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  1. Article ; Online: Diastereoselective Ammonium-Directed Epoxidation in the Asymmetric Syntheses of Dihydroconduramines (+)-C-2, (-)-C-2, (+)-D-2, (+)-E-2, (+)-F-2, and (-)-F-2.

    Da Silva Pinto, Solange / Davies, Stephen G / Fletcher, Ai M / Roberts, Paul M / Thomson, James E

    The Journal of organic chemistry

    2018  Volume 83, Issue 17, Page(s) 9939–9957

    Abstract: Epoxidations (40% aq ... ...

    Abstract Epoxidations (40% aq HBF
    Language English
    Publishing date 2018-08-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/acs.joc.8b01359
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Diastereoselective Ammonium-Directed Epoxidation in the Asymmetric Syntheses of Dihydroconduramines (+)-C-2, (−)-C-2, (+)-D-2, (+)-E-2, (+)-F-2, and (−)-F-2

    Da Silva Pinto, Solange / Ai M. Fletcher / James E. Thomson / Paul M. Roberts / Stephen G. Davies

    Journal of organic chemistry. 2018 July 24, v. 83, no. 17

    2018  

    Abstract: ... dihydroconduramines (+)-C-2, (−)-C-2, (+)-D-2, (+)-E-2, (+)-F-2, and (−)-F-2 (>99% ee in each case). ...

    Abstract Epoxidations (40% aq HBF4 then m-CPBA) of racemic cis-2-(N-benzylamino)cyclohex-3-en-1-ol and racemic cis-2-(N,N-dibenzylamino)cyclohex-3-en-1-ol proceed with very high levels of diastereoselectivity (>95:5 dr). The latter is in direct contrast to the epoxidation of the corresponding trans-diastereoisomer (which proceeds with essentially no selectivity), showing that the relative configuration of the substrate dramatically influences the diastereoselectivity in these instances. Meanwhile, epoxidations of enantiopure (1R,2S,αR)-2-[(N-α-methylbenzyl)amino]cyclohex-3-en-1-ol and (1S,2R,αR)-2-[(N-α-methylbenzyl)amino]cyclohex-3-en-1-ol [surrogates for the enantiomers of cis-2-(N-benzylamino)cyclohex-3-en-1-ol] proceed with complete diastereoselectivity (>95:5 dr) under the same conditions, showing that neither the presence of the α-methyl group nor the relative configuration of the α-methylbenzyl stereocenter have an effect upon the established level of diastereoslectivity in these cases. In contrast, epoxidations of enantiopure (1R,2S,αR)-2-[N-benzyl-N-(α-methylbenzyl)amino]cyclohex-3-en-1-ol and (1S,2R,αR)-2-[N-benzyl-N-(α-methylbenzyl)amino]cyclohex-3-en-1-ol [surrogates for the enantiomers of cis-2-(N,N-dibenzylamino)cyclohex-3-en-1-ol] proceed with lower diastereoselectivity (∼70:30 dr). Thus, the presence of the α-methyl group has a detrimental effect on the established level of diastereoselectivity in these cases (although again the relative configuration of the α-methylbenzyl stereocenter is unimportant). The diastereoselective epoxidation pathway is used to enable the asymmetric syntheses of six hitherto unknown, enantiopure dihydroconduramines (+)-C-2, (−)-C-2, (+)-D-2, (+)-E-2, (+)-F-2, and (−)-F-2 (>99% ee in each case).
    Keywords diastereoselectivity ; enantiomers ; epoxidation reactions ; moieties ; organic chemistry ; organic compounds
    Language English
    Dates of publication 2018-0724
    Size p. 9939-9957.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/acs.joc.8b01359
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Asymmetric syntheses of APTO and AETD: the β-amino acid fragments within microsclerodermins C, D, and E.

    Davies, Stephen G / Fletcher, Ai M / Foster, Emma M / Lee, James A / Roberts, Paul M / Thomson, James E

    The Journal of organic chemistry

    2013  Volume 78, Issue 6, Page(s) 2500–2510

    Abstract: ... within microsclerodermins C, D, and E, are reported. The conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide ...

