Acute cardiotoxicity after initiation of the novel tyrosine kinase inhibitor gilteritinib for acute myeloid leukemia

BACKGROUND

Gilteritinib is a novel FMS-like tyrosine kinase 3 inhibitor recently approved by the United States Food and Drug Administration in 2018 for relapsed or refractory acute myeloid leukemia. However, gilteritinib may be associated with underrecognized cardiotoxicities.

CASE PRESENTATION

This case describes a patient with a history significant for hyperlipidemia who was diagnosed with relapsed acute myeloid leukemia. After four doses of gilteritinib monotherapy, she abruptly developed acute systolic heart failure with global hypokinesis and septal wall motion abnormalities. Two days after discontinuation, cardiac magnetic resonance imaging showed partial recovery of her left ventricular ejection fraction as well as myocardial edema and non-ischemic fibrosis suggestive of inflammatory cardiomyopathy. She underwent intravenous diuresis and eventually started guideline-directed heart failure therapy. Follow-up cardiac magnetic resonance imaging five months later showed improved ejection fraction with mild non-ischemic fibrosis and resolution of myocardial edema and inflammation. She later received an allogeneic stem cell transplant from a matched unrelated donor.

CONCLUSIONS

Gilteritinib may be associated with early cardiotoxicities, including non-ischemic cardiomyopathy and myocarditis. Cardiac magnetic resonance imaging can be an important modality to help differentiate or diagnose early cardiotoxicities associated with novel targeted therapies.

Early toxicity and clinical outcomes after chimeric antigen receptor T-cell (CAR-T) therapy for lymphoma

BACKGROUND

Chimeric antigen receptor T-cell (CAR-T) infusion is associated with early toxicity. Yet, whether early toxicity development holds ramifications for long-term outcomes is unknown.

METHODS

From a large cohort of consecutive adult patients treated with CAR-T therapies for relapsed or refractory lymphomas from 2016 to 2019, we assessed progression-free survival (PFS), by toxicity development (cytokine release syndrome (CRS), neurotoxicity, or cardiotoxicity]. We also assessed the relationship of toxicity development to objective disease response, and overall survival (OS). Multivariable regression was utilized to evaluate relationships between standard clinical and laboratory measures and disease outcomes. Differences in outcomes, by toxicity status, were also assessed via 30-day landmark analysis. Furthermore, we assessed the effects of early anti-CRS toxicity therapy use (at ≤grade 2 toxicity) on maximum toxicity grade observed, and long-term disease outcomes (PFS and OS).

RESULTS

Overall, from 102 CAR-T-treated patients, 90 were identified as treated with single-agent therapy, of which 88.9% developed toxicity (80 CRS, 41 neurotoxicity, and 17 cardiotoxicity), including 28.9% with high-grade (≥3) events. The most common manifestations were hypotension at 96.6% and fever at 94.8%. Among patients with cardiac events, there was a non-significant trend toward a higher prevalence of concurrent or preceding high-grade (≥3) CRS. 50.0% required tocilizumab or corticosteroids. The median time to toxicity was 3 days; high grade CRS development was associated with cardiac and neurotoxicity. In multivariable regression, accounting for disease severity and traditional predictors of disease response, moderate (maximum grade 2) CRS development was associated with higher complete response at 1 year (HR: 2.34; p=0.07), and longer PFS (HR: 0.41; p=0.02, in landmark analysis), and OS (HR: 0.43; p=0.03). Among those with CRS, relative blood pressure (HR: 2.25; p=0.004), respectively, also associated with improved PFS. There was no difference in disease outcomes, or maximum toxicity grade (CRS, neurotoxicity, or cardiotoxicity) observed, based on the presence or absence of the use of early CRS-directed therapies.

CONCLUSIONS

Among adult lymphoma patients, moderate toxicity manifest as grade 2 CRS after CAR-T infusion may associate with favorable clinical outcomes. Further studies are needed to confirm these findings.

Cardiovascular Toxicities of Androgen Deprivation Therapy

OPINION STATEMENT

Prostate cancer is the second leading cause of cancer death in men, and cardiovascular disease is the number one cause of death in patients with prostate cancer. Androgen deprivation therapy, the cornerstone of prostate cancer treatment, has been associated with adverse cardiovascular events. Emerging data supports decreased cardiovascular risk of gonadotropin releasing hormone (GnRH) antagonists compared to agonists. Ongoing clinical trials are assessing the relative safety of different modalities of androgen deprivation therapy. Racial disparities in cardiovascular outcomes in prostate cancer patients are starting to be explored. An intriguing inquiry connects androgen deprivation therapy with reduced risk of COVID-19 infection susceptibility and severity. Recognition of the cardiotoxicity of androgen deprivation therapy and aggressive risk factor modification are crucial for optimal patient care.

Clinical impact of interruption in adjuvant Trastuzumab therapy in patients with operable HER-2 positive breast cancer

BACKGROUND

Trastuzumab-induced cardiotoxicity (TIC) can lead to early discontinuation of adjuvant therapy, however there is limited evidence on long-term survival outcomes in patients with operable human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) experiencing treatment interruption or discontinuation.

METHODS

The primary objective of the study was to evaluate disease-free survival (DFS) in non-metastatic, HER2-positive, female BC patients who experienced treatment interruption or early discontinuation of trastuzumab therapy. Clinical and histopathological data were collected on 400 patients at The Ohio State University, an NCI-designated comprehensive cancer center between January 2005 and December 2015. Treatment interruption was defined as any delay of ≥2 weeks during trastuzumab therapy, including permanent cessation prior to completing planned therapy. TIC was defined as LVEF < 50% or > 15 points decline from baseline as evaluated by 2D echocardiogram after initiation of (neo) adjuvant therapy. DFS was defined as the time from diagnosis to first recurrence (loco-regional or distant recurrence) including second primary BC or death. Overall survival (OS) was defined as the time from diagnosis to death or last known follow up. OS/DFS estimates were generated using Kaplan-Meier methods and compared using Log-rank tests. Cox proportional hazard models were used to calculate adjusted hazard ratios (aHR) for OS/DFS.

