Evidence for association of a common variant of the endothelial nitric oxide synthase gene (Glu298-->Asp polymorphism) to the presence, extent, and severity of coronary artery disease

BACKGROUND

Genetic variants of endothelial nitric oxide synthase (eNOS) could influence individual susceptibility to coronary artery disease.

OBJECTIVE

To assess whether Glu298-->Asp polymorphism of the eNOS gene is associated with the occurrence and severity of angiographically defined coronary artery disease in the Italian population.

METHODS

Polymerase chain reaction/restriction fragment length polymorphism analysis was done to detect the Glu298-->Asp variant of the eNOS gene in 201 patients with coronary artery disease and 114 controls. The severity of coronary artery disease was expressed by the number of affected vessels and by the Duke scoring system.

RESULTS

The frequencies of the eNOS Glu/Glu, Glu/Asp, and Asp/Asp genotypes in the coronary artery disease group were significantly different from those of controls (45.3%, 38.8%, and 15.9% v 42.1%, 51.8%, and 6.1%, respectively; chi2 = 8.589, p = 0.0136). In comparison with subjects who had a Glu298 allele in the eNOS gene, the risk of coronary artery disease was increased among Asp/Asp carriers (odds ratio 2.9, 95% confidence interval 1.2 to 6.8, p = 0.01) and was independent of the other common risk factors (p = 0.04). There was a significant association between the eNOS Glu298-->Asp variant and both the number of stenosed vessels (mean (SEM), 2.3 (0.1) for Asp/Asp v 1.9 (0.1) and 1.8 (0.1) for Glu/Glu and Glu/Asp, respectively; p = 0.01) and the Duke score (56.1 (3.1) for Asp/Asp v 46.7 (2.0) and 46.1 (1.9) for Glu/Glu and Glu/Asp, respectively; p = 0.02).

CONCLUSIONS

Glu298-->Asp polymorphism of the eNOS gene appears to be associated with the presence, extent, and severity of angiographically assessed coronary artery disease.

No variation in Hsp70 mRNA level during cardiac surgery in pediatric patients evaluated by semiquantitative RT-PCR

We evaluated mRNA expression of the heat shock protein gene, Hsp70-1, by means of a semiquantitative RT-PCR in atrial tissue specimens from pediatric patients collected before and after cardiopulmonary bypass surgery for congenital heart diseases, to see whether surgical stress may affect the expression level of this mRNA. We studied thirty nine pediatric patients (aged 3 months to 15 years) undergoing surgical correction of congenital heart malformation. Twenty-one patients were affected by the tetralogy of Fallot, two by combined atrioventricular septal defects, six by ventricular septal defect, three by atrial septal defect, two by atrioventricular canal defect, two by pulmonary valve stenosis, one by mitral insufficiency, and one by double-outlet right ventricle. Our results showed no significant changes in the Hsp70-1 mRNA expression in atrial tissue of patients before and after cross-clamping (the mean relative expression after cross-clamping was 1.0+/-0.6 compared to the baseline value). Furthermore, no significant correlations were observed between cross-clamping time and temperature, cardiopulmonary bypass time and mRNA variation. Our study suggests that, during cardioplegia, myocardial tissue does not have an appropriate adaptive response to surgical stress.

Molecular characterization of chromosome 22 deletions by short tandem repeat polymorphism (STRP) in patients with conotruncal heart defects

The haploinsufficiency of chromosome 22q11.2 can cause both DiGeorge and velocardiofacial syndromes, both of which are characterized by conotruncal heart defects as well as a wide range of other extracardiac anomalies. Several studies have demonstrated that approximately 10-20% of patients with conotruncal heart defects have a 22q11.2 deletion. In clinical laboratories, the deletion is usually detected by fluorescent in situ hybridization (FISH). We set up a polymerase chain reaction-based non-radioactive method for molecular analysis of the 22q11.2 region in conotruncal cardiac patients with conotruncal defects. Sixty-four children with conotruncal defects and their parents were genotyped by polymerase chain reaction, using fifteen polymorphic markers. We identified nine deletions (confirmed by FISH): eight were "de novo" and one familial, maternally inherited. Six deletions were of paternal and three of maternal origin. There were seven deletions of 3 Mb and the other two were of 1.5 Mb. This method is a cost-effective means of characterizing the 22q11.2 region and it can be applied for a rapid screening of 22q11.2 deletion in patients at risk. In agreement with previously published data, we found no correlation between the sizes and the parental origin of deletions and cardiac or extra-cardiac phenotypes.

