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Biomedical subjects

N Muramatsu

Publications and source records attributed to N Muramatsu.

At least 55 records · Page 3Linked to original sources
PubMed1987

A novel immobilized-enzyme system utilizing microcapsules.

A novel immobilized-enzyme system that has glucoamylase on the surface of, and glucose oxidase within, polyurea microcapsules was developed. This system was found to carry out its sequential enzymatic reaction effectively. It was also demonstrated that the use of microcapsules was useful for this immobilized-enzyme system since a large amount of the second enzyme, glucose oxidase, was required for the sequential reaction to proceed efficiently. In addition, this system was found helpful for making the size of reaction batches smaller.

Enzymes, Immobilized↗
PubMed1984

Adhesion of platelets to microcapsules and the role of complement.

Rabbit platelets rapidly adhered to carboxylated polyamide microcapsules through the adsorbed layer of plasma components. These components were found to be heat-labile proteins, which exist in fresh serum, and to demand calcium ions to function. These findings ascribed the components to the complement system. In fact, a good correlation was obtained between platelet adhesion to, and complement fixation by, the microcapsules. Moreover, the activation of the complement system by the microcapsules was assumed to proceed via the classical pathway. It was concluded that adhesion of platelets to the microcapsules is brought about by immune adherence.

Animals↗
PubMed1983

Platelet adhesion onto microcapsule membranes with different degrees of sulfonation.

Microcapsules having different numbers of sulfonic acid groups on their surfaces were prepared by the interfacial polycondensation method. Platelets adhered to these capsules, and the rate and degree of platelet adhesion were found to be remarkable on those microcapsules that had high surface charge compared to those with low surface charge. This trend was strengthened by the coating of the capsules with plasma, while the electrophoretic mobilities of the plasma-coated capsules showed a considerable reduction and no appreciable difference between the respective mobilities could be observed. This trend suggest that the adsorption of plasma components on microcapsules, and not their surface negative charge, affected platelet adhesiveness directly. In connection with the glycosyl transferase hypothesis, the adsorption pattern and its effect on platelet adhesion of albumin, gamma-globulin, and fibrinogen were examined. The protein adsorption pattern varied depending on both the type of protein and the magnitude of negative charge on the microcapsule surface, but its effect on platelet adhesion was not fully consistent with the glycosyl transferase hypothesis. It was concluded from the findings that the surface negative charge of the capsules strongly affected the composition, molecular orientation, and/or configuration of the adsorbed plasma components, which probably induced the differences in platelet adhesiveness depending on the magnitude of surface negative charge of the microcapsules.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1981

Platelet adhesion onto sulfonated artificial red blood cells.

Rabbit hemolysate-loaded microcapsules having sulfonic acid groups on their surface were prepared and rabbit platelet adhesion onto the sulfonated surface was examined kinetically. Rabbit platelets adhered more markedly onto the surface of a higher charge density than that of a lower one, indicating a trend similar to that found in the case of the surface having carboxyl groups. Moreover, the platelets were found to be stickier in the buffer solution than in the plasma, though the dependence of platelet adhesion in the buffer solution on the magnitude of surface charge of the sulfonated artificial red blood cells was still recognized.

Adenosine Diphosphate↗
PubMed1980

Platelet adhesion onto artificial red blood cells.

Several kinds of polyamide microcapsules containing mammalian hemolysate were prepared by making use of the interfacial polycondensation reaction between diamines and terephthaloyl dichloride and their blood compatibility in terms of platelet adhesion was examined aiming at their ultimate clinical use as artificial red blood cells. It was found that rabbit platelets adhere onto the hemolysate-loaded microcapsules in the presence of the plasma, while no platelet adhesion takes place in the absence of the plasma. This was interpreted as indicating an important role of plasma components in platelet adhesion. Moreover, platelet adhesion was observed to be facilitated by negative charges on the surface of the hemolysate-loaded microcapsules; the more negatively the surface was charge, the more easily the platelets adhered onto the surface. Finally, the present method of assessing platelet adhesion suggested the possibility of its use for kinetic study of platelet adhesion since it allowedus to make numerical evaluation of platelet adhesion as a function of time.

