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Biomedical subjects

Hong Tang

Publications and source records attributed to Hong Tang.

At least 55 records · Page 3Linked to original sources
PubMed2004

Insulin resistance and endothelial dysfunction in type 2 diabetes patients with or without microalbuminuria.

OBJECTIVE: To evaluate the relationship between insulin resistance and endothelial function in type 2 diabetes patients with or without microalbuminuria and to explore the pathophysiological mechanisms of the increased macrovascular risk in type 2 diabetes mellitus. METHODS: Twelve type 2 diabetes patients with microalbuminuria (urinary albumin 30-300 g/mg creatinine, DM-MA) and 12 type 2 diabetes patients without microalbuminuria (urinary albumin <30 g/mg creatinine, DM-NA) were recruited, matched for their sex, age, body mass index (BMI), diabetes duration, antidiabetic therapy. Their hemoglobin (HbA1C) was less than 7.5% and the blood pressure was lower than 140/90 mmHg. None had evidence of macrovascular disease and serum cholesterol levels were normal. Twelve healthy volunteers (C) were enrolled as controls. All subjects received a hyperinsulinemic euglycemic clamp study (insulin infusion rate, 120 mU/m2/min) to assess the peripheral glucose disposal rate (GDR) in the steady state and had a high-resolution ultrasonography to measure vasodilation in the brachial artery diameter in response to reactive hyperemia (endothelium-dependent) and administration of glyceryl trinitrate (endothelium-independent). Plasma free fatty acids (FFAs), plasminogen activator inhibitor type I (PAI-1), and von Willebrand factor (vWF) were also measured. RESULTS: The GDR was lower in type 2 diabetes patients with microalbuminuria (7.90 +/- 1.79 mg/kg/min) than in patients without microalbuminuria (9.46 +/- 1.59 mg/kg/min, P<0.05), and the GDR in both diabetes groups was decreased, compared with the findings from the healthy control group (13.06 +/- 1.98 mg/kg/min, P<0.01). Plasma FFAs concentration was different among the three groups (DM-MA-1008 +/- 229 mol/l, DM-NA-675 +/- 201 mol/l, P<0.01; C-364 +/- 169 mol/l, P<0.01). Endothelium-dependent vasodilation was impaired in the microalbuminuric patients (8.0 +/- 3.8%) compared with the normoalbuminuria patients (9.7 +/- 4.3%, P>0.05) and the healthy controls (14.2 +/- 5.0, P<0.05). Plasma PAI-1 and vWF levels increased in the microalbuminuric patients (61.9 +/- 18.2 ng/ml, 126.8 (76.5-212.7) %) compared with the levels in the normoalbuminuric patients (45.4 +/- 16.3 ng/ml, 87.9 (84.2-114) %) (PAI-1, P<0.05; vWF, P>0.05) and in the healthy controls (33.6 +/- 10.6 ng/ml, 67.2 (61.5-75.4) %, both P<0.01). In addition, the partial correlation analysis revealed a significant positive correlation between GDR and endothelium-dependent vasodilation (r=0.465, P<0.01, n=36), and a negative correlation between GDR and plasma FFA levels (P<0.05). CONCLUSIONS: Compared with type 2 diabetes patients with normoalbuminuria, patients with microalbuminuria had more severe insulin resistance, more prominent endothelial dysfunction, and higher plasma FFA, PAI-1, and vWF levels. Therefore we speculate that insulin resistance and endothelial dysfunction may act within the metabolic syndrome to increase the cardiovasular risk in this subset of patients, and improving insulin resistance and endothelial dysfunction may reduce the morbidity and mortality from macrovascular complications in type 2 diabetes patients.

Aged↗
PubMed2004

[Axis registration and image interpolation of rotary scanning echocardiogram].

The object of this study was to work at accurate axis registration and interpolation methods for multi-dimension reconstruction of rotary scanning ultrasonic medical images. At first, time-field curves of the images' axes were analyzed according to their characteristic points and the axial direction registration was realized. Similar matrix was used to find registration pixels line near the axes of two images. Auto-correlation function and Fourier spectrum were used to evaluate the effects of axes registration. Second, an interpolation method was studied for the special space distribution of rotary scanning images. Results of experiments indicate that the axes registration and interpolation methods were suitable to rotary scanning medical images. The quality of reconstruction can be greatly improved by registration-based interpolation methods.

