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Biomedical subjects

L Yang

Publications and source records attributed to L Yang.

At least 289 records · Page 16Linked to original sources
PubMed2000

[Inhibition of the activation and collagen production of cultured rat hepatic stellate cells by antisense oligonucleotides against transforming growth factor-beta 1 is enhanced by cationic liposome delivery].

In order to investigate the inhibition of the activation and collagen production of cultured rat hepatic stellate cells (HSC) by antisense oligonucleotides (ASON) against TGF beta 1 after cationic liposome (lipofectin) delivery, the authors synthesized a 20-mer phosphorothioate antisense oligonucleotide of TGF beta 1 mRNA, and its sense of missense oligonucleotides, and then treated the HSC with cationic liposome/oligonucleotide complexes respectively. The cellular uptake of 32P-labelled oligonucleotides was determined by liquid scintillation counting, and HSC activation was assessed by the expression of alpha-smooth muscle actin(alpha-SMA). The cellular uptake of lipofectin/32P-ASON complex was approximately five-fold higher than that of 32P-ASON alone. Cationic liposome (lipofectin) delivery significantly increased the inhibition of HSCs activation by ASON, while compared with the use of naked TGF beta 1 ASON at the same concentration (at a final concentration of 1 mumol/L, P < 0.05). However, these effects were not observed in lipofectin alone, liposome/sense or missense oligos complexes at the same concentration. The oligonucleotide or lipofectin/oligos complexes had no cytotoxicity to rat HSCs in culture. These findings suggest that cationic liposome is an effective vehicle to improve the delivery of ASON to rat HSCs in culture, and the cationic liposome/TGF beta 1 ASON complex may be useful for the treatment of hepatic fibrosis.

Actins↗
PubMed2000

[The relationship of cellular DNA content with clinical stage and biological features of colorectal cancer].

The purpose of this study was to explore the relationship of cellular DNA content with clinical stage and biological features of cancer. Flow cytometry was performed on fresh specimens from 86 patients from 1997 to 1998. Forty-five (53.3%) specimens were found to contain cells with abnormal DNA (DNA nondiploidy). Although none of the sex, age, site, differentiation variables correlated with flow cytometric DNA ploidy, nondiploidy was associated with Dukes' stage and lymph node metastasis. Duke's A stage tumors were more frequently diploid than were more advanced tumors, but no difference between Duke's B, C and D stages were observed. These findings suggest that ploidy is associated with some pathological factors.

Aged↗
PubMed2000

[The expression and mechanism study of BMP in pleomorphic adenoma].

OBJECTIVE: One important pathological character of pleomorphic adenomas is that there is chorndriod component in the epithelial tumors. It is well known that bone morphogenetic protein (BMPs) plays important roles in the morphogenesis of hard tissue by inducing mesenchymal cells to differentiate into osteoblasts and chondroblasts in vivo. So we examined the expression of BMP and BMP2 mRNA in pleomorphic adenomas to study the pathological mechanism of chorndriod tissue formation. METHODS: Using ABC immunohistochemistry method, 6 specimens of pleomorphic adenomas were examined with BMP antibody. Reverse transcriptase-polymerase chain reaction (RT-PCR) methods were developed for detecting BMP2 mRNA expression with special primers used to amplify the BMP2 cDNA mature domain fragment. The total RNA was extracted from frozen 6 specimens of pleomorphic adenoma and then reversed to cDNA by reverse transcription using AMV reverse transcriptase. PCR conditions were 94 degrees C for 20 seconds, 60 degrees C for 30 seconds, and 72 degrees C for 1 minute, 40 cycles, followed by extension for 30 minute at 72 degrees C. The reaction products were analyzed by electrophoresis. RESULTS: BMP expression could be found in all of the specimens of pleomorphic adenoma examined by immunohistochemistry method. BMP2 RT-PCR product was detected in only 5 specimens that showed BMP2 mRNA existed in 5 specimens. CONCLUSION: These results may be helpful to study the mechanism of pleomorphic adenoma. It is speculated that BMP secreted by tumor cells may play important roles in origin of osteoid tissue in pleomorphic adenoma by inducing neoplastic myoepithelial cells to differentiate to chondrocytes.

