Biomedical subjects

X Cai

Publications and source records attributed to X Cai.

At least 109 records · Page 6Linked to original sources

PubMed1999

[Biological mechanism of macrophage activation by wear particles at the bone-implant interface].

OBJECTIVE: To observe the response of membrane Ca(2+) channel of macrophage-like cells (MCs) to wear particles and analyze the cytoplasmic [Ca(2+)]i change in macrophage activation at the bone-implant interface. METHODS: The synoviocyte system of normal hip joint was established in vitro. Immunohistochemical technique (SABC) with CD68 Mab was used to differentiate MCs and fibroblast-like cells (FCs) in the system, and the time when MCs begin to perform phagocytosis was determined by SEM. 1.5 mg/ml (W/V) Ti alloy, Co-Cr alloy or UHMWPE particles suspension was added into the system to monitor the [Ca(2+)]i change in the MCs by confocal laser scanning microscope (CLSM). RESULTS: Phagocytosis of MCs happened after 6 hours, but within 1 hour the Ca(2+) channel of their cell membrane opened for 1 - 6 times and caused rapid and transient pulses of [Ca(2+)]i in cytoplasm after different period of incubation. There was no significant difference between times or range of the [Ca(2+)]i pulse (P > 0.05). The group of UHMWPE particles had the longest incubation period (P < 0.05), but the interval of pulses was shorter than that in the group of Co-Cr alloy particles (P < 0.05). [Ca(2+)]i pulses still appeared when MCs were incubated by indomethecin (P > 0.05), but the phenomenon could be blocked by nimodipin. CONCLUSIONS: Activation of macrophages at the bone-implant-interface could happen before they phagocytose wear particles. The primary switch-on mechanism of osteolysis mediated by cytokines at the bone-implant interface may be the opening of membrane Ca(2+) channel and pulse-like Ca(2+) influx of macrophages when stimulated by wear particles.

Biocompatible Materials↗

PubMed1999

[Effect of wear particles on cell-to-cell communication of synoviocyte system in vitro and its significance in aseptic loosening of prosthesis].

OBJECTIVE: To study the biological reason of abnormal fiber proliferation at bone-implant interface of aseptically loosened prosthesis by observing cell-to-cell communication of synoviocyte system in vitro under the stimulation of wear particles. METHODS: The synoviocyte system of normal human hip joint was established in vitro and the change of cell-to-cell communication was monitored by fluorescence redistribution after photobleaching technique (FRAP) and confocal laser scanning microscope (CLSM) after Ti alloy, CoCr alloy or UHMWPE particles suspension (1.5 mg/ml, W/V) was added into the system. RESULTS: Cell-to-cell communication of synoviocyte system significantly decreased under the stimulation of three kinds of particles (P < 0.01). he decreased degree was maximal in UHMWPE group and minimal in Ti alloy group (P < 0.01). The cell-to-cell communication level of fibroblast-like-cells (FCs) was significantly lower than that of macrophage-like-cells (MCs) (P < 0.05). CONCLUSIONS: Besides the effect of cytokines promoting fiber proliferation, the great amount of fibrous granuloma at bone-implant interface which has relations with aseptic loosening may be caused by the decrease of cell-to-cell communication of fibroblast under direct stimulation of wear particles.

Alloys↗

PubMed1999

[The application of intraoperative cholangiography in laparoscopic cholecystectomy].

OBJECTIVE: To evaluate the role of intraoperative cholangiography in laparoscopic cholecystectomy (LC). METHODS: Intraoperative cholangiography was attempted in 1 466 patients, and was successfully completed in 1382 patients. The success rate was 94.27%. RESULTS: Stones in the common bile duct in 92 patients, bile duct injury in 8 patients and abnormal bile duct in one patient were found. CONCLUSIONS: Intraoperative cholangiography is an accurate and safe procedure, can provide clear films of biliary tree, and has a high success rate. Its application can reduce the rate of bile duct injury and improve the quality of LC.

