Biomedical subjects

H Zhang

Publications and source records attributed to H Zhang.

At least 37 records · Page 2Linked to original sources

PubMed2006

Impact of oral azithromycin on recurrence of trachomatous trichiasis in Nepal over 1 year.

BACKGROUND: Recently, a significant association between Chlamydia trachomatis infection and postoperative trachomatous trichiasis (TT) recurrence was shown. The current study evaluated whether azithromycin treatment at the time of surgery could reduce recurrence. METHODS: As part of Nepal's national trachoma control programme, patients received azithromycin (53 patients) or placebo (56 patients) at surgery. Conjunctivae were graded for trachoma and swabbed to detect chlamydiae preoperatively and postoperatively up to 12 months. Logistic regression was performed for associations of treatment option with recurrence, infection, and active trachoma (by eye and by patient). RESULTS: TT recurrence was 28.9% at 12 months. Recurrence was significantly lower for those with major TT at baseline in the azithromycin group at 12 months (p = 0.03); incident recurrence was also significantly lower at 6 months (OR, 0.056; 95% CI, 0 to 0.423; p = 0.004). There was a trend for increased recurrence among those with minor TT at baseline and for reduction of active trachoma and infection in the azithromycin group but not the placebo group. CONCLUSION: These data suggest that azithromycin treatment at the time of surgery may be warranted for patients with major TT. However, treatment should be investigated further for minor TT, for efficacy at subsequent time intervals and in other trachoma endemic settings.

Administration, Oral↗

PubMed2006

Involvement of programmed cell death 4 in transforming growth factor-beta1-induced apoptosis in human hepatocellular carcinoma.

The programmed cell death 4 (PDCD4) gene was originally identified as a tumor-related gene in humans and acts as a tumor-suppressor in mouse epidermal carcinoma cells. However, its function and regulatory mechanisms of expression in human cancer remain to be elucidated. We therefore investigated the expression of PDCD4 in human hepatocellular carcinoma (HCC) and the role of PDCD4 in human HCC cells. Downregulation of PDCD4 protein was observed in all HCC tissues tested compared with corresponding noncancerous liver, as revealed by Western blotting or immunohistochemical staining. Human HCC cell line, Huh7, transfected with PDCD4 cDNA showed nuclear fragmentation and DNA laddering characteristic of apoptotic cells associated with mitochondrial changes and caspase activation. Transforming growth factor-beta1 (TGF-beta1) treatment of Huh7 cells resulted in increased PDCD4 expression and occurrence of apoptosis, also concomitant with mitochondrial events and caspase activation. Transfection of Smad7, a known antagonist to TGF-beta1 signaling, protected cells from TGF-beta1-mediated apoptosis and suppressed TGF-beta1-induced PDCD4 expression. Moreover, antisense PDCD4 transfectants were resistant to apoptosis induced by TGF-beta1. In conclusion, these data suggest that PDCD4 is a proapoptotic molecule involved in TGF-beta1-induced apoptosis in human HCC cells, and a possible tumor suppressor in hepatocarcinogenesis.

Aged↗

PubMed2006

Centrosomal proteins Nde1 and Su48 form a complex regulated by phosphorylation.

The centrosome modulates spindle formation and plays a critical role in guiding proper segregation of chromosomes during cell division. Centrosome aberrations, frequently seen in human tumors, may cause abnormal chromosome segregation and contribute to malignant transformation. To explore the components of the centrosomes, we previously identified a novel centrosomal protein called Su48. To further characterize the Su48-containing protein ensemble in the centrosome, we performed yeast two-hybrid screens and isolated a number of Su48-interacting molecules, including the centrosomal protein Nde1. Here, we demonstrate that Su48 can associate with Nde1. Moreover, we found that Nde1 is subjected to phosphorylation in vivo. In particular, we identified six putative Cdc2 phosphorylation sites in Nde1 and found that alteration of these sites diminishes phosphorylation by Cdc2 in vitro and affects the stability of Su48-Nde1 interactions and the centrosomal localization of Nde1. Ablation of Nde1 by gene specific small interfering RNA causes mitotic delay and cell death, coupled with a modest decrease in the incidence of the cells that harbor excessive centrosomes. Collectively, our findings indicate that Nde1 can form a protein complex with Su48 in the centrosome and plays an important role for successful mitosis.

