bluuebunny/crossref_metadata_2025_split huggingface dataset:
A prospective longitudinal study of growth velocity in twin pregnancy
Authors: Smith A. P. M. , Ong S. , Smith N. C. S. , Campbell D. 
Published: March 2003

AbstractObjectivesFundamental research into the growth of twins is lacking. Twin growth in utero is commonly assumed to follow similar patterns of growth as that of singletons. This preliminary descriptive study on twin pregnancy aimed to define growth velocity as gestation advances, and to study if twin order, fetal sex, zygosity and chorionicity have any relationship to growth velocity.MethodsOne hundred and sixty‐two women with twin pregnancies had an ultrasound examination at fortnightly intervals from 16 weeks until delivery. Fetal measurements of biparietal diameter, abdominal circumference and femur length were performed at each examination. Growth velocity for each parameter was defined as the difference in measurements for that parameter divided by the time interval between measurements. Postnatally, zygosity and chorionicity were determined by genetic fingerprinting and inspection of the placenta, respectively.ResultsGrowth velocity for all parameters decreased as gest‐ation advanced, with the downward trend more noticeable after 32 weeks. Maximum and minimum growth occurred at 22–23 weeks and 36–37 weeks, respectively. Maximum and minimum growth velocities for the abdominal circumference were 1.7 and 0.8 cm/week, respectively. Birth order, fetal sex, chorionicity and zygosity were not related to growth velocity.ConclusionsThese preliminary results suggest that growth velocity in twins decreases after 32 weeks' gestation. It appears that growth velocity is independent of birth order, fetal sex, chorionicity and zygosity. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
A comparison of sonographic cervical parameters in predicting spontaneous preterm birth in high‐risk singleton gestations
Authors: Guzman E. R. , Walters C. , Ananth C. V. , O'Reilly‐Green C. , Benito C. W. , Palermo A. , Vintzileos A. M. 
Published: March 2003

AbstractObjectivesTo assess the role of cervical sonography and to compare various sonographic cervical parameters in their ability to predict spontaneous preterm birth in high‐risk singleton gestations.DesignA prospective cohort of 469 high‐risk gestations were longitudinally evaluated between 15 and 24 weeks' gestation on 1265 occasions with transvaginal cervical sonography and transfundal pressure. The cervical parameters obtained were funnel width and length, cervical length, percent funneling and cervical index. The information obtained was used for patient management. Restriction of physical activities was initiated at cervical lengths of ≤ 2.5 cm with cerclage as an option for cervical lengths of ≤ 2.0 cm.ResultsReceiver operating characteristic curve analyses showed that a cervical length of ≤ 2.5 cm between 15 and 24 weeks' gestation was equal to the other sonographic cervical parameters in its ability to predict spontaneous preterm birth. The sensitivities for delivery at < 28, < 30, < 32 and < 34 weeks' gestation were 94%, 91%, 83% and 76%, respectively, while the negative predictive values were 99%, 99%, 98% and 96%, respectively. The placement of a cerclage did not influence the positive and negative predictive values. In comparison to women with other risk factors, cervical length was best in the prediction of preterm birth in women with a prior mid‐trimester loss; an optimal cut‐off of ≤ 1.5 cm had sensitivities for delivery at < 28, < 30, < 32 and < 34 weeks' gestation of 100%, 100% 92% and 81%, respectively. The rate of preterm delivery at < 34 weeks' gestation increased dramatically when the cervical length was ≤ 1.5 cm. Cervical length was the only independent variable that entered the logistic regression model for the prediction of preterm delivery at < 34 weeks' gestation.ConclusionsIn high‐risk singleton gestations a cervical length of ≤ 2.5 cm was equal to other sonographic cervical parameters in its ability to predict spontaneous preterm birth and was better for the prediction of earlier forms of prematurity (at < 28 and < 30 weeks) than later forms (at < 32 and < 34 weeks). The optimal cervical lengths and their performance for predicting prematurity may be influenced by obstetric risk factors. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Maternal left ventricular mass and diastolic function during pregnancy
Authors: Kametas N. A. , McAuliffe F. , Hancock J. , Chambers J. , Nicolaides K. H. 
Published: March 2003

