Fluid Uptake Research Articles

Integrated experimental studies of pore structure and fluid uptake in the Bossier Shale in eastern Texas, USA

Within the Haynesville-Bossier Shale complex, the Bossier Shale has not been extensively studied by either industry and academia, despite it being an unconventional gas reservoir and a potential caprock for carbon storage in the underlaying Haynesville Shale. The lack of knowledge of the complex pore structures and fluid-rock interactions hinders the effective extraction of gas and the characterization of fluid reservoirs and sealing capacity. Integrated experimental studies of pore structure and fluid-rock interactions were conducted in seven Bossier Shale core samples collected in eastern Texas. Petrographic, geochemical, and petrophysical properties such as mineral composition, organic richness, thermal maturity, porosity, pore/pore throat diameter distribution, water-accessible pores, liquid water imbibition, and water vapor adsorption were characterized using complementary approaches of thin-section petrography, scanning electron microscopy, X-ray diffraction, total organic matter, pyrolysis, mercury intrusion porosimetry, nuclear magnetic resonance, (Ultra-) small angle X-rays scattering as well as small angle neutron scattering with deuterated liquids and contrast variation. The results show that the thermally mature Bossier Shales are composed of mixed argillaceous mudstone, mixed mudstone, and mixed carbonate mudstone. The shale contains both organic and inorganic pores, with porosities of 3.24–9.37 %, pore-to-throat ratios of 1.65 to 19.4, and water-accessible pores accounting for 28.7–72.6 % of total pores. Approaches of liquid water imbibition and water vapor adsorption, with and without direct contact of water with shale samples, indicate that liquid water first enters the nano-sized pores under high capillary pressures, and water vapor adsorption is mainly controlled by both clay minerals and pores with diameters less than 10 nm. These findings contribute to a better understanding of pore structures and water-shale interactions and their controlling factors in the Bossier Shale.

Fabrication and evaluation of four combinations of pullulan-based biopolymeric, microporous scaffolds impregnated with peppermint oil for management of partial thickness burn wounds and accelerated tissue regeneration

Burn injuries are common in both civilian and military settings and cause severe morbidity and mortality. The present study aimed to develop microporous bioactive scaffolds from the natural polysaccharide, pullulan, combined individually with Gelatin (Gel)/Alginate (Alg)/Chitosan (Ch)/Carboxy-methyl cellulose (CMC), and crosslinked with glutaraldehyde to form a polymeric network. The objective was to evaluate and compare their efficacy in healing second degree partial-thickness burn wounds. The scaffolds were also impregnated with peppermint oil (PEO) to provide potential analgesic and cooling effects. Scaffolds were characterized using FTIR, TGA and SEM analysis to understand the intra-and intermolecular interactions and morphological characteristics. In vitro parameters like fluid uptake ability, biodegradation and hemolytic index were also assessed. Biocompatibility studies, including cell adhesion, migration and proliferation, were conducted using L929 mouse fibroblast cell lines. The in vivo efficacy was evaluated in Sprague Dawley rats inflicted with second degree burns to assess and compare wound retraction across different experimental groups. Histology, immunohistochemistry along with gram and picrosirius staining studies were also performed. The average pore size of all biopolymeric scaffold combinations ranged between 25.6 and 298 μm. All four test combinations were non-hemolytic, with hemolytic indices between 0.3 and 2.9. Wound retraction studies in rats clearly indicated that among the four test combinations studied, Pu/Gel/PEO scaffold not only reduced local inflammation faster but also accelerated dermal regeneration in comparison to positive control as well as other test combinations (viz., Pu/Alg/PEO, Pu/Ch/PEO, and Pu/CMC/PEO). Immunohistochemistry results corroborated animal efficacy findings and demonstrated enhanced expression level of epidermal growth factor and fibroblast growth factor-2 in Pu/Gel/PEO scaffold treated group. Picrosirius staining also revealed enhanced collagen deposition in Pu/Gel/PEO scaffold treated group. The study findings suggest that biopolymeric scaffolds made from pullulan combined with gelatin and PEO (Pu/Gel/PEO) could serve as a promising substrate for skin regeneration template for second degree burns.

Biomechanical drivers of the evolution of butterflies and moths with a coilable proboscis.

