Trafficking of Connexin36 (Cx36) in the early secretory pathway

Gap junctions formed by the major neuronal connexin Cx36 function as electrical synapses in the nervous system and provide unique functions such as synchronizing activities or network oscillations. Although the physiological significance of electrical synapses for neuronal networks is well established, little is known about the pathways that regulate the transport of its main component: Cx36. Here we have used HEK293T cells as an expression system in combination with siRNA and BioID screens to study the transition of Cx36 from the ER to the cis Golgi. Our data indicate that the C-terminal tip of Cx36 is a key factor in this process, mediating binding interactions with two distinct components in the early secretory pathway: the COPII complex and the Golgi stacking protein Grasp55. The C-terminal amino acid valine serves as an ER export signal to recruit COPII cargo receptors Sec24A/B/C at ER exit sites, whereas the PDZ binding motif "SAYV" mediates an interaction with Grasp55. These two interactions have opposing effects in their respective compartments. While Sec24 subunits carry Cx36 out of the ER, Grasp55 stabilizes Cx36 in the Golgi as shown in over expression experiments. These early regulatory steps of Cx36 are expected to be essential for the formation, function, regulation and plasticity of electrical synapses in the developing and mature nervous system.

Cost-effective strategies to knock down genes of interest in the retinas of adult zebrafish

High throughput sequencing has generated an enormous amount of information about the genes expressed in various cell types and tissues throughout the body, and about how gene expression changes over time and in diseased conditions. This knowledge has made targeted gene knockdowns an important tool in screening and identifying the roles of genes that are differentially expressed among specific cells of interest. While many approaches are available and optimized in mammalian models, there are still several limitations in the zebrafish model. In this article, we describe two approaches to target specific genes in the retina for knockdown: cell-penetrating, translation-blocking Vivo-Morpholino oligonucleotides and commercially available lipid nanoparticle reagents to deliver siRNA. We targeted expression of the PCNA gene in the retina of a P23H rhodopsin transgenic zebrafish model, in which rapidly proliferating progenitor cells replace degenerated rod photoreceptors. Retinas collected 48 h after intravitreal injections in adult zebrafish reveal that both Vivo-Morpholinos and lipid encapsulated siRNAs were able to successfully knock down expression of PCNA. However, only retinas injected with Vivo-Morpholinos showed a significant decrease in the formation of P23H rhodopsin-expressing rods, a downstream effect of PCNA inhibition. Surprisingly, Vivo-Morpholinos were able to exit the injected eye and enter the contralateral non-injected eye to inhibit PCNA expression. In this article we describe the techniques, concentrations, and considerations we found necessary to successfully target and inhibit genes through Vivo-Morpholinos and lipid encapsulated siRNAs.

Long-term results of ablation index guided atrial fibrillation ablation: insights after 5+ years of follow-up from the MPH AF Ablation Registry

Background

Catheter ablation (CA) for symptomatic atrial fibrillation (AF) offers the best outcomes for patients. Despite the benefits of CA, a significant proportion of patients suffer a recurrence; hence, there is scope to potentially improve outcomes through technical innovations such as ablation index (AI) guidance during AF ablation. We present real-world 5-year follow-up data of AI-guided pulmonary vein isolation.

Methods

We retrospectively followed 123 consecutive patients who underwent AI-guided CA shortly after its introduction to routine practice. Data were collected from the MPH AF Ablation Registry with the approval of the institutional research board.

Results

Our patient cohort was older, with higher BMI, greater CHA2DS2-VASc scores, and larger left atrial sizes compared to similar previously published cohorts, while gender balance and other characteristics were similar. The probability of freedom from atrial arrhythmia with repeat procedures is as follows: year 1: 0.95, year 2: 0.92, year 3: 0.85, year 4: 0.79, and year 5: 0.72. Age >75 years (p = 0.02, HR: 2.7, CI: 1.14-6.7), BMI >35 kg/m2 (p = 0.0009, HR: 4.6, CI: 1.8-11.4), and left atrial width as measured on CT in the upper quartile (p = 0.04, HR: 2.5, CI: 1-5.7) were statistically significant independent predictors of recurrent AF.

Conclusion

AI-guided CA is an effective treatment for AF, with 95.8% of patients remaining free from atrial arrhythmia at 1 year and 72.3% at 5 years, allowing for repeat procedures. It is safe with a low major complication rate of 1.25%. Age >75 years, BMI >35 kg/m2, and markedly enlarged atria were associated with higher recurrence rates.

