Biomedical subjects

Hao Huang

Publications and source records attributed to Hao Huang.

31 records · Page 2Linked to original sources

PubMed2004

Inhibition of osteoclast differentiation and bone resorption by tanshinone IIA isolated from Salvia miltiorrhiza Bunge.

Osteoclasts, multinuclear cells specialized for bone resorption, differentiate from the monocyte/macrophage lineage of hematopoietic cells. Intervention in osteoclast differentiation is considered an effective therapeutic approach to the treatment of bone diseases involving osteoclasts. In this study, we found that tanshinone IIA, originating from Salvia miltiorrhiza Bunge, inhibited the differentiation of osteoclasts. Addition of tanshinone IIA to the osteoclast precursor culture caused a significant decrease in the level of calcitonin receptor, c-Src, and integrin beta3 mRNA, which are normally upregulated during the osteoclast differentiation dependent on RANKL (receptor activator of nuclear factor kappa B ligand). RANKL activated the ERK, Akt, and NF-kappaB signal transduction pathways in osteoclast precursor cells, and tanshinone IIA suppressed this activation. Tanshinone IIA also inhibited the bone resorptive activity of differentiated osteoclasts, which was accompanied with the disruption of the actin ring. Thus, tanshinone IIA has the potential to ameliorate bone-resorption diseases in vivo by reducing both the number and activity of osteoclasts.

Abietanes↗

PubMed2004

Analysis of noise effects on DTI-based tractography using the brute-force and multi-ROI approach.

Diffusion tensor tractography based on line propagation is a promising and widely used technique, but it is known to be sensitive to noise and the size and location of the seed regions of interest (ROIs). The effects of these parameters on the tractography results were analyzed quantitatively using high-resolution diffusion tensor imaging (DTI) with a high signal-to-noise ratio (SNR) on a fixed mouse brain. The anterior commissure (AC), as judged from a T2-weighted image, was used as an anatomical reference within which the tracts could be located. Monte Carlo simulation was performed by adding Gaussian noise to the time domain data and repeating the tractography. Deviations of the tracking results were measured as a function of SNR. Such noise effects were evaluated for a simple one-ROI approach and a combined two-ROI and brute-force (BF) approach. The influence of ROI size and location for the two-ROI + BF approach was also analyzed. The results confirmed the hypothesis that one can increase the validity of DTI-based tractography by adopting the BF and multi-ROI approach, with respect to the simple one-ROI approach.

Animals↗

PubMed2004

[Novel molecular marker systems--SRAP and TRAP and their application].

SRAP and TRAP are two kinds of newly developed molecular marker systems with the advantages of simplicity, high throughput, numerous co-dominant makers, highly reproducibility and ready to sequence, especially preferential targeting ORFs. The principle and protocol of SRAP and TRAP, which were developed in Brassica and Helianthus crops firstly, are introduced in the paper. Primer design is a key step for SRAP and TRAP, and some F-and R-primers were developed. Unlike SRAP technique, the TRAP requires cDNA or EST sequence information for fixed primer development. The annealing temperature is 35 degrees in the first 5 cycles and 50 degrees in the subsequent 30~35 cycles. The amplicons can be separated by polyacrylamide or agarose gel, and detected by autoradiography, silver or EB staining. SRAP and TRAP are applied in germplasm genetic diversity analysis, genetic map including transcriptome map construction, important trait gene tagging and gene cloning in many crops.

Acid Phosphatase↗

PubMed2004

[Study on the identification of standard and false BanXia by two-dimensional infrared correlation spectroscopy].

Standard BanXia (Pinellia temata (Thumb.) Breit) and false Shui BanXia (Typhonium flagelliforme (Lodd.) Blume) were identified fast and nondestructively by Fourier Transform Infrared Spectroscopy (FTIR) combined with two-dimensional correlation spectroscopy (2D) in this paper. The two kinds of BanXia wree similar to each other in one-dimensional IR spectra but quite different in 2D FTIR spectra. In the range between 1 220 cm(-1) and 1700 cm(-1), one strong autopeak was aroused by BanXia around 1410 cm(-1) in synchronous spectrum, whereas three autopeaks not only at 1460 cm(-1) but also at 1540 cm(-1) and 1680 cm(-1) aroused by Shui BanXia. Also in the range between 940 cm(-1) and 1220 cm(-1), three autopeaks were shown at 980, 1080 and 1150 cm(-1) in synchronous spectrum of BanXia, but only two autopeaks at 1080 and 1150 cm(-1) in synchronous spectrum of Shui BanXia. It is proved that the 2D FTIR could serve in distinguishing standard and false medicinal herbs due to its unique advantages such as enhanced resolution and increased identification ability. Therefore, the rapidity and accuracy of 2D FTIR spectroscopy make it a powerful and new approach to evaluating the medicinal herbs.

Binding Sites↗

PubMed2003

Complexes of RecA with LexA and RecX differentiate between active and inactive RecA nucleoprotein filaments.