Carrier Proteins↗

PubMed2006

Complete nucleotide sequences of three dsRNA segments from Raphanus sativus-root cv. Yidianhong [corrected] with leaf yellow edge symptoms.

The two minor dsRNA bands, previously detected in symptomatic leaves of Raphanus sativus-root cv. Yidianhong [corrected] were subjected to further analysis. cDNA cloning and sequencing revealed that the smaller of the two dsRNA bands is actually a doublet consisting of two co-migrating dsRNA segments and the resulting three segments were designated as RasR 3, RasR 4, and RasR 5. RasR 3 was 1717 bp in length and potentially encoded a protein of about 55.3 kDa, containing all of the six conserved motifs shared by the RNA dependent RNA polymerases of members of the family Partitiviridae. RasR 4 and RasR 5, which co-migrated in the 5% polyacrylamide gel, were 1521 and 1485 bp in length and each encoded a putative protein of unknown function. Their molecular masses, as calculated from the deduced amino acid, were 38.2 and 38.8 kDa, respectively. The 5' UTRs of all three segments shared regions of high sequence similarities, but were distinct from those of the RasR 1 and RasR 2. Taken together, these results along with those described in the previous report, suggest that more than one partitivirus was co-infecting radish leaves.

5' Untranslated Regions↗

PubMed2006

Arsenic trioxide reduces the invasive and metastatic properties of nasopharyngeal carcinoma cells in vitro.

Nasopharyngeal carcinoma (NPC) is notorious for the metastases, which are in close association with Epstein-Barr virus-encoded latent membrane protein 1 (LMP1). Arsenic trioxide (As2O3) has been shown to induce apoptosis and differentiation in NPC xenografts. Then, can it repress the cancer cells' metastasis potential? To elucidate this issue, the present study was performed. LMP1-negative cell line HNE1 and LMP1-positive cell line HNE1-LMP1 were used as in vitro model. Cells (1 x 10(5)/mL) were cultured with or without 3 microM As2O3 for 48 h. Then the survival cells were collected to investigate their potential of colony formation, attachment, invasion, and migration. Both confocal immunofluorescence staining and Western blot were used to detect the changes of LMP1 expression. The changes of MMP-9 were examined by RT-PCR assay and Western blot. The results were as follow: i) the colony formation inhibition rate (75.41 +/- 3.9% in HNE1-LMP1 cells vs 37.89 +/- 4.9% in HNE1 cells), the rate of attachment (HNE1-LMP1 vs HNE1: 56.40 +/- 3.5 vs 65.87 +/- 5.9%), the invasion inhibitory rate (HNE1-LMP1 vs HNE1: 56.50 +/- 3.7 and 27.91 +/- 2.1%), and the migration inhibitory rate (HNE1-LMP1 vs HNE1: 48.70 +/- 3.9 vs 29.19 +/- 6.27%) were all significantly different between the two cell lines (P < 0.01). ii) LMP1 was down-regulated in As2O3-treated HNE1-LMP1 cells. iii) The reduction of MMP-9 was found in As2O3-treated groups, more evident in HNE1-LMP1 cells. Thus, we conclude that As2O3 can reduce metastasis potential of NPC cells, involving inhibition of MMP-9 expression. LMP1 were also reduced in this process and seemed to enhance anti-metastasis activity of As2O3.

Antineoplastic Agents↗

PubMed2006

Efficient production of laccases by Trametes sp. AH28-2 in cocultivation with a Trichoderma strain.

A biocontrol fungus isolated from rotting wood was identified as a Trichoderma strain (named as Trichoderma sp. ZH1) by internal transcribed spacer (ITS) sequences of rRNA genes. The laccase yield of Trametes sp. AH28-2 in cocultivation with Trichoderma sp. ZH1 reached 6,210 U l(-1), approximately identical to those induced by toxic aromatic inducers. Cocultures maintained 60-70 % of their highest laccase activity obtained at 5 days after inoculation of the biocontrol fungus, at least for 20 days. Furthermore, a novel laccase isozyme (LacC) was obtained through the fungal interactions. The molecular weight of LacC is about 64 kDa, and its isoelectric point is 6.6. The temperature and pH optimum for LacC to oxidize guaiacol are 55 degrees C and 5.0, respectively. LacC is stable both at 60 degrees C and pH 4.0-8.0. Furthermore, the K (m) values of LacC for various substrates were also determined. Our work demonstrates a safe strategy for the production of industrial laccases, instead of the traditional method of chemical induction.

