bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Monozygotic Twinning Rate: Is It Really Constant?
Authors: Allen G. , Hrubec Z. 
Published: July 2016

AbstractWeinberg's difference method, applied to twin birth statistics, usually shows a dependence of the MZ rate on maternal age, like a thin shadow of the DZ rate. Some of this MZ variation could be explained away by James' finding of more same-sex (SS) than opposite-sex (OS) DZ twins, the excess being mistakenly classified as MZ by Weinberg's assumption of equal numbers. By several methods one can extract a Constant value for the MZ rate and a Constant or nearly Constant value for the DZ SS/OS ratio, but these “constants” are actually arbitrary and they vary between populations.
Increasing Trend in the Monozygotic Twinning Rate
Authors: Bressers W.M.A. , Eriksson A.W. , Kostense P.J. , Parisi P. 
Published: July 2016

AbstractRecent changes in the estimated incidence of monozygotic twinning in 15 European populations are described. The overall trend was an increase in the monozygotic twinning rate (MZTR) since the 1960s, particularly in those countries in which the use of oral contraceptives (OC) was widespread. A slower increase or even a decrease in the MZTR was observed in countries with low use of OC. Some countries, eg, Sweden, demonstrated an unexpectedly sharp increase since the 1960s. In Poland and the Federal Republic of Germany the MZTR was already strongly increasing as early as in the 1950s, clearly before the introduction of the pill. The influence of several other factors on the MZTR is discussed, such as toxic and teratogenic agents, pelvic infection diseases caused by the use of intrauterine devices, the increased use of ovulation inducers and neuroleptics as well as changes in the registration of perinatal deaths.
Does the Use of Oral Contraception Depress DZ Twinning Rates?
Authors: Campbell D. , Thompson B. , Pritchard C. , Samphier M. 
Published: July 2016

AbstractData based on total births from a geographically defined population with zygosity determined from blood samples and placentation and with data on the use of oral contraceptives routinely collected in early pregnancy showed no association between oral contraceptive use prior to pregnancy in either MZ or DZ twinning. Three mutually exclusive control groups of singletons were used to take account of age, parity and secular trends.
The Organization of the Oocyte and Embryogenesis in Twinning and Fusion Malformations
Authors: Boklage Charles E. 
Published: July 2016

AbstractCertain congenital malformations occur in excess among twins and also among first-degree relatives of twins. In the general population, these anomalies are familially associated with each other, and, like twinning, familially associated with unusual brain function asymmetry. They affect structures built by fusion of bilateral embryonic halves and remodeled under major influence of neural crest mesenchyme. This conjunction of associations suggests that twinning, symmetry development, and this group of malformations might share causai elements at least some of which are heritable. The problem here is the absence of zygosity differences in these relationships, because of which they cannot be explained within the biology of twinning as it has been understood. A potential resolution is offered by way of a mechanism common to MZ and DZ twinning, involving a relationship between oocyte organization and the determination of body symmetries.
Familial and Individual Influences on Blood Pressure
Authors: Sims J. , Hewitt J.K. , Kelly K.A. , Carroll D. , Turner J.R. 
Published: July 2016

AbstractAlthough familial aggregation of blood pressure is well documented, few studies have considered the changing contribution of genetic and environmental influences during adulthood. Applying maximum likelihood model fitting to blood pressure covariation in balanced pedigrees including both parents and their young adult twin offsprings (25 MZ, 32 DZ, aged between 16 and 24 years), it is shown that the increased variation in parents is explained by such developmental changes. For DBP, an apparent reduction in heritability from 68% to 38% from young adulthood to middle age results from the increasing impact of individual environmental experience (E1), with little or no influence from shared family environmental (E2). For SBP, shared environmental effects may play a part. Given the relatively small size of the present sample, the conclusions are to be seen as tentative. An augmented family study, incorporating middle aged twins and their young adult offspring, will clarify the causation of these developmental changes.
Heritability Estimation from Concordant Twin Pairs Alone
Authors: Sofaer Jeffrey A. , Holloway Susan M. 
Published: July 2016

