Non-invasive determination of critical dissolved oxygen thresholds for stress physiology in fish using triple-oxygen stable isotopes and aquatic respirometry.

Understanding the critical thresholds of dissolved oxygen (O2) that trigger adaptive physiological responses in aquatic organisms is long hampered by a lack of robust, non-lethal or non-invasive methodologies. The isotope fractionation of triple O2 isotopes (18O/17O/16O) during respiration is linked to the amount of oxygen utilised, offering a potential avenue for new insights. Our experimental research involved measuring the oxygen isotope fractionation of dissolved O2 in closed-system aquatic respirometry experiments with wild sticklebacks (Gasterosteus aculeatus). These fish were either naturally adapted or experimentally acclimated to hypoxic and normoxic conditions. The aim was to observe their oxygen usage and isotope fractionation in response to increasingly severe hypoxia. Initial observations revealed a progressive 18O enrichment from the preferential uptake of 16O to a dissolved oxygen threshold of 3-5 mg O2 L-1, followed by an apparent reversal in oxygen isotope fractionation, which is mixing of 16O and 17O with the remaining O2 pool across all populations and indicative of a systematic change in oxygen metabolism among the fish. Unexpectedly, sticklebacks adapted to hypoxia but acclimated to normoxia exhibited stronger oxygen isotope fractionation compared to those adapted to normoxia and acclimated to hypoxia, contradicting the hypothesis that hypoxia adaptation would lead to reduced isotope discrimination due to more efficient oxygen uptake. These preliminary experimental results highlight the novel potential of using dissolved O2 isotopes as a non-invasive, non-lethal method to quantitatively assess metabolic thresholds in aquatic organisms. This approach could significantly improve our understanding of the critical oxygen responses and adaptation mechanisms in fish and other aquatic organisms across different oxygen environments, marking a significant step forward in aquatic ecological and physiological research.

Aquatic processing enhances the loss of aged carbon from drained and burned peatlands.

Water-logged peatlands store tremendous amounts of soil carbon (C) globally, accumulating C over millennia. As peatlands become disturbed by human activity, these long-term C stores are getting destabilized and ultimately released as greenhouse gases that may exacerbate climate change. Oxidation of the dissolved organic carbon (DOC) mobilized from disturbed soils to streams and canals may be one avenue for the transfer of previously stored, millennia-aged C to the atmosphere. However, it remains unknown whether aged peat-derived DOC undergoes oxidation to carbon dioxide (CO2) following disturbance. Here, we use a new approach to measure the radiocarbon content of CO2 produced from the oxidation of DOC in canals overlying peatland soils that have undergone widespread disturbance in Indonesia. This work shows for the first time that aged DOC mobilized from drained and burned peatland soils is susceptible to oxidation by both microbial respiration and photomineralization over aquatic travel times for DOC. The bulk radiocarbon age of CO2 produced during canal oxidation ranged from modern to ~1300 years before present. These ages for CO2 were most strongly influenced by canal water depth, which was proportional to the water table level where DOC is mobilized from disturbed soils to canals. Canal microbes preferentially respired older or younger organic C pools to CO2, and this may have been facilitated by the use of a small particulate organic C pool over the dissolved pool. Given that high densities of canals are generally associated with lower water tables and higher fire risk, our findings suggest that peatland areas with high canal density may be a hotspot for the loss of aged C on the landscape. Taken together, the results of this study show how and why aquatic processing of organic C on the landscape can enhance the transfer of long-term peat C stores to the atmosphere following disturbance.

Conditional essentiality of the 11-subunit complex I-like enzyme in strict anaerobes: the case of Desulfitobacterium hafniense strain DCB-2.

