Structural properties of lipid reconstructs and lipid composition of normotensive and hypertensive rat vascular smooth muscle cell membranes

Multiple cell membrane alterations have been reported to be the cause of various forms of hypertension. The present study focuses on the lipid portion of the membranes, characterizing the microviscosity of membranes reconstituted with lipids extracted from the aorta and mesenteric arteries of spontaneously hypertensive (SHR) and normotensive control rat strains (WKY and NWR). Membrane-incorporated phospholipid spin labels were used to monitor the bilayer structure at different depths. The packing of lipids extracted from both aorta and mesenteric arteries of normotensive and hypertensive rats was similar. Lipid extract analysis showed similar phospholipid composition for all membranes. However, cholesterol content was lower in SHR arteries than in normotensive animal arteries. These findings contrast with the fact that the SHR aorta is hyporeactive while the SHR mesenteric artery is hyperreactive to vasopressor agents when compared to the vessels of normotensive animal strains. Hence, factors other than microviscosity of bulk lipids contribute to the vascular smooth muscle reactivity and hypertension of SHR. The excess cholesterol in the arteries of normotensive animal strains apparently is not dissolved in bulk lipids and is not directly related to vascular reactivity since it is present in both the aorta and mesenteric arteries. The lower cholesterol concentrations in SHR arteries may in fact result from metabolic differences due to the hypertensive state or to genes that co-segregate with those that determine hypertension during the process of strain selection.

Effect of protein intake on bone and muscle mass in the elderly

The aging process is frequently characterized by an involuntary loss of muscle (sarcopenia) and bone (osteoporosis) mass. Both chronic diseases are associated with decreased metabolic rate, increased risk of falls fracture, and, as a result, increased morbidity and loss of independence in the elderly. The quality and quantity of protein intake affects bone and muscle mass in several ways and there is evidence that increased essential amino acid or protein availability can enhance muscle protein synthesis and anabolism, as well as improve bone homeostasis in older subjects. A thorough evaluation of renal function is important, since renal function decreases with age. Finally, protein and calcium intake should be considered in the prevention or treatment of the chronic diseases osteoporosis and sarcopenia

Augmented muscle vasodilatory responses in obese children with Glu27 beta(2)-adrenoceptor polymorphism

This study examined forearm vasodilatation during mental challenge and exercise in 72 obese children (OC; age = 10 +/- 0.1 years) homozygous with polymorphism in the allele 27 of the beta(2)-adrenoceptors: Gln27 (n = 61) and Glu27 (n = 11). Forearm blood flow was recorded during 3 min of each using the Stroop color-word test (MS) and handgrip isometric exercise. Baseline hemodynamic and vascular measurements were similar. During the MS, peak forearm vascular conductance was significantly greater in group Glu27 (Delta = 0.35 +/- 0.4 vs. 0.12 +/- 0.1 units, respectively, p = .042). Similar results were found during exercise (Delta = 0.64 +/- 0.1 vs. 0.13 +/- 0.1 units, respectively, p = .035). Glu27 OC increased muscle vasodilatory responsiveness upon the MS and exercise.

Creatine supplementation spares muscle glycogen during high intensity intermittent exercise in rats

Background: The effects of creatine (CR) supplementation on glycogen content are still debatable. Thus, due to the current lack of clarity, we investigated the effects of CR supplementation on muscle glycogen content after high intensity intermittent exercise in rats. Methods: First, the animals were submitted to a high intensity intermittent maximal swimming exercise protocol to ensure that CR-supplementation was able to delay fatigue ( experiment 1). Then, the CR-mediated glycogen sparing effect was examined using a high intensity intermittent sub-maximal exercise test ( fixed number of bouts; six bouts of 30-second duration interspersed by two-minute rest interval) ( experiment 2). For both experiments, male Wistar rats were given either CR supplementation or placebo (Pl) for 5 days. Results: As expected, CR-supplemented animals were able to exercise for a significant higher number of bouts than Pl. Experiment 2 revealed a higher gastrocnemius glycogen content for the CR vs. the Pl group (33.59%). Additionally, CR animals presented lower blood lactate concentrations throughout the intermittent exercise bouts compared to Pl. No difference was found between groups in soleus glycogen content. Conclusion: The major finding of this study is that CR supplementation was able to spare muscle glycogen during a high intensity intermittent exercise in rats.