Genetic risks of Alzheimer's by APOE and MAPT on cortical morphology in young healthy adults

Genetic risk factors such as APOE ε4 and MAPT (rs242557) A allele are associated with amyloid and tau pathways and grey matter changes at both early and established stages of Alzheimer's disease, but their effects on cortical morphology in young healthy adults remain unclear. A total of 144 participants aged from 18 to 24 underwent 3T MRI and genotyping for APOE and MAPT to investigate unique impacts of these genetic risk factors in a cohort without significant comorbid conditions such as metabolic and cardiovascular diseases. We segmented the cerebral cortex into 68 regions and calculated the cortical area, thickness, curvature and folding index for each region. Then, we trained machine learning models to classify APOE and MAPT genotypes using these morphological features. In addition, we applied a growing hierarchical self-organizing maps algorithm, which clustered the 68 regions into 4 subgroups representing different morphological patterns. Then, we performed general linear model analyses to estimate the interaction between APOE and MAPT on cortical patterns. We found that the classifiers using all cortical features could accurately classify individuals carrying genetic risks of dementia outperforming each individual feature alone. APOE ε4 carriers had a more convoluted and thinner cortex across the cerebral cortex. A similar pattern was found in MAPT A allele carriers only in the regions that are vulnerable for early tau pathology. With the clustering analysis, we found a synergetic effect between APOE ε4 and MAPT A allele, i.e. carriers of both risk factors showed the most deviation of cortical pattern from the typical pattern of that cluster. Genetic risk factors of dementia by APOE ε4 and MAPT (rs242557) A allele were associated with variations of cortical morphology, which can be observed in young healthy adults more than 30 years before Alzheimer's pathology is likely to occur and 50 years before dementia symptoms may begin.

Long wavelength-sensing cones of zebrafish retina exhibit multiple layers of transcriptional heterogeneity

Introduction

Understanding how photoreceptor genes are regulated is important for investigating retinal development and disease. While much is known about gene regulation in cones, the mechanism by which tandemly-replicated opsins, such as human long wavelength-sensitive and middle wavelength-sensitive opsins, are differentially regulated remains elusive. In this study, we aimed to further our understanding of transcriptional heterogeneity in cones that express tandemly-replicated opsins and the regulation of such differential expression using zebrafish, which express the tandemly-replicated opsins lws1 and lws2.

Methods

We performed bulk and single cell RNA-Seq of LWS1 and LWS2 cones, evaluated expression patterns of selected genes of interest using multiplex fluorescence in situ hybridization, and used exogenous thyroid hormone (TH) treatments to test selected genes for potential control by thyroid hormone: a potent, endogenous regulator of lws1 and lws2 expression.

Results

Our studies indicate that additional transcriptional differences beyond opsin expression exist between LWS1 and LWS2 cones. Bulk RNA-Seq results showed 95 transcripts enriched in LWS1 cones and 186 transcripts enriched in LWS2 cones (FC > 2, FDR < 0.05). In situ hybridization results also reveal underlying heterogeneity within the lws1- and lws2-expressing populations. This heterogeneity is evident in cones of mature zebrafish, and further heterogeneity is revealed in transcriptional responses to TH treatments.

Discussion

We found some evidence of coordinate regulation of lws opsins and other genes by exogenous TH in LWS1 vs. LWS2 cones, as well as evidence of gene regulation not mediated by TH. The transcriptional differences between LWS1 and LWS2 cones are likely controlled by multiple signals, including TH.

Illuminating neurodegeneration: a future perspective on near-infrared spectroscopy in dementia research

SIGNIFICANCE

Dementia presents a global healthcare crisis, and neuroimaging is the main method for developing effective diagnoses and treatments. Yet currently, there is a lack of sensitive, portable, and low-cost neuroimaging tools. As dementia is associated with vascular and metabolic dysfunction, near-infrared spectroscopy (NIRS) has the potential to fill this gap.

AIM

This future perspective aims to briefly review the use of NIRS in dementia to date and identify the challenges involved in realizing the full impact of NIRS for dementia research, including device development, study design, and data analysis approaches.

APPROACH

We briefly appraised the current literature to assess the challenges, giving a critical analysis of the methods used. To assess the sensitivity of different NIRS device configurations to the brain with atrophy (as is common in most forms of dementia), we performed an optical modeling analysis to compare their cortical sensitivity.

RESULTS

The first NIRS dementia study was published in 1996, and the number of studies has increased over time. In general, these studies identified diminished hemodynamic responses in the frontal lobe and altered functional connectivity in dementia. Our analysis showed that traditional (low-density) NIRS arrays are sensitive to the brain with atrophy (although we see a mean decrease of 22% in the relative brain sensitivity with respect to the healthy brain), but there is a significant improvement (a factor of 50 sensitivity increase) with high-density arrays.

CONCLUSIONS

NIRS has a bright future in dementia research. Advances in technology - high-density devices and intelligent data analysis-will allow new, naturalistic task designs that may have more clinical relevance and increased reproducibility for longitudinal studies. The portable and low-cost nature of NIRS provides the potential for use in clinical and screening tests.

Path integration selectively predicts midlife risk of Alzheimer's disease

The entorhinal cortex (EC) is the first cortical region to exhibit neurodegeneration in Alzheimer's disease (AD), associated with EC grid cell dysfunction. Given the role of grid cells in path integration, we predicted that path integration impairment would represent the first behavioural change in adults at-risk of AD. Using immersive virtual reality, we found that midlife path integration impairments predicted both hereditary and physiological AD risk, with no corresponding impairment on tests of episodic memory or other spatial behaviours. Impairments related to poorer angular estimation and were associated with hexadirectional grid-like fMRI signal in the posterior-medial EC. These results indicate that altered path integration may represent the transition point from at-risk state to disease onset in AD, prior to impairment in other cognitive domains.

