Correlation-based ultrasound imaging of strong reflectors with phase coherence filtering.

Two main metrics are usually employed to assess the quality of medical ultrasound (US) images, namely the contrast and the spatial resolution. A number of imaging algorithms have been proposed to improve one of those metrics, often at the expense of the other one. This paper presents the application of a correlation-based ultrasound imaging method, called Excitelet, to medical US imaging applications and the inclusion of a new Phase Coherence (PC) metric within its formalism. The main idea behind this algorithm, originally developed and validated for Non-Destructive Testing (NDT) applications, is to correlate a reference signal database with the measured signals acquired from a transducer array. In this paper, it is shown that improved lateral resolutions and a reduction of imaging artifacts are obtained over the Synthetic Aperture Focusing Technique (SAFT) when using Excitelet in conjunction with a PC filter. This novel method shows potential for the imaging of specular reflectors, such as invasive surgical tools. Numerical and experimental results presented in this paper demonstrate the benefit, in terms of contrast and resolution, of using the Excitelet method combined with PC for the imaging of strong reflectors.

Does the addition of virtual reality training to a standard program of inpatient rehabilitation improve sitting balance ability and function after stroke? Protocol for a single-blind randomized controlled trial.

BACKGROUND: Sitting ability and function are commonly impaired after stroke. Balance training has been shown to be helpful, but abundant repetitions are required for optimal recovery and patients must be motivated to perform rehabilitation exercises repeatedly to maximize treatment intensity. Virtual reality training (VRT), which allows patients to interact with a virtual environment using computer software and hardware, is enjoyable and may encourage greater repetition of therapeutic exercises. However, the potential for VRT to promote sitting balance has not yet been explored. The objective of this study is to determine if supplemental VRT-based sitting balance exercises improve sitting balance ability and function in stroke rehabilitation inpatients. METHODS/DESIGN: This is a single-site, single-blind, parallel-group randomized control trial. Seventy six stroke rehabilitation inpatients who cannot stand independently for greater than one minute but can sit for at least 20 minutes (including at least one minute without support) are being recruited from a tertiary-care dedicated stroke rehabilitation unit. Participants are randomly allocated to experimental or control groups. Both participate in 10-12 sessions of 30-45 minutes of VRT performed in sitting administered by a single physiotherapist, in addition to their traditional therapy. The experimental group plays five games which challenge sitting balance while the control group plays five games which minimize trunk lean. Outcome measures of sitting balance ability (Function in Sitting Test, Ottawa Sitting Scale, quantitative measures of postural sway) and function (Reaching Performance Scale, Wolf Motor Function Test, quantitative measures of the limits of stability) are administered prior to, immediately following, and one month following the intervention by a second physiotherapist blind to the participant's group allocation. DISCUSSION: The treatment of sitting balance post-stroke with VRT has not yet been explored. Results from the current study will provide important evidence for the use of low-cost, accessible VRT as an adjunct intervention to increase sitting balance in lower-functioning patients receiving inpatient rehabilitation. The motivating and enjoyable attributes of VRT may increase exercise dosage, leading to improved function and optimal results from rehabilitation. TRIAL REGISTRATION: https://clinicaltrials.gov/; Identifier: NCT02285933. Registered 06 November 2014. Funded by the Heart & Stroke Foundation of Canada and a generous donation from Tony & Elizabeth Graham.

Historical epidemiology of hepatitis C virus (HCV) in selected countries.

Chronic infection with hepatitis C virus (HCV) is a leading indicator for liver disease. New treatment options are becoming available, and there is a need to characterize the epidemiology and disease burden of HCV. Data for prevalence, viremia, genotype, diagnosis and treatment were obtained through literature searches and expert consensus for 16 countries. For some countries, data from centralized registries were used to estimate diagnosis and treatment rates. Data for the number of liver transplants and the proportion attributable to HCV were obtained from centralized databases. Viremic prevalence estimates varied widely between countries, ranging from 0.3% in Austria, England and Germany to 8.5% in Egypt. The largest viremic populations were in Egypt, with 6,358,000 cases in 2008 and Brazil with 2,106,000 cases in 2007. The age distribution of cases differed between countries. In most countries, prevalence rates were higher among males, reflecting higher rates of injection drug use. Diagnosis, treatment and transplant levels also differed considerably between countries. Reliable estimates characterizing HCV-infected populations are critical for addressing HCV-related morbidity and mortality. There is a need to quantify the burden of chronic HCV infection at the national level.

