pHusion: A robust and versatile toolset for automated detection and analysis of exocytosis

Exocytosis is a fundamental process used by eukaryotes to regulate the composition of the plasma membrane and facilitate cell-cell communication. To investigate exocytosis in neuronal morphogenesis, previously we developed computational tools with a graphical user interface to enable the automatic detection and analysis of exocytic events from fluorescence timelapse images. Though these tools were useful, we found the code was brittle and not easily adapted to different experimental conditions. Here we developed and validated a robust and versatile toolkit, named pHusion, for the analysis of exocytosis written in ImageTank, a graphical programming language that combines image visualization and numerical methods. We tested this method using a variety of imaging modalities and pH-sensitive fluorophores, diverse cell types, and various exocytic markers to generate a flexible and intuitive package. We show that VAMP3-mediated exocytosis occurs 30-times more frequently in melanoma cells compared with primary oligodendrocytes, that VAMP2-mediated fusion events in mature rat hippocampal neurons are longer lasting than those in immature murine cortical neurons, and that exocytic events are clustered in space yet random in time in developing cortical neurons.

Complete genome sequence of Gluconobacter frateurii ML.ISBL3, an endophytic strain isolated from aerial roots of Syngonium podophyllum

The endophytic strain Gluconobacter frateurii ML.ISBL3 was isolated from aerial roots of Syngonium podophyllum in Hong Kong. Its complete genome, established through hybrid assembly, comprises a single chromosome of 3,309,710 bp (56.30% G+C).

Complete genome sequence of Klebsiella variicola subsp. variicola ML.9ba2, an endophytic strain isolated from aerial roots of Philodendron erubescens

The endophytic strain Klebsiella variicola subsp. variicola ML.9ba2 was isolated from aerial roots of Philodendron erubescens in Hong Kong. Its complete genome of 5,682,083 bp (57.29% G+C), comprising a single chromosome and an IncF plasmid, was established through hybrid assembly.

MIR137 polygenic risk for schizophrenia and ephrin-regulated pathway: Role in lateral ventricles and corpus callosum volume

Background/Objective. Enlarged lateral ventricle (LV) volume and decreased volume in the corpus callosum (CC) are hallmarks of schizophrenia (SZ). We previously showed an inverse correlation between LV and CC volumes in SZ, with global functioning decreasing with increased LV volume. This study investigates the relationship between LV volume, CC abnormalities, and the microRNA MIR137 and its regulated genes in SZ, because of MIR137's essential role in neurodevelopment. Methods. Participants were 1224 SZ probands and 1466 unaffected controls from the GENUS Consortium. Brain MRI scans, genotype, and clinical data were harmonized across cohorts and employed in the analyses. Results. Increased LV volumes and decreased CC central, mid-anterior, and mid-posterior volumes were observed in SZ probands. The MIR137-regulated ephrin pathway was significantly associated with CC:LV ratio, explaining a significant proportion (3.42 %) of CC:LV variance, and more than for LV and CC separately. Other pathways explained variance in either CC or LV, but not both. CC:LV ratio was also positively correlated with Global Assessment of Functioning, supporting previous subsample findings. SNP-based heritability estimates were higher for CC central:LV ratio (0.79) compared to CC or LV separately. Discussion. Our results indicate that the CC:LV ratio is highly heritable, influenced in part by variation in the MIR137-regulated ephrin pathway. Findings suggest that the CC:LV ratio may be a risk indicator in SZ that correlates with global functioning.

SRF transcriptionally regulates the oligodendrocyte cytoskeleton during CNS myelination

Myelination of neuronal axons is essential for nervous system development. Myelination requires dramatic cytoskeletal dynamics in oligodendrocytes, but how actin is regulated during myelination is poorly understood. We recently identified serum response factor (SRF)-a transcription factor known to regulate expression of actin and actin regulators in other cell types-as a critical driver of myelination in the aged brain. Yet, a major gap remains in understanding the mechanistic role of SRF in oligodendrocyte lineage cells. Here, we show that SRF is required cell autonomously in oligodendrocytes for myelination during development. Combining ChIP-seq with RNA-seq identifies SRF-target genes in oligodendrocyte precursor cells and oligodendrocytes that include actin and other key cytoskeletal genes. Accordingly, SRF knockout oligodendrocytes exhibit dramatically reduced actin filament levels early in differentiation, consistent with its role in actin-dependent myelin sheath initiation. Surprisingly, oligodendrocyte-restricted loss of SRF results in upregulation of gene signatures associated with aging and neurodegenerative diseases. Together, our findings identify SRF as a transcriptional regulator that controls the expression of cytoskeletal genes required in oligodendrocytes for myelination. This study identifies an essential pathway regulating oligodendrocyte biology with high relevance to brain development, aging, and disease.

