Biomedical subjects

H Tang

Publications and source records attributed to H Tang.

At least 73 records · Page 4Linked to original sources

PubMed2001

[An experimental study on the change in cardiac sympathetic neuroelectrophysiology in severely scalded rats during early postburn stage].

OBJECTIVE: To investigate the mechanism and the rule of the change in cardiac sympathetic neuroelectrophysiology in severely scalded rats during early postburn stage, so as to explore the relationship between the change and postburn severe cardiac injury. METHODS: Forty-four Sprague-Dawley rats were randomly divided into normal (n = 6), sham injury (n = 8) and scalded (n = 20) groups. The rats in scalded group were inflicted by 30% TBSA III degree burn on the backs. The electric discharge activity of cardiac sympathetic nerve was observed and recorded by neuroelectrophysiological technique. The changes in ECG and myocardial mechanic indices were simultaneously observed. RESULTS: The activity of efferent cardiac sympathetic nerve increased immediately after scalding, but that of the afferent nerve increased obviously after about 90s incubation period. The activity of efferent nerve further increased after the increase of afferent activity, and this increase in both efferent and afferent nerves lasted for about 3 hours and decreased evidently thereafter. The change of afferent nerve was earlier than that of efferent nerve. The average electric discharge activity of cardiac sympathetic nerve increased with obvious fluctuation, which exhibited intermittent burst pattern at 1 PBH in some rats, in which frequent ventricular extrasystole appeared accompanying with the simultaneous increase in electric discharge burst in 4 rats. The postburn LVDP and +/- dp/dtmax in rats decreased significantly. CONCLUSION: The activities of both efferent and afferent cardiac sympathetic nerve increased dramatically in the early postburn stage. The change in efferent nerve activity could be affected to some degree by that of afferent nerve. This implied that the increase of the neuroelectrophysiological activity of cardiac sympathetic nerve might be one of the causes of early severe postburn cardiac injury.

Animals↗

PubMed2001

[A study on the myocardial contractile function and intracellular free calcium in scalded rats].

OBJECTIVE: To explore the relationship between postburn myocardial function and intracellular free calcium concentration. METHODS: Sprague-Dawley (SD) rats were employed as the model in which 7 were inflicted with 43% TBSA degree scalding (S group) and 7 as sham scalding control group (C group). The hearts of the injured rats were isolated and perfused in vitro by Langendorff method after 24 postburn hours (PBHs). The hearts were connected to a cardiac function monitor, and the dynamic changes in left ventricular develop pressure (LVDP) were continuously monitored. The cardiac 19F and 31P NMR spectroscopy was determined before and after and TF-BAPTA was added to the perfusate. RESULTS: When compared with those in C group, the LVDP of scalded rat heart decreased by 40% (P < 0.01), and the myocardial cytoplasmic free calcium concentration was four times above that in C group (P < 0.01). After TF-BAPTA was taken by myocytes, cardiac LVDP only decreased by 15% to 20%, and the PCr/Pi ratio decreased, while there was no change in ATP. CONCLUSION: Myocardial contractile function could be inhibited after burn injury, which might be related to the increase of myocardial cytoplasmic free calcium concentration.

Animals↗

PubMed2001

[Evaluating wall motion of dilated cardiomyopathy by pulsed-wave Doppler tissue imaging].

OBJECTIVE: To evaluate the characteristics of wall motion in cases of dilated cardiomyopathy (DCM) by the use of Doppler tissue imaging (DTI). METHODS: We observed 30 DCM patients and 30 normal volunteers. For the assessment of short axis motion, the myocardial velocities (MV) and transmural myocardial velocity gradients (MVG) of the middle segments of anterior interventricular septum and left ventricular posterior wall were recorded through parasternal long axis view. We detected the MV of the middle segments of left ventricular walls to evaluate the long axis motion through apical windows(4-chamber, 2-chamber and long axis). RESULTS: Four kinds of abnormal presentations of the waves were seen in DCM cases. The patients' MV of were obviously lower as compared with the controls', especially in long axis; the patients' MVG also decreased significantly (P < 0.05). In the patient group, the heterogeneity of wall motion disappeared too. CONCLUSION: PW-DTI can quantitatively assess the above abnormalities of DCM and provide supplementary information for clinical use.

Adolescent↗

PubMed2001

[Construction of recombinant plasmids containing genes of HBsAg and their expression in the eukaryotic cells].

