1701
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Chen Q, Bernstein IB. Numerical study of the one-dimensional hydrogen atom in an external time-dependent electric field. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1993; 47:4099-4113. [PMID: 9909416 DOI: 10.1103/physreva.47.4099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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1702
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Xie B, Shi H, Chen Q, Ho CT. Antioxidant properties of fractions and polyphenol constituents from green, oolong and black teas. PROCEEDINGS OF THE NATIONAL SCIENCE COUNCIL, REPUBLIC OF CHINA. PART B, LIFE SCIENCES 1993; 17:77-84. [PMID: 7809277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Green, oolong and black teas were extracted with water, and then the water extracts were extracted separately with three types of solvent, chloroform, ethyl acetate and butanol, to obtain eight fractions. Major flavanol was extracted by EtOAc, while most of the alkaloid was in the chloroform fraction. Thearubigin was greatest in the butanol fraction, and most of the amino acid remained in the water fraction. All fractions were systematically analyzed by UV spectrophotometer and reverse phase HPLC for those important components existing in green tea, oolong tea, and black tea. The pure compounds of (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG), free theaflavin, theaflavin monogallate-A, theaflavin monogallate-B, and theaflavin digallate were separated by LH-20 chromatography and reverse phase HPLC. All fractions and pure compounds were assayed for antioxidant activity and lipoxygenase inhibition activity. Flavanol showed very strong antioxidant activity and lipoxygenase inhibition.
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1703
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Seifert H, Kelly JJ, Feldman AE, Flanders BS, Khandaker MA, Chen Q, Bacher AD, Berg GP, Stephenson EJ, Karen P, Norum BE, Welch P, Scott A. Effective interaction for 16O(p,p') and 40Ca(p,p') at Ep=200 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1993; 47:1615-1635. [PMID: 9968609 DOI: 10.1103/physrevc.47.1615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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1704
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Abstract
Two forms of rat brain cytosolic diacylglycerol kinase (EC2.7.1.107) were separated by heparin-agarose column chromatography. These forms, designated DGK-I and DGK-II, were not interconvertible as determined by rechromatography. DGK-I and DGK-II had respective molecular masses of 88 and 180 kDa, as measured by Sepharose 6B chromatography. Both forms preferred diacylglycerol over monoacylglycerol and were insensitive to R59022. DGK-II, but not DGK-I, was activated by an activator substance prepared from chicken egg yolk. DGK-II was activated by a rat brain cytosolic activator and was exclusively sensitive to 5'-AMP-mediated inactivation. Further studies revealed that these two forms had the following distinct characteristics: (a) substrate specificity, (b) inhibition by heparin, (c) sensitivity to lysine-containing polyamino acids, and (d) responses to different phospholipids. In general, DGK-II was more responsive to various inhibitors and activators, making it a prime candidate for a regulatable enzyme.
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1705
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Soghomonian V, Chen Q, Haushalter RC, Zubieta J, O'connor CJ. An Inorganic Double Helix: Hydrothermal Synthesis, Structure, and Magnetism of Chiral [(CH3)2NH2]K4[V10O10(H2O)2(OH)4(PO4)7]{middle dot}4H2O. Science 1993; 259:1596-9. [PMID: 17733025 DOI: 10.1126/science.259.5101.1596] [Citation(s) in RCA: 319] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Very complicated inorganic solids can be self-assembled from structurally simple precursors as illustrated by the hydrothermal synthesis of the vanadium phosphate, [(CH(3))(2)NH(2)]K(4)[V(10)O(10)(H(2)O)(2)(OH)(4)(PO(4))(7)].4H(2)O, 1, which contains chiral double helices formed from interpenetrating spirals of vanadium oxo pentamers bonded together by P(5+). These double helices are in turn intertwined with each other in a manner that generates unusual tunnels and cavities that are filled with (CH(3))(2)NH(2)(+) and K(+) cations, respectively. The unit cell contents of dark blue phosphate 1, which crystallizes in the enantiomorphic space group P4(3) with lattice constants a = 12.130 and c = 30.555 angstroms, are chiral; only one enantiomorph is present in a given crystal. Magnetization measurements show that 1 is paramagnetic with ten unpaired electrons per formula unit at higher temperatures and that antiferromagnetic interactions develop at lower temperatures.
