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1.
ACS Macro Lett ; 13(5): 571-576, 2024 May 21.
Article in English | MEDLINE | ID: mdl-38647178

ABSTRACT

Controlling the access of proteases to cleavable peptides placed at specific locations within macromolecular architectures represents a powerful strategy for biologically responsive materials design. Here, we report the synthesis of peptide-containing bivalent bottlebrush (co)polymers (BBPs) featuring polyethylene glycol (PEG) and 7-amino-4-methylcoumarin (AMC) pendants on each backbone repeat unit. The AMCs are linked via caspase-3-cleavable peptides which, upon enzymatic cleavage, provide a "turn-on" fluorescence signal due to the release of free AMC. Time-dependent fluorscence measurements demonstrate that the caspase-3-induced peptide cleavage and AMC release from BBPs is strongly dependent on the BBP backbone length and the AMC-peptide linker location within the BBP architecture, revealing fundamental insights into the interactions of enzymes with BBPs.


Subject(s)
Caspase 3 , Fluorescent Dyes , Polyethylene Glycols , Fluorescent Dyes/chemistry , Caspase 3/metabolism , Polyethylene Glycols/chemistry , Coumarins/chemistry , Peptides/chemistry , Peptides/metabolism , Polymers/chemistry , Humans
2.
Elife ; 132024 Apr 15.
Article in English | MEDLINE | ID: mdl-38619110

ABSTRACT

A productive HIV-1 infection in humans is often established by transmission and propagation of a single transmitted/founder (T/F) virus, which then evolves into a complex mixture of variants during the lifetime of infection. An effective HIV-1 vaccine should elicit broad immune responses in order to block the entry of diverse T/F viruses. Currently, no such vaccine exists. An in-depth study of escape variants emerging under host immune pressure during very early stages of infection might provide insights into such a HIV-1 vaccine design. Here, in a rare longitudinal study involving HIV-1 infected individuals just days after infection in the absence of antiretroviral therapy, we discovered a remarkable genetic shift that resulted in near complete disappearance of the original T/F virus and appearance of a variant with H173Y mutation in the variable V2 domain of the HIV-1 envelope protein. This coincided with the disappearance of the first wave of strictly H173-specific antibodies and emergence of a second wave of Y173-specific antibodies with increased breadth. Structural analyses indicated conformational dynamism of the envelope protein which likely allowed selection of escape variants with a conformational switch in the V2 domain from an α-helix (H173) to a ß-strand (Y173) and induction of broadly reactive antibody responses. This differential breadth due to a single mutational change was also recapitulated in a mouse model. Rationally designed combinatorial libraries containing 54 conformational variants of V2 domain around position 173 further demonstrated increased breadth of antibody responses elicited to diverse HIV-1 envelope proteins. These results offer new insights into designing broadly effective HIV-1 vaccines.


Subject(s)
AIDS Vaccines , Dermatitis , HIV-1 , Animals , Mice , Humans , HIV-1/genetics , Antibody Formation , Longitudinal Studies , AIDS Vaccines/genetics , Antibodies , Antigens, Viral
3.
Chem Commun (Camb) ; 60(31): 4238-4241, 2024 Apr 11.
Article in English | MEDLINE | ID: mdl-38529790

ABSTRACT

Polymer-protein bioconjugation offers a powerful strategy to alter the physical properties of proteins, and various synthetic polymer compositions and architectures have been investigated for this purpose. Nevertheless, conjugation of molecular bottlebrush polymers (BPs) to proteins remains an unsolved challenge due to the large size of BPs and a general lack of methods to transform the chain ends of BPs into functional groups suitable for bioconjugation. Here, we present a strategy to address this challenge in the context of BPs prepared by "graft-through" ring-opening metathesis polymerization (ROMP), one of the most powerful methods for BP synthesis. Quenching ROMP of PEGylated norbornene macromonomers with an activated enyne terminator facilitates the transformation of the BP Ru alkylidene chain ends into Pd oxidative addition complexes (OACs) for facile bioconjugation. This strategy is shown to be effective for the synthesis of two BP-protein conjugates (albumin and ERG), setting the stage for a new class of BP-protein conjugates for future therapeutic and imaging applications.


