Showing papers by "Juan M. Feliu published in 1996"

Structure sensitivity of irreversibly adsorbed tin on gold single-crystal electrodes in acid media

Abstract: Tin adlayers formed on well defined gold electrodes upon irreversible adsorption from SnII solutions have been characterized by means of cyclic voltammetry in sulfuric and perchloric acid solutions. The surface redox reactions undergone by the tin adatom have been found to be structure sensitive. From the analysis of the voltammetric charges involved in these processes it can be suggested that adsorbed tin is oxidized to oxygenated SnII species, which are stable at the electrode surface as long as the electrode potential is kept below 0.25 V. At higher potentials, soluble SnIV species are formed and the adlayer is removed from the electrode surface. The stability of the adlayer is strongly dependent on the solution pH. On Au(111), adsorbed tin is directly oxidized to SnIV species.

Induced adsorption of sulfate/bisulfate anions by submonolayer amounts of copper on deliberately stepped Pt surfaces

Abstract: The presence of submonolayer amounts of underpotentially deposited copper induces the adsorption of sulfate/bisulfate on Pt stepped surfaces. The surfaces studied include the (111) and (110) surfaces and the stepped surfaces of (10,10,9), (554), (332), (221) and (331), which correspond to (111) terrace widths of 19, 9, 5, 3 and 2 atoms, respectively, with monatomic (110) steps. The amount of induced sulfate/bisulfate adsorption increased with decreasing terrace width (increasing step-site density) up to the Pt(221) surface, which has a three-atom wide terrace. In contrast, for the (331) surface, with a two-atom wide terrace, the amount of induced adsorption decreased, suggesting that a three-atom terrace is the minimum width to accommodate the copper adatom and co-adsorbed anion. This type of induced adsorption was not observed for the (111) surface which indicates that the step sites are responsible for the observed behaviour.

Phase II study of cisplatin, 5-fluorouracil, and leucovorin in inoperable squamous cell carcinoma of the esophagus. ONCOPAZ Cooperative Group, Spain.

Abstract: Cisplatin (P) and 5-fluorouracil (5FU) have demonstrated activity for the treatment of squamous cell carcinoma of the esophagus. Previous studies have shown that leucovorin (L) may potentiate the antitumoral activity of 5FU, so we tested the combination P-5FU-L in 31 patients with inoperable squamous cell esophageal carcinoma. Chemotherapy consisted of P 20 mg/m2 in 4 h, followed by L 200 mg/m2 in 2 h and 5FU 600 mg/m2 in 18 h. This schedule was repeated for 5 days every 4 weeks. The treatment plan included three courses of chemotherapy followed by radiotherapy. The overall response rate was 58% (95% CI = 39-76%), with one complete remission (3%), and 61% of patients reported an improvement in dysphagia. Gastrointestinal toxicity was the main side effect: grade 3-4 mucositis appeared in 19% of patients, grade 3-4 nausea/vomiting in 13%, and grade 3-4 diarrhea in 6.5%. There was one toxic death caused by neutropenia and sepsis. Nineteen patients received local radiotherapy after chemotherapy, which increased the overall response rate to 63% (5% complete responses). Dysphagia improved in 75% of them. The median survival for all patients was 11 months. This study shows that sequential therapy with P-5FU-L and radiotherapy achieves a high response rate as well as adequate symptomatic relief in patients with inoperable esophageal cancer. The results justify further evaluation of P-5FU-L in patients with earlier-stage disease.

Cisplatin and UFT Modulated with Leucovorin for the Treatment of Advanced Non-Small-Cell Lung Cancer

Abstract: We performed a phase II study to assess the efficacy and toxicity of the cisplatin-UFT-leucovorin (LV) combination in patients with advanced non-small-cell lung cancer (NSCLC). Twenty-five patients with measurable disease who had not received prior chemotherapy were entered into the trial. The therapeutic regimen consisted of cisplatin 90 mg/m(2) and i.v. LV 500 mg/m(2) on day 1, followed by oral UFT 390 mg/m(2)/day (in two doses on days 1 through 14. Patients also received oral LV 15 mg/12 h on days 2 through 14. Seventeen patients required reduced doses of UFT (200 mg/m(2) due to toxicity. Courses were repeated every 28 days for a minimum of three per patient. Three of 25 patients (12%) achieved a partial response (95% CI: 2.6 to 32.2%), two with 390 mg/m(2)/day and one with 200 mg/m(2)/day of UFT. The main side effects were hematological and gastrointestinal. In the courses including 390 mg/m(2)/day of UFT, grade 3-4 toxicity was leucopenia in 18% of the courses, nausea/vomiting in 27%, and diarrhea and epigastralgia in 13% each. Grade 3-4 toxicities for 200 mg/m(2)/day of UFT were leucopenia 2%, nausea/vomiting 9% and diarrhea 7%. In conclusion, this regimen cannot be recommend for the treatment of advanced NSCLC due to its low response rate and high toxicity.