Early deficits in an in vitro striatal microcircuit model carrying the Parkinson's GBA-N370S mutation.

Understanding medium spiny neuron (MSN) physiology is essential to understand motor impairments in Parkinson's disease (PD) given the architecture of the basal ganglia. Here, we developed a custom three-chambered microfluidic platform and established a cortico-striato-nigral microcircuit partially recapitulating the striatal presynaptic landscape in vitro using induced pluripotent stem cell (iPSC)-derived neurons. We found that, cortical glutamatergic projections facilitated MSN synaptic activity, and dopaminergic transmission enhanced maturation of MSNs in vitro. Replacement of wild-type iPSC-derived dopamine neurons (iPSC-DaNs) in the striatal microcircuit with those carrying the PD-related GBA-N370S mutation led to a depolarisation of resting membrane potential and an increase in rheobase in iPSC-MSNs, as well as a reduction in both voltage-gated sodium and potassium currents. Such deficits were resolved in late microcircuit cultures, and could be reversed in younger cultures with antagonism of protein kinase A activity in iPSC-MSNs. Taken together, our results highlight the unique utility of modelling striatal neurons in a modular physiological circuit to reveal mechanistic insights into GBA1 mutations in PD.

Tau depletion in human neurons mitigates Aß-driven toxicity.

Alzheimer's disease (AD) is an age-related neurodegenerative condition and the most common type of dementia, characterised by pathological accumulation of extracellular plaques and intracellular neurofibrillary tangles that mainly consist of amyloid-ß (Aß) and hyperphosphorylated tau aggregates, respectively. Previous studies in mouse models with a targeted knock-out of the microtubule-associated protein tau (Mapt) gene demonstrated that Aß-driven toxicity is tau-dependent. However, human cellular models with chronic tau lowering remain unexplored. In this study, we generated stable tau-depleted human induced pluripotent stem cell (iPSC) isogenic panels from two healthy individuals using CRISPR-Cas9 technology. We then differentiated these iPSCs into cortical neurons in vitro in co-culture with primary rat cortical astrocytes before conducting electrophysiological and imaging experiments for a wide range of disease-relevant phenotypes. Both AD brain derived and recombinant Aß were used in this study to elicit toxic responses from the iPSC-derived cortical neurons. We showed that tau depletion in human iPSC-derived cortical neurons caused considerable reductions in neuronal activity without affecting synaptic density. We also observed neurite outgrowth impairments in two of the tau-depleted lines used. Finally, tau depletion protected neurons from adverse effects by mitigating the impact of exogenous Aß-induced hyperactivity, deficits in retrograde axonal transport of mitochondria, and neurodegeneration. Our study established stable human iPSC isogenic panels with chronic tau depletion from two healthy individuals. Cortical neurons derived from these iPSC lines showed that tau is essential in Aß-driven hyperactivity, axonal transport deficits, and neurodegeneration, consistent with studies conducted in Mapt-/- mouse models. These findings highlight the protective effects of chronic tau lowering strategies in AD pathogenesis and reinforce the potential in clinical settings. The tau-depleted human iPSC models can now be applied at scale to investigate the involvement of tau in disease-relevant pathways and cell types.

Recent Advances in Adenosine-to-Inosine RNA Editing in Cancer.

RNA epigenetics, or epitranscriptome, is a growing group of RNA modifications historically classified into two categories: RNA editing and RNA modification. RNA editing is usually understood as post-transcriptional RNA processing (except capping, splicing and polyadenylation) that changes the RNA nucleotide sequence encoded by the genome. This processing can be achieved through the insertion or deletion of nucleotides or deamination of nucleobases, generating either standard nucleotides such as uridine (U) or the rare nucleotide inosine (I). Adenosine-to-inosine (A-to-I) RNA editing is the most prevalent type of RNA modification in mammals and is catalyzed by adenosine deaminase acting on the RNA (ADAR) family of enzymes that recognize double-stranded RNAs (dsRNAs). Inosine mimics guanosine (G) in base pairing with cytidine (C), thereby A-to-I RNA editing alters dsRNA secondary structure. Inosine is also recognized as guanosine by the splicing and translation machineries, resulting in mRNA alternative splicing and protein recoding. Therefore, A-to-I RNA editing is an important mechanism that causes and regulates "RNA mutations" in both normal physiology and diseases including cancer. In this chapter, we reviewed current paradigms and developments in the field of A-to-I RNA editing in the context of cancer.

