Increased Lactate Dehydrogenase Activity Research Articles

Crowding Effects of Polystyrene Nanoparticles on Lactate Dehydrogenase Activity in Hydra Attenuata.

Plastics pervade our environment and potentially release important quantities of plastic nanoparticles (NPs) from degradation in the environment. The purpose of this study was to examine the crowding effects of polystyrene NPs on lactate dehydrogenase (LDH) in vitro and following exposure to Hydra attenuata. First, LDH activity was measured in vitro in the presence of filamentous (F-)actin and NPs (50 and 100 nm diameter) to determine changes in viscosity and the fractal kinetics of LDH. The fractal dimension (fD) was also determined using the rescaled range analysis procedure. Secondly, these changes were examined in hydra exposed to NPs for 96h to concentrations of NPs. The data revealed that the addition of F-actin increased the rate of LDH at low substrate (pyruvate) concentrations compared to LDH alone with a gradual decrease in the rate with the addition of pyruvate, which is characteristic of the fractal behavior of enzymes in crowded environments. The addition of 50 and 100 nm NPs also produced these changes, which suggest that NPs could change the space properties of the LDH reaction. The fD was reduced to 0.85 and 0.91 with 50 and 100 nm NPs compared to 1.093 with LDH alone. Decrease in the fD was related with increased amplitudes and frequency in viscosity waves in the reaction media. Exposure of hydra to NPs confirmed the increase in LDH activity and the fD was significantly correlated with LDH activity (r = −0.5). Correction of LDH activity (residuals) still revealed an increase in LDH activity in hydra suggesting increased anaerobic metabolism by NPs. In conclusion, the presence of NPs in the intracellular space decreased the fD, which could influence LDH activity in organisms exposed to NPs.

Melatonin protects against myocardial ischemia-reperfusion injury by inhibiting contracture in isolated rat hearts

To investigate the protective effect of melatonin against myocardial ischemia reperfusion (IR) injury in isolated rat hearts and explore the underlying mechanisms. The isolated hearts from 40 male SD rats were randomly divided into 4 groups (n=10): the control group, where the hearts were perfused with KH solution for 175 min; IR group, where the hearts were subjected to global ischemia for 45 min followed by reperfusion for 120 min; IR+melatonin (Mel+IR) group, where melatonin (5 μmol/L) was administered to the hearts 1 min before ischemia and during the first 5 min of reperfusion, followed by 115 min of reperfusion; and IR+2, 3-butanedione monoxime (IR+BDM) group, where the hearts were treated with BDM (20 mmol/L) in the same manner as melatonin treatment. Myocardial injury in the isolated hearts was assessed based on myocardial injury area, caspase-3 activity, and expressions of cytochrome C and cleaved caspase-3 proteins. Cardiac contracture was assessed using HE staining and by detecting lactate dehydrogenase (LDH) activity and the content of cardiac troponin I (cTnI) in the coronary outflow, measurement of left ventricular end-diastolic pressure (LVEDP) and electron microscopy. The content of ATP in the cardiac tissue was also determined. Compared with those in the control group, the isolated hearts in IR group showed significantly larger myocardial injury area and higher caspase-3 activity and the protein expressions of cytochrome C and cleaved caspase-3 with significantly increased LDH activity and cTnI content in the coronary outflow and elevated LVEDP at the end of reperfusion; HE staining showed obvious fractures of the myocardial fibers and the content of ATP was significantly decreased in the cardiac tissue; electron microscopy revealed the development of contraction bands. In the isolated hearts with IR, treatment with Mel or BDM significantly reduced the myocardial injury area, caspase-3 activity, and protein expressions of cytochrome C and cleaved caspase-3, obviously inhibited LDH activity, lowered the content of cTnI and LVEDP, reduced myocardial fiber fracture, and increased ATP content in the cardiac tissue. Both Mel and BDM inhibited the formation of contraction bands in the isolated hearts with IR injury. Mel can alleviate myocardial IR injury in isolated rat hearts by inhibiting cardiac contracture, the mechanism of which may involve the upregulation of ATP in the cardiac myocytes to lessen the tear of membrane and reduce cell content leakage.

Troxerutin attenuates oxygen‑glucose deprivation and reoxygenation‑induced oxidative stress and inflammation by enhancing the PI3K/AKT/HIF‑1α signaling pathway in H9C2 cardiomyocytes.

