Current status of vitamin D2 deficiency among children in a region of China.

Background: The aim of this study was to explore the current status of vitamin D2 (VD2) deficiency in hospitalized children in a region of China. Methods: The instances of detection of vitamin D (VD) and VD2 in children who visited the hospital from January 2022 to May 2023 were analyzed retrospectively. Additionally, the relationships between VD2 level and gender and age were further analyzed. Furthermore, for departments with a high frequency of VD detection, the VD2 deficiencies in children with different diseases were further analyzed. Results: Among the different age groups, children aged 11-15 years exhibited the most severe VD2 deficiency, followed by those aged 7-10 years, 0-1 years, and 2-6 years. Moreover, 25(OH)D2 levels were significantly lower in children aged 7-10 years and 11-15 years compared with 2-6 years. Gender did not have an impact on the level of 25(OH)D2. When analyzing the orthopedics, dermatology, thoracic surgery, and nephroimmunology departments' data on children's levels of 25(OH)D2, it was found that an average of approximately 76.56% had levels below <1.5 ng/ml compared to individuals with levels between >15 ng/ml and 100 ng/ml. The average ratio between individuals with <1.5 ng/ml vs. those with <15 ng/ml was found to be 91.22%. Conclusions: Children who came to the hospital were severely deficient in VD2. The degree of deficiency was related to age, but there was no gender difference. The phenomenon of VD2 deficiency was reflected in children with both skeletal and non-skeletal diseases.

Leveling up Organic Semiconductors with Crystal Twisting.

The performance of crystalline organic semiconductors depends on the solid-state structure, especially the orientation of the conjugated components with respect to device platforms. Often, crystals can be engineered by modifying chromophore substituents through synthesis. Meanwhile, dissymetry is necessary for high-tech applications like chiral sensing, optical telecommunications, and data storage. The synthesis of dissymmetric molecules is a labor-intensive exercise that might be undermined because common processing methods offer little control over orientation. Crystal twisting has emerged as a generalizable method for processing organic semiconductors and offers unique advantages, such as patterning of physical and chemical properties and chirality that arises from mesoscale twisting. The precession of crystal orientations can enrich performance because achiral molecules in achiral space groups suddenly become candidates for the aforementioned technologies that require dissymetry.

Self-Patterning Tetrathiafulvalene Crystalline Films.

Tetrathiafulvalene (TTF) crystals grown from the melt are organized as spherulites in which helicoidal fibrils growing radially from the nucleation center twist in concert with one another. Alternating bright and dark concentric bands are apparent when films are viewed between crossed polarizers, indicating an alternating pattern of crystallographic faces exposed at the film surface. Band-dependent reorganization of the TTF crystals was observed during exposure to methanol vapor. Crystalline growth appears on bright bands at the expense of the dark bands. After a 24 h period of exposure to methanol vapor, the original spherulites were completely restructured, and the films comprise isolated, concentric circles of crystallites whose orientations are determined by the initial TTF crystal fibril orientation. While the surface of these outgrowths appears faceted and smooth, cross-sectional SEM images revealed a semiporous inner structure, suggesting solvent-vapor-induced recrystallization. Collectively, these results show that crystal twisting can be used to rhythmically redistribute material. Crystal twisting is a common and often controllable phenomenon independent of molecular or crystal structure and therefore offers a generalizable path to spontaneous pattern formation in a wide range of materials.

Collimating the growth of twisted crystals of achiral compounds.

A great proportion of molecular crystals can be made to grow as twisted fibrils. Typically, this requires high crystallization driving forces that lead to spherulitic textures. Here, it is shown how micron size channels fabricated from poly(dimethylsiloxane) (PDMS) serve to collimate the circular polycrystalline growth fronts of optically banded spherulites of twisted crystals of three compounds, coumarin, 2,5-bis(3-dodecyl-2-thienyl)-thiazolo[5,4-d]thiazole, and tetrathiafulvalene. The relationships between helicoidal pitch, growth front coherence, and channel width are measured. As channels spill into open spaces, collimated crystals "diffract" via small angle branching. On the other hand, crystals grown together from separate channels whose bands are out of phase ultimately become a single in-phase bundle of fibrils by a cooperative mechanism yet unknown. The isolation of a single twist sense in individual channels is described. We forecast that such chiral molecular crystalline channels may function as chiral optical wave guides.

