Elevated Hydrostatic Pressure Research Articles

The deeper the rounder: body shape variation in lice parasitizing diving hosts

Seal lice, unique among insects, show remarkable adaptability to the extreme conditions of the deep sea. Evolving with their seal and sea lion hosts, they have managed to tolerate hypoxia, high salinity, low temperature, and elevated hydrostatic pressure. Given the diving capabilities of their mammalian hosts, which can reach depths of hundreds to thousands of meters, our study examines the morphological variation among closely related seal lice species infesting hosts with different maximum diving depths. In particular, our research reveals a significant morphological difference between lice associated with regular and deep-diving hosts, where lice from deep-diving hosts tend to be rounder. This could be an adaptation to withstand the high hydrostatic pressures found in the deep ocean. The rounded shape optimizes the louse’s ability to withstand external pressure by redistributing it over a larger ventral/dorsal plane. This in turn minimizes the internal energy required to support body deformations, thereby increasing the louse’s resilience in the deep sea environment.

Effects of Thermally-Assisted and High-Pressure Processing on Background Microbiota and the Listeria monocytogenes Load of a Minimally Processed Commodity.

The current study investigated the impact of treatments with elevated hydrostatic pressure (500 MPa) for inactivation of Listeria monocytogenes on smoked rainbow trout (Oncorhynchus mykiss) at high and low inoculation levels. The temperature values of the trials were set at 4.4 and 60.0 °C, adjusted with a circulating water bath connected to a stainless steel jacket surrounding the pressure processing chamber. Before pressure processing, the counts (selective counts of PALCAM, mean ± SD) of L. monocytogenes were 6.45 ± 0.1 log CFU/g and were reduced (p < 0.05) to 3.72 ± 0.3, and <1.48 ± 0.8 log CFU/g after 10 min of treatment at 4.4 and 60.0 °C, respectively. Treatments of low inoculation level samples were similarly efficacious and resulted in a reduction (p < 0.05) of the pathogen to 1.62 ± 0.3 and <0.82 ± 0.0 log CFU/g for treatments at 4.4 and 60.0 °C, respectively. At 4.4 °C, linear D-value and non-linear kmax1 were 8.68 and 0.50, and 5.81 and 2.41 for high-inoculation and low-inoculation samples, respectively. Application of hydrostatic pressure at 500 MPa at cold and elevated temperatures was efficacious for up to 5.03 log CFU/g reduction of L. monocytogenes, illustrating the potential for further adaptation of this technology.

Organic matter degradation in the deep, sulfidic waters of the Black Sea: insights into the ecophysiology of novel anaerobic bacteria

BackgroundRecent studies have reported the identity and functions of key anaerobes involved in the degradation of organic matter (OM) in deep (> 1000 m) sulfidic marine habitats. However, due to the lack of available isolates, detailed investigation of their physiology has been precluded. In this study, we cultivated and characterized the ecophysiology of a wide range of novel anaerobes potentially involved in OM degradation in deep (2000 m depth) sulfidic waters of the Black Sea.ResultsWe have successfully cultivated a diverse group of novel anaerobes belonging to various phyla, including Fusobacteriota (strain S5), Bacillota (strains A1T and A2), Spirochaetota (strains M1T, M2, and S2), Bacteroidota (strains B1T, B2, S6, L6, SYP, and M2P), Cloacimonadota (Cloa-SY6), Planctomycetota (Plnct-SY6), Mycoplasmatota (Izemo-BS), Chloroflexota (Chflx-SY6), and Desulfobacterota (strains S3T and S3-i). These microorganisms were able to grow at an elevated hydrostatic pressure of up to 50 MPa.Moreover, this study revealed that different anaerobes were specialized in degrading specific types of OM. Strains affiliated with the phyla Fusobacteriota, Bacillota, Planctomycetota, and Mycoplasmatota were found to be specialized in the degradation of cellulose, cellobiose, chitin, and DNA, respectively, while strains affiliated with Spirochaetota, Bacteroidota, Cloacimonadota, and Chloroflexota preferred to ferment less complex forms of OM. We also identified members of the phylum Desulfobacterota as terminal oxidizers, potentially involved in the consumption of hydrogen produced during fermentation. These results were supported by the identification of genes in the (meta)genomes of the cultivated microbial taxa which encode proteins of specific metabolic pathways. Additionally, we analyzed the composition of membrane lipids of selected taxa, which could be critical for their survival in the harsh environment of the deep sulfidic waters and could potentially be used as biosignatures for these strains in the sulfidic waters of the Black Sea.ConclusionsThis is the first report that demonstrates the cultivation and ecophysiology of such a diverse group of microorganisms from any sulfidic marine habitat. Collectively, this study provides a step forward in our understanding of the microbes thriving in the extreme conditions of the deep sulfidic waters of the Black Sea.Exyq52VguUrmavAnxe2qURVideo

