Loss Of Myofibrils Research Articles

Immunohistochemical and ultrastructural analysis of sporadic inclusion body myositis: a case series

Sporadic inclusion body myositis (s-IBM) is a progressive, skeletal muscle disease with poor prognosis. However, establishing the final diagnosis is difficult because of the lack of clear biomarkers in the blood serum and very slow development of clinical symptoms. Moreover, most other organs function normally without any disturbance. Here, in patients with this untreatable disease, we have underlined the importance of immunohistochemical and ultrastructural assessment of skeletal muscle in patients diagnosed with s-IBM. The goal of this study was to identify the distribution of specific antigens and to determine morphological features in order to localize pathological protein aggregates, rimmed vacuoles, and loss of myofibrils, which are key elements in the diagnosis of s-IBM. All studied patients were between 48 and 83 years of age and were hospitalized in the Department of Rheumatology and Internal Medicine between 2011 and 2016. Anamneses revealed an accelerated progression of muscle atrophy, weakness of limb muscles, and difficulties with climbing stairs. Based on histopathology and transmission electron microscopy examination, inflammatory infiltrations consisting of mononuclear cells, severe atrophy and focal necrosis of myofibers, splitting of myofilaments, myelinoid bodies and rimmed vacuoles were observed. Primary antibodies directed against CD3, CD8, CD68, cN1A, beta-amyloid, Tau protein and apolipoprotein B made it possible to identify types of cells within infiltrations as well as the protein deposits within myofibers. Using a combination of immunohistochemistry and electron microscopy methods, we were able to establish the correct final diagnosis and to implement a specific treatment to inhibit disease progression.

GSK3-β promotes calpain-1–mediated desmin filament depolymerization and myofibril loss in atrophy

Myofibril breakdown is a fundamental cause of muscle wasting and inevitable sequel of aging and disease. We demonstrated that myofibril loss requires depolymerization of the desmin cytoskeleton, which is activated by phosphorylation. Here, we developed a mass spectrometry-based kinase-trap assay and identified glycogen synthase kinase 3-β (GSK3-β) as responsible for desmin phosphorylation. GSK3-β inhibition in mice prevented desmin phosphorylation and depolymerization and blocked atrophy upon fasting or denervation. Desmin was phosphorylated by GSK3-β 3 d after denervation, but depolymerized only 4 d later when cytosolic Ca2+ levels rose. Mass spectrometry analysis identified GSK3-β and the Ca2+-specific protease, calpain-1, bound to desmin and catalyzing its disassembly. Consistently, calpain-1 down-regulation prevented loss of phosphorylated desmin and blocked atrophy. Thus, phosphorylation of desmin filaments by GSK3-β is a key molecular event required for calpain-1-mediated depolymerization, and the subsequent myofibril destruction. Consequently, GSK3-β represents a novel drug target to prevent myofibril breakdown and atrophy.

Trypanosoma evansi: ultrastructural cardiac muscle and cardiac microvasculature changes in experimental murine infections

