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Lin BS, Chang CC, Wang CT. Renormalization group analysis for thermal turbulent transport. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:016304. [PMID: 11304350 DOI: 10.1103/physreve.63.016304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2000] [Indexed: 05/23/2023]
Abstract
In this study, we continue with our previous renormalization group analysis of incompressible turbulence, aiming at determination of various thermal transport properties. In particular, the temperature field T is considered a passive scalar. The quasinormal approximation is assumed for the statistical correlation between the velocity and temperature fields. A differential argument leads to derivation of the turbulent Prandtl number Pr(t) as a function of the turbulent Peclet Pe(t) number, which in turn depends on the turbulent eddy viscosity nu(t). The functional relationship between Pr(t) and Pe(t) is comparable to that of Yakhot et al. [Int. J. Heat Mass Transf. 30, 15 (1987)] and is in close consistency with direct-numerical-simulation results as well as measured data from experiments. The study proceeds further with limiting the operation of renormalization group analysis, yielding an inhomogeneous ordinary differential equation for an invariant thermal eddy diffusivity sigma. Simplicity of the equation renders itself a closed-form solution of sigma as a function of the wave number k, which, when combined with a modified Batchelor's energy spectrum for the passive temperature T, facilitates determination of the Batchelor constant C(B) and a parallel Smagorinsky model and the model constant C(P) for thermal turbulent energy transport.
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Wang CT, Chen SS, Chiang CC. Assembly and release of human immunodeficiency virus type 1 Gag proteins containing tandem repeats of the matrix protein coding sequences in the matrix domain. Virology 2000; 278:289-98. [PMID: 11112503 DOI: 10.1006/viro.2000.0655] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have constructed human immunodeficiency virus (HIV) gag mutants by increasing the matrix protein (MA) sequences via tandemly repeated duplication of the central 107-MA codons. Instead of a total of 132 amino acid residues for the wild-type MA, the resultant mutants designated as MA2, MA3, and MA4 contained a total of 242, 352, and 462 codons in the MA domains, respectively. Analysis indicated that the addition of 110 or 220 amino acid residues to the MA did not significantly affect the assembly, release, and processing of particles; however, particle production was markedly reduced when another copy of 110 residues was added to the MA. Subcellular fractionation analysis suggested that the MA tandem repeat mutations enhanced the Gag membrane affinity, in a manner which correlated with the copy number of MA sequences. The effects of enhanced membrane affinity were substantially reduced when sequences downstream of the capsid (CA) domain were deleted. Sucrose density gradient fractionation analysis showed that particles produced by the large insertion mutants possessed wild-type (wt) HIV particle density. Truncation of sequences downstream of the nucleocapsid (NC) domains of the mutants did not influence the budding of particles. In contrast, particle budding was severely impaired when sequences downstream of the CA domain were truncated. Particle densities for the large Gag proteins, which were truncated at the C-terminus of CA, were about 1.12-1.14 g/ml lower than that for wt. Our results suggest that the HIV MA domain could adopt insertions of large protein sequences, and strongly support the proposal that the NC and p2 domains play a crucial role in the process of correct Gag protein packing.
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Zhang R, Li L, Yu LN, Bai RJ, Zhang FQ, Wang CT, Xu XY. [3D solid model of mandible with dental arch via LOM method]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 2000; 9:240-2. [PMID: 15014772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE Based on 3D reconstruction data from CT scanning, a solid model of mandible with dental arch is obtained via a rapid prototype machine using LOM method. METHODS 3D reconstruction data is transferred to STL file using software of Delcam(UK),which will be fed to Magics RP software for detection and rebuilding. Reproduction of the papery model of mandible with dental arch is then performed with highly geometric similarity. RESULTS The RP model of mandible with dental arch is obtained. CONCLUSION Accuracy of the reproduction model meets the demands of students in prosthetic dentistry,which gives the possibility of computer aided design of prosthetic dentistry based on 3D solid model.
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Li L, Zhang R, Yu LN, Zhang FQ, Wang CT, Xu XY. [3D geometric simulation of mandible with dental arch from CT data]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 2000; 9:235-6. [PMID: 15014771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE A 3D geometric simulation of mandible with dental arch from CT has been obtained in this study. METHODS This process uses automatic system assisted with interactive action to get 2D contour data from CT images,then 3D wireframe model and solid model were obtained by using CAD/CAM software Pro-E(USA) and DELCAM(UK). RESULTS 3D solid model of mandible with dental arch were presented which can be fully edited. CONCLUSION This model can be applied to further educational and clinical researches such as RP,biomechanics simulation in prosthetic dentistry.The processes of simulation has wide applications in clinical practice of dentistry and dental education.