Can early phase cardiac [123I]mIBG images be used to diagnose Lewy body disease?

PURPOSE

Some studies have suggested that cardiac [123I]metaiodobenzylguanidine images obtained 15-20 min after tracer administration are as accurate for dementia with Lewy bodies (DLB) diagnosis as standard images acquired after a delay of 3-4 h; some suggest delayed imaging is preferable. We compare early and delayed heart-to-mediastinum ratios (HMR) in a well-characterised research dataset and make recommendations for clinical practice.

METHODS

Images were acquired using a Siemens gamma camera with medium energy collimators. Early images were obtained at 20 min and delayed at 4 h (± 30) min. In total 167 pairs of images were reviewed: 30 controls, 39 people with dementia and 98 with mild cognitive impairment. HMR normal cutoff values derived from control data were ≥2.10 for early imaging and ≥1.85 for delayed.

RESULTS

HMR tended to drop between early and delayed for abnormal images, but increase for normal images. Histograms of early and delayed HMR showed a slightly better separation of results into two groups for delayed imaging. Accuracy results were slightly higher for delayed imaging than early imaging (73 vs. 77%), sensitivity 63 vs. 65% and specificity 82 vs. 88%. However, this was not statistically significant - in total only 8/167 (5%) of scans changed designation between early and delayed imaging.

CONCLUSION

We suggest that a delayed image could be acquired only if the early result is borderline. This removes the need for delayed imaging in about 70% of patients. Adopting this protocol in clinical practice would reduce the time most patients have to wait and could free up scanner time.

Blood pressure and heart rate responses to orthostatic challenge and Valsalva manoeuvre in mild cognitive impairment with Lewy bodies

OBJECTIVES

Orthostatic hypotension is a common feature of normal ageing, and age-related neurodegenerative diseases, in particular the synucleinopathies including dementia with Lewy bodies. Orthostatic hypotension and other abnormal cardiovascular responses may be early markers of Lewy body disease. We aimed to assess whether abnormal blood pressure and heart rate responses to orthostatic challenge and Valsalva manoeuvre would be more common in mild cognitive impairment with Lewy bodies (MCI-LB) than MCI due to Alzheimer's disease (MCI-AD).

METHODS

MCI patients (n = 89) underwent longitudinal clinical assessment with differential classification of probable MCI-LB, possible MCI-LB, or MCI-AD, with objective autonomic function testing at baseline. Blood pressure and heart rate responses to active stand and Valsalva manoeuvre were calculated from beat-to-beat cardiovascular data, with abnormalities defined by current criteria, and age-adjusted group differences estimated with logistic models.

RESULTS

Orthostatic hypotension and abnormal heart rate response to orthostatic challenge were not more common in probable MCI-LB than MCI-AD. Heart rate abnormalities were likewise not more common in response to Valsalva manoeuvre in probable MCI-LB. An abnormal blood pressure response to Valsalva (delayed return to baseline/absence of overshoot after release of strain) was more common in probable MCI-LB than MCI-AD. In secondary analyses, magnitude of blood pressure drop after active stand and 10-s after release of Valsalva strain were weakly correlated with cardiac sympathetic denervation.

CONCLUSIONS

Probable MCI-LB may feature abnormal blood pressure response to Valsalva, but orthostatic hypotension is not a clear distinguishing feature from MCI-AD.

Assessment of autonomic symptoms may assist with early identification of mild cognitive impairment with Lewy bodies

OBJECTIVES

Autonomic symptoms are a common feature of the synucleinopathies, and may be a distinguishing feature of prodromal Lewy body disease. We aimed to assess whether the cognitive prodrome of dementia with Lewy bodies, mild cognitive impairment (MCI) with Lewy bodies (MCI-LB), would have more severe reported autonomic symptoms than cognitively healthy older adults, with MCI due to Alzheimer's disease (MCI-AD) also included for comparison. We also aimed to assess the utility of an autonomic symptom scale in differentiating MCI-LB from MCI-AD.

METHODS

Ninety-three individuals with MCI and 33 healthy controls were assessed with the Composite Autonomic Symptom Score 31-item scale (COMPASS). Mild cognitive impairment patients also underwent detailed clinical assessment and differential classification of MCI-AD or MCI-LB according to current consensus criteria. Differences in overall COMPASS score and individual symptom sub-scales were assessed, controlling for age.

RESULTS

Age-adjusted severity of overall autonomic symptomatology was greater in MCI-LB (Ratio = 2.01, 95% CI: 1.37-2.96), with higher orthostatic intolerance and urinary symptom severity than controls, and greater risk of gastrointestinal and secretomotor symptoms. MCI-AD did not have significantly higher autonomic symptom severity than controls overall. A cut-off of 4/5 on the COMPASS was sensitive to MCI-LB (92%) but not specific to this (42% specificity vs. MCI-AD and 52% vs. healthy controls).

CONCLUSIONS

Mild cognitive impairment with Lewy bodies had greater autonomic symptom severity than normal ageing and MCI-AD, but such autonomic symptoms are not a specific finding. The COMPASS-31 may therefore have value as a sensitive screening test for early-stage Lewy body disease.

