Protective Effects of Purple Corn (Zea mays L.) Byproduct Extract on Blue Light-Induced Retinal Damage in A2E-Accumulated ARPE-19 Cells.

This study investigated the antioxidative characteristics of Zea mays L. purple corn cob and husk extract (PCHE) and its potential protective effects against blue light (BL)-induced damage in N-retinylidene-N-retinylethanolamine (A2E)-accumulated ARPE-19 retinal pigment epithelial cells. PCHE had a 2,2-diphenyl-1-picrylhydrazyl radical-scavenging capacity and Trolox equivalent antioxidant capacity of 1.28±0.43 mM Trolox equivalents (TE)/g and 2,545.41±34.13 mM TE/g, respectively. Total content of anthocyanins, polyphenols, and flavonoids in the PCHE was 11.13±0.10 mg cyanidin-3-glucoside equivalents/100 g, 227.90±7.38 mg gallic acid equivalents/g, and 117.75±2.46 mg catechin equivalents/g, respectively. PCHE suppressed the accumulation of A2E and the photooxidation caused by BL in a dose-dependent manner. After initial treatment with 25 µM/mL A2E and BL, ARPE-19 cells showed increased cell viability following additional treatment with 15 µg/mL PCHE while the expression of the p62 sequestosome 1 decreased, whereas that of heme oxygenase-1 protein increased compared with that in cells without PCHE treatment. This suggests that PCHE may slow the autophagy induced by BL exposure in A2E-accumulated retinal cells and protect them against oxidative stress.

Exploring the Relationship between Fundamental Movement Skills and Health-Related Fitness among First and Second Graders in Korea: Implications for Healthy Childhood Development.

This study investigated the relationship between fundamental movement skills (FMSs) and health-related fitness (HRF) among first and second graders in South Korean elementary schools. It aimed to provide foundational data for developing physical education programs tailored to the motor development stages and fitness levels of younger elementary school students. This study utilized secondary data from the physical activity competence evaluation conducted by the Health Physical Activity Institute (HPAI). In October 2023, the HPAI evaluated the fundamental movement skills (jumping, running, hopping, static balance, dynamic balance, overhand throwing, and kicking) and health-related fitness (muscular strength, cardiorespiratory endurance, and flexibility) of 291 first and second-grade students. The collected data were analyzed through frequency and multiple regression analyses performed using SPSS software. The results revealed that higher scores in jumping and hopping are associated with greater muscular strength, cardiorespiratory endurance, and flexibility. Running had no significant effect on HRF elements. Higher scores in static balance (i.e., that used in single-leg stance) were associated with increased muscular strength, cardiorespiratory endurance, and flexibility, but dynamic balance (balance beam walking) did not have a significant effect. Higher scores in overhand throwing were associated with greater muscular strength and cardiorespiratory endurance, but kicking did not show a significant association. Overall, these findings emphasize the importance of prioritizing jumping and static balance in physical education for the well-rounded health development of first and second graders. Based on the results derived from this study, it is expected to serve as a theoretical basis for including "jumping" and "static balance" in the first and second grade curriculum of elementary schools, thereby providing essential guidance.

Changes in the Average Body Mass Index of Fifth- and Sixth-Grade Korean Elementary School Students: The Role of Physical Education in Student Health.

This study aimed to emphasize the importance of physical education in maintaining sufficient physical activity by examining the average BMI of fifth- and sixth-grade elementary school students in Korea over multiple years. This study investigated changes in the average BMI of fifth- and sixth-grade elementary school students in Korea. It provided foundational data to suggest the role of physical education in student health and set future directions. The 2019-2021 Physical Activity Promotion System (PAPS) of the Korean Ministry of Education was used. Data corresponding to fifth- and sixth-grade students (124,693 from 2019, 126,226 from 2020, and 117,809 from 2021) in 1208 elementary schools in Korea were collected. Repeated measures ANOVA was conducted for the data analysis. The study findings are as follows: First, the average BMI of fifth- and sixth-grade elementary school students in Korea increased significantly in 2021 compared with 2019 and 2020. Second, changes in the yearly average BMI showed a significant difference depending on gender and grade. Obesity among fifth- and sixth-grade elementary school students in Korea increased steadily during 2019-2021, which may be due to a decrease in students' physical activity. Male students showed a steeper increase regardless of grade. During the study period, limited physical activity at school increased obesity rates. Physical education must play a role in students' health in preparation for future changes.

