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C Carbon

Publications and source records attributed to C Carbon.

At least 163 records · Page 9Linked to original sources
PubMed1994

In vivo activity of interferon-gamma in combination with amphotericin B in the treatment of experimental cryptococcosis.

The effect of recombinant interferon-gamma (rIFN-gamma) on Cryptococcus neoformans infection was investigated in vivo. BALB/c mice were injected intravenously with 2 x 10(6) C. neoformans. rIFN-gamma alone (10 micrograms intraperitoneally 18 h before, at, 24 h after infection) significantly increased the survival and decreased the colony-forming unit counts in the lungs compared with untreated mice. rIFN-gamma association significantly enhanced the effect of a single dose of amphotericin B (0.25 mg/kg 24 h after infection) to prolong mouse survival and to reduce colony counts in the brain. Tumor necrosis factor-alpha levels, measured in spleen 3, 6, and 24 h after infection, were not increased by rIFN-gamma. These results suggest that exogenous rIFN-gamma might improve the effect of antifungal therapy during cryptococcosis.

Amphotericin B↗
PubMed1994

Conditions for the emergence of resistance to cefpirome and ceftazidime in experimental endocarditis due to Pseudomonas aeruginosa.

The conditions for the emergence of resistance to cefpirome and ceftazidime were studied in rabbits with experimental aortic endocarditis due to Pseudomonas aeruginosa. The MIC of cefpirome was 16 mg/L and that of ceftazidime was 4 mg/L. Resistant mutants with MICs of > or = 64 mg/L were obtained in vitro to cefpirome after a single passage and to ceftazidime after five passages. A single dose of 50 mg/kg intramuscularly gave mean peak serum concentrations of 110.0 +/- 31.7 mg/L for cefpirome compared with 67.7 +/- 21.4 mg/L for ceftazidime and the half-lives were 1.2 +/- 0.1 h and 2.1 +/- 0.4 h, respectively. After treating infected rabbits for 4 days with various dosing regimens, resistant strains were only detected in those animals in which the time that the serum concentration exceeded the MIC was less than half of the dosing interval. There was no evidence of emergent resistance when the serum concentrations exceeded the MIC for a longer period nor when amikican was combined with the cephalosporins on the first day of therapy. Moreover, once differences in MICs and pharmacokinetics were taken into account, both antibiotics had a similar propensity to induce resistance.

Animals↗
PubMed1994

Toxoplasma gondii infection in advanced HIV infection.

OBJECTIVE: To study Toxoplasma encephalitis (TE) in advanced HIV infection, including predictive factors, possible prophylactic regimens and impact on survival. DESIGN: Epidemiological analysis of data collected prospectively during the Alpha study, a double-blind, randomized clinical trial, comparing two doses of dideoxyinosine in patients with advanced HIV disease. PATIENTS: First episode of TE occurred in 75 out of 499 patients participating in the trial. METHODS: Kaplan-Meier estimates and semi-parametric Cox's model were used. RESULTS: A low CD4 cell count and a positive Toxoplasma serology were strongly predictive of the occurrence of TE. In patients with CD4 counts < 100 x 10(6)/l and a positive Toxoplasma serology at entry to the study, the 12-month TE incidence was 25.4%. Patients who were receiving at entry any of the following potentially antitoxoplasmic drugs: trimethoprim-sulphamethoxazole, pyrimethamine, dapsone, pyrimethamine-sulphadoxine or sulphadiazine, had a lower TE incidence than those who were not; 6.2 versus 18.8%, respectively (P < 0.001). The rate of survival 12 months after TE was 29.6%. Even after adjusting the major prognostic covariates, TE was predictive of death (P < 0.001; relative risk, 1.8). CONCLUSIONS: The high HIV incidence, morbidity and mortality in high-prevalence areas suggests that primary prophylaxis should be given in patients at high risk for toxoplasmic reactivation.

AIDS-Related Opportunistic Infections↗
PubMed1994

In vitro renal toxicity and in vivo therapeutic efficacy in experimental murine cryptococcosis of amphotericin B (Fungizone) associated with Intralipid.

