Coding sequence of human placenta cofilin cDNA.
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Actin Depolymerizing Factors↗
Biomedical subjects
M Okuma
Publications and source records attributed to M Okuma.
Deficient elevation of the cytoplasmic calcium ion concentration by epinephrine in epinephrine-insensitive platelets of patients with myeloproliferative disorders.
Elevation of the cytoplasmic Ca2+ concentration ([Ca2+]i) by epinephrine and epinephrine-induced inhibition of prostaglandin E1 (PGE1)-stimulated cyclic adenosine monophosphate (cAMP) accumulation were assessed in platelets from three groups of subjects; normal controls (NS, n = 11) and patients with myeloproliferative disorders whose platelets were either sensitive (ES, n = 9) or specifically insensitive (El, n = 7) to the aggregatory effect of epinephrine. The inhibition by epinephrine of cAMP accumulation in the platelets exposed to 500 nM PGE1 was not significantly different between the three groups. Therefore, despite the defective aggregation response to epinephrine, platelets from the El group seemed to retain normal response, which was attained through alpha 2-adrenergic receptors, guanine nucleotide binding regulatory protein, and the adenylate cyclase system. However, in aequorin-loaded, washed platelets, the epinephrine-stimulated rise in [Ca2+]i showed significant decrease in the El group compared with the other groups (P less than 0.01). Thus the mechanism for the impaired aggregation response to epinephrine in platelets from the El group could include the defect that exists in the pathway from receptor binding of epinephrine to the aggregation response through [Ca2+]i elevation.
Blood Platelets↗
[1H-NMR studies of plasma from patients with liver diseases].
We examined the 1H-NMR spectra of the lipid region of human plasma according to the method of Fossel et al. as the specific blood test for cancer. The study group included 20 patients with hepatocellular carcinoma (HCC), 10 patients with liver cirrhosis (LC) and 10 normal controls (NC). We measured the linewidths of methyl and methylene resonances of lipoprotein lipids at a proton resonance frequency of 400 MHz using a JNM GX400 FT NMR spectrometer. The mean linewidth values and the standard deviation of methyl were as follows: 41.3 +/- 7.2 Hz (NC), 34.8 +/- 6.9 Hz (LC), 29.6 +/- 5.7 Hz (HCC). There was thus a significant difference between NC and HCC. On the other hand, there was no significant difference between the three groups in the case of methylene. Although the spectrum in the HCC and LC groups had a blunt head but narrow body, that of the NC group had a pointed head but wide body, and the linewidth values thus showed wide dispersion. This difference in spectral patterns between the two groups was characteristic. Linewidth values, however, did not correlate well with the laboratory data.
Adult↗
Hepatic function and portal hemodynamics in patients with liver cirrhosis.
We investigated the distribution of portal blood flow per kilogram of body weight (PBF/BW) in 112 healthy volunteers and 90 patients with liver cirrhosis using an ultrasonic Doppler duplex system. The PBF/BW in healthy volunteers showed a log-normal distribution, while the distribution was irregular and showed two peaks in patients with cirrhosis. This irregular distribution was thought to reflect their complex physiopathological state. We next analyzed the relationship between PBF/BW and the data from hepatic function tests (serum albumin, total bilirubin, indocyanine green 15-min retention rate, and indocyanine green plasma disappearance rate) in 48 patients with liver cirrhosis. The patients were divided into four groups according to their portal blood flow: group A with a hepatofugal or stagnant portal blood flow, group B with a hepatopetal PBF/BW of less than 12 ml/min/kg, group C with a hepatopetal PBF/BW of 12 or more but less than 20 ml/min/kg, and group D with a hepatopetal PBF/BW of 20 ml/min/kg or more. Among patients with cirrhosis, group A showed the worst results in hepatic function tests, group D the second worst, and group C the best. The effective hepatic blood flow was thought to have decreased because of the development of extrahepatic portosystemic shunts in the patients in groups A and B, whereas it decreased because of the development of intrahepatic shunts in patients in group D. The results of hepatic function tests deteriorated as a consequence of the decrease in the effective hepatic blood flow.
Adult↗
[The changes in hepatic hemodynamics and hepatic energy charge (blood ketone body ratio) induced by vasopressin infusion in chronic liver disease].
