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Biomedical subjects

Yi Zhao

Publications and source records attributed to Yi Zhao.

At least 91 records · Page 5Linked to original sources
PubMed2003

Multi-functional sorbents for the simultaneous removal of sulfur and lead compounds from hot flue gases.

A multi-functional sorbent is developed for the simultaneous removal of PbCl(2) vapor and sulfur dioxide from the combustion gases. The sorbent is tested in a bench-scale reactor at the temperature of 700 degrees C, using simulated flue gas (SFG) containing controlled amounts of PbCl(2) and SO(2) compounds. The removal characteristics of PbCl(2) and SO(2), individually and in combination, are investigated. The results show that the mechanism of capture by the sorbent is not a simple physical adsorption process but seems to involve a chemical reaction between the Ca-based sorbent and the contaminants from the simulated flue gas. The porous product layer in the case of individual SO(2) sorption is in a molten state at the reaction temperature. In contrast, the combined sorption of lead and sulfur compounds generates a flower-shaped polycrystalline product layer.

Adsorption↗
PubMed2003

Genetic analysis of Nurr1 haplotypes in Parkinson's disease.

Nurr1 gene plays an important role in the development of the mesencephalic dopaminergic system. Genetic variability of Nurr1 gene may be associated with risk of Parkinson's disease (PD). We found three polymorphic loci (c.-2922(C)2-3, IVS6+18insG and EX8+657 (9-10CA)) of the Nurr1 gene in our PD patients and a novel intron 7+33 C-->T variant in one PD patient. We proceeded to perform a haplotype analysis in a case control study. A total of 202 PD patients (mean age 65.04+/-9.44 years, 55.4% men) and 202 age, gender and race matched controls (mean age 64.33+/-10.12 years, 54.0% men) were studied. The intron 7+33 C-->T variant was present in only one of the PD patients (0.5%) but in none of the controls. The Nurr1 mRNA levels in the lymphocytes did not significantly differ between the affected patient and controls. We found complete linkage disequilibrium between c.-2922(C)2-3 and IVS6+18insG polymorphic loci (D=0.25). Analysis of the three loci haplotype frequencies did not demonstrate any significant difference between PD and controls. There were also no significant differences in the haplotype frequencies between young and late onset PD patients. In conclusion, we demonstrated a large common haplotype block spanning the Nurr1 gene in our population. The intron 7+33 C-->T variant most likely represents either a non-functional mutation or a rare polymorphism in our study population. Our study suggests that Nurr1 variability is unlikely to play a major role in the majority of our PD patients.

DNA-Binding Proteins↗
PubMed2003

Adenomatous polyposis coli (APC)-independent regulation of beta-catenin degradation via a retinoid X receptor-mediated pathway.

Beta-catenin is a component of stable cell adherent complexes whereas its free form functions as a transcription factor that regulate genes involved in oncogenesis and metastasis. Free beta-catenin is eliminated by two adenomatous polyposis coli (APC)-dependent proteasomal degradation pathways regulated by glycogen synthase kinase 3beta (GSK3 beta) or p53-inducible Siah-1. Dysregulation of beta-catenin turnover consequent to mutations in critical genes of the APC-dependent pathways is implicated in cancers such as colorectal cancer. We have identified a novel retinoid X receptor (RXR)-mediated APC-independent pathway in the regulation of beta-catenin. In this proteasomal pathway, RXR agonists induce degradation of beta-catenin and RXR alpha and repress beta-catenin-mediated transcription. In vivo, beta-catenin interacts with RXR alpha in the absence of ligand, but RXR agonists enhanced the interaction. RXR agonist action was not impaired by GSK3 beta inhibitors or deletion of the GSK3 beta-targeted sequence from beta-catenin. In APC- and p53-mutated colorectal cancer cells, RXR agonists still inactivated endogenous beta-catenin via RXR alpha. Interestingly, deletion of the RXR alpha A/B region abolished ligand-induced beta-catenin degradation but not RXR alpha-mediated transactivation. RXR alpha-mediated inactivation of oncogenic beta-catenin paralleled a reduction in cell proliferation. These results suggest a potential role for RXR and its agonists in the regulation of beta-catenin turnover and related biological events.

Adenomatous Polyposis Coli↗
PubMed2003

Effects of heme addition on formation of stable human globin chains and hemoglobin subunit assembly in a cell-free system.

