Elucidation of divergent desaturation pathways in the formation of vinyl isonitrile and isocyanoacrylate

Two different types of desaturations are employed by iron- and 2-oxoglutarate-dependent (Fe/2OG) enzymes to construct vinyl isonitrile and isocyanoacrylate moieties found in isonitrile-containing natural products. A substrate-bound protein structure reveals a plausible strategy to affect desaturation and hints at substrate promiscuity of these enzymes. Analogs are synthesized and used as mechanistic probes to validate structural observations. Instead of proceeding through hydroxylated intermediate as previously proposed, a plausible carbocation species is utilized to trigger C=C bond installation. These Fe/2OG enzymes can also accommodate analogs with opposite chirality and different functional groups including isonitrile-(D)-tyrosine, N-formyl tyrosine, and phloretic acid, while maintaining the reaction selectivity.

While canonical oxygen-rebound pathway has been utilized by several Fe/2OG enzymes, insights into the desaturation process remain to be elucidated. Here, the authors suggest that a carbocation might be deployed to enable chemically divergent desaturations through decarboxylation and deprotonation.

Striatal dopamine synthesis capacity and its association with negative symptoms upon resolution of positive symptoms in first-episode schizophrenia and delusional disorder

RATIONALE

How striatal dopamine synthesis capacity (DSC) contributes to the pathogenesis of negative symptoms in first-episode schizophrenia (SZ) and delusional disorder (DD) has seldom been explored. As negative symptoms during active psychotic episodes can be complicated by secondary influences, such as positive symptoms, longitudinal investigations may help to clarify the relationship between striatal DSC and negative symptoms and differentiate between primary and secondary negative symptoms.

OBJECTIVE

A longitudinal study was conducted to examine whether baseline striatal DSC would be related to negative symptoms at 3 months in first-episode SZ and DD patients.

METHODS

Twenty-three first-episode age- and gender-matched patients (11 DD and 12 SZ) were consecutively recruited through an early intervention service for psychosis in Hong Kong. Among them, 19 (82.6%) patients (9 DD and 10 SZ) were followed up at 3 months. All patients received an ¹⁸F-DOPA PET/MR scan at baseline.

RESULTS

Baseline striatal DSC (K^occ;30-60) was inversely associated with negative symptoms at 3 months in first-episode SZ patients (r_s =  - 0.80, p = 0.010). This association remained in SZ patients even when controlling for baseline negative, positive, and depressive symptoms, as well as cumulative antipsychotic dosage (β =  - 0.69, p = 0.012). Such associations were not observed in first-episode DD patients. Meanwhile, the severity of negative symptoms at 3 months was associated with more positive symptoms in DD patients (r_s = 0.74, p = 0.010) and not in SZ patients.

CONCLUSIONS

These findings highlight the role of striatal DSC in negative symptoms upon resolution of active psychotic episodes among first-episode SZ patients. Baseline striatal dopamine activity may inform future symptom expression with important treatment implications.

Deciphering the Reaction Pathway of Mononuclear Iron Enzyme-Catalyzed N≡C Triple Bond Formation in Isocyanide Lipopeptide and Polyketide Biosynthesis

Despite the diversity of reactions catalyzed by 2-oxoglutarate-dependent nonheme iron (Fe/2OG) enzymes identified in recent years, only a limited number of these enzymes have been investigated in mechanistic detail. In particular, several Fe/2OG-dependent enzymes capable of catalyzing isocyanide formation have been reported. While the glycine moiety has been identified as a biosynthon for the isocyanide group, how the actual conversion is effected remains obscure. To elucidate the catalytic mechanism, we characterized two previously unidentified (AecA and AmcA) along with two known (ScoE and SfaA) Fe/2OG-dependent enzymes that catalyze N≡C triple bond installation using synthesized substrate analogues and potential intermediates. Our results indicate that isocyanide formation likely entails a two-step sequence involving an imine intermediate that undergoes decarboxylation-assisted desaturation to yield the isocyanide product. Results obtained from the in vitro experiments are further supported by mutagenesis, the product-bound enzyme structure, and in silico analysis.

Identification of Cyclopropane Formation in the Biosyntheses of Hormaomycins and Belactosins: Sequential Nitration and Cyclopropanation by Metalloenzymes

Hormaomycins and belactosins are peptide natural products that contain unusual cyclopropane moieties. Bioinformatics analysis of the corresponding biosynthetic gene clusters showed that two conserved genes, hrmI/belK and hrmJ/belL, were potential candidates for catalyzing cyclopropanation. Using in vivo and in vitro assays, the functions of HrmI/BelK and HrmJ/BelL were established. HrmI and BelK, which are heme oxygenase-like dinuclear iron enzymes, catalyze oxidation of the ϵ-amino group of l-lysine to afford l-6-nitronorleucine. Subsequently, HrmJ and BelL, which are iron- and α-ketoglutarate-dependent oxygenases, effectively convert l-6-nitronorleucine into 3-(trans-2-nitrocyclopropyl)-alanine through C4-C6 bond installation. These observations disclose a novel pathway of cyclopropane ring construction and exemplify the new chemistry involving metalloenzymes in natural product biosynthesis.

BesC Initiates C-C Cleavage through a Substrate-Triggered and Reactive Diferric-Peroxo Intermediate

BesC catalyzes the iron- and O₂-dependent cleavage of 4-chloro-l-lysine to form 4-chloro-l-allylglycine, formaldehyde, and ammonia. This process is a critical step for a biosynthetic pathway that generates a terminal alkyne amino acid which can be leveraged as a useful bio-orthogonal handle for protein labeling. As a member of an emerging family of diiron enzymes that are typified by their heme oxygenase-like fold and a very similar set of coordinating ligands, recently termed HDOs, BesC performs an unusual type of carbon-carbon cleavage reaction that is a significant departure from reactions catalyzed by canonical dinuclear-iron enzymes. Here, we show that BesC activates O₂ in a substrate-gated manner to generate a diferric-peroxo intermediate. Examination of the reactivity of the peroxo intermediate with a series of lysine derivatives demonstrates that BesC initiates this unique reaction trajectory via cleavage of the C4-H bond; this process represents the rate-limiting step in a single turnover reaction. The observed reactivity of BesC represents the first example of a dinuclear-iron enzyme that utilizes a diferric-peroxo intermediate to capably cleave a C-H bond as part of its native function, thus circumventing the formation of a high-valent intermediate more commonly associated with substrate monooxygenations.

