Mechanism and dynamics of fatty acid photodecarboxylase.

Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.

Early biliary pseudolithiasis during ceftriaxone therapy for acute pyelonephritis in children: a prospective study in 34 children.

The prolonged biological half-life of Ceftriaxone, allowing once-daily dosing, has contributed to the large diffusion of this third-generation cephalosporin in children. Ceftriaxone is known to induce reversible precipitates in the gallbladder of adults and children. A prospective study was conducted during 1997 in 34 children admitted for the treatment of acute pyelonephritis. Ceftriaxone (intravenous daily single-dose of 50 mg/kg under 2g/day) was initially used. A first gallbladder sonogram, performed before the first or second injection, was normal in all cases. A second evaluation was performed before the fifth and last injection. On this second evaluation the presence of one (n = 3) or two gallstones was recorded in 5 children (15%) on a sonogram made after 3 (n = 4) or 5 (n = 1) injections. Their median age was 7 years (range 4 months to 11 years). All five children remained symptom-free and the normalization of the sonographic patterns was constant on the last sonogram performed 2 (n = 1), 3 (n = 2) and 5 months (n = 2) after discontinuation of Ceftriaxone. This study confirms the possibility of precocious biliary lithiasis under Ceftriaxone therapy in childhood and their spontaneous dissolution after discontinuation of the drug. They seem unpredictable and independent of the age, sex in a cohort homogeneous for the nature of the infection, modality of a short- and low-dose therapy. Clinicians and radiologists should be aware of this complication as an etiology of a so-called primary cholelithiasis and to prevent anxiety or unnecessary cholecystectomy. The antibacterial and pharmacokinetic benefits of Ceftriaxone outweigh the problem of reversible biliary pseudolithiasis with this drug.

[Prognostic value of x-ray computed tomography in acute pancreatitis: contribution of the injection of intravenous contrast media]. / Valeur pronostique de la tomodensitométrie dans les pancréatites aiguës: apport de l'injection de produit de contraste intraveineux.

Thirty seven patients suffering from acute pancreatitis were explored using contrast-enhanced computed tomography (CT). The authors found a good concordance between the extension of the lesions on the initial CT examination, prognostic criteria on admission and the course of the disease. In addition, a new prognostic CT sign was reported in the early phase of parenchymal contrast perfusion, i.e. the lack of contrast-enhancement in a limited portion of the pancreas. This sign was present in 8 patients, all with severe clinical symptoms. These 8 patients showed the highest morbidity rate in the series with abscess-type complications occurring in all, compared with 24 p. 100 among the 29 other patients who did not exhibit this CT sign. Moreover, these 8 patients showed the highest mortality rate (25 p. 100 compared with 3.5 p. 100 among the other patients). An histological analysis of partial pancreatectomy specimens was performed in 7 out of the 8 patients. Devitalized pancreatic tissue, at the site of the parenchymal abnormalities on CT scan, was found in all cases. One false negative case was reported. Contrast-enhanced CT scan seems to be the most reliable method for diagnosing pancreatic necrosis during acute severe pancreatitis. It appears to be an useful prognostic predictor of morbidity. It can improve the outcome of the disease by depicting and guiding needle aspiration of a fluid collection, and/or surgery in case of clinical findings suggesting abscess formation.

[Sensitivity of fine-needle puncture-biopsy in the histologic diagnosis of hepatic and pancreatic malignant tumors]. / Sensibilité de la ponction-biopsie à l'aiguille fine dans le diagnostic histologique des tumeurs malignes hépatiques et pancréatiques.

Aspiration-biopsies under ultrasound guidance, using a fine needle (external diameter inferior to 1 mm) have been performed in 61 malignant hepatic tumors (group I) and 25 pancreatic carcinomas (group II). Malignancy was diagnosed in 83 p. 100 cases; in group I, the sensitivity is 87 p. 100; the difference between hepatocellular carcinoma and liver metastases could be made in 88 p. 100 cases and in case of metastases, the site of the primitive carcinoma could be suggested in 77 p. 100 cases. In group II, the sensitivity is 72 p. 100. No complications were noted.

[Echography of tumors with multiple localizations in the urinary tract. Apropos of 2 cases]. / Echographie des tumeurs à localisations multiples de la voie urinaire excrétrice. A propos de deux observations.

