Publications by authors named "Hyunjun Ahn"

Purpose: Although both cerebral venous thrombosis (CVT) and ischemic stroke involve cerebrovascular flow disruption, they differ in pathophysiology, clinical features, and outcomes. This study compared patient-reported outcomes (PROs) and their trajectories over time between CVT and ischemic stroke patients.

Methods: This retrospective cohort study included patients hospitalized for CVT or ischemic stroke who completed at least one of the following PRO in cerebrovascular clinic between January 2019 and April 2024: Patient Health Questionnaire-9, PROMIS Global Health, Neuro-QoL cognitive function, and PROMIS scales for pain interference, physical function, social role satisfaction, fatigue, self-efficacy and sleep disturbance.

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Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) enters the host cell by binding to angiotensin-converting enzyme 2 (ACE2). While evolutionarily conserved, ACE2 receptors differ across various species and differential interactions with Spike (S) glycoproteins of SARS-CoV-2 viruses impact species specificity. Reverse zoonoses led to SARS-CoV-2 outbreaks on multiple American mink (Mustela vison) farms during the pandemic and gave rise to mink-associated S substitutions known for transmissibility between mink and zoonotic transmission to humans.

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Background: Bell's palsy is an idiopathic facial palsy with an unknown cause, and 75% of patients heal spontaneously. However, the other 25% of patients continue experiencing mild or severe disabilities, resulting in a reduced quality of life. Currently, various treatment methods have been developed to treat this disease.

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Background: Syringomyelia is a disease caused by the formation of a cavity inside the spinal cord and is accompanied by such symptoms as pain, paresthesia, and urination and defecation disorders, and in severe cases causes various paralyses. Currently, there are only surgical methods for the treatment of syringomyelia, but these methods carry the possibility of failure, recurrence, and side effects.

Case Summary: The patient was a 59-year-old woman who suffered from pain due to syringomyelia.

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Since the 1960s, rapid urbanization has caused serious deterioration in the quantity and quality of instream flows in South Korea. As demands for healthy instream ecology, landscape, and water-friendly environments have increased, the government has revised the relevant legal codes. In 2017, the environmental flow, defined as the minimum flow to conserve the health of aquatic ecosystems, has been endorsed in the Water Environment Conservation Act.

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Background: Stroke is one of the major causes of disability and death worldwide. Some treatments for stroke exist, but existing treatment methods have limitations such as difficulty in the regeneration of damaged neuronal cells of the brain. Recently, mesenchymal stem cells (MSCs) have been studied as a therapeutic alternative for stroke, and various preclinical and case studies have been reported.

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Background: Psoriasis is a chronic autoimmune disease that usually manifests as a red scaly epidermis, induration, and hyperproliferation of basal keratinocytes. About 2% of the world's population suffers from psoriasis but there are no clear therapeutics yet. Recently, mesenchymal stem cells (MSCs) have been regarded as a therapeutic alternative for autoimmune diseases, as they possess immunosuppressive effects without risks.

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The transcription master regulator MYC plays an essential role in regulating major cellular programs and is a well-established therapeutic target in cancer. However, MYC targeting for drug discovery is challenging. New therapeutic approaches to control MYC-dependent malignancy are urgently needed.

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Background: Alopecia areata (AA) is a common autoimmune disease characterized by hair loss. AA appears in extensive forms, such as progressive and diffusing hair loss (diffuse AA), a total loss of scalp hair (alopecia totalis), and complete loss of hair over the entire body (alopecia universalis). Recently, mesenchymal stem cells (MSCs) have been identified as a therapeutic alternative for autoimmune diseases.

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The M2-1 protein of human respiratory syncytial virus (HRSV) is a transcription anti-terminator that regulates the processivity of the HRSV RNA-dependent RNA polymerase (RdRP). Here, we report a crystal structure of HRSV M2-1 bound to a short positive-sense gene-end RNA (SH7) at 2.7 Å resolution.

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Cohen syndrome (CS), a rare autosomal recessive disorder, has been associated with genetic mutations in the gene, which regulates vesicle-mediated protein sorting and transport. However, the cellular mechanism underlying CS pathogenesis in patient-derived human neurons remains unknown. We identified a novel compound heterozygous mutation, due to homozygous variation of biparental origin and heterozygous variation inherited from the father, in the gene in a 20-month-old female patient.

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The templates for transcription and replication by respiratory syncytial virus (RSV) polymerase are helical nucleocapsids (NCs), formed by viral RNAs that are encapsidated by the nucleoprotein (N). Proper NC assembly is vital for RSV polymerase to engage the RNA template for RNA synthesis. Previous studies of NCs or nucleocapsid-like particles (NCLPs) from RSV and other nonsegmented negative-sense RNA viruses have provided insights into the overall NC architecture.

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In Parkinson's disease (PD) research, human neuroblastoma and immortalized neural cell lines have been widely used as models. The advancement in the field of reprogramming technology has provided tools for generating patient-specific induced pluripotent stem cells (hiPSCs) as well as human induced neuronal progenitor cells (hiNPCs). These cells have revolutionized the field of disease modeling, especially in neural diseases.

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Background: To evaluate the modulation indices (MIs) for predicting the plan delivery accuracies of intensity-modulated radiation therapy (IMRT) plans.

Methods: A total of 100 dynamic IMRT plans that used TrueBeam STx and 102 dynamic IMRT plans that used Trilogy were selected. For each plan, various MIs were calculated, which included the modulation complexity score (MCS), plan-averaged beam area (PA), plan-averaged beam irregularity (PI), plan-averaged beam modulation (PM), MI quantifying multi-leaf collimator (MLC) speeds (MI), MI quantifying MLC acceleration (MI), and MI quantifying MLC acceleration and segment aperture irregularity (MI).

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Objectives: Fecal incontinence (FI) is a common debilitating disorder that tends to be underreported. Although low health literacy likely contributes to the underreporting, studies on FI knowledge among the general population remain scarce. We investigated how FI knowledge is associated with attitudes and help-seeking behaviors.

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Fibrodysplasia ossificans progressiva (FOP) syndrome is caused by mutation of the gene ACVR1, encoding a constitutive active bone morphogenetic protein type I receptor (also called ALK2) to induce heterotopic ossification in the patient. To genetically correct it, we attempted to generate the mutant ALK2-iPSCs (mALK2-iPSCs) from FOP-human dermal fibroblasts. However, the mALK2 leads to inhibitory pluripotency maintenance, or impaired clonogenic potential after single-cell dissociation as an inevitable step, which applies gene-correction tools to induced pluripotent stem cells (iPSCs).

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Background: Leucine-rich repeat kinase 2 (LRRK2) is a gene in which a mutation causes Parkinson's disease (PD), and p53 is a prototype tumor suppressor. In addition, activation of p53 in patient with PD has been reported by several studies. Because phosphorylation of p53 is critical for regulating its activity and LRRK2 is a kinase, we tested whether p53 is phosphorylated by LRRK2.

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