Tannic-Acid-Enriched Poly(vinyl alcohol) Nanofibrous Membrane as a UV-Shie lding and Antibacterial Face Mask Filter Material.

Face masks are increasingly important in the battle against infectious diseases and air pollution. Nanofibrous membranes (NFMs) are promising filter layers for removing particulate matter (PM) without restricting air permeability. In this study, tannic-acid-enriched poly(vinyl alcohol) (PVA-TA) NFMs were fabricated by electrospinning PVA solutions containing large amounts of tannic acid (TA), a multifunctional polyphenol compound. We were able to prepare uniform electrospinning solution without coacervate formation by inhibiting the robust hydrogen bonding between PVA and TA. Notably, the NFM maintained its fibrous structure even under moist conditions after heat treatment without the use of a cross-linking agent. Further, the mechanical strength and thermal stability of the PVA NFM were improved by the introduction of TA. The functional PVA NFM with a high TA content showed excellent UV-shielding (UV-A: 95.7%, UV-B: 100%) and antibacterial activity against Escherichia coli (inhibition zone: 8.7 ± 1.2 mm) and Staphylococcus aureus (inhibition zone: 13.7 ± 0.6 mm). Moreover, the particle filtration efficiency of the PVA-TA NFM for PM0.6 particles was 97.7% at 32 L min-1 and 99.5% at 85 L min-1, indicating excellent filtration performance and a low pressure drop. Therefore, the TA-enriched PVA NFM is a promising mask filter layer material with excellent UV-blocking and antibacterial properties and has the potential for various practical applications.

PHF20 is crucial for epigenetic control of starvation-induced autophagy through enhancer activation.

Autophagy is a catabolic pathway that maintains cellular homeostasis under various stress conditions, including conditions of nutrient deprivation. To elevate autophagic flux to a sufficient level under stress conditions, transcriptional activation of autophagy genes occurs to replenish autophagy components. Thus, the transcriptional and epigenetic control of the genes regulating autophagy is essential for cellular homeostasis. Here, we applied integrated transcriptomic and epigenomic profiling to reveal the roles of plant homeodomain finger protein 20 (PHF20), which is an epigenetic reader possessing methyl binding activity, in controlling the expression of autophagy genes. Phf20 deficiency led to impaired autophagic flux and autophagy gene expression under glucose starvation. Interestingly, the genome-wide characterization of chromatin states by Assay for Transposase-Accessible Chromatin (ATAC)-sequencing revealed that the PHF20-dependent chromatin remodelling occurs in enhancers that are co-occupied by dimethylated lysine 36 on histone H3 (H3K36me2). Importantly, the recognition of H3K36me2 by PHF20 was found to be highly correlated with increased levels of H3K4me1/2 at the enhancer regions. Collectively, these results indicate that PHF20 regulates autophagy genes through enhancer activation via H3K36me2 recognition as an epigenetic reader. Our findings emphasize the importance of nuclear events in the regulation of autophagy.

Sex differences in the association between self-rated health and high-sensitivity C-reactive protein levels in Koreans: a cross-sectional study using data from the Korea National Health and Nutrition Examination Survey.

