests that estimation of these enzymes in random urine samples may be particularly useful for identifying patients at high risk of ARF.

[Urinary enzyme excretion in childhood uropathy]

INTRODUCTION

Renal tissue, and tubules are rich in enzymes but enzyme measurement in the urine as diagnostic parameters in renal diseases have not yet been generally accepted as routine procedures.

AIMS

To study urinary enzyme excretion in childhood obstructive uropathy and compares the diagnostic efficiency of them.

METHODS

Excretion of the enzymes alkaline phosphatase (ALP), gamma-glutamyltransferase (gamma-GT), N-acetyl-beta-D-glucosaminidase (NAG) and leucine aminopeptidase (LAP) has been investigated in urine of 34 children suffering from obstructive uropathy and in 31 healthy controls by photometric kinetic analysis using synthetic substrates.

RESULTS

Urinary excretion of both enzymes significantly increase--2-10 times higher than normal controls--indicates tubular damage. In this study the following relations were found in specificity and in sensitivity: ALP < LAP < gamma-GT < NAG.

CONCLUSIONS

Elevated urinary enzyme excretion may be helpful in identifying upper tract obstruction, which if left untreated may cause progressive renal deterioration. It has a role in helping to determine the surgical correction or can be safely followed without fear of parenchymal damage.

Mercury in dental restoration: is there a risk of nephrotoxicity?

BACKGROUND

Concern has been voiced about exposure to mercury (Hg) from dental amalgam fillings, and there is a need to assess whether this leads to signs of nephrotoxicity.

METHODS

A total of 101 healthy adults (80 males and 21 females) were included in this study. The population as grouped into those having amalgam fillings (39 males and 10 females) and those without (41 males and 11 females). Hg was determined in blood, urine, hair and nails to assess exposure. Urinary excretion of beta2-microglobulin (beta2M), N-acetyl-beta-D-glucosaminidase (NAG), gamma-glutamyltransferase (gammaGT) and alkaline phosphatase (ALP) were determined as markers of tubular damage. Albuminuria was assayed as an early indicator of glomerular dysfunction. Serum creatinine, beta2M and blood urea nitrogen (BUN) were determined to assess glomerular filtration.

RESULTS

Hg levels in blood and urine were significantly higher in persons with dental amalgam than those without; in the dental amalgam group, blood and urine levels of Hg significantly correlated with the number of amalgams. Urinary excretion of NAG, gammaGT and albumin was significantly higher in persons with dental amalgam than those without. In the amalgam group, urinary excretion of NAG and albumin significantly correlated with the number of fillings. Albuminuria significantly correlated with blood and urine Hg.

CONCLUSION

From the nephrotoxicity point of view, dental amalgam is an unsuitable filling material, as it may give rise to Hg toxicity. Hg levels in blood and urine are good markers of such toxicity. In these exposure conditions, renal damage is possible and may be assessed by urinary excretions of albumin, NAG, and gamma-GT.

The activity of beta-hexosaminidase (uHex) and gamma-glutamyltransferase (uGGT) in urine as non-invasive markers of chronic alcohol abuse: II. Opiate-dependent subjects receiving methadone substitution

The usefulness of beta-hexosaminidase (uHex) and gamma-glutamyltransferase (uGGT) activity in urine as markers of chronic alcohol abuse was examined in male methadone programme participants. The group consisted of 24 non-abusing and 21 alcohol-abusing men. It has been demonstrated that the uHex test is one of the best alcohol abuse markers for opiate-dependent individuals (Receiver Operating Characteristic (ROC) area under the curve (AUC) 0.82, sensitivity 0.70, specificity 0.82). The uGGT test can be used as a marker of alcohol abuse in opiate-dependent men, however, its parameters are worse than those of uHex (ROC AUC 0.73, sensitivity 0.71, specificity 0.77). Among serum markers, only the relative amount of carbohydrate-deficient transferrin (s%CDT) has parameters sufficient for diagnostic use (ROC AUC 0.74, sensitivity 0.60, specificity 0.86). Factors other than alcohol can render the commonly used sGGT and sHex tests useless (differences between means for abusing and abstinent patients were insignificant, AUC ROC were lower than 0.7-0.65 and 0.69, respectively). Their good parameters, low costs, ease of use and non-invasive character are all features which make uHex and uGGT highly useful tools in the detection of chronic alcohol abuse in opiate-dependent patients participating in a methadone substitution programme.

