Open ISEmeter: An open hardware high-impedance interface for potentiometric detection.

In this work, a new open hardware interface based on Arduino to read electromotive force (emf) from potentiometric detectors is presented. The interface has been fully designed with the open code philosophy and all documentation will be accessible on web. The paper describes a comprehensive project including the electronic design, the firmware loaded on Arduino, and the Java-coded graphical user interface to load data in a computer (PC or Mac) for processing. The prototype was tested by measuring the calibration curve of a detector. As detection element, an active poly(vinyl chloride)-based membrane was used, doped with cetyltrimethylammonium dodecylsulphate (CTA(+)-DS(-)). The experimental measures of emf indicate Nernstian behaviour with the CTA(+) content of test solutions, as it was described in the literature, proving the validity of the developed prototype. A comparative analysis of performance was made by using the same chemical detector but changing the measurement instrumentation.

The use of digital simulation to improve the cyclic voltammetric determination of rate constants for homogeneous chemical reactions following charge transfers.

Cyclic voltammetry (CV) is a very useful electrochemical tool used to study reaction systems that include chemical steps that are coupled to electron transfers. This type of system generally involves the chemical reaction of an electrochemically generated free radical. Published methods exist that are used to determine the kinetics of electrochemically initiated chemical reactions from the measurements of the peak current ratio (i(pa)/i(pc)) of a cyclic voltammogram. The published method requires working curves to relate a kinetic parameter to the peak current ratio. In the presented work, a digital simulation package was used to obtain improved working curves for specific working conditions. The curves were compared with the published results for the first- and second-order chemical reactions following the charge transfer step mechanisms. According to the presented results, the previously published working curve is reliable for a mechanism with a first-order chemical reaction; however, a change in the switching potential requires a recalculation of the curve. In the case of mechanisms with a second-order step (dimerisation and disproportionation), several different views exist on how the second-order chemical term should be expressed so that different values of the constant are obtained. Parameters such as electrode type, electrode area, electroactive species concentration, switching potential, scan rate and method for peak current ratio calculation modify the working curves and must always be specified. We propose a standardised method to obtain the most reliable kinetic constant values. The results of this work will permit researchers who handle simulation software to construct their own working curves. Additionally, those who do not have the simulation software could use the working curves described here. The revelations of the presented experiments may be useful to a broad chemistry audience because this study presents a simple and low-cost procedure for the study of free radicals that otherwise should be studied with more sophisticated and expensive techniques, such as ESR or pulse radiolysis.

Development of high-frequency true-linear generator for electrochemical purposes.

A new design for a true-linear generator suitable for electrochemical measures is presented. The main component of generation system is an MAX038 chip, a high-frequency relaxation-type oscillator. The design is completed with a digital interface for computer control and an output stage to make signal suitable for cyclic voltammetry experiments. A digital circuit is also included to obtain single sweep signals by isolating one period or a half-period from continuous original output. Performance of presented generator is tested up to 1 MV s(-1) obtaining good stability and linearity.

Characterization and regulation of a CHO cell line stably expressing human serotonin N-acetyltransferase (EC 2.3.1.87).

Current melatonin research is essentially based on the finding of new molecular tools, including synthetic or natural agonists and antagonists for the melatonin receptors and synthetic inhibitors of the enzymes involved in its biosynthesis. Indeed, the use of these compounds will improve our understanding of some of the numerous mechanisms of action of melatonin. The present report deals with the establishment and description of a new cell line expressing in a stable manner human arylalkylamine-N-acetyltransferase (AANAT, E.C.2.3.1.87). This new cellular system permits one to check the capacity of newly discovered inhibitors to penetrate the cell and reach their target. Some emphasis is put on inhibitors of the bromoacetyltryptamine family since these precursor compounds form in situ bisubstrate inhibitors with strong affinity for the human enzyme. AANAT is known to undergo complex and rapid regulation by a subtle balance between extremely fast catabolism and protection against it, both due to serine phosphorylation. In the present report, this phosphorylation is shown to occur in vitro after incubation with several kinases (rho-kinase, chk-1, protein kinase A) but not with protein kinase C. Phosphorylation enhances the specific activity of the enzyme by a factor of two to five. This phosphorylation is also shown to occur after treatment of the cell with compounds such as forskolin and rolipram that enhance or protect the intracellular pool of cAMP or the cell-permeable cAMP analogue, dioctanoyl-cAMP. The specificity of the cellular model was assessed using a series of substrates and inhibitors of AANAT already described in the literature, and the characteristics of this cellular system are shown to correspond with those reported for the purified enzyme. This cell line was used to screen libraries of compounds in a living system and led to the discovery of several potent specific and non-toxic AANAT inhibitors.

[The Ottawa ankle guidelines: analysis of their validity as clinical decision guidelines in the indication of X-rays for ankle and/or middle-foot injuries]. / Reglas del tobillo de Ottawa: análisis de su validez como reglas de decisión clínica en la indicación de radiografías en los traumatismos de tobillo y/o medio pie.

