Barium alginate as a skeleton coating graphene oxide and bentonite-derived composites: Excellent adsorbent based on predictive design for the enhanced adsorption of methylene blue.

The phenomenon that calcium alginate does not exhibit high adsorption capacity as a carrier material has not been reasonably explained or solved. In this paper, a new viewpoint that the orbital energy level of metal ions and the binding degree of the α-l-guluronate and ß-d-mannuronate units affect the adsorption performance of the composite was innovatively proposed. Taking barium alginate (BA) as an example, the possibility of replacing calcium alginate is discussed. Barium alginate/graphene oxide (BA/GO) membranes and three-dimensional (3D) barium alginate-bentonite-graphene oxide derived (3D-BA) hydrogels were prepared by vacuum freeze-drying to remove methylene blue. The structure and morphology of the prepared adsorbents were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry and Fourier transform infrared spectroscopy. The effects of adsorbent dosage, doping ratio, temperature, contact time, pH value and initial dye concentration on the adsorption performance of BA composites were investigated. The adsorption capacities of the BA/GO and 3D-BA materials were 1011.3 and 710.3 mg/g, respectively. The BA/GO membrane exhibited stable filtration performance against high concentrations of dyes. Benefiting from the strong interaction between bentonite, sodium alginate and Ba2+, the 3D-BA hydrogel showed higher thermal stability and better adsorption efficiency than other materials. The Elovich kinetic model and Sips equation can appropriately describe the adsorption process. The results show that barium alginate is a better carrier material than calcium alginate.

Effect of Ghrelin Intervention on the Ras/ERK Pathway in the Regulation of Heart Failure by PTEN.

OBJECTIVE: To study the possible mechanism of ghrelin in heart failure and how it works. METHOD: In vitro results demonstrated that ghrelin alleviates cardiac function and reduces myocardial fibrosis in rats with heart failure. Moreover, ghrelin intervention increased PTEN expression level and reduced ERK, c-jun, and c-Fos expression level; in vivo experiments demonstrated that ghrelin intervention reduces mast memory expression and increases cardiomyocyte surface area, PTEN expression level, ERK, c-jun, c-Fos expression level, and cell surface area, while ERK blockade suppresses mast gene expression and reduces cell surface area. RESULTS: In vitro experimental results prove that we have successfully constructed a rat model related to heart failure, and ghrelin can alleviate the heart function of heart failure rats and reduce myocardial fibrosis. In addition, ghrelin is closely related to the decrease of the expression levels of ERK, c-jun, and c-Fos, but it can also increase the expression of PTEN in the rat model; in vivo experiments proved that we successfully constructed an in vitro cardiac hypertrophy model, and the intervention of ghrelin would reduce the expression of hypertrophic memory and increase the surface area of cardiomyocytes, increase the expression level of PTEN, and reduce the expression levels of ERK, c-jun, and c-Fos, while the blockade of PTEN will increase the expression of hypertrophy genes and increase the cell surface area, while the blockade of ERK will increase the expression of hypertrophic genes, which in turn will make the cell surface area reducing. CONCLUSION: Ghrelin inhibits the phosphorylation and nuclear entry of ERK by activating PTEN, thereby controlling the transcription of hypertrophic genes, improving myocardial hypertrophy, and enhancing cardiac function.

Adsorption of methylene blue by Nicandra physaloides(L.) Gaertn seed gum/graphene oxide aerogel.

In this study, a novel composite aerogel of Nicandra physaloides(L.) Gaertn seed, gum/graphene oxide (NPG/GO), was prepared by using a vacuum freeze drying method for methylene blue (MB) adsorption. The techniques, including Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), were adopted for studying the structure and surface characteristics of NPG/GO, with thermogravimetric analysis (TGA) being adopted for testing thermal properties. The effects of pH value, initial dye concentration, temperature and adsorbent dosage on adsorption performance were elaborately analysed. The adsorption kinetic studies showed that the process of adsorption follows Langmuir isotherm and a pseudo-second-order kinetic model. When the mass ratio of NPG to GO was 1.25:1, the adsorption capacity was the highest. According to Langmuir isotherm, the maximum adsorption capacity of 408.16 mg/g was higher than that of NPG. The specific surface area and average pore diameter of NPG/GO was measured as 2.70 m2/g and 4.8 nm, respectively. Thermodynamic analysis revealed that the adsorption process of methylene blue on NPG/GO was a spontaneous and endothermic process. In general, the prepared nanocomposites were excellent candidates for adsorption and removal process because of simple synthesis, low cost, high efficiency, non-toxicity, environment protection and degradability.