Increase in circulating levels of cardiac natriuretic peptides after hormone replacement therapy in postmenopausal women

The mechanisms that mediate the cardioprotective action of steroid hormones in postmenopausal women are poorly understood. To study the inter-relationship between female steroid hormones and cardiac natriuretic peptides, plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were measured in postmenopausal women, both before and after oestrogen replacement therapy. A total of 22 healthy postmenopausal women (mean age 51.9+/-4.6 years) were enrolled in the study; all had been postmenopausal for at least 1 year and all reported climacteric symptoms accompanied by increased levels of follicle-stimulating hormone (>30 m-i.u./ml) and luteinizing hormone (>20 m-i.u./ml), and a reduction in oestradiol (<25 pg/ml). All women were given hormone replacement therapy with transdermal oestradiol, either patch (50 microg/24 h) or gel (1 mg/day), cyclically combined with oral dihydrogesterone (10 mg/day for 12 days/month, on days 19-30 of the month). ANP and BNP were measured directly in plasma samples with specific and sensitive immunoradiometric assays before and after hormone replacement therapy (transdermal oestradiol combined with oral dihydrogesterone). Body weight, arterial blood pressure and echocardiographic examination values did not change after hormone replacement therapy. As expected, serum oestradiol increased significantly and gonadotropins decreased as an effect of the hormone replacement therapy. On average, both ANP and BNP had increased significantly after 3 months of hormone replacement therapy [ANP: before treatment, 17.6+/-9.6 pg/ml; after, 23.6+/-5.6 pg/ml (P=0.0173); BNP: before treatment, 12.6+/-10.2 pg/ml; after, 19.8+/-14.0 pg/ml (P<0.0001)]. Our study indicates that hormone replacement therapy for a period of 3 months induces a rise in the circulating levels of cardiac natriuretic hormones in postmenopausal women. Our data also suggest the working hypothesis that cardiac natriuretic peptides may play an important role in mediating the cardioprotective effects of female steroid sex hormones in women throughout life.

[An exceptional case of hypersensitivity to actinomycin D. Case report and review of the literature]

We report the first case, to our knowledge, of an allergic attack following the administration of Act-D in a 9 year old boy, affected by orbit embrional rabdomyosarcoma. The boy was given most operative therapy according to RMS 96 protocol, IRS group IIb, with Actinomicin D (Act-D), Vincristine and Ifosfamide and RT. Immediately after the beginning of chemotherapy the boy presented with an asthma-like attack (dyspnoea and asthenia), supposed to be a side effect of Ifosfamide administration regressed by intravenous bolus of hydrocortisone and chlorphenamine. In the second chemotherapy cycle concurrent with RT, the Act-D preceded the administration of ifosfamide. Subsequently to the administration of Act-D and RT, without premedication, the boy presented with a face erythema and asthma like attach. Post operative chemotherapy was achieved with no further allergic side effect using premedication with hydrocortisone and chlorphenamine. The boy is now 13 years old, alive and disease free at a three years follow-up.

Up-regulation of 'clearance' receptors in patients with chronic heart failure: a possible explanation for the resistance to biological effects of cardiac natriuretic hormones

BACKGROUND

Three specific receptors for the cardiac natriuretic peptide system have been identified to date. Down-regulation of the biologically active binding sites (i.e. NPR-A and NPR-B) could explain the blunted response to cardiac natriuretic hormones observed in heart failure (HF), but not the increased metabolic clearance rate. Variations in the ratio between biological and clearance (NPR-C) receptors in target tissue may explain this increase.

AIM

The aim of this study was to investigate the regulation of NPR-C receptors on platelets, in patients with HF.