Challenges and opportunities for conducting a vaccine trial during the COVID-19 pandemic in the United Kingdom

The COVID-19 pandemic has resulted in unprecedented challenges for healthcare systems worldwide. It has also stimulated research in a wide range of areas including rapid diagnostics, novel therapeutics, use of technology to track patients and vaccine development. Here, we describe our experience of rapidly setting up and delivering a novel COVID-19 vaccine trial, using clinical and research staff and facilities in three National Health Service Trusts in Cambridgeshire, United Kingdom. We encountered and overcame a number of challenges including differences in organisational structures, research facilities available, staff experience and skills, information technology and communications infrastructure, and research training and assessment procedures. We overcame these by setting up a project team that included key members from all three organisations that met at least daily by teleconference. This group together worked to identify the best practices and procedures and to harmonise and cascade these to the wider trial team. This enabled us to set up the trial within 25 days and to recruit and vaccinate the participants within a further 23 days. The lessons learned from our experiences could be used to inform the conduct of clinical trials during a future infectious disease pandemic or public health emergency.

The effectiveness and cost-effectiveness of assistive technology and telecare for independent living in dementia: a randomised controlled trial

Objectives

The use of assistive technology and telecare (ATT) has been promoted to manage risks associated with independent living in people with dementia but with little evidence for effectiveness.

Methods

Participants were randomly assigned to receive an ATT assessment followed by installation of all appropriate ATT devices or limited control of appropriate ATT. The primary outcomes were time to institutionalisation and cost-effectiveness. Key secondary outcomes were number of incidents involving risks to safety, burden and stress in family caregivers and quality of life.

Results

Participants were assigned to receive full ATT (248 participants) or the limited control (247 participants). After adjusting for baseline imbalance of activities of daily living score, HR for median pre-institutionalisation survival was 0.84; 95% CI, 0.63 to 1.12; P = 0.20. There were no significant differences between arms in health and social care (mean -£909; 95% CI, -£5,336 to £3,345, P = 0.678) and societal costs (mean -£3,545; 95% CI, -£13,914 to £6,581, P = 0.499). ATT group members had reduced participant-rated quality-adjusted life years (QALYs) at 104 weeks (mean − 0.105; 95% CI, −0.204 to −0.007, P = 0.037) but did not differ in QALYs derived from proxy-reported EQ-5D.

Discussion

Fidelity of the intervention was low in terms of matching ATT assessment, recommendations and installation. This, however, reflects current practice within adult social care in England.

Conclusions

Time living independently outside a care home was not significantly longer in participants who received full ATT and ATT was not cost-effective. Participants with full ATT attained fewer QALYs based on participant-reported EQ-5D than controls at 104 weeks.

Reducing Inappropriate Overutilization of the Massive Transfusion Protocol

Introduction/Objective

Massive transfusion protocols (MTPs) make it possible to deliver blood products to exsanguinating patients in an efficient, sustained, and immediate manner. However, overutilization of MTPs continues to remain a significant problem for hospital blood banks. The study aims to address the characteristics of possibly inappropriate MTP activations during the first phase (cooler) at a level 1 trauma academic medical center.

Methods

This was a retrospective review of 328 phase 1 MTPs out of 696 total MTPs performed during a two-year period (Jan 1, 2017 and Dec 31, 2018) and divided into three categories: trauma, non-trauma surgery, and medicine services. We assumed that a possibly inappropriate MTP for trauma cases would show an Assessment of Blood Component (ABC) score of 1 or less and physicians used clinical discretion. For possibly inappropriate MTP non- trauma surgical and medicine cases, we devised a new system where we looked at only whether the blood pressure was equal to or less than 90 mm Hg and/or the pulse was greater than or equal to 120 beats per minute. If there was a score of 0 where there were neither vital sign criteria, then the MTP was considered possibly inappropriate.

Results

For trauma service, there were 43/168 (25.6%) cases that had an ABC score of 0, 49/168 (29.2%) cases that had an ABC score of 1, 53/168 (31.5%) cases that had an ABC score of 2, 21/168 (12.5%) cases that had an ABC score of 3, and only 2/168 (1.2%) case that had an ABC score of 4. Non-trauma surgery service had 31/51 (60.8%) cases with a new score of 0, 20/51 (39.2%) cases with a new score of 1, and 0/51 (0%) cases with a new score of 2. Medicine services had 57/109 (52.3%) patients with a new score of 0, 47/109 (43.1%) patients with a new score of 1, and 5/109 (4.6%) patients with a new score of 2. Non-trauma surgery service had the greatest possibly inappropriate MTP activations [31/51 cases (60.8%)], followed by trauma [92/168 (54.8%) cases] and medicine [57/109 (52.3%) cases].

Conclusion

Our study shows greater overutilization with MTPs using clinical judgment than with using the ABC criteria. Non-trauma surgery service had the greatest number of possibly inappropriate MTP activations at our hospital without having a significantly abnormal pulse or blood pressure. While ABC criteria is already liberal for activating an MTP, physician discretion appears to be more liberal in activating a possibly inappropriate MTP.

