BDNF and TRiC-inspired reagent rescue cortical synaptic deficits in a mouse model of Huntington's disease.

Synaptic changes are early manifestations of neuronal dysfunction in Huntington's disease (HD). However, the mechanisms by which mutant HTT protein impacts synaptogenesis and function are not well understood. Herein we explored HD pathogenesis in the BACHD mouse model by examining synaptogenesis and function in long term primary cortical cultures. At DIV14 (days in vitro), BACHD cortical neurons showed no difference from WT neurons in synaptogenesis as revealed by colocalization of a pre-synaptic (Synapsin I) and a post-synaptic (PSD95) marker. From DIV21 to DIV35, BACHD neurons showed progressively reduced colocalization of Synapsin I and PSD95 relative to WT neurons. The deficits were effectively rescued by treatment of BACHD neurons with BDNF. The recombinant apical domain of CCT1 (ApiCCT1) yielded a partial rescuing effect. BACHD neurons also showed culture age-related significant functional deficits as revealed by multielectrode arrays (MEAs). These deficits were prevented by BDNF, whereas ApiCCT1 showed a less potent effect. These findings are evidence that deficits in BACHD synapse and function can be replicated in vitro and that BDNF or a TRiC-inspired reagent can potentially be protective against these changes in BACHD neurons. Our findings support the use of cellular models to further explicate HD pathogenesis and potential treatments.

Impacts of H2O2, SARM1 inhibition, and high NAm concentrations on Huntington's disease laser-induced degeneration.

Axonal degeneration is a key component of neurodegenerative diseases such as Huntington's disease (HD), Alzheimer's disease, and amyotrophic lateral sclerosis. Nicotinamide, an NAD+ precursor, has long since been implicated in axonal protection and reduction of degeneration. However, studies on nicotinamide (NAm) supplementation in humans indicate that NAm has no protective effect. Sterile alpha and toll/interleukin receptor motif-containing protein 1 (SARM1) regulates several cell responses to axonal damage and has been implicated in promoting neuronal degeneration. SARM1 inhibition seems to result in protection from neuronal degeneration while hydrogen peroxide has been implicated in oxidative stress and axonal degeneration. The effects of laser-induced axonal damage in wild-type and HD dorsal root ganglion cells treated with NAm, hydrogen peroxide (H2O2), and SARM1 inhibitor DSRM-3716 were investigated and the cell body width, axon width, axonal strength, and axon shrinkage post laser-induced injury were measured.

Full-field stimulus threshold testing: a scoping review of current practice.

The full-field stimulus threshold (FST) is a psychophysical measure of whole-field retinal light sensitivity. It can assess residual visual function in patients with severe retinal disease and is increasingly being adopted as an endpoint in clinical trials. FST applications in routine ophthalmology clinics are also growing, but as yet there is no formalised standard guidance for measuring FST. This scoping review explored current variability in FST conduct and reporting, with an aim to inform further evidence synthesis and consensus guidance. A comprehensive electronic search and review of the literature was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Extension for Scoping Reviews (PRISMA-ScR) checklist. Key source, participant, methodology and outcomes data from 85 included sources were qualitatively and quantitatively compared and summarised. Data from 85 sources highlight how the variability and insufficient reporting of FST methodology, including parameters such as units of flash luminance, colour, duration, test strategy and dark adaptation, can hinder comparison and interpretation of clinical significance across centres. The review also highlights an unmet need for paediatric-specific considerations for test optimisation. Further evidence synthesis, empirical research or structured panel consultation may be required to establish coherent standardised guidance on FST methodology and context or condition dependent modifications. Consistent reporting of core elements, most crucially the flash luminance equivalence to 0 dB reference level is a first step. The development of criteria for quality assurance, calibration and age-appropriate reference data generation may further strengthen rigour of measurement.

Developing and testing scales for home support service continuity (HSSC): cross-sectional studies in Canada and UK.