Mental Health Risks after Repeated Exposure to Multiple Stressful Events during Ongoing Social Unrest and Pandemic in Hong Kong: The Role of Rumination: Risques pour la santé mentale après une exposition répétée à de multiples événements stressants d'agitation sociale durable et de pandémie à Hong Kong: le rôle de la rumination

OBJECTIVES

The co-occurrence of different classes of population-level stressors, such as social unrest and public health crises, is common in contemporary societies. Yet, few studies explored their combined mental health impact. The aim of this study was to examine the impact of repeated exposure to social unrest-related traumatic events (TEs), coronavirus disease 2019 (COVID-19) pandemic-related events (PEs), and stressful life events (SLEs) on post-traumatic stress disorder (PTSD) and depressive symptoms, and the potential mediating role of event-based rumination (rumination of TEs-related anger, injustice, guilt, and insecurity) between TEs and PTSD symptoms.

METHODS

Community members in Hong Kong who had utilized a screening tool for PTSD and depressive symptoms were invited to complete a survey on exposure to stressful events and event-based rumination.

RESULTS

A total of 10,110 individuals completed the survey. Hierarchical regression analysis showed that rumination, TEs, and SLEs were among the significant predictors for PTSD symptoms (all P < 0.001), accounting for 32% of the variance. For depression, rumination, SLEs, and PEs were among the significant predictors (all P < 0.001), explaining 24.9% of the variance. Two-way analysis of variance of different recent and prior TEs showed significant dose-effect relationships. The effect of recent TEs on PTSD symptoms was potentiated by prior TEs (P = 0.005). COVID-19 PEs and prior TEs additively contributed to PTSD symptoms, with no significant interaction (P = 0.94). Meanwhile, recent TEs were also potentiated by SLEs (P = 0.002). The effects of TEs on PTSD symptoms were mediated by rumination (β = 0.38, standard error = 0.01, 95% confidence interval: 0.36 to 0.41), with 40.4% of the total effect explained. All 4 rumination subtypes were significant mediators.

CONCLUSIONS

Prior and ongoing TEs, PEs, and SLEs cumulatively exacerbated PTSD and depressive symptoms. The role of event-based rumination and their interventions should be prioritized for future research.

Prospective prediction of PTSD and depressive symptoms during social unrest and COVID-19 using a brief online tool

Large-scale protracted population stressors, such as social unrest and the coronavirus disease 2019 (COVID-19), are associated with increased symptoms of post-traumatic stress disorder (PTSD) and depression. Cost-effective mental health screening is prerequisite for timely intervention. We developed an online tool to identify prospective predictors of PTSD and depressive symptoms in the context of co-occurring social unrest and COVID-19 in Hong Kong. 150 participants completed baseline and follow-up assessments, with a median duration of 29 days. Three logistic regression models were constructed to assess its discriminative power in predicting PTSD and depressive symptoms at one month. Receiver-operating characteristic analysis was performed for each model to determine their optimal decision thresholds. Sensitivity and specificity of the models were 87.1% and 53.8% for probable PTSD, 77.5% and 63.3% for high-risk depressive symptoms, and 44.7% and 96.4% for no significant depressive symptoms. The models performed well in discriminating outcomes (AUCs range: 0.769-0.811). Probable PTSD was predicted by social unrest-related traumatic events, high rumination, and low resilience. Rumination and resilience also predicted high-risk and no significant depressive symptoms, with COVID-19-related events also predicting no significant depression risk. Accessible screening of probable mental health outcomes with good predictive capability may be important for early intervention opportunities.

Induced ideas of reference during social unrest and pandemic in Hong Kong

Ideas of reference (IOR) are often implicated in predicting psychosis onset. They have been conceptualized to present on a continuum, from oversensitive psychological reactions to delusional thoughts. It is however unknown to what extent IOR may be triggered by collective environmental stress. We obtained timely data from 9873 individuals to assess IOR in relation to trauma exposure in the 2019-2020 social unrest in Hong Kong. Two levels of IOR are distinguished: attenuated IOR (IOR-A), being the experience of feeling particularly referred to within a group; and exclusive IOR (IOR-E), the experience of feeling exclusively referred to while others are not. Logistic regressions showed that event-based rumination was a shared predictor for IOR-A (OR = 1.07, CI = 1.03-1.10) and IOR-E (OR = 1.09, CI = 1.02-1.17). For IOR-A, three categories of social unrest-related traumatic events (TEs) were significant predictors, including being attacked or having experienced sexual violence (OR = 4.14, CI = 1.93-8.85), being arrested (OR = 4.48, CI = 1.99-10.10), and being verbally abused (OR = 2.66, CI = 1.28-5.53). Being arrested was significant for IOR-E (OR = 3.87, CI = 1.03-14.52), though not when rumination was included. Education level also significantly predicted IOR-E (OR = 0.72, CI = 0.52-0.99). Further analysis revealed that rumination significantly mediated between TEs and IOR severity (β = 0.26, SE = 0.01, CI = 0.24-0.28). The findings are consistent with the hypothesis that IOR-A and IOR-E occur as levels on a continuum, but each has some distinctive correlates. Extrinsic events may play a more prominent role in IOR-A, while intrinsic factors, such as cognitive capacity, may play a more prominent role in IOR-E. The involvement of rumination across the IOR spectrum suggests an opportunity for intervention.

Current Understanding toward Isonitrile Group Biosynthesis and Mechanism

Isonitrile group has been identified in many natural products. Due to the broad reactivity of N≡C triple bond, these natural products have valuable pharmaceutical potentials. This review summarizes the current biosynthetic pathways and the corresponding enzymes that are responsible for isonitrile-containing natural product generation. Based on the strategies utilized, two fundamentally distinctive approaches are discussed. In addition, recent progress in elucidating isonitrile group formation mechanisms is also presented.

Abnormal cognitive effort allocation and its association with amotivation in first-episode psychosis

BACKGROUND

Abnormal effort-based decision-making represents a potential mechanism underlying motivational deficits (amotivation) in psychotic disorders. Previous research identified effort allocation impairment in chronic schizophrenia and focused mostly on physical effort modality. No study has investigated cognitive effort allocation in first-episode psychosis (FEP).

METHOD

Cognitive effort allocation was examined in 40 FEP patients and 44 demographically-matched healthy controls, using Cognitive Effort-Discounting (COGED) paradigm which quantified participants' willingness to expend cognitive effort in terms of explicit, continuous discounting of monetary rewards based on parametrically-varied cognitive demands (levels N of N-back task). Relationship between reward-discounting and amotivation was investigated. Group differences in reward-magnitude and effort-cost sensitivity, and differential associations of these sensitivity indices with amotivation were explored.

RESULTS

Patients displayed significantly greater reward-discounting than controls. In particular, such discounting was most pronounced in patients with high levels of amotivation even when N-back performance and reward base amount were taken into consideration. Moreover, patients exhibited reduced reward-benefit sensitivity and effort-cost sensitivity relative to controls, and that decreased sensitivity to reward-benefit but not effort-cost was correlated with diminished motivation. Reward-discounting and sensitivity indices were generally unrelated to other symptom dimensions, antipsychotic dose and cognitive deficits.

