Assessment of the hereditary and environmental influence on the growth of hand bones in twin children]

Forty pairs of twins from 6 to 15 years of age were subjected to two rentgenographies of the right hand. The degree of similarity between the twins of one pair was studied by the value of the absolute and relative increase of sizes of the hand phalanges. Zygotes, sex and age of children were taken into account. The effect of hereditary factors on the growth of hand phalanges in boys is pronounced better than in girls. In the formers the degree of similarity between the twins of one pair is lower than in the latters. In 12-15 years of age such similarity is higher than in 8-11 years old twins.     

Skeletal maturity and bone growth in twins

Heritability of skeletal maturity and bone growth is discussed on the basis of intrapair resemblances (correlation coefficients) and differences (revised percent deviations) in mono- and dizygotic twins and random pairs of unrelated children. A series of 1072 radiographs of the right hand and wrist in 63 male and 70 female pairs of monozygotic twins, and 25 male and 21 female pairs of dizygotic twins aged 12 to 18 years studied longitudinally in Tokyo were used. Skeletal maturity based on the TW2 age suggests higher heritability than bone growth based on the second metacarpal dimensions. In the latter, length has higher heritability than width and cortical thickness. A dosage effect seems to be suggested in width and some indices in the second metacarpal, but is not confirmed in skeletal maturation.     

Genetic and environmental influences on Anxious/Depression during childhood: a study from the Netherlands Twin Register

For a large sample of twin pairs from the Netherlands Twins Register who were recruited at birth and followed through childhood, we obtained parental ratings of Anxious/Depression (A/D). Maternal ratings were obtained at ages 3 years (for 9025 twin pairs), 5 years (9222 pairs), 7 years (7331 pairs), 10 years (4430 pairs) and 12 years (2363 pairs). For 60-90% of the pairs, father ratings were also available. Multivariate genetic models were used to test for rater-independent and rater-specific assessments of A/D and to determine the genetic and environmental influences on individual differences in A/D at different ages. At all ages, monozygotic twins resembled each other more closely for A/D than dizygotic twins, implying genetic influences on variation in A/D. Opposite sex twin pairs resembled each other to same extent as same-sex dizygotic twins, suggesting that the same genes are expressed in boys and girls. Heritability estimates for rater-independent A/D were high in 3-year olds (76%) and decreased in size as children grew up [60% at age 5, 67% at age 7, 53% at age 10 (60% in boys) and 48% at age 12 years]. The decrease in genetic influences was accompanied by an increase in the influence of the shared family environment [absent at ages 3 and 7, 16% at age 5, 20% at age 10 (5% in boys) and 18% at age 12 years]. The agreement between parental A/D ratings was between 0.5 and 0.7, with somewhat higher correlations for the youngest group. Disagreement in ratings between the parents was not merely the result of unreliability or rater bias. Both the parents provided unique information from their own perspective on the behavior of their children. Significant influences of genetic and shared environmental factors were found for the unique parental views. At all ages, the contribution of shared environmental factors to variation in rater-specific views was higher for father ratings. Also, at all ages except age 12, the heritability estimates for the rater-specific phenotype were higher for mother ratings (59% at age 3 and decreasing to 27% at age 12 years) than for father ratings (between 14 and 29%). Differences between children, even as young as 3 years, in A/D are to a large extent due to genetic differences. As children grow up, the variation in A/D is due in equal parts to genetic and environmental influences. Anxious/Depression, unlike many other common childhood psychopathologies, is influenced by the shared family environment. These findings may provide support for why certain family therapeutic approaches are effective in the A/D spectrum of illnesses.     

Development of the female mammary gland at young ages (morphometric data)

By means of a developed method of histotopographical sections cartograms, 146 preparations obtained from female persons at the age of 8-25 years have been studied. The organ is intensively developing not only at 12-16 years of age, but at 22-25 years, as well. A close correlation is noted at 10-11 years of age between the mammary gland mass and the degree of its parenchyma (glandular tree) development. Subsequently, the connection between these indices becomes essentially weaker. At the age of 15-25 years, according to the variability and standard deviation quantile classes reflecting stages in the organ formation (the degree of the glandular tree development), five types of the mammary gland are distinguished: weak, low middle, middle, high middle and high. During transition of the mammary gland from the weak to the high type, at first the glandular tree is intensively developing in the periphery and in the internal parts, and then in the external squares and in the center of the organ. The degree of uneven development in the glandular tree increases when the middle type is reached. Subsequently, it decreases up to the initial level.     

