Transforming growth factor-ß1-loaded RADA-16 hydrogel scaffold for effective cartilage regeneration.

Cartilage repair remains a major challenge in clinical trials. These current cartilage repair materials can not effectively promote chondrocyte generation, limiting their practical application in cartilage repair. In this work, we develop an implantable scaffold of RADA-16 peptide hydrogel incorporated with TGF-ß1 to provide a microenvironment for stem cell-directed differentiation and chondrocyte adhesion growth. The longest release of growth factor TGF-ß1 release can reach up to 600 h under physiological conditions. TGF-ß1/RADA-16 hydrogel was demonstrated to be a lamellar porous structure. Based on the cell culture with hBMSCs, TGF-ß1/RADA-16 hydrogel showed excellent ability to promote cell proliferation, directed differentiation into chondrocytes, and functional protein secretion. Within 14 days, 80% of hBMSCs were observed to be directed to differentiate into vigorous chondrocytes in the co-culture of TGF-ß1/RADA-16 hydrogels with hBMSCs. Specifically, these newly generated chondrocytes can secrete and accumulate large amounts of collagen II within 28 days, which can effectively promote the formation of cartilage tissue. Finally, the exploration of RADA-16 hydrogel-based scaffolds incorporated with TGF-ß1 bioactive species would further greatly promote the practical clinical trials of cartilage remediation, which might have excellent potential to promote cartilage regeneration in areas of cartilage damage.

What makes an article a must read in medical education?

BACKGROUND: The dissemination of published scholarship is intended to bring new evidence and ideas to a wide audience. However, the increasing number of articles makes it challenging to determine where to focus one's attention. This study describes factors that may influence decisions to read and recommend a medical education article. METHODS: Authors analyzed data collected from March 2021 through September 2022 during a monthly process to identify "Must Read" articles in medical education. An international team of health sciences educators, learners, and researchers voted on titles and abstracts to advance articles to full text review. Full texts were rated using five criteria: relevance, methodology, readability, originality, and whether it addressed a critical issue in medical education. At an end-of-month meeting, 3-4 articles were chosen by consensus as "Must Read" articles. Analyses were used to explore the associations of article characteristics and ratings with Must Read selection. RESULTS: Over a period of 19 months, 7487 articles from 856 journals were screened, 207 (2.8%) full texts were evaluated, and 62 (0.8%) were chosen as Must Reads. During screening, 3976 articles (53.1%) received no votes. BMC Medical Education had the largest number of articles at screening (n = 1181, 15.8%). Academic Medicine had the largest number as Must Reads (n = 22, 35.5%). In logistic regressions adjusting for the effect of individual reviewers, all rating criteria were independently associated with selection as a Must Read (p < 0.05), with methodology (OR 1.44 (95%CI = 1.23-1.69) and relevance (OR 1.43 (95%CI = 1.20-1.70)) having the highest odds ratios. CONCLUSIONS: Over half of the published medical education articles did not appeal to a diverse group of potential readers; this represents a missed opportunity to make an impact and potentially wasted effort. Our findings suggest opportunities to enhance value in the production and dissemination of medical education scholarship.

Protamine folds DNA into flowers and loop stacks.

DNA in sperm undergoes an extreme compaction to almost crystalline packing levels. To produce this dense packing, DNA is dramatically reorganized in minutes by protamine proteins. Protamines are positively charged proteins that coat negatively charged DNA and fold it into a series of toroids. The exact mechanism for forming these ∼50-kbp toroids is unknown. Our goal is to study toroid formation by starting at the "bottom" with folding of short lengths of DNA that form loops and working "up" to more folded structures that occur on longer length scales. We previously measured folding of 200-300 bp of DNA into a loop. Here, we look at folding of intermediate DNA lengths (L = 639-3003 bp) that are 2-10 loops long. We observe two folded structures besides loops that we hypothesize are early intermediates in the toroid formation pathway. At low protamine concentrations (∼0.2 µM), we see that the DNA folds into flowers (structures with multiple loops that are positioned so they look like the petals of a flower). Folding at these concentrations condenses the DNA to 25% of its original length, takes seconds, and is made up of many small bending steps. At higher protamine concentrations (≥2 µM), we observe a second folded structure-the loop stack-where loops are stacked vertically one on top of another. These results lead us to propose a two-step process for folding at this length scale: 1) protamine binds to DNA, bending it into loops and flowers, and 2) flowers collapse into loop stacks. These results highlight how protamine uses a bind-and-bend mechanism to rapidly fold DNA, which may be why protamine can fold the entire sperm genome in minutes.

Creating de novo peptide-based bioactivities: from assembly to origami.

DNA origami has created complex structures of various spatial dimensions. However, their versatility in terms of function is limited due to the lower number of the intrinsic building blocks, i.e. nucleotides, compared with the number of amino acids. Therefore, protein origami has been proposed and demonstrated to precisely fabricate artificial functional nanostructures. Despite their hierarchical folded structures, chain-like peptides and DNA share obvious similarities in both structures and properties, especially in terms of chain hybridization; therefore, replacing DNA with peptides to create bioactivities not only has high theoretical feasibility but also provides a new bottom-up synthetic strategy. However, designing functionalities with tens to hundreds of peptide chains using the similar principle of DNA origami has not been reported, although the origami strategy holds great potential to generate more complex bioactivities. In this perspective review, we have reviewed the recent progress in and highlighted the advantages of peptide assembly and origami on the orientation of artificially created bioactivities. With the great potential of peptide origami, we appeal to develop user-friendly softwares in combination with artificial intelligence.

Protamine loops DNA in multiple steps.