Strategies to manage hepatitis C virus (HCV) disease burden.

The number of hepatitis C virus (HCV) infections is projected to decline while those with advanced liver disease will increase. A modeling approach was used to forecast two treatment scenarios: (i) the impact of increased treatment efficacy while keeping the number of treated patients constant and (ii) increasing efficacy and treatment rate. This analysis suggests that successful diagnosis and treatment of a small proportion of patients can contribute significantly to the reduction of disease burden in the countries studied. The largest reduction in HCV-related morbidity and mortality occurs when increased treatment is combined with higher efficacy therapies, generally in combination with increased diagnosis. With a treatment rate of approximately 10%, this analysis suggests it is possible to achieve elimination of HCV (defined as a >90% decline in total infections by 2030). However, for most countries presented, this will require a 3-5 fold increase in diagnosis and/or treatment. Thus, building the public health and clinical provider capacity for improved diagnosis and treatment will be critical.

The present and future disease burden of hepatitis C virus (HCV) infection with today's treatment paradigm.

The disease burden of hepatitis C virus (HCV) is expected to increase as the infected population ages. A modelling approach was used to estimate the total number of viremic infections, diagnosed, treated and new infections in 2013. In addition, the model was used to estimate the change in the total number of HCV infections, the disease progression and mortality in 2013-2030. Finally, expert panel consensus was used to capture current treatment practices in each country. Using today's treatment paradigm, the total number of HCV infections is projected to decline or remain flat in all countries studied. However, in the same time period, the number of individuals with late-stage liver disease is projected to increase. This study concluded that the current treatment rate and efficacy are not sufficient to manage the disease burden of HCV. Thus, alternative strategies are required to keep the number of HCV individuals with advanced liver disease and liver-related deaths from increasing.

The role of a dedicated staff psychiatrist in modern burn centers.

Psychiatric disorders may be more common in burn-injured subjects than in the general population, and oftentimes contribute to the injury itself. Even in the absence of underlying psychiatric illnesses, burn patients may still benefit from a psychiatric evaluation during and after their hospitalization. In this regard, we included a dedicated psychiatry service in our multidisciplinary burn team. We review herein the course of burn patients that were offered psychiatric evaluation and highlight the benefits of such a program. We conducted an IRB-approved retrospective chart review of burn subjects admitted to our institution between June 15, 2009 and April 30, 2010 and identified 83 patients that were examined by our psychiatrist. Indications for consultation, history of psychiatric illness and substance abuse, as well as administered drugs, were recorded. Among the 83 evaluated patients, 48 (57.8%) had a preexisting psychiatric disorder and 36 (43.4%) suffered from substance abuse. The most common indications for consultation were pain (28.1%), alcohol dependence (25.8%), anxiety (24.7%), illicit drug abuse (16.8%), depression (15.7%), post-traumatic stress disorder (8.9%), and sleep disturbances (8.9%). Pharmacotherapy was initiated in 75 patients (90.3%). 31 (37.3%) had neither a psychiatric disorder nor a history of substance abuse, although 26 of them (83.9%) still received drugs for psychiatric conditions. The inclusion of a dedicated psychiatrist as part of our burn team has improved our comprehensive burn care. In the overwhelming majority of cases, even in the absence of preexisting psychiatric illnesses, consultation resulted in pharmacologic intervention and enhanced patient care.