Oligodendrocyte calcium signaling promotes actin-dependent myelin sheath extension

Myelin is essential for rapid nerve signaling and is increasingly found to play important roles in learning and in diverse diseases of the CNS. Morphological parameters of myelin such as sheath length are thought to precisely tune conduction velocity, but the mechanisms controlling sheath morphology are poorly understood. Local calcium signaling has been observed in nascent myelin sheaths and can be modulated by neuronal activity. However, the role of calcium signaling in sheath formation remains incompletely understood. Here, we use genetic tools to attenuate oligodendrocyte calcium signaling during myelination in the developing mouse CNS. Surprisingly, genetic calcium attenuation does not grossly affect the number of myelinated axons or myelin thickness. Instead, calcium attenuation causes myelination defects resulting in shorter, dysmorphic sheaths. Mechanistically, calcium attenuation reduces actin filaments in oligodendrocytes, and an intact actin cytoskeleton is necessary and sufficient to achieve accurate myelin morphology. Together, our work reveals a cellular mechanism required for accurate CNS myelin formation and may provide mechanistic insight into how oligodendrocytes respond to neuronal activity to sculpt and refine myelin sheaths.

pHusion: A robust and versatile toolset for automated detection and analysis of exocytosis

Exocytosis is a fundamental process used by eukaryotic cells to regulate the composition of the plasma membrane and facilitate cell-cell communication. To investigate the role exocytosis plays in neuronal morphogenesis, previously we developed computational tools with a graphical user interface (GUI) to enable the automatic detection and analysis of exocytic events (ADAE GUI) from fluorescence timelapse images. Though these tools have proven useful, we found that the code was brittle and not easily adapted to different experimental conditions. Here, we have developed and validated a robust and versatile toolkit, named pHusion, for the analysis of exocytosis written in ImageTank, a graphical programming language that combines image visualization and numerical methods. We tested this method using a variety of imaging modalities and pH-sensitive fluorophores, diverse cell types, and various exocytic markers to generate a flexible and intuitive package. Using pHusion, we show that VAMP3-mediated exocytosis occurs 30-times more frequently in melanoma cells compared with primary oligodendrocytes, that VAMP2-mediated fusion events in mature rat hippocampal neurons are longer lasting than those in immature murine cortical neurons, and that exocytic events are clustered in space yet random in time in developing cortical neurons.

Summary Statement

Exocytosis is an essential process by which cells change shape, alter membrane composition, and communicate with other cells. Though all eukaryotic cells carry out exocytosis, the regulation of vesicle fusion, the cargo of vesicles, and the role exocytosis plays in cell fate differ greatly across cell types. Here, we developed a flexible and robust set of tools to enable automatic identification and analysis of exocytic events across a wide range of cell types, vesicle types, and imaging conditions.

BMAL1 loss in oligodendroglia contributes to abnormal myelination and sleep

Myelination depends on the maintenance of oligodendrocytes that arise from oligodendrocyte precursor cells (OPCs). We show that OPC-specific proliferation, morphology, and BMAL1 are time-of-day dependent. Knockout of Bmal1 in mouse OPCs during development disrupts the expression of genes associated with circadian rhythms, proliferation, density, morphology, and migration, leading to changes in OPC dynamics in a spatiotemporal manner. Furthermore, these deficits translate into thinner myelin, dysregulated cognitive and motor functions, and sleep fragmentation. OPC-specific Bmal1 loss in adulthood does not alter OPC density at baseline but impairs the remyelination of a demyelinated lesion driven by changes in OPC morphology and migration. Lastly, we show that sleep fragmentation is associated with increased prevalence of the demyelinating disorder multiple sclerosis (MS), suggesting a link between MS and sleep that requires further investigation. These findings have broad mechanistic and therapeutic implications for brain disorders that include both myelin and sleep phenotypes.

A Single-Institution Experience of Acute Neuropathic Lumbosacral Pain in Patients Treated with Short Course Hypofractionated Radiotherapy in Locally Advanced Rectal Cancer

PURPOSE/OBJECTIVE(S)

There has been increased interest in the use of short course hypofractionated radiotherapy as part of a total neoadjuvant treatment (TNT) approach in the management of rectal cancer since publication of the RAPIDO trial. However, the literature on short course radiation for rectal cancer has not reported significant acute toxicities in the weeks immediately following the completion of treatment. Anecdotally, a subset of patients has experienced acute neuropathic pain characterized in a lumbosacral distribution. This study investigates acute lumbosacral toxicity for patients receiving hypofractionated short course radiation as part of their definitive treatment for rectal cancer.

