Biomedical subjects

Ming Zhang

Publications and source records attributed to Ming Zhang.

At least 199 records · Page 11Linked to original sources

PubMed2003

Census of genes expressed in porcine embryos and reproductive tissues by mining an expressed sequence tag database based on human genes.

A total of 98,898 expressed sequence tags (ESTs) derived from embryos and reproductive tissues in pigs were identified in the GenBank "est_others" database. Pig embryos were collected at 11, 12, 13, 14, 15, 20, 30, and 45 days after gestation. The reproductive tissues were sampled from testis, ovary, endometrium, hypothalamus, anterior pituitary, uterus, and placenta. A gene-oriented approach was developed to annotate these porcine EST sequences to census the genes expressed from these sources. Of the 33 308 mRNA sequences from the human genes used as references (data accessed on 1 November 2002), 9410 had the porcine EST homologs expressed in embryos and 11 795 had the EST homologs expressed in reproductive tissues. The entire genome contributes at least 28.3% of its genes to embryo development and 35.4% of its genes to reproduction. Using the EST entry numbers as indicators of gene expression, we determined that the gene expression patterns differ significantly between embryos and reproductive tissues in pigs. The basic active genes were identified for each source, but most of them are not coexpressed abundantly. Few genes were expressed on the Y chromosome (P < 0.01), but they may represent counterparts of the double-dose genes that remain active in an inactivated X chromosome in females but are needed for proper development and growth. The census provides a panel of transcripts in a broad sense that can be used as targets to study the mechanisms involved in embryo development and reproduction in pigs and other mammals, including humans.

Animals↗

PubMed2003

Single-stranded DNA aptamers that bind differentiated but not parental cells: subtractive systematic evolution of ligands by exponential enrichment.

In this paper, single-stranded (ss)DNA aptamers with capability to distinguish differentiated PC12 cells from normal PC12 cells were selected by subtractive systematic evolution of ligands by exponential enrichment (SELEX) method. Before each round of selection, randomized ssDNAs were incubated with regular PC12 cells to eliminate those that recognize the common cellular components of both differentiated and undifferentiated PC12 cells. After six rounds of cell-based selection, both of individual aptamers and aptamers of the sixth round pool were found binding to differentiated PC12 cells, but not to the parental PC12 cells. The aptamers of the starting pool showed no such binding. Sequence analysis illustrated that the amount of G content in central random region of these aptamers was much higher than that of the starting pool, which would be expected to be average. The aptamers obtained from this method were also able to identify differentiated PC12 cells from a mixture of both normal and differentiated cells. The results indicate that subtractive SELEX is a useful tool in finding ligands to specific biological markers that distinguish a subtype of cells from cells of homologous origin, such as carcinoma cells among normal epithelial tissues. Both these aptamers and their markers may play important roles in basic research and clinical diagnosis.

Animals↗

PubMed2003

Potent activity of soluble B7RP-1-Fc in therapy of murine tumors in syngeneic hosts.

We have characterized a receptor:ligand pair, ICOS:B7RP-1, that is structurally and functionally related to CD28:B7.1/2. We reported previously that B7RP-1 costimulates T cell proliferation and immune responses (Yoshinaga et al., Nature 1999;402:827-32; Guo et al., J Immunol 2001;166:5578-84; Yoshinaga et al., Int Immunol 2000;12:1439-47). We report that B7RP-1-Fc causes rejection or growth inhibition of Meth A, SA-1 and EMT6 tumors in syngeneic mice. Established Meth A tumors were rejected effectively with a single dose of B7RP-1-Fc, however, the treatment was less effective on larger tumors. Mice that rejected Meth A tumors previously by Day 30, also rejected a subsequent Meth A challenge on Day 60, without additional B7RP-1-Fc treatment, indicating a long-lived memory response. Tumor cells believed to be less immunogenic, such as P815 and EL-4 cells, were less responsive to this treatment. The EL-4 responsiveness to the B7RP-1-Fc treatment was enhanced, however, by pre-treatment of the mice with cyclophosphamide. As expected, T cells appeared to be targeted by B7RP-1-Fc treatment. Thus, the administration of soluble B7RP-1-Fc may have therapeutic value in generating or enhancing anti-tumor activity in a clinical setting.

