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Biomedical subjects

Y Xu

Publications and source records attributed to Y Xu.

At least 595 records · Page 33Linked to original sources
PubMed1999

[Isolation and identification of two flavonoids from Taraxacum mongolicum Hand.-Mazz].

OBJECTIVE: To study the chemical constituents of Taraxacum mongolicum. METHOD: Compounds were separated by column chromatography on silica gel and polyamide, and their structures were determined by spectral analysis and chemical evidence. RESULT: Two flavonoid compounds were separated and elucidated as isoquercitrin and hyperin. CONCLUSION: These two compounds were isolated from the plant for the first time.

Flavonoids↗
PubMed1999

[The treatment to esophagus stricture with Ni-Ti shape memory alloy stand(with the report of 19 clinical cases)].

OBJECTIVE: To discuss the use of Ni-Ti shape memory alloy stand in treating the stricture of esophagus. METHOD: After finding the stricture part of esophagus under X-ray, the metal guide string was put through the esophagoscope. Dilatation of esophagus was performed firstly. Then the inserting instrument, which has the Ni-Ti shape memory alloy stand inside, was put through the stricture part along the metal guide string and the stand which can return to its original shape automatically was released. Barium meal examination of esophagus was performed after the operation to determine the site of the stand and to realize the smooth degree of esophagus. RESULT: All 19 patients got a successful operation at one time. They swallowed freely after the operation. The effective rate was 100%. CONCLUSION: Ni-Ti shape memory alloy stand can dilate the stricture of esophagus quickly, improve swallowing function obviously. The operation can be easily performed. The therapeutic effectiveness is reliable, and there is no serious complication. This can be used as a routine method in treating the stricture of esophagus.

Adolescent↗
PubMed1999

[Vascular bundle specific expression of iaaL gene affects the generation frequencies of transgenic tobacco].

A vascular bundles specific expressing vector pBAL1 with a promoter AQ630 from rice phenylalanine ammonialyase gene and a gene encoding indoleacetic-lysine synthytase from Pseudomonas syringae subsp. savastanoi was constructed. Affirmed by Southern blotting and RTPCR analysis, the AQ630-iaaL transgenic plants show increasing shoots-regeneration frequency of young stem explants on hormone-free 1/2 MS medium and lower sensibility to IAA when roots were induced from the root explants on the media containing different concentrations of IAA compared to untransformed plants.

Culture Techniques↗
PubMed1999

[The prospects of research on VR rehabilitation engineering].

In this paper, we present the recent development of Vitual Reality (VR) technology and rehabilitation engineering and discuss the rationality and feasibility of the application of VR to rehabilitation. With VR technology, psychological induction can be better introduced in rehabilitating exercises and patients can be tremendously released from fret during traditional physical training for rehabilitation. The VR is expected to bring about a technological revolution in rehabilitation engineering.

Computer Simulation↗
PubMed1999

[Some basic techniques of virtual reality body healthiness vehicles for rehabilitation].

Some know-how techniques of virtual reality rehabilitation vehicles are discussed in this paper after a brief introduction of the application background and the structure and functions of the vehicles. This kind of vehicles can be used for psychological treatment during rehabilitation. Pateints can select different modes of physical exercises according to their individual situations, and therefore they can get rehabilitation much faster and more easily than those under the traditional treatments.

Computer Simulation↗
PubMed1999

[Construction of full-length cDNA clone and complete nucleotide sequence of RNA2 of cucumber mosaic virus SD strain].

The full-length cDNA clone of CMV-SD RNA2 was constructed from two cDNA clones, which were obtained by RT-PCR with primers synthesized based on terminal sequences determined using 5' RACE and 3' RACE, respectively; and the complete sequence was determined. It consists of 3048 nt and there are two partial overlapped ORFs. ORF1, which is located in the 5' portion (79-2652 nt), codes for 2a protein of 858aa, and GDD consensus sequence reported to be "polymerase site" was found in deduced 2a protein sequence. ORF2, which is located in the 3' portion (2414-2746 nt), codes for 2b protein of 111aa. The overall nucleotide sequence homologies with RNA2 of CMV Fny and Q strain, which are representatives of subgroups I and II, respectively, are 91.7% and 75.6%; the amino acid sequence homologies are 93.8% and 67.7% for 2a protein, and 83.0% and 51.3% for 2b protein, respectively. These results demonstrated that CMV-SD belongs to subgroup I.

