• Korean Chemical Engineering Research
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• 제59권1호
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• pp.21-34
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• 2021

본 연구에서는 Chitosan nanoparticles (CNPs) 와 Lactococcus lactis (L. lac.) 를 흡착제로 사용하여 phthalates의 흡착 실험을 진행하였다. CNPs는 Tripolyphospate (TPP)와의 가교 결합을 통하여 제조되었으며, 제조과정 중에 L. lac.의 도입을 통하여 L. lac.-CNPs를 제조하였다. 모든 흡착제는 Fourier transform infrared spectroscopy (FTIR)을 사용하여 특성을 측정하여 다양한 작용기의 존재를 확인하였다. Adsorption isotherm 과 adsorption kinetic 을 통하여 CNPs, L. lac. 및 L. lac.-CNPs 의 흡착 거동 및 메커니즘을 확인하였다. 모든 입자에 대하여 DBP 및 DEP 의 흡착 거동은 Langmuir adsorption isotherm model 보다는 Freundlich adsorption isotherm model 에 적합하였으며, 이는 입자의 표면이 이질적 (heterogeneous) 라는 것을 의미한다. 흡착 메커니즘은 Pseudo-1st-order model 보다는 Pseudo-2nd-order model 에 적합하였으며, 이는 DBP 및 DEP 의 흡착이 입자 표면의 다양한 작용기들에 의하여 물리적 흡착보다는 정전기적 인력과 수소 결합 등에 의한 화학적 흡착이 지배적임을 나타낸다. 최종적으로, 쉽고 빠른 방법으로 CNPs 및 L. lac-CNPs 의 제조가 가능하며, 유기성 오염 물질을 효과적으로 제거할 수 있는 저비용의 흡착제로서 사용할 수 있음을 확인하였다.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2000년도 국제심포지움 및 추계학술대회
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• pp.45-67
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• 2000

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a mutagenic and carcinogenic heterocyclic amino found in cooked meat. The in vivo mutagenicity and hepatocarcinogenicity of MeIQx were examined in mice harboring the lacZ mutation reporter gene ($Muta^{TM}$ Mice) and bitransgenic mice over-expressing the c-myc oncogene. C57B1/$\lambda$lacZ and bitransgenic c-myc (albumin promoter)/$\lambda$lacZ mice were bred and weaned onto an AIN-76 based diet containing $0.06\%$ (w/w) MeIQx or onto control diet. After 30 weeks on diet, only male bitransgenic mice on MeIQx developed hepatocellular carcinoma ($100\%$ incidence) indicating that there was synergism between c-myc over-expression and MeIQx. By 40 weeks, hepatic tumor incidence was $100\%$ ($17\%$) and $44\%$ ($0\%$) in male c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice given MeIQx (or control) diet, respectively, indicating that either MeIQx or c-myc over-expression alone eventually induced hepatic tumors. At either time point, mutant frequency in the lacZ gene was at least 40-fold higher in MeIQx-treated mice than in control mice of either strain. These findings suggest that MeIQx-induced hepatocarcinogenesis is associated with MeIQx-induced mutations. Elevated mutant frequency in MeIQx-treated mice also occurred concomitant with the formation of MeIQx-guanine adducts as detected by the $^{32}P$-postlabeling assay. Irrespective of strain or diet, sequence analysis of the lacZ mutants from male mouse liver showed that the principal sequence alteration was a single guanine-base substitution. Adenine mutations, however, were detected only in animals on control diet. MeIQx-fed mice harboring the c-myc oncogene showed a l.4-2.6-fold higher mutant frequency in the lacZ gene than mice not carrying the transgene. Although there was a trend toward higher adduct levels in c-myc mice, MeIQx-DNA adduct levels were not significantly different between c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice after 30 weeks on diet. Thus, it appeared that factors in addition to MeIQx-DNA adduct levels, such as the enhance rate of proliferation associated with c-myc over-expression, may have accounted for a higher mutant frequency in c-myc mice. In the control diet groups, the lacZ mutant frequency was significantly higher in c-myc/$\lambda$lacZ mice than in 057B1/$\lambda$1acZ mice. The findings are consistent with the notion that c-myc over-expression is associated with an increase in mutagenesis. The mechanism for the synergistic effects of c-myc over-expression on MeIQx hepatocarcinogenicity appears to involve an enhancement of MeIQx-induced mutations.

