• Biomaterials and Biomechanics in Bioengineering
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• 제2권3호
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• pp.127-141
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• 2015

Silver-based systems activated by low intensity direct current continue to be investigated as an alternative antimicrobial for infection prophylaxis and treatment. However there has been limited research on the quantitative characterization of the antimicrobial efficacy of such systems. The objective of this study was to develop a semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model providing the quantitative relationship between the critical system parameters and the degree of antimicrobial efficacy. First, time-kill curves were experimentally established for a strain of Staphylococcus aureus in a nutrientrich fluid environment over 48 hours. Based on these curves, a modified PK/PD model was developed with two components: a growing silver-susceptible bacterial population and a depreciating bactericidal process. The test of goodness-of-fit showed that the model was robust and had good predictability ($R^2>0.7$). The model demonstrated that the current intensity was positively correlated to the initial killing rate and the bactericidal fatigue rate of the system while the anode surface area was negatively correlated to the fatigue rate. The model also allowed the determination of the effective range of these two parameters within which the system has significant antimicrobial efficacy. In conclusion, the modified PK/PD model successfully described bacterial growth and killing kinetics when the bacteria were exposed to the electrically activated silver-titanium implant system. This modeling approach as well as the model itself can also potentially contribute to the development of optimal design strategies for other similar antimicrobial systems.

• 인터넷정보학회논문지
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• 제20권4호
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• pp.103-111
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• 2019

인터넷 개인방송 먹방 프로그램이 유행함에 따라, 본 연구는 이를 시청하는 것이 실제 생활에 어떠한 영향을 미치는지 살펴보고자 하였다. 한국 대학생들을 대상으로 설문조사를 실시하였으며, 총 256부를 최종분석에 사용하였다. 그 결과 첫째, 대학생 응답자들의 먹방 시청동기는 시간 보내기, 식도락 추구, 정보추구, 대리충족 추구, 의사사회 상호작용 추구 순으로 나타났다. 둘째, 대리충족 추구, 식도락 추구, 시간 보내기 추구는 인터넷 먹방 프로그램 시청에 긍정적인 영향을 미치는 것으로 나타난 반면, 정보추구와 의사사회 상호작용 추구의 영향력은 나타나지 않았다. 셋째, 인터넷 먹방 프로그램 시청은 시청행복감과 비만인의 부정적 인식에 긍정적인 영향을 미치는 것으로 나타났으며, 배달음식 주문 빈도에는 영향을 미치지 않은 것으로 나타났다. 이러한 연구 결과를 바탕으로 이 연구의 함의 및 한계점, 후속 연구에 대한 제언을 논의하였다.

• Parasites, Hosts and Diseases
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• 제57권1호
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• pp.49-53
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• 2019

Contaminated liver fluke egg in the environment has led to the high prevalence of human opisthorchiasis associated with cholangiocarcinoma in Southeast Asia. To find the effective lessening methods of Opisthorchis viverrini eggs in the contaminated environment, we investigated the temperature conditions for killing of these trematode eggs in vitro. Numerous O. viverrini eggs were obtained in the proximal part of uteri of adult worms from experimental hamsters. Mature eggs with miracidium were allocated by experimental groups (2 control: positive and negative and 4 treatment: 50, 60, 70, and $80^{\circ}C$) with 0.85% saline, and treated by the experimental plan. Eggs in each experimental groups were observed under the confocal microscope after stain with Propidium Iodide (PI) to evaluate the effect of temperatures. Eggs in 70 and $80^{\circ}C$ groups were all killed after over 10 min heated. Majority of eggs in $60^{\circ}C$ (10, 15, and 30 min heated), 70 and $80^{\circ}C$ (5 min heated) groups were inactivated. However in $50^{\circ}C$ group, below half of eggs were to be killed in all time lapse (10, 15 and 30 min). In order to prevent O. viverrini infection and cholangiocarcinoma, direct treatment of sewage by heating at 70 or $80^{\circ}C$ at least 10 min is essential. Therefore, treatment of O. viverrini eggs at a high temperature is a potential method for controlling egg contamination in sewage.

