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Abstract
A unifying theoretical framework for analyzing stochastic data from single-particle tracking (SPT) in viscoelastic materials is presented. A generalization of the bead-spring model for linear polymers is developed from a molecular point of view and from the standpoint of phenomenological linear viscoelasticity. The hydrodynamic interaction in the former is identified as the dashpots in the latter. In elementary terms, the intimate correspondence between time-correlation of the fluctuation measurements and transient relaxation kinetics after perturbation is discussed, and the central role of the fluctuation-dissipation relation is emphasized. The work presented here provides a bridge between the microscopic and the macroscopic views of linear viscoelastic biological materials, and is applicable to membrane protein diffusion, linear DNA chain dynamics, and mechanics of intracellular cytoskeletal networks.
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152
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Qian H, Tand L. [Prevention and control of malaria in China, in last 50 years]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 2000; 21:225-7. [PMID: 15460009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
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153
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Chen M, Jiang GL, Fu XL, Wang LJ, Qian H, Chen GY, Zhao S, Liu TF. The impact of overall treatment time on outcomes in radiation therapy for non-small cell lung cancer. Lung Cancer 2000; 28:11-9. [PMID: 10704704 DOI: 10.1016/s0169-5002(99)00113-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE A retrospective study was carried out to evaluate the impact of overall treatment time (OTT) on the results of radiation therapy for non-small cell lung cancer (NSCLC). MATERIALS AND METHODS From Jan. 1990 to Dec. 1996, 256 patients with stages I-IIIb NSCLC entered this analysis. All patients received definitive radiotherapy. Biologically effective dose (BED) was used to standardize the irradiation effects. The correlation between OTT and local progression-free survival was analyzed by linear-regression and Cox proportional hazard models. The prognostic variables for survival and distant metastasis were also briefly studied. RESULTS OTT had been shortened in 64 patients because of an accelerated hyperfractioned irradiation, while OTT was prolonged i n 114 patients due to interruptions of irradiation courses. The main ca uses of interruption were machine breakdown or delayed preparations of c errobend block for boost fields (55%), holidays (11%) and treatment toxi city and side effects (34%). Patients tre ated with prolonged OTT (> 45 days) had significant poorer local progression-free survival than whom with OTT of </=45 days, 1, 3 and 5 year actuarial local progression-free survivals being 49, 17 and 15% for the former, and 74, 35 and 25% for the latter, respectively (P<0.001). BED-T that contained the factor of OTT correlated directly to local controls, which implied that BED-T represented radiobiological effects accurately, in other words, OTT had played a role in determining the radiobiological effects. Linear-regression on 103 cases treated with BED of 80-85 Gy(10) showed that 3 year local progression-free survival decreased by 9% per week with prolongation of OTT, or vice versa it increased by 9% per week with shortening OTT in an OTT range of 30-76 days. Cox multivariate analyses confirmed that OTT was an independent prognostic factor for local controls. CONCLUSION OTT may have played an important role in determining local controls in radiotherapy for NSCLC. One should always keep in mind to make the OTT as short as possible, provided the patients can tolerate it, and to reduce irradiation interruptions for whatever reasons to a minimum.
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154
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Qian H. [Microdissection technique used in the research of tumors]. ZHONGHUA BING LI XUE ZA ZHI = CHINESE JOURNAL OF PATHOLOGY 2000; 29:136-9. [PMID: 12790134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
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155
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Qian H, Qian M. Pumped biochemical reactions, nonequilibrium circulation, and stochastic resonance. PHYSICAL REVIEW LETTERS 2000; 84:2271-2274. [PMID: 11017261 DOI: 10.1103/physrevlett.84.2271] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/1999] [Indexed: 05/23/2023]
Abstract
Based on a master equation formalism for mesoscopic, unimolecular biochemical reactions, we show the periodic oscillation arising from severe nonequilibrium pumping is intimately related to the periodic motion in recently studied stochastic resonance (SR). The white noise in SR is naturally identified with the temperature in the biochemical reactions; the drift in the SR is associated with the circular flux in nonequilibrium steady state (NESS). As in SR, an optimal temperature for biochemical oscillation is shown to exist. A unifying framework for Hill's theory of NESS and the SR without periodic forcing is presented. The new formalism provides an analytically solvable model for SR.
