Effect of iron and phagocytosis on murine macrophage activation in vitro.

Iron-exposed murine macrophages have a modified bactericidal activity as shown by previous observations. In order to assess the role of iron in macrophage activation, as measured by free radical production and by intracellular bacterial killing, murine peritoneal macrophages were cultivated in the presence of various sources of iron, human iron-saturated transferrin and ammonium ferric citrate, or iron chelators, Desferal, and human Apo-transferrin, and were infected with an enteropathogenic strain of E. coli. The release of nitrite (NO2-), and the production of superoxide anion (O2-) and hydrogen peroxide (H2O2) by the phagocytes were measured and compared to the production by uninfected macrophages. The synergistic action with murine r.IFN-gamma was also studied in the radical production reaction and for the bactericidal activity of macrophages. Our results show that in vitro phagocytosis of E. coli induced elevated production of NO2- and H2O2 by macrophages, and that oxygen derivatives were released independently of the presence of added iron or chelator. Despite a phagocytosis-related enhancement of NO2- release, reactive nitrogen intermediates (RNI) are not directly involved in the bactericidal mechanism, as revealed by increased intracellular killing owing to RNI inhibitors. Moreover, bacterial killing may depend on oxygen derivatives, as suggested by the effect of the antioxidant sodium ascorbate leading to both a diminished H2O2 production and a decreased bactericidal activity of macrophages.

[Biocontamination, European standardization and pharmaceutical industry]. / Biocontamination, normalisation européenne et industrie pharmaceutique.

The coming to light of new concepts in environmental microbiology, particularly the notions of bacterial adhesion and of biofilm or of cells in starvation, conducted to an evolution of the standardization of the controlled contamination area. It is necessary to match to the biocontamination of hazard area the principles governing the quality insurance used in alimentary industry named HACCP (hazard analysis of control critical point). This method will have to be applied wilfully to all the fields where a patient or a product risk a biocontamination.

[Biological safety in the laboratory. Biological risk, standardization and practice]. / Biosécurité au laboratoire. Risque biologique, normalisation et pratique.

Working with pathogens or genetically engineered micro-organisms is a potential hazard for scientists, health care workers, employees of pharmaceutical industry, and also for the environment. Carelessness, poor technique in the handling of infectious materials, needle sting or infectious aerosol exposure are the cause of laboratory acquired infection. Biosafety, corollary of biocontamination, is based on the combination of good microbiological techniques, facility design of the laboratory and safety equipment. So, four biosafety levels are appropriate for the operations performed and the hazard posed by the infectious agents.

Relationship between free amoeba and Legionella: studies in vitro and in vivo.

In 1980, Robowtham demonstrated that Legionella multiplies in free amoeba cytoplasm and hypothesized that the amoeba could act as a reservoir of virulent bacteria. In this paper we report various aspects of the relationship between amoeba and Legionella. A liquid medium co-culture method was applied to Acanthamoeba sp. and Legionella pneumophila serogroup 1. Within 4 days, Legionella growth increased by 2 log s CFU/ml. Using a direct immunofluorescence assay and electron microscopy, Legionella was shown to grow abundantly inside phagosomes, and bacteria and/or antigen were present on the cytoplasmic membrane of the amoeba. These aspects are very similar to those observed with Legionella-infected alveolar macrophages. The morphology and structure of Legionella cells were modified after 20 days of co-culture: - viable bacteria showed large fatty cytoplasmic inclusions, - gas liquid chromatography analysis demonstrated a decrease in the i16:0 fatty acid ratio. Cystic forms of amoeba were abundant but none contained viable Legionella. In an in-vivo study using a guinea-pig aerosol infection model, we compared the virulence of Legionella in co-culture with Legionella grown on charcoal dialysed yeast extract (CDYE) agar medium. The Legionella obtained by co-culture had an LD 50 (50% lethal dose) similar to that obtained for those grown on CDYE, showing that bacterial virulence is preserved in the cellular model.

Comparative efficacy of five antibiotics on experimental airborne legionellosis in guinea-pigs.

