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On page 1 showing 1 ~ 20 papers out of 25 papers

Generalization and fine mapping of European ancestry-based central adiposity variants in African ancestry populations.

  • S Yoneyama‎ et al.
  • International journal of obesity (2005)‎
  • 2017‎

Central adiposity measures such as waist circumference (WC) and waist-to-hip ratio (WHR) are associated with cardiometabolic disorders independently of body mass index (BMI) and are gaining clinically utility. Several studies report genetic variants associated with central adiposity, but most utilize only European ancestry populations. Understanding whether the genetic associations discovered among mainly European descendants are shared with African ancestry populations will help elucidate the biological underpinnings of abdominal fat deposition.


EZH2 contributes to the response to PARP inhibitors through its PARP-mediated poly-ADP ribosylation in breast cancer.

  • H Yamaguchi‎ et al.
  • Oncogene‎
  • 2018‎

Inhibitors against poly (ADP-ribose) polymerase (PARP) are promising targeted agents currently used to treat BRCA-mutant ovarian cancer and are in clinical trials for other cancer types, including BRCA-mutant breast cancer. To enhance the clinical response to PARP inhibitors (PARPis), understanding the mechanisms underlying PARPi sensitivity is urgently needed. Here, we show enhancer of zeste homolog 2 (EZH2), an enzyme that catalyzes H3 lysine trimethylation and associates with oncogenic function, contributes to PARPi sensitivity in breast cancer cells. Mechanistically, upon oxidative stress or alkylating DNA damage, PARP1 interacts with and attaches poly-ADP-ribose (PAR) chains to EZH2. PARylation of EZH2 by PARP1 then induces PRC2 complex dissociation and EZH2 downregulation, which in turn reduces EZH2-mediated H3 trimethylation. In contrast, inhibition of PARP by PARPi attenuates alkylating DNA damage-induced EZH2 downregulation, thereby promoting EZH2-mediated gene silencing and cancer stem cell property compared with PARPi-untreated cells. Moreover, the addition of an EZH2 inhibitor sensitizes the BRCA-mutant breast cells to PARPi. Thus, these results may provide a rationale for combining PARP and EZH2 inhibition as a therapeutic strategy for BRCA-mutated breast and ovarian cancers.


Irsogladine maleate potentiates the effects of nitric oxide on activation of cAMP signalling pathways and suppression of mesangial cell mitogenesis.

  • J Yao‎ et al.
  • British journal of pharmacology‎
  • 2007‎

Deficiency in nitric oxide (NO) is a major factor leading to deterioration and progression of certain glomerular diseases. Agents enhancing NO availability and potentiality are renoprotective. Irsogladine maleate (IM), an anti-ulcer drug, is reported to improve gastric blood flow via NO-dependent mechanisms. We, therefore, asked whether and how IM interacted with NO on glomerular mesangial cells.


The Effect of Maternal Diet with Fish Oil on Oxidative Stress and Inflammatory Response in Sow and New-Born Piglets.

  • W L Luo‎ et al.
  • Oxidative medicine and cellular longevity‎
  • 2019‎

Pregnancy is an oxidative stress and immune challenge for the mother. Fish oil is rich in EPA and DHA, which can partly inhibit aspects of inflammation and restore antioxidant capacity. In the present study, we investigated the effect of maternal diet with fish oil during the late gestation period on oxidative stress and inflammatory response in sows and their progenies. Twelve second-parity sows were allocated equally into two groups. Sows were fed either the soybean oil diet (SD) or soybean oil+fish oil diet (FD) during the gestation period. The plasma of sows, cord blood, and new-born piglets were collected. Full-term placentas and livers of new-born piglets were also sampled. The activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) in the plasma of sows on farrowing day were higher, and the concentrations of interleukin-6 (IL-6) and prostaglandin-endoperoxide synthase 2 (PGE2) in the plasma of sows on farrowing day and interleukin-1β (IL-1β) in the plasma of cord blood were lower in the FD group than those in the SD group (P < 0.05). The FD downregulated the expression of SOD, IL-1β, IL-6, and transforming growth factor-β-activated kinase 1 binding protein 1 (TAB1) mRNA but upregulated the expression of lipoxygenase enzyme 5 (ALOX5) and interleukin-10 (IL-10) mRNA in placentas (P < 0.05). The FD downregulated the protein expression level of p-JNK/JNK in placentas (P < 0.05). In the livers of new-born piglets, the FD upregulated the expression of ALOX5 (P < 0.05) and G-protein-coupled receptor 120 (GPR120) (P < 0.05) mRNA. Our results suggest that the maternal diet with fish oil might alleviate oxidative stress in sows on farrowing day and modulate inflammatory response in full-term placentas by inhibiting the JNK signal pathway. Moreover, the maternal diet with fish oil might partly regulate the neonatal immune response of their progenies.