    Abstract Efficient asymmetric syntheses of APTO and AETD, the highly functionalized β-amino acid fragments within microsclerodermins C, D, and E, are reported. The conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl (E,E)-7-(triisopropylsilyloxy)hepta-2,4-dienoate and in situ enolate oxidation with (-)-camphorsulfonyloxaziridine, diastereoselective dihydroxylation of a 2,3-syn-γ,δ-unsaturated-α-hydroxy-β-amino ester derivative under Donohoe conditions, and a Julia-Kocieński olefination were used as the key steps.
    MeSH term(s) Amino Acids, Neutral/chemical synthesis ; Amino Acids, Neutral/chemistry ; Lithium/chemistry ; Molecular Structure ; Oxidation-Reduction ; Peptide Fragments/chemical synthesis ; Peptide Fragments/chemistry ; Peptides, Cyclic/chemical synthesis ; Peptides, Cyclic/chemistry ; Stereoisomerism
    Chemical Substances Amino Acids, Neutral ; Peptide Fragments ; Peptides, Cyclic ; microsclerodermin C ; microsclerodermin D ; microsclerodermin E ; Lithium (9FN79X2M3F)
    Language English
    Publishing date 2013-03-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/jo302731m
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Asymmetric Syntheses of APTO and AETD: the β-Amino Acid Fragments within Microsclerodermins C, D, and E

    Davies, Stephen G / Fletcher Ai M / Foster Emma M / Lee James A / Roberts Paul M / Thomson James E

    Journal of organic chemistry. 2013 Mar. 15, v. 78, no. 6

    2013  

    Abstract: ... within microsclerodermins C, D, and E, are reported. The conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide ...

    Abstract Efficient asymmetric syntheses of APTO and AETD, the highly functionalized β-amino acid fragments within microsclerodermins C, D, and E, are reported. The conjugate addition of lithium (R)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl (E,E)-7-(triisopropylsilyloxy)hepta-2,4-dienoate and in situ enolate oxidation with (−)-camphorsulfonyloxaziridine, diastereoselective dihydroxylation of a 2,3-syn-γ,δ-unsaturated-α-hydroxy-β-amino ester derivative under Donohoe conditions, and a Julia–Kocieński olefination were used as the key steps.
    Keywords amino acids ; chemical structure ; diastereoselectivity ; dihydroxylation ; lithium ; organic chemistry ; organic compounds ; oxidation
    Language English
    Dates of publication 2013-0315
    Size p. 2500-2510.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021%2Fjo302731m
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Multilayered.

    Fletcher, Adrian A

    Psychiatric services (Washington, D.C.)

    2022  Volume 73, Issue 9, Page(s) 1059–1060

    MeSH term(s) Child ; Child Abuse ; Child Abuse, Sexual ; Humans ; Psychiatric Status Rating Scales
    Language English
    Publishing date 2022-03-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1220173-x
    ISSN 1557-9700 ; 1075-2730
    ISSN (online) 1557-9700
    ISSN 1075-2730
    DOI 10.1176/appi.ps.202100706
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: A Compact Two-Loudspeaker Virtual Sound Reproduction System for Clinical Testing of Spatial Hearing With Hearing-Assistive Devices.

    Hamdan, Eric C / Fletcher, Mark D

    Frontiers in neuroscience

    2022  Volume 15, Page(s) 725127

    Abstract: Exciting developments in hearing aid and cochlear implant technology for linking signal processing across the ears have improved spatial hearing outcomes. This has resulted in an increased emphasis on clinical assessment of the spatial hearing abilities ... ...

