INTRODUCTION: Comorbid substance related disorders are a major health problem for patients in opioid maintenance treatment (OMT). It was investigated whether a reinforcement scheme adapted to the regulatory and financial restrictions of routine treatment reduces concomitant drug use. METHODS: OMT patients from 7 clinics who were using cocaine, benzodiazepines, heroin or amphetamines were randomly allocated to either treatment as usual (n = 64) or treatment with an additional escalating reinforcement scheme (n = 72) in which a patient's number of weekly take-home dosages was increased after 1, 4, 8 and 12 consecutive weeks with drug-free urine specimens. Trial duration was 26 weeks. RESULTS: Completion rates were 64% for controls and 62.5% in the experimental group. Mean number of drug-free weeks was 11.3 (SD 8.5) for the control group and 9.8 (8.9) for the experimental group (p = 0.30). CONCLUSION: The intervention was not effective compared to routine treatment. Additional features might be necessary to achieve an effect, e.g. a higher frequency of urine sampling or use of other reinforcers. It has to be further investigated how interventions which have been proven effective in experimental studies can successfully be adapted to routine care conditions.

Recent high-resolution hydrographic measurements (1976-2001) from the eastern South Pacific (ESP) were employed combined with high-resolution data from the World Ocean Circulation Experiment to evaluate the vertical and horizontal extension of the OMZ (oxygen minimum zone, < 20 µmol kg-1) there. Of the six permanent hypoxic regions in the world oceans, the ESP OMZ is volumetrically the fourth largest, occupying 2.74 x 10(6) km³ and accounting for ~11% globally. Examples of variability in the vertical position of the OMZ in the water-column and also in its intensity offshore central Chile will be addressed. We conclude that the OMZ in the ESP is partly based on old, low-oxygen waters from intermediate depths of the North Pacific Ocean, which were further depleted of oxygen off Mexico and Peru, advected into the region along the eastern Pacific coast. Coastal upwelling zones along the eastern Pacific combined with general circulation thus might provide a mechanism that allows the renewal of upper Pacific Deep Water, the oxygen poorest and oldest water mass of the world oceans.

Datos hidrográficos obtenidos recientemente en el Pacífico Sur oriental (PSO, 1976-2001) se combinaron con datos de alta resolución provenientes del Experimento de Circulación de Océano Mundial (WOCE) para evaluar la extensión vertical y horizontal de la zona mínima de oxígeno (ZMO, <20 µmol kg-1). Las estimaciones de las seis regiones de hipoxia permanente en los océanos mundiales muestran que la ZMO en el PSO, ocupa 2.74 x 10(6) km³ y un ~11% del volumen global representando la cuarta más grande. Esta investigación muestra que la ZMO en el PSO se basa parcialmente de aguas viejas de bajo contenido de oxígeno que provienen de profundidades intermedias del Pacífico del norte, que agotan su oxígeno fuera de las costas de México y Perú y son advectadas dentro de la región a lo largo de la costa del Pacífico oriental. La combinación de las zonas de surgencia costera a lo largo del Pacífico oriental y la circulación general podrían proporcionar un mecanismo que permita la renovación de la parte superior del agua Profunda del Pacifico, las masas de agua más pobres y más vieja de oxígeno disuelto de los océanos mundiales. Se abordarán ejemplos de variabilidad en la vertical de la ZOM en la columna de agua y además su intensidad costa afuera de Chile central.