Biomedical subjects

Xiaoying Zhang

Publications and source records attributed to Xiaoying Zhang.

16 recordsLinked to original sources

PubMed2026

APOM-associated inflammation and apoptosis in stroke-exacerbated myocardial infarction: implications for brain-heart interactions.

Brain-heart syndrome (BHS) describes cardiac dysfunction secondary to central nervous system injury, with acute ischemic stroke (AIS) serving as a critical driver that exacerbates myocardial infarction (MI). This study aimed to elucidate the role of Apolipoprotein M (APOM) in stroke-aggravated MI and to explore its underlying systemic and molecular mechanisms. Clinical data were analyzed to evaluate the correlation between stroke and MI. A combined mouse model of middle cerebral artery occlusion (MCAO) and MI was established to assess neurological and cardiac injury. Quantitative proteomics and Weighted Gene Co-expression Network Analysis (WGCNA) were employed to screen key differentially expressed proteins. The role of APOM in myocardial injury was validated using APOM-knockout (KO) mice. Furthermore, nuclear-cytoplasmic fractionation, immunofluorescence, and Western blot were performed to investigate its effects on the Saa1 and NF-κB signaling, NLRP3-related inflammatory signaling pathway, and lipid metabolism pathways. Clinical analysis indicated that stroke is a significant risk factor for MI (OR = 4.5). In the mouse model, MCAO significantly exacerbated post-MI electrocardiographic abnormalities, myocardial inflammatory response, while elevating circulating levels of cTnT and IL-1β. Proteomics identified a significant downregulation of APOM in the heart, brain, and serum post-stroke, a trend consistent with observations in AIS patients. Further experiments revealed that APOM deficiency markedly worsened cardiac conduction disturbances, histological damage, and inflammatory responses in MI mice. Mechanistically, the loss of APOM upregulates the acute-phase protein Saa1, triggers NF-κB phosphorylation and nuclear translocation, and enhances inflammatory signaling related to inflammasomes, while simultaneously mediating cytokine release from cardiomyocytes. Concurrently, APOM deficiency led to a significant decrease in sphingosine-1-phosphate (S1P) and also caused myocardial lipid droplet accumulation and metabolite changes. Additionally, the loss of APOM increased the expression of D-dimer and fibrinogen family proteins. Our findings suggest that APOM is a potential cardioprotective agent post-AIS. Downregulation of APOM may exacerbate myocardial injury after MI by elevating Saa1 expression, activating the NF-κB pathway and the inflammasome-mediated signaling, and inducing lipid metabolic disorders and coagulation-associated alterations. APOM may represent a potential therapeutic target for the intervention of brain-heart syndrome.

Animals↗

PubMed2006

Co-inoculation of DNA and protein vaccines induces antigen-specific T cell suppression.

Immunization can sometimes lead to antigen-specific immune suppression. In this study, we investigated this phenomenon by testing several combinations of DNA and protein vaccines directed against various viruses. We find that co-inoculation of mice with combined DNA and protein vaccines induces immune suppression if the two vaccines are "matched" by targeting the same antigen. Conversely, vaccine combinations never lead to immune suppression if they are derived from different viruses and, thus, mismatched antigenically. We have further identified CD4+CD25- T cells as the type of regulatory T cells induced by and are responsible for suppressing T cell activities in an antigen-specific manner in immunized animals. These regulatory T cells are phenotypically unique in their expression of Foxp3, IL-10, and IFN-gamma. Our study thus shows for the first time that co-administration of antigen-matched DNA and protein vaccines can generate this type of adaptive regulatory T cells.

Animals↗

PubMed2006

Inactivation of PKCtheta leads to increased susceptibility to obesity and dietary insulin resistance in mice.

