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Biomedical subjects

Fan Zhang

Publications and source records attributed to Fan Zhang.

At least 91 records · Page 5Linked to original sources
PubMed2005

Three new diterpene alkaloids from the roots of Aconitum nagarum var. lasiandrum.

Three new diterpene alkaloids, 16,17-dihydro-12 beta,16 beta-epoxynapelline (1), N-deethyl- N-methyl-12-epi-napelline (2) and 11- epi-16 alpha,17-dihydroxylepenine (3), along with twenty-six known alkaloids (4 - 29) were isolated from the roots of Aconitum nagarum var. lasiandrum. The chemical structures of the new compounds were established by HR-MS as well as 1D- and 2D-NMR spectroscopic analysis. The absolute stereochemistry of 1 was confirmed by X-ray crystallography.

Aconitum↗
PubMed2005

Ubiquitylation of Cdk9 by Skp2 facilitates optimal Tat transactivation.

By recruiting the positive transcriptional elongation factor b (P-TEFb) to paused RNA polymerase II, the transactivator Tat stimulates transcriptional elongation of the human immunodeficiency virus type 1 (HIV-1) genome. We found that cyclin-dependent kinase 9 (Cdk9), the catalytic subunit of P-TEFb, is ubiquitylated in vivo. This ubiquitylation depended on the Skp1/Cul1/F-box protein E3 ubiquitin ligase Skp2. Likewise, Tat required Skp2 since its transactivation of the HIV-1 long terminal repeat decreased in primary mouse embryonic fibroblasts, which lacked Skp2. The ubiquitylation of Cdk9 by Skp2 facilitated the formation of the ternary complex between P-TEFb, Tat, and transactivation response element. Thus, our findings underscore the requirement of ubiquitylation for the coactivator function in regulating HIV-1 transcriptional elongation.

Animals↗
PubMed2005

Runx1 binds positive transcription elongation factor b and represses transcriptional elongation by RNA polymerase II: possible mechanism of CD4 silencing.

Runx1 binds the silencer and represses CD4 transcription in immature thymocytes. In this study, we found that Runx1 inhibits P-TEFb, which contains CycT1, CycT2, or CycK and Cdk9 and stimulates transcriptional elongation by RNA polymerase II (RNAPII) in eukaryotic cells. Indeed, its inhibitory domain, spanning positions 371 to 411, not only bound CycT1 but was required for silencing CD4 transcription in vivo. Our chromatin immunoprecipitation assays revealed that Runx1 inhibits the elongation but not initiation of transcription and that RNAPII is engaged at the CD4 promoter but is unable to elongate in CD4(-) CD8(+) thymoma cells. These results suggest that active repression by Runx1 occurs by blocking the elongation by RNAPII, which may contribute to CD4 silencing during T-cell development.

CD4 Antigens↗
PubMed2005

Interdependent recruitment of SAGA and Srb mediator by transcriptional activator Gcn4p.

Transcriptional activation by Gcn4p is enhanced by the coactivators SWI/SNF, SAGA, and Srb mediator, which stimulate recruitment of TATA binding protein (TBP) and polymerase II to target promoters. We show that wild-type recruitment of SAGA by Gcn4p is dependent on mediator but independent of SWI/SNF function at three different promoters. Recruitment of mediator is also independent of SWI/SNF but is enhanced by SAGA at a subset of Gcn4p target genes. Recruitment of all three coactivators to ARG1 is independent of the TATA element and preinitiation complex formation, whereas efficient recruitment of the general transcription factors requires the TATA box. We propose an activation pathway involving interdependent recruitment of SAGA and Srb mediator to the upstream activation sequence, enabling SWI/SNF recruitment and the binding of TBP and other general factors to the promoter. We also found that high-level recruitment of Tra1p and other SAGA subunits is independent of the Ada2p/Ada3p/Gcn5p histone acetyltransferase module but requires Spt3p in addition to subunits required for SAGA integrity. Thus, while Tra1p can bind directly to Gcn4p in vitro, it requires other SAGA subunits for efficient recruitment in vivo.

Acetyltransferases↗
PubMed2005

[Alleviation effect of exogenous Ca, P and N on the growth of Chinese fir seedlings under Al stress].