MATERIALS/METHODS

We retrospectively analyzed 75 patients with locally advanced rectal adenocarcinoma treated with hypofractionated short course radiation (25 Gy in 5 fractions) at our institution between 2016 and 2022. Acute toxicity caused by radiation was defined as that occurring from the start of radiation treatment to either 30 days post radiation completion, the start of chemotherapy, or date of surgery, whichever occurred first.

RESULTS

Among 75 patients treated with hypofractionated short course preoperative radiation with definitive intent, we identified 10 patients (13.3%) who experienced significant lumbosacral neuropathic pain and initiated a report to their medical providers during the acute toxicity time frame. Commonly, this was described as an achy pain in the bilateral buttocks radiating down to the knees or posterior claves. Patients rated this pain between moderate to extreme and management included steroids after failure of improvement with conservative measures, gabapentin, and conservative treatment with NSAIDs and Tylenol. Average time to onset of acute lumbosacral neuropathic pain was 3.7 days (SD 2.05) from start of RT.

CONCLUSION

We have identified a previously underappreciated acute toxicity of neuropathic lumbosacral pain in short course hypofractionated radiation therapy, which may be due to a lumbosacral plexus toxicity. Further analysis will seek to identify predictive factors such as comorbidities and dose to the lumbosacral plexus, and to determine whether there is a correlation between these observed acute toxicities and long-term outcomes.

Effect of Community Treatment Orders on Mental Health Service Usage, Emergency Visits, and Violence: a Systematic Review and Meta-Analysis

INTRODUCTION

Community treatment orders (CTOs) enable patients to actively engage in mental health services while being supervised in the community outside the hospital setting. However, the efficacy of CTOs remains controversial in terms of mental health services usage or service contacts, emergency visits, and violence.

METHODS

The databases PsychINFO, Embase, and Medline were searched on 11 March 2022 by 2 independent reviewers through the Covidence website (www.covidence.org). Randomised or non-randomised case-control studies and pre-post studies were included if they examine the effect of CTOs on service contacts, emergency visits, and violence in individuals with mental illnesses by comparing with control groups or pre-CTO conditions. Conflicts were resolved by consultation of the third independent reviewer.

RESULTS

Sixteen studies provided sufficient data in the target outcome measures and were included in analysis. Variability in the risk of bias was high among studies. Meta-analyses were conducted separately for case-control studies and pre-post studies. For service contacts, a total of 11 studies with 66,192 patients reported changes in the number of service contacts under CTOs. In 6 case-control studies, a small non-significant increase in service contacts was observed in those under CTOs (Hedge's g = 0.241, z = 1.535, p = 0.13). In 5 pre-post studies, a large and significant increase in service contacts was noted after CTOs (Hedge's g = 0.830, z = 5.056, p < 0.001). For emergency visits, a total of 6 studies with 930 patients reported changes in the number of emergency visits under CTOs. In 2 case-control studies, a small non-significant increase in emergency visits was noted in those under CTOs (Hedge's g = -0.196, z = -1.567, p = 0.117). In 4 pre-post studies, a small significant decrease in emergency visits was noted after CTOs (Hedge's g = 0.553, z = 3.101, p = 0.002). For violence, a total of 2 pre-post studies reported a moderate significant reduction in violence after CTOs (Hedge's g = 0.482, z = 5.173, p < 0.001).

CONCLUSION

Case-control studies showed inconclusive evidence, but pre-post studies showed significant effects of CTOs in promoting service contacts and reducing emergency visits and violence. Future studies on cost-effectiveness analysis and qualitative analysis for specific populations with various cultures and backgrounds are warranted.

