• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.325-334
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• 2005

Changes in the rabbit Leydig cell from birth to adulthood were studied in New Zealand white rabbits of 1, 7, 21, 35, 49, 70, 105, 147, 196, and 252 days (n = 8 rabbits per group) of age. The objectives of this study were to understand the fate of the fetal Leydig cells, to determine the changes in serum testosterone levels, and leutenizing hormone-stimulated testosterone production per testis in vitro, and to quantify adult Leydig cells by number and average volume with age. Testes of rabbits were fixed by whole body perfusion using a fixative containing 2.5% glutaraldehyde in cacodylate buffer, processed and embedded in Epon-araldite. Using $1{\mu}m$ sections stained with methylene blue-azure II, qualitative and quantitative (stereological) morphological studies were performed. Testosterone levels in the incubation medium of luteinizing hormone-stimulated (100 ng/ml) testosterone secretion per testis in vitro, and in serum were determined by radioimmunoassay. The average volume of a testis of 1-day-old rabbits was determined as $0.0073cm^3$ and the parameter increased linearly from birth to 252 days ($3.93cm^3$). The volume density of the seminiferous tubules increased with age from 33.76% at day 1 to 88.2% at day 252. The volume density of the interstitium represents 66.24% of the testicular parenchyma at day 1. This proportion progressively diminished during development to reach a value of 11.8% at day 252. The volume density of Leydig cells increased almost linearly from birth (0.001%) to 252 days (2.62%). Leydig cell mass per testis increases from 0.0012 mg to 0.25 mg between days 1 and 35, from 2.66 mg to 44.3 mg between days 49 and 105 and from 65.42 mg and 102.9 mg between days 147 and 252. The absolute numbers of adult Leydig cells per testis increased linearly from birth to 252 days. The average volume of adult Leydig cell on days 1, 7, 21 and 35 was not significantly different; a gradual and continued increase was observed thereafter, reaching a 3-fold increase at 196 and 252 days. Serum testosterone concentrations were not significantly different at day 1 compared days 7, 21, 35. Significant increases were observed at days 49 and 70. Values at days 70 and 105 and days 147, 196, and 252 were not significantly different. LH-stimulated testosterone production per testis in vitro was significantly different at day 1 compared days 7, 21, 35. Significant increases were observed at days 49 and 70. Hormonal values at days 105, 147, 196, and 252 were not significantly different. These data suggested Leydig cell developmental phase can be classified: a neonatal phase (1-7 days), a prepubertal phase (14-49 days) and an adult phase (70-252 days). Immature and mature adult Leydig cells, initially detected at days 7 and 49, respectively, and mature adult Leydig cells were abundant Leydig cell type according to the number and absolute volume per testis form day 49 onwards.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.332-340
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• 2001

Flowable composite resin has lower filler content, increased flow, and lower modules of elasticity. It is suggested that flowable composite resin can be bonded to the tooth structure intimately and absorb or dissipate the stress. Therefore, it may be advantageous to use flowable composite resin for the base material of class II restoration and for the class V restoraton. The purpose of this study was to evaluate the microleakage and shear bond strength of four flowable composite resins (Aeliteflo, Flow-It, Revolution, Ultraseal XT Plus) compared to Z100 using Scotchbond Multi Purpose dentin bonding system. To evaluate the microleakage, notch-shaped class V cavities were prepared on buccal and lingual surfaces of 80 extracted human premolars and molars on cementum margin. The teeth were randomly divided into non-thermocycling group (group 1) and thermocycling group (group 2) of 40 teeth each. The experimental teeth of each group were randomly divided onto five subgroups of eight samples (sixteen surfaces). The Scotchbond Multi-Purpose and composite resin were applied for each group following the manufacturer's instructions. the teeth of group 2 were thermocycled five hundred times between 5$^{\circ}C$ and 55$^{\circ}C$. The teeth of group 2 were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, and sectioned longitudinally with a diamond saw. The dye penetration on each of the specimen were observed with a stereomicioscope at $\times$20 magnification. To evaluate the shear bond strength, 60 teeth were divided into five groups of twelve teeth each. The experimental teeth were ground horizontally below the dentinoenamel junction, so that no enamel remained. After applying Scotchbond Multi-Purpose on the dentin surface, composite resin was applied in the shape of cylinder. The cylinder was 4mm in diameter and 2mm in thickness. Shear bond strength was measured using Instron with a cross-head speed of 0.5mm/min. After shear bond strength measurement, mode of failure was evaluated with a stereomicroscope at $\times$30 magnification. All data were statistically analyzed by One Way ANOVA and Student-Newman-Keuls method. The correlation between microleakage and shear bond strength was analyzed by linear regression. The results of this study were as follows ; 1. In non-thermocycling group, the leakage value of Z100 was significantly lower than those of flowable composite resins at the enamel and dentin margin, margin, except that Revolution showed the lower leakage value than that of Z100 at the dentin margin (p<0.05). 2. In thermocycling group, the leakage values of Z100 and Ultraseal XT Plus were lower than those of other subgroup at the enamel and dentin margin, except that Flow-It showed the lower leakage value than that of Ultraseal XT Plus at the dentin margin (p<0.05). 3. The leakage value of Z100 and Ultraseal XT Plus in thermocycling group were not higher than that in non-thermocycling group at the enamel margin. The leakage value of Z100 in thermocycling group was not higher than that in non-thermocycling group at the dentin margin (p<0.05). 4. As for the shear bond strength measurement, there were no statistically significant differences among groups (p<0.05). The shear bond strengths given in descending order were as follows: Z100(16.81$\pm$2.98 MPa), Flow-It(14.8$\pm$4.43 MPa), Aeliteflo(14.34$\pm$3.69 MPa), Revolution(13.46$\pm$4.23 MPa), Ultraseal XT Plus(12.83$\pm$3.16 MPa). 5. Failure modes of all specimens were adhesive failures. 6. There was no correlation between microleakage and shear bond strength.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.522-529
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• 2007

