PubMed Health⌕ Search

Biomedical subjects

Chang Liu

Publications and source records attributed to Chang Liu.

At least 37 records · Page 2Linked to original sources
PubMed2025

Simultaneous Visualization of Protein and Genomic Regions in Plant Nuclei.

Immunohistostaining (IHS) is a widely used technique in diagnostic and research laboratories in which specific antibodies are used to detect and visualize a protein of interest in cells or tissues. Similarly, with specific oligonucleotide probes, the fluorescence in situ hybridization (FISH) method allows one to visualize genomic regions and to analyze its localization in the nuclear space. Here, we describe a combined FISH-IHS technique that enables researchers to determine the localization of protein and genomic loci in plant nuclei simultaneously. This method can be applied to extracted nuclei and sections of paraffin-embedded tissues. It provides a valuable tool to improve our understanding of nuclear dynamics by revealing the spatial relationship between specific genomic loci and target proteins.

In Situ Hybridization, Fluorescence↗
PubMed2024

The AKR1C1-CYP1B1-cAMP signaling axis controls tumorigenicity and ferroptosis susceptibility of extrahepatic cholangiocarcinoma.

Extrahepatic cholangiocarcinoma (ECC), a highly malignant type of cancer with increasing incidence, has a poor prognosis due to limited treatment options. Based on genomic analysis of ECC patient samples, here we report that aldo-keto reductase family 1 member C1 (AKR1C1) is highly expressed in human ECC tissues and closely associated with ECC progression and poor prognosis. Intriguingly, we show that inducible AKR1C1 knockdown triggers ECC cells to undergo ferroptosis. Mechanistically, AKR1C1 degrades the protein stability of the cytochrome P450 family member CYP1B1, a newly discovered mediator of ferroptosis, via ubiquitin-proteasomal degradation. Additionally, AKR1C1 decreases CYP1B1 mRNA level through the transcriptional factor aryl-hydrocarbon receptor (AHR). Furthermore, the AKR1C1-CYP1B1 axis modulates ferroptosis in ECC cells via the cAMP-PKA signaling pathway. Finally, in a xenograft mouse model of ECC, AKR1C1 depletion sensitizes cancer cells to ferroptosis and synergizes with ferroptosis inducers to suppress tumor growth. Therefore, the AKR1C1-CYP1B1-cAMP signaling axis is a promising therapeutic target for ECC treatment, especially in combination with ferroptosis inducers.

Humans↗
PubMed2006

Attachment of motile bacterial cells to prealigned holed microarrays.

Construction of biomotors is an exciting area of scientific research that holds great promise for the development of new technologies with broad potential applications in areas such as the energy industry and medicine. Herein, we demonstrate the fabrication of prealigned microarrays of motile Escherichia coli bacterial cells on SiOx substrates. To prepare these arrays, holed surfaces with a gold layer on the bottom of the holes were utilized. The attachment of bacteria to the holes was achieved via nonspecific interactions using poly-l-lysine hydrobromide (PLL). Our data suggest that a single motile bacterial cell can be selectively attached to an individual hole on a surface and bacterial cell binding can be controlled by altering the pH, with the greatest occupancy occurring at pH 7.8. Cells attached to hole arrays remained motile for at least 4 h. These data indicate that holed surface structures provide a promising footprint for the attachment of motile bacterial cells to form high-density site-specific functional bacterial microarrays.

Cells, Immobilized↗
PubMed2006

Distant touch hydrodynamic imaging with an artificial lateral line.

Nearly all underwater vehicles and surface ships today use sonar and vision for imaging and navigation. However, sonar and vision systems face various limitations, e.g., sonar blind zones, dark or murky environments, etc. Evolved over millions of years, fish use the lateral line, a distributed linear array of flow sensing organs, for underwater hydrodynamic imaging and information extraction. We demonstrate here a proof-of-concept artificial lateral line system. It enables a distant touch hydrodynamic imaging capability to critically augment sonar and vision systems. We show that the artificial lateral line can successfully perform dipole source localization and hydrodynamic wake detection. The development of the artificial lateral line is aimed at fundamentally enhancing human ability to detect, navigate, and survive in the underwater environment.

