bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Expectations of Polar Body Twinning
Authors: Goldgar D.E. , Kimberling W.J. 
Published: July 2016

The expected correlation between polar body twins depends upon the frequency and distribution of chiasmata occurring during oogenesis. We have estimated the expected values of these correlations using assumptions believed to be biologically valid. The expected value of the overall correlation between first polar body twins is estimated to be 0.38 and that between second polar body twins is estimated to be 0.51. There is little difference between the correlation of DZ twins and that expected for second polar body twins.The correlation for a specific locus depends upon its distance from the centromere for both types of polar body twins. This effect is especially marked for second polar body twins. For second polar body twins, loci at or near the telomere will have a correlation close to that expected for first polar body twins. It is concluded that only those marker genes that lie at or close to the centromere are appropriate for the detection of polar body twinning.
Quinacrine Mustard and Nucleolar Organizer Region Heteromorphisms in Twins
Authors: Morton C.C. , Corey L.A. , Nance W.E. , Brown J.A. 
Published: July 2016

Patterns of NOR activity in 640 metaphase spreads from twelve monozygotic (MZ) and eight dizygotic (DZ) twin pairs were studied to evaluate the heritability of this chromosomal heteromorphism. NORs were stained by a modification of the Ag-AS technique and counterstained with quinacrine mustard dihydrochloride to facilitate chromosome identification and assess their value in zygosity determination. In this study, all karyotypes were read blind with respect to zygosity and pair membership.A discriminant function analysis of pair score differences in MZ and DZ twins revealed that, in our sample, the probability of accurately determining zygosity with NOR scores was 0.93 and with QFQ scores was 0.99. We conclude that NOR and QFQ scores are highly heritable and of great value in zygosity determination.Data were collected from 687 metaphase spreads on the frequency with which an acrocentric chromosome was found in a satellite association. A significant correlation was found between this frequency and the degree of Ag-AS stain of the NOR. This study, therefore, confirms previous results showing that a high degree of NOR activity is found in those chromosomes most often involved in satellite associations.
The Effects of Hospitalization for Bed Rest on Duration of Gestation, Fetal Growth and Neonatal Morbidity in Triplet Pregnancy
Authors: Crowther C.A. , Verkuyl D.A.A. , Ashworth M.F. , Bannerman C. , Ashurst H.M. 
Published: July 2016

AbstractNineteen women attending a special multiple pregnancy antenatal clinic with a triplet pregnancy were randomly allocated to either bed rest in hospital from 24 weeks gestation onwards until delivery, or to continue conventional outpatient management. Conclusions are limited by the trial size, but the study suggests that routine hospitalization for bed rest decreases the incidence of preterm delivery and light-for-gestational age infants and reduces the need for intensive neonatal care. Although still compatible with change variation, the observations, if confirmed in a larger randomized study, would have considerable implications for clinical practice. The policy needs further evaluation in a large multicentred collaborative study.
Estimates of Genetic and Environmental Components of Serum Isocitrate Dehydrogenase (ICDH) in Normal Twins
Authors: Rapaport D. , Colletto G.M.D.D. , Vainzof M. , Zatz M. 
Published: July 2016

AbstractEnvironmental (b2) and genetic heritability (h2) of serum isocitrate dehydrogenase (ICDH) were estimated in 96 pairs of healthy twins according to a path analysis model. The results showed significant heritability (0.42) and a very low environmental component (based on obesity and level of habitual physical activity), suggesting that these factors do not influence ICDH serum activity.
Presence of an Endothelioid Tubelike Structure at the Interface of the Amniotic Membranes in Twins with Single and Double Placenta. Growth Factors Involvement
Authors: Bondì M. , Brenci G. , Bondì M. 
Published: July 2016

AbstractA histomorphological study of the amniotic membranes in full-term twins with double and single placenta was carried out by means of the silver impregnation staining technique suitably modified. Specimens of interface of amniotic membranes were prepared by means of sections. The constant presence of a tubelike structure was observed. Proceeding from the amniotic cavity, the following histological layers were noted: 1) single layer of amniotic cells; 2) amorphic substance with fibrocytes; 3) single layer of endothelial cells. The same order of single layer is present in the amniotic membrane of the second fetus. This tubelike structure is present only in cases of twins with double placenta. If the placenta is single with two umbilical cords, the tubelike structure is not present and only a central amorphic substance surrounded by two single layers of amniotic cells is observed, to confirm the single embryogenetic derivation (monovular). Therefore, through this histological method, we can recognize the true single placenta of twin pregnancy from the pseudosingle placenta so said for the presence of adherences of adjoining surfaces that make it appear single. On the contrary, by manual dissection it is possible to identify a twin pregnancy with two placentae. From the physiological point of view, the walls of the tubelike structure have probably the function to realize exchanges of amniotic liquids between the two fetuses, so as to obtain a balance of electrolytic ions and of intercavity pressure. Growth factors (vascular endothelial factor) are probably involved in the genesis of the endothelial tubelike structure.
Genetic and Environmental Control of Blood Pressure in Twins and Their Family Members
Authors: Tishler P.V. , Lewitter F.I. , Rosner B. , Speizer F.E. 
Published: July 2016