RESULTS

A total of 369 patients received trastuzumab therapy; 106 (29%) patients experienced treatment interruption at least once and 42 (11%) permanently discontinued trastuzumab prior to completing planned therapy. TIC was the most common reason for interruption (66 patients, 62%). The median duration of trastuzumab in patients with treatment interruption was 11.3 months (range: 0.5-16.9) with 24 (23%) patients receiving ≤6 months of therapy. This duration includes the time delay related to treatment interruption. Patients with any treatment interruption had worse DFS (aHR: 4.4, p = 0.001) and OS (aHR: 4.8, p < 0.001) after adjusting for age, stage, grade, ER, node status and TIC.

CONCLUSIONS

Treatment interruption or early discontinuation of trastuzumab therapy in early HER2-positive BC, most often from TIC, is an independent prognostic marker for worse DFS and OS in operable HER2-positive BC. Future prospective studies should consider targeting at-risk populations and optimizing cardiac function to avoid interruption in trastuzumab therapy.

Contemporary Understandings of Cardiovascular Disease After Cancer Radiotherapy: a Focus on Ischemic Heart Disease

PURPOSE OF REVIEW

Radiation-induced cardiovascular disease, including coronary artery disease, is a well-known sequela of radiation therapy and represents a significant source of morbidity and mortality for cancer survivors. This review examines current literature and guidelines to care for this growing population of cancer survivors.

RECENT FINDINGS

The development of radiation-induced ischemic heart disease following radiation can lead even to early cardiotoxicities, inclusive of coronary artery disease, which limit cancer treatment outcomes. These coronary lesions tend to be diffuse, complex, and proximal. Early detection with multimodality imaging and targeted intervention is required to minimize these risks. Early awareness, detection, and management of radiation-induced cardiovascular disease are paramount as cancer survivorship continues to grow.

Resource and Infrastructure-Appropriate Management of ST-Segment Elevation Myocardial Infarction in Low- and Middle-Income Countries

The 143 low- and middle-income countries (LMICs) of the world constitute 80% of the world's population or roughly 5.86 billion people with much variation in geography, culture, literacy, financial resources, access to health care, insurance penetration, and healthcare regulation. Unfortunately, their burden of cardiovascular disease in general and acute ST-segment-elevation myocardial infarction (STEMI) in particular is increasing at an unprecedented rate. Compounding the problem, outcomes remain suboptimal because of a lack of awareness and a severe paucity of resources. Guideline-based treatment has dramatically improved the outcomes of STEMI in high-income countries. However, no such focused recommendations exist for LMICs, and the unique challenges in LMICs make directly implementing Western guidelines unfeasible. Thus, structured solutions tailored to their individual, local needs, and resources are a vital need. With this in mind, a multicountry collaboration of investigators interested in LMIC STEMI care have tried to create a consensus document that extracts transferable elements from Western guidelines and couples them with local realities gathered from expert experience. It outlines general operating principles for LMICs focused best practices and is intended to create the broad outlines of implementable, resource-appropriate paradigms for management of STEMI in LMICs. Although this document is focused primarily on governments and organizations involved with improvement in STEMI care in LMICs, it also provides some specific targeted information for the frontline clinicians to allow standardized care pathways and improved outcomes.

Venous thromboembolism in cancer patients: risk assessment, prevention and management

Thrombosis and thromboembolic events contribute to significant morbidity in cancer patients. Venous thrombosis embolism (which includes deep vein thrombosis and pulmonary embolism) accounts for a large percentage of thromboembolic events. Appropriate identification of cancer patients at high risk for venous thromboembolism and management of thromboembolic event is crucial in improving the quality of care for cancer patients. However, thromboembolism in cancer patients is a complex problem and the management has to be tailored to each individual. The focus of this review is to understand the complex pathology, physiology and risk factors that drive the process of venous thrombosis and embolism in cancer patients and the current guidelines in management.

Fibrillary glomerulopathy in a 10-year-old female

A 10-year-old African-American female was evaluated for asymptomatic proteinuria. Initial investigation did not reveal the etiology of her renal disease. She subsequently underwent a percutaneous renal biopsy, which was consistent with fibrillary glomerulopathy. This condition is rare in children and is identified histologically by a solid, randomly arranged, amyloid-like fibrillar structure with a diameter of about 18-22 nm. It is a diagnosis of exclusion, the clinical presentation of which can be quite varied. Children usually present with nephrotic syndrome. There is no effective therapy for this condition. Therapy with steroids, cytotoxic agents, and plasmapheresis does not confer any real benefit in stabilizing or improving renal function. However, angiotensin converting enzyme inhibitors can decrease the proteinuria. End-stage renal disease is known to occur in 50% of patients within 4 years of diagnosis. The nephrotic-range proteinuria in our patient significantly decreased during a 4-year follow-up without any therapy, while maintaining normal renal function.