• 미생물학회지
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• 제30권6호
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• pp.460-465
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• 1992

The effect of PSOD expression on lacZ-sodP fusion (pYK4) was explored in Escherichia coli sodA sodB mutants (QC774) under oxidative stress. In this system, although .betha.-galactosidase activity was not fully induced by isopropyl-1-thio-.betha.-galactosidase (IPTG) and was inhibited by glucose, functional PSOD was under lacZ promotor control and was induced by IPTC, lactose, PQ and copper isons, finally, the results show that higher PSOD expression leel was consistently importnat in defending against superoxide radicals.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1233-1236
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• 2003

This paper proposes a phase-locked loop (PLL) that achieves one-cycle lock acquisition by employing the lock-acquisition circuit (LAC). The LAC produces the initial analog voltage ( v$_{c}$ ) that corresponds to the input frequency. When the transfer curve of the LAC matches that of the voltage-controlled oscillator (VCO), one-cycle locking can be possible. By HSPICE simulations, the proposed LAC is proved to be applicable to any kinds of PLL [1][2][3].].

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.2046-2055
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• 2007

Wild-type V. vulnificus cannot grow using lactose as the sole carbon source or take up the sugar. However, prolonged culture of this species in media containing lactose as the sole carbon source leads to the generation of a spontaneous lactose-utilizing (LU) mutant. This mutant showed strong ${\beta}$-galactosidase activity, whereas the wild-type strain showed a barely detectable level of the activity. A mutant with a lesion in a gene homologous to the lacZ of E. coli in the bacterium no longer showed ${\beta}$-galactosidase activity or generated spontaneous LU mutants, suggesting that the lacZ homolog is responsible for the catabolism of lactose, but the expression of the gene and genes for transport of lactose is tightly regulated. Genetic analysis of spontaneous LU mutants showed that all the mutations occur in a lacI homolog, which is located downstream to the lacZ and putative ABC-type lac permease genes. Consistent with this, a genomic library clone containing the lad gene, when present in trans, made the spontaneous LU mutants no longer able to utilize lactose as the sole carbon source. Taken together with the observation that excessive amounts of exogenously supplemented possible catabolic products of lactose have negative effects on the growth and survivability of V. vulnificus, we suggest that V. vulnificus has evolved to carry a repressor that tightly regulates the expression of lacZ to keep the intracellular toxic catabolic intermediates at a sublethal level.

• 미생물학회지
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• 제27권3호
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• pp.201-209
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• 1989

Mu dJ(km lac) peron 융합을 이용하여 Salmonella typhimurium에서 산소에 의해 조절되는 여러개의 새로운 유전자좌를 확인하였다. 산소가 있는 조건에서 유도된 9개의 유전자와 무산소조건에서 유도된 13개의 유전자가 분리되었다. 유전자 융합체들은 조절윤전자 oxrA의 control에 근거하여 2classe로 구분되었는데, class I 유전자들은 ozrA에 의해 조절되고, class II 유전자들은이 조절 유전자에 의해 영향을 받지 않았다. 몇몇 anti-lacZ 유전자 융합체들으 최소배지에서 발현되지 않았고, LB상에서나 혹은 CAA 첨가배지에서 그 활성을 나타내었다. 대부분의 유전자 융합체들은 nitrate와 fumarate에서 발현이 억제되었다. ani 유전자 가운데 3개의 유전자는 상호형질도입 빈도에 의해 각각 $59{\pm}0.14$ map unit (YK114), $64{\pm}0.2$ map unit(YK120), and $93{\pm}0.29$ map unit(YK112) 로 결정되었다.

• Investigative Magnetic Resonance Imaging
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• 제8권2호
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• pp.86-93
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• 2004

목적 : 수소 자기공명분광법이 미만성 침습성 양상의 일차성 중추신경 림프종의 감별진단에 도움을 주는가에 대하여 알아보고자 하였다. 대상 및 방법 : 정위적 생검에 의해 확진된 7명의 일차성 중추신경 림프종 환자의 수술 전 임상양상 및 자기공명영상을 알아보았으며, 수소 자기공명분광법의 소견을 후향적으로 조사하였다. 정량 분석을 위하여, 자기공명분광법의 스펙트럼에서 Choline(Cho), N-acetyl aspartate (NAA), 그리고 lipid-lactate(Lip-Lac)의 creatine (Cr)에 대한 상대적인 값을 구하였다. 결과 : Cho/Cr의 평균은 $1.80{\pm}0.95$, NAA/Cr의 평균은 $1.34{\pm}0.41$, Lip-Lac/Cr은 $1.12{\pm}0.16$였다. 전례에서 Lip-Lac/Cr의 통계학적으로 유의한 증가 소견을 보였다. 7예 중 2예의 종괴를 형성하는 경우 NAA/Cr 의 유의한 감소를 보였지만 종괴형성이 분명하지 않은 경우 NAA/Cr의 감소는 없었다. 결론 : 수소자기공명분광법에서 Lip-Lac 피크 출현에도 불구하고 NAA 피크의 현저한 감소가 동반되지 않는 소견은 종괴를 형성하지 않는 미만성 침습성 림프종을 진단하는데 도움을 주는 소견으로 생각된다.

