Background: An increased incidence of hair loss disorders has been noted among patients with coronavirus disease 2019 (COVID-19) and individuals vaccinated against COVID-19. However, research involving large populations on this topic is lacking. Objective: To investigate the risks associated with developing hair loss disorders in patients with COVID-19 and individuals vaccinated against COVID-19. Methods: This nationwide, population-based, cross-sectional study included patients diagnosed with COVID-19 and healthy individuals without a history of COVID-19 infection registered in the Korean National Health Insurance Service (NHIS) database between January 1, 2021, and December 31, 2021. COVID-19 infection and vaccine databases were integrated using this NHIS database. The odds ratios of hair loss disorders were compared using multivariate logistic regression models. Results: COVID-19 infection was associated with an increased risk of total alopecia (adjusted odds ratio [aOR], 1.076; 95% confidence interval [CI], 1.002–1.156), although this association was not significant after propensity score matching. No significant associations were found between COVID-19 infection and alopecia areata or telogen effluvium. However, COVID-19 vaccination was positively correlated with total alopecia (aOR, 1.266; 95% CI, 1.191–1.346), alopecia areata (aOR, 1.243; 95% CI, 1.154–1.339), and telogen effluvium (aOR, 1.495; 95% CI, 1.133–1.974). Conclusion COVID-19 vaccination was positively correlated with hair loss disorders but not COVID-19 infection. However, given the advantages of vaccines in reducing COVID-19 mortality and morbidity, alopecia may be relatively reversible and less severe. Physicians need to understand the benefits and possible side effects of the COVID-19 vaccine.

Background: Nasolabial folds (NLFs) constitute a pivotal aspect of facial aesthetics and are the primary focal points in facial rejuvenation procedures. Collagen-stimulating fillers have gained popularity due to their long-lasting effects and biocompatibility. Objective: This study aimed to comprehensively evaluate the therapeutic efficacy and safety profiles of collagenstimulating fillers for NLF correction. Methods: A thorough search of the databases including PubMed, Embase, and Cochrane was performed. Randomized controlled trials published between 2000 and 2023 on the treatment outcomes of collagen-stimulating fillers for NLFs were included. A systematic review and meta-analysis were conducted using the Wrinkle Severity Rating Scale (WSRS), Global Aesthetic Improvement Scale (GAIS), and adverse events. Results: Among the 144 pertinent studies, nine met the inclusion criteria, including 299 participants for polycaprolactone (PCL), 291 for poly L-lactic acid (PLLA), and 382 for calcium hydroxylapatite (CaHA). PCL showed significantly higher improvement in GAIS (risk ratio [RR], 3.14; 95% confidence interval [CI], 2.29∼4.30; p＜0.001) and WSRS (mean difference, 0.71; 95% CI, 0.36∼1.06; p＜0.001) at a 12-month interval compared with hyaluronic acid (HA). CaHA showed marked 12-month GAIS improvement versus HA (RR, 1.51; 95% CI, 1.21∼1.88; p＜0.001). PLLA exhibited superior wrinkle improvement compared with HA at week 24, especially in individuals under 52 years of age. No severe complications occurred. Conclusion Collagen-stimulating fillers have the potential to be safe, effective, and long-lasting options for NLF correction. Nevertheless, due to the limited data and heterogeneity among the included studies, cautious interpretation is required. Further high-quality clinical trials are required to validate these findings.

Background: Topical timolol is widely used for treatment of superficial infantile hemangioma (IH). However, little is known about factors that affect the response to topical timolol treatment. Objective: This study aimed to investigate the efficacy, safety, and predictive value for good response to topical timolol for IH. Methods: A retrospective review of medical records and clinical photos of 328 patients with IH treated with topical timolol 0.5% solution was conducted. Serial clinical photographs were compared with those at the initial visit using a 100-mm visual analogue scale (VAS). Treatment response was defined as an improvement of at least 75% from baseline in IH lesions within 12 months of treatment. Results: Overall, IH patients treated with topical timolol showed significant improvement from baseline, showing that the final VAS score within 12 months of treatment was 69.7±20.4. The multivariable logistic regression analysis showed age at initiation of treatment (p=0.007), length of gestation and fetal growth (p=0.03), depth (p=0.01), and flexural area (p=0.007) were significantly associated with treatment response. Only four patients (1.1%) reported local irritation. Conclusion This study demonstrated that topical timolol treatment was an effective and well-tolerated treatment for IHs. Physicians are encouraged to consider several patient- or lesional factors that might affect treatment response to achieve better clinical outcomes.

