Foreground Detection Analysis of Ultrasound Image Sequences Identifies Markers of Motor Neurone Disease across Diagnostically Relevant Skeletal Muscles.

Diagnosis of motor neurone disease (MND) includes detection of small, involuntary muscle excitations, termed fasciculations. There is need to improve diagnosis and monitoring of MND through provision of objective markers of change. Fasciculations are visible in ultrasound image sequences. However, few approaches that objectively measure their occurrence have been proposed; their performance has been evaluated in only a few muscles; and their agreement with the clinical gold standard for fasciculation detection, intramuscular electromyography, has not been tested. We present a new application of adaptive foreground detection using a Gaussian mixture model (GMM), evaluating its accuracy across five skeletal muscles in healthy and MND-affected participants. The GMM provided good to excellent accuracy with the electromyography ground truth (80.17%-92.01%) and was robust to different ultrasound probe orientations. The GMM provides objective measurement of fasciculations in each of the body segments necessary for MND diagnosis and hence could provide a new, clinically relevant disease marker.

Real-Time Ultrasound Segmentation, Analysis and Visualisation of Deep Cervical Muscle Structure.

Despite widespread availability of ultrasound and a need for personalised muscle diagnosis (neck/back pain-injury, work related disorder, myopathies, neuropathies), robust, online segmentation of muscles within complex groups remains unsolved by existing methods. For example, Cervical Dystonia (CD) is a prevalent neurological condition causing painful spasticity in one or multiple muscles in the cervical muscle system. Clinicians currently have no method for targeting/monitoring treatment of deep muscles. Automated methods of muscle segmentation would enable clinicians to study, target, and monitor the deep cervical muscles via ultrasound. We have developed a method for segmenting five bilateral cervical muscles and the spine via ultrasound alone, in real-time. Magnetic Resonance Imaging (MRI) and ultrasound data were collected from 22 participants (age: 29.0±6.6, male: 12). To acquire ultrasound muscle segment labels, a novel multimodal registration method was developed, involving MRI image annotation, and shape registration to MRI-matched ultrasound images, via approximation of the tissue deformation. We then applied polynomial regression to transform our annotations and textures into a mean space, before using shape statistics to generate a texture-to-shape dictionary. For segmentation, test images were compared to dictionary textures giving an initial segmentation, and then we used a customized Active Shape Model to refine the fit. Using ultrasound alone, on unseen participants, our technique currently segments a single image in [Formula: see text] to over 86% accuracy (Jaccard index). We propose this approach is applicable generally to segment, extrapolate and visualise deep muscle structure, and analyse statistical features online.

Blunted angiogenesis and hypertrophy are associated with increased fatigue resistance and unchanged aerobic capacity in old overloaded mouse muscle.

We hypothesize that the attenuated hypertrophic response in old mouse muscle is (1) partly due to a reduced capillarization and angiogenesis, which is (2) accompanied by a reduced oxidative capacity and fatigue resistance in old control and overloaded muscles, that (3) can be rescued by the antioxidant resveratrol. To investigate this, the hypertrophic response, capillarization, oxidative capacity, and fatigue resistance of m. plantaris were compared in 9- and 25-month-old non-treated and 25-month-old resveratrol-treated mice. Overload increased the local capillary-to-fiber ratio less in old (15 %) than in adult (59 %) muscle (P < 0.05). Although muscles of old mice had a higher succinate dehydrogenase (SDH) activity (P < 0.05) and a slower fiber type profile (P < 0.05), the isometric fatigue resistance was similar in 9- and 25-month-old mice. In both age groups, the fatigue resistance was increased to the same extent after overload (P < 0.01), without a significant change in SDH activity, but an increased capillary density (P < 0.05). Attenuated angiogenesis during overload may contribute to the attenuated hypertrophic response in old age. Neither was rescued by resveratrol supplementation. Changes in fatigue resistance with overload and aging were dissociated from changes in SDH activity, but paralleled those in capillarization. This suggests that capillarization plays a more important role in fatigue resistance than oxidative capacity.

Validation of a New Semi-Automated Technique to Evaluate Muscle Capillarization.

The method of capillary domains has often been used to study capillarization of skeletal and heart muscle. However, the conventional data processing method using a digitizing tablet is an arduous and time-consuming task. Here we compare a new semi-automated capillary domain data collection and analysis in muscle tissue with the standard capillary domain method. The capillary density (1481±59 vs. 1447±54 caps mm(-2); R2:0.99; P<0.01) and heterogeneity of capillary spacing (0.085±0.002 vs. 0.085±0.002; R2:0.95; P<0.01) were similar in both methods. The fiber cross-sectional area correlated well between the methods (R2:0.84; P<0.01) and did not differ significantly (~8% larger in the old than new method at P=0.08). The latter was likely due to differences in outlining the contours between the two methods. In conclusion, the semi-automated method gives quantitatively and qualitatively similar data as the conventional method and saves a considerable amount of time.

