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Shu X, Zhou J, Cai C, Zeng X, Zeng Q, Yi X. [Schistosoma japonicum: purification and diagnostic application of recombinant 32 kD antigen]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 2001; 23:331-4. [PMID: 11189385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Separation and purification of rSj32 were carried out with SDS-PAGE and electroelution technique. The purified rSj32, AWA and SEA were used to examine sera of patients with schistosomiasis, healthy individuals and patients with other parasitic diseases by ELISA. The results showed that the molecule weight of rSj32 was 37 kD. The sensitivity and specificity of rSj32 as a coating antigen in ELISA were as good as those of AWA and SEA. It is suggested that rSj32 antigen is a potential antigen for immunodiagnosis of schistosomiasis japonica.
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152
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Bao G, Kang H, Dong Y, Zhu R, Chao Y, Yi X, Chen M. [Effects of stress level on the biomechanical behavior of the temporomandibular joint disc in domestic pigs]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 2000; 17:418-20. [PMID: 11211829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
This study aimed to examine the responses of the temporomandibular joint (TMJ) disc against compression, to clarify the property of viscoelasticity and permeability of the disc, and to provide experimental data for further analyzing the mechanism of stress dissipation within the TMJ disc. With the use of confined compression mechanics and biphasic theory, creep experiments on eight TMJ discs of four domestic pigs were performed under three stress levels(0.07 MPa, 0.13 MPa and 0.30 MPa). The results showed that at 0.07 stress level, the compressive stiffness at 2 seconds of the anterior band(AB), intermediate zone(IZ) and posterior band(PB) of the disc was 4.48 MPa, 3.93 MPa and 6.31 MPa, respectively; the coefficient K of permeability was 0.272 x 10(-12) m4/NS, 0.30 x 10(-12) m4/NS, and 0.042 x 10(-12) m4/NS. At 0.30 Mpa level, the compressive stiffness increased to 14.07 MPa, 13.68 Mpa and 14.00 MPa; the coefficient K lowered to 0.017 x 10(-12) m4/NS, 0.012 x 10(-12) m4/NS and 0.005 x 10(-12) m4/NS. In conclusion, the TMJ disc has viscoelastic and biobiphasic properties against compression. The stiffness of the disc increases with the increment of stress level but the coefficient of permeability decreases. These findings demonstrate that the modulation of stress and of permeability may be two important factors influencing stress dissipation and shock absorption behavior of the disc during compressive and impact loads.
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153
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Yi X, Wang Y, Yu FS. Corneal epithelial tight junctions and their response to lipopolysaccharide challenge. Invest Ophthalmol Vis Sci 2000; 41:4093-100. [PMID: 11095601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
PURPOSE To investigate the expression and cellular distribution of putative tight junction (TJ) proteins occludin, ZO-1, ZO-2, and claudin-1 in rat corneal epithelium and alterations of TJs in cultured human corneal epithelial cells in response to lipopolysaccharide (LPS) challenge. METHODS Immunohistochemistry was used to determine tissue distribution of occludin, ZO-1, ZO-2, and claudin-1 in the rat cornea. Reverse transcription-polymerase chain reaction was used to reveal the expression of mRNAs for claudins in simian virus (SV)40-immortalized human corneal epithelial (THCE) cells. To assess epithelial response to LPS challenge, THCE cells were cultured on the upper chamber of Transwell filters (Costar, Cambridge, MA), transepithelial electrical resistance (TER) was measured using a voltohmmeter. Immunocytochemistry and immunoblotting were used to assess alteration in the levels and localization of TJ-associated proteins occludin, ZO-1, and ZO-2 in LPS-treated THCE cells. RESULTS Occludin, ZO-1, and ZO-2 were found at the cell borders of the superficial layer, whereas claudin-1 was localized mainly in the basal and wing cell layers of rat corneal epithelium. In addition to claudin-1, the transcripts for several other isotypes of claudins-2, -3, -7, -9, -14, and -15 were identified in THCE cells. Treatment of cultured THCE cells with LPS caused a dose- and time-dependent increase in monolayer permeability as assessed by TER measurements. The maximal decrease of TER was observed at approximately 6 to 9 hours after LPS challenge. The TER was then recovered gradually and returned to baseline after 24 hours. Examination of specific proteins associated with TJs by immunoblot analysis and immunomicroscopy revealed changes in the expression levels and localization of some of these proteins after their exposure to LPS. Specifically, LPS challenge resulted in a decrease in the levels of ZO-1 and ZO-2 compared with untreated cells. Reduction of the ZO-2 level was associated with the disappearance of ZO-2 staining from cell borders in 6-hour LPS-treated cells. CONCLUSIONS Occludin, ZO-1, and ZO-2, but not claudin-1, are components of corneal epithelial TJs. LPS induces breakdown of the epithelial barrier through disruption of TJs, and ZO-1 and ZO-2 are targets for the induction.
