Effect of treadmill gait on bone markers and bone mineral density of quadriplegic subjects

Quadriplegic subjects present extensive muscle mass paralysis which is responsible for the dramatic decrease in bone mass, increasing the risk of bone fractures. There has been much effort to find an efficient treatment to prevent or reverse this significant bone loss. We used 21 male subjects, mean age 31.95 ± 8.01 years, with chronic quadriplegia, between C4 and C8, to evaluate the effect of treadmill gait training using neuromuscular electrical stimulation, with 30-50% weight relief, on bone mass, comparing individual dual-energy X-ray absorptiometry responses and biochemical markers of bone metabolism. Subjects were divided into gait (N = 11) and control (N = 10) groups. The gait group underwent gait training for 6 months, twice a week, for 20 min, while the control group did not perform gait. Bone mineral density (BMD) of lumbar spine, femoral neck, trochanteric area, and total femur, and biochemical markers (osteocalcin, bone alkaline phosphatase, pyridinoline, and deoxypyridinoline) were measured at the beginning of the study and 6 months later. In the gait group, 81.8% of the subjects presented a significant increase in bone formation and 66.7% also presented a significant decrease of bone resorption markers, whereas 30% of the controls did not present any change in markers and 20% presented an increase in bone formation. Marker results did not always agree with BMD data. Indeed, many individuals with increased bone formation presented a decrease in BMD. Most individuals in the gait group presented an increase in bone formation markers and a decrease in bone resorption markers, suggesting that gait training, even with 30-50% body weight support, was efficient in improving the bone mass of chronic quadriplegics.

Lead reduces tension development and the myosin ATPase activity of the rat right ventricular myocardium

Lead (Pb2+) poisoning causes hypertension, but little is known regarding its acute effects on cardiac contractility. To evaluate these effects, force was measured in right ventricular strips that were contracting isometrically in 45 male Wistar rats (250-300 g) before and after the addition of increasing concentrations of lead acetate (3, 7, 10, 30, 70, 100, and 300 µM) to the bath. Changes in rate of stimulation (0.1-1.5 Hz), relative potentiation after pauses of 15, 30, and 60 s, effect of Ca2+ concentration (0.62, 1.25, and 2.5 mM), and the effect of isoproterenol (20 ng/mL) were determined before and after the addition of 100 µM Pb2+. Effects on contractile proteins were evaluated after caffeine treatment using tetanic stimulation (10 Hz) and measuring the activity of the myosin ATPase. Pb2+ produced concentration-dependent force reduction, significant at concentrations greater than 30 µM. The force developed in response to increasing rates of stimulation became smaller at 0.5 and 0.8 Hz. Relative potentiation increased after 100 µM Pb2+ treatment. Extracellular Ca2+ increment and isoproterenol administration increased force development but after 100 µM Pb2+ treatment the force was significantly reduced suggesting an effect of the metal on the sarcolemmal Ca2+ influx. Concentration of 100 µM Pb2+ also reduced the peak and plateau force of tetanic contractions and reduced the activity of the myosin ATPase. Results showed that acute Pb2+ administration, although not affecting the sarcoplasmic reticulum activity, produces a concentration-dependent negative inotropic effect and reduces myosin ATPase activity. Results suggest that acute lead administration reduced myocardial contractility by reducing sarcolemmal calcium influx and the myosin ATPase activity. These results also suggest that lead exposure is hazardous and has toxicological consequences affecting cardiac muscle.

Monitoring renal function: measured and estimated glomerular filtration rates - a review

Chronic kidney disease (CKD) is a world-wide public health problem, with adverse outcomes of kidney failure, cardiovascular disease, and premature death. This finding has led to the hypothesis that earlier recognition of kidney disease and successful intervention may improve outcome. The National Kidney Foundation, through its Kidney Disease Outcomes Quality Initiative (K/DOQI), and other National institutions recommend glomerular filtration rate (GFR) for the definition, classification, screening, and monitoring of CKD. Blood creatinine clearance, the most widely used clinical marker of kidney function, is now recognized as an unreliable measure of GFR because serum creatinine is affected by age, weight, muscle mass, race, various medications, and extra-glomerular elimination. Cystatin C concentration is a new and promising marker for kidney dysfunction in both native and transplanted kidneys. Because of its low molecular weight, cystatin C is freely filtered at the glomerulus and is almost completely reabsorbed and catabolized, but not secreted, by tubular cells. Given these characteristics, cystatin C concentration may be superior to creatinine concentration in detecting chronic kidney disease. This review aims to evaluate from recent literature the clinical efficiency and relevance of these GFR markers in terms of screening CKD.

