Biomedical subjects

Jun Yang

Publications and source records attributed to Jun Yang.

At least 55 records · Page 3Linked to original sources

PubMed2006

50-Hertz electromagnetic fields induce gammaH2AX foci formation in mouse preimplantation embryos in vitro.

Effects of electromagnetic fields (EMFs) on DNA damage in mammals are still controversial. In the present study, the effects of EMFs on DNA damage in preimplantation mouse embryos in vitro were investigated by using gammaH2AX foci formation, a new sensitive indicator for detecting DNA double-strand breaks (DSBs). The data obtained demonstrated that EMFs decreased the cleavage rate of preimplantation mouse embryos. This decreasing effect of EMFs was related to the DNA-damaging effect indicated by the induction of gammaH2AX foci formation in preimplantation mouse embryos. The inducing effects of EMFs on gammaH2AX foci formation could be inhibited by the treatment of noise MFs or wortmannin, a phosphatidylinositol 3-kinase (PI3K) family inhibitor. Furthermore, the data obtained also showed that EMFs could activate the DNA damage-repair mechanism by recruiting repair factor Rad50 to the damaged DNA sites to repair the corresponding DNA damage. These findings suggest that EMFs could cause DNA damage in preimplantation embryos in vitro and that the adverse effects of EMFs on development might at least partly act through DNA damage. The DNA damage induced by EMFs could be at least partly repaired by the natural activation of DNA damage-repair mechanism or prevented by the simultaneous treatment of noise magnetic fields.

ATP-Binding Cassette Transporters↗

PubMed2006

Monitoring of organochlorine pesticides using PFU systems in Yunnan lakes and rivers, China.

Polyurethane foam unit (PFU) systems were collected from 11 lakes and three rivers in the Yunnan Plateau, China and, the PFU extrusion liquids were analyzed for organochlorine pesticides (OCPs) by gas chromatography with electron capture detection (GC-ECD). The concentrations of pp'-DDE, HCB and HCHs were undetectable to 1.86 microgl-1 (mean 0.27 microgl-1), undetectable to 0.72 microgl-1 (mean 0.11 microgl-1), and 0.24-21.95 microgl-1 (mean 7.39 microgl-1) respectively in lakes; and those in rivers were undetectable to 0.23 microgl-1 (mean 0.08 microgl-1), 0.68-2.93 microgl-1 (mean 1.70 microgl-1), and 2.71-37.56 microgl-1 (mean 17.01 microgl-1) respectively. Notably, some residue levels of OCPs exceeded the US National Recommended Water Quality Criteria, implying Yunnan has levels of OCPs potentially harmful to human health. Further, the contamination by OCPs showed an obvious spatial distribution pattern. Amongst the lakes, Dianchi, Xingyun, Lugu and Yangzonghai had the highest OCP levels dominated by beta-HCH, whereas among rivers, Nujiang and Lancang Rivers had the highest contents of OCPs dominated by alpha-HCH. This demonstrates that HCHs are the predominant contaminants and some point sources of HCHs may still exist in Yunnan. The pollution levels in Yunnan were compared with other studies, suggesting the PFU method is suitable for long-term on-line monitoring of trace OCPs in aquatic ecosystems. Therefore, continuous studies monitoring OCPs in lakes and rivers are needed to further understand the future trend of contamination.

China↗

PubMed2006

Arginine vasopressin in the caudate nucleus plays an antinociceptive role in the rat.

Our previous work has shown that arginine vasopressin (AVP) regulates antinociception through brain nuclei rather than the spinal cord and peripheral organs. The present study investigated the nociceptive effect of AVP in the caudate nucleus (CdN) of the rat. Microinjection of AVP into the CdN increased pain threshold in a dose-dependent manner, while local administration of AVP-receptor antagonist-d(CH(2))(5)Tyr(Et)DAVP decreased pain threshold. Pain stimulation elevated AVP concentration in CdN perfuse liquid. CdN pretreatment with AVP-receptor antagonist completely reversed AVP's effect on pain threshold in the CdN. The data suggest that AVP in the CdN is involved in antinociception.

Animals↗

PubMed2006

Arylisothiocyanato selective androgen receptor modulators (SARMs) for prostate cancer.

