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Biomedical subjects

C Carbon

Publications and source records attributed to C Carbon.

At least 271 records · Page 15Linked to original sources
PubMed1985

Renal disposition of gentamicin, dibekacin, tobramycin, netilmicin, and amikacin in humans.

The tubular disposition of five aminoglycosides was studied in humans to establish a possible relationship between tubular reabsorption and the nephrotoxicity that has been described in the literature. Thirty-three healthy male volunteers received a continuous intravenous infusion of isotonic saline with inulin, followed 1 h later by inulin plus gentamicin, dibekacin, tobramycin, netilmicin, or amikacin (1 mg/kg per h) or amikacin (4 mg/kg per h) over a period of 2 h. Brain-stem-evoked response audiometry was performed both before and at the end of each infusion. The latency of wave V remained constant whichever antibiotic was considered. The glomerular filtration rate did not vary significantly during the infusion of each drug. The percent fractional excretion was 79 +/- 6, 81 +/- 22, 85 +/- 5, and 99 +/- 9 for gentamicin, dibekacin, tobramycin, and netilmicin, respectively, and 83 +/- 4 and 124 +/- 13 for amikacin at concentrations of 1 and 4 mg/kg per h, respectively. Net balance and renal clearance were similar for the five aminoglycosides when administered at a rate of 1 mg/kg per h. With gentamicin only, fractional excretion was correlated with the urinary flow rate. We can conclude that (i) gentamicin, generally considered the most nephrotoxic agent, had the highest degree of net reabsorption; (ii) netilmicin exhibited a net zero tubular balance; (iii) amikacin had different patterns of tubular disposition according to the dose, i.e., reabsorption at 1 mg/kg per h and secretion at 4 mg/kg per h, raising the hypothesis of a saturable process of reabsorption; and (iv) these differences in tubular reabsorption could account at least in part for the known different nephrotoxic potentials of these five aminoglycosides in humans.

Adult↗
PubMed1985

Effects of urinary pH on renal interactions between probenecid and cefsulodin in rabbits.

The effect of urinary pH on renal interaction of cefsulodin and probenecid was tested in rabbits. Probenecid was reabsorbed in acidic urine (fractional excretion [FE] = 8 +/- 4%) and secreted in alkaline urine (FE = 492 +/- 258%). Renal excretion of cefsulodin alone was not affected by the urinary pH (FE = ca. 100%). In acidic urine, probenecid significantly reduced tubular secretion of cefsulodin (FE = 74 +/- 8%). An inverse pattern was observed in alkaline urine (FE = 122 +/- 18%).

Animals↗
PubMed1985

Comparison of penicillin and vancomycin, individually and in combination with gentamicin and amikacin, in the treatment of experimental endocarditis induced by nutritionally variant streptococci.

Six different antibiotic treatment regimens were compared for efficacy in rabbits with endocarditis induced by inoculation with a nutritionally variant strain of streptococcus. Seven untreated animals, sacrificed at day 11, had vegetations containing 8.89 +/- 1.35 log10 CFU/g, none of which was sterile. The vegetations from the rabbits in all treated groups had bacterial titers significantly lower than those of the controls (P less than 0.001). Vegetations from penicillin-treated animals averaged 5.14 +/- 1.00 log CFU/g, and no vegetations were sterile. Treatment with penicillin plus gentamicin or amikacin was more effective than treatment with penicillin alone, resulting in 3.99 +/- 0.94 log CFU/g of vegetation and sterile lesions in 5 of 12 animals. Treatment with vancomycin alone was as least as efficient as that with penicillin plus an aminoglycoside, resulting in an average of 3.33 +/- 0.96 log CFU/g of vegetation and sterile lesions in five of eight animals. Treatment with vancomycin plus an aminoglycoside was not superior to treatment with vancomycin alone, resulting in an average of 3.68 +/- 1.37 log CFU/g of vegetation and sterile lesions in 8 of 13 animals. These in vivo results correlated poorly with the in vitro susceptibility of the strain to the various antibiotics, as measured by the time-kill method. These results support the current practice of using vancomycin as alternative therapy when a penicillin-aminoglycoside combination is ineffective or contraindicated in patients with endocarditis caused by nutritionally variant streptococci.

Amikacin↗
PubMed1985

[Lead encephalopathy with thrombosis of the superior longitudinal sinus].

