Association between low-activity serotonin transporter genotype and heroin dependence: behavioral and personality correlates

In previous studies, serotonin (5-HT) system disturbance was found involved in a variety of behavioral disorders, psychopathologies, and substance use disorders. A functional polymorphism in the promoter region of the human serotonin transporter gene (5-HTTLPR) was recently identified and the presence of the short (S) allele found to be associated with a lower level of expression of the gene, lower levels of 5-HT uptake, type 2 alcoholism, violence and suicidal behavior. In the present study, 101 heroin addicts (males, West European, Caucasians) and 101 healthy control subjects matched for race and gender, with no history of substance use disorder, have been genotyped. Aggressiveness levels were measured in both heroin addicts and controls utilizing Buss-Durkee-Hostility-Inventory (BDHI). Data about suicide attempt and violent criminal behavior in subject history have been collected. The short-short (SS) genotype frequency was significantly higher among heroin dependent individuals compared with control subjects (P = 0.025). The odds ratio for the SS genotype versus the long-long (LL) genotype frequency was 0.69, 95% Cl (0.49-0.97), when heroin addicts were compared with healthy controls. The SS genotype frequency was significantly higher among violent heroin dependent individuals compared with addicted individuals without aggressive behavior (P = 0.02). BDHI mean total scores and suspiciousness and negativism subscales scores were significantly higher in SS individuals, in comparison with LL subjects, among heroin addicts. No association was found between SS genotype and suicide history. Our data suggest that a decreased expression of the gene encoding the 5-HTT transporter, due to "S" promoter polymorphism, may be associated with an increased risk for substance use disorders, particularly in the subjects with more consistent aggressiveness and impulsiveness.

Varicocele and sport in the adolescent age. Preliminary report on the effects of physical training

The effect of physical training on the natural history of varicocele has received little attention. The aim of the present pilot study was to evaluate the prevalence of idiopathic varicocele in young athletes, in the attempt to find a correlation between the training workload and the clinical grade of varicocele. We evaluated 150 adolescents with an age of 10-16 yr (median age: 13 yr). All these subjects were athletes practicing different sport at agonistic level. One hundred and fifty non-athlete adolescents of matched age (median: 13.5 yr) were used as controls. All underwent physical examination, and if a varicocele was suspected, the diagnosis was confirmed or excluded by echo-color-Doppler examination. The young athletes were stratified into two groups according to the different time spent for training: Group 1-6 h training per week; Group 2-7 to 12 h per week. Statistical analysis was performed. A p<0.05 was considered significant. The physical examination revealed a clinical varicocele on the left side in 20 athletes. A significant positive correlation was observed between the Group 2 and the highest grade of varicocele (r2=0.9918, p=0.0041). In the adolescent group used as control we observed a varicocele in 16 cases. A positive correlation was observed between the number of athletes with varicocele and the highest grade of varicocele (r2=0.96, p=0.02). Sport training does not modify the prevalence of varicocele compared to the general population, but physical activity has to be considered as an aggravating factor in the natural history of varicocele. In countries where sport eligibility is necessary for agonistic sport practice, varicocele should be then considered as a conditioning factor.

Dehydroepiandrosterone reduces expression and activity of BACE in NT2 neurons exposed to oxidative stress

Recently, we showed that oxidative stress activates the expression and activity of the beta-site AbetaPP-cleaving enzyme (BACE), an aspartyl protease responsible for the beta-secretase cleavage of AbetaPP. The identification of compounds able to prevent the induction of this event is an important goal of therapeutic strategies for Alzheimer's disease (AD). Dehydroepiandrosterone (DHEA) is an adrenal steroid that improves a variety of functions in the central nervous system. Moreover, a series of evidence suggests that DHEA displays antioxidant properties in different experimental models. In the present paper we show that pretreatment with DHEA is able to rescue the increase of mRNA expression, protein levels, and activity of BACE, produced by oxidative stress in NT2 neurons. BACE, being the enzyme that initiates the production of Abeta, is a drug target for AD. Our results imply that DHEA administration may slow down the AD pathological process, lowering Abeta accumulation.

Ultrasonic backscatter of the carotid wall in young and older athletes

OBJECTIVES

The aim of this study was to evaluate the effects of habitual exercise on the age-related changes of carotid wall composition defining its acoustic reflectivity by the quantitative approach of integrated backscatter (IBS) analysis.

