[Habekacin: a new aminoglycoside. Study of nephrotoxicity in rats in comparison with gentamicin, netilmicin and amikacin]. / L'habékacine: un nouvel aminoglycoside. Etude de la néphrotoxicité chez le rat en comparaison avec la gentamicine, la netilmicine et l'amikacine.

Habekacin is a new aminoglycoside antibiotic. In this study we want to know the effect of increasing dose of habekacin on renal function and on renal morphology. We decide to compare the renal alterations induced by habekacin to these provoked by gentamicin, netilmicin and amikacin. Female Wistar rats received intraperitonally a single injection daily of 10, 30, 50, 150 mg/kg of habekacin for seven days. Wistar rats received also 50 mg/kg gentamicin, 50 mg/kg netilmicin and 150 mg/kg amikacin. No mortality was observed in groups treated with 10, 30, 50 mg/kg habekacin but 50 per cent of rats died with 150 mg/kg habekacin. Habekacin--30 mg/kg seven days--induced a decrease of cortical enzymatic activities, an increase of the number of lysosomes, a great accumulation of myeloid bodies, an alteration of lysosomal membranes Habekacin--50 mg/kg seven days and 150 mg/kg--induced a decrease of creatinine clearance and ultrastructural alterations of renal tubular cells. Comparative studies with other aminoglycosides showed that amikacin--150 mg/kg was the lesser nephrotoxic drug. With a same dose of 50 mg/kg, gentamicin appeared lesser nephrotoxic than habekacin and habekacin seemed to induce a same degree of renal modifications than netilmicin. With the dose of 150 mg/kg habekacin this drug was higher nephrotoxic than 50 mg/kg gentamicin. In conclusion, if it could be necessary to use habekacin and to prefer this aminoglycoside to gentamicin from an antibacterial activity point of view it is necessary to keep in mind that this drug is potentially nephrotoxic and that the dosage had to be strictly respected.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of muzolimine, a new diuretic, on experimental gentamicin nephrotoxicity.

The administration of diuretic drugs increases the nephrotoxicity of aminoglycosides. Muzolimine is a new diuretic which acts on the ascending limb of the loop of Henle and on the distal tubule. It differs from frusemide in its strong lipid binding and in its action at the antiluminal cellular pole. We attempted to determine whether muzolimine increases the nephrotoxicity of gentamicin. Four groups of Wistar rats were studied: one control group, one group treated with muzolimine (15 mg/kg), one group treated with gentamicin (20 mg/kg), and one group treated with gentamicin and muzolimine. Muzolimine induced a moderate but significant decrease in creatinine clearance, increased urinary excretion of n-acetyl-beta-D-glucosaminidase, and a slight decrease in lysosomal latency. The action of muzolimine did not reduce enzyme activities of the renal cortex (AAP, NAG, sphingomyelinase). Gentamicin induced functional renal modifications known to characterise nephrotoxicity of aminoglycosides. The association of muzolimine and gentamicin did not provoke a greater decrease of creatinine clearance or a greater decrease in enzyme activities of the renal cortex. In conclusion, muzolimine does not seem to potentiate the nephrotoxic action of gentamicin. However, we note that the association of muzolimine and gentamicin provoked a greater decrease in mitochondrial oxygen consumption than that provoked by gentamicin alone. It also induced more marked reduction of the activity of renal sphingomyelinase. This point is important when it is considered that the appearance of myelin bodies in the renal cortex is secondary to the decrease of this enzyme.

Aminoglycoside-induced alterations of phosphoinositide metabolism.