Hydrostatic pressure mediates epithelial-mesenchymal transition of cholangiocytes through RhoA/ROCK and TGF-β/smad pathways.

Biomechanical cue within the tissue microenvironment is known to play a critical role in regulating cell behaviors and maintaining tissue homeostasis. As hydrostatic pressure often increases in biliary system under pathological states, we investigated the effect of the moderate elevation of the hydrostatic pressure on biliary epithelial cells, especially on the epithelial-mesenchymal transition (EMT). Human intrahepatic biliary epithelial cells were loaded to hydrostatic pressure using a commercial device. We found that loading the cells to 50 mmHg hydrostatic pressure induced obvious morphological changes and significantly upregulated vimentin, ZEB1, and pSmad2/3, fibronectin, and collagen 1α. All changes induced by hydrostatic pressure loading were effectively mitigated by either ROCK inhibitor (Y-27632) or ALK5 inhibitor (SB-431542). Our in vitro experimental data suggests that hydrostatic pressure loading induces EMT of cholangiocytes through RhoA/ROCK and TGF-β/Smad pathways. Elevated hydrostatic pressure in biliary duct system under pathological states may promote the biliary epithelial cells shifting to profibrotic and mesenchymal characteristics.

Elevated hydrostatic pressure enhances the potential for microbially mediated carbon sequestration at the sediment–water interface in a deep-water reservoir by modulating functional genes and metabolic pathways

Microbially mediated carbon cycling is essential for the production of refractory dissolved organic carbon and subsequent formation of stable carbon sinks at the sediment–water interface (SWI) in aquatic ecosystems, such as lakes. It remains unclear how this process is influenced by hydrostatic pressure changes due to water level fluctuation in deep-water reservoirs. Here, a microcosm simulation experiment was carried out to decipher the response of microbially mediated carbon cycling to various hydrostatic pressures (i.e., 0.1 MPa [atmospheric pressure], 0.2 MPa, 0.5 MPa, 0.7 MPa) at the SWI in Jinpen Reservoir, Shaanxi Province, China. The response mechanisms of microbial community structure, functional gene abundance, and metabolic pathway activity associated with carbon cycling were explored by metagenomics and metabolomics. Results showed that the number of microbial species in sediment samples increased with elevating pressure. The relative abundance of archaea also increased from 0.2% to 0.4% as a consequence of pressure elevation, accompanied by 0.17% and 0.03% decrease in bacteria and fungi, respectively. In contrast with low pressures, high pressures allowed the microbial communities to form a more closely connected network, which maintained more complex interspecies interactions and greater system stability. High pressures additionally improved the abundances of specific functional genes (e.g., ALDO, ACO, sdhA, and sdhC) in carbon metabolic pathways, promoted carbon fixation by the reductive pentose phosphate (Calvin) and citrate cycles, and hindered methanogenesis. Piezophilic taxa (e.g., Gammaproteobacteria, Alphaproteobacteria, Bacteroidetes) and genes (e.g., ompH, asd) were identified among carbon cycling-associated microbial communities. The piezophilic genes, which were mainly present in the Proteobacteria phylum, increased first and then decreased in abundance with elevating pressure. The findings indicate that elevated hydrostatic pressure contributes to carbon sequestration at the SWI in deep-water reservoirs by changing carbon cycling-associated microbial species, as well as relevant functional genes and metabolic pathways.Graphical

