Most genetic variants identified for type 2 diabetes have been discovered in European populations. We performed genome-wide association studies (GWAS) in a Chinese population with the aim of identifying novel variants for type 2 diabetes in Asians.
We performed a meta-analysis of three GWAS comprising 684 patients with type 2 diabetes and 955 controls of Southern Han Chinese descent. We followed up the top signals in two independent Southern Han Chinese cohorts (totalling 10,383 cases and 6,974 controls), and performed in silico replication in multiple populations.
We identified CDKN2A/B and four novel type 2 diabetes association signals with p < 1 × 10−5 from the meta-analysis. Thirteen variants within these four loci were followed up in two independent Chinese cohorts, and rs10229583 at 7q32 was found to be associated with type 2 diabetes in a combined analysis of 11,067 cases and 7,929 controls (pmeta = 2.6 × 10−8; OR [95% CI] 1.18 [1.11, 1.25]). In silico replication revealed consistent associations across multiethnic groups, including five East Asian populations (pmeta = 2.3 × 10−10) and a population of European descent (p = 8.6 × 10−3). The rs10229583 risk variant was associated with elevated fasting plasma glucose, impaired beta cell function in controls, and an earlier age at diagnosis for the cases. The novel variant lies within an islet-selective cluster of open regulatory elements. There was significant heterogeneity of effect between Han Chinese and individuals of European descent, Malaysians and Indians.
Our study identifies rs10229583 near PAX4 as a novel locus for type 2 diabetes in Chinese and other populations and provides new insights into the pathogenesis of type 2 diabetes.
Electronic supplementary material
The online version of this article (doi:10.1007/s00125-013-2874-4) contains peer-reviewed but unedited supplementary material, which is available to authorised users.
Chinese; Diabetes; East Asians; Genetics; Genome-wide association study
c-Met represents an important emerging therapeutic target in cancer. Here, we demonstrate the mechanism by which c-Met tyrosine kinase inhibition inhibits tumor growth in a highly invasive Asian-prevalent head and neck cancer, nasopharyngeal cancer (NPC). c-Met tyrosine kinase inhibitors (TKIs; AM7 and c-Met TKI tool compound SU11274) downregulated c-Met phosphorylation resulting in markedly inhibited growth and invasion of NPC cells. Strikingly, inhibition of c-Met resulted in marked downregulation of TIGAR (TP53-induced Glycolysis and Apoptosis Regulator) and subsequent depletion of intracellular NADPH. Importantly, overexpression of TIGAR ameliorated the effects of c-Met kinase inhibition, confirming the importance of TIGAR downregulation in growth inhibition induced by c-Met TKI. The effects of c-Met inhibition on TIGAR and NADPH levels were observed with two different c-Met TKIs (AM7 and SU11274) and with multiple cell lines. As NADPH provides a crucial reducing power required for cell survival and proliferation, our findings represent a novel mechanistic action of c-Met TKI, which may represent a key effect of c-Met kinase inhibition. Our data provides the first evidence linking c-Met, TIGAR and NADPH regulation in human cancer cells suggesting that inhibition of a tyrosine kinase/TIGAR/NADPH cascade may have therapeutic applicability in human cancers.
c-Met tyrosine kinase inhibitor; TIGAR; NADPH
The iminodiacetate dianion in the title compound, [Zn(C4H5NO4)(C12H8N2)(H2O)]·1.5H2O, chelates to the ZnII center with its N and two O atoms. The metal atom is also chelated by the N-heterocycle and coordinated by one water molecule, leading to a distorted octahedral environment. The dianion, and coordinated and uncoordinated water molecules interact through O—H⋯O hydrogen bonds, generating a three-dimensional network. One of the two uncoordinated water molecules has half-site occupancy. The crystal studied was a non-merohedral twin with a 15% twin component.
The iminodiacetate dianion in the title compound, [Co(C4H5NO4)(C12H8N2)(H2O)]·H2O, chelates to the cobalt(II) atom, its N and two O atoms occupying the fac sites of the distorted octahedron around the metal atom. The metal atom is also chelated by the N-heterocycle. The dianion, and coordinated and uncoordinated water molecules interact through hydrogen bonds, generating a layer motif. The crystal studied was a racemic twin with a 0.62 (2):0.38 (2) domain ratio.