A new series of androgen receptor targeted agents (ARTA) was prepared and tested in androgen-dependent and -independent prostate cancer cell lines. These agents were bicalutamide analogs with isothiocyanato substituted B-rings. Also, the linker sulfone of R-bicalutamide was maintained or replaced with several alternative linkages including ether, amine, N-methylamine, thioether, and methylene (in this case the product was a racemic mixture) functional groups at the X-position. To expand the structure-activity relationship (SAR) of these arylisothiocyanato AR ligands, B-ring halogenated arylisothiocyanato ligands were also prepared and tested. The arylisothiocyanato AR ligands showed strong binding affinities to AR ranging from 0.6 to 54 nM. Among them, thioether and ether linkages demonstrated high binding affinities (0.6 and 4.6 nM, respectively) and selective cell growth inhibition (approximately 3- to 6-fold) for LNCaP, an androgen-dependent prostate cancer cell line, when compared to the androgen independent prostate cell lines (DU145, PC-3, and PPC-1) and a bladder cell line (TSU-Pr1). However, the ligands were inactive (IC50>100 mM) in a normal monkey kidney cell line (CV-1) that was used as the control for non-specific toxicity.

Animals↗

PubMed2006

Self-assembling bisurea macrocycles used as an organic zeolite for a highly stereoselective photodimerization of 2-cyclohexenone.

We report a highly selective 2 + 2 cycloaddition of 2-cyclohexenone in the presence of self-assembled bisurea macrocycles that yields the head-to-tail photodimer. The reaction proceeds with high conversion and with decreased incidence of secondary photorearrangement. Furthermore, the product can be extracted from the assembly, and the solid assembly is readily recovered and reused, much like a zeolite.

Chemistry, Organic↗

PubMed2006

Babesia gibsoni: An apical membrane antigen-1 homologue and its antibody response in the infected dogs.

A cDNA encoding the apical membrane antigen-1 (AMA-1) homologue was obtained by immunoscreening a cDNA expression library prepared from Babesia gibsoni merozoite mRNA. The complete nucleotide sequence of the gene was 2062bp. Computer analysis suggested that the sequence contains an open reading frame of 1794bp with a coding capacity of approximately 66kDa. Based on the homology analysis, this putative protein was designated as B. gibsoni AMA-1 (BgAMA-1). The BgAMA-1 gene was expressed in the Escherichia coli BL21 strain and used as the antigen in Western blotting and the enzyme-linked immunosorbent assay (ELISA). The results indicated that BgAMA-1 was recognized as an immunodominant antigen by the host immune system and that it induced a strong antibody response only in chronic B. gibsoni infection in dogs; however, the antibody response could not be detected in the early infection stage (within 15 days). This phenomenon might be explained by the limited stimulation with the low-abundance protein in the early infection stage. This result shows that BgAMA-1 is a new member of the AMA-1 family and that its immune response is characteristic of canine B. gibsoni infection.

Amino Acid Sequence↗

PubMed2006

Phenotype-genotype correlation in eight Chinese 17alpha-hydroxylase/17,20 lyase-deficiency patients with five novel mutations of CYP17A1 gene.

CONTEXT: P450c17 deficiency (17OHD), caused by mutation in CYP17A1 gene, is characterized by severe hypertension-hypokalemia, sexual infantilism in females, and pseudohermaphroditism in males. We investigated eight Chinese 17OHD patients with five novel mutations of CYP17A1 gene and analyzed phenotype-genotype correlation in a patient with regular menses and seven others with classic presentations by in vitro expression and computer modeling. OBJECTIVE: The objective of the study was to explore the phenotype-genotype correlation in patients with subtle and classic manifestations. SUBJECTS AND METHODS: Eight patients with 17OHD from seven families were diagnosed according to clinical manifestations and basal hormone assays. The CYP17A1 gene was amplified and sequenced. Haplotyping analysis was performed to determine a common ancestor for those subjects with a frequent mutation 1517_1525del. In vitro enzymatic activities assay and computer modeling were used to analyze the phenotype-genotype correlation. RESULTS: Five novel CYP17A1 mutations, homozygous D487_F489del (1517_1525del) and F453S, combined compound Y329K and 1047del, P434L and V310_W313del, and R416C and D487_F489del were identified. Haplotyping showed that 1517_1525del might be inherited from a common ancestor. Compared with the mutations in patients with classical manifestations, F453S in the patient with regular menses, occasional hypertension, and hypokalemia showed a partially reduced 17alpha-hydroxylase (29% of those of wild type) and a minor protein conformational change. CONCLUSION: The clinical manifestations in patients with 17OHD correlate with CYP17A1 mutations and enzymatic activities by in vitro enzyme assay and computer modeling. F453S mutation results in partially reduced enzymatic activities and a subtle phenotype. The prevalent mutation 1517_1525del in Chinese 17OHD patients might be a founder effect.

