Doxorubicin-induced cardiac toxicity

The protective role of curcumin in cardiovascular diseases

Curcumin (diferuloylmethane) is a polyphenol responsible for the yellow color of the curry spice turmeric. It has been used in a variety of diseases in traditional medicine. Modern scientific research has demonstrated its anti-inflammatory, anti-oxidant, anti-carcinogenic, anti-thrombotic, and cardiovascular protective effects. In this review, we focused mainly on the effects of curcumin on the cardiovascular system. The antioxidant effects of curcumin have been shown to attenuate adriamycin-induced cardiotoxicity and may prevent diabetic cardiovascular complications. The anti-thrombotic, anti-proliferative, and anti-inflammatory effects of curcumin and the effect of curcumin in decreasing the serum cholesterol level may protect against the pathological changes occurring with atherosclerosis. The p300-HAT inhibitory effects of curcumin have been demonstrated to ameliorate the development of cardiac hypertrophy and heart failure in animal models. The inflammatory effects of curcumin may have the possibility of preventing atrial arrhythmias and the possible effect of curcumin for correcting the Ca(2+) homeostasis may play a role in the prevention of some ventricular arrhythmias. The preclinical studies from animal to clinical data in human are discussed.

Cytoprotective effect of anthocyanins against doxorubicin-induced toxicity in H9c2 cardiomyocytes in relation to their antioxidant activities

The effect of six anthocyanidins and seven anthocyanins against doxorubicin (Dox)-induced cardiotoxicity in relation to their antioxidant properties was investigated in H9c2 cardiomyocytes. The exposure to Dox, a highly effective cytotoxic agent against cancer cells, induced significant cell death, intracellular reactive oxygen species (ROS), and lipid peroxidation in non-tumorigenic cardiac cell culture. All anthocyanidins (50 and/or 100 microM) significantly increased cell survival up to 40% compared to the Dox-treated controls. Especially, cyanidin and delphinidin, which have an ortho-dihydroxyl moiety (3',4'-OH) on the flavylium skeleton, demonstrated the most potent protection against cytotoxicity (EC(50) of 113 and 179 microM, respectively) as well as lipid peroxidation induced by Dox treatment. In contrast, seven anthocyanins having a glycosidic moiety showed little effect in cytoprotection and lipid peroxidation, although they markedly blocked intracellular ROS generation. All anthocyanidins and anthocyanins had higher TEAC values than ascorbic acid, and efficaciously scavenged superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)), peroxynitrite (ONOO(-)) and nitric oxide (NO), but not hydroxyl radical (OH()). Their O(2)(-) scavenging activity was well correlated with the observed cytoprotection (r=0.67, p<0.05). These results suggest that anthocyanidins can ameliorate Dox-induced cardiotoxicity by, at least in part, scavenging of O(2)(-) generated by Dox.

Radiation protects adriamycin-induced apoptosis

Combined radiotherapy and chemotherapy have represented major advance in the therapeutic management of cancer therapy. Anthracycline antineoplastic agents are limited by a high incidence of severe and usually irreversible cardiac toxicity, the cause of which remains controversial. When the primary cardiomyocytes isolated from neonatal rats were preirradiated by gamma-ray, the cells were highly resistant to adriamycin-induced apoptosis. This study shows that irradiation inhibited apoptosis by enhancing Bcl-2, attenuating Bax induction, and preventing collapse of mitochondrial membrane potential (delta psi), cytochrome c release into cytoplasm and caspase-3, -6 and -9 activations. In addition, the preirradiation stimulated the activity of manganese-superoxide dismutase (Mn-SOD) and the expression of Mn-SOD mRNA and protein. Adriamycin decreased Mn-SOD activity but did not change the activity of copper/zinc (Cu/Zn)-SOD under either pre- or nonirradiated condition. Phosphothioate-linked antisense against Mn-SOD, which specifically knocked down the activity of Mn-SOD but not that of Cu/Zn-SOD, reversed irradiation-induced protective effect in adriamycin-exposed cardiomyocytes. These data suggest that the irradiation-induced expression of Mn-SOD plays an important role in irradiation-mediated protection in adriamycin-exposed rat ventricular cardiomyocytes.

Evaluation of cardiac reserved function by high-dose dobutamine-stress echocardiography in asymptomatic anthracycline-treated survivors of childhood cancer

BACKGROUND

The aim of this study was to evaluate cardiac function and cardiac reserved function in asymptomatic anthracycline-treated long-time survivors of childhood cancer using dobutamine (DOB) stress echocardiography.

METHODS

A total of 26 patients (19 males and 7 females) were divided into four groups according to cumulative dose of anthracycline (ATC): non-anthracycline group (N group), seven cases; low anthracycline cumulative dose group (L group), five cases (<or=200 mg/m(2)); medium anthracycline cumulative dose group (M group), seven cases (200-<400 mg/m(2)); high anthracycline group (H group), seven cases (>or=400 mg/m(2)). DOB infusion was begun at 5 microg/kg per min (gamma) and increased up to 30 gamma. Cardiac function and cardiac reserved function at rest, after low-dose and high-dose DOB stress, were estimated.

RESULTS

In the H group, % left ventricular posterior wall thickening (%PWT) at rest and ratio of maximum early filling peak velocity (E) and atrial contraction peak velocity (A) from the left ventricular transmitral flow wave (E/A) and %PWT at DOB 5 gamma stress were significantly lower than in other groups (P<0.05). After DOB 30 gamma stress in groups given>00 mg/m(2) end-systolic wall stress was significantly higher and E/A and %PWT were significantly lower than those of other groups (P<0.05). ATC cumulative dose strongly correlated with %PWT after DOB 30 gamma stress (P<0.001).

CONCLUSIONS

Subclinical ATC cardiotoxicity was detected by high-dose DOB stress echocardiography at lower cumulative doses than with other methods. %PWT appears to be a useful index for detection of ATC cardiotoxicity.

Protective effect of CardiPro against doxorubicin-induced cardiotoxicity in mice

The effect of CardiPro, a polyherbal formulation, with an antioxidant property, has been studied on doxorubicin (DXR)-induced cardiotoxicity in mice. CardiPro (150 mg/kg b.w., twice daily was administered orally for 7 weeks along with four equal injections (each containing 4.0 mg/kg b.w., DXR) intraperitoneally, once weekly (cumulative dose 16 mg/kg). After a 3-week post DXR treatment period, cardiotoxicity was assessed by noting mortality, volume of ascites, liver congestion, changes in heart weight, myocardial lipid peroxidation, antioxidant enzymes and histology of heart. DXR-treated animals showed higher mortality (50%) and more ascites. Myocardial SOD and glutathione peroxidase activity were decreased and lipid peroxidation was increased. Histology of heart of DXR-treated animals showed loss of myofibrils and focal cytoplasmic vacuolization. CardiPro significantly protected the mice from DXR-induced cardiotoxic effects as evidenced by lower mortality (25%), less ascites, myocardial lipid peroxidation, normalization of antioxidant enzymes and minimal damage to the heart histologically. Our data confirm the earlier reports that DXR cardiotoxicity is associated with the free radical-induced tissue damage. Administration of CardiPro, with an antioxidant property, protected the DXR-induced cardiotoxicity in mice.

