170 research outputs found
Missing ophiolitic rocks along the Mae Yuam Fault as the Gondwana-Tethys divide in north-west Thailand
Quantitative relationship between functionally active telomerase and major telomerase components (hTERT and hTR) in acute leukaemia cells
Functionally active telomerase is affected at various steps including transcriptional and post-transcriptional levels of major telomerase components (hTR and human telomerase reverse transcriptase (hTERT)). We therefore developed a rapid and sensitive method to quantify hTERT and its splicing variants as well as the hTR by a Taqman real-time reverse transcriptase–polymerase chain reaction to determine whether their altered expression may contribute to telomere attrition in vivo or not. Fresh leukaemia cells obtained from 38 consecutive patients were used in this study. The enzymatic level of telomerase activity measured by TRAP assay was generally associated with the copy numbers of full-length hTERT+α+β mRNA (P=0.0024), but did not correlate with hTR expression (P=0.6753). In spite of high copy numbers of full-length hTERT mRNA, telomerase activity was low in some cases correlating with low copy numbers of hTR, raising the possibility that alteration of the hTR : hTERT ratio may affect functionally active telomerase activity in vivo. The spliced nonactive hTERT mRNA tends to be lower in patients with high telomerase activity, suggesting that this epiphenomenon may play some role in telomerase regulation. An understanding of the complexities of telomerase gene regulation in biologically heterogeneous leukaemia cells may offer new therapeutic approaches to the treatment of acute leukaemia
Radio emission from Supernova Remnants
The explosion of a supernova releases almost instantaneously about 10^51 ergs
of mechanic energy, changing irreversibly the physical and chemical properties
of large regions in the galaxies. The stellar ejecta, the nebula resulting from
the powerful shock waves, and sometimes a compact stellar remnant, constitute a
supernova remnant (SNR). They can radiate their energy across the whole
electromagnetic spectrum, but the great majority are radio sources. Almost 70
years after the first detection of radio emission coming from a SNR, great
progress has been achieved in the comprehension of their physical
characteristics and evolution. We review the present knowledge of different
aspects of radio remnants, focusing on sources of the Milky Way and the
Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief
overview of theoretical background, analyze morphology and polarization
properties, and review and critical discuss different methods applied to
determine the radio spectrum and distances. The consequences of the interaction
between the SNR shocks and the surrounding medium are examined, including the
question of whether SNRs can trigger the formation of new stars. Cases of
multispectral comparison are presented. A section is devoted to reviewing
recent results of radio SNRs in the Magellanic Clouds, with particular emphasis
on the radio properties of SN 1987A, an ideal laboratory to investigate
dynamical evolution of an SNR in near real time. The review concludes with a
summary of issues on radio SNRs that deserve further study, and analyzing the
prospects for future research with the latest generation radio telescopes.Comment: Revised version. 48 pages, 15 figure
HAPLOINSUFFICIENCY OF TIE2 IN MUTATED BLOOD CELLS SUPPRESS ANGIOGENESIS IN THE BONE MARROW AND INHIBIT PROGRESSION OF MDS
Introduction: Tie2 is a receptor tyrosine kinase and regulates angiogenesis and vascular quiescence. Given that Tie2 modulates microvascular density in cancer, we hypothesized that deletion of Tie2 in blood cells can inhibit progression of myelodysplastic syndrome (MDS). We attempted to understand the role of Tie2 in development of MDS by using an Ezh2/Tet2 double knock out (DKO) mouse model. Methods: We transplanted bone marrow (BM) cells isolated from Cre-ERT2 mice, Tie2flox/wt; Cre-ERT2 mice, Ezh2flox/flox; Tet2flox/flox; Cre-ERT2 mice, Ezh2flox/flox; Tet2flox/flox; Tie2flox/wt; Cre-ERT2 mice and Ezh2flox/flox; Tet2flox/flox; Tie2flox/flox; Cre-ERT2 mice into lethally-irradiated Ly5.1+ recipient mice. Ezh2, Tet2 and Tie2 genes were deleted by administration of tamoxifen one month post the transplantation. Results: We found that Ezh2−/−Tet2−/- DKO, Ezh2−/−Tet2−/- Tie2+/− (DKOTie2+/−) and Ezh2−/−Tet2−/- Tie2−/− TKO mice all developed MDS and MDS/MPN, showing anemia and dysplastic cells in the peripheral blood (PB) and the BM; however, DKOTie2+/− mice showed significantly longer survival than did DKO mice and TKO mice. While DKO mice showed deformed CD31+ endothelial cells and increased vascular density in the BM, DKOTie2+/− mice mitigated the altered vascular formation in the BM. RNA-sequencing revealed that DKOTie2+/− stem cells repressed expression of genes involved in interferon, cell cycles and angiogenesis, compared to DKO stem cells, suggesting that the haploinsufficiency of Tie2 impaired the property of MDS cells to drive angiogenesis in the BM, resulting in the delayed development of MDS. Conclusions: We are now working on the molecular mechanism of how the Tie2 gene in blood cells modulates the angiogenesis to drive the progression of MDS
A piezoelectric single crystal traveling wave step motor for low-temperature application
Utility of Image Fusion System for 3D Preoperative Planning in the Osteosynthesis of Distal Radius Fractures
A novel high thrust–weight ratio linear ultrasonic motor driven by single–phase signal
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