OBJECTIVE: To construct recombinant plasmids expressing L, M, S and pre-S1-S protein of HBsAg. METHODS: Amplifying segments of S, pre-S2-S, pre-S1-pre-S2-S genes of HBV by PCR and amplifying segment of pre-S1-S by overlap extension PCR; inserting the segments into Rc/CMV and pSG5UTPL/Flag plasmids respectively and exploring their expressions by Western-Blot hybridization, identifying the inserting segments by sequencing. RESULTS: The sequences of the inserted segments were the same as the genes of S, pre-S2-S, pre-S1-pre-S2-S and pre-S1-S and the results of Western-Blot hybridization were positive for the aimed proteins. CONCLUSION: We have gained 8 recombinant plasmids expressing S, M, L and pre-S1-S proteins with high efficacy.

Base Sequence↗

PubMed2001

Hepatitis B virus transcription and replication.

Hepatitis B virus (HBV) replicates by the reverse transcription of the 3.5-kb viral pregenomic RNA. Therefore, the regulation of the transcription of the pregenomic RNA is a critical step in the viral life cycle. Various ubiquitous and liver-enriched transcription factors have been shown to modulate the level of RNA synthesis from the core promoter. The nuclear hormone receptors HNF4 and RXRalpha plus PPARalpha appear to have a critical role in governing pregenomic RNA synthesis from the core promoter in cell culture and probably represent a major determinant governing the hepatotropism of this virus. The level of 3.5-kb HBV RNA synthesis is approximately proportional to the level of viral replication in cell culture; however, this is not the case in the liver of HBV transgenic mice. Directly modulating the levels or activities of specific transcription factors known to regulate HBV transcription in cell culture can increase viral replication in HBV transgenic mice without greatly changing the levels of HBV transcripts. Various immune stimuli that alter transcription factor activities involved in regulating viral RNA synthesis can negatively affect viral replication without affecting HBV transcription. These observations suggest that in vivo very subtle changes in HBV transcription may contribute to large alterations, either negative or positive, in viral replication. Investigation of transcription factor-null HBV transgenic mice under various physiological conditions will be required to establish the putative role of specific transcription factors in regulating viral replication in vivo.

Journal Article↗

PubMed2001

[Expression of hepatitis E virus ORF3 gene fragment in baculovirus system and its immunological character].

OBJECTIVE: To express hepatitis E virus (HEV) ORF3 protein by baculovirus system and provide basis for immunological character research. METHODS: Hepatitis E Virus ORF3 gene fragment was obtained by RT-PCR, ligated with vector pThioHisA for sequencing and then inserted into transfected vector pVL1393 to construct recombinant plasmid. Mediated by Lipofectin Reagent, the recombinant vector and baculovirus linearized DNA (BaculoGold) co-transfected insect cell Sf9 to make recombinant baculovirus. Expressed ORF3 was analyzed for its immunological character by Western blotting, and immunized Kunming Mice. RESULTS: Recombinant ORF3 protein could be recognized by the known positive serum and promoted organism to produce HEV-specific antibody. CONCLUSIONS: Recombinant baculovirus can express effectively HEV ORF3, which has HEV specific immunogenic character.

Animals↗

PubMed2001

[Purification and immunological characterization of hepatitis E virus recombinant chimeric antigen encoded by ORF2 fragments and ORF3].

OBJECTIVE: To study immunological characteristics of recombinant chimeric HEV antigen. METHODS: Constructed recombinant plasmids pThioHisORF(2.1 + 2.2 + 3), which contains three HEV antigen gene fragments (ORF2.1:6287-6403nt, ORF2.2:6743-7126nt, ORF3), was transformed into E. coli and induced with IPTG. Expressed product P(2.1 + 2.2 + 3) existed in inclusion bodies, was purified by denature SP Sepharose FF cation exchange chromatography. Rabbits and rats were immunized with renatured P(2.1 + 2.2 + 3). The level of IgG in sera from experimental animals and clinical patients were examined with P(2.1 + 2.2 + 3) by ELISA. The characteristics of IgG of immunized animals interacted with recombinant antigen expressed by baculovirus system as well as recombinant chimeric antigen interacted with clinical patients sera were evaluated by Western-blotting. RESULTS: High titer of IgG antibodies, 1:25,600 in rabbits and 1:12,800 in rats, were detected after immunized with P(2.1 + 2.2 + 3). Furthermore, recombinant antigen expressed by baculovirus system was specifically recognized by IgG of experimental animal immunized with P(2.1 + 2.2 + 3), and the purified recombinant chimeric antigen P(2.1 + 2.2 + 3) was specifically reacted with the IgG of clinical patients. CONCLUSIONS: Recombinant chimeric antigen appears a promising strategy for detection of and prevention from HEV infection.