    Abstract Exciting developments in hearing aid and cochlear implant technology for linking signal processing across the ears have improved spatial hearing outcomes. This has resulted in an increased emphasis on clinical assessment of the spatial hearing abilities of hearing-assistive device users. Effective assessment of spatial hearing currently requires a large and costly loudspeaker array system, housed in a heavily acoustically treated testing room. This imposes economic and logistical constraints that limit proliferation of array systems, particularly in developing nations. Despite their size and cost, the ability of current clinical array systems to reproduce realistic spatial sound fields is limited, which substantially reduces the range of realistic acoustic scenes that can be used for diagnostic testing. We propose an alternative low-cost, compact virtual acoustics system with just two loudspeakers. This system uses crosstalk cancelation to reproduce pressure signals at the device microphones that match those for real-world sound sources. Furthermore, in contrast to clinical array systems, the system can adapt to different room acoustics, removing the requirement for a heavily acoustically treated testing environment. We conducted a proof-of-concept study in two stages: in the first, we evaluated the physical performance of the system for a stationary listener in anechoic conditions and in a small audiological testing booth with moderate acoustic treatment. To do this, a head and torso simulator was fitted with specially adapted hearing-assistive devices that allowed direct access to the microphone signals. These microphone signals were compared for real and virtual sound sources at numerous source locations. In the second stage, we quantified the system's robustness to head rotations with and without the system adapting for head position. In the stationary case, the system was found to be highly effective at reproducing signals, such as speech, at all tested source locations. When head rotation was added, it performed well for rotations of up to 2°, even without adapting. However, performance improved markedly for larger rotations when the system adapted. These findings suggest that a compact, low-cost virtual acoustics system can give wider access to advanced and ecologically valid audiological testing, which could substantially improve clinical assessment of hearing-assistive device users.
    Language English
    Publishing date 2022-01-28
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2411902-7
    ISSN 1662-453X ; 1662-4548
    ISSN (online) 1662-453X
    ISSN 1662-4548
    DOI 10.3389/fnins.2021.725127
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  7. Article ; Online: A Novel Classification of Intraoperative Ulnar Nerve Instability to Aid Transposition Surgery.

    Pohl, Nicholas / Brush, Parker / Aita, Daren / Kistler, Justin / Jones, Christopher / Tosti, Rick / Fletcher, Daniel

    Journal of shoulder and elbow surgery

    2024  

    Abstract: ... viewings, 21 days apart. Variables collected were ulnar subluxation classification (A, B, C or D) and ... classification selections were regrouped into classes A/B or C/D, 100% of reviewers had substantial interobserver ... a confidence metric. Subsequent to primary data collection, classification grading was stratified into A/B or C ...

    Abstract Hypothesis: The purpose of this study was to compare inter-and intraobserver agreement of a novel intraoperative subluxation classification for patients undergoing ulnar nerve surgery at the elbow. We hypothesize there will be strong inter- and intraobserver agreement of the four-category classification system and reviewers will have substantial confidence while reviewing the classification system.
    Methods: Four blinded fellowship-trained orthopedic hand surgeons reviewed 25 videos in total on two separate viewings, 21 days apart. Variables collected were ulnar subluxation classification (A, B, C or D) and a confidence metric. Subsequent to primary data collection, classification grading was stratified into A/B or C/D subgroups for further analysis. Cohen's kappa scores were used to evaluate all variables collected in this study. The interpretation of kappa scores included ≤0.0 as no agreement, 0.01-0.20 as none to slight, 0.21-0.40 as fair, 0.41-0.60 as moderate, 0.61-0.80 as substantial, and 0.81-1.0 as almost perfect agreement.
    Results: Interobserver agreement of subluxation classification as a four-category scale demonstrated a moderate agreement on first viewing, second viewing, and when both viewings were combined (kappa=0.51, 0.51, and 0.51 respectively). Seventy-five percent (3 out of 4) of reviewers had moderate intraobserver agreement for ulnar nerve subluxation classification while one reviewer had substantial intraobserver classification (kappa= 0.72). Overall, there was high confidence in 65% of classification scores in the second round of viewing, which improved from 58% in the first viewing round. When ulnar subluxation classification selections were regrouped into classes A/B or C/D, 100% of reviewers had substantial interobserver (kappa=0.74 - 0.75) and substantial to almost perfect intraobserver (kappa=0.71 to 0.91) agreement.
    Conclusions: The four-category classification was reproducible within and between reviewers. Agreement appeared to increase when simplifying the classification to two categories, which may provide guidance to surgical decision making. The validation of a reproducible classification scheme for intraoperative ulnar subluxation may aid with decision making and further postoperative outcomes research.
    Language English
    Publishing date 2024-04-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1170782-3
    ISSN 1532-6500 ; 1058-2746
    ISSN (online) 1532-6500
    ISSN 1058-2746
    DOI 10.1016/j.jse.2024.02.030
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Psychotic illness in people with Prader-Willi syndrome: a systematic review of clinical presentation, course and phenomenology.

