Expression of natriuretic peptide in ventricular myocardium of failing human hearts and its correlation with the severity of clinical and hemodynamic impairment

Right ventricular dysfunction is superior and sufficient for risk stratification by a pulmonary embolism response team

Several risk stratification tools are available to predict short-term mortality in patients with acute pulmonary embolism (PE). The presence of right ventricular (RV) dysfunction is an independent predictor of mortality and may be a more efficient way to stratify risk for patients assessed by a Pulmonary Embolism Response Team (PERT). We evaluated 571 patients presenting with acute PE, then stratified them by the pulmonary embolism severity index (PESI), by the BOVA score, or categorically as low risk (no RV dysfunction by imaging), intermediate risk/submassive (RV dysfunction by imaging), or high risk/massive PE (RV dysfunction with sustained hypotension). Using imaging data to firstly define the presence of RV strain, and plasma cardiac biomarkers as additional evidence for myocardial dysfunction, we evaluated whether PESI, BOVA, or RV strain by imaging were more appropriate for determining patient risk by a PERT where rapid decision making is important. Cardiac biomarkers poorly distinguished between PESI classes and BOVA stages in patients with acute PE. Cardiac TnT and NT-proBNP easily distinguished low risk from submassive PE with an area under the curve (AUC) of 0.84 (95% CI 0.73-0.95, p < 0.0001), and 0.88 (95% CI 0.79-0.97, p < 0.0001), respectively. Cardiac TnT and NT-proBNP easily distinguished low risk from massive PE with an area under the curve (AUC) of 0.89 (95% CI 0.78-1.00, p < 0.0001), and 0.89 (95% CI 0.82-0.95, p < 0.0001), respectively. In patients with RV dysfunction, the predicted short-term mortality by PESI score or BOVA stage was lower than the observed mortality by a two-fold order of magnitude. The presence of RV dysfunction alone in the context of acute PE is sufficient for the purposes of risk stratification. More complicated risk stratification tools which require the consideration of multiple clinical variables may under-estimate short-term mortality risk.

Regional mapping of myocardial hibernation phenotype in idiopathic end-stage dilated cardiomyopathy

Myocardial hibernation (MH) is a well-known feature of human ischaemic cardiomyopathy (ICM), whereas its presence in human idiopathic dilated cardiomyopathy (DCM) is still controversial. We investigated the histological and molecular features of MH in left ventricle (LV) regions of failing DCM or ICM hearts. We examined failing hearts from DCM (n = 11; 41.9 ± 5.45 years; left ventricle-ejection fraction (LV-EF), 18 ± 3.16%) and ICM patients (n = 12; 58.08 ± 1.7 years; LVEF, 21.5 ± 6.08%) undergoing cardiac transplantation, and normal donor hearts (N, n = 8). LV inter-ventricular septum (IVS) and antero-lateral free wall (FW) were transmurally (i.e. sub-epicardial, mesocardial and sub-endocardial layers) analysed. LV glycogen content was shown to be increased in both DCM and ICM as compared with N hearts (P < 0.001), with a U-shaped transmural distribution (lower values in mesocardium). Capillary density was homogenously reduced in both DCM and ICM as compared with N (P < 0.05 versus N), with a lower decrease independent of the extent of fibrosis in sub-endocardial and sub-epicardial layers of DCM as compared with ICM. HIF1-α and nestin, recognized ischaemic molecular hallmarks, were similarly expressed in DCM-LV and ICM-LV myocardium. The proteomic profile was overlapping by ˜50% in DCM and ICM groups. Morphological and molecular features of MH were detected in end-stage ICM as well as in end-stage DCM LV, despite epicardial coronary artery patency and lower fibrosis in DCM hearts. Unravelling the presence of MH in the absence of coronary stenosis may be helpful to design a novel approach in the clinical management of DCM.

Autosomal recessive atrial dilated cardiomyopathy with standstill evolution associated with mutation of Natriuretic Peptide Precursor A

BACKGROUND

Atrial dilatation and atrial standstill are etiologically heterogeneous phenotypes with poorly defined nosology. In 1983, we described 8-years follow-up of atrial dilatation with standstill evolution in 8 patients from 3 families. We later identified 5 additional patients with identical phenotypes: 1 member of the largest original family and 4 unrelated to the 3 original families. All families are from the same geographic area in Northeast Italy.

METHODS AND RESULTS

We followed up the 13 patients for up to 37 years, extended the clinical investigation and monitoring to living relatives, and investigated the genetic basis of the disease. The disease was characterized by: (1) clinical onset in adulthood; (2) biatrial dilatation up to giant size; (3) early supraventricular arrhythmias with progressive loss of atrial electric activity to atrial standstill; (4) thromboembolic complications; and (5) stable, normal left ventricular function and New York Heart Association functional class during the long-term course of the disease. By linkage analysis, we mapped a locus at 1p36.22 containing the Natriuretic Peptide Precursor A gene. By sequencing Natriuretic Peptide Precursor A, we identified a homozygous missense mutation (p.Arg150Gln) in all living affected individuals of the 6 families. All patients showed low serum levels of atrial natriuretic peptide. Heterozygous mutation carriers were healthy and demonstrated normal levels of atrial natriuretic peptide.

