El uso de artroscopia no aumenta la incidencia de complicaciones en el manejo de fracturas de mesetas tibiales Schatzker IV-VI / The use of arthroscopy does not increase the incidence of complications in the management of Schatzker IV-VI tibial plateau fractures

Antecedentes y objetivo: El uso de asistencia artroscopica en fracturas de mesetas tibiales tipos I-III según la clasificación de Schatzker se ha popularizado; sin embargo aún existe controversia con respecto a su uso en fracturas Schatzker IV-VI por el potencial riesgo de complicaciones. El objetivo de este trabajo es comparar la tasa de complicaciones intra o postoperatorias entre pacientes con fracturas de mesetas tibiales de este tipo tratados con y sin artroscopia al momento de la reducción y osteosíntesis definitiva. Materiales y métodos: Estudio de cohortes retrospectivo. Se incluyeron pacientes con diagnóstico de fractura de mesetas tibiales Schatzker IV-VI, sometidos a reducción y osteosíntesis definitiva, y al manejo de lesiones asociadas con o sin el uso de artroscopia evaluando la aparición de síndrome compartimental, trombosis venosa profunda e infección relacionada a fractura con seguimiento mínimo de 12 meses posterior a la cirugía definitiva. Resultados: Se incluyeron 288 pacientes: 86 operados con asistencia artroscópica y 202 sin asistencia artroscópica. La tasa de complicaciones total en el grupo con y sin asistencia artroscópica fue del 18,60 y 26,73%, respectivamente (p=0,141). No hubo asociación estadísticamente significativa entre el uso de asistencia artroscópica y el desarrollo de las complicaciones analizadas. Discusión y conclusiones: El uso de artroscopia de rodilla como apoyo de la reducción o como adyuvancia para el tratamiento simultáneo de lesiones intraarticulares concomitantes no aumentó el riesgo de complicaciones en el postoperatorio inmediato ni tras 12 meses de seguimiento.(AU)

Background and objective: The use of arthroscopy for tibial plateau fractures type I, II and III according to Schatzker classification has increased, yet its employment for tibial plateau fractures Schatzker IV, V and VI is controversial due to the potential risk of compartment syndrome, deep vein thrombosis and infection. We aimed to compare the rate of operative and postoperative complications among patients with these types of tibial plateau fractures treated with and without arthroscopy at the time of definitive reduction and osteosynthesis. Methods: Retrospective cohort study. Patients with diagnosis of tibial plateau fracture Schatzker IV, V or VI who underwent reduction and definitive osteosynthesis with or without the use of arthroscopy were included. The development of compartment syndrome, deep vein thrombosis, and fracture-related infection was evaluated up to 12 months after the definitive surgery. Results: Two hundred eighty-eight patients were included: 86 with arthroscopic assistance and 202 without it. The overall complication rate in the group with and without arthroscopic assistance was 18.60% and 26.73%, respectively (P=.141). No statistical association was found between the use of arthroscopic assistance and the development of the analyzed complications. Discussion and conclusion: The use of arthroscopy to support reduction or addressing concomitant intra-articular injuries did not increase the risk of complications in patients with high-energy tibial plateau fractures at 12 months of follow up.(AU)

[Translated article] The use of arthroscopy does not increase the incidence of complications in the management of Schatzker IV–VI tibial plateau fractures / El uso de artroscopia no aumenta la incidencia de complicaciones en el manejo de fracturas de mesetas tibiales Schatzker IV-VI

Antecedentes y objetivo: El uso de asistencia artroscopica en fracturas de mesetas tibiales tipos I-III según la clasificación de Schatzker se ha popularizado; sin embargo aún existe controversia con respecto a su uso en fracturas Schatzker IV-VI por el potencial riesgo de complicaciones. El objetivo de este trabajo es comparar la tasa de complicaciones intra o postoperatorias entre pacientes con fracturas de mesetas tibiales de este tipo tratados con y sin artroscopia al momento de la reducción y osteosíntesis definitiva. Materiales y métodos: Estudio de cohortes retrospectivo. Se incluyeron pacientes con diagnóstico de fractura de mesetas tibiales Schatzker IV-VI, sometidos a reducción y osteosíntesis definitiva, y al manejo de lesiones asociadas con o sin el uso de artroscopia evaluando la aparición de síndrome compartimental, trombosis venosa profunda e infección relacionada a fractura con seguimiento mínimo de 12 meses posterior a la cirugía definitiva. Resultados: Se incluyeron 288 pacientes: 86 operados con asistencia artroscópica y 202 sin asistencia artroscópica. La tasa de complicaciones total en el grupo con y sin asistencia artroscópica fue del 18,60 y 26,73%, respectivamente (p=0,141). No hubo asociación estadísticamente significativa entre el uso de asistencia artroscópica y el desarrollo de las complicaciones analizadas. Discusión y conclusiones: El uso de artroscopia de rodilla como apoyo de la reducción o como adyuvancia para el tratamiento simultáneo de lesiones intraarticulares concomitantes no aumentó el riesgo de complicaciones en el postoperatorio inmediato ni tras 12 meses de seguimiento.(AU)