Saeng-Ji-Hwang has a protective effect on adriamycin-induced cytotoxicity in cardiac muscle cells

This study examined the effect of Saeng-Ji-Hwang (SJH: Radix Rehmanniae) on cardiac muscle cells. Adriamycin-exposed H9C2 cardiac muscle cells were treated with a water extract of SJH. The adriamycin induced cell death and caspase-3 activation were significantly inhibited by SJH (2 mg/ml), which can be explained by the increase in Bcl-2 expression and the inhibition of Bax expression. Adriamycin reduced the Mn-SOD protein expression level in H9C2 cardiac muscle cells but a SJH treatment partially but significantly reversed this effect. Manganese (Mn)-TBAP or Mn-TMyM--mitochondria-specific SOD mimetic agent--reduced the adriamycin-induced cytotoxicity. It was also shown that SJH inhibits the release of H2O2 and prevents lipid peroxidation in the presence of adriamycin. This study examined the intracellular GSH level, which showed that adriamycin significantly decreased the intracellular GSH level but SJH increased it. BSO, a selective inhibitor of glutamyl cysteinyl ligase, which is a rate-limiting enzyme in GSH synthesis, did not affect the viability of the cardiac muscle cells. However, a combination of BSO with SJH in the presence of adriamycin reversed the SJH-induced protection. Overall, the results suggest that SJH-associated Mn-SOD and GSH are important factors in the mechanism of the SJH-induced protective mechanism in H9C2 cardiac muscle cells.

Protective effect ofSpirulina against doxorubicin-induced cardiotoxicity

The generation of reactive oxygen species and mitochondrial dysfunction has been implicated in doxorubicin (DOX)-induced cardiotoxicity. The aim of the present study was to determine whether Spirulina, a blue-green algae, could serve as a cardioprotective agent during DOX treatment in a mouse model. Mice were treated with DOX (4 mg/kg bw, intraperitoneally), weekly, for 4 weeks. Spirulina was administered orally for 3 days twice daily, then for 7 weeks along with the four equal injections of DOX. Cardiotoxicity was assessed, at 3 weeks after the end of the DOX-treatment period, by mortality, volume of ascites, liver congestion, oxidative stress and ultrastructural changes of heart tissue. The DOX-treated animals showed higher mortality (53%) and more ascites. Myocardial damage, as assessed by ultrastructural changes, showed loss of myofibrils, cytoplasmic vacuolization and mitochondrial swelling. Myocardial superoxide dismutase and glutathione peroxidase activities were decreased and lipid peroxidation was increased. Pretreatment with Spirulina significantly protected the mice from DOX-induced cardiotoxic effects as evidenced from lower mortality (26%), less ascites, lower levels of lipid peroxidation, normalization of antioxidant enzymes and ultrastructural studies showing minimal damage to the heart. In vitro cytotoxic studies using ovarian cancer cells demonstrated that Spirulina did not compromise the anti-tumor activity of doxorubicin. These results suggest that Spirulina has a protective effect against cardiotoxicity induced by DOX and it may, therefore, improve the therapeutic index of DOX.

Notable effects of angiotensin II receptor blocker, valsartan, on acute cardiotoxic changes after standard chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone

BACKGROUND

There are three distinct types of doxorubicin-induced cardiotoxicity (acute, chronic, and late-onset). Although previous studies with animal models suggest that angiotensin II plays a key role in the process of the doxorubicin-induced cardiotoxicity, there has been no such observation in humans. This randomized study investigated whether valsartan, a new class of angiotensin II receptor blocker (ARB), can inhibit acute cardiotoxicity after doxorubicin-based chemotherapy.

METHODS

Forty consecutive patients with untreated non-Hodgkin lymphoma who were scheduled to undergo standard chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) (mean age, 56 yrs; range, 24-70 yrs) were randomized with minimization methods to receive CHOP with or without 80 mg/day of valsartan. Acute cardiotoxicity was comprehensively evaluated with neurohumoral, echocardiographic, and electrocardiographic markers before and on Days 3, 5, and 7 after the initiation of CHOP.

RESULTS

CHOP induced transient increases in the left ventricular end-diastolic diameter in an echocardiogram, the QTc interval and QTc dispersion in an electrocardiogram, and in the plasma brain and atrial natriuretic peptides. All these changes returned to nearly normal levels within a week after CHOP (P < 0.001). Notably, valsartan significantly prevented all these changes except for the elevation in atrial natriuretic peptide (P < 0.05). No significant change was observed in blood pressure or heart rate between the valsartan and control groups.

CONCLUSIONS

The results indicate that angiotensin II may play an essential role in acute CHOP-induced cardiotoxicity in humans. Future long-term studies are necessary to judge whether ARBs have a potential to prevent the chronic or late-onset types of doxorubicin-induced cardiotoxicity.

Signal transduction of the protective effect of insulin like growth factor-1 on adriamycin-induced apoptosis in cardiac muscle cells

To determine whether Insulin-like growth factor (IGF-I) treatment represents a potential means of enhancing the survival of cardiac muscle cells from adriamycin (ADR)-induced cell death, the present study examined the ability of IGF-I to prevent cell death. The study was performed utilising the embryonic, rat, cardiac muscle cell line, H9C2. Incubating cardiac muscle cells in the presence of adriamycin increased cell death, as determined by MTT assay and annexin V-positive cell number. The addition of 100 ng/mL IGF-I, in the presence of adriamycin, decreased apoptosis. The effect of IGF-I on phosphorylation of PI, a substrate of phosphatidylinositol 3-kinase (PI 3-kinase) or protein kinase B (AKT), was also examined in H9C2 cardiac muscle cells. IGF-I increased the phosphorylation of ERK 1 and 2 and PKC zeta kinase. The use of inhibitors of PI 3-kinase (LY 294002), in the cell death assay, demonstrated partial abrogation of the protective effect of IGF-I. The MEK1 inhibitor-PD098059 and the PKC inhibitor-chelerythrine exhibited no effect on IGF-1-induced cell protection. In the regulatory subunit of PI3K-p85- dominant, negative plasmid-transfected cells, the IGF-1-induced protective effect was reversed. This data demonstrates that IGF-I protects cardiac muscle cells from ADR-induced cell death. Although IGF-I activates several signaling pathways that contribute to its protective effect in other cell types, only activation of PI 3-kinase contributes to this effect in H9C2 cardiac muscle cells.

Effects of Anticancer Chemotherapeutic Drugs on the Acetylcholine Receptor-Operated Potassium Current in Guinea Pig Atrial Myocytes

The effects of 7 anticancer chemotherapeutic drugs on the muscarinic acetylcholine receptor-operated potassium current (I(K.ACh)) in guinea pig atrial myocytes were investigated using the whole cell patch clamp technique. Doxorubicin, pirarubicin, and mitoxantrone inhibited the carbachol-induced I(K.ACh) in a concentration-dependent manner in atrial cells at a holding potential of -40 mV. IC50 values of doxorubicin, pirarubicin, and mitoxantrone for the carbachol-induced I(K.ACh) were 7.7 microM, 3.7 microM, and 9.1 microM, respectively. Pirarubicin inhibited the adenosine-induced and the GTPgammaS-induced I(K.ACh) in a concentration-dependent manner (IC50=6.0 and 5.1 microM, respectively). Doxorubicin and mitoxantrone up to 100 microM did not have an influence on the adenosine-induced I(K.ACh). Doxorubicin did not affect the GTPgammaS-induced I(K.ACh). Mitoxantrone 100 microM inhibited the current only by 25%. For concentrations up to 100 microM, anticancer drugs that have chemical structures entirely different from that of doxorubicin, i.e., 5-fluorouracil, 6-mercaptopurine, cyclophosphamide, and actinomycin D, did not have an influence on the carbachol-induced I(K.ACh). Doxorubicin and chemically related compounds possess anticholinergic effects mediated via an inhibitory action on I(K.ACh) by different underlying molecular mechanisms. Doxorubicin and mitoxantrone may inhibit I(K.ACh) by the blockade of muscarinic receptors, whereas pirarubicin may inhibit the current not only via blocking the muscarinic receptors but also by depressing the functions of the K+ channel itself and/or GTP-binding proteins.