A 32 year old obese, diabetic and hypertensive woman presented with signs of increasing intracranial pressure: diplopia, partial lateralised Jacksonian seizures followed by alternating post-ictal hemiplegia. She was also anaemic. Investigation revealed lead poisoning and thrombosis of the superior sagittal sinus. She recovered rapidly with heparin and calcium EDTA therapy, except for persistent optic atrophy due to the papilloedema. The authors discuss the relation of lead encephalopathy and dural sinus thrombosis, and the contribution of each condition to this patient's clinical symptoms.

Adult↗
PubMed1984

Pefloxacin in rabbits: protein binding, extravascular diffusion, urinary excretion and bactericidal effect in experimental endocarditis.

The serum protein binding, extravascular diffusion and urinary excretion of pefloxacin were studied in rabbits. The effect of furosemide on the urinary excretion of pefloxacin was investigated. In an experimental model of Escherichia coli endocarditis, diffusion into heart valves and infected vegetations and bactericidal effect of pefloxacin were also studied. We observed a serum protein binding of 25%. Extravascular concentrations found were within the range of the minimal inhibitory concentrations for most susceptible strains. Pefloxacin appeared to be reabsorbed by renal tubules (fractional excretion: 61 +/- 21%). Furosemide significantly increased the renal excretion of pefloxacin through a tubular process. We observed a good penetration of pefloxacin into normal heart valves and infected vegetations. Pefloxacin reduced the colony counts in infected vegetations after seven im injections of the drug (given as 15 mg/kg/12 h).

Animals↗
PubMed1984

Gentamicin, netilmicin, dibekacin, and amikacin nephrotoxicity and its relationship to tubular reabsorption in rabbits.

The role of the tubular reabsorption of aminoglycosides in nephrotoxicity was considered. The tubular reabsorption rate, fractional reabsorption, and net balance, expressed as the excreted to infused aminoglycoside ratio, were concomitantly studied in male rabbits by continuous infusion of gentamicin, netilmicin, dibekacin, and amikacin. Aminoglycoside nephrotoxicity was evaluated by creatinine levels in serum and pathological renal damage after 14 days of a low- or high-dose regimen, comprising either eight, hourly intramuscular injections of gentamicin, netilmicin, or dibekacin (4 mg/kg) or amikacin (16 mg/kg); twelve, hourly intramuscular injections of gentamicin, netilmicin, or dibekacin (15 mg/kg) or amikacin (60 mg/kg); or injections of saline for the control group. Aminoglycosides exhibited three degrees of tubular reabsorption: gentamicin had the highest, netilmicin had the lowest, and dibekacin and amikacin had intermediate degrees of reabsorption. Nephrotoxicity associated with alteration in renal histology was observed with gentamicin and, to a lesser extent, with dibekacin in the high-dose regiment. No nephrotoxicity was noted with netilmicin or amikacin compared with the control group. Concentrations of the aminoglycosides in renal cortex and serum were not predictive of renal toxicity. Except for amikacin, which appeared to exhibit the lowest intrinsic renal toxicity, nephrotoxicity was correlated with the tubular reabsorption of each aminoglycoside. It was concluded that aminoglycoside renal toxicity can be determined by two major factors: importance of transport into tubular cells and intrinsic intracellular toxicity.

Amikacin↗
PubMed1984

Effects of furosemide, piretanide, and water loading on urinary excretion of cefazolin in humans.

Antibiotics and diuretics are often prescribed concomitantly for humans. We compared the effects of two potent loop diuretics, furosemide and piretanide, with those of water loading on the urinary excretion of cefazolin. During a continuous infusion of inulin and cefazolin (10 mg/kg per h), six healthy male volunteers received a single intravenous injection of furosemide (0.3 mg/kg) or piretanide (0.1 mg/kg) or again an oral water load of 15 ml/kg over a 20-min period. In vitro, furosemide at all concentrations tested significantly reduced by about 10% the percentage of cefazolin bound to serum proteins. Piretanide exhibited such an effect only at a concentration of 2 micrograms/ml. Furosemide, piretanide, and water loading significantly and similarly increased the ratio of excreted to infused cefazolin up to 2 h after the injection of diuretic or after oral water intake. In each of the three parts of the experiment, the increase of the urinary flow rate was similar when compared with the control values. Furosemide significantly increased the cefazolin filtered load during the same time. Piretanide significantly enhanced the absolute rate of net cefazolin tubular secretion. Water loading increased the urinary excretion of cefazolin, probably through a reduction in tubular reabsorption. These results suggest that (i) furosemide and piretanide as well as water loading are capable of enhancing renal excretion of cefazolin by different complex mechanisms; (ii) cefazolin undergoes a bidirectional tubular transport; (iii) piretanide might act on the proximal tubule in addition to its main site of action on Henle's loop; and (iv) the effects of both diuretics and of water loading are unlikely to affect in vivo antibiotic activity in humans.