Oligodendrocyte calcium signaling sculpts myelin sheath morphology

Myelin is essential for rapid nerve signaling and is increasingly found to play important roles in learning and in diverse diseases of the CNS. Morphological parameters of myelin such as sheath length and thickness are regulated by neuronal activity and can precisely tune conduction velocity, but the mechanisms controlling sheath morphology are poorly understood. Local calcium signaling has been observed in nascent myelin sheaths and can be modulated by neuronal activity. However, the role of calcium signaling in sheath formation and remodeling is unknown. Here, we used genetic tools to attenuate oligodendrocyte calcium signaling during active myelination in the developing mouse CNS. Surprisingly, we found that genetic calcium attenuation did not grossly affect the number of myelinated axons or myelin thickness. Instead, calcium attenuation caused striking myelination defects resulting in shorter, dysmorphic sheaths. Mechanistically, calcium attenuation reduced actin filaments in oligodendrocytes, and an intact actin cytoskeleton was necessary and sufficient to achieve accurate myelin morphology. Together, our work reveals a novel cellular mechanism required for accurate CNS myelin formation and provides mechanistic insight into how oligodendrocytes may respond to neuronal activity to sculpt myelin sheaths throughout the nervous system.

CNS myelination requires VAMP2/3-mediated membrane expansion in oligodendrocytes

Myelin is required for rapid nerve signaling and is emerging as a key driver of CNS plasticity and disease. How myelin is built and remodeled remains a fundamental question of neurobiology. Central to myelination is the ability of oligodendrocytes to add vast amounts of new cell membrane, expanding their surface areas by many thousand-fold. However, how oligodendrocytes add new membrane to build or remodel myelin is not fully understood. Here, we show that CNS myelin membrane addition requires exocytosis mediated by the vesicular SNARE proteins VAMP2/3. Genetic inactivation of VAMP2/3 in myelinating oligodendrocytes caused severe hypomyelination and premature death without overt loss of oligodendrocytes. Through live imaging, we discovered that VAMP2/3-mediated exocytosis drives membrane expansion within myelin sheaths to initiate wrapping and power sheath elongation. In conjunction with membrane expansion, mass spectrometry of oligodendrocyte surface proteins revealed that VAMP2/3 incorporates axon-myelin adhesion proteins that are collectively required to form nodes of Ranvier. Together, our results demonstrate that VAMP2/3-mediated membrane expansion in oligodendrocytes is indispensable for myelin formation, uncovering a cellular pathway that could sculpt myelination patterns in response to activity-dependent signals or be therapeutically targeted to promote regeneration in disease.

EANM procedure guideline for the treatment of liver cancer and liver metastases with intra-arterial radioactive compounds

Primary liver tumours (i.e. hepatocellular carcinoma (HCC) or intrahepatic cholangiocarcinoma (ICC)) are among the most frequent cancers worldwide. However, only 10-20% of patients are amenable to curative treatment, such as resection or transplant. Liver metastases are most frequently caused by colorectal cancer, which accounts for the second most cancer-related deaths in Europe. In both primary and secondary tumours, radioembolization has been shown to be a safe and effective treatment option. The vast potential of personalized dosimetry has also been shown, resulting in markedly increased response rates and overall survival. In a rapidly evolving therapeutic landscape, the role of radioembolization will be subject to changes. Therefore, the decision for radioembolization should be taken by a multidisciplinary tumour board in accordance with the current clinical guidelines. The purpose of this procedure guideline is to assist the nuclear medicine physician in treating and managing patients undergoing radioembolization treatment. PREAMBLE: The European Association of Nuclear Medicine (EANM) is a professional non-profit medical association that facilitates communication worldwide among individuals pursuing clinical and research excellence in nuclear medicine. The EANM was founded in 1985. These guidelines are intended to assist practitioners in providing appropriate nuclear medicine care for patients. They are not inflexible rules or requirements of practice and are not intended, nor should they be used, to establish a legal standard of care. The ultimate judgment regarding the propriety of any specific procedure or course of action must be made by medical professionals taking into account the unique circumstances of each case. Thus, there is no implication that an approach differing from the guidelines, standing alone, is below the standard of care. To the contrary, a conscientious practitioner may responsibly adopt a course of action different from that set out in the guidelines when, in the reasonable judgment of the practitioner, such course of action is indicated by the condition of the patient, limitations of available resources or advances in knowledge or technology subsequent to publication of the guidelines. The practice of medicine involves not only the science but also the art of dealing with the prevention, diagnosis, alleviation and treatment of disease. The variety and complexity of human conditions make it impossible to always reach the most appropriate diagnosis or to predict with certainty a particular response to treatment. Therefore, it should be recognised that adherence to these guidelines will not ensure an accurate diagnosis or a successful outcome. All that should be expected is that the practitioner will follow a reasonable course of action based on current knowledge, available resources and the needs of the patient to deliver effective and safe medical care. The sole purpose of these guidelines is to assist practitioners in achieving this objective.