The Role of the Genotype in the Development of the Neurophysiological Mechanisms Involved in the Spatial Integration of Neocortex Bioelectric Activity

The contribution of genetic factors into the formation of the neurophysiological mechanisms determining the systemic organization of cortical activity has been estimated in 12 pairs of monozygotic (MZ) and 5 pairs of dizygotic (DZ) twins (18–25 years of age). The similarity of individual patterns of the spatial interaction of cortical bioelectric activity measured for different combinations of EEG statistical relationships from 16 monopolar leads has been estimated in each pair of twins and in each of the 544 pairs of unrelated subjects in both groups. The results of the study suggest a high population invariance and small genetic and phenotypic variations of the morphofunctional systems constituting the main neurophysiological mechanisms of general cerebral integration. Brainstem and subcortical regulatory structures play the leading role in the integration of different brain regions into an organized system. Apparently, the formation of these structures during ontogeny follows the same general pattern in all individuals, because deviation from it is likely to affect the fundamental monomorphic characters of the species. The formation of neocortical interregional connections may be expected to exhibit greater individual variation, with the roles of hereditary and environmental factors in the formation of long and relatively short intercortical interactions being different. Apparently, the individual variation of the long intra- and interhemispheric fiber pathways forming the specific morphological framework of the neocortex is largely determined by the genotype. However, the intercentral interactions mediated by short corticocortical connections that are formed in the course of the vital activity of an individual are likely to be mainly determined by the external and internal environments.     

大熊猫双胞胎生长发育影响因素的研究

为了研究影响大熊猫Ailuropoda melanoleuca双胞胎生长发育的因素,以2013—2016年成都大熊猫繁育研究基地出生的22对大熊猫双胞胎幼仔及其母兽为研究对象,分析母兽孕期增重、双胞胎个体性别和双胞胎性别类型与大熊猫双胞胎幼仔初生体质量之间的关系,以及双胞胎个体性别和大熊猫幼仔初生体质量与1~12月龄大熊猫幼仔体质量之间的关系。结果显示,不同双胞胎性别类型的大熊猫幼仔初生体质量的差异有统计学意义(P=0.015),但母兽孕期增重、双胞胎个体性别与幼仔初生体质量的差异无统计学意义(P=0.257、P=0.170);双胞胎2只个体的初生体质量不同(χ^2=9.043,P=0.041),且双胞胎性别类型与幼仔初生体质量差异程度呈中等强度相关(Cramer s V=0.492,P=0.030),双雌性双胞胎初生体质量差异为20%~40%(调整后标化残差:2.30),双雄性双胞胎初生体质量差异小于20%(调整后标化残差:2.60);双胞胎个体性别和初生体质量对1~12月龄大熊猫幼仔生长发育的影响无统计学意义(P>0.05)。对大熊猫双胞胎幼仔生长发育影响因素的研究,为大熊猫双胞胎的饲养管理提供理论依据。     

The role of the genotype in the variability of human evoked potentials at different stages of ontogeny]

The determinants of individual differences in visual EPs to stimuli of different type depending on the age of subjects were studied. EPs to flash, checkerboard pattern and some other stimuli with semantic aspect were recorded in three groups of MZ, DZ twins aged 8-9, 10-12, 18-25 years. The heritability of EPs parameters is not ontogenetically stable characteristic. It changes from one age group to another in different way for separate EPs components and parameters depending on their nature, type of stimulus, area of recording. Most of all genotypical influences are manifested in EPs parameters of 10-12 years old subjects, especially the middle latency components from vertex area and latent periods of EPs in comparison with their amplitudes.     

Speech in same- and different-sex twins 4 and 5 years old.

The purpose of this study was to examine the impact of the sex makeup of pairs of twins on language acquisition. Past research indicated that this variable plays a role in speech problems of twin children. The questions raised were whether being a boy or a girl and having a boy or girl co-twin affected linguistic performance. A language test was given to 30 pairs of boy-girl twins, 16 pairs of boy twins, and 16 pairs of girl twins whose average age was 4 years 8 months. Their test scores confirmed our hypotheses. The poorest performance was obtained by the boy twin pairs and the best performance, by either the girl twin pairs or the different-sex pairs. The results were interpreted in the light of findings on language learning differences between girls and boys, and also in terms of Vygotsky's zone of proximal development.     

X-ray anatomic features of the skeletons of twin children

The size of right and left middle phalanges in the II-V fingers and the III finger have been studied in 108 pairs of monozygotic and dizygotic twins at 8--19 years of age and in 60 paris (pedagogical experiment) of separated twins (from the same pair), schoolchildren of the 2d--5th forms trained according different programs of physical culture. A great similarity of osteometric signs has been stated in monozygotic twins. As to local (intradigital) differences, a prevalence of the IIId finger should be mentioned. Maximum of genetic determination is evident for transversal growth--under high mechanical loadings on the bones, for longitudinal--under low mechanical loadings. The data of the pedagogical experiment demonstrate that increased mechanical loading on the hand bones activates osteogenesis. According to the majority of indices the main is the "radial" (II--III fingers) type.     