Bile Ducts↗

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

[Analysis of products of thymine irradiated by heavy ion beam with capillary gas chromatography].

In this study some chromatographic methods with capillary column, such as GC, GC-MS, GC-FTIR, were used to analyze the products of thymine irradiated by 18O8+ ion beam in N2O saturated aqueous solution. Because of the complexity and small amounts of the products after irradiation by heavy ion beams, it is very difficult to separate them, while with the methods of capillary gas chromatography this problem can be overcome. From the results of GC-MS analysis we can determine the molecular weight of the product, and from the results of GC-FTIR analysis we can get structure information of the product. By this way the products such as 5,6-dihydrothymine, 5-hydroxyl-5-methylhydantoin, 5-hydroxyl-6-hydrothymine, 5-hydro-6-hydroxylthymine, 5-hydroxymethyluracil, trans-thymine glycol, cis-thymine glycol and dimers were determined. Though these products are the same as those from thymine irradiated by gamma ray in N2O saturated aqueous solution, the mechanism of heavy ion beam interact ion with thymine aqueous solution is different from that of gamma ray. The main products from thymine irradiated by 18O8+ ion beam in N2O saturated aqueous solution are formed by hydroxyl additions between 5-6 band of thymine, while those by gamma ray are dimers of thymine.

Electrophoresis, Capillary↗

PubMed1999

[Detection of Plasmodium vivax by polymerase chain reaction in Hainan].

AIM: To establish a modified polymerase chain reaction(PCR) method for the detection of Plasmodium vivax in the endemic areas of malaria and compare the method with the conventional light microscopy in the field. METHODS: A PCR method was modified by improving the collection procedures of blood samples, template extraction, primer design and optimizing the reaction condition. The method was evaluated by examining blood samples from 310 patients with vivax malaria and compared with the conventional light microscopy in endemic areas of Hainan Province. RESULTS: The positive rates of the modified PCR method and microscopic method were 34.2% and 31.9%, respectively. CONCLUSION: The modified PCR method is simple, sensitive and specific for the detection of vivax malaria patients in endemic areas.

Adolescent↗

PubMed1999

[Expression of Schistosoma japonicun fatty acid binding protein gene in silkworm cells and larvae].

AIM: To express the fatty acid binding protein (Sj14FABP) gene of Schistosoma japonicun in the silkworm cells and larvae. METHODS: A 600 bp DNA fragment containing Sj14FABP gene was cloned into baculovirus transfer vector of pBacPAK His1 to construct recombinant transfer vector Sj14-pBac PAK His1. Coinfection was accomplished with this vector and Bombyx mori nuclear polyhedrosis virus (BmNPV) DNA in BmN cells. The recombinant virus of Bm-Sj14 was screened using dot-blotting. The BmN cells and silkworm larvae were infected with Bm-Sj14 to express Sj14FABF gene. Western blotting and ELISA were used to identify the antigenicity of the recombinant protein. RESULTS: Sj14FABP gene was successfully expressed in the BmN cells and silkworm larvae infected with Bm-Sj14. The product was a 18 kDa fusion protein. The yield in BmN cells was about 100 micrograms/1 x 10(6) cells and 33 micrograms/ml cell supernatant. In silkworm larvae, the product yield was 4 mg/ml haemolymph as well as 4.6 mg/g silkworm tissue. The recombinant protein could be recognized by Western blotting and ELISA using the sera from mice immunized with SWAP. CONCLUSION: Sj14FABP gene has been successfully expressed in BmNPV system and the product has high antigenicity.

Animals↗

PubMed1999

[Changes in chloroquine resistance of Plasmodium falciparum in Hainan province].