CONCLUSIONS

Autosomal recessive atrial dilated cardiomyopathy is a rare disease associated with homozygous mutation of the Natriuretic Peptide Precursor A gene and characterized by extreme atrial dilatation with standstill evolution, thromboembolic risk, preserved left ventricular function, and severely decreased levels of atrial natriuretic peptide.

Prior exercise training improves the outcome of acute myocardial infarction in the rat

OBJECTIVES

The aim of this research was to investigate the structural, functional, and molecular features of the remodeling heart in prior swim-trained infarcted rats.

BACKGROUND

Physical exercise training is a known protective factor against cardiovascular morbidity and mortality. The structural and molecular aspects underlying this protection in the remodeling heart have not been investigated.

METHODS

After seven weeks of swimming exercise training, rats underwent surgical ligation of the left coronary artery followed by a four-week sedentary period. Untrained control rats underwent the same surgical protocol. Left ventricular function was assessed by echocardiography four weeks after infarction, and hearts were sampled for histological and molecular analysis. Ribonucleic acid from the surviving left ventricle was analyzed by complementary deoxyribonucleic acid arrays followed by Northern blotting or quantitative reverse transcription polymerase chain reaction of selected messenger ribonucleic acids (mRNAs).

RESULTS

Scar area was 1.6-fold smaller (p = 0.0002), arteriolar density was 1.7-fold higher (p = 0.0002), and left ventricular shortening fraction was 1.9-fold higher (p = 0.003) in the exercise-trained compared with sedentary hearts. Eleven genes whose expression level varied by at least +/-1.5-fold distinguished the prior exercised rats from their sedentary counterparts. Compared with sedentary, the exercised hearts displayed 9- and 2.4-times lower levels of atrial natriuretic peptide and aldolase mRNA (p = 0.03 and 0.04, respectively), and a 2.7- and 1.9-fold higher abundance of cytochrome c-oxidase and fatty acid binding protein, respectively (p < 0.03, each).

CONCLUSIONS

Swimming exercise training before acute myocardial infarction reduces scar size, increases arteriole density, and manifests adaptation of stress- and energy-metabolism-related genes that may contribute to the improved heart function observed during remodeling.

Genetic predisposition to heart failure

This review describes the numerous and complex molecular systems that are either known players or candidates in heart failure(HF). All systems whose genetic background has been investigated to date in HF are listed and discussed. Discussion also includes functional notes and known genetic polymorphisms already investigated in HF or candidates that have not yet been investigated. Despite substantial research on HF, relatively few coordinated studies have been conducted that assign precise risk to specific genetic polymorphisms. Identification of risk associated with genetic variations and subsequent translation of genetic knowledge into clinical practice will likely progress only in cases of large coordinated studies based on identical standards. The potential result will be a more accurate definition of HF identified as an evolving complex of cardiovascular diseases.

Ventricular expression of atrial natriuretic peptide in chronic chagasic cardiomyopathy is not induced by myocarditis

BACKGROUND

The ventricles of the normal heart are virtually devoid of atrial natriuretic peptide (ANP). Although ANP occurs in ventricles submitted to elevated wall stress, it is not clear whether ANP expression is affected by myocarditis. We investigated the immunohistochemical expression of ANP in chronic chagasic cardiomyopathy, an inflammatory cardiomyopathy caused by infection with the protozoan Trypanosoma cruzi.

METHODS

Necropsy samples from the left and right ventricles of 16 patients exhibiting chronic chagasic cardiomyopathy were evaluated for myocarditis, fibrosis, T. cruzi parasites and ANP immunoreactivity. The diameters of 50 myocytes per sample were measured.

RESULTS

ANP was present in myocytes of the subendocardial region in 13/16 (81.3%) left and 10/16 (62.5%) right ventricular samples (P=0.25). Myocytes present in the inflammatory foci, near the infiltrating inflammatory cells but distant from the subendocardial region, did not express ANP. Trypanosoma cruzi parasites exhibited intense immunoreactivity for ANP. The mean myocyte diameter and the incidence of myocarditis, fibrosis, and T. cruzi parasites was similar between the left and right ventricular samples. No statistical differences were found between the ANP-positive and ANP-negative cases.

CONCLUSIONS

In chronic chagasic cardiomyopathy, both ventricles exhibit hypertrophy, fibrosis and ANP in the subendocardial region. The inflammatory infiltrate does not induce ANP expression in the myocytes. Regional stress but not myocarditis itself, is probably responsible for ventricular ANP expression in myocarditis.

Canine idiopathic dilated cardiomyopathy. Part II: pathophysiology and therapy

Dilated cardiomyopathy (DCM) in dogs is characterized by ventricular and atrial enlargement, and systolic and diastolic dysfunction, with congestive heart failure (CHF) often developing at some stage. With greater understanding of the impact of neuroendocrine stimulation in heart disease, the understanding of the pathophysiology for CHF has changed considerably. It is no longer considered only to be a simple haemodynamic consequence of pump dysfunction, but is now characterized as a complex clinical syndrome with release of many neurohormones, which are believed to have impact on the progression of disease. This change in our understanding of the pathophysiology of CHF has important therapeutic implications. There are strong indications, although not yet proven, that drugs designed to influence the neuroendocrine activity, such as Angiotensin Converting Enzyme (ACE) inhibitors and beta-receptors antagonists, are efficacious as adjunct therapy of heart failure attributable to DCM in dogs. The benefits of drugs designed to influence the myocardial contractile state (positive inotropes) have not been fully evaluated. However, evidence has emerged in recent years indicating that new types of positive inotropes may be beneficial in dogs with DCM. This review focuses on the neuroendocrine aspects of DCM and their possible therapeutic implications and the place for long-term inotropic support in dogs with DCM.

