"Glucosensor Unitec Ulm". A portable, continuously measuring glucose sensor and monitor

The "Glucosensor Unitec Ulm" is the first commercially available, portable glucose monitor that permits continuous measurement in venous blood under ambulatory conditions for up to 256 hours. The device weights 850 g, and measures 15 x 19 x 7 cm. Depending on the flow rate of the pump, the blood requirement is 15-25 ml/24 h. The size of the built-in-memory is 32 kByte, enough to store 3180-15,900 glucose values. The "24 hour glucogram" obtained under day to day living conditions permits the detection of disturbances of carbohydrate metabolism. Thus, early abnormalities of type II diabetes can be detected as well the degree of blood glucose normalization in patients suffering from severe insulin-dependent diabetes. Moreover, the effects of glucose-lowering drugs can be analyzed objectively. Finally, this portable glucose monitor permits the recognition of hypoglycemia induced by insulin administration or endogenous insulin overproduction due to tumors.     

A conductive polymer sensor for measuring external finger forces.

This paper describes the construction and use of a durable and thin force sensor that can be attached to the palmar surface of the fingers and hands for studying the biomechanics of grasp and for use in hand injury rehabilitation. These force sensors were constructed using a modified commercially available conductive polymer pressure sensing element and installing an epoxy dome for directing applied forces through a 12 mm diameter active sensing area. The installation of an epoxy dome was effective for making the sensors insensitive to contact surfaces varying from 25 to 1100 mm2 and a 16 mm radius surface curved convex towards the finger. The completed sensors were only 1.8 mm thick and capable of being taped to the distal phalangeal finger pads. They were calibrated on the hand by pinching a strain gage dynamometer. The useful range was between 0 and 30 N with an accuracy of 1 N for both static loading and normal dynamic grasp activities. The sensor time constant was 0.54 ms for a step force input. Because of varying offset voltages every time the sensors were attached, these sensors should be calibrated on the hand before each use. The sensors were used for measuring finger forces during controlled pinching and lifting tasks, and during ordinary grasping activities, such as picking up a book or a box, where the useful force range and response for these sensors were adequate.     

The continuously fed batch reactor for measuring microbial growth rates

The contiuously fed batch reactor (CFBR) is proposed as an alternative technique to the traditional chemostat and batch cultures, for measuring microbial growth rates. After reviewing the pitfalls which plague the conventional growth measurement techniques, the methodology for operating the CFBR to generate specific growth-rate-versus-substrate-concentration data is detailed. This information is extracted from the transient state of the CFBR where both the biomass and substrate concentration show extrema in time. It is suggested that the CFBR can be used for measuring microbial growth rates at low rates at low substrate concentrations where the chemostat method normally encounters difficulties.     

A new method for measuring passive length-tension properties of human gastrocnemius muscle in vivo

The study of muscle growth and muscle length adaptations requires measurement of passive length-tension properties of individual muscles, but until now such measurements have only been made in animal muscles. We describe a new method for measuring passive length-tension properties of human gastrocnemius muscles in vivo. Passive ankle torque and ankle angle data were obtained as the ankle was rotated through its full range with the knee in a range of positions. To extract gastrocnemius passive length-tension curves from passive torque-angle data it was assumed that passive ankle torque was the sum of torque due to structures which crossed only the ankle joint (this torque was a 6-parameter function of ankle joint angle) and a torque due to the gastrocnemius muscle (a 3-parameter function of knee and ankle angle). Parameter values were estimated with non-linear regression and used to reconstruct passive length-tension curves of the gastrocnemius. The reliability of the method was examined in 11 subjects by comparing three sets of measurements: two on the same day and the other at least a week later. Length-tension curves were reproducible: the average root mean square error was 5.1+/-1.1 N for pairs of measurements taken within a day and 7.3+/-1.2 N for pairs of measurements taken at least a week apart (about 3% and 6% of maximal passive tension, respectively). Length-tension curves were sensitive to mis-specification of moment arms, but changes in length-tension curves were not. The new method enables reliable measurement of passive length-tension properties of human gastrocnemius in vivo, and is likely to be useful for investigation of changes in length-tension curves over time.     

