A time-dependent order parameter for ultrafast photoinduced phase transitions.

Strongly correlated electron systems often exhibit very strong interactions between structural and electronic degrees of freedom that lead to complex and interesting phase diagrams. For technological applications of these materials it is important to learn how to drive transitions from one phase to another. A key question here is the ultimate speed of such phase transitions, and to understand how a phase transition evolves in the time domain. Here we apply time-resolved X-ray diffraction to directly measure the changes in long-range order during ultrafast melting of the charge and orbitally ordered phase in a perovskite manganite. We find that although the actual change in crystal symmetry associated with this transition occurs over different timescales characteristic of the many electronic and vibrational coordinates of the system, the dynamics of the phase transformation can be well described using a single time-dependent 'order parameter' that depends exclusively on the electronic excitation.

Structural and magnetic dynamics of a laser induced phase transition in FeRh.

We use time-resolved x-ray diffraction and magneto-optical Kerr effect to study the laser-induced antiferromagnetic to ferromagnetic phase transition in FeRh. The structural response is given by the nucleation of independent ferromagnetic domains (τ(1)~30 ps). This is significantly faster than the magnetic response (τ(2)~60 ps) given by the subsequent domain realignment. X-ray diffraction shows that the two phases coexist on short time scales and that the phase transition is limited by the speed of sound. A nucleation model describing both the structural and magnetic dynamics is presented.

Femtosecond dynamics of the collinear-to-spiral antiferromagnetic phase transition in CuO.

We report on the ultrafast dynamics of magnetic order in a single crystal of CuO at a temperature of 207 K in response to strong optical excitation using femtosecond resonant x-ray diffraction. In the experiment, a femtosecond laser pulse induces a sudden, nonequilibrium increase in magnetic disorder. After a short delay ranging from 400 fs to 2 ps, we observe changes in the relative intensity of the magnetic ordering diffraction peaks that indicate a shift from a collinear commensurate phase to a spiral incommensurate phase. These results indicate that the ultimate speed for this antiferromagnetic reorientation transition in CuO is limited by the long-wavelength magnetic excitation connecting the two phases.

[What to do with a normal urinary strip in case of lower urinary tract symptoms?]. / Symptômes urinaires bas et bandelette normale: à quoi penser?

Patients very often consult for lower urinary tract symptoms, that do not necessarily equate to common cystitis. When urinary leucocytes and nitrites are absent, the urinary strip has a very good negative predictive value and makes the diagnosis of a lower urinary tract infection very unlikely. One then has to search for other diagnoses and to clarify the nature of the symptoms, irritating or obstructive ones, their duration and to correlate them to the patient's age and gender. In sexually active young patients, infectious diseases predominate, such as uretritis or vaginitis, while, with age, the prevalence of dysfunction of vesical emptying, benign prostatic hyperplasia or atrophic vaginitis increase.

[Should we prescribe phosphodiesterase inhibitors for the treatment of symptomatic benign prostatic hyperplasia]. / Est-il opportun de prescrire des inhibiteurs de la phosphodiestérase pour traiter le prostatisme?

This October, the FDA has approved the use of phosphodiesterase inhibitors for the treatment of micurition symptoms due to benign prostatic hyperplasia, so as for erectile dysfunction. This decision is essentially based on the results of 2 studies that we discuss in this article. Although methodologically well designed, these works show that phosphodiesterase inhibitors decrease only weakly, but statistically sigificatively the micturition score of patients suffering from prostatism. Besides that, only one of these papers show a limited effect on a single objective micturitionnal parameter. According to the present knowledge, it appears judicious to prescribe tadalafil to treat benign prostatic hyperplasia symptoms of patients suffering simultaneously of a significant erectile dysfunction.

Female hydrocele: the cyst of Nuck.

The canal of Nuck is the portion of the processus vaginalis within the inguinal canal in women. A hydrocele of the canal of Nuck is equivalent to an encysted hydrocele of the cord in men. The literature reveals very little about this rare condition in the adult female patient. In this paper, we report a case of hydrocele of the canal of Nuck in a young female. The diagnosis was made with ultrasound and magnetic resonance imaging and then confirmed preoperatively and by histopathology. Although rare, a hydrocele of the canal of Nuck has to be included in the differential diagnosis of a groin lump in female patients.

[Acute renal colic: which radiological exam in the GP daily practice?]. / Colique néphrétique au cabinet: quel bilan radiologique pour quel patient?

Nephrolithiasis is a common disease. Acute renal colic due to migration of stone is a frequent cause of admission in emergencies departements (ED). Diagnostic procedures in such centers are already well codified. This article discuss the diagnostic management and particularly the question of the radiological evaluation in patients presenting with renal colic to the general practitioner (GP). Because of the high risk of recurence and in order to identify patients with high stone burden, every patient presenting a first episode of renal colic should undergo radiological investigation. Considering sensitivity, irradiation rate, cost and diagnostic information, we recommend the (low-doses CT-SCAN as exam of choice for initial radiological evaluation of patient with renal colic.

[Robot-assisted surgery in urology]. / Roboterassistierte Operationen in der Urologie.

