bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical Power to Detect Genetic and Environmental Influences in the Presence of Data Missing at Random
Authors: Derks Eske M. , Dolan Conor V. , Boomsma Dorret I. 
Published: February 2007

AbstractWe study the situation in which a cheap measure (X) is observed in a large, representative twin sample, and a more expensive measure (Y) is observed in a selected subsample. The aim of this study is to investigate the optimal selection design in terms of the statistical power to detect genetic and environmental influences on the variance of Y and on the covariance of X and Y. Data were simulated for 4000 dizygotic and 2000 monozygotic twins. Missingness (87% vs. 97%) was then introduced in accordance with 7 selection designs: (i) concordant low + individual high design; (ii) extreme concordant design; (iii) extreme concordant and discordant design (EDAC); (iv) extreme discordant design; (v) individual score selection design; (vi) selection of an optimal number of MZ and DZ twins; and (vii) missing completely at random. The statistical power to detect the influence of additive and dominant genetic and shared environmental effects on the variance of Y and on the covariance between X and Y was investigated. The best selection design is the individual score selection design. The power to detect additive genetic effects is high irrespective of the percentage of missingness or selection design. The power to detect shared environmental effects is acceptable when the percentage of missingness is 87%, but is low when the percentage of missingness is 97%, except for the individual score selection design, in which the power remains acceptable. The power to detect D is low, irrespective of selection design or percentage of missingness. The individual score selection design is therefore the best design for detecting genetic and environmental influences on the variance of Y and on the covariance of X and Y. However, the EDAC design may be preferred when an additional purpose of a study is to detect quantitative trait loci effects.
Genetic and Environmental Contributions to Pathological Gambling Symptoms in a 10-Year Follow-Up
Authors: Xian Hong , Scherrer Jeffrey F. , Slutske Wendy S. , Shah Kamini R. , Volberg Rachel , Eisen Seth A. 
Published: February 2007

AbstractProblem (P) and pathological gambling (PG) symptoms wax and wane. Past symptoms are a risk for future symptoms even after controlling for familial influences. To address the genetic architecture of lifetime PG and current PG symptoms, we tested for common and unique genetic factors to lifetime PG symptoms at baseline and past year PG symptoms at 10-year follow-up. Diagnostic and Statistical Manual of Mental Disorders (3rd ed., Rev.; DSM-III-R; American Psychiatric Association, 1987) lifetime criteria of one or more PG symptoms were derived in 1992 and past year PG symptoms in 2002 from 1675 individual twins from the Vietnam Era Twin Registry. Cholesky decomposition models were fit to baseline and past year PG symptoms. Under the best fitting model we observed that 49% of the risk for one or more baseline PG symptoms in 1992 was due to a genetic factor and 51% of the risk was due to a unique environmental factor. All of the genetic variance (57.5%) in risk to past year PG symptoms in 2002 was common with baseline PG symptoms. Unique environment accounted for the remaining variance in past year PG symptoms with 13% common to baseline and 30% specific to past year PG symptoms. The genetic contributions to lifetime and past year gambling symptoms 10 years later are similar. There is no evidence for genetic contributions unique to past year PG symptoms. However, most of the unique environmental influences to past year PG are not shared with lifetime PG. This may reflect the changed social–cultural environment between 1992 and 2002, characterized by increasing access to legalized gambling.
Covariance of Isometric and Dynamic Arm Contractions: Multivariate Genetic Analysis
Authors: Mars Gunther De , Thomis Martine A. I. , Windelinckx An , Leemputte Marc Van , Maes Hermine H. , Blimkie Cameron J. , Claessens Albrecht L. , Vlietinck Robert , Beunen Gaston 
Published: February 2007

