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107 result(s) for "Sim, X."
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Adverse effects following anti–COVID-19 vaccination with mRNA-based BNT162b2 are alleviated by altering the route of administration and correlate with baseline enrichment of T and NK cell genes
Ensuring high vaccination and even booster vaccination coverage is critical in preventing severe Coronavirus Disease 2019 (COVID-19). Among the various COVID-19 vaccines currently in use, the mRNA vaccines have shown remarkable effectiveness. However, systemic adverse events (AEs), such as postvaccination fatigue, are prevalent following mRNA vaccination, and the underpinnings of which are not understood. Herein, we found that higher baseline expression of genes related to T and NK cell exhaustion and suppression were positively correlated with the development of moderately severe fatigue after Pfizer-BioNTech BNT162b2 vaccination; increased expression of genes associated with T and NK cell exhaustion and suppression reacted to vaccination were associated with greater levels of innate immune activation at 1 day postvaccination. We further found, in a mouse model, that altering the route of vaccination from intramuscular (i.m.) to subcutaneous (s.c.) could lessen the pro-inflammatory response and correspondingly the extent of systemic AEs; the humoral immune response to BNT162b2 vaccination was not compromised. Instead, it is possible that the s.c. route could improve cytotoxic CD8 T-cell responses to BNT162b2 vaccination. Our findings thus provide a glimpse of the molecular basis of postvaccination fatigue from mRNA vaccination and suggest a readily translatable solution to minimize systemic AEs.
A phase I/II randomized, double-blinded, placebo-controlled trial of a self-amplifying Covid-19 mRNA vaccine
Coronavirus disease-19 (Covid-19) pandemic have demonstrated the importantance of vaccines in disease prevention. Self-amplifying mRNA vaccines could be another option for disease prevention if demonstrated to be safe and immunogenic. Phase 1 of this randomized, double-blinded, placebo-controlled trial ( N  = 42) assessed the safety, tolerability, and immunogenicity in healthy young and older adults of ascending levels of one-dose ARCT-021, a self-amplifying mRNA vaccine against Covid-19. Phase 2 ( N  = 64) tested two-doses of ARCT-021 given 28 days apart. During phase 1, ARCT-021 was well tolerated up to one 7.5 μg dose and two 5.0 μg doses. Local solicited AEs, namely injection-site pain and tenderness were more common in ARCT-021vaccinated, while systemic solicited AEs, mainly fatigue, headache and myalgia were reported in 62.8% and 46.4% of ARCT-021 and placebo recipients, respectively. Seroconversion rate for anti-S IgG was 100% in all cohorts, except for the 1 μg one-dose in younger adults and the 7.5 μg one-dose in older adults. Anti-S IgG and neutralizing antibody titers showed a general increase with increasing dose, and overlapped with titers in Covid-19 convalescent patients. T-cell responses were also observed in response to stimulation with S-protein peptides. Taken collectively, ARCT-021 is immunogenic and has favorable safety profile for further development.
Cost-savings of short stay sleeve gastrectomy and walk-in hydration clinic versus conventional inpatient care
ObjectiveWe aim to evaluate the cost-saving of the short stay ward (SSW) versus conventional inpatient care following sleeve gastrectomy (LSG). We also compared the readmission rates pre- and post-inception of the intravenous hydration clinic and analyzed the cost-savings.MethodsPatients who underwent LSG between December 2021 to March 2022 with SSW care were compared with standard inpatient care. Total costs were analyzed using univariate analysis. With a separate cohort of patients, 30-day readmission rates in the 12-months preceding and following implementation of the IV hydration clinic and associated cost-savings were evaluated.ResultsAfter matching on the propensity score to within ± 0.1, 20-subjects pairs were retained. The total cost per SSW-subject was significantly lower at $13,647.81 compared to $15,565.27 for conventional inpatient care (p = 0.0302). Lower average ward charges ($667.76 vs $1371.34, p < 0.0001), lower average daily treatment fee per case ($235.68 vs $836.54, p < 0.0001), and lower average laboratory investigation fee ($612.31 vs $797.21, p < 0.0001) accounted for the difference in costs between the groups. Thirty-day readmission rate reduced from 8.9 to 1.8% after implementation of the hydration clinic (p < 0.01) with decreased 30-day readmission cost (S$96,955.57 vs. S$5910.27, p < 0.01).ConclusionSSW for LSG is cost-effective and should be preferred to inpatient management. Walk-in hydration clinics significantly reduced readmission rates and result in tremendous cost-savings.
Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park
Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management.
Replication of 13 obesity loci among Singaporean Chinese, Malay and Asian-Indian populations
Objective: Recent genome-wide association studies (GWAS) have identified 38 obesity-associated loci among European populations. However, their contribution to obesity in other ethnicities is largely unknown. Methods: We utilised five GWAS ( N =10 482) from Chinese (three cohorts, including one with type 2 diabetes and another one of children), Malay and Indian ethnic groups from Singapore. Data sets were analysed individually and subsequently in combined meta-analysis for Z-score body-mass index (BMI) associations. Results: Variants at the FTO locus showed the strongest associations with BMI Z-score after meta-analysis ( P -values 1.16 × 10 −7 –7.95 × 10 −7 ). We further detected associations with nine other index obesity variants close to the MC4R , GNPDA2 , TMEM18 , QPCTL / GIPR , BDNF , ETV5 , MAP2K5 / SKOR1 , SEC16B and TNKS / MSRA loci (meta-analysis P -values ranging from 3.58 × 10 −4 –1.44 × 10 −2 ). Three other single-nucleotide polymorphisms (SNPs) from CADM2 , PTBP2 and FAIM2 were associated with BMI ( P -value ⩽0.0418) in at least one dataset. The neurotrophin/TRK pathway ( P -value=0.029) was highlighted by pathway-based analysis of loci that had statistically significant associations among Singaporean populations. Conclusion: Our data confirm the role of FTO in obesity predisposition among Chinese, Malays and Indians, the three major Asian ethnic groups. We additionally detected associations for 12 obesity-associated SNPs among Singaporeans. Thus, it is likely that Europeans and Asians share some of the genetic predisposition to obesity. Furthermore, the neurotrophin/TRK signalling may have a central role for common obesity among Asians.
Proteasome Inhibition Promotes Parkin-Ubc13 Interaction and Lysine 63-Linked Ubiquitination
Disruption of the ubiquitin-proteasome system, which normally identifies and degrades unwanted intracellular proteins, is thought to underlie neurodegeneration. Supporting this, mutations of Parkin, a ubiquitin ligase, are associated with autosomal recessive parkinsonism. Remarkably, Parkin can protect neurons against a wide spectrum of stress, including those that promote proteasome dysfunction. Although the mechanism underlying the preservation of proteasome function by Parkin is hitherto unclear, we have previously proposed that Parkin-mediated K63-linked ubiquitination (which is usually uncoupled from the proteasome) may serve to mitigate proteasomal stress by diverting the substrate load away from the machinery. By means of linkage-specific antibodies, we demonstrated here that proteasome inhibition indeed promotes K63-linked ubiquitination of proteins especially in Parkin-expressing cells. Importantly, we further demonstrated that the recruitment of Ubc13 (an E2 that mediates K63-linked polyubiquitin chain formation exclusively) by Parkin is selectively enhanced under conditions of proteasomal stress, thus identifying a mechanism by which Parkin could promote K63-linked ubiquitin modification in cells undergoing proteolytic stress. This mode of ubiquitination appears to facilitate the subsequent clearance of Parkin substrates via autophagy. Consistent with the proposed protective role of K63-linked ubiquitination in times of proteolytic stress, we found that Ubc13-deficient cells are significantly more susceptible to cell death induced by proteasome inhibitors compared to their wild type counterparts. Taken together, our study suggests a role for Parkin-mediated K63 ubiquitination in maintaining cellular protein homeostasis, especially during periods when the proteasome is burdened or impaired.
Genome-wide association study in a Chinese population identifies a susceptibility locus for type 2 diabetes at 7q32 near PAX4
Aims/hypothesis 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. Methods 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. Results 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 ( p meta  = 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 ( p meta  = 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. Conclusions/interpretation 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.
