Biomedical subjects

M Ohta

Publications and source records attributed to M Ohta.

At least 1,153 records · Page 64Linked to original sources

PubMed1984

Ultrastructure of Klebsiella O3 lipopolysaccharide isolated from culture supernatant: comparison with other lipopolysaccharides.

Klebsiella O3 lipopolysaccharide (KO3 LPS) isolated from the culture supernatant, which was found to exhibit a very strong adjuvant activity in augmenting antibody response and delayed-type hypersensitivity to protein antigens in mice, was examined by electron microscopy. When negatively stained with uranyl acetate or ammonium molybdate, the KO3 LPS was found to consist principally of flat ribbon-like structures branching freely (average width 16 nm and average thickness 7 nm) and to contain a small proportion of spheres (diameter 20-50 nm), both structures covered with fine hairy structures (average length approximately 10 nm). When the polysaccharide of KO3 LPS was stained by the periodic acid-thiosemicarbazide-silver proteinate procedure, silver granules were deposited on the ribbon-like structures and around the spheres, suggesting that the polysaccharide moiety is located on their surface and that the fine hairy structures consist of the polysaccharide moiety. Comparison by means of preparations stained with uranyl acetate or ammonium molybdate showed that KO3 LPS isolated from the culture supernatant has structural features in common with KO3 LPS isolated from bacterial cells, Escherichia coli O9 LPS isolated from the culture supernatant, and E. coli O127 LPS isolated from bacterial cells. On the basis of the present results, schematic representations of the common physical structure of LPS were drawn; the fine hairy structures attach to the wide surface of the flat ribbon-like structures along their lateral margin.

Escherichia coli↗

PubMed1984

Ultrastructure of Klebsiella O3 lipopolysaccharide isolated from culture supernatant: structure of various uniform salt forms.

Various uniform salt forms of Klebsiella O3 lipopolysaccharide (KO3 LPS) isolated from culture supernatant were prepared as follows. Basic materials present in KO3 LPS were rigorously removed by electrodialysis and the electrodialyzed KO3 LPS was neutralized with NaOH, KOH, NH4OH, Ca(OH)2, tris(hydroxymethyl)aminomethane, or triethylamine. The ultrastructure of the uniform salt forms of KO3 LPS was examined using preparations stained with uranyl acetate. The sodium, potassium, ammonium, and trisaminomethane salt forms were structurally very similar to the natural form of KO3 LPS which consisted of a mixture of flat ribbon-like structures (average width of 16 nm and average thickness of 7 nm) and spheres with various diameters, both covered with fine hairy structures. When KO3 LPS was converted to the triethylamine salt form, the ribbon-like structures were disrupted into very small granules (7-9 nm X 9-15 nm). The calcium salt form consisted of particles and rods of various sizes and ribbon-like structures which were markedly extended (maximum width of 50 nm) and presented irregular shapes. When converted to the calcium salt form, the ribbon-like structures were extended and eventually divided into particles and rods. For reasons still unknown, the sodium salt of KO3 LPS was mostly stained positively with uranyl acetate in contrast to the natural form and the other uniform salt forms which were always negatively stained. In the positively stained preparation of the sodium salt form, it was clearly shown that the ribbon-like structures consisted of a bilayer.

Klebsiella↗

PubMed1984

Adjuvant activity of Klebsiella O3 lipopolysaccharide: comparative study using defined uniform salt forms.

Previously we showed that Klebsiella O3 lipopolysaccharide (KO3 LPS) is much more potent than other kinds of LPS including Escherichia coli O127 LPS (EO127 LPS) in adjuvant activity in augmenting antibody response and delayed-type hypersensitivity to protein antigens and in the ability to enlarge the regional lymph node. Various defined uniform salt forms, the triethylamine, sodium, potassium, ammonium, tris(hydroxymethyl)aminomethane, and calcium salt forms, of KO3 LPS and EO127 LPS were prepared by removing basic materials present in LPS preparations by electrodialysis and neutralizing the electrodialyzed LPS preparations with various kinds of alkali. The triethylamine salt form showed the best solubility and consisted of the smallest granules and, on the other hand, the calcium salt form showed the lowest solubility, compared with the natural form and the other uniform salt forms. Even if the natural forms of KO3 LPS and EO127 LPS were converted to the defined uniform salt forms, adjuvanticity of KO3 LPS and EO127 LPS in augmenting delayed-type hypersensitivity to ovalbumin and the ability to enlarge the regional lymph node did not significantly differ from those of the respective natural forms. From these results it is concluded that the difference in strength of the adjuvanticity between KO3 LPS and EO127 LPS is not due to the difference in their salt forms, solubility or physical state. Moreover, there were no significant differences in lethal toxicity for mice by the intraperitoneal route among the natural form and all the uniform salt forms of KO3 LPS tested.