Bone remodeling is intrinsically regulated by cell signaling molecules. The Protein Kinase C (PKC) family of serine/threonine kinases is involved in multiple signaling pathways including cell proliferation, differentiation, apoptosis and osteoclast biology. However, the precise involvement of individual PKC isoforms in the regulation of osteoclast formation and bone homeostasis remains unclear. Here, we identify PKC-δ as the major PKC isoform expressed among all PKCs in osteoclasts; including classical PKCs (−α, −β and −γ), novel PKCs (−δ, −ε, −η and −θ) and atypical PKCs (−ι/λ and −ζ). Interestingly, pharmacological inhibition and genetic ablation of PKC-δ impairs osteoclastic bone resorption in vitro. Moreover, disruption of PKC-δ activity protects against LPS-induced osteolysis in mice, with osteoclasts accumulating on the bone surface failing to resorb bone. Treatment with the PKC-δ inhibitor Rottlerin, blocks LPS-induced bone resorption in mice. Consistently, PKC-δ deficient mice exhibit increased trabeculae bone containing residual cartilage matrix, indicative of an osteoclast-rich osteopetrosis phenotype. Cultured ex vivo osteoclasts derived from PKC-δ null mice exhibit decreased CTX-1 levels and MARKS phosphorylation, with enhanced formation rates. This is accompanied by elevated gene expression levels of cathepsin K and PKC −α, −γ and −ε, as well as altered signaling of pERK and pcSrc416/527 upon RANKL-induction, possibly to compensate for the defects in bone resorption. Collectively, our data indicate that PKC-δ is an intrinsic regulator of osteoclast formation and bone resorption and thus is a potential therapeutic target for pathological osteolysis.
This study sought to test the hypothesis that “virtual” electrophysiologic studies (EPS) on an anatomic platform generated by 3D MRI reconstruction of the left ventricle (LV) can reproduce the reentrant circuits of induced ventricular tachycardia (VT) in a porcine model of myocardial infarction (MI).
Delayed-enhancement MRI has been used to characterize MI and “gray zones”, which are thought to reflect heterogeneous regions of viable and non-viable myocytes.
MI by coronary artery occlusion was induced in eight pigs. After a recovery period, 3D cardiac MRIs were obtained from each pig in-vivo. Normal areas, gray zones, and infarct cores were classified based on voxel intensity. In the computer model, gray zones were assigned slower conduction and longer action potential durations than those for normal myocardium. Virtual EPS was performed and was compared to results of actual in vivo programmed stimulation and non-contact mapping.
The LV volumes ranged from 97.8 to 166.2 cm3 with 4.9 to 17.5% of voxels classified as infarct zones. Six of the seven pigs that developed VT during actual EPS were also inducible with virtual EPS. Four of the six pigs that had simulated VT had reentrant circuits that approximated the circuits seen with non-contact mapping, while the remaining two had similar circuits but propagating in opposite directions.
This initial study demonstrates the feasibility of applying a mathematical model to MRI reconstructions of the LV to predict VT circuits. Virtual EPS may be helpful to plan catheter ablation strategies or to identify patients who are at risk for future episodes of VT.
Ventricular tachycardia; computer-based model; myocardial infarction; magnetic resonance imaging
Type 2 diabetes (T2D) is a complex disease characterized by beta cell dysfunctions. Islet amyloid polypeptide (IAPP) is highly conserved and co-secreted with insulin with over 40% of autopsy cases of T2D showing islet amyloid formation due to IAPP aggregation. Dysregulation in IAPP processing, stabilization and degradation can cause excessive oligomerization with beta cell toxicity. Previous studies examining genetic associations of pathways implicated in IAPP metabolism have yielded conflicting results due to small sample size, insufficient interrogation of gene structure and gene-gene interactions. In this multi-staged study, we screened 89 tag single nucleotide polymorphisms (SNPs) in 6 candidate genes implicated in IAPP metabolism and tested for independent and joint associations with T2D and beta cell dysfunctions. Positive signals in the stage-1 were confirmed by de novo and in silico analysis in a multi-centre unrelated case-control cohort. We examined the association of significant SNPs with quantitative traits in a subset of controls and performed bioinformatics and relevant functional analyses. Amongst the tag SNPs, rs1583645 in carboxypeptidase E (CPE) and rs6583813 in insulin degrading enzyme (IDE) were associated with 1.09 to 1.28 fold increased risk of T2D (PMeta = 9.4×10−3 and 0.02 respectively) in a meta-analysis of East Asians. Using genetic risk scores (GRS) with each risk variant scoring 1, subjects with GRS≥3 (8.2% of the cohort) had 56% higher risk of T2D than those with GRS = 0 (P = 0.01). In a subcohort of control subjects, plasma IAPP increased and beta cell function index declined with GRS (P = 0.008 and 0.03 respectively). Bioinformatics and functional analyses of CPE rs1583645 predicted regulatory elements for chromatin modification and transcription factors, suggesting differential DNA-protein interactions and gene expression. Taken together, these results support the importance of dysregulation of IAPP metabolism in T2D in East Asians.
Western countries, prostate cancer is the most prevalent cancer of men, and one of the leading causes of cancer-related death in men. Several genome-wide association studies have yielded numerous common variants conferring risk of prostate cancer. In the present study we analyzed 32.5 million variants discovered by whole-genome sequencing 1,795 Icelanders. One variant was found to be associated with prostate cancer in European populations: rs188140481[A] (OR = 2.90, Pcomb = 6.2×10−34) located on 8q24, with an average risk allele control frequency of 0.54%. This variant is only very weakly correlated (r2 ≤ 0.06) with previously reported risk variants on 8q24, and remains significant after adjustment for all of them. Carriers of rs188140481[A] were diagnosed with prostate cancer 1.26 years younger than non-carriers (P = 0.0059). We also report results for the previously described HOXB13 mutation (rs138213197[T]), confirming it as prostate cancer risk variant in populations from all over Europe.
