Postural support requirements preferentially modulate late components of the gastrocnemius response to transcranial magnetic stimulation.

Mounting evidence suggests that motor evoked potentials (MEPs) recorded in upper limb muscles with postural support roles following transcranial magnetic stimulation receive contributions from both corticospinal and non-corticospinal descending pathways. We tested the hypothesis that neural structures responsible for regulating upright balance are involved in transmitting late portions of TMS-induced MEPs in a lower limb muscle. MEPs were recorded in the medial gastrocnemius muscles of each leg, while participants supported their upright posture in five postural conditions that required different levels of support from the target muscles. We observed that early and late portions of the MEP were modulated independently, with early MEP amplitude being reduced when high levels of postural support were required from a target muscle. Independent modulation of early and late MEPs by altered postural demand suggests largely separable transmission of each part of the MEP. The early component of the MEP is likely generated by fast-conducting corticospinal pathways, whereas the later component may be primarily transmitted along a polysynaptic cortico-reticulospinal pathway.

Reliability and Variability of Lower Limb Muscle Activation as Indicators of Familiarity to Submaximal Eccentric Cycling.

Submaximal eccentric (ECC) cycling exercise is commonly used in research studies. No previous study has specified the required time naïve participants take to familiarize with submaximal ECC cycling. Therefore, we designed this study to determine whether critical indicators of cycling reliability and variability stabilize during 15 min of submaximal, semi-recumbent ECC cycling (ECC cycling). Twenty-two participants, aged between 18-51 years, volunteered to complete a single experimental session. Each participant completed three peak eccentric torque protocol (PETP) tests, nine countermovement jumps and 15 min of submaximal (i.e., 10% peak power output produced during the PETP tests) ECC cycling. Muscle activation patterns were recorded from six muscles (rectus femoris, RF; vastus lateralis, VL; vastus medialis, VM; soleus, SOL; medial gastrocnemius, GM; tibialis anterior, TA), during prescribed-intensity ECC cycling, using electromyography (EMG). Minute-to-minute changes in the reliability and variability of EMG patterns were examined using intra-class correlation coefficient (ICC) and variance ratios (VR). Differences between target and actual power output were also used as an indicator of familiarization. Activation patterns for 4/6 muscles (RF, VL, VM and GM) became more consistent over the session, the RF, VL and VM increasing from moderate (ICC = 0.5-0.75) to good (ICC = 0.75-0.9) reliability by the 11th minute of cycling and the GM good reliability from the 1st minute (ICC = 0.79, ICC range = 0.70-0.88). Low variability (VR ≤ 0.40) was maintained for VL, VM and GM from the 8th, 8th and 1st minutes, respectively. We also observed a significant decrease in the difference between actual and target power output (χ2 14 = 30.895, p = 0.006, W = 0.105), expressed primarily between the 2nd and 3rd minute of cycling (Z = -2.677, p = 0.007). Indicators of familiarization during ECC cycling, including deviations from target power output levels and the reliability and variability of muscle activation patterns stabilized within 15 min of cycling. Based upon this data, it would be reasonable for future studies to allocate ∼ 15 min to familiarize naïve participants with a submaximal ECC cycling protocol.

A Semi-recumbent Eccentric Cycle Ergometer Instrumented to Isolate Lower Limb Muscle Contractions to the Appropriate Phase of the Pedal Cycle.

Eccentric (ECC) cycling is used in rehabilitation and sports conditioning settings. We present the construction and mode of operation of a custom-built semi-recumbent ECC cycle designed to limit the production of lower limb muscle activity to the phase of the pedal cycle known to produce ECC contractions. A commercially available semi-recumbent frame and seat (Monarch, 837E Semi-recumbent Bike, Sweden) were used to assemble the ergometer. An electrical drive train system was constructed using individual direct drive servo motors. To avoid active muscle activation occurring during the non-ECC pedaling phase of cycling, a "trip" mechanism was integrated into the drivetrain system using a servo-driven regenerative braking mechanism based on the monitoring of the voltage produced over and above a predetermined threshold produced by the motors. The servo drive internal (DC bus) voltage is recorded and internally monitored during opposing (OPP) and non-opposing (N-OPP) phases of the pedal cycle. To demonstrate that the cycle functions as desired and stops or "trips" when it is supposed to, we present average (of 5 trials) muscle activation patterns of the principal lower limb muscles for regular ECC pedal cycles in comparison with one pedal cycle during which the muscles activated outside the desired phase of the cycle for a sample participant. This semi-recumbent ECC cycle ergometer has the capacity to limit the occurrence of muscle contraction only to the ECC phase of cycling. It can be used to target that mode of muscle contraction more precisely in rehabilitation or training studies.

