Predicting non-equilibrium folding behavior of polymer chains using the steepest-entropy-ascent quantum thermodynamic framework.

The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework is used to explore the influence of heating and cooling on polymer chain folding kinetics. The framework predicts how a chain moves from an initial non-equilibrium state to stable equilibrium along a unique thermodynamic path. The thermodynamic state is expressed by occupation probabilities corresponding to the levels of a discrete energy landscape. The landscape is generated using the Replica Exchange Wang-Landau method applied to a polymer chain represented by a sequence of hydrophobic and polar monomers with a simple hydrophobic-polar amino acid model. The chain conformation evolves as energy shifts among the levels of the energy landscape according to the principle of steepest entropy ascent. This principle is implemented via the SEAQT equation of motion. The SEAQT framework has the benefit of providing insight into structural properties under non-equilibrium conditions. Chain conformations during heating and cooling change continuously without sharp transitions in morphology. The changes are more drastic along non-equilibrium paths than along quasi-equilibrium paths. The SEAQT-predicted kinetics are fitted to rates associated with the experimental intensity profiles of cytochrome c protein folding with Rouse dynamics.

Loss of function in ROBO1 is associated with tetralogy of Fallot and septal defects.

BACKGROUND: Congenital heart disease (CHD) is a common birth defect affecting approximately 1% of newborns. Great progress has been made in elucidating the genetic aetiology of CHD with advances in genomic technology, which we leveraged in recovering a new pathway affecting heart development in humans previously known to affect heart development in an animal model. METHODS: Four hundred and sixteen individuals from Thailand and the USA diagnosed with CHD and/or congenital diaphragmatic hernia were evaluated with chromosomal microarray and whole exome sequencing. The DECIPHER Consortium and medical literature were searched for additional patients. Murine hearts from ENU-induced mouse mutants and transgenic mice were evaluated using both episcopic confocal histopathology and troponin I stained sections. RESULTS: Loss of function ROBO1 variants were identified in three families; each proband had a ventricular septal defect, and one proband had tetralogy of Fallot. Additionally, a microdeletion in an individual with CHD was found in the medical literature. Mouse models showed perturbation of the Slit-Robo signalling pathway, causing septation and outflow tract defects and craniofacial anomalies. Two probands had variable facial features consistent with the mouse model. CONCLUSION: Our findings identify Slit-Robo as a significant pathway in human heart development and CHD.

Predicting Ion Sequestration in Charged Polymers with the Steepest-Entropy-Ascent Quantum Thermodynamic Framework.

The steepest-entropy-ascent quantum thermodynamic framework is used to investigate the effectiveness of multi-chain polyethyleneimine-methylenephosphonic acid in sequestering rare-earth ions (Eu3+) from aqueous solutions. The framework applies a thermodynamic equation of motion to a discrete energy eigenstructure to model the binding kinetics of europium ions to reactive sites of the polymer chains. The energy eigenstructure is generated using a non-Markovian Monte Carlo model that estimates energy level degeneracies. The equation of motion is used to determine the occupation probability of each energy level, describing the unique path through thermodynamic state space by which the polymer system sequesters rare-earth ions from solution. A second Monte Carlo simulation is conducted to relate the kinetic path in state space to physical descriptors associated with the polymer, including the radius of gyration, tortuosity, and Eu-neighbor distribution functions. These descriptors are used to visualize the evolution of the polymer during the sequestration process. The fraction of sequestered Eu3+ ions depends upon the total energy of the system, with lower energy resulting in greater sequestration. The kinetics of the overall sequestration are dependent on the steepest-entropy-ascent principle used by the equation of motion to generate a unique kinetic path from an initial non-equilibrium state.

Quantitative Magnetic Resonance Cerebral Spinal Fluid Flow Properties and Executive Function Cognitive Outcomes in Congenital Heart Disease.