Les troubles psychiatriques peuvent être plus fréquents chez les patients brûlés que dans la population générale, et contribuent souvent à la blessure elle-même. Même en l'absence de maladies psychiatriques sous-jacents, les patients brûlés peuvent encore bénéficier d'une évaluation psychiatrique pendant et après leur hospitalisation. À cet égard, nous avons inclus un service de psychiatrie dédié à notre équipe multidisciplinaire pour la gestion des brûlures. Nous examinons ici les cours de patients brûlés à qui une évaluation psychiatrique a été proposée et nous mettons en évidence les avantages d'un tel programme. Nous avons effectué un examen rétrospectif - approuvé par les CPP - des patients brûlés admis dans notre institution entre le 15 Juin 2009 et le 30 Avril, 2010, à partir de lequel nous avons identifié 83 patients qui ont été examinés par notre psychiatre. Nous avons enregistré les indications pour la consultation, les antécédents de maladie psychiatrique et la toxicomanie, ainsi que les médicaments administrés. Parmi les 83 patients évalués, 48 (57,8 %) avaient un trouble psychiatrique préexistante et 36 (43,4%) a souffert de l'abus de substances. Les indications les plus fréquentes de consultation étaient la douleur (28,1%), la dépendance à l'alcool (25,8%), l'anxiété (24,7%), l'abus de drogues illicites (16,8%), la dépression (15,7%), les troubles de stress post-traumatique (8,9%), et troubles du sommeil (8,9%). La pharmacothérapie a été instaurée dans 75 patients (90,3%). 31 (37,3%) ne présentaient pas de troubles psychiatriques ni une histoire d'abus de substance mais quand même 26 d'entre eux (83,9 %) ont reçu des médicaments pour des troubles psychiatriques. L'inclusion d'un psychiatre spécialisé dans le cadre de notre équipe a amélioré notre système complet de soins aux brulés. Dans l'écrasante majorité des cas, même en l'absence des maladies psychiatriques préexistantes, la consultation a donné lieu à une intervention pharmacologique et a amélioré les soins aux patients.

Voluntary and automatic recruitment of superficial and deep abdominal muscles in adults with and without cystic fibrosis.

UNLABELLED: Recruitment patterns of the superficial and deep abdominal muscles have been well documented in the general population, but not in a group of individuals with a chronic cough, such as individuals with cystic fibrosis (CF), which may alter the recruitment patterns between the abdominal muscles. Therefore the two objectives of this study were (1) to identify whether recruitment of the superficial and deep abdominal muscles during abdominal hollowing (AH) and unilateral leg load (ULL) tasks differed between individuals with CF and a non-CF control group (C); and (2) to compare the muscle activity between the superficial and deep abdominal muscles across these tasks. METHODS: Twenty-eight participants (14 with CF and 14 controls) performed (i) AH in supine at three target pressures of a pressure biofeedback unit (PBU) and (ii) a right-sided ULL. Surface electromyography (EMG) of the abdominal muscles was recorded and the amplitude of the signal was normalized to a maximum value (% max). RESULTS: A 3-way repeated measures ANOVA showed a muscle × task interaction during the AH, but no between group differences. Bonferonni post hoc tests on pooled data showed the deep abdominal muscles to be significantly more active than the superficial muscles. A 2-way repeated measure ANOVA indicated no group differences during the ULL. DISCUSSION: The results of this study demonstrate that adults with stable CF do not recruit their abdominal muscles differently from healthy control subjects during the AH and the ULL tasks. This suggests that coughing is not a risk factor for developing abdominal muscles imbalances in adults with cystic fibrosis.

Demyelinating sensorimotor polyneuropathy associated with the use of sirolimus: a case report.

Liver transplantation is associated with a number of neurological complications. We herein report a case of chronic inflammatory demyelinating polyneuropathy associated with the use of sirolimus-based immunosuppression. The patient was treated by converting the immunosuppression from sirolimus to cyclosporine and by a short course of oral steroids. Following this, we observed almost complete clinical and electrophysiologic resolution of this syndrome. We believe that this is the first described case of such a complication occurring in association with sirolimus. This immunosuppressive agent can, therefore, lead to neurological complications similar to the ones that have been observed with calcineurin inhibitors.

Severe haemorrhage following abdominal paracentesis for ascites in patients with liver disease.