In oxidative phosphorylation, respiratory complex I serves as an entry point in the electron transport chain for electrons generated in catabolic processes in the form of NADH. An ancestral version of the complex, lacking the NADH-oxidising module, is encoded in a significant number of bacterial genomes. Amongst them is Desulfitobacterium hafniense, a strict anaerobe capable of conserving energy via organohalide respiration. This study investigates the role of the complex I-like enzyme in D. hafniense energy metabolism using rotenone as a specific complex I inhibitor under different growth conditions. The investigation revealed that the complex I-like enzyme was essential for growth with lactate and pyruvate but not in conditions involving H2 as an electron donor. In addition, a previously published proteomic dataset of strain DCB-2 was analysed to reveal the predominance of the complex under different growth conditions and to identify potential redox partners. This approach revealed seven candidates with expression patterns similar to Nuo homologues, suggesting the use of diverse electron sources. Based on these results, we propose a model where the complex I-like enzyme serves as an electron entry point into the respiratory chain for substrates delivering electrons within the cytoplasm, such as lactate or pyruvate, with ferredoxins shuttling electrons to the complex.

Increased extinction probability and altered physiological characteristics in pirimicarb-tolerant Daphnia magna.

We evaluated the physiological characteristics of chemical-tolerant cladocerans. Over the course of 26 generations (F25), Daphnia magna was continuously exposed to pirimicarb (carbamate) solutions (0, 3.8, 7.5, and 15 µg/L) in sub-lethal or lethal levels. The 48 h EC50 values (29.2-29.9 µg/L) for 7.5 and 15 µg/L exposure groups were found to be nearly two times higher than that in the control (17.2 µg/L). Subsequently, we investigated whether the extinction probability changed when the chemical-tolerant daphnids were fed two different types of food, Chlorella vulgaris and Synechococcus leopoliensis. Furthermore, we ascertained how chemical tolerance influences respiration and depuration rates. The 48 h EC50 value was positively related to the extinction probability when the daphnids were fed S. leopoliensis. Because the measured lipid content of S. leopoliensis was three times lower than that of C. vulgaris, the tolerant daphnids struggled under nutrient-poor conditions. Respiration rates across all pirimicarb treatment groups were higher than those in the control group, suggesting that they may produce large amounts of energy through respiration to maintain the chemical tolerance. Since the pirimicarb depuration rate for 7.5 µg/L exposure groups was higher than that in the control, the altered metabolic/excretion rate may be one factor for acquiring chemical tolerance. These altered physiological characteristics are crucial parameters for evaluating the mechanisms of chemical tolerance and associated fitness costs.

The effect of acute respiratory demand on postural control: A systematic review.

BACKGROUND: Postural control can be challenged by breathing. RESEARCH QUESTION: What is the effect of an acute increase in respiratory demand on postural control compared to quiet breathing? METHODS: A systematic review was conducted. Electronic databases were systematically searched until October 18, 2022 on studies reporting changes in center of pressure (CoP) motion related to an acute manipulation of respiratory demand compared to quiet breathing during upright standing in healthy participants and/or participants with a clinical condition. RESULTS: Twenty-one studies in healthy participants showed that voluntary (not metabolic-induced) hyperventilation or inspiratory resistive loading significantly increased CoP motion, while breath-holding decreased CoP motion, compared to quiet breathing (p< 0.05). Manipulating respiratory rate or breathing patterns did not reveal consistent results. Four studies showed that people with low back pain showed similar CoP responses to increasing respiratory demand (p> 0.05), except for breathing at different rates, whereas they showed greater CoP motion during quiet breathing. SIGNIFICANCE: The extent of postural disturbance depended on the breathing mode and how it was quantified (i.e., CoP coupled with breathing movement or overall CoP measures). Voluntary hyperventilation and inspiratory resistive loading increased postural sway. For voluntary hyperventilation, this could be explained by CoP motion being directly coupled to chest wall movements whereas metabolic-induced hyperventilation did not increase CoP motion or CoP coupling with breathing. Breath-holding decreased postural sway. Patients with low back pain show greater postural sways than pain-free individuals during quiet breathing, although they exhibit similar postural adaptations to respiratory-related challenges as controls.

High PEEP/low FiO2 ventilation is associated with lower mortality in COVID-19.

