51
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Deng YP, Zhu JB, Ji ZG, Liu JS, Shuai B, Li RX, Xu ZZ, Théberge F, Chin SL. Transverse evolution of a plasma channel in air induced by a femtosecond laser. OPTICS LETTERS 2006; 31:546-8. [PMID: 16496915 DOI: 10.1364/ol.31.000546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We investigate the evolution of filamentation in air by using a longitudinal diffraction method and a plasma fluorescence imaging technique. The diameter of a single filament in which the intensity is clamped increases as the energy of the pump light pulse increases, until multiple filaments appear.
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52
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Feng DH, Xu ZZ, Feng XL, Jia TQ, Li XX, Liu JS. Incoherent subharmonic light scattering in isotropic media. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:575-578. [PMID: 15649786 DOI: 10.1016/j.saa.2004.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Accepted: 05/07/2004] [Indexed: 05/24/2023]
Abstract
Incoherent subharmonic light scattering in isotropic media is a new kind of nonlinear light scattering, which involves single input photon and multiple output photons of equal frequency. We investigate theoretically the dependence of the subharmonic scattering intensity on the hyperpolarizability of molecules and the incident intensity using nonlinear optics theory similar to that used for Hyper-Rayleigh scattering and degenerate optical parametric oscillators. It is derived that the subharmonic scattering intensities grow exponentially or superexponentially with the hyperpolarizability of molecules and the incident intensity.
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Chen WH, Chiang TJ, Hsu MC, Liu JS. The validity of eye blink rate in Chinese adults for the diagnosis of Parkinson's disease. Clin Neurol Neurosurg 2003; 105:90-2. [PMID: 12691797 DOI: 10.1016/s0303-8467(02)00107-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We evaluated the eye blink rate (EBR) in healthy Chinese adults and Parkinson's disease (PD) patients. In healthy subjects, the EBR declined with age, was lower in women than men younger than 50 years of age, and did not differ from male PD patients older than 60 years or female PD patients older than 50 years. Accordingly, EBR is not a good indicator for bradykinesia in Chinese individual older than 50 years that is prevalent for PD onset also.
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Chen WH, Kao YF, Lan MY, Chang YY, Liu JS. A perturbation of antithrombin-III and protein C coupling associates with an increase of anti-beta2-glycoprotein I antibody in non-antiphospholipid antibody syndrome cerebral ischemia. Blood Coagul Fibrinolysis 2002; 13:703-9. [PMID: 12441909 DOI: 10.1097/00001721-200212000-00006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Anti-beta -glycoprotein I antibody (abetaGPI) has been recognized in raising the risk of cerebral ischemia in patients with antiphospholipid antibody syndrome (APS), especially by protein C (PC) axis perturbation. Although a high potential is also seen in non-APS patients, the mechanism is substantially unknown. In the present study, we examined the effect of abetaGPI on PC and antithrombin-III (AT-III) activity in non-APS patients with non-cardiac cerebral ischemia (NCCI). A total of 111 NCCI patients and 30 healthy controls were enrolled. They were free of APS manifestation, and their anticardiolipin antibody and lupus anticoagulant tests were within normal range. There were 14.4% patients found to have an abnormal increase of blood abetaGPI. The PC, AT-III, albumin, aminotransferases, creatinine, prothrombin time and activated partial thromboplastin time did not differ between our patients and controls, or patients with or without increased abetaGPI. However, a marked decrease of the PC/AT-III ratio was found in patients with increased abetaGPI. The correlation between PC and AT-III activity was highly significant in patients with an increase of abetaGPI (P = 0.001), only marginal in controls (P = 0.042), and was insignificant in patients with a normal abetaGPI (P = 0.277). The abetaGPI did not correlate to PC or AT-III activity in either patients or controls. These findings suggest that high PC/AT-III coupling may relate to NCCI in non-APS patients associated with an increase of abetaGPI. This coupling effect seems not to be caused by abetaGPI directly.