Adsorption of tetracycline by Nicandra physaloides (L.) Gaertn seed gum and Nicandra physaloides(L.) Gaertn seed gum/Carboxymethyl chitosan aerogel.

In this study, novel aerogels of Nicandra physaloides (L.) Gaertn seed gum (NPG) and Nicandra physaloides (L.) Gaertn seed gum/Carboxymethyl chitosan (NPG/CMC) were prepared by freeze-drying method for removing tetracycline (TC) from water. Scanning electron microscope (SEM), X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) were used to characterize structure and morphology of NPG and NPG/CMC aerogels. The average pore diameter of NPG and NPG/CMC were 3.04 and 1.2 nm, the specific surface areas were 2.67 and 0.73 m2/g, respectively. The maximum adsorption capacity of NPG and NPG/CMC aerogels for TC based on Langmuir isotherm was 266.7 and 332.23 mg/g respectively. Through thermodynamic and kinetic studies, it was found that the adsorption processes of the two adsorbents were spontaneous and followed the pseudo-second-order kinetic model. And the process of NPG adsorption of TC was endothermic, while NPG/CMC was exothermic.

Study on the Adsorption Performance of Casein/Graphene Oxide Aerogel for Methylene Blue.

Casein (CS) and graphene oxide (GO) were employed for the fabrication of a casein/graphene oxide (CS/GO) aerogel by vacuum freeze drying. Fourier transform infrared spectroscopy, scanning electron microscopy, surface area and micropore analysis (BET), and thermogravimetric analysis were used to characterize the specific surface area, structure, thermal stability, and morphology of the CS/GO aerogel. The influence of experimental parameters such as the GO mass fraction in the aerogel, metering of the adsorbent, pH, contact time, and temperature on the adsorption capacity of the CS/GO aerogel on methylene blue (MB) was also investigated. According to Langmuir isotherm determination, the maximum removal rate of MB from the CS/GO aerogel was 437.29 mg/g when the temperature was 293 K and pH was 8. Through kinetic and thermodynamic studies, it is found that adsorption follows a pseudo-second-order reaction model and is also an exothermic and spontaneous process.

Hydroxychloroquine/Chloroquine as Therapeutics for COVID-19: Truth under the Mystery.

The outbreak of coronavirus disease-19 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly evolved into a global pandemic. One major challenge in the battle against this deadly disease is to find effective therapy. Due to the availability and proven clinical record of hydroxychloroquine (HCQ) and chloroquine (CQ) in various human diseases, there have been enormous efforts in repurposing these two drugs as therapeutics for COVID-19. To date, substantial amount of work at cellular, animal models and clinical trials have been performed to verify their therapeutic potential against COVID-19. However, neither lab-based studies nor clinical trials have provided consistent and convincing evidence to support the therapeutic value of HCQ/CQ in the treatment of COVID-19. In this mini review we provide a systematic summary on this important topic and aim to reveal some truth covered by the mystery regarding the therapeutic value of HCQ/CQ in COVID-19.

One-step generation of S and N co-doped reduced graphene oxide for high-efficiency adsorption towards methylene blue.

S and N co-doped reduced graphene (S-N-rGO) nanohybrids were prepared by a one-step oil bath heating process using glutathione (GSH) as a green and mild co-reduction agent and a S and N source. It can be applied in the field of adsorption for the removal of methylene blue (MB) from aqueous solutions. The efficient adsorption rate of S-N-rGO hybrids for MB (50 mg L-1) was observed with the best even within 2'07'' from blue solutions into colorless (the mass ratio GO : GSH = 60 : 200). Under this mass ratio, the effects of initial solution pH, temperature, initial concentration and contact time on adsorption towards MB were explored systematically. The results indicated that the adsorption capacity at 275 K could reach up to 598.8 mg g-1, the adsorption behavior followed the pseudo-second-order kinetic model and the equilibrium adsorption data fitted the Langmuir isotherm well. Thermodynamic and kinetic analyses revealed that adsorption is an exothermic, spontaneous and physisorption process.

Preparation of improved gluten material and its adsorption behavior for congo red from aqueous solution.