• Journal of Veterinary Science
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• 제23권3호
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• pp.48.1-48.12
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• 2022

Background: The poor intracellular concentration of enrofloxacin might lead to treatment failure of cow mastitis caused by Staphylococcus aureus small colony variants (SASCVs). Objectives: In this study, enrofloxacin composite nanogels were developed to increase the intracellular therapeutic drug concentrations and enhance the efficacy of enrofloxacin against cow mastitis caused by intracellular SASCVs. Methods: Enrofloxacin composite nanogels were formulated by an electrostatic interaction between gelatin (positive charge) and sodium alginate (SA; negative charge) with the help of CaCl₂ (ionic crosslinkers) and optimized by a single factor test using the particle diameter, zeta potential (ZP), polydispersity index (PDI), loading capacity (LC), and encapsulation efficiency (EE) as indexes. The formation mechanism, structural characteristics, bioadhesion ability, cellular uptake, and the antibacterial activity of the enrofloxacin composite nanogels against intracellular SASCVs strain were studied systematically. Results: The optimized formulation was comprised of 10 mg/mL (gelatin), 5 mg/mL (SA), and 0.25 mg/mL (CaCl₂). The size, LC, EE, PDI, and ZP of the optimized enrofloxacin composite nanogels were 323.2 ± 4.3 nm, 15.4% ± 0.2%, 69.6% ± 1.3%, 0.11 ± 0.02, and -34.4 ± 0.8 mV, respectively. Transmission electron microscopy showed that the enrofloxacin composite nanogels were spherical with a smooth surface and good particle size distributions. In addition, the enrofloxacin composite nanogels could enhance the bioadhesion capacity of enrofloxacin for the SASCVs strain by adhesive studies. The minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibitory concentration, and minimum biofilm eradication concentration were 2, 4, 4, and 8 ㎍/mL, respectively. The killing rate curve had a concentration-dependent bactericidal effect as increasing drug concentrations induced swifter and more radical killing effects. Conclusions: This study provides a good tendency for developing enrofloxacin composite nanogels for treating cow mastitis caused by intracellular SASCVs and other intracellular bacterial infections.

• Animal Bioscience
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• 제36권8호
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• pp.1285-1292
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• 2023

Objective: The objective of this study was to develop a novel endolysin (PanLys.1) for the specific killing of the ruminal hyper-ammonia-producing bacterium Peptostreptococcus anaerobius (P. anaerobius). Methods: Whole genome sequences of P. anaerobius strains and related bacteriophages were collected from the National Center for Biotechnology Information database, and the candidate gene for PanLys.1 was isolated based on amino acid sequences and conserved domain database (CDD) analysis. The gene was overexpressed using a pET system in Escherichia coli BL21 (DE3). The lytic activity of PanLys.1 was evaluated under various conditions (dosage, pH, temperature, NaCl, and metal ions) to determine the optimal lytic activity conditions. Finally, the killing activity of PanLys.1 against P. anaerobius was confirmed using an in vitro rumen fermentation system. Results: CDD analysis showed that PanLys.1 has a modular design with a catalytic domain, amidase-2, at the N-terminal, and a cell wall binding domain, from the CW-7 superfamily, at the C-terminal. The lytic activity of PanLys.1 against P. anaerobius was the highest at pH 8.0 (p<0.05) and was maintained at 37℃ to 45℃, and 0 to 250 mM NaCl. The activity of PanLys.1 significantly decreased (p<0.05) after Mn²⁺ or Zn²⁺ treatment. The relative abundance of P. anaerobius did not decrease after administration PanLys.1 under in vitro rumen conditions. Conclusion: The application of PanLys.1 to modulate P. anaerobius in the rumen might not be feasible because its lytic activity was not observed in in vitro rumen system.

• The Plant Pathology Journal
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• 제40권3호
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• pp.261-271
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• 2024

