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Electrode, subcutaneous

Although electrical shock has been used widely as a nociceptive stimulus for evaluating opiate activity, problems do arise in controlling the intensity of stimulus thus, electrode currents and vdtages may be readily maintained where as the impedance of the biological tissues can be extremely variable, thereby producing data of poor reproducibility [29 2]. The variability of data can be reduced when the animals can act as their own controls and also by chronically implanting electrodes subcutaneously sometime before the experiment so that impedance is minimised [SI]. [Pg.256]

Most of the recent attention has been given to the development of subcutaneously implantable needle-type electrodes [14, 15, 34, 38], Such devices track blood glucose levels by measuring the glucose concentration in the interstitial fluid of the subcutaneous tissue (assuming the ratio of the blood/tissue levels is constant). Subcutaneously implantable devices are commonly designed to operate for a few days and be replaced by the patient. Success in this direction has reached the level of short-term human implantation ... [Pg.88]

E. Csoregi, D.W. Schmidtke, and A. Heller, Design and optimzation of a selective subcutaneously implantable gluocse electrode based on wired glucose oxidase. Anal. Chem. 67, 1240-1244 (1995). [Pg.91]

E Moussy and D.J. Harrison, Prevention of the rapid degradation of subcutaneously implanted Ag/AgCl reference electrodes using polymer coatings. Anal. Chem. 66, 674-679 (1994). [Pg.324]

Figure 17-11 Response of an cmperometric glucose electrode with dissolved 02 concentration corresponding to an oxygen pressure of 0.027 bar, which is 20% lower than the typical concentration in subcutaneous tissue. [Data from S.-K. Jung and G. W. Wilson, "Polymeric Mercaptosilane-MocMed Platinum Electrodes lor Elimination of Interfer-ants in Glucose Biosensors," Anal. Chem. 1996,68.591.]... Figure 17-11 Response of an cmperometric glucose electrode with dissolved 02 concentration corresponding to an oxygen pressure of 0.027 bar, which is 20% lower than the typical concentration in subcutaneous tissue. [Data from S.-K. Jung and G. W. Wilson, "Polymeric Mercaptosilane-MocMed Platinum Electrodes lor Elimination of Interfer-ants in Glucose Biosensors," Anal. Chem. 1996,68.591.]...
It should also be pointed out that in the case of an in vivo measurement, the microdialysis probe will be able to recover not only glucose but also many other biological compounds with low molecular weight from the subcutaneous tissue. The electrochemical interferents are greatly reduced by the use of PB at a low applied potential. However, other biological compounds could negatively affect the stability of the enzymatic membrane. Also, it is possible to have a sort of passivation or fouling of the electrode surface due to the absorption of... [Pg.574]

Csoregi E, Quinn CP, Schmidtke DW, Lindquist SE, Pishko MV, Ye L, Katakis I, Hubbell JA, Heller A. Design, characterization, and one-point in vivo calibration of a subcutaneously implanted glucose electrode. Analytical Chemistry 1994,66, 3131-3138. [Pg.25]

Kemer W, Kiwit M, Linke B, Keck FS, Zier H, Pfeiffer EF. The function of hydrogen-peroxide-detecting electroenzymatic glucose electrode is markedly impaired in human subcutaneous tissue and plasma. Biosensors Bioelectronics 1993, 8, 473. [Pg.108]

In contractile experiments the time from the stimulation of the nerve to the CMAP recorded in muscle provides an estimate of NCV. The length of the nerve from the stimulating electrode to the muscle can simply be measured and divided by the time. However, the time recorded in this way includes the delay for synaptic transmission, which may be increased in models with synaptic defects. If this is a concern or if the only parameter desired is NCV, then the measurement can be obtained non-invasively with a relatively simple setup (e.g., (3)). Using the sciatic nerve, NCV can be calculated by measuring the latency of compound motor action potentials recorded in the muscle of a rear paw. Action potentials are produced by subcutaneous stimulation at two separate sites proximal stimulation at the sciatic notch and distally at the ankle. NCV is then calculated by using the two latencies and conduction distance. Decreases in nerve conduction velocity most often reflect defects in myelination, but may also be the result of changes in internodal distance, decreased axon diameters, or altered excitability. [Pg.383]

Therefore, another type of planar glucose biosensor with Pt electrodes on a sihcon substrate has therefore been developed for in vivo measurements [61]. The enzyme glucose oxidase was immobilized by the well known GDA-BSA method and the whole sensor was covered subsequently by a polyurethane membrane. This sihcon chip has to be sawed and assembled on a flexible carrier for in vivo application, the assembled catheter was successfully evaluated in rats [79]. This sensor gives encouraging results in aqueous solutions and subcutaneous apphcations. Drawbacks of this include the complicated mounting and assembling procedures which are difficult and cumbersome. [Pg.198]