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1706
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Liu W, Su Z, Wang L, Xu S, Chen Q, Zhang Z. [The number, distribution and effects of interleukin-2 receptor and CD4 antigens in benign and malignant lymphoproliferative diseases]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1993; 24:13-17. [PMID: 8340084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
An analysis of immunophenotypes was made in benign and malignant lymphoproliferative diseases (35 cases) and short cultured lymphocytes of chronic tonsillitis (15 cases). The number, distribution and variation of interleukin-2 receptor (IL-2R, CD25) and CD4 positive cells in the above lesions were studied. The results showed that (1) there were more or less IL-2R+ and CD4+ cells presented in the tissues of benign lymphoproliferative lesions; (2) IL-2R antigen was also presented in some tumor and non-tumor cells with CD4+ reaction but it was not found in the cells with CD1+ or/and CD8+ reactions; (3) IL-2R and CD4 antigens were expressed in the proliferated lymphocytes stimulated by PHA. Although IL-2R antigen is not a specific marker to certain types of lymphocytes, it has some relations with immunophenotypes of lymphocytes. The functions and effects of IL-2, IL-2R and helper T lymphocytes were also discussed.
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1707
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Chen Q, Kong F, Cao L. Synthesis, conformational analysis, and the glycosidic coupling reaction of substituted 2,7-dioxabicyclo[4.1.0]heptanes: 1,2-anhydro-3,4-di-O-benzyl-beta-L- and beta-D-rhamnopyranoses. Carbohydr Res 1993; 240:107-17. [PMID: 8458005 DOI: 10.1016/0008-6215(93)84176-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
1,2-Anhydro-3,4-di-O-benzyl-alpha-L-rhamnopyranose was synthesized from L-rhamnose, while the D-enantiomer was synthesized from methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-mannopyranoside. For both of the syntheses, the key intermediates were 2-O-acetyl-3,4-di-O-benzyl-alpha-D- and -alpha-L-rhamnopyranosyl chlorides that were quantitatively prepared from the corresponding diacetates by chlorination. Ring closure of the chlorides was carried out readily with potassium tert-butoxide in oxolane, and crystalline 1,2-anhydro-3,4-di-O-benzyl-beta-D- and beta-L-rhamnopyranose were obtained in high yields. Conformational calculations, which were carried out using vicinal proton-proton coupling constants by the modified Karplus equation, suggested that the conformations of the pyranose rings of the title compounds were basically a half chair (4H5) with some flattening at C-4. Force-field calculations (MMP2) confirmed the experimental conformation with good agreement. The coupling reaction of the 1,2-anhydro-L-rhamnose ether with 1,2;3,4-di-O-isopropylidene-alpha-D-galactopyranose was effected in oxolane by catalysis by a Lewis acid, and only the alpha-linked disaccharide was obtained.
