Spider mite herbivory induces an abscisic acid-driven stomatal defense

Arthropod herbivory poses a serious threat to crop yield, prompting plants to employ intricate defense mechanisms against pest feeding. The generalist pest two-spotted spider mite (Tetranychus urticae) inflicts rapid damage and remains challenging due to its broad target range. In this study, we explored the Arabidopsis (Arabidopsis thaliana) response to T. urticae infestation, revealing the induction of abscisic acid (ABA), a hormone typically associated with abiotic stress adaptation, and stomatal closure during water stress. Leveraging a FRET-based ABA biosensor (nlsABACUS2-400n), we observed elevated ABA levels in various leaf cell types post-mite feeding. While ABA's role in pest resistance or susceptibility has been debated, an ABA-deficient mutant exhibited increased mite infestation alongside intact canonical biotic stress signaling, indicating an independent function of ABA in mite defense. We established that ABA-triggered stomatal closure effectively hinders mite feeding and minimizes leaf cell damage through genetic and pharmacological interventions targeting ABA levels, ABA signaling, stomatal aperture, and density. This study underscores the critical interplay between biotic and abiotic stresses in plants, highlighting how the vulnerability to mite infestation arising from open stomata, crucial for transpiration and photosynthesis, reinforces the intricate relationship between these stress types.

Next-generation ABACUS biosensors reveal cellular ABA dynamics driving root growth at low aerial humidity

The plant hormone abscisic acid (ABA) accumulates under abiotic stress to recast water relations and development. To overcome a lack of high-resolution sensitive reporters, we developed ABACUS2s-next-generation Förster resonance energy transfer (FRET) biosensors for ABA with high affinity, signal-to-noise ratio and orthogonality-that reveal endogenous ABA patterns in Arabidopsis thaliana. We mapped stress-induced ABA dynamics in high resolution to reveal the cellular basis for local and systemic ABA functions. At reduced foliar humidity, root cells accumulated ABA in the elongation zone, the site of phloem-transported ABA unloading. Phloem ABA and root ABA signalling were both essential to maintain root growth at low humidity. ABA coordinates a root response to foliar stresses, enabling plants to maintain foraging of deeper soil for water uptake.

ABA signaling prevents phosphodegradation of the SR45 splicing factor to alleviate inhibition of early seedling development in Arabidopsis

Serine/arginine-rich (SR) proteins are conserved splicing regulators that play important roles in plant stress responses, namely those mediated by the abscisic acid (ABA) hormone. The Arabidopsis thaliana SR-like protein SR45 is a described negative regulator of the ABA pathway during early seedling development. How the inhibition of growth by ABA signaling is counteracted to maintain plant development under stress conditions remains largely unknown. Here, we show that SR45 overexpression reduces Arabidopsis sensitivity to ABA during early seedling development. Biochemical and confocal microscopy analyses of transgenic plants expressing fluorescently tagged SR45 revealed that exposure to ABA dephosphorylates the protein at multiple amino acid residues and leads to its accumulation, due to SR45 stabilization via reduced ubiquitination and proteasomal degradation. Using phosphomutant and phosphomimetic transgenic Arabidopsis lines, we demonstrate the functional relevance of ABA-mediated dephosphorylation of a single SR45 residue, T264, in antagonizing SR45 ubiquitination and degradation to promote its function as a repressor of seedling ABA sensitivity. Our results reveal a mechanism that negatively autoregulates ABA signaling and allows early plant growth under stress via posttranslational control of the SR45 splicing factor.

Chemical bonds in collagen rupture selectively under tensile stress

Collagen fibres are the main constituent of the extracellular matrix, and fulfil an important role in the structural stability of living multicellular organisms. An open question is how collagen absorbs pulling forces, and if the applied forces are strong enough to break bonds, what mechanisms underlie this process. As experimental studies on this topic are challenging, simulations are an important tool to further our understanding of these mechanisms. Here, we present pulling simulations of collagen triple helices, revealing the molecular mechanisms induced by tensile stress. At lower forces, pulling alters the configuration of proline residues leading to an effective absorption of applied stress. When forces are strong enough to introduce bond ruptures, these are located preferentially in X-position residues. Reduced backbone flexibility, for example through mutations or cross linking, weakens tensile resistance, leading to localised ruptures around these perturbations. In fibre-like segments, a significant overrepresentation of ruptures in proline residues compared to amino acid contents is observed. This study confirms the important role of proline in the structural stability of collagen, and adds detailed insight into the molecular mechanisms underlying this observation.

