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Biomedical subjects

H Asai

Publications and source records attributed to H Asai.

At least 19 recordsLinked to original sources
PubMed1979

Studies on hemorrhagic tendency in cirrhosis of the liver.

Recently it has been paid attention whether the liver diseases might induce the disseminated intravascular coagulation (DIC) or not, although it has well known that liver cirrhosis contribute to the hemorrhagic diathesis. In this paper, we studied on the hemorrhagic tendency and hemostatic tests in the patients with liver cirrhosis in order to clarify the coagulation and fibrinolytic activity. We can conclude that the hemorrhagic diathesis occurs due to the complex of decreases in platelet number, platelet functions, clotting factors, and increased fibrinolytic activity. The increased fibrinolytic activity may be primary and the frequency of clinically important DIC is quite low.

Adult↗
PubMed1978

Some characteristics of beta-naphthyl triphosphate as a substrate of heavy meromyosin. F-actin-inactivated hydrolysis showing initial burst.

The initial burst of Pi liberation was found in the hydrolysis of beta-naphthyl triphosphate (beta-NapP3) by heavy meromyosin (HMM) in the presence of Mg ions as well as in the hydrolysis of ATP. However, unlike that of ATP, the steady-state hydrolysis of beta-NapP3 by HMM was inhibited by the addition of F-actin to the reaction solution. Although the possession of an initial burst-like property during interaction of a substrate and myosin is believed by many investigators to be a key factor in F-actin activation of substrate hydrolysis in vitro and in the molecular mechanism of muscle contraction, the above results suggest that this is not generally true. beta-NaP3 did not induce superprecipitation of actomyosin solution and suppressed ATP-induced superprecipitation.

Actins↗
PubMed1978

Improved preparation and cooperative calcium contraction of glycerinated Vorticella.

An improved method for the preparation of glycerinated Vorticella convallaria was investigated. The pretreatment of living vorticellas with a medium containing 0.1% saponins and subsequent treatment with an extraction medium containing 35% glycerol at about 0 degrees C was satisfactory. The equilibrium average length of contractile stalks of glycerinated vorticellas was measured at various free calcium concentrations in the reaction medium. It was found that the contractile element in the spasmoneme of the stalk is contracted by a cooperative interaction involving at least two calcium ions.

Allosteric Regulation↗
PubMed1978

Local migration of myosin in F-actin plus ATP solution on the boundary of a diffusion cell.

The diffusion phenomena of myosin (myosin A, H-meromyosin or subfragment-1) in F-actin plus ATP solutions were investigated. The upper part of the diffusion cell was filled with F-actin plus ATP, and the lower part was filled with F-actin, ATP, and myosin, then both parts were brought into contact so that a boundary of the two solutions was formed and the diffusion of myosin in F-actin plus ATP solutions started. The diffusion pattern was observed with a schlieren lens system. When almost all the ATP in the lower part of the cell had been consumed by actomyosin, a hyper-sharp schlieren pattern appeared near the boundary. On analyzing this pattern, it was found that a local fast migration of proteins was occurring. Simple Brownian motion of myosin molecules could not explain the hyper-sharp phenomenon. This phenomenon occurred in ther pesence of Mg2+ or Ca2+, but very little in the presence of EDTA. Although it is well known that the superprecipitation of myosin B suspension occurs only at physiological ionic strength, this phenomenon occurred over a relatively wide range of ionic strengths. The molecular mechanism of this phenomenon is discussed in relation to the basic mechanism of the interaction between myosin and F-actin.

Adenosine Triphosphate↗
PubMed1976

[Evaluation of loosening of different total hip models and neck lengths (author's transl)].

The percentage of aseptic loosening of different types of total hip prostheses in 771 cases has been evaluated. The time of follow-up ranged between 1/2 and 6 years. In prostheses of the Charnley-Müller type of loosening was 7.8% in the Charnley-Müller-Weller type with a 2-year shorter follow-up it was 2.4%. No loosening was found during the last 2 1/2 years when the prosthesis of Beck was used, which has an increased femoral shaft-neck angle and a longer stem. When a longer neck was used, the loosening averaged 5.6%. In cases of normal neck-length it was 3.6%. From the biomechanical standpoint it seems preferable to use prostheses with an increased shaft-neck angle. Comparing the rates of loosening as reported in the literature it appears that prostheses where the femur is displaced medially (by a small femoral head or increased shaft-neck angle) show a very low rate of loosening. Models with metal sockets (McKee-Farrar and Weber-Huggler) seem to have a higher rate of loosening than models with polyethylene sockets.