Characterization of plasmatic proteins adsorption on poly(styrene sodium sulfonate) functionalized silicone surfaces

Proteins adsorption occurs spontaneously on biomaterial upon insertion within the body. The resulting protein layer influences biomaterial biocompatibility through enhanced bio-integration or, on the contrary, adverse reactions. Furthermore, upon adsorption, proteins can undergo modifications of their structure and, ultimately, their physicochemical properties and activity. Hence, the understanding of protein adsorption on implanted materials appears essential, as exemplified by silicone breast prostheses that might lead to serious health issues. Surface modifications with a bioactive polymer, poly(styrene sodium sulfonate)-polyNaSS, on a hydrophobic silicone surface that composes breast implants, have been successfully performed under UV irradiation by a radical surface polymerization. This strategy enhances cell biocompatibility and antibacterial features. Although detailed insights related to the mechanism are still scarce, polyNaSS is supposed to promote changes in the conformation and/or orientation of adsorbed plasma proteins, reducing the odd for a biofilm to form. The present work addresses more in-depth structural investigations of the adsorbed state of two plasma proteins: Bovine Serum Albumin (BSA), as a model protein, and fibronectin (FN), for its role in cell adhesion. Using Atomic force microscopy (AFM), we report that polyNaSS showed no significant impact on the BSA structure conversely to the FN one. However, imaging findings with AFM clearly outlined a change in the structural organization of FN, going from a nano fibrillar assembly with an average length of 130 nm to a globular one when the surface was grafted. Thus, it is highlighted that polyNaSS interacts specifically with FN. In addition, cell spreading assay of L929 fibroblasts on FN-coated surfaces with optical microscopy indicated no significant impact of the change in FN structure upon fibroblasts adhesion, which displayed active elongated shapes. The present features are crucial for understanding the cell adhesion mechanism induced by surface modification.

Therapeutic Options for the Treatment of Darier's Disease: A Comprehensive Review of the Literature

Darier's disease (also known as keratosis follicularis or dyskeratosis follicularis) is an autosomal dominant inherited disorder which manifests as hyperkeratotic greasy papules in the first or second decade of life. Aside from symptom management and behavioral modifications to avoid triggers, there are currently no validated treatments for Darier's disease (DD). However, a variety of treatments have been proposed in the literature including retinoids, steroids, vitamin D analogs, photodynamic therapy, and surgical excision. The purpose of this review article is to identify therapeutic options for treating DD and to outline the evidence underlying these interventions. A search was conducted in Medline for English language articles from inception to July 4, 2020. Our search identified a total of 474 nonduplicate studies, which were screened by title and abstract. Of these, 155 full text articles were screened against inclusion/exclusion criteria, and 113 studies were included in our review. We identified Grade B evidence for the following treatments of DD: oral acitretin, oral isotretinoin, systemic Vitamin A, topical tretinoin, topical isotretinoin, topical adapalene gel, topical 5-flououracil, topical calciptriol and tacalcitol (with sunscreen), grenz ray radiation, and x-ray radiation. All other evidence for treatments of DD consisted of case reports or case series, which is considered grade C evidence. Considering the quality and quantity of evidence, clinicians may consider initiating a trial of select topical or oral retinoids first in patients with localized or generalized DD, respectively.

106 Stentolith As an Uncommon Complication of Loss to Follow Up After Endoscopic Biliary Stenting

Introduction

Endoscopic biliary stenting is a common procedure, with indications from malignant obstruction to benign stone disease. We discuss a patient who re-presented after endoscopic stenting having been lost to follow up, with a large ‘stentolith’ requiring open CBD exploration.

Case Presentation

A 56-year-old female presented in 2013 with obstructive jaundice and a 2-week history of abdominal pain. She was a smoker, but otherwise had no past medical, surgical, or relevant family history. After initial workup, ERCP with sphincterotomy and pigtail stent placement was performed with interval laparoscopic cholecystectomy in 2014. Post-operative follow up was not arranged, and the patient subsequently re-presented in 2020 with fatigue. MRCP confirmed a proximal CBD stone and linear artefact. Open exploration facilitated removal of the stone-stent complex.

Discussion

Complications of stenting include cholangitis, stent occlusion and migration [2]. Stenting for failed biliary stone extraction is considered a temporary measure, with removal or exchange at three months (1). However, patients may be lost to follow up and return with non-specific symptoms. A rare cause is de novo formation of a gallstone calculus encasing the stent, a phenomenon termed “stentolith” [4]. Proposed pathophysiology is through promotion of bacterial proliferation by the stent, with biofilm formation and calcium bilirubinate precipitation [6]. Variation in formation has been described, with plastic stents developing circumferential stones [12-25], due to potential space between the wall and stent.

