Pediatric dual-energy X-ray absorptiometry: interpretation and clinical and research application

Peak bone mass is established predominately during childhood and adolescence. It is an important determinant of future resistance to osteoporosis and fractures to gain bone mass during growth. The issue of low bone density in children and adolescents has recently attracted much attention and the use of pediatric dual-energy X-ray absorptiometry (DXA) is increasing. The process of interpretation of pediatric DXA results is different from that of adults because normal bone mineral density (BMD) of children varies by age, body size, pubertal stage, skeletal maturation, sex, and ethnicity. Thus, an appropriate normal BMD Z-score reference value with Z-score should be used to detect and manage low BMD. Z-scores below -2.0 are generally considered a low BMD to pediatrician even though diagnoses of osteoporosis in children and adolescents are usually only made in the presence of at least one fragility fracture. This article will review the basic knowledge and practical guidelines on pediatric DXA based on the International Society for Clinical Densitometry (ISCD) Pediatric Official Positions. Also discussed are the characteristics of normal Korean children and adolescents with respect to BMD development. The objective of this review is to help pediatricians to understand when DXA will be useful and how to interpret pediatric DXA reports in the clinical practice for management of children with the potential to develop osteoporosis in adulthood

Entrainment, mixing, and the evolution of the cloud droplet size distribution

Clouds significantly influence Earth's climate by affecting radiation and moisture budgets, yet their representation remains a major source of uncertainty in climate models, as many processes are poorly understood. Advancing our understanding of cloud microphysics requires examining processes across a large range of scales, from individual droplet interactions to large-scale atmospheric dynamics. Among these, the entrainment and mixing process plays a critical role in shaping the cloud droplet size distribution (DSD) which affects cloud optical properties and precipitation efficiency. Most conventional models assume homogeneous mixing; however, mixing can also occur inhomogeneously. Inhomogeneous mixing alters the DSD differently than homogeneous mixing, often reducing the cloud's reflectivity. Thus, accurately representing these distinct mixing scenarios and understanding their prevalence are essential for improving cloud model accuracy. Representing inhomogeneous mixing is challenging, as its typical lengthscale lies below the resolution of even advanced cloud models. Here, we apply the L3 model—a novel large-eddy simulation framework coupled with particle-based cloud microphysics and a subgrid statistical turbulence model—to simulate the full range of turbulent mixing scales relevant to inhomogeneous mixing. Clouds significantly influence Earth's climate by affecting radiation and moisture budgets, yet their representation remains a major source of uncertainty in climate models, as many processes are poorly understood. Advancing our understanding of cloud microphysics requires examining processes across a large range of scales, from individual droplet interactions to large-scale atmospheric dynamics. Among these, the entrainment and mixing process plays a critical role in shaping the cloud droplet size distribution (DSD) which affects cloud optical properties and precipitation efficiency. Most conventional models assume homogeneous mixing; however, mixing can also occur inhomogeneously. Inhomogeneous mixing alters the DSD differently than homogeneous mixing, often reducing the cloud's reflectivity. Thus, accurately representing these distinct mixing scenarios and understanding their prevalence are essential for improving cloud model accuracy. Representing inhomogeneous mixing is challenging, as its typical lengthscale lies below the resolution of even advanced cloud models. Here, we apply the L3 model—a novel large-eddy simulation framework coupled with particle-based cloud microphysics and a subgrid statistical turbulence model—to simulate the full range of turbulent mixing scales relevant to inhomogeneous mixing. Using the L3 model, we investigate how entrainment and mixing alter the DSD shape in distinct ways. Our results confirm that homogeneous mixing broadens the DSD, while inhomogeneous mixing reduces droplet concentration with negligible change to DSD width. Additionally, we identify a new mixing scenario that narrows the DSD width. Additionally, we