Background and objective: The use of arthroscopy for tibial plateau fractures type I, II and III according to Schatzker classification has increased, yet its employment for tibial plateau fractures Schatzker IV, V and VI is controversial due to the potential risk of compartment syndrome, deep vein thrombosis and infection. We aimed to compare the rate of operative and postoperative complications among patients with these types of tibial plateau fractures treated with and without arthroscopy at the time of definitive reduction and osteosynthesis. Methods: Retrospective cohort study. Patients with diagnosis of tibial plateau fracture Schatzker IV, V or VI who underwent reduction and definitive osteosynthesis with or without the use of arthroscopy were included. The development of compartment syndrome, deep vein thrombosis, and fracture-related infection was evaluated up to 12 months after the definitive surgery. Results: Two hundred eighty-eight patients were included: 86 with arthroscopic assistance and 202 without it. The overall complication rate in the group with and without arthroscopic assistance was 18.60% and 26.73%, respectively (P=.141). No statistical association was found between the use of arthroscopic assistance and the development of the analyzed complications. Discussion and conclusion: The use of arthroscopy to support reduction or addressing concomitant intra-articular injuries did not increase the risk of complications in patients with high-energy tibial plateau fractures at 12 months of follow up.(AU)

[Translated article] The use of arthroscopy does not increase the incidence of complications in the management of Schatzker IV-VI tibial plateau fractures.

BACKGROUND AND OBJECTIVE: The use of arthroscopy for tibial plateau fractures type I, II and III according to Schatzker classification has increased, yet its employment for tibial plateau fractures Schatzker IV, V and VI is controversial due to the potential risk of compartment syndrome, deep vein thrombosis and infection. We aimed to compare the rate of operative and postoperative complications among patients with these types of tibial plateau fractures treated with and without arthroscopy at the time of definitive reduction and osteosynthesis. METHODS: Retrospective cohort study. Patients with diagnosis of tibial plateau fracture Schatzker IV, V or VI who underwent reduction and definitive osteosynthesis with or without the use of arthroscopy were included. The development of compartment syndrome, deep vein thrombosis, and fracture-related infection was evaluated up to 12 months after the definitive surgery. RESULTS: Two hundred eighty-eight patients were included: 86 with arthroscopic assistance and 202 without it. The overall complication rate in the group with and without arthroscopic assistance was 18.60% and 26.73%, respectively (p=.141). No statistical association was found between the use of arthroscopic assistance and the development of the analysed complications. DISCUSSION AND CONCLUSION: The use of arthroscopy to support reduction or addressing concomitant intra-articular injuries did not increase the risk of complications in patients with high-energy tibial plateau fractures at 12 months of follow up.

The use of arthroscopy does not increase the incidence of complications in the management of Schatzker IV-VI tibial plateau fractures. / El uso de artroscopia no aumenta la incidencia de complicaciones en el manejo de fracturas de mesetas tibiales Schatzker IV-VI.

BACKGROUND AND OBJECTIVE: The use of arthroscopy for tibial plateau fractures type I, II and III according to Schatzker classification has increased, yet its employment for tibial plateau fractures Schatzker IV, V and VI is controversial due to the potential risk of compartment syndrome, deep vein thrombosis and infection. We aimed to compare the rate of operative and postoperative complications among patients with these types of tibial plateau fractures treated with and without arthroscopy at the time of definitive reduction and osteosynthesis. METHODS: Retrospective cohort study. Patients with diagnosis of tibial plateau fracture Schatzker IV, V or VI who underwent reduction and definitive osteosynthesis with or without the use of arthroscopy were included. The development of compartment syndrome, deep vein thrombosis, and fracture-related infection was evaluated up to 12 months after the definitive surgery. RESULTS: Two hundred eighty-eight patients were included: 86 with arthroscopic assistance and 202 without it. The overall complication rate in the group with and without arthroscopic assistance was 18.60% and 26.73%, respectively (P=.141). No statistical association was found between the use of arthroscopic assistance and the development of the analyzed complications. DISCUSSION AND CONCLUSION: The use of arthroscopy to support reduction or addressing concomitant intra-articular injuries did not increase the risk of complications in patients with high-energy tibial plateau fractures at 12 months of follow up.