We evaluated the changes in the hepatic hemodynamics and blood ketone body ratio (KBR) induced by vasopressin in 40 patients with chronic liver diseases to clarify the effect of hepatic blood flow on hepatic energy charge expressed by KBR. Following infusion of vasopressin, the rate of decrease in portal blood flow in liver cirrhosis (LC) was significantly lower than that in chronic hepatitis (CH). Moreover, the blood flow in the hepatic artery after vasopressin infusion was greater in LC than in CH. As a result, the total hepatic blood flow, which was the sum of the flow in the above two vessels, after vasopressin infusion was greater in LC than in CH but the decrease in the blood KBR was not significant in LC. Thus, vasopressin appears to be hemodynamically safe in patients with LC, but caution is needed since it may decrease blood pressure, total hepatic blood flow and KBR in some LC patients.
Adult↗
[A long-term observation of development from monoclonal gammopathy of undetermined significance (MGUS) into primary amyloidosis].
The term, "monoclonal gammopathy of undetermined significance (MGUS)" is used because it is not known at the time of recognition whether the M-component will remain stable or will develop into multiple myeloma (MM) or related disorders. Recently, we have encountered a case of MGUS in which a diagnosis of primary amyloidosis (PA) was made more than 10 years after the recognition of an M-component in the serum. A 64-year-old man presented in 1979 for evaluation of monoclonal gammopathy. The level of M-component (IgG-lambda) in the serum was 1.6 g/dl. The urinary Bence Jones proteins (BJP) were negative. Bone marrow aspirate contained 9.8% plasma cells. Skeletal surveys were normal. A diagnosis of MGUS was made. In 1982, a trace amount of BJP was detected in the urine. Since 1988, carpal tunnel syndrome, angina pectoris and congestive heart failure developed in succession. In November 1989, the patient was admitted to Kyoto University Hospital for examination. Serum electrophoretic pattern remained unchanged. The excreted amount of urinary BJP was less than 0.3 g/day. Bone marrow aspirate contained 5.4% plasma cells. Histologic studies of bone marrow biopsy specimens revealed amyloid deposition. An echocardiogram was thought to reveal amyloidosis. Significant uptake of Tc-99m (V) DMSA was found in carpal regions, kidneys and heart. A diagnosis of PA was made. It is noteworthy that the development of PA did not accompany an increase in the serum M-component. An early diagnosis of PA as well as MM should be kept in mind in the follow-up study of patients with MGUS.
Aged↗
[Role of arachidonic acid cascade and related substances in blood and bone marrow cells].
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Animals↗
Purification of the thromboxane A2/prostaglandin H2 receptor from human blood platelets.
S-145 (5Z-7-(3-endo-phenylsulfonylamino-(2.2.1.)-bicyclohept -2-exo-yl) heptenoic acid) is a potent and selective antagonist for thromboxane A2/prostaglandin H2 receptor. Using this compound as an immobilized ligand for affinity chromatography and [3H]S-145 as a radioligand, we have purified the thromboxane A2/prostaglandin H2 receptor from the membranes of human blood platelets. The purification procedures consisted of solubilization of the receptor with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), affinity chromatographies on columns of S-145 affinity gel, wheat germ agglutinin agarose and red agarose, and repeated gel filtration high performance liquid chromatography on a TSK gel G-3000SW column. On the second gel filtration high performance liquid chromatography, the [3H]S-145 binding activity was eluted as a symmetrical peak which overlapped exactly with a peak of ultraviolet absorption at 280 nm. By these procedures, the receptor was purified about 8700-fold from the solubilized extract with a recovery of 6%. The final preparation showed a broad protein band at Mr 57,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and maximally bound 19.2 nmol of [3H]S-145/mg protein with a Kd of 29.8 nM. The [3H]S-145 binding to the purified receptor was specifically displaced by several thromboxane A2/prostaglandin H2 analogues.
Binding, Competitive↗
Expression of thromboxane A2 receptor in cultured human erythroleukemia cells and its induction by 12-O-tetradecanoylphorbol-13-acetate.
