An Approach to the Aetiology of Prematurity: A Study of the Obstetric Histories of Mothers of Premature Babies with an Appendix on the Progress and Development of Premature Children

1. The neo-natal death rate among premature babies is very much higher than that among mature babies, and as a result of the changing pattern in infant mortality in recent years prematurity has become relatively more important as a cause, or contributing cause, of infant deaths. 2. When surviving premature children are compared with surviving mature children it has been found that the premature children are at a disadvantage in various respects. 3. For these reasons it is important to attempt to reduce the incidence of prematurity, but this object is hampered by inadequate knowledge of the aetiology of prematurity. 4. A premature child is defined as a child who weighs 5 1/2 lbs. (2500 G.) or less at birth, regardless of the length of gestation. In spite of its faults, this is the best definition available. 5. The aetiology of prematurity is not fully understood. In about half the cases of prematurity which occur no cause can be defined. In the remaining half the prematurity is associated with complications of pregnancy and it is generally assumed that these complications are the cause of the prematurity, but the way by which this is brought about is not known. It is known that a large number of factors such as social class, maternal age, and parity influence the prematurity rate. It is also known that prematurity tends to be repeated and this tendency may be associated with a tendency to abort and show signs of toxaemia. 6. The aim of this study was to examine the occurrence of prematurity against the background of the reproductive tendencies of the mothers of premature children. In order to do this, we interviewed the mothers of 515 single-born premature children who had been born in Glasgow during the year 1950, and obtained the obstetric histories of these mothers. There does not appear to be any bias in the sample which would influence the conclusions which will be drawn. 7. The incidence of prematurity among the single-born sib- lings of these premature children was 26.4%. It was shown that in a number of cases the prematurity in 1950 might have been caused by factors associated with that particular pregnancy, but if these cases were excluded it would be reasonable to postulate that the prematurity in the remaining cases was due to a predisposition on the part of the mothers to have premature babies. 8. This predisposition to prematurity is made up of two tendencies: one to have mature babies of low birth weight which are by definition premature, and the other to have abnormally short pregnancies. 9. There is no fundamental difference between the reproductive histories of mothers who have premature babies after uncomplicated pregnancies and mothers who have premature babies after complicated pregnancies. Such differences as appear to exist are due to a tendency for the mothers who had complicated pregnancies to have still-births and abortions instead of premature live-births among their other pregnancies, and to the fact that most of the mature children of low birth weight who are classified as premature are born after uncomplicated pregnancies. There is an important relationship between prematurity and complications of pregnancy in that prematurity occurs more often in the presence of complications than in their absence, but the similarity in reproductive histories, and the absence of satisfactory evidence to the contrary, justifies the rejection of the view that prematurity is caused by complications of pregnancy. 10. The incidence of abortions among the other pregnancies of the mothers of these premature children was unduly high, especially when the birth weight of the premature child had been low. This and other evidence led to the conclusion that there is some common factor in the aetiologies of abortion, prematurity, and toxaemia. 11. The main conclusion drawn from this study is that most cases of prematurity are due to a maternal predisposition to have premature babies. This may simply be a tendency for certain mothers, probably of small stature, to have full-time babies of low birth weight,but more often it is due to a tendency to have abnormally short pregnancies. These short pregnancies are caused by a maternal-foetal reaction due ultimately to the genetic constitution of the foetus. This conclusion is supported by the finding that there is a relationship between a history of prematurity in the family of either parent and the incidence of prematurity among their children. Most of the remaining cases of prematurity, which are not due to a maternal predisposition, are caused by the action of factors associated with first pregnancies, high parity, and pregnancies during the later child-bearing years. A small residue is due to various other causes

Assessment of acute headache in adults - what the general physician needs to know.

