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Biomedical subjects

Y Iwami

Publications and source records attributed to Y Iwami.

At least 37 records · Page 2Linked to original sources
PubMed1996

Hormonal regulation of T-cell subsets in the oviduct: an immunohistochemical study using sex-hormone-treated chicken.

The present immunohistochemical study deals with dynamic alteration of T-cell subsets in the oviduct sex-hormone-treated chickens. Monoclonal antibodies (CT3, CT4, and CT8) specific for the chicken homologues of CD3, CD4, and CD8 were used in estrogen- or progesterone-treated chickens. In control animals, no lymphocytes appeared throughout the oviduct until 4 weeks of age. When 7-day-old chickens were injected with either diethylstilbestrol (DES) or (DES) plus progesterone, T cells immunoreactive for CT3 first infiltrated the oviduct at 12 hr after the hormone treatment. Their frequency of occurrence rose from 48 to 96 hr. Subsequently, CT3+ cells in the magnum declined in number per area coincident with the proliferation of albuminous glands in the lamina propria, while in the vagina no decline of T cells was observed. The population of T-cell subsets in the lamina propria of both the magnum and vagina was significantly higher in the DES-treated chickens than in DES plus progesterone-treated chickens. Among T-cell subsets CT8+ cells were more numerous than CT4+ cells throughout the study, this relative frequency being shared by normal adults. Depopulation of lymphocytes from the thymus, spleen and cecal tonsil, their mobilization to the circulating blood, and subsequent dynamic infiltration into the oviduct suggested that the sex hormones induced the traffic of T cells from the lymphoid organs into the oviduct.

Animals↗
PubMed1995

Simultaneous monitoring of intracellular pH and proton excretion during glycolysis by Streptococcus mutans and Streptococcus sanguis: effect of low pH and fluoride.

A system was developed by which 2',7'-bis(carboxyethyl)-4 or 5-carboxyfluorescein could be used to monitor intracellular pH at the same time that proton excretion was being measured. Streptococcal cells were loaded with the dye, and after the addition of glucose protons were excreted and the intracellular pH increased quickly and remained higher than the extracellular pH of 7.0. The excretion of protons stopped and the intracellular pH returned to the original level when glucose was depleted. The intracellular level of ATP remained high during glucose metabolism and decreased with the depletion of glucose. At extracellular pH of 5.5, and 5.0, the intracellular pH of fasting cells was higher than the extracellular pH value. After addition of glucose there were initial lags of proton excretion and of increases in intracellular pH at the acidic extracellular pH values. In the presence of fluoride, a lag in proton excretion and a simultaneous decrease in intracellular pH were observed, indicating a partial and transient inhibition of proton-ATPase activity.

Adenosine Triphosphate↗
PubMed1995

Mechanism of inhibition of glycolysis in Streptococcus mutans NCIB 11723 by chlorhexidine.

Inhibition of the rate of acid production from glucose by the cells of Streptococcus mutans NCIB 11723 was directly related to the concentrations of 0.075 to 0.20 mM chlorhexidine. Lactate production was inhibited to a greater extent than acetate and formate. Quantification of glycolytic intermediates revealed that the steps in glycolysis inhibited by chlorhexidine were the reactions catalyzed by phosphofructokinase and glyceraldehyde 3-phosphate dehydrogenase and/or phosphoglycerate kinase. However, the activities of these enzymes were not decreased in cells treated with the inhibitor. It was demonstrated that chlorhexidine caused leakage of metabolites from the cells. Our results indicate that the decreased rate of glycolysis caused by chlorhexidine is due to the leakage of metabolic intermediates and not to direct effects on enzymes involved in glycolysis by S. mutans NCIB 11723.

Acetates↗
PubMed1995

Stoichiometry of fluoride release from fluorhydroxyapatite during acid dissolution.

Release of F from fluorhydroxyapatite (FHAp) during acid dissolution was studied to validate the use of this mineral as a plaque reservoir of F. FHAp minerals having a wide range of F concentrations were synthesised by aqueous precipitation, and samples repeatedly exposed to 50 mM lactic acid solution, pH 4.5, or similar lactic/acetic/formic acid mixtures, until dissolution was complete. While the Ca/P ratio in solution remained relatively constant and close to the ratio in the solid, the solution F/Ca ratio invariably changed during dissolution. During initial stages the F/Ca solution ratio was lower than in the solid but rose to reach a plateau higher than in the solid as dissolution progressed, an effect that was more pronounced with low-F FHAp. With these minerals the plateau F/Ca level never reached 0.2, suggesting that a F-enriched FHAp rather than pure fluorapatite precipitates during dissolution. It is concluded that a high-F FHAp mineral would best serve as an apatitic plaque reservoir of F.

