Oxygen-dependent Processes Research Articles

Necroptosis as a consequence of photodynamic therapy in tumor cells.

Photodynamic therapy (PDT) is an alternative to cancer treatment, demonstrating selectivity and significant cytotoxicity on malignant tissues. Such therapy involves two nontoxic components: photosensitizer (PS) and non-ionizing radiation. In optimal dosage combinations, PDT causes cellular and tissue effects by oxygen-dependent processes, leading tumor cells to regulated cell death pathways. Regulated necrosis, called necroptosis, can be triggered by PDT and is characterized by caspase-8 inhibition and RIPK1, RIPK3, and MLKL activities, leading to plasma membrane pores formation with subsequent cellular content release into the extracellular space. For this review, studies accessed by PubMed describing the relation between necroptosis and PDT were summarized. The results showed that PDT can trigger necroptosis mechanisms in different tumor cells. Moreover, a mix of different cell death types can co-occur. It is also important to highlight that necroptosis triggered by PDT is related to damage-associated molecular patterns (DAMPs) release, involving immunogenic cell death and vaccination. The cell death response is directly related to the photosensitizer chemical characteristics, concentration, incubation time, cellular location, and irradiation parameters. The synergism among all cell death types is an excellent advantage for avowing tumor resistance mechanisms and developing new solutions.

Abstract C038: Cancer-associated fibroblasts maintain critical pancreatic cancer cell lipid homeostasis in the tumor microenvironment

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy whose abundant cancer-associated fibroblasts (CAFs) create a hallmark “desmoplasia” that severely limits oxygen and nutrient delivery. Hypoxia inhibits oxygen-dependent metabolic processes. For example, unsaturated lipid biosynthesis relies on oxygen to maintain desaturase enzymatic activities. Here, we investigated the mechanisms by which PDAC cells maintain lipid homeostasis under these conditions. Exogenous unsaturated lipids, rather than de novo synthesis, sustain PDAC cell viability by relieving endoplasmic reticulum (ER) stress under nutrient scarcity. Furthermore, CAFs are less hypoxic than adjacent malignant cells in vivo due to proximal blood vessel accessibility, nominating them as a potential source of these obligatory species. CAF-conditioned medium promoted PDAC cell survival upon nutrient and oxygen deprivation, an effect reversed by delipidation. We determined that lysophosphatidylcholines (LPCs) are particularly enriched in CAF-conditioned medium and preferentially taken up by PDAC cells, where they are converted to phosphatidylcholines (PCs) to sustain membrane integrity. Inhibiting LPC to PC conversion reversed the ability of exogenous unsaturated LPCs to sustain cancer cell survival and restrain ER stress in vitro and in vivo. Collectively, these results reveal a critical lipid cross-feeding mechanism enabling PDAC cell survival and identify an innovative approach to targeting this metabolic dependency. Efforts to target lipid crosstalk between CAFs and PDAC cells will be discussed. Citation Format: Xu Han, Michelle Burrows, Laura C Kim, Jimmy Xu, Will Vostrejs, Tran Ngoc Van Le, Yanqing Jiang, Edna Cukierman, Reiss Binder Kim, Ben Z Stanger, Clementina Mesaros, Brian Keith, Celeste Simon. Cancer-associated fibroblasts maintain critical pancreatic cancer cell lipid homeostasis in the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C038.

Elucidation of the Role of L-Arginine and Nω-Nitro-L-Arginine in the Treatment of Rats with Different Levels of Hypoxic Tolerance and Exposure to Lead Nitrate

