• 대한소아치과학회지
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• 제31권4호
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• pp.705-713
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• 2004

불소는 항우식 작용을 보이므로 치아의 우식 예방을 고려 한 진료가 이루어지면서 치면에 불화물을 도포하거나 불소 함유 구강세정액을 사용하거나 불소방출성의 수복재료를 적용하거나 하는 등의 우식억제 방법이 치과임상에서 빈번하게 적용되고 있다. 이에 본 연구는 불소 방출을 보이는 수복재료의 잇솔질 후 불소방출과 잇솔질로 인한 표면조도의 변화를 조사하기 위해 시행되었다. 7종의 불소를 방출하는 수복재료로 Fuji II LC Improved: FL, Compoglass F CG, Dyract AP: DR, F2000 : FT, Ariston: AT, Tetric: TR, 그리고 Gradia: GD를 연구재료로 사용하였다. 불소 방출은 10,000회의 잇솔질을 시행한 후 10일 동안의 방출량을 측정하였고, 표면조도는 40,000회의 잇솔질 후 중심선평균거칠기 Ra와 최대거칠기 Ry를 측정하였으며, 마모면은 주사전자현미경으로 관찰하였다. 잇솔질 후의 불소 방출량과 표면 관찰로부터 다음과 같은 결론을 얻었다. 1. 불소방출은 AT군, FL군 및 CF군의 경우에는 초기단계에 다량의 급격 한 방출을 보인 후 상대적으로 낮으면서도 지속적인 방출 양상을 보였지만, 나머지 시험군의 경우에는 초기단계로부터 낮으면서도 지속적인 방출을 보였다. 2. 불소방출은 약 40일 경과 후 안정적인 방출 양상을 나타냈으며, Tukey 분석 결과, AT군, 레진강화 GIC의 FL군, 콤포머군 전부 및 불소방출성 콤포짓트 레진의 GD군과 TC군 사이에서 통계학적으로 방출량의 유의한 차이를 보였다(P<0.05). 3. 표면조도는 FT군에서 가장 크고 CF군에서 가장 작은 값을 보였으며, Tukey 분석 결과, FT군, AL군 및 FL군과 TC군, DR군, GD군 및 CF군 사이에서 통계학적으로 유의한 차이를 보였다(P<0.05).

• 폴리머
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• 제32권3호
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• pp.199-205
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• 2008

단백질 및 펩타이드의 서방형 약물전달체로서 소장점막하조직(SIS)으로 개질된 PLGA 담체를 제조하고자 하였으며, SIS/PLGA 담체는 용매 캐스팅/염 추출법에 의해 준비된 PLGA 담체에 SIS 용액을 첨가하여 단순 함침방법으로 제조하였다. 본 실험에서 사용된 돼지의 소장 점막층에서 유래된 SIS는 면역거부반응이 적어 생체재료로 널리 사용되고 있다. 제조된 PLGA 및 SIS/PLGA 담체를 SEM을 통한 표면 및 내부 관찰결과 두 담체 모두 열린 다공구조를 이루며, 특히 SIS/PLGA 담체는 PLGA 담체의 다공 내부에 SIS가 침투되어 작은 네트워크를 형성하고 있음을 확인하였다. 또한 단백질의 방출경향을 확인하기 위하여 형광이 결합된 소 혈청 알부민(FITC-BSA)을 PLGA 및 SIS/PLGA 담체에 담지시킨 후, 형광광도계를 통해 이들의 방출거동을 확인하였다. PLGA 담체와 비교할 때 SIS/PLGA 담체에서의 BSA의 방출은 초기방출량이 적고 지속적으로 일정량이 방출되는 거동을 확인할 수 있었으며 함량별 BSA 농도에 따른 SIS/PLGA 담체에서의 방출은 BSA의 양이 증가할수록 빠르고 많은 양이 방출되는 경향성 있는 방출패턴을 보임을 확인하였다. 결론적으로 PLGA 담체에 침투한 SIS 젤이 BSA의 급격한 초기방출을 억제하며, SIS로 개질된 PLGA 담체는 방출조절이 가능한 약물전달체로서 매우 유용할 것으로 사료된다.

• Biomolecules & Therapeutics
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• 제22권2호
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• pp.161-165
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• 2014

The main purpose of this study was to develop a novel, in situ gel system for sustained delivery of ranitidine hydrochloride. Ranitidine in situ gels at 0.2%, 0.5%, and 1.0% gellan gum concentration (w/v) were prepared, respectively, and characterized in terms of preparation, viscosity and in vitro release. The viscosity of the gellan gum formulations in solution increased with increasing concentrations of gellan gum. In vitro study showed that the release of ranitidine from these gels was characterized by an initial phase of high release (burst effect) and translated to the second phase of moderate release. Single photon emission computing tomography technique was used to evaluate the stomach residence time of gel containing $^{99m}Tc$ tracer. The animal experiment suggested in situ gel had feasibility of forming gels in stomach and sustained the ranitidine release from the gels over the period of at least 8 h. In conclusion, the in situ gel system is a promising approach for the oral delivery of ranitidine for the therapeutic effects improvement.

