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Biomedical subjects

F Caron

Publications and source records attributed to F Caron.

At least 55 records · Page 3Linked to original sources
PubMed1995

In vitro interactions between different beta-lactam antibiotics and fosfomycin against bloodstream isolates of enterococci.

The effects of 16 different beta-lactam-fosfomycin combinations against 50 bloodstream enterococci were compared by a disk diffusion technique. Cefotaxime exhibited the best interaction. By checkerboard studies, the cefotaxime-fosfomycin combination provided a synergistic bacteriostatic effect against 45 of the 50 isolates (MIC of cefotaxime at which 90% of the isolates were inhibited, >2,048 micrograms/ml; MIC of fosfomycin at which 90% of the isolates were inhibited, 128 micrograms/ml; mean of fractional inhibitory concentration indexes, 0.195). By killing curves, cefotaxime (at 64 micrograms/ml) combined with fosfomycin (at > or = 64 micrograms/ml) was bactericidal against 6 of 10 strains tested.

Anti-Bacterial Agents↗
PubMed1995

[Differences in efficiency of continuous positive pressure respiration on the diurnal somnolence of patients with sleep apnea/hypoapnea syndrome].

Diurnal hypersomnia was studied in sixteen patients suffering from the sleep apnoea/hypopnoea syndrome (SHAS) Group I, and seventeen snorers Group II. The groups were studied in their basal state then after 51 +/- 14 days of continuous positive pressure (CPP) in Group I with the aid of clinical scores and of multiple latency tests of sleeping episodes (TLME). The patients in Group I presented with increased and pathological diurnal somnolence (TLME = 3.9 +/- 2.45 min) associated with disturbances of oxygen saturation during the course of sleep (a significant reduction of the mean SaO2) and of the pattern of sleep (significant reduction in light slow sleep at the expense of deep slow sleep, with a significant increase in the index of brief arousals). We have found a positive correlation between the initial TLME and the mean SaO2 during the course of sleep (p < 0.05; R = 0.51) without any correlation with other polysomnographic parameters. At the time of the final assessment, the improvement in TLME in the patients of Group I was significant (p < 0.001). However, in a sub-group of patients (BR: n = 7) the TLME were returned to normal using CPP (16.4 +/- 2.21 min) while those in patients in the second sub-group (MR: n = 9) the TLME remained below ten minutes on CPP (6.18 +/- 1.88 min). In the BR subgroup which presented with the most elevated mean initial TLME levels the amplitude of the rise of TLME between the two groups was significantly larger. No initial polysomnographic difference existed between the two sub-groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Arousal↗
PubMed1995

[Metastatic pulmonary choriocarcinoma and pulmonary arteriovenous aneurysm].

Pulmonary metastases from a uterine choriocarcinoma are rare in France. The authors report a case of a 42 years old patient who presented more than four years after her last pregnancy with a metastasis in the left lower lobe due to a uterine choriocarcinoma. There was a favourable outcome after combined treatment with chemotherapy and surgery. The patient had been in hospital eighteen months earlier for a spontaneous left haemothorax secondary to a ruptured intrapleural pulmonary arterio-venous aneurysm (AVV) of the left lower lobe which was treated by embolisation. The aetiology of pulmonary AVV are defined, and the pathophysiology of uterine carcinoma as well as the probable association and pulmonary vascular anomalies are discussed.

Adult↗
PubMed1994

[Celioscopic cholecystectomy. 2 cases of infectious complications].

Despite the low morbidity and mortality of laparoscopic cholecystectomy, trauma and infection have been reported. Such complications can produce a misleading clinical picture, as in two cases we observed. Case 1. A symptomatic 56-year-old female patient underwent laparoscopic cholecystectomy. During the operation, the gall bladder ruptured and the contents had to be aspirated from the abdominal cavity. The patient complained of hepatalgia 2 weeks after the operation, then was not seen again for more than 1 year when fever and hepatalgia did not respond to symptomatic treatment. An inter-hepato-renal collection (6 cm in diameter) was punctured under echography. Aspirate culture yielded Pseudomonas aeruginosa. Adapted antibiotic therapy was unsuccessful and surgery was required to empty the abscess then remove a fibrous conjunctive tissue formation. Case 2. A 55-year-old female patient with a history of complete remission after mammectomy for breast cancer underwent laparoscopic cholecystectomy in 1991. Two days after the operation, fever (39 degrees C) was accompanied by abdominal defence. Biliary peritonitis due to imperfect suture of the bile duct was repaired followed by peritoneal lavage-drainage. Per-operative blood samples revealed type 6 Pseudomonas aeruginosa. Despite adapted parenteral antibiotics, fever persisted at 39 degrees C and intense jaundice was observed. A second laparoscopy 14 days later showed inflammatory narrowing of the main bile duct which was drained into a small bowel loop. Eight days later computed tomography revealed multiple abscess in the liver. Transparietal cholangiography was performed and showed that the contrast medium entered the abscesses via the biliary canals. The state of sepsis persisted, jaundice worsened and hepatic encephalopathy developed with obnubilation and flapping tremor. After 1 month of general antibiotherapy, no improvement was seen on computed tomography images and needle biopsy of an abscess led to the identification of resistant type 6 P. aeruginosa. Antibiotics were adapted and administered iv with no clinical improvement. Selective catheterism of the hepatic artery via the femoral access was performed to allow intra-hepatic antibiotic delivery. Three weeks later clinical situation remained unchanged when acute respiratory distress highly suggestive of pulmonary embolism led to death. Autopsy was not performed. In both of these rare cases of infectious complications due to P. aeruginosa after laparoscopic cholecystectomy, the source of contamination remained unknown. Nosocomial infection was suspected.

