Biomedical subjects

Q Gong

Publications and source records attributed to Q Gong.

At least 19 recordsLinked to original sources

PubMed2005

Streptozotocin (STZ) mediates acute upregulation of serum and pancreatic osteopontin (OPN): a novel islet-protective effect of OPN through inhibition of STZ-induced nitric oxide production.

Osteopontin (OPN) is a secreted acidic phosphoprotein that binds to a cell-surface integrin-binding motif and is involved in many inflammatory and immune-modulating disorders. There is compelling evidence that soluble OPN can in a variety of situations help cells survive an otherwise lethal insult. In this study we show that OPN is localized in the rat pancreatic islets and ducts. Staining of pancreatic serial sections with islet hormone antibodies showed that all islet cells express OPN. Rats treated with a single dose of streptozotocin (STZ; 50 mg/kg) showed acute upregulation of serum OPN levels and pancreatic OPN mRNA and protein. Serum OPN dropped by the end of day 7 but was still higher than prediabetic levels. Pancreatic mRNA and protein showed a similar pattern. Twenty-four hours after STZ injection, the intensified OPN expression was localized towards the periphery of the islets and surrounded the remaining insulin-positive cells. To explore the significance of OPN acute upregulation, freshly isolated islets were pretreated with OPN (0.15-15 nM) before addition of STZ. OPN significantly reduced the STZ-induced NO levels in the islets through an Arg-Gly-Asp (RGD)-dependent reduction of inducible NO synthase (iNOS) mRNA levels. Addition of OPN to freshly isolated mildly diabetic islets (blood glucose <300 mg/dl) significantly improved their glucose-stimulated insulin secretion and reduced their NO levels. Next we investigated the regulation of OPN in beta-cells. When STZ (5 mM) was added to the beta-cell line RINm5F it significantly increased OPN mRNA levels within 6 h. To distinguish between the effect of STZ and high glucose on OPN transcription, RINm5F cells were transfected with luciferase-labeled rat OPN promoter and treated with STZ (0.05-5 mM) or with glucose (5-25 mM). STZ induced upregulation of OPN promoter activity within 3 h, while high glucose induced upregulation of OPN promoter activity after 48 h. Our data introduce OPN as a novel islet protein that is differentially regulated by STZ and glucose in the islets. OPN initial upregulation after diabetes induction was probably due to STZ-induced toxicity, while maintenance of the high OPN levels might be due to hyperglycemia. The acute induction of OPN after STZ-induced diabetes might represent an endogenous mechanism to protect the islets against STZ-induced cytotoxicity, partly via an RGD-dependent NO regulatory mechanism.

Alkylating Agents↗

PubMed2004

Activation of fibronectin gene expression by hepatitis B virus x antigen.

The development of fibrosis and cirrhosis during chronic hepatitis B virus (HBV) infection correlates with the persistent expression of HBV x antigen (HBxAg), which acts in part, by stimulating selected signal transduction pathways, including nuclear factor kappa B (NF-kappa B). To identify NF-kappa B responsive genes that are differentially expressed in HBxAg-positive cells, HepG2 cells were stably transfected with HBxAg, and then with pZeoSV2 or pZeoSV2-I kappa B alpha. When RNAs from each culture were compared by PCR-select cDNA subtraction, fibronectin (FN) mRNA was shown to be strongly down-regulated by I kappa B alpha. Up-regulated expression of FN and co-expression between FN and HBxAg were observed in liver sections from HBV carriers that were stained for HBxAg and analysed for FN mRNA by in situ hybridization (ISH). In liver cell cultures, HBxAg increased the levels of FN mRNA and protein. This was because of the HBxAg-mediated trans-activation of the FN promoter, which was NF-kappa B-dependent. HBxAg also antagonized the repression of the FN promoter by the tumour suppressor, p53. Hence, the FN gene may be a natural target for HBxAg trans-activation, perhaps through activation of NF-kappa B and inactivation of p53, thereby contributing to the accumulation of FN in the liver over the course of chronic HBV infection.

Cell Line↗

PubMed2003

Principal component regression analysis with SPSS.

