Yoshimitsu Shimamori

Mutual displacement interactions in the binding of two drugs to human serum albumin by frontal affinity chromatography

A continuous frontal analysis chromatographic method was developed for studying the simultaneous binding of two drugs or ligands with an immobilized macromolecule. The usefulness of this method was demonstrated in the interactions of sulphamethizole and salicylic acid with human serum albumin (HSA). The mutual inhibitory effect on the binding of one drug of the presence of the other was directly shown to be due to displacement of the bound drug from HSA by the other. On the basis of a double-reciprocal plot analysis, these two drugs are interpreted as competing for the same primary binding sites.

Binding capacities of human serum albumin monomer and dimer by continuous frontal affinity chromatography.

Human serum albumin monomer and dimer obtained by fractionation of a commercial preparation were immobilized on CH-Sepharose 4B by covalent coupling. For salicylic acid, warfarin, phenylbutazone, mefenamic acid, sulphamethizole and sulphonylureas, the binding capacities of the monomer and dimer were compared by continuous frontal affinity chromatography. The salicylate-binding capacities of both monomer and dimer were essentially retained upon immobilization. For these drugs, the dimer showed only about 10-30% less capacity per monomeric unit than that of the monomer, the reduction being associated for most drugs with the intrinsic binding constant rather than with the number of binding sites.

Human placental dipeptidyl aminopeptidase III: hydrolysis of enkephalins and its stimulation by cobaltous ion.

The degradation of enkephalin and related peptides by highly purified dipeptidyl aminopeptidase III (EC 3.4.14.4) was studied. The enzyme releases the N-terminal dipeptide units from substrates greater in length than the tetrapeptide. The enzyme exhibits an optimum of pH 7.5, Km of 81 microM and Vmax of 0.043 mumole/min for Leu-enkephalin. Its activity was markedly stimulated by Co2+, with both the Km and Vmax being increased. Among the enkephalin-related peptides examined, des-Tyr1-Leu-enkephalin was the most rapidly hydrolyzed with Co2+, but only slight stimulation was observed with Co2+.

Aminopeptidases in human retroplacental sera: Purification and characterization of two enzymes

Ten different maternal serum samples were analyzed for the hydrolysis of S-Bz-Cys-pNA (substrate for CAP) and Ala-pNA. The results showed clear differences in the activities in individual sera. Similar S-Bz-Cys-pNA hydrolysis activity was detected for all sera. However, Ala-pNA hydrolysis activity differed remarkably. Serum exhibiting low Ala-pNA hydrolysis activity contained only CAP, and that exhibiting high Ala-pNA hydrolyzing activity contained CAP and AAP. The two aminopeptidases were independently purified to a homogeneous state through the same purification procedures and some of their biochemical properties were compared. The enzymes were quite different with respect to molecular mass, the substrate specificities for some aminoacyl-pNA substrates, and the effects of inhibitors. Among various natural peptides tested for hydrolysis, the enzymes hydrolyzed Met-enkephalin most rapidly, but their modes of action were different. Furthermore, only CAP degraded oxytocin and AAP exhibited a high kinin-converting activity.

Purification and characterization of thiol aminopeptidase from the cytosolic fraction of human placenta

A thiol-dependent aminopeptidase was purified from the cytosolic fraction of human placenta. The purified enzyme consisted of a single polypeptide chain with a mol wt of 95,000. The enzyme was most active in the neutral region with Ala-pNA as substrate, and the activity was increased about 20-fold in the presence of some -SH compounds. The results of substrate specificity studies indicated that the enzyme hydrolyzes bonds involving the amino groups of neutral and basic amino acid residues. However, higher thiol-dependent activity was only detected with neutral ones. The enzyme was strongly inhibited by microbial aminopeptidase inhibitors, puromycin, o-phenanthroline, and sulfhydryl reactive-reagents. As to several naturally occurring peptides tested, the enzyme showed N-terminal Tyr-releasing activity toward enkephalins and kinin-converting activity.

Activated carbon beads for the removal of highly albumin-bound species.

Activated carbon beads in which 5% activated carbon powder was embedded in 4% agarose were prepared by the emulsion technique. The column of the beads was demonstrated to effectively remove salicylic acid, warfarin, and long-chain fatty acids from solutions containing albumins by either zonal or frontal analysis under the condition of 0.1 M NaCl, pH 3.0 (HCl). The beads were also demonstrated to purify a commercial human serum albumin preparation from residual fatty acids. The beads would be of value in many biochemical purification processes in which activated carbon is employed.

Purification and characterization of a membrane-bound neutral endopeptidase from human placenta

A membrane-bound neutral endopeptidase which hydrolyzes Suc-(Ala)3-pNA to succinyl dialanine and Ala-pNA has been purified from human placenta. The enzyme was solubilized from membranes with DOC and papain, and was purified about 5000-fold by successive chromatographies on Sephadex G-200, DEAE-Sephacel, butyl-Toyopearl 650, and Sephacryl S-300. It was found to be homogeneous on SDS-polyacrylamide gel electrophoresis and to have a molecular weight of about 70,000. It was strongly inhibited by phosphoramidon, thiorphan, and metal-chelating agents, but was not affected by most other protease inhibitors. These findings indicate that it can be classified as a phosphoramidon-sensitive neutral endopeptidase. With biologically active peptides as substrates, the enzyme preferentially cleaved the bonds at the amino side of hydrophobic amino acid residues. The physiological significance of this enzyme is discussed with reference to the placental barrier.

電子カルテ上への「添付文書情報提供システム」の構築とその運用に関する研究

To promote the appropriate use of pharmaceuticals and to prevent side effects, physicians need package inserts on medicinal drugs as soon as possible. A medicinal drug information service system was established for electronic medical records to speed up and increase the efficiency of package insert communications within a medical institution. Development of this system facilitates access to package inserts by, for example, physicians. The time required to maintain files of package inserts was shortened, and the efficiency of the drug information service increased. As a source of package inserts for this system, package inserts using a standard generalized markup language (SGML) form were used, which are accessible to the public on the homepage of the Organization for Pharmaceutical Safety and Research (OPSR). This study found that a delay occurred in communicating revised package inserts from pharmaceutical companies to the OPSR. Therefore a pharmaceutical department page was set up as part of the homepage of the medical institution for electronic medical records to shorten the delay in the revision of package inserts posted on the medicinal drug information service homepage of the OPSR. The usefulness of this package insert service system for electronic medical records is clear. For more effective use of this system based on the OPSR homepage pharmaceutical companies have been requested to provide quicker updating of package inserts.

Investigation of cost and medical service fee for pharmaceutical management in home medical care

Due to the evolvement of the aged society and the steep rise in medical costs, the environment encircling the medical care industry has been changing remarkably. For this reason, it has become both necessary and fundamental for a community pharmacist to participate in home medical care through the pharmaceutical management service. We have studied the associated costs and medical service fees for pharmaceutical management in home medical care. The costs and medical service fees were calculated based on the pharmaceutical management service data collected during the three years from November 1998 to October 2001. As a result, the medical service fees were calculated using the old system which lasted until March 2002. Calculations using this system took into account 550 points per visit, up to two visits per month. Under the new system which started in April 2002, the number of visits taken into account is four times a month, 500 points for the first visit, 300 points from the second through to the forth visit. Then, we simulated a break-even point (BEP). It is clear that it is difficult for any community pharmacy to be specialized in home medical care. In order for the pharmacist to actively participate in home medical care in the future, it is necessary to further improve the system.