Anti-Bacterial Agents↗
PubMed1994

[Rhabdomyolysis in community-acquired pneumonia].

Several cases of rhabdomyolysis associated with pneumococcal pneumonia have been recently reported. However their significance have been poorly investigated. In this retrospective study, we have compared the patients admitted in ICU for acute community-acquired pneumonia with or without rhabdomyolysis (group A: CPK > or = 1,000 Ul/l and group B: CPK < 1,000 Ul/l). Among the 41 patients of the study, 12 (29%) belonged to the group A (CPK = 1,852 +/- 535 Ul/l) and 29 (71%) to group B (CPK = 190 +/- 35 Ul/l). Neither the initial severity, nor renal impairment were different in the two groups. However the mortality was significantly higher in the group A (4/12) than in group B (2/29) (P < 0.05). In this study, pneumonia is frequently associated with rhabdomyolysis, without etiologic significance. In patients with pneumonia, rhabdomyolysis seems to be a bad prognostic indice unrelated with renal impairment.

Adult↗
PubMed1994

[Vitelline tumor: a rare tumor of the mediastinum].

A young patient presented with a rare tumour of the mediastinum. The first sign was liquid effusion in the right hemithorax. A major rise in alpha-foeto-protein level to 34,000 ng/ml rapidly led to diagnosis. Histological confirmation was obtained on a surgical biopsy specimen of the lung. Management included primary polychemotherapy followed by complete surgical exeresis. A second post-operative cycle of chemotherapy was given but only led to temporary normalization of alpha-foeto-protein levels and intensive chemotherapy followed by autograft to peripheral stem cells was performed. The vitellin tumour is a primary germ cell tumour usually observed in young men. It originates in extraembryonary primary mesenchymal tissue. Like other germ cell tumours, the diagnosis should be entertained for all tumours of the anterior mediastinum. Tumour markers useful for diagnosis and prognosis are beta-HCG, AFP and CEA. Levels above 500 ng/ml confirm vitellin tumour. Chemotherapy should be instituted rapidly using a BEP protocol (bleomycine, etoposide, cisplatinium) or a PVB protocol (cisplatinium, vinblastin, bleomycine). Using these new drugs and current therapeutic protocols, the rate of complete remission has risen from 13% to 40%.

Adult↗
PubMed1994

[Sequencing of DNA by mechanical opening of the double helix: a theoretical evaluation].

We propose and evaluate a model experiment, in which the sequence of a DNA fragment is determined by mechanically opening the double helix in a controlled manner (e.g. pulling on the 3' end of one strand), and measuring the variation of the force exerted by the base pairs on a nanodynamometer (e.g. on a bead in an optical trap or a glass microneedle attached to the 5' end of the other strand). We show that the major limitation of the approach is the longitudinal elasticity of the already sequenced single strand sections, which soften the displacement-force function, and facilitate spontaneous thermal opening of the base pairs.

DNA↗
PubMed1993

Antagonism of metergoline on the diuretic effect of cyclazocine and U-50488 drugs with a kappa agonist activity.

In rats receiving a normal saline load of 2.5 ml/100 g, sc, (moderately hydrated rats), injections of the serotonin (5-HT) antagonist, metergoline (0.25-1-4 mg/kg), resulted in a dose-dependent decrease in the urine output induced by a dose of 8 mg/kg of cyclazocine (a benzomorphan derivative, mixed kappa and sigma agonist) at the 2-h time period. The antagonist effect of metergoline (1 mg/kg) on cyclazocine doses ranging from 0.25 to 8 mg/kg, was observed only at 2 mg/kg higher doses. Other 5-HT receptor blockers, methysergide, pizotifen, cyproheptadine, caused a significant degree of antagonism. In rats receiving a saline load and a water load of 5.5 ml/100 g, ip (hyperhydrated rats), metergoline (1 mg/kg) completely antagonized the diuretic effect of cyclazocine (8 mg/kg) at the 4-h and 5-h time periods. Similarly, metergoline (1 and 4 mg/kg) administered in moderately hydrated rats, markedly decreased at the 2-h time period, the urine output produced by 5 mg/kg of U-50488 (a non benzomorphan derivative, highly selective kappa agonist), and in hyperhydrated rats, completely suppressed, at the 4-h and 5-h time periods the drug-induced diuresis. Metergoline administered alone had no effect on urine output in moderately hydrated rats or in hyperhydrated rats. These results suggest the hypothesis that 5-HT may be involved in the complex mechanisms of kappa agonist-induced diuresis in rats.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1993