Improved gluten materials were prepared using bio-fermentation and acid bath coagulation methods for congo red adsorption. After comparison, the method of acid bath coagulation with better effect was selected and further preparations of improved gluten materials were achieved under different acid coagulation baths and the solid-liquid ratios. Finally, particular adsorption properties were studied using the sample of improved gluten material with the acid coagulation bath of HCl and the solid-liquid ratio of 1:5. Influence parameters on the congo red adsorption such as temperature, dose, contact time and pH were discussed. The adsorption properties of the improved gluten material were investigated by isotherm (the Langmuir model and the Freundlich model), kinetics (the pseudo-first-order, pseudo-second-order and intra-particle diffusion equations) and thermodynamic analysis. The results showed that this improved gluten material was an efficient adsorbent for removal of congo red.

Review of Carbon and Graphene Quantum Dots for Sensing.

Carbon and graphene quantum dots (CQDs and GQDs), known as zero-dimensional (0D) nanomaterials, have been attracting increasing attention in sensing and bioimaging. Their unique electronic, fluorescent, photoluminescent, chemiluminescent, and electrochemiluminescent properties are what gives them potential in sensing. In this Review, we summarize the basic knowledge on CQDs and GQDs before focusing on their application to sensing thus far followed by a discussion of future directions for research into CQDs- and GQD-based nanomaterials in sensing. With regard to the latter, the authors suggest that with the potential of these nanomaterials in sensing more research is needed on understanding their optical properties and why the synthetic methods influence their properties so much, into methods of surface functionalization that provide greater selectivity in sensing and into new sensing concepts that utilize the virtues of these nanomaterials to give us new or better sensors that could not be achieved in other ways.

Modulation of PTEN by hexarelin attenuates coronary artery ligation-induced heart failure in rats

Background/aim: Hexarelin is a synthetic growth hormone-releasing peptide that exerts cardioprotective effects. However, its cardioprotective effect against heart failure (HF) is yet to be explained. This study investigated the therapeutic role of hexarelin and the mechanisms underlying its cardioprotective effects against coronary artery ligation (CAL)-induced HF in rats. Materials and methods: Rats with four weeks of permanent CAL, induced myocardial infarction, and HF were randomly separated into four groups: the control group (Ctrl), sham group (Sham), hexarelin treatment group (HF + Hx), and heart failure group (HF). The rats were treated with subcutaneous injection of hexarelin (100 µg/kg) in the treatment group or saline in the other groups twice a day for 30 days. Left ventricular (LV) function, oxidative stress, apoptosis, molecular analyses, and cardiac structural and pathological changes in rats were assessed. Results: The treatment of HF rats with hexarelin significantly induced the upregulation of phosphatase and tensin homologue (PTEN) expression and inhibited the phosphorylation of protein kinase B (Akt) and mammalian target of rapamycin (mTOR) to significantly improve LV function, ameliorate myocardial remodeling, and reduce oxidative stress. Conclusion: These findings indicate that hexarelin attenuates CAL-induced HF in rats by ameliorating myocardial remodeling, LV dysfunction, and oxidative stress via the upmodulation of PTEN signaling and downregulation of the Akt/mTOR signaling pathway.

Direct generation of Ag nanoclusters on reduced graphene oxide nanosheets for efficient catalysis, antibacteria and photothermal anticancer applications.

There is considerable interest in understanding the catalytical, antibacterial, and photo-thermal properties of Ag nanoparticles. Herein, a simple, scalable and effective method is explored to generate Ag nanoclusters (∼3.57 nm) directly on reduced graphene oxide (rGO) (denoted as AgNC/GSH-rGO) using glutathione (GSH) as a green and mild co-reduction agent. Due to the good electrical conductivity of rGO, the extremely small particle size of Ag nanoclusters and the synergistic effect between Ag nanoclusters and rGO, high catalytic activity for reduction of 4-nitrophenol is achieved for AgNC/GSH-rGO at a very low Ag nanoclusters loading of 8.67 wt% on rGO. The conversion could reach 96.69% in 16 min and the apparent rate constant based on rGO is derived to be 0.55 min-1 when the concentration of AgNC/GSH-rGO is 0.04 mg mL-1. Moreover, the AgNC/GSH-rGO nanohybrids are also proven to be an efficient antibacterial and photothermal ablation agent for avoiding wound infection and cancer therapy applications.