Headache is common. Up to 5% of attendances to emergency departments and acute medical units are due to headache. Headache is classified as either primary (eg migraine, cluster headache) or secondary to another cause (eg meningitis, subarachnoid haemorrhage). Even in the acute setting the majority of cases are due to primary causes. The role of the attending physician is to take a comprehensive history to diagnose and treat benign headache syndromes while ruling out sinister aetiologies. This brief article summarises the approach to assessment of headache presenting in acute and emergency care

Rising minimum daily flows in northern Eurasian rivers: A growing influence of groundwater in the high‐latitude hydrologic cycle

A first analysis of new daily discharge data for 111 northern rivers from 1936–1999 and 1958–1989 finds an overall pattern of increasing minimum daily flows (or “low flows”) throughout Russia. These increases are generally more abundant than are increases in mean flow and appear to drive much of the overall rise in mean flow observed here and in previous studies. Minimum flow decreases have also occurred but are less abundant. The minimum flow increases are found in summer as well as winter and in nonpermafrost as well as permafrost terrain. No robust spatial contrasts are found between the European Russia, Ob\u27, Yenisey, and Lena/eastern Siberia sectors. A subset of 12 unusually long discharge records from 1935–2002, concentrated in south central Russia, suggests that recent minimum flow increases since ∼1985 are largely unprecedented in the instrumental record, at least for this small group of stations. If minimum flows are presumed sensitive to groundwater and unsaturated zone inputs to river discharge, then the data suggest a broad‐scale mobilization of such water sources in the late 20th century. We speculate that reduced intensity of seasonal ground freezing, together with precipitation increases, might drive much of the well documented but poorly understood increases in river discharge to the Arctic Ocean

Cohort profile: the avon longitudinal study of parents and children: ALSPAC mothers cohort

The Avon Longitudinal Study of Children and Parents (ALSPAC) was established to understand how genetic and environmental characteristics influence health and development in parents and children. All pregnant women resident in a defined area in the South West of England, with an expected date of delivery between 1st April 1991 and 31st December 1992, were eligible and 13 761 women (contributing 13 867 pregnancies) were recruited. These women have been followed over the last 19–22 years and have completed up to 20 questionnaires, have had detailed data abstracted from their medical records and have information on any cancer diagnoses and deaths through record linkage. A follow-up assessment was completed 17–18 years postnatal at which anthropometry, blood pressure, fat, lean and bone mass and carotid intima media thickness were assessed, and a fasting blood sample taken. The second follow-up clinic, which additionally measures cognitive function, physical capability, physical activity (with accelerometer) and wrist bone architecture, is underway and two further assessments with similar measurements will take place over the next 5 years. There is a detailed biobank that includes DNA, with genome-wide data available on >10 000, stored serum and plasma taken repeatedly since pregnancy and other samples; a wide range of data on completed biospecimen assays are available. Details of how to access these data are provided in this cohort profile

Dissecting the Genetic Basis of Variation in Drosophila Sleep Using a Multiparental QTL Mapping Resource

There is considerable variation in sleep duration, timing and quality in human populations, and sleep dysregulation has been implicated as a risk factor for a range of health problems. Human sleep traits are known to be regulated by genetic factors, but also by an array of environmental and social factors. These uncontrolled, non-genetic effects complicate powerful identification of the loci contributing to sleep directly in humans. The model system, Drosophila melanogaster, exhibits a behavior that shows the hallmarks of mammalian sleep, and here we use a multitiered approach, encompassing high-resolution QTL mapping, expression QTL data, and functional validation with RNAi to investigate the genetic basis of sleep under highly controlled environmental conditions. We measured a battery of sleep phenotypes in >750 genotypes derived from a multiparental mapping panel and identified several, modest-effect QTL contributing to natural variation for sleep. Merging sleep QTL data with a large head transcriptome eQTL mapping dataset from the same population allowed us to refine the list of plausible candidate causative sleep loci. This set includes genes with previously characterized effects on sleep and circadian rhythms, in addition to novel candidates. Finally, we employed adult, nervous system-specific RNAi on the Dopa decarboxylase, dyschronic, and timeless genes, finding significant effects on sleep phenotypes for all three. The genes we resolve are strong candidates to harbor causative, regulatory variation contributing to sleep

Dissecting the Genetic Basis of Variation in Drosophila Sleep Using a Multiparental QTL Mapping Resource