    Aman, Lucie C S / Lester, Suzannah D / Holland, Anthony J / Fletcher, Paul C

    Orphanet journal of rare diseases

    2024  Volume 19, Issue 1, Page(s) 69

    Abstract: Background: Prader-Willi syndrome (PWS) is a rare and complex neurodevelopmental disorder resulting from absent paternal expression of maternally imprinted genes at chromosomal locus 15q11-13. This absence of expression occurs as a consequence of a ... ...

    Abstract Background: Prader-Willi syndrome (PWS) is a rare and complex neurodevelopmental disorder resulting from absent paternal expression of maternally imprinted genes at chromosomal locus 15q11-13. This absence of expression occurs as a consequence of a deletion on the chromosome 15 of paternal origin (ca. 70%), a chromosome 15 maternal uniparental disomy (mUPD; ca. 25%), or an imprinting centre defect (IC; ca. 1-3%). At birth, individuals with PWS are severely hypotonic and fail to thrive. Hyperphagia and characteristic physical and neuropsychiatric phenotypes become apparent during childhood. The risk for the development of a co-morbid psychotic illness increases during the teenage years, specifically in those with PWS due to the presence of an mUPD. The primary aim of this literature review is to inform clinical practice. To achieve this, we have undertaken a systematic analysis of the clinical research literature on prevalence, presentation, course, characteristics, diagnosis and treatment of psychotic illness in people with PWS. The secondary aim is to identify clinical aspects of psychotic illness in PWS in need of further investigation.
    Methods and findings: A systematic literature review on psychosis in PWS was conducted on the databases Web of Knowledge, PubMed and Scopus, using the terms "((Prader-Willi syndrome) OR (Prader Willi Syndrome)) AND ((psychosis) OR (psychotic illness))". All articles written in English and reporting original human research were reviewed. In all but three of the 16 cohort studies in which the genetic types were known, the authors reported higher rates of psychosis in people with PWS resulting from an mUPD, compared to those with the deletion subtype of PWS. When psychosis was present the presentation was psychosis similar regardless of genetic type and was usually characterised by an acute onset of hallucinations and delusions accompanied by confusion, anxiety and motor symptoms.
    Conclusions: The onset of confusion, an affective cyclical pattern with the presence of abnormal mental beliefs and experiences, usually of rapid onset is suggestive of the development of psychotic illness. Phenomenologically, this psychosis in people with PWS is atypical in comparison to schizophrenia and bipolar disorder in the general population. The relationship to psychosis in the general population and the optimum treatments remain uncertain.
    MeSH term(s) Adolescent ; Infant, Newborn ; Humans ; Prader-Willi Syndrome/diagnosis ; Psychotic Disorders/genetics ; Comorbidity ; Family ; Anxiety ; Chromosomes, Human, Pair 15/genetics
    Language English
    Publishing date 2024-02-15
    Publishing country England
    Document type Systematic Review ; Journal Article ; Review
    ZDB-ID 2225857-7
    ISSN 1750-1172 ; 1750-1172
    ISSN (online) 1750-1172
    ISSN 1750-1172
    DOI 10.1186/s13023-024-03026-y
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  9. Article ; Online: Water use strategy determines the effectiveness of internal water storage for trees growing in biofilters subject to repeated droughts.

    Hanley, Paul A / Livesley, Stephen J / Fletcher, Tim D / Szota, Christopher

    The Science of the total environment

    2023  Volume 894, Page(s) 164762

    Abstract: ... for A. flexuosa, whereas C. viminalis reduced leaf loss but saw no change in water use or drought stress ... after repeated droughts, while C. viminalis experienced reduced recovery ability. It is recommended ... stomatal control, such as C. viminalis, the internal water storage volume needs to be increased to avoid ...