Conclusions

This highlights the importance of robust inter-disciplinary working; careful patient follows up and implementation of a mandatory registry at all hospitals for stented patients.

A retrospective study on risk assessment and management of forensic psychiatric inpatients in Hong Kong

The Department of Forensic Psychiatry of Castle Peak Hospital is the only facility in Hong Kong that provides territory-wide forensic psychiatric services for patients with criminal involvement. This retrospective study aimed to explore whether the rehabilitation programs provided by the department could significantly reduce the risks of forensic psychiatric inpatients as measured by the Short-Term Assessment of Risk and Treatability (START). START ratings of inpatients who were hospitalized in the department for more than 3 months and were discharged to the community during the period from 11 April 2015 to 31 March 2019 were analyzed. A total of 79 patients were assessed, of whom 61 (77.2%) were males. Fifty-four (68.4%) patients suffered from schizophrenia. START scores upon admission (strength score = 5.67; vulnerability score = 17.43) and upon discharge (strength score = 6.87, vulnerability score = 11.18) indicated significant reduction of risks among inpatients (p < 0.05).

Misfolded proteins bind and activate death receptor 5 to trigger apoptosis during unresolved endoplasmic reticulum stress

Disruption of protein folding in the endoplasmic reticulum (ER) activates the unfolded protein response (UPR)—a signaling network that ultimately determines cell fate. Initially, UPR signaling aims at cytoprotection and restoration of ER homeostasis; that failing, it drives apoptotic cell death. ER stress initiates apoptosis through intracellular activation of death receptor 5 (DR5) independent of its canonical extracellular ligand Apo2L/TRAIL; however, the mechanism underlying DR5 activation is unknown. In cultured human cells, we find that misfolded proteins can directly engage with DR5 in the ER-Golgi intermediate compartment, where DR5 assembles pro-apoptotic caspase 8-activating complexes. Moreover, peptides used as a proxy for exposed misfolded protein chains selectively bind to the purified DR5 ectodomain and induce its oligomerization. These findings indicate that misfolded proteins can act as ligands to activate DR5 intracellularly and promote apoptosis. We propose that cells can use DR5 as a late protein-folding checkpoint before committing to a terminal apoptotic fate.

Proteins are chains of building blocks called amino acids, folded into a flexible 3D shape that is critical for its biological activity. This shape depends on many factors, but one is the chemistry of the amino acids. Because the internal and external environments of cells are mostly water-filled, correctly folded proteins often display so-called hydrophilic (or ‘water-loving’) amino acids on their surface, while tucking hydrophobic (or ‘water-hating’) amino acids on the inside.

A compartment within the cell called the endoplasmic reticulum folds the proteins that are destined for the outside of the cell. It can handle a steady stream of protein chains, but a sudden increase in demand for production, or issues with the underlying machinery, can stress the endoplasmic reticulum and hinder protein folding. This is problematic because incorrectly folded proteins cannot work as they should and can be toxic to the cell that made them or even to other cells. Many cells handle this kind of stress by activating a failsafe alarm system called the unfolded protein response. It detects the presence of incorrectly shaped proteins and sends signals that try to protect the cell and restore protein folding to normal. If that fails within a certain period of time, it switches to signals that tell the cell to safely self-destruct. That switch, from protection to self-destruction, involves a protein called death receptor 5, or DR5 for short. DR5 typically triggers the cell’s self-destruct program by forming molecular clusters at the cell’s surface, in response to a signal it receives from the exterior. During a failed unfolded protein response, DR5 seems instead to act in response to signals from inside the cell, but it was not clear how this works.

To find out, Lam et al. stressed the endoplasmic reticulum in human cells by forcing it to fold a lot of proteins. This revealed that DR5 sticks to misfolded proteins when they leave the endoplasmic reticulum. In response, DR5 molecules form clusters that trigger the cell's self-destruct program. DR5 directly recognized hydrophobic amino acids on the misfolded protein’s surface that would normally be hidden inside. When Lam et al. edited these hydrophobic regions to become hydrophilic, the DR5 molecules could no longer detect them as well. This stopped the cells from dying so easily when they were under stress. It seems that DR5 decides the fate of the cell by detecting proteins that were incorrectly folded in the endoplasmic reticulum.

Problems with protein folding occur in many human diseases, including metabolic conditions, cancer and degenerative brain disorders. Future work could reveal whether controlling the activation of DR5 could help to influence if and when cells die. The next step is to understand how DR5 interacts with incorrectly folded proteins at the atomic level. This could aid the design of drugs that specifically target such receptors.

