Biomedical subjects

H Tang

Publications and source records attributed to H Tang.

At least 109 records · Page 6Linked to original sources

PubMed2000

In vivo determination of body composition of rats using magnetic resonance imaging.

Magnetic resonance imaging (MRI) has potential as an instrument to measure body composition because it can discriminate various soft tissues in vivo. These soft tissues include adipose tissue, muscle, organs, and brain. We report on preliminary studies using a 4.2-tesla MRI for measuring body composition in the mouse and rat. We employed image segmentation methods that include an image correction method, a necessary requirement when the images are taken in the presence of nonuniform radio-frequency (RF) coil response. The software for 3-D data segmentation, quantification, correction, image manipulation, and visualization has been developed as a research tool. This method currently is being validated.

Animals↗

PubMed2000

Promoter-proximal pausing on the hsp70 promoter in Drosophila melanogaster depends on the upstream regulator.

RNA polymerase II pauses in the promoter-proximal region of many genes during transcription. In the case of the hsp70 promoter from Drosophila melanogaster, this pause is long-lived and occurs even when the gene is not induced. Paused polymerase escapes during heat shock when the transcriptional activator heat shock factor associates with the promoter. However, pausing is still evident, especially when induction is at an intermediate level. Yeast Gal4 protein (Gal4p) will induce transcription of the hsp70 promoter in Drosophila when binding sites for Gal4p are positioned upstream from the hsp70 TATA element. To further our understanding of promoter-proximal pausing, we have analyzed the effect of Gal4p on promoter-proximal pausing in salivary glands of Drosophila larvae. Using permanganate genomic footprinting, we observed that various levels of Gal4p induction resulted in an even distribution of RNA polymerase throughout the first 76 nucleotides of the transcribed region. In contrast, promoter-proximal pausing still occurs on endogenous and transgenic hsp70 promoters in salivary glands when these promoters are induced by heat shock. We also determined that mutations introduced into the region where the polymerase pauses do not inhibit pausing in a cell-free system. Taken together, these results indicate that promoter-proximal pausing is dictated by the regulatory proteins interacting upstream from the core promoter region.

Animals↗

PubMed2000

Additive antiviral effects of lamivudine and alpha-interferon in chronic hepatitis B infection.

alpha-Interferon has limited efficacy against chronic hepatitis B virus (HBV) infection. Nucleoside analogues may confer greater benefits, however, it is likely that combination therapies will be required for effective control of this infection. We investigated the antiviral effect of lamivudine and interferon therapy in eight patients with high HBV-DNA levels. Six patients received lamivudine/interferon combination therapy followed, after a 6-month drug-free period, with lamivudine monotherapy. Mean HBV viral load (copies/ml) reduction was significantly greater after 4 months of combination therapy (4.3 x 10(3)) compared to an equivalent period of lamivudine monotherapy (2.9 x 10(2)) (P=0.03). Two patients were given 6 months of lamivudine/interferon combination therapy followed immediately by lamivudine monotherapy. Cessation of interferon in these patients led to a rapid 1-2 log10 increase in HBV viral load. These findings suggest that alpha-interferon has a direct antiviral effect on chronic HBV infection, which may be additive to, or synergistic with lamivudine.

Antiviral Agents↗

PubMed2000

Addition of C-terminal histidyl tags to PsaL and PsaK1 proteins of cyanobacterial photosystem I.