DNA, Fungal↗

PubMed2006

p78/MCRS1 forms a complex with centrosomal protein Nde1 and is essential for cell viability.

The centrosome, an organelle that functions as the major microtubule-organizing center, plays an essential role in the formation of the mitotic spindle and guiding accurate chromosome segregation. Centrosome aberrations are frequently associated with various forms of human cancers and it is thought that defects in this organelle contribute to genomic instability and malignant transformation. We recently identified and characterized a centrosome-localized protein complex that is comprised of Su48 and Nde1. Disruption of the normal function of these proteins leads to abnormal cell division. To extend our understanding of how this protein complex operates, we sought to identify Nde1-interacting molecules by the yeast two-hybrid screening method. Here, we demonstrate that both Nde1 and Su48 can associate with p78/MCRS1, a protein implicated in cancer development. We found that, whereas the majority of p78 localizes to the nucleus as reported in earlier studies, a fraction of the p78 protein can be detected in the centrosome. Moreover, we determined that a region containing the forkhead-associated domain of p78 is involved in association with Nde1 and Su48, as well as in centrosomal localization. We also provide evidence that the association between p78 and Nde1 is regulated by phosphorylation on Nde1. Furthermore, abrogation of the endogenous p78 function by small interfering RNA knockdown causes cell death and a modest delay in mitosis. These results indicate that a subset of the p78 proteins comprises a component of the centrosome and that p78 is essential for cell viability.

Carrier Proteins↗

PubMed2006

Fascin is a potential biomarker for early-stage oesophageal squamous cell carcinoma.

BACKGROUND: Fascin, an actin-binding protein, is usually expressed at a low level in normal epithelium, but is markedly up regulated in several types of carcinomas. Reports on fascin expression in oesophageal squamous cell carcinoma (ESCC) and precancerous lesions remain rare. AIM: To show the roles of fascin in the progression from normal epithelium to invasive ESCC. METHODS: Fascin expression in 102 sections embedded in paraffin wax, including samples of normal mucosa (n = 20), dysplasia (n = 10), ESCC (n = 62) and special sections (n = 10) of a full-length mucosa layer from the distant margin to the cancer focus of the excised oesophagus, and 49 fresh specimens of ESCC was analysed by immunohistochemistry, western blot and real-time reverse transcription-polymerase chain reaction. Fascin expression in ESCC cell lines was also investigated. RESULTS: In the immunohistochemical study, the positive rate of fascin was significantly higher in the tumour tissue than in the normal epithelium (p = 0.020), but no significant difference was shown between ESCC and dysplasia (p = 1.000). Immunostaining for fascin was only apparent in the basal layer of the normal epithelium. However, in the dysplasia, positive staining was observed in most of the heterogeneous cells from the basal layer to the granular layer of the epithelium. Fascin expression was seen to increase progressively from the normal epithelium to invasive ESCC. Up regulation of fascin was observed in 87.76% (43/49) and 77.55% (38/49) of the specimens, respectively, using western blot and real-time reverse transcription-polymerase chain reaction assays; 80% (4/5) of ESCC cell lines also expressed fascin at a high level. Furthermore, overexpression of fascin was markedly correlated with cell proliferation and lymph node metastasis. CONCLUSIONS: These findings suggested that fascin was associated with the transformation and development of ESCC and implicated the potential of fascin as a novel biomarker that would allow the tumour to be identified at an early stage in high-risk individuals.

Adult↗

PubMed2006

A theoretical investigation of hyperpolarizability for small Ga(n)As(m) (n + m = 4-10) clusters.

In this paper, the second and third order polarizabilities of small Ga(n)As(m) (n + m=4-10) clusters are systematically investigated using the time dependent density functional theory (TDDFT)6-311+G* combined with the sum-over-states method (SOSTDDFT6-311+G*). For the static second order polarizabilities, the two-level term (beta(vec.2)) makes a significant contribution to the beta(vec) for all considered Ga(n)As(m) clusters except for the Ga3As4 cluster. And, for the static third order polarizabilities, the positive channel (gamma(II)) makes a larger contribution to gamma(tot) than the negative channel (gamma(I)). Similar to the cubic GaAs bulk materials, the small Ga(n)As(m) cluster assembled materials exhibit large second order (1 x 10(-6) esu) and third order susceptibilities (5 x 10(-11) esu). The dynamic behavior of beta(-2omega; omega, omega) and gamma(-3omega; omega, omega, omega) show that the small Ga(n)As(m) cluster will be a good candidate of nonlinear optical materials due to the avoidance of linear resonance photoabsorption.