In-Situ-Grown Cu Dendrites Plasmonically Enhance Electrocatalytic Hydrogen Evolution on Facet-Engineered Cu2 O.

Herein, facet-engineered Cu2 O nanostructures are synthesized by wet chemical methods for electrocatalytic HER, and it is found that the octahedral Cu2 O nanostructures with exposed crystal planes of (111) (O-Cu2 O) has the best hydrogen evolution performance. Operando Raman spectroscopy and ex-situ characterization techniques showed that Cu2 O is reduced during HER, in which Cu dendrites are grown on the surface of the Cu2 O nanostructures, resulting in the better HER performance of O-Cu2 O after HER (O-Cu2 O-A) compared with that of the as-prepared O-Cu2 O. Under illumination, the onset potential of O-Cu2 O-A is ca. 52 mV positive than that of O-Cu2 O, which is induced by the plasmon-activated electrochemical system consisting of Cu2 O and the in-situ generated Cu dendrites. Incident photon-to-current efficiency (IPCE) measurements and the simulated UV-Vis spectrum demonstrate the hot electron injection (HEI) from Cu dendrites to Cu2 O. Ab initio nonadiabatic molecular dynamics (NAMD) simulations revealed the transfer of photogenerated electrons (27 fs) from Cu dendrites to Cu2 O nanostructures is faster than electron relaxation (170 fs), enhancing its surface plasmons activity, and the HEI of Cu dendrites increases the charge density of Cu2 O. These make the energy level of the catalyst be closer to that of H+ /H2 , evidenced by the plasmon-enhanced HER electrocatalytic activity.

Photo-Induced Active Lewis Acid-Base Pairs in a Metal-Organic Framework for H2 Activation.

The establishment of active sites as the frustrated Lewis pair (FLP) has recently attracted much attention ranging from homogeneous to heterogeneous systems in the field of catalysis. Their unquenched reactivity of Lewis acid and base pairs in close proximity that are unable to form stable adducts has been shown to activate small molecules such as dihydrogen heterolytically. Herein, we show that grafted Ru metal-organic framework-based catalysts prepared via N-containing linkers are rather catalytically inactive for H2 activation despite the application of elevated temperatures. However, upon light illumination, charge polarization of the anchored Ru bipyridine complex can form a transient Lewis acid-base pair, Ru+-N- via metal-to-ligand charge transfer, as confirmed by time-dependent density functional theory (TDDFT) calculations to carry out effective H2-D2 exchange. FTIR and 2-D NMR endorse the formation of such reactive intermediate(s) upon light irradiation.

Calcium dysregulation combined with mitochondrial failure and electrophysiological maturity converge in Parkinson's iPSC-dopamine neurons.

Parkinson's disease (PD) is characterized by a progressive deterioration of motor and cognitive functions. Although death of dopamine neurons is the hallmark pathology of PD, this is a late-stage disease process preceded by neuronal dysfunction. Here we describe early physiological perturbations in patient-derived induced pluripotent stem cell (iPSC)-dopamine neurons carrying the GBA-N370S mutation, a strong genetic risk factor for PD. GBA-N370S iPSC-dopamine neurons show an early and persistent calcium dysregulation notably at the mitochondria, followed by reduced mitochondrial membrane potential and oxygen consumption rate, indicating mitochondrial failure. With increased neuronal maturity, we observed decreased synaptic function in PD iPSC-dopamine neurons, consistent with the requirement for ATP and calcium to support the increase in electrophysiological activity over time. Our work demonstrates that calcium dyshomeostasis and mitochondrial failure impair the higher electrophysiological activity of mature neurons and may underlie the vulnerability of dopamine neurons in PD.

