• Biomolecules & Therapeutics
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• 제19권2호
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• pp.174-180
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• 2011

Experiments were carried out to determine the role of Raf-1 kinase in the development of drug resistance to paclitaxel in v-H-ras transformed NIH 3T3 fibroblasts (Ras-NIH 3T3). We established a multidrug-resistant cell line (Ras-NIH 3T3/Mdr) from Ras-NIH 3T3 cells by stepwise increases in paclitaxel. Drug sensitivity assays indicated that the $IC_{50}$ value for drug-resistant Ras-NIH 3T3/Mdr cells was more than 1 ${\mu}M$ paclitaxel, 10- or more-fold higher than for the parental Ras-NIH 3T3 cells. Western blot and RT-PCR analysis showed that the drug efflux pump a P-glycoprotein were highly expressed in Ras-NIH 3T3/Mdr cells, while not being detectable in Ras-NIH 3T3 cells. Additionally, verapamil, which appears to inhibit drug efflux by acting as a substrate for P-glycoprotein, completely reversed resistance to paclitaxel in Ras-NIH 3T3/Mdr cell line, indicating that resistance to paclitaxel is associated with overexpression of the multidrug resistance gene. Interestingly, Ras-NIH 3T3/Mdr cells have higher basal Raf-1 activity compared to Ras-NIH 3T3 cells. Unexpectedly, however, the colocalization of Raf-1 and its negative regulator Spry2 was less observed in cytoplasm of Ras-NIH 3T3/Mdr cells due to translocation of Spry2 around the nucleus in the perinuclear zone, implying that Raf-1 may be released from negative feedback inhibition by interacting with Spry2. We also showed that shRNA-mediated knockdown of Raf-1 caused a moderate increase in cell susceptibility to paclitaxel. Thus, the results presented here suggest that a Raf-1-dependent pathway plays an important role in the development of acquired drug-resistance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.253-256
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• 2002

A programmable CMOS negative resistor has been designed and fabricated in a 0.5um double poly double metal technology. The proposed CMOS negative resistor consists of a positive feedback OTA and a bump circuit with Gaussian-like I-V curve. Measurements of the fabricated chip confirm that the proposed CMOS resistor shows various negative resistance according to control voltage.

• 대한의생명과학회지
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• 제5권1호
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• pp.17-26
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• 1999

Mar (multiple-antibiotic-resistance) 대장균의 marRAB 돌연변이가 그람음성 세균들 사이로 전파 될수 있는지를 알아보기 위해서, 염색체 위의 marRAB 돌연변이를 $\lambda$placMu9 (Km$^{r}$)를 이용하여 대장균의 다른 균주내의 pUC19 (Lac$^{+}$, Ap$^{r}$)의 클로닝 사이트, S. typhimurium 및 P. aeruginosa의 염색체 위로 각각 전달시킨 후, Mar phenotype, Km$^{r}$, Lac$^{-}$, 혹은 Ap$^{r}$ 균주를 선택한 다음, salicylate (SAL)의 유도 (induction) 유무에 따른 항생제 내성검사를 실시하였다. pUC19의 보유 유무에 관계없이 대조군인 야생형 대장균 JM109, NM522에 비해서, pUC19::marRAB 돌연변이를 가진 JM109 혹은 NM522의 대부분 균주들은 항생제 내성 수준들이 훨씬 더 높았으며, Mar표현형의 유도도 SAL에 의해서 훨씬 더 높게 나타났다. 하지만 일부 소수의 항생제에 대해서는 예외적으로 내성 수준이 더 낮게 나타났는데, 야생형 JM109 균주에서는 chloramphenicol (Cm)과 tetracycline (Tc)이 , pUC19::marRAB 돌연변이를 가진 NM522 균주 에서는 Tc와 ciprofloxacin (Cp)에 대한 내성 수준이 각각 더 낮게 나타났다. S. typhimurium 및 P. aeruginosa에 대한 같은 실험의 결과도 야생형 대장균의 경우와 거의 대부분 일치하였다. 형질전환 (transformation)과 형질도입 (transduction)의 방법을 주로 사용한 이 실험의 결과는, marRAB 돌연변이가 그람음성 세균들 사이로 전파될 수 있음을 간접적으로 암시한다.