Metabolic syndrome and dietary components are associated with coronary artery disease risk score in free-living adults: a cross-sectional study

Background: Coronary artery disease (CAD) is among the main causes of death in developed countries, and diet and lifestyle can influence CAD incidence. Objective: To evaluate the association of coronary artery disease risk score with dietary, anthropometric and biochemical components in adults clinically selected for a lifestyle modification program. Methods: 362 adults (96 men, 266 women, 53.9 +/- 9.4 years) fulfilled the inclusion criteria by presenting all the required data. The Framingham score was calculated and the IV Brazilian Guideline on Dyslipidemia and Prevention of Atherosclerosis was adopted for classification of the CAD risks. Anthropometric assessments included waist circumference (WC), body fat and calculated BMI (kg/m(2)) and muscle-mass index (MMI kg/m(2)). Dietary intake was estimated through 24 h dietary recall. Fasting blood was used for biochemical analysis. Metabolic Syndrome (MS) was diagnosed using NCEP-ATPIII (2001) criteria. Logistic regression was used to determine the odds of CAD risks according to the altered components of MS, dietary, anthropometric, and biochemical components. Results: For a sample with a BMI 28.5 +/- 5.0 kg/m(2) the association with lower risk (<10% CAD) were lower age (<60 years old), and plasma values of uric acid. The presence of MS within low, intermediary, and high CAD risk categories was 30.8%, 55.5%, and 69.8%, respectively. The independent risk factors associated with CAD risk score was MS and uric acid, and the protective factors were recommended intake of saturated fat and fiber and muscle mass index. Conclusion: Recommended intake of saturated fat and dietary fiber, together with proper muscle mass, are inversely associated with CAD risk score. On the other hand, the presence of MS and high plasma uric acid are associated with CAD risk score.

Eccentric Hip Muscle Function in Females With and Without Patellofemoral Pain Syndrome

Context: Patellofemoral pain syndrome (PFPS) is a common knee condition in athletes. Recently, researchers have indicated that factors proximal to the knee, including hip muscle weakness and motor control impairment, contribute to the development of PFPS. However, no investigators have evaluated eccentric hip muscle function in people with PFPS. Objective: To compare the eccentric hip muscle function between females with PFPS and a female control group. Design: Cross-sectional study. Setting: Musculoskeletal laboratory. Patients or Other Participants: Two groups of females were studied: a group with PFPS (n = 10) and a group with no history of lower extremity injury or surgery (n = 10). Intervention(s): Eccentric torque of the hip musculature was evaluated on an isokinetic dynamometer. Main Outcome Measure(s): Eccentric hip abduction, adduction, and external and internal rotation peak torque were measured and expressed as a percentage of body mass (Nm/kg x 100). We also evaluated eccentric hip adduction to abduction and internal to external rotation torque ratios. The peak torque value of 5 maximal eccentric contractions was used for calculation. Two-tailed, independent-samples t tests were used to compare torque results between groups. Results: Participants with PFPS exhibited much lower eccentric hip abduction (t(18) = -2.917, P = .008) and adduction (t(18) = -2.764, P =.009) peak torque values than did their healthy counterparts. No differences in eccentric hip external (t(18) = 0.45, P = .96) or internal (t(18) = -0.742, P =.47) rotation peak torque values were detected between the groups. The eccentric hip adduction to abduction torque ratio was much higher in the PFPS group than in the control group (t(18) = 2.113, P = .04), but we found no difference in the eccentric hip internal to external rotation torque ratios between the 2 groups (t(18) = -0.932, P = .36). Conclusions: Participants with PFPS demonstrated lower eccentric hip abduction and adduction peak torque and higher eccentric adduction to abduction torque ratios when compared with control participants. Thus, clinicians should consider eccentric hip abduction strengthening exercises when developing rehabilitation programs for females with PFPS.