AbstractObjectiveTo evaluate changes in left ventricular mass and diastolic function during normal pregnancy.MethodsThis was a cross‐sectional study of 125 pregnant women at 9–42 weeks of gestation and 19 non‐pregnant female controls. Two‐dimensional and M‐mode echocardiography of the maternal left ventricle and left atrium was performed.ResultsDuring pregnancy left ventricular mass increased by 52%. There was an increase in left ventricular end‐diastolic and end‐systolic diameters (12% and 20%, respectively), left ventricular posterior wall diameter during diastole and systole (22% and 13%, respectively) and left intraventricular septum during diastole and systole (15% and 19%, respectively). Mitral valve A‐wave maximum velocity increased during pregnancy by 19%, while mitral valve E‐wave maximum velocity and the ratio of E‐wave/A‐wave velocities increased early in pregnancy by about 14% and 6%, respectively, with a subsequent decline to 4% and 10%, respectively, below non‐pregnant levels.ConclusionLeft ventricular mass increases during pregnancy, while left ventricular diastolic function, as demonstrated by the changes in mitral valve flow velocities, increases in the first two trimesters but declines in the third trimester. Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Uterine artery Doppler and placental volume in the first trimester in the prediction of pregnancy complications
Authors: Schuchter K. , Metzenbauer M. , Hafner E. , Philipp K. 
Published: March 2003

AbstractObjectiveTo evaluate placental volume and uterine artery Doppler in the first trimester in the prediction of pregnancies that subsequently develop pre‐eclampsia, pregnancy‐induced hypertension, preterm placental abruption or fetal growth restriction.MethodsIn 380 singleton pregnancies attending our center for nuchal translucency screening at 11–14 weeks of gestation, Doppler assessment of both uterine arteries was carried out for measurement of the pulsatility index and the mean pulsatility index of the two vessels was calculated. In addition, three‐dimensional ultrasound was used to obtain images for subsequent measurement of placental volume. The 90th centile of the uterine artery mean pulsatility index and the 10th centile of the placental volume for crown–rump length (placental quotient) were calculated. These cut‐offs were used for the prediction of pregnancy complications.ResultsComplications occurred in 36 (9.5%) of the 380 pregnancies, including 31 cases of fetal growth restriction, two of pregnancy‐induced hypertension and abruption, two of pregnancy‐induced hypertension, and one of abruption. The uterine artery mean pulsatility index was ≥ 90th centile in 38 (10%) pregnancies and this group contained nine (25%) of those that developed complications. The placental quotient was ≤ 10th centile in 39 (10%) pregnancies and this group contained eight (22%) of those that developed complications. In eight (2%) pregnancies the uterine artery mean pulsatiltiy index was ≥ 90th centile and the placental quotient was ≤ 10th centile and this group contained six (17%) of those that developed complications.ConclusionThe combination of placental volume measurement and uterine artery Doppler in the first trimester may identify women at risk for subsequent development of pregnancy complications.Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Temporal sequence of abnormal Doppler changes in the peripheral and central circulatory systems of the severely growth‐restricted fetus
Authors: Ferrazzi E. , Bozzo M. , Rigano S. , Bellotti M. , Morabito A. , Pardi G. , Battaglia F. C. , Galan H. L. 
Published: March 2003