Ovarian cancer is the leading cause of mortality from gynecological malignancy despite advancements in novel therapeutics. We have recently demonstrated that the transcriptional co-repressor C-terminal binding protein 2 (CtBP2) is overexpressed in epithelial ovarian carcinoma.
Materials and Methods
Reverse-transcribed cDNA from CtBP2 wild-type and knockdown ovarian cancer cell lines was hybridized to Affymetrix Gene 1.0 ST microarrays, and differentially expressed genes were studied. Immunohistochemical analysis of CtBP2 and BRCA1 staining of ovarian tissues was performed. Chromatin immunoprecipitation (ChIP) and luciferase assays were carried out. The effect of the drugs 4-methylthio-2-oxobutyric acid (MTOB) and poly(ADP-ribose) polymerase (PARP) inhibitor Olaparib on CtBP2 wild-type and knockdown cell lines was examined using methylthiazol tetrazolium assays and an xCELLigence System.
Eighty-five genes involved in DNA repair, mitotic checkpoint, nucleosome assembly, and the BRCA1 network were differentially regulated by CtBP2 expression. ChIP and luciferase reporter assays using a BRCA1 promoter-regulated luciferase construct indicated that the CtBP2 complex binds the BRCA1 promoter and represses BRCA1 transcription. Immunohistochemistry illustrated a significant inverse CtBP2 and BRCA1 expression in a panel of malignant ovarian tumor tissues. The CtBP2 inhibitor MTOB suppressed ovarian cancer cell survival in a CtBP2-dependent manner. Ovarian cancer cells with CtBP2 knockdown did not display increased sensitivity to the PARP inhibitor Olaparib.
CtBP2 is an ovarian cancer oncogene that may play a significant role in epigenetically silencing BRCA1 function in sporadic epithelial ovarian cancer. CtBP2-specific inhibitors, such as MTOB, may be effective adjunct therapies in the management of patients with CtBP2-positive ovarian carcinoma.
A comparative analysis of the genomic and replication profiles of different geographical chikungunya virus (CHIKV) isolates of the East, Central and South African (ECSA) lineage was performed.
Analysis of the data revealed the different growth kinetics for the different isolates. Deep genome sequencing analysis further revealed specific amino acid mutations in the viral nsP1, nsP3, nsP4, E1 and E2 proteins in the different isolates. Despite the difference in viral genomic profiles, the virus-induced ultrastructural changes within infected cells remained highly conserved among the different chikungunya virus isolates.
These findings provide insights into the genomic and replication profiles of the re-emerging chikungunya virus isolates of the ECSA lineage.
Chikungunya virus; Genome sequencing; Virus morphogenesis; Virus replication kinetics
Embryonic stem cell (ESC) pluripotency is governed by a gene regulatory network centered on the transcription factors Oct4 and Nanog. To date, robust self-renewing ESC states have only been obtained through the chemical inhibition of signaling pathways or enforced transgene expression. Here, we show that ESCs with reduced Oct4 expression resulting from heterozygosity also exhibit a stabilized pluripotent state. Despite having reduced Oct4 expression, Oct4+/− ESCs show increased genome-wide binding of Oct4, particularly at pluripotency-associated enhancers, homogeneous expression of pluripotency transcription factors, enhanced self-renewal efficiency, and delayed differentiation kinetics. Cells also exhibit increased Wnt expression, enhanced leukemia inhibitory factor (LIF) sensitivity, and reduced responsiveness to fibroblast growth factor. Although they are able to maintain pluripotency in the absence of bone morphogenetic protein, removal of LIF destabilizes pluripotency. Our findings suggest that cells with a reduced Oct4 concentration range are maintained in a robust pluripotent state and that the wild-type Oct4 concentration range enables effective differentiation.
•Reduced Oct4 results in homogeneous transcription factor level and delayed differentiation kinetics•Oct4+/− ESCs show increased Oct4 and Nanog binding at pluripotency enhancers•Oct4+/− ESCs exhibit increased Wnt, phospho-STAT3, and LIF sensitivity•Reduced Oct4 levels robustly maintain ESC pluripotency without BMP/serum/2i
Reduced Oct4 expression leads to increased Oct4 and Nanog binding to key pluripotency network sites, altered signaling responses that favor self-renewal, and a stabilized pluripotent state that inhibits differentiation.
