Cu Promoted the Dynamic Evolution of Ni-Based Catalysts for Polyethylene Terephthalate Plastic Upcycling.

Upcycling plastic wastes into value-added chemicals is a promising approach to put end-of-life plastic wastes back into their ecocycle. As one of the polyesters that is used daily, polyethylene terephthalate (PET) plastic waste is employed here as the model substrate. Herein, a nickel (Ni)-based catalyst was prepared via electrochemically depositing copper (Cu) species on Ni foam (NiCu/NF). The NiCu/NF formed Cu/CuO and Ni/NiO/Ni(OH)2 core-shell structures before electrolysis and reconstructed into NiOOH and CuOOH/Cu(OH)2 active species during the ethylene glycol (EG) oxidation. After oxidation, the Cu and Ni species evolved into more reduced species. An indirect mechanism was identified as the main EG oxidation (EGOR) mechanism. In EGOR, NiCu60s/NF catalyst exhibited an optimal Faradaic efficiency (FE, 95.8%) and yield rate (0.70 mmol cm-2 h-1) for formate production. Also, over 80% FE of formate was achieved when a commercial PET plastic powder hydrolysate was applied. Furthermore, commercial PET plastic water bottle waste was employed as a substrate for electrocatalytic upcycling, and pure terephthalic acid (TPA) was recovered only after 1 h electrolysis. Lastly, density functional theory (DFT) calculation revealed that the key role of Cu was significantly reducing the Gibbs free-energy barrier (ΔG) of EGOR's rate-determining step (RDS), promoting catalysts' dynamic evolution, and facilitating the C-C bond cleavage.

Zeta Potential and Size Analysis of Zeolitic Imidazolate Framework-8 Nanocrystals Prepared by Surfactant-Assisted Synthesis.

The crystal nucleation and growth mechanism of monodispersed metal-organic framework nanoparticles were studied using time-resolved light dynamic, electrokinetic, and powder X-ray diffraction methods. We confirmed that zeolitic imidazolate framework-8 (ZIF-8) nanocrystals follow a nonclassical crystal growth pathway, where a fast nucleation occurs with dense liquid clusters or nanocrystals forming spontaneously when two precursors are mixed. We also explored the zeta potential and solvodynamic size changes of ZIF-8 prepared by a surfactant-assisted synthesis. Three modulators, including 1-methylimidazole (1-mIm), tris(hydroxymethyl)aminomethane (THAM), and (1-hexadecyl)trimethylammonium bromide (CTAB), were studied. We found that 1-mIm dramatically increases the rate of nucleation of ZIF-8. With an increasing amount of 1-mIm, which functions as a coordination modulator, the size increases, and the zeta potential of ZIF-8 decreases. Whereas THAM, as both a coordination and a deprotonation modulator, increases the size and zeta potential of ZIF-8 simultaneously, CTAB, as a long alkyl cationic surfactant, mainly adsorbs on the surface of ZIF-8, and the zeta potential of the formed ZIF-8 is controlled by the amount of CTAB in solution compared with its critical micelle concentration. Overall, we reveal that the modulator type and concentration can be used to control the size and zeta potential of the dispersed ZIF-8 nanocrystals in a colloid system. The experiments also enable identification of the nucleation and crystal growth processes of ZIF-8. The findings will be applicable to other nanocrystals in colloid systems, which are used for heterogeneous catalysis and guest molecular loadings.

pH-Responsive Metal-Organic Framework Thin Film for Drug Delivery.

In this work, surface-supportive MIL-88B(Fe) was explored as a pH-stimuli thin film to release ibuprofen as a model drug. We used surface plasmon resonance microscopy to study the pH-responsive behaviors of MIL-88B(Fe) film in real time. A dissociation constant of (6.10 ± 0.86) × 10-3 s-1 was measured for the MIL-88B(Fe) film in an acidic condition (pH 6.3), which is about 10 times higher than the dissociation of the same film in a neutral pH condition. MIL-88B(Fe) films are also capable of loading around 6.0 µg/cm2 of ibuprofen, which was measured using a quartz crystal microbalance (QCM). Drug release profiles were compared in both acidic and neutral pH conditions (pH 6.3 and 7.4) using a QCM cell to model the drug release in healthy body systems and those containing inflammatory tissues or cancerous tumors. It was found that the amount of drug released in acidic environments had been significantly higher compared to that in a neutral system within 55 h of testing time. The pH-sensitive chemical bond breaking between Fe3+ and the carboxylate ligands is the leading cause of drug release in acidic conditions. This work exhibits the potential of using MOF thin films as pH-triggered drug delivery systems.