Cerebrospinal fluid (CSF) circulation has recently been shown to be important in nutrient distribution, waste removal, and neurogenesis. Increased CSF volumes are frequently observed in congenital heart disease (CHD) and are associated with neurodevelopmental deficits. This suggests prolonged perturbation to the CSF system and possible interference to its homeostatic function, which may contribute to the neurodevelopmental deficits in CHD. CSF flow has yet to be studied in CHD patients, but the pulsatile flow of CSF throughout the brain is driven mainly by cardiopulmonary circulation. Given the underlying heart defects in CHD, the cardiopulmonary circulatory mechanisms in CHD might be impaired with resultant perturbation on the CSF circulation. In this study, we determine whether CSF flow, using MRI measurements of static and dynamic pulsatile flow, is abnormal in youths with CHD compared to healthy controls in relation to executive cognitive function. CSF flow measurements were obtained on a total of 58 child and young adult participants (CHD=20, healthy controls = 38). The CSF flow was measured across the lumen of the Aqueduct of Sylvius using cardiac-gated phase-contrast MRI at 3.0T. Static pulsatility was characterized as anterograde and retrograde peak velocities, mean velocity, velocity variance measurements, and dynamic pulsatility calculated as each participant's CSF flow deviation from the study cohort's consensus flow measured with root mean squared deviation (RMSD) were obtained. The participants had neurocognitive assessments for executive function with focus on inhibition, cognitive flexibility, and working memory domains. The CHD group demonstrated greater dynamic pulsatility (higher overall flow RMSD over the entire CSF flow cycle) compared to controls (p=0.0353), with no difference detected in static pulsatility measures. However, lower static CSF flow pulsatility (anterograde peak velocity: p=0.0323) and lower dynamic CSF flow pulsatility (RMSD: p=0.0181) predicted poor inhibitory executive function outcome. Taken together, while the whole CHD group exhibited higher dynamic CSF flow pulsatility compared to controls, the subset of CHD subjects with relatively reduced static and dynamic CSF flow pulsatility had the worst executive functioning, specifically the inhibition domain. These findings suggest that altered CSF flow pulsatility may be central to not only brain compensatory mechanisms but can also drive cognitive impairment in CHD. Further studies are needed to investigate possible mechanistic etiologies of aberrant CSF pulsatility (i.e. primary cardiac hemodynamic disturbances, intrinsic brain vascular stiffness, altered visco-elastic properties of tissue, or glial-lymphatic disturbances), which can result in acquired small vessel brain injury (including microbleeds and white matter hyperintensities).

Mitotic Block and Epigenetic Repression Underlie Neurodevelopmental Defects and Neurobehavioral Deficits in Congenital Heart Disease.

Poor neurodevelopment is often observed with congenital heart disease (CHD), especially with mutations in chromatin modifiers. Here analysis of mice with hypoplastic left heart syndrome (HLHS) arising from mutations in Sin3A associated chromatin modifier Sap130 , and adhesion protein Pcdha9, revealed neurodevelopmental and neurobehavioral deficits reminiscent of those in HLHS patients. Microcephaly was associated with impaired cortical neurogenesis, mitotic block, and increased apoptosis. Transcriptional profiling indicated dysregulated neurogenesis by REST, altered CREB signaling regulating memory and synaptic plasticity, and impaired neurovascular coupling modulating cerebral blood flow. Many neurodevelopmental/neurobehavioral disease pathways were recovered, including autism and cognitive impairment. These same pathways emerged from genome-wide DNA methylation and Sap130 chromatin immunoprecipitation sequencing analyses, suggesting epigenetic perturbation. Mice with Pcdha9 mutation or forebrain-specific Sap130 deletion without CHD showed learning/memory deficits and autism-like behavior. These novel findings provide mechanistic insights indicating the adverse neurodevelopment in HLHS may involve cell autonomous/nonautonomous defects and epigenetic dysregulation and suggest new avenues for therapy.

Postnatal Brain Trajectories and Maternal Intelligence Predict Childhood Outcomes in Complex CHD.