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Liu JS, Taghizadeh MR. Iterative algorithm for the design of diffractive phase elements for laser beam shaping. OPTICS LETTERS 2002; 27:1463-1465. [PMID: 18026480 DOI: 10.1364/ol.27.001463] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
An improved iterative algorithm for designing diffractive phase elements for laser beam shaping in free space is presented. The algorithm begins with the Gerchberg-Saxton approach to obtain a stable solution. This is followed by several new iterations, in which modified constraining functions are imposed in the Fourier domain while the phase distribution of each iteration remains unchanged. For super-Gaussian beam shaping suitable for inertial confinement fusion applications the mean-square errors of the amplitude and the intensity profile of the entire beam fitted to the corresponding parameters of the 12th-power super-Gaussian beam are approximately 0.035 and 9.75x10(-3), respectively. Approximately 97.4% of the incident energy is converged into the desired region.
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Liu JS, Kuo SR, Yin X, Beerman TA, Melendy T. DNA damage by the enediyne C-1027 results in the inhibition of DNA replication by loss of replication protein A function and activation of DNA-dependent protein kinase. Biochemistry 2001; 40:14661-8. [PMID: 11724580 DOI: 10.1021/bi015680c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Treatment of cells with the enediyne C-1027 is highly efficient at inducing single- and double-strand DNA breaks. This agent is highly cytotoxic when used at picomolar levels over a period of days. For this study, C-1027 has been used at higher levels for a much shorter time period to look at early cellular responses to DNA strand breaks. Extracts from cells treated with C-1027 for as little as 2 h are deficient in SV40 DNA replication activity. Treatment with low levels of C-1027 (1-3 nM) does not result in the presence of a replication inhibitor in cell extracts, but they are deficient in replication protein A (RPA) function. Extracts from cells treated with high levels of C-1027 (10 nM) do show the presence of a trans-acting inhibitor of DNA replication. The deficiency in RPA in extracts from cells treated with low levels of C-1027 can be fully complemented by the addition of exogenous RPA, and may be due to a C-1027-induced decrease in the extractability of RPA. This decrease in the extractability of RPA correlates with the appearance of many extraction-resistant intranuclear RPA foci. The trans-acting inhibitor of DNA replication induced by treatment of cells with high levels of C-1027 (10 nM) is DNA-dependent protein kinase (DNA-PK). DNA-PK is activated by the presence of DNA fragments induced by C-1027 treatment, and can be abrogated by removal of the DNA fragments. Although it is activated by DNA damage and phosphorylates RPA, DNA-PK is not required for either RPA focalization or loss of RPA replication activity.
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Liu JS, Marison IW, von Stockar U. Microbial growth by a net heat up-take: a calorimetric and thermodynamic study on acetotrophic methanogenesis by Methanosarcina barkeri. Biotechnol Bioeng 2001; 75:170-80. [PMID: 11536139 DOI: 10.1002/bit.1176] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To answer the intriguing question whether or not endothermic microbial growth exists, and in particular, to verify Heijnen and van Dijken's prediction (1992), acetotrophic methanogen, Methanosarcina barkeri, has been cultivated in a highly sensitive bench-scale calorimeter (an improved Bio-RC1 reaction calorimeter) in a pH auxostat fashion. A growth yield of 0.043 C-mol C-mol(-1) has been obtained and a cell density as high as 3 g L(-1) was attained. Heat uptake during growth has indeed been quantitatively measured with calorimetry, resulting in a heat yield of +145 kJ C-mol(-1). Thermodynamics of the growth of acetotrophic methanogens was analyzed in detail. The changes in Gibbs energy, enthalpy, and entropy during growth of M. barkeri were compared with some typical aerobic and anaerobic growth processes of different microorganisms on various substrates. In the growth of M. barkeri on acetate, the retarding effect of the positive enthalpy change on the driving force of growth is overcompensated by the large positive entropy change, resulting from converting one organic molecule (acetic acid) to two gaseous products, CH(4) and CO(2). Both the enthalpy and the entropy increases are due partially to the transition of these two products into the gaseous phase. The thermodynamic role of this phase transition for the growth process is analyzed. Microbial growth characterized by enthalpy increase and correspondingly by a large increase in entropy may be called enthalpy-retarded growth.
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Lu PC, Lai HC, Liu JS. A reevaluation and discussion on the threshold limit for hemolysis in a turbulent shear flow. J Biomech 2001; 34:1361-4. [PMID: 11522317 DOI: 10.1016/s0021-9290(01)00084-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
One major factor of red blood cell damage induced by artificial heart valves is the magnitude of turbulent shear stresses in the flow field. An often-cited threshold for hemolysis is 400 N/m(2) (Sallam and Hwang, Biorheology 21 (1984) 783). This value, however, was measured with a one-component laser Doppler anemometer and was not calculated from the major principal Reynolds shear stress, therefore underestimating the threshold. This study performed flow field measurements under similar conditions, using a two-component laser Doppler anemometer and determining major principal Reynolds shear stress, to reevaluate the hemolytic threshold as 800 N/m(2) with an exposure time of 1 ms. The Kolmogorov length scales, approximately 9 microm, are capable of inflicting direct damage to the red blood cells. These results will serve as a more accurate reference in future heart valve design and testing.
