Biomedical subjects

Xia Gao

Publications and source records attributed to Xia Gao.

23 records · Page 2Linked to original sources

PubMed2003

Structure of nucleotide-binding domain 1 of the cystic fibrosis transmembrane conductance regulator.

Cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-binding cassette (ABC) transporter that functions as a chloride channel. Nucleotide-binding domain 1 (NBD1), one of two ABC domains in CFTR, also contains sites for the predominant CF-causing mutation and, potentially, for regulatory phosphorylation. We have determined crystal structures for mouse NBD1 in unliganded, ADP- and ATP-bound states, with and without phosphorylation. This NBD1 differs from typical ABC domains in having added regulatory segments, a foreshortened subdomain interconnection, and an unusual nucleotide conformation. Moreover, isolated NBD1 has undetectable ATPase activity and its structure is essentially the same independent of ligand state. Phe508, which is commonly deleted in CF, is exposed at a putative NBD1-transmembrane interface. Our results are consistent with a CFTR mechanism, whereby channel gating occurs through ATP binding in an NBD1-NBD2 nucleotide sandwich that forms upon displacement of NBD1 regulatory segments.

Adenosine Diphosphate↗

PubMed2003

Determining a detectable threshold of signal intensity in cDNA microarray based on accumulated distribution.

In microarray data mining, one of the key problems is how to handle weak signals. Based on a bent piecewise linear accumulated distribution generally found in the microarray data, a new detectable threshold finding method is proposed to filter genes with unreliable information in this paper. More reliable and reproducible data is produced for the subsequent data mining.

DNA, Complementary↗

PubMed2003

Universal behavior of localization of residue fluctuations in globular proteins.

Localization properties of residue fluctuations in globular proteins are studied theoretically by using a Gaussian network model. Participation ratio for each residue fluctuation mode is calculated. It is found that the relationship between participation ratio and frequency is similar for all globular proteins, indicating a universal behavior in spite of their different size, shape, and architecture.

Animals↗

PubMed2003

[Heparanase and vascular endothelial growth factor expression in non-small-cell lung cancer].

OBJECTIVE: To study the clinicopathological significance of heparanase and VEGF expression in NSCLC. METHODS: Eighty-five lung samples were studied. Each sample was divided into two parts, one used for heparanase mRNA detection by reverse transcription PCR and the other for VEGF detection by immunohistochemistry. RESULTS: (1) The expressions of heparanase mRNA and VEGF were higher in NSCLC than in benign pulmonary diseases (P < 0.05). (2) The expression of heparanase mRNA was higher in cases with lymph-node invasion, metastasis, stage III and IV diseases, low-differentiation, and adenocarcinoma, as compared to cases without lymph-node invasion and metastasis, with stage I and II diseases, higher and moderate differentiation, and squamous cell cancer (P < 0.05). Its expression was higher in tumors larger than 5 cm in size (P < 0.05). (3) The expression of VEGF was higher in cases with lymph-node invasion, metastasis, and stage III and IV disease, as compared to cases without lymph-node invasion and metastasis, and with stage I and II diseases (P < 0.05). (4) There was no significant correlation between heparanase and VEGF expression (P > 0.05). CONCLUSIONS: Heparanase and VEGF are associated with NSCLC invasion and metastasis, and may be used to evaluate NSCLC metastasis status. Heparanase and VEGF promote NSCLC invasion and metastasis by independent mechanisms. Detection of these two markers may improve the sensitivity and specificity of the measurement of NSCLC metastatic potential.

Adult↗

PubMed2002

[Detection of Rh(D) before blood transfusion and its significance].

The significance of detecting the recipient's Rh D blood type before transfusion and the feasibility of in-time transfusion to Rh D-negative person with the same ABO type blood or autologous blood were explored. For 2,168 inpatients who applied for transfusion for the first time in the latest five years, Rh D-antigen was detected a day before transfusion by test tube method with IgM anti-D serum provided by BASO company. The results showed that seven Rh D-negative cases were found among 2,168 cases and the Rh D-negative rate was 0.32%. Of these seven cases, two were received autologous blood, two were received Rh D-negative blood of the same type and the other three were not treated with transfusion. It is concluded that hemolytic reaction of transfusion was prevented by detecting Rh D blood type before transfusion, autologous transfusion may be taken if the patient's health-condition permits.

ABO Blood-Group System↗