Myocardial ischemia-reperfusion (MI/R) injury is a complex pathological process that occurs when tissues are reperfused following a prolonged period of ischemia. Troxerutin has been reported to have cardioprotective functions. However, the underlying mechanism by which troxerutin protects against MI/R injury has not been fully elucidated. The aim of the present study was to explore whether troxerutin-mediated protection against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced H9C2 cell injury was associated with the inhibition of oxidative stress and the inflammatory response by regulating the PI3K/AKT/hypoxia-inducible factor-1α (HIF-1α) signaling pathway. The results of the present study suggested that troxerutin pretreatment prevented the OGD/R-induced reduction in cell viability, and the increase in lactate dehydrogenase activity and apoptosis. Troxerutin reversed OGD/R-induced the inhibition of the PI3K/AKT/HIF-1α signaling pathway as demonstrated by the increased expression of PI3K and HIF-1α, and the increased ratio of phosphorylated AKT/AKT. LY294002, a selective PI3K inhibitor, inhibited the PI3K/AKT/HIF-1α signaling pathway and further attenuated the protective effect of troxerutin against OGD/R-induced H9C2 cell damage. Furthermore, small interfering (si)RNA-mediated knockdown of HIF-1α reduced troxerutin-induced protection against OGD/R injury. Troxerutin pretreatment alleviated OGD/R-induced oxidative stress, as demonstrated by the reduced generation of reactive oxygen species and malonaldehyde content, and the increased activities of superoxide dismutase and glutathione peroxidase, which were reduced by HIF-1α-siRNA. Troxerutin-induced decreases in the levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α in OGD/R conditions were also reduced by HIF-1α-siRNA. The results from the present study indicated that troxerutin aggravated OGD/R-induced H9C2 cell injury by inhibiting oxidative stress and the inflammatory response. The primary underlying protective mechanism of troxerutin was mediated by the activation of the PI3K/AKT/HIF-1α signaling pathway.

Combined exposure to hypoxia and ammonia aggravated biological effects on glucose metabolism, oxidative stress, inflammation and apoptosis in largemouth bass (Micropterus salmoides)

Hypoxia and ammonia are unavoidable environmental factors in aquaculture, and have been shown cause various adverse effects in fish. In the present study, a two-factor crossover experiment was carried out to evaluate the combined effect of hypoxia and ammonia on oxidative stress and glucose metabolism endpoints in largemouth bass. The fish were divided into four experimental groups: hypoxia and ammonia group, hypoxia group, ammonia group, and control group. The results showed that hypoxia and ammonia exposures both induced antioxidant response and oxidative stress (superoxide dismutase [SOD] and catalase [CAT] activities increased first then decreased, and malondialdehyde accumulated) and anaerobic glycolysis (increase of blood glucose, decrease of liver glycogen, accumulation of lactate, and increased lactate dehydrogenase activity). In addition, hypoxia and ammonia upregulated antioxidant enzyme genes (Cu/ZnSOD, CAT, and GPx), apoptosis genes (caspase 3, caspase 8, and caspase 9), as well as inflammatory genes (interleukin [IL]-1β and IL-8) and downregulated an anti-inflammatory gene (IL-10), suggesting that apoptosis and inflammation may be related to oxidative stress. The increased expression of GLUT1, LDH, and MCT4 were induced by hypoxia and ammonia, suggesting that anaerobic glycolysis was increased. Furthermore, fish suffering from hypoxia or ammonia exposure showed some changes in gill tissues histology, and the most severe lesions of gill tissues appeared in simultaneous exposure. Overall, both hypoxia and ammonia affected homeostasis, and simultaneous exposure led to more deleterious effects on largemouth bass than exposure to the individual stressors.

