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Biomedical subjects

L Sun

Publications and source records attributed to L Sun.

At least 199 records · Page 11Linked to original sources
PubMed2000

[Fresh femoral shaft fractures treated with un-reamed intramedullary nail: 203 cases].

OBJECTIVE: To discuss the experience treating fresh femoral shaft fractures with un-reamed intramedullary nail. METHODS: 203 cases of fresh femoral shaft fractures who had been treated with un-reamed intramedullary nail from November. 1995 to January. 1999 were analyzed retrospectively. 18 cases were open, classified as Gustilo I, and. 185 cases were closed. Traction table and image intensifier were used during operation. Closed reduction, un-reamed and free hand distal locking technique were used. Active movements of nearby joints were encouraged and partial weight bearing of 10 - 15 kg were allowed right after operation. RESULTS: All 203 cases of fresh femoral shaft fractures got bone union within 4 - 6 months. No case of delayed union and infection happened. 1 distal locking screw was broken. All patients gained normal extremity functions. CONCLUSION: Un-reamed intramedullary nailing of fresh femoral shaft fracture has less damage to the local soft tissue and blood supply. It has a relative stable fracture fixation, and less interruption to the healing procedure. It is one of the best methods for treating femoral fracture.

Bone Nails↗
PubMed2000

[Geographic information systems spatial analysis on transmission of schistosomiasis in China].

OBJECTIVE: To understand the epidemiologic status and geographical distribution of schistosomiasis in China. METHODS: Relevant detabases were set up after collection of data from two National Sampling Surveys on Schistosomiasis, in 1989 and 1995. Spatial analysis was undertaken after the database linked to the GIS software which was supported by Arc View 3.0a. Correlation analysis was performed to understand the relationship between rates of human infection and cattle infection. RESULTS: The epidemic areas of schistosomiasis with high risk are mainly distributed in the marshland along the Yangtze River and can be identified as five spatial distribution regions based on the results of spatial analysis. Both epidemic areas and positive rates of stool examination in cattle and water buffalo are much wider and higher than that in humans. The positive correlation was seen between infection rate in human and in cattle from data of both sampling surveys. CONCLUSION: The relevant strategy for schistosomiasis control in different spatial regions should be performed accordingly and the measures of control for cattle and water buffalo should be strengthened in the endemic areas.

Adolescent↗
PubMed2000

[Dynamic analysis of junctional sequences of T cell receptor (TCR) delta and gamma gene rearrangement in childhood with acute lymphoblastic leukemia].

OBJECTIVE: To explore the junctional sequence difference of T cell receptor delta and gamma gene rearrangement in childhood acute lymphoblastic leukemia (ALL) at diagnosis, complete remission (CR) and relapse. METHODS: By using the T-vector molecular cloning and sequencing and polymerase chain reaction, the junctional sequences of TCRdeltaV-D and TCRgammaV-J were dynamically analyzed in 34 bone marrow samples of ALL. RESULTS: The junctional sequence of TCR delta, gamma gene showed significant difference and regularity before and after remission and during relapsed periods. The sequence of TCRdeltaV-D were analyzed in 24 samples from ALL. Among them, the intact Vdelta2 and 5'Ddelta3 sequences were observed in 10 samples at diagnosis, of which 7 samples had T-->C mutation in Ddelta3 nonamer sequence. The deletions of rearranged Vdelta2, 5'Ddelta3 and Ddelta3 haptamer sequences were found in 11 complete remission (CR) samples with ALL, but none had T-->C mutation in Ddelta3 nonamer sequence. The deletion rate of Vdelta2 or Ddelta3 sequences and the T-->C mutation in Ddelta3 nonamer sequence were extremely differed between samples at diagnosis and in remission (calculate exact probabilities P = 0.001). The junctional rearrangement sequence of 5'Ddelta3 sequences tended to remain intact in 3 relapsed samples. The findings of TCRgammaV-J sequences were similar to that of TCRdeltaV-D in 10 ALL patients. CONCLUSION: The difference of TCRdeltaV-D and TCRgammaV-J junctional sequences were related to the development, therapeutic effectiveness and outcome in ALL.

Child↗
PubMed2000

[A mutation of platelet glycoprotein I balpha results in defects in its interaction with immobilized vWF].