Acetates↗
PubMed1995

Effect of sucrose monolaurate on acid production, levels of glycolytic intermediates, and enzyme activities of Streptococcus mutans NCTC 10449.

We studied the mechanism by which the antimicrobial compound sucrose monolaurate inhibits Streptococcus mutans NCTC 10449 by determining its effect on the rate of acid production from glucose and sucrose and the intracellular and extracellular levels of glycolytic intermediates. Sucrose monolaurate was more effective than either sodium laurate or sodium fluoride in inhibiting acid production at pH 7.0 from glucose. Inhibition of acid production was the same when either glucose or sucrose was the carbon source and in the presence or absence of oxygen. Quantitative analysis of various glycolytic intermediates revealed that the steps inhibited by sucrose monolaurate were the reactions catalyzed by phosphofructokinase and glyceraldehyde 3-phosphate dehydrogenase and/or phosphoglycerate kinase. Since the activities of these enzymes in cell-free extracts were not decreased by the addition of sucrose monolaurate, the inhibition of acid production could not be ascribed to direct effects on the enzymes. A decrease in the rate of acid production with corresponding elevations in the extracellular levels of glycolytic intermediates indicates that sucrose monolaurate inhibits S. mutans by altering the permeability of the cell membrane, which causes a loss of important metabolites.

Anti-Infective Agents, Local↗
PubMed1995

The effect of fluorhydroxyapatite-derived fluoride on acid production by streptococci.

The effect of fluoride derived from fluorhydroxyapatite (FHAp) minerals on bacterial glycolysis under aerobic and strictly anaerobic conditions was studied to validate the claims that this mineral could be used as a reservoir of fluoride in plaque. To isolate the direct effect of fluoride on bacterial glycolysis from that of an indirect pH-buffering effect of hydroxyl or phosphate ions which are also dissolved from the mineral, we equalized the pH-fall time course of reactions by manually adding KOH or HCl. This ensured that pH effects on glycolysis were minimized. Under controlled pH-fall and strictly anaerobic conditions, fluoride derived from the dissolution of FHAp containing more than 30,100 ppm fluoride (i.e., when the substitution of OH by F in the mineral was greater than 80%) had a direct inhibitory effect on lactic acid production in Streptococcus mutans. Under free pH-fall and strictly anaerobic conditions, increasing amounts of fluoride in FHAp (starting as low as 2000 ppm fluoride), appeared to have a pronounced indirect inhibitory effect on lactic acid production. This was probably mediated through a reducing pH buffer effect of the mineral. Even in the presence of high-fluoride FHAp, only 0.01 to 0.025 mmol/L fluoride was found in the reaction mixtures, a probable result of non-stoichiometric dissolution of FHAp. In spite of such low levels of fluoride, marked inhibitory effects on bacterial glycolysis were demonstrated. The results of this study suggest that high-fluoride FHAp may serve as a reservoir of fluoride for the inhibition of anaerobic acid production by S. mutans.

Anaerobiosis↗
PubMed1992

Acid production by streptococci growing at low pH in a chemostat under anaerobic conditions.

Streptococcus mutans and other oral streptococci were grown in continuous culture under strictly anaerobic conditions. When the cultural pH was kept at 7.0, the main acid products were formate and acetate, as reported previously. However, more lactate was produced at pH values of 5.5 or 6.0, with a concomitant decrease in formate and acetate production. This change in fermentation products could partly be ascribed to a change in intracellular pH and difference in the pH optima between pyruvate formate-lyase (PFL) and lactate dehydrogenase (LDH). At extracellular pH values of 7.0 and 5.5, the intracellular pH values of S. mutans NCIB 11723 were 7.5 and 6.6, respectively. The pH optima of PFL and LDH were 7.8 and 5.5-6.3, respectively. The cells had also a larger amount of LDH during growth at pH 5.5 than at pH 7.0.

Anaerobiosis↗
PubMed1991

Metabolism of intracellular polysaccharide in the cells of Streptococcus mutans under strictly anaerobic conditions.

