bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasmid partitioning and the spreading of P1 partition protein ParB
Authors: Rodionov Oleg , Yarmolinsky Michael 
Published: May 2004

SummaryBacterial plasmids of low copy number, P1 prophage among them, are actively partitioned to nascent daughter cells. The process is typically mediated by a pair of plasmid‐encoded proteins and a cis‐acting DNA site or cluster of sites, referred to as the plasmid centromere. P1 ParB protein, which binds to the P1 centromere (parS), can spread for several kilobases along flanking DNA. We argue that studies of mutant ParB that demonstrated a strong correlation between spreading capacity and the ability to engage in partitioning may be misleading, and describe here a critical test of the dependence of partitioning on the spreading of the wild‐type protein. Physical constraints imposed on the spreading of P1 ParB were found to have only a minor, but reproducible, effect on partitioning. We conclude that, whereas extensive ParB spreading is not required for partitioning, spreading may have an auxiliary role in the process.
The AberdeenChildren of the 1950scohort study: background, methods and follow‐up information on a new resource for the study of life course and intergenerational influences on health
Authors: Batty G. David , Morton Susan M. B. , Campbell Doris , Clark Heather , Smith George Davey , Hall Marison , Macintyre Sally , Leon David A. 
Published: May 2004

SummaryIn this paper we introduce and describe in detail an addition to the UK's population‐based resources for the investigation of biological and social influences on health across the life course and between generations: the AberdeenChildren of the 1950sstudy. We also provide an account of postwar Aberdeen when study members were growing up, report on findings of analyses of data from the original survey on which this study is based and its follow‐up, assess the strengths and limitations of the study, and outline current and future research directions.This cohort comprises individuals born in Aberdeen, Scotland (UK) between 1950 and 1956, and is derived from 15 thousand subjects who took part in the Aberdeen Child Development Survey, a cross‐sectional study of ‘mental subnormality’ (learning disability) in a population of all children who were attending Aberdeen primary schools in December 1962. Data collection included information on birthweight, gestational age, childhood height and weight, tests of cognition and behavioural disorder, and a range of multilevel socio‐economic indicators. In 1998 we began the process of revitalising this cohort (now termed the AberdeenChildren of the 1950sstudy). We have been successful in ascertaining the current vital status and whereabouts of 98.5% of a target population of 12 150 subjects (6276 males, 5874 females) with full baseline data. The large majority (81%) of study participants still reside in Scotland and many (73%) have remained in the Grampian region which incorporates Aberdeen. At the present time, a total of almost 500 subjects are known to have died. Linkages to hospital admissions and other health endpoints captured through the Scottish Morbidity Records system have been completed. This includes an intergenerational linkage to approximately eight thousand deliveries in Scotland occurring to female members of the study population. A postal questionnaire to all traced surviving cohort members has also been distributed.
Impact of pregnancy‐induced hypertension on birthweight by gestational age
Authors: Xiong Xu , Fraser William D. 
Published: May 2004

SummaryFew studies to date have examined the effect of severe pre‐eclampsia, pre‐eclampsia, and gestational hypertension on birthweight according to gestational age. We conducted a population‐based retrospective cohort study of 16 936 pregnant women in Suzhou, China. Analysis of variance and multivariable linear regression were performed to compare the mean birthweights of babies born to mothers with gestational hypertension, pre‐eclampsia, and severe pre‐eclampsia with birthweights of infants born to mothers with normal blood pressure at each week of gestation.The differences in mean birthweight between women with severe pre‐eclampsia and women with normal blood pressure ranged between −467.7 g and 189.1 g. The birthweights were statistically significantly lower in women with severe pre‐eclampsia than in women with normal blood pressure for gestational age categories ≤ 35 and 36 weeks. However, after adjustment for confounding variables, the birthweights were not statistically significantly different in women with severe pre‐eclampsia when compared with women with normal blood pressure even at ≤ 35 and 36 weeks. The differences in mean birthweight between women with pre‐eclampsia and women with normal blood pressure ranged between −132.2 g and 174.6 g. These differences were not statistically significant, before or after adjusting for confounding variables. There were no differences in mean birthweight between women with gestational hypertension and women with normal blood pressure.Further analysis suggested that pre‐eclampsia and gestational hypertension were associated with increased rates of both small‐for‐gestational‐age and large‐for‐gestational‐age infants. The majority of the babies born to mothers with different types of pregnancy‐induced hypertension were appropriate‐for‐gestational‐age or even large‐for‐gestational‐ age.  In  this  Chinese  population,  most  babies  born  to  mothers with severe pre‐eclampsia or pre‐eclampsia and gestational hypertension had similar fetal growth to those born to normotensive mothers.
Parental exposure to medical radiation and neuroblastoma in offspring
Authors: Patton Tara , Olshan Andrew F. , Neglia Joseph P. , Castleberry Robert P. , Smith Joanna 
Published: May 2004

