K Shirai

Chiba University, Chiba-shi, Chiba-ken, Japan

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Publications (32)144.87 Total impact

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    ABSTRACT: The patient was a 74-year-old woman who had been obese since age 18. Her obesity was refractory to dietary manipulation. She had been suffering from increasing dyspnea for several months and eventually could not even move. She was admitted to a hospital and diagnosed as having heart failure. Although her cardiac function recovered with medical treatment, her symptoms did not improve. The patient was then sent to our hospital. On admission, her height and weight were 149 cm and 81.9 kg, respectively, yielding a body mass index (BMI) of 36.6 kg/m2. Arterial blood gas analysis in room air revealed hypoxemia and an apnea index of 27 per hour. She was given a daily 500-1000 kcal diet. After four months of treatment, her weight decreased to 65 kg with a BMI of 29.3 kg/m2. Weight reduction together with the usage of progesterone-derivatives resulted in marked improvement of sleep apnea. The apnea index decreased to 3/h and arterial blood gas values normalized. This patient seemed to have suffered from both obesity hypoventilation syndrome and sleep apnea syndrome. Improvement of respiratory function was achieved through relief of airway obstruction and weight reduction, with activation of the respiratory center due to progesterone treatment.
    Nippon Ronen Igakkai Zasshi Japanese Journal of Geriatrics 01/1993; 29(12):965-71. DOI:10.3143/geriatrics.29.965
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    ABSTRACT: Nodular xanthomas on both elbows and a streak-like xanthoma on the intergluteal area developed in a 4-year-old girl with type IIa hyperlipoproteinemia. She had no disease associated with secondary hypercholesterolemia and no family history of hypercholesterolemia. Her xanthomas regressed under fat restriction diet and cholestyramine therapy. She was diagnosed as having pseudohomozygous type II hyperlipoproteinemia. The low-density lipoprotein (LDL) receptor activities of her cultured fibroblasts in terms of binding, internalization and degradation rate of LDL were normal. These results are consistent with a new syndrome of pseudohomozygous type II hyperlipoproteinemia and suggest that the mechanism of hypercholesterolemia, which induced xanthoma, differs from familial hypercholesterolemia.
    Dermatologica 02/1991; 182(2):94-7. DOI:10.1159/000247753
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    ABSTRACT: To clarify the possibility that brain microvessels could utilize very low density lipoprotein (VLDL)-triglyceride, the hydrolysis of [14C] triolein in VLDL by rat brain microvessels was examined. The rat brain microvessels were prepared under microscopy. In the homogenate, triolein hydrolyzing activity was observed only in the presence of apolipoprotein C-II. That activity was diminished by the addition of 1 M NaCl. [14C] triolein incorporated in VLDL was hydrolyzed time- dependently. These results suggested that there exists lipoprotein lipase in brain microvessels and the brain can utilize VLDL triglyceride as a source of fatty acids.
    The Tohoku Journal of Experimental Medicine 09/1986; 149(4):449-50. DOI:10.1620/tjem.149.449 · 1.28 Impact Factor
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    ABSTRACT: The influence of glycyrrhizin on the effect of phospholipase A2 on lysosomes was studied. Treatment of rat liver lysosomes with venom phospholipase A2 caused release of acid phosphatase. This release of acid phosphatase was inhibited by 0.1 mM glycyrrhizin. Glycyrrhizin also inhibited acid phospholipase A2 with pH optimum of 4.5, which is thought to be present in the lysosomal membrane. These results suggest that glycyrrhizin stabilizes lysosomes by inhibiting phospholipase A2 activity in the lysosomal membrane.
    The American Journal of Chinese Medicine 02/1986; 14(3-4):131-7. DOI:10.1142/S0192415X86000211 · 2.63 Impact Factor
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    ABSTRACT: Studies were made on the effect of phospholipase A2 on the stability of arterial wall lysosomes, and the influence of glycyrrhizin on this effect. Lysosomal phospholipase A2 activity was found to be increased in the aorta of hypercholesterolemic rats. Treatment of the lysosomal fraction of the arterial wall with venom phospholipase A2 resulted in release of acid phosphatase, and addition of glycyrrhizin (0.1 mM) inhibited this release. Lysosomal phospholipase A2 in the arterial wall was also inhibited dose-dependently by glycyrrhizin. These results suggest that lysis of lysosomes was due to increase in phospholipase A2 activity, and that glycyrrhizin stabilized the lysosomes by inhibiting phospholipase A2 activity.