Using [125I]I-S-145-OH, a radiolabeled derivative of a thromboxane (TX) A2 receptor antagonist, we have studied the expression of the TXA2 receptor in several lines of cultured leukemia cells. Specific binding of the ligand was observed in cells of two human erythroleukemia cell lines, K562 and HEL. However, only negligible binding was seen in HL-60 human promyelocytic leukemia cells and L-1210 murine leukemia cells. Scatchard analyses revealed a curvilinear plot which indicated the existence of two classes of binding sites in these cells. The Kd and Bmax values of the high and low affinity bindings in HEL cells were 2.4 nM and 24 fmol/10(6) cells, and 58 nM and 360 fmol/10(6) cells, respectively. These values in K562 cells were 2.8 nM and 16 fmol/10(6) cells, and 18 nM and 46 fmol/10(6) cells, respectively. The addition of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) to the cultures of K562 and HEL cells caused a concentration- and time-dependent increase in the binding activity. TPA at 10(-8) M increased the Bmax values of both high and low affinity bindings approximately 3 times without significant change in their Kd values and these increases were inhibited by the addition of actinomycin D. Both classes of the binding in cells of each cell line were specifically displaced by several TXA2/prostaglandin (PG) H2 analogues, although the relative specificities to the analogues were different in the two classes. These results suggest that both HEL and K562 cells express the TXA2 receptor on their cell surface and TPA strongly induces this expression in these cells.
Animals↗
A case of exercise-induced anaphylaxis: evidence of an association with the complement system.
We studied a 17-year-old girl with exercise-induced anaphylaxis (EIA). She experienced 10 episodes of EIA which demonstrated cutaneous, digestive and cardiorespiratory symptoms. This subject exhibited elevation in plasma histamine (13.3 ng/ml) and decrease in CH50 (17 U/ml) and C3 (70 mg/dl) after naturally induced EIA. On remission day CH50 (26 U/ml), C3 (83 mg/dl) and C4 (15 mg/dl) were of relatively low values. Her mother demonstrated the same tendency with a low level of C4 (14 mg/dl), and this suggested an underlying genetic disorder in the complement system. Exercise challenge could not elicit EIA symptomatically but showed fluctuation of CH50. The triggering mechanism of EIA was unclear; however there is a possibility that complement plays an important role in EIA.
Adolescent↗
A patient with platelets deficient in glycoprotein VI that lack both collagen-induced aggregation and adhesion.
Molecular level studies on platelets deficient in collagen-induced aggregation provide evidence for identifying possible platelet collagen receptors. We investigated platelets from a patient with mild bleeding time prolongation, but otherwise normal coagulation data. Her platelets lacked collagen-induced aggregation and adhesion, but retained normal aggregation and release by other agonists. Labeling her platelets with 125I or 3H and analysis by SDS-PAGE/autoradiography showed normal levels of glycoproteins Ia, Ib, IIa, IIb, IIIa, and IV. However, there were significantly decreased incorporations of both radioactivities into a 61-kD membrane glycoprotein (GP), which was identified as GPVI from its mobility on unreduced-reduced, two-dimensional SDS-PAGE. Sugiyama et al. (1987. Blood. 69: 1712) reported that the serum from an idiopathic thrombocytopenic purpura (ITP) patient contained an antibody against a 62-kD platelet protein. Our patient's platelets lacked the antigen for the ITP patient's antibody, demonstrating that the ITP serum contains a specific antibody against GPVI. The patient's parents' platelets contained approximately 50% the normal amount of GPVI, but still had normal collagen-induced aggregation and adhesion. The patient's platelets did not bind to types I and III collagen fibrils. Our results suggest that GPVI functions as a collagen receptor.
Adult↗
Effects of dilazep on cytoplasmic calcium ion concentrations and arachidonic acid metabolism in activated human platelets.
The effects of dilazep (tetrahydro-1H-1,4-diazepine-1,4(5H)-dipropanol bis(3,4,5-trimethoxybenzoate)-di-hydrochloride monohydrate, Comelian), a coronary and cerebral vasodilator and an antiplatelet drug, on the cytoplasmic Ca2+ concentration ([Ca2+]i) and arachidonic acid (AA) metabolism in activated human platelets were investigated. [Ca2+]i (free calcium ion concentration) of aequorin-loaded platelets was estimated by using the platelet ionized calcium aggregometer. AA metabolism was studied by the determination of AA metabolites, hydroxyheptadecatrienoic acid and 12-hydroxyeicosatetraenoic acid, using reversed-phase high performance liquid chromatography. When platelets were preincubated with dilazep (0-0.5 mmol/l), the drug inhibited both platelet aggregation and [Ca2+]i elevation induced by thrombin, AA and collagen in a concentration dependent manner, while only aggregation was inhibited after stimulation with the Ca ionophore A23187 (calcimycin). Both influx and release of Ca2+ into platelet cytoplasm induced by thrombin or AA were inhibited by dilazep, while neither of them was affected when induced by A23187. Oral ingestion of dilazep as a 100-mg capsule significantly depressed the [Ca2+]i elevation induced by thrombin, AA and collagen after 3 h. Dilazep inhibited endogenous AA metabolism by platelets induced by thrombin, although it enhanced exogenous one. Thus, dilazep inhibited platelet aggregation induced by any agonists including A23187, while [Ca2+]i elevation was inhibited by the drug only when the receptor-mediated agonist was used. Furthermore, it is suggested that dilazep inhibited AA liberation from platelet membrane phospholipids, leading to reduced production of all endogenous AA metabolites after platelet activation although metabolites of exogenous AA could be increased.
