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GC1 est une bacterie isolee de la Seine en 1991 et rattachee au genre Acinetobacter en raison de la sequence de son ARN 16S et de ses caracteres phenotypiques. L'etude de la sequence de la sous-unite B de son ADN gyrase (gyrB) la rattache au groupe genomique #19 defini recemment par Yamamoto, Bouvet et Harayama (1999). Sa capacite a degrader les alcanes de C10 a C40, a des temperatures variant de 4 a 35° C dans un environnement marin ou dulcaquicole la rend d'autant plus interessante a utiliser lors d'operations de biorestauration marine ou fluviale qu'elle resiste parfaitement au contact physique d'hydrocarbures toxiques comme le gasole ou le petrole brut grâce a une structure protectrice de surface originale.

La survie et la croissance de deux souches de Pseudomonas fluorescens L6.5 et L5.2 isolees de la Seine ont ete etudiees dans deux milieux oligotrophes. Le premier milieu consistait en eau pyrolysee a 650°C alors que le second etait du PBS (Phosphate Buffered Saline de Dulbecco) realise dans cette meme eau. La survie des souches resuspendues dans ces deux milieux a ete suivie pendant plus de 7 mois. Pour les deux souches, la survie dans l'eau pyrolysee a ete tres superieure a celle observee dans le PBS, mais la resistance de L6.5 est superieure a celle observee pour L5.2. En ce qui concerne leur croissance, les deux souches (L5.2 et L6.5) sont capables de croitre rapidement en milieu minimum, mais egalement de soutenir une croissance prolongee dans l'eau pyrolysee, meme en l'absence de lumiere (plus de 100 generations) et de CO 2 . L'effet modulateur d'ajouts specifiques (sources de C, N, P, S et Mg) a enfin ete etudie sur le taux de croissance de L6.5 en eau ultrapure. L'effet stimulant du phosphate est particulierement spectaculaire (doublement du nombre de generations) puisque l'effet maximum est deja atteint pour une concentration de 10 −7 M. Deux systemes de transport de phosphate ont pu etre mis en evidence sur cette souche, un systeme a faible affinite (K m apparent de 1 mM) et un systeme a haute affinite (K m apparent 0,8 μM. La concentration en COT de l'eau pyrolysee utiLisee etant inferieure a 50 μg/l, les souches de Pseudomonas fluorescens utilisees (L6.5 est L5.2) sont capables d'utiliser efficacement ce COT a des concentrations de l'ordre d'une dizaine de μg/l. Ces observations permettent de comprendre comment des souches de Pseudomonas fluorescens peuvent proliferer dans des reseaux d'eau pure comme ceux rencontres dans les centres d'hemodialyse et les laboratoires d'analyses

Un pilote a ete concu pour apprecier le comportement bacteriologique, microtoxicologique et physicochimique des materiaux en contact avec l'eau (tuyaux, joints, revetements). Ce pilote qui reproduit les conditions reelles d'exploitation des reseaux de distribution est un systeme dynamique ferme.Dans un premier temps, une etude de l'evolution dans l'eau d'une population bacterienne bien definie a ete entreprise sur quatre souches usuelles de l'eau. Elle a montre qu'apres une periode de croissance les bacteries atteignent un etat quasi-stationnaire, tres stable, qui permet d'observer les modifications dues aux tuyaux. Une etude systematique de tous les facteurs de variabilite des resultats (effet mecanique, force ionique, qualite de l'eau, nutriments) a abouti a la totale maitrise du systeme.Tous les types de materiaux peuvent ainsi etre testes dans tous les types d'eau et dans une large gamme de temperatures, aussi bien du point de vue microbiologique que microtoxicologique et physicochimique. Des resultats pratiques sont montres.

The search for risk factors for development of germ cell tumors (GCT) in children who lived in Mexico City (MC). A protective, observational, case-control study was conducted in children under 15 years of age resident in MC, insurer by the Mexican Institute of Social Security. The study population was selected between January 1st, 1990 and December 31st, 1994. Parents of the children were interviewed with a 230-items precoded questionnaire, validated previously with a pilot study. For analysis were obtained simple frequencies and odds ratios (OR) and 95% confidence interval (95%CI). There were 21 cases and 105 controls. The most significant risk factors were winter conception (OR = 7.6, 95% CI 1.5-39.3; P = 0.007); low parental education level (OR = 2.9, 95% CI 1.1-7.5; P = 0.026); and parental combined dust and electricity exposure before pregnancy (OR = 26, 95% CI 2.28-1291.86; P = 0.0007). during (OR8.58, 95% CI 0.89-106.55; P = 0.041) and after pregnancy (OR = 9.66, 95% CI 0.99-120.22; P = 0.027). There was a protective effect with repetitive infections during infancy. In conclusion, Winter conception is in accordance with infectious etiology theory of GCT development. The low parental education level and the combined exposure to dust and electricity are very important. The protective effect of repetitive infections and other factors make necessary more epidemiologic studies in this field.

