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Zhou F, Lu J, Zhu X, Mao H, Yang H, Geng D, Xu Y. Effects of a Cannabinoid Receptor 2 Selective Antagonist on the Inflammatory Reaction to Titanium Particles In Vivo and In Vitro. J Int Med Res 2010; 38:2023-32. [PMID: 21227006 DOI: 10.1177/147323001003800616] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Wear particle-induced inflammation is a major factor contributing to aseptic loosening in peri-prosthetic tissue. The effects of cannabinoid receptor 2 (CB2) on wear particle-induced inflammation remain unclear. Reverse transcription–polymerase chain reaction and enzyme-linked immunosorbent assay were used to assess the effects of a CB2-selective antagonist, AM630, on regulation of the inflammatory reaction and production of pro-inflammatory cytokines in response to in vitro and in vivo stimulation with titanium particles. In vitro studies, in a model for pre-osteoclast-like cells, demonstrated that AM630 inactivation of CB2 profoundly inhibited interleukin (IL)-1β and tumour necrosis factor (TNF)-α production by RAW264.7 cells stimulated with titanium particles. In vivo findings in a murine air-pouch model of titanium-induced inflammatory osteolysis indicated that AM630 reduced titanium-induced tissue inflammation, seen as a reduction in pouch membrane thickness, inflammatory infiltration and levels of the pro-inflammatory cytokines IL-1β and TNF-α. Thus, inactivation of CB2 by AM630 inhibited the titanium particle-induced inflammatory reaction by reducing pro-inflammatory cytokines in vitro and in vivo.
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Sun S, Zhang G, Geng D, Chen Y, Li R, Cai M, Sun X. Titelbild: A Highly Durable Platinum Nanocatalyst for Proton Exchange Membrane Fuel Cells: Multiarmed Starlike Nanowire Single Crystal (Angew. Chem. 2/2011). Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201006533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Sun S, Zhang G, Geng D, Chen Y, Li R, Cai M, Sun X. Cover Picture: A Highly Durable Platinum Nanocatalyst for Proton Exchange Membrane Fuel Cells: Multiarmed Starlike Nanowire Single Crystal (Angew. Chem. Int. Ed. 2/2011). Angew Chem Int Ed Engl 2010. [DOI: 10.1002/anie.201006533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sun S, Zhang G, Geng D, Chen Y, Li R, Cai M, Sun X. A Highly Durable Platinum Nanocatalyst for Proton Exchange Membrane Fuel Cells: Multiarmed Starlike Nanowire Single Crystal. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201004631] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Sun S, Zhang G, Geng D, Chen Y, Li R, Cai M, Sun X. A Highly Durable Platinum Nanocatalyst for Proton Exchange Membrane Fuel Cells: Multiarmed Starlike Nanowire Single Crystal. Angew Chem Int Ed Engl 2010; 50:422-6. [DOI: 10.1002/anie.201004631] [Citation(s) in RCA: 334] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Zhang Y, Dong R, Fan H, Li S, Geng D. Hypothalamus syndrome in opticospinal multiple sclerosis. AJNR Am J Neuroradiol 2010; 32:E153-5. [PMID: 21051517 DOI: 10.3174/ajnr.a2278] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This study describes a case of a patient with OSMS who presented with somnolence, periodic fever, memory impairment, and amenorrhea. Serum prolactin levels were found to be higher than normal. MR imaging showed a bilateral involvement of the hypothalamus. The clinical presentation, laboratory examination, and MR imaging findings suggested a diagnosis of hypothalamus syndrome in this patient.
