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Articles by L Zhou
Total Records ( 18 ) for L Zhou
  J Huang , J Gao , X Lv , G Li , D Hao , X Yao , L Zhou , D Liu and R. Wang

Glioma-specific transcription of tumor-killing genes has been exploited as a promising gene therapeutic modality in glioma patients. Musashi1 (Msi1) and GFAP gene promoters are both cancer-specific promoters. Optimized HIF-binding site (optHBS) sequence was newly found as efficient as EPO HREs used as enhancer in cancer gene therapy. We constructed 4optHBS-Msi1/GFAP promoters and tested their ability to mediate BAX expression to induce apoptosis in glioma cell lines. Our results demonstrated that 4optHBS-Msi1/GFAP promoters are apparently strong and glioma-selective promoters with potential application in targeted glioma gene therapy, and 4optHBS-Msi1/GFAP-BAX are valuable tools for glioma gene therapy.

  W Zhu , D Czyzyk , S. A Paranjape , L Zhou , A Horblitt , G Szabo , M. R Seashore , R. S Sherwin and O. Chan

Local delivery of glucose into a critical glucose-sensing region within the brain, the ventromedial hypothalamus (VMH), can suppress glucose counterregulatory responses to systemic hypoglycemia. Here, we investigated whether this suppression was accomplished through changes in GABA output in the VMH. Sprague-Dawley rats had catheters and guide cannulas implanted. Eight to ten days later, microdialysis-microinjection probes were inserted into the VMH, and they were dialyzed with varying concentrations of glucose from 0 to 100 mM. Two groups of rats were microdialyzed with 100 mM glucose and microinjected with either the KATP channel opener diazoxide or a GABAA receptor antagonist. These animals were then subjected to a hyperinsulinemic-hypoglycemic glucose clamp. As expected, perfusion of glucose into the VMH suppressed the counterregulatory responses. Extracellular VMH GABA levels positively correlated with the concentration of glucose in the perfusate. In turn, extracellular GABA concentrations in the VMH were inversely related to the degree of counterregulatory hormone release. Of note, microinjection of either diazoxide or the GABAA receptor antagonist reversed the suppressive effects of VMH glucose delivery on counterregulatory responses. Some GABAergic neurons in the VMH respond to changes in local glucose concentration. Glucose in the VMH dose-dependently stimulates GABA release, and this in turn dose-dependently suppresses the glucagon and epinephrine responses to hypoglycemia. These data suggest that during hypoglycemia a decrease in glucose concentration within the VMH may provide an important signal that rapidly inactivates VMH GABAergic neurons, reducing inhibitory GABAergic tone, which in turn enhances the counterregulatory responses to hypoglycemia.

  X Fan , Y Ding , S Brown , L Zhou , M Shaw , M. C Vella , H Cheng , E. C McNay , R. S Sherwin and R. J. McCrimmon
  In nondiabetic rodents, AMP-activated protein kinase (AMPK) plays a role in the glucose-sensing mechanism used by the ventromedial hypothalamus (VMH), a key brain region involved in the detection of hypoglycemia. However, AMPK is regulated by both hyper- and hypoglycemia, so whether AMPK plays a similar role in type 1 diabetes (T1DM) is unknown. To address this issue, we used four groups of chronically catheterized male diabetic BB rats, a rodent model of autoimmune T1DM with established insulin—requiring diabetes (40 ± 4 pmol/l basal c-peptide). Two groups were subjected to 3 days of recurrent hypoglycemia (RH), while the other two groups were kept hyperglycemic [chronic hyperglycemia (CH)]. All groups subsequently underwent hyperinsulinemic hypoglycemic clamp studies on day 4 in conjunction with VMH microinjection with either saline (control) or AICAR (5-aminoimidazole-4-carboxamide) to activate AMPK. Compared with controls, local VMH application of AICAR during hypoglycemia amplified both glucagon [means ± SE, area under the curve over time (AUC/t) 144 ± 43 vs. 50 ± 11 ng·l–1·min–1; P < 0.05] and epinephrine [4.27 ± 0.96 vs. 1.06 ± 0.26 nmol·l–1·min–1; P < 0.05] responses in RH-BB rats, and amplified the glucagon [151 ± 22 vs. 85 ± 22 ng·l–1·min–1; P < 0.05] response in CH-BB rats. We conclude that VMH AMPK also plays a role in glucose-sensing during hypoglycemia in a rodent model of T1DM. Moreover, our data suggest that it may be possible to partially restore the hypoglycemia-specific glucagon secretory defect characteristic of T1DM through manipulation of VMH AMPK.
  L Zhou , R. A Palais , G. D Smith , D Anderson , L. R Rowe and C. T. Wittwer

Background: Selective amplification of minority alleles is often necessary to detect cancer mutations in clinical samples.

Methods: Minor-allele enrichment and detection were performed with snapback primers in the presence of a saturating DNA dye within a closed tube. A 5' tail of nucleotides on 1 PCR primer hybridizes to the variable locus of its extension product to produce a hairpin that selectively enriches mismatched alleles. Genotyping performed after rapid-cycle PCR by melting of the secondary structure identifies different variants by the hairpin melting temperature (Tm). Needle aspirates of thyroid tissue (n = 47) and paraffin-embedded biopsy samples (n = 44) were analyzed for BRAF (v-raf murine sarcoma viral oncogene homolog B1) variant p.V600E, and the results were compared with those for dual hybridization probe analysis. Needle aspirates of lung tumors (n = 8) were analyzed for EGFR [epidermal growth factor receptor (erythroblastic leukemia viral (v-erb-b) oncogene homolog, avian)] exon 19 in-frame deletions.

