[A case of the recurrent left atrial mignant tibrous histocytome].
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Female↗
Biomedical subjects
X M Zhang
Publications and source records attributed to X M Zhang.
Synthetic antigenic decapeptides of human brain acetylcholinesterase cross-immunoreact with peptide-specific antibodies against Torpediniformes narcine timlei acetylcholinesterase.
Antigenic decapeptides of human brain acetylcholinesterase (AChE) were investigated for immunoreactivity with the rabbit anti-Torpediniformes narcine timlei AChE polyclonal antibody (anti-narcine AChE polyclonal antibody). The decapeptides were synthesized using the multipin combinatorial chemical synthesis technique and biotinylated at N-terminals. Rabbit anti-narcine AChE polyclonal antibodies were purified by Protein A-Sepharose CL 4B column chromatography. Enzyme-linked immunosorbent assay (ELISA) was used for the assay of the reaction between the antigen and the antibody. Seven of 11 antigenic synthetic decapeptides of human brain AChE showed obvious immunoreactivity with the rabbit anti-narcine AChE polyclonal antibodies. The similarity of the AChE sequences of humans and Torpedo species were compared thereby with the epitopes indicated. The results indicate that the epitopes of human brain AChE and Torpedo AChEs have been highly conserved during evolution. In view of this, no N-glycosylation site was found in the antigenic decapeptides tested, they all belong to oligopeptide epitopes.
Acetylcholinesterase↗
Microdialysis measurement of ascorbic acid in rabbit vitreous after photodynamic reaction.
A method for long-term intravitreous microdialysis was used to measure endogenous reduced ascorbic acid in the vitreous of rabbits by HPLC-ECD before and after exposure to intense visible light in the presence of fluorescein. Cellulose microdialysis probes were implanted into the vitreous humor of each eye and after stabilization ascorbic acid measurements were recorded over a 14 day period. Under this experimental condition, normal ascorbic acid concentrations in vitreous varied from 98.0 +/- 9.8 to 106.9 +/- 20.3 microM(mean +/- S.D.). The eyes received light irradiation (25 000 lux) for 2 hr and fluorescein was used as the photosensitizer once or twice. No immediate effects on ascorbic acid concentrations could be observed in the eyes irradiated twice without fluorescein i.v. injections and in the twice fluorescein injected without irradiation. However, in the eyes irradiated once with fluorescein (30 mg kg(-1)), ascorbic acid concentration after irradiation significantly decreased from day 2 and continued over a period of 10 days compared with that before irradiation and maximal reduction was 32.6% (P < 0.005) on day 6 after irradiation. By day 13, the ascorbic acid concentration returned to control levels (P > 0.01). In the eyes irradiated twice with fluorescein injections, ascorbic acid concentration after irradiation decreased even more over the experimental period and the maximal reduction was 65.5% (P < 0.005) on day 5 after irradiation and did not recover over the next 9 days. In the eyes irradiated twice with fluorescein injections plus administration of ascorbic acid (150 mg kg(-1)) 30 min before irradiation, a significant increase (52.5%) of ascorbic acid (P < 0.005) was found on day 1 and control levels of ascorbic acid were maintained from day 2 onward. The protective role of ascorbic acid in the vitreous humor against photodynamic reaction is suggested.
Animals↗
Immortalized multipotential mesenchymal cells and the hematopoietic microenvironment.
