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H Shinoda

Publications and source records attributed to H Shinoda.

At least 109 records · Page 6Linked to original sources
PubMed1982

[Experimental studies on the ultrastructure and chemical composition of enamel in dental fluorosis].

Young growing rats were maintained on drinking water containing different amounts of fluoride (0, 45, 100 and 113 ppm of F) for 70 days. Ultrastructural and chemical changes in the incisor enamel were investigated using scanning electron microscopy combined with a microincineration technique with a low temperature asher and by means of chemical analyses. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core as well as in the interprismatic region was lower than that of control animals. The organic constituents appeared to increase in those regions. These changes were evident in the outer enamel layer. Such results following fluoride administration were confirmed by chemical analyses, that is, calcium and inorganic phosphorus contents in the enamel decreased, whereas the amount of organic carbon in the enamel increased as the fluoride concentration in drinking water became higher. The results obtained in the present study appear to indicate that fluoride interferes with the process of enamel maturation. The mode of fluoride action was discussed with special reference to the recent findings about enamel formation.

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PubMed1978

Scanning electron microscopical study on the fluorosis of enamel in rats.

Sixteen 28-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. The changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.

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PubMed1977

Inhibition of macrophage-mediated cytolysis by lipoproteins from cell-free tumorous ascites.

Cell-free ascites from syngeneic MM46 tumor-bearing C3H/He mice inhibited the antibody-dependent macrophage-mediated tumor lysis in vitro and the inhibitiory activity increased with the period of tumor bearing. Thus, the inhibitory activity was demonstrated at the effector cell level. Three fractions of lipoprotein and a protein-rich fraction were prepared from the cell-free ascites by sequential flotation. Among these, the very low density (p less than 1.006) and low density (1.006 less than p less than 1.063) lipoprotein fractions inhibited tumor lysis mediated by activated macrophages and syngeneic antitumor antibody, whereas the high density (1.063 less than p less than 1.21) lipoprotein and the protein-rich infranatant fractions did not. This inhibitory activity at the effector cell level may be due to functional depression of macrophages by lipoprotein fractions.

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PubMed1977

Protective effect of syngeneic antitumor serum on mammary tumor in a syngeneic host.

The possibility of passive immunotherapy was examined using syngeneic antitumor serum, which could lyse tumor cells in co-operation with immune or activated macrophages. Intraperitoneal injection of syngeneic antiserum into mice soon after inoculation of MM46 tumor cells clearly suppressed peritoneal or subcutaneous tumor growth. However, the antiserum did not suppress an established tumor. The tumor-specific synantibody responsible for the protection was shown by gel filtration to be in the IgG fraction, not the IgM fraction.

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PubMed1977

Passive immunotherapy of established tumors with syngeneic antitumor serum in combination with immunopotentiators.

The possibility of passive therapy of 6 approximately 8-day established tumors with syngeneic antitumor antiserum was tested using (1) combination of the antiserum and immunopotentiators, (2) combination of the antiserum and inflammatory agents, and (3) repeated injections of antiserum. Therapeutic effect on an ascites tumor was seen using antiserum in combination with BCG or lipopolysaccharide, or less clearly with carrageenan. Combinations of antiserum and PS-K, histamine, or croton oil did not have a synergistic therapeutic effect, but repeated injection of a small amount of antiserum did have a therapeutic effect on established peritoneal and subcutaneous tumors.

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PubMed1976

Antibody-dependent macrophage-mediated cytolysis in a murine syngeneic tumor system.

Peritoneal immune macrophages from C3H mice immunized against syngeneic MM46 ascites tumor cells specifically lysed these tumor cells in the presence of immune sera in vitro. An active factor(s) essential for macrophage-mediated cytolysis was purified nonspecifically by gel filtration and then three types of ion-exchange column chromatography. One factor was a specific antibody belonging to the IgG2 a subclass. Neither immune macrophages nor the syngeneic antitumor antibody alone had a cytolytic action on the target cells. Thus, we named the reaction antibody-dependent immune macrophage-mediated cytolysis. The immune macrophages apparently destroyed the sensitized tumor cells in vitro by a nonphagocytic form of cell-contact and this type of cytolysis was independent of a complement. No evidence was obtained for a soluble cytotoxic factor released on interaction of immune macrophages with sensitized tumor cells. Living immune macrophages were essential for the cytolytic action and their activity depended on contractile microfilaments and protein synthesis as revealed by studies with specific inhibitors.

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PubMed1976

Two-step mechanism of macrophage-mediated tumor lysis in vitro.

Normal peritoneal macrophages from C3H/He mice could not lyse syngeneic MM46 tumor cells in co-operation with syngeneic antitumor antibody. Thus, normal macrophages could not effectively participate in the antibody-dependent macrophage-mediated tumor lysis in vitro. However, after activation in vivo by stimuli, such as lipopolysaccharide, BCG, or glycogen, macrophages could co-operate with antitumor antibody in cytolysis of target cells. In the cytolysis nonspecific activation of normal macrophages was an essential first step, followed by specific tumor lysis in the presence of an antitumor antibody (second step). Immune macrophages from resistant mice were apparently equal in functional state to activated macrophages. A two-step mechanism of tumor lysis in vitro in a syngeneic mammary tumor system is proposed.

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PubMed1975

Effect of long-term administration of fluoride on physico-chemical properties of the rat incisor enamel.

Rats were maintained on drinking water containing different amounts of fluoride (0, 9, 23 45, 68, and 113 ppm) for 70 days. Physico-chemical properties of the incisor enamel were examined after fluoride administration, using contact microradiography, histochemistry, and microhardness tests. The tooth enamel formed during high fluoride exposure showed marked hypocalcification. Much of organic substance in the enamel seemed to have been retained. In addition, the microhardness of enamel showed a marked decrease. These changes were most prominent in the outer region of enamel and were proportional to the concentration of fluoride administered. Such changes following fluoride administration indicated inhibition of enamel maturation, i.e., an inhibition of the progressive depposition of minerals and/or in inhibition of organic matrix withdrawal by ameloblasts. Enamel seemed more affected by fluoride than dentine.

Animals↗
PubMed1975

Co-operation between macrophages and a factor from lymphocytes in tumor lysis in vitro.

Peritoneal cells from C3H/He mice immunized against syngeneic MM46 ascites tumor cells specifically lysed these tumor cells in vitro, while spleen cells or lymph node cells from immunized hosts were completely ineffective. The effector cells differed from lymphocytes in their morphological characteristics, property of adherence, phagocytic activity, and sensitivity to anti-theta serum. The cytolytic action of the peritoneal cells was not due to cytotoxic lymphocytes, but to macrophages. These macrophages lysed tumor cells in co-operation with a factor derived from immunoglobulin-bearing lymphocytes. Neither macrophages from immunized hosts nor the factor from lymphocytes alone had a cytolytic action on the target cells. Normal macrophages showed some cytolytic activity in the presence of the factor from lymphocytes.

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