AbstractAn interdisciplinary study, in adult twins and their family members, of the genetic and environmental determinants of complex physiologic functions is in progress. This report summarizes our initial studies of the control of the level of systolic (K1) and diastolic (K5) blood pressure in 202 monogygotic (MZ) and 121 dizygotic (DZ) twins, their spouses and their children. Correlation coefficients for blood pressure were adjusted for the covariates age, sex, body mass index (wt/ht2) and screener, all of which significantly augment most correlations. These adjusted correlation coefficients in MZ twins are 0.5 for both K1 and K5 blood pressure. For DZ twins, the adjusted correlation coefficients are 0.21 (K1) and 0.24 (K5). MZ twin-offspring adjusted correlation coefficients are higher than MZ twin-niece/nephew adjusted correlation coefficients (0.12 and 0.06, respectively, for K1; 0.20 and 0.13, respectively, for K5), despite the genetic identity of these relationships. That environmental factors may explain these differences is suggested by other differences in adjusted correlation coefficients that are greater than those predicted by the degree of genetic similarity. In addition, we have assessed the relationship between two biochemical-physiological processes, the urinary excretion of kallikrein and transport of sodium in the erythrocyte (the sodium countertransport and the sodium-potassium-chloride cotransport systems), and blood pressure control, since both have been implicated in the control of blood pressure level. Although we found evidence for substantial genetic control of both phenomena, we were unable to establish any correlation between either function and the level of blood pressure in our normotensive subjects.These data point to the operation of three broad categories of control of level of blood pressure: constitutional factors (age, sex, body mass), genetic factors and environmental factors. The identities of the genetic and environmental factors are unknown at this time.
A Family Study of Developmental Effects upon Blood Pressure Variation
Authors: Sims J. , Carroll D. , Hewitt J.K. , Turner J.R. 
Published: July 2016

AbstractIn an earlier study of blood pressure variation in middle aged parents and their young adult twin offspring, the greater blood pressure variation observed in the parent sample was accounted for in terms of an increasing influence of individual environmental experiences with increasing age and a commensurate reduction in the impact of heredity. In the present study, the sample size was enlarged to provide a more powerful test of these effects. Maximum likelihood model-fitting techniques were applied to blood pressure covariation in balanced pedigrees, consisting of 85 families (40 MZ and 45 DZ twin pairs). As before, our analysis indicated that a developmental effect was a salient factor in the older age group.
Genetic Variance Estimates and Familial Resemblance for Body Size Traits
Authors: Sharma Krishan 
Published: July 2016

AbstractTo study genetic contribution to complex body size traits, the intrafamilial correlation and regression analyses along with twin study method have been used. The data are based on a sample of 45 MZ and 101 DZ twin pairs, their 125 singleton siblings, 104 fathers and 103 mothers in 146 Punjabi families living in Chandigarh, India. Twin study gives no evidence of inequality of means and variances between zygosities. Within-pair genetic variance ratios, correlations, regressions of offspring on midparent and single parent are all significant at 0.1%, thus indicating strong genetic component. Heritability estimates are higher for longitudinal body traits than the breadth dimensions. The resemblance of the children with the parents of either sex is not equal. Higher maternal influence is indicated for a number of body traits. The results on familial correlations do not support the hypothesis of sex-linked inheritance for any of the traits considered in this investigation. These results have been compared with those from other such studies.
Twins and Chronogenetics: Correlated Pathways of Development
Authors: Wilson Ronald S. 
Published: July 2016

The study of developmental processes in twins furnishes a powerful resource for examining the role of gene-action systems in guiding the course of growth [2,9].While there is a steady and rapid progression from birth onward, the growth rate is not entirely uniform for a given child, but rather moves in episodes of acceleration and lag. The timing of the growth spurts follows a distinctive pattern for each child, and consequently a child who may be smaller than average at one age may then enter a phase of rapid growth, and ultimately catch up with or surpass his peers at a later age.The effect of such individualized patterns of growth is that many children may change in relative size from one age to the next; and in this sense it may appear that the underlying developmental processes are erratic, rather than coherent. But if there is an underlying ground plan, a chronogenetic pattern, then the distinctive developmental gradients should unfold in synchrony for twins sharing the same genetic make-up. Episodes of acceleration and lag in growth would then occur in parallel for both twins and would presumably represent the activity of timed gene-action systems, which switch on and off according to a predetermined plan.
Features of Interaction in Infant Twins
Authors: Clark P.M. , Dickman Z. 
Published: July 2016