Left-right asymmetric ventricular expression of CARP in the piglet heart: regional response to experimental heart failure

BACKGROUND AND AIM

Cardiac ankyrin repeat protein (CARP), whose expression is down-regulated in response to doxorubicin (Dox) in vitro, has been proposed to be a marker of experimentally-induced cardiac hypertrophy in rodent models. In piglets, the rapid hypertrophy rate of the left ventricle (LV) as compared to that of the right ventricle (RV) represents a natural model of asymmetric ventricular enlargement. We tested whether CARP expression correlates with postnatal ventricular hypertrophy and to what extent CARP can be sensitive to Dox treatment in vivo.

METHODS

CARP mRNA and protein levels were quantified (by Northern blot hybridization, semi-quantitative RT-PCR and Western blot) in the piglet heart, both during early postnatal development and upon Dox-induced cardiomyopathy (Dox-CM).

RESULTS

The study revealed: (1) significantly augmented CARP mRNA and protein levels in the LV compared to the RV resulting in left vs. right asymmetry in ventricular CARP expression throughout early postnatal development; (2) dose- and chamber-dependent CARP mRNA and protein enrichment in ventricular myocardium in response to Dox; and (3) abolishment of asymmetric patterns of ventricular CARP expression at heart failure resulting from Dox-CM.

CONCLUSIONS

(1) CARP is differentially regulated in the LV and RV during both postnatal development and disease; and (2) monitoring of ventricular CARP expression patterns can be used for further analysis of transition from compensated to overt heart failure.

Pharmacological factors influencing anticancer drug selection in the elderly

Persons over the age of 65 years are the fastest growing segment of the US population. In the next 30 years this segment will represent more than 20% of the population. Fifty percent of all cancers occur in this age group and therefore the total cancer burden is expected to rise. Data are becoming available that will better guide the use of chemotherapy in the older patient population. Studies are presented discussing pharmacokinetic data on a number of chemotherapeutic agents with an emphasis on those that have entered clinical practice over the past few years. Many of these agents seem to have a beneficial therapeutic index, particularly in regard to older patients. Aging can affect the pharmacokinetics of chemotherapy in a number of ways. Absorption is only modified minimally by age. The greater concern with the use of oral drugs is patient compliance. Volume of distribution is affected by changes in body composition, anaemia and decreased plasma albumin concentration. There are many drugs in which renal excretion plays an important role. Decline in glomerular filtration is a consistent phenomenon with aging. Drug metabolism is primarily affected by changes in the P450 system and coadministration of drugs which also interact with this important enzyme system. The selection of chemotherapy in the elderly is frequently determined by degree of comorbidity and the patients' functional status. These factors are critical and can often determine response and toxicity. This article discusses the changes that occur with antimetabolites, camptothecins, anthracyclines, taxanes, platinum compounds, epipodophyllotoxins and vinca alkaloids. There has also been an increasing trend toward the use of oral chemotherapy. Factors that must be considered in selecting chemotherapeutic agents include limitations of saturability of absorption, patient compliance and the pharmacokinetic and pharmacodynamic changes that occur in older patients. Interpatient variability and age-related changes in drug metabolism are discussed. Careful attention to the physiological changes with age and dose adjustments necessary for end-organ dysfunction (renal, hepatic) are needed to ensure the safe administration of chemotherapy. In this article specific diseases are discussed (breast, colon, ovarian and non-small lung cancers) with recommendations for drug selection in adjuvant chemotherapy and the treatment of metastatic disease. Future studies will need to incorporate these various factors to properly evaluate chemotherapy in older patients. Research and educational initiatives targeted to this population will need to be a priority.

Sino-atrial block during anesthesia in a patient with breast cancer being treated with the anticancer drug epirubicin

IMPLICATIONS

Epirubicin, an anticancer drug, causes cardiotoxicity. We reported a case of sino-atrial block during general anesthesia in a woman with breast cancer who had received epirubicin. Anesthesiologists should be aware of the possible occurrence of sino-atrial block with epirubicin, and planting a pacemaker might be considered even in asymptomatic patients.

Pharmacology of antineoplastic agents in older cancer patients

Persons over the age of 65 years are the fastest growing segment of the United States population. In the next 30 years it will comprise over 20% of the population. Fifty percent of all cancers occur in this age group and therefore there will be an expected rise in the total cancer burden. Data is becoming available which will better guide the use of chemotherapy in the older patient population. Studies will be presented discussing pharmacokinetic data on a number of chemotherapeutic agents with an emphasis on those which have entered practice over the past few years. Many of these agents seem to have a beneficial therapeutic index, particularly in regard to older patients. There has also been an increasing trend toward the use of oral chemotherapy. Factors that must be considered in choosing chemotherapy include limitations of saturability of absorption, patient compliance and the pharmacokinetic and pharmacodynamic changes which occur in older patients. Interpatient variability and age related changes in drug metabolism are discussed. Careful attention to the physiologic changes with age, and dose adjustments necessary for end organ dysfunction (renal, hepatic) are needed to ensure the safe administration of chemotherapy.

Absence of binding of targeted analogs of somatostatin carrying cytotoxic radicals or radionuclides to growth hormone secretagogue receptors on human myocardium

Various peripheral human tissues express receptors for growth hormone secretagogue (GHS), the highest density being in the myocardium. It was also reported that some octapeptide analogs of somatostatin (SRIH) can displace radiolabeled Tyr-Ala-hexarelin from GHS receptors on the human pituitary and heart. Thus, it is possible that radionuclide analogs of SRIH such as OctreoScan and recently developed cytotoxic SRIH analogs containing doxorubicin (DOX) intended for targeted tumor therapy, could bind to these GHS receptors, compromising the safety of compounds of this type. Therefore, we determined the binding of OctreoScan and two cytotoxic SRIH analogs consisting of octapeptide carrier RC-121 and DOX (AN-162) or 2-pyrrolino-DOX (AN-238) to human myocardium specimens. None of these compounds displayed specific binding to the human heart indicating that the clinical use of SRIH analogs linked to anthracyclines or radionuclides should not be associated with increased cardiac side effects.

Treatment of large cell lymphoma in elderly patients with a mitoxantrone, cyclophosphamide, etoposide, and prednisone regimen: long-term follow-up results

BACKGROUND

Patients with aggressive non-Hodgkin lymphoma (NHL) require intensive and extensive therapy, which seems impracticable in elderly patients due to hematologic and extrahematologic toxicity. Consequent dose reduction and therapy attenuation can reduce treatment-related toxicity but also decreases therapeutic efficacy. Thus, age represents a fundamental prognostic factor that has a profound influence on both therapeutic decisions and patient outcome.

METHODS

Between January, 1990 and June, 1997, 145 patients age > 64 years (median age, 72.3 years) with a diagnosis of aggressive NHL were treated on a chemotherapy regimen that consisted of mitoxantrone, cyclophosphamide, etoposide, and prednisone.

