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Xiao-Quan Xu,Sheng Liu,Qing-Quan Zu,Lin-Bo Zhao,Jin-Guo Xia,Chun-Gao Zhou,Wei-Zhong Zhou,Hai-Bin Shi 대한신경과학회 2013 Journal of Clinical Neurology Vol.9 No.2
Background and Purpose This study evaluated the clinical value of detachable-balloon embolization for traumatic carotid-cavernous fistula (TCCF), focusing on the frequency, risk factors, and retreatment of recurrence. Methods Fifty-eight patients with TCCF underwent transarterial detachable-balloon embolization between October 2004 and March 2011. The clinical follow-up was performed every 3months until up to 3 years postprocedure. Each patient was placed in either the recurrence group or the nonrecurrence group according to whether a recurrence developed after the first procedure. The relevant factors including gender, fistula location, interval between trauma and the interventional procedure, blood flow in the carotid-cavernous fistula, number of balloons, and whether the internal carotid artery (ICA) was sacrificed were evaluated. Results All 58 TCCFs were successfully treated with transarterial balloon embolization, including 7 patients with ICA sacrifice. Recurrent fistulas occurred in seven patients during the follow-up period. Univariate analysis indicated that the interval between trauma and the interventional procedure (p=0.006) might be the main factor related to the recurrence of TCCF. The second treatments involved ICA sacrifice in two patients, fistula embolization with balloons in four patients, and placement of a covered stent in one patient. Conclusions Detachable balloons can still serve as the first-line treatment for TCCFs and recurrent TCCFs despite having a nonnegligible recurrence rate. Shortening the interval between trauma and the interventional procedure may reduce the risk of recurrence.
Tetravalent half-arc-transitive graphs of order <sup>p4</sup>
Feng, Yan-Quan,Kwak, Jin Ho,Xu, Ming-Yao,Zhou, Jin-Xin Elsevier 2008 European journal of combinatorics : Journal europ& Vol.29 No.3
<P><B>Abstract</B></P><P>A graph is half-arc-transitive if its automorphism group acts transitively on vertices and edges, but not on arcs. It is known that for a prime p there is no tetravalent half-arc-transitive graphs of order p or <SUP>p2</SUP>. Xu [M.Y. Xu, Half-transitive graphs of prime-cube order, J. Algebraic Combin. 1 (1992) 275–282] classified the tetravalent half-arc-transitive graphs of order <SUP>p3</SUP>. As a continuation, we classify in this paper the tetravalent half-arc-transitive graphs of order <SUP>p4</SUP>. It shows that there are exactly p−1 nonisomorphic connected tetravalent half-arc-transitive graphs of order <SUP>p4</SUP> for each odd prime p.</P>
Quan, Xianglan,Nguyen, Tuyet Thi,Choi, Seong-Kyung,Xu, Shanhua,Das, Ranjan,Cha, Seung-Kuy,Kim, Nari,Han, Jin,Wiederkehr, Andreas,Wollheim, Claes B.,Park, Kyu-Sang American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.7
<P>In pancreatic β-cells, ATP acts as a signaling molecule initiating plasma membrane electrical activity linked to Ca<SUP>2+</SUP> influx, which triggers insulin exocytosis. The mitochondrial Ca<SUP>2+</SUP> uniporter (MCU) mediates Ca<SUP>2+</SUP> uptake into the organelle, where energy metabolism is further stimulated for sustained second phase insulin secretion. Here, we have studied the contribution of the MCU to the regulation of oxidative phosphorylation and metabolism-secretion coupling in intact and permeabilized clonal β-cells as well as rat pancreatic islets. Knockdown of MCU with siRNA transfection blunted matrix Ca<SUP>2+</SUP> rises, decreased nutrient-stimulated ATP production as well as insulin secretion. Furthermore, MCU knockdown lowered the expression of respiratory chain complexes, mitochondrial metabolic activity, and