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Biomedical subjects

H Osaki

Publications and source records attributed to H Osaki.

At least 37 records · Page 2Linked to original sources
PubMed1984

Toxoplasmacidal activity of Obioactin derived from hydrolyzed Toxoplasma immune bovine serum in heterologous cell cultures.

Serum samples were collected from Toxoplasma-infected cattle after challenge and 24 h after Toxoplasma lysate injection. They were hydrolyzed with proteinase, HCl and NaOH. Then substances 3,000 to 5,000 in molecular weight were obtained from fractionation by chromatography. Native serum was collected from cattle immune only to Toxoplasma was affected in homologous bovine monocytes. Of the hydrolyzed fractions, one termed Obioactin inhibited the growth of Toxoplasma in heterologous cells, such as mouse macrophages and kidney cells, canine monocytes, and human heart and brain cells. Its toxoplasmacidal activity was presumed to be derived from its non-specific cell potentiating effects. In mice immunized to Toxoplasma peritoneal macrophages released about 10 times as much superoxide (O-2) and hydrogen peroxide (H2O2) as glycogen-elicited macrophages in normal mice. The release of O-2 and H2O2 from glycogen-elicited and resident macrophages in normal mice showed a tendency to increase up to 72 h of incubation with 0.5% Obioactin . No changes in the O-2 and H2O2 release were found in kidney cells during the period of incubation with Obioactin . In those immunized mice activated macrophages and kidney cells inhibited the intracellular multiplication of Toxoplasma parasites remarkably. It was suggested that the increase in O-2 and H2O2 generating activity in the macrophages might be associated with the enhancement of antitoxoplasmatic activity. The mechanism of inhibition of Obioactin , however, might be different from that of mouse macrophages on the multiplication of Toxoplasma in mouse kidney cells.

Animals↗
PubMed1984

Studies on the activity of Obioactin with acetylspiramycin on mice infected with Toxoplasma gondii.

In acutely infected mice, acetylspiramycin (ASPM) administered in combination with Obioactin , or sulfamethoxypyrazine ( SMPZ ), prevented Toxoplasma organisms from encysting in the brain and heart tissues. When administered alone, ASPM prevented these organisms from encysting in the heart but not in the brain. All the regimens used failed to reduce the bulk of parasites in the brain and heart tissues of chronically infected mice. Treatment with an ASPM- Obioactin combination, however, brought about the most remarkable reduction, or 52.4%, of the cyst count in the brain of all the methods of treatment applied. Light and electron microscopy of the mice with chronic Toxoplasma infection revealed no changes in the brain or heart tissue of the ASPM- Obioactin treated mice and degenerative changes in the cyst wall and bradyzoites and a remarkable increase of microglias with cysts in the brain in some of these mice.

Animals↗
PubMed1981

Transmission and scanning electron microscopic studies of the micronemata of Trypanosoma gambiense.

The structure of micronemata arising from the surface of the bloodstream form of Trypanosoma gambiense was studied by electron microscopy. In order to produce micronemata, trypanosomes were incubated in either 1) phosphate buffered saline supplemented with glucose (PBSG), 2) immune mouse serum or 3) PBSG after passage through a DEAE-cellulose column. Electron microscopic examination of the parasite revealed the presence of thread-like micronemata arising from the anterior end and from the flagellar pocket regardless of the incubation conditions. Negative staining revealed a distinct peripheral fringe layer with nodular protrusions covering the entire surface of the micronema. The distribution and number of intramembrane particles (IMP) on the P and E faces of the micronema were similar to those of the flagellum of T. gambiense, indicating a close relationship between the membrane structure of the micronema and the flagellum. Micronemata became fragmented and adhered to each other after incubation of the parasite in the media for 12 h. Since micronemata tend to have the characteristics of adhesiveness and fragmentation, fragments of these structures might adhere to various host organs. Dispersal of potential antigenic material might be responsible, in part, for the induction of the host immune response.

Adhesiveness↗
PubMed1981

Agglutination antibody responses to Trypanosoma gambiense homogenate in mice treated with dextran sulfate 500 and carrageenan.

Dextran sulfate 500 and carrageenan, sulfated polysaccharides, have been considered as macrophage-toxic giving profound effects on the immune response. This work deals with agglutination antibody responses to T. gambiense homogenate in mice treated with dextran sulfate 500 and carrageenan. Antibody responses to the first immunization were suppressed in mice treated with the agents before the first immunization but reverse was the case with the response to the second immunization. These suppression and enhancement appeared to be dependent on the timing of treatment in regard to the time of the first immunization. The enhanced antibody response was abolished by either treating the mice with anti-thymocyte serum or transferring of spleen cells treated with anti-thymocyte serum into mice. Thus, the enhancement of antibody response is seemingly attributable for the most part to potent memory T cells induced by treatment with the agents.

