Search

Power transmission characteristics for the 5‐μm band CO laser through chalcogenide glass fibers have been measured. With 1000‐μm core diameter, 1‐m‐long, As‐S and Ge‐As‐S glass fibers, the maximum transmitted powers have reached as high as 226 and 180 W, respectively. By applying antireflection coatings to the fibers, drastic increases in transmission efficiency have been demonstrated.

The purpose of this study was to investigate whether there are any differences in tooth movement or in the response of periodontal tissue to orthodontic force when the force is applied at different times of the day. One hundred 6-week-old male Wistar rats were divided into one control group without force application and three experimental groups based on the time of day the force was applied to the upper first molars. Animals in the whole-day group received force continuously throughout the experimental period, while animals in the light- and dark-period groups received force only during the light (07:00-19:00) or dark period (19:00-07:00), respectively. Tooth movement was measured using the occlusal view of a precise plaster model with a profile projector. Periodontal tissues were evaluated histologically. The time course of tooth movement varied among the groups. Tooth movement over 21 days in the whole-day and light-period groups was about twice that as in the dark-period group. The formation of new bone on the tension side in the whole-day and light-period groups was more than twice that as in the dark-period group. On the pressure side, more osteoclasts appeared on the alveolar bone in the whole-day and light-period groups than in the dark-period group. The light-period group showed less extensive hyalinization of the periodontal ligament (PDL) than the whole-day group. The area of root resorption on day 21 also varied among the groups. Interference by masticatory forces did not seem to be a principal cause of the decreased tooth movement in the dark-period group. These results indicate that there are considerable variations in tooth movement and in the response of periodontal tissue to orthodontic force when the force is applied at different times of the day in rats. The results suggest that diurnal rhythms in bone metabolism have important implications in orthodontic treatment.

The purpose of this study was to determine whether there is any difference in orthodontic tooth movement when the orthodontic force is applied at different times of the day. Twenty-four rats were divided into three experimental groups based on the time of day that maxillary expansive force was applied; i.e., the force was applied continuously throughout the entire experimental period of 21 days in animals in the whole-day group; animals in the dark-period group and the light-period group received force only during the dark period (19:00-07:00) or the light period (07:00-19:00), respectively. Maxillary expansion in the light-period group was about 2 times greater than that in the dark-period group on day 21. There was no significant difference in expansion between the light-period group and the whole-day group. An experiment that used chronologic labeling with NTA-Pb revealed that there was greater formation of new bone on the tension side in the light-period group than in the dark-period group. There was no significant difference in the width of the palate among the three groups. These results indicate that there is a diurnal variation in tooth movement in response to orthodontic external force and that the application of force during the animal's rest period may be more effective than that while it is active.

The effects of 3 bisphosphonates, AHBuBP, AHPrBP, and Cl2MBP on cell growth, alkaline phosphatase (ALP) activity, mineralization, and prostaglandin E2 (PGE2) synthesis in the clonal osteoblast-like cell line MC3T3-E1 were studied. These bisphosphonates had essentially similar effects on growth and the osteoblastic functions of the cells, i.e., they had no inhibitory effects on cell growth except at higher concentrations, they increased ALP activity, and inhibited PGE2 production. In the presence of AHBuBP, ALP activity was higher than that in the control after day 6 of culture. Lower concentrations of AHBuBP slightly facilitated mineralization by the cells. It is probable that bisphosphonates enhance the functions of osteoblasts in certain concentration and that the inhibition of endogenous PGE2 production may be involved in the mechanism of action of bisphosphonates.

The aim of this study is to evaluate the performance of a newly developed Ni-free SMA wire as an orthodontic wire by comparing with a Ni–Ti wire. A Ti–Nb–Al superelastic wire or an orthodontic superelastic wire (Ni–Ti wire) was set in the mouth of male Wistar-strain rats, and orthodontic palatal movement of maxillary first molars was performed with an initial load of 15 gf. The amount of tooth movement was measured and periodontal structures were observed using microfocus X-ray CT radiographs. There was no significant difference in the amount of movement between the Ti–Nb–Al group and the Ni–Ti group. Microfocus X-ray CT observation revealed no morphological differences between the two groups. Our results indicate that the Ti–Nb–Al wire can be a comparable orthodontic wire to the Ni–Ti wire.

