PubMed Health⌕ Search

Biomedical subjects

M Nawata

Publications and source records attributed to M Nawata.

28 records · Page 2Linked to original sources
PubMed1992

Specific assay for endotoxin using immobilized histidine, Limulus amoebocyte lysate and a chromogenic substrate.

The Limulus amoebocyte lysate (LAL) test is inhibited or enhanced by many substances. In order to overcome this problem, a specific endotoxin assay method using a membrane filter unit, a chromogenic LAL reagent, and immobilized histidine (which is a specific adsorbent for endotoxins) was developed. Endotoxins are quantitatively adsorbed on immobilized histidine. The adsorbed endotoxins are separated from LAL-inhibiting or -enhancing substances by the membrane filter unit, and their activities are directly assayed with the LAL reagent in a filter cup without any inhibition or enhancement. The reproducibility and the accuracy of this method are high. This new endotoxin assay method using immobilized histidine can be used for the determination of endotoxins in a solution containing LAL-inhibiting or -enhancing substances such as amino acids and antibiotics, as an alternative to the more common gel-clot technique.

Adsorption↗
PubMed1992

High performance liquid chromatographic determination of bound sulfide and sulfite and thiosulfate at their low levels in human serum by pre-column fluorescence derivatization with monobromobimane.

A sensitive and specific high performance liquid chromatographic method for the determination of sulfide, sulfite, and thiosulfate was established. Inorganic sulfur anions were converted into fluorescent derivatives with monobromobimane. The derivatives were separated on a coupled column chromatography with a reversed-phase octadecyl silica column connected with a weakly basic anion exchanger column by isocratic elution with acetic acid solution (pH 3)-acetonitrile (13:3, v/v) containing 25 mM NaClO4. The method was applied to the determination of bound sulfide and sulfite and thiosulfate in normal human serum. Thiosulfate could be determined directly by use of an ultrafiltered sample. For the determination of bound sulfide and sulfite, the pretreatment step with continuous flow gas dialysis was effective for the sample after releasing sulfide and sulfite by reduction with dithiothreitol. The limits of quantification by the present method were 0.05 microM for thiosulfate, 0.5 microM for bound sulfide, and 0.2 microM for bound sulfite.

Bridged Bicyclo Compounds↗
PubMed1991

Specific assay for endotoxin using immobilized histidine and Limulus amebocyte lysate.

The LAL test is inhibited or enhanced by many substances. To overcome these problems, we have developed a specific endotoxin assay method using an ultrafiltration unit, a fluorometric LAL reagent, and immobilized histidine (which is a specific adsorbent for endotoxins). This method is composed of two steps. The first step is the adsorption of endotoxins. Using immobilized histidine, endotoxins are quantitatively adsorbed on the adsorbent, and the adsorbed endotoxins are separated from LAL-inhibiting or -enhancing substances by the ultrafiltration unit. The second step is the reaction of adsorbed endotoxins with the LAL reagent. The endotoxins adsorbed on immobilized histidine are directly reacted with the LAL reagent in a filter cup and show enough activity for assay. The reproducibility and the accuracy of this method are high, and the recovery of endotoxins from a sample solution is more than 95%. The new endotoxin assay method using immobilized histidine can be utilized for the determination of endotoxins in a solution containing LAL-inhibiting or -enhancing substances such as amino acids and antibiotics instead of requiring employment of the more common gel-clot technique.

Adsorption↗
PubMed1991

Improved method for measurement of rhodanese activity using methanethiosulfonate as sulfur donor substrate and its application to human serum.

We have developed a sensitive method for the measurement of rhodanese activity in human serum which is based on the colorimetric method for the determination of thiocyanate produced from methanethiosulfonate and cyanide as substrates. Thiocyanate gives a red complex with ferric ion in an acidic condition. The present method is about 70-fold more sensitive than the conventional method using cyanide and thiosulfate as substrates and correlates well (r = 0.997) with the conventional method in bovine liver rhodanese. Within-run precision of the method is 0.91% for 420 units/l serum and the calibration curve is linear up to 1850 units/l. The normal value for human serum, determined by the present method on 31 healthy persons, was 20.9 +/- 20.0 units/l (mean +/- 2S.D.). Rhodanese activity was clearly elevated in some serum samples which were observed at abnormal values in some biochemical diagnostic tests and showed significant positive correlations with guanase activity (r = 0.728, p less than 0.01) and glutamic-oxalacetic transaminase activity (r = 0.625, p less than 0.01).

Humans↗
PubMed1990

Enzymatic assay of 3-mercaptopyruvate sulfurtransferase activity in human red blood cells using pyruvate oxidase.

A highly sensitive method has been developed for the determination of 3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2) activity in human red blood cells which is based on the colorimetric method for the determination of pyruvate using the coupled color enzymatic reaction with pyruvate oxidase (EC 1.2.3.3) and peroxidase (EC 1.11.1.7). The absorbance increase of the coupled color of N-ethyl-N-(2-hydroxy-3-sulfopropyl)-m-toluidine and 4-aminoantipyrine at 555 nm is proportional to sulfurtransferase activity. The present method is more than 10-fold more sensitive and more reproducible than the usual methods, and does not require centrifugation, filtration, and neutralization steps. The calibration curve is linear up to 450 units/liter and the precision per run is 1.06% for 77.5 units/10(10) red blood cells (n = 10). Comparison with the lactate dehydrogenase method gave good correlation (r = 0.995). The normal value for the human red blood cell enzyme, determined with the present method on 30 healthy persons, was 63.8 +/- 14.4 units/10(10) cells (mean +/- 2SD).

Colorimetry↗
PubMed1988

Determination of oxidizable inorganic anions by high-performance liquid chromatography with fluorescence detection and application to the determination of salivary nitrite and thiocyanate and serum thiocyanate.

A sensitive method for the simultaneous determination of oxidizable inorganic anions (sulphide, thiocyanate, thiosulphate and nitrite) was developed by use of high-performance liquid chromatography and fluorimetric detection based on the formation of fluorescent cerium(III) by a redox reaction with cerium(IV). The detection limits are 0.1 nmol for both thiocyanate and nitrite, 0.3 nmol for thiosulphate and 0.8 nmol for sulphide per 10-microliters injection volume. This system can be utilized for the determination of salivary thiocyanate and nitrite and serum thiocyanate.

Anions↗
PubMedDate not supplied

Hemophagocytosis in autoimmune disease.

Reactive hemophagocytic syndrome (HPS) is known to be associated with various autoimmune diseases, as well as infection and/or malignancy. Here we review the features of autoimmune-associated HPS and describe the possible role of autoantibodies, especially antiphospholipid antibodies (aPL), in HPS based on data obtained from our own patients.

Antibodies, Antiphospholipid↗
PubMedDate not supplied

Cytomegalovirus infection in patients with systemic lupus erythematosus.

Cytomegalovirus (CMV) infection is known to induce several autoimmune abnormalities in mice that resemble those found in systemic lupus erythematosus (SLE). In addition, a potential role for CMV in the development and/or progression of SLE has been suggested. In order to further clarify this issue, we reviewed the relationship between SLE and CMV infection on the basis of the clinical and immunological features of cases reported in the literature and our own patients.

Adolescent↗