Defining the Dimensions of Periosteal Free Tissue Transfer Harvest Sites.

Information about the use and donor site morbidity of periosteal free flaps in head and neck reconstruction is limited. The aim of this study was to examine potential periosteal free flap donor sites with respect to their dimensions, tissue and pedicle characteristics, and predicted donor site morbidity in a cadaveric model. The following cadaveric periosteal specimens with a vascular pedicle were harvested using standard surgical approaches: skull, chest wall, sternum, scapula, iliac crest, femur, and humerus. Data relating to the periosteum size and quality, vascular pedicle, surgical factors, feasibility of use, and the potential donor-site morbidity were recorded. One female (age: 78 years, height: 152 cm) and one male (age: 65 years, height: 186 cm) cadaver were used for flap harvest. The skull, chest wall, scapula, and femur were suitable in terms of the size of the periosteum harvested. The procedure to remove the periosteum from the scalp, chest wall, and scapula had the least predicted donor-site morbidity. The pedicle length and vessel caliber from the periosteal flaps were most favorable from the skull, scapula, and iliac crest. Considering all factors, the periosteum harvested from the skull and scapula were the most promising.

Reliability of a Protocol to Elicit Peak Measures Generated by the Lower Limb for Semi-recumbent Eccentric Cycling.

Semi-recumbent eccentric (ECC) cycling is increasingly used in studies of exercise with healthy and clinical populations. However, workloads are generally prescribed using measures obtained during regular concentric cycling. Therefore, the purpose of the study was to quantify the reliability of measures derived from a protocol that elicited peak ECC torque produced by the lower limb in a semi-recumbent position. Experiments were carried out on a dynamometer in a seated, semi-recumbent position identical to that of a custom-built ECC cycle, a modified Monark recumbent cycle. Thirty healthy participants completed two testing sessions. Each session comprised three series of six repetitions of a peak ECC torque protocol (PETP) on an isokinetic dynamometer. Absolute and relative reliability of peak torque, power, angle of peak torque, and work (recorded for each repetition) was determined using coefficient of variation (CV) and intraclass correlation coefficient (ICC), respectively. Ratings of perceived exertion (RPE), muscle soreness, and perceived effort (PE) were recorded pre-PETP, immediately post-PETP, and 1-min post each PETP. The protocol showed absolute reliability values <15% for mean peak (CV = 10.6-12.1) torque, power (CV = 10.4-12.3), angle of peak torque (CV = 1.2-1.4), and work (CV = 9.7-12.1). Moderate to high between-test relative reliability is reported for mean and highest torque (ICC = 0.84-0.95; ICC = 0.88-0.98), power (ICC = 0.84-0.94; ICC = 0.89-0.98), and work (ICC = 0.84-0.93; ICC = 0.88-0.98), respectively. Within-session peak torque, peak power, and peak work showed high relative reliability for mean (ICC = 0.92-0.95) and highest (ICC = 0.92-0.97) values. Overall, the PETP test provides a reliable way of determining peak ECC torque specific to semi-recumbent ECC cycling that may be used to prescribe workloads for this form of exercise.

Randomising stimulus intensity improves the variability and reliability of the assessment of corticospinal excitability.