Journal Article↗

PubMed2006

Direct observation of electron-to-hole energy transfer in CdSe quantum dots.

We independently determine the subpicosecond cooling rates for holes and electrons in CdSe quantum dots. Time-resolved luminescence and terahertz spectroscopy reveal that the rate of hole cooling, following photoexcitation of the quantum dots, depends critically on the electron excess energy. This constitutes the first direct, quantitative measurement of electron-to-hole energy transfer, the hypothesis behind the Auger cooling mechanism proposed in quantum dots, which is found to occur on a 1 +/- 0.15 ps time scale.

Journal Article↗

PubMed2006

Creatine in Huntington disease is safe, tolerable, bioavailable in brain and reduces serum 8OH2'dG.

In a randomized, double-blind, placebo-controlled study in 64 subjects with Huntington disease (HD), 8 g/day of creatine administered for 16 weeks was well tolerated and safe. Serum and brain creatine concentrations increased in the creatine-treated group and returned to baseline after washout. Serum 8-hydroxy-2'-deoxyguanosine (8OH2'dG) levels, an indicator of oxidative injury to DNA, were markedly elevated in HD and reduced by creatine treatment.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2006

Structure model for the tau(mu) phase in Al-Cr-Si alloys deduced from the lambda phase by the strong-reflections approach.

There are very obvious common features in the electron diffraction patterns of the lambda and tau(mu) phases in the Al-Cr-Si system. The positions of the strong reflections and their intensity distributions are similar for the two structures. The relation of the reciprocal lattices of the lambda and tau(mu) phases is studied. By applying the strong-reflections approach, the structure factors of tau(mu) are deduced from the corresponding structure factors of the known lambda phase. Rules for selecting reflections for the strong-reflections approach are described. Similar to that of lambda, the structure of tau(mu) contains six layers stacked along the c axis in each unit cell. There are 752 atoms in each unit cell, 53 of them are unique. The corresponding composition of the tau(mu) model is Al(3.82 - x)CrSi(x). Simulated electron diffraction patterns from the structure model are in good agreement with the experimental ones. The arrangement of interpenetrated icosahedral clusters in the tau(mu) phase is discussed.

Journal Article↗

PubMed2006

Measurement of phosphorus content in normal and osteomalacic rabbit bone by solid-state 3D radial imaging.

In osteomalacia decreased mineralization reduces the stiffness and static strength of bone. We hypothesized that hypomineralization in osteomalacic bone could be quantified by solid-state (31)P magnetic resonance imaging (SS-MRI). Hypomineralization was measured with a 3D radial imaging technique at 162 MHz (9.4T) in rabbit cortical bone of hypophosphatemic (HY) and normophosphatemic (NO) animals. The results were compared with those obtained by quantitative micro-CT (micro-CT) and (31)P solution NMR. 3D images of 277 microm isotropic voxel size were obtained in 1.7 hr with SNR approximately 9. Mineral content was lower in the HY relative to the NO group (SS-MRI: 9.48 +/- 0.4 vs. 11.15 +/- 0.31 phosphorus wet wt %, P < 0.0001; micro-CT: 1114.6 +/- 28.3 vs. 1175.7 +/- 23.5 mg mineral/cm(3); P = 0.003). T(1) was shorter in the HY group (47.2 +/- 3.5 vs. 54.1 +/- 2.7 s, P = 0.004), which suggests that relaxation occurs via a dipole-dipole (DD) mechanism involving exchangeable water protons, which are more prevalent in bone from osteomalacic animals.

Anatomy, Cross-Sectional↗

PubMed2006

Protective effect of glutathione against lipopolysaccharide-induced inflammation and mortality in rats.

OBJECTIVE: To investigate protective effect of glutathione (GSH) against lipopolysaccharide (LPS)-induced inflammation and mortality in rats. METHODS: Male Sprague-Dawley rats were injected intraperitoneally (i. p.) with GSH (40 mg/kg) 30 min prior to LPS injection (20 mg/kg). Animal survival rate and the production of nitric oxide in serum were measured. Morphology of lung was observed using hematoxylin and eosin staining. Western blotting was used to assess the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and the phosphorylation of p38 in rat peritoneal macrophages. RESULTS: GSH significantly decreased LPS-induced mortality, inhibited serum NO production and eliminated lung histological injury. Furthermore, GSH inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins and the phosphorylation of p38 in LPS-stimulated rat peritoneal macrophages. CONCLUSIONS: These results indicated that GSH suppressed LPS-induced systemic inflammatory response in rats and p38 MAPK signal pathway was involved in this process.

