751
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Yuan S, Trachtenberg J, Mills GB, Brown TJ, Xu F, Keating A. Androgen-induced inhibition of cell proliferation in an androgen-insensitive prostate cancer cell line (PC-3) transfected with a human androgen receptor complementary DNA. Cancer Res 1993; 53:1304-11. [PMID: 8443809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A full length human androgen receptor complementary DNA was introduced into androgen receptor-negative PC-3 cells to determine if androgen sensitivity could be established in this cell line and to assess what influence, if any, androgen exposure would have on the growth of these cells. The androgen receptor complementary DNA was inserted into pSG5 in the region controlled by the SV40 promoter. This construct was cotransfected with pSR1neo into PC-3 cells and stably transfected cells were selected and screened for the expression of the androgen receptor. Active expression of the receptor was demonstrated by Western blotting using a rabbit anti-androgen receptor antiserum and by [3H]methyltrienolone binding to cytosol extracts. Saturation ligand-binding analysis revealed the presence of a single class, high affinity (Kd = 0.122 nM) androgen-binding site in cytosol extracts of transfected cells but not in extracts from mock-transfected cells. In cells expressing the transfected androgen receptor, androgen decreased the proliferation rate and cloning efficiency and induced a more differentiated phenotype. These results demonstrate that PC-3 cells have retained the mechanisms required to respond to the activated androgen receptor and that the loss of androgen sensitivity in these cells is due to the lack of functional androgen receptor. This also provides a technique for determining whether androgen-resistant tumor cells contain functional androgen receptors or whether androgen sensitivity is due to abnormalities in downstream signaling pathways. The apparent androgen-induced decreased malignant state of these transfected cells suggests new directions for the treatment of prostate cancer.
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752
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Xu F, DeFilippi LJ, Ballou DP, Hultquist DE. Hydrogen peroxide-dependent formation and bleaching of the higher oxidation states of bovine erythrocyte green hemeprotein. Arch Biochem Biophys 1993; 301:184-9. [PMID: 8442660 DOI: 10.1006/abbi.1993.1131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The ferric and ferrous forms of bovine erythrocyte green hemeprotein react with hydroperoxides to form higher oxidation state intermediates with absorbance maxima in the Soret region at 426 and 422 nm, respectively. In the absence of an appropriate reductant, these intermediates undergo rapid bleaching reactions. 2,2'-Azinobis(3-ethylbenzthiazoline-6-sulfonic acid) rapidly reduces the intermediate formed by reaction of ferric green hemeprotein with hydrogen peroxide, thereby preventing bleaching and allowing the rate of the intermediate formation to be calculated from the coupled dye oxidation. This rate constant of 70 M-1 s-1 at 23 degrees C is similar to those determined by bleaching and by direct photometric detection of the intermediate. Dihydroriboflavin rapidly reduces the intermediate formed by reaction of ferrous green hemeprotein with hydrogen peroxide, thereby preventing bleaching and allowing the rate of the intermediate formation to be calculated from the coupled dihydroriboflavin oxidation; the rate constant of 2 x 10(4) M-1 s-1 at 23 degrees C is similar to the value calculated by direct detection of the intermediate. The results demonstrate that, in contrast to the reductase activity of its heme-free form, the green heme form of the protein reacts with hydroperoxides to generate highly unstable peroxide complexes.
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753
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Xu F, Taylor RF, McLarney T, Lee LY, Frazier DT. Respiratory load compensation. I. Role of the cerebrum. J Appl Physiol (1985) 1993; 74:853-8. [PMID: 8458806 DOI: 10.1152/jappl.1993.74.2.853] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
This study examines the extent to which the cerebrum and other suprapontine structures modulate the respiratory response to added mechanical resistive loads to breathing. Nine adult cats were anesthetized with thiopental sodium, tracheotomized, and instrumented with diaphragm electromyographic (EMGdi) recording electrodes. Two levels of resistive loads and tracheal occlusion were applied at the onset of inspiration in random order before and after decerebration. The integrated signal of the EMGdi (integral of EMGdi) was used to detect changes in respiratory timing and as an index of respiratory motor drive. The results showed that, compared with intact cats, decerebration did not significantly change baseline values for peak integral of EMGdi, respiratory timing, systemic blood pressure, or arterial blood gases. Although the percent changes in the peak integral of EMGdi elicited by the added loads were still significantly greater than those elicited by unloaded control breaths after decerebration, the magnitude of the responses was significantly attenuated at all load levels compared with the intact preparation. It is concluded that the cerebrum and/or other suprapontine structures provide information that is facilitatory to the respiratory pattern generator with little effect on timing.