METHODS

Eighteen patients with HF (NYHA class: I-II, n=8; III-IV, n=10) and 18 age-matched healthy subjects were studied. The affinity constant (K(d)) and density (B(max)) of binding sites were derived by saturation assays on platelet suspensions using 125I-ANP as radioligand.

RESULTS

B(max) increased as a function of the severity of disease: 21.3+/-3.3 fmol/10(9) cells in class III-IV, 11.7+/-2.2 in class I-II, and 11.6+/-1.1 in controls, respectively (P=0.0179 for class III-IV vs. controls and P=0.0451 vs. NYHA I-II).

CONCLUSIONS

The increase in density of 'clearance' receptors in severe HF is theoretically consistent with the reduction in cardiac natriuretic peptide biological activity, as well as the increase in metabolic clearance rate. This suggests that clearance receptor blockade may be of potential therapeutic value in HF.

Evidence for DNA damage in patients with coronary artery disease

According to the "monoclonal hypothesis" of atherosclerosis, several studies suggest that cancer and atherosclerosis may have several fundamental biological mechanisms in common. Therefore, an increase in the mutation rate may be involved in the pathogenesis of atherosclerotic plaques. The aim of the study was to verify the presence of chromosomal damage in peripheral blood lymphocytes in patients with coronary artery disease by using micronucleus (MN) test, a reliable biomarker in genetic and cancer risk assessment. Subjects included 53 patients with documented coronary ischemic heart disease (group I); 10 patients with valvular heart disease in absence of atherosclerotic lesions of the coronary arteries (group II) and 16 healthy subjects, age- and sex-matched (group III) were studied as controls. For each subject, two separate cultures were performed and 1000 binucleated cells were scored for the evaluation of MN frequency. The mean (+/-S.E.M.) of MN frequency were 11.9+/-1.7, 5.9+/-1.2 and 3.6+/-0.7 in groups I, II and III, respectively. The MN frequency of group I was significantly higher than that of group III (P=0.02). In group I, MN frequency increased with the number of affected vessels (6.3+/-0.7, 13.9+/-1.6, 14.9+/-5.3 for one-, two-, and three-vessel disease, respectively). Scheffe's test showed that MN frequency was significantly higher in two-vessel compared with one-vessel disease (P=0.0077). Moreover, a positive relationship was found between MN levels and the severity of the disease, calculated by the Duke scoring system (R=0.28, P=0.032), as well as the systolic blood pressure (R=0.34, P=0.009). These results suggest that coronary artery disease in humans is a condition characterized by an increase of DNA damage, positively correlated with the severity of the atherosclerotic disease.

Endothelin-1, endothelin-1 receptors and cardiac natriuretic peptides in failing human heart

Endothelin (ET)-1 is a potent vasoconstrictor peptide produced in the myocardium that can exert important effects on cardiac myocyte growth and phenotype; cardiac natriuretic peptides (ANP and BNP) are known to act as physiological antagonists of ET-1. In this study a comparative determination of ET-1 receptors and of the local productions of ET-1 and of ANP and BNP was made in different sites of failing and nonfailing hearts. Tissue from right and left atrium, right and left ventricle and interventricular septum from seven adult heart transplant recipients with end-stage idiopathic dilated cardiomyopathy (functional class III and IV, with ejection fraction < 35%) and from four postmortem subjects without cardiac complications was analyzed. In failing hearts we observed a tendency to increase of density of binding sites, most evident in left ventricle (62.6+/-22.6 fmol/mg protein vs. 29.0+/-3.3, mean +/- SEM, p = ns). A prevalence of ET-A subclass, observed in all samples, resulted more pronounced in failing hearts where this increase, found in all the cardiac regions, was more evident in left ventricle (p = 0.0007 vs nonfailing hearts). The local concentrations of ET-1, ANP and BNP resulted significantly increased in failing hearts with respect to controls in all sides of the heart. In failing hearts we have observed a tendency to increase in endothelin receptor density mainly due to a significant upregulation of ET-A subtype and a parallel increase of the tissue levels of ANP, BNP and ET-1 indicating an activation of these systems in heart failure.