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1708
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Chen Q, Nilsson A. Desaturation and chain elongation of n - 3 and n - 6 polyunsaturated fatty acids in the human CaCo-2 cell line. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1166:193-201. [PMID: 8443237 DOI: 10.1016/0005-2760(93)90097-s] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Human CaCo-2 cells were incubated with [14C]linoleic (18:2(n - 6)), [14C]linolenic (18:3(n - 3)) and [3H]eicosapentaenoic acid (20:5(n - 3)), and the interconversion of the radioactive fatty acids to higher homologues and their acylation into triacylglycerols (TG) and phospholipids were examined. An active conversion of [14C]18:3 to [14C]20:5 and [14C]docosapentaenoic acid (22:5(n - 3)) and of [3H]20:5 to [3H]22:5, but not to [3H]docosahexaenoic acid (22:6(n - 3)) was observed. In relation to the amounts that had been incorporated into cellular phospholipids and TG, the interconversion of [14C]18:3 clearly exceeded that of [14C]18:2. Addition of 10-100 microM 18:2 or 10-50 microM arachidonic acid (20:4(n - 6)) increased the percent interconversion of [14C]18:2 to [14C]20:4. E.g., addition of 50 microM 20:4 increased the formation of [14C]20:4 from 4.4 +/- 0.1% to 5.9 +/- 0.8%, decreased the incorporation into phospholipids from 64.8 +/- 6.3% to 31.4 +/- 1.2% and increased the incorporation into TG from 8.8 +/- 0.4% to 28.8 +/- 1.1%. In contrast, addition of 10-100 microM 18:3 or 20:5 significantly decreased the interconversion of both [14C]18:2 and [14C]18:3. E.g., addition of 50 microM 20:5 decreased the formation of [14C]20:4 from [14C]18:2 from 4.4 +/- 0.1% to 0.9 +/- 0.1%, whereas the effects on the acylation reactions were very similar to those of 20:4. 20:5 also decreased the formation of interconversion products from [14C]18:3. 18:2 and 20:4 caused a smaller decrease in the formation of [14C]20:5 and actually increased percent conversion to [14C]22:5. The percent conversion of [3H]20:5 to [3H]22:5 was also increased by the addition of 50-100 microM unlabeled 20:5. [14C]18:2 and [14C]18:3 were predominantly incorporated into phosphatidylcholine (PC) whereas more of the radioactive 20:4, 20:5 and 22:5 was incorporated into phosphatidylethanolamine (PE). An active fatty acid interconversion catalyzed by delta 6 and delta 5 desaturases thus occurs in the human CaCo-2 cell line, whereas conversion of 20:5(n - 3) to 22:6(n - 3) could not be demonstrated. The desaturation-elongation pathway has a preference for 18:3(n - 3) and is subjected to an efficient feedback regulation by 20:5(n - 3). Formation of 22:5 increases with available 20:5 mass and by the presence of other polyunsaturated fatty acids competing with 20:5 for acylation into phospholipids.
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1709
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Chen Q, Wang ZH. Exact dispersion relations for TM waves guided by thin dielectric films bounded by nonlinear media. OPTICS LETTERS 1993; 18:260. [PMID: 19802103 DOI: 10.1364/ol.18.000260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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1710
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Chen Q, Fitch JM, Gibney E, Linsenmayer TF. Type II collagen during cartilage and corneal development: immunohistochemical analysis with an anti-telopeptide antibody. Dev Dyn 1993; 196:47-53. [PMID: 7687475 DOI: 10.1002/aja.1001960106] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have examined the pattern of immunoreactivity of a monoclonal antibody, II-5B2, with specificity for an epitope which resides within the NH2-terminal extension peptide (telopeptide) of the avian type II collagen molecule. This epitope is available in regions of matrix where de novo synthesis of the molecule is ongoing, but not where synthesis has ceased and maturation and crosslink formation have occurred. Within the cartilaginous growth plate, the epitope disappears from the matrix soon after the chondrocytes become hypertrophic; within the cornea, the epitope disappears subjacent to the epithelium. The II-5B2 epitope is not made available by a variety of procedures shown to remove potentially masking substances and to disrupt fibrillar organization. It is rendered available, however, when covalent crosslink formation between collagen molecules is blocked through administration of beta-aminopropionitrile or penicillamine. In contrast, the epitope of another monoclonal antibody against type II collagen, II-II6B3, which resides in the triple-helical domain of the molecule, in cartilage is present throughout the growth plate including the hypertrophic zone, and in cornea extends for a considerable distance into the stroma. Thus, it is available for antibody binding regardless of fibril maturation and crosslinking. These data suggest that the II-5B2 epitope becomes unavailable when the telopeptide becomes crosslinked. By using these two monoclonal antibodies in serial sections, one can establish the crosslinking pattern of type II collagen in the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
