Biomedical subjects

P Yang

Publications and source records attributed to P Yang.

At least 199 records · Page 11Linked to original sources

PubMed1998

Effects of dietary manganese on arterial glycosaminoglycan metabolism in Sprague-Dawley rats.

The objectives of this study were to determine whether dietary manganese deficiency alters total glycosaminoglycan (GAG) concentration and composition and glycosyltransferase activity in rat aortas. Sprague-Dawley rats were fed either a manganese-deficient or a manganese-sufficient diet. Arterial GAGs were isolated and quantified by measuring uronic acid content. The individual GAGs were separated and quantified with cellulose acetate electrophoresis. The activity of the enzyme galactosyltransferase I was measured using a 100,000 g particulate fraction and 4-methylumbelliferylxyloside (Xyl-MU) as an acceptor. There was a significant decrease (p < or = 0.05) in uronic acid content in the manganese-deficient (1.18 +/- 0.08 mg/g) rat aortas as compared with the manganese-sufficient (1.59 +/- 0.10 mg/g) ones. Chondroitin sulfate and heparan sulfate concentrations were decreased by 38% (p < or = 0.01) and 36% (p < or = 0.05), respectively, in the manganese-deficient rat aortas. The incorporation of UDP-galactose to acceptors by the manganese-deficient rat aorta preparations was increased by 28% as compared to the manganese-sufficient preparations. These results indicate that manganese is involved in arterial GAG metabolism by affecting the enzyme galactosyltransferase and that changes in GAG concentration and composition with manganese deficiency may ultimately affect arterial wall integrity and subsequently cardiovascular health. This is the first work to demonstrate that manganese nutrition is important in arterial GAG metabolism.

Animals↗

PubMed1998

Stepwise dynamics of connecting filaments measured in single myofibrillar sarcomeres.

Single relaxed myofibrils of bumblebee flight muscle were subjected to motor-imposed ramp-length changes. The image of the striations was projected onto a linear photodiode array, and sarcomere length was computed as the spacing between centroids of contiguous A-bands. Centroid position was determined by integrating the respective A-band intensity peak and computing the location at which the area on one side was equal to the other. The resulting trace of centroid to centroid span versus time was stepwise, with periods of rapid shortening alternating with periods of pause. An alternative nondiscrete sensor gave similar steps. If thick filament length remains constant, stepwise sarcomere length changes imply that length changes in the connecting filament must be stepwise. Thus, shortening of the connecting filament occurs as a sequence of discrete events rather than as a continuous event.

Animals↗

PubMed1998

Induction of specific T-cell tolerance by adenovirus-transfected, Fas ligand-producing antigen presenting cells.

A major problem associated with adenovirus gene therapy is the T cell-mediated immune response, which is elicited by inoculation of the adenovirus vector and leads to rapid clearance of the virus and loss of transgene expression. In this study, the immune response to adenovirus was prevented by induction of specific T-cell tolerance by pretreatment with adenovirus-infected antigen-presenting cells (APC) that express Fas ligand. Compared with control-treated mice, the tolerized mice showed prolonged expression of lacZ upon administration of AdCMVlacZ 1 week after tolerance induction. In contrast to the control mice, the tolerized mice did not display proliferation of CD3+ T cells in the spleen in response to AdCMVlacZ. Tolerance induction also was indicated by the lower production of interferon-gamma and interleukin-2 by peripheral T cells isolated from AdCMVlacZ-challenged tolerized mice than by AdCMVlacZ-challenged control-treated mice. The T-cell tolerance was specific for the adenovirus as the T-cell responses to irrelative murine cytomegalovirus remained unimpaired. Our results indicate that adenovirus-specific T-cell tolerance can be induced by APCs that coexpress Fas ligand and adenovirus antigens. We propose that this new strategy can be used to induce tolerance to adenovirus vector gene therapy with resultant prolonged expression of the transgene.

Adenoviridae↗

PubMed1998

An oligo selection procedure for identification of sequence-specific DNA-binding activities associated with the plant defence response.