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154
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Yi X, Vivien B, Lynch C. Clevidipine blockade of L-type Ca2+ currents: steady-state and kinetic electrophysiological studies in guinea pig ventricular myocytes. J Cardiovasc Pharmacol 2000; 36:592-600. [PMID: 11065219 DOI: 10.1097/00005344-200011000-00008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Steady-state and transient effects of clevidipine, a rapidly degraded dihydropyridine (DHP) L-type Ca2+ channel antagonist, were examined on I(Ca) in guinea pig ventricular myocytes. When myocytes were voltage-clamped with holding potential (V(H)) at -80 mV, 10 nM clevidipine decreased I(Ca) at 0 mV by approximately 30%, but >50% when V(H) was -40 mV. Rapid (<50 ms) perfusion switching and repeated depolarizations delivered at 0.5-2 Hz were used to determine the time constants of onset (tau(on)) and recovery from (tau(off)) clevidipine inhibition of I(Ca). The tau(on) and tau(off) were monoexponential functions of time. The tau(on) of I(Ca) inhibition decreased from 21.5 +/- 1.2 to 9.9 +/- 0.9 s when the rapidly applied [clevidipine] was increased from 10 to 100 nM at V(H) = -80 mV; tau(off) was independent of the applied [clevidipine] and was 23.9 +/- 1.1 s. The dissociation constant (K(D)) calculated for clevidipine at V(H) = -80 mV was 65 +/- 3 nM, similar to the IC50 of 78 nM determined in steady-state measurements. Decreasing V(H) to -40 mV increased tau(off) more than threefold to 81 +/- 6 s, and K(D) was markedly decreased to 9.0 +/- 0.8 nM (IC50, 7.1 nM at V(H) = -40 mV). The increased affinity at depolarized V(H) may contribute to the varying concentration-effect relation observed in vivo.
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155
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Kang H, Yi X. [Biomechanics of temporomandibular joint]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 2000; 17:324-7, 345. [PMID: 11285848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Temporomandibular joint (TMJ) is one of the most intricate and complicate loading joints in the human body. Articular cartilage is characteristic of low infiltrative, porous viscoelastic material. In physiological condition, there is a stress-absorbing architecture system in the TMJ cartilage, which consists of collagen-proteoglycan-water gel network. TMJ disc is a specific connective tissue as stress concentration absorber between condyle and articular fossa, but it does not belong to fibrocartilage. Retrodiscal tissue has high compliance of which the role is to play volume-compensating mechanism in joint movement. Lateral wall is a complexed structure out of ligament and capsule with weak tensile strength and tensile rigidity. Therefore, prolonged oral parafunction will result in joint fatigue and failure.
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156
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Yi X, White DM, Aisner DL, Baur JA, Wright WE, Shay JW. An alternate splicing variant of the human telomerase catalytic subunit inhibits telomerase activity. Neoplasia 2000; 2:433-40. [PMID: 11191110 PMCID: PMC1507981 DOI: 10.1038/sj.neo.7900113] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Telomerase, a cellular reverse transcriptase, adds telomeric repeats to chromosome ends. In normal human somatic cells, telomerase is repressed and telomeres progressively shorten, leading to proliferative senescence. Introduction of the telomerase (hTERT) cDNA is sufficient to produce telomerase activity and immortalize normal human cells, suggesting that the repression of telomerase activity is transcriptional. The telomerase transcript has been shown to have at least six alternate splicing sites (four insertion sites and two deletion sites), and variants containing both or either of the deletion sites are present during development and in a panel of cancer cell lines we surveyed. One deletion (beta site) and all four insertions cause premature translation terminations, whereas the other deletion (alpha site) is 36 bp and lies within reverse transcriptase (RT) motif A, suggesting that this deletion variant may be a candidate as a dominant-negative inhibitor of telomerase. We have cloned three alternately spliced hTERT variants that contain the alpha, beta or both alpha and beta deletion sites. These alternate splicing variants along with empty vector and wild-type hTERT were introduced into normal human fibroblasts and several telomerase-positive immortal and tumor cell lines. Expression of the alpha site deletion variant (hTERT alpha-) construct was confirmed by Western blotting. We found that none of the three alternate splicing variants reconstitutes telomerase activity in fibroblasts. However, hTERT alpha- inhibits telomerase activities in telomerase-positive cells, causes telomere shortening and eventually cell death. This alternately spliced dominant-negative variant may be important in understanding telomerase regulation during development, differentiation and in cancer progression.
