Biomedical subjects

Jingli Zhang

Publications and source records attributed to Jingli Zhang.

17 recordsLinked to original sources

PubMed2026

Natural variation in the PmbHLH162 promoter regulates anthocyanin biosynthesis and accumulation in Prunus mume.

Anthocyanin accumulation is a vital agronomic and ornamental trait, as it not only contributes to adaptation to environmental stress but also enhances ornamental value. In this study, a genome-wide association study (GWAS) was conducted using 328 accessions of mei (Prunus mume) to identify single-nucleotide polymorphisms (SNPs) associated with red pigmentation in petals, filaments, and xylem. Based on these significant SNPs, we defined 2 haplotypes (bHLH162hap1 and bHLH162hap2) and identified PmbHLH162, a bHLH transcription factor gene responsible for anthocyanin biosynthesis regulation. Transient silencing of PmbHLH162 in mei petals via Agrobacterium-mediated transformation resulted in significant color fading, whereas its overexpression dramatically elevated anthocyanin levels. Haplotype analysis showed that 2 promoter variants in bHLH162hap2 (Chr03_2669885 A/C and Chr03_2670272 A/G) alter the binding affinity of transcription factors PmWRKY18 and PmWRKY70. Stronger binding to the G/C alleles gave rise to higher PmbHLH162 expression in bHLH162hap2, thereby promoted red pigmentation in multiple tissues. By contrast, accessions carrying bHLH162hap1 displayed light/colorless phenotype without accumulation of red pigment. Furthermore, PmbHLH162 interacted respectively with PmMYC2, PmTT8, and PmEGL1 to form heterodimers, and markedly enhanced PmMYC2-mediated transcriptional activation of the anthocyanin biosynthetic structural genes PmCHS and PmANS. Geographic haplotype analysis revealed that bHLH162hap2 was predominantly enriched in high-latitude northern populations but was declining markedly at lower latitudes. Collectively, our study reveals the genetic and molecular basis underlying anthocyanin accumulation in mei and identifies a PmbHLH162-PmMYC2 regulatory module in which PmbHLH162 enhances PmMYC2-mediated activation of key anthocyanin biosynthetic genes. The additional interactions of PmbHLH162 with the MBW-associated bHLH factors PmTT8 and PmEGL1 further suggest potential crosstalk between this module and the canonical anthocyanin regulatory network.

Anthocyanins↗

PubMed2006

Methylated polyphenols are poor "chemical" antioxidants but can still effectively protect cells from hydrogen peroxide-induced cytotoxicity.

Several polyphenolic compounds, including flavonoids and phenolic acids, were compared with their per-methylated forms in both chemical and cell-based assays for antioxidant capacity. Methylation largely eliminated "chemical" antioxidant capacity, according to ferric reducing antioxidant power and oxygen radical absorbance capacity assays. Methylation, however, only moderately reduced protection of human Jurkat cells in culture, from hydrogen peroxide-mediated cytotoxicity, at physiologically relevant concentrations. Neither methylated nor un-methylated compounds were detectably metabolized by the cells. It appears that the protective mechanism of polyphenolic antioxidants against high concentrations of hydrogen peroxide in human cells may be largely unrelated to chemical antioxidant capacity.

Antioxidants↗

PubMed2006

Patch-clamp studies in the CNS illustrate a simple new method for obtaining viable neurons in rat brain slices: glycerol replacement of NaCl protects CNS neurons.

Viable neurons in brain slices are crucial for electrophysiological studies. The present study describes a new method for obtaining viable cells in several regions of the central nervous system including the ventral tegmental area, the hypothalamus, the periaqueductal grey matter and the spinal cord. The essence of the method was to use a modified artificial cerebrospinal fluid (ACSF) in which all NaCl was replaced initially by equi-osmotic glycerol. This modified glycerol-based ACSF was used during slice preparation. The underlying principle for the modification is to prevent the possible acute neurotoxic effects of passive chloride entry, subsequent cell swelling and lysis. This method significantly increased the live/dead ratio in morphology compared to the normal ACSF or sucrose-base ACSF, in which NaCl was replaced by sucrose. An examination of some electrophysiological and pharmacological properties of the neurons in these preparations, by means of current-clamp and voltage-clamp recordings, revealed similar properties of those neurons obtained with the traditional ACSF method. Due to the increase in the number of viable neurons, the new ACSF increases the productivity of experiments. Based on our data, we propose that this glycerol-based solution may protect CNS neurons.

Animals↗

PubMed2006

Detection and quantitation of serum mesothelin, a tumor marker for patients with mesothelioma and ovarian cancer.