Adolescent↗

PubMed2006

Acidity of mesoporous MoO(x)/ZrO2 and WO(x)/ZrO2 materials: a combined solid-state NMR and theoretical calculation study.

The acidity of mesoporous MoO(x)/ZrO2 and WO(x)/ZrO2 materials was studied in detail by multinuclear solid-state NMR techniques as well as DFT quantum chemical calculations. The 1H MAS NMR experiments clearly revealed the presence of two different types of strong Brønsted acid sites on both MoO(x)/ZrO2 and WO(x)/ZrO2 mesoporous materials, which were able to prontonate adsorbed pyrine-d5 (resulting in 1H NMR signals at chemical shifts in the range 16-19 ppm) as well as adsorbed trimethylphosphine (giving rise to 31P NMR signal at ca. 0 ppm). The 13C NMR of adsorbed 2-(13)C-acetone indicated that the average Brønsted acid strength of the two mesoporous materials was stronger than that of zeolite HZSM-5 but still weaker than that of 100% H2SO4, which was in good agreement with theoretical predictions. The quantum chemical calculations revealed the detailed structures of the two distinct types of Brønsted acid sites formed on the mesoporous MoO(x)/ZrO2 and WO(x)/ZrO2. The existence of both monomer and oligomer Mo (or W) species containing a Mo-OH-Zr (or W-OH-Zr) bridging OH group was confirmed with the former having an acid strength close to zeolite HZSM-5, with the latter having an acid strength similar to sulfated zirconia. On the basis of our NMR experimental and theoretical calculation results, a possible mechanism was proposed for the formation of acid sites on these mesoporous materials.

Journal Article↗

PubMed2006

Signature patterns revealed by microarray analyses of mice infected with influenza virus A and Streptococcus pneumoniae.

We used cDNA microarrays to identify differentially expressed genes in mice in response to infections with influenza virus A/PR/8/34 (H1N1) and Streptococcus pneumoniae. Expression microarray analysis showed up-regulation and down-regulation of many genes involved in the defense, inflammatory response and intracellular signaling pathways including chemokine, apoptosis, MAPK, Notch, Jak-STAT, T-cell receptor and complement and coagulation cascades. We have revealed signature patterns of gene expression in mice infected with two different classes of pathogens: influenza virus A and S. pneumoniae. Quantitative real-time RT-PCR results confirmed microarray results for most of the genes tested. These studies document clear differences in gene expression profiles between mice infected with influenza virus A and S. pneumoniae. Identification of genes that are differentially expressed after respiratory infections can provide insights into the mechanisms by which the host interacts with different pathogens, useful information about stage of diseases and selection of suitable targets for early diagnosis and treatments. The advantage of this novel approach is that the detection of pathogens is based on the differences in host gene expression profiles in response to different pathogens instead of detecting pathogens directly.

Animals↗

PubMed2006

Regulation of integrin alphaIIbbeta3 activation by distinct regions of its cytoplasmic tails.

The short cytoplasmic tails regulate activation of integrin adhesion receptors via clasping/unclasping of their membrane-proximal helices. Using integrin alpha(IIb)beta(3) as a model, we show that a previously reported activating mutation alpha(IIb)(R(995)D) that perturbs the electrostatic interface in the clasp only partially activates alpha(IIb)beta(3) and that extensive activation of the receptor is achieved by complete deletion of alpha(IIb) CT or triple mutations in alpha(IIb)(V(990)A/F(992)A/R(995)D) that disrupt both electrostatic and hydrophobic interfaces in the clasp. The results provide quantitative evidence for an equilibrium-based integrin activation process where shifting the equilibrium to the fully activated state requires total unclasping of the cytoplasmic tails. We further demonstrate that while the C-terminal region of the alpha(IIb) tail minimally influences alpha(IIb)beta(3) activation, the C-terminal region of the beta(3) tail is critically involved. A disease-causing mutation of S(752)P in this region, but not S(752)A, suppressed partial activation induced by R(995)D or the talin head domain but did not affect activation induced by alpha(IIb) truncation. NMR spectroscopy revealed that S(752)P but not the S(752)A mutation disrupted a C-terminal helix within the beta(3) tail, suggesting that the C-terminal helix may regulate the equilibrium-based clasping/unclasping process. Together, these data provide molecular insights into how distinct regions of the cytoplasmic tails differentially and cooperatively regulate integrin activation.