Effects of dilated cardiomyopathy on the renin-angiotensin-aldosterone system, atrial natriuretic peptide activity, and thyroid hormone concentrations in dogs

OBJECTIVE

To evaluate the effect of dilated cardiomyopathy (DCM) on activity of the renin-angiotensin-aldosterone system (RAAS), the N-terminal fragment of proatrial natriuretic peptide (NT-proANP), and thyroid hormone concentrations in dogs.

ANIMALS

15 dogs with clinical signs of DCM, 15 dogs without clinical signs of DCM, and 15 age-, breed-, and sex-matched control dogs.

PROCEDURE

Physical examinations, thoracic radiography, ECG, and echocardiography were performed on all dogs, and blood and urine samples were collected.

RESULTS

Plasma renin activity (PRA), plasma aldosterone concentration (PAC), urine aldosterone-to-creatinine ratio, and NT-proANP concentrations were significantly increased in dogs with clinical signs of DCM, compared with dogs without clinical signs and control dogs. Thyroid-stimulating hormone and total thyroxine concentrations did not differ significantly among groups; however, free thyroxine (FT4) concentrations were significantly decreased in dogs with clinical signs of DCM, compared with control dogs and DCM-dogs without clinical signs. Concentrations of PRA, PAC, FT4, and urine aldosterone-to-creatinine ratio were significantly correlated, whereas plasma concentrations of NT-proANP only correlated with FT4 concentration.

CONCLUSION AND CLINICAL RELEVANCE

In dogs with clinical signs of DCM, increased concentrations of components of the RAAS were associated with increased concentrations of NT-proANP Analysis of the neurohormonal system may aid in identification of clinical stages of DCM for groups of dogs, but the range is too great and there are too many dogs that have neurohormonal concentrations within reference ranges to assess dogs on an individual basis.

Stem Cell Factor Is Localized in, Released from, and Cleaved by Human Mast Cells

Stem cell factor (SCF) is the most important cytokine regulating human mast cell growth and functions. The immunogold technique showed SCF in the secretory granules of skin mast cells and in lung parenchymal mast cells (HLMC). Immunoreactive SCF (iSCF) was detected in cell lysates of HLMC, but not in basophils; iSCF and histamine were detected in supernatants of HLMC 3 min after challenge with anti-FcεRI or anti-IgE, and iSCF in supernatants rapidly declined after 30 min, whereas histamine remained unchanged for 120 min. HPLC and electrospray mass spectrometry (ES/MS) analysis of recombinant human SCF1–166 (18,656.9 ± 0.9 Da) treated with chymase showed a polypeptide of 17,977.1 ± 0.6 Da and a minor component of 697.4 ± 0.1 Da generated by specific cleavage at Phe159. SCF1–166 and SCF1–159 similarly activated HLMC, potentiated anti-IgE-induced activation of these cells, and stimulated HLMC chemotaxis. SCF159–166 had no effect on mast cells. Western blot analysis of supernatants of anti-IgE-activated HLMC incubated with recombinant human SCF1–166 showed that SCF1–166 was rapidly cleaved to SCF1–159 and SCF1–144. Experiments with supernatants of anti-IgE-activated HLMC incubated with SCF1–166 yielded similar results. In conclusion, SCF is stored in mast cell secretory granules and is immunologically released by human mast cells. SCF1–166 is rapidly and specifically cleaved to SCF1–159 by chymase, which retains its biological effect on mast cells. SCF is also cleaved by other proteases to several SCF species whose possible biological activities remain to be established.

Expression of endothelin-1, endothelin-converting enzyme, and endothelin receptors in chronic heart failure

BACKGROUND

Elevated plasma levels of endothelin (ET)-1 have been reported in association with heart diseases, including heart failure. Furthermore, it has been suggested that ET-1 acts as a local autocrine/paracrine factor with biological activities such as vasoconstriction, mitogenesis, and inotropic effects on the heart. This study investigated alterations of ET-1, ET receptor, and endothelin-converting enzyme (ECE) expression in left ventricular myocardium from patients with end-stage heart failure.

METHODS AND RESULTS

mRNA concentrations of ETA and ETB receptors, prepro-ET-1 (ppET-1), and ECE in left ventricles from nonfailing donors hearts (NF) and from patients with end-stage chronic heart failure (NYHA functional class IV) due to dilated cardiomyopathy (DCM) were compared by use of a competitive reverse transcription-polymerase chain reaction technique. There was no significant difference in mRNA expression for ppET-1, ECE-1, and ETA receptors, whereas a significant reduction of ETB-receptor mRNA was observed in DCM hearts. 125I-labeled ET-1 radioligand binding studies demonstrated a significant downregulation of ETB receptors, whereas ETA-receptor density was increased in membranes from DCM hearts. Phosphoramidon-sensitive ECE activity and immunodetectable amounts of ECE protein in left ventricular membrane preparations did not differ between NF and DCM hearts. Finally, immunoreactive ET-1 concentrations were increased in DCM hearts.

