Multilayer film elements for clinical analysis: general concepts.

Abstract

Dry, thin films containing all necessary reagents for clinical analysis by colorimetry have been designed. Reagents in a matrix of hydrophilic polymer are coated on top of a transparent plastic base. A white isotropically porous polymer spreading layer, 80% void volume, is coated over the reagent layer(s). In the analysis, a drop (typically 10 microliter) of undiluted serum or other fluid is touched to the spreading layer. The fluid spreads rapidly and uniformly through the pore structure, filling a void volume corresponding to the drop volume. Water and low-molecular-weight components diffuse from the spreading layer into the reagent layer(s), initiating the reaction sequence. The spreading layer acts also as a white optical diffuser for reflection densitometry. Optical reflection density is linearized through use of the function developed by Williams and Clapper [J. Opt. Soc. Am. 43, 595 (1953)] to convert reflection to transmission density. A wide variety of chemical assays are compatible with this format. As an example, for the glucose film we found coefficients of variation of 1.5% in predicting glucose concentrations in control sera during 20 days. Results for glucose concentrations in several hundred patients' sera by the present method were very cose to those obtained with the Center for Disease Control's hexokinase reference method.

Exercise Performance is not Influenced by a 5-HT Reuptake Inhibitor

“…However, it appears that at very high dosages 5-HT agonists promote some components of the so called 5-HT behavioural syndrome, including the 5-HT mediated head shake response [18,25,33]. This behaviour is likely to negatively interfere with performance explaining the dose dependent decrease in time to exhaustion seen in rats after quipazine treatment, a non selective 5-HT receptor agonist [4].…”

“…Glucose and ammonia were assayed with an Ektachem 750C analyzer (Johnson & Johnson Clinical Diagnostics, Rochester, New York, USA). For glucose an enzymatic procedure [18], and NH 3 a colometric procedure was used. For free fatty acids (FFA) determination a Cobras Mira S analyzer (Hoffman-La Roche & Co., Basel, Switzerland) was used, following the method described by Demacker et al [21].…”

Problems and possibilities of chemistry on dry reagent carriers

“…A disadvantage of the film system that becomes evident in analysis of its theoretical model, however, is that its dose response character is distinctly non-linear. It requires a three point calibration [3]. In the case of diffuse reflectance, and application of Kubelka-Munk theory, linear response regions can be developed, and a two point calibration is all that is required.…”

Benefícios da modificação do estilo de vida na síndrome metabólica

“…Triglyceride analysis was based on an enzymatic method described by Spayd et al (18). Glucose analysis was performed based on the method previously described by Trinder (19) and Curme et al (20). The glucose, total cholesterol, HDL and triglyceride concentrations were obtained using reflectance spectrophotometry.…”