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Biomedical subjects

T Namba

Publications and source records attributed to T Namba.

At least 217 records · Page 12Linked to original sources
PubMed1989

Screening of Taiwanese crude drugs for antibacterial activity against Streptococcus mutans.

Preliminary antibacterial screening of local crude drugs was carried out using the cariogenic bacterium, Streptococcus mutans. Of 79 aqueous extracts tested, 6 crude drugs were shown to have significant antibacterial activity with minimal inhibitory concentration equal to or lower than 7.8 mg/ml (expressed in terms of dry starting material). Of these effective crude drugs, Morus australis, Ludwigia octovalvis and Thuja orientalis were very effective in inhibiting the growth of serotypes c and d of S. mutans (MIC less than or equal to 2.0-7.8 mg/ml). Elephantopus scaber, Artemisia vulgaris, Mosla chinensis and Orthosiphon aristatus also exhibited considerable antibacterial activity (MIC = 7.8-23.4 mg/ml) against both serotypes. In the presence of 5% sucrose, the antibacterial potency of the majority of the extracts did not change for type c, while the potency decreased about one-half for type d.

Anti-Bacterial Agents↗
PubMed1989

Biochemical changes related to aging in the senescence-accelerated mouse.

Several biochemical parameters reflecting the degree of senescence were compared between senile-prone (P) and resistant (R) strains of male senescence-accelerated mouse (SAM) at 11 to 12 months of age. Plasma testosterone in SAM-P amounted to half the concentration in SAM-R. In the liver and brain of SAM-P, the content of malondialdehyde (MDA) and the activity of monoamine oxidase B (MAO-B) were significantly higher than those in SAM-R. Moreover, large amounts of fluorescent lipofuscin were detected in the SAM-P liver. Compared with SAM-R, both membrane and cytosolic fractions from the SAM-P liver contained small amounts of protein and showed less activity of superoxide dismutase (SOD). The present findings suggest that the male SAM-P rapidly acquires biochemical changes which are considered to be part of the normal aging process.

Aging↗
PubMed1989

Metabolism of swertiamarin from Swertia japonica by human intestinal bacteria.

The biotransformation of swertiamarin [1, a seco-iridoid glucoside isolated from Swertia japonica (Schult.) Makino] by human intestinal bacteria was investigated. Three metabolites were isolated and identified as erythrocentaurin (2), 5-hydroxymethylisochroman-1-one (3), and gentianine (4) by spectroscopic methods. Through screening of various defined strains of intestinal bacteria (25 species), it was found that all these species had the ability to metabolize 1 to 2 and 3, whereas only a few species had the ability to produce 4. This is the first report to show that one of the metabolic intermediates of the secoiridoid compound is further transformed to a nitrogen-containing compound through metabolic processes by human intestinal bacteria.

Feces↗
PubMed1989

Metabolism of gentiopicroside (gentiopicrin) by human intestinal bacteria.

As a part of our studies on the metabolism of crude drug components by intestinal bacteria, gentiopicroside (a secoiridoid glucoside isolated from Gentiana lutea), was anaerobically incubated with various defined strains of human intestinal bacteria. Many species had ability to transform it to a series of metabolites. Among them, Veillonella parvula ss parvula produced five metabolites, which were identified as erythrocentaurin, gentiopicral, 5-hydroxymethylisochroman-1-one,5-hydroxymethylisochromen-1- one and trans-5,6-dihydro-5-hydroxymethyl-6-methyl-1H,3H-pyrano[3,4-c]pyra n-1-one.

Bacteria↗
PubMed1989

Pharmacological study of a traditional Chinese medicine: effect of bezoar bovis on the irregular beating pattern of cultured mouse myocardial cells.

The water-extract from "Bezoar bovis", a drug used in Chinese traditional medicine, was examined for its ability to alter the beating pattern of spontaneously contracting cultured embryonic mouse myocardial cells following changes in extracellular calcium (Ca2+). Incubation of the cells with medium containing low Ca2+ concentration (0.4 mM) caused the number of beating cells and beating rate to decrease and the number of arrhythmic cells to increase. By contrast, the number of beating cells decreased while beating rate and the number of arrhythmic cells increased at high Ca2+ (20 mM). Addition of Bezoar bovis extract to the medium attenuated the response to varying Ca2+ concentration. One of the major constituents of Bezoar bovis extract, taurine, was effective in protecting against the abnormal beating pattern induced by high Ca2+. Since beta-alanine, an inhibitor of taurine transport, antagonized the protective effects of both Bezoar bovis and taurine, it is likely that the effect of Bezoar bovis is partially mediated by taurine.

Alanine↗
PubMed1989

[Chronic toxicity of tobacco smoke on the visual system].

The chronic toxicity of tobacco smoke on the rats visual system was studied. Six male Wistar rats had been subjected to five hour's daily passive smoking of 15 cigarettes for 52 weeks, in an attempt to produce tobacco amblyopia. Elongation of the peak latency time of N1 and P1 waves in the visual evoked potential (VEP) was recognized. Histopathologically, some degree of glial proliferation and pyknosis was observed in the optic nerves of all treated rats, and massive disappearance of nerve fibers was seen in one severely affected case. Electron microscopic examination proved that unmyelinated nerve fibers increased in number and the myelin sheath was thinner than that of the untreated control rats, while axons were relatively well preserved. The distribution in the magnitude of the axon diameter histogram was shifted towards a smaller diameter than that of the control rats. Electroretinography (ERG) did not show any significant changes of the latency and the amplitude of both a- and b- waves, and no histopathological changes were seen in the sensory retina. Neither functional nor histological changes were seen in the sciatic nerves. These results indicated that the optic nerve is thought to be more vulnerable to tobacco smoke than the peripheral nerves and we consider that a primary change of the nerve is demyelination at the retrobulbar portion of the optic nerve.