Use of isolated cyclohexanone monooxygenase from recombinant Escherichia coli as a biocatalyst for Baeyer-Villiger and sulfide oxidations.

The performance, in Baeyer-Villiger and heteroatom oxidations, of a partially purified preparation of cyclohexanone monooxygenase obtained from an Escherichia coli strain in which the gene of the enzyme was cloned and overexpressed was investigated. As model reactions, the oxidations of racemic bicyclo[3.2.0]hept-2-en-6-one into two regioisomeric lactones and of methyl phenyl sulphide into the corresponding (R)-sulphoxide were used. Enzyme stability and reuse, substrate and product inhibition, product removal, and cofactor recycling were evaluated. Of the various NADPH regeneration systems tested, 2-propanol/alcohol dehydrogenase from Thermoanerobium brockii appeared the most suitable because of the low cost of the second substrate and the high regeneration rate. Concerning enzyme stability, kosmotropic salts were the only additives able to improve it (e.g., half-life from 1 day in diluted buffer to 1 week in 1 M sodium sulphate) but only under storage conditions. Instead, significant stabilization under working conditions was obtained by immobilization on Eupergit C (half-life approximately 2.5 days), a procedure that made it possible to reuse the catalyst up to 16 times with complete substrate (5 g x L(-1)) conversion at each cycle. Reuse of free enzyme was also achieved in a membrane reactor but with lower efficiency. Water-organic solvent biphasic systems, which would overcome substrate inhibition and remove from the aqueous phase, where reaction takes place, the formed product, were unsuccessful because of their destabilizing effect on cyclohexanone monooxygenase. More satisfactory was continuous substrate feeding, which shortened reaction times and, very importantly, yielded in the case of bicyclo[3.2.0]hept-2-en-6-one (10 g x L(-1)) both lactone products with high optical purity (enantiomeric excess > or = 96%), which was not the case when all of the substrate was added in a single batch.

Enantioselective synthesis of tert-butyl tert-butanethiosulfinate catalyzed by cyclohexanone monooxygenase.

Cyclohexanone monooxygenase from Acinetobacter calcoaceticus catalyzes the asymmetric oxidation of tert-butyl disulfide to enantiomerically pure (R)-tert-butyl tert-butanethiosulfinate. Lower enantioselectivities and conversions were observed in the oxidation of i-propyl, n-butyl, p-tolyl tert-butyl disulfides and alkylthiophosphonates.

Recent biotechnological developments in the use of peroxidases.

Peroxidases are ubiquitous oxidoreductases that use hydrogen peroxide or alkyl peroxides as oxidants. Advances have recently been made in using them to prepare, under mild and controlled conditions, chiral organic molecules that are valuable for the chemoenzymatic synthesis of a wide range of useful compounds. Horseradish peroxidase can be converted into a peroxygenative enzyme by molecular engineering. Chloroperoxidase, the most versatile peroxidase, behaves like a 'true' monooxygenase in sulfoxidations with molecular oxygen and an external reductant, with substantial increases in enantioselectivity and enzyme stability.

Chloroperoxidase-catalyzed enantioselective oxidation of methyl phenyl sulfide with dihydroxyfumaric acid/oxygen or ascorbic acid/oxygen as oxidants.

The chloroperoxidase catalyzed oxidation of methyl phenyl sulfide to (R)-methyl phenyl sulfoxide was investigated, both in batch and membrane reactors, using as oxidant H2O2, or O2 in the presence of either dihydroxyfumaric acid or ascorbic acid. The effects of pH and nature and concentration of the oxidants on the selectivity, stability, and productivity of the enzyme were evaluated. The highest selectivity was displayed by ascorbic acid/O2, even though the activity of chloroperoxidase with this system was lower than that obtained with the others. When the reaction was carried out in a membrane reactor, it was possible to reuse the enzyme for several conversion cycles. The results obtained with ascorbic acid/O2 and dihydroxyfumaric acid/O2 as oxidants do not seem to be compatible with either a mechanism involving hydroxyl radicals as the active species or with the hypothesis that oxidation occurs through the initial formation of H2O2. Copyright 1999 John Wiley & Sons, Inc.