Subject(s)
Polymers , Proteins , Polymerization , Albumins
4.
Osteoarthr Cartil Open ; 6(1): 100428, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38229918

ABSTRACT

Objective: As part of the first phase of the OARSI Early-stage Symptomatic Knee Osteoarthritis (EsSKOA) initiative, we explored the first symptoms and experiences recalled by individuals with knee osteoarthritis (OA). Design: This qualitative study, informed by qualitative description, was a secondary analysis of focus groups (n â€‹= â€‹17 groups) and one-on-one interviews (n â€‹= â€‹3) conducted in 91 individuals living with knee OA as part of an international study to better understand the OA pain experience. In each focus group or interview, participants were asked to describe their first symptoms of knee OA. We inductively coded these transcripts and conducted thematic analysis. Results: Mean age of participants was 70 years (range 47-92) and 68 â€‹% were female. We developed four overarching themes: Insidious and Episodic Onset, Diverse Early Symptoms, Must be Something Else, and Adjustments. Participants described the gradual and intermittent way in which symptoms of knee OA developed over many years; many could not identify a specific starting point. Participants described diverse initial knee symptoms, including activity-exacerbated joint pain, stiffness and crepitus. Most participants dismissed early symptoms or rationalized their presence, employing various strategies to enable continued participation in recreational and daily activities. Few sought medical attention until physical functioning was demonstrably impacted. Conclusions: The earliest symptoms of knee OA are frequently insidious in onset, episodic and present long before individuals present to health professionals. These results highlight challenges to identifying people with knee OA early and support the development of specific classification criteria for EsSKOA to capture individuals at an early stage.

5.
Cureus ; 15(10): e47606, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37886653

ABSTRACT

BACKGROUND: The degree of liver impairment in children with dengue infection varies from mild to severe injury. Aminotransferase levels may be useful in predicting severe dengue. This study aimed to evaluate the degree of liver impairment and determine whether elevated aminotransferases could be used to discriminate between non-severe and severe dengue in Vietnamese children. METHODS: This was a prospective cohort study of pediatric patients with confirmed dengue infection who were admitted to Can Tho Children's Hospital, Vietnam. The receiver operating characteristic (ROC) curve was used to discriminate the power of Aspartate transaminase (AST) or Alanine transaminase (ALT) to predict severe dengue. RESULTS: Two hundred and thirty confirmed dengue patients were enrolled, including 70% (161) patients with non-severe dengue and 30% (69) with severe dengue. This study indicates that 73.9% of patients had abnormal AST (>40 U/L), and 34.8% of patients had abnormal ALT (>40 U/L). The incidence of dengue patients with hepatitis (AST or ALT ≥ 4×ULN) and severe hepatitis (AST or ALT ≥ 10×ULN) were 18.7% and 17.0%, respectively. At a cut-off point of 120 U/L, AST's AUROC, sensitivity, and specificity were 0.93 (95% CI: 0.90-0.96), 82.5%, and 87.3%, respectively. At a cut-off point of 80 U/L, ALT's AUROC, sensitivity, and specificity were 0.89 (95% CI: 0.84-0,93), 87.5%, and 85.2%, respectively, for predicting severe dengue. CONCLUSION: Elevated aminotransferase levels were associated with severe dengue, and AST/ALT were good markers for predicting severe dengue in Vietnamese children.

7.
JCI Insight ; 8(9)2023 05 08.
Article in English | MEDLINE | ID: mdl-37154156

ABSTRACT

The RV144 phase III vaccine trial demonstrated that ALVAC-HIV and AIDSVAX B/E administration over 6 months resulted in 31% efficacy in preventing HIV acquisition, while administration of AIDSVAX B/E alone in both VAX003 and VAX004 studies failed to show efficacy. In this study, we aimed to understand the impact of ALVAC-HIV on the development of cellular, humoral, and functional immune responses compared to the administration of AIDSVAX B/E alone. ALVAC-HIV in combination with 3 doses of AIDSVAX B/E significantly increased CD4+ HIV-specific T cell responses, polyfunctionality, and proliferation compared with 3 doses of AIDSVAX B/E alone. Additionally, Env-specific plasmablasts and A244-specific memory B cells were identified with a significantly higher magnitude in the group that received ALVAC-HIV. Subsequently, data revealed increased magnitude of plasma IgG binding to and avidity for HIV Env in participants who received ALVAC-HIV compared with 3 doses of AIDSVAX B/E alone. Lastly, levels of the Fc-mediated effector functions antibody-dependent cellular cytotoxicity, NK cell activation, and trogocytosis were significantly increased in participants who received ALVAC-HIV compared with those receiving AIDSVAX B/E alone. Taken together, these results suggest that ALVAC-HIV plays an essential role in developing cellular and humoral immune responses to protein-boosted regimens relative to protein alone.