Research with older people in a world with COVID-19: identification of current and future priorities, challenges and opportunities

Older people are disproportionately affected by the COVID-19 pandemic, which has had a profound impact on research as well as clinical service delivery. This commentary identifies key challenges and opportunities in continuing to conduct research with and for older people, both during and after the current pandemic. It shares opinions from responders to an international survey, a range of academic authors and opinions from specialist societies. Priorities in COVID-19 research include its specific presentation in older people, consequences for physical, cognitive and psychological health, treatments and vaccines, rehabilitation, supporting care homes more effectively, the impact of social distancing, lockdown policies and system reconfiguration to provide best health and social care for older people. COVID-19 research needs to be inclusive, particularly involving older people living with frailty, cognitive impairment or multimorbidity, and those living in care homes. Non-COVID-19 related research for older people remains of critical importance and must not be neglected in the rush to study the pandemic. Profound changes are required in the way that we design and deliver research for older people in a world where movement and face-to-face contact are restricted, but we also highlight new opportunities such as the ability to collaborate more widely and to design and deliver research efficiently at scale and speed.

A Zebrafish Model of Retinitis Pigmentosa Shows Continuous Degeneration and Regeneration of Rod Photoreceptors

More than 1.5 million people suffer from Retinitis Pigmentosa, with many experiencing partial to complete vision loss. Regenerative therapies offer some hope, but their development is challenged by the limited regenerative capacity of mammalian model systems. As a step toward investigating regenerative therapies, we developed a zebrafish model of Retinitis Pigmentosa that displays ongoing regeneration. We used Tol2 transgenesis to express mouse rhodopsin carrying the P23H mutation and an epitope tag in zebrafish rod photoreceptors. Adult and juvenile fish were examined by immunofluorescence, TUNEL and BrdU incorporation assays. P23H transgenic fish expressed the transgene in rods from 3 days post fertilization onward. Rods expressing the mutant rhodopsin formed very small or no outer segments and the mutant protein was delocalized over the entire cell. Adult fish displayed thinning of the outer nuclear layer (ONL) and loss of rod outer segments, but retained a single, sparse row of rods. Adult fish displayed ongoing apoptotic cell death in the ONL and an abundance of proliferating cells, predominantly in the ONL. There was a modest remodeling of bipolar and Müller glial cells. This transgenic fish will provide a useful model system to study rod photoreceptor regeneration and integration.

Synaptic Loss in Primary Tauopathies Revealed by [11 C]UCB-J Positron Emission Tomography

BACKGROUND

Synaptic loss is a prominent and early feature of many neurodegenerative diseases.

OBJECTIVES

We tested the hypothesis that synaptic density is reduced in the primary tauopathies of progressive supranuclear palsy (PSP) (Richardson's syndrome) and amyloid-negative corticobasal syndrome (CBS).

METHODS

Forty-four participants (15 CBS, 14 PSP, and 15 age-/sex-/education-matched controls) underwent PET with the radioligand [11 C]UCB-J, which binds to synaptic vesicle glycoprotein 2A, a marker of synaptic density; participants also had 3 Tesla MRI and clinical and neuropsychological assessment.

RESULTS

Nine CBS patients had negative amyloid biomarkers determined by [11 C]PiB PET and hence were deemed likely to have corticobasal degeneration (CBD). Patients with PSP-Richardson's syndrome and amyloid-negative CBS were impaired in executive, memory, and visuospatial tasks. [11 C]UCB-J binding was reduced across frontal, temporal, parietal, and occipital lobes, cingulate, hippocampus, insula, amygdala, and subcortical structures in both PSP and CBD patients compared to controls (P < 0.01), with median reductions up to 50%, consistent with postmortem data. Reductions of 20% to 30% were widespread even in areas of the brain with minimal atrophy. There was a negative correlation between global [11 C]UCB-J binding and the PSP and CBD rating scales (R = -0.61, P < 0.002; R = -0.72, P < 0.001, respectively) and a positive correlation with the revised Addenbrooke's Cognitive Examination (R = 0.52; P = 0.01).

CONCLUSIONS

We confirm severe synaptic loss in PSP and CBD in proportion to disease severity, providing critical insight into the pathophysiology of primary degenerative tauopathies. [11 C]UCB-J may facilitate treatment strategies for disease-modification, synaptic maintenance, or restoration. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Calmodulin Binding to Connexin 35: Specializations to Function as an Electrical Synapse

Calmodulin binding is a nearly universal property of gap junction proteins, imparting a calcium-dependent uncoupling behavior that can serve in an emergency to decouple a stressed cell from its neighbors. However, gap junctions that function as electrical synapses within networks of neurons routinely encounter large fluctuations in local cytoplasmic calcium concentration; frequent uncoupling would be impractical and counterproductive. We have studied the properties and functional consequences of calmodulin binding to the electrical synapse protein Connexin 35 (Cx35 or gjd2b), homologous to mammalian Connexin 36 (Cx36 or gjd2). We find that specializations in Cx35 calmodulin binding sites make it relatively impervious to moderately high levels of cytoplasmic calcium. Calmodulin binding to a site in the C-terminus causes uncoupling when calcium reaches low micromolar concentrations, a behavior prevented by mutations that eliminate calmodulin binding. However, milder stimuli promote calcium/calmodulin-dependent protein kinase II activity that potentiates coupling without interference from calmodulin binding. A second calmodulin binding site in the end of the Cx35 cytoplasmic loop, homologous to a calmodulin binding site present in many connexins, binds calmodulin with very low affinity and stoichiometry. Together, the calmodulin binding sites cause Cx35 to uncouple only at extreme levels of intracellular calcium.