The high percentage of Vermamoeba was found in tap water in Korea. This study investigated whether Vermamoeba induced allergic airway inflammation in mice. We selected 2 free-living amoebas (FLAs) isolated from tap water, which included Korean FLA 5 (KFA5; Vermamoeba vermiformis) and 21 (an homolog of Acanthamoeba lugdunensis KA/ E2). We axenically cultured KFA5 and KFA21. We applied approximately 1 × 106 to mice’s nasal passages 6 times and investigated their pathogenicity. The airway resistance value was significantly increased after KFA5 and KFA21 treatments. The eosinophil recruitment and goblet cell hyperplasia were concomitantly observed in bronchial alveolar lavage (BAL) fluid and lung tissue in mice infected with KFA5 and KFA21. These infections also activated the Th2-related interleukin 25, thymic stromal lymphopoietin, and thymus and activation-regulated chemokines gene expression in mouse lung epithelial cells. The CD4+ interleukin 4+ cell population was increased in the lung, and the secretion of Th2-, Th17-, and Th1-associated cytokines were upregulated during KFA5 and KFA21 infection in the spleen, lung-draining lymph nodes, and BAL fluid. The pathogenicity (allergenicity) of KFA5 and KFA21 might not have drastically changed during the long-term in vitro culture. Our results suggested that Vermamoeba could elicit allergic airway inflammation and may be an airway allergen.

Background: The C-C motif chemokine ligand 11 (CCL11) has been receiving attention as a potential pro-aging factor. Accordingly, it may be involved in muscle metabolism and sarcopenia, a key component of aging phenotypes. To clarify this potential, we investigated the effects of CCL11 on in vitro muscle biology and its clinical relevance for sarcopenia parameters in older adults. Methods: Myogenesis was induced in mouse C2C12 myoblasts with 2% horse serum. Human blood samples were collected from 79 participants who underwent a functional assessment. Thereafter, CCL11 level was measured using a quantikine ELISA kit. Sarcopenia was defined using the Asian-specific guideline. Results: Recombinant CCL11 treatment significantly stimulated myogenesis in a dose-dependent manner, and consistently increased the expression of myogenic differentiation markers. Among the C-C chemokine receptors (CCRs), CCR5, not CCR2 and CCR3, was predominantly expressed in muscle cells. Further, the CCR5 inhibitor blocked recombinant CCL11-stimulated myogenesis. In a clinical study, serum CCL11 level was not significantly different according to the status of sarcopenia, low muscle mass, weak muscle strength, and poor physical performance, and was not associated with skeletal muscle index, grip strength, short physical performance battery score, gait speed, and time to complete 5 chair stands, after adjusting for sex, age, and body mass index. Conclusion Contrary to expectations, CCL11 exerted beneficial effects on muscle metabolism at least in vitro system. However, its impact on human muscle health was not evident, suggesting that circulating CCL11 may not be a useful biomarker for sarcopenia risk assessment in older adults.

Background: Despite clinical evidence indicating poor muscle health in subjects with primary aldosteronism (PA), it is still unclear whether the role of aldosterone in muscle metabolism is direct or mediated indirectly via factors, such as electrolyte imbalance or impaired glucose uptake. As one approach to clarify this issue, we investigated the effect of aldosterone on in vitro myogenesis and the potential mechanism explaining it. Methods: Myogenesis was induced in mouse C2C12 myoblasts with 2% horse serum. Immunofluorescence, quantitative reversetranscription polymerase chain reaction, Western blot, viability, and migration analyses were performed for experimental research. Results: Recombinant aldosterone treatment suppressed muscle differentiation from mouse C2C12 myoblasts in a dose-dependent manner, and consistently reduced the expression of myogenic differentiation markers. Furthermore, aldosterone significantly increased intracellular reactive oxygen species (ROS) levels in myotubes, and treatment with N-acetyl cysteine, a potent biological thiol antioxidant, reversed the decrease of myotube area, myotube area per myotube, nucleus number per myotube, and fusion index due to aldosterone through decreasing oxidative stress. A binding enzyme-linked immunosorbent assay confirmed that mineralocorticoid receptor (MR) interacted with aldosterone in C2C12 myoblasts, while eplerenone, an MR inhibitor, blocked aldosterone-stimulated intracellular ROS generation during myogenesis and markedly attenuated the suppression of in vitro myogenesis by aldosterone. Conclusion These findings support the hypothesis that hypersecretion of aldosterone, like PA, directly contributes to muscular deterioration and suggest that antioxidants and/or MR antagonists could be effective therapeutic options to reduce the risk of sarcopenia in these patients.