Background/Aims: Individual resistance to hypoxia is an important feature of the physiological profile of an organism, particularly in relation to lead-induced toxicity. Methods: Our study focused on evaluating parameters of mitochondrial oxygen consumption, microsomal oxidation, intensity of lipoperoxidation processes and antioxidant defences in the liver of rats with low (LR) and high (HR) resistance to hypoxia to elucidate the mechanisms of action of L-arginine and the NO synthase inhibitor L-NNA before or after exposure to lead nitrate. Results: Our study suggests that the redistribution of oxygen-dependent processes towards mitochondrial processes under the influence of the nitric oxide precursor amino acid L-arginine is an important mechanism for maintaining mitochondrial respiratory chain function during per os lead nitrate exposure (3.6 mg lead nitrate/kg bw per day for 30 days). Animals were given L-arginine at a dose of 600 mg/kg bw (i.p., 30 min) before and after exposure to lead nitrate or the NO synthase inhibitor Nω-nitro-L-arginine (L-NNA) at a dose of 35 mg/kg bw (i.p., 30 min) before and after exposure to lead nitrate. Our experiments demonstrated the efficacy of using lead nitrate to simulate lead-related toxic processes via Pb levels in liver tissue; we demonstrated significantly reduced levels of nitrites and nitrates, i.e. stable metabolites of the nitric oxide system, in both LR and HR animals. The effect of the amino acid L-arginine stabilised the negative effects of lead nitrate exposure in both groups of LR and HR rats. We observed the efficiency of mitochondrial energy supply processes and showed a greater vulnerability of NADH-dependent oxidation during lead nitrate exposure in the liver of HR rats. Conclusion: L-arginine initiated the processes of oxidation of NADH-dependent substrates in the LR group, whereas in the HR group this directionality of processes was more effective when the role of the nitric oxide system was reduced (use of L-NNA). Our study of key antioxidant enzyme activities in rat liver tissue during lead nitrate exposure revealed changes in the catalase-peroxidase activity ratio. We found different activities of antioxidant enzymes in the liver tissue of rats treated with lead nitrate and L-arginine or L-NNA, with a significant increase in GPx activity in the LR group when L-arginine was administered both before and after exposure to lead nitrate.

Adaptive Effects of Intermittent Hypoxia Training on Oxygen-Dependent Processes as a Potential Therapeutic Strategy Tool

Background/Aims: Important benefits of intermittent hypoxic training (IHT) have emerged as an effective tool for enhancing adaptive potential in different pathological states, among which acute hypoxia dominates. Therefore, the aim of our study was to evaluate the mechanisms related to the effects of the nitric oxide system (nitrites, nitrates, carbamide, and total polyamine content) on ADP-stimulated oxygen consumption and oxidative phosphorylation in heart and liver mitochondria and biomarkers of oxidative stress in the blood, heart, and liver of rats exposed to the IHT method and acute hypoxia and treated with the amino acid L-arginine (600 mg/kg, 30 min) or the NO synthase inhibitor L-NNA (35 mg/kg, 30 min) prior to each IHT session. Methods: We analysed the modulation of the system of oxygen-dependent processes (mitochondrial respiration with the oxygraphic method, microsomal oxidation, and lipoperoxidation processes using biochemical methods) in tissues during IHT in the formation of short-term and long-term effects (30, 60, and 180 days after the last IHT session) with simultaneous administration of L-arginine. In particular, we investigated how mitochondrial functions are modulated during intermittent hypoxia with the use of oxidation substrates (succinate or α-ketoglutarate) in bioenergetic mechanisms of cellular stability and adaptation. Results: The IHT method is associated with a significant increase in the production of endogenous nitric oxide measured by the levels of its stable metabolite, nitrite anion, in both plasma (almost 7-fold) and erythrocytes (more than 7-fold) of rats. The intensification of nitric oxide-dependent pathways of metabolic transformations in the energy supply processes in the heart and liver, accompanied by oscillatory mechanisms of adaptation in the interval mode, causes a probable decrease in the production of urea and polyamines in plasma and liver, but not in erythrocytes. The administration of L-arginine prior to the IHT sessions increased the level of the nitrite-reducing component of the nitric oxide cycle, which persisted for up to 180 days of the experiment. Conclusion: Thus, the efficacy of IHT and its nitrite-dependent component shown in this study is associated with the formation of long-term adaptive responses by preventing the intensification of lipoperoxidation processes in tissues due to pronounced changes in the main enzymes of antioxidant defence and stabilisation of erythrocyte membranes, which has a pronounced protective effect on the system of regulation of oxygen-dependent processes as a whole.

Tricarboxylic Acid Cycle Intermediates and Individual Ageing.