Hydraulic flux-responsive hormone redistribution determines root branching

Plant roots exhibit plasticity in their branching patterns to forage efficiently for heterogeneously distributed resources, such as soil water. The xerobranching response represses lateral root formation when roots lose contact with water. Here, we show that xerobranching is regulated by radial movement of the phloem-derived hormone abscisic acid, which disrupts intercellular communication between inner and outer cell layers through plasmodesmata. Closure of these intercellular pores disrupts the inward movement of the hormone signal auxin, blocking lateral root branching. Once root tips regain contact with moisture, the abscisic acid response rapidly attenuates. Our study reveals how roots adapt their branching pattern to heterogeneous soil water conditions by linking changes in hydraulic flux with dynamic hormone redistribution.

The Winchcombe meteorite, a unique and pristine witness from the outer solar system

Direct links between carbonaceous chondrites and their parent bodies in the solar system are rare. The Winchcombe meteorite is the most accurately recorded carbonaceous chondrite fall. Its pre-atmospheric orbit and cosmic-ray exposure age confirm that it arrived on Earth shortly after ejection from a primitive asteroid. Recovered only hours after falling, the composition of the Winchcombe meteorite is largely unmodified by the terrestrial environment. It contains abundant hydrated silicates formed during fluid-rock reactions, and carbon- and nitrogen-bearing organic matter including soluble protein amino acids. The near-pristine hydrogen isotopic composition of the Winchcombe meteorite is comparable to the terrestrial hydrosphere, providing further evidence that volatile-rich carbonaceous asteroids played an important role in the origin of Earth's water.

Frequency and Longitudinal Course of Motor Signs in Genetic Frontotemporal Dementia

BACKGROUND AND OBJECTIVES

Frontotemporal dementia (FTD) is a highly heritable disorder. The majority of genetic cases are caused by autosomal dominant pathogenic variants in the chromosome 9 open reading frame 72 (c9orf72), progranulin (GRN), and microtubule-associated protein tau (MAPT) gene. As motor disorders are increasingly recognized as part of the clinical spectrum, the current study aimed to describe motor phenotypes caused by genetic FTD, quantify their temporal association, and investigate their regional association with brain atrophy.

METHODS

We analyzed baseline visit data of known carriers of a pathogenic variant in the c9orf72, GRN, or MAPT gene from the Genetic Frontotemporal Dementia Initiative cohort study. Principal component analysis with varimax rotation was performed to identify motor sign clusters that were compared with respect to frequency and severity between groups. Associations with cross-sectional atrophy patterns were determined using voxel-wise regression. We applied linear mixed effects models to assess whether groups differed in the association between motor signs and estimated time to symptom onset.

RESULTS

A total of 322 pathogenic variant carriers were included in the analysis: 122 c9orf72 (79 presymptomatic), 143 GRN (112 presymptomatic), and 57 MAPT (43 presymptomatic) pathogenic variant carriers. Principal component analysis revealed 5 motor clusters, which we call progressive supranuclear palsy (PSP)-like, bulbar amyotrophic lateral sclerosis (ALS)-like, mixed/ALS-like, Parkinson disease (PD) like, and corticobasal syndrome-like motor phenotypes. There was no significant group difference in the frequency of signs of different motor phenotypes. However, mixed/ALS-like motor signs were most frequent, followed by PD-like motor signs. Although the PSP-like phenotype was associated with mesencephalic atrophy, the mixed/ALS-like phenotype was associated with motor cortex and corticospinal tract atrophy. The PD-like phenotype was associated with widespread cortical and subcortical atrophy. Estimated time to onset, genetic group and their interaction influenced motor signs. In c9orf72 pathogenic variant carriers, motor signs could be detected up to 25 years before expected symptom onset.

DISCUSSION

These results indicate the presence of multiple natural clusters of motor signs in genetic FTD, each correlated with specific atrophy patterns. Their motor severity depends on time and the affected gene. These clinicogenetic associations can guide diagnostic evaluations and the design of clinical trials for new disease-modifying and preventive treatments.

Locus Coeruleus Integrity from 7 T MRI Relates to Apathy and Cognition in Parkinsonian Disorders

BACKGROUND

Neurodegeneration in the locus coeruleus (LC) contributes to neuropsychiatric symptoms in both Parkinson's disease (PD) and progressive supranuclear palsy (PSP). Spatial precision of LC imaging is improved with ultrahigh field 7 T magnetic resonance imaging.

OBJECTIVES

This study aimed to characterize the spatial patterns of LC pathological change in PD and PSP and the transdiagnostic relationship between LC signals and neuropsychiatric symptoms.

METHODS

Twenty-five people with idiopathic PD, 14 people with probable PSP-Richardson's syndrome, and 24 age-matched healthy controls were recruited. Participants underwent clinical assessments and high-resolution (0.08 mm3 ) 7 T-magnetization-transfer imaging to measure LC integrity in vivo. Spatial patterns of LC change were obtained using subregional mean contrast ratios and significant LC clusters; we further correlated the LC contrast with measures of apathy and cognition, using both mixed-effect models and voxelwise analyses.

