Behaviour of motor unit action potential rate, estimated from surface EMG, as a measure of muscle activation level

Background  

Surface electromyography (EMG) parameters such as root-mean-square value (RMS) are commonly used to assess the muscle activation level that is imposed by the central nervous system (CNS). However, RMS is influenced not only by motor control aspects, but also by peripheral properties of the muscle and recording setup. To assess motor control separately, the number of motor unit action potentials (MUAPs) per second, or MUAP Rate (MR) is a potentially useful measure. MR is the sum of the firing rates of the contributing MUs and as such reflects the two parameters that the CNS uses for motor control: number of MUs and firing rate.     

Myocardial tissue tagging with cardiovascular magnetic resonance

Aims

Patients with prior major cardiovascular or cerebrovascular events (MACE) are more likely to have future recurrent events independent of traditional cardiovascular disease risk factors. The purpose of this study was to determine if patients with traditional risk factors and prior MACE had increased cardiovascular magnetic resonance (CMR) plaque burden measures compared to patients with risk factors but no prior events.

Methods and Results

Black blood carotid and thoracic aorta images were obtained from 195 patients using a rapid extended coverage turbo spin echo sequence. CMR measures of plaque burden were obtained by tracing lumen and outer vessel wall contours. Patients with prior MACE had significantly higher MR plaque burden (wall thickness, wall area and normalized wall index) in carotids and thoracic aorta compared to those without prior MACE (Wall thickness carotids: 1.03 ± 0.03 vs. 0.93± 0.03, p = 0.001; SD wall thickness carotids: 0.137 ± 0.0008 vs. 0.102 ± 0.0004, p < 0.001; wall thickness aorta: 1.63 ± 0.10 vs. 1.50 ± 0.04, p = 0.009; SD wall thickness aorta: 0.186 ± 0.035 vs. 0.139 ± 0.012, p = 0.009 respectively). Plaque burden (wall thickness) and plaque eccentricity (standard deviation of wall thickness) of carotid arteries were associated with prior MACE after adjustment for age, sex, and traditional risk factors. Area under ROC curve (AUC) for discriminating prior MACE improved by adding plaque eccentricity to models incorporating age, sex, and traditional CVD risk factors as model inputs (AUC = 0.79, p = 0.05).

Conclusion

A greater plaque burden and plaque eccentricity is prevalent among patients with prior MACE.     

Seasonal influenza vaccine delivered by intradermal microinjection: A randomised controlled safety and immunogenicity trial in adults

Influenza vaccines remain largely underused. A promising alternative to current intramuscular vaccines is a trivalent inactivated influenza vaccine (TIV) delivered using a microinjection system to offer a less invasive and possibly more acceptable vaccination. A phase II, multicentre, randomised open-label study in 978 healthy adults (18-57 years) evaluated the immunogenicity and safety of intradermal TIV. Subjects received a 0.1 ml injection of intradermal TIV, containing 9 microg of haemagglutinin (HA) per strain (n = 588) or a conventional 0.5 ml intramuscular vaccine (15 microg of HA/strain; n = 390). Intradermal TIV induced non-inferior humoral immune responses against all three strains and superior responses against both A strains (H1N1, H3N2) compared with the control. Both vaccines were well tolerated.     

Challenges in diagnosing adhesive small bowel obstruction

Adhesive small bowel obstruction(ASBO)is the most frequently encountered surgical disorder of the small intestine.Up to 80%of ASBO cases resolve spontaneously and do not require invasive treatment.It is important to identify such patients that will benefit from conservative treatment in order to prevent unnecessarily exposing them to the risks associated with surgical intervention,such as morbidity and further adhesion formation.For the remaining ASBO patients,timely surgical intervention is necessary to prevent small bowel strangulation,which may cause intestinal ischemia and bowel necrosis.While early identification of these patients is key to decreasing ASBO-related morbidity and mortality,the non-specific signs and laboratory findings upon clinic presentation limit timely diagnosis and implementation of appropriate clinical management.Combining the clinical presentation findings with those from other diagnostic imaging modalities,such as abdominal X-ray,computed tomography-scan and water-soluble contrast studies,will improve diagnosis of ASBO and help clinicians to better evaluate the potential of conservative management as a safe strategy for a particular patient.Nonetheless,patients who present with moderate findings by all these approaches continue to represent a challenge.A new diagnostic strategy is urgently needed to further improve our ability to identify early signs of strangulated bowel,and this diagnostic modality should be able to indicate when surgical management is required.A number of potential serum markers have been proposed for this purpose,including intestinal fatty acid binding protein andα-glutathione S transferase.On-going research is attempting to clearly define their diagnostic utility and to optimize their potential role in determining which patients should be managed surgically.