Associations between birth size and later height from infancy through adulthood: An individual based pooled analysis of 28 twin cohorts participating in the CODATwins project

BACKGROUND

There is evidence that birth size is positively associated with height in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment.

AIM

To analyze the associations of birth weight, length and ponderal index with height from infancy through adulthood within mono- and dizygotic twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

METHODS

This study is based on the data from 28 twin cohorts in 17 countries. The pooled data included 41,852 complete twin pairs (55% monozygotic and 45% same-sex dizygotic) with information on birth weight and a total of 112,409 paired height measurements at ages ranging from 1 to 69 years. Birth length was available for 19,881 complete twin pairs, with a total of 72,692 paired height measurements. The association between birth size and later height was analyzed at both the individual and within-pair level by linear regression analyses.

RESULTS

Within twin pairs, regression coefficients showed that a 1-kg increase in birth weight and a 1-cm increase in birth length were associated with 1.14-4.25 cm and 0.18-0.90 cm taller height, respectively. The magnitude of the associations was generally greater within dizygotic than within monozygotic twin pairs, and this difference between zygosities was more pronounced for birth length.

CONCLUSION

Both genetic and individual-specific environmental factors play a role in the association between birth size and later height from infancy to adulthood, with a larger role for genetics in the association with birth length than with birth weight.

Differential expression of four sweet potato peroxidase genes in response to abscisic acid and ethephon

Expression of four peroxidase (POD) genes, three anionic PODs (swpa1, swpa2 and swpa3), and one neutral POD (swpn1) isolated from suspension cultures of sweet potato (Ipomoea batatas) were analyzed by measuring the accumulation of transcripts in suspension cultured cells and leaves of sweet potato in response to the stress-related plant hormones abscisic acid (ABA) and ethephon (an ethylene generating chemical). The four genes responded differently to ABA (0.1 mM) and ethephon (0.1 mM) in cultured cells and leaves. In suspension cultures, ABA reduced the expression levels of swpa1, swpa2, and swpn1, but did not affect the level of swpa3. Ethephon strongly increased expression levels of swpa3 and swpn1, and slightly increased the level of swpa1. The expression level of swpa2 was reduced. Expression levels in intact leaves, however, were significantly changed by this treatment. Expression of the swpa1 and swpa2 genes was induced 15 min after ABA treatment, followed by a decrease to a basal level after 3 h. A strong re-expression occurred after 12 h. Expression of the swpa3 and swpn1 genes occurred from 3 to 24 h after treatment. All four genes were differentially expressed 12 h after ethephon treatment. The swpa2 gene was strongly expressed immediately after ethephon treatment. The results indicate that each POD gene is differentially regulated by ABA and ethylene in whole plants and in cultured cells in vitro.

Molecular characterization of cDNAs for two anionic peroxidases from suspension cultures of sweet potato

Two cDNAs for anionic peroxidase (PODs), swpa2 and swpa3, were isolated from suspension cultures of sweet potato (Ipomoea batatas), and their expression was investigated with a view to understanding the physiological function of PODs in relation to environmental stresses. Swpa2 (whose putative mature protein product would have a pI value of 4.1) and swpa3 (4.3) encode polypeptides of 358 and 349 amino acids, respectively. The genes from which they were derived are predominantly expressed in cultured cells of sweet potato; transcripts of swpa2 were not detected in any tissues of the intact plant, and transcripts of swpa3 were detected at a low level only in the stem tissue. During cell culture, the expression patterns of the two genes differed; the level of swpa2 RNA progressively increased during cell growth, whereas that of swpa3 reached a maximum at the stationary phase and decreased on further culture. The two genes responded differently to stresses such as wounding or chilling of leaves. Swpa2 was strongly induced 48 h after wounding, but swpa3 was not affected by this treatment. The two genes were also highly expressed upon chilling (4 degrees C), but expression was reduced by prior acclimation at 15 degrees C. In addition, both genes were strongly induced immediately after treatment with ozone, and expression had decreased to the basal level 12 h after treatment. The response of these two genes to stresses such as aging, wounding, and chilling are different from those of the POD genes (swpa1 encoding an anionic product and swpn1 a neutral peroxidase) that we described previously. The responses of the two genes were also different from each other. These results suggest that the two new POD genes are involved in overcoming oxidative environmental stress, and each POD gene may be regulated by cell growth and environmental stress in different ways.