OBJECTIVES: Ensuring the continuity of home support services has become increasingly important due to challenges arising from ageing demographics and healthcare staffing shortages. However, there is a lack of validated measurements specifically designed for assessing service continuity in this context. The primary objective of this study is to develop and validate scales that capture the multidimensional nature of home support service continuity (HSSC), incorporating informational continuity, management continuity and relational continuity as its underlying components. Subsequently, these scales are employed to measure the overall level of continuity experienced within home support services and investigate its association with service quality. METHODS: This study used a cross-sectional survey design with convenience sampling. Direct caregivers in the UK were recruited through the Prolific UK online platform, while direct caregivers in British Columbia, Canada were recruited through local health authorities and home support agencies. A total of 550 direct caregivers completed the online survey following the approved ethics protocol. Structural equation modelling was employed to evaluate HSSC and it underlying components. Furthermore, the study investigated the influence of HSSC on service quality within these two samples. RESULTS: The quantitative tests confirmed that HSSC comprises three first-order continuity components. These components showed significant loadings on HSSC in the Canadian sample (N=367) (λinformational=0.81, λmanagement=0.93, λrelational=0.38) at p<0.01 level. This finding was further supported in the UK sample (N=183) (λinformational=0.87, λmanagement=0.90, λrelational=0.93) at p<0.01 level. In both samples, the overall HSSC showed a positive correlation with service quality (path coefficient for the Canadian sample: bHSSC_employee perceived service quality (EPSQ)=0.22, p<0.01; the UK sample: bHSSC_EPSQ=0.70, p<0.01). CONCLUSIONS: The results support the conceptualisation of HSSC as a second-order latent construct. The newly developed and validated scales for the three first-order constructs identify specific items that could be targeted to improve HSSC and service quality.

Integrating social and ecological considerations in floodplain relocation and restoration programs.

In the United States, most floodplain relocation (or buyout) programs focus on moving homeowners, then deal separately with what happens with the land afterward. These programs typically divide processes for relocation planning, engagement, funding, and implementation from those related to post-buyout land management and restoration. The structural and operational conditions that lead to this separation of roles and responsibilities miss out on opportunities to create more synergistic socio-ecological strategies that may produce healthier outcomes for both people and the environment. In other domains, research shows that healthy people and healthy environments can co-create each other through more virtuous cycles. In this perspective essay, we argue that we can better create such virtuous cycles in floodplain relocation programs by integrally considering social and ecological components. Such efforts can encourage more people to decide to relocate, thereby creating more contiguous places to restore. They can also empower more residents to help steward these sites, an action that in turn helps heal and strengthen flood-affected communities. These arguments, while particular to the United States, have resonance for floodplain management and land use planning worldwide.

High rate of false-positive postoperative venous thromboembolism identified using hospital ICD-10 coding.

The Health Roundtable, a national benchmarking body, identified our institution as an outlier with a high number of postoperative venous thromboembolism (VTE) events. We performed a retrospective study to determine the accuracy of hospital coding for the incidence and severity of postoperative VTE. Of 232 patients identified from ICD-10 coding, 52 (22.4%) were incorrectly coded. Approximately one third (n = 68) of all VTE were asymptomatic, diagnosed incidentally. Thus, coding data are inherently flawed with inaccuracy and overrepresent the true number of VTE events, with a substantial proportion of limited clinical relevance.

Equitable buyouts? Learning from state, county, and local floodplain management programs.

Climate change-exacerbated flooding has renewed interest in property buyouts as a pillar of managed retreat from coastal zones and floodplains in the United States. However, federal buyout programs are widely critiqued for being inaccessible and inequitable. To learn whether and how subnational buyout programs overcome these limitations, we examined five leading US state, county, and local buyout programs to see what they teach us about redesigning future federal policies. Our mixed-methods research used interviews and document analysis to develop case studies, juxtaposed subnational strategies against a review of critiques of federal buyouts, and focus group discussions with subnational buyout managers and experts to identify limitations of their programs. We find that subnational programs can be more inclusive and better respond to resident needs as compared to existing federal programs due to their access to dedicated, non-federal funding and their standing institutional status, which allows them to learn and evolve over time. Nevertheless, these programs lack coordination with and control over agencies that permit development and produce affordable housing. This gives buyout programs limited power in shaping the overall equity of who lives in floodplains and who has access to affordable, resilient housing after a buyout. Their experiences suggest federal programs can support managed retreat nationwide by increasing support for institutional and staff capacity at state and county levels, encouraging efforts to bridge institutional silos at subnational levels, and holistically mainstream climate considerations into regional floodplain development, affordable housing production, and flood risk mitigation.

A single cell death is disruptive to spontaneous Ca2+ activity in astrocytes.