OBJECTIVE: To study the importance of glycoprotein (GP) I balpha mutation (A156V) in interaction between mutant expressing cell and immobilized vWF under fluid shear stress. METHODS: Mutant GP I balpha cDNA was cloned into the EcoR I site of the mammalian expression vector pDX, mutant cDNA was then transfected into CHO betaIX cells. Human vWF was purified from blood cryoprecipitate by glycine and NaCl precipitation and subsequent separation on sepharose 4B column. The purified vWF was immobilized onto a coverslip. Cell rolling was induced in a parallel-plate flow chamber and observed by phase-contrast video microscope. RESULTS: CHO cells expressing GP I b-IX-V complex could adhere to and roll on immobilized vWF. The A156V mutant cells retained the ability to adhere and roll on vWF matrix, but the rolling speed was significantly faster than that of wild type cells, indicating that the off-rate of the ligand-receptor bond between the mutant and vWF was impaired. Binding of monoclonal antibody AN51 to mutant GP I balpha decreased significantly, indicating that the A156V mutation altered the conformation of the N-terminal ligand-binding region of GP I balpha. CONCLUSION: The mutant GP I balpha has a faster off-rate for its interaction with immobilized vWF. The mutant polypeptide adopts an altered conformation in N-terminal ligand-binding region of GP I balpha. The parallel-plate flow chamber is an extremely useful system in evaluating interaction between GP I balpha and vWF.

Animals↗
PubMed2000

[The sensitivity to apoptosis is enhanced in U937-ASPI-3K cells which stably express antisense ATM/PI-3K].

OBJECTIVE: To analyse the characteristics of apoptosis sensitivity in U937-ASPI-3K cells which is stably expressing anti-sense ATM/PI-3K. METHOD: Annexin V-PI apoptosis detection kid and flow cytometry were used to determine apoptosis rate, Western blot to the expression level of cytochrome C protein and Bcl-2 protein. RESULTS: U937-ASPI-3K cells had a lowered threshold for triggering apoptosis in response to low dose irradiation. Cell apoptosis rate was 28% and (53.0 +/- 5.4)%, respectively, at 8 and 48 hours after 1.5 Gy (137)Cs irradiation, while in U937-pZEOSV2 (+) control group it was 4.2% and (11.0 +/- 3.3)%, respectively. Cytosolic cytochrome C protein band was gradually intensified in U937-ASPI-3K in 4 - 8 h after irradiation, but was not detected in control group. Bcl-2 protein gradually decreased in U937-ASPI-3K in 4 - 8 h after irradiation, but didn't change obviously in control group. CONCLUSION: Cell line U937-ASPI-3K acquired a phenotype with a lowered threshold for triggering apoptosis. It demonstrated that selective inactivation of ATM gene might be of considerable value in tumor treatment.

Apoptosis↗
PubMed2000

[Change of pulmonary circulation in microgravity and simulated microgravity].

Fluid is transferred cephalad in microgravity and simulated microgravity, and the pulmonary circulation is the first to be affected. Blood and fluid contents in the lungs increase, but unevenly distributed among various zones of the lungs. Blood vessels in the lungs are filled and distend. Capillary changes have been observed in the animal model of simulated microgravity. Studies about the changes of regulative function of pulmonary circulation are relatively rare. Observations of the reactivity of pulmonary vessels may help to understand the mechanisms of the changes in pulmonary circulation during microgravity.

Animals↗
PubMed2000

[Osteoarticular allografts for repairing large bone or osteoarticular defects].

OBJECTIVE: To evaluate clinical outcome of bone or osteoarticular allografts. METHODS: From September 1991 to November 1997, large bone or osteoarticular defects secondary to bone tumors resection in 36 patients and severe trauma in 2 patients were repaired by deep frozen or lyophilized allogeneic osteoarticular or diaphysis graft. RESULTS: No obvious immune rejection to the grafts was observed in most of the patients in early stage after operation. The patients were followed up from 1 year and five months to 7 years and five months with an average of 4.2 years. Limb function was satisfactory in 74.19% of the 31 survival patients with large osteoarticular or diaphysis allografts. CONCLUSION: Cryopreserved or lyophilized allogeneic osteoarticular grafts with decreased antigenicity and good biocompatibility are suitable materials for repairing large bone or osteoarticular defects.