There exists a strong interaction between aminoglycosides and phosphoinositides, and these membrane lipids are even considered as the drug receptors. To shed some light on the role of such an interaction in the drug nephrotoxicity, we have investigated the influence of aminoglycosides on phosphoinositide metabolism in kidney proximal tubules where these compounds accumulate. Experiments were carried out by measuring 32P labelling of phosphatidylinositol 4-phosphate (PI-P) and of phosphatidylinositol 4,5-bisphosphate (PI-P2) after incubation of homogenates of isolated proximal tubules with [gamma-32P] ATP. The treatment of rabbits with neomycin, gentamicin and amikacin (50, 50 and 300 mg/kg/day, respectively for seven days) promoted a decrease in 32P-PI-P2 and an increase in 32P-PI-P, when compared to the respective values observed in tubules from untreated rabbits. Under these conditions, the extent of modifications in lipid labelling was similar with the three drugs tested. In in vitro experiments, the exogenous addition of the above aminoglycosides to the incubation medium containing tubule homogenates from untreated rabbits also produced, in a dose dependent manner, a decrease in 32P-PI-P2 and an increase in 32P-PI-P. In the in vitro experiments, however, amikacin and gentamicin appeared to be less potent than neomycin. The results indicated moreover that phosphoinositide metabolism was more sensitive to the in vivo (vs. in vitro) action of the drugs. Phosphoinositides are involved in Ca2+ transport and/or mobilization processes, and aminoglycosides are known to interfere with the Ca2+ binding to membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Regenerating tubular cell process in rat kidney: influence of gentamicin treatment.

Aminoglycoside antibiotics are accumulated in lysosomes of proximal tubule cells in the renal cortex. After gentamicin administration in Wistar rats at the daily doses of 10 or 50 mg/kg during 4, 7 or 14 days, we have observed an increase of the number density of lysosomes from proximal cells, an increase of the mean lysosomal perimeter, and a rise of the lysosomal overloading with myeloid bodies. Analysis of lysosomal size distribution (as perimeters) during these treatments shows two kinds of lysosomes, small and large, the latter being characteristic of necrotized cells. A theoretical calculation between control lysosomal distribution of perimeters and the distribution of lysosome perimeters observed after treatment reveals an excess of the small type of lysosome during regenerative time (i.e. 8 days after the end of a 7-day treatment with 10 or 50 mg/kg of gentamicin). This calculation shows a regenerative process during the treatment with the high dose. This morphometric study of the proximal tubule cell during gentamicin treatment reveals the early events of cell damage before any biochemical changes in kidney cortex or blood creatinine level can be observed.

[Urinary excretion of phospholipids: index of aminoglycoside nephrotoxicity]. / Excrétion urinaire des phospholipides: indice de néphrotoxicité des aminoglycosides.

Aminoglycosides have a low molecular weight and bind weakly to proteins. They are easily filtered through the glomeruli, bind to phospholipid receptors located on the brush border of proximal tubule cells, and penetrate within the cells by endocytosis. Aminoglycosides decrease lysosomal A and C phospholipase and sphingomyelinase activities. This impairs the degradation of phospholipids, with formation of abnormal intralysosomal structures called myeloid bodies as a result. These myeloid bodies are gradually eliminated from the cells into the lumen of the tubule and excreted in the urine. We studied the urinary excretion of phospholipids following 1, 3, 5 and 10 days of treatment with gentamicin (3 mg/kg/day) or tobramycin (3 mg/kg/day) in patients with acute pyelonephritis. Infection-free, non-treated subjects were used as controls. Patients with a urinary tract infection treated by a quinolone made up a third group. Urinary N-acetyl-beta-D-glucosaminidase (NAG), an indicator of epithelial necrosis, was also evaluated. Results were expressed per ml urine, per mg creatinine and per 24 hours. Only the results expressed per mg creatinine appeared valid. No significant increase in serum creatinine or urinary NAG was found in patients under gentamicin. In the patients with a urinary tract infection not treated with an aminoglycoside, urinary phospholipid excretion on D1 was decreased as compared to controls (p less than 0.01). Urinary phospholipid excretion was never found to be increased in patients under aminoglycosides. No significant difference was found between males and females. Mistaken interpretations occurred if urinary excretion of phospholipids or NAG was not expressed per mg creatinine.(ABSTRACT TRUNCATED AT 250 WORDS)

[Can gentamicin nephrotoxicity in rats be modified by chronic administration of muzolimine?]. / La néphrotoxicité de la gentamicine peut-elle être modifiée chez le rat par l'administration chronique de muzolimine?

