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Biomedical subjects

T Sakagami

Publications and source records attributed to T Sakagami.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Frequency of food intake of dentulous and complete denture wearers].

The study was carried out on 1466 subjects, whose ages ranged from 20 to 80 years of age, of whom 1181 were dentulous and 285 were complete dentures. We studied the frequency with which the 1466 cases partook of food. The results were as follows: 1) Ingested foods were classified into 10 groups along with the frequency with which they were ingested on a yearly seasonal basis. Food groups were classified as follows: vegetables, grain, sea food, beans, meat, seaweed, potatoes, fruits, etc. 2) The Ingested foods of the dentulous group were similar to those of the complete denture wearers. 3) In all age groups the foods most ingested were: steamed rice, wakame, tofu, bread, scallions, Japanese omelette, and tomatoes. 4) The younger subjects (20 to 39 years) statistically ate significantly lower amounts of steamed rice than did the older age groups. 5) The younger generation ate more meat, while the older groups ate more sea food.

Adolescent↗
PubMed1989

Income maximizing in concurrent interval-ratio schedules.

Three mice chose between concurrent variable-ratio variable-interval schedules to produce a warm air stream while they were housed in a cold chamber. Across conditions, the duration of the warm air stream was varied between 10 and 80 s and was equal for both schedules. Preference for the VI schedule covaried with reinforcer duration as predicted by maximizing accounts of choice.

Journal Article↗
PubMed1986

Phospholipid metabolism in bile duct-ligated rat plasma and erythrocytes.

Incorporation of [32P]orthophosphate into phosphatidylcholine, lysophosphatidylcholine and molecular species of phosphatidylcholine in vivo was observed in liver, plasma and erythrocytes of bile duct-ligated or sham-operated rats. Both the amount and radioactivity of dienoic species of phosphatidylcholine in all tissues examined increased in bile duct-ligated rats as compared to sham-operated rats. The experiments in vivo and in vitro showed that the ratio of lysophosphatidylcholine to phosphatidylcholine transferred to erythrocytes from plasma in sham-operated rats was much higher than that in bile duct-ligated rats. It is suggested that one of the mechanisms by which abnormal erythrocytes appear might be explained by the facilitated and direct transfer of phosphatidylcholine, which is caused by the interaction of erythrocytes with bile acid in bile duct-ligated rat plasma.

Animals↗
PubMed1984

A fluorimetric determination of the activity of glycolipid transfer protein and some properties of the protein purified from pig brain.

The fluorimetric method of Correa-Freire et al. (Correa-Freire, M.C., Barenholz, Y. and Thompson, T.E. (1982) Biochemistry 21, 1244-1248) to measure glucosylceramide transfer between phospholipid bilayers has been applied to the determination of the activity of glycolipid transfer protein purified from pig brain. The transfer of pyrene-labeled galactosylceramide (PyrGalCer) from donor to acceptor vesicles was measured by a decrease in the intensity ratio of eximer (E) to excited monomer (M). A sensitive determination of the glycolipid transfer activity is possible by the fluorimetric method without separation of the donor and acceptor vesicles. The newly developed fluorimetric assay of glycolipid transfer protein was used to study the effects of N-ethylmaleimide, HgCl2 and sugars on the transfer activity. The treatment with N-ethylmaleimide inactivated the activity to about 40%. The activity was almost completely inactivated by the treatment with HgCl2. Monosaccharides and methyl-alpha-D-glucoside had no inhibitory effect on the transfer activity. A marked and immediate drop of the E/M ratio was observed by the addition of glycolipid transfer protein to vesicles containing PyrGalCer at a protein-to-PyrGalCer molar ratio of 1.56:1. The result suggests a complex formation of glycolipid transfer protein with PyrGalCer.

Animals↗
PubMed1983

Experimental biliary obstruction of rat. Initial changes in the structure and lipid content of erythrocytes.

The bile duct was ligated and the resulting changes in the plasma and erythrocyte lipid composition and in the shape of erythrocytes were observed. Electron microscopy at 8th hour after ligation revealed the appearance of spur cells, and on the 7th day target cells began to be observed. The appearance of spur cells was considered to be a reflection of abrupt increases in bile acid and bilirubin levels in the plasma. The conversion of spur cells to target cells which was observed was accompanied by increased levels of cholesterol and phosphatidylcholine in the erythrocytes. Plasma phosphatidylcholine and cholesterol levels were increased immediately after the commencement of ligation. On the other hand, erythrocyte phosphatidylcholine and cholesterol levels only gradually increased when compared to those in plasma, and the maximum value was observed from the 5th to the 7th day. The fatty acid composition of the increased plasma phosphatidylcholine after ligation resembled that of phosphatidylcholine in bile. On the other hand, the fatty acid composition of erythrocyte phosphatidylcholine changed remarkably between the 1st and 3rd days after bile duct ligation. These changes were also reflected by those of phosphatidylcholine in bile. These results led to the conclusion that the appearance of target cells observed in the present study was due to the accumulation of erythrocyte lipids which derived from bile. This is the first report on experimentally induced target cells and the mechanism for their appearance that seems applicable for humans.