Animals↗

PubMed2003

Regional delivery and selective expression of a high-activity yeast cytosine deaminase in an intrahepatic colon cancer model.

A major potential limitation to the success of enzyme prodrug gene therapy is the toxicity that could result from gene expression in normal tissues. In this study, we investigated the use of an enhanced human carcinoembryonic antigen (CEA) promoter for yeast cytosine deaminase (yCD), which converts 5-fluorocytosine to 5-fluorouracil, to increase targeting while maintaining activity both in cell culture and in nude rats bearing intrahepatic xenografts. We found that an enhanced CEA-yCD adenoviral vector can achieve significantly greater yCD expression in CEA-expressing colon carcinoma cell lines (LoVo, HT29, and CaCo2) compared with a nonspecific Rous sarcoma virus-yCD virus. In contrast, infection with CEA-yCD led to lower or equivalent yCD expression in normal hepatocytes or fibroblasts compared with that produced by the RSV-yCD. Adenovirus administered in the portal vein or the hepatic artery of nude rats bearing intrahepatic LoVo colon carcinomas could mediate beta-galactosidase expression equally in liver and tumors under the control of cytomegalovirus, a nonspecific promoter. However, infusion of CEA-yCD virus markedly increased yCD expression in tumors over normal liver (>4-fold) measured both by levels of mRNA and yCD activity. Moreover, the efficiency of 5-fluorocytosine conversion into 5-fluorouracil in tumors was significantly higher than that in normal liver ( approximately 3-fold) in rats receiving portal venous viral infusion of CEA-yCD and subsequent 5FC treatment. Thus, an enhanced CEA promoter can preferentially stimulate yCD gene expression in CEA-expressing cells in vivo. Such tumor-specific expression should prove useful in colorectal cancer gene therapy to achieve selective prodrug conversion in tumors.

Adenoviridae↗

PubMed2003

What arteries are detectable in the precarinal space on contrast-enhanced CT?

Although the precarinal space is critical in the interpretation of computed tomography (CT) of the thorax, vascular structures within the space have not been well documented. The aim of this study was to investigate vascular structures in the precarinal space that are detectable with contrast-enhanced CT scans. Contrast-enhanced CT chest scans from 90 patients aged 17-78 years (41 male, 49 female) were analyzed retrospectively. Twenty-two cadavers aged 54-93 years (13 male, 9 female) were used for gross anatomic study. We found that 9 of 90 cases of the contrast-enhanced CT scans had vessel-like structures detectable in the precarinal space, located primarily anterior to the right main bronchus. Single or double arteries were identified in the precarinal space of 19 cadavers. Thirteen of the 23 arteries observed were the right bronchial artery and 10 were the left bronchial artery. In two cadavers, a single right bronchial artery (2.5 and 4.0 mm in diameter), which could have been detected with contrast-enhanced CT, originated from the aortic arch and the root of the left subclavian artery and coursed in the precarinal space. Based on the variation in the location and size of the bronchial arteries observed in this study, we suggest that vascular structures are detectable in the precarinal space with contrast-enhanced CT, particularly anterior to the right main bronchus.

Adolescent↗

PubMed2003

Visualization and quantification of renal R2* changes during water diuresis.

PURPOSE: To refine and evaluate methods for analysis of renal blood oxygenation level dependent (BOLD) MRI data. MATERIALS AND METHODS: Color R2* maps and regions-of-interest (ROIs) on the borderline between cortex and medulla were applied to renal BOLD MRI data of a group of 13 young female subjects. RESULTS: The distribution of R2* within the kidneys was heterogeneous and the response of human kidneys to water diuresis was patchy. R2* values at the cortico-medullary border region have a smaller variation than in wider cortical or medullary regions and are sensitive to physiological changes produced by water diuresis. CONCLUSION: These methods provide improved visualization of the regional distribution of R2* and its variations and more precise quantification of the changes in renal R2* produced by water diuresis.

Adult↗

PubMed2003

Maspin expression in invasive breast cancer: association with other prognostic factors.