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Wang CT, Sun JS, Hou SM. Mycobacterial infection of the upper extremities. J Formos Med Assoc 2000; 99:710-5. [PMID: 11000735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
BACKGROUND AND PURPOSE Mycobacterial infection of the upper extremities is extremely rare. To make an early accurate diagnosis is often difficult, and the treatment is, therefore, frequently delayed in clinical practice. This paper describes the diagnosis and treatment of mycoabacterial infection of the upper extremities in a series of patients treated at National Taiwan University Hospital. METHODS The medical records of 15 patients with mycobacterial infection of the upper extremities treated between 1985 and 1998 were retrospectively analyzed. The diagnosis of mycobacterial infection was established by positive culture results, the presence of acid-fast bacilli, or characteristic histopathologic findings. RESULTS Mycobacterial infection was suspected on initial examination in only two patients. The duration between the onset of symptoms and correct diagnosis averaged 37.5 months (range, 3 wk to 209 mo). The involved sites of mycobacterial infection included the wrist in nine patients, the elbow in two, the hand in two, the humerus in two, the forearm in one, and the shoulder in one. Three patients suffered from multifocal musculoskeletal mycobacterial infection. Microbiologic studies identified Mycobacterium tuberculosis in four patients and nontuberculous mycobacteria (NTM) in four. Characteristic histopathologic findings of mycobacterial infection including caseation, granulomatous inflammation, eosinophilic epithelioid cells, Langhan's giant cells, and lymphocytic aggregates were noted in all 15 patients. All patients received chemotherapy and 14 patients underwent surgical treatment. The mean duration of follow-up was 46 months (range, 15-97 months). Treatment failed in two of the patients with multifocal NTM infection and in one patient whose mycobacterial infection was identified by histopathology. CONCLUSIONS Mycobacterial infection should be included in the differential diagnosis of infection of the upper extremities. Treatment failures are more frequent in patients with multifocal NTM infection.
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Wang CT, Yang AH, Chiang CC. Analysis of a human immunodeficiency virus type 1 gag mutant with an engineered 110-amino-acid insertion in the matrix protein domain. J Med Virol 2000; 61:423-32. [PMID: 10897059 DOI: 10.1002/1096-9071(200008)61:4<423::aid-jmv3>3.0.co;2-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A human immunodeficiency virus (HIV) matrix (MA) protein mutant was constructed by duplication of 107 codons of the HIV-1 MA domain. This MA protein duplication mutant (MAII) still could assemble and process particles, had a wild-type (wt) HIV particle density, and possessed reverse transcriptase activity of about 80% of the wild type virus level. The incorporation of HIV Env and viral RNA genome was not greatly affected. The MAII was noninfectious or poorly infectious, however, when pseudotyped with an amphotropic murine leukemia virus envelope protein or with the HIV envelope protein. Although the MAII mutant displayed an immunofluorescence staining pattern similar to that of the wild type virus, subcellular fractionation studies indicated that the membrane association of MAII Gag precursors was unstable under high-salt conditions. Electron microscopic studies showed that the mutant had a decreased density of particle cores compared with that of the wild type virus, suggesting an altered arrangement of the packed proteins. As this insertion in the MA gene caused no major effects on virus assembly implies that the HIV-1 gag has the potential to adapt large insertions of extra coding sequences without loss of the ability to direct particle assembly and release.
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Wang CT, Chin SY, Navar LG. Impairment of pressure-natriuresis and renal autoregulation in ANG II-infused hypertensive rats. Am J Physiol Renal Physiol 2000; 279:F319-25. [PMID: 10919852 DOI: 10.1152/ajprenal.2000.279.2.f319] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic infusions of initially subpressor doses of angiotensin II (ANG II) lead to progressive hypertension over a 2-wk period and to augmented intrarenal ANG II levels. The present study was performed to investigate total renal blood flow (RBF) and medullary blood flow (MBF) autoregulatory behavior and pressure-natriuresis in ANG II-infused hypertensive rats and how these are modified by concomitant treatment with an ANG II AT(1) receptor antagonist. ANG II-infused rats (n = 27) were prepared by administration of ANG II at 60 ng/min via osmotic minipump for 13 days. Twelve of the ANG II-infused hypertensive rats were treated with losartan in the drinking water (30 mg. kg.(-1) day(-1)). Rats were anesthetized with pentobarbital sodium (50 mg/kg, ip) and prepared for renal function measurements. An aortic clamp was placed above the junction of the left renal artery to reduce renal arterial pressure. Autoregulatory responses for renal plasma flow, overall RBF, and glomerular filtration rate were impaired in ANG II-infused hypertensive rats; however, MBF autoregulation was not disrupted. Most strikingly, pressure-natriuresis was markedly suppressed in ANG II-infused hypertensive rats. Chronic treatment with losartan prevented the impairment of the pressure-natriuresis relationship caused by chronic ANG II infusion. These findings demonstrate that chronic ANG II infusion leads to marked impairment of sodium excretion and suppression of the pressure-natriuresis relationship, which may contribute to the progressive hypertension that occurs in this model. These renal effects are prevented by simultaneous treatment with an AT(1) receptor blocker.
