Publications by authors named "Sung Chun"

Parkinson's disease (PD) is a neurodegenerative disorder caused by the degeneration of dopaminergic neurons in the brain stem. PD is mostly sporadic, but familial PD (FPD) cases are recorded in different studies. The first gene mutation that is linked to FPD is α-synuclein (α-syn).

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Diet is a robust entrainment cue that regulates diurnal rhythms of the gut microbiome. We and others have shown that disruption of the circadian clock drives the progression of colorectal cancer (CRC). While certain bacterial species have been suggested to play driver roles in CRC, it is unknown whether the intestinal clock impinges on the microbiome to accelerate CRC pathogenesis.

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Article Synopsis
  • - The circadian clock plays a crucial role in regulating the immune system and is important for both disease defense and cancer detection.
  • - Research using single-cell RNA sequencing reveals that certain immune cells, particularly PD-L1-expressing myeloid-derived suppressor cells (MDSCs), oscillate in numbers based on the time of day and suppress the activity of CD8 T cells.
  • - Timing the administration of anti-PD-L1 treatment to coincide with the peak levels of MDSCs enhances its effectiveness, highlighting the importance of circadian rhythms in cancer immunotherapy.
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  • Autoimmune and inflammatory diseases involve multiple genes and often share risk alleles, making it tough to pinpoint specific causes.
  • A study analyzing over 129,000 cases and controls found that about 40% of related genetic associations come from the same genetic variants across six different diseases.
  • By improving the resolution of genetic mapping, the researchers could identify more related gene expressions, suggesting that while there are common mechanisms between these diseases, there isn't just one universal cause for all autoimmune diseases.
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Parkinson's disease (PD) is a common neurodegenerative disorder that is affecting an increasing number of older adults. Although PD is mostly sporadic, genetic mutations have been found in cohorts of families with a history of familial PD (FPD). The first such mutation linked to FPD causes a point mutation (A53T) in α-synuclein (α-syn), a major component of Lewy bodies, which are a classical pathological hallmark of PD.

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Rationale: Respiratory virus-induced inflammation is the leading cause of asthma exacerbation, frequently accompanied by induction of interferon-stimulated genes (). How asthma-susceptibility genes modulate cellular response upon viral infection by fine-tuning induction and subsequent airway inflammation in genetically susceptible asthma patients remains largely unknown.

Objectives: To decipher the functions of gasdermin B (encoded by ) in respiratory virus-induced lung inflammation.

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Backgruound: This study investigated the real-world efficacy and safety of insulin degludec/insulin aspart (IDegAsp) in Korean adults with type 2 diabetes mellitus (T2DM), whose insulin treatment was switched to IDegAsp.

Methods: This was a multicenter, retrospective, observational study comprising two 26-week treatment periods, before and after switching to IDegAsp, respectively. Korean adults with uncontrolled T2DM treated with basal or premix insulin (±oral antidiabetic drugs) were enrolled.

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  • The study explores the link between gut microbiota and rheumatoid arthritis (RA), aiming to identify specific microbial species associated with RA through serum analysis.
  • Researchers assessed antibody levels against various intestinal microbes in RA patients compared to healthy individuals, discovering significant differences in immune responses.
  • The findings indicate that certain microbes have therapeutic potential by reducing inflammation and restoring gut health, suggesting a possible new approach for RA treatment.
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Interstitial lung disease (ILD) involves persistent inflammation and fibrosis, leading to respiratory failure and even death. Adult tissue-derived mesenchymal stem cells (MSCs) show potential in ILD therapeutics but obtaining an adequate quantity of cells for drug application is difficult. Daewoong Pharmaceutical's MSCs (DW-MSCs) derived from embryonic stem cells sustain a high proliferative capacity following long-term culture and expansion.

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  • A study compared the effectiveness and safety of low-intensity atorvastatin combined with ezetimibe against moderate-intensity atorvastatin alone in 290 patients in Korea needing cholesterol-lowering therapy.
  • The results showed that the combination therapy (atorvastatin 5 mg + ezetimibe 10 mg) significantly lowered LDL cholesterol levels (49.2% reduction) compared to the other treatment groups, particularly outperforming ezetimibe alone (18.7%).
  • Overall, the combination therapy not only improved LDL cholesterol but also led to better results in total cholesterol and triglyceride levels, indicating it's a more effective option for patients with low to intermediate cardiovascular risk.
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In addition to rare genetic variants and the locus, common genetic variants contribute to idiopathic pulmonary fibrosis (IPF) risk. The predictive power of common variants outside the locus for IPF and interstitial lung abnormalities (ILAs) is unknown. We tested the predictive value of IPF polygenic risk scores (PRSs) with and without the region on IPF, ILA, and ILA progression.