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754
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Xu F, Lupu R, Rodriguez GC, Whitaker RS, Boente MP, Berchuck A, Yu Y, DeSombre KA, Boyer CM, Bast RC. Antibody-induced growth inhibition is mediated through immunochemically and functionally distinct epitopes on the extracellular domain of the c-erbB-2 (HER-2/neu) gene product p185. Int J Cancer 1993; 53:401-8. [PMID: 7679090 DOI: 10.1002/ijc.2910530310] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Over-expression of the c-erbB-2 (HER-2/neu) gene product p185 occurs in 30% of breast and ovarian cancers. The p185 protein might serve as a target for serotherapy in that antibodies against different epitopes on the extracellular domain of p185 can inhibit growth of tumor cells in the absence of cellular or humoral effector mechanisms. To define epitopes of functional relevance, 11 monoclonal antibodies (MAbs) were evaluated for their ability to bind to the extracellular domain of p185. Results of competition studies with 125I-labeled and non-labeled antibodies indicated that 10 of 11 epitopes were grouped in a linear array. Antibodies against 7 epitopes inhibited anchorage-independent growth and antibodies against 2 of these epitopes also inhibited anchorage-dependent growth of SKBr3 breast-cancer cells that over-expressed p185. Treatment with antibodies exerted cytotoxic rather than cytostatic effects. When antibodies were used in combination, additive or supra-additive inhibition of anchorage-independent and anchorage-dependent growth was observed between pairs of antibodies. Growth inhibition did not relate to the affinity of the antibody or its isotype. Two antibodies that inhibited both anchorage-dependent and anchorage-independent growth also blocked binding of the HER-2/neu ligand, whereas 5 antibodies that inhibited only anchorage-independent growth had no effect on ligand binding. Inhibition of cell growth did not correlate with internalization of p185 or down-regulation of p185 on the cell surface. Fab fragments of active antibodies could also inhibit anchorage-independent growth of SKBr3. Thus, murine MAbs and their fragments recognized both immunochemically distinct and functionally distinct epitopes on the p185 molecule. Whereas inhibition of anchorage-dependent growth correlated with the ability of antibodies to block ligand binding, inhibition of anchorage-independent growth did not correlate with effects on ligand binding, internalization, cell-surface expression or cross-linking of p185.
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755
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Rodríguez GC, Boente MP, Berchuck A, Whitaker RS, O'Briant KC, Xu F, Bast RC. The effect of antibodies and immunotoxins reactive with HER-2/neu on growth of ovarian and breast cancer cell lines. Am J Obstet Gynecol 1993; 168:228-32. [PMID: 8420332 DOI: 10.1016/s0002-9378(12)90918-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Because HER-2/neu is overexpressed in one third of breast and ovarian cancers, we examined the effect of unconjugated monoclonal antibodies (ID-5, PB-3, TA-1) and an immunotoxin (TA-1-ricin) reactive with this protooncogene on the growth of breast and ovarian cancer cell lines. STUDY DESIGN The tritiated thymidine incorporation assay was used to examine the effect of unconjugated antibodies on proliferation. A limiting dilution clonogenic assay was used to assess the effect of immunotoxin on cellular cytotoxicity. RESULTS Scatchard analysis revealed that OVCA 420, OVCA 429, OVCA 432, and OVCA 433 cells had approximately 10(4) HER-2/neu receptors per cell, whereas the SKOv3 and SKBr3 cell lines expressed 10(5) and 10(6) receptors per cell, respectively. Monoclonal antibody ID-5 caused significant inhibition of tritiated thymidine incorporation in SKBr3, SKOv3, and OVCA 420 cells (p < 0.002). The TA-1-rich immunotoxin significantly inhibited the clonogenic growth of only SKBr3 and SKOv3 cells. CONCLUSION HER-2/neu may be a useful target for immunotherapy with unconjugated antibodies and immunotoxins in ovarian and breast cancers that overexpress this protooncogene.