The Unmasking Effect: Propofol-Induced Brugada Pattern in a Critically Ill Patient.

Brugada syndrome is a known cause of dysrhythmias and sudden cardiac death. It is linked to mutations in myocardial sodium channel leading to hyperexcitable cardiac myocytes. The use of this sedative has been linked to the development of inducible Brugada via blockade of sodium currents in cardiac myocytes. Although propofol is usually avoided in patients with known Brugada syndrome, some patients might have undiagnosed Brugada syndrome and thus are at risk for complications. We present a case of propofol induced Brugada in a critically ill patient.

Management of Heparin-Induced Thrombocytopenia Using Plasmapharesis in Patients Undergoing HeartMate 3 Left Ventricular Assist Device.

Heparin-induced thrombocytopenia (HIT) type-2 is a rare, but life-threatening complication that presents a unique challenge in patients undergoing cardiac surgery. Patients that require cardiac surgery with HIT present a dilemma between intraoperative anticoagulation, perioperative bleeding risk, and perioperative thrombotic events. We describe a case series of four patients who developed HIT in their hospital course before HeartMate 3 (HM3) left ventricular assist device implantation. Following a multidisciplinary approach, all patients did well intraoperatively with an approach of preoperative plasmapheresis, intraoperative unfractionated heparin (UFH), and postoperative conversion to bivalirudin with a bridge to warfarin. However, two patients had postoperative bleeding complications on bivalirudin. This case series details the therapeutic challenges encountered for HM3 implantation in patients with HIT and offers a therapeutic alternative to intraoperative bivalirudin in the effort to decrease perioperative complications in this challenging patient population.

Detecting early onset of anthracyclines-induced cardiotoxicity using a novel panel of biomarkers in West-Virginian population with breast cancer.

Cardiotoxic manifestation associated with breast cancer treatment by anthracycline regimen increases patients' susceptibility to myocardial injury, reduction in left ventricular ejection fraction and complications associated with heart failure. There is currently no standardized, minimally invasive, cost effective and clinically verified procedure to monitor cardiotoxicity post-anthracycline therapy initiation, and to detect early onset of irreversible cardiovascular complications. This study aims to create a panel of novel biomarkers and circulating miRNAs associated with cardiotoxicity, further assessing their correlation with cardiac injury specific markers, troponin I and T, and demonstrate the development of cardiac dysfunction in breast cancer patients. Blood obtained from West Virginian females clinically diagnosed with breast cancer and receiving anthracyclines showed upregulated level of biomarkers and circulating miRNAs after 3 and 6 months of chemotherapy initiation with increased levels of cardiac troponin I and T. These biomarkers and miRNAs significantly correlated with elevated troponins. Following 6 months of anthracycline-regimens, 23% of the patient population showed cardiotoxicity with reduced left ventricular ejection fraction. Our results support the clinical application of plasma biomarkers and circulating miRNAs to develop a panel for early diagnosis of chemotherapy related cardiac dysfunction which will enable early detection of disease progression and management of irreversible cardiac damage.

The Destabilized Artery: A Case of Spontaneous Coronary Artery Dissection Presenting as Unstable Angina.

Spontaneous coronary artery dissection (SCAD) is increasingly being recognized as a cause of acute coronary syndrome (ACS). This increased recognition of SCAD has been noted in patients with and without traditional cardiovascular risk factors such as diabetes mellitus, hyperlipidemia, and cigarette smoking. The increasing incidence is believed to be due to recent advances in diagnostic and coronary imaging modalities. The most common presenting feature is chest pain or discomfort. Normal troponin level does not rule out SCAD as the definitive diagnosis is made on coronary angiography. Percutaneous intervention (PCI) for SCAD has been associated with lower success rates compared to PCI for atherosclerotic coronary artery disease. Medical management is, therefore, the initial treatment of choice.