RATIONALE: The positive end-expiratory pressure (PEEP) strategy in patients with coronavirus 2019 (COVID-19) acute respiratory distress syndrome (ARDS) remains debated. Most studies originate from the initial waves of the pandemic. Here we aimed to assess the impact of high PEEP/low FiO2 ventilation on outcomes during the second wave in the Netherlands. METHODS: Retrospective observational study of invasively ventilated COVID-19 patients during the second wave. Patients were categorized based on whether they received high PEEP or low PEEP ventilation according to the ARDS Network tables. The primary outcome was ICU mortality, and secondary outcomes included hospital and 90-day mortality, duration of ventilation and length of stay, and the occurrence of kidney injury. Propensity matching was performed to correct for factors with a known relationship to ICU mortality. RESULTS: This analysis included 790 COVID-ARDS patients. At ICU discharge, 32 (22.5%) out of 142 high PEEP patients and 254 (39.2%) out of 848 low PEEP patients had died (HR 0.66 [0.46-0.96]; P = 0.03). High PEEP was linked to improved secondary outcomes. Matched analysis did not change findings. CONCLUSIONS: High PEEP ventilation was associated with improved ICU survival in patients with COVID-ARDS.

Effect of esketamine combined with dexmedetomidine on delirium in sedation for mechanically ventilated ICU patients: protocol for a nested substudy within a randomized controlled trial.

BACKGROUND: Use of sedatives and analgesics is associated with the occurrence of delirium in critically ill patients receiving mechanical ventilation. Dexmedetomidine reduces the occurrence of delirium but may cause hypotension, bradycardia, and insufficient sedation. This substudy aims to determine whether the combination of esketamine with dexmedetomidine can reduce the side effects and risk of delirium than dexmedetomidine alone in mechanically ventilated patients. METHODS: This single-center, randomized, active-controlled, superiority trial will be conducted at The First Affiliated Hospital of Nanjing Medical University. A total of 134 mechanically ventilated patients will be recruited and randomized to receive either dexmedetomidine alone or esketamine combined with dexmedetomidine, until extubation or for a maximum of 14 days. The primary outcome is the occurrence of delirium, while the second outcomes include the number of delirium-free days; subtype, severity, and duration of delirium; time to first onset of delirium; total dose of vasopressors and antipsychotics; duration of mechanical ventilation; ICU and hospital length of stay (LOS); accidental extubation, re-intubation, re-admission; and mortality in the ICU at 14 and 28 days. DISCUSSION: There is an urgent need for a new combination regimen of dexmedetomidine due to its evident side effects. The combination of esketamine and dexmedetomidine has been applied throughout the perioperative period. However, there is still a lack of evidence on the effects of this regimen on delirium in mechanically ventilated ICU patients. This substudy will evaluate the effects of the combination of esketamine and dexmedetomidine in reducing the risk of delirium for mechanically ventilated patients in ICU, thus providing evidence of this combination to improve the short-term prognosis. The study protocol has obtained approval from the Medical Ethics Committee (ID: 2022-SR-450). TRIAL REGISTRATION: ClinicalTrials.gov: NCT05466708, registered on 20 July 2022.

FERMT1 suppression induces anti-tumor effects and reduces stemness in glioma cancer cells.

OBJECTIVE: Glioma is a leading cause of mortality worldwide, its recurrence poses a major challenge in achieving effective treatment outcomes. Cancer stem cells (CSCs) have emerged as key contributors to tumor relapse and chemotherapy resistance, making them attractive targets for glioma cancer therapy. This study investigated the potential of FERMT1 as a prognostic biomarker and its role in regulating stemness through cell cycle in glioma. METHODS: Using data from TCGA-GBM, GSE4290, GSE50161 and GSE147352 for analysis of FERMT1 expression in glioma tissues. Then, the effects of FERMT1 knockdown on cell cycle, proliferation, sphere formation ability, invasion and migration were investigated. The influences of FERMT1 on expression of glycolysis-related proteins and levels of ATP, glucose, lactate and G6PDH were also explored. Furthermore, the effects of FERMT1 knockdown on cellular metabolism were evidenced. RESULTS: Significant upregulation of FERMT1 in glioma tissues was observed. Silencing FERMT1 not only affected the cell cycle but also led to a notable reduction in proliferation, invasion and migration. The expression of glycolysis-associated proteins including GLUT1, GLUT3, GLUT4, and SCO2 were reduced by FERMT1 knockdown, resulted in increased ATP and glucose as well as decreased lactic acid and G6PDH levels. FERMT1 knockdown also inhibited cellular metabolism. Moreover, FERMT1 knockdown significantly reduced sphere diameter, along with inhibiting the expression of transcription factors associated with stemness in glioma cells. CONCLUSION: These findings demonstrated that FERMT1 could be an ideal target for the advancement of innovative strategies against glioma treatment via modulating cellular process involved in stemness regulation and metabolism.

