Amount Of LDH Research Articles

Improvement of optical, dielectric and mechanical properties of a new nanocomposite based on polyvinyl alcohol and layered double hydroxide

In this work, films in the form of poly (vinyl alcohol)/Layered Double Hydroxide (PVA/LDH) nanocomposites were synthesized with different amount of LDH (0%; 4% and 6%), and characterized by X-ray diffraction (XRD), infrared spectroscopy scanning electron microscopy (SEM), impedance spectroscopy and UV-Vis-NIR spectroscopy. Different characterizations were used to investigate the electrical/dielectric, optical and mechanical properties of the nanocomposite films XRD and infrared spectroscopy results showed that clay particles exist in the polymer matrix. Electrical modeling was established using an equivalent electrical circuit consisting of two blocks, and confirmed by fitting the experimental conductivity data according to Jonscher’s double power law. Moreover, the reinforcement of the composite matrix by the addition of LDH particles, showed a shift of the relaxations towards the low frequencies, and led to an increase of dielectric constant, conductivity, and absorption of the light in the ultraviolet domain with a decrease of the gap energy. As for the mechanical properties, namely the Young’s modulus, is tripled when the clay content is about 6%.

Tanshinone IIA alleviates hypoxia/reoxygenation induced cardiomyocyte injury via lncRNA AK003290/miR-124-5p signaling

BackgroundAcute myocardial infarction (AMI) is the leading cause of death globally and has thus placed a heavy burden on healthcare. Tanshinone IIA (TSA) is a major active compound, extracted from Salvia miltiorrhiza Bunge, that possesses various pharmacological activities. The aim of the present study was to investigate the role of TSA in AMI and its underlying mechanism of action. Results: We have shown that TSA decreased the apoptosis rate, the amount of LDH, MDA as well as ROS of cardiomyocytes. Meantime, it elevated mitochondrial membrane potential (MMP) which was decreased by H/R treatment. It was also determined that miR-124-5p targets AK003290 directly. TSA up-regulated the expression of AK003290 and its function can be reversed by knock down of AK003290 as well as miR-124-5p overexpression.ConclusionTSA exerts the protective role against H/R induced apoptosis, oxidative and MMP loss of cardiomyocytes via regulating AK003290 and miR-124-5p signaling.

In Vitro Evaluation of the Neuroprotective Effect of Panax notoginseng Saponins by Activating the EGFR/PI3K/AKT Pathway.

Objective This study investigated whether Panax notoginseng saponins (PNS) extracted from Panax notoginseng (Bruk.) F. H. Chen played a neuroprotective role by affecting the EGFR/PI3K/AKT pathway in oxygen-glucose deprived (OGD) SH-SY5Y cells. Materials and Methods Different groups of OGD SH-SY5Y cells were treated with varying doses of PNS, PNS + AG1478 (a specific inhibitor of EGFR), or AG1478 for 16 hours. CCK8, Annexin V-FITC/PI apoptosis analysis, and LDH release analysis were used to determine cell viability, apoptosis rate, and amounts of LDH. Quantitative real-time PCR (q-RT-PCR) and western blotting were used to measure mRNA and proteins levels of p-EGFR/EGFR, p-PI3K/PI3K, and p-AKT/AKT in SH-SY5Y cells subjected to OGD. Results PNS significantly enhanced cell viability, reduced apoptosis, and weakened cytotoxicity by inhibiting the release of LDH. The mRNA expression profiles of EGFR, PI3K, and AKT showed no difference between model and other groups. Additionally, ratios of p-EGFR, p-PI3K, and p-AKT to EGFR, PI3K, and AKT proteins expression, respectively, all increased significantly. Conclusions These findings indicate that PNS enhanced neuroprotective effects by activating the EGFR/PI3K/AKT pathway and elevating phosphorylation levels in OGD SH-SY5Y cells.

