Genome shuffling enhances biocontrol abilities of Streptomyces strains against two potato pathogens.

AIMS: To employ the genome shuffling technique for improving the phenotype of a biocontrol control agent of the genus Streptomyces. METHODS AND RESULTS: Two rounds of genome shuffling (GS) were carried out with Streptomyces melanosporofaciens EF-76, a geldanamycin producer. Six fusants that showed optimized in vitro antagonistic activity against Streptomyces scabies or Phytophthora infestans, two important pathogens of potato crops, were selected. All selected fusants retained the capacity to produce geldanamycin, but none overproduced this antibiotic. The higher antagonism ability appeared to result from a diversification of secreted metabolites. Seven or eight metabolites were detected in the HPLC profiles of parental strains, whereas 12-15 were detected in fusant strains. Biocontrol assays revealed that four of six fusants protected tubers more efficiently than parental strains. CONCLUSIONS: GS emerged as an elegant and rapid tool to optimize the antagonistic ability of Streptomyces strains. Optimization of the in vitro antagonistic activity against plant pathogens appears to be an effective approach to select for improved biocontrol agents. The enhanced phenotype did not depend on an overproduction of a specific antibiotic but rather on the secretion of a wider variety of secondary metabolites. SIGNIFICANCE AND IMPACT OF THE STUDY: Improved capacities of a biocontrol agent compensate for the lack of efficient chemical control of potato scab.

[Evaluation of the predictive value of fibrin degradation products in the detection of deep venous thrombosis after total knee prosthesis]. / Evaluation de l'intérêt prédictif des produits de dégradation de la fibrine (PDFb) en ELISA dans le dépistage des thromboses veineuses profondes après prothèse totale du genou.

The total knee arthroplasty (TKA) favours deep venous thrombosis (DVT), more often sural thrombosis. In this case, pulmonary embolism is exceptional but sural thrombosis can give a poor functional prognostic by trophic disorders. The purpose of this work is to verify the predictive value of D-Dimer by Elisa technic in the detection of DVT after TKA. We have studied 42 TKA at the Edouard HERRIOT Hospital(Lyon) between April 2, 1992 and October 20, 1994. Patients were divided in two groups: with DVT (n = 5) and without DVT (n = 37). Prophylactic heparinotherapy was systematic. The biologic follow-up by ELISA technic(Fibrinostika FbDP, Organon Teknika) of the D-Dimer were realized at D0 (Day 0) preoperative period and D1, D4, and D6 postoperative period. An echo-Doppler exam were effected at D8 postoperative. The analysis of mean rate of the D-Dimer didn't show significative difference between the two groups at D0, D1, D4 and D6. But, we observed that the rate of D-Dimer increased after TKA significantly in both groups. We can't evaluate predictive interest of the D-Dimer after TKA but the little number of DVT authorizes to pursue this study and to moderate our conclusion.

[Analysis of restraint of the femur head. Experimental study of allograft of cold bone and autoclaved bone to kill the HIV virus]. / Analyse des contraintes de l'extrémité supérieure du fémur. Etude expérimentale allogreffes os congelés - os autoclaves en vue de la destruction du virus H.I.V.

The retrovirus S.I.A.D. grown in marrow bone and iatrogenic infections may be possible after bone graft in following total hip arthroplasties. Previous investigators proposed several methods to kill the virus, but without bacteriological safety. They found 20 to 55% of loss on mechanical properties. The present study reports the response of autoclaved femoral heads compression testing on material machine Model 1026 Instron. The stress response of marrow bone to stains showed a classic peak and with linear regression study we saw a relationship between autoclaved bone and cold bone. The cortical bone resists to strains highly 12% of load.

Randomized trial of a low-molecular-weight heparin (Kabi 2165) versus adjusted-dose subcutaneous standard heparin in the prophylaxis of deep-vein thrombosis after elective hip surgery.

124 patients undergoing total hip replacement were randomly allocated to receive Kabi 2165, 2,500 anti-Xa units twice a day (group A); Kabi 2165, 2,500 anti-Xa units twice a day during the first 48 h postoperatively and then 5,000 anti-Xa units once a day (group B), or adjusted-dose standard heparin, monitored by activated partial thromboplastin time (group C). The first dose was given 2 h before surgery in the three groups. Deep-vein thrombosis (DVT) was detected by radiolabelled fibrinogen uptake and bilateral venography was performed in patients who had a positive scan. In patients who had a negative scan, bilateral venography was performed routinely the day before discharge from hospital. The frequency of DVT demonstrated by venography was 4.9% in group A, 7.3% in group B and 10% in group C. The difference between the three groups was not statistically significant. The incidence of proximal DVT was 2.4, 2.4 and 7.5%, respectively, for the three groups. There was no significant difference between the three groups with respect to mean estimated blood loss, the number of blood units transfused, wound hematoma formation, or hemoglobin and hematocrit levels.

[The radioimmunological assay of fibrinogen breakdown products with E antigen during postoperative venous thromboses. Study in 46 cases of arthroplasty for osteoarthrosis of the hip (author's transl)]. / Le dosage radioimmunologique des produits de dégradation du fibrinogène possédant l'antigène E, au cours des thromboses veineuses post-opératoires. Etude à l'occasion de 46 arthroplasties pour coxarthrose.

Twenty six patients (without thrombosis) had a normal 125I-fibrinogen test, among whom 15 had a normal phlebography; 18 patients (with thrombosis) had a positive 125I-fibrinogen test among whom 11 had a positive phlebography. There was a discrepancy between phlebography and 125I-fibrinogen test in 2 patients. In patients with thrombosis, there is a significantly increase of FgE levels for several days after the intervention. However the measurement of FgE is not a reliable test (4% of false positive and 38% of false negative); but it is always elevated in femoral and popliteal thrombosis.