DESIGN

Cross-sectional study.

SETTING

University Hospital.

SUBJECTS

Fifty-four competitive long-distance runners (males, age range 22-72 years) and 50 healthy sedentary controls.

MAIN OUTCOME MEASURES

All the subjects underwent both 2-D conventional ultrasonography and IBS analysis. IBS values were sampled from a region of interest (ROI) placed within five consecutive regions of the common carotid intima-media, and then corrected (C-IBS) for the IBS value of the adventitia.

RESULTS

Athletes showed a lower C-IBS (-27.07 +/- 2.9 dB vs. -24.57 +/- 4 dB, P < 0.0001) and a smaller intima-media thickness (IMT: 0.64 +/- 0.16 mm vs. 0.78 +/- 0.21 mm, P < 0.001) respect to sedentary controls. By selecting the lowest (<30 years of age) and the highest (>60 years of age) tertile of age, we assess the influence of age on IMT and IBS. Sedentary older individuals exhibited an IMT higher respect to young controls and to the both trained subgroups (P < 0.0001). C-IBS was lower in both subgroups of athletes, independently of age, and lower in sedentary young people respect to sedentary older subgroup (P < 0.0001). Endurance chronic exercise blunted the difference of C-IBS observed between young and older sedentary individuals. Moreover, C-IBS was positively related to age (r = 0.77, P < 0.0001) and IMT (r = 0.52, P < 0.0001).

CONCLUSIONS

The age-related changes of the arterial wall are attenuated by physical training. These modifications can be quantitatively discriminated by ultrasonic backscatter method.

Substance use among high-school students: relationships with temperament, personality traits, and parental care perception

Alcohol use, "alcohol abuse," and illicit drug use were investigated in a representative sample of 1076 urban, northern Italian high school students aged 14 to 19 years in 2001. In addition to questions on substance use, the participants were asked about school achievements and perceived substance use among friends. All the students were submitted to Zuckerman Sensation Seeking Scale (SSS) scale, Eysenck Personality Questionnaire (EPQ), Buss-Durkee Hostility Inventory (BDHI), and Parental Bonding Instrument (PBI). Lifetime alcohol use was found in 80.5%, "alcohol abuse" in 37.7%, cannabis use in 26.2%, ecstasy in 2.8%, heroin in 3.8%, and cocaine in 8.3% of the students: gender differences were significant for alcohol use, "alcohol abuse" and ecstasy use, with male subjects outnumbering females, but not for reported cannabis, heroin, and cocaine use. Early substance use onset among adolescents aged 14-16 years was detected. Higher sensation seeking on SSS, social coping impairment on EPQ, direct aggressiveness on BDHI, poor school achievements, and lower parental care on PBI were found associated with illicit drug use and "alcohol abuse" (multiple drugs users). Increased levels of aggressiveness and sensation seeking were evidenced both in minimal experimenters (ME) and habitual users (HU), without any significant difference, in comparison with abstinent students. Similarly, ME scored higher than abstinent subjects on EPQ for social coping impairment, but lower than HU. Parental care perception was lower in HU, but not in ME with, respect to abstinent subjects. Pearson inverse correlation was demonstrated between PBI scores and EPQ maladaptation and BDHI aggressiveness. Data from this preliminary pilot study suggest that temperamental traits and personality changes may be associated to early substance use "proneness" and reduced perception of parental care.

Ultrasonic tissue characterization of the myocardium in anorexia nervosa

AIM

To determine the systodiastolic variations in the integrated backscatter (IBS) signal of the myocardium in patients with anorexia nervosa.

METHODS

25 young women (aged 22.4 +/- 4.3 y) with overt anorexia nervosa, compared with 25 age-matched thin and 25 age-matched control women with body mass index >20 kg m(-2), underwent either conventional two-dimensional echocardiography or analysis of IBS cyclic variations.

RESULTS

Compared with thin and control subjects, anorectic patients showed reduced left ventricular mass (LVM: 82.9 +/- 17.1 vs 119.9 +/- 13.8 and vs 126.12 +/- 16.4 g, p < 0.0001; LVM indexed 21.4 +/- 3.3 vs 29.4 +/- 2.5 and vs 31.2 +/- 3.1 g m(-2.7), p < 0.0001), and IBS cyclic variations (septum: -0.49 +/- 2.18 vs 6.86 +/- 1.3 and vs 6.61 +/- 1.74 dB p < 0.0001; posterior wall: 2.77 +/- 2.12 vs 7.15 +/- 2.12 and vs 7.48 +/- 2.23 dB, p < 0.01).