The aim of this study was to confirm the usefulness of magnets for orthodontic tooth movements. Computer simulation was performed to design magnets, especially for this new animal model. The flux density and attractive force of samarium–cobalt (Sm–Co) magnet and neodymium–iron–boron (Nd–Fe–B) magnet were examined. The magnet or titanium was bonded on the rat maxillary first molars. The initial distance between magnets/titanium was 1.0 mm (experimental group I/control group I, Exp. I/ Cont. I) or 1.5 mm (experimental group II/control group II, Exp. II/Cont. II). The amount of tooth movement was measured and periodontal structures were observed using microfocus X-ray CT radiographs. The distance between magnets decreased in both experimental groups. Tooth movement in Exp. II was slower than Exp. I. Horizontal sections of microfocus CT radiographs showed narrow periodontal space without root resorption on the pressure side in both experimental groups. Attractive force of the newly designed magnets caused effective tooth movement without any pathological changes in rats.

Root resorption associated with tooth movement is an unsolved problem in orthodontics. If such root resorption could be prevented, it would be an important contribution toward reducing risk factors in orthodontic treatment. The purpose of this study was to examine the effects of the topical administration of a bisphosphonate, risedronate, which is known to be a potent blocker of bone resorption, on root resorption during tooth movement and on the repair of the resorbed root surface after tooth movement in rats. In the first experiment, both the right and left upper first molars were moved buccally with a standardized expansion spring under administration of risedronate. After day 7, extensive root resorption had occurred on the control side, and the area of root resorption reached a maximum on day 14. The topical administration of risedronate caused a significant and dose-dependent inhibition of root resorption after the orthodontic force was applied. In the second experiment, the right and left upper molars were first moved buccally for 3 weeks. Risedronate treatment began on the day the spring was removed. After the force was withdrawn, the resorbed root surfaces on both the control and risedronate-treated sides were gradually restored by apposition of repair cementum (cementoid). The topical administration of risedronate did not appear to inhibit the repair process of root resorption. These results suggest that the topical administration of risedronate may be useful in preventing root resorption of teeth during orthodontic treatment.

In orthodontics, undesirable movement of anchor teeth during tooth movement and relapse of moved teeth after treatment are the main causes of unsuccessful results. If these tooth movements could be prevented with pharmacological agents, a less complex orthodontic force system and less extensive retention would be required. The purpose of this study was to examine the effect of topical administration of a bisphosphonate (risedronate), a potent blocker of bone resorption, on orthodontic tooth movements in rats. In the first experiment, both the right and left upper first molars were moved buccally with a standardized expansion spring under administration of risedronate. Risedronate solution was injected into the sub-periosteum area adjacent to the left upper first molar. The right first molar served as a control with an injection of 0.9% NaCl solution. The topical administration of risedronate caused a significant and dose-dependent reduction of tooth movement after the orthodontic force was applied. In the second experiment, the right and left upper molars were first moved buccally for three weeks. The spring was then removed, and administration of risedronate was begun. The topical administration of risedronate inhibited relapse of the tooth in a dose-dependent manner. The administration of risedronate did not affect either overall growth of the animals or longitudinal growth of tibiae. These results suggest that topical application of risedronate may be helpful in anchoring and retaining teeth under orthodontic treatment.

MC3T3-E1 cells actively synthesized and released prostaglandin E 2 (PGE 2 ) during culture. PGE 2 release was minimal on day 9 and gradually increased with culture up to day 27. DNA content gradually increased until day 27. Alkaline phosphatase (ALP) activity increased up to day 15 and decreased thereafter. In contrast to the decrease in ALP activity, calcium accumulation increased rapidly after day 21, possibly due to mineralization by the cells. Indomethacin, a cyclooxygenase inhibitor, blocked PGE 2 production completely at concentrations higher than 0.3 μmol/L. In the presence of indomethacin (3 μmol/L), DNA content was slightly decreased on day 27. Furthermore, ALP activity on day 15 was greater than that of the control and this high activity was maintained until day 27. However, calcium accumulation was not affected by the addition of indomethacin. These results suggest that endogenous PGE 2 down-regulates ALP activity and slightly stimulates the proliferation of MC3T3-E1 cells as an autocrine mediator, although it does not directly influence the cells' mineralizing activity.

A long pulse one Joule excimer laser was used as a pumping source for stimulated Raman scattering in lead vapour and hydrogen. High efficiency Raman frequency conversion into blue-green region was obtained . A decrement of Raman conversion efficiency at high repetition rate was observed in a sealed Raman cell. A hydrogen gas circulating system was designed with gas pressure up to 50 Atm,it can be operated at high repetition rate without decrement of Raman conversion efficiency.

