Structural requirements of sterols for myelin tube formation with sodium oleate.

Cholesterol crystals treated with an aqueous solution of sodium oleate give rise to cylindrical lamellar associations which appear under the microscope as rapidly growing tubes. Myelin forms are also obtained with other membrane sterols (desmosterol, cholestanol, 7-dehydrocholesterol) but not with lanosterol, a metabolic precursor of cholesterol, nor with the catabolic products of cholesterol (coprosterol, cholecalciferol, pregnenolone). The structural requirements for obtaining myelin tubes from sterols and sodium oleate closely agree with the results obtained by studying sterol-lecithin associations using other experimental techniques (unimolecular films at the air/water interface and permeability of liposomes), association of sterols with an erythrocyte protein and cholesterol liquid crystals.

Identification of a Bombyx collagenous protein with multiple short domains of Gly-Xaa-Yaa repeats: cDNA characterization and regulation of expression.

Using a differential screening strategy, a 2 kb cDNA was isolated from a differentiating Bombyx mori imaginal wing discs library. The available reading frame of 1710 bp specifies a conceptual protein with two distinct regions: a 395 amino acid region corresponding to 105 repetitions of the Gly-Xaa-Yaa triple-helical forming unit arranged in 9 domains of 12-54 residues interspaced by short interruptions of 3-17 residues and a C-terminal domain of 175 amino acids devoided of triplets. These characteristics suggest that the encoded protein is a new member of the collagen superfamily, the first one characterized in Bombyx. Northern blots reveal a unique 7.4 kb mRNA in imaginal wing discs, epidermis and brain. In wing discs, the 7.4 kb transcripts accumulate during the last larval moult and the spinning stage. In vitro studies reveal that this accumulation is dose dependent and detectable within 1 h in response to 20-hydroxyecdysone which acts without de novo protein synthesis. A model of regulation of transcript accumulation with regards to the hormonal level is proposed.

INFLUENCE DU JEÛNE AU NIVEAU ORGANIQUE CHEZ PHILOSAMIA CYNTHIA WALKERI. POIDS ET INCORPORATION A LONG TERME D'ACIDES AMINÉS.

The weight of organs and course of long term incorporation of amino acids into proteins are followed during a 48 hr starvation in Philosamia cynthia walkeri. In each organ, both parameters follow synchroneous evolutions: decrease of weight and amount of radio-active proteins since the beginning of starvation in the fat body; rapid increase during the first 6-12 hr in the intestine and integument, then a decrease. In hemolymph, the amount of radio-active proteins increases during 6hr and is stable thereafter. In the same time, the acid-soluble radio-activity is more depressed in the fat body than in hemolymph, and less in the integument and silkgland than in hemolymph. These results are discussed in relation with the influence of the fat body on growth and metabolism regulations during starvation. Two main hypothesis are suggested: intense exportation of amino acids from fat body to hemolymph in order to maintain a high level of material in the internal milieu; continuation of the growth of organs during the first hrs of starvation partly supported by the fat body.

PROTEIN SYNTHESIS IN THE FAT BODY OF THE FIFTH LARVAL INSTAR PHILOSAMIA CYNTHIA LARVAE-RELATION TO TWO FEEDING PERIODS.

In order to investigate the determinism of the metabolic variations associated with developmental change, protein synthesis was measured in vivo, in the fat body of Philosamia cynthia. During the fifth larval instar two periods, the necessary feeding period and the facultative feeding period, which constitute decisive developmental periods of the insect were xamined. eAfter incorporation of [3 H]-glycine protein synthesis was estimated by a calculation which takes account of the dilution of the radioactive amino acids in the free amino acid pool. During the necessary feeding period (from ecdysis to day 4) the protein synthesis increased steadily whereas during the facultative feeding period (from day 4 to onset of spinning) the protein synthetic level decreased. Some preliminary hypotheses are suggested for the mechanism responsible for protein synthesis variations during a larval instar.

Evaluation of the BDProbeTec ET DTB assay(1) for direct detection of Mycobacterium tuberculosis complex from clinical samples.

