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Biomedical subjects

I Yano

Publications and source records attributed to I Yano.

At least 181 records · Page 10Linked to original sources
PubMed1980

ESR studies on the membrane properties of a moderately halophilic bacterium. II. Effect of extreme growth conditions on liposome properties.

Lipid preparations from the cells of a moderately halophilic bacterium, Pseudomonas halosaccharolytica grown under the two extreme conditions of high temperature-high NaCl concentration and low temperature-low NaCl concentration showed distinctively different profiles in phospholipid and fatty acid composition. Cells grown at 40 degrees C in medium containing 3.5 M NaCl had high concentrations of saturated and C19 cyclopropanoic fatty acids (about 50 per cent of the total), whereas cells grown at 20 degrees C in medium containing 0.5 M NaCl had decreased concentrations of these fatty acids with increased concentrations of the corresponding unsaturated fatty acids. The phospholipid composition was also affected ty the culture conditions; cells grown at 40 degrees C in 3.5 M NaCl had large amounts of acidic phospholipids, whereas those grown at 20 degrees C in 0.5 M NaCl had small amounts. ESR studies on liposomes prepared from lipids of cells grown under the two conditions showed characteristic profiles for correlation times and order parameters of three spin labels of stearic acid derivatives similar to those of membranes of whole cells of this bacterium. ESR studies showed that the physical properties of the liposomes from the total extractable lipids and isolated phosphatidylglycerol from the cells were completely different from those of synthetic dioleoylphosphatidylglycerol. Liposomes of the lipids extracted from cells grown at 40 degrees C in 3.5 M NaCl showed change in rotational viscosity on altering the NaCl concentration to 0.5M, whereas liposomes of lipids extracted from cells grown at 20 degrees C in 0.5 M NaCl did not show change in rotational viscosity on increasing the NaCl concentration to 3.5 M.

Electron Spin Resonance Spectroscopy↗
PubMed1980

Comparative studies on the hepatotoxic actions of chloroform and related halogenomethanes in normal and phenobarbital-pretreated animals.

Hepatotoxic action of CHCl3 was examined biochemically by comparing with those of CCl4 and other related halogenomethanes using normal and phenobarbital (PB)-pretreated animals. In the later stage (24 hr), in mice, PB pretreatment augmented CHCl3-induced liver damage as evidenced by an enhancement of elevation of plasma transaminase activities and a parallel rise in liver triglyceride content. In the earlier stage (1 hr), in normal rats, CCl4 (1.0 ml/kg, i.p.) decreased microsomal glucose-6-phosphatase (G-6-Pase) activity and cytochrome P-450 content, whereas no significant effect was observed with the same dose of CHCl3. PB pretreatment produced a significant loss of both enzymes by CHCl3, and enhanced the loss of cytochrome P-450 induced by CCl4, while G-6-Pase activity was little affected by CCl4 in PB-pretreated rats. Both hepatotoxins increased liver malondialdehyde (MDA) content. Some of these early changes in vivo were reproduced in the lipid peroxidation system in vitro. Diethyldithiocarbamate suppressed various toxic manifestations induced by CHCl3 in PB-pretreated rats, but did not protect against the loss of cytochrome P-450 induced by CHCl3 or CCl4. These results suggest that lipid peroxidation hypothesis proposed for CCl4 hepatotoxicity may be applied to the case of CHCl3 though there exist some qualitatively different characteristics between these hepatotoxins, and that the mechanisms of the loss of microsomal G-6-Pase and cytochrome P-450 by either of these hepatotoxins might be different.

Animals↗
PubMed1980

Regulation of cell wall mycolic acid biosynthesis in acid-fast bacteria. I. Temperature-induced changes in mycolic acid molecular species and related compounds in Mycobacterium phlei.

Molecular species of two major subclasses of mycolic acids from Mycobacterium phlei, alpha-mycolic acids (M1) and dicarboxy mycolic acids (M3), were separated gas-chromatographically and identified mass-spectrometrically. The mycolic acid compositions of extractable and cell wall bound lipids were markedly influenced by growth temperature. Increasing growth temperature from 20 degrees C to 50 degrees C resulted in an increase in longer chain species of both mycolisc acid subclasses with a concomitant decrease in shorter chain homologues. The most abundant molecular species were C76 and C58 of M1 and M3 in the 20 degrees C grown cells, while the 50 degrees C grown cells contained C80 in M1 and C62 in M3, most abundantly. Changes in mycolic acid composition occurred rapidly after growth temperature was raised from 20 degrees C to 50 degrees C with an increase in C62 and a concomitant decrease in C58. Mass fragmentographic analysis revealed that an increase in total carbon numbers of mycolic acids was caused by the elongation of straight chain alkyl unit, without any changes in alpha-branch. Changes in the molecular species composition of secondary alcohols presumably derived from the ester mycolic acids were also observed and an increase in longer species (C20-ol-2) with a concomitant decrease in shorter ones (C18-ol-2) was noted as the temperature rose. An increase in the growth temperature also resulted in a decrease in unsaturated fatty acids in extractable lipids. These observations suggest that mycobacteria alter the molecular species composition of mycolic acid subclasses and phospholipids, in response to growth temperature, to maintain a suitable membrane function.