Impact of Temperature on the Performance of Plasma-Pulse Geo-Drilling (PPGD)

Advanced Geothermal Systems (AGS) may in principle be able to satisfy the global energy demand using standard continental-crust geothermal temperature gradients of 25–35 ∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}C/km. However, conventional mechanical rotary drilling is still too expensive to cost-competitively provide the required borehole depths and lengths for AGS. This highlights the need for a new, cheaper drilling technology, such as Plasma-Pulse Geo-Drilling (PPGD), to improve the economic feasibility of AGS. PPGD is a rather new drilling method and is based on nanoseconds-long, high-voltage pulses to fracture the rock without mechanical abrasion. The absence of mechanical abrasion prolongs the bit lifetime, thereby increasing the penetration rate. Laboratory experiments under ambient-air conditions and comparative analyses (which assume drilling at a depth between 3.5 and 4.5 km) have shown that PPGD may reduce drilling costs by approximately 17–23%, compared to the costs of mechanical drilling, while further research and development are expected to reduce PPGD costs further. However, the performance of the PPGD process under deep wellbore conditions, i.e., at elevated temperatures as well as elevated lithostatic and hydrostatic pressures, has yet to be systematically tested. In this paper, we introduce a standard experiment parameter to examine the impact of deep wellbore conditions on PPGD performance, namely the productivity (the excavated rock volume per pulse) and the specific energy (the amount of energy required to drill a unit volume of rock). We employ these parameters to investigate the effect of temperature on PPGD performance, with temperatures increasing up to 80 ∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}C, corresponding to a drilling depth of up to approximately 3 km.

Portal hypertension in patients with nonalcoholic fatty liver disease: Current knowledge and challenges.

Portal hypertension (PH) has traditionally been observed as a consequence of significant fibrosis and cirrhosis in advanced non-alcoholic fatty liver disease (NAFLD). However, recent studies have provided evidence that PH may develop in earlier stages of NAFLD, suggesting that there are additional pathogenetic mechanisms at work in addition to liver fibrosis. The early development of PH in NAFLD is associated with hepatocellular lipid accumulation and ballooning, leading to the compression of liver sinusoids. External compression and intra-luminal obstacles cause mechanical forces such as strain, shear stress and elevated hydrostatic pressure that in turn activate mechanotransduction pathways, resulting in endothelial dysfunction and the development of fibrosis. The spatial distribution of histological and functional changes in the periportal and perisinusoidal areas of the liver lobule are considered responsible for the pre-sinusoidal component of PH in patients with NAFLD. Thus, current diagnostic methods such as hepatic venous pressure gradient (HVPG) measurement tend to underestimate portal pressure (PP) in NAFLD patients, who might decompensate below the HVPG threshold of 10 mmHg, which is traditionally considered the most relevant indicator of clinically significant portal hypertension (CSPH). This creates further challenges in finding a reliable diagnostic method to stratify the prognostic risk in this population of patients. In theory, the measurement of the portal pressure gradient guided by endoscopic ultrasound might overcome the limitations of HVPG measurement by avoiding the influence of the pre-sinusoidal component, but more investigations are needed to test its clinical utility for this indication. Liver and spleen stiffness measurement in combination with platelet count is currently the best-validated non-invasive approach for diagnosing CSPH and varices needing treatment. Lifestyle change remains the cornerstone of the treatment of PH in NAFLD, together with correcting the components of metabolic syndrome, using nonselective beta blockers, whereas emerging candidate drugs require more robust confirmation from clinical trials.

Enhancing Maternal Health: Cost-effective Alternatives in High Pressure Processing of Fruit Products

