bluuebunny/crossref_metadata_2025_split huggingface dataset:
United States vital statistics and the measurement of gestational age
Authors: Martin Joyce A. 
Published: September 2007

SummaryEstimates of the gestational age of the newborn based on US Birth Certificate data are extensively used to monitor trends in infant and maternal health and to improve our understanding of adverse pregnancy outcome. Two measures of gestational age, the ‘date of the last normal menses’ (LMP) and the ‘clinical estimate of gestation’ (CE), have been available from birth certificate data since 1989. Reporting irregularities with the LMP‐based measure are well‐documented, and important questions remain regarding the derivation of the CE. Changes in perinatal medicine and in vital statistics reporting in recent years may have importantly altered gestational age data based on vital statistics. This study describes how gestational age measures are collected and edited in US national vital statistics, and examines changes in the reporting of these measures by race and Hispanic origin between 1990 and 2002. Data are drawn from the National Center for Health Statistics' restricted use US birth files for 1990–2002. Bivariable statistics are used.The percentage of records with missing LMP dates declined markedly over the study period, overall, and for each racial/Hispanic origin group studied. A marked shift in the distribution of the CE of gestational age was also observed, suggesting changes both in the true distribution of age at birth, and in the derivation of this measure. Agreement between the LMP‐based and CE estimates increased over the study period, especially among preterm births. However, a high proportion of LMP dates continue to be missing or invalid and the derivation of the CE is still uncertain. In sum, although the reporting of gestational age measures in vital statistics appears to have improved between 1990 and 2002, substantial concerns with both the LMP‐based and the CE persist. Efforts to identify approaches to further improve upon the quality of these data are needed.
Gestational age estimates from singleton births conceived using assisted reproductive technology
Authors: Callaghan William M. , Schieve Laura A. , Dietz Patricia M. 
Published: September 2007

SummaryInformation on gestational age for public health research and surveillance in the US is usually obtained from vital records and is primarily based on the first day of the woman's last menstrual period (LMP). However, using LMP as a marker of conception is subject to a variety of errors and results in misclassification of gestational age. Pregnancies conceived through assisted reproductive technology (ART) are unique in that the estimates of gestational age are not based on the LMP, but on the date when fertilisation actually occurred, and thus most gestational age errors are likely to be due to errors introduced in recording and data entry. The purpose of this paper was to examine the birthweight distribution by gestational age for ART singleton livebirths reported to a national ART surveillance system. Gestational age was categorised as 20–27, 28–31, 32–36 and 37–44 weeks; birthweight distributions were plotted for each category. The distributions of very‐low‐birthweight (VLBW; <1500 g), moderately low‐birthweight (1500–2499 g) and normal‐birthweight infants for each gestational week were examined.At both 20–27 and 28–31 weeks, there was an extended right tail to the distribution and a small second mode. At 32–36 weeks, there were long tails in either direction and at 37–44 weeks, an extended tail to the left. There was a high proportion of VLBW infants at low gestational ages and a decreasing proportion of VLBW infants with increasing gestational age. However, there was also a fairly constant proportion of normal‐birthweight infants at every gestational age below 34 weeks, which suggested misclassification of gestational age. Approximately 12% of ART births classified as 28–31 weeks' gestation had a birthweight in the second mode of the birthweight distribution compared with approximately 29% in national vital statistics data. Even when the birthweight and dates of conception and birth are known, questions remain regarding the residual amount of misclassification and the true nature of the birthweight distributions.
The research implications of the selection of a gestational age estimation method
Authors: Lynch Courtney D. , Zhang Jun 
Published: September 2007