AbstractThe purpose of the present study was to examine genetic and environmental contributions to individual differences in maximal isometric, concentric and eccentric muscle strength and muscle cross-sectional area (MCSA) of the elbow flexors. A generality versus specificity hypothesis was explored to test whether the 4 strength variables share a genetic component or common factors in the environment or whether the genetic/environmental factors are specific for each strength variable. The 4 variables under study were measured in 25 monozygotic and 16 dizygotic male Caucasian twin pairs (22.4 ± 3.7 years). The multivariate genetic analyses showed that all 4 variables shared a genetic and environmental component, which accounted for 43% and 6% in MCSA (h2= 81%), 47% and 20% in eccentric (h2= 65%), 58% and 4% in isometric (h2= 70%) and 32% and 1% in concentric strength (h2= 32%) respectively. The remaining variation was accounted for by contraction type specific and muscle cross-sectional area specific genetic and environmental effects, which accounted for 38% and 14% in MCSA, 18% and 15% in eccentric, 12% and 26% in isometric and 0% and 67% in concentric strength respectively. This exploratory multivariate study suggests shared pleiotropic gene action for MCSA, eccentric, isometric and concentric strength, with a moderate to high genetic contribution to the variability of these characteristics.
Vanishing Twin: A Possible Cause of Cerebral Impairment
Authors: Anand Dhullipala , Platt Mary Jane , Pharoah Peter O. D. 
Published: February 2007

AbstractFetal death in a twin conception during second and third trimester is associated with increased risk of cerebral injury in the surviving twin. The aim of this study is to test the hypothesis that even early fetal losses as a ‘vanishing’ twin may be associated with an increased risk of cerebral impairment in the surviving twin. The study population comprised 362 pregnant women attending Liverpool Women's Hospital recruited between 1999 and 2001. Women were classified according to the first ultrasound scan into 3 groups: vanishing twin, twin and singleton. The vanishing twin group was further subdivided into ‘definite’ and ‘probable’. Children from these pregnancies were assessed at 1 year of age for their development and neurological function using the Griffiths Mental and Developmental Scales and Optimality score. Children from 229 pregnancies (63.2%) attended the assessment. Information on children from a further 21 (5.8%) pregnancies was obtained through a review of hospital records. Cerebral impairment was found in 2 children from the vanishing twin group, 2 from the twin group and none from the singleton group. When cases with definite vanishing twin are considered there is a significant difference between the vanishing twin and singleton group (relative risk 6.1; 95% confidence interval 1.5–8.3; p = .03). An additional study with an increased sample size would enable a more robust conclusion.
Ultrasound to Identify Cord Knotting in Monoamniotic Monochorionic Twins
Authors: Deutsch Aaron B. , Miller Evan , Spellacy William N. , Mabry Rhonda 
Published: February 2007

AbstractThis case report demonstrates the use of ultrasound and doppler flow in the management of mono-amniotic monochorionic (M/M) twins. M/M twinning is a rare but significant event. It is associated with high rates of fetal mortality, most commonly cited at anywhere from between 30% and 70%. A common cause of death is cord entanglement. The case presented is that of a 19-year-old gravida 1 at 30 weeks with M/M twins in which multiple cord knots were found by ultrasound color doppler flow after variable fetal heart rate decelerations occurred. This prompted a decision for immediate cesarean delivery with normal fetal outcomes. Improvements in perinatal imaging systems are therefore beneficial in the management of M/M twins.
Pattern of Twin Placentation in Ghana
Authors: Nkyekyer Kobinah , Boafor Theodore 
Published: February 2007