AbstractTwins, more than any other home reared infants, experience intimate and usually continuous interaction with an age-mate from early infancy. The effects of this situation are examined and its implications for both the emotional and cognitive development are discussed in the light of evidence from two studies in which play sessions were video-recorded and subsequently analysed into behavioural categories. The first was a longitudinal study of a single pair of twins, while the second was a short-term study of interaction and cooperation in infants in the 9 to 20 months range. Five pairs of twins, 5 pairs of familiar peers, and the children's mothers were observed playing a structured cooperative game. The hypothesis is advanced that twins enjoy more emotional support but less intellectual stimulation than singletons and it is suggested that social enrichment of the environment of twins could foster social and cognitive development.
Twin Similarity in the Developmental Transformations of Infant Temperament as Measured in a Multi-Method, Longitudinal Study
Authors: Matheny Adam P. 
Published: July 2016

AbstractIn the Louisville Twin Study, laboratory observations of twin infants' temperament at 12, 18, and 24 months were linked with parental ratings from temperament questionnaires. Core dimensions of temperament were extracted by factor analysis applied to each set of measures at each age. The laboratory temperament dimension was recurrently represented by emotional tone, social orientation, attentiveness, and reaction to restraint. The questionnaire temperament dimension was recurrently represented by mood, approach/withdrawal and adaptability. The laboratory and questionnaire dimensions were found to be correlated at each age (convergent correlations: 0.38 to 0.52) and to be stable across ages (stability correlations 0.37 to 0.66). The temperament dimensions were used to demonstrate that temperament profiles were more concordant for identical than for fraternal twin pairs. The results demonstrate the genetic influences on (a) the primary dimensions of temperament and (b) the developmental transformations of temperament.
The High Incidence of Reading Disability in Twin Boys and Its Implications for Genetic Analyses
Authors: Hay D.A. , O'Brien P.J. , Johnston C.J. , Prior M. 
Published: July 2016

AbstractIn 1975 the Australian Council of Educational Research (ACER) conducted a nationwide survey of literacy and numeracy in 10- to 14-year olds. A total of 297 of the 12875 children involved were twins. By age 14, only 42% of the twin boys achieved adequate standards of literacy compared with 71% of single-born boys. The deficit in twin girls was much less and twins of both sexes were only moderately behind in numeracy. A survey of 9-13-year-old twin boys in the La Trobe Twin Study (LTS) produced similar results with 75% being below average in reading skills and 23% behind by 18 months or more, despite above average IQs. The ACER data are corroborated by teachers' reports obtained in the same survey, which indicate also how few of the twins with problems are receiving remediation and the high incidence of classroom problems in spelling and reading reversals. The pattern of mistakes twins make on specific items in the ACER survey can be explained as resulting either from specific cognitive deficits or from problems in concentration. The same factors influence performance on different tasks, so that literacy and numeracy are much more closely interrelated in twins than in singletons, and also correlate more with a measure of verbal intelligence. Implications for genetic analysis of scholastic achievement are examined, centering around the different factor structure of abilities in twins and common family environmental effects which are unique to twins.
Antenatal Genetic Studies in Twin Pregnancies
Authors: Redwine F.O. , Cruikshank D.P. , Brown J. 
Published: July 2016

AbstractThe diagnosis of multiple gestation at the time of genetic amniocentesis is a routine occurrence. In a combined series of 2765 patients referred for antenatal genetic studies from the Medical College of Virginia and the University of Iowa, 34 twin pregnancies were encountered (1.2%). Twenty-six of the patients with twins were referred for advanced maternal age. The other indications were previous neural tube defects (1), previous trisomy 21 (2), known carriers of Tay Sachs disease (2), previous Turner's syndrome (1), family history of trisomy 21 (1), and one pregnancy was referred because of an abnormal ultrasound. Amniocentesis procedures, outcome of the twin pregnancies, and genetic counseling issues, are discussed.
Congenital Heart Defects and Twinning
Authors: Burn J. , Corney G. 
Published: July 2016

AbstractA preliminary analysis of twins or triplets with heart defects, ascertained in five centres, confirms earlier suggestions that monozygotic (MZ) twins are over represented among twins with heart defects, even after excluding persistent ductus arteriosus and conjoined twins. An MZ twin individual has a risk of cardiovascular malformation approximately twice that of DZ twins and singletons. It is suggested that the twinning process itself affects one of the pair. Disturbance of laterality (‘mirror imaging’) is probably a more important mechanism than twin-twin transfusion. Inappropriate use of the twin method in the past has caused the importance of genetic factors in the etiology of congenital heart defects to be underestimated. Neverthless, twins do provide a useful illustration of the likely importance of epigenetic factors in heart development.
Malformations in Twins and Their Siblings, Norway, 1967-79
Authors: Windham G.C. , Bjerkedal T. 
Published: July 2016