In an attempt to analyze the cellular and molecular basis of the capacity of bone marrow stromal cells to support hematopoiesis in culture, we developed a series of murine stromal cell lines from a single long-term bone marrow culture (BMC). The cytokines produced by these cells were analyzed using immunohistochemical techniques, ribonuclease protection assays (RPA) and RT-PCR. We examined the capacity of these cloned cell lines to replace primary bone marrow-derived stromal cells in long-term bone marrow cultures (LT-BMC) and sought correlations between the capacity to support hematopoiesis in culture with the production of known cytokines. These immortalized lines replicate many of the functions of the hematopoietic microenvironment. They express cytokines known to play a role in hematopoiesis. All of the lines constitutively express mRNA for PBSF (SDF-1), macrophage colony-stimulating factor (M-CSF), stem cell factor (SCF), FLT-3, thrombopoietin (TPO), interleukin 7 (IL-7), leukemia inhibitory factor (LIF), tumor necrosis factor-beta (TNF-beta), and interferon-gamma (IFN-gamma). Most lines also express granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF. They vary in their expression of IL-6, tumor growth factor-beta1 (TGF-beta1), TGF-beta2, and TNF-alpha. Growing these lines in the presence of cytokines that influence hematopoiesis alters the levels of cytokine message. The most striking effects were produced by TNF-alpha. In addition to the cytokine mRNAs, the cell lines express factors associated with bone formation such as osteoblast-specific factor-2 (OSF-2) and bone morphogenetic protein-1 (BMP-1). They also express the neural cell-adhesion molecule neuropilin and neurotrophic factors including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). Several of the lines can maintain hematopoiesis in culture, as measured by the continuous production of myeloid colony-forming cells (CFU-c), for months. This capacity to support hematopoiesis does not correlate with any pattern of cytokine expression. Several of these lines also support the growth of human hematopoietic cells, and human CFU-c can be detected in the cultures in which CD34(+) bone marrow cells (BMC) are cultured on murine stromal cells. No correlation between the production of any of the known cytokines and the ability to support murine hematopoiesis was detected. In addition, there was no correlation between the capacity to support murine hematopoiesis and the capacity to maintain human HSC. Despite repeated cloning, the lines remain heterogeneous and are capable of producing cells with the properties of fibroblasts, osteoblasts, adipocytes, and myoblasts. In addition to the cytokine mRNAs, the cell lines express factors associated with bone formation such as OSF-2 and BMP-1. They also express the neural cell-adhesion molecule neuropilin and neurotrophic factors including NGF and BDNF.
Animals↗
Metastatic melanoma cells escape from immunosurveillance through the novel mechanism of releasing nitric oxide to induce dysfunction of immunocytes.
Nitric oxide (NO) is known to facilitate tumour metastasis through the promotion of angiogenesis, vascular dilation, platelet aggregation, etc. In the present study we explored its novel role in producing dysfunction of the host immune system in the metastasis of murine metastatic melanoma B16-BL6 cells. A significant reduction in the mixed lymphocyte reaction (MLR) was observed in the spleen cells from B16-BL6-bearing mice, but not in those from mice bearing the parent cell B16. When B16-BL6 cells were added in vitro to the MLR, a significant decrease was also found, even when they were co-cultured with the lymphocytes in two compartments of a Transwell chamber separated by an 8.0 microm filter. The supernatant from cultured B16-BL6 but not B16 cells, which had a greatly increased NO activity, significantly inhibited concanavalin A- and lipopolysaccharide-induced lymphocyte proliferation. A remarkably higher expression of inducible NO synthase (iNOS) was detected in B16-BL6 cells than in B16 cells. Nomega-Nitro-l-arginine (l-NNA), a NO synthase inhibitor and superoxide dismutase, significantly antagonized the above inhibition by B16-BL6 cells, while l-arginine, a NO precursor, and S-nitroso-N-acetyl-d,l-penicillamine, a NO donor, strengthened the inhibition. Furthermore, l-NNA significantly inhibited lung metastasis of B16-BL6 cells, while l-arginine tended to enhance the metastasis. The cytotoxicity of B16-BL6-specific T-cells was significantly decreased by pre-culture with B16-BL6 cells in a Transwell chamber or the culture supernatants of B16-BL6 cells, whereas l-iminoethyl-lysine, a selective inhibitor of iNOS, showed a significant recovery from the disease. These results suggest that NO released by metastatic tumour cells may impair the immune system, which facilitates the escape from immunosurveillance and metastasis of tumour cells.
Animals↗
Rapid MR imaging detection of renal cysts: age-based standards.
