Search PubMed⌕ Search

Biomedical subjects

M Zhang

Publications and source records attributed to M Zhang.

At least 127 records · Page 7Linked to original sources
PubMed2002

Macrophage-derived chemokine gene transfer results in tumor regression in murine lung carcinoma model through efficient induction of antitumor immunity.

Chemokine gene transfer represents a promising approach in the treatment of malignancies. Macrophage-derived chemokine (MDC) (CCL22) belongs to the CC chemokine family and is a strong chemoattractant for dendritic cells (DC), NK cells and T cells. Using adenoviral vectors, human MDC gene was transferred in vivo to investigate its efficacy to induce an antitumor response and to determine the immunologic mechanisms involved. We observed that intratumoral injection of recombinant adenovirus encoding human MDC (AdMDC) resulted in marked tumor regression in a murine model with pre-established subcutaneous 3LL lung carcinoma and induced significant CTL activity. The antitumor response was demonstrated to be CD4+ T cell- and CD8+ T cell-dependent. Administration of AdMDC induced chemoattraction of DC to the tumor site, facilitated DC migration to draining lymph nodes or spleen, and finally activated DC to produce high levels of IL-12. Furthermore, a significant increase of IL-4 production within the tumors was observed early after the AdMDC administration and was followed by the increase of IL-12 and IL-2 production. The levels of IL-2, IL-12 and IFN-gamma in serum, lymph nodes and spleen were also found to be higher in mice treated with AdMDC as compared with that in AdLacZ- or PBS-treated mice. The antitumor response induced by AdMDC was markedly impaired in IL-4 knockout mice, suggesting an important role of IL-4 in the induction of antitumor immunity by MDC. These results suggest that MDC gene transfer might elicit significant antitumor effects through efficient induction of antitumor immunity and might be of therapeutic potentials for cancer.

Adenoviridae↗
PubMed2002

Proliferative and nutritional dependent regulation of glyceraldehyde-3-phosphate dehydrogenase expression in the rat liver.

Glyceraldehyde-3-phosphate dehydrogenase is a multifunctional protein possessing numerous cytoplasmic and nuclear functions associated with cellular proliferation. Despite the emerging role of glyceraldehyde-3-phosphate dehydrogenase in regulating the proliferative process, there is a paucity of data regarding its expression and intracellular distribution in non-malignant proliferating hepatocytes. Thus the aim of the present study was to document the intracellular distribution of glyceraldehyde-3-phosphate dehydrogenase protein in proliferating hepatocytes derived from regenerating rat livers, and glyceraldehyde-3-phosphate dehydrogenase gene expression in fasted and re-fed rats following partial hepatectomy (PHx). Glyceraldehyde-3-phosphate dehydrogenase mRNA and protein expression were documented by Northern and Western blot analyses, respectively, at various times following 70% PHx in adult Sprague-Dawley rats. At 24 h post-surgery, glyceraldehyde-3-phosphate dehydrogenase mRNA expression was significantly increased in both PHx and sham operated rats (P < 0.001), respectively. Despite the increase in glyceraldehyde-3-phosphate dehydrogenase mRNA expression in both groups, only PHx rats had a significant increase in the nuclear fraction of glyceraldehyde-3-phosphate dehydrogenase protein (threefold increase compared to sham and baseline levels, P < 0.01), cytoplasmic levels of glyceraldehyde-3-phosphate dehydrogenase protein remained unaltered in both groups. In terms of the effects of feeding and fasting on rats there were no significant differences in glyceraldehyde-3-phosphate dehydrogenase mRNA levels, whether fasted or refed, in rats that had undergone PHx, 8 h earlier. On the other hand, glyceraldehyde-3-phosphate dehydrogenase mRNA levels were significantly increased in refed compared to fasted sham operated rats 8 h following surgery. Serum insulin concentrations were higher in the refed PHx and sham groups compared to their fasted counterparts. The results of this study indicate that although glyceraldehyde-3-phosphate dehydrogenase mRNA are altered to the same extent in PHx and sham-operated rats following surgery, increases in the nuclear fraction of glyceraldehyde-3-phosphate dehydrogenase protein only occur in PHx rats. The results also indicate that glyceraldehyde-3-phosphate dehydrogenase expression is affected by the nutritional status of animals undergoing abdominal sham surgery.