SummaryThere are three primary methods of gestational age estimation: dating based on last menstrual period (LMP), ultrasound‐based dating and neonatal estimates. We review the strengths and limitations of each method as well as their implications for research. Dating based on LMP is a simple, low‐cost method of estimating gestational age. Limitations associated with the use of menstrual‐based dating include reporting problems such as uncertainty regarding the LMP date, possibly due to bleeding not associated with menses, as well as concerns about the incidence of delayed ovulation, which can result in invalid estimates of gestation, even for women with certain LMP dates. Given that most women in the US have at least one ultrasound during pregnancy, it is becoming increasingly common for clinicians to verify menstrual dates using early ultrasound. To calculate gestational age with the use of ultrasound, fetal measurements are compared with a gestational age‐specific reference. The primary limitation of this method is the fact that the gestational age estimates of symmetrically large or small fetuses will be biased. Further, given that ultrasound references were developed using pregnancies that were dated according to reliable LMP dates, they are potentially biased in the same direction as dates calculated according to LMP. Neonatal estimates of gestational age have been shown to be the least precise dating method. To highlight the research implications of the choice of a gestational dating method, we used data from the Routine Antenatal Diagnostic Imaging with Ultrasound Study to identify risk factors for post‐term delivery. Risk factors for post‐term delivery are shown to vary according to the choice of a gestational dating method, suggesting that some findings are an artefact of the choice of a method rather than evidence of causality.
Multiple imputation for national public‐use datasets and its possible application for gestational age in United States Natality files
Authors: Parker Jennifer D. , Schenker Nathaniel 
Published: September 2007

SummaryMultiple imputation (MI) is a technique that can be used for handling missing data in a public‐use dataset. With MI, two or more completed versions of the dataset are created, containing possibly different but reasonable replacements for the missing data. Users analyse the completed datasets separately with standard techniques and then combine the results using simple formulae in a way that allows the extra uncertainty due to missing data to be assessed. An advantage of this approach is that the resulting public‐use data can be analysed by a variety of users for a variety of purposes, without each user needing to devise a method to deal with the missing data. A recent example for a large public‐use dataset is the MI of the family income and personal earnings variables in the National Health Interview Survey. We propose an approach to utilise MI to handle the problems of missing gestational ages and implausible birthweight–gestational age combinations in national vital statistics datasets. This paper describes MI and gives examples of MI for public‐use datasets, summarises methods that have been used for identifying implausible gestational age values on birth records, and combines these ideas by setting forth scenarios for identifying and then imputing missing and implausible gestational age values multiple times. Because missing and implausible gestational age values are not missing completely at random, using multiple imputations and, thus, incorporating both the existing relationships among the variables and the uncertainty added from the imputation, may lead to more valid inferences in some analytical studies than simply excluding birth records with inadequate data.
Evolutionary dynamics of an ancient retrotransposon family provides insights into evolution of genome size in the genusOryza
Authors: Ammiraju Jetty S. S. , Zuccolo Andrea , Yu Yeisoo , Song Xiang , Piegu Benoit , Chevalier Frederic , Walling Jason G. , Ma Jianxin , Talag Jayson , Brar Darshan S. , SanMiguel Phillip J. , Jiang Ning , Jackson Scott A. , Panaud Olivier , Wing Rod A. 
Published: September 2007

SummaryLong terminal repeat (LTR) retrotransposons constitute a significant portion of most eukaryote genomes and can dramatically change genome size and organization. Although LTR retrotransposon content variation is well documented, the dynamics of genomic flux caused by their activity are poorly understood on an evolutionary time scale. This is primarily because of the lack of an experimental system composed of closely related species whose divergence times are within the limits of the ability to detect ancestrally related retrotransposons. The genusOryza, with 24 species, ten genome types, different ploidy levels and over threefold genome size variation, constitutes an ideal experimental system to explore genus‐level transposon dynamics. Here we present data on the discovery and characterization of an LTR retrotransposon family namedRWGin the genusOryza. Comparative analysis of transposon content (approximately 20 to 27 000 copies) and transpositional history of this family across the genus revealed a broad spectrum of independent and lineage‐specific changes that have implications for the evolution of genome size and organization. In particular, we provide evidence that the basal GG genome ofOryza(O. granulata) has expanded by nearly 25% by a burst of theRWGlineageGran3subsequent to speciation. Finally we describe the recent evolutionary origin ofDasheng, a large retrotransposon derivative of theRWGfamily, specifically found in the A, B and C genome lineages ofOryza.
Global gene expression analysis of the shoot apical meristem of maize (Zea mays L.)
Authors: Ohtsu Kazuhiro , Smith Marianne B. , Emrich Scott J. , Borsuk Lisa A. , Zhou Ruilian , Chen Tianle , Zhang Xiaolan , Timmermans Marja C. P. , Beck Jon , Buckner Brent , Janick‐Buckner Diane , Nettleton Dan , Scanlon Michael J. , Schnable Patrick S. 
Published: September 2007