• 약학회지
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• 제45권6호
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• pp.623-633
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• 2001

Various bupivacaine-loaded microspheres were prepared using poly(d,1-lactide) (PLA) and poly(d,1-lactic-co-glycolide) (PLGA) by a solvent evaporation method for the sustained release of drug. The effects of process conditions such as drug loading, polymer type and solvent type on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their drug loading, size distribution, surface morphology and release kinetics. Drug loading efficiency and yield of PLGA micro- spheres were higher than those of PLA microspheres. The prepared microspheres had an average particle size below 5${\mu}{\textrm}{m}$. The particle size range of microspheres was 1.65~2.24${\mu}{\textrm}{m}$. As a result of SEM, the particle size of PLA microspheres was smaller than that of PLGA microspheres. In morphology studies, microspheres showed a spherical shape and smooth surface in all process conditions. In thermal analysis, bupivacaine-loaded microspheres showed no peaks originating from bupivacaine. This suggested that bupivacaine base was molecular-dispersed in the polymer matrix of microspheres. The release pattern of the drug from microspheres was evaluated for 96 hours. The initial burst release of bupivacaine base decreased with increasing the molecular weight of PLGA, and the drug from microspheres released slowly. In conclusion, bupivacaine-loaded microspheres were successfully prepared from poly(d,1-lactide) and poly (d,1- lactic-co-glycolide) polymers with different molecular weights allowing control of the release rate.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1618-1622
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• 2006

Bacteriophage T7 gp4A' is a ring-shaped hexameric DNA helicase that catalyzes duplex DNA unwinding using dTTP hydrolysis as an energy source. To investigate the effect of single-stranded DNA (ssDNA) on the kinetic pathway of dTTP hydrolysis by the T7 DNA helicase complexed with ssDNA, we have first determined optimal concentration of long circular M13 single-stranded DNA and pre-incubation time in the absence of $Mg^{2+}$ which is necessary for the helicase-ssDNA complex formation. Steady state dTTP hydrolysis in the absence of $Mg^{2+}$ by the helicase-ssDNA complex provided $k_{cat}$ of $8.5\;{\times}\;10^{-3}\;sec^{-1}$. Pre-steady state kinetics of the dTTP hydrolysis by the pre-assembled hexameric helicase was monitored by using the rapid chemical quench-flow technique both in the presence and absence of M13 ssDNA. Pre-steady state dTTP hydrolysis showed distinct burst kinetics in both cases, indicating that product release step is slower than dTTP hydrolysis step. Pre-steady state burst rates were similar both in the presence and absence of ssDNA, while steady state dTTP hydrolysis rate in the presence of ssDNA was much faster than in the absence of ssDNA. These results suggest that single-stranded DNA stimulates dTTP hydrolysis reaction by T7 helicase by enhancing the rate of product release step.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2395-2407
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• 2022

The sodium-cooled fast reactor is among the innovative nuclear technologies selected in the framework of the development of Generation IV concepts, allowing the irradiation of uranium-plutonium mixed oxide fuels (MOX). A fundamental step for the safety assessment of MOX-fuelled pins for fast reactor applications is the evaluation, by means of fuel performance codes, of the integral thermal-mechanical behaviour under irradiation, involving the fission gas behaviour and release in the fuel-cladding gap. This work is dedicated to the performance analysis of an inner-core fuel pin representative of the ASTRID sodium-cooled concept design, selected as case study for the benchmark between the GERMINAL and TRANSURANUS fuel performance codes. The focus is on fission gas-related mechanisms and integral outcomes as predicted by means of the SCIANTIX module (allowing the physics-based treatment of inert gas behaviour and release) coupled to both fuel performance codes. The benchmark activity involves the application of both GERMINAL and TRANSURANUS in their "pre-INSPYRE" versions, i.e., adopting the state-of-the-art recommended correlations available in the codes, compared with the "post-INSPYRE" code results, obtained by implementing novel models for MOX fuel properties and phenomena (SCIANTIX included) developed in the framework of the INSPYRE H2020 Project. The SCIANTIX modelling includes the consideration of burst releases of the fission gas stored at the grain boundaries occurring during power transients of shutdown and start-up, whose effect on a fast reactor fuel concept is analysed. A clear need to further extend and validate the SCIANTIX module for application to fast reactor MOX emerges from this work; nevertheless, the GERMINAL-TRANSURANUS benchmark on the ASTRID case study highlights the achieved code capabilities for fast reactor conditions and paves the way towards the proper application of fuel performance codes to safety evaluations on Generation IV reactor concepts.

