Cerebral Collateral Circulation in Carotid Artery Disease

Carotid artery disease is common and increases the risk of stroke. However, there is wide variability on the severity of clinical manifestations of carotid disease, ranging from asymptomatic to fatal stroke. The collateral circulation has been recognized as an important aspect of cerebral circulation affecting the risk of stroke as well as other features of stroke presentation, such as stroke patterns in patients with carotid artery disease. The cerebral circulation attempts to maintain constant cerebral perfusion despite changes in systemic conditions, due to its ability to autoregulate blood flow. In case that one of the major cerebral arteries is compromised by occlusive disease, the cerebral collateral circulation plays an important role in preserving cerebral perfusion through enhanced recruitment of blood flow. With the advent of techniques that allow rapid evaluation of cerebral perfusion, the collateral circulation of the brain and its effectiveness may also be evaluated, allowing for prompt assessment of patients with acute stroke due to involvement of the carotid artery, and risk stratification of patients with carotid stenosis in chronic stages. Understanding the cerebral collateral circulation provides a basis for the future development of new diagnostic tools, risk stratification, predictive models and new therapeutic modalities. In the present review we discuss basic aspects of the cerebral collateral circulation, diagnostic methods to assess collateral circulation, and implications in occlusive carotid artery disease

Climate change adaptation responses and human mobility in the Mekong Delta: local perspectives from rural households in An Giang Province, Vietnam

Abstract Climate change influences the adaptation responses and mobility patterns of smallholder farmers across multiple scales. This study employed an inductive approach to observe smallholder farmers in An Giang Province in the Vietnamese Mekong Delta to compare the effects of various environmental and climate-related stressors on households with and without contributing migrant household members and on households of different income levels in two rural communes. We looked into the roles that adaptation responses and human mobility patterns play in the daily livelihoods of (translocal) households. We adopted a mixed-methods approach, which involved the administration of a livelihood survey among households in two rural communes (N = 106) and, subsequently, two focus group discussions, unstructured in-depth interviews, and secondary data analysis. We discovered that human mobility, adaptation responses, and climate change are interwoven in a web of complex relationships. No clear differences in effects and climate adaptation responses were discovered between emigrant and nonemigrant households. Hence, paradigms that either portray migration as a failure to adapt or as a form of adaptation in the context of climate change do not adequately explain the findings of this study. Differences between income groups were, however, observed. Relative to other income groups, middle-income farmers were disproportionally affected by climate-related disasters. Additionally, out-migration, aging, upstream hydropower development, and COVID-19 lockdowns posed significant challenges to the livelihoods of smallholder farmers. The compound effects of these multiple stressors indicate that human mobility, climate change and adaptation patterns should be best approached as ‘wicked’ problems

Synergetic electrocatalytic activities towards hydrogen peroxide: Understanding the ordered structure of PdNi bimetallic nanocatalysts

Mesoporous carbon-template-supported novel-order face-centered cubic (fcc) structured bimetallic PdNi nanocatalysts were prepared for the ‘green synthesis’ of hydrogen peroxide (H2O2). Our results show that the alloy crystal structure of fcc-Pd050Ni050 can be structurally transformed into a face-centered tetragonal (fct) structure after hydrogen-assisted heat-treatment at 750 °C. Transformation of the fcc structure into the fct structure resulted in ordered intermetallically structured Pd050Ni050 alloys with higher alloying extents as confirmed by X-ray absorption spectroscopy (XAS) and high resolution TEM. In addition, an electrochemical detection method was developed for in situ measurement of direct H2O2 synthesis. The fct-Pd050Ni050 catalysts produced demonstrated both enhanced structural stability and higher productivity than the fcc structured nanocatalysts and in doing so potentially offer a cost-effective route to the direct synthesis of hydrogen peroxide. Keywords: Direct synthesis of H2O2, Face-centered tetragonal, Ordered structure, Palladium- nicke

Interplay between Molybdenum Dopant and Oxygen Vacancies in a TiO₂ Support Enhances the Oxygen Reduction Reaction

In this study, molybdenum doping of anatase TiO₂, used as a Pt catalyst support, both augments resistance against the carbon corrosion that commonly occurs in oxygen reduction reaction (ORR) Pt/C catalysts and promotes the generation of oxygen vacancies that allow better electron transfer from the nanosupport to Pt, thereby facilitating the oxygen dissociation reaction. The effects of the oxygen vacancies within the Mo-doped TiO₂ nanosupport on ORR activity and stability are investigated both experimentally and by density functional theory analysis. The mass activity of Pt-supported molybdenum-doped anatase TiO₂ is shown to be 9.1 times higher than that of a commercial standard Pt/C catalyst after hydrogen reduction. The oxide-supported nanocatalysts also show improved stability against Pt sintering under during cycling, because of strong metal–support interactions

The clinical features and genomic epidemiology of carbapenem-resistant Acinetobacter baumannii infections at a tertiary hospital in Vietnam

ABSTRACT: Objectives: To characterise the clinical features of Acinetobacter baumannii infections and investigate the phylogenetic structure and transmission dynamics of A. baumannii in Vietnam. Methods: Between 2019 and 2020, a surveillance of A. baumannii (AB) infections was conducted at a tertiary hospital in Ho Chi Minh City, Vietnam. Risk factors for in-hospital mortality were analysed using logistic regressions. Whole-genome sequence data were used to characterise genomic species, sequence types (STs), antimicrobial resistance genes, surface antigens, and phylogenetic relatedness of AB isolates. Results: Eighty-four patients with AB infections were enrolled in the study, 96% of whom were hospital-acquired. Half of the AB isolates were identified from ICU-admitted patients, while the remaining isolates were from non-ICU patients. The overall in-hospital mortality was 56%, with associated risk factors including advanced age, ICU stay, exposure to mechanical ventilation/central venous catheterization, pneumonia as source of AB infection, prior use of linezolid/aminoglycosides, and AB treatment with colistin-based therapy. Nearly 91% of isolates were carbapenem-resistant; 92% were multidrug-resistant; and 6% were colistin-resistant. ST2, ST571, and ST16 were the three dominant carbapenem-resistant A. baumannii (CRAB) genotypes, exhibiting distinct AMR gene profiles. Phylogenetic analysis of CRAB ST2 isolates together with previously published ST2 collection provided evidence of intra- and inter-hospital transmission of this clone. Conclusions: Our study highlights a high prevalence of carbapenem resistance and multidrug resistance in A. baumannii and elucidates the spread of CRAB within and between hospitals. Strengthening infection control measures and routine genomic surveillance are crucial to reducing the spread of CRAB and detecting novel pan-drug-resistant variants in a timely fashion