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Gut microbiota data obtained by DNA sequencing are not only complex because of the number of taxa that may be detected within human cohorts, but also compositional because characteristics of the microbiota are described in relative terms (e.g., “relative abundance” of particular bacterial taxa expressed as a proportion of the total abundance of taxa). Nutrition researchers often use standard principal component analysis (PCA) to derive dietary patterns from complex food data, enabling each participant's diet to be described in terms of the extent to which it fits their cohort's dietary patterns. However, compositional PCA methods are not commonly used to describe patterns of microbiota in the way that dietary patterns are used to describe diets. This approach would be useful for identifying microbiota patterns that are associated with diet and body composition. The aim of this study is to use compositional PCA to describe gut microbiota profiles in 5 year old children and explore associations between microbiota profiles, diet, body mass index (BMI) z-score, and fat mass index (FMI) z-score. This study uses a cross-sectional data for 319 children who provided a faecal sample at 5 year of age. Their primary caregiver completed a 123-item quantitative food frequency questionnaire validated for foods of relevance to the gut microbiota. Body composition was determined using dual-energy x-ray absorptiometry, and BMI and FMI z-scores calculated. Compositional PCA identified and described gut microbiota profiles at the genus level, and profiles were examined in relation to diet and body size. Three gut microbiota profiles were found. Profile 1 (positive loadings on Blautia and Bifidobacterium; negative loadings on Bacteroides) was not related to diet or body size. Profile 2 (positive loadings on Bacteroides; negative loadings on uncultured Christensenellaceae and Ruminococcaceae) was associated with a lower BMI z-score (r = -0.16, P = 0.003). Profile 3 (positive loadings on Faecalibacterium, Eubacterium and Roseburia) was associated with higher intakes of fibre (r = 0.15, P = 0.007); total (r = 0.15, P = 0.009), and insoluble (r = 0.13, P = 0.021) non-starch polysaccharides; protein (r = 0.12, P = 0.036); meat (r = 0.15, P = 0.010); and nuts, seeds and legumes (r = 0.11, P = 0.047). Further regression analyses found that profile 2 and profile 3 were independently associated with BMI z-score and diet respectively. We encourage fellow researchers to use compositional PCA as a method for identifying further links between the gut, diet and obesity, and for developing the next generation of research in which the impact on body composition of dietary interventions that modify the gut microbiota is determined.
One of the best known (and best preserved) of late-antique ivories is what is generally known as the Stilicho diptych, kept in the tesoro of the cathedral at Monza. It represents a military man with a spear and shield on one panel, and, on the other, a high-ranking woman holding a flower above the head of a small boy, not more than 10 years old; he stands between them wearing a chlamys and holding the codicils of office in his left hand (fig. 1). Ever since the basic article by C. Jullian more than 130 years ago, it has been generally accepted that the only candidates who fit this description are the western magister utriusque militiae Stilicho (d. 408), his wife Serena, the niece and (according to Claudian) adoptive daughter of Theodosius I, and their son Eucherius, appointed to the office of tribunus et notarius in (probably) 395/6.
A once popular game enjoying something of a revival of late is identifying covert anti-Christian polemic in pagan texts of late antiquity. The polemic is always covert because it is assumed that pagans were afraid to express pagan views openly. But this is pure assumption, for which no real evidence has ever been produced. Of course, direct attack or scurrilous abuse would have been imprudent, but up to the Theodosian age at any rate courteous debate and disagreement were certainly tolerated (for example, Volusianus's letter to Augustine questioning the virgin birth). A recent book by Stéphane Ratti is the first systematic attempt to document this supposed pagan fear, going so far as to maintain that already by the late fourth century pagans were afraid to reveal their paganism in their private letters. Because so many private letters survive from the fourth and fifth centuries, both pagan and Christian, this is a hypothesis that can be tested.
The letters of Q. Aurelius Symmachus cos. 391 might seem a promising target. A well-known pagan himself, Symmachus corresponded with Vettius Agorius Praetextatus and both the Nicomachi Flaviani, the most notorious pagans of the age. His more than 900 letters might be expected to contain a trove of information about the last days of Roman paganism. Yet if the 390s saw a pagan revival, Symmachus's letters reveal little hint of it.