Amino Acid Sequence↗

PubMed2006

CIB1, a ubiquitously expressed Ca2+-binding protein ligand of the InsP3 receptor Ca2+ release channel.

A family of Ca(2+)-binding proteins (CaBPs) was shown to bind to the inositol 1,4,5-trisphosphate receptor (InsP(3)R) Ca(2+) release channel and gate it in the absence of InsP(3), establishing them as protein ligands (Yang, J., McBride, S., Mak, D.-O. D., Vardi, N., Palczewski, K., Haeseleer, F., and Foskett, J. K. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 7711-7716). However, the neuronally restricted expression of CaBP and its inhibition of InsP(3)R-mediated Ca(2+) signaling when overexpressed (Kasri, N. N., Holmes, A. M., Bultynck, G., Parys, J. B., Bootman, M. D., Rietdorf, K., Missiaen, L., McDonald, F., De Smedt, H., Conway, S. J., Holmes, A. B., Berridge, M. J., and Roderick, H. L. (2004) EMBO J. 23, 312-321; Haynes, L. P., Tepikin, A. V., and Burgoyne, R. D. (2004) J. Biol. Chem. 279, 547-555) have raised questions regarding the functional implications of this regulation. We have discovered the Ca(2+)-binding protein CIB1 (calmyrin) as a ubiquitously expressed ligand of the InsP(3)R. CIB1 binds to all mammalian InsP(3)R isoforms in a Ca(2+)-sensitive manner dependent on its two functional EF-hands and activates InsP(3)R channel gating in the absence of InsP(3). In contrast, overexpression of CIB1 or CaBP1 attenuated InsP(3)R-dependent Ca(2+) signaling, and in vitro pre-exposure to CIB1 reduced the number of channels available for subsequent stimulation by InsP(3). These results establish CIB1 as a ubiquitously expressed activating and inhibiting protein ligand of the InsP(3)R.

Animals↗

PubMed2006

Dose-dependent cell-based assays in V-shaped microfluidic channels.

The capability of lab-on-a-chip technologies in controlling cell transportation, generating concentration gradients, and monitoring cellular responses offers an opportunity to integrate dose-dependent cell-based bioassays on a chip. In this study, we have developed microfluidic modules featured with channel components and sandbag structures for positioning biological cells within the microchip. We have demonstrated that by geometric modulation of the microchannel architectures, it is possible to immobilize individual cells at desired locations with controllable numbers, to generate defined concentration gradients at various channel lengths, and to improve the efficiency and reproducibility in data acquisition. The microfluidic module was used to exercise a series of cell-based assays, including the measurement of kinetics and dynamics of intracellular enzymatic activities, the analysis of cellular response under the stimulation of two chemicals with defined concentration profiles, and the study of laser irradiation effect on cellular uptake of photosensitizers. The results demonstrated the capabilities of the microfluidic module for simultaneously conducting multiple sets of dose-dependent, cell-based bioassays, and for quantitatively comparing responses of individual cells under various stimulations.

Biological Assay↗

PubMed2006

Cocaine- and amphetamine-regulated transcript peptide and sympatho-adrenal axis.

Cocaine- and amphetamine-regulated transcript peptide (CART) is constitutively expressed in discrete regions of the mammalian central and peripheral nervous system. Immunohistochemical studies reveal a well-defined network of CART-immunoreactive (irCART) neurons organized along the sympatho-adrenal axis. Sympathetic preganglionic neurons, but not parasympathetic preganglionic neurons, in the lateral horn area are CART-positive; which in turn innervate postganglionic neurons in the paravertebral and prevertebral sympathetic ganglia as well as the adrenal medulla. A population of chromaffin cells in the adrenal medulla is CART-positive; whereas, postganglionic neurons are not. Sympathetic preganglionic neurons themselves are contacted by irCART cell processes arising from neurons in the arcuate nucleus, the retrochiasmatic nucleus and the rostral ventrolateral medulla. Results from several recent studies suggest CART directly excites neurons along the sympathetic neural axis or indirectly by potentiating the action of glutamate on NMDA receptors, as evidenced by an elevation of blood pressure and heart rate following intracerebroventricular, intracisternal or intrathecal administration of the peptide to anesthetized rats or conscious rabbits.