Amino Acid Sequence↗
PubMed1999

[Induction of protective immunity in mice against Schistosoma japonicum by nucleic acid vaccine encoding the full-length paramyosin].

AIM: To investigate the immune efficacy of nucleic acid vaccination in mice against full-length paramyosin of Chinese Schistosoma japonicum. METHODS: C57BL/6 and BALB/c mice were vaccinated intramuscularly with the nucleic acid vaccine (pCMV-SjC97) encoding the full-length gene of paramyosin of Chinese S. japonicum. Each group was immunized three times at weeks 0, 3 and 6. Mice vaccinated with pCMV blank vector served as negative control. Mice were challenged three weeks after final DNA boosting by percutaneous infection with cercariae. Six weeks after infection the mice were perfused, worm burden and eggs in the livers, spleens and intestines were counted. Sera from vaccinated mice were collected from the tail vein at weeks 0, 3, 6 and 9, respectively. RESULTS: C57BL/6 mice vaccinated with pCMV-SjC97 produced predominantly IgG2a and IgG2b; whereas in BALB/c mice, IgG1, IgG2a and IgG2b antibodies. Immunization with the pCMV-SjC97 in C57BL/6 mice could confer significant worm reduction rate (35.5%-41.4%, P < 0.05) and egg reduction rate (liver: 44.5%-59.6%, P < 0.05; spleen: 56.7%-82.4%, P < 0.05; intestines: 57.9%, P < 0.05), but not in BALB/c mice. CONCLUSION: The nucleic acid vaccine, pCMV-SjC97, could induce protective immunity in C57BL/6 mice significantly.

Animals↗
PubMed1999

[Establishment and identification of the monoepitopic monoclonal antibody of Plasmodium falciparum].

AIM: To prepare a monoepitopic monclonal antibody of Plasmoduim falciparum. METHODS: According to the theory of protein structure, a peptide with 6-9 residues representting the antigenicity of the original histidine-rich protein II (HRP-II) of P. falciparum was synthesized and used to immunize BALB/c mice after purity identification by capillary electrophoresis. RESULTS: Four hybridoma cell lines targeting a suitable peptide from pf HRP-II were obtained by using spleen embedment method and hybridoma technology. CONCLUSION: It is the first report to prepare a monoepitopic monoclonal antibody against original protein by selecting a suitable peptide from the primary sequence of protein.

Animals↗
PubMed1999

[Cloning, sequencing and expression of the full-length gene encoding paramyosin of Schistosoma japonicum in vivo].

AIM: To clone and sequence the gene encoding paramyosin of S. japonicum (Chinese strain) and to study the expression of the DNA-based vaccine encoding the full-length paramyosin of S. japonicum in vivo. METHODS: Total RNA was isolated from adult S. japonicum using TRIzol reagent. The full-length cDNA encoding paramyosin of S. japonicum was amplified by RT-PCR and cloned into pGEM-T vector and sequenced by the method of dideoxy-mediated chain-termination. The cDNA encoding paramyosin of S. japonicum was subcloned into the expressive plasmid vector pCDNA/AMP(pCMV-Sjc97), and the recombinants were identified by restriction enzyme digestion and sequencing. The immunofluorescence assay was used to study the expression of Sjc97 in vivo in mice. RESULTS AND CONCLUSION: The 2.6 kb cDNA encoding the full-length paramyosin of Chinese S. japonicum has been successfully cloned and sequenced for the first time. The full-length sequence of paramyosin of S. japonicum was determined. Comparison of the nucleotide sequence and the deduced amino acid sequence of Sjc97 with that of S. japonicum paramyosin (Philippine strain) (Sjp97), S. japonicum paramyosin(Japanese strain) (Sjj97), S. mansoni (Sm97), B6 and Y6 clone (the partial cDNA encoding paramyosin of Chinese strain) showed that Sjc97 differed from Sjp97 by 16/2,601 nucleotide and 3/866 amino acid substitutions (99.4% on nt-level and 99.7% on aa-level in homology); from Sjj97 by 20/2,601 nucleotide and 2/866 amino acid substitutions (99.2% on nt-level and 99.8% on aa-level in homology); and from B6 by 11/1,329 nucleotide and 1/443 amino acid substitutions (99.0% on nt-level and 99.8% on aa-level in homology); from Y6 by 13/1,329 nucleotide and 1/443 amino acid substitutions (98.9% on nt-level and 99.8% on aa-level in homology); Sjc97 differed from the Sm97 by 2,235/2,601 nucleotide and 34/866 amino acid (91.0% on nt-level and 96.0% on aa-level in homology). The plasmid expression vector encoding the full-length paramyosin of Chinese S. japonicum has been successfully constructed. The pCMV-Sjc97 vaccine could express Sjc97 protein in vivo in mice after intramuscular immunization.

