Hybrid Molecular Beam Epitaxy for Single-Crystalline Oxide Membranes with Binary Oxide Sacrificial Layers.

The advancement in thin-film exfoliation for synthesizing oxide membranes has led to possibilities for creating artificially assembled heterostructures with structurally and chemically incompatible materials. The sacrificial layer method is a promising approach to exfoliate as-grown films from a compatible material system, allowing for their integration with dissimilar materials. Nonetheless, the conventional sacrificial layers often possess an intricate stoichiometry, thereby constraining their practicality and adaptability, particularly when considering techniques such as molecular beam epitaxy (MBE). This is where easy-to-grow binary alkaline-earth-metal oxides with a rock salt crystal structure are useful. These oxides, which include (Mg, Ca, Sr, Ba)O, can be used as a sacrificial layer covering a much broader range of lattice parameters compared to conventional sacrificial layers and are easily dissolvable in deionized water. In this study, we show the epitaxial growth of the single-crystalline perovskite SrTiO3 (STO) on sacrificial layers consisting of crystalline SrO, BaO, and Ba1-xCaxO films, employing a hybrid MBE method. Our results highlight the rapid (≤5 min) dissolution of the sacrificial layer when immersed in deionized water, facilitating the fabrication of millimeter-sized STO membranes. Using high-resolution X-ray diffraction, atomic-force microscopy, scanning transmission electron microscopy, impedance spectroscopy, and scattering-type near-field optical microscopy (SNOM), we demonstrate single-crystalline STO membranes with bulk-like intrinsic dielectric properties. The employment of alkaline earth metal oxides as sacrificial layers is likely to simplify membrane synthesis, particularly with MBE, thus expanding the research and application possibilities.

Protocol for the WARM Hearts study: examining cardiovascular disease risk in middle-aged and older women - a prospective, observational cohort study.

INTRODUCTION: Cardiovascular disease (CVD) is a leading cause of death in women. Novel approaches to detect early signs of elevated CVD risk in women are needed. Enhancement of traditional CVD risk assessment approaches through the addition of procedures to assess physical function or frailty as well as novel biomarkers of cardiovascular, gut and muscle health could improve early identification. The Women's Advanced Risk-assessment in Manitoba (WARM) Hearts study will examine the use of novel non-invasive assessments and biomarkers to identify women who are at elevated risk for adverse cardiovascular events. METHODS AND ANALYSIS: One thousand women 55 years of age or older will be recruited and screened by the WARM Hearts observational, cohort study. The two screening appointments will include assessments of medical history, gender variables, body composition, cognition, frailty status, functional fitness, physical activity levels, nutritional status, quality of life questionnaires, sleep behaviour, resting blood pressure (BP), BP response to moderate-intensity exercise, a non-invasive measure of arterial stiffness and heart rate variability. Blood sample analysis will be used to assess lipid and novel biomarker profiles and stool samples will support the characterisation of gut microbiota. The incidence of the adverse cardiovascular outcomes will be assessed 5 years after screening to compare WARM Hearts approaches to the Framingham Risk Score, the current clinical standard of assessing CVD risk in Canada. ETHICS AND DISSEMINATION: The University of Manitoba Health Research Ethics Board (7 October 2019) and the St Boniface Hospital Research Review Committee (7 October 2019) approved the trial (Ethics Number HS22576 (H2019:063)). Recruitment started 10 October 2020. Data gathered from the WARM Hearts study will be published in peer-reviewed journals and presented at national and international conferences. Knowledge translation strategies will be created to share our findings with stakeholders who are positioned to implement evidence-informed CVD risk assessment programming. TRIAL REGISTRATION NUMBER: NCT03938155.

Elimination of rNMPs from mitochondrial DNA has no effect on its stability.

Ribonucleotides (rNMPs) incorporated in the nuclear genome are a well-established threat to genome stability and can result in DNA strand breaks when not removed in a timely manner. However, the presence of a certain level of rNMPs is tolerated in mitochondrial DNA (mtDNA) although aberrant mtDNA rNMP content has been identified in disease models. We investigated the effect of incorporated rNMPs on mtDNA stability over the mouse life span and found that the mtDNA rNMP content increased during early life. The rNMP content of mtDNA varied greatly across different tissues and was defined by the rNTP/dNTP ratio of the tissue. Accordingly, mtDNA rNMPs were nearly absent in SAMHD1-/- mice that have increased dNTP pools. The near absence of rNMPs did not, however, appreciably affect mtDNA copy number or the levels of mtDNA molecules with deletions or strand breaks in aged animals near the end of their life span. The physiological rNMP load therefore does not contribute to the progressive loss of mtDNA quality that occurs as mice age.

DNA polymerase η contributes to genome-wide lagging strand synthesis.

DNA polymerase η (pol η) is best known for its ability to bypass UV-induced thymine-thymine (T-T) dimers and other bulky DNA lesions, but pol η also has other cellular roles. Here, we present evidence that pol η competes with DNA polymerases α and δ for the synthesis of the lagging strand genome-wide, where it also shows a preference for T-T in the DNA template. Moreover, we found that the C-terminus of pol η, which contains a PCNA-Interacting Protein motif is required for pol η to function in lagging strand synthesis. Finally, we provide evidence that a pol η dependent signature is also found to be lagging strand specific in patients with skin cancer. Taken together, these findings provide insight into the physiological role of DNA synthesis by pol η and have implications for our understanding of how our genome is replicated to avoid mutagenesis, genome instability and cancer.

Harnessing the RNA interference pathway to advance treatment and prevention of hepatocellular carcinoma.

Primary liver cancer is the fifth most common malignancy in the world and is a leading cause of cancer-related mortality. Available treatment for hepatocellular carcinoma (HCC), the commonest primary liver cancer, is rarely curative and there is a need to develop therapy that is more effective. Specific and powerful gene silencing that can be achieved by activating RNA interference (RNAi) has generated enthusiasm for exploiting this pathway for HCC therapy. Many studies have been carried out with the aim of silencing HCC-related cellular oncogenes or the hepatocarcinogenic hepatitis B virus (HBV) and hepatitis C virus (HCV). Proof of principle studies have demonstrated promising results, and an early clinical trial assessing RNAi-based HBV therapy is currently in progress. Although the data augur well, there are several significant hurdles that need to be overcome before the goal of RNAi-based therapy for HCC is realized. Particularly important are the efficient and safe delivery of RNAi effecters to target malignant tissue and the limitation of unintended harmful non-specific effects.

Biohydrogen production by Enterobacter cloacae and Citrobacter freundii in carrier induced granules.

Carrier induced granular particles comprising Enterobacter cloacae and Citrobacter freundii were used to generate H(2) from sucrose in an anaerobic fluidized bed bioreactor. At a hydraulic retention time of 4.5 h, 95.8% of the sucrose was consumed and the rate of H(2) production reached 180 mmol H(2) l h(-1). Biogas composition for H(2) and CO(2) was 42 and 55%, respectively.