In vitro mutagenesis was used to produce two photosystem I mutants of the cyanobacterium Synechocystis sp. PCC 6803. The mutant HK and HL contained hexahistidyl tags at the C-termini of the PsaK1 and PsaL subunits, respectively. The HK mutant contained wild-type amounts of trimeric PS I complexes, but the level of hexahistidine-tagged PsaK1 was found only ten per cent in the PS I complexes and membranes of the wild type level. Therefore, attachment of a tag at the C-terminus interferes with the expression or assembly of PsaK1. In contrast, the HL mutant contained a similar level of tagged PsaL as that in the wild type. However, trimeric PS I complexes could not be obtained from this strain, indicating that the C-terminus of PsaL is involved in the formation of PS I trimers. Hexahistidine-tagged complexes of the HL and HK strains could not be purified with Nickel-affinity chromatography, unless photosystem I was denatured with urea, demonstrating that tagged C-termini of PsaK1 and PsaL were embedded inside of the PS I complex. Protection of the C-terminus from trypsin cleavage further supported this conclusion. Thus, histidine tagging allowed us to demonstrate role of C-termini of two proteins of photosystem I.

Base Sequence↗

PubMed2000

[Plant functional type and its significance in ecological research].

In recent years, plant functional type is a new ecological concept introduced in the research of global change. This paper reviewed the definition, classification, ecological significance of plant functional type. The theories and methodologies of systematic biology were used to understand the concept of plant functional type. And finally, the significance of this term in ecological studies, especially its role in the study of global change and terrestrial ecosystem was explained.

Ecology↗

PubMed2000

[Serum lipoprotein(a) in woman with pregnancy induced hypertension].

OBJECTIVE: To examine lipoprotein(a) level in woman with Pregnancy induced hypertension (PIH) to elucidate the effect of it on the pathogenesis of the disease. METHODS: Serum lipoprotein (a) total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) levels were measured in 20 normal pregnant woman (control group) and 32 pregnant woman with PIH (PIH group). The PIH group was further divided into the following subgroup: mild, moderate, and severe PIH. We used a transmission turbidimetry method to measure serum lipoprotein(a). RESULTS: (1) The serum lipoprotein (a) levels were higher in PIH group than that in control group (228 +/- 187 mg/L vs 106 +/- 93 mg/L). (2) The serum lipoprotein (a) levels were higher in all PIH subgroups than that in control. (3) The serum levels of TC, TG, LDL-C in the PIH group were higher than those in control, while the level of HDL-C in the PIH group was lower than that in control (0.98 +/- 0.16 mmol/L vs 1.09 +/- 0.17 mmol/L). CONCLUSIONS: This study has demonstrated that lipoprotein (a) levels are elevated in pregnant woman with PIH and associated with severity of the disease. It may involved in the pathogenesis of PIH.

Adult↗

PubMed2000

[Expression in E. coli of protein encoded by human esophageal cancer related gene-1].

OBJECTIVE: To express esophageal cancer related gene-1 (ECRG-1)--in E. coli. METHODS: The human ECRG-1 was cloned by RT-PCR. Expression plasmid of the ECRG-1/GST pi fusion gene was constructed and introduced into E. Coli. The fusion protein was induced to express by ITPG. The recombinant protein was identified by Western blot. BALB/C mice were immunized with the protein purified by SDS-PAGE for the preparation of polyclonal antibody. RESULTS: DNA sequencing confirmed that the sequence of ECRG-1 was identical to that of the previously obtained by 5'-RACE technique. Expression of the protein in E. coli was verified by Western blot. The polyclonal antibody obtained from immunized BALB/C mice had a title of 1:3,200. CONCLUSION: The antibody available is useful for the further study of structure and function of the esophageal cancer related protein.

Animals↗

PubMed2000

[Evaluation of modified maze procedure by Doppler tissue imager].

