Skeletal muscle wasting with disuse atrophy is multi-dimensional: the response and interaction of myonuclei, satellite cells and signaling pathways

Maintenance of skeletal muscle is essential for health and survival. There are marked losses of skeletal muscle mass as well as strength and physiological function under conditions of low mechanical load, such as space flight, as well as ground based models such as bed rest, immobilization, disuse, and various animal models. Disuse atrophy is caused by mechanical unloading of muscle and this leads to reduced muscle mass without fiber attrition. Skeletal muscle stem cells (satellite cells) and myonuclei are integrally involved in skeletal muscle responses to environmental changes that induce atrophy. Myonuclear domain size is influenced differently in fast and slow twitch muscle, but also by different models of muscle wasting, a factor that is not yet understood. Although the myonuclear domain is 3-dimensional this is rarely considered. Apoptosis as a mechanism for myonuclear loss with atrophy is controversial, whereas cell death of satellite cells has not been considered. Molecular signals such as myostatin/SMAD pathway, MAFbx, and MuRF1 E3 ligases of the ubiquitin proteasome pathway and IGF1-AKT-mTOR pathway are 3 distinctly different contributors to skeletal muscle protein adaptation to disuse. Molecular signaling pathways activated in muscle fibers by disuse are rarely considered within satellite cells themselves despite similar exposure to unloading or low mechanical load. These molecular pathways interact with each other during atrophy and also when various interventions are applied that could alleviate atrophy. Re-applying mechanical load is an obvious method to restore muscle mass, however how nutrient supplementation (e.g., amino acids) may further enhance recovery (or reduce atrophy despite unloading or ageing) is currently of great interest. Satellite cells are particularly responsive to myostatin and to growth factors. Recently, the hibernating squirrel has been identified as an innovative model to study resistance to atrophy

Prevention of Skeletal Muscle Wasting: Disuse Atrophy and Sarcopenia

First paragraph: Skeletal muscle plays a considerable role in health and disease. Muscle mass is essential for health and survival and plays a major role in mobility as well as morbidity and mortality. There is continual synthesis and degradation of proteins as part of normal metabolism and homeostasis. Equally remarkable, is the characteristic of plasticity allowing muscle to change and adapt depending on the stimuli and load placed upon it

Myostatin levels in skeletal muscle of hibernating ground squirrels

Myostatin, a negative regulator of muscle mass, is elevated during disuse and starvation. Mammalian hibernation presents a unique scenario, where animals are hypocaloric and in torpor, but the extent of muscle protein loss is minimized. We hypothesized that myostatin expression, which is usually increased early in disuse and under hypocaloric conditions, could be suppressed in this unique model. Skeletal muscle was collected from thirteen-lined ground squirrels, Spermophilus tridecemlineatus, at six time points during hibernation: control euthermic (CON); entrance into hibernation (ENT), body temperature (Tb) falling; early hibernation (EHib), stable Tb in torpor for 24 h; late hibernation (LHib), stable Tb in torpor for 3 days; early arousal (EAr), Tb rising; and arousal (AR), Tb restored to 34-37°C for about 18 h. There was no significant increase of myostatin during ENT, EHib or LHib. Unexpectedly, there were approximately sixfold increases in myostatin protein levels as squirrels arose from torpor. The elevation during EAr remained high in AR, which represented an interbout time period. Mechanisms that could release the suppression or promote increased levels of myostatin were assessed. SMAD2 and phosphorylated SMAD2 were increased during EHib, but only the phosphorylated SMAD2 during AR mirrored increases in myostatin. Follistatin, a negative regulator of myostatin, did not follow the same time course as myostatin or its signaling pathway, indicating more control of myostatin at the signaling level. However, SMAD7, an inhibitory SMAD, did not appear to play a significant role during deep hibernation. Hibernation is an excellent natural model to study factors involved in the endogenous intracellular mechanisms controlling myostatin

Die wese van godsdienssin - ’n empiriese studie

In this article the following issues concerning the essence of religiosity are considered: faith, trust, decision making, knowledge of principles, commitment, direction, hope, peace, meaning and security. The respondents used in this study were politicians, businessmen and teacher educators from all sectors and regions of South Africa. Higher order factor analysis and item analysis were used to evaluate the validity and reliability of the questionnaire. Subsequently differential differences were investigated by applying Hotelling's T-square test followed by the Student t-test as well as Multivariate Analysis of Variance (ANOVA) and Scheffe. Significant differences in the degree of religiosity were found between language and religious groups, as well as between respondents with different educational qualifications and between those living in urban and rural areas. Ministers of religion should note that it is essential to guide believers to a greater commitment and to the religious seeking of meaning and peace. The correct knowledge of and insight into the essence of religiosity will lead to attaining this goal