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Wu J, Yang H, Qiu Z, Zhang Q, Ding T, Geng D. Effect of combined treatment with methylprednisolone and Nogo-A monoclonal antibody after rat spinal cord injury. J Int Med Res 2010; 38:570-82. [PMID: 20515570 DOI: 10.1177/147323001003800219] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The purpose of this study was to investigate the effects of combination therapy with methylprednisolone (MP) and Nogo-66 antagonistic peptide (NEP1-40) on morphological and functional recovery in adult rats subjected to thoracic compression spinal cord injury (SCI). Animals were randomized into four groups: a trauma control group, an MP group, an NEP1-40 group, and a combined treatment group. The inflammatory reaction, neuronal and oligodendrocyte survival, and ultrastructure were assessed at the injury site. Functional analysis was also performed using Basso, Beattie and Bresnahan (BBB) scoring. Rat behaviour was evaluated regularly up to week 4. NEP1-40 did not alter the beneficial effect of MP on haematogenous inflammatory cell infiltration, while combined treatment resulted in greater neuronal and oligodendrocyte survival compared with monotherapy or control. Combination therapy resulted in better locomotor scores. These results in a clinically-relevant SCI model showed that significant neuroprotection can be obtained by combining an initial acute IV injection of MP with continuously infused NEP1-40.
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Sun S, Zhang G, Geng D, Chen Y, Banis M, Li R, Cai M, Sun X. Inside Cover: Direct Growth of Single-Crystal Pt Nanowires on Sn@CNT Nanocable: 3D Electrodes for Highly Active Electrocatalysts (Chem. Eur. J. 3/2010). Chemistry 2010. [DOI: 10.1002/chem.201090002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Nie K, Li L, Li X, Geng D, Zhang Q, Tuo M, Xu P, Chen J. In Situ Fiber-Optic Dissolution Assisted by a Mathematical Separation Model of Dynamic Three-Wavelength K-Ratio Spectrophotometry. DISSOLUT TECHNOL 2010. [DOI: 10.14227/dt1701210p15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Nie K, Li X, Geng D, Zhang Q, Tuo M, Xu P, Chen J. In Situ Fiber-Optic Dissolution Assisted by a Mathematical Separation Model of Dynamic Three-Wavelength K-Ratio Spectrophotometry. DISSOLUT TECHNOL 2010. [DOI: 10.14227/dt170210p15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Sun S, Zhang G, Geng D, Chen Y, Banis M, Li R, Cai M, Sun X. Direct Growth of Single-Crystal Pt Nanowires on Sn@CNT Nanocable: 3D Electrodes for Highly Active Electrocatalysts. Chemistry 2009; 16:829-35. [DOI: 10.1002/chem.200902320] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Geng D, Zhang S, Lan J. [Analysis on chemical components of volatile oil and determination of thymoquinone from seed of Nigella glandulifera]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 2009; 34:2887-2890. [PMID: 20209952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
OBJECTIVE To analysis chemical components of volatile oil from the seed of Nigella glandulifera (NG), comparing them with those from the seed of foreign N. sativa (NS) and N. damascene (ND), and to quantify thymoquinone in the volatile oil extracted by hydrodistillation (HD) from the seed of NG. METHOD The volatile oil was extracted by supercritical CO2 extraction (SFE-CO2 ) and HD from the seed of NG and its chemical components was analysed by GC-MS, the relative percentage of components were determined by peak aera normalization method and compare with those of the seed of NS and ND. The content of the thymoquinone in the volatile oil was determined by one point external standard method. RESULT In terms of the volatile compounds, p-cymene is the major component of NG and NS, their relative percentage contents are 33.75% and 61.48%, respectively. beta-Elemene is the major component of ND, its relative percentage content is 73.24%. The relative percentage contents of thymoquinone are 3.73% (HD), 3.80% and 0.08% in NG, NS and ND, respectively. Linoleic acid is a major component of volatile oil by SFE-CO2 in NG, but its content of p-cymene is lower. The absolute percentage content of thymoquinone is 1.58% by HD in volatile oil of NG. CONCLUSION There are comparatively large differences of volatile components in NG, NS and ND.
