Possible land management uses of common cypress to reduce wildfire initiation risk: a laboratory study

Accurate determination of flammability is required in order to improve knowledge about vegetation fire risk. Study of the flammability of different plant species is essential for the Mediterranean area, where most ecosystems are adapted to natural fire but vulnerable to recurrent human-induced fires, which are the main cause of forest degradation. However, the methods used to evaluate vegetation flammability have not yet been standardized. Cupressus sempervirens is a native or naturalized forest tree species in the Mediterranean area that is able to tolerate prolonged drought and high temperatures. The aim of this study was to characterize the flammability of C. sempervirens var. horizontalis at particle level by using different bench-scale calorimetry techniques (mass loss calorimeter, epiradiator and oxygen bomb) to determine the main flammability descriptors (ignitability, sustainability, combustibility and consumability) in live crown and litter samples. Our findings indicate that this variety of cypress is relatively resistant to ignition because of the high ash content, the high critical heat flux, the high time to ignition displayed by both crown and litter samples and the ability of the leaves to maintain a high water content during the summer. We also discuss the possibility of exploiting some morphological, functional and ecological traits of the species to construct a barrier system (with selected varieties of cypress) as a promising complementary land management tool to reduce the fire spread and intensity in a Mediterranean context.

Influence of high mutation rates on the mechanisms and dynamics of in vitro and in vivo resistance development to single or combined antipseudomonal agents

We studied the mechanisms and dynamics of the development of resistance to ceftazidime (CAZ) alone or combined with tobramycin (TOB) or ciprofloxacin (CIP) in vitro and in vivo (using a mouse model of lung infection with human antibiotic regimens). Pseudomonas aeruginosa strain PAO1 and its hypermutable derivative PAODeltamutS were used, and the results were compared with those previously obtained with CIP, TOB, and CIP plus TOB (CIP-TOB) under the same conditions. An important (200-fold) amplification of the number of resistant mutant cells was documented for PAODeltamutS-infected mice that were under CAZ treatment compared to the number for mice that received placebo, whereas the median number of resistant mutant cells was below the detection limits for mice infected by PAO1. These results were intermediate between the high amplification with CIP (50,000-fold) and the low amplification with TOB (10-fold). All CAZ-resistant single mutant cells selected in vitro or in vivo hyperproduced AmpC. On the other hand, the three combinations studied were found to be highly effective in the prevention of in vivo resistance development in mice infected with PAODeltamutS, although the highest therapeutic efficacy (in terms of mortality and total bacterial load reduction) compared to those of the individual regimens was obtained with CIP-TOB and the lowest was with CAZ-CIP. Nevertheless, mutant cells that were resistant to the three combinations tested were readily selected in vitro for PAODeltamutS (mutation rates from 1.2 x 10(-9) to 5.8 x 10(-11)) but not for PAO1, highlighting the potential risk for antimicrobial resistance development associated with the presence of hypermutable strains, even when combined therapy was used. All five independent CAZ-TOB-resistant PAODeltamutS double mutants studied presented the same resistance mechanism (AmpC hyperproduction plus an aminoglycoside resistance mechanism not related to MexXY), whereas four different combinations of resistance mechanisms were documented for the five CAZ-CIP-resistant double mutants.

Transcervical falloposcopy: preliminary experience

The new technique of endoluminal tubal exploration was evaluated by performing transcervical falloposcopy instead of chromoperturbation under control of concurrent laparoscopy. In this feasibility study, catheterization was performed with the use of either a transhysteroscopic or a free-hand tubal cannulation technique. A total of 66 patients were investigated for primary or secondary infertility with proximal and/or distal suspected tubal defects on the basis of prior hysterosalpingography; three patients were investigated for unruptured tubal pregnancy; two patients were investigated to localize the tip of the tubal embryo transfer catheter. Transcervical catheterization was successful in 110 of the 130 tubes (84.6%). Successful and informative falloposcopy was achieved in 30% of the 110 cannulated tubes. The transcervical free-hand cannulation technique was as effective as the transhysteroscopic approach. Recanalization of at least one tube was achieved in 83% of women with proximal obstruction. Tubal cannulation by the tubal embryo transfer catheter was confirmed by falloposcopy in the two cases where free-hand catheterization was used. This study confirms that it is possible to visualize the tubal lumen and demonstrates that the free-hand cannulation technique is a simple and effective alternative to the transhysteroscopic approach. However, further progress in catheter technology has to be achieved in order to perform regularly successful transcervical falloposcopy in damaged tubes.