Erythropoietin reduces the expression of myostatin in mdx dystrophic mice

Erythropoietin (EPO) has been well characterized as a renal glycoprotein hormone regulating red blood cell production by inhibiting apoptosis of erythrocyte progenitors in hematopoietic tissues. EPO exerts regulatory effects in cardiac and skeletal muscles. Duchenne muscular dystrophy is a lethal degenerative disorder of skeletal and cardiac muscle. In this study, we tested the possible therapeutic beneficial effect of recombinant EPO (rhEPO) in dystrophic muscles in mdx mice. Total strength was measured using a force transducer coupled to a computer. Gene expression for myostatin, transforming growth factor-β1 (TGF-β1), and tumor necrosis factor-α (TNF-α) was determined by quantitative real time polymerase chain reaction. Myostatin expression was significantly decreased in quadriceps from mdx mice treated with rhEPO (rhEPO=0.60±0.11, control=1.07±0.11). On the other hand, rhEPO had no significant effect on the expression of TGF-β1 (rhEPO=0.95±0.14, control=1.05±0.16) and TNF-α (rhEPO=0.73±0.20, control=1.01±0.09). These results may help to clarify some of the direct actions of EPO on skeletal muscle.

Development and validation of a method for the analysis of tetracyclines in chicken-muscle by liquid chromatography-electrospray-mass spectrometry in tandem (LC-ESI-MS/MS)

A LC-ESI-MS/MS method was developed and validated according to the European Union decision 2002/657/EC, for the determination of tetracyclines (TCs) in chicken-muscle since Europe is one of the main markets for Brazilian products. Linearity of r > 0.9979, limits of quantification in the range of 7.0-35.0 ng/g, average recoveries of 89.38 - 106.27%, within-day and between-day precision were adequate for all TCs. The decision limit and the detection capability were 93.00-106.46 ng/g and 95.84-114.38 ng/g, respectively. This method is suitable for application in surveillance programmes of residues of TCs in chicken-muscle samples.

Simple method for mass production of polypyrrole/carbon nanotubes hybrid artificial muscle

Large scale preparation of hybrid electrical actuators represents an important step for the production of low cost devices. Interfacial polymerization of polypyrrole in the presence of multi-walled carbon nanotubes represents a simple technique in which strong interaction between components is established, providing composite materials with potential applications as actuators due to the synergistic interaction between the individual components, i.e., fast response of carbon nanotubes, high strain of polypyrrole, and diversity in the available geometry of resulting samples.

Aerobic exercise training in heart failure: impact on sympathetic hyperactivity and cardiac and skeletal muscle function

Heart failure is a common endpoint for many forms of cardiovascular disease and a significant cause of morbidity and mortality. Chronic neurohumoral excitation (i.e., sympathetic hyperactivity) has been considered to be a hallmark of heart failure and is associated with a poor prognosis, cardiac dysfunction and remodeling, and skeletal myopathy. Aerobic exercise training is efficient in counteracting sympathetic hyperactivity and its toxic effects on cardiac and skeletal muscles. In this review, we describe the effects of aerobic exercise training on sympathetic hyperactivity, skeletal myopathy, as well as cardiac function and remodeling in human and animal heart failure. We also discuss the mechanisms underlying the effects of aerobic exercise training.

Trypanosoma cruzi and experimental Chagas' disease: characterization of a stock isolated from a patient with associated digestive and cardiac form

A new Trypanosoma cruzi stock isolated from a patient in the chronic phase of Chagas' disease with the digestive and cardiac fortn of the disease was characterized by experimental infection in isogenic, susceptible, A/Sn strain mice. Parasitemia curves showed up to 1.7x10(6) parasites/ml and no mortality was observed up to 300 days post infection. Specific IgM was found in mice in the acute phase up to 40 days and also in the chronic phase. IgG antibodies yvere detected in the acute and chronic phase. Histopathology examination demonstrated myotropism to the digestive tract muscle layers and to the heart.

