Brain MRI features and scoring of leukodystrophy in adult-onset Krabbe disease

Objective

To perform a systematic analysis and scoring of brain MRI white matter hyperintensities (WMH) in adult-onset Krabbe disease.

Methods

We retrospectively collected basic clinical data and the first available brain MRI from patients with confirmed Krabbe disease with first clinical manifestations beyond 10 years of age. Data were obtained from our reference center for lysosomal diseases (n = 6) and from contacted authors of published articles describing patients with adult-onset Krabbe disease (n = 15). T2-weighted fluid-attenuated inversion recovery images of each patient were analyzed and scored using a radiologic score of WMH in a single center.

Results

The corticospinal tract was always affected by WMH (100% of patients), however, with some distinctions along the tract: the precentral gyrus (100%), corona radiata (95%), and posterior internal capsule (81%) were highly abnormal, whereas the mesencephalon (57%), pons (52%), and medulla oblongata (5%) were less affected. WMH were also frequently present in the posterior lateral periventricular white matter (95%), optic radiations (86%), postcentral gyrus (71%), medial lemniscus (62%), and corpus callosum, especially in the isthmus (71%), whereas the genu was always normal. A few patients did not have the classical MRI pattern but extensive hyperintensities (n = 3), or patchy distribution of hyperintensities mimicking an acquired etiology (n = 2), or very subtle hyperintensities of the corticospinal tract (n = 1).

Conclusions

We specified the main locations of WMH, which were observed in the earliest stages of the disease and were also present in patients with atypical MRI pattern, highlighting the importance of radiologic features to guide the diagnosis.

Mobility in survivors with chemotherapy-induced peripheral neuropathy and utility of the 6-min walk test

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a significant and often lasting side effect of cancer treatment, with increasing CIPN severity associated with increasing deficits in balance, gait, and mobility. The 6-min walk test (6MWT) is a widely validated and utilized measure of general physical functioning and mobility, although its utility in a CIPN context is unclear. This study aimed to determine the utility of the 6MWT as an assessment of mobility deficits in a CIPN cohort and utilize the 6MWT to compare mobility data from CIPN patients to those of healthy and clinical populations.

METHODS

Cancer survivors exposed to neurotoxic chemotherapies (N = 100; mean 17 ± 13 months post-treatment; mean age 59 ± 13 years) completed a single cross-sectional assessment of patient-reported and objective CIPN, mobility (6MWT), and disability.

RESULTS

CIPN symptoms were reported in the majority of the cohort (87%). Increasing age, patient-reported and objective CIPN symptoms, and disability were associated with decreasing 6MWT distance (.48 ≤ R ≤ .63; p < .001) in bivariate models. Multiple regression models of 6MWT distance included age, sex, and patient-reported or objective CIPN severity as significant independent correlates (.62 ≤ R ≤ .64; p < .03). 6MWT distances in patients with CIPN symptom severity above the cohort mean were consistent with mean values reported in diabetic neuropathy and clinical populations.

CONCLUSIONS

Increased CIPN symptoms are associated with increased mobility deficits. The 6MWT demonstrates promising utility as a mobility assessment in a CIPN cohort.

IMPLICATIONS FOR CANCER SURVIVORS

The impact of the progression of CIPN on mobility deficits in survivors emphasizes the need for effective interventions to treat and prevent CIPN.

Bi-allelic Loss-of-Function CACNA1B Mutations in Progressive Epilepsy-Dyskinesia

The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Ca_v2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca²⁺ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Ca_v2.2 in normal human neurodevelopment.

Half a century of continuous pacing: a living witness to the evolution of a technology

To chart the development of pacing technology and its pitfalls we present the experience of a patient who has benefitted from it but also suffered as a result of it from its earliest days. A 53-year-old physician was referred to us with obstruction of the superior and inferior vena cava on a background of more than 50 years of continuous ventricular pacing and 24 previous pacemaker-related interventions. In a single surgical procedure, his existing pacing system and redundant leads were extracted, the superior vena cava was reconstructed, and a new biventricular pacing system with epicardial leads was implanted. Pacemakers can maintain life and preserve the quality of life for many decades. The quality of this therapy has improved due to advances in the technology and in techniques. Maintaining safe pacing in the very long term requires labour, patience, and ingenuity.

Preequilibrium Asymmetries in the ^{239}Pu(n,f) Prompt Fission Neutron Spectrum

The physical properties of neutrons emitted from neutron-induced fission are fundamental to our understanding of nuclear fission. However, while state-of-the-art fission models still incorporate isotropic fission neutron spectra, it is believed that the preequilibrium prefission component of these spectra is strongly anisotropic. The lack of experimental guidance on this feature has not motivated incorporation of anisotropic neutron spectra in fission models, though any significant anisotropy would impact descriptions of a fissioning system. In the present work, an excess of counts at high energies in the fission neutron spectrum of ^{239}Pu is clearly observed and identified as an excess of the preequilibrium prefission distribution above the postfission neutron spectrum. This excess is separated from the underlying postfission neutron spectrum, and its angular distribution is determined as a function in incident neutron energy and outgoing neutron detection angle. Comparison with neutron scattering models provides the first experimental evidence that the preequilibrium angular distribution is uncorrelated with the fission axis. The results presented here also impact the interpretation of several influential prompt fission neutron spectrum measurements.