Objective: To determine whether early structural brain trajectories predict early childhood neurodevelopmental deficits in complex CHD patients and to assess relative cumulative risk profiles of clinical, genetic, and demographic risk factors across early development. Study Design: Term neonates with complex CHDs were recruited at Texas Children's Hospital from 2005-2011. Ninety-five participants underwent three structural MRI scans and three neurodevelopmental assessments. Brain region volumes and white matter tract fractional anisotropy and radial diffusivity were used to calculate trajectories: perioperative, postsurgical, and overall. Gross cognitive, language, and visuo-motor outcomes were assessed with the Bayley Scales of Infant and Toddler Development and with the Wechsler Preschool and Primary Scale of Intelligence and Beery-Buktenica Developmental Test of Visual-Motor Integration. Multi-variable models incorporated risk factors. Results: Reduced overall period volumetric trajectories predicted poor language outcomes: brainstem ((ß, 95% CI) 0.0977, 0.0382-0.1571; p = 0.0022) and white matter (0.0023, 0.0001-0.0046; p = 0.0397) at 5 years; brainstem (0.0711, 0.0157-0.1265; p = 0.0134) and deep grey matter (0.0085, 0.0011-0.0160; p = 0.0258) at 3 years. Maternal IQ was the strongest contributor to language variance, increasing from 37% at 1 year, 62% at 3 years, and 81% at 5 years. Genetic abnormality's contribution to variance decreased from 41% at 1 year to 25% at 3 years and was insignificant at 5 years. Conclusion: Reduced postnatal subcortical-cerebral white matter trajectories predicted poor early childhood neurodevelopmental outcomes, despite high contribution of maternal IQ. Maternal IQ was cumulative over time, exceeding the influence of known cardiac and genetic factors in complex CHD, underscoring the importance of heritable and parent-based environmental factors.

Graphene oxide-coated Ag-TiO2 hybrid nanocomposites for superior photocatalytic activity.

Graphene oxide (GO) has now emerged as one of the most promising materials in different areas such as photocatalysis, adsorption, and energy storage due to its high surface area, unique layered structure, etc. Among various types of precursors, anthracite coal has attracted a lot of attention nowadays as it affords GO a high concentration of sp2 carbons resulting in high conductivity and superior absorbance in the visible region. In this report, we have prepared GO-TiO2 nanocomposites as it is supposed to possess high photocatalytic activity owing to facile electron transmission from the conduction band of TiO2 to the GO surface resulting in a much lower degree of electron-hole pair recombination. To boost the photocatalytic activity further, TiO2 was coated with Ag nanoparticles as well. These hybrid structures were characterized by different analytical techniques, for example, XRD, HR-TEM, SEM, and Raman spectroscopy. The XRD pattern of these composites consists of characteristic peaks corresponding to GO, TiO2, and Ag. The HR-TEM studies confirm the presence of GO layers, cube-shaped TiO2, and spherical Ag nanoparticles. Phenol and 4-nitrophenol have been used as model pollutants to evaluate the photooxidation efficiencies under both UV and visible light irradiation. Under UV irradiation, the GO/Ag-TiO2 ternary nanocomposite shows better photooxidation efficiency (62%) compared to Ag-TiO2 (38%), GO-TiO2 (9%), GO (17%), and TiO2 (8%) toward phenol degradation. The GO/Ag-TiO2 is also having the highest photocatalytic activity toward the removal of phenol under visible light irradiation (34%). The ternary heterostructure (85%) also possesses superior photooxidation activity compared to Ag-TiO2 (44%) and GO-TiO2 (71%) toward the degradation of p-nitrophenol under UV light radiation for 60 min. The above observation reveals that the cooperative effect of Ag, TiO2, and GO is playing a crucial role to result in the high photooxidation activity of the GO/Ag-TiO2 hetero-nanocomposites.

Predicting Polymer Brush Behavior in Solvents Using the Steepest-Entropy-Ascent Quantum Thermodynamic Framework.