Trichosanthis Pericarpium Aqueous Extract Protects H9c2 Cardiomyocytes from Hypoxia/Reoxygenation Injury by Regulating PI3K/Akt/NO Pathway

Trichosanthis Pericarpium (TP) is a traditional Chinese medicine for treating cardiovascular diseases. In this study, we investigated the effects of TP aqueous extract (TPAE) on hypoxia/reoxygenation (H/R) induced injury in H9c2 cardiomyocytes and explored the underlying mechanisms. H9c2 cells were cultured under the hypoxia condition induced by sodium hydrosulfite for 30 min and reoxygenated for 4 h. Cell viability was measured by MTT assay. The amounts of LDH, NO, eNOS, and iNOS were tested by ELISA kits. Apoptotic rate was detected by Annexin V-FITC/PI staining. QRT-PCR was performed to analyze the relative mRNA expression of Akt, Bcl-2, Bax, eNOS, and iNOS. Western blotting was used to detect the expression of key members in the PI3K/Akt pathway. Results showed that the pretreatment of TPAE remarkably enhanced cell viability and decreased apoptosis induced by H/R. Moreover, TPAE decreased the release of LDH and expression of iNOS. In addition, TPAE increased NO production and Bcl-2/Bax ratio. Furthermore, the mRNA and protein expression of p-Akt and eNOS were activated by TPAE pretreatment. On the contrary, a specific inhibitor of PI3K, LY294002 not only inhibited TPAE-induced p-Akt/eNOS upregulation but alleviated its anti-apoptotic effects. In conclusion, results indicated that TPAE protected against H/R injury in cardiomyocytes, which consequently activated the PI3K/Akt/NO signaling pathway.

Mechanism underlying docosahexaenoic acid-induced regulation of angiopoietin expression in human brain vascular pericytes subjected to oxygen-glucose deprivation and restoration: the relationship with SSeCKS

Objective To evaluate the relationship between the mechanism underlying docosahexaenoic acid (DHA)-induced regulation of angiopoietin expression and Src-suppressed C kinase substrate (SSeCKS) in human brain vascular pericytes (HBVPs) subjected to oxygen-glucose deprivation and restoration (OGD/R). Methods HBVPs were seeded in 96-well or in 6-well plates at a density of 2×105 cells/ml and divided into 5 groups (n=18 each) using a random number table: control group (group C), OGD/R group, DHA group (group D), SSeCKS gene silencing group (group S) and SSeCKS gene silencing plus DHA group (group SD). The model of OGD/R injury was established as follows: the cells were subjected to O2-glucose deprivation for 24 h in glucose- and serum-free culture medium aerated with 94%N2-5%CO2-1%O2 followed by restoration of O2-glucose supply for 6 h in high-glucose DMEM culture medium in normal atmosphere.DHA was added at 1 h before hypoxia with the final concentration of 40 μmol/L in group D. Small interfering RNA induced SSeCKS gene silencing in S and SD groups.Subsequently, DHA with the final concentration of 40 μmol/L was added at 1 h before hypoxia in group SD.At 6 h of reoxygenation, the cell survival rate was determined by CCK-8 assay, the amount of LDH released was detected using ELISA, and the expression of SSeCKS, angiopoietin-1 (Ang-1) and Ang-2 was detected by Western blot. Results Compared with group C, the cell survival rate was significantly decreased, the amount of LDH released was increased, the expression of SSeCKS and Ang-1 was down-regulated, the expression of Ang-2 was up-regulated, and Ang-1/Ang-2 ratio was decreased in group OGD/R, and the expression of SSeCKS was down-regulated in group S (P 0.05). Compared with group D, the cell survival rate was significantly decreased, the amount of LDH released was increased, the expression of SSeCKS and Ang-1 was down-regulated, the expression of Ang-2 was up-regulated, and Ang-1/Ang-2 ratio was decreased in group SD (P<0.05). Conclusion The mechanism by which DHA increases the ratio of Ang-1/Ang-2 may be totally related to up-regulation of SSeCKS expression in HBVPs subjected to OGD/R. Key words: Docosahexaenoic acids; A kinase anchor proteins; Angiopoietins; Pericytes; Brain; Reperfusion injury

Biological evaluation of 2-hydroxyethylmethacrylate (HEMA) toxicity in human gingival fibroblasts with histochemical X-ray microanalysis.