RESULTS

Ninety-one patients (63%) achieved complete remission, and 48 patients (33%) achieved partial remission, for an overall response rate of 96%. Six patients (4%) were resistant to therapy. The overall survival rate, with a median follow-up of 66 months, was 44%, and the failure free survival rate was 42%. The disease free survival rate was 63.5%, with a median follow-up of 60 months. Multivariate survival analysis showed that the achievement of complete remission was the single most important prognostic factor, which was associated significantly with longer survival (P < 0.0001). Toxicity was moderate, with 5 deaths (3%) due to complications related to therapy.

CONCLUSIONS

The current results confirm that a protocol devised specifically for elderly patients may reduce toxicity and allow longer overall survival in this particular subset of patients.

Doxorubicin induces early lipid peroxidation associated with changes in glucose transport in cultured cardiomyocytes

Doxorubicin (DOX) has not only chronic, but also acute toxic effects in the heart, ascribed to the generation of reactive oxygen species (ROS). Focusing on the DOX-induced early biochemical changes in rat cardiomyocytes, we demonstrated that lipid peroxidation is an early event, in fact conjugated diene production increased after 1-h DOX exposure, while cell damage, evaluated as lactate dehydrogenase (LDH) release, was observed only later, when at least one third of the cell antioxidant defences were consumed. Cell pre-treatment with alpha-tocopherol (TC) inhibited both conjugated diene production and LDH release. In cardiomyocytes, DOX treatment caused a maximal increase in glucose uptake at 1 h, demonstrating that glucose transport may represent an early target for DOX. At longer times, as the cell damage become significant, the glucose uptake stimulation diminished. Immunoblotting of glucose transporter isoform GLUT1 in membranes after 1-h DOX exposure revealed an increase in GLUT1 amount similar to the increase in transport activity; both effects were inhibited by alpha TC. Early lipid peroxidation evokes an adaptive response resulting in an increased glucose uptake, presumably to restore cellular energy. The regulation of nutrient transport mechanisms in cardiomyocytes may be considered an early event in the development of the cardiotoxic effects of the anthracycline.

Left ventricular transmural systolic function by high-sensitivity velocity measurement "phased-tracking method" across the septum in doxorubicin cardiomyopathy

The clinical usefulness of doxorubicin is limited by doxorubicin-induced cardiomyopathy (DoxCM). The prognosis of this disorder is poor, and a sensitive noninvasive method for detection of DoxCM is strongly required. In this study, we examined if the transmural systolic function (TSF) obtained by the novel phased-tracking method is capable of supplying new information on DoxCM. A total of 18 healthy subjects and 30 patients with acute lymphoblastic leukemia were examined for TSF, as defined by the transmural profile of % thickening obtained by measuring the velocity at each preset point of 0.75-mm intervals. The total number of measurements was 94. In the patients, a decrease in both the peak velocity and the systolic layer thickening was observed, even in the subclinical phase of the normal ejection fraction. For healthy subjects, systolic thickening occurred in the left ventricular (LV) side of the interventricular septum (IVS), and was characterized by a sharp single-peak configuration of the profile. For the patients, however, the peak became dull and/or unclear, which indicates that a change in transmural functional distribution occurred. We concluded that the TSF is a useful measure for diagnosis of the early phase of DoxCM.

Angiotensin II type 1a receptor mediates doxorubicin-induced cardiomyopathy

Although the serious cardiotoxicity of doxorubicin (DOX), a useful chemotherapeutic agent, limits the use of this agent, the mechanism of DOX-induced cardiomyopathy remains unclear. Since accumulating evidence suggests that activation of the renin-angiotensin system is involved in the development of various types of cardiovascular remodeling, we examined the role of angiotensin II (Ang II) in DOX-induced cardiotoxicity using Ang II type 1a receptor (AT1) knockout (KO) mice. To examine the role of AT1 in the acute effects of DOX, we injected a single 20 mg/kg dose of DOX into AT1KO mice, wild type (WT) mice and WT mice treated with an AT1 antagonist, RNH-6270; to examine the role of AT1 in the chronic effects of DOX, we injected mice of the same groups with 1 mg/kg DOX once a week for 12 weeks. Echocardiography revealed that cardiac function was significantly impaired in WT mice, but not in AT1KO mice or WT mice administered RNH-6270, by both acute and chronic DOX treatment. Histological analysis showed that DOX induced myofibrillar loss and increased the number of apoptotic cells in WT mice, but not in AT1KO mice or WT mice administered RNH-6270. Expression of the ANP gene was downregulated by DOX treatment in WT mice, and this alteration was attenuated in AT1KO mice and in RNH-6270-treated mice. We conclude that the AT1-mediated Ang II signaling pathway plays an important role in DOX-induced cardiac impairment, suggesting that an AT1 antagonist can be used to prevent DOX-induced cardiomyopathy.

Green tea extracts can counteract the modification of fatty acid composition induced by doxorubicin in cultured cardiomyocytes

Doxorubicin cardiotoxicity is associated with the generation of free radicals, and involves not only lipid peroxidation but also a decreased biosynthesis of highly unsaturated fatty acids, leading to significant modification in cardiomyocyte fatty acid composition. We have evaluated whether naturally occurring antioxidants could counteract this side-effect. Green tea is an excellent source of catechins; we supplemented cultured rat cardiomyocytes with different green tea extracts to relate their catechin content and composition to their ability in protecting cells against doxorubicin-induced damage. The determination of total lipid fatty acid composition, of conjugated diene production (indicator of lipid peroxidation), and of lactate dehydrogenase release revealed that supplementation with tea extracts could counteract significant modifications in the fatty acyl pattern due to doxorubicin exposure, although to different extents. These differences could be ascribed to the different total catechin content and to qualitative differences among the tea extracts, determined by HPLC analysis.

Longitudinal evaluation of anthracycline cardiotoxicity by signal-averaged electrocardiography in children with cancer

BACKGROUND

The aim of the present study was to investigate the detection of anthracycline cardiotoxicity by signal-averaged electrocardiography (SAE) in children with cancer.

METHODS

There were 29 patients with a cumulative anthracycline (ATC) dose of 75-600 mg/m2. None of them had congestive heart failure. Patients underwent SAE just before (detection of chronic cardiotoxicity) and just after (detection of acute cardiotoxicity) ATC therapy. Echocardiography and Holter electrocardiography were performed at the same time. The rates of abnormal SAE, echocardiography, and electrocardiogram findings were calculated and compared for every 100 mg/m2 of ATC.

RESULTS

The SAE showed a significantly higher detection rate for acute cardiotoxicity was at a cumulative ATC dose of less than 400 mg/m2 when compared with other methods (P < 0.05). The lowest dose at which acute cardiotoxicity was detected by SAE was 117.3 mg/m2. The detection of chronic cardiotoxicity by SAE was significantly higher at a cumulative ATC dose of 100-400 mg/m2 when compared with other methods (P < 0.05), and the lowest value showing toxicity was 373.3 mg/m2. The lowest ATC dose causing chronic cardiotoxicity was significantly lower in patients less than 2-years-old (120.0 +/- 28.3 mg/m2) than in the other age groups (P < 0.05).

CONCLUSIONS

Acute and chronic ATC cardiotoxicity were detected by SAE at lower cumulative doses compared with other methods. The technique of SAE was a potentially useful method for detection of cardiotoxicity among those investigated and it provides useful information on subclinical cardiac dysfunction in patients receiving ATC therapy.