CONCLUSION

This study provides the first evidence of cognitive effort-based decision-making impairment in FEP, and indicates that decreased effort expenditure is associated with amotivation. Our findings further suggest that abnormal effort allocation and amotivation might primarily be related to blunted reward valuation. Prospective research is required to clarify the utility of effort-based measures in predicting amotivation and functional outcome in FEP.

Perspective on medication decisions following remission from first-episode psychosis

While antipsychotics (APs) could provide rapid relief of positive symptoms in psychotic disorders, their usage is often associated with side effects, stigma and inconveniences. For these and other reasons, many psychosis patients, particularly those of first-episode psychosis (FEP) in remission, wish to discontinue maintenance treatment. The current review aims to discuss the strategies of AP treatment following remission from FEP, with particular emphasis on the evaluation of outcomes following AP discontinuation. Upon review of relevant literature, three potential strategies are put forth for treatment-responsive, remitted FEP patients: a) life-long maintenance treatment, b) AP discontinuation during second year of treatment, or c) AP discontinuation after three years of treatment. In theory, the first strategy presents the safest option for maximal symptom control. However, a rigorous RCT indicates that if AP discontinuation is to be attempted, the third strategy best prevents poor long-term clinical outcomes. Further data is needed to address the costs and benefits of each treatment strategy, compare AP-free patients with those on different types of APs, as well as explore even longer-term outcomes.

Inter-relationships among psychopathology, premorbid adjustment, cognition and psychosocial functioning in first-episode psychosis: a network analysis approach

BACKGROUND

Better understanding of interplay among symptoms, cognition and functioning in first-episode psychosis (FEP) is crucial to promoting functional recovery. Network analysis is a promising data-driven approach to elucidating complex interactions among psychopathological variables in psychosis, but has not been applied in FEP.

METHOD

This study employed network analysis to examine inter-relationships among a wide array of variables encompassing psychopathology, premorbid and onset characteristics, cognition, subjective quality-of-life and psychosocial functioning in 323 adult FEP patients in Hong Kong. Graphical Least Absolute Shrinkage and Selection Operator (LASSO) combined with extended Bayesian information criterion (BIC) model selection was used for network construction. Importance of individual nodes in a generated network was quantified by centrality analyses.

RESULTS

Our results showed that amotivation played the most central role and had the strongest associations with other variables in the network, as indexed by node strength. Amotivation and diminished expression displayed differential relationships with other nodes, supporting the validity of two-factor negative symptom structure. Psychosocial functioning was most strongly connected with amotivation and was weakly linked to several other variables. Within cognitive domain, digit span demonstrated the highest centrality and was connected with most of the other cognitive variables. Exploratory analysis revealed no significant gender differences in network structure and global strength.

CONCLUSION

Our results suggest the pivotal role of amotivation in psychopathology network of FEP and indicate its critical association with psychosocial functioning. Further research is required to verify the clinical significance of diminished motivation on functional outcome in the early course of psychotic illness.

Search for η^{'} Bound Nuclei in the ^{12}C(γ,p) Reaction with Simultaneous Detection of Decay Products

We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}N→ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ_{lab}^{ηp}<-0.9 was obtained to be 2.2  nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η^{'} production rate. Our results indicate a small branching fraction of the η^{'}N→ηN process and/or a shallow η^{'}-nucleus potential.

[Integrated bioinformatics analysis of key genes in allergic rhinitis]

Objective: To obtain biomarkers of allergic rhinitis (AR) by performing bioinformatics analysis on gene chips related to allergic rhinitis in the Gene Expression Database (GEO). Methods: From June 2018 to December 2019, we downloaded data (GSE46171) involving 3 control individuals and 6 AR patients from the publicallyavailable Gene Expression Omnibus database (GEO,http://www.ncbi.nlm.nih.gov/geo), and differentially expressed genes (DEGs) were screened between AR and normal tissues by using the GEO2R online tool comprehensively. Then, we used the bioinformatics methods, including Gene Ontology (GO) analysis and Kyoto Encyclopedia of Gene, Genome (KEGG) pathway analysis and protein-protein interaction (PPI) network construction to identify key genes in AR. In the same period, the inferior turbinate mucosa tissues of 15 AR patients and 15 healthy controls were collected during operationinthe Department of Otolaryngology Head and Neck Surgery of the People 's Hospital of Wuhan Universityto further verify important genes and pathways and perform real-time quantitative PCR.SPSS9.0 statistical software was used for statistical analysis. Results: Two hundred and seventeen DEGs genes were selected, of which 112 were down-regulated genes and 105 were up-regulated genes. Among them, the five up-regulated genes with the most significant differences were KLK7, TMPRSS11A, SPRR2C, TPSAB1, and TXLNGY; the five down-regulated genes with the most significant differences were: XIST, CTAG1A, PRB1, CXCL11 and PRB2. By constructing a PPI network among 217 DEGs, the 15 hub genes obtained were IFIH1, CCR2, CD80, TLR7, EIF1AY, DDX3Y, RSAD2, RPS4Y2, RPS4Y1, XAF1, KDM5D, ZFY, NLGN4Y, IFIT5 and DDX60L, these Genes were at a hub in a gene network. We collected inferior turbinate mucosa tissue during surgery,and these 15 genes were verified, and the expressions of IFIH1, CCR2, CD80, TLR7, RSAD2, XAF1, IFIT5 and DDX60L were reduced, wherea the expressions of EIF1AY, DDX3Y, RPS4Y2, RPS4Y1, KDM5D, ZFY and NLGN4Y were increased, differences were statistically significant (all P<0.05). Conclusions: The study finds 217 genes closely related to allergic rhinitis and obtains 15 hub genes through the PPI network. These genes may be involved in the pathogenesis of allergic rhinitis and are expected to become new biomarkers for allergic rhinitis.

Mortality Risk Associated with Haloperidol Use Compared with Other Antipsychotics: An 11-Year Population-Based Propensity-Score-Matched Cohort Study

BACKGROUND

Haloperidol remains a frequently prescribed first-generation antipsychotic. However, haloperidol-associated mortality risk by all causes, cardiovascular disease (CVD), and pneumonia compared with other antipsychotics is unknown.

OBJECTIVE

This study investigated the mortality risk associated with long-term haloperidol treatment versus that with other antipsychotics.

METHODS

We identified incident antipsychotic users from 2004 to 2014 in the Clinical Data Analysis and Reporting System (CDARS), a population-based clinical database managed by the Hong Kong Hospital Authority. We included patients who were aged ≥ 18 and received antipsychotics for any indication apart from terminal illnesses or management of acute behavioural disturbance. Patients on haloperidol and other antipsychotic agents (risperidone, quetiapine, olanzapine, chlorpromazine, aripiprazole, sulpiride, amisulpride, or trifluoperazine) were matched by propensity score. Hazard ratios (HRs) for all-cause mortality and death due to CVD and pneumonia were estimated with 95% confidence intervals (CIs) using a Cox proportional hazards model.