Current biomechanical models suggest that butterflies and moths use their proboscis as a drinking straw pulling nectar as a continuous liquid column. Our analyses revealed an alternative mode for fluid uptake: drinking bubble trains that help defeat drag. We combined X-ray phase-contrast imaging, optical video microscopy, micro-computed tomography, phylogenetic models of evolution and fluid mechanics models of bubble-train formation to understand the biomechanics of butterfly and moth feeding. Our models suggest that the bubble-train mechanism appeared in the early evolution of butterflies and moths with a proboscis long enough to coil. We propose that, in addition to the ability to drink a continuous column of fluid from pools, the ability to exploit fluid films by capitalizing on bubble trains would have expanded the range of available food sources, facilitating diversification of Lepidoptera.

Electrospun Silk-ICG Composite Fibers and the Application toward Hemorrhage Control.

In trauma and surgery, efficient hemorrhage control is crucial to avert fatal blood loss and increase the likelihood of survival. There is a significant demand for novel biomaterials capable of promptly and effectively managing bleeding. This study aimed to develop flexible biocomposite fibrous scaffolds with an electrospinning technique using silk fibroin (SF) and indocyanine green (ICG). The FDA-approved ICG dye has unique photothermal properties. The water permeability, degradability, and biocompatibility of Bombyx mori cocoon-derived SF make it promising for biomedical applications. While as-spun SF-ICG fibers were dissolvable in water, ethanol vapor treatment (EVT) effectively induced secondary structural changes to promote β-sheet formation. This resulted in significantly improved aqueous stability and mechanical strength of the fibers, thereby increasing their fluid uptake capability. The enhanced SF-ICG interaction effectively prevented ICG leaching from the composite fibers, enabling them to generate heat under NIR irradiation due to ICG's photothermal properties. Our results showed that an SF-ICG 0.4% fibrous matrix can uptake 473% water. When water was replaced by bovine blood, a 25 s NIR irradiation induced complete blood coagulation. However, pure silk did not have the same effect. Additionally, NIR irradiation of the SF-ICG fibers successfully stopped the flow of blood in an in vitro model that mimicked a damaged blood vessel. This novel breakthrough offers a biotextile platform poised to enhance patient outcomes across various medical scenarios, representing a significant milestone in functional biomaterials.

The spermatheca ultrastructure of the ground beetle Clinidium canaliculatum (Costa) (Carabidae, Rhysodinae)

The ground beetle Clinidium canaliculatum is a member of Rhysodinae, a taxon with still discussed systematic position. The spermatheca of this species is a small cylindrical structure connected to the common oviduct by a thin duct. The ultrastructure of the organ has revealed that the apical receptacle is provided with an epithelium lined by a thick cuticle from the deeper region of which several finger-like cuticular structures extend into the cytoplasm. On these structures adhere microtubule bundles that cross the whole cytoplasm to anchor on short densities along the basal plasma membrane. These specializations are strongly reminiscent of the hemidesmosomes, possibly playing a mechanical role enabling the cells to resist to the muscle contractions pushing the sperm towards the spermathecal duct. The cells are rich in mitochondria and glycogen granules and they are possibly involved in fluid uptake from the spermathecal lumen. The spermathecal duct has a simple epithelium lined by a soft cuticle. The sperm present in the apical receptacle and in the duct lumen maintain the structure described in the male genital apparatuses. They are generally free and embedded in a homogeneous electron-dense material. Occasionally, a sperm bundle, still with an apical cap, was visible in the spermathecal receptacle.

Cellular Uptake of Phase-Separating Peptide Coacervates.