Animals↗
PubMed2002

Calcium-activated K+ channels of mouse beta-cells are controlled by both store and cytoplasmic Ca2+: experimental and theoretical studies.

A novel calcium-dependent potassium current (K(slow)) that slowly activates in response to a simulated islet burst was identified recently in mouse pancreatic beta-cells (Göpel, S.O., T. Kanno, S. Barg, L. Eliasson, J. Galvanovskis, E. Renström, and P. Rorsman. 1999. J. Gen. Physiol. 114:759-769). K(slow) activation may help terminate the cyclic bursts of Ca(2+)-dependent action potentials that drive Ca(2+) influx and insulin secretion in beta-cells. Here, we report that when [Ca(2+)](i) handling was disrupted by blocking Ca(2+) uptake into the ER with two separate agents reported to block the sarco/endoplasmic calcium ATPase (SERCA), thapsigargin (1-5 microM) or insulin (200 nM), K(slow) was transiently potentiated and then inhibited. K(slow) amplitude could also be inhibited by increasing extracellular glucose concentration from 5 to 10 mM. The biphasic modulation of K(slow) by SERCA blockers could not be explained by a minimal mathematical model in which [Ca(2+)](i) is divided between two compartments, the cytosol and the ER, and K(slow) activation mirrors changes in cytosolic calcium induced by the burst protocol. However, the experimental findings were reproduced by a model in which K(slow) activation is mediated by a localized pool of [Ca(2+)] in a subspace located between the ER and the plasma membrane. In this model, the subspace [Ca(2+)] follows changes in cytosolic [Ca(2+)] but with a gradient that reflects Ca(2+) efflux from the ER. Slow modulation of this gradient as the ER empties and fills may enhance the role of K(slow) and [Ca(2+)] handling in influencing beta-cell electrical activity and insulin secretion.

Action Potentials↗
PubMed2002

The expression of ADAM12 (meltrin alpha) in human giant cell tumours of bone.

AIMS: To examine the expression of ADAM12 (meltrin alpha), a member of the disintegrin and metalloprotease (ADAM) family, in human giant cell tumours of the bone, skeletal muscle tissue from human embryos, and human adult skeletal muscle tissue. METHODS: ADAM12 mRNA was detected by reverse transcription polymerase chain reaction and in situ hybridisation. RESULTS: ADAM12 mRNA was detected in 14 of the 20 giant cell tumours of bone and in three of the six tumour cell cultures. The expression of ADAM12 in cells cultured from the tumour was linked to the presence of multinucleated giant cells. ADAM12 mRNA could not be detected in the five adult skeletal muscle tissue samples, although it was found in the two embryonic skeletal muscle tissue samples. ADAM12 mRNA was localised to the cytoplasm of multinucleated giant cells and some mononuclear stromal cells. CONCLUSIONS: These results indicate that multinucleated giant cells are formed by the cell fusion of mononuclear stromal cells in giant cell tumours of bone and that ADAM12 is involved in the cell fusion process.

ADAM Proteins↗
PubMed2001

[Location of the pre-excitation part in Wolff-Parkinson-White syndrome by Doppler tissue imaging].

OBJECTIVE: To evaluate the feasibility of newly developed Doppler tissue imaging (DTI) for locating the early contraction sites in Wolff-Parkinson-White (WPW) syndrome. METHODS: The time-sequential changes in ventricular wall motion of thirty-three patients suffering from WPW syndrome were examined by DTI. The pre-excitation site was represented as a red region appearing on the myocardium right after the delta wave of the electrocardiogram and confirmed by electrophysiology. RESULT: Of 21 patients with left-sided accessory pathways, the early contractive sites were correctly identified by DTI in 18 patients, while the sites were determined by DTI in 8 of 12 patients with right-sided accessory pathways. There was no significant difference between the two groups (P > 0.05). CONCLUSION: The DTI system is helpful to localize the accessory pathways and evaluate the results after radiofrequency ablation.

