Theoretical Study of Hydroxylation of α- and ß-Pinene by a Cytochrome P450 Monooxygenase Model.

Previous studies on biocatalytic transformations of pinenes by cytochrome P450 (CYP) enzymes reveal the formation of different oxygenated products from a single substrate due to the multistate reactivity of CYP and the many reactive sites in the pinene scaffold. Up until now, the detailed mechanism of these biocatalytic transformations of pinenes have not been reported. Hereby, we report a systematic theoretical study of the plausible hydrogen abstraction and hydroxylation reactions of α- and ß-pinenes by CYP using the density functional theory (DFT) method. All DFT calculations in this study were based on B3LYP/LAN computational methodology using the Gaussian09 software. We used the B3LYP functional with corrections for dispersive forces, BSSE, and anharmonicity to study the mechanism and thermodynamic properties of these reactions using a bare model (without CYP) and a pinene-CYP model. According to the potential energy surface and Boltzmann distribution for radical conformers, the major reaction products of CYP-catalyzed hydrogen abstraction from ß-pinene are the doublet trans (53.4%) and doublet cis (46.1%) radical conformer at delta site. The formation of doublet cis/trans hydroxylated products released a total Gibbs free energy of about 48 kcal/mol. As for alpha pinene, the most stable radicals were trans-doublet (86.4%) and cis-doublet (13.6%) at epsilon sites, and their hydroxylation products released a total of ~50 kcal/mol Gibbs free energy. Our results highlight the likely C-H abstraction and oxygen rebounding sites accounting for the multi-state of CYP (doublet, quartet, and sextet spin states) and the formation of different conformers due to the presence of cis/trans allylic hydrogen in α-pinene and ß-pinene molecules.

Neuropathic pain: Mechanisms and therapeutic strategies.

The physiopathology and neurotransmission of pain are of an owe inspiring complexity. Our ability to satisfactorily suppress neuropathic or other forms of chronic pain is limited. The number of pharmacodynamically distinct and clinically available medications is low and the successes achieved modest. Pain Medicine practitioners are confronted with the ethical dichotomy imposed by Hippocrates: On one hand the mandate of primum non nocere, on the other hand, the promise of heavenly joys if successful divinum est opus sedare dolorem. We briefly summarize the concepts associated with nociceptive pain from nociceptive input (afferents from periphery), modulatory output [descending noradrenergic (NE) and serotoninergic (5-HT) fibers] to local control. The local control is comprised of the "inflammatory soup" at the site of pain origin and synaptic relay stations, with an ATP-rich environment promoting inflammation and nociception while an adenosine-rich environment having the opposite effect. Subsequently, we address the transition from nociceptor pain to neuropathic pain (independent of nociceptor activation) and the process of sensitization and pain chronification (transient pain progressing into persistent pain). Having sketched a model of pain perception and processing we attempt to identify the sites and modes of action of clinically available drugs used in chronic pain treatment, focusing on adjuvant (co-analgesic) medication.

Implementation of Learning Communities at Khalifa University College of Medicine and Health Sciences, Abu Dhabi, United Arab Emirates.

Learning community programs have been widely implemented in higher education institutions, including many accredited medical schools in North America. Learning communities have been shown to create a sense of belonging, enhance teaching and learning, and promote an inclusive educational environment that reinforces collaboration, professionalism, and wellbeing. Based on their demonstrated success, a learning community program was included in the development of Khalifa University College of Medicine and Health Sciences (KU CMHS), the first medical school in the capital city of Abu Dhabi and the first to offer a postbaccalaureate, Doctor of Medicine (MD) degree in the United Arab Emirates (UAE). Named the Falcon Learning Communities (FLCs), the program adopted the core values of the Learning Communities Institute and integrated them into curricular, co-curricular, and extra-curricular programming. This paper presents an overview on the development of the FLC program, its implication for both students and faculty, preliminary feedback from teachers and learners, and considerations for future work.

Metabolic conversion of ß-pinene to ß-ionone in rats.

Exposure to or ingestion of turpentine can alter the scent of urine, conferring it a flowery, violet-like scent. Turpentine's effect on urine was initially noticed after its use either as medicine or as a preservative in winemaking. Regardless of the source of exposure, the phenomenon requires metabolic conversion of turpentine component(s) to ionone, the molecule mainly responsible for the scent of violets.The purpose of this study was to identify the presence of ionone in the urine of rats that received ß-pinene, and thus to demonstrate that the postulated conversion occurs.We treated rats intraperitoneally with normal saline (negative control), ß-ionone (positive control), low-dose ß-pinene (1/3 of LD50), and high-dose ß-pinene (1/2 of LD50). Urine samples were collected up to 72 h after administration of the compounds, followed by gas chromatography/mass spectrometry identification of the presence of ionone.ß-Ionone was found in the urine of rats exposed to both low and high doses of ß-pinene. In contrast, α-ionone appears unlikely to have been formed in rats exposed to either low or high doses of ß-pinene. ß-pinene was converted to ß-ionone, followed by partial excretion in the urine of rats. ß-Ionone is a minor metabolite of ß-pinene.

