Dynamic Design of Systems with Semi-rigid Connections Based on Experimental Investigation of the Full Scale Structure

Semi-rigid connections in the construction permit mutual rotation of the nodes. Since such connections are quite common in constructions, especially in the precast ones, it is of interest to determine their dynamic characteristics that is the subject of this proposed paper. During our investigation full scale experiments have been carried out and experimentally determined dynamic characteristics have been compared with those obtained by use of the computational model. The real dynamic characteristics are determined and resonant frequencies of the basic modes in the horizontal and vertical directions, the forms of vibrations at these frequencies, as well as the corresponding coefficient of viscous damping. Testing has been done on the frame structure without facade walls. For the typical precast system "Minoma 1" with span of 12m, "Minoma 2" with span of 20m, and "Minoma 3" with span of 27m, dynamic characteristics: have been determined experimentally by use of forced harmonic excitation, free oscillations and ambient vibration. Experimentally and theoretically obtained values are in a relatively good agreement that is a good starting point for mathematical modeling

The effects of sulfur-containing compounds on redox status in homocysteine-treated rats

© 2019 Polish Pharmaceutical Society. All Rights Reserved. There is growing interest in the activity of sulfur-containing compounds on redox balance in physiological and pathological conditions, considering that some of these compounds have not only antioxidative but also pro-oxidative activities. The aim of this study was to assess possible differences in the effects of various sulfur-containing compounds on redox balance of cardiovascular system in its physiological state and in the early onset of hyperhomocysteinemia. This experimental study divided Wistar albino rats into two groups: Saline-treated (control) and DL-homocysteine-treated (experimental group). Rats from experimental group were subjected to subchronic subcutaneous administration of DL-homocysteine at dose of 0.45 Imol/g body weight twice a day for 2 weeks. At the end of this period, rats were sacrificed, and blood samples were collected to be analyzed for homocysteine concentration and systemic oxidative stress. Isolated rat hearts were excised and attached to the Langendorff apparatus. To assess the effects of acute administration of L-methionine, L-cysteine, N-acetylcysteine, and sodium hydrogen sulfide, the hearts were perfused individually with each of the mentioned substances at the same single dose of 0.5 mmol/L for 5 min. In collected samples of coronary venous effluent oxidative stress biomarkers were determined using spectrophotometry. Total homocysteine level was significantly higher in the experimental group than in the control group, and the effects of applied sulfur-containing compounds were significantly different in experimental and control groups. DL-homocysteine induced considerable changes in the functioning of a cardiovascular system even before an increase in plasma homocysteine values, and action of sulfur-containing compounds varied depending on the presence of homocysteine

The Effects of Potassium Cyanide on the Functional Recovery of Isolated Rat Hearts after Ischemia and Reperfusion: The Role of Oxidative Stress

© 2018 Anica M. Petkovic et al. This investigation is aimed at examining the effects of pharmacological PostC with potassium cyanide (KCN) on functional recovery, gene expression, cytochrome c expression, and redox status of isolated rat hearts. Rats were divided into the control and KCN groups. The hearts of male Wistar albino rats were retrogradely perfused according to the Langendorff technique at a constant perfusion pressure of 70 cmH 2 O. After stabilisation, control hearts were subjected to global ischemia (5 minutes), followed by reperfusion (5 minutes), while experimental hearts underwent global ischemia (5 minutes) followed by 5 minutes of reperfusion with 10 μmol/L KCN. The following parameters of heart function were measured: maximum and minimum rates of pressure development, systolic and diastolic left ventricular pressure, heart rate, and coronary flow. Levels of superoxide anion radical, hydrogen peroxide, nitrites, and index of lipid peroxidation (measured as thiobarbituric acid-reactive substances) were measured in coronary venous effluent, and activity of catalase was determined in heart tissue. Expression of Bax, Bcl-2, SOD-1, SOD-2, and cytochrome c was studied as well. It was shown that expression of Bax, Bcl-2, and SOD-2 genes did not significantly differ between groups, while expression of SOD-1 gene and cytochrome c was lower in the KCN group. Our results demonstrated that KCN improved the recovery of myocardial contractility and systolic and diastolic function, enhanced catalase activity, and diminished generation of prooxidants. However, all possible mechanisms and potential adverse effects of KCN should be further examined in the future