CONCLUSIONS

The present study demonstrates changes in the ET-receptor expression pattern in favor of the ETA receptor in human end-stage heart failure. Furthermore, activation of the cardiac ET system with increased tissue ET-1 concentrations in the failing myocardium is observed. This is more likely due to decreased clearance than to increased synthesis, because ppET-1 gene expression and ECE activity are unchanged.

Coexistence of mitochondrial DNA and beta myosin heavy chain mutations in hypertrophic cardiomyopathy with late congestive heart failure

OBJECTIVE

To investigate the possible coexistence of mitochondrial DNA (mtDNA) mutations in patients with beta myosin heavy chain (beta MHC) linked hypertrophic cardiomyopathy (HCM) who develop congestive heart failure.

DESIGN

Molecular analysis of beta MHC and mtDNA gene defects in patients with HCM.

SETTING

Cardiovascular molecular diagnostic and heart transplantation reference centre in north Italy.

PATIENTS

Four patients with HCM who underwent heart transplantation for end stage heart failure, and after pedigree analysis of 60 relatives, eight additional affected patients and 27 unaffected relatives. A total of 111 unrelated healthy adult volunteers served as controls. Disease controls included an additional 27 patients with HCM and 102 with dilated cardiomyopathy.

INTERVENTION

Molecular analysis of DNA from myocardial and skeletal muscle tissue and from peripheral blood specimens.

MAIN OUTCOME MEASURES

Screening for mutations in beta MHC (exons 3-23) and mtDNA tRNA (n = 22) genes with denaturing gradient gel electrophoresis or single strand conformational polymorphism followed by automated DNA sequencing.

RESULTS

One proband (kindred A) (plus seven affected relatives) had arginine 249 glutamine (Arg249Gln) beta MHC and heteroplasmic mtDNA tRNAIle A4300G mutations. Another unrelated patient (kindred B) with sporadic HCM had identical mutations. The remaining two patients (kindred C), a mother and son, had a novel beta MHC mutation (lysine 450 glutamic acid) (Lys450Glu) and a heteroplasmic missense (T9957C, phenylalanine (Phe)-->leucine (Leu)) mtDNA mutation in subunit III of the cytochrome C oxidase gene. The amount of mutant mtDNA was higher in the myocardium than in skeletal muscle or peripheral blood and in affected patients than in asymptomatic relatives. Mutations were absent in the controls. Pathological and biochemical characteristics of patients with mutations Arg249Gln plus A4300G (kindreds A and B) were identical, but different from those of the two patients with Lys450Glu plus T9957C(Phe-->Leu) mutations (kindred C). Cytochrome C oxidase activity and histoenzymatic staining were severely decreased in the two patients in kindreds A and B, but were unaffected in the two in kindred C.

CONCLUSIONS

beta MHC gene and mtDNA mutations may coexist in patients with HCM and end stage congestive heart failure. Although beta MHC gene mutations seem to be the true determinants of HCM, both mtDNA mutations in these patients have known prerequisites for pathogenicity. Coexistence of other genetic abnormalities in beta MHC linked HCM, such as mtDNA mutations, may contribute to variable phenotypic expression and explain the heterogeneous behaviour of HCM.

Stem cell factor in mast cells and increased mast cell density in idiopathic and ischemic cardiomyopathy

BACKGROUND

We compared cardiac mast cell (HHMC) density and the immunological and nonimmunological release of mediators from mast cells isolated from heart tissue of patients with idiopathic dilated (DCM) (n=24) and ischemic cardiomyopathy (ICM) (n = 10) undergoing heart transplantation and from control subjects (n = 10) without cardiovascular disease.

METHODS AND RESULTS

HHMC density in DCM (18.4+/-1.6 cells/mm2) and ICM (18.4+/-1.5 cells/mm2) was higher than that in control hearts (5.3+/-0.7 cells/mm2; P<.01). The histamine and tryptase contents of DCM and ICM hearts were higher than those of control hearts. The histamine content of the hearts was correlated with mast cell density (r(s)=.91; P<.001). Protein A/gold staining of heart tissue revealed stem cell factor (SCF), the principal growth, differentiating, and activating factor of human mast cells, in HHMC secretory granules. Histamine release from cardiac mast cells caused by immunological (anti-IgE and rhSCF) and nonimmunological stimuli (Ca2+ ionophore A23187) was higher in patients with DCM and ICM compared with control subjects. Immunological activation of HHMC induced a significantly greater release of tryptase and LTC4 in patients with DCM and ICM compared with control subjects.

CONCLUSIONS

Histamine and tryptase content and mast cell density are higher in failing hearts than in control hearts. SCF, present in secretory granules of HHMC, might represent an autocrine factor sustaining mast cell hyperplasia in heart tissue in these patients. The increased local release of fibrogenic factors (eg, histamine, tryptase, and leukotriene C4) might contribute to collagen accumulation in the hearts of patients with cardiomyopathy.

Preserved Frank-Starling mechanism in human end stage heart failure

OBJECTIVE

The goal of the present study was to examine the ability of failing myocardium to respond to enhanced preload with an increase in force development.