oxygen consumption. The pH gradient formed across the inner mitochondrial membrane following nutrient stimulation was markedly lowered in MCU-silenced cells. In contrast, nutrient-induced hyperpolarization of the electrical gradient was not altered. In permeabilized cells, knockdown of MCU ablated matrix acidification in response to extramitochondrial Ca<SUP>2+</SUP>. Suppression of the putative Ca<SUP>2+</SUP>/H<SUP>+</SUP> antiporter leucine zipper-EF hand-containing transmembrane protein 1 (LETM1) also abolished Ca<SUP>2+</SUP>-induced matrix acidification. These results demonstrate that MCU-mediated Ca<SUP>2+</SUP> uptake is essential to establish a nutrient-induced mitochondrial pH gradient which is critical for sustained ATP synthesis and metabolism-secretion coupling in insulin-releasing cells.</P>
Aeromonas hydrophila cytosolic 5’-methylthioadenosine/S-adenosylhomocysteine nucleosidase MtaN-2
Jinli Chen,Fei Shang,Lulu Wang,Wei Liu,Yuanyuan Chen,Jing Lan,Liming Jin,Nam-Chul Ha,Chunshan Quan,Yongbin Xu 한국구조생물학회 2018 Biodesign Vol.6 No.3
5’-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) plays a critical role in diverse pathways in bacterial cells such as biological methylation, polyamine biosynthesis, methionine recycling, and bacterial quorum sensing. It has been known that MtaN catalyzes the hydrolysis of N-ribosidic bond of adenosine-based substrates such as S-adenosyl-L-homocysteine (SAH), S-methyl-5’-thioadenosine (MTA) and 5’-deoxyadenosine (5’-DOA). In Aeromonas hydrophila, there are two MtnN subfamily proteins: MtaN-1, a periplasmic protein with an N-terminal signal peptide; and MtaN-2, a cytosolic protein. In this study, MtaN-2 from A. hydrophila was successfully expressed and purified using Ni-NTA affinity, Q anion-exchange, and gel-filtration chromatography. We first crystallized apo MtaN-2 but it diffracted to a low resolution of 5.1 Å. New crystals suitable for diffraction were obtained by adding 2 mM adenosine, a substrate analog of MtaN-2 during purification process and the crystals diffracted to the resolution of 2.0 Å. The crystals belong to the trigonal space group P31 or P32, with unit-cell parameters of a = b = 74.94 Å and c = 185.21 Å. The asymmetric unit contains four complexes of MtaN-2 with hydrolysis products of adenosine.
Xu, Yongbin,Wang, Lulu,Chen, Jinli,Zhao, Jing,Fan, Shengdi,Dong, Yuesheng,Ha, Nam-Chul,Quan, Chunshan American Chemical Society 2017 Biochemistry Vol.56 No.40
<P>The Gram-negative, rod-shaped bacterium Aeromonas hydrophila has two multifunctional 5/-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) enzymes, MtaN-1 and MtaN-2, that differ from those in other bacteria. These proteins are essential for several metabolic pathways, including biological methylation, polyamine biosynthesis, methionine recycling, and bacterial quorum sensing. To gain insight into how these two proteins function, we determined four high-resolution crystal structures of MtaN-1 in its apo form and in complex with the substrates S-adenosyl-L-homocysteine, S'-methylthioadenosine, and 5'-deoxyadenosine. We found that the domain structures were generally similar, although slight differences were evident. The crystal structure demonstrates that AhMtaN-1 has an extension of the binding pocket and revealed that a tryptophan in the active site (Trp199) may playa major role in substrate binding, unlike in other MTAN proteins. Mutation of the Trp199 residue completely abolished the enzyme activity. Trp199 was identified as an active site residue that is essential for catalysis. Furthermore, biochemical characterization of AhMtaN-1 and AhMtaN-2 demonstrated that AhMtaN-1 exhibits inherent trypsin resistance that is higher than that of AhMtaN-2. Additionally, the thermally unfolded AhMtaN-2 protein is capable of refolding into active forms, whereas the thermally unfolded AhMtaN-1 protein does not have this ability. Examining the different biochemical characteristics related to the functional roles of AhMtaN-1 and AhMtaN-2 would be interesting. Indeed, the biochemical characterization of these structural features would provide a structural basis for the design of new antibiotics against A. hydrophila.</P>
