The Journal of laboratory and clinical medicine
-
An iron chelator of low water solubility, HBED, has been encapsulated in the lipid bilayers of unilamellar and multilamellar liposomes. The effectiveness of liposome-encapsulated HBED for removing excess iron burden from the RE system of the mouse liver (i.e., Kupffer cells) has been compared to that of the most commonly used iron chelator, DF, a water-soluble drug. ⋯ Our results have thus demonstrated that liposomes could be very useful as injection vehicles for metal chelators that are not readily soluble in water. HBED is also demonstrated to be far superior to DF, the iron chelator of choice for therapy of transfusional iron overload.
-
Adrenal E synthesis is thought to require locally high glucocorticoid concentrations to induce the enzyme PNMT for methylation of NE. By suppressing ACTH secretion, exogenous glucocorticoids may limit secondarily adrenal medullary E production. AG, a competitive inhibitor of adrenal steroidogenesis, also may limit adrenal medullary E synthesis. ⋯ C recipients also had suppressed resting and early reflex (p < 0.01) NE secretion. These results are consistent with the functional importance of the intimate anatomic relationship between the adrenal cortex and medulla. A defect in E-related adrenergic reflexes may occur in patients treated similarly to these experimental groups.
-
The influence of free fatty acids (FFA's) on the albumin binding of bilirubin was studied in vitro in the plasma of infants with neonatal hyperbilirubineamia and in solutions employing crystalline albumin to which bilirubin and FFA (oleic acid) were added. The bilirubin saturation index (SI) was utilized to distinguish between that fraction of bilirubin bound at the primary (high-affinity) site of albumin and bilirubin bound at secondary sites from which it is easily dissociated by salicylate. The relative saturation of albumin with bilirubin was also measured by addition of salicylate to whole blood samples where bilirubin was also measured by addition of salicylate to whole blood samples where bilirubin dissociated from the albumin could be sequestered by the red cells. ⋯ At molar ratios of FFA to albumin (2:1 to 4:1), the FFA's compete with bilirubin for binding at the high-affinity site so that a significant portion of the bilirubin is transported at secondary sites, making it susceptible to displacement by water-soluble organic anions. At high molar ratios (greater than 5:1) FFA's compete with bilirubin for albumin binding at the secondary sites as well. In contrast to crystalline albumin where the first two molar equivalents of FFA do not influence the binding of bilirubin to albumin, all FFA concentrations in hyperbilirubinemic plasma reduce the affinity of albumin for bilirubin at its high-affinity site even though there is a molar excess of albumin over bilirubin.
-
Suspensions of platelet-rich plasma (PRP) or gel-separated platelets (GSP) can be used to evaluate clot retraction subsequent to platelet aggregation and fibrin formation. PRP (200,000 per cubic millimeter) or GSP (200,000 or 100,000 per cubic millimeter) are diluted 1:10 (PRP) or 1:8 (GSP) in phosphate buffer, pH 7.4, and clotted with a high concentration (2.5 U. per milliliter) of thrombin. Human fibrinogen (25 mg. per cent) is added to GSP prior to dilution. ⋯ High concentrations of PGE1 (to 6 x 10(-6) M) do not inhibit aggregation of GSP, fibrin formation, or platelet-fibrin interaction induced by 2.5 U. per milliliter of thrombin. In contrast, PGE1 concentrations as low as 1.5 to 3.0 x 10(-8) M inhibit clot retraction in both the dilute PRP and GSP systems. Thus, using dilute PRP or GSP the effects of platelet aggregation inhibitors on clot retraction can be determined independently of effects on platelet aggregation.