Early Pulmonary Hypertension in Preterm Infants.

Pulmonary hypertension (PH) in preterm neonates has multifactorial pathogenesis with unique characteristics. Premature surfactant-deficient lungs are injured following exposure to positive pressure ventilation and high oxygen concentrations resulting in variable phenotypes of PH. The prevalence of early PH is variable and reported to be between 8% and 55% of extremely preterm infants. Disruption of the lung development and vascular signaling pathway could lead to abnormal pulmonary vascular transition. The management of early PH and the off-label use of selective pulmonary vasodilators continue to be controversial.

Cell-shaped silicon-on-insulator microdosimeters: characterization and response to 239PuBe irradiations.

This work tested the feasibility of a silicon-on-insulator microdosimeter, which mimics the size and shape of specific cells within the human body, to determine dose equivalent from neutron irradiation. The microdosimeters were analyzed in terms of their basic diode characteristics, i.e., leakage current as a function of bias voltage. Lineal energy spectra were acquired using two different converter layers placed atop the microdosimeter: a tissue-substitute converter made from high-density polyethylene, and a boron converter consisting of epoxy coated with boron powder. The spectra were then converted into absorbed dose and dose equivalent. Experimental results were compared to Monte Carlo simulations of the neutron irradiations, revealing good agreement. Uncertainty in the dose equivalent determinations was 7.5% when using the cell-shaped microdosimeter with the tissue-substitute converter and 13.1% when using the boron converter. This work confirmed that the SOI approach to cell-mimicking microdosimetry is feasible.

Analytical model for ion stopping power and range in the therapeutic energy interval for beams of hydrogen and heavier ions.

Many different approaches exist to calculate stopping power and range of protons and heavy charged particles. These methods may be broadly categorized as physically complete theories (widely applicable and complex) or semi-empirical approaches (narrowly applicable and simple). However, little attention has been paid in the literature to approaches that are both widely applicable and simple. We developed simple analytical models of stopping power and range for ions of hydrogen, carbon, iron, and uranium that spanned intervals of ion energy from 351 keV u(-1) to 450 MeV u(-1) or wider. The analytical models typically reproduced the best-available evaluated stopping powers within 1% and ranges within 0.1 mm. The computational speed of the analytical stopping power model was 28% faster than a full-theoretical approach. The calculation of range using the analytic range model was 945 times faster than a widely-used numerical integration technique. The results of this study revealed that the new, simple analytical models are accurate, fast, and broadly applicable. The new models require just 6 parameters to calculate stopping power and range for a given ion and absorber. The proposed model may be useful as an alternative to traditional approaches, especially in applications that demand fast computation speed, small memory footprint, and simplicity.

Temporal Profile of Early Pulmonary Hypertension in Preterm Infants.

Objective The objective of this study was to study the temporal profile of pulmonary hypertension (PH) in preterm infants. Study Design Infants < 28 weeks were screened for early PH at 10 to 14 days of life. Infants with early PH (n = 10) and gestationally matched controls (n = 18) underwent serial echocardiography every 7 to 10 days until 36 weeks postmenstrual age. Results Groups with and without early PH were comparable except for higher Fio 2 by day 10 among infants with early PH. Early PH was moderate in extent and resolved in all infants with recurrence in one infant. Among infants without early PH, five infants developed late PH. In both groups, development of late PH occurred in association with important neonatal morbidities, such as patent ductus arteriosus, bronchopulmonary dysplasia, and infection. Conclusion Early moderate PH among preterm infants resolves over a variable time period but recurrence is possible. Late PH can appear during the course of hospitalization in association with other clinical morbidities.

Individuals Are Continents; or, Why It's Time to Retire the Island Approach to Addiction.

Individuals are not island isolates. This is an old insight that finds expression in indigenous worldviews, ancient philosophies, religious doctrine, and modern social theories. Even so, science remains encumbered by the false dichotomies and reductionism inherited from the capitalist revolution and reinforced by the fragmentation of modern life. This same heritage encumbers addiction research and efforts to devise effective interventions. It does so because the island concept at its core filters out the most decisive factors contributing to addiction. We therefore recommend its replacement with what we call the continental concept of the individual, which conceives of society and the natural environment as extensions of individual corporeal bodies. Such a theoretical reorientation has significant implications for intervention research and practice. More specifically, it radically expands the scope of what constitutes a valid intervention in the first place. We call this reorientation the continental approach to drug addiction.

