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Biomedical subjects

D A Noe

Publications and source records attributed to D A Noe.

44 records · Page 3Linked to original sources
PubMed1984

Direct spectrophotometry of serum hemoglobin: an Allen correction compared with a three-wavelength polychromatic analysis.

An Allen correction and a polychromatic analysis are about equally effective in minimizing effects of interference by bilirubin and triglyceride turbidity in the direct spectrophotometry of serum hemoglobin: interference from bilirubin is nearly eliminated, that from turbidity substantially decreased. The limit of detectability of hemoglobin is 8 mg/L in the presence of a moderate concentration of bilirubin. A change in hemoglobin concentration as small as 16 mg/L can be detected in serum having a concentration near the upper limit of the reference interval, i.e., at the medical decision level. The polychromatic formula gives concentration estimates approximately 5% greater than those of the Allen correction. The formula for the Allen correction is hemoglobin (mg/L) = 1.68 mA415 - 0.84 mA380 - 0.84 mA450 . That for the polychromatic analysis is hemoglobin (mg/L) = 1.65 mA415 - 0.93 mA380 - 0.73 mA470 .

Bilirubin↗
PubMedDate not supplied

Platelet counts during rapid massive transfusion.

The effect of rapid massive transfusion upon platelet counts has been studied retrospectively in 24 patients treated for severe trauma. Multiple linear regression analysis showed that a platelet dilution model with an exponential form described the quantitative relationship between the pre- and posttransfusion platelet counts and the volumes of blood products administered. Intravenous salt solutions had very little effect upon the platelet count even when large volumes were infused. Red blood cell transfusions decreased the platelet count to an extent two and one-half times greater than that of colloid infusions. The differences in the magnitudes of the dilution effects are attributable to the different physiologic volumes of distribution of the various classes of infusates. If only red blood cells (RBC) and fresh frozen plasma (FFP) are transfused, two useful equations obtain. First, the current platelet count (Pt) can be predicted knowing the initial platelet count (Po) and the number (#) of units of RBC and FFP administered: Pt = Po (0.634) e-0.046 [#RBC + #FFP/8]. Second, the point during massive transfusion when platelet transfusions will be necessary can be predicted knowing the initial platelet count.

Colloids↗
PubMedDate not supplied

A mathematical model of coagulation factor VIII kinetics.

It appears that the binding of coagulation factor VIII to von Willebrand factor in plasma stabilizes the otherwise highly labile factor VIII. A mathematical model of factor VIII kinetics has been developed based upon this proposed effect of factor VIII binding. The model's kinetic parameter values have been estimated by fitting the model to data available in the medical literature. The model gives accurate quantitative predictions of the elevated steady-state concentrations of factor VIII in clinical conditions associated with the acute phase reaction and in pregnancy, the decreased steady-state concentrations of factor VIII in females heterozygous for hemophilia, the decreased steady-state concentrations of factor VIII in patients with type 1 (heterozygous) and type 3 (homozygous) von Willebrand disease, and the variable half-life of factor VIII in factor replacement therapy for hemophilia and von Willebrand disease.

Computer Simulation↗
PubMedDate not supplied

Plasma pharmacokinetics and urinary excretion of thalidomide after oral dosing in healthy male volunteers.

The plasma pharmacokinetics and urinary excretion of thalidomide have been evaluated in eight healthy male volunteers receiving a single oral dose of 200 mg. Concentrations of thalidomide were determined by a new HPLC assay. Plasma concentration vs. time data were well fit by a one-compartment model. The mean (+/- SD) peak concentration, 1.15 +/- 0.2 microgram/ml, was achieved at 4.39 +/- 1.27 hr. Absorption and elimination half-lives were 1.70 +/- 1.05 hr and 8.70 +/- 4.11 hr, respectively, with a lag time of 0.41 +/- 0.17 hr observed in six subjects. The apparent volume of distribution and total body clearance rate, based on assumed complete bioavailability, were 120.69 +/- 45.36 liters and 10.41 +/- 2.04 liters/hr. The urinary excretion of thalidomide accounted for only 0.6 +/- 0.22% of the total dose administered over 24 hr, and the renal clearance rate was 0.08 +/- 0.03 liter/hr. This suggests that the major route of elimination of thalidomide is nonrenal.

Administration, Oral↗
PubMedDate not supplied

Kinetic analysis of the reaction of melphalan with water, phosphate, and glutathione.

The reaction kinetics of the hydrolysis, phosphatolysis, glutathionyl conjugation, and alpha-glutathione-S-transferase (GST)-catalyzed glutathione conjugation of [3H-ring]melphalan were investigated at pH 6.5 and 7.4. The distribution of products relative to the initial parent compound radioactivity over time was measured by HPLC and analyzed by nonlinear regression techniques using a system of rate and distribution equations that describe the complete precursor-product pathways applicable to each reaction condition. The kinetic parameters calculated in the analysis were the first- and second-order rate constants of formation and the product ratios of the aziridinium intermediates. The second-order rate constants were normalized to those obtained for the hydroxylation reactions to yield relative rate constants. The first-order rate constants of aziridinium ion formation from melphalan and from all the monosubstituted melphalan species, except chloro, hydroxyl melphalan, were similar under all reaction conditions. The relative second-order rate constant for nonenzymatic glutathionylation of the aziridinium intermediate was 7 times larger at pH 7.4 than at pH 6.5. GST was found to react only with the aziridinium intermediate formed from melphalan and to dissociate slowly from the resultant GST-product complex (dissociation half-life, 1 hr at pH 7.4 and 3.5 hr at pH 6.5). The kinetic parameter estimates found in this study can be used to make preliminary calculations of the impact that cellular phosphate, glutathione, and GST concentrations will have on the intracellular detoxication of melphalan.

Glutathione↗