The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework is utilized to study the effects of temperature on polymer brushes. The brushes are represented by a discrete energy spectrum, and energy degeneracies obtained through the replica-exchange Wang-Landau algorithm. The SEAQT equation of motion is applied to the density of states to establish a unique kinetic path from an initial thermodynamic state to a stable equilibrium state. The kinetic path describes the brush's evolution in state space, as it interacts with a thermal reservoir. The predicted occupation probabilities along the kinetic path are used to determine the expected thermodynamic and structural properties. The polymer density profile of a polystyrene brush in cyclohexane solvent is predicted using the equation of motion, and it agrees qualitatively with the experimental density profiles. The Flory-Huggins parameter chosen to describe brush-solvent interactions affects the solvent distribution in the brush but has a minimal impact on the polymer density profile. Three types of nonequilibrium kinetic paths with differing amounts of entropy production are considered: a heating path, a cooling path, and a heating-cooling path. Properties such as tortuosity, radius of gyration, brush density, solvent density, and brush chain conformations are calculated for each path.

Predicting defect stability and annealing kinetics in two-dimensional PtSe2using steepest entropy ascent quantum thermodynamics.

The steepest-entropy-ascent quantum thermodynamic (SEAQT) framework was used to calculate the stability of a collection of point defects in 2D PtSe2and predict the kinetics with which defects rearrange during thermal annealing. The framework provides a non-equilibrium, ensemble-based framework with a self-consistent link between mechanics (both quantum and classical) and thermodynamics. It employs an equation of motion derived from the principle of steepest entropy ascent (maximum entropy production) to predict the time evolution of a set of occupation probabilities that define the states of a system undergoing a non-equilibrium process. The system is described by a degenerate energy landscape of eigenvalues, and the entropy is found from the occupation probabilities and the eigenlevel degeneracies. Scanning tunneling microscopy was used to identify the structure and distribution of point defects observed experimentally in a 2D PtSe2film. A catalog of observed defects includes six unique point defects (vacancies and anti-site defects on Pt and Se sublattices) and twenty combinations of multiple point defects in close proximity. The defect energies were estimated with density functional theory, while the degeneracies, or density of states, for the 2D film with all possible combinations or arrangements of cataloged defects was constructed using a non-Markovian Monte-Carlo approach (i.e. the Replica-Exchange-Wang-Landau algorithm (Vogelet al2013Phys. Rev. Lett.110210603)) with a q-state Potts model. The energy landscape and associated degeneracies were determined for a 2D PtSe2film two molecules thick and30×30unit cells in area (total of 5400 atoms). The SEAQT equation of motion was applied to the energy landscape to determine how an arbitrary density and arrangement of the six defect types evolve during annealing. Two annealing processes were modeled: heating from 77 K (-196 ∘C) to 523 K (250 ∘C) and isothermal annealing at 523 K. The SEAQT framework predicted defect configurations, which were consistent with experimental STM images.

Impact of COVID-19 related maternal stress on fetal brain development: A Multimodal MRI study.

Background: Disruptions in perinatal care and support due to the COVID-19 pandemic was an unprecedented but significant stressor among pregnant women. Various neurostructural differences have been re-ported among fetuses and infants born during the pandemic compared to pre-pandemic counterparts. The relationship between maternal stress due to pandemic related disruptions and fetal brain is yet unexamined. Methods: Pregnant participants with healthy pregnancies were prospectively recruited in 2020-2022 in the greater Los Angeles Area. Participants completed multiple self-report assessments for experiences of pandemic related disruptions, perceived stress, and coping behaviors and underwent fetal MRI. Maternal perceived stress exposures were correlated with quantitative multimodal MRI measures of fetal brain development using ltivariate models. Results: Fetal brain stem volume increased with increased maternal perception of pandemic related stress positively correlated with normalized fetal brainstem volume (suggesting accelerated brainstem maturation). In contrast, increased maternal perception of pandemic related stress correlated with reduced global fetal brain temporal functional variance (suggesting reduced functional connectivity). Conclusions: We report alterations in fetal brainstem structure and global functional fetal brain activity associated with increased maternal stress due to pandemic related disruptions, suggesting altered fetal programming. Long term follow-up studies are required to better understand the sequalae of these early multi-modal brain disruptions among infants born during the COVID-19 pandemic.

