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Objetivo: Analizar la degradación de los productos metálicos que constituyen las aleaciones de las prótesis de cadera. Pacientes y método: Se midió, mediante absorción atómica, el titanio, el cromo y el cobalto en la sangre de 58 pacientes con prótesis totales de cadera, compuestas por aleaciones de cromo y cobalto y de titanio, con o sin cementar. Se analizó la evolución de las concentraciones séricas preoperatorias, a los seis y a los 12 meses. Resultados: Encontramos una elevación significativa tras el inicio de la movilización de la articulación, pero sin afectación clínica. Los percentiles 95 de la distribución de concentraciones fueron para el Ti 27 mg/L, Cr 1 mg/L y Co 1,7 mg/L. Conclusión: La elevación de estas concentraciones podría ser indicativa de mal funcionamiento del implante o de desgaste excesivo que podría conducir a toxicidades locales o remotas (AU)

Objective: To analyze the degradation of the metal products contained in hip prosthesis alloys. Patients and method: Atomic absorption measurements were made of the titanium, chromium and cobalt concentrations in the blood of 58 patients with total hip replacement implants made of titanium, chromium and cobalt alloys with or without cementing. The evolution of the serum metal concentrations was assessed based on measurements obtained preoperatively and 6 and 12 months after surgery. Results: A significant increase in serum levels was noted after the start of joint mobilization, though without clinical repercussions. The percentile 95 values of the metal concentration distributions were 27 mg/l for titanium, 1 mg/l in the case of chromium, and 1.7 mg/l for cobalt. Conclusion: The rise in serum metal concentrations could be indicative of poor implant function or excessive wear that in turn could lead to local or disseminated toxicity (AU)

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The oxo-transfer catalyst (nitro)(pyridyl)cobalt(III) tetraphenylporphyrin has been reinvestigated by substitution of the distal pyridine ligand with 4-N,N-dimethylaminopyridine and 3,5-dichloropyridine. Differences in their structures and in the reactivity of the compounds toward catalytic secondary oxo transfer were investigated by FT-IR and UV-visible spectroscopy, cyclic voltammetry, X-ray diffraction, semiempirical calculations, and reactions with alkenes in dichloromethane solution. Very modest differences in the hexacoordinate compounds' structures were predicted and observed, but the secondary oxo-transfer reactivity at the nitro ligand varies markedly with the basicity of the pyridine ligand and the position of the coordination equilibrium. Oxo transfer occurs rapidly through the pentacoordinate species (nitro)cobalt(III) tetraphenylporphyrin that is generated by dissociation of the pyridine ligand and therefore is strongly related to the Hammett parameters of these nitrogenous bases. The reactive pentacoordinate species CoTPP(NO(2)) can be generated in solution by addition of lithium perchlorate to (py)CoTPP(NO(2)) by Lewis acid-base interactions or more simply by using the weaker Lewis base Cl(2)py instead of py as the distal ligand. In contrast to pentacoordinate (nitro)iron porphyrins, disproportionation reactions of CoTPP(NO(2)) compound are not evident. This pentacoordinate derivative, CoTPP(NO(2)), is reactive enough to stoichiometrically oxidize allyl bromide in minutes. Preliminary catalytic oxidation reaction studies of alkenes also indicate the involvement of both radical and nonradical oxo-transfer steps in the mechanism, suggesting formation of a peroxynitro intermediate in the reaction of the reduced CoTPP(NO) with O(2).

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We have compared the effects of single oral doses of omeprazole 40 mg, famotidine 40 mg or placebo on gastric secretion in 45 non-obese patients the night before elective biliary surgery. After stable anaesthesia had been established, a Salem orogastric tube was introduced and gastric contents were aspirated by a blinded observer. The volume and pH were noted. After the abdomen was opened aspiration was repeated but on this occasion with the surgeon's manual assistance. We found that the initial aspirate volume underestimated total gastric volume by an average (SD) of 7.1 (6.6) ml. Famotidine, but not omeprazole, produced a significant decrease in gastric volume and acidity. Patients were considered to be at risk if pH < 2.5 and volume > 0.4 ml.kg-1. Three patients in the omeprazole group, three in the placebo group and none in the famotidine group came into this category. We conclude that a single oral dose of omeprazole 40 mg given the night before surgery does not afford adequate prophylaxis for acid aspiration syndrome.

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