Animals↗
PubMed1983

Ecto-5'-nucleotidase does not catalyze vectorial production of adenosine in the perfused rat liver.

From the results obtained in perfused rat hearts, Frick and Lowenstein proposed that ecto-5'-nucleotidase catalyzes a vectorial reaction in which AMP hydrolysis is accompanied by transfer of adenosine across the cell membrane (Frick, G.P., and Lowenstein, J.M. (1978) J. Biol. Chem. 253, 1240-1244). We have examined by the use of perfused rat livers, the uptake mechanism of adenosine generated from AMP by ecto-5'-nucleotidase. Recirculating perfusion of rat livers was performed with a buffered saline containing [2-3H]AMP at an initial concentration of 5 microM. One-half of the [2-3H] AMP was dephosphorylated by 0.8 min of perfusion; less than 13% of the radioactivity of hydrolyzed [2-3H] AMP was located in [2-3H]adenosine plus [2-3H]inosine appearing in the perfusate. Addition of 6-[(4-nitrobenzyl)thio]-guanosine, an inhibitor of the nucleoside transport system, at 120 microM to the perfusate caused a 3.9-fold increase in the amount of the [2-3H]AMP-derived 3H-nucleosides appearing in the perfusate. Moreover, in a perfusion in which uridine was added to the perfusate at 2.6 mM to compete with the [2-3H] AMP-derived [2-3H]adenosine for the nucleoside transport system, more than 87% of the radioactivity of hydrolyzed [2-3H]AMP was located in [2-3H]adenosine appearing in the perfusate; the result indicates that the uridine added to the perfusate efficiently trapped the [2-3H]adenosine formed from [2-3H]AMP. These results support an uptake mechanism of the AMP-derived adenosine in which the adenosine formed by ecto-5'-nucleotidase in the blood-sinusoidal plasma membrane of hepatocytes, is taken up by the nucleoside transport system located at the plasma membrane side by side with ecto-5'-nucleotidase. The results therefore indicate that the ecto-5'-nucleotidase of hepatocytes does not catalyze vectorial production of adenosine, in contrast to the previous report on perfused rat hearts.

5'-Nucleotidase↗
PubMed1982

Effect of prostaglandin E1 and polyphloretin phosphate on hemolysis of human erythrocytes.

Prostaglandin E1 was found to reduce the hemolysis rate induced by various factors, such as frequent shakings, treatment with hog pancreatic phospholipase A2, the addition of active oxygens generated by a xanthine oxidase system, and the addition of a prostaglandin antagonist, polyphloretin phosphate (PPP). Prostaglandin E1 was found to act on the erythrocytes in such a way as to cause the phospholipids in the membrane to become more compactly arranged thus becoming less susceptible to the attack of hemolytic reagents. It was observed that the extents of hemolysis were different between erythrocytes from males and females and furthermore, it was shown that prostaglandin E1 clearly reduced the rate of hemolysis of erythrocytes from males, while, in females, the effects of prostaglandin E1 were less than those in erythrocytes from males.

Adult↗
PubMed1981

A simple and effective method for hemolysis with a hypoxanthine-xanthine oxidase system and alteration of erythrocyte phospholipid composition during the hemolysis.

A very rapid hemolysis was found to be caused by active oxygen species produced by a hypoxanthine-xanthine oxidase system with very low concentrations of hypoxanthine. The addition of superoxide dismutase or catalase inhibited the hemolysis, indicating that O2- and H2O2 participate in this system. The extent of erythrocyte hemolysis was found to depend on the sex of the human donor. The change in phospholipid composition before and after hemolysis in human erythrocytes from donors of each sex was compared by thin layer chromatography. A significant decrease in phosphatidylethanolamine content and a concomitant increase in altered phospholipid fraction were observed in erythrocytes from male donors, suggesting that these erythrocytes were easily attacked by active oxygen species to produce modified phosphatidylethanolamine.

Adult↗
PubMed1981

Phosphatidylcholine and phosphatidylinositol exchange proteins in pig liver.

The pH 5.1 supernatant fraction of pig liver homogenate stimulated the transfer of [32P]phosphatidylcholine and [32P]phosphatidylinositol from donor liposomes to acceptor liposomes. Purification of the proteins which catalyzed the exchanges yielded five partially purified preparations. A phospholipid exchange protein was purified 63-fold in one of the preparations and the protein was found to be specific for phosphatidylcholine exchange. The molecular weight and isoelectric point of the protein was estimated to be 19,000 and 5.6, respectively. The other four preparations contained partially purified phospholipid exchange proteins which catalyzed the exchanges of phosphatidylinositol as well as phosphatidylcholine. The molecular weights and the isoelectric points of the phosphatidylcholine-phosphatidylinositol exchange proteins were estimated to be 19,000 and 4.7, and 19,000 and 4.8 for the proteins in the second preparation, and 21,000 and 4.5 for the protein in the third preparation. These parameters in the other two preparations were tentatively estimated to be 24,000 and 5.6, and 18,000 and 4.6. Neither sulfhydryl-binding reagents nor trypsin digestion inactivated the activity of the phosphatidylcholine specific exchange protein. Sulfhydryl-binding reagents and trypsin digestion inactivated all the phosphatidylinositol exchange activities of the partially purified exchange proteins and the phosphatidylcholine exchange activities which were presumably associated with the phosphatidylinositol exchange proteins.