Influence of physical exercise and sodium intake on arterial pressure and cardiac hypertrophy in rats

Evidence shows that cardiac hypertrophy (CH) is a risk factor for many cardiovascular diseases. Several stimuli may cause CH-like manifestations and promote volume or pressure overload. Exercise-induced cardiac hypertrophy is an expected adaptation to regular exercise training. Salt intake has been shown to be the most important determinant of blood pressure in different populations. The purpose of the present work was to verify the influence of physical exercise and sodium intake on the blood pressure and myocardium. The study was performed on 36 rats divided into six groups: Group I (diet without salt overload), Group II (diet without salt overload and swimming), Group III (diet with 2.5% NaCl solution and swimming), Group IV (diet with 5% NaCl solution and swimming), Group V (diet with 2.5% NaCl solution without exercise), Group VI (diet with 5% NaCl solution without exercise). The arterial pressure was significantly lower in Group I when compared with Group IV. The ratio of cardiac mass/body mass was increased in Groups III and IV. In conclusion, there was evidence that exercise training and NaCl intake promotes arterial hypertension and cardiac hypertrophy.

Assessment of functional capacity through oxygen consumption in patients with asymptomatic probable heart disease

PURPOSE: To compare peak exercise oxygen consumption (VO2peak) of healthy individuals with asymptomatic individuals with probable heart disease. METHODS: Ninety-eight men were evaluated. They were divided into two groups: 1) 39 healthy individuals (group N) with an age range of 50±4.6 years; and 2) 59 asymptomatic individuals with signs of atherosclerotic and/or hypertensive heart disease (group C) with an age range of 51.9±10.4 years. In regard to age, height, body surface area, percentage of fat, lean body mass, and daily physical activity, both groups were statistically similar. Environmental conditions during the ergometric test were also controlled. RESULTS: Maximal aerobic power (watts), VO2peak, maximal heart rate, and maximal pulmonary ventilation were lower in group C (p<0.01) than in group N; weight, however, was lower in group N (p=0.031) than in group C. Differences in the respiratory gas exchange index, heart rate at rest, and the maximal double product of the two groups were not statistically significant. CONCLUSION: Signs of probable heart disease, even though asymptomatic, may reduce the functional capacity, perhaps due to the lower maximal cardiac output and/or muscle metabolic changes.

Analysis of the risk factors for allograft vasculopathy in asymptomatic patients after cardiac transplantation

OBJECTIVE: To study the influence of immune and nonimmune risk factors on the development of allograft vasculopathy after cardiac transplantation. METHODS: We studied 39 patients with a mean age of 46±12 years. The following variables were analyzed: weight (kg), body mass index (kg/m²), donor's age and sex, rejection episodes in the first and second years after transplantation, systolic and diastolic blood pressures (mmHg), total cholesterol and fractions (mg/dL), triglycerides (mg/dL), diabetes, and cytomegalovirus infection. The presence of allograft vasculopathy was established through coronary angiography. RESULTS: Allograft vasculopathy was observed in 15 (38%) patients. No statistically significant difference was observed between the two groups in regard to hypertension, cytomegalovirus infection, diabetes, donor's sex and age, rejection episodes in the first and second years after transplantation, and cholesterol levels. We observed a tendency toward higher levels of triglycerides in the group with disease. Univariate and multivariate analyses showed statistically significant differences between the two groups when we analyzed the body mass index (24.53±4.3 versus 28.11±4.6; p=0.019). CONCLUSION: Body mass index was an important marker of allograft vasculopathy in the population studied.

Distribution of cardiac geometric patterns on echocardiography in essential hypertension. Impact of two criteria of stratification

PURPOSE: To evaluate 2 left ventricular mass index (LVMI) normality criteria for the prevalence of left ventricular geometric patterns in a hypertensive population ( HT ) . METHODS: 544 essential hypertensive patients, were evaluated by echocardiography, and different left ventricular hypertrophy criteria were applied: 1 - classic : men - 134 g/m² and women - 110 g/m² ; 2- obtained from the 95th percentil of LVMI from a normotensive population (NT). RESULTS: The prevalence of 4 left ventricular geometric patterns, respectively for criteria 1 and 2, were: normal geometry - 47.7% and 39.3%; concentric remodelying - 25.4% and 14.3%; concentric hypertrophy - 18.4% and 27.7% and excentric hypertrophy - 8.8% and 16.7%, which confered abnormal geometry to 52.6% and 60.7% of hypertensive. The comparative analysis between NT and normal geometry hypertensive group according to criteria 1, detected significative stuctural differences,"( *p < 0.05):LVMI- 78.4 ± 1.50 vs 85.9 ±0.95 g/m² *; posterior wall thickness -8.5 ± 0.1 vs 8.9 ± 0.05 mm*; left atrium - 33.3 ± 0.41 vs 34.7 ± 0.30 mm *. With criteria 2, significative structural differences between the 2 groups were not observed. CONCLUSION: The use of a reference population based criteria, increased the abnormal left ventricular geometry prevalence in hypertensive patients and seemed more appropriate for left ventricular hypertrophy detection and risk stratification.

