• Korean Journal of Materials Research
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• v.26 no.8
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• pp.449-453
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• 2016

$HA(hydroxyapatite)/{\beta}-TCP$ (tricalcium phosphate) biomaterial (BCP; biphasic calcium phosphate) is widely used as bone cement or scaffolds material due to its superior biocompatibility. Furthermore, $NH_4HCO_3$ as a space holder (SH) has been used to evaluate feasibility assessment of porous structured BCP as bone scaffolds. In this study, using a spark plasma sintering (SPS) process at 393K and 1373K under 20MPa load, porous $HA/{\beta}-TCP$ biomaterials were successfully fabricated using $HA/{\beta}-TCP$ powders with 10~30 wt% SH, TiH2 as a foaming agent, and MgO powder as a binder. The effect of SH content on the pore size and distribution of the BCP biomaterial was observed by scanning electron microscopy (SEM) and a microfocus X-ray computer tomography system (SMX-225CT). The microstructure observations revealed that the volume fraction of the pores increased with increasing SH content and that rough pores were successfully fabricated by adding SH. Accordingly, the cell viabilities of BCP biomaterials were improved with increasing SH content. And, good biological properties were shown after assessment using Hanks balanced salt solution (HBSS).

• Journal of Periodontal and Implant Science
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• v.42 no.4
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• pp.136-143
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• 2012

Purpose: The osseointegration around titanium mini-implants installed in macroporous biphasic calcium phosphate (MBCP) blocks was evaluated after incubation with recombinant human bone morphogenetic protein-2 (rhBMP-2) in an ectopic subcutaneous rat model. Methods: Mini-implants (${\varphi}1.8{\times}12$ mm) were installed in MBCP blocks (bMBCPs, $4{\times}5{\times}15$ mm) loaded with rhBMP-2 at 0.1 mg/mL, and then implanted for 8 weeks into subcutaneous pockets of male Sprague-Dawley rats (n=10). A histomorphometric analysis was performed, and the bone-to-implant contact (BIC) and bone density were evaluated. Results: Significant osteoinductive activity was induced in the rhBMP-2/bMBCP group. The percentage of BIC was $41.23{\pm}4.13%$ (mean${\pm}$standard deviation), while bone density was $33.47{\pm}5.73%$. In contrast, no bone formation was observed in the bMBCP only group. Conclusions: This model represents a more standardized tool for analyzing osseointegration and bone healing along the implant surface and in bMBCPs that excludes various healing factors derived from selected animals and defect models.

• 한국해양학회지
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• v.28 no.4
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• pp.323-331
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• 1993

The concentration-dependence of and the effect of light on urea decomposition, and the suppression of urea decomposition by ammonium were studied to understand adaptations in phytoplankton to utilization of urea in the estuarine system of the Mankyung and Dongjin rivers and a hypertrophied pond. Results of size-fractionation showed that bacterial fraction played a minor role (14%) in urea decomposition in the estuary. However, the role of bacteria in urea decomposition seemed to increase in a hypertrophic pond. Natural phytoplankton communities exhibited a monophonic or biphasic kinetics of urea decomposition over a wide range of concentration (upto 7.7 mM). the addition of high concentration of ammonium and incubation of the euphotic samples in the dark caused reductions in the urea decomposition rates. It is suggested that understanding of adaptations in phytoplankton to urea decomposition would help to study the temporal and spatial variabilities of urea decomposition rates in the field and the significance of urea in nitrogen cycle.

• Journal of Acupuncture Research
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• v.18 no.1
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• pp.76-87
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• 2001

Objective : Zusanli(ST36) and Hoku(Li4) are analgesic acupuncture points frequently used for acupuncture in Oriental medicine. The present study was conducted to see the antinociceptive effects produced by electroacupuncture combined two frequencies(Low, High) and two different acupuncture points(LI4, ST36) in the rat tail flick test. Method : In this study the Rats (Sprague-Dawley, 250-300g) were partially anesthetized with thiopental sodium(40mg/kg, i.p.). The basal reaction time for the tail-flick was 3${\pm}$0.5 sec. Low frequency(3Hz, 5V, biphasic) and high frequency(100Hz, 5V, biphasic) were applied to the inserted needle for the period of insertion(twenty minutes). Experimental groups are divied as follow; a) electroacupuncture stimulation groups at Hoku with or high frequency(L-EA, H-EA), b) electroacupuncture stimulation groups at Zusanli with low or high frequency(1-EA, h-EA), c) low frequency at Hoku and Zusanli(LIEA), d) low frequency at Hoku and high frequency at Zusanli(LhEA), e) high frequency at Hoku and low frequency at Zusanli(HIEA), f) high frequency at Hoku and Zusanli(HhEA) Results : The individual stimulation at either Hoku or Zusanli with low frequency has stronger and longer analgesic effect than high frequency stimulation. In addition, the combined stimulation at Hoku and Zusanli with low frequency has superior effect to individual stimulation with low frequency. LhEA and LIEA have superior effect to other stimulation groups among the combined groups. In order to determine the involvement of opioid system on the different antinociceptive effects, Naloxone, an opioid antagonist, was used in the combined groups. LIEA is the most sensitive when naloxone was administrated among study groups. HhEA is the least sensitive in the administration of naloxone. Conclusion : From results, this study confirmed that the opioid system is involved in analgesic effect of low frequency stimulation of acupuncture point, and we also can suggest the stronger analgesic effect of combining stimulation points is due to the theory of spatial summation in the nervous system.