TECRA Listeria Visual Immunoassay (TLVIA) for Detection of Listeria in Foods: Collaborative Study

A collaborative study involving 26 laboratories and 5 food types was performed to compare the TECRA Listeria Visual Immunoassay (TLVIA) with standard culture methods. Three foods (lettuce, ice cream, and fish fillets), under the jurisdiction of the U.S. Food and Drug Administration, and 2 foods (cooked chicken and cooked ground turkey), under the jurisdiction of the U.S. Department of Agriculture, were used to determine the effectiveness of the TLVIA. Of the 900 samples tested, 300 were inoculated with low levels (1-5 cells/25 g) of Listeria spp. and 300 were inoculated with high levels of Listeria spp. (10-50 cells/25 g). Method agreement between the conventional culture methods and TLVIA (visual) was 94.7%. Method agreement between the conventional culture methods and TLVIA (reader) was 93.6%. The colorimetric polyclonal enzyme immunoassay (TLVIA) for detection of Listeria in foods has been adopted first action by AOAC INTERNATIONAL.

Calcium Imaging with Super-Resolution Radial Fluctuations

Calcium signals act as a ubiquitous secondary messenger in regulating many body functions. The detection of calcium microdomain signals is greatly facilitated by the existence of biomarker-targeted fluorescent probes. In this study, SRRF (super-resolution radial fluctuations) algorithm were used to compare the loci and the intensity of fluorescent probes before and after SRRF analysis. The implementation of SRRF algorithm was aimed for automatically resolving delicate and small calcium signals (to avoid the overlapped loci) on original images. For assessing the spatial accuracy of image intensity, immunofluorescence staining of retina cryostat slice for connexin 36 (Cx36) was microscopically imaged with or without the successive SRRF reconstruction. For characterizing the temporal association between SRRF and non-SRRF images, the changes of Cx36-GCaMP calcium indicator were recorded from transfected HeLa cells in response to the transient puffing of ionomycin. Image processing and analyses were conducted with Image J and Matlab. Through this study, SRRF reconstruction was found to confer an accurate measure for the identification of subcellular molecules, such as gap junctions. Compared with the conventional imaging, SRRF reconstruction generated better image resolution for the precise registration of individual signals. Temporally, the ratios of change in fluorescence intensity between SRRF and non-SRRF images were significantly correlated in the presence or absence of the subtraction of high background intensity. Quantitatively, the ratios of change in fluorescence intensity between SRRF and non-SRRF images with or without background subtraction were also significantly correlated. The merit of SRRF application on calcium live imaging was validated with the reporter gene system we worked on.

Synthesis, analytical characterization, and monoamine transporter activity of the new psychoactive substance 4-methylphenmetrazine (4-MPM), with differentiation from its ortho- and meta- positional isomers

The availability of new psychoactive substances (NPS) on the recreational drug market continues to create challenges for scientists in the forensic, clinical and toxicology fields. Phenmetrazine (3-methyl-2-phenylmorpholine) and an array of its analogs form a class of psychostimulants that are well documented in the patent and scientific literature. The present study reports on two phenmetrazine analogs that have been encountered on the NPS market following the introduction of 3-fluorophenmetrazine (3-FPM), namely 4-methylphenmetrazine (4-MPM), and 3-methylphenmetrazine (3-MPM). This study describes the syntheses, analytical characterization, and pharmacological evaluation of the positional isomers of MPM. Analytical characterizations employed various chromatographic, spectroscopic, and mass spectrometric platforms. Pharmacological studies were conducted to assess whether MPM isomers might display stimulant-like effects similar to the parent compound phenmetrazine. The isomers were tested for their ability to inhibit uptake or stimulate release of tritiated substrates at dopamine, norepinephrine and serotonin transporters using in vitro transporter assays in rat brain synaptosomes. The analytical characterization of three vendor samples revealed the presence of 4-MPM in two of the samples and 3-MPM in the third sample, which agreed with the product label. The pharmacological findings suggest that 2-MPM and 3-MPM will exhibit stimulant properties similar to the parent compound phenmetrazine, whereas 4-MPM may display entactogen properties more similar to 3,4-methylenedioxymethamphetamine (MDMA). The combination of test purchases, analytical characterization, targeted organic synthesis, and pharmacological evaluation of NPS and their isomers is an effective approach for the provision of data on these substances as they emerge in the marketplace.