Since 1990, laparoscopic surgery has undergone a tremendous evolution. As patients and surgeons alike push toward minimally invasive surgery, more and more complex operations have been performed by laparoscopy. However, highly complex and technically demanding procedures--such as radical prostatectomy--have revealed the limits of classical laparoscopic surgery. The introduction of the Da Vinci robot has changed the face of modern laparoscopy because it provides the surgeon with three-dimensional vision, more instrumental degrees of freedom, and greater ergonomics. Thus, laparoscopy has been able to strengthen its role in urology and is increasingly being used for radical prostatectomies, pyeloplasties, and ureteral operations such as ureterovesical reimplantations. For most types of operations, functional and early oncological outcomes appear similar to those of conventional laparoscopy or open surgery. The main drawbacks of robotic surgery are the costs of the disposable instruments and maintenance, which overshadow the initial purchase price. The near future will show how European health systems will react to this new financial burden. Our institution, within a university hospital with moderate patient recruitment, was equipped with a four-arm Da Vinci robot in February 2006. As of April 2008, 120 urological operations had been performed. Because robotic surgery is associated with a specific learning curve, divisions with limited case numbers may refrain from doing this type of surgery. The aim of this article is to evaluate the feasibility and efficiency of the initial period of a robotic program in a midsize division.

[Minimally invasive ablation techniques for small kidney tumors: cryoablation and radiofrequency]. / Traitement minimalement invasif des petites tumeurs du rein par cryothérapie et radiofréquence.

Over the last years, the development of minimally invasive surgery using percutaneous or laparoscopic ablative techniques for the treatment of small renal tumours has become more common. Cryotherapy and radiofrequency option have been now integrated in the armamentarium of the urologist. These approaches seem to be an attractive alternative to extirpative surgery in selected high-risk patients and offer on a short time basis equivalent cancer control to conventional surgery. This review presents recent data with regard to the use of cryotherapy and radiofrequency in the treatment of small renal tumours. These techniques will obviously have to stand the test of time.

[Usefullness of the Da Vinci robot in urologic surgery]. / Utilité du robot Da Vinci en chirurgie urologique.

A telemanipulator for laparoscopic instruments is now available in the world of surgical robotics. This device has three distincts advantages over traditional laparoscopic surgery: it improves precision because of the many degrees of freedom of its instruments, and it offers 3-D vision so as better ergonomics for the surgeon. These characteristics are most useful for procedures that require delicate suturing in a focused operative field which may be difficult to reach. The Da Vinci robot has found its place in 2 domains of laparoscopic urologic surgery: radical prostatectomy and ureteral surgery. The cost of the robot, so as the price of its maintenance and instruments is high. This increases healthcare costs in comparison to open surgery, however not dramatically since patients stay less time in hospital and go back to work earlier.

A randomized prospective study of cefepime plus metronidazole with imipenem-cilastatin in the treatment of intra-abdominal infections.

BACKGROUND: Presumptive antimicrobial therapy is an important aspect of the management of intra-abdominal infections. Together with surgery, antimicrobial combinations are still widely used to achieve the required spectrum of activity. The aim of this study was to evaluate the efficacy of parenteral cefepime + metronidazole vs imipenem-cilastatin for the treatment of intra-abdominal infections in adult patients. METHODS: Patients with a clinically confirmed diagnosis of intra-abdominal infection were randomized to one of two treatment regimens: cefepime 2 g iv/12 h plus metronidazole 500 mg/8 h or imipenem-cilastatin 500 mg iv/6 h. The primary measure of clinical response was the decline of pre-treatment signs and symptoms of infection. The duration of follow-up was 30 days. Treatment failure was defined as either a lack of improvement or a worsening of pre-treatment signs and symptoms of infection. Surgical management of the infection was determined by the surgeon-in-charge. RESULTS: Of the 122 intended-to-treat patients included in the study, 60 patients (33 men) were randomized to cefepime + metronidazole and 61 (27 men) to imipenem-cilastatin. Cefepime + metronidazole treatment was successful in 52 (87%) patients and imipenem-cilastatin in 44 (72%) patients (p = 0.004). Microbiological eradication was established in similar proportions in both groups (cefepime + metronidazole, 43; imipenem-cilastatin, 38). CONCLUSION: Further studies are warranted to confirm the better results with the cefepime + metronidazole regimen for the treatment of intra-abdominal infections.

Novel injectable urethral bulking agents for the treatment of urinary incontinence.

Stress urinary incontinence is a highly prevalent disorder resulting from weak urethral closure mechanisms. Endoscopic injection of a urethral bulking agent (UBA) under the urethral mucosa increases coaptation, which improves continence. Collagen is an efficient agent, although its effects are limited in time. Other materials still suffer either from a short-lasting effect or migration in distant organs. We evaluated here novel UBAs using an ex vivo model, with respect to criteria of ease of injection, ability to form a high and stable tissue bulking, implant elasticity and tissue reaction. One approach involves solutions of polymers in water-miscible organic solvents that precipitates in situ. In this manner, high and stable bulks were routinely obtained using various commercial polymers. Selected solvents reduced the tissue reaction to the implant. Microsphere suspensions in hydrogels also proved to be efficient UBA, although less stable bulks were obtained. Thermosetting chitosan hydrogels showed promising results with respect to bulk stability and isoelasticity with surrounding tissues. Different strategies have thus been compared and optimised ex vivo. Further experiments are required to compare the ability of these materials to induce a sustained in vivo bulking effect.