We compared the experimental toxicities and activities of deoxycholate amphotericin B (d-AmB) dissolved in glucose (Dd-AmB) or mixed with 20% Intralipid (ILd-AmB). In vitro, ILd-AmB against renal tubular cells in primary culture. In vivo, the toxicities and activities of Dd-AmB and ILd-AmB were studied in DBA2 mice with cryptococcosis. The maximum tolerated dose of intravenously administered d-AmB, i.e., the dose that induced less than 15% mortality because of toxicity, was 1.7 to 2.5 times higher when it was administered as ILd-AmB than when it was administered as Dd-AmB. Both treatments given intravenously at the same dose were equivalent for improving the survival of mice and reducing CFU counts in infected tissue, but at maximum tolerated doses, ILd-AmB (2 mg/kg of body weight) was more effective than Dd-AmB (0.8 to 1.2 mg/kg). AmB concentrations in spleen, liver, lung, and kidney were measured by high-pressure liquid chromatography 4 and 24 h after a single injection of 1.2 mg of Dd-AmB per kg, 1.2 mg of ILd-AmB per kg, or 2 mg of ILd-AmB per kg. In a given organ, AmB levels were similar after administration of 1.2 mg of Dd-AmB or ILd-AmB per kg but were significantly higher after administration of 2 mg of ILd-AmB per kg. The lower level of toxicity of ILd-AmB might be explained by circular dichroism experiments, showing that ILd-AmB contained 10-fold less soluble oligomeric AmB, which is believed to be the toxic form of the drug, than Dd-AmB. We conclude that ILd-AmB is as efficient as Dd-AmB and is better tolerated than Dd-AmB in mice with experimental cryptococcosis. By allowing higher doses of AmB to be infused, Intralipid enhances AmB concentrations in infected sites, and thus the therapeutic activity of the drug.

Amphotericin B↗
PubMed1994

In vivo activities and penetration of the two components of the streptogramin RP 59500 in cardiac vegetations of experimental endocarditis.

We evaluated the in vivo activity and the diffusion of radiolabelled RP 57669 (RPI) and RP 54476 (RPII), the two components of the injectable streptogramin RP 59500, alone or in combination, in aortic vegetations from experimental endocarditis in rabbits. RPI and RPII demonstrated in vitro bacteriostatic and bactericidal synergy against a clinical strain of Staphylococcus aureus resistant to methicillin and susceptible to erythromycin. In experimental staphylococcal endocarditis, RP 59500 was as effective as vancomycin and significantly more effective than RPI (P < 0.01) and RPII (P < 0.05). Autoradiography studies showed different patterns of distribution into cardiac vegetations infected with Streptococcus sanguis for [14C]RPI and [14C]RPII. [14C]RPI was homogeneously distributed throughout the vegetations whereas [14C]RPII showed a decreasing gradient of concentration between the periphery and the core of the vegetation, with an approximately 2:1 ratio. [14C]RPI diffused approximately 2 to 4 times more than [14C]RPII into the core of the vegetations. Since the injected ratio of RPI and RPII is 30:70 in RP 59500, the actual RPI:RPII ratio in the core of the vegetation may range from 0.8 to 1.7, a ratio which remains compatible with the in vivo synergism demonstrated between the two components.

Animals↗
PubMed1994

Intestinal elimination of ciprofloxacin in rabbits.

The intestinal transepithelial elimination of ciprofloxacin was studied in a rabbit model. Jejunal, ileal, and cecal segments along with their intact blood vessels were isolated and perfused, and their contents were collected over a 120-min period following administration of a single parenteral dose of 27 mg of ciprofloxacin per kg of body weight. The intestinal elimination rates of ciprofloxacin were 0.126 +/- 0.084, 0.235 +/- 0.22, and 0.11 +/- 0.084 micrograms.min-1.cm-2 for the jejunal, ileal, and cecal segments, respectively. The calculated fractions of ciprofloxacin eliminated were 3.3 mg from the jejunum and 13.8 mg from the ileum, representing 19% of the administered dose. Additional amounts of 2.5 to 3.7 mg or 4.9 to 7.3% of the administered dose were eliminated from the cecum. Elimination was probably not due to a passive diffusion process but rather due to an active transepithelial transport. This intestinal elimination pattern of ciprofloxacin may explain the unusual activity of the fluoroquinolones in modifying the intestinal flora.

Animals↗
PubMed1994

Influence of antimicrobial therapy on kinetics of tumor necrosis factor levels in experimental endocarditis caused by Klebsiella pneumoniae.