Sulfur is one of the inorganic elements used by plants to develop and produce phytoalexin to resist certain diseases. This study reported a method for preparing a material for plant disease resistance. Sulfur nanoparticles (SNPs) stabilized in the chitosan-Cu²⁺ (CS-Cu²⁺) complex were synthesized by hydrolysis of Na₂S₂O₃ in an acidic medium. The obtained SNPs/CS-Cu²⁺ complex consisting of 0.32% S, 4% CS, and 0.7% Cu (w/v), contained SNPs with an average size of ~28 nm as measured by transmission electron microscopy images. The X-ray diffraction pattern of the SNPs/CS-Cu²⁺ complex showed that SNPs had orthorhombic crystal structures. Interaction between SNPs and the CS-Cu²⁺ complex was also investigated by ultraviolet-visible. Results in vitro nematicidal effect of materials against Meloidogyne incognita showed that SNPs/CS-Cu²⁺ complex was more effective in killing second-stage juveniles (J2) nematodes and inhibiting egg hatching than that of CS and CS-Cu²⁺ complex. The values of LC₅₀ in killing J2 nematodes and EC₅₀ in inhibiting egg hatching of SNPs/CS-Cu²⁺ complex were 75 and 51 mg/l, respectively. These values were lower than those of CS and the CS-Cu²⁺ complex. The test results on the nematicidal effect against M. incognita on coffee pots showed that the SNPs/CS-Cu²⁺ complex was 100% effective at a concentration of 150 mg/l. Therefore, the SNPs/CS-Cu²⁺ complex could be considered as a biochemical material with potential for agricultural applications to control root-knot nematodes.

• IMMUNE NETWORK
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• 제20권3호
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• pp.25.1-25.13
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• 2020

Acinetobacter baumannii is known for its multidrug antibiotic resistance. New approaches to treating drug-resistant bacterial infections are urgently required. Cathelicidin-related antimicrobial peptide (CRAMP) is a murine antimicrobial peptide that exerts diverse immune functions, including both direct bacterial cell killing and immunomodulatory effects. In this study, we sought to identify the role of CRAMP in the host immune response to multidrug-resistant Acinetobacter baumannii. Wild-type (WT) and CRAMP knockout mice were infected intranasally with the bacteria. CRAMP^-/- mice exhibited increased bacterial colony-forming units (CFUs) in bronchoalveolar lavage (BAL) fluid after A. baumannii infection compared to WT mice. The loss of CRAMP expression resulted in a significant decrease in the recruitment of immune cells, primarily neutrophils. The levels of IL-6 and CXCL1 were lower, whereas the levels of IL-10 were significantly higher in the BAL fluid of CRAMP^-/- mice compared to WT mice 1 day after infection. In an in vitro assay using thioglycollate-induced peritoneal neutrophils, the ability of bacterial phagocytosis and killing was impaired in CRAMP^-/- neutrophils compared to the WT cells. CRAMP was also essential for the production of cytokines and chemokines in response to A. baumannii in neutrophils. In addition, the A. baumannii-induced inhibitor of κB-α degradation and phosphorylation of p38 MAPK were impaired in CRAMP^-/- neutrophils, whereas ERK and JNK phosphorylation was upregulated. Our results indicate that CRAMP plays an important role in the host defense against pulmonary infection with A. baumannii by promoting the antibacterial activity of neutrophils and regulating the innate immune responses.

• 한국수산과학회지
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• 제26권5호
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• pp.403-408
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• 1993

횟감으로 많이 소비되고 있는 넙치를 시료로 치사 방법(즉살, 고민사, 마취사 및 전기 자극사)을 달리하여 치사시킨 후에 $5^{\circ}C$에 저장하면서 사후 조기의 생화학적 변화에 대하여 검토한 결과는 다음과 같다. 1. 치사 직후의 어육중의 ATP 함량은 고민사에서 가장 낮았고 마취사에서 가장 높았으며, 치사후 저장중의 ATP 분해 속도는 전기 자극사, 고민사,즉살, 그리고 마취사의 순서였으며 각각 11시간, 15시간, 32시간, 그리고 40시간후에 ATP가 완전히 분해되었다 또, 분해 속도 상수는 각각 $0.429h^{-1},\;0.224h^{-1},\;0.195h^{-1}$, 그리고 $0.167h^{-1}$였다. 2. IMP의 최대 축적 시간과 함량은 전기 자극사 11시간과 $6.99{\mu}mole/g$, 고민사 20시간과 $6.12{\mu}mole/g$, 즉살 31.5시간과 $6.30{\mu}mole/g$, 그리고 마취사에서 40시간과 $6.40{\mu}mole/g$으로, 전기 자극사에서 IMP 생성이 가장 빨랐으며 그 함량도 높았다. 또, 반응 속도 상수는 각각 $0.591h^{-1},\;0.248h^{-1},\;0.165h^{-1}$, 그리고 $0.161h^{-1}$였다. 3. 어육중의 유산량의 변화는 치사 직후에 즉살에서 가장 낮았으며 저장중의 최대 축적량도 가장 낮은 $38.84{\mu}mole/g$이었지만, 전기 자극사와 고민사에서는 치사 직후에 어육중의 유산 축적량이 높았으며, 저장중의 최대 축적량도 가장 높은 값을 나타내었다. 또, 반응 속도 상수는 전기 자극사 $2.256h^{-1}$, 고민사 $1.123h^{-1}$, 즉살 $0.534h^{-1}$, 그리고 마취사 $0.526h^{-1}$였다.