Sequence-specific DNA-binding (SSDB) factors play central roles in transcription, DNA replication, recombination and repair. This report describes a simple procedure for high-throughput identification of SSDB activities without prior knowledge of their target genes or binding sequences. The procedure starts with a population of completely random oligo(nucleotide) sequences and selects for those oligo molecules that specifically bind to cellular SSDB factors by use of common gel-retardation assays and PCR. Amplification and subsequent cloning of these selected oligo molecules result in the establishment of oligo DNA libraries enriched in DNA molecules containing specific sequences recognized by SSDB factors. These oligo libraries can be rapidly screened to identify a large number of SSDB activities, including those that are differentially regulated by developmental and environmental signals. With identified oligo DNA as probes, the corresponding SSDB factors can be isolated and analysed with respect to their structures, regulation and functions. Using this procedure, we have identified approximately 100 SSDB activities from tobacco leaves, including seven that are differentially regulated during the tobacco mosaic virus-induced hypersensitive response in resistant tobacco plants.

Amino Acid Sequence↗

PubMed1998

Escherichia coli and Proteus mirabilis inhibit the perinuclear but not the circulating antineutrophil cytoplasmic antibody reaction.

BACKGROUND: Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) are found in 48%-83% of serum samples from patients with ulcerative colitis (UC). Their pathogenic role and initiating stimuli are unknown. In contrast to patients with vasculitides and ANCA reactivities, the antibodies in UC patients do not react with myeloperoxidase (MPO) or proteinase 3 (PR3). The aim of the present study was to investigate whether bacterial species of the intestinal tract and other sources could interfere with P-ANCA in sera from patients with UC. METHODS: Seventeen P-ANCA-positive and anti-MPO-negative serum samples from patients with UC were tested with Escherichia coli 014 and Staphylococcus aureus Wood 46. Six of these serum samples with different P-ANCA titres were selected to test further the influence of 15 different gram-negative or gram-positive bacterial strains. Six anti-MPO positive P-ANCA, 5 anti-PR3 positive C-ANCA, and 10 antinuclear antibody (ANA)-positive serum samples were used as controls. The antineutrophil cytoplasmic antibodies (ANCAs) were analysed by an indirect immunofluorescence method (IIF) on ethanol-fixed neutrophils, and the ANAs were tested by IIF on HEp-2 cells or rat liver tissues. The bacteria used in the experiments were either live or killed by formalin or glutaraldehyde fixation or heated at 80 degrees C for 30 min. The test was first performed as a bacterial absorption test with sedimented organisms and then at various temperatures with the supernatant from suspension of live bacteria. RESULTS: Both MPO-positive and MPO-negative P-ANCA reactivity was abolished by absorption of patient sera with live E. coli and Proteus mirabilis but not with bacteria representing members of 10 other species, suggesting that antibody reactivity was absorbed away. However, continued experiments indicated that the inhibition of P-ANCA was not due to classic antigen-antibody interactions but rather to decomposition of the antigenic substrate of the neutrophils by factors present in the supernatants of live E. coli and P. mirabilis. The activity of the supernatant was temperature-dependent, with strong activity at room temperature and 37 degrees C, no activity at 0 degrees C, and abolished by mild heat treatment (56 degrees or 60 degrees C). No activity was shown in the supernatants from bacteria treated with formaldehyde or glutaraldehyde. CONCLUSIONS: Soluble material from live E. coli and P. mirabilis has the capacity to decompose the antigenic substrate of neutrophils responsible for both MPO-positive and MPO-negative P-ANCA, most probably brought about through enzymatic activity. Anti PR3-positive C-ANCA were not affected, which suggests substrate specificity of the proposed enzymatic activity.