Treatment considerations for the elderly person with cancer

In an aging population, the number of patients with cancer continues to rise. Little research has focused on the treatment of cancer in the elderly. Therefore, the treatment for various cancers differs across the healthcare system. A uniform approach in assessing the elderly person with cancer is lacking. This article describes two case studies in the elderly population, focusing on two common cancers: acute myelogenous leukemia and breast cancer. Common side effects of treatment and determinants of treatment options are discussed. It is important that the elderly receive appropriate screening, early detection, treatment, and management of comorbidities.

Doxorubicin affects the cardiac muscarinic system in the rat

During the study on the mechanism of doxorubicin-induced cardiotoxicity, we observed that a long incubation (4 hr) with doxorubicin reduced the maximal negative inotropic effects of a muscarinic receptor agonist, carbachol. The mechanism responsible for this doxorubicin-induced reduction of the efficacy of carbachol was examined in isolated guinea pig hearts. In isolated left atrial muscle preparations, 1 hr incubation with 100 microM doxorubicin caused a parallel right-ward shift of the concentration-response curves for carbachol, but a longer (4 hr) incubation with this agent (30, 100 or 200 microM), caused a significant reduction of the magnitude of the negative inotropic effect of carbachol in addition to the concentration-dependent parallel right-ward shift. The 4-hr incubation with these concentrations of doxorubicin also reduced the maximal negative inotropic effect of an adenosine A1 receptor agonist, R-phenylisopropyl adenosine (R-PIA), without affecting the potency of this agonist. Doxorubicin (1 to 100 microM) reduced [3H]quinuclidinyl benzilate (QNB) binding in a concentration dependent manner, but failed to alter [3HIR-PIA binding. The decrease in the magnitude of the maximal negative inotropic effect by doxorubicin was caused by changes in the muscarinic system at steps common to the transduction of muscarinic and adenosine A1 receptor mechanisms.

Doxorubicin and mechanical performance of cardiac trabeculae after acute and chronic treatment: a review

Doxorubicin, a very potent and often used anti-cancer drug, has a wide spectrum of biological activity. Classic studies have demonstrated that doxorubicin and other members of the anthracycline family intercalate with DNA and partially uncoil the double-stranded helix. Doxorubicin has a high affinity for cell nuclei: as much as 60% of the total intracellular amount of doxorubicin is found in the nucleus. Once binding to DNA occurs, several consequences may ensue. The binding of anthracyclines to DNA inhibits DNA polymerase and nucleic acid synthesis. In addition, anthracyclines are known to stabilize the otherwise cleavable complex between DNA and homodimeric topoisomerase II enzyme subunits, resulting in the formation of protein-linked DNA double strand breaks. In tumor cells, these anthracycline-induced perturbations are believed to result in a final common pathway of endonucleolytic DNA fragmentation known as apoptosis. Because proliferation is an important determinant of tumor growth, interference with the genome is regarded as the primary cause of the anti-tumor action of doxorubicin. Intercalation with DNA may not be important in the cardiotoxicity associated with doxorubicin therapy (see next section), because cardiac cell proliferation in humans stops after 2 months of age. This review is focussed on the effects of doxorubicin on mechanical performance in skinned cardiac trabeculae after acute and chronic administration of doxorubicin. We look especially at the mechanical performance and the molecular changes observed and related to mechanical performance.

Anti-muscarinic actions of mitoxantrone in isolated heart muscles of guinea pigs

A hypotheses that mitoxantrone is a competitive antagonist at muscarinic cholinergic receptors was examined in guinea-pig hearts. In isolated left atrial muscle preparations, electrically paced at 2 Hz, the muscarinic agonist, carbachol, caused a concentration-dependent decrease in developed tension. Mitoxantrone caused a parallel right-ward shift of the concentration-response curve for carbachol. Schild plots for the effect of mitoxantrone on the carbachol concentration-response relationship were linear with a slope of 0.88 which was not significantly different from the unity. The right-ward shift of the carbachol concentration-response relationship by mitoxantrone significantly reversed after an additional incubation with a mitoxantrone-free solution, although the reversal was incomplete after a 2-h incubation in the mitoxantrone-free solution. Mitoxantrone caused a concentration-dependent displacement of specific [3H]quinuclidinyl benzilate binding to membrane preparations obtained from ventricular muscles of guinea-pig hearts. These results indicate that mitoxantrone acts as a competitive antagonist for the muscarinic receptors.

Effect of MEN 10755, a new disaccharide analogue of doxorubicin, on sarcoplasmic reticulum Ca(2+) handling and contractile function in rat heart

1. The use of anthraquinone antineoplastic agents is limited by their cardiac toxicity, which is largely due to activation of the sarcoplasmic reticulum (SR) Ca(2+) release channel (ryanodine receptor). MEN 10755 is a new disaccharide analogue of doxorubicin. We have evaluated its effects on SR function and its toxicity in isolated working rat hearts. 2. In rat SR vesicles, doxorubicin stimulated [(3)H]-ryanodine binding by increasing its Ca(2+)-sensitivity. At 1 microM Ca(2+), ryanodine binding increased by 15.3+/-2.5 fold, with EC(50)=20.6 microM. Epirubicin produced a similar effect, i.e. 9.7+/-0.6 fold stimulation with EC(50)=11.1 microM. MEN 10755 increased ryanodine binding by 1.9+/-0.3 fold (P:<0.01 vs doxorubicin and epirubicin), with EC(50)=38.9 microM. 3. Ca(2+)-induced Ca(2+) release experiments were performed by quick filtration technique, after SR loading with (45)Ca(2+). At 2 microM Ca(2+), doxorubicin (50 microM) increased the rate constant of Ca(2+) release to 82+/-5 s(-1) vs a control value of 22+/-2 s(-1) (P:<0.01), whereas 50 microM MEN 10755 did not produce any significant effect (24+/-3 s(-1)). 4. Ca(2+)-ATPase activity and (45)Ca(2+)-uptake were not significantly affected by doxorubicin, its 13-dihydro-derivative, epirubicin, MEN 10755 and the 13-dihydro-derivative of MEN 10755, at concentrations < or =100 microM. 5. In isolated heart experiments, administration of 30 microM doxorubicin or epirubicin caused serious contractile impairment, whereas 30 microM MEN 10755 produced only minor effects. 6. In conclusion, in acute experiments MEN 10755 was much less cardiotoxic than equimolar doxorubicin or epirubicin. This result might be accounted for by reduced activation of SR Ca(2+) release.

Cardiac systolic function before and after hematopoietic stem cell transplantation

In order to examine the effect of hematopoietic stem cell transplantation (HSCT) on cardiac systolic function, we measured left ventricular ejection fraction (LVEF) by radioventriculography (RVG) before and after the transplantation procedure. One hundred and forty-eight patients were examined, 96 undergoing allogeneic grafting and 52 autologous. Fifty patients had CML, 48 AML, 21 ALL, 18 multiple myeloma and 11 breast cancer. The second RVG examination was performed 22 to 227 days (median 60 days) after HSCT. The mean LVEF value in the whole patient group was 60.2% (range 39-81%) before and 61.1% (35-86%) after transplantation. Patients with CML had significantly higher LVEF before transplantation than patients with acute leukemia (P = 0.007) and multiple myeloma (P = 0.005). No significant changes in mean LVEF between the pre- and post-transplant measurements were seen in any of the diagnostic subgroups or in allogeneic or autologous recipients. None of the 148 patients in the study has shown any signs of clinical heart failure at 2, 5 to 10 years follow-up. Patients who had received anthracyclines in the previous treatment had significantly lower LVEF before transplantation but showed no increased risk of decline in cardiac function. In conclusion, the HSCT procedure does not seem to affect myocardial function 1-7 months after transplantation.

