Motor learning in children with hemiplegic cerebral palsy : feedback effects on skill acquisition

Purpose. Augmented feedback is an important variable influencing motor learning. Previous studies show reduced feedback frequency benefits motor learning in young adults more than a comparison group of children, who benefit from frequent feedback during practice. It is unclear how motor and central nervous system differences in children with cerebral palsy may impact their use of feedback in motor skill acquisition. This study investigated the effect of augmented visual feedback (FB) on performance and learning of an upper extremity motor skill in children with spastic hemiplegic cerebral palsy (SHCP) as they practiced with their less affected arm, compared to typically developing children (TDC). Methods. Participants were 8-17 years with academic performance within two grade levels. Both TDC (n = 20) and participants with SHCP (n = 19) were screened for visual perception (MVPT-3) and manual dexterity (Box and Block). Children were divided into groups receiving frequent FB (100%) or faded FB (62%). Group differences for acquisition, retention, and reacquisition were compared in relation to FB level. Results. Both groups of children used visual FB to improve motor performance during skill practice. All children receiving 62% FB performed with greater error than children receiving 100% FB during the acquisition phase (p =.012), delayed retention no-feedback test (p =.017), and reacquisition phase (p =.042). Children with SHCP in both FB groups performed with significantly greater error than TDC during the entire acquisition phase (p \u3c .001), delayed retention no-feedback test (p = .031) and reacquisition phase (p = .001). While no significant within group feedback effect was found for children with SHCP, there was a trend for greater accuracy in the 100% group as compared to the 62% group during acquisition (p =.092) and this trend was seen again during reacquisition when FB was reintroduced (p =.092). Conclusions. Results suggest that for children with SHCP skill acquisition is furthered by visual FB regarding their movement accuracy. Children with SHCP use visual FB in a manner similar to TDC, although differences in learning were evident during the acquisition, delayed retention, and reacquisition phases. Further investigation is needed to determine clinical implications

Breath analysis by ultra-sensitive broadband laser spectroscopy detects SARS-CoV-2 infection

Rapid testing is essential to fighting pandemics such as COVID-19, the disease caused by the SARS-CoV-2 virus. Exhaled human breath contains multiple volatile molecules providing powerful potential for non-invasive diagnosis of diverse medical conditions. We investigated breath detection of SARS-CoV-2 infection using cavity-enhanced direct frequency comb spectroscopy (CE-DFCS), a state-of-the-art laser spectroscopic technique capable of a real-time massive collection of broadband molecular absorption features at ro-vibrational quantum state resolution and at parts-per-trillion volume detection sensitivity. Using a total of 170 individual breath samples (83 positive and 87 negative with SARS-CoV-2 based on Reverse Transcription Polymerase Chain Reaction tests), we report excellent discrimination capability for SARS-CoV-2 infection with an area under the Receiver-Operating-Characteristics curve of 0.849(4). Our results support the development of CE-DFCS as an alternative, rapid, non-invasive test for COVID-19 and highlight its remarkable potential for optical diagnoses of diverse biological conditions and disease states

Gene mutations and genomic rearrangements in the mouse as a result of transposon mobilization from chromosomal concatemers

Previous studies of the Sleeping Beauty (SB) transposon system, as an insertional mutagen in the germline of mice, have used reverse genetic approaches. These studies have led to its proposed use for regional saturation mutagenesis by taking a forward-genetic approach. Thus, we used the SB system to mutate a region of mouse Chromosome 11 in a forward-genetic screen for recessive lethal and viable phenotypes. This work represents the first reported use of an insertional mutagen in a phenotype-driven approach. The phenotype-driven approach was successful in both recovering visible and behavioral mutants, including dominant limb and recessive behavioral phenotypes, and allowing for the rapid identification of candidate gene disruptions. In addition, a high frequency of recessive lethal mutations arose as a result of genomic rearrangements near the site of transposition, resulting from transposon mobilization. The results suggest that the SB system could be used in a forward-genetic approach to recover interesting phenotypes, but that local chromosomal rearrangements should be anticipated in conjunction with single-copy, local transposon insertions in chromosomes. Additionally, these mice may serve as a model for chromosome rearrangements caused by transposable elements during the evolution of vertebrate genomes. © 2006 Geurts et al

UK construction companies’ strategies in the face of business cycles

Firms in the construction industry have always had to deal with the challenges of the economic cycle and develop strategies to deal with the resulting fluctuations in their business environment. In the context of the 2008–2011 double-dip recession in the UK, the results of a survey targeting the top one hundred construction companies in the UK are reported here. This research is particularly intended to assess whether the strategies of large companies in the construction sector, when faced with the issues associated with the variation in the economic cycle, have changed since the previous business cycle (i.e. the 1986–1990 boom followed by the 1990–1991 recession). The survey reveals the challenges that companies have faced, reports on company behaviour and on the policies adopted. While there are many similarities between policies adopted during the recessionary periods of the two cycles, the research found notable changes in attitudes towards diversification, human resource management and price bidding