The LCX is punctuated distal to the flow probe with a chrome-vanadium-steel electrode (3 mm length, 1 mm diameter). The electrode (anode) is placed in the vessel in contact with the intimal lining and connected over a Teflon coated wire to a 9 Volt battery, a potentiometer and an amperemeter. A disc electrode (cathode) is secured to a subcutaneous thoracal muscle layer to complete the electrical circuit. The intima is stimulated with 150 pA for 6 h. During this time, gradually an occluding thrombosis is formed. [Pg.279]

The use of electrical current to induce thrombosis in hamster and dog has been described in the early 1950s by Lutz et al. (1951) and Sawyer and Pate (1953a,b). In general, two different approaches exist. One method produces electrical damage by means of two externally applied hook-like electrodes (Hladovec 1973 Philp et al. 1978). The other method uses a needle electrode which is advanced through the walls of the blood vessels and positioned in their lumen the second electrode is placed into a subcutaneous site completing the circuit (Salazar 1961 Romson et al. 1980 Benedict etal. 1986). [Pg.284]

Rote et al. (1993, 1994) used a carotid thrombosis model in dogs. A calibrated electromagnetic flow meter was placed on each common carotid artery proximal to both the point of insertion of an intravascular electrode and a mechanical constrictor. The external constrictor was adjusted with a screw until the pulsatile flow pattern decreased by 25 % without altering the mean blood flow. Electrolytic injury to the intimal surface was accomplished with the use of an intravascular electrode composed of a Teflon-insulated silver-coated copper wire connected to the positive pole of a 9-V nickel-cadmium battery in series with a 250000 ohm variable resistor. The cathode was connected to a subcutaneous site. Injury was initiated in the right carotid artery by application of a 150 xA continuous pulse anodal direct current to the intimal surface of the vessel for a maximum duration of 3 h or for 30 min beyond the time of complete vessel occlusion as determined by the blood flow recording. Upon completion of the study on the right carotid, the procedure for induction of vessel wall injury was repeated on the left carotid artery after administration of the test drug. [Pg.285]

Their biosensor consisted in a Pt wire on which GOD was immobilized by the electropolymerization of m-phenylenediamine. The advantage of this type of immobilization consists in creating an effective barrier against electrochemical interference due to the polymer formed onto the electrode. Moreover, an extended linearity for the glucose sensor was also obtained, and this was a requisite for the direct measurement of the subcutaneous glucose at diabetic levels, since in practice an extremely low dilution of the subcutaneous fluid was realized. [Pg.245]

Kissinger [130] carried out similar experiments following lactate changes observed in a rat subcutaneous microdialysate upon an intraperitoneal injection of lactate. The half-life of the sensor, assembled by coating the enzyme lactate oxidase (LOD) on a glassy carbon electrode with an Os-redox polymer and a Nafion overcoating, was about 24 h. [Pg.250]

Several implanted biosensors have been developed and evaluated in both animals and humans (see Chapter 4). Detection systems are based on enzymes, electrodes, or fluorescence. The most widely studied method is an electrochemical sensor that uses glucose oxidase. This sensor can be implanted intravenously or subcutaneously. Intravenous implantation in dogs for up to 3 months has demonstrated the feasibility of this approach. Alternatives to enzymes are being developed, including artificial glucose receptors. Less success has been achieved with subcutaneous implants. Implantation of a needle type of sensor into the subcutaneous tissue induces a host of inflammatory responses that alters the sensitivity of the device. Microdialysis with hoUow fibers or ultrafiltration with biologically inert material can decrease this problem. [Pg.875]

First needle-type enzyme electrode for subcutaneous implantation by Shichiri [128[. [Pg.10]

Wagner, J.G., Schmidtke, D.W., Quinn, C.P., Fleming, T.F., Bernacky, B., and Heller, A. (1998) Continuous amperometric monitoring of glucose in a brittle diabetic chimpanzee with a miniature subcutaneous electrode. Proceedings of the National Academy of Sciences of the United States of America,... [Pg.67]


See other pages where Electrode, subcutaneous is mentioned: [Pg.46]    [Pg.82]    [Pg.313]    [Pg.620]    [Pg.255]    [Pg.113]    [Pg.132]    [Pg.976]    [Pg.373]    [Pg.374]    [Pg.374]    [Pg.575]    [Pg.89]    [Pg.94]    [Pg.221]    [Pg.272]    [Pg.212]    [Pg.368]    [Pg.2749]    [Pg.246]    [Pg.246]    [Pg.346]    [Pg.96]    [Pg.10]    [Pg.67]   
See also in sourсe #XX -- [ Pg.97 ]




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Subcutaneous

Subcutaneously

Subcutaneously implantable needle-type electrodes

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