This work is licensed under a Creative Commons Attribution 4.0 International License.There is considerable variation in sleep duration, timing and quality in human populations, and sleep dysregulation has been implicated as a risk factor for a range of health problems. Human sleep traits are known to be regulated by genetic factors, but also by an array of environmental and social factors. These uncontrolled, non-genetic effects complicate powerful identification of the loci contributing to sleep directly in humans. The model system, Drosophila melanogaster, exhibits a behavior that shows the hallmarks of mammalian sleep, and here we use a multitiered approach, encompassing high-resolution QTL mapping, expression QTL data, and functional validation with RNAi to investigate the genetic basis of sleep under highly controlled environmental conditions. We measured a battery of sleep phenotypes in >750 genotypes derived from a multiparental mapping panel and identified several, modest-effect QTL contributing to natural variation for sleep. Merging sleep QTL data with a large head transcriptome eQTL mapping dataset from the same population allowed us to refine the list of plausible candidate causative sleep loci. This set includes genes with previously characterized effects on sleep and circadian rhythms, in addition to novel candidates. Finally, we employed adult, nervous system-specific RNAi on the Dopa decarboxylase, dyschronic, and timeless genes, finding significant effects on sleep phenotypes for all three. The genes we resolve are strong candidates to harbor causative, regulatory variation contributing to sleep

Tuning the effects of Landau-level mixing on anisotropic transport in quantum Hall systems

Electron-electron interactions in half-filled high Landau levels in two-dimensional electron gases in a strong perpendicular magnetic field can lead to states with anisotropic longitudinal resistance. This longitudinal resitance is generally believed to arise from broken rotational invariance, which is indicated by charge density wave (CDW) order in Hartree-Fock calculations. We use the Hartree-Fock approximation to study the influence of externally tuned Landau level mixing on the formation of interaction induced states that break rotational invariance in two-dimensional electron and hole systems. We focus on the situation when there are two non-interacting states in the vicinity of the Fermi level and construct a Landau theory to study coupled charge density wave order that can occur as interactions are tuned and the filling or mixing are varied. We examine in detail a specific example where mixing is tuned externally through Rashba spin-orbit coupling. We calculate the phase diagram and find the possibility of ordering involving coupled striped or triangular charge density waves in the two levels. Our results may be relevant to recent transport experiments on quantum Hall nematics in which Landau-level mixing plays an important role.Comment: 25 pages, 6 figure

Numerical models of collisions between core-collapse supernovae and circumstellar shells

Recent observations of luminous Type IIn supernovae (SNe) provide compelling evidence that massive circumstellar shells surround their progenitors. In this paper we investigate how the properties of such shells influence the SN lightcurve by conducting numerical simulations of the interaction between an expanding SN and a circumstellar shell ejected a few years prior to core collapse. Our parameter study explores how the emergent luminosity depends on a range of circumstellar shell masses, velocities, geometries, and wind mass-loss rates, as well as variations in the SN mass and energy. We find that the shell mass is the most important parameter, in the sense that higher shell masses (or higher ratios of M_shell/M_SN) lead to higher peak luminosities and higher efficiencies in converting shock energy into visual light. Lower mass shells can also cause high peak luminosities if the shell is slow or if the SN ejecta are very fast, but only for a short time. Sustaining a high luminosity for durations of more than 100 days requires massive circumstellar shells of order 10 M_sun or more. This reaffirms previous comparisons between pre-SN shells and shells produced by giant eruptions of luminous blue variables (LBVs), although the physical mechanism responsible for these outbursts remains uncertain. The lightcurve shape and observed shell velocity can help diagnose the approximate size and density of the circumstellar shell, and it may be possible to distinguish between spherical and bipolar shells with multi-wavelength lightcurves. These models are merely illustrative. One can, of course, achieve even higher luminosities and longer duration light curves from interaction by increasing the explosion energy and shell mass beyond values adopted here.Comment: Accepted for publication in MNRAS. Tables of numerical results (SN lightcurves and velocities) to be published online. (Updated to fix figures