The paper introduces all indices of multicollinearity diagnoses, the basic principle of principal component regression and determination of 'best' equation method. The paper uses an example to describe how to do principal component regression analysis with SPSS 10.0: including all calculating processes of the principal component regression and all operations of linear regression, factor analysis, descriptives, compute variable and bivariate correlations procedures in SPSS 10.0. The principal component regression analysis can be used to overcome disturbance of the multicollinearity. The simplified, speeded up and accurate statistical effect is reached through the principal component regression analysis with SPSS.

Regression Analysis↗

PubMed2002

Differential involvement of the hippocampus and temporal lobe cortices in rapid and slow learning of new semantic information.

The present study examined the rapid and slow acquisition of new semantic information by two patients with differing brain pathology. A partial double dissociation was found between the patterns of new learning shown by these two patients. Rapid acquisition was impaired in a patient (YR) who had relatively selective hippocampal damage, but it was unimpaired in another patient (JL) who, according to structural MRI, had an intact hippocampus but damage to anterolateral temporal cortex accompanied by epileptic seizures. Slow acquisition was impaired in both patients, but was impaired to a much greater extent in JL. The dissociation suggests that the mechanisms underlying rapid and slow acquisition of new semantic information are at least partially separable. The findings indicate that rapid acquisition of semantic, as well as episodic information, is critically dependent on the hippocampus. However, they suggest that hippocampal processing is less important for the gradual acquisition of semantic information through repeated exposure, although it is probably necessary for normal levels of such learning to be achieved.

Adult↗

PubMed2002

Cross-hybridization of closely related genes on high-density macroarrays.

DNA macroarrays are used in many areas of molecular biology research for applications ranging from gene discovery to gene expression profiling. As an increasing number of specialized macroarrays containing genes related by function or pathway are becoming available, a question that needs to be addressed is the level of hybridization signal specificity between highly similar genes that can be achieved. We have examined the ability of our LifeGrid macroarrays to distinguish hybridization signals between closely related genes. We determined the level of cross-hybridization among genes ranging from 52% to 94% sequence identity. Fragments of genes fromfive protein families were arrayed onto nylonfilters. Thefilters were subsequently hybridized with a 33P-labeled probe prepared from a pool of synthetic mRNA transcripts containing a representative of each protein family. We found that fragments containing sequences with up to 94% sequence identity displayed relatively little cross-hybridization. We conclude that this macroarray system is very specific and that hybridization signals from closely related genes can be reliably measured.

Cloning, Molecular↗

PubMed2001

Tomato yellow leaf curl China virus: monopartite genome organization and agroinfection of plants.

The complete DNA sequence (2734 nucleotides) of the monopartite genome of tomato yellow leaf curl China virus (TYLCCNV), a begomovirus transmitted by the whitefly Bemisia tabaci, was determined. The circular genomic DNA contains six open reading frames (ORFs) encoding proteins of molecular weights >10 kDa, of which two (V1 and V2) are located on the virion-sense strand and four (C1, C2, C3 and C4) on the complementary-sense strand. The ORFs are comparable to those of other whitefly-transmitted begomoviruses with a monopartite genome and to those encoded by DNA-A of bipartite begomoviruses. Sequence comparisons with other geminiviruses showed that TYLCCNV belongs to Begomovirus from the Old World. No putative DNA-B genome was found. Nicotiana species and tomato plants agroinoculated with the TYLCCNV monopartite genome developed typical yellowing and leaf-curling symptoms. The cloned molecule carried all the information needed for virus replication and systemic infection of plants.

China↗

PubMed2001

Friend of GATA-1 represses GATA-3-dependent activity in CD4+ T cells.

The development of naive CD4+ T cells into a T helper (Th) 2 subset capable of producing interleukin (IL)-4, IL-5, and IL-13 involves a signal transducer and activator of transcription (Stat)6-dependent induction of GATA-3 expression, followed by Stat6-independent GATA-3 autoactivation. The friend of GATA (FOG)-1 protein regulates GATA transcription factor activity in several stages of hematopoietic development including erythrocyte and megakaryocyte differentiation, but whether FOG-1 regulates GATA-3 in T cells is uncertain. We show that FOG-1 can repress GATA-3-dependent activation of the IL-5 promoter in T cells. Also, FOG-1 overexpression during primary activation of naive T cells inhibited Th2 development in CD4+ T cells. FOG-1 fully repressed GATA-3-dependent Th2 development and GATA-3 autoactivation, but not Stat6-dependent induction of GATA-3. FOG-1 overexpression repressed development of Th2 cells from naive T cells, but did not reverse the phenotype of fully committed Th2 cells. Thus, FOG-1 may be one factor capable of regulating the Th2 development.