Animals↗

PubMed2000

Determination of PyPuPu (PyPuPy) intermolecular triple-stranded DNA by capillary electrophoresis.

The PyPuPu and PyPuPy intermolecular triple-stranded DNA (tsDNA) can be determined more easily by capillary electrophoresis (CE) than by traditional methods. The tsDNA and its component compounds can be well separated by using a sieving matrix of 1.0% hydroxypropylmethylcellulose (HPMC) containing 2.5 mM magnesium ions. Such factors as buffer pH, the concentration of triplex-forming oligonucleotide (TFO), temperature, and the concentration of magnesium cation in the formation and stabilization of triple-stranded helices have been studied with capillary electrophoresis. The triplex cannot be formed when the buffer pH is lower than 4.0. When the concentration of TFO is four times higher than that of dsDNA, all of the dsDNA molecules can be associated. The limit of capillary electrophoresis detection with good reproducibility is 0.5-1 nM (S/N = 3). The CE analysis of short tsDNA takes only 40 min, whereas gel electrophoresis needs at least 5 h.

Antineoplastic Agents↗

PubMed2000

[Repair of cardiac defects by minimal incision without aortic cross-clamp].

From July 1998 to June 1999, seventy two patients underwent repair of congenital heart defects by a partial sternal split and a limited skin incision(4-8 cm) under cardiopulmonary bypass without aortic cross-clamp at our institution. The average age of these patients was 4 years and 5 months(range: 7 months to 12 years), and the average weight was 15.6 kg(range: 7 kg to 30 kg). Fifty six patients had simple ventricular septal defects, sixteen suffered from atrial septal defects. The average bypass time was (21 +/- 20) min (range: 8-58 min). All patients recovered rapidly from the operation in an uneventful postoperative course. Our experience demonstrates that this technique is feasible and can be performed easily in young children with simple cardiac defects, and has excellent cosmetic results.

Cardiopulmonary Bypass↗

PubMed2000

Specific interaction between RNA helicase A and Tap, two cellular proteins that bind to the constitutive transport element of type D retrovirus.

Constitutive transport element (CTE) facilitates retroviral RNA export by interacting with the cellular RNA export machinery. Two cellular proteins, RNA helicase A (RHA) and Tip-associated protein (Tap) were identified as binding to CTE and were proposed to function as CTE co-factors (1,2). Here, we report that these two CTE-binding proteins interact with each other in vitro and in vivo. The in vitro binding of RHA to Tap is direct and independent of either CTE or the nuclear transport domain of RHA. The removal of the first 60 amino acids of Tap significantly diminishes the binding to RHA. The activity of this Tap mutant to enhance CTE-mediated gene expression is also markedly reduced. A transdominant mutant of Tap inhibited RHA-mediated up-regulation of CTE function in mammalian cells. The nuclear transport domain of RHA also interfered with Tap-mediated transactivation of the CTE function in quail cells, in which the function of CTE is dependent on the expression of a functional human Tap cDNA.

Animals↗

PubMed2000

Stability considerations associated with the meniscoid particle band at advancing interfaces in hele-shaw suspension flows

In the free surface flow of dense suspensions in confined domains, spontaneous particle enrichment occurs in the region adjacent to the free surface with an attendant increase in the effective viscosity. We present experimental evidence that this particle accretion introduces stability considerations that would otherwise not exist if the suspension remained uniform. For conditions favoring global stability, a local fingering instability can occur in the accretion band. For conditions favoring global instability, accretion can suppress the global growth of viscous fingers at the interface.

Journal Article↗

PubMed2000

Sam68, RNA helicase A and Tap cooperate in the post-transcriptional regulation of human immunodeficiency virus and type D retroviral mRNA.

