Elevated Levels of Homocysteinesulfinic Acid in the Plasma of Patients with Amyotrophic Lateral Sclerosis: A Potential Source of Excitotoxicity?

OBJECTIVES

Excitotoxicity is thought to be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). One possible source of excitotoxicity is the presence of sulphur amino acids (SAAs). In the brain of subjects with ALS, there are increased levels of taurine. In the metabolism of methionine to taurine, excitatory sulphur amino acids (SAAs) are formed. These could potentially contribute to excitotoxicity in ALS. The present study has examined whether plasma levels of SAAs in 38 ALS patients differ from those of 30 healthy controls.

METHODS

Plasma levels of SAAs were measured by liquid chromatography mass spectrometry.

RESULTS

There were no significant changes in plasma cysteic acid, cysteine sulfinic acid, and homocysteic acid in ALS patients compared to healthy subjects. Significant elevations in plasma homocysteinesulfinic acid (HCSA) levels (p < 0.0001) were observed in the ALS patients (75.91 ± 15.38 nM) compared to healthy controls (54.06 ± 8.503 nM); 50% of the ALS patients had HCSA levels that were 1.5-2-folds higher than those of controls. Plasma levels of HCSA differed significantly (p = 0.0440) between patients with bulbar onset and spinal onset (68.57 ± 14.20 vs. 79.30 ± 14.95 nM, respectively).

CONCLUSION

HCSA is elevated in the blood of subjects with ALS. Since HCSA can be transported from the blood to the CNS by active transport, has neurotransmitter properties, and can activate synaptic receptors including NMDAR and metabotropic glutamate receptor, it is possible that increases in HCSA could influence glutamatergic neurotransmission and potentially contribute to excitotoxicity in some ALS patients.

Subcutaneous administration of benzathine benzylpenicillin G has favourable pharmacokinetic characteristics for the prevention of rheumatic heart disease compared with intramuscular injection: a randomized, crossover, population pharmacokinetic study in healthy adult volunteers

BACKGROUND

Benzathine penicillin G has been used as monthly deep intramuscular (IM) injections since the 1950s for secondary prevention of acute rheumatic fever and rheumatic heart disease (RHD). Injection frequency and pain are major programmatic barriers for adherence, prompting calls for development of better long-acting penicillin preparations to prevent RHD. We hypothesized that subcutaneous (SC) administration of benzathine penicillin G could delay penicillin absorption when compared with IM injections.

METHODS

To compare the pharmacokinetic profile and tolerability of benzathine penicillin G according to different routes of administration, 15 healthy males participated in a randomized crossover study to receive benzathine penicillin G by either SC or IM routes, with a 10 week washout period before the second dose by the alternative route. Ultrasound guidance confirmed injection location. Penicillin concentrations and pain scores were measured for 6 weeks following injections.

RESULTS

SC administration was well tolerated with no significant differences in pain scores. Following SC injection, the principal absorption half-life (95% CI) was 20.1 (16.3-29.5) days and 89.6% (87.1%-92.0%) of the drug was directed via this pathway compared with 10.2 (8.6-12.5) days and 71.3% (64.9%-77.4%) following IM administration. Lower peak and higher trough penicillin concentrations resulted following SC injection. Simulations demonstrated that SC infusion of higher doses of benzathine penicillin G could provide therapeutic penicillin concentrations for 3 months.

CONCLUSIONS

SC administration of benzathine penicillin G is safe and significantly delays penicillin absorption. High-dose benzathine penicillin G via the SC route would fulfil many product characteristics required for the next generation of longer-acting penicillins for use in RHD.

Left atrial appendage occlusion in the UK: prospective registry and data linkage to Hospital Episode Statistics

AIMS

Non-valvular atrial fibrillation (AF) greatly increases the risk of ischaemic stroke. For people with contraindications to oral anticoagulation, left atrial appendage occlusion (LAAO) provides a non-pharmacological management alternative. The aim of this study was to measure the procedural safety and longer-term effectiveness of LAAO for AF in a UK setting.