Our previous assembly studies to form hemoglobin hetero-dimers and -tetramers using a coupled transcription/translation cell-free system suggested that alpha-globin chains bind to nascent non-alpha chains during and/or soon after translation to promote hemoglobin formation [Adachi et al., J. Biol Chem. 2002 (277) 13415]. In this report effects of CN-hemin on subunit assembly were studied using this cell-free system. Addition of CN-hemin and excess unlabeled heme-containing partner chains during synthesis leads to formation of radiolabeled heme-containing alpha(h)beta(h) hetero-dimers. In contrast, in the absence of added CN-hemin, unlabeled heme-containing alpha or beta chains can assemble with newly synthesized radiolabeled beta- and alpha-globin chains to form heme-containing alpha(h)beta(h) and semi-alpha (alpha(h)beta(0)) or semi-beta (alpha(0)beta(h)) hetero-dimers, respectively. These results suggest the existence of semi-hemoglobins as intermediates prior to formation of heme-containing alpha(h)beta(h) and indicate transfer of heme from alpha and/or beta chains into semi-hemoglobin hetero-dimers to form heme-containing hetero-dimers.

Cell-Free System↗
PubMed2003

Topological structure analysis of the protein-protein interaction network in budding yeast.

Interaction detection methods have led to the discovery of thousands of interactions between proteins, and discerning relevance within large-scale data sets is important to present-day biology. Here, a spectral method derived from graph theory was introduced to uncover hidden topological structures (i.e. quasi-cliques and quasi-bipartites) of complicated protein-protein interaction networks. Our analyses suggest that these hidden topological structures consist of biologically relevant functional groups. This result motivates a new method to predict the function of uncharacterized proteins based on the classification of known proteins within topological structures. Using this spectral analysis method, 48 quasi-cliques and six quasi-bipartites were isolated from a network involving 11,855 interactions among 2617 proteins in budding yeast, and 76 uncharacterized proteins were assigned functions.

Algorithms↗
PubMed2003

Alpha synuclein promoter and risk of Parkinson's disease: microsatellite and allelic size variability.

Polymorphism of the alpha synuclein promoter region (non-amyloid component of plaques (NACP)-Rep1) is associated with an increased risk of Parkinson's disease (PD) in three separate studies. We studied NACP-Rep1 polymorphism in two independent case control studies in our population. In study one, 104 PD and 104 age, gender and race matched controls; and in study two, 102 PD and 102 age, gender and race matched controls were examined separately. The results of both studies were analyzed independent of one another. We found three polymorphic alleles (designated 0, 1, 2). In study one, the frequency of allele 2 was significantly higher in PD patients as compared to healthy controls (0.37 versus 0.23, P=0.01, X(2)=9.98). In study two, the frequency of allele 2 was similar between PD and controls (0.31 versus 0.33, P=1.00, X(2)=0.30). There was a non-significant higher allele 2 frequency in PD when both studies were analyzed together (0.34 versus 0.28, P=0.20, X(2)=3.4). No significant differences of the various genotypes between PD and controls were found. However there were differences of the mixed dinucleotide repeats sequences for similar homozygous genotypes. Variability of the microsatellite region and potential interacting factors that could affect alpha synuclein gene transcription should be further examined.

Adult↗
PubMed2003

Dopamine D2 receptor TaqIA and TaqIB polymorphisms in Parkinson's disease.

In a case control study, we examined the association of DRD2 Taq1A and Taq1B polymorphisms and risk of PD, and evaluated the strength of linkage disequilibrium of the polymorphisms. The Taq1A and Taq1B polymorphisms were in strong linkage disequilibrium. There was, however, no significant association of the two polymorphisms with PD.

Alleles↗
PubMed2003

Hepatic venoplasty in right lobe live donor liver transplantation.