METHODS

The effect of various preload conditions (2.5-15 mN) on force development was studied in right ventricular trabeculae carneae from explanted human failing hearts with ischemic cardiomyopathy (ICM, n = 5, 42 preparations) or idiopathic dilated cardiomyopathy (DCM, n = 9, 77 preparations). To determine the severity of cardiac impairment we measured the positive inotropic effect of beta-adrenoceptor stimulation and calcium (ISO/Ca2+ ratio) and the expression of atrial natriuretic peptide (ANP) mRNA in all hearts.

RESULTS

(1) Force of contraction increased with stepwise augmentation of preload (length at 2.5 mN preload to length of maximal force development) from 3.7 +/- 0.5 (ICM) and 2.7 +/- 0.4 (DCM) to 8.3 +/- 0.9 and 6.5 +/- 0.8 mN/mm2, respectively (p < 0.05). (2) The ISO/Ca2+ ratio was 0.40 +/- 0.04 (ICM) and 0.35 +/- 0.03 (DCM), respectively. (3) ANP mRNA was expressed in all preparations, albeit at greatly varying levels (ICM 22.5 +/- 6.1 and DCM 18.7 +/- 4.7 normalized arbitrary units). (4) Contraction experiments performed in left ventricular tissue (n = 3, 32 preparations) essentially confirmed the results.

CONCLUSION

The Frank-Starling mechanism is preserved in terminally failing human hearts irrespective of the underlying etiology. We found no relation between the severity of cardiac impairment as assessed by either ANP expression or the ISO/Ca2+ ratio and the ability of failing human myocardium to respond to enhanced preload with an increase in force development.

Significance of raised natriuretic peptides after bicaval and standard cardiac transplantation

BACKGROUND

High levels of plasma atrial natriuretic peptide (ANP) and ventricular natriuretic peptide (BNP) have been identified after standard orthotopic cardiac transplantation. It has been postulated that the high ANP levels are a result of persistent secretion from the large residual atrial mass after transplantation. This study was undertaken to investigate the significance of raised ANP and BNP levels after standard and bicaval orthotopic heart transplantation.

METHODS

Plasma ANP and BNP levels were measured in 40 ambulatory, randomly selected cardiac transplant patients (group A, n = 20 had bicaval transplantation; group B, n = 20 had standard transplantation) and 10 healthy volunteers (group C). Cardiac transplant patients underwent endomyocardial biopsy and hemodynamic evaluation.

RESULTS

Plasma levels of ANP and BNP were elevated in the transplant recipients in comparison with normal volunteers (p = 0.0001 and p < 0.0001, respectively). There was no significant difference in the ANP levels between group A and group B, whereas BNP levels were higher in group B compared with group A (p = 0.03). Linear regression analysis showed that a faster heart rate, high mean pulmonary artery pressure, high pulmonary capillary wedge pressure, and high transpulmonary gradient were associated with higher levels of BNP (p < 0.05). Lower mean systemic pressure was associated with higher levels of ANP (p < 0.05).

CONCLUSIONS

High levels of ANP and BNP are synthesized and secreted by the transplanted denervated human heart regardless of the surgical technique. The level of BNP correlates with ventricular performance and afterload. The bicaval technique seems to be associated with better left ventricular and right ventricular diastolic performance.

Human synovial mast cells. I. Ultrastructural in situ and in vitro immunologic characterization

OBJECTIVE

To examine the ultrastructure of human synovial mast cells in situ, to identify immunologic and nonimmunologic stimuli that activate these cells in vitro, and to quantify a number of preformed and de novo-synthesized mediators.

METHODS

We conducted an ultrastructural study of synovial mast cells in situ and performed immunoelectron microscopy localization of tryptase and chymase. Isolated synovial mast cells were analyzed biochemically, immunologically, and functionally in vitro and compared with cells from human lung, heart, and skin.

RESULTS

Ultrastructural study of synovial tissue revealed mast cells with homogeneously dense, scrolled, crystal, and mixed granules, and lipid bodies in the cytoplasm. A small percentage of mast cells showed evidence of degranulation. Immunoelectron microscopy demonstrated the subcellular localization of tryptase and chymase over granules of > 90% of the mast cells, which were of the MCTC subtype. Isolated synovial mast cells released histamine in response to immunologic (anti-IgE and anti-Fc epsilon receptor I [anti-Fc epsilon RI]) and nonimmunologic (substance P, recombinant human stem cell factor, and 48/80) stimuli, but did not respond to recombinant human C5a in vitro. Synovial mast cells differed from those isolated from other human tissues, in a variety of immunologic and biochemical features. There was a linear correlation between the percentage of histamine secretion and tryptase release (r = 0.79, P < 0.001) induced by cross-linking of Fc epsilon RI. Cross-linking of IgE with anti-IgE on synovial mast cells induced de novo synthesis of prostaglandin D2 (mean +/- SEM 87.5 +/- 4.9 ng/10(6) cells) and of leukotriene C4 (57.6 +/- 17.8 ng/10(6) cells).

CONCLUSION

Mast cells ultrastructurally characterized in situ in synovial tissue were seen to differ from mast cells previously isolated from other human tissues. This raises the possibility that the local microenviroment influences their phenotype. Isolation of mast cells from human synovia can be useful for studying their role and their mediators in patients with arthritis.