RESULTS

PSP and PD groups showed significant LC degeneration in the caudal subregion relative to controls. Mixed-effect models revealed a significant interaction between disease-group and apathy-related correlations with LC degeneration (β = 0.46, SE [standard error] = 0.17, F(1, 35) = 7.46, P = 0.01), driven by a strong correlation in PSP (β = -0.58, SE = 0.21, t(35) = -2.76, P = 0.009). Across both disease groups, voxelwise analyses indicated that lower LC integrity was associated with worse cognition and higher apathy scores.

CONCLUSIONS

The relationship between LC and nonmotor symptoms highlights a role for noradrenergic dysfunction across both PD and PSP, confirming the potential for noradrenergic therapeutic strategies to address transdiagnostic cognitive and behavioral features in neurodegenerative disease. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Co-Occurrence of Apathy and Impulsivity in Progressive Supranuclear Palsy

Background

Apathy and impulsivity are common consequences of progressive supranuclear palsy (PSP) and can worsen its prognosis. They can co‐exist in the same patients although their concomitant prevalence remains unclear. Their relationship to emotional lability is unknown.

Objectives

To estimate the co‐occurrence of apathy and impulsivity and their relationship to emotional lability in PSP. To characterize the demographic, clinical, and cognitive features of PSP patients with apathy and impulsivity.

Methods

In a retrospective study of a long‐term clinical cohort, we assessed the prevalence of apathy, impulsivity, and emotional lability from clinical interviews, medical records, and contemporary carer questionnaires. One hundred fifty‐four patients with a diagnosis of probable or possible PSP (according to the 2017 Movement Disorder Society criteria) were identified. Sixty‐four of these patients had neuropathological confirmation of PSP. PSP patients with both apathy and impulsivity were compared in terms of demographic, clinical, and cognitive characteristics to PSP patients with either one or neither of these neuropsychiatric features.

Results

Apathy and impulsivity co‐existed in two‐thirds of people with PSP. A fifth displayed emotional lability in addition to apathy and impulsivity. Apathy and impulsivity were more commonly co‐expressed than by chance. There was no single demographic, clinical or cognitive feature that distinguished between PSP patients with versus patients without apathy and impulsivity.

Conclusions

The co‐existence of apathy and impulsivity in PSP suggests that these neuropsychiatric features may share similar risk factors and etio‐pathogenetic mechanisms. Apathy and impulsivity should be jointly assessed when planning symptomatic treatments for detrimental behavioral problems caused by PSP.

Prometastatic CXCR4 and Histone Methyltransferase EZH2 are Upregulated in SMARCB1/INI1-deficient and TP53-mutated Metastatic Poorly Differentiated Chordoma to the Liver

Introduction/Objective

Chordoma is a rare tumor most commonly arising in the sacrococcygeal region from notochord remnants. Usually, these tumors are locally invasive and recurrent, but do not have the capability to metastasize. A newly described aggressive variant called poorly differentiated chordoma is different than conventional chordoma in that it does not have the well-differentiated histologic appearance of conventional chordoma and also exhibits loss of SMARCB1/INI1.

Methods

Herein, we describe a case of poorly differentiated chordoma with SMARCB1/INI1 loss, concurrent TP53 mutation and Rb1 loss.

Results

The patient is a 55-year-old man with a history of a previously resected sacrococcygeal chordoma, who was found to have new hepatic, lung, and adrenal lesions. Biopsy of the liver showed sheets of malignant epithelioid cells with vacuolated cytoplasm, areas of necrosis, and up to 5 mitoses in one high power field. No physaliferous features or matrix material were seen. After an extensive panel of immunohistochemical markers, the origin of the metastatic tumor could not be determined and the tumor was only positive for Cam5.2, EMA, and CD56. Brachyury was performed due to the patient’s previous history and was positive. Genomic testing showed a SMARCB1 mutation, a TP53 mutation, and RB1 loss. Additional markers were performed and the tumor showed a Ki-67 proliferation index of approximately 80%, mutant p53 protein, loss of INI1, and strong expression of prometastatic CXCR4 and the histone methyltransferase EZH2. The most recent follow-up of the patient showed that the patient was receiving palliative care.

Conclusion

Poorly differentiated chordoma is a highly aggressive variant of chordoma with few cases reported. This case of SMARCB1/INI-deficient, poorly differentiated chordoma also showed concurrent TP53 mutation and loss of RB1, which resulted in malignant transformation with loss of differentiation, cell cycle progression, up-regulation of prometastatic CXCR4 and the histone methyltransferase EZH2 causing aggressive behavior and metastasis.

