bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heritability of the Second to Fourth Digit Ratio (2d:4d): A Twin Study
Authors: Paul Simon N. , Kato Bernet S. , Cherkas Lynn F. , Andrew Toby , Spector Tim D. 
Published: March 2007

AbstractThe second to fourth finger length ratio (2d:4d) has been the subject of much recent work and is thought to be related to diverse gender and hormone-related traits including sports ability, disease susceptibility, attractiveness and sexuality. It is established in utero and remains constant in adulthood. Familial clustering has been thought to contribute to the development of 2d:4d from early studies but no twin studies exploring heritability have been reported to date. In this study, a sample of 456 female twin pairs (148 monozygotic [MZ], 308 dizygotic [DZ]) aged 18 to 79 years was used to estimate the heritability of 2d:4d for the right and left hands. Finger lengths were derived from hand xrays. Variance components analysis was used to estimate and contrast genetic and environmental effects on this phenotype. The mean 2d:4d was 0.92 (SD = 0.001) for both hands. The MZ intraclass correlation was higher than in DZ (.66 vs. .35 for right 2d:4d, and .71 vs. .37 for left 2d:4d). The best fit model included additive polygenic and unique environmental effects (‘AE’ model), with no significant common environmental effects detected. Heritability was estimated to be approximately 66% for 2d:4d (95% confidence interval 0.5–0.78). These results suggest a substantial genetic contribution to the determination of this hormonally related skeletal ratio in women, which could be more influential than the effects of common prenatal environmental factors. However the current study design does not preclude the possibility of confounding between heritability estimates and unobserved prenatal effects.
Efficacy of Retrospective Recall of Attention-Deficit Hyperactivity Disorder Symptoms: A Twin Study
Authors: Schultz Mark R. , Rabi Keren , Faraone Stephen V. , Kremen William , Lyons Michael J. 
Published: March 2007

AbstractAttention-deficit hyperactivity disorder (ADHD) is currently recognized as a neurobiological, genetically based disorder in both children and adults. In this article we examine whether, by using a sample of middle-aged male twin veterans, the phenotypic characterization, prevalence, heritability and the longitudinal course of the illness is comparable to results observed in samples of children and adolescents. We evaluated the utility of adult reports of lifetime ADHD symptoms by examining the heritability of retrospectively reported childhood symptoms, using both symptom-based and discrete classification- based approaches, as well as examining the persistence of ADHD symptoms into adulthood for that subsample of individuals who were judged to possibly have ADHD as children. Our results showed prevalence rates that were approximately similar to those observed in other studies, demonstrable familiality, similar item endorsement patterns, a strong genetic association between hyperactive and inattentive subtypes, and a longitudinal decline in symptom severity. We concluded that while assessing ADHD in adult probands may be less accurate than with children or adolescents, since it demonstrates several characteristics in common with other assessment techniques it remains a viable diagnostic and research strategy, even with population samples.
Linguistic Features of Japanese Twins at 3 or 4 Years of Age Evaluated by Illinois Test of Psycholinguistic Abilities
Authors: Kobayashi Yoko , Hayakawa Kazuo , Hattori Rituko , Ito Mikiko , Kato Kenji , Hayashi Chisato , Mikami Hiroshi 
Published: March 2007

AbstractIn general, twins have delayed language development early in childhood compared with singletons. The purpose of this study was to clarify the overall linguistic features of twins. A Japanese version of the Illinois Test of Psycholinguistic Abilities (ITPA) was administered in 24 twin pairs (aged 3 to 4 years) at their own homes. The overall language abilities of the twins were in the normal range (based on ITPA normative data: mean scale score 36.0 ± 6.0 points), and for the ITPA subtests only, Auditory Reception fell within the range of language disorder (mean scale score 24.9 ± 5.1 points). The findings suggest that in 3- to 4-year-old Japanese twins, overall language abilities are not delayed. However, there may be specific difficulties with auditory reception skills.
A Note on the Asymptotic Distribution of Likelihood Ratio Tests to Test Variance Components
Authors: Visscher Peter M. 
Published: March 2007