Exogenous H2S contributes to recovery of ischemic post-conditioning-induced cardioprotection by decrease of ROS level via down-regulation of NF-κB and JAK2-STAT3 pathways in the aging cardiomyocytes.

BACKGROUND: Hydrogen sulfide (H2S), a third member of gasotransmitter family along with nitric oxide and carbon monoxide, generated from mainly catalyzed by cystathionine-lyase, possesses important functions in the cardiovascular system. Ischemic post-conditioning (PC) strongly protects against the hypoxia/reoxygenation (H/R)-induced injury and apoptosis of cardiomyocytes. However, PC protection is ineffective in the aging cardiomyocytes. Whether H2S restores PC-induced cardioprotection by decrease of reactive oxygen species (ROS) level in the aging cardiomyocytes is unknown. METHODS: The aging cardiomyocytes were induced by treatment of primary cultures of neonatal cardiomyocytes using d-galactose and were exposed to H/R and PC protocols. Cell viability was observed by CCK-8 kit. Apoptosis was detected by Hoechst 33342 staining and flow cytometry. ROS level was analyzed using spectrofluorimeter. Related protein expressions were detected through Western blot. RESULTS: Treatment of NaHS (a H2S donor) protected against H/R-induced apoptosis, cell damage, the expression of cleaved caspase-3 and cleaved caspase-9, the release of cytochrome c (Cyt c). The supplementation of NaHS also decreased the activity of LDH and CK, MDA contents, ROS levels and the phosphorylation of IκBα, NF-κB, JNK2 and STAT3, and increased cell viability, the expression of Bcl-2, the activity of SOD, CAT and GSH-PX. PC alone did not provide cardioprotection in H/R-treated aging cardiomyocytes, which was significantly restored by the addition of NaHS. The beneficial role of NaHS was similar to the supply of N-acetyl-cysteine (NAC, an inhibitor of ROS), Ammonium pyrrolidinedithiocarbamate (PDTC, an inhibitor of NF-κB) and AG 490 (an inhibitor of JNK2), respectively, during PC. CONCLUSION: Our results suggest that exogenous H2S contributes to recovery of PC-induced cardioprotection by decrease of ROS level via down-regulation of NF-κB and JAK2/STAT3 pathways in the aging cardiomyocytes.

Spermine inhibits Endoplasmic Reticulum Stress-induced Apoptosis: a New Strategy to Prevent Cardiomyocyte Apoptosis.

BACKGROUND/AIMS: Endoplasmic reticulum stress (ERS) plays an important role in the progression of acute myocardial infarction (AMI), in part by mediating apoptosis. Polyamines, including putrescine, spermidine, and spermine, are polycations with anti-oxidative, anti-aging, and cell growth-promoting activities. This study aimed to determine the mechanisms by which spermine protects against ERS-induced apoptosis in rats following AMI. METHODS AND RESULTS: AMI was established by ligation of the left anterior descending coronary artery (LAD) in rats, and exogenous spermine was administered by intraperitoneal injection (2.5 mg/ml daily for 7 days pre-AMI). Spermine treatment limited infarct size, attenuated cardiac troponin I and creatinine kinase-MB release, improved cardiac function, and decreased ERS and apoptosis related protein expression. Isolated cardiomyocytes subjected to hypoxia showed significant increase in reactive oxygen species (ROS) and the expression of apoptosis and ERS related proteins; these effects occurred through PERK and eIF2α phosphorylation. The addition of spermine attenuated cardiomyocyte apoptosis, suppressed the production of ROS, and inhibited ERS related pathways. CONCLUSIONS: Spermine was an effective pre-treatment strategy to attenuate cardiac ERS injury in rats, and the cardioprotective mechanism occurring through inhibition of ROS production and down regulation of the PERK-eIF2α pathway. These findings provide a novel target for the prevention of apoptosis in the setting of AMI.

Exogenous spermine ameliorates high glucose-induced cardiomyocytic apoptosis via decreasing reactive oxygen species accumulation through inhibiting p38/JNK and JAK2 pathways.

