Decreased Lactate Dehydrogenase Activity Research Articles

The Antibacterial Efficacy and Mechanism of Tea Polyphenol Against Drug-Resistant Aeromonas veronii TH0426 In Vitro.

The emergence of Motile Aeromonas Septicemia (MAS) caused by Aeromonas veronii in sturgeon farming has become a significant concern due to its high mortality impact on the aquaculture industry. The threat posed by MAS highlights the urgent need for effective control measures to combat bacterial infections in sturgeon populations. Tea polyphenol (TP) has demonstrated promising antibacterial properties against livestock and poultry bacterial infections. However, its antibacterial efficacy and mechanism in bacterial diseases of aquatic animals remain largely unexplored. This study aimed to investigate the in vitro antibacterial effect and mechanism of TP on fish-borne drug-resistant A. veronii TH0426 by assessing the impact of TP on TH0426 cell growth, antibiofilm activity, morphology, as well as measuring electrical conductivity, DNA extravasation, lactate dehydrogenase (LDH) activity, protein, and DNA contents. Results demonstrated that the minimum inhibitory concentration and the minimum bactericidal concentration of TP on TH0426 were 1024 and 2048 μg/mL, respectively. After a 4 h treatment, the growth of TH0426 was completely inhibited at the concentration of 1024 and 2048 μg/mL of TP. Meanwhile, TP exhibited a significant antibiofilm activity. Both scanning electron microscope and transmission electron microscope analyses revealed disrupted cell membrane structure, irregular cell morphology, and loss of intracellular contents following TP treatment. Moreover, increased cell membrane permeability induced by TP led to intracellular ion and DNA leakage, resulting in elevated electrical conductivity and DNA extravasation. Furthermore, TP decreased LDH activity, protein concentration and content, DNA fluorescence intensity, and density in a time-dependent manner, indicating inhibition of protein metabolism and DNA synthesis. In conclusion, TP exhibits potent antibacterial properties by inhibiting biofilm formation, disrupting cell membrane integrity, and interfering with protein metabolism and DNA synthesis in drug-resistant A. veronii TH0426 in vitro.

Biochemical state of brain-liver axis of rats under restraint-induced stress and 2-oxoglutarate impact

Environmental factors play a significant role in affecting the overall health of organisms, with stress being a notable contributor. The process of urbanization and globalization in modern society introduces additional stressors, exacerbating population health issues. Consequently, there is a need for thorough examination, analysis, and exploration of strategies to mitigate the adverse effects of stress. 2-Oxoglutarate, an essential intracellular metabolite and mediator with metabolite trophic properties, emerges as a promising candidate for intervention. In this study, we aimed to evaluate the combined impact of restraint-induced stress and 2-oxoglutarate on the oxidative-reducing balance, antioxidant system effectiveness, and the functional status of the liver and brain in rats. Restraint-induced stress was found to elevate oxidative stress levels, as evidenced by increased concentrations of malonic dialdehyde and oxidative-modified proteins, particularly in the brain. Additionally, signs of lactic acidosis were observed in the liver, indicating physiological changes in response to stress. Furthermore, restraint-induced stress significantly altered bioenergy components, with decreased superoxide dismutase activity and increased cytochrome C concentration, potentially indicating mitochondrial dysfunction and increased membrane permeability. The incorporation of a 2% solution of 2-oxoglutarate into the diet demonstrated a reduction in malonic dialdehyde and carbonylated protein formation, leading to more effective restoration of oxidative-reducing balance in the brain compared to the liver. Additionally, normalization of the lactate/pyruvate concentration ratio and decreased lactate dehydrogenase activity, alongside elevated alanine aminotransferase levels, suggested a decrease in oxidative stress in the liver. Moreover, exogenous 2-oxoglutarate exhibited a positive effect on superoxide dismutase activity and cytochrome C concentration, indicating a reduction in oxidative tension in the liver and progressive mitochondrial function recovery. Based on these findings, exogenous 2-oxoglutarate emerges as a promising metabolitotrope and adaptogen for managing oxidative stress and improving mitochondrial function.