AbstractWhen using maximum likelihood methods to estimate genetic and environmental components of (co)variance, it is common to test hypotheses using likelihood ratio tests, since such tests have desirable asymptotic properties. In particular, the standard likelihood ratio test statistic is assumed asymptotically to follow a χ2distribution with degrees of freedom equal to the number of parameters tested. Using the relationship between least squares and maximum likelihood estimators for balanced designs, it is shown why the asymptotic distribution of the likelihood ratio test for variance components does not follow a χ2distribution with degrees of freedom equal to the number of parameters tested when the null hypothesis is true. Instead, the distribution of the likelihood ratio test is a mixture of χ2distributions with different degrees of freedom. Implications for testing variance components in twin designs and for quantitative trait loci mapping are discussed. The appropriate distribution of the likelihood ratio test statistic should be used in hypothesis testing and model selection.
High Microsatellite and SNP Genotyping Success Rates Established in a Large Number of Genomic DNA Samples Extracted From Mouth Swabs and Genotypes
Authors: Min Josine L. , Lakenberg Nico , Bakker-Verweij Margreet , Suchiman Eka , Boomsma Dorret I. , Slagboom P. Eline , Meulenbelt Ingrid 
Published: March 2007

AbstractIn this article, we present the genomic DNA yield and the microsatellite and single nucleotide polymorphism (SNP) genotyping success rates of genomic DNA extracted from a large number of mouth swab samples. In total, the median yield and quality was determined in 714 individuals and the success rates in 378,480 genotypings of 915 individuals. The median yield of genomic DNA per mouth swab was 4.1 μg (range 0.1–42.2 μg) and was not reduced when mouth swabs were stored for at least 21 months prior to extraction. A maximum of 20 mouth swabs is collected per participant. Mouth swab samples showed in, respectively, 89% for 390 microsatellites and 99% for 24 SNPs a genotyping success rate higher than 75%. A very low success rate of genotyping (0%–10%) was obtained for 3.2% of the 915 mouth swab samples using microsatellite markers. Only 0.005% of the mouth swab samples showed a geno-typing success rate lower than 75% (range 58%–71%) using SNPs. Our results show that mouth swabs can be easily collected, stored by our conditions for months prior to DNA extraction and result in high yield and high-quality DNA appropriate for genotyping with high success rate including whole genome searches using microsatellites or SNPs.
Familial Risks for Diseases of Myoneural Junction and Muscle in Siblings Based on Hospitalizations and Deaths in Sweden
Authors: Hemminki Kari , Li Xinjun , Sundquist Kristina 
Published: March 2007

AbstractDiseases of the myoneural junction and muscle are disabling and some are life-threatening. Recent successes in the identification of the underlying genetic mechanisms have had profound implication for their diagnostics, treatment and classification. We define familial risks for siblings who were hospitalized for or deceased from diseases of the myoneural junction and muscle. A nationwide database on diseases of the myoneural junction and muscle was constructed by linking the Multigeneration Register on 0- to 69-year-old siblings to the Hospital Discharge Register and the Causes of Death Register from years 1987 to 2001. Standardized risk ratios (SIRs) were calculated for affected sibling pairs by comparing to those whose siblings had no diseases of myoneural junction and muscle. Among a total of 2307 patients, myasthenia gravis, muscular dystrophy and myotonic disorders were commonest diagnoses. The sibling risks for these disease were 22, 190 and 198, respectively, when a sibling was diagnosed with any disease of the myoneural junction and muscle. The concordant SIRs, both siblings presenting the same disease, were 42 for myasthenia gravis, 737 for muscular dystrophy, 2000 for congenital myopathy, 1211 for myotonic disorder, 909 for periodic paralysis and 209 for unspecified myopathy. Only a few discordant sibling pairs were noted. The very high overall SIRs for the diseases of the myoneural junction and muscle imply that the sporadic forms of these diseases are relatively rare and these diseases are overwhelmingly heritable.
Genetic Influences on Free and Cued Recall in Long-Term Memory Tasks
Authors: Volk Heather E. , McDermott Kathleen B. , Roediger Henry L. , Todd Richard D. 
Published: March 2007