SummaryAll above‐ground plant organs are derived from shoot apical meristems (SAMs). Global analyses of gene expression were conducted on maize (Zea mays L.) SAMs to identify genes preferentially expressed in the SAM. The SAMs were collected from 14‐day‐old B73 seedlings via laser capture microdissection (LCM). The RNA samples extracted from LCM‐collected SAMs and from seedlings were hybridized to microarrays spotted with 37 660 maize cDNAs. Approximately 30% (10 816) of these cDNAs were prepared as part of this study from manually dissected B73 maize apices. Over 5000 expressed sequence tags (ESTs) (about 13% of the total) were differentially expressed (P < 0.0001) between SAMs and seedlings. Of these, 2783 and 2248 ESTs were up‐ and down‐regulated in the SAM, respectively. The expression in the SAM of several of the differentially expressed ESTs was validated via quantitative RT‐PCR and/or in situ hybridization. The up‐regulated ESTs included many regulatory genes including transcription factors, chromatin remodeling factors and components of the gene‐silencing machinery, as well as about 900 genes with unknown functions. Surprisingly, transcripts that hybridized to 62 retrotransposon‐related cDNAs were also substantially up‐regulated in the SAM. Complementary DNAs derived from the LCM‐collected SAMs were sequenced to identify additional genes that are expressed in the SAM. This generated around 550 000 ESTs (454‐SAM ESTs) from two genotypes. Consistent with the microarray results, approximately 14% of the 454‐SAM ESTs from B73 were retrotransposon‐related. Possible roles of genes that are preferentially expressed in the SAM are discussed.
Phosphorylation of threonine 161 in plant cyclin‐dependent kinase A is required for cell division by activation of its associated kinase
Authors: Harashima Hirofumi , Shinmyo Atsuhiko , Sekine Masami 
Published: September 2007

SummaryAlthough A‐type cyclin‐dependent kinase A (CDKA) is required for plant cell division, our understanding of how CDKA is activated before the onset of commitment to cell division is limited. Here we show that phosphorylation of threonine 161 (T161) in plant CDKA is required for activation of its associated kinase. Western blot analysis revealed that phosphorylation of CDKA T161 increased greatly, in parallel with activation of p13suc1‐associated kinase activity, when stationary‐phase tobacco BY‐2 cells were subcultured into fresh medium. Although induced over‐expression of a dominant‐negative CDKA mutant (D146N) fused with green fluorescent protein (GFP) in BY‐2 cells resulted in elongated cells after cell division was arrested, over‐expression of this CDKA mutant with a non‐phosphorylatable alanine in place of T161 (T161A) had no effect on cellular growth. However, immunoprecipitates of both GFP‐fused CDKAs exhibited virtually no histone H1 kinase activity, suggesting that both mutants formed kinase‐inactive complexes. In a baculovirus expression system, the recombinant CDKA(T161A)/cyclin D complex possessed no detectable kinase activity, indicating that phosphorylation of T161 is required for CDKA activation. To further elucidate the role of T161 phosphorylation, we used a loss‐of‐function mutation in the CDKA;1 gene, which encodes the only Arabidopsis CDKA. This mutant displays male gametophyte lethality, and produces bicellular pollen grains instead of the tricellular grains produced in wild‐type plants. Introduction of CDKA;1(T161E)–GFP, which mimics phosphorylated T161, resulted in successful complementation of the cdka‐1 mutation, whereas no recovery was observed when CDKA;1(T161A)–GFP was introduced. Thus, phosphorylation of T161 in Arabidopsis CDKA;1 is essential for cell division during male gametogenesis.
Postoperative intraperitoneal adhesion pathophysiology
Authors: Duron J‐J. 
Published: September 2007

