1,844 research outputs found
Readability of Modules and its Relationship with Student Performance in Open Distance Learning (ODL)
Gene expression responses to anti-tuberculous drugs in a whole blood model.
BACKGROUND: There is a need for better tools to evaluate new or repurposed TB drugs. The whole blood bactericidal activity (WBA) assay has been advocated for this purpose. We investigated whether transcriptional responses in the WBA assay resemble TB responses in vivo, and whether the approach might additionally reveal mechanisms of action. RESULTS: 1422 of 1798 (79%) of differentially expressed genes in WBA incubated with the standard combination of rifampicin, isoniazid, pyrazinamide and ethambutol were also expressed in sputum (P < 0.0001) obtained from patients taking the same combination of drugs; these comprised well-established treatment-response genes. Gene expression profiles in WBA incubated with the standard drugs individually, or with moxifloxacin or faropenem (with amoxicillin and clavulanic acid) clustered by individual drug exposure. Distinct pathways were detected for individual drugs, although only with isoniazid did these relate to known mechanisms of drug action. CONCLUSIONS: Substantial agreement between whole blood cultures and sputum and the ability to differentiate individual drugs suggest that transcriptomics may add value to the whole blood assay for evaluating new TB drugs
Depletion of TRRAP induces p53-independent senescence in liver cancer by downregulating mitotic genes
Hepatocellular carcinoma (HCC) is an aggressive subtype of liver cancer with few effective treatments and the underlying mechanisms that drive HCC pathogenesis remain poorly characterized. Identifying genes and pathways essential for HCC cell growth will aid the development of new targeted therapies for HCC. Using a kinome CRISPR screen in three human HCC cell lines, we identified transformation/transcription domain-associated protein (TRRAP) as an essential gene for HCC cell proliferation. TRRAP has been implicated in oncogenic transformation, but how it functions in cancer cell proliferation is not established. Here, we show that depletion of TRRAP or its co-factor, histone acetyltransferase KAT5, inhibits HCC cell growth via induction of p53- and p21-independent senescence. Integrated cancer genomics analyses using patient data and RNA-sequencing identified mitotic genes as key TRRAP/KAT5 targets in HCC, and subsequent cell cycle analyses revealed that TRRAP- and KAT5-depleted cells are arrested at G2/M phase. Depletion of TOP2A, a mitotic gene and TRRAP/KAT5 target, was sufficient to recapitulate the senescent phenotype of TRRAP/KAT5 knockdown. CONCLUSION: Our results uncover a role for TRRAP/KAT5 in promoting HCC cell proliferation via activation of mitotic genes. Targeting the TRRAP/KAT5 complex is a potential therapeutic strategy for HCC
YAP1 withdrawal in hepatoblastoma drives therapeutic differentiation of tumor cells to functional hepatocyte-like cells
BACKGROUND and AIMS: Despite surgical and chemotherapeutic advances, the five-year survival rate for Stage IV Hepatoblastoma (HB), the predominant pediatric liver tumor, remains at 27%. YAP1 and beta-Catenin co-activation occurs in 80% of children\u27s HB; however, a lack of conditional genetic models precludes tumor maintenance exploration. Thus, the need for a targeted therapy remains unmet. Given the predominance of YAP1 and beta-Catenin activation in HB, we sought to evaluate YAP1 as a therapeutic target in HB.
APPROACH and RESULTS: We engineered the first conditional HB murine model using hydrodynamic injection to deliver transposon plasmids encoding inducible YAP1(S127A) , constitutive beta-Catenin(DelN90) , and a luciferase reporter to murine liver. Tumor regression was evaluated using bioluminescent imaging, and tumor landscape characterized using RNA and ATAC sequencing, and DNA foot-printing. Here we show that YAP1(S127A) withdrawal mediates \u3e90% tumor regression with survival for 230+ days in mice. YAP1 (S127A) withdrawal promotes apoptosis in a subset of tumor cells and in remaining cells induces a cell fate switch driving therapeutic differentiation of HB tumors into Ki-67 negative hbHep cells with hepatocyte-like morphology and mature hepatocyte gene expression. YAP1 (S127A) withdrawal drives formation of hbHeps by modulating liver differentiation transcription factor (TF) occupancy. Indeed, tumor-derived hbHeps, consistent with their reprogrammed transcriptional landscape, regain partial hepatocyte function and rescue liver damage in mice.