Pregnancy diet and offspring asthma risk over a 10-year period: the Lifeways Cross Generation Cohort Study, Ireland

OBJECTIVE

The association of maternal pregnancy diet with offspring asthma risk have been reported. However, literature on longitudinal patterns of asthma risk relative to intrauterine nutrient exposure is limited. We aimed to establish whether vegetable, oily fish and vitamin D intake during pregnancy are associated with childhood asthma risk over a 10-year period in the Irish Republic.

DESIGN

Mother-child pairs (n=897) from the Lifeways prospective birth cohort, with data on nutrient intake during pregnancy and asthma status, respectively, were eligible for inclusion in the analysis. Data on socioeconomic and morbidity indicators over 10 years of follow-up on mothers and the index child were collected through self-administered questionnaires. Asthma status as diagnosed by the general practitioner at any time point over 10 years was related to maternal vegetable, oily fish and vitamin D intake during pregnancy, while adjusting for gestational age, socioeconomic status, smoking at delivery, breast feeding, season of birth and supplement use. Data were modelled with a marginal model on correlated observations over time within individuals.

RESULTS

In the fully adjusted model, asthma was inversely associated with higher daily average intake of oily fish (OR 0.23 per serving/day, 95% CI 0.04 to 1.41) and of vegetables (OR 0.96 per serving/day, 95% CI 0.88 to 1.05), but the confidence limits overlapped 1. A higher daily vitamin D intake was associated with reduced odds of asthma (OR 0.93 per μg/day, 95% CI 0.89 to 0.98).

CONCLUSION

This analysis suggests higher daily average intake of vitamin D in pregnancy is associated with asthma risk in offspring over the first 10 years of life.

Abstract 153: The Preserve Trial: Intensive Blood Pressure Lowering and Cerebral Blood Flow in Small Vessel Disease

Background and Aims: In patients with severe cerebral small vessel disease (SVD), in whom both cerebral blood flow and cerebral autoregulation are reduced, intensive BP lowering might reduce cerebral blood flow (CBF) and increase the rate of white matter hyperintensity (WMH) progression. In an RCT we determined the effect of intensive BP lowering on CBF in lacunar stroke with confluent WMH.

Method: In the PRESERVE trial Perfusion sub-study, patients from 2 sites with MRI confirmed symptomatic lacunar infarct and confluent WMH were randomised to “normal” (systolic=130-140mmHg, N=33) versus “intensive” (systolic=<125mmHg, N=29) BP targets. CBF was determined using arterial spin labelling; the primary end point was change in global CBF between baseline and 3 months. Linear regression was performed comparing change in CBF against change in BP. Analyses controlled for site.

Results: Mean(SD) systolic BP reduced by 8(12) and 27(17)mmHg in the standard/intensive groups, respectively (difference between groups p <0.001) with achieved BP of 141(13) and 126(10) mmHg respectively. Baseline global CBF was 32(10) and 31(10)ml/min/100g in the standard/intensive groups. There was no difference in change in global CBF between treatment arms: standard, mean(SD) (ml/min/100g)= -0.46 (9.39); intensive, 0.73 (8.62), p =0.63. No differences were observed when analysis examined grey or white matter only, or was confined to those achieving target BP. Change in CBF did not have a significant association with change in systolic or diastolic BP.

Conclusion: Intensive BP lowering did not reduce CBF in severe SVD characterised by lacunar stroke and confluent WMH. This suggests intensive CBF reduction is unlikely to accelerate WMH progression.

Associations of Demographic Factors and Tobacco Use With Progesterone and Estradiol During Pregnancy

OBJECTIVE

To evaluate the association of biochemically validated prenatal tobacco use with serum progesterone and estradiol in the second trimester of pregnancy, controlling for demographic and personal factors.

STUDY DESIGN

This secondary analysis of a multicenter longitudinal study included 114 women with singleton pregnancies. Multiple regression analysis assessed whether prenatal tobacco use was related to hormone levels during the second trimester, controlling for covariates (age, body mass index, and race or ethnicity, with gestational age added to subsequent models).

RESULT

In the initial regressions, tobacco users had significantly lower progesterone level compared with nonsmokers (p = .037), while estradiol was unrelated to prenatal tobacco use. Women with greater body mass index also had significantly lower progesterone (p = .028), but body mass index was unrelated to estradiol. With gestational age as an additional covariate, prenatal tobacco use was no longer a significant predictor of progesterone, but both body mass index and gestational age were significant (F = 10.6, p < .001, R 2 = 0.35). For estradiol, the overall regression of estradiol on age, body mass index, and race or ethnicity was not significant (F = 1.2, p = .31). With gestational age added to the model, the overall model was significant (F = 7.2, p < .001, R 2 = 0.27).

CONCLUSION

This study provides additional evidence that prenatal tobacco use may influence lower serum progesterone during the second trimester. This is of particular concern given the link between depressed progesterone activity and risk for preterm birth.