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756
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Hultquist DE, Xu F, Quandt KS, Shlafer M, Mack CP, Till GO, Seekamp A, Betz AL, Ennis SR. Evidence that NADPH-dependent methemoglobin reductase and administered riboflavin protect tissues from oxidative injury. Am J Hematol 1993; 42:13-8. [PMID: 8416288 DOI: 10.1002/ajh.2830420105] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
NADPH-dependent methemoglobin reductase, first detected in erythrocytes sixty years ago, has subsequently been purified and characterized as a methylene blue reductase and a flavin reductase. The reductase plays no role in methemoglobin reduction under normal conditions, but its activity serves as the basis for the treatment of methemoglobinemia with methylene blue or flavin. On-going studies demonstrate that this cytosolic protein is also present in liver and that its primary structure distinguishes it from other known proteins. The bovine erythrocyte reductase tightly binds hemes, porphyrins, and fatty acids with resulting loss of activity. Pyrroloquinoline quinone serves as a high-affinity substrate of the reductase, suggesting that this naturally-occurring compound may be a physiological substrate. The ability of the reductase to catalyze the intracellular reduction of administered riboflavin to dihydroriboflavin suggested that this system might be exploited to protect tissues from oxidative damage. This hypothesis was supported by our finding that dihydroriboflavin reacts rapidly with Fe(IV)O and Fe(V)O oxidation states of hemeproteins, states that have been implicated in tissue damage associated with ischemia and reperfusion. Preliminary studies demonstrate that, as predicted, administration of low concentrations of riboflavin protects isolated rabbit heart from reoxygenation injury, rat lung from injury resulting from systemic activation of complement, and rat brain from damage caused by four hours of ischemia. Data from these animal studies suggest that flavin therapy holds promise in protecting tissue from the oxidative injuries of myocardial infarction, acute lung injury, stroke, and a number of other clinical conditions.
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757
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Zeng L, Xu F, Ma Q, Chen Y. [Hurler syndrome (a case report)]. YAN KE XUE BAO = EYE SCIENCE 1992; 8:189-92. [PMID: 1306502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A case of Hurler syndrome diagnosed by clinical and laboratory examination is reported. The patient's roentgenograms showed the dystrophies of bones, lace-shaped ribs, boat-shaped cranium, fishhook-shaped forefront protrusion of silla trucica. Corneal opacities and high ocular pressure were found in both eyes. VEP measurement suggested the defects of optic nerve. The authors emphasized that visual electric physiological examinations should be used to estimate the visual functions when the patient's refractive medium is opqaue. The differential diagnosis was also briefly discussed.
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758
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Laver JH, Xu F, Barredo JC, Abboud MR. Effects of radiation and 4-hydroperoxycyclophosphamide on production of G- and GM-CSF by stromal cells. Bone Marrow Transplant 1992; 10:529-33. [PMID: 1283360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effects of in vitro radiation and exposure to 4-hydroperoxycyclophosphamide (4-HC) on the production of G- and GM-CSF by different components of the human hematopoietic microenvironment are described. The marrow microenvironment is composed of fibroblasts, endothelial cells, macrophages, and adipocytes. To study the effects of radiation/4-HC on colony-stimulating factor (CSF) production by stromal cells, confluent layers of umbilical cord endothelial cells (EC), marrow fibroblasts (MF), and heterogeneous adherent layers (HAL) derived from long-term marrow cultures were established. These layers were exposed to radiation up to 3000 cGy and/or 100 mumol/ml of 4-HC and subsequently stimulated with IL-1 beta on day 0, 7, or 14 after radiation/4-HC. Following IL-1 exposure conditioned medium (CM) was collected and G- and GM-CSF levels were measured by ELISA and their ability to support colony formation was assessed. G- and GM-CSF levels after exposure to 4-HC and radiation were 12,460 +/- 172 pg/ml and 2268 +/- 160 pg/ml for EC, 2214 +/- 94 pg/ml and 263 +/- pg/ml for MF, and 3168 +/- 316 pg/ml and 356 +/- 34 pg/ml for HALs, respectively. For each cell group there was no significant difference between levels obtained without exposure and levels after exposure to 4-HC and/or radiation (p > 0.6). Comparison of levels obtained from different cell groups showed significant differences with EC media being the highest (p < 0.0001). To test the activity of these measured factors, CM of different sources was used in colony assays of CD 34+ cord blood progenitors.(ABSTRACT TRUNCATED AT 250 WORDS)
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759