BACKGROUND: Bleeding is a recognized complication of abdominal paracentesis. Special concern has been raised when it is performed in patients with liver failure because of coagulation disorders and collaterals in the abdominal wall. AIM: To assess the clinical characteristics of patients who developed haemorrhagic complications after paracentesis. METHODS: We reviewed all cases of severe haemorrhage occurring after paracentesis in patients admitted to the Liver Unit of our institution between 1994 and 2004. RESULTS: Nine cases were identified among 4729 procedures. The occurrence of severe haemorrhage represented 0.19% of all procedures with a death rate of 0.016%. Bleeding was not related to operator experience, elevated international normalized ratio or low platelets. It occurred in patients with high model for end-stage liver disease and Child-Pugh scores. Furthermore, some degree of renal failure was present in all but one patient. CONCLUSION: Severe haemorrhage after abdominal paracentesis in patients with liver disease occurs in 0.2% of cases. It occurs in patients with severe liver failure and is often associated with significant pre-existing renal dysfunction.

Anti-apoptotic effect of insulin on normal hepatocytes in vitro and in vivo.

Liver growth factors are known to be anti-apoptotic for hepatocytes. The potential of insulin, a liver co-mitogen, has not been thoroughly evaluated. We studied the anti-apoptotic role of insulin on primary cultures of rat hepatocytes exposed to transforming growth factor-beta (TGF-beta) as the apoptotic agent and in the left portal vein ligation model (LVPL) of liver atrophy. Results show that insulin decreases apoptosis of TGF-beta-treated hepatocyte cultures by 43% (P < 0.002) and the alanine amino transferase (ALT) release by 49% (P < 0.001). Left lobes of LPVL animals displayed a significant increase in the levels of TGF-beta mRNA. In LPVL rats receiving continuous infusion of insulin in the left lobes, the weight of the atrophic lobes was higher over a 7-day period in comparison to control animals. This was associated with lower levels of serum ALT and with a five-fold decrease in the apoptotic index in the left lobes (P < 0.0001). Induction of Akt phosphorylation and increased expression of Bcl-xl were observed in the left lobes of insulin-treated animals. In conclusion, these results show that insulin is anti-apoptotic for normal hepatocytes both in vitro and in vivo and that the action of insulin is associated with increased Bcl-xl expression and Akt activation.

EMG frequency content changes with increasing force and during fatigue in the quadriceps femoris muscle of men and women.

The purpose of this study was to determine the effect of gender on changes in electromyographic (EMG) signal characteristics of the quadriceps muscles with increasing force and with fatigue. A total of fourteen healthy adults (seven men, seven women) participated in the study. Subjects had to perform isometric ramp contractions in knee extension with the force gradually increasing from 0 to 100% of the maximal voluntary contraction (MVC) in a 6-s period. Subjects then performed a fatigue task, consisting of a sustained maximum isometric knee extension contraction held until force decreased below 50% of the pre-fatigue MVC. Subjects also performed a single ramp contraction immediately after the fatigue task. The Root Mean Square (RMS) amplitude, mean power frequency (MPF) and median frequency (MF) of EMG signals obtained from the vastus lateralis, vastus medialis and rectus femoris were calculated at nine different force levels from the ramp contractions (10, 20, 30, 40, 50, 60, 70, 80 and 90% MVC), as well as every 5 s during the fatigue task. The main results were a more pronounced increase in EMG RMS amplitude for the three muscles and in MPF for the VL muscle with force in men compared with women. No significant effect of gender was found with regards to fatigue. These observations most likely reflect a moderately greater type II fiber content and/or area in the VL muscle of men compared to that of women.

Neuromuscular fatigue of elbow flexor muscles of dominant and non-dominant arms in healthy humans.

The purpose of this study was to assess differences in fatigue-related changes in variables related to structures within the neuromuscular system, between the dominant and non-dominant elbow flexor muscles of right-handed individuals. Two experimental sessions were performed on the right arm and one on the left arm. For each session, maximum voluntary torque, level of voluntary activation, M-wave amplitude, twitch/train or twitch/doublet torque ratio and EMG median frequency were obtained before and up to 20 min after a sustained maximum isometric fatigue task. Our main results were: 1) reproducible fatigue-induced changes in all variables of interest between the two sessions performed with the right arm, 2) significantly greater failure in voluntary activation and neuromuscular propagation with sustained activity for the non-dominant compared with dominant side, and 3) no effect of dominance on MVC torque, endurance time, and fatigue-induced changes in EMG median frequency and elicited torques. These results suggest that the preferential use of elbow flexor muscles with the dominant arm leads to more fatigue resistance in certain structures/mechanisms of the neuromuscular system, but not in others.