AbstractLong-term memory (LTM) problems are associated with many psychiatric and neurological illnesses and are commonly measured using free and cued recall tasks. Although LTM has been linked with biologic mechanisms, the etiology of distinct LTM tasks is unknown. We studied LTM in 95 healthy female twin pairs identified through birth records in the state of Missouri. Performance on tasks of free recall of unrelated words, free and cued recall of categorized words, and the vocabulary section of the Wechsler Adult Intelligence Scale (WAIS-R) were examined using structural equation modeling. Additive genetic and unique environmental factors influenced LTM and intelligence. Free recall of unrelated and categorized words, and cued recall of categorized words, were moderately heritable (55%, 38%, and 37%). WAIS-R vocabulary score was highly heritable (77%). Controlling for verbal intelligence in multivariate analyses of recall, two components of genetic influence on LTM were found; one for all three recall scores and one for free and cued categorized word recall. Recall of unrelated and categorized words is influenced by different genetic and environmental factors indicating heterogeneity in LTM. Verbal intelligence is etiologically different from LTM indicating that these two abilities utilize different brain functions.
Sex Differences in Symptoms of Depression in Unrelated Individuals and Opposite-Sex Twin and Sibling Pairs
Authors: Middeldorp Christel M. , Wray Naomi R. , Andrews Gavin , Martin Nicholas G. , Boomsma Dorret I. 
Published: March 2007

AbstractDiagnosis of a major depressive episode by theDiagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Associationrequires 5 out of 9 symptoms to be present. Therefore, individuals may differ in the specific symptoms they experience and reach a diagnosis of depression via different pathways. It has been suggested that depressed women more often report symptoms of sleep disturbance, appetite or weight disturbance, fatigue, feelings of guilt/worthlessness and psychomotor retardation than depressed men. In the current study, we investigate whether depressed men and women differ in the symptoms they report. Two samples were selected from a sample of Dutch and Australian twins and siblings. First, Dutch and Australian unrelated depressed individuals were selected. Second, a matched epidemiological sample was created consisting of opposite-sex twin and sibling pairs in which both members were depressed. No sex differences in prevalence rates for symptoms were found, with the exception of decreased weight in women in the sample of unrelated individuals. In general, the similarities in symptoms seem to far outweigh the differences in symptoms between men and women. This signifies that men and women are alike in their symptom profiles for major depression and genes for depression are probably expressed in the same way in the two sexes.
Stillbirths in Multiple Births: Test of Independence
Authors: Fellman Johan , Eriksson Aldur W. 
Published: March 2007

AbstractThe stillbirth rate in twins is a more sensitive indicator of environmental hazards than the stillbirth rate in singletons. Medical care or other socioeconomic factors may be more influential for perinatal survival in twin than in single deliveries. Studies have indicated that stillbirths among children in a set of multiple maternities are not independent. Models were considered assuming independent outcomes within a set of multiple maternities. Analyses of the stillbirth rates confirm that the risk of stillbirth among males is almost constantly higher than among females. Any model introduced should assume different stillbirth rates for males and females. The models were tested with both maximum likelihood and minimum χ2 methods. Data was analyzed from Sweden, the Åland Islands, Saxony, England and Wales, and significant discrepancies obtained from the independence models. The same-sexed twin data contain both monozygotic and dizygotic twin sets with apparently different stillbirth rates. Consequently, for same-sexed twins the proposed model could be considered too simple. After improvement by splitting the same-sexed data into monozygotic and dizygotic twin sets, the dependence still remains. The proportion of both same-sexed and opposite-sexed twin pairs that contain two stillborn is greater than what the stillbirth rates and the independence should indicate. Consequently, stillbirth rate estimates based on the relative frequency of twin sets with two stillborn children have a positive bias. When the stillbirth rate decreases, the number of sets with two stillborn children decreases more slowly than would be indicated by independence.
HealthTwiSt: The Berlin Twin Registry
Authors: Busjahn Andreas 
Published: March 2007