Confined Ru Sites in a 13X Zeolite for Ultrahigh H2 Production from NH3 Decomposition.

Catalytic NH3 synthesis and decomposition offer a new promising way to store and transport renewable energy in the form of NH3 from remote or offshore sites to industrial plants. To use NH3 as a hydrogen carrier, it is important to understand the catalytic functionality of NH3 decomposition reactions at an atomic level. Here, we report for the first time that Ru species confined in a 13X zeolite cavity display the highest specific catalytic activity of over 4000 h-1 for the NH3 decomposition with a lower activation barrier, compared to most reported catalytic materials in the literature. Mechanistic and modeling studies clearly indicate that the N-H bond of NH3 is ruptured heterolytically by the frustrated Lewis pair of Ruδ+-Oδ- in the zeolite identified by synchrotron X-rays and neutron powder diffraction with Rietveld refinement as well as other characterization techniques including solid-state nuclear magnetic resonance spectroscopy, in situ diffuse reflectance infrared transform spectroscopy, and temperature-programmed analysis. This contrasts with the homolytic cleavage of N-H displayed by metal nanoparticles. Our work reveals the unprecedented unique behavior of cooperative frustrated Lewis pairs created by the metal species on the internal zeolite surface, resulting in a dynamic hydrogen shuttling from NH3 to regenerate framework Brønsted acid sites that eventually are converted to molecular hydrogen.

Metal-loaded zeolites in ammonia decomposition catalysis.

The viability of using ammonia as a hydrogen storage vector is contingent on the development of catalytic systems active for ammonia decomposition at low temperatures. Zeolite-supported metal catalysts, unlike systems based on supports like MgO or carbon nanotubes (CNTs), are crystalline and lend themselves to analytic techniques like synchrotron X-ray powder diffraction (SXRD) and Rietveld refinement, allowing precise characterisation of catalytic active sites, and therefore mechanistic elucidation. This study focuses on characterising and optimising novel zeolite-supported Ru catalysts for ammonia decomposition, with a focus on the effects of N-substitution on catalyst structure and activity. Characterisation focuses on an unsubstituted and N-substituted Ru-zeolite Y pair with NMR, FTIR, TEM, XRD, XAS, ICP, and BET, demonstrating the successful incorporation of N into the zeolite framework and an enhancement in metal dispersion upon N-substitution. A series of 18 monometallic and bimetallic catalysts is then synthesised on X and USY supports and screened for catalytic activity. Ru is identified as the most active metal for ammonia decomposition. Observed trends suggest catalyst dispersion can be increased with substantially lower metal loadings, and in particular via the formation of stably anchored oligonuclear metal clusters within the zeolite framework, as opposed to much larger nanoparticles (NPs) on its exterior, following N-substitution of the framework. DFT modelling proposes a prismatic Ru6N6 cluster fitted to XAS data. High-activity catalyst Ru-ß (N) 2.4% demonstrates comparable or better ammonia conversion by Ru wt% than recently reported catalysts in the literature at 450 °C and 30 000 WHSV.

Developing a quality improvement project to tackle the desflurane problem.

Anaesthesia is associated with the routine use of volatile anaesthetic agents, all of which are potent greenhouse gases in varying degrees. Desflurane, in particular, has a high global warming potential and in recent years, there has been a global movement to reduce or remove its usage entirely from operating theatres. We work in a large tertiary teaching hospital in Singapore with deeply entrenched practices of using desflurane to facilitate high turnover of operating theatre cases. We launched a quality improvement project to (1) reduce the median usage of desflurane by 50% (by volume), and (2) reduce the number of theatre cases administering desflurane by 50% over a period of 6 months.We collected baseline data to determine departmental monthly median usage of desflurane. We then deployed sequential quality improvement methods to educate staff and to eliminate misconceptions, as well as to promote a gradual cultural change.We successfully reduced monthly median desflurane usage from 31.5 L to 12.2 L per month (61.3% reduction) within our targeted time frame. We also achieved a reduction in the number of theatre cases using desflurane by approximately 80%. This translated to significant cost savings of US$195 000 per year and over 840 tonnes of carbon dioxide equivalents saved.Healthcare is a resource intensive industry. Anaesthetists are well placed to play an important role in reducing healthcare-related carbon emissions by choosing anaesthetic techniques and resources responsibly. Through multiple Plan-Do-Study-Act cycles and a persistent, multifaceted campaign, we achieved a sustained change in our institution.