In this study, we investigated the metabolic phenotype of PKCtheta knockout mice (C57BL/6J) on chow diet and high-fat diet (HFD). The knockout (KO) mice are normal in growth and reproduction. On the chow diet, body weight and food intake were not changed in the KO mice; however, body fat content was increased with a corresponding decrease in body lean mass. Energy expenditure and spontaneous physical activity were decreased in the KO mice. On HFD, energy expenditure and physical activity remained low in the KO mice. The body weight and fat content were increased rapidly in the KO mice. At 8 wk on HFD, severe insulin resistance was detected in the KO mice with hyperinsulinemic euglycemic clamp and insulin tolerance test. Insulin action in both hepatic and peripheral tissues was reduced in the KO mice. Plamsa free fatty acid was increased, and expression of adiponectin in the adipose tissue was decreased, in the KO mice on HFD. This study suggests that loss of PKCtheta reduces energy expenditure and increases the risk of dietary obesity and insulin resistance in mice.

Adiponectin↗

PubMed2006

A systematic review and meta-analysis of the relationship between lipoprotein lipase Asn291Ser variant and diseases.

This systematic review attempted to summarize the associations between the Asn291Ser variant in the lipoprotein lipase (LPL) gene and dyslipidemia, the risk of type 2 diabetes mellitus (T2DM), and coronary heart disease (CHD). In addition, the relationships between the Asn291Ser variant and other metabolic diseases such as obesity and high blood pressure were also investigated in this systematic review. We systematically reviewed the literature by means of a meta-analysis. Twenty-one articles, including 19,246 white subjects, were selected for this meta-analysis. The summary standardized mean difference (SMD) of plasma triglyceride (TG) for carriers compared with noncarriers of the Asn291Ser variant was 3.23 (P < 0.00001). The summary SMD of plasma HDL-cholsterol (HDL-C) for carriers compared with noncarriers of the Asn291Ser variant was -3.42 (P < 0.0001). The summary SMD of the association of the Asn291Ser variant with plasma TG increased with increasing age and weight gain. Significant interactions between the LPL Asn291Ser variant and fasting glucose, T2DM, and CHD were seen (P = 0.02, 0.04, and 0.01, respectively). No significant interactions were seen between the LPL Asn291Ser variant and body mass index, waist-hip ratio, and blood pressure (P > 0.05). This meta-analysis indicates that the Asn291Ser variant in the LPL gene is a risk factor for dyslipidemia, characterized by hypertriglyceridemia and low HDL-C levels. And the Asn291Ser variant in the LPL gene predisposes to more severe dyslipidemia with increasing age and weight gain. Also, this meta-analysis shows that the LPL Asn291Ser variant is associated with CHD and T2DM.

Amino Acid Substitution↗

PubMed2006

Abdominal aortic aneurysm is a specific antigen-driven T cell disease.

To determine whether monoclonal/oligoclonal T cells are present in abdominal aortic aneurysm (AAA) lesions, we amplified beta-chain T cell receptor (TCR) transcripts from these lesions by the nonpalindromic adaptor (NPA)-polymerase chain reaction (PCR)/V-beta-specific PCR followed by cloning and sequencing. Sequence analysis revealed the presence of substantial proportions of identical beta-chain TCR transcripts in AAA lesions in 9 of 10 patients examined, strongly suggesting the presence of oligoclonal populations of alphabeta TCR+ T cells. We have also shown the presence of oligoclonal populations of gammadelta TCR+ T cells in AAA lesions. Sequence analysis after appropriate PCR amplification and cloning revealed the presence of substantial proportions of identical VgammaI and VgammaII TCR transcripts in 15 of 15 patients examined, and of Vdelta1 and Vdelta2 TCR transcripts in 12 of 12 patients. These clonal expansions were very strong. All these clonal expansions were statistically significant by the binomial distribution. In other studies, we determined that mononuclear cells infiltrating AAA lesions express early- (CD69), intermediate- (CD25, CD38), and late- (CD45RO, HLA class II) activation antigens. These findings suggest that active ongoing inflammation is present in the aortic wall of patients with AAA. These results demonstrate that oligoclonal alphabeta TCR+ and gammadelta TCR+T cells are present in AAA lesions. These oligoclonal T cells have been clonally expanded in vivo in response to yet unidentified antigens. Although the antigenic specificity of these T cells remains to be determined, these T cells may play a significant role in the initiation and/or the propagation of the AAA. It appears that AAA is a specific antigen-driven T cell disease.