Background: Trypanosoma evansi is the etiologic agent of the equine trypanosomosis, a disease related to the detriment of the extensive bovine farming in the Venezuelan grasslands. Even though macroscopic pathologies such as anemia, pale mucosa, icteric tissues, generalized edema, splenomegaly, liver and renal hypertrophy, abortion, anoestrus, emaciation, lymphadenopathies, striated muscle atrophy as well as epicardiac and endocardiac hemorrhages have been described for infections with the agent, no reports of any heart ultrastructural change in experimental or natural infections induced by Venezuelan T. evansi isolates are available. So, a transmission electron microscopic approach to the problem was needed. This work describes cell features of the cardiac myocyte and the cardiac microvasculature ultrastructure in mice experimentally infected with an equine local isolate of T. evansi, also providing an account of the infection with the mice’s survival. Materials, Methods & Results: NMRI Mus musculus were inoculated with a Venezuelan T. evansi isolate derived from a naturally infected Equus caballus. From day three post-infection, and every other day until the mice’s death, one rodent was randomly killed, the heart apex was isosmotically removed and cut in symmetrical blocks, which were fixed, post-fixed, dehydrated, infiltrated, included, sectioned, contrasted and studied by means of transmission electron microscopy, with the subsequent characterization of the cardiac myocyte and the cardiac microvasculature transformations. The evaluation of the micrographs demonstrated ultrastructural time-increasing harmful mitochondrial alterations that included reduction in the number of mitochondria per cell, decrease in mitochondrial dimensions and lessening of the number of cristae per mitochondrion. Myofibrillar destruction, myofilament loss and atrophy were also evident. In addition, damaging augmentation of the vascular endothelium thickness, appearance of abnormal endothelial projections and caveolae loss were incontestable changes. The presence of trypanosomes in the lumen of the heart capillary system was indubitable; however, neither intra-endothelial nor intra-cardiac myocyte parasites were observed; no inter-tissular parasites were found either. Discussion: The ultrastructural modifications in the muscular heart tissue and in the heart capillaries of experimentally infected mice with a Venezuelan isolate of T. evansi, derived from a feral domesticated E. caballus, were incontrovertible being characterized by the deleterious gradual mitochondrial decline. In such a context, the close relationship between the mitochondrion and the ribosome disposition is related to protein synthesis being associated to diverse functions and stress reactions to non-proper substances like T. evansi, such circumstance could lead to cardiac myocyte mitochondrial deterioration. Additionally, changes in the mitochondrial dimensions and/or the number of cristae/mitochondrion are related to the mitochondrial enzyme activity. The myofilament loss and the myofibrillar destruction reported in this work could derive from the capillary damage per se. The overexpression of serum deprivation protein response induces caveolae deformation and endothelial cell membrane tubulation. The heart’s myodamage could be additionally caused by autoimmunity and/or electrolytic unbalance induced by the trypanosome. The endothelial cell detriment could be the result of a distant effect of parasitic toxic catabolites, intense edema, hypoxia and/or ischemia. The atrophy was put in evidence by a growing volume reduction as a result of myofibril loss probably due to collateral ischemic and hypoxic mechanisms caused by the parasite. Furthermore, the effect due to toxins could cause intramuscular microvasculature damage, hypoxia and fibrillar atrophy.The trypanosomes were present in the cardiac capillary circulation, being able, as an inducible result of the liberation of active materials, to provoke mononuclear and polymorphonuclear infiltration, contributing to the inflammatory response.The subcellular damage in the cardiac myocites and in the cardiac microvascularure, along with the presence of trypanosomes in the coronary circulation, and the lack of association between parasites and cardiac myocites or parasites and cardiac endothelial cells, are attributes with a remarkable pathological meaning since it represents a non described phenomenon of gradual ultrastructural change that take part of the events, resulting in the murine host death through a degenerative mechanism.

Protective and therapeutic effects of dexpanthenol on isoproterenol-induced cardiac damage in rats.

The purpose of the study was to explore the protective and therapeutic effects of dexpanthenol (DEX) on isoproterenol (ISO)-induced cardiac damage. Forty rats were distributed into four groups: group I (Control); group II (ISO); ISO (150 mg/kg/day) was given to rats once a day for 2 consecutive days with an interval of 24 h; group III (DEX+ISO): DEX (250 mg/kg) was applied 30 min before the first ISO administration and continued in the next two days after second ISO administration; group IV (ISO+DEX): After the ISO treatment at 1st and 2nd days, DEX was given at 3rd and 4th days. Rats were monitored for mean arterial blood pressure (BP), heart rate, oxygen saturation (%SO2 ), and electrocardiography (ECG). Heart tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), reduced glutathione (GSH), total oxidant status (TOS); total antioxidant capacity (TAC), oxidative stress index (OSI), and caspase-3 were determined. BP and SO2 values indicated a significant decrease in the ISO group. Also, T wave negativity was observed in 6 of 10 rats, SOD, CAT, and GPX levels were significantly lower in ISO group than control group. ISO administration increased TOS and OSI levels, whereas DEX treatment significantly reduced these parameters. Also, ISO-induced morphological alterations such as disorganization of cardiomyocytes, loss of myofibrils and cytoplasmic vacuolization whereas these histological damages were significantly decreased in ISO+DEX and DEX+ISO groups when compared to the ISO group. This study implies the cardioprotective effects of DEX on ISO-induced cardiotoxicity.

High doses of S-methylcysteine cause hypoxia-induced cardiomyocyte apoptosis accompanied by engulfment of mitochondaria by nucleus

Despite its important role as a medicinal plant, some studies reported a toxic effect for garlic (Allium sativum) when given in higher doses. Herein, we investigated the possible cardiotoxic effects of high doses of S-methylcysteine (SMC), a water soluble organosulfur compound present in garlic. Rats were orally administered SMC at a low dose (50mg), high dose (150mg) and very high dose (300mg)/kg body weight, or saline (control) for 10days. High and very high doses of SMC resulted in a significant increase in serum cardiac injury biomarkers [aspartate transaminase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) and cardiac troponin T (cTnT)], as well as oxidative stress marker nitric oxide (NO) concentration in heart and a significant decrease in cardiac superoxide dismutase (SOD) activity. Moreover, ultrastructure findings in myocardium of rats treated by high and very high doses showed inter-bundle vacuolation, loss of myofibrils, and centripetal movement of mitochondria towards nucleus. The mitochondria were partially surrounded by nuclear membrane at high dose SMC, and completely engulfed by nucleus at very high dose. This centripetal movement of mitochondria accompanied by cardiomyocytes hypoxia-induced apoptosis as evident by increasing TUNEL positive cells as well as upregulation of apoptotic genes (caspase3 and Bax), hypoxia inducible factor 1 alpha (HIF1α), dynein light chain 1 (DYNLL1) and downregulation of the anti-apoptotic marker, Bcl2. We conclude that high and very high doses of SMC cause hypoxia induced cardiomyocyte apoptosis accompanied by engulfment of mitochondria by nucleus.