Correction of acid base disorders in rats with acute ethylene glycol poisoning

The aim of the article. The aim of this study was to evaluation of the effectiveness of standard antidote therapy and dimephosphon administration in rats with acute ethylene glycol poisoning. The tasks of the study included modeling acute ethylene glycol poisoning in rats, conducting experimental therapy with ethanol antidote in combination with sodium bicarbonate and dimephosphon therapy, comparing the effectiveness of drugs in relation to indicators of acid-base state impairment and renal function.
 Materials and methods. Ethylene glycol (EG) was administered per os to Wistar male rats (190210 g b.w.) at a single dose of 6 mL/kg b.w. through an atraumatic gastric tube. The animals were divided into 4 groups of 6 individuals each: intact (negative control), EG poisoning (positive control), EG + standard antidote therapy, EG + dimephosphon therapy. Experimental therapy was carried out for first 24 hours using standard antidote therapy: ethanol (30% solution 2 mL/kg b.w. i.p. after 1, 4, 6, 12, 18 hours) and sodium bicarbonate (4 % solution 6 mL/kg b.w. i.p. 3 times on the first day), as well as administration of dimephosphon (150 mg/kg i.p. 3 times on the first day, 450 mg/kg b.w. per day). Daily urine on day 3 after poisoning was collected in metabolic cages. Creatinine concentration in urine and blood serum samples were measured, and creatinine clearance was calculated. After 24 hours of therapy, the pH, level of sodium, potassium, calcium, magnesium, chlorides, bicarbonates, lactate, D-3-hydroxybutyrate, albumin, urea and creatinine (measured parameters) were determined in venous blood samples. Anion gap, ∆рН, ∆AG, ∆HCO3, ∆AG/∆HCO3 and ∆Gap were calculated. The mechanism of death was determined for the dead animals. Data processing was performed using GraphPad Prism 6.0.
 Results. Acute poisoning of rats with ethylene glycol leads to the development of toxic encephalopathy and nephropathy, acid-base abnormalities, high anion gap metabolic acidosis due to the presence of metabolites, as well as lactate-ketoacidosis due to depression of the central nervous system. 100% of the EG-treated (12 mL/kg b.w.) animals died within 3 days. Metabolic acidosis in combination with hypermagnesemia had provided a cardiodepressive effect, which with direct nephrotoxic and neurotoxic effects contributed to the development of a mixed variant of thanatogenesis and death. Death comes from toxic encephalopathy and nephropathy, high anion gap metabolic acidosis caused by direct nephrotoxic and neurotoxic effects of EG and its metabolites. The standard antidote therapy with ethanol in combination with sodium bicarbonate prevented a pH shift, lactic acidosis and ketoacidosis, an increase in urea, but did not affect the level of bicarbonate (p = 0,048), creatinine and its clearance (p = 0,037) and the anion gap (p = 0,033). The dimephosphon therapy prevented a decrease in creatinine clearance and blood bicarbonate level, limited the increase in lactate dehydrogenase activity, had a more pronounced effect on the AG and ∆AG (p = 0,042), but did not affect the hypocalcemia (p = 0,0076) and hypoalbuminemia (p = 0,021).
 Conclusion. Acute ethylene glycol poisoning leads to the development of a mixed variant of thanatogenesis with damage to the central nervous and urinary systems, as well as the heart. Autopsy and histopathology confirmed the cause of animal death. In the model at a dose of 6 mL/kg of EG the dimephosphon therapy was more conducive to the correction of the main markers of high anion gap metabolic acidosis (HAGMA) than standard antidote therapy (both measured and calculated, p 0,05). The dimephosphon therapy prevented a decrease in creatinine clearance. A comparative analysis of two methods for the correction of high anion gap metabolic acidosis in rats in acute poisoning with ethylene glycol showed that dimephosphon therapy vs. standard antidote therapy had a stronger effect on markers of metabolic acidosis and renal impairment.

Interplay of microRNA‐503 and N‐acetylcysteine in regulating hypoxia‐reoxygenation injury in cardiomyocyte H9C2 cells

microRNAs(miRs) are involved in many cardiovascular diseases including myocardial ischemia / reperfusion injury (IRI). Myocardial IRI can lead to oxidative stress, many miRs are regulated in response to oxidative stress. N‐acetylcysteine (NAC) –a known antioxidant, is reported to have protective effects against myocardial IRI. Previously, we and others observed that cardiac miR‐503 was down‐regulated during myocardial IRI in vivo in rodents or in cardiomyocyte H9C2 cells subjected to hypoxia and reoxygenation (H/R). This study is aimed to explore the interplay of miR503 and NAC in the regulation of hypoxia‐reoxygenation injury and possible molecular mechanisms in cardiomyocyte H9C2 cells. Here, H9C2 cells were subjected to hypoxia for 10 hours followed by reoxygenation 6 hours as simulated myocardial IRI. Results showed that cell viability was decreased and lactate dehydrogenase (LDH) activity was increased upon H/R; Pretreatment with NAC (1mM) to H9C2 cells for 30 hours can improve cell viability and reduce LDH activity in both normoxia and H/R states, while pretreatment with NAC (2mM) decreased cell viability and increased LDH activity. We also found that NAC (1mM) can down‐regulate miR‐503 expression level in H9C2 cells subjected to normoxia, it also down‐regulated miR‐503 expression level upon H/R. In order to inhibit endogenous miR‐503, H9C2 cells was transfected with Antagomir‐503, inhibition of miR‐503 can improve cell viability and reduce LDH activity upon H/R; Western blotting results showed that there was no significant difference among control, HR, HR+negative control of Antagomir‐503(NC) or HR+Antagomir‐503 groups for proapoptotic Bax protein, while anti‐apoptotic Bcl2 protein was increased after transfection of Antagomir‐503 compared with HR+NC. Target‐Scan software showed that Phosphoinositide‐3‐kinase, regulatory subunit 1(PI3K p85) is one of miR‐503 target genes, and P85 protein was decreased after H/R, but it was increased significantly after administration of Antagomir‐503, its down‐stream protein phospho‐AKT (Thr450) was also significantly increased. However, Antagomir‐503 and NAC (1mM) used in combination to H9C2 cells upon H/R, did not provide an additional advantage in protecting cell injury. It is concluded that administration of NAC (1mM) or Antagomir‐503 alone can alleviate cell injury, while the combination of NAC (1mM) and Antagomir‐503 has no synergistic cytoprotective effects, the possible molecular mechanisms need to be further explored.Support or Funding InformationSupported by Hong Kong RGC(17158616 M) and HMRF (05161826)grants.