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Lee SF, Wang CT, Liang JY, Hong SL, Huang CC, Chen SS. Multimerization potential of the cytoplasmic domain of the human immunodeficiency virus type 1 transmembrane glycoprotein gp41. J Biol Chem 2000; 275:15809-19. [PMID: 10747937 DOI: 10.1074/jbc.m000601200] [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: 11/06/2022] Open
Abstract
We previously demonstrated that an envelope mutant of human immunodeficiency virus type 1 lacking the entire cytoplasmic domain interferes in trans with the production of infectious virus by inclusion of the mutant envelope into the wild-type envelope complex. We also showed that the envelope incorporation into virions is not affected when the wild-type envelope is coexpressed with the mutant envelope. These results suggest that an oligomeric structure of the cytoplasmic domain is functionally required for viral infectivity. To understand whether the cytoplasmic domain of human immunodeficiency virus type 1 transmembrane protein gp41 has the potential to self-assemble as an oligomer, in the present study we fused the coding sequence of the entire cytoplasmic domain at 3' to the Escherichia coli malE gene, which encodes a monomeric maltose-binding protein. The expressed fusion protein was examined by chemical cross-linking, sucrose gradient centrifugation, and gel filtration. The results showed that the cytoplasmic domain of gp41 assembles into a high-ordered structural complex. The intersubunit interaction of the cytoplasmic domain was also confirmed by a mammalian two-hybrid system that detects protein-protein interactions in eucaryotic cells. A cytoplasmic domain fragment expressed in eucaryotic cells was pulled down by glutathione-Sepharose 4B beads via its association with another cytoplasmic domain fragment fused to the C terminus of the glutathione S-transferase moiety. We also found that sequences encompassing the lentiviral lytic peptide-1 and lentiviral lytic peptide-2, which are located within residues 828-856 and 770-795, respectively, play a critical role in cytoplasmic domain self-assembly. Taken together, the results from the present study indicate that the cytoplasmic domain of gp41 by itself is sufficient to assemble into a multimeric structure. This finding supports the hypothesis that a multimeric form of the gp41 cytoplasmic domain plays a crucial role in virus infectivity.
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Wang CT, Chou YC, Chiang CC. Assembly and processing of human immunodeficiency virus Gag mutants containing a partial replacement of the matrix domain by the viral protease domain. J Virol 2000; 74:3418-22. [PMID: 10708461 PMCID: PMC111845 DOI: 10.1128/jvi.74.7.3418-3422.2000] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We constructed human immunodeficiency virus (HIV) mutants by replacing the matrix domain with sequences encoding the viral protease or p6* and protease. The chimeras retaining matrix myristylation and processing signals underwent efficient autoprocessing with severely defective particle budding. The budding defects of the chimeras were rescued by suppressing the chimera protease activity either through addition of an HIV protease inhibitor or through inactivating the chimera protease via a substitution mutation of the catalytic aspartic acid residue. This resulted in the release of chimeric virus-like particles with the density of a wild-type retrovirus particle. In addition, the assembly-competent but processing-defective chimeras produced proteolytically processed particles with significant reverse transcriptase activity when a downstream native pol gene was present. These results suggest that HIV has the potential to adapt heterologous sequences in place of the matrix sequence without major effects on virus-like particle budding. In addition, the positions of the protease and substrate accessibility may contribute significantly toward avoiding a premature Gag or Gag-Pol process, which leads to severe defects in both particle budding and incorporation.
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Hu YH, Poivey JP, Rouvier R, Wang CT, Tai C. Heritabilities and genetic correlations of body weights and feather length in growing Muscovy selected in Taiwan. Br Poult Sci 1999; 40:605-12. [PMID: 10670671 DOI: 10.1080/00071669986972] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
1. Heritabilities and genetic correlations in the base population of a closed strain of Muscovy duck, moderately selected for body weight at 10 weeks of age, have been estimated from the data of 9 successive generations for the following traits: male and female body weight at 10 and 18 weeks of age (BW10m, BW18m, BW10f, BW18f) and length of the 8th primary feather at 10 weeks of age (F110m, F110f). 2. Multivariate REML with an animal model was used, pooling data from the 9 generations (3283 and 3289 male and female offspring respectively). The same trait expressed in male and female was considered as 2 different traits. 3. The 8th primary feather was longer in females than in males by 6% to 22% at 10 weeks of age. Body weight was heavier in males than in females by 42% to 58% at 10 weeks of age and by 57% to 75% at 18 weeks of age. 3. The heritability estimates for body weight traits showed moderate values, being a little higher for females than for males at the same age, increasing with age from h2=0.24 at BW10m to h2=0.43 at BW18f. 4. The heritability estimates for feather length showed that a greater response would be obtained in selection for male feather length (h2=0.37) than for female length (h2=0.14). Both have high genetic correlations with body weight so they could be indirectly improved. 5. Heritabilities of the difference in body weights between males and females at 10 weeks (h2=0.07) and 18 weeks of age (h2=0.10) were small, as well as for feather length (h2=0.10). It would probably be difficult to modify sexual dimorphism in body weight through selection. 6. Genetic correlations between BW10m, BW18m and BW10f, BW18f were respectively r(g)=0.77 and r(g)=0.80. They were larger for body weight at the same ages between males and females, r(g)=0.90 (r(g)=0.88 between F110m and F110f). Body weight in males and females at the same age should be better considered as 2 different traits in a selection programme. 7. The cumulated predicted genetic gains expressed per unity of the genetic standard deviation (sigma(g)) over the 8 generations of selection were 1.3 sigma(g) and 1.4 sigma(g) respectively for the BW10m and BW10f. The predicted correlated responses were 1.2 sigma(g) for body weights at 18 weeks of age, 0.9 sigma(g) and 0.7 sigma(g) for F110f and F110m respectively.