Plasma brain natriuretic peptide measured by fully-automated immunoassay and by immunoradiometric assay compared

The clinical relevance of measuring plasma brain natriuretic peptide (BNP) is well-known, especially in patients with heart failure. Recently, a new method for measuring BNP, called TRIAGE, has been developed which can be used for point-of-care testing of patients with congestive heart failure. The aim of the present study is to compare the analytical performance of this fully-automated method to that of an immunoradiometric assay (IRMA), routinely used to measure BNP. The TRIAGE method is a non-competitive immunofluorometric assay which uses two different binding phases, specific for two different epitopes of the BNP amino acid chain, to form a sandwich with the specific ligand (i.e., BNP). A polyclonal antibody is included in the fluorescent immunoassay reagents which are contained in the assay devices and a monoclonal antibody is immobilized in the detection lane of the assay device. The imprecision of the TRIAGE method was approximately 12% for BNP concentrations in the normal range and about 18% for BNP concentrations above the normal range. The mean reading time of the TRIAGE method was 14.5 +/- 8.6 min. A close linear relationship was found between the BNP values measured with the two methods (TRIAGE = 24.6+0.933 IRMA; r = 0.932, n = 83). The TRIAGE method is indicated for BNP assay in ambulatory and coronary or emergency units, where usually only a few samples (preferentially whole blood samples) must be measured in a short time. The IRMA method should be preferred for pathophysiological studies, requiring the highest degree of precision and sensitivity for simultaneous measurement of several stored plasma samples or tissue extracts.

Clinical relevance of cardiac natriuretic peptides measured by means of competitive and non-competitive immunoassay methods in patients with renal failure on chronic hemodialysis

Increased levels of cardiac natriuretic peptides in patients undergoing hemodialysis may be a marker of cardiomyopathy and in consequence may be suitable prognostic indicators for the risk of development of cardiac disease. We measured plasma levels of ANP, BNP, proANP(1-98) and proBNP(1-76)-related peptides with some competitive and non-competitive immunoassay methods in patients with renal failure on chronic hemodialysis in order to compare the analytical performances of these methods and to evaluate the clinical usefulness of each assay for patients with chronic renal failure. ANP and BNP values significantly decreased after hemodialysis (on average, ANP by 36% and BNP by 16%); while all proANP and proBNP values tended to increase, but only proANP(1-30) (by 14.4%) and Nt-proBNP (by 9.5%) significantly. Although significant correlations were found among all the circulating levels of cardiac peptides studied, N-terminal pro-peptides correlated better among themselves than with ANP and BNP; ANP was only slightly correlated with all the other peptides, the only exception being BNP. Only BNP levels significantly increased according to the degree of ventricular hypertrophy and/or ventricular function in patients with chronic renal failure. The ANP assay is preferable in physiological and clinical studies for the rapid changes in atrial pre-load. BNP would be more useful in the follow-up of cardiac complications in patients with end-stage renal disease on regular hemodialysis. The assays of N-terminal proANP(1-98)-and proBNP(1-76)-related peptides proved to be of limited use, because they were not able to detect acute changes in pre-load during hemodialysis and were less useful than BNP levels as markers of ventricular hypertrophy and/or functional cardiac impairment.

Possibility of age regulation of the natriuretic peptide C-receptor in human platelets

Natriuretic peptide binding sites on platelets have been hypothesized to act as clearance receptors; however, there is no clear definition of the function of this receptor. The aim of the study was: 1) to characterize natriuretic peptide receptors in human platelets by original competition study; 2) to evaluate a possible age modulation of these binding sites, since a delayed clearance of ANP in the elderly has been observed. The binding of 125I-ANP to intact platelets was completely inhibited by h-ANP, h-BNP, h-CNP and c-ANP, the selective ligand of the clearance receptor. IC50 values were 0.089+/-0.029, 0.703+/-0.104 and 1.19+/-0.13, 3.84+/-0.04 nmol/l, mean+/-SE, respectively (p<0.001 for IC50 value of h-ANP compared to the other natriuretic peptides). This observation on the receptor selectivity of natriuretic peptides in human platelets provides new evidence for the presence of the clearance receptor on platelets. In control subjects the Kd was 34.6+/-4.0 pmol/l and Bmax 13.6+/-0.92 fmol/10(9) platelets (mean+/-SE), (no.=46, mean age 41.7+/-2.1 years). Bmax was significantly reduced in older subjects (no.=25, mean age 53.2+/-1.5 years) with respect to the younger group (no.=21, mean age 28.0+/-0.87 years): 11.4+/-1.1 vs 16.1+/-1.4 fmol/10(9) cells, p=0.0096, respectively; moreover, a significant inverse relationship between Bmax and the subject's age was observed. This observation suggests a possible reduction of the natriuretic peptide clearance with aging, associated to a significant increase of plasma levels of natriuretic peptides.

