Ethylene-forming enzyme (EFE) is an iron(II)-dependent dioxygenase that fragments 2-oxoglutarate (2OG) to ethylene (from C3 and C4) and 3 equivs of carbon dioxide (from C1, C2, and C5). This major ...ethylene-forming pathway requires l-arginine as the effector and competes with a minor pathway that merely decarboxylates 2OG to succinate as it oxidatively fragments l-arginine. We previously proposed that ethylene forms in a polar-concerted (Grob-like) fragmentation of a (2-carboxyethyl)carbonatoiron(II) intermediate, formed by the coupling of a C3–C5-derived propion-3-yl radical to a C1-derived carbonate coordinated to the Fe(III) cofactor. Replacement of one or both C4 hydrogens of 2OG by fluorine, methyl, or hydroxyl favored the elimination products 2-(F1–2/Me/OH)-3-hydroxypropionate and CO2 over the expected olefin or carbonyl products, implying strict stereoelectronic requirements in the final step, as is known for Grob fragmentations. Here, we substituted active-site residues expected to interact sterically with the proposed Grob intermediate, aiming to disrupt or enable the antiperiplanar disposition of the carboxylate electrofuge and carbonate nucleofuge required for concerted fragmentation. The bulk-increasing A198L substitution barely affects the first partition between the major and minor pathways but then, as intended, markedly diminishes ethylene production in favor of 3-hydroxypropionate. Conversely, the bulk-diminishing L206V substitution enables propylene formation from (4R)-methyl-2OG, presumably by allowing the otherwise sterically disfavored antiperiplanar conformation of the Grob intermediate bearing the extra methyl group. The results provide additional evidence for a polar-concerted ethylene-yielding step and thus for the proposed radical-polar crossover via substrate-radical coupling to the Fe(III)-coordinated carbonate.
Microbial ethylene-forming enzyme (EFE) converts the C3–C4 fragment of the ubiquitous primary metabolite 2-oxoglutarate (2OG) to its namesake alkene product. This reaction is very different from the ...simple decarboxylation of 2OG to succinate promoted by related enzymes and has inspired disparate mechanistic hypotheses. We show that EFE produces stereochemically random (equal cis and trans) 1,2-
H
-ethylene from (3
,4
)-
H
-2OG, appends an oxygen from O
on the C1-derived (bi)carbonate, and can be diverted to ω-hydroxylated monoacid products by modifications to 2OG or the enzyme. These results implicate an unusual radical-polar hybrid mechanism involving iron(II)-coordinated acylperoxycarbonate and alkylcarbonate intermediates. The mechanism explains how EFE accesses a high-energy carboxyl radical to initiate its fragmentation cascade, and it hints at capabilities of 2OG-dependent enzymes that may await discovery and exploitation.
Ethylene-forming enzyme (EFE) is an ambifunctional iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase. In its major (EF) reaction, it converts carbons 1, 2, and 5 of 2OG to CO2 and carbons 3 ...and 4 to ethylene, a four-electron oxidation drastically different from the simpler decarboxylation of 2OG to succinate mediated by all other Fe/2OG enzymes. EFE also catalyzes a minor reaction, in which the normal decarboxylation is coupled to oxidation of l-arginine (a required activator for the EF pathway), resulting in its conversion to l-glutamate semialdehyde and guanidine. Here we show that, consistent with precedent, the l-Arg-oxidation (RO) pathway proceeds via an iron(IV)–oxo (ferryl) intermediate. Use of 5,5-2H2-l-Arg slows decay of the ferryl complex by >16-fold, implying that RO is initiated by hydrogen-atom transfer (HAT) from C5. That this large substrate deuterium kinetic isotope effect has no impact on the EF:RO partition ratio implies that the same ferryl intermediate cannot be on the EF pathway; the pathways must diverge earlier. Consistent with this conclusion, the variant enzyme bearing the Asp191Glu ligand substitution accumulates ∼4 times as much of the ferryl complex as the wild-type enzyme and exhibits a ∼40-fold diminished EF:RO partition ratio. The selective detriment of this nearly conservative substitution to the EF pathway implies that it has unusually stringent stereoelectronic requirements. An active-site, like-charge guanidinium pair, which involves the l-Arg substrate/activator and is unique to EFE among four crystallographically characterized l-Arg-modifying Fe/2OG oxygenases, may serve to selectively stabilize the transition state leading to the unique EF branch.