HY5 is not integral to light mediated stomatal development in Arabidopsis

Light is a crucial signal that regulates many aspects of plant physiology and growth including the development of stomata, the pores in the epidermal surface of the leaf. Light signals positively regulate stomatal development leading to changes in stomatal density and stomatal index (SI; the proportion of cells in the epidermis that are stomata). Both phytochrome and cryptochrome photoreceptors are required to regulate stomatal development in response to light. The transcription factor ELONGATED HYPOCOTYL 5 (HY5) is a key regulator of light signalling, acting downstream of photoreceptors. We hypothesised that HY5 could regulate stomatal development in response to light signals due to the putative presence of HY5 binding sites in the promoter of the STOMAGEN (STOM) gene, which encodes a peptide regulator of stomatal development. Our analysis shows that HY5 does have the potential to regulate the STOM promoter in vitro and that HY5 is expressed in both the epidermis and mesophyll. However, analysis of hy5 and hy5 hyh double mutants (HYH; HY5-HOMOLOG), found that they had normal stomatal development under different light conditions and the expression of stomatal developmental genes was not perturbed following light shift experiments. Analysis of stable lines overexpressing HY5 also showed no change in stomatal development or the expression of stomatal developmental genes. We therefore conclude that whilst HY5 has the potential to regulate the expression of STOM, it does not have a major role in regulating stomatal development in response to light signals.

Stability of Metronidazole Free-base Oral Suspensions Formulated with United States Pharmacopeia-grade Metronidazole Powder and Commercial Metronidazole Tablets

This study reports on the stability of United States Pharmacopeia-grade metronidazole powder and commercially available metronidazole tablets in two dye-free oral suspending vehicles, namely Oral Mix and Oral Mix Sugar-Free. Metronidazole at 50 mg/mL was prepared individually in Oral Mix and Oral Mix Sugar-Free suspension vehicles and placed in 50-mL amber polyethyleneterephthalate bottles and 3-mL amber plastic syringes and stored at 4°C or 25°C/60% relative humidity for 90 days. The solutions were analyzed at the time of preparation and at 7 days, 14 days, 30 days, 45 days, 60 days, 75 days, and 90 days, with the concentration of metronidazole measured by high-performance liquid chromatography with photodiode array detection. The oral solutions were also monitored for pH, homogeneity, color, and odor. Except for the Oral Mix suspension of metronidazole prepared from the United States Pharmacopeia-grade powder and from the commercial tablet, when stored in pre-filled syringes, all the other preparations were stable at 4°C or 25°C/60% relative humidity for 90 days, with the metronidazole remaining within ± 10% of the initial concentration. The pH, color, odor, and resuspendability remained essentially unchanged. Metronidazole in Oral Mix and Oral Mix Sugar-Free oral suspensions, compounded from United States Pharmacopeia-grade powder or commercially available tablets, are a suitable alternative as an extemporaneously prepared medication.

Ventricular volume expansion in presymptomatic genetic frontotemporal dementia

Objective

To characterize the time course of ventricular volume expansion in genetic frontotemporal dementia (FTD) and identify the onset time and rates of ventricular expansion in presymptomatic FTD mutation carriers.

Methods

Participants included patients with a mutation in MAPT, PGRN, or C9orf72, or first-degree relatives of mutation carriers from the GENFI study with MRI scans at study baseline and at 1 year follow-up. Ventricular volumes were obtained from MRI scans using FreeSurfer, with manual editing of segmentation and comparison to fully automated segmentation to establish reliability. Linear mixed models were used to identify differences in ventricular volume and in expansion rates as a function of time to expected disease onset between presymptomatic carriers and noncarriers.

Results

A total of 123 participants met the inclusion criteria and were included in the analysis (18 symptomatic carriers, 46 presymptomatic mutation carriers, and 56 noncarriers). Ventricular volume differences were observed 4 years prior to symptom disease onset for presymptomatic carriers compared to noncarriers. Annualized rates of ventricular volume expansion were greater in presymptomatic carriers relative to noncarriers. Importantly, time-intensive manually edited and fully automated ventricular volume resulted in similar findings.

Conclusions

Ventricular volume differences are detectable in presymptomatic genetic FTD. Concordance of results from time-intensive manual editing and fully automatic segmentation approaches support its value as a measure of disease onset and progression in future studies in both presymptomatic and symptomatic genetic FTD.

Tackling gaps in developing life-changing treatments for dementia

Since the G8 dementia summit in 2013, a number of initiatives have been established with the aim of facilitating the discovery of a disease-modifying treatment for dementia by 2025. This report is a summary of the findings and recommendations of a meeting titled "Tackling gaps in developing life-changing treatments for dementia", hosted by Alzheimer's Research UK in May 2018. The aim of the meeting was to identify, review, and highlight the areas in dementia research that are not currently being addressed by existing initiatives. It reflects the views of leading experts in the field of neurodegeneration research challenged with developing a strategic action plan to address these gaps and make recommendations on how to achieve the G8 dementia summit goals. The plan calls for significant advances in (1) translating newly identified genetic risk factors into a better understanding of the impacted biological processes; (2) enhanced understanding of selective neuronal resilience to inform novel drug targets; (3) facilitating robust and reproducible drug-target validation; (4) appropriate and evidence-based selection of appropriate subjects for proof-of-concept clinical trials; (5) improving approaches to assess drug-target engagement in humans; and (6) innovative approaches in conducting clinical trials if we are able to detect disease 10-15 years earlier than we currently do today.