Measurement of cardiac natriuretic hormones (atrial natriuretic peptide, brain natriuretic peptide, and related peptides) in clinical practice: the need for a new generation of immunoassay methods

BACKGROUND

Cardiac natriuretic hormones (CNHs) are a family of related peptides, including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and other peptides derived from the N-terminal portion of the proANP and proBNP peptide chains. Assays for cardiac natriuretic peptides have been proposed to help assess clinical conditions associated with expanded fluid volume. In particular, the assays can be useful for distinguishing healthy subjects from patients in different stages of heart failure. Measurements of these hormones have also been considered for prognostic indicators of long-term survival in patients with heart failure and/or after acute myocardial infarction. The different CNHs differ in their production/secretion patterns and have different clearance rates. Furthermore, there are numerous proposed assay configurations for each of these hormones, and it is not clear which assay provides the best pathophysiological and/or clinical information.

APPROACH

Here we review recent studies concerning the competitive (such as RIA, enzyme immunoassay, or luminescence immunoassay) and noncompetitive immunoassays (such as two-site IRMA, ELISA, or immunoluminometric assay) for the different cardiac natriuretic peptides to compare the analytical characteristics and clinical relevance of assays for the different CNHs and the different assay formats.

CONTENT

Developing sensitive, precise, and accurate immunoassays for cardiac natriuretic peptides has been difficult because of their low concentrations (on average, approximately 3-6 pmol/L) in healthy subjects and because of their structural, metabolic, and physiological characteristics. Competitive assays have historically suffered from lack of sensitivity and specificity for the biologically active peptides. These usually require tedious extraction procedures prior to analysis. Recently, immunometric assays have been developed that have improved sensitivity and specificity; it appears these will be the methods of choice.

SUMMARY

To date, there is no consensus on the best assay procedure of cardiac natriuretic peptides. To facilitate widespread propagation of determination of these hormones in routine clinical practice, it will be necessary to study the new generation of noncompetitive immunometric methods that are less time-consuming and more sensitive and specific. Although several studies suggest that BNP exhibits better clinical utility than the other CNHs, more studies examining multiple CNHs in the same cohorts of patients will be necessary.

Turnover studies on cardiac natriuretic peptides: methodological, pathophysiological and therapeutical considerations

Cardiac natriuretic peptide hormones (ANP and BNP) are synthesized and secreted by the heart, producing several biological effects, such as natriuresis, vasorelaxation, hypotension, and neuromodulation. Extensive studies conducted in both animals and humans have documented that cardiac natriuretic peptides (CNPs) are secreted into the circulatory system via the coronary sinus into the right atrium, and then rapidly degraded and removed from the blood by plasma proteases and specific clearance receptors. Usually, studies of CNPs kinetics have been carried out following an experimental protocol in which labeled or unlabeled hormone is administered (by constant infusion or bolus injection) and the corresponding concentration of the hormone is measured in peripheral venous blood. However, when a uniform intravascular concentration throughout artero-venous vessels is lacking due to the very rapid clearance of the substance being studied (such as CNPs), the classical compartmental or none compartmental approach may not be suitable for interpreting the experimental data. In this case, a more physiological circulatory model, which does not assume a uniform intravascular distribution of the hormone and comprises several anatomo-functional blocks arranged in a series and supplied by the same flow (cardiac output) should be adopted. Different experimental designs (infusion or bolus injection) as well as multiple sampling sites (aorta and pulmonary artery, inferior vena cava, femoral vein) were used in ANP kinetic studies. Using a circulatory approach, ANP has been demonstrated to be rapidly distributed and degraded; in healthy subjects about 50% of ANP secreted into the right atrium is extracted by the peripheral tissues during the first pass throughout the body. Since CNPs have important fluid-volume regulatory features, it has been postulated that they also play a key role in volume homeostasis in several pathophysiological states, such as congestive heart failure. Indeed, a markedly altered degradation and distribution of ANP in patients with cardiac failure who show a resistance to its natriuretic effects, even in those on the early stage of clinical disease, whose CNPs plasma levels are in the normal range, have been demonstrated. Recent studies indicate that some drugs, by inhibiting the degradation of CNPs by plasma proteases and can thus affect CNP kinetics, may be useful in the treatment of arterial hypertension and cardiac failure.