Molecular mechanism of doxorubicin-induced anticholinergic effect in guinea-pig atria

The molecular mechanisms of anticholinergic actions of doxorubicin were examined by electrophysiological methods in atria and myocytes isolated from guinea-pig heart. A direct anticholinergic action of doxorubicin was confirmed with antagonistic action on carbachol-induced negative inotropic effect in atria. Both carbachol and adenosine produced shortening of action potential duration in atria measured by a microelectrode method. Doxorubicin (10-100 µM) inhibited the carbachol-induced action potential shortening in a concentration-dependent manner. However, doxorubicin did not antagonize the shortening elicited by adenosine. The whole-cell voltage clamp technique was performed to induce the muscarinic acetylcholine-receptor-operated K+ current (IK.ACh) in atrial myocytes loaded with GTP or GTPgammaS, a nonhydrolysable analogue of GTP. Doxorubicin (1-100 µM) suppressed carbachol-induced IK.ACh in a concentration-dependent manner (IC50 = 5.6 µM). In contrast, doxorubicin (10 and 100 µM) suppressed neither adenosine-induced IK.ACh nor GTPgammaS-induced IK.ACh. These results indicate that doxorubicin produces a direct anticholinergic effect through the muscarinic receptors in atrial myocytes.Key words: action potential duration, anticholinergic action, atrial cell, doxorubicin, the muscarinic acetylcholine-receptor-operated K+ current.

Anthracycline-induced cardiomyopathy

Anthracycline cardiomyopathy is less frequently encountered nowadays, due to the well-recognised dose limitations and cardiac monitoring protocols used by chemotherapy centres. However, it is a condition that will persist due to the sensitivity of some patients to these drugs and the necessity for large doses to be used for certain individuals. We have demonstrated the benefit of angiotensin-converting enzyme inhibitor therapy and would consider introducing these compounds at the earliest opportunity. The use of probucol and vitamins as antioxidants capable of preventing the onset of cardiomyopathy in humans appears to require further investigation but may significantly reduce the incidence of this condition in the future.

The high-dose sequential (Milan) chemotherapy/PBSC transplantation regimen for patients with lymphoma is not cardiotoxic

BACKGROUND

The high-dose sequential (HDS) regimen developed in Milan for high-grade lymphomas is very active, but its toxicities are still partly unknown. We evaluated prospectively by doppler-echocardiography the cardiotoxicity of this treatment.

PATIENTS AND METHODS

Over seven weeks, 20 patients received a sequence of cyclophosphamide, methotrexate, etoposide, mitoxantrone and melphalan, each at its maximum tolerable dose, and the latter in conjunction with autologous peripheral stem-cell transplantation. Echocardiography was performed at baseline, before administration of mitoxantrone and 2, 6 and 12 months after transplantation. The following parameters of the left ventricular systolic and diastolic functions were determined: end diastolic (LVD) and end systolic (LVS) dimensions, the ejection fraction (EF), and the Doppler derived diastolic parameters: peak velocity of the early (E) and late (A) transmitral flow, the E:A ratio, deceleration time of the E wave (DT) and isovolumetric relaxation time (IVRT). A group of 20 normal volunteers served as control.

RESULTS

At baseline, in comparison to controls, the patients had altered diastolic function (diminished E:A ratio) and, although still within the normal range, a slightly reduced systolic function (EF). During treatment or in the course of follow-up none of the patients showed clinical signs or symptoms of cardiac failure, nor significant changes of systolic or diastolic parameters, apart from a transient increase in the E:A ratio after the first three chemotherapy cycles (from 1.14 to 1.37, P < 0.05). The EF remained constant during, and up to six months after, transplantation, decreasing only slightly after one year (from 62% to 59%, P < 0.05). Using analysis of covariance we showed that the major determinants of baseline cardiac function and of its evolution over time were patient age and gender, with previous treatment with anthracyclines having a minor role.

CONCLUSIONS

The HDS chemotherapy regimen produced no significant sign of cardiotoxicity up to one year after transplantation in patients with normal baseline cardiac function and no history of cardiac disease, pretreated with up to 550 mg/m2 of doxorubicin.

Binding of adriamycin to liposomes as a probe for membrane lateral organization

A stopped-flow spectrofluorometer equipped with a rapid scanning emission monochromator was utilized to monitor the binding of adriamycin to phospholipid liposomes. The latter process is evident as a decrease in fluorescence emission from a trace amount of a pyrene-labeled phospholipid analog (PPDPG, 1-palmitoyl-2-[(6-pyren-1-yl)]decanoyl-sn-glycero-3-phospho-rac-++ +glyce rol) used as a donor for resonance energy transfer to adriamycin. For zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes, fluorescence decay was slow, with a half-time t1/2 of approximately 2 s. When the mole fraction of the acidic phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol (POPG), was increased to XPG >/= 0.04, the decay of fluorescence became double exponential, and an additional, significantly faster process with t1/2 in the range between 2 and 4 ms was observed. Subsequently, as XPG was increased further, the amplitude of the fast process increased, whereas the slower process was attenuated, its t1/2 increasing to 20 s. Increasing [NaCl] above 50 mM or [CaCl2] above 150 microM abolished the fast component, thus confirming this interaction to be electrostatic. The critical dependence of the fast component on XPG allows the use of this process to probe the organization of acidic phospholipids in liposomes. This was demonstrated with 1, 2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes incorporating PPDPG (XPPDPG = 0.03), i.e., conditions where XPG in fluid bilayers is below the required threshold yielding the fast component. In keeping with the presence of clusters of PPDPG, the fast component was observed for gel-state liposomes. At approximately 34 degreesC (i.e., 6 degrees below Tm), the slower fluorescence decay also appeared, and it was seen throughout the main phase transition region as well as in the liquid-crystalline state. The fluorescence decay behavior at temperatures below, above, and at the main phase transition temperature is interpreted in terms of thermal density fluctuations and an intermediate state between gel and liquid-crystalline states being involved in the phospholipid main phase transition. This is the first observation of a cluster constituted by acidic phospholipids controlling the membrane association of a drug.

Elevated B-type natriuretic peptide levels after anthracycline administration

BACKGROUND

Cardiotoxicity leading to congestive heart failure is a complication of the anthracyclines. Biochemical methods to diagnose and monitor cardiac function after anthracycline administration would be most useful. We examined the diagnostic role of B-type natriuretic peptide (BNP), a potent biochemical marker of left ventricular dysfunction, in patients administered anthracyclines.

METHODS

Twenty-seven consecutive patients receiving anthracyclines were investigated by serial measurements of BNP levels and other cardiac neurohormones (A-type natriuretic peptide, renin, aldosterone, angiotensin II, norepinephrine, and epinephrine) and myocardial markers (creatine kinase-MB and myosin light chain). Echocardiography was done to assess systolic (ejection fraction) and diastolic (mitral inflow A/E ratio) functions.

RESULTS

Of the examined cardiac biochemical markers, BNP levels alone showed marked elevations to abnormal levels after anthracycline administration. Most patients showed transient increases (peak at 3 to 7 days). Patients with persistent elevations showed a poor prognosis. A/E ratio also correlated with increases in BNP levels in selected patients, which may suggest that raised BNP levels are reflective of induced diastolic dysfunction.