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MESH Headings
- Alternative Splicing
- Blotting, Western
- Carcinoma/enzymology
- Carcinoma/pathology
- Carcinoma, Non-Small-Cell Lung/enzymology
- Carcinoma, Non-Small-Cell Lung/pathology
- Catalytic Domain
- Cell Line/enzymology
- Cell Line, Transformed/enzymology
- Cell Transformation, Neoplastic/genetics
- Chromosome Aberrations
- Chromosomes, Human/ultrastructure
- DNA, Complementary/genetics
- DNA-Binding Proteins
- Fetal Proteins/chemistry
- Fetal Proteins/genetics
- Fibroblasts/cytology
- Fibroblasts/enzymology
- Genes, Dominant
- Genetic Vectors/genetics
- Humans
- Lung/cytology
- Lung Neoplasms/enzymology
- Lung Neoplasms/pathology
- Male
- Neoplasm Proteins/chemistry
- Neoplasm Proteins/genetics
- Peptide Chain Termination, Translational/genetics
- Prostatic Neoplasms/enzymology
- Prostatic Neoplasms/pathology
- Protein Subunits
- RNA
- Recombinant Fusion Proteins/physiology
- Retroviridae/genetics
- Sequence Deletion
- Skin/cytology
- Telomerase/antagonists & inhibitors
- Telomerase/chemistry
- Telomerase/genetics
- Telomerase/physiology
- Telomere/metabolism
- Telomere/ultrastructure
- Transfection
- Tumor Cells, Cultured/enzymology
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Li Y, Auliff A, Jones MK, Yi X, McManus DP. Immunogenicity and immunolocalization of the 22.6 kDa antigen of Schistosoma japonicum. Parasite Immunol 2000; 22:415-24. [PMID: 10972848 DOI: 10.1046/j.1365-3024.2000.00319.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The 22.6 kDa tegumental-associated antigens of Schistosoma mansoni (Sm22.6) and Schistosoma japonicum (Sj22.6) are of recognized interest in schistosomiasis vaccine development, although no direct vaccination/challenge experiments using either Sm22.6 or Sj22.6 had been previously described. We report that Escherichia coli-expressed reSj22.6 failed to protect mice or water buffaloes against subsequent challenge with S. japonicum cercariae. This was despite the fact that specific IgG (buffaloes) and IgG and IgE (CBA mice) antibodies were generated against the 22.6 kDa molecule, observations consistent with some of our earlier findings. We could find no evidence from immunolocalization studies that Sj22.6 is expressed or exposed on the surface of the adult parasite since it appears to be restricted to the apical cytoplasm of the tegument and is not associated with the apical or basal membrane or any membrane-bound structures in the apical cytoplasm. Nevertheless, Sj22.6 must be released to the immune system during the course of infection because specific anti-Sj22.6 IgG antibodies were present in the sera of nonvaccinated but challenged mice. We conclude that it may be necessary to produce reSj22.6 in a more relevant expression system, such as baculovirus, to further establish its vaccine potential and that detailed immunochemical and immunolocalization studies of early developmental stages may be necessary to determine how Sj22.6 is released or shed in S. japonicum infections.
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158
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Kang H, Yi X, Chen M, Bao G. [A biomechanical study on the retrodiscal tissue of human temporomandibular joint]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 2000; 17:143-5. [PMID: 12557766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
In order to investigate the biomechanical properties and functional mechanism of the retrodiscal tissue (RT) of human temporomandibular joint (TMJ), we conducted a uniaxial tensile test on thirteen RT specimens taken from eight fresh TMJs of the human cadavers aged between 8-15 years (m = 11.8 yrs). The experimental data were analyzed in conjunction with the Quasi-Linear Viscoelastic Theory as proposed by Fung YC to characterize the time-dependent behaviour and the constitutive relationship of the RT. The results showed that the physiological biphasic zone of stress-strain curve lied within 20%-30% strain levels. The elastic modulus (MPa), tensile strength(MPa) and strain to failure(%) were high. There were significant differences in strain to yielding and energy resorption (N.mm) between lateral and medial RT. There was a good agreement between theoretical prediction value and experimental result within 6% strain level. These data suggest that there would be a higher passive deformation and lower safety storage of strength in the RT which could be related to anterior displacement of the TMJ disc and that Fung's Theory can adequately describe the stress-time behaviour and the constitutive relationship of the RT within lower strain rate.