The kinetics of tumor necrosis factor (TNF) levels in serum during therapy with cell wall-active agents (ceftriaxone, imipenem) and gentamicin were investigated in rabbits with experimental endocarditis caused by an isogenic pair of Klebsiella pneumoniae strains: a TEM-3 beta-lactamase-producing strain (KpR) or its susceptible variant (KpS). In vitro, KpR was resistant to ceftriaxone and was susceptible to gentamicin and imipenem, while KpS was susceptible to all three antibiotics. Serum TNF levels were determined in control rabbits hourly after bacterial inoculation and then daily; they were determined in treated animals hourly after the first antibiotic injection and then daily during a 4-day therapy with either imipenem (60 mg/kg of body weight four times daily), ceftriaxone (75 mg/kg once daily), or gentamicin (4 mg/kg once daily) alone or in combination with ceftriaxone. After a transient peak (10.2 +/- 3.1 ng/ml) at 90 min following bacterial challenge, serum TNF levels remained low and stable in control animals. The peak in the serum TNF levels occurred 4 h after the first antibiotic injection and with ceftriaxone was significantly higher (P < 0.05) against KpS (1.99 +/- 0.52 ng/ml) than against KpR (1.40 +/- 0.17 ng/ml). Against the KpR strain, the levels observed with ceftriaxone were significantly higher (P < 0.05) than those obtained with the other therapeutic regimens (0.70 to 0.80 ng/ml). On the day of sacrifice, effective regimens were associated with low TNF levels. We concluded that TNF production depends on (i) the antiobiotic's mechanism of action and the susceptibility of the strain at the early phase of therapy, without any effect of the rapidity of bacterial killing, and (ii) the final reduction of the bacterial count at a later stage of therapy.

Animals↗
PubMed1994

Dextranase enhances antibiotic efficacy in experimental viridans streptococcal endocarditis.

In endocarditis, exopolysaccharide production by viridans streptococci has been associated with delayed antimicrobial efficacy in cardiac vegetations. We compared the efficacies of temafloxacin alone and in combination with dextranase, an enzyme capable of hydrolyzing 20 to 90% of the bacterial glycocalyx, in a rabbit model of endocarditis. In in vivo experiments, rabbits were infected intravenously with 10(8) Streptococcus sanguis organisms and were treated 6 days later with temafloxacin (50 mg/kg of body weight intramuscularly twice a day) alone or combined with dextranase (1,000 U per rabbit per day intravenously). After 4 days of treatment (day 11), the animals were sacrificed and vegetations were quantitatively cultured. For ex vivo experiments, rabbits were infected as stated above and, on day 11, vegetations were excised aseptically and incubated in vitro in rabbit serum alone (control) or with temafloxacin or temafloxacin plus dextranase at concentrations similar to peak levels in plasma. In vitro, dextranase alone had no antimicrobial effect. In vivo and ex vivo, temafloxacin combined with dextranase was more effective than temafloxacin alone (P < 0.05). Our results suggest that dextranase is able to increase the effects of temafloxacin by reducing the amount of bacterial glycocalyx in infected vegetations, as confirmed in vitro by electron microscopy showing a markedly reduced amount of glycocalyx and a more clearly visible fibrin matrix.

Animals↗
PubMed1994

Influence of diet on experimental toxicity of amphotericin B deoxycholate.

The effects of pre- and postprandial levels of lipids in serum on the experimental in vivo and in vitro toxicities of amphotericin B deoxycholate (AmB-d) were studied. Normal OF1 mice were tested at baseline, after normal feeding, after 3 h of fasting, or after a sequence of feeding and fasting and vice versa. The 50% lethal dose (LD50) of AmB-d was significantly higher in fed mice than in mice which fasted or at baseline (2.38 +/- 0.12 versus 1.53 +/- 0.2 and 1.50 +/- 0.1 mg/kg of body weight, respectively; P < 0.05). When different nutritional regimens were alternated over a short period, the level of in vivo AmB-d toxicity was dictated by the last feeding regimen. Serum triglycerides, but not cholesterol in very-low-density and low-density lipoproteins, correlated significantly (P < 0.01) with the LD50 of AmB. In vitro experiments showed that the addition of human serum reduced AmB-d-induced toxicity against human erythrocytes, but serum drawn after fasting was less protective than postprandial serum. However, neither serum decreased the in vitro activity of AmB-d against Candida albicans. Circular dichroism, a method that enables the amount of free AmB to be measured, showed that both mouse and human total serum lipoproteins bound more AmB-d when serum was isolated postprandially than when it was obtained after fasting. Our results show that AmB-d toxicity is reduced by feeding-induced modifications in serum lipids. The influence of food intake on the clinical toxicity of the drug merits being investigated.

