Scaffolding Role Research Articles

The Role of Scaffolds in Tendon Tissue Engineering.

Tendons are unique forms of connective tissue aiming to transmit the mechanical force of muscle contraction to the bones. Tendon injury may be due to direct trauma or might be secondary to overuse injury and age-related degeneration, leading to inflammation, weakening and subsequent rupture. Current traditional treatment strategies focus on pain relief, reduction of the inflammation and functional restoration. Tendon repair surgery can be performed in people with tendon injuries to restore the tendon’s function, with re-rupture being the main potential complication. Novel therapeutic approaches that address the underlying pathology of the disease is warranted. Scaffolds represent a promising solution to the challenges associated with tendon tissue engineering. The ideal scaffold for tendon tissue engineering needs to exhibit physiologically relevant mechanical properties and to facilitate functional graft integration by promoting the regeneration of the native tissue.

X- and Y-Linked Chromatin-Modifying Genes as Regulators of Sex-Specific Cancer Incidence and Prognosis

Biological sex profoundly conditions organismal development and physiology, imposing wide-ranging effects on cell signaling, metabolism, and immune response. These effects arise from sex-specified differences in hormonal exposure, and from intrinsic genetic and epigenetic differences associated with the presence of an XX versus XY chromosomal complement. In addition, biological sex is now recognized to be a determinant of the incidence, presentation, and therapeutic response of multiple forms of cancer, including cancers not specifically associated with male or female anatomy. Although multiple factors contribute to sex-based differences in cancer, a growing body of research emphasizes a role for differential activity of X- and Y-linked tumor-suppressor genes in males and females. Among these, the X-linked KDM6A/UTX and KDM5C/JARID1C/SMCX, and their Y-linked paralogs UTY/KDM6C and KDM5D/JARID1D/SMCY encode lysine demethylases. These epigenetic modulators profoundly influence gene expression, based on enzymatic activity in demethylating H3K27me3 and H3K4me3, and nonenzymatic scaffolding roles for large complexes that open and close chromatin for transcription. In a growing number of cases, mutations affecting these proteins have been recognized to strongly influence cancer risk, prognosis, and response to specific therapies. However, sex-specific patterns of mutation, expression, and activity of these genes, coupled with tissue-specific requirement for their function as tumor suppressors, together exemplify the complex relationship between sex and cancer vulnerabilities. In this review, we summarize and discuss the current state of the literature on the roles of these proteins in contributing to sex bias in cancer, and the status of clinical agents relevant to their function.

Recent Advances in Porous 3D Cellulose Aerogels for Tissue Engineering Applications: A Review

Current approaches in developing porous 3D scaffolds face various challenges, such as failure of mimicking extracellular matrix (ECM) native building blocks, non-sustainable scaffold fabrication techniques, and lack of functionality. Polysaccharides and proteins are sustainable, inexpensive, biodegradable, and biocompatible, with structural similarities to the ECM. As a result, 3D-structured cellulose (e.g., cellulose nanofibrils, nanocrystals and bacterial nanocellulose)-based aerogels with high porosity and interconnected pores are ideal materials for biomedical applications. Such 3D scaffolds can be prepared using a green, scalable, and cost-effective freeze-drying technique. The physicochemical, mechanical, and biological characteristics of the cellulose can be improved by incorporation of proteins and other polysaccharides. This review will focus on recent developments related to the cellulose-based 3D aerogels prepared by sustainable freeze-drying methods for tissue engineering applications. We will also provide an overview of the scaffold development criteria; parameters that influenced the aerogel production by freeze-drying; and in vitro and in vivo studies of the cellulose-based porous 3D aerogel scaffolds. These efforts could potentially help to expand the role of cellulose-based 3D scaffolds as next-generation biomaterials.

