Biomedical subjects

Yuzhen Zhang

Publications and source records attributed to Yuzhen Zhang.

13 recordsLinked to original sources

PubMed2007

GATA and Nkx factors synergistically regulate tissue-specific gene expression and development in vivo.

In vitro studies have suggested that members of the GATA and Nkx transcription factor families physically interact, and synergistically activate pulmonary epithelial- and cardiac-gene promoters. However, the relevance of this synergy has not been demonstrated in vivo. We show that Gata6-Titf1 (Gata6-Nkx2.1) double heterozygous (G6-Nkx DH) embryos and mice have severe defects in pulmonary epithelial differentiation and distal airway development, as well as reduced phospholipid production. The defects in G6-Nkx DH embryos and mice are similar to those observed in human neonates with respiratory distress syndromes, including bronchopulmonary dysplasia, and differential gene expression analysis reveals essential developmental pathways requiring synergistic regulation by both Gata6 and Titf1 (Nkx2.1). These studies indicate that Gata6 and Nkx2.1 act in a synergistic manner to direct pulmonary epithelial differentiation and development in vivo, providing direct evidence that interactions between these two transcription factor families are crucial for the development of the tissues in which they are co-expressed.

Alleles↗

PubMed2006

Hop functions downstream of Nkx2.1 and GATA6 to mediate HDAC-dependent negative regulation of pulmonary gene expression.

Hop is an unusual homeodomain protein that was first identified in the developing heart where it functions downstream of Nkx2.5 to modulate cardiac gene expression. Hop functions through interactions with histone deacetylase (HDAC) 2 to mediate repression of cardiac-specific genes, and recent studies show that HDAC activity and HDAC2 expression are decreased in people with chronic obstructive pulmonary disease. Here, we show that Hop is expressed in airway epithelium coincident with HDAC2, and expression is induced by the combination of dexamethasone and cAMP in parallel with induction of surfactant protein gene expression. Hop functions in the developing pulmonary airway, acting downstream of Nkx2.1 and GATA6, to negatively regulate surfactant protein expression. Loss of Hop expression in vivo results in defective type 2 pneumocyte development with increased surfactant production and disrupted alveolar formation. Thus Hop represents a novel regulator of pulmonary maturation that is induced by glucocorticoids to mediate functionally important HDAC-dependent negative feedback regulation.

Animals↗

PubMed2006

Assessment of management practices in a small agricultural watershed in Southeast China.

In this study, an event-based agricultural non-point source pollution model (AGNPS) was calibrated and validated in an agricultural watershed in Southeast China. The AGNPS predicted runoff, peak runoff rate, nitrogen and phosphorus well matched the observed value during calibration and validation. The validated model was then applied to simulate performance of the two existed management practices and three alternative scenarios using current management practices as background losses of non-point source (NPS) pollutants. Simulations showed that the existed management practices (contour cultivation and multi-pond system) were very effective in reduction of nutrient losses. Although alternative practices, such as improved nutrient management, conversions of current orchards to woods, and their combined practices, certainly reduced the NPS pollutants from the watershed, a detailed cost-benefit analysis is necessary to select practices that could be implemented for further reduction of agricultural NPS pollutants.

Agriculture↗

PubMed2005

Recombinant nucleoprotein-based serological diagnosis of Crimean-Congo hemorrhagic fever virus infections.

An enzyme-linked immunosorbent assay (ELISA) using recombinant nucleoprotein (rNP) was reported for the detection of immunoglobulin G (IgG) antibodies to Crimean-Congo hemorrhagic fever (CCHF) virus (CCHFV). The immunoglobulin M (IgM)-capture ELISA was developed for the diagnosis of CCHFV infections, using CCHFV rNP as an antigen. These newly developed assays were applied to a study of a CCHF-outbreak and evaluated with sera collected from patients diagnosed as having CCHF by positive reverse transcription-polymerase chain reaction (RT-PCR) and by detection of IgG response. IgM antibodies to CCHFV were detected in 10 of the 13 patients. IgM antibodies to the rNP of CCHFV were detected by the CCHFV rNP-based IgM-capture ELISA in all 6 patients in whom IgG responses were demonstrated, while it was not detected in the 10 patients in whom IgG responses were not demonstrated. Furthermore, the IgM antibodies were detected in 6 of the 61 residents living a CCHF endemic area during the endemic season, while it was not detected in any of the 48 Japanese residents that had never visited the CCHF endemic area. It is concluded that this newly developed CCHFV rNP-based IgM-capture ELISA is a useful method for the diagnosis of CCHFV infections.

Adolescent↗

PubMed2005

Antigen-capture enzyme-linked immunosorbent assay for the diagnosis of crimean-congo hemorrhagic fever using a novel monoclonal antibody.