MiR-328 inhibits cell apoptosis and improves cardiac function in rats with myocardial ischemia-reperfusion injury through MEK-ERK signaling pathway.

To explore the influences of micro ribonucleic acid (miR)-328 on rats with myocardial ischemia-reperfusion (IR) injury through the methyl ethyl ketone (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway. A total of 36 Sprague-Dawley rats were randomly assigned into the sham group (n=12), model group (n=12), and miR-328 group (n=12). The model of myocardial IR injury was established by ligating the left anterior descending coronary artery, without any intervention in the model group, while 200 μL of miR-328 antagomir was intravenously injected before modeling in the miR-328 group. The activity of the serum myocardial enzymes lactate dehydrogenase (LDH) and creatine kinase-muscle/brain (CK-MB) was determined via ELISA to assess the cardiac function in the three groups of rats, and the mRNA expression level of miR-328 in myocardial tissues was measured through real-time fluorescence qRT-PCR in the sham group, model group, and miR-328 group. TUNEL staining was performed to detect apoptotic cells, and the levels of myocardial apoptosis-associated protein Caspase-3 and phosphorylated MEK1/2 (p-MEK1/2) and p-ERK1/2 proteins were determined using Western blotting. Compared with the sham group, the model group exhibited increased activity of LDH and CK-MB, miR-328 expression level, apoptotic cells, the relative expression level of Caspase-3, and protein levels of p-MEK and p-ERK, with statistically significant differences (p<0.05). Besides, in comparison with the model group, miR-328 group showed a decreased activity of LDH and CK-MB, miR-328 expression level, the relative expression level of Caspase-3, and protein levels of p-MEK and p-ERK, displaying statistically significant differences (p<0.05). MiR-328 modulates the MEK-ERK signaling pathway to inhibit cell apoptosis and improve the cardiac function in rats with myocardial IR injury.

Metabolome Analysis Reveals Excessive Glycolysis via PI3K/AKT/mTOR and RAS/MAPK Signaling in Methotrexate-Resistant Primary CNS Lymphoma-Derived Cells.

Metabolome analysis is an emerging method that provides insight into intracellular and physiologic responses. Methotrexate (MTX) is an antifolate that suppresses DNA syntheses by inhibiting dihydrofolate reductase. High-dose methotrexate treatment with deferred radiotherapy is a standard protocol in primary central nervous system lymphoma (PCNSL) treatments. However, most cases come to relapse-acquired resistance, in which the role of metabolic pathways is largely unknown. Metabolome analysis in methotrexate-resistant PCNSL-derived cells (designated as TK-MTX and HKBML-MTX) was performed to detect alternative metabolites and pathways. The metabolomic analyses using capillary electrophoresis-time-of-flight mass spectrometry detected 188 and 169 peaks in TK- and HKBML-derived cells, respectively, including suppression of central carbon metabolism, lipid metabolism, nucleic acid metabolism, urea cycle, branched chain and aromatic amino acids, and coenzyme metabolism. Particularly, whole suppressive metabolic pathways were demonstrated in TK-MTX, whereas HKBML-MTX indicated partially enhanced pathways of the urea cycle, amino acid metabolism, and coenzyme metabolism. Reciprocally detected metabolites for glycolysis, including induced glucose and reduced glycogen, and induced lactate and reduced pyruvate, in addition to increased lactate dehydrogenase activity, which is involved in Warburg effect. Thereby, ATP was increased in both methotrexate-resistant PCNSL-derived cells. Furthermore, we specifically found that PI3K/AKT/mTOR and RAS/MAPK signaling pathways were activated in TK-MTX but not in HKBML-MTX by growth rate with inhibitors and gene expression analysis, suggestive of cell type-specific methotrexate-resistant metabolic pathways. These results can help us understand targeted therapies with selective anticancer drugs in recurrent CNS lymphoma-acquired resistance against methotrexate.

