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Biomedical subjects

G Zhu

Publications and source records attributed to G Zhu.

At least 289 records · Page 16Linked to original sources
PubMed1989

SV40-transfected human melanocyte sensitivity to growth inhibition by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate.

Normal human melanocytes, which require the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) for growth in culture, were transfected with a SV40 T-antigen-containing plasmid by using the technique of electroporation, and were scored for colonies of morphologically altered cells. The frequency of transformed colonies was higher when selection was done in the absence rather than the presence of TPA in the medium. Three cell lines derived from transformed colonies were characterized. All show an enhanced growth rate compared to parental cells, anchorage independence, loss of dependence on medium supplements for growth, chromosomal abnormalities, an extended life span, and growth inhibition by TPA. They express nerve growth factor receptor and Mr 97,000 protein, melanotransferrin, two antigens usually associated with melanocytic cells, but the transformed cells are not pigmented. The three cell lines underwent crisis at about passage 10 posttransfection; one cell line recovered and appears to have unlimited growth potential. None of the cell lines is tumorigenic. They should be interesting models for studying multistage carcinogenesis in human cells and transcriptional activation by TPA.

Antigens, Polyomavirus Transforming↗
PubMed1988

Distribution of energy in polymers due to incident electrons and protons.

The recoil spectrum of nuclei in polymers for incident protons below 10 MeV in energy is calculated by using the Rutherford cross-section with screening corrections. Employing the work of McKinley and Feshbach on the Coulomb scattering of relativistic electrons by nuclei, the recoil spectrum of the nuclei is also calculated for electron energies varying from threshold to 10 MeV. The partitioning of energy between electronic excitation and ionization and nuclear recoil is then studied to search for possible difference in polymer radiation response as a function of radiation energy and type.

Electrons↗
PubMedDate not supplied

Efficient adenoviral gene transfer to kidney cortical vasculature utilizing a fiber modified vector.

BACKGROUND: The alpha v integrin is present in vascular endothelium, including that of the kidney. It is also upregulated in the presence of inflammatory cytokines and in some neoplasms. In an effort to transduce vascular endothelial cells, we compare in vitro and in vivo adenoviral gene transfer of a vector with a high affinity peptide ligand to the alpha v integrin incorporated into the fiber coat protein AdZ.F(RGD) to an unmodified vector, AdZ. METHODS: Cell transduction assays were performed on human umbilical vein endothelial cells (HuVEC) and human pulmonary epithelial cells (A549). In vitro competition assays were performed in the presence of either wild type (F5K) or chimeric (F5K(RGD)) soluble recombinant fiber protein. Transduction efficiency was determined by quantitative beta-galactosidase activity. In vivo gene transfer was compared infusing either AdZ or AdZ.F(RGD) into the left renal artery of the rat and assaying beta-galactosidase staining of the kidney. Gene transfer was also evaluated in the presence of a competitive RGD or control RGE peptide. RESULTS: There was a marked increase in transgene expression in HuVEC cells with AdZ.F(RGD) as compared to AdZ. The increased expression with AdZ.F(RGD) was more prominent in the endothelial as opposed to the epithelial cell line. Furthermore pre-incubation of these cells with either F5K or F5K(RGD) soluble fiber protein markedly decreased beta-galactosidase activity of AdZ, whereas only the F5K(RGD) decreased beta-galactosidase activity of AdZ.F(RGD). AdZ.F(RGD) also resulted in significantly enhanced beta-galactosidase expression in the vascular endothelium of the kidney (for comparable amounts of virus injected) as well as significantly higher gene transfer to cortical vasculature. Coinfusion of an RGD peptide with AdZ.F(RGD) blocked gene transfer whereas a control RGD peptide did not. CONCLUSION: We conclude that incorporating a high affinity peptide ligand into the adenoviral fiber protein can preferentially enhance in vitro and in vivo adenoviral transfection efficiency in endothelial cells. Enhancing transfection efficiency will not only broaden the scope of disease processes addressed with adenoviral vectors but also allow the use of lower titer, thereby limiting toxicity. This vector has additional potential to transduce endothelial cells within tumors or ischemic tissue where alpha v integrins are upregulated.

Adenoviridae↗
PubMedDate not supplied

Synthesis and characterization of two novel [Ru(bpy)(2)(phen)](2+)-based electrochemiluminescent labels.

Two novel electrochemiluminescent labels, bis(2, 2'-bipyridine)[5-(3-carboxylic acid-propionamido)-1, 10-phenanthroline]ruthenium(II) hexafluorophosphate dihydrate and bis(2,2'-bipyridine)[5-(4-carboxylic acid-butanamido)-1, 10-phenanthroline]ruthenium(II) hexafluorophosphate dihydrate, were synthesized and confirmed by IRelemental analysis, and (1)H-NMR spectra were completely assigned using the (1)H-(1)H COSY technique. Cyclic voltammograms with different scan rates showed quasi-reversible electrochemical behaviour of the two Ru (II) complex labels in MeCN solution. Electronic absorption, photoluminescence and electrochemiluminescence of Ru(II) complexes were also characterized.

Electrochemistry↗
PubMedDate not supplied

Using neural network predicted secondary structure information in automatic protein NMR assignment.

In CAPRI, an automated NMR assignment software package that was developed in our laboratory, both chemical shift values and coupling topologies of spin patterns are used in a procedure for amino acids recognition. By using a knowledge base of chemical shift distributions of the 20 amino acid types, fuzzy mathematics, and pattern recognition theory, the spin coupling topological graphs are mapped onto specific amino acid residues. In this work, we investigated the feasibility of using secondary structure information of proteins as predicted by neural networks in the automated NMR assignment. As the 1H and 13C chemical shifts of proteins are known to correlate to their secondary structures, secondary structure information is useful in improving the amino acid recognition. In this study, the secondary structures of proteins predicted by the PHD protein server and our own trained neural networks are used in the amino acid type recognition. The results show that the predicted secondary structure information can help to improve the accuracy of the amino acid recognition.

Algorithms↗
PubMedDate not supplied

Substance P primes murine peritoneal macrophages for an augmented proinflammatory cytokine response to lipopolysaccharide.

We have recently shown that substance P (SP) participates in the stress-induced modulation of elicited, peritoneal macrophage function. This study reports the in vitro effects of SP on macrophage activity. We show by an MTT bioassay that SP significantly increases cellular metabolic activity. We show by ELISA that preincubating (priming) the macrophages with SP, prior to the incubation with lipopolysaccharide (LPS), results in a significant enhancement of proinflammatory cytokine secretion, relative to LPS alone. Finally, we show that somatostatin can antagonize the SP-induced enhancement of cytokine secretion. The above results demonstrate the importance of the temporal sequence in which stimuli are administered, in vitro, and indicate that SP can act as first signal in the cascade of macrophage activation. We postulate that stress, via the secretion of SP and other sensory neuropeptides, may play a role in the pathogenesis of certain inflammatory diseases of unknown etiology.

Animals↗