Adult↗
Effects of dilazep on arachidonic acid metabolism by neutrophils and platelet/neutrophil interactions.
The effect of dilazep (tetrahydro-1H-1,4-diazepine-1,4(5H)-dipropanolbis(3,4, 5-trimethoxy-benzoate)dihydrochloride monohydrate, Comelian), a coronary and cerebral vasodilator and an anti-platelet agent, on endogenous and exogenous arachidonic acid (AA) metabolism by human neutrophils and platelet/neutrophil interactions was studied in vitro. Neutrophils preincubated with dilazep (up to 300 mumol/l) were incubated with the Ca ionophore A23187 in the absence or presence of AA. Platelet/neutrophil mixtures preincubated with dilazep (up to 100 mumol/l) were incubated with thrombin plus N-formylmethionylleucylphenylalanine (FMLP), FMLP plus AA, and platelet-activating factor (PAF) plus AA. AA metabolites including leukotriene B4 (LTB4), 5-hydroxyeicosatetraenoic acid (5-HETE) and 5S,12S-dihydroxyeicosatetraenoic acid (5S,12S-DiHETE) were analyzed and quantitated by reversed-phase high-performance liquid chromatography. The formation of LTB4 and 5-HETE from endogenous AA by neutrophils was inhibited by dilazep, whereas their production from exogenous AA was enhanced. LTB4 synthesis from endogenous AA by platelet/neutrophil interactions was inhibited by dilazep, while 5S,12S-DiHETE production was increased. The production of 5-lipoxygenase metabolites from exogenous AA by these interactions was increased by this drug. Thus, dilazep inhibits endogenous AA metabolism by neutrophils and by platelet/neutrophil interactions, whereas it stimulates exogenous AA metabolism by these blood cells and their interactions.
Arachidonic Acid↗
Reduced 12-lipoxygenase activity in platelets of patients with myeloproliferative disorders.
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Arachidonate 12-Lipoxygenase↗
[3H]S-145 and [125I]I-S-145-OH: new radioligands for platelet thromboxane A2 receptor with low nonspecific binding and high binding affinity for various receptor preparations.
Two new radioligands for the TXA2 receptor, [3H]S-145 (5Z-7-(3-endo-[( ring-4-3H]phenyl)sulphonylamino- [2.2.1.]bicyclohept-2-exo-yl) heptenoic acid) and [125I]I-S-145-OH (5Z-7-(3-endo[( 125I] 3-iodo-4-hydroxyphenylsulphonyl)amino- [2.2.1.] bicyclohept-2- yl)heptenoic acid) were synthesized and their binding to washed human platelets, platelet membrane and solubilized TXA2 receptor was examined. Both [3H]S-145 and [125I]I-S-145-OH bound to the above preparations in a saturable and reversible manner. In contrast to the conventional TXA2 receptor ligands, such as [3H]U-46619 and [125I]PTA-OH, nonspecific binding of these radioligands constituted less than 10% of the total binding under the standard assay conditions. Scatchard analysis revealed a single class of binding sites for all three preparations; the Kd values of the [3H]S-145 binding were 3.64, 3.14 and 8.22 nM for washed platelets, platelet membrane and the solubilized receptor, respectively, and those of [125I]I-S-145-OH binding were 5.72 and 4.09 nM for washed platelets and the solubilized receptor, respectively. Thus, [3H]S-145 and [125I]I-S-145-OH are the ligands with low nonspecific binding and the highest affinities for the TXA2 receptor, which are independent of membrane preparation and receptor solubilization. In addition, the alpha-carboxyl group of S-145 could be modified without change in the binding affinity.