    The American Journal of Chinese Medicine 02/1986; 14(3-4):138-44. DOI:10.1142/S0192415X86000223 · 2.63 Impact Factor
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    ABSTRACT: The metabolism of the linolenic acid family (n-3) of fatty acids, e.g., linolenic, eicosapentaenoic, and docosahexaenoic acids, in cultured smooth muscle cells from rabbit aorta was compared to the metabolism of linoleic and arachidonic acids. There was a time-dependent uptake of these fatty acids into cells for 16 hr (arachidonic greater than docosahexaenoic, linoleic, eicosapentaenoic greater than linolenic), and the acids were incorporated mainly into phospholipids and triglycerides. Eicosapentaenoic and arachidonic acids were incorporated more into phosphatidylethanolamine and phosphatidylinositol plus phosphatidylserine and less into phosphatidylcholine than linolenic and linoleic acids. Docosahexaenoic acid was incorporated into phosphatidylethanolamine more than linolenic and linoleic acids and into phosphatidylinositol plus phosphatidylserine less than eicosapentaenoic and arachidonic acids. Added linolenic acid accumulated mainly in phosphatidylcholine and did not decrease the arachidonic acid content of any phospholipid subfraction. Elongation-desaturation metabolites of linoleic acid did not accumulate. Cells treated with eicosapentaenoic acid accumulated both eicosapentaenoic and docosapentaenoic acids mainly in phosphatidylethanolamine and the arachidonic acid content was decreased. Added docosahexaenoic acid accumulated mainly in phosphatidylethanolamine and decreased the content of both arachidonic and oleic acids. The following conclusions are drawn from these results. The three n-3 fatty acids are utilized differently in phospholipids. The arachidonic acid content of phospholipids is reduced by eicosapentaenoic and docosahexaenoic acids, but not by linolenic acid. Smooth muscle cells have little or no desaturase activity, but have significant elongation activity for polyunsaturated fatty acids.
    The Journal of Lipid Research 09/1985; 26(8):930-9. · 4.73 Impact Factor
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    ABSTRACT: Acid and neutral cholesterol esterases (CEases) in cultured rabbit smooth muscle cells (SMC) were examined. The optimal pH of acid CEase was 4.5 and its apparent Km was 83 microM. The optimal pH of neutral CEase was 7.5 and its apparent Km was 38 microM. CEases were most active with substrate vesicles prepared with phosphatidylcholine. Acid CEase hydrolyzed cholesteryl [1-14C]oleate labeled LDL (LDL-CE), but neutral CEase did not. Incubation with LDL increased the acid and neutral CEase activities of SMC, but incubation with acetylated-LDL did not increase their activities.
    The Tohoku Journal of Experimental Medicine 07/1985; 146(2):123-30. DOI:10.1620/tjem.146.123 · 1.28 Impact Factor
  • The Lancet 06/1985; 1(8437):1092-3. DOI:10.1016/S0140-6736(85)92387-6 · 45.22 Impact Factor
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    ABSTRACT: The possibility that some factor in serum changes the substrate specificity of purified human plasma carboxyl esterase, which hydrolyzes the short chain fatty acid ester, tributyrin, was investigated. The purified carboxyl esterase from human plasma hydrolyzed 48 mmol of tributyrin/mg of protein/h, monoolein at 1560 mumol of released fatty acids/mg of protein/h, diolein at 133 mumol of released fatty acids/mg of protein/h, and triolein at less than 10 mumol of released fatty acids/mg of protein/h. When human serum was applied to phenyl-Sepharose, a triolein hydrolysis-promoting factor (THPF) for purified carboxyl esterase was bound to the gel and was eluted with water. This partially purified human serum THPF enhanced carboxyl esterase-catalyzed triolein hydrolysis about 30-fold, diolein hydrolysis 2-fold, and monoolein hydrolysis 1.5-fold. Hydrolysis of triolein in very low density lipoproteins (d less than 1.006) and intermediate lipoproteins (1.006 less than d less than 1.019) by carboxyl esterase was also enhanced by addition of THPF. THPF activity was reduced by treatment of delipidation, but resistant to trypsin treatment or heating at 50 degrees C. These results indicated that serum carboxyl esterase can hydrolyze the long chain fatty acid ester, triolein, in the presence of triolein hydrolysis-promoting factor in serum.