Amino Acid Sequence↗
PubMed1999

[Evaluation of immunochromatographic test in the diagnosis of Plasmodium falciparum and Plasmodium vivax].

AIM: To evaluate the effectiveness of immunochromatographic test(ICT) in detecting Plasmodium falciparum and Plasmodium vivax in malaria endemic areas. METHODS: ICT was used to detect P. falciparum and P. vivax among patients with fever in the outpatient clinics by comparason with thick blood smear method. RESULTS: The sensitivity of ICT to detect P. falciparum and P. vivax was 96.7% and 90.4%, respectively. The specificity of ICT was 98.6%, and the coincidence rate was 94.7%. There is no cross reaction between P. falciparum and P. vivax. CONCLUSION: ICT could detect P. falciparum and P. vivax simutaneously, being more rapid and simple than blood smear method.

Animals↗
PubMed1999

[Studies on the features of protective immune response induced by recombinant Sjc26GST of Schistosoma japonicum].

AIM: To compare the differences in the protective immune response induced by reSjc26GST between C57BL/6 and BALB/c mice. METHODS: Mice were immunized subcutaneously with reSjc26GST emulsified with Freund's adjuvant. The specific antibody isotypes elicited by reSjc26GST, in vitro lymphocyte proliferation and cytokine responses to reSjc26GST were examined. RESULTS: The level of anti-reSjc26GST IgG was higher in immunized C57BL/6 mice than in BALB/c mice, and examination of the IgG subclasses demonstrated that reSjc26GST-immunized C57BL/6 mice resulted in predominantly IgG1 and IgG2a/IgG2b antibody responses, whereas in BALB/c mice, IgG1 antibody. Cytokine production assays revealed that the quantity of IFN-gamma and IL-2 and IL-5 released from the reSjc26GST-primed splenocytes were significantly higher in C57BL/6 mice than in BALB/c mice. These results showed that the immunization with reSjc26GST in C57BL/6 mice elicited a mixed immune reaction of Th1 and Th2 cell responses as demonstrated by the elevated levels of IgG1, IgG2a/IgG2b and IL-2, IFN-gamma, IL-5, whereas in BALB/c mice, reSjc26GST immunization elicited Th2 response as demonstrated by the elevated levels of IgG1, IL-2 and IFN-gamma. CONCLUSION: Immunization with reSjc26GST could elicit higher humoral and cellular immune responses in C57BL/6 mice than in BALB/c mice.

Animals↗
PubMed1999

[Anti-hemolytic and anti-membranous lipid peroxidation effects of daphnetin].

AIM: To investigate the anti-hemolytic and anti-membranous lipid peroxidation effects of daphnetin. METHODS: The inhibition rates of daphnetin on AQD-induced hemolysis and erythrocytic membranous lipid peroxidation were determined by routine in vitro assay for detecting hemolytic toxicity and by HPLC for detecting membranous lipid peroxidation products. RESULTS: Daphnetin at a range of 10-80 mumol/L inhibited dose-dependently AQD-induced hemolysis and lipid peroxidation by 33.0%-69.2% and 11.9%-58.2%, respectively. CONCLUSION: Daphnetin has anti-hemolytic and anti-erythrocytic membranous lipid peroxidation effects.

Aminoquinolines↗
PubMed1999

[Observation on the dynamics of specific anti-GST antibodies in rabbits immunized with recombinant 26 kDa GST of Schistosoma japonicum].

