Showing papers on "Glucose Measurement published in 1991"

Fingerstick glucose determination in shock.

Abstract: Objective: To evaluate the accuracy of fingerstick glucose measurements in severely hypotensive patients. Design: Prospective, nonrandomized comparison study. Setting: Emergency department in a uni...

A predictive and feedback control algorithm maintains a constant glucose concentration in fed-batch fermentations.

Abstract: A combined predictive and feedback control algorithm based on measurements of the concentration of glucose on-line has been developed to control fed-batch fermentations of Escherichia coli. The predictive control algorithm was based on the on-line calculation of glucose demand by the culture and plotting a linear regression to the next datum point to obtain a predicted glucose demand. This provided a predictive "coarse" control for the glucose-based nutrient feed. A direct feedback control using a proportional controller, based on glucose measurements every 2 min, fine-tuned the feed rate. These combined control schemes were used to maintain glucose concentrations in fed-batch fermentations as tight as 0.49 +/- 0.04 g/liter during growth of E. coli to high cell densities.

Reagentless hydrogen peroxide and glucose sensors based on peroxidase immobilized on graphite electrodes

Abstract: The electrocatalytic reduction of hydrogen peroxide (H2O2) by horseradish peroxidase (HRP) immobilized on graphite electrodes without the addition of an electron mediator was found to start at + 600 mV vs. Ag/AgCl and the highest current was obtained at about −100 mV. With an applied potential of −50 mV and in the absence of soluble mediator, linear calibration curves for H2O2 were obtained between 0.5 μM and 250 μM and for β-D-glucose in air-saturated solution between 2 μM and 0.5 μM (HRP co-immobilized with glucose oxidase). Cross-linking the enzymes with glutaraldehyde and bovine serum albumin was found to increase the stability of the sensors without causing mass transfer resistance within the enzyme layer. The response time was 5 seconds both for H2O2 and for glucose and the sample through put was 150 samples h−1. The glucose measurements were made in 0.1 M phosphate buffer, pH 6, where no interfering from physiological levels of ascorbic acid, uric acid, or paracetamol (acetaminophen) could be detected.

Amperometric substrate determination in flow-injection systems with polypyrrole—enzyme electrodes

Abstract: Polypyrrole/glucose oxidase electrodes with the enzyme covalently bound to the outer surface of the functionalized polymeric network are used together with a similarly prepared non-enzyme electrode to determine glucose in the presence of cooxidizable compounds in fruit juices and wines. Due to the size-exclusion properties of polypyrrole, the thicknesses of the conducting polymer layers at both electrodes have to be equal to allow interfering compounds to be discriminated. A significant improvement with respect to the reliability of glucose measurements in real samples and the number of analyses with time is possible with these systems, as is proved by comparison with standard spectrophotometric procedures.

Influence of urea on the glucose measurement by electrocatalytic sensor in the extracorporeal blood circulation of a sheep.

Abstract: In an animal experiment with the electrocatalytic glucose sensor, measurements were carried out over one week in the extracorporeal circulation of a sheep. Glucose tolerance tests were performed, and the influence of increased urea concentrations in the blood on the glucose determination was investigated. The sensor constructed as a flow-through cell was integrated via a vascular graft outside the body into the carotid artery of the animal and activated by an external electronic unit of measurement. The glucose concentration was determined by measuring the impedance of the electrode/membrane system at various potentials. By means of a subsequent correlation analysis of the measured values obtained over one week, a calibration valid for the entire measurement period was established. After a zero adjustment, it was even possible to adopt the calibration from the glucose measurement of the preceding animal experiment. The investigations of the influence of urea on the glucose measurement showed that the error in measurement of the sensor, which is 20% on average, is only insignificantly increased when the urea level is raised beyond the maximum physiological concentration.

Capillary and venous blood glucose measurements using a direct glucose-sensing meter.