Animals↗

PubMed2001

Requirement for tyrosine residues 315 and 319 within zeta chain-associated protein 70 for T cell development.

Engagement of the T cell antigen receptor (TCR) induces the transphosphorylation of the zeta chain-associated protein of 70,000 Mr (ZAP-70) protein tyrosine kinase (PTK) by the CD4/8 coreceptor associated Lck PTK. Phosphorylation of Tyr 493 within ZAP-70's activation loop results in the enzymatic activation of ZAP-70. Additional tyrosines (Tyrs) within ZAP-70 are phosphorylated that play both positive and negative regulatory roles in TCR function. Phosphorylation of Tyr residues (Tyrs 315 and 319) within the Interdomain B region of the ZAP-70 PTK plays important roles in the generation of second messengers after TCR engagement. Here, we demonstrate that phosphorylation of these two Tyr residues also play important roles in mediating the positive and negative selection of T cells in the thymus.

Animals↗

PubMed2001

Measurement of the bioactivity of interleukin and tumour necrosis factor in synovial fluid of Kashin-Beck disease.

We studied the bioactivity of interleukin (IL-1) and tumour necrosis factor (TNF) in the synovial fluid of 12 patients with Kashin-Beck disease (KBD), 8 patients with osteoarthritis (OA) and 8 normal controls. C57 female mouse T cell proliferation method was used to test the bioactivity of IL-1, and lethality method with L929 cells to test the bioactivity of TNF. The bioactivities of IL-1 and TNF in the synovial fluid from patients with KBD were higher than those in the synovial fluid of osteoarthritis and normal controls, indicating the participation of IL-1 and TNF in the pathogenesis of KBD.

Adult↗

PubMed2001

Disruption of T cell signaling networks and development by Grb2 haploid insufficiency.

The developmental processes of positive and negative selection in the thymus shape the T cell antigen receptor (TCR) repertoire and require the integration of multiple signaling networks. These networks involve the efficient assembly of macromolecular complexes and are mediated by multimodular adaptor proteins that permit the functional integration of distinct signaling molecules. We show here that decreased expression of the adaptor protein Grb2 in Grb2+/- mice weakens TCR-induced c-Jun N-terminal kinase (JNK) and p38, but not extracellular signal-regulated kinase (ERK), activation. In turn, this selective effect decreases the ability of thymocytes to undergo negative, but not positive, selection. We also show that there are differences in the signaling thresholds of the three mitogen-activated protein kinase (MAPK) families. These differences may provide a mechanism by which quantitative differences in signal strength can alter the balance of downstream signaling pathways to induce the qualitatively distinct biological outcomes of proliferation, differentiation or apoptosis.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Cocaine blocks HERG, but not KvLQT1+minK, potassium channels.

Cocaine causes cardiac arrhythmias, sudden death, and occasionally long QT syndrome in humans. We investigated the effect of cocaine on the human K(+) channels HERG and KvLQT1+minK that encode native rapidly (I(Kr)) and slowly (I(Ks)) activating delayed rectifier K(+) channels in the heart. HERG and KvLQT1+minK channels were heterologously expressed in human embryonic kidney 293 cells, and whole-cell currents were recorded. Cocaine had no effect on KvLQT1+minK current in concentrations up to 200 microM. In contrast, cocaine reversibly blocked HERG current with half-maximal block of peak tail current of 7.2 microM. By using a protocol to quickly activate HERG channels, we found that cocaine block developed rapidly after channel activation. At 0 mV, the time constants for the development of block were 38.2 +/- 2.1, 15.2 +/- 0.8, and 6.9 +/- 1.1 ms in 10, 50 and 200 microM cocaine, respectively. Cocaine-blocked channels also recovered rapidly from block after repolarization. At -100 mV, recovery from block followed a biphasic time course with fast and slow time constants of 3.5 +/- 0.7 and 100.3 +/- 15.4 ms, respectively. Using N-methyl-cocaine, a permanently charged, membrane-impermeable cocaine analog, block of HERG channels rapidly developed when the drug was applied intracellularly through the patch pipette, suggesting that the cocaine binding site on the HERG protein is located on a cytoplasmic accessible domain. These results indicate that cocaine suppresses HERG, but not KvLQT1+minK, channels by preferentially blocking activated channels, that it unblocks upon repolarization, and does so with unique ultrarapid kinetics. Because the cocaine concentration range we studied is achieved in humans, HERG block may provide an additional mechanism for cocaine-induced arrhythmias and sudden death.