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1711
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Chen Q, Gibney EP, Leach RM, Linsenmayer TF. Chicken tibial dyschondroplasia: a limb mutant with two growth plates and possible defects of collagen crosslinking. Dev Dyn 1993; 196:54-61. [PMID: 7687476 DOI: 10.1002/aja.1001960107] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In the cartilaginous epiphyseal growth plate, extracellular matrix molecules such as collagens are believed to play important roles during both normal and abnormal development. One defect of the epiphyseal plate occurs in chickens with a condition termed tibial dyschondroplasia (TD). This abnormality occurs in certain strains of juvenile chickens and other rapidly developing animals. It is characterized by the presence of a mass of avascular, uncalcified cartilage which is retained in the proximal metaphysis of the tibiotarsus. To elucidate the developmental events which may be involved in this lesion, we have performed both immunohistochemistry and in situ hybridizations for collagen types II and X, known components of the extracellular matrix of the growth plate. By immunohistochemical analyses, the TD lesion contains both of these collagen types; therefore, the presence of these molecules per se is not sufficient for calcification of vascularization to occur. Since type X collagen is expressed exclusively in hypertrophic cartilage, the chondrocytes in the lesion must have undergone hypertrophy before their developmental arrest. The matrix of the lesion also reacted with a monoclonal antibody which is directed against an epitope in the NH2-terminal telopeptide of the alpha 1(II) chain. Our previous data suggest that this epitope is rendered unavailable in type II collagen which has undergone crosslink formation; its availability in the lesion suggests that crosslinking may be abnormal. Lastly, analyses by in situ hybridization failed to detect mRNA for either type II or type X collagen within the lesion, but chondrocytes distal to the lesion do contain mRNAs for these collagens in a spatial pattern suggesting the presence of a second growth plate.
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1712
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Chen Q, Yu K, Stevens JL. Regulation of the cellular stress response by reactive electrophiles. The role of covalent binding and cellular thiols in transcriptional activation of the 70-kilodalton heat shock protein gene by nephrotoxic cysteine conjugates. J Biol Chem 1992; 267:24322-7. [PMID: 1447182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The cytotoxicity of nephrotoxic cysteine conjugates (NCC) in the renal epithelial cell line, LLC-PK1, is due to the covalent binding of a reactive electrophilic metabolite produced from NCC metabolism by cysteine conjugate beta-lyase. Covalent binding of NCC-derived reactive metabolites leads to a cascade of events including depletion of cellular non-protein sulfhydryls, increased cytosolic free calcium, and lipid peroxidation, which is ultimately responsible for cell death. We have used this model to investigate the signalling mechanism(s) through which reactive electrophiles increase synthesis of the 70-kD heat shock protein (HSP70). NCC treatment resulted in increased HSP70 synthesis as well as time- and dose-dependent increases in hsp70 mRNA in LLC-PK1 cells. The induction of hsp70 mRNA was blocked by actinomycin D, and nuclear run-on experiments showed that the hsp70 gene was transcriptionally activated. Inhibition of protein synthesis did not block the increase in hsp70 mRNA or transcriptional activation of the hsp70 gene suggesting that induction occurs due to activation of existing transcription factors. Inhibiting the covalent binding with a beta-lyase inhibitor, aminooxyacetic acid, blocked the increase in hsp70 mRNA. Agents which do not alter binding but do prevent toxicity by blocking the rise in cytosolic free calcium and lipid peroxidation were not effective inhibitors of hsp70 mRNA accumulation. However, the thiol reducing agent, dithiothreitol, inhibited induction of hsp70 mRNA by NCC. The data suggest that covalent binding and alterations in cellular non-protein thiols serve as signals for activation of pre-existing transcription factors which increase hsp70 gene expression. It is proposed that reactive electrophiles may have a primary effect on protein conformation resulting in activation of the hsp70 gene.