The structure of self-concept in female preadolescent twins: a behavioral genetic approach

Two hundred and forty-three female monozygotic (MZ) and 164 female dizygotic (DZ) twin pairs, aged 11 and 12 years, who participated in the ongoing Minnesota Twin Family Study, completed six specific scales of the Piers-Harris Children's Self-Concept Scale (P-H). Model-fitting analyses yielded three major conclusions. First, approximately 30% of the variance in specific self-concepts in female preadolescents was due to genetic factors, with the remaining variance being accounted for primarily by nonshared environmental factors and measurement error. Second, the underlying common genetic, shared environmental, and nonshared environmental factors influenced specific facets of self-concept directly and independently, rather than through an intervening phenotypic general self-concept. Finally, whereas genetic, shared environmental, and nonshared environmental factors were necessary to explain the commonality among the specific self-concept scales, only genetic and nonshared environmental factors were sufficient to explain the specificity of those scales.

Genetic and environmental influences on self-reported diet: a reared-apart twin study

A sample of 66 monozyogtic twins reared apart (MZA) and 51 dizygotic twins reared apart (DZA), and 101 nontwin individuals (mostly spouses of the twins) who participated in the Minnesota Study of Twins Reared Apart (MISTRA) from 1979 to 1995 completed a self-report food frequency questionnaire. Intraclass-correlations and model-fitting analyses indicated that approximately 30% of the variance in the self-report of diet was attributable to genetic factors, with random environmental factors and measurement error responsible for the remaining variance. Spouse correlations were moderate. To investigate the effects of living together during marriage, the absolute differences between husband and wife on the dietary variables with years of marriage were correlated. None of the correlations were significant. Hierarchical multiple regression analyses also indicated that no convergence occurred during marriage. These results suggest that sharing a current family environment exerts minimal influence on individual differences in self-reported diet.

Migraine in twins raised together and apart

History of headache and migraine diagnosed by structured interview utilizing International Headache Society criteria was obtained in two samples of female twin pairs--154 raised together and 43 raised apart since infancy. Zygosity was determined by standard methods. Probandwise concordance rates were determined. Assuming that liability to migraine has a multifactorial etiology involving a number of genetic and environmental risk factors acting additively, tetrachoric correlations in the four groups of twins (monozygotic raised together, monozygotic raised apart, dizygotic raised together, and dizygotic raised apart) were then calculated. The genetic and environmental influences in the liability to migraine were estimated using biometrical model-fitting methods. Tetrachoric correlations of migraine were consistently higher in monozygotic than in dizygotic twins, for both reared together and reared apart samples, with a heritability estimate of 52%, Model fitting also suggested that approximately 50% of the variance in liability to migraine was attributable to genetic factors with nonshared environmental factors and measurement errors responsible for the remaining variance.

Spinach cytosolic fructose-1,6-bisphosphatase: II. Light effect on its expression

The effect of light on the expression of spinach (Spinacia oleracea) cytosolic fructose-1,6-bisphosphatase (FBPase) was determined by the level of mRNA, protein content, and enzyme activity. It was found that its expression and activity were constant and stable during normal daily conditions as well as under continuous light or dark conditions. However, two different mRNAs were detected; one transcript was expressed all the time, while the other was detected only during prolonged dark periods. Analysis of the expression of the mRNAs at the protein level using an activity gel showed that this "darkness-specific" mRNA encoded a separate, distinct polypeptide. Thus, our data suggest that cytosolic FBPase is encoded by a small multigene family.