AIM: To observe the variation in resistance of Plasmodium falciparum after the cessation of chloroquine medication. METHODS: WHO standard in vitro microtest and in vivo test were used. RESULTS: In vitro test showed that the rate of chloroquine-resistant P. falciparum dropped from 97.9% in 1981 to 26.7% in 1997 (P < 0.001). The mean concentration of chloroquine for complete inhibition of schizont formation declined from 10.46 +/- 7.14 pmol/ul blood in 1981 to 1.63 +/- 1.47 pmol/microliter blood in 1997(P < 0.001). In vivo test showed that the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 18.4% in 1997(P < 0.001). The proportion of R III cases to the total resistant cases dropped from 53.1% in 1981 to 14.3% in 1997. CONCLUSION: A tendency of progressive decline of resistance of the parasite was revealed after the cessation of chloroquine medication.

Adolescent↗

PubMed1999

[Use of diagnostic ultrasound of sinus in the paranasal sinus disease].

OBJECTIVE: To utilize the diagnostic A ultrasound of sinuses in the diagnosis of paranasal sinus disease. METHOD: Through history enquirement, careful clinical otorhinolaryngological examination, X-ray examination of paranasal sinus, CT, maxillary sinus puncture and examination of the diagnostic ultrasound of sinus, we observed 115 patients with paranasal sinus disease and compared them with 22 normal people who were in control group. RESULTS: In normal people, the according rate between ultrasound examination and clinicaly diagnostic methods, include history enquirement, otorhinolaryngological examination, X-ray examination, CT and maxillary puncture, is 100%. And in the group of patients with paranasal disease, the according rate is 62.5%-92%. CONCLUSION: The diagnostic A ultrasound of sinus has high accuracy, the control is easy, the cost is relatively lower, it can be used repeatedly and do no harm to the patient's health. It is a good method and assistant technigue in the diagnosis of frontal and maxillary sinus disease.

Adolescent↗

PubMed1999

[Expression and clinical implication of multidrug resistant-associated protein gene (MRP) in patients with laryngeal squamous cell carcinoma].

OBJECTIVE: To study the relationship between the expression of MRP mRNA and the clinical pathological characteristics of the patients with laryngeal squamous cell carcinoma. METHOD: Reverse transcription polymerase chain reaction (RT-PCR) assay was used to detect the expression of MRP mRAN in 35 patients. RESULT: The positive expression rate of MRP mRAN was 45.7 percent (16/35) in laryngeal carcinoma. It was higher in advanced (T3-4) patients than that in early (T1-2) cases (P < 0.05) and showed a significant correlation with metastases of cervical lymph node (P < 0.01). CONCLUSION: It is suggested that the expression of MRP mRNA may not only play an important role in multidrug resistance of laryngeal carcinoma, but also influence their biological behavior of dissemination and metastases.

Adult↗

PubMed1999

[Expression and clinical implication of multidrug resistance gene and multidrug resistant-associated protein gene in patients with hypopharyngeal squamous cell carcinoma].

OBJECTIVE: To study the relationship between the expression of MDR-1 mRNA/P-glycoprotein (P-gp). MRP mRNA and the clinical pathological characteristics of the patients with hypopharyngeal squamous cell carcinoma. METHODS: Reverse transcription polymerase chain reaction(RT-PCR) assay was used to detect the expression of MDR-1 mRNA and MRP mRNA in 25 specimens of the untreated advanced hypopharyngeal carcinoma. Meantime, immunohistochemistry SABC technique was used to test P-gp in 60 tumor specimens. RESULTS: The positive expression rates of MDR-1mRNA and P-gp in hypopharyngeal carcinoma were 48 percent (12/25) and 38.3 percent(23/60), respectively. There was a correlation between expression of MDR-1 mRNA and its product P-gp in 25 patients using RT-PCR assay(P < 0.05). The positive expression rate of MRP mRNA was 52 percent (13/25), which was significantly related to metastases of cervical lymph node (P < 0.01). CONCLUSION: Forty-eight percent of the untreated patients with hypopharyngeal carcinoma presented positive expression of MDR-1 mRNA, which was correlated with its gene product P-gp. The expression of MRP mRNA was associated with increased tumor dissemination and metastases.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

A domain flip as a result of a single amino-acid substitution.