Structural neuroimaging in preclinical dementia: From microstructural deficits and grey matter atrophy to macroscale connectomic changes

The last decade has witnessed a proliferation of neuroimaging studies characterising brain changes associated with Alzheimer's disease (AD), where both widespread atrophy and 'signature' brain regions have been implicated. In parallel, a prolonged latency period has been established in AD, with abnormal cerebral changes beginning many years before symptom onset. This raises the possibility of early therapeutic intervention, even before symptoms, when treatments could have the greatest effect on disease-course modification. Two important prerequisites of this endeavour are (1) accurate characterisation or risk stratification and (2) monitoring of progression using neuroimaging outcomes as a surrogate biomarker in those without symptoms but who will develop AD, here referred to as preclinical AD. Structural neuroimaging modalities have been used to identify brain changes related to risk factors for AD, such as familial genetic mutations, risk genes (for example apolipoprotein epsilon-4 allele), and/or family history. In this review, we summarise structural imaging findings in preclinical AD. Overall, the literature suggests early vulnerability in characteristic regions, such as the medial temporal lobe structures and the precuneus, as well as white matter tracts in the fornix, cingulum and corpus callosum. We conclude that while structural markers are promising, more research and validation studies are needed before future secondary prevention trials can adopt structural imaging biomarkers as either stratification or surrogate biomarkers.

Rare Earth Doped Silica Nanoparticles via Thermolysis of a Single Source Metallasilsesquioxane Precursor

Rare earth metal doped silica nanoparticles have significant advantages over traditional organic dyes and quantum dots. Silsesquioxanes are promising precursors in the production of silica nanoparticles by thermolysis, due to their structural similarities with silica materials. This manuscript describes the production of a new Eu3+-based metallasilsesquioxane species and its use as a single source precursor in the thermolytic production of luminescent rare earth metal doped silica nanoparticles with characteristic emission in the visible region of the spectrum.

Lessons from a pilot and feasibility randomised trial in depression (Blood pressure Rapid Intensive Lowering And Normal Treatment for Mood and cognition in persistent depression (BRILiANT mood study))

BACKGROUND

The blood pressure rapid intensive lowering and normal treatment for mood and cognition in persistent depression (BRILiANT mood study) was devised as a pilot study to investigate the feasibility and safety of intensive blood pressure lowering as treatment for persistent mood and cognitive symptoms in older adults with major depressive disorder and to assess the availability of this population for recruitment. In addition, the relationship between reduced blood pressure and the change in cerebral blood flow and mood was to be investigated.

METHODS

A single centre pilot randomised controlled trial (RCT), with two parallel groups of intensive or normal treatment for hypertension, recruiting from primary and secondary care and newspaper advert, with an aim of recruiting 66 participants, was observed in this study. At the end of the recruitment period, in order to explore the reasons for failure to recruit to target, surveys were developed and issued to those involved in recruitment.

RESULTS

Recruitment rates were lower than expected which led to the study being expanded to further areas and opened to self-referral via advertisement. However, because of better management of hypertension due to changes in the UK Quality and Outcomes Framework guidelines for blood pressure treatment, few eligible patients were identified and the study closed at the end of the recruitment period, with 13 participants consenting, but 12 failing screening resulting in one recruited participant.

CONCLUSIONS

Overall, the BRILiANT mood study was found not to be feasible, and results suggest that the expected patient population no longer exists. To overcome such recruitment difficulties, a prompt commencement of a study after funding so no relevant care changes occur might help prevent similar problems in future studies. In addition, self-referral, in this case via advertisement in papers, may be a useful tool to increase response rate. When recruiting in primary care, direct access to primary care databases, in a secure and anonymised way, may enable more effective screening. Ultimately, the BRILiANT mood study was shown not to be feasible; this was a useful conclusion from this pilot study.

TRIAL REGISTRATION

ISRCTN 64524251; UKCRN Portfolio No: 13284.

Circadian clock control of connexin36 phosphorylation in retinal photoreceptors of the CBA/CaJ mouse strain

The gap-junction-forming protein connexin36 (Cx36) represents the anatomical substrate of photoreceptor electrical coupling in mammals. The strength of coupling is directly correlated to the phosphorylation of Cx36 at two regulatory sites: Ser110 and Ser293. Our previous work demonstrated that the extent of biotinylated tracer coupling between photoreceptor cells, which provides an index of the extent of electrical coupling, depends on the mouse strain. In the C57Bl/6J strain, light or dopamine reduces tracer coupling and Cx36 phosphorylation in photoreceptors. Conversely, darkness or a dopaminergic antagonist increases tracer coupling and Cx36 phosphorylation, regardless of the daytime. In the CBA/CaJ strain, photoreceptor tracer coupling is not only regulated by light and dopamine, but also by a circadian clock, a type of oscillator with a period close to 24 h and intrinsic to the retina, so that under prolonged dark-adapted conditions tracer coupling is broader at night compared to daytime. In the current study, we examined whether the modulation of photoreceptor coupling by a circadian clock in the CBA/CaJ mouse photoreceptors reflected a change in Cx36 protein expression and/or phosphorylation. We found no significant change in Cx36 expression or in the number of Cx36 gap junction among the conditions examined. However, we found that Cx36 phosphorylation is higher under dark-adapted conditions at night than in the daytime, and is the lowest under prolonged illumination at any time of the day/night cycle. Our observations are consistent with the view that the circadian clock regulation of photoreceptor electrical coupling is mouse strain-dependent and highlights the critical position of Cx36 phosphorylation in the control of photoreceptor coupling.