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Biomedical subjects

T Oi

Publications and source records attributed to T Oi.

26 records · Page 2Linked to original sources
PubMedDate not supplied

Biological information processing requires quantum logic.

Chaos dynamics, which characterizes biological information processing, generates information along the course of temporal development of the relevant system. In this system, the macroscopic uncertainty principle holds between observation time delta t and phase space volume delta omega determined by this observation. In other words delta t and delta omega cannot simultaneously be small. This principle corresponds to the microscopic uncertainty principle that holds in quantum physics. Through an analogy to this correspondence, it is shown that quantum logic might also govern such macroscopic phenomena as are governed by chaos dynamics.

Behavior↗
PubMedDate not supplied

Prevention of oral diseases by polyphenols (review).

This review summarizes the current data on the effects of natural products on various oral diseases, together with their basic biological activities. We have focused on polyphenols and their secondary metabolites, such as tannins, lignins and flavonoids, and their modulating factors, including saliva proline-rich proteins. These substances are found in a wide variety of plant sources such as vegetables, herbs, nuts and teas, and effectively reduce the incidence of carcinogenesis in the oral cavity, inhibit plaque growth and adsorption of oral bacteria, and inhibit the replication of various viruses. The mechanism of their action includes: the direct inactivation of the bacteria and viruses, inhibition of their replication enzymes, induction of apoptosis in tumor cells, stimulation of monocytes/macrophages to produce cytokines, and stimulation of myeloperoxidase-dependent iodination of neutrophiles. Polyphenols showed biphasic actions, acting as antioxidants at lower doses, but acting as prooxidants at higher doses. The development and progression of oral diseases might be modified not only by these natural products, but also by interaction with saliva, proline-rich proteins, antioxidants, metals and dental materials.

Animals↗
PubMedDate not supplied

Interaction between sodium 5,6-benzylidene-L-ascorbate and gallic acid.

The interaction between sodium 5,6-benzylidene-L-ascorbate (SBA) and gallic acid was investigated by two different parameters: radical intensity and cytotoxicity induction. These compounds produced ESR signals of radicals under alkaline conditions. The addition of increasing concentrations of SBA completely scavenged the gallate radical and replaced the latter with its ascorbate radical. On the other hand, gallic acid dose-dependently enhanced the radical intensity of SBA. Both of these two compounds dose-dependently reduced the viable cell number of human squamous carcinoma HSC-2 cells without inducing internucleosomal DNA cleavage. Electron micrographs of the dying cells demonstrate the irreversible degenerative changes especially in the cytoplasm of the cells. The cytotoxic activity of gallic acid was almost completely eliminated by catalase, whereas SBA was totally insensitive to catalase. When these two compounds were mixed together before adding to HSC-2 cells, the cytotoxic activity of gallic acid was significantly reduced by SBA, whereas that of SBA was not reduced by gallic acid. SBA dose-dependently reduced the gallate oxidation in the culture medium. The interaction between SBA and gallic acid may modify their individual biological activity.

Antineoplastic Agents↗
PubMedDate not supplied

Role of carbohydrate moiety in granulocyte colony stimulating factor.

Biological activities of two granulocyte-colony stimulating factor (G-CSF) preparations with (Lenograstim) or without (Filgrastim) sugar moiety were compared. Both G-CSF preparations similarly enhanced the N-Formyl-Met-Leu-Phe-induced-migration of human peripheral blood polymorphonuclear cells, but did not significantly affect the proliferation of human oral tumor cell lines (HSC-2, HSG). However, Lenograstim induced cytotoxicity (accompanied by the production of cytoplasmic vacuoles and large DNA fragments) in human promyelocytic leukemic cells HL-60, more potently than Filgrastim. Lenograstim, but not Filgrastim, enhanced the cytotoxic activity of sodium ascorbate. In contrast to Lenograstim, Filgrastim was degraded gradually, but too slowly to explain its lower biological activity. These data suggest that the carbohydrate moiety in G-CSF might confer unique biological activities.

Ascorbic Acid↗
PubMedDate not supplied

Role of hydrogen peroxide in antitumor activity induction by sodium 5,6-benzylidene-L-ascorbate.

Role of hydrogen peroxide (H2O2) in the induction of antitumor activity against chemically-induced rat hepatocellular carcinoma by sodium 5,6-benzylidene-L-ascorbate (SBA) was investigated. ESR spectroscopy demonstrated that rat liver homogenate of cancerous tissue significantly enhanced the radical intensity of SBA more potently than that of precancerous or normal tissue. The peroxyoxalate chemiluminescence method demonstrated that SBA significantly enhanced the production of H2O2-derived chemiluminescence intensity in the liver homogenates, and the effect of SBA was greater in cancerous tissue than in precancerous or normal tissue. Addition of ascorbic acid, a degradation product of SBA, showed similar but slightly weaker stimulation effects. These data suggest that antitumor activity of SBA in vivo might, at least in part, be due to H2O2 production.

Animals↗