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Biomedical subjects

T Hamano

Publications and source records attributed to T Hamano.

At least 145 records · Page 8Linked to original sources
PubMed1985

Separate determination of ethylenediaminetetraacetic acid and its calcium chelate in foods by colorimetry.

A simple colorimetric method is described for the separate determination of ethylenediaminetetra acetic acid (free EDTA) and its calcium chelate (Ca-EDTA) in commercial foods. The underlying principle of the method is that free EDTA is adsorbed by a cation exchange column, but Ca-EDTA is not under weak alkaline conditions. The sample was homogenized with 0,1 n-NaOH and then subjected to equilibrium dialysis against 0,02 n-NaOH at ambient temperature for a definite time (not less than 12 h). An aliquot of the dialysate was measured into a beaker. After the pH of the solution had been adjusted to 8.5 it was applied to a pre-packed cation-exchange column (Amino-form). Free EDTA was adsorbed by this column, whilst Ca-EDTA passed through it without any loss. For assay of Ca-EDTA, the pH of the eluate was adjusted to 2.5, followed by the addition of an excess amount of CuSO4 to convert Ca-EDTA into Cu-EDTA. This solution was then divided into two portions of equal volume. One portion was subjected to the assay of free copper ions, and the other to the assay of total (the sum of free and chelated) copper ions. The difference between the two values is a measure of Ca-EDTA. For the assay of free EDTA, EDTA adsorbed by the column was eluted with 0.5 n-acetate buffer (pH 5.0), followed by the treatment in the same manner as in the case of Ca-EDTA.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗
PubMed1985

Colorimetric determination of ethylenediaminetetra-acetic acid in foods.

A simple colorimetric method is described for the determination of ethylenediaminetetra-acetic acid (EDTA) in three kinds of foods. The samples were homogenized with 0.1 N-NaOH, then subjected to equilibrium dialysis against 0.02 N-NaOH. EDTA in the dialyzate was converted into a Cu-EDTA complex by the addition of CuSO4. Afterwards, this solution was subjected to the determination of both free and total (free plus complexed) copper ion. EDTA was calculated from the difference between the absorbances (477 nm) obtained with free and total copper ions. Analyses of mayonnaise, dressings and canned mushroom samples with EDTA added at the 1-mM level showed a recovery of greater than 98%.

Colorimetry↗
PubMed1984

Functional studies on B-cell hybridomas with B-cell surface antigens. III. Differentiative response to phorbol esters.

Phorbol esters have been shown to induce differentiation of human lymphoid cells into the mature stage. Murine lymphocytes, however, have not been found to be induced the terminal differentiation by these products. In this study, TH2.52, a subclone of B-cell hybridomas between M12.4.1 B lymphoma of BALB/c mice and normal B cells of C57BL/6 (B6) mice was treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) and the differentiative effect of TPA was examined. TPA treatment inhibited the spontaneous proliferation of TH2.52 and induced significant IgM secretion by the hybrid. In contrast, M12.4.1 did not develop any IgM secretion when treated with TPA. The differentiative effect of phorbol esters on TH2.52 closely correlated with their tumor-promoting activity. In addition, the differentiative response of TH2.52 to TPA was completely blocked by retinoic acid (RA). Moreover, TH2.52 cells treated with TPA were demonstrated to decrease the expression of Iab, Iad molecules as well as IgM molecules on the cell membrane by analyses of flow microfluorometry (FMF) and quantitative absorption tests. On the other hand, Iad expression of M12.4.1 did not change under the same conditions. The result clearly demonstrates that TH2.52 cells can be induced to differentiate into IgM-secreting cells after treatment with TPA, followed by the decrease in the expression of B-cell surface antigens on the cell membrane.

Animals↗
PubMed1984

Electron microscopic study of intrastromal hydrogel implants in primates.

Three corneas with intrastromal hydrogel implants (surfilcon A) were removed from Green monkey eyes by penetrating keratoplasty and examined by light microscopy, as well as scanning and transmission electron microscopy, in order to assess the tolerance of the primate cornea for this type of synthetic plastic. Placement of these implants in the posterior cornea appears to increase the amount of protrusion into the anterior chamber, which can also be seen clinically on slit-lamp biomicroscopy. Some physiological stress to the cornea was indicated by abnormalities above and below the implant, including thinned epithelium, irregular cell shapes, and vacuolations. It appears that a basement-membrane-like material is produced by keratocytes adjacent to the implant-stroma interface, and that this material fills the spaces and provides some physical continuity between the plastic and the corneal tissue. No inflammatory reaction was seen around the implants, but further long-term studies are necessary to ensure compatibility between the cornea and the implant.

Animals↗
PubMed1984

Functional studies on B cell hybridomas with B cell surface antigens. IV. Direct effects of cytochalasin B on differentiation.