Rapid measurement of SARS-CoV-2 spike T cells in whole blood from vaccinated and naturally infected individuals
Defining the correlates of protection necessary to manage the COVID-19 pandemic requires the analysis of both antibody and T cell parameters, but the complexity of traditional tests limits virus-specific T cell measurements. We tested the sensitivity and performance of a simple and rapid SARS-CoV-2 spike protein-specific T cell test based on the stimulation of whole blood with peptides covering the SARS-CoV-2 spike protein, followed by cytokine (IFN-γ, IL-2) measurement in different cohorts including BNT162b2-vaccinated individuals (n = 112), convalescent asymptomatic and symptomatic COVID-19 patients (n = 130), and SARS-CoV-1-convalescent individuals (n = 12). The sensitivity of this rapid test is comparable to that of traditional methods of T cell analysis (ELISPOT, activation-induced marker). Using this test, we observed a similar mean magnitude of T cell responses between the vaccinees and SARS-CoV-2 convalescents 3 months after vaccination or virus priming. However, a wide heterogeneity of the magnitude of spike-specific T cell responses characterized the individual responses, irrespective of the time of analysis. The magnitude of these spike-specific T cell responses cannot be predicted from the neutralizing antibody levels. Hence, both humoral and cellular spike-specific immunity should be tested after vaccination to define the correlates of protection necessary to evaluate current vaccine strategies.
Immune gene expression analysis indicates the potential of a self-amplifying Covid-19 mRNA vaccine
Remarkable potency has been demonstrated for mRNA vaccines in reducing the global burden of the ongoing COVID-19 pandemic. An alternative form of the mRNA vaccine is the self-amplifying mRNA (sa-mRNA) vaccine, which encodes an alphavirus replicase that self-amplifies the full-length mRNA and SARS-CoV-2 spike (S) transgene. However, early-phase clinical trials of sa-mRNA COVID-19 vaccine candidates have questioned the potential of this platform to develop potent vaccines. We examined the immune gene response to a candidate sa-mRNA vaccine against COVID-19, ARCT-021, and compared our findings to the host response to other forms of vaccines. In blood samples from healthy volunteers that participated in a phase I/II clinical trial, greater induction of transcripts involved in Toll-like receptor (TLR) signalling, antigen presentation and complement activation at 1 day post-vaccination was associated with higher anti-S antibody titers. Conversely, transcripts involved in T-cell maturation at day 7 post-vaccination informed the magnitude of eventual S-specific T-cell responses. The transcriptomic signature for ARCT-021 vaccination strongly correlated with live viral vector vaccines, adjuvanted vaccines and BNT162b2 1 day post-vaccination. Moreover, the ARCT-021 signature correlated with day 7 YF17D live-attenuated vaccine transcriptomic responses. Altogether, our findings show that sa-mRNA vaccination induces innate immune responses that are associated with the development of adaptive immunity from other forms of vaccines, supporting further development of this vaccine platform for clinical application.
Prediction model to identify infectious COVID-19 patients in the emergency department
Real-time reverse-transcriptase polymerase chain reaction (RT-PCR) has been the gold standard for diagnosing coronavirus disease 2019 (COVID-19) but has a lag time for the results. An effective prediction algorithm for infectious COVID-19, utilized at the emergency department (ED), may reduce the risk of healthcare-associated COVID-19. To develop a prototypic prediction model for infectious COVID-19 at the time of presentation to the ED. Retrospective cohort study of all adult patients admitted to Singapore General Hospital (SGH) through ED between March 15, 2020, and December 31, 2022, with admission of COVID-19 RT-PCR results. Two prediction models were developed and evaluated using area under the curve (AUC) of receiver operating characteristics (ROC) to identify infectious COVID-19 patients (cycle threshold (Ct) of <25). Total of 78,687 patients were admitted to SGH through ED during study period. 6,132 of them tested severe acute respiratory coronavirus 2 positive on RT-PCR. Nearly 70% (4,226 of 6,132) of the patients had infectious COVID-19 (Ct<25). Model that included demographics, clinical history, symptom and laboratory variables had AUROC of 0.85 with sensitivity and specificity of 80.0% & 72.1% respectively. When antigen rapid test results at ED were available and added to the model for a subset of the study population, AUROC reached 0.97 with sensitivity and specificity of 95.0% and 92.8% respectively. Both models maintained respective sensitivity and specificity results when applied to validation data. Clinical predictive models based on available information at ED can be utilized for identification of infectious COVID-19 patients and may enhance infection prevention efforts.