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Wang CT, Lai HY, Yang CC. Sequence requirements for incorporation of human immunodeficiency virus gag-beta-galactosidase fusion proteins into virus-like particles. J Med Virol 1999; 59:180-8. [PMID: 10459153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
The incorporation of human immunodeficiency virus type 1 (HIV-1) Gag-beta-galactosidase (Gag-beta-gal; GBG) fusion proteins into HIV virus-like particles in the presence of HIV Gag proteins was studied. HIV Gag-beta-gal fusion constructs were cotransfected individually into COS7 cells with or without an HIV Gag protein expression plasmid. Release of HIV GBG fusion proteins from the cells were measured by assay of the medium versus intracellular beta-gal activities. Analysis indicates that fusion proteins (constructs HIVGBG, GBG 1919 and 1877) retaining the C-terminal portion of the CA and the adjacent NC domains were efficiently assembled into virus-like particles. Fusion proteins with deleted sequences covering the N-terminal portions of the gag sequences (GBG 831, 1147, 1419, 1447, 1511, 1552, 1600, 1630, 1684, 1715, and 1752) were impaired in entry into virus-like particles. The presence of CA major homology region (MHR) in the fusion proteins had no significant effects on inducing fusion protein incorporation when the C-terminal CA sequences in the fusion proteins were truncated (GBG 1841 and 1801). Subcellular fractionation studies indicated that most fusion proteins including the nonmyristylated one were enriched in the crude membrane fraction. Exceptions to this rule were fusion proteins with intact MHR but truncated C-terminal CA sequences, which possessed low levels of membrane association. However, assembly of fusion proteins into HIV Gag particles did not correlate with their subcellular fractionation or immunofluorescence localization patterns. Overall, the studies suggest that the very C-terminal CA and adjacent NC sequences are the primary determinants for incorporation of HIV Gag-beta-gal fusion proteins into virus particles.
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Wang CT. Diagnosing and treating asymptomatic tuberculosis infection. CANADIAN FAMILY PHYSICIAN MEDECIN DE FAMILLE CANADIEN 1999; 45:2397-404. [PMID: 10540699 PMCID: PMC2328627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
OBJECTIVE To summarize relevant parts of the guidelines recommended by the Canadian and American Thoracic Societies for diagnosis and management of asymptomatic tuberculosis (TB) infection. QUALITY OF EVIDENCE The latest guidelines published by the Canadian and American Thoracic Societies were reviewed. Unfortunately, neither of these guidelines state explicitly how recommendations were derived. The references accompanying each set of guidelines, however, suggest that they were developed by extensive literature review of the subject and consensus among expert panels. MAIN MESSAGE Only higher-risk patients should receive a TB screening test (Mantoux test) to minimize the possibility of false-positive test results. The cutoff points for positive tests vary to reflect the pretest likelihood of TB infection. An induration 5 mm or greater is considered positive in patients at highest risk of TB infection, that is, HIV-infected patients, close contacts of active TB cases, and patients with chest x-ray abnormalities suggestive of previous untreated TB. All other patients are considered positive if they have induration greater than 10 mm according to the Canadian guideline. A 15-mm cutoff point, however, is used for patients without risk factors in the American guideline. All patients with positive Mantoux test results should be considered infected with TB. Infected patients should be offered 6 to 12 months of isoniazid prophylaxis if they have HIV infection, if they have medical conditions that increase the risk of TB activation, or if they are younger than 35 years. CONCLUSIONS Prophylactic treatment of infected individuals effectively prevents the spread of TB infection. Family physicians, who most often see patients in the asymptomatic stage of TB infection, are uniquely situated to prevent secondary cases of TB by offering appropriate patients prophylactic treatment. Patients should be counseled about the risk and benefit of prophylactic treatment so they give informed consent for it.