AbstractA 2-year study involving macroscopic examination of twin placentae was conducted at the Korle Bu Teaching Hospital in Accra, Ghana to determine the proportions of the various types of twin placentation, cord insertions and number of cord vessels and their relationships. Of 765 twin-pair placentae examined, 398 (52%, 95% confidence interval [CI] 48.4%–55.6%) had fused dichorionic, 247 (32.3%, 95% CI 29.0%–35.7%) had separate dichorionic, and 119 (15.6%, 95% CI 13.1%–18.4%) had monochorionic diamniotic placentae; only one (0.1%, 95% CI 0.0%–0.8%) had monochorionic monoamniotic placentation. Of 1529 cords whose insertion could be determined, 1285 (84%) had disc, 172 (11.2%) marginal and 72 (4.7%) velamentous insertions. Only 10 (0.65%) cords had two vessels (i.e., single umbilical artery). Abnormal cord insertions (marginal and velamentous) were significantly more likely to occur in monochorionic than in dichorionic placentation (odds ratio [OR] 3.56, 95% CI 2.62–4.84), and in two-vessel than in three-vessel cords (OR 5.79, 95% CI 1.44–24.5). The prevalence of two-vessel cord in monochorionic was not significantly different from that in dichorionic placentation (OR = 0.60, 95% CI 0.10–2.67). Zygosity could be determined in 53.3% of twins from placental examination and babies' sex-pair combinations. In conclusion the most common twin placentation in Ghana is fused dichorionic. Abnormal cord insertion is more common in monochorionic than dichorionic placentation. Monoamniotic twins and single umbilical artery are less common than have been reported in other centers. Modern methods of DNA analysis are needed to establish zygosity in almost half of twin pairs.
Young Netherlands Twin Register (Y-NTR): A Longitudinal Multiple Informant Study of Problem Behavior
Authors: Bartels Meike , Beijsterveldt C. E. M. (Toos) van , Derks Eske M. , Stroet Therese M. , Polderman Tinca J. C. , Hudziak James J. , Boomsma Dorret I. 
Published: February 2007

AbstractThe Netherlands Twin Register (NTR) was established around 1987 at the Vrije Universiteit in Amsterdam, the Netherlands. The current article summarizes the longitudinal genetic analyses of maternal and paternal ratings of twins' behavior as a function of the sex of the children for the traits of aggression (AGG), attention problems (AP), anxious/depression (ANX), internalizing behavior (INT) and externalizing behavior (EXT). We found that genetic influences are the most important factor in explaining individual differences in these traits. For most phenotypes, influences of genetic factors fluctuate throughout development, with the exception of AP, for which genetic influences remain of similar magnitude. Changes in genetic influences parallel those in shared environmental influences, while nonshared environmental influences remain relatively constant. Around 10% to 20% of the variance is accounted for by parent-specific shared environment, which includes rater bias. For all phenotypes, stability throughout childhood is accounted for by genetic and shared environmental factors, while nonshared environmental influences are mainly age/measurement specific. About 15% of the phenotypic stability is accounted for by rater-specific shared environmental influences, which include rater bias. In conclusion, between ages 3 and 12 genetic factors are the most important cause of individual differences in emotional and behavioral problems.
Early Childhood Temperament and the Covariation Between Internalizing and Externalizing Behavior in School-Aged Children
Authors: Rhee Soo Hyun , Cosgrove Victoria E. , Schmitz Stephanie , Haberstick Brett C. , Corley Robin C. , Hewitt John K. 
Published: February 2007

AbstractThere is significant covariation between internalizing and externalizing behavior, although there is also evidence that internalizing behavior is a protective factor against externalizing behavior. Several researchers have posited that the examination of the relationship between temperament or personality and behavior problems may help explain these seemingly contradictory results. Specifically, negative emotionality or neuroticism has been cited as a temperament characteristic that internalizing and externalizing behavior share in common, whereas behavioral inhibition may be related only to internalizing behavior. We examined the degree to which the covariation between internalizing and externalizing behavior assessed from age 4 to 12 years can be explained by temperament characteristics assessed from age 14 to 36 months. Additionally, we assessed the extent to which this relationship is due to genetic or environmental factors, analyzing data from 225 monozygotic and 185 dizygotic twin pairs assessed by the Colorado Longitudinal Twin Study. In males, a portion of the covariation between internalizing and externalizing behavior was explained by shared environmental influences in common with emotionality and shared environmental influences in common with shyness. In females, most of the covariation between internalizing and externalizing behavior was explained by shared environmental influences in common with emotionality. A possible limitation of this study is that the covariation between temperament and behavior problems may be due to shared measurement variance, as parent ratings were used to assess both temperament and behavior problems.
The Nonshared Environment in Adolescent Development (NEAD) Project: A Longitudinal Family Study of Twins and Siblings from Adolescence to Young Adulthood
Authors: Neiderhiser Jenae M. , Reiss David , Hetherington E. Mavis 
Published: February 2007