Maspin is a unique serine protease inhibitor with a molecular weight of 42 kDa. It has been shown to inhibit tumour cell motility and invasion in cell culture, and tumour growth and metastasis in animal models. There is very limited data on the prognostic utility of maspin in human breast cancer. We performed a preliminary study to assess the associations of maspin with other established prognostic factors in invasive breast cancer (IBC). 1068 paraffin-embedded IBCs were immunohistochemically stained with a monoclonal antibody to maspin. A nuclear signal was present in 96% and a cytoplasmic signal in 35% of the cases. Nuclear staining was related to oestrogen (ER) and progesterone receptor (PR) positivity (p < 0.0001), but not to S-phase fraction (SPF) or ploidy. Cytoplasmic staining was related to ER and PR negativity (p < 0.0001), high SPF (p < 0.0001), and aneuploidy (p = 0.003). Thus, maspin nuclear staining was significantly associated with good prognostic factors, while cytoplasmic staining was associated with poor prognostic markers. These findings suggest that the presence of maspin in two different compartments of the cell may have different biological and clinical implications. Additional studies are needed to evaluate further this expression profile of maspin in breast cancer.

Antibodies, Monoclonal↗

PubMed2003

Expression of HSP70 in peripheral lymphocytes of the patients with allergic rhinitis.

The expression levels of heat shock protein 70 (HSP70) from peripheral lymphocytes of the patients with allergic rhinitis (AR) and the clinical implication were investigated. In the morning, 3 ml of fasting venous blood was taken out. The lymphocytes were isolated by using Ficoll-Hypaque and the expression of HSP70 in the lymphocytes was detected by using Western blot. In the AR patients the HSP70 level (41.49 +/- 15.77 integrated optical density, IOD) were significantly higher than that in the control group (23.89 +/- 10.13 IOD, P < 0.05). Western blot demonstrated that HSP70 bands in AR patients were more intensive than those in the control group. It was concluded that the elevated HSP70 level in peripheral lymphocytes of the AR patients might contribute to the development of AR.

Adult↗

PubMed2003

Experimental study of relationship between intracoronary alcohol injection and the size of resultant myocardial infarct.

BACKGROUND: Hypertrophic obstructive cardiomyopathy (HOCM) is a complex disease with unique pathophysiologic characteristics and a great diversity of morphologic,functional and clinical features. Percutaneous transluminal septal myocardial ablation (PTSMA) using alcohol injection via a catheter into the septal branch of the left anterior descending coronary artery has been recently introduced as a promising nonsurgical therapy for HOCM. However, the relationship between the volume and velocity of intracoronary injection of absolute alcohol and the size of the resultant myocardial infarct has not been investigated. We therefore studied such a relationship in piglets. OBJECTIVES: To investigate the relationship between the volume and velocity of selective intracoronary alcohol injection by means of a catheter and the size of the resultant myocardial infarction. METHODS: Twenty piglets were equally divided at random into four groups (n=5 in each) according to the volume and the velocity of intracoronary absolute alcohol injection and the coronary arteries injected. Group I: the volume and velocity of injection of alcohol into the left circumflex coronary artery (LCX) were 0.5 ml and 0.2 ml/s, respectively. Group II: the volume and velocity of injection into LCX were 2.0 ml and 0.2 ml/s, respectively. Group III: the volume and velocity of injection of alcohol into the left anterior descending coronary artery (LAD) were 1.2 ml and 0.06 ml/s, respectively. Group IV: the volume and velocity of injection into the LAD were 1.2 ml and 1.2 ml/s, respectively. The resultant myocardial infarcts were then quantitatively measured 6 h after myocardial ablation. RESULTS: The myocardial infarct size for group I was 4.26+/-2.71(%), for group II was 10.12+/-4.55(%), for group III was 5.84+/-1.21(%) and for group IV was 7.11+/-1.63(%). There were significant differences in myocardial infarct size with different volumes of intracoronary absolute alcohol injection (0.02<P<0.05). but there were no apparent differences found in myocardial infarct size with different velocities of intracoronary alcohol injection (0.05<P<0.2). CONCLUSIONS: The myocardial infarct size is directly related to the volume of intracoronary absolute alcohol injection during myocardial ablation by a catheter, but has no relation to the injection velocity.