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Liu JS, Sabatti C, Teng J, Keats BJ, Risch N. Bayesian analysis of haplotypes for linkage disequilibrium mapping. Genome Res 2001; 11:1716-24. [PMID: 11591648 PMCID: PMC311130 DOI: 10.1101/gr.194801] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Haplotype analysis of disease chromosomes can help identify probable historical recombination events and localize disease mutations. Most available analyses use only marginal and pairwise allele frequency information. We have developed a Bayesian framework that utilizes full haplotype information to overcome various complications such as multiple founders, unphased chromosomes, data contamination, and incomplete marker data. A stochastic model is used to describe the dependence structure among several variables characterizing the observed haplotypes, for example, the ancestral haplotypes and their ages, mutation rate, recombination events, and the location of the disease mutation. An efficient Markov chain Monte Carlo algorithm was developed for computing the estimates of the quantities of interest. The method is shown to perform well in both real data sets (cystic fibrosis data and Friedreich ataxia data) and simulated data sets. The program that implements the proposed method, BLADE, as well as the two real datasets, can be obtained from http://www.fas.harvard.edu/~junliu/TechRept/01folder/diseq_prog.tar.gz.
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Guo QM, Liu JS. [Effects of opioids on Ca2+/calmodulin dependent protein kinase signal pathway in NG108-15 cells]. YAO XUE XUE BAO = ACTA PHARMACEUTICA SINICA 2001; 36:652-6. [PMID: 12580100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
AIM To observe the change of Ca2+/calmodulin dependent protein kinase II (CaMK II) signal pathway in opioid dependent NG108-15 cells. METHODS NG108-15 cells were used as an in vitro model system. Competitive protein binding assay and radioimmunoassay were used to examine the intracellular cAMP accumulation. Calmodulin activity was assayed by PDE method. CaMK II activity was assayed by gamma-32 P incorporation of syntide-2. RESULTS DPDPE long-term treatment increased calmodulin activity and CaMK II activity in both cytoplasm and nucleus of NG108-15 cells. Specific calmodulin antagonist W-7 was found to significantly inhibit the elevation of calmodulin and CaMK II activity which resulted from DPDPE long-term treatment, and CaMK II inhibitor KN-62 also inhibited elevation of CaMK II activity by DPDPE long-term treatment. When naloxone was added to NG108-15 cells which were long-term treated by DPDPE, calmodulin and CaMK II activity increased, indicating that naloxone withdrawal can increase Ca2+/CaMK II pathway activity. CONCLUSION The results indicate that Ca2+/CaMK II pathway was involved in the mechanisms of opioids dependence when DPDPE was long-term administered to NG108-15 cells.
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Liu JQ, Shen QQ, Liu JS, Wu DL, Wang JT. [Studies on the chemical constituents from Chrysanthemum morifolium Ramat]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 2001; 26:547-8. [PMID: 12776368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
OBJECTIVE To study the chemical constituents of Chrysanthemum morifolium. METHOD Separated the constituents by means of chromatography and identified their structures by chemical and spectroscopic analysis. RESULT Three compounds of flavonoid were identified as acacetin-7-O-beta-D-glucoside, apigenin-7-O-beta-D-glucoside and luteolin-7-O-beta-D-glucoside. CONCLUSION These compounds were obtained from C. morifolium for the first time.