Toxic Trio: Zinc, Copper, and Mercury's Effects on Earthworm Enzymes

The impact of heavy metal exposure on earthworm enzyme activities, specifically lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), xanthine oxidase (XOD), lipid peroxidation, superoxide dismutase (SOD), catalase, and glutathione-S-transferase (GST), was investigated in Perionyx excavatus. In control earthworms, LDH activities were 0.120 µmoles/mg protein/hour in the skin, 0.087 µmoles/mg protein/hour in the ovary, 0.062 µmoles/mg protein/hour in the testis, and 0.096 µmoles/mg protein/hour in the intestine. Exposure to mercuric chloride, copper sulfate, and zinc sulfate resulted in significant decreases in LDH activities by 10% to 19.35%, 4.16% to 22.58%, and 5.74% to 15%, respectively. Similarly, SDH activities declined by 10% to 23% with mercuric chloride, 6.89% to 17.91% with copper sulfate, and 4.13% to 16.66% with zinc sulfate treatments. MDH activities also decreased dramatically across all organs, with statistically significant reductions. GDH activities showed varied responses, while XOD activities uniformly decreased. Lipid peroxidation increased significantly after heavy metal exposure. SOD activities increased with mercuric chloride and copper sulfate, while catalase activities decreased with all three treatments. GST activities were significantly reduced by all treatments, particularly by mercuric chloride and copper sulfate. These findings underscore the substantial impact of heavy metal exposure on earthworm enzyme activities, suggesting potential cellular stress and metabolic disturbances.

Physical and Chemical Parameters in Assessment of Metabolic Profiles of Patients With B

Objective: To study catalytic properties of lactate dehydrogenase (LDH) and some physical and chemical characteristics of blood in patients with thermal injuries.Materials and methods: We examined blood samples from 24 patients with contact burns involving 10%-40% of the body surface area and studied erythrocyte LDH activity in forward and reverse reactions, kinetic characteristics of this process, and protein concentration. We used teziocrystalloscopy to evaluate crystallogenic properties of blood serum of the examined patients with thermal injuries.Results: Thermal injuries were shown to cause a 2-fold decrease in LDH activity in the reverse reaction. Analysis of crystallogenic properties of blood serum of the patients with contact burns revealed that development of a complex response to a burn injury is accompanied by a moderate decrease in the structure index and crystallizability and a signifi decrease in the clearity of the marginal protein zone. In case of burn disease, we also observed a decrease in the initiative potential of the biological fl In addition, microscope slides of the dried blood serum revealed a tendency to randomization of the sample similar to that found in crystalloscopic facies.Conclusions: The local thermal effect leading to a complex response to a burn injury was found to cause significant transformation of physical and chemical characteristics of blood. Thermal injuries cause a decrease in LDH activity in the reverse reaction leading to a disturbance of the lactate-to-pyruvate ratio in the cell and significant shifts in the blood serum composition and properties, which are manifested in a significant change in blood serum crystallogenic and initiating properties.

Mechanism of tetramethylpyrazine attenuates inflammatory injury in endothelial cells by activating the SIRT1 signaling pathway

To study the effects and mechanisms of tetramethylpyrazine (TMP) on tumor necrosis factor-α (TNF-α)-induced inflammatory injury in human coronary artery endothelial cells (HCAEC). HCAEC were randomly divided into four groups: the control group (no treatment), the model group (treated with TNF-α, 50 ng/mL for 24 hours), the TMP group (pre-treated with TMP, 80 μg/mL for 12 hours followed by TNF-α treatment for 24 hours), and the SIRT1 inhibitor group (pre-treated with TMP and the specific SIRT1 inhibitor EX527 for 12 hours followed by TNF-α treatment for 24 hours). Cell viability was assessed using the CCK-8 method, lactate dehydrogenase (LDH) activity was measured using an LDH assay kit, reactive oxygen species (ROS) levels were observed using DCFH-DA staining, expression of pyroptosis-related proteins was detected by Western blot, and SIRT1 expression was analyzed using immunofluorescence staining. Compared to the control group, the model group showed decreased cell viability, increased LDH activity, ROS level and expression of pyroptosis-related proteins, and decreased SIRT1 expression (P<0.05). Compared to the model group, the TMP group exhibited increased cell viability, decreased LDH activity, ROS level and expression of pyroptosis-related proteins, and increased SIRT1 expression (P<0.05). In comparison to the TMP group, the SIRT1 inhibitor group showed decreased cell viability, increased LDH activity, ROS level and expression of pyroptosis-related proteins, and decreased SIRT1 expression (P<0.05). TMP may attenuate TNF-α-induced inflammatory injury in HCAEC, which is associated with the inhibition of pyroptosis and activation of the SIRT1 signaling pathway.

Molecular Mechanism of SOX18 in Lipopolysaccharide-Induced Injury of Human Umbilical Vein Endothelial Cells.