Animals↗

PubMed2003

Biomechanical responses of the intervertebral joints to static and vibrational loading: a finite element study.

OBJECTIVE: This study was performed to investigate the time-dependent responses of the intervertebral joint to static and vibrational loads. DESIGN: A poroelastic finite element model was established to analyse the fluid flow, stress distribution and deformation of the intervertebral disc. BACKGROUND: Long-term exposure to whole body vibration is highly associated with disc degeneration and low back pain. It is hypothesized that moderate vibrational loading may increase the efficiency of fluid and nutritional transport of the intervertebral disc while prolonged static and excessive vibrational loading may have deleterious effect. METHODS: A three-dimensional finite element model was established using the actual geometry of the L4-L5 lumber motion segment. Nonlinear poroelastic properties were assigned to the intervertebral disc and cancellous bone. Static and vibrational loads were applied and the responses of fluid flow and stress distributions were analysed. RESULTS: The finite element model showed that the loads carried by the annulus and the facets increased with time under static loading. The fluid flow and deformation of the intervertebral disc were dependent on the loading frequency. CONCLUSION: Vibration loading may be able to enhance disc fluid exchange via the fluid pumping mechanism. RELEVANCE: The predicted responses implied that vibrational motion may be important in facilitating fluid and metabolic transport of the intervertebral disc.

Biomechanical Phenomena↗

PubMed2003

Effect of alteration of the C-terminal extension on the maturation and folding of the large subunit of the Escherichia coli hydrogenase-2.

Large subunits of NiFe-hydrogenases undergo a unique maturation process in which the last step consists of the endoproteolytic cleavage of the C-terminal extension after the Ni-Fe metal center has been assembled. To assess in vivo the influence of alteration of the C-terminal extension on the processing, green fluorescence protein (GFP) was fused to the C-terminus of the large subunit (HybC) of the Escherichia coli hydrogenase 2. Interestingly, no processing of HybC-GFP was observed. In addition, the chromophore of GFP was not formed, implying a nonproductive folding of the upstream HybC moiety. These results strongly suggest that the alteration of the C-terminus of the hydrogenase 2 large subunit interferes with the folding and processing of HybC.

Amino Acid Sequence↗

PubMed2003

Correlated expression of inducible nitric oxide synthase and P53, Bax in benign and malignant diseased gallbladder.

Our goal has been to investigate the expression and correlated significance of inducible nitric oxide synthase (iNOS) and P53, Bax in benign and malignant gallbladder diseases. We detected the expression of iNOS, P53 and Bax in the gallbladder wall by SP immunohistochemistry in 16 cases of chronic cholecystitis, 11 cases of chronic cholecystitis with adenomyoma and 24 cases of gallbladder adenocarcinoma. The percentage of positively marked tumor cells was counted under microscope and the intensity of immunoreactivity was graded. SPSS10.0 statistical software was applied for statistical analysis. In this study, we found that: (1) Both benign and malignant diseased gallbladder wall expressed iNOS and Bax. Compared to benign diseased gallbladders, their expression in adenocarcinoma was decreased (p < 0.05), P53 was expressed strongly only in nuclei of adenocarcinoma cells of some cases. (2) In benign and malignant diseased gallbladders, iNOS expression was related positively to Bax (p < 0.01), the expression of P53 and Bax had a negative relationship (p < 0.01). The results suggested that both chronic cholecystitis and chronic cholecystitis with adenomyoma carry the risk of becoming malignant, especially the latter. NO is an important mediated molecule in cancer, there are intimate relationships between gallbladder cancer and apoptosis.

Acute Disease↗

PubMed2003

Ionizing radiation increases adenovirus uptake and improves transgene expression in intrahepatic colon cancer xenografts.