We previously established B cell hybridomas between M12.4.1 B lymphoma of BALB/c mice and normal B cell of C57BL/6 (B6) mice. These hybridomas express Iab, Iad, and IgM molecules on the cell membrane, and can induce the generation of IgM secretion when treated with purified goat anti-mouse-mu antibody (anti-mu) without T cell factors. In this study, TH2.54, a subclone of a B cell hybridoma, was treated with cytochalasin B (CB), a fungal product that disrupts microfilaments, and the direct effect of CB on the proliferation and differentiation of TH2.54 was examined. CB considerably suppressed the spontaneous proliferation of hybrid cells. This product, however, did not inhibit the generation of IgM secretion by TH2.54 treated with anti-mu. Surprisingly, CB could directly induce the development of IgM-secreting cells by TH2.54 at a relatively high frequency. Among cytochalasins, dihydrocytochalasin B (H2CB), cytochalasin C (CC), and cytochalasin D (CD) showed marked effects on the induction of IgM secretion as well as CB. In addition, the differentiative effect of CB was greatly inhibited by N6, O2-dibutyryladenosine 3':5'-cyclic monophosphate (dbc-AMP), but not by N2, O2-dibutyrylguanosine 3':5'-cyclic monophosphate (dbc-GMP). Analysis by flow microfluorometry (FMF), cytotoxicity assays, and quantitative absorption tests demonstrated that CB treatment of TH2.54 resulted in a significant decrease in the expression of Iab, Iad, and IgM molecules on the cell membrane. In contrast, parental M12.4.1 neither generated any IgM secretion nor changed Iad expression on the cell membrane under the same conditions. The present study suggests very strongly that microfilament-microtubule systems are not involved in the differentiative process of TH2.54 induced by anti-mu. The results also indicate that CB can provide the initiative signal for differentiation of TH2.54 into the maturation lineage; this is followed by a significant change in the expression of Ia and IgM molecules on the cell membrane.

Animals↗
PubMed1984

Refractive keratoplasty with hydrogel implants in primates.

Histological examination of primate corneas with hydrogel lenses implanted in intrastromal pockets showed the corneal lamella posterior to the implant protruding into the anterior chamber; these eyes had shown no increase in anterior corneal curvature. In an attempt to obtain a dioptric increase without removing a corneal lamella, relaxing incisions were made in Bowman's layer followed by intrastromal implantation of hydrogel lenses. However, no refractive increase resulted, although six of the seven eyes were optically clear eight months postoperatively.

Animals↗
PubMed1983

IA mutant functional antigen-presenting cell lines.

We describe a protocol for the selection of mutant cells with an altered pattern of Ia antigenic determinants and antigen-presenting properties from a homogeneous population of functional antigen-presenting cells (APC). The APC line used in this work was obtained by fusing lipopolysaccharide-stimulated B cells from (BALB/c x A/J)F1 donors with cells from the M12.4.1 BALB/c B lymphoma cell line. The resulting hybridomas, including TA3, retained the potent antigen-presenting activity of the parental B lymphoma line and expressed Ia antigens and immune response gene-determined antigen-presenting properties of the A/J type. Mutants of TA3 were obtained by subjecting the cells to negative immunoselection with one monoclonal anti-(alpha) 1-Ak antibody and complement followed by positive immunoselection via electronic cell sorting with a second monoclonal alpha I-Ak or alpha I-Ek antibody. Two types of mutants were obtained. One, A8, appeared to have undergone a fairly limited alteration, since it lost only some of the I-Ak antigenic determinants; the second type appeared to have lost the entire I-Ak molecule but to have retained the I-E molecule. Functional studies with the A8 mutant demonstrated that the loss of a limited number of I-Ak determinants correlated with the loss of a specific I-Ak-encoded restriction element, since A8 failed to present a specific antigen, hen egg lysozyme (HEL), to a HEL-specific I-Ak-restricted T cell hybridoma but retained some capacity to present a second antigen, poly(Glu60Ala30Tyr10) (GAT), to a GAT-specific I-Ak-restricted T cell hybridoma. These results indicate that Ia antigens are the products of immune response gene loci. The availability of such mutants should allow an examination of the relationship between the structure of an Ia molecule and the antigens with which it is co-recognized by T cells.

Animals↗
PubMed1983

Functional studies on B cell hybridomas with B cell surface antigens. I. Effects of anti-immunoglobulin antibodies on proliferation and differentiation.

B cell hybridomas with Ia and IgM molecules on the cell membrane were treated with either purified goat anti-mouse mu antibody (anti-mu) or monoclonal rat anti-mouse IgM antibody (anti-IgM). The spontaneous uptake of [3H] thymidine by these cells was markedly inhibited by both reagents. These hybrid cells could be induced to differentiate into IgM-secreting cells in the presence of these reagents at high frequency. Furthermore, the induction of IgM secretion by B cell hybridomas treated with these antibodies was completely T cell independent, and cell division was not required for the differentiative response to anti-mu. In addition, F(ab')2 fragments of anti-mu showed more effects on proliferation and differentiation of these cells than intact anti-mu. Interestingly, TH2.54, a subline of B cell hybridomas, could generate IgG2a production as well as IgM when incubated with anti-mu. These findings suggest very strongly that the interaction of either goat anti-mu or monoclonal rat anti-IgM with surface IgM molecules on the cell membrane of the B cell hybridomas inhibits in vitro spontaneous proliferation, and results in providing signals for differentiation into Ig-secreting cells without T cell factors.

