PubMed Health⌕ Search

Biomedical subjects

Dong Zhang

Publications and source records attributed to Dong Zhang.

At least 73 records · Page 4Linked to original sources
PubMed2004

Localization of CD9 in pig oocytes and its effects on sperm-egg interaction.

CD9 is a cell surface protein that participates in many cellular processes, such as cell adhesion. Fertilization involves sperm and oocyte interactions including sperm binding to oocytes and sperm-oocyte fusion. Thus CD9 may play an essential role during fertilization in mammals. The present study was conducted to examine whether CD9 is present in porcine gametes and whether it participates in the regulation of sperm-oocyte interactions. The presence of CD9 in ovarian tissues, oocytes and spermatozoa was examined by immunohistochemistry, immunofluorescence and immunoblotting. Sperm binding and penetration of oocytes treated with CD9 antibody were examined by in vitro fertilization. The results showed that CD9 was present on the plasma membrane of oocytes at different developmental stages. A 24 kDa protein was found in oocytes during in vitro maturation by immunoblotting and its quantity was significantly (P < 0.001) increased as oocytes underwent maturation and reached the highest level after the oocytes had been cultured for 44 h. No positive CD9 staining was found in the spermatozoa. Both sperm binding to ooplasma and sperm penetration into oocytes were significantly (P < 0.01) reduced in anti-CD9 antibody-treated oocytes (1.2 +/- 0.2 per oocyte and 16.6% respectively) as compared with oocytes in the controls (2.5 +/- 0.4 per oocyte and 70.3% respectively). These results indicated that CD9 is expressed in pig oocytes during early growth and meiotic maturation and that it participates in sperm-oocyte interactions during fertilization.

Animals↗
PubMed2004

[Comparative study on the main biological characteristics of marrow-derived stromal cells and chondrocytes in vitro culture in rabbits].

OBJECTIVE: To observe the main biological characteristics and chondrogenesis potency of bone marrow-derived stromal cells (MSCs) after cytokines induction or gene modification in vitro. METHODS: MSCs from an adult New Zealand white rabbit were isolated and cultivated, and then MSCs were divided into the common medium group (Group A, 15% FBS in DMEM), the induced group by cytokines (Group B), the transfected group (Group C) with adenovirus-hepatocyte growth factor transgene (adHGF). The medium of group B consisted of transforming growth factor-beta 1 (TGF-beta 1, 10 ng/ml), basic fibroblast growth factor (bFGF, 25 ng/ml) and dexamethasone (DEX, 10(-7) mol/L) with 15%FBS in DMEM. Cartilage slices were obtained from femoral condyles and patellar grove in the same rabbit. The minced cartilage was digested in II collagenase (3 mg/ml) to obtain chondrocytes(Group D). The change of cell appearance, proliferation capacity, glycosaminoglycans (GAG), immunohistochemical staining for type I, II collagen were observed during the 5th passage MSCs and MSCs after induction or gene modification. Expression of mRNA for type I and II collagen was detected by RT-PCR. RESULTS: Primary MSCs proliferated as short-spindle shape, while the 5th MSCs showed long-spindle shape. Positive stain of type I collagen could be found in groups A, B and C, while positive stain of type II collagen was shown in groups B and D. The content of GAG in group B was higher than that in group A, but there was no significant difference between them (P > 0.05), and there was significant difference between groups A and D(P < 0.05). No significant difference was noted in groups A, B and C on proliferation by MTT(P > 0.05), except that of at the fourth day after transfection between groups A and C(P < 0.05). RT-PCR demonstrated that MSCs always had higher levels of mRNA type I collagen in groups A, B and C. The expression of mRNA type II collagen was identified in groups B and D, and only low levels of mRNA type II collagen in group C. CONCLUSION: The above results indicate MSCs have a natural tendency of osteogenic differentiation in vitro culture, and also demonstrate the chondrogenic potency with the technique of cytokines induction or gene modification after passage. MSCs can be transfected efficiently being seed cells in tissue engineered bone or cartilage to accept target genes such as adHGF, and have a higher levels of expression in vitro, which lasted 4 weeks at least.