Sulphoxidation reaction catalysed by myeloperoxidase from human leucocytes.

The oxidation of alkyl aryl sulphides by myeloperoxidase (MPO) at the expense of hydrogen peroxide was investigated under steady-state conditions. The sulphide concentration effect was studied under saturating H2O2 concentrations at pH 5.0 and 20 degreesC. The kinetic constants, kcat and Km, of the different substrates were determined and the values were in the 1-10 s-1 range and around 43+/-26 microM respectively, whatever the sulphide considered. In the case of p-substituted thioanisoles, the oxidation rate was dependent upon the substituent effect. The correlation of log(kcat) with the substituent constants (sigma+ values) (Hammett equation) could be explained by a reaction mechanism involving the enzyme compound II and a sulphenium radical cation. This conclusion was also supported by spectrophotometric analysis of catalytic intermediates of the enzyme, showing the accumulation of compound II. Moreover, chiral HPLC analyses showed that MPO oxidation of alkyl aryl sulphides produced the corresponding (R)-sulphoxides with a low enantioselectivity (4-8%). Chloride ion effects on the MPO-catalysed oxygenation of sulphides were also studied. Chloride acted as a substrate for MPO and as an activator in MPO-catalysed sulphoxidation. Inhibition occurred at chloride concentrations above 120 mM, whereas below 120 mM, chloride increased the reaction rate when using p-tolyl methyl sulphide as the substrate. In the presence of 100 mM chloride the catalytic efficiency (kcat/Km) of MPO increased 3-4-fold, whatever the sulphide considered, but racemic products were obtained. These data have been interpreted in the light of known structural information on the accessibility of the distal haem cavity.

Effects of chloride on the kinetics and stereochemistry of chloroperoxidase catalyzed oxidation of sulfides.

At pH 3, chloride dramatically influenced both the Km of chloroperoxidase (CPO) for methyl p-tolyl sulfide, which decreased, and its activity, which increased. The Km value changed from 75 microM in the absence of chloride to < or = 1.2 microM in > or = 0.9 mM chloride, and the kcat from 53 s-1 in 0 to 1750 s-1 in 50 mM halide. The kcat/Km value at 0.9 mM chloride was 414 microM -1s-1 compared to 0.7 microM-1s-1 in the absence of the halide. At pH 5, the activating effect was less pronounced. Chloride also acted as inhibitor versus hydrogen peroxide. The data are consistent with a reaction mechanism in which, on hand, chloride competes with hydrogen peroxide for the native enzyme and, on the other hand, activates sulfide oxidation by binding to CPO Compound I to give a CPO-chlorinating intermediate (EOCl-). However, contrary to what happened in the absence of chloride, where the oxidation was enantioselective and an oxygen atom of H2O2 was incorporated in the sulfoxide (from experiments with 18O-labeled H2O2), in the presence of the halide the oxidation was not enantioselective and there was no incorporation of oxygen from H2O2. The data suggest that sulfide oxidation takes place through an enzyme-generated freely dissociable oxidized halogen intermediate formed by the interaction of EOCl- with Cl-.

Oxidation of cysteine to cysteic acid in proteins by peroxyacids, as monitored by immobilized pH gradients.

It has often been debated whether the presence of persulfate in a polyacrylamide gel could lead to the oxidation of cysteine (Cys) in proteins to cysteic acid. In fact, direct incubation of bovine serum albumin (BSA) with peroxodisulfate and periodate barely alters the isoelectric point (pI) and does not produce any cysteic acid. In contrast, caroate (peroxomonosulfate) and perphthalate strongly lower the pI of BSA. In the former case it as demonstrated that 4-Cys (of a total of 35) were converted into cysteic acid. Perphthalate was found to be, by far, the strongest oxidant: 15 (of 35) Cys residues were oxidized to cysteic acid and all methionine groups were destroyed.

Enantioselective oxidations of sulfides catalyzed by chloroperoxidase.

The chloroperoxidase-catalyzed and horseradish peroxidase catalyzed oxidations of sulfides by tert-butyl and other peroxides have been investigated. The former metal enzyme afforded the corresponding sulfoxides having R absolute configuration in up to 92% enantiomeric excess (ee), whereas the latter gave racemic products. The various factors that control the enantioselectivity of the oxygenation have been examined.