Reactive oxygen species mediate amplitude-dependent hypertrophic and apoptotic responses to mechanical stretch in cardiac myocytes

Oxidative stress stimulates both growth and apoptosis in cardiac myocytes in vitro. We investigated whether oxidative stress mediates hypertrophy and apoptosis in cyclically stretched ventricular myocytes. Neonatal rat ventricular myocytes cultured on laminin-coated silastic membranes were stretched cyclically (1 Hz) at low (nominal 5%) and high (nominal 25%) amplitudes for 24 hours. Stretch caused a graded increase in superoxide anion production as assessed by superoxide dismutase (SOD)-inhibitable cytochrome c reduction or electron paramagnetic resonance spectroscopy. The role of reactive oxygen species (ROS) was assessed using the cell-permeable SOD/catalase mimetics Mn(II/III)tetrakis(1-methyl-4-peridyl) (MnTMPyP) and EUK-8. Stretch-induced increases in protein synthesis ((3)H-leucine incorporation) and cellular protein content were completely inhibited by MnTMPyP (0.05 mmol/L) at both low and high amplitudes of stretch. In contrast, while MnTMPyP inhibited basal atrial natriuretic factor (ANF) mRNA expression, the stretch-induced increase in ANF mRNA expression was not inhibited by MnTMPyP. In contrast to hypertrophy, only high-amplitude stretch increased myocyte apoptosis, as reflected by increased DNA fragmentation on gel electrophoresis and an approximately 3-fold increase in the number of TUNEL-positive myocytes. Similarly, only high-amplitude stretch increased the expression of bax mRNA. Myocyte apoptosis and bax expression stimulated by high-amplitude stretch were inhibited by MnTMPyP. Both low- and high-amplitude stretch caused rapid phosphorylation of ERK1/2, while high-, but not low-, amplitude stretch caused phosphorylation of JNKs. Activation of both ERK1/2 and JNKs was ROS-dependent. Thus, cyclic strain causes an amplitude-related increase in ROS, associated with differential activation of kinases and induction of hypertrophic and apoptotic phenotypes.

Kinetic consequences of covalent linkage of DNA binding polyamides

Polyamides composed of N-methylpyrrole (Py) and N-methylimidazole (Im) subunits can bind in the minor groove of DNA at predetermined sequences with subnanomolar affinity and high specificity. Covalent linkage of polymer subunits using a gamma-aminobutyric acid linker has been shown to increase both the affinity and specificity of polyamides. Using a fluorescence detected stopped-flow assay, we have studied the differences in association and dissociation kinetics of a series of polyamides representing unlinked, hairpin and cyclic analogues of the four ring polyamide ImPyPyPy-beta-Dp. Whereas the large differences seen in the equilibrium association constants between the unlinked and covalently linked polyamides are primarily due to higher association rate constants, discrimination between matched and mismatched sites by each polyamide can be ascribed in large part to differences in their dissociation rate constants. The consequences of this kinetic behavior for future design are discussed.

Cytochrome P-450 as a source of catalytic iron in minimal change nephrotic syndrome in rats

We have recently demonstrated an important pathogenic role for glomerular catalytic iron in the puromycin aminonucleoside (PAN) induced minimal change nephrotic syndrome (MCNS). The source of this iron capable of catalyzing free radical reactions is not known. We examined the role of cytochrome P-450 (CYP) as a source of catalytic iron in a model MCNS induced by single injection of PAN to rats. Treatment of PAN resulted in a marked increase in the catalytic iron associated with significant loss of glomerular CYP content. Administration of CYP inhibitors significantly prevented the injury-induced loss of CYP content and the increase in the catalytic iron in the glomeruli accompanied by a marked decrease in proteinuria. In an in vitro study utilizing glomerular epithelial cells (GEC), CYP inhibitors also markedly prevented the PAN-induced increase in the catalytic iron and hydroxyl radical formation accompanied by significant protection against PAN-induced cytotoxicity. Taken together our data indicate that the CYP, a group of heme protein, may serve as a significant source of this catalytic iron.

Effect of iron chelator, hydroxyl radical scavenger and cytochrome P450 inhibitors on the cytotoxicity of cisplatin to tumor cells

BACKGROUND

Iron catalyzed reactive oxygen metabolites (ROM) are important mediators in cisplatin (CP)-induced nephrotoxicity, and cytochrome P450 (CYP) is the major source of this iron. Iron chelators, hydroxyl radical scavengers and CYP inhibitors have shown marked protection.

MATERIAL AND METHODS

This study was designed to determine whether these agents affect the tumoricidal efficacy of CP to LLC-WRC 256 tumor cells.

RESULTS

CP was cytotoxic to the tumor cells in a dose and time dependent manner. Iron chelator, hydroxyl radical scavenger and CYP inhibitors did not reduce the cytotoxic effect of CP. Exposure of the tumor cells to CP did not increase the catalytic iron release and the generation of hydroxyl radical. Both CYP activity and content in the tumor cells were less than 10% of that in the rat liver.

CONCLUSION

We speculate that iron chelator, hydroxyl radical scavenger and CYP inhibitors do not alter the antitumor efficacy of CP.

On the kinetics of distamycin binding to its target sites on duplex DNA

Distamycin A is a well known polyamide antibiotic that can bind in the minor groove of duplex DNA primarily at AT-rich sequences both as a monomer or as a side-by-side antiparallel dimer. The association phase of the distamycin binding reaction has not been studied in either of its binding modes, because of the lack of an adequate UV or CD signal at the low concentrations needed to monitor the fast bimolecular reaction. We report a significant increase in fluorescence amplitude, accompanied by a small red shift, on binding distamycin to its specific target sites. This signal can be used to monitor drug binding in steady-state and time-resolved processes. Distamycin shows extremely fast association with the 1:1 binding site, with a bimolecular rate of 7 x 10(7) M(-1) small middle dots(-1) and also fairly rapid dissociation ( approximately 3 s(-1)). When DNA is in excess, there is a slow component in the association reaction whose rate decreases strongly with increasing DNA concentration. Binding of the drug to the 2:1 site occurs in two distinct steps: fast, sequential binding of each drug molecule to the DNA with a bimolecular rate comparable to that at the 1:1 site, followed by a slow ( approximately 4 s(-1)) equilibration to the final population. Dissociation from the 2:1 site is approximately 40-fold slower than from the 1:1 site. This study provides the groundwork for analysis of the binding kinetics of longer polyamides and covalently linked polyamides that have recently been shown to inhibit transcription in vivo.