Animals↗
PubMed1976

Some catalytic and molecular properties of threonine deaminase from Bacillus stearothermophilus.

Threonine deaminase [EC 4.2.1.16] was highly purified from Bacillus stearothermophilus. The enzyme exhibited maximum activity at 65 degrees and at pH 9.2--9.6. It was inactivated on dilution and on storage at 4 degrees, but was protected by egg albumin. The enzyme was labile at 65 degrees, but became stable in the presence of egg albumin and isoleucine at pH 7.0. The substrate saturation curve for the enzyme reaction at 40 or 65 degrees was hyperbolic, but in the presence of isoleucine, the curve became sigmoidal (n = 2). The enzyme was more sensitive to isoleucine at 40 degrees than at 65 degrees, while valine slightly inhibited the enzyme at both 40 and 65 degrees. Inhibition of the enzyme by isoleucine was antagonized by valine at 40 and 65 degrees. These properties were essentially similar to those of the enzymes from mesophilic and thermophilic bacteria. The enzyme existed in two forms with different molecular sizes, 1.5-5 X 10(6) and 2 X 10(5) daltons, at pH 7.0 and at temperatures below 40 degrees. The larger component disaggregated into the small one at pH 8.5 or above, at temperatures above 50 degrees or in the presence of isoleucine and valine.

Geobacillus stearothermophilus↗
PubMedDate not supplied

Rathke cleft cyst: MR and biomedical analysis of cyst content.

PURPOSE: At least one type of Rathke cleft cyst has unique MR findings, specifically, high intensity on T1-weighted images and iso- to low intensity on T2-weighted images relative to white matter. To clarify the influence of cyst content on MR images, we analyzed the cyst content by biomedical methods after surgical removal. METHOD: We studied five patients diagnosed with Rathke cleft cyst, whose MR images showed high intensity on T1-weighted images and iso- to low intensity on T2-weighted images. After surgery, total protein and cholesterol levels were quantified, and correlations of protein and cholesterol content with T1 and T2 signal intensities were performed in vitro. RESULTS: All five cysts had very high concentrations of protein (11,700-26,600 mg/dl, mean 17,940 mg/dl) with nearly no cholesterol (at most 2.0 mg/dl). Along with increases in protein concentration in vitro, the signal intensity of T1-weighted images increased, while that of T2-weighted images decreased. In contrast, the cholesterol concentration sequence influenced the signal intensity of neither T1- nor T2-weighted images. CONCLUSION: The unique MR finding of Rathke cleft cysts--high signal intensity on T1-weighted images and low signal intensity on T2-weighted images--might depend mainly on protein concentration, not on cholesterol.

Adult↗
PubMedDate not supplied

Phagocytosis of microcapsules by guinea-pig polymorphonuclear leucocytes.

Phagocytosis of microcapsules by guinea-pig polymorphonuclear leucocytes (PMNs) was examined particularly considering the method of measurement and the effects of surface negative charges of the microcapsules and plasma proteins. Estimation of phagocytosis by oxygen consumption was found to correlate fairly well with the measured amount of the microcapsules phagocytosed. In the absence of plasma proteins, microcapsules having the same surface negative charge as that of the PMNs underwent less phagocytosis than those having surface negative charges different from those of the PMNs. The presence of plasma proteins was found to suppress phagocytosis.

Animals↗
PubMedDate not supplied

A study on heat-resistance of microencapsulated glucose oxidase.

Polyurea microcapsules containing glucose oxidase were prepared and their thermodurability was examined. Microencapsulated glucose oxidase was found to be more stable to heat than the enzyme in free solution. This stability was enhanced with an increase in the amount of enzyme entrapped in the microcapsules.

Drug Compounding↗