PURPOSE: To establish age-based standards for renal cysts depicted at magnetic resonance (MR) imaging and to compare these standards with existing standards for ultrasonography (US). MATERIALS AND METHODS: Three radiologists reviewed subsecond T2-weighted single-shot fast spin-echo kidney MR imaging findings in 528 patients (248 men, 280 women) selected from consecutive abdominal MR studies without regard to clinical indication. Age, sex, and number and diameter of cysts were noted. Results were analyzed with nonparametric tests and were compared with published US results. RESULTS: Men (mean, 2.0; 95% CI: 1.5, 2.5) had more renal cysts than women (mean, 1.2; 95% CI: 0.9, 1.5) (P < .001). Number and diameter of cysts increased with age (P < .001). Of 528 patients, 330 (62.5%) had at least one renal cyst, and 315 (59.7%) had cysts of 10 mm or less. MR imaging findings were comparable to published US criteria for type 1 autosomal dominant polycystic kidney disease (ADPKD) if only cysts larger than 1 cm were considered: Only one subject in the group of 18-29-year-old subjects had at least two renal cysts, and five of 493 subjects aged 30-59 years had at least two cysts in each kidney. CONCLUSION: Compared with reported US results, MR imaging depicted an increased number of simple renal cysts in healthy individuals because of its increased sensitivity for cysts smaller than 1 cm. If only simple renal cysts larger than 1 cm are considered, US criteria for type 1 ADPKD can be applied to MR imaging.
Adolescent↗
Genetic manipulation of hedgehog signaling in the endochondral skeleton reveals a direct role in the regulation of chondrocyte proliferation.
Indian hedgehog (Ihh), one of the three mammalian hedgehog (Hh) proteins, coordinates proliferation and differentiation of chondrocytes during endochondral bone development. Smoothened (Smo) is a transmembrane protein that transduces all Hh signals. In order to discern the direct versus indirect roles of Ihh in cartilage development, we have used the Cre-loxP approach to remove Smo activity specifically in chondrocytes. Animals generated by this means develop shorter long bones when compared to wild-type littermates. In contrast to Ihh mutants (Ihh(n)/Ihh(n)), chondrocyte differentiation proceeds normally. However, like Ihh(n)/Ihh(n) mice, proliferation of chondrocytes is reduced by about 50%, supporting a direct role for Ihh in the regulation of chondrocyte proliferation. Moreover, by overexpressing either Ihh or a constitutively active Smo allele (Smo*) specifically in the cartilage using the bigenic UAS-Gal4 system, we demonstrate that activation of the Ihh signaling pathway is sufficient to promote chondrocyte proliferation. Finally, expression of cyclin D1 is markedly downregulated when either Ihh or Smo activity is removed from chondrocytes, indicating that Ihh regulates chondrocyte proliferation at least in part by modulating the transcription of cyclin D1. Taken together, the present study establishes Ihh as a key mitogen in the endochondral skeleton.
Animals↗
Regulation of retinal ganglion cell production by Sonic hedgehog.
Previous work has shown that production of retinal ganglion cells is in part regulated by inhibitory factors secreted by ganglion cell themselves; however, the identities of these molecules are not known. Recent studies have demonstrated that the signaling molecule Sonic hedgehog (Shh) secreted by differentiated retinal ganglion cells is required to promote the progression of ganglion cell differentiation wave front and to induce its own expression. We present evidence that Shh signals play a role to negatively regulate ganglion cell genesis behind the differentiation wave front. Higher levels of Shh expression are detected behind the wave front as ganglion cells accumulate, while the Patched 1 receptor of Shh is expressed in adjacent retinal progenitor cells. Retroviral-mediated overexpression of Shh results in reduced ganglion cell proportions in vivo and in vitro. Conversely, inhibiting endogenous Shh activity by anti-Shh antibodies leads to an increased production of ganglion cells. Shh signals modulate ganglion cell production within the normal period of ganglion cell genesis in vitro without significantly affecting cell proliferation or cell death. Moreover, Shh signaling affects progenitor cell specification towards the ganglion cell fate during or soon after their last mitotic cycle. Thus, Shh derived from differentiated ganglion cells serves as a negative regulator behind the differentiation wave front to control ganglion cell genesis from the competent progenitor pool. Based on these results and other recent findings, we propose that Shh signals secreted by early-differentiated retinal neurons play dual roles at distinct concentration thresholds to orchestrate the progression of retinal neurogenic wave and the emergence of new neurons.