Selective activation of the rectus abdominis muscle during low-intensity and fatiguing tasks

In order to understand the potential selective activation of the rectus abdominis muscle, we conducted two experiments. In the first, subjects performed two controlled isometric exercises: the curl up (supine trunk raise) and the leg raise (supine bent leg raise) at low intensity (in which only a few motor units are recruited). In the second experiment, subjects performed the same exercises, but they were required to maintain a certain force level in order to induce fatigue. We recorded the electromyographic (EMG) activities of the lower and upper portions of the rectus abdominis muscle during the exercises and used spatial-temporal and frequency analyses to describe muscle activation patterns. At low-intensity contractions, the ratio between the EMG intensities of the upper and lower portions during the curl up exercise was significantly larger than during the leg raise exercise (p = 0.02). A cross-correlation analysis indicated that the signals of the abdominal portions were related to each other and this relation did not differ between the tasks (p = 0.12). In the fatiguing condition, fatigue for the upper portion was higher than for the lower portion during the curl up exercise (p = 0.008). We conclude that different exercises evoked, to a certain degree, individualized activation of each part of the rectus abdominis muscle, but different portions of the rectus abdominis muscle contributed to the same task, acting like a functional unit. These results corroborate the relevance of varying exercise to modify activation patterns of the rectus abdominis muscle.

Chicken skeletal muscle-associated macroarray for gene discovery

Macro- and microarrays are well-established technologies to determine gene functions through repeated measurements of transcript abundance. We constructed a chicken skeletal muscle-associated array based on a muscle-specific EST database, which was used to generate a tissue expression dataset of similar to 4500 chicken genes across 5 adult tissues (skeletal muscle, heart, liver, brain, and skin). Only a small number of ESTs were sufficiently well characterized by BLAST searches to determine their probable cellular functions. Evidence of a particular tissue-characteristic expression can be considered an indication that the transcript is likely to be functionally significant. The skeletal muscle macroarray platform was first used to search for evidence of tissue-specific expression, focusing on the biological function of genes/transcripts, since gene expression profiles generated across tissues were found to be reliable and consistent. Hierarchical clustering analysis revealed consistent clustering among genes assigned to 'developmental growth', such as the ontology genes and germ layers. Accuracy of the expression data was supported by comparing information from known transcripts and tissue from which the transcript was derived with macroarray data. Hybridization assays resulted in consistent tissue expression profile, which will be useful to dissect tissue-regulatory networks and to predict functions of novel genes identified after extensive sequencing of the genomes of model organisms. Screening our skeletal-muscle platform using 5 chicken adult tissues allowed us identifying 43 'tissue-specific' transcripts, and 112 co-expressed uncharacterized transcripts with 62 putative motifs. This platform also represents an important tool for functional investigation of novel genes; to determine expression pattern according to developmental stages; to evaluate differences in muscular growth potential between chicken lines, and to identify tissue-specific genes.