The ethanolic solution of Rhodamine 6G is used for dye lasers in the atomic vapor laser isotope separation (AVLIS) system. However, the water solution is preferable from the standpoint of easy treatment and safety. In this paper, we systematically investigated the laser efficiency of a Rhodamine 6G dye laser pumped by a frequency-doubled Nd:YAG laser, for various water-based solutions with surface-active agents and alcohols. By adding an appropriate amount of surface-active agent (Triton X or Emulgen) or alcohol (ethanol or propanol), we obtained almost the same level of laser efficiency as in the pure ethanolic solution. The improvement in the laser efficiency with these additives was attained by the deaggregation of nonradiative dimers. It was also confirmed that the water-based solution showed better performance against thermal distortion than the ethanolic solution, and was suitable for copper vapor laser (CVL) pumping.

Physical factors correlating with the Curie-Weiss temperatures of displacive-type f erroelectrics and antif erroelectrics were surveyed. For oxide compounds with perovskite and tungsten-bronze structures, the covalent bond energy between an A-site ion and an oxygen ion was found to show a high correlation with their Curie-Weiss temperatures, Effective charges of the ions in these compounds, which were estimated by an extended Sanderson's theory, supported highly covalent nature of their chemical bonding. Relation between Curie-Weiss temperatures and ion radii were also examined.

HTLV-IはATLの病因ウイルスであり,その伝播経路は夫婦間,母子間,そして輸血がある.輸血によって抗HTLV-I抗体の陽転したと思われる白血病の5症例について抗HTLV-I抗体(particle agglutination; PA, Western blotting; Wb),と血清中のIgG subclasses (IgGs.), β2-microglobulin (β2-m), fibronectin (FN)を測定し,その推移経過を検討した.その結果,1) 血清IgGs.は輸血前値に比較して一過性あるいは持続的にIgG1, IgG3値が増加し,2) 血清β2-m値はPA陽転時に一過性の増加がみられた.また,血清FN値も同時期に一過性の減少傾向がみられた.3) PA値は輸血後約1ヵ月以内に陽転した.4) Wbによる解析ではPA陽転初期からp19, p24, p53などの蛋白に対する抗体が認められ,陽転初期にそれらの抗体はIgM型優位で後にIgG型に移行した.5) HTLV-I感染における宿主のウイルス感染防御機構の初期反応の解明をするうえでこれらのパラメーターの検索は有意義と考えられた.

The kinetics of the solid-state reaction of strontium carbonate with anatase and rutile in air and carbon dioxide were studied by use of a thermobalance. The product was single-phase SrTiO3 in all cases. The relation between fraction reacted and time was fitted to the Jander equation and to the Carter equation for both anatase and rutile. For anatase the rate constant in carbon dioxide did not differ from that in air. The reaction rates for rutile in air and in carbon dioxide were ⅓ and ⅛ that for anatase, respectively. The In k vs 1/T relation for anatase gave two straight lines with different slopes having a break point at ∼820°C in both air and carbon dioxide. The Jander activation energies for anatase in the higher and lower temperature regions were ∼340 and ∼290 kj · mol−1, respectively, and those for rutile in air and carbon dioxide were 340 and 390 KJ · mol−1, respectively.

The covalent bond energy of the A-O bonding and the enthalpy of formation for perovskite-type oxides ABO3 were found to show high correlations with Curie points. Perovskite-type titanates with a lower covalent bond energy show higher Curie points, while those with low standard enthalpy of formation show low Curie points, or do not cause displacive transitions. The standard enthalpy of formation of perovskite oxides was inferred to be approximately equal to the sum of that of simple oxides.

Phase behavior of water-oil systems containing mixed nonionic surfactant or commercial surfactants, such as nonylphenylpoly (oxyethylene) ether, Tween 20 has been studied. In these systems, a three-phase region consisted of a water, a surfactant and an oil phases moves toward higher temperature with the decrease in a surfactant content. Accordingly, O/W-type emulsion can be inverted by not only the rise in temperature but increasing the surfactant content.The effect of added ionic surfactant on the phase behavior of a nonionic surfactant/water/oil system has been also studied. The three-phase region moves toward higher temperature and diminishes by adding a small amount of ionic surfactant to a nonionic surfactant/water/oil system. Moreover, the solubilization of water and oil in a surfactant phase is abruptly increased.

The effects of different B-site elements on the Curie points of the PbTiO3-Pb(M1/3Nb2/3)O3 and 0.99BaTi03-0.01Ba(M1/3Nb2/3)O3 series (M = Ca, Mn, Fe, Co, Ni, Cu, Zn), were examined. The Curie point was high when M was copper, while it was low when M was nickel. This was caused by the Jahn-Teller effect in the CuO6 octahedron keeping the Curie point high. For the 0.99BaTiO3-0.01 Ba(M1/3Nb2/3)O3 systems, the Curie points were correlated with axial ratioc/a.