Spinach cytosolic fructose-1,6-bisphosphatase: I. Its organ-specific and developmental expression characteristics

Spinach (Spinacia oleracea) cytosolic fructose-1,6-bisphosphatase (FBPase) was purified and the final preparation of protein has a specific activity of about 45 units/mg protein and a single band of molecular mass of 39 kDa. Polyclonal antibody against the protein did not cross-react with chloroplast FBPase, but showed strong cross-reactivity with all plant cytosolic FBPases tested. Studies of the FBPase expression characteristics at early stages of development demonstrated that it was controlled at both the transcriptional and translational levels, and its mRNA was detected even in etiolated cotyledons. This suggests that the expression is not light-inducible. A single transcript was detected in all spinach tissues tested. Western blot analysis revealed two protein bands in the etiolated cotyledons: one was the same size as that present in the mature leaf, and the other slightly smaller. A high enzyme activity was detected in etiolated cotyledons, especially compared to protein levels in Western blots. Expression of the cytosolic FBPase gene during leaf development showed no change in the steady-state level of mRNA, but the protein level and enzyme activity were higher in mature leaves than in young ones, suggesting that the increase in FBPase activity during development is due to an increase in protein synthesis. Young roots showed low enzyme activity, but an unexpectedly high activity was detected in old fiber roots.

Genetic and environmental influences on the continuous scales of the Myers-Briggs Type Indicator: an analysis based on twins reared apart

The Myers-Briggs Type Indicator was administered to a sample of 61 monozygotic twins reared apart (MZA), 49 dizygotic twins reared apart (DZA), and 92 spouses, who participated in the Minnesota Study of Twins Reared Apart (MISTRA) from 1979 to 1995. Twins' scores on the continuous scales were subjected to behavior genetic model-fitting procedures. Extraversion-Introversion and Thinking-Feeling yielded heritabilities of about .60, consisting largely of nonadditive genetic variance. Sensing-Intuition and Judgment-Perception yielded heritabilities of about .40, consisting largely of additive genetic variance. Spouse correlations for three of the four scales were near zero and not statistically significant; one spouse correlation (Sensing-Intuition) was modestly positive and statistically significant.

The structure of self-concept in female preadolescent twins: a behavioral genetic approach

Two hundred and forty-three female monozygotic (MZ) and 164 female dizygotic (DZ) twin pairs, aged 11 and 12 years, who participated in the ongoing Minnesota Twin Family Study, completed six specific scales of the Piers-Harris Children's Self-Concept Scale (P-H). Model-fitting analyses yielded three major conclusions. First, approximately 30% of the variance in specific self-concepts in female preadolescents was due to genetic factors, with the remaining variance being accounted for primarily by nonshared environmental factors and measurement error. Second, the underlying common genetic, shared environmental, and nonshared environmental factors influenced specific facets of self-concept directly and independently, rather than through an intervening phenotypic general self-concept. Finally, whereas genetic, shared environmental, and nonshared environmental factors were necessary to explain the commonality among the specific self-concept scales, only genetic and nonshared environmental factors were sufficient to explain the specificity of those scales.

The changes in quantitative HCV RNA titers during interferon alpha 2B therapy in patients with chronic hepatitis C infection

OBJECTIVE

Our aim was to analyze the outcomes and the patterns of response to interferon treatment in patients with chronic hepatitis C using serum HCV RNA as the primary endpoint of therapy.

METHODS

Seventy anti-HCV-positive patients were treated with 3 million U of interferon-alpha-2b thrice weekly for 24 wk and followed for an additional 24 wk after cessation of therapy (wk 48). Serum HCV RNA was measured by a reverse transcriptase-polymerase chain reaction method that has a sensitivity of < 100 viral copies per ml.