Inclusion of the middle hepatic vein (MHV) in a right lobe graft is essential to guarantee uniform venous drainage and optimum function of the graft, but end-to-end recipient-to-donor MHV anastomosis may result in outflow obstruction. To avoid outflow obstruction, we designed the venoplasty technique. From September 2000 to November 2002, 65 adult patients received right lobe live donor liver transplantation (LDLT) with grafts containing the right hepatic vein (RHV) and MHV. In the first 34 recipients, the graft RHV and MHV were anastomosed to the recipients' RHV and MHV/left hepatic vein, respectively. For the subsequent 31 recipients, the MHV was joined to the RHV at the back table to form a triangular common orifice. The septum in between the two hepatic veins was divided at the middle and sutured transversely to remove the ridge in between and to create a large opening. The common orifice was anastomosed to a matched-size triangular opening in the recipient's inferior vena cava. After reperfusion, the presence of triphasic pulsatility on spectral Doppler tracing was regarded as a sign of perfect reconstruction. In the first group, Doppler study showed little flow in the MHV in 3 patients, absent pulsatility in the MHV after portal vein reperfusion in 4 patients, and absent pulsatility in the MHV after hepatic artery reperfusion in 5 patients. In the second group, excellent triphasic pulsatility was seen in all except 1 patient (12 of 34 versus 1 of 31, P =.001). A significant increase in the peak flow velocity was seen in the MHV in the second group (median, 19.45 cm/sec versus 31.4 cm/sec, P<.001). Less time was required to complete the hepatic vein anastomoses in the second group (40 minutes versus 27 minutes, P<.001). In conclusion, hepatic venoplasty technique facilitates the implantation of the right lobe graft and guarantees outflow in the MHV.

Adolescent↗
PubMed2003

Contribution of bradykinin and nitric oxide to AT2 receptor-mediated differentiation in PC12 W cells.

We investigated the effect of angiotensin II on intracellular cyclic GMP content and neurite outgrowth as an indicator of cell differentiation in PC12 W cells. Neurite outgrowth was examined by phase-contrast microscopy. Outgrown neurites were classified as small, medium and large, and were expressed as neurites per 100 cells. Angiotensin II (10-7 m) increased the outgrowth of medium and large neurites by mean +/- SEM 20.2 +/- 2.3 and 6.6 +/- 1.4 compared with 1.66 +/- 0.5 and 0.1 +/- 0.06 neurites per 100 cells in control. Cellular cyclic GMP content increased by 50-250% with angiotensin II at concentrations of 10-6-10-4 m. Both blockade of AT2 receptors and of nitric oxide synthase markedly reduced angiotensin II-induced neurite outgrowth and cyclic GMP production. In contrast, B2 receptor blockade had no effect or even increased these angiotensin II effects. Sodium nitroprusside and 8-bromo-cyclic GMP both mimicked the effects of angiotensin II on cell differentiation. The protein kinase G inhibitor KT-5823 inhibited the neurite outgrowth induced by both angiotensin II and 8-bromo-cyclic GMP. Our results demonstrate that angiotensin II can stimulate cell differentiation in PC12 W cells by nitric oxide-related and cyclic GMP-dependent mechanisms. The effects of angiotensin II on cell differentiation and cyclic GMP production were mediated via the AT2 receptor and further enhanced by bradykinin B2 receptor blockade.

Alkaloids↗
PubMed2003

Experimental and mechanism studies on seawater flue gas desulfurization.

Seawater flue gas desulfurization (Seawater FGD) process has a number of advantages, but the study on mechanism of seawater FGD is little. The effects of absorbing efficiency of SO2 by the constant component and part of trace transition elements in seawater are studied by the experiment. The results indicate that the effect factors of absorption of SO% by seawater are alkaline, ion intensity, catalysis of Cl- and transition metal ions Fe2+ Mn(2+). The degree of effect is alkaline > the catalysis of Cl-, Fe2+ and Mn2+ > ion intensity. The mechanisms of catalysis oxidation for S( IV) by Cl -, Fe2+ and Mn2 are discussed. According to the results, some measures can be used to improve the capability of desulfurization.

Absorption↗
PubMed2003

Hydrological adjustment and flooding control of wetlands in the Liaohe Delta.

The function of estuary wetland on hydrological adjustment and flooding control is studied in this paper. It is estimated that the evapotranspiration in the reed field during growth season (June to October) is 722.9 mm, which is 37.5% higher than large water body (E601: 525.9 mm). The water replacement rate in the reed field can reach 95% only when the rains continuously for 11 days and the precipitation reached 912 mm. For the water balance in the paddy field, the total water requirement ranges between 1920 and 1860 mm, among which, 31% is from precipitation, and the left is provided by reservoirs. The water usage efficiency is 0.35 at present productivity. Based on the landscape characteristics and functionalities on flooding control, 5 functional zones are designed for the Liaohe Delta; key protected area; underground storage area; flooding discharge area; flood diversion area in emergency; and flood control drainage area.

China↗
PubMed2003

[Inhibitory effect of dendritic cells induced activated cytotoxicity T lymphocyte combined with MAGE-1 nonapeptide on transplanted human hepatocyte carcinoma in nude mice].

