Sinonasal NK/T-cell lymphoma.

INTRODUCTION: Nasal NK/T-cell lymphoma is a rare but well-known clinical entity. Thanks to improvements in anatomopathology and the development of routine immunohistochemistry, the diagnosis of nasal NK/T-cell lymphoma (NK for "natural killer") was recognized by the WHO in 2001. The main differential diagnosis is with Wegener's granulomatosis. Treatment is based on radiotherapy and chemotherapy. Prognosis is poor, with variable evolution and sometimes rapid progression. CASE REPORT: The authors report the case of a 54-year-old man without known pathological history, who presented with bilateral nasal obstruction with purulent rhinorrhea. Diagnosis was made on the basis of immunohistochemical study of biopsy samples. The tumor was graded IE on the Ann Arbor classification. Treatment, comprising CHOP chemotherapy followed by radiotherapy, achieved total remission at 8 months' follow-up. DISCUSSION/CONCLUSION: Sinonasal NK/T-cell lymphoma is rare. Diagnosis is based on immunophenotypic and molecular characteristics. It is an aggressive lymphoma, requiring multidisciplinary management. Prognosis is poor.

Percutaneous mitral valvuloplasty through a Carpentier-Edwards ring.

The authors report the case of a young girl with a Carpentier-Edwards annuloplasty ring for severe rheumatic mitral disease who presented 4 years later with mitral restenosis due to commissural fusion. She underwent successful percutaneous mitral commissurotomy with an Inoue balloon. Technical specificities and the safety of the procedure are briefly discussed.

Guided waves in elastic plates with Gaussian section variation: experimental and numerical results.

Experimental and numerical results are presented on the behavior of guided waves in elastic plates in plane strain that include a Gaussian variation of their section, located between two areas of constant thickness. The area of varying section is wide compared to the used wavelengths, which allows wave propagation inside this area. The experimental results show that an incident Lamb wave is indeed converted into an adiabatic wave inside the varying section domain. A trapped wave in the Gaussian domain is also observed, depending on the incident mode and on the Gaussian maximum height. Outside the varying section domain, conversion into different Lamb waves is observed. This conversion phenomenon is experimentally quantified by the measurement of the Lamb wave normal displacement and of its carried energy. A numerical study, based on the Finite Elements Method is performed, and successfully compared to the experimental results.

[Left main coronary artery angioplasty: report of five cases illustrating the current indications]. / Angioplastie du tronc commun: a propos de cinq cas illustrant les indications actuelles.

OBJECTIVES: The purpose of our study is to illustrate by five original observations the various situations where the stenting of the left main coronary artery can be proposed in alternative to aortocoronary bridging with encouraging results in short- and long-term. MATERIALS AND METHODS: We report a retrospective study relating to five cases with left main disease treated by stenting between 1996 and 2002 at our institution. In two cases the left main stem was unprotected. In two other cases, the left main trunk was protected. And the last case was an emergency stenting for an iatrogenic dissection of the left main coronary artery. RESULTS: The stenting was carried out successfully among the five patients without major in-hospital complication. During the follow-up of 29 months at mean, no death was deplored, and no target lesion revascularization was required on the left main coronary artery (with a left main trunk permeable on three coronarographic controls). CONCLUSIONS: In the light of these results, and basing on the published data, we conclude that stenting for the left main coronary disease may be a safe and effective alternative to coronary artery bypass surgery in particular cases among "selected" patients (refusal or surgical contraindication, protected left main coronary artery, spontaneous or iatrogenic acute occlusion of the left main coronary artery).

[Percutaneous mitral commissurotomy and Lutembacher syndrome]. / Commissurotomie mitrale percutanée et syndrome de Lutembacher.

INTRODUCTION: Lutembacher syndrome refers to the rare combination of congenital atrial septal defect and acquired mitral stenosis. This condition is usually treated surgically by mitral valve operation with concomitant closure of the atrial septal defect. MATERIALS AND METHODS: Between 1993 and 2003, 4 patients with congenital Lutembacher syndrome had percutaneous mitral commissurotomy without closure of the atrial septal defect at our institution. The 4 patients were very symptomatic with right-sided heart failure signs and NYHA functional class III-IV. RESULTS: The procedure was carried out successfully for the four patients. Mitral valve area increased from 0.87 to 1.97 cm2 at mean; left atrial pressure decreased from 28.2 to 12.7 mmHg and the mean valve mitral gradient was reduced from 15.5 to 3.9 mmHg. Functional and clinical improvement was observed in all the cases. During a mean follow up of 55 +/- 29 months, our 4 patients remain pauci symptomatic under medical treatment. CONCLUSION: The percutaneous treatment of the Lutembacher syndrome is currently a possible alternative to the surgery among patients having an anatomy favourable to the procedure.

Guided waves in a plate with linearly varying thickness: experimental and numerical results.