1050 Normal imaging findings after aortic valve implantation on 18f-fluorodeoxyglucose positron emission tomography with computed tomography and computed tomography angiography

Purpose

Although 18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET) with computed tomography (CT) and cardiac computed tomography angiography (CTA) are essential tools in diagnosing prosthetic heart valve (PHV) endocarditis, the normal imaging findings in the first year after PHV implantation on 18F-FDG-PET/CT and CTA have not been studied prospectively. We prospectively assessed the perivalvular FDG uptake at different time points after aortic PHV implantation and assessed the normal imaging findings on CTA.

Materials and methods

Patients who had undergone uncomplicated aortic PHV implantation were included and underwent 18F-FDG PET/CT and CTA at 5(±1) weeks (group 1), 12(±2) weeks (group 2) or 52(±8) weeks (group 3) after implantation. After a preparatory diet to suppress normal myocardial glucose uptake, FDG uptake in the myocardium as well as around the PHV was scored using the Qualification Visual Score for Hypermetabolism (QVSH) as "none" (&lt; mediastinum), "low" (&gt; mediastinum but &lt; liver), "intermediate" (&gt; liver), or "high" (intense uptake) and quantitative analysis was performed with maximum Standardized Uptake Value (SUVmax) and target to background ratio (SUVratio) on standardized European Association of Nuclear Medicine Research Ltd. (EARL) reconstructions by an experienced nuclear medicine physician. CTA was analysed for image quality, artefacts and stranding of the peri-aortic fat by a cardiac radiologist.

Results

In total 37 patients (group 1: n = 12, group 2: n = 12, group 3: n = 13) (age 66 ± 8 years) were included. Myocardial FDG uptake was intermediate or less in 29/37 scans (78%). QVSH around the PHV was 8/12(67%) low and 4/12(33%) intermediate in group 1, 7/12(58%) low and 5/12(42%) intermediate in group 2 and 8/13(62%) low and 5/13(38%) intermediate in group 3 (p = 0.91). No scan was scored as "none" or "high". EARL SUVmax was 3.48 ± 0.57, 3.50 ± 0.59 and 3.34 ± 0.55 (mean ± SD, p = 0.77) and EARL SUVratio was 2.00 ± 0.29, 1.96 ± 0.41 and 1.71 ± 0.26 (mean ± SD, p = 0.07) for groups 1, 2 and 3, respectively.

One patient in group 3 refused to undergo the additional CTA and one CTA in group 3 could not be analysed for image quality and artefacts due to techniqual difficulties. Overall CTA image quality was "good" or "excellent" with an artefact score of "virtually none" or "mild" in most cases (n = 33, 94%). Stranding of peri-aortic fat was seen in 27/35 (77%) of these patients (group 1: n = 11; group 2: n = 9; group 3: n = 7) with no signs of FDG uptake on PET/CT scan.

Conclusion

Baseline FDG uptake around aortic PHV at 5, 12 and 52 weeks after implantation is similar and mild in the majority of cases with an overall mean SUVmax and SUVratio of 3.44 ± 0.56 and 1.89 ± 0.34 respectively. CTA revealed baseline post-surgical findings in the first year after PHV implantation.

The Mars1 kinase confers photoprotection through signaling in the chloroplast unfolded protein response

In response to proteotoxic stress, chloroplasts communicate with the nuclear gene expression system through a chloroplast unfolded protein response (cpUPR). We isolated Chlamydomonas reinhardtii mutants that disrupt cpUPR signaling and identified a gene encoding a previously uncharacterized cytoplasmic protein kinase, termed Mars1-for mutant affected in chloroplast-to-nucleus retrograde signaling-as the first known component in cpUPR signal transmission. Lack of cpUPR induction in MARS1 mutant cells impaired their ability to cope with chloroplast stress, including exposure to excessive light. Conversely, transgenic activation of cpUPR signaling conferred an advantage to cells undergoing photooxidative stress. Our results indicate that the cpUPR mitigates chloroplast photodamage and that manipulation of this pathway is a potential avenue for engineering photosynthetic organisms with increased tolerance to chloroplast stress.