Pulmonary hypertension in preterm infants: prevalence and association with bronchopulmonary dysplasia.

OBJECTIVE: To determine whether early pulmonary hypertension (PH) at 10-14 days of life in preterm infants is associated with bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age (PMA). STUDY DESIGN: This was a prospective observational cohort study of infants <28 weeks' gestation. Exclusion criteria were any major anomaly, genetic syndrome, or death before the initial echocardiogram. Echocardiograms were performed between 10 and 14 days of life and at 36 weeks' PMA to assess PH. BPD and its severity were determined at 36 weeks PMA by the National Institutes of Health workshop definition. RESULTS: From March 2011 to April 2013, of 146 consecutively admitted infants <28 weeks, 120 were enrolled. One infant was excluded, 17 did not consent, and 8 died before undergoing a study echocardiogram. At 10-14 days of life, 10 infants had early PH (8%). Male sex (56% vs 40%), gestational age (26(+2) ± 1(+2) vs 25(+6) ± 1(+4) weeks), birth weight (837 ± 205 g vs 763 ± 182 g), and small for gestational age (14% vs 20%) were not significantly different among infants with no PH and early PH, respectively. Infants with early PH required >0.3 fraction of inspired oxygen by day 10 of life (70% vs 27%, P < .01). Moderate/severe BPD or death was greater among infants with early PH (90%) compared with no PH (47%, relative risk 1.9, 95% CI 1.43-2.53). CONCLUSION: In this prospective, single-center cohort, early PH was associated with moderate/severe BPD or death at 36 weeks' PMA.

Exercise-limiting symptoms in children.

Transient exercise-related symptoms are common in children and adolescents and only rarely reflect underlying cardiac and pulmonary disease processes. Most symptoms occurring during exercise reflect changes related to normal exercise physiology, changes in level of competition, and musculoskeletal and developmental factors. A rational approach to screening for potentially life-threatening cardiac conditions and exercise-induced bronchospasm is important to minimize the risk of misdiagnosis and to keep the young athlete active.

Intervertebral motion between flexion and extension in asymptomatic individuals.

STUDY DESIGN: Measure and analyze variation in intervertebral motion in asymptomatic subjects. OBJECTIVES: Gain further insight into intervertebral motion during flexion and extension in asymptomatic individuals, identify factors that contribute to variation in motion, and establish a quantitative database using a clinically practical imaging tool. SUMMARY OF BACKGROUND DATA: Several authors have reported on normal values for intervertebral motion during flexion and extension of the cervical spine. However, the sources of the wide variations in intervertebral motion are poorly understood. METHODS: Fluoroscopic images of the cervical spine in maximum flexion and extension were analyzed for 140 asymptomatic volunteers using a validated and clinically applicable image analysis system. Several independent variables were analyzed for their contribution to variation in motion. The dependent variables studied included sagittal plane rotation and translation, and displacements between vertebrae measured at the anterior and posterior aspects of each motion segment. RESULTS: There was considerable variation in measured intervertebral motion. Intervertebral level and total gross rotation between C2 and C6 significantly affected all measures of intervertebral motion. The intervertebral motion measures were all interrelated. After adjusting for differences in gross motion between C2 and C6, intervertebral levels and the three displacement measures could be used to explain almost 90% of the variation in sagittal plane intervertebral rotations. In addition, the data suggest that currently accepted clinical guidelines for shear should be raised at all levels except C6-C7. CONCLUSIONS: A database describing intervertebral motion in asymptomatic subjects representing both sexes and a wide age range was established that should aid in interpreting intervertebral motion in patients. Evaluating various aspects of intervertebral motion may improve the clinical efficacy of radiographic flexion-extension studies of the cervical spine.

Intracardiac yolk sac tumor and dysrhythmia as an etiology of pediatric syncope.