Adenoma, Pleomorphic↗
PubMed2000

[The effect of fibrin sealant on dental pulp for pulp capping in experimental dogs].

OBJECTIVE: To investigate the pulp tissue reaction and reparative dentine formation of dog pulp capped with Fibrin Sealant (FS). METHODS: The fibrin was from a tisseel Kit (Immuno AG, Vienna, Austria) consisting of solution A (freeze-dried human fibrinogen, factor XIII, Aprotinine) and solution B (thrombin powder, calcium chloride) with 0.02 ml from each for each tooth. The Ca(OH)2 paste (Calar, China) was served as the control. Forty nine cuspid, premolar and molar teeth in 4 adult dogs weighed 11-13 kg were used. Surgical anesthesia was obtained by muscle injection of 3% sodium pentobarbital (1 ml/kg). The pulp were exposed by using sterile high-speed rotary cutting instruments with water-cooling. The pulps were treated with 0.02 ml fibrin or Ca(OH)2 paste respectively. The cavity was filled with zine phosphate cement. The animals were killed at intervals of 1, 4, 6, 9 weeks after surgery and perfused with phosphate-buffered saline followed by 10% formalin in phosphate-buffered saline. The jaws were resected and the samples prepared by removing each experimental tooth in block, further fixing them by immersion in 10% formalin in phosphate-buffered saline. The specimen were processed for histologic examination. Serial sections (5 nm thick) were made, stained with hematoxylin and eosin, examined using a light microscope. RESULTS: 7 days after operation, the samples treated with the FS showed no hemorrhage and degeneration of pulp tissue and a small amount inflammatory cells near the wounds. The samples treated with Ca(OH)2 showed hemorrhage and degeneration (2/6) and a large amount inflammatory cells near the wounds. 28 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was nearly recovered. Dentin bridges were observed in 2 out of 6 cases treated with Ca(OH)2. 42 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was totally recovered. Dentin bridges were observed in 2 out of 7 cases of pulp treated with FS and four out of 6 cases treated with Ca(OH)2. 63 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was soundly resumed. The dentine bridge was observed in 4 out 6 cases of pulp treated with the FS and in all 6 cases treated with Ca(OH)2. CONCLUSION: FS has no dentin inducing activity, but can enhance exposed pulp healing, so FS can be served as a promised pulp capping agent.

Animals↗
PubMed2000

[Study on extraction process for psoralen in compound prescription by orthogonal design].

The study on water volume, extraction time and times for the extraction of psoralen in compound prescription Yiniao Tong capsule has been carried out by orthogonal design. The process condition has been determinated, extracting prescription herbs with water for 3 times(2 hour and 16 time amount of water all told). The determination method used in this experiment was TLC-scanning.

Capsules↗
PubMed2000

[Luminescence enhancement of phthalate-Eu-Sr complex].

Using doped method low rare earth concentration and chelates matrix luminescence was successful in the chelates systems. The luminescence of phthalate-Eu-Sr complex is an example. The experimental results show that the complex luminescence would be enhanced co-doped other metal ions(shch as Mn), because other metal ions can transfer energy to rare earth ion. Addition of the second ligand will enhance the complex luminescence, too. In the FTIR spectra of co-doped complexes, the vibrations of nu a(COO-), nu as(COO-), nu CC have shifted, which show that the co-doped metal ions have influence on the molecular structure.

Chelating Agents↗
PubMed2000

[The FAR-IR study of several mono and disaccharides and metal-sugar complexes in solid state].

