Alginate based biomaterials for hemostatic applications: Innovations and developments

Development of the efficient hemostatic materials is an essential requirement for the management of hemorrhage caused by the emergency situations to avert most of the casualties. Such injuries require the use of external hemostats to facilitate the immediate blood clotting. A variety of commercially available hemostats are present in the market but most of them are associated with limitations such as exothermic reactions, low biocompatibility, and painful removal. Thus, fabrication of an ideal hemostatic composition for rapid blood clot formation, biocompatibility, and antimicrobial nature presents a real challenge to the bioengineers. Benefiting from their tunable fabrication properties, alginate-based hemostats are gaining importance due to their excellent biocompatibility, with >85 % cell viability, high absorption capacity exceeding 500 %, and cost-effectiveness. Furthermore, studies have estimated that wounds treated with sodium alginate exhibited a blood loss of 0.40 ± 0.05 mL, compared to the control group with 1.15 ± 0.13 mL, indicating its inherent hemostatic activity. This serves as a solid foundation for designing future hemostatic materials. Nevertheless, various combinations have been explored to further enhance the hemostatic potential of sodium alginate. In this review, we have discussed the possible role of alginate based composite hemostats incorporated with different hemostatic agents, such as inorganic materials, polymers, biological agents, herbal agents, and synthetic drugs. This article outlines the challenges which need to be addressed before the clinical trials and give an overview of the future research directions.

Ultrasensitive Detection of Lipid-Induced Misfolding of the Prion Protein at the Aqueous-Liquid Crystal Interface

The misfolding of the α-helical cellular prion protein into a self-propagating β-rich aggregated form is a key pathogenic event in fatal and transmissible neurodegenerative diseases collectively known as prion diseases. Herein, we utilize the interfacial properties of liquid crystals (LCs) to monitor the lipid-membrane-induced conformational switching of prion protein (PrP) into β-rich amyloid fibrils. The lipid-induced conformational switching resulting in aggregation occurs at the nanomolar protein concentration and is primarily mediated by electrostatic interactions between PrP and lipid headgroups. Our LC-based methodology offers a potent and sensitive tool to detect and delineate molecular mechanisms of PrP misfolding mediated by lipid-protein interactions at the aqueous interface under physiological conditions.

Measurement of energy and directional distribution of neutron ambient dose equivalent for the 7Li(p,n)7Be reaction

Double differential neutron fluence distributions were measured in the 7Li(p,n)7Be reaction for proton beam energies 7, 9 and 12 MeV. Seven liquid scintillator based detectors were employed to measure neutron fluence distributions using the Time of Flight technique. Neutron ambient dose equivalents were determined from the measured fluence distribution using ICRP (International Commission on Radiological Protection) recommended fluence to dose equivalent conversion coefficients. Neutron dose equivalents were also measured using a conventional BF3 detector based REM counter. Ambient dose equivalent measured by the REM counter is found to be in agreement with that determined from the neutron fluence spectra within their uncertainties. Angular distributions of the ambient dose equivalents were also determined from the measured fluence distributions at different angles.

Erdafitinib versus pembrolizumab in pretreated patients with advanced or metastatic urothelial cancer with select FGFR alterations: cohort 2 of the randomized phase III THOR trial

BACKGROUND

Erdafitinib is an oral pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor approved to treat locally advanced/metastatic urothelial carcinoma (mUC) in patients with susceptible FGFR3/2 alterations (FGFRalt) who progressed after platinum-containing chemotherapy. FGFR-altered tumours are enriched in luminal 1 subtype and may have limited clinical benefit from anti-programmed death-(ligand) 1 [PD-(L)1] treatment. This cohort in the randomized, open-label phase III THOR study assessed erdafitinib versus pembrolizumab in anti-PD-(L)1-naive patients with mUC.

PATIENTS AND METHODS

Patients ≥18 years with unresectable advanced/mUC, with select FGFRalt, disease progression on one prior treatment, and who were anti-PD-(L)1-naive were randomized 1 : 1 to receive erdafitinib 8 mg once daily with pharmacodynamically guided uptitration to 9 mg or pembrolizumab 200 mg every 3 weeks. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and safety.

RESULTS

The intent-to-treat population (median follow-up 33 months) comprised 175 and 176 patients in the erdafitinib and pembrolizumab arms, respectively. There was no statistically significant difference in OS between erdafitinib and pembrolizumab [median 10.9 versus 11.1 months, respectively; hazard ratio (HR) 1.18; 95% confidence interval (CI) 0.92-1.51; P = 0.18]. Median PFS for erdafitinib and pembrolizumab was 4.4 and 2.7 months, respectively (HR 0.88; 95% CI 0.70-1.10). ORR was 40.0% and 21.6% (relative risk 1.85; 95% CI 1.32-2.59) and median duration of response was 4.3 and 14.4 months for erdafitinib and pembrolizumab, respectively. 64.7% and 50.9% of patients in the erdafitinib and pembrolizumab arms had ≥1 grade 3-4 adverse events (AEs); 5 (2.9%) and 12 (6.9%) patients, respectively, had AEs that led to death.

CONCLUSIONS

Erdafitinib and pembrolizumab had similar median OS in this anti-PD-(L)1-naive, FGFR-altered mUC population. Outcomes with pembrolizumab were better than assumed and aligned with previous reports in non- FGFR-altered populations. Safety results were consistent with the known profiles for erdafitinib and pembrolizumab in this patient population.