AbstractObjectiveTo identify the temporal sequence of abnormal Doppler changes in the fetal circulation in a subset of early and severely growth‐restricted fetuses.MethodsThis was a prospective observational study in a tertiary care/teaching hospital. Twenty‐six women who were diagnosed with growth‐restricted fetuses by local standards before 32 weeks' gestation and who had abnormal uterine and umbilical artery Doppler velocimetry were enrolled onto the study. To compare Doppler changes as a function of time, pulsed‐wave Doppler ultrasound was performed on five vessels in the fetal peripheral and central circulations. Doppler examinations were performed twice‐weekly and on the day of delivery if the fetal heart rate tracing became abnormal. Doppler indices were scored as abnormal when their values were outside the local reference limits on two or more consecutive measurements. Biometry for assessment of fetal growth was performed every 2 weeks. Computerized fetal heart rates were obtained daily. Delivery was based on a non‐reactive fetal heart rate tracing and not on Doppler information. Patients with a severely growth‐restricted fetus who were delivered for maternal indications such as pre‐eclampsia were excluded. Perinatal outcome endpoints included: intrauterine death, gestational age at delivery, newborn weight, central nervous system damage of grade 2 or greater, intraventricular hemorrhage and neonatal mortality.ResultsMean gestational age and newborn weight at delivery were 29 (standard deviation (SD), 2) weeks and 818 (SD, 150) g, respectively. The sequence of Doppler velocimetric changes was described by onset time cumulative curves that showed two time‐related events. First, for each vessel there was a progressive increase in the percent of fetuses developing a Doppler abnormality. Second, severely growth‐restricted fetuses followed a progressive sequence of acquiring Doppler abnormalities which were categorized into ‘early’ and ‘late’ Doppler changes. Early changes occurred in peripheral vessels (umbilical and middle cerebral arteries; 50% of patients affected 15–16 days prior to delivery). Late changes included umbilical artery reverse flow, and abnormal changes in the ductus venosus, aortic and pulmonary outflow tracts (50% of patients affected 4–5 days prior to delivery). The time interval between the occurrence of early and late changes was significantly different (P < 0.0001) and late changes were significantly associated with perinatal death (P < 0.01).ConclusionsDoppler velocimetry abnormalities develop in different vessels of the severely growth‐restricted fetus in a sequential fashion. Late changes in vascular adaptation by the severely growth‐restricted fetus are the best predictor of perinatal death. Copyright © 2002 ISUOG
Characterization of muscle actin genes in Drosophila virilis reveals significant molecular complexity in skeletal muscle types
Authors: Lovato T. L. , Meadows S. M. , Baker P. W. , Sparrow J. C. , Cripps R. M. 
Published: March 2003

AbstractActin is a ubiquitous and highly conserved eukaryotic protein required for cell motility and locomotion. In this manuscript, we characterize the four muscle actin genes of the insect Drosophila virilis and demonstrate strong similarities between the D. virilis genes and their homologues in Drosophila melanogaster; intron locations are conserved, and there are few amino acid differences between homologues. We also found strong conservation in temporal expression patterns of the muscle actin genes – the homologues of the D. melanogaster genes Act57B and Act87E are expressed throughout the life cycle, whereas the other two D. virilis genes, homologous to Act79B and Act88F are specific to pupal and adult stages. In situ hybridization revealed that each D. virilis gene is expressed in a unique pattern in the muscles of the thorax and abdomen. These muscle‐specific patterns of actin isoforms suggest a greater physiological diversity for the adult muscles of insects than has been appreciated to date from their categorization into fibrillar, tubular (non‐fibrillar) and supercontractile muscle types.
Cloning and expression analysis of a 5HT7‐like serotonin receptor cDNA from mosquito Aedes aegypti female excretory and respiratory systems
Authors: Pietrantonio P. V. , Jagge C. , McDowell C. 
Published: March 2003

AbstractIn the mosquito Aedes aegypti, 5‐HT changes the endogenous rhythm of contractions in the female hindgut and increases fluid secretion in the larval Malpighian tubule. The role of 5‐HT as a diuretic hormone in adults has been questioned. We cloned a cDNA encoding a serotonin receptor from a female A. aegypti Malpighian tubule library that is similar to the 5‐HT7 receptor from Drosophila melanogaster. The transcript was localized in the tracheolar cells associated with the female Malpighian tubules but no signal was detectable in the tubule epithelium. Immunohistochemistry with specific antibodies confirmed the receptor expression in tracheolar cells and hindgut, and western blots of these tissues showed the expected 50 kDa band. The results suggest a role for serotonin in respiration and that this receptor may coordinate the tubule‐hindgut response to serotonin during diuresis.
Fine scale mapping in the sex locus region of the honey bee (Apis mellifera)
Authors: Hasselmann M. , Fondrk M. K. , Page R. E. , Beye M. 
Published: March 2003