Dental stem cells: The role of biomaterials and scaffolds in developing novel therapeutic strategies

Dental stem cells (DSCs) are self-renewable cells that can be obtained easily from dental tissues, and are a desirable source of autologous stem cells. The use of DSCs for stem cell transplantation therapeutic approaches is attractive due to their simple isolation, high plasticity, immunomodulatory properties, and multipotential abilities. Using appropriate scaffolds loaded with favorable biomolecules, such as growth factors, and cytokines, can improve the proliferation, differentiation, migration, and functional capacity of DSCs and can optimize the cellular morphology to build tissue constructs for specific purposes. An enormous variety of scaffolds have been used for tissue engineering with DSCs. Of these, the scaffolds that particularly mimic tissue-specific micromilieu and loaded with biomolecules favorably regulate angiogenesis, cell-matrix interactions, degradation of extracellular matrix, organized matrix formation, and the mineralization abilities of DSCs in both in vitro and in vivo conditions. DSCs represent a promising cell source for tissue engineering, especially for tooth, bone, and neural tissue restoration. The purpose of the present review is to summarize the current developments in the major scaffolding approaches as crucial guidelines for tissue engineering using DSCs and compare their effects in tissue and organ regeneration.

THE ROLE OF SCAFFOLDING IN THE DECONSTRUCTING OF THINKING STRUCTURE: A CASE STUDY OF PSEUDO-THINKING PROCESS

This study aimed to (1) analyze the role of scaffolding in deconstructing pseudo-thinking structure, and (2) analyze the development of students' thinking structures after receiving scaffolding. The study was framed with a qualitative methodology by involving case study design. This research was conducted at State Junior High School 31 in Semarang City, Indonesia. Data was collected through tests, observation, and interview methods. Result of the study indicated that (1) scaffolding has changed the pseudo thinking process into a real thought process, and (2) scaffolding could develop students’ thinking structure into a more complex (abstract) level. Their thinking structure was initially on the stage of comparative thinking structure before receiving scaffolding assistance and after receiving scaffolding, to developed into the stage of logical reasoning thinking structure. In other words, scaffolding could become a useful strategy to help students go through different Zone of Proximal Development (ZPD).

The Role of Scaffolding in Nature School to Promote Sustainable Development in Education

The Role of Scaffolding in Nature School to Promote Sustainable Development in Education

Improving hydrogen sorption performances of MgH2 through nanoconfinement in a mesoporous CoS nano-boxes scaffold

For the first time, structure-modified CoS-nanoboxes (CoS-NBs) scaffold as a multifunctional Supporting material has been developed by using a template-consumption method for nanoconfinement of MgH2 particles within its mesoporous structure (denoted as MgH2@CoS-NBs). Microstructural observations via transmission electron microscopy (TEM) reveal the uniform distribution of MgH2 nanocrystals within the mesoporous networks of CoS-NBs scaffold and the surface decoration of MgH2 crystals by in-situ formed MgS phase. The peculiar core-shell structured morphology of MgH2 nanocrystals and the “nano-size effect” notably enhances the thermodynamic properties of MgH2 through the reduction in hydriding and dehydriding enthalpies (−65.6 ± 1.1 and 68.1 ± 1.4 kJ mol−1 H2, respectively). Moreover, the improved hydrogen sorption kinetics can be attributed to the catalytic effect of MgS through reducing the intrinsic kinetic energy barriers for both hydriding and dehydriding (57.4 ± 2.2 and 120.8 ± 3.2 kJ mol−1 H2, respectively). The “nano-size effect” of nanoconfined Mg/MgH2 crystals, the catalyzing effect of MgS and the multifunctional role of CoS-NBs scaffold are likely to be synergistically contributed to the superior hydrogen sorption performances of MgH2@CoS-NBs composite, as compared to the pure MgH2.

Biomaterials as Local Niches for Immunomodulation.