The inner fluctuations of the brain in presymptomatic Frontotemporal Dementia: The chronnectome fingerprint

Frontotemporal Dementia (FTD) is preceded by a long period of subtle brain changes, occurring in the absence of overt cognitive symptoms, that need to be still fully characterized. Dynamic network analysis based on resting-state magnetic resonance imaging (rs-fMRI) is a potentially powerful tool for the study of preclinical FTD. In the present study, we employed a "chronnectome" approach (recurring, time-varying patterns of connectivity) to evaluate measures of dynamic connectivity in 472 at-risk FTD subjects from the Genetic Frontotemporal dementia research Initiative (GENFI) cohort. We considered 249 subjects with FTD-related pathogenetic mutations and 223 mutation non-carriers (HC). Dynamic connectivity was evaluated using independent component analysis and sliding-time window correlation to rs-fMRI data, and meta-state measures of global brain flexibility were extracted. Results show that presymptomatic FTD exhibits diminished dynamic fluidity, visiting less meta-states, shifting less often across them, and travelling through a narrowed meta-state distance, as compared to HC. Dynamic connectivity changes characterize preclinical FTD, arguing for the desynchronization of the inner fluctuations of the brain. These changes antedate clinical symptoms, and might represent an early signature of FTD to be used as a biomarker in clinical trials.

Neuroticism predicts the impact of serotonin challenges on fear processing in subgenual anterior cingulate cortex

The personality trait neuroticism is associated with increased vulnerability to anxiety and mood disorders, conditions linked with abnormal serotonin neurotransmission and emotional processing. The interaction between neuroticism and serotonin during emotional processing is however not understood. Here we investigate how individual neuroticism scores influence the neural response to negative emotional faces and their sensitivity to serotonergic tone. Twenty healthy participants performed an emotional face task under functional MRI on three occasions: increased serotonin tone following infusion of a selective serotonin reuptake inhibitor (SSRI), decreased serotonin tone following acute tryptophan depletion (ATD) protocol, and no serotonin challenge (control). During the task, participants performed a gender-discrimination task of neutral, fearful or angry facial expressions. Individual variations in neuroticism scores were associated with neural response of subgenual anterior cingulate cortex to fearful facial expressions. The association was however opposite under the two serotoninergic challenges. The fear-related response in this region and individual neuroticism scores correlated negatively during citalopram challenge and positively during ATD. Thus, neuroticism scores were associated with the relative impact of serotonin challenges on fear processing in subgenual anterior cingulate cortex. This finding may link to a neural mechanism for the variable therapeutic effect of SSRI treatment observed in clinical populations.

Predict Disease Progression With Reaction Rate Equation Modeling of Multimodal MRI and PET

Neurodegenerative dementia often has multiple types of underlying pathology, for example, beta-amyloid, misfolded tau, chronic neuroinflammation and neurodegeneration may coexist in Alzheimer’s disease. However, the relationship between them is often unclear, in other words, whether one pathology is upstream or downstream of others can be very difficult to investigate directly. This is partly because the underlying pathology in dementia may precede detectable symptoms by several years if not decades. The time scale associated with disease progression in dementia generally exceeds that in conventional longitudinal imaging studies in humans, so it is difficult to directly observe the temporal ordering of different pathologies. Also, animal studies are not always transferable to patients due to obvious differences between the two systems. To investigate the disease progression and relationships among underlying pathological changes, we propose a novel computational modeling approach for multimodal MRI and PET inspired by reaction rate equation in chemical kinetics. We also discuss the possibility and prerequisites to use cross-sectional data to generate preliminary hypothesis for future longitudinal studies. It has been shown that the rate of change in some biomarkers can be approximated by the average trajectory across patients at different stages of disease severity in cross-sectional studies. The relationship modeled in our approach is akin to that in the control theory, and can be assessed by demonstrating that the presence of one disease related biomarker predicts dynamics in another. We argue that the proposed framework has important implications for trials targeting different pathologies in dementia.

Presymptomatic white matter integrity loss in familial frontotemporal dementia in the GENFI cohort: A cross-sectional diffusion tensor imaging study

Objective

We aimed to investigate mutation-specific white matter (WM) integrity changes in presymptomatic and symptomatic mutation carriers of the C9orf72,MAPT, and GRN mutations by use of diffusion-weighted imaging within the Genetic Frontotemporal dementia Initiative (GENFI) study.