Adolescent↗
PubMed2001

Molecular characteristics of non-small cell lung cancer.

We used hierarchical clustering to examine gene expression profiles generated by serial analysis of gene expression (SAGE) in a total of nine normal lung epithelial cells and non-small cell lung cancers. Separation of normal and tumor, as well as histopathological subtypes, was evident by using the 3,921 most abundant transcript tags. This distinction remained when only 115 highly differentially expressed tags were used. Furthermore, these 115 transcript tags clustered into groups suggestive of the unique biological and pathological features of the different tissues examined. Adenocarcinomas were characterized by high-level expression of small airway-associated or immunologically related proteins, whereas squamous cell carcinomas overexpressed genes involved in cellular detoxification or antioxidation. The messages of two p53-regulated genes, p21(WAF1/CIP1) and 14-3-3final sigma, were consistently underexpressed in the adenocarcinomas, suggesting that the p53 pathway itself might be compromised in this cancer type. Gene expression patterns observed by SAGE were consistent with results obtained by quantitative real-time PCR or cDNA array analyses by using a total of 43 lung tumor and normal samples. Thus, although derived from only a few tissue libraries, gene expression profiles obtained by using SAGE most likely represent an unbiased yet distinctive molecular signature for the most common forms of human lung cancer.

Base Sequence↗
PubMed2001

Expression of P2X2 and P2X3 receptor subunits in rat carotid body afferent neurones: role in chemosensory signalling.

1. Hypoxic chemotransmission in the rat carotid body (CB) is mediated in part by ATP acting on suramin-sensitive P2X purinoceptors. Here, we use RT-PCR, cloning and sequencing techniques to show P2X2 and P2X3 receptor expression in petrosal neurones, some of which develop functional chemosensory units with CB receptor clusters in co-culture. 2. Single-cell RT-PCR revealed that hypoxia-responsive neurones, identified electrophysiologically in co-culture, expressed both P2X2 and P2X3 mRNA. 3. Isohydric hypercapnia (10 % CO(2); pH 7.4) caused excitation of chemosensory units in co-culture. This excitation depended on chemical transmission, with ATP acting as a co-transmitter, since it was inhibited by reduction of the extracellular Ca(2+):Mg(2+) ratio and by the purinoceptor blocker suramin (50-100 microM). 4. Hypoxia and isohydric hypercapnia could separately excite the same chemosensory unit, and together the two stimuli interacted synergistically. 5. Using confocal immunofluorescence, co-localization of P2X2 and P2X3 protein was demonstrated in many petrosal somas and CB afferent terminals in situ. Taken together, these data indicate that ATP and P2X2-P2X3 purinoceptors play important roles in the peripheral control of respiration by carotid body chemoreceptors.

Adenosine Triphosphate↗
PubMed2001

Immunogenicity and protective efficacy of a vaccine prepared from 53 kDa truncated hepatitis E virus capsid protein expressed in insect cells.

Hepatitis E virus (HEV) is an enterically transmitted virus that causes acute hepatitis. Expression of recombinant HEV capsid protein in insect cells results in two major proteolytically-processed products of 56 and 53kDa which consist of amino acids (aa) 112-607 and 112-578, respectively. The only neutralization epitope identified to date is located at least partially between amino acids 578 and 607 meaning it should be present only in the 56 and not in the 53kDa protein. Previously, it was shown that vaccination with the 56kDa protein greatly reduced virus shedding and protected Rhesus monkeys from hepatitis E when challenged with a high intravenous dose of homologous or heterologous HEV. To evaluate the immunogenicity and protective efficacy of the 53kDa protein, we vaccinated Rhesus monkeys with this protein and challenged them with a high or low dose of homologous virus. Vaccination with the 53kDa protein greatly reduced virus shedding but did not protect against hepatitis following the high dose challenge. Virus was not detected in the vaccinated animals following the low dose challenge, suggesting that sterilizing immunity may have been achieved.