    Journal of Biological Chemistry 06/1985; 260(9):5225-7. · 4.60 Impact Factor
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    ABSTRACT: The self-quenching dye, 6-carboxyfluorescein, has been encapsulated into sonicated vesicles of egg phosphatidylcholine. Porcine pancreatic phospholipase A2 and bovine milk lipoprotein lipase catalyze the hydrolysis of the phosphatidylcholine resulting in the release of the encapsulated dye and a large increase in 6-carboxyfluorescein fluorescence. The fluorescence increase occurs in parallel with the formation of lysophosphatidylcholine and is strongly dependent on Ca2+ for phospholipase A2 catalysis and on apolipoprotein C-II for hydrolysis by lipoprotein lipase. Other apolipoproteins, including apolipoproteins C-III, C-I, and A-I, do not enhance lipoprotein lipase activity towards this substrate. We conclude that the enhancement of lipoprotein lipase activity by apolipoprotein C-II is a specific property of the activator protein due to its interaction with lipoprotein lipase or an enzyme/lipid interface and not a characteristic of lipid-binding proteins in general.
    Biochimica et Biophysica Acta 10/1984; 795(2):191-5. DOI:10.1016/0005-2760(84)90065-1 · 4.66 Impact Factor
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    ABSTRACT: The mechanism of action of hepatic triacylglycerol lipase (EC 3.1.1.3) was examined by comparing the hydrolysis of a water-soluble substrate, tributyrin, with that of triolein by hepatic triacylglycerol lipase purified from human post-heparin plasma. The hydrolyzing activities toward tributyrin and triolein were coeluted from heparin-Sepharose at an NaCl concentration of 0.7 M. The maximal velocity of hepatic triacylglycerol lipase (Vmax) for tributyrin was 17.9 mumol/mg protein per h and the Michaelis constant (Km) value was 0.12 mM, whereas the Vmax for triolein was 76 mumol/mg per h and the Km value was 2.5 mM. The hydrolyses of tributyrin and triolein by hepatic triacylglycerol lipase were inhibited to similar extends by procainamide, NaF, Zn2+, Cu2+, Mn2+, SDS and sodium deoxycholate. Triolein hydrolysis was inhibited by the addition of tributyrin. Triolein hydrolysis was also inhibited by the addition of dipalmitoylphosphaidylcholine vesicles. In contrast, the additions of triolein emulsified with Triton X-100 and dipalmitoylphosphatidylcholine vesicles enhanced the rate of tributyrin hydrolysis by hepatic triacylglycerol lipase. In the presence of dipalmitoylphosphatidylcholine, the Vmax and Km values of hepatic triacylglycerol lipase for tributyrin were 41 mumol/mg protein per h and 0.12 mM, respectively, indicating that the enhancement of hepatic triacylglycerol lipase activity for tributyrin by dipalmitoylphosphatidycholine vesicles was mainly due to increase in the Vmax. The enhancement of hepatic triacylglycerol lipase activity for tributyrin by phospholipid was not correlated with the amount of tributyrin associated with the phospholipid vesicles. On Bio-Gel A5m column chromatography, glycerol tri[1-14C]butyrate was not coeluted with triolein emulsion, and hepatic triacylglycerol lipase activity was associated with triolein emulsion even in the presence of 2 mM tributyrin. These results suggest that hepatic triacylglycerol lipase has a catalytic site for esterase activity and a separate site for lipid interface recognition, and that on binding to a lipid interface the conformation of the enzyme changes, resulting in enhancement of the esterase activity.