The purpose of this study was to compare the apical leakage of the root canal filled with the System B and the EndoTwinn(the combined application of heat and ultrasonic vibration). Sixty extracted premolars with straight root were cleaned and shaped to size 35. Group SB was obturated using System B and Group ET was filled with EndoTwinn. A size 35 of 0.06 tapered gutta-percha and Adseal were used and the plugger which could be introduced to 4 mm short of working length was selected in the obturation procedure. As the positive control, Group PC was not filled. In Group SB, ET and PC, all external surfaces of each tooth were coated with nail varnish leaving only 1 mm area around the apical foramen. In the negative control of Group NSB and Group NET, all of external tooth surface including apical foramen was coated with the nail varnish. The specimens were immersed in methylene blue dye solution for 2 days. Then the specimens were sectioned at each 1 mm from apex to 5 mm level. The final score of one specimen was given by summing up of the points at all levels. The dye leakage of Group ET was significantly less than that observed in Group SB (p < 0.05). And the frequency of gutta-percha pulling out from root canal when the plugger was removed was more often with the System B than with EndoTwinn but there was no significant difference.

• The Journal of Internal Korean Medicine
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• v.18 no.2
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• pp.1-26
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• 1997

Chunggeumtang has been used in Korea for many centuries as a treatment for respiratory disease. The effect of Chunggeumtang on tracheal smooth muscle is not konwn. The purpose of the present study is to determine the effect of Chunggeumtang on histamine and acetylcholine induced tracheal smooth muscle contraction in rats and guinea pigs. Guinea pig(500g, male) and Sprague Dawley rats (250g, male) were killed by $CO_2$ exposure and a segment (8-10mm) of the thoracic trachea from each rat and guinea pig was cut into equal swegments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force diplacement transducers under 0.5g loading tension. The dose of histamine (His) and acetylcholine (Ach) which evoked 50% of maximal response ($ED_{50}$) was obtained from cumulative dose response curves for histamine and acetylcholine($10^{-7}{\sim}10^{-4}M$). Contractions evoked by His ($ED_{50}$) and Ach ($ED_{50}$) were inhibited significantly by Chunggeumtang. In guinea pig tracheal smooth muscle, the mean percent inhibition of acetylcholine induced contraction was $6.1%after\;30{\mu}l/ml$ Chunggeumtang, and 49.4% (p<0.01) after $100{\mu}l/ml$ Chunggeumtang. In rat tracheal smooth muscle, the mean percent inhibition of acetylcholine induced contraction was $6.7%\;after\;30{\mu}l/ml$ Chunggeumtang, and $54.2%\;(p<0.01)\;after\;100{\mu}l/ml$ Chunggeumtang. Also, in guinea pig tracheal smooth muscle, the mean percent inhibition of histamine induced contraction was $30.6%\;(p<0.05)\;after\;30{\mu}l/ml$ Chunggeumtang, and $53.0%\;(p<0.01)\;after\;100{\mu}l/ml$ Chunggeumtang. In rat tracheal smooth muscle, the mean percent inhibition of histamine induced contraction was $24.1%\;(p<0.05)\;after\;30{\mu}l/ml$ Chunggeumtang, and $55.3%\;(p<0.01)\;after\;100{\mu}l/ml$ Chunggeumtang. Propranolol and indomethacin($10^{-7}M$) slightly but significantly attenuated the inhibitory effects of Chunggeumtang. Following treatment with propranolol, the mean percent inhibition caused by $100{\mu}l/ml$ Chunggeumtang fell to 27.6% in guinea pig induced by acetylcholine contraction and by $100{\mu}l/ml$ Chunggeumtang fell to 28.7% (p<0.05) in rat induced by acetylcholine contraction and the mean percent inhibition caused by $100{\mu}l/ml$ Chunggeumtang fell to 16.2% in guinea pig induced by histamine contraction and by $100{\mu}l/ml$ Chunggeumtang fell to 28.7% (p<0.05) in rat induced by histamine contraction. Indomethacin, the mean percent inhibition caused by $100{\mu}l/ml$ Chunggeumtang fell to 20.0% in guinea pig induced by acetylcholine contraction and by $100{\mu}l/ml$ Chunggeumtang fell to 16.9% (p<0.05) in rat induced by acetylcholine contraction and the mean percent inhibition caused by $100{\mu}l/ml$ Chunggeumtang fell to 16.4% in guinea pig induced by histamine contraction and by $100{\mu}l/ml$ Chunggeumtang fell to 23.1% (p<0.05) in rat induced by histamine contraction. Methylene blue($10^{-7}M$) did not significantly alter the inhibitory effect of Chunggeumtang. Also, I could find the effects of Chunggeumtang and Chunggeumtanggamorphine on the tracheal smooth muscle in guinea pig and rat did not change significantly. These results indicate that Chunggeumtang can relax histamine and acetylcholine-induced contraction of guinea pig and rat tracheal smooth muscle, and that this inhibition involves sympathetic effects and the release of cyclooxygenase products.