CONCLUSION

Anorexia nervosa is associated with a significant reduction in the cyclic variation in IBS, which is also related to left ventricular hypotrophy. Ultrasonic tissue characterization could give an objective approach for the detection of myocardial structural properties and represent a preclinical index of myocardial dysfunction in anorexia nervosa.

Sarcoglycans in human skeletal muscle and human cardiac muscle: a confocal laser scanning microscope study

Sarcoglycans are a subcomplex of transmembrane proteins which are part of the dystrophin-glycoprotein complex. They are expressed in the skeletal, cardiac and smooth muscle. Although numerous studies have been conducted on the sarcoglycan subcomplex in skeletal and cardiac muscle, the manner of the distribution and localization of these proteins along the nonjunctional sarcolemma is not clear. We therefore carried out an indirect immunofluorescence study on surgical biopsies of normal human skeletal muscle and of healthy human atrial myocardium biopsies of patients affected by valvulopathy. Our results indicate that, in skeletal muscle, sarcoglycans have a costameric distribution and all colocalize with each other. Only in a few cases did the alpha-sarcoglycan not colocalize with other sarcoglycans. In addition, these glycoproteins can be localized in different fibers either in the regions of the sarcolemma over band I or band A. In cardiac muscle, our results show a costameric distribution of all proteins examined and, unlike in skeletal muscle, they show a constant colocalization of all sarcoglycans with each other, along with a consistent localization of these proteins in the region of the sarcolemma over band I. In our opinion, this situation seems to confirm the hypothesis of a correlation between the region of the sarcolemma occupied by costameric proteins and the metabolic type, fast or slow, of the muscular fibers. These data, besides opening a new line of research in understanding interactions between the sarcoglycans and other transmembrane proteins, could also be extended to skeletal and cardiac muscles affected by neuromuscular and cardiovascular pathologies to understand possible structural alterations.

Anomalous origin of the circumflex artery and patent foramen ovale: a rare cause of myocardial ischaemia after percutaneous closure of the defect

A 35 year old man with a history of transient ischaemic attack and atrial septal aneurysm underwent percutaneous closure of a patent foramen ovale (PFO) with a transcatheter device. After the procedure the patient developed effort angina not present previously. Transoesophageal echocardiography confirmed the absence of residual shunt but showed an abnormal linear image running behind the aortic root. Magnetic resonance imaging detected an anomalous origin of the circumflex coronary artery from the right coronary sinus. The anomalous artery was located between the aortic root and the PFO closing device, causing coronary insufficiency. This report describes a rare complication of transcatheter PFO closure.

QT dispersion in elderly athletes with left ventricular hypertrophy

The purpose of this study was to examine the QT dispersion in elderly endurance athletes with left ventricular (LV) hypertrophy. Sixteen athletes (males, mean age 67.6 +/- 4.5 years) with mild to moderate LV hypertrophy, were compared with 16 age-matched hypertensive patients with similar degree of LV hypertrophy and 16 age-matched healthy sedentary controls. All the participants underwent echocardiogram and 12-lead electrocardiogram. QT dispersion was defined as the difference between maximum and minimum QT intervals in the different leads. QT dispersion was corrected (QTc) for heart rate according to Bazett's formula. The results showed in athletes and hypertensive patients comparable LV mass (258.2 +/- 14.2 vs. 262.4 +/- 16.8 g, ns), which was significantly higher than that of controls (p < 0.001). Trained subjects had QT dispersion (38.6 +/- 10.2 ms) and QTc dispersion (39.4 +/- 11.3 ms) significantly lower than hypertensive patients (QT dispersion: 68.4 +/- 11.4 ms; QTc dispersion: 72.2 +/- 8.4, p < 0.001) and comparable with controls (QT dispersion: 44.3 +/- 8.4 ms; QTc dispersion: 46.2 +/- 6.2 ms, ns). In conclusion, in elderly athletes training-induced myocardial hypertrophy was characterized by a QT dispersion significantly lower than hypertensive myocardial hypertrophy. This could provide a simple and inexpensive screening method for differentiating physiologic from pathologic myocardial hypertrophy in elderly subjects.