Subject(s)
HIV Infections , HIV-1 , Humans , HIV Infections/prevention & control , HIV Antibodies , Vaccination , Immunity, Humoral
8.
Sci Adv ; 9(16): eadg2239, 2023 04 21.
Article in English | MEDLINE | ID: mdl-37075115

ABSTRACT

Imidazoquinolines (IMDs), such as resiquimod (R848), are of great interest as potential cancer immunotherapies because of their ability to activate Toll-like receptor 7 (TLR7) and/or TLR8 on innate immune cells. Nevertheless, intravenous administration of IMDs causes severe immune-related toxicities, and attempts to improve their tissue-selective exposure while minimizing acute systemic inflammation have proven difficult. Here, using a library of R848 "bottlebrush prodrugs" (BPDs) that differ only by their R848 release kinetics, we explore how the timing of R848 exposure affects immune stimulation in vitro and in vivo. These studies led to the discovery of R848-BPDs that exhibit optimal activation kinetics to achieve potent stimulation of myeloid cells in tumors and substantial reductions in tumor growth following systemic administration in mouse syngeneic tumor models without any observable systemic toxicity. These results suggest that release kinetics can be tuned at the molecular level to provide safe yet effective systemically administered immunostimulant prodrugs for next-generation cancer immunotherapies.


Subject(s)
Neoplasms , Prodrugs , Mice , Animals , Prodrugs/pharmacology , Toll-Like Receptor 7/agonists , Kinetics , Adjuvants, Immunologic/pharmacology , Neoplasms/drug therapy
9.
NPJ Vaccines ; 8(1): 43, 2023 Mar 18.
Article in English | MEDLINE | ID: mdl-36934088

ABSTRACT

This study demonstrates the impact of adjuvant on the development of T follicular helper (Tfh) and B cells, and their influence on antibody responses in mice vaccinated with SARS-CoV-2-spike-ferritin-nanoparticle (SpFN) adjuvanted with either Army Liposome Formulation containing QS-21 (SpFN + ALFQ) or Alhydrogel® (SpFN + AH). SpFN + ALFQ increased the size and frequency of germinal center (GC) B cells in the vaccine-draining lymph nodes and increased the frequency of antigen-specific naive B cells. A single vaccination with SpFN + ALFQ resulted in a higher frequency of IL-21-producing-spike-specific Tfh and GC B cells in the draining lymph nodes and spleen, S-2P protein-specific IgM and IgG antibodies, and elicitation of robust cross-neutralizing antibodies against SARS-CoV-2 variants as early as day 7, which was enhanced by a second vaccination. This was associated with the generation of high titer, high avidity binding antibodies. The third vaccination with SpFN + ALFQ elicited high levels of neutralizing antibodies against the Omicron variant. No cross-neutralizing antibodies against Omicron were induced with SpFN + AH. These findings highlight the importance of ALFQ in orchestrating early induction of antigen-specific Tfh and GC B cell responses and long-lived plasma cells in the bone marrow. The early engagement of S-2P specific naive B cells and high titer IgM antibodies shape the development of long-term neutralization breadth.