Agglutination Tests↗
PubMed1981

In situ microfluorometry of whole kinetoplast and nuclear DNA in a single cell of Trypanosoma gambiense and Trypanosoma cruzi.

In situ microfluorometry of whole kinetoplast DNA (K-DNA) and nuclear DNA (N-DNA) from a single trypomastigote cell of Trypanosoma gambiense (strain Wellcome) and Trypanosoma cruzi (strain Tulahuen) was attempted by using the microfluorometer combined with a photon counter. The results obtained were summarized as follows; 1. The K-DNA value of 2K 1N (2 kinetoplasts and 1 nucleus) T. gambiense was about twofold as much as that of 1K 1N on. 2. The N-DNA value of 2K 1N T. gambiense was a little less than two times as much as that of 1K 1N T. gambiense, showing that the N-DNA had already bee increased nearly twofold before the nuclear division was initiated. 3. The K-DNA value of 1K 1N T. cruzi was about fivefold as much as that of 1K 1N T. gambiense. The N-DNA value was contrarily lower than that of T. gambiense, being approximately 70% of the latter. 4. Percent K-DNA/N-DNA value was, in average, about 7 in either 1K 1N or 2K 1N T. gambiense and about 50 in T. cruzi. 5. Percent K-DNA/N-DNA value in individual trypomastigote cell was variable, showing that the increase of K-DNA and N-DNA was not synchronized at least in the two species of trypanosomes used here. 6. The fact that K-DNA and N-DNA values varied from cell to cell although they do not divide, suggested the possibility of DNA increase in the trypomastigote of T. cruzi.

Animals↗
PubMed1980

Effects of dextran sulfate 500 on protective responses to sublethal Trichomonas foetus infection in mice.

In order to analyze the host-parasite interactions in experimental trichomoniasis, the growth of Trichomonas foetus in the peritoneal cavity and changes in the peritoneal exudate cells were followed in mice treated with dextran sulfate 500 (DS 500), a known macrophage-toxic agent. Light microscopic observation showed that DS 500 treatment induced degeneration of peritoneal macrophages within about 48 hr after the treatment and the damaged macrophages did not phagocytize the parasites, whereas peritoneal neutrophils and lymphocytes were not affected by the drug. In the DS 500-treated mice, growth of parasites in the peritoneal cavity was accelerated and a high susceptibility of the mice to T. foetus infection was observed. These results indicate that macrophages play the most important role among the peritoneal exudate cells in resistance to T. foetus infection, especially during the early stage of infection.

Animals↗
PubMed1979

Protective immune response in mice immunized with antigens from Trypanosoma gambiense-infected mouse blood.

Immunogenicity and property of antigens obtained from Trypanosoma gambiense-infected mouse blood (IMP) were examined. A strong vaccine effect against intravenous challenges with 3 x10(3) parasites given on study day 3, 5, or 14 (day 0 = immunization) was observed in mice immunized with a combination of IMP (2 mg protein/mouse) and Freund's complete adjuvant (FCA). But when the challenge was given on day 21 or 30, per cent survival in mice dropped to the 20- and 40-per cent level, respectively. Among fractioned components of IMP, IMP-1, IMP-2, and imp-3, by gel filtration with Sephadex G-200, all of the mice immunized with IMP-1 antigen alone or together with FCA and challenged on day 5 were able to conquer intraperitoneal challenges with 1 x10(2) parasites. Mice immunized with IMP-2 or IMP-3 died within 6 days after challenge. Moreover, protection efficacy shown by IMP-1p (144,000 xg sediment of IMP-1) antigen in mice was similar to that by IMP and IMP-1 antigens. IMP-3 yielded a single precipitin line against mouse anti-IMP serum by Ouchterlony double diffusion method but this response was eliminated when the antiserum was absorbed by IMP-1p. No precipitin line was identified between mouse anti-IMP serum and IMP-1 or IMP-2. From electron microscopic observations, elements of IMP-1 and IMP-1p are possibly corresponded to the fragments of filopodia of the parasites.

Agglutination Tests↗
PubMed1979

In situ microspectrofluorometry of nuclear and kinetoplast DNA in Trypanosoma gambiense.

Using a spectrofluorometer with the Zeiss Universal Micro-Spectrophotometer 1 (UMSP 1), both nuclear and kinetoplast DNA (N-DNA and K-DNA) in the trypomastigote form of Trypanosoma gambiense (Strain Wellcome) were measured in situ without being extracted. As the fluorescent dye, ethidium bromide was preferably employed because there was a very marked increase in the ethidium fluorescence when the dye was intercalated between the base paires of the DNA helix. According to this method, it became possible to demonstrate the existence of double-stranded DNA in both nucleus and kinetoplast clearer than before.

DNA↗