Temporal Encoding to Reject Background Signals in a Low Complexity, Photon Counting Communication Link

Communicating information at the few photon level typically requires some complexity in the transmitter or receiver in order to operate in the presence of noise. This in turn incurs expense in the necessary spatial volume and power consumption of the system. In this work, we present a self-synchronised free-space optical communications system based on simple, compact and low power consumption semiconductor devices. A temporal encoding method, implemented using a gallium nitride micro-LED source and a silicon single photon avalanche photo-detector (SPAD), demonstrates data transmission at rates up to 100 kb/s for 8.25 pW received power, corresponding to 27 photons per bit. Furthermore, the signals can be decoded in the presence of both constant and modulated background noise at levels significantly exceeding the signal power. The system's low power consumption and modest electronics requirements are demonstrated by employing it as a communications channel between two nano-satellite simulator systems.

Neural network identification of people hidden from view with a single-pixel, single-photon detector

Light scattered from multiple surfaces can be used to retrieve information of hidden environments. However, full three-dimensional retrieval of an object hidden from view by a wall has only been achieved with scanning systems and requires intensive computational processing of the retrieved data. Here we use a non-scanning, single-photon single-pixel detector in combination with a deep convolutional artificial neural network: this allows us to locate the position and to also simultaneously provide the actual identity of a hidden person, chosen from a database of people (N = 3). Artificial neural networks applied to specific computational imaging problems can therefore enable novel imaging capabilities with hugely simplified hardware and processing times.

Comprehensive Cancer-Predisposition Gene Testing in an Adult Multiple Primary Tumor Series Shows a Broad Range of Deleterious Variants and Atypical Tumor Phenotypes

Multiple primary tumors (MPTs) affect a substantial proportion of cancer survivors and can result from various causes, including inherited predisposition. Currently, germline genetic testing of MPT-affected individuals for variants in cancer-predisposition genes (CPGs) is mostly targeted by tumor type. We ascertained pre-assessed MPT individuals (with at least two primary tumors by age 60 years or at least three by 70 years) from genetics centers and performed whole-genome sequencing (WGS) on 460 individuals from 440 families. Despite previous negative genetic assessment and molecular investigations, pathogenic variants in moderate- and high-risk CPGs were detected in 67/440 (15.2%) probands. WGS detected variants that would not be (or were not) detected by targeted resequencing strategies, including low-frequency structural variants (6/440 [1.4%] probands). In most individuals with a germline variant assessed as pathogenic or likely pathogenic (P/LP), at least one of their tumor types was characteristic of variants in the relevant CPG. However, in 29 probands (42.2% of those with a P/LP variant), the tumor phenotype appeared discordant. The frequency of individuals with truncating or splice-site CPG variants and at least one discordant tumor type was significantly higher than in a control population (χ2 = 43.642; p ≤ 0.0001). 2/67 (3%) probands with P/LP variants had evidence of multiple inherited neoplasia allele syndrome (MINAS) with deleterious variants in two CPGs. Together with variant detection rates from a previous series of similarly ascertained MPT-affected individuals, the present results suggest that first-line comprehensive CPG analysis in an MPT cohort referred to clinical genetics services would detect a deleterious variant in about a third of individuals.

A Note on Testing for Intervention Effects on Binary Responses

Objectives: In some circumstances controlled trials are not feasible and treatments can only be evaluated using clinical databases. Here we consider the situation where treatment is introduced at a particular calendar time and can only be evaluated by comparison with historical controls. In these circumstances Heuer and Abel recommended using change-point methods to search for change in characteristics over the whole study period rather than simply comparing treated and untreated patients. Their recommendation is to only conclude that the intervention had an effect if a change-point could be demonstrated close in time to the introduction of the new treatment. This reduces the risk of false positives caused by confounding changes in population characteristics or changes in patient management. For binary data we develop a method that follows their philosophy and apply it to an observational study in the treatment of pin sites after orthopaedic surgery.

Methods: Tests for change in binomial probabilities based on Brownian bridge and Hansen’s approximation for maximally selected X 2 statistics are compared to an exact test by Worsley. The approximate method is generalized to logistic regression models allowing for covariates.

Results: The agreement of the exact and approximate method is good for sample sizes of 100 or more. The actual test size of the Hansen approximate test allowing for covariates is close to the nominal level, whereas the Brownian bridge approximation is slightly conservative. The change in pin site treatment significantly reduces the risk of infection for both adults and children.

Conclusions: We consider the Hansen approximation to provide a very good and very simple method for obtaining the p-value when testing for a change in binary data event probabilities, with or without covariates.

Accredited accommodation: an alternative to in-patient care in rural north Powys

Various alternatives to psychiatric in-patient care have recently been reviewed (Boardman & Hodgson, 2000). The Accredited Accommodation Scheme in north Powys represents a novel, local alternative to in-patient care, for a targeted group of patients with enduring forms of mental illness.

The Australian Mid-West Coastal Marine Wound Infections Study

BACKGROUND

Marine organism wound infections are common in coastal regions of Western Australia. Local treatment guidelines are based on studies from elsewhere. The objective of this article was to identify the causative organisms in marine wounds sustained in the subtropical and tropical coastal waters of the Indian Ocean, Gascoyne region (north-west), Western Australia.

METHODS

This was a prospective study. A single wound swab was taken from 28 consenting patients who presented with a suppurating marine wound to the emergency departments of Carnarvon and Exmouth hospitals.

RESULTS

The wounds of 27 out of 28 patients returned a positive culture. The two most common organisms were Staphylococcus aureus (n = 18/28; 64.3%) and Vibrio species (n = 9/28; 32.1%). The culture was polymicrobial in 11 patients (39.3%).

DISCUSSION

S. aureus or Vibrio species were frequently seen in marine wounds, and infections were often polymicrobial. Our results suggest that flucloxacillin (or clindamycin) and doxycycline (or ciprofloxacin) would be a reasonable combination for empirical oral therapy in adults.