Animals↗

PubMed2006

Hemithyroidectomy: the preferred initial surgical approach for management of Hurthle cell neoplasm.

BACKGROUND: The objective of this study was to evaluate the cancer risk of patient clinicopathologic characteristics to determine the optimal approach for the surgical management of individuals with Hurthle cell neoplasm (HN) diagnosed by cytology. METHODS: Patient clinicopathologic characteristics evaluated included age, sex, tumor size, and ipsilateral thyroid lobe nodularity. The association of these characteristics with a pathologic cancer diagnosis was evaluated using Fisher's exact test and Student t test. RESULTS: Of the 422 patients undergoing thyroidectomy, 27 presented with a fine-needle aspiration biopsy diagnosis of HN, and by pathologic assessment 7 HN patients (25.9%) had a cancer diagnosis. Although none of the clinicopathologic characteristics evaluated were able to reliably differentiate benign from malignant tumors, large tumor size and male sex were significantly associated with a pathologic diagnosis of Hurthle cell carcinoma (P < .05). CONCLUSIONS: Hemithyroidectomy represents the preferred initial surgical approach for the management of individuals presenting with nodular thyroid disease and a cytologic diagnosis of HN.

Adenoma, Oxyphilic↗

PubMed2006

Controlling chaotic robots with kinematical redundancy.

Robots with kinematical redundancy under the pseudoinverse control exhibit undesirable chaotic joint motion, which leads to erratic behaviors. In this study, we used the delayed feedback method to control chaotic motions of a planar 3R rigid and a planar 3R flexible redundant robot under the pseudoinverse control when the end-effector traces a closed-path repeatedly in the work space. It was demonstrated that chaotic motions of robots with kinematical redundancy can be turned into regular motion when the delayed feedback method was applied with some appropriate parameters. This study provides a new insight helpful to solve the repeatability problem of redundant manipulators.

Biomechanical Phenomena↗

PubMed2006

Metabolism and excretion of imrecoxib in rat.

The metabolism and excretion of imrecoxib, a novel and moderately selective cyclooxygenase-II inhibitor, were investigated in rat. The structures of metabolites were identified by mass spectrometry (MSn) and nuclear magnetic resonance. Metabolic profiles of imrecoxib in urine, bile and faeces were obtained by HPLC and LC/MSn, and cumulative excretion was determined by LC/MSn. Imrecoxib was extensively metabolized in rat after intravenous administration, with less than 2% of the dose excreted as parent drug in either urine or faeces. The major metabolic pathway was that the 4'-methyl group of imrecoxib was first oxidized to the 4'-hydroxymethyl metabolite (M4), followed by additional oxidation to 4'-carboxylic acid metabolite (M2). The dihydroxylated metabolite, 4'-hydroxymethyl-5-hydroxyl imrecoxib (M3), was further oxidized to 4'-hydroxymethyl-5-carbonyl metabolite (M5), and glucuronide conjugates of M2-4 were formed. After intravenous (5 mg kg-1) administration, the majority of the dose was recovered in the faeces. The dose was primarily excreted as the carboxylic acid metabolite in addition to the 4'-hydroxymethyl metabolite. The carboxylic acid metabolite was mainly excreted in faeces, while the 4'-hydroxymethyl metabolite was mainly excreted in urine.

Animals↗

PubMed2006

Studies on the alkaloid constituents of Evodia rutaecarpa (Juss) Benth var. bodinaieri (Dode) Huang and their acute toxicity in mice.

Six alkaloids (1-6) have been isolated from the fruits of Evodia rutaecarpa (Juss) Benth var. bodinaieri (Dode) Huang, two of which are new compounds, identified as 2-undecyl-4(1H)-quinolone (4) and 1-methyl-2-undecanone-10'-4(1H)-quinolone (5); the known compounds were identified as rutaecarpine (1), evodiamine (2), 1-methyl-2-undecyl-4(1H)-quinoline (3) and 2-undecanone-10'-4(1H)-quinolone (6). Compounds 1-5 were evaluated for their acute toxicity.

Alkaloids↗