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Xu F, Sato M, Spellman MJ, Mitchell RA, Severinghaus JW. Topography of cat medullary ventral surface hypoxic acidification. J Appl Physiol (1985) 1992; 73:2631-7. [PMID: 1490980 DOI: 10.1152/jappl.1992.73.6.2631] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The topographic relationship between previously identified medullary ventral surface respiratory chemosensitive regions and brain surface extracellular fluid (ECF) acid production during acute hypoxia was explored in anesthetized, paralyzed, and artificially ventilated cats. Glass pH electrodes (0.8-mm diam, sheathed in stainless steel tubing) were mounted in mechanical contact with surfaces of medullary surface or adjacent pyramids, pons, spinal cord, or parietal cortex. Isocapnic hypoxia of 5 min [at arterial O2 saturation (SaO2) = 48 +/- 10%] reduced pH over rostral (Mitchell) and caudal (Loeschcke) areas by 0.12 +/- 0.09 and 0.07 +/- 0.04, respectively (n = 10, P < 0.05). Change in pH (delta pH) was proportional to desaturation with slopes 100 delta pH/delta SaO2 of 0.45 (rostral) and 0.20 (caudal) (R = 0.91 and 0.88, respectively). pH drop usually began within 3 min of hypoxia, became stable between 5 and 15 min, began to rise within 2 min of reoxygenation, and returned to control within 10 min. During equally hypoxic tests, intermediate area (Schläfke), pons, and spinal cord surfaces showed no significant acid shift. Parietal cortex ECF pH dropped more slowly but steadily by 0.079 +/- 0.034 during 20 min at SaO2 = 50% after a small but significant initial alkaline shift, and acidification of cortical surface continued for > 5 min after reoxygenation. We conclude that medullary ventral chemosensitive regions produce more lactic acid during hypoxia than neighboring brain surfaces.(ABSTRACT TRUNCATED AT 250 WORDS)
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760
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Xu F, Kitzerow H, Crooker PP. Electric-field effects on nematic droplets with negative dielectric anisotropy. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 46:6535-6540. [PMID: 9907962 DOI: 10.1103/physreva.46.6535] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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761
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Xu F, Bonanno A. Ar L-shell Auger-electron emission in ion-solid collisions. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:11405-11414. [PMID: 10003025 DOI: 10.1103/physrevb.46.11405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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762
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Schecker J, Berger A, Das J, Dutta S, Gwinner G, Holbrow CH, Kühl T, Lauritsen T, Sprouse GD, Xu F. Optical isotope shifts of stable hafnium atoms in a resonance cell on-line with a heavy-ion accelerator. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 46:3730-3734. [PMID: 9908563 DOI: 10.1103/physreva.46.3730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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763
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Abboud M, Xu F, LaVia M, Laver J. Study of early hematopoietic precursors in human cord blood. Exp Hematol 1992; 20:1043-7. [PMID: 1281782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Human cord blood is a source of transplantable stem cells. These stem cells express the antigen CD34, are resistant to treatment with 4-hydroperoxycyclophosphamide (CD34+/4-HCres), and do not give rise to colonies when plated in clonogenic assays. We studied the number of CD34+ cells present in cord blood and developed a two-step assay for early precursors (pre-colony-forming units, pre-CFU) capable of giving rise to committed progenitors. In this assay CD34+/4-HCres cord blood cells were cultured in suspension with different growth factors. After 7 days in suspension the remaining cells were plated in clonogenic assays, for granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), and mixed lineage colony-forming units (CFU-MIX), in the presence of pure factors or a combination of recombinant human (rh) interleukin 3 (IL-3) and medium conditioned by the PU34 primate cell line. Pre-CFU for all precursors were identified. These pre-CFU developed into committed progenitors in response to rhIL-3. The combinations of rhIL-3 plus rh interleukin 1 (IL-1) or rhIL-3 plus rh interleukin 6 (IL-6) did not enhance recovery of progenitors. The developing CFU-GM were responsive to rh granulocyte-macrophage colony-stimulating factor (GM-CSF) and rh granulocyte colony-stimulating factor (G-CSF) but much less so to rhIL-3. BFU-E and CFU-MIX developed in suspension but could only be detected when cells were replated in the presence of a combination of rhIL-3 and PU34 but not rhIL-3 alone. This assay may be useful in evaluating the number of early hematopoietic precursors present in cord blood samples and in defining growth factor combinations that could enhance hematopoietic recovery after cord blood stem cell transplants.