AIM: To investigate the dynamics of the anti-GST antibodies in rabbits immunized with recombinant 26 kDa GST of Schistosoma japonicum. METHODS: The specific antibodies were detected weekly by GST-ELISA in rabbits vaccinated with purified recombinant 26 kDa GST antigen of S. japonicum plus FCA/IFCA; rabbits immunized with 0.85% saline plus FCA/IFCA served as control group. RESULTS: The specific anti-GST antibodies began to increase at week 4 post-immunization, the mean OD value in rabbits vaccinated with recombinant GST could reach 1.03 +/- 0.46 (adjuvant control group only 0.42 +/- 0.04). The experiment was completed at week 65 post-immunization when the mean OD values for specific anti-GST antibody in immunized rabbits were 0.94 +/- 0.26(0.29 +/- 0.16 in the control group). CONCLUSION: Strong anti-GST antibody responses could be induced in rabbits vaccinated with recombinant 26 kDa GST of S. japonicum.

Animals↗
PubMed1999

[Effects of blocking the TGF alpha-EGFR autocrine loop on the growth of human pancreatic carcinoma cells in vitro].

OBJECTIVE: Investigate the effects of blocking the TGF alpha-EGFR autocrine loop on the growth of human pancreatic carcinoma. METHODS: The pCMV-AS-EGFR, a recombinant vector expressing antisense EGFR under the control of human CMV promotor was constructed and transfected the transformant PC-7/AS-TGF alpha cell line cells, which had been transfected by a recombinant retroviral vector expressing antisense TGF alpha. G418 resistant colonies were isolated and identified as PC-7/AS-TGF alpha/AS-EGFR. The integration and expression of exogenous and endogenous genes were detected by Southern blot and Northern blot analysis. Apoptosis was detected by DNA fragmentation, flow cytometry and in situ cell death detection. RESULTS: The cells which were double-transfected by the recombinant vectors showed the integration and expression of exogenous genes, and the downregulation of endogenous EGFR and cyclin D1 mRNA. 125I-EGF ligand binding test showed the binding affinity of the EGFR on the cell surface also reduced. The inhibition effect of cotransfecting of antisense TGF alpha and antisense EGFR was remarkable as compared with that of antisense TGF alpha alone. The incorporation rate of 3H-TdR reduced from 25% to 14.5%, and the growth inhibition rate increased from 78.6% to 86.0%. The ability of soft agar colony-formation was completely suppressed. CONCLUSIONS: These observations strongly support that the blockage of the expression of autocrine growth factor TGF alpha and its receptor EGFR was a potent way in circumventing the malignant properties of the pancreatic carcinoma cells.

Cell Division↗
PubMed1999

[Studies on localization of laryngeal carcinoma associated antigen by immunoelectromicroscopy].

OBJECTIVE: To study the localization of laryngeal carcinoma associated antigen (LCAA) in the carcinoma tissue. METHODS: Ninety cases of laryngeal carcinoma and 14 cases of laryngeal precancerous lesion and 10 cases of normal laryngeal mucosa were detected with three strains of monoclonal antibodies LC9, LC11, LC12 by immunochemistry. The positive sections of laryngeal carcinoma were observed under light microscope and electromicroscopy. RESULTS: The positive rates of LCAA were dramatically higher than that in normal epithelial and precancerous tissues (P < 0.01). The results showed that the mixed monoclonal antibody had tissue specificity. The MLC associated antigens only distributed in cell membranes and/or cytoplasm. No cell nucleus was stained. CONCLUSION: The LCAA is mainly located in cell membranous structure. This study may provide morphological basis for immunoimaging diagnosis and targeting chemotherapy by application of laryngeal carcinoma McAb.

Antigens, Neoplasm↗
PubMed1999

[The expression of Ras protein in human middle ear cholesteatoma].

OBJECTIVE: To evaluate the possible role of Ras protein in acquired middle ear cholesteatoma. METHODS: The specimens from the acquired middle ear cholesteatoma tissue of 22 cases and the normal external ear skin of 10 cases were examined by immunohistochemical S-P method and computer image analysis. RESULTS: All epithelial layers of cholesteatoma revealed a relatively abundant expression of Ras protein, among which 15 cases showed an inner plasma membrane expression, 5 cases a cytoplasm and membrane expression, and 2 cases cytoplasm expression only. In contrast, the normal external ear skin revealed a sparse distribution of Ras protein in the inner plasma membrane of epithelial cells with a more intensely staining in the basal layer. The integral absorbency of Ras protein in the two types of tissues were 0.870 and 0.463 respectively with a significant difference between them. CONCLUSION: There is an aberrant regulation of Ras protein in cholesteatoma. Ras protein plays a pivotal role during the aberrant growth and the differentiation of cholesteatoma.

Adolescent↗