Cardiotoxicity associated with many cancer drugs is a critical issue facing physicians these days and a huge hurdle that must be overcome for a side effects-free cancer therapy. Survival of cardiac myocytes is compromised upon the exposure to certain chemotherapeutic drugs. Unfortunately, the mechanisms implicated in cardiac toxicity and the pathways governing myocyte survival are poorly understood. The following thesis addresses the mechanisms underlying the cardiotoxicity of two anticancer drugs, doxorubicin (DOX) and Imatinib mesylate (Gleevec). Transcription factor GATA-4, has recently emerged as an indispensable factor in the adult heart adaptive response and cardiomyocyte survival. Therefore, the specific aim of this project was to determine the role of GATA-4, its upstream regulators, as well as partners in survival. A combination of cell and molecular techniques done on in vivo, and ex vivo models were utilized to tackle these issues. In this study, we confirmed the cardiotoxicity of the anticancer drug, Imatinib mesylate and found to be age dependent. GATA-4, already known to be implicated in DOX-induced toxicity, was confirmed as an Imatinib target. At the molecular level, we identified IGF-1 and AKT as upstream regulators of GATA-4. Moreover, we confirmed ZFP260 (PEX-1), a key regulator of the cardiac hypertrophic response, as a GATA-4 collaborator in common prosurvival pathways. Collectively, these results provide new insights on the mechanisms underlying drug-induced cardiotoxicity and raise the exciting possibility that cancer drugs are negatively affecting the same prosurvival pathway(s), in which GATA-4 is a critical component. Therapeutic interventions aimed at enhancing GATA-4 activity may be interesting to consider in the context of treatments with anticancer drugs.

Dilated Cardiomyopathy (DCM) with conduction disease and Atrial Fibrillation (AF) are the two cardiac-specific diseases associated with lamin A/C gene (LMNA) mutations. Protein Kinase C Alpha, (PKCα) functions as a nodal integrator of cardiac contractility by “sensing” intracellular calcium and signal transduction. PKCα has been implicated in heart failure and cardiac hypertrophy. Moreover, abnormal PKCα function results in irregular atrial potassium channel activity associated with chronic AF PKCα is a lamin A/C binding partner. Thus, the deregulation of PKCα signaling can contribute to the development of DCM and AF. Our hypothesis is that the AF (Thr528Met), DCM-associated (Arg541Cys) and (Arg541Gly) and DCM/AF-associated (Tyr481Stop) LMNA variants will disrupt the cellular distribution of PKCα therefore resulting in impaired PKCα function. The first objective was to phenotypically characterise Arg541Cys LMNA variant in murine skeletal myoblasts cell line (C2C12) in comparison to cellular phenotypes induced by LMNA variants associated with AF, DCM and DCM with AF. Arg541Cys lamin A and C variants formed circular and sickle-shaped lamin A/C in the nucleus of C2C12 cells. The second objective was to determine the effect of these lamin variants on cellular distribution of PKCα in C2C12 cells. PKCα mislocalized into the nucleus of C2C12 cells transfected with AF and DCM-associated variants (Thr528Met and Arg541Cys). Colocalization analysis showed significant increase in PKCα in the nucleus of AF (Thr528Met) and DCM (Arg541Cys) variants when lamin A and C, were co-transfected compared to wild-type, DCM (Arg541Gly) and DCM/AF (Tyr481Stop) variants. Densitometry analysis showed statistically significant increase in phosphorylated PKCα, the active form of PKCα, in nuclear and cytoplasmic extracts of C2C12 cells expressing Arg541Cys variant. Densitometry analysis also showed statistically significant increase in non-phosphorylated PKCα in the nuclear extract of Thr528Met variant expressing cells. The third objective was to determine the effect of AF and DCM-associated variants on the activity of PKCα. PKCα activity is quantified by measuring the phosphorylation of a known phosphorylated PKCα substrate. Alpha-6-tubulin phospho (Ser165) is phosphorylated by PKCα. Hence, this was used to quantify PKCα activity. No statistical significance was observed in the level of phosphorylated alpha-6-tubulin at (Ser165) in the C2C12 cells that were transfected with lamin A and C variants compared to wild type. Furthermore, PKCα phosphorylation state is cyclic in nature and this could have had an impact on the phosphorylation state of the chosen substrate in this study. The functional consequence of nuclear translocation of PKCα with respect to laminopathies is unknown. Abnormal activation of the Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK1/2) which are branches of the mitogen-activated protein kinase (MAPK) signalling cascade in hearts of mice, and humans prior to the onset of cardiomyopathy. These findings have been associated to cardiac disease-causing lamin A/C alteration to signal transduction pathways implicated in heart function and cardiomyopathy. Human LMNA cardiomyopathy, could lead to abnormal activation of MAPK signalling pathways via abnormal PKCα activation in cardiomyocytes.