• Fisheries and Aquatic Sciences
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• 제13권4호
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• pp.343-349
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• 2010

The effects of osmotic stress on the non-specific immune response of Nile tilapia, Oreochromis niloticus, were investigated. Osmoregulatory mechanism of tilapia has been studied, but less information is available about innate immune response of O. niloticus faced with hyperosmolality. Acute osmotic stress was elicited by transferring tilapia from freshwater (FW) to 24 psu seawater (SW). Non-specific immune parameters including lysozyme activities of plasma and head kidney (HK), alternative complement pathway (ACP) activity in plasma, phagocytic capacities of spleen and HK immune cells, and respiratory burst activity of immune cells in both HK and spleen were analyzed. Lysozyme activities were increased at 1 h and 30 h after transfer to SW, but decreased at 10 h after SW transfer. Conversely, ACP activity increased 10 h after SW transfer. Phagocytic capacity increased slightly at 1 h and 5 h after SW transfer, and respiratory burst activity showed an increase in superoxide release at 10 h after SW transfer. Taken together, these results indicate that the exposure of tilapia to hyperosmotic conditions has immunostimulatory effects on cellular and humoral immune reactions.

• Fisheries and Aquatic Sciences
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• 제5권4호
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• pp.258-262
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• 2002

Effects of Escherichia coli genomic DNA on the production of phagocyte activating supernatants by the head kidney leucocytes isolated from olive flounder (Paralichthys olivaceus) were investigated. Phagocyte activating activity of the supernatants was estimated by. measuring reactive oxygen species (ROS) production in target head kidney phagocytes. All supernatants from olive flounder head kidney leucocytes-stimulated with E. coli DNA induced significantly (P<0.01) higher ROS production from target pagocytes than the unstimulated control supernatant. Maximum enhancement of chemiluminescent response was observed $5.0-10.0{\mu}g\;mL^{-1}$ of bacterial DNA while the increment ability was decreased significantly (P<0.01) at the concentration of $20.0{\mu}mL^{-1}$. The results demonstrate that olive flounder head-kidney leucocytes stimulated with bacterial DNA release a soluble phagocyte activating cytokines capable of enhancing the respiratory burst activity from target phagocytes.

• 폴리머
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• 제29권3호
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• pp.282-287
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• 2005

조직공학적 장기재생에 있어서 필수적 요소인 생분해성 담체를 제조하기 위하여 새로운 방법인 얼음입자추출법을 사용하였다. 형광이 결합된 소 혈청 알부민(bovine serum albumin-fluoiescein isothiocyanate, FITC-BSA)과 락타이드-글리콜라이드 공중합체(PLGA)를 균일하게 혼합한 후에 제조된 얼음입자를 각각 다른 양을 첨가하여 다공성의 담체를 제조하였다. 모델 약물로 이용한 알부민의 방출 실험근 pH 7.4 인산염완충액을 사용하여 $37^{circ}C$, 100 rpm조건으로 항온조에서 28일 동안 수행하였다. 알부민의 방출은 형광 분광기를 통하여 FITC의 강도에 의해 결정되었으며 알부민의 방출 거동에 따른 담체의 형태학적 변화는 전자주사현미경을 이용하여 관찰하였다. 담체를 알부민이 용해된 용액에 단순히 함침시킨 방법에 비해 알부민을 함유하여 제조한 담체의 경우에 초기 방출량이 적고 일정한 방출거동을 보였다. 또한 알부민의 농도에 따른 실험에서 농도가 증가하여도 초기 방출량은 증가하지 않음을 확인할 수 있었다. 본 실험을 통해 PLGA를 이용하여 얼음입자 추출법으로 제조한 담체는 단백질 약물의 서방화가 훌륭하여 생체조직공학적 담체로서 응용 가능함을 확인하였다. 또한, 물 등께 의한 다공물질 추출 과정이 없기 때문에 사이토카인 등과 같은 수용성 인자들의 포접이 용이하여 조직공학적 바이오장기 재생에 유효할 것으로 사료된다.

• 폴리머
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• 제31권3호
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• pp.201-205
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• 2007

폴리락타이드, 폴리글리콜라이드, 및 글리콜라이드-락타이드 공중합체(PLGA)와 같은 생분해성 고분자들은 쉬운 약물방출량 조절과 부산물독성이 없이 지지체의 완벽한 분해과 좋은 생체적합성을 갖고 있다. 그러나 PLGA는 in vitro 실험에서의 괴상침식, 과도한 초기방출 후의 방출량이 감소하는 단점을 갖고 있다. 본 연구에서 PLGA 재결정 분말은 진공건조법을 이용하여 제조하였으며 1,3-bis(2-chloroethyl)-1-nitro-sourea(BCNU, carmustine)가 함유된 PLGA 웨이퍼의 방출거동을 알아보았으며 동시에 수용성 첨가제를 넣어 약물의 방출거동을 알아보고자 하였다. 진공건조법으로 재결정한 PLGA 웨이퍼가 일반방법으로 제조한 PLGA 웨이퍼보다 수분흡수율 감소와 웨이퍼 자체 초기의 분해 속도 감소로 인하여 초기 방출량이 감소하고 지속적 방출거동을 가지는 것을 확인하였다.