CEP-stable high-energy ytterbium-doped fiber amplifier.

We report on the carrier-envelope phase (CEP) stabilization of a Yb-doped fiber amplifier system delivering 30 µJ pulses at 100 kHz repetition rate. A single-shot, every-shot measurement of the CEP stability based on a simple f-2f interferometer is performed, yielding a CEP standard deviation of 320 mrad rms over 1 s. Long-term stability is also assessed, with 380 mrad measured over 1 h. This level of performance is allowed by a hybrid architecture, including a passively CEP-stabilized front-end based on difference frequency generation and an active CEP stabilization loop for the fiber amplifier system, acting on a telecom-grade integrated LiNbO3 phase modulator. Together with recent demonstrations of temporal compression down to the few-cycle regime, the presented results demonstrate the relevance of the Yb-doped high repetition rate laser for attoscience.

High flux circularly polarized gamma beam factory: coupling a Fabry-Perot optical cavity with an electron storage ring.

We report and discuss high-flux generation of circularly polarized γ-rays by means of Compton scattering. The γ-ray beam results from the collision of an external-cavity-enhanced infrared laser beam and a low emittance relativistic electron beam. By operating a non-planar bow-tie high-finesse optical Fabry-Perot cavity coupled to a storage ring, we have recorded a flux of up to (3.5 ± 0.3) × 108 photons per second with a mean measured energy of 24 MeV. The γ-ray flux has been sustained for several hours. In particular, we were able to measure a record value of up to 400 γ-rays per collision in a full bandwidth. Moreover, the impact of Compton scattering on the electron beam dynamics could be observed resulting in a reduction of the electron beam lifetime correlated to the laser power stored in the Fabry-Perot cavity. We demonstrate that the electron beam lifetime provides an independent and consistent determination of the γ-ray flux. Furthermore, a reduction of the γ-ray flux due to intrabeam scattering has clearly been identified. These results, obtained on an accelerator test facility, warrant potential scaling and revealed both expected and yet unobserved effects. They set the baseline for further scaling of the future Compton sources under development around the world.

Carrier-envelope phase drift measurement of picosecond pulses by an all-linear-optical means.

Carrier-envelope phase (CEP) drift of a pulse train of 2 ps pulses has been measured by a multiple beam interferometer. The round trip time of the interferometer is slightly mistuned from the pulse sequence, leading to spectral interference fringes. We extract the pulse-to-pulse CEP drift from the position of the spectral interference pattern. The length of the interferometer has been actively stabilized to ±10 nm, which sets the ultimate limit on the accuracy of the measurement to 78 mrad, while the CEP-drift (rms) noise of the measurement was 127 mrad (at 800 nm).

High finesse pulsed optical cavity locking by tilt-locking technique.

We report the Tilt-Locking (TL) technique applied to lock a laser in pulsed regime to a 28,000 high finesse Fabry-Perot cavity. Preliminary experimental results show that TL technique is comparable with the well-known Pound-Drever-Hall technique. This study is the first to implement the TL technique to lock a pulsed laser to a high-finesse optical cavity. Very high and stable coupling is obtained. The coupling rate is ~80%, and locking can last for more than 1 h. Furthermore, while previously published papers have focused on near field case, in this study we will give the error signal shape simulation for the far field case. We will show that for different types of error sources, the split photodiode transverse position can be carefully adjusted to obtain a symmetrical error signal. Our experimental results are consistent with the simulations.

External cavity enhancement of picosecond pulses with 28,000 cavity finesse.

We report on the first demonstration, to the best of our knowledge, of the locking of a Fabry-Perot cavity with a finesse of 28,000 in the pulsed regime. The system is based on a stable picosecond oscillator, an ultrastable cavity with high-reflection mirrors, and an all-numerical feedback system that allows efficient and independent control of the repetition rate and the pulse to pulse carrier-to-envelop phase drift (CEP). We show that the carrier to envelop phase can have a dramatic effect even for pulses with hundreds of cycles. Moreover, we have succeeded in unambiguously measuring the CEP of a 2 ps pulse train. Finally, we discuss the potential of our findings to reach the MW average power level stored in an external cavity enhancement architecture.

[Elevation of PSA after prostate radiotherapy: rebound or biochemical recurrence?]. / Elévation du PSA après irradiation prostatique : rebond ou récidive biologique?