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Liu X, Brutlag DL, Liu JS. BioProspector: discovering conserved DNA motifs in upstream regulatory regions of co-expressed genes. PACIFIC SYMPOSIUM ON BIOCOMPUTING. PACIFIC SYMPOSIUM ON BIOCOMPUTING 2001:127-38. [PMID: 11262934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The development of genome sequencing and DNA microarray analysis of gene expression gives rise to the demand for data-mining tools. BioProspector, a C program using a Gibbs sampling strategy, examines the upstream region of genes in the same gene expression pattern group and looks for regulatory sequence motifs. BioProspector uses zero to third-order Markov background models whose parameters are either given by the user or estimated from a specified sequence file. The significance of each motif found is judged based on a motif score distribution estimated by a Monte Carlo method. In addition, BioProspector modifies the motif model used in the earlier Gibbs samplers to allow for the modeling of gapped motifs and motifs with palindromic patterns. All these modifications greatly improve the performance of the program. Although testing and development are still in progress, the program has shown preliminary success in finding the binding motifs for Saccharomyces cerevisiae RAP1, Bacillus subtilis RNA polymerase, and Escherichia coli CRP. We are currently working on combining BioProspector with a clustering program to explore gene expression networks and regulatory mechanisms.
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Liu JS, Zhao ML, Brosnan CF, Lee SC. Expression of inducible nitric oxide synthase and nitrotyrosine in multiple sclerosis lesions. THE AMERICAN JOURNAL OF PATHOLOGY 2001; 158:2057-66. [PMID: 11395383 PMCID: PMC1891989 DOI: 10.1016/s0002-9440(10)64677-9] [Citation(s) in RCA: 243] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitric oxide generated by the inducible form of nitric oxide synthase (iNOS) may contribute to the pathogenesis of multiple sclerosis (MS). In this report, we studied postmortem tissues of MS patients for the expression of iNOS by in situ hybridization and immunocytochemistry. Immunocytochemistry for nitrotyrosine, a putative footprint for peroxynitrite formation was also performed. In acute MS lesions, intense reactivity for iNOS mRNA and protein was detected in reactive astrocytes throughout the lesion and in adjacent normal appearing white matter. Staining of macrophages, inflammatory cell infiltrates, and endothelial cells was variable from case to case, but generally detected only in acute lesions. In chronic MS lesions reactive astrocytes at the lesion edge were positive for iNOS whereas the lesion center was nonreactive. Normal appearing white matter demonstrated little reactivity, as did tissues from noninflamed control brains. Staining for nitrotyrosine was also detected in acute but not chronic MS lesions, and displayed a diffuse parenchymal, membranous, and perivascular pattern of immunoreactivity. These results support the conclusion that iNOS is induced in multiple cell types in MS lesions and that astrocyte-derived nitric oxide could be important in orchestrating inflammatory responses in MS, particularly at the blood-brain barrier.
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McHugh MM, Yin X, Kuo SR, Liu JS, Melendy T, Beerman TA. The cellular response to DNA damage induced by the enediynes C-1027 and neocarzinostatin includes hyperphosphorylation and increased nuclear retention of replication protein a (RPA) and trans inhibition of DNA replication. Biochemistry 2001; 40:4792-9. [PMID: 11294647 DOI: 10.1021/bi001668t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study examined the cellular response to DNA damage induced by antitumor enediynes C-1027 and neocarzinostatin. Treatment of cells with either agent induced hyperphosphorylation of RPA32, the middle subunit of replication protein A, and increased nuclear retention of RPA. Nearly all of the RPA32 that was not readily extractable from the nucleus was hyperphosphorylated, compared to < or =50% of the soluble RPA. Enediyne concentrations that induced RPA32 hyperphosphorylation also decreased cell-free SV40 DNA replication competence in extracts of treated cells. This decrease did not result from damage to the DNA template, indicating trans-acting inhibition of DNA replication. Enediyne-induced RPA hyperphosphorylation was unaffected by the replication elongation inhibitor aphidicolin, suggesting that the cellular response to enediyne DNA damage was not dependent on elongation of replicating DNA. Neither recovery of replication competence nor reversal of RPA effects occurred when treated cells were further incubated in the absence of drug. C-1027 and neocarzinostatin doses that caused similar levels of DNA damage resulted in equivalent increases in RPA32 hyperphosphorylation and RPA nuclear retention and decreases in replication activity, suggesting a common response to enediyne-induced DNA damage. By contrast, DNA damage induced by C-1027 was at least 5-fold more cytotoxic than that induced by neocarzinostatin.