In this study, three month-old seedlings of Chinese fir (Cunninghamia laceolata) were grown in solution culture with 1 mmol x L(-1) Al at pH 4.0 for 80 days to evaluate the effects of varying concentrations of Ca, P, and NH4+-N or NO3(-)-N in solution on their growth. The morphological indexes (fresh weight, dry weight, shoot length, root length and relative elongation ratio) and physiological indexes (MDA content and POD activity) were submitted to statistical analysis and compared. The results indicated that the seedlings weight or shoot length had a significantly positive correlation with the molar ratio of solution Ca/Al. The MDA content and POD activity decreased with the increasing molar ratio of Ca/Al, and Ca/Al > or = 2.8 was the critical ratio. Similar to Ca/Al, high P/Al molar ratio also had an obvious effect on the growth of Chinese fir seedlings under Al stress, and P/Al > or = 4.5 was the critical ratio. The growth of Chinese fir seedlings was improved by increased NH4+-N supply, but the effect was less obvious than Ca and P. Solution NH4+-N/Al > or = 4.7 was the critical molar ratio. Solution NO3(-)-N could mitigate some adverse effects of Al on Chinese fir seedlings growth, but no regular effects were found with the change of solution NO3(-)-N/Al molar ratio.

Aluminum↗
PubMed2005

[Effects of exogenous nitric oxide donor on germination and activities of hydrolytic enzymes in wheat seed under osmotic stress].

Results in this paper showed that the effect of nitric oxide (NO) donor, sodium nitroprusside (SNP), which could promote the germination of wheat seeds under osmotic stress, was through enhancing imbibition using water content determination and imbibition analysis of wheat seed. SNP could also enhance amylase isozyme I activities, accelerate the liquefaction of endosperms, while have no effect on esterase. Moreover, SNP could strongly increase the sugars, such as the fructose, glucose and sucrose contents in wheat seeds during early germination (12 h) under normal conditions. When the seeds were treated with SNP with or without PTIO, an NO scavenger, and different exogenous sugars, i.e. fructose, glucose and sucrose, it was found that these sugars might activate amylase isozyme I activity mediated by the signal molecule NO to start the early stage of germination.

Amylases↗
PubMed2005

[Molecular analysis of the microbial communities of the Dagang Kongdian flooding bed oilfield].

Both PCR-TGGE (temperature gradient gel electrophoresis, TGGE) and 16S rRNA gene clone library construction were used to comparatively analyze the microbial communities of a water injection well (WW) and an oil well (OW) in Dagang oilfield. TGGE analysis of the PCR amplified 16S rDNA V3 region products showed great difference between these two microbial communities. Six major bands were detected in the TGGE profile of the WW sample, while only one predominant band in the OW sample was found. Two 16S rRNA gene clone libraries were also constructed, and 108 and 50 clones were selected from the WW and OW library respectively for amplified ribosomal DNA restriction analysis (ARDRA). 33 taxanomic operational units (OTUs) were found in the WW library with 6 major OTUs, while only 8 OTUs were found in the OW library with one OTU predominant. The results of TGGE and clone library profiling analysis both indicated that microbial community of the WW had higher diversity than the OW. Sequence analysis of the representative clone of each OTU showed that most bacteria of the WW were affiliated with alpha, beta, and gamma Proteobacteria and Actinobacteria, especially Rhodobacter (47%). Most bacteria of the OW were affiliated with alpha, beta, and gamma Proteobacteria, especially Pseudomonas (62%). Molecular analysis of the microbial diversity in oilfield provides foundation for better application of MEOR (Microbial Enhanced Oil Recovery).

Actinobacteria↗
PubMed2005

[Multicenter randomized controlled study on acupuncture-massage comprehensive program for treatment of cervical spondylosis of arterial type].

OBJECTIVE: To probe into clinical value of the acupuncture-massage comprehensive program for treatment of cervical spondylosis of arterial type (CSA). METHODS: By using three-center, single-blind, randomized, controlled method, the eligible subjects were randomly divided into an acupuncture-massage group, an acupuncture group, a massage group, 60 cases in each group. They were treated with acupuncture-massage comprehensive program, simple acupuncture and simple massage, respectively. And multiple-dimensional indexes were established to evaluate the therapeutic effect and safety. RESULTS: The baselines of the general data were no different among the 3 groups. The cured-markedly effective and the effective rate were 68.3% and 88.3% in the acupuncture-massage group, 51.7% and 75.0% in the acupuncture group, and 50.0% and 76.7% in the massage group, respectively, the acupuncture-massage group being better than the other 2 groups (P<0.05); after treatment, the total cumulative scores for symptoms in the 3 groups decreased significantly (all P<0.01), the acupuncture-massage group being superior to the other 2 groups (P<0.05); and the physical signs in the 3 groups improved significantly (P<0.01), with no significant differences among the 3 groups (P>0.05); the time inducing the effect in the acupuncture-massage group was shorter than that in the other 2 groups (P<0.05 or P<0.01); and no adverse effects were found in the 3 groups. CONCLUSION: This acupuncture-massage comprehensive therapy has a definite therapeutic effect on CSA with safety, and it is of superiority as compared with the simple acupuncture or the simple massage.