The purpose of this study was to evaluate the ability of BDProbeTec ET DTB system to detect Mycobacterium tuberculosis complex directly from clinical specimens. A total of 628 specimens (553 respiratory and 75 non respiratory specimens) were collected from 478 patients. These samples were tested with the BDProbeTec ET DTB assay and results were compared with acid fast microscopy and culture. Sixty eight out of 77 culture positive M. tuberculosis complex samples were detected with overall sensitivity and specificity of 89.5% and 98.2% respectively. Overall sensitivity was 100% in smear positive samples and 79% in smear negative samples. After resolution of discrepant results, sensitivity and specificity for respiratory samples were 91.6% and 98.7% respectively. BDProbeTec ET DTB assay demonstrated to be a rapid, sensitive and specific method for detection of M. tuberculosis complex.

[Colorimetric determination of cholesterol in biological fluids using 2,3-naphthalenedicarboxaldehyde (author's transl)]. / Dosage colorimétrique du cholestérol dans les milieux biologiques par le naphtalène dicarboxaldéhyde-2,3.

The authors describe a new method of cholesterol determination, using the intense blue color given by interaction with 2,3-naphthalenedicarboxaldehyde in a sulphoacetic medium. The degree of precision of the method, as well as its reproducibility are discussed; a good correlation of the new method with two classical techniques, the colorimetric method of Liebermann and the enzymatic method, is observed. The high sensitivity and the specificity of the colour reaction allow the choice of the method for a direct determination of serum cholesterol using a 10 microliter sample.

[Randomized prospective study of ceftazidime versus a cefotaxime-tobramycin combination in acute leukemia in therapeutic aplasia]. / Etude prospective randomisée, de la ceftazidime versus l'association céfotaxime-tobramycine, dans les leucémies aiguës en aplasie thérapeutique.

In a prospective study, 157 patients with prolonged aplasia (PMN less than 500/mm3 during more than 21 days), hospitalized in a protected environment unit, were randomly assigned to receive ceftazidime alone or cefotaxime + tobramycin for initial febrile episodes. Age, sex, underlying diseases, duration of neutropenia, digestive decontamination regimen, clinical and microbiological characteristics of infections were similar in the two groups. Patients were evaluated for their initial response to antibiotics (defervescence in 48 hours, maintained 7 days) and long term response (prevention of another infection during aplasia). The overall initial response to ceftazidime was 48/71 (68 per cent) and to cefotaxime + tobramycin 55/86 (64 per cent). The long term response to ceftazidime was 33/71 (46.5 per cent) and to cefotaxime + tobramycin 31/86 (36 per cent). In conclusion, ceftazidime alone was as effective as cefotaxime + tobramycin in the first line treatment of febrile episodes in neutropenic patients.

[The functioning of the mitochondrial system and respiration at the 5th larval instar in Pieris brassicae (Lepidoptera)]. / Le fonctionnement du système mitochondrial et la respiration au 5e stade larvaire chez Pieris brassicae (Lépidoptère).

The profiles of respiratory rate, total proteins, mitochondrial proteins and mitochondrial activity have been described during the fifth instar of Pieris brassicae reared either under long-day or short-day photoperiod. There was no fundamental difference per unit of live weight between the long-day and short-day larvae. The biochemical characteristics of the larval mitochondria have been described, and the mitochondria were shown to oxidize succinate better than alpha-glycerophosphate. Two periods during the fifth instar were related to mitochondrial activity. During the first one, this specific activity was high during 50 to 60 p. 100 of the instar; it then decreased. This alteration was superimposed on changes in the hormonal balance. It is shown that the respiratory rate was not only a passive response to the energy demand, and that specific mitochondrial activity must be considered as a parameter of the development program.

[Interference of hydrazine derivatives with the tyrosinase-tyrosine reaction]. / Interférence de dérivés de l'hydrazine zur la réaction tyrosinase-tyrosine.

A comparative study of the tyrosinase-tyrosine reaction, using both oxygen-consumption determination and spectrophotometric methods, shows that hydrazine derivatives inhibit melaninogenesis at different steps.

[Effect of various technics in the determination of sensitivity of Pseudomonas aeruginosa to imipenem]. / Influence de différents facteurs techniques dans la détermination de la sensibilité de Pseudomonas aeruginosa à l'imipénème.

The in vitro activity of imipenem was determined against 115 isolates of Pseudomonas aeruginosa. The susceptibility was compared according to two technics: disk diffusion method and minimal inhibitory concentration determinations (MIC), this, with three different Mueller Hinton agar (Diagnostics Pasteur, bioMérieux, Amor Equipement Scientifique) and two inocula. There is not inoculum effect. On the contrary, except for extreme values, there is discrepancies in the activity according to the medium. The correlation between zone diameters and MIC values is less good when Mérieux and AES Mueller Hinton agar were used.