SummaryPrevious studies have suggested an association between parental medical radiation exposure and increased incidence of certain childhood cancers. We investigated the relationship between medical radiation and risk of neuroblastoma in offspring using data from a North American case–control study. Cases were children diagnosed with neuroblastoma from 1 May 1992, to 30 April 1994, at Children's Cancer Group and Pediatric Oncology Group institutions throughout the United States and Canada. One matched control per case was selected using random‐digit dialling. Telephone interviews were conducted with parents to collect data on any medical radiation examinations and treatments in the 2 years before conception or during pregnancy. We included 500 maternal and 339 paternal matched pairs. Overall, no association was found between maternal exposure to radiation and neuroblastoma risk (odds ratio [OR] = 1.0; 95% confidence interval [CI]: 0.7, 1.3). Analysis of maternal exposure by specific anatomical site showed no association for gonadal sites [OR = 1.0; 95% CI = 0.5, 2.0]. Little association was found with paternal radiation exposure [OR = 1.2; 95% CI = 0.8, 1.8]. No consistent exposure‐response gradient was found based upon the number of maternal or paternal medical radiation examinations. The data presented here, coupled with the lower radiation doses currently used, indicate that any further study of this question will require larger studies with improved exposure assessment.
Recent decelerated decline in perinatal mortality rate of unlike‐sexed twins in Japan
Authors: Kato Noriko 
Published: May 2004

SummaryThe effect of assisted reproductive technology is more pronounced in unlike‐sexed twins than in like‐sexed. Trends in perinatal mortality of twins were compared between the two types of sex combination. Certificates for births (478 276 cases), stillbirths (50 542 cases), and early neonatal deaths (8747 cases) were the subjects of this analysis. Since 1984, the decline in the perinatal mortality of unlike‐sexed twins has been slower than that of like‐sexed twins. In both light‐for‐dates (LFD) and non‐LFD, the decline in the gestational age standardised mortality ratio has been slower in unlike‐sexed twins. We suggest this is due to the introduction of assisted reproductive technologies.
Parental growth at different life stages and offspring birthweight: an intergenerational cohort study
Authors: Hyppönen Elina , Power Chris , Smith George Davey 
Published: May 2004

SummaryUsing three generations of the 1958 British national birth cohort we investigated ways in which parental size is related to offspring birthweight. By age 41 years, 4566 singleton female and 4050 male cohort members (born 3–9 March, 1958) had become parents and provided information on their singleton offspring.Mother's birthweight (standardised for gestational age and sex) was the strongest determinant of offspring birthweight (effect size [ES] per SDS 112 g [95% CI 97, 128]), which was little affected by adjustment for maternal height or BMI (ES 95 g and 105 g respectively). The intergenerational birthweight association was not observed for mothers born very small or large. Mother's childhood height at age 7 (ES 46 g [24, 67]), but not BMI (ES 3 g [−18, 23]), was associated with offspring birthweight after adjustment for grandparental size, own birthweight, and adult size. Controlling for other growth measures strongly attenuated the association between mother's adult height and offspring birthweight: (ES 90 g, unadjusted, and 25 g, adjusted), while the association between adult BMI and offspring birthweight was little affected (ES 55 g and 51 g respectively). Father's BMI did not affect offspring birthweight, while the associations for height were similar, albeit weaker, than those observed for the mother. Our results suggest that intergenerational associations in birthweights are largely independent of postnatal size. Maternal height in childhood was positively related to offspring birthweight, while the effect of her BMI was restricted to adulthood.
Maternal obesity as an independent risk factor for caesarean delivery
Authors: Sheiner Eyal , Levy Amalia , Menes Tehillah S. , Silverberg Daniel , Katz Miriam , Mazor Moshe 
Published: May 2004

