• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.258-263
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• 2008

The fine aggregates of below 2 mm size was fabricated using by the vertical furnace in which the aggregates could be sintered at floating state and its physical properties were analyzed. The liquid formed at the surface of specimens sintered at $1200{\sim}l300^{\circ}C$ induced a gas in core to expand so the denser shell and porous core could be produced. The C series specimen fabricated by crushing an extruded body had an irregular shape and sharp edges but those became spheroidized by bloating due to gas expansion inside. The fine aggregates fabricated in this study was as light as floating in the water and had an apparent density of $0.68{\sim}1.08$. The absorption rate was proportioned to a porosity showing that the pores in core was not closed completely. The properties of fine aggregates fabricated in vertical furnace were similar with those of in an electric muffle furnace but the sticking-together phenomenon by surface fusion was not occurred in the vertical furnace. The aggregates fabricated in this study had a little lower impact resistance than that of natural aggregate but satisfied the unit volume weight standard specified in KS.

• International Journal of Stem Cells
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• v.16 no.2
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• pp.123-134
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• 2023

Objective: The heart contains a pool of c-kit⁺ progenitor cells which is believed to be able to regenerate. The differentiation of these progenitor cells is reliant on different physiological cues. Unraveling the underlying signals to direct differentiation of progenitor cells will be beneficial in controlling progenitor cell fate. In this regard, the role of the mitochondria in mediating cardiac progenitor cell fate remains unclear. Specifically, the association between changes in mitochondrial morphology with the differentiation status of c-kit⁺ CPCs remains elusive. In this study, we investigated the relationship between mitochondrial morphology and the differentiation status of c-kit⁺ progenitor cells. Methods and Results: c-kit⁺ CPCs were isolated from 2-month-old male wild-type FVB mice. To activate differentiation, CPCs were incubated in α-minimal essential medium containing 10 nM dexamethasone for up to 7 days. To inhibit Drp1-mediated mitochondrial fragmentation, either 10 μM or 50 μM mdivi-1 was administered once at Day 0 and again at Day 2 of differentiation. To inhibit calcineurin, either 1 μM or 5 μM ciclosporin-A (CsA) was administered once at Day 0 and again at Day 2 of differentiation. Dexamethasone-induced differentiation of c-kit⁺ progenitor cells is aligned with fragmentation of the mitochondria via a calcineurin-Drp1 pathway. Pharmacologically inhibiting mitochondrial fragmentation retains the undifferentiated state of the c-kit⁺ progenitor cells. Conclusions: The findings from this study provide an alternative view of the role of mitochondrial fusion-fission in the differentiation of cardiac progenitor cells and the potential of pharmacologically manipulating the mitochondria to direct progenitor cell fate.

• Molecules and Cells
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• v.40 no.10
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• pp.706-713
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• 2017

Osteoclasts are bone-resorbing cells that are derived from hematopoietic precursor cells and require macrophage-colony stimulating factor and receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) for their survival, proliferation, differentiation, and activation. The binding of RANKL to its receptor RANK triggers osteoclast precursors to differentiate into osteoclasts. This process depends on RANKL-RANK signaling, which is temporally regulated by various adaptor proteins and kinases. Here we summarize the current understanding of the mechanisms that regulate RANK signaling during osteoclastogenesis. In the early stage, RANK signaling is mediated by recruiting adaptor molecules such as tumor necrosis factor receptorassociated factor 6 (TRAF6), which leads to the activation of mitogen-activated protein kinases (MAPKs), and the transcription factors nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and activator protein-1 (AP-1). Activated NF-${\kappa}B$ induces the nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), which is the key osteoclastogenesis regulator. In the intermediate stage of signaling, the co-stimulatory signal induces $Ca^{2+}$ oscillation via activated phospholipase $C{\gamma}2$ ($PLC{\gamma}2$) together with c-Fos/AP-1, wherein $Ca^{2+}$ signaling facilitates the robust production of NFATc1. In the late stage of osteoclastogenesis, NFATc1 translocates into the nucleus where it induces numerous osteoclast-specific target genes that are responsible for cell fusion and function.