11.
J Virol ; 97(2): e0163522, 2023 02 28.
Article in English | MEDLINE | ID: mdl-36749076

ABSTRACT

Understanding the dynamics of early immune responses to HIV-1 infection, including the evolution of initial neutralizing and antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies, will inform HIV vaccine design. In this study, we assess the development of autologous neutralizing antibodies (ANAbs) against founder envelopes (Envs) from 18 participants with HIV-1 CRF01_AE acute infection. The timing of ANAb development directly associated with the magnitude of the longitudinal ANAb response. Participants that developed ANAbs within 6 months of infection had significantly higher ANAb responses at 1 year (50% inhibitory concentration [IC50] geometric mean titer [GMT] = 2,010 versus 184; P = 0.001) and 2 years (GMT = 3,479 versus 340; P = 0.015), compared to participants that developed ANAb responses after 6 months. Participants with later development of ANAb tended to develop an earlier, potent heterologous tier 1 (92TH023) neutralizing antibody (NAb) response (P = 0.049). CRF01_AE founder Env V1V2 loop lengths correlated indirectly with the timing (P = 0.002, r = -0.675) and directly with magnitude (P = 0.005, r = 0.635) of ANAb responses; Envs with longer V1V2 loop lengths elicited earlier and more potent ANAb responses. While ANAb responses did not associate with viral load, the viral load set point correlated directly with neutralization of the heterologous 92TH023 strain (P = 0.007, r = 0.638). In contrast, a striking inverse correlation was observed between viral load set point and peak ADCC against heterologous 92TH023 Env strain (P = 0.0005, r = -0.738). These data indicate that specific antibody functions can be differentially related to viral load set point and may affect HIV-1 pathogenesis. Exploiting Env properties, such as V1V2 length, could facilitate development of subtype-specific vaccines that elicit more effective immune responses and improved protection. IMPORTANCE Development of an effective HIV-1 vaccine will be facilitated by better understanding the dynamics between the founder virus and the early humoral responses. Variations between subtypes may influence the evolution of immune responses and should be considered as we strive to understand these dynamics. In this study, autologous founder envelope neutralization and heterologous functional humoral responses were evaluated after acute infection by HIV-1 CRF01_AE, a subtype that has not been thoroughly characterized. The evolution of these humoral responses was assessed in relation to envelope characteristics, magnitude of elicited immune responses, and viral load. Understanding immune parameters in natural infection will improve our understanding of protective responses and aid in the development of immunogens that elicit protective functional antibodies. Advancing our knowledge of correlates of positive clinical outcomes should lead to the design of more efficacious vaccines.


Subject(s)
Antibodies, Neutralizing , Antibody Formation , HIV Antibodies , HIV Infections , env Gene Products, Human Immunodeficiency Virus , Humans , env Gene Products, Human Immunodeficiency Virus/genetics , env Gene Products, Human Immunodeficiency Virus/immunology , HIV Infections/immunology , HIV-1
12.
Nat Nanotechnol ; 18(2): 184-192, 2023 02.
Article in English | MEDLINE | ID: mdl-36702954

ABSTRACT

Cancer therapies often have narrow therapeutic indexes and involve potentially suboptimal combinations due to the dissimilar physical properties of drug molecules. Nanomedicine platforms could address these challenges, but it remains unclear whether synergistic free-drug ratios translate to nanocarriers and whether nanocarriers with multiple drugs outperform mixtures of single-drug nanocarriers at the same dose. Here we report a bottlebrush prodrug (BPD) platform designed to answer these questions in the context of multiple myeloma therapy. We show that proteasome inhibitor (bortezomib)-based BPD monotherapy slows tumour progression in vivo and that mixtures of bortezomib, pomalidomide and dexamethasone BPDs exhibit in vitro synergistic, additive or antagonistic patterns distinct from their corresponding free-drug counterparts. BPDs carrying a statistical mixture of three drugs in a synergistic ratio outperform the free-drug combination at the same ratio as well as a mixture of single-drug BPDs in the same ratio. Our results address unanswered questions in the field of nanomedicine, offering design principles for combination nanomedicines and strategies for improving current front-line monotherapies and combination therapies for multiple myeloma.


Subject(s)
Multiple Myeloma , Prodrugs , Humans , Multiple Myeloma/drug therapy , Multiple Myeloma/pathology , Bortezomib/therapeutic use , Dexamethasone/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/pharmacology
13.
Cells ; 13(1)2023 12 22.
Article in English | MEDLINE | ID: mdl-38201237

