Actual temperature during and thermal response after whole-body cryotherapy in cryo-cabin

Whole-body cryotherapy (WBC) involves exposing minimally dressed participants to very cold air (injecting liquid nitrogen with temperature −195 °C), either in a specially designed chamber (cryo-chamber) or cabin (cryo-cabin), for a short period of time. The aim of this study was to examine the actual temperature of the air in the cryo-cabin at different locations throughout the cabin by using human subjects and a manikin. Additionally, we monitored skin temperature before and for 60 min after the cryo-cabin session. Twelve subjects completed one 3 min cryo-cabin session. Temperature next to the skin was assessed during the session, while the skin temperature was monitored before, 3 min after and every 10 min for 60 min after completing the session. There was a statistically significant interaction (time×position) for temperature among the different body parts during the WBC, and for skin temperature among different body parts after the cryo-cabin session. Statistically significant time effects during and following cryo-cabin session were present for all body parts. We showed that actual temperature in the cryo-cabin is substantially different from the one reported by the manufacturer. Thermal response after cryo-cabin session is similar to response observed after cryo-chamber cold exposure reported in previously published studies. This could be of great practical value as cryo-cabins are less expensive and easier to use compared to cryo-chambers.     

Active‐Site Imprinting: Preparation of Fe–N–C Catalysts from Zinc Ion–Templated Ionothermal Nitrogen‐Doped Carbons

Atomically dispersed Fe–N–C catalysts are considered the most promising precious‐metal‐free alternative to state‐of‐the‐art Pt‐based oxygen reduction electrocatalysts for proton‐exchange membrane fuel cells. The exceptional progress in the field of research in the last ≈30 years is currently limited by the moderate active site density that can be obtained. Behind this stands the dilemma of metastability of the desired FeN₄ sites at the high temperatures that are believed to be a requirement for their formation. It is herein shown that Zn²⁺ ions can be utilized in the novel concept of active‐site imprinting based on a pyrolytic template ion reaction throughout the formation of nitrogen‐doped carbons. As obtained atomically dispersed Zn–N–Cs comprising ZnN₄ sites as well as metal‐free N₄ sites can be utilized for the coordination of Fe²⁺ and Fe³⁺ ions to form atomically dispersed Fe–N–C with Fe loadings as high as 3.12 wt%. The Fe–N–Cs are active electocatalysts for the oxygen reduction reaction in acidic media with an onset potential of E₀ = 0.85 V versus RHE in 0.1 m HClO₄. Identical location atomic resolution transmission electron microscopy imaging, as well as in situ electrochemical flow cell coupled to inductively coupled plasma mass spectrometry measurements, is employed to directly prove the concept of the active‐site imprinting approach.     

Dysregulated RNA polyadenylation contributes to metabolic impairment in non-alcoholic fatty liver disease

Pre-mRNA processing is an essential mechanism for the generation of mature mRNA and the regulation of gene expression in eukaryotic cells. While defects in pre-mRNA processing have been implicated in a number of diseases their involvement in metabolic pathologies is still unclear. Here, we show that both alternative splicing and alternative polyadenylation, two major steps in pre-mRNA processing, are significantly altered in non-alcoholic fatty liver disease (NAFLD). Moreover, we find that Serine and Arginine Rich Splicing Factor 10 (SRSF10) binding is enriched adjacent to consensus polyadenylation motifs and its expression is significantly decreased in NAFLD, suggesting a role mediating pre-mRNA dysregulation in this condition. Consistently, inactivation of SRSF10 in mouse and human hepatocytes in vitro, and in mouse liver in vivo, was found to dysregulate polyadenylation of key metabolic genes such as peroxisome proliferator-activated receptor alpha (PPARA) and exacerbate diet-induced metabolic dysfunction. Collectively our work implicates dysregulated pre-mRNA polyadenylation in obesity-induced liver disease and uncovers a novel role for SRSF10 in this process.     