BACKGROUND: Advances in the control of transcranial magnetic stimulation (TMS) have enabled greater randomisation of stimulus intensity. It is unclear if such randomisation improves assessments of corticospinal excitability. NEW METHOD: We recorded the amplitude of TMS-induced motor evoked potentials (MEPs) from the first dorsal interosseous muscle of eleven participants, during three TMS protocols: blocks of increasing intensity (IB), randomised blocks (RB) and inter-stimulus randomisation (IR). Stimulus intensities from 90 to 140% of active motor threshold described corticospinal input-output (I/O) properties. The experiment was repeated in five participants. RESULTS: Although MEP amplitudes did not differ between IB, RB and IR stimulation protocols, variability was lowest in the IR protocol, compared to IB and RB protocols. Reliability was highest in the IR protocol, compared to IB and IR protocols. COMPARISON WITH EXISTING METHODS: Randomising TMS intensity between each trial produces less variable and more reliable estimates of corticospinal excitability than previously used blocked protocols and produces the same I/O measures. CONCLUSIONS: Inter-trial randomization of TMS intensities appears to be the most reliable method for constructing I/O curves at multiple time points and decreases the variability of responses.

Global Corticospinal Excitability as Assessed in A Non-Exercised Upper Limb Muscle Compared Between Concentric and Eccentric Modes of Leg Cycling.

This study investigated the effects of eccentric (ECC) and concentric (CON) semi-recumbent leg cycling on global corticospinal excitability (CSE), assessed through the activity of a non-exercised hand muscle. Thirteen healthy male adults completed two 30-min bouts of moderate intensity ECC and CON recumbent cycling on separate days. Power output (POutput), heart rate (HR) and cadence were monitored during cycling. Global CSE was assessed using transcranial magnetic stimulation to elicit motor-evoked potentials (MEP) in the right first dorsal interosseous muscle before ('Pre'), interleaved (at 10 and 20 mins, t10 and t20, respectively), immediately after (post, P0), and 30-min post exercise (P30). Participants briefly stopped pedalling (no more than 60 s) while stimulation was applied at the t10 and t20 time-points of cycling. Mean POutput, and rate of perceived exertion (RPE) did not differ between ECC and CON cycling and HR was significantly lower during ECC cycling (P = 0.01). Group mean MEP amplitudes were not significantly different between ECC and CON cycling at P0, t10, t20, and P30 and CON (at P > 0.05). Individual participant ratios of POutput and MEP amplitude showed large variability across the two modes of cycling, as did changes in slope of stimulus-response curves. These results suggest that compared to 'Pre' values, group mean CSE is not significantly affected by low-moderate intensity leg cycling in both modes. However, POutput and CSE show wide inter-participant variability which has implications for individual neural responses to CON and ECC cycling and rates of adaptation to a novel (ECC) mode. The study of CSE should therefore be analysed for each participant individually in relation to relevant physiological variables and account for familiarisation to semi-recumbent ECC leg cycling.

A frame reduction system based on a color structural similarity (CSS) method and Bayer images analysis for capsule endoscopy.

A capsule endoscopy examination of the human small bowel generates a large number of images that have high similarity. In order to reduce the time it takes to review the high similarity images, clinicians will increase the playback speed, typically to 15 frames per second [1]. Associated with this behaviour is an increased probability of overlooking an image that may contain an abnormality. An alternative option to increasing the playback speed is the application of abnormality detection systems to detect abnormalities such as ulcers, tumors, polyps and bleeding. However, applying all of these detection systems requires significant computing time and still produces numerous images with high similarity depending on the specificity of the utilized detection systems. An interesting approach to reduce viewing time is the application of a frame reduction system that reduces the number of images by omitting those with a high similarity of information. The advantage of such a system is that the specialist only needs to review a single image that technically represents a series of images with high similarity. This reduces the total number of images that a specialist must review and importantly, images containing any abnormality are not removed from the review, but simply reduced in number. Thus, the current study developed a frame reduction system using various color models using Bayer images for color texture and a modified local binary pattern (LBP) for structural information. The proposed system achieved a reduction ratio of 93.87%, which is higher than the existing systems and required lesser computation due to the utilization of Bayer images.

The validity of visual acuity assessment using mobile technology devices in the primary care setting.