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Su CY, Shiao MS, Wang CT. Differential effects of ganodermic acid S on the thromboxane A2-signaling pathways in human platelets. Biochem Pharmacol 1999; 58:587-95. [PMID: 10413295 DOI: 10.1016/s0006-2952(99)00136-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Ganodermic acid S (GAS) [lanosta-7,9(11),24-triene-3beta,15alpha-diacetoxy-26-oic acid], isolated from the Chinese medicinal fungus Ganoderma lucidum (Fr.) Karst (Polyporaceae), exerted a concentration-dependent inhibition on the response of human gel-filtered platelets (GFP) to U46619 (9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F2alpha), a thromboxane (TX) A2 mimetic. GAS at 2 microM inhibited 50% of cell aggregation. GAS at 7.5 microM inhibited 80% of Ca2+ mobilization, 40% of phosphorylation of myosin light chain and pleckstrin, 80% of alpha-granule secretion, and over 95% of aggregation. GAS also strongly inhibited U46619-induced diacylglycerol formation, arachidonic acid release, and TXB2 formation. An immunoblotting study of protein-tyrosine phosphorylation showed that GAS inhibited the formation of phosphotyrosine proteins at the steps involving the engagement of integrin alphaIIbbeta3 and aggregation. However, GAS did not inhibit U46619-induced platelet shape change or the inhibitory effect of U46619 on the prostaglandin E1-evoked cyclic AMP level in GFP. It is concluded that GAS inhibits platelet response to TXA2 on the receptor-Gq-phospholipase Cbeta1 pathway, but not on the receptor-G1 pathway.
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Wang CT, Zhang HG, Rocheleau TA, ffrench-Constant RH, Jackson MB. Cation permeability and cation-anion interactions in a mutant GABA-gated chloride channel from Drosophila. Biophys J 1999; 77:691-700. [PMID: 10423418 PMCID: PMC1300364 DOI: 10.1016/s0006-3495(99)76924-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
To investigate the structural basis of anion selectivity of Drosophila GABA-gated Cl(-) channels, the permeation properties of wild-type and mutant channels were studied in Xenopus oocytes. This work focused on asparagine 319, which by homology is one amino acid away from a putative extracellular ring of charge that regulates cation permeation in nicotinic receptors. Mutation of this residue to aspartate reduced channel conductance, and mutation to lysine or arginine increased channel conductance. These results are consistent with an electrostatic interaction between this site and permeating anions. The lysine mutant, but not the arginine mutant, formed a channel that is permeable to cations, and this cannot be explained in terms of electrostatics. The lysine mutant had a 25-mV reversal potential in solutions with symmetrical Cl(-) and asymmetrical cations. The permeability ratio of K(+) to Cl(-) was determined as 0. 33 from reversal potential measurements in KCl gradients. Experiments with large organic cations and anions showed that cation permeation can only be seen in the presence of Cl(-), but Cl(-) permeation can be seen in the absence of permeant cations. Measurements of permeability ratios of organic anions indicated that the lysine mutant has an increased pore size. The cation permeability of the lysine-containing mutant channel cannot be accounted for by a simple electrostatic interaction with permeating ions. It is likely that lysine substitution causes a structural change that extends beyond this one residue to influence the positions of other channel-forming residues. Thus protein conformation plays an important role in enabling ion channels to distinguish between anions and cations.
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Zheng YL, Chen L, Zhang FQ, Wang CT. [Effect of the abutments with reduced periodontal support on stress distribution of support tissue]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1999; 8:104-6. [PMID: 15048284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE:This study applied finite element analysis (FEA) compared stress distribution characteristics of mandible,bilateral,SJ-1 bolt(extracoronal) distal extension attachment prostheses when the abutments were subject to eight different loss of periodontal support.METHODS:Finite element analysis.RESULTS:It was shown that periodontal support loss results in increased stress of the terminal abutment tooth without sudden changes.CONCLUSION:Compared favorable stress distribution result from splinted compromised abutment,and the first premolar periodontal support loss less than that of the second premolar and this loss below 30%.
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Zheng YL, Chen L, Zhang FQ, Wang CT. [Effect of the number of splinted abutments on stress distribution of support tissue]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1999; 8:101-3. [PMID: 15048283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
OBJECTIVE:This study applied an SJ-1 bolt attachment partial denture to restorate distal extension edentulous areas.Finite element analysis (FEA) was used to monitor induced around abutment supporting tissues under the different number of splinted abutments.METHODS:Finite element analysis. RESULTS:The result demonstrate that the reduction of the number of splinted unit from three to two resulted in an insignificant increase of stress records,whereas reduction of the number from two to one resulted in a significant increase of stress nine times greater than the three unit splint values.CONCLUSION:Hence,at least two teeth on each side should be splinted when SJ 1 bolt(extracoronal) distal extension attachment prostheses are used.