BACKGROUND: No studies have investigated the association between self-rated health (SRH) and high-sensitivity C-reactive protein (hs-CRP) levels in South Koreans. We explored this association and analyzed differences between sexes. METHODS: Using cross-sectional data from the 2015-2017 Korea National Health and Nutrition Examination Survey, we analyzed the association between SRH and high hs-CRP levels (> 1.0 mg/L) in 14,544 Koreans aged ≥ 19 years who responded to the SRH survey and had available hs-CRP test results. Differences in sociodemographic factors were analyzed using the Pearson's chi-square test for categorical variables or the Mann-Whitney U test for continuous variables. Multiple logistic regression analysis was used to measure the association between hs-CRP levels and SRH according to sex while adjusting for other possible confounders. RESULTS: The percentage of very poor to poor SRH was higher in the high hs-CRP group (22.4%) than in the low hs-CRP group (17.66%). Among men, the risk of a high hs-CRP level increased with worse SRH (adjusted for confounders; P for trend < 0.001). After adjusting for all confounders, including chronic diseases, men with very poor SRH showed a higher odds ratio (OR) for high hs-CRP levels than those with very good SRH (fully adjusted OR, 1.74; 95% CI, 1.04-2.90). Significant correlations were absent among women. CONCLUSIONS: Poor SRH was correlated with low-grade inflammation (high hs-CRP levels) among Korean male adults. These findings could be useful for developing health improvement programs and in goal setting at a national scale.

Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan.

In cone-beam computed tomography (CBCT), the minimum threshold of the gray value of segmentation is set to convert the CBCT images to the 3D mesh reconstruction model. This study aimed to assess the accuracy of image registration of optical scans to 3D CBCT reconstructions created by different thresholds of grey values of segmentation in partial edentulous jaw conditions. CBCT of a dentate jaw was reconstructed to 3D mesh models using three different thresholds of gray value (-500, 500, and 1500), and three partially edentulous models with different numbers of remaining teeth (4, 8, and 12) were made from each 3D reconstruction model. To merge CBCT and optical scan data, optical scan images were registered to respective 3D reconstruction CBCT images using a point-based best-fit algorithm. The accuracy of image registration was assessed by measuring the positional deviation between the matched 3D images. The Kruskal-Wallis test and a post hoc Mann-Whitney U test with Bonferroni correction were used to compare the results between groups (α = 0.05). The correlations between the experimental factors were calculated using the two-way analysis of variance test. The positional deviations were lowest with the threshold of 500, followed by the threshold of 1500, and then -500. A significant interaction was found between the threshold of gray values and the number of remaining teeth on the registration accuracy. The most significant deviation was observed in the arch model with four teeth reconstructed with a gray-value threshold of -500. The threshold for the gray value of CBCT segmentation affects the accuracy of image registration of optical scans to the 3D reconstruction model of CBCT. The appropriate gray value that can visualize the anatomical structure should be set, especially when few teeth remain in the dental arch.

The effect of the improperly scanned scan body images on the accuracy of virtual implant positioning in computer-aided design software.

PURPOSE: The aim of this study was to examine the importance of the defect-free scanning of a scan body by assessing the accuracy of virtual implant positioning in computer-aided design (CAD) software when the scan body image is improperly scanned. MATERIALS AND METHODS: A scan body was digitized in a dentiform model using an intraoral scanner, and scanned images with differing levels of image deficiency were generated: 5%, 10%, and 15% deficiency in the flat or rounded area. Using a best-fit image matching algorithm on each of the deficient scan body images, corresponding virtual implants were created. The accuracy of the implant position was evaluated by comparing the linear and angular discrepancies between the actual and virtual positions of the implant. Kruskal-Wallis tests and Mann-Whitney U tests with Bonferroni correction were used to determine the statistical differences among the seven scanned image deficiency groups (α=.05). RESULTS: In general, the linear and angular discrepancies of the implant position in the software increased as the deficiency of the scan body images increased. A 15% scan body image deficiency generated larger discrepancies than deficiency of 5% and 10%. The difference of scan defect position, flat or rounded area, did not affect the accuracy of virtual implant orientation at 5% and 10% deficiency level, but did affect the accuracy at 15% deficiency level. CONCLUSION: Deficiencies in the scanned images of a scan body can decrease the accuracy of the implant positioning in CAD software when the defect is large, thus leading to the incorrect fabrication of implant prostheses.