Differential localization of atrial natriuretic peptide and skeletal alpha-actin messenger RNAs in left ventricular myocytes of patients with dilated cardiomyopathy

OBJECTIVES

This study was designed to determine whether atrial natriuretic peptide and skeletal alpha-actin messenger RNAs (mRNAs) are co-localized in ventricular myocytes of patients with dilated cardiomyopathy.

BACKGROUND

Atrial natriuretic peptide and skeletal alpha-actin are known as augmented genes with cardiac hypertrophy. However, the expression and localization of both genes in chronic failing heart remain unclear.

METHODS

Left ventricular biopsy specimens were obtained from 14 patients with dilated cardiomyopathy. Atrial natriuretic peptide and skeletal alpha-actin mRNAs were detected by in situ hybridization with specific sulfur-35 uridine triphosphate-labeled RNA probes in the serial sections.

RESULTS

Atrial natriuretic peptide mRNA was detected in 10 patients, and intense signals were localized in the myocytes located in the subendocardium and around the interstitial fibrous area. By contrast, skeletal alpha-actin mRNA was homogeneously detected in all myocytes in seven patients. By left ventriculography, patients with skeletal alpha-actin-positive findings had a lower ejection fraction (37.1 +/- 6.0%) than those with negative findings (46.3 +/- 5.8%, p < 0.05), but atrial natriuretic peptide mRNA expression was not related to left ventricular function.

CONCLUSIONS

These results indicate that the expression of atrial natriuretic peptide and skeletal alpha-actin mRNAs are not always co-localized in the left ventricle of patients with dilated cardiomyopathy and suggest that the mechanisms of the regulation of these two genes in the chronic failing heart are different.

Electrolyte disturbances in chronic heart failure: metabolic and clinical aspects

The pathophysiology of congestive heart failure (CHF) includes conditions (e.g., activation of the renin-angiotensin-aldosterone system) which, when combined with CHF therapies, make patients afflicted with this syndrome quite susceptible to electrolyte disturbances. The most commonly encountered are hyponatremia, hypokalemia, and hypomagnesemia. These derangements are of vast clinical importance; their development not only represents an immediate threat to the CHF patient (e.g., dysrhythmias secondary to hypokalemia), but are also indicative of underlying pathophysiologic events, an unfavorable clinical course, and occasionally an adverse therapeutic response. The optimal care of CHF patient includes the recognition and management of these electrolyte disturbances.

Increased plasma atrial natriuretic peptide levels after heart transplant: relation to ventricular expression and severity of rejection

To determine whether elevated plasma atrial natriuretic peptide (ANP) levels observed after cardiac transplant are related to ventricular ANP expression and/or the severity of rejection, 59 ambulatory patients with cardiac transplant underwent hemodynamic evaluation, endomyocardial biopsy, and plasma ANP sampling. Forty-two of the 59 patients had right ventricular (RV) biopsy specimens immunohistochemically stained for the presence of ANP. Plasma ANP levels were elevated (p < 0.0001) in transplant patients (172 +/- 12 pg/ml) compared to normal subjects (36 +/- 4 pg/ml). Sixty-four percent of transplant patients showed stainable RV ANP on endomyocardial biopsy. There was no significant difference in plasma ANP levels between patients with or without RV ANP. The degree of RV staining did not correlate with plasma ANP levels, degree of rejection, mean atrial or systemic pressures, or specific immunosuppressive regimen. Plasma ANP levels were higher in patients with moderate or severe rejection (237 +/- 17 pg/ml) compared to patients with mild or no rejection (163 +/- 12 pg/ml; p 0.03), but there was significant overlap of values. These data suggest that ventricular ANP secretion may account for some of the increase in plasma ANP levels in cardiac transplant patients. However, increased plasma ANP levels in some transplant patients who have no RV ANP and the lack of correlation between the amount of stainable RV ANP and plasma ANP levels suggest that other mechanisms are also likely responsible for plasma ANP elevations in this setting.

Endomyocardial biopsy--technical aspects experience and current status. An Indian perspective

Our study ellucidates the utility of endomyocardial biopsy (EMB) in various cardiac-muscle disorders seen in a tropical country like India. The procedure has been successfully performed in 501 patients (572 procedures) at our centre from April 1985 to December 1992. This included 60 infants and children. The indications were dilated cardiomyopathy (DCM) in 214, non-specific aortoarteritis in 91, rheumatic heart disease in 75, restrictive cardiomyopathy in 45, constrictive pericarditis in 14 and miscellaneous in 62 patients. There was no mortality, however, one patient developed cardiac tamponade and another sustained ventricular tachycardia requiring cardioversion. There was transient atrial fibrillation in six patients and all these had acute rheumatic heart disease. Transient complete heart block occurred in six patients with underlying left-bundle branch-block. Histological examination of EMB revealed myocarditis in 34/214 (15.4%) patients in DCM group and helped in following up these cases on immunosuppressive treatment. In the presence of restrictive haemodynamics it could identify amyloidosis in four patients. It was also helpful in differentiating between endomyocardial fibrosis and chronic constrictive pericarditis. In patients with non-specific aorto-arteritis significant histological changes of inflammatory myocarditis were observed in patients especially in congestive heart failure. Furthermore, it was helpful in identifying the nature of cardiac tumour in one patient. Its utility has also been evaluated in disorders, including rheumatic heart disease, peripartum cardiomyopathy and systemic disorders like systemic lupus erythematosis. Even in the absence of cardiac-transplant programmes at national level we have found EMB to be a useful investigation in a tropical country like India.