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1713
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Chen Q, Yu K, Stevens J. Regulation of the cellular stress response by reactive electrophiles. The role of covalent binding and cellular thiols in transcriptional activation of the 70-kilodalton heat shock protein gene by nephrotoxic cysteine conjugates. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)35768-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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1714
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Chen Q, Esterbauer H, Jürgens G. Studies on epitopes on low-density lipoprotein modified by 4-hydroxynonenal. Biochemical characterization and determination. Biochem J 1992; 288 ( Pt 1):249-54. [PMID: 1280111 PMCID: PMC1132105 DOI: 10.1042/bj2880249] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Oxidation of human low-density lipoprotein (LDL) was found to be accompanied by the generation of various reactive aldehydes. One of them, 4-hydroxynonenal (HNE), was shown to modify LDL to a form which represents a good model of oxidized LDL (ox-LDL). In order to investigate the epitopes newly formed on HNE-modified LDL, a polyvalent antiserum to HNE-LDL [anti-(HNE-LDL)] was raised in rabbits and the non-specific components were removed with native LDL coupled to CNBr-Sepharose 4B. Competitive fluorescence immunoassay analysis showed that anti-(HNE-LDL) recognized HNE-LDL, copper-oxidized LDL, HNE-albumin and to a lower extent HNE-modified high-density lipoprotein 3 (HNE-HDL3) and ox-HDL3 but not native LDL. A certain degree of cross-reactivity of the antibody with LDLs modified by either hexanal or 2,4-heptadienal was found. No reaction was obtained with LDL labelled with malondialdehyde. From the abilities of HNE-modified poly(L-amino acids) to compete with HNE-LDL for binding to anti-(HNE-LDL), it is postulated that lysine, tyrosine, arginine and histidine are involved in the formation of HNE-derived epitopes on apolipoprotein B (apo B). Using a double-sandwich fluorescence immunoassay [capture antibody: anti-(apo B); detection antibody: anti-(HNE-LDL)] we found that the HNE-derived epitopes were expressed at a far higher degree in ox-LDL and HNE-LDL than in native LDL.
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1715
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Chen Q. [Lead concentrations in urine correlated with cytogenetic damages in workers exposed to lead]. ZHONGHUA YU FANG YI XUE ZA ZHI [CHINESE JOURNAL OF PREVENTIVE MEDICINE] 1992; 26:334-5. [PMID: 1303346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The lead concentrations in urine and the frequency of chromosomal aberrations and sister chromatid exchanges in lymphocytes of 84 printers exposed to lead were investigated. The results demonstrated that the lead concentrations in urine of printers were higher than normal subjects. The frequency of chromosomal aberrations and sister chromatid exchanges increased significantly with the rise of lead concentrations in urine, showing a linear correlation. The regression equations were Y = 1.31 + 9.07 X and Y = 4.24 + 14.91 X respectively. Therefore, the genetic condition of workers who have high lead concentrations in urine should be attended to and appropriate protective measures should be under-taken.
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1716
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Chen Q, Chopp M, Dereski MO, Wilson BC, Patterson MS, Schreiber A, Hetzel FW. The effect of light fluence rate in photodynamic therapy of normal rat brain. Radiat Res 1992; 132:120-3. [PMID: 1410268 DOI: 10.2307/3578343] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This paper reports the effect of incident light fluence rate on the depth to which necrotic lesions are produced by photodynamic therapy (PDT) in the brains of normal Fisher rats. The rats were injected intraperitoneally with Photofrin (12.5 mg kg-1) 48 h prior to PDT with a fixed incident fluence of 35 J cm-2. The treatment was performed at 10, 50, 100, and 200 mW cm-2 and also in a periodic manner (30 s "on" at 100 mW cm-2, 30 s "off"). The depth to which necrosis occurred was determined 24 h after treatment by microscopic examination of tissue sections. No differences were found in the depth to which necrosis was produced by any of the five irradiation schedules. This finding is discussed in the context of other published dose-rate experiments.
