The transpososome: control of transposition at the level of catalysis.

Studies of several transposable genetic elements have pinpointed the importance of the transpososome, a nucleoprotein complex involving the transposon ends and a transposon-encoded enzyme--the transposase--as a key in regulating transposition. Transpososomes provide a precise architecture within which the chemical reactions involved in transposon displacement occur. Data are accumulating that suggest they are dynamic and undergo staged conformational changes to accommodate different steps in the transposition pathway. This has been underpinned by recent results obtained particularly with Tn5, Tn10 and bacteriophage Mu.

[Pilocytic astrocytoma of the conus medullaris]. / Astrocytome pilocytique du cône médullaire.

We report the case of a rare glial tumor of the conus medullaris classified as pilocytic astrocytoma in a young adult. This tumor is most commonly found in the brain. The imaging findings will be correlated with the findings at histology. The literature will also be reviewed.

[An anterior mediastinal mass]. / Une masse médiastinale antérieure.

A 50-year-old man developed a bronchogenic cyst complicated by hemorrhage. A complete radiographic chest work-up provided a reliable diagnostic approach. Bronchogenic cysts are usually asymptomatic incidental discoveries. Chest ultrasonography confirms the cystic nature of the mediastinal mass. Computed tomography scan and especially magnetic resonance imaging further support the diagnosis and are helpful for guiding surgery. Surgery is required because of the unpredictable risk of hemorrhage, infection or enlargement.

[The eosinophilic lung]. / Le poumon eosinophile.

Eosinophilic lung disease comprises a diverse group of disorders characterized by eosinophilic pulmonary infiltration in association with other inflammatory cells. In patients with respiratory symptoms, usually associated with radiographically documented infiltrates, blood eosinophilia is a helpful but inconsistent diagnostic finding. Currently diagnosis is confirmed more often by bronchoalveolar lavage than by lung biopsy. Possible etiologies include parasites, mycotic agents, drugs, and angeitis. Remaining cases are classified as idiopathic eosinophilic lung disease including Carrington's disease, idiopathic hypereosinophilic syndrome, acute eosinophilic pneumonia, and Loeffler's syndrome. Mild eosinophilia is also a possible finding of bronchoalveolar lavage in several other disorders but the role of eosinophils is less important. The prognosis and treatment of eosinophilic lung disease varies depending on etiology. Corticosteroids are frequently used but treatment modalities also depend on etiology.

[Role of MRI in spinal and spinal cord emergencies]. / Place de l'IRM dans l'urgence rachidienne et médullaire.

Out of 137 cases concerning the spine and spine cord, the authors demonstrate that MRI is nowadays fully integrated in urgency investigations. In all cord compression suspicions and in spine trauma investigations, it's place is found. Coil and software improvements allow to put CT and MR scanning delays on a line. This study underlines the necessity of being equipped with non magnetic life support systems allowing management of very fragile patients. In traumas, MR provides the lesion's authentification, it's type, it's unique localisation or not, and therefore an early functional prognosis. The discovery of spine cord involving lesions in neoplastic conditions allows to follow a therapeutic strateging for maintaining the motor function. In the end, the authors discuss about practical utility of MR in scuba diving decompression accidents. No lesion of the spine cord has been demonstrated in 25 patients, probably because of technical insufficiency.

Juvenile nasopharyngeal angiofibroma: comparison of blood loss during removal in embolized group versus nonembolized group.

PURPOSE: This retrospective study was performed to assess the beneficial effect of preoperative embolization of juvenile nasopharyngeal angiofibromas (JNA) in terms of blood loss during surgery. METHODS: Intraoperative blood loss in a group of 7 patients who underwent 10 procedures for JNA without preoperative embolization was compared with the blood loss of 13 patients who underwent 16 procedures after embolization of one or both external carotid arteries. RESULTS: Mean blood loss was 5380 ml in patients without embolization and 1037.5 ml in those with embolization. This difference was not statistically significant because of the high standard deviation in the nonembolized group. However, when data were analyzed by tumor stage, a significant difference was noted between the embolized and the nonembolized patients with high-grade tumors but not between those with low-grade tumors. CONCLUSION: Preoperative embolization of the branches of the external carotid appears to facilitate removal of high grade tumors. The benefit of embolization in those with low-grade tumors is less clear cut, probably because there is less vascularity in low-grade tumors and so removal is easier.

[Correlations between clinical examination/MRI/arthroscopy in the acute traumatic knee]. / Corrélations examen clinique/IRM/arthroscopie dans le genou traumatique aigu.