Selective activation of atrial natriuretic peptide in patients with myocardial infarction and mild left ventricular dysfunction

The purpose of this study was to investigate whether neurohumoral activation occurs in asymptomatic patients with acute myocardial infarction (AMI) and without clinical signs of heart failure. During the early phase of AMI (mean 8 days), the neurohumoral profiles of 60 patients (mean age 59 range 37 to 70) were examined. Blood levels of the following humoral parameters were measured: atrial natriuretic peptide (ANP), plasma renin activity, aldosterone and vasopressin. All patients underwent cardiac catheterization during hospitalization. Baseline hemodynamic characteristics identified left ventricular dysfunction (ejection fraction < or = 45% and/or left ventricular end-diastolic pressure > or = 15 mmHg) in 32 patients; the remaining 28 patients had normal hemodynamic parameters. In patients with AMI, plasma ANP levels differed significantly from control subjects (111 +/- 74 pg/ml vs. 53 +/- 18 pg/ml; P < 0.001). In patients with AMI and mild left ventricular dysfunction ANP levels were significantly increased when compared to patients with AMI and normal left ventricular function (129 +/- 73 pg/ml vs. 82 +/- 69 pg/ml; P < 0.001). The hemodynamic data showed a significant correlation with ANP only in patients with AMI and left ventricular dysfunction (EF% r = 0.42; LVEDP r = 0.44; P < 0.001). These data show that in patients with myocardial infarction and without heart failure, the atrial natriuretic peptide is the only neurohumoral system activated out of all neurohumoral systems tested in this population and its circulating levels are strictly related to the degree of left ventricular dysfunction.

Expression of proliferating cell markers in normal and diseased human hearts

Proliferating cell nuclear antigen (PCNA) myocyte expression and histopathologic features related to its occurrence were investigated in normal and diseased hearts of adult humans using both immunohistochemical and Western blotting techniques. Ki67 Western blotting was also performed in the same samples used for PCNA blotting. Two hundred seventy-one endomyocardial biopsies, and 15 adult, 1 embryonic and 2 fetal hearts were studied. The biopsies were from normal donor hearts (n = 71), patients with cardiomyopathy and myocarditis (n = 64), and patients with transplantation with (n = 106) and without (n = 30) acute rejection of any grade. The 15 hearts were from 1 heart donor, and from patients with cardiomyopathy (n = 5), valvular heart disease (n = 2), ischemic heart disease (n = 4), amyloidosis (n = 1) and transplantation with acute rejection (n = 2). The PCNA labeling index was plotted against myocyte hypertrophy, inflammatory infiltrates and binucleation index. The PCNA labeling index ranged from 2 to 9% in embryonic and fetal hearts. PCNA was expressed by 1 to 2% of myocyte nuclei in 12% of normal heart biopsies, 1 to 5% of myocyte nuclei in 28% of cardiomyopathy and myocarditis biopsies, and by up to 8% of myocyte nuclei in 53% of biopsies of patients with transplantation, independently of the presence and degree of acute rejection. In the latter biopsies and in myocarditis, some inflammatory cells also showed PCNA expression. PCNA positive myocytes were both mono- and binucleated, and there was no correlation between binucleation and PCNA labeling indexes. Ki67 and PCNA blotting confirmed immunohistochemical results.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide and circadian blood pressure regulation: clues from a chronobiological approach

A critical review of the data available in the literature today permits a better understanding of the multiple actions of atrial natriuretic peptide (ANP) on the cardiovascular system. Moreover, the results of chronobiological studies suggest a role for this peptide in the determination of the circadian rhythm of blood pressure (BP). ANP can affect BP by several mechanisms, including modification of renal function and vascular tone, counteraction of the renin-angiotensin-aldosterone system, and action on brain regulatory sites. A series of interrelated events may follow from very small changes in the plasma levels of ANP. The endpoints are blood volume and BP reduction, but they are rapidly offset (mainly by reactive sympathetic activation) as soon as blood volume or pressure is threatened. The circadian rhythms of BP and ANP are antiphasic under normal conditions and in essential hypertension. The loss in the nocturnal decrease of BP is accompanied by a comparable loss in the nocturnal surge of ANP in hypertensive renal failure and hypotensive heart failure. In the latter condition, BP and ANP variabilities correlate significantly both before and after therapy-induced functional recovery, independently of the mean BP levels. Autonomic function modulates the secretion of ANP, which seems more apt to determine only transient changes in BP levels, as suggested by the short half-life of the peptide and the buffering role of its clearance receptors. There is now sufficient evidence that ANP contributes to short-term control over BP and electrolyte balance, in contrast and in opposition to the renin-angiotensin-aldosterone system, which is involved primarily in long-term BP control. By interfering with other well-established neurohormonal factors, ANP appears to be an additional modulator of the circadian rhythm of BP.

Local contractile and growth modulators in the myocardium

Symptomatic congestive heart failure is the culmination of a process that evolves over many years. The long preclinical, or "incubation," period is the setting for a broad range of so-called local activities, including those involved in myocardial remodeling. Growth factors, cytokines, and vasoactive substances are central to this dynamic process, as are different populations of myocardial and circulating cells. The effects of angiotensin, endothelin, endothelium-derived relaxing factor, transforming growth factor-beta, and platelet-derived growth factor on myocardial structure, contractile function, and blood flow are outlined. The mechanisms involved in the activation of interleukin-1 and of tumor necrosis factor are examined within the context of the pathologic process.