An antigen-capture enzyme-linked immunosorbent assay (ELISA) was developed for the diagnosis of Crimean-Congo hemorrhagic fever (CCHF) using a novel monoclonal antibody, 1B7, to the recombinant nucleoprotein (rNP) of CCHF virus (CCHFV) Chinese strain 8402. This ELISA detected at least 2 ng/100 microl of CCHFV rNP of 8402 and of the Nigeria strain Ibr 10200, and also detected authentic nucleoproteins (NP) of Chinese strains. Although the sensitivity of the ELISA was lower than that of nested reverse transcription polymerase chain reaction (RT-PCR), it was able to detect nucleoproteins in acute sera of CCHF patients. The presence of anti-CCHFV IgG decreased the sensitivity of the ELISA, possibly due to competition with 1B7, and this would tend to limit application of the ELISA. However, the method may be useful for the diagnosis of CCHF patients in the acute stage of illness, especially in laboratories not equipped with RT-PCR testing capabilities.

Animals↗

PubMed2004

Isoleucine biosynthesis in Leptospira interrogans serotype lai strain 56601 proceeds via a threonine-independent pathway.

Three leuA-like protein-coding sequences were identified in Leptospira interrogans. One of these, the cimA gene, was shown to encode citramalate synthase (EC 4.1.3.-). The other two encoded alpha-isopropylmalate synthase (EC 4.1.3.12). Expressed in Escherichia coli, the citramalate synthase was purified and characterized. Although its activity was relatively low, it was strictly specific for pyruvate as the keto acid substrate. Unlike the citramalate synthase of the thermophile Methanococcus jannaschii, the L. interrogans enzyme is temperature sensitive but exhibits a much lower K(m) (0.04 mM) for pyruvate. The reaction product was characterized as (R)-citramalate, and the proposed beta-methyl-d-malate pathway was further confirmed by demonstrating that citraconate was the substrate for the following reaction. This alternative pathway for isoleucine biosynthesis from pyruvate was analyzed both in vitro by assays of leptospiral isopropylmalate isomerase (EC 4.2.1.33) and beta-isopropylmalate dehydrogenase (EC 1.1.1.85) in E. coli extracts bearing the corresponding clones and in vivo by complementation of E. coli ilvA, leuC/D, and leuB mutants. Thus, the existence of a leucine-like pathway for isoleucine biosynthesis in L. interrogans under physiological conditions was unequivocally proven. Significant variations in either the enzymatic activities or mRNA levels of the cimA and leuA genes were detected in L. interrogans grown on minimal medium supplemented with different levels of the corresponding amino acids or in cells grown on serum-containing rich medium. The similarity of this metabolic pathway in leptospires and archaea is consistent with the evolutionarily primitive status of the eubacterial spirochetes.

2-Isopropylmalate Synthase↗

PubMed2004

Possible horizontal transmission of crimean-congo hemorrhagic Fever virus from a mother to her child.

The case of a child with Crimean-Congo hemorrhagic fever (CCHF) presumably infected with CCHF virus from her 27-year-old mother is described. The mother with CCHF was treated with ribavirin and did not present with any symptoms of obvious hemorrhage. The child developed fever on the 5th day after the mother's onset. The partial virus genome was amplified by RT-PCR, and nested PCR from the child and the genome sequence were identical to that from the mother, indicating possible transmission of the virus from mother to child. This case indicates the importance of preventive measures for in-house outbreaks of CCHF.

Adult↗

PubMed2003

Identification and characterization of rodent ABCA1 in isolated type II pneumocytes.

ATP-binding cassette transporter A1 (ABCA1) promotes transfer of cholesterol and phospholipid from cells to lipid-free serum apolipoproteins. ABCA1 mRNA and protein expression in primary cultures of rodent type II cells was sensitive to upregulation with 5 microM 9-cis-retinoic acid (9cRA) and 6.2 microM 22-hydroxycholesterol (22-OH). The increase in ABCA1 protein levels was time dependent and was maximal after 16 h of exposure to 9cRA + 22-OH. Inducible ABCA1 was also found in transformed cell lines of lung origin: WI38/VA13, A549, and NIH-H441 cells. Stimulation of ABCA1 in rat type II cells by 9cRA + 22-OH resulted in a four- or fivefold enhancement of efflux of radioactive phospholipid or cholesterol, respectively, from the pneumocytes to apolipoprotein AI (apo AI), whereas cAMP (0.3 mM) had no effect. ABCA1-mediated lipid efflux to apo AI was independent of the surfactant secretion pathway, inasmuch as upregulation of ABCA1 resulted in a reduction of secretagogue-stimulated surfactant phospholipid release. These studies demonstrate the presence of functional ABCA1 in type II cells from the lung.

ATP Binding Cassette Transporter 1↗

PubMed2003

A patient with Crimean-Congo hemorrhagic fever serologically diagnosed by recombinant nucleoprotein-based antibody detection systems.

We treated a male patient with Crimean-Congo hemorrhagic fever (CCHF). The diagnosis of CCHF was confirmed by reverse transcription-PCR and recombinant nucleoprotein (rNP)-based immunoglobulin G (IgG) and IgM capture enzyme-linked immunosorbent assays of serially collected serum samples. The patient was treated with intravenous ribavirin and recovered with no consequences. The study indicates that rNP-based CCHF virus antibody detection systems are useful for confirming CCHF virus infections. This case also suggests that intravenous ribavirin therapy may be promising for the treatment of CCHF patients.