Ultrasound-Based Detection of Fasciculations in Healthy and Diseased Muscles.

Involuntary muscle activations are diagnostic indicators of neurodegenerative pathologies. Currently detected by invasive intramuscular electromyography, these muscle twitches are found to be visible in ultrasound images. We present an automated computational approach for the detection of muscle twitches, and apply this to two muscles in healthy and motor neuron disease-affected populations. The technique relies on motion tracking within ultrasound sequences, extracting local movement information from muscle. A statistical analysis is applied to classify the movement, either as noise or as more coherent movement indicative of a muscle twitch. The technique is compared to operator identified twitches, which are also assessed to ensure operator agreement. We find that, when two independent operators manually identified twitches, higher interoperator agreement (Cohen's κ) occurs when more twitches are present (κ = 0.94), compared to a lower number (κ = 0.49). Finally, we demonstrate, via analysis of receiver operating characteristics, that our computational technique detects muscle twitches across the entire dataset with a high degree of accuracy (0.83 < accuracy < 0.96).

The role of cholesterol on the activity and stability of neurotensin receptor 1.

Understanding the role of specific bilayer components in controlling the function of G-protein coupled receptors (GPCRs) will be a key factor in the development of novel pharmaceuticals. Cholesterol-dependence in particular has become an area of keen interest with respect to GPCR function; not least since the 2.6Å crystal structure of the ß2 adrenergic receptor revealed a putative cholesterol binding motif conserved throughout class-A GPCRs. Furthermore, experimental evidence for cholesterol-dependent GPCR function has been demonstrated in a limited number of cases. This modulation of receptor function has been attributed to both direct interactions between cholesterol and receptor, and indirect effects caused by the influence of cholesterol on bilayer order and lateral pressure. Despite the widespread occurrence of cholesterol binding motifs, available experimental data on the functional involvement of cholesterol on GPCRs are currently limited to a small number of receptors. Here we investigate the role of cholesterol in the function of the neurotensin receptor 1 (NTS1) a class-A GPCR. Specifically we show how cholesterol, and the analogue cholesteryl hemisuccinate, influence activity, stability, and oligomerisation of both purified and reconstituted NTS1. The results caution against using such motifs as indicators of cholesterol-dependent GPCR activity.

Mutual information for the detection of crush.

Fatal crush conditions occur in crowds with tragic frequency. Event organizers and architects are often criticised for failing to consider the causes and implications of crush, but the reality is that both the prediction and prevention of such conditions offer a significant technical challenge. Full treatment of physical force within crowd simulations is precise but often computationally expensive; the more common method of human interpretation of results is computationally "cheap" but subjective and time-consuming. This paper describes an alternative method for the analysis of crowd behaviour, which uses information theory to measure crowd disorder. We show how this technique may be easily incorporated into an existing simulation framework, and validate it against an historical event. Our results show that this method offers an effective and efficient route towards automatic detection of the onset of crush.

Implementing Health Outcomes for Better Information and Care (HOBIC): Lessons from an Early Adopter Site.

Measuring patient outcomes to assess quality and to support evidence-based decision-making has gained momentum over the last two decades. In Ontario, the Health Outcomes for Better Information and Care (HOBIC) initiative has become a part of the province's Information Management Strategy as a way to demonstrate the impact of nursing care on health outcomes. In fall 2006, HOBIC implementation began in early adopter sites with the goal of sharing lessons learned with other healthcare providers and organizations. This action learning study was undertaken in one of the early adopter sites to gain a greater understanding of the factors that support, or fail to support, the integration of HOBIC into professional practice. Participants reported a lack of confidence using HOBIC that they attributed to scarce resources for ongoing education and support. Together, we developed a simulation workshop aimed at enhancing communication skills to achieve more meaningful nurse-patient interaction during the HOBIC assessment. This paper focuses Canadian nurse leaders' attention on the reality that implementing HOBIC is far from straightforward. The real challenge in HOBIC implementation is not mastery of the technology per se, but support for nurses and their ability to adapt daily practice in order to maximize its functionality.

Constitutive dimerization of the G-protein coupled receptor, neurotensin receptor 1, reconstituted into phospholipid bilayers.