Single-molecule FRET unmasks structural subpopulations and crucial molecular events during FUS low-complexity domain phase separation

Biomolecular condensates formed via phase separation of proteins and nucleic acids are thought to be associated with a wide range of cellular functions and dysfunctions. We dissect critical molecular events associated with phase separation of an intrinsically disordered prion-like low-complexity domain of Fused in Sarcoma by performing single-molecule studies permitting us to access the wealth of molecular information that is skewed in conventional ensemble experiments. Our single-molecule FRET experiments reveal the coexistence of two conformationally distinct subpopulations in the monomeric form. Single-droplet single-molecule FRET studies coupled with fluorescence correlation spectroscopy, picosecond time-resolved fluorescence anisotropy, and vibrational Raman spectroscopy indicate that structural unwinding switches intramolecular interactions into intermolecular contacts allowing the formation of a dynamic network within condensates. A disease-related mutation introduces enhanced structural plasticity engendering greater interchain interactions that can accelerate pathological aggregation. Our findings provide key mechanistic underpinnings of sequence-encoded dynamically-controlled structural unzipping resulting in biological phase separation.

Enhanced oil-water emulsion separation through coalescence filtration utilizing milkweed fiber: a sustainable paradigm

Over the past few years, the environment and public safety have suffered due to the detrimental effects of oily industrial effluents. Natural fibers have gained popularity for their affordability, reusability, and effectiveness in separating oil from oily wastewater. Milkweed fibers were characterized using FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and contact angle techniques. With four porosities (0.90, 0.92, 0.95, and 0.98), deep bed coalescence filters were built at three different filter bed heights (10 mm, 20 mm, and 30 mm). Using milkweed coalescence filtering technology, a novel oil separation method is described along with a method to calculate oil film thickness following emulsified oily water saturation. By combining a bed height of 30 mm and a porosity of 0.98, a maximum oil separation of 99.73% and an optimized D50 droplet ratio were achieved. Throughout a prolonged operational period lasting 250 min, the filter bed, possessing a depth of 30 mm and a porosity of 98%, exhibited no discernible fouling indications. Following five cycles, the milkweed filter bed measuring 30 mm in depth and featuring a porosity of 98% displayed an impressive oil separation efficiency of 91.5%. This study found that using a milkweed deep bed filter, coalescence filtering effectively removes oil from oily effluent. Furthermore, milkweed is a natural and biodegradable fiber that is easy to dispose of after use and does not harm the environment.

Development of κ-carrageenan-PEG/lecithin bioactive hydrogel membranes for antibacterial adhesion and painless detachment

The issue of wound dressing adherence poses a substantial challenge in the field of wound care, with implications both clinically and economically. Overcoming this challenge requires the development of a hydrogel dressing that enables painless removal without causing any secondary damage. However, addressing this issue still remains a significant challenge that requires attention and further exploration. The present study is focused on the synthesis of hydrogel membranes based on κ-carrageenan (CG), polyethylene glycol (PEG), and soy lecithin (LC), which can provide superior antioxidant and antibacterial attachment properties with a tissue anti adhesion activity for allowing an easy removability without causing secondary damage. The (CG-PEG)/LC mass ratio was varied to fabricate hydrogel membranes via a facile approach of physical blending and solution casting. The physicochemical properties of (CG-PEG)/LC hydrogel membranes were studied by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and mechanical analyses. The membranes showed significantly enhanced mechanical properties with excellent flexibility and had high swelling capacity (˃1000 %), which would provide a moist condition for wound healing. The membranes also exhibited excellent free radical scavenging ability (>60 %). In addition, the (CG-PEG)/LC hydrogel membranes showed reduced peel strength 26.5 N/m as a result of weakening the hydrogel-gelatin interface during an in vitro gelatin peeling test. Moreover, the membrane showed superior antibacterial adhesion activity (>90 %) against both S. aureus and E. coli due to the presence of both PEG and LC. The results also suggested that the hydrogel membranes exhibit NIH3T3 cell antiadhesion property, making them promising material for easy detachment from the healed tissue without causing secondary damage. Thus, this novel combination of (CG-PEG)/LC hydrogel membranes have immense application potential as a biomaterial in the healthcare sector.

Superconductivity from a melted insulator in Josephson junction arrays

Arrays of Josephson junctions are governed by a competition between superconductivity and repulsive Coulomb interactions, and are expected to exhibit diverging low-temperature resistance when interactions exceed a critical level. Here we report a study of the transport and microwave response of Josephson arrays with interactions exceeding this level. Contrary to expectations, we observe that the array resistance drops dramatically as the temperature is decreased-reminiscent of superconducting behaviour-and then saturates at low temperature. Applying a magnetic field, we eventually observe a transition to a highly resistive regime. These observations can be understood within a theoretical picture that accounts for the effect of thermal fluctuations on the insulating phase. On the basis of the agreement between experiment and theory, we suggest that apparent superconductivity in our Josephson arrays arises from melting the zero-temperature insulator.