Bifenthrin insecticide promotes oxidative stress and increases inflammatory mediators in human neuroblastoma cells through NF-kappaB pathway

The extensive application of bifenthrin (BF) insecticide in agriculture has raised serious concerns with regard to increased risks of developing neurodegenerative diseases. Recently, our group showed that BF exposure in rodent models induced oxidative stress and inflammation markers in various regions of the brain (frontal cortex, striatum and hippocampus) and this was associated with behavioral changes. This study aimed to confirm such inflammatory and oxidative stress in an in vitro cell culture model of SK-N-SH human neuroblastoma cells. Markers of oxidative stress (ROS, NO, MDA, H2O2), antioxidant enzyme activities (CAT, GPx, SOD) and inflammatory response (TNF-α, IL-6, PGE2) were analyzed in SK-N-SH cells after 24 h of exposure to different concentrations of BF (1–20 μM). Protein synthesis and mRNA expression of the enzymes implicated in the synthesis of PGE2 were also measured (COX-2, mPGES-1) as well as nuclear factor κappaB (NF-κBp65) and antioxidant nuclear erythroid-2 like factor-2 (Nrf-2). Cell viability was analyzed by MTT-tetrazolio (MTT) and lactate dehydrogenase (LDH) assays. Exposure of SK-N-SH cells to BF resulted in a concentration-dependent reduction in the number of viable cells (reduction of MTT and increase in LDH activity). There was also a BF concentration-dependent increase in oxidative stress markers (ROS release, NO, MDA and H2O2) and decrease in the activity of antioxidant enzymes (CAT and GPx activities). There was further a concentration-dependent increase in pro-inflammatory cytokines (TNF-α and IL-6) and inflammatory mediator PGE2, increase in protein synthesis and mRNA expression of inflammatory markers (COX-2, mPGES-1 and NF-κBp65) and decrease in protein synthesis and mRNA expression of antioxidant Nrf-2. Our data shows that BF induces various oxidative stress and inflammatory markers in SK-N-SH human neuroblastoma cells as well as the activation of NF-κBp65 signaling pathway. This is in line with prior results in brain regions of rodents exposed in vivo to BF showing increased oxidative stress in response to BF exposure, occurring in pro-inflammatory conditions and likely activating programmed cell death.

Влияние гепарина и этанола на активность лактатдегидрогеназы в митохондриальной и цитоплазматической фракциях клеток печени крыс

Experiments on rats have shown that ethanol at a dose of 4.5 g/kg leads to an increase in the activity of lactate dehydrogenase (LDH) in rat liver cells in a direct reaction in subcellular fractions. In the cytoplasmic fraction, the LDH activity in the reverse reaction decreased. Pre-administration of heparin to animals at a dose of 250 IU/kg partially neutralizes the effects of intraperitoneal administration of ethanol, which is expressed in a decrease in the activity of LDH in rat liver cells in a direct reaction in subcellular fractions. Binding of endogenous heparin to protamine sulfate and subsequent administration of ethanol leads to an increase in LDH activity in the mitochondrial fraction of rat liver cells.

Metabolic Adaptation of Airway Smooth Muscle Cells to an SPHK2 Substrate Precedes Cytostasis.

Thickening of the airway smooth muscle is central to bronchial hyperreactivity. We have shown that the sphingosine analog (R)-2-amino-4-(4-heptyloxyphenyl)-2-methylbutanol (AAL-R) can reverse preestablished airway hyperreactivity in a chronic asthma model. Because sphingosine analogs can be metabolized by SPHK2 (sphingosine kinase 2), we investigated whether this enzyme was required for AAL-R to perturb mechanisms sustaining airway smooth muscle cell proliferation. We found that AAL-R pretreatment reduced the capacity of live airway smooth muscle cells to use oxygen for oxidative phosphorylation and increased lactate dehydrogenase activity. We also determined that SPHK2 was upregulated in airway smooth muscle cells bearing the proliferation marker Ki67 relative to their Ki67-negative counterpart. Comparing different stromal cell subsets of the lung, we found that high SPHK2 concentrations were associated with the ability of AAL-R to inhibit metabolic activity assessed by conversion of the tetrazolium dye MTT. Knockdown or pharmacological inhibition of SPHK2 reversed the effect of AAL-R on MTT conversion, indicating the essential role for this kinase in the metabolic perturbations induced by sphingosine analogs. Our results support the hypothesis that increased SPHK2 levels in proliferating airway smooth muscle cells could be exploited to counteract airway smooth muscle thickening with synthetic substrates.