RESULTS

In total, 136,593 users of antipsychotics were included. During a mean follow-up of 3.2 years, the incidence of all-cause mortality ranged from 186.8/1000 person-years for haloperidol to 10.4/1000 person-years for trifluoperazine. The risk of all-cause mortality was lower with non-haloperidol antipsychotics than with haloperidol, with HRs ranging from 0.68 (95% CI 0.64-0.72 [chlorpromazine]) to 0.43 (95% CI 0.36-0.53 [trifluoperazine]). Risperidone, quetiapine, sulpiride, chlorpromazine, aripiprazole, and trifluoperazine were associated with a significantly lower risk of pneumonia-related mortality. A significantly lower risk of CVD mortality was observed for risperidone, sulpiride, chlorpromazine, and quetiapine.

CONCLUSION

Haloperidol was associated with increased overall mortality when compared with other antipsychotics in long-term follow-up. Treatment with haloperidol should be carefully considered, especially in older patients and patients at risk of CVD or pneumonia, since the risk of death appears to be lower with non-haloperidol agents.

P282 Elevated serum uric acid associated with both electrocardiographic and echocardiographic left ventricular hypertrophy independent of blood pressure in healthy individuals

Funding Acknowledgements

TSGH 108-11

Background

Elevated serum uric acid (SUA) is associated with cardiac fibrosis and hypertrophy. A growing body of evidence showed the positive correlation between hyperuricemia (HUA) and left ventricular hypertrophy (LVH), but most studies defined LVH by a single method such as electrocardiogram or echocardiogram; the former is generally used in massive screen but the latter take advantage of the accuracy of LVH.

Purpose

We conducted this study to concomitantly investigate the association between SUA and electrocardiographic and echocardiographic LVH.

Methods

We initially enrolled 17,913 healthy individuals, who routinely underwent an annual health exam at our hospital between 2016/1/1∼2016/12/31. Of them, 347 individuals received transthoracic echocardiography because of abnormal results in their electrocardiogram. Amplitudes of 12-lead electrocardiogram were artificially measured by a study assistant under the supervision and by artificial intelligence. HUA is defined as an SUA level of ≥7 mg/dl in men and ≥6 mg/dl in women. Electrocardiographic LVH is defined by the criteria of Cornel voltage and product and Sokolow-Lyon and the Minnesota Code ECG classification. Echocardiographic LVH is defined by LV mass index ≥115g/m² in men or ≥95g/m² in women.

Results

The HUA group (n = 233) vs. normouricemic group (n = 114) was older and predominant male with greater values of body mass index, systolic and diastolic blood pressure and laboratory biomarkers, including non-high density total cholesterol, fasting glucose impairment, creatinine clearance, and haemoglobin. The two groups had comparable lifestyle choices, including tobacco use, alcohol intake, and physical activities per week. The HUA group compared with the normouricemic group had greater values of S amplitude of V1 plus R amplitude of V5 (3031 ± 2055 uV vs. 2566 ± 1021 uV, P = 0.005), R amplitude in lead I plus S amplitude in lead III (842 ± 443 uV vs. 696 ± 386 uV, P = 0.002) and LV mass index (95 ± 23 g/m² vs. 85 ± 30 g/m², P = 0.001). The prevalence of electrocardiographic and echocardiographic LVH was greater in the HUA group than the normouricemic group (7.0% vs. 2.1%, P = 0.034 for electrocardiographic LVH and 15.8% vs. 7.7%, P = 0.025 for echocardiographic LVH). In multivariate logistic regression analyses, elevated SUA was associated with LVH after the confounders were fully adjusted (OR: 1.38, 95% CI: 1.07-1.77, P = 0.012 for electrocardiographic LVH and OR: 1.58, 95% CI 1.15-2.17, P = 0.004 for echocardiographic LVH).

Conclusion

Elevated SUA is independently associated with the prevalence of both electrocardiographic and echocardiographic LVH in healthy individuals from Taiwan. Future studies might evaluate urate-lowering effects on the regression of LVH.

Predicting first-episode psychosis patients who will never relapse over 10 years

BACKGROUND

Although relapse in psychosis is common, a small proportion of patients will not relapse in the long term. We examined the proportion and predictors of patients who never relapsed in the 10 years following complete resolution of positive symptoms from their first psychotic episode.

METHOD

Patients who previously enrolled in a 12-month randomized controlled trial on medication discontinuation and relapse following first-episode psychosis (FEP) were followed up after 10 years. Relapse of positive symptoms was operationalized as a change from a Clinical Global Impression scale positive score of <3 for at least 3 consecutive months to a score of ⩾3 (mild or more severe). Baseline predictors included basic demographics, premorbid functioning, symptoms, functioning, and neurocognitive functioning.

RESULTS

Out of 178 first-episode patients, 37 (21%) never relapsed during the 10-year period. Univariate predictors (p ⩽ 0.1) of patients who never relapsed included a duration of untreated psychosis (DUP) ⩽30 days, diagnosed with non-schizophrenia spectrum disorders, having less severe negative symptoms, and performing better in logical memory immediate recall and verbal fluency tests. A multivariate logistic regression analysis further suggested that the absence of any relapsing episodes was significantly related to better short-term verbal memory, shorter DUP, and non-schizophrenia spectrum disorders.

CONCLUSIONS

Treatment delay and neurocognitive function are potentially modifiable predictors of good long-term prognosis in FEP. These predictors are informative as they can be incorporated into an optimum risk prediction model in the future, which would help with clinical decision making regarding maintenance treatment in FEP.