An efficient and high-throughput method for the evaluation of mitochondrial dysfunction in frozen brain samples after traumatic brain injury.

Mitochondrial function analysis is a well-established method used in preclinical and clinical investigations to assess pathophysiological changes in various disease states, including traumatic brain injury (TBI). Although there are multiple approaches to assess mitochondrial function, one common method involves respirometric assays utilizing either Clark-type oxygen electrodes or fluorescent-based Seahorse analysis (Agilent). However, these functional analysis methods are typically limited to the availability of freshly isolated tissue samples due to the compromise of the electron transport chain (ETC) upon storage, caused by freeze-thaw-mediated breakdown of mitochondrial membranes. In this study, we propose and refine a method for evaluating electron flux through the ETC, encompassing complexes I, II, and IV, in frozen homogenates or mitochondrial samples within a single well of a Seahorse plate. Initially, we demonstrate the impact of TBI on freshly isolated mitochondria using the conventional oxidative phosphorylation protocol (OxPP), followed by a comparison with ETC analysis conducted on frozen tissue samples within the context of a controlled cortical impact (CCI) model of TBI. Additionally, we explore the effects of mitochondrial isolation from fresh versus snap-frozen brain tissues and their storage at -80°C, assessing its impact on electron transport chain protocol (ETCP) activity. Our findings indicate that while both sets of samples were frozen at a single time point, mitochondria from snap-frozen tissues exhibited reduced injury effects compared to preparations from fresh tissues, which were either homogenized or isolated into mitochondria and subsequently frozen for later use. Thus, we demonstrate that the preparation of homogenates or isolated mitochondria can serve as an appropriate method for storing brain samples, allowing for later analysis of mitochondrial function, following TBI using ETCP.

Lignite reduces carbon and nitrogen loss from litter in commercial broiler housing.

The loss of carbon and nitrogen from broiler litter limits nutrient recycling and is damaging to the environment. This study investigated lignite, a low-rank brown coal, as an amendment to reduce the loss of carbon and nitrogen from broiler litter over 3 consecutive grow-out cycles, November 2021 to May 2022, at a commercially operated farm in Victoria, Australia. Lignite-treated litter contained significantly more carbon and nitrogen, with an increase of 70.1 g/bird and 12.6 g/bird for carbon and nitrogen, respectively. Lignite also reduced aerobic microbial respiration, with a 46.0% reduction in CO2 flux recorded in week 7 of the study, resulting in reduced mass loss. It is expected that this is a key mechanism responsible for nutrient retention in litter following treatment with lignite. Furthermore, lignite treatment lowered litter moisture content by 7, 6 and 3 percentage points for grow-out 1, 2 and 3, respectively. These findings present lignite as a beneficial litter amendment for increasing the nutrient value of waste and reducing carbon dioxide emissions. The study highlights the potential of lignite to reduce the environmental impact of poultry production and presents an alternative use for lignite as an existing resource.

Altered ventilatory responses to hypercapnia-hypoxia challenges in a preclinical SUDEP model involve orexin neurons.