Discovery of novel class of histone deacetylase inhibitors as potential anticancer agents.

Selective inhibition of histone deacetylases (HDACs) is an important strategy in the field of anticancer drug discovery. However, lack of inhibitors that possess high selectivity toward certain HDACs isozymes is associated with adverse side effects that limits their clinical applications. We have initiated a collaborative initiatives between multi-institutions aimed at the discovery of novel and selective HDACs inhibitors. To this end, a phenotypic screening of an in-house pilot library of about 70 small molecules against various HDAC isozymes led to the discovery of five compounds that displayed varying degrees of HDAC isozyme selectivity. The anticancer activities of these molecules were validated using various biological assays including transcriptomic studies. Compounds 15, 14, and 19 possessed selective inhibitory activity against HDAC5, while 28 displayed selective inhibition of HDAC1 and HDAC2. Compound 22 was found to be a selective inhibitor for HDAC3 and HDAC9. Importantly, we discovered a none-hydroxamate based HDAC inhibitor, compound 28, representing a distinct chemical probe of HDAC inhibitors. It contains a trifluoromethyloxadiazolyl moiety (TFMO) as a non-chelating metal-binding group. The new compounds showed potent anti-proliferative activity when tested against MCF7 breast cancer cell line, as well as increased acetylation of histones and induce cells apoptosis. The new compounds apoptotic effects were validated through the upregulation of proapoptotic proteins caspases3 and 7 and downregulation of the antiapoptotic biomarkers C-MYC, BCL2, BCL3 and NFĸB genes. Furthermore, the new compounds arrested cell cycle at different phases, which was confirmed through downregulation of the CDK1, 2, 4, 6, E2F1 and RB1 proteins. Taken together, our findings provide the foundation for the development of new chemical probes as potential lead drug candidates for the treatment of cancer.

Remedia Sternutatoria over the Centuries: TRP Mediation.

Sneezing (sternutatio) is a poorly understood polysynaptic physiologic reflex phenomenon. Sneezing has exerted a strange fascination on humans throughout history, and induced sneezing was widely used by physicians for therapeutic purposes, on the assumption that sneezing eliminates noxious factors from the body, mainly from the head. The present contribution examines the various mixtures used for inducing sneezes (remedia sternutatoria) over the centuries. The majority of the constituents of the sneeze-inducing remedies are modulators of transient receptor potential (TRP) channels. The TRP channel superfamily consists of large heterogeneous groups of channels that play numerous physiological roles such as thermosensation, chemosensation, osmosensation and mechanosensation. Sneezing is associated with the activation of the wasabi receptor, (TRPA1), typical ligand is allyl isothiocyanate and the hot chili pepper receptor, (TRPV1), typical agonist is capsaicin, in the vagal sensory nerve terminals, activated by noxious stimulants.

The action of aripiprazole and brexpiprazole at the receptor level in singultus.

The hiccup (Latin singultus) is an involuntary periodic contraction of the diaphragm followed by glottic closure, which can be a rare side effect of aripiprazole. In contrast to the structurally closely related aripiprazole, brexpiprazole was not associated with this particular adverse drug reaction. Having two very similar drugs that differ in their ability to induce hiccups represents a unique opportunity to gain insight into the receptors involved in the pathophysiology of the symptom and differences in clinical effects between aripiprazole and brexpiprazole. The overlap between maneuvers used to terminate paroxysmal supraventricular tachycardia and those employed to terminate bouts of hiccups suggests that activation of efferent vagal fibers can be therapeutic in both instances. Recent work seems to support a pivotal role for serotonin receptors in such vagal activation. It is unlikely that a unique receptor-drug interaction could explain the different effects of the examined drugs on hiccup. The different effect is most likely the consequence of several smaller effects at more than one receptor. Brexpiprazole is a highly affine (potent) α2C antagonist and, therefore, also an indirect 5-HT1A agonist. In contrast, aripiprazole is a partial 5-HT1A agonist (weak antagonist) and an HT3 antagonist. Activation of 5-HT1A receptors enhances vagal activity while HT3 blockade reduces it. Vagus nerve activation is therapeutic for hiccups. A definitive answer continues to be elusive.

Ionone Is More than a Violet's Fragrance: A Review.