Neurotensin receptor 1 (NTS1), a Family A G-protein coupled receptor (GPCR), was expressed in Escherichia coli as a fusion with the fluorescent proteins eCFP or eYFP. A fluorophore-tagged receptor was used to study the multimerization of NTS1 in detergent solution and in brain polar lipid bilayers, using fluorescence resonance energy transfer (FRET). A detergent-solubilized receptor was unable to form FRET-competent complexes at concentrations of up to 200 nM, suggesting that the receptor is monomeric in this environment. When reconstituted into a model membrane system at low receptor density, the observed FRET was independent of agonist binding, suggesting constitutive multimer formation. In competition studies, decreased FRET in the presence of untagged NTS1 excludes the possibility of fluorescent protein-induced interactions. A simulation of the experimental data indicates that NTS1 exists predominantly as a homodimer, rather than as higher-order multimers. These observations suggest that, in common with several other Family A GPCRs, NTS1 forms a constitutive dimer in lipid bilayers, stabilized through receptor-receptor interactions in the absence of other cellular signaling components. Therefore, this work demonstrates that well-characterized model membrane systems are useful tools for the study of GPCR multimerization, allowing fine control over system composition and complexity, provided that rigorous control experiments are performed.

Improved yield of a ligand-binding GPCR expressed in E. coli for structural studies.

The G-protein coupled receptor (GPCR), rat brain neurotensin receptor type I (NTS1) is one of a small number of GPCRs that have been successfully expressed in Escherichia coli as a functional, ligand-binding receptor, but yields of purified receptor are still low for comprehensive structural studies. Here, several approaches have been examined to optimize the yields of active, ligand-binding receptor. Optimisation of E. coli strain and induction protocol yielded a significant improvement in expression of active receptor. Expression of the receptor in BL21(DE3) cells, in combination with autoinduction improved expression 10-fold when compared with previously reported expression protocols using IPTG-mediated induction in DH5alpha cells. Optimization of the purification protocol revealed that supplementation of buffers with phospholipids enhanced recovery of active receptor. The methods examined are potentially applicable to other GPCRs expressed in E. coli.

Functional electrical stimulation (FES) of the upper limb alleviates unilateral neglect: a case series analysis.

We report the results of a new form of therapy for unilateral spatial neglect. Functional electrical stimulation (FES) applied to the left forearm extensor muscles reduced the symptoms of severe left unilateral visual neglect in three patients, with the benefits being measurable at 6 months post-treatment. We suggest that FES activates a proprioceptive map within the right parietal lobe whose level of activation is otherwise diminished by the lesion. This both increases awareness of the contralesional side and stimulates functional interactions with the environment.

Multiple oxidative phosphorylation deficiencies in severe childhood multi-system disorders due to polymerase gamma (POLG1) mutations.

Failure to thrive, feeding difficulties, variable forms of infantile epilepsy or psychomotor developmental delay and hypotonia were the most frequent clinical disease presentations in eight children with combined oxidative phosphorylation enzyme complex deficiencies carrying mutations in the polymerase gamma (POLG1) gene. Five out of eight patients developed severe liver dysfunction during the course of the disease. Three of these patients fulfilled the disease criteria for Alpers syndrome. Most children showed deficiencies of respiratory chain enzyme complexes I and III, in combination with complex II, complex IV and/or PDHc in muscle, whereas in fibroblasts normal enzyme activities were measured. All children carried homozygous or compound heterozygous mutations in the POLG1 gene, including two novel mutations in association with mtDNA depletion. Conclusion We suggest performing POLG1 mutation analysis in children with combined oxidative phosphorylation deficiencies in muscle, even if the clinical picture is not Alpers syndrome.

Direct analysis of a GPCR-agonist interaction by surface plasmon resonance.

Despite their clinical importance, detailed analysis of ligand binding at G-protein coupled receptors (GPCRs) has proved difficult. Here we successfully measure the binding of a GPCR, neurotensin receptor-1 (NTS-1), to its ligand, neurotensin (NT), using surface plasmon resonance (SPR). Specific responses were observed between NT and purified, detergent-solublised, recombinant NTS-1, using a novel configuration where the biotinylated NT ligand was immobilised on the biosensor surface. This SPR approach shows promise as a generic approach for the study of ligand interactions with other suitable GPCRs.

Is heart rate variability an objective parameter with which to manage treatment of infants with heart failure due to left-to-right shunting?

Treatment in heart failure could be guided by additional non-clinical measures, such as neurohumoral levels. Variability in heart rate is known to reflect neurohumoral stimulation. With this in mind, we sought to assess retrospectively the variability in heart rate to guide the treatment of infants in heart failure. We analysed retrospectively the data from 20 infants with a significant left-to-right shunt. All were unsuitable for cardiac surgery or interventional therapy at the time the treatment had commenced. None of the infants improved while receiving diuretics, spironolactone, and digoxin alone, but improved after the addition of propanolol or metoprolol. None of the infants had problems during or after the subsequent operation. Parasympathetic activity reflected by parameters of variability in heart rate, such as the square root of adjacent RR-intervals, and the amount of adjacent RR-intervals greater than 50 milliseconds, improved in nearly all infants during beta blockade. On the other hand, parameters of variability in heart rate reflecting sympathetic activity did not change. Parasympathetic activity reflected the clinical state of nearly all the infants. These parameters, therefore, seem to be a good non-clinical parameter, showing the optimal treatment for heart failure in an ambulatory setting.