1998 ISEK Congress Keynote Lecture: The use of electromyography in applied physiology

Electromyogram (EMG) analyses (surface, intramuscular and evoked potentials) in studies of muscle function have attracted increasing attention during recent years and have been applied to assess muscle endurance capacity, anaerobic and lactate thresholds, muscle biomechanics, motor learning, neuromuscular relaxation, optimal walking and pedalling speeds, muscle soreness, neuromuscular diseases, motor unit (MU) activities (MU recruitment and rate coding), and skeletal muscle fatigue. This paper deals with the use of EMG analyses employed in the area of applied physiology and is divided into three sections: surface EMG analyses; intramuscular EMG analyses; and evoked potential analyses.     

Listeriolysin O Affects the Permeability of Caco-2 Monolayer in a Pore-Dependent and Ca2+-Independent Manner

Listeria monocytogenes is a food and soil-borne pathogen that secretes a pore-forming toxin listeriolysin O (LLO) as its major virulence factor. We tested the effects of LLO on an intestinal epithelial cell line Caco-2 and compared them to an unrelated pore-forming toxin equinatoxin II (EqtII). Results showed that apical application of both toxins causes a significant drop in transepithelial electrical resistance (TEER), with higher LLO concentrations or prolonged exposure time needed to achieve the same magnitude of response than with EqtII. The drop in TEER was due to pore formation and coincided with rearrangement of claudin-1 within tight junctions and associated actin cytoskeleton; however, no significant increase in permeability to fluorescein or 3 kDa FITC-dextran was observed. Influx of calcium after pore formation affected the magnitude of the drop in TEER. Both toxins exhibit similar effects on epithelium morphology and physiology. Importantly, LLO action upon the membrane is much slower and results in compromised epithelium on a longer time scale at lower concentrations than EqtII. This could favor listerial invasion in hosts resistant to E-cadherin related infection.     

Altered activity of the serratus anterior during unilateral arm elevation in patients with cervical disorders

Altered activity in the axioscapular muscles is considered to be an important feature in patients with neck pain. The activity of the serratus anterior (SA) and trapezius muscles during arm elevation has not been investigated in these patients. The objectives of this study was to investigate whether there is a pattern of altered activity in the SA and trapezius in patients with insidious onset neck pain (IONP) (n = 22) and whiplash associated disorders (WAD) (n = 27). An asymptomatic group was selected for baseline measurements (n = 23).Surface electromyography was used to measure the onset of muscle activation and duration of muscle activity of the SA as well as the upper, middle, and lower trapezius during unilateral arm elevation in the three subject groups. Both arms were tested.With no interaction, the main effect for the onset of muscle activation and duration of muscle activity for serratus anterior was statistically significant among the groups. Post hoc comparison revealed a significantly delayed onset of muscle activation and less duration of muscle activity in the IONP group, and in the WAD group compared to the asymptomatic group. There were no group main effects or interaction effects for upper, middle and lower trapezius.This finding may have implications for scapular stability in these patients because the altered activity in the SA may reflect inconsistent or poorly coordinated muscle activation that may reduce the quality of neuromuscular performance and induce an increased load on the cervical and the thoracic spine.     

Abdominal muscle activation changes if the purpose is to control pelvis motion or thorax motion

The aim of this study was to compare trunk muscular recruitment and lumbar spine kinematics when motion was constrained to either the thorax or the pelvis. Nine healthy women performed four upright standing planar movements (rotations, anterior–posterior translations, medial–lateral translations, and horizontal circles) while constraining pelvis motion and moving the thorax or moving the pelvis while minimizing thorax motion, and four isometric trunk exercises (conventional curl-up, reverse curl-up, cross curl-up, and reverse cross curl-up). Surface EMG (upper and lower rectus abdominis, lateral and medial aspects of external oblique, internal oblique, and latissimus dorsi) and 3D lumbar displacements were recorded. Pelvis movements produced higher EMG amplitudes of the oblique abdominals than thorax motions in most trials, and larger lumbar displacements in the medial–lateral translations and horizontal circles. Conversely, thorax movements produced larger rotational lumbar displacement than pelvis motions during rotations and higher EMG amplitudes for latissimus dorsi during rotations and anterior–posterior translations and for lower rectus abdominis during the crossed curl-ups. Thus, different neuromuscular compartments appear when the objective changes from pelvis to thorax motion. This would suggest that both movement patterns should be considered when planning spine stabilization programs, to optimize exercises for the movement and muscle activations desired.     