    Biochimica et Biophysica Acta 09/1984; 795(1):1-8. DOI:10.1016/0005-2760(84)90097-3 · 4.66 Impact Factor
  • K Shirai, Y Saito, S Yoshida
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    ABSTRACT: Hepatic triacylglycerol lipase (EC 3.1.1.3) hydrolyzes water-insoluble fatty acid esters, e.g., trioleoylglycerol (lipase activity) and water-soluble fatty acid esters, e.g., tributyrin (esterase activity). Esterase activity of hepatic triacylglycerol lipase is enhanced by triolein emulsion and phospholipid vesicles [1]. The catalytic mechanism and structure of human hepatic triacylglycerol lipase isolated from human post-heparin plasma and the effect of trypsin treatment on the lipase and esterase activities of the enzyme were examined. Treatment of hepatic triacylglycerol lipase with trypsin resulted in loss of its lipase activity, but had no effect on its esterase activity. Chromatography of hepatic triacylglycerol lipase on Bio-Gel A5m showed that hepatic triacylglycerol lipase binds to dipalmitoylphosphatidylcholine vesicles. However, on chromatography of the trypsin-treated enzyme after incubation with dipalmitoylphosphatidylcholine vesicles, a part of hepatic triacylglycerol lipase that retained esterase activity was eluted separately from the dipalmitoylphosphatidylcholine vesicles. Addition of vesicles of dipalmitoylphosphatidylcholine to the trypsin-treated enzyme did not enhance its esterase activity. These results are consistent with the hypothesis that hepatic triacylglycerol lipase has a catalytic site that hydrolyzes tributyrin and a lipid interface recognition site, and that these sites are different: trypsin modified the lipid interface recognition site of the hepatic triacylglycerol lipase but not the catalytic site.
    Biochimica et Biophysica Acta 09/1984; 795(1):9-14. DOI:10.1016/0005-2760(84)90098-5 · 4.66 Impact Factor
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    ABSTRACT: The fluorescent phospholipid 1-acyl-2-[6-[(7-nitro-2,1,3benzoxadiazol-4 -yl) amino]-caproyl] phosphatidylcholine (C6-NBD-PC) was used as a substrate for porcine pancreatic phospholipase A2 (PA2) and bovine milk lipoprotein lipase (LpL). Hydrolysis of C6-NBD-PC by either enzyme resulted in a greater than 50-fold fluorescence enhancement with no shift in the emission maximum at 540 nm; Ca++ was required for PA2 catalysis. Identification of the products of hydrolysis showed cleavage at the sn-1 and sn-2 positions for LpL and PA2, respectively. For PA2, but not for LpL, there was a marked enhancement of enzyme catalysis at lipid concentrations above the critical micellar concentration of the lipid. Furthermore, apolipoprotein C-II, the activator protein of LpL for long-chain fatty acyl substrates, did not enhance the rate of catalysis of the water-soluble fluorescent phospholipid for either enzyme.
    Biochemical and Biophysical Research Communications 03/1984; 118(3):894-901. DOI:10.1016/0006-291X(84)91479-7 · 2.28 Impact Factor
  • Nihon Naika Gakkai Zasshi 07/1983; 72(6):796-802.
  • K Shirai, N Matsuoka, Y Saito
    Horumon to rinsho. Clinical endocrinology 06/1983; 31(5):437-41.
  • Progress in Lipid Research 02/1983; 22(1):35-78. DOI:10.1016/0163-7827(83)90003-6 · 12.96 Impact Factor
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    ABSTRACT: The lipoprotein lipase-catalyzed hydrolysis of triacylglycerol was determined in a lipid monolayer containing egg phosphatidylcholine and tri[14C]oleoylglycerol. In the presence of purified bovine milk lipoprotein lipase and fatty acid-free albumin, the rate of hydrolysis of tri[14C]oleoylglycerol, as determined by the decrease in surface activity, was dependent upon enzyme concentration and was enhanced by the addition of apolipoprotein C-II, the activator protein for the enzyme. Increasing the triacylglycerol content of the phospholipid monolayer from 1 to 6 mol% (relative to phospholipid) enhanced the rate of catalysis in the presence and absence of apolipoprotein C-II. However, at low substrate concentrations (less than 4 mol% tri[14C]oleoylglycerol), the activation factor for apolipoprotein C-II was greater than at high (4-6 mol%) triacylglycerol concentrations. The addition of sphingomyelin to the phosphatidylcholine monolayer decreased lipoprotein lipase activity. Based on these monolayer studies, we conclude that lipoprotein lipase catalyzes the hydrolysis of triacylglycerol at a phospholipid interface and that the rate of catalysis is dependent on the lipid composition of the monolayer.