Animals↗
[The distribution and homology of mitochondrial plasmid-like DNAs in different cucumber varieties].
Four kinds of mitochondrial plasmid-like DNA, designated pC1, pC2, pC3 and pC4, have been found in cucumber (Jinyan No. 4). Their distribution in 14 Cucumber varieties was analyzed. Plasmid-like DNAs were detected in Jinchun No. 2, Jinchun No. 5, Jinxinmici, Jinlu No. 4 and Jinyan No. 4, and the rest 9 varieties contained no plasmid-like DNAs, suggesting that their distribution is irregular. There was homology among the same plasmid-like DNA family in different varieties. pC4 showed homology to the nuclear DNA of Jinyan No. 4, in addition to the nuclear genomes of other 7 varieties either with plasmid-like DNAs or without. The homologous sequences of pC4 in the cucumber nuclear DNA were repetitive. Sequences homologous to pC4 were also found in the nuclear genomes of towel gourd and pumpkin (other cucurbitaceous plant). Therefore, we propose that mitochondrial plasmid-like DNA occurred before cucumber diverged from cucurbit and had integrated into the nuclear DNA. The varieties without plasmid-like DNAs might lost them during evolution.
Cucumis sativus↗
Concentrative phenomenon of relative content ratios of Cu, Pb and Zn in soils.
It is discovered that there is the concentrative phenomenon of relative content ratios of Cu, Pb and Zn in soil by studying their parageneous association in soil, meteorites and rocks with the relative content ratios. This not only is helpful to understand the trends of Cu, Cd and Zn enriched and dispersed in the evolution course of earth matter, but also provides evidence for geochemical self-organization that there may be in the process of Cu, Pb and Zn translation and distribution.
China↗
Stimulation by melittin of Na+-Ca2+ exchange current in ventricular myocytes of guinea pigs.
AIM: To study the mechanism of calcium overload induced by melittin in myocytes. METHODS: Whole cell patch-clamp technique was applied for recording the currents. RESULTS: Mel 0.05, 0.1 micromol/L increased the peak amplitude of I(Na) (nA) from -2.1+/-0.8 to -3.2+/-1.0 (n=7, P < 0.05) and -3.7+/-1.5 (n=7, P < 0.05) respectively at testing potential of -40 mV. Mel 0.05, 0.1, 0.2 micromol/L had no significant effect on I(Ca), but enhanced I(Na-Ca) (pA) from 53+/-21 to 427+/-256 (n=5, P < 0.05), 349+/-147 (n=5, P<0.01) and 320+/-97 (n=5, P < 0.05) respectively at a testing potential of +50 mV. CONCLUSION: The stimulating effect of Mel on I(Na-Ca) rather than the effect on I(Ca) contributes to the calcium overload of myocytes.
Animals↗
Inhibitory effect of melittin on Na+,K+-ATPase from guinea pig myocardial mitochondria.
AIM: To investigate the effect of melittin (Mel) of Na+,K+-ATPase activity and it's kinetic mode of action on guinea pig myocardial mitochondria. METHODS: Effect of Mel on heart mitochondrial Na+,K+-ATPase activity was determined with colorimetry method. RESULTS: Mel inhibited Na+,K+-ATPase in a concentration and time dependent manner, IC50 was 2.60 micromol/L. Kinetic studies of interaction between Mel and K+, Na+, ATP revealed that inhibitory effect of Mel was competitive with K+, but not with Na+ and ATP. CONCLUSION: Mel polypeptide potently inhibits Na+,K+-ATPase, possibly by binding to the K+ site.
Animals↗
Effects of endothelin receptor A antagonist FR139317 on rats with congestive heart failure.