Nontoxic Cross-Linked Graphitic Carbon Nitride-Alginate-Based Biodegradable Transparent Films for UV and High-Energy Blue Light Shielding

Flexible, transparent, and biodegradable films that can shield dangerous UV and high-energy blue light (HEBL) are high in demand to satisfy the ever-increasing expectations for environmental sustainability. To achieve this goal, biopolymer alginate is an excellent choice that has an outstanding film-forming ability. However, alginate has the limitation of poor UV and HEBL blocking ability. Thus, in this study, UV and HEBL blocker graphitic carbon nitride (g-C₃N₄) was incorporated in alginate films to enhance the compatibility, applicability, and durability. The ATR-FTIR, TGA, DTG, and FE-SEM results indicated that the composite film formation was due to hydrogen bonding, and the composite films revealed synergistic properties of alginate and g-C₃N₄. Though the incorporation of g-C₃N₄ in films enhanced the mechanical and thermal stabilities of the films, the films were still flexible. The UV-visible transmittance characterization confirmed that the prepared films could block both UV and HEBL radiation while maintaining transparency in visible regions. In experiments involving only 2 wt % g-C₃N₄, nearly 90% of UV (200-400 nm) and 95% of HEBL (400-450 nm) irradiation were blocked. Additionally, the inclusion of g-C₃N₄ also facilitated the biodegradation process of composite films. Moreover, after 6 months, the composite films exhibited excellent UV and HEBL shielding with excellent mechanical durability.

Hydrogen-Deuterium Exchange Vibrational Raman Spectroscopy Distinguishes Distinct Amyloid Polymorphs Comprising Altered Core Architecture

Amyloid fibrils are ordered protein aggregates comprising a hydrogen-bonded central cross-β core displaying a structural diversity in their supramolecular packing arrangements within the core. Such an altered packing results in amyloid polymorphism that gives rise to morphological and biological strain diversities. Here, we show that vibrational Raman spectroscopy coupled with hydrogen/deuterium (H/D) exchange discerns the key structural features that are responsible for yielding diverse amyloid polymorphs. Such a noninvasive and label-free methodology allows us to structurally distinguish distinct amyloid polymorphs displaying altered hydrogen bonding and supramolecular packing within the cross-β structural motif. By using quantitative molecular fingerprinting and multivariate statistical analysis, we analyze key Raman bands for the protein backbone and side chains that allow us to capture the conformational heterogeneity and structural distributions within distinct amyloid polymorphs. Our results delineate the key molecular factors governing the structural diversity in amyloid polymorphs and can potentially simplify studying amyloid remodeling by small molecules.

Sustainable Photocatalytic Desizing Process for the Starch-Based Size

Textile wet processing highly impacts the environment due to its massive water and energy consumption. High consumption of water also results in the generation of a considerable volume of effluents. In this regard, an ultraviolet C (UVC)-assisted desizing method of starch-sized cotton fabric has been developed to lower the utility consumption in textile pretreatment. A UVC cabinet is designed to control exposing temperature and energy of exposure on the starch-sized cotton fabric. The UVC exposure time is optimized concerning the desizing efficiency. The UVC-exposed-sized fabric is washed with different washing times and washing temperatures to optimize the process. The alkali consumption in washing is reduced by 75% and desizing efficiency is improved to 95%. The application of oxidizing agents like NaNO₂, K₂S₂O₈, and NaBO₃·4H₂O during sizing further reduced the washing temperature and washing time for desizing to obtain 100% desizing efficiency. The UVC-assisted desized fabric is characterized by the whiteness index, water absorbency, tensile strength, Fourier transform infrared (FTIR), and wide-angle X-ray diffraction and compared with the control. The UVC-assisted desizing process has the potential to save approximately 60% water, 90% energy, and more than 70% of the time. Life cycle analysis has also been done. The photocatalytic desizing process can reduce the impact on human health by more than 85% and save approximately 69% of mineral resources than the conventional technique. The textile industry can quickly adopt a novel approach for sustainable desizing.

Preparation of functional and reactive nanosilver nanogels using oxidized carboxymethyl cellulose

The designing of functional and reactive nanosilver has been carried out by in-situ reduction of silver nitrate using oxidized carboxymethyl cellulose (OCMC). The reduction process is also accompanied by the stabilization of nanoparticles using the OCMC polymer chain, leading to the formation of a structure where nanosilver is entrapped within OCMC gel. The silver nanogels characterized using transmission electron microscopy (TEM) are found to be ∼22 nm. By virtue of the presence of dialdehyde functionality around the silver nanogels, they have the ability to react with a polymer having a complementary functional group. The nanogels have exhibited prominent antimicrobial activity against both gram-negative and gram-positive bacteria. It has been observed that a 0.3 mM concentration of silver nanogel is active in inhibiting bacterial growth. The antibacterial activity of the synthesized Ag nanogels was dose-dependent, with 99.9 % of E. coli and S. aureus destroyed within 5 h at a concentration of 0.4 mM Ag nanogels. The nanogels disrupted the bacterial cell wall and generated reactive oxygen species inside the cell, which resulted in cell death. This investigation provides a very interesting application as a coating for biomedical implants and devices.

The bacterial nucleoid-associated proteins, HU, and Dps, condense DNA into context-dependent biphasic or multiphasic complex coacervates

The bacterial chromosome, known as its nucleoid, is an amorphous assemblage of globular nucleoprotein domains. It exists in a state of phase separation from the cell's cytoplasm, as an irregularly-shaped, membrane-less, intracellular compartment. This state (the nature of which remains largely unknown) is maintained through bacterial generations ad infinitum. Here, we show that HU, and Dps, two of the most abundant nucleoid-associated proteins (NAPs) of Escherichia coli, undergo spontaneous complex coacervation with different forms of DNA/RNA, both individually and in each other's presence, to cause accretion and compaction of DNA/RNA into liquid-liquid phase separated (LLPS) condensates in vitro. Upon mixing with nucleic acids, HU-A and HU-B form (a) bi-phasic heterotypic mixed condensates in which HU-B helps to lower the C_sat of HU-A; and also (b) multi-phasic heterotypic condensates, with Dps, in which de-mixed domains display different contents of HU and Dps. We believe that these modes of complex coacervation that are seen in vitro can serve as models for the in vivo relationships amongst NAPs in nucleoids, involving local and global variations in the relative abundances of the different NAPs, especially in de-mixed sub-domains that are characterized by differing grades of phase separation. Our results clearly demonstrate some quantitative, and some qualitative, differences in the coacervating abilities of different NAPs with DNA, potentially explaining (i) why E. coli has two isoforms of HU, and (ii) why changes in the abundances of HU and Dps facilitate the lag, logarithmic and stationary phases of E. coli growth.