The authors report 2 cases of unilateral non functioning hydronephrotic kidney, associated with homolateral bladder tumoral filling defect. Cystoscopy and histology showed a non infiltrating tumor. In one case, sonography showed a diffuse tumoral proliferation from the renal pelvis to the bladder and in the other case revealed a tumor located in the lower ureter prolapsed into the bladder. Both were non infiltrating ureteral tumors on histologic examination. These sonographic features, suggesting that the level of obstruction was not the bladder, accounted for the contradiction between urographic findings and lack of histological infiltration.

[Real time echographic study of the normal Wirsung duct. Comparison with retrograde catheterization]. / Etude du canal de Wirsung normal en échographie temps réel. Confrontation avec le cathétérisme rétrograde.

An ultrasonogram (US) of the pancreatic duct was performed in 59 patients prior to a retrograde pancreatography (ERCP). In 41 patients with normal ERCP, the pancreatic duct in the body of the pancreas was found to be on US less than 2 mm. The diameter measured on ERCP on the same portion of the pancreas was found to be 2,5 larger. On 18 abnormal ERCP, 3 patients had normal US defined by a pancreatic duct less than 2 mm in internal diameter and a normal pancreatic parenchyma. These 3 patients had mild ductal abnormalities of chronic pancreatitis on ERCP, undetectable by US. These 3 false negative cases give to a normal pancreatic US a negative predictive value of 93%. The injection of 5 normal autopsy pancreas, combined with US of the pancreatic duct, showed that neither the radiological magnification nor the pressure of injection accounted for the discrepancy between US and ERCP in the measurement of the pancreatic duct diameter. It is thought to be due to an underestimation of the internal diameter of the duct which may be related to an apparent thickening of its highly echogenic walls.

[Isolated tuberculous involvement of a posterior vertebral arch. Value of x-ray computed tomography and puncture under ultrasonography for the diagnosis. Apropos of a case]. / Atteinte tuberculeuse isolée d'un arc vertébral postérieur. Intérêt de la tomodensitométrie et de la ponction sous échographie pour le diagnostic. A propos d'un cas.

A case relative to an isolated tuberculous lesion of a vertebral arch associated with a paravertebral abscess is reported. The authors insist on the rarity of this location. They underline the role of the computed tomography for the positive diagnosis and the precise extent of lesions and the interest of the biopsy under ultrasonography for the bacteriological and histological diagnosis.

[Abdominal echography in the diagnosis and monitoring of retroperitoneal fibrosis. Apropos of 2 cases]. / Echographie abdominale dans le diagnostic et la surveillance des fibroses rétropéritonéales. A propos de 2 observations.

The authors report 2 new cases of unilateral ureteral obstruction due to a retroperitoneal fibrosis diagnosed by ultrasound examination. Retroperitoneal fibrosis presents as a hypo-echogenic, homogeneous mass, anterior to the sacral promontary, extending more or less cranially or caudally around the aorta and the iliac vessels where it gets a circumferential appearance. The complete regression of the mass has been followed by ultrasound on one patient. The authors underline the diagnostic problem posed with the R.P.F. secondary to metastatic neoplasm and discuss the place of ultrasound guided fine needle biopsy performed on one patient for the diagnosis of the affection.

[Spontaneous rupture of a neurogenic bladder. Report of a new case]. / Rupture spontanée d'une vessie neurologique. Présentation d'un nouveau cas.

The authors report a new case of intra-peritoneal spontaneous rupture of the bladder, which was observed during a voiding urethro-cystography. Urodynamic studies on this patient showed a neurologic bladder which was due to a diabetic neuropathy.

[Real-time echography of the parathyroid glands]. / Echographie en temps réel des glandes parathyroïdes.

Real time ultrasonography of the neck, using a sectorial scanner with an ordinary 5 MHz transducer, was performed on 24 patients with hypercalcemia. 21 of them were suffering from primary hyperparathyroidism and 3 from a severe paraneoplasic hypercalcemia. There were 18 true positive, 3 false positive, 1 false negative and 2 true negative. The sensibility and the negative predictive value of the method are 83%. The specificity and the negative predictive value are 95%. The accuracy is 91%. Real time ultrasonography of parathyroid glands is possible with a sectorial scanner using an ordinary 5 MHz transducer and is systematically done, in our institution, before cervicotomy.

