Effects of aligned PLGA/SrCSH composite scaffolds on in vitro growth and osteogenic differentiation of human mesenchymal stem cells.

Strontium (Sr) has important functions in bone remodeling. Incorporating strontium-doped α-calcium sulfate hemihydrate (SrCSH) into poly(lactic-co-glycolic acid) (PLGA) fibrous scaffolds were expected to increase its bio-activity and provide a potential material for bone tissue engineering. In the present study, Sr-containing aligned PLGA/SrCSH fibrous scaffolds similar to the architecture of natural bone were prepared via wet spinning. CCK-8 assay revealed that Sr-containing scaffolds possessed better bioactivity and supported favorable cell growth effectively. The aligned PLGA/SrCSH fibers exerted a contact effect on cell attachment, inducing regular cell alignment and influencing a series of cell behaviors. Releasing of high concentration Sr from a-PLGA/SrCSH scaffolds could induce high expression levels of BMP-2, increase ALP activity and upregulate RUNX-2 expression, and further promote the expressions of COL-I and OCN and the maximum mineralization. This study demonstrated that Sr and ordered structure in a-PLGA/SrCSH fibrous scaffolds could synergistically enhance the osteogenic differentiation of umbilical cord mesenchymal stem cells (UCMSCs) by regulating cell arrangement and expressions of osteogenic genes.

Proteomic Analysis of Staphylococcus aureus Treated with ShangKeHuangShui.

Staphylococcus aureus (SAU) stands as the prevailing pathogen in post-traumatic infections, with the emergence of antibiotic resistance presenting formidable treatment hurdles. The pressing need is to explore novel antibiotics to address this challenge. ShangKeHuangShui (SKHS), a patented traditional Chinese herbal formula, has gained widespread use in averting post-traumatic infections, but its biological effects remain incomplete understanding. This study's primary objective was to delve into the antibacterial properties, potential antibacterial compounds within SKHS, and their associated molecular targets. In vitro SKHS antibacterial assays demonstrated that the minimum inhibitory concentration (MIC) was 8.625 mg/mL and the minimum bactericide concentration (MBC) was 17.25 mg/mL. Proteomic analysis based on tandem mass tag (TMT) showed significant changes in the expression level of 246 proteins in SKHS treated group compared to control group, with 79 proteins upregulated and 167 proteins downregulated (>1.5-fold, p < 0.05). Subsequently, thirteen target proteins related to various biological processes and multiple metabolic pathways were selected to conduct parallel reaction monitoring (PRM) and molecular docking screen. In protein tyrosine phosphatase PtpA (ptpA) docking screening, phellodendrine and obacunone can bind to ptpA with the binding energy of - 8.4 and - 8.3 kcal/mol, respectively. This suggests their potential impact on antibacterial activity by modulating the two-component system of SAU. The discovery lays a groundwork for future research endeavors for exploring new antibacterial candidates and elucidating specific active chemical components within SKHS that match target proteins. Further investigations are imperative to unveil the biological effects of these monomers and their potential synergistic actions.

Liquid crystalline matrix-induced viscoelastic mechanical stimulation modulates activation and phenotypes of macrophage.

Accumulating evidence indicates that the mechanical microenvironment exerts profound influences on inflammation and immune modulation, which are likely to be key factors in successful tissue regeneration. The elastic modulus (Em) of the matrix may be a useful adjustable property to control macrophage activation and the overall inflammatory response. This study constituted a series of Em-tunable liquid crystalline cell model (HpCEs) resembling the viscoelastic characteristic of ECM and explored how mechanical microenvironment induced by liquid crystalline soft matter matrix affected macrophage activation and phenotypes. We have shown that HpCEs prepared in this work exhibited typical cholesteric liquid crystal phase and distinct viscoelastic rheological characteristics. All liquid crystalline HpCE matrices facilitated macrophages growth and maintained cell activity. Macrophages in lower-Em HpCE matrices were more likely to polarize toward the pro-inflammatory M1 phenotype. Conversely, the higher-Em HpCEs induced macrophages into an elongated shape and upregulated M2-related markers. Furthermore, the higher-Em HpCEs (HpCE-O1, HpCE-H2, HpCE-H1) could coax sequential polarization states of RAW264.7 from a classically activated "M1" state toward alternatively activated "M2" state in middle and later stage of cell culture (within 3-7 days in this work), suggesting that the HpCE-based strategies could manipulate the local immune microenvironment and promote the dominance of the pro-inflammatory signals in early stages, while M2 macrophages in later stages. The liquid crystalline soft mode fabricated in this work maybe offer a new design guideline for in vitro cell models and applications.

Structure and conformational plasticity of the U6 small nuclear ribonucleoprotein core.

U6 small nuclear RNA (snRNA) is a key component of the active site of the spliceosome, a large ribonucleoprotein complex that catalyzes the splicing of precursor messenger RNA. Prior to its incorporation into the spliceosome, U6 is bound by the protein Prp24, which facilitates unwinding of the U6 internal stem-loop (ISL) so that it can pair with U4 snRNA. A previously reported crystal structure of the `core' of the U6 small nuclear ribonucleoprotein (snRNP) contained an ISL-stabilized A62G mutant of U6 bound to all four RNA-recognition motif (RRM) domains of Prp24 [Montemayor et al. (2014), Nature Struct. Mol. Biol. 21, 544-551]. The structure revealed a novel topology containing interlocked rings of protein and RNA that was not predicted by prior biochemical and genetic data. Here, the crystal structure of the U6 snRNP core with a wild-type ISL is reported. This complex crystallized in a new space group, apparently owing in part to the presence of an intramolecular cross-link in RRM1 that was not observed in the previously reported U6-A62G structure. The structure exhibits the same protein-RNA interface and maintains the unique interlocked topology. However, the orientation of the wild-type ISL is altered relative to the A62G mutant structure, suggesting inherent structural dynamics that may facilitate its pairing with U4. Consistent with their similar architectures in the crystalline state, the wild-type and A62G variants of U6 exhibit similar Prp24-binding affinities and electrophoretic mobilities when analyzed by gel-shift assay.

Part-based visual tracking via online weighted P-N learning.

We propose a novel part-based tracking algorithm using online weighted P-N learning. An online weighted P-N learning method is implemented via considering the weight of samples during classification, which improves the performance of classifier. We apply weighted P-N learning to track a part-based target model instead of whole target. In doing so, object is segmented into fragments and parts of them are selected as local feature blocks (LFBs). Then, the weighted P-N learning is employed to train classifier for each local feature block (LFB). Each LFB is tracked through the corresponding classifier, respectively. According to the tracking results of LFBs, object can be then located. During tracking process, to solve the issues of occlusion or pose change, we use a substitute strategy to dynamically update the set of LFB, which makes our tracker robust. Experimental results demonstrate that the proposed method outperforms the state-of-the-art trackers.