Biomechanical Phenomena↗
PubMed1976

Cooperative conformational change in F-actin filament induced by the binding of heavy meromyosin.

The binding of HMM to F-actin containing bound 1, N6-ethenoadenosine diphosphate (epsilon-ADP), a fluorescent analogue of ADP, caused a significant increase in the fluorescence intensity of epsilon-ADP at 410 nm on excitation at 340 nm. This increase is regarded as due to a conformational change in the actin molecule induced by HMM binding. The fluorescence intensity increase was not directly proportional to the amount of bound HMM. This phenomenon suggests that a conformational change in neighbouring actin molecules is induced cooperatively by the conformational change of the actin molecule binding HMM.

Actins↗
PubMed1976

[General pharmacological actions of l-(m-chlorophenyl)-3-N,N-dimethylcarbamoyl-5-methoxypyrazole (PZ-177)].

PZ-177 was found to have potent analgesic, anti-inflammatory and mild central depressive actions. In the present work, the general pharmacological actions of PZ-177 were tested in order to investigate other significant actions and to determine the side effects. PZ-177 showed no significant pharmacological activities on the respiratory and cardiovascular system, on the renal function, on the autonomic nervous system, on the sugar level and coagulation in blood and on local irritation. Volume and acidity of gastric juice were decreased and turn over was not inhibited in the connective tissure. Thus PZ-177 was considered to have no ulcerogenic action on the gastric mucosa. The compound relaxed the tonus of isolated small intestine, tracheal muscles and uterus and stopped spontaneous movement. Moreover the contraction of those smooth muscles by such spasmogens as acetylcholine, histamine serotonin, BaCl2 and oxytocin was inhibited by PZ-177 and the activity was almost the same with each spasmogen. It was found therefore to have spasmolytic activity and no specific antagonistic action on the chemical mediators. PZ-177 showed also wear relaxant activity on the skeletal muscle. Those actions on the muscles may have a curative effect on inflammation in bronchotracheal and gastrointestinal tracts or on pain with contraction of skeletal muscle. From the above results, it may be considered that PZ-177 is a relatively safe and useful analgesic and anti-inflammatory compound.

Anesthetics, Local↗
PubMed1975

Fluroescence properties of chlorophyll a and b monomolecular films at the air-water interface.

The fluorescence properties of chlorophyll a and b monomolecular films at the air-water interface were measured by a high sensitivity fluorophotometer using the photon-counting method. The fluorescence intensity of chlorophyll molecules in monomolecular films in the absence of any diluents did not decrease simply with the mean distance of chlorphyll molecules. Over the range of the mean distances from 27 to 21 A, three fluorescence components (peaks at 685, 695 and 715 nm) of chlorophyll a were observed. In the case of chlorophyll beta, two fluorescence components (peaks at 667 and 685 nm) were observed over the range of the mean distances from 34 to 24 A. When the mean distance was 18 A, the short wavelength component of chlorophyll beta disappeared, and only the long avelength component was observed.

Binding Sites↗
PubMed1975

Synthesis of fluorescent organic phosphates and their equilibrium binding to bovine oxyhemoglobin.

Fluorescent organic phosphates, beta-naphthyl diphosphate, beta-naphthyl triphosphate, and beta-naphthyl tetraphosphate, were synthesized from beta-naphthyl monophosphate using Pi and N,N'-dicyclohexylcarbodiimide. These organic phosphates were interacted with bovine oxyhemoglobin, all in no buffer, 0.1 M NaCl, at 25 degrees and in the pH range 5.5-7.0. Equilibrium binding parameters were determined by measuring the fluorescence quenching upon their interaction. It is indicated that bovine oxyhemoglobin has more than one binding site, one of which is very strong. The strength of binding to the stronger site is in the order beta-naphthyl tetraphosphate greater than beta-naphthyl triphosphate greater than beta-naphthyl diphosphate. The logarithms of association constants of these phosphates depend linearly on the net charges of these phosphates at any pH. The results were accounted for by electrostatic effects using a simple charge model. In that model, the average positive net charges in oxyhemoglobin involved in the binding of beta-naphthyl phosphate are shown as a function of pH. It is shown that the binding of these fluorescent organic phosphates is prevented reversibly by the excess addition of nonfluorescent organic and iorganic phosphates, inositol hexaphosphate, tripolyphosphate, and pyrophosphate. Assuming competitive binding in a single strong site, the association constants of these nonfluorescent phosphates were also determined by measuring the recovery of the fluorescence intensity upon the release of fluorescent phosphates. At pH 6.18, the association constant of pyrophosphate is lower than that of tripolyphosphate by one order.

Animals↗