ABSTRACT

Developing a preventative vaccine for HIV-1 has been a global priority. The elicitation of broadly neutralizing antibodies (bNAbs) against a broad range of HIV-1 envelopes (Envs) from various strains appears to be a critical requirement for an efficacious HIV-1 vaccine. To understand their ability to neutralize HIV-1, it is important to characterize the binding characteristics of bNAbs. Our work is the first to utilize microscale thermophoresis (MST), a rapid, economical, and flexible in-solution temperature gradient method to quantitatively determine the binding affinities of bNAbs and non-neutralizing monoclonal antibodies (mAbs) to HIV-1 recombinant envelope monomer and trimer proteins of different subtypes, pseudoviruses (PVs), infectious molecular clones (IMCs), and cells expressing the trimer. Our results demonstrate that the binding affinities were subtype-dependent. The bNAbs exhibited a higher affinity to IMCs compared to PVs and recombinant proteins. The bNAbs and mAbs bound with high affinity to native-like gp160 trimers expressed on the surface of CEM cells compared to soluble recombinant proteins. Interesting differences were seen with V2-specific mAbs. Although they recognize linear epitopes, one of the antibodies also bound to the Envs on PVs, IMCs, and a recombinant trimer protein, suggesting that the epitope was not occluded. The identification of epitopes on the envelope surface that can bind to high affinity mAbs could be useful for designing HIV-1 vaccines and for down-selecting vaccine candidates that can induce high affinity antibodies to the HIV-1 envelope in their native conformation.


Subject(s)
AIDS Vaccines , Communicable Diseases , HIV Seropositivity , HIV-1 , Humans , Broadly Neutralizing Antibodies , Antibodies, Monoclonal , Clone Cells , Epitopes , Recombinant Proteins , Glycoproteins , HIV Envelope Protein gp160
14.
Public Adm Dev ; 2022 Sep 23.
Article in English | MEDLINE | ID: mdl-36248011

ABSTRACT

How people make initial and collective sense under crises remains unanswered. This paper addresses this question using the control of COVID-19 in Vietnam as a case study. Our results suggest that sensemaking under crises is influenced by an institutional propensity for prevention that has developed gradually over time. Local governments play a vital role in fostering collective sensemaking which enables concerted actions in epidemic control. However, biases are inherent in sensemaking, including a delay in access to vaccine and a violation of privacy. For policy makers, this study suggests that developing specific prevention policies and programs, building large-scale coordination capacity, and promoting local initiatives are necessary for coping with epidemics. For theory development, the study explores how institutions condition sensemaking and specifies several mechanisms in which local authorities could facilitate collective sensemaking in crises.

15.
J Am Chem Soc ; 144(51): 23332-23339, 2022 12 28.
Article in English | MEDLINE | ID: mdl-36126328

ABSTRACT

Polymer conjugation has been widely used to improve the stability and pharmacokinetics of therapeutic biomacromolecules; however, conventional methods to generate such conjugates often use disperse and/or achiral polymers with limited functionality. The heterogeneity of such conjugates may lead to manufacturing variability, poorly controlled biological performance, and limited ability to optimize structure-property relationships. Here, using insulin as a model therapeutic polypeptide, we introduce a strategy for the synthesis of polymer-protein conjugates based on discrete, chiral polymers synthesized through iterative exponential growth (IEG). These conjugates eliminate manufacturing variables originating from polymer dispersity and poorly controlled absolute configuration. Moreover, they offer tunable molecular features, such as conformational rigidity, that can be modulated to impact protein function, enabling faster or longer-lasting blood glucose responses in diabetic mice when compared to PEGylated insulin and the commercial insulin variant Lantus. Furthermore, IEG-insulin conjugates showed no signs of decreased activity, immunogenicity, or toxicity following repeat dosing. This work represents a significant step toward the synthesis of precise synthetic polymer-biopolymer conjugates and reveals that fine tuning of synthetic polymer structure may be used to optimize such conjugates in the future.


Subject(s)
Diabetes Mellitus, Experimental , Polymers , Animals , Mice , Polymers/chemistry , Diabetes Mellitus, Experimental/drug therapy , Proteins/chemistry
16.
Viruses ; 14(7)2022 06 28.
Article in English | MEDLINE | ID: mdl-35891387