FIR spectra of saccharides have many peaks. Each saccharide has its characteristic spectrum. The first, the second, the third, the fourth strongest peak appear at different regions(a, b, c, d) and the sequence (the first in a, the second in b, the third in c, the fourth in d) is characteristic. Due to the sequence in relative intensity is different, we use a simple method encoding four strong peaks to distinguish between different saccharides. We divide 500-100 cm-1 into ten ranges and encode each region as follows: 1(100-140 cm-1); 2(141-180 cm-1); 3(181-220 cm-1); 4(221-260 cm-1); 5(261-300 cm-1); 6(301-340 cm-1); 7(341-380 cm-1); 8(381-420 cm-1); 9(421-460 cm-1); 0(461-500 cm-1). For example, the codes of xylose are 6,538 and the codes of d-arabinose are 7 486. Each saccharide has a number. In this way, we can easily differentiate between saccharides. When the complexes have formed, there are broad peaks of M-O. The phenomena illustrate that FIR technique is an useful mean to determine the formation of the complexes and possibly detect their structures.

Disaccharides↗
PubMed1999

Unilateral antegrade cerebral perfusion through the right axillary artery provides uniform flow distribution to both hemispheres of the brain: A magnetic resonance and histopathological study in pigs.

BACKGROUND: Bilateral antegrade cerebral perfusion (ACP) has decreased in popularity over the past decade because of its complexity and the risk of cerebral embolism. We used magnetic resonance (MR) perfusion imaging to assess flow distribution in both hemispheres of the brain during unilateral ACP through the right carotid artery via a cannula placed in the right axillary artery in conjunction with hypothermic circulatory arrest. METHODS AND RESULTS: Twelve pigs were randomly exposed to 120 minutes of either bilateral ACP through both carotid arteries (n=6) or unilateral ACP through the right axillary artery (n=6) at pressures of 60 to 65 mm Hg at 15 degrees C, followed by 60 minutes of cardiopulmonary bypass at 37 degrees C. MR perfusion images were acquired every 30 minutes before, during, and after ACP. The brain was perfusion fixed for histopathology. During initial normothermic cardiopulmonary bypass, MR perfusion imaging showed a uniform distribution of flow in the brain. In both the bilateral and unilateral ACP groups, the same pattern was maintained, with an increase in regional cerebral blood volume during ACP and reperfusion. The changes in regional cerebral blood volume and mean transit time were similar in both hemispheres during and after unilateral ACP. No difference was observed between the 2 groups. Histopathology showed normal morphology in all regions of the brain in both groups. CONCLUSIONS: Both bilateral ACP and unilateral ACP provide uniform blood distribution to both hemispheres of the brain and preserve normal morphology of the neurons after prolonged hypothermic circulatory arrest.

Animals↗
PubMed1999

Feasibility of bioremediation of trichloroethylene contaminated sites by nitrifying bacteria through cometabolism with ammonia.

The autotrophic ammonia-oxidizing bacteria (Nitrosomonas sp.) are able to dechlorinate trichloroethylene (TCE) through cometabolism using ammonia (NH(3)) as a growth substrate. Cometabolic kinetics models suggest that TCE is a potent competitive inhibitor of NH(3) oxidation because it competes with NH(3) for oxidation by the enzyme of ammonia monooxygenase (AMO). In this study, an enriched culture of nitrifying bacteria was used to investigate the efficiencies of cometabolism of TCE by AMO. In addition, the relationships among specific growth substrate (NH(3)) utilization rate (qNH(3)), specific nongrowth substrate (TCE) cometabolic rate (qTCE), NH(3) and TCE concentrations, and NH(3)/TCE and TCE/NH(3) ratios were also analyzed. We found that the relationships between qNH(3) and NH(3) for the systems with and without TCE followed the Alvarez-Cohen competitive inhibition model and Monod model, respectively. Our results demonstrate that TCE could be cometabolized in a nitrification system when sufficient oxygen and NH(3)200 microg/l) were also found to show inhibitory effects towards NH(3) oxidation in enriched nitrifying culture. We also found that the NH(3)/TCE ratio rather than TCE concentrations alone exhibited strong correlation with qNH(3), much the same as the Ely activity recovery model presented. Our results suggest that the relationship between qTCE and TCE concentrations followed the Oldenhuis enzyme inactivation model for systems without NH(3).