Peptide coacervates self-assembling via liquid-liquid phase separation are appealing intracellular delivery vehicles of macromolecular therapeutics (proteins, DNA, mRNA) owing to their non-cytotoxicity, high encapsulation capacity, and efficient cellular uptake. However, the mechanisms by which these viscoelastic droplets cross the cellular membranes remain unknown. Here, using multimodal imaging, data analytics, and biochemical inhibition assays, we identify the key steps by which droplets enter the cell. We find that the uptake follows a non-canonical pathway and instead integrates essential features of macropinocytosis and phagocytosis, namely active remodeling of the actin cytoskeleton and appearance of filopodia-like protrusions. Experiments using giant unilamellar vesicles show that the coacervates attach to the bounding membrane in a charge- and cholesterol-dependent manner but do not breach the lipid bilayer barrier. Cell uptake in the presence of small molecule inhibitors - interfering with actin and tubulin polymerization - confirm the active role of cytoskeleton remodeling, most prominently evident in electron microscopy imaging. These findings suggest a peculiar internalization mechanism for viscoelastic, glassy coacervate droplets combining features of non-specific uptake of fluids by macropinocytosis and particulate uptake of phagocytosis. The broad implications of this study will enable to enhance the efficacy and utility of coacervate-based strategies for intracellular delivery of macromolecular therapeutics.

Improving water management in gas diffusion layers through the optimization of carbon composite microporous layers

Using the Washburn method, the wettability of microporous layer (MPL)-coated carbon-felt gas diffusion layers (GDLs) with liquids with different polarities were studied using process tensiometry. The Washburn approach allows us to study fluid uptake into the electrode pores through capillarity and the resulting liquid-solid internal contact angles. Interpretation using the Owens-Wendt analysis reveals the effects of varying proportions of hydrophobic poly(tetrafluoroethylene) (PTFE) and multi-walled carbon nanotubes (MWCNTs) in the MPL yielding solid-vapor surface energies. An optimal MPL contained a 10 wt% MWCNT/KJB carbon substrate and 10 wt% PTFE loading. This information was corroborated by evaluating these materials in anion exchange membrane fuel cells with simultaneous gas and aqueous electrolyte feed.

Characteristics of environmental stress cracking of PE-HD induced by biodiesel and diesel fuels

In the context of the increasing effect of carbon dioxide emissions on the global climate biodiesel produced from renewable sources has emerged as a promising contender replacing fossil fuels, especially in long-range transport vehicles, using existing engines and infrastructure.High-density polyethylene is one of the prevailing materials for pipe and container applications for storage and transport of such fuels, both, from fossil and renewable resources. The contact with the respective fuels raises questions concerning material compatibility as biodiesel exhibits significant differences compared to conventional diesel fuel affecting its sorption and plasticization behavior in polyethylene. In this study, its behavior with respect to environmental stress cracking, considered one of the most frequent damage mechanisms leading to failure of polymer parts and packaging, was evaluated using the well-established Full Notch Creep Test. This approach allows for a detailed fracture surface analysis using imaging techniques, such as optical and laser scanning microscopy, as well as infrared spectroscopy. Comparing the environmental stress cracking behavior in standard surfactant solutions with that in biodiesel and diesel, respective crack propagation rates, showing different levels of acceleration, were determined and details of the underlying mechanisms could be revealed. Furthermore, the specific infrared absorption of the biodiesel's ester functionality allows its semi-quantitative determination on the fracture surface of the tested specimens after failure. Thus, a preferred uptake of sorptive fluids in the fracture zone due to local morphological changes of the polyethylene could be directly evidenced by infrared spectroscopy.

Mannose receptor (MRC1) mediates uptake of dextran in macrophages via receptor-mediated endocytosis.

Macrophages constantly survey and clear tissues by specifically and non-specifically internalizing debris and solutes. However, the molecular mechanisms and modes of regulation of these endocytic and macropinocytic processes are not well understood. Here, CRISPR/Cas9 whole genome screens were used to identify genes regulating uptake of dextran, a sugar polymer that is frequently used as a marker macropinocytosis, and compared with Lucifer yellow, a fluorescent dye with no known receptors. The authors identified the mannose receptor as well as other proteins regulating expression of the mannose receptor as top hits in the screen. Targeted disruption of Mrc1 , the gene that encodes mannose receptor, greatly diminished dextran uptake but had no effect on cellular uptake of Lucifer yellow. Furthermore, exposure to the cytokine IL4 upregulated mannose receptor expression on the cell surface and increased uptake of dextran with little effect on Lucifer yellow uptake. Studies seeking to understand regulation of macropinocytosis in macrophages will be confounded by the use of dextran as a fluid-phase marker. MRC1 is a marker of alternatively activated/anti-inflammatory macrophages and is a potential target for delivery of therapeutics to macrophages. This work provides the basis for mechanistic underpinning of how MRC1 contributes to the receptor-mediated uptake of carbohydrates and glycoproteins from the tissue milieu and distinguishes genes regulating receptor-mediated endocytosis from those regulating the bona fide fluid-phase uptake of fluids and solutes by macropinocytosis.