Adult↗

PubMed1998

Gas chromatograph/isotope dilution mass spectrometric analysis of airborne benzo

A critical evaluation has been made of the gas chromatography/isotope dilution mass spectrometry (GC/IDMS) analysis of airborne benzo[a]pyrene (B[a]p) using 2H-(deuterium, D) and 13C-labeled benzo[a]pyrene and a low resolution mass spectrometer. Laboratory quality control and field samples were used to determine the suitability of these two isotopically labeled B[a]p as surrogates for GC/IDMS B[a]p analysis. With method spike QC samples, recovery of the B[a]p was compared with the recoveries of D- and 13C-labeled B[a]p to validate the assumption that these two isotopically labeled B[a]p analogs could be used as method surrogates for IDMS B[a]p analyses. Two collocated Anderson Hi-Vol samplers were used to carry out a field study in which total B[a]p loadings from one sampler were correlated to the second sampler, before and after correcting the total B[a]p loadings against the recovery of the D- and 13C-labeled B[a]p. It is shown that a low-resolution mass spectrometer can be used in GC/IDMS B[a]p analysis to achieve results of high precision and accuracy. Depending on data quality objectives, D-labeled B[a]p could be used for IDMS B[a]p analysis, but is not recommended.

Journal Article↗

PubMed1998

The Mr 140,000 intermediate chain of Chlamydomonas flagellar inner arm dynein is a WD-repeat protein implicated in dynein arm anchoring.

Previous structural and biochemical studies have revealed that the inner arm dynein I1 is targeted and anchored to a unique site located proximal to the first radial spoke in each 96-nm axoneme repeat on flagellar doublet microtubules. To determine whether intermediate chains mediate the positioning and docking of dynein complexes, we cloned and characterized the 140-kDa intermediate chain (IC140) of the I1 complex. Sequence and secondary structural analysis, with particular emphasis on beta-sheet organization, predicted that IC140 contains seven WD repeats. Reexamination of other members of the dynein intermediate chain family of WD proteins indicated that these polypeptides also bear seven WD/beta-sheet repeats arranged in the same pattern along each intermediate chain protein. A polyclonal antibody was raised against a 53-kDa fusion protein derived from the C-terminal third of IC140. The antibody is highly specific for IC140 and does not bind to other dynein intermediate chains or proteins in Chlamydomonas flagella. Immunofluorescent microscopy of Chlamydomonas cells confirmed that IC140 is distributed along the length of both flagellar axonemes. In vitro reconstitution experiments demonstrated that the 53-kDa C-terminal fusion protein binds specifically to axonemes lacking the I1 complex. Chemical cross-linking indicated that IC140 is closely associated with a second intermediate chain in the I1 complex. These data suggest that IC140 contains domains responsible for the assembly and docking of the I1 complex to the doublet microtubule cargo.

Amino Acid Sequence↗

PubMed1998

The Chlamydomonas IDA7 locus encodes a 140-kDa dynein intermediate chain required to assemble the I1 inner arm complex.

To identify new loci that are involved in the assembly and targeting of dynein complexes, we have screened a collection of motility mutants that were generated by insertional mutagenesis. One such mutant, 5B10, lacks the inner arm isoform known as the I1 complex. This isoform is located proximal to the first radial spoke in each 96-nm axoneme repeat and is an important target for the regulation of flagellar motility. Complementation tests reveal that 5B10 represents a new I1 locus, IDA7. Biochemical analyses confirm that ida7 axonemes lack at least five I1 complex subunits. Southern blots probed with a clone containing the gene encoding the 140-kDa intermediate chain (IC) indicate that the ida7 mutation is the result of plasmid insertion into the IC140 gene. Transformation with a wild-type copy of the IC140 gene completely rescues the mutant defects. Surprisingly, transformation with a construct of the IC140 gene lacking the first four exons of the coding sequence also rescues the mutant phenotype. These studies indicate that IC140 is essential for assembly of the I1 complex, but unlike other dynein ICs, the N-terminal region is not critical for its activity.

Animals↗

PubMed1998

The herpesvirus transactivator VP16 mimics a human basic domain leucine zipper protein, luman, in its interaction with HCF.