Biophysics of biomolecular condensates

The formation of biomolecular condensates has emerged as a new biophysical principle for subcellular compartmentalization within cells to facilitate the spatiotemporal regulation of a multitude of complex biomolecular reactions. In this Research Highlight, we summarize the findings that were published in Biophysical Journal during the past two years (2021 and 2022). These papers provided biophysical insights into the formation of biomolecular condensates via phase separation of proteins with or without nucleic acids.

ATP modulates self-perpetuating conformational conversion generating structurally distinct yeast prion amyloids that limit autocatalytic amplification

Prion-like self-perpetuating conformational conversion of proteins into amyloid aggregates is associated with both transmissible neurodegenerative diseases and non-Mendelian inheritance. The cellular energy currency ATP is known to indirectly regulate the formation, dissolution, or transmission of amyloid-like aggregates by providing energy to the molecular chaperones that maintain protein homeostasis. In this work, we demonstrate that ATP molecules, independent of any chaperones, modulate the formation and dissolution of amyloids from a yeast prion domain (NM domain of Saccharomyces cerevisiae Sup35) and restricts autocatalytic amplification by controlling the amount of fragmentable and seeding-competent aggregates. ATP, at (high) physiological concentrations in the presence of Mg²⁺, kinetically accelerates NM aggregation. Interestingly, ATP also promotes phase-separation-mediated aggregation of a human protein harboring a yeast prion-like domain. We also show that ATP disaggregates preformed NM fibrils in a dose-independent manner. Our results indicate that ATP-mediated disaggregation, unlike the disaggregation by the disaggregase Hsp104, yields no oligomers that are considered one of the critical species for amyloid transmission. Furthermore, high concentrations of ATP delimited the number of seeds by giving rise to compact, ATP-bound NM fibrils that exhibited nominal fragmentation by either free ATP or Hsp104 disaggregase to generate lower molecular weight amyloids. Additionally, (low) pathologically relevant ATP concentrations restricted autocatalytic amplification by forming structurally distinct amyloids which are found seeding-inefficient due to their reduced β-content. Our results provide key mechanistic underpinnings of concentration-dependent chemical chaperoning by ATP against prion-like transmissions of amyloids.

Oil separation from oil in water emulsion by coalescence filtration using kapok fibre

In this study, the stable emulsion of engine oil in water of concentration 10% was prepared using a non-ionic surfactant. Kapok fibres were used as filter beds to separate oil from the oil-water emulsion. The surface morphology of fibres was investigated using Scanning Electron Microscope (SEM) analysis and chemical bond analysis of fibres done using Fourier transform infrared (FTIR). Kapok filter beds were prepared with three different bed heights 10, 20 and 30 mm each with four different porosities 0.90, 0.92, 0.95 and 0.98 for preparing the coalescence filter. The oil-water emulsion (influent) was pumped into the filtration column and the coalesced oil droplets, water, as well as un-coalesced oil droplets, especially the finer oil droplets, were collected as effluent. Oil separation efficiency was evaluated in terms of change in droplet size (D50) and oil concentration from influent to effluent. With increasing porosity and bed height, apart from porosity of 0.92, the separation efficiency increases. Increasing the bed heights at lower porosities does not improve the efficiency of the process. A combination of 0.98 porosity and a bed height of 30 mm provided the highest filtration performance in terms of oil separation efficiency and D50 droplet ratio. At 0.98 porosity, increasing the bed height from 10 mm to 30 mm resulted in a D50 droplet ratio of 0.25-0.14, representing a significant decrease in droplet size in the effluent and therefore an increase in oil separation efficiency from 91.3% to 99.63%.

Molecular Origin of Internal Friction in Intrinsically Disordered Proteins

Protein folding and dynamics are controlled by an interplay of thermal and viscosity effects. The effect of viscous drag through the solvent molecules is described by the classic Kramers theory in the high friction limit, which considers the dampening of the reactant molecules in the solution and quantifies the dependence of the reaction rate on the frictional drag. In addition to the external energy dissipation originating from the surrounding solvent molecules, there is an additional mode of internal energy dissipative force operative within the polypeptide chain reflecting the internal resistance of the chain to its conformational alterations. This dry, solvent-independent intrinsic frictional drag is termed internal friction. In the case of natively folded proteins, the physical origin of internal friction is primarily attributed to the intrachain interactions or other nonnative interactions in their compact states. However, the molecular origin of internal friction in intrinsically disordered proteins (IDPs) remains elusive.In this Account, we address this fundamental issue: what are the principal drivers of viscosity-independent (dry) friction in highly solvated, expanded, conformationally flexible, rapidly fluctuating IDPs that do not possess persistent intrachain interactions? IDPs exhibit diffusive conformational dynamics that is predominantly dominated by the segmental motion of the backbone arising due to the dihedral rotations in the Ramachandran Φ-Ψ space. The physical origin of friction in a complex biopolymeric system such as IDPs can be described by classic polymer models, namely, Rouse/Zimm models with internal friction. These one-dimensional models do not invoke torsional fluctuation components. Kuhn's classic description includes the connection between internal friction and microscopic dihedral hopping. Based on our time-resolved fluorescence anisotropy results, we describe that the sequence-dependent, collective, short-range backbone dihedral rotations govern localized internal friction in an archetypal IDP, namely, α-synuclein. The highly sensitive, residue-specific fluorescence depolarization kinetics offers a potent methodology to characterize and quantify the directional decorrelation engendered due to the short-range dihedral relaxation of the polypeptide backbone in the dihedral space. We utilized this characteristic relaxation time scale as our dynamic readout to quantify the site-specific frictional component. Our linear viscosity-dependent model of torsional relaxation time scale furnished a finite nonzero time constant at the zero solvent viscosity representing the solvent-independent internal friction. These results unveil the effect of the degree of dihedral restraining parameter on the internal friction component by showing that a restrained proline residue imparts higher torsional stiffness in the chain segments and, therefore, exhibits higher internal friction. This Account sheds light on the molecular underpinning of the sequence-specific internal friction in IDPs and will be of interest to unmask the role of internal friction in a diverse range of biomolecular processes involving binding-induced folding, allosteric interaction, protein misfolding and aggregation, and biomolecular condensation via phase separation.