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764
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Wang Z, Xu F, An S. [Chemical constituents from the root bark of Dictamnus dasycarpus Turcz]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1992; 17:551-2, 576. [PMID: 1292497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Rutaevin was isolated from the root bark of Dictamnus dasycarpus. It has been obtained from genus Dictamnus for the first time.
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765
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Xu F, Mandarino N, Zoccali P, Bonanno A. Al atomic Auger electron emission from low-keV-ion-bombarded Al surfaces. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 46:2613-2617. [PMID: 9908420 DOI: 10.1103/physreva.46.2613] [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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766
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Zhuang J, Zhang M, Zeng Z, Xu F, Han T, Hu S, Sun Y. [The use of 6-flavor Rehmannia decoction with additives in the prevention of ototoxic deafness induced by gentamicin in guinea pigs]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1992; 17:496-9, inside backcover. [PMID: 1482540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The purpose of this study is to discuss the effects of the Chinese medicine six-flavor Rehmannia Decoction with additives on preventing deafness induced by gentamicin (GM) in guinea pig by means of testing the thresholds of Preyer's reflex (PR) cochlear microphonic potential (CM), action potential of the auditory nerve (N1) and scanning electron microscope of inner ear (SEM). The results showed that the medicine is effective in reducing the ototoxic effect of GM on inner ear.
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767
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Xu F, Hultquist DE. Bovine erythrocyte glutathione S-transferase: purification, inhibition, and complex formation. BIOCHEMISTRY INTERNATIONAL 1992; 27:265-74. [PMID: 1503563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Glutathione S-transferase has been purified from bovine erythrocytes by affinity chromatography. The enzyme has an isoelectric point of 7.2, behaves as a 48-kDa protein composed of two identical subunits, and has an N-terminal sequence of PPYTIVYFPVQGR?EAMRMLL. This sequence, the amino acid composition, and the kinetic parameters suggest that the enzyme belongs to the pi-class of transferases. Hemins, porphyrins, and fatty acids form complexes with the enzyme and serve as effective inhibitors. Treatment of the transferase with N-ethylmaleimide, 3-amino-1,2,4-triazole, diethyl pyrocarbonate, or 2,3-butanedione inhibits transferase activity without altering tetrapyrrole binding. The role of the complexation and inhibition of glutathione S-transferase in erythroid metabolism has yet to be elucidated.
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768
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Baragiola RA, Alonso EV, Oliva A, Bonnano A, Xu F. Fast electrons from slow atomic collisions. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 45:5286-5288. [PMID: 9907622 DOI: 10.1103/physreva.45.5286] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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769
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Xu F, Quandt KS, Hultquist DE. Characterization of NADPH-dependent methemoglobin reductase as a heme-binding protein present in erythrocytes and liver. Proc Natl Acad Sci U S A 1992; 89:2130-4. [PMID: 1549573 PMCID: PMC48610 DOI: 10.1073/pnas.89.6.2130] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
An NADPH-dependent reductase, first shown in the 1930s to catalyze the methylene blue-dependent reduction of methemoglobin in erythrocytes, has now been characterized as a high-affinity heme-binding protein and has been detected in liver. Highly purified bovine erythrocyte reductase binds protohemin to form a 1:1 complex with a Kd of 7 nM. Binding of protohemin completely inhibits reductase activity. Other tetrapyrroles and fatty acids also bind to the reductase and inhibit its activity. Protoporphyrin, hematoporphyrin, and coproporphyrin form 1:1 complexes with Kd values ranging from 1 to 5 microM. The inhibition constants for a number of saturated and unsaturated fatty acids range from 6 to 52 microM. A protein that is immunologically cross-reactive to the reductase has been detected in the cytosolic fractions of bovine and rat liver and of bovine, rat, rabbit, and human erythrocytes. By immunoblot analysis, the bovine liver and erythrocyte proteins appear identical in size, as do the rat liver and erythrocyte proteins. The concentration of the protein in bovine erythrocytes has been estimated by quantitative immunoblotting to be 10 microM. The detection of this protein in liver cells, the demonstration of its binding properties, and its weak reductase activity bring into question the long-held belief that this is uniquely an erythrocyte protein and that it functions as a reductase.
