Search PubMed⌕ Search

Biomedical subjects

I Kudo

Publications and source records attributed to I Kudo.

At least 181 records · Page 10Linked to original sources
PubMed1987

Activation of mouse peritoneal macrophages by synthetic glyceroglycolipid liposomes.

Liposomes composed of chemically synthesized glyceroglycolipids, such as 1,2-dipalmityl-[beta-cellobiosyl-(1'----3)]- glycerol (Cel-DAG), 1,2-dipalmityl-[beta-lactosyl-(1'----3)]-glycerol, or 1,2-dipalmityl-[beta-maltosyl-(1'----3)]-glycerol, were found to enhance protective immunity against transplantable tumor cells (sarcoma 180) in ICR mice. Peritoneal exudate cells prepared from mice treated in vivo with Cel-DAG showed cytostatic activity in vitro against the mouse leukemia cell line, EL-4. Adherent cells separated from this preparation showed similar activity. Peritoneal cells from polypeptone-injected mice acquired appreciable cytostatic activity when incubated in vitro in the presence of glyceroglycolipid liposomes. The adherent cell fraction alone showed rather weak cytostatic activity when pretreated with the glyceroglycolipids, and full activity was restored by supplementing with the nonadherent cell fraction. The ability of glycolipids to induce tumoricidal effects was affected by cholesterol content: with increasing cholesterol content, the activities decreased. Cholesterol-free glycolipid liposomes were taken more efficiently by macrophages than cholesterol-containing liposomes. Cholesterol modifies the surface property of glyceroglycolipid liposomes. Activation of macrophages is responsible for enhancement of protective immunity against tumor cells by injection of these glycolipids in vivo.

Animals↗
PubMed1987

Antitumor activity of synthetic alkylphospholipids with or without PAF activity.

1-O-Octadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET-18-OMe) has been reported to possess definite antitumor activity in vivo. Twenty-two alkyl lysophospholipid analogs were chemically synthesized, and their antitumor activity against mouse experimental tumors (Sarcoma 180, MM46, P388) was examined. Among them, 1-O-octadecyl-2-O-acetoacetyl-rac-glycero-3-phosphocholine was found to show antitumor activity similar to ET-18-OMe with less acute toxicity. Intravenous injection of the ET-18-OMe with sn-3 configuration retarded the subcutaneous growth of Sarcoma 180 cells effectively, while the growth inhibition by the sn-1 isomer was much less effective. This stereospecificity was similar to that observed in their activities as platelet-activating factor (PAF) agonists. The acetoacetyl compound, another PAF agonist, showed similar stereospecific antitumor action in vivo. These findings suggest that some alkyl lysophospholipids may activate host cells to a cytostatic stage against tumor cells in vivo through binding to a PAF receptor. Our preliminary results indicated that the responsible cells under these conditions might be primarily immature macrophages present in the bone marrow. No appreciable or even adverse stereospecificity was observed in the different sets of experiments where the activity of ET-18-OMe against MM46 tumor cells in vivo or the direct cytotoxicity against human promyelocytic leukemia HL-60 cells in vitro was examined. Under some conditions, the antitumor activity of ET-18-OMe in vivo may be revealed through direct cytotoxicity and/or modulation of the host defense system by "nonspecific" mechanisms. Some alkylphospholipids without PAF activity may also show antitumor activity through similar "nonspecific" mechanisms.

Animals↗
PubMed1987

Characteristics of phospholipid transacylase of Escherichia coli.

We have previously demonstrated the activity(ies) of phospholipid transacylase in Escherichia coli extract (Homma & Nojima (1982) J. Biochem. 91, 1093-1101), which catalyzed a new type of reaction of acyl transfer from diacylphospholipids to lysophospholipids. In this communication we report the specificities and characteristics of this enzyme activity. The activity catalyzed a reversible transfer of an acyl group between diacylphospholipids and lysophospholipids. The acyl group in the 1-position of the glycerol backbone was selectively transferred, and palmitic acid was the only fatty acid species transferred. Presumably, neutral lipids do not serve as substrates. The transacylase was firmly associated with the envelope fraction of E. coli. Neither potassium chloride nor urea was effective in solubilization of the activity and only about half of the activity was solubilized with Triton X-100. This observation was consistent with the equal distribution of the activity between the outer membrane and the inner membrane of E. coli. Functional aspects of this phospholipid transacylase are also discussed.