Overexpression of ErbB2 blocks Taxol-induced apoptosis by upregulation of p21Cip1, which inhibits p34Cdc2 kinase.

  • D Yu‎ et al.
  • Molecular cell‎
  • 1998‎

Overexpression of the receptor tyrosine kinase p185ErbB2 confers Taxol resistance in breast cancers. Here, we investigated the underlying mechanisms and found that overexpression of p185ErbB2 inhibits Taxol-induced apoptosis. Taxol activates p34Cdc2 kinase in MDA-MB-435 breast cancer cells, leading to cell cycle arrest at the G2/M phase and, subsequently, apoptosis. A chemical inhibitor of p34Cdc2 and a dominant-negative mutant of p34Cdc2 blocked Taxol-induced apoptosis in these cells. Overexpression of p185ErbB2 in MDA-MB-435 cells by transfection transcriptionally upregulates p21Cip1, which associates with p34Cdc2, inhibits Taxol-mediated p34Cdc2 activation, delays cell entrance to G2/M phase, and thereby inhibits Taxol-induced apoptosis. In p21Cip1 antisense-transfected MDA-MB-435 cells or in p21-/- MEF cells, p185ErbB2 was unable to inhibit Taxol-induced apoptosis. Therefore, p21Cip1 participates in the regulation of a G2/M checkpoint that contributes to resistance to Taxol-induced apoptosis in p185ErbB2-overexpressing breast cancer cells.


NF-κB and Nrf2 signaling pathways contribute to wogonin-mediated inhibition of inflammation-associated colorectal carcinogenesis.

  • J Yao‎ et al.
  • Cell death & disease‎
  • 2014‎

The transcriptional factors nuclear factor-κB (NF-κB) and NF-E2-related factor 2 (Nrf2) have been recently reported to have critical roles in protecting various tissues against inflammation and colitis-associated colorectal cancer (aberrant crypt foci). Our previous studies showed that wogonin (5,7-dihydroxy-8-methoxyflavone) possessed anti-neoplastic and anti-inflammatory activities. The present study extended these important earlier findings by exploring the effect of wogonin on the initiation and development of colitis-associated cancer. Wogonin lowered tumor incidence and inhibited the development of colorectal adenomas in azoxymethane- or dextran sulfate sodium-induced mice. We found that wogonin significantly decreased the secretion and expression of IL-6 and IL-1β, reduced cell proliferation and nuclear expression of NF-κB in adenomas and surrounding tissues and promoted Nrf2 nuclear translocation in surrounding tissues, although overexpressed Nrf2 in tumor tissues was independent of wogonin administration. Furthermore, wogonin inhibited the interaction between human monocytic THP-1 cells and human colon cancer HCT116 cells, and significantly downregulated lipopolysaccharide-induced secretion of prototypical pro-inflammatory cytokines IL-6 and IL-1β in THP-1 cells. Further mechanism research revealed that wogonin inhibited the nuclear translocation of NF-κB and phosphorylation of IκB and IKKα/β, and promoted Nrf2 signaling pathway in HCT116 cells and THP-1 cells. Taken together, the present results indicated that wogonin effectively suppressed inflammation-associated colon carcinogenesis and cancer development, suggesting its potential as a chemopreventive agent against colitis-associated colon cancer.


