Biology subjects

Kerr, G.

Publications and source records attributed to Kerr, G..

3 recordsLinked to original sources

bioRxiv2018

Assessment of abduction movement in older people with painful shoulder: an analysis based on inertial sensors

Reduced range of motion in the shoulder can be a source of functional limitation. Current quantitative evaluation systems are limited to assessing the functionality or the maximum articular amplitudes in each of the planes of movement, both in isolation. These separate clinical evaluation systems may not allow the identification of the underlying impairments contributing to the functional limitation. The use of inertial sensors to quantify movement in addition to more common clinical assessments of the shoulder may allow clinicians to understand that are potentially unnoticed by the human eye. The main objective of this cross-sectional study was to generate an explanatory model for shoulder abduction based on data from inertial sensors. Shoulder abduction of thirteen older adults suffering from shoulder dysfunction was evaluated using two inertial sensors placed on the humerus and scapula. Movement variables (maximum angular mobility, angular peak of velocity, peak of acceleration) were used to explain the functionality of the upper limb (assessed using the Upper Limb Functional Index). Abduction movement of the shoulder was explained by six variables related to the mobility of the shoulder joint complex. A manova analysis was used to explain the results obtained on the functionality of the upper limb. The MANOVA model based on angular mobility explained 69% of the variance of the ULFI value (r-squared=0.69). The most relevant variables were the abduction-adduction of the humerus and the medial and lateral rotation of the scapula. However, given the limited sample size, none of these individual variables were statistically significant in the decomposition model on their own. The method used in the present study reveals the potential importance of the analysis of the scapular and humeral movements for comprehensive evaluation of the upper limb. Further research should include a wider sample and may seek to use this assessment technique in a range of potential clinical applications.

bioengineering↗

bioRxiv2017

Intrinsically photosensitive retinal ganglion cell mediated pupil function is impaired in Parkinson’s disease

Parkinsons disease is characterised by non-motor symptoms including sleep and circadian disruption, but the underlying aetiology is not well understood. Melanopsin-expressing intrinsically photosensitive Retinal Ganglion Cells (ipRGC) transmit light signals from the eye to brain areas controlling circadian rhythms and the pupil light reflex. Here we evaluate the hypothesis that these non-motor symptoms in people with Parkinsons disease may be linked to ipRGC dysfunction. Using chromatic pupillometry, we measured intrinsic (melanopsin-mediated) ipRGC and extrinsic (rod/cone photoreceptor-mediated) inputs to the pupil control pathway in a group of optimally medicated participants with a diagnosis of Parkinsons disease (PD, n = 17) compared to controls (n = 12). Autonomic tone was evaluated by measuring pupillary unrest in darkness. The PD participants underwent additional clinical assessments using the Unified Parkinsons disease Rating Scale (UPDRS) and the Hoehn and Yahr scale (H&Y).\n\nCompared to controls, the PD group demonstrated an attenuated pupil constriction amplitude in response to long wavelength pulsed stimulation, and reduced post-illumination pupil response (PIPR) amplitude in response to both short wavelength pulsed and sinusoidal stimulation. In the PD group, PIPR amplitude did not correlate with measures of sleep quality, retinal nerve fibre layer thickness, UPDRS or H&Y score, or medication dosage. Both groups exhibited similar pupillary unrest in darkness.\n\nWe show that melanopsin and the rod/cone-photoreceptor contributions to the pupil control pathway are impaired in people with early-stage Parkinsons disease. Given that the deficits are independent of clinical assessment severity and are observed despite optimal medication, the melanopsin-mediated PIPR may be a biomarker for the detection of Parkinsons disease and its continued monitoring in both medicated and unmedicated individuals.

neuroscience↗

bioRxiv2017

Sorting & Sequencing Flies By Size: Identification Of Novel TOR Regulators And Parameters For Successful Sorting

As DNA sequencing throughput increases, novel strategies for discovering genes that affect traits of interest become available. One strategy starts with a population of animals and selects individuals over multiple generations for a particular trait. Subsequent whole genome sequencing should identify loci affecting this trait. We apply this strategy by sorting flies for wing length over 18 generations, obtaining two populations that differ in wing length by 20%. Flies with longer wings had increased overall body sizes and elevated TOR activity, suggesting that genetic variation targets TOR signaling to influence body size. High-throughput sequencing of big and small flies identified thousands of single nucleotide polymorphisms that differed between the two populations, leading us to identify five novel regulators of TOR signaling. Surprisingly, stochastic simulations of the process show that large fractions of the genetic differences between the big and small flies are probably biological false positives, selected by chance by random drift. We employ these computer simulations to identify experimental setup parameters to improve the signal-to-noise ratio for successfully running sort-and-sequence experiments - a resource which will hopefully be useful for the community.

genetics↗