Biomedical subjects

Xia Chu

Publications and source records attributed to Xia Chu.

6 recordsLinked to original sources

PubMed2026

Lipid synthesis seems to drive proliferation in Men1 mouse adrenals and human adrenocortical cell lines.

Adrenocortical carcinoma (ACC) is a devastating disease with few effective treatments. The underlying molecular pathways remain largely unknown. To identify potential pathways and drivers relevant to ACC pathogenesis, we utilized histologically normal adrenals from heterozygous multiple endocrine neoplasia type 1 (Men1) mice to study early adrenocortical tumorigenesis. Employing mass spectrometry-based proteomic profiling, we identified 681 proteins, of which 52 displayed significant differential regulation in the adrenal tissues of heterozygous Men1 mice in comparison with their wild-type counterparts. Among these were fatty acid synthase (FASN) and ATP-citrate lyase (ACLY), two enzymes previously shown to be upregulated in several other types of tumors. To assess the functional impact of ACLY and FASN in ACC, we used H295R cells as the primary model. Cells were treated with SB-204990 (ACLY inhibitor) or C75 (FASN inhibitor), which both showed a dose-dependent antiproliferative effect. Lipidomic analysis revealed a significant reduction in palmitic acid and palmitoleic acid in treated cells compared to controls, supporting a mechanistic link between ACLY/FASN activity and lipid biosynthesis. Finally, data from The Cancer Genome Atlas showed significantly diminished survival outcomes among ACC patients exhibiting high ACLY or FASN expression. These findings underscore the potential importance of exploring the inhibition of lipid synthesis as a promising avenue for further research in the context of human ACC.

Animals↗

PubMed2005

A colorimetric method for point mutation detection using high-fidelity DNA ligase.

The present study reported proof-of-principle for a genotyping assay approach that can detect single nucleotide polymorphisms (SNPs) through the gold nanoparticle assembly and the ligase reaction. By incorporating the high-fidelity DNA ligase (Tth DNA ligase) into the allele-specific ligation-based gold nanoparticle assembly, this assay provided a convenient yet powerful colorimetric detection that enabled a straightforward single-base discrimination without the need of precise temperature control. Additionally, the ligase reaction can be performed at a relatively high temperature, which offers the benefit for mitigating the non-specific assembly of gold nanoparticles induced by interfering DNA strands. The assay could be implemented via three steps: a hybridization reaction that allowed two gold nanoparticle-tagged probes to hybrid with the target DNA strand, a ligase reaction that generates the ligation between perfectly matched probes while no ligation occurred between mismatched ones and a thermal treatment at a relatively high temperature that discriminate the ligation of probes. When the reaction mixture was heated to denature the formed duplex, the purple color of the perfect-match solution would not revert to red, while the mismatch gave a red color as the assembled gold nanoparticles disparted. The present approach has been demonstrated with the identification of a single-base mutation in codon 12 of a K-ras oncogene that is of significant value for colorectal cancers diagnosis, and the wild-type and mutant type were successfully scored. To our knowledge, this was the first report concerning SNP detection based on the ligase reaction and the gold nanoparticle assembly. Owing to its ease of operation and high specificity, it was expected that the proposed procedure might hold great promise in practical clinical diagnosis of gene-mutant diseases.

Cell Line↗

PubMed2005

Silver-enhanced colloidal gold metalloimmunoassay for Schistosoma japonicum antibody detection.

A silver-enhanced colloidal gold metalloimmunoassay has been proposed for the determination of Schistosoma japonicum antibody (SjAb) in rabbit serum. The adult worm antigen of S. japonicum (SjAg) was adsorbed passively on the walls of a polystyrene microwell and then reacted with the desired SjAb. The colloidal gold-labeled goat anti-rabbit IgG secondary antibody was adsorbed on the walls of the polystyrene microwells through the reaction with SjAb, followed by the silver enhancement process, dissolution of silver metal atoms in an acidic solution, and determination of dissolved silver ions by anodic stripping voltammetry (ASV) at a glassy-carbon electrode. Assay conditions were optimized, including the reaction time of SjAg with SjAb, the interaction of SjAb with the colloidal gold-labeled secondary antibody, the dilution ratio of the colloidal gold-labeled secondary antibody and the silver enhancement time. The integration of the anodic stripping peak current depended linearly on the SjAb logarithmic concentration over the range of 6.4 ng/ml to 100 microg/ml. A detection limit as low as 3.0 ng/ml SjAb was achieved, which was better than the piezoelectric body acoustic wave sensor (detection limit of 7.2 microg/ml) and the renewable amperometric immunosensor (detection limit of 0.36 microg/ml). Rabbit serum samples with various degrees of infection were analyzed, and the results demonstrate that the proposed method meets the requirements of clinical analysis.