Circulating tumour cells as a biomarker for diagnosis and staging in pancreatic cancer.

  • J S Ankeny‎ et al.
  • British journal of cancer‎
  • 2016‎

Current diagnosis and staging of pancreatic ductal adenocarcinoma (PDAC) has important limitations and better biomarkers are needed to guide initial therapy. We investigated the performance of circulating tumour cells (CTCs) as an adjunctive biomarker at the time of disease presentation.


Near Real-Time Implementation of An Adaptive Seismocardiography - ECG Multimodal Framework for Cardiac Gating.

  • J Yao‎ et al.
  • IEEE journal of translational engineering in health and medicine‎
  • 2019‎

Objective: Accurate gating for data acquisition of computed tomography (CT) is crucial to obtaining high quality images for diagnosing cardiovascular diseases. To illustrate the feasibility of an optimized cardiac gating strategy, we present a near real-time implementation based on fusing seismocardiography (SCG) and ECG. Methods: The implementation was achieved via integrating commercial hardware and software platforms. Testing was performed on five healthy subjects (age: 24-27; m/f: 4/1) and three cardiac patients (age: 41-71; m/f: 2/1), and compared with baseline quiescence derived from echocardiography. Results: The average latency introduced by computerized processing was 5.1 ms, well within a 100 ms tolerance bounded by data accumulation time for quiescence prediction. The average prediction error associated with conventional ECG-only versus SCG-ECG-based method over all subjects were 59.58 ms and 27.24 ms, respectively. Discussion: The results demonstrate that the multimodal framework can achieve improved quiescence prediction accuracy over the ECG-only-based method in near real-time.


Tumorigenic potential is restored during differentiation in fusion-reprogrammed cancer cells.

  • J Yao‎ et al.
  • Cell death & disease‎
  • 2016‎

Detailed understanding of the mechanistic steps underlying tumor initiation and malignant progression is critical for insights of potentially novel therapeutic modalities. Cellular reprogramming is an approach of particular interest because it can provide a means to reset the differentiation state of the cancer cells and to revert these cells to a state of non-malignancy. Here, we investigated the relationship between cellular differentiation and malignant progression by the fusion of four independent mouse cancer cell lines from different tissues, each with differing developmental potentials, to pluripotent mouse embryonic stem (ES) cells. Fusion was accompanied by loss of differentiated properties of the four parental cancer cell lines and concomitant emergence of pluripotency, demonstrating the feasibility to reprogram the malignant and differentiative properties of cancer cells. However, the original malignant and differentiative phenotypes re-emerge upon withdrawal of the fused cells from the embryonic environment in which they were maintained. cDNA array analysis of the malignant hepatoma progression implicated a role for Foxa1, and silencing Foxa1 prevented the re-emergence of malignant and differentiation-associated gene expression. Our findings support the hypothesis that tumor progression results from deregulation of stem cells, and our approach provides a strategy to analyze possible mechanisms in the cancer initiation.


Neurons derived from patients with bipolar disorder divide into intrinsically different sub-populations of neurons, predicting the patients' responsiveness to lithium.