Abstract 229: Searching Genetic Modifiers For bag3 -based Cardiomyopathy Using Adult Zebrafish Models

We recently developed a forward mutagenesis screening strategy in adult zebrafish to screen gene-breaking transposon (GBT) mutants, and identified four genetic modifiers for doxorubicin-induced cardiomyopathy. However, it remains unclear whether these genetic modifiers identified from an acquired cardiomyopathy model exert similar modifying effects on inherited cardiomyopathy models. To address this question, we generated BCL2-associated athanogene 3 (bag3) gene knockout in adult zebrafish, using the transcription activator-like effector nucleases (TALEN) genome editing technology. In the bag3-/- fish, progressive cardiac phenotypes reminiscent of human cardiomyopathy such as fetal gene activation, myofibril loss and cardiac dysfunction were detected. At the single myofibril level, reduced active contractility was observed, supporting the dilated cardiomyopathy (DCM)-like phenotype. Based on the ejection fraction index quantified using a newly developed ex vivo assay, different pathogenesis stages including pre-DCM, early-DCM and late DCM were defined. Next, we assessed the potential modifying effects of the four DIC-modifying mutants on bag3 -based cardiomyopathy model. Different from the other three GBT mutants, GBT0411+/- , which tags the long isoform of dnajb6 b gene, dramatically accelerated the cardiac dysfunction and fish mortality in the bag3-/- fish, suggesting dnajb6b as a sensitive genetic modifier for bag3-based cardiomyopathy. Mechanistically, we showed that Bag3 physically interacts with Dnajb6, and we hypothesize that impaired autophagy and/or endoplasmic reticulum stress convey the synergistic cardiac dysfunction and fish mortality phenotypes in the GBT0411+/-;bag3-/- double mutants. In summary, this study demonstrates that an inherited cardiomyopathy model can be established in an adult zebrafish, which can be utilized to search genetic modifiers. Future studies employing this simple vertebrate model amenable to forward mutagenesis screening promise systematic identification of genetic modifiers for different types of cardiomyopathies, a foundation for individualized medicine.

Morphometric features of cardiomyocytes in the ventricular septum of patients with hypertrophic cardiomyopathy

to determine the diameter and length of cardiomyocytes (CMC) in the ventricular septum (VS) of patients with hypertrophic cardiomyopathy (HCM) and to analyze correlations of a change in CMC sizes with the anatomical features of the heart in the patients. Longitudinal sections of intraoperative myocardial biopsy specimens taken from 23 patients aged 15-59 years with HCM were treated using immunohistochemical detection of connexin 43; the sizes of 50 CMCs were measured; a 4-point scale was used to assess the degree of myofibril loss (MFL) in these cells. The change in the diameter and length of the cells during their rearrangement as MFL gradually increased, as well as the correlations of CMC sizes with the anatomical parameters of the heart were analyzed. VS CMCs from the patients with HCM were hypertrophic and were in the early stages of rearrangement accompanied by MFL. During this rearrangement, CMCs in some patients grew in length and, less frequently, diameter. The average diameter of CMCs was directly correlated with VS thickness. The average length of the cells in the CMC population with a considerable degree of MFL also directly correlated with VS thickness. The findings could suggest that the factor raising VS thickness in HCM may be an increase in not only diameter of CMCs, but also in length of CMCs, which had impaired orientation in the VS - which are oriented perpendicular to their normal tangential position. The presence of such CMCs in the VS myocardium in patients with HCM can be discussed due to the typical large number of myocardial areas with the impaired parallel arrangement of CMCs.

Activation of the Nkx2.5-Calr-p53 signaling pathway by hyperglycemia induces cardiac remodeling and dysfunction in adult zebrafish.