Acupuncture Points↗
PubMed2005

[Time-resolved optoacoustic technique and its applications to noninvasive monitoring of biological tissue].

Time-resolved optoacoustic technique offers a new ingredient in noninvasive monitoring of biological tissues. Due to the heterogeneous property of biotissue, different level of optical energy depositions generates different strength of the acoustic signal across the tissue. This makes it possible to probe the functional information tomographically inside the biological tissue. It becomes increasingly attractive as a hybrid non-invasive monitoring technique because it takes the advantages of high contrast feature delivered by the optical techniques and high penetration depth and resolution offered by the acoustical techniques. After a brief introduction of its theory, this paper reviews the state-of-the-art time-resolved optoacoustic methods that have been successfully applied in biomedicine, with a concentration on analytical monitoring and tomography.

Algorithms↗
PubMed2005

[Clinical observation on Ashi points Sihua needling method for treatment of acute soft tissue injury].

OBJECTIVE: To observe therapeutic effect of Ashi points Sihua needling method for treatment of acute soft tissue injury. METHODS: The patients were randomly divided into a treatment group (n = 105) and a control group (n = 108). They were treated respectively with Ashi points Sihua needling method and routine needling method. Their therapeutic effects and safety were assessed. RESULTS: The cured rate was 79.0% in the treatment group, better than 65.7% in the control group (P < 0.05); after treatment, the improvement degrees of pain, dysfunction and the total cumulative score in the treatment group were better than those in the control group (P < 0.05 or P < 0.01); the treatment group produced more quickly the effect with a shorter cured period as compared with the control group (P < 0.05 or P < 0.01). CONCLUSION: Ashi points Sihua needling method is safe and effective for acute soft tissue injury.

Acupuncture Points↗
PubMed2004

Transcriptional activity and substrate recognition of cyclin T2 from P-TEFb.

Transcriptional elongation by RNA polymerase II (RNAPII) is regulated by the positive transcription elongation factor b (P-TEFb), which contains Cdk9 and a C-type cyclin (CycT1, CycT2a, CycT2b, or CycK). Whereas their N-terminal cylin boxes are almost identical, the C-terminal sequences of CycT1 and CycT2 are divergent. Previously, a histidine-rich stretch in CycT1 was found to bind the CTD of RNAPII and direct the transcriptional activity of this P-TEFb complex when tethered artificially to DNA. The global repressor PIE-1 from C. elegans blocked its effects. In this study, C-terminal truncations of CycT2 past its histidine-rich stretch, to a leucine-rich region next to its cyclin boxes, still maintained appreciable transcriptional activity. Moreover, this domain bound RNAPII via its CTD and PIE-1 blocked its effects. Thus, CycT2 not only contains two domains that target RNAPII but this substrate recognition is necessary for its transcriptional activity via DNA.

Cell Line, Tumor↗
PubMed2004

Decreased levels of cytochrome P450 2E1-derived eicosanoids sensitize renal arteries to constrictor agonists in spontaneously hypertensive rats.