Ammonia↗
PubMed1999

[Detection of serum antibody of coxsackievirus A24 variant].

OBJECTIVE: To observe the serum antibody in residents after outbreak of acute hemorrhagic conjunctivitis (AHC) caused by coxrackievirus (CA24 v). METHODS: The serum was diluted in 1:10 and mixed with 100 TCID50 CA24 v in volume. The same the mixture was incubated 1 hour in 37 degrees C and then observed for cytopathic changes of the infected HeLa cells. RESULTS: The post-epidemic antibody positive rate in residents was 49.67% and in 19-25 age group was about 69.49%. It had significant difference statistically (P < 0.01). CONCLUSION: The raising of CA24 v antibody level in residents was relevent with age. May be it was caused by the opporturnities of taking part in social activities in different age groups.

Adolescent↗
PubMed1999

Cellular response to latent TGF-beta1 is facilitated by insulin-like growth factor-II/mannose-6-phosphate receptors on MS-9 cells.

This study was conducted to explore the mechanism of activation of TGF-beta1 which is critical to its role in many physiological and pathological conditions. We have previously demonstrated that latent TGF-beta1 modulates ECM through interaction with IGF-II/M6P receptors on dermal fibroblasts. In this report, we provide evidence that large (270 kDa) but not small (46 kDa) M6P receptors facilitate the cellular response to LTGF-beta1 released from genetically modified cells. As a source of LTGF-beta1, PA317 cells were transfected with either pLin-TGF-beta1 vector or pLin vector with no TGF-beta1 insert using calcium phosphate precipitation. Conditioned medium from transfected cells was removed after 3 days and used to evaluate the latency and bioactivity of TGF-beta1 using ELISA and mink lung epithelial cell growth inhibition assay, respectively. The level of TGF-beta1 was 20-fold greater (2142 +/- 369 vs 102 +/- 23 pg/ml) in conditioned medium derived from pLin-TGF-beta1-transfected cells than in that of controls. Various volumes of this conditioned medium were then used to treat MS-9, SR-2, and MS cells bearing the large, small, and no IGF-II/M6P receptors, respectively, for 24 h. [(3)H]Thymidine incorporation, used as an index for cell proliferation, showed a markedly lower level of proliferation in MS-9 cells in response to a given concentration of LTGF-beta1 than was seen in SR-2 and MS cells. Interestingly, under similar experimental conditions, either addition of M6P at 1 mM concentration or anti-TGF-beta1 antibody abrogated the MS-9 cell proliferative response to LTGF-beta1. In contrast, the inhibitory response of these three cell strains to heat-activated conditioned medium was the same. As another measure of LTGF-beta1-induced cellular response, the expression of mRNA for pro alpha1(I) of type I collagen was also evaluated. A marked increase in expression of this transcript in MS-9 cells in response to LTGF-beta1 was observed. To further examine the possible correlation between the large IGF-II/M6P receptors and cellular responses to LTGF-beta1, expression of IGF-II/M6P receptors at the protein and mRNA levels were evaluated by ligand binding and RT-PCR, respectively. Using (125)I-IGF-II as a ligand, the number of specific IGF-II/M6P receptors was found to be threefold greater on MS-9 than on SR-2 and MS cells. This finding was consistent with the level of IGF-II/M6P receptor mRNA detected by RT-PCR in MS-9 cells. In conclusion, the result of this study shows a direct link between large but not small IGF-II/M6P receptors on MS-9 cells and their response to LTGF-beta1.

Animals↗
PubMed1999

Hormone-independent transcriptional activation and coactivator binding by novel orphan nuclear receptor ERR3.