show that while homogeneous mixing is prevalent, inhomogeneous mixing increases over the life cycle of shallow cumulus clouds. This is consistent with previous observational suggestions. Moreover, we find that increasingly inhomogeneous mixing is related to the degree of cloud dilution, influenced either by the cumulative effect of entrainment or by a drier, aerosol-laden surrounding environment. Finally, by tracking individual droplets, we investigate DSD evolution in stratocumulus clouds, where droplets strongly or weakly affected by entrainment and mixing can exhibit distinct evolutions in DSD shape. While these resemble different mixing scenarios, they are not necessarily a result of mixing, but rather a result of large-scale processes. In conclusion, our findings demonstrate that the L3 model not only supports existing theories of entrainment and mixing but also reveals previously overlooked complexities. Thus, L3 can be considered a valuable tool for addressing further key questions in cloud microphysics and advancing our understanding of clouds' role in the climate system.Wolken haben einen erheblichen Einfluss auf das Erdklima, da sie den Strahlungs- und Wasserhaushalt verändern. Dennoch bleibt ihre Darstellung eine große Unsicherheitsquelle in Klimamodellen, da viele Prozesse noch unzureichend verstanden sind. Um unser Verständnis der Wolkenmikrophysik zu vertiefen, müssen Prozesse skalenüberübergreifend untersucht werden, von Wechselwirkungen einzelner Tropfen bis hin zu großräumigen atmosphärischen Dynamiken. Dabei spielen Eintrainment- und Mischungsprozesse eine entscheidende Rolle bei der Formung der Tröpfchengrößenverteilung (Droplet Size Distribution; DSD), welche wiederum die optischen Eigenschaften und die Niederschlagseffizienz der Wolke beeinflusst. Die meisten konventionellen Modelle gehen von homogener Mischung aus; jedoch kann die Mischung auch inhomogen erfolgen. Inhomogene Mischung verändert die DSD anders als homogene Mischung und reduziert oft die Reflektivität der Wolke. Daher ist die genaue Darstellung dieser unterschiedlichen Mischungszenarien und das Verständnis ihrer Häufigkeit für die Verbesserung der Wolkenmodellgenauigkeit von entscheidender Bedeutung. Die Darstellung inhomogener Mischung ist eine Herausforderung, da ihre typische Längenskala unterhalb der Auflösung selbst fortschrittlicher Wolkenmodelle liegt. Hier verwenden wir das L3-Modell—ein neuartiges Grobstruktursimulationsmodell, das mit partikelbasierter Wolkenmikrophysik und einem subskaligen Turbulenzmodell gekoppelt ist—um das vollständige Spektrum turbulenter Mischungsskalen zu simulieren, die für inhomogene Mischung relevant sind. Mit dem L3-Modell zeigen wir, wie Entrainment und Mischung die DSD-Form auf unterschiedliche Weise verändern. Wir zeigen, dass sich die DSD-Form bei homogenen und imhomogenen Mischungsprozessen wie erwartet ändert, identifizieren aber auch ein neues Szenario, in dem die DSD-Form auf bislang unbekannte Art und Weise beeinflusst wird. Dieses Szenario tritt dann ein, wenn die DSD anfänglich breit ist. Wir fanden zudem heraus, dass die anfängliche DSD-Breite entscheidend für das Eintreten der drei Mischungsszenarien ist - ein Umstand, der in bisherigen Arbeiten nicht vollständig berücksichtigt wird. Wir zeigen außerdem, dass homogene Mischungsprozesse zwar die vorherrschenden sind, aber der Anteil inhomogener Mischungsprozesse übereinstimmend mit Beobachtungen im Laufe des Lebenszyklus flacher Kumuluswolken zunimmt. Es bleibt aber unklar, welche mikrophysikalischen und Umgebungseffekte dafür verantwortlich sind. Wir fanden heraus, dass zunehmend inhomogene Mischung mit dem Grad der Wolkenverdünnung zusammenhängt, die entweder durch den kumulativen Entrainmenteffekt oder durch eine trockenere, aerosolbeladene Umgebung beeinflusst wird. Abschließend untersuchen wir durch die Verfolgung einzelner Tropfen die DSD-Entwicklung in Stratocumulus-Wolken. Wir zeigen, dass sich die Form der DSD unterschiedlich entwickeln kann, je nachdem, ob die Tropfen stark oder schwach von Entrainment und Mischung beeinflusst sind. Dies könnte auf unterscheidliche Mischungsszenarien hindeuten, obwohl dies nicht notwendigerweise auf die Mischung selbst zurückzuführen ist, sondern eher auf großskalige Prozesse. Zusammengefasst zeigen unsere Ergebnisse, dass das L3-Modell nicht nur bestehende Theorien zum Entrainment und zur Mischung unterstützt, sondern auch bislang übersehene Komplexitäten aufdeckt und ein wertvolles Instrument für die Bearbeitung zentraler Fragen in der Wolkenmikrophysik darstellt, um unser Verständnis der Rolle von Wolken im Klimasystem voranzubringen