The silent information regulator 1 pathway attenuates ROS-induced oxidative stress in Alzheimer's disease

We show that down-regulation of circular ribonucleic acid 0001588 with small interfering-circular ribonucleic acid 0001588 mimics promoted caspase-3 and caspase-9 activity levels, increased lactate dehydrogenase activity levels, and reduced cell growth of in vitro model. Circular ribonucleic acid 0001588 plasmids increased circular ribonucleic acid 0001588 expressions and promoted cell growth and reduced activity levels of lactate dehydrogenase, caspase-3, and caspase-9 activity levels in vitro model of Alzheimer's disease. Then, circular ribonucleic acid 0001588 down-regulation also promoted reactive oxygen species production and oxidative stress (malonaldehyde), and reduced superoxide dismutase, glutathione, and glutathione peroxidase levels by suppressing of silent information regulator 1/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 in vitro. However, over-expression of circular ribonucleic acid 0001588 reduced reactive oxygen species production and malonaldehyde levels and increased superoxide dismutase, glutathione, and levels via activation signal pathway of silent information regulator 1/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway by miR-211-5p up-regulation in vitro. Over-expression of miR-211-5p attenuated the role of circular ribonucleic acid 0001588 on Alzheimer's disease-induced oxidative stress. Also, activation of the silent information regulator 1 pathway attenuated the antioxidative effects of circular ribonucleic acid 0001588 down-regulation on oxidative stress by activating silent information regulator 1/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 in vitro. In conclusion, our findings indicated that circular ribonucleic acid 0001588 induced the silent information regulator 1/nuclear factor erythroid 2-related factor 2-dependent heme oxygenase-1 pathway to prevent oxidative stress by miR-211-5p in the rat model or in vitro model of a sporadic type of Alzheimer's disease. Therefore, the expression of the circular ribonucleic acid 0001588 gene was inhibited in rodent Alzheimer's disease model.

Propylene Glycol Caprylate as a Novel Potential Absorption Enhancer for Improving the Intestinal Absorption of Insulin: Efficacy, Safety, and Absorption-Enhancing Mechanisms

Sodium caprate (C10) acts as an absorption enhancer. However, the absorption-enhancing effects of compounds with structures similar to C10 have not been characterized. In the present study, insulin was used as a model drug. We examined the effects of C10 and its related compounds on intestinal absorption of insulin using an in situ closed loop in rats. Insulin absorption was significantly enhanced by propylene glycol caprylate (Sefsol-218), a C10-related compound, after large intestinal administration. In addition, activity of lactate dehydrogenase did not increase in the intestinal epithelium in the presence of Sefsol-218 at concentrations equivalent to or lower than 1% (v/v). However, a significant increase in lactate dehydrogenase activity was observed in response to C10. These findings suggested that Sefsol-218 was safer than C10. Furthermore, mechanistic studies showed that increased membrane fluidity and loosening of tight junctions (TJs) might be underlying mechanisms by which this compound improved intestinal absorption of insulin. Furthermore, Sefsol-218 opened TJs by reducing the expression of claudin-4, which is a major TJ protein. These findings suggested that Sefsol-218 effectively enhanced intestinal insulin absorption without causing serious damage to the intestinal epithelium.

Seabream Larval Physiology under Ocean Warming and Acidification

The vulnerability of early fish stages represents a critical bottleneck for fish recruitment; therefore, it is essential to understand how climate change affects their physiology for more sustainable management of fisheries. Here, we investigated the effects of warming (OW; +4 °C) and acidification (OA; ΔpH = 0.5) on the heart and oxygen consumption rates, metabolic enzymatic machinery—namely citrate synthase (CS), lactate dehydrogenase (LDH), and ß-hydroxyacyl CoA dehydrogenase (HOAD), of seabream (Sparus aurata) larvae (fifteen days after hatch). Oxygen consumption and heart rates showed a significant increase with rising temperature, but decreased with pCO2. Results revealed a significant increase of LDH activity with OW and a significant decrease of the aerobic potential (CS and HOAD activity) of larvae with OA. In contrast, under OA, the activity levels of the enzyme LDH and the LDH:CS ratio indicated an enhancement of anaerobic pathways. Although such a short-term metabolic strategy may eventually sustain the basic costs of maintenance, it might not be adequate under the future chronic ocean conditions. Given that the potential for adaptation to new forthcoming conditions is yet experimentally unaccounted for this species, future research is essential to accurately predict the physiological performance of this commercially important species under future ocean conditions.