Endothelial dysfunction is associated with the progression of sepsis. This study sought to probe the molecular route of sex-determining region on the Y chromosome-box transcription factor 18 (SOX18) in sepsis-associated endothelial injury. Human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) to establish the sepsis cell model. Cell viability, lactate dehydrogenase (LDH) release, oxidative stress (reactive oxygen species/malondialdehyde/superoxide dismutase), and inflammation (interleukin-1β/tumor necrosis factor-α/interleukin-6) were evaluated by cell counting kit-8 assay and relevant assay kits. The expression levels of SOX18, microRNA (miR)-204-5p, and cadherin-2 (CDH2) in cells were determined by real-time quantitative polymerase chain reaction and Western blot assay. The interaction of SOX18, miR-204-5p, and CDH2 was analyzed by chromatin immunoprecipitation and dual-luciferase assay. LPS induced HUVECs injury and downregulation of SOX18. SOX18 overexpression increased cell viability, while decreased LDH activity, oxidative stress, and inflammation. SOX18 bound to the miR-204-5p promoter to promote miR-204-5p expression, and further repressed CDH2 expression. miR-204-5p knockdown and CDH2 overexpression abrogated the protective role of SOX18 in HUVECs injury. Overall, SOX18 alleviated LPS-induced injury of HUVECs by promoting miR-204-5p and repressing CDH2, suggesting it as a potential target for sepsis treatment.

Mechanism-Based Targeting of Sickle Cell Pathobiology and Pain with Novel Transdermal Curcumin

Pain is a debilitating consequence of sickle cell disease (SCD). We examined the potential of novel topical transdermal curcumin (TDC) gel with transdermal systemic delivery to target pain and SCD pathobiology. Curcumin is an antioxidant and anti-inflammatory polyphenol with therapeutic potential but has poor oral bioavailability. TDC gel (Vasceptor TM, Vascarta Inc.), containing 0.1 M of curcuminoids (derived from Curcugen, Dolcas-Biotech, LLC), or vehicle were applied (0.1 mL) topically by gentle rubbing to the abdomen on alternating days for 3 weeks followed by analysis of blood, organ pathology and skin secretome. Using high-performance liquid chromatography, we found that curcumin levels peaked in the plasma (7.87 µg/mL) and blood cells (6.78 µg/mL) 60 min following administration in C57BL/6 mice, thus, showing efficient bioavailability. Next, we used humanized ‘ sickle‘, homozygous transgenic mice ( HbSS-BERK) expressing &amp;gt;99% human sickle hemoglobin (HbSS) without mouse α- and β-globins. These mice mimic the pathobiology and features of pain observed in persons with SCD. We observed that TDC application in male and female HbSS led to a significant decrease in hyperalgesia over the 21 days (D) of treatment. Mechanical hyperalgesia significantly decreased after 14D of treatment in males and after 21D in females (p&amp;lt;.05 and p&amp;lt;.01, respectively Vs. BL). Similarly, cold hyperalgesia (paw withdrawal frequency on cold plate at 4˚C) decreased significantly in males after 24 hours and in females after 7D of TDC treatment (p&amp;lt;.05 and .01, respectively Vs. BL). Non-evoked cold avoidance showed that males spent significantly more time in the colder chamber at 23ºC on 14D, and females did so on 21D after TDC treatment (p&amp;lt;.001 &amp; p&amp;lt;.01, respectively Vs. BL). Throughout 21D TDC treatment, females showed significantly lower analgesic response in cold hyperalgesia compared to male HbSS, similar to relatively poor response to analgesia in female Vs. male individuals with SCD. The amelioration of hyperalgesia for 21D with TDC suggests a disease-modifying effect. Indeed, we observed a significant increase in hematocrit (p&amp;lt;.05), a reduction in reticulocytes (p&amp;lt;.05), and an appreciable increase (43.2%) in Hb and decreased lactate dehydrogenase activity in the blood of TDC-treated HbSS mice Vs. vehicle (p&amp;lt;.01). RBCs from TDC treated HbSS mice showed enhanced ATP levels (p &amp;lt;.01) and reduced protein carbonylation, both biomarkers of protein oxidation (p&amp;lt;.045) Vs RBCs from vehicle-treated HbSS. Histopathology showed a significant reduction in vascular congestion and iron deposits in TDC-treated male HbSS compared to vehicle in the spleen (p&amp;lt;.0003 &amp; p&amp;lt;.001, respectively) and in % fields involved in hepatic infarcts and iron deposits (p&amp;lt;.02 &amp; p&amp;lt;.044, respectively). Together, decreased hemolysis, increased Hb, hematocrit, and ATP suggest RBC stabilization, improved mitochondrial metabolism, and reduced oxidative stress and organ damage, leading to a disease-modifying effect of TDC. TDC also significantly reduced global inflammatory marker serum amyloid-P (p&amp;lt;.05) and inflammatory cytokines in the skin secretome with a concomitant reduction in interleukins [2 (p&amp;lt;.05), 4 (p&amp;lt;.01), and 6 (p&amp;lt;.01)], monocyte chemoattractant protein 1 (MCP-1; p&amp;lt;.01), interferon-gamma (IFN-γ; p&amp;lt;.05), granulocyte macrophage-colony stimulating factor (GM-CSF; p&amp;lt;.01), and regulated on activation, normal T-cell expressed and secreted protein (RANTES; p&amp;lt;.05) compared to vehicle. MCP-1 contributes to neuropathic pain and inflammation; GM-CSF stimulates granulocyte differentiation and growth. Both RANTES and MCP-1 may also activate mast cells. TDC led to a significant decrease in cutaneous mast cell degranulation (p&amp;lt;.001) Vs. vehicle in sickle mice. These data strongly suggest an anti-inflammatory effect of TDCby targeting the release of cytokines and inhibiting granulocyte activity. TDC significantly ameliorates hyperalgesia (chronic pain), inflammation, hemolysis, oxidative stress, and organ damage and improves mitochondrial function and hematological parameters of SCD pathobiology, indicative of disease modifying and anti-nociceptive effects. The results suggest if started early in life, the use of an easy-to-deploy novel TDC formulation, with increased bioavailability and non-toxic properties that directly target sickle cell pathobiology, may prevent chronic pain in SCD.