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156
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Bian J, Zhang B, Qian H, Chen S. [Effect of protein expression on antisense c-myc and PCNA for vascular smooth muscle cells]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 2000; 38:140-2. [PMID: 11832013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To study the methods of inhibiting proliferation of vascular smooth muscle cells (VSMCs), we observed the change of protein expression after using antisense c-myc, PCNA for VSMCs. METHODS The sense, antisense, and mismatched oligomers for c-myc or PCNA were individually delivered to the cultured VSMCs. Using Western blot, immunohistochemistry assay and image analysis system, we observed the change of c-myc and PCNA protein expression in the VSMCs. RESULTS Antisense c-myc, PCNA at concentration of 10 micromol/L can successfully inhibit the expression of c-myc, PCNA protein in the VSMCs (P < 0.05), but the sense and the mismatched do not have this effect (P > 0.05). CONCLUSION The data suggested that the antisense c-myc, PCNA could attenuate the protein expression of c-myc, PCNA, and it is an effective method for the inhibition of VSMCs hyperplasia.
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Tsui L, McArthur J, Lamphere L, Gyuris J, George S, Qian H. Chimeric P27-p16 Gene Therapy Inhibits Balloon Injury Induced Neointimal Hyperplasia in Cholesterol-Fed Rabbits. J Vasc Interv Radiol 2000. [DOI: 10.1016/s1051-0443(00)70194-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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158
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Thomas WG, Qian H, Chang CS, Karnik S. Agonist-induced phosphorylation of the angiotensin II (AT(1A)) receptor requires generation of a conformation that is distinct from the inositol phosphate-signaling state. J Biol Chem 2000; 275:2893-900. [PMID: 10644757 DOI: 10.1074/jbc.275.4.2893] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors are thought to isomerize between distinct inactive and active conformations, an idea supported by receptor mutations that induce constitutive (agonist-independent) activation. The agonist-promoted active state initiates signaling and, presumably, is then phosphorylated and internalized to terminate the signal. In this study, we examined the phosphorylation and internalization of wild type and constitutively active mutants (N111A and N111G) of the type 1 (AT(1A)) angiotensin II receptor. Cells expressing these receptors were stimulated with angiotensin II (AngII) and [Sar(1),Ile(4),Ile(8)]AngII, an analog that only activates signaling through the constitutive receptors. Wild type AT(1A) receptors displayed a basal level of phosphorylation, which was stimulated by AngII. Unexpectedly, the constitutively active AT(1A) receptors did not exhibit an increase in basal phosphorylation nor was phosphorylation enhanced by AngII stimulation. Phosphorylation of the constitutively active receptors was unaffected by pretreatment with the non-peptide AT(1) receptor inverse agonist, EXP3174, and was not stimulated by the selective ligand, [Sar(1),Ile(4),Ile(8)]AngII. Paradoxically, [Sar(1),Ile(4), Ile(8)]AngII produced a robust ( approximately 85% of AngII), dose-dependent phosphorylation of the wild type AT(1A) receptor at sites in the carboxyl terminus similar to those phosphorylated by AngII. Moreover, internalization of both wild type and constitutive receptors was induced by AngII, but not [Sar(1),Ile(4),Ile(8)]AngII, providing a differentiation between the phosphorylated and internalized states. These data suggest that the AT(1A) receptor can attain a conformation for phosphorylation without going through the conformation required for inositol phosphate signaling and provide evidence for a transition of the receptor through multiple states, each associated with separate stages of receptor activation and regulation. Separate transition states may be a common paradigm for G protein-coupled receptors.
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Abstract
A three-state stochastic model of motor protein [Qian, Biophys. Chem. 67 (1997) pp. 263-267] is further developed to illustrate the relationship between the external load on an individual motor protein in aqueous solution with various ATP concentrations and its steady-state velocity. A wide variety of dynamic motor behavior are obtained from this simple model. For the particular case of free-load translocation being the most unfavorable step within the hydrolysis cycle, the load-velocity curve is quasi-linear, V/Vmax = (cF/Fmax-c)/(1-c), in contrast to the hyperbolic relationship proposed by A.V. Hill for macroscopic muscle. Significant deviation from the linearity is expected when the velocity is less than 10% of its maximal (free-load) value--a situation under which the processivity of motor diminishes and experimental observations are less certain. We then investigate the dependence of load-velocity curve on ATP (ADP) concentration. It is shown that the free load Vmax exhibits a Michaelis-Menten like behavior, and the isometric Fmax increases linearly with ln([ATP]/[ADP]). However, the quasi-linear region is independent of the ATP concentration, yielding an apparently ATP-independent maximal force below the true isometric force. Finally, the heat production as a function of ATP concentration and external load are calculated. In simple terms and solved with elementary algebra, the present model provides an integrated picture of biochemical kinetics and mechanical energetics of motor proteins.