385 Service Evaluation of the Management of Acute Cholecystitis in the Royal Gwent Hospital Pre and During the COVID-19 Pandemic

Aim

NICE guidelines set out the criteria for the treatment of patients with acute cholecystitis and the operative timescales for cholecystectomy. These targets were greatly affected during the Covid-19 pandemic. Therefore, we aimed to assess the impact that COVID-19 had on patients presenting with acute cholecystitis at a busy district general hospital. June 2020, compared with patients who presented with the same in June 2019.

Method

Patient cohorts were identified for matching seasons pre- and post-covid-19 (June 2019 and June 2020). Data of all patients who presented with acute cholecystitis was obtained using an electronic patient management system. Statistical analyses were performed using a Wilcoxon test.

Results

The results of the study indicate that waiting times post-covid are going down (p<0.05). Thus, days until cholecystectomy have decreased but the number of patients being operated on too has decreased thus further worsening waiting times for elective patients. The median and IQR's of days to surgery post-covid are 198 (121.5–278) and pre-covid are 251 (89.5–586.5). Presentations of gallstone complications almost doubled post-covid and the percentage of patients operated on decreased by over 20%.

Conclusions

It is clear from the data that the NICE guidance on the management of acute cholecystitis has been difficult to adhere to during the pandemic. While the time from diagnosis to operation has reduced post-covid the total number of operations has decreased drastically, putting further strain on elective waiting lists. This, inevitably, will result in further presentations of complications from gallstones and adverse patient outcomes.

Single-droplet surface-enhanced Raman scattering decodes the molecular determinants of liquid-liquid phase separation

Biomolecular condensates formed via liquid-liquid phase separation (LLPS) are involved in a myriad of critical cellular functions and debilitating neurodegenerative diseases. Elucidating the role of intrinsic disorder and conformational heterogeneity of intrinsically disordered proteins/regions (IDPs/IDRs) in these phase-separated membrane-less organelles is crucial to understanding the mechanism of formation and regulation of biomolecular condensates. Here we introduce a unique single-droplet surface-enhanced Raman scattering (SERS) methodology that utilizes surface-engineered, plasmonic, metal nanoparticles to unveil the inner workings of mesoscopic liquid droplets of Fused in Sarcoma (FUS) in the absence and presence of RNA. These highly sensitive measurements offer unprecedented sensitivity to capture the crucial interactions, conformational heterogeneity, and structural distributions within the condensed phase in a droplet-by-droplet manner. Such an ultra-sensitive single-droplet vibrational methodology can serve as a potent tool to decipher the key molecular drivers of biological phase transitions of a wide range of biomolecular condensates involved in physiology and disease.

The authors introduce a unique single-droplet surface-enhanced Raman scattering (SERS) methodology that illuminates a wealth of molecular information within the mesoscopic liquid condensed phase of Fused in Sarcoma in the absence and presence of RNA.

Development of sodium alginate/glycerol/tannic acid coated cotton as antimicrobial system

Present study aims at developing antimicrobial cotton gauze by dip coating of sodium alginate (SA), glycerol (Gly) and tannic acid (TA) blend. SA blends were prepared with varying concentration of glycerol in the range of 10-40 %. Blended films were fabricated and characterized by Fourier transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD), tensile studies, and contact angle analysis. The mechanical behavior of films indicated significant decrease in the tensile strength and modulus with the increase in the glycerol content due to the plasticization effect. The hydrophilicity of the blend films increased with increase in the glycerol content. TA was added to the blend as an antimicrobial agent. These blends were coated on the cotton gauze by dip coating method and their characterizations were carried out by the scanning electron microscopy (SEM) which revealed a smooth coating of SA:Gly:TA blend on cotton gauze. Antimicrobial analysis of TA coated gauzes was carried out which showed >95 % viable colony reduction against E. coli and S. aureus. Cytocompatibility studies indicated excellent cell-compatible activity. These results implicated that such coated gauzes are promising candidate that hold the great potential to be utilized as infection-resistant material in the health care sector.