Animals↗
PubMed2006

Controlling the morphology of Ag nanoclusters by ion implantation to different doses and subsequent annealing.

Ag ions were implanted at 200 keV into silica with nominal doses ranging from 5x10(16) to 2x10(17) ions/cm2. We find that nanovoid-containing Ag nanoclusters form in the implanted samples with doses higher than 1x10(17) ions/cm2. When the dose is increased to 2x10(17) ions/cm2, the nanovoids gradually shrink and form a sandwiched nanocluster-nanovoid-nanocluster structure. The evolution of sandwiched nanoclusters during annealing was observed by in situ transmission electron microscopy experiments. Potential mechanisms for the formation and evolution of the irradiation-induced nanovoids and the sandwiched structure nanoclusters with increasing doses are discussed. The structural optimization of the sandwiched structure nanoclusters was performed by molecular mechanics calculations.

Journal Article↗
PubMed2006

A bio-barcode assay for on-chip attomolar-sensitivity protein detection.

Functionalized nanoparticles hold great promise in realizing highly sensitive and selective biodetection. We report a single disposable chip which is capable of carrying out a multi-step process that employs nanoparticles--a bio-barcode assay (BCA) for single protein marker detection. To illustrate the capability of the system, we tested for the presence of prostate specific antigen (PSA) in buffer solution and goat serum. Detection was accomplished at PSA concentrations as low as 500 aM. This corresponds to only 300 copies of protein analytes using 1 microL total sample volume. We established that the on-chip BCA for PSA detection offers four orders of magnitude higher sensitivity compared to commercially available ELISA-based PSA tests.

Animals↗
PubMed2006

Self-associating block copolymer networks for microchip electrophoresis provide enhanced DNA separation via "inchworm" chain dynamics.

We describe a novel class of DNA separation media for microchip electrophoresis, "physically cross-linked" block copolymer networks, which provide rapid (<4.5 min) and remarkably enhanced resolution of DNA in a size range critical for genotyping. Linear poly(acrylamide-co-dihexylacrylamide) (LPA-co-DHA) comprising as little as 0.13 mol % dihexylacrylamide yields substantially improved electrophoretic DNA separations compared to matched molar mass linear polyacrylamide. Single-molecule videomicroscopic images of DNA electrophoresis reveal novel chain dynamics in LPA-co-DHA matrixes, resembling inchworm movement, to which we attribute the increased DNA resolution. Substantial improvements in DNA peak separation are obtained, in particular, in LPA-co-DHA solutions at polymer/copolymer concentrations near the interchain entanglement threshold. Higher polymer concentrations yield enhanced separations only for small DNA molecules (<120 base pairs). Hydrophobically cross-linked networks offer advantages over conventional linear polymers based on enhanced separation performance (or speed) and over chemically cross-linked gels because hydrophobic cross-links can be reversibly broken, allowing facile microchannel loading.

DNA↗
PubMed2006

GLABROUS INFLORESCENCE STEMS modulates the regulation by gibberellins of epidermal differentiation and shoot maturation in Arabidopsis.

As a plant shoot matures, it transitions through a series of growth phases in which successive aerial organs undergo distinct developmental changes. This process of phase change is known to be influenced by gibberellins (GAs). We report the identification of a putative transcription factor, GLABROUS INFLORESCENCE STEMS (GIS), which regulates aspects of shoot maturation in Arabidopsis thaliana. GIS loss-of-function mutations affect the epidermal differentiation of inflorescence organs, causing a premature decrease in trichome production on successive leaves, stem internodes, and branches. Overexpression has the opposite effect on trichome initiation and causes other heterochronic phenotypes, affecting flowering and juvenile-adult leaf transition and inducing the formation of rosette leaves on inflorescence stems. Genetic and gene expression analyses suggest that GIS acts in a GA-responsive pathway upstream of the trichome initiation regulator GLABROUS1 (GL1) and downstream of the GA signaling repressor SPINDLY (SPY). GIS mediates the induction of GL1 expression by GA in inflorescence organs and is antagonized in its action by the DELLA repressor GAI. The implication of GIS in the broader regulation of phase change is further suggested by the delay in flowering caused by GIS loss of function in the spy background. The discovery of GIS reveals a novel mechanism in the control of shoot maturation, through which GAs regulate cellular differentiation in plants.