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1717
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Chen Q, Pearlman RE, Moens PB. Isolation and characterization of a cDNA encoding a synaptonemal complex protein. Biochem Cell Biol 1992; 70:1030-8. [PMID: 1363622 DOI: 10.1139/o92-147] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A gene encoding a 65-kilodalton antigen of the rat synaptonemal complex, SC65, has been cloned by screening rat testis λgt11 and λZAPII cDNA expression libraries using polyclonal antibodies against rat synaptonemal complex proteins. The longest open reading frame, initiating at an ATG codon in the cDNA, encodes a protein of 431 amino acids, with a relative molecular mass of 50 000. Immunological analysis locates the SC65 gene product on the synaptonemal complex between the pairing faces of the parallel aligned cores of homologous chromosomes in spermatocytes. Of the rat tissues examined, the SC65 gene is transcribed in testis, brain, and heart at similar levels, and in the liver at a much lower level. The DNA sequence extending about 80 base pairs downstream of the translation termination codon has 93% similarity to the identifier sequence present in the rat genome in 1 × 105 – 1.5 × 105 copies and in cDNA clones of precursors of brain-specific mRNAs. The amino acid sequence encoded by the SC65 gene contains an acidic region in the C-terminal domain of the protein, potential glycosylation sites, and at least one possible phosphorylation site. The protein shows no overall similarity to proteins of known function, nor is there similarity to protein sequences present in GenBank or EMBL data bases.Key words: meiosis, synaptonemal complex, antibody, rat testis cDNA library, molecular cloning.
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1718
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Peng HB, Chen Q. Induction of dystrophin localization in cultured Xenopus muscle cells by latex beads. J Cell Sci 1992; 103 ( Pt 2):551-63. [PMID: 1478954 DOI: 10.1242/jcs.103.2.551] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The distribution of dystrophin in Xenopus myotomal muscle cells was examined in conventional and confocal immunofluorescence microscopy. By labeling dissociated single muscle fibers with a monoclonal or a polyclonal antibody against dystrophin, we found that dystrophin is ten times more concentrated at the myotendinous junction (MTJ) than at the extrajunctional sarcolemma. At the MTJ, dystrophin lines the membrane invaginations where myofibrils attach to the membrane. It is colocalized with talin, but is not related to the distribution of acetylcholine receptors (AChRs) which are clustered at the postsynaptic membrane in the vicinity of the MTJ in these fibers. We found that the localization of dystrophin can be induced in cultured Xenopus myotomal muscle cells by treating them with polystyrene latex beads. Dystrophin is discretely localized at the bead-muscle contacts. With electron microscopy, a sarcolemma specialization with all the salient features of the MTJ, including basal lamina-lined membrane invaginations along which myofibrils make attachment. Although these beads also induce clustering of AChRs, the patterns of dystrophin and AChR localization are distinct. The appearance of dystrophin at the bead-contacted sarcolemma is coincident with the development of the membrane invaginations. This, together with its concentration along membrane invaginations at the MTJ in vivo, suggests a role for dystrophin in the formation of this junctional specialization. Since the signal for MTJ development can be presented to cultured muscle cells in a temporally and spatially controlled manner by beads, this system offers a simple model for analyzing the mechanism of this sarcolemma specialization.
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1719
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Abstract
BACKGROUND AND PURPOSE The purpose of this study was to use magnetoencephalography to record magnetic field changes in the brain during middle cerebral artery occlusion. METHODS A direct-current electrocorticogram (two channels) and a direct-current magnetoencephalogram (seven channels) were simultaneously recorded from five rats subjected to middle cerebral artery occlusion for 1-2 hours. RESULTS Direct-current electrocorticographic and direct-current magnetoencephalographic signal deflections were observed after the onset of middle cerebral artery occlusion and occurred repeatedly throughout the ischemic period, with a mean +/- SD time interval of 12 +/- 5 minutes. A one-to-one correspondence of the electrocorticographic and magnetoencephalographic signal deflections was demonstrated. CONCLUSIONS Direct-current magnetoencephalography can provide a new noninvasive technique for studying depolarization and/or spreading depression in focal cerebral ischemia.