Failure to recover from repeated hypercapnia and hypoxemia (HH) challenges caused by severe GCS and postictal apneas may contribute to sudden unexpected death in epilepsy (SUDEP). Our previous studies found orexinergic dysfunction contributes to respiratory abnormalities in a preclinical model of SUDEP, Kcna1-/- mice. Here, we developed two gas challenges consisting of repeated HH exposures and used whole body plethysmography to determine whether Kcna1-/- mice have detrimental ventilatory responses. Kcna1-/- mice exhibited an elevated ventilatory response to a mild repeated hypercapnia-hypoxia (HH) challenge compared to WT. Moreover, 71% of Kcna1-/- mice failed to survive a severe repeated HH challenge, whereas all WT mice recovered. We next determined whether orexin was involved in these differences. Pretreating Kcna1-/- mice with a dual orexin receptor antagonist rescued the ventilatory response during the mild challenge and all subjects survived the severe challenge. In ex vivo extracellular recordings in the lateral hypothalamus of coronal brain slices, we found reducing pH either inhibits or stimulates putative orexin neurons similar to other chemosensitive neurons; however, a significantly greater percentage of putative orexin neurons from Kcna1-/-mice were stimulated and the magnitude of stimulation was increased resulting in augmentation of the calculated chemosensitivity index relative to WT. Collectively, our data suggest that increased chemosensitive activity of orexin neurons may be pathologic in the Kcna1-/- mouse model of SUDEP, and contribute to elevated ventilatory responses. Our preclinical data suggest that those at high risk for SUDEP may be more sensitive to HH challenges, whether induced by seizures or other means; and the depth and length of the HH exposure could dictate the probability of survival.

The Na+-translocating NADH:quinone oxidoreductase (Na+-NQR): Physiological role, structure and function of a redox-driven, molecular machine.

Many bacterial processes are powered by the sodium motive force (smf) and in case of pathogens, the smf contributes to virulence. Vibrio cholerae, the causative agent of Cholera disease, possesses a Na+-translocating NADH:quinone oxidoreductase (NQR), a six-subunit membrane protein assembly. The 3D structure of NQR revealed the arrangement of the six subunits NqrABCDEF, the position of all redox cofactors (four flavins, two [2Fe-2S] centers) and the binding sites for the substrates NADH (in NqrF) and ubiquinone (in NqrB). Upon oxidation of NADH, electrons are shuttled twice across the membrane, starting with cytoplasmic FADNqrF and electron transfer to the [2Fe2S] clusterNqrF and from there to an intra-membranous [2Fe-2S] clusterNqrDE, periplasmic FMNNqrC, FMNNqrB and from there to riboflavinNqrB. This riboflavin is located at the cytoplasmic entry site of the sodium channel in NqrB, and it donates electrons to ubiquinone-8 positioned at the cytoplasmic side of NqrB. Targeting the substrate binding sites of NQR is a promising strategy to identify new inhibitors against many bacterial pathogens. Detailed structural information on the binding mode of natural inhibitors and small molecules in the active sites of NQR is now available, paving the way for the development of new antibiotics. The NQR shows different conformations as revealed in recent cryo-EM and crystallographic studies combined with spectroscopic analyses. These conformations represent distinct steps in the catalytic cycle. Considering the structural and functional data available, we propose a mechanism of Na+-NQR based on conformational coupling of electron transfer and Na+ translocation reaction steps.

METTL3-mediated NDUFB5 m6A modification promotes cell migration and mitochondrial respiration to promote the wound healing of diabetic foot ulcer.

BACKGROUND: Diabetic foot ulcer (DFU) is the most devastating complication of diabetes mellitus (DM) and plays a major role in disability and death in DM patients. NADH: ubiquinone oxidoreductase subunit B5 (NDUFB5) plays an important role in maintaining mitochondrial respiration, but whether it is involved in regulating the progression of advanced glycation end products (AGEs)-mediated DFU is still unclear. METHODS: Firstly, the role of AGEs on cell viability, migration, and mitochondrial respiration in human umbilical vein endothelial cells (HUVECs) was explored in vitro. Next, NDUFB5 expression was detected in human samples and AGEs-treated HUVECs, and NDUFB5's effect on AGEs-induced HUVECs injury and skin wound in diabetic mice was further clarified. In addition, the role of m6A modification mediated by methyltransferase-like 3 (METTL3) in regulating NDUFB5 expression and AGEs-induced HUVECs injury was investigated. RESULTS: NDUFB5 promoted cell viability, migration, and mitochondrial respiration in AGEs-treated HUVECs, whereas mitochondrial fusion promoter M1 facilitated cell viability, migration, and mitochondrial oxiadative respiration in NDUFB5 knockdown HUVECs. Meanwhile, NDUFB5 promotes skin wound healing in diabetic mice. Besides, METTL3-mediated m6A modification and insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) enhanced NDUFB5 expression in HUVECs. Furthermore, METTL3 promoted cell viability, migration, and mitochondrial respiration in AGEs-treated HUVECs by increasing NDUFB5. CONCLUSION: METTL3-mediated NDUFB5 m6A modification inhibits AGEs-induced cell injury in HUVECs. METTL3 and NDUFB5 might serve as potential targets for DFU therapy in the future.