Astrocytes in the brain are rapidly recruited to sites of injury where they phagocytose damaged material and take up neurotransmitters and ions to avoid the spreading of damaging molecules. In this study we investigate the calcium (Ca2+) response in astrocytes to nearby cell death. To induce cell death in a nearby cell we utilized a laser nanosurgery system to photolyze a selected cell from an established astrocyte cell line (Ast1). Our results show that the lysis of a nearby cell is disruptive to surrounding cells' Ca2+ activity. Additionally, astrocytes exhibit a Ca2+ transient in response to cell death which differs from the spontaneous oscillations occurring in astrocytes prior to cell lysis. We show that the primary source of the Ca2+ transient is the endoplasmic reticulum.

Mechanosensor Piezo1 mediates bimodal patterns of intracellular calcium and FAK signaling.

Piezo1 belongs to mechano-activatable cation channels serving as biological force sensors. However, the molecular events downstream of Piezo1 activation remain unclear. In this study, we used biosensors based on fluorescence resonance energy transfer (FRET) to investigate the dynamic modes of Piezo1-mediated signaling and revealed a bimodal pattern of Piezo1-induced intracellular calcium signaling. Laser-induced shockwaves (LIS) and its associated shear stress can mechanically activate Piezo1 to induce transient intracellular calcium (Ca[i] ) elevation, accompanied by an increase in FAK activity. Interestingly, multiple pulses of shockwave stimulation caused a more sustained calcium increase and a decrease in FAK activity. Similarly, tuning the degree of Piezo1 activation by titrating either the dosage of Piezo1 ligand Yoda1 or the expression level of Piezo1 produced a similar bimodal pattern of FAK responses. Further investigations revealed that SHP2 serves as an intermediate regulator mediating this bimodal pattern in Piezo1 sensing and signaling. These results suggest that the degrees of Piezo1 activation induced by both mechanical LIS and chemical ligand stimulation may determine downstream signaling characteristics.

Mitochondria dysfunction in Charcot Marie Tooth 2B Peripheral Sensory Neuropathy.

Rab7 GTPase regulates mitochondrial morphology and function. Missense mutation(s) of Rab7 underlies the pathogenesis of Charcot Marie Tooth 2B (CMT2B) peripheral neuropathy. Herein, we investigate how mitochondrial morphology and function are impacted by the CMT2B associated Rab7V162M mutation. In contrast to recent studies of using heterologous overexpression systems, our results demonstrate significant mitochondrial fragmentation in both human CMT2B patient fibroblasts and CMT2B embryonic fibroblasts (MEFs). Primary cultured E18 dorsal root ganglion (DRG) sensory neurons also show mitochondrial fragmentation and altered axonal mitochondrial movement. In addition, we demonstrate that inhibitors to either the mitochondrial fission protein Drp1 or to the nucleotide binding to Rab7 normalize the mitochondrial deficits in both MEFs and E18 cultured DRG neurons. Our study reveals, for the first time, that expression of CMT2B Rab7 mutation at the physiological level enhances Drp1 activity to promote mitochondrial fission, potentially underlying selective vulnerability of peripheral sensory neurons in CMT2B pathogenesis.

Transformative climate adaptation in the United States: Trends and prospects.

As climate change intensifies, civil society is increasingly calling for transformative adaptation that redresses drivers of climate vulnerability. We review trends in how U.S. federal government, private industry and civil society are planning for climate adaptation. We find growing divergence in their approaches and impacts. This incoherence increases maladaptive investment in climate-blind infrastructure, justice-blind reforms in financial and professional sectors, and greater societal vulnerability to climate impacts. If these actors were to proactively and deliberatively engage in transformative adaptation, they would need to address the material, relational and normative factors that hold current systems in place. Drawing on a review of transformation and collective impact literatures, we conclude with directions for research and policy engagement to support more transformative adaptation moving forward.

Laser-Induced Shockwave (LIS) to Study Neuronal Ca2+ Responses.

Laser-induced shockwaves (LIS) can be utilized as a method to subject cells to conditions similar to those occurring during a blast-induced traumatic brain injury. The pairing of LIS with genetically encoded biosensors allows researchers to monitor the immediate molecular events resulting from such an injury. In this study, we utilized the genetically encoded Ca2+ FRET biosensor D3CPV to study the immediate Ca2+ response to laser-induced shockwave in cortical neurons and Schwann cells. Our results show that both cell types exhibit a transient Ca2+ increase irrespective of extracellular Ca2+ conditions. LIS allows for the simultaneous monitoring of the effects of shear stress on cells, as well as nearby cell damage and death.