Increased susceptibility to development of triggered activity in myocytes from mice with targeted disruption of endothelial nitric oxide synthase

Nitric oxide generated by cardiac myocytes or delivered by drugs has been shown to regulate cardiac contractile function and has been implicated in suppressing some cardiac arrhythmias, although this remains controversial. We examined the ability of the soluble cardiac glycoside, ouabain, to trigger arrhythmic contractions in ventricular myocytes isolated from mice lacking a functional endothelial nitric oxide synthase gene (eNOS(null)). Arrhythmic activity, defined as aftercontractions, was induced with ouabain (50 micromol/L) and recorded using a video-motion detector in isolated, electrically driven single ventricular myocytes from adult eNOS(null)or from their wild-type (WT) littermates. The rate of ouabain-induced arrhythmic contractions was significantly higher in eNOS(null)myocytes than in WT myocytes. Application of the NO donor S-nitroso-acetylcysteine (SNAC) significantly diminished the frequency of arrhythmic contractions in eNOS(null)myocytes. The antiarrhythmic effect of NO, whether generated by eNOS in WT cells or by SNAC, could be partially reversed by 1H-[1,2,4]oxadiazolo-[4, 3-a]- quinoxalin-1-one (ODQ), a specific soluble guanylyl cyclase inhibitor. Ouabain significantly increased intracellular cGMP in WT but not eNOS(null)hearts, and this cGMP response was blocked by ODQ. Since cardiac glycoside- induced aftercontractions are activated by the transient inward current (I(ti)), the role of NO in ouabain (100 micromol/L)- induced I(ti)was examined using the nystatin-perforated patch-clamp technique. The frequency of ouabain-induced I(ti)was significantly higher in eNOS(null)myocytes than in WT myocytes, and this could be suppressed by SNAC. These data demonstrate that NO derived from myocyte eNOS activation suppresses ouabain-induced arrhythmic contractions by a mechanism that might involve activation of guanylyl cyclase and elevation of cGMP.

Maximum urine concentrating ability in children with Hb SC disease: effects of hydroxyurea

Studies in adults with Hb SC disease suggested that hydroxyurea reduced hemolysis and increased red cell hydration. Because increased hydration should diminish the polymerization tendency of Hb S we hypothesized that hydroxyurea might repair the urine concentration defect of HbSC disease. Eight Hb SC disease patients, aged 10 to 17 years, were given hydroxyurea daily. Maximal urine concentrating ability following overnight fasting and after subcutaneous arginine vasopressin (dDAVP), blood counts, and cell volumes were observed for 12-15 months. All patients had impaired urine concentrating ability prior to hydroxyurea treatment and failed to increase their ability to concentrate urine following treatment (maximum urine concentration after an overnight fast and dDAVP, 520-530 mOsm). Mean corpuscular volume (MCV) and reticulocyte MCV increased after administration of hydroxyurea, and the reticulocyte count and ratio of red cell hemoglobin to reticulocyte hemoglobin fell but there was little change in PCV. Hb F increased substantially in 2 patients but showed little change in the remaining patients. There was no evidence that hydroxyurea was associated with increased urine concentrating ability in children with Hb SC disease. These results may reflect irreversible renal medullary damage prior to beginning treatment or insufficient intensity or duration of treatment.

Oxidant mechanisms in toxic acute renal failure

Over the last decade, there is accumulating evidence for a role of reactive oxygen metabolites in the pathogenesis of a variety of renal diseases, including gentamicin, glycerol, cisplatin, and cyclosporine A models of toxic acute renal failure. Gentamicin has been shown both in in vitro and in vivo studies to enhance the generation of reactive oxygen metabolites. Iron is important in models of tissue injury, presumably because it is capable of catalyzing free-radical formation. Gentamicin has been shown to cause release of iron from renal cortical mitochondria. Scavengers of reactive oxygen metabolites as well as iron chelators provide protection in gentamicin-induced nephrotoxicity. In glycerol-induced acute renal failure, an animal model of rhabdomyolysis, there is enhanced generation of hydrogen peroxide, and scavengers of reactive oxygen metabolites and iron chelators provide protection. Although the dogma is that the myoglobin is the source of iron, recent studies suggest that cytochrome P450 may be an important source of iron in this model. In addition, there are marked alterations in antioxidant defenses, such as glutathione, as well as changes in heme oxygenase. Several recent in vitro and in vivo studies indicate an important role of reactive oxygen metabolites in cisplatin-induced nephrotoxicity. Thus, catalytic iron is increased both in vitro and in vivo by cisplatin, and iron chelators as well as hydroxyl radical scavengers have been shown to be protective. Recent studies indicate that cytochrome P450 may also be an important source of the catalytic iron in cisplatin nephrotoxicity. Cyclosporine A has been shown to enhance generation of hydrogen peroxide in vitro and enhance lipid peroxidation in vitro and in vivo. Antioxidants have been shown to be protective in cyclosporine A nephrotoxicity. This collective body of evidence suggests an important role for reactive oxygen metabolites in toxic acute renal failure and may provide therapeutic opportunities of preventing or treating acute renal failure in humans.

Role of cytochrome P-450 as a source of catalytic iron in cisplatin-induced nephrotoxicity

BACKGROUND

Iron plays a role in free radical-mediated tissue injury, including cisplatin-induced nephrotoxicity. However, the source of iron (catalyzing free radical reactions) is not known. We examined the role of cytochrome P-450 as a source of catalytic iron in cisplatin-induced nephrotoxicity both in vivo and in vitro.