Antigens↗

PubMed2005

Ca2+ influx-induced sarcoplasmic reticulum Ca2+ overload causes mitochondrial-dependent apoptosis in ventricular myocytes.

Increases in Ca2+ influx through the L-type Ca2+ channel (LTCC, Cav1.2) augment sarcoplasmic reticulum (SR) Ca2+ loading and the amplitude of the cytosolic Ca2+ transient to enhance cardiac myocyte contractility. Our hypothesis is that persistent increases in Ca2+ influx through the LTCC cause apoptosis if the excessive influx results in SR Ca2+ overload. Feline ventricular myocytes (VMs) in primary culture were infected with either an adenovirus (Ad) containing a rat Cav1.2 beta2a subunit-green fluorescent protein (GFP) fusion gene (Adbeta2a) to increase Ca2+ influx or with AdGFP as a control. Significantly fewer beta2a-VMs (21.4+/-5.6%) than GFP-VMs (99.6+/-1.7%) were viable at 96 hours. A fraction of beta2a-VMs (20.8+/-1.8%) contracted spontaneously (SC-beta2a-VMs), and viability was significantly correlated with the percentage of SC-beta2a-VMs. Higher percentages of apoptotic nuclei, DNA laddering, and cytochrome C release were detected in beta2a-VMs. This apoptosis was prevented with pancaspase or caspase-3 or caspase-9 inhibitors. L-type calcium current (I(Ca-L)) density was greater in beta2a-VMs (23.4+/-2.8 pA/pF) than in GFP-VMs (7.6+/-1.6 pA/pF). SC-beta2a-VMs had higher diastolic intracellular Ca2+ (Indo-1 ratio: 1.1+/-0.1 versus 0.7+/-0.03, P<0.05) and systolic Ca2+ transients (1.89+/-0.27 versus 0.80+/-0.08) than GFP-VMs. Inhibitors of Ca2+ influx, SR Ca2+ uptake and release, mitochondrial Ca2+ uptake, mitochondrial permeation transition pore, calpain, and Bcl-2-associated X protein protected beta2a-VMs from apoptosis. These results show that persistent increases in Ca2+ influx through the I(Ca-L) enhance contractility but lead to apoptosis through a mitochondrial death pathway if SR Ca2+ overload is induced.

Animals↗

PubMed2005

The adjuvant effect of levamisole on killed viral vaccines.

To explore adjuvants that are capable of promoting Th1-biased immune response, we investigated the usefulness of levamisole (LMS) as one such adjuvant for two different preparations of killed viral vaccines, derived from the foot mouth disease virus (FMDV) or the porcine respiratory reproductive syndrome virus (PRRSV) and tested respectively in BALB/c or C57 BL/6 mice. The results showed that LMS induced different types of immune responses in the host, depending on its dosage. While a high level of serum IgG was induced by using LMS at 2%, the most robust T cell proliferation was induced with LMS at 0.5%. The Th1 and Th2 cytokine profiles, which tracked well with the antibody and T cell responses, were similarly influenced by the dose of LMS. Moreover, the enhanced T cell response correlated with increased expression of MHC and co-stimulatory molecules and decreased expression of the suppressors of cytokine signaling molecules (SOCS1 and SOCS3) in the spleen, suggesting that it is mediated by the antigen presentation, co-stimulator signaling, and cytokine production pathways. These results establish that LMS can be used to induce Th1-biased immune responses when combined with killed-virus-based antiviral vaccines and that such adjuvant effect depends on the optimal LMS dosage.

Adjuvants, Immunologic↗

PubMed2005

Leptin inhibits apolipoprotein M transcription and secretion in human hepatoma cell line, HepG2 cells.