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159
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Xiaodong H, Yi X, Chaoji Z, Zhenhuan Z, Jianxi Z. Overview for the diagnosis and treatment of gallbladder carcinoma. CHINESE MEDICAL SCIENCES JOURNAL = CHUNG-KUO I HSUEH K'O HSUEH TSA CHIH 2000; 15:115-8. [PMID: 12901637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
OBJECTIVE To improve the recognition of diagnosis and treatment of gallbladder cancer. METHODS Retrospective analysis of 52 cases of gallbladder carcinoma in our hospital from 1988 to 1998. RESULTS Preoperative diagnostic rate was 90.3%, of which 12 cases (23%) were early stage of carcinoma. The total operation resection rate was 55.8%, for which only 17.8% were advance stage of carcinoma. CONCLUSION The early diagnosis is the key factor of increasing treatment successful rate. The following are the symptoms that raise our special attention to carcinoma of galbladder: (1) Age over 50 have recurrent cholecystitis and with past history of gallstone; (2) Congenital malformation of bile duct; (3) Local thickening and irregularity of gallbladder wall; (4) Polypoid lesion larger than 1 cm inside gallbladder; (5) Atrophic gallbladder; (6) Intraluminal stone of gallbladder does not move when change in body position; (7) Regional lymph node enlargement.
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160
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Kang H, Bao G, Dong Y, Yi X, Chao Y, Chen M. [Tensile mechanics of mandibular condylar cartilage]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2000; 18:85-7. [PMID: 12539336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
OBJECTIVE To study the biomechanical properties of the mandibular condyle cartilage and determine its functional importance. METHODS Eight condyle specimens of the four pig temporomandibular joints were obtained by autopsy and stored in sealed plastic bags at -20 degrees C. These pigs were healthy, aged 1 year +/- 2 months. In the coronal direction, 300 microns wide, rectangular cartilage-bone specimens were prepared on the right condyles using specified knife. In the sagittal direction, rectangular cartilage-bone specimens with the same width were obtained on the left condyles. Standard rectangular testing specimens were prepared from cartilage-bone specimens in a microtome kept at -20 degrees C (300 microns wide and 250 microns thick). The specimens were inserted in a soft-tissue uniaxial tensile test machine and immersed in a bath of Ringer's solution at room temperature. Preconditioning of the specimens was carried out prior to the uniaxial tensile experiment and the specimens were elongated to failure with the constant strain rate (0.05 mm/s). The resulting mean values were curved fitted with Fung's two-parameter (A, B) exponential stress strain equation using a nonlinear regression program. RESULTS The data obtained showed that a typical nonlinear biomechanical behavior of the condyle cartilage. Toe-region and quasi-linear zone were obvious on the experimental stress strain relation curve. Theoretically fitted parameter A and B were 0.47 and 4.13 (coronally) and 0.60 and 4.70 (sagittally). The sagittal specimens showed greater tensile stress (2.92 MPa), tensile stiffness (9.04 MPa), energy absorption (6.02 N.mm) but less tensile strain (37.34%) than that of the coronal specimens (2.15 MPa, 6.55 MPa, 4.91 N.mm, and 41.12%). The differences were statistically significant (P < 0.05). CONCLUSION The mandibular condyle cartilage is a kind of biophasic material which shows nonlinear viscoelastic behavior, anistrophic characteristics in biomechanical function and high ability to resist tensile stress in the longitudinal direction.
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Tian M, Yi X, Zeng X, Zeng Q. [Identification of antigens shared between Schistosoma japonicum and Trichinella spiralis]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 2000; 23:225-8. [PMID: 10681743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Cross-reactivity was analysed between the antigen of T. spiralis muscular larvae and antigens of cercariae, liver stage schistosomula, 30 day male and female adult worms of S. japonicum by means of EITB technique. The result showed that the antigens of cercariae schistosomula, female worms except male worms, were recognized by sera from rabbits immunized with T. spiralis antigens or by sera from T. spiralis infected rabbits. The molecular weight of recognized antigens ranges from 15 to 100 kD, mainly from 50 to 70 kD. The immunized rabbit sera and the infected rabbit sera reacted with the same cross-antigens of S. japonicum. Among these schistosome stages, the cercariae showed the most cross-reactive bands, the second were the liver stage schistosomula, and 30 day female worms only showed a weak band which located at 97 kD position. Meanwhile, the anti-S. japonicum sera recognized several T. spiralis antigens which located at 34 kD and above, especially 35-38 kD. The results suggest that there are many antigens shared between T. spiralis and S. japonicum and the main cross-reactive antigens are found in the larva stages of S. japonicum and T. spiralis muscular larva. The cross-reactive antigens are different between various stages of S. japonicum and muscular larva of T. spiralis.
