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Biomedical subjects

K Fukui

Publications and source records attributed to K Fukui.

At least 487 records · Page 27Linked to original sources
PubMed1974

The charge spectrum of heavy cosmic ray nuclei measured in the Biostack experiment aboard Apollo 16 using plastic detectors.

In the Biostack experiment flown aboard Apollo 16 plastic detectors were used to select those individual biological objects which were hit by single heavy cosmic-ray nuclei during the 266 hours of space flight. The energy loss deposited in the biological object can be determined. This method needs a separate calibration in every experiment, i.e. an individual track etching rate as function of the energy loss. This calibration is given. An area of 36 cm2 of eight cellulose nitrate sheets was scanned for tracks of heavy cosmic-ray particles that stopped in the sheets. About 200 particles could be evaluated. Calibration was achieved using the oxygen isotope 16O of the cosmic-ray ions and the charge spectrum of all measured particles (Z=5-16) could be obtained.

Calibration↗
PubMed1974

Some Immunochemical Properties of Dextransucrase and Invertase from Streptococcus mutans.

Dextransucrase and invertase of some strains of Streptococcus mutans were examined by immunodiffusion with antisera against enzymes purified from strain HS-6 (Bratthall's serotype a). Both antisera cross-reacted with crude enzyme preparations from the other serotype a (strains HS-1 and AHT) and d organisms (strains KIR, OMZ176, and OMZ65) but not with those from serotype b (strains FA-1 and BHT) or c organisms (strains GS-5, Ingbritt, and NCTC 10449). Based upon the antiserum used, the orders of antigenic similarity of the cross-reacting enzymes to the HS-6 enzymes were HS-6 > HS-1 > AHT = KIR = OMZ176 = OMZ65 for dextransucrase and HS-6 = HS-1 > AHT = KIR = OMZ176 = OMZ65 for invertase. It was found that the enzymes from serotype a organisms were not always antigenically homogeneous, as seen between strains HS-6, HS-1, or AHT for dextransucrase, and between the HS group and strain AHT for invertase. Antiserum against the HS-6 dextransucrase markedly inhibited the heterologous dextransucrases of serotype a organisms with the exception of strain HS-1 and d organisms, with or without the addition of dextran.

Journal Article↗
PubMed1974

Purification and properties of dextransucrase and invertase from Streptococcus mutans.

Invertase (beta-d-fructofuranoside fructohydrolase, EC 3.2.1.26) and dextransucrase (alpha-1, 6-glucan: d-fructose 2-glucosyltransferase, EC 2.4.1.5) were purified from the culture fluids of Streptococcus mutans by chromatography on Sepharose 6B and diethylaminoethyl-cellulose followed by treatment with hydroxyapatite. Each of the enzyme preparations gave a single band when analyzed by either polyacrylamide gel electrophoresis or immunodiffusion. The antigenic determinant of invertase was different from that of dextransucrase on immunodiffusion. The pH optima were 5.25 for invertase and 5.75 for dextransucrase, and the K(m) values were 20 mM for invertase and 2.0 mM for dextransucrase. The molecular weights determined by sodium dodecyl sulfate gel electrophoresis were 160,000 for invertase and 170,000 for dextransucrase. The data obtained suggest that the dextransucrase had dextran-synthesizing activity and invertase-like activity.

Carbon Radioisotopes↗
PubMed1974

Acceleration of dextransucrase activity of Streptococcus mutans by secretory immunoglobulin A.

The effect of immunoglobulins on the activity of dextransucrase purified from Streptococcus mutans strain HS-6 is described. When human salivary immunoglobulin A (IgA) or colostral IgA, either natured or denatured, was incubated with dextransucrase, the rate of the dextran synthesis was markedly accelerated, whereas human serum IgA or IgG neither accelerated nor inhibited the enzyme activity. The results suggest that a portion unique for secretory IgA, the secretory component, might be related to the enzyme acceleration. On the other hand, specific rabbit antiserum against the dextransucrase inhibited completely dextran synthesis by the enzyme.

Animals↗
PubMed1973

Source of neuraminidase in human whole saliva.

Whole saliva specimens from eight healthy human adults were examined for neuraminidase. The presence of two types of neuraminidase in four samples out of eight was demonstrated by means of polyacrylamide gel electrophoresis and sucrose density gradient centrifugation. One type is soluble and the other an insoluble, perhaps particle-bound, enzyme. The pH optima were 5.8 for the former and 5.0 to 5.3 for the latter. However, the soluble enzyme could not be detected in the other four saliva specimens which showed low activity. A comparative study of the salivary and other neuraminidases was carried out. It was found that both salivary neuraminidases were closely similar to the enzymes in submandibular-sublingual secretions and in human liver, but not to the oral streptococcal enzymes. The results suggest that the salivary neuraminidases might originate from cells such as epithelial cells or polymorphonuclear leukocytes, or both, in the oral cavity.

Centrifugation, Density Gradient↗
PubMed1973

Inhibition of enzymes by human salivary immunoglobulin A.

Human whole saliva inhibited bacterial neuraminidases and the inhibition was found to reside in the salivary IgA fraction. Further, salivary immunoglobulin (Ig)A inhibited various bacterial enzymes and toxins: neuraminidases from Streptococcus mitis, Streptococcus sanguis, and Clostridium perfringens, hyaluronidase and chondroitin sulfatase from oral bacteria, diphtheria toxin, and streptolysin O. The inhibitory activity of salivary IgA did not correlate with that of serum on the basis of minimum inhibitory dose. A small amount of salivary IgA was required to inhibit oral bacterial neuraminidases, whereas a large amount was required to inhibit other bacterial neuraminidase. Therefore, it is concluded that the absence of neuraminidase activity of oral bacteria in whole saliva may be due to specific inhibition by salivary IgA.

Animals↗
PubMed1972

Effect of morphine on the cerebral contents of metabolites of dopamine in normal and tolerant mice: its possible relation to analgesic action.

1. The administration of an analgesic dose (10 mg/kg, s.c.) of morphine increased the concentrations of the dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the brains of normal mice, and the time course of the change in the DOPAC concentration corresponded approximately to that of morphine analgesia. The increase in the concentration of the DOPAC induced by morphine (20 mg/kg, s.c.) was completely suppressed by nalorphine (2 mg/kg, s.c.) given 5 min after the morphine administration.2. In morphine-tolerant mice the concentrations of DOPAC and HVA in the brain did not differ from those observed in normal mice, and the increase in the concentrations of DOPAC and HVA in brain after the acute administration of morphine no longer occurred.3. Nalorphine (2 mg/kg) given alone did not cause any change in brain DOPAC and HVA concentrations in normal mice.4. The morphine-induced increase in DOPAC and HVA concentrations in the brain are discussed in the light of the hypothesis that dopamine might participate not only in the extrapyramidal motor system but also in the sensory mechanisms of the brain.

Analgesia↗