Exo-Ocean Exploration with Deep-Sea Sensor and Platform Technologies.

One of Saturn's largest moons, Enceladus, possesses a vast extraterrestrial ocean (i.e., exo-ocean) that is increasingly becoming the hotspot of future research initiatives dedicated to the exploration of putative life. Here, a new bio-exploration concept design for Enceladus' exo-ocean is proposed, focusing on the potential presence of organisms across a wide range of sizes (i.e., from uni- to multicellular and animal-like), according to state-of-the-art sensor and robotic platform technologies used in terrestrial deep-sea research. In particular, we focus on combined direct and indirect life-detection capabilities, based on optoacoustic imaging and passive acoustics, as well as molecular approaches. Such biologically oriented sampling can be accompanied by concomitant geochemical and oceanographic measurements to provide data relevant to exo-ocean exploration and understanding. Finally, we describe how this multidisciplinary monitoring approach is currently enabled in terrestrial oceans through cabled (fixed) observatories and their related mobile multiparametric platforms (i.e., Autonomous Underwater and Remotely Operated Vehicles, as well as crawlers, rovers, and biomimetic robots) and how their modified design can be used for exo-ocean exploration.

Complete genome sequence of Neisseria meningitidis serogroup B strain MC58.

The 2,272,351-base pair genome of Neisseria meningitidis strain MC58 (serogroup B), a causative agent of meningitis and septicemia, contains 2158 predicted coding regions, 1158 (53.7%) of which were assigned a biological role. Three major islands of horizontal DNA transfer were identified; two of these contain genes encoding proteins involved in pathogenicity, and the third island contains coding sequences only for hypothetical proteins. Insights into the commensal and virulence behavior of N. meningitidis can be gleaned from the genome, in which sequences for structural proteins of the pilus are clustered and several coding regions unique to serogroup B capsular polysaccharide synthesis can be identified. Finally, N. meningitidis contains more genes that undergo phase variation than any pathogen studied to date, a mechanism that controls their expression and contributes to the evasion of the host immune system.

Blood pressure estimation in the human fetal descending aorta.

OBJECTIVES: The objectives of this study were to estimate fetal blood pressure non-invasively from two-dimensional color Doppler-derived aortic blood flow and diameter waveforms, and to compare the results with invasively derived human fetal blood pressures available from the literature. METHODS: Aortic pressures were calculated from digitally recorded color Doppler cineloops of the fetal descending aorta by applying the Womersley model in combination with the two-element Windkessel model, assuming constant pulse wave velocity during the second half of pregnancy. The results were compared with invasively derived human fetal blood pressures obtained from the literature. RESULTS: In 21 normal pregnancies the estimated mean aortic pressure regression line increased linearly from 28 mmHg at 20 weeks of gestation to 45 mmHg at 40 weeks of gestation. The pulse pressure based on the regression line increased linearly from 21 mmHg at 20 weeks of gestation to 29 mmHg at 40 weeks of gestation. The aortic compliance exhibited a log linear relationship with the gestational age and a statistically significant eightfold increase was observed between 20 and 40 weeks. The aortic downstream peripheral resistance exhibited an exponentially decaying relationship across the same gestational age range. Non-invasively derived aortic systolic and diastolic aortic pressures were comparable with previously reported invasively derived systolic and diastolic umbilical arterial pressures; however, the mean pressures differed significantly from those reported in the umbilical artery in a separate study. The aortic systolic pressures calculated in this study were significantly higher than invasively derived left ventricular systolic pressures that have been previously reported in the literature. CONCLUSIONS: This study demonstrates the feasibility of estimating arterial blood pressure in the human fetus. The method described is of potential use in assessing fetal blood pressure non-invasively, particularly for studying relative changes with time.

Corrected QT interval prolongation in anthracycline-treated survivors of childhood cancer.