The activity of beta-hexosaminidase (uHex) and gamma-glutamyl-transferase (uGGT) in urine as non-invasive markers of chronic alcohol abuse: I. Alcohol-dependent subjects

It has been demonstrated that in alcohol-dependent men the uHex test is one of the most powerful discriminating tools, while uGGT has a discriminating power similar to that of sHex but worse than that of uHex, sGGT and s%CDT. Receiver Operating Characteristic (ROC) areas under the curves (AUC) for uHex, uGGT, s%CDT, sHex and sGGT were 0.92, 0.79, 0.88, 0.79 and 0.92, respectively. Due to their good parameters, low cost, ease of use and non-invasive character the uHex and uGGT tests are useful tools for the detection of chronic alcohol abuse.

Calculation of urinary enzyme excretion, with renal structure and function in dogs with pyometra

The urinary enzyme markers of renal damage, alkaline phosphatase (AP), gamma-glutamyl transferase (GGT) and N-acetyl-beta-glucosaminidase (NAG), glomerular filtration rate (GFR) and renal biopsies were studied to evaluate renal status in dogs with pyometra. After ovariohysterectomy, urinary enzymes were measured daily for 12 days in 55 dogs, and again at a later follow-up visit. Thirteen dogs had high levels of at least one enzyme at initial presentation. Seventeen dogs had a transient increase in urinary enzyme values between one and five days after surgery. Enzyme values usually declined to low activities within 12 post-operative days. Renal biopsies demonstrated tubular abnormalities in many dogs. Mean GFR was 2.4 and 2.0 ml min(-1) kg(-1), respectively on day 1 post-operatively and at the follow-up visit 1-4 months later. High urinary enzyme values often reflected extensive lesions in renal proximal tubular cells and sometimes reduced GFR.

Effects of renal sorbitol accumulation on urinary excretion of enzymes in hyperglycaemic rats

We studied the effects of epalrestat, a specific inhibitor of aldose reductase, on renal sorbitol accumulation and the resulting urinary enzyme excretion in hyperglycaemic rats. The activities of proximal tubule-derived enzymes such as N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), gamma-glutamyltranspeptidase (GGT) and dipeptidyl aminopeptidase IV (DAPIV) in urine were determined in five groups of male Wistar rats (each n = 7): (a) 0.9% saline-loaded, (b) 10% glucose-loaded, (c) 10% glucose-loaded with epalrestat pretreatment, (d) 10% mannitol-loaded and (e) 10% mannitol-loaded with epalrestat pretreatment. Epalrestat was given mixed in chow at a dose of 50 mg/kg body weight. Urinary NAG, AAP, GGT and DAPIV activities were significantly increased (P<0.005, P<0.05, P<0.01, P<0.01, respectively) by the induction of hyperglycaemia. In contrast, enzyme excretion was not increased in the mannitol- or saline-loaded groups. Pre-treatment with epalrestat completely prevented the increased urinary excretion of NAG, AAP and GGT. At the end of the infusion study, renal cortical glucose concentrations of the glucose-loaded groups with and without epalrestat pretreatment were approximately fivefold higher than those of the mannitol- or saline-loaded groups (P<0.005 each). Renal cortical sorbitol concentrations of the glucose-loaded group was also approximately twofold higher than those of the mannitol- or saline-loaded groups (P<0.01 each). However, in the group that received both glucose and epalrestat, renal cortical sorbitol concentration was not increased. These results suggest that accumulation of intracellular sorbitol leads to proximal tubular cell dysfunction and abnormal enzymuria.