SummaryThe present study was aimed to investigate pregnancy outcome among obese women and specifically the correlation between maternal obesity and incidence of caesarean section (CS) while controlling for the potential confounding effects of other variables associated with obesity. A population‐based study was performed comparing all pregnancies of obese (maternal pre‐pregnancy body mass index (BMI) of 30 kg/m2 or more) and non‐obese patients, between the years 1988 and 2002. Patients with hypertensive disorders and diabetes mellitus as well as patients lacking prenatal care were excluded from the analysis. Stratified analyses, using the Mantel‐Haenszel technique, and a multiple logistic regression model were performed to control for confounders. During the study period there were 126 080 deliveries meeting the inclusion criteria, of which 1769 (1.4%) occurred in obese patients.Using a multivariable analysis, the following conditions were significantly associated with maternal obesity: failure to progress during the first stage (odds ratio (OR) = 3.1; 95% confidence interval [CI] 2.5, 3.8; P < 0.001), fertility treatments (OR = 2.0; [95% CI 1.6, 2.5]; P < 0.001), previous CS (OR = 1.7; [95% CI 1.5, 1.9]; P < 0.001), malpresentations (OR = 1.4; [95% CI 1.2, 1.6]; P < 0.001), recurrent miscarriages (OR = 1.4; [95% CI 1.2, 1.7]; P < 0.001) and fetal macrosomia (OR = 1.4; [95% CI 1.2, 1.7]; P < 0.001). Higher rates of caesarean deliveries were found among obese parturients (27.8% vs. 10.8%; OR = 3.2; [95% CI 2.9, 3.5]; P < 0.001). When controlling for possible confounders, using the Mantel‐Haenszel technique, the association between maternal obesity and CS remained significant. No significant differences were noted between the groups regarding perinatal complications such as perinatal mortality, congenital malformations, shoulder dystocia and low Apgar scores.In conclusion, a significant association was found between obesity and CS even after the exclusion of hypertensive disorders and diabetes mellitus. Importantly, obesity alone was not associated with adverse perinatal outcome. Obstetricians should be encouraged to allow obese patients not suffering from diabetes or hypertensive disorders an adequate trial of labour.
Early discharge: no evidence of adverse outcomes in three consecutive population‐based Australian surveys of recent mothers, conducted in 1989, 1994 and 2000
Authors: Brown Stephanie , Bruinsma Fiona , Darcy Mary‐Ann , Small Rhonda , Lumley Judith 
Published: May 2004

SummaryLength of postnatal hospital stay has declined dramatically since the 1970s, with ongoing controversy about potential harmful effects. Three population‐based surveys of recent mothers conducted in the State of Victoria, Australia have been analysed to assess the impact of shorter length of stay on breast feeding and women's psychological well‐being. Women giving birth in Victoria, Australia in 1 week in 1989, 2 weeks in 1993 and 2 weeks in 1999, excluding those who had a stillbirth or neonatal death, were mailed surveys 5–8 months postpartum. Adjusted response fractions were: 71.4% in 1989 (n = 790), 62.5% in 1994 (n = 1313), and 67% in 2000 (n = 1616). Participants were representative in terms of method of birth, parity and infant birthweight. Younger women, single women and women of non‐English‐speaking background (born outside Australia) were under‐represented.The primary outcome measures were infant feeding at 6 weeks postpartum and maternal depression at 5–8 months postpartum (Edinburgh Postnatal Depression Scale ≥ 13). There was no significant association between length of stay (1–2 days vs. ≥ 5 days, 3–4 days vs. ≥ 5 days) and primary outcome measures in univariable analyses of the 1989 Survey, or multivariable analyses of the 1994 and 2000 Surveys adjusting for relevant social and obstetric factors. For stays of 3–4 days, the adjusted odds ratio for formula feeding at 6 weeks was 1.35 [95% CI 0.9, 1.9] in 1994 and 1.22 [95% CI 0.9, 1.7] in 2000. The confidence intervals are compatible with a very small reduction or a large increase in formula feeding, neither reaching statistical significance. For depressive symptoms at 5–7 months postpartum (EPDS score ≥ 13), the adjusted odds ratio for women staying 3–4 days was 0.96 [95% CI 0.7, 1.4] in 1994 and 0.90 [95% CI 0.6, 1.3] in 2000. These confidence intervals are compatible with a 30–40% reduction or a 30–40% increase in odds of depressive symptoms. Based on these findings shorter length of stay does not appear to have an adverse impact on breast feeding or women's emotional well‐being. Testing early discharge policies in well‐designed randomised trials remains a priority for developing stronger evidence to inform practice.
Cerebral palsy of post‐neonatal origin: characteristics and risk factors
Authors: Cans Christine , McManus Vicki , Crowley Michael , Guillem Pascale , Platt Mary‐Jane , Johnson Ann , Arnaud Catherine ,   SCPE (Surveillance of Cerebral Palsy in Europe) collaborative group
Published: May 2004