Methods

One hundred and forty mutation carriers (54 C9orf72, 30 MAPT, 56 GRN), 104 presymptomatic and 36 symptomatic, and 115 noncarriers underwent 3T diffusion tensor imaging. Linear mixed effects models were used to examine the association between diffusion parameters and years from estimated symptom onset in C9orf72,MAPT, and GRN mutation carriers versus noncarriers. Post hoc analyses were performed on presymptomatic mutation carriers only, as well as left-right asymmetry analyses on GRN mutation carriers versus noncarriers.

Results

Diffusion changes in C9orf72 mutation carriers are present significantly earlier than both MAPT and GRN mutation carriers - characteristically in the posterior thalamic radiation and more posteriorly located tracts (e.g., splenium of the corpus callosum, posterior corona radiata), as early as 30 years before estimated symptom onset. MAPT mutation carriers showed early involvement of the uncinate fasciculus and cingulum, sparing the internal capsule, whereas involvement of the anterior and posterior internal capsule was found in GRN. Restricting analyses to presymptomatic mutation carriers only, similar - albeit less extensive - patterns were found: posteriorly located WM tracts (e.g., posterior thalamic radiation, splenium of the corpus callosum, posterior corona radiata) in presymptomatic C9orf72, the uncinate fasciculus in presymptomatic MAPT, and the internal capsule (anterior and posterior limbs) in presymptomatic GRN mutation carriers. In GRN, most tracts showed significant left-right differences in one or more diffusion parameter, with the most consistent results being found in the UF, EC, RPIC, and ALIC.

Interpretation

This study demonstrates the presence of early and widespread WM integrity loss in presymptomatic FTD, and suggests a clear genotypic "fingerprint." Our findings corroborate the notion of FTD as a network-based disease, where changes in connectivity are some of the earliest detectable features, and identify diffusion tensor imaging as a potential neuroimaging biomarker for disease-tracking and -staging in presymptomatic to early-stage familial FTD.

Bayesian uncertainty analysis for complex systems biology models: emulation, global parameter searches and evaluation of gene functions

Background

Many mathematical models have now been employed across every area of systems biology. These models increasingly involve large numbers of unknown parameters, have complex structure which can result in substantial evaluation time relative to the needs of the analysis, and need to be compared to observed data of various forms. The correct analysis of such models usually requires a global parameter search, over a high dimensional parameter space, that incorporates and respects the most important sources of uncertainty. This can be an extremely difficult task, but it is essential for any meaningful inference or prediction to be made about any biological system. It hence represents a fundamental challenge for the whole of systems biology.

Methods

Bayesian statistical methodology for the uncertainty analysis of complex models is introduced, which is designed to address the high dimensional global parameter search problem. Bayesian emulators that mimic the systems biology model but which are extremely fast to evaluate are embeded within an iterative history match: an efficient method to search high dimensional spaces within a more formal statistical setting, while incorporating major sources of uncertainty.

Results

The approach is demonstrated via application to a model of hormonal crosstalk in Arabidopsis root development, which has 32 rate parameters, for which we identify the sets of rate parameter values that lead to acceptable matches between model output and observed trend data. The multiple insights into the model’s structure that this analysis provides are discussed. The methodology is applied to a second related model, and the biological consequences of the resulting comparison, including the evaluation of gene functions, are described.

Conclusions

Bayesian uncertainty analysis for complex models using both emulators and history matching is shown to be a powerful technique that can greatly aid the study of a large class of systems biology models. It both provides insight into model behaviour and identifies the sets of rate parameters of interest.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0484-3) contains supplementary material, which is available to authorized users.

Genetic screening in sporadic ALS and FTD

The increasing complexity of the genetic landscape in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) presents a significant resource and physician training challenge. At least 10% of those diagnosed with ALS or FTD are known to carry an autosomal dominant genetic mutation. There is no consensus on what constitutes a positive family history, and ascertainment is unreliable for many reasons. However, symptomatic individuals often wish to understand as much as possible about the cause of their disease, and to share this knowledge with their family. While the right of an individual not to know is a key aspect of patient autonomy, and despite the absence of definitive therapy, many newly diagnosed individuals are likely to elect for genetic testing if offered. It is incumbent on the practitioner to ensure that they are adequately informed, counselled and supported in this decision.

Comparison of Pharmacokinetics of Vardenafil Administered Using an Ultrasonic Nebulizer for Inhalation vs a Single 10-mg Oral Tablet

INTRODUCTION

Delivery of vardenafil (for improvement of erectile function) via the inhaled route of administration may be advantageous in that this avoids extensive first pass metabolism and may therefore increase the bioavailability (hence the reliability of absorption) and shorten the time of pharmacological onset of activity. A unique nebulizer design has been developed by the sponsor (Advanced Medical Institute Pty Ltd) that is capable of delivering relatively large volumes of drug.