Electrocardiographic features suggestive of a left. ventricular' aneurysm following a high-velocity missile injury

Electrocardiographic features suggestive of a transmural anterior myocardial infarction with resultant left ventricular aneurysm formation were found in a 22-year-old man who had sustained a ballistic missile injury to his chest

Food items consumed by students attending schools in different socio-economic areas in Cape Town, South Africa

Objective: We investigated the food consumption patterns of adolescent students at schools. Our findings are intended to reveal the overall nutritional quality of foods eaten by students at school, including foods brought to school and foods purchased at school. Methods: A questionnaire was completed by 476 students, mostly from grades 7 and 10, from 14 schools in Cape Town, South Africa. The schools were representative of the various ethnic groups and socioeconomic strata of the population. The questionnaire requested information on eating habits at school, foods brought to school and food purchases, and breakfast consumption before school. We also tested whether students knew which foods are healthy and which are less healthy choices. Results: The students were mostly 12 to 16 y of age (mean age 14.5 y). The large majority had breakfast before school (77.8%) and ate at school (79.7%). Food was brought to school by 41% to 56%, whereas 69.3% purchased food at school, mainly at the school store (tuck shop). Predefined “unhealthy” foods brought to school outnumbered “healthy” ones by 2 to 1. Among students who purchased food at school, 70.0% purchased no healthy items, whereas 73.2% purchased two or more unhealthy items. With six foods 84% of students correctly stated whether they were healthy or unhealthy; however, with cola drinks, samoosas (deep-fried pastry with spicy filling), and pies, only 47% to 61% knew that these were less healthy choices. Students’ scores on this question were unrelated to whether they purchased healthy or unhealthy foods. Students who attended schools of high socioeconomic status were twice as likely to bring food to school (64.7% versus 31.0%, P < 0.001), scored higher marks on the quiz of healthy versus unhealthy foods (P < 0.01), but were no more likely to purchase healthy food. Conclusions: The large majority of food eaten by adolescent students in Cape Town is classified as being unhealthy choices. This applies to foods brought to school and food purchases. Consideration needs to be given to policy measures to improve this situation and to improve education of students and their parents

Otitis Media Diagnosis for Developing Countries Using Tympanic Membrane Image-Analysis

AbstractBackgroundOtitis media is one of the most common childhood diseases worldwide, but because of lack of doctors and health personnel in developing countries it is often misdiagnosed or not diagnosed at all. This may lead to serious, and life-threatening complications. There is, thus a need for an automated computer based image-analyzing system that could assist in making accurate otitis media diagnoses anywhere.MethodsA method for automated diagnosis of otitis media is proposed. The method uses image-processing techniques to classify otitis media. The system is trained using high quality pre-assessed images of tympanic membranes, captured by digital video-otoscopes, and classifies undiagnosed images into five otitis media categories based on predefined signs. Several verification tests analyzed the classification capability of the method.FindingsAn accuracy of 80.6% was achieved for images taken with commercial video-otoscopes, while an accuracy of 78.7% was achieved for images captured on-site with a low cost custom-made video-otoscope.InterpretationThe high accuracy of the proposed otitis media classification system compares well with the classification accuracy of general practitioners and pediatricians (~64% to 80%) using traditional otoscopes, and therefore holds promise for the future in making automated diagnosis of otitis media in medically underserved populations

New sepsis definition changes incidence of sepsis in the intensive care unit

Sepsis lacks pathognomonic clinical features and a definitive biochemical or histological diagnostic test. As a result, since 1992, diagnosis of sepsis has been based on the presence of two or more of the criteria characterising the systemic inflammatory response syndrome (SIRS) (Table 1) arising from suspected or proven infection. In response to data questioning this construct, new criteria redefining sepsis, based on the Sequential Organ Failure Assessment (SOFA) score, have been proposed: Sepsis-3 (Table 1). The epidemiological and clinical implications of adopting these new criteria are currently unknown. We aimed to estimate the impact of adopting SOFA-based diagnostic criteria for sepsis on the diagnosis and apparent mortality of sepsis in Australian and New Zealand intensive care units

Mid-pregnancy genetic terminations of pregnancy - postnatal assessment and management

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