METHODS AND RESULTS

This was a prospective, single-armed registry of patients with AF for whom anticoagulation was unsuitable. Registry data were collected between October 2014 and April 2018 and linked to routine data sources for Follow-up.Data from 583 LAAO procedures were entered into the registry, of which 537 (from 525 patients) were eligible for inclusion (median CHA2DS2-VASc score 4). A closure device was successfully implanted in 93.4% of cases, with a procedural success rate (device implanted without major complication) of 88.9%. Five patients (1.0%) died in hospital. During follow-up (median 729 (Q1: Q3, 523:913) days) 45 patients experienced neurological events; 33 of which were ischaemic. The ischaemic neurological event rate was 3.3 [1.6 to 5.0]% at 1 year (n = 387) and 7.0 [4.3 to 9.6]% at 2-years (n = 196). There were significant improvements in overall patient health (via Visual Analogue Scale) measured at 6 weeks and 6 months, but no significant improvements observed in patient utility over time.

CONCLUSION

The findings of our study suggest that LAAO is not without procedural risk, but that this risk may be justified in high-risk patients with AF who cannot take an anticoagulant. Moreover the data do not provide support for more widespread use of LAAO as the complication rate was relatively high and would be would be difficult to justify in many patients with AF who tolerate anticoagulation.

Towards combined quantum bit detection and spatial tracking using an arrayed single-photon sensor

Experimental quantum key distribution through free-space channels requires accurate pointing-and-tracking to co-align telescopes for efficient transmission. The hardware requirements for the sender and receiver could be drastically reduced by combining the detection of quantum bits and spatial tracking signal using two-dimensional single-photon detector arrays. Here, we apply a two-dimensional CMOS single-photon avalanche diode detector array to measure and monitor the single-photon level interference of a free-space time-bin receiver interferometer while simultaneously tracking the spatial position of the single-photon level signal. We verify an angular field-of-view of 1.28° and demonstrate a post-processing technique to reduce background noise. The experimental results show a promising future for two-dimensional single-photon detectors in low-light level free-space communications, such as quantum communications.

Cyclophosphamide alters the tumor cell secretome to potentiate the anti-myeloma activity of daratumumab through augmentation of macrophage-mediated antibody dependent cellular phagocytosis

Multiple Myeloma (MM) is a malignant disorder of plasma cells which, despite significant advances in treatment, remains incurable. Daratumumab, the first CD38 directed monoclonal antibody, has shown promising activity alone and in combination with other agents for MM treatment. Daratumumab is thought to have pleiotropic mechanisms of activity including natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC). With the knowledge that CD38-expressing NK cells are depleted by daratumumab, we sought to investigate a potential mechanism of enhancing macrophage-mediated antibody-dependent cellular phagocytosis (ADCP) by combining daratumumab with cyclophosphamide (CTX). Cyclophosphamide’s immunomodulatory function was investigated by conditioning macrophages with tumor cell secretome collected from cyclophosphamide treated MM cell lines (CTX-TCS). Flow cytometry analysis revealed that CTX-TCS conditioning augmented the migratory capacity of macrophages and increased CD32 and CD64 Fcγ receptor expression on their cell surface. Daratumumab-specific tumor clearance was increased by conditioning macrophages with CTX-TCS in a dose-dependent manner. This effect was impeded by pre-incubating macrophages with Cytochalasin D (CytoD), an inhibitor of actin polymerization, indicating macrophage-mediated ADCP as the mechanism of clearance. CD64 expression on macrophages directly correlated with MM cell clearance and was essential to the observed synergy between cyclophosphamide and daratumumab, as tumor clearance was attenuated in the presence of a FcγRI/CD64 blocking agent.

Cyclophosphamide independently enhances daratumumab-mediated killing of MM cells by altering the tumor microenvironment to promote macrophage recruitment, polarization to a pro-inflammatory phenotype, and directing ADCP. These findings support the addition of cyclophosphamide to existing or novel monoclonal antibody-containing MM regimens.