Hepatocellular carcinoma (HCC) is one the the most fatal cancers worldwide. The poor prognosis of HCC is mainly due to the developement of distance metastasis. To investigate the mechanism of metastasis in HCC, an orthotopic HCC metastasis animal model was established. Two sets of primary liver tumor cell lines and corresponding lung metastasis cell lines were generated. In vitro functional analysis demonstrated that the metastatic cell line had higher invasion and migration ability when compared with the primary liver tumor cell line. These cell lines were subjected to microRNA (miRNAs) microarray analysis to identify differentially expressed miRNAs which were associated with the developement of metastasis in vivo. Fifteen human miRNAs, including miR-106b, were differentially expressed in 2 metastatic cell lines compared with the primary tumor cell lines. The clinical significance of miR-106b in 99 HCC clinical samples was studied. The results demonstrated that miR-106b was over-expressed in HCC tumor tissue compared with adjacent non-tumor tissue (p = 0.0005), and overexpression of miR-106b was signficantly correlated with higher tumor grade (p = 0.018). Further functional studies demonstrated that miR-106b could promote cell migration and stress fiber formation by over-expressing RhoGTPases, RhoA and RhoC. In vivo functional studies also showed that over-expression of miR-106b promoted HCC metastasis. These effects were related to the activation of the epithelial-mesenchymal transition (EMT) process. Our results suggested that miR-106b expression contributed to HCC metastasis by activating the EMT process promoting cell migration in vitro and metastasis in vivo.
The defect of the melatonin signaling pathway has been proposed to be one of the key etiopathogenic factors in adolescent idiopathic scoliosis (AIS). A previous report showed that melatonin receptor, MT2, was undetectable in some AIS girls. The present study aimed to investigate whether the abnormal MT2 expression in AIS is quantitative or qualitative. Cultured osteoblasts were obtained from 41 AIS girls and nine normal controls. Semi-quantification of protein expression by Western blot and mRNA expression by TaqMan real-time PCR for both MT1 and MT2 were performed. Anthropometric parameters were also compared and correlated with the protein expression and mRNA expression of the receptors. The results showed significantly lower protein and mRNA expression of MT2 in AIS girls compared with that in normal controls (p = 0.02 and p = 0.019, respectively). No differences were found in the expression of MT1. When dichotomizing the AIS girls according to their MT2 expression, the group with low expression was found to have a significantly longer arm span (p = 0.036). The results of this study showed for the first time a quantitative change of MT2 in AIS that was also correlated with abnormal arm span as part of abnormal systemic skeletal growth.
idiopathic scoliosis; melatonin; receptors; osteoblasts
Recent studies suggest HIV-1 inter-subtype differences in co-receptor usage. We examined the correlation between HIV-1 subtype and co-receptor usage among treatment-naïve HIV-1 subjects in Singapore. Additionally, we investigated whether the subtype co-receptor association was influenced by stage of infection.
V3 sequences of HIV-1 envelope protein gp120 were obtained from 110 HIV treatment-naïve patients and genotypic co-receptor tropism determination was performed using Geno2pheno. Two false-positive rate (FPR) cut-offs, 10% and 5.75% were selected for tropism testing.
Subtype assignment of viral strains from 110 HIV-infected individuals based on partial sequencing of HIV-1 pol, gp120 and gp41 were as follows: 27 subtype B, 64 CRF01_AE, 10 CRF51_01B, and 9 other subtypes. At FPR=10%, 10 (100%) CRF51_01B-infected subjects and 26 (40.6%) CRF01_AE-infected subjects had CXCR4-using virus, compared to 7 (25.9%) subtype B subjects and 1 (11.1%) CRF33_01B-infected subject (P < 0.001). At FPR=5.75%, 10 (100%) CRF51_01B-infected subjects and 20 (31.3%) CRF01_AE-infected subjects had CXCR4-using virus, compared to 4 (14.8%) subtype B and 1 (11.1%) CRF33_01B-infected subjects (P < 0.001). Among those with evidence of seroconversion within 2 years prior to study enrolment, 100% of CRF51_01B-infected subjects had CXCR4-using virus, independent of Geno2pheno FPR.
CRF51_01B and CRF01_AE-infected individuals have higher prevalence of CXCR4-usage compared to subtype B infected individuals. Further studies examining these differences could help optimise the use of CCR5-antagonist in populations with these subtypes, and increase our understanding of HIV-1 biology.