Function of s100 Protein in Coronary Atherosclerosis

Atherosclerosis is a complex disease whose pathogenesis includes endothelial activation, accumulation of lipids in the subendothelium, formation of foam cells, fat bands and formation of atherosclerotic plaque. These complex mechanisms involve different cell populations in the intimate sub-endothelium, and the S-100 protein family plays a role in a number of extracellular and intracellular processes during the development of atherosclerotic lesions. The aim of this study was to determine the phenotypic characteristics of smooth muscle cells and the consequent expression of S100 protein in atherosclerotic altered coronary arteries in advanced stages of atherosclerosis. 19 samples of right atherosclerotic coronary arteries in stages of fibro atheroma (type V lesion) and complicated lesions (type VI lesion) have been analyzed. According to the standard protocol, the following primary antibodies have been used in the immunohistochemical analysis: a-smooth muscle actin (α-SMA), vimentin and S-100 protein. All analyzed samples have been in advanced stages of atherosclerosis, fibro atheroma (stage V lesions) and complicated lesions (type VI lesions). Most of them have had the structure of a complicated lesion with atheroma or fibro atheroma as a basis, subsequently complicated by disruption (subtype VI a), hemorrhage (subtype VI b) or thrombosis (subtype VI c), as well as by the presence of several complications on the same sample. Marked hypocellularity is present in the subendothelium of plaques. Cell population at plaque margins is characterized by immunoreactivity to α-SMA, vimentin, and S100 protein. Some of these cells accumulate lipids and look like foam cells. In the cell population at the margins of the plaques, smooth muscle cells of the synthetic phenotype are present, some of which accumulate lipids and demonstrate S100 immunoreactivity. Summarizing numerous literature data and our results, we could assume that smooth muscle cells, due to their synthetic and proliferative activity in the earlier stages of pathogenesis, as well as the consequent expression of S100 protein, could accumulate lipids in the earlier stages of atherosclerosis which, in advanced stages analyzed in this study, result in immunoreactivity of foam cells of smooth muscle origin to S100 protein

Protective effects of Galium verum L. extract against cardiac ischemia/reperfusion injury in spontaneously hypertensive rats

Copyright © 2019 Jovana Bradic et al. Galium verum L. (G. verum, lady’s bedstraw) is a perennial herbaceous plant, belonging to the Rubiaceae family. It has been widely used throughout history due to multiple therapeutic properties. However, the effects of this plant species on functional recovery of the heart after ischemia have still not been fully clarified. Therefore, the aim of our study was to examine the effects of methanol extract of G. verum on myocardial ischemia/reperfusion (I/R) injury in spontaneously hypertensive rats (SHR), with a special emphasis on the role of oxidative stress. Rats involved in the research were divided randomly into two groups: control (spontaneously hypertensive rats (SHR)) and G. verum group, including SHR rats treated with the G. verum extract (500 mg/kg body weight per os) for 4 weeks. At the end of the treatment, in vivo cardiac function was assessed by echocardiography. Rats were sacrificed and blood samples were taken for spectrophotometric determination of systemic redox state. Hearts from all rats were isolated and retrogradely perfused according to the Langendorff technique. After a stabilization period, hearts were subjected to 20-minute ischemia, followed by 30-minute reperfusion. Levels of prooxidants were spectrophotometrically measured in coronary venous effluent, while antioxidant enzymes activity was assessed in heart tissue. Cell morphology was evaluated by hematoxylin and eosin (HE) staining. 4-week treatment with G. verum extract alleviated left ventricular hypertrophy and considerably improved in vivo cardiac function. Furthermore, G. verum extract preserved cardiac contractility, systolic function, and coronary vasodilatory response after ischemia. Moreover, it alleviated I/R-induced structural damage of the heart. Additionally, G. verum extract led to a drop in the generation of most of the measured prooxidants, thus mitigating cardiac oxidative damage. Promising potential of G. verum in the present study may be a basis for further researches which would fully clarify the mechanisms through which this plant species triggers cardioprotection

Standardized aronia melanocarpa extract as novel supplement against metabolic syndrome: A rat model