ABSTRACT

Pathogen-associated molecular patterns, including cytoplasmic DNA and double-strand (ds)RNA trigger the induction of interferon (IFN) and antiviral states protecting cells and organisms from pathogens. Here we discovered that the transfection of human airway cell lines or non-transformed fibroblasts with 24mer dsRNA mimicking the cellular micro-RNA (miR)29b-1* gives strong anti-viral effects against human adenovirus type 5 (AdV-C5), influenza A virus X31 (H3N2), and SARS-CoV-2. These anti-viral effects required blunt-end complementary RNA strands and were not elicited by corresponding single-strand RNAs. dsRNA miR-29b-1* but not randomized miR-29b-1* mimics induced IFN-stimulated gene expression, and downregulated cell adhesion and cell cycle genes, as indicated by transcriptomics and IFN-I responsive Mx1-promoter activity assays. The inhibition of AdV-C5 infection with miR-29b-1* mimic depended on the IFN-alpha receptor 2 (IFNAR2) and the RNA-helicase retinoic acid-inducible gene I (RIG-I) but not cytoplasmic RNA sensors MDA5 and ZNFX1 or MyD88/TRIF adaptors. The antiviral effects of miR29b-1* were independent of a central AUAU-motif inducing dsRNA bending, as mimics with disrupted AUAU-motif were anti-viral in normal but not RIG-I knock-out (KO) or IFNAR2-KO cells. The screening of a library of scrambled short dsRNA sequences identified also anti-viral mimics functioning independently of RIG-I and IFNAR2, thus exemplifying the diverse anti-viral mechanisms of short blunt-end dsRNAs.


Subject(s)
COVID-19 , Interferon Type I , MicroRNAs , Antiviral Agents/pharmacology , DEAD Box Protein 58/genetics , DEAD Box Protein 58/metabolism , DEAD-box RNA Helicases/genetics , Humans , Influenza A Virus, H3N2 Subtype/genetics , Interferon Type I/genetics , RNA, Double-Stranded , SARS-CoV-2
17.
Integr Environ Assess Manag ; 18(6): 1564-1577, 2022 Nov.
Article in English | MEDLINE | ID: mdl-35429140

ABSTRACT

According to the latest projections of the Intergovernmental Panel on Climate Change, at the end of the century, coastal zones and low-lying ecosystems will be increasingly threatened by rising global mean sea levels. In order to support integrated coastal zone management and advance the basic "source-pathway-receptor-consequence" approach focused on traditional receptors (e.g., population, infrastructure, and economy), a novel risk framework is proposed able to evaluate potential risks of loss or degradation of ecosystem services (ESs) due to projected extreme sea level scenarios in the Italian coast. Three risk scenarios for the reference period (1969-2010) and future time frame up to 2050 under RCP4.5 and RCP8.5 are developed by integrating extreme water-level projections related to changing climate conditions, with vulnerability information about the topography, distance from coastlines, and presence of artificial protections. A risk assessment is then performed considering the potential effects of the spatial-temporal variability of inundations and land use on the supply level and spatial distribution of ESs. The results of the analysis are summarized into a spatially explicit risk index, useful to rank coastal areas more prone to ESs losses or degradation due to coastal inundation at the national scale. Overall, the Northern Adriatic coast is scored at high risk of ESs loss or degradation in the future scenario. Other small coastal strips with medium risk scores are the Eastern Puglia coast, Western Sardinia, and Tuscany's coast. The ESs Coastal Risk Index provides an easy-to-understand screening assessment that could support the prioritization of areas for coastal adaptation at the national scale. Moreover, this index allows the direct evaluation of the public value of ecosystems and supports more effective territorial planning and environmental management decisions. In particular, it could support the mainstreaming of ecosystem-based approaches (e.g., ecological engineering and green infrastructures) to mitigate the risks of climate change and extreme events while protecting ecosystems and biodiversity. Integr Environ Assess Manag 2022;18:1564-1577. © 2021 SETAC.


Subject(s)
Climate Change , Ecosystem , Sea Level Rise , Biodiversity , Italy
18.
Nanotechnology ; 33(27)2022 Apr 20.
Article in English | MEDLINE | ID: mdl-35319494

ABSTRACT

We have explored the effect of high pressure post-treatment in optimizing the properties of carbon nanotube yarns and found that the application of dry hydrostatic pressure reduces porosity and enhances electrical properties. The CNT yarns were prepared by the dry-spinning method directly from CNT arrays made by the hot filament chemical vapour deposition (HF-CVD) process. Mechanical hydrostatic pressure up to 360 MPa induces a decrease in yarn resistivity between 3% and 35%, associated with the sample's permanent densification, with CNT yarn diameter reduction of 10%-25%. However, when increasing the pressure in the 1-3 GPa domain in non-hydrostatic conditions, the recovered samples show lower electrical conductivity. This might be due to concomitant macroscopic effects such as increased twists and damage to the yarn shown by SEM imaging (caused by strong shear stresses and friction) or by the collapse of the CNTs indicated byin situhigh pressure Raman spectroscopy data.