PURPOSE: To determine whether mesothelin, a cell surface protein highly expressed in mesothelioma and ovarian cancer, is shed into serum and if so to accurately measure it. EXPERIMENTAL DESIGN: We developed a sandwich ELISA using antibodies reacting with two different epitopes on human mesothelin. To quantitate serum mesothelin levels, a standard curve was generated using a mesothelin-Fc fusion protein. Sera from 24 healthy volunteers, 95 random hospital patients, 56 patients with mesothelioma, and 21 patients with ovarian cancer were analyzed. Serum mesothelin levels were also measured before and after surgical cytoreduction in six patients with peritoneal mesothelioma. RESULTS: Elevated serum mesothelin levels were noted in 40 of 56 (71%) patients with mesothelioma and in 14 of 21 (67%) patients with ovarian cancer. Serum mesothelin levels were increased in 80% and 75% of the cases of mesothelioma and ovarian cancer, respectively, in which the tumors expressed mesothelin by immunohistochemistry. Out of the six patients with peritoneal mesothelioma who underwent surgery, four had elevated serum mesothelin levels before surgery. Out of these four patients, three had cytoreductive surgery and the serum mesothelin level decreased by 71% on postoperative day 1 and was undetectable by postoperative day 7. CONCLUSIONS: We developed a serum mesothelin assay that shows that mesothelin is elevated in patients with mesothelioma and ovarian cancer. The rapid decrease in mesothelin levels after surgery in patients with peritoneal mesothelioma suggests that serum mesothelin may be a useful test to monitor treatment response in mesothelin-expressing cancers.

Adult↗

PubMed2006

Lipid peroxidation inhibition capacity assay for antioxidants based on liposomal membranes.

An in vitro antioxidant assay has been developed to better reflect the in vivo conditions of antioxidants interacting with membrane and lipid surfaces. The lipid peroxidation inhibition capacity (LPIC) method measures the ability of both lipophilic and hydrophilic antioxidants to protect a lipophilic fluorescent probe 4, 4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid, incorporated in the membrane, from 2,2'-azobis(2-amidinopropane)hydrochloride generated radicals in the surrounding aqueous solution. Antioxidant activities of test compounds were measured either after they were mixed with preformed liposomes (LPIC(Mixed)) or after they were incorporated into liposomes (LPIC(Inco)) as they were made. The results were analysed to determine how the method of mixing and the structures of the antioxidants influenced their protection of the membrane from free radical attack. The LPIC(Mixed) values were larger than the LPIC(Inco) values for a range of 12 structurally diverse antioxidant compounds. However, there was no linear correlation between the lipophilicities, as measured by their partition coefficient, log P and either LPIC(Inco) or LPIC(Mixed) values. A strong correlation was found between LPIC(Inco) and LPIC(Mixed) values.

Antioxidants↗

PubMed2006

Free radical scavenging and cytoprotective activities of phenolic antioxidants.

The free radical scavenging activities of three flavonoids (quercetin, rutin and catechin) and four hydroxycinnamic acids (caffeic, ferulic, sinapic, and chlorogenic acids) were evaluated using both oxygen radical absorbance capacity (ORAC) and lipid peroxidation inhibition capacity (LPIC) assays. The cytoprotective effects of these compounds were also measured by the degree of protection against H(2)O(2)-induced damage of human Jurkat cells. All compounds exhibited protection against H(2)O(2)-mediated cytotoxicity in a dose-dependent manner. The concentrations required to result in a 50% reduction in cell death (EC(50) value) were calculated from their dose-response curves. These ranged from 0.15-2.65 microM. Overall, the four hydroxycinnamic acids tested were less effective than the three flavonoids, and of all compounds tested, quercetin offered the strongest protection against H(2)O(2)-induced cell death. A comparison of the results showed that the ability to inhibit peroxidation of lipids in a liposomal system (LPIC) correlated well with the cytoprotective activities (EC(50)), but not with the ability to protect an aqueous fluorescent substrate in the ORAC assays. The results suggest that the behavior of antioxidants in a liposomal membrane is to some extent similar to the mechanism involved in the protection of living cells from oxidative damage.

Antioxidants↗

PubMed2005

Humoral immune response to mesothelin in mesothelioma and ovarian cancer patients.