Anti-ageing biology and medicine programmes are a focus of genetics, molecular biology, immunology, endocrinology, nutrition, and therapy. This paper discusses metabolic therapies aimed at prolonging longevity and/or health. Individual components of these effects are postulated to be related to the energy supply by tricarboxylic acid (TCA) cycle intermediates and free radical production processes. This article presents several theories of ageing and clinical descriptions of the top markers of ageing, which define ageing in different categories; additionally, their interactions with age-related changes and diseases related to α-ketoglutarate (AKG) and succinate SC formation and metabolism in pathological states are explained. This review describes convincingly the differences in the mitochondrial characteristics of energy metabolism in animals, with different levels (high and low) of physiological reactivity of functional systems related to the state of different regulatory systems providing oxygen-dependent processes. Much attention is given to the crucial role of AKG and SC in the energy metabolism in cells related to amino acid synthesis, epigenetic regulation, cell stemness, and differentiation, as well as metabolism associated with the development of pathological conditions and, in particular, cancer cells. Another goal was to address the issue of ageing in terms of individual characteristics related to physiological reactivity. This review also demonstrated the role of the Krebs cycle as a key component of cellular energy and ageing, which is closely associated with the development of various age-related pathologies, such as cancer, type 2 diabetes, and cardiovascular or neurodegenerative diseases where the mTOR pathway plays a key role. This article provides postulates of postischaemic phenomena in an ageing organism and demonstrates the dependence of accelerated ageing and age-related pathology on the levels of AKG and SC in studies on different species (roundworm Caenorhabditis elegans, Drosophila, mice, and humans used as models). The findings suggest that this approach may also be useful to show that Krebs cycle metabolites may be involved in age-related abnormalities of the mitochondrial metabolism and may thus induce epigenetic reprogramming that contributes to the senile phenotype and degenerative diseases. The metabolism of these compounds is particularly important when considering ageing mechanisms connected with different levels of initial physiological reactivity and able to initiate individual programmed ageing, depending on the intensity of oxygen consumption, metabolic peculiarities, and behavioural reactions.

Abstract B051: Investigating lipid homeostasis in pancreatic ductal adenocarcinoma under tumor-like stress

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a 5-year survival rate of only 10%. One hallmark of PDAC’s tumor microenvironment is dense desmoplasia, due to abnormal accumulation of extracellular matrix and proliferative fibroblasts. During tumorigenesis, pancreatic stellate cells (PSCs) obtain myofibroblast-like signatures and contribute to the fibrotic environment of PDAC. Desmoplasia-induced hypovascularity severely limits oxygen and nutrient delivery. Our laboratory revealed that hypoxia is prominent even at the pancreatic intraepithelial neoplasia (PanIN) stage, a dominant precursor lesion of PDAC. Hypoxia inhibits oxygen-dependent metabolic processes. For example, unsaturated lipid biosynthesis relies on oxygen to maintain desaturase enzymatic activities. Hypoxia also stimulates lipid uptake. Previous studies demonstrated that RAS-transformed cells preferentially import unsaturated lysophosphatidylcholines (LPCs) from culture media. However, in a nutrient-limited fibrotic environment, the potential source of lipids is unclear. Interestingly, a lipidomic study of a PSC secretome displayed a significant amount of LPCs, suggesting that PSCs are the potential lipid source in the PDAC microenvironment. Our data indicate that exogenous unsaturated lipids sustain PDAC cell viability under hypoxia and nutrient deficiency. Moreover, we find PDAC cell survival under tumor-like stress is enhanced in PSC conditioned medium, but not in delipidated conditioned medium. Strikingly, we show that cancer-associated fibroblasts do not experience hypoxic stress as much as adjacent malignant epithelium cells in vivo, suggesting cancer-associated fibroblasts provide unsaturated (and other) lipids to PDAC cells. Based on our lipidomic mass spectra of PSC conditioned medium, we determined that LPCs are actively utilized by PDAC cells for phosphatidylcholine and triglyceride regeneration. By inhibiting LPC to PC conversion with the drug TSI-01, which targets LPCAT (acyltransferase), unsaturated LPC no longer sustains cancer cell survival and ER stress is reactivated. In this study, we demonstrated metabolic crosstalk between fibroblasts and PDAC cells under stress conditions. Our findings revealed a novel metabolic inhibitor to disrupt the metabolic crosstalk between PSC and pancreatic cancer cells which might benefit developing combinatorial therapy of PDAC. Citation Format: Xu Han, Michelle Burrows, Laura Kim, Clementina Mesaros, John Tobias, Brian Keith, Celeste Simon. Investigating lipid homeostasis in pancreatic ductal adenocarcinoma under tumor-like stress [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B051.