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Barmack N, Guo H, Kim H, Qian H, Qian ZY. Neuronally modulated transcription of a glycine transporter in rat dorsal cochlear nucleus and nucleus of the medial trapezoid body. J Comp Neurol 1999. [DOI: 10.1002/(sici)1096-9861(19991213)415:2<175::aid-cne3>3.0.co;2-u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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161
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Barmack NH, Guo H, Kim HJ, Qian H, Qian Z. Neuronally modulated transcription of a glycine transporter in rat dorsal cochlear nucleus and nucleus of the medial trapezoid body. J Comp Neurol 1999; 415:175-88. [PMID: 10545158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Neurotransmitter transporters limit transmitter concentration at the postsynaptic membrane by removing neurotransmitters from the synaptic cleft. Not only do neurotransmitter transporters contribute to the regulation of synaptic transmission, but they themselves might be dynamically regulated by neuronal activity of the neurons in which they are expressed. In this experiment, we investigated the question of whether the transcription of two different glycine transporters, Glyt1 and Glyt2, is influenced by neuronal activity. These transporters are found in the dorsal cochlear nucleus (DCN) and medial nucleus of the trapezoid body. Glyt1 and Glyt2 mRNA were measured by using hybridization histochemistry and a semiquantitative reverse transcription polymerase chain reaction. Decreases in auditory primary afferent activity, caused by either unilateral labyrinthectomy or disruption of the middle ear ossicles, caused a reduction in Glyt2, but not Glyt1 mRNA in the ipsilateral DCN and in the contralateral medial nucleus of the trapezoid body. Acoustic stimulation at either 10 kHz or 40 kHz was used to provide controlled increases in primary afferent activity, evoking localized increases in Glyt2 mRNA in clusters of neurons in the DCN. The location of these clusters corresponded to the regions of the auditory tonotopic map devoted to these frequencies. The duration of changes in Glyt2 mRNA evoked by unilateral labyrinthectomy, measured with the reverse transcription polymerase chain reaction, was 5-10 days. These data provide the first example of in vivo regulation of transporter transcription by neuronal activity.
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162
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Qian H, Ripps H. Response kinetics and pharmacological properties of heteromeric receptors formed by coassembly of GABA rho- and gamma 2-subunits. Proc Biol Sci 1999; 266:2419-25. [PMID: 10643085 PMCID: PMC1690471 DOI: 10.1098/rspb.1999.0941] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Two of the gamma-aminobutyric acid (GABA) receptors, GABAA and GABAC, are ligand-gated chloride channels expressed by neurons in the retina and throughout the central nervous system. The different subunit composition of these two classes of GABA receptor result in very different physiological and pharmacological properties. Although little is known at the molecular level as to the subunit composition of any native GABA receptor, it is thought that GABAC receptors are homomeric assemblies of rho-subunits. However, we found that the kinetic and pharmacological properties of homomeric receptors formed by each of the rho-subunits cloned from perch retina did not resemble those of the GABAC receptors on perch bipolar cells. Because both GABAA and GABAC receptors are present on retinal bipolar cells, we attempted to determine whether subunits of these two receptor classes are capable of interacting with each other. We report here that, when coexpressed in Xenopus oocytes, heteromeric (rho 1B gamma 2) receptors formed by coassembly of the rho 1B-subunit with the gamma 2-subunit of the GABAA receptor displayed response properties very similar to those obtained with current recordings from bipolar cells. In addition to being unresponsive to bicuculline and diazepam, the time-constant of deactivation, and the sensitivities to GABA, picrotoxin and zinc closely approximated the values obtained from the native GABAC receptors on bipolar cells. These results provide the first direct evidence of interaction between GABA rho and GABAA receptor subunits. It seems highly likely that coassembly of GABAA and rho-subunits contributes to the molecular organization of GABAC receptors in the retina and perhaps throughout the nervous system.