Life Cycle Evolution of Mixing in Shallow Cumulus Clouds

Understanding how entrainment and mixing shape the cloud droplet size distribution (DSD) is crucial for understanding the optical properties and precipitation efficiency of clouds. Different mixing scenarios, mainly homogeneous and inhomogeneous, shape the DSD in a distinct way and alter the cloud's impact on climate. However, the prevalence of these mixing scenarios and how they vary in space and time is still uncertain, as underlying processes are commonly unresolved by conventional numerical models. To overcome this challenge, we employ the L3 model, which considers supersaturation fluctuations and turbulent mixing down to the finest relevant lengthscales, making it possible to represent different mixing scenarios realistically. We investigate the spatial and temporal evolution of mixing scenarios over the life cycle of shallow cumulus clouds for varying boundary layer humidities and aerosol concentrations. Our findings suggest homogeneous mixing is generally predominant in cumulus clouds, while different mixing scenarios occur concurrently in the same cloud. Notably, inhomogeneous mixing increases over the cloud life cycle across all analyzed cases. The mean and standard deviation of supersaturation are found to be the most capable indicators of this evolution, providing a comprehensive insight into the characteristics of mixing scenarios. Finally, we show inhomogeneous mixing is more prevalent in drier boundary layers and for higher aerosol concentrations, underscoring the need for a more comprehensive investigation of how these mixing dynamics evolve in a changing climate

Between Broadening and Narrowing: How Mixing Affects the Width of the Droplet Size Distribution

Entrainment and mixing play an essential role in shaping the droplet size distribution (DSD), with commensurate effects on cloud radiative properties or precipitation formation. In this paper, we use a model that considers all relevant scales related to entrainment and mixing by employing the linear eddy model (LEM) as a subgrid-scale (SGS) mixing model, coupled with a large-eddy simulation model and a Lagrangian cloud model (LCM) for a single cumulus congestus cloud. We confirm that the DSD is broadened toward small-size droplets during homogeneous mixing. During inhomogeneous mixing, the DSD width remains almost unchanged. The DSD width can also be narrowed after mixing. We show that this happens when DSD is broadened toward small-size droplets, which evaporate rapidly, while larger droplets are almost unaffected. In addition, when droplets ascend during mixing, DSD narrowing is caused when the adiabatic increase in supersaturation is slower than the average droplet evaporation, allowing only the largest droplets to benefit from the newly produced supersaturation. The narrowing mixing scenario prevents clouds from having too broad DSDs and causes the DSD relative dispersion to converge around 0.2 to 0.4. As this scenario is more frequent when the LEM SGS model is used, our results indicate that adequately modeling turbulent mixing is necessary to represent a realistic DSD shape

Actin Cytoskeleton and Golgi Involvement in Barley stripe mosaic virus Movement and Cell Wall Localization of Triple Gene Block Proteins.

Barley stripe mosaic virus (BSMV) induces massive actin filament thickening at the infection front of infected Nicotiana benthamiana leaves. To determine the mechanisms leading to actin remodeling, fluorescent protein fusions of the BSMV triple gene block (TGB) proteins were coexpressed in cells with the actin marker DsRed: Talin. TGB ectopic expression experiments revealed that TGB3 is a major elicitor of filament thickening, that TGB2 resulted in formation of intermediate DsRed:Talin filaments, and that TGB1 alone had no obvious effects on actin filament structure. Latrunculin B (LatB) treatments retarded BSMV cell-to-cell movement, disrupted actin filament organization, and dramatically decreased the proportion of paired TGB3 foci appearing at the cell wall (CW). BSMV infection of transgenic plants tagged with GFP-KDEL exhibited membrane proliferation and vesicle formation that were especially evident around the nucleus. Similar membrane proliferation occurred in plants expressing TGB2 and/or TGB3, and DsRed: Talin fluorescence in these plants colocalized with the ER vesicles. TGB3 also associated with the Golgi apparatus and overlapped with cortical vesicles appearing at the cell periphery. Brefeldin A treatments disrupted Golgi and also altered vesicles at the CW, but failed to interfere with TGB CW localization. Our results indicate that actin cytoskeleton interactions are important in BSMV cell-to-cell movement and for CW localization of TGB3

Flow Reconstruction Using Spatially Restricted Domains Based on Enhanced Super-Resolution Generative Adversarial Networks

