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Biomedical subjects

H Fujihara

Publications and source records attributed to H Fujihara.

44 records · Page 3Linked to original sources
PubMed1992

[Digital imaging microscopy for intracellular Ca2+ in cultured single rat vascular smooth muscle cells using fluorescent Ca2+ indicator "fura-2"].

We presented the principle and methodology of digital imaging microscopy for intracellular Ca2+ in cultured single vascular smooth muscle cells of the rat using fluorescent Ca2+ indicator "fura-2". The methods seemed useful for studying the physiological and pathological phenomena in a single smooth muscle cell. Analysis of the spatial and temporal dynamics of intracellular Ca2+ might be crucial for studying the active sites of vasoactive or anesthetic drugs in a vascular smooth muscle cell as well as for understanding pathophysiology of the arterial spasm.

Animals↗
PubMed1989

Immunologic significance of diverse specificity of monoclonal antibodies against mannans of Candida albicans.

Two agglutinating IgM mAb against mannan Ag of Candida albicans strains were investigated for their specificity. The agglutinating patterns of both mAb with a panel of stationary phase of yeast cells of standard strains did not match those of any known polyclonal antibody (PAb) factors. The reactive patterns of both mAb for a given panel of 202 isolates of seven Candida species and the mode of competitive binding between mAb and a PAb factor, as determined by a combination of direct and indirect immunofluorescence staining, demonstrated that the two mAb were a part of PAb factor 4 (a prescribed reactive pattern of adsorbed PAb) but were different from each other in their specificity. The thereby designated mAb 4b and 4c were tested under PAb factor 4-positive Candida strains and further division into two to three serotypes of each species were made. 1H-Nuclear magnetic resonance spectra (500 MHz) of purified neutral mannans from strains of each serotype showed that although the 1H-nuclear magnetic resonance spectra of mannans from two subtypes of C. albicans serotype A and from each of two serotypes of Candida guilliermondii and Candida glabrata were identical or similar, the two mAb were still able to distinguish their fine determinant structures. Our findings suggest that mAb with entirely identical specificity cannot be produced against even the same determinant groups of mannan. In addition, the fact that microheterogeneity may occur without limit in the mannans of the strains suggests that antibodies with unlimited diverse specificities are produced directed against these antigenic varieties as well.

Agglutination Tests↗
PubMed1988

Molecular interactions in intermediate and transition states in the self-stimulated inhibition of enzymes.

Di-isopropyl fluorophosphate (DFP) and other organophosphorus inhibitors recruit the catalytic power of their target enzymes: the enzyme catalyzes its own irreversible phosphorylation. The magnitude of the catalytic acceleration can approach the factor by which the enzyme catalyzes its own acylation by natural substrates. The reaction of DFP with five serine proteases [chymotrypsin, elastase, dipeptidyl peptidase IV (DP IV), subtilisin and thermitase] exhibits in all cases the same pH dependence as does enzyme acylation by natural substrates. Chymotrypsin and elastase form a "fast" class of enzymes which react about ten-fold faster than the other three "slow" enzymes. All enzymes show k(HOH)/k(DOD) of about 2 but the proton inventory indicates one-proton character for "slow" enzymes and multiproton character for "fast" enzymes. Enthalpies of activation are about 33 kJ/mol (subtilisin, "slow") and 10 kJ/mol (elastase, "fast"). Entropies of activation are about -120 J.T-1.mol-1 (subtilisin, "slow") and -175J.T-1.s-1 (elastase, "fast"; T = temperature in K).

Enzyme Inhibitors↗
PubMedDate not supplied

Arginine vasopressin increases perinuclear [Ca2+] in single cultured vascular smooth muscle cells of rat aorta.

The effects of arginine vasopressin (AVP, 10(-7) M) on the spatial dynamics of intracellular [Ca2+] in single cultured smooth muscle cells of the rat aorta were studied by digital imaging microscopy using the fluorescent Ca2+ indicator fura-2. The nuclear and cytosolic regions were distinguished by the fluorescent image excited at 380 nm. Changes in intracellular [Ca2+] were expressed as percent increases in the ratios of fluorescence intensity at 500 nm excited by 340 and 380 nm. AVP increased the nuclear and cytosolic [Ca2+] in Ca(2+)-containing (control) (285 +/- 27 and 172 +/- 22%, respectively) or Ca(2+)-free (203 +/- 26 and 121 +/- 15%, respectively) solutions. However, caffeine (20 mM) and ryanodine (20 microM) greatly attenuated the [Ca2+] increase induced by AVP in both regions (61 +/- 21 and 42 +/- 15%, respectively). On the ratio image, the nuclear region was discriminated from other regions at the peak response to AVP in preparations treated with caffeine and ryanodine, whereas the outline of the nuclear region was indistinct in untreated preparations. The finding implies that caffeine- and ryanodine-responsive Ca2+ storage sites may exist in the region surrounding the nucleus. The results suggest that the region surrounding the nucleus may be one of the important Ca2+ storage sites with regard to the responses of rat aortic smooth muscle cells to AVP.

Animals↗