Adolescent↗
PubMed2000

[Quality evaluation of indigowoad root and leaf by chemical pattern recognition].

27 samples of indigowoad root and 5 samples of indigowoad leaf from different species and in different habital were collected. The chemical constituents were analyzed by HPLC, and ten original chemical features as a whole obtained. Meanwhile, extrinsic bacteriostasis experiments were carried out for each of the 32 samples. Canonical correlation analysis was applied to the intercorrelation between the chemical and the pharmacologic data, and five chemical features were found to be the effective constituents. In the end, the 32 samples were divided into five classes by the fuzzy clustering technique ISODATA(interachive self-organizing data analysis technique A).

Brassicaceae↗
PubMed2000

[Effect of qiongyugao on the action of DDP in inhibiting the division of GLC-82 cell strain in vitro].

OBJECTIVE: To observe the effect of Qiongyugao (QYG) on the action of DDP in inhibiting the division of GLC-82 cell strain in vitro. METHODS: The method of serum pharmacology was used in observing the morphological change of the cancer cells. By accounting the number of the live cells of each day during 6 days respectively, the growth curve was drawn up. The effects of the three groups on the cancer cells apoptosis of GLC-82 cell strain were analysed by FACS. RESULLTS: The growth of the cancer cells in control group (normal saline) was much better than the other two groups; in chemical therapy group (DDP), the number of the live cells almost kept steady; the number of the live cells in combined group(DDP plus QYG) became even lower. QYG could enhance the action of DDP in inducing the apoptosis of GLC-82 cells strain remarkably. CONCLUSION: QYG can enhance the effects of chemotherapy in inhibiting cancer cells division and inducing their apoptosis.

Adenocarcinoma↗
PubMed2000

[Histological study of the local-regional invasion of pyriform sinus carcinoma].

OBJECTIVE: In order to offer the basis for the operation of the pyriform sinus carcinoma, the local-regional invasion patterns of the pyriform sinus carcinoma were investigated. METHODS: Twenty-six surgical specimens obtained from patients who undergone laryngopharyngectomy were subjected to a whole organ section study. RESULTS: Tumors located in the lateral wall of the pyriform sinus spread mainly towards the lateral wall of the hypopharynx. Tumors located in the inner wall of the pyriform sinus spread mainly towards the larynx and opposite side pyriform sinus, the paraglottic space and thyroid cartilage were particularly frequent invaded. It was rare of the invading of the cricoid cartilage. The invasion of the epiglottis and preepiglottic space across the midline had not been found. There were two invading routines, the paraglottic space and preepiglottic space. The invasion of the paraglottic space was through the aryepiglottic fold and the inner surface of the thyroid cartilage. The invading of the preepiglottic space was through the aryepiglottic fold and the upper part of the inner surface of the thyroid cartilage. CONCLUSIONS: The invading of the preepiglottic space was not the contraindication of the partial laryngectomy. It is practicable to preserve the laryngeal function in most of the patients while tumors located on the lateral or inner wall of the pyriform sinus. There was a tendency to the invading to the contralateral side in the inner wall of the pyriform or postcricoidarytenoid region. Attention should be paid to the submucosal spreading in the postcricoidarytenoid region.

Adult↗
PubMed2000

Effects of XW630 on bone formation in ovariectomized rats and in human osteoblast-like cells.

OBJECTIVE: To study the effects of XW630 on bone formation in overiectomized (OVX) rats and in human osteoblast-like cell line TE85. METHOD: Bone histomorphometric analysis was performed with undecalcified bone sections and tetracycline intraperitoneally labeling. RESULTS: Compared with that of OVX rats, the static data of trabecular bone volume (TBV)/total tissue volume (TTV), TBV/sponge bone volume (SBV) and mean trabecular plate density (MTPD) were enhanced while mean trabecular plate spacing (MTPS) decreased after treated with XW630 for 13w. The dynamic data of single-labeled surface [Sfract(s)], double-labeled surface [Sfract(d)], Sfract(d+1/2s), trabecular osteoid surface (TOS) and bone formation rate in tissue level (Svf) were increased and osteoid maturation period (OMP) shortened in XW630 group. In osteoblast-like cells, both 3H-thymidine incorporation and cell count increased after treated with XW630 for 48. Treated with XW630 for 12 approximately 18h, inducible nitric oxide synthase (iNOS) activity and cGMP content increased in time-dependent manners. CONCLUSIONS: XW630 enhanced bone activation frequency and increased trabecular connectivity, stability, and strength. The cellular mechanism related to effects of XW630 on bone formation in ovariectomized rats.