We compared renal interlobar arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) in terms of cytochrome P450 (CYP) 4A and CYP2E1 protein expression; levels of 20-HETE, 19-HETE, and 18-HETE; and responsiveness to phenylephrine in the absence and presence of N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS; 30 mumol/L), a CYP4A inhibitor. Relative to data in WKY, arteries of SHR exhibited diminished (P<0.05) CYP2E1 and levels of 19-HETE (66.7+/-6.0 versus 44.9+/-2.8 pmol/mg) and 18-HETE (13.8+/-1.6 versus 7.9+/-0.5 pmol/mg), whereas CYP4A and 20-HETE levels (99.3+/-9.1 versus 98.9+/-12.8 pmol/mg) were unchanged. Phenylephrine contracted vascular rings of SHR and WKY; the R(max) was similar in both strains, but SHR vessels were more sensitive as denoted by the lower (P<0.05) EC50 (0.28+/-0.07 versus 0.71+/-0.12 mumol/L). DDMS decreased 20-HETE and, to a lesser extent, 19-HETE, while increasing (P<0.05) the EC50 for phenylephrine by 475% and 54% in vessels of SHR and WKY, respectively. The desensitizing effect of DDMS was reversed by 20-HETE. Notably, the minimal concentration of 20-HETE that decreased the EC50 for phenylephrine in DDMS-treated vessels was smaller in SHR (0.1 micromol/L) than WKY (10 micromol/L), and the sensitizing effect of 20-HETE was blunted (P<0.05) by the (R) stereoisomers of 19-HETE and 18-HETE. We conclude that the increased sensitivity to phenylephrine in arteries of SHR is attributable to a vasoregulatory imbalance produced by a deficit in vascular CYP2E1-derived products, most likely 19(R)-HETE and 18(R)-HETE, which condition amplification of the sensitizing action of 20-HETE.

Amides↗
PubMed2004

Effects of glucagon-like peptide-1 on endothelial function in type 2 diabetes patients with stable coronary artery disease.

GLP-1 stimulates insulin secretion, suppresses glucagon secretion, delays gastric emptying, and inhibits small bowel motility, all actions contributing to the anti-diabetogenic peptide effect. Endothelial dysfunction is strongly associated with insulin resistance and type 2 diabetes mellitus and may cause the angiopathy typifying this debilitating disease. Therefore, interventions affecting both endothelial dysfunction and insulin resistance may prove useful in improving survival in type 2 diabetes patients. We investigated GLP-1's effect on endothelial function and insulin sensitivity (S(I)) in two groups: 1) 12 type 2 diabetes patients with stable coronary artery disease and 2) 10 healthy subjects with normal endothelial function and S(I). Subjects underwent infusion of recombinant GLP-1 or saline in a random crossover study. Endothelial function was measured by postischemic FMD of brachial artery, using ultrasonography. S(I) [in (10(-4) dl.kg(-1).min(-1))/(muU/ml)] was measured by hyperinsulinemic isoglycemic clamp technique. In type 2 diabetic subjects, GLP-1 infusion significantly increased relative changes in brachial artery diameter from baseline FMD(%) (3.1 +/- 0.6 vs. 6.6 +/- 1.0%, P < 0.05), with no significant effects on S(I) (4.5 +/- 0.8 vs. 5.2 +/- 0.9, P = NS). In healthy subjects, GLP-1 infusion affected neither FMD(%) (11.9 +/- 0.9 vs. 10.3 +/- 1.0%, P = NS) nor S(I) (14.8 +/- 1.8 vs. 11.6 +/- 2.0, P = NS). We conclude that GLP-1 improves endothelial dysfunction but not insulin resistance in type 2 diabetic patients with coronary heart disease. This beneficial vascular effect of GLP-1 adds yet another salutary property of the peptide useful in diabetes treatment.

Adult↗
PubMed2004

Transfection and functional expression of CYP4A1 and CYP4A2 using bicistronic vectors in vascular cells and tissues.