Actin-associated proteins in ameloblast differentiation

Focal contacts are systems of adherens junctions of the cell-extracellular matrix type, which allow the transfer of fundamental signals from the extracellular matrix to nuclear compartments, capable of regulating adhesion, proliferation, migration and differentiation of cells. Recently, many authors have concentrated their attention on epitheliomesenchymal interactions which guide organogenesis of dental germ, identifying numerous growth and differentiation factors and having the inner enamel epithelial cells of the enamel organ as a target. Given that the two cellular compartments in their tooth germ are separated by a basal membrane and by an extracellular matrix, which touches it, we wanted to evaluate the presence of focal contacts through the identification of talin and vinculin, proteins of the actin-associated protein complex. In this study we utilized the hemimandibles of young Wistar rats and we extracted the related odontogenic tooth organs present at their apical end. Specimens are processed with antibody against vinculin and talin. Results show that these junctional system proteins are present at the apical poles of both cellular compartments suggesting that putative epithelial-mesenchymal interactions, other than marker molecules, may use focal contacts as a system for transmission of signals.

Hysteroscopic findings in postmenopausal abnormal uterine bleeding: a comparison between HRT users and non-users

OBJECTIVES

The aim of our study was to investigate hysteroscopic findings in a sample of 410 menopausal women (hormonal replacement therapy, HRT users n = 219 and HRT non-users n = 191) and to evaluate the relationship between the presence of intrauterine disease, the use of HRT and the presence of AUB.

METHODS

Two hundred and nineteen women on HRT underwent standard office hysteroscopy by means of the Hamou hysteroscope (in 94 cases for abnormal uterine bleeding (AUB) and in 125 cases for periodic endometrium monitoring). One hundred and ninety-one women who had never received HRT were submitted to office hysteroscopy (154 for AUB and 37 for other reasons).

RESULTS

Intrauterine diseases are more frequent in patients who do not use HRT (P = 0.02). Endometrial polyps is a frequent disease present in 30% of the sample (23.7% of HRT users and 30.8% of HRT non-users). Myomas were present in 8.7% of all patients examined (6.8% of HRT users and 11% of HRT non-users). Irregular bleeding in menopause is often associated with endouterine abnormalities: in symptomatic patients the frequency of endouterine diseases was 41% while in asymptomatic patients was 28% (P = 0.003). In patients taking HRT (n = 219) endouterine disease is demonstrated in 37% with AUB and in 26% without AUB (P = 0.07).

CONCLUSION

Benign intrauterine diseases (endometrial polyps and submucous myomas) are more frequent in postmenopausal women who do not use HRT. In patients taking HRT irregular bleeding is associated with intrauterine diseases; however, the absence of AUB does not exclude the presence of endometrial polyps or myomas.

[Regional anesthesia in quadrantectomy and sentinel lymph node]

After a brief mention about the mammary surgery, the Authors discuss the availability of regional anesthesia for quadrantectomy and "sentinel" node or axillary dissection.

[Ultrasonographic and biochemical screening of adnexal masses before operative laparoscopy]

BACKGROUND

The object of our study was to evaluate how reliable ultrasonographic and biochemical screening of adnexal masses are in the selection of patients eligible for operative laparoscopy.

METHODS

The study was performed at the First Clinic of Obstetrics and Gynecology, University of Rome La Sapienza, Italy. Eighty-seven women of 36.8 +/- 12 years of age, who underwent operative laparoscopy between January 1999 and January 2000 to remove an adnexal lesion, were enrolled. These adnexal lesions had been previously diagnosed on the basis of a pelvic ultrasonographic imaging; this was performed because of follow-up procedure or pelvic pain. The lesions were evaluated preoperatively according to Sassone echographic scoring system. The CA-125 level was determined in 58 patients.

RESULTS

Surgery was successful in all 87 cases. In one case the operative laparoscopy had to be turned into laparotomy since the histologic examination revealed an atypical proliferative mucinous cystoadenoma. Sassone total average echographic score was 6.0 +/- 1.7; this is below the discriminant cut-off for malignancy (9). The only case in which Sassone score reached 10 was an atypical cystoadenoma. The CA-125 level was higher than 35 IU/ml (cut-off of this marker) in 13.7% of the patients; these were all affected by endometriosis or had a hemorrhagic corpus luteum. In the patient with atypical cystoadenoma, the CA-125 level was within normal range (29.1 UI/ml). The post-operative period was uneventful in all cases but one, in which the occurrence of pulmonary thromboembolism required a prolonged hospitalization.