Animals↗
PubMed2000

[Effects of high dose of dynorphin on NMDA receptor and NOS activities in spinal cord of rats].

OBJECTIVE: To elucidate the effects of N-methyl-D-aspartate(NMDA) receptor and nitric oxide synthase (NOS) activity in dynorphin (Dyn)-induced spinal cord injury. METHODS: The NMDA receptor activity was measured by radio-ligand of 3H-MK801. The constitutive and inducible NOS (cNOS and iNOS) activities were assayed by 3H-arginine conversion. RESULTS: In ventral samples, both 3H-MK801 binding and cNOS activity increased at 0.5 h and persisted for 48 h while iNOS activity enhanced at 4 h after intratheacal injection (i.t.) Dyn A(1-17) at dose of 20 nmol/L. However, the 3H-MK801 binding activity reduced significantly from 4 h to 24 h and cNOS activity did not change at the same time in dorsal samples. 7-nitroindozol (7-NI) and aminoguanidine (AG) inhibited the effects of Dyn A(1-17) (20 nmol/L) on 3H-MK801 binding and NOS activities in ventral samples. N-nitro-L-arginine methyl ester (L-NAME) did not affect the elevation of Dyn A(1-17) on NOS activities but caused 3H-MK801 binding activity reduction in ventral samples. CONCLUSIONS: NMDA-NOS pathway might play important role in Dyn spinal neurotoxicity. NOS inhibitors and Dyn might produce cooperative down-regulation on the function of NMDA-NOS pathway in dorsal cord.

Animals↗
PubMed1999

Design, synthesis, and evaluations of substituted 3-[(3- or 4-carboxyethylpyrrol-2-yl)methylidenyl]indolin-2-ones as inhibitors of VEGF, FGF, and PDGF receptor tyrosine kinases.

Receptor tyrosine kinases (RTKs) have been implicated as therapeutic targets for the treatment of human diseases including cancers, inflammatory diseases, cardiovascular diseases including arterial restenosis, and fibrotic diseases of the lung, liver, and kidney. Three classes of 3-substituted indolin-2-ones containing propionic acid functionality attached to the pyrrole ring at the C-3 position of the core have been identified as catalytic inhibitors of the vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) RTKs. Some of the compounds were found to inhibit the tyrosine kinase activity associated with isolated vascular endothelial growth factor receptor 2 (VEGF-R2) [fetal liver tyrosine kinase 1 (Flk-1)/kinase insert domain-containing receptor (KDR)], fibroblast growth factor receptor (FGF-R), and platelet-derived growth factor receptor (PDGF-R) tyrosine kinase with IC(50) values at nanomolar level. Thus, compound 1 showed inhibition against VEGF-R2 (Flk-1/KDR) and FGF-R1 tyrosine kinase activity with IC(50) values of 20 and 30 nM, respectively, while compound 16f inhibited the PDGF-R tyrosine kinase activity with IC(50) value of 10 nM. Structural models and structure-activity relationship analysis of these compounds for the target receptors are discussed. The cellular activities of these compounds were profiled using cellular proliferation assays as measured by bromodeoxyuridine (BrdU) incorporation. Specific and potent inhibition of cell growth was observed for some of these compounds. These data provide evidence that these compounds can be used to inhibit the function of these target receptors.

Drug Design↗
PubMed1999

TATA element recognition by the TATA box-binding protein has been conserved throughout evolution.

Cocrystal structures of wild-type TATA box-binding protein (TBP) recognizing 10 naturally occurring TATA elements have been determined at 2.3-1.8 A resolution, and compared with our 1.9 A resolution structure of TBP bound to the Adenovirus major late promoter (AdMLP) TATA box (5'-TATAAAAG-3'). Minor-groove recognition by the saddle-shaped protein induces the same conformational change in each of these oligonucleotides, despite variations in promoter sequence that reduce the efficiency of transcription initiation. Three molecular mechanisms explain assembly of diverse TBP-TATA element complexes. (1) T --> A and A --> T transversions leave the minor-groove face unchanged, permitting formation of TBP-DNA complexes on many A/T-rich core promoter sequences. (2) Cavities in the interface between TBP and the minor-groove face of the AdMLP TATA box accommodate the exocyclic NH(2) groups of G in a TACA box and in a TATAAG box. (3) Formation of a C:G Hoogsteen basepair in a TATAAAC box eliminates steric clashes that would be produced by the Watson-Crick base pair. We conclude that the structure of the TBP-TATA box complex found at the heart of the polymerase II (pol II) transcription machinery has remained constant over the course of evolution, despite variations in TBP and its DNA targets.