The term ionone is derived from "iona" (Greek for violet) which refers to the violet scent and "ketone" due to its structure. Ionones can either be chemically synthesized or endogenously produced via asymmetric cleavage of ß-carotene by ß-carotene oxygenase 2 (BCO2). We recently proposed a possible metabolic pathway for the conversion of α-and ß-pinene into α-and ß-ionone. The differences between BCO1 and BCO2 suggest a unique physiological role of BCO2; implying that ß-ionone (one of BCO2 products) is involved in a prospective biological function. This review focuses on the effects of ionones and the postulated mechanisms or signaling cascades involved mediating these effects. ß-Ionone, whether of an endogenous or exogenous origin possesses a range of pharmacological effects including anticancer, chemopreventive, cancer promoting, melanogenesis, anti-inflammatory and antimicrobial actions. ß-Ionone mediates these effects via activation of olfactory receptor (OR51E2) and regulation of the activity or expression of cell cycle regulatory proteins, pro-apoptotic and anti-apoptotic proteins, HMG-CoA reductase and pro-inflammatory mediators. α-Ionone and ß-ionone derivatives exhibit anti-inflammatory, antimicrobial and anticancer effects, however the corresponding structure activity relationships are still inconclusive. Overall, data demonstrates that ionone is a promising scaffold for cancer, inflammation and infectious disease research and thus is more than simply a violet's fragrance.

Impact of COVID-19 Pandemic Burnout on Cardiovascular Risk in Healthcare Professionals Study Protocol: A Multicenter Exploratory Longitudinal Study.

Introduction: The coronavirus disease 2019 (COVID-19) pandemic has created new and unpredictable challenges for healthcare systems. Healthcare professionals are heavily affected by this rapidly changing situation, especially frontline healthcare professionals who are directly engaged in the diagnosis, treatment, and care of patients with COVID-19 and may experience psychological burdens. The objective of this study is to explore the evolution of psychosocial, cardiovascular, and immune markers in healthcare professionals with different levels of exposure to the COVID-19 pandemic. Methods and Analysis: This is a STROBE compliant, blended, exploratory study involving online and onsite approaches that use wearable monitoring. A planned random probability sample of residents, staff physicians, nurses, and auxiliary healthcare professionals will be recruited. The study sample will be stratified by exposure to the COVID-19 pandemic. As a first step, recruitment will be conducted online, with e-consent and using e-surveys with Maslach Burnout Inventory, Fuster-BEWAT score, and sociodemographic characteristics. Onsite visits will be planned for the second step where participants will receive a wearable setup that will measure heart rate, actimetry, and sleep quality monitoring, which will be used together with blood sampling for immune biomarkers. Steps 1 and 2 will then be repeated at 2-3 months, and 6 months. Power BI and Tableau will be used for data visualization, while front-end data capture will be used for data collection using specific survey/questionnaires, which will enable data linkage between e-surveys, internet of things wearable devices, and clinical laboratory data. Clinical Trial Registration: ClinicalTrials.gov; Identifier: NCT04422418.

A key metabolic integrator, coenzyme A, modulates the activity of peroxiredoxin 5 via covalent modification.

Peroxiredoxins (Prdxs) are antioxidant enzymes that catalyse the breakdown of peroxides and regulate redox activity in the cell. Peroxiredoxin 5 (Prdx5) is a unique member of Prdxs, which displays a wider subcellular distribution and substrate specificity and exhibits a different catalytic mechanism when compared to other members of the family. Here, the role of a key metabolic integrator coenzyme A (CoA) in modulating the activity of Prdx5 was investigated. We report for the first time a novel mode of Prdx5 regulation mediated via covalent and reversible attachment of CoA (CoAlation) in cellular response to oxidative and metabolic stress. The site of CoAlation in endogenous Prdx5 was mapped by mass spectrometry to peroxidatic cysteine 48. By employing an in vitro CoAlation assay, we showed that Prdx5 peroxidase activity is inhibited by covalent interaction with CoA in a dithiothreitol-sensitive manner. Collectively, these results reveal that human Prdx5 is a substrate for CoAlation in vitro and in vivo, and provide new insight into metabolic control of redox status in mammalian cells.

Coenzyme A and protein CoAlation levels are regulated in response to oxidative stress and during morphogenesis in Dictyostelium discoideum.

Dictyostelium discoideum (D. discoideum) is a simple eukaryote with a unique life cycle in which it differentiates from unicellular amoebae into a fruiting body upon starvation. Reactive oxygen species (ROS) have been associated with bacterial predation, as well as regulatory events during D. discoideum development and differentiation. Coenzyme A (CoA) is a key metabolic integrator in all living cells. A novel function of CoA in redox regulation, mediated by covalent attachment of CoA to cellular proteins in response to oxidative or metabolic stress, has been recently discovered and termed protein CoAlation. In this study, we report that the level of CoA and protein CoAlation in D. discoideum are developmentally regulated, and correlate with the temporal expression pattern of genes implicated in CoA biosynthesis during morphogenesis. Furthermore, treatment of growing D. discoideum cells with oxidising agents results in a dose-dependent increase of protein CoAlation. However, much higher concentrations were required when compared to mammalian cells and bacteria. Increased resistance of D. discoideum to oxidative stress induced by H2O2 has previously been attributed to high levels of catalase activity. In support of this notion, we found that H2O2-induced protein CoAlation is significantly increased in CatA-deficient D. discoideum cells. Collectively, this study provides insights into the role of CoA and protein CoAlation in the maintenance of redox homeostasis in amoeba and during D. discoideum morphogenesis.