  • S Stern‎ et al.
  • Molecular psychiatry‎
  • 2018‎

Bipolar disorder (BD) is a progressive psychiatric disorder with more than 3% prevalence worldwide. Affected individuals experience recurrent episodes of depression and mania, disrupting normal life and increasing the risk of suicide greatly. The complexity and genetic heterogeneity of psychiatric disorders have challenged the development of animal and cellular models. We recently reported that hippocampal dentate gyrus (DG) neurons differentiated from induced pluripotent stem cell (iPSC)-derived fibroblasts of BD patients are electrophysiologically hyperexcitable. Here we used iPSCs derived from Epstein-Barr virus-immortalized B-lymphocytes to verify that the hyperexcitability of DG-like neurons is reproduced in this different cohort of patients and cells. Lymphocytes are readily available for research with a large number of banked lines with associated patient clinical description. We used whole-cell patch-clamp recordings of over 460 neurons to characterize neurons derived from control individuals and BD patients. Extensive functional analysis showed that intrinsic cell parameters are very different between the two groups of BD neurons, those derived from lithium (Li)-responsive (LR) patients and those derived from Li-non-responsive (NR) patients, which led us to partition our BD neurons into two sub-populations of cells and suggested two different subdisorders. Training a Naïve Bayes classifier with the electrophysiological features of patients whose responses to Li are known allows for accurate classification with more than 92% success rate for a new patient whose response to Li is unknown. Despite their very different functional profiles, both populations of neurons share a large, fast after-hyperpolarization (AHP). We therefore suggest that the large, fast AHP is a key feature of BD and a main contributor to the fast, sustained spiking abilities of BD neurons. Confirming our previous report with fibroblast-derived DG neurons, chronic Li treatment reduced the hyperexcitability in the lymphoblast-derived LR group but not in the NR group, strengthening the validity and utility of this new human cellular model of BD.


Isolation, characterization, interaction of a thiazolekinase (Plasmodium falciparum) with silver nanoparticles.

  • J Yao‎ et al.
  • International journal of biological macromolecules‎
  • 2015‎

Malaria, a mosquito-borne infectious disease, is caused by the Plasmodium genus, and remains one of the greatest health challenges worldwide. The malarial parasite possess a biosynthetic pathway for the B-group vitamin incorporating the thiamine metabolizing enzymes; humans on the other hand cannot synthesize the vitamin and require it from within their diet. The vitamin B1 biosynthetic enzyme 5-(2-hydroxyethyl)-4-methylthioazolekinase [EC. 2.7.1.50] from Plasmodium (PfThzK) is particularly attractive as a biomedical target since any inhibition of this enzyme may lead to an effective treatment for malaria. In the present study, PfThzK was recombinantly produced as a 6× His fusion protein in Escherichia coli BL21(DE3) and purified using nickel affinity and size exclusion chromatography. The enzyme was monomeric with a molecular mass of 34 kDa, a specific activity of 295.04 nmol min(-1) mg(-1) and showed an optimum temperature and pH of 37 °C and 7.5, respectively. The purified PfThzK was non-competitively inhibited (79%) by silver nanoparticles (2-6 nm); Ki=6.45 μM. A mechanism is suggested for the interaction of the silver nanoparticle with PfThzK through two sulphur bearing amino acids (Met(1), Cys(206)) on the surface of each subunit of the enzyme.


hsa-miR-520h downregulates ABCG2 in pancreatic cancer cells to inhibit migration, invasion, and side populations.

  • F Wang‎ et al.
  • British journal of cancer‎
  • 2010‎

Expression of ABCG2 is normally absent or low in the pancreas, but high in human pancreatic cancer cells. The mechanism by which ABCG2 is altered in human cancers remains unknown.


Retinoids as a potential treatment for experimental puromycin-induced nephrosis.

  • V Moreno-Manzano‎ et al.
  • British journal of pharmacology‎
  • 2003‎

1 Puromycin aminonucleoside (PAN)-induced nephrosis is a model of human minimal change disease. In rats, PAN induces nephrotic-range proteinuria, renal epithelial cell (podocyte) damage, infiltration of mononuclear leukocytes, and apoptosis of several renal cell types. 2 Retinoic acid (RA) modulates a wide range of biological processes, such as inflammation and apoptosis. Since renal damage by PAN is characterized by inflammatory infiltration and epithelial cell death, the effect of treatment with all-trans RA (tRA) was examined in the PAN nephrosis model and in the cultured differentiated podocyte. 3 Treatment with tRA 4 days after PAN injection did not inhibit the proteinuria peak but reversed it significantly. However, treatment with tRA both before and 2 days after the injection of PAN protected the glomerular epithelial cells, diminishing the cellular edema and diffuseness of the foot process effacement. Preservation of the podocyte architecture correlated with the inhibition of proteinuria. The anti-inflammatory effect of tRA was evidenced by the inhibition of PAN-induced interstitial mononuclear cell infiltration and the decreased renal expression of two molecules involved in monocyte infiltration: fibronectin and monocyte chemoattractant protein-1. TUNEL assays showed that tRA inhibited the PAN-induced apoptosis of cultured differentiated mouse podocytes. 4 We conclude that tRA treatment may prevent proteinuria by protecting the podocytes from injury and diminishing the interstitial mononuclear infiltrate in the model of PAN nephrosis. Retinoids are a potential new treatment for kidney diseases characterized by proteinuria and mononuclear cell infiltration.