Adult↗
PubMed1984

Renal disposition of ceftazidime illustrated by interferences by probenecid, furosemide, and indomethacin in rabbits.

Excretion of ceftazidime (C), a new cephalosporin antibiotic, has been reported to occur unexpectedly through glomerular filtration only, without being significantly affected by probenecid. We investigated renal tubular disposition of C in rabbits by calculating its rates of fractional excretion, net tubular secretion, and absolute excretion. During continuous intravenous infusion of C, 3 mg of furosemide (F), 15 mg of probenecid (P), or 2 mg of indomethacin (I) per kg was injected intravenously as a bolus. Equilibrium dialysis showed that the percentage of C bound to serum proteins (14 +/- 5%) was not altered by F, P, or I. Fractional excretion of C was 94 +/- 22, 65 +/- 21, 182 +/- 36, and 98 +/- 3% for the drug given alone and after injection of F, P, and I, respectively. For 15 min after P injection, we observed net tubular secretion of C (404 +/- 276 micrograms/min). The C absolute excretion rate was significantly reduced by I compared with the absolute excretion rate for the control (405 +/- 104 versus 696 +/- 157 micrograms/min). We conclude that (i) C undergoes bidirectional transport in the nephron, revealed by the effects of F and P, with a nil net C balance; (ii) F and P have opposite unexpected effects on tubular handling of C, possibly due to competition for C secretion processes; (iii) I reduces C excretion solely by decreasing its glomerular-filtered load; and (iv) tubular handling of C differs from that of previously studied cephalosporins.

Animals↗
PubMed1984

[Theoretical objective evaluation of the value of a diagnostic criterion. Application to antinuclear antibodies for the diagnosis of systemic lupus erythematosus].

The value of various types of anti-nuclear antibodies (ANA) for the diagnosis of systemic lupus erythematosus (SLE) was calculated in a population of adult patients with chronic polyarthritis. The aim of this study was to demonstrate the value of calculating the predictive value of a test applied to a particular clinical situation. It was conducted on the basis of epidemiological and laboratory data from the literature. The calculations show that the presence of ANA in immunofluorescence only slightly increases the probability of the diagnosis of SLE (7%). On the other hand, these antibodies are an example of a very sensitive test which, when it is negative allows the diagnosis to be almost totally excluded, while anti-Sm antibodies are very specific and their presence allows the diagnosis to be confirmed. Anti-nDNA antibodies have intermediate features, but their diagnostic performance increases with the level of radioactive n-DNA binding chosen as the level of positivity; in this example, for a level of binding of more than 50%, the predictive value of anti-nDNA antibodies is equivalent to that of anti-Sm antibodies.

Adult↗
PubMed1983

[From serum pharmacokinetics to extravascular pharmacokinetics of antibiotics. Importance of protein binding].

Serum and urinary concentrations of antibiotics are not predictive of their extravascular distribution. Data from an animal model giving access to an extravascular fluid have demonstrated the effects of protein binding on the extravascular diffusion of cephalosporins. A high percentage of protein binding delays extravascular distribution and facilitates accumulation from repeated doses. Moreover, strongly bound drugs may reduce the number of protein-bound cephalosporin molecules by competing for binding sites and interfere with the extravascular distribution of these antibiotics without modifying their serum levels.

Animals↗
PubMed1983

[Late recurrence of Horton's disease with sicca syndrome].

The authors report the case of an eighty-three-year-old woman with giant-cell arteritis who experienced recurrence five years after the withdrawal of corticosteroids which had been given for four consecutive years. This recurrence, demonstrated by arterial biopsy, was accompanied with Sjögren disease proven upon histological examination. With reference to this case-report, the various possible courses of protracted giant-cell arteritis are discussed; relapses occurring more than one year after therapy is discontinued are exceptional.

Aged↗
PubMed1982

[Treatment of urinary tract infections by dibekacin].

In this cooperative trial, 181 patients with various urinary tract infections were treated by dibekacin, a new hemi-synthetic aminoglycoside. Clinical and bacteriological results confirm the efficacy of dibekacin in this indication. Local and systemic tolerance, and thus renal and cochleo-vestibular, were very satisfactory.

Dibekacin↗