Unlike cellular mRNA, retroviral mRNA bypasses the tight coupling of the splicing and nuclear export steps to allow the export of intron-containing viral RNA transcripts to the cytoplasm. Two distinct nuclear export pathways for retroviral mRNA have been described: a CRM-1 dependent pathway mediated by the HIV-1 Rev protein and the Rev Response Element (RRE), and a CRM-1 independent pathway mediated by the Constitutive Transport Element (CTE) of type D retroviruses. Two CTE-binding proteins, RNA helicase A (RHA) and Tap, have been implicated in the nuclear export of CTE-containing RNA. Recently, we reported that expression of RRE-containing RNA could also be mediated by a cellular protein, Sam68, independently of Rev. Here we report evidence that Sam68, RHA and Tap cooperate in the nuclear export of both CTE- and RRE-containing RNA. RHA binds to Sam68 and to Tap both in vivo and in vitro. Over-expression of Sam68 activates both RRE- and CTE-regulated reporter gene expression in human cells and in quail cells in the presence of human Tap. This activation was competitively inhibited by the nuclear transport domain (NTD) of RHA and a transdominant negative mutant of Tap. Conversely, the activation of CTE by Tap in quail cells was inhibited by a transdominant mutant of Sam68 and NTD. We propose that both HIV and type D retroviruses may access the same constitutive RNA nuclear export pathway involving RHA, Tap and Sam68, even though HIV also utilizes the Rev protein for more efficient nuclear export. it is likely that this constitutive export pathway is also used by cellular mRNA, but at a different interface with the splicing process.

Adaptor Proteins, Signal Transducing↗

PubMed2000

A novel shuttle protein binds to RNA helicase A and activates the retroviral constitutive transport element.

The constitutive transport element (CTE) of type D retroviruses mediates the nuclear export of unspliced viral transcripts. We previously showed that RNA helicase A functionally interacts with CTE and contains a bidirectional nuclear transport domain at the carboxyl terminus. Here we report the identification of a novel human protein, helicase A-binding protein 95 (HAP95), which specifically binds to the carboxyl terminus of RNA helicase A. HAP95 is partially homologous to AKAP95, a member of the A kinase-anchoring protein family, but lacks the protein kinase A binding domain characteristic of this family. HAP95 is a nuclear protein at steady state but shuttles between the nucleus and cytoplasm. Overexpression of HAP95 significantly increases CTE-dependent gene expression but has no effect on general gene expression or that mediated by the Rev/Rev response element of human immunodeficiency virus type 1.

Amino Acid Sequence↗

PubMed2000

Two nuclear localization signals in the HIV-1 matrix protein regulate nuclear import of the HIV-1 pre-integration complex.

Replication of HIV-1 in non-dividing and slowly proliferating cell populations depends on active import of the viral pre-integration complex (PIC) into the cell nucleus. While it is commonly accepted that this process is mediated by an interaction between the HIV-1 PIC and the cellular nuclear import machinery, controversial results have been reported concerning the mechanisms of this interaction. Here, we demonstrate that a recently identified nuclear localization signal within the HIV-1 matrix protein (MA), MA NLS-2, together with previously described MA NLS-1, mediates nuclear import of the HIV-1 PIC. Inactivation of both MA NLSs precluded nuclear translocation of MA and rendered the virus defective in nuclear import and replication in non-dividing macrophage cultures, even when functional Vpr and integrase (IN), two more viral proteins implicated in HIV-1 nuclear import, were present. Taken together, these results indicate that Vpr does not function as an independent nuclear import factor and demonstrate that HIV-1 MA, by virtue of its two nuclear localization signals, regulates HIV-1 nuclear import.

Amino Acid Sequence↗

PubMed2000

Altered expression of tissue-type plasminogen activator and type 1 inhibitor in astrocytes of mouse cortex following scratch injury in culture.

The expression of plasminogen and plasminogen activators (PG/PAs) in reactive astrocytes was examined following scratch injury. In response to injury, casein-degrading activity could be observed around astrocytes. The protein expression of tissue-type plasminogen activator (tPA) was up-regulated, while the free form of urokinase-type plasminogen activator (uPA) was not detected. Consistent with these findings, results obtained with zymograph assay also revealed that tPA activity, but not uPA activity, was up-regulated. Moreover, the addition of 6-amino-caproitic acid (EACA) to casein-covered astrocytes significantly prevented the recovery of the injured astrocytes in a dose-dependent manner. Taken together, our data demonstrate that the expression of PG/PAs in cultured astrocytes is regulated following injury, suggesting that caseinolytic activity is an essential component during the process of astrocyte recovery.

Aminocaproic Acid↗

PubMed2000

Inhibition of AT1 receptor internalization by concanavalin A blocks angiotensin II-induced ERK activation in vascular smooth muscle cells. Involvement of epidermal growth factor receptor proteolysis but not AT1 receptor internalization.

