Representations of pesticides and social practices: the case of French farmers.

Pesticides and their use in agriculture are important social issues. We conducted research to study the construction of this sensitive social object through the lens of social representations (study of the structural organisation of the social representations of pesticides) and their anchoring in three contexts that differ in terms of farming practices (Martinique, Brittany and Southern France). Our research was composed of two phases: hierarchical associations (n = 213) and a context independence test questionnaire (n = 124), conducted among farmers from the three study sites. The results indicate three representational fields that reflect salient issues in each agricultural territory. These illustrate the heuristic nature of social representations in the analysis of agricultural practices and pesticide use among French farmers.

Study of the cytolethal distending toxin (CDT)-activated cell cycle checkpoint. Involvement of the CHK2 kinase.

The bacterial cytolethal distending toxin (CDT) triggers a G2/M cell cycle arrest in eukaryotic cells by inhibiting the CDC25C phosphatase-dependent CDK1 dephosphorylation and activation. We report that upon CDT treatment CDC25C is fully sequestered in the cytoplasmic compartment, an effect that is reminiscent of DNA damage-dependent checkpoint activation. We show that the checkpoint kinase CHK2, an upstream regulator of CDC25C, is phosphorylated and activated after CDT treatment. In contrast to what is observed with other DNA damaging agents, we demonstrate that the activation of CHK2 can only take place during S-phase. Use of wortmannin and caffeine suggests that this effect is not dependent on ATM but rather on another as yet unidentified PI3 kinase family member. These results confirm that the CDT is therefore responsible for specific genomic injuries that block cell proliferation by activating a cell cycle checkpoint.

[Use of muscular flaps for the treatment of open fractures of limbs. Apropos of 42 cases]. / Utilisation des lambeaux musculaires dans le traitement des fractures ouvertes des membres. A propos de 42 cas.

PURPOSE OF THE STUDY: Since 1988, skin defect associated with upper (6 cases) or lower (34 cases) limb fractures were treated in our Orthopaedic Department with regional or free muscular flaps. The aim of this study was to demonstrate that muscular flaps represent a treatment of choice for infection prevention and consolidation. MATERIAL AND METHODS: 42 patients have been treated: 29 Cauchoix III or IV, 12 secondary exposed fractures, 1 amputation. A total of 42 flaps, including 28 regional flaps and 14 microvascular free-tissue transfers were performed. A first stage included thorough debridement, fixation with external fixator in 85 per cent, and revascularization (4 cases). A second look was necessary in all but 3 cases: flap coverage was performed at this stage. A bone graft was proposed in 17 cases after a mean time of 3 months and 20 days. RESULTS: Bony healing was found in 37 cases (86.5 per cent) with a mean delay of 7 months 20 days. 5 patients required another method of treatment because of flap necrosis or non-union, with an average time to bony healing of 13 months. 42 tissue transfers were performed with an overall success rate of 95.3 per cent (2 necrosis of latissimus dorsi flaps). 3 partial necrosis involved 2 regional and 1 free flap. One of them needed another treatment. No infection was encountered in 40 cases (95 per cent) even if most of the patients were treated after initial treatment elsewhere. DISCUSSION: Experience with regional muscle transfer has advocated the gastrocnemius and proximal pedicle medial soleus as reliable and excellent choice for reconstruction of the proximal and middle third of the leg. Latissimus dorsi transfer, which can be used totally, partially, or as a "vascular graft flap" represent the treatment choice for extensive upper or lower limb exposed fracture especially for distal lower limb fracture (exposure of the tibia). Muscle flap coverage in the acute period (within 48 or 72 hours) remains for us the best treatment.

The use of MR images to evaluate the risks associated with proximal locking of intramedullary tibial nails.

Vascular complications associated with locked intramedullary tibial nailing are infrequent but always serious, with a secondary amputation rate of 30%. These complications, based on an MR study of the anatomic relationships between the interlocking screws and the neurovascular or articular structures at the proximal end of the tibia, have been analysed. Two types of nails were used: one with anterior-posterior locking and a specially designed prototype with oblique locking. In particular this study emphasised the anatomic risk of injury to the popliteal structures when using anterior-posterior locking, as well as to the anterior tibial vessels and proximal tibiofibular joint when using oblique locking. As no locking method appears to be better than any other, the best is that associated with the lowest morbidity. Consequently, the use of frontal instead of anterior-posterior locking is recommended; the use of oblique locking, which this study has shown carries a much higher risk of complications, is strongly advised against.