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163
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Abstract
We present a graphical method for a unifying, quantitative analysis of molecular bonding-force measurements by atomic force microscopy (AFM). The method is applied to interpreting a range of phenomena commonly observed in the experimental AFM measurements of noncovalent, weak bonds between biological macromolecules. The analysis suggests an energy landscape underlying the intermolecular force and demonstrates that many observations, such as "snaps-on," "jumps-off," and hysteresis loops, are different manifestations of a double-well energy landscape. The analysis gives concrete definitions for the operationally defined "attractive" and "adhesive" forces in terms of molecular parameters. It is shown that these operationally defined quantities are usually functions of the experimental setup, such as the stiffness of the force probe and the rate of its movement. The analysis reveals a mechanical instability due to the multistate nature of molecular interactions and provides new insight into macromolecular viscosity. The graphical method can equally be applied to a quantitative analysis of multiple unfolding of subunits of the giant muscle protein titin under AFM.
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164
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Yonghao T, Qian H, Chuanyuan L, Yandell DW. Deletions and point mutations of p16,p15 gene in primary tumors and tumor cell lines. CHINESE MEDICAL SCIENCES JOURNAL = CHUNG-KUO I HSUEH K'O HSUEH TSA CHIH 1999; 14:200-5. [PMID: 12894891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Aberrations of chromosome 9 p21-22 are involved in the genesis of many forms of cancer. The gene p16 and p15 have been assigned to this region. Both p16 and p15 are an inhibitor of cyclin D-cdk4,cyclin D-cdk6 complex and have been implicated in a wide variety of cancer types, including the germline of patients with familial melanoma. In order to investigate and compare the status of p16,p15 gene in primary tumors and cell lines, we examined 357 primary tumors and 29 cell lines derived from diverse tumor types. In addition to analysis of these primary tumors and cell lines, blood specimens from 91 patients either with sporadic multiple cancers or from cancer-prone families were also analyzed. The data showed the following: 1) Homozygous deletions of p16,p15 were comparatively rare and far less common than previously reported, although hemizygous deletions were observed in a significant fraction of many tumor types; 2) the incidence of p16,p15 deletions (either homozygous deletions or heterozygous deletions) varied significantly among different tumor types; 3) most deletions involved in both p16 and p15 genes; 4) sequence variations in the coding sequence of p16,p15 were comparatively rare among these tumor types, though mutations and polymorphisms were identified; 5) some tumors which showed LOH at 9p, containing p16 and p15 gene, did not show deletions or point mutations in the p16,p15 gene. 6) In a subset of retinoblastoma and osteosarcoma where no Rb gene mutations were present a significant fraction was found to contain p16,p15 gene deletions.
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165
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Qian H, Pipolo L, Thomas WG. Identification of protein kinase C phosphorylation sites in the angiotensin II (AT1A) receptor. Biochem J 1999; 343 Pt 3:637-44. [PMID: 10527943 PMCID: PMC1220596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Protein kinase C (PKC) phosphorylates the C-terminus of the type 1 angiotensin II receptor (AT(1)), although the exact site(s) of phosphorylation are unidentified. In the present study, we examined the phosphorylation of epitope-tagged wild-type AT(1A) receptors, transiently expressed in Chinese hamster ovary K1 cells, in response to angiotensin II (AngII) and following selective activation and inhibition of PKC. This phosphorylation was compared with mutant receptors where C-terminal serine residues (Ser(331), Ser(338) and Ser(348)) within three putative PKC consensus sites were replaced with alanine, either individually or in combination. Stimulation by AngII or the phorbol ester PMA to activate PKC induced an increase in phosphorylation of the wild-type AT(1A) receptor, which was prevented by truncation of the receptor C-terminus to remove the last 34 amino acids, including Ser(331), Ser(338) and Ser(348). Whereas single alanine mutation (Ser(331)Ala, Ser(338)Ala and Ser(348)Ala) resulted in decreased receptor phosphorylation, no single mutant completely inhibited either AngII- or PMA-induced phosphorylation. Combined mutation of the three PKC consensus sites caused an approximately 70% reduction in PMA-mediated phosphorylation. The approximately 60% reduction in AngII (1 microM)-induced phosphorylation of this triple mutant and the partial inhibition of wild-type receptor phosphorylation by bisindolylmaleimide, a specific PKC inhibitor, suggest a significant contribution of PKC to agonist-stimulated regulation. The ratio of PKC to total receptor phosphorylation was greatest at low doses of AngII (1 nM), consistent with the idea that PKC phosphorylates and regulates receptor function at low levels of stimulation, whereas phosphorylation by other kinases is more prevalent at high levels of agonist stimulation. To determine if a single PKC site is favoured when the contribution of PKC varies, the phosphorylation of wild-type and mutant receptors was examined over a range of AngII concentrations (0, 1, 10 and 100 nM). At all AngII concentrations, single mutation of Ser(331), Ser(338) or Ser(348) was incapable of completely preventing receptor phosphorylation, suggesting no clear preference for PKC consensus-site utilization. Together, these results indicate a redundancy in PKC phosphorylation of the AT(1A) receptor, whereby all three consensus sites are utilized to some degree following homologous (AngII) and heterologous (PMA) stimulation. The contribution of PKC phosphorylation to receptor regulation is unclear, but multiple PKC phosphorylation of the AT(1A) receptor may allow independent and/or complementary events to occur at the three separate sites of the C-terminus.