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3  GeV/c) direct-photon yields from Au+Au collisions at sqrt[s_{NN}]=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrt[s_{NN}]=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1  GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5  GeV/c), but when results from different collision energies are compared, an additional sqrt[s_{NN}]-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

A New Microbial Pathway for Organophosphonate Degradation Catalyzed by Two Previously Misannotated Non-Heme-Iron Oxygenases

The assignment of biochemical functions to hypothetical proteins is challenged by functional diversification within many protein structural superfamilies. This diversification, which is particularly common for metalloenzymes, renders functional annotations that are founded solely on sequence and domain similarities unreliable and often erroneous. Definitive biochemical characterization to delineate functional subgroups within these superfamilies will aid in improving bioinformatic approaches for functional annotation. We describe here the structural and functional characterization of two non-heme-iron oxygenases, TmpA and TmpB, which are encoded by a genomically clustered pair of genes found in more than 350 species of bacteria. TmpA and TmpB are functional homologues of a pair of enzymes (PhnY and PhnZ) that degrade 2-aminoethylphosphonate but instead act on its naturally occurring, quaternary ammonium analogue, 2-(trimethylammonio)ethylphosphonate (TMAEP). TmpA, an iron(II)- and 2-(oxo)glutarate-dependent oxygenase misannotated as a γ-butyrobetaine (γbb) hydroxylase, shows no activity toward γbb but efficiently hydroxylates TMAEP. The product, ( R)-1-hydroxy-2-(trimethylammonio)ethylphosphonate [( R)-OH-TMAEP], then serves as the substrate for the second enzyme, TmpB. By contrast to its purported phosphohydrolytic activity, TmpB is an HD-domain oxygenase that uses a mixed-valent diiron cofactor to enact oxidative cleavage of the C-P bond of its substrate, yielding glycine betaine and phosphate. The high specificities of TmpA and TmpB for their N-trimethylated substrates suggest that they have evolved specifically to degrade TMAEP, which was not previously known to be subject to microbial catabolism. This study thus adds to the growing list of known pathways through which microbes break down organophosphonates to harvest phosphorus, carbon, and nitrogen in nutrient-limited niches.

Gender differences in correlates of cognition in first-episode psychosis

Studies of gender cognitive differences in schizophrenia have reported mixed results. This study examined cognitive correlates including demographics, symptoms and functioning in men and women in a large sample of first-episode adult-onset psychosis patients. Detailed demographic, clinical and functioning data were collected from 360 first-episode patients upon admission into an early intervention service for psychotic disorders. They were also administered a comprehensive neurocognitive battery. Correlation analyses showed that memory and working memory were more significantly associated with onset age, negative symptoms and side effects in women. Processing speed correlated with antipsychotic dosage in men and side effects in women. Selective attention correlated with reality distortion and negative symptoms in women, and onset age and education in men. Executive function correlated with onset age and reality distortion in women. All cognitive domains significantly correlated with educational level and functioning in both genders. Negative symptoms explained significant variability in cognition in both genders, while reality distortion, side effects and affective symptoms were significant factors that differentiated between genders. Although there are similarities in cognitive deficits, considerable heterogeneity exists in associations of symptoms and cognition in men and women. Results facilitate individualised tailoring of interventions, including cognitive remediation therapy.

Differential Cross Section and Photon-Beam Asymmetry for the γ[over →]p → π^{-}Δ^{++}(1232) Reaction at Forward π^{-} Angles for E_{γ}=1.5-2.95 GeV

Differential cross sections and photon-beam asymmetries for the γ[over →]p→π^{-}Δ^{++}(1232) reaction have been measured for 0.7<cosθ_{π}^{c.m.}<1 and E_{γ}=1.5-2.95  GeV at SPring-8/LEPS. The first-ever high statistics cross-section data are obtained in this kinematical region, and the asymmetry data for 1.5<E_{γ}(GeV)<2.8 are obtained for the first time. This reaction has a unique feature for studying the production mechanisms of a pure uu[over ¯] quark pair in the final state from the proton. Although there is no distinct peak structure in the cross sections, a non-negligible excess over the theoretical predictions is observed at E_{γ}=1.5-1.8  GeV. The asymmetries are found to be negative in most of the present kinematical regions, suggesting the dominance of π exchange in the t channel. The negative asymmetries at forward meson production angles are different from the asymmetries previously measured for the photoproduction reactions producing a dd[over ¯] or an ss[over ¯] quark pair in the final state. Advanced theoretical models introducing nucleon resonances and additional unnatural-parity exchanges are needed to reproduce the present data.

Chinese label for people at risk for psychosis

AIM

With the movement of early detection and intervention for people at risk for psychosis, there is a growing need for a uniform terminology to describe the condition. A diagnostic label that can adapt into local culture and value may have positive effect in minimizing stigma. This study explored the preference of Chinese label for people at risk of psychosis and its associated stigma in Hong Kong.

METHODS

A total of 149 individuals from the general public and 51 health-care professionals were recruited between March 2013 and May 2014. The condition of at risk for psychosis was described in a vignette. Participants' preference of label and perceived stigma of the condition and their basic demographics were collected by self-administered questionnaires.

RESULTS

The most preferred Chinese label was 'yun-niang-qi' (developing period, 45%), followed by 'qian-qu-qi' (precursor period, 19%), 'feng-xian-qi' (risky period, 18%), 'zao-xian-qi' (early sign period, 16%) and 'gao-wei-qi' (high risk period, 4%). Gender, age, occupation and previous contact with mental health were not associated with preference of any Chinese label.

CONCLUSIONS

The process in searching for this potential and locally accepted label for people at risk for psychosis has raised the awareness among the professionals. A proper label may help promote future clinical research and mental health services in Hong Kong.

Relationship of amotivation to neurocognition, self-efficacy and functioning in first-episode psychosis: a structural equation modeling approach

BACKGROUND

Better understanding of the complex interplay among key determinants of functional outcome is crucial to promoting recovery in psychotic disorders. However, this is understudied in the early course of illness. We aimed to examine the relationships among negative symptoms, neurocognition, general self-efficacy and global functioning in first-episode psychosis (FEP) patients using structural equation modeling (SEM).

METHOD

Three hundred and twenty-one Chinese patients aged 26-55 years presenting with FEP to an early intervention program in Hong Kong were recruited. Assessments encompassing symptom profiles, functioning, perceived general self-efficacy and a battery of neurocognitive tests were conducted. Negative symptom measurement was subdivided into amotivation and diminished expression (DE) domain scores based on the ratings in the Scale for the Assessment of Negative Symptoms.

RESULTS

An initial SEM model showed no significant association between functioning and DE which was removed from further analysis. A final trimmed model yielded very good model fit (χ2 = 15.48, p = 0.63; comparative fit index = 1.00; root mean square error of approximation <0.001) and demonstrated that amotivation, neurocognition and general self-efficacy had a direct effect on global functioning. Amotivation was also found to mediate a significant indirect effect of neurocognition and general self-efficacy on functioning. Neurocognition was not significantly related to general self-efficacy.

CONCLUSION

Our results indicate a critical intermediary role of amotivation in linking neurocognitive impairment to functioning in FEP. General self-efficacy may represent a promising treatment target for improvement of motivational deficits and functional outcome in the early illness stage.