OBJECTIVE: To observe the inhibitory effect of dendritic cells (DCs) activated cytotoxicity T lymphocyte (CTL) combined with MAGE-1 nonapeptide on transplanted human hepatocyte carcinoma (HCC) in nude mice. METHODS: A model of HCC transplanted tumor was established by injecting BEL-7402 cell line HCC cells subcutaneously on the back of nude mice. Successful transplantation rate was 73%. Specific CTLs (1 x 10(6)), which were activated by DCs combined with MAGE-1 nonapeptide, were injected into the site of transplanted tumor (group A, n = 5). Another group of 17 mice were treated with same amounts of different kinds of cells, and they were divided into groups B, C, D, E, and F. The growth of tumor was observed, and pathological examination was also done. RESULTS: (1) The activated lymphocytes induced by DCs combined with MAGE-1 nonapeptide could suppress the growth of tumor and reduce the tumor size. In group A, 5/5 mice survived for at least two weeks, while the tumors grew rapidly and the majority of the mice died within two weeks in other groups (groups B, C, D, E, F) (P < 0.01). (2) Extensive necrosis and apoptosis were found in transplanted tumors in group A. CONCLUSIONS: The DCs combined with MAGE-1 nonapeptide could not only inhibit the growth of HCC, but also result in produce death and apoptosis of HCC, hence preventing tumor metastasis and recurrence. The mechanism underlying tumor immunization resulted from DCs might be enhanced in apoptosis of tumor cells. MAGE-1 nonapeptide combined with DCs might be a potential novel tumor vaccine for the treatment of HCC.

Animals↗
PubMed2003

[Study on controlling the blood glucose level of gestational diabetes mellitus sufferer regularly during labor].

OBJECTIVE: To study the maternal blood glucose management of gestational diabetes mellitus during the labor and relationship of maternal blood glucose in labor and neonatal blood sugar. METHODS: A prospective study on maternal blood glucose monitoring and control during labor was carried in 40 pregnant women with abnormal glucose metabolism. We adjusted maternal blood glucose by low-dosage constant insulin drop during labor. RESULTS: Maternal blood glucose in labor arranged between 3.8 approximately 11.2 mmol/L, and low-dosage constant insulin drop was used in 17 cases (42.5%). The neonatal blood glucose was (4.0 +/- 1.5) mmol/L following delivery and (3.9 +/- 1.0) mmol/L at 24-hour postpartum. There were 2 cases with neonatal hypoglycemia. The neonatal blood glucose of the rest 23 cases was (4.2 +/- 1.5) mmol/L, and (3.9 +/- 1.0) mmol/L at 24-hour postpartum, and 1 case with neonatal hypoglycemia. There was no the difference of the blood glucose level of newborns between mothers with abnormal glucose metabolism and the normal pregnant women. CONCLUSION: It is necessary to monitor and control the blood glucose level by low dose constant insulin during labor in pregnant women with abnormal glucose metabolism.

Adult↗
PubMed2002

Murine hematopoietic stem cell distribution and proliferation in ablated and nonablated bone marrow transplantation.

The engraftment of donor bone marrow (BM) cells in nonablated mice is inefficient. Niche availability has been thought to be the reason, and cytoablation with irradiation or cytotoxic agents is routinely used with the belief that this frees the preoccupied niches in recipients. In this study, donor cell redistribution and proliferation in ablated and nonablated mice were compared by implanting donor cells directly into the femur cavity of sedated mice. The redistribution of Lin(-) donor cells into BM was similar between ablated and nonablated mice. Poor engraftment in nonablated mice was shown to be the result of inefficient donor cell proliferation rather than because of a lack of space. Competitive repopulation assays demonstrated that the donor hematopoietic stem cells (HSCs) were present in nonirradiated recipients for at least 6 months after transplantation, but that they did not expand as did their counterparts in lethally irradiated mice. This study suggests that efficient bone marrow transplantation in nonablated recipients may be possible as a result of better understanding of HSC proliferative regulation and appropriate in vitro manipulation.

Animals↗
PubMed2002

Transduction of long-term-engrafting human hematopoietic stem cells by retroviral vectors.