AbstractHeritability estimation is possible from concordant twin pairs alone, based on the proportion of like-sexed pairs among all concordant affected pairs. The method is limited to conditions found in both sexes in the prevalence range 0.1% to 10%, and a relatively large population size is required to give an adequate sample of twin pairs. However, the method has the considerable advantage that zygosity determination is not required and that any bias due to incomplete diagnosis/ascertainment is likely to be small. The method is particularly suited to diseases where registration is obligatory and computerised so that the register can be scanned for pairs of individuals with the same date of birth, place of birth and birth surname.
Outcome of the Surviving Cotwin of a Fetus Papyraceus or of a Dead Fetus
Authors: Yoshida K. , Soma H. 
Published: July 2016

AbstractSerial ultrasound examinations have demonstrated that one of two gestational sacs in a twin pregnancy may often disappear. When it disappears at an early stage of gestation, the pregnancy may advance without any disturbance and the cotwin can be delivered well developed and lively. When the intrauterine death occurs in the second trimester, the dead fetus usually results in a fetus papyraceus and the cotwin continues to be alive near term. However, when death occurs in the last trimester, the viable twin may be spontaneously delivered soon and be premature. In some cases of late fetal death, the dead fetus may induce intravascular thromboses in many organs of the surviving cotwin, so that the living infant may develop cerebral palsy later after birth.
Smoking and Drinking Discordance and Health Condition: Japanese Identical Twins Reared Apart and Together
Authors: Hayakawa Kazuo 
Published: July 2016

AbstractA total of 543 like-sex pairs of twins (407 MZ, 136 DZ) were sent mailed questionnaires on cigarette smoking, alcohol drinking and health conditions. The observed concordance rate for alcohol drinking was significantly higher than expected in both MZ and DZ pairs. The observed concordance rate for cigarette smoking was significantly higher than expected in the MZ, but not the DZ pairs. The observed rate of intrapair concordance for drinking was significantly higher than expected even in MZ pairs reared apart from infancy or very early childhood. Higher life satisfaction was observed more often in the higher alcohol consumers than in the lower consumers among MZ pairs discordant for alcohol drinking, while earlier onset of presbyopia was observed more often in the lower consumers. Physical symptoms, especially pains in the upper extremities, were reported more often by higher alcohol consumers than by lower consumers in the MZ pairs discordant for drinking.
Intrapair Similarity of Immunoglobulin Levels in Twins
Authors: Kouvalainen K. , Moilanen I. 
Published: July 2016

AbstractLevels of immunoglobulins IgG, IgA, IgM and IgE were determined in 8 MZ and 14 DZ twin pairs at the ages of 6-11 years, 12-17 years and 15-20 years. Intrapair similarity in immunoglobulin levels was found to be higher in the MZ than in the DZ twins, especially in the case of immunoglobulins IgA and IgM.
Twin Studies on Urinary Pepsinogen A Phenotypes and Serum Pepsinogen A Levels
Authors: Pronk J.C. , Boomsma D.I. , Pals G. , Frants R.R. , Overbeke M. , Meuwissen S.G.M. , Orlebeke J.F. , Eriksson A.W. 
Published: July 2016

AbstractUrinary pepsinogen A (PGA or PG I) phenotypes and serum PGA levels were studied in MZ and DZ twins and their parents. In 45 out of 48 MZ twin pairs PGA patterns were completely identical, while 3 MZ twin pairs showed minor differences in the relative intensity of the Pg5 isozymogen. This suggests that the intensity of this isozymogen may be influenced by nongenetic factors. There was little difference in the interclass correlations of serum PGA levels between MZ and DZ twins, indicating a large contribution of common environmental factors to serum PGA levels. This is in contrast with previous studies.
Genetic and Environmental Variation in Menstrual Cycle: Histories of Two British Twin Samples
Authors: van den Akker O.B.A. , Stein G.S. , Neale M.C. , Murray R.M. 
Published: July 2016

AbstractInformation about menstrual cycle variables was obtained by questionnaire using 462 female twin pairs. The twins were either members of the Institute of Psychiatry Volunteer Twin Register, or of the Birmingham Population-based Register. The two samples were analysed separately using univariate and multivariate methods so that an independent replication was obtained. Maximum likelihood estimation was used to fit simple models of genetic and environmental variation to these data. The results suggest that age of menarche, menstrual cycle regularity and premenstrual symptom reporting may be heritable, whereas menstrual cycle length is not. The results should be interpreted with caution as not all variables were replicated in the smaller sample, and the method of retrospective menstrual cycle data collection has been questioned.
Genetic and Environmental Variation of Ridge-Counts on Fingers, Palms, Soles and Toes: A Twin Study
Authors: Jantz R.L. , Brehme H. , Bender K. 
Published: July 2016