PURPOSE: Mesothelin is a glycosyl-phosphatidylinositol-anchored glycoprotein present on the cell surface. Mesothelin is a differentiation antigen that is highly expressed on mesothelioma, ovarian cancer, and pancreatic cancer. The existence of a spontaneous humoral immune response to mesothelin in humans has not been fully studied. Here we addressed the issue of whether mesothelin elicits a humoral immune response in patients with mesothelioma and ovarian cancer. EXPERIMENTAL DESIGN: Using an ELISA, we analyzed immunoglobulin G antibodies specific for mesothelin in sera from patients with mesothelioma and epithelial ovarian cancer. Tumor specimens were examined by immunohistochemistry for mesothelin protein expression. RESULTS: Elevated levels of mesothelin-specific antibodies were detected in the sera of 39.1% of patients with mesothelioma (27 of 69 patients) and 41.7% with epithelial ovarian cancer (10 of 24 patients) when compared with a normal control population (44 blood donors; P < 0.01 for both mesothelioma and ovarian cancer). We also found that 53% to 56% of patients with mesothelin immunostaining-positive mesothelioma and ovarian cancer had antibodies specific for mesothelin, whereas only 0% to 8% of patients with negative mesothelin immunostaining had detectable mesothelin-specific antibodies (chi(2) test: P < 0.01 for mesothelioma and P = 0.025 for ovarian cancer). CONCLUSIONS: Our findings indicate that mesothelin is a new tumor antigen in patients with mesothelioma and ovarian cancer and the immunogenicity of mesothelin is associated with its high expression on the tumor cells. Mesothelin represents an excellent target for immune-based therapies.

Adult↗

PubMed2005

Antibody humanization by framework shuffling.

We report here the humanization of a mouse monoclonal antibody (mAb B233) using a new technique which we call framework shuffling. mAb B233 was raised against the human receptor tyrosine kinase EphA2 which is selectively up-regulated in many cancer cell lines and as such constitutes an attractive target for cancer therapy. The six CDRs of B233 were fused in-frame to pools of corresponding individual human frameworks. These human frameworks encompassed all known heavy and light (kappa) chain human germline genes. The resulting Fab combinatorial libraries were then screened for binding to the antigen. A two-step selection process, in which the light and heavy chains of the parental mAb were successively humanized, resulted in the identification of several humanized variants that retained binding to EphA2. More precisely, after conversion to human IgG1, the dissociation constants of three select fully humanized variants ranged from 3 to 48 nM. This brings the best framework-shuffled, humanized binder within 5-fold of the avidity of parental mAb B233. Importantly, these humanized IgGs also possessed biochemical activities similar to those of parental mAb B233 as judged by induction of EphA2 phosphorylation. Thus, without requiring any rational design or structural information, this new humanization approach allows to rapidly identify various human framework combinations able to support the structural feature(s) of the CDRs which are essential for binding and functional activity.

Amino Acid Sequence↗

PubMed2004

Presynaptic glycine receptors on GABAergic terminals facilitate discharge of dopaminergic neurons in ventral tegmental area.

GABA-mediated postsynaptic currents (IPSCs) were recorded from dopaminergic (DA) neurons of the ventral tegmental area (VTA) of rats, in acute brain slices, and from enzymatically or mechanically dissociated neurons. In young rats (3-10 d of age), where GABA is excitatory, glycine (1-3 microm) and taurine (10-30 microm) increased the amplitude of evoked IPSCs (eIPSCs) and the frequency of spontaneous IPSCs (sIPSCs) but had minimal postsynaptic effects. Strychnine (1 microm) blocked the action of glycine; when applied alone, it reduced the amplitude of eIPSCs and the frequency of sIPSCs, indicating a tonic facilitation of GABAergic excitation by some endogenous glycine agonist(s). In medium containing no Ca2+, or with Cd2+ or tetrodotoxin added, the amplitude and especially the frequency of sIPSCs greatly diminished. In many cells, glycine had no effect on remaining miniature IPSCs, suggesting a preterminal site of glycine receptors (GlyRs). Fura-2 fluorescent imaging showed a glycine-induced increase of [Ca2+] in nerve terminals (on DA neurons), which was suppressed by strychnine or 3 microm omega-conotoxin MVIIA. Therefore, the presynaptic GlyR-mediated facilitation of GABAergic transmission seems to be mediated by N- and/or P/Q-type Ca2+ channels. In older rats (22-30 d of age), where GABA causes inhibition, the effect of strychnine on GABAergic IPSCs was reversed to facilitation, indicating a tonic glycinergic inhibition of GABA release. Furthermore, glycine (1-3 microm) reduced the amplitude of eIPSCs and the frequency of sIPSCs. Hence, the overall effect of the presynaptic action of glycine is to enhance the firing of DA cells, both in very young and older rats.