Abstract: The aim of the study was to evaluate the precision and accuracy of the ExacTech home blood glucose meter when used with either capillary or venous blood and to compare this with a reference whole blood glucose assay. Non-fasting glucose measurements were used since a validation study showed no capillary-venous differences between fasting and post-prandial states. In a cross-sectional study, blood was taken from 182 patients and measured in duplicate on three batches of strips. Altogether we analysed 1089 readings. The regression of the data from capillary blood samples (meter vs reference method) had a correlation coefficient, of 0.93, and a mean bias of 0.2 mmol l-1. The corrected 90% confidence interval was +/- 1.5 mmol l-1 overall, and +/- 0.9 mmol l-1 for readings under 7.0 mmol l-1. Regression of the data from venous blood samples (meter vs reference method) had a correlation coefficient of 0.93 and a slope of x 1.1. The corrected 90% confidence interval was +/- 1.7 mmol l-1. Thus venous blood may be used even though the meter is calibrated for capillary samples but the value must be corrected by dividing by 1.1. Error-grid analysis showed that day-to-day clinical decisions could be made on the basis of ExacTech readings, although a diagnosis of borderline diabetes may not be possible.

New whole blood methods and instruments: glucose measurement and test menus for critical care.

Abstract: A glucose oxidase-H 2O 2 substrate-selective electrode (SSE) along with eight other electrodes allows the Stat Profile 5 (SP5) to measure glucose, electrolytes, blood gases, pH, and hematocrit simultaneously in whole blood. For heparinized blood gas syringe samples (n=178), orthogonal (Deming) regression showed y=0.43 + 1.00x (mmol/L), where y is whole blood glucose, and x is plasma glucose measured with the Ektachem 400 glucose oxidase slide method. For heparinized plasma (n=197), y=0.25 + 1.02x. Least squares linear regression showed y=0.25 + 1.00x (s yxx=0.49) for whole blood versus plasma, y = 0.30 + 1.01x (s yxx=0.49) for plasma versus plasma, and r=0.994 for both cases. Whole blood and plasma glucose in the same samples measured by SSE differed by less than 1%. The SP5 combines the largest number of whole blood tests currently available in a rapid response instrument well-suited for care of the critically ill patient.

Automation of glucose measurement in fermentor broths

Abstract: A semi-on-line automated analysis for fermentation is presented. The system consists of a modified commercial biosensor analyser YSI 27 and a Gilson dilutor injector. The results of direct glucose monitoring in fermentation broths are presented. Measurements, calibrations and washes are completely automated, with a maximum analysis frequency of 16 per hour with dilutions. The detection limits are 50 mg/1 and 41 g/1 with good linearity and a precision of ±5%.

Safe, stable, whole blood samples for quality assessment of glucose measurement by non-laboratory staff.

Abstract: A whole blood control material has been used to assess the analytical performance of non-laboratory staff who use glucose meters in clinical areas. It is prepared from sterile horse blood which is readily available from a commercial source. There are no known infection or disease transmission risks to users. When the material is stabilized by the addition of sodium fluoride less than 3% loss of glucose over 48 h is observed from an initial value of 10 mmol/L. However, we prefer to stipulate that the glucose is measured on the day of receipt. The material has been used successfully with Reflolux IIM meters and B-M sticks (Boehringer Mannheim, UK) for over a year in our hospital.

Glucose non-invasive measuring method

Abstract: PURPOSE:To enhance practical non-invasive glucose measurement by ntilizing near infrared rays comparatively satisfactorily permeating in a living body tissue to permeate a measuring light to a depth in which capillary exists, and selecting an optimum measuring wavelength band. CONSTITUTION:When the spectral absorptive spectrum of a living body tissue containing moisture is measured, the peak of absorption by water is found in the vicinity of 1.4, 1.5 and 1.9-2mum, and the patterns of absorption related to the kind and concentration of the materials contained in the tissue are also observed even in other wavelengths. As a result of experiments, it was found that the use of a wavelength band of 1600-1750nm as the absorption wavelength band by the glucose in the aqueous solution and 1200-1300nm as a standard wavelength band having no relation to absorption of glucose is practically desired. Thus, by utilizing the near infrared rays in these bands, the light can be permeated into the living body tissue, and also, as the spectral absorption characteristic of the glucose contained in the living body has a fixed relation to the glucose concentration, the glucose concentration in the living body can be measured without invasion.

Glucose measurement control reagent

Abstract: The invention relates to a serum-free control reagent for glucose determination. Rather than using modified serum, the control reagent contains water, glucose, and the viscosity agent polystyrene sulphonate. The control reagent may also contain a buffer, preservatives, and surfactants or surface active agents.