Validation of the Chinese Version of the Revised Clinical Interview Schedule: Findings from Hong Kong Mental Morbidity Survey

This study aimed to assess the psychometric properties of the Chinese version of the Revised Clinical Interview Schedule (C-CIS-R), and explore its applicability as a diagnostic instrument for common mental disorders (CMDs) in Hong Kong. Its psychometric properties were evaluated among 140 patients and 161 healthy controls. In comparison to the diagnoses made by the Structured Clinical Interview for the DSM-IV, the C-CIS-R showed good criterion validity in diagnosing CMDs. The correlation of the total score of C-CIS-R with the 12-item General Health Questionnaire and Hospital Anxiety and Depression Scale was satisfactory, indicating favourable convergent validity as well. The inter-rater and test-retest reliability were also satisfactory. Receiver operating characteristic analyses suggested an optimal cut-off point of 11/12 for detecting diagnosable CMDs (sensitivity: 0.69; specificity: 0.93) and 17/18 for identifying a need for treatment (sensitivity: 0.70; specificity: 0.95). In conclusion, C-CIS-R is a valid diagnostic instrument for CMDs in a Chinese community. Its cut-off points for clinically significant symptoms and treatment needs among Chinese are identical to those adopted in the original English version.

Prediction of motivational impairment: 12-month follow-up of the randomized-controlled trial on extended early intervention for first-episode psychosis

BACKGROUND

Amotivation is prevalent in first-episode psychosis (FEP) patients and is a major determinant of functional outcome. Prediction of amotivation in the early stage of psychosis, however, is under-studied. We aimed to prospectively examine predictors of amotivation in FEP patients in a randomized-controlled trial comparing a 1-year extension of early intervention (Extended EI, 3-year EI) with step-down psychiatric care (SC, 2-year EI).

METHODS

One hundred sixty Chinese patents were recruited from a specialized EI program for FEP in Hong Kong after they have completed this 2-year EI service, randomly allocated to Extended EI or SC, and followed up for 12 months. Assessments on premorbid adjustment, onset profiles, baseline symptom severity and treatment characteristics were conducted. Data analysis was based on 156 subjects who completed follow-up assessments.

RESULTS

Amotivation at 12-month follow-up was associated with premorbid adjustment, allocated treatment condition, and levels of positive symptoms, disorganization, amotivation, diminished expression (DE) and depression at study intake. Hierarchical multiple regression analysis revealed that Extended EI and lower levels of DE independently predicted better outcome on 12-month amotivation.

CONCLUSION

Our findings indicate a potentially critical therapeutic role of an extended specialized EI on alleviating motivational impairment in FEP patients. The longer-term effect of Extended EI on amotivation merits further investigation.

Quality of life and functioning in first-episode psychosis Chinese patients with different antipsychotic medications

AIM

This study compared the quality of life and functioning of 285 first-episode psychosis Chinese patients with different antipsychotic medications in Hong Kong.

METHOD

Under the Jockey Club Early Psychosis project, a total of 285 patients were recruited from all inpatient and outpatient psychiatric units in Hong Kong between 2009 and 2011. In addition to the medication information, patients were assessed with the Scale for the Assessment of Positive Symptoms, the Scale for the Assessment of Negative Symptoms, the Udvalg for Kliniske Undersøgelser (UKU), Barnes Akathisia Rating Scale (BARS), the Social and Occupational Functioning Assessment Scale (SOFAS), the Role Functioning Scale, and the Medical Outcomes Study Short Form 12-Item Health Survey (SF-12) after stabilization of mental condition. Differences between individual antipsychotic medications were compared using anova and multinomial regression model.

RESULTS

The results demonstrated significant differences between different antipsychotic medications in the mean of UKU neurological subscore, BARS total score, SOFAS score and SF-12 Mental Component Summary (MCS) score. Patients with haloperidol had higher mean UKU neurological subscore than patients with olanzapine or amisulpride. Risperidone was associated with higher mean BARS total score than olanzapine, amisulpride or sulpiride. Higher mean MCS was found in patients with amisulpride than patients with risperidone.

CONCLUSIONS

The findings suggest that antipsychotics have differential associations with the quality of life and functioning in patients with first-episode psychosis. Future prospective study is warranted to investigate if patients with first-episode psychosis will benefit specific type of antipsychotics more than the others.

Visual working memory deterioration preceding relapse in psychosis

BACKGROUND

Relapse is distressingly common after the first episode of psychosis, yet it is poorly understood and difficult to predict. Investigating changes in cognitive function preceding relapse may provide new insights into the underlying mechanism of relapse in psychosis. We hypothesized that relapse in fully remitted first-episode psychosis patients was preceded by working memory deterioration.

METHOD

Visual memory and verbal working memory were monitored prospectively in a 1-year randomized controlled trial of remitted first-episode psychosis patients assigned to medication continuation (quetiapine 400 mg/day) or discontinuation (placebo). Relapse (recurrence of positive symptoms of psychosis), visual (Visual Patterns Test) and verbal (Letter-Number span test) working memory and stressful life events were assessed monthly.

RESULTS

Remitted first-episode patients (n = 102) participated in the study. Relapsers (n = 53) and non-relapsers (n = 49) had similar baseline demographic and clinical profiles. Logistic regression analyses indicated relapse was associated with visual working memory deterioration 2 months before relapse [odds ratio (OR) 3.07, 95% confidence interval (CI) 1.19-7.92, P = 0.02], more stressful life events 1 month before relapse (OR 2.11, 95% CI 1.20-3.72, P = 0.01) and medication discontinuation (OR 5.52, 95% CI 2.08-14.62, P = 0.001).

CONCLUSIONS

Visual working memory deterioration beginning 2 months before relapse in remitted first-episode psychosis patients (not baseline predictor) may reflect early brain dysfunction that heralds a psychotic relapse. The deterioration was found to be unrelated to a worsening of psychotic symptoms preceding relapse. Testable predictors offer insight into the brain processes underlying relapse in psychosis.

Spectroscopic Evidence for the Two C-H-Cleaving Intermediates of Aspergillus nidulans Isopenicillin N Synthase

The enzyme isopenicillin N synthase (IPNS) installs the β-lactam and thiazolidine rings of the penicillin core into the linear tripeptide l-δ-aminoadipoyl-l-Cys-d-Val (ACV) on the pathways to a number of important antibacterial drugs. A classic set of enzymological and crystallographic studies by Baldwin and co-workers established that this overall four-electron oxidation occurs by a sequence of two oxidative cyclizations, with the β-lactam ring being installed first and the thiazolidine ring second. Each phase requires cleavage of an aliphatic C-H bond of the substrate: the pro-S-CCys,β-H bond for closure of the β-lactam ring, and the CVal,β-H bond for installation of the thiazolidine ring. IPNS uses a mononuclear non-heme-iron(II) cofactor and dioxygen as cosubstrate to cleave these C-H bonds and direct the ring closures. Despite the intense scrutiny to which the enzyme has been subjected, the identities of the oxidized iron intermediates that cleave the C-H bonds have been addressed only computationally; no experimental insight into their geometric or electronic structures has been reported. In this work, we have employed a combination of transient-state-kinetic and spectroscopic methods, together with the specifically deuterium-labeled substrates, A[d2-C]V and AC[d8-V], to identify both C-H-cleaving intermediates. The results show that they are high-spin Fe(III)-superoxo and high-spin Fe(IV)-oxo complexes, respectively, in agreement with published mechanistic proposals derived computationally from Baldwin's founding work.