    Biochimica et Biophysica Acta 01/1983; 713(3):629-37. DOI:10.1016/0005-2760(82)90323-X · 4.66 Impact Factor
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    ABSTRACT: Bovine milk lipoprotein lipase (LpL) catalyzes the hydrolysis of the water-soluble esters p-nitrophenyl acetate (PNPA) and p-nitrophenyl butyrate (PNPB). The same protein and same active site are involved in hydrolysis of water-soluble p-nitrophenyl esters and emulsified trioleoylglycerol since (a) trioleoylglycerol hydrolysis and PNPB hydrolysis activities coelute from the heparin-Sepharose affinity column used to purify LpL and (b) LpL-catalyzed hydrolyses of trioleoylglycerol and PNPB are inhibited to equal extents by phenylmethanesulfonyl fluoride. The effect of apolipoprotein C-II (apoC-II) on the LpL-catalyzed hydrolysis of PNPA and PNPB has been determined. ApoC-II inhibits hydrolysis of both esters, with a maximum extent of inhibition of 70-90%. Inhibition of the LpL-catalyzed hydrolysis of PNPB is specific for apoC-II, since apolipoproteins A-I, C-I, and C-III-2 have little effect on this reaction, and is partial noncompetitive in form. KI values for apoC-II inhibition of the LpL-catalyzed hydrolysis of PNPA and PNPB are in the range 0.26-0.83 microM. The effect of apoC-II on the temperature dependences of LpL-catalyzed hydrolysis of both esters and on NaCl inhibition of LpL-catalyzed PNPB hydrolysis is consistent with a change in rate-determining step with LpL and apoC-II interact. These results indicate not only that there is an interaction between apoC-II and LpL in aqueous solution in the absence of a lipid interface but also that this interaction conformationally modulates the active site of the enzyme.
    Biochemistry 01/1983; 21(26):6872-9. DOI:10.1021/bi00269a038 · 3.19 Impact Factor
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    ABSTRACT: The effect of apolipoproteins on the hepatic lipase-catalyzed hydrolysis of high density lipoprotein (HDL) triacylglycerols was studied in an in vitro system consisting of purified human post-heparin hepatic lipase, HDL2 and albumin. The apparent values of the Michaelis constant (Km) and maximal velocity (Vmax) for the hepatic lipase-catalyzed hydrolysis of HDL2-triacylglycerols were 0.18 mM and 86 nmol free fatty acids released/mg hepatic lipase per min, respectively. The addition of purified human plasma apolipoprotein A-I, A-II, E, C-I or C-III2 (containing 2 mol of sialic acid) to HDL2 caused inhibition of hepatic lipase activity. At a 1:1 weight ratio of added apolipoprotein to HDL2-protein, inhibition was 50% for apolipoprotein E and over 75% for the other apolipoproteins tested. Inhibition of enzyme activity occurred with both the unfractionated HDL2 and the HDL which were reisolated by ultracentrifugation. The major alteration in the composition of the reisolated HDL was an increase in the protein to phospholipid ratio. Based on these results, we speculate on the possible role of the apolipoproteins in the metabolism of HDL2 by hepatic lipase.
    Biochimica et Biophysica Acta 12/1982; 713(2):292-9. DOI:10.1016/0005-2760(82)90247-8 · 4.66 Impact Factor
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    K Shirai, R L Jackson, D M Quinn
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    ABSTRACT: Interaction of purified bovine milk lipoprotein lipase (LpL) with sonicated vesicles of dipalmitoyl phosphatidylcholine in the gel phase is associated with an increase in the rate of the LpL-catalyzed hydrolysis of p-nitrophenyl butyrate. There is a 6-fold increase in Vmax. Apolipoprotein C-II, the activator protein for LpL, inhibits the LpL-catalyzed hydrolysis of p-nitrophenyl butyrate. With 0.5 mol % tri[14C]oleoylglycerol present in the dipalmitoyl phosphatidylcholine vesicles and in the presence of 20 mM Ca2+, the rate of p-nitrophenyl butyrate hydrolysis is decreased reciprocally compared to trioleoylglycerol hydrolysis and is dependent on apolipoprotein C-II. These results suggest that apolipoprotein C-II enhances the activity of LpL by increasing the affinity of the active site of LpL for triacylglycerol.
    Journal of Biological Chemistry 10/1982; 257(17):10200-3. · 4.60 Impact Factor

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537 Citations
144.87 Total Impact Points

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Institutions

  • 1982–1991
    • Chiba University
      • • Department of Dermatology
      • • Graduate School of Medicine
      Chiba-shi, Chiba-ken, Japan
  • 1985
    • Chiba University Hospital
      Tiba, Chiba, Japan
  • 1980–1983
    • University of Cincinnati
      • Department of Pharmacology and Cell Biophysics
      Cincinnati, Ohio, United States