Sodium ion interactions with aqueous glucose: Insights from quantum mechanics, molecular dynamics, and experiment

In the last several decades, significant efforts have been conducted to understand the fundamental reactivity of glucose derived from plant biomass in various chemical environments for conversion to renewable fuels and chemicals. For reactions of glucose in water, it is known that inorganic salts naturally present in biomass alter the product distribution in various deconstruction processes. However, the molecular-level interactions of alkali metal ions and glucose are unknown. These interactions are of physiological interest as well, for example, as they relate to cation-glucose cotransport. Here, we employ quantum mechanics (QM) to understand the interaction of a prevalent alkali metal, sodium, with glucose from a structural and thermodynamic perspective. The effect on B-glucose is subtle: a sodium ion perturbs bond lengths and atomic partial charges less than rotating a hydroxymethyl group. In contrast, the presence of a sodium ion significantly perturbs the partial charges of α-glucose anomeric and ring oxygens. Molecular dynamics (MD) simulations provide dynamic sampling in explicit water, and both the QM and the MD results show that sodium ions associate at many positions with respect to glucose with reasonably equivalent propensity. This promiscuous binding nature of Na + suggests that computational studies of glucose reactions in the presence of inorganic salts need to ensure thorough sampling of the cation positions, in addition to sampling glucose rotamers. The effect of NaCl on the relative populations of the anomers is experimentally quantified with light polarimetry. These results support the computational findings that Na + interacts similarly with a- and B-glucose

Speech, Language and Communicative Ability in School-Aged Children with Cerebral Palsy and Speech Impairment

Abstract: The overall aim of this thesis was to explore and describe speech, language and communicative ability in school-aged children with cerebral palsy (CP) and speech impairment. The medical records of a population-based cohort of 129 children with CP born 1999–2002 in western Sweden were reviewed. Type of CP, motor functions and neuroimaging findings were analysed. Twenty-seven (21%) of the 129 children had speech impairment. Twenty-two (82%) of the 27 children took part in an assessment of speech, language, and communication skills. Consonant production, dysarthria, hypernasality and oral narratives were assessed. The children’s, the parents’, the teachers’ and the SLP’s opinions about the children’s communicative ability were also analysed. More than half of the children had severe problems with articulation of oral consonants. Speech production and non-verbal cognitive level correlated significantly and severe retelling ability problems occurred. Language ability and auditory memory correlated significantly with retelling ability. The children were mostly positive about their own communication. Parents and teachers rated them as having marked general communicative impairments. Parents’ and SLP’s ratings correlated significantly, whereas the parents and the teachers ratings did not. A comprehensive speech, language and communication test battery in which standardised tests are included is suggested for children with CP and speech impairment. The children’s own opinions and those of the key persons around them are also important to consider when planning intervention

Loss of selective wrist muscle activation in post-stroke patients

Purpose: Loss of selective muscle activation after stroke contributes to impaired arm function, is difficult to quantify and is not systematically assessed yet. The aim of this study was to describe and validate a technique for quantification of selective muscle activation of wrist flexor and extensor muscles in a cohort of post-stroke patients. Patterns of selective muscle activation were compared to healthy volunteers and test-retest reliability was assessed. Materials and methods: Activation Ratios describe selective activation of a muscle during its expected optimal activation as agonist and antagonist. Activation Ratios were calculated from electromyography signals during an isometric maximal torque task in 31 post-stroke patients and 14 healthy volunteers. Participants with insufficient voluntary muscle activation (maximal electromyography signal <3SD higher than baseline) were excluded. Results: Activation Ratios at the wrist were reliably quantified (Intraclass correlation coefficients 0.77-0.78). Activation Ratios were significantly lower in post-stroke patients compared to healthy participants (p < 0.05). Conclusion: Activation Ratios allow for muscle-specific quantification of selective muscle activation at the wrist in post-stroke patients. Loss of selective muscle activation may be a relevant determinant in assigning and evaluating therapy to improve functional outcome

Association between upper-limb isometric strength and handcycling performance in elite athletes

This study investigated the association among isometric upper-limb strength of handcyclists and sport-specific performance outcomes. At two international events, 62 athletes were tested on upper-limb strength, measured with an isometric-strength setup and with Manual Muscle Test (MMT). Horizontal force (F-z), effectiveness, rate of development, variability, and asymmetries were calculated for upper-limb pull and push. Performance measures were mean (POmean) and peak (POpeak) 20-s sprint power output and average time-trial velocity (TTvelocity). Regression models were conducted to investigate which pull and push strength variables associated strongest with performance measures. Additional regression analyses were conducted with an MMT sum score as predictor. Push and pull F-z showed the strongest associations with all outcomes. Combined push and pull F-z explained (p &lt; .001) 80-81% of variance of POmean and POpeak. For TTvelocity, only push F-z was included in the model explaining 29% of the variance (p &lt; .001). MMT models revealed weaker associations with sprint PO (R-2 = .38-.40, p &lt; .001) and TTvelocity (R-2 = .18, p = 0.001). The findings confirmed the relevance of upper-limb strength on handcycling performance and the significance of ratio-scaled strength measures. Isometric strength outcomes are adequate sport-specific indicators of impairment in handcycling classification, but future research should corroborate this notion and its potential to discriminate between sports classes

The use of in vitro peptide binding profiles and in silico ligand-receptor interaction profiles to describe ligand-induced conformations of the retinoid X receptor alpha ligand-binding domain

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