Neurons derived from individual early Alzheimer's disease patients reflect their clinical vulnerability.

Establishing preclinical models of Alzheimer's disease that predict clinical outcomes remains a critically important, yet to date not fully realized, goal. Models derived from human cells offer considerable advantages over non-human models, including the potential to reflect some of the inter-individual differences that are apparent in patients. Here we report an approach using induced pluripotent stem cell-derived cortical neurons from people with early symptomatic Alzheimer's disease where we sought a match between individual disease characteristics in the cells with analogous characteristics in the people from whom they were derived. We show that the response to amyloid-ß burden in life, as measured by cognitive decline and brain activity levels, varies between individuals and this vulnerability rating correlates with the individual cellular vulnerability to extrinsic amyloid-ß in vitro as measured by synapse loss and function. Our findings indicate that patient-induced pluripotent stem cell-derived cortical neurons not only present key aspects of Alzheimer's disease pathology but also reflect key aspects of the clinical phenotypes of the same patients. Cellular models that reflect an individual's in-life clinical vulnerability thus represent a tractable method of Alzheimer's disease modelling using clinical data in combination with cellular phenotypes.

Strategy for Safe Bronchoscopy During the COVID-19 Pandemic.

Aerosol-generating procedures are avoided for patients with coronavirus disease 2019 (COVID-19) to lower the risk of transmission to health care providers. However, when bronchoscopy is indicated, it remains unclear whether the procedure performed while the patient is under general anesthesia leads to contamination of the surroundings and whether standard endoscopy reprocessing methods are effective in eradicating severe acute respiratory syndrome coronavirus 2. This report describes a case of bronchoscopic retrieval of a foreign body in the airway of a patient under general anesthesia who tested positive for COVID-19. The report focuses on anesthesia techniques to minimize aerosolization.

Prevention of docetaxel-associated febrile neutropenia with primary granulocyte colony-stimulating factor in Chinese metastatic hormone-sensitive and castration-resistant prostate cancer patients.

INTRODUCTION: Asian prostate cancer (PC) patients are particularly susceptible to docetaxel-related febrile neutropenia (FN). We evaluated primary granulocyte colony-stimulating factor (GCSF) for preventing FN in Chinese patients with metastatic hormone-sensitive PC (mHSPC) and castration-resistant PC (mCRPC). PATIENTS AND METHODS: Data from two cohorts of 377 Chinese patients with mHSPC (100; 26.5%) and mCRPC (277; 73.5%) treated with docetaxel at six public oncology centres were analysed with multivariate regression. Primary GCSF prophylaxis was defined as administration within 5 days of starting docetaxel. The primary outcome was FN within 21 days of the first docetaxel cycle (1st FN). RESULTS: Primary GCSF was given to 71 (18.8%) patients. FN occurred in 61 patients (16.2%) including 37 (9.8%) during the first cycle. Among patients who developed 1st cycle FN (n = 37) or not (n = 340), 2 and 69 received primary GCSF (5.4 vs. 20.3%, P = .03). Primary GCSF was associated with an overall reduced risk of 1st cycle FN (odds ratio [OR] = 0.22; 95% confidence interval [CI]: 0.05-0.96, P = .04), and similar trends were observed in the mHSPC (OR = 0.36, P = .35) and mCRPC (OR = 0.16, P = .08) subgroups. Poor Eastern Cooperative Oncology Group performance status (>1) was associated with an increased risk of 1st FN (OR = 3.90; 95% CI: 1.66-9.13, P = .002). CONCLUSIONS: To alleviate the risk of docetaxel-related FN, primary GCSF prophylaxis is suggested for Asian mCRPC and mHSPC patients, particularly those with poor performance status.