Amino Acid Sequence↗
PubMed2006

Different attitudes of oncology clinicians toward truth telling of different stages of cancer.

OBJECTIVES: To investigate different attitudes of oncology clinicians toward whether and how to disclose diagnosis to patients with different stages of cancer. MATERIALS AND METHODS: A questionnaire investigating physician's demographic information and attitude toward truth telling was delivered to 256 Chinese oncology clinicians. RESULTS: Two hundred thirty-two (90.6%) physicians completed the questionnaire. Of these oncology clinicians, 87.5% reported that a patient with early-stage cancer should be informed of the diagnosis, while only 40.5% believed that a patient with terminal illness should know the truth (P<0.001). Physicians who preferred to tell the truth reported that patients with early or terminal stage of cancer should be informed by the doctor-in-charge (81.3 vs 77.7%, respectively; P>0.05), immediately after the diagnosis (83.7 vs 87.2%, respectively), and in a quiet and undisturbed room (63.5 vs 68.1%, respectively; P>0.05). In stepwise multiple logistic regression analyses, no demographic information showed association with truth telling of early-stage cancer. Women doctors [odds ratio (OR), 2.25; 95% CI, 1.31 to 3.89; P=0.004] were more likely than men to want the patient to be informed of the terminal illness. Physicians with cancer relatives (OR, 0.55; 95% CI, 0.31 to 0.97; P=0.04) were less likely than physicians without cancer relatives to want the patient to be informed of the terminal illness. CONCLUSION: Oncology clinicians differed in their attitudes toward truth telling of different stages of cancer. Physicians reported that the doctor-in-charge should be the ones to disclose the condition of the patient, immediately after the diagnosis, and in a quiet and undisturbed room.

Adult↗
PubMed2006

The Png1-Rad23 complex regulates glycoprotein turnover.

Misfolded proteins in the endoplasmic reticulum (ER) are destroyed by a pathway termed ER-associated protein degradation (ERAD). Glycans are often removed from glycosylated ERAD substrates in the cytosol before substrate degradation, which maintains the efficiency of the proteasome. Png1, a deglycosylating enzyme, has long been suspected, but not proven, to be crucial in this process. We demonstrate that the efficient degradation of glycosylated ricin A chain requires the Png1-Rad23 complex, suggesting that this complex couples protein deglycosylation and degradation. Rad23 is a ubiquitin (Ub) binding protein involved in the transfer of ubiquitylated substrates to the proteasome. How Rad23 achieves its substrate specificity is unknown. We show that Rad23 binds various regulators of proteolysis to facilitate the degradation of distinct substrates. We propose that the substrate specificity of Rad23 and other Ub binding proteins is determined by their interactions with various cofactors involved in specific degradation pathways.

Amino Acid Sequence↗
PubMed2006

Molecular characterization of a HMW glutenin subunit allele providing evidence for silencing of x-type gene on Glu-B1.