CXCR4 usage; HIV-1; treatment-naïve
Chikungunya virus (CHIKV) is an arthropod-borne virus responsible for recent epidemics in the Asia Pacific regions. A customized gene expression microarray of 18,760 transcripts known to target Aedes mosquito genome was used to identify host genes that are differentially regulated during the infectious entry process of CHIKV infection on C6/36 mosquito cells. Several genes such as epsin I (EPN1), epidermal growth factor receptor pathway substrate 15 (EPS15) and Huntingtin interacting protein I (HIP1) were identified to be differentially expressed during CHIKV infection and known to be involved in clathrin-mediated endocytosis (CME). Transmission electron microscopy analyses further revealed the presence of CHIKV particles within invaginations of the plasma membrane, resembling clathrin-coated pits. Characterization of vesicles involved in the endocytic trafficking processes of CHIKV revealed the translocation of the virus particles to the early endosomes and subsequently to the late endosomes and lysosomes. Treatment with receptor-mediated endocytosis inhibitor, monodansylcadaverine and clathrin-associated drug inhibitors, chlorpromazine and dynasore inhibited CHIKV entry, whereas no inhibition was observed with caveolin-related drug inhibitors. Inhibition of CHIKV entry upon treatment with low-endosomal pH inhibitors indicated that low pH is essential for viral entry processes. CHIKV entry by clathrin-mediated endocytosis was validated via overexpression of a dominant-negative mutant of Eps15, in which infectious entry was reduced, while siRNA-based knockdown of genes associated with CME, low endosomal pH and RAB trafficking proteins exhibited significant levels of CHIKV inhibition. This study revealed, for the first time, that the infectious entry of CHIKV into mosquito cells is mediated by the clathrin-dependent endocytic pathway.
Deciphering the much neglected aspects of cellular factors in contributing to the infectious entry of CHIKV into mosquito cells may enhance our understanding of the conservation or diversity of these host factors amongst mammalian and arthropod for successful CHIKV replication. The study revealed that the infectious entry of chikungunya virus (CHIKV) into mosquito cells is mediated by the clathrin-dependent endocytic pathway. A customized gene expression microarray known to target the Aedes mosquito genome was used to identify host genes that are differentially regulated upon CHIKV infection. A combination of bio-imaging studies and pharmacological inhibitors confirmed the involvement of clathrin-mediated endocytosis as well as the importance of low endosomal pH during CHIKV infectious entry. Furthermore, the clathrin heavy chain, Eps15, RAB5, RAB7 and vacuolar ATPase B are shown to be essential for the infectious entry process of CHIKV. This study aims to underline the importance of cellular factors, particularly those associated with clathrin-dependent endocytosis, in mediating the infectious entry of CHIKV into mosquito cells.
Catabacter hongkongensis is a recently described catalase-positive, motile, anaerobic, nonsporulating, Gram-positive coccobacillus that was first isolated from blood cultures of four patients from Hong Kong and Canada. Although DNA sequences representing C. hongkongensis have been detected in environmental sources, only one additional case of human infection has been reported, in France. We describe five cases of C. hongkongensis bacteremia in Hong Kong, two presenting with sepsis, one with acute gangrenous perforated appendicitis, one with acute calculous cholecystitis, and one with infected carcinoma of colon. Three patients, with gastrointestinal malignancy, died during admission. All five isolates were catalase positive, motile, and negative for indole production and nitrate reduction and produced acid from arabinose, glucose, mannose, and xylose. They were unambiguously identified as C. hongkongensis by 16S rRNA gene analysis. Of the total of 10 reported cases of C. hongkongensis bacteremia in the literature and this study, most patients had underlying diseases, while two cases occurred in healthy young individuals with acute appendicitis. Six patients presented with infections associated with either the gastrointestinal or biliary tract, supporting the gastrointestinal tract as the source of bacteremia. C. hongkongensis bacteremia is associated with a poor prognosis, with a high mortality of 50% among reported cases, especially in patients with advanced malignancies. All reported isolates were susceptible to metronidazole. Identification of more C. hongkongensis isolates by 16S rRNA gene sequencing will help better define its epidemiology and pathogenesis.
Dectin-1 (CLEC7A) is a C-type lectin receptor that binds to β-glucans found in fungal cell walls to act as a major pattern recognition receptor (PRR). Since β-glucans epitope is not present in human cells, we are of the opinion that Dectin-1 can have therapeutic functions against fungal infections. We thus set out to produce a soluble extracellular domain of murine Dectin-1 (called sDectin-1) in sufficient titers to facilitate such studies in mouse models. Since sDectin-1 has previously been shown to be glycosylated, we chose to produce this protein using Chinese Hamster Ovary (CHO) cells, a mammalian host cell line suitable for the high-titer production of recombinant glycoproteins. To ensure a high titer production of sDectin-1 and minimize the effects of gene fragmentation, we constructed a mammalian expression vector with a PEST-destabilized dhfr amplifiable marker downstream of an attenuated IRES element, which was in turn downstream of the sDectin-1 gene and a CMV IE promoter. Stably transfected and MTX-amplified cell pools were generated using this vector, and maximum sDectin-1 titers of 246 mg/l and 598 mg/l were obtained in shake flask batch culture and bioreactor fed-batch culture respectively. The purified recombinant sDectin-1 was shown to be glycosylated. Protein functionality was also demonstrated by its ability to bind to zymosan particles and to the cell wall of Saccharomyces cerevisiae. We describe for the first time the use of an attenuated IRES-linked PEST-destabilized dhfr amplifiable marker for the production of recombinant proteins with stably amplified cell pools. With our process, we reached the highest reported titer for producing recombinant proteins smaller than 50 kDa in cell pools. sDectin-1 protein produced is glycosylated and functional. This vector design can thus be used efficiently for the high-titer production of functional recombinant proteins.