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770
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771
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Xu F, Hultquist DE. Coupling of dihydroriboflavin oxidation to the formation of the higher valence states of hemeproteins. Biochem Biophys Res Commun 1991; 181:197-203. [PMID: 1659807 DOI: 10.1016/s0006-291x(05)81401-9] [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: 12/28/2022]
Abstract
The reactions between hydrogen peroxide and hemeproteins have been coupled to the oxidation of dihydroriboflavin so as to provide a simple method for measuring the rate constant of hemeprotein peroxidation. Dihydroriboflavin rapidly reduces the higher oxidation states of iron and the hydroxy radicals which are the products of the hemeprotein/hydrogen peroxide reaction. The rapid reduction of these highly reactive compounds prevents the hemeproteins from undergoing irreversible chemical modifications and thus allows the kinetics of peroxidation to be studied. The rate constants at pH 7.2 and 23 degrees C for the peroxidation of horseradish peroxidase, myoglobin, and ferrocytochrome c are found to be 6.2 x 10(6), 7.5 x 10(4), and 8 x 10(3)M-1s-1, respectively. These studies suggest that reduced riboflavin might efficiently protect cells from oxidative damage such as that occurring in inflammation and reperfusion injury.
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772
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Quandt KS, Xu F, Chen P, Hultquist DE. Evidence that the protein components of bovine erythrocyte green heme binding protein and flavin reductase are identical. Biochem Biophys Res Commun 1991; 178:315-21. [PMID: 2069570 DOI: 10.1016/0006-291x(91)91816-u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Bovine erythrocyte green heme binding protein and bovine erythrocyte flavin reductase have been isolated in highly purified forms and subjected to amino acid analysis and N-terminal amino acid sequence analysis. The two proteins possess similar amino acid compositions and identical N-terminal amino acid sequences. Moreover, the two proteins are immunochemically cross-reactive and are indistinguishable when compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by double diffusion technique. This study provides evidence that the protein components of bovine erythrocyte green heme binding protein and flavin reductase are identical.
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773
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Bonanno A, Xu F, Camarca M, Siciliano R, Oliva A. Angle-resolved Auger study of 10-keV Ar+-ion-induced Si LMM atomic lines. PHYSICAL REVIEW. B, CONDENSED MATTER 1990; 41:12590-12598. [PMID: 9993733 DOI: 10.1103/physrevb.41.12590] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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774
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Zhai Y, Xu L, Xu F, Liu Z. TCM treatment of male infertility due to seminal abnormality--a clinical observation of 82 cases. J TRADIT CHIN MED 1990; 10:26-9. [PMID: 2362459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
82 male patients of infertility due to seminal abnormality were treated by Ju Jing Powder with a total effective rate of 85.4%. The sperm density in seminal fluid, the total sperm number in a single ejaculation and the activity rate of sperms markedly improved as compared with those before treatment (P less than 0.01), especially the grading of sperm motility.