A conserved regulation of cell expansion underlies notochord mechanics, spine morphogenesis, and endochondral bone lengthening.

Cell size is a key contributor to tissue morphogenesis 1 . As a notable example, growth plate hypertrophic chondrocytes use cellular biogenesis and disproportionate fluid uptake to expand 10-20 times in size to drive lengthening of endochondral bone 2,3 . Similarly, notochordal cells expand to one of the largest cell types in the developing embryo to drive axial extension 4-6 . In zebrafish, the notochord vacuolated cells undergo vacuole fusion to form a single large, fluid-filled vacuole that fills the cytoplasmic space and contributes to vacuolated cell expansion 7 . When this process goes awry, the notochord lacks sufficient hydrostatic pressure to support vertebral bone deposition resulting in adult spines with misshapen vertebral bones and scoliosis 8 . However, it remains unclear whether endochondral bone and the notochord share common genetic and cellular mechanisms for regulating cell and tissue expansion. Here, we demonstrate that the 5'-inositol phosphatase gene, inppl1a , regulates notochord expansion, spine morphogenesis, and endochondral bone lengthening in zebrafish. Furthermore, we show that inppl1a regulates notochord expansion independent of vacuole fusion, thereby genetically decoupling these processes. We demonstrate that inppl1a -dependent notochord expansion is essential to establish normal mechanical properties of the notochord to facilitate the development of a straight spine. Finally, we find that inppl1a is also important for endochondral bone lengthening in fish, as has been shown in the human INPPL1 -related endochondral bone disorder, Opsismodysplasia 9 . Overall, this work reveals a conserved mechanism of cell size regulation that influences disparate tissues critical for skeletal development and short-stature disorders.

In Situ Hydrogel-Forming Powders Containing Eutectic Mixture of Curcumin-Arginine as a Multi-Drug Delivery System for Wound Healing Applications

Background: Curcumin (CUR) has antimicrobial, anti-inflammatory, and antioxidant bioactivities and is a promising molecule to treat chronic wounds. However, CUR shows limited oral bioavailability due to low aqueous solubility and dissolution, chemical instability, and rapid metabolism in the gastrointestinal tract and liver. Therefore, topical delivery seems to provide therapeutic concentrations of CUR in a controlled manner. Arginine (ARG) promotes the wound healing process. CUR and ARG form a eutectic mixture (EMCA) that can be used for simultaneous improvement of dissolution of CUR and combinational wound therapy. Here, we have formulated in situ hydrogel-forming powders of EMCA using hydrophilic carriers. Methods: EMCA was prepared by liquid-assisted grinding and analyzed by powder X-ray diffraction (PXRD) and Fourier transform infrared (FT-IR) methods. The formulations were prepared by mixing EMCA with sodium carboxy methyl cellulose, sodium alginate, and polyethylene glycol. Optical microscopy, flow property, dissolution rate, water uptake, hydrogel forming ability, release profile, and antioxidant activity of the formulated powders were measured and compared with raw CUR. Results: The solid-state analyses revealed the formation of EMCA. Photographs showed that EMCA exhibited a lower particle size than raw CUR and ARG. The formulation content significantly affected fluid uptake, hydrogel-forming ability, and dissolution rate. The optimized formulation (FEP5) showed a considerable enhancement in the dissolution rate of CUR and could control the release. FEP5 also demonstrated promising characteristics including high fluid uptake and suitable hydrogel-forming ability. FEP5 enhanced the antioxidant activity of CUR from 9% to 50%. Additionally, FEP5 exhibited improved flow properties compared to raw CUR, which is crucial for practical applications in wound therapy. Conclusion: Current work highlighted the potential of EMCA formulated as a hydrogel-forming powder as a novel formulation with improved dissolution, rapid fluid uptake, inexpensive components, feasible method of preparation, and easy application and removal for combinational wound therapy

Preparation and characterization of amidated pectin-gelatin-oxidized tannic acid hydrogel films supplemented with in-situ reduced silver nanoparticles for wound-dressing applications