Background-In cardiomyocytes from patients with hypertrophic cardiomyopathy, mechanical dysfunction and arrhythmogenicity are caused by mutation-driven changes in myofilament function combined with excitation-contraction (E-C) coupling abnormalities related to adverse remodeling. Whether myofilament or E-C coupling alterations are more relevant in disease development is unknown. Here, we aim to investigate whether the relative roles of myofilament dysfunction and E-C coupling remodeling in determining the hypertrophic cardiomyopathy phenotype are mutation specific. Methods and Results-Two hypertrophic cardiomyopathy mouse models carrying the R92Q and the E163R TNNT2 mutations were investigated. Echocardiography showed left ventricular hypertrophy, enhanced contractility, and diastolic dysfunction in both models; however, these phenotypes were more pronounced in the R92Q mice. Both E163R and R92Q trabeculae showed prolonged twitch relaxation and increased occurrence of premature beats. In E163R ventricular myofibrils or skinned trabeculae, relaxation following Ca2+ removal was prolonged; resting tension and resting ATPase were higher; and isometric ATPase at maximal Ca2+ activation, the energy cost of tension generation, and myofilament Ca2+ sensitivity were increased compared with that in wildtype mice. No sarcomeric changes were observed in R92Q versus wild-type mice, except for a large increase in myofilament Ca2+ sensitivity. In R92Q myocardium, we found a blunted response to inotropic interventions, slower decay of Ca2+ transients, reduced SERCA function, and increased Ca2+/calmodulin kinase II activity. Contrarily, secondary alterations of E-C coupling and signaling were minimal in E163R myocardium. Conclusions-In E163R models, mutation-driven myofilament abnormalities directly cause myocardial dysfunction. In R92Q, diastolic dysfunction and arrhythmogenicity are mediated by profound cardiomyocytesignaling and E-C coupling changes. Similar hypertrophic cardiomyopathy phenotypes can be generated through different pathways, implying different strategies for a precision medicine approach to treatment.

Thyroid storm (TS) is a rare life threatening endocrine emergency. Estimates for mortality rate for untreated TS ranges from 50%-90%[1,2].; however if managed appropriately, mortality drops to less than 20%[2]. Management can include glucocorticoids, propranolol, propylthiouracil(PTU) or methimazole and iodine solution. Each have established roles in controlling the hyperdynamic state in the storm. What is not well established is subclinical cardiomyopathy that may exist with chronic uncontrolled hyperthyroidism. We present a case in which propranolol, used appropriately, led to cardiovascular collapse during the management of a thyroid storm. 48 year old female with a medical history significant for hypertension presented with a 1 day history of severe dyspnea. On arrival vitals were: BP 177/103, pulse 127, RR 28 and pulse ox 92% on room air. She had anasarca and a GCS of 6. She was intubated for airway protection. Head CT was normal. Labs were sodium 128, bicarbonate 18, glucose 38, anion gap 14, lactic acid 5, leukocytes of 12000, Hb 7.3. ABG was pH 7.04, PCO2 45, PaO2 138 on 100% O2 at PEEP of 10, immediately after intubation. TSH was undetectable, FT4 was > 8ng/dL with FT3 of 11pg/mL. Echocardiogram showed EF of 45%, RV dilation and biatrial enlargement. She received glucocorticoids, PTU and oral propranolol. Shortly afterwards she became bradycardic, hypotensive then developed pulseless electrical activity (PEA) despite glucagon and aggressive IV fluids. ROSC was achieved after 8 minutes of ACLS protocol. Within minutes she became bradycardic and hypotensive again then became pulseless again despite glucagon and attempts at transcutaneous pacing. After ROSC with ACLS protocol, she was eventually stabilized with aggressive IV fluid, 5 vasopressors and a bicarbonate drip. That night, she had a third cardiac arrest. After ROSC, an emergency bedside laparotomy was performed for decompression of compartment syndrome. Her hospital course was complicated by hematologic abnormalities requiring multiple blood products, gastrointestinal blood loss, NSTEMI and dialysis dependent renal failure. The concept of thyrocardiac disease must be kept in mind when managing a thyroid storm. In long standing hyperthyroidism, the resulting cardiomyopathy is compensated by tachycardia and increased sensitivity to catecholamines [3]. This compensatory mechanism depends on tachycardia to maintains adequate cardiac output. Failure to consider this led to our therapeutic misadventure. Current management of TS includes the use of propranolol to lessen the adrenergic effect on the heart and to inhibit peripheral conversion of T4 to T3. This patient’s experience suggested that abrupt disruption of this compensatory state with beta blockade puts the body at risk for cardiovascular collapse. Until management guidelines are updated, it is imperative to for clinicians to avoid beta blockers or use short acting beta blockers with extreme caution when managing TS.