• 미생물학회지
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• 제23권1호
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• pp.20-24
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• 1985

Klebsiella pnellmoniae의 nif-lac융합변이주를 사용하여 질소고정 유전자 발현에 미치는 질소원의 효과를 검토하였다. Klebsiella pnellmoniae UN4482를 heat induction하여 만든 Mudllysate를 K. pnellmoniae U UN2979에 접종시켜 nif-lac융합체 약 80여주를 분리하고 이들을 LX series로 명하였다. 이들의 ${\beta}-galactosidase$ 한성은 $NH_4^+$의 존재하에 크게 억제되었다. Serine, glutamine, asparagine같은 아미노산을 켈소원으로 사용했을때 K. pnellmoniae의 성장은 양호하였으며. NFHM배지에서nif-lac융합주LX-9, LX-22의 ${\beta}-galactosidase$의 환성은 억제 효과도 높았으나, glutamine, histidine, arginine 같은 amino acid는 위와 반대 의 효과플 나타냈다. Casitone, prote-ose peptone같은 유기섣소원(2 mg/ml )의 균성장에 대한효과는 전반적으로양호했으나LX-9, LX-22 의 ${\beta}-galactosidase$활성에 대한 억제효과는 각 칠소원에 따라 다르게 나타났다. 한편, 질소원이 없는 최소배지에서의 LX-9와 L LX-22의 ${\beta}-galactosidase$의 활성은 초기 4 시간내에 급격히 증가하였다.

• 한국자기공명학회논문지
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• 제13권2호
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• pp.64-83
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• 2009

The purpose of this study was to evaluate the usefulness of in vivo 3T $^1H$ MRS with short TE for prescreening various brain diseases. Together with ten normal volunteers, 12 brain tumor patients(2 lymphomas, 5 malignant gliomas) and 5(benign meningiomas) and 10 brain ischemic disease patients(6 acute and 4 subacute infarctions) participated. Lymphomas showed increased intensities of Cho and Lac. Likewise, gliomas showed increased Cho and Lac, but with decreased NAA and ${\beta}\;{\gamma}$-Glx; in higher grade of gliomas, Lac, Cho, mI and Lip predominantly increased with decrease of NAA. Benign meningiomas showed increased Cho, Lac and ${\beta}\;{\gamma}$-Glx; with decreased of NAA. The alanine peak at 1.47 ppm is a neuronal marker for meningiomas. Infarctions showed increased Lac and Lip and decreased NAA, ${\alpha}$-Glx and ${\beta}\;{\gamma}$-Glx where Lac increased with decreased of ${\alpha}$-Glx in acute, and Cho, Lac and Lip increased with decrease of NAA in subacute. Elevated Lac and decreased NAA levels were more aggravated in subacute. Clinical application of the $^1H$ MRS with short TE at 3T is able to povide valuable spectral information for prescreening various brain diseases by monitoring the changes of disease-specific cerebral metabolite concentrations in vivo, and consequently, it can be applicable to assessment of differential diagnosis and malignancy as well.

• Journal of Microbiology
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• 제44권6호
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• pp.617-621
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• 2006

Coprinellus congregatus secreted a laccase isozyme when the culture was transferred to an acidic liquid medium (pH 4.1). The laccase cDNA gene (clac2) was used as a probe for cloning of the genomic laccase gene (lac2) including the promoter (Plac2). The open reading frame (ORF) of lac2 had 526 deduced amino acids and four conserved copper binding domains as other fungal laccases. Recombinant plasmid (pRSlac2p-cDNA) of lac2 cDNA with its own promoter was transformed in Saccharomyces cerevisiae. Expression of the transformed lac2 gene was induced by oxidative stress ($H_2O_2$) in yeast and the survival rate of the transformed yeast strain was greatly increased when compared with that of the control strain transformed with pRS316 yeast vector.