BACKGROUND: The assessment of visual acuity is indicated in a number of clinical circumstances. It is commonly conducted through the use of a Snellen wall chart. Mobile technology developments and adoption rates by clinicians may potentially provide more convenient methods of assessing visual acuity. Limited data exist on the validity of these devices and applications. OBJECTIVE: The objective of this study was to evaluate the assessment of distance visual acuity using mobile technology devices against the commonly used 3-metre Snellen chart in a primary care setting. METHODS: A prospective quantitative comparative study was conducted at a regional medical practice. The visual acuity of 60 participants was assessed on a Snellen wall chart and two mobile technology devices (iPhone, iPad). RESULTS: Visual acuity intervals were converted to logarithm of minimum angle of resolution (logMAR) scores and subjected to intraclass correlation coefficient (ICC) assessment. The results show a high level of general agreement between testing modality (ICC 0.917 with a 95% confidence interval of 0.887-0.940). DISCUSSION: The high level of agreement of visual acuity results between the Snellen wall chart and both mobile technology devices suggests that clinicians can use this technology with confidence in the primary care setting.

Age-related effects of increasing postural challenge on eye movement onset latencies to visual targets.

When a single light cue is given in the visual field, our eyes orient towards it with an average latency of 200 ms. If a second cue is presented at or around the time of the response to the first, a secondary eye movement occurs that represents a reorientation to the new target. While studies have shown that eye movement latencies to 'single-step' targets may or may not be lengthened with age, secondary eye movements (during 'double-step' displacements) are significantly delayed with increasing age. The aim of this study was to investigate whether the postural challenge posed simply by standing (as opposed to sitting) results in significantly longer eye movement latencies in older adults compared to the young. Ten young (<35 years) and 10 older healthy adults (>65 years) participated in the study. They were required to fixate upon a central target and move their eyes in response to 2 types of stimuli: (1) a single-step perturbation of target position either 15° to the right or left and (2) a double-step target displacement incorporating an initial target jump to the right or left by 15°, followed after 200 ms, by a shift of target position to the opposite side (e.g. +15° then -15°). All target displacement conditions were executed in sit and stand positions with the participant at the same distance from the targets. Eye movements were recorded using electro-oculography. Older adults did not show significantly longer eye movement latencies than the younger adults for single-step target displacements, and postural configuration (stand compared to sit) had no effect upon latencies for either group. We categorised double-step trials into those during which the second light changed after or before the onset of the eye shift to the first light. For the former category, young participants showed faster secondary eye shifts to the second light in the standing position, while the older adults did not. For the latter category of double-step trial, young participants showed no significant difference between sit and stand secondary eye movement latencies, but older adults were significantly longer standing compared to sitting. The older adults were significantly longer than the younger adults across both postural conditions, regardless of when the second light change occurred during the eye shift to the first light. We suggest that older adults require greater time and perhaps attentional processes to execute eye movements to unexpected changes in target position when faced with the need to maintain standing balance.

Of mice, pigs and humans: An analysis of mitochondrial phospholipids from mammals with very different maximal lifespans.

The maximal lifespan (MLS) of mammals is inversely correlated with the peroxidation index, a measure of the proportion and level of unsaturation of polyunsaturated fatty acids (PUFA) in membranes. This relationship is likely related to the fact that PUFA are highly susceptible to damage by peroxidation. Previous comparative work has examined membrane composition at the level of fatty acids, and relatively little is known regarding the distribution of PUFA across phospholipid classes or phospholipid molecules. In addition, data for humans is extremely rare in this area. Here we present the first shotgun lipidomics analysis of mitochondrial membranes and the peroxidation index of skeletal muscle, liver, and brain in three mammals that span the range of mammalian longevity. The species compared were mice (MLS of 4 years), pigs (MLS of 27 years), and humans (MLS of 122 years). Mouse mitochondria contained highly unsaturated PUFA in all phospholipid classes. Human mitochondria had lower PUFA content and a lower degree of unsaturation of PUFA. Pig mitochondria shared characteristics of both mice and humans. We found that membrane susceptibility to peroxidation was primarily determined by a limited number of phospholipid molecules that differed between both tissues and species.

The effect of a familiarisation period on subsequent strength gain.