Sub-stoichiometric Hsp104 regulates the genesis and persistence of self-replicable amyloid seeds of Sup35 prion domain

Prion-like self-perpetuating conformational conversion of proteins is involved in both transmissible neurodegenerative diseases in mammals and non-Mendelian inheritance in yeast. The transmissibility of amyloid-like aggregates is dependent on the stoichiometry of chaperones such as heat shock proteins (Hsps), including disaggregases. To provide the mechanistic underpinnings of the formation and persistence of prefibrillar amyloid seeds, we investigated the role of substoichiometric Hsp104 on the in vitro amyloid aggregation of the prion domain (NM-domain) of Saccharomyces cerevisiae Sup35. At low substoichiometric concentrations, we show Hsp104 exhibits a dual role: it considerably accelerates the formation of prefibrillar species by shortening the lag phase but also prolongs their persistence by introducing unusual kinetic halts and delaying their conversion into mature amyloid fibers. Additionally, Hsp104-modulated amyloid species displayed a better seeding capability compared to NM-only amyloids. Using biochemical and biophysical tools coupled with site-specific dynamic readouts, we characterized the distinct structural and dynamical signatures of these amyloids. We reveal that Hsp104-remodeled amyloidogenic species are compositionally diverse in prefibrillar aggregates and are packed in a more ordered fashion compared to NM-only amyloids. Finally, we show these Hsp104-remodeled, conformationally distinct NM aggregates display an enhanced autocatalytic self-templating ability that might be crucial for phenotypic outcomes. Taken together, our results demonstrate that substoichiometric Hsp104 promotes compositional diversity and conformational modulations during amyloid formation, yielding effective prefibrillar seeds that are capable of driving prion-like Sup35 propagation. Our findings underscore the key functional and pathological roles of substoichiometric chaperones in prion-like propagation.

Synthesis of PEDOT:PSS Solution-Processed Electronic Textiles for Enhanced Joule Heating

Textile-based flexible and wearable electronic devices provide an excellent solution to thermal management systems, thermal therapy, and deicing applications through the Joule heating approach. However, challenges persist in designing such cost-effective electronic devices for efficient heating performance. Herein, this study adopted a facile solution-processed strategy, "dip-coating", to develop a high-performance Joule heating device by unformly coating the intrinsically conducting polymer (CP) poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) onto the surface of cotton textiles. The structural and morphological attributes of the cotton/CP mixture were evaluated using various characterization techniques. The electrothermal characteristics of the cotton/CP sample included rapid thermal response, uniform surface temperature distribution up to 94 °C, excellent stability, and endurance in heating performance under various mechanical deformations. The real-time illustration of the fabric heater affixed on a human finger has demonstrated its outstanding potential for thermal therapy applications. The fabricated heater may further expand it purposes toward deicing, defogging, and defrosting applications.

Estradiol inhibits HIV-1BaL infection and induces CFL1 expression in peripheral blood mononuclear cells and endocervical mucosa

An inhibitory effect of estradiol (E2) on HIV-1 infection was suggested by several reports. We previously identified increased gene expression of actin-binding protein cofilin 1 (CFL1) in endocervix in the E2-dominated proliferative phase of the menstrual cycle. Actin cytoskeleton has an integral role in establishing and spreading HIV-1 infection. Herein, we studied in vitro effects of E2 on HIV-1 infection and on CFL1 expression to gain insight into the mechanism of HIV-1 inhibition by E2. E2 dose-dependently inhibited HIV-1_BaL infection in peripheral blood mononuclear cells (PBMCs) and endocervix. In PBMCs and endocervix, E2 increased protein expression of total CFL1 and phosphorylated CFL1 (pCFL1) and pCFL1/CFL1 ratios. LIMKi3, a LIM kinase 1 and 2 inhibitor, abrogated the phenotype and restored infection in both PBMCs and endocervix; inhibited E2-induced expression of total CFL1, pCFL1; and decreased pCFL1/CFL1 ratios. Knockdown of CFL1 in PBMCs also abrogated the phenotype and partially restored infection. Additional analysis of soluble mediators revealed decreased concentrations of pro-inflammatory chemokines CXCL10 and CCL5 in infected tissues incubated with E2. Our results suggest a link between E2-mediated anti-HIV-1 activity and expression of CFL1 in PBMCs and endocervical mucosa. The data support exploration of cytoskeletal signaling pathway targets for the development of prevention strategies against HIV-1.

Dysregulation of macrophage PEPD in obesity determines adipose tissue fibro-inflammation and insulin resistance

Resulting from impaired collagen turnover, fibrosis is a hallmark of adipose tissue (AT) dysfunction and obesity-associated insulin resistance (IR). Prolidase, also known as peptidase D (PEPD), plays a vital role in collagen turnover by degrading proline-containing dipeptides but its specific functional relevance in AT is unknown. Here we show that in human and mouse obesity, PEPD expression and activity decrease in AT, and PEPD is released into the systemic circulation, which promotes fibrosis and AT IR. Loss of the enzymatic function of PEPD by genetic ablation or pharmacological inhibition causes AT fibrosis in mice. In addition to its intracellular enzymatic role, secreted extracellular PEPD protein enhances macrophage and adipocyte fibro-inflammatory responses via EGFR signalling, thereby promoting AT fibrosis and IR. We further show that decreased prolidase activity is coupled with increased systemic levels of PEPD that act as a pathogenic trigger of AT fibrosis and IR. Thus, PEPD produced by macrophages might serve as a biomarker of AT fibro-inflammation and could represent a therapeutic target for AT fibrosis and obesity-associated IR and type 2 diabetes.