Results: Use of 18-s cycles and momentary extension times of "0 s" with rapid-cycle PCR increased the selective amplification of mismatched alleles. A low Mg2+ concentration and a higher hairpin Tm relative to the extension temperature also improved the detection limit of mismatched alleles. The detection limit was 0.1% for BRAF p.V600E and 0.02% for EGFR exon 19 in-frame deletions. Snapback and dual hybridization probe methods for allele quantification of the thyroid samples correlated well (R2 = 0.93) with 2 more BRAF mutations (45 and 43, respectively, of 91 samples) detected after snapback enrichment. Different EGFR in-frame deletions in the lung samples produced different hairpin Tms.

Conclusions: Use of snapback primers for enrichment and detection of minority alleles is simple, is inexpensive to perform, and can be completed in a closed tube in <25 min.

  L Zhou , B Zheng , A Wei , B Geller and J. Cui

The support for multiple high-definition video streams in wireless home networks requires appropriate routing and rate control measures, ascertaining the reasonable links for transmitting each stream and the rate of the video to be delivered over the chosen links. In this paper, we invest the combination of the routing and rate control in a united convex optimization formulation and propose a distributed joint solution based on cross-layer design. We first develop a distortion model which captures both the impact of encoder quantization and packet loss due to network congestion on the overall video quality. Then, the optimal joint rate control and routing scheme is realized by adapting its rate to the time-varying traffic and minimizing the overall network congestion. Furthermore, simulation results are provided, which demonstrate the effectiveness of our proposed joint routing and rate control scheme in the context of wireless home networks.

  C Li , Z Chen , Z Liu , J Huang , W Zhang , L Zhou , D. L Keefe and L. Liu

Mammalian parthenogenetic embryos (pE) are not viable due to placental deficiency, presumably resulting from lack of paternally expressed imprinted genes. Pluripotent parthenogenetic embryonic stem (pES) cells derived from pE could advance regenerative medicine by avoiding immuno-rejection and ethical roadblocks. We attempted to explore the epigenetic status of imprinted genes in the generation of pES cells from parthenogenetic blastocysts, and its relationship to pluripotency of pES cells. Pluripotency was evaluated for developmental and differentiation potential in vivo, based on contributions of pES cells to chimeras and development to day 9.5 of pES fetuses complemented by tetraploid embryos (TEC). Consistently, pE and fetuses failed to express paternally expressed imprinted genes, but pES cells expressed those genes in a pattern resembling that of fertilized embryos (fE) and fertilized embryonic stem (fES) cells derived from fE. Like fE and fES cells, but unlike pE or fetuses, pES cells and pES cell–fetuses complemented by TEC exhibited balanced methylation of Snrpn, Peg1 and U2af1-rs1. Coincidently, global methylation increased in pE but decreased in pES cells, further suggesting dramatic epigenetic reprogramming occurred during isolation and culture of pES cells. Moreover, we identified decreased methylation of Igf2r, Snrpn, and especially U2af1-rs1, in association with increased contributions of pES cells to chimeras. Our data show that in vitro culture changes epigenetic status of imprinted genes during isolation of pES cells from their progenitor embryos and that increased expression of U2af1-rs1 and Snrpn and decreased expression of Igf2r correlate with pluripotency of pES cells.

  Y Ding , L Jiao , W Zhang , L Zhou , X Zhang and L. Zhang

Sucrose is a convenient, common, tissue-equivalent material suitable for electron paramagnetic resonance (EPR) dosimetry of ionising radiation. A number of publications have reported on the dosimetric properties of sucrose and their use in radiation accident dose reconstruction. However, previous studies did not include specially the description of measurement methods of sucrose by EPR. The aim of this work is to introduce particularly the EPR measurement methods of sucrose. In this regard, practical considerations of sample size, microwave power, modulation amplitude, EPR spectrum and signal stability are discussed.

  D Iwakiri , L Zhou , M Samanta , M Matsumoto , T Ebihara , T Seya , S Imai , M Fujieda , K Kawa and K. Takada

Epstein-Barr virus–encoded small RNA (EBER) is nonpolyadenylated, noncoding RNA that forms stem-loop structure by intermolecular base-pairing, giving rise to double-stranded RNA (dsRNA)–like molecules, and exists abundantly in EBV-infected cells. Here, we report that EBER induces signaling from the Toll-like receptor 3 (TLR3), which is a sensor of viral double-stranded RNA (dsRNA) and induces type I IFN and proinflammatory cytokines. A substantial amount of EBER, which was sufficient to induce signaling from TLR3, was released from EBV-infected cells, and the majority of the released EBER existed as a complex with a cellular EBER-binding protein La, suggesting that EBER was released from the cells by active secretion of La. Sera from patients with infectious mononucleosis (IM), chronic active EBV infection (CAEBV), and EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH), whose general symptoms are caused by proinflammatory cytokines contained EBER, and addition of RNA purified from the sera into culture medium induced signaling from TLR3 in EBV-transformed lymphocytes and peripheral mononuclear cells. Furthermore, DCs treated with EBER showed mature phenotype and antigen presentation capacity. These findings suggest that EBER, which is released from EBV-infected cells, is responsible for immune activation by EBV, inducing type I IFN and proinflammatory cytokines. EBER-induced activation of innate immunity would account for immunopathologic diseases caused by active EBV infection.

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