A major function of the immune system is to detect threat from foreign invaders, tissue damage, or cancer and to mount a counter response that resolves the threat, restores homeostasis, and supplies immunological memory to prevent a second assault. Our increasing understanding of the immune system has opened up numerous avenues for modulating immune responses against infections, cancer, and autoimmunity. However, agents used for immunomodulation have been traditionally administered systemically via bolus injection, leading to unintended consequences by disrupting homeostasis at nontarget sites. Consequently, systemic hyperactivation and hypoactivation can result from bolus administration of immune-activators and immunosuppressants, respectively. Macroscale biomaterial scaffolds can instead be placed at the intended target site to provide both localized, controlled release of immunomodulatory agents and control over local immune cell trafficking and function, potentially maximizing therapeutic efficacy and limiting systemic exposure. These scaffolds have found utility in the area of cancer immunotherapy, especially in situ cancer vaccination where controlled release of factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and the local presentation of tumor antigen and danger signals lead to the recruitment of immature dendritic cells and facilitate their activation and antigen presentation. These cells eventually migrate into secondary lymphoid organs where they prime tumor specific T cells for downstream tumor clearance. Scaffolds can also be used in adoptive T cell therapy to generate large numbers of potent antigen specific T cells or chimeric antigen receptor (CAR) T cells in vitro for subsequent delivery to patients. Macroscale biomaterial scaffolds have also found utility beyond cancer immunotherapy and have been developed to promote immune tolerance by regulatory T cell induction and to expedite tissue regeneration. The design of these macroscale biomaterial scaffolds considers their biocompatibility, biodegradability, mode of delivery, porosity, and kinetics of therapeutic cargo release. Consequently, the numerous approaches that have been developed to fabricate biomaterial scaffolds are aimed at tuning these parameters to achieve the desired therapeutic outcome. This Account will discuss the use of biomaterial scaffolds as niches for immunomodulation and will focus on (1) approaches that have been used to fabricate various biomaterial systems being employed as niches for immunomodulation and (2) how these biomaterial systems have been used to modulate immune responses, specifically in area of cancer immunotherapy, where we will discuss the role of macroscale biomaterial scaffolds for in situ vaccination and in vitro T cell expansion. We will also briefly discuss the utility of biomaterial scaffolds beyond cancer, drawing examples from tolerance and tissue regeneration.

Abstract 5222: Degraders targeting both IRAK4 and IMiD substrates show combinatorial effects leading to broader activity with durable and complete regressions in MYD88 mutant lymphoma xenografts in vivo

Abstract Targeted protein degraders (TPD) are heterobifunctional small molecules that employ the ubiquitin degradation system to drive the selective degradation of target proteins. In approximately one third of B-cell lymphomas, gain of function mutations in MYD88 constitutively activate the myddosome and drive proliferation and survival through NFkB and AP1 signaling. IRAK4, is a key component of the myddosome and IRAK4 TPD show potent and selective IRAK4 degradation and preferential activity in MYD88 mutated B cell lymphoma models. Notably, the activity of IRAK4 degraders is superior to kinase inhibition, supporting the essential scaffolding role of IRAK4 in Myddosome signaling. An important goal of cancer therapy is to drive to deep and durable responses in patients, and this is frequently achieved by combination therapy. It has been suggested that blocking NFkB while simultaneously inducing a Type 1 IFN response with an IMiD (e.g. Lenalidomide Yang et al. (2012) Cancer Cell 21, 6, p723) may drive additive or synergistic antitumor activity. We have developed novel degraders that utilize an IMiD as a cereblon binder. These compounds simultaneously degrade both IRAK4 and IMiD substrates, enabling a therapeutically-relevant biological combination within a single small molecule. Here we show that dual IRAK4 and IMiD based degraders have potent antiproliferative activity across MYD88 mutant, but not MYD88WT lymphoma cell lines, with increased and broader antiproliferative and apoptosis activity relative to selective IRAK4 degraders or IMiDs alone. Several lines of evidence suggest that both IRAK4 and IMiD activity contribute to the overall superior activity of the dual degraders. Proteomic analysis demonstrates degradation of both both IRAK4 and key IMiD substrates, including Ikaros and Ailolos. This activity results in an enhanced Type 1 IFN response signature compared to selective IRAK4 degraders or IMiD alone, suggesting cooperative biological activity. Degradation of both IRAK4 and IMiD substrates corelates with cell activity, consistent with a requirement for both activities to drive cell death. In xenograft models of MYD88 mutant DLBCL, daily oral dosing of lead dual - degraders demonstrates strong antitumor activity in xenograft models of MYD88 mutant lymphoma, including durable complete regressions that can be maintained for several weeks following cessation of dosing. Regressions are associated with degradation of both IRAK4 and IMiD substrates, consistent with the dual-targeting activity of these molecules. Collectively, these data support a strategy to combine IRAK4 degradation and IMiD activity in a single molecule that will have the potential benefits of enhanced therapeutic activity, increased convenience and decreased potential for drug combination challenges, such as DDI. Lead degraders based on this synergistic profile are being advanced towards IND in 2020. Citation Format: Duncan H. Walker, Michele Mayo, Christine Klaus, Haojing Rong, Scott Rusin, Kirti Sharma, Alice McDonald, Veronica Campbell, Joseph Kelleher, Jared Gollob, Nello Mainolfi, Matt Weiss. Degraders targeting both IRAK4 and IMiD substrates show combinatorial effects leading to broader activity with durable and complete regressions in MYD88 mutant lymphoma xenografts in vivo [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5222.