Alanine Transaminase↗
PubMed2001

Recombinant hepatitis E virus genomes infectious for primates: importance of capping and discovery of a cis-reactive element.

Hepatitis E virus recombinant genomes transcribed in vitro from two cDNA clones differing by two nucleotides were infectious for chimpanzees. However, one cDNA clone encoded a virus that was attenuated for chimpanzees and unable to infect rhesus monkeys. The second cDNA clone encoded a virus that infected both chimpanzees and rhesus monkeys and caused acute hepatitis in both. One mutation differentiating the two clones identified a cis-reactive element that appeared to overlap the 3' end of the capsid gene and part of the 3' noncoding region. Capping of the RNA transcripts was essential for infectivity.

Animals↗
PubMed2001

Sensitivity of mammalian cells expressing mutant ubiquitin to protein-damaging agents.

There is convincing evidence from studies in yeast that a functional ubiquitin/proteasome pathway is required to degrade misfolded or oxidatively damaged proteins but for technical reasons, it has been difficult to perform comparable studies in mammalian cells. To investigate the possibility that the ubiquitin/proteasome pathway is cytoprotective for mammalian cells, we have introduced epitope-tagged wild-type ubiquitin or dominant-negative mutant versions of ubiquitin into mouse HT4 neuroblastoma cells. Cells expressing mutant versions of ubiquitin were found to be sensitive to cadmium, an agent that causes oxidative damage to cellular components, and to canavanine, an amino acid analog that generates misfolded proteins. The greatest sensitivity to canavanine was observed in cells expressing a mutant version of ubiquitin unable to support the formation of Lys(48) linkages. Substrates of the proteasome were found to accumulate in these cells, suggesting a general deficit in proteolysis. Our data suggest that defects in the ubiquitin-mediated proteolytic system predispose mammalian cells to the toxic effects of abnormal protein.

Animals↗
PubMed2001

Butylamino-demethoxy-hypocrellins and photodynamic therapy decreases human cancer in vitro and in vivo.

2-Butylamino-2-demethoxy-hypocrellin A (BAHA) and B (BAHB) are new photosensitizers synthesized by a mild reaction of hypocrellins and butylamine. In BAHA and BAHB, the peri-hydroxylated perylenequinone structure of the parent hypocrellins is preserved and the red absorption is enhanced distinctly. Electron paramagnetic resonance spin trapping measurements and 9,10-diphenylanthracene bleaching studies were used to investigate the photodynamic action of BAHA and BAHB in the presence of oxygen. Singlet oxygen (1O2) and superoxide anion radical (O2(*-)) produced by illuminating BAHA and BAHB in aerobic solution have been observed. Compared with hypocrellin A and B, BAHA and BAHB primarily remained able to generate 1O2 and enhanced distinctly the O2(*-)-generating abilities. The photodynamic action of BAHA and BAHB in the therapy of cancer was investigated in vitro and in vivo. Both in vitro and in vivo results revealed a significant decrease in cancer cell growth. Laser or dye alone had no effect, indicating that intratumor BAHA and laser therapy may prove useful in unresectable cancer.

Animals↗
PubMed2001

Aclarubicin treatment restores SMN levels to cells derived from type I spinal muscular atrophy patients.