• Journal of Korean Neurosurgical Society
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• v.59 no.3
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• pp.302-305
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• 2016

Gliofibroma is an extremely rare biphasic tumor with an astrocytic and benign mesenchymal component, which commonly occurs within the first two decades of life. The exact biological behavior of the tumor is not fully understood. Therefore, it is not listed as a distinct entity in the current World Health Organization classification of central nervous system tumors. Here, we describe a rare case of gliofibroma, which was located on the medial temporal lobe in a 61-year-old woman. Preoperatively, we misdiagnosed it as a meningioma because it was a well-demarcated and well-enhanced extra-axial mass with calcification and bony destruction. On the histopathological and immunohistochemical examination, the tumor consisted of a mixture of glial tissue and mesenchymal tissue and it was finally diagnosed as a gliofibroma. To our knowledge, this case of intracranial gliofibroma is in the oldest patient ever reported.

• Journal of the Korean Applied Science and Technology
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• v.10 no.1
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• pp.9-22
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• 1993

Recent studies on enzyme reactions in organic solvents are revived. The reactions are classified into three categories: heterogeneous, biphasic and homogeneous systems. The following subjects are described and discussed about the heterogeneous system. 1) The maximal expression of enzyme activity in organic solvents in terms of water content, hydration of enzyme, and equilibriun of water between enzyme and substrate solution. 2) Solvent effect on the catalytic power of enzyme. 3) Thermostability and thermoreactivity. 4) Applications of the enzyme reactions to synthetic chemistry.

• 대한치주과학회:학술대회논문집
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• 2007.11a
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• pp.135-135
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• 2007

• Textile Coloration and Finishing
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• v.8 no.4
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• pp.4-10
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• 1996

Poly(4-morphonylphosphonate of bisphenol A) (PMPB) was synthesized by the interfacial polymerization of phosphonic dichloride, 4-morphonyl (PDCM) and bisphenol A in an aqueous-organic biphasic system. Synthesized polymer was found to be PMPB by using EA, FT-IR and $^{1}$H-NMR. Prepared PMPB had different values of molecular weight depending on the solubility in the organic phase: the higher the solubility, the higher the molecular weight. PMPB is amorphous and its thermal decomposition temperature is about 35$0^{\circ}C$. PMPB is congenial to application to polypropylene by blending because of no reaction with polypropylene.

• Macromolecular Research
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• v.17 no.7
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• pp.464-468
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• 2009

Gelatin nanoparticles derived from bovine or porcine have been developed as various types of drug delivery system, and they need to be cross-linked to maintain their physicochemical properties in aqueous environments. Although gelatin is a widely used material in pharmaceutical industries, the safety issue of animal-origin gelatins, such as transmissible mad cow disease and anaphylaxis, remains to be solved. The purpose of this study was to prepare type A gelatin (GA) nanoparticles by modified, two-step, desolvation method and compare the toxicity of the resulting GA nanoparticles with recombinant human gelatin (rHG) nanoparticles. The GA nanoparticles were characterized, and drug loading and release pattern were measured. FITC-BSA, a model protein, was efficiently loaded in the nanoparticles and then released in a biphasic and sustained release pattern without an initial burst. In particular, the cell viability of the GA nanoparticles was less than that of the rHG nanoparticles. This finding suggests that rHG nanoparticles should be considered as an alternative to animal-origin gelatin nanoparticles in order to minimize the safety problems.

• Korean Journal of Pharmacognosy
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• v.19 no.1
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• pp.19-27
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• 1988

The hexane and ether extracts from the roots of Angelica dahurica caused a significant inhibition of hepatic drug-metabolizing enzyme (DME) activity. Through systematic fractionation by $SiO_2\;column$ and vacuum liquid chromatography monitoring by bioassays, three furanocoumarins, phellopterin, byakangelicin and tert-O-methylbyakangelicin were isolated as active principles. These components have biphasic responses, both inhibitory and inducing effects on DME system. Tert-O-methyl byakangelicin was found to have the strongest enzyme inhibitory potency.