Adjuvants, Immunologic↗

PubMed1984

Phorbol myristate acetate-induced modulation of antibody-dependent cellular cytotoxicity by human polymorphonuclear leukocytes.

The effect of phorbol myristate acetate (PMA) on the antibody-dependent cellular cytotoxicity (ADCC) of human polymorphonuclear leukocytes (PMNs) against human erythroleukemic K562 cells was studied by the use of a 3-h 51Cr-release assay. Pretreatment of PMNs with PMA (10 ng/ml) for 60 min resulted in inhibition of subsequent ADCC. This inhibition was dependent on doses of PMA. The effect of pretreatment of PMNs with PMA on O2- generation of the cells was also studied. The ability of the cells to generate O2- was not suppressed, and the expression of Fc receptors on the cell membrane was well preserved. In contrast, the addition of PMA to the ongoing ADCC (5 to 30 min after the start of the ADCC assay) enhanced the activity of the cells for ADCC. This augmentation was abolished by catalase, whereas ADCC itself was not affected by the agent. These results imply divalent effects of PMA on the ADCC of PMNs. The suppression of ADCC activity of PMNs by pretreatment with PMA is not due to inhibition of the reactive oxygen burst of the cells. The augmentation of ongoing ADCC by the addition of PMA is due to secretion of hydrogen peroxide from the cells induced by PMA, and this augmentation occurs only when the interaction between effector and target cells exists through Fc receptor.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1984

Functional maturation of membrane potential changes and superoxide-producing capacity during differentiation of human granulocytes.

The alterations of stimulus-induced membrane potential changes, superoxide (O2-)-producing capacity and phagocytic activity during differentiation of human granulocytes were investigated in the human leukemia cell lines HL-60 and KG-1 differentiating in vitro and in human leukemic granulocytes obtained from chronic myelogenous leukemia patients. HL-60 cells incubated with dimethyl sulfoxide or with retinoic acid showed progressively increasing O2- production as well as membrane potential changes (depolarization) on contact with phorbol myristate acetate or the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine, with a concomitant increase in the proportion of mature cells of the granulocytic type. Phagocytosis of latex particles, yeast, and oil droplets appeared 24 h after incubation with dimethyl sulfoxide and anteceded the increment of O2- production and membrane potential changes, both of which appeared concomitantly 3 d after incubation with dimethyl sulfoxide. Similar findings were observed when immature and mature granulocytes obtained from chronic myelogenous leukemia patients were stimulated by phorbol ester, the chemotactic peptide, or calcium ionophore A23187, and the amount of O2- production was parallel to the magnitude of membrane potential changes. HL-60 and KG-1 cells incubated for 1-6 d with phorbol myristate acetate showed neither O2- production nor membrane potential changes on contact with phorbol ester, chemotactic peptide, or A23187, although such cells resembled macrophages morphologically, and their phagocytic activity was significantly increased. O2- production and membrane potential changes in normal granulocytes induced by phorbol ester, chemotactic peptide and A23187 were inhibited by 2-deoxyglucose. These findings indicate that the O2--producing system and the system provoking membrane potential changes may develop concomitantly as human granulocytes mature and differentiate, and that the development of these systems and of phagocytic activity may be independently regulated.

Adult↗

PubMed1984

Necrotic changes in prolactinomas after long term administration of bromocriptine.

Six prolactinoma patients were studied endocrinologically and their tumors were examined histologically after long term bromocriptine therapy. In patient 1 with a large prolactinoma, a marked reduction in size and a remarkable decrease in elevated serum PRL levels occurred after bromocriptine treatment for 8 months. The histological findings consisted of two components, i.e. shrunken island-like cell nests and acellular spaces. Some degenerative and necrotic tumor cells, hyaline substance, and fibrosis were observed with light and electron microscopy in these acellular spaces. Island-like cell nests consisted of atrophic cells having disproportionally scanty cytoplasm. The same histological findings were observed in four other patients. However, in another patient whose tumor decreased in size only slightly during bromocriptine therapy, the specimen had few acellular spaces. Thus, long term bromocriptine treatment of patients with prolactinomas may result in necrosis of some adenoma cells in some patients.

Adolescent↗

PubMed1984