In human cells infected with herpes simplex virus (HSV), viral gene expression is initiated by the virion protein VP16. VP16 does not bind DNA directly but forms a multiprotein complex on the viral immediate-early gene promoters with two cellular proteins: the POU domain protein Oct-1 and host cell factor (HCF; also called C1, VCAF, and CFF). Despite its apparent role in stabilizing the VP16-induced transcription complex, the natural biological role of HCF is unclear. Only recently HCF has been implicated in control of the cell cycle. To determine the role of HCF in cells and answer why HSV has evolved an HCF-dependent mechanism for the initiation of the lytic cycle, we identified the first human ligand for HCF (R. Lu et al., Mol. Cell. Biol. 17:5117-5126, 1997). This protein, Luman, is a member of the CREB/ATF family of transcription factors that can activate transcription from promoters containing cyclic AMP response elements (CRE). Here we provide evidence that Luman and VP16 share two important structural features: an acidic activation domain and a common mechanism for binding HCF. We found that Luman, its homolog in Drosophila, dCREB-A (also known as BBF-2), and VP16 bind to HCF by a motif, (D/E)HXY(S/A), present in all three proteins. In addition, a mutation (P134S) in HCF that prevents VP16 binding also abolishes its binding to Luman and dCREB-A. We also show that while interaction with HCF is not required for the ability of Luman to activate transcription when tethered to the GAL4 promoter, it appears to be essential for Luman to activate transcription through CRE sites. These data suggest that the HCF-Luman interaction may represent a conserved mechanism for transcriptional regulation in metazoans, and HSV mimics this interaction with HCF to monitor the physiological state of the host cell.

Animals↗

PubMed1998

Interferon gamma immunoreactivity in iris nerve fibres during endotoxin induced uveitis in the rat.

AIMS: Previous studies have implied that interferon gamma (IFN-gamma) is involved in the pathogenesis of endotoxin induced uveitis (EIU) in the rat. This study investigated the source of IFN-gamma in the iris during EIU. METHODS: Whole mounts of iris were isolated from Lewis rats before and at different times (from 4 hours to 14 days) after foot pad injection of 200 micrograms Salmonella typhimurium lipopolysaccharide (LPS). Immunohistological analysis was performed using monoclonal antibodies (mAbs) specific to rat IFN-gamma (DB12 and DB13). mAbs specific to monocytes, macrophages, and dendritic cells and MHC class II were used to asses the inflammatory response in the eye (ED-1, ED-2, and OX-6). An antibody specific to neurofilaments (2H3) was used to stain nerve fibres in the normal iris. RESULTS: LPS administration induced acute intraocular inflammation, characterised by a massive infiltration of monocytes/macrophages and increased numbers of MHC class II positive cells in the iris. IFN-gamma immunoreactive cells were not detected in iris whole mounts of control rats. Strikingly, IFN-gamma immunoreactivity was found in fibres from 4 hours until 10 days after LPS injection, with the most intense staining at 48-72 hours. Other DB12 or DB13 positive cells were not detected in the iris. The pattern of DB12 and DB13 staining in the inflamed iris was similar to the 2H3 staining of neurons in the iris of control rats. CONCLUSION: These results show that systemic LPS administration induces IFN-gamma immunoreactivity in iris fibres and suggest that iris nerve fibres may be a source of IFN-gamma during EIU. The IFN-gamma immunoreactive material in the iris nerve fibres may be identical to neuronal IFN-gamma.

Animals↗

PubMed1998

Analysis of loss of heterozygosity on chromosome 11 and infrequent inactivation of the MEN1 gene in sporadic pituitary adenomas.