Cation Transport Proteins↗

PubMed2001

[Use of intraoperative red blood cell salvage in the anterior stabile operation of spinal fracture].

OBJECTIVE: To observe the clinical results in the anterior stabile operation of spinal fracture using red blood salvage. METHODS: Nineteen cases with spinal fracture were performed the anterior decompress operation. Blood cell salvage were used during operation. Other 20 cases were also reviewed as control group, who were received the same operation without blood cell salvage. RESULTS: In the 19 cases, average volume of autologous transfusion was 536 ml. Only two cases had homologous transfusion requirements. In the control group, all cases needed homologous transfusion (averaged 947 ml). CONCLUSION: In the anterior decompress operation, the intraoperative blood salvage is highly effective in reducing transfusion and also improves the security of operation.

Adolescent↗

PubMed2001

[Inquiries about methods of primary eye care and prevention of blindness].

OBJECTIVE: To inquire about the methods of developing primary eye care (PEC) and prevention of blindness. METHODS: The methods of developing PEC and prevention of blindness in recent 10 years were analyzed retrospectively. RESULTS: Five grades of PEC network were established. The training courses 1 007 times were held in Nantong, and the epidemiological survey of the blind was carried out for 6 817 259 people. The blind persons were 13 496 in number, and the prevalence of blindness was 0.20%. Cataract operations were performed on 83.16% of the treatable cataract blind persons. The successful rate of cataract surgery was 98.22%. Eight counties became the national advanced counties of prevention of blindness. Nantong city became the first national advanced city of prevention of blindness in 1997. CONCLUSIONS: PEC is the basis of prevention of blindness. To bring PEC into line with the primary health care (PHC) is the key point of developing PEC. Affordable operation, promising quality of the operative procedure and combination of survey and treatment are the three essential factors of developing PEC and prevention of blindness. To create national advanced county and city is the motive force of developing prevention of blindness.

Adult↗

PubMed2001

[Study on relationship between the reflux laryngitis and gastroesophageal reflux disease].

OBJECTIVE: To investigate the relationship between reflux laryngitis and gastroesophageal reflux disease (GRED). METHOD: 130 Patients of refractory chronic laryngitis with upper endoscopy and ambulatory 24-hr esophageal pH-metry. The patients of gastroesophageal reflux disease were divided into two groups. Group A was treated with antacids and motile medications. Group B was control. RESULT: 45 (34.6%) gastroesophageal reflux disease were found in 130 cases. 21 cases(91.3%) were healed in group A. 3 of 22 cases (13.6%) were healed in control (P < 0.01). CONCLUSION: The gastroesophageal reflux disease was an important cause of the reflux laryngitis which symptoms and signs can be healed by antacids and motile medications.

Adult↗

PubMed2001

[Determination of ofloxacin in urine by synchronous-derivative fluorimetry].

The internal hormones in human urine emit strong fluorescence and interfere with the determination of trace ofloxacin. However, the experiments indicate that synchronous-first order derivative fluorimetry can be applied to the determination of trace ofloxacin without interference. The linear range is 0.36-3.6 micrograms.mL-1, detection limit is 0.3 microgram.mL-1, RSD is less than 2.5% and the recovery is within the range of 101%-103%.

Humans↗

PubMed2000

Functional analysis of two promoters for the human mitochondrial glycerol phosphate dehydrogenase gene.