Wound dressings play a crucial role in protecting injured tissues and promoting the healing process. Traditional fabrication of antibacterial wound dressings can be complex and may involve toxic components. In this study, we developed an innovative hydrogel film (AP:GE@OTA/Ag) composed of amidated pectin (AP), gelatin (GE), oxidized tannic acid (OTA) at varying concentrations, and in-situ reduced silver nanoparticles (AgNPs). FTIR and XRD analyses confirmed that crosslinking occurs via interactions between OTA quinone groups and free amino groups in AP and GE. TEM imaging demonstrated the well-dispersed AgNPs with an average particle size of 58.64 nm, while the TG measurements indicated the enhancement of the thermal stability compared to AP:GE films. The AP:GE@OTA/Ag films exhibited superior fluid uptake ability (90.96 % at 2 h), water retention capacity (91.69 % at 2 h), and water vapor transmission rate (1903.29 g/m2/day), alongside improved tensile strength (38 MPa). Additionally, these films showed excellent cytocompatibility and sustained potent antimicrobial activity against S. aureus and E. coli with low AgNPs loadings of 1.02 ± 0.13 μg/cm2. NIT-1 mouse insulinoma cells demonstrated robust proliferation when cultured with the prepared dressings. These films significantly accelerated wound repair in a skin excision model, indicating their potential clinical applications for wound healing.

Leep2A and Leep2B function as a RasGAP complex to regulate macropinosome formation.

Macropinocytosis mediates the non-selective bulk uptake of extracellular fluid, enabling cells to survey the environment and obtain nutrients. A conserved set of signaling proteins orchestrates the actin dynamics that lead to membrane ruffling and macropinosome formation across various eukaryotic organisms. At the center of this signaling network are Ras GTPases, whose activation potently stimulates macropinocytosis. However, how Ras signaling is initiated and spatiotemporally regulated during macropinocytosis is not well understood. By using the model system Dictyostelium and a proteomics-based approach to identify regulators of macropinocytosis, we uncovered Leep2, consisting of Leep2A and Leep2B, as a RasGAP complex. The Leep2 complex specifically localizes to emerging macropinocytic cups and nascent macropinosomes, where it modulates macropinosome formation by regulating the activities of three Ras family small GTPases. Deletion or overexpression of the complex, as well as disruption or sustained activation of the target Ras GTPases, impairs macropinocytic activity. Our data reveal the critical role of fine-tuning Ras activity in directing macropinosome formation.

Feeding rate in adult Manduca sexta is unaffected by proboscis submersion depth.

Adult moths from framily Spingidae (i.e. hawkmoths or sphinx moths) commonly feed on flower nectar through an extended proboscis, often several centimeters in length and longer than the body of the moth. Feeding on a viscous liquid (nectar) through a long and narrow tube is a challenging fluid dynamic problem and the subject of long-running scientific investigation. Here we characterized the relationship between proboscis submergence depth and nectar drinking rate in Manduca sexta hawkmoths. Video recordings of moth feeding bouts were collected and neural networks were used to extract data by object localization, tracking the location of the nectar meniscus and moths' proboscis tips. We found that although feeding rates vary among bouts, the variation was not associated with proboscis submergence depth. These results show that despite the theoretical possibility of fluid uptake through the walls of the proboscis, such effects do not have a substantial effect on nectar uptake rate, and suggest that nectar must traverse the full length of the proboscis.

Meningeal lymphatic CGRP signaling governs pain via cerebrospinal fluid efflux and neuroinflammation in migraine models.