Impact of COVID-19 Related Maternal Stress on Fetal Brain Development: A Multimodal MRI Study.

BACKGROUND: Disruptions in perinatal care and support due to the COVID-19 pandemic was an unprecedented but significant stressor among pregnant women. Various neurostructural differences have been re-ported among fetuses and infants born during the pandemic compared to pre-pandemic counterparts. The relationship between maternal stress due to pandemic related disruptions and fetal brain is yet unexamined. METHODS: Pregnant participants with healthy pregnancies were prospectively recruited in 2020-2022 in the greater Los Angeles Area. Participants completed multiple self-report assessments for experiences of pandemic related disruptions, perceived stress, and coping behaviors and underwent fetal MRI. Maternal perceived stress exposures were correlated with quantitative multimodal MRI measures of fetal brain development using multivariate models. RESULTS: Increased maternal perception of pandemic related stress positively correlated with normalized fetal brainstem volume (suggesting accelerated brainstem maturation). In contrast, increased maternal perception of pandemic related stress correlated with reduced global fetal brain temporal functional variance (suggesting reduced functional connectivity). CONCLUSIONS: We report alterations in fetal brainstem structure and global functional fetal brain activity associated with increased maternal stress due to pandemic related disruptions, suggesting altered fetal programming. Long term follow-up studies are required to better understand the sequalae of these early multi-modal brain disruptions among infants born during the COVID-19 pandemic.

Clinical factors associated with microstructural connectome related brain dysmaturation in term neonates with congenital heart disease.

Objective: Term congenital heart disease (CHD) neonates display abnormalities of brain structure and maturation, which are possibly related to underlying patient factors, abnormal physiology and perioperative insults. Our primary goal was to delineate associations between clinical factors and postnatal brain microstructure in term CHD neonates using diffusion tensor imaging (DTI) magnetic resonance (MR) acquisition combined with complementary data-driven connectome and seed-based tractography quantitative analyses. Our secondary goal was to delineate associations between mild dysplastic structural brain abnormalities and connectome and seed-base tractography quantitative analyses. These mild dysplastic structural abnormalities have been derived from prior human infant CHD MR studies and neonatal mouse models of CHD that were collectively used to calculate to calculate a brain dysplasia score (BDS) that included assessment of subcortical structures including the olfactory bulb, the cerebellum and the hippocampus. Methods: Neonates undergoing cardiac surgery for CHD were prospectively recruited from two large centers. Both pre- and postoperative MR brain scans were obtained. DTI in 42 directions was segmented into 90 regions using a neonatal brain template and three weighted methods. Clinical data collection included 18 patient-specific and 9 preoperative variables associated with preoperative scan and 6 intraoperative (e.g., cardiopulmonary bypass and deep hypothermic circulatory arrest times) and 12 postoperative variables associated with postoperative scan. We compared patient specific and preoperative clinical factors to network topology and tractography alterations on a preoperative neonatal brain MRI, and intra and postoperative clinical factors to network topology alterations on postoperative neonatal brain MRI. A composite BDS was created to score abnormal findings involving the cerebellar hemispheres and vermis, supratentorial extra-axial fluid, olfactory bulbs and sulci, hippocampus, choroid plexus, corpus callosum, and brainstem. The neuroimaging outcomes of this study included (1) connectome metrics: cost (number of connections) and global/nodal efficiency (network integration); (2) seed based tractography methods of fractional anisotropy (FA), radial diffusivity, and axial diffusivity. Statistics consisted of multiple regression with false discovery rate correction (FDR) comparing the clinical risk factors and BDS (including subcortical components) as predictors/exposures and the global connectome metrics, nodal efficiency, and seed based- tractography (FA, radial diffusivity, and axial diffusivity) as neuroimaging outcome measures. Results: A total of 133 term neonates with complex CHD were prospectively enrolled and 110 had analyzable DTI. Multiple patient-specific factors including d-transposition of the great arteries (d-TGA) physiology and severity of impairment of fetal cerebral substrate delivery (i.e., how much the CHD lesion alters typical fetal circulation such that the highest oxygen and nutrient rich blood from the placenta are not directed toward the fetal brain) were predictive of preoperative reduced cost (p < 0.0073) and reduced global/nodal efficiency (p < 0.03). Cardiopulmonary bypass time predicted postoperative reduced cost (p < 0.04) and multiple postoperative factors [extracorporeal membrane oxygenation (ECMO), seizures and cardiopulmonary resuscitation (CPR)] were predictive of postoperative reduced cost and reduced global/nodal efficiency (p < 0.05). Anthropometric measurements (weight, length, and head size) predicted tractography outcomes. Total BDS was not predictive of brain network topology. However, key subcortical components of the BDS score did predict key global and nodal network topology: abnormalities of the cerebellum predicted reduced cost (p < 0.0417) and of the hippocampus predicted reduced global efficiency (p < 0.0126). All three subcortical structures predicted unique alterations of nodal efficiency (p < 0.05), including hippocampal abnormalities predicting widespread reduced nodal efficiency in all lobes of the brain, cerebellar abnormalities predicting increased prefrontal nodal efficiency, and olfactory bulb abnormalities predicting posterior parietal-occipital nodal efficiency. Conclusion: Patient-specific (d-TGA anatomy, preoperative impairment of fetal cerebral substrate delivery) and postoperative (e.g., seizures, need for ECMO, or CPR) clinical factors were most predictive of diffuse postnatal microstructural dysmaturation in term CHD neonates. Anthropometric measurements (weight, length, and head size) predicted tractography outcomes. In contrast, subcortical components (cerebellum, hippocampus, olfactory) of a structurally based BDS (derived from CHD mouse mutants), predicted more localized and regional postnatal microstructural differences. Collectively, these findings suggest that brain DTI connectome and seed-based tractography are complementary techniques which may facilitate deciphering the mechanistic relative contribution of clinical and genetic risk factors related to poor neurodevelopmental outcomes in CHD.