Mortality among twins after age 6: fetal origins hypothesis versus twin method.

OBJECTIVE--To test the validity of the fetal origins hypothesis and the classic twin method. DESIGN--Follow up study of pairs of same sex twins in which both twins survived to age 6. SETTING--Denmark. SUBJECTS--8495 twin individuals born 1870-1900, followed through to 31 December 1991. MAIN OUTCOME MEASURES--Mortality calculated on a cohort basis. RESULTS--Mortality among twins and the general population was not significantly different except among females aged 60-89, in whom mortality among twins was 1.14 times (SE 0.03) higher than in the general population. Mortality among female dizygotic twins was 1.77 times (0.18) higher than among monozygotic twins at age 30-59. Otherwise, mortality for monozygotic and dizygotic twins did not consistently differ after age 6. CONCLUSION--According to the fetal origins hypothesis the risk of adult morbidity and mortality is heightened by retardation in intrauterine growth. Twins, and in particular monozygotic twins, experience growth retardation in utero. The findings in the present study suggest that the fetal origins hypothesis is not true for the retardation in intrauterine growth experienced by twins. Furthermore, the data are inconsistent with the underlying assumption of a recent claim that the classic twin method is invalid for studies of adult diseases. The present study is, however, based on the one third of all pairs of twins in which both twins survived to age 6. The possible impact of this selection can be evaluated in future studies of cohorts of younger twins with lower perinatal and infant mortality.     

Effects of Heritability,Shared Environment,and Nonshared Intrauterine Conditions on Child and Adolescent BMI

Heritability studies of BMI, based upon twin samples, have identified genetic and shared environmental components of BMI, but have been largely silent about the nonshared environmental factors. Intrauterine factors have been identified as having significant long‐term effects on BMI and may be a critical source of nonshared environmental influence. Extant studies based on samples of either unrelated individuals or twins cannot separate the effects of genetics, shared environments, and nonshared intrauterine conditions because the one lacks variation in the degree of relatedness and the other has insufficient variation in intrauterine conditions. This study improves upon these prior studies by using a large, sibling‐based sample to examine heritability, shared environmental, and nonshared intrauterine influences on BMI during two age periods in childhood (6–8 years; 12–14 years). The primary interest was in determining the effects of the intrauterine environment on BMI as a component of the nonshared environment and in determining whether there were sex‐specific differences in heritability and/or in the intrauterine factors. These were estimated using regression‐based techniques introduced by DeFries and Fulker. Heritability of BMI was estimated to be 0.20–0.28 at 6–8 years and 0.46–0.61 at 12–14 years. Differences in heritability were found at 12–14 years between same‐sex as compared to mixed‐sex pairs. The shared environmental effect was significant at 6–8 years but insignificant at 12–14 years. Differences in birth weight were significant in all groups at 6–8 years suggesting long‐term effects of the nonshared intrauterine environment; at 12–14 years, birth weight was no longer significant for girls.     

Twin concordance for a binary trait. II. Nested analysis of ever-smoking and ex-smoking traits and unnested analysis of a "committed-smoking" trait

Twin concordance rates for a binary trait can provide information about causes of trait variation. However, if trait prevalence varies with age (or birth cohort) or between the sexes, trait concordance rates will be artificially inflated because of the matching within pairs of twins. Our previous paper showed how to minimize the effects of such confounding by using logistic regression to model trait prevalence as a function of age and sex and that the binary correlation coefficient was useful as a measure of concordance that can be adjusted for trait prevalence. This method is extended here to allow for nested analyses and is applied to the smoking habits of a sample of 3,807 pairs of adult twins. For monozygotic (MZ) twins, the correlation coefficients for the binary trait of "ever-smoking" (males: .50 +/- .04; females: .60 +/- .02) were significantly greater than for dizygotic (DZ) twins (males: .37 +/- .05; females: .31 +/- .04; unlike-sex pairs: .21 +/- .03). For "giving-up smoking," given that both twins were previously smokers, the correlations for MZ twins (males: .37 +/- .07; females: .29 +/- .05) were also greater than for DZ twins (males: .11 +/- .09; females: .26 +/- .08; unlike-sex pairs: .13 +/- .06), although the difference was not statistically significant for females. Current smokers who had been smoking for at least 10 years were arbitrarily defined as "committed-smokers." The binary trait of "committed-smoking" was more strongly correlated in MZ twins (males: .41 +/- .06; females: .41 +/- .04) than in DZ twins (males: .22 +/- .08; females: .18 +/- .05; unlike-sex pairs: .16 +/- .05). These observations suggest that as well as depending on socially determined environmental factors, smoking behavior is influenced by genetic factors and/or by environmental factors unique to the MZ twin environment, which are of particular importance as determinants of "committed-smoking." There is a need for further research to investigate the personal characteristics of "committed-smokers" and to seek intervention strategies that are more suited to the needs of individual smokers.     