MicroRNA transcriptome profiles during swine skeletal muscle development

Background: MicroRNA (miR) are a class of small RNAs that regulate gene expression by inhibiting translation of protein encoding transcripts. To evaluate the role of miR in skeletal muscle of swine, global microRNA abundance was measured at specific developmental stages including proliferating satellite cells, three stages of fetal growth, day-old neonate, and the adult. Results: Twelve potential novel miR were detected that did not match previously reported sequences. In addition, a number of miR previously reported to be expressed in mammalian muscle were detected, having a variety of abundance patterns through muscle development. Muscle-specific miR-206 was nearly absent in proliferating satellite cells in culture, but was the highest abundant miR at other time points evaluated. In addition, miR-1 was moderately abundant throughout developmental stages with highest abundance in the adult. In contrast, miR-133 was moderately abundant in adult muscle and either not detectable or lowly abundant throughout fetal and neonate development. Changes in abundance of ubiquitously expressed miR were also observed. MiR-432 abundance was highest at the earliest stage of fetal development tested (60 day-old fetus) and decreased throughout development to the adult. Conversely, miR-24 and miR-27 exhibited greatest abundance in proliferating satellite cells and the adult, while abundance of miR-368, miR-376, and miR-423-5p was greatest in the neonate. Conclusion: These data present a complete set of transcriptome profiles to evaluate miR abundance at specific stages of skeletal muscle growth in swine. Identification of these miR provides an initial group of miR that may play a vital role in muscle development and growth.

Aerobic capacity and skeletal muscle function in children with asthma

Background Peripheral muscle strength and endurance are decreased in patients with chronic pulmonary diseases and seem to contribute to patients' exercise intolerance. However, the authors are not aware of any studies evaluating peripheral muscle function in children with asthma. It seems to be implied that children with asthma have lower aerobic fitness, but there are limited studies comparing the aerobic capacity of children with and without asthma. The present study aimed to evaluate muscle strength and endurance in children with persistent asthma and their association with aerobic capacity and inhaled corticosteroid consumption. Methods Forty children with mild persistent asthma (MPA) or severe persistent asthma (SPA) (N=20 each) and 20 children without asthma (control group) were evaluated. Upper (pectoralis and latissimus dorsi) and lower (quadriceps) muscle strength and endurance were assessed, and cardiopulmonary exercise testing was performed. Inhaled corticosteroid consumption during the last 6 and 24 months was also quantified. Results Children with SPA presented a reduction in peak oxygen consumption (VO(2)) (28.2 +/- 8.1 vs 34.7 +/- 6.9 ml/kg/min; p<0.01) and quadriceps endurance (43.1 +/- 6.7 vs 80.9 +/- 11.9 repetitions; p<0.05) compared with the control group, but not the MPA group (31.5 +/- 6.1 ml/kg/min and 56.7 +/- 47.7 repetitions respectively; p>0.05). Maximal upper and lower muscle strength was preserved in children with both mild and severe asthma (p>0.05). Finally, the authors observed that lower muscle endurance weakness was not associated with reductions in either peak VO(2) (r=0.22, p>0.05) or corticosteroid consumption (r=-0.31, p>0.05) in children with asthma. Conclusion The findings suggest that cardiopulmonary exercise and lower limb muscle endurance should be a priority during physical training programs for children with severe asthma.

Differential regulation of PGC-1 alpha expression in rat liver and skeletal muscle in response to voluntary running

Background: The beneficial actions of exercise training on lipid, glucose and energy metabolism and insulin sensitivity appear to be in part mediated by PGC-1 alpha. Previous studies have shown that spontaneously exercised rats show at rest enhanced responsiveness to exogenous insulin, lower plasma insulin levels and increased skeletal muscle insulin sensitivity. This study was initiated to examine the functional interaction between exercise-induced modulation of skeletal muscle and liver PGC-1 alpha protein expression, whole body insulin sensitivity, and circulating FFA levels as a measure of whole body fatty acid (lipid) metabolism. Methods: Two groups of male Wistar rats (2 Mo of age, 188.82 +/- 2.77 g BW) were used in this study. One group consisted of control rats placed in standard laboratory cages. Exercising rats were housed individually in cages equipped with running wheels and allowed to run at their own pace for 5 weeks. At the end of exercise training, insulin sensitivity was evaluated by comparing steady-state plasma glucose (SSPG) concentrations at constant plasma insulin levels attained during the continuous infusion of glucose and insulin to each experimental group. Subsequently, soleus and plantaris muscle and liver samples were collected and quantified for PGC-1 alpha protein expression by Western blotting. Collected blood samples were analyzed for glucose, insulin and FFA concentrations. Results: Rats housed in the exercise wheel cages demonstrated almost linear increases in running activity with advancing time reaching to maximum value around 4 weeks. On an average, the rats ran a mean (Mean +/- SE) of 4.102 +/- 0.747 km/day and consumed significantly more food as compared to sedentary controls (P < 0.001) in order to meet their increased caloric requirement. Mean plasma insulin (P < 0.001) and FFA (P < 0.006) concentrations were lower in the exercise-trained rats as compared to sedentary controls. Mean steady state plasma insulin (SSPI) and glucose (SSPG) concentrations were not significantly different in sedentary control rats as compared to exercise-trained animals. Plantaris PGC-1 alpha protein expression increased significantly from a 1.11 +/- 0.12 in the sedentary rats to 1.74 +/- 0.09 in exercising rats (P < 0.001). However, exercise had no effect on PGC-1 alpha protein content in either soleus muscle or liver tissue. These results indicate that exercise training selectively up regulates the PGC-1 alpha protein expression in high-oxidative fast skeletal muscle type such as plantaris muscle. Conclusion: These data suggest that PGC-1 alpha most likely plays a restricted role in exercise-mediated improvements in insulin resistance (sensitivity) and lowering of circulating FFA levels.