METHODS

Cisplatin-induced acute renal failure was produced in rats by intraperitoneal injection of cisplatin (10 mg/kg body wt). Piperonyl butoxide, a cytochrome P-450 inhibitor, was administered intraperitoneally (400 mg/kg body wt twice at 48-hr intervals) prior to cisplatin injection. The effects of cisplatin in the absence or presence of piperonyl butoxide on the belomycin-detectable iron, cytochrome P-450 content in the kidney, and renal functional and histological changes were evaluated. In an in vitro study, the effect of cytochrome P-450 inhibitors, cimetidine or piperonyl butoxide, on cisplatin-induced cytotoxicity and catalytic iron release from LLC-PK1 cells was examined.

RESULTS

In cisplatin-treated rats, there was a marked decrease in the cytochrome P-450 content specifically in the kidney, accompanied by increased bleomycin-detectable iron content in the kidney. Piperonyl butoxide prevented cisplatin-induced loss of cytochrome P-450 as well as the increase of bleomycin-detectable iron in the kidney, along with both functional and histological protection. Both cimetidine and piperonyl butoxide prevented cisplatin-induced increase in bleomycin-detectable iron and cytotoxicity in LLC-PK1 cells. Treatment of cimetidine did not affect cellular uptake of cisplatin.

CONCLUSION

Cytochrome P-450, a group of heme proteins, may serve as a significant source of catalytic iron in cisplatin-induced nephrotoxicity.

Focal segmental glomerulosclerosis in children with acute lymphocytic leukemia: case reports and review of literature

PURPOSE

To report the occurrence of focal segmental glomerulosclerosis (FSGS) in children with acute lymphocytic leukemia (ALL), discuss pathogenesis and problems in management.

PATIENTS AND METHODS

Progressive renal dysfunction developed in two adolescent black girls with high-risk ALL who underwent renal biopsies that were consistent with FSGS. In both patients, no known etiologic factors, such as systemic lupus erythematosus, poststreptococcal glomerulonephritis, sickle cell anemia, or acquired immunodeficiency syndrome, were evident. FSGS induced by Adriamycin (Pharmacia & Upjohn, Columbus, OH) has been observed experimentally in rats. The patients had received anthracyclines and methotrexate, a known nephrotoxic chemotherapeutic agent.

RESULTS

One patient progressed to chronic renal failure and required prolonged dialysis followed by renal transplantation, though the leukemia remained in remission. The other patient is also in remission and on maintenance treatment for leukemia. She has persistent proteinuria and is currently undergoing a trial of high-dose steroid therapy.

CONCLUSION

The combination of FSGS with leukemia poses a management challenge to the clinician in terms of further treatment with potentially nephrotoxic drugs, complications of nephrotic syndrome (including infections), and timing of renal transplantation. Future studies should address whether FSGS represents a glomerular response to anthracycline-induced injury in susceptible black persons.

In vitro and in vivo evidence suggesting a role for iron in cisplatin-induced nephrotoxicity

Cisplatin is a widely used antineoplastic agent that has nephrotoxicity as a major side effect. The underlying mechanism of this nephrotoxicity is still not well known. Iron has been implicated to play an important role in several models of tissue injury, presumably through the generation of hydroxyl radicals via the Haber-Weiss reaction or other highly toxic free radicals. In the present study we examined the catalytic iron content and the effect of iron chelators in an in vitro model of cisplatin-induced cytotoxicity in LLC-PK1 cells (renal tubular epithelial cells) and in an in vivo model of cisplatin-induced acute renal failure in rats. Exposure of LLC-PK1 cells to cisplatin resulted in a significant increase in bleomycin-detectable iron (iron capable of catalyzing free radical reactions) released into the medium. Concurrent incubation of LLC-PK1 cells with iron chelators including deferoxamine and 1,10-phenanthroline significantly attenuated cisplatin-induced cytotoxicity as measured by lactate dehydrogenase (LDH) release. Bleomycin-detectable iron content was also markedly increased in the kidney of rats treated with cisplatin. Similarly, administration of deferoxamine in rats provided marked functional (as measured by blood urea nitrogen and creatinine) and histological protection against cisplatin-induced acute renal failure. In a separate study, we examined the role of hydroxyl radical in cisplatin-induced nephrotoxicity. Incubation of LLC-PK1 cells with cisplatin caused an increase in hydroxyl radical formation. Hydroxyl radical scavengers, dimethyl sulfoxide, mannitol and benzoic acid, significantly reduced cisplatin-induced cytotoxicity and, treatment with dimethyl sulfoxide or dimethylthiourea provided significant protection against cisplatin-induced acute renal failure. Taken together, our data strongly support a critical role for iron in mediating tissue injury via hydroxyl radical (or a similar oxidant) in this model of nephrotoxicity.

In vitro and in vivo evidence suggesting a role for iron in cisplatin-induced nephrotoxicity

Cisplatin is a widely used antineoplastic agent that has nephrotoxicity as a major side effect. The underlying mechanism of this nephrotoxicity is still not well known. Iron has been implicated to play an important role in several models of tissue injury, presumably through the generation of hydroxyl radicals via the Haber-Weiss reaction or other highly toxic free radicals. In the present study we examined the catalytic iron content and the effect of iron chelators in an in vitro model of cisplatin-induced cytotoxicity in LLC-PK1 cells (renal tubular epithelial cells) and in an in vivo model of cisplatin-induced acute renal failure in rats. Exposure of LLC-PK1 cells to cisplatin resulted in a significant increase in bleomycin-detectable iron (iron capable of catalyzing free radical reactions) released into the medium. Concurrent incubation of LLC-PK1 cells with iron chelators including deferoxamine and 1,10-phenanthroline significantly attenuated cisplatin-induced cytotoxicity as measured by lactate dehydrogenase (LDH) release. Bleomycin-detectable iron content was also markedly increased in the kidney of rats treated with cisplatin. Similarly, administration of deferoxamine in rats provided marked functional (as measured by blood urea nitrogen and creatinine) and histological protection against cisplatin-induced acute renal failure. In a separate study, we examined the role of hydroxyl radical in cisplatin-induced nephrotoxicity. Incubation of LLC-PK1 cells with cisplatin caused an increase in hydroxyl radical formation. Hydroxyl radical scavengers, dimethyl sulfoxide, mannitol and benzoic acid, significantly reduced cisplatin-induced cytotoxicity and, treatment with dimethyl sulfoxide or dimethylthiourea provided significant protection against cisplatin-induced acute renal failure. Taken together, our data strongly support a critical role for iron in mediating tissue injury via hydroxyl radical (or a similar oxidant) in this model of nephrotoxicity.