Animals↗
PubMed2004

[Expression of human telomerase reverse transcriptase gene in HCC does not depend on proliferating cell nuclear antigen and P53].

AIM: To investigate the expression of human telomerase reverse transcriptase(hTERT) gene and its relationship with proliferating cell nuclear antigen and P53. METHODS: Immunohistochemical staining was used to detect the expressions of hTERT, PCNA and P53 in 42 hepatocellular carcinoma(HCC) tissues. The relationship between hTERT expression, pathological characters of HCC and PCNA and P53 expression was analyzed. RESULTS: The expression rates of hTERT, PCNA and P53 in HCC tissues were 71.4%(30/42),76.2%(32/42) and 73.8%(31/42), respectively. hTERT was not expressed in normal liver tissues. The expression rates of hTERT gene in HCC tissues of different pathological grades (I, II and III)were 40.0%(4/10), 70.0%(14/20) and 100%(12/12), respectively. The expression of hTERT was correlated with HCC recurrence. CONCLUSION: The expression of hTERT gene may relate to the genesis and progression of HCC. There is no significant correlation between the expression of hTERT and PCNA and P53. The detection of hTERT gene expression may be regarded as a marker for recurrence of HCC.

Aged↗
PubMed2004

[The establishment of an animal model of bilateral mandibular distraction osteogenesis in rabbits].

PURPOSE: To establish an animal model of bilateral mandibular distraction osteogenesis in rabbits. METHODS: 16 adult male white New Zealand rabbits were divided into 4 groups randomly, 4 in each group. Osteotomy was performed on mandible bilaterally before the first premolar. Bone stumps were repositioned and fixed with distractors. After 7 days of latency period, distraction was initiated at a rate of 1mm/d for 7 days. Then distractors were held in place for days. Animals were killed at different time points, and specimens were taken for X-ray and histology examination. RESULTS: The mandibles were lengthened successfully. The distraction gaps were filled with regenerated bone tissue. CONCLUSION: The method in this study is practicable and repeatable which could be used to establish an animal model of mandibular distraction osteogenesis in rabbits.

Animals↗
PubMed2003

Mapping susceptibility loci for alcohol consumption using number of grams of alcohol consumed per day as a phenotype measure.

BACKGROUND: There is substantial evidence for a significant genetic component to the risk for alcoholism. However, susceptibility loci or genes for alcohol dependence remain largely unknown. To identify susceptibility loci for alcohol dependence, we selected 329 extended families from the Framingham Heart Study population in which at least one family member reported alcohol consumption during the interview in 1970-1971, and performed genome-wide linkage analyses using various analytical methods. RESULTS: Multi-point sib-pair regression analysis using the SIBPAL program of S.A.G.E. provided strong evidence for linkage of alcohol dependence to chromosomes 9 (p-value < 0.0001) and weak evidence to chromosomes 15 and 16 (p-value < 0.005). To confirm these findings, we re-analyzed the same data set by various methods implemented in GENEHUNTER and found that only one region was significant with a LOD score > 2.0 by the variance-component method. This region is located on chromosome 9 between markers GATA21F05 and GATA81C04. CONCLUSION: Analyses of the Framingham Heart Study population provided evidence of genetic susceptibility loci for alcohol dependence on chromosomes 9, 15, and 16. The genomic region identified on chromosome 9 was particularly interesting because the region has also been previously reported to be linked to alcohol dependence in the American Indian population by another group.

Adult↗
PubMed2003

Hydrothermal syntheses, crystal structures, and magnetic properties of inorganic-organic hybrid vanadium selenites with zero- to three-dimensional structures: (1,10-phenanthroline)(2)V(2)SeO(7), (2,2'-bipyridine)VSeO(4), (4,4'-bipyridine)V(2)Se(2)O(8), and (4,4'-bipyridine)(2)V(4)Se(3)O(15).H(2)O.

