Direct Regulation of Hyperpolarization-Activated Cyclic-Nucleotide Gated (HCN1) Channels by Cannabinoids.

Cannabinoids are a broad class of molecules that act primarily on neurons, affecting pain sensation, appetite, mood, learning, and memory. In addition to interacting with specific cannabinoid receptors (CBRs), cannabinoids can directly modulate the function of various ion channels. Here, we examine whether cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), the most prevalent phytocannabinoids in Cannabis sativa, can regulate the function of hyperpolarization-activated cyclic-nucleotide-gated (HCN1) channels independently of CBRs. HCN1 channels were expressed in Xenopus oocytes since they do not express CBRs, and the effects of cannabinoid treatment on HCN1 currents were examined by a two-electrode voltage clamp. We observe opposing effects of CBD and THC on HCN1 current, with CBD acting to stimulate HCN1 function, while THC inhibited current. These effects persist in HCN1 channels lacking the cyclic-nucleotide binding domain (HCN1ΔCNBD). However, changes to membrane fluidity, examined by treating cells with TX-100, inhibited HCN1 current had more pronounced effects on the voltage-dependence and kinetics of activation than THC, suggesting this is not the primary mechanism of HCN1 regulation by cannabinoids. Our findings may contribute to the overall understanding of how cannabinoids may act as promising therapeutic molecules for the treatment of several neurological disorders in which HCN function is disturbed.

Identification and Characterization of the Interaction Between the Methyl-7-Guanosine Cap Maturation Enzyme RNMT and the Cap-Binding Protein eIF4E.

The control of RNA metabolism is an important aspect of molecular biology with wide-ranging impacts on cells. Central to processing of coding RNAs is the addition of the methyl-7 guanosine (m7G) "cap" on their 5' end. The eukaryotic translation initiation factor eIF4E directly binds the m7G cap and through this interaction plays key roles in many steps of RNA metabolism including nuclear RNA export and translation. eIF4E also stimulates capping of many transcripts through its ability to drive the production of the enzyme RNMT which methylates the G-cap to form the mature m7G cap. Here, we found that eIF4E also physically associated with RNMT in human cells. Moreover, eIF4E directly interacted with RNMT in vitro. eIF4E is only the second protein reported to directly bind the methyltransferase domain of RNMT, the first being its co-factor RAM. We combined high-resolution NMR methods with biochemical studies to define the binding interfaces for the RNMT-eIF4E complex. Further, we found that eIF4E competes for RAM binding to RNMT and conversely, RNMT competes for binding of well-established eIF4E-binding partners such as the 4E-BPs. RNMT uses novel structural means to engage eIF4E. Finally, we observed that m7G cap-eIF4E-RNMT trimeric complexes form, and thus RNMT-eIF4E complexes may be employed so that eIF4E captures newly capped RNA. In all, we show for the first time that the cap-binding protein eIF4E directly binds to the cap-maturation enzyme RNMT.

Coronavirus Disease 2019 (COVID-19) in Children: Prevalence, Diagnosis, Clinical Symptoms, and Treatment.

In this article, we have reviewed the prevalence, diagnosis, symptoms, and treatment of COVID-19 in children. The incidence of COVID-19 among children under 18 years was 2.1% based on the reported studies, where the mortality rate in the same age group was 0.2%. No death has been reported in children under 9-years old. There are some articles that report children with COVID-19 having symptoms similar to Kawasaki's disease. In these cases, heart complications were observed. The best markers for diagnosing the severity of the disease in children are the levels of bilirubin and hepatic enzymes. Large number of angiotensin converting enzyme 2 (ACE2) receptors on cell surfaces, effective innate immune system, and high level of blood lymphocyte have been reported to be the potent reasons for lower incidence of severe symptoms of COVID-19 among children. Children can very well be the carriers of this virus. Children with severe COVID-19 clinical symptoms, especially those suffering from pneumonia, must be hospitalized similar to adults, while quarantine is required for those having mild symptoms. Antiviral medication (lopinavir, darunavir, favipiravir, remdesivir, ribavirin, oseltamivir, tocilizumab, and umifenovir), ACE inhibitors, interferon-α2b, co-therapy with azithromycin, inhaling iNO, and oxygen therapy can be used for treatment. For the treatment of children without any clinical and infection symptoms, home isolation protocol has been recommended.

A new whole-cell biocatalyst for sulfur dioxide filtering and degradation.

In this study, the interaction of the magnetotactic bacterium with sulfite compounds and their potential to degrade SO2 was investigated using cyclic voltammetry (CV), molecular emission cavity analysis (MECA) and ion-exchange chromatography (IEC). This biofilter was able to degrade SO2 up to 22281 mg m-3 by disproportionation reaction and the formation of S2- and SO42- with ≥99% efficiency. Designed biofilter was able to restart the initial performance at least after seven cycles if it was used at 14-day intervals. According to theoretical studies, the value of mean free energy (E) obtained using the Dubinin-Radushkevich isotherm model was 0.02 kJ mol-1, which is in the range expected for physical adsorption. Designed biofilter can be considered as a powerful tool to degrade SO2 in diverse urban and industrial centers.