A method is described for mutagenesis of Pseudomonas fluorescens strains by electroporation with the transposon delivery vector pUT/mini-Tn5 Km. The transposition process was shown to be optimal at 12.5 kV cm-1 for a pulse time (Bowen and Koslak, 1992) of about 4 ms. The Pseudomonas fluorescens L6.5 target strain exhibited maximal electrocompetence when harvested at the middle of the exponential growth phase. As many as 7.7 10(5) mutants per picomole of delivery vector (7.5 kb) could be obtained, and these kanamycin-resistant mutants were shown to have lost the pUT plasmid. By external calibration with plasmids of increasing size (from 11.5 to 60.1 kb), the efficiency of the transformation process was evaluated to be approximately 1.31 x 10(8) transformants per picomole of delivery vector. Efficiency of the transposition process was 0.58%. This rapid method was used to tag for the cloning three independent chromosomal loci responsible for the Alk+ phenotype of Pseudomonas fluorescens L6.5 strain.

Seventy seven cases with discharge before 12 hours post-partum and 240 cases with discharge after 24 or more hours after delivery, were evaluated at Hospital General de México, in an observational, prospective, cohort, study in low risk deliveries. Both groups were reviewed ten days after delivery. There were no different ratios for abnormal uterine hemorrhage, urinary tract infection or endometritis. Thrombophlebitis was more frequent in early discharge patients, both statistically and clinically significant (RR3.58, CI95% 1.48-8.67, P = 0.003). This finding is discussed, as well as measures to prevent it. It is concluded that early discharge programs in low risk conditions, are convenient.

At the Hospital de Ginecobstetricia del Centro Medico "La Raza", between october 1, 1990 to may 31, 1991, were attended 50 women with premature labor, with pregnancies of 30-36 week sold. They were given 100 mg of indomethacin, rectal, daily, in order to obtain arrest of the uterine activity. The mean doses given was 4 +/- 0.739. In 26 (52%) patients there were transient, fetal ductal constriction. In these patients there were high fetal heart rate variability during the ductal constriction time. No other fetal an neonatal effects were documented. It is recommended when indomethacin was given in premature labor treatment a fetal ecocardiogram and the fetal and neonatal study of the patients in research of cardiovascular side effects, included neonatal pulmonary hypertension syndrome.

La mesure de l'ancrage cellulaire a permis l'evaluation du relargage de toxiques par des materiaux utilises dans la distribution de l'eau. Elle est basee sur l'inhibition de l'ancrage de cellules en suspension dans un milieu reconstitue a partir d'une eau incubee avec le materiau a tester. Pour respecter les conditions reelles d'exploitation et de distribution des eaux potables, nous avons mesure l'effet du relargage de toxiques au cours des trois essais successifs suivants : dans une eau ultra-pure, avant et apres chloration, puis apres marnage. Des mesures effectuees sur un grand nombre de materiaux ont mis en evidence l'independance des reponses des trois essais.Pour etre satisfaisant de point de vue sanitaire, le materiau ne doit pas presenter de toxicite manifeste dans aucun de ces trois essais.Par ailleurs, cette etude a mis en evidence une etroite correlation entre le test d'ancrage et le test de synthese d'ARN, temoignant que ces mesures de toxicite in vitro evaluent bien un reel etat de morbidite cellulaire.

At every step of a treatment plant the water toxicity was evaluated, without any concentration, by a cell culture assay and compared to the TOCl concentration. Optimized ozonation, as well as chlorine dioxide treatment, largely increased water quality. On the opposite, final chlorination induced as much toxic compounds as preceding ozonation was suboptimal. This study also demonstrated that 4 different toxic compounds were induced by different treatment steps from at least 2 non‐toxic precursors.

Studies were carried out on-site in a potable water production plant utilizing ozonation treatment at three stages of the process. The quality of water in the treatment line was studied by chemical analysis, but also for toxicity to Hela cells after XAD resin concentration, and for mutagenesis to Salmonella Ames strains and mammalian cells V79 HGPRT system. With a sufficient dose of ozone and activated carbon adsorption, the initial cytotoxicity of the raw water and the mutagenic or promoter activity are destroyed.

