Towards a more balanced understanding of motor control systems

Roberts's book provides a reasonably thorough guide to the physiology and biomechanics of balance, unfortunately the discussion of the neural and cognitive aspects of motor control is less satisfactory. We propose that Roberts's statement of the problem of balance control should be extended to include control of non-equilibrium states, and we discuss sensorimotor calibration and integration in the context of maturation of the organism.Peer reviewe

Differences in intestinal size, structure, and function contributing to feed efficiency in broiler chickens reared at geographically distant locations

The contribution of the intestinal tract to differences in residual feed intake (RFI) has been inconclusively studied in chickens so far. It is also not clear if RFI-related differences in intestinal function are similar in chickens raised in different environments. The objective was to investigate differences in nutrient retention, visceral organ size, intestinal morphology, jejunal permeability and expression of genes related to barrier function, and innate immune response in chickens of diverging RFI raised at 2 locations (L1: Austria; L2: UK). The experimental protocol was similar, and the same dietary formulation was fed at the 2 locations. Individual BW and feed intake (FI) of chickens (Cobb 500FF) were recorded from d 7 of life. At 5 wk of life, chickens (L1, n = 157; L2 = 192) were ranked according to their RFI, and low, medium, and high RFI chickens were selected (n = 9/RFI group, sex, and location). RFI values were similar between locations within the same RFI group and increased by 446 and 464 g from low to high RFI in females and males, respectively. Location, but not RFI rank, affected growth, nutrient retention, size of the intestine, and jejunal disaccharidase activity. Chickens from L2 had lower total body weight gain and mucosal enzyme activity but higher nutrient retention and longer intestines than chickens at L1. Parameters determined only at L1 showed increased crypt depth in the duodenum and jejunum and enhanced paracellular permeability in low vs. high RFI females. Jejunal expression of IL1B was lower in low vs. high RFI females at L2, whereas that of TLR4 at L1 and MCT1 at both locations was higher in low vs. high RFI males. Correlation analysis between intestinal parameters and feed efficiency metrics indicated that feed conversion ratio was more correlated to intestinal size and function than was RFI. In conclusion, the rearing environment greatly affected intestinal size and function, thereby contributing to the variation in chicken RFI observed across locations

Cylindrical, periodic surface lattice — theory, dispersion analysis, and experiment

A two-dimensional surface lattice of cylindrical topology obtained via perturbing the inner surface of a cylinder is considered. Periodic perturbations of the surface lead to observation of high-impedance, dielectric-like media and resonant coupling of surface and non-propagating volume fields. This allows synthesis of tailored-for-purpose "coating" material with dispersion suitable, for instance, to mediate a Cherenkov type interaction. An analytical model of the lattice is discussed and coupled-wave equations are derived. Variations of the lattice dispersive properties with variation of parameters are shown, illustrating the tailoring of the structure's electromagnetic properties. Experimental results are presented showing agreement with the theoretical model

Prevalence of HLA-B*5701 in a Kenyan population with HIV infection

We read with interest the article published in your Journal entitled “Real-world persistence with antiretroviral therapy for HIV in the United Kingdom: a multicentre retrospective cohort study”1 which concluded that treatment discontinuation attributable to toxicity profile is not an uncommon event. They also acknowledged lack of data collection on HLA-B*5701 status, which would heavily influence initial ART regimen and the choice to discontinue medication. Of the 25.6 million living with Human Immunodeficiency Virus (HIV) in Africa, an estimated 1.6 million people live in Kenya.2 With an HIV prevalence of 5.6%, Kenya has upscaled HIV treatment and care in the past 10 years to cover 80% of those requiring therapy.2 The current Kenyan guidelines, as in the case of many developing countries, rely on WHO guidelines.3,4 Abacavir is a nucleoside reverse transcriptase inhibitor (NRTI) used for treating HIV infection and is recommended as both first and second line drug options. A barrier to prescribing of abacavir in Kenya is the fear of Abacavir Hypersensitivity Reaction, and this has been compounded by the lack of availability of testing for HLA-B*5701 testing. The Kenyan population is heterogeneous, consisting of 42 tribes with the main ethnic groups being Bantu, Nilotes and Cushites. In our study, we have determined the prevalence of HLAB* 5701 in the black HIV positive population in Kenya using a cross sectional epidemiological survey. We recruited 1004 patients from three HIV centers: the Aga Khan University Hospital Nairobi, Mbagathi Hospital and Machakos Hospital in Kenya after ethics approval was sought from the Research Ethics Committee in Aga Khan University and from the ethics boards of Mbagathi and Machakos hospitals

Does outstretching the arms improve postural stability?