ABSTRACTHyperglycemia is an independent risk factor for diabetic cardiomyopathy in humans; however, the underlying mechanisms have not been thoroughly elucidated. Zebrafish (Danio rerio) was used in this study as a novel vertebrate model to explore the signaling pathways of human adult cardiomyopathy. Hyperglycemia was induced by alternately immersing adult zebrafish in a glucose solution or water. The hyperglycemic fish gradually exhibited some hallmarks of cardiomyopathy such as myocardial hypertrophy and apoptosis, myofibril loss, fetal gene reactivation, and severe arrhythmia. Echocardiography of the glucose-treated fish demonstrated diastolic dysfunction at an early stage and systolic dysfunction at a later stage, consistent with what is observed in diabetic patients. Enlarged hearts with decreased myocardial density, accompanied by decompensated cardiac function, indicated that apoptosis was critical in the pathological process. Significant upregulation of the expression of Nkx2.5 and its downstream targets calreticulin (Calr) and p53 was noted in the glucose-treated fish. High-glucose stimulation in vitro evoked marked apoptosis of primary cardiomyocytes, which was rescued by the p53 inhibitor pifithrin-μ. In vitro experiments were performed using compound treatment and genetically via cell infection. Genetically, knockout of Nkx2.5 induced decreased expression of Nkx2.5, Calr and p53. Upregulation of Calr resulted in increased p53 expression, whereas the level of Nkx2.5 remained unchanged. An adult zebrafish model of hyperglycemia-induced cardiomyopathy was successfully established. Hyperglycemia-induced myocardial apoptosis was mediated, at least in part, by activation of the Nkx2.5–Calr–p53 pathway in vivo, resulting in cardiac dysfunction and hyperglycemia-induced cardiomyopathy.

Morphological features of the myocardium of the atrial appendages in patients with different forms of atrial fibrillation

to analyze the morphological features of the myocardium of the atrial appendages in patients with different forms of atrial fibrillation (AF) and to compare the findings with the clinical parameters of patients. Light and electron microscopies were used to examine the myocardium of the atrial appendages in adult patients with paroxysmal (PAF), persistent (PrAF), or long-standing persistent atrial fibrillation (LPAF) and in comparison group patients with sinus rhythm without history of AF. A morphometric method was employed to evaluate myocardial fibrosis and to measure the diameter of cardiomyocytes (CMCs); the degree of lipomatosis and amyloidosis was semiquantitatively determined; and the content of CMC myofibrils was estimated. Atrial natriuretic peptide content in the myocytes was measured by immunoconfocal microscopy. In all groups, the patients with AF were found to have signs of atrial structural remodeling: fibrosis, lipomatosis, isolated atrial amyloidosis, CMC hypertrophy with the phenomena of a partial loss of myofibrils without significant differences between these parameters in different groups. In PAF patients, atrial remodeling was accompanied by hypertrophy of a number of CMCs with their higher myofibrilar mass; the increased CMC size in the left atrial appendage prevented left atrial enlargement; the degree of amyloidosis negatively correlated with the CMC myofibrillar loss that was recorded in the minor CMCs; the degree of CMC myolysis positively correlated with mitral valve insufficiency and left atrial enlargement. In contrast to the clinical and morphological changes that are typical of PAF, in LPAF the increase in CMC sizes was positively correlated with left atrial enlargement and mitral annular dilatation; while the myofibrillar loss phenomenon was noted in the most hypertrophied CMCs; the degree of amyloidosis was positively correlated with CMC myofibrillar loss. In the patients with PrAF, the size of CMCs did not correlate with their myofibril content. The patients with PAF were ascertained to have opposite changes in the ratio of CMC hypertrophy to left atrial enlargement, amyloidosis, and CMC myofibrillar loss, hypertrophy of CMCs and their myofibril content in comparison with these indicators in LPAF.

Dietaryl‐carnitine prevents histopathological changes in tilapia (Oreochromis Niloticus) exposed to cylindrospermopsin

Cylindrospermopsin (CYN) is a cytotoxin highly water-soluble, which is easily taken up by several aquatic organisms. CYN acts as a potent protein and glutathione synthesis inhibitor, as well as inducing genotoxicity, oxidative stress, and histopathological alterations. This is the first study reporting the protective effect of a l-carnitine (LC) pretreatment (400 or 880 mg LC/kg bw fish/day, for 21 days) on the histopathological alterations induced by pure CYN or Aphanizomenon ovalisporum lyophilized cells (400 µg CYN/kg bw fish) in liver, kidney, heart, intestines, and gills of tilapia (Oreochromis niloticus) acutely exposed to the toxin by oral route. The main histopathological changes induced by CYN were disorganized parenchyma with presence of glycogen and lipids in the cytoplasm (liver), glomerulonephritis, glomerular atrophy, and dilatation of Bowman's capsule (kidney), myofibrolysis, loss of myofibrils, with edema and hemorrhage (heart), intestinal villi with necrotic enterocytes and partial loss of microvilli (gastrointestinal tract), and hyperemia and hemorrhage (gills). LC pretreatment was able to totally prevent those CYN-induced alterations from 400 mg LC/kg bw fish/day in almost all organs, except in the heart, where 880 mg LC/kg bw fish/day were needed. In addition, the morphometric study indicated that LC managed to recover totally the affectation in the cross sections of the proximal and distal convoluted tubules in CYN-exposed fish. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 241-254, 2017.