Proximal spinal muscular atrophy (SMA) is a common motor neuron disorder caused by mutation of the telomeric survival of motor neuron gene SMN1. The centromeric survival of motor neuron SMN2 gene is retained in all SMA patients but does not produce sufficient SMN protein to prevent the development of clinical symptoms. The SMN1 and SMN2 genes differ functionally by a single nucleotide change. This change affects the efficiency with which exon 7 is incorporated into the mRNA transcript. Thus, SMN2 produces less full-length mRNA and protein than SMN1. We have screened a library of compounds in order to identify ones that can alter the splicing pattern of the SMN2 gene. Here, we report that the compound aclarubicin increases the retention of exon 7 into the SMN2 transcript. We show that aclarubicin effectively induces incorporation of exon 7 into SMN2 transcripts from the endogenous gene in type I SMA fibroblasts as well as into transcripts from a SMN2 minigene in the motor neuron cell line NSC34. In type I fibroblasts, treatment resulted in an increase in SMN protein and gems to normal levels. Our results suggest that alteration of splicing pattern represents a new approach to modification of gene expression in disease treatment and demonstrate the feasibility of high throughput screens to detect compounds that affect the splicing pattern of a gene.

Aclarubicin↗
PubMed2001

Development of dengue virus replicons expressing HIV-1 gp120 and other heterologous genes: a potential future tool for dual vaccination against dengue virus and HIV.

BACKGROUND: Toward the goals of providing an additional vector to add to the armamentarium available to HIV vaccinologists and of creating a bivalent vaccine effective against dengue virus and HIV, we have attempted to create vectors which express dengue virus non-structural proteins and HIV immunogens. Previously we reported the successful construction of dengue virus replicons which lack structural genes necessary for virion release and spreading infection in culture but which can replicate intracellularly and abundantly produce dengue non-structural proteins. Here we attempted to express heterologous genetic material from these replicons. RESULTS: We cloned into a Deltapre-M/E dengue virus replicon genes for either green fluorescent protein (GFP), HIV gp160 or HIV gp120 and tested the ability of these constructs to express dengue virus proteins as well as the heterologous proteins in tissue culture after transfection of replicon RNA. CONCLUSIONS: Heterologous proteins were readily expressed from these constructs. GFP and gp120 demonstrated minimal or no toxicity. Gp160 expressing replicons were found to express proteins abundantly at 36 hours post transfection, but after 50 hrs of transfection, few replicon positive cells could be found despite the presence of cellular debris positive for replicon proteins. This suggested that gp160 expressed from dengue virus replicons is considerably more toxic than either GFP or gp120. The successful expression of heterologous proteins, including HIV gp120 for long periods in culture suggests this vector system may be useful as a vaccine vector, given appropriate delivery methods.

Dengue↗
PubMed2001

Molecular characterization of a mouse short chain dehydrogenase/reductase active with all-trans-retinol in intact cells, mRDH1.

Metabolic activation of retinol (vitamin A) via sequential actions of retinol and retinal dehydrogenases produces the active metabolite all-trans-retinoic acid. This work reports cDNA cloning, enzymatic characterization, function in a reconstituted path of all-trans-retinoic acid biosynthesis in cell culture, and mRNA expression patterns in adult tissues and embryos of a mouse retinol dehydrogenase, RDH1. RDH1 represents a new member of the short chain dehydrogenase/reductase superfamily that differs from other mouse RDH in relative activity with all-trans and cis-retinols. RDH1 has a multifunctional catalytic nature, as do other short chain dehydrogenase/reductases. In addition to retinol dehydrogenase activity, RDH1 has strong 3alpha-hydroxy and weak 17beta-hydroxy steroid dehydrogenase activities. RDH1 has widespread and intense mRNA expression in tissues of embryonic and adult mice. The mouse embryo expresses RDH1 as early as 7.0 days post-coitus, and expression is especially intense within the neural tube, gut, and neural crest at embryo day 10.5. Cells cotransfected with RDH1 and any one of three retinal dehydrogenase isozymes synthesize all-trans-retinoic acid from retinol, demonstrating that RDH1contributes to a path of all-trans-retinoic acid biosynthesis in intact cells. These characteristics are consistent with RDH1 functioning in a path of all-trans-retinoic acid biosynthesis starting early during embryogenesis.

