Interaction of fluorinated ether anesthetics with artificial membranes.

Fluorine-19 nuclear magnetic resonance spectroscopy is applied to the study of the environment of dipalmitoyl phosphatidylcholine-bound fluorinated ether anesthetics (enflurane, fluoroxene and methoxyflurane) both below and above the lipid gel to liquid crystal phase transition temperature. Line widths and spin-lattice relaxation time (T1) measurements are consistent with substantial immobilization of the lipid-bound anesethetic molecules. Heating anesthetic/lipid mixtures above the lipid transition temperature leads to narrowing of the lipid-bound anesthetic fluorine resonances accompanied by little or no change in anesthetic fluorine-19 chemical shifts, suggesting that although the mobility of the bound anesthetic increases at the higher temperature, the nature of the anesthetic-lipid interaction changes little as a result of this phase change. Differential scanning calorimetric studies of the effects of these anesthetics on the phase transition behavior of the phospholipid indicate that the regions of the bilayer in which volatile anesthetics partition at lower concentrations are different from the regions in which they partition at higher concentrations.

Use of total-body electrical conductivity for the assessment of body composition in middle-aged and elderly individuals.

Body composition was predicted for 114 middle-aged and elderly individuals aged 35-90 y by using total-body electrical conductivity (TOBEC), densitometry, and hydrometry. Highly significant correlations were achieved between the TOBEC Phase value and fat-free mass (FFM) determined by densitometry (FFMd) and hydrometry (FFMdw) with values ranging from 0.713 to 0.981. TOBEC predicted FFM (FFMT) was consistently higher than either FFMd or FFMdw for both men and women in all age groups. A theoretical calculation of percent body fat was performed with a three-component model with body density, total body water, and bone mineral content. The recalculation of fat was used to estimate a new FFM (FFMnew). These calculations resulted in a decrease in fat and an increase in FFMnew. Because the TOBEC signal is unaffected by bone mineralization, FFMT may provide a more accurate estimation of body composition than do FFMd or FFMdw in this group of individuals.

Estimation of apparent quadrupolar coupling constants for complexes of magnesium ions with mono- and dicarboxylic acid ligands. Applications to magnesium ion: protein interactions.

25Mg+2 ion NMR studies of complexes of magnesium ions with acetate and malonate ligands have yielded apparent quadrupolar coupling constants, chi, of approximately 1.5 MHz. The aquo magnesium ion yields a smaller chi value of 0.12 MHz, consistent with its expected higher symmetry. chi values for magnesium ion: acetate and magnesium ion: malonate complexes are utilized to calculate observed linewidths for magnesium ion: bovine prothrombin fragment 1 and magnesium ion: human Factor XII interactions. These calculated values are compared with observed values and implications of the agreement are discussed.

Comparison of cardiovascular effects of pipecuronium versus vecuronium in patients receiving sufentanil anesthesia for myocardial revascularization.

This study was designed to compare the cardiovascular effects of pipecuronium bromide (PIP) to vecuronium (V) when combined with sufentanil (SF) in patients undergoing coronary artery bypass surgery. Eighty-two patients were studied; 40 were normotensive and 42 had hypertension currently controlled by pharmacological therapy. All patients were randomly assigned to receive either intravenous V, 0.12 mg/kg, or PIP, 0.10 mg/kg. Anesthesia was induced with SF, 6 micrograms/kg, while breathing 100% oxygen. Hemodynamic data including heart rate, mean arterial pressure, pulmonary capillary wedge pressure, central venous pressure, cardiac index, systemic vascular resistance, pulmonary vascular resistance, and left ventricular stroke work index were collected at five points: prior to induction, 3 and 6 minutes after the complete administration of PIP or V, and 3 and 6 minutes after intubation. There were no statistical differences in hemodynamic changes associated with either PIP or V. In addition, there were no statistical differences in the hemodynamic parameters measured at the five time points between the normotensive and hypertensive patient groups. This study demonstrates that there are no significant hemodynamic changes between SF/PIP and SF/V when used during coronary artery surgery. Due to its associated stable hemodynamics, as well as its long duration of action, PIP could become a commonly used muscle relaxant for anesthesia for cardiac surgery.