Specific targeting and transgene expression in tumors are critical in adenovirus gene therapy for intrahepatic colon carcinoma metastases. In this study, we investigated if ionizing radiation could increase adenoviral uptake by cells. Various human cell lines and rat hepatocytes were irradiated prior to exposure to a cytomegalovirus (CMV) promoter-driven green fluorescent protein (GFP) marker gene adenoviral vector. We found that gamma-radiation increased the number of GFP-positive cells in a dose- and time-dependent manner for most cells, ranging from 4.6- to 27.1-fold after a 4-Gy treatment. No induction occurred for lentiviral vector, lipofection, or naked plasmid exposure. Preincubation of cells with adenovirus failed to show an increase, suggesting that radiation might mediate adenoviral infection by inducing viral uptake into cells. We demonstrated that radiation induced internalization of a fluorescence-labeled adenovirus (Cy3-Ad) and an increase in intracellular viral DNA content. Rats bearing intrahepatic colon carcinoma xenografts were irradiated in the tumor region followed by portal venous administration of an adenoviral vector containing a CMV-beta-galactosidase (beta-gal) gene. Radiation increased beta-gal activity in tumors as much as 5.4-fold after a 25-Gy treatment. These data suggest that a combination of regional radiation treatment with adenovirus gene therapy is a rational strategy for improving adenoviral targeting and transgene expression in tumors.

Adenoviridae↗

PubMed2003

Maspin functions as tumor suppressor by increasing cell adhesion to extracellular matrix in prostate tumor cells.

PURPOSE: Maspin, a unique member of the serine protease inhibitor family, shows tumor suppressing activity for breast cancer progression and metastasis. Few studies have directly linked maspin function to prostate cancer. We used prostate tumor cells derived from the TRAMP (transgenic adenocarcinoma of mouse prostate) prostate tumor model to study the tumor suppressive function of maspin in prostate cancer. MATERIALS AND METHODS: Maspin cDNA was introduced via a retroviral plasmid into TRAMP C2N prostate tumor cells, which are aggressive and invasive in nature. We investigated the tumorigenesis of these stable cell lines in vitro by assessing the growth rate, anchorage independence and adhesion to extracellular matrix proteins such as fibronectin and laminin. RESULTS: Stable cell lines expressing maspin had decreased tumorigenic potential, as assessed by anchorage independent growth in soft agar assay compared with controls. Maspin stable transfectants showed decreased metastatic potential, as evaluated by modified Boyden chamber assay and increased adhesion to fibronectin and laminin. CONCLUSIONS: Our study confirms that maspin has a tumor suppressive role not only in breast cancer, but also in prostate cancer. The data in this study suggest that maspin can decrease the tumorigenic and metastatic potential of prostate tumors, most probably by remodeling cell-extracellular matrix interactions or triggering extracellular matrix mediated signaling pathways that negatively regulate tumor migration and invasion.

Adenocarcinoma↗

PubMed2003

Covalent immobilization of O-butyrylchitosan with a photosensitive hetero-bifunctional crosslinking reagent on biopolymer substrate surface and bloodcompatibility characterization.

O-Butyrylchitosan (OCS) was covalently immobilized onto a substrate (suture and PTFE) surface using the photosensitive hetero-bifunctional crosslinking reagent 4-azidobenzoic acid, which was previously bonded to OCS by the reaction between an acid group of the crosslinking reagent and a free amino group of OCS. The immobilization was accomplished by irradiating the modified OCS coated on the substrate surface with ultraviolet light to photolyze azide groups, thus the crosslinking OCS was immobilized on the substrate surface. The result indicated that OCS molecules immobilized on the substrate, and significantly reduced the fibrinogen adsorption and the deposition and spreading of platelets, demonstrating superior bloodcompatibility. Therefore, OCS could be developed into bloodcompatible biomaterial that used to modify the biomedical devices, such as PTFE and Dacron vascular prostheses surface.

Animals↗

PubMed2003

Role of maspin in tumor metastasis and angiogenesis.

Cancer is one of the leading causes of mortality in developed countries such as the USA. In 1998, there were more than 280,000 and 250,000 cancer related deaths in males and females, respectively. In males, lung and prostate cancers accounted for almost half of these deaths, whereas in females, lung and breast cancers were the leading causes of cancer mortalities. Therefore, the study of cancer has been of the utmost importance to patients, doctors, and researchers alike. A variety of cellular processes occur in the precancerous cells that contribute to the development and progression to cancer. Not surprisingly, all of these cellular processes have been targeted for anticancer therapy. A novel serpin, maspin, has demonstrated a robust effect on a variety of these cancer progression steps. A number of studies have shown that maspin inhibits angiogenesis and tumor cell growth and invasion both in vitro and in vivo. In addition, maspin promotes cell adhesion to the basement membrane and extracellular matrix components. Efforts underway to understand the molecular mechanisms involved in the diverse functions influenced by maspin have yielded promising results and shed light on the cancer pathways.