Development of 8 ton/day gasification process to generate electricity using a gas engine for solid refuse fuel.

An 8 ton/day solid refuse fuel gasification process with air oxidant was operated under various conditions to generate electricity. Solid refuse fuels with fluff type feedstock were fabricated from municipal solid wastes. The tested experimental conditions included feedstock charging rate into the gasifier, equivalence ratio, and oxygen enrichment; varying these conditions resulted in different gasification characteristics, such as cold gas efficiency and carbon conversion ratio. Optimum conditions were a charging rate of 50 to 60% by volume (504.71 to 605.65 kg/Sm2) of feedstock in the gasifier, equivalence ratio of 0.21 to 0.33, and no oxygen enrichment. Average cold gas efficiency and carbon conversion ratio were 71.30% and 72.07%, respectively, at optimum conditions. Pollutants such as dust, tar, and gases, were analyzed at the outlet of the cleaning facility and gasifier, and their low concentrations in the producer gas were sufficient to allow for operation of the gas engine. The gasification process exhibited stable operation over 288 h, which included the facility check period. The average gasifier temperature was 825 °C, 17.14% by volume of producer gas was syngas, and gas engine power generation was 235 kWh during this period; power consumption of the entire system was 68 kWh. These results demonstrate that the gasification process for converting solid waste to energy can be operated at a commercial scale.

Molecular and Morphological Confirmation of Three Undescribed Species of Mortierella from Korea.

Three fungal isolates designated as CNUFC-YR329-1, CNUFC-PTS103-1, and CNUFC-PTS2-1 were discovered during a survey of fungal diversity of the order Mortierellales from freshwater and pine tree rhizosphere soil samples in Korea. The strains were analyzed morphologically and phylogenetically based on the internal transcribed spacer (ITS) and large subunit (LSU) of ribosomal DNA gene sequences. Based on their morphology and phylogeny, the three isolates were identified as Mortierella elongata, M. horticola, and M. humilis, respectively. To the best of our knowledge, M. elongata, M. horticola, and M. humilis, belonging to an undiscovered taxon, have not been previously described in Korea.

Applicability assessment of empty fruit bunches from palm oil mills for use as bio-solid refuse fuels.

Palm kernel shells (PKS), empty fruit bunches (EFB), and trunks are by-products of the palm oil industry and form approximately 50 wt % of fresh fruit bunch (FFB). In particular, EFB accounts for approximately 20 wt % of FFB. Although large amounts of EFB are generated from palm oil mills every year in Indonesia and Malaysia, EFB is treated as waste because commercial technologies for thermo-chemical conversion of EFB into renewable energy are still under development. A robust conversion method can transform EFB into an appealing renewable energy source. In order to secure this renewable energy source, Korea can import EFB as biomass. This paper investigates literature on the status of utilization of EFB, by-products from palm oil mills in order to identify the best available technological process to use EFB as bio-solid refuse fuels (SRF). Meanwhile, physico-chemical analyses (proximate, elemental, and calorific value analyses), biomass and heavy metal content were measured in order to assess whether EFB would be suitable for use as a bio-SRF, in accordance with the Korean quality standard for SRF. According to the analysis results, EFB showed applicability to use as bio-SRF; main analysis results - moisture (9.63 wt %), ash (5.94 wt %), biomass content (97.82 wt %) and calorific value (3668 kcal kg).

PKCα-LSD1-NF-κB-Signaling Cascade Is Crucial for Epigenetic Control of the Inflammatory Response.