To investigate the role of tumor suppressor genes in sporadic pituitary adenomas, we first analyzed loss of heterozygosity on 11q13 with microsatellite analysis in 31 tumors. Loss of heterozygosity on 11q13 was detected in 1 mixed GH/PRL adenoma, and the somatic 22-bp deletion of the multiple endocrine neoplasia type 1 (MEN1) gene encoding menin was detected in this tumor. Trisomy 11 suggested by the decreased mean allelic ratios of 66% or 65% for 16 or 13 microsatellite markers, respectively, in 2 of 31 pituitary adenomas was confirmed by interphase fluorescence in situ hybridization. Screening for mutations of the MEN1 gene did not find mutations with PCR-single strand conformation polymorphism analysis in other pituitary adenomas retaining heterozygosity on 11q13. Based on these, it is concluded that inactivation of the MEN1 gene comprises a rare etiology for tumorigenesis of the pituitary gland, and that trisomy 11 or another gene(s) may contribute to the pathogenesis of sporadic pituitary adenomas.

Adenoma↗

PubMed1998

Immunohistochemical studies on the endotoxin-induced uveitis.

OBJECTIVE: To investigate the longitudinal changes of macrophages and major histocompatibility complex (MHC) class II-positive cells in the iris and ciliary body of Lewis rats after lipopolysaccharide (LPS) injection. METHODS: Immunohistochemistry was performed using monoclonal antibodies to monocytes and macrophages (ED1) and MHC class II-positive cells (OX6) on wholemounts of the iris and ciliary body in endotoxin-induced uveitis (EIU). RESULTS: A network of macrophages (ED1+ cell) and MHC class II-positive cells, was present in the iris and ciliary body of normal Lewis rats. Most cells in the iris and ciliary body displayed dendritiform appearance. A severe involvement of the iris and ciliary body, as evidenced by a rapid influx of monocytes and macrophages and remarkable increase of MHC class II-positive cells, was observed after LPS injection. CONCLUSIONS: A network of macrophages and MHC class II-positive cells in the iris and ciliary body may play an important role in immune surveillance. LPS injection induces a severe inflammation in the anterior segment of the eye, which may serve as a model for acute anterior uveitis in human.

Animals↗

PubMed1998

[Study of experimental mixed bone marrow transplantation].

OBJECTIVE: To explore strategies for preventing graft versus host disease (GVHD) while preserving graft versus leukemia (GVL) effects in allogeneic bone marrow transplantation(BMT). METHODS: Allogeneic bone marrow and spleen cells mixed with syngeneic spleen/bone marrow cells were transplanted into lethally irradiated inbred mice. The mortality of the recipient mice from GVHD, the number of CFU-S, the origin of the bone marrow cells responsible for the reconstitution at different time after transplantation and the proliferative reaction against the stimulating cells from the syngeneic or allogeneic mice were observed and compared with those in the conventional syngeneic and allogeneic BMT. L615 leukemia model was used to evaluate the GVL effect of mixed BMT. RESULTS: Lethal GVHD was effectively prevented by the syngeneic spleen cells which showed no harmful effect on the CFU-S reconstitution. The medium survival time of the mixed transplanted L615 mice was significantly prolonged. CONCLUSION: The grafts composed of allogeneic bone marrow and spleen cells mixed with syngeneic spleen cells, make the recipient mice have transient GVL effects resulted from the MHC mismatched immunocompetent cells and alleviated the severe GVHD of allogeneic BMT.

Animals↗

PubMed1998

[TNF-alpha production and antitumor effect of rhIL-2-activated bone marrow cells].

OBJECTIVE: To explore the mechanism of the cytotoxic effects of bone marrow cells activated with recombinant human interleukin-2(rhIL-2). METHODS: The cytotoxicity of rhIL-2-activated bone marrow (ABM) and the TNF-alpha level in the supernant of ABM culture were measured after activated for 24 and 48 hours. RESULTS: The cytotoxic activity against HL-60 cells and the level of TNF-alpha were significantly increased in ABM as compared with that in non-ABM(P < 0.01). Meanwhile, there was a significantly positive relationship between the TNF-alpha levels in supernant and cytotoxicities of ABM. CONCLUSION: TNF-alpha produced by rhIL-2 activated bone marrow cells involved in the antitumor effect of ABM.