Animals↗
PubMed1981

Measurement of isoelectric points of phospholipid exchange proteins by gel isoelectric focusing.

A method of the estimation of isoelectric points of phospholipid exchange proteins is described. The phospholipid presumably bound to a phospholipid exchange protein was replaced with [3H]phosphatidylcholine of a high specific radioactivity by an incubation of the protein with liposomes containing the labeled lipid and dimannosyl diglyceride. After the incubation, a major portion of the liposomes was separated from the protein by an affinity of the liposomes to concanavalin A-Sepharose 2B. The isoelectric point of the protein was measured by gel isoelectric focusing of the protein, which was located by tritium radioactivity of the bound [3H]phosphatidylcholine. The method was used to measure isoelectric points of partially purified phospholipid exchange proteins in pig liver.

Carrier Proteins↗
PubMed1979

Phosphatidylcholine and phosphatidylinositol exchange proteins in rat liver.

The phospholipid exchange proteins in rat liver that stimulate the transfer of phosphatidylcholine and phosphatidylinositol between membranes were separated into three fractions and partially purified by acid pH precipitation, gel filtration on Sephadex G-75, and ionexchange chromatography on DEAE-cellulose and CM-cellulose. Throughout the steps of the purification, both the phosphatidylcholine exchange activity and the phosphatidylinositol exchange activity were measured by a liposome-liposome assay system, which used concanavalin A in the separation of donor and acceptor liposomes. One of the fractions was purified 172-fold and stimulated the phosphatidylcholine exchange but not the phosphatidylinositol exchange. The other two fractions were active in the stimulation of the phosphatidylinositol exchange as well as the phosphatidylcholine exchange and were purified 62-fold and 58-fold over the cell supernatant fraction with respect to the phosphatiylinsitol exchange activity. These two fractions stimulated the transfer of phosphatidylinositol from donor liposomes to acceptor liposomes initially deficient in this phospholipid.

Animals↗
PubMed1978

A new assay system of phospholipid exchange activities using concanavalin A in the separation of donor and acceptor liposomes.

A new assay system of phospholipid exchange activities is described. The exchange activities were quantitated by measuring the stimulation of phospholipid transfer between two separate populations of liposomes, which contained, as the major constituents, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, sphingomyelin, and cholesterol in molar ratios of 6 :2 : 1: 1: 5. One population of the liposomes was made reactive to concanavalin A by the incorporation of 1.8 mol% alpha-D-mannosyl-(1 leads to 3)-alpha-D-mannosyl-sn-1, 2-diglyceride from Micrococcus lysodeikticus. The concanavalin A-reactive liposomes, a phospholipid donor, were doubly labelled with [6-3H] galactosylglucosyl ceramide and that class of 32P-labelled phospholipids whose exchange was being measured. The 3H-labelled glycolipid served as a non-exchangeable reference marker. The other population of the liposomes, a phospholipid acceptor, was concanavalin A nonreactive. These two populations of liposomes were incubated with the cytosol protein of rat liver in a total volume of 0.2 ml. After the incubation, two different procedures were used to separate the two liposomal populations. In one procedure concanavalin A was added to agglutinate the reactive liposomes; the flocculated lectin . liposome complex was separated from the non-reactive liposomes by brief centrifugation. In the other procedure the reactive liposomes were trapped by binding to concanavalin A covalently coupled to Sepharose 2B; the complex was separated from the non-reactive liposomes by filtration through a filter paper under suction. In both assay procedures the amount of phospholipid transferred from the donor to the acceptor liposomes was calculated from the decrease of 32P/3H ratio of the concanavalin A-reactive liposomes during the incubation. By the assasy system it is possible to determine phosphatidylcholine and phosphatidylinositol exchange activities in 100 micrograms of rat liver cytosol protein.

Animals↗
PubMed1978

Separation and purification of phospholipid exchange proteins in rat small intestinal mucosa.

The cytosol fraction of rat small intestinal mucosa stimulated the transfer of [32P]phosphatidylcholine and [32P]phosphatidylinositol from donor liposomes to acceptor liposomes. The proteins which catalyzed the exchanges were separated into three fractions by gel filtration on a Sephadex G-75 column and chromatography on DEAE-cellulose and CM-cellulose. One of the fractions was purified 340-fold and stimulated phosphatidylcholine exchange but not phosphatidylinositol exchange. The other two fractions were active in the stimulation of phosphatidylcholine exchange as well as phosphatidylinositol exchange. These two fractions were purified 35-fold and 44-fold over the cytosol fraction with respect to the phosphatidylinositol exchange activity.

Animals↗