Animals↗
PubMed1988

Insect-derived crude drugs in the Chinese Song dynasty.

Fifty-four kinds of crude drug derived from insects are listed in the "herbal" Jing-shi-zheng-lei-da-guang-ben-cao (1108 A.D.) edited during the Chinese Song dynasty (960-1280 A.D.). We considered each of them from the viewpoint of various herbals and have commented on them, the order being adhered to in most cases. We added our own findings of identification of insect crude drugs available on the market. The crude drugs emphasized are mantis egg case, wasp's nest, scarab larva, red cicada, snipe fly, horse fly, flying cockroach, Eupolyphaga, Chinese Cantharides and scarab beetle. Others are discussed to a lesser extent.

Animals↗
PubMed1988

Superoxide dismutase-mediated reversible conversion of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole, the N-hydroxy derivative of Trp-P-2, into its nitroso derivative.

Aerobic oxidation of 3-hydroxyamino-1-methyl-5H-pyrido-[4,3-b]indole [Trp-P-2(NHOH)] in neutral aqueous solution was greatly accelerated by copper-zinc superoxide dismutase (SOD). The major product in this SOD-mediated reaction was identified as 3-nitroso-1-methyl-5H-pyrido[4,3-b]indole [Trp-P-2(NO)]. This conversion was accompanied by a decrease of the mutagenicity of the mixture, as monitored by the direct-acting mutagenicity on Salmonella typhimurium TA98; a rapid change to approximately 1/3 of the original mutagenicity was followed by no further decrease of the activity. In contrast, in the spontaneous aerobic oxidation of Trp-P-2-(NHOH), the mutagenicity slowly and continuously decreased, until it was finally lost almost completely. Similar acceleration by SOD of aerobic oxidation was found for 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole [Glu-P-1(NHOH)]. Again, mutagenicity of approximately 1/4 that of the original was retained in the SOD-mediated decomposition, while a complete loss of the mutagenicity was observed in the spontaneous decomposition. When Trp-P-2(NO) was treated with the superoxide-generating system, xanthine oxidase plus xanthine, Trp-P-2(NHOH) was formed. Therefore, the role of SOD in the conversion of Trp-P-2(NHOH) into Trp-P-2(NO) is the removal of superoxide anions generated by reduction of aerobic oxygen, thereby inhibiting the reverse reactions, i.e. the reduction of Trp-P-2(NO) and that of the putative intermediate nitroxide radical. In support of this proposed mechanism, phenylhydroxylamine underwent a SOD-accelerated conversion to nitrosobenzene, and nitrosobenzene was reduced to phenylhydroxylamine by the action of the xanthine oxidase-xanthine system. Hence, this reversible interchange between an arylhydroxylamine and its nitroso compound, coupled with the oxygen-superoxide cycle, may be a general phenomenon. A consequence of this finding is that the xenobiotic N-hydroxylamines may be converted by the action of SOD in the biological settings into nitroso compounds, which are chemically more stable, serving as a reservoir for mutagenicity.

Carbolines↗
PubMed1988

Purification and properties of 3 alpha-hydroxyglycyrrhetinate dehydrogenase of Clostridium innocuum from human intestine.

3 alpha-Hydroxyglycyrrhetinate dehydrogenase of Clostridium innocuum, isolated from human intestinal bacteria, was capable of converting 3-ketoglycyrrhetic acid to 3 alpha-hydroxyglycyrrhetic acid. The enzyme was purified to homogeneity by means of butyl-Toyopearl 650M, Sephadex G-150, Matrex Red A, Toyopearl HW-55S, and isoelectric focusing column chromatographies. The purified enzyme showed a specific activity of 156 mumol/min.mg toward 3 alpha-hydroxyglycyrrhetic acid, and showed a single band on SDS-polyacrylamide gel electrophoresis. The apparent molecular weight was 53,000, as estimated by gel filtration, and 30,000, as judged by SDS-polyacrylamide gel electrophoresis. Its isoelectric point was 5.2. The enzyme showed absolute specificity for the 3 alpha-hydroxyl and 3-ketonic groups of 18 alpha- or 18 beta-glycyrrhetic acid and required NADP+ and NADPH as cosubstrates. The enzyme did not act on any 3 alpha-hydroxyl or 3-ketonic group of steroids or bile acids. The enzyme is a novel type of enzyme, defined as 3 alpha-hydroxy-glycyrrhetinate dehydrogenase, being quite different from 3 alpha-hydroxysteroid dehydrogenase [EC 1.1.1.50].

3-Hydroxysteroid Dehydrogenases↗
PubMed1988

Metabolism of sennosides by human intestinal bacteria.

During the course of studies on the metabolism of sennosides by human intestinal bacteria, an enzyme which takes part in the reduction of sennosides and sennidins was originally isolated from Peptostreptococcus intermedius. This enzyme catalyzed the electron transfer from NADH to FAD, FMN or benzyl viologen, which reduced nonenzymatically sennosides and sennidins to 8-glucosyl-rhein anthrone and rhein anthrone, respectively.

Anthraquinones↗