Inequalities through the lens of science.

Inequalities are ubiquitous in every society on Earth, and the COVID-2019 pandemic has exposed the marginalized communities that suffer the most. A warming planet will only magnify this gap. On the eve of the 26th session of the Conference of the Parties to the UNFCCC, this Voices asks: how can science inform and address inequalities?

Calcium Dynamics in Astrocytes During Cell Injury.

The changes in intracellular calcium concentration ([Ca2+]) following laser-induced cell injury in nearby cells were studied in primary mouse astrocytes selectively expressing the Ca2+ sensitive GFAP-Cre Salsa6f fluorescent tandem protein, in an Ast1 astrocyte cell line, and in primary mouse astrocytes loaded with Fluo4. Astrocytes in these three systems exhibit distinct changes in [Ca2+] following induced death of nearby cells. Changes in [Ca2+] appear to result from release of Ca2+ from intracellular organelles, as opposed to influx from the external medium. Salsa6f expressing astrocytes displayed dynamic Ca2+ changes throughout the phagocytic response, including lamellae protrusion, cytosolic signaling during vesicle formation, vesicle maturation, and vesicle tract formation. Our results demonstrate local changes in [Ca2+] are involved in the process of phagocytosis in astrocytes responding to cell corpses and/or debris.

Beyond flood risk reduction: How can green infrastructure advance both social justice and regional impact?

Green infrastructure is being pulled in divergent directions. As climate impacts intensify, advocates are promoting larger, ecosystem-scale strategies to help mitigate flood risks. Yet, research on existing urban greening projects finds that they can cause gentrification and displacement, suggesting that smaller projects may be more desirable from an equity perspective. This essay argues that cities need both large-scale and justice-enhancing nature-based solutions. They can help overcome tensions in these goals by (1) reframing green infrastructure as a way to support community development and integrated socio-ecological landscapes, and (2) advancing metropolitan regional governance strategies that alleviate municipal fiscal imperatives to maximize local land development. These proposals suggest that the practice of green infrastructure would benefit from diversifying its ranks to include social and government policy, community development, and agroecology, as well as learning from the Global South and those currently positioned as "off the map" of technical expertise. They also point to the need for interdisciplinary research that provides an evidence base for more transformative social, ecological, and governance strategies. While the essay focuses on the US context, it is relevant to an international audience given that similar challenges confront cities worldwide and that it highlights how the Global North can learn from the Global South.

LSD1 mediated changes in the local redox environment during the DNA damage response.

The redox state of the cell can be affected by many cellular conditions. In this study we show that detectable reactive oxygen species (ROS) are also generated in response to DNA damage by the chromatin remodeling factor and monoamine oxidase LSD1/KDM1A. This raised the possibility that the localized generation of hydrogen peroxide produced by LSD1 may affect the function of proximally located DNA repair proteins. The two major pathways for repair of DNA double-strand breaks (DSBs) are homologous recombination (HR) and non-homologous end joining (NHEJ). Cells were exposed to low levels of ectopic H2O2, DNA breaks generated by laser light, and recruitment kinetics of NHEJ protein Ku80 to DNA damage sites determined. Ku80 recruitment to damage sites was significantly decreased in cells pretreated with H2O2 while HR end binding protein Nbs1 was increased. This suggests that the DNA repair pathway choice has the potential to be modulated by the local redox state. This has implications for chemotherapeutic approaches involving generating DNA damage to target actively dividing cancer cells, which may be more or less effective dependent on the redox state of the targeted cells and the predominant repair pathway required to repair the type of DNA damage generated.

A positive-feedback-based mechanism for constriction rate acceleration during cytokinesis in Caenorhabditis elegans.

To ensure timely cytokinesis, the equatorial actomyosin contractile ring constricts at a relatively constant rate despite its progressively decreasing size. Thus, the per-unit-length constriction rate increases as ring perimeter decreases. To understand this acceleration, we monitored cortical surface and ring component dynamics during the first cytokinesis of the Caenorhabditis elegans embryo. We found that, per unit length, the amount of ring components (myosin, anillin) and the constriction rate increase with parallel exponential kinetics. Quantitative analysis of cortical flow indicated that the cortex within the ring is compressed along the axis perpendicular to the ring, and the per-unit-length rate of cortical compression increases during constriction in proportion to ring myosin. We propose that positive feedback between ring myosin and compression-driven flow of cortex into the ring drives an exponential increase in the per-unit-length amount of ring myosin to maintain a high ring constriction rate and support this proposal with an analytical mathematical model.

