Biomedical subjects

Xiaolong Liu

Publications and source records attributed to Xiaolong Liu.

7 recordsLinked to original sources

PubMed2006

Constructing a novel Nanodevice powered by delta-free FoF1-ATPase.

A Nanodevice was constructed by delta-free F(o)F(1)-ATPase within chromatophores and actin filaments through biotinlipid-streptavidin-biotin-(AC(5))(2)Sulfo-OSu system. One actin filament linking with many chromatophores functions as the Nanodevice body and many delta-free F(o)F(1)-ATPase as the Nanodevice motors. Movement of the Nanodevice was observed directly by fluorescence microscopy with CCD camera after illumination. The moving speed was about 2.17-24.43mum/s for various length Nanodevices and most of them were stopped by adding CCCP. This means that the Nanodevice was driven by PMF (proton-motive force) in the cooperating delta-free F(o)F(1)-ATPase. From bioengineering point of view, the cooperation of F(o)F(1)-ATPase is a very important research field in the future.

Actins↗

PubMed2006

F0F1-ATPase as biosensor to detect single virus.

F(0)F(1)-ATPase within chromatophore was constructed as a biosensor (immuno-rotary biosensor) for the purpose of capturing single virus. Capture of virus was based on antibody-antigen reaction. The detection of virus based on proton flux change driven by ATP-synthesis of F(0)F(1)-ATPase, which was indicated by F1300, was directly observed by a fluorescence microscope. The results demonstrate that the biosensor loading of virus particles has remarkable signal-to-noise ratio (3.8:1) compared to its control at single molecular level, and will be convenient, quick, and even super-sensitive for detecting virus particles.

Biosensing Techniques↗

PubMed2005

Analyzing expression of perforin, Runx3, and Thpok genes during positive selection reveals activation of CD8-differentiation programs by MHC II-signaled thymocytes.

Intrathymic positive selection matches CD4-CD8 lineage differentiation to MHC specificity. However, it is unclear whether MHC signals induce lineage choice or simply select thymocytes of the appropriate lineage. To investigate this issue, we assessed thymocytes undergoing positive selection for expression of the CD8 lineage markers perforin and Runx3. Using both population-based and single-cell RT-PCR analyses, we found large subsets of MHC class II (MHC-II)-signaled thymocytes expressing these genes within the CD4+ 8+ and CD4+ 8(int), but not the CD4+ 8- populations of signaling competent mice. This indicates that MHC-II signals normally fail to impose CD4 differentiation and further implies that the number of mature CD8 single-positive (SP) thymocytes greatly underestimates CD8 lineage choice. We next examined whether MHC-II-restricted CD4+ 8- thymocytes remain competent to initiate CD8 lineage gene expression. In mice in which expression of the tyrosine kinase Zap70 and thereby TCR signaling were impaired selectively in SP thymocytes, MHC-II-signaled CD4+ 8- thymocytes expressed perforin and Runx3 and failed to up-regulate the CD4 marker Thpok. This indicated that impairing TCR signals at the CD4 SP stage switched gene expression patterns from CD4- to CD8-lineage specific. We conclude from these findings that MHC-II-signaled thymocytes remain competent to initiate CD8-specific gene expression even after CD8 down-regulation and that CD4 lineage differentiation is not fixed before the CD4 SP stage.

Animals↗

PubMed2005

The zinc finger protein cKrox directs CD4 lineage differentiation during intrathymic T cell positive selection.

The genetic programs directing CD4 or CD8 T cell differentiation in the thymus remain poorly understood. While analyzing gene expression during intrathymic T cell selection, we found that Zfp67, encoding the zinc finger transcription factor cKrox, was upregulated during the differentiation of CD4(+) but not CD8(+) T cells. Expression of a cKrox transgene impaired CD8 T cell development and caused major histocompatibility complex class I-restricted thymocytes to differentiate into CD4(+) T cells with helper properties rather than into cytotoxic CD8(+) T cells, as normally found. CD4 lineage differentiation mediated by cKrox required its N-terminal BTB (bric-a-brac, tramtrack, broad complex) domain. These findings identify cKrox as a chief CD4 differentiation factor during positive selection.

Animals↗

PubMed2004

Duration of TCR signaling controls CD4-CD8 lineage differentiation in vivo.

The duration of T cell receptor (TCR) signaling is thought to be important for thymocyte differentiation into the CD4 or CD8 lineage. However, the in vivo relevance of this hypothesis is unclear. Here we divided T cell positive selection into genetically separable developmental steps by confining TCR signal transduction to discrete thymocyte developmental windows. TCR signals confined to the double-positive thymocyte stage promoted CD8, but not CD4, lineage differentiation. Major histocompatibility complex (MHC) class II-restricted thymocytes were, instead, redirected into the CD8 lineage. These findings support the hypothesis that distinct kinetics of MHC class I- and MHC class II-induced TCR signals direct intrathymic developmental decisions.

Animals↗

PubMed2003

Restricting Zap70 expression to CD4+CD8+ thymocytes reveals a T cell receptor-dependent proofreading mechanism controlling the completion of positive selection.

Although T cell receptor (TCR) signals are essential for intrathymic T cell-positive selection, it remains controversial whether they only serve to initiate this process, or whether they are required throughout to promote thymocyte differentiation and survival. To address this issue, we have devised a novel approach to interfere with thymocyte TCR signaling in a developmental stage-specific manner in vivo. We have reconstituted mice deficient for Zap70, a tyrosine kinase required for TCR signaling and normally expressed throughout T cell development, with a Zap70 transgene driven by the adenosine deaminase (ADA) gene enhancer, which is active in CD4(+)CD8(+) thymocytes but inactive in CD4(+) or CD8(+) single-positive (SP) thymocytes. In such mice, termination of Zap70 expression impaired TCR signal transduction and arrested thymocyte development after the initiation, but before the completion, of positive selection. Arrested thymocytes had terminated Rag gene expression and up-regulated TCR and Bcl-2 expression, but failed to differentiate into mature CD4 or CD8 SP thymocytes, to be rescued from death by neglect or to sustain interleukin 7R alpha expression. These observations identify a TCR-dependent proofreading mechanism that verifies thymocyte TCR specificity and differentiation choices before the completion of positive selection.

Adenosine Deaminase↗

PubMed2003

[Clinical analysis of 48 cases with Mondini dysplasia].

OBJECTIVE: To improve the ability to diagnosis the Mondini dysplasis, 48 cases of Mondini dysplasis were reported. METHOD: The clinical data of 48 cases were collected. The clinical manifestation and the examination of CT and MRI and treatment of the Mondini dysplasia were discussed. RESULT: Most of them were deaf when they were babies. The prolonged speaking and unsteading were important clinical feature. CONCLUSION: The diagnosis of the disease is based on the examination of the hight resolution tomography and magnetic resonance image of the temporal bone. Hearing aid is common management to the disease. A part of patients should be considered cochlear implantation.

Adolescent↗