Changes in upper limb joint torque patterns and EMG signals with fatigue following a stroke.

PURPOSE: Little is known concerning changes in neuromuscular fatigue following a stroke. The purpose of this study was to evaluate the effect of a stroke on fatigue-related changes in upper limb torque patterns and electromyographic signals. METHOD: The paretic and non-paretic upper limb of 10 adults (51-79 years) who had a stroke (time since stroke: 3-75 months) were compared. Subjects had to perform a fatigue task consisting of a sustained maximal isometric contraction in elbow flexion until torque decreased to below 50% of initial. The main variables of interest assessed before, during and after fatigue were: (1) the torque in elbow flexion, as well as associated forces/torques at the shoulder and forearm; (2) the level of voluntary activation; (3) the amplitude (RMS); and (4) frequency content (median frequency) of electromyographic signals. RESULTS: Compared to the non-paretic side, the paretic side showed a lower level of voluntary activation and higher relative torque levels at the forearm and shoulder which could both be exaggerated with fatigue, and a lesser fatigue-related decrease in median frequency. CONCLUSIONS: Thus, greater fatigue-related changes in features of the central command (ability to maximally activate a muscle and ability to isolate effort to a muscle group) were observed for the paretic compared with the non-paretic side. This could be a confounding factor when assessing changes in peripheral measures of fatigue following a stroke using voluntary contractions.

Do enzymatic hydrolyzability and Simons' stain reflect the changes in the accessibility of lignocellulosic substrates to cellulase enzymes?

In an attempt to elucidate the impact of substrate accessibility to cellulases on the susceptibility of lignocellulosic substrates to enzymatic hydrolysis, a hydrogen peroxide treated, Douglas fir kraft pulp was dried using several methods with varying levels of intensity. Oven-drying at 50 and 100 degrees C, air-drying, and freeze-drying methods were employed to remove the interfibrillar water from the pulp samples. Subsequently, the never-dried and variably dried pulps were hydrolyzed using a commercial cellulase preparation supplemented with additional beta-glucosidase. Drying reduced the susceptibility of the substrates to enzymatic hydrolysis, which can be attributed to the hornifying effect that drying has on fibers. This effect was more pronounced for the fibers that were oven-dried at 100 degrees C (23% reduction) and 50 degrees C (15% reduction), and there was a good correlation between the Simons's stain results and the enzymatic digestibility of the dried pulps. These observations indicated that drying significantly reduced the population of larger pores and that the partial closure of larger pores created a large number of smaller pores that were not accessible to the displacement dye molecules (orange dye). The inaccessibility of the cellulose to the enzymes, due to the collapse or closure of the large pores, appears to be the primary reason for the lower susceptibility of the dried pulps to enzymatic hydrolysis.

Effect of aging on fatigue characteristics of elbow flexor muscles during sustained submaximal contraction.

The purpose of this study was to compare fatigue-related measures of central and peripheral mechanisms between young and elderly subjects for a task performed with elbow flexor muscles. Ten young and nine elderly subjects performed a sustained submaximal fatigue task at 35% of their maximum voluntary contraction torque. Measures of neuromuscular function, reflecting changes in neuromuscular propagation, voluntary activation, excitation-contraction-relaxation processes, and metabolite buildup, were taken before, during, and after the fatigue task. The main results were the absence of neuromuscular propagation failure in either young or elderly subjects, the presence of central fatigue at the end of the fatigue task in 7 of 9 elderly but only 3 of 10 young subjects, and lesser changes in twitch torque contraction-relaxation variables and electromyographic median frequency in elderly compared with young subjects. The lesser fatigue-related changes in twitch contraction speed and median frequency in elderly compared with young subjects could reflect the increase in type I-to-type II fiber area reported with old age. The presence of significant central fatigue can apparently minimize some of the potential differences present in peripheral fatigue sites.