We spontaneously outstretch our arms when standing upon challenging surfaces, yet the effect of stretching the arms upon postural stability is unknown. We investigated whether stretching out the arms laterally improves postural control during tandem stance on a narrow beam. Twelve healthy participants stood upon a beam, right foot in front of the left foot, for 30 seconds with arms outstretched or down to the side, with eyes open and closed. Mediolateral head movement was characterised by root mean square amplitude (RMS), sway path, velocity during the largest excursion and power spectrum. Spectra for lateral forces from a force platform beneath the beam were also recorded. Outstretching the arms significantly reduced RMS, sway path and velocity of maximum displacement of head movement with eyes closed but not with eyes open. A similar trend was present in the power spectra of head motion and sway platform lateral forces. In conclusion, outstretching the arms helps postural stability in challenging situations such as tandem stance on a narrow beam with eyes closed. Although the exact mechanisms require further investigation, the effects are most likely mediated by changes in segmental inertia and the ability to make corrective arm movements

Genome-wide association studies for feedlot and growth traits in cattle

A genome wide-association study for production traits in cattle was carried out using genotype data from the 10K Affymetrix (Santa Clara, CA) and the 50K Illumina (San Diego, CA) SNP chips. The results for residual feed intake (RFI), BW, and hip height in 3 beef breed types (Bos indicus, Bos taurus, and B. indicus × B. taurus), and for stature in dairy cattle, are presented. The aims were to discover SNP associated with all traits studied, but especially RFI, and further to test the consistency of SNP effects across different cattle populations and breed types. The data were analyzed within data sets and within breed types by using a mixed model and fitting 1 SNP at a time. In each case, the number of significant SNP was more than expected by chance alone. A total of 75 SNP from the reference population with 50K chip data were significant (P < 0.001) for RFI, with a false discovery rate of 68%. These 75 SNP were mapped on 24 different BTA. Of the 75 SNP, the 9 most significant SNP were detected on BTA 3, 5, 7, and 8, with P ≤ 6.0 × 10 . In a population of Angus cattle divergently selected for high and low RFI and 10K chip data, 111 SNP were significantly (P < 0.001) associated with RFI, with a false discovery rate of 7%. Approximately 103 of these SNP were therefore likely to represent true positives. Because of the small number of SNP common to both the 10K and 50K SNP chips, only 27 SNP were significantly (P < 0.05) associated with RFI in the 2 populations. However, other chromosome regions were found that contained SNP significantly associated with RFI in both data sets, although no SNP within the region showed a consistent effect on RFI. The SNP effects were consistent between data sets only when estimated within the same breed type

Through the eyes of a young carer: A photo elicitation study of protective resilience.

Caregiving is recognised as a source of stress with potential for negative health impacts as well as positive outcomes and development of resilience. For young carers, children, and adolescents providing care for close family members, adaptation through resilience is crucial, yet work using a resilience approach is limited. This study explored protective factors and pathways to resilience in a sample of young carers, through application of the socioecological model in caring relationships. An in-depth qualitative approach was used, with in-person interviews facilitated by auto-driven photo elicitation. Deductive thematic analysis was applied, framed by three levels (individual, community, and society) of the socioecological model of resilience. Twelve participants (nine girls and three boys) aged 5–18 years, each providing care to a family member, were recruited using opportunity and volunteer sampling via carers’ centres in the southwest of England. Ten key themes were identified, four at the individual level: pre-empting challenges and planning, cognitive strategies, emotional strategies, and seeking solitude; three at the community level: family support, friendships, and pets and inanimate objects; and three at the society level: professional support, access to caregiver activities and community, and being outdoors. The location of themes at each level indicated relevance of the socioecological model to identification of protective factors in a young carer population. These findings have important applications for guidance to charities and organisations supporting young carers. Identification of factors that promote resilience offers support for the development of well-informed interventions, which harness these protective factors to develop resilience and improve health for young carers