An accurate early warning system to predict impending epidemics enhances the effectiveness of preventive measures against dengue fever. The aim of this study was to develop and validate a forecasting model that could predict dengue cases and provide timely early warning in Singapore.
Methodology and Principal Findings
We developed a time series Poisson multivariate regression model using weekly mean temperature and cumulative rainfall over the period 2000–2010. Weather data were modeled using piecewise linear spline functions. We analyzed various lag times between dengue and weather variables to identify the optimal dengue forecasting period. Autoregression, seasonality and trend were considered in the model. We validated the model by forecasting dengue cases for week 1 of 2011 up to week 16 of 2012 using weather data alone. Model selection and validation were based on Akaike's Information Criterion, standardized Root Mean Square Error, and residuals diagnoses. A Receiver Operating Characteristics curve was used to analyze the sensitivity of the forecast of epidemics. The optimal period for dengue forecast was 16 weeks. Our model forecasted correctly with errors of 0.3 and 0.32 of the standard deviation of reported cases during the model training and validation periods, respectively. It was sensitive enough to distinguish between outbreak and non-outbreak to a 96% (CI = 93–98%) in 2004–2010 and 98% (CI = 95%–100%) in 2011. The model predicted the outbreak in 2011 accurately with less than 3% possibility of false alarm.
We have developed a weather-based dengue forecasting model that allows warning 16 weeks in advance of dengue epidemics with high sensitivity and specificity. We demonstrate that models using temperature and rainfall could be simple, precise, and low cost tools for dengue forecasting which could be used to enhance decision making on the timing, scale of vector control operations, and utilization of limited resources.
Without effective drugs or a vaccine, vector control remains the only method of controlling dengue fever outbreaks in Singapore. Based on our previous findings on the effects of weather on dengue cases and optimal timing for issuing dengue early warning in Singapore, the purpose of this study was to develop a dengue forecasting model that would provide early warning of a dengue outbreak several months in advance to allow sufficient time for effective control to be implemented. We constructed a statistical model using weekly mean temperature and rainfall. This involved 1) identifying the optimal lag period for forecasting dengue cases; 2) developing the model that described past dengue distribution patterns; 3) performing sensitivity tests to analyze whether the selected model could detect actual outbreaks. Finally, we used the selected model to forecast dengue cases from 2011–2012 week16 using weather data alone. Our model forecasted for a period of 16 weeks with high sensitivity in distinguishing between an outbreak and a non-outbreak. We conclude that weather can be an important factor for providing early warning of dengue epidemics, long term sustainability of forecast precision is challenging considering the complex dynamics of disease transmission.
A dengue early warning system aims to prevent a dengue outbreak by providing an accurate prediction of a rise in dengue cases and sufficient time to allow timely decisions and preventive measures to be taken by local authorities. This study seeks to identify the optimal lead time for warning of dengue cases in Singapore given the duration required by a local authority to curb an outbreak.
Methodology and Findings
We developed a Poisson regression model to analyze relative risks of dengue cases as functions of weekly mean temperature and cumulative rainfall with lag times of 1–5 months using spline functions. We examined the duration of vector control and cluster management in dengue clusters > = 10 cases from 2000 to 2010 and used the information as an indicative window of the time required to mitigate an outbreak. Finally, we assessed the gap between forecast and successful control to determine the optimal timing for issuing an early warning in the study area. Our findings show that increasing weekly mean temperature and cumulative rainfall precede risks of increasing dengue cases by 4–20 and 8–20 weeks, respectively. These lag times provided a forecast window of 1–5 months based on the observed weather data. Based on previous vector control operations, the time needed to curb dengue outbreaks ranged from 1–3 months with a median duration of 2 months. Thus, a dengue early warning forecast given 3 months ahead of the onset of a probable epidemic would give local authorities sufficient time to mitigate an outbreak.
Optimal timing of a dengue forecast increases the functional value of an early warning system and enhances cost-effectiveness of vector control operations in response to forecasted risks. We emphasize the importance of considering the forecast-mitigation gaps in respective study areas when developing a dengue forecasting model.
A dengue early warning system that would provide an accurate forecast could enhance the effectiveness of dengue control, but only if it is given in sufficient time for local authorities to implement those control operations. In this study, we have suggested the optimal timing for issuing a warning of a dengue outbreak in Singapore that will allow authorities adequate time to respond. We first analyzed the relationship between the risk of dengue cases and weather predictors at 1–5 month lag times to gauge the possible lead time for providing an accurate dengue forecast. We then determined the average time needed for local authorities to curb the outbreak of clusters of 10 dengue cases or more using vector control and cluster duration records for the period 2000–2010. Increasing weekly mean temperature and cumulative rainfall preceded a rise in dengue cases up to 5 months with higher risks evident at a lag time of 3–4 months. Local authorities required an average of 2 months with a maximum of 3 months for effective control. Therefore, a dengue early warning given at least 3 months ahead of time would provide sufficient time for local authorities to moderate an outbreak.