AbstractThe Berlin Twin Registry began as a short-term local project and developed into a resource that now serves partners throughout Germany and Europe. A twin registry as a private company is a different approach with pros and cons. Compared to academic institutions, there are greater flexibilities in collaborations, as well as acquisition and use of research funds. Recruitment is based on invitation in the context of the mass media coverage of scientific results. Phenotyping in normal twin subjects is concentrated on intermediate phenotypes that can bear on common diseases. These phenotypes include proteomic approaches and gene expression. Some results are briefly described to give an impression of the range of research topics and related opportunities for retrospective and prospective collaborative research.
CoSMoS and TwinPaW: Initial Report on Two New German Twin Studies
Authors: Spinath Frank M. , Wolf Heike 
Published: March 2007

AbstractAfter briefly recapitulating two earlier German twin studies (BiLSAT and GOSAT), we present two new German twin studies with a longitudinal perspective: CoSMoS and TwinPaW. The twin study on Cognitive ability, Self-reported Motivation and School performance (CoSMoS) aims to investigate predictors and influences of school performance in a genetically sensitive design, beginning with children in late elementary school. The Twin study on Personality And Wellbeing (TwinPaW) focuses on adult personality and its relation to physical health as well as health-related behavior in an adult sample of twins. Both studies are characterized by an effort to recruit new large twin samples through a novel recruitment procedure aimed at reducing self-selective sampling. In two German federal states, contact information on persons born on the same day and with the same name was retrieved from record sections. From the resulting pool of more than 36,000 addresses we contacted approximately 2000 parents of twins aged 9 and 10 for CoSMoS, as well as 2000 adult twin pairs for TwinPaW by telephone and mail. Personal contact by telephone proved to be more efficient with agreement rates of 63% in the children sample and 65% in the adult sample. In this article we briefly describe the rationale and the study aims of CoSMoS and TwinPaW as well as the characteristics of the sample we have recruited so far.
The Osaka University Aged Twin Registry: Epigenetics and Identical Twins Discordant for Aging-Dependent Diseases
Authors: Hayakawa Kazuo , Kato Kenji , Onoi Miyuki , Yang-Ping Cai , Kanamori Masao , Doi Syuichi , Hayashi Chisato , Kikuchi Hiroyuki , Nishihara Reiko , Kadota Kensuke 
Published: March 2007

AbstractThe Osaka University Aged Twin Registry (OUATR) is the largest adult twin registry in Japan. Since its establishment in 1974, the OUATR has conducted a number of studies with particular focus on the environmental contribution to physical–cognitive–mental aging, longevity and aging-dependent diseases in later adulthood. The registry consists of 12,000 pairs of Japanese twins born between 1900 and 1935. Two hundred and fifty pairs of twins have undergone comprehensive medical examination to date. Follow-up questionnaires have been mailed out on a regular basis, for the purpose of checking current vital statuses, health conditions, and so forth. The main objective of this longitudinal twin study is to contribute to the prevention of lifestyle-related diseases and the promotion of successful aging.
Twin Database of the Secondary School Attached to the Faculty of Education of the University of Tokyo
Authors: Ooki Syuichi , Asaka Akio 
Published: March 2007

AbstractThis article profiles the historical twin databases of the secondary education school attached to the Faculty of Education at the University of Tokyo. The school was established in 1948. Every year, about 50 pairs of twins of all sex and zygosity combinations and aged 11 to 12 years take an examination, and about 10 to 20 pairs are admitted based on the results. Three independent datasets exist: one for applicants (11–12 years), one for students (12–18 years), and one for graduates (18–72 years). These three historical databases and research perspectives are introduced herein.
Population-Based Database of Multiples in Childhood of Ishikawa Prefecture, Japan
Authors: Ooki Syuichi 
Published: March 2007

AbstractA new type of population-based database of multiples in childhood at the prefecture level was initiated in 2004 in Ishikawa Prefecture, Japan. We conducted an exhaustive search for demographic information concerning families with multiples, family support provided by governmental and medical institutions by mailed questionnaire, and at the same time tried to organize a human network to support such families. This registry aims not only to aid research on human genetics and maternal and child health, but also to contribute to the development of welfare programs for families with multiples.
Update on the NAS-NRC Twin Registry
Authors: Page William F. 
Published: March 2007