Cell Wall↗
PubMed1980

Mitogenic effects of bacterial cell walls and their components on murine splenocytes.

Stimulation of splenocytes from ICR mice by cell walls of 17 species of gram-positive bacteria, and peptidoglycans and water-soluble enzymatic digests prepared from some of them, and by synthetic N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) was studied in terms of mitogenic activity. All the cell walls tested except those of Micrococcus lysodeikticus, regardless of their mycolic acid content and immunopotentiating activity, had definite stimulatory activity on splenocytes. In general, the cell walls of mycobacteria, nocardia, and stretomyces had stronger mitogenic activity than other cell walls. The mitogenic activity of cell walls was mainly attributable to a peptidoglycan moiety, and the activity was retained even when the peptidoglycan had been degraded into a monomer or a dimer of its subunit, though a polymerized form of the subunits exhibited stronger activity than the monomer or dimer. Definite mitogenicity of synthetic MDP on splenocytes from ICR mice was also confirmed. The origin of the unknown principle(s) that is found in the cell walls of nocardia, mycobacteria and streptomyces and is responsible for their potent mitogenic activity on murine splenocytes was discussed.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Enhanced naloxone potency and the development of narcotic tolerance.

When various biogenic amine modifying drugs were administered to mice which were pretreated with morphine, none of the drugs except atropine and haloperidol altered the usual doubling of the naloxone efficacy which is observed in morphine-pretreated mice. Atropine appeared to decrease the potency of naloxone. Haloperidol, which did not alter naloxone potency in normal mice, further increased the naloxone potency in morphine-pretreated mice. When the biogenic amine modifiers were injected chronically to mice during the development of morphine tolerance, again none of the drugs, except haloperidol and atropine altered the development of tolerance. Haloperidol appeared to enhance and atropine to inhibit the degree of tolerance. These results indicate that it is the alteration in the narcotic-induced enhancement of naloxone potency and not the mere alteration of noloxone potency by various drugs, which can be used as an indicator of the alterations in the development of tolerance.

Animals↗
PubMed1979

Occurrence of free ceramides in Bacteroides fragilis NCTC 9343.

The occurrence of free ceramides at high concentrations was demonstrated in the chloroform-methanol extractable lipids of Bacteroides fragilis NCTC 9343. The long-chain bases were isolated from the free ceramides and identified as branched and normal saturated dihydroxy bases with carbon chains consisting of 17, 18, and 19 atoms. The major fatty acid was 3-hydroxy 15-methylhexadecanoic acid. The major molecular species of the ceramides were identified by gas chromatography-mass spectrometry and gas chromatography of the cleaved products as LCB-d-iso17: 0-3-OH iso17: 0 FA, LCB-d-anteiso17: 0-3-OH iso17: 0 FA, LCB-d-iso18: 0-3-OH iso17: 0 FA, and LCB-d-anteiso19: 0-3-OH iso17: 0 FA.

Bacteroides fragilis↗
PubMed1979

Macrophage activation by bacterial cell walls and related synthetic compounds.

Activation of peritoneal macrophages from guinea pigs by various bacterial cell walls, M-1 endo-N-acetylmuramidase enzymatically digested bacterial cell walls and synthetic muramyl dipeptides was studied in terms of stimulation of [14C] glucosamine incorporation. All test bacterial cell wall preparations significantly increased a [14C]glucosamine uptake by the macrophages. Some of the water-soluble M-1 enzyme digests also exerted stimulating effects on macrophages, although the activity of the digests was found to be weaker than those of original cell walls. Furthermore, an adjuvant-active synthetic MurNAc-L-Ala-D-isoGln (MDP) showed a weak but significant activity, whereas an adjuvant-inactive analog, MurNAc-L-Ala-L-iso-Gln, did not show a significant activity, at least with the dose of 100 microgram. Additional studies with 6-O-acyl derivatives of MDP revealed that 6-O-(2-tetradecylhexadecanoyl)-MDP and 6-O-(3-hydroxy-2-tetradecyl-octadecanoyl)-MDP exhibit stronger macrophage-stimulating effects than MDP. It can be concluded from the above findings that MDP is the essential structure responsible for stimulating the activity of cell walls on guinea pig peritoneal macrophages, but it requires a particle state, which results from an additive character of lipophilicity, to exert the activity fully and effectively.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Mitogenic effects of bacterial cell walls, their fragments, and related synthetic compounds on thymocytes and splenocytes of guinea pigs.