Since 1998 the cardiac surgeons of WCUMS have performed modified maze procedure for treating the patients with rheumatic mitral valve disease accompanied with chronic atrial fibrillation (Af). In this study, echocardiography, especially Doppler Tissue Imager (DTI), was used to evaluate atria contraction and function of such patients before and after the operation. 14 rheumatic mitral disease patients, aged 27-60 years, were chosen; among them, 11 had mitral stenosis, 3 mitral regurgitation. The control group consisted of 16 cases, aged 24-67 years, with normal echocardiogram. Before and half-1 year after the operation, left atrium, left ventricle, right atrium and ventricle were measured, and cardiac function and posterior wall motion of left atrium were measured. Velocity of mitral valve annual and tricuspid valve annual was measured in DTI. The results showed: There was no age difference between the two groups. The motion of posterior wall of left atrium was 4.18 +/- 0.37 mm in the operation group, 4.09 +/- 0.29 mm in the control group (P > 0.05). No difference in velocity of mitral/tricuspid valve annual between the two groups was observed; 3 peaks of mitral valve annual were S 0.11 +/- 0.02, e 0.11 +/- 0.01, a 0.09 +/- 0.01 (m/s) in operation group, and S 0.08 +/- 0.00, e 0.10 +/- 0.01, a 0.08 +/- 0.01 (m/s) in control group, (P > 0.05, respectively); 3 peaks of tricuspid valve annual were S 0.10 +/- 0.01 vs 0.11 +/- 0.08, e 0.11 +/- 0.08 vs 0.10 +/- 0.01, a 0.10 +/- 0.10 vs 0.09 +/- 0.01 (m/s), (P > 0.05, respectively). The diameter of left atrium after operation in cases of mitral stenosis decreased significantly, compared with that before operation (P < 0.01). The diameter of right atrium after operation decreased significantly, compared with that before operation (P < 0.01). There was no significant change in right ventricle/left ventricle/EF and FS. The diameter of left atrium after operation in cases of mitral regurgitation decreased significantly, compared with that before operation (P < 0.01). The diameter of left ventricle after operation decreased significantly, compared with that before operation (P < 0.05). No significant change in right ventricle/right atrium/EF and FS was noted. The authors conclude the DTI, as a new diagnostic method in echocardiography, has high sensitivity and is less influenced when used to observe motion of atrium-ventricle annual influenced. It can avoid the error caused by deviation of blood displacement. In the rheumatic mitral valve disease patients who had mitral valve replacement and modified maze procedure, atrial contraction respores, the risk of thromboembolism decreases and prognosis improves. So the operation is worth doing.

Adult↗

PubMed2000

[Preliminary echocardiographic evaluation on prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis].

The purpose of this study was to evaluate the preliminary results after prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis. 20 patients had received operation with expanded polytetrafluoroethylene(e-PTFE) as artificial chordade. The patients were followed up by means of echocardiography. The time of follow-up study varied from 4 to 18 months with a mean of 6 months. The left atrial, ventricular dimension as well as ventricular function were assessed. In addition, the length of artificial chorade and obstruction of left ventricular outflow track were observed. The results showed that left atrial diameter (LAD, from 57.59 +/- 13.51 mm to 47.05 +/- 9.55 mm), left ventricular end-diastolic dimension (LVEDD, from 46.23 +/- 12.56 mm to 42.41 +/- 10.86 mm), left ventricular end-systolic dimension (LVESD, from 33.50 +/- 10.20 mm to 29.68 +/- 8.40 mm) decreased (P < 0.01), and ejection fraction (EF, from 52.59 +/- 11.89% to 58.36 +/- 8.03%) increased (P < 0.05) after operation. There were no significant changes of fractional shortening (FS, from 29.23 +/- 8.99% to 31.05 +/- 6.08%). The length of artificial chorade ranged from 2.6 cm to 4.3 cm (the mean, 3.2 cm). There was no case of obstruction of left ventricular outflow track. It is believed that the result of preliminary echocardiographic observation on prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis is satisfactory.

Adult↗

PubMed2000

[Study of spontaneous echo contrast in patients with rheumatic mitral stenosis by transesophageal echocardiography].