Diaphragm dysfunction is found in patients with chronic painful temporomandibular disorder: A case-control study.

Aim: To determine whether patients with chronic painful temporomandibular disorder (TMD) had abnormal diaphragm function compared to healthy controls and to explore the correlation between diaphragm contractility, psychological status, and pain characteristics. Methods: A single-blinded, case-control study was conducted involving 23 chronic painful TMD patients and 22 healthy volunteers. The examination and diagnosis were performed according to the Diagnostic Criteria for Temporomandibular Disorders, and questionnaires were used to evaluate pain, depression, anxiety, and physical symptoms status. B-mode ultrasound was used to measure diaphragm thickness and contractility. The sonographer responsible for measuring the diaphragm was blinded to group membership. Results: 1. Depression, anxiety, and physical symptoms scores were significantly higher in the patients than in the controls (p < 0.05). 2. The Interference Score of pain was significantly correlated with depression and physical symptoms (p < 0.01). 3. Bilateral diaphragm contractility was significantly smaller in the patients than in the controls (right: P = 0.003; left: P = 0.001). 3. There was no correlation between diaphragm contractility on the left and right sides in the patients (r = -0.112, P = 0.611), while there was a positive correlation in the control group (r = 0.638, P = 0.001). 4. No correlation was found between the degree of diaphragm contractility, psychological status, and pain scores. Conclusions: 1. Patients with chronic painful TMD have worse psychological status, including depression, anxiety, and physical symptoms. 2. Patients with chronic painful TMD have a smaller degree of bilateral diaphragm contractility and more significant left-right incongruity, which indicated that diaphragm dysfunction may be correlated with chronic painful temporomandibular disorder.

Stimulation of the Internal Superior Laryngeal Nerve as a Potential Therapy for Obstructive Sleep Apnea in a Porcine Model.

Impaired pharyngeal sensing of negative pressure can lead to a blunted response of the upper airway dilator muscles and contribute to the development of obstructive sleep apnea (OSA). This response is modulated by the nerve fibers in the internal branch of the superior laryngeal nerve (iSLN), mediating negative pressure sensation. Artificial excitation of these fibers could be a potential treatment target for OSA. To evaluate this, electrostimulation of the iSLN was performed in a porcine isolated upper airway model. Artificial obstructions were induced by varying levels of negative pressure and the ability of the animal to resolve these obstructions was evaluated. The pressure at which the animal was still able to resolve the obstruction was quantified as 'Resolvable Pressure'. Thereby, the effects on pharyngeal patency (n=35) and the duration of the therapeutic effect outlasting the stimulation (n=6) were quantified. Electrostimulation prior to the introduction of an artificial obstruction improved the median resolvable pressure from -28.3 cmH2O [IQR: -45.9; -26.1] to -92.6 cmH2O [IQR: -105.1; -78.6]. The median therapeutic effect was found to outlast the last stimulation burst applied by 163 s when five stimulation bursts were applied in short succession [IQR: 58; 231], 58 s when two were applied [IQR: 7; 65], and 6 s when one was applied [IQR: 0; 51]. Stimulation of the iSLN increased EMG in the genioglossus. The proposed treatment concept can improve pharyngeal patency in the model. Transfer of the results to clinical application could enable the development of a new neuromodulation therapy for OSA.

The exposure to extremely low frequency electromagnetic-fields inhibits the growth and potentiates the sensitivity to chemotherapy of bidimensional and tridimensional human osteosarcoma models.