PURPOSE: Comprehensive cardiac evaluations are currently recommended for all anthracycline-treated patients to detect subclinical cardiac failure. A screening test is needed that would easily and inexpensively identify patients who are at risk for late cardiac decompensation. METHODS: We routinely reviewed the ECG and echocardiogram (ECHO) results of 52 of 56 anthracycline-treated long-term survivors of childhood cancer who had received > or = 100 mg/m2 of ANTH (ANTH = 1 mg/m2 of doxorubicin), and who were not in clinical heart failure. Exercise testing was performed in eight patients with a corrected QT interval (QTc) of > or = 0.43. RESULTS: Zero of 15 patients (without chest radiation) who received less than 300 mg/m2 of ANTH versus six of 22 who received > or = 300 mg/m2 of ANTH had a QTc > or = 0.43 (P = .03). Three of 15 patients (with chest radiation) who received less than 300 mg/m2 of ANTH versus 12 of 22 who received > or = 300 mg/m2 of ANTH had a QTc > or = 0.43 (P = .03). For all patients (including those with chest radiotherapy), zero of 19 who received less than 300 mg/m2 of ANTH versus eight of 33 who received > or = 300 mg/m2 of ANTH had a QTc of > or = 0.45 (P = .025). Three of 19 who received less than 300 mg/m2 of ANTH versus 19 of 33 who received > or = 300 mg/m2 of ANTH had a QTc of > or = 0.43 (P = .003). One patient had decreased fractional shortening (FS) and QTc prolongation. Cardiac decompensation (with a FS of 24%) occurred with propranolol in a patient with previously normal FS but prolonged QTc. With exercise, the QTc became further prolonged in all four patients with a QTc of 0.44 to 0.46 and in two of four patients with a QTc of 0.43. CONCLUSION: Prolongation of the QTc, a measure of myocardial repolarization, may reflect injury to myocardial cells. QTc prolongation may be predictive of an increased risk of late cardiac decompensation. If the utility of the QTc measure is confirmed, screening for evidence of myocardial damage can be easily and inexpensively performed by oncologists and primary caretakers.

Distribution of blood flow between embryo and vitelline bed in the stage 18, 21 and 24 chick embryo.

OBJECTIVE: We defined the distribution of blood flow between the embryo and the extraembryonic vascular bed as an initial step in understanding the control of flow distribution in the early developing heart. METHODS: Dorsal aortic blood flow of stage 18, 21, and 24 chick embryo (n > or = 7 at each stage) was measured with a 20 MHz pulsed-Doppler velocity meter. Analog waveforms were digitally sampled at 500 Hz. 1-5 x 10(3) yellow microspheres in saline suspension were injected into the vitelline vein. The embryo and the extraembryonic vascular bed were harvested and separated from each other. The dye on the microspheres from each portion was extracted and extrapolated from the standard curve of the absorbance of dye concentrations per number of microspheres quantified by spectrophotometry. Blood flow was calculated from the integral of blood velocity and aortic cross-sectional area multiplied by the fraction distribution of microspheres in the embryo and extraembryonic vascular bed. Data were presented as mean +/- standard error of the mean. RESULTS: The proportion distribution of microspheres between embryo and extraembryonic vascular bed shifted from 18.7 +/- 2.5 vs. 81.3 +/- 2.5% at stage 18, 25.1 +/- 3.0 vs. 74.9 +/- 3.0% at stage 21, and 34.2 +/- 2.4 vs. 65.8 +/- 2.4% at stage 24. Indices of blood flow normalized to wet weight (mean +/- 95% confidence interval) were similar between the embryo and the extraembryonic vascular bed, but increased throughout the stages. CONCLUSION: During embryogenesis, blood flow per unit mass is evenly distributed between the metabolically active embryo and the extraembryonic vascular bed.

Rate of coronary vascularization during embryonic chicken development is influenced by the rate of myocardial growth.