The search for efficacious Alternatives to the Current Standard Procedure in the Food Manufacturing Industry is a public health imperative. Recent advances and rapid adoption of high-pressure processing units in food manufacturing is gaining momentum across various industry sectors. The momentum of industrial importance across various sectors of food manufacturing, has led to requiring extensive microbiological hurdle validation studies for efficacious and feasible utilization of the technology. Fruit juices such as apple juice are an important component of maternal and child health diets. In regards to, microorganisms moving through vertical and horizontal gene transfer mechanisms, these systems work in the prevention of natural and anthropogenic pathogens of public health concern. As a result, adapting High Pressure Processing (HPP) in the inactivation of the pathogens is important. In this study, the protocol involves exposure to various times and intensity levels of elevated hydrostatic pressure. HPP is being used to identify the most effective conditions for vector (microorganism) inactivation. There was a large area of effectiveness of the HPP technology eradicating microorganisms in toxin-producing Escherichia coli O157:H7 (STEC), Non-O157 Shiga toxin-producing Escherichia coli (nSTEC), Salmonella serovars, and Listeria monocytogenes. Each were effectively eradicated utilizing this HPP technology. These specific microorganisms were selected as they are some of the most common ones that are involved in foodborne illness. Elevated hydrostatic pressure is a non-thermal procedure that exposes pathogens to pressures of up to 80,000 PSI (&gt;550 MPa). Various times (3, 4, and 5 minutes) at pressure intensity levels of 600 MPa, (87K PSI), 550 MPa (79K PSI), 480 MPa (70K PSI), 415 MPa (60K PSI), and 345 MPa (50K PSI) of elevated hydrostatic pressure were investigated at 4°C and for 45°C. This research measured the effect of HPP treatment in eradicating the microbial load with nominal effects on organoleptic and nutritional quality of fruit juices. The results of this study provide support of cost effective and healthy fruit juice options to mothers and their children.

Illuminating a bacterial adaptation mechanism: Infrared-driven cell division in deep-sea hydrothermal vent environments

&lt;p&gt;Based on Planck's black-body radiation law, deep-sea hydrothermal vent chimneys emit light, predominantly infrared light, which potentially supports bacterial photosynthesis in this ecosystem independently of the solar energy. To investigate the impact of this geothermal light on bacterial growth, we collected samples from the Southwest Indian Ridge and demonstrated that infrared light alone promotes bacterial growth and alters population composition. The mechanism of infrared stimulated growth was analyzed by monitoring cell wall synthesis using the &lt;i&gt;Tepidibacter hydrothermalis&lt;/i&gt; strain SWIR-1, which was isolated from cultures enriched through infrared irradiation. The results showed that the elevated hydrostatic pressure inhibited septal peptidoglycan synthesis and cell division, but had less effect on cell elongation, chromosome replication and segregation. The dominant cell shape was filaments with some swelling and inertness in cell wall synthesis depending on the level of pressure applied. Interestingly, irradiation with 880 nm infrared light effectively initiated septal synthesis and alleviated the obstruction. This revelation uncovers a novel adaptation mechanism involving infrared light for bacteria dwelling in deep-sea environments, and sheds light on the potential of infrared-mediated photobiomodulation.&lt;/p&gt;

Seismic reflection characteristics and controlling factors of shallow gas in the alongshore mud clinoform of the East China Sea

This study aims to investigate seismic reflection characteristics and controlling factors of gas within the East China Sea clinoform based on seismic profiles and borehole core data, including organic geochemistry and lithology. The seismic profiles reveal distinct gas-related seismic reflection characteristics along the coast, extending from the Yangtze Estuary southward to the elongated inner shelf. In the northern region, specifically the northern part off the Yangtze Estuary, widespread acoustic blanking is topped by a shallow gas front reflector parallel to seabed. In the middle region, spanning the southern part off the Yangtze Estuary and the adjacent northern inner shelf, widespread acoustic blanking is topped by a gas front reflector following the clinoform stratigraphy. In the southern region, off the Oujiang Estuary, there are widespread acoustic turbidities that are topped by a severely undulated gas front reflector. Based on the combined seismic-core data, it is suggested that the seismic reflection in the northern region, characterized by the gas front reflector parallel to the seabed, is controlled by the combination of anaerobic oxidation of methane and active gas diffusion triggered by seabed erosion. In the middle region, the obstructive effects of clinoform stratification on gas diffusion contribute to the seismic reflection characterized by the gas front reflector following the clinoform stratigraphy. In the southern region, the seismic reflection of low-concentration gas characterized by widespread acoustic turbidities is primarily influenced by the interplay between abundant gas source supplies due to the clinoform depocenter and elevated hydrostatic pressure in deeper water conditions. Furthermore, local gas seepage is observed in the northern region, likely due to seabed erosion and lower hydrostatic pressure in coastal zones. Additionally, the coastal zones and seaward slope break sites along the rest of the clinoform sections are also identified as having higher potentials for gas seepage.