Amphotericin B↗
PubMed1993

[Acquired data on the antibiotic treatment of bacterial endocarditis on native or prosthetic valves].

Antimicrobial therapy of infective endocarditis is based on periodically updated expert recommendations that derive from both clinical and experimental data. Streptococcal and enterococcal endocarditis should be treated intravenously with a combination of penicillin+aminoglycoside in the absence of allergy to penicillin. The choice of either penicillin or ampicillin, the dose and the length of treatment plainly depend on susceptibility of streptococcal strain to penicillin. In patients allergic to penicillin, vancomycin is the optimal choice. The treatment of native valve meticillin-susceptible staphylococcal endocarditis is based on a combination of oxacillin or cefamandole+aminoglycoside. Vancomycin is recommended in case of allergy to penicillin and in meticillin resistant staphylococcal endocarditis. Prosthetic valve staphylococcal endocarditis are often due to meticillin-resistant coagulase negative staphylococci. Therefore they should be treated with vancomycin in combination with rifampicin and an aminoglycoside unless the strain is resistant to either of these 2 antibiotics. For the treatment of culture-negative endocarditis, different situations should be considered: in native valve endocarditis, the possible responsibility of deficient streptococci justifies an ampicillin+aminoglycoside combination; in recently implanted (< 1 year) prosthetic valve endocarditis a combination of vancomycin+rifampicin+aminoglycoside should be used because of the high probability of meticillinresistant staphylococci: if prosthetic valve is implanted for more than a year endocarditis may be due to streptococci, staphylococci and fastidious gram-negative bacilli; a combination of vancomycin+aminoglycoside +/- third generation cephalosporin is therefore recommended.

Anti-Bacterial Agents↗
PubMed1993

[Fluoroquinolones, 10 years later].

During the last few years the fluoroquinolone class has been profoundly reshaped. The development of mutation-acquired resistance, principally from staphylococci and Gram-negative bacteria responsible for nosocomial infections has restricted the use of these antibiotics as first-line monotherapy to some community-acquired infections (urinary tract, gastrointestinal, sexually transmitted infections), while defects in their antibacterial spectrum (pneumococci, streptococci and anaerobes) have reduced the possibility of use against respiratory infections. Future developments concern compounds that are active against Gram-positive cocci and some intracellular bacteria (e.g. mycobacteria) and possibly against certain parasites. Problems of tolerance are important in clinical trials of the new compounds.

Anti-Infective Agents↗
PubMed1993

[Gaucher's disease type 1: apropos of 17 cases].

Gaucher's disease is characterized by accumulation of glucocerebroside (caused by an autosomally inherited deficiency of glucocerebrosidase) in the cells of the reticuloendothelial system. We report the clinical, laboratory, radiologic features of 17 patients with type 1 Gaucher's disease.

Adult↗
PubMed1993

[Course of a case of Gaucher's disease type 1 treated over a year with glucocerebrosidase (Cérédase)].

Gaucher's disease is caused by a deficiency of glucocerebrosidase. Enzyme replacement therapy with glucocerebrosidase (Ceredase) is available in France since 1991. We report the clinical effectiveness in a woman with type 1 Gaucher's disease treated with the enzyme for one year. Hepatomegaly regressed, bone pain decreased but improvement of severe skeletal manifestations were slow and incomplete.

Female↗
PubMed1993

Experimental endocarditis: a review of its relevance to human endocarditis.