Applicability of a circulatory model for determining the parameters of kinetics of endogenously produced compounds

The applicability of circulatory model approach for determining the kinetic parameters of endogenously produced substances has been demonstrated based on the assumption that the behaviour of newly produced molecules of a compound inside its production spaces is the same as that of the molecules returned due to recirculation of blood. While extraction and transmission parameters can be estimated by using tracer data, total mass cannot be determined without additional information. This information could be obtained from data of some suitable metabolite by using double tracer method. Circulatory model is especially suitable for studies of substances with a fast kinetics and renewal if blood (plasma) flow is measured independently.

Measurement of brain natriuretic peptide in plasma samples and cardiac tissue extracts by means of an immunoradiometric assay method

We evaluated the analytical characteristics and clinical usefulness of a commercial immunoradiometric assay (IRMA) kit for brain natriuretic peptide (BNP). Mean (+/-SD) plasma BNP concentrations measured in 129 normal subjects were 2.9+/-2.7 pmol/l (median 2.2 pmol/l; range 0.1-12.4 pmol/l). The mean (+/- SD) value observed in healthy men (2.1 +/- 2.0 pmol/l, n = 49) was significantly (p=0.0009) different to that found in women (3.4 +/- 2.9 pmol/l, n=80). A positive relationship (R=0.214, p=0.0174) was found between BNP values and age. In 65 patients with cardiac diseases, BNP levels increased with the progression of clinical severity of disease; patients with more severe disease [NYHA functional class III-IV, mean (+/- SD) BNP +/- 254 +/- 408 pmol/l, n=22] showed significantly (p<0.0001) increased values compared to patients with mild symptoms of disease (NYHA functional class I-II, mean (+/- SD) BNP=19.6 +/- 17.2 pmol/l, n=43). Furthermore, in 32 patients with chronic renal failure, greatly increased (p<0.0001) BNP values were found both before (mean +/- SD=88. 1+/- 111.1 pmol/l) and after haemodialysis (mean +/- SD=65.6 +/- 76.7 pmol/l), with a significant reduction after haemodialysis (p=0.0004) compared to pre-haemodialysis. The mean (+/- SD) BNP value found in atrial extracts collected during aorto-coronary bypass operations in 15 patients was 14.5 +/- 51.9 pmol/g of cardiac tissue. Moreover, the mean (+/- SD) tissue levels of BNP in 7 heart transplant recipients were 128.4 +/- 117.2 pmol/g of cardiac tissue in atrium, 68.4 +/- 76.7 pmol/g in ventricle, and 10.9 +/- 8.5 pmol/g in interventricular septum. Finally, BNP values found in cardiac tissues of two subjects collected at autopsy were considerably lower (on average 1/1000) than those observed in cardiac tissues of patients with cardiac diseases. The IRMA method for BNP determination evaluated in this study showed a good degree of sensitivity, precision and practicability. Therefore, this method should be a reliable tool for the measurement of plasma BNP levels for both experimental studies and routine assay.

Ten-day schedule oral etoposide therapy in advanced childhood malignancies

PURPOSE

The activity of etoposide (VP-16) has been demonstrated to be schedule-dependent. Several studies have been conducted on the efficacy and safety of different schedules of VP-16 both in adults and in children, but the optimal schedule has not been determined.