This report describes a new etiology of pediatric syncope. Epilepsy, brain anomalies, infection, electrolyte abnormalities, and trauma are commonly identified etiologies of seizures in the pediatric population. We report here a child with third-degree heart block and right ventricular outflow tract obstruction related to an intracardiac tumor presenting with syncope and seizure-like activity. Echocardiography revealed a large (3 x 8-cm) intracardiac mass filling the right atrium, extending across the tricuspid valve into the right ventricle and crossing the atrial septum into the left atrium, extending into the left ventricular outflow tract. She underwent emergent cardiopulmonary bypass with removal of the majority of the tumor mass, clearing both the left and right ventricular outflow tracts of obstruction and repairing the tricuspid valve. Postoperative cardiac conduction remained blocked and required permanent pacing. The initial serum alpha-fetoprotein level was grossly elevated, and the tumor showed characteristic histopathologic features of a yolk sac tumor. Four years after the completion of her chemotherapy, she remains clinically well, with no evidence of recurrent tumor by echocardiography or radiographic studies, and her alpha-fetoprotein remains in the normal range. The clinical manifestations of tumor infiltration of the heart with complete heart block resulting in loss of consciousness with tonic-clonic movements are detailed. Although rare, cardiac syncope has multiple known causes and should be suspected in any patient with sudden loss of consciousness and pallor. In the pediatric population, cardiac rhythm disturbances are typically the result, rather than the cause, of acute cardiac emergencies. Pediatricians should be aware of depressed cardiac output and dysrhythmias as etiologies of new-onset syncope. Evaluation should include a cardiac assessment with electrocardiogram to exclude a life-threatening arrhythmia as a potential cause.

Metalloporphyrin probes for antimalarial drug action.

Metal-substituted protoporphyrin IXs (Co(III)PPIX (1), Cr(III)PPIX (2), Mn(III)PPIX (3), Cu(II)PPIX (4), Mg(II)PPIX (5), Zn(II)PPIX (6) and Sn(IV)PPIX (7)), phthalocyanine tetrasulfonates (PcS (8) and Ni(II)PcS (9)), and anionic and cationic porphyrins (meso-tetra(4-sulfonatophenyl)porphine (TPPS4, 10), meso-tetra(4-carboxyphenyl)porphine (TPPC4, 11), tetrakis(4-N-trimethylaminophenyl)porphine (TMAP, 12) and meso-tetra(N-methyl-4-pyridyl)porphine (TMPyP4, 13)) have been used as probes to compare two different assays for the inhibition of beta-hematin formation. The results demonstrate that the efficacy of these probes in either the beta-hematin inhibition assay (9, 7, 6, 5>4>11, 3>10, 8>2, 1; 12 and 13 did not inhibit.) or the bionucleating template assay (8>1>11>9, 2>4>3>7>10>5>6; 12 and 13 did not inhibit.) differ significantly. These differences are examined in light of possible interactions between the inhibitor probes, heme, beta-hematin and the bionucleating template. This detailed analysis highlights the fact that while dominant modes of interactions may be occasionally identified, the precise mechanism of inhibition undoubtedly consists of the interplay between multiple interactions.

Hepatic dysfunction following the Fontan procedure.

OBJECTIVES: The Fontan procedure offers a palliation for the hemodynamic derangements associated with congenital heart lesions characterized by a single functional ventricle, but it causes a chronically elevated systemic venous pressure that may result in hepatic congestion. The objective of this study was to characterize hepatic function and its relationship to cardiac function in children who had undergone the Fontan procedure. METHODS: In a cross-sectional study of 11 children aged 38 months to 216 months (mean, 149 months), the authors evaluated indices of cardiac and hepatic function, including galactose clearance, Doppler hepatic ultrasonography, synthetic function, and markers of liver injury, at 9 months to 176 months (mean, 100 months) after children had undergone the Fontan procedure. RESULTS: The most common biochemical abnormality of hepatic function was a prolongation of the prothrombin time and a low factor V level. There was a trend toward progressive abnormality in prothrombin time with increasing interval since the Fontan procedure. Galactose elimination half-life and galactose elimination capacity were inversely correlated with the time after Fontan (R2= 0.65, P = 0.004). There was no relationship between cardiac functional measurements and liver function. CONCLUSIONS: Prothrombin time and galactose elimination half-life are abnormal in children who have undergone the Fontan procedure and may be useful markers of hepatic function in the longitudinal assessment of these patients.