An 11-month-old with anti-glomerular basement membrane disease

Anti-glomerular basement membrane antibody disease is an autoimmune disease that has rarely been described in children, and no cases have previously been described in a patient younger than 2.5 years of age. We report an 11-month-old infant girl who developed anti-glomerular basement membrane disease and progressed to end-stage renal disease and eventual renal transplantation. Although it has been suggested that this disease does not occur in infants, the possibility of anti-glomerular basement membrane disease must be considered in the differential diagnosis of acute renal failure and glomerulonephritis in an infant. The characteristic linear pattern of immunofluorescent studies for Immunoglobulin (Ig) G is important in suggesting the diagnosis, which can be confirmed by serologic testing for antibody titers.

Oxidant mechanisms in toxic acute renal failure

Over the last decade, there has been accumulating evidence for a role of reactive oxygen metabolites in the pathogenesis of a variety of renal diseases, including gentamicin, glycerol, and cyclosporine A models of toxic acute renal failure. Gentamicin has been shown in both in vitro and in vivo studies to enhance the generation of reactive oxygen metabolites. Iron is important in models of tissue injury, presumably because it is capable of catalyzing free radical formation. Gentamicin has been shown to cause release of iron from renal cortical mitochondria. Scavengers of reactive oxygen metabolites as well as iron chelators provide protection in gentamicin-induced nephrotoxicity. In glycerol-induced acute renal failure, an animal model of rhabdomyolysis, there is enhanced generation of hydrogen peroxide, and scavengers of reactive oxygen metabolites and iron chelators provide protection. Although the dogma is that the myoglobin is the source of iron, the results of recent studies suggest that cytochrome P-450 may be an important source of iron in this model. In addition, there are marked alterations in antioxidant defenses, such as glutathione, as well as changes in heme oxygenase. Cyclosporine A has been shown to enhance the generation of hydrogen peroxide in vitro and lipid peroxidation in vitro and in vivo. Antioxidants have been shown to be protective in cyclosporine A nephrotoxicity. This collective body of evidence suggests an important role for reactive oxygen metabolites in toxic acute renal failure and may provide therapeutic opportunities of preventing or treating acute renal failure in humans.

Antibody against synthetic rat PTH peptide (1-34) blocks PTH-mediated cAMP formation and phosphate transport in opossum kidney cells

A novel antibody against synthetic rat parathyroid hormone (rPTH(1-34)) was successfully produced in rabbits at a titer of 1:3,000. The ability of this antibody to block PTH was studied utilizing the hormone-sensitive cAMP formation and Na(+)-dependent phosphate transport in the opossum kidney (OK) cells. rPTH peptide(1-34) stimulated cAMP formation and inhibited Na(+)-dependent phosphate transport in OK cells in a dose-dependent manner. Treatment of OK cells with the antisera significantly decreased the level of cAMP and attenuated the inhibition of Na(+)-dependent phosphate transport in response to rPTH(1-34) at a dilution of 1:1,000. Nonimmune rabbit sera at the same dilution did not influence these hormone-sensitive effects. We conclude that antibody against synthetic PTH peptide can be used to study the biological activities of this hormone.

Role of cytochrome P-450 in hydrogen peroxide-induced cytotoxicity to LLC-PK1 cells

The current study was designed to test the role of cytochrome P-450 in hydrogen peroxide-induced cytotoxicity, and to determine whether it may serve as a source of catalytic iron. Hydrogen peroxide led to iron release (as measured by iron/bathophenanthroline complex) from the microsomes prepared from LLC-PK1 cells. Cimetidine, which inhibits cytochrome P-450 by interacting with the heme iron, significantly blocked iron release, whereas ranitidine, which has a similar structure as cimetidine but is a weak inhibitor of P-450, did not have an effect (H2O2, 0.42 +/- 0.04; H2O2 + cimetidine, 0.23 +/- 0.02 nmol/mg protein; N = 4, P < 0.01). Exposure of LLC-PK1 cells to hydrogen peroxide (2.5 mM) resulted in a significant increase in the bleomycin-detectable iron (iron capable of catalyzing free radical reactions) content that was prevented by cimetidine, but not ranitidine. We then examined the effect of the inhibitors of cytochrome P-450 on cell death (as measured by Trypan blue exclusion) after exposure of LLC-PK1 cells to 2.5 mM hydrogen peroxide for 120 minutes. Inhibition of cytochrome P-450 by cimetidine significantly reduced the cell death; the effect was observed with 0.05 mM and was concentration dependent with 1 mM affording almost complete protection (H2O2, 59 +/- 1.3% vs. H2O2 + cimetidine, 11 +/- 0.7%; N = 5, P < 0.01). In contrast, ranitidine did not show any protection. We confirmed that the protective effect of cimetidine was not related to scavenging hydrogen peroxide or hydroxyl radicals or chelating iron. A second inhibitor of cytochrome P-450, piperonyl butoxide, had a similar dose-dependent beneficial effect against hydrogen peroxide-induced cell injury. Our data thus indicate an important role of cytochrome P-450 in hydrogen peroxide-induced cytotoxicity to LLC-PK1 cells and suggest that cytochrome P-450 may serve as a source of catalytic iron.