Thermoelectric enzyme sensor for measuring blood glucose

A new calorimetric sensor has been developed which employs a thin-film thermopile in association with an immobilized enzyme. The thermopile detects the minute temperature rise that occurs when a specific chemical substrate is catalyzed by the enzyme. A prototype sensor is described which generates an equivalent proportional voltage response to glucose concentrations present in either buffer solution or blood. These sensors have remained useful for up to 18 days when operated intermittently for measuring glucose in buffer solutions, or for up to 4 days when operated continuously. When implanted inside cardiovascular shunts on anesthetized dogs, the sensors responded appropriately to changes in the blood glucose concentration.     

Target intraocular pressure in the management of glaucoma

Achievement of target intraocular pressure is the goal of every efficient antiglaucoma therapy. Target intraocular pressure is the level of intraocular pressure which is associated with minimal likelihood of visual field or optic nerve lesion, or an existing lesion progression due to elevated intraocular pressure. Results of large clinical studies which have offered some new concepts on target intraocular pressure in the management of glaucoma are reviewed. An association between the curve of intraocular pressure decrease and glaucoma progression was demonstrated in these studies. Generally, a lower value of target intraocular pressure implies better protection from the loss of vision and visual field impairment in glaucoma patients. In advanced glaucoma, the greatest possible reduction from the initial intraocular pressure should be attempted. A 20% reduction from the initial intraocular pressure or decrease to < 18 mmHg in advanced glaucoma has been recognized as a favorable strategy to reach target intraocular pressure. In normal tension glaucoma, a lower value of target intraocular pressure is associated with a slower disease progression. In patients with initial glaucoma, 25% reduction from the initial intraocular pressure will slow down the disease progression by 45%. The value of target intraocular pressure depends on the pretreatment level of intraocular pressure, optic nerve condition, glaucoma disease state, rate of glaucoma progression, patient's age, and other risk factors for the development of glaucoma.     

A practical measuring system for intestinal pressure activity and its clinical application

AimTo propose a practical, non-invasive method for monitoring intestinal pressure activity and introduce its clinical application on discrimination between the healthy subjects and the slow transit constipation (STC) patient subjects in the sense of medical statistics.MethodsNineteen healthy subjects and eight STC patient subjects participated in the experiments. The authors tried to find the optimal feature combination by using the probabilistic neural network (PNN) to separate these two groups and test their significant differences.ResultsThe statistical analysis revealed that the combination of the frequency and the average pressure of the pressure activity induced by colonic peristalsis was the optimal feature combination among the possible feature subsets, which was composed of several typical extracted features, and the discrimination accuracy of test samples was about 88.89%. The one-way analysis of variance (ANOVA) analysis also showed that there were differences or significant differences between them.ConclusionsClinical experiments and analysis method related verified the practicability of the system, and the measurement technology developed for monitoring intestinal pressure activity was useful.     

A chamber system with automatic opening and closing for continuously measuring soil respiration based on an open-flow dynamic method

We developed an automatic opening and closing chamber system (AOCC) based on an open-flow dynamic method (open-flow AOCC). The AOCC can be used during all four seasons, even at the surface of relatively deep snow. We compared the open-flow AOCC with two closed dynamic methods [the AOCC configured as a closed dynamic system (closed dynamic AOCC) and the LI-6400 system] under field conditions. The closed dynamic-AOCC and LI-6400 measurements were about 15.4% and 5.2% lower, respectively, than the values obtained with the open-flow AOCC. There was a significant difference in soil respiration rate between the open-flow AOCC and the closed dynamic AOCC system. In contrast, no significant difference in soil respiration rate was detected between the open-flow AOCC and the LI-6400 system. In the field, the open-flow AOCC permitted continuous long-term measurements under a range of temperature conditions and did a good job of reflecting the marked daily and seasonal variations in soil respiration as a function of soil temperature.