Pachymic acid (PA) inhibits ferroptosis of cardiomyocytes via activation of the AMPK in mice with ischemia/reperfusion-induced myocardial injury.

Pachymic acid (PA) is a lanostane-type triterpenoid with various pharmacological effects. However, little is known about the effect of PA on myocardial infarction (MI) induced by ischemia/reperfusion (I/R). In this study, we aimed to investigate the protective effect of PA and its underlying mechanism. A cellular MI model was established by oxygen-glucose deprivation and reperfusion (OGD/R) treatment in HL-1 cardiomyocytes, and we found that OGD/R treatment decreased cell viability and glutathione peroxide (GSH-Px) activity, increased Fe2+ concentration and lactate dehydrogenase (LDH) activity, promoted malondialdehyde (MDA) and reactive oxygen species (ROS) production, and inhibited the expression of ferroptosis marker proteins SLC7A11 and GPX4 in a time-dependent manner. OGD/R-induced HL-1 cells were pretreated with different concentrations of PA (0, 20, 40, 60 μg/mL) for 24 h, and toxicological experiments showed that 150 μg/mL PA decreased cell viability, while low concentrations of PA had no toxic effect on cells. 20 μg/mL PA reversed the inhibitory effect of OGD/R on cell viability, reduced MDA and ROS production, and Fe2+ accumulation, increased GSH-Px activity and the expression of SLC7A11 and GPX4, and decreased LDH activity, especially at 60 μg/mL PA. Meanwhile, PA promoted the phosphorylation of IRS-1, AKT, and AMPK proteins in a dose-dependent manner. AICAR, an AMPK activator, inhibited ferroptosis, while STO-609, an AMPK inhibitor, largely abolished the effect of PA on OGD/R-induced ferroptosis of HL-1 cells. In addition, PA inhibited ferroptosis and myocardial I/R injury in wild-type mice and AMPK knockout (AMPK-/- ) mice. Collectively, PA inhibited ferroptosis of cardiomyocytes through activating of the AMPK pathway, thereby alleviating myocardial I/R injury in mice.

Protective Effects of 2-Methoxyestradiol on Acute Isoproterenol-Induced Cardiac Injury in Rats

Myocardial injury (MI) is an important pathological driver of mortality worldwide., and arises as a result of imbalances between myocardial oxygen demand and supply. In MI, oxidative stress often leads to inflammatory changes and apoptosis. Current therapies for MI are known to cause various adverse effects. Consequently, the development of new therapeutic agents with a reduced adverse event profile is necessary. In this regard, 2-methoxyestradiol (2ME), the metabolic end-product of oestradiol, possesses anti-inflammatory and antioxidant properties. The aim of this research is to assess the impact of 2ME on cardiac injury caused by isoproterenol (ISO) in rats. Animals were separated into six groups; controls, and those receiving 2ME (1 mg/kg), ISO (85 mg/kg), ISO + 2ME (0.25 mg/kg), ISO + 2ME (0.5 mg/kg), and ISO + 2ME (1 mg/kg). 2ME significantly attenuated ISO-induced changes in electrocardiographic changes and the cardiac histological pattern. This compound also decreased lactate dehydrogenase activity, creatine kinase myocardial band and troponin levels. The ability of 2ME to act as an antioxidant was shown by a decrease in malondialdehyde concentration, and the restoration of glutathione levels and superoxide dismutase activity. Additionally, 2ME antagonized inflammation and cardiac cell apoptosis, a process determined to be mediated, at least partially, by suppression of Gal-3/TLR4/MyD88/NF-κB signaling pathway. 2ME offers protection against acute ISO-induced MI in rats and offers a novel therapeutic management option.

The medicinal mushroom Ganoderma lucidum prevents lung tumorigenesis induced by tobacco smoke carcinogens.