Quantitative Caffeine Analysis in Robusta Coffee Utilizing Amperometric Biosensing Technology

Consuming caffeine in inappropriate amounts can disrupt various aspects, especially health. Controlling intake by knowing the caffeine levels in coffee is necessary to reduce the potential negative impacts. This research focuses on the detection of caffeine in Robusta coffee at two different concentrations (1:10 and 1:20 g/mL) and its relationship with yeast metabolism. An amperometric biosensor with a transimpedance amplifier to measure caffeine levels is used which has the advantages of sensitivity, cost-effectiveness, real time monitoring, biocompatibility, and reliable measurements. The data were statistically analyzed using ANOVA and visualized using Principal Component Analysis (PCA). The results revealed a concentration -dependent decrease in biosensor readings as caffeine levels increased (0.1, 0.5, 1, 1.5, and 2 mM), indicating caffeine's ability to inhibit yeast oxygen consumption and oxygen-dependent metabolic processes. The sensitivity of the biosensor in detecting caffeine is 36.66 mV/mM. PCA uncovered complex patterns, relationships, and variations within the caffeine data. PC1 and PC2, the first two principal components, collectively explained 86.3% of the data's variance. Eigenvalues for both PCs were greater than 1, highlighting their significance in understanding the dataset's complexity. This research enhances our understanding of caffeine content in Robusta coffee and its effects on yeast metabolism, providing valuable insights for the coffee industry. This use of yeast biosensors offers efficiency, and adaptability that make that biosensor valuable in a variety of scientific and industrial contexts.

Do the Effects of Krebs Cycle Intermediates on Oxygen-Dependent Processes in Hypoxia Mediated by the Nitric Oxide System Have Reciprocal or Competitive Relationships?

Currently, it is proven that the cellular metabolism of nitric oxide is necessary to maintain optimal health and adaptation of the organism to the impact of various environmental factors. The aim of this work was to reveal the biological role of nitric oxide, its metabolic changes, and its mechanism of action in tissues under hypoxia, as well as the possibility of tissue metabolism correction through NO-dependent systems under the influence of Krebs cycle intermediates. A systematic assessment of the effect of succinate (SC, 50 mg/kg b.w.) and α-ketoglutarate (KGL, 50 mg/kg b.w.) in the regulation of oxygendependent processes in rats (mitochondrial oxidative phosphorylation, microsomal oxidation, intensity of lipid peroxidation processes, and the state of the antioxidant defense system) depending on functional changes in nitric oxide production during hypoxia was evaluated. The state of the nitric oxide system was estimated spectrophotometrically by determination of the concentration of its stable nitrite anion metabolite (NO2 -). The levels of catecholamines were estimated from the content of epinephrine and norepinephrine using the differentially fluorescent method. The activity of cytochrome P450-dependent aminopyrine-N-demethylase was determined with the Nash reagent. Tissue hypoxia and metabolic disorders caused by this condition through changes in the content of catecholamines (epinephrine, norepinephrine, dopamine, DOPA) as well as the cholinesterase-related system (acetylcholine content and acetylcholinesterase activity) were the studied experimental parameters under acute hypoxia (AH, 7% O2 in N2, 30 min). The activation of lipid peroxidation and oxidatively modified proteins and an increase in the epinephrine content in AH are associated with an increased role of SC and a decrease in KGL as substrates of oxidation in mitochondria. A more pronounced effect of exogenous KGL, compared to SC, on the content of nitrite anion as a stable metabolite of nitric oxide in the liver under acute hypoxia against the background of a decrease in the intensity of lipid peroxidation processes was revealed. The activation of SC-dependent mitochondrial oxidative processes caused by AH was found to decrease in animals after an intermittent hypoxia training (IHT) course. IHT (7% O2 in N2, 15-min, 5 times daily, 14 days) prevented the activation of oxidative stress in tissues and blood after the AH impact and increased the efficiency of energy-related reactions in the functioning of hepatic mitochondria through increased oxidation of KGL. The studied effects of adaptation are mediated by an increase in the role of NO-dependent mechanisms, as assessed by changes in the pool of nitrates, nitrites, carbamides, and total polyamines.

A STUDY OF THE EFFECT OF SAUNA ON THE OXYGEN TRANSPORT FUNCTION OF YOUNG ATHLETES ENGAGED IN HANDBALL SPORT

The effect of sauna on blood oxygen transport function, lipid peroxidation, prooxidant-antioxidant balance in athletes aged 17-21 engaged in handball sport was studied in the article. Persons involved in the hot air sauna were exposed once a week (20 procedures) for a period of four months. The sauna procedure (at 85-90°C, 10-15% humidity) consisted of two parts: 5 and 10 minutes. In young handball athletes, after taking a dry air bath, an increase in pO2, which is the development of respiratory alkolosis, and a decrease in the combination of hemoglobin and oxygen in venous blood increased the amount of oxygen transported to tissues. After a one-time exposure to the sauna, the development of oxidative stess accelerated (intensification of free radical processes, weakening of antioxidant defenses), and at the end of the course it began to decline. The observed increase in the formation of nitric oxide can play an important role in the modification of oxygen-dependent processes in the body.