AbstractThe Nonshared Environment in Adolescent Development (NEAD) project is a longitudinal study of twins/siblings and parents that has been assessed 3 times: middle adolescence, late adolescence and young adulthood (N = 720 families at Time 1). Siblings varied in degree of genetic relatedness including identical twins, fraternal twins, full siblings, half siblings and genetically unrelated (or step) siblings. There were also two family types: nondivorced and step. A multimeasure, multirater approach was taken in NEAD, with data collected from all participants (2 twins or siblings, mother and father) as well as from coded videotaped observations of family interactions. Detailed assessments of family relationships, adolescent adjustment and competence were collected at all 3 times. The original aim of NEAD was to identify systematic sources of nonshared environmental influences that contribute to differences among family members. Although systematic sources of nonshared environmental influences were not found in NEAD, three major sets of findings emerged: (1) genetic influences on family relationships and on associations between family relationships and adolescent adjustment; (2) genetic and environmental influences on adolescent adjustment, comorbidity and stability and change in adolescent adjustment from middle to late adolescence; and (3) genetic influences on relationships outside the family.
Twins' Early Development Study (TEDS): A Multivariate, Longitudinal Genetic Investigation of Language, Cognition and Behavior Problems from Childhood Through Adolescence
Authors: Oliver Bonamy R. , Plomin Robert 
Published: February 2007

AbstractThe Twins' Early Development Study (TEDS) is a large-scale longitudinal study of twins from early childhood through adolescence. Since its conception, TEDS has had as its focus the study of problematic development within the context of normal variation, mainly in the development of language, cognitive and academic abilities and behavior problems from multivariate quantitative and molecular genetic perspectives. TEDS twins have been assessed at 2, 3, 4, 7, 9, 10 and (currently) 12 years of age, and DNA collected from more than 12,000 children. Identified from birth records of twins born in the United Kingdom between 1994 and 1996, more than 15,000 pairs of twins originally enrolled in TEDS, and well over 13,000 pairs — representative of the UK population — remain involved in the study to date. Similar to many other twin and adoption studies, TEDS data indicate that both genetic and environmental influences are important in nearly all areas of behavioral development. Multivariate genetic analyses allow researchers to go beyond this basic nature–nurture question, and TEDS results suggest that, especially in the area of learning abilities and disabilities, genes are generalists and environments are specialists. That is, genes largely contribute to similarity in performance within and between learning abilities and disabilities and across age, whereas the environment contributes to differences in performance. Quantitative genetic findings such as these chart the course for molecular genetic research. The TEDS dataset is proving valuable in genome-wide association research that tries to identify some of the many genes responsible for the ubiquitous heritability of behavior.
Backwater Immigration by Fishes through a Water Control Structure: Implications for Connectivity and Restoration
Authors: Schultz Douglas W. , Garvey James E. , Brooks Ronald C. 
Published: March 2007

Abstract
Recent efforts to reduce sediment loading in large-river backwaters have relied on inexpensive low-maintenance structures that promote river–backwater connectivity. How these structures influence ichthyofauna is not understood. We quantified the distribution of fishes through a stop-log structure installed during the Swan Lake habitat restoration project on the lower Illinois River. Modified hoop nets were systematically fished simultaneously in a two-dimensional 3 vertical × 3 horizontal grid of net locations to capture fish as they immigrated into the lake through the structure. Catches were dominated by gizzard shad Dorosoma cepedianum and freshwater drum Aplodinotus grunniens. Adult freshwater drum, adult common carp Cyprinus carpio, and juvenile silver carp Hypophthalmichthys molitrix exhibited an affinity for the lower two-thirds of the water column. Lengths of freshwater drum increased with depth, particularly during the spring. Common carp catch rates were highest during spring, whereas those for silver carp were highest during fall and winter. Closure of the bottom two-thirds of the lower Swan Lake water control structure could reduce immigration of exotic and undesirable species into the backwater; their recruitment associated with the lake could be affected accordingly. The water control structure does not appear to have negatively affected lateral fish movement. However, habitat quality and availability probably determine seasonal patterns in backwater use. In systems where exotic species are abundant, lateral connectivity may need to be assessed from a cost-benefit perspective, specifically as it pertains to maintaining habitat availability for indigenous fishes versus limiting habitat availability for introduced species.
Biomechanical Effects of Rapid Palatal Expansion on the Craniofacial Skeleton with Cleft Palate: A Three-Dimensional Finite Element Analysis
Authors: Pan Xiaogang , Qian Yufen , Yu Jia , Wang Dongmei , Tang Yousheng , Shen Gang 
Published: March 2007