CONCLUSIONS

Our studies suggest the possible use of BNP levels to assess the cardiac state after anthracycline administration. BNP levels most likely reflect cardiac tolerance to the cardiotoxic agent. Serial BNP profiles also suggest persistent elevations to be associated with potentially decompensatory states in contrast to tolerable transient increases. Diagnosis of degree of cardiac tolerance by response to drug administration may be analogous to use of stress testing (exercise) to help define underlying left ventricular dysfunction.

Curcumin attenuation of acute adriamycin myocardial toxicity in rats

The protective effect of curcumin on acute adriamycin (ADR) myocardial toxicity was analysed in rats. ADR toxicity, induced by a single intraperitoneal injection (30 mg kg(-1)), was revealed by elevated serum creatine kinase (CK) and lactate dehydrogenase (LDH). The level of the lipid peroxidation products, conjugated dienes and malondialdehyde, was markedly elevated by ADR. ADR caused a decrease in myocardial glutathione content and glutathione peroxidase activity. In contrast, cardiac catalase activity was increased in ADR rats. Curcumin treatment (200 mg kg(-1), seven days before and two days following ADR) significantly ameliorated the early manifestation of cardiotoxicity (ST segment elevation and an increase in heart rate) and prevented the rise in serum CK and LDH exerted by ADR. ADR rats that received curcumin displayed a significant inhibition of lipid peroxidation and augmentation of endogenous antioxidants. These results suggest that curcumin inhibits ADR cardiotoxicity and might serve as novel combination chemotherapeutic agent with ADR to limit free radical-mediated organ injury.

The secondary alcohol metabolite of doxorubicin irreversibly inactivates aconitase/iron regulatory protein-1 in cytosolic fractions from human myocardium

Anticancer therapy with doxorubicin (DOX) is limited by severe cardiotoxicity, presumably reflecting the intramyocardial formation of drug metabolites that alter cell constituents and functions. In a previous study, we showed that NADPH-supplemented cytosolic fractions from human myocardial samples can enzymatically reduce a carbonyl group in the side chain of DOX, yielding a secondary alcohol metabolite called doxorubicinol (DOXol). Here we demonstrate that DOXol delocalizes low molecular weight Fe(II) from the [4Fe-4S] cluster of cytoplasmic aconitase. Iron delocalization proceeds through the reoxidation of DOXol to DOX and liberates DOX-Fe(II) complexes as ultimate by-products. Under physiologic conditions, cluster disassembly abolishes aconitase activity and forms an apoprotein that binds to mRNAs, coordinately increasing the synthesis of transferrin receptor but decreasing that of ferritin. Aconitase is thus converted into an iron regulatory protein-1 (IRP-1) that causes iron uptake to prevail over sequestration, forming a pool of free iron that is used for metabolic functions. Conversely, cluster reassembly converts IRP-1 back to aconitase, providing a regulatory mechanism to decrease free iron when it exceeds metabolic requirements. In contrast to these physiologic mechanisms, DOXol-dependent iron release and cluster disassembly not only abolish aconitase activity, but also affect irreversibly the ability of the apoprotein to function as IRP-1 or to reincorporate iron within new Fe-S motifs. This damage is mediated by DOX-Fe(II) complexes and reflects oxidative modifications of -SH residues having the dual role to coordinate cluster assembly and facilitate interactions of IRP-1 with mRNAs. Collectively, these findings describe a novel mechanism of cardiotoxicity, suggesting that intramyocardial formation of DOXol may perturb the homeostatic processes associated with cluster assembly or disassembly and the reversible switch between aconitase and IRP-1. These results may also provide a guideline to design new drugs that mitigate the cardiotoxicity of DOX.

Does the multidrug-resistance modulator cyclosporin A increase the cardiotoxicity of high-dose anthracycline chemotherapy?

Cyclosporin A has heterogeneous effects on anthracycline-related cardiotoxicity and can prevent multidrug-resistance (MDR). The aim of this study was to explore whether the coadministration of cyclosporin A is accompanied by an increase in cardiotoxicity. Forty-three patients (27 male, 16 female, age: 18-67 yrs [mean: 47.5 yrs, SD: 11.6 yrs]) received 177 radionuclide ventriculography examinations (RNV 177 at rest, 133 at stress) before and during chemotherapy with either doxorubicin (n = 23) or epirubicin (n = 20). RNV studies were applied up to 11 times in the follow-up of the patients. A maximum of 10 courses of chemotherapy was performed. In the doxorubicin group only, the age of the patients and the cumulative dose of the chemotherapeutic agent had a significant negative impact on left ventricular ejection fractions, whereas cyclosporin A had a significant positive influence (multiple analysis of regression, p < 0.05). Cyclosporin A did not cause any significant increase in cardiotoxicity in our patients.

Ca2+ overloading causes the negative inotropic effect of doxorubicin in myocytes isolated from guinea-pig hearts

We reported previously that conditions shown to increase Ca2+ loading augment the negative inotropic effect of doxorubicin: To examine if the negative inotropic effect is caused by Ca2+ overloading doxorubicin-induced changes in diastolic and systolic Ca2+ concentrations and twitch contractions were studied under altered Ca2+ loading. Intracellular Ca2+ concentrations ([Ca2+]i) were monitored in fura-2-loaded myocytes isolated from the ventricular muscle of guinea-pig hearts. Twitch contractions were estimated from the shortening of myocytes. In myocytes incubated at 34 degrees C a medium containing 1.2 mM CaCl2 (standard conditions), doxorubicin (100 microM) caused a significant decrease in diastolic length, and an increase in the amplitude of contraction. The positive inotropic effect of doxorubicin was followed by a negative effect. Concomitant with these changes in myocyte contractions, a monophasic increase in diastolic Ca2+ and an increase and a subsequent decrease in the amplitude of Ca2+ transients (peak [Ca2+]i minus diastolic [Ca2+]i) were observed. When the Ca2+ load of myocytes was increased by an incubation at a low temperature (25 degrees C) or in the presence of high Ca2+ in the incubation medium (2.4 mM CaCl2), diastolic [Ca2+]i was elevated. Doxorubicin further increased diastolic [Ca2+]i. Under these conditions, the doxorubicin-induced increase in the twitch contraction lasted a shorter period of time and the subsequent decrease in contraction was significantly enhanced. The peak [Ca2+]i initially increased slightly and then decreased. Thus, the decrease in the amplitude of Ca2+ transients, as well as myocyte contraction was greater compared to the corresponding values observed under the standard conditions. These changes in the contraction and Ca2+ transient developed with the same time course. The effects of the low temperature incubation were antagonized by verapamil. These results indicate that the negative inotropic effect of doxorubicin results from a decrease in the amplitude of Ca2+ transients caused by an increased diastolic [Ca2+]i and a decreased peak [Ca2+]i. These changes are likely to be caused by myocardial Ca2+ overload.

Doxorubicin-induced acute changes in cytotoxic aldehydes, antioxidant status and cardiac function in the rat

Doxorubicin (DOX)-induced cardiotoxicity is thought to be caused by free radical-mediated mechanisms. An in vivo rat model was developed to investigate the DOX-induced cascade of early biochemical changes focusing on the central role of the aldehydic lipid peroxidation products. Antioxidant status was evaluated by glutathione measurements. Creatine Kinase (CK) activity was measured as an index of cardiac injury. Development of functional abnormalities were documented by echocardiography. The results showed that aldehydes in rat plasma and heart tissues increased significantly following DOX treatment. The changes occurred early, peaked around 2 h after DOX administration, and the levels declined or returned to baseline value within 8-24 h. Toxic aldehyde levels including malondialdehyde, hexanal and 4-hydroxy-non-2-enal also increased. Acyloin levels, metabolic products of aldehydes, increased early and then decreased in plasma, and there was a significant decrease in heart tissues after DOX treatment. GSH levels decreased early, then increased by 24 h, while GSSG levels decreased initially, then increased after DOX treatment, suggesting early depletion of GSH and a later rebound phenomenon. CK levels were elevated after treatment. The functional abnormalities were documented by stress echocardiography in some rats although the changes were not consistent at such an early stage following treatment. Our data confirmed the involvement of free radicals, and suggested that the cytotoxic aldehydes play a central role in initiating the steps that lead to functional impairment of the myocardium following DOX administration. Scavengers and the metabolic removal of some of the aldehydes also play a role in protecting the myocardium against injury.

