Organoiridium complexes : anticancer agents and catalysts

Iridium is a relatively rare precious heavy metal, only slightly less dense than osmium. Researchers have long recognized the catalytic properties of square-planar Ir(I) complexes, such as Crabtree's hydrogenation catalyst, an organometallic complex with cyclooctadiene, phosphane, and pyridine ligands. More recently, chemists have developed half-sandwich pseudo-octahedral pentamethylcyclopentadienyl Ir(III) complexes containing diamine ligands that efficiently catalyze transfer hydrogenation reactions of ketones and aldehydes in water using H2 or formate as the hydrogen source. Although sometimes assumed to be chemically inert, the reactivity of low-spin 5d(6) Ir(III) centers is highly dependent on the set of ligands. Cp* complexes with strong σ-donor C^C-chelating ligands can even stabilize Ir(IV) and catalyze the oxidation of water. In comparison with well developed Ir catalysts, Ir-based pharmaceuticals are still in their infancy. In this Account, we review recent developments in organoiridium complexes as both catalysts and anticancer agents. Initial studies of anticancer activity with organoiridium complexes focused on square-planar Ir(I) complexes because of their structural and electronic similarity to Pt(II) anticancer complexes such as cisplatin. Recently, researchers have studied half-sandwich Ir(III) anticancer complexes. These complexes with the formula [(Cp(x))Ir(L^L')Z](0/n+) (with Cp* or extended Cp* and L^L' = chelated C^N or N^N ligands) have a much greater potency (nanomolar) toward a range of cancer cells (especially leukemia, colon cancer, breast cancer, prostate cancer, and melanoma) than cisplatin. Their mechanism of action may involve both an attack on DNA and a perturbation of the redox status of cells. Some of these complexes can form Ir(III)-hydride complexes using coenzyme NAD(P)H as a source of hydride to catalyze the generation of H2 or the reduction of quinones to semiquinones. Intriguingly, relatively unreactive organoiridium complexes containing an imine as a monodentate ligand have prooxidant activity, which appears to involve catalytic hydride transfer to oxygen and the generation of hydrogen peroxide in cells. In addition, researchers have designed inert Ir(III) complexes as potent kinase inhibitors. Octahedral cyclometalated Ir(III) complexes not only serve as cell imaging agents, but can also inhibit tumor necrosis factor α, promote DNA oxidation, generate singlet oxygen when photoactivated, and exhibit good anticancer activity. Although relatively unexplored, organoiridium chemistry offers unique features that researchers can exploit to generate novel diagnostic agents and drugs with new mechanisms of action

Impact of the COVID-19 pandemic on interventional cardiology fellowship training in the New York metropolitan area: A perspective from the United States epicenter

© 2020 Wiley Periodicals, Inc. Background: The healthcare burden posed by the coronavirus disease 2019 (COVID-19) pandemic in the New York Metropolitan area has necessitated the postponement of elective procedures resulting in a marked reduction in cardiac catheterization laboratory (CCL) volumes with a potential to impact interventional cardiology (IC) fellowship training. Methods: We conducted a web-based survey sent electronically to 21 Accreditation Council for Graduate Medical Education accredited IC fellowship program directors (PDs) and their respective fellows. Results: Fourteen programs (67%) responded to the survey and all acknowledged a significant decrease in CCL procedural volumes. More than half of the PDs reported part of their CCL being converted to inpatient units and IC fellows being redeployed to COVID-19 related duties. More than two-thirds of PDs believed that the COVID-19 pandemic would have a moderate (57%) or severe (14%) adverse impact on IC fellowship training, and 21% of the PDs expected their current fellows\u27 average percutaneous coronary intervention (PCI) volume to be below 250. Of 25 IC fellow respondents, 95% expressed concern that the pandemic would have a moderate (72%) or severe (24%) adverse impact on their fellowship training, and nearly one-fourth of fellows reported performing fewer than 250 PCIs as of March 1st. Finally, roughly one-third of PDs and IC fellows felt that there should be consideration of an extension of fellowship training or a period of early career mentorship after fellowship. Conclusions: The COVID-19 pandemic has caused a significant reduction in CCL procedural volumes that is impacting IC fellowship training in the NY metropolitan area. These results should inform professional societies and accreditation bodies to offer tailored opportunities for remediation of affected trainees

Mendelian randomization analyses implicate biogenesis of translation machinery in human aging

Reduced provision of protein translation machinery promotes healthy aging in a number of animal models. In humans, however, inborn impairments in translation machinery are a known cause of several developmental disorders, collectively termed ribosomopathies. Here, we use casual inference approaches in genetic epidemiology to investigate whether adult, tissue-specific biogenesis of translation machinery drives human aging. We assess naturally occurring variation in the expression of genes encoding subunits specific to the two RNA polymerases (Pols) that transcribe ribosomal and transfer RNAs, namely Pol I and III, and the variation in expression of ribosomal protein (RP) genes, using Mendelian randomization. We find each causally associated with human longevity (β = −0.15 ± 0.047, P = 9.6 × 10−4, q = 0.015; β = −0.13 ± 0.040, P = 1.4 × 10−3, q = 0.023; β = −0.048 ± 0.016, P = 3.5 × 10−3, q = 0.056, respectively), and this does not appear to be mediated by altered susceptibility to a single disease. We find that reduced expression of Pol III, RPs, or Pol I promotes longevity from different organs, namely visceral adipose, liver, and skeletal muscle, echoing the tissue specificity of ribosomopathies. Our study shows the utility of leveraging genetic variation in expression to elucidate how essential cellular processes impact human aging. The findings extend the evolutionary conservation of protein synthesis as a critical process that drives animal aging to include humans