Some loop diuretics seem to increase gentamicin nephrotoxicity. We investigated this property for a new diuretic, muzolimine, in female Wistar rats. Each rat was given gentamicin intraperitoneally in a dosage that induces morphological and functional modifications in the kidneys (20 mg/kg/day for 7 days). Muzolimine was given in a daily dosage of 15 mg/kg starting 15 days before the first gentamicin injection and continuing throughout the seven-day gentamicin course. As compared to controls given gentamicin alone, modifications induced by the muzolimine-gentamicin combination showed no significant differences for the following criteria: renal accumulation of gentamicin, membrane lysosomal latency, renal oxidative mitochondrial metabolism and cortical activity of renal cathepsin B, N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase. However, slightly lower sphingomyelinase activities (p less than 0.05) were found for muzolimine + gentamicin as compared to gentamicin alone. Urinary NAG excretion increase more with muzolimine + gentamicin than with gentamicin alone, perhaps as a result of the very significant increase in urinary output observed with the diuretic. Our results show that, in contrast to findings with another loop diuretic, furosemide, the renal toxicity of gentamicin is not noticeably modified by concomitant administration of muzolimine.

[Effects of aminoglycosides on phosphoinositide metabolism in renal proximal tubules. In vivo and in vitro studies]. / Influence des aminoglycosides sur le métabolisme des phospho-inositides dans les tubules rénaux proximaux. Etudes in vivo et in vtiro.

Phosphoinositides play a major role in the interaction between aminoglycosides and renal epithelial cells. We therefore investigated both in vivo and in vitro, in isolated proximal tubules and in various parts of the rabbit kidney, the influence of neomycin, gentamicin and amikacin on the phosphoinositide metabolism. This was carried out by measuring the 32p incorporation into phosphatidylinositol 4,5-bisphosphates (PI-P2) and phosphatidylinositol 4-phosphates (PI-P). In aminoglycoside-treated animals, compared to untreated controls, the 32 p-PI-P2 and 32p-PI-P levels were decreased and increased respectively in proximal tubules and in cortical areas but these levels were unchanged in papilla and in medulla. Similar variations could be obtained after exogenous addition of aminoglycosides. PI-P2 is a key membrane component in the regulation of both the Ca2+ transport and the intracellular Ca2+ mobilization. Thus, the aminoglycoside-induced modifications of the phosphoinositide metabolism may be considered as a primary event in the drug toxicity which may result from alterations in the cell calcium homeostasis.

[Can fosfomycin reduce the nephrotoxicity of aminoglycosides?]. / La fosfomycine peut-elle réduire la néphrotoxicité des aminoglycosides?

Fosfomycin is an active antibiotic on Gram positive and Gram negative bacteria with a low toxicity in animals. To treat severe infections, it is recommended to associate fosfomycin with gentamicin. Wistar rats were given one of the following regimens for eight days : 100, 500 or 1 000 mg/kg fosfomycin, 50 mg/kg gentamicin or dibekacin, association of 100, 500, or 1 000 mg/kg fosfomycin and 50 mg/kg gentamicin or dibekacin. Control rats were given a saline solution. No renal histological alterations were identified with fosfomycin 100 mg/kg. Tubular dilatation and brush border rarefaction were observed with fosfomycin 500 and 1 000 mg/kg. These abnormalities did not seem related to fosfomycin itself but rather to the sodium load induced by fosfomycin treatment. A decrease in alanine aminopeptidase activity was noted for all doses of fosfomycin. Renal concentrations of gentamicin and dibekacin were not decreased by concomitant administration of fosfomycin. Fosfomycin, 100 mg/kg, did not change the nephrotoxic potential of gentamicin or dibekacin. Fosfomycin, 500 mg/kg, protected the kidney from the action of gentamicin or dibekacin. This effect seemed to be more pronounced for dibekacin than for gentamicin. Fosfomycin, 1 000 mg/kg, did not induce a more protective effect against the nephrotoxicity of these two aminoglycosides. Thus, we observed that fosfomycin combined with gentamicin or dibekacin reduced the degree of proximal tubular cell alterations, induced less modifications in alanine aminopeptidase, less lysosomal alterations, and a minor modification in sphingomyelinase activity.

[Acute experimental pyelonephritis. Treatment with tobramycin. Influence of the rhythm of administration on efficacy and renal tolerability]. / Pyélonéphrite aiguë expérimentale. Traitement par tobramycine. Influence du rythme d'administration sur l'efficacité et la tolérance rénale.