Bacterial endocarditis is a difficult-to-cure infection, owing to (i) poor penetration of antibiotics into infected vegetations; (ii) altered metabolic state of bacteria within the lesion; (iii) absence of adequate host-defence cellular response which could cooperate with antibiotic action. The contribution of infection models to definition and improvement of therapeutic regimens of endocarditis in man remains of great importance because of the difficulties encountered in clinical trials. The advantage of the experimental model is that besides the fact that it closely simulates the characteristics of the infection in humans, it provides clear endpoints which allow statistical comparisons among different therapeutic regimens: number of bacteria/g of tissue, frequency of emergence of resistance, positivity of blood cultures, death vs survival rates, and percentage of relapses after treatment has been stopped. All these parameters are more sensitive and more easy to use than in man. The infection model has definitively established that bactericidal therapy is warranted and that in-vitro susceptibility tests, especially those evaluating the killing rate, have a good predictive value for the therapeutic outcome. Three main aspects are discussed for their influence on human therapy (i) the kinetics of antibiotic diffusion into vegetations, with a special reference to the data obtained by autoradiography, (ii) the specificity of some pharmacodynamic aspects of antibiotics in endocarditis, including the clinical consequences of these two parameters on antibiotic dosing regimens and length of therapy, and (iii) in-vivo synergy. This phenomenon involves a variety of mechanisms which are difficult or even impossible to analyse on the sole basis of in-vitro data: enhanced bactericidal activity (beta-lactam-aminoglycoside), prevention of emergence of resistance (as demonstrated for rifampin, quinolones or fosfomycin) and, as shown with rifampin or quinolones, 'pharmacokinetic synergy'. Animal models have helped to define the importance of antibiotic dosing strategies to achieve in-vivo synergy which appears as essential to increase the rate of both bacteriological and clinical cure rate.

Animals↗
PubMed1993

Influence of the pre-treatment duration of infection on the efficacies of various antibiotic regimens in experimental streptococcal endocarditis.

The influence of the pre-treatment duration of infection on the efficacies of three different antibiotic regimens was investigated in a rabbit model of subacute endocarditis caused by a novel, nutritionally-variant species, Streptococcus adjacens strain GaDT. Treatment was initiated either 6 or 10 days after bacterial inoculation (days 7 and 11 respectively) and comprised procaine penicillin (150,000 IU/kg bd), alone or combined with tobramycin (12 mg/kg od), teicoplanin (10 mg/kg bd), all administered by the intramuscular route for 4 days. The MICs and MBCs of penicillin, tobramycin and teicoplanin were 0.015 and 1 mg/L, 8 and 16 mg/L and 0.25 and 256 mg/L respectively. In the control rabbits, the mean (+/- S.D.) weights of the vegetations were 25 +/- 16 mg on day 7 and 45 +/- 34 mg on day 11 (P = 0.06). The mean (+/- S.D.) reductions in the number of cfu in the vegetations of the treated groups of animals after completion of therapy which had been started on days 7 and 11, compared with the mean numbers of cfu in the vegetations of the untreated controls on days 7 and 11 (delta log10 cfu/g), were 4.0 +/- 1.3 and 2.1 +/- 1.5 respectively for penicillin (P < 0.05), 3.2 +/- 1.8 and 2.4 +/- 1.8 respectively for teicoplanin and 5.4 +/- 1.2 and 5.2 +/- 1.2 respectively for the combination of penicillin and tobramycin. The increase in the size of the vegetations and changes in the metabolism of the bacteria within the vegetations between days 7 and 11, as demonstrated by electron microscopy, might explain why penicillin was more effective earlier in the course of the disease and why the influence of the duration of infection before treatment was initiated, varied according to the antibiotic regimen. These results suggest that the use of bactericidal regimens, such as the combination of penicillin and tobramycin, which are equally effective in reducing the bacterial counts in vegetations which have been infected for both long and short periods could minimize the risk of relapse in patients with endocarditis in whom there have been long delays before initiating treatment and/or who have large vegetations.

Animals↗
PubMed1993

Fusidic acid alone or in combination with vancomycin for therapy of experimental endocarditis due to methicillin-resistant Staphylococcus aureus.

The usefulness of fusidic acid, alone or combined with vancomycin, was investigated for the therapy of experimental endocarditis caused in rabbits by a methicillin-resistant strain of Staphylococcus aureus. In vitro killing curves showed an indifferent interaction between the two antibiotics. In vivo, vancomycin alone was as effective as a vancomycin-fusidic acid combination (P < 0.05 versus control animals). No resistance to fusidic acid emerged during combination therapy. Fusidic acid alone was not effective. Resistance emerged in 5 of 12 animals treated with fusidic acid alone and was responsible for antibacterial failure. Fusidic acid alone was effective (P < 0.001) and did not select resistant strains if therapy was started when animals retained a smaller inoculum. We concluded that the vancomycin-fusidic acid combination exhibited no advantage over vancomycin alone in this model.

Animals↗