Changes in cardiac heparan sulfate proteoglycan expression and streptozotocin-induced diastolic dysfunction in rats

Background: Changes in the proteoglycans glypican and syndecan-4 have been reported in several pathological conditions, but little is known about their expression in the heart during diabetes. The aim of this study was to investigate in vivo heart function changes and alterations in mRNA expression and protein levels of glypican-1 and syndecan-4 in cardiac and skeletal muscles during streptozotocin (STZ)-induced diabetes. Methods: Diabetes was induced in male Wistar rats by STZ administration. The rats were assigned to one of the following groups: control (sham injection), after 24 hours, 10 days, or 30 days of STZ administration. Echocardiography was performed in the control and STZ 10-day groups. Western and Northern blots were used to quantify protein and mRNA levels in all groups. Immunohistochemistry was performed in the control and 30-day groups to correlate the observed mRNA changes to the protein expression. Results: In vivo cardiac functional analysis performed using echocardiography in the 10-day group showed diastolic dysfunction with alterations in the peak velocity of early (E) diastolic filling and isovolumic relaxation time (IVRT) indices. These functional alterations observed in the STZ 10-day group correlated with the concomitant increase in syndecan-4 and glypican-1 protein expression. Cardiac glypican-1 mRNA and skeletal syndecan-4 mRNA and protein levels increased in the STZ 30-day group. On the other hand, the amount of glypican in skeletal muscle was lower than that in the control group. The same results were obtained from immunohistochemistry analysis. Conclusion: Our data suggest that membrane proteoglycans participate in the sequence of events triggered by diabetes and inflicted on cardiac and skeletal muscles.

Evaluation of muscle strength and motor abilities in children with type II and III spinal muscle atrophy treated with valproic acid

Background: Spinal muscular atrophy (SMA) is an autosomal recessive disorder that affects the motoneurons of the spinal anterior horn, resulting in hypotonia and muscle weakness. The disease is caused by deletion or mutation in the telomeric copy of SMN gene (SMN1) and clinical severity is in part determined by the copy number of the centromeric copy of the SMN gene (SMN2). The SMN2 mRNA lacks exon 7, resulting in a production of lower amounts of the full-length SMN protein. Knowledge of the molecular mechanism of diseases has led to the discovery of drugs capable of increasing SMN protein level through activation of SMN2 gene. One of these drugs is the valproic acid (VPA), a histone deacetylase inhibitor. Methods: Twenty-two patients with type II and III SMA, aged between 2 and 18 years, were treated with VPA and were evaluated five times during a one-year period using the Manual Muscle Test (Medical Research Council scale-MRC), the Hammersmith Functional Motor Scale (HFMS), and the Barthel Index. Results: After 12 months of therapy, the patients did not gain muscle strength. The group of children with SMA type II presented a significant gain in HFMS scores during the treatment. This improvement was not observed in the group of type III patients. The analysis of the HFMS scores during the treatment period in the groups of patients younger and older than 6 years of age did not show any significant result. There was an improvement of the daily activities at the end of the VPA treatment period. Conclusion: Treatment of SMA patients with VPA may be a potential alternative to alleviate the progression of the disease.

