Formation of Nuclear-Polarized Phases of H Atoms Embedded in Solid H_{2} Films.

We report on an experimental observation of two phases of hydrogen atoms in solid H_{2} films at temperatures of 0.1-0.8 K, characterized by a large enhancement of the nuclear spin polarization compared to that given by Boltzmann statistics (p=0.15 at T=0.15 K). The first phase with p=0.35(5) is formed spontaneously during sample storage in a high magnetic field (B=4.6 T). The second phase with an even higher nuclear polarization, p=0.75(7), can be achieved at T≤0.55 K by repeating sequences of dynamic nuclear polarization followed by a system relaxation. Upon warming through the range 0.55-0.65 K, the highly nuclear-polarized phase undergoes a phase transition to the spontaneously polarized phase which breaks down at T≃0.8 K, and the nuclear polarization gradually converges to the Boltzmann distribution. We discuss possible scenarios for explaining the nature of the observed phenomena.

Huntington's disease: a clinical review.

Huntington's disease (HD) is a fully penetrant neurodegenerative disease caused by a dominantly inherited CAG trinucleotide repeat expansion in the huntingtin gene on chromosome 4. In Western populations HD has a prevalence of 10.6-13.7 individuals per 100 000. It is characterized by cognitive, motor and psychiatric disturbance. At the cellular level mutant huntingtin results in neuronal dysfunction and death through a number of mechanisms, including disruption of proteostasis, transcription and mitochondrial function and direct toxicity of the mutant protein. Early macroscopic changes are seen in the striatum with involvement of the cortex as the disease progresses. There are currently no disease modifying treatments; therefore supportive and symptomatic management is the mainstay of treatment. In recent years there have been significant advances in understanding both the cellular pathology and the macroscopic structural brain changes that occur as the disease progresses. In the last decade there has been a large growth in potential therapeutic targets and clinical trials. Perhaps the most promising of these are the emerging therapies aimed at lowering levels of mutant huntingtin. Antisense oligonucleotide therapy is one such approach with clinical trials currently under way. This may bring us one step closer to treating and potentially preventing this devastating condition.

Spectroscopic observation of nitrogen anions N(-) in solid matrices.

Analysis of old and recent experiments on thermoluminescence of cryocrystals and nanoclusters of N2, Ne, Ar, and Kr containing stabilized nitrogen atoms, suggests that the so-called γ-line may correspond to the bound-bound transition (1)D-(3)P of nitrogen anions N(-) formed in solids by the association of delocalized electrons and metastable nitrogen atoms N((2)D). The recent observations of the γ-line were accompanied by simultaneous luminescence of metastable nitrogen N((2)D) atoms and exoelectron emission. The fine structure of the γ-line at 793 nm has been experimentally observed and investigated for the first time.

Oculoleptomeningeal Amyloidosis associated with transthyretin Leu12Pro in an African patient.

Oculoleptomeningeal amyloidosis is a rare manifestation of hereditary transthyretin (TTR) amyloidosis. Here, we present the first case of leptomeningeal amyloidosis associated with the TTR variant Leu12Pro mutation in an African patient. A 43-year-old right-handed Nigerian man was referred to our centre with rapidly progressive neurological decline. He presented initially with weight loss, confusion, fatigue, and urinary and erectile dysfunction. He then suffered recurrent episodes of slurred speech with right-sided weakness. He went on to develop hearing difficulties and painless paraesthesia. Neurological examination revealed horizontal gaze-evoked nystagmus, brisk jaw jerk, increased tone, brisk reflexes throughout and bilateral heel-shin ataxia. Magnetic resonance imaging showed extensive leptomeningeal enhancement. Cerebrospinal fluid analysis showed a raised protein of 6.4 g/dl. Nerve conduction studies showed an axonal neuropathy. Echocardiography was characteristic of cardiac amyloid. TTR gene sequencing showed that he was heterozygous for the leucine 12 proline mutation. Meningeal and brain biopsy confirmed widespread amyloid angiopathy. TTR amyloidosis is a rare cause of leptomeningeal enhancement, but should be considered if there is evidence of peripheral or autonomic neuropathy with cardiac or ocular involvement. The relationship between different TTR mutations and clinical phenotype, disease course, and response to treatment remains unclear.

Experimental setup for investigation of nanoclusters at cryogenic temperatures by electron spin resonance and optical spectroscopies.

We present the design and performance of an experimental setup for simultaneous electron spin resonance (ESR) and optical studies of nanoclusters with stabilized free radicals at cryogenic temperatures. A gas mixture of impurities and helium after passing through a RF discharge for dissociation of molecules is directed onto the surface of superfluid helium to form the nanoclusters of impurities. A specially designed ESR cavity operated in the TE011 mode allows optical access to the sample. The cavity is incorporated into a homemade insert which is placed inside a variable temperature insert of a Janis (4)He cryostat. The temperature range for sample investigation is 1.25-300 K. A Bruker EPR 300E and Andor 500i optical spectrograph incorporated with a Newton EMCCD camera are used for ESR and optical registration, respectively. The current experimental system makes it possible to study the ESR and optical spectra of impurity-helium condensates simultaneously. The setup allows a broad range of research at low temperatures including optically detected magnetic resonance, studies of chemical processes of the active species produced by photolysis in solid matrices, and investigations of nanoclusters produced by laser ablation in superfluid helium.