Renal involvement in dogs with babesiosis

Proteinuria, and renal tubular casts and epithelial cells in urine sediment, are commonly observed in both complicated and uncomplicated babesiosis, but do not necessarily reflect or predict renal failure. This study investigated the presence and degree of renal damage in canine babesiosis. Renal function and integrity were evaluated using serum urea and creatinine, serum electrolytes (sodium and potassium), fractional clearance of sodium (FcNa) and potassium (FcK), urine enzyme activity of gamma-glutamyl transpeptidase and alkaline phosphatase, urine protein:creatinine ratio, and urinalysis. One control group (n = 10) and 3 groups of babesiosis cases were studied: mild uncomplicated (n = 10), severe uncomplicated (n = 11), and complicated (n = 9). All babesiosis groups showed well-concentrated urine. Mean serum urea was elevated in the severe and complicated groups, and was significantly different from the control group. There was no statistically significant difference between the groups for creatinine, although the complicated group had a mean value above the normal reference range. Hypokalaemia was uncommon in all the groups. Hyperkalaemia was present in only 2 dogs in the complicated group. Marginal hyponatraemia was present in a minority of dogs in all groups. The serum electrolytes were not significantly different between groups. There was no overall elevation, nor any statistically significant difference in both the FcNa and FcK between the groups. Only 1 dog, in the complicated group, showed marked enzymuria. Proteinuria was a common finding and was significantly different between the severe and complicated groups and the control group. Some dogs in all groups had renal tubular epithelial cells in the urinary sediment, which increased in severity from the mild to the complicated groups and was significantly different from the control group. This study demonstrated that minimal renal damage occurs more often in canine babesiosis than significant damage or acute renal failure.

Effect of administration of nonsteroidal anti-inflammatory drugs before surgery on renal function in clinically normal dogs

OBJECTIVES

To investigate renal function in clinically normal dogs undergoing general anesthesia for ovariohysterectomies that received nonsteriodal antiinflammatory drugs (NSAID) before surgery.

ANIMALS

40 clinically normal dogs.

PROCEDURE

After induction of anesthesia, dogs were given an analgesic. Renal function was assessed before surgery and 24 and 48 hours after surgery by means of serum urea and creatinine concentrations, fractional clearance of sodium (FC(Na)), urine gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) activities, and urine analysis. Ten dogs in each of 4 groups received ketorolac tromethamine (0.5 mg/kg of body weight), ketoprofen (1 mg/kg), carprofen (4 mg/kg), or morphine (0.1 mg/kg; control group).

RESULTS

Duration of general anesthesia ranged from 1.75 to 5 hours, with a mean of 3 hours. Two ketorolac- and 2 ketoprofen-treated dogs had transient azotemia. A significant decrease in the FC(Na) between before surgery and 24 hours after surgery, and between before surgery and 48 hours after surgery, was found in ketoprofen- and carprofen-treated dogs. Ketorolac-, ketoprofen-, and morphine-treated dogs had a decrease in urine specific gravity. Two ketorolac, 1 ketoprofen-, 1 carprofen-, and 4 morphine-treated dogs had increases in renal tubular epithelial cells on urine sediment examination 24 hours after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

In clinically normal dogs undergoing general anesthesia and elective surgery, the use of NSAID as analgesics is not contraindicated. Compared with ketorolac or ketoprofen, carprofen had the least effect on renal function and integrity.

Renoprotective role of nifedipine during gentamicin therapy: randomized controlled trial

AIM

To investigate the protective effect of nifedipine, a dihydropyridine calcium-channel blocker, on renal function (glomerular and tubular) in patients treated with gentamicin, an aminoglycoside antibiotic.

METHODS

Thirty-two patients with gentamicin sensitive upper urinary tract infection have been screened and randomized to two groups. The placebo group was given gentamicin and placebo, and the intervention group gentamicin and nifedipine. Gentamicin was given in slow intravenous injection every 12 hours for 10 days, and nifedipine 10 mg orally, 3 times a day.

RESULTS

Nifedipine administration during gentamicin therapy promoted primarily the glomerular filtration. In 62% of the patients treated with nifedipine creatinine clearance increased significantly by the end of the study. In the placebo group, 69% of the patients had a creatinine clearance significantly below the baseline at the end of the study. The decrease in creatinine clearance by more than 50% from the initial values was found in 2 patients (1 in each group). There was a significant increase in gammaGT/creatinine clearance ratio in both groups at the end of therapy, indicating that nifedipine did not prevent the brush-border membranous enzyme release caused by gentamicin.

CONCLUSION

Nifedipine has positive effects on renal hemodynamics in patients treated with gentamicin. Most likely, the mechanism of action is an increase in glomerular filtration caused by preglomerular vasodilatation.

Renal effects of carprofen administered to healthy dogs anesthetized with propofol and isoflurane

OBJECTIVE

To evaluate renal effects of carprofen in healthy dogs following general anesthesia.

DESIGN

Randomized clinical trial.

