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Biomedical subjects

S Takasugi

Publications and source records attributed to S Takasugi.

At least 55 records · Page 3Linked to original sources
PubMed1981

Kinetic studies of three different molecular forms of urokinase for the activation of native human plasminogen.

The kinetic parameters of three different molecular forms of urokinase (UK) for the activation of native Glu-plasminogen were compared. The apparent Michaelis constant (Km. app.) of each UK was almost of the same order of magnitude (31-38 microM), but the catalytic constants (kc) were observed to be different: UKh (high molecular weight form, molecular weight 53,000), 2.4 +/- 0.2 s-1; UK+ (low molecular weight form, molecular weight 33,000), 0.83 +/- o.10 s-1, and UKl (trypsin-digested form, molecular weight 36,000), 0.91 +/- 0.18 s-1. The overall second order rate constant, kc/Km calculated for UKh was 7.7 X 10(4) M-1 s-1, higher than for UKl (2.2 X 10(4) M-1 s-1) or UKt (2.4 X 10(4) M-1 s-1), indicating the possibility of a much higher degree of enzymatic specificity and efficiency.

Endopeptidases↗
PubMed1981

Effect of cepharanthine on neuro-humoral excitatory responses of gastric movement in dog.

In order to clarify the role of histamine in the neuro-humoral excitatory mechanism in the stomach, the effect of cepharanthine (an inhibitory agent of histamine release from mast cells) on excitatory response of gastric movement and increase in gastric mucosal histamine content caused by nerve stimulation (vagus and splanchnic nerves) or administration of tetragastrin were investigated in dogs. The animals were anesthetized with pentobarbital sodium and immobilized with gallamine triethiodide. The following results wee obtained. Increase of gastric mucosal histamine content caused by vagal and splanchnic nerve stimulation and administration of tetragastrin was inhibited by administration of cepharanthine. Cepharanthine inhibited the tonic contraction of the innervated antral pouch or isolated antral circular muscle strip caused by stimulation of vagus nerve. Tonic contraction of the innervated antral pouch caused by electrical stimulation of the splanchnic nerve after nicotinization of celiac and superior mesenteric ganglia was inhibited by administration of cepharanthine. Cepharanthine inhibited motor excitatory response of the denervated corpus pouch caused by stimulation of vagus and splanchnic nerves and by administration of tetragastrin. These results support the theory that cepharanthine inhibits the release of histamine from histamine-secreting cells in the gastric mucosa. It is suggested that histamine plays an important role in the neuro-humoral excitatory mechanism of gastric movement.

Alkaloids↗
PubMed1980

Studies on a kallikrein-kinin system in plasma of patients with acute pancreatitis: the preparation and characterization of a kallikrein-like enzyme in patient's plasma.

In a previous paper, the authors reported that the kallikrein-like activity was eluted in alpha 2-macroglobulin fractions when patient's plasma was fractionated with Sephadex G-200 gel filtration. In order to clarify the characteristics of the kallikrein-like enzyme, enzyme isolation methods were investigated. Success was attained by the addition of 1 % sodium-dodecyl-sulfate to alpha 2-macroglobulin fractions followed by G-200 chromatography. It was also confirmed that alpha 2-macroglobulin from which the enzyme was removed regained antiplasmin activity, and that some proteases other than the kallikrein-like enzyme were also bound to alpha 2-macroglobulin. The kallikrein-like enzyme isolated by sodium-dodecyl-sulfate-treatment was examined in respect of its molecular weight and its ability to be adsorbed on DEAE-cellulose and was found to possess a molecular weight approximating that of ovalbumin or human pancreatic kallikrein and a binding affinity for DEAE-cellulose. From these results, the authors speculate that during attacks of acute pancreatitis, the pancreas liberates kallikrein into the blood.

Acute Disease↗
PubMed1979

[Influence of cimetidine on neuro-humoral excitatory responses of gastric secretion and motility in dogs (author's transl].

The influence of intravenous administration of cimetidine on excitatory response of gastric secretion and motility of innervated or denervated pouches caused by electrical stimulation of vagal and splanchnic nerves and administration of tetragastrin or histamine respectively were investigated. Dogs were anesthetized with nembutal, and also immobilized with gallamine tricthiodide. The following results were obtained. (1) Administration of cimetidine inhibited the augmentation of gastric juice and acid output from the innervated corpus pouch by vagal and splanchnic nerve stimulation and vestibulo-gastric excitatory reflexes of gastric secretory functions via the vagal or splanchnic nerve. (2) Augmentation of gastric acid output from the denervated corpus pouch caused by electrical stimulation of vagal and splanchnic nerves was inhibited by administration of cimetidine. (3) Administration of cimetidine inhibited the augmentation of acid output from denervated corpus pouch caused by injection of tetragastrin or histamine. (4) The excitatory responses of gastric motility caused by nerve stimulation and administration of tetragastrin or histamine could not be effected by cimetidine. (5) No changes were observed in the gastric venous blood flow by continuous intravenous injection of cimetidine, but by rapid injection both the flow was augmented and the systemic blood pressure decreased transiently. These results indicate that histamine stimulates gastric secretory cells directly.

Animals↗
PubMed1978

Studies on the effect of plasminogen activator on the interaction between alpha 2-macroglobulin and plasmin.

Six different plasmins were prepared by incubating human plasminogen with various amounts of streptokinase or urokinase. It was confirmed that the six different plasmins possessed similar caseinolytic activities, and the inhibitory effects of a alpha 1-antitrypsin on caseinolytic activities of the six different plasmins were all the same. On the other hand, interactions between the six different plasmins and alpha 2-macroglobulin were complicated. Plasmins activated by cleavage of plasminogen were almost immediately or effectively inhibited by alpha 2-macroglobulin. However, plasmin activated by complex formation of plasminogen with streptokinase was not so immediately or effectively inhibited by alpha 2-macroglobulin. It was supposed that the difference between these two results on the interaction between plasmin and alpha 2-macroglobulin might be due to the difference in molecular form of plasmin. In the present study, it was also confirmed that streptokinase or urokinase, in free form in the reaction mixture, interfered with the interaction between plasmin and alpha 2-macroglobulin. The cause for such interference was discussed.

Fibrinolysin↗
PubMed1978

Studies on kallikrein-kinin system in plasma of patients with acute pancreatitis.

The fact that esterolytic activity is significantly elevated in plasma of patients with acute pancreatitis and that it correlates with the serum amylase level was confirmed. No kinin activity, however, was detected in plasma. To characterize the esterolytic activity, patient and normal plasmas were chromatographed on Sephadex G-200 and the esterolytic and the kinin-forming activities of each fraction were examined. In the present study, it was speculated that during attacks of acute pancreatitis, kallikrein with amylase might be liberated into blood from the pancreas. It was confirmed that almost all of the kallikrein liberated was combined with alpha1-macroglobulin, and alpha2-macroglobulin-bound kallikrein itself possessed kinin-forming activity.

Acute Disease↗