• Archives of Pharmacal Research
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• 제28권11호
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• pp.1275-1281
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• 2005

The $G_{q/11}$ protein-coupled receptors, such as muscarinic (M1 & M3) receptors, have been shown to regulate the release of a soluble amyloid precursor protein (sAPP$\alpha$) produced from $\alpha$-secretase processing. However, there is no direct evidence for the precise characteristics of G proteins, and the signaling mechanism for the regulation of $G_{q/11}$ protein-coupled receptor mediated sAPP$\alpha$ release is not clearly understood. This study examined whether the muscarinic receptor-mediated release of sAPP$\alpha$ is directly regulated by $G\alpha_{q/11}$ proteins. The HEK293 cells were transiently cotransfected with muscarinic M3 receptors and a dominant-negative minigene construct of the G protein $\alpha$ subunit. The sAPP$\alpha$ release in the media was measured using an antibody specific for sAPP. The sAPP$\alpha$ release enhancement induced by muscarinic receptor stimulation was decreased by a $G_{q/11}$ minigene construct, whereas it was not blocked by a control minigene construct (the G$\alpha$ carboxy peptide in random order, G$\alpha_{q}$R) or $G\alpha_{j}$ constructs. This indicated a direct role of the $G\alpha_{q/11}$ protein in the regulation of muscarinic M3 receptor-mediated sAPP$\alpha$ release. We also investigated whether the transactivation of the epidermal growth factor receptor (EGFR) by a muscarinic agonist could regulate the sAPP$\alpha$ release in SH-SY5Y cells. Pretreatment of a specific EGFR kinase inhibitor, tyrophostin AG1478 (250 nM), blocked the EGF-stimulated sAPP$\alpha$ release, but did not block the oxoM­stimulated sAPP$\alpha$ release. This demonstrated that the transactivation of the EGFR by muscarinic receptor activation was not involved in the muscarinic receptor-mediated sAPP$\alpha$ release.

• Archives of Pharmacal Research
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• 제19권6호
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• pp.507-513
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• 1996

Three sesquiterpene lactone compounds, two novel(1.betha.,3.betha.-dihydroxy-6.betha.,11.betha.,4.alpha.,5.alpha.,7.alpha.H -eudesm-12, 6-olide-1-O-.betha.-D-glucopyranoside, 1.betha.,3.betha.-dihydroxy-6.betha.,11.betha.,4.alpha.,5.alpha.,7.alpha.H-eudes m-12,6-olide-1-O-.betha.-D-glucopyranoside) and 1.betha.,3.betha.-dihydroxy-6.betha.,11.betha.,4.alpha.,5.alpha., 7.alpha.H-eudesm-12,6-olide were isolated from the aqueous fraction of MeOH extract of the roots from Taraxacum hallaisanensis (Compositae) employing Amberlite XAD-2, ODS-gel, silica gel and Sephadex LH-20 column chromatographics. Another known compound, (-)-epicatechin, was isolated from the aqueous fraction of the MeOH extract. The total MeOH extract also contained phytosterol and a mixture of .betha.-amyrin acetate, .alpha.-amyrin acetate and lupeol acetate. Structures of isolated compounds were elucidated by spectroscopic parameters of IR, Mass, /sup 13/C-NMR, /sup 1/H-NMR, /sup 1/H-/sup 1/H COSY, /sup 13/C-/sup 1/H COSY and HMBC.

• Fisheries and Aquatic Sciences
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• 제4권2호
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• pp.70-74
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• 2001

To examine the production of steroids with potential oocyte maturation-inducing activity in the spotted flounder, Verasper variegatus, we have incubated post-vitellogenic oocytes (0.82­0.95mm in diameters) with radiolabeled pregnenolone and $17\alpha-hydroxyprogesterone$. The resulting metabolites were analyzed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The two main metabolites (progestogens) found in both incubations co-migrated with $17\alpha-hydroxy$, $20\alpha-dihydroprogesterone$ $(17\alpha, 20\alpha OHP)$ and $17\alpha-hydroxy,\;$20\beta-dihydroprogesterone$ (17 a20{30HP). Additional chromatography by HPLC and TLC confirmed the presence of radioactive $17\alpha, 20\alpha OHP$ and a large amount of unknown metabolite. The present study did not reveal in vitro formation of $l7\alpha 20\beta OHP$. Although 1$l7\alpha 20\beta OHP$ was found in a small amount, the synthesis of this steroid suggests that it may play a role in regulating the oocyte maturation process in the spotted flounder.

• 한국세라믹학회지
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• 제25권5호
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• pp.502-508
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• 1988

The $\alpha$ to $\beta$ phase transformation of $\alpha$-Si3N4 whisker and related microstructural changes have been investigated. When only $\alpha$-Si3N4 whisker was heat treated in the range 1650~175$0^{\circ}C$, the $\alpha$ to $\beta$ phase transformation occured. In this case, it eas suggested that the oxygen content in $\alpha$-Si3N4 whisker affected the transformation behavior. Although $\alpha$-Si3N4 whisker with Si was heat treated under the same condition, however, the variation of $\beta$- fraction had a similar tendency with heat treating time. Therfore, it was considered that the oxygen content in $\alpha$-Si3N4 whisker affected the transformation behavior dominently rather than the content of added Si. The added $\beta$ phase did not affect the transformation behaviro of $\alpha$-Si3N4 whisker.