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162
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Yi X, Zeng X, Zhou J, Cai C, Shu X, Yang W, McReynolds L. [Schistosoma japonicum ferritin: cloning, nucleotide sequencing, expression, and purification]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 2000; 23:425-8. [PMID: 10682550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Our previous work showed that immunization of mice with Schistosoma japonicum (Sj) immature eggs induced significant immunity against fecundity and embryonation of the parasite. The Sj adult cDNA library was screened by sera from rabbits against Sj immature egg antigen (RASjIEA). The genes encoding molecules which may induce immunity against fecundity/embryonation were chosen for further cloning and expression. First of all, RASjIEA was absorbed with E. coli lysate to remove cross reactive antibodies. The cDNA library was then immunoscreened using the routine method. The resulted positive plaques were rescreened till individual clones were confirmed. Phagemids were obtained using in vivo excision. The positive clones were amplified using PCR. The sizes of the genes were determined by agarose gel electrophoresis. After DNA sequencing of the genes cloned, Gene bank was searched and six different genes were identified from a total of 102 positive clones. One of six identified genes, Sj ferritin (SjFer) was chosen to subclone into pGMC vector. According to DNA sequences of Sj Fer and MCS (multiple cloning site) of the vector, forward primer (Fer/GMC1) and reverse primer (Fer/GMC2) were designed and used to amplify Sj Fer by PCR. The Sj Fer cDNA and expression vector pGMC were digested with BamHI and XhoI. The digested cDNA and pGMC were ligased by T4 DNA ligase to construct a recombinant which was then used to transform E. coli strain ER2566. The fusion protein GMCSF-Sj Ferritin was expressed in insoluble form, the inclusion body. Pellets were harvested and resolved in Tris-HCl buffer containing 8M urea. GMCSF-Sj Ferritin was purified by affinity chromatography using Ni-NTA resin. The molecular weight was determined by SDS-PAGE. This study first reports the gene encoding S. japonicum ferritin as a new candidate for schistosome vaccine.
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163
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Yi X, Huang-Xian J, Hong-Yuan C. Direct electrochemistry of horseradish peroxidase immobilized on a colloid/cysteamine-modified gold electrode. Anal Biochem 2000; 278:22-8. [PMID: 10640349 DOI: 10.1006/abio.1999.4360] [Citation(s) in RCA: 289] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Direct electron transfer of immobilized horseradish peroxidase on gold colloid and its application as a biosensor were investigated by using electrochemical methods. The Au colloids were associated with a cysteamine monolayer on the gold electrode surface. A pair of redox peaks attributed to the direct redox reaction of horseradish peroxidase (HRP) were observed at the HRP/Au colloid/cysteamine-modified electrode in 0.1 M phosphate buffer (pH 7.0). The surface coverage of HRP immobilized on Au colloid was about 7.6 x 10(-10) mol/cm(2). The sensor displayed an excellent electrocatalytic response to the reduction of H(2)O(2) without the aid of an electron mediator. The calibration range of H(2)O(2) was 1. 4 microM to 9.2 mM with good linear relation from 1.4 microM to 2.8 mM. A detection limit of 0.58 microM was estimated at a signal-to-noise ratio of 3. The sensor showed good reproducibility for the determination of H(2)O(2). The variation coefficients were 3. 1 and 3.9% (n = 10) at 46 microM and 2.8 mM H(2)O(2), respectively. The response showed a Michaelis-Menten behavior at higher H(2)O(2) concentrations. The K(app)(M) value for the H(2)O(2) sensor was found to be 2.3 mM.
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164
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Manoj KM, Yi X, Rai GP, Hager LP. A kinetic epoxidation assay for chloroperoxidase. Biochem Biophys Res Commun 1999; 266:301-3. [PMID: 10600497 DOI: 10.1006/bbrc.1999.1810] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chloroperoxidase exhibits a wide variety of enantioselective epoxidation reactions. Until now, the epoxidation activities have been mainly evaluated using elaborate gas chromatographic methods. This paper reports a rapid and convenient spectrophotometric assay for CPO. The disappearance of indene by catalytic epoxidation is monitored at 250 nm and this is used as an index of enzyme activity. This method will prove to be highly useful in large-scale screening of mutants.
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165
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Yew DT, Yi X, Chan WY, Lam WK. A rabbit model of proliferative vitreoretinopathy induced by injection of astrocytic cultures. Cell Mol Neurobiol 1999; 19:759-73. [PMID: 10456236 DOI: 10.1023/a:1006957123672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. The objective of this study was to decipher whether proliferation of astrocytes and invasion of astrocytic processes into the retina could contribute to retinal detachment in a rabbit model. 2. Cultures of astrocytes were injected intravitreally into the eyes of albino rabbits. 3. Two weeks after injection, proliferation of astrocytes on the retinal surfaces was observed. Vascular endothelial growth factor (VEGF) and proliferative cell nuclear antigen (PCNA) were found by immunohistochemistry to be expressed in the center of the astrocytic growth. 4. Using the same immunohistochemical technique to visualize glial fibrillary acidic protein (GFAP), a marker for astrocytes, processes of astrocytes in the growth were observed to penetrate into the host retina. 5. Retinal detachment was then confirmed by ultrasound, histologically, and grossly 2 weeks after injection of astrocytes. 6. Histochemistry on esterase indicated chloroesterase positive cells inside the growth. The secretion of this form of esterase might soften the vitreous and enhanced retinal detachment. 7. Six weeks after injection, VEGF and PCNA decreased in the astrocytic growth but astrocytic processes still attached onto and penetrated the host retina. 8. This study suggests that astrocytes could be a major factor in inducing retinal detachment.