BACKGROUND: The self-assembly properties of beta domains are important features of diverse classes of proteins that include cell-adhesion molecules, surface receptors and the immunoglobulin superfamily. Immunoglobulin light-chain variable domains are well suited to the study of structural factors that determine dimerization, including how residues at the interface influence the preferred dimer arrangement. RESULTS: Single-site mutants of light-chain variable domain Len, designated LenQ38E and LenK30T, formed 'flipped' dimers in which one domain was rotated by about 180 degrees compared with the native protein. The dimer in the native protein is similar to that found between variable domains in Fab immunoglobulin fragments. When compared to the native dimer, more surface area is buried, and more hydrogen bonds and salt bridges are formed between the monomers in the flipped conformation. CONCLUSIONS: Immunoglobulin light-chain variable domains can form a minimum of two distinct quaternary structures. Single-site mutations resulting from changes of one base, such as the exchange of Gln38 to Glu or Lys30 to Thr, change the 'conventional' dimer of protein Len to a flipped arrangement. Native Len is not found in the flipped-domain dimer conformation because it would have excess positive electrostatic potential at the dimer interface that is not compensated by other forces. Excess negative or positive electrostatic potential at the dimer interface can have a determining effect on the mode of dimerization.

Crystallography, X-Ray↗

PubMed1998

(+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl-N- hydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (CMI-392), a potent dual 5-lipoxygenase inhibitor and platelet-activating factor receptor antagonist.

By incorporating an N-hydroxyurea functionality onto diaryltetrahydrofurans, a novel series of compounds was investigated as dual 5-lipoxygenese (5-LO) inhibitor and platelet-activating factor (PAF) receptor antagonist. These dual functional compounds were evaluated in vitro for 5-LO inhibition in RBL cell extracts and human whole blood, and PAF receptor antagonism in a receptor binding assay. PAF-induced hemoconcentration and arachidonic acid- and TPA-induced ear edema in mice were used to determine in vivo activities. The structure-activity relationship analysis to define a preclinical lead is presented. (+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl- N-h ydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (40, CMI-392) was selected for further study. In the arachidonic acid-induced mouse ear edema model, 40 was more potent than either zileuton (a 5-LO inhibitor) or BN 50739 (a PAF receptor antagonist), and it demonstrated the same inhibitory effect as a physical combination of the latter two agents. These results suggest that a single compound which both inhibits leukotriene synthesis and blocks PAF receptor binding may provide therapeutic advantages over single-acting agents. The clinical development of compound 40 is in progress.

Animals↗

PubMed1998

PCR-SSCP of rDNA for the identification of Trichinella isolates from mainland china.

A polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis of the expansion segment 5 (domain IV) of the large subunit of ribosomal DNA was employed to characterize seven isolates of Trichinella from China (A-G), including six of pig origin from regions in Dengxian (A), Tianjin (B), Harbin (D), Baoshan (E), Xinye (F) and Xian (G), and one of canine origin from Changchun (C). Isolates A, D, E, F and G were classified as Trichinella spiralis based on SSCP patterns, while the patterns for isolates B and C were consistent with those of Trichinella nativa or Trichinella T6. The results were supported by random amplified polymorphic DNA (RAPD) analysis using five decamer primers and were in accordance with ecological information for the isolates. Single strand conformation polymorphism results also allowed the direct display of mutational sequence variation in the expansion segment among the five isolates of T. spiralis from China, indicating its usefulness for studying population variation within that species.

Animals↗

PubMed1998

Position 120-123, a potential active site of trichosanthin.