OBJECTIVE: We tested the hypothesis that the degree of coronary microvessel formation in the embryonic heart is regulated by the magnitude of myocardial growth. METHODS: The outflow tract of Hamburger-Hamilton stage 21 chicken hearts (prior to the onset of coronary vasculogenesis) was constricted in ovo with a loop of 10-0-nylon suture, and the hearts were studied at stages 29 and 36. RESULTS: At stage 29 ventricular mass was 64% greater in the pressure-overloaded than in the hearts of sham-operated controls, but vascular volume density and numerical density, determined by electron microscopic morphometry, were identical. As demonstrated by histological morphometric evaluation, the compact region of the left ventricle at stage 29 was 43% thicker than the shams. However, by stage 36 heart mass, thickness of the compact region, and overall wall thickness (demonstrated by scanning electron microscopy) were significantly less than in the sham group of this stage, but vascular volume density was virtually identical in the two groups. Formation of the two main coronary arteries was clearly impeded in the banded hearts, i.e., the coronaries were stunted in their development or failed to completely form coronary ostia. CONCLUSIONS: Vascular growth is proportional to myocardial growth in the embryonic, overloaded heart, but the persistence of the pressure overload results in a failure of or severe limitations in coronary artery development. These data support the hypothesis that vascular growth during this period of development is regulated, at least in part, by the rate and magnitude of myocardial growth.

An estimate of fetal autonomic state by spectral analysis of human umbilical artery flow velocity waveforms.

OBJECTIVE: Determination of gestational age-related fluctuations in heart rate in the umbilical artery of the early human fetus. METHODS: Doppler velocity recordings from human umbilical artery were obtained, in a cross-sectional study design in 137 singleton pregnancies at 10-20 weeks of gestation. After exclusion criteria were applied, data on 117 normal pregnancies were available and subdivided into group I: 10-12 weeks (n = 49); group II: 13-16 weeks (n = 43); and group III: 17-20 weeks (n = 25). Blood flow velocity waveforms were reconstructed from Doppler audio signals. Variability in heart rate was calculated using Fast Fourier Transforms (FFT). Individual heart rate variability power spectra were subdivided into frequency bands. RESULTS: Fetal heart rate variability decreases at 10-20 weeks and demonstrates a shift to lower frequencies at 17-20 weeks. CONCLUSIONS: Fetal heart rate variability is related to gestational age and shows a shift to lower frequencies which may reflect autonomic functional development.

Effect of conotruncal constriction on aortic-mitral valve continuity in the stage 18, 21 and 24 chick embryo.

The effect of conotruncal constriction on the development of aortic-mitral valve continuity in stage 18, 21 and 24 chick embryos was studied. A 10-0 nylon suture was tied around the conotruncus, constricting the outflow tract of the heart. The loop was removed after 4 or 24 hours or left permanently in place in 3 subgroups of the 236 experimental embryos. The embryo hearts were harvested at stages after completion of cardiac morphogenesis, fixed in end-diastole and microdissected. The distance between the mitral and aortic anuli was measured from the base of the heart with a calibrated filar micrometer eyepiece. This measurement was compared with the mitral-aortic separation in 72 normal and 132 control embryos. The mitral-aortic separation was similar among normal, control and 4- and 24-hour experimental embryo hearts. However, the mitral-aortic separation increased from 0.34 +/- 0.02 mm in normal hearts to 0.82 +/- 0.25 mm in stage 18, 1.11 +/- 0.36 mm in stage 21 and 0.75 +/- 0.33 mm in stage 24 permanent loop experimental hearts (p less than 0.01). In embryo hearts with an increased mitral-aortic separation, both great vessels arose from the right ventricle, the semilunar valves were at the same level and the ventricular septal defect was present beneath the aortic anulus. We conclude that conotruncal constriction modifies the relation of the aortic and the mitral valve. We speculate that conotruncal constriction alters the migration of mesenchymal tissue into the heart.

Atrial defect size after Blalock-Hanlon atrioseptectomy.

In transposition of the great arteries, a Blalock-Hanlon closed atrial septectomy is performed to improve intracardiac mixing at the atrial level. Although the Blalock-Hanlon septectomy is a common surgical procedure in cyanotic congenital heart disease, it has not been adequately assessed pathologically. In 14 heart specimens from patients (aged 3 days to 19 years) with transposition of the great arteries and Blalock-Hanlon septectomy, the margins of the septectomy, fossa ovalis and atrial septum were identified. The total area of the septum and its defects was calculated using planimetry. The ratio of defect size to atrial septal area was expressed as percent communication, which ranged from 5 to 39 (mean 18) percent in eight specimens with intact limbus of the foramen ovale and 26 to 57 (mean 42) percent in six specimens in which the limbus had been excised. The finding that specimens in which the Blalock-Hanlon defect extended into the fossa ovalis had the largest total communication emphasizes that to obtain optimal bidirectional atrial mixing the surgeon should extend the Blalock-Hanlon procedure across the limbus into the foramen ovale.