Ganoderma lucidum (GL), commonly known as "Lingzhi", is a well-known medicinal mushroom with antioxidant and anti-cancer activity. This study examined the effects of a commercial GL product (GLSF) containing the spore and fruiting body in a 30:8 ratio on tobacco smoke carcinogen-induced lung toxicity and carcinogenesis. The potential chemopreventive effect of GLSF was evaluated in vitro and in vivo. The non-tumorous human bronchial epithelial cells (BEAS-2B cells) were treated with GLSF extract (0.025 and 0.05mg/mL), which significantly blocked malignant transformation induced by benzo[a]pyrene diol epoxide (BPDE) in a dose-dependent manner. To confirm its anti-carcinogenic activity in vivo, the mice were pre-treated with GLSF (2.0g/kg of body weight) or curcumin (100mg/kg of body weight) by oral gavage daily for 7days and then exposed to a single dose of benzo[a]pyrene (B[a]P) (125mg/kg of body weight). The GLSF-treated mice showed a significant reduction in B[a]P-induced lung toxicity, as indicated by decreased lactate dehydrogenase activity, malondialdehyde levels, inflammatory cell infiltration, and improved lung histopathology. We next determined the chemopreventive activity of GLSF in mice which were exposed to two weekly doses of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, 100mg/kg, on the 1st and 8thdays) and fed with control or a modified diet containing GLSF (2.0g/kg) or metformin (250mg/kg) for 33weeks. The GLSF and metformin treatments blocked NNK-induced lung tumor development by decreasing the lung weight, tumor area, and tumor burden compared to the mice exposed to NNK only. GLSF treatment also attenuated the expression of inflammatory, angiogenic, and apoptotic markers in lung tumors. Therefore, GLSF may be used for ameliorating tobacco smoke carcinogens-induced lung toxicity and carcinogenesis.

Hesperetin Alleviates Doxorubicin-Induced Cytotoxicity in H9c2 Cells by Activating SIRT1/NRF2 Signaling

To investigate whether hesperetin (Hes) alleviates doxorubicin (DOX)-induced cardiomyocytotoxicity by reducing oxidative stress via regulating silent information regulator 1 (SIRT1)/nuclear transcription factor E2-related factor 2 (NRF2) signaling in H9c2 cells. H9c2 cells were treated with DOX to establish the cardiotoxicity model and were randomly assigned to four groups, a control group (Control) and three treatment groups, receiving respectively DOX (the DOX group), Hes+DOX (the DOX+Hes group), and Hes+SIRT1 inhibitor EX527+DOX (the DOX+Hes+EX527 group). Cellular morphology was observed by the light microscope. Cell viability was evaluated by CCK-8. DOX-induced apoptosis in H9c2 cells was examined by flow cytometry. The levels of reactive oxygen species (ROS) in the H9c2 cells of the four groups were determied with 2'-7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining. The activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD), catalase (CAT), and SIRT1 as well as the malondialdehyde (MDA) content were measured using ELISA kits. The expressions of cleaved caspase-3, cytochrome c, SIRT1, Ac-FOXO1, NRF2, and heme oxygenase 1 (HO-1) were determined by Western blot. Compared with the Control group, the DOX group showed swollen cellular morphology, decreased cell density and viability, and increased LDH activity in the medium ( P<0.01); both apoptosis and the expression of cleaved caspase-3 and cytochrome c increased ( P<0.01); the activities of CAT and SOD decreased while the contents of MDA and ROS increased ( P<0.01); the expression of SIRT1, NRF2, and HO-1 decreased, the activity of SIRT1 decreased, and the expression of Ac-FOXO1 increased ( P<0.01). Compared with the DOX group, the DOX+Hes group showed improved cellular morphology, increased cell density and viability, and decreased LDH activity in the medium ( P<0.01); the apoptosis and the expression of cleaved caspase-3 and cytochrome c decreased ( P<0.01); the activities of CAT and SOD increased while the levels of MDA and ROS decreased ( P<0.01); the expression of SIRT1, NRF2, and HO-1 increased, the activity of SIRT1 increased, and the expression of Ac-FOXO1 decreased ( P<0.01). Comparison of the findings for the DOX+Hes group and the DOX+Hes+EX527 group showed that EX527 could block the protective effects of Hes against DOX-induced cell injury, oxidative stress, and SIRT1/NRF2 signaling. Hes inhibits oxidative stress and apoptosis via regulating SIRT1/NRF2 signaling, thereby reducing DOX-induced cardiotoxicity in H9c2 cells.

The Effect of Piperidine Nitroxides on the Properties of Metalloproteins in Human Red Blood Cells.