The aim of this work is to give experimental and numerical results on the behaviour of guided waves that propagate downslope in a free elastic plate with slowly linearly varying thickness. We show experimentally the propagation of adiabatic modes, which are guided waves that adapt to the varying thickness of the plate. As the thickness is decreasing, a given guided wave will reach its thickness cut-off. When this happens, we show that two phenomena occur: the reflection of this wave and its propagation backward in the plate, its conversion into a different guided wave which goes on propagating downslope in the plate. The numerical study is done with the software Ansys, based on the finite element method. The results obtained confirm the experimental ones.

Tuberculosis of the sternoclavicular joint. Report of two cases.

The sternoclavicular joint accounts for only 1 to 2% of all cases of peripheral tuberculous arthritis and is more often infected by pyogenic organisms than by the tubercle bacillus. We report two cases of sternoclavicular joint tuberculosis, in a 38-year-old man and a 46-year-old woman without risk factors for immune deficiency. Swelling of the joint was the presenting manifestation. Laboratory tests indicated inflammation in only one of the patients. The intradermal tuberculin test was strongly positive in both patients, whereas smears and cultures of sputum and urine samples were negative for the tubercle bacillus. Serologic tests for the human immunodeficiency virus were negative. Erosions of the affected joint were seen by computed tomography. Histological studies of a surgical biopsy specimen confirmed the diagnosis. Cultures of the biopsy specimens were negative. The outcome was favorable after treatment with rifampin, isoniazid and pyrazinamide for six months in the man and nine in the woman. Follow-ups were eight and six months, respectively, at the time of this writing. Tuberculosis of the sternoclavicular joint is extraordinarily rare and can raise diagnostic problems. The diagnosis should be considered in every patient with arthritis in a sternoclavicular joint or unexplained pain in a shoulder. Possible complications include compression or erosion of the large blood vessels at the base of the neck and migration of tuberculous abscesses to the mediastinum.

Pathways for conformational change in seryl-tRNA synthetase from Thermus thermophilus.

Seryl t-RNA synthetase of the bacterium Thermus thermophilus contains a long arm, consisting of an antiparallel coiled coil, that is involved in binding of tRNA. Two crystallographic structures exist for this protein, in which the arm is in different conformations. Here, we use computational methods employing an empirical potential energy function to investigate the flexibility of the long arm. A conformational pathway is calculated between the 2 crystallographic structures using a method based on molecular dynamics simulation. The pathway is analyzed in terms of sequential phi and psi backbone angle changes. Several transient phi and psi displacements are present along the pathway that are not visible in the end states and may be required for transition between them. Energy maps are constructed by rotating the arm around its principal axes of inertia and energy minimizing. The map identifies 2 regions of relatively low energy which might be accessible to the arm.

An analysis of the conformational paths of citrate synthase.

Previous simulation studies have provided reaction pathways leading from the closed to the open form of citrate synthase. We now undertake a detailed analysis of these pathways using a variety of different tools including backbone dihedral angles, P-Curves helicoidal parameters, inter-helix geometrical parameters, and accessibility calculations. The results point to a relatively small number of residues, mostly in loop regions, which are responsible for the majority of the conformational changes observed. An important role is attributed to transient changes in the backbone which facilitate movement along the reaction coordinate. Comparisons between the two pathways show that they share many common features despite the different algorithms used to generate them.

Theoretical determination of conformational paths in citrate synthase.

Two methods are developed for the theoretical determination of a conformational path between two well-documented forms, a closed form and the open form [Remington et al. (1982) J. Mol. Biol. 158, 111-152] of pig heart citrate synthase, a dimeric enzyme of 2 x 437 residues. The first method uses the minimization of the sum of the potential energies at a set of equidistant points, according to Elber and Karplus [(1987) Chem. Phys. Lett. 139, 375-380]. The initialization of the algorithm is modified to account for large-angle rotations of many groups by performing the interpolations in the space of internal polar coordinates of a set of generalized Jacobi vectors earlier introduced by Durup [(1991) J. Phys. Chem. 95, 1817-1829] and by carefully testing all choices of directions of rotation for determining the initialized midpoint between the known forms. The path includes intermediate points, created by successive splittings of each interval into two equal parts, with a partial energy minimization performed after each splitting. The minimization encounters the well-known local-minima problem, which here is handled by low-temperature molecular dynamics annealing. It is shown that the best ratio of potential energy decrease to rms deviation is achieved by running the dynamics at 50 K, as compared to 100 K and above. The main character of the path obtained is the occurrence of strong to-and-fro variations of some dihedral angles at specific stages along the path. The second method, which we name directed dynamics, uses only low-temperature molecular dynamics simulations by starting trajectories from each of the two known forms with initial velocities directed toward the other one. The procedure is iterated by restarting trajectory pairs after the points of closest approach of the preceding pair. The two half-paths thus built eventually meet after 70 iterations. This method provides a second path with strong similarities, as well as some differences, with respect to the path obtained by the first method.