Autocrine and paracrine mechanisms in the pathophysiology of heart failure

At the cellular and molecular level the transition to heart failure is a complex process that involves structural adaptation, not only of the heart, but of peripheral vasculature and renal tissues as well. Recent studies have suggested that autocrine, paracrine, and circulating biologically active mediators activate events that result in the concerted failure of adaptive mechanisms and the ultimate depression of cardiac myocyte function. Greater understanding of these local mechanisms in the future may lead to drug therapies that can selectively block these mechanisms and prevent the progression from compensation to overt heart failure.

Decreased plasma atriopeptin response to volume-overloading maneuvers and exercise after atriopulmonary anastomosis of Fontan

Atriopulmonary anastomosis results in a chronic right atrial pressure-volume overload. Water and salt retention is a frequent clinical observation in patients after atriopulmonary anastomosis. The purpose of this study was to examine if this could be related to an inability to increase already elevated circulating atriopeptin (ANP) in response to central volume-overloading conditions. Eighteen patients (mean age 16 +/- 6 years) with an atriopulmonary anastomosis underwent routine cardiac catheterization during which a 5-minute head-down 10 degrees tilt was performed. Peripheral venous and right atrial blood samples were obtained under basal conditions, and after tilting and angiography for determination of ANP concentrations. At a different time, circulating ANP levels were measured during a maximal graded exercise protocol. Increased circulating ANP concentrations were found under basal conditions (114 +/- 10 pg/ml). Tilting and cardioangiography resulted in significant increases in mean atrial pressure (basal: 12 +/- 0.7 mm Hg; tilt: 13.4 +/- 0.63 mm Hg; after angiography: 15.8 +/- 0.8 mm Hg), but not in atrial or peripheral ANP. Compared with the expected threefold increase in plasma ANP induced by maximal exercise in healthy control subjects, only a slight (0.25-fold) increase was found in patients. These observations suggest a reduced stimulus-release response after atriopulmonary anastomosis, which could be related to a loss of atrial stretch receptor sensitivity, achievement of the limit for maximal right atrial secretion, or an alteration in right atrial compliance, or a combination.

Localization of brain and atrial natriuretic peptide in human and porcine heart

We have compared the localization of brain and atrial natriuretic peptide-like immunoreactivity in human and porcine hearts, using immunohistochemical techniques at both the light and ultrastructural level and specific antisera to amino-(cardiodilatin) and carboxy-terminal regions of the atrial natriuretic precursor molecule and to brain natriuretic peptide. Atrial myocardial cells in human fetal, normal adult and failing explanted hearts, displayed immunoreactivity for both brain and atrial natriuretic peptide-like sequences. At the subcellular level, brain natriuretic peptide-, cardiodilatin- and alpha-atrial natriuretic peptide-like immunoreactivity were co-localized to secretory granules in atrial myocardial cells. Immunoreactivity was also detected in the left (64%) and right ventricular free walls (23%) of 22 failing explanted hearts, but not in donor cardiac tissues. A gradient of natriuretic peptide immunostaining was observed across ventricular free walls and immunoreactivity for both natriuretic peptide sequences co-localized to secretory granules in a subpopulation of myocardial cells, concentrated in subendocardial regions of the ventricular walls. Brain and atrial natriuretic peptide-like immunoreactivity were also demonstrated in porcine atrial myocardium and cells of the ventricular conduction system. The parallel distribution of cardiac brain and atrial natriuretic peptide-like immunoreactivity suggests a dual regulation and co-storage of the natriuretic peptides in human and porcine hearts.

Consistent changes in the circadian rhythms of blood pressure and atrial natriuretic peptide in congestive heart failure

We demonstrated in previous works that the circadian rhythms of blood pressure (BP) and atrial natriuretic peptide (ANP) are antiphasic in normal subjects and in essential hypertension. The aim of the present study was to assess the circadian rhythms of BP and ANP in 20 patients with stable congestive heart failure (CHF), divided into two groups of 10 according to their New York Heart Association functional class. A matched control group of 10 normal volunteers was also studied. Noninvasive BP monitoring at 15-min intervals was performed for 24 h. Peripheral blood samples were also obtained at 4-h intervals starting from 08:00 h. The mean (+/- SEM) circadian mesors of ANP plasma levels were 13.4 +/- 1.7 pmol/L in the control group, 28.6 +/- 2.4 pmol/L in the group of 10 patients in class II, and 81.5 +/- 12 pmol/L in the group of 10 patients in class III-IV. In normal subjects, plasma ANP concentration was highest at 04:00 h (21.5 +/- 2.7 pmol/L) and lowest at 16:00 h (8.8 +/- 2.4 pmol/L; p less than 0.01). Both groups of patients with CHF showed no significant circadian change in the plasma levels of ANP and also a significantly blunted circadian rhythm of BP. Cosinor analysis confirmed the loss of the circadian rhythms of ANP and BP in CHF patients. Our findings support the existence of a causal relationship between the circadian rhythms of ANP and BP.