    Abstract Impervious surfaces create large volumes of stormwater which degrades receiving waterways. Incorporating trees into biofilters can increase evapotranspiration and therefore reduce stormwater runoff. Tree species with i) high water use, ii) drought tolerance and iii) rapid and full recovery after drought have been suggested for biofilters to maximise runoff reduction while minimising drought stress. Moisture availability fluctuates greatly in biofilter substrates and trees growing in biofilters will likely experience multiple, extended drought events that increase trade-offs between these traits. Providing an internal water storage has the potential to reduce tree drought stress and increase evapotranspiration. Two urban tree species (Agonis flexuosa and Callistemon viminalis) were grown in plastic drums with biofilter profiles. Three irrigation treatments were used: well-watered, drought with an internal water storage and drought without an internal water storage. Transpiration, leaf water potential and biomass were measured to determine the effect of biofilter internal water storage and repeated drought events on tree water use, drought stress and growth. Biofilter internal water storage improved water use and reduced drought stress for A. flexuosa, whereas C. viminalis reduced leaf loss but saw no change in water use or drought stress. A. flexuosa with biofilter internal water storage was able to recover transpiration to well-watered levels after repeated droughts, while C. viminalis experienced reduced recovery ability. It is recommended all biofilters planted with trees should have internal water storage. In systems with lower moisture availability a species with more stomatal control, such as A. flexuosa, is recommended. If selecting a species with less stomatal control, such as C. viminalis, the internal water storage volume needs to be increased to avoid drought stress.
    MeSH term(s) Trees/metabolism ; Water/metabolism ; Droughts ; Drought Resistance ; Plant Leaves/metabolism
    Chemical Substances Water (059QF0KO0R)
    Language English
    Publishing date 2023-06-10
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2023.164762
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  10. Article ; Online: Cardiovascular reactivity to acute psychological stress is associated with generalized self-efficacy and self-efficacy outcomes during adventure challenges.

    Tyne, William P / Fletcher, David / Stevinson, Clare / Paine, Nicola J

    Psychophysiology

    2024  , Page(s) e14540

    Abstract: Outdoor adventure challenges are commonly used to enhance self-efficacy, but the physiological mechanisms involved remain unexplored. Additionally, while studies have documented the influence of self-efficacy on stress management, general self-efficacy ... ...

    Abstract Outdoor adventure challenges are commonly used to enhance self-efficacy, but the physiological mechanisms involved remain unexplored. Additionally, while studies have documented the influence of self-efficacy on stress management, general self-efficacy has yet to be fully understood in the context of cardiovascular stress reactivity (CVR). This study investigated the influence of self-efficacy beliefs on CVR during acute psychological stress tasks. Additionally, it explored whether CVR serves as a novel mechanism underlying the outcomes of outdoor adventure challenges. As part of a wider randomized controlled trial, participants (n = 55) were invited to complete a laboratory session to assess CVR to an active (paced auditory serial addition test (PASAT)) and a passive (cold pressor test (CPT)) stress task. Randomized participants (n = 33) to the experimental condition also engaged in a high ropes challenge course after the laboratory session. It was found that greater self-reported self-efficacy was associated with larger CVR during the CPT and positively associated with perceived engagement and performance during the PASAT. Secondly, participants reporting positive change in self-efficacy post-intervention were associated with greater CVR and greater CVR was associated with higher ratings of intervention engagement and perceived challenge. This study provides preliminary evidence suggesting that greater efficacy beliefs may heighten CVR to passive acute psychological stressors. Habitual stress reactivity may represent a novel mechanism involved in outdoor and adventure-based interventions. Future research should continue to explore the impact of psychological variables on stress physiology and examine CVR as a potential mechanism in adventure experiences.
    Language English
    Publishing date 2024-02-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209486-1
    ISSN 1540-5958 ; 0048-5772
    ISSN (online) 1540-5958
    ISSN 0048-5772
    DOI 10.1111/psyp.14540
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