Association of mild cognitive impairment and characteristic of COPD and overall health status in a cohort study

Introduction: We evaluated risk factors and demographic characteristics of associated with mild cognitive impairment (MCI) in patients with COPD. Methods: 220 individuals with COPD enrolled in a cohort study designed to evaluate anxiety conducted at 16 clinical centers. Cognitive impairment was assessed with the Montreal Cognitive Assessment (MoCA), a cutoff score of <26 defined as MCI. Data were collected including spirometry, 6-minute walk test, symptom burden by COPD Assessment Test and dyspnea by Modified Medical Research Council, anxiety measured by Anxiety Inventory of Respiratory Disease, Generalized Anxiety Disorder-7 and Hospital Anxiety Depression Scale, depression by Patient Health Questionnaire-9 and health status by Patient Reported Outcomes Measurement Information System and sleep quality by the Pittsburg Sleep Quality Index. Results: The median age was 65 years and 54% of participants were male. 119(54%) of participants had MCI as classified by MoCA. In multivariable logistic regression, higher odds ratios (OR) (95% confidence interval) for MCI (MoCA) <26 were associated with increased years of age, 1.06 (1.02 -1-09, p<0.003); African-American race, 3.68(1.67-8.11, p<0.001); persistent phlegm, 2 (1.12-3.57, p<0.01) and sleep disturbance, 1.04(1.01-1.08, p<0.01). Conclusions: COPD patients commonly screen positive for MCI. Characteristics associated with MCI included age, African-American race, sleep disturbance and persistent phlegm.

Event history and topological data analysis

Persistent homology is used to track the appearance and disappearance of features as we move through a nested sequence of topological spaces. Equating the nested sequence to a filtration and the appearance and disappearance of features to events, we show that simple event history methods can be used for the analysis of topological data. We propose a version of the well-known Nelson–Aalen cumulative hazard estimator for the comparison of topological features of random fields and for testing parametric assumptions. We suggest a Cox proportional hazards approach for the analysis of embedded metric trees. The Nelson–Aalen method is illustrated on globally distributed climate data and on neutral hydrogen distribution in the Milky Way. The Cox method is used to compare vascular patterns in fundus images of the eyes of healthy and diabetic retinopathy patients.

New onset left bundle branch block after transcatheter aortic valve implantation and the effect on long-term survival – a UK wide experience

Introduction

New onset left bundle branch block (LBBB) is the most common conduction disturbance associated with transcatheter aortic valve implantation (TAVI). It has been shown to adversely affect cardiac function and increase re-hospitalisation, although its impact on mortality remains contentious.

Methods

We conducted an observational cohort analysis of all TAVI procedures performed by 13 heart teams in the United Kingdom from inception of their structural programmes until 31st July 2013. The primary outcome was 1-year all-cause mortality. Secondary outcomes included left ventricular ejection fraction (LVEF) at 30 days and need for a post-TAVI permanent pacemaker (PPM).

Results

1785 patients were eligible for inclusion to the study. The primary analysis cohort was composed of 1409 patients with complete electrocardiographic (ECG) data pre- and post-TAVI. Pre-existing LBBB was present in 200 (14.2%) patients. New LBBB occurred in 323 (22.9%) patients post TAVI, which resolved in 99 (7%) patients prior to discharge. A balloon-expandable device was implanted in 968 (69%) patients, whilst 421 (30%) patients received a self-expandable valve. New LBBB was observed in 120 (12.4%) and 192 (45.6%) patients receiving a balloon- or self-expandable prosthesis respectively.

Overall 1-year all-cause mortality post TAVI was 18.7%. New onset LBBB was not associated with an increase in 1-year all-cause mortality (p=0.416). Factors that were associated with mortality included an increasing logistic EuroScore (p=0.05), history of previous balloon aortic valvuloplasty (p=0.001), renal impairment (p=0.003), previous myocardial infarction with pre-existing LBBB (p=0.028) and atrial fibrillation (p=0.039). Lower baseline peak and mean AV gradients were also associated with greater mortality at 1 year (p=0.001), likely reflecting underlying left ventricular dysfunction.

In the majority of patients, LVEF remained unchanged following TAVI. Interestingly, the presence or absence of new onset LBBB did not affect LVEF improvement at 30 days. 10% of patients required a PPM post TAVI. Predictors of PPM included new LBBB (OR 2.6, p&lt;0.001), pre-TAVI left ventricular systolic impairment (OR 1.2, p=0.037), a self-expandable device (p&lt;0.001), and pre-existing RBBB (OR 4.0, p&lt;0.001).

Conclusions

These findings suggest that new onset LBBB post TAVI does not increase mortality at 1 year or adversely affect LVEF at 30 days.