Paradoxical inhibition of cardiac lipid peroxidation in cancer patients treated with doxorubicin. Pharmacologic and molecular reappraisal of anthracycline cardiotoxicity

Anticancer therapy with doxorubicin (DOX) and other quinone anthracyclines is limited by severe cardiotoxicity, reportedly because semiquinone metabolites delocalize Fe(II) from ferritin and generate hydrogen peroxide, thereby promoting hydroxyl radical formation and lipid peroxidation. Cardioprotective interventions with antioxidants or chelators have nevertheless produced conflicting results. To investigate the role and mechanism(s) of cardiac lipid peroxidation in a clinical setting, we measured lipid conjugated dienes (CD) and hydroperoxides in blood plasma samples from the coronary sinus and femoral artery of nine cancer patients undergoing intravenous treatments with DOX. Before treatment, CD were unexpectedly higher in coronary sinus than in femoral artery (342 +/- 131 vs 112 +/- 44 nmol/ml, mean +/- SD; P < 0.01), showing that cardiac tissues were spontaneously involved in lipid peroxidation. This was not observed in ten patients undergoing cardiac catheterization for the diagnosis of arrhythmias or valvular dysfunctions, indicating that myocardial lipid peroxidation was specifically increased by the presence of cancer. The infusion of a standard dose of 60 mg DOX/m(2) rapidly ( approximately 5 min) abolished the difference in CD levels between coronary sinus and femoral artery (134 +/- 95 vs 112 +/- 37 nmol/ml); moreover, dose fractionation studies showed that cardiac release of CD and hydroperoxides decreased by approximately 80% in response to the infusion of as little as 13 mg DOX/m(2). Thus, DOX appeared to inhibit cardiac lipid peroxidation in a rather potent manner. Corollary in vitro experiments were performed using myocardial biopsies from patients undergoing aortocoronary bypass grafting. These experiments suggested that the spontaneous exacerbation of lipid peroxidation probably involved preexisting Fe(II) complexes, which could not be sequestered adequately by cardiac isoferritins and became redox inactive when hydrogen peroxide was included to simulate DOX metabolism and hydroxyl radical formation. Collectively, these in vitro and in vivo studies provide novel evidence for a possible inhibition of cardiac lipid peroxidation in DOX-treated patients. Other processes might therefore contribute to the cardiotoxicity of DOX.

A new protocol (MiCEP) for the treatment of intermediate or high-grade non-Hodgkin's lymphoma in the elderly

Age has proved to be an important prognostic factor in patients with advanced non-Hodgkin lymphoma (NHL) and these patients require intensive and extensive therapy. Dose-reduction and therapy attenuation have reduced treatment-related toxicity, but have also decreased therapeutic efficacy. Between January 1990 and December 1992, 41 previously untreated patients, 65 years with stage 2-4 intermediate- or high-grade NHL were treated with a new therapeutic scheme which included Mitoxantrone, Etoposide, Cyclophosphamide and Prednisone (MiCEP). Twenty-eight patients achieved a complete remission, ten patients partial remission (overall response rate of 93%) and two cases were resistant. The overall survival was 66% with a median follow-up of 24 months from diagnosis: three patients relapsed after a median period of 7 months. The relapse-free survival was 92% after a median follow-up of 18 months. Blood and other organ toxicity was acceptable and 12% of patients experienced a grade 4 (WHO) neutropenia. In conclusion, MiCEP was effective in inducing a good remission rate with moderate toxic effects in elderly patients with intermediate- or high-grade NHL and appears to be a useful combination to use in this group of patients.

Doxorubicin-induced cardiac neurotoxicity: study with iodine 123-labeled metaiodobenzylguanidine scintigraphy

BACKGROUND

Iodine 123-labeled metaiodobenzylguanidine (123I-MIBG) can be used to generate a scintigraphic image of the adrenergic nervous innervation of the heart.

METHODS AND RESULTS

To test the hypothesis that doxorubicin may lead to damage of cardiac neurons, we examined 37 patients with various malignant neoplasms, 14 of whom were on therapy with doxorubicin. All patients were examined with 123I-MIBG scintigraphy and radionuclide ventriculography. Cardiac 123I-MIBG uptake was assessed by means of a heart to mediastinum activity ratio (H/M). Left ventricular ejection fraction was not different in patients with or without doxorubicin. In patients receiving doxorubicin, the H/M ratio was significantly lower (1.73 +/- 0.25 vs 2.13 +/- 0.25, p < 0.001) and correlated with doxorubicin cumulative dose (r = -0.51, p < 0.001). By using a H/M ratio of 1.73 as a cutoff point, 123I-MIBG uptake was abnormal in none of the 23 patients not receiving and 6 of 14 patients receiving doxorubicin therapy (p < 0.001). In 10 patients initially not receiving doxorubicin, 123I-MIBG scintigraphy was repeated after receiving 236 +/- 47 mg/m2 of doxorubicin. The H/M became abnormal in 3 of 10 patients, whereas the ejection fraction became abnormal in 2 of 10 patients.

CONCLUSION

123I-MIBG cardiac uptake decreases in a doxorubicin dose-dependent way, indicating a cardiac adrenergic neurotoxic effect of doxorubicin. This phenomenon appears early and generally before deterioration of the ejection fraction.

Cardiac troponin T and creatine kinase MB mass concentrations in children receiving anthracycline chemotherapy

Anthracyclines (doxorubicin, daunorubicin, and derivatives) are among the most effective antineoplastic drugs for pediatric cancer with dose-limiting acute and long-term cardiotoxicity. The exact mechanism of the development of cardiomyopathy is still not clear. Anthracyclines may induce subclinical acute myocardial injury leading to lysis of a limited number of myocytes. Alternatively, myocytes may experience a transient loss of cytoplasmic membrane integrity. Both conditions may lead to a transient efflux of small amounts of cytoplasmic enzymes and other proteins specific to the heart muscle fibers. To test these hypotheses we assayed plasma creatine kinase (CK) MB mass and cardiac specific troponin T (TnT). CKMB may be released even in case of reversible cell membrane injury, while prolonged elevation of TnT is the most sensitive and specific marker of limited myocardial necrosis. Thirty-five anthracycline-containing chemotherapy courses in 22 children with cancer were analyzed. CKMB mass and TnT concentrations were within the normal range in all children before anthracycline therapy. Within 72 hours from anthracycline therapy no increment of one of these two marker proteins was detected (ANOVA for repeated measures, P = 0.94 [TnT] and 0.25 [CKMB]). We conclude that only minimal if any acute necroses of cardiac myocytes occur after anthracycline therapy. Even membrane integrity appears to be maintained within the first 3 days after anthracycline therapy, in the absence of electrocardiographic or echocardiographic signs of acute cardiotoxicity.