Functional relationship between subfornical organ cholinergic stimulation and cellular activation in the hypothalamus and AV3V region.

  • Z Xu‎ et al.
  • Brain research‎
  • 2001‎

The subfornical organ (SFO) has been suggested to be important for water intake and secretion of vasopressin (AVP). However, the role of the SFO cholinergic mechanism in the control of body fluid regulation is not clear. This study determined the effects of local cholinergic stimulation in the SFO produced by administration of physostigmine on drinking and cellular excitation in the anterior third ventricle (AV3V) region and in the supraoptic and paraventricular nuclei (SON and PVN). The results showed that injection of physostigmine into the SFO induced water intake and c-fos expression in the AV3V area as well as in the AVP containing neurons in the hypothalamus. Pretreatment of the SFO with mecamylamine, a nicotinic receptor antagonist, had no effect on physostigmine induced behavioral and c-fos responses. The muscarinic receptor blocker atropine, however, abolished both drinking and cellular activation after injection of physostigmine into the SFO. Immunostaining experiments demonstrated positive acetyltransferase (ChAT) in the SFO. Intensive ChAT immunoreactivity was located in the cholinergic fibers in the SFO. Together, the results indicate that SFO cholinergic mechanisms are important in co-operation with the AV3V and hypothalamic neurons in the control of thirst and AVP-mediated body fluid homeostasis.


Role of long non-coding RNA-RNCR3 in atherosclerosis-related vascular dysfunction.

  • K Shan‎ et al.
  • Cell death & disease‎
  • 2016‎

Atherosclerosis is one of the most common vascular disorders. Endothelial cell (EC) dysfunction and vascular smooth muscle cell (VSMC) proliferation contributes to the development of atherosclerosis. Long non-coding RNAs (lncRNAs) have been implicated in several biological processes and human diseases. Here we show that lncRNA-RNCR3 is expressed in ECs and VSMCs. RNCR3 expression is significantly upregulated in mouse and human aortic atherosclerotic lesions, and cultured ECs and VSMCs upon ox-LDL treatment in vitro. RNCR3 knockdown accelerates the development of atherosclerosis, aggravates hypercholesterolemia and inflammatory factor releases, and decreases EC and VSMC proliferation in vivo. RNCR3 knockdown also reduces the proliferation and migration, and accelerates apoptosis development of EC and VSMC in vitro. RNCR3 acts as a ceRNA, and forms a feedback loop with Kruppel-like factor 2 and miR-185-5p to regulate cell function. This study reveals that RNCR3 has an atheroprotective role in atherosclerosis, and its intervention is a promising strategy for treating atherosclerosis-related vascular dysfunction.


Linking genomic reorganization to tumor initiation via the giant cell cycle.