Understanding the molecular structure of high-molecular-weight glutenin subunit (HMW-GS) may provide useful evidence for the study on the improvement of quality of cultivated wheat and the evolution of Glu-1 alleles. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) shows that the subunits encoded by Glu-B1 were null, named 1Bxm, in a Triticum turgidum var. dicoccoides line PI94640. Primers based on the conserved regions in wheat HMW-GS gene promoter and coding sequences were used to amplify the genomic DNA of line PI94640. The PCR products were sequenced, and the total nucleotide sequence of 3,442 bp including upstream sequence of 1,070 bp was obtained. Compared with the reported gene sequences of Glu-1Bx alleles, the promoter region of the Glu-1Bxm showed close resemblance to 1Bx7. The Glu-1Bxm coding region differs from the other Glu-1Bx alleles for a deduced mature protein with only 212 residues, and a stop codon (TAA) at 637 bp downstream from the start codon was present, which was probably responsible for the silencing of x-type subunit genes at the Glu-B1 locus. Phylogenetic tree based on the nucleotide sequence alignment of HMW glutenin subunit genes showed that 1Bxm was the most ancient type of Glu-B1 alleles, suggesting that the evolution rates are different among Glu-1Bx genes. Further study on the contribution of the unique silenced Glu-B1 alleles to quality improvement was also discussed.

Alleles↗
PubMed2006

The effects of urotensin-II on proliferation of pheochromocytoma cells and mRNA expression of urotensin-II and its receptor in pheochromocytoma tissues.

This study was conducted to investigate the effects of urotensin-II (UII) on the proliferation of pheochromocytoma cells and the mRNA expression of UII and its receptor G protein-coupled receptor 14 (GPR14) in normal adrenal and human pheochromocytoma tissues. The effects on the cell proliferation by different UII concentrations and at different time were observed with the MTT method in both rat pheochromocytoma cell line (PC12 cell) and human pheochromocytoma cells. The mRNA expression of UII and GPR14 was evaluated by RT-PCR. UII had no significant effect on the proliferation in PC12 cells, but promoted the proliferation of human pheochromocytoma cells. The mRNA expression of UII and GPR14 in pheochromocytoma was lower than that in normal adrenal tissues. But mRNA expression of UII and GPR14 in adrenal pheochromocytomas was lower than that in extra-adrenal pheochromocytomas. Thus, UII and its receptor GPR14 exert a possible effect in the pathogenesis of pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed2006

[Sequence variation of chloroplast gene infA-rpl36 region occurred in some Triticeae species].

Based on the sequenced wheat chloroplast genome (cpDNA), a pair of primers in infA-rp136 region was designed and used to amplify DNA from 12 diploid or polyploid Triticeae species. The 12 PCR products were cloned and sequenced. The resulting sequences ranged from 584 to 601 bp. DNA sequence analysis revealed that variation was higher in their intergenic regions than in their coding regions. Among these 12 species, the DNA sequence of coding region of infA gene showed homology as high as 97 percent, indicating that the infA gene is highly conserved among species. However, substantial deletions and insertions were found in 5 out of 12 deduced amino acid sequences, confirming that infA is one of the most evolutionally active cpDNA genes. Whereas the low variation was observed in rp136 gene, implying that the different genes has different evolutionary speed. The constructed phylogenetic trees demonstrate that the polyploidy species Thinopyrum intermedium might have different origin of cytoplasm, and their cytoplasm origins are as complex as their nuclear genome origins.

Amino Acid Sequence↗
PubMed2006

[Immunization with dendritic cells infected with human AFP adenovirus vector effectively elicits immunity against mouse hepatocellular carcinomas].

OBJECTIVE: To investigate the effects of dendritic cells (DCs) infected with adenovirus vector encoding xenogeneic alpha-fetoprotein (AFP) on breaking the immune tolerance and induction of immunity against hepatocellular carcinomas. METHODS: Human and mouse alpha-fetoprotein full-length cDNA were cloned from human HepG2 and mouse Hepa 1 - 6 hepatoma cell lines, respectively, using RT-PCR, and then inserted into adenoviral shuttle vectors to construct Ad hAFP and Ad mAFP. Mice were immunized with Ad hAFP-infected DC and in vitro CTL activity against Hepa 1 - 6 cells was examined by standard (51)Cr release assay. Survival was studied of the immunized mice, with or without depletion of CD8+ or CD4+ T cells, inoculated with Hepa 1 - 6 mouse hepatoma cells. RESULTS: The lytic activity of CTL elicited by the Ad hAFP-infected DCs were much stronger than that by Ad mAFP-infected DCs. 80% of the Ad hAFP/DCs-immunized mice of the inoculated with 5 x 10(6) Hepa 1 - 6 hepatoma cells were still alive two months after inoculation. However, the Ad mAFP/DCs-immunized mice inoculated with 1 x 10(6) Hepa 1 - 6 cells were just 20% surviving two months later. Depletion of CD8+ or CD4+ T cells abolished such an antigen-specific immunity elicited by the DCs infected with Ad hAFP. CONCLUSION: Adenovirus vector-mediated xenogeneic AFP-infected DCs can effectively break the immune tolerance to hepatocellular carcinomas in an animal model and induce strong antigen-specific T cell response, which are dependent on CD8+ and CD4+ T cells.