Germ cell tumors (GCT) are uncommon malignancies in adult males and comprise less than 1% of male cancers. Due to highly curative nature and productive life years gained after treatment; reduction of chemotherapy related toxicities becomes vital. Cisplatin is the backbone of GCT chemotherapy, & is related to myocardial injury, thromboembolism & vasculitis. Though it should not be replaced with Carboplatin, however in certain circumstances, its use maybe unsafe; especially in cases when patient have prior myocardial infarction. We report a case of Takotsubo cardiomyopathy (TCM)secondary to GCT diagnosis in a young male. This patient presented withsymptoms of myocardial infarction however, coronary angiography was normal and a diagnosis of TCM was made. Though, it is rare but a unique challenge, as whether Cisplatin use would be safe in this particular scenario? On one hand patient had stress related myocardial injurywhile he was also at risk of further Cisplatin induced complications.There are no clear cut guidelines, so after informed consent his treatment regimen was modified to EC (Etoposide/Carboplatin) instead of EP (Etoposide/Cisplatin). Patient has completed 4.6 years of follow-up without any evidence of relapse. We suggest informed decisions and to weigh the pros and cons of using an inferior regimen, in order to achieve same long term prognosis while preventing any acute complications,in younger patients with curable cancers.

No description available.

A predominantly right ventricular variant of isolated noncompaction cardiomyopathy is a potentially lethal disease entity, which only recently has become recognized in the clinical and cardiac imaging literature. There are currently few established morphologic criteria for the diagnosis other than right ventricular dilation and presence of excessive regional trabeculation. To date, there have been no autopsy reports of cases following either clinical diagnosis or sudden death. We report 2 adult cases of sudden unexpected death in which unexplained right ventricular dilation and prominent apical hypertrabeculation were the principal findings. The gross and microscopic results suggest pathological similarities between, or coexistence of, right ventricular noncompaction and arrhythmogenic right ventricular cardiomyopathies.

Objective: Unusual clinical course Background: "Bath salts" is the street name for a group of recently identified and increasingly abused stimulant synthetic cathinones that are associated with multiple systemic effects. We present a case of a patient who developed reversible dilated cardiomyopathy secondary to their use. Case Report: A 27 year old male with no past medical history was brought to emergency department with agitation. He had been inhaling and intravenously injecting "bath salts", containing a mephedrone/Methylenedioxypyrovalerone (MDPV) combination. On presentation, he was tachycardic, hypotensive and febrile. His initial labs showed an elevated white count, creatinine and creatinine phosphokinase levels. His erythrocyte sedimentation rate; C-reactive protein; urinalysis; urine drug screen; Human Immunodeficiency Virus, hepatitis, coxsackie, and influenza serology were normal. EKG showed sinus tachycardia. An echocardiogram was done which showed dilated cardiomyopathy with an ejection fraction (EF) of 15-20% and global hypokinesia. A left heart catheterization was done and was negative for coronary artery disease. At a 20 week follow up, he had stopped abusing bath salts and was asymptomatic. A repeat echocardiogram showed an EF of 52%. Cocnlusions: Bath salts (MDPV, mephedrone) are synthetic cathinones with amphetamine/cocaine like properties with potential cardiotoxic effects. Cardiovascular manifestations reported include tachycardia, hypertension, myocardial infarction, arrhythmias and cardiac arrest. "Bath salts" can also cause severe reversible dilated cardiomyopathy. Prior to diagnosis, other causes of cardiomyopathy including ischemic, infectious, familial, immunological, metabolic and cytotoxic may need to be ruled out; as was done in our patient.

With the advent of more effective therapies for human immunodeficiency virus (HIV) infection, HIV-infected patients are living longer and cardiovascular disease is becoming more obvious in this population. Patients with HIV infection represent one of the most rapidly developing groups with cardiovascular disease globally. Cardiovascular disease complicating HIV infection is likely to contribute to burgeoning healthcare costs. Pericarditis, myocarditis, cardiomyopathy, atherosclerotic coronary vasculopathy, arterial aneurysms, pulmonary hypertension, and endocarditis occur with increased frequency in these patients. Pedcardial tamponade, dilated cardiomyopathy, endocarditis, and vasculopathy can lead to fatal outcomes in this population. The advent of cardiomyopathy heralds a very poor prognosis in patients infected with HIV. Coronary vasculopathy without obvious risk factors can lead to myocardial ischemia in young patients infected with the virus. MoreoVer, the protease inhibitors used to treat HIV infection induce a syndrome of lipodystrophy and dyslipidemia that may be associated with accelerated atherosclerosis as well as insulin resistance. All these factors contribute to increased cardiovascular morbidity and mortality in the HIV-infected population. HIV infection, opportunistic infections, secreted viral proteins such as gp120 (envelope protein) or Tat (transactivator of viral transcription), and cytokines elaborated during the course of HIV infection of the immune system all contribute to pathogenesis of these disorders. Further basic and clinical studies are required to understand the pathogenesis of cardiovascular complications and develop appropriate management strategies for these patients.

A predominantly right ventricular variant of isolated noncompaction cardiomyopathy is a potentially lethal disease entity, which only recently has become recognized in the clinical and cardiac imaging literature. There are currently few established morphologic criteria for the diagnosis other than right ventricular dilation and presence of excessive regional trabeculation. To date, there have been no autopsy reports of cases following either clinical diagnosis or sudden death. We report 2 adult cases of sudden unexpected death in which unexplained right ventricular dilation and prominent apical hypertrabeculation were the principal findings. The gross and microscopic results suggest pathological similarities between, or coexistence of, right ventricular noncompaction and arrhythmogenic right ventricular cardiomyopathies.