Triple combination penicillin-vancomycin-gentamicin for experimental endocarditis caused by a highly penicillin-and glycopeptide-resistant isolate of Enterococcus faecium.

A combination of low-dose penicillin (75,000 IU/kg twice daily [b.i.d.]) vancomycin (30 mg/kg b.i.d.) and gentamicin (6 mg/kg b.i.d.) has been shown to be as effective as a combination of high-dose penicillin (500,000 IU/kg b.i.d.) and gentamicin (6 mg/kg b.i.d.) in the treatment of rabbit endocarditis caused by an Enterococcus faecium strain moderately resistant to beta-lactams and highly resistant to glycopeptides. The same regimens were evaluated against an E. faecium strain highly resistant to both penicillin (MIC, 128 micrograms/mL) and vancomycin (MIC, 512 micrograms/mL). High doses of penicillin-gentamicin and vancomycin-gentamicin had no effect in in vitro killing-curve studies or in rabbits after treatment for 5 days. High doses of penicillin-vancomycin were only bacteriostatic in killing curves and provided a small reduction in the bacterial titers of the vegetations. In contrast, high-dose penicillin-vancomycin-gentamicin was bactericidal in vitro and highly effective in treating rabbits. However, the emergence of a bacterial subpopulation resistant to the synergistic effect of penicillin and vancomycin could reduce the clinical utility of this combination.

Animals↗
PubMed1992

A high degree of macronuclear chromosome polymorphism is generated by variable DNA rearrangements in Paramecium primaurelia during macronuclear differentiation.

DNA rearrangements in Paramecium lead to the formation of macronuclear chromosomes, the sizes of which range from 50 and 800 kb (1 kb is 10(3) base-pairs). This process does not appear to be a simple size reduction of the micronuclear chromosomes by specific and reproducible DNA sequence elimination and chromosomal breakage followed by chromosomal amplification. On the contrary, this process generates a variety of different, but sequence-related, macronuclear chromosomes from a unique set of micronuclear chromosomes. This paper describes an attempt to understand the nature of the diversity of the macronuclear chromosomes and the mechanisms of their production. The structure of three macronuclear chromosomes, 480, 250 and 230 kb in size, have been determined utilizing chromosome-jumping and YAC-cloning techniques. The two smallest chromosomes correspond roughly to the two halves of the longest chromosome. The main contribution to the diversity arises from the chromosomal ends and is due to variable positions of the telomere addition sites and/or to variable rearrangements of DNA sequences. The 480 kb chromosome contains a region of variable length, which is likely to be due to a variable deletion, located at the position of telomerization seen in the two small chromosomes. A model of chromosomal breakage is proposed to rationalize this result where micronuclear DNA is first amplified, broken and degraded to various extent from the newly formed ends, which subsequently are either telomerized or religated. Potential implications of these processes for gene expression is discussed. Known phenotypes that have a macronuclear determinism could be explained by this type of process.

Animals↗
PubMed1992

The differential expression of the G surface antigen alleles in Paramecium primaurelia heterozygous cells correlates to macronuclear DNA rearrangement.

The Paramecium primaurelia cell surface is covered with a high molecular weight protein called the surface antigen. Several genes encode alternative surface antigens, but only one is expressed at a time. In addition, each of these genes shows a high degree of allelic polymorphism. Paramecium primaurelia strains 156 and 168 have different alleles of the G antigen gene whose respective antigens can be distinguished in vivo using specific antibodies. An interallelic exclusion phenomenon has been previously described: 94% of the 156/168 heterozygotes express only the 156 allele of the G gene; 6% express both the 156 and the 168 alleles. The phenotype of the heterozygotes is determined at the time of macronuclear differentiation. We have investigated the molecular basis for the different heterozygous phenotypes. Both mRNAs are always produced, and the 156 mRNA is always more abundant than the 168 mRNA. The relative amounts of these messages, however, vary greatly between different heterozygotes and parallel their phenotype. Pushing the analysis further, we show that the copy number of each allele in the macronucleus correlates with the relative amounts of the mRNAs. However, allelic dosage alone is not sufficient to explain the variations of the mRNA ratio. The G antigen gene is located near a telomere in the macronucleus. We show that the distance between the 156G gene and the telomere is different in homozygotes and heterozygotes. It also varies among heterozygotes and is correlated with the mRNA ratio. Thus, we have identified two different parameters, both linked to the genome rearrangements occurring during macronuclear differentiation, that correlate with the relative expression of the two alleles. Two hypotheses concerning the influence of the telomere position on the expression of the gene are discussed.