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Navar LG, Harrison-Bernard LM, Imig JD, Wang CT, Cervenka L, Mitchell KD. Intrarenal angiotensin II generation and renal effects of AT1 receptor blockade. J Am Soc Nephrol 1999; 10 Suppl 12:S266-72. [PMID: 10201881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
The intrarenal renin-angiotensin system plays a critical role in the paracrine regulation of renal function and the pathophysiology of hypertension. Angiotensin II (AngII) is formed intrarenally from systemically delivered angiotensin I (AngI) and intrarenally formed AngI. Intrarenal AngII content, which is greater than can be explained by the circulating AngII concentrations, is compartmentalized such that proximal tubule concentrations of AngI and AngII greatly exceed plasma concentrations. Proximal tubule cells are thought to secrete AngII or precursors of AngII into the tubular fluid to activate luminal AngII receptors. Recent immunohistochemical studies have demonstrated an abundance of AT1 receptors on the luminal surface of proximal and distal tubule cells and on afferent and efferent arteriolar vascular smooth muscle cells and mesangial cells of glomeruli. Activation of luminal AT1 receptors stimulates tubular sodium reabsorption rate. To evaluate the direct effects of AT1 receptor blockade on renal function in AngII-dependent hypertension, experiments were performed on two-kidney, one-clip (2K1C) Goldblatt hypertensive rats. Although the nonclipped kidney is renin-depleted, the intrarenal AngII levels are not suppressed, and AngII concentrations in proximal tubular fluid remain high (10(-8) M). Candesartan was administered into the renal artery of nonclipped kidneys to avoid the confounding consequences of decreases in arterial pressure. Blockade of intrarenal AT1 receptors elicited significant increases in GFR, renal blood flow, sodium excretion, and fractional sodium excretion, suggesting synergistic actions on tubular transport and vascular smooth muscle cells.
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Wang CT, Huang SC. The Ilizarov technique for treatment of sequelae of childhood-acquired bone and joint infection. J Formos Med Assoc 1999; 98:175-82. [PMID: 10365536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Abstract
Bone and joint infections in childhood can result in various sequelae including deformity and limb length discrepancy (LLD). Management of these sequelae is difficult and must be individualized. In this study, we retrospectively examined the efficacy of treatment with Ilizarov techniques in 30 patients suffering from sequelae of bone and joint infections in childhood, treated from 1989 to 1994. These cases comprised 17 hip infections, two septic shoulders, and 11 cases of osteomyelitis (4 femurs, 5 tibiae, 1 humerus, and 1 forearm). All patients had some evidence of LLD. There were 13 cases of hip deformity and 10 cases of unstable hips. There were also 10 cases of angular deformity and five of nonunion of bone. The mean age at treatment was 21 years. Twenty-eight patients underwent Ilizarov lengthening procedures and 18 of them underwent deformity or instability correction simultaneously. Two patients underwent Ilizarov deformity correction only. Various techniques were used, including Schanz osteotomy plus mid-shaft femoral lengthening and distraction callotasis with and without an intramedullary nail. Postoperative complications included stiffness of joints in six patients, pin tract infection in six, fracture in five, malunion in five, nonunion in four, callus shortening in four, nerve palsy in two, and over-lengthening in one. The mean duration of follow-up was 72 months. The average length gain was 6.6 cm in shortened bones, with a mean external fixator index of 40.5 days/cm. All patients were satisfied with the functional and cosmetic results. We conclude that Ilizarov techniques are effective in treating sequelae of childhood infections of bones and joints.
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Su CY, Shiao MS, Wang CT. Predominant inhibition of ganodermic acid S on the thromboxane A2-dependent pathway in human platelets response to collagen. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1437:223-34. [PMID: 10064905 DOI: 10.1016/s1388-1981(98)00012-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Ganodermic acid S (GAS), a membrane acting agent, exerts multiple effects on human platelet function (C.N. Wang et al. (1991) Biochem. J. 277, 189-197). The study reported how GAS affected the response of human gel-filtered platelets (GFP) to collagen. The agent inhibited cell aggregation by prolonging lag and shape change periods and decreasing the initial cell aggregation rate. However, the inhibitory efficiency was less than its inhibition on GFP response to U46619, a thromboxane (TX) A2 mimetic. In the agent-effect on biochemical events, GAS effectively inhibited Ca2+ mobilization, phosphorylation of myosin light chain, dense granule secretion and TXB2 generation. The inhibitions might originate from blocking Ca2+ mobilization of the TXA2-dependent pathway. GAS partially decreased the phosphorylation of most phosphotyrosine proteins from early activation to the integrin alphaIIbbeta3-regulated steps. The agent did not affect the phosphorylation of three proteins at the steps regulated by integrin alphaIIbbeta3. The results suggest that GAS inhibits the collagen response predominantly on the TXA2-dependent signaling, and the tyrosine kinase-dependent pathway in collagen response plays a major role in aggregation.