Nitroxides are stable, low molecular-weight radicals containing a nitroxide group that has an unpaired electron. The presence of a nitroxide group determines their redox properties. The effect of the piperidine nitroxides, Tempo, Tempol, and Tempamine, on metalloproteins (hemoglobin, superoxide dismutase, catalase) and lactate dehydrogenase in red blood cells was investigated in this research. In addition, the level of lipid peroxidation and the level of protein carbonyl groups were examined as indicators of the effect of oxidative stress. Nitroxides increased superoxide dismutase activity and oxidized hemoglobin to methemoglobin, and also slightly decreased the catalase activity of red blood cells treated with nitroxides. Tempol significantly decreased lactate dehydrogenase activity. All three nitroxides had no effect on membrane lipid peroxidation and protein oxidation. Our results confirm that nitroxides have both antioxidant and prooxidative effects in human red blood cells. The piperidine nitroxides do not initiate the oxidation of proteins and lipids in the membranes of human red blood cells.

Selenium-enriched Cardamine violifolia protects against sepsis-induced intestinal injury by regulating mitochondrial fusion in weaned pigs.

Sepsis is a life-threatening organ dysfunction caused by the dysregulated response of the host to an infection, and treatments are limited. Recently, a novel selenium source, selenium-enriched Cardamine violifolia (SEC) has attracted much attention due to its anti-inflammatory and antioxidant properties, but little is known about its role in the treatment of sepsis. Here, we found that SEC alleviated LPS-induced intestinal damage, as indicated by improved intestinal morphology, and increased disaccharidase activity and tight junction protein expression. Moreover, SEC ameliorated the LPS-induced release of pro-inflammatory cytokines, as indicated by decreased IL-6 level in the plasma and jejunum. Moreover, SEC improved intestinal antioxidant functions by regulating oxidative stress indicators and selenoproteins. In vitro, TNF-α-challenged IPEC-1 cells were examined and showed that selenium-enriched peptides, which are the main functional components extracted from Cardamine violifolia (CSP), increased cell viability, decreased lactate dehydrogenase activity and improved cell barrier function. Mechanistically, SEC ameliorated LPS/TNF-α-induced perturbations in mitochondrial dynamics in the jejunum and IPEC-1 cells. Moreover, CSP-mediated cell barrier function is primarily dependent on the mitochondrial fusion protein MFN2 but not MFN1. Taken together, these results indicate that SEC mitigates sepsis-induced intestinal injury, which is associated with modulating mitochondrial fusion.

EFFECT OF MODULATION OF NITROGEN OXIDE (II) SYNTHESIS UNDER CHRONIC NORMOBARIC HYPOXIA ON THE ISOENZYME SPECTRUM OF RAT EPIDIDIMIS LACTATE DEHYDROGENASE

Lactate dehydrogenase have a key role in providing energy to cells under physiological and hypoxic conditions. Changes in the activity of the enzyme can be facilitated by nitric oxide (II), regulating the expression of individual fractions of lactate dehydrogenase. Aim. To study changes in the isoenzyme spectrum of rat epididymis lactate dehydrogenase under conditions of hypoxia and modulation of nitric oxide (II) synthesis. Material and methods. Male rats (32) were divided into 4 groups (n=8): 1) chronic normobaric hypoxia; 2) control to group 1; 3) hypoxia together with modeling of nitric oxide deficiency; 4) hypoxia against the background of induction of NO synthesis. The mitochondrial fraction and non-mitochondrial cytoplasm of the head and tail of the epididymis were isolated for laboratory research. The zymogram was obtained by electrophoresis in 7% gel followed by detection by the precipitation reaction of the reduction of nitro blue tetrazolium. The overall activity of lactate dehydrogenase was assessed and the percentage of isoenzyme fractions was calculated. Fractions 1 and X of lactate dehydrogenase were analyzed, the results were con-sidered statistically significant if p 0.05 when comparing two independent samples, and p 0.0167 when comparing three independent samples. Results. Chronic normobaric hypoxia leads to a decrease in lactate dehydrogenase activity compared to the control group. At the same time, the share of the X-fraction of the enzyme and lactate dehydrogenase 1 increases. Modulation of nitric oxide (II) deficiency against the background of hy-poxia increased the activity of the enzyme in the head of the epididymis, where a decrease in the studied fractions of lactate dehydrogenase was ob-served compared to the group of animals subjected only to hypoxia. Stimulation of the synthesis of nitric oxide (II) during hypoxia led to a decrease in the X-fraction, but an increase in the 1st fraction of lactate dehydrogenase in the head of the epididymis, in the tail of the epididymis, opposite changes were observed. Conclusion. Hypoxia causes a change in the ratio of lactate dehydrogenase isoenzymes towards an increase in lactate dehydrogenase B and lactate dehydrogenase X, while a deficiency of nitric oxide (II) contributes to a decrease in lactate dehydrogenase X synthesis.