AIM

The primary objective of the Phase 1 study was to assess and compare the pharmacokinetics of a single dose of vardenafil 10-mg tablet and a single dose of vardenafil solution administered via inhalation using an ultrasonic nebulizer device. Secondary objective was to assess the safety of vardenafil administered via inhalation using an ultrasonic nebuliser device.

METHODS

Two-part study in healthy volunteers. Dose-ranging study was performed in two subjects to determine the appropriate inhalational dose, followed by an open, randomized, crossover, single dose pharmacokinetic study in 12 subjects, which compared a single 10-mg oral dose to the inhalation dose.

MAIN OUTCOME MEASURES

Cmax, Cmax/Dose, Tmax, ke, t1/2, AUC0-t, AUCt-∞, AUC0-∞, AUC0-∞, AUC0-∞/Dose, and % area extrapolated.

RESULTS

The two treatments are not bioequivalent, with vardenafil absorbed and eliminated faster and with less variability using the nebulizer for drug delivery. Administration via the inhalational route was not associated with any clinically significant changes in blood pressure or heart rate, and no serious adverse events were recorded, demonstrating an acceptable safety profile.

CONCLUSION

To our knowledge, this is the first report of the administration of vardenafil HCl via the pulmonary route of administration. This trial demonstrates that vardenafil HCl may be administered using the ultrasonic nebulizer to reach blood levels comparable with those produced by a vardenafil 10-mg oral tablet, faster and using less drug. This new route of administration may potentially improve the onset of action, reliability, and safety for this class of drug.

Serotonergic modulation of cognition; An acute challenge

Serotonin is well known to affect the multifaceted construct of impulsivity. Lowering brain serotonin levels is shown to increase impulsive choice in delay-discounting tasks (1) but improves response inhibition in stop-signal paradigms. (2) Administration of the antidepressant citalopram in healthy people increases tendency to perform go choices in a Go/No-Go task independent of outcome valence (3). It is rather unclear thought how serotonergic neurotransmission affects several aspects of cognition. We administered a single dose of 20 mg escitalopram, a selective serotonin reuptake inhibitor, to 66 healthy participants, aged 18–45 years old, in a double-blind, randomized, placebo-controlled, parallel-groups study. Acute escitalopram administration had a beneficial effect on inhibitory control with reduced stop-signal reaction time observed in the treatment group. Participants made significantly more errors in a probabilistic learning task and had lower accuracy during the discrimination stage in an instrumental learning task thus indicating a learning impairment. More errors in the CANTAB intra-extra dimensional set shift task were also observed in the escitalopram-treated group. Our findings following acute administration of a clinically relevant dose of escitalopram show a dissociate role for serotonin in modulating cognition mediated by a potentially differential modulation of fronto-striatal loops.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Abstract P4-17-01: YSC's "shady pink elephant” end of life series

Background

Young Survival Coalition (YSC) is the premier organization dedicated to the critical issues confronted by young women diagnosed with breast cancer.Young women diagnosed with metastatic breast cancer (YWMBC) in particular, face unique concerns. As a result of a large survey to its metastatic constituency from September 2013 through February 2014, YSC gained important information about the lack of knowledge and education when it comes to end of life (EOL) planning and decisions. The survey was a result of YSC's Research Think Tank, which included a metastasis work group that identified the psychosocial needs of YWMBC as a priority.

Based on the results of this survey which showed 71% of YWMBC had not made EOL plans, YSC decided that offering education and tools regarding EOL was an important intervention to offer. In doing so, young women affected by breast cancer, young adult cancer survivors, co-survivors and healthcare providers will be better prepared to have difficult conversations by allowing stigma to be removed, intentions to be shared, and plans to be made, all to honor the young woman's wishes.

Methods

YSC created a three part end-of-life series called the “Shady Pink Elephant.” (hereinafter “Series”) Each part featured a subject matter expert and was offered as a Facebook event where the speaker was live-streamed and recorded. YSC also offered free continuing education credits for nurses and social workers. The recorded events are stored on YSC's YouTube channel as enduring material. The three parts include: (a) The Research and Benefit of Introducing Palliative Care Early; (b) Let's Have Dinner and Talk about Death; and (c) The “Nuts and Bolts” of End of Life Planning. YSC collaborated with the University of Louisville and received IRB approval to study the entire series as intervention. The study is in process and will conclude later in 2016.

Results

Nine participated in Series Part One of the live event. For Series Part Two, 31 participated in the live event. In the third and final part, 33 participated in the live event. The three parts housed on YSC's YouTube channel have been viewed a total of 747 times to date: 411 views for part one, 156 views for part two and 180 for part three. Thirty-three sought continuing education credit. Fourteen social workers and 5 nurses contacted the approving organization to receive continuing education credit for Series Part One, and 10 social workers and 1 nurse contacted the approving organization to receive continuing education credit for Series Part Three.