ANIMALS

10 English hound dogs (6 females and 4 males).

PROCEDURE

Dogs were randomly assigned to control (n = 5) or carprofen (5) groups. Anesthesia was induced with propofol (6 to 8 mg/kg [2.7 to 3.6 mg/lb] of body weight, i.v.) and maintained with isoflurane (end-tidal concentration, 2.0%). Each dog underwent two 60-minute anesthetic episodes with 1 week between episodes, and mean arterial blood pressure was maintained between 60 and 90 mm Hg during each episode. Dogs in the carprofen group received carprofen (2.2 mg/kg [1 mg/lb], p.o.) at 9:00 AM and 6:00 PM the day before and at 7:00 AM the day of the second anesthetic episode. Glomerular filtration rates (GFR) were determined during each anesthetic episode by use of renal scintigraphy. Serum creatinine and BUN concentrations and the urine gamma-glutamyltransferase-to-creatinine concentration (urine GGT:creatinine) ratio were determined daily for 2 days before and 5 days after general anesthesia.

RESULTS

Significant differences were not detected in BUN and serum creatinine concentrations, urine GGT:creatinine ratio, and GFR either between or within treatment groups over time.

CONCLUSIONS AND CLINICAL RELEVANCE

Carprofen did not significantly alter renal function in healthy dogs anesthetized with propofol and isoflurane. These results suggest that carprofen may be safe to use for preemptive perioperative analgesia, provided that normal cardiorespiratory function is maintained.

Protective effect of oral L-arginine administration on gentamicin-induced renal failure in rats

We investigated the effects of orally supplemented L-arginine, the substrate of nitric oxide (NO) and N(omega)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide-synthase inhibitor in gentamicin-induced renal failure. Rats were given gentamicin (100 mg/kg/day s.c.), gentamicin and L-arginine (2 g/l, drinking water), gentamicin and L-NAME (100 mg/l, drinking water) or gentamicin plus L-arginine and L-NAME. After 8 days, the gentamicin group developed marked renal failure, characterized by a significantly decreased creatinine clearance and increased blood creatinine, fractional excretion of sodium, fractional excretion of lithium, urine gamma glutamyl transferase, systolic blood pressure and daily urine volume when compared to controls. Renal histological analysis confirmed tubular necrosis. L-arginine administration caused normalization of these parameters, whereas L-NAME led to aggravation of the failure. Concomitant administration of L-NAME and L-arginine to gentamicin-treated rats caused no significant changes when compared to the rats receiving gentamicin alone. We conclude that L-arginine supplementation has beneficial effects in gentamicin-induced renal failure in rats and that these effects are reversed by the NO-synthase inhibitor, L-NAME.

Effects of general anesthesia and surgery on renal function in healthy dogs

OBJECTIVES

To evaluate renal function in healthy dogs undergoing general anesthesia and ovariohysterectomy without concurrent IV administration of fluids.

ANIMALS

35 healthy client-owned dogs.

PROCEDURE

Dogs were medicated with promazine hydrochloride (0.05 mg/kg of body weight, SC) approximately 45 minutes before induction of anesthesia with thiopental sodium (10 to 15 mg/kg, IV). Anesthesia was maintained with 2% halothane in oxygen. Ovariohysterectomies were performed by senior veterinary students under the direct supervision of a veterinary surgeon. Renal function was assessed (serum urea and creatinine concentrations, fractional clearance of sodium, urine alkaline phosphatase [ALP] and gamma-glutamyltransferase [GGT] activities, urine specific gravity, and enumeration of renal tubular epithelial cells in urine sediment) prior to and 24 and 48 hours after surgery.

RESULTS

Duration of general anesthesia ranged from 80 to 310 minutes. Urine specific gravity and ALP activity and serum urea and creatinine concentrations did not change over time. Fractional clearance of sodium decreased 24 and 48 hours after surgery, whereas urine GGT activity and the ratio of urine GGT activity to urine creatinine concentration increased 24 hours after surgery, compared with presurgery values. Renal tubular epithelial cells increased in number in urine sediment from 11 of 35 (31.4%) dogs and 5 of 35 (14.3%) dogs 24 and 48 hours after surgery, respectively. However, this increase was not clinically relevant.

CONCLUSIONS AND CLINICAL RELEVANCE

Intravenous administration of fluids to healthy dogs undergoing general anesthesia and elective surgery may not be necessary for maintenance of renal homeostasis.