OBJECTIVE: To analyse the validity of the Ottawa ankle guidelines (OAG) as clinical decision guidelines in the indications of X-rays for ankle and/or middle-foot traumas in primary care. DESIGN: Observational, with application of the OAG and prospective measurement of the results.Setting. Hospital casualty. PATIENTS: Adults who attended casualty for ankle or middle-foot traumas between 1st June 1999 and 31th March 2000. Criteria for exclusion were: under 18, pregnancy, grave sensory and/or awareness disturbances, multi-trauma or multi-contusion patients, traumas over a week old, skin lesions as side-effects of the trauma, X-ray in other department, high inflammation or oedema hindering palpation of bone protuberances. MEASUREMENTS: Application of the OAG and X-ray on all patients, regardless of the result of the OAG. Calculation of sensitivity, negative predictive value, specificity and positive predictive value. RESULTS: 56 of a sample of 494 patients had a fracture (11.34%), 34 in the malleolus area (6.9%) and 22 in the middle-foot area (4.44%). OAG sensitivity was 96.43% (95% CI, 94.8-98). Negative predictive value was 97.22% (95.77-98.67). Specificity was 15.98% (12.75-19.21), and positive predictive value was 12.8% (9.86-15.74). CONCLUSIONS: The OAG are valid in primary care as guidelines to decide whether to request X-rays for patients with ankle or middle-foot traumas.

Reglas del Tobillo de Ottawa: análisis de su validez como reglas de decisión clínica en la indicación de radiografías en los traumatismos de tobillo y/o medio pie / The Ottawa ankle guidelines: analysis of their validity as clinical decision guidelines in the indications of X-rays for ankle and/or middle-foot traumas

Objetivo. Analizar la validez de las reglas del tobillo de Ottawa (RTO) como reglas de decisión en la indicación de radiografías en los traumatismos de tobillo y/o medio pie (TTM) en nuestro medio. Diseño. Observacional, con aplicación de las RTO y medición prospectiva del resultado. Ámbito. Urgencias hospitalarias. Pacientes. Adultos que acudieron a urgencias por TTM desde el 1 de junio de 1999 al 31 de marzo de 2000. Fueron criterios de exclusión: edad menor de 18 años, embarazadas, graves alteraciones sensoriales y/o de la conciencia, politraumatizados y/o policontusionados, traumatismos de más de una semana de evolución, lesiones cutáneas secundarias al traumatismo, realización de radiografía en otro ámbito, gran inflamación o edema que impidiera la palpación de los relieves óseos. Mediciones. Aplicación de las RTO y realización de radiografía a todos los pacientes, con independencia del resultado de aquéllas. Cálculo de sensibilidad, valor predictivo negativo, especificidad y valor predictivo positivo. Resultados. Sobre una muestra de 494 pacientes, 56 presentaron fractura (11,34 por ciento), 34 de la zona maleolar (6,9 por ciento) y 22 de la zona del medio pie (4,44 por ciento). La sensibilidad de las RTO fue del 96,43 por ciento (IC del 95 por ciento, 94,8-98 por ciento). El valor predictivo negativo fue del 97,22 por ciento (IC del 95 por ciento, 95,77-98,67 por ciento). La especificidad fue del 15,98 por ciento (IC del 95 por ciento, 12,75-19,21 por ciento) y el valor predictivo positivo, del 12,8 por ciento (IC del 95 por ciento, 9,86-15,74 por ciento). Conclusiones. Las RTO son válidas en nuestro medio como reglas de decisión a la hora de solicitar radiografías en los pacientes con TTM (AU)

Consumo legal de metadona en población drogodependiente de la provincia de Alicante / Legal consumption of methadone in drugdepending population of Alicante's province

Introducción. Los programas de tratamiento con metadona han evolucionado a lo largo dé la década de los noventa condicionados por la aparición de la infección por el VIH u otras patologías infecciosas ligadas a la vía de consumo, hasta consolidarse como uno de los programas de reducción de daños más difundidos. Las dosis recomendadas para la realización de estos tratamientos han ido modificándose progresivamente según se ha observado su importancia en la retención de los pacientes en el tratamiento. Objetivos. El objetivo del presente trabajo es doble: conocer las modificaciones ocurridas en las dosis dispensadas entre 19901997 y realizar una estimación del coste del principio activo consumido. Pacientes y método: Se han obtenido las dosis medias de los pacientes que reciben tratamiento en el Centro de Cruz Roja de Alicante. Así como la média de las dosis dispensadas desde segundo semestre de 990-1997. Se ha agrupado a los pacientes en tres intervalos de dosificación. En primer lugar, los pacientes que toman dosis inferiores a 40 mg/día. En segundo lugar, los pacientes que están en dosis comprendidas entre 40-80 mg/día y, por último, los pacientes que están en dosis superiores a 80 mg/día. Resultados. Existe un ascenso progresivo en la inclusión de pacientes en el tratamiento con metadona. En el segundo grupo hay un incremento sostenido que varía de una dosis media de 30 mg en el segundo semestre de 1990 a 47 mg en el último semestre de 1997. El porcentaje de pacientes que Se encuentra en el intervalo de 40-80 mg/día crece progresivamente. El consumo del principio activo de metadona fue de 1.129.126 mg en 1991 y esta cantidad aumentó a 10.920.751 mg en 1997. En 1991 el coste anual del principio activo para la preparación de las dosis diarias fue de 100.635 ptas; en 1997, de 821.954 ptas. El principio activo para una dosis media costó 3,5 ptas. en el año 1997. Conclusiones. Encontramos un incremento de la dosis media dispensada, aunque ésta se encuentra por debajo de las dosis recomendadas por la literatura. Se produjo un crecimiento exponencial en el consumo del principio activo para la preparación de la metadona, que fue indicativa del crecimiento. en la población atendida (AU)