Anaplastic cortical ependymomas are rare lesions with few cases reported in the literature.
We present a unique case of an anaplastic cortical ependymoma in a 51-year-old female presenting as a butterfly lesion with involvement of both frontal lobes. The patient underwent gross total resection of her tumor with further adjuvant treatment. We present the findings in our case and review the literature surrounding supratentorial ependymomas and their treatment outcomes.
Rarely, cortical ependymoma can present as a butterfly lesion and should be considered in the differential diagnosis of such lesions in adults.
Adult; Anaplastic; Cortical; Ependymoma; Supratentorial
Phosphorylation of STAT3 (signal transducer and activator of transcription 3) is critical for its nuclear import and transcriptional activity. Although a shorter STAT3β spliceform was initially described as a negative regulator of STAT3α, gene knockout studies have revealed that both forms play critical roles. We have expressed STAT3α and STAT3β at comparable levels to facilitate a direct comparison of their functional effects, and have shown their different cytokine-stimulated kinetics of phosphorylation and nuclear translocation. Notably, the sustained nuclear translocation and phosphorylation of STAT3β following cytokine exposure contrasted with a transient nuclear translocation and phosphorylation of STAT3α. Importantly, co-expression of the spliceforms revealed that STAT3β enhanced and prolonged the phosphorylation and nuclear retention of STAT3α, but a STAT3β R609L mutant, with a disrupted SH2 (Src homology 2) domain, was not tyrosine phosphorylated following cytokine stimulation and could not cross-regulate STAT3α. The physiological importance of prolonged phosphorylation and nuclear retention was indicated by transcriptome profiling of STAT3−/− cells expressing either STAT3α or STAT3β, revealing the complexity of genes that are up- and down-regulated by the STAT3 spliceforms, including a distinct set of STAT3β-specific genes regulated under basal conditions and after cytokine stimulation. These results highlight STAT3β as a significant transcriptional regulator in its own right, with additional actions to cross-regulate STAT3α phosphorylation and nuclear retention after cytokine stimulation.
cytokine; interleukin-6 (IL-6); nucleocytoplasmic trafficking; signal transducer and activator of transcription 3 (STAT3); transcription factor; transcriptome analysis; CLSM, confocal laser-scanning microscopy; DAPI, 4′,6-diamidino-2-phenylindole; DMEM, Dulbecco's modified Eagle's medium; ERt, substrate-binding portion of the oestrogen receptor; Fc, cytoplasmic fluorescence; FBS, fetal bovine serum; Fn, nuclear fluorescence; Fn/Fc, ratio of nuclear to cytoplasmic fluorescence; GO, gene ontology; gp130, glycoprotein 130; HEK, human embryonic kidney; Hsp90, heat-shock protein of 90 kDa; 4-HT, 4-hydroxytamoxifen; IL, interleukin; iSTAT3, inducible specific STAT3 spliceform; JAK, Janus kinase; MAPK, mitogen-activated protein kinase; MEF, murine embryonic fibroblast; OSM, oncostatin M; SH2, Src homology 2; SHP, SH2 domain-containing protein tyrosine phosphatase; STAT3, signal transducer and activator of transcription 3; VP16, viral protein 16; WT, wild-type
Epithelial ovarian cancer is the leading cause of death among gynaecologic cancers in Western countries. Our studies have shown that casein kinase I-epsilon (CKIε), a Wnt pathway protein, is significantly overexpressed in ovarian cancer tissues and is associated with poor survival. Ectopic expression of CKIε in normal human ovarian surface epithelial cells and inhibition of CKIε in ovarian cancer cells and in xenografts demonstrated the importance of CKIε in regulating cell proliferation and migration. Interestingly, CKIε function did not seem to involve β-catenin activity. Instead, CKIε was found to interact with several mitochondrial proteins including adenine nucleotide translocase 2 (ANT2). Inhibition of CKIε in ovarian cancer cells resulted in suppression of ANT2, downregulation of cellular ATP and the resulting cancer cells were more susceptible to chemotherapy. Our studies indicate that, in the context of ovarian cancer, the interaction between CKIε and ANT2 mediates pathogenic signalling that is distinct from the canonical Wnt/β-catenin pathway and is essential for cell proliferation and is clinically associated with poor survival.