Low-temperature atomistic spin relaxation and non-equilibrium intensive properties using steepest-entropy-ascent quantum-inspired thermodynamics modeling.

The magnetization of body-centered cubic iron at low temperatures is calculated with the steepest-entropy-ascent quantum thermodynamics (SEAQT) framework. This framework assumes that a thermodynamic property in an isolated system traces the path through state space with the greatest entropy production. Magnetization is calculated from the expected value of a thermodynamic ensemble of quantized spin waves based on the Heisenberg spin model applied to an ensemble of coupled harmonic oscillators. A realistic energy landscape is obtained from a magnon dispersion relation calculated using spin-density-functional-theory. The equilibrium magnetization as well as the evolution of magnetization from a non-equilibrium state to equilibrium are calculated from the path of steepest entropy ascent determined from the SEAQT equation of motion in state space. The framework makes it possible to model the temperature and time-dependence of magnetization without a detailed description of magnetic damping. The approach is also used to define intensive properties (temperature and magnetic field strength) that are fundamentally, i.e. canonically or grand canonically, valid for any non-equilibrium state. Given the assumed magnon dispersion relation, the SEAQT framework is used to calculate the equilibrium magnetization at different temperatures and external magnetic fields and the results are shown to closely agree with experiment for temperatures less than 500 K. The time-dependent evolution of magnetization from different initial states and interactions with a reservoir is also predicted.

Predicting continuous and discontinuous phase decompositions using steepest-entropy-ascent quantum thermodynamics.

The decomposition kinetics of a solid solution into separate phases are analyzed with an equation of motion initially developed to account for dissipative processes in quantum systems. This equation and the steepest-entropy-ascent quantum thermodynamic framework of which it is a part make it possible to track kinetic processes in systems at nonequilibrium while retaining the framework of classical equilibrium thermodynamics. The general equation of motion is particularized for the case of the decomposition of a binary alloy, and a solution model is used to build an approximate energy eigenstructure, or pseudoeigenstructure, for the alloy system. This equation is then solved with the pseudoeigenstructure to obtain a unique reaction path and the decomposition kinetics of the alloy. For a hypothetical solid solution with a miscibility gap at low temperatures, the conditions under which this framework predicts a continuous transformation path (spinodal decomposition) or a discontinuous one (nucleation and growth) are demonstrated.