AbstractA multivariate procedure for estimating heritable components from twin data was applied to ridge counts obtained from the entire dermatoglyphic system. Covariance matrices of MZ and DZ within-pair differences were used to estimate genetic correlation matrices for 20 finger ridge counts, 6 palmar interdigital counts, 20 toe counts, 4 hallucal counts, and 6 sole interdigital counts. The proportion of genetic variation was found to be greater in ridge counts of patterns than in ridge counts of interdigital areas. On digits, finger counts are more highly heritable than toe counts. Each of the dermatoglyphic areas yielded several independent genetic components, ranging from general to specific. Environmental variation was found to be local and to frequently involve reciprocal interaction between twin pairs.
Adaptation to Maximal Effort: Genetics vs. Environment. A Case History
Authors: DeMeersman R.E. , Schaefer D.C. , Miller W.W. , Nance W.E. 
Published: July 2016

AbstractAn individual's functional ability in physiological responsiveness is thought to be an interaction between his heredity and his environment. This hypothesis was tested to determine if different extragenetic influences would alter functional adaptability in a set of MZ triplets. After a 3-month aerobic physical fitness training program varying only in frequency, measured values for the triplets' maximum oxygen consumption (MaxVo2 ) were 59.1, 44.5, and 57.8 ml/min/kg, as compared to pretreatment values of 45.2,45.1, and 49.1 ml/min/kg respectively. These results clearly indicate intrapair differences in functional adaptability, stemming from difference in the training frequency program. The split-triplet design of this study indicates that environmental factors contribute substantially to the intrapair variance found among MZ siblings. Data extrapolation suggests that environmental stimulation of sufficient magnitude is likely to alter the functional adaptability in the individual set by his genotype.
Finnish Twins Reared Apart II: Validation of Zygosity, Environmental Dissimilarity and Weight and Height
Authors: Langinvainio H. , Koskenvuo M. , Kaprio J. , Sistonen P. 
Published: July 2016

AbstractWithin the Finnish Twin Cohort of like-sexed adult twin pairs, a subgroup of pairs separated at an early age has been identified. In 165 pairs, both cotwins responded to questionnaires in 1975 and 1979. An environmental dissimilarity score was formed which consists of items on whether the twins had lived after separation in the same community, attended the same school, were on the same grade at school, how often the cotwins met, how often they met common friends and relatives and whether they attended the same clubs etc, or not. To validate the zygosity diagnosis obtained by questionnaire in 1975, those pairs whose zygosity was unknown as well as those with the least contact after separation were contacted for blood sampling (11 bloodgroups). Of 15 pairs with no zygosity diagnosis, 10 responded (1 no address,2 abroad,2 refused). Six pairs were classified MZ and 4 DZ. In 12 MZ and 8 DZ pairs undergoing bloodgroup determination, the classification of only one pair changed from DZ to MZ. The following intraclass correlations for height and weight were found:
Altruism and Genetics
Authors: Rushton J.P. , Fulker D.W. , Neale M.C. , Blizard R.A. , Eysenck H.J. 
Published: July 2016

AbstractThree questionnaires measuring altruistic tendencies were completed by 573 adult twin pairs from the University of London Institute of Psychiatry Volunteer Twin Register. The questionnaires consisted of a 20-item Self-Report Altruism Scale, a 33-item Empathy Scale, and a 16-item Nurturance Scale, all of which had previously been shown to have construct validity. For the three scales, the intra-class correlations for the 296 MZ pairs were 0.53, 0.54, and 0.49, and for the 179 same-sex DZ pairs were 0.25,020, and 0.14, giving rough estimates of broad heritability of 56%, 68%, and 72%, respectively. Maximum-likelihood model-fitting revealed about 50% of the variance on each scale to be associated with genetic effects, virtually 0% to be due to the twins' common environment, and the remaining 50% to be due to each twins' specific environment and/or error associated with the test.
Depression, Criminality and Psychopathology Associated with Alcoholism: Evidence from a Twin Study
Authors: Gurling H.M.D. , Oppenheim B.E. , Murray R.M. 
Published: July 2016