casein kinase I epsilon; mitochondria; ovarian cancer; therapeutic target; Wnt signalling
There has been an immense interest in embryonic stem cells owing to their pluripotent property, which refers to the ability to differentiate into all cell types of an embryo. In the maintenance of this pluripotent nature, transcription factors play essential roles, and signalling pathways also act to sustain the undifferentiated state. Recent studies have unravelled multiple forms of interconnection and crosstalk between these two regulatory aspects of pluripotency. With the discovery of epiblast stem cells, there is an emerging concept that different pluripotent states could exist, and knowledge of both transcriptional networks and signalling pathways has been vital in dissecting the properties of these different states. Similar to classical reprogramming methodologies, various combinations of transcription factor transduction and the modulation of intracellular signalling have enabled the interconversion between pluripotent states. These studies provide an insight into the defining characteristics as well as the plasticity of pluripotent cells.
pluripotency; embryonic stem cell; transcriptional network; signalling pathways; mouse embryonic stem cell-like interconversion
Visceral adipose tissue (VAT) is an independent risk factor in cardiometabolic diseases and is commonly measured by computed tomography (CT). It is measured clinically by waist circumference (WC). The L4/5 intervertebral space VAT (L4/5 VAT) is traditionally used to represent total VAT volume. We set out to determine (1) the level of intervertebral space on CT that best approximates the total VAT volume; (2) compare the association between WC and VAT in Singaporean Chinese and Indian; and (3) examine the correlation between VAT and cardiometabolic risk factors.
A total of 60 Chinese and 60 Asian Indian men older than 60 years were recruited. Their medical history was taken and anthropometry was measured. Fasting glucose, insulin, lipids, adipokines and inflammatory markers were measured. Insulin resistance was evaluated by homeostasis model assessment-insulin resistance. VAT was determined by CT. Total VAT volume was calculated in 22 patients from VAT areas at seven intervertebral levels. The optimal VAT area most representative of total VAT volume was determined and used for all patients to approximate total VAT volume.
The VAT area at L2/3 intervertebral space (L2/3 VAT) correlated almost perfectly with VAT volume (R2=0.974 and 0.946 for Chinese and Indians, respectively). Subjects from the two races had similar height, weight, body mass index (BMI), WC and L2/3 VAT but more Indian men had hypertension, hyperlipidemia and type 2 diabetes mellitus. WC was correlated with the L2/3 VAT area in both Chinese (r=0.484, P<0.001) and Indian subjects (r=0.366, P=0.004) without racial difference (P=0.2 for interaction term). L2/3 VAT also correlated better with cardiometabolic risk factors, adipokines and C-reactive protein than WC, BMI or L4/5 VAT.
The L2-L3 intervertebral space was the best anatomic level for a single-slice CT cross-sectional area measurement of VAT to approximate total body visceral adipose volume in this population of Chinese and Asian Indian men older than 60 years. L2/3 VAT was better correlated with multiple cardiovascular risk factors, adipokines and inflammatory marker than either L4/5 VAT, WC or BMI.
visceral adipose tissue; waist circumference; metabolic syndrome; Chinese; Asian Indian; Singapore
Aldehyde dehydrogenases belong to a superfamily of detoxifying enzymes that protect cells from carcinogenic aldehydes. Of the superfamily, ALDH1A1 has gained most attention because current studies have shown that its expression is associated with human cancer stem cells. However, ALDH1A1 is only one of the 19 human ALDH subfamilies currently known. The purpose of the present study was to determine if the expression and activities of other major ALDH isozymes are associated with human ovarian cancer and ovarian cancer sphere cultures.
Immunohistochemistry was used to delineate ALDH isozyme localization in clinical ovarian tissues. Western Blot analyses were performed on lysates prepared from cancer cell lines and ovarian cancer spheres to confirm the immunohistochemistry findings. Quantitative reverse transcription-polymerase chain reactions were used to measure the mRNA expression levels. The Aldefluor® assay was used to measure ALDH activity in cancer cells from the four tumor subtypes.
Immunohistochemical staining showed significant overexpression of ALDH1A3, ALDH3A2, and ALDH7A1 isozymes in ovarian tumors relative to normal ovarian tissues. The expression and activity of ALDH1A1 is tumor type-dependent, as seen from immunohistochemisty, Western blot analysis, and the Aldefluor® assay. The expression was elevated in the mucinous and endometrioid ovarian epithelial tumors than in serous and clear cell tumors. In some serous and most clear cell tumors, ALDH1A1 expression was found in the stromal fibroblasts. RNA expression of all studied ALDH isozymes also showed higher expression in endometrioid and mucinous tumors than in the serous and clear cell subtypes. The expression of ALDH enzymes showed tumor type-dependent induction in ovarian cancer cells growing as sphere suspensions in serum-free medium.
The results of our study indicate that ALDH enzyme expression and activity may be associated with specific cell types in ovarian tumor tissues and vary according to cell states. Elucidating the function of the ALDH isozymes in lineage differentiation and pathogenesis may have significant implications for ovarian cancer pathophysiology.
Aldehyde dehydrogenase; Isozymes; Ovarian tumors; Sphere cultures; Tumor-type specific expression