Evaluation of changes in the carbohydrate metabolism of Biomphalaria glabrata Say, 1818 exposed to experimental coinfection by Angiostrongylus cantonensis (Nematoda) and Echinostoma paraensei (Trematoda)

The interaction between intermediate snail hosts and helminths can cause metabolic changes in the former. The snails use their reserves for maintenance of their vital processes, by activating the internal defense system and repairing tissue damage, while also supplying necessary energy for the parasites’ development. Our aims were to evaluate the lactate dehydrogenase activity and the glucose concentration in the hemolymph of Biomphalaria glabrata experimentally coinfected by Angiostrongylus cantonensis and Echinostoma paraensei. Besides these aspects, the glycogen content in the digestive gland complex and cephalopedal mass along with histochemical changes in parasitized snails were analyzed. The snails were divided in group A (infected by 1200 L1 of A. cantonensis), group E (infected by 20 E. paraensei miracidia), group A + E (co-infected with A. cantonensis first and after a week by E. paraensei), group E + A (co-infected with E. paraensei first and then by A. cantonensis) and control group (not infected). During four weeks after exposure, samples were collected for biochemical and histochemical analyses. In the infected snails, glucose levels and glycogen content in the digestive gland complex and cephalopedal mass were significantly lower, in contrast with an increase of lactate dehydrogenase activity. These results indicate that the intense energy demand resulting from the presence of parasites causes the host snail to accelerate the anaerobic degradation of carbohydrates to obtain energy, in an attempt to maintain homeostasis. Both parasites were observed in histochemical analysis to cause tissue damages in the snails. So, although the snails were able to sustain the coinfection, several metabolic and tissue changes occurred, mainly in those infected with E. paraensei and then with A. cantonensis.

Underfilling of vacuum blood collection tubes leads to increased lactate dehydrogenase activity in serum and heparin plasma samples.

Background Lactate dehydrogenase (LD) activity is routinely monitored for therapeutic risk stratification of malignant diseases, but is also prone to preanalytical influences. Methods We systematically analyzed the impact of defined preanalytical conditions on the hemolysis-susceptible parameters LD, potassium (K) and hemolysis index in vacuum blood collection tubes (serum [SE], heparin plasma [HP]). Blood was collected by venipuncture from healthy volunteers. Tubes were either filled or underfilled to approximately 50%, then processed directly or stored at room temperature for 4 h. Potassium (K), sodium (Na), chloride (Cl), LD, creatine kinase (CK), total cholesterol, and indices for hemolysis, icterus, and lipemia were analyzed. Filling velocity was determined in a subset of tubes. Findings in healthy volunteers were reconfirmed in an in-patient cohort (n = 74,751) that was analyzed for plasma yield and LD data distribution. Results LD activity was higher in HP compared to SE. Underfilling led to higher LD values (SE: +21.6%; HP: +28.3%), K (SE: +4.2%; HP: +5.3%), and hemolysis index (SE: +260.8%; HP: +210.0%), while other analytes remained largely unchanged. Filling velocity of tubes was approximately 3-fold higher in the first half compared to the second half in both HP and SE collection tubes. Importantly, plasma yield also inversely correlated with LD in routine patients. By calculating reference limits, the lowest plasma yield quartile of the patient cohort displayed LD values clearly exceeding current reference recommendations. Conclusions Underfilling of tubes leads to a higher proportion of blood aspirated with high velocity and relevant elevations in LD. This finding should be considered in cases of clinically implausible elevated LD activities.

Metal nanoparticles-induced activation of NLRP3 inflammasome in human oral keratinocytes is a possible mechanism of oral lichenoid lesions

The NLRP3 inflammasome has been implicated in the pathogenesis of various inflammatory diseases and is activated by particulate stimulants. Oral epithelial keratinocytes are frequently exposed to metal nanoparticles. In this study, we examined the effects of gold, silver, and palladium nanoparticles, which are frequently used for dental metal alloys on cell proliferation, cytotoxicity, autophagy, lysosomal functions, and NLRP3 inflammasome activation using the immortalized human oral keratinocyte cell line RT-7. The metal nanoparticles were agglomerated in the membrane vesicles in RT-7 cells and suppressed cell proliferation and increased lactate dehydrogenase activity as well as the proportion of apoptotic cells. Silver and palladium nanoparticles induced autophagy and lysosomal dysfunctions and all metal nanoparticles tested triggered the secretion of IL-1β through caspase-1 activation. Furthermore, the epithelium obtained from patients with oral lichenoid lesions (OLLs) had robust NLRP3, ASC, caspase-1, and IL-1β-positive keratinocytes and cDNA microarray showed significant elevation in the mRNA levels of NLRP3. These results suggest that internalized metal nanoparticles in oral mucosal epithelial cells activate the NLRP3 inflammasome through the induction of lysosomal damage and autophagy dysfunction. This process may be involved in the pathogenesis of OLL and suggest its potential as an alternative target for OLL therapy.