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. The aim of our study was to examine the effects of different dietary strategies, high-fat (HFd) or standard diet (Sd) alone or in combination with standardized oral supplementation (0.45 mL/kg/day) of Aronia melanocarpa extract (SAE) in rats with metabolic syndrome (MetS). SAE is an official product of pharmaceutical company Pharmanova (Belgrade, Serbia); however, the procedure for extraction was done by EU-Chem company (Belgrade, Serbia). Rats were divided randomly into six groups: control with Sd, control with Sd and SAE, MetS with HFd, MetS with HFd and SAE, MetS with Sd and MetS with Sd and SAE during 4 weeks. At the end of the 4-week protocol, cardiac function and liver morphology were assessed, while in the blood samples glucose, insulin, iron levels and systemic redox state were determined. Our results demonstrated that SAE had the ability to lower blood pressure and exert benefits on in vivo and ex vivo heart function. Moreover, SAE improved glucose tolerance, attenuated pathological liver alterations and oxidative stress present in MetS. Obtained beneficial effects of SAE were more prominent in combination with changing dietary habits. Promising potential of SAE supplementation alone or in combination with different dietary protocols in triggering cardioprotection should be further examined in future

Melissa officinalis L. as a Nutritional Strategy for Cardioprotection

This review aimed to provide a summary on the traditional uses, phytochemistry, and pharmacological activities in the cardiovascular system and cardiotoxicity of Melissa officinalis (MO), with the special emphasis on the protective mechanisms in different cardiovascular pathologies. MO is a perennial aromatic herb commonly known as lemon balm, honey balm, or bee balm, which belongs to Lamiaceae family. Active components are mainly located in the leaves or essential oil and include volatile compounds, terpenoid (monoterpenes, sesquiterpenes, triterpenes), and polyphenolic compounds [rosmarinic acid (RA), caffeic acid, protocatechuic acid, quercitrin, rhamnocitrin, luteolin]. For centuries, MO has been traditionally used as a remedy for memory, cognition, anxiety, depression, and heart palpitations. Up until now, several beneficial cardiovascular effects of MO, in the form of extracts (aqueous, alcoholic, and hydroalcoholic), essential oil, and isolated compounds, have been confirmed in preclinical animal studies, such as antiarrhythmogenic, negative chronotropic and dromotropic, hypotensive, vasorelaxant, and infarct size–reducing effects. Nonetheless, MO effects on heart palpitations are the only ones confirmed in human subjects. The main mechanisms proposed for the cardiovascular effects of this plant are antioxidant free radical–scavenging properties of MO polyphenols, amelioration of oxidative stress, anti-inflammatory effects, activation of M2 and antagonism of β1 receptors in the heart, blockage of voltage-dependent Ca2+ channels, stimulation of endothelial nitric oxide synthesis, prevention of fibrotic changes, etc. Additionally, the main active ingredient of MO-RA, per se, has shown substantial cardiovascular effects. Because of the vastness of encouraging data from animal studies, this plant, as well as the main ingredient RA, should be considered and investigated further as a tool for cardioprotection and adjuvant therapy in patients suffering from cardiovascular diseases

Predicting severity and intrahospital mortality in CovID-19: The place and role of oxidative stress

SARS-CoV-2 virus causes infection which led to a global pandemic in 2020 with the development of severe acute respiratory syndrome. Therefore, this study was aimed at examining its possible role in predicting severity and intrahospital mortality of COVID-19, alongside with other laboratory and biochemical procedures, clinical signs, symptoms, and comorbidity. This study, approved by the Ethical Committee of Clinical Center Kragujevac, was designed as an observational prospective cross-sectional clinical study which was conducted on 127 patients with diagnosed respiratory COVID-19 viral infection from April to August 2020. The primary goals were to determine the predictors of COVID-19 severity and to determine the predictors of the negative outcome of COVID-19 infection. All patients were divided into three categories: patients with a mild form, moderate form, and severe form of COVID-19 infection. All biochemical and laboratory procedures were done on the first day of the hospital admission. Respiratory (p < 0:001) and heart (p = 0:002) rates at admission were significantly higher in patients with a severe form of COVID-19. From all observed hematological and inflammatory markers, only white blood cell count (9:43 ± 4:62, p = 0:001) and LDH (643:13 ± 313:3, p = 0:002) were significantly higher in the severe COVID-19 group. We have observed that in the severe form of SARS-CoV-2, the levels of superoxide anion radicals were substantially higher than those in two other groups (11:3 ± 5:66, p < 0:001) and the nitric oxide level was significantly lower in patients with the severe disease (2:66 ± 0:45, p < 0:001). Using a linear regression model, TA, anosmia, ageusia, O2-, and the duration at the ICU are estimated as predictors of severity of SARS-CoV-2 disease. The presence of dyspnea and a higher heart rate were confirmed as predictors of a negative, fatal outcome. Results from our study show that presence of hypertension, anosmia, and ageusia, as well as the duration of ICU stay, and serum levels of O2- are predictors of COVID-19 severity, while the presence of dyspnea and an increased heart rate on admission were predictors of COVID-19 mortality