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Tornetta M, Fisher D, O'Neil K, Geng D, Schantz A, Brigham-Burke M, Lombardo D, Fink D, Knight D, Sweet R, Tsui P. Isolation of human anti-idiotypic antibodies by phage display for clinical immune response assays. J Immunol Methods 2007; 328:34-44. [PMID: 17888945 DOI: 10.1016/j.jim.2007.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 05/23/2007] [Accepted: 08/02/2007] [Indexed: 11/29/2022]
Abstract
The clinical development of therapeutic proteins requires assays that measure the pharmacokinetic (PK) profile of, and the potential immune response (IR) to, the protein agent. Each assay requires reagents that are highly specific for the therapeutic protein. For therapeutic monoclonal antibodies, anti-CDR-specific, or anti-idiotypic (anti-id), antibodies are an ideal class of reagents suitable for these assays because of their high specificity and affinity to the drug antibody. We generated anti-ids to two human antibodies by antibody phage display using the MorphoSys HuCAL GOLD Fab library. To selectively target the CDR regions, serum and a framework-matched mAb were included as competitors during the phage selection process. Panels of CDR-specific Fabs, with low to sub-nM affinities, were isolated against both targets. The CDR specificity of these Fabs was shown by their lack of binding to a framework-matched control mAb and by competition of this binding with the soluble antigens of the respective therapeutic mAb targets. The candidate anti-id Fabs were able to detect both immobilized and soluble target Ab without being affected by serum, a requirement for both PK assay and the IR bridging assay format. Combinations of the Fabs for PK detection assays were identified by pairwise binding studies, although the pair for one target mAb lacks the desired sensitivity for PK assays. To evaluate their potential as anti-drug antibodies (ADAs), the best Fabs for one of the targets were converted and produced as the required bivalent human mAbs. In comparison to rodent mAbs and primate polyclonal serum, the phage display derived human mAbs were equally effective as reference standards. Our results demonstrate that competition-based phage selection can be an effective method for the isolation of anti-idiotypic antibodies for PK and IR assay development, and in this latter case, overcome limitations of current methods using rodent derived anti-ids.
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Ren FL, Guo X, Zhang RJ, Wang SJ, Zuo H, Zhang ZT, Geng D, Yu Y, Su M. Effects of selenium and iodine deficiency on bone, cartilage growth plate and chondrocyte differentiation in two generations of rats. Osteoarthritis Cartilage 2007; 15:1171-7. [PMID: 17490897 DOI: 10.1016/j.joca.2007.03.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 03/16/2007] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The purpose of the current study was to investigate the roles of combined selenium and iodine deficiency in bone development as a possible experimental model of Kashin-Beck osteoarthropathy. METHODS Sprague-Dawley rats (n=48) were randomly divided into selenium deficiency (-Se+I), iodine deficiency (+Se-I), combined selenium and iodine deficiency (-Se-I), and selenium and iodine sufficient (+Se+I) groups. Growth of bone and cartilage, and the expression of type X collagen (ColX) and parathyroid hormone-related peptide (PTHrP) were measured in two generations of rats (F(0) and F(1)). RESULTS The tibial length in -Se-I rats was significantly shorter in F(1) generation. In +Se-I of F(1) rats, the thickness of the growth plate cartilage, and the proliferative zone was smaller, while in -Se-I rats the growth plate, and the proliferative and hypertrophic zones were also thinner in F(1) generation. In articular cartilage, ColX expression was increased in the deep zone in -Se-I rats of F(0) generation, and in -Se+I, +Se-I and -Se-I rats of F(1) generation. PTHrP expression was increased in the middle zone of -Se+I, +Se-I and -Se-I rats of both F(0) and F(1) generations. In the growth plate cartilage, ColX and PTHrP were expressed in the hypertrophic zone. ColX expression was significantly weaker in -Se+I and -Se-I rats in both F(0) and F(1) generations, while PTHrP expression was stronger in -Se+I, +Se-I and -Se-I rats in both F(0) and F(1) animals. CONCLUSIONS Combined selenium and iodine deficiency impaired the growth of bone and cartilage. The changes in the expression of ColX and PTHrP induced by combined selenium and iodine deficiency were compatible to measurements of ColX and PTHrP in Kashin-Beck osteoarthropathy.