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Gao C, Li A, Yi X, Feng L. [Applications of porous polymeric materials and its biocompatibility]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 1999; 16:511-5. [PMID: 12552735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
With the barrier materials, guided tissue regeneration materials and hybrid artificial organs as the representafive materials, the applications of polymer skeletal materials in biomedical fields are introduced in this paper. Based on the results of the induced carcinoma, collagenous encapsulation and chronic inflammation around implanted polymers, the effects of polymers topography on biocompatibility are discussed, and the importance of topographical compatibility of materials is emphasized.
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167
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Abstract
Lattice-fluid models describe molecular ensembles in terms of the number of lattice sites occupied by molecular species (r-mers) and the interactions between neighboring molecules. The lattice-fluid model proposed by Sanchez and Lacombe (Macromolecules, 1978;11:1145-1156) was used to model specific retention volume data for a series of n-alkane solutes with n-alkane, polystyrene, and poly(dimethylsiloxane) stationary liquid phases. Theoretical equations were derived for the specific retention volume and also for the temperature dependence and limiting (high temperature) values for the specific retention volume. The model was used to predict retention volumes within 10% for the n-alkanes phases; 22% for polystyrene; and from 20 to 70% for PDMS using no adjustable parameters. The temperature derivative (enthalpy) could be calculated within 5% for all of the solutes in nine stationary liquid phases. The limiting value for the specific retention volume at high temperature (entropy controlled state) could be calculated within 10% for all of the systems. The limiting data also provided a new chromatographic method to measure the size parameter, r, for any chromatographic solute using characteristic and size parameters for the stationary phase only. The calculated size parameters of the solutes were consistent, i.e. independent of the stationary phase and agreed within experimental error with the size parameters previously reported from saturated vapor pressure, latent heat of vaporization or density data.
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Yi X, Mroczko M, Manoj KM, Wang X, Hager LP. Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue. Proc Natl Acad Sci U S A 1999; 96:12412-7. [PMID: 10535936 PMCID: PMC22935 DOI: 10.1073/pnas.96.22.12412] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chloroperoxidase is a versatile heme enzyme which can cross over the catalytic boundaries of other oxidative hemoproteins and perform multiple functions. Chloroperoxidase, in addition to catalyzing classical peroxidative reactions, also acts as a P450 cytochrome and a potent catalase. The multiple functions of chloroperoxidase must be derived from its unique active site structure. Chloroperoxidase possesses a proximal cysteine thiolate heme iron ligand analogous to the P450 cytochromes; however, unlike the P450 enzymes, chloroperoxidase possesses a very polar environment distal to its heme prosthetic group and contains a glutamic acid residue in close proximity to the heme iron. The presence of a thiolate ligand in chloroperoxidase has long been thought to play an essential role in its chlorination and epoxidation activities; however, the research reported in this paper proves that hypothesis to be invalid. To explore the role of Cys-29, the amino acid residue supplying the thiolate ligand in chloroperoxidase, Cys-29 has been replaced with a histidine residue. Mutant clones of the chloroperoxidase genome have been expressed in a Caldariomyces fumago expression system by using gene replacement rather than gene insertion technology. C. fumago produces wild-type chloroperoxidase, thus requiring gene replacement of the wild type by the mutant gene. To the best of our knowledge, this is the first time that gene replacement has been reported for this type of fungus. The recombinant histidine mutants retain most of their chlorination, peroxidation, epoxidation, and catalase activities. These results downplay the importance of a thiolate ligand in chloroperoxidase and suggest that the distal environment of the heme active site plays the major role in maintaining the diverse activities of this enzyme.
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169
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Yi X, Ma Z, Zhang Y. [The relation between cord compression rate and the outcome of surgical treatment]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 1999; 37:610-2. [PMID: 11829906] [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 relation of compressive spinal cord changes in morphology with postoperative results. METHODS 114 cases of operative patients were divided in to three groups: ossification of posterior longitudinal ligament (OPLL), cervical spondylotic myelopathy (CSM), and cervical intervertebral disc herination. The spinal cord plane and to the compressive ratio in the most heavily pressed position were measured according to the JOA record. RESULTS The compressive ratio and the plane were not corelated with clinical history. The spinal cord plane was positively corelated with the recovery rate. CONCLUSIONS The preoperative spinal cord plane in OPLL and CSM is mostly corelated with the recovery rate.