Trichosanthin (TCS) is a type-I ribosome-inactivating protein (RIP) with wide spectrum of biological and pharmacological activities. In the present study, a potential site on the TCS molecule (position 120-123) is identified which may be important for the biological activities of TCS. By using site-directed mutagenesis, position 120-123 of TCS was either deleted or changed from Lys-Ile-Arg-Glu (hydrophilic) to Ser-Ala-Gly-Gly (hydrophobic). Deletion of these residues rendered a TCS molecule completely deprived of ribosome inactivating activity, while hydrophobic replacement caused 4000-fold decrease in ribosome inactivating activity. The abortifacient activity of these two mutants was retained with decreased potency. This implies that position 120-123 of the native TCS molecule plays a critical role in maintaining its biological activity.

Abortifacient Agents, Nonsteroidal↗

PubMed1998

Expression of neuron-specific beta-III tubulin during olfactory neurogenesis in the embryonic and adult rat.

The olfactory neuroepithelium retains the unique capacity to produce a new set of mature neurons every three to four weeks from a precursor population situated at the base of the epithelium. It is not known however, whether developing olfactory neurons in the adult rat follow the same program that is initiated embryonically. By tracking the expression of beta-III tubulin (by immunoreactivity to TuJ-1, an isoform-specific antibody) throughout embryogenesis, we have demonstrated a commitment to the olfactory neuron lineage in a subset of cells in the embryonic olfactory placode and followed their development into adulthood. We have also shown that this developmental pattern of beta-III tubulin expression is recapitulated in neurons undergoing a synchronized neurogenic response to either physical or chemical lesion in the adult neuroepithelium. The embryonic expression pattern reported here is similar to, but earlier than that reported for other markers of developing neurons, such as growth-associated protein-43 and neural cell adhesion molecule. The results of these studies suggest the retention of a conserved neurogenic program from embryonic to adult life in the olfactory neuron and, in addition, support the use of a readily accessible system such as the regenerating olfactory neuroepithelium as an alternative means of studying genes which may be crucial to normal neuronal development.

Animals↗

PubMed1998

Molecular cytogenetic characterization of Thinopyrum and wheat-Thinopyrum translocated chromosomes in a wheat-Thinopyrum amphiploid.

The wheat-Thinopyrum amphiploid 'Agrotriticum # 3425' (AT 3425), which is highly resistant to Cephalosporium stripe, was identified to carry seven pairs of Thinopyrum chromosomes, three pairs of wheat-Thinopyrum translocated chromosomes and 18 pairs of wheat chromosomes. Fluorescence genomic in situ hybridization (FGISH), C-banding, sequential C-banding and FGISH, and denaturing polyacrylamide gel electrophoresis (SDS-PAGE) were used to characterize and identify the chromosomes. The Thinopyrum chromosomes in AT 3425 were designated as T1 through T7 based on their C-banding patterns. The FGISH and C-banding patterns of mitotic chromosomes in AT 3425 and meiotic chromosomes in the hybrid between AT 3425 and wheat cultivar 'Chinese Spring' (CS) revealed that wheat chromosomes 1D, 2B and 3D were involved in the three wheat-Thinopyrum chromosome translocations designated as (W-T)1, (W-T)2, and (W-T)3 respectively. The analysis of high-molecular-weight glutenin subunits in single seeds of AT 3425 confirmed the involvement of wheat chromosome 1D in the translocation (W-T)1. The designations 1DSx1DL-1TL, 2BSx2BL-2TL and 3DSx3DL-3TL were suggested for the wheat-Thinopyrum translocated chromosomes (W-T)1, (W-T)2 and (W-T)3 in AT 3425 respectively.

Chromosome Banding↗

PubMed1998

High-level expression of human interleukin-17 in the yeast Pichia pastoris.

Human interleukin-17 (hIL-17) gene without the signal sequence was isolated from activated peripheral blood lymphocytes by RT-PCR, then highly expressed in the yeast Pichia pastoris in the form of the glycosylated monomer. The monomer of rhIL-17 stimulated mouse fibroblast 3T3 cells to secrete IL-6 and was specifically bound to its receptors on 3T3 cells.

3T3 Cells↗