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Wang CT. Practice Tips. Two-step Mantoux test. CANADIAN FAMILY PHYSICIAN MEDECIN DE FAMILLE CANADIEN 1999; 45:55-7. [PMID: 10928799 PMCID: PMC2328064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Cervenka L, Wang CT, Mitchell KD, Navar LG. Proximal tubular angiotensin II levels and renal functional responses to AT1 receptor blockade in nonclipped kidneys of Goldblatt hypertensive rats. Hypertension 1999; 33:102-7. [PMID: 9931089 DOI: 10.1161/01.hyp.33.1.102] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
-Previous studies have shown that whereas the nonclipped kidney in two-kidney, one clip (2K1C) rats undergoes marked depletion of renin content and renin mRNA, intrarenal angiotensin II (Ang II) levels are not suppressed; however, the distribution and functional consequences of intrarenal Ang II remain unclear. The present study was performed to assess the plasma, kidney, and proximal tubular fluid levels of Ang II and the renal responses to intrarenal Ang II blockade in the nonclipped kidneys of rats clipped for 3 weeks. The Ang II concentrations in proximal tubular fluid averaged 9.19+/-1.06 pmol/mL, whereas plasma Ang II levels averaged 483+/-55 fmol/mL and kidney Ang II content averaged 650+/-66 fmol/g. Thus, as found in kidneys from normal rats with normal renin levels, proximal tubular fluid concentrations of Ang II are in the nanomolar range. To avoid the confounding effects of decreases in mean arterial pressure (MAP), we administered the nonsurmountable AT1 receptor antagonist candesartan directly into the renal artery of nonclipped kidneys (n=10). The dose of candesartan (0.5 microg) did not significantly decrease MAP in 2K1C rats (152+/-3 versus 148+/-3 mm Hg), but effectively prevented the renal vasoconstriction elicited by an intra-arterial bolus of Ang II (2 ng). Candesartan elicited significant increases in glomerular filtration rate (GFR) (0.65+/-0. 06 to 0.83+/-0.11 mL. min-1. g-1) and renal blood flow (6.3+/-0.7 to 7.3+/-0.9 mL. min-1. g-1), and proportionately greater increases in absolute sodium excretion (0.23+/-0.07 to 1.13+/-0.34 micromol. min-1. g-1) and fractional sodium excretion (0.38+/-0.1% to 1.22+/-0. 35%) in 2K1C hypertensive rats. These results show that proximal tubular fluid concentrations of Ang II are in the nanomolar range and are much higher than can be explained on the basis of plasma levels. Further, the data show that the intratubular levels of Ang II in the nonclipped kidneys of 2K1C rats remain at levels found in kidneys with normal renin content and could be exerting effects to suppress renal hemodynamic and glomerular function and to enhance tubular reabsorption rate.
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Wang CT, Li JJ, Lai HY, Hu BS. A human cell line constitutively expressing HIV-1 Gag and Gag-Pol gene products. J Med Virol 1999; 57:17-24. [PMID: 9890417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A human cell line constitutively expressing the HIV-1 gag and pol genes products was established. The cell line was established by stably transfecting 293 cells with a plasmid construct that expresses the HIV Gag and Pol and can confer the transfectants resistant to mycophenolic acid. Particles generated from transient expression of the plasmid construct were noninfectious when pseudotyped with HIV envelope or with amphotropic murine leukemia virus envelope proteins. However, virus-like Gag particles produced by the stable cell line were appropriately processed, exhibited a wild-type retrovirus particle density, and possessed significant reverse-transcriptase (RT) activities. Continuous passage of the cell line either in the presence or absence of mycophenolic acid had no major effects on the Gag processing efficiency, particle assembly, or RT activity release. It was also demonstrated that the proteolytic processing of the virus-like particles released from the cell line was inhibited by an HIV protease inhibitor, saquinavir. The establishment of a stable cell line producing noninfectious but proteolytically processed HIV Gag particles offers a safe, convenient tool for biochemical and immunological analysis of virus-like particle assembly and is very useful for the development of anti-HIV protease drugs.
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Navar LG, Harrison-Bernard LM, Wang CT, Cervenka L, Mitchell KD. Concentrations and actions of intraluminal angiotensin II. J Am Soc Nephrol 1999; 10 Suppl 11:S189-95. [PMID: 9892162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Although the presence of angiotensin II (AngII) receptors on the luminal membranes of proximal tubule cells has been recognized for many years, recent immunohistochemical studies using polyclonal and monoclonal antibodies to the AngII type 1 (AT1) receptor have demonstrated an abundance of the AT1 receptor not only on the luminal surface of proximal tubule cells but also on the luminal surfaces of distal nephron segments. An important role for these receptors in the regulation of tubular transport mechanisms was indicated by the recent findings of remarkably high proximal intratubular concentrations of AngII (in the range of 10(-9) to 10(-8) M). The high intratubular concentrations of AngII, as well as angiotensin I and angiotensinogen, are much greater than can be explained on the basis of delivery via glomerular filtration. When coupled with the findings demonstrating the presence of angiotensinogen and angiotensinogen mRNA in proximal tubule cells, the data indicate that AngII or precursors of AngII are secreted directly into the proximal tubule lumen by the epithelial cells. Although the mechanisms responsible for the regulation of intratubular AngII concentrations remain to be determined, micropuncture studies have provided direct evidence that activation of intraluminal AT1 receptors by AngII exerts a substantial stimulatory influence on sodium and bicarbonate transport by both proximal and distal tubules. Collectively, these data provide support for the hypothesis that activation of luminal AT1 receptors by AngII present in the tubular fluid contributes importantly to regulation of the tubular reabsorption rate.