We previously established a thermodynamical model to calculate the specific frequencies of extremely low frequency-electromagnetic field (ELF-EMF) able to arrest the growth of cancer cells. In the present study, for the first time, we investigated the efficacy of this technology on osteosarcoma, and we applied a precise frequency of the electromagnetic field on three human osteosarcoma cell lines, grown as adherent cells and spheroids. We evaluated the antitumour efficacy of irradiation in terms of response to chemotherapeutic treatments, which is usually poor in this type of cancer. Importantly, the results of this novel combinatorial approach revealed that the specific exposure can potentiate the efficacy of several chemotherapeutic drugs, both on bidimensional and tridimensional cancer models. The effectiveness of cisplatinum, methotrexate, ifosfamide and doxorubicin was greatly increased by the concomitant application of the specific ELF-EMF. Moreover, our experiments confirmed that ELF-EMF inhibited the proliferation and modulated the mitochondrial metabolism of all cancer models tested, whereas mesenchymal cells were not affected. The latter finding is extremely valuable, given the importance of preserving the cell reservoir necessary for tissue regeneration after chemotherapy. Altogether, this novel evidence opens new avenues to the clinical applications of ELF-EMF in oncology.

Regulating Water Adsorption Sites of Keto-Enamine COF by Base Exfoliation and Deprotonation for Enhanced Humidity Response.

Covalent organic framework (COF) has received much attention owing to its unique framework structure formed by diverse organic units. However, challenges, including low conductivity, structure instability, and limited control of adsorption and desorption processes, stimulate the modification of COF in electronic sensors. Herein, inspired by the alterable structure of COF in different solvents, a facile base exfoliation and deprotonation method is proposed to regulate the water adsorption sites and improve the intrinsic conductivity of TpPa-1 COF. TpPa-1 COF powders are exfoliated to nanosheets to increase water adsorption, while the deprotonation is utilized to adjust the affinity of water molecules on TpPa-1 COF framework, contributing to water accumulation in the 1D pores. The as-fabricated TpPa-1 COF sensor exhibits a decreased recovery time from 419 to 49 s, forming a linear relation between relative humidity (RH) value and humidity response. The excellent chemical stability of the covalent bond of TpPa-1 COF contributes to the excellent stable device performance in 30 days, promoting further integration and data analysis in respiration monitoring.

Mitochondrial functions and fatty acid profiles in fish heart: an insight into physiological limitations linked with thermal tolerance and age.

Heart failure is among the first major consequences of heat stress in aquatic ectotherms. Mitochondria produce most of the ATP used by the heart and represent almost half of the volume in cardiac cells. It has therefore been hypothesized that mitochondrial dysfunctions may be highly involved in heart failure associated with heat stress. The present study aims to investigate if CTmax is linked to the thermal sensitivity of three-spined sticklebacks' (G. aculeatus) cardiac mitochondria, and if it is influenced by heart fatty acid composition and age. To do so, we measured the CTmax of 30 fish. The cardiac mitochondrial oxygen consumption was measured by high resolution respirometry at three temperatures and heart lipid profiles were obtained by Gas chromatography (GC) coupled with a Flame Ionization Detector (FID). Fish age was estimated via otolith readings. Fatty acid profiles showed no correlation with CTmax, but EPA levels were higher in older individuals. Mitochondrial respiration was measured in 35 fish using high resolution respirometry. It was strongly affected by temperature and showed a drastic drop in OXPHOS respiration fed by Complex I and Complex I+II, while uncoupled respiration plateaued at CTmax temperature. Our results suggest that Complex I is an important modulator of the impact of temperature on mitochondrial respiration at high temperatures but is not the main limiting factor in physiological conditions (maximal OXPHOS). Mitochondrial respiration was also affected by fish age, showing a general decrease in older individuals.

Workload and spirometry associated with untethered swimming in horses.