Moisture absorption of an aerogel-based coating system under different wetting scenarios

Aerogel-based coating mortars (ACM-systems) provide energy-efficient retrofitting solutions for masonry buildings, with thermal conductivities (30–50 mW/(m·K)) comparable to traditional insulation materials. However, limited knowledge on their moisture absorption under rainwater wetting hinders the moisture-safe design of building envelopes incorporating these mortars. Thus, this study investigated the moisture absorption of an ACM-system under three laboratory-created wetting scenarios. A small-scale setup was developed to simulate runoff wetting based on typical wind-driven rain intensities in Sweden, enabling continuous monitoring of moisture conditions during wetting and drying. Two complementary capillary suction experiments under zero (free suction) and elevated hydrostatic pressure explored additional wetting scenarios. The impact of water-repellent paint and surface cracks was also assessed, as previous testing focused on undamaged ACM-systems. Among the three wetting scenarios, runoff wetting resulted in the lowest moisture absorption by the undamaged ACM-system. Water-repellent paint (sd = 0.01 m) reduced moisture uptake by up to 15% during runoff and 50% during free capillary suction for the same system. Horizontal or vertical surface cracks of 1 ± 0.5 mm width increased water absorption by 3–5 times during prolonged runoff wetting, comparable to suction at elevated hydrostatic pressure. Furthermore, a trial was done to verify a simplified numerical moisture transport model using the runoff experiment. The results highlighted the necessity for future model refinement and advanced moisture transport modeling in the ACM-system. The developed small-scale setup facilitated easy use and real-time monitoring of moisture conditions during wetting and drying. Future development should include wind-driven rain simulation alongside the existing runoff wetting scenario.

Cultivation and biogeochemical analyses reveal insights into biomineralization caused by piezotolerant iron-reducing bacteria from petroleum reservoirs and their application in MEOR

Interactions between minerals and iron-reducing bacteria under in-situ pressure and temperature conditions play important roles in oil extraction, residual oil methanation, and CO2 storage in petroleum reservoirs. However, the impacts of pressure on dissimilatory iron-reducing bacteria (DIRB) are poorly understood. Herein, the interactions between clay minerals and microbes under elevated hydrostatic pressure conditions were elucidated through enrichment experiments. Bioreduction experiments were performed under hydrostatic pressures of 0.1–40 MPa. Microbial diversity analysis revealed that high pressures significantly increased microbial diversity in petroleum reservoirs, which is helpful for restoring underground ecosystems in situ. The key piezotolerant iron-reducing bacteria in the samples were Shewanella and Flaviflexus. These two genera were isolated for the first time from petroleum reservoirs and identified as piezophiles. The SEM results clearly showed mineral surface dissolution. Moreover, nanoscale secondary minerals were produced during biomineralization. XRD analysis revealed that illite, albite, and clinoptilolite were present after bioreduction. The isolates showed the capacity to inhibit hydro-swelling and prevent plugging-related damage in reservoirs.

Geocatalytically generated methane from low-maturity coal and shale source rocks at low temperatures (80–120 °C) over 52 months

Geocatalytic methanogenesis has been proposed to contribute to methane generation from low-maturity coal and shale source rocks. This study contributes further evidence for geocatalytic methanogenesis from low-maturity source rocks based on long-term experiments lasting up to 52 months. Samples from the Upper Devonian New Albany Shale (Ro 0.54 %) and Springfield Coal No. 2 (Pennsylvanian; Ro 0.54 %) were heated in glass tubes at 80, 100, and 120 °C for 52 months. Sample aliquots from the Upper Cretaceous Second White Specks Formation (Ro 0.42 %) were heated in gold tubes at 80 and 100 °C for 42 months at elevated hydrostatic pressures of 100 to 300 MPa. The product gases — methane (CH4) and carbon dioxide (CO2) — were collected and quantified, and gas yields were corrected for leakage from imperfectly closed pores in samples during heating. The results show that longer heating produced more CH4. The average CH4 yields from New Albany Shale and Springfield Coal No. 2 are 0.47 and 3.0 μmol CH4 per gram of total organic carbon (TOC) over 52 months of heating. Elevated hydrostatic pressure caused lower CH4 yields from the Second White Specks Formation (3.82 to 1.20 μmol g−1 TOC), suggesting that pressure can retard methanogenesis. Maceral type critically controls the methanogenesis potential of low-maturity coal and shale source rocks. Results of this study provide important insights to the origin of natural gas in low-maturity sedimentary basins.

