Publications by authors named "Alex Cheong"

The skin and its microbiome function to protect the host from pathogen colonization and environmental stressors. In this study, using the Wisconsin Miniature Swine™ model, we characterize the porcine skin fungal and bacterial microbiomes, identify bacterial isolates displaying antifungal activity, and use whole-genome sequencing to identify biosynthetic gene clusters encoding for secondary metabolites that may be responsible for the antagonistic effects on fungi. Through this comprehensive approach of paired microbiome sequencing with culturomics, we report the discovery of novel species of Corynebacterium and Rothia.

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Objective: Persistent hydrocephalus following posterior fossa brain tumor (PFBT) resection is a common cause of morbidity in pediatric brain tumor patients, for which the optimal treatment is debated. The purpose of this study was to compare treatment outcomes between VPS and ETV in patients with persistent hydrocephalus following surgical resection of a PFBT.

Methods: A post-hoc analysis was performed of the Hydrocephalus Clinical Research Network (HCRN) prospective observational study evaluating VPS and ETV for pediatric patients.

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Introduction: Obstructive sleep apnoea (OSA) has been thought to be associated with glaucoma, however there are many conflicting studies on this topic. With many new studies having been published since the previous meta-analysis, we believe it is important to clarify this association. Hence, in this study we meta-analyse the recent literature regarding the association between OSA and glaucoma.

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Ageing research focuses on identifying lifespan modifiers and understanding and appropriately interpreting their effects. One of the most relevant quantities being studied is the shape of the survival curve that can reveal crucial information on the mechanism of action. Here, we introduce a bilogistic model to describe the shape of the lifespan curves of populations.

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Purpose: Observational studies suggest that myopic eyes carry a greater risk of primary open-angle glaucoma (POAG); however, the evidence for this association is inconsistent. This may be the result of confounding factors that arise from myopia that complicate clinical tests for glaucoma. This study used Mendelian randomization (MR) analysis to determine genetic causal associations among myopia, glaucoma, and glaucoma-related traits that overcome the effects of external confounders.

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Article Synopsis
  • Obstructive sleep apnoea (OSA) is suspected to be linked to floppy eyelid syndrome (FES), but previous research has produced inconclusive results regarding this association.
  • This study systematically reviewed data from four medical databases and conducted a meta-analysis on observational studies to determine the relationship between OSA and FES, finding that more severe OSA significantly increases the risk of developing FES.
  • The analysis concluded that severe OSA correlates with the highest risk of FES, and further longitudinal studies are necessary for a more definitive understanding of this relationship.
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Article Synopsis
  • * A thorough search of clinical trial databases revealed 111 studies with over 103,000 patients, focusing on differences in outcomes for type 1 and type 2 diabetes.
  • * Results indicated that while SGLT1/2 inhibitors reduced the risk of heart attack and stroke in type 2 diabetes patients, SGLT2 inhibitors were more effective at lowering HbA1c levels; however, SGLT1/2 inhibitors had a higher risk of
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Introduction: Sodium-glucose cotransporter 2 (SGLT2) inhibitors are increasingly utilized in the treatment of diabetes mellitus as well as therapeutic extra-glycemic effects. However, there are still concerns over complications such as amputation events, given the results from the Canagliflozin Cardiovascular Assessment Study (CANVAS) trial. Hence, we conducted a systematic review and meta-analysis of randomized-controlled trials to investigate the effect of SGLT2 inhibitors on amputation events.

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Article Synopsis
  • A meta-analysis was conducted to evaluate the weight loss effects of SGLT2 inhibitors and the combined SGLT1/SGLT2 inhibitors, using data from various trials published over two decades.
  • The analysis included 116 randomized-controlled trials with nearly 100,000 patients, revealing an average weight loss of -1.79 kg and a BMI change of -0.71 kg/m compared to placebo.
  • The study found that SGLT1/SGLT2 inhibitors were more effective for weight reduction than SGLT2 inhibitors alone, highlighting their potential in weight management, though more research is needed.
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Background And Objective: In recent trials, sodium-glucose cotransporter 2 (SGLT2) inhibitors proved effective as treatment for heart failure. However, the relative efficacy of sacubitril/valsartan against SGLT2 inhibitor in patients with heart failure remains unknown. Hence, we performed a network meta-analysis to compare the effects of sacubitril/valsartan against SGLT2 inhibitors on cardiovascular outcomes in patients with heart failure.

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In 2020, lung cancer was the leading cause of cancer deaths and the most common cancer in men. Although obstructive sleep apnea (OSA) has been postulated to be carcinogenic, epidemiological studies are inconclusive. To investigate the associations between OSA and the incidence and mortality of lung cancer.