Apolipoprotein M (apoM) is a novel apolipoprotein presented mostly in high-density lipoprotein (HDL) in human plasma. Previously we have reported that both leptin and leptin receptor are essential for apoM expression in vivo. The expression of apoM is lower in the leptin deficient (ob/ob) mouse and leptin receptor deficient (db/db) mouse than in the normal mouse. In the present study, however, we demonstrated that supra-physiological concentrations of recombinant leptin significantly inhibited apoM transcription and secretion in the human hepatoma cell line, HepG2 cells. Both Northern blotting and real-time RT-PCR were applied into the analyses of apoM mRNA levels, and compatible data were obtained. The inhibitory effect of leptin on apoM mRNA levels in HepG2 cells is dose dependent, i.e. 100 ng/mL of leptin decreased apoM mRNA levels by 30%, and 500 ng/mL of leptin decreased apoM mRNA levels about 50%. Even at a physiological concentration of leptin (10 ng/mL), apoM expression was decreased, and in parallel, the secretion of apoM into the medium was also decreased. Furthermore, we examined apoAI, apoB and apoE by Northern blotting analyses. The results demonstrated that leptin does not significantly influence the expressions of apoAI, apoB and apoE in HepC2 cells, suggesting that leptin has a specific regulatory effect on hepatic apoM transcription and secretion in vitro. The mechanism on the contradictory effects of leptin on apoM expression in vivo and in vitro needs further investigation.

Animals↗

PubMed2004

Apolipoprotein M.

Apolipoprotein M (apoM) is a 26-kDa protein that is mainly associated with high-density lipoprotein (HDL) in human plasma, with a small proportion present in triglyceride-rich lipoproteins (TGRLP) and low-density lipoproteins (LDL). Human apoM gene is located in p21.31 on chromosome 6 (chromosome 17, in mouse). Human apoM cDNA (734 base pairs) encodes 188-amino acid residue-long protein. It belongs to lipocalin protein superfamily. Human tissue expression array study indicates that apoM is only expressed in liver and in kidney and small amounts are found in fetal liver and kidney. In situ apoM mRNA hybridization demonstrates that apoM is exclusively expressed in the hepatocytes and in the tubule epithelial cells in kidney. Expression of apoM could be regulated by platelet activating factor (PAF), transforming growth factors (TGF), insulin-like growth factor (IGF) and leptin in vivo and/or in vitro. It has been demonstrated that apoM expression is dramatically decreased in apoA-I deficient mouse. Hepatocyte nuclear factor-1alpha (HNF-1alpha) is an activator of apoM gene promoter. Deficiency of HNF-1alpha mouse shows lack of apoM expression. Mutations in HNF-1alpha (MODY3) have reduced serum apoM levels. Expression of apoM is significantly decreased in leptin deficient (ob/ob) mouse or leptin receptor deficient (db/db) mouse. ApoM concentration in plasma is positively correlated to leptin level in obese subjects. These may suggest that apoM is related to the initiation and progression of MODY3 and/or obesity.

Journal Article↗

PubMed2004

Inhibition of insulin sensitivity by free fatty acids requires activation of multiple serine kinases in 3T3-L1 adipocytes.

Insulin receptor substrate (IRS) has been suggested as a molecular target of free fatty acids (FFAs) for insulin resistance. However, the signaling pathways by which FFAs lead to the inhibition of IRS function remain to be established. In this study, we explored the FFA-signaling pathway that contributes to serine phosphorylation and degradation of IRS-1 in adipocytes and in dietary obese mice. Linoleic acid, an FFA used in this study, resulted in a reduction in insulin-induced glucose uptake in 3T3-L1 adipocytes. This mimics insulin resistance induced by high-fat diet in C57BL/6J mice. The reduction in glucose uptake is associated with a decrease in IRS-1, but not IRS-2 or GLUT4 protein abundance. Decrease in IRS-1 protein was proceeded by IRS-1 (serine 307) phosphorylation that was catalyzed by serine kinases inhibitor kappaB kinase (IKK) and c-JUN NH2-terminal kinase (JNK). IKK and JNK were activated by linoleic acid and inhibition of the two kinases led to prevention of IRS-1 reduction. We demonstrate that protein kinase C (PKC) theta is expressed in adipocytes. In 3T3-L1 adipocytes and fat tissue, PKCtheta was activated by fatty acids as indicated by its phosphorylation status, and by its protein level, respectively. Activation of PKCtheta contributes to IKK and JNK activation as inhibition of PKCtheta by calphostin C blocked activation of the latter kinases. Inhibition of either PKCtheta or IKK plus JNK by chemical inhibitors resulted in protection of IRS-1 function and insulin sensitivity in 3T3-L1 adipocytes. These data suggest that: 1) activation of PKCtheta contributes to IKK and JNK activation by FFAs; 2) IKK and JNK mediate PKCtheta signals for IRS-1 serine phosphorylation and degradation; and 3) this molecular mechanism may be responsible for insulin resistance associated with hyperlipidemia.