AbstractIsolating an unknown gene with fine‐scale mapping is possible in a ‘non‐model’ organism. Sex determination in honey bees consists of a single locus (sex locus) with several complementary alleles. Diploid females are heterozygous at the sex locus, whereas haploid males arise from unfertilized eggs and are hemizygous. The construction of specific inbred crosses facilitates fine scale mapping in the sex locus region of the honey bee. The high recombination rate in the honey bee reduces the physical distance between markers compared with model organisms and facilitates a novel gene isolation strategy based on step‐wise creation of new markers within small physical distances. We show that distances less than 25 kb can be efficiently mapped with a mapping population of only 1000 individuals. The procedure described here will accelerate the mapping, analysis and isolation of honey bee genes.
Genetic diversity and evolutionary relationships of the troglodytic ‘living fossil’Congeria kusceri (Bivalvia: Dreissenidae)
Authors: Stepien C. A. , Morton B. , Dabrowska K. A. , Guarnera R. A. , Radja T. , Radja B. 
Published: March 2003

AbstractPopulation genetic theory predicts that long‐term isolation of ‘living fossils’ in relic habitats might reduce genetic variability due to small population sizes and inbreeding. The recent description of a troglodytic ‘living fossil’Congeria kusceri — the only known subterranean bivalve mollusc — from a genus thought to be extinct since the Miocene, offers a unique opportunity to examine this hypothesis. Here, we use DNA sequences from two mitochondrial genes to compare levels of genetic variability and to test phylogenetic relationships of C. kusceri with surface‐dwelling dreissenid relatives. Phylogenetic analyses of sequences from the cytochrome oxidase 1 (COI) and 16S rDNA genes reveal that Mytilopsis is the sister genus to Congeria and this clade forms the sister taxon to Dreissena. Relatively high levels of DNA diversity characterized the population of C. kusceri (haplotypic diversity = 0.50 for 16S rDNA and 0.66 in the COI gene), in contrast to no intraspecific variability in populations of Dreissenapolymorpha, D. bugensis, Mytilopsisleucophaeta, and Corbiculafluminea. Maintenance of genetic variability in C. kusceri may result from long‐term population size stability, which merits further investigation. This underground species apparently was buffered from the climatic changes and resultant population bottlenecks that affected its surface‐dwelling relatives during the Pliocene and Pleistocene Ice Ages.
Molecular studies on the colonization of the Madeiran archipelago by house mice
Authors: GÜndüz İ. , Auffray J.‐C. , Britton‐Davidian J. , Catalan J. , Ganem G. , Ramalhinho M. G. , Mathias M. L. , Searle J. B. 
Published: March 2003

AbstractTo study the colonization history of the house mouse (Mus musculus domesticus) on the Madeiran archipelago, complete mitochondrial D‐loop sequences were obtained for 44 individuals from Madeira, Porto Santo and Ilhas Desertas. Altogether, 19 D‐loop haplotypes were identified which formed part of a single clade in a phylogeny incorporating haplotypes from elsewhere in the range of M. m. domesticus, indicating that the Madeiras were colonized from a single source. Similarities between the sequences found in the Madeiras and those in Scandinavia and northern Germany suggest that northern Europe was the source area, and there is the intriguing possibility that the Vikings may have accidentally brought house mice to the archipelago. However, there is no record of Vikings visiting the Madeiras; on historical grounds, Portugal is the most likely source area for Madeiran mice and further molecular data from Portugal are needed to rule out that possibility.
Phylogenetics, genome diversity and origin of modern leopard,Panthera pardus
Authors: Uphyrkina Olga , Johnson Warren E. , Quigley Howard , Miquelle Dale , Marker Laurie , Bush Mitchel , O'Brien Stephen J. 
Published: March 2003