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Yang F, Qian H, Feng J. [In vitro study of 6B11GM to induce cellular immunity in patients with ovarian carcinoma]. ZHONGHUA FU CHAN KE ZA ZHI 1999; 34:660-3. [PMID: 11479947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
OBJECTIVE In order to explore the possibility of ovarian carcinoma anti-idiotypic single chain antibody (6B11scFV) and human granueocyte-macrophage colony stimulating factor (hGM-CSF) fusion protein 6B11GM as tumor vaccine. METHODS Mononuclear cells, T cells and monocyte used as antigen presenting cell (APC) were separated from peripheral blood, and tumor cells were obtained from ascitic fluid in the same patients. In vitro T cell proliferation and autologous tumor cell cytotoxicity assay were applied. RESULTS 6B11GM could induce T cell proliferation in vitro which was antigen specific. Cytotoxicity of mononuclear cells to autologous tumor cells increased after primed with 6B11GM. CONCLUSION 6B11GM could induce efficient cellular immunity in patients with ovarian carcinoma, hopefully may be used for ovarian carcinoma vaccine.
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167
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Ni G, Qian H, Chen Y. [The analysis of auditory brainstem response during resection of brainstem neoplasm]. ZHONGHUA ER BI YAN HOU KE ZA ZHI 1999; 34:232-5. [PMID: 12764780] [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 changes of auditory brainstem response (ABR) and its role in monitoring auditory functions during the brainstem surgery. METHODS The data of 400 ABRs from 5 operations for removal of astrocytic glioma, cavernomas or dermoid from the brainstem were analyzed. The changes in latencies, amplitudes and wavefroms were dynamically observed and statistically analyzed with t test and Factor analysis. RESULTS Surgical manipulations, such as stretching, separation and extrusion, induced the prolongation of ABR peaks and interpeak latencies of waves I, III, V. The amplitudes of waves decreased. Three out of 5 cases presented reversible changes in latencies and wave forms. The dynamical analysis showed: The maximal variable range of latency(LMVD) was more than 11.30%, the maximal reversible degree of latency(LMRD) was more than 53.85%, the time of convalescent half-value latency(LCHT) was around 8-40 min, AMVD was more than 40%, the AMRD was more than 200%, and the ACHT was around 5-40 min. In 2 out of the 5 patients the postoperative ABR latencies kept prolonged, some postoperative waves were malformed and difficult to be identified, One case died, another lost consciousness, their LMRDs were less than 33.33%. These findings suggested that surgical intervention had significant effects on the ABR latency (P < 0.01). CONCLUSION ABR offers a promise for sensitive detection of the brainstem function. Its latency, amplitude and waveform show us dynamic changes of the brainstem status and can be used as an index during the operation on the brainstem and its adjacent region.