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1720
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Chen Q, Xie Y, Chai H. [Effects of calcium channel blocker verapamil on hippocampal kindled seizures induced by coriaria lactone in rabbits]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1992; 23:309-12. [PMID: 1298723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Eighteen fully kindled rabbits, whose epilepsy had been produced by intrahippocampal (i.h.) injections of 2 microliters of diluted solution containing 0.32 or 0.55 micrograms of coriaria lactone (CL), were separated into three groups. One of them was used as the control group. For seizure, all animals were given CL (0.6-1 micrograms/2 microliter i.h.). Ten minutes later, the verapamil (VR) group of six rabbits was treated with VR (1.5 or 2 mg/kg i.m. 2.5 or 5 micrograms/2 microliters i.h.); the normal saline (NS) group (six rabbits) received 0.8 ml/kg (i.m., in the same volume as that of the VR 2 mg/kg injection) or 2 microliters (i.h.) of NS; the control group of six received neither VR nor NS. The experiments were made once every eight days. Hippocampal EEGs of all animals were recorded by telemetric method and their behavior after injection was observed continuously in 4-7 hours. The results of the experiment indicated that the i.h. administration of 2.5 or 5 micrograms/2 microliters of VR is effective on hippocampal kindled seizures induced by CL in rabbits, but the curative effects of the i.m. administration of 1.5 or 2 mg/kg of VR were less notable than those of the i.h. administration.
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1721
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Chen Q, Wilson BC, Dereski MO, Patterson MS, Chopp M, Hetzel FW. Effects of light beam size on fluence distribution and depth of necrosis in superficially applied photodynamic therapy of normal rat brain. Photochem Photobiol 1992; 56:379-84. [PMID: 1438573 DOI: 10.1111/j.1751-1097.1992.tb02174.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The light fluence distributions of 632.8 nm light incident on the exposed surface of normal rat brain in vivo have been measured using an interstitial, stereotactically-mounted optical fiber detector with isotropic response. The dependence of the relative fluence rate on depth and the spatial distribution of fluence were compared for incident beam diameters of 3 and 5 mm. The fluence rate at depth of 1-6 mm along the optical axis within the brain tissue was approximately 70% greater for a 5 mm diameter beam than for a 3 mm beam, at the same incident fluence rate, although the plots of the relative fluence rate vs depth were parallel over the depth range 1-6 mm. The depths of necrosis resulting from photodynamic treatment of brain tissue using the photosensitizer Photofrin and irradiation by 632 nm light with 3 and 5 mm incident beams were also measured. The observed difference in necrosis depths was consistent with the measured difference in fluence. The importance of beam size in photodynamic treatment with small diameter incident light fields is discussed.