Acute experimental pyelonephritis was produced in rabbits by injecting E. coli (tobramycin MIC 1 mg/l) into the left kidney and temporarily obstructing the ureter. Animals were given 10 mg/kg tobramycin intramuscularly 48 h after surgery and subsequently every day for 7, 10 or 15 days, either in a single daily dose or in three divided doses at 8 h intervals. Animals were killed 24 h after the last injection. Comparison of results shows that kidneys were sterilized by a single daily dose but not by three divided daily doses. In rabbits given the single daily dose regimen, kidneys recovered a normal macroscopical and histological aspect, serum anti-E. coli antibodies rose more slowly and less significantly, serum creatinine increased less, and renal enzymatic activities were restored (alanine aminopeptidase and N-acetyl-beta-D-glucosaminidase). These findings suggest better efficacy and renal tolerance of the single daily dose regimen as compared to the three daily divided dose regimen in the treatment of acute experimental pyelonephritis.

Antibiotic nephrotoxicity.

Antibiotics are the principal cause of drug-associated nephropathy. They are responsible for acute interstitial nephropathy (AIN) or acute tubulo-interstitial nephropathy (ATIN) due to two different pathophysiologic mechanisms: a drug-induced immunologic process and direct action due to drug accumulation. 1) Ain of immunologic origin. These are rare and are induced either by beta-lactamines or by rifampicin. Among the beta-lactamines, methicillin is the most often responsible, while penicillin and ampicillin are less often, and only rarely are carbenicillin, oxacillin, nafcillin, cephalothin and cephalexin. Macroscopic hematuria occurring 10 to 15 days after initiation of treatment usually reveals the renal involvement. It is associated with or preceded by fever, skin eruption and blood eosinophilia. Renal insufficiency (RI) is not severe and rarely requires hemodialysis (HD). The course is usually favorable. Rifampicin-induced AIN is observed in two circumstances, either during intermittent treatment or when previous treatment is resumed. Macroscopic hematuria is rare and RI often severe. Anti-rifampicin anti-bodies are usually found. 2) ATIN due to direct toxicity. Several classes of antibiotics may be responsible: cephalosporins, polymyxins or cyclins, but it is usually observed with aminoglycosides (AG). The incidence of renal involvement due to the latter group is estimated to be 4 to 10%. Nephrotoxicity is initially reflected by polyuria, tubular proteinuria and increased enzymuria, followed by cylindruria and reduced glomerular filtration. HD is rarely required. The proximal tubule is predominantly affected; pathological findings are disappearance of the brush border and tubular necrosis. Electronic microscopy shows lysosomal alterations with numerous myelinic bodies. Tubular regeneration occurs within 15 to 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

The lysosomal toxicity of aminoglycosides: a morphometric approach.

Lysosomes of kidney proximal tubule cells have been described as an early target involved in aminoglycoside-induced nephrotoxicity. These organelles concentrate these molecules and are overloaded with osmiophilic lamellar material. Biochemical alterations of lysosomes have already been described. In this study 6 aminoglycosides were given i.p. at the doses of 10 and 50 mg/kg for 4-7-15 days. A morphometric study of the lysosomal system of rat kidney proximal tubules is described first using Delesse's principle on electron micrographics. After aminoglycoside treatment, lysosomal volume rose from 3.3% in controls up to 10% or more of the cell volume. Concomitantly lysosomes were overloaded with myeloid bodies up to 50% or more of their own volume. Individual measurements of lysosome sections were performed on micrographics: perimeter and area. Size distributions were compared to each other using the Kolmogorov-Smirnov statistical test. Since the observed distribution could not be compared with a normal, Poisson, or any other theoretical distribution, the size distribution of perimeters has been successfully likened to a sum of individual normal subpopulations, the means of which follow a geometrical progression of rate square root 2 from a constant value of 1.23 micron, with standard errors of 15% of their respective mean value. When converted to membrane area values the progression rate becomes 2 and suggests fusion of identical size lysosomes during their intracellular life.

Renal histological and biochemical changes induced in the rat by dibekacin.