Introducing a bioelectrochemical method for highly selective enumeration of magnetotactic bacteria.

In this study, we employed an electrochemical (potentiometric) method to enumerate magnetotactic bacteria (MTB) during its coupling with iodometric titration to obtain a selective, precise and rapid counting system. Oxygen was considered as an important factor for the orientation and movement of MTB towards the magnet-modified indicator electrode. In the direct potentiometry, a linear correlation was detected between potentiometric response and dissolved oxygen (DO) concentrations. By the increase of the DO concentration, potential difference would increase in the range of 4.0 to 20.0 parts per million (ppm) at different pressure conditions. The reliability of the O2 bio-sensing feature provides a selective MTB-based cell enumeration methodology based on indirect potentiometric titration. Furthermore, a five-minute H2-purging resulted in an increase of potentiometric response sensitivity arising from the decrease in DO concentration of the electrolyte solution. Results were also investigated by zeta potential difference, which show the effect of charge density of MTB in presence of DO. Zeta potential was increased proportionally by addition of the MTB population. Regarding the reliability of the suggested method, data obtained by the designed system showed no statistical difference from those obtained by the most common procedure in microbiology for enumeration of bacteria, known as colony forming unit (CFU) method.

Purification, Characterization and Mechanistic Evaluation of Angiotensin Converting Enzyme Inhibitory Peptides Derived from Zizyphus Jujuba Fruit.

The synthetic Angiotensin Converting Enzyme (ACE) inhibitors have side effects and hence demands for natural ACE inhibitors have been rising. The aim of this study is to purify and introduce natural ACE inhibitors extracted from Zizyphus jujuba fruits. Proteins from Zizyphus jujuba were lysed by trypsin, papain and their combination. Acquired peptides were purified and evaluated for ACE inhibitory activity. Peptide fractions with inhibitory activity were sequenced using tandem mass spectrometry. To elucidate the mode of peptide binding to ACE, homology modeling, molecular docking and molecular dynamics simulation were performed. Amino acid sequence of F2 and F4 peptides, which were the most active hydrolysates, were determined to be IER and IGK with the IC50 values of 0.060 and 0.072 mg/ml, respectively. Results obtained by computational analysis revealed that similar to the common ACE competitive inhibitors such as captopril, IER tripeptide binds to the enzyme active site, in vicinity of the zinc binding site, and occupies the S1 and S2' subsites. Binding occurs through hydrogen bonding with Gln293, Lys522, His524, Tyr531 and also several hydrophobic interactions. Collectively, these findings indicate that IER tripeptide inhibits the rabbit ACE enzyme through a competitive mechanism of inhibition with IC50 values in the millimolar range.

Evaluation of the Bioactive Potential of Secondary Metabolites Produced by a New Marine Micrococcus Species Isolated from the Persian Gulf.

BACKGROUND: In the present work, a newly isolated marine bacterium, Micrococcus sp. MP76, from coastal area of Persian Gulf around Bushehr province, Iran, was identified with the ability to produce bioactive compounds. METHODS: The pigment production was optimized by changing carbon and nitrogen sources in bacterial growth media at 28°C and 220 rpm for 5 days. Partial purification of the pigment was carried out using suitable solvents. RESULTS: Maximum pigment extract was achieved (1.4 g/l) when cultured in the medium containing 0.5% (v/v) molasses, 0.5% (w/v) peptone, 1% (w/v) sea salt, 0.01% (w/v) potassium phosphate, and 0.05% (w/v) yeast extract, pH=7.0. Antibacterial effect assessment of the extract against pathogenic bacteria revealed the MIC values in the range of 4.2-7.5 mg/ml depending on different pathogens. The pigment extracted from medium supplemented by molasses and ammonium sulfate had 81% radical scavenging activity, and its IC50 value was 0.28 mg/ml. CONCLUSION: The newly isolated strain of Micrococcus genus from the Persian Gulf revealed a valuable source to access worth medicinal ingredients when cultured under optimized conditions.

Influence of different amino acid groups on the free radical scavenging capability of multi walled carbon nanotubes.

Multi-walled carbon nanotubes (MWCNTs) were functionalized with a series of amino acids (lysine, arginine, cysteine, histidine, and aspartic acid) by sonication. Surface functional groups of the treated MWCNTs were investigated by infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The results indicated the formation of various amino acid functionalities on the MWCNT surface, as well as the improved dispersion of MWCNTs in water. After functionalization, the antioxidant activity of all treated samples was analyzed using 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and hydroxyl radical scavenging, metal ion chelating, and reducing power assays. The antioxidant activity of the functionalized MWCNTs was 2-2.5 times greater than that of reduced glutathione (GSH) in ABTS radical scavenging, 1.5-5 times greater than that of GSH in reducing power, 1.3-1.8 times greater than that of butylated hydroxyanisole (BHA) in DPPH scavenging, and 3-10 times greater than that of GSH in hydroxyl radical scavenging. Accordingly, the amino acid-functionalized MWCNTs were appeared to be more potent than BHA and GSH synthetic antioxidants, and can thus be considered as excellent antioxidants to scavenge free radicals.