Oxygen-Dependent Blood Processes in Beck's Sarcoidosis

The objective: to assess the state of oxygen-dependent blood processes in patients with Beck's sarcoidosis.Subjects and Methods. Parameters of blood oxygen transport function and free radical lipid oxidation, as well as the content of nitrogen monoxide and hydrogen sulfide gas transmitters were assessed in the blood of 75 patients (41 women; 34 men) with Beck's sarcoidosis, stage 2 (the pulmonary mediastinal form).Results. In the pulmonary mediastinal form of sarcoidosis versus healthy individuals, there was a decrease in the degree of blood oxygen saturation from 65.4 (60.6; 67.8) to 41.50 (36.0; 49.8), p < 0.05, %, partial oxygen pressure from 40.0 (38.0; 47.0) to 23.0 (18.3; 29.0) mmHg, p < 0.05, and blood pH increased. A decrease in the index of hemoglobin affinity to oxygen p50real (26.80 (24.70; 31.40), p < 0.05, versus healthy individuals 28.2 (27.9; 29.1) mmHg) was revealed. The level of diene conjugates increased in plasma by 86.4% (p < 0.05) and malondialdehyde increased in erythrocytes by 139.2% (p < 0.05), while the following parameters decreased: α-tocopherol (by 42.7 %, p < 0.05), retinol (by 41.9%, p < 0.05), reduced glutathione (by 30.4%, p < 0.05), and ceruloplasmin (by 22.3%, p < 0.05) in plasma. There was an increase in the concentration of nitrogen monoxide (from 15.42 (14.48; 17.71) to 17.09 (7.04; 25.09), mmol/L) and a decrease in hydrogen sulfide (from 29.01 (25.21; 37.03) to 13.08 (8.63; 20.46), mmol/L) in the blood in case of this pathology.Conclusion. There is a deterioration in the blood oxygen-binding properties in patients with Beck's sarcoidosis, stage 2, and as a consequence, tissue needs in oxygen are not adequately provided by blood circulation. There is an increase in the concentration of nitrogen monoxide and a decrease in hydrogen sulfide, which affects the oxygen transport function of blood which may be important for ensuring the processes of oxygen transfer to tissues. In this pathology, activation of lipid peroxidation and a decrease in the level of antioxidant protection factors of blood were revealed which might be important for the genesis of this disease.

Cystic transformation of the pineal gland: clinical features and laboratory analysis of saliva and blood

Objective: to determine the content of melatonin and indicators of antihypoxic resistance, the state of antioxidant protection according to the determination of the level of lactate, pyruvate and indicators of the glutathione system (glutathione reductase and glutathione peroxidase) in patients with cystic transformation of the pineal gland (CSG).Materials and methods: during the period from January 2015 to December 2016, 5930 patients were examined, including 300 people with cystic transformation of the pineal gland. 56 people were selected for laboratory examination. The age of the examined patients ranged from 25 to 43 years. Of these, 37 people with cystic transformation of the pineal gland (CSG): 20 women — people, and men — 17 people, 19 people — the control group. The data obtained were considered both in relation to the general group of patients with this disease, and in relation to the division according to gender (men, women), and the volume of HTCW (“large”, “small”).Results: in the general group of patients, an increase in the content of melatonin in saliva and blood was recorded in all portions. Against this background, the aerobic direction of metabolism prevailed, the processes of consumption and restoration of reduced glutathione increased, which indicates the activation of the mechanisms of adaptive-compensatory restructuring of the functional state of the body.Conclusion: melatonin production in patients with cystic transformation of the pineal gland is correlated with the size of the cysts, with the most pronounced production being recorded at night. In women, to a greater extent than in men, signs of stimulation of oxygen-dependent processes are found, which indicates the intensity of adaptive reactions and the elimination of toxic products in response to stress associated with the presence of cysts.

Oxygen-Dependent Adaptation Processes in a Human Organism in Normal Living Conditions and during Space Flight

Oxygen-Dependent Adaptation Processes in a Human Organism in Normal Living Conditions and during Space Flight

Characteristics of Oxygen-Dependent Processes in Pulmonary Tuberculosis and Their Dynamics in the Course of Complex Treatment

In conditions of tuberculous inflammation, decompensation occurs in the system of peroxidation – antioxidant protection, in which the mechanisms of oxygen transport by blood play an important role. Many pathogenetic links in the development of Tuberculosis (TB) lungs insufficiently studied, in particular, of blood Oxygen Carrying (OC) of blood.