Critical aortic coarctation: patch aortoplasty in infants less than age 3 months.

Twenty-three infants less than age 3 months (mean age 31 days) underwent patch aortoplasty for relief of coarctation of the aorta. All had intractable congestive heart failure, despite aggressive medical therapy. Each infant had other cardiac anomalies, including patent ductus arteriosus (83 percent) and ventricular septal defect (74 percent). All patients underwent closure of the ductus arteriosus and patch angioplasty of the aorta to produce a luminal diameter of at least 16 mm. In addition, 9 of the 17 patients (53 percent) with a large shunt ventricular septal defect underwent pulmonary arterial banding. There was one hospital death 42 days after operation secondary to bowel perforation and sepsis. Hospitalization beyond 21 days postoperatively was always due to other unrepaired cardiac lesions. The three late deaths at 3, 9 and 18 months after operation were associated with additional major anomalies. Fourteen patients have had postoperative catheterization. No gradient was found across the site of coarctation repair, but one patient had a gradient between the left carotid and left subclavian arteries. Surgical repair of critical coarctation of the aorta in infants can safely be offered despite the presence of other cardiac anomalies.

Familial risks of congenital heart defect assessed in a population-based epidemiologic study.

Congenital heart defects (CHD) represent a heterogeneous group of disorders caused by chromosome abnormalities, mendelian disorders, teratogenic exposures, and unknown etiologic mechanisms. A large group of various isolated defects is presumably multifactorial in origin. Previous studies of familial risks for specific anatomic defects obtained from clinical series may include significant biases and obscured pathogenic relationships. In this population-based study we analyzed all cases of CHD in infants and a control birth cohort in the Baltimore-Washington area. The rates of CHD were defined for first-degree relatives of cases with isolated defects, grouped by a pathogenic classification scheme. Precurrence risks were found to vary among the groups, and risks for flow lesions were higher than previously reported. The sibling precurrence risk for hypoplastic left heart syndrome (13.5%) was not significantly different from that expected for an autosomal recessive mechanism; the risks for different types of ventricular septal defects (VSD) varied among mechanistic groups. The results indicate that the additive multifactorial model does not adequately account for the risks in all forms of isolated CHD of unknown etiology.

Congenital aortic stenosis with hypoplasia of the left sinus of Valsalva. Anatomic reconstruction of the aortic root.

Evaluation of the aortic root in 13 patients with congenital aortic stenosis aged 2.5 to 24 years (mean 8.3 years) has revealed morphologic characteristics of asymmetry of the aortic root caused by a small (hypoplastic) left sinus of Valsalva associated with a supravalvular ridge above the left coronary ostium and dysplasia of the aortic valve. The asymmetry resulted in folding and buckling of the left aortic cusp. The aortic valve was classified as bicuspid in 11 of the 13 patients. Preoperative aortography was characteristic and revealed the diagnosis in all patients. The average left ventricle-aorta systolic pressure gradient was 81 mm Hg. Operative repair consisted of an oblique aortotomy extended in a spiral fashion to the right and posteriorly into the left sinus of Valsalva. Seven patients had further mobilization of the posterior commissure with a second incision to the right of the commissure into the noncoronary sinus. Slightly fused valve commissures were opened in 12 patients. Aortic root reconstruction was accomplished with a spiral Dacron patch and posterior commissural repositioning. Follow-up catheterization at 9 to 35 months (mean 24 months) in five patients demonstrated an average outflow tract systolic gradient of 28 mm Hg and a more symmetrical appearance of the aortic root.

Total anomalous pulmonary venous connection.