Recently developed antimigraine therapeutics targeting calcitonin gene-related peptide (CGRP) signaling are effective, though their sites of activity remain elusive. Notably, the lymphatic vasculature is responsive to CGRP signaling, but whether meningeal lymphatic vessels (MLVs) contribute to migraine pathophysiology is unknown. Mice with lymphatic vasculature deficient in the CGRP receptor (CalcrliLEC mice) treated with nitroglycerin-mediated (NTG-mediated) chronic migraine exhibit reduced pain and light avoidance compared with NTG-treated littermate controls. Gene expression profiles of lymphatic endothelial cells (LECs) isolated from the meninges of Rpl22HA/+;Lyve1Cre RiboTag mice treated with NTG revealed increased MLV-immune interactions compared with cells from untreated mice. Interestingly, the relative abundance of mucosal vascular addressin cell adhesion molecule 1-interacting (MAdCAM1-interacting) CD4+ T cells was increased in the deep cervical lymph nodes of NTG-treated control mice but not in NTG-treated CalcrliLEC mice. Treatment of cultured hLECs with CGRP peptide in vitro induced vascular endothelial-cadherin (VE-cadherin) rearrangement and reduced functional permeability. Likewise, intra cisterna magna injection of CGRP caused rearrangement of VE-cadherin, decreased MLV uptake of cerebrospinal fluid (CSF), and impaired CSF drainage in control mice but not in CalcrliLEC mice. Collectively, these findings reveal a previously unrecognized role for lymphatics in chronic migraine, whereby CGRP signaling primes MLV-immune interactions and reduces CSF efflux.

Physicochemical and biological characterization of propolis-loaded composite polyamide-6/soybean protein nanofibers for wound healing applications

Dressings are pivotal in aiding wound recovery, yet they are burdened by significant constraints. In addition to possessing antibacterial properties, the effectiveness of a wound dressing must be rigorously assessed for its potential utility across diverse medical applications. Propolis (Pro) is widely acknowledged for its antioxidant, antibacterial, and anti-inflammatory properties, positioning it as a promising candidate for wound healing and tissue engineering applications. This study presents a novel composite nanofiber (NF) material comprising polyamide-6 (PA6) and soybean protein as matrix components, incorporating Pro as a payload. We aimed to mimic the extracellular matrix, thus promotion the proliferation and adhesion of mouse embryonic fibroblast cells (NIH3T3) on the scaffold's surface. The morphology and composition of the NFs, examined through scanning electron microscopy (SEM) imaging and Fourier-transform infrared (FTIR) spectroscopy. The Pro-loaded fibers exhibited diameters ranging from 102 to 270 nm. Notably, the NFs demonstrated a dose-dependent increase in porosity, water vapor transmission rate, and fluid uptake capacity. However, the hydrophilic categorized nanofibers (NFs) did not exhibit a concentration-dependent effect on contact angle measurements. After a 15-day period, the Pro-loaded fibers experienced degradation within the range of 39–53 %. Using UV–visible spectrophotometry, the amount of pro released was measured. The rates of release were found to be 29.93 %, 41.02 %, and 60.06 % within 24 h for PA6/Soy/Pro5 %, PA6/Soy/Pro10 %, and PA6/Soy/Pro20 % NFs, respectively. Importantly, our study showcased the significant inhibitory effects of Pro-loaded fibers on the growth of E. coli and S. aureus, with inhibition increasing proportionally with higher Pro concentrations. This observation underscores the potential of Pro-based composite NFs as effective antimicrobial agents for wound dressings and tissue scaffolds. Furthermore, the biocompatibility of the fabricated nanofibrous mats was confirmed through the MTT test, affirming the non-toxic nature of all formulations. SEM imaging further demonstrated the optimal adhesion of cells on the NFs, confirming the findings of the MTT test and highlighting the suitability of Pro-loaded NFs for cell attachment and proliferation.

Experimental study on reinjection enhancement of sandstone with radial wells

Geothermal resources are abundant and can be vigorously developed. Vertical well reinjection is widely used in sandstone geothermal resources, but the efficiency is low due to near-well blockage. There is a lack of existing measures to improve reinjection efficiency. For sandstone reservoirs, a new method using radial well technology is proposed to enhance reinjection efficiency. Firstly, based on similarity criteria and non-dimensional analysis, the main experiment parameters and materials are determined. Secondly, a geothermal reinjection enhancement experiment system is constructed. Finally, reinjection experiments are conducted with radial well branch number, layer number, and phase angle to explore the impact of each parameter on reinjection efficiency. Results indicate that, in comparison to vertical well, radial wells can markedly increase the total fluid uptake. The maximum reinjection enhancements of radial wells is 90.49 %. The pressure drop coefficients can reach a minimum of 0.025. Within the same radial well type, the total fluid uptake shows an overall rising trend with an increase in the number of branch wells. Compared to single-layer radial wells, double-layer radial wells demonstrate better overall reinjection efficiency. Additionally, when comparing double-layer parallel and double-layer intersecting radial wells, the latter exhibits a more advantageous overall reinjection enhancement. The study suggests that radial wells can alleviate near-wellbore clogging, significantly increase reinjection capacity in sandstone reservoirs, and provide an effective technical approach and experiment evidence for efficient reinjection development in sandstone.