  • N Niu‎ et al.
  • Oncogenesis‎
  • 2016‎

To investigate the mechanisms underlying our recent paradoxical finding that mitotically incapacitated and genomically unstable polyploid giant cancer cells (PGCCs) are capable of tumor initiation, we labeled ovarian cancer cells with α-tubulin fused to green fluorescent protein, histone-2B fused to red fluorescent protein and FUCCI (fluorescent ubiquitination cell cycle indicator), and tracked the spatial and time-dependent change in spindle and chromosomal dynamics of PGCCs using live-cell fluorescence time-lapse recording. We found that single-dose (500 nm) treatment with paclitaxel paradoxically initiated endoreplication to form PGCCs after massive cell death. The resulting PGCCs continued self-renewal via endoreplication and further divided by nuclear budding or fragmentation; the small daughter nuclei then acquired cytoplasm, split off from the giant mother cells and acquired competency in mitosis. FUCCI showed that PGCCs divided via truncated endoreplication cell cycle (endocycle or endomitosis). Confocal microscopy showed that PGCCs had pronounced nuclear fragmentation and lacked expression of key mitotic proteins. PGCC-derived daughter cells were capable of long-term proliferation and acquired numerous new genome/chromosome alterations demonstrated by spectral karyotyping. These data prompt us to conceptualize a giant cell cycle composed of four distinct but overlapping phases, initiation, self-renewal, termination and stability. The giant cell cycle may represent a fundamental cellular mechanism to initiate genomic reorganization to generate new tumor-initiating cells in response to chemotherapy-induced stress and contributes to disease relapse.


Role of microRNA508-3p in melanogenesis by targeting microphthalmia transcription factor in melanocytes of alpaca.

  • J Zhang‎ et al.
  • Animal : an international journal of animal bioscience‎
  • 2017‎

It has been demonstrated that microRNAs (miRNAs) play important roles in the control of melanogenesis and hair color in mammals. By comparing miRNA expression profiles between brown and white alpaca skin, we previously identified miR508-3p as a differentially expressed miRNA suggesting its potential role in melanogenesis and hair color formation. The present study was conducted to determine the role of miR508-3p in melanogenesis in alpaca melanocytes. In situ hybridization showed that miR508-3p is abundantly present in the cytoplasma of alpaca melanocytes. miR508-3p was predicted to target the gene encoding microphthalmia transcription factor (MITF) and a luciferase reporter assay indicated that miR508-3p regulates MITF expression by directly targeting its 3'UTR. Overexpression of miR508-3p in alpaca melanocytes down-regulated MITF expression both at the messenger RNA and protein level and resulted in decreased expression of key melanogenic genes including tyrosinase and tyrosinase-related protein 2. Overexpression of miR508-3p in melanocytes also resulted in decreased melanin production including total alkali-soluble melanogenesis, eumelanogenesis and pheomelanogenesis. Results support a functional role of miR508-3p in regulating melanogenesis in alpaca melanocytes by directly targeting MITF.


Selective inhibition of protein kinase C β2 attenuates the adaptor P66 Shc-mediated intestinal ischemia-reperfusion injury.

  • Z Chen‎ et al.
  • Cell death & disease‎
  • 2014‎

Apoptosis is a major mode of cell death occurring during ischemia-reperfusion (I/R) induced injury. The p66(Shc) adaptor protein, which is mediated by PKCβ, has an essential role in apoptosis under oxidative stress. This study aimed to investigate the role of PKCβ2/p66(Shc) pathway in intestinal I/R injury. In vivo, ischemia was induced by superior mesenteric artery occlusion in mice. Ruboxistaurin (PKCβ inhibitor) or normal saline was administered before ischemia. Then blood and gut tissues were collected after reperfusion for various measurements. In vitro, Caco-2 cells were challenged with hypoxia-reoxygenation (H/R) to simulate intestinal I/R. Translocation and activation of PKCβ2 were markedly induced in the I/R intestine. Ruboxistaurin significantly attenuated gut damage and decreased the serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Pharmacological blockade of PKCβ2 suppressed p66(Shc) overexpression and phosphorylation in the I/R intestine. Gene knockdown of PKCβ2 via small interfering RNA (siRNA) inhibited H/R-induced p66(Shc) overexpression and phosphorylation in Caco-2 cells. Phorbol 12-myristate 13-acetate (PMA), which stimulates PKCs, induced p66(Shc) phosphorylation and this was inhibited by ruboxistaurin and PKCβ2 siRNA. Ruboxistaurin attenuated gut oxidative stress after I/R by suppressing the decreased expression of manganese superoxide dismutase (MnSOD), the exhaustion of the glutathione (GSH) system, and the overproduction of malondialdehyde (MDA). As a consequence, ruboxistaurin inhibited intestinal mucosa apoptosis after I/R. Therefore, PKCβ2 inhibition protects mice from gut I/R injury by suppressing the adaptor p66(Shc)-mediated oxidative stress and subsequent apoptosis. This may represent a novel therapeutic approach for the prevention of intestinal I/R injury.