The effect of quercetin on cyclosporine-A-induced cardiotoxicity in adult male albino rats

Background Cyclosporine-A (Cs-A) is the most widely used immunosuppressive agent in organ transplantation and autoimmune disease treatment. Nevertheless, its therapeutic use is associated with serious effects, including cardiotoxicity. Quercetin is one of the naturally occurring flavonoids present in a lot of the human diets. Objective The aim of this study was to evaluate the effect of quercetin on cyclosporine-induced cardiotoxicity in adult male albino rats. Materials and methods Forty adult male rats were included and divided into four groups (10 rats each): group I was the control group; group II (the quercetin group) rats received daily intraperitoneal injection of quercetin (15 mg/kg body weight/day) for 4 weeks; group III (the cyclosporine group) rats received daily subcutaneous injection of Cs-A (20 mg/kg body weight/day) for 4 weeks; and group IV (the cyclosporine and quercetin group) rats received Cs-A and quercetin for 4 weeks. Heart specimens were taken and processed for light microscopy study (H&E and Masson’s trichrome staining and immunohistochemical staining for caspase-3) and electron microscopy study. Results Group III showed prominent myocardial fiber degeneration with areas of myofibril loss and interstitial hemorrhage. This was supported by the positive reaction for apoptotic marker caspase-3. An increase in the collagen fibers in the endomysium was obvious. Electron microscopic results showed irregular nucleus with disruption of the sarcolemma and intercalated discs. The cytoplasm showed an area of myofibril loss and mitochondrial swelling. Group IV showed improvement in most light and electron microscope changes described before. Conclusion Quercetin can be a natural cardioprotective agent and can be used to improve cyclosporine-induced cardiotoxicity, as it has antioxidant and anti-inflammatory enzyme activities. We advise taking a diet rich in quercetin or dietary supplementation.

Ultrastructural changes associated with myocardial apoptosis, in failing rat hearts induced by volume overload

BackgroundMyocardial apoptosis has been discussed to play a pivotal role in the development and progression of congestive heart failure (CHF). However, recently there is doubt on the evidence of myocardial apoptosis in heart failure as information on ultrastructural changes by electron microscopy is still scarce. This project therefore aimed to detect direct morphological evidence of myocardial apoptosis in an experimental heart failure model. MethodFollowing IRB approval, an aortocaval fistula (ACF) was induced in male Wistar rats using a 16G needle. 28±2days following ACF rats were examined by hemodynamic measurements, Western blot, immunofluorescence confocal and electron microscopic analysis. ResultsWithin 28±2days of ACF heart (3.8±0.1 vs. 6.6±0.3mg/g) and lung (3.7±0.2 vs. 6.9±0.5mg/g) weight indices significantly increased in the ACF group accompanied by a restriction in systolic (LVEF: 72±2 vs. 39±3%) and diastolic (dP/dtmin.: −10,435±942 vs. −5982±745mmHg/s) function (p<0.01). Activated caspase-3 was significantly increased in failing hearts concomitant with mitochondrial leakage of cytochrome c into the cytosol. Finally, electron microscopy of the left ventricle (LV) of ACF rats revealed pronounced ultrastructural changes in >70% of examined cardiomyocytes, such as nuclear chromatin condensation, myofibril loss and disarray, contour irregularities and amorphous dense bodies, mitochondriosis and damaged cell–cell-contacts between cardiomyocytes. ConclusionsVolume overload induced heart failure is associated with activation of the mitochondrial apoptotic pathway. In addition, electron microscopy of the LV revealed direct ultrastructural evidence of extended myocardial apoptosis in ACF rats.

An endocrine hypothesis for the genesis of atrial fibrillation: the hypothalamic-pituitary-adrenal axis response to stress and glycogen accumulation in atrial tissues.