Animals↗
PubMed1983

Functional studies on B cell hybridomas with B cell surface antigens. II. Ia molecules on the cell membrane and the differentiative response to anti-mu antibody.

TH 2.52, a subline of the B cell hybridoma with Iab, Iad, and IgM molecules on the cell membrane, was treated with F(ab')2 fragments of purified goat anti-mouse mu antibody (anti-mu), and the change in the expression of surface Ia molecules was determined by microcytotoxicity assays, quantitative absorption tests, and analyses of flow microfluorometery (FMF). We have previously reported that TH 2.52 cells can markedly generate IgM after stimulation with anti-mu without T cell factors. In the present studies, it was shown that the expression of surface Iab molecules on TH 2.52, originated from normal B cells of C57BL/6 (B6) mice, significantly decreased after treatment with anti-mu. In contrast, Iad molecules derived from M12.4.1 lymphomas did not change under the same conditions. These results indicate that cross-linking of anti-mu with surface IgM molecules on TH 2.52 provides signals for differentiation into IgM-secreting cells; this is followed by a decrease in the expression of Iab molecules on the cell membrane. Furthermore, monoclonal anti-Ia antibody (anti-Ia) did not inhibit the generation of IgM-secreting cells by TH 2.52 cells treated with anti-mu. In addition, la- sublines of TH 2.52 obtained after mutagenesis with ethyl methanesulfonate (EMS), as well as the original TH2.52, could differentiate into IgM-secreting cells in the presence of anti-mu. These findings suggest very strongly that la molecules on the cell membrane are not required for the induction of IgM secretion by B cells treated with anti-mu.

Animals↗
PubMed1983

Effects of contact lens wear on mitosis of corneal epithelium and lactate content in aqueous humor of rabbit.

Various types of contact lenses, i.e., poly-methyl-methacrylate hard lenses, poly-2-hydroxyethyl-methacrylate soft lenses and two kinds of gas-permeable hard lenses with different permeabilities to oxygen, were placed on one eye of the albino rabbit for varying lengths of time. Using the fellow eye as the control, studies were carried out of the effects of the lens wear on the mitosis in the corneal epithelium and the lactate concentration in the aqueous humor. The contact lens wear suppressed the mitosis and increased the concentration of aqueous lactate, the degree of changes being greater as the permeability of the lens to oxygen decreased and the period of wear became longer.

Animals↗
PubMed1982

I region-restricted antigen presentation by B cell-B lymphoma hybridomas.

The activation of T lymphocytes for many responses requires interaction with specialized antigen presenting cells (APC) which express I region associated (Ia) antigens. Cells of the monocyte-macrophage lineage and the recently described dendritic cell have been shown to be effective APC. Antigen-specific T cells appear to recognize a complex of antigen and Ia molecules on the surface of the APC and such joint recognition is the basis of the restriction of T-cell activation due to the major histocompatibility complex. The Ia molecules appear to be Ir gene products. However the biochemical nature of antigen presentation has been difficult to approach largely because of problems in obtaining sufficient numbers of highly purified APC. Although several Ia antigen-positive B lymphoma cell lines, which have proved very effective APC, have been recently described, they have all been of the same H-2d haplotype. We report here on hybridomas produced by fusion of normal C57BL/6 (B6) B cells (H-2b) to a hypoxanthine guanosine phosphoribosyl transferase (HGPRT) deficient variant of one of these lymphoma cell lines. The hybridomas appear to express functional Ia molecules of both parental cell haplotypes. Such cloned somatic cell hybrids should prove useful in studying the properties of Ir genes and Ia molecules in antigen presentation.

Animals↗
PubMed1982

Tissue distribution and anti-inflammatory activity of corticosteroids incorporated in lipid emulsion.

Dexamethasone palmitate was incorporated into a lipid emulsion (Intralipid, Intralipos) and was injected into rats, and its distribution in the organs and tissues and its anti-inflammatory effects were compared with those of free dexamethasone disodium phosphate. The distribution patterns of [3H] dexamethasone were markedly different between the 2 preparations in 3 hours after intravenous administration. Dexamethasone palmitate given as a lipid emulsion showed a much higher concentration in the blood, spleen, and inflamed tissues (carrageenan oedema), whereas dexamethasone sodium phosphate had a high concentration in the muscles. The anti-inflammatory activity of both preparations given intravenously was evaluated by using the preformed carrageenan granuloma pouch method. The anti-inflammatory activity of lipid emulsion dexamethasone was 5.6 times as potent as an equivalent amount of free dexamethasone. These results may indicate that corticosteroids which are incorporated in lipid emulsions are taken up by the reticuloendothelial system and some inflammatory cells much more than are free corticosteroids; thus they have a stronger anti-inflammatory activity. The clinical use of lipid emulsion corticosteroids for certain types of diseases is suggested.

Animals↗