Leptin changes differentiation fate and induces senescence in chondrogenic progenitor cells.

  • X Zhao‎ et al.
  • Cell death & disease‎
  • 2016‎

Body weight is a component of the mechanical theory of OA (osteoarthritis) pathogenesis. Obesity was also found to be a risk factor for digital OA involving non-weight-bearing joints, which suggested that metabolism influences the occurrence and progression of OA. The metabolic origin of OA has been partially attributed to the involvement of adipokines, such as leptin, the levels of which are significantly and positively correlated with cartilage degeneration in OA patients. However, the mechanisms by which leptin-induced cartilage degeneration occurs are poorly understood. The discovery of chondrogenic progenitor cells (CPCs) opened up new opportunities for investigation. Investigating the effects of leptin on differentiation and proliferation in CPCs would increase our understanding of the roles played by leptin in the aetiology and development of OA. Here, CPCs were harvested using single-cell sorting from rat cartilage tissues to obtain mesenchymal stem-like cells, which possess clonogenicity, proliferation and stemness. High doses of leptin decreased the ability of the CPCs to migrate, inhibited their chondrogenic potential and increased their osteogenic potential, suggesting that leptin changes differentiation fates in CPCs. High doses of leptin induced cell cycle arrest and senescence in CPCs by activating the p53/p21 pathway and inhibiting the Sirt1 pathway. Inhibiting the Sirt1 pathway accelerated cartilage senescence in knockout (KO) mice. Activating the leptin pathway induced higher Ob-Rb expression and was significantly correlated with cartilage degeneration (lower levels of Coll-2) and tissue senescence (higher levels of p53/p21 and lower levels of Sirt1) in OA patients, suggesting that leptin-induced CPCs senescence contributes to the development of OA. Taken together, our results reveal new links between obesity and cartilage damage that are induced by leptin-mediated effects on cell behaviour and senescence.


Spectroscopic Investigation of the Effect of Microstructure and Energetic Offset on the Nature of Interfacial Charge Transfer States in Polymer: Fullerene Blends.

  • S D Dimitrov‎ et al.
  • Journal of the American Chemical Society‎
  • 2019‎

Despite performance improvements of organic photovoltaics, the mechanism of photoinduced electron-hole separation at organic donor-acceptor interfaces remains poorly understood. Inconclusive experimental and theoretical results have produced contradictory models for electron-hole separation in which the role of interfacial charge-transfer (CT) states is unclear, with one model identifying them as limiting separation and another as readily dissociating. Here, polymer-fullerene blends with contrasting photocurrent properties and enthalpic offsets driving separation were studied. By modifying composition, film structures were varied from consisting of molecularly mixed polymer-fullerene domains to consisting of both molecularly mixed and fullerene domains. Transient absorption spectroscopy revealed that CT state dissociation generating separated electron-hole pairs is only efficient in the high energy offset blend with fullerene domains. In all other blends (with low offset or predominantly molecularly mixed domains), nanosecond geminate electron-hole recombination is observed revealing the importance of spatially localized electron-hole pairs (bound CT states) in the electron-hole dynamics. A two-dimensional lattice exciton model was used to simulate the excited state spectrum of a model system as a function of microstructure and energy offset. The results could reproduce the main features of experimental electroluminescence spectra indicating that electron-hole pairs become less bound and more spatially separated upon increasing energy offset and fullerene domain density. Differences between electroluminescence and photoluminescence spectra could be explained by CT photoluminescence being dominated by more-bound states, reflecting geminate recombination processes, while CT electroluminescence preferentially probes less-bound CT states that escape geminate recombination. These results suggest that apparently contradictory studies on electron-hole separation can be explained by the presence of both bound and unbound CT states in the same film, as a result of a range of interface structures.


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