Preparation of thyme oil loaded κ-carrageenan-polyethylene glycol hydrogel membranes as wound care system

The present study is aimed at fabricating thyme oil loaded hydrogel membranes composed of κ-carrageenan (CG) and polyethylene glycol (PEG), which can provide moist environment and prevent infections for rapid wound healing. Membranes were prepared with different amounts of PEG via solvent casting technique under ambient conditions. Physicochemical properties of CG-PEG membranes as a function of the PEG content were investigated. The surface morphology of membranes displayed smoother surfaces with increasing PEG content up to 40%. In addition, the interaction of PEG with CG polymer chains was evaluated in terms of Free and bound PEG fraction within the membrane matrix. Furthermore, thyme oil (TO) was added to enhance the antibacterial properties of CG-PEG membranes. These membranes showed >95% antimicrobial activity against both gram-positive and gram-negative bacteria depending on the TO content. Suggesting the great potential of these membranes as a strong candidate for providing an effective antimicrobial nature in human healthcare.

Subclinical left and right ventricular dysfunction in COVID-19 recovered patients using speckle tracking echocardiography

Funding Acknowledgements

Type of funding sources: None.

Introduction

Myocardial injury during acute COVID-19 infection is well characterised however, its persistence during recovery is unclear.

Purpose

We assessed left ventricle (LV) global longitudinal strain (GLS) and right ventricular (RV) free wall longitudinal strain and RV global longitudinal strain (RV-GLS) using speckle tracking echocardiography (STE) in COVID-19 recovered patients (30-45 days post recovery) and studied its correlation with various parameters.

Methods

Of the 245 subjects screened, a total of 53 subjects recovered from COVID-19 infection and normal LV ejection fraction were enrolled. Routine blood investigations, inflammatory markers (on admission) and comprehensive echocardiography including STE were done for all.

Results

All the 53 subjects were symptomatic during COVID-19 illness and were categorized as mild: 27 (50.9%), moderate: 20 (37.7%) and severe: 6 (11.4%) COVID-19 illness. Reduced LV GLS was reported in 22 (41.5%), reduced RV-GLS in 23 (43.4%) and reduced RVFWS in 22 (41.5%) patients respectively. LVGLS was significantly lower in patients recovered from severe illness (mild: -20.3 ± 1.7%; moderate: -15.3 ± 3.4%; severe: -10.7 ± 5.1%; P < 0.0001). Similarly, RVGLS (mild: -21.8 ± 2.8%; moderate: -16.8 ± 4.8%; severe: -9.7 ± 4.6%; P < 0.0001) and RVFWS (mild: -23.0 ± 4.1%; moderate: -18.1 ± 5.5%; severe: -9.3 ± 4.4%; P < 0.0001) were significantly lower in subjects with severe COVID-19. Subjects with reduced LVGLS as well as RVGLS and RVFWS had significantly higher interleukin-6, C-reactive protein, lactate dehydrogenase and serum ferritin levels during index admission.

Conclusions

Subclinical LV and RV dysfunction was seen in majority of  COVID-19 recovered patients. Patients with severe disease during index admission had far lower LV and RVGLS as compared to mild and moderate cases. Our study highlights the need for close follow-up of COVID-19 recovered subjects in order to determine the long-term cardiovascular outcomes.

Conformational and Solvation Dynamics of an Amyloidogenic Intrinsically Disordered Domain of a Melanosomal Protein

The conformational plasticity of intrinsically disordered proteins (IDPs) allows them to adopt a range of conformational states that can be important for their biological functions. The driving force for the conformational preference of an IDP emanates from an intricate interplay between chain-chain and chain-solvent interactions. Using ultrafast femtosecond and picosecond time-resolved fluorescence measurements, we characterized the conformational and solvation dynamics around the N- and C-terminal segments of a disordered repeat domain of a melanosomal protein Pmel17 that forms functional amyloid responsible for melanin biosynthesis. Our time-resolved fluorescence anisotropy results revealed slight compaction and slower rotational dynamics around the amyloidogenic C-terminal segment when compared to the proline-rich N-terminal segment of the repeat domain. The compaction of the C-terminal region was also associated with the restrained mobility of hydration water as indicated by our solvation dynamics measurements. Our findings indicate that sequence-dependent chain-solvent interactions govern both the conformational and solvation dynamics that are crucial in directing the conversion of a highly dynamic IDP into an ordered amyloid assembly. Such an interplay of amino acid composition-dependent conformational and solvation dynamics might have important physicochemical consequences in specific water-protein, ion-protein, and protein-protein interactions involved in amyloid formation and phase transitions.

An intrinsically disordered pathological prion variant Y145Stop converts into self-seeding amyloids via liquid-liquid phase separation

Biomolecular condensation via liquid-liquid phase separation of intrinsically disordered proteins/regions (IDPs/IDRs) along with other biomolecules is proposed to control critical cellular functions, whereas aberrant phase transitions are associated with a range of neurodegenerative diseases. Here, we show that a disease-associated stop codon mutation of the prion protein (PrP) at tyrosine 145 (Y145Stop), resulting in a truncated, highly disordered, N-terminal IDR, spontaneously phase-separates into dynamic liquid-like droplets. Phase separation of this highly positively charged N-terminal segment is promoted by the electrostatic screening and a multitude of weak, transient, multivalent, intermolecular interactions. Single-droplet Raman measurements, in conjunction with an array of bioinformatic, spectroscopic, microscopic, and mutagenesis studies, revealed a highly mobile internal organization within the liquid-like condensates. The phase behavior of Y145Stop is modulated by RNA. Lower RNA:protein ratios promote condensation at a low micromolar protein concentration under physiological conditions. At higher concentrations of RNA, phase separation is abolished. Upon aging, these highly dynamic liquid-like droplets gradually transform into ordered, β-rich, amyloid-like aggregates. These aggregates formed via phase transitions display an autocatalytic self-templating characteristic involving the recruitment and binding-induced conformational conversion of monomeric Y145Stop into amyloid fibrils. In contrast to this intrinsically disordered truncated variant, the wild-type full-length PrP exhibits a much lower propensity for both condensation and maturation into amyloids, hinting at a possible protective role of the C-terminal domain. Such an interplay of molecular factors in modulating the protein phase behavior might have much broader implications in cell physiology and disease.