Adult↗

PubMed2003

[Purification and some properties of bacteriolytic enzyme R1 from Streptomyces griseus RX-17].

Bacteriolytic enzyme R1 was purified to electrophoretic homogeneity with the recovery of 6.89% activity by ammonium sulfate precipitation, CM-Sephadex C - 50, CM-Sepharose Fast Flow and Sephadex G-75 chromatography from the culture supernatant of Streptomyces griseus RX-17. The molecular weight and PI of R1 were 16.8 kD and 9.10. The optimal temperature and pH for R1 against Streptococcus mutans Ingbritt were 70 degrees C and 6.6, respectively. Below 50 degrees C and at range pH 6 - 10, R1 was stable. While treated at 60 degrees C for 1 hour, the residual activity was only about 20.3%. Zn2+, Cu2+, Fe2+, Cd2+ and Pb2+ could completely inactivate the enzyme. Chelating agents, hydroxylamine hydrochloriae, Monoiodoacetic acid inhibited the lytic activity against Streptococcus mutans Ingbritt, whereas Mg2+, 2-Mercaptoethanol and some surfactants could stimulate the activity. The enzyme had a broad bacteriolytic spectrum against many G+, G- bacteria which were resistant to egg-white lysozyme. Especially high activity was shown on Streptococcus mutans, Staphylococcus aureus and Lactobaillus.

Bacteria↗

PubMed2002

Dual mechanism of action of amlodipine in human vascular smooth muscle cells.

OBJECTIVES: It has been recently shown that calcium channel blockers (CCBs) could also control smooth muscle cell (SMC) growth/reactivity through mechanisms that were unrelated to their CCB property. Here, we investigated the effects of amlodipine and isradipine on Ca2+ movements and p42/p44 mitogen-activated protein kinase (ERK 1/2) activities, which are two early signalling events triggered by growth factors such as thrombin and basic fibroblast growth factor (bFGF). METHODS: In cultured human SMCs isolated from internal mammary arteries, Ca2+ movements and ERK 1/2 activation were studied by measurement of the intracellular Ca2+ concentration in Fura 2-labelled SMCs and by Western blots, respectively. RESULTS: In thrombin- and thapsigargin-stimulated SMCs, amlodipine and not isradipine dose-dependently reduced Ca2+ mobilization (i.e. Ca2+ release from internal stores); these dihydropyridines did not affect either Ca2+ influx or ERK 1/2 activation. In bFGF-stimulated SMCs, amlodipine and isradipine reduced both Ca2+ influx and ERK 1/2 activation without affecting Ca2+ mobilization. ERK 1/2 activation could also be directly stimulated by the l-type channel agonist Bay K 8644, demonstrating the involvement of voltage-gated Ca2+ influx in this process. Most of the observed effects described were obtained with approximately 10 nmol/l amlodipine/isradipine (i.e. concentrations close to the peak plasma level in treated patients). CONCLUSIONS: In human SMCs, amlodipine can (i) specifically alter Ca2+ mobilization, likely by interacting with the sarcoplasmic reticulum and (ii) inhibit voltage-dependent Ca2+ influx and the resulting ERK 1/2 activation. It is likely that amlodipine exerts its growth-inhibitory potency by interfering with multiple branches of mitogenic signalling pathways.

Amlodipine↗

PubMed2002

Study on the correlation between tongue size and openbite.

OBJECTIVE: To investigate the correlation between tongue size and openbite. METHODS: The tongue size of the openbite patients and the subjects with normal occlusion was measured by B-type ultrasonic imaging respectively. The tongue size of the openbite patients and the subjects with normal occlusion was compared. RESULTS: The tongue size in openbite group was larger than in normal occlusion group. The difference was statistically significant. CONCLUSIONS: Tongue size was related to the openbite.

Adolescent↗

PubMedDate not supplied

Anthropogenic nitrogen sources and exports in a village-scale catchment in Southeast China.

An experimental village-scale catchment was selected for investigation of nitrogen (N) sources and exports. The mean N application rate over the catchment was 350.2 kg N ha(-1), but this rate varied spatially and temporally. The N leaching loss rate varied from 8.1 to 52.7 kg N ha(-1) under different land use regimes. The average N leaching loss rate was 13.4 kg N ha(-1) over the whole catchment, representing about 3.8% of the total N inputs. The N export rate through stormflows was 28.8 kg N ha(-1), about 8.2% of the total N inputs. Seasonal patterns showed that 95% of N exports through stormflows occurred during July to September in 2002. Overall, the maximum riverine N exports were 12.1% of total N inputs and 15.5% of the inorganic fertilizer N applied. Understanding N sources and exports in a village-scale catchment can provide a knowledge base for amelioration of diffuse agricultural pollution.

Agriculture↗