The ability of Bacillus strains to degrade geosmin, a musty off-flavor component present in superficial waters, led some authors to postulate the existence of a Bacillus exoenzyme: the “geosminase”. Such an enzyme, as an immobilized form onto a granular material, would be of a great interest to remove geosmin from water. This prospect prompted us to look for geosminase in Bacillus cultures. An aqueous solution of pure geosmin was added to Bacillus culture supernatants from exponential or stationary phases, and to a whole culture induced for 24 hours with 0.06 ppm of geosmin. Geosmin was determinated by GLC as a function of incubation time. No evidence of enzymatic activity was obtained, but an important adsorption of geosmin onto glass vessels was observed at neutral pH (6.7–7.5). Geosmin was recovered from glass by elution with methanol. Thus great care must be taken before assuming a biological origin to geosmin disappearance from superficial waters. However, preliminary results indicate that a “true” geosminase can be detected in Actinomycete lysates. The characterization and the purification of this enzyme are actually in progress.

En 1981, le Centre de Recherche et de Controle des Eaux de la Ville de Paris a mis au point, pour le Ministere de la Sante, un ensemble de tests permettant d'evaluer la qualite des materiaux en contact avec l'eau potable. Cet ensemble de tests appliques dans des conditions proches des conditions reelles d'exploitation comprend des mesures de criblage rapide, des mesures physicochimiques et des mesures de cytotoxicite. Pres de 200 materiaux ont ete soumis au premier test de criblage rapide, qui comporte les determinations organoleptiques. Le mauvais gout est responsable du rejet de la moitie d'entre eux. Parmi les 77 materiaux soumis aux analyses physicochimiques fines, apres avoir satisfait aux mesures de criblage rapide, 7 % sont elimines. L'elimination a dans ce cas deux causes principales : ou bien il s'agit de composes pris en compte par la legislation de la CEE qui sont presents a des concentrations superieures aux limites admises, ou bien il s'agit de composes ne figurant pas dans la legislation de la CEE mais dont la presence est anormale. Les 53 materiaux ayant subi avec succes les deux premiers tests sont ensuite soumis a deux tests independants de cytotoxicite. Une correlation extremement etroite entre les deux tests a ete mise en evidence. Elle montre que l'evaluation de la toxicite par les systemes in vitro est quantitative, reproductible et qu'elle correspond a un reel etat de pathologie cellulaire. Cette correlation, temoin de la signification des tests de cytotoxicite, a abouti au refus de 23 % des materiaux qui leur ont ete soumis.

To set up an in vitro cytotoxicity test much more sensitive that the currently available tests, toxic samples were directly assayed on eleven different human cell subcellular targets. This comparison clearly indicated that the rapidity of cellular RNA synthesis was the most sensitive target to many pollutants. When used in the water field this quantitative test does not require preliminary concentration of the water toxic compounds and, in the case of polluted river waters, requires the samples to be diluted. The application domain of the test was shown to be very large, ranging from surface and ground waters to drinking and mineral bottled waters.

Ce travail propose de nouvelles methodes permettant la mise en evidence rapide de la cytotoxicite des eaux sans concentration prealable. Certaines, globales, permettent l'etude de l'action de differents toxiques sur les syntheses vitales de la cellule humaine : ADN, ARN et proteines ; d'autres plus simples font appel a differentes enzymes extraites des memes cellules, et donnent des reponses plus specifiques. Des cellules humaines ont ete cultivees durant 2 heures ou 24 heures en presence de differentes eaux de Seine transformees en milieu de culture. La mesure des syntheses d'ADN et d'ARN des cellules ainsi cultivees, montre qu'au bout de 24 heures toutes les eaux de Seine se sont revelees toxiques a des degres divers, demontrant par la meme la grande sensibilite et la rapidite de ces methodes.

With a 34% efficiency, not related to the amount of viruses, a simple and inexpensive apparatus allows quantitative recovery of enteroviruses from river-water.

The trophozoïts of Acanthamoeba castellanii are unable to adsorb poliovirus or vesicular stomatitis Virus. After encystment in medium containing respectively 5.4 x 10(8) and 3 x 10(9) P.F.U./ml cysts did not contain Viruses. These data do not agree with a current hypothesis by which water's free Amoeba could carry animal Viruses.

A ribonuclease associated with purified vaccinia virus is able to degrade into 3S fragments the viral 8–12S mRNAs synthesized in vitro . This RNase not detected on purified viral cores was shown to be located on the outer side of the viral envelope. When added to reaction mixture, a partially purified HeLa S3 cytosol fully inhibits the vaccinia virus associated RNase. Other cytosols from very common mammalian cell lines also contain RNase inhibitor and are of interest in order to prepare large amounts of undegraded vaccinia virus mRNAs.

A ribonuclease associated with vaccinia virus can be detected when reduced concentrations of nucleotides are used for an in vitro RNA synthesis assay. The non-viral origin of this ribonuclease may be inferred from its external location and from its variable activity on different purified virus stocks. The detection of this ribonuclease activity on purified virus grown without foetal Calf serum may suggest that this enzyme is of cellular origin.