Radical Cations of the Monomer and van der Waals Dimer of a Methionine Residue as Prototypes of (2 Center–3 Electron) SN and SS Bonds. Molecular Simulations of Their Absorption Spectra in Water

Impact of the virtual anti-hypertensive educational campaign towards knowledge, attitude, and practice of hypertension management during the COVID-19 pandemic

BACKGROUND

One of the efforts to reduce hypertension rates in the community is through an educational campaign that refers to the NIH's National Heart, Lung, and Blood Institute curricula or abbreviated as NHLBI. However, during the coronavirus disease 2019 (COVID-19) pandemic, one of the hardest hit areas is health promotion, and there is a significant obstacle regarding the most effective way to transfer knowledge, attitude and practice towards society without transmitting the virus.

AIM

To evaluate the impact of the virtual anti-hypertensive educational campaign towards knowledge, attitude, and the practice of hypertension management in the primary care setting during the COVID-19 pandemic.

METHODS

An online action research with a randomized crossover-controlled trial using a pretest-posttest control group design. The study was conducted in October 2020-April 2021. The population in this study were patients with hypertension who were treated in the Mojo primary health care setting. A purposive sampling technique was done to receive 110 participants using an online questionnaire and invitation letter.

RESULTS

A total of 110 participants were included in the analysis, 55 in the intervention group and 55 in the control group. Following the Virtual Anti-Hypertensive Educational Campaign implementation, the only parameter that showed significant improvement was knowledge and attitude (P < 0.001). There is no significant change in the practice parameters (P = 0.131).

CONCLUSION

The Virtual Anti-Hypertensive Educational Campaign implementation in our study population seems to be effective to improve knowledge and attitude of participants, nevertheless, this program seems to be ineffective to improve the practice of hypertension management aspect in participants. Future study with longer durations and more comprehensive programs need to be done to scrutinize the clinical impact of this program nationwide.

Final Products of One-Electron Oxidation of Cyclic Dipeptides Containing Methionine Investigated by IRMPD Spectroscopy: Does the Free Radical Choose the Final Compound?

Reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) and the hydroxyl radical (^•OH) have specific functions in biological processes, while their uncontrolled production and reactivity are known to be determining factors in pathophysiology. Methionine (Met) residues act as endogenous antioxidants, when they are oxidized into methionine sulfoxide (MetSO), thus depleting ROS and protecting the protein. We employed tandem mass spectrometry combined with IR multiple photon dissociation spectroscopy to study the oxidation induced by OH radicals produced by γ radiolysis on model cyclic dipeptides c(LMetLMet), c(LMetDMet), and c(GlyMet). Our aim was to characterize the geometries of the oxidized peptides in the gas phase and to understand the relationship between the structure of the 2-center 3-electron (2c-3e) free radical formed in the first step of the oxidation process and the final compound. Density functional theory calculations were performed to characterize the lowest energy structures of the final product of oxidation and to interpret the IR spectra. Collision-induced dissociation tandem mass spectrometry (CID-MS²) experiments of oxidized c(LMetLMet)H⁺ and c(LMetDMet)H⁺ led to the loss of one or two oxidized sulfenic acid molecules, indicating that the addition of one or two oxygen atoms occurs on the sulfur atom of both methionine side chains and no sulfone formation was observed. The CID-MS² fragmentation mass spectrum of oxidized c(GlyMet)H⁺ showed only the loss of one oxidized sulfenic acid molecule. Thus, the final products of oxidation are the same regardless of the structure of the precursor sulfur-centered free radical.

Radiolytic Oxidation of Two Inverse Dipeptides, Methionine-Valine and Valine-Methionine: A Joint Experimental and Computational Study

The two inverse peptides methionine-valine (Met-Val) and valine-methionine (Val-Met) are investigated in an oxidative radiolysis process in water. The OH radical yields products with very different absorption spectra and concentration effects: Met-Val yields one main product with a band at about 400 nm and other products at higher energies; there is no concentration effect. Val-Met yields at least three products, with a striking concentration effect. Molecular simulations are performed with a combination of the Monte Carlo, density functional theory, and reaction field methods. The simulation of the possible transients enables an interpretation of the radiolysis: (1) Met-Val undergoes an H atom uptake leaving mainly a neutral radical with a 2-center-3-electron (2c-3e) SN bond, which cannot dimerize. Other radicals are present at higher energies. (2) Val-Met undergoes mainly an electron uptake leaving a cation monomer with a (2c-3e) SO bond and a cation dimer with a (2c-3e) SS bond. At higher energies, neutral radicals are possible. This cation monomer can transfer a proton toward a neutral peptide, leaving a neutral radical.

Mechanism of (SCN)2·- Formation and Decay in Neutral and Basic KSCN Solution under Irradiation from a Pico- to Microsecond Range

The detailed mechanism of the reaction between SCN^- and the OH^· radical and the formation of the dimer radical (SCN)₂^·- are studied by picosecond pulse radiolysis. First, concentrated SCN^- solutions are used to observe directly the formation and decay of SCNOH^·- in neutral and basic solutions. Then, the spectro-kinetic data, constituting a large matrix of data of the absorbance at different times and different wavelengths, obtained by pulse radiolysis measurements with a streak camera, in neutral and basic SCN^- solutions, are analyzed simultaneously. Data analysis allowed us to deduce the absorption spectra of different radicals with their extinction coefficient and also to determine the rate constants of different reactions involved in the formation and decay of (SCN)₂^·-. Molecular simulations of the absorption spectra of the different species were also performed. The absorption spectrum of the radical SCN^· is determined and is found to be different than that reported previously. It does not present a Gaussian shape centered at 330 nm; the absorption around 310 and 380 nm is not negligible. In addition, in a solution at pH 13, it is found that the (SCN)₂^·- radical is paired with an alkaline cation, inducing a blueshift of the absorption band compared to the free (SCN)₂^·-. Finally, the presence of K⁺ cations catalyzes the disproportionation reaction of (SCN)₂^·- and affects the kinetics.