Authors study retrospectively 81 cases of isolated recent (less than three months) knee traumas. These include clinical aspects, NMR, arthroscopy. Clinical examinations have been graded: 1. possible lesion; 2. likely lesions; 3. confirmed lesions. Clinical examinations and NMR results are compared to arthroscopy considered as reference. Clinical examination of acute traumatic knee is essential. Nevertheless, its value for detecting precise lesions is poor, except for knee locking well correlated with meniscal tears. Results show that NMR provide better results than clinical examination. NMR is reliable for detecting tears of posterior cruciate ligament, tears of posterior horn of menisci (sensibility: 93%; specificity: 80%). Its results are less effective for appreciation of lesion of anterior cruciate ligament (sensibility: 88%; specificity: 78%) because of partial tears and functional but not morphologic damage. It is the only method able to evidence osteochondral injuries and soft-tissues associated lesions in traumatic knees. Emergency NMR scans show results no differences in results compared with routine examinations. However, one should keep in mind that negative NMR cannot exclude small cartilaginous lesions and partial tears of anterior cruciate ligament. According to these results and the known qualities of NMR (non invasive), we propose that this type of investigation should be more largely included in diagnostic attitude for acute injured knee. Emergency diagnostic arthroscopy could be efficiently replaced by NMR knee examination.

[Lipoblastic meningioma. An uncommon benign tumor]. / Méningiome lipoblastique. Une tumeur bénigne surprenante.

Often mentioned and not much documented, the lipoblastic meningioma is an unusual extra-axial benign tumor. It has spontaneously hypodensity in CT and appears with a high signal in MRI in T1-weighted sequence. Its vascularisation is rich and shows a strong contrast intake. Its resection is known as easy and its prognosis is excellent. The authors report here the observation of a 65 year old women having a lipoblastic meningioma. Literature is gone through and differential diagnoses are considered.

[Correlations between the clinical test/MRI/arthroscopy in acute knee injuries]. / Corrélations examen clinique/IRM/arthroscopie dans le genou traumatique aigu.

Authors study retrospectively 81 cases of isolated recent (less than three months) knee traumas. These include clinical aspects, NMR, arthroscopy. Clinical examinations have been graded: 1. possible lesion; 2. likely lesions; 3. confirmed lesions. Clinical examinations and NMR results are compared to arthroscopy considered as reference. Clinical examination of acute traumatic knee is essential. Nevertheless, its value for detecting precise lesions is poor, except for knee locking well correlated with meniscal tears. Results show that NMR provide better results than clinical examination. NMR is reliable for detecting tears of posterior cruciate ligament, tears of posterior horn of menisci (sensibility: 93%; specificity: 80%). Its results are less effective for appreciation of lesion of anterior cruciate ligament (sensibility: 88%; specificity: 78%) because of partial tears and functional but not morphologic damage. It is the only method able to evidence osteochondral injuries and soft-tissues associated lesions in traumatic knees. Emergency NMR scans show results no differences in results compared with routine examinations. However, one should keep in mind that negative NMR cannot exclude small cartilaginous lesions and partial tears of anterior cruciate ligament. According to these results and the known qualities of NMR (non invasive), we propose that this type of investigation should be more largely included in diagnostic attitude for acute injured knee. Emergency diagnostic arthroscopy could be efficiently replaced by NMR knee examination.

[Neurocysticercosis of spinal manifestation. Apropos of a case]. / Neurocysticercose à révélation spinale. A propos d'un cas.

A case of spinal extramedullary cysticercosis with location in basal cisterns is reported. It was revealed by a severe sciatalgia and studied with MR imaging which is precious for the diagnosis and the follow-up. Cerebral cisternal arachnoiditis is the main problem in this racemose form where long medical treatment is necessary.

[The adipose tissue of the pelvis in imaging technics]. / Le tissu adipeux du pelvis en imagerie.

Fat is a fundamental contrast agent in pelvic imaging. The features of fat are typical on CT and MRI but vary on ultrasonography according to the physical characteristics and histology. The study of pelvic fat is of great importance in pelvic exploration because fat outlines both the normal structures and their borders. Involvement or masking of the pelvic fat is a good marker of carcinologic spread. Changes in pelvic fat may also be observe in inflammatory diseases. Specific diseases of fatty pelvic connective tissue such as lipomatosis and liposarcomas, are classically described. Teratomas with a fatty component derived from pelvic structures (ovaries) are easily diagnosed using imaging methods.