Spontaneous echo contrast (SEC) is common in the areas of slow blood flow. This study was conducted to examine the correlation of SEC and left atrial appendage function, atrial fibrillation (Af) and thrombus in patients with rheumatic mitral stenosis. The transthoracic and multiplane transesophageal echocardiograms were performed on 117 patients(mean age 42.22 +/- 10.79 years). Left atrial size, left atrial appendage area, mitral valve area, left atrial appendage flow peak emphatic velocity and full velocity were measured. The presence of SEC and thrombus in the left atrium and appendage was noted. The results showed that among the patients, 57 had normal sinus rhythm, 60 had Af; 19 had thrombus, 98 had no thrombus; 71 had SEC and 46 had no SEC. Compared with the patients without SEC, the patients with SEC showed greater incidence of thrombus (28.76% vs 0, P < 0.05), higher rate of Af (69.01% vs 23.91%, P < 0.05), larger LAD (46.93 +/- 0.85 mm vs. 41.76 +/- 1.05 mm, P < 0.05), larger LAA area (8.06 +/- 0.32 cm2 vs 6.92 +/- 0.31 cm2, P < 0.05), smaller MVA area (1.07 +/- 0.23 cm2 vs 1.32 +/- 0.35 cm2, P < 0.05), lower LAA flow peak emphatic velocity (0.17 +/- 0.01 m/s vs 0.32 +/- 0.02 m/s, P < 0.05), and lower LAA full velocity (0.18 +/- 0.01 m/s vs 0.31 +/- 0.03 m/s, P < 0.05). These findings indicate that the presence of SEC is associated with significantly greater incidence of thrombus, higher rate of Af, larger LAD and LAA area, smaller MVA area, lower LAA flow peak emphatic velocity and full velocity. Atrial fibrillation, the diameter of left atrium and the area of mitral valve are independent predictors of SEC. SEC is significantly associated with LAA function and thrombus formation.

Adolescent↗

PubMed2000

[Transthoracic three-dimensional echocardiography for determination of left ventricular mass in patients with dilated cardiomyopathy].

This study was performed to compare left ventricular mass (LVM) measurement by one- (1D), two- (2D) and 3D echocardiography with magnetic resonance imaging (MRI) in patients with dilated cardiomyopathy (DCM). 36 patients with DCM underwent imaging by conventional 1D and 2D echocardiography as well as transthoracic 3D echocardiographic data acquisition. Also patients were imaged with cardiac MRI. LVM was determined. There was no significant correlation (r = 0.42, P > 0.05) for measuring LVM between 1D echocardiography and MRI in patients with DCM. A significant correlation was obtained between 2D echocardiography and MRI (r = 0.64, P < 0.01) and between 3D and MRI (r = 0.78, P < 0.01) in determination of LVM. Compared with 1D and 2D echocardiography, the 3D analysis achieved a significantly higher agreement with the MRI results (1D; 399.2 g, 2D: 285.9 g, 3D: 172.6 g versus MRI: 199.1 g). Interobserver variability was 5.1% for measuring LVM by 3D echocardiography. These results suggest that LVM of patients with DCM can be accurately determined by transthoracic 3D echocardiography and this method could be used in clinical practice.

Adolescent↗

PubMed2000

[Cloning and tissue expression pattern analysis of the human citrate synthase cDNA].

Tricarboxylic acid (TCA) cycle is an important way to generate ATP, which is widely distributed in the cells of animal, plant or microorganism. It catalyses the catabolism of sugar as well as protein and fat. Citrate synthase plays a key role in regulating TCA cycle and is responsible for catalysing the synthesis of citrate from oxaloacetate and acetyl CoA. Screening of genomic informatics was performed by using pig citrate synthase cDNA as a probe and a contig which is 1636 bp long and has highly homologous to the pig citrate synthase cDNA was obtained from selected ESTs with the ASSEMBLY program. According to the sequence of this contig, a pair of primers was designed and used to amplify cDNA libraries. A 1492 bp cDNA containing an open reading frame encoding 466 amino acids was cloned from human testis and skeletal muscle cDNA libraries. The deduced amino acid sequence of the cDNA showed 95%, 92% and 60.9% identity to pig, chicken and yeast citrate synthase respectively. Because the deduced amino acids sequence contains a highly conserved motif of citrate synthase from three different species, it is believed that this cDNA may be a transcript of human citrate synthase gene. Northern analysis showed that the human citrate synthase was expressed at high level in heart and muscle, at middle level in brain, kidney and pancreas tissues, not detectable in thymus and small intestine tissues, and at low level in other nine tested human tissues.