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Chen WH, Liu JS. An unusual increase of blood anti-beta 2-glycoprotein-I antibody but not antiphospholipid antibody in cerebral ischemia--a case report. Angiology 2001; 52:149-54. [PMID: 11228090 DOI: 10.1177/000331970105200211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
An abnormal increase in anti-beta2-glycoprotein I antibodies (abeta2GPI) is capable of producing thrombosis and the vasculopathy-simulating antiphospholipid antibody (aPL). However, it is rarely described in cerebral ischemia without an association with aPL. The authors report a middle-aged man who experienced recurrent cerebral ischemia and diffuse cerebral stenosis without the apparent traditional cardiovascular risk factor. He was free of antiphospholipid/cofactor syndrome (APCS) and systemic lupus erythematosus (SLE). An increase of blood abeta2GPI was detected in serial measurements. The aPL, Venereal Disease Research Laboratory (VDRL) test, Coombs' test, and antinuclear factor were negative. Activated partial thromboplastin time was normal. This patient is a reminder to consider abeta2GPI in an unexplained recurrent cerebral thrombosis and cerebral artery stenosis even when the typical clinical manifestation or laboratory data of APCS is absent.
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McCue L, Thompson W, Carmack C, Ryan MP, Liu JS, Derbyshire V, Lawrence CE. Phylogenetic footprinting of transcription factor binding sites in proteobacterial genomes. Nucleic Acids Res 2001; 29:774-82. [PMID: 11160901 PMCID: PMC30389 DOI: 10.1093/nar/29.3.774] [Citation(s) in RCA: 198] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Toward the goal of identifying complete sets of transcription factor (TF)-binding sites in the genomes of several gamma proteobacteria, and hence describing their transcription regulatory networks, we present a phylogenetic footprinting method for identifying these sites. Probable transcription regulatory sites upstream of Escherichia coli genes were identified by cross-species comparison using an extended Gibbs sampling algorithm. Close examination of a study set of 184 genes with documented transcription regulatory sites revealed that when orthologous data were available from at least two other gamma proteobacterial species, 81% of our predictions corresponded with the documented sites, and 67% corresponded when data from only one other species were available. That the remaining predictions included bona fide TF-binding sites was proven by affinity purification of a putative transcription factor (YijC) bound to such a site upstream of the fabA gene. Predicted regulatory sites for 2097 E.coli genes are available at http://www.wadsworth.org/resnres/bioinfo/.
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Su YF, Guo DA, Cui YJ, Liu JS, Zheng JH. A new phenolic glycoside and a new trans-clerodane diterpene from Conyza blinii. JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH 2001; 3:229-233. [PMID: 11491399 DOI: 10.1080/10286020108041395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A new phenolic glycoside, 4-propionyl-2,6-dimethoxyphenyl beta-D-glucopyranoside (1) and a new trans-clerodane diterpene named 19-deacetylconyzalactone (2), were isolated from the aerial parts of Conyza blinii.
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Liu JS, Ishikawa I. Communication between acquired renal cysts and renal tubules. Nephron Clin Pract 2000; 86:243-4. [PMID: 11015022 DOI: 10.1159/000045771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Liu JS, John GR, Sikora A, Lee SC, Brosnan CF. Modulation of interleukin-1beta and tumor necrosis factor alpha signaling by P2 purinergic receptors in human fetal astrocytes. J Neurosci 2000; 20:5292-9. [PMID: 10884313 PMCID: PMC6772323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
In human astrocytes, interleukin-1beta (IL-1beta) is a potent inducer of genes associated with inflammation. In this study, we tested the hypothesis that in primary cultures of human fetal astrocytes signaling by the P2 purinergic nucleotide receptor pathway contributes to, or modulates, cytokine-mediated signal transduction. Calcium imaging studies indicated that most cells in culture responded to ATP, whereas only a subpopulation responded to UTP. Pretreatment of astrocytes with P2 receptor antagonists, including suramin and periodate oxidized ATP (oATP), resulted in a significant downregulation of IL-1beta-stimulated expression of nitric oxide, tumor necrosis factor (TNFalpha), and IL-6 at both the protein and mRNA levels, without affecting cell viability. In cells transiently transfected with reporter constructs, IL-1beta demonstrated more potent activation of the transcription factors nuclear factor -kappaB (NF-kappaB) and activator protein-1 (AP-1) than TNFalpha. However, pretreatment with oATP downregulated activation of NF-kappaB and AP-1 by IL-1beta or TNFalpha. Electromobility shift assays using oligonucleotides containing specific NF-kappaB binding sequences confirmed that pretreatment with oATP or apyrase attenuated cytokine-mediated induction of this transcription factor. From these data, we conclude that P2 receptor-mediated signaling intersects with that of IL-1beta and TNFalpha to regulate responses to cytokines in the CNS. Because inflammation, trauma, and stress all lead to the release of high levels of extracellular nucleotides, such as ATP and UTP, signaling via P2 receptors may provide a mechanism whereby cells can sense and respond to events occurring in the extracellular environment and can fine tune the transcription of genes involved in the inflammatory response.