This study aims to reconstruct the complete flow field from spatially restricted domain data by utilizing an Enhanced Super-Resolution Generative Adversarial Network (ESRGAN) model. The difficulty in flow field reconstruction lies in accurately capturing and reconstructing large amounts of data under nonlinear, multi-scale, and complex flow while ensuring physical consistency and high computational efficiency. The ESRGAN model has a strong information mapping capability, capturing fluctuating features from local flow fields of varying geometries and sizes. The model effectiveness in reconstructing the whole domain flow field is validated by comparing instantaneous velocity fields, flow statistical properties, and probability density distributions. Using laminar bluff body flow from Direct Numerical Simulation (DNS) as a priori case, the model successfully reconstructs the complete flow field from three non-overlapping limited regions, with flow statistical properties perfectly matching the original data. Validation of the power spectrum density (PSD) for the reconstruction results also proves that the model could conform to the temporal behavior of the real complete flow field. Additionally, tests using DNS turbulent channel flow with a friction Reynolds number ($Re_\tau = 180$) demonstrate the model ability to reconstruct turbulent fields, though the quality of results depends on the number of flow features in the local regions. Finally, the model is applied to reconstruct turbulence flow fields from Particle Image Velocimetry (PIV) experimental measurements, using limited data from the near-wake region to reconstruct a larger field of view. The turbulence statistics closely match the experimental data, indicating that the model can serve as a reliable data-driven method to overcome PIV field-of-view limitations while saving computational costs.Comment: 27 pages, 16 figure

Lymphocyte-monocyte ratio at day 14 of first cisplatin-doxorubicin chemotherapy is associated with treatment outcome of pediatric patients with localized osteosarcoma

Purpose We aimed to determine the prognostic significance of lymphocyte counts and the lymphocytemonocyte ratio (LMR) in pediatric patients with osteosarcoma. Methods We retrospectively reviewed the medical records of 27 pediatric patients with localized extremity osteosarcoma, treated at the Korea Cancer Center Hospital between May 2002 and March 2016. Leukocyte counts and LMR before treatment and on day 14 (LMR14) of the first cisplatin-doxorubicin chemotherapy round were evaluated. Patients were dichotomized according to the median value of these parameters, and survival rates were compared. Results The median age of the 27 patients was 9.9 years (range, 3.2–14.1 years) and tumor sites were: distal femur (n=14), proximal humerus (n=7), proximal tibia (n=2), proximal fibula (n=2), and elsewhere (n=2). Patients were followed up on for a median of 76.4 months (range, 4.5–174.7 months), and 5-year overall (OS) and event-free survival (EFS) rates were 66.0%±9.8% and 60.9%±9.7%, respectively. Patients with a higher pretreatment lymphocyte count (≥2,320/μL) had better OS (90.9% vs. 46.2%, P=0.04) and EFS (83.9% vs. 38.5%, P=0.02). However, the day 14 lymphocyte count was not associated with survival. While no survival difference was observed between patients grouped according to pretreatment LMR (median value, 6.3), patients with a higher LMR14 (≥5) fared better than those with lower LMR14 (5-year OS: 83.3% vs. 46.3%, P=0.04). Conclusion Pretreatment lymphocyte count and LMR during chemotherapy had prognostic significance in pediatric osteosarcoma patients. Further studies involving larger cohorts are necessary to validate our findings

Structural and histological characterization of oviductal magnum and lectin-binding patterns in Gallus domesticus

<p>Abstract</p> <p>Background</p> <p>Although chicken oviduct is a useful model and target tissue for reproductive biology and transgenesis, little is known because of the highly specific hormonal regulation and the lack of fundamental researches, including lectin-binding activities and glycobiology. Because lectin is attached to secreted glycoproteins, we hypothesized that lectin could be bound to secretory egg-white proteins, and played a crucial role in the generation of egg-white protein in the oviduct. Hence, the purpose of this study was to investigate the structural, histological and lectin-binding characteristics of the chicken oviductal magnum from juvenile and adult hens.</p> <p>Methods</p> <p>The oviductal magnums from juvenile and adult hens were prepared for ultrastructural analysis, qRT-PCR and immunostaining. Immunohistochemistry of anti-ovalbumin, anti-ESR1 and anti-PGR, and mRNA expression of egg-white genes and steroid hormone receptor genes were evaluated. Lectin histochemical staining was also conducted in juvenile and adult oviductal magnum tissues.</p> <p>Results</p> <p>The ultrastructural analysis showed that ciliated cells were rarely developed on luminal surface in juvenile magnum, but not tubular gland cells. In adult magnum, two types of epithelium and three types of tubular gland cells were observed. qRT-PCR analysis showed that egg-white genes were highly expressed in adult oviduct compared with the juvenile. However, mRNA expressions of <it>ESR1 </it>and <it>PGR </it>were considerably higher in juvenile oviduct than adult (<it>P </it>< 0.05). The immunohistochemical analysis showed that anti-ovalbumin antibody was detected in adult oviduct not in juvenile, unlikely anti-ESR1 and anti-PGR antibodies that were stained in both oviducts. In histological analysis, Toluidine blue was stained in juvenile and adult oviductal epithelia, and adult tubular glands located in the outer layer of oviductal magnum. In contrast, PAS was positive only in adult oviductal tubular gland. Lectins were selectively bound to oviductal epithelium, stroma, and tubular gland cells. Particularly, lectin-ConA and WGA were bound to electron-dense secretory granules in tubular gland.</p> <p>Conclusions</p> <p>The observation of ultrastructural analysis, mRNA expression, immunohistochemistry and lectin staining showed structural and physiological characterization of juvenile and adult oviductal magnum. Consequently, oviduct study could be helped to <it>in vitro </it>culture of chicken oviductal cells, to develop epithelial or tubular gland cell-specific markers, and to understand female reproductive biology and endocrinology.</p