Acyltransferases↗
PubMed1987

Amino acid composition and NH2-terminal amino acid sequence of rat platelet secretory phospholipase A2.

The amino acid composition and partial NH2-terminal amino acid sequence of the phospholipase A2 secreted by stimulated rat platelets were determined. The most predominant amino acid in the phospholipase A2 was cysteine followed by lysine, suggesting that it is a basic one. This finding is consistent with its high affinity to a cation exchange column. The NH2-terminal 24 amino acids were found to be as follows: X-Leu-Leu-Glu-Phe-Gly-Gln-Met-Ile-Leu-Phe-Lys-Thr-Gly-Lys-Arg-Ala-Asp- Val-Ser-Tyr-Gly-Phe-Tyr-Gly- The enzymes contains 5Phe, 8Met, 9Ile, 24Tyr, and 25Gly residues, all of which are conserved in the sequenced pancreatic phospholipase A2. This is the first report of the tentative characterization of a eukaryotic phospholipase A2, the cellular source of which is known, i.e., it does not originate from a venom or the pancreas.

Amino Acid Sequence↗
PubMed1987

Purification and characterization of extracellular phospholipase A2 from peritoneal cavity of caseinate-treated rat.

Peritoneal exudate produced in rat injected with caseinate contained extracellular phospholipase A2. The activity required Ca2+ ion and had a pH optimum of 9 (Chang, H.W., Kudo, I., Hara, S., Karasawa, K., & Inoue, K. (1986) J. Biochem. 100, 1099-1101). This phospholipase A2 was purified about 14,000-fold to near homogeneity by the sequential use of column chromatography on Sephadex G-75, Toyopearl HW-65, and TSK ODS-120T reverse-phase HPLC. The final preparation showed a single protein band on SDS-polyacrylamide gel electrophoresis, and its molecular weight was estimated to be approximately 13,500. The enzyme hydrolyzed phosphatidylethanolamine (PE) and phosphatidylserine (PS) more effectively than phosphatidylcholine (PC). When 1-acyl-2-[1-14C]inoleoyl-sn-glycero-3-phospholipids were used as a substrate, the apparent Km values were 0.027 mM with PE, 0.032 mM with PS, and 0.1 mM with PC, and the Vmax values were 105 mumol/min/mg with PE, 71 mumol/min/mg with PC. The enzyme activity was inhibited by p-bromophenacyl bromide, dithiothreitol, and mepacrine. The amino acid sequence of the NH2-terminal portion and the amino acid composition of the purified enzyme were determined. They were different from those of rat pancreatic phospholipase A2, but very similar to those of phospholipase A2 secreted from rat platelets.

Amino Acids↗
PubMed1987

Lipids of human promyelocytic leukemia cell HL-60: increasing levels of ether-linked phospholipids during retinoic acid-induced differentiation.

Cells of the human promyelocytic leukemia cell line HL-60 as well as HL-60 granulocytes induced in vitro by retinoic acid were examined for lipid composition. One of our original aims was to clarify how human granulocyte (differentiated HL-60 cells) synthesized enough precursors of lipid mediators, such as prostaglandins and/or platelet activating factor. Comparison studies yielded the following results. 1) After granulocyte differentiation, total phospholipid of HL-60 cells decreased to about 70% of that of untreated cells, while the content of triglyceride increased to about 200% of the original level. 2) The subclass composition of ethanolamine-containing glycerophospholipid was greatly altered during differentiation; 1-alkenyl-2-acyl glycerophosphoethanolamine (GPE) increased to 166% of that in the untreated cells, while 1,2-diacyl GPE decreased to 46% of the original value. The resultant profile became very similar to that of human peripheral polymorphonuclear leukocytes. 3) During differentiation, the amount of arachidonic acid stored in both phospholipid and triglyceride of retinoic acid-treated HL-60 cells significantly increased. Its distribution was also modified; arachidonic acid in 1,2-diacyl GPE decreased to 63%, while those of 1-alkenyl-2-acyl GPE, choline-containing glycerophospholipids, and phosphatidylinositol increased to 169, 154, and 153%, respectively. These results suggested that the regulatory mechanism of lipid turnover in HL-60 cells was modified during retinoic acid-induced granulocyte differentiation. The alterations were not enough to explain fully the capability of differentiated HL-60 cells to produce lipid mediators upon stimulation, but they were probably one of the factors that regulate these reactions.