Streptococcus mutans, which had accumulated glycogen-like iodophilic intracellular polysaccharide (IPS), produced large amounts of formate, acetate and ethanol from the IPS by pyruvate formate-lyase (PFL) under strictly anaerobic conditions without exogenous sugar. Under aerobic conditions, the same S. mutans produced exclusively lactate and pyruvate from the IPS because of the inactivation of PFL by oxygen. The total amount of acid produced under anaerobic conditions was larger than that under aerobic conditions. The analysis of intracellular glycolytic intermediates revealed that levels of fructose 1,6-bisphosphate (lactate dehydrogenase (LDH) activator) and glyceraldehyde 3-phosphate and dihydroxyacetone phosphate (PFL inhibitors) were low when IPS was used as a glycolytic substrate, implying that PFL functions more efficiently than LDH in IPS metabolism. These findings suggest that the PFL pathway contributes to the acid production from IPS, and may explain partially why the acids in starved dental plaque are mainly acetate and formate.

Acetates↗
PubMed1990

Biochemical mechanisms of enhanced inhibition of fluoride on the anaerobic sugar metabolism by Streptococcus sanguis.

The effect of fluoride on acid production by Streptococcus sanguis ATCC 10556 was compared under anaerobic and aerobic conditions. The rate of acid production under constant-pH and pH-free-fall conditions was determined during glucose metabolism by resting cells. Anaerobic glycolysis was inhibited more strongly by fluoride than was aerobic glycolysis. Intracellular levels of 3-phosphoglyceric, 2-phosphoglyceric, and phosphoenolpyruvic acids were lower under anaerobic conditions than under aerobic conditions. Thus, S. sanguis had a low phosphoenolpyruvate (PEP) potential under anaerobic conditions. This low PEP potential was suggested to account for the more effective fluoride inhibition of enolase and, consequently, the reduced transport of sugar by the PEP-dependent phosphotransferase system of this micro-organism.

Fluorides↗
PubMed1990

[Recognition of orthodontic patients and their parents about the orthodontic treatment and results--a questionnaire method].

This study was undertaken to investigate the desire and consciousness of orthodontic patients and their parents on the content and effect of orthodontic treatment. The subjects were 362 post-treatment patients and 353 of their parents, who answered the questionnaires. The following conclusions were obtained: 1. 49% of the patients and 16% of the parents of the patients thought of giving up the treatment while the patients were under the orthodontic treatment. The main reasons were the discomfort of orthodontic appliances, long treatment period, and the absence from school. 2. 55% of the patients felt uneasy about a change of the occlusion for the worse after removal of the orthodontic appliances, and 60-70% of the patients and parents had forgotten the necessity of the retainer after active orthodontic treatment. 3. Both patients and parents hoped to finish the orthodontic treatment by the end of junior high school. 4. About 50% of the parents preferred the university hospital and about 45% preferred a private dental office which was convenient for attending as an outpatient. 5. About 70% of the patients and parents were satisfied with occlusion after orthodontic treatment, and 33% of the patients and 61% of the parents were satisfied with the orofacial appearance after treatment. 6. About 9% of the patients hoped to keep secret their history of orthodontic treatment. 7. About 35% of the patients and 60% of the parents would recommend people with malocclusions to receive orthodontic treatment. About 80% of the patients would make their own children receive the orthodontic treatment if needed. 8. About 90-95% of the patients and parents were pleased with orthodontic treatment.

Humans↗
PubMed1990

Bonding ability of light cured composite resin to enamel and dentin promoted by various bonding systems--microleakage and bond strength studies.

The purpose of this study was to estimate bond strength between light cured composite resin and enamel or dentin, and marginal sealing ability of composite resin promoted by five commercial bonding systems. At first, tensile bond strength between light cured composite resin and enamel or dentin promoted by these bonding systems were measured. Next, class V cavities were prepared at cementoenamel junction of extracted human molars and filled with light cured composite resin, using the same bonding systems. Microleakage around the restoration was estimated by dye penetration test. All bonding systems presented high bond strength and good marginal sealing between composite resin and enamel. The bonding systems which presented high bond strength between composite resin and enamel or dentin inhibited microleakage around restoration effectively. However, no bonding system could inhibit microleakage completely at the cementum/dentin-composite resin interface.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

Difference in amounts between titratable acid and total carboxylic acids produced by oral streptococci during sugar metabolism.