Age Factors↗

PubMed2004

A synthetic Rev-independent bovine immunodeficiency virus-based packaging construct.

Replication competent lentivirus (RCL) has been the major safety concern associated with applications of lentivirus-based gene transfer systems for human gene therapy. Minimization and elimination of overlaps between the packaging and the transfer vector constructs are expected to reduce the potential to generate RCL. We previously developed second- and third-generation bovine immunodeficiency virus (BIV)-based gene transfer systems. However, some sequence homologies between the vector and gag/pol packaging constructs remained. In order to minimize the sequence homologies, we recoded gag/pol with codon usage optimized for expression in human cells in this report. Expression of the recoded gag/pol was Rev/RRE independent. Thus, RRE was eliminated from the packaging construct, thereby removing a 312 bp block of homology. In addition, recoding gag/pol minimized overall homologies between the packaging and transfer vector constructs. Vectors generated by the recoded packaging construct with a four plasmid system had titers greater than 1 x 10(6) transducing units per milliliter, equivalent to those of the earlier generation systems. The vectors were functional in vitro and efficiently transduced rat pigment epithelial cells in vivo. Generation of the synthetic packaging construct provides further advances to the safety of lentiviral vectors for clinical applications.

Animals↗

PubMed2004

Activation of extracellular signal-activated kinase by angiotensin II-induced Gq-independent epidermal growth factor receptor transactivation.

Multiple signaling pathways link the angiotensin II (Ang II) type 1 (AT1) receptor to Gq-dependent inositol phosphate (IP) production and Gq-independent phospho-extracellular signal-activated kinase (p-ERK) 1/2 activation by Ang II in the regulation of cardiovascular vasoconstriction and cell growth, respectively. An Ang II analogue, [Sar1, Ile4, Ile8]Ang II, did not stimulate Gq-dependent IP production, but still activated Gq-independent p-ERK1/2 in human coronary artery smooth muscle cells as well as in a cell line that stably expressed AT1. This activation was mostly mediated by [Sar1, Ile4, Ile8]Ang II-induced Gq-independent epidermal growth factor receptor transactivation. We found that AT1 receptor signaling shows bifurcation into functionally separate pathways. A clear understanding of this unique signaling may be necessary for the development of therapeutic agents to treat disorders such as hypertension and cardiac hypertrophy.

Angiotensin II↗

PubMed2003

[Comparative study on image analysis and manual counting of immunohistochemistry].

With the use of computer image analysis (IA) and manual counting, the immunohistochemistry (IHC) results on PS2, ER and c-erB-2 of breast cancer which represent positive expression of cytoplasm, cell nucleus and cytomembrane are analyzed and compared. Then the advantages, disadvantages and repetition of the two methods are discussed and the correlation between image analysis and manual counting is estimated. The results of this study indicate that IA has better repetition in estimation of positive expression of cytoplasm, cell nucleus and cytomembrane, whereas manual counting has better repetition only in the positive expression of cell nucleus and cytomembrane, and the two methods have positive correlation in estimation of IHC results. In addition, some problems in image processing are discussed in this paper.

Breast Neoplasms↗

PubMed2003

[Clonal growth of stoloniferous herb Potentilla anserina on degraded and non-degraded alpine meadow soil].

The clonal growth of Potentilla anserina on degraded and non-degraded Kobresia humilis meadow soil was studied by a transplanting experiment in the field. No significant differences in numbers of stolons, height, and leave size per mother ramet were observed between the two soils, but the numbers of leaves per mother ramet, length and width of stolon, and spacer length were significantly different. There were more leaves per mother ramet, longer stolon and spacer, and wider stolon on degraded soil, where available nutrient was poor than in non-degraded soil. Under degraded alpine meadow soil condition, the clonal plant species might produce much more photosynthetic product to support stolon growth by the increase of leave numbers per mother ramet, and the longer and wider stolon could intensify the foraging ability of the mother ramet that would benefit to daughter ramet. Both mother and daughter ramet of Potentilla anserina invested much more biomass to their underground part (root system) in non-degraded soil to increase the survival rate of daughter ramet.

Biomass↗

PubMed2002

Mapping of the bovine immunodeficiency virus packaging signal and RRE and incorporation into a minimal gene transfer vector.