[In vitro effect of combinations of daunorubicin and antibiotics against various bacterial strains]. / Activité in vitro des associations daunorubicine et antibiotiques sur diverses espèces bactériennes.

The associations of daunorubicin with various antibiotics were studied by the broth dilution method ("checkboard" technic). The FIC Index were calculated to evaluate the effect of the various combinations. Antibiotics tested were chosen according to the bacterial species: vancomycin, cefotaxime, oxacillin, tobramycin, rifampicin against 15 isolates of Staphylococcus, ampicillin, piperacillin, vancomycin, rifampicin against 10 isolates of enterococci, piperacillin, ofloxacin, tobramycin against 5 E. coli strains. No antagonistic effect was observed whatever the antibiotic or bacterial strain. Against enterococci, all combinations showed a synergistic or additive effect, the most pronounced effect being demonstrated with rifampicin (FIC Index value around 0.3). Among the combinations tested against Staphylococcus, the combination daunorubicin + tobramycin demonstrated synergy against all but 1 strain tested, the combinations including oxacillin, cefotaxime or rifampicin showed a synergistic or additive effect, combinations including vancomycin showed addition or no drug interaction. Antibiotics tested against E. coli gave a synergistic combined drug effect in some cases, more often an additive effect, some time no interaction, depending on the strain.

[Evolution of bacterial resistance to five aminoglycosides. A study of 3,354 strains isolated in a hospital milieu]. / Evolution de la résistance bactérienne à cinq aminosides. Etude portant sur 3,354 souches isolées en milieu hospitalier.

The authors studied the susceptibility to 5 aminoglycosides (amikacin, dibekacin, gentamicin, netilmicin and tobramycin) of 3,354 strains isolated at the Centre Hospitalier Sud in Bordeaux during 1987. The results are compared to those obtained in 1984 on 2,818 strains. Amikacin remains the most active aminoside against the Enterobacteriaceae and Acinetobacter; against Pseudomonas, tobramycin has become the best one at that time, as well as netilmicin against Staphylococcus aureus. Evolution: no significative increase of Enterobacteriaceae resistance to aminoglycosides was observed during the last 3 years except for Providencia and Serratia. For Acinetobacter and Pseudomonas, percentage of resistant strains is respectively two-fold and three-fold higher. Although resistance increased in that species, netilmicin and amikacin showed a still good activity against Staphylococcus aureus.

In vitro activity of four fluoroquinolones against eighty-six isolates of mycobacteria.

The in vitro activity of pefloxacin, norfloxacin, ofloxacin and ciprofloxacin against 86 strains of mycobacteria was evaluated by broth dilution. While Mycobacterium avium, Mycobacterium scrofulaceum and Mycobacterium chelonae were resistant to all four antibacterials, the susceptibility of the other species, Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium xenopi and Mycobacterium fortuitum, depended on the antibiotic. Ofloxacin and ciprofloxacin (MIC90: 0.5 - 2 mg/l) were more active than pefloxacin and norfloxacin (MIC90: 2 - 16 mg/l).

Analysis of cellular fatty acids and proteins by capillary gas chromatography and sodium dodecyl sulphate polyacrylamide gel electrophoresis to differentiate Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium scrofulaceum (MAIS) complex species.

Infections due to atypical mycobacteria have increased during the past 30 years. Species of Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium scrofulaceum are among the most common non-tuberculous mycobacteria isolated from patients with AIDS or immunosuppressed. These three organisms are taxonomically closely related and identification, according to cultural characteristics and biochemical tests, is not always evident, so some of these related strains are grouped in a "MAIS" complex. Analysis of cellular constituents is an aid to identification. Gas chromatography was used to study mycolic acids and a secondary alcohol was found which is a discriminating constituent between M. scrofulaceum and the other two species. The lipidic analysis was not able to separate M. avium and M. intracellulare, so cell proteins were considered. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of proteins reflects genetic relatedness between strains; the different patterns obtained from these three species are described and it is shown that this method is very useful in classification and epidemiology.