Kidney iron status in passive Heymann nephritis and the effect of an iron-deficient diet

In the study presented here, the iron status in the kidney in passive Heymann nephritis, a complement-dependent model of membranous nephropathy, was examined. To examine whether the effect of immune injury on iron status has a pathogenic role, the effect of an iron-deficient diet was also determined. Injection of the anti-Fx1A antibody (10 mg/100 g body wt) in Sprague-Dawley rats resulted in no change in the serum iron level, a marked increase in the urinary excretion rate of iron, a marked increase in non-heme iron content of kidney cortex, and a marked increase in the non-heme iron level in tubules. These increases in iron were prevented by feeding the rats an iron-deficient diet. In the rats fed a normal iron diet and injected with anti-Fx1A-lgG, there was no significant change in the non-heme iron level in glomeruli. However, an iron-deficient diet resulted in a significant decrease in the non-heme iron level in glomeruli, compared with its respective control. In addition, an iron-deficient diet significantly reduced urinary protein excretion rate (Day 5: iron-replete, 68 +/- 12 mg/24 h, N = 12; iron-deficient, 36 +/- 11, N = 10, P < 0.05) in the complement-dependent immune phase of the glomerular injury. Taken together, these data indicate a marked alteration in the iron status in the kidney and suggest an important role of iron in glomerular injury of passive Heymann nephritis.

Evidence for cytochrome P-450 as a source of catalytic iron in myoglobinuric acute renal failure

Iron has been implicated to play an important role in several models of tissue injury, including myoglobinuric acute renal failure. In this model, myoglobin released from the injured muscle is generally accepted as a source of iron. In the present study we measured the bleomycin-detectable iron (iron capable of catalyzing free radical reactions) in the kidneys and examined the role of cytochrome P-450 as a source of catalytic iron in glycerol-induced model of myoglobinuric acute renal failure. Rats were injected with 50% glycerol (8 ml/kg) i.m. after overnight water deprivation and sacrificed 24 hours later. There was a marked and a specific increase in the bleomycin-detectable iron content accompanied by a marked decrease in the cytochrome P-450 content in the kidneys of glycerol treated rats. We then examined the effects of two different cytochrome P-450 inhibitors, cimetidine (with ranitidine as a control) and piperonyl butoxide. Cimetidine, but not ranitidine, significantly prevented the increase of bleomycin-detectable iron in the kidneys of glycerol-treated rats. The loss of cytochrome P-450 content was substantially blocked by both inhibitors, cimetidine and piperonyl butoxide, but not by ranitidine. Both the inhibitors of cytochrome P-450 provided functional (as measured by BUN and creatinine) and histological protection against glycerol-induced acute renal failure. Our data thus demonstrate a marked increase in bleomycin-detectable iron in the kidneys of glycerol-treated rats. Our data also indicate that inhibitors of cytochrome P-450 provide protection against glycerol-induced acute renal failure and that cytochrome P-450 may be a significant source of this iron in this model of acute renal failure.

Role of 'catalytic' iron in an animal model of minimal change nephrotic syndrome

Treatment of minimal change disease, like most glomerulonephritides, is empirical because underlying mechanisms that cause glomerular injury are not known. We examined a pathogenic role of 'catalytic' iron in a model of minimal change nephrotic syndrome induced by injection of puromycin aminonucleoside (7.5 mg/100 g body wt) to rats. Although there was no significant change in non-heme iron content in glomeruli, the bleomycin-detectable iron (capable of catalyzing free radical reactions) was markedly increased in glomeruli from nephrotic rats when compared to control. In contrast, despite a marked and significant increase in the non-heme iron content in tubules, there was no significant change in the bleomycin-detectable iron in tubules from nephrotic rats. In a separate in vivo study, the iron chelator, deferoxamine, prevented the increase in the bleomycin-detectable iron in glomeruli and provided complete protection against proteinuria. Taken together, our data suggest an important pathogenetic role for glomerular catalytic iron in the puromycin aminonucleoside-induced minimal change nephrotic syndrome.

RecA.oligonucleotide filaments bind in the minor groove of double-stranded DNA

Escherichia coli RecA protein, in the presence of ATP or its analog adenosine 5'-[gamma-thio]triphosphate, polymerizes on single-stranded DNA to form nucleoprotein filaments that can then bind to homologous sequences on duplex DNA. The three-stranded joint molecule formed as a result of this binding event is a key intermediate in general recombination. We have used affinity cleavage to examine this three-stranded joint by incorporating a single thymidine-EDTA.Fe (T*) into the oligonucleotide part of the filament. Our analysis of the cleavage patterns from the joint molecule reveals that the nucleoprotein filament binds in the minor groove of an extended Watson-Crick duplex.

Glomerulocystic disease: unilateral involvement of a horseshoe kidney and in trisomy 18

Two occurrences of glomerulocystic kidney disease (GCD) in children younger than 1 year are described. One child was 3 months old with trisomy 18; the other child was 6 months old with GCD localized to one side of a horseshoe kidney. Lectin and immunohistochemical studies in tissue from the second child suggested that the entire nephron may be affected in GCD. There may also be overlap of morphological features between GCD and early stages of autosomal dominant polycystic kidneys.