Recent Advances in the Engineering of Single-Atom Catalysts Through Metal-Organic Frameworks.

This mini-review highlights some recent progress in the engineering of single-atom catalysts (SACs) through metal-organic frameworks (MOFs) and derivatives. The inherent molecular and chemical specificities within the MOFs and derivatives can offer stabilisation of the SACs with high atomic isolation and dispersion. As MOFs are often considered an infinite array of self-assembled molecular catalysts, specifically designed structures can provide further functionalities to suit the needs of different catalytic applications. In brief, we can divide the preparation approaches into three main categories: (1) fabrication onto functional groups of the ligands, (2) fabrication onto Lewis acid sites of nodal centres, and (3) synthesis via a pyrolysis-mediated technique. Through these approaches, strong metal-support interactions can be established to aid the fine-tuning of the catalytic properties. We also discuss how recent progress in the development of state-of-the-art microscopic, spectroscopic, and crystallographic techniques has enabled scientists to elucidate the structure-activity relationship.

A novel hospital capacity versus clinical justification triage score (CCTS) for prioritization of spinal surgeries in the "new normal state" of the COVID-19 pandemic.

INTRODUCTION: During the Coronavirus disease 2019 outbreak, while healthcare systems and hospitals are diverting their resources to combat the pandemic, patients who require spinal surgeries continue to accumulate. The aim of this study is to describe a novel hospital capacity versus clinical justification triage score (CCTS) to prioritize patients who require surgery during the "new normal state" of the COVID-19 pandemic. METHODOLOGY: A consensus study using the Delphi technique was carried out among clinicians from the Orthopaedic Surgery, Neurosurgery, and Anaesthesia departments. Three rounds of consensus were carried out via survey and Webinar discussions. RESULTS: A 50-points score system consisting of 4 domains with 4 subdomains was formed. The CCTS were categorized into the hospital capacity, patient factors, disease severity, and surgery complexity domains. A score between 30 and 50 points indicated that the proposed operation should proceed without delay. A score of less than 20 indicates that the proposed operation should be postponed. A score between 20 and 29 indicates that the surgery falls within a grey area where further discussion should be undertaken to make a joint justification for approval of surgery. CONCLUSION: This study is a proof of concept for the novel CCTS scoring system to prioritize surgeries to meet the rapidly changing demands of the COVID-19 pandemic. It offers a simple and objective method to stratify patients who require surgery and allows these complex and difficult decisions to be unbiased and made transparently among surgeons and hospital administrators.

Controlled synthesis of Bi- and tri-nuclear Cu-oxo nanoclusters on metal-organic frameworks and the structure-reactivity correlations.

Precisely tuning the nuclearity of supported metal nanoclusters is pivotal for designing more superior catalytic systems, but it remains practically challenging. By utilising the chemical and molecular specificity of UiO-66-NH2 (a Zr-based metal-organic framework), we report the controlled synthesis of supported bi- and trinuclear Cu-oxo nanoclusters on the Zr6O4 nodal centres of UiO-66-NH2. We revealed the interplay between the surface structures of the active sites, adsorption configurations, catalytic reactivities and associated reaction energetics of structurally related Cu-based 'single atoms' and bi- and trinuclear species over our model photocatalytic formic acid reforming reaction. This work will offer practical insight that fills the critical knowledge gap in the design and engineering of new-generation atomic and nanocluster catalysts. The precise control of the structure and surface sensitivities is important as it can effectively lead to more reactive and selective catalytic systems. The supported bi- and trinuclear Cu-oxo nanoclusters exhibit notably different catalytic properties compared with the mononuclear 'Cu1' analogue, which provides critical insight for the engineering of more superior catalytic systems.