SummaryWe aimed to study the rates and trends over time of children with cerebral palsy (CP) of post‐neonatal origin (arising more than 28 days after birth, and before the age of 25 months), to examine their aetiology and associated significant risk factors, and to compare them with other CP cases. Children with post‐neonatal CP born 1976–90 were identified from a European database and seven registers were included (Surveillance of Cerebral Palsy in Europe collaboration). Using a previously published classification it was possible to allocate an aetiology to 99% of cases. The prevalence rate of post‐neonatal CP was 1.26 per 10 000 live births and a significant decrease was observed over the period 1976–90 (P = 0.011). Infection accounted for 50%, vascular episodes for 20% and head injury for 18% of the cases. Although there has been little change in the profile of underlying causes in this period, within the infection group, a significant downward trend was observed for Reye's syndrome (P < 0.001) and non‐central nervous system (non‐CNS) infection (P = 0.004), but not for meningitis/encephalitis. There was evidence of some increased risk of post‐neonatal CP among children with low birthweight (<2500 g) (P < 0.001). Overall children with CP of post‐neonatal origin showed a more severe functional pattern than non‐post‐neonatal CP children. In order to ascertain the impact of public health and other preventive measures aimed at reducing the frequency of brain injury in the first 2 years after birth, it is necessary to continue to monitor the frequency and characteristics of children with post‐neonatal CP into the 1990s.
Transcriptome of Arabidopsis leaf senescence
Authors: GUO Y. , CAI Z. , GAN S. 
Published: May 2004

AbstractLeaf senescence is a complex developmental process during which essential nutrients are recycled. In order to unravel the biochemical pathways and regulatory mechanisms that underlie this process, it would be valuable to examine the transcriptome associated with leaf senescence. Accordingly, an Arabidopsis thaliana leaf senescence cDNA library with approximately 104 recombinant clones was subjected to large‐scale single‐pass sequencing. Approximately 6200 expressed sequence tags (ESTs) were obtained, corresponding to 2491 unique genes. These included 134 genes encoding transcription factors and 182 genes whose products are components of signal transduction pathways, such as the mitogen‐activated protein kinase (MAPK) cascades. A total of 116 of these genes are predicted to be involved in protein turnover, including 75 genes associated with the ubiquitin–proteasome pathway and 35 proteinases. Many of the genes are predicted to encode transporters for ions, amino acids and sugars, consistent with the substantial nutrient recycling during leaf senescence. In addition, this study revealed ESTs for 98 annotated genes for which ESTs did not previously exist and 46 novel transcribed units that have not previously been annotated in the Arabidopsis genome. Approximately one‐third of the 2491 genes are predicted to encode proteins with unknown functions. The genes are distributed evenly on the five chromosomes.
Whole tree xylem sap flow responses to multiple environmental variables in a wet tropical forest
Authors: O'BRIEN J. J. , OBERBAUER S. F. , CLARK D. B. 
Published: May 2004