Increase in bleomycin-detectable iron in ischaemia/reperfusion injury to rat kidneys

Iron has been shown to be important in ischaemic, immune and toxic forms of tissue injury in various organs. Although it is generally accepted that iron participates in the generation of powerful oxidant species (e.g. hydroxyl radicals) there has not been any direct evidence that iron capable of catalysing free-radical reactions is increased in tissues in these models of injury. In the present study we demonstrate that ischaemia/reperfusion injury to the kidney results in no significant change in total, nonhaem or ferritin iron levels, but there is a marked and specific increase in bleomycin-detectable iron (capable of catalysing free-radical reactions) in the kidney. The increase in bleomycin-detectable iron is observed only after reperfusion but not during the ischaemic period. In a separate study we demonstrate that despite a drastic reduction in the iron content in the kidney, as a result of feeding an iron-deficient diet, there is a similar and a marked increase in the bleomycin-detectable iron in kidneys accompanied by a lack of protection against ischaemia/reperfusion injury.

Effect of selenium-deficient diet in experimental glomerular disease

We examined the effect of a selenium-deficient diet on two experimental models of glomerular disease, the puromycin aminonucleoside (PAN)-induced nephrotic syndrome, a model of minimal change disease, and passive Heymann nephritis, a complement-dependent and neutrophil-independent model that resembles membranous nephropathy. The specific activity of selenium-dependent glutathione peroxidase was markedly reduced in the liver, the kidney cortex, and in glomeruli in weanling male Sprague-Dawley rats placed on a selenium-deficient diet for 6 wk compared with rats fed a selenium-replete diet, with no significant differences in the specific activities of superoxide dismutase or catalase. PAN-injected selenium-deficient rats had a marked and significantly greater proteinuria throughout the course of the experiment compared with PAN-injected selenium-replete rats with no significant histological differences. In the passive Heymann nephritis model induced by injecting anti-Fx1A immunoglobulin G, rats fed a selenium-deficient diet had significantly higher urinary protein (day 5: 91 +/- 16 mg/24 h, n = 10) compared with rats fed a selenium-replete diet (52 +/- 5 mg/24 h, n = 11) with no differences in the amount of antibody deposited in the kidney. The most likely explanation for the effect of a selenium-deficient diet is that selenium deficiency resulted in a marked reduction of glutathione peroxidase, thus indicating an important role of glutathione peroxidase in these models of glomerular injury.

Effects of reduced renal function and dietary protein on muscle protein synthesis

We describe a rat model of renal failure that separates catabolic and anabolic states from each other. Muscle protein synthesis was compared during the anabolic period between sham (S) operated and renal failure (RF) rats that were fed different levels of dietary protein. Male rats weighing between 60 and 80 g first had a partial left nephrectomy and then were given a tryptophan deficient diet from four to six days to induce weight loss. On the second day of the diet either a renal decapsulation (S rats) or a simple right nephrectomy (RF rats) was done to enhance the catabolic response in both and to induce renal failure in the RF rats. Following the period of feeding the deficient diet, both groups were fed a nutritionally complete 14, 17, 20 or 30% protein diet for three to five days. This induced a brisk anabolic response as measured by weight gain. Differences in body weight between the S and RF rats after three to five days on the repletion diet generally was less than 10%. The rats then were fasted overnight, fed a standard meal and muscle protein synthesis (Sm%) was measured two hours post-feeding. Sm% was estimated from the incorporation of 3H phenylalanine (PHE) into muscle 10 minutes following the i.v. injection of 3HPHE (25 muCi/100 g body wt) with carrier PHE to flood all the precursor amino acid pools. Weight loss in the catabolic phase was greater and the net weight gain for the two phases was less in the RF group. Overall, renal failure resulted in a significant reduction in Sm% (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dietary protein intake on muscle protein synthesis and degradation in rats with gentamicin-induced acute renal failure

In the study presented here, the muscle protein synthesis and degradation in gentamicin-induced acute renal failure were examined in rats fed a low (7%)-, normal (22%)-, and high (35%)-isocaloric protein diet. Male Sprague-Dawley rats were fed equivalent amounts of these diets for 10 days and then received daily subcutaneous injections of either 1 mL of sterile isotonic saline or 100 mg/kg of gentamicin for 7 consecutive days. The rats were sacrificed the following day, and epitrochlearis muscles were obtained for measurement of protein turnover. The serum creatinine in each of the gentamicin-treated groups were significantly higher than that in the saline-treated controls but were no different from each other. Muscle protein synthesis (calculated from the incorporation of radiolabeled (U-14C) phenylalanine) was slightly but not significantly decreased in gentamicin-treated rats as compared with that of the corresponding saline controls in each of the dietary groups. Net protein degradation (the rate of tyrosine release into media) in the 7 and 22% gentamicin-treated groups was similar to that in the corresponding saline controls. In contrast, net protein degradation was significantly greater in the 35% gentamicin group of rats when compared with that in the 7 and 22% gentamicin groups and its own control. In the 7 and 22% saline- and gentamicin-treated protein groups, there was a reduction in net protein degradation in response to insulin. In contrast, the net protein degradation continued to remain significantly elevated in the 35% gentamicin-treated group, despite addition of insulin, when compared with that in the 7 and 22% gentamicin groups and its own control.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathogenesis and treatment of edema

Edema results from excess accumulation of interstitial fluid. This may be due to increased transfer of fluid across the capillary membranes or excess retention of salt and water. The kidneys play a significant role in promoting salt and water homeostasis. Correction of the primary disorder should be the main goal in the management. Diuretics aid in promoting increased excretion of salt and water.

Acute renal failure in Reye's syndrome

Three patients with initial clinical manifestations and biochemical findings suggestive of a diagnosis of Reye's syndrome had acute renal insufficiency develop and had evidence of consumptive coagulopathy, not generally considered features of the syndrome. As a group, they could not be distinguished, either on the basis of their clinical manifestations or liver pathologic findings, from the 17 patients with Reye's syndrome without renal failure seen in our institution during the same period of time. The use of osmotic diuretics in an effort to decrease cerebral edema may be life threatening in these patients with compromised renal function since hypervolemia, cardiac failure, and worsening of cerebral edema may occur.