Mortality and Embolic Potential of Cardiac Tumors

Background: Cardiac tumors are rare, mostly benign with high embolic potential. Objectives: To correlate the histological type of cardiac masses with their embolic potential, implantation site and long term follow up in patients undergoing surgery. Methods: Between January 1986 and December 2011, we retrospectively analyzed 185 consecutive patients who underwent excision of intracardiac mass (119 females, mean age 48±20 years). In 145 patients, the left atrium was the origin site. 72% were asymptomatic and prior embolization was often observed (19.8%). The diagnosis was established by echocardiography, magnetic resonance and histological examination. Results: Most tumors were located in the left side of the heart. Myxoma was the most common (72.6%), followed by fibromas (6.9%), thrombi (6.4%) and sarcomas (6.4%). Ranging from 0.6cm to 15cm (mean 4.6 ± 2.5cm) 37 (19.8%) patients had prior embolization, stroke 10.2%, coronary 4.8%, peripheral 4.3% 5.4% of hospital death, with a predominance of malignant tumors (40% p < 0.0001). The histological type was a predictor of mortality (rhabdomyomas and sarcomas p = 0.002) and embolic event (sarcoma, lipoma and fibroelastoma p = 0.006), but not recurrence. Tumor size, atrial fibrillation, cavity and valve impairment were not associated with the embolic event. During follow-up (mean 80±63 months), there were 2 deaths (1.1%) and two recurrences 1 and 11 years after the operation, to the same cavity. Conclusion: Most tumors were located in the left side of the heart. The histological type was predictor of death and preoperative embolic event, while the implantation site carries no relation with mortality or to embolic event.

Effects of Growth Hormone on Cardiac Remodeling During Resistance Training in Rats

Abstract Background: Although the beneficial effects of resistance training (RT) on the cardiovascular system are well established, few studies have investigated the effects of the chronic growth hormone (GH) administration on cardiac remodeling during an RT program. Objective: To evaluate the effects of GH on the morphological features of cardiac remodeling and Ca2+ transport gene expression in rats submitted to RT. Methods: Male Wistar rats were divided into 4 groups (n = 7 per group): control (CT), GH, RT and RT with GH (RTGH). The dose of GH was 0.2 IU/kg every other day for 30 days. The RT model used was the vertical jump in water (4 sets of 10 jumps, 3 bouts/wk) for 30 consecutive days. After the experimental period, the following variables were analyzed: final body weight (FBW), left ventricular weight (LVW), LVW/FBW ratio, cardiomyocyte cross-sectional area (CSA), collagen fraction, creatine kinase muscle-brain fraction (CK-MB) and gene expressions of SERCA2a, phospholamban (PLB) and ryanodine (RyR). Results: There was no significant (p > 0.05) difference among groups for FBW, LVW, LVW/FBW ratio, cardiomyocyte CSA, and SERCA2a, PLB and RyR gene expressions. The RT group showed a significant (p < 0.05) increase in collagen fraction compared to the other groups. Additionally, the trained groups (RT and RTGH) had greater CK-MB levels compared to the untrained groups (CT and GH). Conclusion: GH may attenuate the negative effects of RT on cardiac remodeling by counteracting the increased collagen synthesis, without affecting the gene expression that regulates cardiac Ca2+ transport.

Cardiac Remodeling: Concepts, Clinical Impact, Pathophysiological Mechanisms and Pharmacologic Treatment

Abstract Cardiac remodeling is defined as a group of molecular, cellular and interstitial changes that manifest clinically as changes in size, mass, geometry and function of the heart after injury. The process results in poor prognosis because of its association with ventricular dysfunction and malignant arrhythmias. Here, we discuss the concepts and clinical implications of cardiac remodeling, and the pathophysiological role of different factors, including cell death, energy metabolism, oxidative stress, inflammation, collagen, contractile proteins, calcium transport, geometry and neurohormonal activation. Finally, the article describes the pharmacological treatment of cardiac remodeling, which can be divided into three different stages of strategies: consolidated, promising and potential strategies.