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排序方式: 共有127条查询结果,搜索用时 19 毫秒
1.
Deepak Poudyal Xiangli Cui Phuong Mai Le Anne B. Hofseth Anthony Windust Mitzi Nagarkatti Prakash S. Nagarkatti Aaron J. Schetter Curtis C. Harris Lorne J. Hofseth 《PloS one》2013,8(10)
Metastasis of colon cancer cells increases the risk of colon cancer mortality. We have recently shown that American ginseng prevents colon cancer, and a Hexane extract of American Ginseng (HAG) has particularly potent anti-inflammatory and anti-cancer properties. Dysregulated microRNA (miR) expression has been observed in several disease conditions including colon cancer. Using global miR expression profiling, we observed increased miR-29b in colon cancer cells following exposure to HAG. Since miR-29b plays a role in regulating the migration of cancer cells, we hypothesized that HAG induces miR-29b expression to target matrix metalloproteinase-2 (MMP-2) thereby suppressing the migration of colon cancer cells. Results are consistent with this hypothesis. Our study supports the understanding that targeting MMP-2 by miR-29b is a mechanism by which HAG suppresses the migration of colon cancer cells. 相似文献
2.
Fill Factor Losses in Cu2ZnSn(SxSe1−x)4 Solar Cells: Insights from Physical and Electrical Characterization of Devices and Exfoliated Films 下载免费PDF全文
Kong Fai Tai Oki Gunawan Masaru Kuwahara Shi Chen Subodh Gautam Mhaisalkar Cheng Hon Alfred Huan David B. Mitzi 《Liver Transplantation》2016,6(3)
Besides the open circuit voltage (VOC) deficit, fill factor (FF) is the second most significant parameter deficit for earth‐abundant kesterite solar cell technology. Here, various pathways for FF loss are discussed, with focus on the series resistance issue and its various contributing factors. Electrical and physical characterizations of the full range of bandgap (Eg = 1.0–1.5 eV) Cu2ZnSn(SxSe1?x)4 (CZTSSe) devices, as well as bare and exfoliated films with various S/(S + Se) ratios, are performed. High intensity Suns‐VOC measurement indicates a nonohmic junction developing in high bandgap CZTSSe. Grazing incidence X‐ray diffraction, Raman mapping, field emission scanning electron microscopy, and X‐ray photoelectron spectroscopy indicate the formation of Sn(S,Se)2, Mo(S,Se)2, and Zn(S,Se) at the high bandgap CZTSSe/Mo interface, contributing to the increased series resistance (RS) and nonohmic back contact characteristics. This study offers some clues as to why the record‐CZTSSe solar cells occur within a bandgap range centered around 1.15 eV and offers some direction for further optimization. 相似文献
3.
With power conversion efficiencies now exceeding 25%, hybrid perovskite solar cells require deeper understanding of defects and processing to further approach the Shockley‐Queisser limit. One approach for processing enhancement and defect reduction involves additive engineering—, e.g., addition of MASCN (MA = methylammonium) and excess PbI2 have been shown to modify film grain structure and improve performance. However, the underlying impact of these additives on transport and recombination properties remains to be fully elucidated. In this study, a newly developed carrier‐resolved photo‐Hall (CRPH) characterization technique is used that gives access to both majority and minority carrier properties within the same sample and over a wide range of illumination conditions. CRPH measurements on n‐type MAPbI3 films reveal an order of magnitude increase in carrier recombination lifetime and electron density for 5% excess PbI2 added to the precursor solution, with little change noted in electron and hole mobility values. Grain size variation (120–2100 nm) and MASCN addition induce no significant change in carrier‐related parameters considered, highlighting the benign nature of the grain boundaries and that excess PbI2 must predominantly passivate bulk defects rather than defects situated at grain boundaries. This study offers a unique picture of additive impact on MAPbI3 optoelectronic properties as elucidated by the new CRPH approach. 相似文献
4.