AIM: To study the effects of a selective endothelin receptor A (ETA) antagonist FR139317 on rats with congestive heart failure. METHODS: A congestive heart failure model was established via left coronary artery ligation in adult male Wistar rats. The rats with congestive heart failure were treated with FR139317 at two doses (1 and 5 mg . kg-1 . d-1 respectively for 6 weeks) or with vehicle. Hemodynamics, plasma level of endothelin-1 (ET-1), and mortality rate of rats were measured. RESULTS: Both groups treated with FR139317 (high and low dose) have lower mortality rate (25.0 % and 28.6 % vs 50.0 %) and lower plasma level of ET-1 than that of vehicle [(3.6 +/- 1.2) ng/L and (4.9 +/- 1.5) ng/L vs (5.8 +/- 1.3) ng/L]. Comparing to vehicle group, left ventricular end-diastolic pressures of the FR139317-treated groups were improved significantly [(12 +/- 6) mmHg and (14 +/- 7) mmHg vs (22 +/- 9) mmHg]. FR139317 at a higher dose reduced the mean arterial pressure of the rats with congestive heart failure and decreased the plasma concentration of endothelin to a closer level of rats with normal heart function than lower dose. CONCLUSION: Selective ETA antagonist FR139317 improved the hemodynamics and reduced the plasma ET-1 level and the mortality of rats with congestive heart failure
Animals↗
[Screening and sequence analysis of the adult stage-specific gene of Trichinella spiralis].
OBJECTIVE: To obtain the sequence of the adult stage-specific gene of Trichinella spiralis. METHODS: An adult T. spiralis cDNA library was screened using an adult T. spiralis stage-specific probe. The gene sequence was analyzed by DNAstar software and GenBank database. RESULTS: A cDNA clone of 1,629 bp was obtained by screening the library with an adult stage-specific probe. The clone contained one open reading frame composed of 1,464 bp encoding 487 amino acids. GenBank searching revealed that no identical cDNA was found. Two zinc fingers located at the positions within amino acids 207-270. Some possible antigen epitopes were predicted within the amino acids 52-64, 108-116, 137-163 and 226-260. CONCLUSION: A novel stage-specific gene of adult T. spiralis encoding the protein containing certain predicted antigen epitopes was obtained.
Amino Acid Sequence↗
[Genotypes of merozoite surface protein 2 of Plasmodium falciparum in different malaria endemic areas].
OBJECTIVE: To determine the genotypes and distribution of MSP2 of Plasmodium falciparum isolates in Yunnan and Hainan provinces, China. METHODS: The central polymorphic region of MSP2 allele was amplified by the nested PCR for genotyping of P. falciparum. RESULTS: The higher degree of polymorphism of MSP2 of P. falciparum was observed in Yunnan and Hainan. Distribution and allele frequencies differed in both provinces, indicating considerable geographical heterogeneity of parasite populations. The mixed infection of different allele-type and multiplicity of infection was more frequent in Hainan than in Yunnan. CONCLUSION: There were obvious differences in the distribution and frequencies of MSP2 alleles between Yunnan and Hainan endemic areas. MSP2 is suitable to be used as a marker gene for the genotyping of P. falciparum infection.
Alleles↗
Maturation of vulnerability to excitotoxicity: intracellular mechanisms in cultured postnatal hippocampal neurons.
Neuronal vulnerability to excitotoxicity changes dramatically during postnatal maturation. To study the intracellular mechanisms by which maturation alters vulnerability in single neurons, we developed techniques to maintain hippocampal neurons from postnatal rats in vitro. After establishing their neuronal phenotype with immunohistochemistry and electrophysiology, we determined that these neurons exhibit developmentally regulated vulnerability to excitotoxicity. At 5 days in vitro, NMDA-induced cell death at 24 h increased from 3.6% in 3-day-old rats to >90% in rats older than 21 days. Time-lapse imaging of neuronal morphology following NMDA demonstrated increasingly prevalent and severe injury as a function of postnatal age. Neither high- nor low-affinity calcium dyes demonstrated differences in peak NMDA-induced [Ca(2+)](i) increases between neurons from younger and older animals. However, neurons from older animals were uniformly distinguished from those from younger animals by their subsequent loss of [Ca(2+)](i) homeostasis. Because of the role of mitochondrial Ca(2+) buffering in [Ca(2+)](i) homeostasis, we measured NMDA-induced changes in mitochondrial membrane potential (DeltaPsi) as a function of postnatal age. NMDA markedly dissipated DeltaPsi in neurons from mature rats, but minimally in those from younger rats. These data demonstrate that, in cultures of postnatal hippocampal neurons, (a) vulnerability to excitotoxicity increases as a function of the postnatal age of the animal from which they were harvested, and (b) developmental regulation of vulnerability to NMDA occurs at the level of the mitochondrion.