SARS-CoV-2 in migrant worker dormitories: Geospatial epidemiology supporting outbreak management.

BACKGROUND: Migrant worker dormitories-residential complexes where 10-24 workers share living spaces-account for the majority of cases of SARS-CoV-2 infection in Singapore. To prevent overspill of transmission to the wider population, starting in early April 2020, residents were confined to their dormitories while measures were put in place to arrest the spread of infection. This descriptive study presents epidemiological data for a population of more than 60 000 migrant workers living in two barracks-style and four apartment-style dormitories located in western Singapore from April 3 to June 10, 2020. METHODS: Our report draws from data obtained over the first 50 days of outbreak management in order to describe SARS-CoV-2 transmission in high-density housing environments. Cumulative counts of SARS-CoV-2 cases and numbers of housing units affected were analyzed to report the harmonic means of harmonic means of doubling times and their 95% confidence intervals (CI). RESULTS: Multiple transmission peaks were identified involving at least 5467 cases of SARS-CoV-2 infection across six dormitories. Our geospatial heat maps gave an early indication of outbreak severity in affected buildings. We found that the number of cases of SARS-CoV-2 infection doubled every 1.56 days (95% CI 1.29-1.96) in barracks-style buildings. The corresponding doubling time for apartment-style buildings was 2.65 days (95% CI 2.01-3.87). CONCLUSIONS: Geospatial epidemiology was useful in shaping outbreak management strategies in dormitories. Our results indicate that building design plays an integral role in transmission and should be considered in the prevention of future outbreaks.

pS421 huntingtin modulates mitochondrial phenotypes and confers neuroprotection in an HD hiPSC model.

Huntington disease (HD) is a hereditary neurodegenerative disorder caused by mutant huntingtin (mHTT). Phosphorylation at serine-421 (pS421) of mHTT has been shown to be neuroprotective in cellular and rodent models. However, the genetic context of these models differs from that of HD patients. Here we employed human pluripotent stem cells (hiPSCs), which express endogenous full-length mHTT. Using genome editing, we generated isogenic hiPSC lines in which the S421 site in mHTT has been mutated into a phospho-mimetic aspartic acid (S421D) or phospho-resistant alanine (S421A). We observed that S421D, rather than S421A, confers neuroprotection in hiPSC-derived neural cells. Although we observed no effect of S421D on mHTT clearance or axonal transport, two aspects previously reported to be impacted by phosphorylation of mHTT at S421, our analysis revealed modulation of several aspects of mitochondrial form and function. These include mitochondrial surface area, volume, and counts, as well as improved mitochondrial membrane potential and oxidative phosphorylation. Our study validates the protective role of pS421 on mHTT and highlights a facet of the relationship between mHTT and mitochondrial changes in the context of human physiology with potential relevance to the pathogenesis of HD.

A systematic review of morbidities suggestive of the multiple sclerosis prodrome.

INTRODUCTION: The identification of a prodromal phase in multiple sclerosis (MS) could have major implications for earlier recognition and management of MS. The authors conducted a systematic review assessing studies of morbidities before, or at, MS onset or diagnosis.Areas covered: Two independent reviewers searched Medline, Embase, Psycinfo and CINAHL from inception to February 8th, 2019. To be eligible, studies had to be published in English and report the relative occurrence of at least one morbidity or symptom before, or at, MS onset or diagnosis among MS cases in comparison to a control group not known to have MS. Findings were narratively synthesized. Study quality was assessed using the Newcastle-Ottawa scale (NOS, maximum score 9).Expert opinion: Twenty-nine studies were included, which comprised 83,590 MS cases and 396,343 controls. Most were case-control studies (25/29), 8/29 were of high quality (NOS≥8) and 19/29 examined the period before MS symptom onset. Most studies assessing anxiety, depression, migraine and lower cognitive performance found these conditions to be more prevalent before MS onset or diagnosis relative to controls. There was limited evidence to implicate other conditions. Thus, there is evidence that anxiety, depression, migraine and lower cognitive performance form part of the MS prodrome.