Publications by authors named "Pak O"

Micro- and nanorobots excel in navigating the intricate and often inaccessible areas of the human body, offering immense potential for applications such as disease diagnosis, precision drug delivery, detoxification, and minimally invasive surgery. Despite their promise, practical deployment faces hurdles, including achieving stable propulsion in complex in vivo biological environments, real-time imaging and localization through deep tissue, and precise remote control for targeted therapy and ensuring high therapeutic efficacy. To overcome these obstacles, we introduce a hydrogel-based, imaging-guided, bioresorbable acoustic microrobot (BAM) designed to navigate the human body with high stability.

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Rationale: Glioblastoma is one of the most aggressive human brain tumors. The prognosis is unfavorable and treatment effects are relatively low. However, temozolomide (TMZ) chemotherapy may prolong patients' survival.

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Introduction: Glioblastoma (GB) is one of the deadliest human brain tumors. The prognosis is unfavorable, chemotherapy with temozolomide (TMZ) may extend the survival period for a patient. The paper aims to evaluate the survival rates among relapsing GB patients, who have been treated with valproic acid (VPA), and to study its effect on tumor cells when combined with TMZ and celecoxib (CXB).

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Exposure of cell membranes to reactive oxygen species can cause oxidation of membrane lipids. Oxidized lipids undergo drastic conformational changes, compromising the mechanical integrity of the membrane and causing cell death. For giant unilamellar vesicles, a classic cell mimetic system, a range of mechanical responses under oxidative assault has been observed including formation of nanopores, transient micron-sized pores, and total sudden catastrophic collapse (i.

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Microorganisms and synthetic microswimmers often encounter complex environments consisting of networks of obstacles embedded into viscous fluids. Such settings include biological media, such as mucus with filamentous networks, as well as environmental scenarios, including wet soil and aquifers. A fundamental question in studying their locomotion is how the impermeability of these porous media impacts their propulsion performance compared with the case of that in a purely viscous fluid.

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Background: The precise origin of newly formed ACTA2+ (alpha smooth muscle actin-positive) cells appearing in nonmuscularized vessels in the context of pulmonary hypertension is still debatable although it is believed that they predominantly derive from preexisting vascular smooth muscle cells (VSMCs).

Methods: mice were used to lineage trace GLI1+ (glioma-associated oncogene homolog 1-positive) cells in the context of pulmonary hypertension using 2 independent models of vascular remodeling and reverse remodeling: hypoxia and cigarette smoke exposure. Hemodynamic measurements, right ventricular hypertrophy assessment, flow cytometry, and histological analysis of thick lung sections followed by state-of-the-art 3-dimensional reconstruction and quantification using Imaris software were used to investigate the contribution of GLI1+ cells to neomuscularization of the pulmonary vasculature.

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Glioblastoma (GB) is one of the most adverse diagnoses in oncology. Complex current treatment results in a median survival of 15 months. Resistance to treatment is associated with the presence of cancer stem cells (CSCs).

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The integration of an ingestible dosage form with sensing, actuation, and drug delivery capabilities can enable a broad range of surgical-free diagnostic and treatment strategies. However, the gastrointestinal (GI) tract is a highly constrained and complex luminal construct that fundamentally limits the size of an ingestible system. Recent advancements in mesoscale magnetic crawlers have demonstrated the ability to effectively traverse complex and confined systems by leveraging magnetic fields to induce contraction and bending-based locomotion.

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Background: COPD is an incurable disease and a leading cause of death worldwide. In mice, fibroblast growth factor (FGF)10 is essential for lung morphogenesis, and in humans, polymorphisms in the human gene correlate with an increased susceptibility to develop COPD.

Methods: We analysed FGF10 signalling in human lung sections and isolated cells from healthy donor, smoker and COPD lungs.

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The elastohydrodynamic interaction between an elastic filament and its surrounding fluid was exploited to develop the first microswimmers. These flexible microswimmers are typically actuated magnetically at one end and their propulsion behavior is relatively well understood. In this work, we move beyond the traditional single-end actuation setup and explore the propulsion characteristics of an elastic filament driven by magnetic torques at both ends.

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The mitochondrial adaptor protein p66Shc has been suggested to control life span in mice via the release of hydrogen peroxide. However, the role of p66Shc in lung aging remains unsolved. Thus, we investigated the effects of p66Shc on the aging of the lung and pulmonary circulation.

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Biological microswimmers can coordinate their motions to exploit their fluid environment-and each other-to achieve global advantages in their locomotory performance. These cooperative locomotion require delicate adjustments of both individual swimming gaits and spatial arrangements of the swimmers. Here we probe the emergence of such cooperative behaviors among artificial microswimmers endowed with artificial intelligence.