Protamine proteins dramatically condense DNA in sperm to almost crystalline packing levels. Here, we measure the first step in the in vitro pathway, the folding of DNA into a single loop. Current models for DNA loop formation are one-step, all-or-nothing models with a looped state and an unlooped state. However, when we use a Tethered Particle Motion (TPM) assay to measure the dynamic, real-time looping of DNA by protamine, we observe the presence of multiple folded states that are long-lived (∼100 s) and reversible. In addition, we measure folding on DNA molecules that are too short to form loops. This suggests that protamine is using a multi-step process to loop the DNA rather than a one-step process. To visualize the DNA structures, we used an Atomic Force Microscopy (AFM) assay. We see that some folded DNA molecules are loops with a ∼10-nm radius and some of the folded molecules are partial loops-c-shapes or s-shapes-that have a radius of curvature of ∼10 nm. Further analysis of these structures suggest that protamine is bending the DNA to achieve this curvature rather than increasing the flexibility of the DNA. We therefore conclude that protamine loops DNA in multiple steps, bending it into a loop.

Modulation of foreign body reaction and macrophage phenotypes concerning microenvironment.

The foreign body reaction (FBR) is described as a local chronic inflammation after implantation of biomaterials in which macrophages involved intimately. At the stage of acute inflammation, mast cells release histamine, Interleukin-4 (IL-4) and Interleukin-13 (IL-13), enhancing recruitment, and fusion of macrophages in the following phase. As for chronic intensive inflammation, degradation of biomaterials would be promoted by macrophage-derived foreign body giant cells releasing degradative enzymes, acid and reactive oxygen intermediates. Nevertheless, it could be seen as a breakthrough point for regulating FBR, considering the dominant role of the macrophage in the immune response as exemplified by the decrease of IL-4 and IL-13, stabilizing an appropriate balance between two macrophage phenotypes, selectively suppressing some function of macrophages, and so on. Moreover, the relationship between macrophages polarization and the development of a fibrous capsule, which increase the possibility of implantation failure, will be illustrated later. This review aims at providing readers a comprehensive understanding of FBR and its correlative treatment strategy.

Molecular mechanism of crolibulin in complex with tubulin provides a rationale for drug design.

Microtubules (MTs) is one of the most important proteins in eukaryotic cells and plays a key role in the maintenance of cell morphology and cell division. The discovery and development of small molecule drugs targeting MTs has always been an important direction of anti-cancer research. Nowadays 4-Aryl-4H-chromenes have emerged as potent microtubule-targeting agents (MTAs) for various cancers. Crolibulin, a derivative of 4-Aryl-4H-chromenes, which has been progressed to Phase I/II clinical testing's for anaplastic thyroid cancer with the National Cancer Institute. However, the design and development of 4-Aryl-4H-chromenes family drugs have been hindered for a long time by the lack of structural information of the tubulin-agent complex. Here we report a 2.5 Šcrystal structure of tubulin complexed with crolibulin. This complex structure reveals the interactions between crolibulin and tubulin, helps explain the results of the structure-activity-relationship (SAR) studies and provides a solid structural basis for the design and development of new 4-Aryl-4H-chromenes derivatives as MTAs.

Genome Sequence of Corynebacterium pseudotuberculosis Strain KM01, Isolated from the Abscess of a Goat in Kunming, China.

Caseous lymphadenitis (CLA) is an acute, pyogenic, and contagious disease of goat that imposes considerable economic losses for farmers, and it is caused by Corynebacterium pseudotuberculosis Herein, we introduce the genome sequencing of C. pseudotuberculosis strain KM01, isolated from an abscess of a Saanen goat from Kunming, China. The genome contains 2,198 genes, the total length of the genes was 2,337,666 bp, and the GC content was 52.18%. The number of tandem repeat sequences was 44, the total length of the tandem repeat sequences was 1,970 bp (0.0772% of the genome), the number of minisatellite DNAs was 36, and there were 48 tRNAs and 12 rRNAs.

Fluorescence resonance energy transfer between bovine serum albumin and fluoresceinamine.

Physical binding-mediated organic dye direct-labelling of proteins could be a promising technology for bio-nanomedical applications. Upon binding, it was found that fluorescence resonance energy transfer (FRET) occurred between donor bovine serum albumin (BSA; an amphiphilic protein) and acceptor fluoresceinamine (FA; a hydrophobic fluorophore), which could explain fluorescence quenching found for BSA. FRET efficiency and the distance between FA and BSA tryptophan residues were determined to 17% and 2.29 nm, respectively. Using a spectroscopic superimposition method, the saturated number of FAs that bound to BSA was determined as eight to give a complex formula of FA8-BSA. Finally, molecular docking between BSA and FA was conducted, and conformational change that occurred in BSA upon binding to FA molecules was also studied by three-dimensional fluorescence microscopy.

Understanding the Robust Physisorption between Bovine Serum Albumin and Amphiphilic Polymer Coated Nanoparticles.

The robust physisorption between nanoparticles (NPs) and proteins has attracted increasing attention due to the significance for both conjugation techniques and protein's corona formation at the bionano interface. In the present study, we first explored the possible binding sites of the bovine serum albumin (BSA) on amphiphilic polymer coated gold nanoparticles (AP-AuNPs). By using mass spectrometry, a 105-amino-acid peptide (12.2 kDa) is discovered as the possible "epitope" responsible for the robust physisorption between BSA and AP-AuNPs. Second, with the help of nanometal surface energy transfer (NSET) theory, we further found that the epitope peptide could insert at least 2.9 nm into the organic molecular layers of AP-AuNPs when the robust conjugates formed, which indicates how such a long epitope peptide can be accommodated by AP-AuNPs and resist protease's digestion. These findings might shed light on a new strategy for studying interactions between proteins and NPs, and further guide the rational design of NPs for safe and effective biomedical applications.