Biomedical subjects
Publications and source records attributed to R F Drake.
We report a case of acromegaly diagnosed in the second trimester of pregnancy. Bromocriptine (7.5 mg per day) corrected visual field defects and suppressed prolactin secretion but did not reduce fasting growth hormone levels. We propose that suppression of physiologic lactotroph hyperplasia by bromocriptine may permit noninvasive management of pituitary adenomas during pregnancy.
High surface area platinum subjected to the appropriate electrical potential cycling regimes exhibits considerable electrocatalytic activity towards glucose oxidation. We have developed a special data processing method, the compensated net charge (CNC) method, to take advantage of the electrocatalytic activity of platinum. This method involves the determination of the net oxidation charge during one complete cycle of a cyclic voltammogram applied to the platinum electrode in a potentiodynamic mode. Under these conditions, the electrode response is very sensitive to glucose, completely insensitive to urea, and only moderately sensitive to amino acid concentration changes. Earlier work with other endogenous and exogenous potential co-reactants shows little interference. Data obtained in vitro and in vivo will be presented and discussed.
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A prerequisite for the development of an implantable artificial pancreas is the availability of a stable, long-life glucose sensor. Platinum (Pt) catalyzed electrodes have been demonstrated in vitro to show high sensitivity to glucose and long cycle life but are more sensitive to co-reactants compared with enzymatic methods. The authors developed a special data processing method (compensated net charge ratio, or CNCR) in which the measured electrode response is very sensitive to glucose, completely insensitive to urea, and only moderately sensitive to amino acids. Other endogenous and exogenous co-reactants show only minor interferences. The CNCR method involves the determination of the ratio of net oxidation charge to total charge during one complete cycle of a cyclic voltammogram. Prototype electrodes tested in vitro in spiked plasma have shown typical sensitivities of greater than 2 x 10(-4) CNCR units per 1 mg/dl change in glucose concentration, with linear response up to 400 mg/dl. For in vivo testing, a modified 5 F vascular catheter with membrane covered surface mounted electrodes was used at a vena cava site in swine. Several sensor designs were tested in vivo, with sensitivities of 1-5 x 10(-4) CNCR units (mg/dl).