CD44-deficient mice exhibit enhanced hepatitis after concanavalin A injection: evidence for involvement of CD44 in activation-induced cell death 总被引:9,自引:0,他引:9
Chen D McKallip RJ Zeytun A Do Y Lombard C Robertson JL Mak TW Nagarkatti PS Nagarkatti M 《Journal of immunology (Baltimore, Md. : 1950)》2001,166(10):5889-5897
Administration of Con A induces severe injury to hepatocytes in mice and is considered to be a model for human hepatitis. In the current study, we investigated the role of CD44 in Con A-induced hepatitis. Intravenous administration of Con A (20 mg/kg) caused 100% mortality in C57BL/6 CD44-knockout (KO) mice, although it was not lethal in C57BL/6 CD44 wild-type (WT) mice. Administration of lower doses of Con A (12 mg/kg body weight) into CD44 WT mice induced hepatitis as evident from increased plasma aspartate aminotransferase levels accompanied by active infiltration of mononuclear cells and neutrophils, and significant induction of apoptosis in the liver. Interestingly, CD44 KO mice injected with similar doses of Con A exhibited more severe acute suppurative hepatitis. Transfer of spleen cells from Con A-injected CD44 KO mice into CD44 WT mice induced higher levels of hepatitis when compared with transfer of similar cells from CD44 WT mice into CD44 WT mice. The increased hepatitis seen in CD44 KO mice was accompanied by increased production of cytokines such as TNF-alpha, IL-2 and IFN-gamma, but not Fas or Fas ligand. The increased susceptibility of CD44 KO mice to hepatitis correlated with the observation that T cells from CD44 KO mice were more resistant to activation-induced cell death when compared with the CD44 WT mice. Together, these data demonstrate that activated T cells use CD44 to undergo apoptosis, and dysregulation in this pathway could lead to increased pathogenesis in a number of diseases, including hepatitis. 相似文献
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McKallip RJ Fisher M Do Y Szakal AK Gunthert U Nagarkatti PS Nagarkatti M 《The Journal of biological chemistry》2003,278(44):43818-43830
In the current study, we investigated the nature and role of CD44 variant isoforms involved in endothelial cell (EC) injury and tumor cell cytotoxicity mediated by IL-2-activated killer (LAK) cells. Treatment of CD44 wild-type lymphocytes with IL-2 led to increased gene expression of CD44 v6 and v7 variant isoforms and to significant induction of vascular leak syndrome (VLS). CD44v6-v7 knockout (KO) and CD44v7 KO mice showed markedly reduced levels of IL-2-induced VLS. The decreased VLS in CD44v6-v7 KO and CD44v7 KO mice did not result from differential activation and expansion of CD8+ T cells, NK, and NK-T cells or from altered degree of perivascular lymphocytic infiltration in the lungs. LAK cells from CD44v7 KO mice showed a significant decrease in their ability to adhere to and mediate lysis of EC but not lysis of P815 tumor cells in vitro. CD44v7-mediated lysis of EC by LAK cells was dependent on the activity of phosphatidylinositol 3-kinase and tyrosine kinases. Interestingly, IL-2-activated LAK cells expressing CD44hi but not CD44lo were responsible for EC lysis. Furthermore, lysis of EC targets could be blocked by addition of soluble or enzymatic cleavage of CD44v6-v7-binding glycosaminoglycans. Finally, anti-CD44v7 mAbs caused a significant reduction in the adherence to and killing of EC and led to suppression of IL-2-induced VLS. Together, this study suggests that the expression of CD44v7 on LAK cells plays a specific role in EC injury and that it may be possible to reduce EC injury but not tumor cell killing by specifically targeting CD44v7. 相似文献
8.
During a survey for natural enemies of thegrape berry moth (GBM) Endopiza viteana(Clemens) in northwestern Pennsylvania, wefound that Trichogramma minutum Riley isthe only native egg parasitoid with thepotential to limit berry damage by preventingegg hatch. Natural parasitism, however, wasfound to be unreliable for providing economicpest suppression. Early season populations ofthe parasitoid are extremely low and may be theresult of inadequate alternative host eggs foroverwintering. Also, wild grapes and theirwooded habitats were found to be favored byT. minutum. Parasitism was low incultivated grapes and in wild grapes growingclose to commercial vineyards (possibly due tothe deterrent effect of insecticides) andhighest in sites 1.5 km from commercialvineyards. Adult T. minutum emergingfrom GBM eggs were exceptionally small andshowed little vigor. Parasitized eggs oftenfailed to produce adult parasitoids. Pre-adults in such eggs had poorly formed mouth-parts or lacked them altogether. Inundativereleases of laboratory-reared T. minutumin border rows of vineyards are suggested as apossible alternative to the current practice ofapplying carbamate and organophosphateinsecticides, which are inimical to beneficialarthropods. 相似文献
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Tumor-derived Fas ligand induces toxicity in lymphoid organs and plays an important role in successful chemotherapy 总被引:7,自引:0,他引:7
Nagarkatti N 《Cancer immunology, immunotherapy : CII》2000,49(1):46-55
Recent studies have suggested that Fas ligand (FasL+) tumor cells can induce apoptosis in Fas+ T cells. However, the effect of growth of FasL+ tumors in vivo, on lymphoid tissues of the host is not clear and therefore was the subject of this investigation. Injection
of FasL+ LSA tumor caused a significant decrease in cellularity of the thymus and spleen, resulting from marked apoptosis, in syngeneic
C57BL/6+/+ (wild-type) but not C57BL/6-lpr/lpr (Fas-deficient) mice. The tumor-induced toxicity resulted from tumor-derived rather than host-derived FasL, inasmuch as LSA
tumor growth in C57BL/6-gld/gld (FasL-defective) mice, induced marked apoptosis and toxicity in the thymus and spleen. The LSA tumor growth induced a significant
decrease in the percentage of CD4+CD8+ T cells in the thymus of C57BL/6+/+ mice and an increase in the percentage of CD4+, CD8+ and CD4−CD8− T cells. Of the four subpopulations tested, the CD4+CD8+ T cells showed maximum apoptosis. The LSA (FasL+) but not P815(FasL−) tumor cell lysates and culture supernatants induced marked apoptosis in Fas+ thymocytes, when tested both in vitro and in vivo. The LSA-tumor-induced apoptosis in vitro was inhibited by antibodies against
FasL or by caspase and other inhibitors of apoptosis. Chemotherapy of LSA-tumor-bearing C57BL/6+/+ mice at advanced stages
of tumor growth failed to cure the mice, whereas, more than 80% of LSA-tumor-bearing C57BL/6-lpr/lpr mice, similarly treated, survived. Together, the current study demonstrates that FasL produced by LSA tumor cells is functional
in vivo and can cause severe toxicity in lymphoid organs of the host. Also, Fas/FasL interactions may play an important role
in the successful chemotherapy of FasL-bearing tumor.
Received: 31 August 1999 / Accepted: 12 November 1999 相似文献