Abstract PR024: Investigating lipid homeostasis in pancreatic ductal adenocarcinoma under tumor-like stress

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a 5-year survival rate of only 10%. One hallmark of PDAC’s tumor microenvironment is dense desmoplasia, due to abnormal accumulation of extracellular matrix and proliferative fibroblasts. During tumorigenesis, pancreatic stellate cells (PSCs) obtain myofibroblast-like signatures and contribute to the fibrotic environment of PDAC. Desmoplasia-induced hypovascularity severely limits oxygen and nutrient delivery. Our laboratory revealed that hypoxia is prominent even at the pancreatic intraepithelial neoplasia (PanIN) stage, a dominant precursor lesion of PDAC. Hypoxia inhibits oxygen-dependent metabolic processes. For example, unsaturated lipid biosynthesis relies on oxygen to maintain desaturase enzymatic activities. Hypoxia also stimulates lipid uptake. Previous studies demonstrated that RAS-transformed cells preferentially import unsaturated lysophosphatidylcholines (LPCs) from culture media. However, in a nutrient-limited fibrotic environment, the potential source of lipids is unclear. Interestingly, a lipidomic study of a PSC secretome displayed a significant amount of LPCs, suggesting that PSCs are the potential lipid source in the PDAC microenvironment. Our data indicate that exogenous unsaturated lipids sustain PDAC cell viability under hypoxia and nutrient deficiency. Moreover, we find PDAC cell survival under tumor-like stress is enhanced in PSC conditioned medium, but not in delipidated conditioned medium. Strikingly, we show that cancer-associated fibroblasts do not experience hypoxic stress as much as adjacent malignant epithelium cells in vivo, suggesting cancer-associated fibroblasts provide unsaturated (and other) lipids to PDAC cells. Based on our lipidomic mass spectra of PSC conditioned medium, we determined that LPCs are actively utilized by PDAC cells for phosphatidylcholine and triglyceride regeneration. To discover novel therapeutic strategies, we performed small molecule screens to identify potential drugs that disrupt LPC uptake and metabolism by PDAC cells. Our overall hypothesis is that activated PSCs (and potentially other fibroblasts) support PDAC cell survival by providing lipids, particularly LPCs, and inhibition of LPC utilization by cancer cells or unsaturated lipid synthesis by PSCs induces PDAC cell death under metabolically challenging conditions. In summary, this project aims to demonstrate metabolic crosstalk between fibroblasts and PDAC cells under stress conditions. The key advance of my research is that activated PSCs suppress PDAC cell death by supplying tumor cells with unsaturated LPCs for the maintenance of lipid homeostasis, in a hypoxic and nutrient-poor environment. If true, our findings will reveal novel metabolic targets for developing combinatorial therapy of PDAC. Citation Format: Xu Han, Michelle Burrows, Yanqing Jiang, Clementina Mesaros, David Schultz, Brian Keith, Celeste Simon. Investigating lipid homeostasis in pancreatic ductal adenocarcinoma under tumor-like stress [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr PR024.

Modulatory Contribution of Oxygenating Hydrogels and Polyhexamethylene Biguanide on the Antimicrobial Potency of Neutrophil-like Cells.

Neutrophils are a first line of host defense against infection and utilize a series of oxygen-dependent processes to eliminate pathogens. Research suggests that oxygen availability can improve anti-infective mechanisms by promoting the formation of reactive oxygen species. Also, oxygen can synergistically upregulate the antibacterial properties of certain antibiotics against bacteria by altering their metabolism and causing an increase in the antibiotic uptake of bacteria. Therefore, understanding the effects of oxygen availability, as provided via a biomaterial treatment alone or along with potent antibacterial agents, on neutrophil functions can lead us to the development of new anti-inflammatory and anti-infective approaches. However, the study of neutrophil functions in vitro is often limited by their short life span and nonreproducibility, which suggests the need for cell line-based models as a substitute for primary neutrophils. Here, we took advantage of the differentiated human leukemia-60 cell line (HL-60), as an in vitro neutrophil model, to test the effects of local oxygen and antibacterial delivery by fluorinated methacrylamide chitosan (MACF) hydrogels incorporated with polyhexamethylene biguanide (PHMB) antibacterial agent. Considering the natural modes of neutrophil actions to combat bacteria, we studied the impact of our dual functioning oxygenating-antibacterial platforms on neutrophil phagocytosis and antibacterial properties as well as the formation of neutrophil extracellular traps (NETs) and reactive oxygen species (ROS). Our results demonstrated that supplemental oxygen and antibacterial delivery from MACF-PHMB hydrogel platforms upregulated neutrophil antibacterial properties and ROS production. NET formation by neutrophils upon treatment with MACF and PHMB varied when chemical and biological stimuli were used. Overall, this study presents a model to study immune responses in vitro and lays the foundation for future studies to investigate if similar responses also occur in vivo.