ABSTRACTIn order to quantify and characterize the variance in rainforest tree physiology, whole tree sap flow responses to local environmental conditions were investigated in 10 species of trees with diverse traits at La Selva Biological Station, Costa Rica. A simple model was developed to predict tree sap flow responses to a synthetic environmental variable generated by a principle components analysis. The best fit was obtained with a sigmoid function which explained between 74 and 93% of the variation in sap flux of individual trees. Sap flow reached an asymptote where higher light and evaporative demand did not cause sap flux to increase further. Soil moisture had little influence on sap flux. The morphological characteristics of the trees significantly affected sap flow; taller trees responded to changes in environmental variables sooner than shorter trees and high liana cover buffered tree sap flow responses to weather. The effect of species‐specific differences on the model was small; the mean effectiveness of the model was reduced by 6% when parameters were estimated from a single pool of measurements taken from all individuals. The results indicate that sap flow response could be effectively estimated using a simple general model and composite environmental index for these 10 diverse tree species.
Canopy gradients in leaf intercellular CO2 mole fractions revisited: interactions between leaf irradiance and water stress need consideration
Authors: NIINEMETS Ü. , SONNINEN E. , TOBIAS M. 
Published: May 2004

ABSTRACTIntercellular CO2 mole fractions (Ci) are lower in the upper canopy relative to the lower canopy leaves. This canopy gradient in Ci has been associated with enhanced rates of carbon assimilation at high light, and concomitant greater draw‐downs in Ci. However, increases in irradiance in the canopy are generally also associated with decreases in leaf water availability. Thus, stress effects on photosynthesis rates (A) and stomatal conductance (G), may provide a further explanation for the observed Ci gradients. To test the hypotheses of the sources of canopy variation in Ci, and quantitatively assess the influence of within‐canopy differences in stomatal regulation on A, the seasonal and diurnal variation in G was studied in relation to seasonal average daily integrated quantum flux density (Qint) in tall shade‐intolerant Populus tremula L. trees. Daily time‐courses of A were simulated using the photosynthesis model of Farquhar et al. (Planta 149, 78–90, 1980). Stable carbon isotope composition of a leaf carbon fraction with rapid turnover rate was used to estimate canopy gradient in Ci during the simulations. Daily maximum G (Gmax) consistently increased with increasing Qint. However, canopy differences in Gmax decreased as soil water availability became limiting during the season. In water‐stressed leaves, there were strong mid‐day decreases in G that were poorly associated with vapour pressure deficits between the leaf and atmosphere, and the magnitude of the mid‐day decreases in G occasionally interacted with long‐term leaf light environment. Simulations indicated that the percentage of carbon lost due to mid‐day stomatal closure was of the order of 5–10%, and seasonal water stress increased this percentage up to 20%. The percentage of carbon lost due to stomatal closure increased with increasing Qint. Canopy differences in light environment resulted in a gradient of daily average Ci of approximately 20 µmol mol−1. The canopy variation in seasonal and diurnal reductions in G led to a Ci gradient of approximately 100 µmol mol−1, and the actual canopy Ci gradient was of the same magnitude according to leaf carbon isotope composition. This study demonstrates that stress effects influence Ci more strongly than within‐canopy light gradients, and also that leaves acclimated to different irradiance and water stress conditions may regulate water use largely independent of foliar photosynthetic potentials.
Hybridization of European oaks (Quercus ilex × Q. robur) results in a mixed isoprenoid emitter type
Authors: SCHNITZLER J.‐P. , STEINBRECHER R. , ZIMMER I. , STEIGNER D. , FLADUNG M. 
Published: May 2004

ABSTRACTEuropean oaks have been reported to emit isoprene or monoterpenes derived from recently fixed photosynthetic carbon. The emission type is plant species specific and can be used as chemo‐taxonomic marker. In the present article the isoprenoid biochemical properties of mature Quercus × turneri‘Pseudoturneri’ hybrids resulting from a crossing of a Mediterranean evergreen monoterpene‐emitting species (subgenus Sclerophyllodrys; Quercus ilex L.) and an isoprene‐emitting deciduous oak species (subgenus Lepidobalanus; Quercus robur L.) are described. Both species are compared with respect to the capacity for isoprenoid synthesis and the actual isoprenoid emission pattern of different tree‐types. The analysis showed that the oak hybrid combines properties of both parental species. Furthermore, it could be shown that the enzyme activities of isoprene synthase and monoterpene synthases are reflected in the isoprenoid emission pattern of the hybrids as well as in the observed emission rates.