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Geng D, Chen L, Lu G. pH induced size-selected synthesis of PtRu nanoparticles, their characterization and electrocatalytic properties. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.molcata.2006.09.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tang Z, Geng D, Lu G. Size-controlled synthesis of colloidal platinum nanoparticles and their activity for the electrocatalytic oxidation of carbon monoxide. J Colloid Interface Sci 2005; 287:159-66. [PMID: 15914161 DOI: 10.1016/j.jcis.2005.01.096] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2004] [Revised: 01/25/2005] [Accepted: 01/25/2005] [Indexed: 11/30/2022]
Abstract
Using polyvinylpyrrolidone (PVP) as a stabilizing agent, stable colloidal solutions of platinum nanoparticles of different size distributions have been prepared by reducing H2PtCl6 with hydrogen. The UV-vis adsorption peaks at 258 nm due to the adsorption of Pt(IV) species disappear completely, indicating that the Pt(IV) species has been used up and colloidal Pt has been formed. The electrodes have been prepared from aqueous Pt colloids and glassy carbon (GC). The effect of platinum particle size of Pt/GC catalyst electrode on the electrocatalytic oxidation of carbon monoxide has been investigated. The voltammetry shows that a higher potential is needed for the oxidation of absorbed carbon monoxide with a decrease of the platinum particle size for particle sizes larger than 1 nm. But for particle sizes smaller than 1 nm, the potential remains constant while the activity decreases with decreasing the size. The snowlike, well-dispersed, and highly ordered platinum nanoparticles demonstrate high activity in the oxidation reaction of carbon monoxide. The reason may be due to the geometric structure of platinum nanoparticles.
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Yu Q, Ma L, Jing S, Xu Y, Geng D. [Clinic significance of nm23, collage IV and PCNA expression in non-small cell lung cancer]. ZHONGGUO FEI AI ZA ZHI = CHINESE JOURNAL OF LUNG CANCER 2001; 4:469-70. [PMID: 21106162 DOI: 10.3779/j.issn.1009-3419.2001.06.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND To study the significance of nm23, collagen IV and PCNA expressions in non-small cell lung cancer. METHODS Expressions of the nm23, collagen IV and PCNA in 84 cases of non-small cell lung cancer were examined with SP immunohistochemical technique. Of the 84 cases, there were squamous cell carcinoma 42, adenocarcinoma 42, stage I 27, stage II 24, stage III 24, and stage IV 9. Statistical analysis was performed with Chi-Square test. RESULTS Expressions of the nm23, collagen IV and PCNA in 84 cases of non-small cell lung cancer were 60. 7% ( 51/ 84) , 75. 0% ( 63/ 84) and 53. 6% ( 45/ 84) respectively. There was negative correlation between the lymph node metastasis and the expressions of nm23 and collagen IV in squamous cell carcinoma, and the expressions of collagen IV and PCNA were associated with tumor differentiation. No correlation was found between TNM stage and expressions of nm23, collagen IV and PCNA. CONCLUSIONS The results indicate that nm23, collagen IV and PCNA participate the modulation of metastasis of non-small cell lung cancer and that they may be used to evaluate the potential of metastasis.