[Complications of the treatment of renal calculi by extracorporeal lithotripsy. Prospective evaluation of 80 treated kidneys]. / Complications du traitement de la lithiase rénale par lithotriptie extracorporelle. Evaluation prospective de 80 reins traités.

The acute effects of extracorporeal shock wave lithotripsy (ESWL) on morphology and function of the kidney were prospectively evaluated by abdominal radiography, ultrasonography and contrast-enhanced computed tomography, in 80 treated kidneys. Two types of complications were demonstrated: 1. Obstruction of the ureter by stone fragments in 25% of cases. Relief procedures became necessary in 5 patients (6% of the 80 cases). 2. Limited injuries of the kidney and perirenal spaces in 44% of cases: parenchymatous abnormalities 17.5%; subcapsular hematoma 12.5%; perirenal fluid collection 24%. No treatment was necessary and morphologic abnormalities disappeared in one or two months post-ESWL. Severe ureteral obstruction after ESWL seems to be related to stone size. No definitive evidence that kidney's injury was related to the number of shock waves applied to the kidney was found.

[X-ray computed tomography in the course of mediastinitis after sternostomy for heart surgery]. / Apport de la tomodensitométrie dans l'évolution des médiastinites après sternotomie pour chirurgie cardiaque.

Results are reported of a prospective study of 79 CT scan examinations in 50 patients who had undergone sternotomy for cardiovascular surgery. In 69 cases the examination was conducted during the course of a progressive postoperative mediastinitis treated surgically. Mediastinitis was confirmed in 13 cases, including 12 relapses. In 2 cases the CT scan image was normal (2 false negatives) whereas mediastinal drains had been inserted. The CT scan image of mediastinitis shows mainly hypodense fluid collections (0 to 16 UH) in anterior mediastinum or between sternotomy borders (8 of 13 cases). But this type of image, detected 11 times in the absence of recurrence (favorable course), can result from a residual serous collection after ablation of drains. In 8 cases, a CT scan-guided puncture (7 cases) or one under ultrasound control (1 case) eliminated recurrence. The CT scan imaging also allowed diagnosis of 5 cases of osteitis, confirmed surgically. These findings indicate the definite interest of CT scan imaging in postoperative follow-up review of median sternotomies. It appears to be particularly indispensable for surveillance of surgically treated mediastinitis, because of the serious consequences of relapses and the often clinically silent chronic bone lesion. However, the possibility of residual serous collections emphasizes the importance of the clinical context and should lead to guided puncture investigation in doubtful cases.

[Muscle metastases: ultrasonic and x-ray computerized tomographic aspects. Apropos of 9 cases]. / Les métastases musculaires: aspects échographiques et tomodensitométriques. A propos de 9 observations.

Clinical, ultrasound and CT scan examinations were carried out in 9 patients with secondary muscle lesions. All muscles can be affected but there was a marked predominance of psoas lesions (6 of the 9 cases). Two contrasting clinical pictures are seen. Secondary muscle tumors can occur during evolution of a known treated cancer (5 of the 9 cases), revealed usually by large, rarely painful, mass. CT scan imaging shows a heterogeneous mass taking up contrast and often partially necrotic, the lesions appearing hypoechogenic or heterogeneous on ultrasound examination. Certain lesions can be totally necrotic. In some cases (4 of the 9 patients) the muscle metastases revealed the presence of a tumor. Symptomatology may be atypical and lead to a delay in diagnosis. Fine needle puncture biopsy can detect the secondary origin of the muscle lesion and also the primary tumor site (4 out of 9 cases), bronchopulmonary and colon cancer predominating. Images are however non-specific and in the absence of NMR imaging the muscle or lymph node metastases can be confused, although this has no practice consequences since treatment is identical.

[Osseous hydatidosis of the pelvic girdle. Contribution of computerized tomography and ultrasonics. Apropos of 3 cases]. / Hydatidose osseuse de la ceinture pelvienne. Apport de la tomodensitométrie et de l'échographie. A propos de 3 observations.

Three cases of bone hydatidosis of pelvis with invasion of soft tissues provided data on the effectiveness of CT scan and ultrasound imaging for diagnosis, evaluation of extension and follow up surveillance of this affection. Two of the three patients treated medically were followed up by review CT scan and ultrasound examinations. The two techniques were found to be effective for detecting recurrence and for surveillance of hydatid lesions of soft tissues during medical therapy.