Reactive oxygen species (ROS) generation has been suggested to play a vital role in the initiation and progression of diabetic cardiomyopathy, a major complication of diabetes mellitus. Recent studies reveal that spermine possesses proliferative, antiaging and antioxidative properties. Thus, we hypothesized that spermine could decrease apoptosis via suppressing ROS accumulation induced by high glucose (HG) in cardiomyocytes. Cultured neonatal rat ventricle cardiomyocytes were treated with normal glucose (NG) (5 mM) or HG (25 mM) in the presence or absence of spermine for 48 h. The cell activity, apoptosis, ROS production, T-SOD and GSH activities, MDA content and GSSG level were assessed. The results showed that HG induced lipid peroxidation and the increase of intracellular ROS formation and apoptosis in primary cardiomyocytes. Spermine could obviously improve the above-mentioned changes. Western blot analysis revealed that spermine markedly inhibited HG-induced the phosphorylation of p38/JNK MAPKs and JAK2. Moreover, spermine had better antioxidative and anti-apoptotic effects than N-acetyl-L-cysteine (NAC). Taken together, the present data suggested that spermine could suppress ROS accumulation to decrease cardiomyocytes apoptosis in HG condition, which may be attributed to the inhibition of p38/JNK and JAK2 activation and its natural antioxidative property. Our findings may highlight a new therapeutic intervention for the prevention of diabetic cardiomyopathy.

[The protective effect of DR2 activation on hypoxia/reperfusion injury in the neonatal rat cardiomyocytes and related mechanism].

OBJECTIVE: To observe the effect of dopamine receptor (DR2) activation on hypoxia/reperfusion injury (HRI) in the neonatal rat cardiomyocytes, and to explore its mechanism. METHODS: The hypoxia/reperfusion (H/R) injury model was established in primarily cultured neonatal rat cardiomyocytes, and randomly assigned: control, H/R, bromocriptine (Bro) and haloperidol (Hal) groups. The cell apoptosis was detected using inverted microscope, transmission electron microscope and flow cytometry (FCM). The lactate dehydrogenase(LDH) and superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in cell medium were analyzed. The expression of mRNA and protein of caspase-3, caspase-8, caspase-9, Fas, Fas-L, Cyt C and Bcl-2 were detected by RT-PCR and Western blot, respectively. RESULTS: Compared with the control group, apoptosis rate, LDH activity, MDA content and the expression of pro-apoptotic factors and anti-apoptotic factors were increased, but SOD activity was decreased in H/R group. Compared with the H/R group, all index above-mentioned were down-regulated or reversed in Bro-group, and had no obvious differences in Hal-group. CONCLUSION: The neonatal rat cardiomyocytes injury and apoptosis caused by hypoxia/reperfusion can be inhibited with DR2 activation, which mechanism is related to scavenging oxygen radical.

Hexarelin suppresses cardiac fibroblast proliferation and collagen synthesis in rat.

Abnormal growth of cardiac fibroblasts is critically involved in the pathophysiology of cardiac hypertrophy/remodeling. Hexarelin is a synthetic growth hormone secretagogue (GHS), which possesses a variety of cardiovascular protective activities mediated via the GHS receptor (GHSR), including improving cardiac dysfunction and remodeling. The cellular and molecular mechanisms underlying the effect of GHS on cardiac fibrosis are, however, not clear. In this report, cultured cardiac fibroblasts from 8-day-old rats were stimulated with ANG II or FCS to induce proliferation. The fibroblast proliferation and DNA and collagen synthesis were evaluated utilizing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, (3)H-thymidine incorporation, and (3)H-proline incorporation. The level of mRNA of transforming growth factor (TGF)-beta was evaluated by RT-PCR, and the active TGF-beta1 release from cardiac fibroblasts was evaluated by ELISA. The level of cellular cAMP was measured by radioimmunoassay. In addition, the effects of 3,7-dimethyl-l-propargylxanthine (DMPX; a specific adenosine receptor A(2)R antagonist) and 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; a specific A(1)R antagonist) were tested. It was found that incubation with 10(-7) mol/l hexarelin for 24 h 1) inhibited the ANG II-induced proliferation and collagen synthesis and the 5% FCS- and TGF-beta-induced increase of DNA synthesis in cardiac fibroblast and 2) reduced ANG II-induced upregulation of TGF-beta mRNA expression and active TGF-beta1 release from fibroblasts. Hexarelin increased the cellular level of cAMP in cardiac fibroblasts. DMPX (10(-8) mol/l) but not DPCPX abolished the effect of hexarelin on cardiac fibroblast DNA synthesis. It is concluded that hexarelin inhibits DNA and collagen synthesis and proliferation of cardiac fibroblasts through activation of both GHSR and A(2)R and diminishment of ANG II-induced increase in TGF-beta expression and release.