Transcriptional profiling of zearalenone-induced inhibition of IPEC-J2 cell proliferation

Mounting evidence has shown that zearalenone (ZEA) can have toxic effects on the intestinal epithelial cells (IECs) of mammals and humans, but the mechanism of ZEA-induced toxicity on IECs is unclear. The aim of this study was to reveal the mechanism of action of ZEA on intestinal epithelial cells via RNA-seq technology. We measured the effects of ZEA on the viability and lactate dehydrogenase (LDH) activity of the pig intestinal epithelial cell line J2 (IPEC-J2). The results showed ZEA can decrease the IPEC-J2 cell viability and increase LDH activity. Appropriate treatment concentrations were determined (40 μM ZEA) to study the toxic effect of ZEA on IPEC-J2. The results showed that 40 μM ZEA significantly inhibited IPEC-J2 proliferation and arrested the cell cycle at the G2/M phase. A total of 783 differentially expressed genes (DEGs) were identified after ZEA treatment. KEGG pathway analysis revealed that PERK regulates gene expression, Toll-like receptor cascades signaling pathway, mitosis, mitotic metaphase and anaphase, DNA replication and G2/M checkpoints, were involved in the cell cycle pathway. Eleven key genes involved in G2/M checkpoints were validated by qPCR. Thus, these data highlighted that ZEA caused abnormalities in the G2/M transition in IPEC-J2 cells by altering the cell cycle signaling pathway, thereby inhibiting cell proliferation and inducing injury in IECs. And the study will contribute to get the molecular mechanisms of ZEA inhibition of IECs cell proliferation.

Bone mesenchymal stem cell-conditioned medium attenuates the effect of oxidative stress injury on NSCs by inhibiting the Notch1 signaling pathway.

Numerous studies have demonstrated the therapeutic effect of bone mesenchymal stem cells on spinal cord injury (SCI), especially on neural stem cells (NSCs). However, the predominant mechanisms of bone mesenchymal stem cells (BMSCs) are unclear. Recently, some researchers have found that paracrine signaling plays a key role in the therapeutic capacity of BMSCs and emphasized that the protective effect of BMSCs may be due to paracrine factors. In this study, we aimed to investigate the potential mechanisms of BMSCs to protect NSCs. NSCs were identified by immunocytochemistry. The oxidative stress environment was simulated by H2 O2 (50, 100, 200 μM) for 2 h. The apoptotic rate of the NSCs was detected via flow cytometry. Lactate dehydrogenase (LDH), malondialdehyde (MDA), and superoxide dismutase (SOD) activity were evaluated via corresponding assay kits. Western blot was used to detect the expressions of Notch1, HES1, caspase-3, cleave caspase-3, Bax, and Bcl-2. We found that H2 O2 could significantly induce the apoptosis of NSCs, increase LDH, MDA levels, and decrease SOD activity by activating the Notch1 signaling pathway. DAPT (the specific blocker of Notch1) and BMSC-conditioned medium (BMSC-CM) could significantly prevent the apoptotic effect and oxidative stress injury on NSCs that were treated with H2 O2 . We also revealed that BMSC-CM could decrease the expression of Notch1, Hes1, cleave caspase-3, Bax, and increases the expression of Bcl-2 in NSCs, which was induced by H2 O2 . These results have revealed that BMSC-CM can neutralize the effect against oxidative stress injury on the apoptosis of NSCs by inhibiting the Notch1 signaling pathway.

Effect of long-term thermal challenge on the Antarctic notothenioid Notothenia rossii.

The thermal stability of the Antarctic Ocean raises questions concerning the metabolic plasticity of Antarctic notothenioids to changes in the environmental temperature. In this study, Notothenia rossii survived 90days at 8°C, and their condition factor level was maintained. However, their hepatosomatic (0.29×) index decreased, indicating a decrease in nutrient storage as a result of changes in the energy demands to support survival. At 8°C, the plasma calcium, magnesium, cholesterol, and triglyceride concentrations decreased, whereas the glucose (1.91×) and albumin (1.26×) concentrations increased. The main energy substrate of the fish changed from lipids to glucose due to a marked increase in lactate dehydrogenase activity, as demonstrated by an increase in anaerobic metabolism. Moreover, malate dehydrogenase activity increased in all tissues, suggesting that fish acclimated at 8°C exhibit enhanced gluconeogenesis. The aerobic demand increased only in the liver due to an increase (2.23×) in citrate synthase activity. Decreases in the activities of superoxide dismutase, catalase, and glutathione-S-transferase to levels that are most likely sufficient at 8°C were observed, establishing a new physiological activity range for antioxidant defense. Our findings indicate that N. rossii has some compensatory mechanisms that enabled its long-term survival at 8°C.