Reaction of cytochrome P450 with cumene hydroperoxide: ESR spin-trapping evidence for the homolytic scission of the peroxide O-O bond by ferric cytochrome P450 1A2

ESR spin trapping was used to investigate the reaction of rabbit cytochrome P450 (P450) 1A2 with cumene hydroperoxide. Cumene hydroperoxide-derived peroxyl, alkoxyl, and carbon-centered radicals were formed and trapped during the reaction. The relative contributions of each radical adduct to the composite ESR spectrum were influenced by the concentration of the spin trap. Computer simulation of the experimental data obtained at various 5,5-dimethyl-1-pyrroline N-oxide (DMPO) concentrations was used to quantitate the contributions of each radical adduct to the composite ESR spectrum. The alkoxyl radical was the initial radical produced during the reaction. Experiments with 2-methyl-2-nitrosopropane identified the carbon-centered adducts as those of the methyl radical, hydroxymethyl radical, and a secondary carbon-centered radical. The reaction did not require NADPH-cytochrome P450 reductase or NADPH. It is concluded that the reaction involves the initial homolytic scission of the peroxide O-O bond to produce the cumoxyl radical. Methyl radicals were produced from the beta-scission of the cumoxyl radical. The peroxyl adduct was not observed in the absence of molecular oxygen. We conclude that the DMPO peroxyl radical adduct detected in the presence of oxygen was due to the methylperoxyl radical formed by the reaction of the methyl radical with oxygen. At a higher P450 concentration, a protein-derived radical adduct was also detected.     

One or two incisions for nephroureterectomy in transitional cell renal pelvis tumours

A retrospective study comprising 18 patients with transitional cell renal pelvis tumours (TCPT) was carried out to evaluate the results after two different surgical procedures for nephroureterectomy. The kidney was removed by a flank incision and the lower part of the ureter by either an incision in the lower part of the abdomen or intussusception of the ureter followed by transurethral resection of the ureteral orifice. Eight patients were subjected to nephroureterectomy by means of two incisions and another eight patients underwent a simple nephrectomy followed by ureteral intus-susception and transurethral resection. Two patients received other treatments. After nephroureterectomy with a separate incision for ureterectomy, the average hospital stay was 12 days, compared with 7.5 days in patients operated upon with only one abdominal incision. Recurrence of tumour or survival was not significantly different in the two groups.     

Short contact time dissolution of vitrinite and inertinite concentrates

The short contact time dissolution of vitrinite and inertinite concentrates of an Australian bituminous coal was studied under isothermal conditions with tetralin as solvent. The reactivity of the two maceral types and the yields and nature of the products were determined for a range of reaction temperatures (400, 420 and 440 °C) and reaction times (2–20 min). The dissolution of vitrinite proceeded at a significantly greater rate than for inertinite and was associated with greater selectivity to soluble non-gaseous products. At very short reaction times (2 min), the vitrinite underwent solubilizing reactions to yield products of higher molecular weight and greater oxygen functionality than was the case for inertinite, for which changes in the chemical nature of the products were negligible over the range of conditions studied. At longer reaction times (5 min), the composition of the vitrinite-derived products was similar to that of the inertinite-derived products.     

Vibrating Wire Thermometry in Superfluid 3He

We report systematic measurements of the response of a Vibrating Wire Resonator (VWR) in normal and superfluid liquid ³He. Special attention has been paid to the hydrodynamic regime of the superfluid B-phase, where the response parameters of the VWR do not follow a simple law. We show that a simple interpolation between the region where first order slip-corrections can be applied and the ballistic regime is insufficient. Measuring an empirical effective viscosity, we propose a temperature calibration method which allows the use of VWRs as a secondary thermometer at intermediate and high pressures in the temperature range 0.2 T _c < T < 50 mK.     

The transjugular stent implantation for the treatment of malignant portal and hepatic vein obstruction in cancer patients

BACKGROUND: The increase in portal vascular resistance is a significant complication of metastatic disease to the liver or locally advanced cancer, e.g., biliary cancer. PATIENTS AND METHODS: This paper describes the successful palliative treatment of two cancer patients with portal hypertension presenting with the symptoms of tense ascites, mesenteric congestion, and severe variceal bleeding. By creating a stenttract between a hepatic vein and a main branch of the portal vein and/or by placing an extendable stent into the portal vein, the transjugular intrahepatic portosystemic stent-shunt (TIPS) technique was used to decompress the portovascular system. RESULTS: The TIPS-technique offers a new, safe and effective palliation for malignant portal hypertension. In both patients, the symptoms of the portal hypertension disappeared after the procedure. This was accompanied by a significant improvement of the patients performance status allowing an early ambulation. CONCLUSION: Our findings demonstrate the feasibility and effectiveness of the TIPS procedure as a minimal invasive treatment for portal vein decompression in selected tumor patients.     

Solidification Behavior of Undercooled Liquid Aluminum Oxide

Solidification of aluminum oxide from undercooled melts was investigated in containerless experiments. Specimens were levitated in a gas jet, stabilized with an acoustic positioning device, and melted with cw CO₂ laser beams. Cooling curves were obtained by optical pyrometry when the laser intensity was reduced. The materials examined were high-purity Verneuil sapphire, 99.5% polycrystalline alumina, and oxide materials recovered from the effluent of an aluminum-fueled rocket motor. The degree of undercooling, the apparent temperature behavior during the thermal arrest on solidification, and the structure of the materials formed were different in argon and oxygen atmospheres. Undercooling of the sapphire and alumina materials was 360 ± 10 K in an oxygen atmosphere and approximately 450 K in argon. Melting and solidification of high-purity sapphire resulted in a dendritic and porous polycrystalline material in oxygen. Dense, larger crystals were obtained in argon. Products formed from 99.5% alumina were discolored and the cores were white, indicating impurity segregation effects. More reproducible behavior was observed for the sapphire and 99.5% alumina than for the tungstencontaminated rocket motor effluent materials.