Illusory spirals and loops in crystal growth.

The theory of dislocation-controlled crystal growth identifies a continuous spiral step with an emergent lattice displacement on a crystal surface; a mechanistic corollary is that closely spaced, oppositely winding spirals merge to form concentric loops. In situ atomic force microscopy of step propagation on pathological L-cystine crystals did indeed show spirals and islands with step heights of one lattice displacement. We show by analysis of the rates of growth of smaller steps only one molecule high that the major morphological spirals and loops are actually consequences of the bunching of the smaller steps. The morphology of the bunched steps actually inverts the predictions of the theory: Spirals arise from pairs of dislocations, loops from single dislocations. Only through numerical simulation of the growth is it revealed how normal growth of anisotropic layers of molecules within the highly symmetrical crystals can conspire to create features in apparent violation of the classic theory.

Crystal growth inhibitors for the prevention of L-cystine kidney stones through molecular design.

Crystallization of L-cystine is a critical step in the pathogenesis of cystine kidney stones. Treatments for this disease are somewhat effective but often lead to adverse side effects. Real-time in situ atomic force microscopy (AFM) reveals that L-cystine dimethylester (L-CDME) and L-cystine methylester (L-CME) dramatically reduce the growth velocity of the six symmetry-equivalent {100} steps because of specific binding at the crystal surface, which frustrates the attachment of L-cystine molecules. L-CDME and L-CME produce l-cystine crystals with different habits that reveal distinct binding modes at the crystal surfaces. The AFM observations are mirrored by reduced crystal yield and crystal size in the presence of L-CDME and L-CME, collectively suggesting a new pathway to the prevention of L-cystine stones by rational design of crystal growth inhibitors.

Attachment of calcium oxalate monohydrate crystals on patterned surfaces of proteins and lipid bilayers.

The attachment of calcium oxalate monohydrate (COM) crystals to renal tubules is thought to be one of the critical steps of kidney stone formation. Patterns of phosphatidylserine (DPPS) bilayers and osteopontin (OPN) were fabricated on silica substrates through the combination of a microcontact printing technique and fusion of lipid vesicles to create spatially organized surfaces of lipids and proteins that may mimic renal tubule surfaces while allowing direct visualization of the competition for COM attachment to compositionally different regions. In the case of DPPS-OPN patterns, micrometer-sized COM crystals dispersed in saturated aqueous calcium oxalate solutions attached preferentially to the OPN regions, in agreement with other in vitro studies that have suggested a binding affinity of OPN to COM crystal surfaces. COM crystals attached with nearly equal coverage to OPN and DPPS surfaces alone, suggesting that the preferential segregation of COM crystals to the OPN regions on the patterned surfaces reflects reversible attachment of micrometer-sized COM crystals capable of Brownian motion. These attached microcrystals then grow larger over time during immersion in the supersaturated calcium oxalate solutions. Free OPN, a major constituent in urine, adsorbs on COM crystals and suppresses attachment to DPPS, suggesting a link between OPN and reduced attachment of COM crystals to renal epithelium. This patterning protocol can be expanded to other urinary molecules, providing a convenient approach for understanding the effects of biomolecules on COM crystal attachment and the pathogenesis of kidney stones.

Suberoylanilide hydroxamic acid limits migration and invasion of glioma cells in two and three dimensional culture.

High grade gliomas are aggressive cancers that are not well addressed by current chemotherapies, in large measure because these drugs do not curtail the diffuse invasion of glioma cells into brain tissue surrounding the tumor. Here, we investigate the effects of suberoylanilide hydroxamic acid (SAHA) on glioma cells in 2D and 3D in vitro assays, as SAHA has previously been shown to significantly increase apoptosis, decrease proliferation, and interfere with migration in other cell lines. We find that SAHA has significant independent effects on proliferation, migration, and invasion. These effects are seen in both 2D and 3D culture. In 3D culture, with glioma spheroids embedded in collagen I matrices, SAHA independently limits both glioma invasion and the reorganization of the tumor surroundings that usually proceeds such invasion. The decreased matrix reorganization and invasion is not accompanied by decreased production or activity of matrix-metalloproteases but instead may be related to increased cell-cell adhesion.