Amino Acid Sequence↗

PubMed2000

[Effect of ethyl acetate extract of Eclipta prostrata on mice of normal and immunosupression].

OBJECTIVE: The regulatory effects of ethyl acetate extract of Eclipta prostrata (EAEEP) on immune function were studied. METHODS: The experimental immunosuppressive mice models were induced by injection of cyclophosphamide or hydrocartisone. RESULTS: The index of spleen in normal mice were decreased significantly. So was the level of hemolysin in serum, Delayed trpe hypersensitivity was also inhibited at the same condition. But EAEEP can increase all these indexes in immunosuppressive mice. CONCLUSION: EAEEP possesses obvious regulatory action on immune function in mice.

Acetates↗

PubMed2000

[Construction of plasmids expressing hepatitis E virus antigen fragments and their combinations].

OBJECTIVE: Several different regions of the HEV antigen were expressed in Escherichia coli and their immunological characteristics were simply evaluated. METHODS: Three coding sequences of immunodominant antigenic regions in structural protein of the hepatitis E virus (ORF2.1: 6287-6403nt, ORF2.2: 6743-7126nt, ORF3: full length of ORF3) were amplified by RT-PCR from the fecal supernatants of macaques experimentally infected with HEV. These three fragments were inserted into the pThioHisC expression vector separately or fused in line by (Gly)n short arms. After identified by DNA sequence analysis, these six recombinant plasmids were transformed into Escherichia coli, and immunology characteristics of expressed antigen fragments were evaluated by Western blotting. RESULTS: All six genes were successfully expressed in Escherichia coli. Western blotting assay showed that the recombinant proteins specifically reacted with the serum antibody from hepatitis E patient in various degrees. CONCLUSION: Artificial antigen based on strung epitopes provides a promising strategy for detection and prevention of HEV infection.

Antigens, Viral↗

PubMed1999

Analysis of the nifHDK operon and structure of the NifH protein from the unicellular, diazotrophic cyanobacterium, Cyanothece strain sp. ATCC 51142(1).

Cyanothece sp. ATCC 51142 is a unicellular, diazotrophic cyanobacterium that demonstrates diurnal rhythms for photosynthesis and N(2) fixation, with peaks of O(2) evolution and nitrogenase activity approximately 12 h out of phase. We cloned and sequenced the nifHDK operon, and determined that the amino acid sequences of all three proteins were highly conserved relative to those of other cyanobacteria and bacteria. However, the Fe-protein, encoded by the nifH gene, demonstrated two differences from the related protein in Azotobacter vinelandii, for which a 3-D structure has been determined. First, the Cyanothece Fe-protein contained a 37 amino acid extension at the N-terminus. This approximately 4 kDa addition to the protein appeared to fold as a separate domain, but remained a part of the active protein, as was verified by migration on acrylamide gels. In addition, the Cyanothece Fe-protein had amino acid differences at positions involved in formation of the Fe-protein dimer-dimer contacts in A. vinelandii nitrogenase. There were also changes in residues involved with interaction between the Fe-protein and the MoFe-protein when compared with A. vinelandii. Since the Cyanothece Fe-protein is quickly degraded after activity, it is suggested that the extension and the amino acid alterations were somehow involved in this degradative process.

Amino Acid Sequence↗

PubMed1999

A Comparative Study of Surface Acid-Base Characteristics of Natural Illites from Different Origins.