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.490-496
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• 1998

Aspergillus oryzae producing high proteolytic enzyme was isolated from soybean koji and named tentatively A. oryzae O-1. A. oryzae U-1 was obtained by mutation of A. oryzae O-1 with ultraviolet (UV)-irradiation and produced 14 times higher pretense activity compared with A. oryzae O-1. A. oryzae E-1 was acquired by treatment of A. oryzae U-1 with 0.5 M ethylmethanesulfonate (EMS) for 6 min at 3$0^{\circ}C$ and produced 39 times higher proteolytic activity than A. oryzae O-1. With protoplast fusion between A. oryzae O-1 and A. oryzee E-1 in the presence of polyethylenegylcol (PEG)-CaCl$_2$, proteolytic activity was increased to 82 times compared to A. oryzae O-1, and the fusant was named A. oryzae PF. The activities of the cultures containing proteolytic enzymes produced by the strains were determined to be 0.23 U/$m\ell$ for A. oryzae O-1, 3.29 U/$m\ell$ for A. oryzae U-1, 8.91 U/$m\ell$ for A. oryzae E-1, and 19.0 U/$m\ell$ for A. oryzae PF.

• Journal of the Korean Ceramic Society
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• v.18 no.4
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• pp.229-236
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• 1981

This study deals with the high temperature (600-135$0^{\circ}C$) properties of Kaolin-Phosphate-Water systems. Phosphoric acid, mono aluminum phosphate, mono ammonium phosphate, the mixture of phosphoric acid and mono aluminum phosphate, and the mixture of phosphoric acid and mono ammonium phosphate were used to characterize the M.O.R of the systems with to quantity of phosphates and firing temperature. Firing shrinkage, creeptest, DTA, TGA, and X-ray diffraction patterns were also measured in order to investigate the factors of strengthening. The resules of the experiments are as follows: 1. Linear shrinkage of kaolin-phosphate systems become larger as the firing temperature rise, and generally in the firing temperature of $600^{\circ}C$ and 100$0^{\circ}C$ the test pieces with phosphate binder show larger then Kaolin-Water system in linear shrinkage and reversed trends were found at 120$0^{\circ}C$ and 135$0^{\circ}C$. 2. Cold M.O.R. of kaolin-phosphate systems show higher trends in strength as the firing temperature rise. Comparing M.O.R. of test pieces after firing at 135$0^{\circ}C$, the mixture of phosphoric acid-mono aluminum phosphate, and phosphoric acid mono ammonium phosphate systems show higher strength than kaolin-mono aluminum phosphate system which widely used, and it shows highest strength when the mole ratio of phosphoric acid and mono ammonium phosphate is 1:1 among the test pieces of kaolin-phosphate systems. 3. The refractoriness of kaolin-phosphate systems are more deteriorated than Kaolin-Water system, and generally, the more addition of phosphate, the lower the refractoriness, however in the range of 4-8% phosphate addition, the difference of the fusion temperature is about 7$0^{\circ}C$. 4. The test pieces of T1 and T2 in creep test were same or even higher than kaolin-water system when 6% of phosphoric acid-mono ammonium phosphate was added to kaolin. 5. In case where the phosphoric acid-mono ammonium phosphate was added to kaolin in mole ratio 1:1 the cold M.O.R., after firing at 135$0^{\circ}C$, refractoriness and $T_2$ in creep test show better results than kaolin-mono-aluminum phosphate system which is widely used. 6. Phosphoric acid and mono ammonium phosphate react with kaolin in temperature over 100$0^{\circ}C$, and it forms aluminum phosphate.

• Molecules and Cells
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• v.24 no.3
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• pp.316-322
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• 2007

Glutaredoxins (Grxs), also known as thioltransferases (TTases), are thiol oxidoreductases that regulate cellular redox state in a variety of organisms. In the budding yeast Saccharomyces cerevisiae, Grx1 and 2 are cytosolic dithiol Grxs, while Grx3, 4 and 5 are monothiol Grxs. A gene encoding a new monothiol Grx, Grx6, was cloned from the genomic DNA of S. cerevisiae by PCR. Its DNA sequence contains 1,080 bp, and encodes a putative protein of 203 amino acid residues containing Cys-Phe-Tyr-Ser at the active site. Grx6 is similar to other monothiol Grxs in the same organism and to Grx3 in the fission yeast Schizosaccharomyces pombe. and its predicted three-dimensional structure resembles that of S. pombe Grx3. S. pombe cells harboring plasmid pFGRX6 containing the Grx6 gene had about 1.3-fold elevated Grx activity in the exponential phase, and grew better than the control cells under some stressful conditions. Synthesis of ${\beta}$-galactosidase from a Grx6-lacZ fusion gene in S. pombe was enhanced by potassium chloride, aluminum chloride and heat ($37^{\circ}C$) treatment. S. pombe cells harboring plasmid pFGRX6 had elevated ROS levels whereas S. pombe cells harboring extra copies of Grx3 had reduced ROS levels.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.402-407
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• 2010