BMP-2 stimulates tyrosinase gene expression and melanogenesis in differentiated melanocytes.

Cells of the vertebrate neural crest (crest cells) differentiate in vitro to melanocytes and sympathoadrenal (SA) progenitor cells. We have shown previously, using primary J. quail neural crest cultures, the combinatorial effect of bone morphogenetic protein-2 (BMP-2) and cAMP signaling on SA cell development. Herein, we report that in primary J. quail neural crest cultures, BMP-2 and cAMP signaling similarly exert a combinatorial effect on melanocyte development. We demonstrate that BMP-2 treatment of neural crest cells increases melanogenesis by promoting the synthesis of melanin. This increased melanin synthesis by BMP-2 is effected by the selective increase in the transcription of the tyrosinase gene, encoding the rate-limiting enzyme of the melanin biosynthetic pathway. By contrast, BMP-2 exerts no effect on the expression of the tyrosine-related proteins 1 and 2 (Tyrpl and Dct), also involved in the melanin biosynthetic process, or on the expression of microphalmia (Mitf) gene, supporting the fact that BMP-2 does not affect melanocyte differentiation. Employing transient transfection analysis of tyrosinase-reporter constructs in B16 melanoma cells, we demonstrate that the BMP-2 response-element is localized between 900 and 1,100 bp upstream from the tyrosinase transcriptional start site. These studies support a role for BMP-2 in melanogenesis by selectively targeting the expression of the tyrosinase gene involved in melanin biosynthesis.

Role of EGF receptor tyrosine kinase activity in antiapoptotic effect of EGF on mouse hepatocytes.

The apoptotic Fas pathway is potentially involved in the pathogenesis of liver diseases. Growth factors, such as epidermal growth factor (EGF), can protect cells against apoptosis induced by a variety of stimuli, including Fas receptor stimulation. However, the underlying mechanisms of this protection have yet to be determined. We investigated the involvement of EGF receptor (EGFR) tyrosine kinase (TK) activity in the antiapoptotic effect of EGF on primary mouse hepatocyte cultures. Cells undergoing apoptosis after treatment with anti-Fas antibody were protected by EGF treatment. This protection was significantly but partially decreased when cells were treated with two specific inhibitors of the TK activity of EGFR. Evaluation of the efficacy of these compounds indicated that they were able to abolish EGFR autophosphorylation and postreceptor events such as activation of mitogen-activated protein kinases and the phosphatidylinositol 3'-kinase pathways as well as increases in Bcl-x(L) mRNA and protein levels. This leads us to postulate that EGF exerts its antiapoptotic action partially through the TK activity of EGFR. In addition, our results suggest that Bcl-x(L) protein upregulation caused by EGF is linked to the TK activity of its receptor.

Differential expression of sympathoadrenal lineage-determining genes and phenotypic markers in cultured primary neural crest cells.

Bone morphogenetic protein-2 (BMP-2) promotes the development of primary neural crest cells grown in tissue culture to the sympathoadrenal (SA) lineage. Independent studies have characterized the expression patterns of SA-lineage genes in developing chicken embryo; however, studies using cultured primary neural crest cells have characterized only the expression patterns of the catecholaminergic markers, tyrosine hydroxylase (TH) and catecholamines (CAs). To further explore the molecular mechanisms that control SA-cell development using the in vitro model system, it is crucial to define the expression patterns of both the catecholaminergic markers and the genes regulating SA-lineage determination. Accordingly, we defined, in the absence and presence of BMP-2, the temporal expression patterns of TH and CA, the SA lineage-determining genes ASH-1, Phox2a, and Phox2b, the GATA-2 gene, and the pan-neuronal SCG10 gene. Comparison of these data with the reported temporal and spatial patterns of expression in vivo demonstrate that the inductive steps of SA-lineage determination, including the specification of neurotransmitter identity and neuronal fate, are recapitulated in the neural-crest culture system.