A family of inorganic-organic hybrid vanadium selenites with zero-, one-, two-, and three-dimensional structures, (1,10-phen)(2)V(2)SeO(7), (2,2'-bipy)VSeO(4), (4,4'-bipy)V(2)Se(2)O(8), and (4,4'-bipy)(2)V(4)Se(3)O(15).H(2)O (where phen = phenanthroline and bipy = bipyridine), were hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Different bidentate organodiamine ligands and reactant concentrations were used in the four reaction systems, which are responsible for the variety of structural dimensions of the compounds. (1,10-phen)(2)V(2)SeO(7) crystallizes in a monoclinic system with space group P2(1)/n and cell parameters a = 8.6509(3) A,( )b = 7.8379(2) A, c = 34.0998(13) A, beta = 91.503(2) degrees, and Z = 4. (2,2'-bipy)VSeO(4) crystallizes in a monoclinic system with space group C2/c and cell parameters a = 17.0895(12) A, b = 14.7707(10) A, c = 11.7657(8) A, beta = 131.354(3) degrees, and Z = 8. (4,4'-bipy)V(2)Se(2)O(8) crystallizes in a triclinic system with space group Ponemacr; and cell parameters a = 7.1810(10) A, b = 10.8937(13) A, c = 11.1811(15) A, alpha = 115.455(3) degrees, beta = 107.582(3) degrees, gamma = 91.957(4) degrees, and Z = 2. (4,4'-bipy)(2)V(4)Se(3)O(15).H(2)O crystallizes in a monoclinic system with space group Pc and cell parameters a = 7.9889(9) A, b = 7.8448 A, c = 23.048(3) A, beta = 99.389(4) degrees, and Z = 2. (1,10-phen)(2)V(2)SeO(7) has an isolated structure, (2,2'-bipy)VSeO(4) has a chain structure, (4,4'-bipy)V(2)Se(2)O(8) has a layered structure, and (4,4'-bipy)(2)V(4)Se(3)O(15).H(2)O has a framework structure. The chains are constructed from VO(4)N(2) octahedra and SeO(3) pyramids, laced by organic ligands (2,2'-bipy). The layers consist of vanadium selenite chains [(VO)(2)(SeO(3))(2)]( infinity ), linked by 4,4'-bipy molecules. The framework is composed of vanadium selenite sheets [V(4)Se(3)O(16)]( infinity ), pillared by 4,4'-bipy molecules. All of the compounds are thermally stable to 300 degrees C, and the magnetic susceptibilities confirm the existence of tetravalent V atoms in the antiferromagnetic (4,4'-bipy)V(2)Se(2)O(8) complex and mixed tetravalent and pentavalent V atoms in the paramagnetic complex (4,4'-bipy)(2)V(4)Se(3)O(15).H(2)O.

Journal Article↗
PubMed2003

Versatile photosensitization system for 1O2-mediated oxidation of alkenes based on nafion-supported platinum(II) terpyridyl acetylide complex.

[structure: see text] Platinum(II) terpyridyl acetylide complex (1) was incorporated into Nafion membranes as a photosensitizer, and the Nafion was immersed in an aqueous or organic solution of 7-dehydrocholesterol, alpha-pinene, or cyclopentadiene. This photosensitizer system can generate singlet oxygen ((1)O(2)) in high quantum yield to oxidize the alkenes in the solution outside the Nafion and can be easily removed from the reaction vessel at the end of the photooxidation.

Journal Article↗
PubMed2003

A fragment of anthrax lethal factor delivers proteins to the cytosol without requiring protective antigen.

Anthrax protective antigen (PA) is a 735-aa polypeptide that facilitates the exit of anthrax lethal factor (LF) from the endosome to the cytosol where the toxin acts. We recently found, however, that a fusion protein of the detoxified N-terminal domain of lethal factor (LFn) with a foreign peptide could induce CD8 T cell immune responses in the absence of PA. Because CD8 T cells recognize peptides derived from proteins degraded in the cytosol, this result suggests that lethal factor may be capable of entering the cytosol independently of PA. To investigate this further, the intracellular trafficking of an LFn-enhanced green fluorescent protein fusion protein (LFn-GFP) in the presence or absence of PA was examined by using confocal microscopy. LFn-GFP is able to enter the cytosol without PA. Moreover, it efficiently colocalizes with the proteosome 20s subunit, which degrades proteins into peptides for presentation to CD8 T cells by the MHC class I pathway. We further demonstrate that in the presence of an immune adjuvant LFn fusion protein without PA is able to effectively elicit anti-HIV cytotoxic T lymphocyte in inbred mice. These results indicate that LFn may be used without PA in a protein vaccine as a carrier to deliver antigens into the cytosol for efficient induction of T lymphocyte responses. Furthermore, these results enable us to propose a modified molecular mechanism of anthrax lethal toxin.