Algorithms↗
PubMed2004

[Fast volume rendering of echocardiogram with shear-warp algorithm].

Shear-warp is a volume rendering technology based on object-order. It has the characteristics of high speed and high image quality by comparison with the conventional visualization technology. The authors introduced the principle of this algorithm and applied it to the visualization of 3-D data obtained by interpolating rotary scanning echocardiogram. The 3-D reconstruction of the echocardiogram was efficiently completed with high image quality. This algorithm has a prospective application in medical image visualization.

Adult↗
PubMed2004

[Method for measuring different phases of left ventricular systole period with ultrasonic Doppler and synchronism electrocardiogram in normal persons].

This study of methodology was aimed to assess the feasibility of measuring different phase of left ventricular systole period with ultrasonic Doppler and synchronism electrocardiogram. We measured the phases of left ventricular systole period and left ventricular volumes in 13 normal persons, using spectrum of aortic valve orifice flow and synchronism electrocardiogram. The values measured by routine method and by Doppler method were compared. The correlation and agreement between the measures ascertained by the two ways were analyzed. The time parameters of end systole of left ventricule showed no significant difference between the two ways (P>0.05); there was high linear correlation between the two parameters (r=0.91, P<0.01); there were good agreements between the two parameters of the two ways by Bland-Altman analysis. The volume parameters of left ventricular systole end showed no significant difference between the two ways (P>0.05); there was high linear correlation between the two parameters (r=0.97, P<0.01); there were good agreements between the two volume parameters of the two ways. The volume in the left ventricular systole end determined by Doppler method and the volume in the left ventricular diastole end determined by the routine method showed no significant difference (P>0.05); there was high linear correlation between the two parameters (r=0.98, P<0.01); there was good agreement between the two volume parameters of the two ways. It is feasible to measure different phases of left ventricular systole period with the combined use of ultrasonic Doppler and synchronism electrocardiogram, and this combinaterial method and the routine method can be replaced with each other according to the clinical setting.

Adult↗
PubMed2004

[Isolation and cultivation of mouse bone marrow mesenchymal stem cells].

To establish the best condition of isolation and cultivation of mouse bone marrow mesenchymal stem cells (BMSCs) in vitro, we isolated BMSCs from BALB/C mouse using density gradient centrifugation and adherent selecting. The effects of different centrifuge power, adherent time, serum concentration and cell density on the isolation and cultivation of BMSCs were investigated. The best isolating condition is: 500g x 30min, 24 hours adhering. The best cell density is 12-20 x 10(5)/ml of primary cells and 6.4-25.6 x 10(4)/ml of secondary cells. The best serum concentration is 10%. More than 90% of subcultured cells were adhesive in 8 hours. Thus we have established a cell biological method of isolation and cultivation of BMSCs.

Animals↗
PubMed2003

Identification of the protein-protein contact site and interaction mode of human VDAC1 with Bcl-2 family proteins.

Bcl-2 family of proteins plays differential roles in regulation of mitochondria-mediated apoptosis, by either promoting or inhibiting the release of apoptogenic molecules from mitochondria to cytosol. Bcl-2 family proteins modulate the mitochondrial permeability through interaction with adenine nucleotide translocator (ANT), voltage-dependent anion channel (VDAC), ADP/ATP exchange, or oxidative phosphorylation during apoptosis. Although the mitochondrial homeostasis is affected by the relative ratio of pro- and anti-apoptotic Bcl-2 family members, the molecular mechanism underlying the release of mitochondrial intermembrane proteins remains elusive. Here we reported the biochemical evidence that both pro-apoptotic Bax and anti-apoptotic Bcl-X(L) might simultaneously contact the putative loop regions of human VDAC1, and the existence of VDAC1-Bax-Bcl-X(L) tertiary complex in vitro suggested that VDAC1 channel conformation and mitochondrial permeability could be determined by the delicate balance between Bax and Bcl-X(L).