To analyze the cytotoxic effects of 2-hydroxyethylmethacrylate (HEMA) in human gingival fibroblasts using quantitative x-ray microanalysis (EXPMA) and two classical methods (DNA and LDH release in culture medium). Different concentrations of HEMA (5, 10, 20, 30, and 40 mM) in DMEM medium were used and the effects on human gingival fibroblasts after 6, 12, and 24 h were determined. As controls, fibroblasts cultured with DMEM culture medium (negative control) and fibroblast incubated in 1% triton X (positive control) were used. The results showed that correlation between the concentrations of HEMA and the amount of LDH and DNA released to the medium were statistically significant for all times analyzed. LDH and DNA released from cells incubated in the lowest concentrations of HEMA (5 and 10 mM) were not significantly different to negative controls. In contrast, cells incubated in the highest HEMA concentrations (20, 30, 40 mM) showed a significant increase of both LDH and DNA released to the culture medium at 6, 12, and 24 h. On the other hand, the ionic concentration of the different elements analyzed in this work revealed that the contents of P, S, Cl, and K were significantly higher in the controls than in samples incubated for 6 h in 5 mM or 10 mM HEMA (p < 0.01). K/ Na index (an excellent marker of cell viability) showed a significant decrease, and therefore, viability was significantly reduced. The results suggest that EXPMA is a sensitive method that is able to detect early cell damage even before the cell membrane is altered.

Inhibitory Effect of PPARγ Agonist on the Proliferation of Human Pterygium Fibroblasts

Summary: The effects of DK2, a peroxisome proliferator-activated receptor γ agonist, on cultured human pterygium fibroblasts (HPFs) in virto were studied. The HPFs were incubated with 0–200 μmol/L DK2 for 12–72 h. The MTT method was used to assay the bio-activity of DK2 at different doses and time. The cytotoxic effect of DK2 was measured by LDH release assay. The cell cycle distribution and apoptosis were flow cytometrically detected. The expression of proliferating cell nuclear antigen (PCNA) in each group was detected by real-time PCR (RT-PCR) and Western blotting. The results showed that administration of 1–75 μmol/L DK2 for 12–72 h could significantly inhibit HPF proliferation in a dose- and time-dependent manner. DK2-treated cells did not release significant amount of LDH as compared with rosiglitazone-treated cells. After treatment with DK2 at concentrations of 15, 25 μmol/L for 24 h, the number of HPFs in G0/G1 phase was significantly increased while that in S phase was significantly decreased (P<0.05), leading to arrest at G0/G1 phase. The apoptosis rates of HPF cells in drug-treated groups were significantly higher than the rate of control group (P<0.05). At the dosage range between 15–25 μmol/L, DK2 could inhibit the expression of PCNA mRNA and protein in HPFs in a dose-dependent fashion (P<0.05). It was concluded that PPARγ agonist can significantly inhibit HPF proliferation, resulting in the arrest at G0/G1 phase, induce the apoptosis of HPFs, and suppress the synthesis of PCNA, in dose- and time-dependent manners.

Inorganic layered double hydroxides as ascorbic acid (vitamin C) delivery system—Intercalation and their controlled release properties

ZnFe– and MgFe–LDHs were prepared by the anion exchange method, with the aim of adsorption of the ascorbic acid from the aqueous solutions by ion exchange process between anionic derivatives in LDH (Cl) and the anionic vitamin. This leads to successful intercalation of the vitamin into gallery space of LDH that offers a new route to safe preservation of bioactivity as well as controlled release. The prepared LDHs were characterized by XRD, TG–DTA and FT-IR spectroscopy. Adsorption of the ascorbic acid by the LDH under investigation was studied in terms of pH value, amount of LDH, contact time, VC (ascorbate) concentration and chemical composition of the host materials. The results indicate the relatively fast adsorption of the anionic vitamin by ZnFe–LDH–Cl and MgFe–Cl–LDH; reaches the equilibrium in 60 min. The shapes of the adsorption isotherms suggest specific interaction and high affinity. The batch kinetics of ascorbic acid adsorption onto ZnFe–Cl and MgFe–Cl–LDHs were studied. Furthermore, their release behaviors are also examined by spontaneous deintercalation with carbonate anion.

A radiotracer probe to study metal interaction with human lactate dehydrogenase isoenzymes.