RESULTS

The mean pretreatment HCV RNA was 2.8 +/- 2.2 x 10(6) viral copies per ml. Genotype 1 patients had significantly higher mean baseline viral titers than those with genotype 2 (p = 0.03). At wk 48, 12 (17%) patients were HCV RNA negative and considered virological complete responders (CR) to treatment. The remaining patients were HCV RNA positive at wk 48 and were considered nonresponders to therapy. There were two types of virological nonresponder patients, responder relapse (RR) and no response (NR). The mean baseline HCV RNA level was significantly lower in the virological CR patients (p = 0.0004). At wk 12 and 24 of interferon treatment, both the virological CR and RR patients had lower serum HCV RNA concentrations than the patients in the NR category (p = 0.0001), while at wk 48, only. the virological CR patients had undetectable HCV RNA when compared to the RR and NR patients (p = 0.04). Transient decreases in the HCV RNA titers of > or = 1 log in magnitude were observed in 49% of the NR patients, which rose to pretreatment levels either during or after interferon therapy.

CONCLUSIONS

Our findings indicate that measurement of serum HCV RNA precisely defined the responses to interferon therapy. Because the goal is to eliminate virus in patients with chronic hepatitis C infection, then HCV RNA should be used as the primary endpoint of treatment.

Plant resistance to fungal infection induced by nontoxic pokeweed antiviral protein mutants

Pokeweed antiviral protein (PAP), a 29-kD protein isolated from Phytolacca americana inhibits translation by catalytically removing a specific adenine residue from the large rRNA of the 60S subunit of eukaryotic ribosomes. Transgenic plants expressing PAP are resistant to a broad spectrum of plant viruses. Nontoxic PAP mutants have been isolated by random mutagenesis and selection in yeast. One of these mutants, PAP-X, had a point mutation at the active-site (E176V) that abolished enzymatic activity, and another mutant, delta C25PAP, had a nonsense mutation near the C-terminus (W237stop) that deleted 25 C-terminal amino acids. Unlike the wild-type PAP, expression of neither mutant was toxic to transgenic plants. We show that both class I (basic) and class II (acidic) isoforms of pathogenesis-related (PR) proteins are overexpressed in transgenic plants expressing PAP and the nontoxic PAP mutants. Although PR-proteins are constitutively expressed, no increase in salicylic acid levels was detected. Homozygous progeny of transgenic plants expressing either PAP or the nontoxic PAP mutants displayed resistance to the fungal pathogen Rhizoctonia solani. These results show that expression of PAP or the nontoxic PAP mutants activates multiple plant defense pathways independently of salicylic acid and confers resistance to fungal infection. The C-terminal 25 amino acids of PAP, which are required for toxicity in vivo, are not critical for resistance to viral or fungal infection, indicating that toxicity of PAP can be separated from pathogen resistance.

The genetic correlation between impulsivity and sensation seeking traits

A number of studies have demonstrated associations between sensation seeking traits and measures of impulsivity. This study examined contributions to the observed correlations between imupulsivity and sensation seeking traits. Fifty-seven pairs of identical and 49 pairs of fraternal twins who were reared apart and 90 individuals who also participated in the Minnesota Study of Twins Reared Apart completed the Control scale of the Multidimensional Personality Questionnaire (MPQ; Tellegen, 1982) and the four subscales of the Sensation Seeking Scale (SSS; Zuckerman, 1979). Consistent with previous studies, the Control scale was significantly correlated with the SSS. A Cholesky decomposition of the data indicated that the phenotypic correlations between the Control scale and the four subscales of the SSS were mediated almost entirely by genetic factors. In the final reduced model the proportion of the genetic variance of the Control scale in common with the SSS was estimated as 55%, and the rest of the genetic variance (45%) was attributed to the genetic variance specific to the Control scale. The results emphasize the importance of common biological mechanisms underlying associations between impulsivity and sensation seeking traits.