Okazaki fragment processing-independent role for human Dna2 enzyme during DNA replication.

Dna2 is an essential helicase/nuclease that is postulated to cleave long DNA flaps that escape FEN1 activity during Okazaki fragment (OF) maturation in yeast. We previously demonstrated that the human Dna2 orthologue (hDna2) localizes to the nucleus and contributes to genomic stability. Here we investigated the role hDna2 plays in DNA replication. We show that Dna2 associates with the replisome protein And-1 in a cell cycle-dependent manner. Depletion of hDna2 resulted in S/G(2) phase-specific DNA damage as evidenced by increased γ-H2AX, replication protein A foci, and Chk1 kinase phosphorylation, a readout for activation of the ATR-mediated S phase checkpoint. In addition, we observed reduced origin firing in hDna2-depleted cells consistent with Chk1 activation. We next examined the impact of hDna2 on OF maturation and replication fork progression in human cells. As expected, FEN1 depletion led to a significant reduction in OF maturation. Strikingly, the reduction in OF maturation had no impact on replication fork progression, indicating that fork movement is not tightly coupled to lagging strand maturation. Analysis of hDna2-depleted cells failed to reveal a defect in OF maturation or replication fork progression. Prior work in yeast demonstrated that ectopic expression of FEN1 rescues Dna2 defects. In contrast, we found that FEN1 expression in hDna2-depleted cells failed to rescue genomic instability. These findings suggest that the genomic instability observed in hDna2-depleted cells does not arise from defective OF maturation and that hDna2 plays a role in DNA replication that is distinct from FEN1 and OF maturation.

FEN1 ensures telomere stability by facilitating replication fork re-initiation.

Telomeres are terminal repetitive DNA sequences whose stability requires the coordinated actions of telomere-binding proteins and the DNA replication and repair machinery. Recently, we demonstrated that the DNA replication and repair protein Flap endonuclease 1 (FEN1) is required for replication of lagging strand telomeres. Here, we demonstrate for the first time that FEN1 is required for efficient re-initiation of stalled replication forks. At the telomere, we find that FEN1 depletion results in replicative stress as evidenced by fragile telomere expression and sister telomere loss. We show that FEN1 participation in Okazaki fragment processing is not required for efficient telomere replication. Instead we find that FEN1 gap endonuclease activity, which processes DNA structures resembling stalled replication forks, and the FEN1 interaction with the RecQ helicases are vital for telomere stability. Finally, we find that FEN1 depletion neither impacts cell cycle progression nor in vitro DNA replication through non-telomeric sequences. Our finding that FEN1 is required for efficient replication fork re-initiation strongly suggests that the fragile telomere expression and sister telomere losses observed upon FEN1 depletion are the direct result of replication fork collapse. Together, these findings suggest that other nucleases compensate for FEN1 loss throughout the genome during DNA replication but fail to do so at the telomere. We propose that FEN1 maintains stable telomeres by facilitating replication through the G-rich lagging strand telomere, thereby ensuring high fidelity telomere replication.

Human Dna2 is a nuclear and mitochondrial DNA maintenance protein.

Dna2 is a highly conserved helicase/nuclease that in yeast participates in Okazaki fragment processing, DNA repair, and telomere maintenance. Here, we investigated the biological function of human Dna2 (hDna2). Immunofluorescence and biochemical fractionation studies demonstrated that hDna2 was present in both the nucleus and the mitochondria. Analysis of mitochondrial hDna2 revealed that it colocalized with a subfraction of DNA-containing mitochondrial nucleoids in unperturbed cells. Upon the expression of disease-associated mutant forms of the mitochondrial Twinkle helicase which induce DNA replication pausing/stalling, hDna2 accumulated within nucleoids. RNA interference-mediated depletion of hDna2 led to a modest decrease in mitochondrial DNA replication intermediates and inefficient repair of damaged mitochondrial DNA. Importantly, hDna2 depletion also resulted in the appearance of aneuploid cells and the formation of internuclear chromatin bridges, indicating that nuclear hDna2 plays a role in genomic DNA stability. Together, our data indicate that hDna2 is similar to its yeast counterpart and is a new addition to the growing list of proteins that participate in both nuclear and mitochondrial DNA maintenance.