[Value of ultrasonography in the diagnosis of carcinoma of Vater's ampulla. Apropos of 9 cases]. / Intérêt de l'échographie dans le diagnostic des ampullomes vatériens. A propos de 9 cas.

In ten patients where ampullary carcinoma was proved, ultrasonography has been performed in 9 cases and failed in 1 case. The results reported, could be put into two different groups. In 7 cases out of 9, sonogram did not show any specific signs: In 3 of these cases, it mimicked a pancreatic carcinoma; in the other 4 cases, dilatation of biliary and/or pancreatic ducts has only been evaluated. In the 2 remaining cases (20% of the 10 patients of the series) the diagnosis of ampullary carcinoma could be suggested on sonographic features. It showed the "double duct sign" and a bulging mass filling the lumen of the distal common bile duct. In one of these 2 cases, the mass was also detectable in the second duodenum, previously filled with water. Endoscopy with biopsy is the most reliable procedure in the diagnosis of ampullary carcinoma but the interest of ultrasonography is: 1 degree to show suggestive findings when the tumor bulges in the common bile duct and the duodenum; 2 degrees to evaluate the tumor extension in the pancreatic parenchyma.

[Real-time echography in the evaluation of the venous extension of cancer of the kidney. Prospective study of 50 cases]. / L'échographie temps réel dans le bilan d'extension veineuse des cancers du rein. Etude prospective sur cinquante cas.

Fifty patients with renal carcinoma were evaluated with real time ultrasonography: 15 tumors involved the renal vein (group Ia), 12 of them presented with caval tumor extension (group Ib); 35 tumors did not involve the renal veins (group II). In 3 cases, the renal vein could not be visualized. If the renal veins could be adequately delineated, evaluation of venous extension could be achieved in 100% cases (groups Ia and II). Nevertheless, caval tumor extension could be detected in only 70% cases (group Ib). This prospective study suggests that in the case of renal vein free of thrombus on ultrasonography, further investigations are not necessary to evaluate the venous extension of renal carcinoma. In case of inadequate delineation, or tumor involvement of the renal vein on ultrasonography, evaluation of inferior vena cava is mandatory, either by computed tomography, or inferior cavography.

[Endoscopically "impassable" urethral stenosis. Catheterization under fluoroscopic guidance. Apropos of 11 cases]. / Sténoses de l'urètre "infranchissables" par voie endoscopique. Cathétérisme sous guidage radioscopique. A propos de onze cas.

In eleven patients with impassable urethral stenoses, we attempted retrograde catheterisation with an angiographic guide under fluoroscopic control. The stenosis was able to be negotiated with the guide in 10 cases (91% success). After dilatation by dilators (coaxial or rigid) or by Olbert's angioplasty balloon, we were able to introduce a Foley catheter into the bladder. The only failure was caused by a very marked separation of the two ends of the urethra due to trauma. This simple and effective method constitutes an alternative to immediate surgical treatment of endoscopically impassable urethral stenoses.

[Idiopathic spontaneous adrenal hematoma in adults: echography and x-ray computed tomography. Apropos of 5 cases]. / Hématome surrénalien spontané idiopathique de l'adulte: aspects échographiques et tomodensitométriques. A propos de cinq observations.

The five patients presented with sudden lumbar pain, transient collapse, and a right hypochondrium palpable mass. The location and the type of the mass could be determined by ultrasonography which showed a septated heterogenous mass displacing the retroperitoneal fat anteriorly. Computed tomography showed in two cases tiny parietal calcifications and a spontaneous hyperdensity in one case. All the patients underwent surgery and no tumoral tissue could be found.

[X-ray computed tomography in acute pancreatitis]. / La tomodensitométrie dans les pancréatites aiguës.

Diagnostic imaging of acute pancreatitis has been revolutionized by the introduction of computed tomography (CT). The purpose of this report is to review the different CT findings of the disease. The authors emphasize the predictive value of the contrast enhanced CT. It seems to be the most reliable method for detecting the most severe forms of acute pancreatitis and their complications. Correlation of CT findings with clinical and biological prognostic signs allows an easier surgical management.