Polyelectrolyte microcapsule interactions with cells in two- and three-dimensional culture.

Microcapsules fabricated by layer-by-layer self-assembly have unique physicochemical properties that make them attractive for drug delivery applications. This study chiefly investigated the biocompatibility of one of the most stable types of microcapsules, those composed of poly-(sodium 4-styrene sulfonate) [PSS] and poly-(allylamine hydrochloride) [PAH], with cells cultured on two-dimensional (2D) substrates and in three-dimensional (3D) matrices. C6 glioma and 3T3 fibroblast cell morphology was observed after 24h of co-culture with PSS/PAH microcapsules on a 2D substrate. Cells were also cultured with four other types of microcapsules, each composed of at least one naturally occurring polyelectrolyte. At microcapsule to cell ratios up to 100:1, it was found that PSS/PAH microcapsules do not affect number of viable cells more substantially than do the other microcapsules investigated. However, differences in number of viable cells were found as a function of microcapsule composition, and our results suggest particular biochemical interactions between cells and internalized microcapsules, rather than mechanical effects, are responsible for these differences. We then investigated the effects of PSS/PAH microcapsules on cells embedded in 3D collagen matrices, which more closely approximate the tumor environments in which microcapsules may be useful drug delivery agents. Matrix structure, cell invasion, and volumetric spheroid growth were investigated, and we show that these microcapsules have a negligible effect on cell invasion and tumor spheroid growth even at high concentration. Taken together, this work suggests that PSS/PAH microcapsules have sufficiently high biocompatibility with at least some cell lines for use as proof of principle drug delivery agents in in vitro studies.

pH controlled permeability of lipid/protein biomimetic microcapsules.

The permeability of lipid and protein microcapsules fabricated by alternating adsorption of human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) on a template and subsequent removal of the core is studied as a function of pH value and supplementary layers. The capsules were permeable for macromolecules (FITC-labeled dextran, M(w) 40 kDa) at pH < 4.8 and impermeable at pH > 7.4. The assembly of supplementary DMPA bilayers rendered the capsules impermeable for small hydrophilic molecules such as 6-carboxyfluorescein (6-CF). Hence DMPA/HSA capsules can be resealed after fabrication by supplementary layers. This provides the opportunity of applying such biomimetic membrane capsules as drug carriers or model systems to study biological processes at membranes.

Molecular assembly of biomimetic microcapsules.

Our recent work on the fabrication of microcapsules comprised of human serum albumin (HSA) and -α-dimyristoylphosphatitic acid (DMPA) by means of stepwise adsorption of HSA and DMPA on fluid droplet surfaces or charged colloids and subsequent dissolution of the cores is reviewed. The lipid self-assembles as a bilayer on the protein surface and the completed microcapsule serves as a biomimetic membrane model. The DMPA/HSA microcapsules have good biocompatibility and the potential for the insertion of recognition units in the lipid bilayers. The structure and properties of the lipid/protein microcapsules are described and their potential for applications in sustained drug release are introduced.

Self-assembly of human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) microcapsules for controlled drug release.

Human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) were applied as a pair to encapsulate ibuprofen microcrystals by means of a technique based on the layer-by-layer (LbL) assembly of oppositely charged species, for the purpose of controlling drug release. The successful adsorption of HSA and DMPA multilayers onto ibuprofen crystals was confirmed by optical microscopy. The drug release process, in a solution of pH 7.4, was monitored by optical microscopy and UV spectroscopy. The results revealed that the rate of release of ibuprofen from HSA/DMPA microcapsules decreased as the capsule wall thickness and drug crystal size increased, indicating that the permeability of the microcapsules can be controlled by simply varying the number of HSA/DMPA deposition cycles.

Biogenic capsules made of proteins and lipids.

Multilayer biogenic capsules with a micrometer scale were fabricated by self-assembly of proteins and lipids at the interface of emulsion droplets. The optical microscopy images demonstrate that spherical capsules at a fluid interface have uniform walls and the dried capsules possess a high mechanical strength. The hollow shells obtained provide a novel class of assembly with encapsulating drug molecules based on the layer-by-layer technique.