Orphan nuclear receptors share sequence homology with members of the nuclear receptor superfamily, but ligands are unknown or unnecessary. A novel orphan receptor, estrogen receptor-related protein 3 (ERR3), was identified by yeast two-hybrid screening, using the transcriptional coactivator glucocorticoid receptor interacting protein 1 (GRIP1) as bait. The putative full-length mouse ERR3 contains 458 amino acids and is closely related to two known orphan receptors ERR1 and ERR2. All the ERR family members share an almost identical DNA-binding domain, which has 68% amino acid identity with that of estrogen receptor. ERR3 bound specifically to an estrogen response element and activated reporter genes controlled by estrogen response elements, both in yeast and in mammalian cells, in the absence of any added ligand. A conserved AF-2 activation domain located in the hormone-binding domain of ERR3 was primarily responsible for transcriptional activation. The ERR3 AF-2 domain bound GRIP1 in a ligand-independent manner both in vitro and in vivo, through the LXXLL motifs of GRIP1, and GRIP1 functioned as a transcriptional coactivator for ERR3 in both yeast and mammalian cells. Expression of ERR3 in adult mouse was restricted; highest expression was observed in heart, kidney, and brain. In the mouse embryo no expression was observed at day 7, and highest expression occurred around the 11-15 day stages. Although ERR3 is much more closely related to ERR2 than to ERR1, the expression pattern for ERR3 was similar to that of ERR1 and distinct from that for ERR2, suggesting a unique role for ERR3 in development.

Amino Acid Sequence↗
PubMed1999

Dysregulated myelopoiesis in mice lacking Jak3.

Jak3 is a cytoplasmic tyrosine kinase that associates with the common chain of the interleukin-2 (IL-2) receptor and is involved in the function of the receptors for IL-2, IL-4, IL-7, IL-9, and IL-15. Mice deficient in Jak3 have few T and B cells, and no natural killer cells. Herein we show that the myeloid lineages in these mice are also affected by the loss of Jak3. Mice lacking Jak3 exhibit splenomegaly by 4 months of age. Peripheral blood smears show an increase in the number of neutrophils and cells of the monocytic lineage. Flow cytometry of splenocytes and peripheral blood show a significant increase in FcgammaRII/III(FcgammaR)/Mac-1, FcgammaR/Gr-1, and FcgammaR/F4/80 double-positive cells in -/- and +/- mice compared to wild-type mice, consistent with an expansion of cells of the myeloid lineages. In addition, as the mice age, F4/80 and CD3 positive mononuclear cells infiltrate the kidneys, lungs, and liver of these mice. When Jak3-/- mice are crossed with a transgenic mouse expressing Jak3 in the T and NK cell compartments, the splenomegaly and myeloid expansion are accentuated. These data correlate with the constitutive activation of T cells in the periphery as the transgenic cells lose their expression of Jak3 with age. However, when Jak3-/- mice are crossed with RAG-1-deficient animals, no splenomegaly or myeloid expansion is apparent. These results indicate that the loss of Jak3 in the T-cell compartment drives the expansion of the myeloid lineages.

Animals↗
PubMed1999

HIV-specific cytotoxic T lymphocyte precursors exist in a CD28-CD8+ T cell subset and increase with loss of CD4 T cells.