Abstract
Background
To positively impact the social determinants of health, disabled people need to contribute to policy planning and programme development. However, they report barriers to engaging ...meaningfully in consultation processes. Additionally, their recommendations may not be articulated in ways that policy planners can readily use. This gap contributes to health outcome inequities. Participatory co-production methods have the potential to improve policy responsiveness. This research will use innovative methods to generate tools for co-producing knowledge in health-related policy areas, empowering disabled people to articulate experience, expertise and insights promoting equitable health policy and programme development within Aotearoa New Zealand. To develop these methods, as an exemplar, we will partner with both tāngata whaikaha Māori and disabled people to co-produce policy recommendations around housing and home (kāinga)—developing a nuanced understanding of the contexts in which disabled people can access and maintain kāinga meeting their needs and aspirations.
Methods
Participatory co-production methods with disabled people, embedded within a realist methodological approach, will develop theories on how best to co-produce and effectively articulate knowledge to address equitable health-related policy and programme development—considering what works for whom under what conditions. Theory-building workshops
(Phase 1)
and qualitative surveys
(Phase 2)
will explore contexts and resources (i.e., at individual, social and environmental levels) supporting them to access and maintain kāinga that best meets their needs and aspirations. In
Phase 3,
a realist review with embedded co-production workshops will synthesise evidence and co-produce knowledge from published literature and non-published reports. Finally, in
Phase 4
, co-produced knowledge from all phases will be synthesised to develop two key research outputs: housing policy recommendations and innovative co-production methods and tools empowering disabled people to create, synthesise and articulate knowledge to planners of health-related policy.
Discussion
This research will develop participatory co-production methods and tools to support future creation, synthesis and articulation of the knowledge and experiences of disabled people, contributing to policies that positively impact their social determinants of health.
Societal culture, space, and structure have been unprecedentedly disrupted during the COVID-19 pandemic creating disproportionate vulnerability for disabled people. However, the upheaval of many ...societal conditions has presented enabling opportunities for disabled people. We report on interviews with 30 disabled people during the first four-week Aotearoa New Zealand COVID-19 lockdown. Three key themes were interpreted: “I am experiencing less disability on a daily basis,” encapsulating the experience of reduced disabling barriers for participants; “Working from home: the flexibility I have been asking for,” summarizing the benefits of functioning in an enabling home/work space; and “Social connection opportunities are the same for everyone,” overviewing participants reports that online opportunities presented a greater sense of belonging than before lockdown. Study findings highlight that despite a constant fear of the negative impact posed by COVID-19, there were numerous opportunities to reduce ablism through applying empowering factors inherent in novel cultural spaces.
Rates of return-to-work after stroke are low, yet work is known to positively impact people's wellbeing and overall health outcomes.
To understand return-to-work trajectories, barriers encountered, ...and resources that may be used to better support participants during early recovery and rehabilitation.
The experiences of 31 participants (aged 25-76 years) who had or had not returned to work after stroke were explored.
Interview data were analysed using reflexive thematic analysis methods within a broader realist research approach.
Participants identified an early need to explore a changed and changing occupational identity within a range of affirming environments, thereby ascertaining their return-to-work options early after stroke. The results articulate resources participants identified as most important for their occupational explorations. Theme 1 provides an overview of opportunities participants found helpful when exploring work options, while theme 2 explores fundamental principles for ensuring the provided opportunities were perceived as beneficial. Finally, theme 3 provides an overview of prioritized return-to-work service characteristics.
The range and severity of impairments experienced by people following stroke are broad, and therefore their return-to-work needs are diverse. However, all participants, irrespective of impairment, highlighted the need for early opportunities to explore their changed and changing occupational identity.