The fact that external beam radiotherapy and brachytherapy are now considered to be curative techniques has led to major review of the modalities of follow-up after radiotherapy for prostate cancer. The problem concerns both the diagnosis of recurrence, rapidly announced by elevation of prostatic-specific antigen (PSA), usually at a subclinical stage, and the validity of criteria of biochemical recurrence to allow comparison of various study. Physicians involved in follow-up should be aware of the potential of bounce in PSA follow-up after external beam radiotherapy or brachytherapy. The PSA bounce phenomemon was defined by a rise of PSA values (+0.1 -0.8 ng/ml) with a subsequent fall. Biochemical failure after external beam radiotherapy or brachytherapy (with or without hormonotherapy) was defined by Phoenix criteria by a rise of 2 ng/ml above an initial PSA nadir. This definition was more correlated to PSA bounce phenomenon.

Early EUS of the bile duct before endoscopic sphincterotomy for acute biliary pancreatitis.

BACKGROUND: Endoscopic sphincterotomy can benefit patients with suspected biliary pancreatitis, although there are procedure-related complications. EUS can be used to select patients for endoscopic sphincterotomy. The results of this strategy were assessed. METHODS: Information on patients referred for EUS were recorded in a database. One hundred twenty-three patients with suspected biliary pancreatitis (57 men, 66 women; median age 55 years) were included and followed. All underwent EUS followed by endoscopic sphincterotomy during the same procedure if choledocholithiasis was identified. Outcomes were studied in relation to the initial severity of biliary pancreatitis (Ranson and Balthazar scores), presence of stones, and time span between onset of biliary pancreatitis and EUS plus endoscopic sphincterotomy. RESULTS: Thirty-five patients (28%) had a Ranson score greater than 3 on admission and 38 (31%) were Balthazar D-E. The median time from admission to EUS was 3 days. EUS imaging of the bile duct was complete in all but 3 patients. Thirty-three patients (27%) had choledocholithiasis on EUS and underwent endoscopic sphincterotomy. Stones were more frequent in patients with jaundice (p < 0.005) and when EUS was performed less than 3 days after admission (p < 0.05). One hundred patients (81%) recovered without complication. Two patients (1.6%) died, 1 had recurrent BP develop, 6 (5%) had further biliary symptoms, and 16 (13%) had complications of pancreatitis develop (9 pseudocysts). There were 3 mild endoscopic sphincterotomy-related complications (complication rate 6.5%). CONCLUSIONS: In this series in which endoscopic sphincterotomy was performed selectively depending on the endosonographic presence or absence of ductal stones early in the course of the pancreatitis, and not according to its predicted severity, mortality and complications of endoscopic sphincterotomy were low and unrelated to the predicted severity of biliary pancreatitis or the presence of choledocholithiasis. Controlled trials are needed to confirm the superiority of this strategy compared with ERCP alone for the management of biliary pancreatitis.

[Immediate postoperative complications after a laparoscopic partial posterior fundoplication. Early laparoscopic reoperation]. / Complications postopératoires immédiates de la fundoplicature partielle postérieure coelioscopique. Réintervention précoce par coelioscopie.

AIM OF THE STUDY: The immediate postoperative course of laparoscopic partial posterior fundoplication can be complicated by severe dysphagia or paraesophageal hernia. The aim of this study was to describe the technical causes of these complications. PATIENTS AND METHOD: Four patients, operated for gastroesophageal reflux disease by laparoscopic partial posterior fundoplication, developed severe dysphagia (n = 2) or paraesophageal hernia (n = 2) during the immediate postoperative period. A barium swallow examination visualized the complication in both cases of dysphagia and in 1 case of paraesophageal hernia. The correct diagnosis was established by CT scan in the other case of paraesophageal hernia. Reoperations were performed by laparoscopy, 3 days (n = 2) or 6 days (n = 2) postoperatively. RESULTS: Dysphagia was due to compression of the esophagus against the hiatus by the fundoplication. A new and looser fundoplication was easily performed. Dysphagia was no longer present postoperatively. The two patients were symptom-free after 6 and 12 months of follow-up, respectively. In the cases of paraesophageal hernia, the bottoms of the crura were torn. In the patient reoperated 3 days postoperatively, the procedure was easily performed, the postoperative course was uneventful and the patient was symptom-free after a follow-up of 20 months. In the patient reoperated 6 days postoperatively, the upper part of the stomach had moved into the left pleural cavity, the procedure was difficult due to inflammation and thickening of the gastric wall, and the postoperative course was uneventful, but reflux recurred 18 months later. CONCLUSION: When severe dysphagia or paraesophageal hernia occurs during the immediate postoperative course of laparoscopic partial posterior fundoplication, reoperation, possibly by laparoscopy, identifies and cures the technical defects. Based on our experience, we suggest that surgical cure of paraesophageal hernia is easier when performed during the immediate postoperative period.