Gene therapy using retroviral vectors to transfer functional exogenous genes into hematopoietic stem cells (HSCs) promises to provide a permanent cure for a wide array of both hematopoietic and nonhematopoietic disorders by virtue of the fact that retroviral vectors permanently integrate into the host cell genome and HSCs are able to self-renew and give rise to differentiated progeny throughout the life span of the patient. However, for transduction and genomic integration to occur, the target cells must undergo cell division and express the appropriate retroviral receptor, requirements that have thus far hindered attempts at inserting exogenous genes into human HSCs in vitro. In the present studies, we used the fetal sheep xenograft model of human hematopoiesis to evaluate whether human long-term engrafting HSCs could be transduced in vivo, within a fetal microenvironment. We transplanted adult human bone marrow-derived CD34(+)Lin(-) cells into preimmune fetal sheep recipients and subsequently (19 days later) administered clinical-grade murine retroviral vector supernatants to these fetal hematopoietic chimeras. Our results demonstrate that this approach successfully transduced adult human HSCs within all seven sheep that survived the procedure, and that these transduced HSCs had the ability to serially engraft primary, secondary, and tertiary fetal sheep recipients. Transgene expression persisted throughout the serial transplantation. The successful in vivo transduction of long-term engrafting human HSCs with the existing generation of murine retroviral vectors has significant implications for developing new approaches to pre- and postnatal gene therapy.

Antigens, CD34↗
PubMed2002

Assembly of human hemoglobin (Hb) beta- and gamma-globin chains expressed in a cell-free system with alpha-globin chains to form Hb A and Hb F.

Rates of in vitro synthesis of radiolabeled gamma and beta chains made in a cell-free transcription/translation system were similar, but expressed globin chains were unstable. The addition of unlabeled beta or gamma chains at the start of chain synthesis generated radiolabeled beta(4) or gamma(2) and gamma(4) chains, respectively. If unlabeled alpha-globin chains were added at the start of chain synthesis, then approximately equal amounts of radiolabeled alphabeta or alphagamma bands were generated. If unlabeled Hb A or Hb F was added to reactions containing radiolabeled alphabeta or alphagamma prior to electrophoresis, then radiolabeled Hb A or Hb F tetramers, respectively, were generated. If alpha chains were added after synthesis of radiolabeled gamma chains made in the presence of unlabeled gamma chains, then little radiolabeled alphagamma formed. In contrast, if alpha chains were added after synthesis of radiolabeled beta chains made in the presence of unlabeled beta chains, then radiolabeled alpha(2)beta(2) formed. These findings suggest that beta and gamma chains associate with alpha chains during or soon after translation. This would prevent the formation of unstable monomers as well as stable gamma(2) dimers and suggests that alpha chains may bind to nascent non-alpha chains, acting as folding catalysts to promote functional tetrameric hemoglobin formation in vivo.

Cell-Free System↗
PubMed2002

Identification of a zinc finger homoeodomain enhancer protein after AT(2) receptor stimulation by differential mRNA display.

Using differential mRNA display, we isolated differentially expressed genes after stimulation of angiotensin II (Ang II) type 2 (AT(2)) receptors in PC12w cells. Among the polymerase chain reaction products isolated, we identified Zfhep, a zinc finger homoeodomain enhancer-binding protein and the angiotensin AT(2) receptor itself, both implicated in developmental processes. In the presence of epidermal growth factor (EGF) a concordant expression pattern of Zfhep and AT(2) mRNA was observed with marked downregulation 6 hours after stimulation with EGF+Ang II. In quiescent PC12w cells, Zfhep mRNA was time-dependently induced by Ang II (10(-7) mol/L) up to 3 hours, an effect that was blocked by the selective AT(2) antagonist PD123177 (10(-6) mol/L). We extended our studies on Zfhep mRNA expression to cells of vascular origin (coronary endothelial cells [CECs]), that express AT(1) and AT(2) receptors, and that respond differently to Ang II dependent on which receptor subtype is stimulated. In CECs, Zfhep mRNA expression was induced up to 3 hours after AT(2) stimulation. Interestingly, this Zfhep induction was observed only when the AT(1) receptor was blocked by using the selective AT(1) receptor antagonist, losartan (10(-5) mol/L), suggesting a negative-regulatory influence of AT(1) receptors on AT(2)-induced Zfhep mRNA induction. In conclusion, Zfhep not only represents a suitable marker for AT(2) receptor activation, but it may also link AT(2) signaling and downstream events involved in the proposed function of the AT(2) receptor in development and regeneration.

Angiotensin Receptor Antagonists↗