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Biomedical subjects

T Sakagami

Publications and source records attributed to T Sakagami.

69 records · Page 4Linked to original sources
PubMedDate not supplied

Branch retinal vein occlusion in the right eye and retinal hemorrhage in the left in a patient with classical Tsutsugamushi disease.

PURPOSE: To report branch retinal vein occlusion and retinal hemorrhages associated with tsutsugamushi disease. METHODS: Case report of a 60-year-old woman who complained of fever, chills, headache, lymphadenopathy, and blurred vision in the right eye following an insect bite to the lower right forehead. RESULTS: Serological findings showed elevated titers for the strains of Rickettsia tsutsugamushi. Ophthalmologic examination disclosed bilateral conjunctival injection, flame-shaped hemorrhage in her right fundus, and scattered hemorrhage in her left fundus. Fluorescein angiography demonstrated dye leakage and dilation of capillaries. CONCLUSIONS: Branch retinal vein occlusion associated with classical tsutsugamushi disease, as demonstrated in our patient, may be rare.

Antibodies, Bacterial↗
PubMedDate not supplied

Effect of cobalt ion on radical intensity and cytotoxic activity of antioxidants.

The effect of CoCl2 on the cytotoxic activity of various antioxidants against human oral tumor cell lines (HSC-2, HSG) and normal human gingival fibroblasts (HGF) was investigated. Noncytotoxic concentrations of CoCl2 significantly reduced the cytotoxic activity of sodium ascorbate, gallic acid, epigallocatechin gallate (EGCG), curcumin and dopamine, but not that of sodium 5,6-benzylidene-L-ascorbate (SBA) and benzaldehyde. Among these compounds, benzaldehyde showed the most prominent tumor-specific cytotoxic action. ESR spectroscopy showed that these antioxidants produced radicals under alkaline condition and that their radical intensity was transiently enhanced and finally disappeared by addition of CoCl2. Antioxidants which are sensitive to CoCl2 generally had higher cytotoxic activity and oxidation potential (measured by NO monitor) and addition of CoCl2 significantly reduced their oxidation potential. The present study suggests that cobalt ion stimulates the oxidation of antioxidants to their inactive products.

Antioxidants↗
PubMedDate not supplied

Experimental gastric carcinogenesis related to Helicobacter pylori.

In this paper, we present our research on the lipid A of Helicobacter pylori, an experimental study using the Mongolian gerbil model and experimental carcinogenesis using the mouse model to evaluate roles of host factors and bacterial factors which are related to the pathogenicity of Helicobacter pylori including gastric carcinogenesis. Future study on bacterial factors and host factors may give more insight into the role of Helicobacter pylori in gastric carcinogenesis.

Animals↗
PubMedDate not supplied

Hypochlorite scavenging activity of polyphenols.

Chemiluminescence, generated by the mixture of sodium hypochlorite solution and luminol, was completely eliminated by polyphenols, such as natural lignins, phenylpropenoid monomers and polymers, and epigallocatechin gallate. On the other hand, hypochlorite scavenging activity of polysaccharides, such as PSK (Krestin) and Schizophyllan, was relatively weak. Human myelogenous leukemic cell lines (HL-60, ML-1) showed higher production of active oxygen(s) (detected by luminol chemiluminescence) and iodination capacity, than six other cultured cell lines. Since lignin did not completely eliminate the active oxygen production by HL-60 cells, possible stimulation of hypochlorite production by lignin was suggested.

Antineoplastic Agents↗
PubMedDate not supplied

Endonuclease activity and induction of DNA fragmentation in human myelogenous leukemic cell lines.

When four human myelogenous leukemic cell lines (HL-60, ML-1, U-937, THP-1) were exposed to either ascorbic acid, hydrogen peroxide, etoposide, tumor necrosis factor, hyperthermia or UV irradiation, their growth inhibition and oligonucleosome-size DNA fragmentation were induced. Non-myelogenous leukemic cell lines (MOLT-4, K-562) were similarly sensitive to ascorbic acid and hydrogen peroxide, but relatively resistant to etoposide, TNF, hyperthermia and UV irradiation. Furthermore, these treatments except for UV irradiation, did not induce any apparent DNA fragmentation in MOLT-4 and K-562 cells. An autodigestion experiment revealed that all of these six cell lines contained divalent cation-independent endonuclease activity as a major endonuclease. The ability of this endonuclease to produce oligonucleosome-size DNA fragmentation was stimulated at acidic, but not at neutral pH. Since this enzyme activity was not detected in the lysosomal enzyme-free nuclei, prepared from all six cell lines, the cytoplasmic localization of this enzyme was suggested. The results suggest that the endonuclease activity might be differently regulated between myelogenous and non-myelogenous leukemic cell lines.