Binding Sites↗
PubMed2003

One-step on-column affinity refolding purification and functional analysis of recombinant human VDAC1.

The outer mitochondrial membrane porin, voltage-dependent anion-selective channel (VDAC), is believed to play an important role in mediating mitochondria-dependent apoptosis. However, detailed structure-function studies of VDAC have been hindered by the difficulties to obtain a soluble, correctly folded, and fully active form of the recombinant VDAC and its mutant variants due to its transmembrane nature. Here we report a high-throughput one-step chromatographic procedure in purification of recombinant human VDAC1 (rhVDAC1) protein overexpressed in bacteria. The improved methodology could generate a large quantity of rhVDAC1 with correct folding in terms of the secondary structure, with full biological activities in mediating cytochrome c release and in interaction with Bcl-X(L). The method will significantly benefit genetic, biochemical, and structural studies of this critical channel protein.

Chromatography, Affinity↗
PubMed2003

Crystal structure of tabtoxin resistance protein complexed with acetyl coenzyme A reveals the mechanism for beta-lactam acetylation.

Tabtoxin resistance protein (TTR) is an enzyme that renders tabtoxin-producing pathogens, such as Pseudomonas syringae, tolerant to their own phytotoxins. Here, we report the crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55A resolution. The binary complex forms a characteristic "V" shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). A single-step mechanism is proposed to explain the function of three conserved residues, Glu92, Asp130 and Tyr141, in catalyzing the acetyl group transfer to its substrate. We also report that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members.

Acetyl Coenzyme A↗
PubMed2003

Functional interaction between RNA polymerase alpha subunit C-terminal domain and sigma70 in UP-element- and activator-dependent transcription.

We show that the Escherichia coli RNA polymerase (RNAP) alpha subunit C-terminal domain (alphaCTD) functionally interacts with sigma(70) at a subset of UP-element- and activator-dependent promoters, we define the determinants of alphaCTD and sigma(70) required for the interaction, and we present a structural model for the interaction. The alphaCTD-sigma(70) interaction spans the upstream promoter and core promoter, thereby linking recognition of UP-elements and activators in the upstream promoter with recognition of the -35 element in the core promoter. We propose that the alphaCTD-sigma(70) interaction permits UP-elements and activators not only to "recruit" RNAP through direct interaction with alphaCTD, but also to "remodel" RNAP-core-promoter interaction through indirect, alphaCTD-bridged interactions with sigma(70).

Alanine↗
PubMed2003

Cloning of HBsAg-encoded genes in different vectors and their expression in eukaryotic cells.

AIM: To compare the efficiency of different plasmids as DNA vectors by cloning three HBsAg-encoded genes into two eukaryotic expression vectors, pRc/CMV and pSG5UTPL/Flag, and to express HBsAg S, MS, and LS proteins in SP2/0 cells, and to establish monoclone SP2/0 cell strains that are capable of expressing S or S2S proteins stably. METHODS: Segments of S, preS2-S, preS1-preS2-S genes of Hepatitis B virus were amplified by routine PCR and preS1-S fragment was amplified by Over-Lap Extension PCR. The amplified segments were cleaved with restricted endonuclease Hind III/Not I followed by ligation with pRc/CMV, or BamHI/EcoR I followed by ligation with pSG5UTPL/Flag. After the plasmid vectors were cleaved with the correspond enzymes, the amplified segments were inserted into pRc/CMV or pSG5UTPL/Flag plasmid vectors with T4 DNA ligase. KOZAK sequence was added before the initial ATG code of each fragment using specific primer. The inserted segments in the recombinant plasmids were sequenced after subcloning. BALB/c mice myeloma cells (SP2/0 cell line) were transfected with the recombinant plasmids. The expressions of the different recombinants were Compared by Western-blot, using a monoclonal anti-HBs antibody as the primary antibody and peroxidase-labeled multi-linker as the secondary. Stable SP2/0-pRc/CMV-S or SP2/0- pRc/CMV-MS clones were established through clone screening with G418. RESULTS: Fragments with anticipated size were harvested after PCR. After recombination and screening, the sequences of the inserted segments in the recombinants were confirmed to be S, preS2S, preS1-preS2S and preS1S encoding genes, determined by sequencing. The results of Western-blot hybridization were positive for the anticipated proteins. Among them, pRc/CMV-S or pRc/CMV-MS demonstrated the highest expressing their respective antigen. CONCLUSION: Eight recombinant plasmids expressing S, M, L or preS1S proteins are obtained. For hepatitis surface antigen expression in eukaryotic cells, the vector pRc/CMV is superior to pSG5UTPL/Flag, and pRc/CMV-S and pRc/CMV-MS are the most efficient in the pRc/CMV clones. SP2/0 cells stably expressing HBsAg are established, and may be used as target cells for evaluating the CTL activity of a DNA vaccine in vitro.