Swimbladder Function in the European Eel Anguilla anguilla

Eels use the swimbladder for buoyancy control. The ductus pneumaticus connecting the esophagus with the swimbladder is closed soon after initial opening of the swimbladder in the glass eel stage, so that eels are functionally physoclist. Subsequent filling of the swimbladder is achieved by activity of gas gland cells in the swimbladder epithelium and countercurrent concentration in the rete mirabile. Gas gland cells produce and release lactic acid and CO2. In blood, acidification induces a release of oxygen from the hemoglobin (Root effect). The resulting increases in PO2 and PCO2 provide diffusion gradients for the diffusion of oxygen and CO2 into the swimbladder, the main gases secreted into the swimbladder. In addition, the partial pressure of these two gases remains elevated in venous blood leaving the swimbladder epithelium and returning to the rete mirabile. Back-diffusion from venous to arterial capillaries in the rete results in countercurrent concentration, allowing for the generation of high gas partial pressures, required for filling the swimbladder under elevated hydrostatic pressure. The transition of the yellow eel to the silver eel stage (silvering) is accompanied by a significant improvement in swimbladder function, but swimbladder volume cannot be kept constant during the daily vertical migrations silver eels perform during their spawning migration back to the spawning grounds in the Sargasso Sea. Infection of the swimbladder with the nematode Anguillicola crassus significantly impairs the function of the swimbladder as a buoyancy organ.

Prospective Randomized Controlled Trial Comparing Laparoscopic Palomo Surgery versus Scrotal Antegrade Sclerotherapy in Adolescent Varicocele.

Varicocele is a common condition in adolescence and the most common correctable cause of infertility. This study aimed to analyze and compare the outcomes of scrotal antegrade sclerotherapy (SAS) and laparoscopic Palomo surgery (LPS) in a tertiary referral centre. Patients with left grade 3 varicocele indicated for surgery were prospectively enrolled and randomly allocated to the SAS and LPS groups, with their respective contralateral normal testes taken as controls. The primary outcome measures were clinical varicocele recurrence, testicular catch-up growth, and post-operative hydrocele. All patients were evaluated clinically and using Doppler ultrasound by radiologists. From 2015 to 2020, 113 patients completed the study and were statistically analyzed (SAS, n = 57; LPS, n = 56). All patients had significantly smaller testes pre-operatively that the testicular volume differences with control testes were -23% in SAS and -19% in LPS. At 12-month follow-up, there were no statistical significant difference in clinical recurrences between the 2 groups (SAS = 5.3% vs LPS = 5.4%, P>.05, non-inferiority test). Testicular catch-up growths were observed in both groups, the mean testicular volume difference between the treatment and control testes reduced from -23% to -8.1% in SAS (P<.001) and -19% to -9.3% in LPS (P<.001) at 12-month follow-up. There was no post-operative hydrocele in SAS compared to 7 in LPS (0% vs 13%, P = .006). Both SAS and LPS are safe and effective procedures for treatment of adolescent varicocele with significant positive effect on testicular catch-up growth. SAS is not inferior to LPS in terms of clinical recurrence rate and with significantly less post-operative hydrocele.