Shoulder Muscular Activity During Isometric Three-Point Kneeling Exercise on Stable and Unstable Surfaces

The purpose of this study was to determine if performing isometric 3-point kneeling exercises on a Swiss ball influenced the isometric force output and EMG activities of the shoulder muscles when compared with performing the same exercises on a stable base of support. Twenty healthy adults performed the isometric 3-point kneeling exercises with the hand placed either on a stable surface or on a Swiss ball. Surface EMG was recorded from the posterior deltoid, pectoralis major, biceps brachii, triceps brachii, upper trapezius, and serratus anterior muscles using surface differential electrodes. All EMG data were reported as percentages of the average root mean square (RMS) values obtained in maximum voluntary contractions for each muscle studied. The highest load value was obtained during exercise on a stable surface. A significant increase was observed in the activation of glenohumeral muscles during exercises on a Swiss ball. However, there were no differences in EMG activities of the scapulothoracic muscles. These results suggest that exercises performed on unstable surfaces may provide muscular activity levels similar to those performed on stable surfaces, without the need to apply greater external loads to the musculoskeletal system. Therefore, exercises on unstable surfaces may be useful during the process of tissue regeneration.

Myocardial ultrasonic tissue characterization in patients with thyroid dysfunction

Background: Structural myocardial abnormalities have been extensively documented in hypothyroidism. Experimental studies in animal models have also shown involvement of thyroid hormones in gene expression of myocardial collagen. This study was planned to investigate the ability of ultrasonic tissue characterization, as evaluated by integrated backscatter (IBS), to early identify myocardial involvement in thyroid dysfunction. Patients and Methods: We studied 15 patients with hyperthyroidism (HYPER), 8 patients with hypothyroidism (HYPO), 14 patients with subclinical hypothyroidism (SCH) and 19 normal (N) subjects, who had normal LV systolic function. After treatment, 10 HYPER, 6 HYPO, and 8 SCH patients were reevaluated. IBS images were obtained and analyzed in parasternal short axis (papillary muscle level) view, at left ventricular (LV) posterior wall. The following IBS variables were analyzed: 1) the corrected coefficient (CC) of IBS, obtained by dividing IBS intensity by IBS intensity measured in a rubber phantom, using the same equipment adjustments, at the same depth; 2) cardiac cyclic variation (CV) of IBS - peak-to-peak difference between maximal and minimal values of IBS during cardiac cycle; 3) cardiac cyclic variation index (CVI) of IBS - percentual relationship between the cyclic variation (CV) and the mean value of IBS intensity. Results: CC of IBS was significantly larger (p < 0.05) in HYPER (1.57 +/- 0.6) and HYPO (1.53 +/- 0.3) as compared to SCH (1.32 +/- 0.3) or N (1.15 +/- 0.27). The CV (dB) (HYPO: 7.5 +/- 2.4; SCH: 8.2 +/- 3.1; HYPER: 8.2 +/- 2.0) and the CVI (HYPO: 35.6 +/- 19.7%; SCH: 34.7 +/- 17.5%; HYPER: 37.8 +/- 11.6%) were not significantly different in patients with thyroid dysfunction as compared to N (7.0 +/- 2.0 and 44.5 +/- 15.1%). Conclusions: CC of IBS was able to differentiate cardiac involvement in patients with overt HYPO and HYPER who had normal LV systolic function. These early myocardial structural abnormalities were partially reversed by drug therapy in HYPER group. On the other hand, although mean IBS intensity tended to be slightly larger in patients with SCH as compared to N, this difference was not statistical significant.