AbstractLeopards,Panthera pardus, are widely distributed across southern Asia and sub‐Saharan Africa. The extent and phylogeographic patterns of molecular genetic diversity were addressed in a survey of 77 leopards from known geographical locales representing 13 of the 27 classical trinomial subspecies. Phylogenetic analysis of mitochondrial DNA sequences (727 bp ofNADH5and control region) and 25 polymorphic microsatellite loci revealed abundant diversity that could be partitioned into a minimum of nine discrete populations, tentatively named here as revised subspecies:P. parduspardus,P. p. nimr,P. p. saxicolor,P. p. fusca,P. p. kotiya,P. p. delacouri,P. p. japonensis,P. p. orientalisandP. p. melas. However, because of limited sampling of African populations, this may be an underestimate of modern phylogeographic population structure. Combined phylogeographic and population diversity estimates support an origin for modern leopard lineages 470 000–825 000 years ago in Africa followed by their migration into and across Asia more recently (170 000–300 000 years ago). Recent demographic reductions likely have led to genetic impoverishment inP. p. orientalisand in the island subspeciesP. p. kotiya.
Genetic diversity and population history of two related seabird species based on mitochondrial DNA control region sequences
Authors: Moum T. , Árnason E. 
Published: March 2003

AbstractGeographical variation in two related seabird species, the razorbill (Alca torda) and common guillemot (Uria aalge), was investigated using sequence analysis of mitochondrial DNA (mtDNA) control regions. We determined the nucleotide sequence of the variable 5′ segment of the control region in razorbills and common guillemots from breeding colonies across the Atlantic Ocean. The ecology and life history characteristics of razorbill and common guillemot are in many respects similar. They are both considered highly philopatric and have largely overlapping distributions in temperate and subarctic regions of the North Atlantic, yet the species were found to differ widely in the extent and spatial distribution of mtDNA variation. Moreover, the differences in genetic differentiation and diversity were in the opposite direction to that expected from a consideration of traditional classifications and current population sizes. Indices of genetic diversity were highest in razorbill and varied among colonies, as did genotype frequencies, suggestive of restrictions to gene flow. The distribution of genetic variation suggests that razorbills originated from a refugial population in the south‐western Atlantic Ocean through sequential founder events and subsequent expansion in the east and north. In common guillemots, genetic diversity was low and there was a lack of geographical structure, consistent with a recent population bottleneck, expansion and gene flow. We suggest that the reduced level of genetic diversity and differentiation in the common guillemot is caused by an inherent propensity for repeated population bottlenecks and concomitantly unstable population structure related to their specialized feeding ecology.
Data from amplified fragment length polymorphism (AFLP) markers show indication of size homoplasy and of a relationship between degree of homoplasy and fragment size
Authors: Vekemans X. , Beauwens T. , Lemaire M. , Roldán‐Ruiz I. 
Published: March 2003

AbstractWe investigate the distribution of sizes of fragments obtained from the amplified fragment length polymorphism (AFLP) marker technique. We find that empirical distributions obtained in two plant species, Phaseolus lunatus and Lolium perenne, are consistent with the expected distributions obtained from analytical theory and from numerical simulations. Our results indicate that the size distribution is strongly asymmetrical, with a much higher proportion of small than large fragments, that it is not influenced by the number of selective nucleotides nor by genome size but that it may vary with genome‐wide GC‐content, with a higher proportion of small fragments in cases of lower GC‐content when considering the standard AFLP protocol with the enzyme MseI. Results from population samples of the two plant species show that there is a negative relationship between AFLP fragment size and fragment population frequency. Monte Carlo simulations reveal that size homoplasy, arising from pulling together nonhomologous fragments of the same size, generates patterns similar to those observed in P. lunatus and L. perenne because of the asymmetry of the size distribution. We discuss the implications of these results in the context of estimating genetic diversity with AFLP markers.