AbstractThe National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry is one of the oldest, national population-based twin registries in the United States. It consists of 15,924 white male twin pairs born in the years 1917 to 1927 (inclusive), both of whom served in the armed forces, mostly during World War II. This article updates activity in this registry since the earlier 2002 article in Twin Research. The results of clinically based studies on dementia, Parkinson's disease, age-related macular degeneration, and primary osteoarthritis were published, as well as articles based on previously collected questionnaire data on chronic fatigue syndrome, functional limitations, and healthy aging. In addition, risk factor studies are being planned to merge clinical data with earlier collected risk factor data from questionnaires. Examination data from the subset of National Heart, Lung, and Blood Institute (NHLBI) twins resulted in a number of articles, including the relationship of endogenous sex hormones to coronary heart disease and morphological changes in aging brain structures. The NEO Five-Factor Personality Inventory (a paper-and-pencil self-administered questionnaire) has been fielded for the first time. A push to consolidate the various data holdings of the registry is being made.
PennTwins: A Population-Based Cohort for Twin Studies
Authors: Coccaro Emil F. , Jacobson Kristen C. 
Published: March 2007

AbstractThe current article describes the creation and composition of the PennTwins Cohort and provides details on the demographic characteristics of the sample. The PennTwins Cohort was developed using a population-based method of ascertainment and currently has 9401 28- to 47-year-old twins, including 2225 confirmed twin pairs and 4951 twins whose co-twins have not yet registered. Zygosity data have been used to identify 919 monozygotic, 634 same-sex dizygotic, and 445 opposite-sex dizygotic pairs. GeoCode data on gender, age, and certain demographic characteristics were obtained for the addresses of all twins who were mailed invitations to be part of the cohort. Analysis of the available data show only very small differences between twins who are currently part of the PennTwins Cohort and potential twins who either did not respond to recruitment or who could not be located. Similarly, only very small demographic differences exist between twins from complete pairs and twins whose co-twins are not yet registered, and there are no differences across zygosity. Thus, despite a relatively low overall response rate (12% of all twins born in Pennsylvania from 1959–1978), there is no evidence that the sample differs in any meaningful respect from the larger population.
Characterization of thin water layers in pulp by tritium exchange. Part 2: Effect of refining on water absorption
Authors: Walsh Frances L. , Banerjee Sujit 
Published: March 2007

Abstract
The surface area of pulp increases upon refining, which also increases the quantity of bound water. The subfraction of water attached to the surface as a monolayer can be determined by adding tritiated water to a pulp/water suspension and measuring the distribution of tritium between the pulp and bulk water. For bleached kraft pulp the tightly bound water slowly increases with progressive refining, increases sharply at 360 ml Canadian Standard Freeness (CSF), and then falls below CSF 220 ml. The fiber saturation point displays a similar profile, although the changes are much less pronounced. It is proposed that refining occurs in three discrete stages. First, refining down to CSF 360 ml removes the primary cell wall and S1 layer, while the S2 layer begins to swell. Next, internal delamination occurs within the S2 layer between CSF 360 and 220 ml, as confirmed by scanning electron microscopy. The onset of delamination is sudden: dramatic changes in fiber structure occur at CSF 360 ml, at which point the tightly bound water content rapidly increases. Finally, fiber destruction occurs below CSF 220 ml.
Development of an accelerated soil-contact decay test
Authors: Li Gan , Nicholas Darrel D. , Schultz Tor P. 
Published: March 2007

Abstract
An accelerated method to evaluate wood preservatives for soil contact was explored using thin (4 mm) pine sticks in small decay cups containing non-sterile soil and wood compost-amended soil. The extent of wood decay was measured by monitoring changes in the bending elasticity (MOE) of the test samples, which was found to be a sensitive measure of the decay extent for both chromated copper arsenate (CCA)- and copper naphthenate (CuNap)-treated wood, and untreated wood. The decay rate was rapid, with significant decay detected in untreated wood after only 2 months of exposure. Decay in both treated and untreated wood samples was observed sooner when the soil was amended with wood compost. The compost-amended soil also gave significantly higher copper depletion for CCA- but not CuNap-treated wood. Although the results from this test should not be extrapolated to predict field test performance, it does appear to be applicable for rapid comparison of the performance of new and established preservative systems.