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Tomomori C, Tanaka T, Dutta R, Park H, Saha SK, Zhu Y, Ishima R, Liu D, Tong KI, Kurokawa H, Qian H, Inouye M, Ikura M. Solution structure of the homodimeric core domain of Escherichia coli histidine kinase EnvZ. NATURE STRUCTURAL BIOLOGY 1999; 6:729-34. [PMID: 10426948 DOI: 10.1038/11495] [Citation(s) in RCA: 208] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Escherichia coli osmosensor EnvZ is a protein histidine kinase that plays a central role in osmoregulation, a cellular adaptation process involving the His-Asp phosphorelay signal transduction system. Dimerization of the transmembrane protein is essential for its autophosphorylation and phosphorelay signal transduction functions. Here we present the NMR-derived structure of the homodimeric core domain (residues 223-289) of EnvZ that includes His 243, the site of autophosphorylation and phosphate transfer reactions. The structure comprises a four-helix bundle formed by two identical helix-turn-helix subunits, revealing the molecular assembly of two active sites within the dimeric kinase.
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169
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Thomas WG, Pipolo L, Qian H. Identification of a Ca2+/calmodulin-binding domain within the carboxyl-terminus of the angiotensin II (AT1A) receptor. FEBS Lett 1999; 455:367-71. [PMID: 10437806 DOI: 10.1016/s0014-5793(99)00904-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To identify regulators of the type 1A angiotensin II receptor (AT1A), we investigated the interaction of cellular proteins with a fusion protein containing the rat AT1A receptor carboxyl-terminus. An approximately 20 kDa cytoplasmic protein interacted with the fusion protein in a Ca2+-dependent manner and was identified as calmodulin. A control peptide with high affinity for Ca2+/calmodulin and a peptide corresponding to a membrane proximal portion of the AT1A receptor carboxyl-terminus with analogy to known calmodulin-binding sequences were synthesised and tested for calmodulin-binding. Using in vitro binding assays combined with gel shift analysis, we demonstrated the formation of complexes between calmodulin and both peptides, which were Ca2+-dependent and of 1:1 stoichiometry. Affinity gels produced from these peptides also purified calmodulin from cell extracts. These results suggest a novel feedback regulation of the AT1A receptor by Ca2+/calmodulin and identify the membrane proximal region of the carboxyl-terminus as a focal point for interactions important for AT1A receptor function.
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170
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Qian H, Raymond GM, Bassingthwaighte JB. Stochastic fractal behavior in concentration fluctuation and fluorescence correlation spectroscopy. Biophys Chem 1999; 80:1-5. [PMID: 10457592 PMCID: PMC2872158 DOI: 10.1016/s0301-4622(99)00031-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Fluctuations in the concentration of Brownian particles in one and two dimensions, or any reasonable measurement of the concentration such as in fluorescence correlation spectroscopy, is shown to be a stochastic fractal with a long tail. Being singular at omega = 0, the power spectrum of the fluctuation S(omega) approximately omega-1/2 for diffusion in one dimension, approximately log omega in two dimensions, but non-singular in three dimensions. This discovery provides one simple physical mechanism for possible long-memory fractal behavior, and its implications to various biological processes are discussed.
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171
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Qian H, Dowling JE, Ripps H. A single amino acid in the second transmembrane domain of GABA rho subunits is a determinant of the response kinetics of GABAC receptors. JOURNAL OF NEUROBIOLOGY 1999; 40:67-76. [PMID: 10398072 DOI: 10.1002/(sici)1097-4695(199907)40:1<67::aid-neu6>3.0.co;2-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The rho subunits that constitute the gamma-aminobutyric acid (GABA)C receptors of retinal neurons form a unique subclass of ligand-gated chloride channels that give rise to sustained GABA-evoked currents that exhibit slow offset (deactivation) kinetics. We exploited this property to examine the molecular mechanisms that govern the disparate response kinetics and pharmacology of perch GABA rho1B and rho2A subunits expressed in Xenopus oocytes. Using a combination of domain swapping and site-directed mutagenesis, we identified the residues at amino acid position 320 in the second transmembrane domain as an important determinant of the receptor kinetics of GABAC receptors. When the site contains a proline residue, as in wild-type rho1 subunits, the receptor deactivates slowly; when serine occupies the site, as in wild-type rho2 subunits, the time course of deactivation is more rapid. In addition, we found that the same site also altered the pharmacology of GABA rho receptors, e.g., when the serine residue of the rho2A receptor was changed to proline, the response of the mutant receptor to imidazole-4-acetic acid (I4AA) mimicked that of the rho1B receptor. However, despite gross changes in receptor pharmacology, the apparent binding affinity for the drug was not significantly altered. These findings provide further evidence that the second transmembrane domain is involved in the gating mechanism that governs the response properties of the various rho receptor subunits. It is noteworthy that the proline residue in native rho1 subunits and the serine residue of rho2 subunits are well conserved in all species, a good indication that the presence of multiple GABA rho subunits serves to generate GABAC receptors that display the wide range of response kinetics observed on various types of retinal neurons.