AbstractAside from the normal ‘ad integrum’ peritoneal regeneration, the postoperative intraperitoneal adhesion formation process may be considered as the pathological part of peritoneal healing following any injury, particularly a surgical one. Despite a large body of clinical and experimental studies, its pathophysiology remains controversial. Moreover, a better understanding of the pathophysiological events and of the medical and surgical factors involved in the adhesion formation process is pivotal in any attempt to control this very frequent phenomenon and its serious consequences.
Impact of adhesions in colorectal surgery
Authors: Bhardwaj R. , Parker M. C. 
Published: September 2007

AbstractThe extent of the problem of adhesions is considerable and poses a significant burden on healthcare systems, the workload of surgeons and the lives of patients. This paper reviews the work undertaken and the associated evidence for the impact of adhesions. It considers the various options and strategies to reduce adhesions alongside the fundamental necessity for good surgical technique.
Consequences and complications of peritoneal adhesions
Authors: Van Goor H. 
Published: September 2007

AbstractConsequences and complications of postsurgical intra‐abdominal adhesion formation not including small bowel obstruction and secondary infertility are substantial but are under‐exposed in the literature. Inadvertent enterotomy during reopening of the abdomen or subsequent adhesion dissection is a feared complication of surgery after previous laparotomy. The incidence can be as high as 20% in open surgery and between 1% and 100% in laparoscopy depending on the underlying disease. Delayed postoperative detection of enterotomy is a particular feature of laparoscopy associated with significant morbidity and mortality. Adhesions to the ventral abdominal wall are responsible for the majority of trocar injuries. Both trocar injuries and inadvertent enterotomies result in conversion from laparoscopy to laparotomy in almost 100% of cases. There is a paucity of data on other organ injury, such as liver laceration or bladder perforation. Dissecting adhesions before executing the planned operation takes on average 20 min, being one‐fifth of the total operating time in patients having had previous open colorectal surgery. There is some evidence that postoperative morbidity and mortality of patients who need adhesiolysis is higher than that of patients with a virgin abdomen. The necessity to dissect adhesions is associated with increased hospital stay. Postsurgical adhesions are considered a main reason for conversion from laparoscopy to laparotomy in many types of procedures including laparoscopic colonic resection. Adhesion formation is part of the innate peritoneal defence mechanism in peritonitis. Abscess formation and bleeding, organ injury and fistula formation at ‘on demand’ relaparotomies are well‐known complications after surgery for intra‐abdominal sepsis associated with fibrinous adhesions. The clinical magnitude hereof is poorly researched. Postsurgical adhesions may cause pain as evidenced by pain mapping clinical experiments. Filmy adhesions between movable organs and the peritoneum appear to be worse in terms of generating pain. The high caseload of gynaecological and some colorectal practices suggest an enormous impact of adhesion‐related chronic abdominal and pelvic pain on patient’s wellbeing and socio‐economic costs. The significant risk of inadvertent enterotomy, conversion to laparotomy and trocar injury, and the associated postoperative morbidity and mortality and increased length of hospital stay warrant routine informed consent of adhesiolysis related complications in patients scheduled for abdominal or pelvic reoperation.
Practicalities and costs of adhesions
Authors: Wilson M. S. 
Published: September 2007

AbstractIn spite of postoperative adhesions being common there appears to be a reluctance to use anti‐adhesion products routinely.This article compares the incidence of adhesions with other conditions in order to identify the level of risk. The health economics surrounding adhesion‐related disease are described. This combined information may be of help to convince health practitioners of the need to take a more active role in adhesion prevention.The SCAR project has identified the risk of adhesion‐related disease. This is compared with published risks of other common clinical situations. An economic model first described by the author in 2002 has been revised with 2006 costs [1]. The SCAR data demonstrates a directly related risk of re‐admission in certain groups of 9.4% over 5 years [2]. The frequency of including this fact in the consenting process is low (<15%) [3]. Legal precedent has identified a risk of >2% warrants inclusion in the consent process; failure to do so could be considered negligent [4]. Use of an anti‐adhesion product with a cost of 130 euros with an efficacy of 25% in 1 year in the UK could save over 40 million euros over a 10‐year period.Adhesion risk is frequent enough to include in consent. Failure to do this and avoidance of treatment, which may reduce adhesions will have major financial consequences on healthcare systems.
Learning to be Palestinian in Athens: constructing national identities in diaspora
Authors: MAVROUDI ELIZABETH 
Published: September 2007