Animals↗

PubMed2003

DNA polymerase zeta: new insight into eukaryotic mutagenesis and mammalian embryonic development.

Information about the mechanisms that generate mutations in eukaryotes is likely to be useful for understanding human health concerns, such as genotoxicity and cancer. Eukaryotic mutagenesis is largely the outcome of attacks by endogenous and environmental agents. Except for DNA repair, cell cycle checkpoints and DNA damage avoidance, cells have also evolved DNA damage tolerance mechanism, by which lesion-targeted mutation might occur in the genome during replication by specific DNA polymerases to bypass the lesions (translesion DNA synthesis, TLS), or mutation on undamaged DNA templates (untargeted mutation) might be induced. DNA polymerase zeta (pol zeta), which was found firstly in budding yeast Saccharomyces cerevisiae and consists of catalytic subunit scRev3 and stimulating subunit scRev7, has received more attention in recent years. Pol zeta is a member of DNA polymerase eta subfamily, which belongs to DNA polymerase B family, and exists in almost all eukaryotes. Human homolog of the scRev3 gene is located in chromosome region 6q21, and the mouse equivalent maps to chromosome 10, distal to the c-myb gene and close to the Macs gene. Alternative splicing, upstream out-of frame ATG can be found in yeast scRev3, mouse and human homologs. Furthermore, the sequence from 253-323 immediate upstream of the AUG initiator codon has the potential to form a stem-loop hairpin secondary structure in REV3 mRNA, suggesting that human REV3 protein may be expressed at low levels in human cells under normal growth conditions. The functional domain analysis showed that yeast Rev3-980 tyrosine in conserved region II is at the polymerase active site. Human REV3 amino acid residues 1 776-2 195 provide a REV7 binding domain, and REV7 amino acid residues 1-211 provide a bind domain for REV1, REV3 and REV7 itself. More interestingly, REV7 interacts with hMAD2 and therefore might function in the cell cycle control by affecting the activation of APC (anaphase promoting complex). Currently it has been known that pol zeta is involved in most spontaneous mutation, lesion-targeted mutation via TLS, chemical carcinogen induced untargeted mutation and somatic hypermutation of antibody genes in mammalian. In TLS pathway, pol zeta acts as a "mismatch extender" with combination of other DNA polymerases, such as pol iota. Unlike in yeast, it was found that pol zeta also functioned in mouse embryonic development more recently. It was hypothesized that the roles of pol zeta in TLS and cell cycle control might contribute to mouse embryonic lethality.

Animals↗

PubMed2003

[Assessment of the Escherichia coli Tat protein translocation system with fluorescent proteins].

The possibility of using fluorescent proteins as probes to study the twin-arginine translocation (Tat) system was assessed in Escherichia coli. When fused to the twin-arginine signal peptide of trimethylamine N-oxide reductase, the DsRed2 red fluorescent protein from the Discosoma sp. was successfully synthesized and folded in E. coli cells. However, RR-DsRed2 aggregated inside the cells. Therefore, although DsRed2 has been engineered from DsRed for faster maturation and lower non-specific aggregation, it is still not compatible with Tat-dependent translocation. In contrast, the jellyfish green fluorescent protein (GFP) was efficiently exported into periplasm even when the RR motif was changed to KR or RK. These results show that GFP can be used as an efficient reporter protein to study Tat system, but DsRed2 is not suitable for such purpose because of its aggregation property. In addition, when the protein concentration was similar, the fluorescence intensity of KR-GFP and RK-GFP decreased compared with RR-GFP, which would suggest that the twin-arginine signal peptide is not only essential for mediating protein translocation, but also important for the folding of down-stream protein.

Escherichia coli↗