In Vivo Evidence of Single 13C and 15N Isotope-Labeled Methanotrophic Nitrogen-Fixing Bacterial Cells in Rice Roots.

ABSTRACTMethane-oxidizing bacteria (methanotrophs) play an ecological role in methane and nitrogen fluxes because they are capable of nitrogen fixation and methane oxidation, as indicated by genomic and cultivation-dependent studies. However, the chemical relationships between methanotrophy and diazotrophy and aerobic and anaerobic reactions, respectively, in methanotrophs remain unclear. No study has demonstrated the cooccurrence of both bioactivities in a single methanotroph bacterium in its natural environment. Here, we demonstrate that both bioactivities in type II methanotrophs occur at the single-cell level in the root tissues of paddy rice (Oryza sativa L. cv. Nipponbare). We first verified that difluoromethane, an inhibitor of methane monooxygenase, affected methane oxidation in rice roots. The results indicated that methane assimilation in the roots mostly occurred due to oxygen-dependent processes. Moreover, the results indicated that methane oxidation-dependent and methane oxidation-independent nitrogen fixation concurrently occurred in bulk root tissues. Subsequently, we performed fluorescence in situ hybridization and NanoSIMS analyses, which revealed that single cells of type II methanotrophs (involving six amplicon sequence variants) in paddy rice roots simultaneously and logarithmically fixed stable isotope gases 15N2 and 13CH4 during incubation periods of 0, 23, and 42 h, providing in vivo functional evidence of nitrogen fixation in methanotrophic cells. Furthermore, 15N enrichment in type II methanotrophs at 42 h varied among cells with an increase in 13C accumulation, suggesting that either the release of fixed nitrogen into root systems or methanotroph metabolic specialization is dependent on different microenvironmental niches in the root.

CHANGES IN PROTEIN AND LIPID PEROXIDATION IN ORGANS OF HEPATOPANCREATOBILIARY SYSTEM, ENZYMATIC ANTIOXIDANTS IN RATS UNDER THE CONDITIONS OF DIETS WITH EXCESSIVE CARBOHYDRATES OR FATS

Among the mechanisms of pathological processes development, in particular obesity, an important role belongs to the increase in the intensity of oxygen-dependent processes. It is known that the products of protein and lipid peroxidation can change the structure of the cell membrane, lead to denaturation of proteins and damage to amino acids. Accumulation of protein and lipid peroxidation products can inhibit oxidative phosphorylation and glycolysis, can cause tissue edema and worsen the course of inflammatory processes. Such changes may occur against the background of inertia or suppression of antioxidant reserves. The in-depth study of the obesity development against the background of high-carbohydrate or high-fat diets attracts attention.
 The aim of the research was to study the peculiarities of indices of the oxygen-dependent processes and anti-radical protection of the body against the background of a high-calorie diet during the experiment. The study was performed using mature male rats on a diet with excessive amount of carbohydrates (experimental group 1) and fats (experimental group 2) and on a standard diet of vivarium (control group).
 As a result of the study in the blood serum of experimental rats there was observed an increased content of products of the oxidative modification of proteins in the blood serum at 64.35% – 3.3-fold (p˂0.05), in liver tissues – 2.6-4.5-fold (p˂0.01) and pancreas at 67.86% – 5.6-fold (p˂0.05) regarding the control group data. Changes in lipoperoxidation indices were unidirectional. In particular, in the blood serum of animals on high-carbohydrate and high-fat diets there was an increase in the content of diene conjugates (DC) and products that react to thiobarbituric acid (TBA-AP) at 72.37% – 2.2-fold (p˂0.001), in the tissues of liver and pancreas – an increase in the level of TBA-AP at 44.07% – 6.0-fold (p˂0.01), respectively regarding the control. There were no significant differences found between the studied indices of protein and lipid peroxidation in animals of the experimental groups 1 and 2. The resulting changes may indicate a number of abnormalities (structural rearrangement of hepatocyte membranes, impaired cellular metabolism and energy metabolism, increased unsaturated fatty acids), which in turn can lead to the development of diabetes mellitus and obesity.
 Activation of protein and lipid peroxidation occurred under the conditions of increased catalase activity at 2.5-3.4-fold (p˂0.05), ceruloplasmin content at 54,61-88,65% (р˂0,05), iron transferrin saturation at 43,58-51,28% (р˂0,01) against the background of reduced superoxide dismutase and glutathione reductase activity (at 26,84-83,34% р˂0,01) regarding the values in intact animals. The determined changes of antioxidant reserve did not depend on the diet type. Such changes may indicate a corresponding strain on the functional abilities of the antioxidant system during the increase in the intensity of oxidative stress under the conditions of obesity.
 The resulting disorders reflect the development of oxidative stress and are the risk factors for structural adjustments and functional changes in the hepatopancreatobiliary system organs. Activation of the processes of free radical oxidation of proteins and lipids against the background of inhibition of antioxidant enzymes can play a significant role in the development of obesity complications, especially such as hypertension, atherosclerosis, heart failure, type 2 diabetes mellitus.