The management of severe aortic stenosis during the COVID-19 pandemic: an observational study comparing TAVI and SAVR

Introduction

Outcomes and characteristics of patients with severe aortic stenosis (AS) treated during the COVID-19 pandemic is unknown.

Methods

This was a single-centre observational study of patients undergoing AS treatment with transcatheter (TAVI) or surgical (SAVR) therapy during the first-wave of the UK COVID-19 pandemic compared to a control cohort undergoing treatment in 2019.

Demographics, baseline echocardiogram, CT, procedural characteristics and outcome data were collated. The primary outcome was 30-day all-cause mortality. The secondary endpoint was duration of post-procedural hospitalisation.

Results

319 patients were recruited - 122 underwent intervention during the pandemic [73 TAVI; 49 SAVR] and 197 in 2019 [127 TAVI; 70 SAVR].

In 2020, TAVI patients had a higher Euroscore II (p&lt;0.001) but there were no differences in procedural complications or mortality [p=0.16] compared to TAVI 2019 cases. Duration from TAVI to discharge was shorter in 2020 (p&lt;0.001).

SAVR 2020 patients had similar baseline profile [p=0.48], surgical characteristics, mortality (p=0.68) and duration from SAVR to discharge compared to those in 2019.

During the pandemic, TAVI patients were older (p&lt;0.001) and had a higher Euroscore II (p&lt;0.001) than SAVR counterparts. TAVI patients had reduced 30-day mortality [0 (0%) vs 3 (6%); p=0.06] and were discharged more rapidly post-intervention than SAVR patients [median 1 [1] vs 7 [4] days; p&lt;0.001) translating into shorter hospitalization (p&lt;0.001).

Conclusions

TAVI and SAVR can be safely delivered with predictable resource utilisation during a pandemic. Despite the TAVI cohort incorporating higher risk, older patients, outcomes were at least as good as SAVR with a shorter length of post-procedural hospitalisation.

Funding Acknowledgement

Type of funding sources: None. Procedural Complications TAVI/SAVRDuration to discharge post TAVI/SAVR

Distinct types of amyloid-β oligomers displaying diverse neurotoxicity mechanisms in Alzheimer's disease

Soluble oligomers of amyloid-β (Aβ) are recognized as key pernicious species in Alzheimer's disease (AD) that cause synaptic dysfunction and memory impairments. Numerous studies have identified various types of Aβ oligomers having heterogeneous peptide length, size distribution, structure, appearance, and toxicity. Here, we review the characteristics of soluble Aβ oligomers based on their morphology, size, and structural reactivity toward the conformation-specific antibodies and then describe their formation, localization, and cellular effects in AD brains, in vivo and in vitro. We also summarize the mechanistic pathways by which these soluble Aβ oligomers cause proteasomal impairment, calcium dyshomeostasis, inhibition of long-term potentiation, apoptosis, mitochondrial damage, and cognitive decline. These cellular events include three distinct molecular mechanisms: (i) high-affinity binding with the receptors for Aβ oligomers such as N-methyl- d-aspartate receptors, cellular prion protein, nerve growth factor, insulin receptors, and frizzled receptors; (ii) the interaction of Aβ oligomers with the lipid membranes; (iii) intraneuronal accumulation of Aβ by α7-nicotinic acetylcholine receptors, apolipoprotein E, and receptor for advanced glycation end products. These studies indicate that there is a pressing need to carefully examine the role of size, appearance, and the conformation of oligomers in identifying the specific mechanism of neurotoxicity that may uncover potential targets for designing AD therapeutics.

Fluorescence Depolarization Kinetics Captures Short-Range Backbone Dihedral Rotations and Long-Range Correlated Dynamics of an Intrinsically Disordered Protein

Intrinsically disordered proteins (IDPs) do not autonomously fold into well-defined three-dimensional structures and are best described as a heterogeneous ensemble of rapidly interconverting conformers. It is challenging to elucidate their complex dynamic signatures using a single technique. In this study, we employed sensitive fluorescence depolarization kinetics by following picosecond time-resolved fluorescence anisotropy decays to directly capture the essential dynamical features of intrinsically disordered α-synuclein (α-syn) site-specifically labeled with thiol-active fluorophores. By utilizing a long-lifetime (≥10 ns) anisotropic label, we were able to discern three distinct rotational components of α-syn. The subnanosecond component represents the local wobbling-in-cone motion of the fluorophore, whereas the slower (∼1.4 ns) component corresponds to the short-range backbone dynamics governed by collective torsional fluctuations in the Ramachandran Φ-Ψ dihedral space. This backbone dihedral rotational time scale is sensitive to the local chain stiffness and slows down in the presence of an adjacent proline residue. We also observed a small-amplitude (≤10%) slower rotational correlation time (6-10 ns) that represents the long-range correlated dynamics involving a much longer segment of the polypeptide chain. These intrinsic dynamic signatures of IDPs will provide critical mechanistic underpinnings in a mosaic of biophysical phenomena involving internal friction, allosteric interactions, and phase separation.