Azides↗
Thrombocytosis and thrombocythemia: qualitative platelet abnormalities.
Thrombocytosis occurs as a primary disease of the bone marrow (primary thrombocytosis or thrombocythemia) or as a reactive phenomenon in pathologic and physiologic conditions (secondary thrombocytosis or thrombocytosis in a narrow sense). As a rule, secondary thrombocytosis is symptomless and shows normal platelet functions, while thrombocythemia is frequently associated with bleeding and/or thrombosis as well as various platelet abnormalities. These platelet abnormalities were reviewed, and our recent studies on functional and biochemical alterations in platelets of thrombocythemia were focused on: 1) abnormal platelet aggregation. 2) deficient epinephrine-induced elevation of the cytoplasmic Ca2+ concentration in platelets with defective aggregation response to epinephrine, 3) altered (subnormal and increased) platelet responses to thromboxane A2 (abnormal thromboxane A2 receptor), and 4) abnormal platelet 12-lipoxygenase enzyme. Although the clinical significance of the in vitro qualitative platelet defects is not always clear, these altered platelets could be useful models to elucidate platelet pathophysiology.
Blood Platelets↗
Characterization of an apparently lower molecular weight gamma-chain variant in fibrinogen Kyoto I. The replacement of gamma-asparagine 308 by lysine which causes accelerated cleavage of fragment D1 by plasmin and the generation of a new plasmin cleavage site.
Congenitally abnormal fibrinogen Kyoto I with impaired fibrin monomer polymerization contains a normal gamma-chain and a gamma-chain variant (gamma Kyoto I) that has an apparently lower Mr on sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the Laemmli system (Laemmli, U. K. (1970) Nature 227, 680-685) but migrates with apparently normal Mr in the Weber and Osborn system (Weber, K., and Osborn, M. (1969) J. Biol. Chem. 244, 4406-4412). Reverse-phase high performance liquid chromatographic analyses of the cyanogen bromide or lysyl endopeptidase cleavage fragments of the purified gamma-chains of fibrinogen Kyoto I showed the presence of peptides not seen from normal fibrinogen. Amino acid sequence analysis of these peptides indicated that gamma Asn308 of the gamma-chain variant is replaced by lysine. Purified fragment D1 of fibrinogen Kyoto I also contains two types of D1 gamma-remnants: normal and apparently lower Mr types. Abnormal fragment D1 is cleaved faster to fragments D2 and D3 by plasmin in the presence of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (EGTA) than normal fragment D1, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by immunoblotting using anti-gamma-chain monoclonal antibody. Analysis of peptides released from fragment D1 by plasmin in the presence of EGTA demonstrated the cleavage of the gamma Lys308-Gly309 bond. Fragment D1 of fibrinogen Kyoto I has normal calcium binding properties. The data suggest that a region or conformation containing gamma Asn308 affects the polymerization of fibrin monomers and that the gamma Asn308----Lys replacement causes a conformational change in the gamma-chain which results in the accelerated cleavage of gamma Lys356-Ala357 and gamma Lys302-Phe303 bonds by plasmin and also results in the generation of a new plasmin cleavage site between Lys308 and Gly309 in the presence of EGTA. During these studies, we found that part of the gamma Lys212-Glu213 bond in fragment D1 is cleaved by plasmin in the presence of EGTA.
Amino Acid Sequence↗
Role of chemical mediators after antigen and exercise challenge in children with asthma.
Changes in chemical mediators after antigen challenge and exercise challenge tests were studied in children with asthma. Chemical mediators studied after antigen challenge and exercise challenge included histamine, leukotrienes (LTB4, LTC4, and LTD4), and neutrophil chemotactic factor of anaphylaxis (NCA). The pharmacologic modification of immediate and late-phase reactions was evaluated for procaterol (beta 2-agonist), cromolyn sodium, and prednisolone. Histamine levels were noted to rise in patients who had a dual response of a mild to moderate nature, but did not change in patients who had severe asthma. During exercise challenge cromolyn sodium inhibited both immediate and late-phase reactions but also inhibited plasma generation of NCA. Prednisolone, on the other hand, did not affect immediate reactions, but blocked late-phase reactions to exercise and also decreased NCA generation. Procaterol inhibited the generation of LTD4 and also inhibited NCA when compared with placebo. Exercise challenge did not alter levels of plasma histamine or of LTB4 or LTC4.
Adolescent↗