BACKGROUND: Swimming has been used empirically for rehabilitation and conditioning of horses. However, due to challenges imposed by recording physiological parameters in water, the intensity of free swimming effort is unknown. OBJECTIVES: Measure the physiological workload associated with untethered swimming in horses. Five fit Arabian endurance horses were assessed while swimming in a 100 m-long indoor pool. Horses were equipped with a modified ergospirometry facemask to measure oxygen consumption (V̇O2) and ventilatory parameters (inspired/expired volumes, VI, VE; peak inspiratory/expiratory flows, PkVI, PkVE; respiratory frequency, Rf; minute ventilation, VE; inspiratory/expiratory durations and ratios, tI, tE, tI/ttot, tE/ttot); and an underwater electrocardiogram that recorded heart rate (HR). Postexercise venous blood lactate and ammonia concentrations were measured. Data are reported as median (interquartile ranges). RESULTS: Horses showed bradypnea (12 breaths/min (10-16)) for the first 30 s of swimming. V̇O2 during swimming was 43.2 ml/(kg.min) (36.0-56.6). Ventilatory parameters were: VI = 16.7 L (15.3-21.8), VE = 14.7 L (12.4-18.9), PkVI = 47.8 L/s (45.8-56.5), PkVE = 55.8 L/s (38.3-72.5), Rf = 31.4 breaths/min (20.0-33.8), VE = 522.9 L/min (414.7-580.0), tI = 0.5 s (0.5-0.6), tE = 1.2 s (1.1-1.6), tI/ttot = 0.3 (0.2-0.4), tE/ttot = 0.7 (0.6-0.8). Expiratory flow tracings showed marked oscillations that coincided with a vibrating expiratory sound. HR was 178.0 bpm (148.5-182.0), lactate = 1.5 mmol/L (1.0-1.9) and ammonia = 41.0 µmol/L (36.5-43.5). CONCLUSIONS: Free (untethered) swimming represents a submaximal, primarily aerobic exercise in horses. The breathing pattern during swimming is unique, with a relatively longer apneic period at the beginning of the exercise and an inspiratory time less than half that of expiration.

Impact of the SIK3 Pathway Inhibition on Osteoclast Differentiation via Oxidative Phosphorylation.

Maintenance of bone homeostasis and the balance between bone resorption and formation are crucial for maintaining skeletal integrity. This study sought to investigate the role of salt-inducible kinase 3 (SIK3), a key regulator in cellular energy metabolism, during the differentiation of osteoclasts. Despite osteoclasts being high energy-consuming cells essential for breaking down mineralized bone tissue, the specific function of SIK3 in this process remains unclear. To address this issue, we generated osteoclast-specific SIK3 conditional knockout mice and assessed the impact of SIK3 deletion on bone homeostasis. Our findings revealed that SIK3 conditional knockout mice exhibited increased bone mass and an osteopetrosis phenotype, suggesting a pivotal role for SIK3 in bone resorption. Moreover, we assessed the impact of pterosin B, a SIK3 inhibitor, on osteoclast differentiation. The treatment with pterosin B inhibited osteoclast differentiation, reduced the numbers of multinucleated osteoclasts, and suppressed resorption activity in vitro. Gene expression analysis demonstrated that SIK3 deletion and pterosin B treatment influence a common set of genes involved in osteoclast differentiation and bone resorption. Furthermore, pterosin B treatment altered intracellular metabolism, particularly affecting key metabolic pathways, such as the tricarboxylic acid cycle and oxidative phosphorylation. These results provide valuable insights into the involvement of SIK3 in osteoclast differentiation and the molecular mechanisms underlying osteoclast function and bone diseases.

Osteoporosis is a disease that causes bones to become weak and fragile, increasing the risk of fractures especially in elderly. It is caused by an imbalance between the formation of new bone and the destruction of old bone. Cells called osteoclasts are responsible for breaking down old bone. Excessive osteoclast activity results in bone loss and osteoporosis. Our research has identified a LKB1-SIK3 pathway, which acts as an energy sensor in osteoclasts. We found that this pathway is activated when osteoclast activity is increased, and we were able to reduce osteoclast activity by genetically removing or inhibiting SIK3. These findings suggest that targeting the LKB1-SIK3 pathway may be a promising new approach for the treatment of osteoporosis. Developing drugs that inhibit SIK3 may slow bone loss and reduce the risk of fractures in osteoporotic patients.