Total anomalous pulmonary venous connection (TAPVC) was repaired by operation in 20 infants during a 101/2-year period (1972 to 1983). Five patients died following operation. Factors that most affected mortality were the condition of the patient prior to repair, the year of operation, and the technique used for repair. Operative mortality before 1976 was significantly different from that after 1976 (57% [4/7] versus 8% [1/13], respectively; p less than 0.04). Prior to 1976, the several techniques used for anastomosis of the left atrium to the common pulmonary vein involved displacement of the heart from its anatomical position. After 1976, a standard approach using a right atriotomy for access was adopted for all such repairs. Intracardiac type of TAPVC was repaired by pericardial patch to direct blood flow through the atrial septal defect to the left atrium. Supracardiac and infracardiac types were repaired by enlarging the atrial septal defect so that a transverse incision through the back of the left atrium was exactly overlying the pulmonary vein posteriorly. A large anastomosis of the left atrium and common pulmonary vein was made with the heart in its natural anatomical position, which eliminates the possibility of distortion of the anastomosis. A pericardial patch was used to close the atrial septal defect. This experience suggests that the right transatrial approach of creating an anatomically correct anastomosis of the left atrium to the common pulmonary vein is an important factor in reducing operative mortality in patients with TAPVC.

Pulmonary stenosis in infants and young children.

Twenty-four patients less than 3 years old underwent operation for pulmonary stenosis. Pulmonary dysplasia was diagnosed preoperatively in only 4 patients; in 20 patients the lesion was categorized simply as pulmonary stenosis. At operation, more severe valve deformities were often present in patients less than 2 years of age. Preoperative evaluation did not reveal the extent of the deformity in 7 additional patients. The deformities included not only valvular dysplasia (thickened redundant valve cusps) but also supravalvular and annular abnormalities. Relief of obstruction was obtained only when all components of the obstructive abnormality were relieved. Patch angioplasty of the right ventricular outflow tract was necessary in 13 patients with complex morphology. Valvotomy was effective only for pulmonary stenosis due to pure commissural fusion. A spectrum of the morphology of pulmonary stenosis is recognized, with more complex lesions than simple commissural fusion identified in younger children. The more complex lesions may require more extensive operations (outflow tract patch) to completely relieve the obstructive pathological condition in the outflow tract.

Changing indications for pacemakers in children.

Permanent pacemakers were implanted in 50 children. Indications were symptomatic sinus node dysfunction in 34 (68%), surgical block in 9 (18%), and congenital block in 7 (14%). Twenty-three (68%) of the 34 children with sinus node dysfunction had undergone prior cardiac operations. Only 4 of the 50 patients (8%) had electrode problems after a mean pacing time of 29.5 months (range, 1 to 96 months). All 35 of the mercury-cell pulse generators used in 28 patients ceased to function after an average useful life of 20.8 months (range, 1 to 51 months). The lithium-powered units in the 45 survivors all show satisfactory pacing after 5 to 44 months (mean, 28.1 months). With improved pacemaker technology, longer survival after complex repairs, and better monitoring techniques, the indications for cardiac pacing in children have broadened. Surgical block now is an indication in only a small fraction of the pediatric pacemaker population. Sinus node dysfunction accounts for an ever-increasing majority of the pacemakers we currently implant in children.

Late complications following surgical repair of total anomalous pulmonary venous return below the diaphragm.

Between May, 1975, and June, 1977, we surgically repaired an infracardiac total anomalous pulmonary venous return in 4 infants under deep hypothermic cardiac arrest. All patients had pulmonary hypertension and a patent ductus arteriosus. All survived operation and required positive end-expiratory pressure with mechanical ventilation. Late complications included patent ductus arteriosus not visualized at initial catheterization, breakdown of an oversewn atrial septal defect repair, and pulmonary venous obstruction despite an anastomosis diamter of 1.5 to 2.5 cm. At reoperation, there was scarring and contraction at the junction of the pulmonary veins and left atrium. One infant with these complications died post-operatively. In another patient, there was kinking of the left lower pulmonary vein at its juncture with the left atrium. In view of these complications we currently recommend the following: ligation of the ductus arteriosus regardless of catheterization findings; a right-sided approach to avoid pulmonary vein kinking; prosthetic patch closure of the atrial septal defect to avoid excessive tension on suture lines and to maintain maximum left atrial size; stellate anastomosis to provide the largest possible drainage channel; awareness that an unusually high positive end-expiratory pressure may be required postoperatively; and early recatheterization.