Influence of Eearly Necrectomy in Pregnant Rats with Deep Thermal Skin Burns on Maternal Oxygen-Dependent Processes and Further Course of Pregnancy

Influence of Eearly Necrectomy in Pregnant Rats with Deep Thermal Skin Burns on Maternal Oxygen-Dependent Processes and Further Course of Pregnancy

Ursolic acid as a potential inhibitor of Mycobacterium tuberculosis cytochrome bc1 oxidase-a molecular modelling perspective.

The escalating burden of tuberculosis disease and drastic effects of current medicine has stimulated a search for alternative drugs. A medicinal plant Warburgia salutaris has been reported to possess inhibitory properties against M. tuberculosis. In this study, we apply computational methods to investigate the probability of W. salutaris compounds as potential inhibitors of M. tuberculosis QcrB protein. We performed molecular docking, molecular dynamics simulations, radius of gyration, principal component analysis (PCA), and molecular mechanics-generalized born surface area (MM-GBSA) binding-free energy calculations in explicit solvent to achieve our objective. The results suggested that ursolic acid (UA) and ursolic acid acetate (UAA) could serve as preferred potential inhibitors of mycobacterial QcrB compared to lansoprazole sulphide (LSPZ) and telacebec (Q203)-UA and UAA have a higher binding affinity to QcrB compared to LSPZ and Q203 drugs. UA binding affinity is attributed to hydrogen bond formation with Val120, Arg364 and Arg366, and largely resonated from van der Waals forces resulting from UA interactions with hydrophobic amino acids in its vicinity. UAA binds to the porphyrin ring binding site with higher binding affinity compared to LSPZ. The binding affinity results primarily from van der Waals forces between UAA and hydrophobic residues of QcrB in the porphyrin ring binding site where UAA binds competitively. UA and UAA formed stable complexes with the protein with reduced overall residue mobility, consequently supporting the magnitude of binding affinity of the respective ligands. UAA could potentially compete with the porphyrin ring for the binding site and deprive the mycobacterial cell from oxygen, consequently disturbing mycobacterial oxygen-dependent metabolic processes. Therefore, discovery of a compound that competes with porphyrin ring for the binding site may be useful in QcrB pharmocological studies. UA proved to be a superior compound, although its estimated toxicity profile revealed UA to be hepatotoxic within acceptable parameters. Although preliminary findings of this report still warrant experimental validation, they could serve as a baseline for the development of new anti-tubercular drugs from natural resources that target QcrB.

Features of ozone effect on the oxygen-dependent blood processes under hypercapnia conditions

The aim of this work is to study of ozone effect on blood oxygen-dependent processes under hypercapnia conditions. The studied blood samples are pretreated with a hypercapnic gas mixture followed by the addition of ozonized isotonic sodium chloride solution (with an ozone concentration of 6 mg/l), as well as gaseous transmitters donors, nitroglycerin and sodium hydrosulfide. It has been established that hypercapnia enhanced the ozone effect on the blood oxygen transport function and was characterized by the oxyhemoglobin dissociation curve shift to the right, also increased hydrogen sulfide synthesis and absence of changes in the nitrates/nitrites concentration. Under these conditions nitroglycerin and sodium hydrosulfide did not change the parameters of the blood gas transport function, but increased the level of nitrate/nitrite and hydrogen sulfide. Preliminary hypercapnia does not eliminate the activating effect of ozone on the free radical oxidation processes, and the addition of the applied gaseous transmitter donors does not contribute to the regulation of the studied parameters.