The acid produced by the resting cells of Streptococcus mutants NCTC 10449 and HS 6 and S. sanguis ATCC 10556 during sugar metabolism was estimated with a pH-stat and a carboxylic acid analyzer. Lactic, formic, acetic, pyruvic, and carbonic acids were detected in the reaction mixtures, but propionic, citric, succinic, iso-butyric, butyric, iso-valeric, and valeric acids were not detected. The amount of titratable acid estimated by alkaline titration with the pH-stat was larger than the amount of total carboxylic acids estimated with the carboxylic acid analyzer. The difference in quantity between the titratable and the total carboxylic acids increased significantly with an increase in the period of incubation with sugar. Moreover, the value of the alkaline titration of standard lactic, formic, acetic, and pyruvic acids was equal to the amount analyzed with the carboxylic acid analyzer. The results indicated that these two streptococci produced not only these carboxylic acids but also other acid(s), possibly non-carboxylic acid(s), during their sugar metabolism.

Carboxylic Acids↗
PubMed1985

Regulation of glycolytic rate in Streptococcus sanguis grown under glucose-limited and glucose-excess conditions in a chemostat.

The biochemical mechanisms of the acidogenic potential of Streptococcus sanguis ATCC 10556 grown in glucose-excess and glucose-limited continuous culture were studied. The rate of acid production during the glucose metabolism by the cells grown under glucose limitation (glucose-limited cells) was 2.1 to 2.6 times that by the cells grown in an excess of glucose (glucose-excess cells). When the glucose-limited cells were metabolizing glucose, intracellular concentrations of glucose 6-phosphate, fructose 6-phosphate, 3-phosphoglycerate, and pyruvate were higher, and that of glyceraldehyde 3-phosphate was lower, than those when the glucose-excess cells were metabolizing glucose. The levels of fructose 1,6-bisphosphate and dihydroxyacetone phosphate were not significantly different between these cells. The activities of glucose-phosphoenolpyruvate phosphotransferase system in decriptified cells and glyceraldehyde-3-phosphate dehydrogenase in cell-free extracts of the glucose-limited cells were higher than those in the glucose-excess cells. The activities of glucokinase, phosphoglycerate kinase, and pyruvate kinase in cell-free extracts of these cells were not different significantly. We conclude that the high glycolytic activity of the glucose-limited cells results from the increase in the synthesis of glucose-phosphoenolpyruvate phosphotransferase and glyceraldehyde-3-phosphate dehydrogenase.

Culture Media↗
PubMed1983

Hydrogen peroxide excretion by oral streptococci and effect of lactoperoxidase-thiocyanate-hydrogen peroxide.

Approved type strains of Streptococcus sanguis, S. mitis, S. mutans, and S. salivarius were grown under aerobic and anaerobic conditions. The rate of hydrogen peroxide excretion, oxygen uptake, and acid production from glucose by washed-cell suspensions of these strains were studied, and the levels of enzymes in cell-free extracts which reduced oxygen, hydrogen peroxide, or hypothiocyanite (OSCN-) in the presence of NADH or NADPH were assayed. The effects of lactoperoxidase-thiocyanate-hydrogen peroxide on the rate of acid production and oxygen uptake by intact cells, the activity of glycolytic enzymes in cell-free extracts, and the levels of intracellular glycolytic intermediates were also studied. All strains consumed oxygen in the presence of glucose. S. sanguis, S. mitis, and anaerobically grown S. mutans excreted hydrogen peroxide. There was higher NADH oxidase and NADH peroxidase activity in aerobically grown cells than in anaerobically grown cells. NADPH oxidase activity was low in all species. Acid production, oxygen uptake, and, consequently, hydrogen peroxide excretion were inhibited in all the strains by lactoperoxidase-thiocyanate-hydrogen peroxide. S. sanguis and S. mitis had a higher capacity than S. mutans and S. salivarius to recover from this inhibition. Higher activity in the former strains of an NADH-OSCN oxidoreductase, which converted OSCN- into thiocyanate, explained this difference. The change in levels of intracellular glycolytic intermediates after inhibition of glycolysis by OSCN- and the actual activity of glycolytic enzymes in cell-free extracts in the presence of OSCN- indicated that the primary target of OSCN- in the glycolytic pathway was glyceraldehyde 3-phosphate dehydrogenase.

Depression, Chemical↗