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Morgan AC, Chang HY, Liu JS, Hua LL, Lee SC. High extracellular potassium modulates nitric oxide synthase expression in human astrocytes. J Neurochem 2000; 74:1903-12. [PMID: 10800933 DOI: 10.1046/j.1471-4159.2000.0741903.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Inducible nitric oxide synthase (iNOS) is a molecule of great interest, given the numerous biological activities of nitric oxide and the documented expression of iNOS in several CNS pathologies. There also appears to be species-dependent regulation of iNOS expression as well as CNS-specific regulation. In this study, we have examined cultures of cytokine-activated primary human astrocytes as a model system with which to study the mechanisms of iNOS regulation in human CNS. As one of the major functions of astrocytes is spatial buffering of K+ ion, we examined the effect of high extracellular KCI on astrocyte iNOS expression. The results demonstrate that KCI at 25-75 mM potently inhibits astrocyte nitrite production stimulated by interleukin-1 (IL-1)/interferon-gamma (IFNgamma). In addition, several potassium channel inhibitors such as CsCl, tetraethylammonium, and 4-aminopyridine as well as nigericin inhibited astrocyte iNOS expression induced by IL-1/IFNgamma. These results demonstrate a novel role for astrocyte potassium channel activity in modulation of astrocyte function. They further suggest neural-specific mechanisms for glial iNOS regulation.
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Liu JS, Lu PC, Chu SH. Turbulence characteristics downstream of bileaflet aortic valve prostheses. J Biomech Eng 2000; 122:118-24. [PMID: 10834151 DOI: 10.1115/1.429643] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study was focused on a series of in vitro tests on the turbulent flow characteristics of three bileaflet aortic valves: St. Jude Medical (SJM), CarboMedics (CM), and Edwards Tekna (modified Duromedics, DM). The flow fields of the valves were measured in a pulsatile flow model with a laser-Doppler anemometer (LDA) at the aortic sinus area downstream of the valves. The heart rate was set at 70 beats per minute, the cardiac output was maintained at 5 liters per minute, and the aortic pressure wave forms were kept within the physiological range. Cycle-resolved analysis was applied to obtain turbulence data, including mean velocity, Reynolds stresses, autocorrelation coefficients, energy spectral density functions, and turbulence scales. The Reynolds shear stresses of all three valves induced only minor damage to red blood cells, but directly damaged the platelets, increasing the possibility of thrombosis. The smallest turbulence length scale, which offers a more reliable estimate of the effects of turbulence on blood cell damage, was three times the size of red blood cells and five times the size of platelets. This suggests that there is more direct interaction with the blood cells, thus causing more damage.
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Liu JS, Chang YY, Wu HS, Huang CY, Chen WH, Lan MY, Kao YF, Chen SS. Transtentorial cerebellar c-jun expression after focal cerebral cortical injury in mice. Neurosci Lett 2000; 282:85-8. [PMID: 10713402 DOI: 10.1016/s0304-3940(00)00865-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Delayed and remote effect of focal cerebral cortical lesion on cerebellum remains unclear. The c-Jun, an inducible transcription factor of cellular immediate early gene, is the predominant transcription factor and consistent marker for neurons that respond to stress or injury. We use a mouse cryogenic injury model to study the spatial and temporal changes of c-jun in the cerebellum after focal neocortical lesion. A transient and moderate expression of c-jun mRNA was found in the cerebellum with central dominance since 3 day postinjury and gradually subsided within 2 weeks. A distinct increment of c-Jun protein expression in Purkinje cells of the bilateral cerebellar hemispheres with focal connotation in the vermis was detected since 1 week postinjury. These findings suggest that the delayed and remote c-jun expression of the cerebellum, functionally connected with the cerebral cortex, indicate transneuronal gene activation.