AbstractDuring 1967-79 the population-based Medical Birth Registry of Norway registered 7,660 twin pairs (1% of births) born to 7,596 mothers, who gave birth to 6,608 additional infants (twin siblings). The total rate of malformations among twins (278.1/10,000) was not significantly different than among singletons (302.1/10,000), nor among twin siblings (314.8/10,000). By specific type of defect, twins had significantly higher rates than singletons of central nervous system (CNS) defects (Rate Ratio = 1.8) and cardiovascular defects (RR = 1.5). The twins also had a significantly low rate of congenital hip dislocation (RR = 0.4), which may explain the relatively low incidence of malformations in twins. Like-sex (LS) twins had a slightly higher rate of malformations than unlike-sex (US) twins (RR = 1.1), as well as a higher rate of CNS defects (RR = 3.0). The siblings also had a significantly increased rate of CNS defects compared to singletons (RR = 1.9), but not of cardiovascular defects (RR = 0.9). The results indicate that twins have elevated rates of at least some congenital malformations. The observations about CNS defects suggest common factors that can lead to either like-sex twinning, CNS defects, or both. The increased frequency of cardiovascular defects in twins appears to be associated with the biologic conditions of twinning.
Problems of Ascertainment of Congenital Anomalies
Authors: Little J. , Carr-Hill R. A. 
Published: July 2016

AbstractProblems of ascertainment bedevil the investigation of the etiology of congenital anomalies in singletons and in multiple births by epidemiological methods. It is shown that the definition of the population of affected births is ambiguous and that the problem of tracing etiology is complicated by the systematic way in which anomalies may be missed at birth. The available methods of dealing with problems of ascertainment are reviewed. Methods of adjusting for possible bias of ascertainment of affected births, by fitting statistical models to data from several sources, have been employed in some previous studies. In these methods, it is assumed that there are no errors of diagnosis or of recording. However, it is shown that there may be discrepancies in recorded diagnoses between sources, rendering this assumption untenable. In these methods, it is also assumed that the model which is the best fit to the data on the ascertained cases in also the best model for the cases which were not ascertained. This assumption is tested indirectly in a retrospective analysis of data from Aberdeen and Belfast collected concurrently through routine recording systems. It is demonstrated that there was a social process in ascertainment which renders the methods of adjusting for bias of ascertainment at best very complicated and at worst inapplicable.
Twinning Rate by Month of Mother's Birth in Japan
Authors: Miura T. , Nakamura I. , Shimura M. , Nonaka K. , Amau Y. 
Published: July 2016

AbstractRecords of two hospitals and of an association of mothers of twins were analysed for the years 1924-1980, finding a total of 656,109 and 1185 twin births, respectively. Twinning rates were higher in summer or fall, in general, but these seasonal variations occasionally changed within a short period of years, as in 1973-75 in the Association group. The twinning rate was also affected by the month of mother's birth. It was low among the mothers born around May-July in maternities up to 1960, and these mothers did not show seasonal variation of twin births. The unlike-sexed twinning rate of the mothers born in May-July was also lower than that of the other mothers, and constantly low even at higher maternal ages. A possible explanation for these phenomena is discussed.
Chromosome Studies on the Effect of Primidon (MylepsinumR) and Its Metabolites, Phenobarbital and Phenylethylmalondiamide, in Vitro
Authors: Foerst Dieter 
Published: July 2016

SummaryPrimidone and its metabolites Phenobarbital and Phenylethylmalondiamide were tested in cultures of human lymphocytes on possible effects of inducing chromosome aberrations. The substances examined ranged from concentrations lower than the therapeutic serum level to 10-75 times this value, which differed with the various substances. Phenylethylmalondiamide shows, besides an increase of spiralization defects at higher concentrations, which was typical for all three substances, no reaction on the chromosome structure.By using the Friedman-test a statistically significant difference (P< 5%) could be found between the average aberration rates of the controls and the cultures which had been treated with Primidone and Phenobarbital. The test according to Wilcoxon and Wilcox shows that there is a statistically significant (P< 5%) difference between the aberration rates of controls and the respectively treated cultures. The higher values for percentage of aberrant mitoses are caused by the increase of gaps and breaks. There was, however, no proof for a linear dependence of the percentage of aberrant mitoses on the increasing concentrations of the substances. The number of tetraploid mitoses, endoreduplications and hyperploid cells was within the normal range.Since in these investigations the number of chromosome exchanges was not increased, it can certainly be said that Primidone and Phenobarbital are not highly mutagenic substances.