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Background: Existing module-based differential co-expression methods identify differences in gene-gene relationships across phenotype or exposure structures by testing for consistent changes in transcription abundance. Current methods only allow for assessment of co-expression variation across a singular, binary or categorical exposure or phenotype, limiting the information that can be obtained from these analyses.

Methods: Here, we propose a novel approach for detection of differential co-expression that simultaneously accommodates multiple phenotypes or exposures with binary, ordinal, or continuous data types.

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Aims: Dysregulation of adrenocortical steroid (corticosteroids) biosynthesis leads to pathological conditions such as Cushing's syndrome. Although several classes of steroid biosynthesis inhibitors have been developed to treat cortisol overproduction, limitations such as insufficient efficacy, adverse effects, and/or tolerability still remain. The present study aimed to develop a new class of small molecules that inhibit cortisol production, and investigated their putative modes of action.

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The environmental light/dark cycle has left its mark on the body's physiological functions to condition not only our inner biology, but also the interaction with external cues. In this scenario, the circadian regulation of the immune response has emerged as a critical factor in defining the host-pathogen interaction and the identification of the underlying circuitry represents a prerequisite for the development of circadian-based therapeutic strategies. The possibility to track down the circadian regulation of the immune response to a metabolic pathway would represent a unique opportunity in this direction.

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Genetic association studies of many heritable traits resulting from physiological testing often have modest sample sizes due to the cost and burden of the required phenotyping. This reduces statistical power and limits discovery of multiple genetic associations. We present a strategy to leverage pleiotropy between traits to both discover new loci and to provide mechanistic hypotheses of the underlying pathophysiology.

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Article Synopsis
  • The genetic basis of traits is mainly polygenic and influenced by non-coding alleles, which are thought to have minor regulatory roles in gene expression.
  • Despite having access to extensive gene expression and epigenomic data, few connections between genetic variants and gene activity have been established.
  • A study identified 220 gene-trait pairs influenced by protein-coding variants, revealing little evidence that typical gene expression explains associations with complex traits, indicating a need for improved models to understand these complexities.
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Metabolic rewiring is a hallmark feature prevalent in cancer cells as well as insulin resistance (IR) associated with diet-induced obesity (DIO). For instance, tumor metabolism shifts towards an enhanced glycolytic state even under aerobic conditions. In contrast, DIO triggers lipid-induced IR by impairing insulin signaling and reducing insulin-stimulated glucose uptake.

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Background: Asthma is a heterogeneous common respiratory disease that remains poorly understood. The established genetic associations fail to explain the high estimated heritability, and the prevalence of asthma differs between populations and geographic regions. Robust association analyses incorporating different genetic ancestries and whole-genome sequencing data may identify novel genetic associations.

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An alarming rise in young onset colorectal cancer (CRC) has been reported; however, the underlying molecular mechanism remains undefined. Suspected risk factors of young onset CRC include environmental aspects, such as lifestyle and dietary factors, which are known to affect the circadian clock. We find that both genetic disruption and environmental disruption of the circadian clock accelerate driven CRC pathogenesis in vivo.

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Isolation of primary hepatocytes and culturing these cells ex vivo provides a powerful platform to model liver physiology in vivo. Primary hepatocytes can be cultured for several days, the circadian clock can be synchronized, and these primary cells can be utilized for functional gene regulation analysis and metabolic studies. In this chapter, we describe detailed methodology for isolation of viable primary hepatocytes, techniques for culturing these cells, methods for synchronization of the circadian clock, transfection and luciferase reporter analysis, as well as glucose production assays as a functional readout of metabolic state.

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Background: The choice of an optimal oral hypoglycemic agent in the initial treatment periods for type 2 diabetes mellitus (T2DM) patients remains difficult and deliberate. We compared the efficacy and safety of glimepiride (GLIM), alogliptin (ALO), and alogliptin-pioglitazone (ALO-PIO) in poorly controlled T2DM patients with drug-naïve or metformin failure.

Methods: In this three-arm, multicenter, open-label, randomized, controlled trial, poorly controlled T2DM patients were randomized to receive GLIM (n=35), ALO (n=31), or ALO-PIO (n=33) therapy for 24 weeks.

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Background: Thiazolidinediones (TZDs) have been associated with various safety concerns including weight gain, bladder cancer, and congestive heart failure (CHF). This study evaluated the efficacy and safety of lobeglitazone, a novel TZD in patients with type 2 diabetes mellitus (T2DM) in real practice.

Methods: In this non-interventional, multi-center, retrospective, and observational study conducted at 15 tertiary or secondary referral hospitals in Korea, a total of 2,228 patients with T2DM who received lobeglitazone 0.

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The aim of this study was to investigate the impact of the coronavirus disease 2019 (COVID-19) pandemic on the continuity of care (COC) for patients with hypertension. Additionally, the factor of whether participants were treated via telemedicine was also considered. This study used the National Health Insurance and Medical Aid claims data of the Republic of Korea between 2019 and 2020.

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