Interference Effect between ϕ and Λ(1520) Production Channels in the γp→K^{+}K^{-}p Reaction near Threshold

The ϕ-Λ(1520) interference effect in the γp→K^{+}K^{-}p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between ϕ and Λ(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K^{+}K^{-} pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the sqrt[s]=2.1  GeV bump structure in forward differential cross sections for ϕ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.

Association Between Acute Neuropsychiatric Events and Helicobacter pylori Therapy Containing Clarithromycin

IMPORTANCE

There is a concern that Helicobacter pylori therapy containing clarithromycin might be associated with acute neuropsychiatric events.

OBJECTIVE

To examine the association between H pylori therapy containing clarithromycin and acute neuropsychiatric events.

DESIGN, SETTING, AND PARTICIPANTS

A self-controlled case series study was conducted using the Clinical Data Analysis and Reporting System database in Hong Kong to explore any association. The exposure of interest was H pylori therapy containing clarithromycin in the outpatient setting. Study patients, 18 years or older at cohort entry, must have had both exposure to H pylori therapy containing clarithromycin and their first recorded neuropsychiatric events between January 1, 2003, and December 31, 2012. A post hoc nested case-control analysis was also performed in patients receiving H pylori therapy containing clarithromycin.

MAIN OUTCOMES AND MEASURES

The primary outcome was composite neuropsychiatric events, while secondary outcomes were psychotic events and cognitive impairment. Risk periods in the self-controlled case series analysis were defined as 14-day preexposure period, current use (days 1-14 since prescription start date) and recent use (days 15-30). Age-adjusted incidence rate ratios (IRR) were estimated using the conditional Poisson regression.

RESULTS

Of 66 559 patients who had at least 1 outpatient prescription of H pylori therapy containing clarithromycin. Their mean (SD) age at cohort entry was 50.8 (14.8 years); their mean age at first exposure was 55.4 (14.8) years, and 30 910 were male (46.4%). A total of 1824 patients had their first recorded composite neuropsychiatric events during the study period. An increased IRR of 4.12 (35 composite neuropsychiatric events during 72 person-years; 95% CI, 2.94-5.76) during current use was observed but not in recent use (9 events during 82 person-years; IRR, 0.95; 95% CI, 0.49-1.83) and 14-day preexposure period (14 events during 72 person-years; IRR, 1.63; 95% CI, 0.96-2.77) vs baseline (1766 events during 16 665 person-years). Similarly, both the risk of psychotic events and cognitive impairment increased during current use vs baseline, although this subsequently returned to baseline incidence levels during recent use. The crude absolute risks of composite neuropsychiatric events, psychotic events, and cognitive impairment during current use were 0.45, 0.12, and 0.12 per 1000 prescriptions, respectively. The nested case-control analysis also gave similar results to that of the self-controlled case series analysis.

CONCLUSIONS AND RELEVANCE

This study shows evidence of a short-term increased risk of neuropsychiatric events associated with H pylori therapy containing clarithromycin.

Incidence of hospitalization and its associated factors in first-episode psychosis in Hong Kong

AIM

This study examined the incidence of hospitalization and its associated factors in patients with first-episode psychosis in Hong Kong.

METHOD

From 2009 to 2011, 360 patients were recruited consecutively as part of a controlled study of an early psychosis intervention service (the Jockey Club Early Psychosis project) in Hong Kong. Demographic and clinical information were obtained from face-to-face interviews and was reconfirmed using medical records. Factors relating to hospitalization during first episode were explored.

RESULTS

The incidence of hospitalization during first-episode psychosis was 57.2%. Patients who were hospitalized had higher antipsychotics chlorpromazine equivalent dosage, higher positive and negative syndrome scale total score, higher Udvalg for Kliniske Undersøgelser others mean score and were more likely to have an acute mode of onset compared with those who were not hospitalized.

CONCLUSIONS

Hospitalization was common in first-episode psychosis. Future studies are needed to explore possible programmes to prevent hospitalization in patients with first-episode psychosis.

Stevens-Johnson syndrome and toxic epidermal necrolysis in patients with malignancies

BACKGROUND

Malignancy is known to be associated with an increased mortality rate in patients with Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). However, risk factors contributing to the poor prognosis of patients with SJS/TEN with malignancies remain undefined.

OBJECTIVES

To explore the potential involvement of malignancy and its related factors contributing to the poor outcome of SJS/TEN, in a retrospective study.

METHODS

In total 517 patients with SJS/TEN were enrolled. Forty-seven who sustained various types of malignancies were analysed for numerous malignancy-related factors, including cancer types, clinical stages and chemotherapies given or not before the onset of SJS/TEN.

RESULTS

We found that the mortality rate of patients with SJS/TEN with malignancies was higher than that of patients without malignancies (32%, 15/47 vs. 8·5%, 40/470, respectively) (P < 0·001). The use of phenytoin was significantly higher in the malignancy group. The presence of hepatocellular carcinoma (80%, four of five; P < 0·001; odds ratio 43) and colorectal cancer (67%, two of three; P = 0·022; odds ratio 21·5) significantly increased the death rate of patients with SJS/TEN, whereas lung cancer and urothelial carcinoma did not. Patients who had received ongoing or recent chemotherapy showed higher mortality than those without chemotherapy (P = 0·022; odds ratio 4·95). Furthermore, among the 47 patients with SJS/TEN with malignancies, lower serum albumin, haemoglobin and platelet count were detected in the deceased patients than in the surviving patients before the onset of SJS/TEN.

CONCLUSIONS

Our results suggest that several factors related to malignancies, such as specific cancer types, chemotherapy and malnutrition, may contribute to poor prognosis in patients with malignancies developing SJS/TEN.

Measurements of Elliptic and Triangular Flow in High-Multiplicity 3He+Au Collisions at √(s(NN))=200 GeV

We present the first measurement of elliptic (v(2)) and triangular (v(3)) flow in high-multiplicity (3)He+Au collisions at √(s(NN))=200  GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in (3)He+Au and in p+p collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the (3)He+Au system. The collective behavior is quantified in terms of elliptic v(2) and triangular v(3) anisotropy coefficients measured with respect to their corresponding event planes. The v(2) values are comparable to those previously measured in d+Au collisions at the same nucleon-nucleon center-of-mass energy. Comparisons with various theoretical predictions are made, including to models where the hot spots created by the impact of the three (3)He nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.