20-hydroxyeicosatetraenoic acid (20-HETE), a CYP4A-derived arachidonic acid metabolite, is a potent vasoconstrictor and a modulator of vascular reactivity. We have shown that CYP4A1 and CYP4A2 are the major CYP4A isoforms expressed in the rat renal microcirculation. In the present study, we constructed two bicistronic vectors, pIRES2-EGFP-4A1 and pIRES2-EGFP-4A2, and examined their functional efficacy in COS-1 and vascular smooth muscle (A7r5) cells and in microdissected rat interlobar arteries. Immunocytochemistry coupled with fluorescence microscopy of pIRES2-EGFP-4A1- or pIRES2-EGFP-4A2-transfected COS-1 and A7r5 cells indicated that both enhanced green fluorescence protein (EGFP) and CYP4A1/4A2 were expressed in 80 to 90% of the cells. Western blot analysis showed a 3- to 5-fold increase of CYP4A1 and CYP4A2 proteins in pIRES2-EGFP-4A1- and pIRES2-EGFP-4A2-transfected cells as compared with control pIRES2-transfected cells. Cells transfected with pIRES2-EGFP-4A1 and pIRES2-EGFP-4A2 catalyzed arachidonic acid omega-hydroxylation to 20-HETE at rates of 0.85 +/- 0.29 and 0.27 +/- 0.04 nmol/10(7) cells/h, respectively. Transfection of interlobar arteries with either plasmid yielded EGFP immunofluorescence that was localized to the intima, media, and adventitia. Arteries transfected with pIRES2-EGFP-4A1 and pIRES2-EGFP-4A2 showed increased vasoreactivity displaying EC50 to phenylephrine of 0.24 +/- 0.07 and 0.11 +/- 0.03 microM, respectively, as compared with arteries transfected with pIRES2-EGFP (1.11 +/- 0.21 microM; n=6, p <0.05). The increased vasoreactivity to phenylephrine was inhibited by N-methylsulfonyl-12,12-dibromododec-11-enamide, an inhibitor of CYP4A-catalyzed reactions, suggesting that a product of CYP4A1 and CYP4A2 catalytic activity contributed to the increased constrictor responsiveness. Removal of the endothelium did not prevent the sensitization to phenylephrine in vessels transfected with the plasmid containing the CYP4A1 cDNA, suggesting that the CYP4A product responsible for the sensitizing effect, presumably 20-HETE, is not of endothelial cell origin.

Adrenergic alpha-Agonists↗
PubMed2004

SNARE assembly and membrane fusion, a kinetic analysis.

SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) assembly may promote intracellular membrane fusion, an essential process for vesicular transport in cells. Core complex formation between vesicle-associated SNARE and target membrane SNARE perhaps drives the merging of two membranes into a single bilayer. Using spin-labeling EPR, trans-SNARE complex formation was monitored "locally" at four different core locations of recombinant yeast SNAREs, which are individually reconstituted into phospholipid vesicles. The results indicate that the time scales of core formation are virtually the same at all four locations throughout the core region, indicating the possibility of a single step core assembly, which appears to be somewhat different from what has been postulated by the "zipper" model. The EPR data were then compared with the kinetics of the lipid mixing measured with the fluorescence assay. The analysis suggests that SNARE core assembly occurs on a much faster time scale than the lipid mixing, providing a new insight into the timing of individual events in SNARE-induced membrane fusion.

Cell Membrane↗
PubMed2004

Vascular CO counterbalances the sensitizing influence of 20-HETE on agonist-induced vasoconstriction.

We examined the influence of interactions between CO and 20-hydroxyeicosatetraenoic acid (20-HETE) on vascular reactivity to phenylephrine and vasopressin. Renal interlobar arteries incubated in Krebs buffer released CO at a rate that is decreased (from 125.0+/-15.2 to 46.3+/-8.8 pmol/mg protein per hour, P<0.05) by the heme oxygenase inhibitor chromium mesoporphyrin (CrMP; 30 micromol/L). The level of 20-HETE in vessels was not affected by CrMP (74.3+/-6.1 versus 72.5+/-16.2 pmol/mg protein), but was decreased (P<0.05) by CO (1 micromol/L; 33.2+/-7.9 pmol/mg protein) or the cytochrome P450-4A inhibitor N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS; 30 micromol/L; 11.4+/-3.3 pmol/mg protein). Phenylephrine elicited development of isometric tension in vascular rings mounted on a wire-myograph (EC(50), 0.29+/-0.02 micromol/L; R(max), 3.78+/-0.19 mN/mm). The sensitivity to phenylephrine was decreased (P<0.05) by CO (1 micromol/L; EC(50), 0.60+/-0.04 micromol/L) or DDMS (EC(50), 0.71+/-0.12 micromol/L) and increased (P<0.05) by 20-HETE (10 micromol/L; EC(50), 0.08+/-0.02 micromol/L) or CrMP (EC(50), 0.11+/-0.02 micromol/L). Notably, neither CO nor CrMP changed the sensitivity to phenylephrine in vessels treated with DDMS. Refractoriness to CO and CrMP in such a setting was eliminated by inclusion of 20-HETE (1 micromol/L) in the bathing buffer. The aforementioned interventions affected the vascular reactivity to vasopressin in a similar manner. These data indicate that the reactivity of renal arteries to phenylephrine and vasopressin is reciprocally influenced by CO and 20-HETE of vascular origin and that CO desensitizes the vascular smooth muscle to constrictor agonists by interfering with the sensitizing influence of 20-HETE.

Adrenergic Agonists↗