AbstractA study of 74 twin pairs with alcoholic probands from the Maudsley Hospital is reported. Pairwise concordance for alcoholism as categorised by the SADS-L Research Diagnostic Criteria is similar in MZ twins (29%, 8/22) and DZ twins (33%, 13/39). Concordance for all diagnoses other than alcoholism is however significantly greater in MZ twins (48%, 13/27) than DZ twins (21%, 8/39, P < 0.001). Concordance in MZ and DZ twins for all diagnoses other than alcoholism, inlcuding depression, did not coincide with concordance for alcoholism. Data on criminality revealed that 21% (32/148) of the twin sample had non-alcohol, non-traffic offences on record at the UK Home Office. Of the 32 with criminal records, 28 were alcoholic probands and pairwise concordance for criminality was found in only 1 MZ and 2 DZ pairs.
Spontaneous Abortions and Twinning
Authors: Zahálková M. , Zudová Z. 
Published: July 2016

AbstractThe relation between spontaneous abortions and twinning was studied in the years 1980-1981 in 22 towns of the South Moravian Region, Czechoslovakia. Each town has more than 10,000 inhabitants and less than 750 births per year. The number of spontaneous abortions and the number of twin births were evaluated separately for each town and for a time unit of three months. The comparison indicated that the group with a higher number of spontaneous abortions also had a lower number of twin births. The relation between spontaneous abortions and twinning is discussed.
A Study of Twin Placentation in Tokyo
Authors: Yoshida K. , Soma H. 
Published: July 2016

AbstractA total of 178 placentas of twins born in Tokyo in 1961-1982 were examined. Only just over one third were dichorionic, 110 being monochorionic and DZ twins were estimated to account for 24.7% of the pairs. The lower frequency of DZ twinning in Japan is attributed to lower gonadotropin values in Japanese women as compared to European, American, or African women. High fetal morbidity was found in monochorionic twins and this is attributed to a frequent occurrence of vascular anastomoses.
Term Twins With Discordant Birth Weights: Observations at Birth and One Year
Authors: Philip Alistair G. S. 
Published: July 2016

Sixteen pairs of term discordant twins (weight discrepancy of more than 20% when the, lighter twin was compared to the heavier) were evaluated at birth. Weight, length, head circumference, anterior fontanel area, and combined ossification of the knee epiphyses were measured, and ponderal index (weight/length ratio) calculated. The most severely growth retarded infants had markedly decreased ossification and larger anterior fontanels.Eleven pairs had physical measurements at one year of age. With individual exceptions, the lighter twins at birth remained smaller in all dimensions. Despite these persistent differences between twin pairs, the values for length at one year of age were within normal limits for both the heavierandlighter twins. Infants without ossification at birth had a greater incremental linear growth by one year than those infants with ossification.
Perinatal Profile of Twin Pregnancies:A Retrospective Review of 11 Years (1969–1979) at Hôpital Notre-Dame, Montréal, Canada
Authors: Desgranges Marie-Françoise , De Muylder Xavier , Moutquin Jean-Marie , Lazaro-Lopez Francisco , Leduc Bernard 
Published: July 2016

Four hundred and thirty four twins occurring in 220 women were studied during a period of 11 years (1969–1979) at Notre-Dame Hospital.Perinatal mortality (< 28 days) was compared before and after 1974, and the impact of ultrasound technique upon perinatal outcome was assessed during the second period (1974–1979). The main factor associated with perinatal mortality was low birth weight caused by either prematurity or intrauterine growth retardation.While fetal mortality remained unchanged within the two study periods, neonatal mortality decreased from 68.2/1,000 to 28.9/1,000 mainly due to increased survival rate of twins below 1,500 g at birth.With identical perinatal care during the same period, perinatal mortality and incidence of intrauterine growth-retarded twins remained unchanged despite early diagnosis by ultrasound.
The Association of Twinning and Neural Tube Defects: Studies in Los Angeles, California, and Norway
Authors: Windham Gayle C. , Bjerkedal Tor , Sever Lowell E. 
Published: July 2016