A method for predicting non-equilibrium thermal expansion using steepest-entropy-ascent quantum thermodynamics.

Steepest-entropy-ascent quantum thermodynamics (SEAQT) is an intriguing approach that describes equilibrium and dynamic processes in a self-consistent way. To date, it has been applied primarily to gas phase systems because of the difficulty in generating the complex eigenstructures (eigenvalues and eigenfunctions) associated with solid or liquid phases. In this contribution, the SEAQT modeling is extended to the solid phase by constructing a so-called pseudo-eigenstructure, and its applicability is demonstrated by calculating the thermal expansion of metallic silver for three cases: (a) stable equilibrium, (b) along three irreversible paths from different initial non-equilibrium states to stable equilibrium, and (c) along an irreversible path between two stable equilibrium states. The SEAQT framework with an anharmonic pseudo-eigenstructure predicts reasonable values for the equilibrium thermal expansion. For the irreversible cases considered, the SEAQT approach makes it possible to predict the time-dependence of lattice relaxations from the initial state to the final equilibrium state.

The complex genetics of hypoplastic left heart syndrome.

Congenital heart disease (CHD) affects up to 1% of live births. Although a genetic etiology is indicated by an increased recurrence risk, sporadic occurrence suggests that CHD genetics is complex. Here, we show that hypoplastic left heart syndrome (HLHS), a severe CHD, is multigenic and genetically heterogeneous. Using mouse forward genetics, we report what is, to our knowledge, the first isolation of HLHS mutant mice and identification of genes causing HLHS. Mutations from seven HLHS mouse lines showed multigenic enrichment in ten human chromosome regions linked to HLHS. Mutations in Sap130 and Pcdha9, genes not previously associated with CHD, were validated by CRISPR-Cas9 genome editing in mice as being digenic causes of HLHS. We also identified one subject with HLHS with SAP130 and PCDHA13 mutations. Mouse and zebrafish modeling showed that Sap130 mediates left ventricular hypoplasia, whereas Pcdha9 increases penetrance of aortic valve abnormalities, both signature HLHS defects. These findings show that HLHS can arise genetically in a combinatorial fashion, thus providing a new paradigm for the complex genetics of CHD.

Vision examinations for all children entering public school--the new Kentucky law.

BACKGROUND: Kentucky was the first state in the United States to pass a law requiring an eye examination by an optometrist or ophthalmologist for each child entering public school, public preschool, or Head Start program for the first time. The law became effective on July 15, 2000. METHOD: Forty-three of 334 Kentucky Optometric Association members were surveyed by the Kentucky Optometric Association. They practiced in 37 of 120 counties throughout Kentucky. Eye examinations for 5,316 children entering the Kentucky school system for the first time were reviewed. The children were divided into groups of 3-year-olds, 4-year-olds, 5-year-olds, and 6-year-olds and older. The survey summarized data collected during the period of July 15, 2000 through April 1, 2001. RESULTS: Based on the survey of the clinical assessments of 5,316 eye examinations, a total of 740 children were prescribed spectacle lenses, 181 were diagnosed with amblyopia, 123 children were diagnosed with strabismus, and 44 were diagnosed with other eye diseases. Children in the 6-years-old and above age group were statistically prescribed more spectacle prescriptions than were children ages 3, 4, or 5 years of age. The number of spectacle lens prescriptions, strabismus, amblyopia, and eye diseases diagnosed was independent of county income levels. CONCLUSION: This survey of children entering the Kentucky public school system for the first time showed that 13.92% of the children were prescribed spectacle lenses, 3.40% were diagnosed with amblyopia, and 2.31% were diagnosed with strabismus.