Eugenia jambolana Lam. Berry Extract Inhibits Growth and Induces Apoptosis of Human Breast Cancer but Not Non-Tumorigenic Breast Cells

The ripe purple berries of the native Indian plant Eugenia jambolana Lam., known as Jamun, are popularly consumed and available in the United States in Florida and Hawaii. Despite the growing body of data on the chemopreventive potential of edible berry extracts, there is paucity of such data for Jamun fruit. Therefore our laboratory initiated the current study with the following objectives: (1) to prepare a standardized Jamun fruit extract (JFE) for biological studies and (2) to investigate the antiproliferative and pro-apoptotic effects of JFE in estrogen dependent/aromatase positive (MCF-7aro), and estrogen independent (MDA-MB-231) breast cancer cells, and in a normal/nontumorigenic (MCF-10A) breast cell line. JFE was standardized to anthocyanin content using the pH differential method, and individual anthocyanins were identified by high performance liquid chromatography with ultraviolet (HPLC−UV) and tandem mass spectrometry (LC−MS/MS) methods. JFE contained 3.5% anthocyanins (as cyanidin-3-glucoside equivalents) which occur as diglucosides of five anthocyanidins/aglycons: delphinidin, cyanidin, petunidin, peonidin and malvidin. In the proliferation assay, JFE was most effective against MCF-7aro (IC50 = 27 μg/mL), followed by MDA-MB-231 (IC50 = 40 μg/mL) breast cancer cells. Importantly, JFE exhibited only mild antiproliferative effects against the normal MCF-10A (IC50 \u3e 100 μg/mL) breast cells. Similarly, JFE (at 200 μg/mL) exhibited pro-apoptotic effects against the MCF-7aro (p ≤ 0.05) and the MDA-MB-231 (p ≤ 0.01) breast cancer cells, but not toward the normal MCF-10A breast cells. These studies suggest that JFE may have potential beneficial effects against breast cancer

Evaluation of current practices in transcatheter aortic valve implantation: The WRITTEN (WoRldwIde TAVI ExperieNce) survey

Background Transcatheter aortic valve implantation (TAVI) has been adopted worldwide as the standard treatment for severe aortic stenosis in symptomatic patients at prohibitive or high surgical risk, but there are still several areas where consensus and evidence are lacking. The purpose was to obtain a global view of current practice related to TAVI with the potential to identify the main areas of consensus and divergence between centers. Methods An online questionnaire was distributed in centers performing TAVI including a total of 58 questions concerning pre-procedural evaluation, procedural practices and post-procedural management. Results The survey was completed by 250 centers (with a cumulative experience of nearly 70,000 TAVI) from 38 different countries. Heart team meetings and surgical risk scores were routinely performed in most (> 95%) centers, but frailty (44%) and quality of life (28%) assessments were less frequently performed. General anesthesia remained the most frequent type of anesthesia (60% of centers), and significant variability was detected in the examinations for residual aortic regurgitation assessment during the procedure and in post-procedural ECG monitoring and temporary pacemaker implementation (from none to ≥ 72 h post-TAVI). Dual antiplatelet therapy duration post-TAVI was highly variable (1, 3, and ≥ 6 months in 14%, 41% and 32% of centers, respectively) and lack of consensus in antithrombotic regimen was observed in patients with atrial fibrillation requiring anticoagulation therapy (anticoagulation alone, anticoagulation + aspirin, anticoagulation + clopidogrel, and triple therapy in 28%, 37%, 26% and 4% of centers, respectively). Conclusions The WRITTEN survey provided extensive data on current TAVI-related practice and identified important differences between centers in key aspects of pre-, intra-, and post-operative management. This highlights the urgent need for further studies and evidence-based data to guide multiple aspects of the TAVI field