Theoretical assessment of the impact of desert aerosols on the dynamical transmission of meningitidis serogroup A

This paper has been motivated by the following biological question: how influential are desert aerosols in the transmission of meningitidis serogroup A (MenA)? A mathematical model for the dynamical transmission of MenA is considered, with the aim of investigating the impact of desert aerosols. Sensitivity analysis of the model has been performed in order to determine the impact of related parameters on meningitis outbreak. We derive the basic reproduction number [Formula: see text]. We prove that there exists a threshold parameter [Formula: see text] such that when [Formula: see text], the disease-free equilibrium is globally asymptotically stable (GAS). However, when [Formula: see text], the model exhibits the phenomenon of backward bifurcation. At the endemic level, we show that the number of infectious individuals in the presence of desert aerosols is larger than the corresponding number without the presence of desert aerosols. In conjunction with the inequality [Formula: see text] where [Formula: see text] is the basic reproduction number without desert aerosols, we found that the ingestion of aerosols by carriers will increase the endemic level, and the severity of the outbreak. This suggests that the control of MenA passes through a combination of a large coverage vaccination of young susceptible individuals and the production of a vaccine with a high level of efficacy as well as respecting the hygienic rules to avoid the inhalation of desert aerosols. Theoretical results are supported by numerical simulations.

Theoretical assessment of the impact of environmental contamination on the dynamical transmission of polio

A mathematical model for the dynamical transmission of polio is considered, with the aim of investigating the impact of environment contamination. The model captures two infection pathways through both direct human-to-human transmission and indirect human-to-environment-to-human transmission by incorporating the environment as a transition and/or reservoir of viruses. We derive the basic reproduction number [Formula: see text]. We show that the disease free equilibrium is globally asymptotically stable (GAS) if [Formula: see text], while if [Formula: see text], there exists a unique endemic equilibrium which is locally asymptotically stable (LAS). Similar results hold for environmental contamination free sub-model (without the incorporation of the indirect transmission). At the endemic level, we show that the number of infected individuals for the model with the environmental-related contagion is greater than the corresponding number for the environmental contamination free sub-model. In conjunction with the inequality [Formula: see text], where [Formula: see text] is the basic reproduction number for the environmental contamination free sub-model, our finding suggests that the contaminated environment plays a detrimental role on the transmission dynamics of polio disease by increasing the endemic level and the severity of the outbreak. Therefore, it is natural to implement control strategies to reduce the severity of the disease by providing adequate hygienic living conditions, educate populations at risk to follow rigorously those basic hygienic rules in order to avoid adequate contacts with suspected contaminated objects. Further, we perform numerical simulations to support the theory.

Profiling Mentally Ill Offenders in Hong Kong: a 5-year Retrospective Review Study

OBJECTIVES

This study aimed to determine the prevalence of mental illness in offenders referred to psychiatrists from January 2011 to March 2016 and any associations between crime and mental illness in these offenders.

METHODS

Case notes of offenders referred to psychiatrists at the Siu Lam Psychiatric Centre from 1 January 2011 to 31 March 2016 were reviewed. Data on sex, age on admission, educational level, principal psychiatric diagnosis, index offence, source and reason of referral, and outcome were collected.

RESULTS

Case notes were reviewed for 4492 offenders (75% males) aged 14 to 93 (mean, 40.6) years. Of these, 68% were referred by the courts for psychiatric report and 32% were referred by correctional institutions for psychiatric assessment and treatment. Approximately 73% of them had a diagnosable mental disorder. The most common principal psychiatric diagnoses were schizophrenia and related disorders (25%), mental and behavioural disorders due to psychoactive substance use (20%), and mood disorders (9%). The most common index offences were theft and related offences (22%), acts intended to cause injury (20%), and illicit drug offences (11%). Offences involving violence were more prevalent in males than in females (p < 0.001). In terms of the three most common principal psychiatric diagnoses, 'acts intended to cause injury' was most prevalent in those with 'schizophrenia and other related disorders' than in those with the other two diagnoses (31% vs 19% vs 17%, p < 0.001). 'Theft and related offences' was most prevalent in those with mood disorders than in those with other two diagnoses (38% vs 20% vs 18%, p < 0.001). 'Illicit drug offences' was most prevalent in those with 'mental and behavioural disorders due to psychoactive substance' than those with other two diagnoses (22% vs 8% vs 6%, p < 0.001).

CONCLUSIONS

The prevalence of mental disorders among offenders referred to psychiatrists is high. The pattern of associations between crime and mental disorders in these offenders is comparable with that reported in overseas studies. As Siu Lam Psychiatric Centre is the only facility in Hong Kong for mentally ill offenders, our sample is representative, and our results provide cross-sectional pattern of forensic psychiatric service utilisation in Hong Kong.