Objective: To explore the biomechanical effects of rapid palatal expansion (RPE) on the craniofacial skeleton with cleft palate. Design: A finite element model of a patient's skull with cleft lip and palate (CLP) was generated using data from spiral computed tomographic (CT) scans. Finite elemental analysis (FEA) was performed to depict the physiological changes and stress distribution in craniofacial structures loaded with orthopedic forces that created 5 mm of displacement on the region of the maxillary first premolar and first molar crown. Patients, participants: A 14-year-old girl with left complete unilateral CLP was included in this study. Interventions: Spiral CT was carried out prior to any treatment. Main outcome measure(s): Three-dimensional (3D) features of displacement and stress distribution were analyzed following application of transverse orthopedic force. Results: Marked amount of displacement and deformation occurred in the dental region. Asymmetric displacement and deformation of UCLP under RPE were evident. The stress generated by RPE was dispersed around the cleft palate and nasal cavity, and was distributed at the buttress of the maxilla-inferior border of the nasal cavity, outboard of the orbit, and central frontal bone near the nasion. Conclusions: Application of RPE to UCLP patients induces a pyramid-like displacement of the nasomaxillary complex along with fan-like expansion of the upper dental arch. The uniqueness of RPE with UCLP, however, lies in the asymmetric expansion and dispersed stress distribution around the lateral maxilla buttress and outboard of orbit.
A Randomized Control Trial Investigating the Effect of Presurgical Orthopedics on Feeding in Infants with Cleft Lip and/or Palate
Authors: Masarei A. G. , Wade A. , Mars M. , Sommerlad B. C. , Sell D. 
Published: March 2007

Objective: To investigate the controversial assertion that presurgical orthopedics (PSO) facilitate feeding in infants with cleft lip and palate. Design: Randomized control trial of 34 infants with nonsyndromic complete unilateral cleft lip and palate and 16 with cleft of the soft and at least two thirds of the hard palate. Allocation to receive presurgical orthopedics or not used minimization for parity and gender. Other aspects of care were standardized. Setting: The North Thames Regional Cleft Centre. Main Outcome Measures: Measurements were made at 3 months of age (presurgery) and at 12 months of age (postsurgery). Primary outcomes were anthropometry and oral motor skills. Objective measures of sucking also were collected at 3 months using the Great Ormond Street Measure of Infant Feeding. Twenty-one infants also had videofluoroscopic assessment. Results: At 1 year, all infants had normal oral motor skills and no clear pattern of anthropometric differences emerged. For both cleft groups, infants randomized to presurgical orthopedics were, on average, shorter. The presurgical orthopedics infants were, on average, lighter in the unilateral cleft and lip palate group, but heavier in the isolated cleft palate group. Infants with complete unilateral cleft and lip palate randomized to presurgical orthopedics had lower average body mass index (mean difference PSO-No PSO: −0.45 (95% confidence interval [−1.78, 0.88]), this trend was reversed among infants with isolated cleft palates (mean difference PSO-No PSO: 1.98 [−0.95, 4.91]). None of the differences were statistically significant at either age. Conclusions: Presurgical orthopedics did not improve feeding efficiency or general body growth within the first year in either group of infants.