Amino Acid Sequence↗
PubMed1999

Determination of zolpidem in serum microsamples by high-performance liquid chromatography and its application to pharmacokinetics in rats.

A single-solvent extraction step high-performance liquid chromatographic method is described for quantitating zolpidem in rat serum microsamples (50 microl). The separation used a 2.1 mm I.D. reversed-phase OD-5-100 C18 column, 5 microm particle size with an isocratic mobile phase consisting of methanol-acetonitrile-26 mM sodium acetate buffer (adjusted to pH 2.0 with 40% phosphoric acid) containing 0.26 mM tetrabutylammonium phosphate (13:10:77, v/v/v). The detection limit was 3 ng/ml for zolpidem using an ultraviolet detector operated at 240 nm. The recovery was greater than 87% with analysis performed in 12 min. The method is simple, rapid, and applicable to pharmacokinetic studies of zolpidem after administering two intravenous bolus doses (1 and 4 mg/kg) in rats.

Acetonitriles↗
PubMed1999

Attenuation of virulence in Mycobacterium tuberculosis expressing a constitutively active iron repressor.

Iron is an essential nutrient for the survival of most organisms and has played a central role in the virulence of many infectious disease pathogens. Mycobacterial IdeR is an iron-dependent repressor that shows 80% identity in the functional domains with its corynebacterial homologue, DtxR (diphtheria toxin repressor). We have transformed Mycobacterium tuberculosis with a vector expressing an iron-independent, positive dominant, corynebacterial dtxR hyperrepressor, DtxR(E175K). Western blots of whole-cell lysates of M. tuberculosis expressing the dtxR(E175K) gene revealed the stable expression of the mutant protein in mycobacteria. BALB/c mice were infected by tail vein injection with 2 x 10(5) organisms of wild type or M. tuberculosis transformed with the dtxR mutant. At 16 weeks, there was a 1.2 log reduction in bacterial survivors in both spleen (P = 0.0002) and lungs (P = 0.006) with M. tuberculosis DtxR(E175K). A phenotypic difference in colonial morphology between the two strains also was noted. A computerized search of the M. tuberculosis genome for the palindromic consensus sequence to which DtxR and IdeR bind revealed six putative "iron boxes" within 200 bp of an ORF. Using a gel-shift assay we showed that purified DtxR binds to the operator region of five of these boxes. Attenuation of M. tuberculosis can be achieved by the insertion of a plasmid containing a constitutively active, iron-insensitive repressor, DtxR(E175K), which is a homologue of IdeR. Our results strongly suggest that IdeR controls genes essential for virulence in M. tuberculosis.

Animals↗
PubMed1999

Characterization of two chitinase genes and one chitosanase gene encoded by Chlorella virus PBCV-1.

Chlorella virus PBCV-1 encodes two putative chitinase genes, a181/182r and a260r, and one chitosanase gene, a292l. The three genes were cloned and expressed in Escherichia coli. The recombinant A181/182R protein has endochitinase activity, recombinant A260R has both endochitinase and exochitinase activities, and recombinant A292L has chitosanase activity. Transcription of a181/182r, a260r, and a292l genes begins at 30, 60, and 60 min p.i., respectively; transcription of all three genes continues until the cells lyse. A181/182R, A260R, and A292L proteins are first detected by Western blots at 60, 90, and 120 min p.i., respectively. Therefore, a181/182r is an early gene and a260r and a292l are late genes. All three genes are widespread in chlorella viruses. Phylogenetic analyses indicate that the ancestral condition of the a181/182r gene arose from the most recent common ancestor of a gene found in tobacco, whereas the genealogical position of the a260r gene could not be unambiguously resolved.

Amino Acid Sequence↗