METHODS

In the current study, the feasibility and effectiveness of prolonged oral VP-16 in children with high-risk malignancies were evaluated. Between April 1995 and February 1999, 15 pretreated patients with high-risk tumors received oral VP-16. The schedule of therapy was oral VP-16 50 mg/m2/day for 10 consecutive days and 1-week interval between cycles. Therapy was stopped after 1 year of treatment or at time of progressive disease or possible surgery. All patients had received parenteral VP-16 in their earlier chemotherapy.

RESULTS

Twelve patients were evaluable for tumor response. After 2 to 4 months of treatment, one patient had complete remission (CR), two had partial response (PR), two had minor response (MR), two had mixed response (MxR), three had stable disease (SD), and two had progressive disease (PD). A useful palliative effect was noted in patients with stable disease. In three patients, oral VP-16 was administered for maintenance therapy. After an average follow-up of 27.5 months (range, 7-41 months), five patients are alive without disease (in three, total surgery was performed after VP-16 therapy) and three patients are alive with disease. Six patients died of progressive disease, and one died of promyelocytic leukemia. One patient had Grade 34 thrombocytopenia; in the remaining patients, no acute toxicity was observed during treatment.

CONCLUSIONS

This schedule of oral VP-16 produced CRs, PRs, and MRs in medulloblastoma, neuroblastoma, teratocarcinoma, and ependymoma. Stable disease was observed in three patients, one with an Askin tumor, one with medulloblastoma, and one with hepatoblastoma. Given the possible leukemogenic risk, this schedule should be used as a palliative form of therapy or in patients with poor prognosis..

Genetic instability and atherosclerosis: can somatic mutations account for the development of cardiovascular diseases?

Several observations suggest that cancer and atherosclerosis may entail fundamentally common biological mechanisms. The accumulation of lipids and the proliferation of smooth muscle cells (SMCs) are the main histological features of sclerotic plaque formation. The most prominent theory concerning the pathophysiological mechanisms of atherosclerotic plaque formation is the "inflammatory response to injury" hypothesis, which states that SMC proliferation is an inflammation-fibroproliferative reaction to different insults to the artery wall. However, recent evidence suggests that alterations at the DNA level may contribute significantly to the development of the disease. In accordance with these findings, the "monoclonal" hypothesis of atherosclerosis has been suggested. This hypothesis proposes that atherosclerosis begins as a mutation or viral infection, transforming a single, isolated smooth muscle cell into the progenitor of a proliferative clone, as seen in carcinogenesis. Studies of DNA damage in atherosclerotic tissues are lacking. Biological evidence for the hypothesis that cancer and atherosclerosis may share pathological mechanisms is discussed, emphasizing the need to perform studies investigating the involvement of somatic mutations in heart diseases.

A rapid procedure for the quantitation of natriuretic peptide RNAs by competitive RT-PCR in congenital heart defects

We report an original application of quantitative reverse transcription-polymerase chain reaction (Q.RT-PCR) for the evaluation of atrial natriuretic factor (ANF), brain natriuretic peptide (BNP) and beta-actin mRNA in small atrial samples (10-15 mg). A fixed amount of total RNA was simultaneously reverse transcribed and amplified with dilutions of a competitor RNA fragment used as a control. We constructed a single synthetic RNA competitor for ANF, BNP and beta-actin. The competitors and targets shared the same primer sequences but yielded PCR products of different sizes. We have investigated ANF, BNP and beta-actin gene expression in patients affected by congenital heart defects (CHD) during the surgical correction of the defect. We collected a right atrial sample from each patient before the start of cardiopulmonary bypass. We studied 14 patients affected by tetralogy of fallot (no. 6), complex CHD (no. 4), and ventricular septal defect (no. 4). The results indicate that the Q.RT-PCR represents a simple, highly specific, non radioactive procedure for the quantification of natriuretic peptide gene expression and is particularly suitable for evaluation of gene expression in small myocardial samples. Our data also suggest that: 1) there is a significant relationship between the levels of ANF, BNP and beta-actin mRNA and the type of CHD; 2) the levels of BNP mRNA are more variable than ANF; 3) the beta-actin seems to be unsuitable for normalising cardiac gene expression in CHD because mRNA basal levels of this protein vary greatly among patients with different type of CHD.