Growth Factor and Its Polymer Scaffold-Based Delivery System for Cartilage Tissue Engineering.

The development of biomaterials, stem cells and bioactive factors has led to cartilage tissue engineering becoming a promising tactic to repair cartilage defects. Various polymer three-dimensional scaffolds that provide an extracellular matrix (ECM) mimicking environment play an important role in promoting cartilage regeneration. In addition, numerous growth factors have been found in the regenerative process. However, it has been elucidated that the uncontrolled delivery of these factors cannot fully exert regenerative potential and can also elicit undesired side effects. Considering the complexity of the ECM, neither scaffolds nor growth factors can independently obtain successful outcomes in cartilage tissue engineering. Therefore, collectively, an appropriate combination of growth factors and scaffolds have great potential to promote cartilage repair effectively; this approach has become an area of considerable interest in recent investigations. Of late, an increasing trend was observed in cartilage tissue engineering towards this combination to develop a controlled delivery system that provides adequate physical support for neo-cartilage formation and also enables spatiotemporally delivery of growth factors to precisely and fully exert their chondrogenic potential. This review will discuss the role of polymer scaffolds and various growth factors involved in cartilage tissue engineering. Several growth factor delivery strategies based on the polymer scaffolds will also be discussed, with examples from recent studies highlighting the importance of spatiotemporal strategies for the controlled delivery of single or multiple growth factors in cartilage tissue engineering applications.

Recent Advances in Pyridine‐Based Organocatalysis and its Application towards Valuable Chemical Transformations

AbstractThe role of pyridine scaffolds in the field of synthetic organic and medicinal chemistry is impeccable and irreplaceable due to its wide spectrum of applications. Pyridines are well known for their usage as bases and to some extent they have been employed as ligands. In recent times, pyridine scaffolds are explored as organocatalysts to accomplish various novel chemical transformations. Here in this review, we have focused on highlighting the protocols available to accomplish wide range of chemical modulations employing different pyridine moieties as organocatalysts for various reactions such as reductive borylation, acylation, heterocyclization and additions to carbonyl derivatives. The application of organocatalysis in the fields of kinetic resolution and desymmetrization are also been presented

Two Sides of Electrospun Fiber in Promoting and Inhibiting Biomedical Processes

AbstractElectrospinning is a versatile technique for generating ultrathin fibers, which is widely applied in various biomedical applications. The properties and structures of the fibers are specifically engineered to meet the needs of particular applications. The impact of nanofibrous scaffolds on biological processes is related to the promotion or inhibition of specific cell or bioactive substance functions. Here, a novel analysis of the diverse roles of electrospun nanofibrous scaffolds is provided and recent advances in exploiting their binary attributes for applications in biomedicine are summarized. This review initially introduces the development techniques for electrospinning, specifically the engineering of electrospun nanofibers. Then, scaffold applications for cell migration, adhesion, proliferation, and accelerating regeneration in cardiac, nerve, skeletal muscle, bone tissue, and wound healing are presented. Moreover, their inhibitory properties in cancer treatments, antibacterial applications, anti‐adhesion, anti‐scarring, and inhibition of thrombus formation are summarized. Eventually, the potential for future work using multifunctional, electrospun, nanofibrous scaffolds, in order to further inspire the development of scaffolds for biomedical treatments is summarized and discussed.