Animals↗

PubMed2005

An electrochemical stripping metalloimmunoassay based on silver-enhanced gold nanoparticle label.

A novel, sensitive electrochemical immunoassay has been developed based on the precipitation of silver on colloidal gold labels which, after silver metal dissolution in an acidic solution, was indirectly determined by anodic stripping voltammetry (ASV) at a glassy-carbon electrode. The method was evaluated for a noncompetitive heterogeneous immunoassay of an immunoglobulin G (IgG) as a model. The influence of relevant experimental variables, including the reaction time of antigen with antibody, the dilution ratio of the colloidal gold-labeled antibody and the parameters of the anodic stripping operation, upon the peak current was examined and optimized. The anodic stripping peak current depended linearly on the IgG concentration over the range of 1.66 ng ml(-1) to 27.25 microg ml(-1) in a logarithmic plot. A detection limit as low as 1 ng ml(-1) (i.e., 6 x 10(-12) M) human IgG was achieved, which is competitive with colorimetric enzyme linked immuno-sorbent assay (ELISA) or with immunoassays based on fluorescent europium chelate labels. The high performance of the method is attributed to the sensitive ASV determination of silver (I) at a glassy-carbon electrode (detection limit of 5 x 10(-9) M) and to the catalytic precipitation of a large number of silver on the colloidal gold-labeled antibody.

Biosensing Techniques↗

PubMed2003

Competitive interactions of adriamycin and ethidium bromide with DNA as studied by full rank parallel factor analysis of fluorescence three-way array data.

The competitive interactions of adriamycin (AMC) and a fluorescence probe of ethidium bromide (EB) with DNA have been studied by full rank parallel factor analysis (FRA-PARAFAC) of fluorescence excitation-emission three-way data array. The excitation and emission spectra as well as the equilibrium concentrations of co-existing species in different reaction mixtures can be directly obtained by the FRA-PARAFAC treatment. The concordance of the resolved excitation and emission spectra of AMC, EB and EB-DNA with the standard spectra of these species confirmed the reliability of the equilibrium concentrations of these components in the reaction mixtures studied. The results obtained are valuable for providing a deeper insight into the competitive interaction mechanism of AMC and EB with DNA. The conclusion was directly given out that the interaction of AMC with DNA is the intercalating model. The FRA-PARAFAC method as exemplified by the present study provides an useful approach for studying the interaction of clinical drugs with DNA in the presence of disturbance of drug assistants.

Algorithms↗

PubMed2002

Competitive interaction of the antitumor drug daunorubicin and the fluorescence probe ethidium bromide with DNA as studied by resolving trilinear fluorescence data: the use of PARAFAC and its modification.

The competitive interaction with DNA of daunorubicin (DR), being present in the clinical anti-tumor drug daunoblastina, and the fluorescence probe ethidium bromide (EB) has been studied by parallel-factor analysis (PARAFAC) and full-rank parallel-factor analysis (FRA-PARAFAC) of a fluorescence excitation-emission three-way data array. The PARAFAC algorithm can furnish stable resolution results for the data array studied, if the estimated number of chemical components is consistent with the real number. The FRA-PARAFAC algorithm is not sensitive to the estimated number of components of the fluorescence data array if the estimated number is not less than the real number. Both algorithms gave identical resolution for the three components concerned DR, EB, and the complex EB-DNA. Variations of the equilibrium concentrations of free DR, EB, and the complex EB-DNA were resolved by both algorithms. Experimental observation confirms the hypothesis that DR is an intercalator of DNA and that the binding interactions of DR and EB with DNA are a pair of parallel competitive intercalation reactions on same base sites of DNA. The method exemplified by this study provides a useful approach for studying competitive interactions of different drugs with DNA in the presence of interferents.

Algorithms↗