Background:The underlying role of intracellular glycogen in atrial fibrillation is unknown. Experimental models developed in the goat have shown an increase of intracellular glycogen concentration in atrial myocytes resulting from prolonged pacing induced atrial fibrillation (AF). These observed glycogen molecules are as a result of structural remodeling and are known to replace the intracellular myofibrils causing myolysis in studies done in different animal models. The accumulation of glycogen is progressively and directly related to the duration of pacing-induced AF. Similar responses have been seen in clinically derived atrial tissues.Aims:We intend to present an endocrine hypothesis supported by published evidence that stress acting through the hypothalamic-pituitary-adrenal axis (HPA) is a contributing metabolic factor responsible for the increase of glucose levels via the hormone cortisol. This excess glucose is then metabolized by the myocytes during each heart beat and stored as glycogen. A literature search was done, and published evidence supporting stress was shown to be the main factor for the formation of glucose leading to glycogen deposition to in the cardiac myocytes.Results:Stress on the HPA axis stimulates the adrenal glands to release the hormone cortisol in the blood stream; this in turn increases the cardiac tissue glycogen concentration. It is also known that during each beat, excess glucose is removed by the myocytes and stored as glycogen. As aforementioned, in the cardiac myocytes, dense glycogen content with/without loss of myofibrils has been detected in both human and animal models of AF.Conclusions:We hypothesize that the increase of the intrinsic glycogen concentration and distribution is a result of a metabolic disruption caused by stress through the HPA Axis. For example, in atrial myocytes, the glycogen molecules impede the normal intercellular communications leading to areas of slow conduction favoring reentrant-based AF.

Effects of Molsidomine against Doxorubicin-Induced Cardiotoxicity in Rats

Purpose: To explore the protective and curative effects of molsidomine (MOL) on doxorubicin (DOX)-induced cardiac damage in the in vivo rat heart. Methods: Forty rats were randomized into five groups (n = 8): (1) the control group; (2) the MOL group (10 mg/kg for 21 days); (3) the DOX group (a single dose of 20 mg/kg); (4) the DOX + MOL group (3 days after the single dose of DOX, 10 mg/kg MOL continued for 21 days), and (5) the MOL + DOX group (24 h after a 21-day regimen of 10 mg/kg MOL, a single dose of DOX). The rats were monitored for mean arterial blood pressure, heart rate, O₂ saturation, and electrocardiography. Heart tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and nitric oxide (NO) were determined. Results: Blood pressure and O₂ saturation values indicated a significant decrease in the DOX group compared with the control group. T negativity was observed in 4 of 8 rats in the DOX group, in 1 of 8 rats in the DOX + MOL group, and in 4 of 8 rats in the MOL + DOX group. MDA levels were significantly higher in the DOX group. SOD, GSH, and NO levels were significantly lower in the DOX group compared with the other groups. There was no statistically significant difference in the CAT levels in any of the study groups compared with controls. DOX treatment induced morphological alterations, such as disorganization of cardiomyocytes, loss of myofibrils, and cytoplasmic vacuolization in the heart. On the other hand, histological damage was significantly reduced in the DOX + MOL and MOL + DOX groups. Conclusion: This study implies that there are cardioprotective effects of MOL on DOX-induced cardiotoxicity.

The Influence of Age on Serum Concentrations of Cardiac Troponin I

Cardiac troponins serve as serum biomarkers of myocardial injury. The current study examined the influence of age on serum concentrations of cardiac troponin I (cTnI). An ultrasensitive immunoassay was used to monitor cTnI concentrations in Sprague-Dawley (SD) rats and Erythrocebus patas monkeys of different ages. The mean cTnI concentrations were highest in 10-day-old rats compared to 25-, 40-, and 80-day-old SD rats. Cardiomyocyte remodeling was apparent in hearts from 10-day-old SD rats as evident by hypercellularity, irregularly shaped nuclei, and moderate numbers of myocytes undergoing mitosis and apoptosis. The mean concentration of cTnI in 5 newborn monkeys was considerably higher than that of three 1-year-old monkeys. Evidence of cardiomyocyte remodeling was also observed in these newborn hearts (loss of myofibrils and cytoplasmic vacuolation). Commercial animal serum samples were also analyzed. The concentrations of cTnI detected in fetal equine and porcine serum were considerably higher than that found in adult equine and porcine serum samples Likewise, fetal bovine serum had higher cTnI concentrations (>2,400 pg/ml) than did adult caprine and laprine samples (2.5-2.7 pg/ml). The present study found age-related differences in cTnI concentrations, with higher levels occurring at younger ages. This effect was consistent across several animal species.