Recent studies of beta(2)-adrenergic receptor suggest that agonist-promoted receptor internalization may play an important role in extracellular signal-regulated kinase (ERK) activation by G protein-coupled receptors. In the present study, we explored the effects of angiotensin II (Ang II) type-1 receptor (AT(1)) internalization on Ang II-induced activation of ERK using the receptor internalization blocker concanavalin A (ConA) and the carboxyl terminus-truncated receptor mutants with impaired internalization. ConA inhibited AT(1) receptor internalization without affecting ligand binding to the receptor, Ang II-induced generation of second messengers, and activation of tyrosine kinases Src and Pyk2 in vascular smooth muscle cells (VSMC). ConA blocked ERK activation evoked by Ang II and the calcium ionophore A23187. Impairment of AT(1) receptor internalization by truncating the receptor carboxyl terminus did not affect Ang II-induced ERK activation. ConA induced proteolytic cleavage of the epidermal growth factor (EGF) receptor at carboxyl terminus and abolished Ang II-induced transactivation of the EGF receptor, which is critical for ERK activation by Ang II in VSMC. ConA also induced proteolysis of erbB-2 but not platelet-derived growth factor receptor. Thus, ConA blocks Ang II-induced ERK activation in VSMC through a distinct mechanism, the ConA-mediated proteolysis of the EGF receptor.

Angiotensin II↗

PubMed2000

Regulation of calcium-sensitive tyrosine kinase Pyk2 by angiotensin II in endothelial cells. Roles of Yes tyrosine kinase and tyrosine phosphatase SHP-2.

Calcium-sensitive tyrosine kinase Pyk2 has been implicated in the regulation of ion channels, cellular adhesion, and mitogenic and hypertrophic reactions. In this study, we have investigated the regulation of Pyk2 by angiotensin II (Ang II) in pulmonary vein endothelial cells. We found that the Ang II-induced tyrosine phosphorylation of Pyk2, which requires the activity of Src family kinase, was specifically regulated by the Src family kinase member, Yes kinase. Moreover, we identified for the first time the constitutive association of Pyk2 with an Src homology 2 (SH2) domain-containing tyrosine phosphatase SHP-2. SHP-2 interacts with Pyk2 through a region other than its SH2 domains. Pyk2 can be dephosphorylated in vitro in SHP-2 immunoprecipitates and in intact cells expressing an NH(2) terminus-truncated form of SHP-2, which lacks the two SH2 domains but has an enhanced phosphatase activity. Ang II activates the endogenous SHP-2. Finally, the SHP-2-mediated dephosphorylation of Pyk2 correlates with the negative effect of SHP-2 on the Ang II-induced activation of extracellular signal-regulated kinase and c-Jun NH(2)-terminal kinase. Thus, the balance of Pyk2 tyrosine phosphorylation in response to Ang II is controlled by Yes kinase and by a tyrosine phosphatase SHP-2 in endothelial cells.

Angiotensin II↗

PubMed2000

Quantitation of Epstein-Barr virus DNA in the blood of adult liver transplant recipients.

BACKGROUND: Posttransplant lymphoproliferation is most often observed in pediatric transplant recipients who experience primary Epstein-Barr virus (EBV) infection at the time of or after transplantation. Lymphoproliferation is believed to be caused by impaired control of EBV-infected cells, which may be of recipient or donor origin. Most studies of EBV infection and lymphoproliferation have focused on the pediatric age group. METHODS: We have undertaken a prospective study of EBV infection in adult liver transplant recipients. Sequentially collected peripheral blood lymphocytes were examined with a recently developed quantitative polymerase chain reaction assay. The assay quantitates EBV DNA genomic titre over a 5 log10 range. RESULTS: Compared with healthy EBV seropositive people not undergoing immunosuppressive therapy, blood EBV DNA titre is elevated in patients with liver disease before transplantation. Overall, highest titres were observed during the first posttransplant month, and in the context of antilymphocyte therapy. In one patient, lymphoproliferation was associated with high titres which fell during reduction of immunosuppressive therapy. In another patient with lymphoproliferation of donor lymphocyte origin, blood EBV DNA titre was not as high. CONCLUSIONS: EBV proliferation is seen in the context of advanced liver disease and after liver transplantation. EBV DNA quantitation is a useful tool to examine the effects of immunosuppression on EBV-associated lymphoproliferation, and may be an essential technique for programs exploring the merits of EBV adoptive immunotherapy.

Adult↗