Animals↗
PubMed2003

A vanadium(IV) phosphite with a pillared layered structure: hydrothermal synthesis and characterization of (VO)4(4,4'-bpy)2(HPO3)4.

A novel vanadium(IV) phosphite, (VO)(4)(4,4'-bpy)(2)(HPO(3))(4), was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the monoclinic system with the space group C2/c and cell parameters a = 35.970(3) A, b = 15.9400(13) A, c = 10.7681(7) A, beta = 101.073(4) degrees, and Z = 8 with R(1) = 0.0482. The structure of the compound consists of trigonal bipyramidal [VO(4)N] and pseudopyramidal [HPO(3)] blocks, which are connected by corner-sharing, to form vanadium phosphite layers in the bc plane. These layers are further linked through 4,4'-bpy pillars, generating a 3D framework. Thermogravimetric analysis and magnetic susceptibility data for this compound are given.

Journal Article↗
PubMed2003

Tumor suppressor NM23-H1 is a granzyme A-activated DNase during CTL-mediated apoptosis, and the nucleosome assembly protein SET is its inhibitor.

Granzyme A (GzmA) induces a caspase-independent cell death pathway characterized by single-stranded DNA nicks and other features of apoptosis. A GzmA-activated DNase (GAAD) is in an ER associated complex containing pp32 and the GzmA substrates SET, HMG-2, and Ape1. We show that GAAD is NM23-H1, a nucleoside diphosphate kinase implicated in suppression of tumor metastasis, and its specific inhibitor (IGAAD) is SET. NM23-H1 binds to SET and is released from inhibition by GzmA cleavage of SET. After GzmA loading or CTL attack, SET and NM23-H1 translocate to the nucleus and SET is degraded, allowing NM23-H1 to nick chromosomal DNA. GzmA-treated cells with silenced NM23-H1 expression are resistant to GzmA-mediated DNA damage and cytolysis, while cells overexpressing NM23-H1 are more sensitive.

Active Transport, Cell Nucleus↗
PubMed2003

Hydrothermal syntheses and crystal structures of complex-linked three-Dimensional coordination vanadium selenites: M(4,4'-bipy)(H(2)O)V(2)Se(2)O(10) (M = Co, Ni).

Two inorganic-organic hybrid compounds with the formula M(4,4'-bipy)(H(2)O)V(2)Se(2)O(10) (M = Co, Ni) were hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compounds Co(4,4'-bipy)(H(2)O)V(2)Se(2)O(10) (1) and Ni(4,4'-bipy)(H(2)O)V(2)Se(2)O(10) (2), which are structural analogues, crystallize in the triclinic space group Ponemacr; with crystal data a = 7.9665(3) A, b = 8.1974(3) A, c = 13.8096(4) A, alpha = 85.704(2) degrees, beta = 73.5180(10) degrees, gamma = 75.645(2) degrees, V = 837.76(5) A(3), and Z = 2 and a = 7.9489(19) A, b = 8.128(2) A, c = 13.709 A, alpha = 85.838(6) degrees, beta = 73.736(8) degrees, gamma = 75.594(9) degrees, V = 823.5(4) A(3), and Z = 2, respectively. [M(4,4'-bipy)(H(2)O)V(2)Se(2)O(10)] (M = Co, Ni) have a three-dimensional structure and consist of two subunits, [(VO(2))(SeO(3))](-) infinite chains and [M(4,4'-bipy)(H(2)O)](2+) fragments. The [(VO(2))(SeO(3))](-) chains are composed of [V(2)Se(4)O(14)](4)(-) clusters linked by VO(4)N triangular bipyramids. The 4,4'-bipy molecule as a bifunctional organic ligand is directly linked to Co or Ni and V atoms, affording the three-dimensionality. The compounds were characterized by infrared spectroscopy and differential thermal and thermogravimetric analyses.