Mitochondrial glycerol phosphate dehydrogenase (mGPD) is abundant in the normal pancreatic insulin cell, but its level is lowered 50% by diabetes. To evaluate mGPD expression, we cloned and characterized the 5'-flanking region of the human mGPD gene. The gene has two alternative first exons and two promoters. The downstream promoter (B) is 10 times more active than the upstream promoter (A) in insulin-secreting cells (INS-1) and HeLa cells. Promoter B has higher activity in INS-1 than in non-beta cells. Deletion and mutation analysis suggested that a NRF-2 binding site at -94 to -101 and an E2F binding site at -208 to -215 are important regulatory cis elements in promoter B. Gel mobility shift assays indicated that the -94 to -101 region binds the NRF-2 protein. When INS-1 cells were maintained in the presence of high glucose (25 mm) for 7 days, mGPD was the only 1 of 6 enzyme activities lowered (53%). mGPD promoter B activity was reduced by 60% in INS-1 cells by the high glucose, but in HepG2 cells and HeLa cells, promoter B activity was unchanged or slightly increased. Deletion analysis indicated the glucose responsiveness was distributed across the region from -340 to -260 in promoter B. The results indicate that mGPD gene transcription in the beta cell is regulated differently from other cells and that decreased mGPD promoter B transcription is at least in part the cause of the decreased beta cell mGPD levels in diabetes.

Base Sequence↗

PubMed2000

Long QT syndrome: cellular basis and arrhythmia mechanism in LQT2.

LQT2 is one form of the congenital long QT syndrome. It results from mutations in the human ether-a-go-go-related gene (HERG), and more than 80 mutations, usually causing single amino acid substitutions in the HERG protein, are known. HERG encodes the ion channel pore-forming subunit protein for the rapidly activating delayed rectifier K+ channel (I(Kr)) in the heart. This review summarizes current findings about mutations causing LQT2, the mechanisms by which mutations may cause the clinical phenotype of a reduction in I(Kr) and a prolonged QT interval, and how this may be involved in the generation of ventricular arrhythmias.

Amino Acid Substitution↗

PubMed2000

P2Y-purinoceptor mediated inhibition of L-type Ca2+ channels in rat pancreatic beta-cells.

We used the patch-clamp technique to study the effects of extracellular ATP on the activity of ion channels recorded in rat pancreatic beta-cells. In cell-attached membrane patches, action currents induced by 8.3 mM glucose were inhibited by 0.1 mM ATP, 0.1 mM ADP or 15 microM ADPbetaS but not by 0.1 mM AMP or 0.1 mM adenosine. In perforated membrane patches, action potentials were measured in current clamp, induced by 8.3 mM glucose, and were also inhibited by 0.1 mM ATP with a modest hyperpolarization to -43 mV. In whole-cell clamp experiments, ATP dose-dependently decreased the amplitudes of L-type Ca2+ channel currents (ICa) to 56.7+/-4.0% (p<0.001) of the control, but did not influence ATP-sensitive K+ channel currents observed in the presence of 0.1 mM ATP and 0.1 mM ADP in the pipette. Agonists of P2Y purinoceptors, 2-methylthio ATP (0.1 mM) or ADPbetaS (15 microM) mimicked the inhibitory effect of ATP on ICa, but PPADS (0.1 mM) and suramin (0.2 mM), antagonists of P2 purinoceptors, counteracted this effect. When we used 0.1 mM GTPgammaS in the pipette solution, ATP irreversibly reduced ICa to 58.4+/-6.6% of the control (p<0.001). In contrast, no inhibitory effect of ATP was observed when 0.2 mM GDPbetaS was used in the pipette solution. The use of either 20 mM BAPTA instead of 10 mM EGTA, or 0.1 mM compound 48/80, a blocker of phospholipase C (PLC), in the pipette solution abolished the inhibitory effect of ATP on ICa, but 1 microM staurosporine, a blocker of protein kinase C (PKC), did not. When the beta-cells were pretreated with 0.4 microM thapsigargin, an inhibitor of the endoplasmic reticulum (ER) Ca2+ pump, ATP lost the inhibitory effect on ICa. These results suggest that extracellular ATP inhibits action potentials by Ca2+-induced ICa inhibition in which an increase in cytosolic Ca2+ released from thapsigargin-sensitive store sites was brought about by a P2Y purinoceptor-coupled G-protein, PI-PLC and IP3 pathway.

Action Potentials↗