Aging↗
Apoptosis of Mo7e leukemia cells is associated with the cleavage of Bcl-2 into a shortened fragment that is not functional for heterodimerization with Bcl-2 and Bax.
Bcl-2 is an integral intracellular membrane protein that can protect cells from apoptosis induced by multiple insults in a variety of cell types. During apoptosis, Bcl-2 was cleaved into a shortened fragment (Bcl-2/Delta34) by a caspase-3-like protease in human Mo7e megakaryocytic leukemia cells deprived of exogenous rhGM-CSF. Results from cell fractionation and immunoblot analyses indicated that both Bcl-2 and Bcl-2/Delta34 were located exclusively on the mitochondria of Mo7e cells. Treatment of isolated mitochondria with recombinant caspase-3 induced the same cleavage of Bcl-2 in vitro and caused the release of cytochrome c from the mitochondria into the supernatant. The antiapoptotic effect of Bcl-2/Delta34 was investigated using an in vitro protein translation approach. Both Bcl-2/Delta34 and Bax proteins generated in wheat germ extract were readily relocated to the mitochondria isolated from control Mo7e cells. Insertion of Bax, but not Bcl-2/Delta34, into mitochondria triggered a rapid release of cytochrome c from the mitochondria. Coimmunoprecipitation studies showed that, unlike Bcl-2, the cleaved Bcl-2 fragment was no longer functional for dimerization with either Bcl-2 or Bax. Taken together, these findings showed that the integrity of Bcl-2 is necessary for its function of heterodimerization with Bax, which appears to be one of the mechanisms of antiapoptotic effect of Bcl-2.
Apoptosis↗
Hematopoietic progenitor cells grow on 3T3 fibroblast monolayers that overexpress growth arrest-specific gene-6 (GAS6).
Pluripotential hematopoietic stem cells grow in close association with bone marrow stromal cells, which play a critical role in sustaining hematopoiesis in long-term bone marrow cultures. The mechanisms through which stromal cells act to support pluripotential hematopoietic stem cells are largely unknown. This study demonstrates that growth arrest-specific gene-6 (GAS6) plays an important role in this process. GAS6 is a ligand for the Axl (Ufo/Ark), Sky (Dtk/Tyro3/Rse/Brt/Tif), and Mer (Eyk) family of tyrosine kinase receptors and binds to these receptors via tandem G domains at its C terminus. After translation, GAS6 moves to the lumen of the endoplasmic reticulum, where it is extensively gamma-carboxylated. The carboxylation process is vitamin K dependent, and current evidence suggests that GAS6 must be gamma-carboxylated to bind and activate any of the cognate tyrosine kinase receptors. Here, we show that expression of GAS6 is highly correlated with the capacity of bone marrow stromal cells to support hematopoiesis in culture. Nonsupportive stromal cell lines express little to no GAS6, whereas supportive cell lines express high levels of GAS6. Transfection of the cDNA encoding GAS6 into 3T3 fibroblasts is sufficient to render this previously nonsupportive cell line capable of supporting long-term hematopoietic cultures. 3T3 cells, genetically engineered to stably express GAS6 (GAS6-3T3), produce a stromal layer that supports the generation of colony-forming units in culture (CFU-c) for up to 6 wk. Hematopoietic support by genetically engineered 3T3 is not vitamin K dependent, and soluble recombinant GAS6 does not substitute for coculturing the hematopoietic progenitors with genetically modified 3T3 cells.
3T3 Cells↗