Adipocytes↗

PubMed2003

Primmorphs from archaeocytes-dominant cell population of the sponge hymeniacidon perleve: improved cell proliferation and spiculogenesis.

Marine sponges (Porifera) possess an extraordinary diversity of bioactive metabolites for new drug discovery and development. In vitro cultivation of sponge cells in a bioreactor system is very attractive for the sustainable production of sponge-derived bioactive metabolites; however, it is still a challenging task. The recent establishment of sponge primmorphs, multicellular aggregates from dissociated mixed-cell population (MCP), has been widely acknowledged to hold great promise for cultivation in vitro. Here we present a new method to establish an in vitro sponge primmorph culture from archaeocyte-dominant cell population (ADCP) enriched by a Ficoll gradient, rather than a mixed-cell population (MCP). Our rationale is based upon the totipotency (the ability of a cell to differentiate into other cell types) of archaeocyte cells and the different biological functions of various sponge cell types. A sponge, Hymeniacidon perleve collected from the China Yellow Sea was used as a model system for this investigation. Distinct dynamics of primmorph formation were observed while significant increases in DNA synthesis, cell proliferation (up to threefold), and cell growth (up to fourfold) were achieved. Furthermore, a time-dependent spiculogenesis was clearly demonstrated in our longterm culture, indicating high metabolic activity of primmorphs from the ADCP. This new method represents an important step forward to advance sponge cell culture in vitro that may lead to commercial exploitation of sponge-derived drugs.

Animals↗

PubMed2003

Optimizing the formation of in vitro sponge primmorphs from the Chinese sponge Stylotella agminata (Ridley).

The establishment and optimization of in vitro primmorph formation from a Chinese sponge, Stylotella agminata (Ridley), collected from the South China Sea, were investigated. Our aims were to identify the key factors affecting primmorph formation in this species and to optimize the technique for developing an in vitro primmorph culture system. The size of dissociated cells from S. agminata is relatively small, in the range between 5 and 10 microm. Round-shaped primmorphs of less than 100 microm were formed 3 days after transferring the dissociated cells into seawater containing Ca(2+) and Mg(2+). The effect of various cell dissociation conditions, inoculum cell density, concentration of antibiotics, pH, and temperature was further investigated upon the formation of primmorphs. The time required for primmorph formation, primmorph size distribution, and the proliferating capability were microscopically documented. Healthy sponge S. agminata, inoculum cell density and culture temperature play a critical role for the successful formation of primmorphs and that the microbial contamination will have to be controlled.

Animals↗

PubMed2003

Biopotentials of marine sponges from China oceans: past and future.

An extensive literature survey of over 17 Journals was carried out on Chinese sponges and their natural products in the period from 1980 to 2001. This review is thus intended to provide the first thorough overview of research on marine sponges from China Ocean territories. Information is provided about the rather-limited taxonomic study of Chinese marine sponges, with an analysis on their distribution and diversity. Research findings on the natural products and their bioactivity screening from Chinese sponges are summarized. The weaknesses, gaps and problems in the past R&D program of Chinese sponges are identified, which point to the future opportunities in exploiting these huge untapped sponge resources. The report is expected to serve as an entry point for understanding Chinese sponges and for furthering R&D on their bioactive compounds for new drug development.

Animals↗

PubMed2002

Inhibition of TNF-alpha gene expression and bioactivity by site-specific transcription factor-binding oligonucleotides.