Differential activation of parts of the serratus anterior muscle during push-up variations on stable and unstable bases of support

No studies have examined the effects of an unstable surface on push-up and push-up plus exercises in terms of the two parts of the serratus anterior muscle. We hypothesized that the lower part of the serratus anterior would have greater activity with an unstable surface, which requires stabilizing the scapular position. The present study was performed to investigate the intramuscular differences between parts of the serratus anterior muscle during push-up and push-up plus exercises. Twelve healthy subjects were included in the study. The upper and lower parts of the serratus anterior and upper and lower parts of the trapezius were investigated by surface EMG during four types of exercise. Repeated one-way ANOVA was used for statistical analyses. Maintaining the push-up plus phase caused significant increases in EMG activity of the upper serratus anterior compared with the push-up ascending phase on both of stable and unstable bases (P < 0.05). The lower serratus anterior showed increased activation on an unstable surface, which required more joint stability than did the stable base. Upper trapezius/upper serratus anterior ratio was significantly lower in the PUP than in the PUA phase with both stable and unstable bases of support (P < 0.05).Further studies are required to investigate the intramuscular variation in activation of the serratus anterior during exercises for rehabilitation.     

Adaptations in the gait pattern with experimental hamstring pain

Pain changes movement but most studies have focused on basic physiological adaptations during non-functional movement tasks. The existing studies on how pain affects lower extremity gross movement biomechanics have primarily involved movements in which the quadriceps is the primary muscle and little attention has been given to how pain in other muscles affects functional movement. The purpose of this study was to investigate the changes in the gait patterns of healthy subjects that occur during experimental muscle pain in the biceps femoris.In a cross-over study design, 14 healthy volunteers underwent EMG assisted 3D gait analyses before, during and after experimental biceps femoris pain induced by intramuscular injections of hypertonic saline. Isotonic saline injections were administered as a non-painful control.The experimental biceps femoris pain led to reductions in hip extensor moments, knee flexor and lateral rotator moments. No changes in lower extremity kinematics and EMG activity in any of the recorded muscles were observed.It is concluded that experimental muscle pain in the biceps femoris leads to changes in the gait pattern in agreement with unloading of the painful muscle. The changes are specific to the painful muscle. The present study provides support to the theory that musculoskeletal pain is a protective signal leading to changes in movement patterns that serve to unload the painful tissue.     

Associations between the masticatory system and muscle activity of other body districts. A meta-analysis of surface electromyography studies

The aim of this meta-analysis regarding the use of surface electromyography (sEMG) is to assess the scientific evidence for detectable correlations between the masticatory system and muscle activity of the other body districts, particularly those mainly responsible for body posture. A literature survey was performed using the PubMed database, covering the period from January 1966 to April 2011, and choosing medical subject headings. After selection, five articles qualified for the final analysis. One study article was judged to be of medium quality, the remaining four of low quality. No study included a control group or follow-up; in only one study, subjects with impairment of the masticatory system were enrolled. In all studies, detectable correlations between the masticatory systems and muscle activity of the other body districts, or vice versa, were found; however, after a reappraisal of the data provided in these studies, only weak correlations were found, which reached biological, but not clinical relevance. With the limitations that arise from the poor methodological quality of the published study reports discussed here, the conclusion is that a correlation between the masticatory system and muscle activity of the other body districts might be detected through sEMG under experimental conditions; however, this correlation has little clinical relevance. While more investigations with improved levels of scientific evidence are needed, the current evidence does not support clinically relevant correlations between the masticatory system and the muscle activity of other body districts, including those responsible for body posture.