Funding Acknowledgement

Type of funding source: None

Biclonal lymphoproliferative disorders: another association with NOTCH1-mutated chronic lymphocytic leukaemias

INTRODUCTION

Biclonal lymphoid disorders, when two distinct lymphoproliferative disorders (LPD) co-exist, are rare (incidence of 1.4%) and associated with a poor prognosis. NOTCH1 mutations occur in 10% of CLL at diagnosis, associated with a short disease-free interval and increased risk of Richter's transformation. We hypothesised that the incidence of NOTCH1 mutations in CLL with a second LPD may be increased, because the mutation occurs early in leukaemogenesis, permitting clonal divergence.

METHODS

We identified 19 patients with biclonal LPD at diagnosis: 11 with CLL and a second LPD (group A) and 8 with a second distinct CLL (group B). NOTCH1 mutation analysis was performed and clinical outcome investigated.

RESULTS

Ten of 19 (52%) were NOTCH1 mutated: 5 in group A (45%) and 5 in group B (62.5%) with a favourable clinical outcome observed among this cohort with 28.7 (range 1-99) months of follow-up.

CONCLUSION

In conclusion, we identified a significant (52%) incidence of NOTCH1 mutations in CLL in the context of biclonal LPD, associated with an indolent clinical course.

Elevated plasma levels of D-serine in some patients with amyotrophic lateral sclerosis

D-serine is an endogenous co-agonist with glutamate for activation of the N-methyl-D-aspartate receptor (NMDAR). D-serine exacerbates neuronal death and is elevated in the spinal cord from patients with sporadic/familial ALS. The present study was undertaken to examine whether plasma levels of D-serine of patients with ALS are different from those of healthy controls. Levels of D-serine in plasma (30 patients and 30 controls) were measured by high-performance liquid chromatography mass spectrometry. Plasma levels of D-serine in ALS patients (mean 39.27 ± 28.61 ng/ml) were significantly higher (p = 0.0293) than those of healthy control subjects (mean 21.07 ± 14.03 ng/ml) as well as previously reported values for healthy controls; ∼43% of patients had plasma D-serine levels that were 2 to 4-folds higher than those of controls. There was no association of plasma D-serine levels with disability, the duration of disease or with the age of subjects. In conclusion, we show that D-serine levels are elevated in the plasma of some ALS patients. Since D-serine serves as a co-agonist/activator of NMDAR, increases in D-serine could have a direct influence on glutamatergic neurotransmission and potentially contribute to excitotoxicity in some ALS patients.

Genome-wide Meta-analysis Finds the ACSL5-ZDHHC6 Locus Is Associated with ALS and Links Weight Loss to the Disease Genetics

We meta-analyze amyotrophic lateral sclerosis (ALS) genome-wide association study (GWAS) data of European and Chinese populations (84,694 individuals). We find an additional significant association between rs58854276 spanning ACSL5-ZDHHC6 with ALS (p = 8.3 × 10⁻⁹), with replication in an independent Australian cohort (1,502 individuals; p = 0.037). Moreover, B4GALNT1, G2E3-SCFD1, and TRIP11-ATXN3 are identified using a gene-based analysis. ACSL5 has been associated with rapid weight loss, as has another ALS-associated gene, GPX3. Weight loss is frequent in ALS patients and is associated with shorter survival. We investigate the effect of the ACSL5 and GPX3 single-nucleotide polymorphisms (SNPs), using longitudinal body composition and weight data of 77 patients and 77 controls. In patients’ fat-free mass, although not significant, we observe an effect in the expected direction (rs58854276: −2.1 ± 1.3 kg/A allele, p = 0.053; rs3828599: −1.0 ± 1.3 kg/A allele, p = 0.22). No effect was observed in controls. Our findings support the increasing interest in lipid metabolism in ALS and link the disease genetics to weight loss in patients.

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Cross-ethnic meta-analysis finds an association between the ACSL5-ZDHHC6 locus and ALS

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The ACSL5-ZDHHC6 association is replicated in an independent Australian cohort

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ACSL5-ZDHHC6 lead SNP is in ACSL5 and is an eQTL of ZDHHC6 in brain tissues

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ACSL5 SNPs might have an effect on fat-free mass in ALS patients

Adaptive treatment and robust control

A control theory perspective on determination of optimal dynamic treatment regimes is considered. The aim is to adapt statistical methodology that has been developed for medical or other biostatistical applications to incorporate powerful control techniques that have been designed for engineering or other technological problems. Data tend to be sparse and noisy in the biostatistical area and interest has tended to be in statistical inference for treatment effects. In engineering fields, experimental data can be more easily obtained and reproduced and interest is more often in performance and stability of proposed controllers rather than modeling and inference per se. We propose that modeling and estimation should be based on standard statistical techniques but subsequent treatment policy should be obtained from robust control. To bring focus, we concentrate on A-learning methodology as developed in the biostatistical literature and H ∞ -synthesis from control theory. Simulations and two applications demonstrate robustness of the H ∞ strategy compared to standard A-learning in the presence of model misspecification or measurement error.