The efficacy of preventive and curative treatment of experimental airborne legionellosis in guinea-pigs was studied for erythromycin, rifampicin, minocycline, doxycycline and pefloxacin. The aerosol was produced from a strain of Legionella pneumophila serogroup 1 and dispersed in a chamber maintained below atmospheric pressure. Guinea-pigs were exposed for 30 min to 1 or 10 LD50 (10(3) or 10(4) viable inhaled organisms). Treatment was preventive or curative. Antibiotic concentrations in lungs and serum were evaluated during treatment. The action of the antibiotics on guinea-pigs infected by 1 LD50 resulted in 100% survival. For the 10 LD50 infection, pefloxacin, minocycline and erythromycin were more active (with 87.5% survivors) than doxycycline (75%) and rifampicin (62.5%). Preventive treatment with pefloxacin or doxycycline gave 100% protection, compared with 87.5% for rifampicin, 50% for erythromycin and 37.5% for minocycline. In this study, treatment of experimental legionellosis was improved, compared with previous publications, by early administration of antibiotics and increased dosage and duration.

Efficacy of spiramycin on experimental airborne legionellosis in guinea pigs.

The effect of preventive and curative spiramycin therapy was studied in guinea pigs infected by aerosol with the experimental model previously tested. The infectious aerosol was obtained from a virulent strain of Legionella pneumophila (Philadelphia ATCC 33 152). Male guinea pigs (Dunkin-Hartley) weighing 250-300 g were exposed for 30 min to an aerosol of 1 or 10 LD50 (10(3) or 10(4) viable inhaled organisms). Spiramycin was administered intraperitoneally (150 mg/kg/day) 18 h after infection for five days for curative therapy; for preventive therapy it was administered on the day before and on the day of aerosol administration (10 LD50). The animals were observed during seven days for weight and temperature and 28 days for survival; bacterial (lungs, spleen) and serological tests were performed. Spiramycin levels (lungs, serum) were evaluated during treatment by a microbiological method. The survival rate in the treated guinea pigs after inhalation of 1 LD50 was 100%. For the 10 LD50 aerosol, curative and preventive therapy gave a survival rate of 87.5%; these results are significant when compared with results of non-treated animals, P less than 0.05. Spiramycin merits further study in experimental and human legionellosis.

[Doxycycline treatment of experimental legionellosis in guinea pigs infected by aerosol]. / Traitement par la doxycycline de la légionellose expérimentale du cobaye infecté par aérosol.

The efficacy of curative and preventive treatment by doxycyclin was studied with the same experimental model as during the study of erythromycin [14]. The infectious aerosol was done with a strain of Legionella pneumophila serogroup 1, Philadelphia (ATCC 33152). Male albinos Dunkin-Hartley guinea-pigs were exposed for 30 min to an aerosol dose of 1, 10 or 100 LD 50 (10(3), 10(4) or 10(5) viable organisms). After preliminary assays to find out the efficient posology, doxycyclin was administered intraperitoneally (IP) 18 h after the infection at a dosage of 60 mg/kg/day for 5 days in the animals infected with 1 LD 50, and 75 mg/kg/day in the animals with 10 and 100 LD 50. The preventive treatment (75 mg/kg/day) administered one day before and the day of the infection was tested with animals infected with 10 LD 50. The guinea-pigs were observed 8 days (weight, rectal temperature) and watched over 3 weeks after the end of treatment; serological and bacteriological tests (cardiac blood, lungs, spleen) were performed in every animal; doxycyclin assays (serum, lungs) during treatment were performed by high performance liquid chromatography (HPLC). The treatment of guinea-pigs infected by 1, 10 and 100 LD 50 gave a survival rate of 100%, 75% and 50% respectively. On the other hand the animals which received preventive treatment were all survivors. Seroconversions with antibody titres from 64 to 512 were observed for all the survivors. Bacteriological tests were all negative. The mean doxycyclin concentrations in serum (microgram/ml) and lung (microgram/g) were 1.66 and 11.42 after 24 h of treatment and 5.71 and 18.93 after 7 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased resistance to Salmonella infection of hypoferremic mice fed a low-protein diet.

BALB/c and CBA/CA mice fed a protein-deficient diet developed a plasma hypoferremia corresponding to a 30 percent lowering of serum iron concentration. This hypoferremia persisted as long as the diet was maintained. Hypoferremic CBA/CA mice had increased resistance to Salmonella typhimurium C5 infection, as shown by the reduced lethal activity and the decreased growth of the bacteria in the spleen and in the peritoneal exudate of the deficient animals. This induced resistance was abolished after injection of iron or Desferal into the restricted animals. Such resistance was not observed with BALB/c mice fed a protein-deficient diet, in spite of the plasma hypoferremia. The growth of S. typhimurium C5 in the spleen and in the peritoneal exudate of these animals did not differ from the growth observed in control animals fed a protein-sufficient diet. This study suggests that hypoferremia induced by a protein-deficient diet is probably involved in the enhancement of resistance of CBA/CA mice to Salmonella infection, and that the phenomenon is host-strain dependent.