How Abstract (Non-embodied) Linguistic Representations Augment Cognitive Control.

Recent scholarship emphasizes the scaffolding role of language for cognition. Language, it is claimed, is a cognition-enhancing niche (Clark, 2006), a programming tool for cognition (Lupyan and Bergen, 2016), even neuroenhancement (Dove, 2019) and augments cognitive functions such as memory, categorization, cognitive control, and meta-cognitive abilities (“thinking about thinking”). Yet, the notion that language enhances or augments cognition, and in particular, cognitive control does not easily fit in with embodied approaches to language processing, or so we will argue. Accounts aiming to explain how language enhances various cognitive functions often employ a notion of abstract representation. Yet, embodied approaches to language processing have it that language processing crucially, according to some accounts even exclusively, involves embodied, modality-specific, i.e., non-abstract representations. In coming to understand a particular phrase or sentence, a prior experience has to be simulated or reenacted. The representation thus activated is embodied (modality-specific) as sensorimotor regions of the brain are thereby recruited. In this paper, we will first discuss the notion of representation, clarify what it takes for a representation to be embodied or abstract, and distinguish between conceptual and (other) linguistic representations. We will then put forward a characterization of cognitive control and examine its representational infrastructure. The remainder of the paper will be devoted to arguing that language augments cognitive control. To that end, we will draw on two lines of research, which investigate how language augments cognitive control: (i) research on the availability of linguistic labels and (ii) research on the active usage of a linguistic code, specifically, in inner speech. Eventually, we will argue that the cognition-enhancing capacity of language can be explained once we assume that it provides us with (a) abstract, non-embodied representations and with (b) abstract, sparse linguistic representations that may serve as easy-to-manipulate placeholders for fully embodied or otherwise more detailed representations.

14-3-3ζ mediates an alternative, non-thermogenic mechanism in male mice to reduce heat loss and improve cold tolerance

ObjectiveAdaptive thermogenesis, which is partly mediated by sympathetic input on brown adipose tissue (BAT), is a mechanism of heat production that confers protection against prolonged cold exposure. Various endogenous stimuli, for example, norepinephrine and FGF-21, can also promote the conversion of inguinal white adipocytes to beige adipocytes, which may represent a secondary cell type that contributes to adaptive thermogenesis. We previously identified an essential role of the molecular scaffold 14-3-3ζ in adipogenesis, but one of the earliest, identified functions of 14-3-3ζ is its regulatory effects on the activity of tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of norepinephrine. Herein, we examined whether 14-3-3ζ could influence adaptive thermogenesis via actions on BAT activation or the beiging of white adipocytes. MethodsTransgenic mice over-expressing a TAP-tagged human 14-3-3ζ molecule or heterozygous mice without one allele of Ywhaz, the gene encoding 14-3-3ζ, were used to explore the contribution of 14-3-3ζ to acute (3 h) and prolonged (3 days) cold (4 °C) exposure. Metabolic caging experiments, PET-CT imaging, and laser Doppler imaging were used to determine the effect of 14-3-3ζ over-expression on thermogenic and vasoconstrictive mechanisms in response to cold. ResultsTransgenic over-expression of 14-3-3ζ (TAP) in male mice significantly improved tolerance to acute and prolonged cold. In response to cold, body temperatures in TAP mice did not decrease to the same extent when compared to wildtype (WT) mice, and this was associated with increased UCP1 expression in beige inguinal white tissue (iWAT) and BAT. Of note was the paradoxical finding that cold-induced changes in body temperatures of TAP mice were associated with significantly decreased energy expenditure. The marked improvements in tolerance to prolonged cold were not due to changes in sensitivity to β-adrenergic stimulation or BAT or iWAT oxidative metabolism; instead, over-expression of 14-3-3ζ significantly decreased thermal conductance and heat loss in mice via increased peripheral vasoconstriction. ConclusionsDespite being associated with elevations in cold-induced UCP1 expression in brown or beige adipocytes, these findings suggest that 14-3-3ζ regulates an alternative, non-thermogenic mechanism via vasoconstriction to minimize heat loss during cold exposure.