Conclusions

Live-streamed, recorded Facebook events are a novel and forward-thinking mode of programmatic offering. YSC learned through this process that live-streamed events are a feasible way to offer programming that reaches a larger and broader audience of young women affected by breast cancer and their loved ones.

Citation Format: Esser MR, Rowe J, Schapmire T, Lewis S. YSC's "shady pink elephant” end of life series [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-17-01.

Why is there a lower prevalence of chronic immobility in geriatric departments with a high turnover of patients?

There is little information available about the characteristics of patients admitted to geriatric units with high and low turnover rates of patients. It is often suggested that high turnover units do not admit the more physically disabled person. This study set out to investigate whether this view is true. Six geriatric units with different patient discharge rates were investigated. Those units with a high turnover of patients tend to admit more severely immobile people per bed, when compared to those units with below average throughput. Although these immobile people admitted to high turnover units suffered a higher mortality rate, a significantly greater proportion regained the ability to transfer themselves independently from bed to chair and to the toilet.

Increasing patient engagement in rehabilitation activities

Despite evidence that intensive rehabilitation speeds recovery from acute illness, several studies on British rehabilitation units have shown that the time spent by patients in therapeutic activities is low and that levels of 'engagement' are poor. We carried out an observational study of patient activity on four rehabilitation wards for the elderly (51 patients observed at half-hourly intervals between 8 a.m. and 5 p.m. on five successive days).

Patients were found to be engaged in therapeutically useful activities at only 17% of the observation points. When time spent in the therapy departments (where activities were not monitored) was excluded the proportion of useful activities fell to 11%. Similar patterns of activity were seen in all patient subgroups.

An intervention scheme was therefore devised, whereby an hourly activities programme tailored to the needs of each patient was worked out by therapists and ward staff, to be supervised by nurses. One nurse also organized regular group activities. The intervention programme, which required no extra resources, was instituted on two of the four wards.

A repeat survey conducted two months later showed a 55% increase in the proportion of time spent in useful activities on the two intervention wards but no change on the other two wards.

The 'S' test - a preliminary study of an instrument for selecting the most appropriate mobility aid

Objective: To develop and evaluate a qualitative and quantitative instrument for selecting the ideal mobility aid for those with mobility disorders.

Setting: A district general hospital-based geriatric unit.

Subjects: Elderly inpatients and outpatients with mobility disorders.

Interventions: Structured assessments with different mobility aids to select the most suitable.

Outcome measures: Safety, stance, stability, step/stride pattern and speed were considered.

Results: The 'S' test successfully selected an aid for all 49 subjects. For most this aid offered marked improvement in qualitative and quantitative aspects of gait when compared with the subject's usual aid.

Conclusions: The 'S' test is an effective tool for selecting mobility aids within an institutional setting.

Nonlinear interactions in the thalamocortical loop in essential tremor: A model-based frequency domain analysis

There is increasing evidence to suggest that essential tremor has a central origin. Different structures appear to be part of the central tremorogenic network, including the motor cortex, the thalamus and the cerebellum. Some studies using electroencephalogram (EEG) and magnetoencephalography (MEG) show linear association in the tremor frequency between the motor cortex and the contralateral tremor electromyography (EMG). Additionally, high thalamomuscular coherence is found with the use of thalamic local field potential (LFP) recordings and tremulous EMG in patients undergoing surgery for deep brain stimulation (DBS). Despite a well-established reciprocal anatomical connection between the thalamus and cortex, the functional association between the two structures during "tremor-on" periods remains elusive. Thalamic (Vim) LFPs, ipsilateral scalp EEG from the sensorimotor cortex and contralateral tremor arm EMG recordings were obtained from two patients with essential tremor who had undergone successful surgery for DBS. Coherence analysis shows a strong linear association between thalamic LFPs and contralateral tremor EMG, but the relationship between the EEG and the thalamus is much less clear. These measurements were then analyzed by constructing a novel parametric nonlinear autoregressive with exogenous input (NARX) model. This new approach uncovered two distinct and not overlapping frequency "channels" of communication between Vim thalamus and the ipsilateral motor cortex, defining robustly "tremor-on" versus "tremor-off" states. The associated estimated nonlinear time lags also showed non-overlapping values between the two states, with longer corticothalamic lags (exceeding 50ms) in the tremor active state, suggesting involvement of an indirect multisynaptic loop. The results reveal the importance of the nonlinear interactions between cortical and subcortical areas in the central motor network of essential tremor. This work is important because it demonstrates for the first time that in essential tremor the functional interrelationships between the cortex and thalamus should not be sought exclusively within individual frequencies but more importantly between cross-frequency nonlinear interactions. Should our results be successfully reproduced on a bigger cohort of patients with essential tremor, our approach could be used to create an on-demand closed-loop DBS device, able to automatically activate when the tremor is on.