Biomedical subjects

A Takada

Publications and source records attributed to A Takada.

At least 379 records · Page 21Linked to original sources

PubMed1987

Kinetic analyses of the activation of Glu-plasminogen by urokinase in the presence of fibrin, fibrinogen or its degradation products.

The kinetics of the activation of Glu-plasminogen (Glu-plg) and Lys-plasminogen (Lys-plg) by urokinase (UK) were studied in purified systems. The activation of plasminogen by UK in the purified systems followed Michaelis-Menten kinetics with a Michaelis constant (Km) of 1.45 microM and a catalytic rate constant (kcat) of 0.93/sec for Glu-plg as compared to 0.25 microM (Km) and 0.82/sec (kcat) for Lys-plg. In the presence of fibrin and fibrinogen or its plasmin degradation products (fragment D and fragment E), Km for Glu-plg hardly changed, whereas kcat for Glu-plg increased. Effect on increase in kcat was in the order of fibrin greater than fibrinogen greater than D greater than E. Fibrin, fibrinogen, D and E did not influence the activation of Lys-plg by UK. These results indicate that Glu-plg bound to fibrin, fibrinogen, D or E becomes easily activatable by UK. The activation of Lys-plg, however, is not influenced in the presence of fibrin, fibrinogen, D or E.

Enzyme Activation↗

PubMed1987

Differences in the activation rates of plasminogen by tissue plasminogen activator and urokinase.

The activation of a native form of plasminogen (Glu-plg) by tissue plasminogen activator(t-PA) was enhanced when the plasma was clotted by the addition of thrombin or thrombin plus Ca++. Cross-linking of fibrin in the clotted plasma did not inhibit the fibrin-associated enhancement of the activation of plasminogen by t-PA. When fibrinolysis induced by t-PA in the clotted plasma was measured using enzyme immunoassay, lysis of non cross-linked fibrin in the clotted plasma was faster than lysis of cross-linked fibrin, however such decrease in the extent of fibrinolysis was observed in cross-linked fibrin even in the absence of alpha 2antiplasmin (alpha 2AP) in a purified system. When Glu- or Lys-plg (modified plg) was activated by t-PA, the presence of fibrin enhanced significantly the extent of activation of both Glu- and Lys-plg, but the activation of Glu-plg by urokinase (UK) was enhanced in the presence of fibrin. The activation of Lys-plg by UK was rather inhibited in the presence of fibrin.

Enzyme Activation↗

PubMed1987

Relationship between urinary fibrinogen degradation products and various types of chronic nephritis.

The concentration of urinary fibrin(ogen) degradation products (FDP) was determined by using enzyme immunoassay and radio immunoassay, and their urinary levels were compared with histologically classified types of glomerulonephritis. Urinary FDP levels were higher in the severe type of proliferative glomerulonephritis and at the active phase of systemic lupus erythematosus (SLE). They were also high in the membranous glomerulonephritis. Molecular weight of urinary FDP of a patient with severe proliferative glomerulonephritis was determined to be 150,000 and 68,000, respectively after gel filtration. Urinary FDP levels were higher in patients with glomerular fibrin deposit than in patients without fibrin deposit or normal volunteers. The amounts of excreted protein in urine was not related to the amounts of FDP. Decrease in the reciprocal of serum creatinine levels resulted in high urinary FDP levels, indicating that high urinary FDP levels may represent deterioration of renal function.

Chromatography, Gel↗

PubMed1987

Incorporation of palmitic acid in the organ of Corti as revealed by autoradiography.

The sites of incorporation of [3H]palmitic acid perfused through the scala tympani of the guinea pig cochlea were localized autoradiographically. The most active incorporation occurred in the lipid globules of Hensen's cells, followed by the hair cells, myelin of the cochlear nerve and other cells. It is speculated that the lipid globules of Hensen's cells act as a reservoir of the vitamin A esterified by fatty acids.

Animals↗

PubMed1987

Effects of malotilate on ethanol-inhibited hepatocyte regeneration in rats.

The effects of malotilate, a hepatotrophic drug, on the inhibition of hepatocyte regeneration induced by ethanol were studied in rats. Following acute ethanol administration, both DNA synthesis and commencement of the S phase of the cell cycle in hepatocytes after partial hepatectomy were delayed. Malotilate prevents this ethanol-induced delay. Upon chronic ethanol administration, DNA synthesis after partial hepatectomy was reduced and commencement of the S phase was retarded. Treatment with malotilate clearly lessened the reduction in DNA synthesis in the resected liver, and retardation of the cell cycle was partially inhibited. These results indicate that malotilate prevents the ethanol-induced inhibition of hepatocyte regeneration at the dose tested and that this drug may be effective for the treatment of alcoholic liver disease.

Animals↗

PubMed1987

Kinetic analyses of potentiation of plasminogen activation by streptokinase in the presence of fibrin or its degradation products.

When Glu-plasminogen (Glu-plg) was activated by various amounts of streptokinase (SK), Km of the hydrolysis of S-2251 by the mixture of Glu-plg and SK did not change, but Vmax increased with an increase in the amount of SK. Since low concentrations of SK-plg complex do not result in its conversion to the SK-plasmin complex by mutual activation, these results seem to suggest that the SK-plg complex may be a better activator when S-2251 is used as a substrate. When Glu-plg was activated by SK in the presence of fibrin(ogen) or its degradation products (potentiating agents), Km did not change with an increase in the concentration of each potentiating agent, but Vmax increased. The effects of potentiating agents on the kcat values of these activators were in the order of fibrin greater than fibrinogen greater than D greater than E.

Drug Synergism↗

PubMed1987

Effects of lysine and glutamic acid or [corrected] Mg++ on the conformations of C3 and B, and the activation of the alternative complement pathway.

The conversion of C3 and B in the mixture of C3, B, D and Mg++ ions was inhibited in the presence of arginine and lysine, but not in the presence of glutamic acid and aspartic acid among other amino acids. Application of dialyzed plasma to a lysine-Sepharose column resulted in elution of B and a part of D in pass-through fractions, and C3 and the other part of D were retained in the column, subsequently eluted by increase in salt concentrations. C3, B and a part of D were eluted in pass-through fractions, and C3 and the other part of D were retained in the column, subsequently eluted by increase in salt concentrations. C3, B and a part of D were eluted in pass-through fractions when applied to glutamic acid-Sepharose. A highly purified D preparation appeared in the pass-through fraction of the lysine-Sepharose column, suggesting that D may form a complex in plasma. The intensity of intrinsic fluorescence of C3 decreased in the presence of arginine to the largest extent. Lysine affected the intensity less than arginine. Kd was calculated to be 0.42 mM for arginine and 0.55 mM for lysine in the interaction with C3. The intensity of intrinsic fluorescence of B decreased in the presence of aspartic acid and glutamic acid (Kd = 0.48 mM for aspartic acid and 0.24 mM for glutamic acid). Arginine or lysine affected the intensity of B less than those anionic amino acids. The presence of Mg++ ions resulted in a decrease in the fluorescence intensity of C3 and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗

PubMed1987