Bone Marrow Cells↗

PubMed1998

[Effect of substance P on the short-circuit current of nasal mucosal epithelium].

OBJECTIVE: To observe the changes of epithelial apical membrane short-circuit current (Isc) of antigen-sensitized rat nasal mucosa with the stimulation of Substances P (SP). METHODS: The epithelial apical membrane Isc were measured with Ussing chamber technique, and and we observed the blockage to the effect of SP by neurokinin receptor antagonist Cp96345, histamine H1 receptor antagonist pyrilamine, H2 antagonist ranitidine and neurotoxin respectively. RESULTS: The Isc increased significantly with the stimulation of SP. The effect of SP on Isc could be blocked significantly by pretreatment with four substances. CONCLUSION: SP releasing from nervous endings plays the role on elicit a series of pathological changes like enhanced Isc, epithelial permeabilities, etc.

Animals↗

PubMed1998

[Application of capillary electrophoresis in speciation analysis].

Each species has different chemical and biological behaviors. Toxicity is often dependent on it. So element speciation is important in a variety of environmental, biological, geological, and medical applications. Recently, capillary electrophoresis(CE) has been applied to speciation analysis owing to its high efficiency and short analysis time. This paper reviews the applications of CE-UV and CE-ICP-MS in speciation analysis and discusses some related problems.

Arsenic↗

PubMed1998

[8-chloroadenosine inhibits the growth factor-induced proliferation of retinal pigment epithelial cells in vitro].

OBJECTIVE: To study the inhibitory effect of 8-chloroadenosine (8-Cl-A) on growth factor-induced proliferation of retinal pigment epithelial (RPE) cells in vitro. METHODS: Primary culture and subculture of bovine RPE cells were established in vitro first and then tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), basic fibroblast growth factor (bFGF) plus different concentrations of 8-Cl-A (2-16 micromol/L) were added to the cells of third passage respectively. DNA synthesis in RPE cells was measured with (3)H-TdR incorporation. RESULTS: Cells treated with TNF-alpha, IL-1beta, bFGF had a higher (3)H-TdR uptake than the basal. The increase was abolished by 8-Cl-A in a dose dependent manner (P < 0.05). At TNF-alpha, IL-1beta, bFGF with 8-Cl-A group, CPM was similar to basal at 16, 8, 2 micromol/L respectively (P > 0.05). CONCLUSION: 8-Cl-A can inhibit the three growth factor-induced proliferation of RPE cells.

2-Chloroadenosine↗

PubMed1998

[Immunohistochemical studies on wholemounts of the cornea and iris-ciliary body after corneal transplantation].

OBJECTIVE: To study the phenotype of the cells involved in the pathogenesis of allograft rejection after corneal transplantation. METHODS: Wholemounts of the cornea and iris-ciliary body were isolated and prepared from normal rats and those after penetrating corneal transplantation. Immunohistochemical stainings were carried out on these wholemounts using monoclonal antibodies to CD3 (T cell), CD4 [T-helper (Th) cell], CD8 [T-suppressor (Ts) cell], macrophages, dendritic cells, B lymphocytes, major histocompatibility complex (MHC) class II antigen and transforming growth factor-beta (TGF-beta). RESULTS: All the cells mentioned above except B lymphocytes were positive and present in a small number in the peripheral cornea and limbus of normal rats. A massive influx of CD3, CD4, CD8 positive cells, macrophages, dendritic cells, MHC class II and TGF-beta positive cells not only into cornea but also into the iris was observed 7 days after allograft corneal transplantation. Whereas no B cell was found in the allograft. Such a cellular response was not found in the rats in which corneal transplantation with autologous cornea was performed. CONCLUSION: T cells, Th cells, Ts cells, macrophages, dendritic cells, MHC class II positive cells and TGF-beta positive cells are involved in the pathogenesis of corneal allograft transplantation. The involvement of the iris and ciliary body may promote or aggravate the allograft rejection.

Animals↗