[Role of iron and a siderophore in the development of bacterial infections in the mouse: the study of two bacteria and three routes of inoculation]. / Rôle du fer et d'un siderochrome dans le développement d'infections bactériennes chez la souris: étude de deux bactéries et de trois voies d'inoculation.

We have studied the influence of ferric iron and the influence of a siderophore on the lethal activity of two Bacteria injected in Mice intraperitoneally intravenously or orally. Iron and the siderophore significatively increase the lethal activity of an avirulent Bacteria, Enterobacter cloacae, injected intraperitoneally or intravenously. The virulence of a Bacteria pathogen for Mice, Salmonella typhimurium, is also increased when injected intraperitoneally. Therefore we have noted a decrease in virulence when this Bacteria was injected intravenously or orally in Mice treated with the siderophore.

[Microbiological contamination of enclosed air spaces. Origin, methods for studying]. / La contamination microbiologique des atmosphères closes. Origines, méthode d'études.

The authors make a bibliographical review of methods for studying the microbiological contamination of closed atmosphere. In a first part, they study the origins of bacterial emission (emissions from nose and pharynx, aerosolization by hospital hands manipulations, skin's emissions). In a second part, the study concern the measure of atmospheric contamination. The authors insist on the correlation may be existed between the counting of all dimensions particles and the bacteria's presence in air. They analyse in details the biological methods of measure (sedimentation, centrifugation, filtration impact) and suggest a room classification according to theirs biological contaminations.

Development of "sports anemia" in physically fit men after daily sustained submaximal exercise.

Hematological changes were studied in physically fit young soldiers who marched 35 km/d for 6 d, working at 35% of their Vo2 max. Four days of marching produced decreases in numbers of erythrocytes (RBC) and in hematocrit (Hct). This "sports anemia" persisted beyond day 6 into the post-march period and was accompanied by decreases in hemoglobin (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular volume (MCV). The latter decrease was attributed to a preferential destruction of large RBC. The post-march period was characterized by an early (2 d) recovery of RBC numbers, Hct, and MCV, and a persistent (greater than 4 d) decrease in Hb, MCH, and MCHC. This pattern, characteristic of hypochromic macrocystosis, possibly reflects a premature release of young RBC from the bone marrow. Clearly, "Sports anemia," previously reported to occur with intensive physical exercise, can also result from sustained and repetitive submaximal exercise.

[Enzymatic activity of peritoneal macrophages of Balb C mice after enteral or parenteral stimulation with bacterial extracts]. / Etude de l'activité enzymatique de macrophages péritonéaux de la souris Balb/C après stimulation par voie entérale ou parentérale à l'aide d'extraits bactériens.

A study of peritoneal macrophage activation has been conducted by simultaneous investigation in eleven enzymes in Balb/c Mice stimulated with bacterial extracts, by oral and parenteral route. The results showed important changes in Macrophage number and activity. On the other hand this activation depended upon the route of administration, antigen nature, and time interval between stimulation and peritoneal harvesting.

[Studies in the BALB/c mouse of the efficiency of spraying as compared to other inoculation ways for immunostimulant (author's transl)]. / Etude, chez la souris Balb/c, de l'efficacité de la voie aérosol comparativement à d'autres voies d'inoculation, dans le cas d'un immunostimulant.

The of efficiency of spraying as compared to intranasal and digestive ways was tested on Balb/c mouse by using on the one hand an immunostimulant product and on the other various types of test : Myxovirus influenzae by aerosol, Streptococcus pyogenes intranasally, Klebsiella pneumoniae intraperitoneally. Results showed that in the case of influenza virus the immunostimulant inhaled as liquid aerosol or powder aerosol, or deposited on the nasal mucosa was very active. When the test germ was Streptococcus and the contamination intra-nasal, only the homologous way was efficient. When the test germ was Klebsiella pneumonia all inoculation forms except powder aerosol were effective. The comparative study of aerosols granulometry helps grasping this phenomenon.

[Influence of environmental conditions on human hematologic constants]. / Influence des conditions d'environnement sur les constantes hématologiques humaines

A blood investigation was carried out on 3,030 volunteer blood donors and the results treated on a computer by multivariant analysis. The authors noted a depressor effect of the urban environment on the red and white cells, a rise in small lymphocytes and a reduction in monocytes in patients living in industrial areas. This stimulation of the lymphocyte system may be compared with the experimental results obtained by the same authors in animals.