Pathophysiologic relevance of measuring the plasma levels of cardiac natriuretic peptide hormones in humans

Cardiac natriuretic peptides (ANP, BNP, and biologically active peptides of the N-terminal proANP1-98) are differently regulated in their production/secretion patterns and clearance rates; consequently, the assay for these peptides may provide complementary (or even different) pathophysiological and/or clinical information. The assay for cardiac natriuretic peptides has been utilized in clinical conditions associated with expanded fluid volume. In particular, this assay can be useful in discriminating between normal subjects and patients in different stages of heart failure and can also be considered a prognostic indicator of long-term survival in patients with heart failure and/or after acute myocardial infarction. Non-competitive immunometric assays (such as two-site IRMAs), even if more expensive, seem to be preferable to RIAs for routinary assay of cardiac peptide hormones because they generally have a better degree of sensitivity, accuracy, and precision.

[Physiological significance and clinical utility of analytical methods for cardiac natriuretic peptides]

It was well-established that the heart has an endocrine function because it is able to synthesize and secrete a family of related peptide hormones (known as cardiac peptide hormones) with potent diuretic, natriuretic and with complex interactions with the hormonal and nervous systems. Cardiac natriuretic peptides (ANP, BNP, and biologically active peptides of the N-terminal proANP1-98) are differently regulated in their production/secretion patterns and clearance rates; consequently, the assay for these peptides may provide complementary (or even different) pathophysiological and/or clinical information. The assay for cardiac natriuretic peptides has been utilized in clinical conditions associated with expanded fluid volume. In particular, this assay can be useful in discriminating between normal subjects and patients in different stages of heart failure and can also be considered as a prognostic indicator of long-term survival in patients with heart failure and/or after acute myocardial infarction. Non-competitive immunometric assays (such as two-site IRMAs), even if more expensive, seem to be preferable to RIAs for routinary assay of cardiac peptide hormones because they generally have a better degree of sensitivity, accuracy, and precision. The technical characteristics and the potential clinical usefulness of some of the methods for measuring these peptides are reviewed.

Circulating levels of cardiac natriuretic hormones measured in women during menstrual cycle

Alterations in fluid and electrolyte balance represent a common complaint by women during different stages of the menstrual cycle; however, conflicting results concerning the possible role of plasma Atrial Natriuretic Peptide (ANP) modifications during the menstrual cycle have been reported. This may be due to differences in assay methods or in the clinical protocol adopted. Moreover, possible variations in plasma Brain Natriuretic Peptide (BNP) levels during the menstrual cycle have not been studied. We measured the plasma levels of ANP and BNP by means of two highly sensitive and specific immunoradiometric assay (IRMA) methods in 19 normal women without premenstrual symptoms, in order to evaluate whether significant modifications of these hormones are present during the menstrual cycle. Because it is well-known that circulating levels of cardiac hormones show great variations in normal subjects due to their rapid plasma half lives, blood samples were collected at 2.5-min intervals over a 15-min period on the 5th and 24th days of the cycle. The mean (+/-SD) values of ANP (follicular phase=15.1+/-8.7 pg/ml; luteal phase=14.8+/-9.5 pg/ml) and of BNP (follicular phase=13.0+/-15.0 pg/ml; luteal phase=11.2+/-11.4 pg/ml) did not show significant variations during the menstrual cycle. Moreover, the variability of ANP values (CV=24.8+/-13.2%) was significantly higher (p=0.0318) than that of BNP values (CV=16.5+/-8.9%), and a significant correlation was found between the mean ANP and BNP values of the individual women studied (R=0.407, p=0.0437). The values of estradiol, progesterone, LH, FSH and prolactin did not correlate with the ANP or BNP values. In conclusion, our results indicate that circulating levels of cardiac hormones do not show any significant modifications during the menstrual cycle in healthy women.