Training/detraining-induced gender specific functional adaptations of isolated rat heart

Background/Aim. Mechanisms responsible for the bene-ficial effects of aerobic exercise training on cardiovascular function are well known, but detraining effects on myo-cardial parameters have not been adequately elucidated. Therefore, the study aimed to determine the occurrence and speed of cardiac adaptation reversibility after the ces-sation of aerobic exercise and to reveal gender differences in achieved effects of training/detraining. Methods. Fe-male and male Wistar albino rats were divided into the fol-lowing groups: Control, trained, and two detrained groups. Hearts were perfused according to the Langendorff tech-nique and the following cardiodynamic parameters were determined: The maximum and minimum rate of pressure development in the left ventricle (dp/dt max and dp/dt min, respectively), systolic and diastolic left ventricular pressure (SLVP and DLVP, respectively), heart rate (HR), and coronary flow. Results. Training significantly reduced values of dp/dt max, dp/dt min, and SLVP in males and females, and coronary flow in males. Detraining caused a reversion of those changes, which was gender-specific. In females, levels of SLVP were higher after 4 weeks of de-training compred to training, and after 2 weeks of detrain-ing. Values of SLVP were lower in both detraining periods compared to training in males. Males had higher coronary flow after 2 weeks of detraining. Simultaneously, coronary flow was reduced in the 4th week of detraining in females. Conclusion. By using a model of the isolated rat heart, the present study confirmed the existence of training-induced changes in cardiac function. Cessation of training was followed by the loss of those adaptations, faster in males than females

Protective Role of Vitamin B<inf>1</inf> in Doxorubicin-Induced Cardiotoxicity in Rats: Focus on Hemodynamic, Redox, and Apoptotic Markers in Heart

Up until now, the specific mechanisms involved in doxorubicin (DOX)-induced cardiotoxicity have not been fully elucidated. Since thiamine deficiency is associated with myocardial dysfunction and it may lead to cardiomyopathy, we aimed to investigate whether thiamine (Vitamin B1) treatment provides cardioprotection and modulates DOX mediated subchronic cardiotoxicity as well as to determine possible mechanisms of its effects. The study involved 48 Wistar albino rats divided into four groups: healthy non-treated rats and healthy rats treated with thiamine and DOX rats without treatment and DOX rats treated with thiamine. DOX was applied as a single i.p.injection (15mg/kg), while thiamine treatment lasted 7days (25mg/kg/dayi.p.). Before and after the treatment hemodynamic changes were monitored in vivo by echocardiography. When the protocol was completed, animals were sacrificed and rat hearts were isolated in order to evaluate parameters of cardiac oxidative stress [superoxide anion radical-O2−, hydrogen peroxide-H2O2, nitric oxide-NO−, index of lipid peroxidation-thiobarbituric acid (TBA) reactive substances (TBARS), superoxide dismutase – SOD, catalase (CAT), and reduced glutathione-GSH] and apoptosis (Bax, Bcl-2, caspases). DOX treatment significantly reduced the ejection fraction, while thiamine treatment led to its minor increase in the DOX-treated group. In that sense, heart oxidative stress markers were significantly increased in DOX-treated rats, while therapeutic dose of thiamine decreased the levels of free radicals. Our study demonstrated the promising ameliorative effects of thiamine against DOX-induced cardiotoxicity through modulation of oxidative stress, suppression of apoptosis, and possibility to improve myocardial performance and morphometric structure of rats` hearts