19.
Nat Chem ; 14(1): 85-93, 2022 01.
Article in English | MEDLINE | ID: mdl-34824461

ABSTRACT

Chirality and molecular conformation are central components of life: biological systems rely on stereospecific interactions between discrete (macro)molecular conformers, and the impacts of stereochemistry and rigidity on the properties of small molecules and biomacromolecules have been intensively studied. Nevertheless, how these features affect the properties of synthetic macromolecules has received comparably little attention. Here we leverage iterative exponential growth and ring-opening metathesis polymerization to produce water-soluble, chiral bottlebrush polymers (CBPs) from two enantiomeric pairs of macromonomers of differing rigidity. Remarkably, CBPs with conformationally flexible, mirror image side chains show several-fold differences in cytotoxicity, cell uptake, blood pharmacokinetics and liver clearance; CBPs with comparably rigid, mirror image side chains show no differences. These observations are rationalized with a simple model that correlates greater conformational freedom with enhanced chiral recognition. Altogether, this work provides routes to the synthesis of chiral nanostructured polymers and suggests key roles for stereochemistry and conformational rigidity in the design of future biomaterials.


Subject(s)
Polymers/chemistry , Molecular Conformation , Stereoisomerism
20.
Osteoporos Int ; 33(3): 725-735, 2022 Mar.
Article in English | MEDLINE | ID: mdl-34643755

ABSTRACT

Decreased cortical bone density and bone strength at peak height velocity (PHV) were noted in girls with adolescent idiopathic scoliosis (AIS). These findings could provide the link to the previously reported observation that low bone mineral density (BMD) could contribute as one of the prognostic factors for curve progression that mostly occurs during PHV in AIS. INTRODUCTION: As part of the studies related to aetiopathogenesis of AIS, we assessed bone qualities, bone mechanical strength and bone turnover markers (BTMs) focusing at the peri-pubertal period and PHV in AIS girls. METHODS: 396 AIS girls in two separate cohorts were studied. Skeletal maturity was assessed using the validated thumb ossification composite index (TOCI). Bone qualities and strength were evaluated with high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA). RESULTS: Cohort-A included 179 girls (11.95 ± 0.95 years old). Girls at TOCI-4 had numerically the highest height velocity (0.71 ± 0.24 cm/month) corresponding to the PHV. Subjects at TOCI-4 had lower cortical volumetric BMD (672.36 ± 39.07 mg/mm3), cortical thickness (0.68 ± 0.08 mm) and apparent modulus (1601.54 ± 243.75 N/mm2) than: (a) those at TOCI-1-3 (724.99 ± 32.09 mg/mm3 (p < 0.001), 0.79 ± 0.11 mm (p < 0.001) and 1910.88 ± 374.75 N/mm2 (p < 0.001), respectively) and (b) those at TOCI-8 (732.28 ± 53.75 mg/mm3 (p < 0.001), 0.84 ± 0.14 mm (p < 0.001), 1889.11 ± 419.37 N/mm2 (p < 0.001), respectively). Cohort-B included 217 girls (12.22 ± 0.89 years old). Subjects at TOCI-4 had higher levels of C-terminal telopeptide of type 1 collagen (1524.70 ± 271.10 pg/L) and procollagen type 1 N-terminal propeptide (941.12 ± 161.39 µg/L) than those at TOCI-8 (845.71 ± 478.55 pg/L (p < 0.001) and 370.08 ± 197.04 µg/L (p < 0.001), respectively). CONCLUSION: AIS girls had decreased cortical bone density and bone mechanical strength with elevated BTMs at PHV. Coupling of PHV with decreased cortical and FEA parameters could provide the link to the previously reported observation that low BMD could contribute as one of the prognostic factors for curve progression that mostly occurs during PHV in AIS.


Subject(s)
Scoliosis , Adolescent , Bone Density , Bone Remodeling , Child , Cortical Bone , Cross-Sectional Studies , Female , Humans , Longitudinal Studies , Scoliosis/diagnostic imaging
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