CONCLUSIONS

The use of Sassone echographic scoring system proved to be very useful and effective in the selection of the patients. Tumor markers are relevant factors only if their evaluation is accompanied by an accurate anamnesis and is supported by the findings of abdominal and transvaginal ultrasonography.

Nitric oxide synthase patterns in normal and varicocele testis in adolescents

OBJECTIVE

To determine if the testes of normal adolescents can produce nitric oxide (NO), by assessing NO synthase (NOS) activity, and whether this activity changes in adolescents with left idiopathic varicocele.

PATIENTS AND METHODS

After obtaining informed consent, testicular biopsies were obtained from eight adolescents (mean age 16.4 years; controls) who underwent surgery for inguinal hernia or hydrocele, and from 20 adolescents (mean age 16.2 years) operated for left idiopathic varicocele. Inducible and endothelial NOS (iNOS and eNOS) isoforms were investigated in the biopsy specimens by immunohistochemical localization and Western blot analysis using specific fluorescein-conjugated antibodies.

RESULTS

Both normal and pathological samples expressed eNOS at the level of vessels and Leydig cells. The iNOS was expressed in Leydig cells of normal testes and over-expressed in Leydig cells of varicocele testes.

CONCLUSION

Leydig cells of adolescent testes constitutively express iNOS. Under pathological conditions, e.g. varicocele, iNOS is up-regulated and is a possible source of NO overproduction. These results could be useful in explaining the pathogenesis of both testis and sperm dysfunction in varicocele.

Normal and varicocele testis in adolescents

The authors reviewed the results of their research on the structure and composition of normal and varicocele seminiferous tubules in adolescents. They give new evidences of normal structure of adolescent testis and demonstrate, for the first time, the ultrastructural and immunohistochemical modifications of the lamina propria and basal lamina in the adolescent varicocele patients, which are similar to those observed in adults, but less severe, and of the adherence junctions in seminiferous tubules. They also report the presence of oxidative stress in adolescents limited to testis and not generalised as in the adults. These data are well correlated to different clinical studies that support the hypothesis of a progressive course of varicocele and the need for surgical treatment in adolescent varicocele patients.

Left ventricular outflow tract obstruction in the transposition of great arteries defined by transthoracic three-dimensional echocardiography

We assessed the feasibility of transthoracic three-dimensional reconstruction of the pulmonary valve and subpulmonary left ventricular outflow tract in two patients with transposition of great arteries, ventricular septal defect, and obstruction to the left ventricular outflow tract. Three-dimensional reconstruction of the pulmonary valve could be displayed as "en face" through a three-dimensional generated "pulmotomy view," allowing an overview of the pulmonary aspect of the valve from a surgeon's perspective. In similar fashion, reconstruction of the subpulmonary outflow tract could be displayed along its longitudinal axis as seen through a left ventriculotomy. Unique views could be obtained equivalent to surgical or autopsy dissections, allowing more complete understanding of the morphology and severity of left-sided obstructive lesions.

Surface states and negative electron affinity in polyethylene

First-principles calculations are used to investigate the electronic properties of the surfaces of polyethylene. The calculations support the experimental evidence of a negative electron affinity, with calculated values of -0.17 eV and -0.10 eV for surfaces with chains perpendicular and parallel to the surface normal, respectively. Both surfaces exhibit a surface state with binding energy -1.2 +/- 0.5 eV with respect to the bulk polyethylene conduction band minimum. Implications of these findings on spectroscopy, as well as on the transport and aging properties of polyethylene for high-voltage applications, are discussed.

The 6-F nitinol TrapEase inferior vena cava filter: results of a prospective multicenter trial

PURPOSE

The authors report the first results of a new 6-F symmetrically designed permanent nitinol inferior vena cava (IVC) filter, the Cordis TrapEase, evaluated in a multicenter prospective study with 6-months of follow-up.