Diastolic left ventricular function Experimental study of the early filling period using the Voigt model.

BACKGROUND: The left ventricular (LV) diastolic function is usually described by the diastolic part of the LV pressure-volume relationship (PVR). The mathematical analysis of the PVR provides parameters of diastolic LV as well as myocardial function. Up to now, all approaches assume the myocardium as a passive elastic medium. This implies that each increase in LV volume is associated with a corresponding increase in LV pressure. Obviously this does not agree with actual PVR's during the LV early filling phase, where a decrease of pressure (due to relaxation) can be observed. Therefore, we analysed the LV diastolic PVR using the Voigt model to provide a better understanding of the concomitant processes of relaxation and filling especially during the early diastole. METHODS AND RESULTS: LV volumes and pressures were measured in an experimental study (6 pigs) using biplane cineangiography (100 frames/s) and simultaneous pressure measurements (catheter tip manometer). LV volumes were determined from all cine frames of total cardiac cycles. Instantaneous (beat to beat) changes in duration (Deltat(f)) of the LV filling period were achieved by atrial stimulation and by releasing post-extrasystolic beats. A total of 26 PVR's with different Deltat(f) were evaluated. According to the Voigt model the compliance (product of the resting volume V(0) and the elastic coefficients) of the total muscle fibre (V(0).K(tot)) and of the serial elastic element (V(0).K(se)) were calculated (average: V(0).K(tot) = 3.43 ml/ mmHg; V(0).K(se) = 5.07 ml/mmHg; n = 26). The interindividual differences between the compliances were in some individuals significant (V(0).K(tot): p < 5% in 6 of 15 Wilcoxon tests ; V(0).K(se): p < 5% in 3 of 15 Wilcoxon tests) but the intraindividual range of these parameters (due to different Deltat(f)) were in some cases as pronounced as the interindividual differences. CONCLUSIONS: As in 22 of 26 measurements V(0).K(tot) is less than V(0).K(se) it must be concluded that the early diastolic PVR cannot be described by passive elasticity and the laws of elastomechanics only. These inconsistencies can be explained by the early diastolic LV suction (untwisting) as well as by recent findings regarding the titin filament. Both mechanisms augment LV diastolic filling even in unfavourable working conditions (shortened filling) such as exercise.

Long term follow-up of left ventricular performance and size of the great arteries before and after one- and two-stage arterial switch operation of simple transposition.

OBJECTIVE: Long-term angiographic evaluation of left ventricular performance and size of the great arteries after one-stage neonatal versus two-stage arterial switch operation (ASO) of simple transposition. METHODS: Analysis of cineangiographic studies obtained during the process of two-stage ASO for 34 patients and after neonatal repair for 52 patients. RESULTS: At early follow-up after two-stage ASO the left ventricular enddiastolic volume (LVEDV) was +1.8 standard deviations (S.D.) larger than LVEDV of control patients, but normalized completely (0.0 S.D.) at late follow-up. In contrast, after neonatal repair the LVEDV was always normal, and the median EF was significantly higher than after two-stage ASO (73 vs. 68%). The diameters of the native pulmonary annulus and sinus increased significantly after pulmonary artery banding to +4.5 and +4.8 S.D., respectively. After ASO, a significant decrease of the respective sizes occurred from early to late follow-up (annulus: +6.0 to +2.1 S.D.; sinus: +7.1 to +4.1 S.D.). After neonatal ASO the neoaortic annulus and sinus were only +1.5 and +2.7 S.D. larger than the comparable normal structures. The differences to the two-stage group were significant. In both groups, the neoaortic anastomosis had no diameters significantly different from normal. After one- and two-stage repair, the size of the neopulmonary annulus and sinus decreased similarly in both groups from early to late follow-up (annulus +0.9 to -2.4 S.D.; +0.3 to -2.8 S.D.; sinus: -0.7 to -1.6 S.D.; -0.7 to -1.8 S.D.). CONCLUSIONS: Neonatal ASO has definite advantages over two-stage repair concerning LV-performance and the degree of dilation of the neoaortic root. The significantly reduced size of the neopulmonary root after both procedures is remarkable, but fortunately mostly without clinical significance.