• Clean Technology
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• v.25 no.2
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• pp.129-139
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• 2019

Bamboo is an evergreen perennial plant, and it is known as one of the most productive and fastest-growing plants in the world. It grows quickly in moderate climates with only moderate water and fertilizer. Traditionally in Asia, bamboo is used for building materials, as a food source, and as versatile raw materials. Bamboo as a biomass feedstock can be transformed to prepare activated carbon using the thermal treatment of pyrolysis. The effect of process variables such as carbonization temperature, activation temperature, activation time, the amount of steam, and the mixing ratio of phosphoric acid and bamboo were systematically investigated to optimize the preparation conditions. Steam activation was proceeded after carbonization with a vapor flow rate of $0.8{\sim}1.8mL-H_2O\;g-char^{-1}\;h^{-1}$ and activation time of 1 ~ 3 h at $700{\sim}900^{\circ}C$. Carbon yield and surface area reached 2.04 ~ 20.59 wt% and $499.17{\sim}1074.04m^2\;g^{-1}$, respectively, with a steam flow rate of $1.4mL-H_2O\;g-char^{-1}\;h^{-1}$ for 2 h. Also, the carbon yield and surface area were 24.67 wt% and $1389.59m^2\;g^{-1}$, respectively, when the bamboo and phosphoric acid were mixed in a 1:1 weight ratio ($700^{\circ}C$, 2 h, $1.4mL-H_2O\;g-char^{-1}\;h^{-1}$). The adsorption of methylene blue into the bamboo activated carbon was studied based on pseudo first order and second order kinetics models. The adsorption kinetics were found to follow the pseudo second order model, which is governed by chemisorption.

• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.158-174
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• 2002

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP$^{TM}$ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501$^{TM}$ (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek$^{TM}$ Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP$^{TM}$ (Bisco) 200mW/$\textrm{cm}^2$ (V2), 400mW/$\textrm{cm}^2$ (V4), 600mW/$\textrm{cm}^2$ (V6), Pulse-delay (200 mW/$\textrm{cm}^2$ 3 seconds, 5 minutes wait, 600mW/$\textrm{cm}^2$ 30seconds, VPD) and Optilux 501$^{TM}$ (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens V2, Y4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5 each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes : V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD , OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test far microleakage values. The results were as follows : . Polymerization shrinkage was increased with higher light intensity in groups using VIP$^{TM}$ (Bisco) : the highest with 600mW/$\textrm{cm}^2$, followed by Pulse-delay, 400mW/$\textrm{cm}^2$ and 200mW/$\textrm{cm}^2$ groups, The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501$^{TM}$ (Demetron/Kerr). . Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30. . Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP$^{TM}$ (Bisco). The microleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501$^{TM}$ (Demetron/Kerr) was used.