Plasma exosomes generated by ischaemic preconditioning are cardioprotective in a rat heart failure model

BackgroundExosomes released into the plasma after brief cardiac ischaemia mediate subsequent cardioprotection. Whether donor exosomes can provide cardioprotection to recipients with chronic heart failure, which confers the highest perioperative risk, is unknown. We examined whether ischaemic preconditioning (IPC)-induced plasma exosomes exerted cardioprotection after their transfer from normal donors to post-infarcted failing hearts. MethodsPlasma exosomes were obtained from adult rats after IPC or sham. An exosome inhibitor GW4869 was administrated before IPC in an in vivo model of ischaemia/reperfusion (I/R) injury in normal rats. The IPC exosomes or control exosomes from normal donor rats were perfused to the normal or post-infarcted failing rat hearts before ischaemia in Langendorff perfusion experiments. Infarct size, cardiac enzymes, cardiac function, and pro-survival kinases were quantified. ResultsThe IPC stimulus increased the release of exosomes, whereas GW4869 inhibited the rise of plasma exosomes. Pre-treatment with GW4869 reversed IPC-mediated cardioprotection against in vivo I/R injury. In the Langendorff perfusion experiments, IPC exosomes from normal donor rats reduced mean infarct size from 41.05 (1.87)% to 31.43 (1.81)% and decreased lactate dehydrogenase activity in the post-infarcted failing rat hearts. IPC exosomes but not control exosomes activated pro-survival kinases in the heart tissues. ConclusionsIschaemic preconditioning-induced exosomes from normal rats can restore cardioprotection in heart failure after myocardial infarction, which is associated with activation of pro-survival protein kinases. These results suggest a potential perioperative therapeutic role for ischaemic preconditioning-induced exosomes.

Effects of Endurance Training on Metabolic Enzyme Activity and Transporter Proteins in Skeletal Muscle of Ovariectomized Mice.

Estrogen deficiency or insufficiency can occur under several conditions, leading to negative health outcomes. To establish an effective countermeasure against estrogen loss, we investigated the effects of endurance training on ovariectomy (OVX)-induced metabolic disturbances. Female Institute of Cancer Research mice underwent OVX or sham operations. On day 7 of recovery, the mice were randomized to remain either sedentary or undergo 5 wk of treadmill running (15-20 m·min -1 , 60 min, 5 d·wk -1 ). During week 5 of the training, all animals performed a treadmill running test (15 m·min -1 , 60 min). After the experimental period, OVX resulted in greater gains in body mass, fat mass, and triglyceride content in the gastrocnemius muscle. OVX enhanced phosphofructokinase activity in the plantaris muscle and decreased lactate dehydrogenase activity in the plantaris and soleus muscles. OVX decreased the protein content of NDUFB8, a mitochondrial respiratory chain subunit, but did not decrease other mitochondrial proteins or enzyme activities. Endurance training significantly enhanced mitochondrial enzyme activity and protein content in the skeletal muscles. Although OVX increased the respiratory exchange ratio during the treadmill running test, and postexercise blood lactate levels, endurance training normalized these parameters. The present findings suggest that endurance training is a viable strategy to counteract the negative metabolic consequences in hypoestrogenism.

Thermal tolerance of fish to heatwaves in agricultural streams: What does not kill you makes you stronger?

Abstract Heatwaves are increasing in frequency and intensity under climate change. Freshwater ecosystems are among the most thermally impacted systems, within which agricultural streams are experiencing the most extreme heatwaves and deserve prioritised focus. Heatwaves are approaching the upper thermal limits of many fishes but have received little attention to date. To study whether and how fish tolerate heatwaves from a physiological perspective, we simulated single, multiple, and extended heatwaves at 32 and 34°C in the laboratory, based on high‐resolution summer temperatures recorded in agricultural versus forested streams in Illinois, U.S.A. By investigating the effects of heatwaves on 25°C acclimated fathead minnow Pimephales promelas, an important prey species across North America, we witnessed its high thermal resilience, including a rapid return to metabolic homeostasis after single and multiple heatwaves, measured by oxygen consumption rate. During an extended heatwave, fathead minnow were still able to partially lower oxygen consumption rate after the initial exposure. We also found transient increases in their critical thermal maximum, especially after higher intensity and frequency of heatwaves. However, the thermal resilience of fathead minnow did come with costs, including reduced anaerobic capacity indicated by decreased lactate dehydrogenase activity and impaired antioxidant defence indicated by reduced superoxide dismutase in white muscle. By monitoring metabolic costs and physiological adjustments of fish during and after heatwaves, we showed that fathead minnow were resilient to simulated current and near‐future heatwaves, which may allow them to cope with thermal extremes expected in agricultural streams. Overall, the real‐time monitoring of fish responses to heatwaves incorporates natural dynamics of thermal patterns. It facilitates mechanistic understandings of how fish react to thermal challenges in the real world and offers opportunities to incorporate high‐resolution metabolic costs into future bioenergetic modelling.