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MESH Headings
- Angiotensin II/analysis
- Angiotensin II/physiology
- Angiotensinogen/analysis
- Animals
- Biological Transport
- Biopsy, Needle
- Body Fluids/metabolism
- Cell Membrane/metabolism
- Cells, Cultured
- Epithelial Cells/metabolism
- Kidney Tubules, Distal/metabolism
- Kidney Tubules, Proximal/metabolism
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/analysis
- Receptors, Angiotensin/physiology
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Wang CT, Lai HY, Li JJ. Analysis of minimal human immunodeficiency virus type 1 gag coding sequences capable of virus-like particle assembly and release. J Virol 1998; 72:7950-9. [PMID: 9733833 PMCID: PMC110128 DOI: 10.1128/jvi.72.10.7950-7959.1998] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We have constructed a series of human immunodeficiency virus (HIV) gag mutants by progressive truncation of the gag coding sequence from the C terminus and have combined these mutants with an assembly-competent matrix domain deletion mutation (DeltaMA). By using several methods, the particle-producing capabilities of each mutant were examined. Our analysis indicated that truncated Gag precursors lacking most of C-terminal gag gene products assembled and were released from 293T cells. Additionally, a mutant with a combined deletion of the MA (DeltaMA) and p6 domains even produced particles at levels comparable to that of the wild-type (wt) virus. However, most mutants derived from combination of the DeltaMA and the C-terminal truncation mutations did not release particles as well as the wt. Our smallest HIV gag gene product capable of virus-like particle formation was a 28-kDa protein which consists of a few MA amino acids and the CA-p2 domain. Sucrose density gradient fractionation analysis indicated that most mutants exhibited a wt retrovirus particle density. Exceptions to this rule were mutants with an intact MA domain but deleted downstream of the p2 domains. These C-terminal truncation mutants possessed particle densities of 1.13 to 1.15 g/ml, lower than that of the wt. The N-terminal portions of the CA domain, which have been shown to be dispensable for core assembly, became critical when most of the MA domain was deleted, suggesting a requirement for an intact CA domain to assemble and release particles.
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Cervenka L, Wang CT, Navar LG. Effects of acute AT1 receptor blockade by candesartan on arterial pressure and renal function in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F940-5. [PMID: 9612332 DOI: 10.1152/ajprenal.1998.274.5.f940] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Experiments were performed on normal anesthetized rats to determine the effects of candesartan, a novel AT1 receptor antagonist, on the arterial pressure and renal hemodynamic responses to bolus doses of angiotensin II (ANG II) and on renal hemodynamics and sodium excretion. Control arterial pressure responses to bolus ANG II doses of 10, 50, 100 and 1,000 ng were 26 +/- 6, 54 +/- 7, 57 +/- 7, and 79 +/- 7 mmHg; the decreases in cortical renal blood flow (CRBF), measured with laser-Doppler flowmetry, were 47 +/- 9, 64 +/- 8, 71 +/- 6, and 82 +/- 6%. The vasoconstrictor responses to ANG II up to 1,000 ng were completely blocked by candesartan doses of 1 and 0.1 mg/kg, whereas treatment with 0.01 mg/kg candesartan attenuated the arterial pressure and CRBF responses. The higher doses of candesartan (1 and 0.1 mg/kg) elicited rapid decreases in arterial pressure, leading to associated decreases in sodium excretion. Renal blood flow (RBF), glomerular filtration rate (GFR), and urine flow also decreased following treatment with candesartan at 1 mg/kg. In contrast, when candesartan was given at 0.01 mg/kg, which did not decrease arterial pressure significantly, there were significant increases in GFR (16 +/- 4), RBF (9 +/- 2), urine flow (11 +/- 2), sodium excretion (35 +/- 7), and fractional sodium excretion (39 +/- 8%). The inability to overcome blockade, even with very high ANG II doses, indicates that candesartan is a potent noncompetitive blocker of ANG II pressor and renal vasoconstrictor effects. The lower candesartan dose that did not cause significant hypotension elicited substantial increases in RBF, GFR, and sodium excretion, revealing the direct renal vasodilator and natriuretic effects of AT1 receptor blockade.
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