Scholars used to assume that this is because they were edited after his death by his son Memmius Symmachus, to protect both himself and his father's reputation. Ratti has argued that the explanation for their lack of pagan content is self-censorship by Symmachus himself, afraid to speak his mind. Both explanations might seem reasonable but find little support in the letters themselves. The question has in fact been surprisingly little studied. What follows is an attempt to dig somewhat deeper than has been done hitherto.
It is true that, if Symmachus wrote to (or about) the supposedly pro-pagan Eugenius or Arbogast during the period of their rebellion against Theodosius, no such letters were included. But even if they had been pro-pagan, that would have been irrelevant to Symmachus's paganism. Anyone, pagan or Christian, who had written to (or about) a usurper would take care to destroy all such correspondence on the usurper's fall. There are no letters to the Christian usurper Magnus Maximus either.
This paper takes as its point of departure two much discussed fifth-century artifacts, an uninscribed and undated consular diptych in Halberstadt (Fig. 9), and the inscribed and (on the face of it) exactly dated consular missorium of Ardabur Aspar in Florence (Fig. 15), both hitherto presumed issued by western consuls and manufactured in western workshops. After calling into question the established criteria for distinguishing western from eastern diptychs, I propose a new set of criteria and a new date and interpretation of both objects, mainly in the light of a more comprehensive examination of the iconography of city personifications, in literature as well as art.
The IAU Working Group on Extrasolar Planets (WGESP) was created by the Executive Council as a Working Group of Division III. This decision took place in June 1999, that is only 7 years after the discovery of planets around the pulsar PSR B1257+12 and 4 years after the discovery of 51 Peg b. This working group was renewed for 3 years at the General Assembly in 2003 in Sydney, Australia. It was chaired by Alan Boss from Carnegie Institution of Washington. The WGESP members were Paul Butler, William Hubbard, Philip Ianna, Martin Kürster, Jack Lissauer, Michel Mayor, Karen Meech, Francois Mignard, Alan Penny, Andreas Quirrenbach, Jill Tarter, and Alfred Vidal-Madjar.
Members of the late Roman élite commemorated the holding of certain offices by the distribution of ivory diptychs. This paper attempts to show how diptychs came to play this rôle; that they were not originally distributed by consuls but by any official who provided games; that they had nothing to do with the ecclesiastical diptychs that are first heard of at about the same time; that the custom spread from east to west, not from west to east; and that the earliest western consular diptychs are not illustrated with scenes from games because there were no multi-day consular games at Rome before the fifth century.
Red cell alloimmunization, with its resultant fetal anemia, continues to be a cause of perinatal morbidity and mortality. Recent decades have seen major advances in the understanding and management of the condition and it is the aim of this chapter to review this. In particular, the role of direct fetal therapy for fetal anemia will be described, which has been one of the success stories of fetal medicine.
Red cell alloimmunization in pregnancy
There is a risk of red cell alloimmunization in any pregnancy where the mother is exposed to fetal red cells that possess antigens for which her own red cells are negative. The underlying mechanism for this exposure during pregnancy is fetomaternal hemorrhage (FMH). As a result, the mother mounts an immune response that is initially composed of IgM antibodies – large molecules that do not cross the placenta. Later, IgG antibodies are produced that are able to cross the placenta. This represents the primary immune response. A second exposure to the foreign antigens, for example in the next pregnancy, results in the secondary immune response and a rapid production of IgG antibodies which cross the placenta and cause fetal red cell hemolysis. The risk and severity of alloimmunization increases with each subsequent pregnancy that is positive for the relevant red cell antigen.