Orthodontic bonding procedures significantly influence biofilm composition

Background Because changes in surface properties affect bacterial adhesion, orthodontic bonding procedures may significantly influence biofilm formation and composition around orthodontic appliances. However, most studies used a mono-species biofilm model under static conditions, which does not simulate the intraoral environment and complex interactions of oral microflora because the oral cavity is a diverse and changeable environment. In this study, a multi-species biofilm model was used under dynamic culture conditions to assess the effects of the orthodontic bonding procedure on biofilm formation and compositional changes in two main oral pathogens, Streptococcus mutans and Porphyromonas gingivalis. Methods Four specimens were prepared with bovine incisors and bonding adhesive: untreated enamel surface (BI), enamel surface etched with 37% phosphoric acid (ET), primed enamel surface after etching (PR), and adhesive surface (AD). Surface roughness (SR), surface wettability (SW), and surface texture were evaluated. A multi-species biofilm was developed on each surface and adhesion amounts of Streptococcus mutans, Porphyromonas gingivalis, and total bacteria were analyzed at day 1 and day 4 using real-time polymerase chain reaction. After determining the differences in biofilm formation, SR, and SW between the four surfaces, relationships between bacteria levels and surface properties were analyzed. Results The order of SR was AD < PR < BI < ET, as BI and ET showed more irregular surface texture than PR and AD. For SW, ET had the greatest value followed by PR, BI, and AD. S. mutans and P. gingivalis showed greater adhesion to BI and ET with rougher and more wettable surfaces than to AD with smoother and less wettable surfaces. The adhesion of total bacteria and S. mutans significantly increased over time, but the amount of P. gingivalis decreased. The adhesion amounts of all bacteria were positively correlated with SR and SW, irrespective of incubation time. Conclusions Within the limitations of this study, changes in SR and SW associated with orthodontic bonding had significant effects on biofilm formation and composition of S. mutans and P. gingivalis.This work was supported by the National Research Foundation of Korea [NRF-2017R1A2B4001834]

Tuberculosis-associated hemophagocytic lymphohistiocytosis in adolescent diagnosed by polymerase chain reaction

We present a case of tuberculosis-associated hemophagocytic lymphohistiocytosis in a 14-year-old girl. The patient presented with weight loss, malaise, fatigue, prolonged fever, and generalized lymphadenopathy. Laboratory investigation revealed pancytopenia (white blood cells, 2,020 cells/µL; hemoglobin, 10.2 g/dL; platelets, 52,000 cells/µL), hypertriglyceridemia (229 mg/dL), and hyperferritinemia (1,420 ng/mL). Bone marrow biopsy showed a hypocellular bone marrow with a large numbers of histiocytes and marked hemophagocytosis; based on these findings, she was diagnosed with hemophagocytic lymphohistiocytosis. Polymerase chain reaction (PCR) with both the bone marrow aspiration and sputum samples revealed the presence of Mycobacterium tuberculosis. Antitubercular therapy with immune modulation therapy including dexamethasone and intravenous immunoglobulin was initiated. The results of all laboratory tests including bone marrow biopsy and PCR with both the bone marrow aspiration and sputum samples were normalized after treatment. Thus, early bone marrow biopsy and the use of techniques such as PCR can avoid delays in diagnosis and improve the survival rates of patients with tuberculosis-associated hemophagocytic lymphohistiocytosis