Pathogenetic mechanisms of congenital cardiovascular malformations revisited.

Rapid advances in cardiovascular science have expanded our knowledge of the mechanisms of heart development. Epidemiologists have defined the prevalence of congenital cardiovascular malformations, developmental biologists have delineated cascades of cell lineage, and molecular geneticists have identified mutations and loci associated with familial heart and vascular defects. We are well on the way to a molecular understanding of congenital cardiovascular malformations. Thus, it seems appropriate to review the pathogenetic classification of congenital cardiovascular malformations in light of this new clinical and scientific evidence. This schema serves as a template for the scientist to organize clinical information relevant to the pathogenesis of cardiac defects and as a tool for the clinician in approaching the difficult task of counseling parents of children with congenital cardiovascular malformations.

Morphologic characteristics of aortic atresia: implications for fetal hemodynamics.

We studied hearts with aortic atresia to determine the relationship between cardiac morphology and fetal cardiac blood flow. We compared measurements of aortic, pulmonary, and tricuspid valve circumference and right ventricular wall thickness among 37 hearts with aortic atresia and mitral hypoplasia, 14 hearts with aortic atresia together with mitral atresia and 24 normal hearts. Right ventricular free wall thickness and tricuspid and pulmonary valve annular circumferences were greater and aortic circumferences were smaller in hearts with aortic atresia than in normal hearts (P less than 0.05). Between the subgroups of aortic atresia, the aortic circumference was 5 +/- 1 mm in those with mitral atresia compared to 7 +/- 2 mm in association with mitral hypoplasia (P less than 0.05). The morphologic differences between the subgroups of aortic atresia are consistent with differences in fetal blood flow. Left heart blood flow was likely to be greater during development in those hearts with aortic atresia and mitral hypoplasia than in those with the combination of aortic and mitral atresia.

Abnormalities in position of left ventricular papillary muscles in congenital aortic stenosis.

Subclinical structural abnormalities may accompany some congenital cardiovascular abnormalities. Echocardiographic observations led us to hypothesize that the positions of the left ventricular papillary muscles are abnormal in hearts with aortic valvar stenosis. To test this hypothesis, we examined 6 normal heart specimens and hearts with congenital cardiovascular malformations, including 5 with pulmonary atresia and an intact ventricular septum, 6 with tetralogy of Fallot and 5 with aortic valvar stenosis. We marked the papillary muscles and the mitral commissures, X-rayed the hearts, and measured the angular positions of the papillary muscles using the midpoint of a chord drawn between the mitral commissures as a reference point. The direction from the midpoint to the lateral commissure was designated as 0 degrees. The data (mean +/- SEM) were analyzed using a computer program (ANOVA). In normal hearts, the anterolateral and posteromedial papillary muscles were positioned, respectively, at 43 +/- 19 degrees and 126 +/- 26 degrees. The positions of the papillary muscles were similar to normal in the hearts with pulmonary atresia (62 +/- 38 degrees and 128 +/- 27 degrees) and tetralogy of Fallot (40 +/- 13 degrees and 130 +/- 37 degrees). In aortic stenosis, the locations of the papillary muscles (-76 +/- 42 degrees and 71 +/- 25 degrees) were significantly different from normal (P less than 0.05). The arc between the papillary muscles was 83 +/- 16 degrees in normals and 147 +/- 45 degrees in aortic stenosis (P less than 0.05). The length of the arc was similar to normal in other heart specimens. Thus, the papillary muscles were abnormally positioned in aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of chick embryo hyperflexion on tracheoesophageal development.

Chick embryos were hyperflexed by placement of a ligature at two critical stages in the development of the foregut, in order to test the theory that esophageal atresia and tracheoesophageal fistula result from embryonic hyperflexion. Only one "H-type" tracheoesophageal fistula was found. There were no significant disturbances of either tracheal or esophageal growth.