[Granular cell tumor of the common bile duct. Contribution of endoscopic ultrasonography in 2 cases]. / Tumeurs à cellules granuleuses de la voie biliaire principale. Apport de l'écho-endoscopie dans 2 cas.

We report two cases of granular cell tumors involving the common bile duct in patients presenting with obstructive jaundice. Pre-operative endoscopic ultrasonography showed short asymmetric stricture with small well delimited hypoechoic mass in the distal common bile duct wall and proximal dilatation. These tumors were misdiagnosed as a bile duct carcinoma in one case and biliary metastasis of a melanoma in the other. Histological examination of the resected specimen showed granular cell tumors. A review of the previously reported cases shows that preoperative diagnosis is uncommon. It should be considered when endoscopic ultrasonography performed for biliary obstruction in a young woman shows a small and well limited hypoechoic mass.

Prediction of common bile duct stones by noninvasive tests.

OBJECTIVE: To define accurate and useful predictors of common bile duct stones (CBDS). SUMMARY BACKGROUND DATA: The ability to predict CBDS with noninvasive tests can avoid unnecessary, costly, or risky procedures. METHODS: All patients referred for examination for CBDS by endoscopic ultrasonography (EUS) from 1993-1996 were prospectively entered in a database. In a first sample selected randomly from the whole population, predictors of CBDS were determined by univariate analysis and logistic regression. Predictors were subsequently tested in that sample and in the rest of the population. A separate analysis was done for patients planned for cholecystectomy. RESULTS: Eight hundred and eighty patients (328 men, 552 women), aged 57.8 +/- 17 years (range 16-94), were included. The prevalence of CBDS was 18.8%. Age, serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase (GGT), and alkaline phosphatase, and the existence of jaundice and fever, a dilated bile duct, and a pathologic gallbladder were found to be associated with CBDS. Logistic regression was undertaken separately for patients younger than 70 years (predictors: GGT >7 x normal; pathologic gallbladder; dilated bile duct) and older than 70 years (predictors: GGT >7 x normal; fever > 38 degrees C; dilated bile duct). Odds ratios were 3 to 6.7. The model was satisfactorily applicable to the second sample; age <70 years: chi2 = 3.3 (NS); age >70 years: chi2 = 3.8 (NS). In patients younger than age 70 and planned for cholecystectomy, the combination of the level of GGT and dilated bile duct predicted CBDS accurately. CONCLUSIONS: A simple screening of patients at risk for CBDS can be achieved with three predictive criteria adapted for the patient's age.

[Laparoscopic cholecystectomy and lithiasis of the common bile duct: prospective study on the importance of preoperative endoscopic ultrasonography and endoscopic retrograde cholangiography]. / Cholécystectomie laparoscopique et lithiase de la voie biliaire principale: étude prospective sur l'intérêt de l'écho-endoscopie et de la cholangiographie rétrograde endoscopique préopératoires.

OBJECTIVES: Laparoscopic cholecystectomy is the standard treatment of symptomatic gallstones. At present, no consensus has been reached on the diagnostic and therapeutic methods of concomitant common bile duct stones. Systematic preoperative endoscopic ultrasonography followed, if necessary, by endoscopic retrograde cholangiography and sphincterotomy during the same anesthetic procedure could be a diagnostic and therapeutic alternative for common bile duct stones making possible a laparoscopic cholecystectomy without intraoperative investigation of the common bile duct. METHODS: One hundred and twenty-five patients underwent a prospective endoscopic ultrasonographic evaluation prior to laparoscopic cholecystectomy for symptomatic gallstones. Fourty-four patients (35%) had at least one predictive factor for common bile duct stones. Endoscopic ultrasonography and cholecystectomy were performed on the same day. Endoscopic ultrasonography was followed by endoscopic retrograde cholangiography and sphincterotomy by the same endoscopist in case of common bile duct stones on endoscopic ultrasonography. Patients were routinely followed up between 3 and 6 months and one year after cholecystectomy. RESULTS: Endoscopic ultrasonography suggested common bile duct stones in 21 patients (17%). Endoscopic ultrasonography identified a stone in 17 of 44 patients (38.6%) with predictor of common bile duct stones and only in 4 of 81 patients (4.9%) without predictor of common bile duct stone. Among these 21 patients, one patient was not investigated with endoscopic retrograde cholangiography because of the high risk of sphincterotomy, 19 patients had a stone removed after sphincterotomy, one patient had no visible stone neither on endoscopic retrograde cholangiography, nor on exploration of the common bile duct after sphincterotomy. Endoscopic ultrasonography was normal in 104 patients (83%). However, two patients in this group were investigated with endoscopic retrograde cholangiography because endoscopic ultrasonography was incomplete in one case and because endoscopic ultrasonography was normal in the second case but a stone in the left hepatic duct was detected by ultrasonography. A stone was removed after endoscopic sphincterotomy in these two patients. In the group of 102 patients without stone, 91 out of 92, continued to be asymptomatic during a median follow-up of 8.5 months. One patient with symptoms one month after cholecystectomy underwent endoscopic sphincterotomy but no stone was found. CONCLUSIONS: Systematic preoperative endoscopic ultrasonography followed, if necessary with endoscopic retrograde cholangiography and sphincterotomy is a diagnostic and therapeutic alternative for common bile duct stones making possible a laparoscopic cholecystectomy without intraoperative investigation of the common bile duct for all patients. This alternative is only justifiable in patients with predictor of common bile duct stones.