AbstractIn this article I focus on constructions of diasporic national identities and the nation as active and strategic processes using the case study of Palestinians in Athens. I seek, thereby, to contribute to debates on national identity, the nation and long‐distance nationalism, particularly in relation to those in diaspora with a collective cause to advocate. I explore how first‐ and second‐generation Palestinians in Athens construct and narrate Palestinian national identities, the homeland and political unity. I argue that the need to ‘choose’ to be Palestinian, often for political reasons, highlights that the nation is not a ‘given’ entity. This can be a difficult process for those in diaspora to deal with, as there may be tensions between constructions of political unity and attachment to the homeland and feelings of ambivalence and in‐between‐ness that may be seen as politically counterproductive. However, I stress that ‘messy’ and contradictory narratives and spatialities of diasporic national identities that come about as a result of cross‐border or transnational (dis)connections do not necessarily lead to apathy and, therefore, can be important.
PERMANENT GENETIC RESOURCES: Characterization of microsatellite markers for the almendro (Dipteryx panamensis), a tetraploid rainforest tree
Authors: HANSON THOR R. , BRUNSFELD STEVEN J. , FINEGAN BRYAN , WAITS LISETTE P. 
Published: September 2007

AbstractThe almendro (Dipteryx panamensis, Fabaceae) is a tetraploid tree native to the Atlantic lowland rainforests of Central America. We present nine microsatellite primer pairs amplified in three multiplexed reactions for 549 individuals from four sites in Costa Rica. All loci were polymorphic, ranging from three to 13 alleles per locus. Expected heterozygosity was estimated with the program tetrasat, and ranged from 0.21 to 0.74 across loci. These markers will be used for estimating pollen dispersal, seed dispersal, genetic structure and genetic diversity in fragmented landscapes.
Weak blood group B phenotypes may be caused by variations in the CCAAT‐binding factor/NF‐Y enhancer region of the ABO gene
Authors: Seltsam Axel , Wagner Franz F. , Grüger Daniela , Gupta Christa D. , Bade‐Doeding Christina , Blasczyk Rainer 
Published: September 2007

BACKGROUND: Binding of CCAAT‐binding factor NF‐Y (CBF/NF‐Y) to a 43‐bp repeat unit in the minisatellite region in the 5′ region of the ABO gene (CBF/NF‐Y enhancer region) plays an important role in regulating the transcription of ABO genes. The common ABO alleles were found to have CBF/NF‐Y enhancer regions with specific numbers of 43‐bp minisatellite repeats.MATERIAL AND METHODS: Blood samples from four healthy blood donors with weak B phenotypes were subjected to extensive ABO genotyping, including nucleotide sequencing of the 5′ regulatory region containing the CBF/NF‐Y enhancer.RESULTS: The coding region of the ABO genes exhibited common ABO*B101‐heterozygous genotypes in all samples, but unexpected variations were observed in the CBF/NF‐Y enhancer region. In two cases, the CBF/NF‐Y enhancer motifs did not exhibit the expected ABO allele dependency. One, an ABweak sample was heterozygous for ABO*A101 and ABO*B101 but homozygous for the ABO*B101‐specific CBF/NF‐Y motif. The second had a common ABO*B101/ABO*O01 genotype but was heterozygous for ABO*A101‐ and ABO*O01‐specific enhancer motifs. In the other two samples, novel CBF/NF‐Y motifs were found. One contained a shortened version of an otherwise ABO*B101‐specific CBF/NF‐Y motif, and the other had a single‐base substitution located 12 bp upstream from the beginning of the first 43‐bp repeat of an ABO*B101‐specific CBF/NF‐Y enhancer sequence.CONCLUSION: The frequency of variations in the CBF/NF‐Y region of the ABO gene in these samples with presumably common ABO*B101 alleles suggests that weak blood group B phenotypes may be caused by sequence variations in the CBF/NF‐Y regulatory region.