The solid-state reaction of strontium sulfate with anatase and rutile was examined by isothermal and non-isothermal TGA/DTA and X-ray diffraction. The endothermic peak due to the reversible phase transition of SrSO 4 was observed by DTA in the vicinity of the endothermic peak due to the reaction. The product was only SrTiO 3 in all cases. The reaction mechanism was described by the Jander model. The rate constant for anatase was about twice as large as that for rutile. The relation between In k j and T −1 for anatase and rutile was discontinuous being linear either side of the phase transition temperature of SrSO 4 . The rate constant just above the transition temperature was enhanced 1.5 times with respect to that just below the temperature. The activation energy for the reaction of strontium sulfate with rutile was 354 and 435 kJ mol −1 in the higher and lower temperature regions respectively. In the reaction with anatase, the phase transition of anatase to rutile was also observed in about 30% of the fraction reacted at any temperature, and the rate constant was scattered from the In k j vs. T −1 curve, especially at high temperatures.

透析 (HD) 患者527名 (1988年1月) の血清中の抗HTLV-I抗体をゼラチン粒子凝集法 (particle agglutination test; PA法) およびWestern blotting (WB) 法にて測定し, 1984年5月332名, 1985年5月407名の結果と比較した. また, 1984年, 1985年, 1988年のPA陽性者の推移も合わせて検討した. 1986年11月より日本赤十字社にて抗HTLV-I抗体のスクリーニング検査が施行された. そこで, スクリーニング検査開始前, 後の抗体陽転者についても検討した. その結果,1. 1988年1月のHD患者のPA陽性率は6.8% (36/527名) で, 1984年5月の10.2%はやや高値であったが, 1985年5月の6.4%との差異は認められなかった. また, PA陽性例の陰転化は認められなかった.2. 1988年1月のPA陽性36名にWB解析を施行したところ, WB陽性は30名でWBによる陽性率は5.7% (30/527名) であった.3. 1985年5月から1988年1月までに5例のPA陽転例がみられた. 5例中2例はWB陽性でいずれも日赤による抗体検査が開始された1986年11月以前の輸血による陽転と推定された.4. また, 5例中3例はWB保留であり, 今後PA低力価領域でかつWB保留症例については経過観察とともにさらに検討を要すると思われた.

Isolated dental pulp tissues of rats were incubated in modified Tyrode buffer, and prostaglandin (PG) I2 and thromboxane (TX) A2 released into the medium were measured by radioimmunoassay as 6-keto-PGF1α and TXB2, respectively. Addition of 100 ng/ml 1, 25-dihydroxyvitamin D3 (1, 25- (OH) 2D3) to the incubation medium caused a significant inhibition of both PGI2 and TXA2 production, while vitamin D3 and 1α- (OH) D3 (100 ng/ml) had no effect. The effect was independent of incubation time and de novo protein synthesis because the co-incubation with cycloheximide (50 μM) did not block this inhibition. The release of PGI2 and TXA2 from pulp tissues was enhanced by increasing concentrations of Ca_??_ in the incubation medium (5.0 mM and 10.0 mM) and calcium-ionophore A23187 (10 μM), and these enhancing effects were also inhibited by 1, 25- (OH) 2D3 (100 ng/ml). In Ca_??_-free medium, on the other hand, a significant effect of 1, 25- (OH) 2D3 was not observed. A Ca_??_-entry blocker nifedipine (50 μM) similarly inhibited the basal and enhanced (by 10.0 mM Ca_??_ and 10 μM A23187) production of PGI2 and TXA2, and had no effect in Ca_??_-free medium. 1, 25- (OH) 2D3 as well as nifedipine did not affect PGI2 and TXA2 production in the cell-free homogenates of dental pulp tissues while indomethacin completely inhibited those productions, indicating that 1, 25- (OH) 2D3 exerted its effect on the step prior to the cyclooxygenase pathway which converts arachidonic acid to PGI2 and TXA2. These results suggest that 1, 25- (OH) 2D3 inhibits PGI2 and TXA2 biosynthesis in dental pulp tissue by acting like a Ca_??_-antagonist.