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Lee RS, Yamada K, Womer KL, Pillsbury EP, Allison KS, Marolewski AE, Geng D, Thall AD, Arn JS, Sachs DH, Sayegh MH, Madsen JC. Blockade of CD28-B7, but not CD40-CD154, prevents costimulation of allogeneic porcine and xenogeneic human anti-porcine T cell responses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:3434-44. [PMID: 10706740 DOI: 10.4049/jimmunol.164.6.3434] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Despite increasing use of swine in transplantation research, the ability to block costimulation of allogeneic T cell responses has not been demonstrated in swine, and the effects of costimulatory blockade on xenogeneic human anti-porcine T cell responses are also not clear. We have compared the in vitro effects of anti-human CD154 mAb and human CTLA4IgG4 on allogeneic pig T cell responses and xenogeneic human anti-pig T cell responses. Both anti-CD154 mAb and CTLA4IgG4 cross-reacted on pig cells. While anti-CD154 mAb and CTLA4IgG4 both inhibited the primary allogeneic pig MLRs, CTLA4IgG4 (7.88 microg/ml) was considerably more inhibitory than anti-CD154 mAb (100 microg/ml) at optimal doses. Anti-CD154 mAb inhibited the production of IFN-gamma by 75%, but did not inhibit IL-10 production, while CTLA4IgG4 completely inhibited the production of both IFN-gamma and IL-10. In secondary allogeneic pig MLRs, CTLA4IgG4, but not anti-CD154 mAb, induced Ag-specific T cell anergy. CTLAIgG4 completely blocked the indirect pathway of allorecognition, while anti-CD154 mAb blocked the indirect response by approximately 50%. The generation of porcine CTLs was inhibited by CTLA4IgG4, but not by anti-CD154 mAb. Human anti-porcine xenogeneic MLRs were blocked by CTLA4IgG4, but only minimally by anti-CD154 mAb. Finally, CTLA4IgG4 prevented secondary xenogeneic human anti-porcine T cell responses. These data indicate that blockade of the B7-CD28 pathway was more effective than blockade of the CD40-CD154 pathway in inhibiting allogeneic pig T cell responses and xenogeneic human anti-pig T cell responses in vitro. These findings have implications for inhibiting cell-mediated immune responses in pig-to-human xenotransplantation.
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MESH Headings
- Abatacept
- Amino Acid Sequence
- Animals
- Antibodies, Blocking/analysis
- Antibodies, Blocking/pharmacology
- Antigens, CD
- Antigens, Differentiation/immunology
- Antigens, Heterophile/immunology
- B7-1 Antigen/immunology
- CD28 Antigens/immunology
- CD40 Antigens/immunology
- CD40 Ligand
- CTLA-4 Antigen
- Cells, Cultured
- Clonal Anergy/immunology
- Cytotoxicity, Immunologic/immunology
- Humans
- Immunoconjugates
- Immunoglobulin G/analysis
- Immunoglobulin G/pharmacology
- Immunosuppressive Agents/pharmacology
- Interferon-gamma/antagonists & inhibitors
- Interferon-gamma/biosynthesis
- Interleukin-10/antagonists & inhibitors
- Interleukin-10/biosynthesis
- Isoantigens/immunology
- Lymphocyte Activation/immunology
- Lymphocyte Culture Test, Mixed
- Membrane Glycoproteins/antagonists & inhibitors
- Membrane Glycoproteins/immunology
- Molecular Sequence Data
- Swine
- Swine, Miniature
- T-Lymphocytes, Cytotoxic/immunology
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Zhou L, Song Y, Geng D. [The reconstruction of laryngeal function in subtotal laryngectomy with preservation of arytenoid cartilage]. ZHONGHUA ER BI YAN HOU KE ZA ZHI 1999; 34:309-10. [PMID: 12764833] [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 evaluate subtotal laryngectomy with preservation of arytenoid cartilage to reconstruct laryngeal function in T3 glottic or supraglottic laryngeal cancer. METHODS Subtotal laryngectomy with preservation of arytenoid cartilage to reconstruct laryngeal function was reviewed in 20 patients with T3 laryngeal cancer(3 cases with glottic cancer and 17 cases with supraglottic cancer). Recurrent laryngeal nerve was preserved during surgery. The mucous membranes between cricoid cartilage and pharynx were sewed up accordingly. RESULTS All patients had restored phonation and swallowing functions. The 3- and 5-year survival rates were 94.1% and 91.8% respectively. Decannulation rate was 95.0%. CONCLUSION Subtotal laryngectomy with preservation of arytenoid cartilage is recommended for T3 laryngeal cancer.