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Lin BY, Ma T, Liu JS, Kuo SR, Jin G, Broker TR, Harper JW, Chow LT. HeLa cells are phenotypically limiting in cyclin E/CDK2 for efficient human papillomavirus DNA replication. J Biol Chem 2000; 275:6167-74. [PMID: 10692408 DOI: 10.1074/jbc.275.9.6167] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human papillomaviral (HPV) origin-containing plasmids replicate efficiently in human 293 cells or cell extracts in the presence of HPV origin-recognition protein E2 and replication initiation protein E1, whereas cervical carcinoma-derived, HPV-18-positive HeLa cells or cell extracts support HPV DNA replication poorly. We recently showed that HPV-11 E1 interacts with cyclin/cyclin-dependent kinase (cdk) complexes through an RXL motif and is a substrate for these kinases. E1 mutations in this motif or in candidate cdk phosphorylation sites are impaired in replication, suggesting a role for cdks in HPV replication. We now demonstrate that one limiting activity in HeLa cells is cyclin E/CDK2. Purified cyclin E/CDK2 or cyclin E/CDK3 complex, but not other cdks, partially complemented HeLa cell extracts. Cyclin E/CDK2 expression vectors also enhanced transient HPV replication in HeLa cells. HeLa cell-derived HPV-18 E1 protein is truncated at the carboxyl terminus but can associate with cyclin E/CDK2. This truncated E1 was replication-incompetent and inhibited cell-free HPV replication. These results indicate that HeLa cells are phenotypically limiting in cyclin E/CDK2 for efficient HPV replication, most likely due to sequestration by the endogenous, defective HPV-18 E1 protein. Further analyses of the regulation of HPV E1 and HPV replication by cyclin E may shed light on the roles of cyclin E/CDK2 in cellular DNA replication.
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Sun L, Weng LL, Zheng H, Liu JS. Effects of XW630 on cell proliferation, iNOS activity, and cGMP content in human osteoblast-like cell line TE85. Acta Pharmacol Sin 2000; 21:261-4. [PMID: 11324428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
AIM To study the effects of 2-[3-estrone-N-ethyl-piperazine-methyl] tetracycline (XW630) in human osteoblast-like cell line TE85. METHODS [3H]Thymidine incorporation and cell count for cell proliferation, radioimmunoassay for cyclic GMP (cGMP) content, and monitoring the conversion of [3H]arginine for inducible nitric-oxide synthase (iNOS) activity assay. RESULTS After treatment with XW630 for 48 h, [3H]thymidine incorporation and cell numbers increased by 62.7% and 96.9%, respectively. NG-monomethyl-L-arginine (L-NMMA, an NOS inhibitor) induced a concentration-dependent inhibitory effect on the proliferation after treatment for 48 h. The inhibitory effect was prevented partially by XW630 (1.0 nmol.L-1). After treatment with XW630 for 12-48 h, iNOS activity and cGMP concentration increased in time-dependent manners. CONCLUSION XW630 stimulated cell proliferation, enhanced iNOS activity and cGMP content in human osteoblast-like cell line TE85.
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Sun L, Qiu MC, Weng LL, Zheng H, Liu JS. Effects of 2-[3-estrone-N-ethyl-piperazine-methyl]tetracycline (XW630) on osteoporosis in ovariectomized rats. Acta Pharmacol Sin 2000; 21:200-4. [PMID: 11324415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
AIM To study the effects of 2-[3-estrone-N-ethyl-piperazine-methyl]tetracycline (XW630) on experimental osteoporosis in ovariectomized (OVX) rats. METHODS Serum estradiol (E2) content and bone 1-carboxyglutamic acid-containing protein (BGP) content were measured by radioimmunoassay. With undecalcified bone section and tetracycline intraperitoneal labeling, the bone static and dynamic data were studied in right femur samples. RESULTS After treatment with XW630 2.5 mg.kg-1, serum BGP content increased by 75.7% but there was no change in serum E2 content and uterus weight compared with OVX rats. Compared with OVX rats, the static data of trabecular bone volume/total tissue volume, trabecular bone volume/sponge bone volume, and mean trabecular plate density were enhanced after treatment with XW630 for 13 wk. The dynamic data of single-labeled surface, double-labeled surface, trabecular osteoid surface, and bone formation rate in tissue level in XW630 group were increased and osteoid maturation period was shortened. CONCLUSION XW630 enhanced bone activation frequency and increased trabecular connectivity, stability, and strength. XW630 stimulated bone formation and inhibited bone resorption with no effect on reproductive system.
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