Different behaviour of Müller cells according to their location in the retina: Possible relation with the differential susceptibility of retinal ganglion cells in glaucoma

AbstractPurpose: Glaucoma is a neurodegenerative disease and the leading cause of irreversible blindness in the world. Increased intraocular pressure (IOP) is considered a major risk factor. When visual problems are first detected in patients with glaucoma, half of the retinal ganglion cells (RGCs) have already died, principally in the peripheral retina. Müller glia (MG), which are the main macroglial cells in the retina, play prominent physiological and pathological roles. The change of MG to a reactive phenotype initiates signalling cascades that may serve a neuroprotective role, but may also promote damaging effects on RGCs. Our main hypothesis is that MG exert an important role in RGCs death in glaucoma, being the MG in the periphery the most sensitive to intraocular pressure, promoting the death of RGCs.Methods: Survival of RGCs was analysed by immunocytochemistry in porcine primary co‐cultures of RGCs and MG from central and peripheral retina under control and elevated hydrostatic pressure (EHP) conditions. The conditioned media (CM) from MG primary cultures from central and peripheral retina were collected and analysed by mass spectrometry to identify and quantify proteins in all experimental conditions.Results: We demonstrated that in control condition MG secret neuroprotective factors, and in EHP MG contribute to RGC death. MG from central retina are less sensitive to EHP since RGCs survival further decrease in co‐culture with MG from peripheral retina. Moreover, stretch‐activated nonselective TRPV4 cation channels present in MG are differently activated by the pressure depending of their location within the retina. Proteomic analysis from CM of MG revealed differential protein expression levels, being more pronounced in the CM from MG from peripheral retina under EHP. The proteins identified are mainly associated to apoptosis, oxidative stress, inflammation and angiogenesis.Conclusions: The different sensitivity of the RGCs to IOP in glaucoma could be related with the different activation of neighbouring MG.

Müller‐retinal ganglion cell interactions

AbstractGlaucoma is a neurodegenerative disease and the leading cause of irreversible blindness in the world, whose main risk factor is increased intraocular pressure. When visual problems are first detected in patients with glaucoma, already half of the retinal ganglion cells (RGCs), the neurons that send visual information from the eye to the brain, have died principally in the peripheral retina. The timeframe of cell death is prolonged, lasting even decades after an initial diagnosis. Müller glia (MG) are the main macroglial cell in the retina, play prominent roles regulating normal and pathological physiology and react to neuronal injury in glaucoma. The change to a reactive phenotype of MG initiates signalling cascades that may serve a neuroprotective role but may also proceed to promote damaging effects on RGCs. However, the underlying mechanisms and signalling pathways that specifically promote protective versus destructive roles of reactive glial cells are mostly unclear.Our main hypothesis is that MGs exert an important role in the death of RGCs in glaucoma with the MGs in the periphery being the most sensitive to intraocular pressure, promoting the death of RGCs. Preventing MG response to elevated pressure, MG can neuroprotect RGCs in early stages of glaucoma.We have proved in vitro, that in control condition MG secret neuroprotective factors, and under elevated pressure MG are the responsible for the RGCs death, being less sensitive to the elevated hydrostatic pressure (EHP) the MG present in the central retina. Moreover, stretch‐activated nonselective TRPV4 cation channels present in MG are differently activated by the pressure depending on their location within the retina. Proteomic analysis from the conditioned media (CM) of MG revealed different protein expression levels being more pronounced in the CM from MG from peripheral retina in EHP. Proteins identified correspond mainly to functions such as: apoptosis, oxidative stress, inflammation and angiogenesis.We conclude that the different sensibility of the RGCs to pressure in glaucoma could be related with the different activation of the neighbours MG.Supported by ELKARTEK (KK‐2019/00086), MINECO‐Retos (PID2019‐111139RB‐I00) and PIBA (2020_1_0026).