Plectin dysfunction in neurons leads to tau accumulation on microtubules affecting neuritogenesis, organelle trafficking, pain sensitivity and memory.

AimsPlectin, a universally expressed multi‐functional cytolinker protein, is crucial for intermediate filament networking, including crosstalk with actomyosin and microtubules. In addition to its involvement in a number of diseases affecting skin, skeletal muscle, heart, and other stress‐exposed tissues, indications for a neuropathological role of plectin have emerged. Having identified P1c as the major isoform expressed in neural tissues in previous studies, our aim for the present work was to investigate whether, and by which mechanism(s), the targeted deletion of this isoform affects neuritogenesis and proper nerve cell functioning.MethodsFor ex vivo phenotyping, we used dorsal root ganglion and hippocampal neurons derived from isoform P1c‐deficient and plectin‐null mice, complemented by in vitro experiments using purified proteins and cell fractions. To assess the physiological significance of the phenotypic alterations observed in P1c‐deficient neurons, P1c‐deficient and wild‐type littermate mice were subjected to standard behavioural tests.ResultsWe demonstrate that P1c affects axonal microtubule dynamics by isoform‐specific interaction with tubulin. P1c deficiency in neurons leads to altered dynamics of microtubules and excessive association with tau protein, affecting neuritogenesis, neurite branching, growth cone morphology, and translocation and directionality of movement of vesicles and mitochondria. On the organismal level, we found P1c deficiency manifesting as impaired pain sensitivity, diminished learning capabilities and reduced long‐term memory of mice.ConclusionsRevealing a regulatory role of plectin scaffolds in microtubule‐dependent nerve cell functions, our results have potential implications for cytoskeleton‐related neuropathies.

The Role of Collagen Scaffold and Stromal Vascular Fraction on Healing Process in Growth Plate Injury (SOX9 and Histological Examination)

BACKGROUND: Pediatric skeletal trauma presents a distinct approach to its treatment because of its unique auses and possibility of its troublesome complications. One of its major complications is growth plate injury which may disturb the longitudinal growth of child’s bone.
 AIM: In this study, the author combined stromal vascular fraction (SVF) and collagen scaffold as biomaterial for future treatment of physeal injury in skeletally immature patients using SOX9 and histological examination as a marker.
 METHODS: The study was conducted experimentally on Rattus norvegicus growth plate based on Erickson study, and the SVF was from R. norvegicus fat tissue with ZUK method. Histological examination was evaluated with 8 times magnification and SOX9 from the growth plate was measured with enzyme-linked immunosorbent assay.
 RESULTS: Histological examination showed that the best result was obtained in SVF + collagen group judging by the bony bridge diameter. The result was differed significantly from the positive control group with p < 0.05 in Tukey test. The result from SOX9 level measurement shows that all of the treatment groups SOX9 level almost the same as normal value (negative control group) and it is significantly differ from the positive control group with p < 0.05 in Mann–Whitney U-test.
 CONCLUSIONS: This study showed that the combination of collagen and SVF had a great effect on healing process in growth plate injury.

Impact of a Healing Garden on Self-Consciousness in Patients with Advanced Alzheimer’s Disease: An Exploratory Study1