The bacterial RecA protein has been the dominant model system for understanding homologous genetic recombination. Although a crystal structure of RecA was solved ten years ago, we still do not have a detailed understanding of how the helical filament formed by RecA on DNA catalyzes the recognition of homology and the exchange of strands between two DNA molecules. Recent structural and spectroscopic studies have suggested that subunits in the helical filament formed in the RecA crystal are rotated when compared to the active RecA-ATP-DNA filament. We examine RecA-DNA-ATP filaments complexed with LexA and RecX to shed more light on the active RecA filament. The LexA repressor and RecX, an inhibitor of RecA, both bind within the deep helical groove of the RecA filament. Residues on RecA that interact with LexA cannot be explained by the crystal filament, but can be properly positioned in an existing model for the active filament. We show that the strand exchange activity of RecA, which can be inhibited when RecX is present at very low stoichiometry, is due to RecX forming a block across the deep helical groove of the RecA filament, where strand exchange occurs. It has previously been shown that changes in the nucleotide bound to RecA are associated with large motions of RecA's C-terminal domain. Since RecX binds from the C-terminal domain of one subunit to the nucleotide-binding core of another subunit, a stabilization of RecA's C-terminal domain by RecX can likely explain the inhibition of RecA's ATPase activity by RecX.

Bacterial Proteins↗

PubMed2003

Neuroprotective effects of Buyang Huanwu Decoction on neuronal injury in hippocampus after transient forebrain ischemia in rats.

Buyang Huanwu Decoction (BYHWD), a traditional Chinese medicine, has been developed as a drug to be used for treatment of stroke for hundreds of years. However, the underlying mechanisms remain unknown. In the present study, the effects of BYHWD on delayed neuronal death of hippocampus after transient forebrain ischemia were examined in rats. Transient forebrain ischemia in a duration of 15 min was induced with the four-vessel occlusion method. BYHWD (per 6.65 g/kg) was given orally to rats twice each day for 7 days before ischemia. In BYHWD-pretreated rats, the neuronal injury in the hippocampal CA1 region was significantly less than that of controls. Oral administration of BYHWD also markedly attenuated the number of TUNEL-positive neurons and suppressed the expression of caspase-3p20, a product of catalytically active caspase-3, in the CA1 region. Our results suggest that an inhibition of caspase-3 and apoptosis by BYHWD may partially account for its neuroprotection against ischemic injury in the hippocampal CA1 region.

Animals↗

PubMed2003

Three-dimensional anatomical characterization of the developing mouse brain by diffusion tensor microimaging.

Investigation of three-dimensional (3D) morphometry of developing brains has been hindered by a lack of imaging modalities that can monitor the 3D evolution of various anatomical structures without sectioning and staining processes. In this study, we combined magnetic resonance microimaging and diffusion tensor imaging techniques to accomplish such visualization. The application of this approach to developing mouse embryos revealed that it could clearly delineate early critical structures such as neuroepithelium, cortical plate, and various axonal structures, and follow their developmental evolution. The technique was applied to the study of the Netrin-1 mutant, allowing verification of its anatomical phenotype.

Animals↗

PubMed2003

[Novel application of FTIR in medical herb chemotaxonomy].

Typical medical plants in Araliaceae, Campanulaceae, Magnoliaceae, Lauraceae, Leguminosae, Berberidaceae, Pteridophyta, etc. were studied with FTIR for the first time, and the similarities and differences within each familiar were also pointed out. Furthermore the differences in spectra of samples from different parts or collected at different time on the same plant were also discussed. The characteristic radicals of the mainly effective components in plants were identified, and the primary peaks were deciphered. It was considered that FTIR could become a rapid, reliable, impersonal and effective method in chemotaxonomy as a supplement of morphologic plant taxonomy.

Araliaceae↗

PubMed2003

[Screening and identification of proteins interacting with p38 MAP kinase via T7 phage-display screening system].

OBJECTIVE: To screen and identify proteins that interact with p38 mitogen-activated protein (MAP) kinases by means of T7 phage-display screening system. METHOD: His-tagged fusion protein of p38 MAP kinase was used to coat a 96-well ELISA plate and Ni-NTA resin, which served as the media for screening human lung and liver T7 phage cDNA libraries. RESULTS: After 4 rounds of biopanning, 86 independent plaques were selected and processed by EDTA. The inserted gene fragments from these plaques were amplified by PCR, the products purified by a gel recovery method. The sequences of the insertions were identified and analyzed with BLAST program in GenBank. Forty-six clones were found to encode proteins. CONCLUSION: T7 phage-display screening system is convenient, rapid and effective for screening the P38 MAP kinase-binding proteins.

Bacteriophage T7↗

PubMed2002

Involvement of actin cytoskeleton in modulation of Ca(2+)-activated K(+) channels from rat hippocampal CA1 pyramidal neurons.