Relationship between metabolic and structural remodeling during DCM progression in human

Introduction: Whether switch of energy substrates in dilated cardiomyopathy (DCM) is adaptive or causally related to myocardial pathology is still controversial. Thus the aim of our study was a link between structural and metabolic remodeling during DCM progression to heart failure (HF). Population study and methods. Archival RV tissue samples forty-four patients analysed histopathologically and ultrastructurally were subdivided into three groups according to EF determined at the time of admission: group (I) EF 45-55% (n=14, age 23,23±11,75 years), (II) EF 30-44% (n=15, age 24,67±10,36 years), (III) EF <30% (n=15, age 48,66±13,8 years). RNA from ten frozen samples belonging to mentioned groups was isolated and expression levels of PPARα, FAT/CD36, GLUT-4, and CPT-1 investigated. Results: Analysis revealed that with decrease of EF from 45-55% to about 35% was related to increased tissue fibrosis (from 6,15±5,45% to 8,29±5,26%) and cardiomyocytes hypertrophy (from diameter of 17,55±8,07 μm to 18,24±4,62 μm) with accompanying slight reduction of contractile apparatus and increase of mitochondria number and glycogen abundance, and transition of desmin expression from normal pattern to aggregates are characteristic features. Parallel, increase of PPARα and CPT-1, and GLUT-4 and decrease of FAT/CD36 gene expression was observed. While, in myocardial tissues of hearts with decreased EF to <30% was observed significant increase of fibrosis (14,23±12,4%), and not much progress in cardiomyocytes hypertrophy (cells diameter 18,75±4, 44 μm) but significant cell remodeling (related to significant loss of myofibrils, and glycogen, and mitochondria, and desmin cytoskeleton expression, and lipid droplets occurrence). These was accompanying by increased expression of genes - PPARα and FAT/CD36 and CPT-1 comparing to group II about 50% and 150% and 20% respectively, and lowered expression of GLUT4 gene. Conclusions: Obtained data reveled that switch of energy substrates precede cardiomyocytes structural disturbances in DCM. Furthermore, in early disease state glucose metabolism is activated probably to compensate decreased fatty acid transport, particularly that reserve of intracellular glucose is available. While, increase of PPARα and FAT/CD36 genes in later disease stage together with decrease of mitochondria number may lead to toxic lipids storage and cell injury. These data suggest the energetic metabolism as therapeutic purpose to prevent cardiac remodelling in DCM.

Visceral Smooth Muscle α-Actin Deficiency Associated With Chronic Intestinal Pseudo-obstruction in a Bengal Cat (Felis catus × Prionailurus bengalensis)

An adult Bengal cat (Felis catus × Prionailurus bengalensis) with a prolonged history of partial anorexia, regurgitation, and weight loss and a clinical, radiographic, and ultrasonographic diagnosis of persistent megaesophagus and gastrointestinal ileus was submitted for necropsy. The intestinal tract was diffusely distended by gas and fluid with appreciable loss of muscle tone and an absence of luminal obstruction, consistent with the clinical history of chronic intestinal pseudo-obstruction. Histologically, the autonomic nervous system was intact, but the smooth muscle within the gastrointestinal wall exhibited a marked basophilia that was most pronounced in the jejunum. Immunohistochemistry for neurofilament, synaptophysin, CD117, and desmin demonstrated that the number of myenteric ganglia, number of interstitial cells, and leiomyocyte desmin content were similar when compared with the unaffected age- and species-matched control. Immunohistochemistry for smooth muscle α-actin demonstrated a striking loss of immunoreactivity, predominantly in the circular layer of the jejunum, that corresponded with the tinctorial change in leiomyocytes. Transmission electron microscopy revealed loss of myofibrils, loss of organelle polarity, and significantly larger central mitochondria (megamitochondria) in affected leiomyocytes, as well as nonspecific degenerative changes. Although the presence of a primary leiomyopathy and a causal relationship could not be confirmed in this case, leiomyopathies are considered a cause of chronic intestinal pseudo-obstruction in human medicine, and loss of smooth muscle α-actin immunoreactivity is one recognized marker for intestinal dysmotility.

N-Acetylcysteine prevents doxorubucine-induced cardiotoxicity in rats

This study is designed to observe the effects of N-acetylcysteine (NAC) on doxorubucine-induced cardiac toxicity in rats both histologically and biochemically. Totally 32 rats divided equally into four groups were studied. The first group received only 200 mg/kg NAC intraperitoneal (i.p.) once every 24 h for 5 days (group 1); the second group received 20 mg/kg doxorubucine (DOX) i.p. single dose plus NAC 200 mg/kg i.p. once every 24 h for 5 days (group 2); the third group received DOX 20 mg/kg DOX i.p. single dose (group 3) and the fourth group, which is also the control group, received saline (group 4). Following 24 h of the final dose, blood samples were drawn from a portal vein and heart tissue were obtained. Tissue thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) levels were highest in the DOX group. In the DOX-treated rats, serum TBARS, NO, aspartate transaminase, lactate dehydrogenase and creatine kinase levels were highest when compared with other groups. Except for serum superoxide dismutase levels, all other parameters differed significantly between the DOX plus NAC group and the DOX group. In the DOX plus NAC group, general architecture was preserved better than the DOX group and myofibril loss was minimal compared with the DOX group. NAC demonstrated, both biochemically and histologically, to be effective in the prevention of DOX-induced cardiotoxicity in rat models. Evaluation of NAC's effect on DOX toxicity warrants further clinical trials on cancer patients.