Implication of Müller glia in glaucoma

AbstractGlaucoma is a neurodegenerative disease and the leading cause of irreversible blindness in the world, whose main risk factor is increased intraocular pressure. When visual problems are first detected in patients with glaucoma, already half of the retinal ganglion cells (RGCs), the neurons that send visual information from the eye to the brain, have died principally in the peripheral retina. The timeframe of cell death is prolonged, lasting even decades after an initial diagnosis. Müller glia (MG) are the main macroglial cell in the retina, play prominent roles regulating normal and pathological physiology and react to neuronal injury in glaucoma. The change to a reactive phenotype of MG initiates signalling cascades that may serve a neuroprotective role, but may also proceed to promote damaging effects on RGCs. However, the underlying mechanisms and signalling pathways that specifically promote protective versus destructive roles of reactive glial cells are mostly unclear.Our main hypothesis is that MGs exert an important role in the death of RGCs in glaucoma with the MGs in the periphery being the most sensitive to intraocular pressure, promoting the death of RGCs. Preventing MG response to elevated pressure, MG can neuroprotect RGCs in early stages of glaucoma.We have proved in vitro, that in control condition MG secret neuroprotective factors, and under elevated pressure MG are the responsible for the RGCs death, being less sensitive to the elevated hydrostatic pressure (EHP) the MG present in the central retina. Moreover, stretch‐activated nonselective TRPV4 cation channels present in MG are differently activated by the pressure depending of their location within the retina. Proteomic analysis from the conditioned media (CM) of MG revealed different protein expression levels being more pronounced in the CM from MG from peripheral retina in EHP. Proteins identified correspond mainly to functions such as: apoptosis, oxidative stress, inflammation and angiogenesis.We conclude that the different sensibility of the RGCs to pressure in glaucoma could be related with the different activation of the neighbours MG.

The Hippo pathway drives the cellular response to hydrostatic pressure

Cells need to rapidly and precisely react to multiple mechanical and chemical stimuli in order to ensure precise context‐dependent responses. This requires dynamic cellular signalling events that ensure homeostasis and plasticity when needed. A less well‐understood process is cellular response to elevated interstitial fluid pressure, where the cell senses and responds to changes in extracellular hydrostatic pressure. Here, using quantitative label‐free digital holographic imaging, combined with genome editing, biochemical assays and confocal imaging, we analyse the temporal cellular response to hydrostatic pressure. Upon elevated cyclic hydrostatic pressure, the cell responds by rapid, dramatic and reversible changes in cellular volume. We show that YAP and TAZ, the co‐transcriptional regulators of the Hippo signalling pathway, control cell volume and that cells without YAP and TAZ have lower plasma membrane tension. We present direct evidence that YAP/TAZ drive the cellular response to hydrostatic pressure, a process that is at least partly mediated via clathrin‐dependent endocytosis. Additionally, upon elevated oscillating hydrostatic pressure, YAP/TAZ are activated and induce TEAD‐mediated transcription and expression of cellular components involved in dynamic regulation of cell volume and extracellular matrix. This cellular response confers a feedback loop that allows the cell to robustly respond to changes in interstitial fluid pressure.

Photocatalysis/enzymolysis-based biomimetic Schottky junction reduces tumor interstitial solid and fluid phases for deep-penetrating tumor therapy

Tumor interstitial solid phase-induced physical obstacles and fluid phase-induced hydrostatic pressure are regarded as the two main intractable barriers of drug delivery, leading to the survive of deep-seated tumor stem cells. Herein, a rational strategy is presented based on near-infrared light-stimuli enzymolysis and photocatalysis to decompose the tumor interstitial solid and fluid phases for boosting the tumor penetration of nanomedicine. In detail, a cuprous oxide/sliver nano-photocatalyst (Cu2O/Ag) is designed, which is covered with the thermosensitive papain-loaded tumor-homing homologous cytomembrane to form the nanomedicine (Cu2O/Ag-P@M). With the light irradiation, the heat generated by Cu2O/Ag promote the enzymolysis of extracellular matrix by papain, which eliminate the physical obstacles. Moreover, the photocatalytic water splitting of Cu2O/Ag reduce the volume of tumor interstitial fluid, which decrease the elevated hydrostatic pressure to boost the tumor penetration of nanomedicine. Additionally, during the intratumoral delivery, Cu2O/Ag-P@M is able to realize anti-tumor photothermal therapy and chemotherapy. The results indicate that the Cu2O/Ag-P@M decompose a majority of tumor extracellular matrix and interstitial fluid under light irradiation. The tumor interstitial hydrostatic pressure is reduced by 69.7%. The tumor penetration of Cu2O/Ag-P@M + L treated group is 5.03-fold than the Cu2O/Ag@M−L group, leading to the 95.19% of tumor inhibition rate.