Animals↗
PubMed2003

Pathomorphological study on location and distribution of Kupffer cells in hepatocellular carcinoma.

AIM: To clarify the location and distribution of Kupffer cells in hepatocellular carcinoma (HCC), and to investigate their role in hepatocarcinogenesis. METHODS: Kupffer cells were immunohistochemically stained by streptavadin-peroxidase conjugated method (S-P). The numbers of Kupffer cells in cancerous, para-cancerous and adjacent normal liver tissues of 48 HCCs were comparatively examined. RESULTS: The mean number of Kupffer cells in cancerous, para-cancerous and adjacent normal liver tissues was 12.7+/-6.8, 18.1+/-8.2 and 18.9+/-7.9 respectively. The number of Kuppfer cells in cancerous tissues was significantly lower than that in para-cancerous tissues (t=2.423, P<0.05) and adjacent normal liver tissues (t=2.521, P<0.05). As tumor size increased, the number of Kupffer cells in cancerous tissues significantly decreased (F=4.61, P<0.05). Moreover, there was also a significant difference in the number of Kupffer cells among well-differentiated, moderately-differentiated and poorly-differentiated cases(F=4.49, P<0.05). CONCLUSION: This study suggests that decrease of Kupffer cells in HCCs may play an important role in the carcinogenesis of HCC, the number of Kupffer cells in HCC is closely related to the size and differentiation grade of the tumor.

Carcinoma, Hepatocellular↗
PubMed2003

[Early indexes to predict the therapeutic effect of interferon on chronic hepatitis B].

OBJECTIVE: To summarize the clinical changing characters of the clinical markers after interferon treatment in chronic hepatitis B (CHB) and make out practical indexes to predict the effect. METHODS: 150 CHB patients were randomly divided into two groups: therapeutic group (90) and control group (60) in the prospective controlled trial. The levels of endogenous interferon before treatment, interferon antibody at the end of the second month and fourth month after treatment, alanine aminotransferase (ALT) and HBV DNA in the serum were detected. Then the data was analysed to find out indexes for predicting the effect. RESULTS: (1) The clearance rate of HBeAg had no significant difference in age except for 20 - 30 and 30 - 40 (t > 2.331 2, P < 0.01). (2) It was more effective if ALT level was higher than 400 U/L before treatment and it decreased more than 50% two months after treatment. (3) The patients whose HBV DNA was negative (dot hybridization) or less than 10(6) copies/ml before treatment had higher rate of HBeAg clearance. (4) There was no effect on patients whose interferon antibody turned positive at the end of the second month. (5)A predictive method of comprehensive factors was made out, whose sensitivity, specificity, and accuracy were 80%, 100% and 90%, respectively. CONCLUSION: The clinical characters of these Chinese patients are different from those of the westerners and the effects of interferon have close relation to the levels of ALT, HBV DNA and interferon antibody.

Adjuvants, Immunologic↗
PubMed2003

[Cloning and sequence analysis of the molecular-adjuvant gene of the complement C3d of mouse].