• East Asian mathematical journal
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• 제24권4호
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• pp.317-328
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• 2008

In this paper we introduce ${\pi}G{\alpha}$-LC sets, ${\pi}G{\alpha}-LC^*$ sets and ${\pi}G{\alpha}-LC^{**}$ sets and different notions of generalizations of continuous functions in topological space and discuss some of their properties. Further we prove pasting lemma for ${\pi}G{\alpha}-LC^{**}$ continuous functions and ${\pi}G{\alpha}-LC^{**}$ irresolute functions.

• 약학회지
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• 제37권1호
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• pp.49-53
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• 1993

Arylalkanoic acid derivatives are known as good non-steroidal antiinflamatory and antirheumatic agents. The new arylalkanoic acid derivatives were synthesized when 2-chloro-3-($\alpha$-cyano-$\alpha$-ethoxycarbonyl-methyl)-1, 4-naphthoquinone was reacted with some arylamines.

• Applied Biological Chemistry
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• 제36권3호
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• pp.191-196
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• 1993

본 연구는 합성기질인 $X-{\alpha}-Gal$를 이용하여 발효유 및 유제품내의 Bifidobacteria 생균수를 측정할 목적으로 하였다. 젖산균과 Bifidobacteria의 ${\alpha}-galactosidase$ specific activity를 측정한 결과 Bifidobacteria 균주에서는 높은 ${\alpha}-galactosidase$ activity를 가지고 있었으며, 그 중 Bif. longum KCTC 3215의 specific activity는 8.57 unit/mg protein으로 가장 높게 나타났다. Lactobacillus, Streptococcus, Pediococcus와 Leuconostoc 균주에서는 활성이 미약하거나 없었다. 합성기질인 $X-{\alpha}-Gal$을 MRS agar 배지에 $100{\;}{\mu}M$ 첨가한 결과 Bifidobacteria는 blue colony로, Lac. bulgaricus, Lac. casei와 Leu. mescenteroides 균주는 light blue colony로, 그 외 젖산균에서는 white colony로 나타났다.

• Applied Biological Chemistry
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• 제38권1호
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• pp.37-41
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• 1995

쥐 뇌에서 연령증가에 따른 progesterone의 대사에 대하여 연구하였다. 그 기초실험으로 생후 5일된 암컷 쥐의 뇌를 균질기로 분쇄한 경우와 잘게다진 경우의 실험에서 잘게다진 경우가 더 좋은 활성을 보였으며 쥐뇌 0.3 g, 30분의 표준 실험조건을 결정하였다. 그 결과로 $5{\alpha}$-환원요소의 경우 생후 $5{\sim}14$일에 가장 활성이 높았으며 점차적으로 감소하여 6주 이후에는 거의 일정한 활성을 나타내었다. $3{\alpha}-hydroxy$스테로이드 산화 환원요소$(3{\alpha}-HSOR)$도 $5{\alpha}$-환원요소와 비슷한 형태의 활성을 보였다. 그러나 이때 $3{\beta}-HSOR$의 활성은 연령에 따라 변화가 없이 거의 일정함을 알 수 있었다. 따라서 연령에 따른 $5{\alpha}$-환원대사산물 생성의 감소는 $5{\alpha}$-환원효소의 감소와 $3{\alpha}-HSOR$의 감소에 의하여 일어남을 알 수 있었다.

• 한국식품과학회지
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• 제22권7호
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• pp.802-804
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• 1990

${\alpha}-Cyclodextrin(CD)$이 starch-iodine 복합체를 변색시킬 수 있다는 성질을 이용하여 ${\alpha}CD$의 새로운 비색정량법을 확립하였다. 이 새로운 ${\alpha}CD$의 정량법은 다음과 같다. ${\alpha}CD$의 표준용액을 2 mg/ml까지 농도별로 준비하였다. 그리고 동량으로 혼합된 starch-iodine 복합체 용액 1ml에 ${\alpha}CD$ 표준용액 $200\;{\mu}l$와 증류수 3 ml를 함께 가하고, 570 nm에서 흡광도를 측정하였다. 이 방법으로 ${\alpha}CD$의 농도범위는 $0{\sim}2\;mg/ml$까지 측정할 수 있었고, 570 nm에서의 흡광도도 가장 좋은 직선성을 나타내었다. 한편, ${\beta}CD$와 glucose는 ${\alpha}CD$ 정량을 위한 본 방법에 아무런 방해효과가 없었다.

• 한국미생물·생명공학회지
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• 제30권4호
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• pp.332-338
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• 2002

토양으로부터 세포외로 $\alpha$-galactosidase를 분비 생산하는 방선균 YB-4가 분리되었으며, 분리균의 배양ㆍ형태ㆍ생리적 특성을 조사한 결과 Streptomyces 속 균주로 확인되었다. 분리균의 배양상등액으로부터 부분정제된 $\alpha$-galactosidase를 조효소액으로 사용하였을 때 para-nitrophenyl-$\alpha$-D-galacto-pyranoside는 pH 6.0과 6$0^{\circ}C$의 반응조건에서 가장 잘 분해되었으며, 조효소액을 pH 4.0에서 pH 10.0범위에서 1시간 이상 방치한 후에도 약 90% 이상의 $\alpha$-galactosidase 활성을 유지하였다. 또한 분리균이 생산하는 $\alpha$-galactosidase는 melibiose, raffinose와 stachyose와 같은 저당류를 가수분해 할 수 있으며 분해산물로 galactose를 방출하는 것으로 보아 $\alpha$-1,6 결합을 분해한 것으로 확인되었다.