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775
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Xu F. [Study on forecasting local rubella outbreaks in Hangzhou city proper by serologic method]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 1990; 11:20-3. [PMID: 2182194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Rubella outbreaks were proved by the rubazyme M test (Abbott) and rubella haemagglutination inhibition test in Hangzhou city in 1987. On the basis of these and previous immune surveillance in human population, we predict that epidemic of rubella will also occur in recent two years. Rubella IgM antibody was detected by enzyme immunoassay using commercially available Rubazyme-M Diagnostic Kit (Abbott Laboratories). It was detected within 0-66 days after eruption and detection rate was the highest between 5th and 14th day of onset. The coincidence rate of enzyme immunoassay and HAI tests for rubella diagnosis was 90.3%, and false negative rate of enzyme immunoassay was 9.7%. Besides, the importance of differentiating measles from rubella and diagnostic criteria of HAI test for rubella were discussed.
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776
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Aldao CM, Vitomirov IM, Xu F, Weaver JH. Disruption, atom distributions, and energy levels for Ge/GaAs(110), Ge/InP(110), and Ge/InSb(110) heterojunctions. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:3711-3719. [PMID: 9992341 DOI: 10.1103/physrevb.40.3711] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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777
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Trafas BM, Xu F, Vos M, Aldao CM, Weaver JH. Metal/GaP(110) interface formation: Ti, Pd, Ag, and Au adatom deposition. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:4022-4029. [PMID: 9992376 DOI: 10.1103/physrevb.40.4022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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778
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Vos M, Xu F, Anderson SG, Weaver JH, Cheng H. Photoemission studies of interface chemistry and Schottky barriers for ZnSe(100) with Ti, Co, Cu, Pd, Ag, Au, Ce, and Al. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:10744-10752. [PMID: 9947884 DOI: 10.1103/physrevb.39.10744] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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779
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Xu F, Vos M, Weaver JH. Influence of Au overlayers on valence-band offsets for buried CaF2/Si(111) interfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:8008-8011. [PMID: 9947495 DOI: 10.1103/physrevb.39.8008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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780
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Anderson SG, Xu F, Vos M, Weaver JH, Cheng H. Schottky-barrier formation and atomic mixing at Au/ZnSe(100) and Co/ZnSe(100) interfaces with Co and Au interlayers. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:5079-5090. [PMID: 9948896 DOI: 10.1103/physrevb.39.5079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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781
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Trafas BM, Vitomirov IM, Aldao CM, Gao Y, Xu F, Weaver JH, Partin DL. Cr, Co, Pd, Au, and In overlayers on PbS(100): Adatom interactions and interface formation. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:3265-3273. [PMID: 9948628 DOI: 10.1103/physrevb.39.3265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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782
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Xu F, Vos M, Weaver JH, Cheng H. Interface dipoles, surface work functions, and Schottky-barrier formation at Au/ZnSe(100) interfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:13418-13421. [PMID: 9946327 DOI: 10.1103/physrevb.38.13418] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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783
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Shi JF, Liao QJ, Xu F. [Synthesis of 21-chloro-danazol and its delta 6-analogue]. YAO XUE XUE BAO = ACTA PHARMACEUTICA SINICA 1988; 23:860-2. [PMID: 3257044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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784
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Xu F, Vos M, Sullivan JP, Atanasoska L, Anderson SG, Weaver JH, Cheng H. Band-gap discontinuities for Ge/ZnSe(100) and Si/ZnSe(100): A photoemission study. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:7832-7835. [PMID: 9945519 DOI: 10.1103/physrevb.38.7832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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785
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Hill DM, Xu F, Lin Z, Weaver JH. Atomic distributions across metal-III-V-compound-semiconductor interfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:1893-1900. [PMID: 9946475 DOI: 10.1103/physrevb.38.1893] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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786
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Xu F, Hill DM, Lin Z, Anderson SG, Shapira Y, Weaver JH. Temperature-dependent reaction and atomic redistribution for Ti/GaAs(100) interfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 37:10295-10300. [PMID: 9944464 DOI: 10.1103/physrevb.37.10295] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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787
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Aldao CM, Vitomirov IM, Xu F, Weaver JH. 3d transition metals on InP(110): A comparative study of reactive interface evolution. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 37:6019-6026. [PMID: 9943831 DOI: 10.1103/physrevb.37.6019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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788
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Shi JF, Xu F, Liao QJ. [Synthesis of danazol derivatives and steroidal-3-oxo-2 alpha-carbonitriles]. YAO XUE XUE BAO = ACTA PHARMACEUTICA SINICA 1988; 23:148-51. [PMID: 3188923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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789
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Xu F, Fei RZ, Ding GY, Wang ZD, Shen FX. Role of EAC1q4 in C1a transfer reaction (C1aTR) and further information on the nature of the EAC1q4 site. COMPLEMENT (BASEL, SWITZERLAND) 1988; 5:174-9. [PMID: 2849524 DOI: 10.1159/000463054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The complement intermediates EAC1, EAC4, and EAC1q4 were prepared with guinea pig, porcine, as well as human complement. EAC4 and EAC1q4 were made from EC4 and EAC14 respectively. The C1a transfer reaction (C1aTR), the second step of Borsos' C1a fixation and transfer test, was carried out with various combinations of these intermediates. It was found that the EAC1q4, instead of the EAC4, was the C1a acceptor, and the C1rs subcomponents rather than the whole C1 molecule should have to transfer in the C1aTR. The EAC41 derived from EC4 generated no EAC1q4 in EDTA medium as the EAC14 did. This presented evidence for the joining of C4 to A in the EAC1q4 site.