Using inside-out configuration of patch clamp techniques, actin cytoskeleton modulation of large conductance calcium-activated potassium (BK(Ca)) channels was studied in hippocampal CA1 pyramidal neurons from adult rat. Disruption of actin filament after brief treatment with cytochalasin D (CD) markedly decreased activity of BK(Ca) channels and this inhibitory action persisted even after CD washout. This CD-produced decrease in BK(Ca) channel activity was characterized by a shortened open lifetime and reduced opening frequency. Disruption of actin filament with another toxin cytochalasin B also exerted similar effects as CD. Phalloidin, the actin filament stabilizer, had no significant effect on BK(Ca) channel activity, while pre-treatment with phalloidin could prevent the CD-induced inhibitory effect on channel activity. The present study demonstrates that disruption of actin cytoskeleton can inhibit BK(Ca) channel activity, suggesting that BK(Ca) channels in rat hippocampal CA1 pyramidal neurons may be directly modulated by dynamic assembly and disassembly of submembranous actin cytoskeleton.

Actins↗

PubMed2002

ATP modulation of large conductance Ca(2+)-activated K(+) channels via a functionally associated protein kinase A in CA1 pyramidal neurons from rat hippocampus.

Using inside-out configuration of patch clamp techniques, ATP modulation of BK(Ca) channels was studied in hippocampal CA1 pyramidal neurons of adult rat. Intracellular ATP application markedly increased BK(Ca) channel activity, and this ATP-produced increase in BK(Ca) channel activity was characterized by a higher opening frequency with no changes in channel open times. In the presence of specific inhibitor against protein kinase A, H-89, ATP did not induce any increase in the channel activity. Furthermore, adding H-89 after addition of ATP reversed the modulation produced by ATP. In contrast, protein kinase C inhibitor chelerythrine exerted no apparent effects on ATP-induced channel activation. The present study suggests that BK(Ca) channels from hippocampal CA1 pyramidal neurons could be modulated by ATP via a functionally associated protein kinase A-like protein.

Adenosine Triphosphate↗

PubMed2002

Transient forebrain ischemia induces persistent hyperactivity of large conductance Ca2+-activated potassium channels via oxidation modulation in rat hippocampal CA1 pyramidal neurons.

The present study examined temporal changes in activity of large conductance, Ca2+-activated potassium (BKCa) channels in postischemic CA1 pyramidal neurons at 2, 6, 24 and 48 h after reperfusion. These changes in activity and possible cellular mechanisms were examined using the inside--out configuration of patch clamp. The unitary conductance of postischemic BKCa channels increased transiently to 119% of the control at 2 h after reperfusion, and recovered to the control level thereafter. A persistent increase in [Ca2+]i sensitivity of BKCa channels was observed in postischemic CA1 neurons with the maximal sensitivity to [Ca2+]i at 6 h after reperfusion while channel voltage- dependence showed no obvious changes. Kinetic analyses showed that the postischemic enhancement of BKCa channel activity was due to longer open times and shorter closed times as there was no significant changes in opening frequency after ischemia. Glutathione disulphide markedly increased BKCa channel activity in normal CA1 neurons, while reducing glutathione caused a decrease in BKCa channel activity by reducing the sensitivity of this channel to [Ca2+]i in postischemic CA1 neurons. Similar modulatory effects on postischemic BKCa channels were also observed with another redox couple, DTNB and DTT, suggesting an oxidation modulation of BKCa channel function after ischemia. The present results indicate that a persistent enhancement in activity of BKCa channels, probably via oxidation of channels, in postischemic CA1 pyramidal neurons may account for the decrease in neuronal excitability and increase in fAHP after ischemia. The ischemia-induced augmentation in BKCa channel activity may be also associated with the postischemic neuronal injury.

Animals↗

PubMedDate not supplied

Assessment of experimental bond dissociation energies using composite ab initio methods and evaluation of the performances of density functional methods in the calculation of bond dissociation energies.

Composite ab initio CBS-Q and G3 methods were used to calculate the bond dissociation energies (BDEs) of over 200 compounds listed in CRC Handbook of Chemistry and Physics (2002 ed.). It was found that these two methods agree with each other excellently in the calculation of BDEs, and they can predict BDEs within 10 kJ/mol of the experimental values. Using these two methods, it was found that among the examined compounds 161 experimental BDEs are valid because the standard deviation between the experimental and theoretical values for them is only 8.6 kJ/mol. Nevertheless, 40 BDEs listed in the Handbook may be highly inaccurate as the experimental and theoretical values for them differ by over 20 kJ/mol. Furthermore, 11 BDEs listed in the Handbook may be seriously flawed as the experimental and theoretical values for them differ by over 40 kJ/mol. Using the 161 cautiously validated experimental BDEs, we then assessed the performances of the standard density functional (DFT) methods including B3LYP, B3P86, B3PW91, and BH&HLYP in the calculation of BDEs. It was found that the BH&HLYP method performed poorly for the BDE calculations. B3LYP, B3P86, and B3PW91, however, performed reasonably well for the calculation of BDEs with standard deviations of about 12.1-18.0 kJ/mol. Nonetheless, all the DFT methods underestimated the BDEs by 4-17 kJ/mol in average. Sometimes, the underestimation by the DFT methods could be as high as 40-60 kJ/mol. Therefore, the DFT methods were more reliable for relative BDE calculations than for absolute BDE calculations. Finally, it was observed that the basis set effects on the BDEs calculated by the DFT methods were usually small except for the heteroatom-hydrogen BDEs.

Journal Article↗