OBJECTIVE: Considering that the complement C3d plays a stronger positive role in the control of immunologic system, we constructed the recombinant plasmid of the molecular-adjuvant gene of the complement C3d in order to enhance the immunologic efficacy of the gene vaccine. METHODS: The main points were amplifying the segment of complement C3d gene by using of PCR; inserting it into PGEM-T; detecting it by digesting with Eco RI and sequencing; the whole length being 897 bp; then sub-cloning it into pVAX1. RESULTS: The DNA sequencing confirmed the C3d sequence. CONCLUSION: We have successfully cloned the gene of C3d and constructed the recombinant plasmid of pVAX1 C3d.

Animals↗
PubMed2003

Construction of recombinant adenoviral vector overexpressing human HIF-1alpha gene.

Hypoxia inducible factor 1 (HIF-1) is a heterodimeric transcription factor that plays an important role in oxygen homeostasis. In response to low level of oxygen, subunit HIF-1alpha expression is upregulated and transactivates its target genes essential for energy metabolism, erythropoiesis and vascular development. HIF-1alpha is thought to be able to protect hypoxic cells from apoptosis or necrosis under ischemic and anoxic conditions, the major trauma factors that affect the recovery of brain and spinal cord injury. Here we report the construction of recombinant adenovirus vector overexpressing HIF-1alpha intended for gene therapy against desired neuronal injuries. The recombinant vector could be packaged and yielded significantly high viral titers at 2 x 10(13) CFU in HEK293T cells and good expression levels of HIF-1alpha when superinfected in Hela cells.

Adenoviridae↗
PubMed2002

A pregenomic RNA sequence adjacent to DR1 and complementary to epsilon influences hepatitis B virus replication efficiency.

Hepatitis B virus (HBV) possesses a 3.2-kb partially double-stranded DNA genome that is generated inside the nucleocapsid by the reverse transcription of the 3.5-kb pregenomic viral transcript. The initial steps in viral replication involve the recognition of an encapsidation signal termed epsilon (epsilon) at the 5'-end of the pregenomic RNA by the HBV polymerase. The polymerase-bound pregenomic RNA is subsequently incorporated into an immature nucleocapsid particle and minus-strand HBV DNA synthesis is initiated utilizing the bulge region of epsilon as a template and a tyrosine residue in the amino-terminal region of the polymerase as a primer. Three nucleotides complementary to the 3'-end of the bulge region of epsilon are synthesized and subsequently translocated with the polymerase molecule to the acceptor site located in the DR1 sequence present at the 3'-end of the pregenomic RNA. Using mutagenesis analysis, a sequence element designated phi (phi) located upstream of the 3' DR1 sequence has been identified that is complementary to epsilon and is important for efficient viral replication. This element may bring the 3' DR1 sequence into proximity with the three nucleotide primer synthesized at the bulge of epsilon and facilitate primer translocation to the 3' DR1 acceptor sequence. Sequence elements with similar proximity to the 3' DR1 sequences and complementarity to epsilon are present in the woodchuck hepatitis virus (WHV) and duck hepatitis B virus (DHBV), suggesting the phi regulatory element may be phylogenetically conserved due to its functional importance in hepadnavirus minus-strand DNA synthesis.

3' Untranslated Regions↗
PubMed2002

Functional characterization of the interferon regulatory element in the enhancer 1 region of the hepatitis B virus genome.

An interferon-stimulated response element (ISRE)/interferon regulatory element (IRE) spanning nucleotide coordinates 1091-1100 is present in the enhancer 1/X gene promoter region of the hepatitis B virus (HBV) genome. In the context of a minimal promoter element, the enhancer 1/X gene promoter ISRE/IRE was shown to be a functional regulatory site capable of mediating interferon alpha- (IFNalpha) and interferon-stimulated gene factor 3 (ISGF3)-specific transcriptional activation in transient transfection analysis. The enhancer 1/X gene promoter ISRE/IRE was also shown to mediate interferon regulatory factor (IRF) 1 and IRF7 activation of transcription from a minimal promoter construct. In contrast, IFNalpha and the IRFs had minimal effect on HBV transcription and replication in the context of the viral genome in cell culture.

Base Sequence↗