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790
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Shapira Y, Boscherini F, Capasso C, Xu F, Hill DM, Weaver AJ. Au/InSb(110) interface profiles from synchrotron-radiation and polar-angle-dependent x-ray photoemission. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:7656-7659. [PMID: 9942545 DOI: 10.1103/physrevb.36.7656] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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791
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Lexa D, Savéant J, Xu F, Momenteau M. Ligation of iron(II) by bromide ions in the redox chemistry of iron porphyrins. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/0022-0728(87)80314-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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792
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Lin Z, Xu F, Weaver JH. Surface segregation at metalndashIII-V-compound-semiconductor interfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:5777-5783. [PMID: 9942255 DOI: 10.1103/physrevb.36.5777] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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793
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Xu F, Lin Z, Hill DM, Weaver JH. Temperature-dependent interface evolution for Ti/GaAs(100) and Cr/GaAs(100). PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:6624-6630. [PMID: 9942377 DOI: 10.1103/physrevb.36.6624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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794
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Xu F, Aldao CM, Vitomirov IM, Lin Z, Weaver JH. Direct evidence of the onset of In surface segregation for Co/InP(110). PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:3495-3498. [PMID: 9943276 DOI: 10.1103/physrevb.36.3495] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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795
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Yeh WJ, Chen L, Xu F, Bi B, Yang P. Persistent current in Ba-Y-Cu-O in liquid nitrogen. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:2414-2416. [PMID: 9943117 DOI: 10.1103/physrevb.36.2414] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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796
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Xu F, Lin Z, Hill DM, Weaver JH. Temperature-dependent reaction and buried-interface movement for Ti/GaAs(100) and Cr/GaAs(100). PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 35:9353-9356. [PMID: 9941352 DOI: 10.1103/physrevb.35.9353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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797
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Xu F, Shapira Y, Hill DM, Weaver JH. Atom profiles of interfaces with polar-angle-dependent photoemission: Au/GaAs(100). PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 35:7417-7422. [PMID: 9941044 DOI: 10.1103/physrevb.35.7417] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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798
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Xu F, Joyce JJ, Ruckman MW, Chen H, Boscherini F, Hill DM, Chambers SA, Weaver JH. Epitaxy, overlayer growth, and surface segregation for Co/GaAs(110) and Co/GaAs(100)-c(82). PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 35:2375-2384. [PMID: 9941686 DOI: 10.1103/physrevb.35.2375] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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799
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Chambers SA, Hill DM, Xu F, Weaver JH. Silicide formation at the Ti/Si(111) interface: Diffusion parameters and behavior at elevated temperatures. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 35:634-640. [PMID: 9941446 DOI: 10.1103/physrevb.35.634] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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800
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Chambers SA, Xu F, Chen HW, Vitomirov IM, Anderson SB, Weaver JH. Simultaneous epitaxy and substrate out-diffusion at a metal-semiconductor interface: Fe/GaAs(001)-c(8 x 2). PHYSICAL REVIEW. B, CONDENSED MATTER 1986; 34:6605-6611. [PMID: 9939299 DOI: 10.1103/physrevb.34.6605] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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