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170
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Tesmer VM, Ford LP, Holt SE, Frank BC, Yi X, Aisner DL, Ouellette M, Shay JW, Wright WE. Two inactive fragments of the integral RNA cooperate to assemble active telomerase with the human protein catalytic subunit (hTERT) in vitro. Mol Cell Biol 1999; 19:6207-16. [PMID: 10454567 PMCID: PMC84565 DOI: 10.1128/mcb.19.9.6207] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have mapped the 5' and 3' boundaries of the region of the human telomerase RNA (hTR) that is required to produce activity with the human protein catalytic subunit (hTERT) by using in vitro assembly systems derived from rabbit reticulocyte lysates and human cell extracts. The region spanning nucleotides +33 to +325 of the 451-base hTR is the minimal sequence required to produce levels of telomerase activity that are comparable with that made with full-length hTR. Our results suggest that the sequence approximately 270 bases downstream of the template is required for efficient assembly of active telomerase in vitro; this sequence encompasses a substantially larger portion of the 3' end of hTR than previously thought necessary. In addition, we identified two fragments of hTR (nucleotides +33 to +147 and +164 to +325) that cannot produce telomerase activity when combined separately with hTERT but can function together to assemble active telomerase. These results suggest that the minimal sequence of hTR can be divided into two sections, both of which are required for de novo assembly of active telomerase in vitro.
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171
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Zhou J, Waine GJ, Zeng Q, Zeng X, Yi X, McManus DP. B-cell epitopes recognized by Chinese water buffaloes (Bos buffelus) on the 22 kDa tegumental membrane-associated antigen (Sj-22) of the Asiatic bloodfluke, Schistosoma japonicum. Vet Res 1999; 30:427-32. [PMID: 10478425] [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] Open
Abstract
The 22.6 kDa tegumental membrane-associated antigen of schistosomes is of recognized importance in immunity to schistosomiasis. In China, bovines are known to play an important role in the transmission of Schistosoma japonicum. Ten buffaloes (Bos buffelus) were vaccinated with a recombinant form (reSj-22) of the S. japonicum 22.6 kDa tegumental antigen (Sj-22) and the sera were used to identify and map possible linear B-cell epitopes on this molecule using a series of 18 overlapping synthetic peptides (P1-P18). Sera from all of the ten vaccinated buffaloes reacted strongly with Sj-22 in western blots and in ELISA, while sera from a further ten adjuvant (Quil A) control buffaloes did not. Four peptides (P3, P8, P9 and P10) were predominantly recognized by at least 90% of the buffalo sera. This pattern of recognition is similar to that obtained in a previous study we undertook in mice immunized with the same antigen whereby peptides 3, 8, 9 and 10 were recognized by over 80% of CBA strain mice. The peptide most frequently recognized by mice (peptide 6), and mapping to an EF-hand calcium binding domain, was recognized by six of the ten vaccinated buffaloes. The major difference between buffaloes and mice occurred with peptide 1 which was recognized very frequently by all three strains of mice tested but was only weakly recognized by three of the ten buffaloes. This study provides a valuable reference for further study on the immunity stimulated by the 22.6 kDa tegumental antigen in the murine model and a natural bovine host of Schistosomiasis japonica.
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172
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Yi X, Tesmer VM, Savre-Train I, Shay JW, Wright WE. Both transcriptional and posttranscriptional mechanisms regulate human telomerase template RNA levels. Mol Cell Biol 1999; 19:3989-97. [PMID: 10330139 PMCID: PMC104358 DOI: 10.1128/mcb.19.6.3989] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/1998] [Accepted: 02/22/1999] [Indexed: 11/20/2022] Open
Abstract
The human telomerase RNA component (hTR) is present in normal somatic cells at lower levels than in cancer-derived cell lines. To understand the mechanisms regulating hTR levels in different cell types, we have compared the steady-state hTR levels in three groups of cells: (i) normal telomerase-negative human diploid cells; (ii) normal cells transfected with the human telomerase catalytic subunit, hTERT; and (iii) cells immortalized in vitro and cancer cells expressing their own endogenous hTERT. To account for the differences in steady-state hTR levels observed in these cell types, we compared the transcription rate and half-life of hTR in a subset of these cells. The half-life of hTR in telomerase-negative cells is about 5 days and is increased 1.6-fold in the presence of hTERT. The transcription rate of hTR is essentially unchanged in cells expressing exogenous hTERT, and the increased steady-state hTR level appears to be due to the increased half-life. However, the transcription rate of hTR is greatly increased in cells expressing endogenous hTERT, suggesting some overlap in transcriptional regulatory control. We conclude that the higher hTR level in cells expressing an endogenous telomerase can be a result of both increased transcription and a longer half-life and that the longer half-life might be partially a result of protection or stabilization by the telomerase catalytic subunit. The 4-week half-life of hTR in H1299 tumor cells is the longest half-life yet reported for any RNA.