Among presently available aminoglycosides, dibekacin has the least toxic effect on the functions of the cochlea and the vestibule. We investigated the potential nephrotoxicity of dibekacin at various dose levels and durations of treatment. In the rat, the injection of high doses (50 mg/kg for 8 days) produced: 1) a reduction in renal function and the onset of cellular necrosis; 2) the appearance of myeloid bodies in the cells of the proximal tubule; 3) accumulation of the drug in the renal cortex at a concentration of 4.4 micrograms/mg of protein; 4) a reduction in the lysosomal latency of N-acetyl-beta-D-glucosaminidase; and 5) disorders of the activity of cortical enzymes cathepsin B and sphingomyelinase. The effect of dibekacin is similar to that of the other aminoglycosides, but it would seem to be less nephrotoxic than gentamicin.

Comparative nephrotoxicity of four aminoglycosides: biochemical and ultrastructural modifications of lysosomes.

In 1982, aminoglycosides still are widely prescribed and considered indispensable for the treatment of severe gram-negative infections. All the aminoglycosides are nephrotoxic, but both experimental works and clinical investigations indicate that they do not all have the same nephrotoxic potential. Within the renal tubular cell in several animal species and in man, the initial and the most extensive changes are those that occur in the lysosomes. We compared the effects of gentamicin, tobramycin, netilmicin and, amikacin on (a) lysosomal structural latency, (b) the activity of several enzymes, either lysosomal or those contained in the proximal tubular cell brush border, and (c) the accumulation of myeloid bodies in the lysosomes. From our results, it appears that gentamicin is the aminoglycoside that induces the greatest number of lysosomal changes whereas amikacin induces the least, with the effects of netilmicin and tobramycin quite close to those of amikacin. Other works comparing the nephrotoxicity of aminoglycosides reveal the same high nephrotoxic potential of gentamicin.

Influence of dosage regimen on experimental tobramycin nephrotoxicity. A biochemical approach.

Many factors play a role in aminoglycoside nephrotoxicity. To study the influence of dosage regimens, Wistar rats were injected for 8 days with a total daily dose of 10, 20, or 50 mg/kg tobramycin intraperitoneally either in one single (1) or in thrice (3) daily injections. The results were different according to the dose. With 10 or 20 mg/kg, serum creatinine did not increase. Alanine aminopeptidase activities decreased whatever the rhythm of administration. gamma-Glutamyl-transpeptidase and N-acetyl-beta-D-glucosaminidase activities were unchanged. Sphingomyelinase and cathepsin B activities were diminished with three injections and not affected with one injection. Renal tobramycin content was not significantly different with (1) or with (3). Lysosomal structural latency was decreased in rats treated three times a day. With 50 mg/kg, serum creatinine was significantly increased and was higher with one injection daily. Alanine aminopeptidase decreased with only one injection daily and gamma-glutamyl-transpeptidase was unchanged. N-acetyl-beta-D-glucosaminidase was increased with (1) and with (3). Sphingomyelinase and cathepsin B activities were significantly decreased. No differences were observed in rats treated once or thrice daily. Renal tobramycin content was similar with (1) and (3). The lysosomal structural latency was significantly decreased and to the same degree for both regimens. In conclusion, based on this study and on other related studies in the literature it is presently very difficult to determine the real relationship between dosage frequency and development of nephrotoxicity.

[Functional, histological, biochemical renal modifications. Comparative study of dibekacin, gentamicin, tobramycin, netilmicin and amikacin]. / Modifications fonctionnelles, histologiques, biochimiques rénales. Etude comparative entre dibékacine, gentamicine, tobramycine, nétilmicine et amikacine.

In this study, we evaluate the nephrotoxic potential of dibekacin (D) compared to gentamicin (G), tobramycin (T), amikacin (A) and netilmicin (N). The mean features of aminoglycoside nephrotoxicity are: a lysosomal membrane fragilization, a lysosomal phospholipidosis characterized by a decrease activity of sphingomyelinase, an increase lysosomal volume with both an increase of individual size and an increase number of lysosomes, a cell necrosis and renal failure. We have quantified these parameters biochemically and morphometrically. We can classify, considering doses and durations, the aminoglycosides as gentamicin greater than or equal to netilmicin greater than dibekacin = tobramycin greater than amikacin for decreasing nephrotoxic incidence.