Adenoviridae↗
PubMed2006

Leishmania amazonensis infections in Oryzomys acritus and Oryzomys nitidus from Bolivia.

Three of thirteen Oryzomys acritus, Emmons and Patton 2005 (Rodentia: Muridae: Sigmodontinae) and 3 of 17 Oryzomys nitidus, Thomas 1884, collected from Noël Kempff National Park, Bolivia, from 2002 to 2005, tested positive for Leishmania (Leishmania) amazonensis or L. (L.) mexicana and negative for Leishmania (Viannia) spp. using the polymerase chain reaction (PCR). Based on previous records of L. (L.) amazonensis in humans, rodents, and sand flies from Bolivia, and the geographic distributions of L. (L.) amazonensis and L. (L.) mexicana, it was concluded that the Oryzomys were infected with L. (L.) amazonensis. These results identify two additional species of Oryzomys as hosts of L. (L.) amazonensis, and identify an ecological region of Bolivia where L. (L.) amazonensis is enzootic.

Animals↗
PubMed2005

New insight into the solid electrolyte interphase with use of a focused ion beam.

The formation and evolution of the solid electrolyte interphase (SEI) film on the surface of natural graphite spheres in the electrolyte of 1 M LiPF6 in ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio 1:1) were investigated with use of focused ion beam (FIB) technology. Secondary electron FIB images clearly show the surface and cross-section morphology of the SEI film. The composition variation along the surface and cross section of the SEI film was also explored by the elemental line scan analysis (ELSA). The initial SEI film with an apparent thickness range of approximately 450 to approximately 980 nm is rough in morphology and nonuniform in composition, and contains small splits. After certain electrochemical cycles, the thickened SEI film displays microscale holes and obvious cracks on the surface, and the content of organic compounds increases. In addition, the concept of "internal SEI film" is first proposed based on the characterization of the cross section of the natural graphite spheres with the aid of FIB. Finally, the capacity fading mechanisms of the natural graphite spheres corresponding to different electrochemical stages are discussed.

Journal Article↗
PubMed2005

Effects of SWNT and metallic catalyst on hydrogen absorption/desorption performance of MgH2.

The microstructure and absorption/desorption characteristics of composite MgH2 and 5 wt % as-prepared single-walled carbon nanotubes (MgH2-5ap) obtained by the mechanical grinding method were investigated. Experimental results show that the MgH2-5ap sample exhibits faster absorption kinetics and relatively lower desorption temperature than pure MgH2 or MgH2-purified single-walled carbon nanotube composite. Storage capacities of 6.0 and 4.2 wt % hydrogen for the MgH2-5ap composite were achieved in 60 min at 423 and 373 K, respectively. Furthermore, its desorption temperature was reduced by 70 K due to the introduction of as-prepared single-walled carbon nanotubes (SWNTs). In addition, the different effects of SWNTs and metallic catalysts contained in the as-prepared SWNTs were also investigated and a hydrogenation mechanism was proposed. It is suggested that metallic particles may be mainly responsible for the improvement of the hydrogen absorption kinetics, and SWNTs for the enhancement of hydrogen absorption capacity of MgH2.

Journal Article↗