Cover Image Defining the Cardiac Fibroblast Secretome in a Fibrotic Microenvironment

Background Cardiac fibroblasts (CFs) have the ability to sense stiffness changes and respond to biochemical cues to modulate their states as either quiescent or activated myofibroblasts. Given the potential for secretion of bioactive molecules to modulate the cardiac microenvironment, we sought to determine how the CF secretome changes with matrix stiffness and biochemical cues and how this affects cardiac myocytes via paracrine signaling. Methods and Results Myofibroblast activation was modulated in vitro by combining stiffness cues with TGF&beta;1 (transforming growth factor &beta; 1) treatment using engineered poly (ethylene glycol) hydrogels, and in vivo with isoproterenol treatment. Stiffness, TGF&beta;1, and isoproterenol treatment increased AKT (protein kinase B) phosphorylation, indicating that this pathway may be central to myofibroblast activation regardless of the treatment. Although activation of AKT was shared, different activating cues had distinct effects on downstream cytokine secretion, indicating that not all activated myofibroblasts share the same secretome. To test the effect of cytokines present in the CF secretome on paracrine signaling, neonatal rat ventricular cardiomyocytes were treated with CF conditioned media. Conditioned media from myofibroblasts cultured on stiff substrates and activated by TGF&beta;1 caused hypertrophy, and one of the cytokines in that media was insulin growth factor 1, which is a known mediator of cardiac myocyte hypertrophy. Conclusions Culturing CFs on stiff substrates, treating with TGF&beta;1, and in vivo treatment with isoproterenol all caused myofibroblast activation. Each cue had distinct effects on the secretome or genes encoding the secretome, but only the secretome of activated myofibroblasts on stiff substrates treated with TGF&beta;1 caused myocyte hypertrophy, most likely through insulin growth factor 1.</p

Cardiac Fibroblasts Mediate a Sexually Dimorphic Fibrotic Response to beta-Adrenergic Stimulation

Background Biological sex is an important modifier of cardiovascular disease and women generally have better outcomes compared with men. However, the contribution of cardiac fibroblasts (CFs) to this sexual dimorphism is relatively unexplored. Methods and Results Isoproterenol (ISO) was administered to rats as a model for chronic &beta;‐adrenergic receptor (&beta;‐AR)‐mediated cardiovascular disease. ISO‐treated males had higher mortality than females and also developed fibrosis whereas females did not. Gonadectomy did not abrogate this sex difference. To determine the cellular contribution to this phenotype, CFs were studied. CFs from both sexes had increased proliferation in vivo in response to ISO, but CFs from female hearts proliferated more than male cells. In addition, male CFs were significantly more activated to myofibroblasts by ISO. To investigate potential regulatory mechanisms for the sexually dimorphic fibrotic response, &beta;‐AR mRNA and PKA (protein kinase A) activity were measured. In response to ISO treatment, male CFs increased expression of &beta;1‐ and &beta;2‐ARs, whereas expression of both receptors decreased in female CFs. Moreover, ISO‐treated male CFs had higher PKA activity relative to vehicle controls, whereas ISO did not activate PKA in female CFs. Conclusions Chronic in vivo &beta;‐AR stimulation causes fibrosis in male but not female rat hearts. Male CFs are more activated than female CFs, consistent with elevated fibrosis in male rat hearts and may be caused by higher &beta;‐AR expression and PKA activation in male CFs. Taken together, our data suggest that CFs play a substantial role in mediating sex differences observed after cardiac injury. </div

Identification of functional differences between recombinant human α and β cardiac myosin motors

The myosin isoform composition of the heart is dynamic in health and disease and has been shown to affect contractile velocity and force generation. While different mammalian species express different proportions of α and β myosin heavy chain, healthy human heart ventricles express these isoforms in a ratio of about 1:9 (α:β) while failing human ventricles express no detectable α-myosin. We report here fast-kinetic analysis of recombinant human α and β myosin heavy chain motor domains. This represents the first such analysis of any human muscle myosin motor and the first of α-myosin from any species. Our findings reveal substantial isoform differences in individual kinetic parameters, overall contractile character, and predicted cycle times. For these parameters, α-subfragment 1 (S1) is far more similar to adult fast skeletal muscle myosin isoforms than to the slow β isoform despite 91% sequence identity between the motor domains of α- and β-myosin. Among the features that differentiate α- from β-S1: the ATP hydrolysis step of α-S1 is ~ten-fold faster than β-S1, α-S1 exhibits ~five-fold weaker actin affinity than β-S1, and actin·α-S1 exhibits rapid ADP release, which is >ten-fold faster than ADP release for β-S1. Overall, the cycle times are ten-fold faster for α-S1 but the portion of time each myosin spends tightly bound to actin (the duty ratio) is similar. Sequence analysis points to regions that might underlie the basis for this finding