Journal Article↗
PubMed2003

Cleaving the oxidative repair protein Ape1 enhances cell death mediated by granzyme A.

The cytolytic T lymphocyte protease granzyme A (GzmA) initiates a caspase-independent cell death pathway. Here we report that the rate-limiting enzyme of DNA base excision repair, apurinic endonuclease-1 (Ape1), which is also known as redox factor-1 (Ref-1), binds to GzmA and is contained in the SET complex, a macromolecular complex of 270-420 kDa that is associated with the endoplasmic reticulum and is targeted by GzmA during cell-mediated death. GzmA cleaves Ape1 after Lys31 and destroys its known oxidative repair functions. In so doing, GzmA may block cellular repair and force apoptosis. In support of this, cells with silenced Ape1 expression are more sensitive, whereas cells overexpressing noncleavable Ape1 are more resistant, to GzmA-mediated death.

Animals↗
PubMed2003

Isolation and culture of embryonic stem cells from porcine blastocysts.

This study was conducted to establish embryonic stem (ES) cell lines from porcine blastocysts. Blastocysts were collected from China miniature pigs at day 7-9 of pregnancy. Embryos were either directly (intact embryos) cultured on mitomysin C-inactivated murine embryonic fibroblasts (MEF) as feeder layers, or were used to isolate the inner cell masses (ICM) by enzyme digestive method and then cultured. It was found that enzyme digestive method could isolate ICMs without any damages of cells in all blastocysts (28). All ICMs attached to the feeder layers. Primary cell colonies were formed in 68% of ICM culture and 28% of intact blastocyst culture. Two ES cell lines derived from ICM passed six subcultures (passages). These cells morphologically resembled mouse ES cells and consistently expressed alkaline phosphatase activity. When the ES cells were cultured in a medium without feeder layer and leukemin inhibitory factor, they differentiated into several types of cells including neuron-like, smooth muscle-like, and epithelium-like cells. Some cells formed embryoid bodies in a suspension culture. These results indicate that porcine ES cell line can be established under the present experimental conditions and these ES cells are pluripotent.

Alkaline Phosphatase↗
PubMed2003

Theoretical calculation and experimental study on the third-order nonlinearity parameter C/A for organic liquids and biological fluids.

In the present paper we deal with calculating and measuring the third-order nonlinearity parameter C/A for organic liquids and biological fluids. For the organic liquids, the second-order derivative of sound speed with respect to pressure at constant entropy is discussed in terms of thermodynamic parameters, and a formula for calculating C/A is established. Calculated results of C/A for various organic liquids demonstrate that omitting the second-order derivative of sound speed with respect to sound pressure in an isentropic process, could overestimate the value of C/A about 20%-30%. For measuring C/A, the finite-amplitude insert substitution technique is employed. A theoretical description of the sound pressure amplitude for the third-order harmonics is obtained using the perturbation method, in which the sound pressure amplitude of the third-order harmonics is shown approximately as a parabolic function of the propagation distance in the medium. By measuring and comparing the sound pressure amplitudes of the third-order harmonics when inserting a test sample, the reference liquid, and a comparative liquid, respectively, the value of C/A for the sample liquid is determined with reference to known C/A values of reference and comparative liquids. An experimental setup is developed, and the measured values of C/A for the organic liquids agree with the predicted ones calculated by the thermodynamic methods. Furthermore, the finite-amplitude method is extended to measure the C/A parameter for biological fluids, and the measured values of C/A for several biological fluids are also presented.

Body Fluids↗
PubMed2003

Sustained small interfering RNA-mediated human immunodeficiency virus type 1 inhibition in primary macrophages.