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Geng D, Baker DP, Foley SF, Zhou C, Stieglitz K, Roberts MF. A 20-kDa domain is required for phosphatidic acid-induced allosteric activation of phospholipase D from Streptomyces chromofuscus. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1430:234-44. [PMID: 10082951 DOI: 10.1016/s0167-4838(99)00005-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Two phospholipase D (PLD) enzymes with both hydrolase and transferase activities were isolated from Streptomyces chromofuscus. There were substantial differences in the kinetic properties of the two PLD enzymes towards monomeric, micellar, and vesicle substrates. The most striking difference was that the higher molecular weight enzyme (PLD57 approximately 57 kDa) could be activated allosterically with a low mole fraction of phosphatidic acid (PA) incorporated into a PC bilayer (Geng et al., J. Biol. Chem. 273 (1998) 12195-12202). PLD42/20, a tightly associated complex of two peptides, one of 42 kDa and the other 20 kDa, had a 4-6-fold higher Vmax toward PC substrates than PLD57 and was not activated by PA. N-Terminal sequencing of both enzymes indicated that both components of PLD42/20 were cleavage products of PLD57. The larger component included the N-terminal segment of PLD57 and contained the active site. The N-terminus of the smaller peptide corresponded to the C-terminal region of PLD57; this peptide had no PLD activity by itself. Increasing the pH of PLD42/20 to 8.9, followed by chromatography of PLD42/20 on a HiTrap Q column at pH 8.5 separated the 42- and 20-kDa proteins. The 42-kDa complex had about the same specific activity with or without the 20-kDa fragment. The lack of PA activation for the 42-kDa protein and for PLD42/20 indicates that an intact C-terminal region of PLD57 is necessary for activation by PA. Furthermore, the mechanism for transmission of the allosteric signal requires an intact PLD57.
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Geng D, Chura J, Roberts MF. Activation of phospholipase D by phosphatidic acid. Enhanced vesicle binding, phosphatidic acid-Ca2+ interaction, or an allosteric effect? J Biol Chem 1998; 273:12195-202. [PMID: 9575167 DOI: 10.1074/jbc.273.20.12195] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of bacterial phospholipase D (PLD), a Ca2+-dependent enzyme, toward phosphatidylcholine bilayers was enhanced 7-fold by incorporation of 10 mol % phosphatidic acid (PA) in the vesicle bilayer. Addition of other negatively charged lipids such as phosphatidylinositol, phosphatidylmethanol, and oleic acid either inhibited or had no effect on enzyme activity. Only negatively charged lipids with a free phosphate group, phosphatidylinositol 4-phosphate and lyso-PA, had the same effect as PA on enzyme activity. Changes in vesicle curvature and fusion were not the reason for PA activation; rather, a metal ion-induced lateral segregation of PA in the vesicle bilayer correlated with PLD activation. Significant PA activation was also observed with monomer phosphatidylcholine substrate upon the addition of PA vesicles. The PA activation was caused by Ca2+.PA interacting with PLD at an allosteric site other than active site.
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Roberts MF, Wu Y, Zhou C, Geng D, Tan C. Mechanism and structure based inhibitors of phospholipase C enzymes. ADVANCES IN ENZYME REGULATION 1996; 36:57-71. [PMID: 8869740 DOI: 10.1016/0065-2571(95)00017-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PI-specific PLC enzymes are a key component of phosphatidylinositol-mediated signaling pathways since the hydrophobic product, diacylglycerol, activates protein kinase C and the water-soluble product, inositol trisphosphate, is involved in Ca2+ mobilization. Nonspecific, or PC-PLC, enzymes can generate diacylglycerol without Ca2+ mobilization. A series of inhibitors, both lipophilic and water-soluble, have been synthesized to target each of these two classes of PLC enzymes. Design of the inhibitors was based on proposed enzyme mechanisms and available crystal structures. The solution conformations of the lipophilic phospholipid analogs, (diheptanoylphosphatidyl(2-O-methyl)inositol for PI-PLC and a dihexanoyl-sn-(3-N-benzylaminoglycero)phosphoramidocholine for PC-PLC, have been determined using NMR methodology and the interaction of these compounds with bacterial enzymes has been examined. Water-soluble inhibitors include strained cyclic phosphonates for PI-PLC and vanadate for PC-PLC. An eventual goal of this work is to generate compounds that specifically target each type of intracellular PLC activity.
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Miao CY, Li WX, Geng D, Tao LA, Zuberbuhler JS, Zuberbuhler JR. Effect of high altitude on prevalence of congenital heart disease. Chin Med J (Engl) 1988; 101:415-8. [PMID: 3146471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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