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MESH Headings
- Animals
- Blotting, Northern
- Cell Nucleus/metabolism
- Cell Transformation, Neoplastic
- Chromatography, Agarose
- DNA-Binding Proteins
- Epithelial Cells/metabolism
- Fibroblasts/metabolism
- Half-Life
- Humans
- Lung/metabolism
- Mice
- Models, Genetic
- RNA/physiology
- RNA Processing, Post-Transcriptional/physiology
- RNA, Long Noncoding
- RNA, Messenger/metabolism
- RNA, Untranslated
- Retroviridae/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Ribonucleases/metabolism
- Telomerase/genetics
- Telomerase/physiology
- Templates, Genetic
- Time Factors
- Transcription, Genetic
- Transfection
- Tumor Cells, Cultured
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173
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Li Y, Zeng X, Yi X, Tian M. [Detection of different class (subclass) antibodies in sera of patients with schistosomiasis japonica for diagnosis and efficiency evaluation]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 1999; 22:381-3. [PMID: 10073013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The subclass antibodies against IgG1, IgG3 and IgG4 in sera of the patients with chronic Schistosomiasis japonica were detected before treatment, and after treatment--6 and 12 months respectively, using Biotin-Avidin-ELISA (BA-ELISA) established by purified 31/32 KD antigen from the adult worms. At the same time IgG1 and IgM were examined by the standard ELISA. False positive reaction with normal control and cross reaction with other parasitic diseases have not been observed. The IgG1 and IgG3 subclasses showed high sensitivity and specificity and reduced quickly 6 months after treatment. These results indicate that the level of specific IgG1 and IgG4 to the 31/32 KD adult worm protein has high value for diagnosis of Schistosomiasis japonica and evaluation of the curative efficiency of the disease.
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174
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Zeng X, Wang Y, Yi X, Wang S. [Identification of antigens in circulating immune complexes of schistosomiasis japonica]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 1999; 22:377-80. [PMID: 10073012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
In order to identify antigens in circulating immune complexes (CIC) of Schistosoma japonicum, the antiserum against CIC was first successfully prepared by immunization of New Zealand rabbit with CIC isolated from schistosome-infected rabbit sera. The antigens in CIC were identified and analyzed by EITB (enzyme-linked immunoelectro-transfer blot) techniques, using the prepared antiserum against CIC, adult worm antigens (AWA), soluble egg antigens (SEA) and adult excretory antigens (ESA). The results showed that the antiserum against CIC had recognized the AWA bands of 155, 90, 70, 31/32, 20.5, 14 and 8 KD; the SEA bands of 90, 66, 46, 34.5 and 27 KD and the ESA bands of 155, 92, 87.5, 70, 60, 57.5, 50, 46, 36, 31/32, 24, 18.5, 12 and 8 KD. These findings indicate that the antigens in CIC were derived from both schistosome adult worms and eggs. In addition, the localization of the antiserum against CIC targeted antigens in adult worms was also carried out by IFAT (indirect flourescent antibody test). It is suggested that the antigens in CIC were presented mainly in the tegument and the gut of the parasite.
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175
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Zeng Q, Zhou J, Zeng X, Peng X, Zhang S, Yi X. [Cross reaction of Trichinella spiralis larva antigens with sera of schistosomiasis japonica]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 1999; 22:475-7. [PMID: 10072982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Cross reactions of T. spiralis muscular larva antigens (TsMLA) against several sera from patients with other parasitic diseases by ELIB (enzyme-linked immunoblotting technique) were studied. The proteins of 31-100 KDa were recognized by sera of two cases of acute schistosomiasis, while proteins of 44/45, 51/53, 62/64 and 100 KDa were recognized by sera of 11 cases of chronic schistosomiasis. The proteins of 60 KDa showed varied cross reactions against sera of five kinds of patients with other parasitic diseases (filariasis, hookworm diseases, paragonimiasis, ascariasis and clonorchiasis). Only the proteins of 45 KDa were recognized by six of fifteen cases of normal human sera. All of > 29 KDa proteins were recognized by sera of rabbit infected by T. spiralis. It is suggested that there were many antigens in Trichinellen muscular larva which shared in common with several other parasites. The cross reactions of TsMLA against Schistosoma japonicum may be differentiated on the positive reaction bands of 44/45, 51/53, 62/64 and 100 KDa proteins which was specific to the chronic schistosomiasis using the TsMLA by means of ELIB.
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