The present study investigated transcriptional inactivation of TNF-alpha gene by nuclear factor-binding oligonucleotides (ON) and their effects on pulmonary inflammatory responses in mice. PCR-based gene mutation and gel shift assays were used to identify specific cis-acting elements necessary for nuclear factor binding and transactivation of TNF-alpha gene by lipopolysaccharide (LPS). LPS inducibility of TNF-alpha was shown to require transcriptional activation by NF-kappaB at multiple binding sites, including the -850 (kappa1), -655 (kappa2), and -510 (kappa3) sites, whereas the -210 (kappa4) site had no effect. Maximum inducibility was associated with the activation of kappa3 site. The sequence-specific, double-stranded ON targeting this site was most effective in inhibiting TNF-alpha activity induced by LPS. The inhibitory effect of ON on TNF-alpha bioactivity was also investigated using a murine lung inflammation model. Pretreatment of mice with ON, but not its mutated sequence, inhibited LPS-induced inflammatory neutrophil influx and TNF-alpha production by lung cells. Effective inhibition by ON in this model was shown to require a liposomal agent for efficient cellular delivery of the ON. Together, our results indicate that transcriptional inactivation of TNF-alpha gene can be achieved by using ON that compete for nuclear factor binding to TNF-alpha gene promoter. This gene inhibition approach may be used as a research tool or as potential therapeutic modality for diseases with etiology dependent on aberrant gene expression.

Animals↗

PubMed2002

Archaeal genome organization and stress responses: implications for the origin and evolution of cellular life.

For DNA to be used as an informational molecule it must exist in the cell on the edge of stability because all genomic processes require local controlled melting. This presents mechanistic opportunities and problems for genomic DNA from hyperthermophilic organisms, whose unpackaged DNA could melt at optimal temperatures for growth. Hyperthermophiles are suggested to employ the novel positively supercoiling topoisomerase enzyme reverse gyrase (RG) to form positively supercoiled DNA that is intrinsically resistant to thermal denaturation. RG is presently the only archaeal gene that is uniquely found in hyperthermophiles and therefore is central to hypotheses suggesting a hypothermophilic origin of life. However, the suggestion that RG has evolved by the fusion of two pre-existing enzymes has led to hypotheses for a lower temperature for the origin of life. In addition to the action of topoisomerases, DNA packaging and the intracellular ionic environment can also manipulate DNA topology significantly. In the Euryarchaeota, nucleosomes containing minimal histones can adopt two alternate DNA topologies in a salt-dependent manner. From this we hypothesize that since internal salt concentrations are increased following an increase in temperature, the genomic effects of temperature fluctuations could also be accommodated by changes in nucleosome organization. In addition, stress-induced changes in the nucleoid proteins could also play a role in maintaining the genome in the optimal topological state in changing environments. The function of these systems could therefore be central to temperature adaptation and thus be implicated in origin of life scenarios involving hyperthermophiles.

Archaea↗

PubMedDate not supplied

Application of a MTT assay for screening nutritional factors in growth media of primary sponge cell culture.

Marine sponges (Porifera) are producers of the largest variety of bioactive compounds among benthic marine organisms. In vitro culture of marine sponge cells has been proposed for the sustainable production of these pharmacologically interesting compounds from marine sponges but with limited success. The development of a suitable growth medium is an essential prerequisite for sponge cells grown in vitro. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was adapted to screen for potential nutritional factors in formulating a growth medium for primary cell culture of Suberites domuncula. In 96-well plates, the effects of nutritional factors including glutamine, pyruvate, iron citrate, silicon, RPMI 1640, and Marine Broth 2216 on the viable cell density were examined in primary cell culture of S. domuncula 36 h after inoculation. Ferric iron (Fe(3+)) and pyruvate were found to significantly improve cell viability in a dose-dependent manner. Silicon and glutamine showed limited improvements at certain concentrations. The supplement of RPMI 1640 and Marine Broth 2216 did not increase cell viability. As a result, several improved media able to maintain higher cell viability in a short-term culture of primary sponge cells could be formulated.

Animals↗