IntroductionReturn to work after spinal cord injury (SCI) is linked to well-being and better physical and mental health outcomes. In New Zealand, work rates after SCI are lower than the general ...population. Vocational rehabilitation is one method of supporting return to work. Although the best model has not been determined, there is evidence supporting early intervention. However, most vocational rehabilitation research focuses on return to work outcomes without considering why vocational rehabilitation works, for whom and under what circumstances. Given this knowledge gap, we detail a realist synthesis protocol aiming to explain how contextual factors trigger relevant mechanisms to facilitate return to work after SCI.Methods and analysisThis study will use a realist synthesis approach, following Realist And MEta-narrative Evidence Synthesis: Evolving Standards (RAMESES) guidelines. First, we will undertake a realist review of existing published and grey literature. Second, to assist with theoretical conceptualisation, we will interview people with SCI who have received vocational rehabilitation. Finally, we will survey people with SCI who received early vocational rehabilitation for theoretical testing and refinement.Ethics and disseminationUniversity of Otago Ethics Committee (Reference H19/170) has been obtained. A knowledge translation event will address issues relevant to wider implementation of the intervention and study findings. Findings will be also be disseminated through peer reviewed journals, conference presentations and formal reports.
This manuscript considers the drivers towards inclusive research in the field of disability and rehabilitation; including some of the tools and frameworks that may support its realisation. We, a ...group of researchers engaged in rehabilitation research from lived experience and ‘conventional’ (non-lived experience) positions, reflect on our collective endeavours to bring about inclusion in research and specify the systemic factors constraining inclusion in research. We conclude by asking the following: how might we reimagine systems where the mechanisms of research production are in the hands of those impacted by the research, and where are intersectionalities both sought and valued?
Control groups are used in clinical trials to increase confidence that any improvements in patient outcomes are due the therapy under investigation and not to other factors. The reported effect size ...of any intervention is estimated from differences in outcomes achieved by intervention participants in comparison to control participants. Clinical heterogeneity in control groups across different studies can make the pooling of data from these studies in one meta-analysis questionable or reduce certainty in their results.
The aim of this study was to evaluate: 1) the variability in the types of control groups used in studies that have been pooled in meta-analyses in Cochrane reviews on neurorehabilitation interventions; and 2) how authors of Cochrane reviews on neurorehabilitation interventions have taken information about control groups into consideration when making decisions to undertake meta-analyses and interpreting their results.
We searched the Cochrane library for reviews on neurorehabilitation interventions published between 2012 and 2016 that included at least one meta-analysis involving a control group. We extracted data from included reviews on the review characteristics, the characteristics of the included meta-analyses, and any information on how the review authors managed control groups in the conduct and interpretation of meta-analyses.
The 43 included reviews pooled data from 358 clinical trials, with an average of 5±5 clinical trials (range: 2-45) contributing to each meta-analysis. The majority of clinical trials involved a control group containing active treatments (61.7%; 221 of 358), often "treatment as usual" controls without any additional placebo or sham intervention. Over half (58.1%; 25 of 43) of the included meta-analyses involved pooling of data from studies with a mix of different types of control groups, with an additional 25.6% pooling data from studies where control participants had received a range of different active treatments. The influence of different control groups on the summary results from meta-analyses was not analyzed in 21 (48.8%) of the included reviews.
Further work is needed to develop: standardized ways to categorize control conditions in rehabilitation trials; more guidance on reporting criteria for control groups in rehabilitation trials; and agreed methods for managing different control types in one meta-analysis.
Purpose: Therapeutic horse riding aims to improve the health of children and young people experiencing disability; however, its benefits across a range of health domains, particularly the impact on ...participation outcomes, are not well known. This research evaluated to what extent there was a change in riders balance, functional performance, social responsiveness, quality of life and participation outcomes as a result of therapeutic horse riding.
Methods: A multiple-baseline across participants (n = 12) single-case experimental design, with randomly allocated baseline phase lengths, quantitatively evaluated how riders responded to a 20-week intervention.
Results: Social participation outcomes measured using the Canadian Occupational Performance Measure demonstrated the most consistent positive between-phase differences (performance ES = 1.20, 95% CI 0.82, 1.63; satisfaction ES = 1.11, 95% CI 0.73, 1.55). A causal relationship was seen in three riders, but improvements only reached clinical significance for two riders when accounting for phase data trends. No significant outcome patterns were found comparing riders with principally physical impairments to those with principally psychosocial impairments.
Conclusions: Being involved in therapeutic horse riding may improve rider's social participation in home, school and community settings. We postulate that rider self-concept development may be a mechanism of treatment effect leading to participation-level changes.
Implications for rehabilitation
Social participation was the health outcome demonstrating the most consistent change following therapeutic horse riding, regardless of rider impairment.
Therapeutic horse riding can improve social participation in settings beyond the riding arena.
Greater intervention tailoring based on rider responses may enhance therapeutic horse riding intervention effects.
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