Is it Pompe Disease? Australian diagnostic considerations

Pompe Disease is a spectrum disorder with an evolving phenotype in which diagnostic delay is common. Contributing factors include the rarity of the disorder, its wide clinical spectrum, signs and symptoms that overlap with those of other neuromuscular disorders, variable diagnostic approaches, lack of awareness of the clinical manifestations and difficulties in completing the diagnostic inventory. International updates and recommendations have been published providing diagnostic guidelines and management criteria. However, questions remain in the Australian setting. A panel (two neurologists, one clinical geneticist) reviewed the literature, examined clinical questions of relevance to the Australian setting, and developed a framework for the guidance. A wider panel, comprising the initial panel plus eight additional members, critiqued the framework and contributed clinical guidance within the scope of their respective areas of clinical expertise. The resultant expert consensus recommendations build on currently available data to propose an appropriate management framework incorporating the diagnosis, classification, therapeutic approach, multidisciplinary care, and on-going monitoring of patients with Pompe Disease in the Australian setting. It is hoped that diagnostic delay can be reduced with appropriate recourse to evidence-based insights and practical advice on diagnosis and management tailored to the Australian setting.

CryoEM at 100 keV: a demonstration and prospects

100 kV is investigated as the operating voltage for single-particle electron cryomicroscopy (cryoEM). Reducing the electron energy from the current standard of 300 or 200 keV offers both cost savings and potentially improved imaging. The latter follows from recent measurements of radiation damage to biological specimens by high-energy electrons, which show that at lower energies there is an increased amount of information available per unit damage. For frozen hydrated specimens around 300 Å in thickness, the predicted optimal electron energy for imaging is 100 keV. Currently available electron cryomicroscopes in the 100-120 keV range are not optimized for cryoEM as they lack both the spatially coherent illumination needed for the high defocus used in cryoEM and imaging detectors optimized for 100 keV electrons. To demonstrate the potential of imaging at 100 kV, the voltage of a standard, commercial 200 kV field-emission gun (FEG) microscope was reduced to 100 kV and a side-entry cryoholder was used. As high-efficiency, large-area cameras are not currently available for 100 keV electrons, a commercial hybrid pixel camera designed for X-ray detection was attached to the camera chamber and was used for low-dose data collection. Using this configuration, five single-particle specimens were imaged: hepatitis B virus capsid, bacterial 70S ribosome, catalase, DNA protection during starvation protein and haemoglobin, ranging in size from 4.5 MDa to 64 kDa with corresponding diameters from 320 to 72 Å. These five data sets were used to reconstruct 3D structures with resolutions between 8.4 and 3.4 Å. Based on this work, the practical advantages and current technological limitations to single-particle cryoEM at 100 keV are considered. These results are also discussed in the context of future microscope development towards the goal of rapid, simple and widely available structure determination of any purified biological specimen.

Three-dimensional imaging of stationary and moving targets in turbid underwater environments using a single-photon detector array

Three-dimensional imaging in underwater environments was investigated using a picosecond resolution silicon single-photon avalanche diode (SPAD) detector array fabricated in complementary metal-oxide semiconductor (CMOS) technology. Each detector in the 192  × 128 SPAD array had an individual time-to-digital converter allowing rapid, simultaneous acquisition of data for the entire array using the time-correlated single-photon counting approach. A picosecond pulsed laser diode source operating at a wavelength of 670 nm was used to illuminate the underwater scenes, emitting an average optical power up to 8 mW. Both stationary and moving targets were imaged under a variety of underwater scattering conditions. The acquisition of depth and intensity videos of moving targets was demonstrated in dark laboratory conditions through scattering water, equivalent to having up to 6.7 attenuation lengths between the transceiver and target. Data were analyzed using a pixel-wise approach, as well as an image processing algorithm based on a median filter and polynomial approximation.