Possible cytogenetic mechanisms of direct paternal influence on the human twinning tendency and their consequences: a hypothesis

Certain cytogenetic mechanisms are suggested to explain the puzzling cases of the direct male influence on the repeated twin births in mammals including humans. The hypothesis is based on the peculiarities of female oogenesis and meiosis, the peculiarities of fertilization and on the established facts of the occurrence of true viable chimaeras produced by separate fertilization of two meiotic products of oogenesis. We postulate that definite genetic factors are transferred from the paternal side whose products become active in male gametes and promote penetration of two spermatozoa (polyspermy) or appearance of two male pronuclei in the egg cytoplasm. The results of such events may be twinning and occurrence of chimaeric or heteroploid individuals. The appearance of viable twins produced by male-dependent polyspermy may be considered as a fortunate outcome of various possible cytogenetic anomalies of fertilization, meiosis, and cleavage divisions. The existence of non-canonical cases of twins, except mono-and dizygotic ones is postulated, according to the hypothesis. Twins pairs produced by two paternal and one maternal genomes may be called "one and halfzygotic or sesquizygotic". The different types of twins may be classified in an order, according to the degree of genetic similarity; monozygotic, chimaeric, sesquizygotic chimaeric, sesquizygotic and dizygotic. This gives an opportunity to explain the appearance of 2 to 3% of "doubtful cases" in mass classification of twin pairs into mono- and dizygotic. The verification of the hypothesis involves the special thorough genetic and cytogenetic analysis of all twin sibs and their parents in families with the direct paternal influence on twin births.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of motor function of the hand in aged rhesus monkeys

In the elderly, intact motor functions of the upper extremity are critical for the completion of activities of daily living. Many studies have provided insight into age-related changes in motor function. However, the precise nature and extent of motor impairments of the upper extremity remains unclear. In the current study we have modified two tasks to assess hand/digit function in both young and aged rhesus monkeys. We tested monkeys from 9 to 26 years of age on these tasks to determine the level of fine motor performance across the adult age range. Compared to young monkeys (9–12 years of age), aged monkeys (15–26 years of age) were mildly impaired on fine motor control of the digits. These findings are consistent with previous studies that have found age-related impairment in fine motor function. However, the magnitude and extent of impairment in the current study does differ from previous findings and is likely due to methodological differences in the degree of task complexity.     

Twins and the paradox of dental-age estimations: A caution for researchers and clinicians

The biological age difference among twins is frequently an issue in studies of genetic influence on various dental features, particularly dental development. The timing of dental development is a crucial issue also for many clinicians and researchers. The aim of this study was therefore to verify within groups of twins how dental development differs, by applying Demirjian's method, Mincer's charts of development of third molars and two of Cameriere's methods for dental age estimation, which are among the most popular methods both in the clinical and the forensic scenario. The sample consisted of 64 twin pairs: 21 monozygotic, 30 dizygotic same-sex and 13 dizygotic opposite-sex with an age range between 5.8 and 22.6 years. Dental age was determined from radiographs using the mentioned methods. Results showed that dental age of monozygotic twins is not identical even if they share all their genes. The mean intra-pair difference of monozygotic pairs was low and similar to the difference in dizygotic same-sex twins; the maximum difference between monozygotic twins, however, was surprisingly large (nearly two years). This should lead to some circumspection in the interpretation of systematic estimations of dental age both in the clinical and forensic scenario.     

Genetic and environmental influences on expression of recurrent headache as a function of the reporting age in twins.