CONCLUSIONS: YAP1(S127A) withdrawal, without silencing oncogenic beta-Catenin, significantly regresses hepatoblastoma, providing the first in vivo data to support YAP1 as a therapeutic target for HB. YAP1(S127A) withdrawal alone sufficiently drives long-term regression in hepatoblastoma because it promotes cell death in a subset of tumor cells and modulates transcription factor occupancy to reverse the fate of residual tumor cells to mimic functional hepatocytes
Expression of beta defensin genes in frozen thawed and cultured immortalised human corneal epithelial cell line
Human beta defensins (hBD) are important host defense molecules at the ocular surface. In addition to their antimicrobial activities, hBD may also act as regulatory factors in recruiting and activating immune cells. Only hBD-1 – hBD-4 have been well characterised. To date, a complete profile of the beta defensin genes (DEFB) expression in immortalised human corneal epithelial cell line (HCE-2) has not been established. Therefore, this study is aimed to explore a spectrum of DEFB expression in HCE-2. Total RNAs were extracted from frozen thawed HCE-2 and cultured HCE-2 to ensure the gene expression were identical. The RNAs were reverse transcribed into cDNAs. The expression of 10 DEFB (DEFB1, DEFB4A, DEFB103, DEFB104, DEFB105, DEFB106, DEFB109, DEFB123, DEFB126 and DEFB127) were analysed using polymerase chain reaction (PCR) and gel electrophoresis. DEFB1 and DEFB103 were the only hBD mRNAs found constitutively expressed in frozen thawed HCE-2 and cultured HCE-2. It was also interesting to note that PCR enhancer was needed to amplify the genes in cultured HCE-2. Our findings suggest that corneal epithelium constantly produce hBD-1 and hBD-3, which presumably provide the baseline defense against infection. Further investigation on the expression of these genes when HCE-2 stimulated with proinflammatory cytokines would help in better understanding of the ocular surface defense mechanism
Surface reconstruction establishing Mott-Schottky heterojunction and built-in space-charging effect accelerating oxygen evolution reaction
Structural reconstruction of nanomaterials offers a fantastic way to regulate the electronic structure of active sites and promote their catalytic activities. However, how to properly facilitate surface reconstruction to overcome large overpotential that stimulate the surface reconstruction has remained elusive. Herein, we adopt a facile approach to activate surface reconstruction on Ni(OH) 2 by incorporating F anions to achieve electro-derived structural oxidation process and further boost its oxygen evolution reaction (OER) activity. Ex situ Raman and X-ray photoemission spectroscopy studies indicate that F ions incorporation facilitated surface reconstruction and promotes the original Ni(OH) 2 transformed into a mesoporous and amorphous F-NiOOH layer during the electrochemical process. Density functional theory (DFT) calculation reveals that this self-reconstructed NiOOH induces a space-charge effect on the p-n junction interface, which not only promotes the absorption of intermediates species (*OH, *O, and *OOH) and charge-transfer process during catalysis, but also leads to a strong interaction of the p-n junction interface to stabilize the materials. This work opens up a new possibility to regulate the electronic structure of active sites and promote their catalytic activities. [Figure not available: see fulltext.
Interfacial “double-terminal binding sites” catalysts synergistically boosting the electrocatalytic Li2S redox for durable lithium-sulfur batteries
Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium-sulfur (Li-S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li-S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li-S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g-1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm-2 even in challenging conditions with a high sulfur loading (10.7 mg cm-2) and lean electrolyte environments (5.8 μL mg-1). The DTB site strategy offers valuable insights into the development of high-performance Li-S batteries
Fundamentally manipulating the electronic structure of polar bifunctional catalysts for lithium-sulfur batteries: Heterojunction design versus doping engineering
Heterogeneous structures and doping strategies have been intensively used to manipulate the catalytic conversion of polysulfides to enhance reaction kinetics and suppress the shuttle effect in lithium-sulfur (Li-S) batteries. However, understanding how to select suitable strategies for engineering the electronic structure of polar catalysts is lacking. Here, a comparative investigation between heterogeneous structures and doping strategies is conducted to assess their impact on the modulation of the electronic structures and their effectiveness in catalyzing the conversion of polysulfides. These findings reveal that Co0.125Zn0.875Se, with metal-cation dopants, exhibits superior performance compared to CoSe2/ZnSe heterogeneous structures. The incorporation of low Co2+ dopants induces the subtle lattice strain in Co0.125Zn0.875Se, resulting in the increased exposure of active sites. As a result, Co0.125Zn0.875Se demonstrates enhanced electron accumulation on surface Se sites, improved charge carrier mobility, and optimized both p-band and d-band centers. The Li-S cells employing Co0.125Zn0.875Se catalyst demonstrate significantly improved capacity (1261.3 mAh g−1 at 0.5 C) and cycle stability (0.048% capacity delay rate within 1000 cycles at 2 C). This study provides valuable guidance for the modulation of the electronic structure of typical polar catalysts, serving as a design directive to tailor the catalytic activity of advanced Li-S catalysts
A blood RNA transcript signature for TB exposure in household contacts.
BACKGROUND: Current tools for diagnosing latent TB infection (LTBI) detect immunological memory of past exposure but are unable to determine whether exposure is recent. We sought to identify a whole-blood transcriptome signature of recent TB exposure. METHODS: We studied household contacts of TB patients; healthy volunteers without recent history of TB exposure; and patients with active TB. We performed whole-blood RNA sequencing (in all), an interferon gamma release assay (IGRA; in contacts and healthy controls) and PET/MRI lung scans (in contacts only). We evaluated differentially-expressed genes in household contacts (log2 fold change ≥1 versus healthy controls; false-discovery rate 0.19). CONCLUSIONS: Transcriptomics can detect TB exposure and, with further development, may be an approach of value for epidemiological research and targeting public health interventions
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