Adrenal Glands↗

PubMed2006

Biomimetic approach to perophoramidine and communesin via an intramolecular cyclopropanation reaction.

[reaction: see text] Starting from tryptamine 4 and isatin 5, a biomimetic approach to the pentacyclic substructure 1 of perophoramidine and communesin was developed. The key steps were to create a stable three/six bicyclic system 2 on the 2,3-double bond of an indole derivative 3 by an intramolecular cyclopropanation, followed by ring opening of the resulting cyclopropane ring with the in situ generated amine group of an aniline.

Cyclopropanes↗

PubMed2006

Adenomatous polyposis coli (APC) differentially regulates beta-catenin phosphorylation and ubiquitination in colon cancer cells.

Most colorectal cancers have mutations of the adenomatous polyposis coli (APC) gene or the beta-catenin gene that stabilize beta-catenin and activate beta-catenin target genes, leading ultimately to cancer. The molecular mechanisms of APC function in beta-catenin degradation are not completely known. APC binds beta-catenin and is involved in the Axin complex, suggesting that APC regulates beta-catenin phosphorylation. Some evidence also suggests that APC regulates beta-catenin nuclear export. Here, we examine the effects of APC mutations on beta-catenin phosphorylation, ubiquitination, and degradation in the colon cancer cell lines SW480, DLD-1, and HT29, each of which contains a different APC truncation. Although the current models suggest that beta-catenin phosphorylation should be inhibited by APC mutations, we detected significant beta-catenin phosphorylation in these cells. However, beta-catenin ubiquitination and degradation were inhibited in SW480 but not in DLD-1 and HT29 cells. The ubiquitination ofbeta-catenin in SW480 cells can be rescued by exogenous expression of APC. The APC domains required for beta-catenin ubiquitination were analyzed. Our results suggest that APC regulates beta-catenin phosphorylation and ubiquitination by distinct domains and by separate molecular mechanisms.

Adenomatous Polyposis Coli↗

PubMed2006

Electroacupuncture suppresses expression of gastric ghrelin and hypothalamic NPY in chronic food restricted rats.

Electroacupuncture (EA) has been reported to reduce body weight in overweight subjects in clinical practice, as well as in rats and mice with diet-induced obesity. In the present study, this effect of EA was tested in lean rats subjected to long-term food restriction (FR, food was offered only 1 h/day). Two hertz EA administered once every other day produced a further reduction in body weight in FR rats. Exploration of the mechanism involved revealed significant downregulation of the orexigenic peptides: ghrelin in the stomach, and neuropeptide Y (NPY) but not Agouti-related peptide (AgRP) in the hypothalamus, which was in line with the reduction in food intake in rats receiving EA stimulation as compared with those receiving restraint only. Uncoupling protein 3 (UCP3), involved in accelerating energy expenditure, was not significantly altered. These results suggest that the EA-induced body weight reduction was due mainly to a decrease in food intake rather than an increase in energy expenditure. A reduction in the orexigenic peptides ghrelin and NPY may be involved in the underlying mechanism.

Agouti-Related Protein↗

PubMed2006

Reaction of layered sodium disilicate SKS-6 with calcium chloride solution as revealed by solid state NMR spectroscopy: exploring the calcium ion extracting mechanism of SKS-6.

Solid-state 1H, 29Si NMR and 23Na MQMAS NMR spectroscopy combined with X-ray powder diffraction (XRD) technique was used to study the reaction between layered sodium disilicate SKS-6 and calcium chloride solution with different concentrations. Based on the experimental results the calcium ion extracting mechanism of SKS-6 was demonstrated to be via ion replacement, during which calcium ions replace sodium ions and combine with the non-bridging oxygen in SKS-6 for charge compensation, and simultaneously sodium ions leave the interlayer. This ion-replacement process was greatly influenced by the substitution of sodium ions by protons as well as the calcium ions concentration. Increasing calcium ions concentration favors the replacement of sodium ions by calcium ions, but prevents sodium ions from being substituted by protons.

Journal Article↗

PubMed2006

Fabrication of bismuth subcarbonate nanotube arrays from bismuth citrate.

Bismuth subcarbonate ((BiO)2CO3) nanotubes with uniform diameters of about 3-5 nm were fabricated from bismuth citrate; these nanotubes exhibit antibacterial properties against Helicobacter pylori (50% inhibition at 10 microg mL(-1)), a bacterium causing peptic ulcers and gastritis.

Anti-Bacterial Agents↗