Luminescence of oxygen atoms stimulated by metastable helium at cryogenic temperatures.

We present investigations of the afterglow of oxygen-helium gas mixtures at cryogenic temperatures. The cooling of a helium jet containing trace amounts of oxygen after passing through a radio frequency discharge zone led to the observation of strong emissions from atomic oxygen. The effect results from the increasing efficiency of energy transfer from metastable helium atoms and molecules to oxygen impurities in the cold dense helium vapor. This effect might find an application for the detection of small quantities of the impurities in helium gas.

Educational interventions in neurology: a comprehensive systematic review.

A fear of neurology and neural sciences (neurophobia) may have clinical consequences. There is therefore a need to formulate an evidence-based approach to neurology education. A comprehensive systematic review of educational interventions in neurology was performed. BEI, Cochrane Library, Dialog Datastar, EBSCO Biomedical, EBSCO Psychology & Behavioral Sciences, EMBASE, ERIC, First Search, MDConsult, Medline, Proquest Medical Library and Web of Knowledge databases were searched for all published studies assessing interventions in neurology education among undergraduate students, junior medical doctors and residents up to and including July 2012. Two independent literature searches were performed for relevant studies, which were then classified for level of evidence using the Centre of Evidence-based Medicine criteria and four levels of Kirkpatrick educational outcomes. One systematic review, 16 randomized controlled trials (RCTs), nine non-randomized cohort/follow-up studies, 33 case series or historically controlled studies and three mechanism-based reasoning studies were identified. Educational interventions showed favourable evaluation or assessment outcomes in 15 of 16 (94%) RCTs. Very few studies measured subsequent clinical behaviour (two studies) and patient outcomes (one study). There is very little high quality evidence of demonstrably effective neurology education. However, RCTs are emerging, albeit without meeting comprehensive educational criteria. An improving evidence base in the quality of neurology education will be important to reduce neurophobia.

Evaluation of the clinical utility of a carotid bruit.

BACKGROUND: Uncertainty exists over whether listening for carotid bruits as part of the clinical examination is informative in terms of predicting the presence or severity of carotid stenosis. AIM: We sought to undertake a comprehensive meta-analysis and meta-regression of all studies to date that have assessed the relationship between a carotid bruit and severity of degree of stenosis. METHODS: Electronic databases were used to identify all published studies in humans evaluating the association between bruit and stenosis published until and including October 2011. Pooled sensitivity, specificity and diagnostic odds ratio (DOR) were calculated for each stenosis group. Summary receiver operating characteristic (SROC) curve analysis was performed in studies assessing clinically relevant (i.e. >70%) stenosis. Meta-regression was performed in all studies, using random effects. RESULTS: We identified 26 studies evaluating the association between carotid bruit and stenosis, in 15 117 arteries. For clinically relevant stenosis (i.e. >70%), we found pooled sensitivity 0.53 [95% confidence interval (CI): 0.5-0.55], specificity 0.83 (95% CI: 0.82-0.84) and DOR 4.32 (95% CI: 2.78-6.66). SROC curve analysis gave an area under the curve of 0.73. Meta-regression analysis showed a (non-significant) (P = 0.067) inverse relationship between carotid bruit and stenosis. CONCLUSION: The carotid bruit is of moderate value for detecting clinically relevant carotid stenosis. It gives high specificity but low sensitivity. The likelihood of a carotid bruit does not increase at increasing degrees of stenosis.

The value of a liaison neurology service in a district general hospital.

BACKGROUND: Healthcare development in the UK has resulted in an increase in neurologists working in district general hospitals. METHODS: The aim of the study was to determine the use of a neurologist for inpatient diagnosis and management, and to measure a neurologist's diagnostic reliability in a district general hospital over a 27-month period. Patient data were prospectively recorded. Follow-up was performed independently by two clinicians reviewing the medical notes. Reasons for diagnostic change were determined. RESULTS: 306 inpatients were referred to the neurologist between 1 January 2007 and 31 March 2009 (2% of medical admissions). Mean (SD) age was 49.3 (18.8) years, and the female/male ratio was 1.2:1. Epilepsy and stroke were the most common diagnoses. Diagnostic concordance between referring physician and neurologist ranged from κ score 0.13 (spinal pathology) to 0.83 (central nervous system infection). Neurological opinion resulted in diagnostic change in 38.2% and management change in 88.8%. Only 1.6% of patients remained without a diagnosis, a fourfold improvement from physician referral. After medical records had been reviewed, 3.3% of inpatient diagnoses (10 of 306 patients) changed from the original diagnosis by the neurologist. Specialist investigation helped in revising diagnoses in four of the 10 diagnostic changes. CONCLUSION: This study shows that in a district general hospital a neurologist can contribute to inpatient diagnosis and management with minimal diagnostic change over time, suggesting reliability of this service.