The inflammatory response mediated by nuclear factor κB (NF-κB) signaling is essential for host defense against pathogens. Although the regulatory mechanism of NF-κB signaling has been well studied, the molecular basis for epigenetic regulation of the inflammatory response is poorly understood. Here we identify a new signaling axis of PKCα-LSD1-NF-κB, which is critical for activation and amplification of the inflammatory response. In response to excessive inflammatory stimuli, PKCα translocates to the nucleus and phosphorylates LSD1. LSD1 phosphorylation is required for p65 binding and facilitates p65 demethylation, leading to enhanced stability. In vivo genetic analysis using Lsd1SA/SA mice with ablation of LSD1 phosphorylation and chemical approaches in wild-type mice with inhibition of PKCα or LSD1 activity show attenuated sepsis-induced inflammatory lung injury and mortality. Together, we demonstrate that the PKCα-LSD1-NF-κB signaling cascade is crucial for epigenetic control of the inflammatory response, and targeting this signaling could be a powerful therapeutic strategy for systemic inflammatory diseases, including sepsis.

Mechanism of inhibition of taurolithocholate-induced retrieval of plasma membrane MRP2 by cyclic AMP and tauroursodeoxycholate.

Taurolithocholate (TLC) produces cholestasis by inhibiting biliary solute secretion in part by retrieving MRP2 from the plasma membrane (PM). Tauroursodeoxycholate (TUDC) and cAMP reverse TLC-induced cholestasis by inhibiting TLC-induced retrieval of MRP2. However, cellular mechanisms for this reversal are incompletely understood. Recently, we reported that TLC decreases PM-MRP2 by activating PKCε followed by phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS). Thus, cAMP and TUDC may reverse TLC-induced cholestasis by inhibiting the TLC/PKCε/MARCKS phosphorylation pathway. We tested this hypothesis by determining whether TUDC and/or cAMP inhibit TLC-induced activation of PKCε and phosphorylation of MARCKS Studies were conducted in HuH-NTCP cell line and rat hepatocytes. Activation of PKCε was determined from the translocation of PKCε to PM using a biotinylation method. Phosphorylation of MARCKS was determined by immunoblotting with a phospho-MARCKS antibody. TLC, but not cAMP and TUDC, activated PKCε and increased MARCKS phosphorylation in HuH-NTCP as well in rat hepatocytes. Treatment with TUDC or cAMP inhibited TLC-induced activation of PKCε and increases in MARCKS phosphorylation in both cell types. Based on these results, we conclude that the reversal of TLC-induced cholestasis by cAMP and TUDC involves, at least in part, inhibition of TLC-mediated activation of the PKCε/MARCKS phosphorylation pathway.

Characterization of Two Species of Acremonium (Unrecorded in Korea) from Soil Samples: A. variecolor and A. persicinum.

During a survey of fungal diversity of the order Hypocreales in Korea, two Acremonium isolates, CNUFC-1YSRS2-4 and CNUFC-GSNPF3-1, were isolated from soils collected on a bank of the Yeongsan River, Naju, and in a forest on the Mt. Daegak located on Sinsi Island, Gunsan, South Korea, respectively. Based on the morphological characteristics and sequence analysis of the internal transcribed spacer and D1/D2 domains of 28S ribosomal DNA, the isolates CNUFC-1YSRS2-4 and CNUFC-GSNPF3-1 were identified as A. variecolor and A. persicinum, respectively. These 2 species represent novel Hypocreales isolates in Korea.

Purification and characterization of buffalo liver L-arginase and its kinetic properties with dihydropyrimidine and metal ions.