The environment of patients with Alzheimer's disease and related disorders (ADRD) intensifies the consequences of cognitive impairment and exacerbates behavioral problems if inappropriate or, conversely, mitigate these problems if its design is tailored to the needs of these persons. We evaluate the impacts of hospitalization and of a specific healing garden on self-consciousness which represent a central impairment in ADRD. The self-consciousness questionnaire (SCQ), validated for its assessment at mild to moderate phases of the disease, explores the dimensions of personal identity, awareness of cognitive deficiencies, self-assessment of affective state, awareness of body representation, prospective memory, capacity for introspection, and moral judgments. After having verified, by means of a preliminary study, its feasibility to the more advanced stages of the disease, this questionnaire allowed assessment of the impact of the environment by comparing, in routine care, patients hospitalized in a cognitive-behavioral unit who solely remain indoors with others who use the Art, Memory and Life healing garden. A significant decrease in SCQ due to an increase in anosognosia during hospitalization was observed in the group that remained indoors. For the group using the garden, a positive effect on overall SCQ score was observed, as a result of a significant improvement in body representation as the driving parameter. Factors that are grounded in the hypotheses that spearheaded its conception, such as sensory enrichment, familiarity, contact with nature, scaffolding role for cognitive functions, supportive effect for social interactions, and the "Nancy hypotheses of beauty", thus contribute to their validation.

Effectiveness of Scaffolding Strategies in Learning Against Decrease in Mathematics Anxiety Level

This study is a mixture of quantitative and qualitative with sequential explanatory designs. The study aims to (1) analyze the improvement of student achievement in learning after scaffolding, (2) evaluate the level of students 'mathematics anxiety, and (3) describe the role of scaffolding in changing students' perceptions of mathematics anxiety in classroom learning. Sampling through random sampling techniques obtained by students of class X-IPA-1 and X-IPA-2 in SMA Negeri 6 Semarang. Quantitative data analysis uses statistical test techniques: normality test, paired sample t-test, and N-gain test. Qualitative data analysis through interactive methods namely data collection, data reduction, data presentation, and drawing conclusions. Data validation techniques through the source and method triangulation. The results showed that (1) there was an increase in student learning achievement after the application of the scaffolding strategy by 33.0% to 34.5%; (2) there was a decrease in the level of mathematics anxiety in students by 90.4%; (3) through scaffolding, students succeed in reflecting and correcting mistakes in solving previous problems. This means scaffolding can be an effective strategy to help students move across different Zones of Proximal Development (ZPD). The scaffolding strategy has also created a positive classroom environment that encourages students to learn mathematics without fear.

Crystal structure and interactions of the Tof1-Csm3 (Timeless-Tipin) fork protection complex.

The Tof1–Csm3 fork protection complex has a central role in the replisome—it promotes the progression of DNA replication forks and protects them when they stall, while also enabling cohesion establishment and checkpoint responses. Here, I present the crystal structure of the Tof1–Csm3 complex from Chaetomium thermophilum at 3.1 Å resolution. The structure reveals that both proteins together form an extended alpha helical repeat structure, which suggests a mechanical or scaffolding role for the complex. Expanding on this idea, I characterize a DNA interacting region and a cancer-associated Mrc1 binding site. This study provides the molecular basis for understanding the functions of the Tof1–Csm3 complex, its human orthologue the Timeless–Tipin complex and additionally the Drosophila circadian rhythm protein Timeless.

A helical assembly of human ESCRT-I scaffolds reverse-topology membrane scission.

The ESCRT complexes drive membrane scission in HIV-1 release, autophagosome closure, MVB biogenesis, cytokinesis, and other cell processes. ESCRT-I is the most upstream complex and bridges the system to HIV-1 Gag in virus release. The crystal structure of the headpiece of human ESCRT-I comprising TSG101–VPS28–VPS37B–MVB12A was determined, revealing an ESCRT-I helical assembly with a 12 molecule repeat. Electron microscopy confirmed that ESCRT-I subcomplexes form helical filaments in solution. Mutation of VPS28 helical interface residues blocks filament formation in vitro and autophagosome closure and HIV-1 release in human cells. Coarse grained simulations of ESCRT assembly at HIV-1 budding sites suggest that formation of a 12-membered ring of ESCRT-I molecules is a geometry-dependent checkpoint during late stages of Gag assembly and HIV-1 budding, and templates ESCRT-III assembly for membrane scission. These data show that ESCRT-I is not merely a bridging adaptor, but has an essential scaffolding and mechanical role in its own right.