A simple and rapid method for the determination of macrophage activating factor is described. A new type of apparatus suitable for the measurement of macrophage chemiluminescence was devised, and the effect of lymphokines on macrophage activities was studied by measuring phorbol myristate acetate-induced luminol-dependent chemilunescence. An outstanding feature of the new apparatus is that the plastic dish used for the cell culture can be used as the vessel for the chemiluminescence reaction. When thioglycollate-elicited ICR mouse peritoneal macrophages were incubated with lymphokines, their ability to generate chemiluminescence increased rapidly, reaching a maximal level at about 4 h, and then it progressively decreased to the control level at 8 h. Although this increasing effect of lymphokines on macrophage chemiluminescence was short-lived, it could be seen at a latively low concentration, at which lymphokine-mediated cytotoxic activity of macrophages was not observed.

The kinetics of the solid-state reaction of strontium carbonate with anatase and rutile in air and carbon dioxide were studied by use of a thermobalance. The product was single-phase SrTiO3 in all cases. The relation between fraction reacted and time was fitted to the Jander equation and to the Carter equation for both anatase and rutile. For anatase the rate constant in carbon dioxide did not differ from that in air. The reaction rates for rutile in air and in carbon dioxide were ⅓ and ⅛ that for anatase, respectively. The In k vs 1/T relation for anatase gave two straight lines with different slopes having a break point at ∼820°C in both air and carbon dioxide. The Jander activation energies for anatase in the higher and lower temperature regions were ∼340 and ∼290 kj · mol−1, respectively, and those for rutile in air and carbon dioxide were 340 and 390 KJ · mol−1, respectively.

TiO2, Nb2O5, Ta2O5, BaTiO3 ceramics were irradiated by a KrF excimer laser in air. A drastic drop of the electrical resistivity was observed on the surfaces. The resistivity of the irradiated surfaces decreased with increasing temperature, which shows that they had changed into a semiconducting phase. This was determined to be n-type by measuring the thermo-electromotive power. The semiconducting property is due to lattice defects which result from ablation of oxygen atoms. When a XeCl excimer laser was used on originally pure oxides. the binary ceramic compounds changed also to semiconductor, but BaTiO3 did not. The energy density threshold of producing a semiconducting phase was correlated with interatomic bond energy of the oxides.TiO2, Nb2O5, Ta2O5, BaTiO3 ceramics were irradiated by a KrF excimer laser in air. A drastic drop of the electrical resistivity was observed on the surfaces. The resistivity of the irradiated surfaces decreased with increasing temperature, which shows that they had changed into a semiconducting phase. This was determined to be n-type by measuring the thermo-electromotive power. The semiconducting property is due to lattice defects which result from ablation of oxygen atoms. When a XeCl excimer laser was used on originally pure oxides. the binary ceramic compounds changed also to semiconductor, but BaTiO3 did not. The energy density threshold of producing a semiconducting phase was correlated with interatomic bond energy of the oxides.

The effect of incubation time with lymphokines on macrophage activities was studied by use of the phorbol myristate acetate-induced luminol-dependent chemiluminescence method and cytotoxicity test. When thioglycollate-elicited ICR mouse peritoneal macrophages were incubated with lymphokines, their ability to generate chemiluminescence increased biphasically during incubation. That is, within one day, it reached a maximal level at about 4 h (early response), and then progressively decreased to the control level. However, when the incubation time was further prolonged, it began to increase again, and reached about 2-fold the control level after 3 d (late response). The increase in the chemiluminescence of lymphokine-treated macrophages with increasing incubation time is not due to the increase in the macrophage cell numbers. In contrast to the clear biphasic increase in chemiluminescence, there was no clear biphasic increase in cytotoxicity in lymphokine-treated macrophages. The activities in the lymphokine supernatants to induce the early and the late chemiluminescent response in macrophages disappeared together with the activity to induce cytotoxicity, on dialysis at pH 2 for 24 h or on heating at 80°C for 30 min, but not at 56°C for 30 min. Although the lymphokines increasing macrophage chemiluminescence were separated into two fractions in Sephadex G-100 gel filtration, each fraction had both activities to induce the early and the late chemiluminescent response, and the major fraction largely corresponded to that of the activity to induce cytotoxicity. These results suggested that there is a lymphokine which alters macrophage chemiluminescence biphasically by itself, and it may be interferon-γ.

A drastic drop of the electrical resistivity was observed on a ferroelectric insulator BaTiO3 surface, after KrFlaser irradiation in air at atmospheric pressure. The temperature dependence of the resistivity was employed to demonstrate semiconducting behavior. Such behavior was seen when the resistance was measured in nitrogen. When measured in air, the semiconducting layer was oxidized and the insulating behavior restored.