Apoptosis↗
PubMedDate not supplied

Induction of DNA fragmentation in human myelogenous leukemic cell lines by sodium 5,6-benzylidene-L-ascorbate and its related compounds.

High-performance liquid chromatography revealed that sodium 5,6-benzylidene-L-ascorbate (SBA), dissolved in distilled water, was gradually decomposed into ascorbic acid and benzaldehyde. Among these three compounds, ascorbic acid showed the most potent cytotoxic activity. The cytotoxic activity of each compound was significantly reduced during degradation in culture medium. Agarose gel electrophoresis and fluorometric determination of DNA revealed that ascorbic acid, as well as SBA, induced DNA fragmentation into nucleosomal oligomers in human myelogenous leukemic cell lines, but not in freshly isolated human peripheral blood cells. The results suggest that antitumor activity of SBA might be at least in part mediated by the action of ascorbic acid, a degradation product of SBA.

Animals↗
PubMedDate not supplied

Induction of DNA fragmentation by tannin- and lignin-related substances.

A variety of tannin and lignin-related compounds were compared for their ability to induce nucleosome-sized DNA fragmentation (a biochemical hallmark of apoptosis), using agarose gel electrophoresis and a fluorescence activated cell sorter. Monomeric, dimeric, trimeric and tetrameric hydrolysable tannins induced nucleosome-sized DNA fragmentation in HL-60 cells, more potently than condensed tannins. The highest activity was detected in gallic acid, a component unit of tannins. Natural lignified materials, except for caffeic acid and its dehydrogenation polymer, showed much weaker activity. Protein-bound polysaccharide (PSK) was inactive. Gallic acid induced DNA fragmentation in four human myelogenous leukaemic cell lines, but not in human T-cell leukaemia and erythroleukaemia cell lines. Ca2+ depletion from the culture medium slightly, but significantly, reduced the apoptosis-inducing activity of gallic acid, but did not significantly affect that of tannic acid or caffeic acid. After treatment with gallic acid, intracellular Ca2+ concentration was significantly elevated. The apoptosis-inducing activity of polyphenols may further emphasize their medicinal efficacy.

Apoptosis↗
PubMedDate not supplied

Relationship between ascorbyl radical intensity and apoptosis-inducing activity.

Ascorbic acid and its related compounds were compared for their ascorbyl radical intensity and apoptosis-inducing activity. Sodium L-ascorbate, L-ascorbic acid, D-isoascorbic acid, sodium 6-beta-O-galactosyl-L-ascorbate and sodium 5,6-benzylidene-L-ascorbate, at the concentration of 1-10 mM, induced apoptotic cell death characterized by cell shrinkage, nuclear fragmentation and internucleosomal DNA cleavage in human promyelocytic leukemic HL-60 cells. On the other hand, L-ascorbic acid-2-phosphate magnesium salt and L-ascorbic acid 2-sulfate did not induce any of these apoptosis-associated characteristics. ESR measurements revealed that all the active compounds were progressively degraded, producing the ascorbyl radical (g = 2.0064, hfc = 0.17 mT) in culture medium, whereas the inactive compounds were stable and did not produce the ascorbyl radical. Cytotoxicity began to appear when the radical intensity exceeded a certain threshold level. In the presence of N-acetyl-L-cysteine, both ascorbyl radical intensity and apoptosis-inducing activity were significantly reduced. These data suggest the possible involvement of the ascorbyl radical in apoptosis induction by ascorbic acid-related compounds. Exposure of HL-60 cells to ascorbic acid or its active derivatives resulted in the rapid elevation of intracellular Ca2+ concentration, which might serve as the initial signal leading to the cell death pathway.

Antineoplastic Agents↗