Untrained subjects can display diverse strength gain following an identical period of resistance exercise. In this investigation, 28 untrained males completed 16-weeks of resistance exercise, comprising 4-weeks familiarisation, and 12-weeks of heavy-load (80-85%) activity. High and low responders were identified by the Δ1RM (Δ one repetition maximum) observed following familiarisation (25.1 ± 1.4%, 9.5 ± 1.4%, P < 0.0001) and differences in electromyographic root mean square amplitude (ΔEMG(RMS) 29.5 ± 8.3%, 2.4 ± 6.0%, P = 0.0140), and habitual and occupational activity patterns were observed between these respective groups. The strength gain (P < 0.0001) observed within high (29.6 ± 1.7%) and low (31.4 ± 2.7%) responding groups was similar during the heavy-load phase, yet ΔEMG(RMS) increased (P = 0.0048) only in low responders (31.5 ± 9.3%). Retrospectively, differences (P < 0.0001) in baseline 1RM strength of high- (19.7 ± 0.9 kg) and low-responding (15.6 ± 0.7 kg) groups were identified, and a strong negative correlation with Δ1RM after 16-weeks (r (2 )= -0.85) was observed. As such, baseline 1RM strength provided a strong predicative measure of strength adaptation. The ΔEMG(RMS) suggests strength variability within high and low responders may be attributed to neural adaptation. However, differences in habitual endurance and occupational physical activity suggests one should consider screening not only recent resistance training, but also other modes of physical activity during participant recruitment.

Factors influencing students' decisions to participate in a short "dissection experience" within a systemic anatomy course.

Changes in medical education have affected both curriculum design and delivery. Many medical schools now use integrated curricula and a systemic approach, with reduced hours of anatomy teaching. While learning anatomy via dissection is invaluable in educational, professional, and personal development, it is time intensive and supports a regional approach to learning anatomy; the use of prosections has replaced dissection as the main teaching method in many medical schools. In our graduate-entry medical degree, we use an integrated curriculum, with prosections to teach anatomy systemically. However, to not exclude dissection completely, and to expose students to its additional and unique benefits, we implemented a short "Dissection Experience" at the beginning of Year 2. Students attended three two-hour anatomy sessions and participated in dissection of the clinically relevant areas of the cubital fossa, femoral triangle, and infraclavicular region. This activity was voluntary and we retrospectively surveyed all students to ascertain factors influencing their decision of whether to participate in this activity, and to obtain feedback from those students who did participate. The main reasons students did not participate were previous dissection experience and time constraints. The reasons most strongly affecting students' decisions to participate related to experience (lack of previous or new) and new skill. Students' responses as to the most beneficial component of the dissection experience were based around practical skills, anatomical education, the learning process, and the body donors. We report here on the benefits and practicalities of including a short dissection experience in a systemic, prosection-based anatomy course.

Review of anatomy education in Australian and New Zealand medical schools.

Anatomy instruction at Australian and New Zealand medical schools has been the subject of considerable debate recently. Many commentators have lamented the gradual devaluation of anatomy as core knowledge in medical courses. To date, much of this debate has been speculative or anecdotal and lacking reliable supporting data. To provide a basis for better understanding and more informed discussion, this study analyses how anatomy is currently taught and assessed in Australian and New Zealand medical schools. A mailed questionnaire survey was sent to each of the 19 Australian and 2 New Zealand medical schools, examining the time allocation, content, delivery and assessment of anatomy for the 2008 academic year. Nineteen of the 21 (90.5%) universities invited to participate completed the survey. There was considerable variability in the time allocation, content, delivery and assessment of anatomy in Australasian medical schools. The average total hours of anatomy teaching for all courses was 171 h (SD +/- 116.7, range 56/560). Historical data indicate a major decline in anatomy teaching hours within medical courses in Australia and New Zealand. Our results reveal that as there is no national curriculum for anatomy instruction, the curriculum content, instruction methodology and assessment is highly variable between individual institutions. Such variability in anatomy teaching and assessment raises an important question: is there also variable depth of understanding of anatomy between graduates of different medical courses?