• 한국전자파학회논문지
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• 제17권12호
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• pp.1143-1149
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• 2006

마이크로스트립 개방형 루프 공진기는 발진기의 위상 잡음을 줄이기 위해서 적용되었다. 마이크로스트립 스퀘어 개방형 루프 공진기는 큰 결합 계수 값을 가지고, 이로 인해 높은 Q 값을 가지며 전압 제어 발진기의 위상잡음을 감소시킨다. 전압 제어 발진기의 주파수 조절 범위를 증가시키기 위하여 버랙터 다이오드가 전압 제어발진기의 조절 가능한 부성 저항에 연결되어졌다. 전압 제어 발진기의 출력 파워와 하모닉 특성은 각각 4.83dBm과 -28.83 dBc이다. 위상 잡음 특성은 주파수 조절 범위 $5.735{\sim}5.845GHz$에서 $-112.33{\sim}-116.16dBc/Hz$ @ 100 kHz이다.

• 폴리머
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• 제26권3호
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• pp.367-374
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• 2002

본 연구에서는 나노 입자의 카본블랙을 결정성 고분자에 분산시켜 특정한 온도에서 저항이 급격하게 증가하는 positive temperature coefficient resistance (PTCR) 특성을 연구하였다. 열가소성 수지를 이용한 PTCR 소재를 열처리에 의하여 고분자의 큐리온도를 조절할 수 있었다. 나노입자 카본블랙이 고분자 구조내에 고르게 분산이 되지 않고, 카본블랙의 함량이 과다하면 negative temperature coefficient resistance (NTCR) 현상이 발생하였다. 카본블랙의 함량과 내부전압을 조절함에 따라 발열 온도를 선정할 수 있었다. 카본블랙의 함량에 따라 전기 전도성이 다르게 나타났으며, 20 wt% 이상에서는 저항이 거의 일정하게 나타난다는 것을 확인하였다. 본 연구에서 제조된 PTCR 소재는 반복적인 가열 냉각에 따른 상온에서의 초기 저항의 변화가 거의 없어 재현성을 확인하였으며, 초기의 낮은 저항에 의한 순간적인 발열에 의하여 저온에서의 PTCR 성능이 향상되었다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5463-5467
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• 2012

Hepatitis B virus (HBV) infection is contagious with transmissiobn vertically or horizontally by blood products and body secretions. Over 50% of Iranian carriers contracted the infection prenatally, making this the most likely route of transmission of HBV in Iran. To evaluate the resistance to adefovir (ADV) therapy in patients with chronic hepatitis B infection, a study was conducted on 70 patients (63 males and 7 females), who had received in first line lamivudine and second line adefovir. All were tested for the presence of hepatitis B surface antigen (HBsAg), hepatitis B envelope antigen (HBeAg), serum alanine amino transferase (ALT) level and HBV DNA load before and after treatment with ADV. In all samples, resistance to lamivudine and ADV was tested with real time PCR. Among seventy patients with chronic hepatitis B infection, 18 (25.7%) were resistant to LAM and 8 (11.4%) were resistant to ADV. Only one patient was negative for the presence of HBS-Ag (5.6%) and two were negative for HBe-Ag (11.1%). In this study we used a new method (ALLGIO probe assay) that has high sensitivity in detection of adefovir resistance mutants, which we recommend to other researchers. Mutant strains of the YMDD motif of HBV polymerase can be found in some patients under treatment with lamivudine and ADV. ADV has been demonstrated to be efficient in patients with lamivudine resistant HBV.