Gene transfer systems based on lentiviruses have emerged as promising gene delivery vehicles for human gene therapy due to their ability to efficiently transduce nondividing target cells. Both primate and nonprimate lentiviruses have been used for construction of lentiviral vectors. An early generation of gene transfer system based on bovine immunodeficiency virus (BIV) has been developed (R. D. Berkowitz, H. Ilves, W. Y. Lin, K. Eckert, A. Coward, S. Tamaki, G. Veres, and I. Plavec, 2001, J. Virol. 75, 3371-3382). In this study, we mapped the BIV Rev response element (RRE) to 312 bp of the Env coding region. Furthermore, we compared transduction efficiencies of vectors containing different portions of the BIV Gag coding region and found that the first 104 bp of gag contains a functional part of the BIV packaging signal. These findings enabled the generation of a minimal BIV-based lentiviral vector. The minimal transfer vector construct consists of a self-inactivating long terminal repeats (LTR), minimal packaging sequence, putative central polypurine tract, minimal RRE, an internal promoter driving the gene of interest, and a woodchuck hepatitis posttranscriptional regulatory element. In addition, we constructed a BIV packaging construct containing gag/pol, minimal Rev/RRE, and the accessory gene vpy. The regulatory gene tat and the accessory genes vif and vpw have been inactivated or truncated. The current system has significantly reduced regions of homologies between the transfer vector and the packaging constructs. The vectors generated from this system achieved a titer of greater than 1 x 10(6) transducing units per milliliter and are fully functional as indicated by their ability to efficiently transduce both dividing and nondividing cells. These modifications should provide improved safety features for the BIV-based gene transfer system.

Base Sequence↗

PubMed2002

TM2-TM7 interaction in coupling movement of transmembrane helices to activation of the angiotensin II type-1 receptor.

Agonist-induced rigid body motion of transmembrane (TM) helices has been established as a unifying mechanism in the activation of the G protein-coupled receptors. In attempts to measure specific conformational transitions during the activation of the type 1 receptor for angiotensin II (AT(1)), we found a decrease in accessibility of Cys(76) in the second TM helix, suggesting that the orientation of TM2 is altered (Miura, S., and Karnik, S. S. (2002) J. Biol. Chem. 277, 24299-24305). Now we provide evidence that the TM2 helical movement plays a role in regulating the activated state of the AT(1) receptor, and this role may involve an interaction between TM2 and TM7. Alanine substitution of native Cys(296) in TM7 leads to increased accessibility of Cys(289) and diminished response to bound agonist. Both effects of the C296A mutation are suppressed when combined with F77A and N111G mutants. The TM7 conformation and the sensitivity of Cys(289) altered by C296A mutation are suppressed by the F77A mutation in TM2 to salvage function. We show that the F77A mutant alters orientation of both TM2 and TM7 but does not induce constitutive activity in suppressing the C296A mutant effects. Thus, interaction of TM2 and TM7 is important for transmembrane signal transduction in the AT(1) receptor.

Amino Acid Sequence↗

PubMed2002

Characterization of rhodamine conjugated Agiotensin II peptide: synthesis, analysis and receptor binding and internalization.

The results in this study show that the rhodamine fluorophore can be specifically conjugated to Angiotensin II at Lys3 residue (substituted for a Val) without altering the biological activity of the parent compound. The conjugated peptide was characterized using HPLC, mass spectrometry, and N-terminal sequencing. The rhodamine-Angiotensin II binds effectively to AT1 receptor and gets internalized in clathrin coated vesicles by endocytosis. These results clearly suggest the usefulness of fluorophore-conjugated peptides in studies such as, ligand-receptor binding, and ligand-receptor complex internalization, for drug delivery using cell receptors and as an alternative to peptide hormone radioimmunoassays.

Angiotensin II↗

PubMed2002

[Study on intervention and comparison of rational use of antibiotics on perioperative period of clean incision and clean-defiled incision].

OBJECTIVE: To explore a set of scientific evaluation and intervention methods on perioperatur period which fits for China's situation, and to promote the development of rational drug use. METHODS: Two would tertiary general hospitals were selected and separated in to intervention group and control group. Intervention was carried out and compared at the same period on inpatient surgical cases of thryroidectomy, mastectomy, cholescystectomy, and hysteromyomectomy plus appendix. RESULTS: The average drug costs was decreased from 1 601.27 yuan to 1 489.59 yuan and the average antibiotics use from 740.20 yuan to 352.03 yuan (P < 0.01) in the intervention group pre and post intervention. There was a remarkable improvement on the rationality of antibiotics use in intervention group, from 31.35% to 91.81% (P < 0.01) pre and post intervention, implemented in the hospital. CONCLUSION: It is practicable and effective to implement rational drug use where intervention was carried out, since it plays an active role on promoting safely, effectively and economic antibiotic use in China.

Anti-Bacterial Agents↗