Modulation of infectious Salmon Anaemia virus infection by clathrin-mediated endocytosis and macropinocytosis inhibitors

Infectious salmon anaemia virus (ISAV) is a pathogen that causes disease and large mortality in farm-raised Salmo salar L., being considered as a major problem in the salmon industry. However, despite its relevance, there are still numerous knowledge gaps on virus entry and early stages of infection. Previous studies suggested that virus entry into cells occurs via endocytosis, with no description of specific mechanisms. However, it remains unknown if the endocytosis induced by ISAV is a clathrin-dependent or clathrin-independent process. This study aimed to identify cellular mechanisms allowing ISAV entry into Atlantic Salmon head kidney (ASK) cells. Our results showed that ISAV can be found in coated pits and membrane ruffles, the latter being induced by a rearrangement of actin filaments promoted by ISAV infection. Additionally, it was determined that ISAV stimulate the uptake of extracellular fluid in a multiplicity of infection (MOI)-dependent manner. When the clathrin-mediated endocytic pathway was pharmacologically inhibited, ISAV infection was significantly reduced but not entirely inhibited. Similarly, when the Na+/H+ exchanger (NHE), a key component of macropinocytosis, was inhibited, ISAV infection was negatively affected. Our results suggest that ISAV enters cells via both clathrin-mediated endocytosis and most likely macropinocytosis.

A transcription factor complex in Dictyostelium enables adaptive changes in macropinocytosis during the growth-to-development transition

Macropinocytosis, an evolutionarily conserved endocytic pathway, mediates nonselective bulk uptake of extracellular fluid. It is the primary route for axenic Dictyostelium cells to obtain nutrients and has also emerged as a nutrient-scavenging pathway for mammalian cells. How cells adjust macropinocytic activity in various physiological or developmental contexts remains to be elucidated. We discovered that, in Dictyostelium cells, the transcription factors Hbx5 and MybG form a functional complex in the nucleus to maintain macropinocytic activity during the growth stage. In contrast, during starvation-induced multicellular development, the transcription factor complex undergoes nucleocytoplasmic shuttling in response to oscillatory cyclic adenosine 3',5'-monophosphate (cAMP) signals, which leads to increased cytoplasmic retention of the complex and progressive downregulation of macropinocytosis. Therefore, by coupling macropinocytosis-related gene expression to the cAMP oscillation system, which facilitates long-range cell-cell communication, the dynamic translocation of the Hbx5-MybG complex orchestrates a population-level adjustment of macropinocytic activity to adapt to changing environmental conditions.

Circumventing the Gastrointestinal Barrier for Oral Delivery of Therapeutic Proteins and Peptides (PPTs): Current Trends and Future Trajectories.

Therapeutic proteins and peptides (PPTs) have become one of the most important biological molecules for the management of many common and complex diseases due to their high specificity and high bioactivity. However, these biomolecules are mainly given by the hypodermic injection, which often leads to poor patient compliance due to the invasive nature of this route of administration. The oral route has been considered the most convenient and patient-friendly route for drug delivery relative to hypodermic injection. Despite the ease and simplicity conferred by oral administration, this drug delivery route suffers rapid peptide degradation in gastric fluid and low intestinal uptake. In order to circumvent these issues, several strategies, such as enzyme inhibitors, permeation enhancers, chemical modification, mucoadhesive and stimuli-responsive polymers, and specialised particulate formulation have been developed. Such strategies are designed with the aim of protecting proteins and peptides from the harsh gastrointestinal environment as well as providing a strategy to enhance the uptake of the therapeutic across the gastrointestinal tract. This review aims to provide an overview of the current development in enteral drug delivery strategies for proteins and peptides. The design of these drug delivery systems in overcoming physical and chemical barriers along the gastrointestinal tract while improving oral bioavailability will be highlighted and discussed.