[W enterocystoplasty with resorbable staples: technic and functional results. Preliminary study]. / Entérocystoplastie en W aux agrafes résorbables: technique et résultats fonctionnels. Etude préliminaire.

INTRODUCTION: The use of absorbable staples for enterocystoplasty allows a marked reduction of the operating time. The long-term results on continence need to be evaluated at result term before adopting this technique. METHODS: Eight patients underwent "W" enterocystoplasty performed with absorbable staples according to the so-called "Detroit" technique, with direct uretero-ileal anastomosis. The continence of these patients was evaluated by clinical follow-up and urodynamic assessment (3 patients). Quality of life was studied by a questionnaire sent to the patient. RESULTS: The mean operating time was 5 hours 20 minutes, the plasty was performed in 25 to 35 minutes. The mean follow-up was 18.7 months, during which two uretero-ileal strictures were diagnosed. 7 of the 8 patients have a good diurnal continence (no leaks) and 1 patient has moderate continence (1 protection). Nocturnal continence was considered to be good in 3 cases, moderate in 2 cases and poor in 3 cases (> 1 protection). Four of the patients evaluated by questionnaire reported urinary disorders. CONCLUSION: The use of absorbable staples allows a definite reduction of the operating time, for a modes excess cost and satisfactory functional results.

Electroconductive lithotripsy: principles, experimental data, and first clinical results of the Sonolith 4000.

The electroconductive lithotripter (ECL) is a new concept for shockwave generation in which a highly conductive solution channels the discharge between the anode and cathode. In vitro experiments showed a linear relation between the voltage setting and the pressure at F2. In vitro stone disintegration studies showed a considerable reduction in shockwave pressure variability, improved energy transfer to the stone, and a unique linear relation between fragmentation and electrode voltage without a saturation effect. This new concept has been used clinically in the Sonolith 4000 lithotripter. In 142 evaluable treatments with a 3-month follow-up, the overall stone-free rate was 82%, and the retreatment rate in stone-free patients was 10%. For stones equal or less than 10 mm, the 3-month stone-free rate, retreatment rate, and secondary procedure rate were 85%, 5%, and 0%, respectively. For stones between 11 and 20 mm, these figures were 83%, 4%, and 2%, respectively. The efficiency quotient was found to be 81% for stones equal or less than 10 mm and 78% for stones between 11 and 20 mm. These clinical results confirm the improvements in efficacy observed in vitro with very satisfactory tolerance.

[Electroconductive lithotripsy: experimental and clinical results with the Sonolith 4000]. / Lithotritie électroconductive: résultats expérimentaux et cliniques du Sonolith 4000.

Electroconductive lithotripsy uses a highly conductive liquid to bathe the electrodes rather than water. The effect is to channel energy between the electrodes and force it to pass directly from the anode to the cathode, exactly at F1. The Sonolith 4000 (Technomed Medical Systems) uses this new generation of "electroconductive" shock waves. Experimental and clinical results are presented. The typical electroconductive technique creates a linear relationship between energy level, in kilovolts, and the amplitude of the acoustic shock at F2 over a wide range of power. There is also a linear relationship between power and effectiveness of desintegration. More than 800 patients have been treated to date. Follow-up has reached 3 months in the 166 treatments reported here. Overall success rate without residual stone was 82%. The percentage of patients with residual stones smaller than 5mm was 5%. The rate of clinical success was 87%. The rate of retreatment in patients without residual stone was 10%. For 11 to 20 mm stones, the success rate (0 fragments), the rate of retreatment and the rate of auxiliary procedures were 83%, 4% and 2% respectively for stones < or = 10 mm and 78% for 11 to 20 mm stones. The electroconductive generator used in this study provided very satisfactory results, better than those generally obtained with classical generators. Tolerance was excellent.