[In vitro sensitivity of Mycobacterium avium and Mycobacterium xenopi to erythromycin, roxithromycin and doxycycline]. / Sensibilité in vitro de Mycobacterium avium et Mycobacterium xenopi a l'érythromycine, roxithromycine et doxycycline.

The comparative in vitro activity of erythromycin, roxithromycin and doxycycline against 20 isolates of M. avium and 20 M. xenopi was evaluated by two technics: a standard macrobroth dilution (7H9) and the 1% standard proportion method on lowenstein medium. M. avium was highly and uniformly resistant to doxycycline (MIC 50: 64 mg/l). For macrolides some strains were moderately susceptible to roxithromycin and at a lower level to erythromycin the MIC 50 and MIC 90 were respectively 8 and 16 mg/l for roxithromycin, 16 and 64 mg/l for erythromycin. Both macrolides were active against most of the strains of M. xenopi MIC 90 and MBC 90 were respectively 0.25 and 1 mg/l for roxithromycin, 0.5 and 2 mg/l for erythromycin. Doxycycline was less active inhibiting 90% of strains only at 16 mg/l.

[In vitro activity of pristinamycin against Streptococcus pneumoniae]. / Activité in vitro de la pristinamycine sur Streptococcus pneumoniae.

The activity of the pristinamycin was investigated using disk diffusion agar or ATB PNEUMO system and MIC determination using reference liquid medium method (NCCLS) on 749 S. pneumoniae strains isolated in Aquitaine in 1999. We have realized the killing curves against 10 isolates selected from erythromycin-susceptible and resistant S. pneumoniae strains. All the strains tested by ATB PNEUMO system were susceptible to pristinamycin, using disk diffusion agar, 6.8% of strains were intermediate or resistant. However the MIC's of pristinamycin determined by liquid dilution method against these strains were < 1 mg/L. These data suggest that the zone of inhibition around the disk was not correlated with MIC for erythromycin pneumococci and MIC testing must be performed. The results of killing curves showed a very good and rapid bactericidal activity of pristinamycin within two hours for concentration equal to 4 x MIC and four hours for 2 x MIC.

[Alpha-hydrazinophloretic acid, competitive inhibitor of fungal tyrosinase]. / L'acide alpha-hydrazinophlorétique, inhibiteur compétitif de la tyrosinase fongique.

alpha-Hydrazinophloretic acid, the hydrazino analogue of tyrosine, was shown to behave as a competitive inhibitor of tyrosinase. Some closely related compounds, especially the hydrazino analogue of phenylalanine as well as other hydrazine derivatives, will also inhibit the enzyme, but in these cases, the inhibition observed belonged to the non-competitive type.

In vitro activities of vancomycin and teicoplanin against coagulase-negative staphylococci isolated from neutropenic patients.

This study reports the in vitro activities of vancomycin and teicoplanin against 185 coagulase-negative staphylococcal strains isolated from 80 neutropenic patients who received different antibiotic treatments. All strains were susceptible to vancomycin: MICs for 50 and 90% of strains tested were 2 and 4 mg/liter, respectively. Teicoplanin was less active, and MICs displayed a wider range. For only teicoplanin was there a correlation between resistance and previous treatment. At the 4- and 32-mg/liter breakpoint levels, only 20% of the strains isolated from patients without glycopeptide treatment were intermediate or resistant, whereas 49.2% of the strains from patients who had received vancomycin or teicoplanin or both were intermediate or resistant.

[Bacteriostatic activity of azlocillin, gentamycin, amikacin singly or in combination on 200 strains of Pseudomonas aeruginosa]. / Activité bactériostatique de l'azlocilline, gentamicine, amikacine seuls et en association sur 200 souches de Pseudomonas aeruginosa.

In vitro activity of azlocillin, gentamicin, and amikacin, alone or in combination was evaluated against 200 clinical isolates of Pseudomonas aeruginosa. The minimum inhibitory concentrations (MICs) were determined by a standard technique. For the evaluation of synergistic activities, one antibiotic was added in a concentration equivalent to one-fourth its MIC to increasing concentrations of the other antibiotic. The MIC for 50% of the strains was 3.25 micrograms/ml for gentamicin, 3 micrograms/ml for amikacin and 7 micrograms/ml for azlocillin. No significant difference could be seen between the two combinations, the percentage of synergy was 37% for azlocillin-gentamicin and 36% for azlocillin-amikacin. No antagonism was observed.