The acid-base characteristics of naturally occurring illites, collected from different locations, were investigated by potentiometric titrations. The experimental data were interpreted using the constant capacitance surface complexation model. Considerable release of Al and Si from illite samples and subsequent complexation or precipitation of hydroxyl aluminosilicates generated during the acidimetric forward titration and the alkalimetric back titration, respectively, were observed. Therefore, the acidimetric supernatant, rather than the neutral one, was regarded as the system blank for each illite suspension to yield the surface site concentrations. In order to describe the acid-base chemistry of aqueous illite surfaces, two surface proton-reaction models, introducing the corresponding reactions between the dissolved aluminum species and silicic acid, as well as a surface Al-Si complex on homogeneous illite surface sites, were proposed as follows: The K(f2) constant in Model II was obtained by simulating the complex formation between the dissolved aluminum species and silicic acid that occurred in acidimetric supernatant when the hydroxide was added. Additionally, the following cation exchange reaction was also considered for a special case, where a large amount of K(+) is released during the corresponding acidimetric titration, in which a high concentration of protons are consumed. Optimization results indicated that both models could provide a good description of the titration behavior for all aqueous illite systems in this study. The intrinsic acidity constants for the different illites were similar in Model I, showing some generalities in their acid-base properties. Model I may be considered as a simplification of Model II, evident in the similarities between the corresponding constants. In addition, the formation constant for surface Al-Si species (complexes or precipitates) is relatively stable in this study. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Poor outcome in patients with diabetes mellitus undergoing liver transplantation.

BACKGROUND: Relatively few studies have examined the influence of pretransplant diabetes on survival after an orthotopic liver transplant (OLT), and those published to date show only minor increases in infection rates among diabetics and no increase in mortality. METHODS: We examined the effect of diabetes mellitus on survival after OLT. 1005 adults underwent OLT between 1982 and May 1997. Seventy-eight patients with pretransplant diabetes mellitus (7.8% of all OLT, 38 insulin treated, 25 tablet treated, 15 diet controlled) were identified and compared with controls matched for age, sex, and date of first transplant and also with all nondiabetic adult liver recipients undergoing OLT during the same period. RESULTS: In patients undergoing OLT survival was worse in diabetics than in the comparison group (P=0.002) and vs. all adult nondiabetics undergoing (n=927) (P=0.004); in diabetics with alcoholic liver disease (ALD) vs. all nondiabetics with alcoholic liver disease (P= <0.0001); and in insulin-treated compared with non-insulin-treated diabetics (P=0.05). Multivariate analysis showed type of diabetes (P=0.001) and ALD (P=0.024) to be the most significant independent variables adversely affecting survival. Survival in diabetics undergoing OLT could be further stratified according to whether diabetics were insulin treated. CONCLUSIONS: Poorer outcome in the diabetics undergoing OLT, particularly in those with ALD, suggests the need for a more detailed pre-OLT assessment of these patients, particularly those with insulin and tablet controlled diabetes.

Adult↗

PubMed1999

Heterochromatic silencing of Drosophila heat shock genes acts at the level of promoter potentiation.

In a variety of organisms, genes placed near heterochromatin are transcriptionally silenced. In order to understand the molecular mechanisms responsible for this block in transcription, high resolution in vivo chromatin structure analysis was performed on two heat shock genes, hsp26 and hsp70. These genes normally reside in euchromatin where GAGA factor and RNA Pol II are present on the promoter prior to heat shock induction. P-element transformation experiments led to the identification of stocks in which these two genes were inserted within heterochromatin of the chromosome 4 telomeric region. These transgenes exhibit silencing that is partially suppressed by mutations in the gene encoding HP1. Micrococcal nuclease analysis revealed that the heterochromatic transgenes were packaged in a more regular nucleosome array than when located in euchromatin. High resolution DNase I analysis demonstrated that GAGA factor and TFIID were not associated with these promoters in heterochromatin; potassium permanganate experiments showed a loss of Pol II association. Taken together, these data suggest that occlusion of trans-acting factors from their cis- acting regulatory elements leading to a block in promoter potentiation is a mechanism for heterochromatin gene silencing.

Animals↗