• Tuberculosis and Respiratory Diseases
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• 제44권1호
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• pp.162-174
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• 1997

연구배경 : HSVtk 유전자를 암세포에 이입하여 GCV에 대해 선택적으로 감수성을 증가시키는 HSVtk/GCV 유전자치료에서 bystander effect는 모든 암세포에 유전자를 이입하지 않고도 치료효과를 얻을 수 있도록 한다. 그러나 현존하는 viral vector는 유전자이입 효율이 낮아 임상적으로 치료효과를 기대하는데는 한계가 있다. 따라서 유전자의 이입효율이 높은 새로운 vector의 개발과 함께 bystander effect의 극대화를 통해 치료효과를 증가시킬 수 있는 방법 등이 요구된다. 최근 gap junction을 통한 세포간의 metablic cooperation이 bystander effect의 주요기전임이 밝혀졌고 retinoids는 gap junction을 통한 세포간의 communication을 증가시킨다고 보고되었다. 저자들은 HSVtk/GCV 유전자치료에서 bystander effect에 미치는 retinoids의 효과를 조사하였다. 방 법 : Adenovus와 retrovirus vector를 이용하여 connexin 43를 발현하는 악성중피종세포와 connexin 43를 발현하지 않는 SKHep-J 세포주에 HSVtk 유전자를 이입한 후 HSVtk 유전자가 이입된 세포와 HSVtk 유전자가 이입되지 않은 세포들을 여러가지 비율로 혼합한 mixing study를 시행하였으며 $10^{-10}M-10^{-6}M$ RA 처리 유무에 따른 bystander effect에 의한 살상효과를 비교하였다. 그리고 gap junction을 통한 세포간의 communication에 대한 retinoids의 영향을 조사하기 위해 retinoids 처리에 따른 세포간 communication을 FACS를 이용하여 double-dye transfer study로 측정하였다. 결 과 : Connexin 43를 발현하지 않는 SKHep-J 세포주에서는 RA 처리유무에 따른 bystander effect에 의한 살상효과의 차이가 없었다. 그러나 connexin 43를 발현하는 악성중피종 세포주에서는 $10^{-8}M-10^{-6}M$ RA처리시 세포간의 communication과 bystander effect가 RA를 처리하지 않은 대조군에 비해 유의하게 증가되었다. 결 론 : RA는 gap junction을 통한 세포간의 communication을 증가시켜 HSVtk/GCV 유전자치료에서 bystander effect에 의한 살상효과를 증가시켰다. 이러한 결과는 HSVtk/GCV 유전자치료의 효과를 증가시킬 수 있는 새로운 방법이 될 수 있을 것으로 생각된다.

• Parasites, Hosts and Diseases
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• 제21권1호
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• pp.21-26
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• 1983

As a series of studios on the suitability as a second intermediate host of Clcnorchis sinensis, the wormicidal effects of mucus from epidermis of Cyprinus carpio nudus were observed. The results obtained were sumlnarized as follows : On the silica gel thin layer chromatography with the greenisll yellow supernatant in acetone: benzene110:90 as carrier, seven spots were observed in iodine chamber. The spot of Rf. 0.225 value among them disclosed the strongest wormicidal effect on the cercaria, the encysted metacercaria, and the adult of C. sinensis. hfeanwhile, no seasonal variations were found in Rf. values and effect of the wormicidal fractions. The wormicidal materials in epidermal mucus of C. carpio nudes and Carassius carassius were compared in their effect, and the former was Inore effective killing substance than the latter. It seemed that C. carpio nodus could not be proper intermediate host of C. sinensis according to results of the present study, in addition to our previous observation results.