The electrophilic Ag+ ion was found to destroy completely the enzymatic activity of lactate dehydrogenase isoenzyme LDH-1 while other transition metal ions reduced its activity in varying degrees. A radiotracer probe involving 110mAg-labeled silver ion was used to understand the mechanism of denaturation of LDH and also to determine the number of active sites, if any, for substrate binding with the enzyme. Purified LDH-l was reacted with 110mAg-labeled silver ion and the mixture was passed through the sephadex G-75-120 gel to separate the 110mAg-LDH complex that might be formed during the reaction. The resulting elution curve revealed that a stable complex was formed. From the total radioactivity of 110mAg bound LDH, the specific activity of labeled Ag+ and the amount of LDH used the ratio of the number of moles of Ag+ reacted with 1 mol of LDH was computed. This was found to be approximately 4.0, indicating that there are four binding sites in LDD, probably one on each subunit. Kinetic studies of LDH catalysis of L-P reaction in the presence and absence of Ag+ ion suggest that silver ion is involved in competitive inhibition and that the interaction conforms to the "lock-and-key" model. The inhibition of catalysis by other metals is presumably of a noncompetitive type.

Iodination of lactate dehydrogenase isoenzymes using radioactive and inactive iodine

The iodination of lactate dehydrogenase isoenzymes which has not been attempted so far has been performed using radioactive and inactive iodine. A new method for the determination of trace amounts of protein-bound iodine in the range of 10–100 μg has been developed. Out of two methods employed for iodination, chloramine-T method was found to be superior to the lactoperoxidase method for iodination with both radioactive and inactive iodine. It was found that the amount of iodinated LDH formed during iodination depends on the amount of LDH and of the reagents used for iodination. Completely purified LHD-1 and LDH-2 isoenzymes were iodinated using both inactive and radioactive iodine. The iodinated isoenzymes were separated from the unreacted iodide by gel permeation chromatography using Sephadex G-75-120 column. The ratio of radioiodinated LDH to unreacted125I was largest (3.72) when the amount of LDH used was 4.54 μg. The specific activity obtained when iodination was carried out under optimum conditions was 238 μCi/μg. No radiation damage for the radioiodinated LDH was observed when it is kept for as long as two weeks after iodination.

Effect of cryogenic preservation (−80 °C) on polymorphonuclear neutrophil integrity as determined by biochemical analysis

The effect of cryopreservation on plasma membrane and granule associated enzymes of polymorphonuclear neutrophils (PMNs) was studied. The activity of PMNs to generate superoxide anions during phagocytosis was very sensitive to cryopreservation and exhibited approximately 60% inhibition in 24 hr. The total enzyme activity was not as affected during 1-month cryopreservation as that observed with the extracellular release of enzymes. Acid p-nitrophenyl phosphatase and peroxidase were released slightly from frozen and thawed PMNs. However, the extracellular release of LDH, a cytosol marker, and β-glucuronidase and lysozyme, granuleassociated enzymes, increased with cryopreservation time. The degree of release of these enzymes was LDH > β-glucuronidase > lysozyme. A considerable amount of LDH was extracellularly released after 1-month storage. Frozen and thawed PMNs became sensitive to hypotonic solutions, although fresh, nonfrozen PMNs were very resistant to hypotonic lysis. The hypotonic fragility increased even after 1 hr of cryopreservation. Addition of ATP to the preservation medium did not improve enzyme activity, enzyme release, or stimulated superoxide anion generation but increased the hypotonic fragility of PMNs. However, albumin showed protective effects against cryopreservation injury to the O 2 −-generating system, the extracellular enzyme release, and osmotic fragility.

Lactic dehydrogenase isoenzymes in arthritic synovial fluid: effect of cortisol.

SummarySynovial fluid in rheumatoid arthritis has been shown to contain very high amounts of LDH, especially LDH 5. The enzymes very probably derive from metabolically active synovial cells. Intra-articular cortisol treatment causes a marked decrease in the synovial fluid LDH.In osteoarthritis the synovial fluid LDH content is low and tends to increase following cortisol. The isoenzyme pattern of the effusions in 5 mesothelioma cases has been found to be similar to that of rheumatoid arthritic synovial fluid. The similarity between these two diseases with respect to hyaluronic acid changes and exudative tendency is also pointed out.