OBJECTIVES: To determine whether the CD28-CD8+ T cells that develop during HIV infection contain HIV-specific cytotoxic precursor cells. DESIGN: CD8 subpopulations from six asymptomatic HIV-positive adults, with varying degrees of CD4 T cell loss, were sorted by flow cytometry and HIV-specific precursor cytotoxic T lymphocyte frequencies were measured. Three populations of CD8 T cells were tested: CD28+CD5-- T cells, CD28-CD57+ T cells (thought to be memory cells) and CD28-CD57- T cells (function unknown). METHODS: Sorted CD8 subsets were stimulated with antigen presenting cells expressing HIV-1 Gag/Pol molecules. Cytotoxic T cell assays on Gag/Pol expressing 51Cr-labeled Epstein-Barr virus transformed autologous B cells lines or control targets were performed after 2 weeks. Specific lysis and precursor frequencies were calculated. RESULTS: Both CD28 positive and CD28-CD57+ populations contained appreciable numbers of precursors (9-1720 per 10(6) CD8+ T cells). However, the CD28-CD57- population had fewer precursors in five out of six people studied. More CD28 positive HIV-specific cytotoxic T lymphocyte precursors were found in patients with CD4:CD8 ratios > 1, whereas more CD28-CD57+ precursors were found in patients whose CD4:CD8 ratios were < 1 (r2, 0.68). CONCLUSIONS: Memory HIV-specific precursor cytotoxic T lymphocytes are found in both CD28 positive and CD28-CD8+ cells, however, a CD28-CD57- subpopulation had fewer. Because CD28-CD57+ cells are antigen-driven with limited diversity, the loss of CD28 on CD8 T cells during disease progression may reduce the response to new HIV mutations; this requires further testing.

Adult↗
PubMed1999

Evidence for epitope spreading and active suppression in skin graft tolerance after donor-specific transfusion.

BACKGROUND: To clarify the controversial results in the literature regarding the role of donor-specific transfusion (DST) on allograft survival, we have examined the influence of the following on DST-induced allograft survival in a 2C transgenic mouse model: varying the time between DST and transplantation; the role of MHC disparities between donor and recipient; whether tolerance induced by DST spreads to skin allografts expressing other alloantigens; and whether cyclosporine (CsA) treatment could further modulate skin allograft tolerance after DST. METHODS AND RESULTS: The studies were performed in both 2C anti-Ld (MHC class I) transgenic and normal (nontransgenic) mice. Our data demonstrate that a single infusion of Ld-mismatched lymphocytes 7 days before transplantation leads to permanent acceptance of donor-specific skin allografts in both transgenic (58/58) and nontransgenic (8/8) mice in the absence of any other nonspecific immunosuppressive treatment. Pretransplantation DST from donors mismatched for more than one MHC antigen (Ag) has no beneficial effect on subsequent donor skin allograft survival. However, Ld plus multiple minor histocompatibility (mH) Ag-mismatched DST induced permanent acceptance of donor-specific skin allografts. Tolerance induced by one-locus Ld-mismatched DST spreads to skin allografts expressing either two-locus Ld or one-locus Ld plus multiple mH Ags. Administration of CsA after DST diminished skin allograft survival, rather than enhancing it, suggesting that tolerance in this model system is established by an active immunological process sensitive to CsA. CONCLUSIONS: (1) Pretransplantation infusion of Ld-mismatched lymphocytes in the presence or absence of multiple mH mismatches induces permanent survival of donor-specific skin allografts. (2) CsA abrogates DST-induced transplantation tolerance.

Animals↗
PubMed1999

Binding of Photosurfactant (4-butyl-azobenzene-4'-oxyethyltrimethylammonium bromide) to Polyelectrolyte.

The binding of a photosurfactant, 4-butyl-azobenzene-4'-oxyethyltrimethyl ammonium bromide (BZTABr), to a linear polymer, sodium poly(2-acrylamide-2-methylpropane sulfonate) (PAMPS), has been studied by using a surfactant selective electrode. The photosurfactant undergoes a trans-cis transition on UV/vis irradiation. The binding behavior changes by varying the composition of the trans and cis forms in the solution. The ideal mixing-ideal cooperative binding model we had proposed previously for the binding of binary surfactants was applied to successfully predict the binding isotherms and the critical aggregation concentrations of the present systems. The binding of a trans-cis mixture of BZTABr to a polymer is analogous to the ideal mixed micelle formation. A sort of synergetic effect was found in the binding process. Copyright 1999 Academic Press.

Journal Article↗