Alleles↗
PubMed1992

Short-term treatment of urinary tract infections: the French concept.

The indications for short-term treatment to cure urinary tract infections (UTIs) have been recently clarified in France by a "Consensus Conference". Short-term treatment essentially concerns young, non-pregnant women with symptomatic uncomplicated lower UTI of less than three days duration, with no other underlying severe illness or previous uro-nephrological history, and who accept the idea of clinical and possibly bacteriological control after treatment. Only antibiotics with prolonged urinary excretion are recommended, i.e. co-trimoxazole, fluoroquinolones or fosfomycin-trometamol. In pregnancy, in children, or in the elderly, indications for short-term treatment still remain controversial. As compared with conventional therapeutic strategies using urine cultures, the use of test strips for nitrite and leukocyte esterase for deciding on treatment and assessing its efficacy should allow considerable financial savings.

Anti-Infective Agents, Urinary↗
PubMed1992

Daptomycin or teicoplanin in combination with gentamicin for treatment of experimental endocarditis due to a highly glycopeptide-resistant isolate of Enterococcus faecium.

Using an experimental endocarditis model, we studied the activity of daptomycin used alone or in combination with gentamicin against an Enterococcus faecium strain that was highly resistant to glycopeptides and susceptible to gentamicin. In vitro, the MIC of daptomycin was 1 micrograms/ml. In vivo, daptomycin appeared to be effective only when it was used in a high-dose regimen, i.e., 12 mg/kg of body weight every 8 h (-2.5 log10 CFU/g versus controls; P < 0.05), particularly when it was combined with gentamicin (-5.0 log10 CFU/g versus controls; P < 0.01). Since the distribution of daptomycin into cardiac vegetations, as evaluated by autoradiography, appeared to be homogeneous, the poor in vivo activity of daptomycin was considered to be related to its high degree of protein binding, as suggested by killing curves studies. Since the MIC of teicoplanin for the vancomycin-resistant E. faecium strain used in the study was only 64 micrograms/ml and since an in vitro synergy between teicoplanin at high dose and gentamicin was observed, a high-dose regimen of teicoplanin, i.e., 40 mg/kg every 12 h, was also assessed in vivo. This treatment provided marginal activity only when it was combined with gentamicin (-2.3 log10 CFU/g versus controls; P < 0.05). These results suggest that the levels of daptomycin or teicoplanin in serum required to cure experimental endocarditis caused by a highly glycopeptide-resistant strain of E. faecium would not be achievable in humans.

Animals↗
PubMed1992

[Inflammatory polyp: a rare benign endobronchial tumor].

We report a case of inflammatory polyp in a male patient, which was totally obstructing the left main bronchus but could be removed by simple endoscopic traction. The polyp was responsible for an absence of left lung ventilation which in turn produced by reflex an absence of left lung perfusion completely reversible after removal of the polyp. Inflammatory polyp is a rare benign tumour. Its physiopathology is controverted, but it seems to result from local irritation of the bronchial mucosa. Bronchial endoscopy is the essential examination which in most cases make it possible to diagnose and treat the tumour.

Adult↗
PubMed1991

Triple-combination penicillin-vancomycin-gentamicin for experimental endocarditis caused by a moderately penicillin- and highly glycopeptide-resistant isolate of Enterococcus faecium.

An in vitro bacteriostatic synergy between beta-lactam and glycopeptide antibiotics has been recently described against isolates of Enterococcus faecium moderately resistant to penicillin and highly resistant to vancomycin. The relevance of this synergy in a rabbit endocarditis model was evaluated. Penicillin was tested at low- (LoD) and high-dose (HiD) regimens, alone or combined with vancomycin and/or gentamicin. Compared with controls, after a 5-day treatment: LoD penicillin, vancomycin, gentamicin, LoD penicillin plus gentamicin or vancomycin, and vancomycin-gentamicin were not effective; LoD penicillin-vancomycin caused a small reduction of bacterial titers in vegetations that was strongly enhanced by adding gentamicin; HiD penicillin-gentamicin, the most effective regimen, was not significantly better than LoD penicillin-vancomycin-gentamicin. These results suggest that the relative in vivo inefficacy of penicillin-vancomycin might be related to the fact that this combination was poorly bactericidal, and the triple combination of LoD penicillin-vancomycin-gentamicin or the combination of HiD penicillin-gentamicin should be considered in the treatment of serious infections due to beta-lactam- and glycopeptide-resistant enterococci.

Animals↗