Small interfering RNAs (siRNAs) can induce potent gene silencing by degradation of cognate mRNA. However, in dividing cells, the silencing lasts only 3 to 7 days, presumably because of siRNA dilution with cell division. Here, we investigated if sustained siRNA-mediated silencing of human immunodeficiency virus type 1 (HIV-1) is possible in terminally differentiated macrophages, which constitute an important reservoir of HIV in vivo. CCR5, the major HIV-1 coreceptor in macrophages, and the viral structural gene for p24 were targeted either singly or in combination. When transfected 2 days prior to infection, both CCR5 and p24 siRNAs effectively reduced HIV-1 infection for the entire 15-day period of observation, and combined targeting of both genes abolished infection. To investigate whether exogenously introduced siRNA is maintained stably in macrophages, we tested the kinetics of siRNA-mediated viral inhibition by initiating infections at various times (2 to 15 days) after transfection with CCR5 and p24 siRNAs. HIV suppression mediated by viral p24 siRNA progressively decreased and was lost by day 7 posttransfection. In contrast, viral inhibition by cellular CCR5 knockdown was sustained even when transfection preceded infection by 15 days, suggesting that the continued presence of target RNA may be needed for persistence of siRNA. The longer sustenance of CCR5 relative to p24 siRNA in uninfected macrophages was also confirmed by detection of internalized siRNA by modified Northern blot analysis. We also tested the potential of p24 siRNA to stably silence HIV in the setting of an established infection where the viral target gene is actively transcribed. Under these circumstances, long-term suppression of HIV replication could be achieved with p24 siRNA. Thus, siRNAs can induce potent and long-lasting HIV inhibition in nondividing cells such as macrophages.

Antiviral Agents↗
PubMed2003

Measuring the performance of screening mammography in community practice with Medicare claims data.

BACKGROUND: Few studies have examined the outcomes of screening mammography in community practice, particularly the extent of false positive exams among older asymptomatic women. RESEARCH DESIGN: Subjects were female Medicare beneficiaries, age 67 or older, residing in one of eleven SEER areas, with no evidence of breast cancer. Medicare claims data were used to identify their screening mammograms over two time periods, 1993-1995 and 1996-1998, and to measure their use of follow-up diagnostic testing (diagnostic mammography, breast ultrasound and breast biopsy) within three months of the screening mammogram. RESULTS: There were significant differences among the rates of diagnostic testing for each age group (67-74; 75+ ) by year, but no clear trend toward higher or lower rates over time. Although rates of diagnostic testing differed significantly by geographic region in both time periods 1993-1995 and 1996-1998, estimates of specificity for all regions were within AHRQ clinical practice guidelines (specificity greater than 90%). Specificity significantly improved with the volume of the radiologist's practice for the latter time period (1996-1998) but not for the former (1993-1995). CONCLUSION: Medicare claims offer an accessible population-based source of data for mammography performance indicators. As such, they offer a low cost method for evaluating individual mammography practices as well as monitoring the impact of reimbursement policies, practice guidelines and laws mandating requirements for accrediting facilities.

Aged↗
PubMed2003

Pathological observation of brain arteries and spontaneous aneurysms in hypertensive rats.

OBJECTIVE: To investigate the role of hypertension in the pathogenesis of cerebral aneurysms in rats. METHODS: Twenty spontaneous hypertensive rats (SHR) and 10 Wistar-Kyoto rats (WKY) were included in this observational study. Animals were fed with normal diet and drinking water. No experimental modifications were undertaken in either group. They were sacrificed at one year of age, the bifurcations of the circle of Willis were dissected and longitudinal serial sections were prepared for light microscopic and transmission electron microscopic study. RESULTS: In the SHR group, 2 of the 20 rats formed an aneurysm respectively at the bifurcations of the basilar artery. As revealed by electron microscopy, injury at the bifurcation of the artery first occurred on the steeper side of the intimal pad. Furthermore, loss of endothelial cells, small depressions on the intima, disruptive internal elastic lamina and lymphocytes or red blood cells infiltration were noted at the steeper side of the intimal pad. No significant changes were observed in WKY group. CONCLUSIONS: Cerebral aneurysms can form spontaneously in SHR without ligation of the common carotid artery and without a diet containing beta-aminoproprionitrile. Long-standing systemic arterial hypertension is one of the etiological factors that contributes to aneurysm formation in SHR rats.

Animals↗