Eccentric Exercise Activates Novel Transcriptional Regulation of Hypertrophic Signaling Pathways Not Affected by Hormone Changes

Unaccustomed eccentric exercise damages skeletal muscle tissue, activating mechanisms of recovery and remodeling that may be influenced by the female sex hormone 17β-estradiol (E2). Using high density oligonucleotide based microarrays, we screened for differences in mRNA expression caused by E2 and eccentric exercise. After random assignment to 8 days of either placebo (CON) or E2 (EXP), eighteen men performed 150 single-leg eccentric contractions. Muscle biopsies were collected at baseline (BL), following supplementation (PS), +3 hours (3H) and +48 hours (48H) after exercise. Serum E2 concentrations increased significantly with supplementation (P<0.001) but did not affect microarray results. Exercise led to early transcriptional changes in striated muscle activator of Rho signaling (STARS), Rho family GTPase 3 (RND3), mitogen activated protein kinase (MAPK) regulation and the downstream transcription factor FOS. Targeted RT-PCR analysis identified concurrent induction of negative regulators of calcineurin signaling RCAN (P<0.001) and HMOX1 (P = 0.009). Protein contents were elevated for RND3 at 3H (P = 0.02) and FOS at 48H (P<0.05). These findings indicate that early RhoA and NFAT signaling and regulation are altered following exercise for muscle remodeling and repair, but are not affected by E2

Interplay between Exonic Splicing Enhancers, mRNA Processing, and mRNA Surveillance in the Dystrophic Mdx Mouse

BACKGROUND: Pre-mRNA splicing, the removal of introns from RNA, takes place within the spliceosome, a macromolecular complex composed of five small nuclear RNAs and a large number of associated proteins. Spliceosome assembly is modulated by the 5′ and 3′ splice site consensus sequences situated at the ends of each intron, as well as by exonic and intronic splicing enhancers/silencers recognized by SR and hnRNP proteins. Nonsense mutations introducing a premature termination codon (PTC) often result in the activation of cellular quality control systems that reduce mRNA levels or alter the mRNA splicing pattern. The mdx mouse, a commonly used genetic model for Duchenne muscular dystrophy (DMD), lacks dystrophin by virtue of a premature termination codon (PTC) in exon 23 that also severely reduces the level of dystrophin mRNA. However, the effect of the mutation on dystrophin RNA processing has not yet been described. METHODOLOGY/PRINCIPAL FINDING: Using combinations of different biochemical and cellular assays, we found that the mdx mutation partially disrupts a multisite exonic splicing enhancer (ESE) that is recognized by a 40 kDa SR protein. In spite of the presence of an inefficient intron 22 3′ splice site containing the rare GAG triplet, the mdx mutation does not activate nonsense-associated altered splicing (NAS), but induces exclusively nonsense-mediated mRNA decay (NMD). Functional binding sites for SR proteins were also identified in exon 22 and 24, and in vitro experiments show that SR proteins can mediate direct association between exon 22, 23, and 24. CONCLUSIONS/SIGNIFICANCE: Our findings highlight the complex crosstalk between trans-acting factors, cis-elements and the RNA surveillance machinery occurring during dystrophin mRNA processing. Moreover, they suggest that dystrophin exon–exon interactions could play an important role in preventing mdx exon 23 skipping, as well as in facilitating the pairing of committed splice sites

Sex-specific pathways in early cardiac response to pressure overload in mice

Pressure overload (PO) first causes cardiac hypertrophy and then heart failure (HF), which are associated with sex differences in cardiac morphology and function. We aimed to identify genes that may cause HF-related sex differences. We used a transverse aortic constriction (TAC) mouse model leading to hypertrophy without sex differences in cardiac function after 2 weeks, but with sex differences in hypertrophy 6 and 9 weeks after TAC. Cardiac gene expression was analyzed 2 weeks after surgery. Deregulated genes were classified into functional gene ontology (GO) categories and used for pathway analysis. Classical marker genes of hypertrophy were similarly upregulated in both sexes (α-actin, ANP, BNP, CTGF). Thirty-five genes controlling mitochondrial function (PGC-1, cytochrome oxidase, carnitine palmitoyl transferase, acyl-CoA dehydrogenase, pyruvate dehydrogenase kinase) had lower expression in males compared to females after TAC. Genes encoding ribosomal proteins and genes associated with extracellular matrix remodeling exhibited relative higher expression in males (collagen 3, matrix metalloproteinase 2, TIMP2, and TGFβ2, all about twofold) after TAC. We confirmed 87% of the gene expression by real-time polymerase chain reaction. By GO classification, female-specific genes were related to mitochondria and metabolism and males to matrix and biosynthesis. Promoter studies confirmed the upregulation of PGC-1 by E2. Less downregulation of metabolic genes in female hearts and increased protein synthesis capacity and deregulation of matrix remodeling in male hearts characterize the sex-specific early response to PO. These differences could contribute to subsequent sex differences in cardiac function and HF