Arginase (L-arginine amidinohydrolase, EC.3.5.3.1) from animal tissues such as, liver and kidney has been partially characterized by many researchers. In this study, we purified arginase to homogeneity from buffalo liver with about ~2857 purification fold and a 20% recovery by chromatographic and spectroscopic analysis were obtained. The molecular mass determined by gel filtration and SDS-PAGE was found to be 118 kDa and 47 kDa, respectively. The optimal pH and temperature of the arginase was 9.5 and 40°C, respectively. Kinetic parameters (Km and Vmax) showed activation of arginase in the reaction medium with decrease in Km (7.14, 5.26, 4.0 and control 3.22 mM) and Vmax (0.05, 0.035, 0.027 and control 0.021 mg/mL/min), while co-factor activity of arginase was optimized using metal ions like Mn²âº and Mg²âº at 2 mM, which revealed an increase in Vmax values (0.011, 0.013, 0.015 and control 0.010 mg/mL/min) and a decrease in Km values (2.22, 2.12, 1.88 and control 1.66 mM). The kinetic data suggested that the arginase activity is enhanced in the presence of dihydropyrimidine derivative and metal ions, indicating essential mode of activation.

p38 MAPK α and ß isoforms differentially regulate plasma membrane localization of MRP2.

In hepatocytes, cAMP both activates p38 mitogen-activated protein kinase (MAPK) and increases the amount of multidrug resistance-associated protein-2 (MRP2) in the plasma membrane (PM-MRP2). Paradoxically, taurolithocholate (TLC) activates p38 MAPK but decreases PM-MRP2 in hepatocytes. These opposing effects of cAMP and TLC could be mediated via different p38 MAPK isoforms (α and ß) that are activated differentially by upstream kinases (MKK3, MKK4, and MKK6). Thus we tested the hypothesis that p38α MAPK and p38ß MAPK mediate increases and decreases in PM-MRP2 by cAMP and TLC, respectively. Studies were conducted in hepatocytes isolated from C57BL/6 wild-type (WT) and MKK3-knockout (MKK3(-/-)) mice and in a hepatoma cell line (HuH7) that overexpresses sodium-taurocholate cotransporting polypeptide (NTCP) (HuH-NTCP). Cyclic AMP activated MKK3, p38 MAPK, and p38α MAPK and increased PM-MRP2 in WT hepatocytes, but failed to activate p38α MAPK or increase PM-MRP2 in MKK3(-/-) hepatocytes. In contrast to cAMP, TLC activated total p38 MAPK but decreased PM-MRP2, and did not activate MKK3 or p38α MAPK in WT hepatocytes. In MKK3(-/-) hepatocytes, TLC still decreased PM-MRP2 and activated p38 MAPK, indicating that these effects are not MKK3-dependent. Additionally, TLC activated MKK6 in MKK3(-/-) hepatocytes, and small interfering RNA knockdown of p38ß MAPK abrogated TLC-mediated decreases in PM-MRP2 in HuH-NTCP cells. Taken together, these results suggest that p38α MAPK facilitates plasma membrane insertion of MRP2 by cAMP, whereas p38ß MAPK mediates retrieval of PM-MRP2 by TLC.

Methylation-dependent regulation of HIF-1α stability restricts retinal and tumour angiogenesis.

Hypoxia-inducible factor-1α (HIF-1α) mediates hypoxic responses and regulates gene expression involved in angiogenesis, invasion and metabolism. Among the various HIF-1α posttranslational modifications, HIF-1α methylation and its physiological role have not yet been elucidated. Here we show that HIF-1α is methylated by SET7/9 methyltransferase, and that lysine-specific demethylase 1 reverses its methylation. The functional consequence of HIF-1α methylation is the modulation of HIF-1α stability primarily in the nucleus, independent of its proline hydroxylation, during long-term hypoxic and normoxic conditions. Knock-in mice bearing a methylation-defective Hif1a(KA/KA) allele exhibit enhanced retinal angiogenesis and tumour vascularization via HIF-1α stabilization. Importantly, S28Y and R30Q mutations of HIF-1α, found in human cancers, are involved in the altered HIF-1α stability. Together, these results demonstrate a role for HIF-1α methylation in regulating protein stability, thereby modulating biological output including retinal and tumour angiogenesis, with therapeutic implications in human cancer.