Background: The C-C motif chemokine ligand 11 (CCL11) has been receiving attention as a potential pro-aging factor. Accordingly, it may be involved in muscle metabolism and sarcopenia, a key component of aging phenotypes. To clarify this potential, we investigated the effects of CCL11 on in vitro muscle biology and its clinical relevance for sarcopenia parameters in older adults. Methods: Myogenesis was induced in mouse C2C12 myoblasts with 2% horse serum. Human blood samples were collected from 79 participants who underwent a functional assessment. Thereafter, CCL11 level was measured using a quantikine ELISA kit. Sarcopenia was defined using the Asian-specific guideline. Results: Recombinant CCL11 treatment significantly stimulated myogenesis in a dose-dependent manner, and consistently increased the expression of myogenic differentiation markers. Among the C-C chemokine receptors (CCRs), CCR5, not CCR2 and CCR3, was predominantly expressed in muscle cells. Further, the CCR5 inhibitor blocked recombinant CCL11-stimulated myogenesis. In a clinical study, serum CCL11 level was not significantly different according to the status of sarcopenia, low muscle mass, weak muscle strength, and poor physical performance, and was not associated with skeletal muscle index, grip strength, short physical performance battery score, gait speed, and time to complete 5 chair stands, after adjusting for sex, age, and body mass index. Conclusion Contrary to expectations, CCL11 exerted beneficial effects on muscle metabolism at least in vitro system. However, its impact on human muscle health was not evident, suggesting that circulating CCL11 may not be a useful biomarker for sarcopenia risk assessment in older adults.

Background: Despite clinical evidence indicating poor muscle health in subjects with primary aldosteronism (PA), it is still unclear whether the role of aldosterone in muscle metabolism is direct or mediated indirectly via factors, such as electrolyte imbalance or impaired glucose uptake. As one approach to clarify this issue, we investigated the effect of aldosterone on in vitro myogenesis and the potential mechanism explaining it. Methods: Myogenesis was induced in mouse C2C12 myoblasts with 2% horse serum. Immunofluorescence, quantitative reversetranscription polymerase chain reaction, Western blot, viability, and migration analyses were performed for experimental research. Results: Recombinant aldosterone treatment suppressed muscle differentiation from mouse C2C12 myoblasts in a dose-dependent manner, and consistently reduced the expression of myogenic differentiation markers. Furthermore, aldosterone significantly increased intracellular reactive oxygen species (ROS) levels in myotubes, and treatment with N-acetyl cysteine, a potent biological thiol antioxidant, reversed the decrease of myotube area, myotube area per myotube, nucleus number per myotube, and fusion index due to aldosterone through decreasing oxidative stress. A binding enzyme-linked immunosorbent assay confirmed that mineralocorticoid receptor (MR) interacted with aldosterone in C2C12 myoblasts, while eplerenone, an MR inhibitor, blocked aldosterone-stimulated intracellular ROS generation during myogenesis and markedly attenuated the suppression of in vitro myogenesis by aldosterone. Conclusion These findings support the hypothesis that hypersecretion of aldosterone, like PA, directly contributes to muscular deterioration and suggest that antioxidants and/or MR antagonists could be effective therapeutic options to reduce the risk of sarcopenia in these patients.

Background: Lichen striatus (LS) is a linear, inflammatory dermatosis that mainly affects children. To date, there are limited data comparing treatment outcomes between topical agents for pediatric LS. Objective: To investigate the clinical features and treatment outcomes associated with the use of topical agents for pediatric LS. Methods: We retrospectively reviewed the medical records and clinical photographs of 60 pediatric patients classified into three groups according to the topical agent used. Treatment response was evaluated by comparing subjective symptoms and clinical photographs obtained at each visit. Results: A good response (＞75% clinical improvement from baseline) was achieved in 55%, 46.2%, and 42.9% of patients from the calcipotriol, corticosteroid, and calcineurin inhibitor groups, respectively. There were no statistically significant differences in treatment duration among groups. However, when compared to other drugs, calcipotriol showed a trend towards shortening the disease course duration. Conclusion Topical use of calcipotriol, as well as corticosteroids and calcineurin inhibitors, may represent useful treatment options for pediatric LS, although further studies are required to confirm their efficacy and long-term safety.

Background: In February 2020, a coronavirus disease 2019 (COVID-19) outbreak was reported in fitness centers in Cheonan, Korea. Methods: From February 24 to March 13, an epidemiological investigation was conducted on the fitness center outbreak. All those who were screened were tested for severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) using real-time reverse transcriptase polymerase chain reaction. Contacts were traced and self-isolated for 14 days. We determined the epidemiological characteristics of confirmed cases of SARS-CoV-2 infection, and estimated the time-dependent reproduction number to assess the transmission dynamics of the infection. Results: A total of 116 cases were confirmed, and 1,687 contacts were traced. The source cases were 8 Zumba instructors who led aerobics classes in 10 fitness centers, and had the largest average number of contacts. A total of 57 Zumba class participants, 37 of their family members, and 14 other contacts were confirmed as cases. The attack rate was 7.3%. The contacts at Zumba classes and homes had a higher attack rate than other contacts. The mean serial interval (± standard deviation) were estimated to be 5.2 (± 3.8) days. The time-dependent reproduction number was estimated to be 6.1 at the beginning of the outbreak, but it dropped to less than 1, 2 days after the epidemiological investigation was launched. Conclusion The results suggest that the COVID-19 outbreak was effectively contained with rigorous contact tracing, isolating, and testing in combination with social distancing without a lock-down.