The susceptibility to nephrotoxicity of streptozotocin-induced diabetic rats subchronically exposed to cadmium chloride in drinking water

Streptozotocin-induced diabetic rats and normal non-diabetic (ND) rats were exposed to cadmium chloride in drinking water in doses of 0, 50 and 100 ppm for 90 days. There was a dose-related increase in urinary protein and enzymes in the diabetic group, but an increase in proteinuria only in the high exposure subgroup of the ND group. It is suggested that diabetic rats induced by streptozotocin are more susceptible to cadmium nephrotoxicity than normal (ND) rats. Metallothionein synthesis in liver was estimated to be similar in both the diabetic and non-diabetic groups after exposure to cadmium. Less excretion of cadmium in urine and greater accumulation of cadmium in kidney were observed in the diabetic group, and this may be one of the mechanisms underlying the susceptibility of diabetic animals to the effects of cadmium. Further biochemical and histological studies are required in order to explain the detailed events involved in inducing such changes in the toxicokinetics of cadmium.

Time course of chronic oral cadmium nephrotoxicity in Wistar rats: excretion of urinary enzymes

Twelve male and female Wistar rats each received cadmium (as CdCl2) in their diet at concentrations of 0, 10, 50, and 250 ppm for 72 weeks. After 1, 4, 8, 13, 18, 26, 32, 45, 57, and 68 weeks a total of 8 enzymes from different cellular compartments of the nephron were measured. At the end of the study period, the kidneys were examined histopathologically. Concentrations up to and including 50 ppm did not induce any adverse effect. At 250 ppm, growth of male and female animals was markedly retarded. Significantly increased activities of the cytosolic phosphohexose isomerase were excreted by males and females receiving 250 ppm at all timepoints from week 13. The values of the mitochondrial glutamate dehydrogenase were mostly elevated from week 1 to 57, however, due to a wide scatter range, were only occasionally significantly different from control values. The brush border enzymes (gamma-glutamyl transferase, alkaline phosphatase and leucine arylamidase) were not changed in a relevant manner in female rats, while in 250 ppm males the excreted activity of ALP and LAP from week 1 to week 18, and that of GGT during the entire study period were significantly lower than the control values. Excretion of the lysosomal enzymes aryl sulfatase A, beta-galactosidase, and beta-N-acetyl-D-glucosaminidase was at no time influenced in a noteworthy manner. Histopathology after 72 weeks revealed chronic but also acute degenerative changes in the kidneys of 250 ppm males and females. A comparison of published data on persons having undergone high cadmium exposure with the results presented here shows remarkable differences.

Pharmacokinetics of ibuprofen after intravenous and oral administration and assessment of safety of administration to healthy foals

OBJECTIVE

To determine pharmacokinetics of ibuprofen in healthy foals and to determine clinical effects after oral administration for 6 days.

ANIMALS

7 healthy 5- to 10-week-old foals.

PROCEDURE

Serum concentrations of ibuprofen were measured after IV and oral (nasogastric tube) administration at dosages of 10 and 25 mg/kg of body weight. Foals were given ibuprofen (25 mg/kg, PO, q 8 h) as a paste for 6 days. Serum and urine were obtained before and after the 6-day period.

RESULTS

Half-life of elimination (Kel t1/2) of IV-administered ibuprofen (ie, 10 and 25 mg/kg), was 79 and 108 minutes, maximal serum concentration (C(MAX)) was 82 and 160 microg/ml, and clearance was 0.003 and 0.002 L/kg/min, respectively. At the higher dosage, clearance was significantly lower and C(MAX) was significantly higher. Ibuprofen given via nasogastric tube resulted in Kel t1/2 of 81 and 100 minutes and C(MAX) of 22 and 52 microg/ml for 10 and 25 mg/kg, respectively. The absorption half-life was 13 minutes, and bioavailability ranged from 71 to 100%. Foals remained healthy during oral administration of ibuprofen. Serum urea nitrogen, creatinine, and L-iditol dehydrogenase values increased significantly, and gamma-glutamyltransferase (GGT) activity and osmolality decreased, but all measurements remained within reference ranges. Urine GGT activity doubled. Necropsy did not reveal gross or histologic renal lesions attributable to ibuprofen. Acute gastric ulcers were evident in 1 foal, although clinical signs of ulcers were not observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Ibuprofen can be given safely to healthy foals at dosages < or = 25 mg/kg every 8 hours for up to 6 days.