[TULIP: transurethral ultrasound-guided laser-induced prostatectomy. One-year clinical results]. / TULIP: transurethral ultrasound-guided laser-induced prostatectomy. Résultats cliniques à un an.

The TULIP (transurethral ultrasound-guided laser-induced prostatectomy) system combines a real-time ultrasound transducer and a Nd:YAG laser delivery system with a 1.064 microns wavelength within a 22 F urethral probe. The goal is to produce a coagulation necrosis of the prostatic parenchyma, with a subsequent elimination of tissue in the urine. 29 patients have been included in this study, and 13 have a minimal one year follow-up. No complication occurred. 2 patients underwent a transurethral resection of the prostate secondary to the TULIP treatment. All patients complained of irritative urinary symptoms (frequency, burning on urination...) in the days or weeks following the treatment, and suprapubic catheterization tube had to be left in place for a mean duration of 13.8 days. Inclusion/exclusion criteria and evaluation modalities have been the same as in the American national study published elsewhere. At one year, our success rate for at least one criteria has been 84.6%, but only 2 (15%) out of 13 patients have been successful both in symptom score and flow rate.

[TULIP: transurethral ultrasound-guided laser-induced prostatectomy. Clinical results after on year]. / TULIP: transurethral ultrasound-guided laser-induced prostatectomy. Résultats cliniques à un an.

The TULIP (Transurethral Ultrasound-guided Laser-Induced Prostatectomy) system combines a real-time ultrasound transducer and a Nd:YAG laser delivery system with a 1.064 micron wavelength within a 22 F urethral probe. The goal is to produce a coagulation necrosis of the prostatic parenchyma, with a subsequent elimination of tissue in the urine. 29 patients have been included in this study, and 13 have a minimal one year follow-up. No complication occurred. 2 patients underwent a transurethral resection of the prostate secondary to the TULIP treatment. All patients complained of irritative urinary symptoms (frequency, burning on urination...) in the days or weeks following the treatment, and suprapubic catheterization tube had to be left in place for a mean duration of 13.8 days. Inclusion/exclusion criteria and evaluation modalities have been the same as in the American national study published elsewhere. At one year, our success rate for at least one criteria has been 84.6%, but only 2 (15%) out of 13 patients have been successful both in symptom score and flow rate.

Polymorphonuclear count in ascitic fluid after laparotomy in cirrhotic patients.

In order to establish whether an ascitic polymorphonuclear count greater than 250/mm3 remains a diagnostic criterion for postoperative bacterial peritonitis, a prospective study of 16 patients with cirrhosis and ascites undergoing hepatectomy (n = 4), portocaval shunt (n = 5) and biliary and digestive surgery (n = 7) was carried out. Sixty-four consecutive specimens of ascitic fluid were obtained through abdominal one-way suction tubes left in situ. In 17 (26%) specimens, ascitic fluid was blood stained and the polymorphonuclear count was unreliable; none of these specimens demonstrated positive ascitic fluid culture. In the remaining 47 specimens the polymorphonuclear count ranged from 5 to 5,920/mm3. Positive ascitic fluid culture was significantly higher in polymorphonuclear > or = 250/mm3 group (5/13: 38%) than in polymorphonuclear < 250/mm3 group (2/34: 6%) (p < 0.02). These results suggest that, as in non-operated cirrhotic patients: (a) polymorphonuclear count should be taken in account in the diagnosis of postoperative bacterial peritonitis; (b) polymorphonuclear count greater than 250/mm3 is a good criterion for the diagnosis of bacterial postoperative peritonitis.

[Primary carcinoid tumor of the kidney. Apropos of a case with immunohistochemical study]. / Carcinoïde primitif du rein. A propos d'une observation avec étude immunohistochimique.

The authors report a case of primary renal carcinoid in a 57-year-old woman in whom the diagnosis, established by histological findings, was confirmed by argyrophilia and immunohistochemical studies using anti-neuron-specific enolase, chromogranin A, serotonin and somatostatin antibodies. The clinical and pathological features of this rare renal tumor are discussed.