To explore age-related mechanisms in the expression of recurrent headache, we evaluated whether genetic and environmental influences are a function of the reporting age using questionnaire information that was gathered in 1973 for 15- to 47-year-old Swedish twins (n = 12,606 twin pairs). Liability to mixed headache (mild migraine and tension-type headache) was explained by non-additive genetic influences (49%) in men aged from 15 to 30 years and additive genetic plus shared environmental influences (28%) in men aged from 31 to 47 years. In women, the explained proportion of variance, which was mainly due to additive genetic effects, ranged from 61% in adolescent twins to 12% in twins aged from 41 to 47 years, whereas individual specific environmental variance was significantly lower in twins aged from 15 to 20 years than in twins aged from 21 to 30 years. Liability to migrainous headache (more severe migraine) was explained by non-additive genetic influences in men, 32% in young men and 45% in old men, while total phenotypic variance was significantly lower in young men than in old men. In women, the explained proportion of variance ranged from 91% in the youngest age group to 37% in the oldest age group, with major contributions from non-additive effects in young and old women (15-20 years and 41-47 years, respectively) and additive genetic effects in intermediate age groups (21-40 years). While total variance showed a positive age trend, genetic variance tended to be stable across age groups, whereas individual specific environmental variance was significantly lower in adolescent women as compared to older women.     

Genetic determination of the neurophysiological mechanisms of the cortico-subcortical integration of bioelectrical activity of the brain

Contribution of genetical factors to neurophysiological mechanisms of cortico-subcortical integration was investigated in 12 pairs of the monozygotic and 5 pairs of dizygotic twins (aged from 18 to 25). In each pair of twins as well as in all 544 unrelated pairs of subjects from both groups, interpairs similarity of the character of the spatial interaction of bioelectrical activity of the neocortex for different combinations of statistical correlations of EEG (from 16 monopolar electrodes) was estimated. The data obtained allow to suggest a higher common population invariance and a relatively small hereditary and phenotypic variability of morphofunctional systems, which underlie neurophysiological mechanisms of the brain integration in general. Apparently, the formation of the brain stem and subcortical regulatory structures in the ontogenesis, the structures that play the main role in the realization of system combination of different parts of the brain into united formation, occurs to all individuals according to a single principle since its disturbance can probably affect the fundamental monomorphal features of the species. In turn, one can expect a great interindividual variability of establishing of the intraregional connections of neocortex, the role of genetic and environmental factors in the formation of short and relatively long interactions being complex.     

Masculinization of the eruption pattern of permanent mandibular canines in opposite sex twin girls

The aim of this study is to explore the effect of prenatal androgenization on the clinical eruption of permanent teeth expressing dimorphism and bimaturism. The eruption curves of permanent teeth (except third molars), including those that make up the canine complex (permanent canines, lower first premolars), are compared among opposite sex twins (OS twins) relative to single‐born boys and girls. The comparisons are made with regard to three phases of eruption (pierced mucosa, half‐ erupted, and completely erupted) from a cross‐sectional sample of dental casts, using Kaplan–Meier survival and Cox regression analyzes. The casts were collected from 2159 school children from the US Collaborative Perinatal Project, including 39 pairs of OS‐twins, of which 12 pairs (30.8%) were Euro‐Americans and 27 pairs (69.2%) were of African‐American ancestry. The eruption patterns of the incisors, upper first molars, and lower canines were found to be significantly masculinized (delayed) among OS twin girls. The differences in most other teeth were either not significant, or the number of observations of active eruption phases were too few, such as in the upper first molars and incisors, to yield strong evidence and meaningful results. The masculinization of the tooth eruption pattern in OS twin girls is intriguing because of the lower canine responses during puberty, as well as canine primordial formation during early fetal androgenization of their co‐twin during the 8th to 14th gestational weeks. The present results offer a challenge for future research exploring tooth eruption mechanisms, and may also highlight some cases of delayed or ectopic canines, which are biased toward females. Am J Phys Anthropol 151:566–572, 2013. © 2013 Wiley Periodicals, Inc.     

Contribution of hereditary factors to the variability of growth at different stages of individual development (twin studies)

A study of monozygotic and dizygotic twins from the moment of their birth till 13 years of age showed that differences in twin genesis and conditions of prenatal development exert no statistically significant influence on formation of average indices. At different stages of ontogenesis contribution of the genetic determinant estimated by index H was different as to a degree of manifestation, directivity (+; -) sex-dependent peculiarities of realization.     

Age-related characteristics of the stromal-parenchymal relations of the human thymus

In 155 thymuses and in 57 capsules of the organ, distributed according to 12 age groups, beginning from fetuses of 5 months up to 90 years, age transformations of stromal-parenchymatous relations of the human thymus have been studied and quantitatively estimated. During the postnatal ontogenesis the thymic capsule and its intraorganic connective, tissue frame together with the parenchyma undergo certain phase reorganizations, specific for each age period. The greatest development of the thymic connective tissue frame reaches at the age of 1-3 years and during sex maturation period. The thymic lymphoepithelial tissue exists during all age periods. In the thymic adipose body foci of extramedullary lymphopoesis are revealed, beginning from the first mature up to the elderly age.