Alcohol Oxidoreductases↗
PubMed2001

Release of glycosaminoglycans in physiological saline and water by wet-spun chitin--acid glycosaminoglycan fibers.

The present study sought to prepare novel chitin- acid glycosaminoglycan fibers that released a portion of the glycosaminoglycans in animal body fluids for use as novel biocompatible dressing materials (artificial skin) in the veterinary and clinical fields. A clear solution of sodium N-acetylchitosan salt (alkaline chitin) mixed with sodium hyaluronate, sodium heparin, sodium chondroitin 4-sulfate, sodium chondroitin 6-sulfate, or sodium dermatan sulfate in 14% aqueous NaOH was spun through a viscose-type spinneret into a 10% aqueous H(2)SO(4) solution saturated with (NH(4))(2)SO(4) at room temperature. The result was chitin fibers containing 5--33% glycosaminoglycans. In a dry state these fibers were white and had a soft feel but they were mechanically weak (0.31--0.69 g/denier tenacity and 3.1--10.6% elongation). Portions (85--97%) of the glycosaminoglycans were released from the fibers by soaking them in physiological saline or distilled water. Scanning electron microscopy analyses revealed a smooth striped surface on the original filaments, and a scaly surface appeared on the chitin filament after soaking.

Animals↗
PubMed2001

Blocking tumor growth, invasion, and metastasis by maspin in a syngeneic breast cancer model.

Maspin is a unique serine protease inhibitor of which the down-regulation is associated with the development of breast cancers. In vitro, recombinant maspin inhibits tumor cell migration and invasion. Overexpression of maspin in transgenic mice is protective against tumor progression. Additionally, maspin acts as an angiogenesis inhibitor in rat cornea model and in a xenograft tumor model. To additionally prove that maspin is directly involved in the suppression of tumor growth and metastasis, we tested maspin in a new syngeneic mammary tumor model, TM40D. This model involves the implantation of TM40D mammary tumor cells orthotopically to the mammary gland; tumors grew within the gland and then become invasive and metastatic to other organs. Here we demonstrate that TM40D cells in implanted mammary glands are highly invasive. Overall, a 75% rate of invasion and metastasis was observed in this model. However, both primary tumor growth and metastasis were significantly blocked in TM40D cells that overexpress maspin as a consequence of plasmid or retrovirus infection. Maspin-transfected tumors tended to have tumor encapsulation and less necrosis, which were associated with better prognosis and lower invasiveness. Thus, maspin can block primary tumor growth as well as invasion and metastasis. These data support the concept that maspin has a strong protective role against tumor progression.

Animals↗
PubMed2001

DIgR1, a novel membrane receptor of the immunoglobulin gene superfamily, is preferentially expressed by antigen-presenting cells.

A novel membrane receptor of immunoglobulin gene superfamily (IgSF) has been identified from mouse dendritic cells (DC) and designated as DC-derived Ig-like receptor 1 (DIgR1). It encodes a 228-amino-acid (aa) residue polypeptide with a 21-aa signal peptide, a 20-aa transmembrane region, a 189-aa extracellular region, and a 19 aa intracellular region. Its extracellular region contains a single V domain of Ig. So it is a novel type I transmembrane glycoprotein of IgSF. DIgR1 shows significant homologies to human CMRF-35 antigens and polymeric immunoglobulin receptors (pIgR). The mRNA expression of DIgR1 was highly abundant in mouse spleen. The preferential expression of DIgR1 mRNA is observed in the known antigen-presenting cells (APC) including DC, monocytes/macrophages, and B lymphocytes. A 40 kDa of protein in NIH/3T3 cells transfected with the DIgR1 cDNA was detected by Western blot analysis using anti-DIgR1 polyclonal antibodies. The expression of DIgR1 protein on DC is not regulated by LPS stimulation. Further study should be conducted to investigate what were biological functions of DIgR1 in the immunobiology of APC.

Amino Acid Sequence↗