Delusional disorder and schizophrenia: a comparison of the neurocognitive and clinical characteristics in first-episode patients

BACKGROUND

Delusional disorder (DD) is thought to be distinct from schizophrenia (SZ). However, few systematic investigations have been conducted on DD because of the difficulty in ascertaining a representative sample size. Existing knowledge has been mostly generated from inpatient cohorts, which may be biased towards a more severe sample.

METHOD

We compared the demographic, clinical and cognitive differences between 71 patients with first-episode DD and 71 age-matched patients with first-episode SZ. Participants were consecutively recruited from a population-based territory-wide study of early psychosis in Hong Kong targeting first-episode psychosis. Basic demographic information, premorbid functioning, duration of untreated psychosis, pathways to care, symptomatology, social, occupational, and cognitive functioning were comprehensively assessed using standardized measurements.

RESULTS

Patients with DD had less premorbid schizoid and schizotypal traits compared to patients with SZ. More patients with DD were married compared to patients with SZ. However, at first episode, there were no significant differences between the two groups in regards to the duration of untreated psychosis, pathways to care, symptom severity, neurocognitive performance, treatment, and functioning.

CONCLUSIONS

Our findings challenge previous thinking that patients with DD had better functioning than patients with SZ. This study not only provides an updated perspective into conceptualizing the clinical differences between DD and SZ, but also expands the descriptive account of the two disorders to include the neurocognitive dimension.

Rapid Reduction of the Diferric-Peroxyhemiacetal Intermediate in Aldehyde-Deformylating Oxygenase by a Cyanobacterial Ferredoxin: Evidence for a Free-Radical Mechanism

Aldehyde-deformylating oxygenase (ADO) is a ferritin-like nonheme-diiron enzyme that catalyzes the last step in a pathway through which fatty acids are converted into hydrocarbons in cyanobacteria. ADO catalyzes conversion of a fatty aldehyde to the corresponding alk(a/e)ne and formate, consuming four electrons and one molecule of O2 per turnover and incorporating one atom from O2 into the formate coproduct. The source of the reducing equivalents in vivo has not been definitively established, but a cyanobacterial [2Fe-2S] ferredoxin (PetF), reduced by ferredoxin-NADP(+) reductase (FNR) using NADPH, has been implicated. We show that both the diferric form of Nostoc punctiforme ADO and its (putative) diferric-peroxyhemiacetal intermediate are reduced much more rapidly by Synechocystis sp. PCC6803 PetF than by the previously employed chemical reductant, 1-methoxy-5-methylphenazinium methyl sulfate. The yield of formate and alkane per reduced PetF approaches its theoretical upper limit when reduction of the intermediate is carried out in the presence of FNR. Reduction of the intermediate by either system leads to accumulation of a substrate-derived peroxyl radical as a result of off-pathway trapping of the C2-alkyl radical intermediate by excess O2, which consequently diminishes the yield of the hydrocarbon product. A sulfinyl radical located on residue Cys71 also accumulates with short-chain aldehydes. The detection of these radicals under turnover conditions provides the most direct evidence to date for a free-radical mechanism. Additionally, our results expose an inefficiency of the enzyme in processing its radical intermediate, presenting a target for optimization of bioprocesses exploiting this hydrocarbon-production pathway.

Experimental Correlation of Substrate Position with Reaction Outcome in the Aliphatic Halogenase, SyrB2

The iron(II)- and 2-(oxo)glutarate-dependent (Fe/2OG) oxygenases catalyze an array of challenging transformations, but how individual members of the enzyme family direct different outcomes is poorly understood. The Fe/2OG halogenase, SyrB2, chlorinates C4 of its native substrate, l-threonine appended to the carrier protein, SyrB1, but hydroxylates C5 of l-norvaline and, to a lesser extent, C4 of l-aminobutyric acid when SyrB1 presents these non-native amino acids. To test the hypothesis that positioning of the targeted carbon dictates the outcome, we defined the positions of these three substrates by measuring hyperfine couplings between substrate deuterium atoms and the stable, EPR-active iron-nitrosyl adduct, a surrogate for reaction intermediates. The Fe-(2)H distances and N-Fe-(2)H angles, which vary from 4.2 Å and 85° for threonine to 3.4 Å and 65° for norvaline, rationalize the trends in reactivity. This experimental correlation of position to outcome should aid in judging from structural data on other Fe/2OG enzymes whether they suppress hydroxylation or form hydroxylated intermediates on the pathways to other outcomes.

10-year outcome study of an early intervention program for psychosis compared with standard care service

BACKGROUND

Despite evidence on the short-term benefits of early intervention (EI) service for psychosis, long-term outcome studies are limited by inconsistent results. This study examined the 10-year outcomes of patients with first-episode psychosis who received 2-year territory-wide EI service compared to those who received standard care (SC) in Hong Kong using an historical control design.

METHOD

Consecutive patients who received the EI service between 1 July 2001 and 30 June 2002, and with diagnosis of schizophrenia-spectrum disorders, were identified and matched with patients who received SC first presented to the public psychiatric service from 1 July 2000 to 30 June 2001. In total, 148 matched pairs of patients were identified. Cross-sectional information on symptomatology and functioning was obtained through semi-structured interview; longitudinal information on hospitalization, functioning, suicide attempts, mortality and relapse over 10 years was obtained from clinical database. There were 70.3% (N = 104) of SC and 74.3% (N = 110) of EI patients interviewed.

RESULTS

Results suggested that EI patients had reduced suicide rate (χ2 (1) = 4.35, p = 0.037), fewer number [odds ratio (OR) 1.56, χ2 = 15.64, p < 0.0001] and shorter duration of hospitalization (OR 1.29, χ2 = 4.06, p = 0.04), longer employment periods (OR -0.28, χ2 = 14.64, p < 0.0001) and fewer suicide attempts (χ2 = 11.47, df = 1, p = 0.001) over 10 years. At 10 years, no difference was found in psychotic symptoms, symptomatic remission and functional recovery.

CONCLUSIONS

The short-term benefits of the EI service on number of hospitalizations and employment was sustained after service termination, but the differences narrowed down. This suggests the need to evaluate the optimal duration of the EI service.

Prodromal psychosis: a case series of ten symptomatic patients

This case series provides an account of 10 patients with prodromal psychosis in Hong Kong over the course of 12 months between 2012 and 2014. Patterns of symptoms and functioning levels were noted each month and overall presentation was classified into 4 categories. Four patients' conditions were classified as fluctuating, 3 patients as improved, 2 patients as no change, and 1 patient as transition into psychosis. The noted observations were compared to the current conceptualisation of prodromal psychosis according to the clinical staging model of McGorry and colleagues. This case series provides insights into the condition in an Asian population and provides background data to inform future clinical research and mental health services.