Accurate, unbiased malformation rates in twins must be obtained unselectively from population-based studies that include livebirths and stillbirths after a thorough ascertainment of cases. This type of study was conducted in Los Angeles County, California, where 28 twins with a neural tube defect (NTD) were identified. The prevalence in twins (1.6/1,000) was significantly higher than in singletons (1.1/1,000). The study then was expanded to include population-based data from the Medical Birth Registry of Norway which has a comparable overall NTD prevalence (1.0/1,000) and twinning rate (2%). The combined material shows a higher prevalence of anencephaly and encephalocele but not of spina bifida in twins compared to singletons. The male/female ratios in total twin and singleton cases were comparable (0.8), but varied by specific defect. Like-sex twin females appeared at highest risk for NTD as well as for fetal death.This study supports theories which associate NTDs with monozygotic twins, either through developmental disruptions that cause susceptibility to environmental agents or through a common etiology. Furthermore, it suggests that twins and singletons differ in their response to etiologic factors for the development of NTDs and that the development of each type of NTD may be related to different factors.
The Human Twin
Authors: Gedda Luigi 
Published: July 2016

For the geneticist, or for anyone else, to make a speech in Jerusalem means a cultural effort that is extraordinary. Like every other researcher, the geneticist must locate his scientific investigations in the context of a truth which embraces nature and the history of man. Those of us who are concerned with twin studies, however, cannot simply leave our concrete and specific field to deal with theoretical themes; rather, we must extract from our research these concepts that bridge the gap between the particular truths we seek and that total truth, which man desires in order to resolve the mystery which surrounds his existence.I would like to submit to the distinguished personalities who are honoring our Congress with their presence, as well as to my very dear colleagues, the idea that the best project for creating a link between our field of interest and the other interests of modern culture would be to survey the state of our knowledge about the personality of the human twin.Therefore, I will not talk about the application of the method of twin studies, but about the identical twin, the monozygotic (MZ) twin individual. That is, I will not talk about those dizygotic (DZ) twins like Esau and Jacob, who were different. DZ twins are, of course, real twins, and about twice as frequent as the MZ ones. But I will refer only to the twin who has another twin identical to himself, and who represents the classical model of the phenomenon of twins.
A Case of Simultaneous Interstitial Bilateral Pregnancy
Authors: Pezzani M. 
Published: July 2016

Twin pregnancies may present tubal involvement in the following cases: (1) simultaneous intra- and extrauterine pregnancy; (2) interstitial bilateral pregnancy (either simultaneous or not); (3) multiple pregnancy in the same tube; and (4) simultaneous interstitial and ovarian pregnancy.Interstitial bilateral pregnancy appears to be by far the rarest kind of tubal twin pregnancy, apparently only one case having been reported in the literature, and this referring to a nonsimultaneous pregnancy. A case is now reported that therefore appears to represent the first observation of simultaneous interstitial bilateral pregnancy.
Studies on the flow of zinc, cobalt, copper and manganese along the digestive tract of sheep given fresh perennial ryegrass, or white or red clover
Authors: Grace N. D. 
Published: July 2016

1. Sheep fitted with a rumen fistula and either a re-entrant cannula at the proximal duodenum or a re-entrant cannula at the terminal ileum were given twice daily 480–520 g dry matter as fresh perennial ryegrass, or white or red clover. Flows of digesta were corrected to 100% recovery of chromic oxide.2. The quantities (g/24 h) of zinc and cobalt leaving the stomach were significantly greater than those in the food. No significant change was found in the quantities of copper and manganese. Significantly smaller quantities of Co (all three diets) and Zn (all diets except red clover) left the small intestine than those which entered this region. No significant differences in the quantities of Cu and Mn entering and leaving the small intestine were found. Significantly smaller quantities of Zn, Co, Cu and Mn were excreted in the faeces than entered the large intestine.3. From the flow results it was determined that there was a significant net secretion of Zn and Co in the stomach, and a significant net absorption of Zn (except with the red-clover diet) and Co from the small intestine, and of Zn, Co, Cu and Mn from the large intestine.