Introduction: The planning of implant surgery is an important factor for the implant prosthesis. Stereolithographic (SLA) surgical stents based on a computer simulation are quite helpful for clinicians to perform the surgery as planned. Although many clinical and technical trials have been performed for computed tomography (CT)-guided implant stents to improve the surgical procedures and prosthetic treatment, there are still many problems to solve. We developed a system of a surgical guide based on 3 dimensional (3D) CT for implant therapy and achieved satisfactory results in the terms of planning and operation. Materials and Methods: Fifteen patients were selected and 30 implant fixtures were installed. The preoperative CT data for surgical planning were prepared after obtaining informed consent. Surgical planning was performed using the simulation program, Ondemend3D In2Guide. The stents were fabricated based on the simulation data containing information of the residual bone, the location of the nerve, and the expected design of the prostheses. After surgery with these customized stents, the accuracy and reproducibility of implant surgery were evaluated based on the computer simulation. The data of postoperative CT were used to confirm this system using the image fusion technique and compare the implant fixtures between the planned and implanted. Results: The mean error was 1.18 (${\pm}0.73$) mm at the occlusal center, 1.23 (${\pm}0.67$) mm at the apical center, and the axis error between the two fixtures was $3.25^{\circ}C$ (${\pm}3.00$). These stents showed superior accuracy in maxilla cases. The lateral side error at the apical center was significantly different from the error at the occlusal center but there were no significant differences between the premolars, 1st molars and 2nd molars. Conclusion: SLA surgical stents based on a computer simulation have the satisfactory accuracy and are expected to be useful for accurate planning and surgery if some errors can be improved.

• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.137-141
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• 2008

We previously isolated and cloned a cDNA of abaecin from the Bombus ignitus. In an effort to produce a large amount of soluble abaecin at low cost, we successfully expressed the peptide in Escherichia coli that are highly sensitive to its mature form. For this, we fused the peptide encoding 39 amino acids of mature B. ignitus abaecin to the thioredoxin gene together with a C-terminal 6xHis tag. An enterokinase cleavage site was introduced between the 6xHis tag and mature abaecin to allow final release of the recombinant peptide. A high yield of 9.6 mg soluble fusion protein from 200 ml of bacterial culture was purified by $Ni^{2+}$-charged His-Bind resin affinity column, and 1.4 mg of pure active recombinant abaecin was readily obtained by enterokinase cleavage, followed by affinity chromatograph. The molecular mass of recombinant abaecin peptide was determined by Tricin-SDS-PAGE analysis. The recombinant abaecin exhibited antibacterial activity against Gram-negative bacteria.

• Journal of Biomedical Engineering Research
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• v.22 no.1
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• pp.69-80
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• 2001

본 연구에서는 환자의 골다공증 유무에 따른 내고정 장치 시술 직후 및 융합 후의 안정성을 평가하기 위해 다양한 하중 모드에서 C5-C6 운동분절의 생체역학적 거동을 분석하였다. 이러한 목적으로 먼저, C5-C6 경추부의 유한요소 모델을 구현하여 검증하였다. 모델의 결과는 기존 실험치와 유사하여 신뢰성이 부여되었다. 검증된 모델은 Smith-Robinson 방식으로 골이식물을 삽입한 후 전방 내고정 장치를 적용한 시술 상황을 재현하기 위해 수정되었다. 수정된 모델은 두 종류로 구현되었다. (1) 첫 번째 모델에서는, 시술 직후의 상황을 재현하기 위해 골이식물과 종판의 경계면에 접촉요소를 사용하였다. (2)두 번째 모델에서는 완전히 융합된 상황을 나타내기 위해 골이식물을 종판에 고정하였다. 골다공증의 효과를 예측하기 위하여 두 모델의 해면골에 대한 탄성계수를 변화시켰다(정상: 100MPa, 골다공증: 40MPa). 각 모델의 C5 주체의 상위면에 73.6N의 압축 하중을 가한 후에 108Nm의 굴곡/신전, 굽힘, 비틀림 하중을 가하였으며, C6 추체의 하단면은 모든 방향에 대하여 구속하였다. 전체적인 결과에 있어서 상대적 회전운동, 미끄럼운동, 골이식물 내에서의 von Mises 응력의 경우 정상 모델에 비해 골다공증 모델에서 증가함을 보였으며, 특히 시술 직후의 모델에서 비틀림 하중이 가해진 경우, 상대적 회전운동 및 미끄럼 운동이 가장 높게 예측되었다. 이는 골다공증환자에게 전방 내고정 장치를 시술한 경우 골이식물의 파단 및 유합의 실패가 비틀림 하중에서 발생할 수 있음을 나타낸다. 해면골의 von Mises 응력은 시술 직후에 골다공증 모델의 모든 하중 모드에서, 유합 후에는 굽힘 하중 외의 모든 하중에서 ultimate strength를 초과하는 것으로 나타나 골다공증 환자에게 screw의 해리가 발생할 가능성이 높은 것으로 예측되었다. 따라서 골다공증 환자에게 과도한 운동이 발생하지 않도록 하기 위해서 시술 후 세심한 주의와 halo 같은 견고한 정형술이 필요할 것으로 사료된다.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.293-302
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• 1997