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1722
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Ferrini S, Cantoni C, Cambiaggi A, Chen Q, Venzano P, Canevari S, Colnaghi MI, Moretta L. Induction of anti-tumor immune response by bispecific monoclonal antibodies (bimAbs). Pharmacol Res 1992; 26 Suppl 2:146-7. [PMID: 1409285 DOI: 10.1016/1043-6618(92)90638-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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1723
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Chen Q, Florén CH, Nilsson A. Lipoprotein receptor mediated metabolism of [14C]arachidonic acid labeled chylomicron remnants by Hep G2 cells. Lipids 1992; 27:664-8. [PMID: 1336805 DOI: 10.1007/bf02536021] [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: 12/26/2022]
Abstract
During lipolysis of chylomicron triacylglycerol by lipoprotein lipase, arachidonic acid (AA) esters are hydrolyzed at a slower rate than the predominant 16-18 carbon fatty acid esters. The further metabolism of the AA that is hereby enriched in the chylomicron remnant acylglycerols has not been investigated. In the present study, we examined the low density lipoprotein (LDL) dependent and independent metabolism of [14C]AA present in chylomicron remnants in the human hepatoma cell line Hep G2. Mesenteric duct cannulated rats were fed [14C]AA and [3H]cholesterol in corn oil, and the chyle obtained was injected intravenously into hepatectomized rats to form chylomicron remnants labeled with [14C]AA in the triacylglycerol (TG) and with 3H in the cholesteryl ester portion. The remnants were then incubated with Hep G2 cells. The uptake of [14C]AA within 2-4 h was similar to that of [3H]cholesteryl ester. After uptake into the cells, [14C]AA was preferentially incorporated into phospholipids, a high proportion being found in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol. [14C]AA and [3H]cholesteryl ester uptake were influenced to similar extents by factors unknown to regulate the LDL receptor and by an anti-LDL receptor antibody. Addition of compactin thus increased the uptake of [14C]AA by 50% in 4 h and mevalonolactone decreased the uptake by 86%. Using an anti-LDL receptor antibody, 25.0% of [3H]cholesterol/cholesteryl ester and 37.7% of [14C]AA binding to the cells at 4 degrees C were blocked. There was no lipolysis of [14C]TG or [14C]diacylglycerol by lipase secreted into the medium during incubations.(ABSTRACT TRUNCATED AT 250 WORDS)
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1724
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Chen Q, Jahier J, Cauderon Y. Production and cytogenetic analysis of BC1, BC 2, and BC 3 progenies of an intergeneric hybrid between Triticum aestivum (L.) Thell. and tetraploid Agropyron cristatum (L.) Gaertn. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 1992; 84:698-703. [PMID: 24201360 DOI: 10.1007/bf00224171] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/1991] [Accepted: 01/25/1992] [Indexed: 06/02/2023]
Abstract
Intergeneric hybrids between Triticum aestivum cv 'Chinese Spring' and Agropyron cristatum 4x (2n= 5x=35, ABDPP genomes) with a high level of homoeologous meiotic pairing between the wheat chromosomes were backcrossed 3 times to wheat. Pollination of the F1 hybrid with 'Chinese Spring' resulted in 22 BC1 seeds with an average seed set of 1.52%. Five BC1 plants with 39-41 chromosomes were raised using embryo rescue techniques. Chromosome pairing in the BC1 was characterized by a high frequency of multivalent associations, but in spite of this there was no evidence of homoeologous pairing between chromosomes of wheat and those of Agropyron. All of the plants were self sterile. The embryo rescue technique was again essential to produce 39 BC2 plants with chromosome numbers ranging from 37 to 67. The phenomenon of meiotic non-reduction was also observed in the BC3 progenies. In this generation male and female fertility greatly increased, and meiotic pairing was fairly regular. Some monosomic (2n=43) and double monosomic (2n=44) lines were produced. Analysis of these progenies should permit the extraction of the seven possible wheat-Agropyron disomic addition lines including those with the added chromosomes carrying the genes involved in meiotic non-reduction and in suppression of Ph activity.
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1725
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Chen Q, Klein JS, Gamsu G, Webb WR. High-resolution computed tomography of the mammalian lung. Am J Vet Res 1992; 53:1218-24. [PMID: 1497194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
High-resolution computed tomography (HRCT) was performed in 21 isolated animal lungs, from 4 mammalian species (pigs, rabbits, dogs, sheep). Gross and subgross central and peripheral lung morphology was determined by HRCT. Three distinct types of lungs can be identified, principally based on the extent of interlobular septal development; the relationship of major vessels to airways; and the thickness of the visceral pleura. Type-I lung is found in pigs, sheep, and cattle; type-II lung is found in rabbits, dogs, cats, and monkeys; and type-III lung is found in human beings and horses. These mammalian lungs were compared with human lungs. The potential use of HRCT to investigate specific human lung diseases in the aforementioned species also was considered.
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