A simple and efficient Agrobacterium tumefaciens-mediated plant transformation of Brassica rapa ssp. pekinensis.

The present study aims to investigate the numerous factors influencing Agrobacterium tumefaciens-mediated genetic transformation of Chinese cabbage (Brassica rapa ssp. pekinensis). Factors affecting transformation efficiency, such as age of explants, Agrobacterium concentration, and effect of acetosyringone, pre-cultivation, infection and co-cultivation time of Agrobacterium were examined. The pre-cultured hypocotyls from young seedlings prior to exposure to Agrobacterium showed higher shoot regeneration. The plant transformation with the modest A. tumefaciens concentrations (0.8 OD) and the 3 days co-cultivation periods increased transformation efficiency. Plant growth hormones [1-naphthyl acetic acid (NAA) and 6-benzyl amino purine (BAP)] were essential for callus and shoot formation. Root formation was effective in half strength MS medium without supplementation of root-inducing hormones. To maintain selection pressure, plant subculture was carried out every 2 weeks with selective antibiotics. The putative transgenic plants were acclimatized in the greenhouse. Polymerase chain reaction was performed to confirm the integration of T-DNA into the genome of transgenic plants. A transformation efficiency of 15 % was obtained. This protocol allows effective transformation and indirect regeneration of Brassica rapa.

An Update on Potential Perspectives of Glucosinolates on Protection against Microbial Pathogens and Endocrine Dysfunctions in Humans.

Glucosinolates are the major bioactive secondary metabolites found in the Brassicaceae family and studied extensively in biosynthetic and application perspectives. Because of their potential applications in the welfare of plants (protection against plant pathogens) and human life (prevention of cancer and other diseases), these compounds attracted much interest in the scientific community. In this review, we presented updates on glucosinolate derivatives in protection against microbial pathogens and endocrine related diseases in human. Further, the mechanism of action of glucosinolate derivatives and the strategies to improve their efficiency through modern approaches were discussed. Finally, the genetic enrichment of their contents in plant systems has also been discussed.

Scattered atypical melanocytes with hyperchromatic nuclei in the nail matrix: diagnostic clue for early subungual melanoma in situ.

BACKGROUND: The lack of highly specific clinical and histopathological criteria has contributed to the delay in diagnosis of subungual melanoma in situ in its early stages. METHODS: Eighteen cases of subungual melanoma in situ, the largest series reported to date, were analyzed to characterize the clinical and histopathological findings of early stages of subungual melanoma in situ along with five cases of nail matrix nevus and five cases of subungual lentigo serving as histologic control. RESULTS: Clinically, longitudinal melanonychia was present in all 18 cases of subungual melanoma in situ, consisting of irregular dark brown to black streaks within a brown background with (11 cases) or without Hutchinson's sign. Histopathologically, variable shaped and sized, hyperchromatic nuclei surrounded by retraction artifact were present in all cases. Nine cases showed a significant increase in the number of atypical melanocytes with marked nuclear atypia, while the rest of the cases showed less noticeable changes in nail matrix including lower density of melanocytes and/or mild nuclear atypia. In 15 cases, the nuclear enlargement in some of the melanocytes was greater than two times that of the neighboring matrix cells. In the remaining three cases, the nuclei were enlarged to a much lesser degree. All cases displayed areas of haphazard and uneven distribution of solitary melanocytes and, although not observed in all cases, some degree of pagetoid spread was present in majority of the cases. In contrast, nail matrix nevi showed well-formed nests consisting of relatively monomorphous melanocytes with abundant cytoplasm and subungual lentigos consisted of subtle increase in the number of dendritic melanocytes in solitary units within the lower layers of the nail matrix. CONCLUSION: Increase in the number of scattered atypical melanocytes with large hyperchromatic nuclei in a partial nail matrix may provide a diagnostic clue to subungual melanoma in situ in concert with its clinical suspicion.