Follicular oocytes of Grade I and II were collected from 2~6 mm ovarian follicles and matured in vitro (IVM) for 24 hrs in TCM-199 su, pp.emented with 35$\mu\textrm{g}$/ml FSH, 10$\mu\textrm{g}$/ml LH, and 1$\mu\textrm{g}$/ml estradiol-17$\beta$ at 39$^{\circ}C$ under 5% CO2 in air. They were fretilized in vitro (IVF) by epididymal spermatozoa capacitated with heparin for 12 hrs. The zygotes were then co-cultured in vitro with bovine oviducted epithelial cells (BOEC) for 7 to 9 days. The optimal time for IVM, the successful enucleation of IVM oocytes by micromanipulation at different oocyte ages after IVM, and the ideal culture system for IVM for effective IVF and in vitro development of IVM-IVF embryos was examined for in vitro production of nuclear recipient oocytes and nuclear donor embryos. To improve the efficiency of nuclear transplantation (NT) of IVF embryo into IVM follicular oocytes, this study evaluated the optimal electric condition and oocytes age for activation of IVM oocytes and in vitro development of NT embryos. In vitro development of NT embryos with preactivation or non-preactivation in enucleation oocytes, cell number of IVN-IVF embryos, and NT embryos wre also examined. The results obtained were as follows; 1. The most suitable enucleation time was at 24 hpm (83.3%) rather than that of 28 hpm(69.6%) and 32 hpm(50.0%). 2. There was no difference among the fusion rates of NT embryos at the voltages of 0.75, 1.0 and 1.5 kV/cm, but the in vitro development rates to morule and blastocyst were significantly (P<0.05) higher at the voltage of 0.75(12.5%) and 1.0kV/cm (12.6%) compared to 1.5kV/cm(0%). 3. No significant difference in activation rates were seen in NT embryos stimulated for 30, 60 and 120 $\mu$sec (71.7, 85.2 and 71.9%, respectively), but the in vitro development rates to morulae and blastocyst were significantly (P<0.05) higher in the oocytes stimulated for 30 $\mu$sec (11.6%) and 60 $\mu$sec(10.7%) than 120 $\mu$sec(0.0%). 4. The fusion rates (71.0 and 87.3%) and the in vitro development rates (9.1 and 12.7%) to morula and blastocyst were seen in the NT embryos stimulated at 28 and 32 hpm under the condition of 1.0 kV/ml, 60 $\mu$sec. However, at 24 hpm the fusion rates were 64.8% and the in vitro development to morula and blastocyst were not seen. 5. The fusion rates between the 8~12, 13~17 and 18~22-cell stage of IVM-IVF embryos were not significantly different. The in vitro development rates of the fused embryos to morula and blastocyst which were received from a blastomere of 8~12, 13~17 and 18~22-cell stages of IVM-IVF embryos were 14.9, 8.3 and 6.5%, respectively. 6. The in vitro development rate of the enucleated recipient oocytes with preactivation (24.2%) to morula and blastocyst was significantly (P<0.05) higher than that of non-preactivation (12.8%). 7. The cell numbers of NT blastocyst and IVM-IVF blastocyst cultured during 7~9 days were 63$\pm$11 and 119$\pm$23, and then their the mean cell cycle number were 5.98 and 6.89, respectively.