A Microarray-Based Genetic Screen for Yeast Chronological Aging Factors

Model organisms have played an important role in the elucidation of multiple genes and cellular processes that regulate aging. In this study we utilized the budding yeast, Saccharomyces cerevisiae, in a large-scale screen for genes that function in the regulation of chronological lifespan, which is defined by the number of days that non-dividing cells remain viable. A pooled collection of viable haploid gene deletion mutants, each tagged with unique identifying DNA “bar-code” sequences was chronologically aged in liquid culture. Viable mutants in the aging population were selected at several time points and then detected using a microarray DNA hybridization technique that quantifies abundance of the barcode tags. Multiple short- and long-lived mutants were identified using this approach. Among the confirmed short-lived mutants were those defective for autophagy, indicating a key requirement for the recycling of cellular organelles in longevity. Defects in autophagy also prevented lifespan extension induced by limitation of amino acids in the growth media. Among the confirmed long-lived mutants were those defective in the highly conserved de novo purine biosynthesis pathway (the ADE genes), which ultimately produces IMP and AMP. Blocking this pathway extended lifespan to the same degree as calorie (glucose) restriction. A recently discovered cell-extrinsic mechanism of chronological aging involving acetic acid secretion and toxicity was suppressed in a long-lived ade4Δ mutant and exacerbated by a short-lived atg16Δ autophagy mutant. The identification of multiple novel effectors of yeast chronological lifespan will greatly aid in the elucidation of mechanisms that cells and organisms utilize in slowing down the aging process

Regulation of Lifespan, Metabolism, and Stress Responses by the Drosophila SH2B Protein, Lnk

Drosophila Lnk is the single ancestral orthologue of a highly conserved family of structurally-related intracellular adaptor proteins, the SH2B proteins. As adaptors, they lack catalytic activity but contain several protein–protein interaction domains, thus playing a critical role in signal transduction from receptor tyrosine kinases to form protein networks. Physiological studies of SH2B function in mammals have produced conflicting data. However, a recent study in Drosophila has shown that Lnk is an important regulator of the insulin/insulin-like growth factor (IGF)-1 signaling (IIS) pathway during growth, functioning in parallel to the insulin receptor substrate, Chico. As this pathway also has an evolutionary conserved role in the determination of organism lifespan, we investigated whether Lnk is required for normal lifespan in Drosophila. Phenotypic analysis of mutants for Lnk revealed that loss of Lnk function results in increased lifespan and improved survival under conditions of oxidative stress and starvation. Starvation resistance was found to be associated with increased metabolic stores of carbohydrates and lipids indicative of impaired metabolism. Biochemical and genetic data suggest that Lnk functions in both the IIS and Ras/Mitogen activated protein Kinase (MapK) signaling pathways. Microarray studies support this model, showing transcriptional feedback onto genes in both pathways as well as indicating global changes in both lipid and carbohydrate metabolism. Finally, our data also suggest that Lnk itself may be a direct target of the IIS responsive transcription factor, dFoxo, and that dFoxo may repress Lnk expression. We therefore describe novel functions for a member of the SH2B protein family and provide the first evidence for potential mechanisms of SH2B regulation. Our findings suggest that IIS signaling in Drosophila may require the activity of a second intracellular adaptor, thereby yielding fundamental new insights into the functioning and role of the IIS pathway in ageing and metabolism.ISSN:1553-7390ISSN:1553-740

Cardiac damage and quality of life after aortic valve replacement in the PARTNER trials

BACKGROUND The extent of extravalvular cardiac damage is associated with increased risk of adverse events among patients with severe aortic stenosis undergoing aortic valve replacement (AVR). OBJECTIVES The goal was to describe the association of cardiac damage on health status before and after AVR. METHODS Patients from the PARTNER (Placement of Aortic Transcatheter Valves) 2 and 3 trials were pooled and classified by echocardiographic cardiac damage stage at baseline and 1 year as previously described (stage 0-4). We examined the association between baseline cardiac damage and 1-year health status (assessed by the Kansas City Cardiomyopathy Questionnaire Overall Score [KCCQ-OS]). RESULTS Among 1,974 patients (794 surgical AVR, 1,180 transcatheter AVR), the extent of cardiac damage at baseline was associated with lower KCCQ scores both at baseline and at 1 year after AVR (P = 10 points) at 1 year (stages 0-4: 10.6% vs 19.6% vs 29.0% vs 44.7% vs 39.8%; P = 1 stage thorn 26.8 [95% CI: 24.2-29.4] vs no change thorn 21.4 [95% CI: 20.0-22.7] vs deterioration of >= 1 stage thorn 17.5 [95% CI: 15.4-19.5]; P < 0.0001). CONCLUSIONS The extent of cardiac damage before AVR has an important impact on health status outcomes, both cross-sectionally and after AVR. (PARTNER II Trial: Placement of AoRTic TraNscathetER Valves II -XT Intermediate and High Risk (PII A), NCT01314313; The PARTNER II Trial: Placement of AoRTic TraNscathetER Valves -PII B [PARTNERII B], NCT02184442; PARTNER 3 Trial: Safety and Effectiveness of the SAPIEN 3 Transcatheter Heart Valve in Low Risk Patients With Aortic Stenosis [P3], NCT02675114) (J Am Coll Cardiol 2023;81:743-752) (c) 2023 by the American College of Cardiology Foundation.Radiolog

In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization

Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers a realistic chance that this novel mechanism to inhibit afferent nerve sensitization may find its place in the sun and bring some merciful relief to the torment of persistent discomfort and pain. The development philosophy at Afferent is to conduct proof of concept patient studies and best identify target patient groups that may benefit from this new intervention