Stimulation of [(3)H]thymidine incorporation of thymocytes and splenocytes from guinea pigs by various bacterial cell walls and their peptidoglycans, by enzymatic digests, and by synthetic muramyl dipeptides was studied as an indication of mitogenic activity. Cell wall and peptidoglycan preparations, isolated from 19 strains belonging to 18 different species, definitely increased [(3)H]thymidine incorporation of thymocytes as well as splenocytes, regardless of mycolic acid contents as a non-peptidoglycan component. Both the cell walls from Nocardia corynebacteriodes (containing mycolic acids) and those from Streptomyces gardneri (lacking mycolic acids) showed far stronger mitogenic activities on splenocytes than other cell walls (stimulation index, 25 to 30). Furthermore, water-soluble enzymatic digests, notably the endopeptidase digests, which generally were greater in degree of polymerization of peptidoglycan subunits than the glycosidase digests obtained from representative cell walls, were found to have as distinct a stimulating activity on splenocytes as the original cell walls. In contrast, solubilization of the cell walls by enzymes, irrespective of endopeptidases or glycosidases, was accompanied by disappearance of the mitogenic activity on thymocytes. On the other hand, studies with synthetic 6-O-acyl-MurNAc-l-Ala-d-isoGln preparations (6-O-acyl-MDPs) revealed that 6-O-stearoyl-MDP and 6-O-(2-tetradecylhexadecanoyl)-MDP, unlike MDP, had distinct mitogenic activity on thymocytes, whereas their activity on splenocytes was rather weaker than MDP itself. The findings presented here suggest that MDP is the minimal structure for the mitogenic activities of bacterial cell walls on guinea pig splenocytes, but that MDP, though distinctively active by itself, requires a polymerized form to exert effectively its inherent stimulating activities on splenocytes. On the other hand, on thymocytes, MDP, unless it takes a particular form or has appropriate additive groups, cannot exert its mitogenic activities.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Antagonism by naloxone of tolerance and dependence in mice given a single dose of morphine.

The effect of naloxone given at various times after morphine administration on the development of tolerance to and dependence on a single dose of morphine was studied. Naloxone antagonized the analgesic effect of morphine and the development of tolerance to and dependence on morphine, dose dependently. The time course of the development of tolerance to a single dose of morphine almost paralleled that of dependence on morphine but the time course of the disappearance of tolerance did not coincide with that of dependence. When start of the duration of action of morphine was blocked by naloxone for various time intervals, the degree of tolerance to and dependence on morphine was antagonized, time dependently. When the end of the duration of action of morphine was antagonized by naloxone for various time intervals, tolerance and dependence which developed up to that time was completely antagonized by naloxone.

Analgesics↗
PubMed1978

Isolation of a novel sphingoglycolipid containing glucuronic acid and 2-hydroxy fatty acid from Flavobacterium devorans ATCC 10829.

A new acidic sphingoglycolipid has been isolated from a Gram-negative, glucose-non-fermentative (obligatory aerobic) bacterium, Flavobacterium devorans ATCC 10829, by thin-layer chromatography on silica gel after mild alkaline hydrolysis of the cellular lipids. Chemical degradation studies, thin-layer chromatographic behavior, IR and mass-spectrometric analysis of the original and reduced glycolipid with LiA1H4 revealed that the lipid contained glucuronic acid, long-chain bases, and fatty acids in a molar ratio of approximately 1:1:1. The major long-chain bases were identified by gas chromatography-mass spectrometry as dihydrosphingosine (d-18 :0) and longer homologues, while the N-acyl group was exclusively 2-hydroxy myristic acid. The most probable structure of this glycolipid appeared to be a ceramide glucuronic acid (N-acyl dihydrosphingosine 1-glucuronic acid).

Flavobacterium↗
PubMed1978

Studies on the physical dependence potential of analgesics.

Influence of morphine on the fine structure of mitochondria in the cell of zona fasciculata of adrenal cortex in mice treated chronically with morphine pellets was studied using the electron microscope. The trnasformation of mitochondrial structure was observed 12 hours after morphine pellet implantation and the degree of transformation reached a maximum at 48 hours. These changes, however, disappeared within 4 days. On the 4th day after implantation, removal of the pellet or levallorphan challenge resulted in alteration of the mitochondria with evidence of withdrawal syndrome. Reinjection of morphine to the mice immediately after removal of the pellet, however, prevented the appearance of such mitochondrial transformation. Chlorpromazine or sodium pentobarbital did not affect on the transformation of mitochondria.

Adrenal Cortex↗