Isolation and characterization of pokeweed antiviral protein mutations in Saccharomyces cerevisiae: identification of residues important for toxicity

Pokeweed antiviral protein (PAP), a 29-kDa protein isolated from Phytolacca americana inhibits translation by catalytically removing a specific adenine residue from the 28S rRNA of eukaryotic ribosomes. PAP has potent antiviral activity against many plant and animal viruses, including human immunodeficiency virus. We describe here development of a positive selection system to isolate PAP mutants with reduced toxicity. In vitro translation in the presence or absence of microsomal membranes shows that PAP is synthesized as a precursor and undergoes at least two different proteolytic processing steps to generate mature PAP. The PAP cDNA was placed under control of the galactose-inducible GAL1 promoter and transformed into Saccharomyces cerevisiae. Induction of PAP expression was lethal to yeast. The PAP expression plasmid was mutagenized and plasmids encoding mutant PAP genes were identified by their failure to kill S. cerevisiae. A number of mutant alleles were sequenced. In one mutant, a point mutation at Glu-177 inactivated enzymatic function in vitro, suggesting that this glutamic acid residue is located at or near the catalytic site. Mutants with either point mutations near the N terminus or a nonsense mutation at residue 237 produced protein that was enzymatically active in vitro, suggesting that the toxicity of PAP is not due solely to enzymatic activity. Toxicity of PAP appears to be a multistep process that involves possibly different domains of the protein.

Unequal rate of monozygotic and like-sex dizygotic twin birth: evidence from the Minnesota Twin Family Study

It is generally believed that in Caucasian populations the rate of monozygotic (MZ) twinning is approximately equal to the rate of like-sex dizygotic (DZ) twinning so that representative samples of like-sex twins should contain approximately equal numbers of MZ and DZ twins. Recent evidence suggests, however, that the rate of DZ twinning in Caucasian populations has declined over the past 50 years so that there are now many more MZ than like-sex DZ twin births (Jeanneret and MacMahon, 1962; James, 1972; Mosteller et al., 1981; Doherty and Lancaster, 1986; Lykken et al., 1990). We report additional evidence of a higher rate of MZ than like-sex DZ twinning from Minnesota for the birth years 1971-1984. The convergence of evidence thus suggests that the observation of a greater number of MZ than DZ twins in a volunteer twin sample can no longer necessarily be taken as a sign of ascertainment bias.

Genetic influences on perceptions of childhood family environment: a reared apart twin study

This study estimates the extent to which heredity influences perceptions of childhood family environment in a sample of 58 monozygotic and 46 dizygotic pairs of adult twins who were reared apart. The measures used to assess family environments were the Family Environment Scale (FES) and Block Environmental Questionnaire (BEQ). A principal component factor analysis with a VARIMAX rotation of the FES and BEQ yielded 2 major factors--Support, and Organization and Cultural Orientation. Single and multiple indicator model-fitting techniques were applied to the reared apart twin data on the 2 factors. Perceived support in childhood family environments was fitted best by a model incorporating additive genetic and unshared environmental factors. Perceived organization was fitted most adequately by a model which includes only unshared environmental factors. Maximum-likelihood estimates of heritability from model-fitting analyses suggest that genetic factors explain 44% of the variance of perceptions of support dimension in childhood family environments.

A survival study of surgically treated lung cancer in Korea. Lung Cancer Surgical Study Group

Survival rate over a 5-year period were studied in a series of 658 proven primary lung cancer patients treated by thoracic surgeons at 8 institutes during the period from 1976 to 1987 in Korea. The study was designed as a multi-center cooperative work for the statistical analysis of the followup result. Clinical data of age, sex, morbidity, and staging of the tumor were assessed in 540 patients to evaluate their 5-year survival rates. Eventually, 405 resectable patients were analyzed by stage, cell type, surgical procedure, and TNM status. The 5-year actuarial survival rates by stage in the resectable group were: stage I 39.7%, II 30.6% III A 16.3%, III B 6.7%, and IV 0%. The 5-year survival rates by cell type were: squamous cell 31.9%, adenocarcinoma 21.2%, large cell 11%, and small cell 6%. The survival rates by surgical procedures were: lobectomy 30.7% and pneumonectomy 25.7%. The survival rates by TNM status in the operable group were: T1 34.7%, T2 26.8%, T3 7.5%, T4 5%; N1 23%, N2 10%, N3 3%; MO 21%, and M1 0%, respectively. The overall actuarial 5-year survival rate in the group of 405 resectable patients was 25.9%.