Cell Differentiation↗
PubMed1987

Two affinity immunoelectrophoretic methods for studying collagen interaction with von Willebrand factor antigen.

Two new immunoelectrophoretic methods are described for studying the interaction of collagen fibrils with von Willebrand factor antigen (vWF: Ag). In the first, the sample was electrophoresed through a collagen-agarose wedge into an antibody-agarose area, and immunoprecipitin lines was detected by staining. Different immunoprecipitin patterns were obtained with the vWF: Ag of normal plasma, commercial FVIII preparations, and von Willebrand disease (vWD) type IIa plasma as the result of collagen binding of vWF: Ag. In the other method, the sample was electrophoresed into agarose for preliminary separation of forms, followed by migration in the second dimension through a collagen spacer gel into an antibody-agarose area. This method demonstrated preferential binding of high molecular weight forms of vWF: Ag in normal plasma and slight binding of the lower molecular weight forms of antigen found in vWD type IIa plasma. The affinity wedge method is a convenient general method for finding quickly a useful concentration of affinity reagent.

Antigens↗
PubMed1986

Effect of fibronectin and von Willebrand factor on the adhesion of human fixed washed platelets to collagen immobilized beads.

The adhesion of human fixed washed platelets (FWP) to collagen was measured using collagen immobilized beads. The addition of normal plasma or severe von Willebrand disease (VWD) plasma to FWP decreased the adhesion, suggesting the presence of some inhibitors of platelet adhesion in human plasma. Although the adhesion of FWP in severe VWD plasma was not different from that of FWP in normal plasma, the addition of purified von Willebrand factor (vWF, 1-2 mu/ml ristocetin cofactor) to FWP in buffer increased the FWP adhesion at higher flow rates, and the percent of adhesion in the absence of vWF was 10% (collagen 500 micrograms) and 30% (collagen 1,000 micrograms) of that in the presence of vWF at 10 ml/min. The enhancing effect of the vWF on FWP adhesion was also observed by pretreatment of the collagen column with vWF suggesting the important role of bound vWF to the collagen; adhesion 72% to the collagen column (1,600 micrograms) treated with vWF and 16% to the collagen column without the pretreatment at 10 ml/min. The promoting effect of vWF was also present in some commercial factor VIII preparations which had no large or intermediate multimers of vWF antigen. The adhesion of FWP was inhibited by fibronectin (FN) and the binding of ristocetin cofactor (vWF:RCo) to collagen fiber was also inhibited by FN; bound vWF:RCo to 50 micrograms/ml collagen in the absence or presence of 125 micrograms/ml FN were 60% and 8% respectively. It is suggested that vWF, even small multimer of vWF:Ag, is involved in the initial platelet-collagen interaction at high flow rates, while plasma FN acts as one of anti-adhesion factor.

Adult↗
PubMed1986

Extracellular phospholipase A2 activity in peritoneal cavity of casein-treated rats.

An extracellular phospholipase A2 was detected in the peritoneal cavity of rats injected intraperitoneally with casein. This activity required Ca2+ ion and had a pH optimum of 9. The increase of phospholipase A2 activity in the peritoneal fluid as a function of time roughly paralleled the increase in the number of polymorphonuclear (PMN) leukocytes found in the peritoneal cavity. Phospholipase A2 activity was also observed in rat PMN homogenates, and its characteristics were similar to those of the enzyme found in cell-free peritoneal fluid fraction. PMN leukocytes may release non-lysozomal phospholipase A2 into the extracellular space as 'inflammation reactions' proceed.

Animals↗