• 대한전자공학회논문지
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• 제10권1호
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• pp.9-17
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• 1973

본논문온 전류안정부저항특성을 나타내는 회로를 구성하는데 있어서, 입력전류가 변하는 어느 구간에서 입력전류의 변화에 따라서, SAMUEL SEELY가 제시한 Beam저항을 도입하여, Beam저항이 감소하는 원리를 적용하였다. 이러한 원리에 따르는 회로의 모델을 트랜지스터 회로로써 구체화하였다. 구체화된 트런지스터회로는 PNP 트런지스터와 NPN트랜지스터와 저항으로 이루어졌다. 이 회로의 전압-전류특성이 안정되도록 하기 위하여 회로를 수정하여 회로의 동작을 추정하여 해석하였다. 추정된 동작과 부저항치를 실험을 통하여 모두 뒷밭침 하였다. 여기서 얻어진 회로은 쟈이레이터의 구성과 SCR동작의 모의화등에 유용하게 이용될 것이며, 전류안정중저항회로의 구성에 관한 평이화를 기하였다.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.367-373
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• 2021

The antimicrobial resistance of Staphylococcus spp. and Gram negative strains present in air samples from waste sorting facilities was assessed. Phenotypic studies have revealed a high percentage of strains of Staphylococcus spp. resistant to methicillin. Genotypically and by RT-PCR, it was found that the mecA gene usually associated with methicillin resistance was present in 8% of the Staphylococcus strains isolated. About 30% of the Gram negative strains from the same samples also displayed resistance to meropenem and 79% of these were resistant to multiple antibiotics from different classes, namely cephalosporins and β-lactams. The results suggest that in professional activities with high levels of exposure to biological agents, the quantification and identification of the microbial flora in the work environment, with the determination of the presence of potential agents displaying multi-resistances is of relevance to the risk assessment. The personal protection of workers is particularly important relevance in these cases, since many of the strains that exhibit multi-resistance are potential opportunistic agents.

• 유통과학연구
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• 제20권3호
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• pp.95-106
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• 2022

Purpose: This study aims to verify the effects of omnichannel characteristics on pleasure, resistance and repurchase intention in the omnichannel situation in order to provide the innovative commercial business. Research design, data and methodology: The study examined relations between research concepts centered on previous studies, set hypotheses, developed a research model, and verified the model through a questionnaire survey. A total of 297 questionnaires were used for the final analysis, excluding the questionnaires showing insincere or outliers. Results: First, Omnichannel showed multi-dimensional characteristics consisting of consistency, innovation, economy, and integration. Second, innovation and economic feasibility had a positive effect on pleasure. Third, only economic feasibility had a negative effect on user resistance. Fourth, consumers' shopping pleasure had a negative effect on user resistance. Fifth, repurchase intention of consumers was positively affected by innovation. Conclusions: This research contributed to extend academic framework of distribution research by examining causal relationship through adoption of economic and innovation factors as new characteristics from the integrated perspective beyond the research frame of the existing omnichannel distribution environment. Companies should provide meaningful experiences by resolving concerns about side effects caused by human-computer interaction and providing smart information that matches the products most suitable for consumer needs.

• Journal of Microbiology and Biotechnology
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• 제20권10호
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• pp.1446-1449
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• 2010

A total of 1,444 coagulase-negative staphylococci (CNS) isolates from bovine mastitic milk samples collected during 2003-2008 in Korea were identified to the species level. Of 14 species identified, S. simulans, S. haemolyticus, and S. sciuri accounted for over 60% of the isolates. All the CNS isolates were tested for susceptibility to eight antimicrobials commonly used in dairy cattle. With a few exceptions, similar resistance patterns were observed among the CNS species: penicillin and ampicillin showed the lowest activity, whereas amikacin, cephalothin, and gentamicin were highly effective. About 39% (557/1,444) of the CNS isolates were pan-susceptible, whereas 12% (175/1,444) showed resistance to four or more antimicrobials tested.