MATERIALS AND METHODS

A total of 65 patients (29 men, 36 women) who ranged in age from 37 to 96 years (mean age, 68 years) and who were at high risk of pulmonary embolism (PE) were enrolled in 12 centers in Europe and Canada. The study was approved by the institutional review boards at all centers. Study objectives were to evaluate filter effectiveness, filter stability, and caval occlusion. Indications for filter placement were deep vein thrombosis with recurrent thromboembolism and/or free-floating thrombus with contraindication to anticoagulation in 37 patients, and complications in achieving adequate anticoagulation in 28 patients. Follow-up included clinical examination, plain film, Doppler ultrasound, CT scan, and nuclear medicine.

RESULTS

The analysis of the data revealed a technical success of 95.4% (three filter-system related implantations not at the intended site, no events of filter tilting) and a clinical success of 100% at 6 months (no cases of symptomatic PE), the study primary endpoint. There were no cases (0%) of filter migration, insertion site thrombosis, filter fracture, or vessel wall perforation. During the study period, there were two cases of filter thrombosis: one case of early symptomatic thrombosis that was successfully treated in the hospital, and one case of nonsymptomatic filter thrombosis detected at 1-month follow-up, with spontaneous recanalization at 3 months. In the latter patient, some residual thrombus was still detected at 6 months. Of the study population of 65 patients, there were 23 deaths. These deaths were not related to the device or the implantation procedure but to the underlying disease process.

CONCLUSION

This study demonstrates the new nitinol permanent IVC filter to be a safe and an effective device, with a low overall complication rate, for use in patients with thromboembolic disease at high risk of PE.

Nitric oxide production is increased in the spermatic veins of adolescents with left idiophatic varicocele

BACKGROUND/PURPOSE

The existence of an excessive release of nitric oxide (NO) within dilated spermatic veins has been recorded in adults with varicocele suggesting a high oxidative stress. The authors investigated whether NO overproduction is already present in the dilated veins of adolescent varicocele and which enzymatic isoforms in the spermatic vein could be expressed.

METHODS

The study group consisted of 10 adolescent patients affected by left idiophatic varicocele of grade II and III. The increase in NO production was established by determination of serum concentration of L-hydroxyarginine (L-NHA) and Nitrite/nitrate (NOx). Both endothelial and inducible NOsynthase (NOS) were investigated by Western blot analysis and by immunohistochemical localization using specific monoclonal fluorescein conjugated antibodies.

RESULTS

Serum L-NHA levels were significantly greater in the spermatic veins when compared with the peripheral veins 176.8 +/- 32.3 micromol/L versus 3.38 +/- 0.64 micromol/L (P =.0004 Similarly, NOx levels were increased, respectively, 68.2 +/- 16.7 nmol/mL versus 12.9 +/- 2.65 nmol/mL (P =.029). Endothelial NOS was localized in the spermatic vein of varicocele patients, but not overexpressed; the inducible isoform was not detected.

CONCLUSIONS

Adolescents with varicocele already present an increase in NO within dilated veins. The dilated spermatic vein is not the major source for the increase in NO level. These results could have an implication in the natural history of adolescent varicocele and in programming the ideal time for surgical treatment.

New insights in the pathophysiology of mitral and aortic regurgitation in pediatric age: role of angiotensin-converting enzyme inhibitor therapy

This review has been focused on the new insights in the pathophysiology of mitral and aortic regurgitation and on the role of ACE-inhibitor therapy in children with chronic volume overload due to left-sided valvular lesions. Recent clinical studies show that these drugs have favorable effects when administered orally in chronic mitral and aortic regurgitation. Interestingly, the beneficial effects of ACE-inhibition regard the basic anatomic, hemodynamic and adaptive pathologic conditions related to volume overload, namely, the regurgitant orifice area and volume and ventricular remodeling. The heart is a plastic structure, constantly being altered in size, shape and composition in response to chronic volume overload. Thus, modulation of cardiac plasticity by ACE-inhibition raises the possibility of using new therapeutic strategies specifically designed to prevent and/or antagonize the mechanical disadvantages secondary to volume overload-induced cardiac remodeling. The beneficial effects of ACE-inhibition have also been observed in growing children with asymptomatic valvular regurgitation; thus, it appears that the unloading therapy has the potential of influencing the natural history of both mitral and aortic regurgitation and possibly delays surgical valve repair or replacement. These data justify early inhibition of the renin-angiotensin system in children with left ventricular volume overload due to mitral and aortic regurgitation.