Xu, Yongbin,Jo, Inseong,Wang, Lulu,Chen, Jinli,Fan, Shengdi,Dong, Yuesheng,Quan, Chunshan,Ha, Nam-Chul Elsevier 2017 Biochemical and biophysical research communication Vol.493 No.1
<P><B>Abstract</B></P> <P>Membrane fusion proteins (MFPs) play an essential role in the action of the drug efflux pumps and protein secretion systems in bacteria. The sporulation delaying protein (SDP) efflux pump YknWXYZ has been identified in diverse <I>Bacillus</I> species. The MFP YknX requires the ATP-binding cassette (ABC) transporter YknYZ and the Yip1 family protein YknW to form a functional complex. To date, the crystal structure, molecular function and mechanism of action of YknX remain unknown. In this study, to characterize the structural and biochemical roles of YknX in the functional assembly of YknWXYZ from <I>B. amyloliquefaciens</I>, we successfully obtained crystals of the YknX protein that diffracted X-rays to a resolution of 4.4 Å. We calculated an experimentally phased map using single-wavelength anomalous diffraction (SAD), revealing that YknX forms a hexameric assembly similar to that of MacA from Gram-negative bacteria. The hexameric assembly of YknX exhibited a funnel-like structure with a central channel and a conical mouth. Functional studies <I>in vitro</I> suggest that YknX can bind directly to peptidoglycan. Our study provides an improved understanding of the assembly of the YknWXYZ efflux pump and the role of YknX in the complex.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The functional and structural properties of the YknX from <I>B. amyloliquefaciens.</I> </LI> <LI> The three-dimensional structure of MFP YknX and it has a strong affinity toward peptidoglycan. </LI> <LI> The YknX may forms a hexameric assembly in the crystal packing. </LI> <LI> The YknX displayed a similar upside-down, funnel-shaped orientation as <I>Aa</I> MacA. </LI> </UL> </P>
( Hong-xu Yang ),( Yue Shang ),( Quan Jin ),( Yan-ling Wu ),( Jian Liu ),( Chun-ying Qiao ),( Zi-ying Zhan ),( Huan Ye ),( Ji-xing Nan ),( Li-hua Lian ) 한국응용약물학회 2020 Biomolecules & Therapeutics(구 응용약물학회지) Vol.28 No.4
In current study, we aimed to investigate whether the gentiopicroside (GPS) derived from Gentiana manshurica Kitagawa could block the progression of alcoholic hepatic steatosis to fibrosis induced by chronic ethanol intake. C57BL/6 mice were fed an ethanol- containing Lieber-DeCarli diet for 4 weeks. LX-2 human hepatic stellate cells were treated with GPS 1 h prior to transforming growth factor-β (TGF-β) stimulation, and murine hepatocyte AML12 cells were pretreated by GPS 1 h prior to ethanol treatment. GPS inhibited the expression of type I collagen (collagen I), α-smooth muscle actin (α-SMA) and tissue inhibitor of metal protease 1 in ethanol-fed mouse livers with mild fibrosis. In addition, the imbalanced lipid metabolism induced by chronic ethanol-feeding was ameliorated by GPS pretreatment, characterized by the modulation of lipid accumulation. Consistently, GPS inhibited the expression of collagen I and α-SMA in LX-2 cells stimulated by TGF-β. Inhibition of lipid synthesis and promotion of oxidation by GPS were also confirmed in ethanol-treated AML12 cells. GPS could prevent hepatic steatosis advancing to the inception of a mild fibrosis caused by chronic alcohol exposure, suggesting GPS might be a promising therapy for targeting the early stage of alcoholic liver disease.