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Article Synopsis
  • Tobacco smoking and air pollution are major contributors to chronic obstructive pulmonary disease (COPD), yet not all smokers develop the condition, highlighting the need to explore protective mechanisms against oxidative stress.
  • The study investigated various cohorts by analyzing sputum, lung tissue, and blood samples to measure levels of 3-nitrotyrosine (3-NT), an indicator of oxidative stress, and established a new cell model resistant to cigarette smoke extract (CSE) to understand the relationship between oxidative stress and COPD.
  • Findings suggest that high levels of HO-1 (heme oxygenase-1) are linked to reduced oxidative stress in CSE-resistant cells, while increased expression of CEACAM6 in epithelial cells appears to exacerbate oxidative stress and
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Article Synopsis
  • The review outlines the historical development of new chemical reagents that enhance the use of scanning electron microscopy (SEM) in medical and biological research, especially in ophthalmology.
  • It addresses the challenges of applying SEM in clinical medicine, particularly in preparing biological samples for analysis.
  • The article also highlights practical examples of SEM's application in clinical ophthalmology and discusses its future potential, especially with the integration of artificial intelligence in diagnostic processes.
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Background: Electronic cigarette (e-cigarette) vapour is gaining popularity as an alternative to tobacco smoking and can induce acute lung injury. However, the specific role of nicotine in e-cigarette vapour and its long-term effects on the airways, lung parenchyma and vasculature remain unclear.

Results: exposure to nicotine-containing e-cigarette vapour extract (ECVE) or to nicotine-free e-cigarette vapour extract (NF ECVE) induced changes in gene expression of epithelial cells and pulmonary arterial smooth muscle cells (PASMCs), but ECVE in particular caused functional alterations ( a decrease in human and mouse PASMC proliferation by 29.

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Trauma triggers critical molecular and cellular signaling cascades that drive biological outcomes and recovery. Variations in the gene expression of common endogenous reference housekeeping genes (HKGs) used in data normalization differ between tissue types and pathological states. Systematically, we investigated the gene stability of nine HKGs (, , , , , , , , and ) from tissues prone to remote organ dysfunction (lung, liver, kidney, and muscle) following extremity trauma.

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Tourniquets are critical for the control of traumatic extremity hemorrhage. In this study, we sought to determine, in a rodent blast-related extremity amputation model, the impact of prolonged tourniquet application and delayed limb amputation on survival, systemic inflammation, and remote end organ injury. Adult male Sprague Dawley rats were subjected to blast overpressure (120±7 kPa) and orthopedic extremity injury consisting femur fracture, one-minute soft tissue crush injury (20 psi), ± 180 min of tourniquet-induced hindlimb ischemia followed by delayed (60 min of reperfusion) hindlimb amputation (dHLA).

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Background: The brain-derived neurotrophic factor (BDNF) may promote development of pulmonary hypertension and right ventricular (RV) failure. However, BDNF plasma levels were decreased in patients with left ventricular (LV) failure. Therefore, we investigated BDNF plasma levels in pulmonary hypertension patients and the role of BDNF in mouse models of pulmonary hypertension and isolated RV failure.

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The mechanical properties of red blood cells (RBCs) play key roles in their biological functions in microcirculation. In particular, RBCs must deform significantly to travel through microcapillaries with sizes comparable with or even smaller than their own. Although the dynamics of RBCs in microcapillaries have received considerable attention, the effect of membrane viscoelasticity has been largely overlooked.

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Contaminants and other agents are often present at the interface between two fluids, giving rise to rheological properties such as surface shear and dilatational viscosities. The dynamics of viscous drops with interfacial viscosities has attracted greater interest in recent years, due to the influence of surface rheology on deformation and the surrounding flows. We investigate the effects of shear and dilatational viscosities on the electro-deformation of a viscous drop using the Taylor-Melcher leaky dielectric model.

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Background: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. In addition to chronic bronchitis and emphysema, patients often develop at least mild pulmonary hypertension (PH). We previously demonstrated that inhibition of inducible nitric oxide synthase (iNOS) prevents and reverses emphysema and PH in mice.

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Automated manipulation of small particles using external (e.g., magnetic, electric and acoustic) fields has been an emerging technique widely used in different areas.

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The role of microparticles (MPs) and cold in high altitude pulmonary hypertension (HAPH) remains unexplored. We investigated the impact of long-term cold exposure on the pulmonary circulation in lowlanders and high-altitude natives and the role of MPs. Pulmonary hemodynamics were evaluated using Doppler echocardiography at the end of the colder and warmer seasons.

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Acclimation to acute hypoxia through cardiorespiratory responses is mediated by specialized cells in the carotid body and pulmonary vasculature to optimize systemic arterial oxygenation and thus oxygen supply to the tissues. Acute oxygen sensing by these cells triggers hyperventilation and hypoxic pulmonary vasoconstriction which limits pulmonary blood flow through areas of low alveolar oxygen content. Oxygen sensing of acute hypoxia by specialized cells thus is a fundamental pre-requisite for aerobic life and maintains systemic oxygen supply.

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