Effects of endurance training on metabolic enzyme activity and transporter protein levels in the skeletal muscles of orchiectomized mice

This study investigated whether endurance training attenuates orchiectomy (ORX)-induced metabolic alterations. At 7 days of recovery after sham operation or ORX surgery, the mice were randomized to remain sedentary or undergo 5 weeks of treadmill running training (15–20 m/min, 60 min, 5 days/week). ORX decreased glycogen concentration in the gastrocnemius muscle, enhanced phosphofructokinase activity in the plantaris muscle, and decreased lactate dehydrogenase activity in the plantaris and soleus muscles. Mitochondrial enzyme activities and protein content in the plantaris and soleus muscles were also decreased after ORX, but preserved, in part, by endurance training. In the treadmill running test (15 m/min, 60 min) after 4 weeks of training, orchiectomized sedentary mice showed impaired exercise performance, which was restored by endurance training. Thus, endurance training could be a potential therapeutic strategy to prevent the hypoandrogenism-induced decline in muscle mitochondrial content and physical performance.

Plasma lactate dehydrogenase and pyruvate kinase activity changes with body mass and age across birds and mammals

Abstract Birds and mammals produce most adenosine triphosphate (ATP) through mitochondrial oxidative phosphorylation, but when oxygen is not present in sufficient levels, ATP can be produced through anaerobic glycolysis. Pyruvate kinase (PK) catalyzes the final step of glycolysis by converting phosphoenolpyruvate and adenosine diphosphate (ADP) into pyruvate and ATP. Lactate dehydrogenase (LDH) is important for anaerobic glycolysis by catalyzing the conversion of pyruvate into lactate. In this study, we measured LDH and PK activities in plasma from birds and mammals in order to determine the relationship between LDH and PK with respect to body mass and age. Our results show that birds had a higher LDH and PK activity compared with mammals. There is a positive relationship between body mass and plasma LDH activity in birds only. However, this relationship disappears when the data are phylogenetically corrected. We did not observe a significant relationship between plasma LDH and age in birds or mammals. Plasma PK activity was negatively correlated with body mass in birds but not in mammals and positively associated with age in both birds and mammals. The relationship between LDH and PK with respect to body mass and age may be complex due to differences in metabolism in birds and mammals. Increases in LDH and PK activity with body mass in birds may be linked to anaerobic demands of flight, especially in larger birds. A decrease in LDH activity with age/MLSP (maximum lifespan) in mammals may reflect a differing metabolic shift as compared with birds. Increases in PK with age in both mammals and birds may help them cope with greater energetic needs as cells age.

The Impact of Varying Caffeine‐Induced Contractile Activity on Metabolic Enzyme Activity

Exercise intensity is widely known to differentially affect skeletal muscle metabolic approaches, with a general understanding that short duration, high intensity exercise is associated with an increased reliance on anaerobic glycolysis, while long duration, low to moderate intensity exercise is associated with a greater reliance on aerobic processes. In cell culture, caffeine is a commonly used method to pharmaceutically stimulate contractile activity in skeletal muscle cells; upon exposure to caffeine, ryanodine receptors are stimulated to release calcium, thereby allowing crossbridge cycling and subsequent contractile activity to occur. This technique for exercising muscle cells in culture offers a controlled, experimental platform to study the effect of contractile activity on isolated muscle cells; presumably, varying doses of caffeine should mimic varying levels of exercise intensity, though the degree to which caffeine dose impacts metabolic shifts has yet to be fully elucidated. Here, we exposed C2C12 cells, an immortalized line of mouse skeletal muscle cells, to varying levels of caffeine supplementation throughout myotube differentiation in an attempt to recapitulate metabolic signatures consistent with varying exercise intensities. Following standard proliferation protocols, mature myotubes were differentiated for 7 days. On differentiation days 4‐7, experimental cohorts of cells were exposed to either a low dosage (10mM) or a high dosage (40 mM) of caffeine‐supplemented differentiation media for 20 minutes daily. All cells were harvested for protein on differentiation day seven. Protein concentration across cohorts was measured using a Bradford protein assay. Metabolic changes were characterized by running functional enzyme assays for lactate dehydrogenase (LDH) and citrate synthase (CS) to compare anaerobic and aerobic changes, respectively. Preliminary data suggest that, relative to controls, cells exposed to 10mM caffeine have a decrease in LDH activity, and a trend toward increased CS activity. Conversely, cells exposed to 40mM caffeine show no change in LDH and a trend toward decreased CS activity. Collectively, these preliminary data suggest that C2C12 cells exposed to low doses of caffeine simulating low intensity exercise may have less reliance on anaerobic metabolism with a potential greater reliance on aerobic metabolism, while those exposed to high doses of caffeine simulating high intensity exercise may have a lesser reliance on aerobic metabolism. While more research needs to be done to characterize the precise impact of varying caffeine dosages on C2C12 cells, these initial findings are consistent with previously established trends in exercise intensity and metabolism.