Dedifferentiated Cardiac Myocytes in Patients with End-Stage Heart Failure

Purpose: Transplantation is a main therapy for patients with end-stage heart failure (HF), characterized by irreversible loss of cardiac myocytes (CM) and contractile material leading to myocardial pump failure. New experimental data on zebra fish and newts demonstrate that postnatal CM retain some regenerative capacity. According to recent reports, myocardium after injury might recover via division of preexisting mature CM, differentiation of stem cells or through the amplification of dedifferentiated cells. Nevertheless, the process of heart regeneration is still mostly unknown and the knowledge is mainly restricted to animal models and data in vitro. The possibility of a human myocardial regenerative capacity could give an opportunity for the development of new therapeutic approaches and could provide new diagnostic perspectives. Human heart explants can be useful for the elucidation of peculiarities and mechanisms of endogenous heart plasticity. Methods and Materials: We studied explanted hearts of 12 patients with HF (NYHA class III & IV) and 2 controls (normal myocardium). Results: In myocardium of patients with HF we found a great number of dedifferentiated CM that re-expressed fetal heart markers such as α-smooth muscle actin (SMA), α-smooth muscle actinin (SMAct) and atrial natriuretic peptide (ANP). The number of dedifferentiated CM varied in different patients, but we didn't find any of these markers in our controls. CM expressing different fetal heart markers were often localized very close to each other forming “regenerating” loci and sometimes even co-localized. To estimate the extent to which CM dedifferentiate, we analyzed the samples using electron microscopy. Dedifferentiating CM were characterized by disarrangements and loss of myofibrils, vacuolization of cytoplasm, mitochondrial lesions, accumulation of glycogen granules, convolutions of cariotheca, but nevertheless without features of degeneration or apoptosis. It is notable, that an increase of dedifferentiated CM in patients with HF was also accompanied by an activation of fetal genes in the extracellular matrix (ECM) namely by the expression of the matricellular protein tenascin. Conclusions: Summarizing our data it can be concluded: 1) in human hearts an endogenous regenerative potential can be realized through the dedifferentiation of CM; 2) dedifferentiated CM displayed some staging indicated by expression of different embryonic heart markers; 3) the dedifferentiation of CM is accompanied or probably initiated by a modification of the myocardial microenvironment.

Effect of bisphenol A on the myocardium of adult male albino rats and the possible role of lycopene

Introduction Despite the wide use of bisphenol A (BPA) in plastic and epoxy resin industries, its side effects have been a subject of controversy. Lycopene (a natural carotenoid) has a protective role in many cardiovascular diseases. This work aimed to study the biochemical and structural changes induced by BPA in the myocardium of adult rats and evaluate whether coadministration of lycopene could alter these effects. Materials and methods Twenty adult male albino rats were divided into four equal groups. Group I was the control. Group II received lycopene (4mg/kg body weight/day orally) for 8 weeks. Group III was given BPA (50mg/kg body weight/day orally) for 8 weeks. Group IV was given both BPA and lycopene in the same previous dose and for the same duration. At the end of the experiment, rats were anesthetized, and their hearts were taken and prepared for histological and biochemical studies. Area percentages of the collagen content and positive immune reaction for vimentin were morphometrically and statistically analyzed. Results Examination of group III revealed that some myocytes had a deeply acidophilic cytoplasm and were devoid of nuclei. Some myocytes appeared with pale vacuolated cytoplasm, and some had focal loss of myofibrils. Their sarcoplasm contained many distorted mitochondria and dilated T-tubules. Their nuclei were variable in shape. They were peripherally located, or deeply indented, or heterochromatic. Many interstitial cells, inflammatory cells, congested blood capillaries, and areas of edema were seen. A significant increase in collagen fibers and in the area percentage of positive immune reaction for vimentin compared with the control group was observed. Examination of group IV showed that the cardiac muscle cells had a normal architecture except for a few distorted muscle fibers and many congested blood capillaries. There was a significant decrease in the area percentage of positive immune reaction for vimentin in group IV compared with group III. The current study revealed significant increase in serum malondialdehyde, whereas tissue reduced glutathione and catalase showed significant decrease in group III compared with the control group. In contrast, in group IV, malondialdehyde showed significant decrease, and tissue reduced glutathione and catalase showed significant increase, compared with group III. Conclusion Long-term exposure to BPA could induce structural and biochemical changes in rat cardiac muscle. This could be partially minimized by concomitant administration of lycopene.