Visualizing Spatiotemporal Dynamics of Intercellular Mechanotransmission upon Wounding.

During cell-to-cell communications, the interplay between physical and biochemical cues is essential for informational exchange and functional coordination, especially in multicellular organisms. However, it remains a challenge to visualize intercellular signaling dynamics in single live cells. Here, we report a photonic approach, based on laser microscissors and Förster resonance energy transfer (FRET) microscopy, to study intercellular signaling transmission. First, using our high-throughput screening platform, we developed a highly sensitive FRET-based biosensor (SCAGE) for Src kinase, a key regulator of intercellular interactions and signaling cascades. Notably, SCAGE showed a more than 40-fold sensitivity enhancement than the original biosensor in live mammalian cells. Next, upon local severance of physical intercellular connections by femtosecond laser pulses, SCAGE enabled the visualization of a transient Src activation across neighboring cells. Lastly, we found that this observed transient Src activation following the loss of cell-cell contacts depends on the passive structural support of cytoskeleton but not on the active actomyosin contractility. Hence, by precisely introducing local physical perturbations and directly visualizing spatiotemporal transmission of ensuing signaling events, our integrated approach could be broadly applied to mimic and investigate the wounding process at single-cell resolutions. This integrated approach with highly sensitive FRET-based biosensors provides a unique system to advance our in-depth understanding of molecular mechanisms underlying the physical-biochemical basis of intercellular coupling and wounding processes.

A Mouse Model for Dietary Xenosialitis: ANTIBODIES TO XENOGLYCAN CAN REDUCE FERTILITY.

Humans can incorporate the xenoglycan N-glycolylneuraminic acid (Neu5Gc) from the diet into reproductive tissues and secretions. Most humans also have circulating antibodies specific for this dietary xenoglycan. The potential for inflammation induced by incorporated Neu5Gc and circulating anti-Neu5Gc antibodies, termed xenosialitis, has been discussed as a factor influencing several human diseases. Potential effects of xenosialitis on human fertility remain unknown. Here, we investigate possible adverse effects of the presence of Neu5Gc on sperm or endometrium combined with anti-Neu5Gc antibodies in semen or uterine secretions in a mouse model. We use Cmah(-/-) mice, humanized for Neu5Gc deficiency. We find that the viability, migration, and capacitation of sperm with incorporated Neu5Gc are negatively affected when these are exposed to anti-Neu5Gc antibodies. In addition, we find that after copulation, activated uterine neutrophils and macrophages show increased phagocytosis of sperm in the presence of anti-Neu5Gc antibodies via the complement receptor 3 (C3R) and Fcγ I/II/III (Fc receptor). Furthermore, Neu5Gc in endometrial cells combined with the presence of anti-Neu5Gc antibodies alters the receptivity and decidualization of endometrial explants. These studies provide mechanistic insights on how Neu5Gc on sperm and/or endometrium combined with anti-Neu5Gc antibodies in semen and uterine fluid might contribute to unexplained human infertility.

Rat embryonic hippocampus and induced pluripotent stem cell derived cultured neurons recover from laser-induced subaxotomy.

Axonal injury and stress have long been thought to play a pathogenic role in a variety of neurodegenerative diseases. However, a model for studying single-cell axonal injury in mammalian cells and the processes of repair has not been established. The purpose of this study was to examine the response of neuronal growth cones to laser-induced axonal damage in cultures of embryonic rat hippocampal neurons and induced pluripotent stem cell (iPSC) derived human neurons. A 532-nm pulsed [Formula: see text] picosecond laser was focused to a diffraction limited spot at a precise location on an axon using a laser energy/power that did not rupture the cell membrane (subaxotomy). Subsequent time series images were taken to follow axonal recovery and growth cone dynamics. After laser subaxotomy, axons thinned at the damage site and initiated a dynamic cytoskeletal remodeling process to restore axonal thickness. The growth cone was observed to play a role in the repair process in both hippocampal and iPSC-derived neurons. Immunofluorescence staining confirmed structural tubulin damage and revealed initial phases of actin-based cytoskeletal remodeling at the damage site. The results of this study indicate that there is a repeatable and cross-species repair response of axons and growth cones after laser-induced damage.