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Objectives: Recent clinical trials have shown the potential of sodium glucose cotransporter (SGLT) 2 inhibitors to reduce the risk of atrial fibrillation but not stroke. We conducted a systematic review and meta-analysis to clarify if SGLT2 or combined SGLT1/2 inhibitors affect the risk of atrial fibrillation and stroke in patients regardless of diabetic status.

Materials And Methods: Four electronic databases were searched on 21st November 2020 for studies evaluating outcomes of stroke and atrial fibrillation with SGLT2 or combined SGLT1/2 inhibitors in both diabetic and non-diabetic patients.

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Here we describe a simple method based on secreted luciferase driven by a hypoxia-inducible factor (HIF) response element (HRE) that allows the acquisition of dynamic and high-throughput data on HIF transcriptional activity during hypoxia and pharmacological activation of HIF. The sensitivity of the assay allows for the secreted luciferase to be consecutively sampled (as little as 1% of the total supernatant) over an extended time period, thus allowing the acquisition of time-resolved HIF transcriptional activity.

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A sufficient supply molecular oxygen is essential for the maintenance of physiologic metabolism and bioenergetic homeostasis for most metazoans. For this reason, mechanisms have evolved for eukaryotic cells to adapt to conditions where oxygen demand exceeds supply (hypoxia). These mechanisms rely on the modification of pre-existing proteins, translational arrest and transcriptional changes.

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Fibrosis is a complication of chronic inflammatory disorders such as inflammatory bowel disease, a condition which has limited therapeutic options and often requires surgical intervention. Pharmacologic inhibition of oxygen-sensing prolyl hydroxylases, which confer oxygen sensitivity upon the hypoxia-inducible factor pathway, has recently been shown to have therapeutic potential in colitis, although the mechanisms involved remain unclear. Here, we investigated the impact of hydroxylase inhibition on inflammation-driven fibrosis in a murine colitis model.

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Cellular exposure to hypoxia results in altered gene expression in a range of physiologic and pathophysiologic states. Discrete cohorts of genes can be either up- or down-regulated in response to hypoxia. While the Hypoxia-Inducible Factor (HIF) is the primary driver of hypoxia-induced adaptive gene expression, less is known about the signalling mechanisms regulating hypoxia-dependent gene repression.

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Signal integration determines cell fate on the cellular level, affects cognitive processes and affective responses on the behavioural level, and is likely to be involved in psychoneurobiological processes underlying mood disorders. Interactions between stimuli may subjected to time effects. Time-dependencies of interactions between stimuli typically lead to complex cell responses and complex responses on the behavioural level.

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The hypoxia-inducible factor (HIF) is a key regulator of the cellular response to hypoxia which promotes oxygen delivery and metabolic adaptation to oxygen deprivation. However, the degree and duration of HIF-1α expression in hypoxia must be carefully balanced within cells in order to avoid unwanted side effects associated with excessive activity. The expression of HIF-1α mRNA is suppressed in prolonged hypoxia, suggesting that the control of HIF1A gene transcription is tightly regulated by negative feedback mechanisms.

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Cyclooxygenase 2 (COX2), a key regulatory enzyme of the prostaglandin/eicosanoid pathway, is an important target for anti-inflammatory therapy. It is highly induced by pro-inflammatory cytokines in a Nuclear factor kappa B (NFκB)-dependent manner. However, the mechanisms determining the amplitude and dynamics of this important pro-inflammatory event are poorly understood.

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We show theoretically and experimentally a mechanism behind the emergence of wide or bimodal protein distributions in biochemical networks with nonlinear input-output characteristics (the dose-response curve) and variability in protein abundance. Large cell-to-cell variation in the nonlinear dose-response characteristics can be beneficial to facilitate two distinct groups of response levels as opposed to a graded response. Under the circumstances that we quantify mathematically, the two distinct responses can coexist within a cellular population, leading to the emergence of a bimodal protein distribution.

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Genetic experiments over the last few decades have identified many regulatory proteins critical for DNA transcription. The dynamics of their transcriptional activities shape the differential expression of the genes they control. Here we describe a simple method, based on the secreted luciferase, to measure the activities of two transcription factors NFκB and HIF.

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Hypoxia is a prominent feature of chronically inflamed tissues. Oxygen-sensing hydroxylases control transcriptional adaptation to hypoxia through the regulation of hypoxia-inducible factor (HIF) and nuclear factor κB (NF-κB), both of which can regulate the inflammatory response. Furthermore, pharmacologic hydroxylase inhibitors reduce inflammation in multiple animal models.

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Oxygen is a crucial molecule for cellular function. When oxygen demand exceeds supply, the oxygen sensing pathway centred on the hypoxia inducible factor (HIF) is switched on and promotes adaptation to hypoxia by up-regulating genes involved in angiogenesis, erythropoiesis and glycolysis. The regulation of HIF is tightly modulated through intricate regulatory mechanisms.

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