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Biomedical subjects

D L Bruce

Publications and source records attributed to D L Bruce.

At least 73 records · Page 4Linked to original sources
PubMed1965

Some ionic and bioelectric properties of the ameba Chaos chaos.

Ionic relationships in the giant ameba Chaos chaos were studied by analyzing bulk preparations of ground cytoplasm for K, Na, and Cl. Ion levels under normal conditions were compared with the levels in cells exposed to varying concentrations of different ions, for varying times and at different temperatures. By standard intracellular electrode techniques, the bioelectric potential, electrical resistance, and rectifying properties of the plasmalemma were studied on intact cells in media of different composition. The results obtained, when related to evidence from other studies on ion fluxes and osmotic relationships, suggest the following concept of ionic regulation in Chaos chaos. In the absence of active membrane uptake, the plasmalemma is essentially impermeable to anions but permeable to both K and Na, which enter passively. In the cold the cell does not discriminate between K and Na, the cytoplasmic level of K + Na is determined by a Donnan distribution, and osmotic imbalance leads to slow swelling. At normal temperatures active processes are added: Na and water are pumped out by the contractile vacuole system; Cl is accumulated, along with the colloid components of the cytoplasm, only during feeding and growth, which depend upon membrane uptake and intracellular membrane transformations. There is no evidence for active transport of any ion species directly across the plasmalemma.

Amoeba↗
PubMedDate not supplied

Delayed awakening due to lidocaine overdose.

An 86-year-old man receiving antiarrhythmic treatment with an intravenous (IV) lidocaine infusion experienced a prolonged emergence from general anesthesia. A venous blood sample was sent for determination of the lidocaine concentration, the infusion was stopped, and the patient awakened 15 minutes later. The circulating lidocaine concentration was 15.6 micrograms/ml, three times the upper limit of therapeutic range for arrhythmia treatment. The overdose was the result of a miscalculated infusion rate, plus an underestimation of effects of age, cardiac disease, and general anesthesia on the rate of lidocaine biotransformation. Infusion of any drug during and after general anesthesia requires scrupulous attention to dosage determination and to the clinical condition of the patient receiving the infusion.

Aged↗
PubMedDate not supplied

Thiopental and succinylcholine: Action on intraocular pressure.

Intraocular pressure (IOP) measurements were made in a series of 92 male surgical patients, to assess the effects of timing and dosage of succinylcholine given after a standardized sleep dose of thiopental (3 mg./kg.). The major findings of this study were as follows: (1) thiopental alone lowered IOP; (2) a small (0.5 mg./kg.) dose of succinylcholine, given immediately after thiopental, returned IOP to normal; (3) a large (1 mg./kg.) dose of succinylcholine immediately after thiopental maintained the IOP at a low value; (4) if 2 minutes elapsed between thiopental and 1 mg./kg. of succinylcholine, the relaxant raised the IOP to slightly above preanesthetic control values; (5) tracheal intubation caused a significant rise in IOP, more than any effect from succinylcholine itself; (6) succinylcholine drip (0.1 percent), begun after establishment of satisfactory endotracheal halothane-nitrous oxide anesthesia, caused significant IOP elevation in 4 of 11 patients.

Adult↗
PubMedDate not supplied

Intraocular pressure changes during anesthesia for electroshock therapy.

Intraovular pressure was measured in 20 patients undergoing anesthesia for electroshock therapy. Compared to control values, determined on the day before electroshock therapy, statistically significant elevations of intraocular pressure followed the post-electroshock therapy convulsions and were still significant 5 minutes later, but not of sufficient magnitude or duration to cause concern.

Adult↗