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172
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Yang F, Qian H, Huang H. [The construction and expression of 6B11scFv anti-idiotypic antibody and human granulocyte-macrophage-colony stimulating factor in Escherichia coli]. ZHONGHUA FU CHAN KE ZA ZHI 1999; 34:417-9. [PMID: 11360654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
OBJECTIVE To enhance the antigenicity of an anti-idiotypic single chain antibody 6B11 mimicking ovarian cancer antigen. METHODS Using DNA recombinant technique, a recombinant fusion protein expression vector was constructed. This vector linked 6B11scFv cDNA and human GM-CSF with a linker. Protein productions were induced with the temperature change in E. Coli and analyzed with western blot. RESULTS The expressed fusion protein can be reacted with both anti-human antibody and COC166-9(AB1 of 6B11). CONCLUSION The recombinant fusion protein keeps the activities of both components and may be used as tumor vaccine for ovarian cancer.
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173
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Zhao Y, Qian H, Li W. [Cerebral metastases in patients with epithelial ovarian carcinoma]. ZHONGHUA FU CHAN KE ZA ZHI 1999; 34:420-2. [PMID: 11360655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
OBJECTIVE To detect the rate of occurrence, the relevant factors, the diagnosis and treatment of cerebral metastases in patients with epithelial ovarian carcinoma. METHODS The clinical data were analyzed in 4 cases of cerebral metastases from 132 cases of epithelial ovarian carcinoma after treatment between 1989-1997. RESULTS The rate of cerebral metastases was 3%. The related factors were advanced stage, and tumor cells differentiation, but no related with the histologic type. More cases of cerebral metastasis were found because of the prolonged survival after cytoreductive surgery and systemic chemotherapy as well as the extraabdominal metastasis. CONCLUSIONS Computed tomography and magnetic resonance imaging were the important diagnostic methods. Combined treatments including surgery, radiotherapy and chemotherapy can improve the patients status and prolong their lives.
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Qian H, Neplioueva V, Shetty GA, Channon KM, George SE. Nitric oxide synthase gene therapy rapidly reduces adhesion molecule expression and inflammatory cell infiltration in carotid arteries of cholesterol-fed rabbits. Circulation 1999; 99:2979-82. [PMID: 10368113 DOI: 10.1161/01.cir.99.23.2979] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hypercholesterolemia reduces nitric oxide bioavailability, manifested by reduced endothelium-dependent vascular relaxation, and also induces vascular adhesion molecule expression and inflammatory cell infiltration. We have previously shown that gene therapy with NO synthase in hypercholesterolemic rabbits substantially reverses the deficit in vascular relaxation. In the present study, we show that NO synthase gene therapy rapidly and substantially reduces vascular adhesion molecule expression, lipid deposition, and inflammatory cell infiltration. METHODS AND RESULTS Thirty male New Zealand White rabbits were maintained on a 1% cholesterol diet for 11 to 13 weeks, then underwent carotid artery gene transfer with Ad.nNOS or Ad.betaGal (recombinant adenoviruses expressing neuronal NO synthase or beta-galactosidase, respectively), or received medium alone in a sham procedure. Arteries were harvested at 1 and 3 days after gene transfer, and the following parameters were determined by immunohistochemical and image-analysis techniques: intercellular adhesion molecule-1, vascular cell adhesion molecule-1, lipid deposition by oil red O staining, lymphocyte infiltration (CD43-positive cells), and monocyte infiltration (RAM-11-positive cells). In Ad.nNOS-treated arteries, all markers were significantly decreased relative to Ad. betaGal or sham-treated arteries within 3 days after gene transfer. Ad.nNOS had a particularly striking impact on monocyte infiltration; as early as 24 hours after gene transfer, Ad.nNOS-treated arteries had >3-fold fewer monocytes than Ad.betaGal- or sham-treated arteries. CONCLUSIONS NO synthase gene therapy rapidly ameliorates several markers of atherosclerosis in the cholesterol-fed rabbit.
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