This paper discusses the widely held view that politics in fifth- and sixth-century Italy were largely driven by rivalry between the two great families of the Anicii and the Decii, supposedly following distinctive policies (pro- or anti-eastern, philo- or anti-barbarian, etc.). It is probable that individual members of these (and other) families had feuds and disagreements from time to time, but there is absolutely no evidence for continuing rivalry between Decii and Anicii as families, let alone on specific issues of public policy. Indeed by the mid-fifth century the Anicii fell into a rapid decline. The nobility continued to play a central rôle in the social and (especially) religious life of late fifth- and early sixth-century Italy. Their wealth gave them great power, but it was power that they exercised in relatively restricted, essentially traditional fields, mainly on their estates and in the city of Rome. The quite extraordinary sums they spent on games right down into the sixth century illustrate their overriding concern for popular favour at a purely local level. In this context there was continuing competition between all noble families rich enough to compete. Indeed, the barbarian kings encouraged the nobility to spend their fortunes competing with each other to the benefit of the city and population of Rome.
Commission 53 was created at the 2006 Prague General Assembly (GA) of the IAU, in recognition of the outburst of astronomical progress in the field of extrasolar planet discovery, characterization, and theoretical work that has occurred since the discovery of the first planet in orbit around a solar-type star in 1995. Commission 53 is the logical successor to the IAU Working Group on Extrasolar Planets (WGESP), which ended its six years of existence in August 2006. The founding President of Commission 53 was Michael Mayor, in honor of his seminal contributions to this new field of astronomy. The current President is Alan Boss, the former chair of the WGESP. The current members of the Commission 53 (C53) Organizing Committee (OC) began their service in August 2009 at the conclusion of the Rio de Janeiro IAU GA.
Twin pregnancies are associated with significantly increased rates of fetal loss, neonatal loss and neonatal morbidity than singleton pregnancies. Perinatal mortality data collated for the United Kingdom demonstrate a stillbirth rate approximately 2.5–3.0 times that seen in singleton pregnancies and a neonatal loss rate of approximately seven times that seen in singleton pregnancies. The adverse outcome of twin pregnancy reflects an increased risk of virtually all obstetric complications, particularly preterm delivery and fetal growth restriction, in addition to specific complications of monochorionic twins.
Classification of twin pregnancy
Twins can be classified by their zygosity (number of fertilised ova – nonidentical dizygotic twins or identical monozygotic twins) or by their chorionicity (the number of placentae – dichorionic or monochorionic/one shared placenta). The latter classification is of clinical relevance for three important reasons: (1) it can be determined antenatally, (2) it influences prenatal screening and the management of certain obstetric complications and (3) it predicts the risk of specific complications. Monochorionic twins have a six-fold risk of loss before 24 weeks of gestation and two to three-fold increased risk of stillbirth and early neonatal deaths when compared with dichorionic twins.
EMBRYOLOGY OF MONOCHORIONIC TWIN PREGNANCY
Approximately 30% of twins are identical or monozygotic, of which 70% are monochorionic (Figure 9.1). This occurs when a single fertilised ovum splits into identical twins 3 days after fertilisation. At this point in time, the outer chorion has started to differentiate and so, although embryo division occurs, the resultant fetuses will share an outer chorion (placenta and chorionic membrane).
Antenatal screening identifies those pregnancies at ‘high risk’ of fetal complications, such as aneuploidy, intrauterine infection and fetal anaemia, but the diagnosis can only be confirmed or refuted by direct examination of fetal tissue or blood. Until recently, fetal cells could only be obtained by an invasive procedure: amniocentesis, chorionic villus sampling (CVS) or cordocentesis. While fetal cells can now be extracted from the maternal circulation and analysed for specific indications, this technique is not widely available and it clinical use remains limited. Invasive testing therefore remains the cornerstone of prenatal diagnosis.
This chapter will focus on the prenatal diagnostic techniques used to determine fetal karyotype. Readers are referred to Chapters 5 and 10 for information on the role of prenatal diagnostic tests in the management of fetal anaemia and intrauterine infection.
Who should be offered invasive prenatal testing?
All pregnant women should be made aware that both diagnostic and screening tests for aneuploidy are available in pregnancy. The majority of women will choose to have a screening test, as this carries no innate risk to the pregnancy, and will not wish to discuss diagnostic testing in any form. For others, the consequences of having a child affected by aneuploidy are of such enormity that no screening test will give sufficient reassurance. If such concerns are expressed, the mother must have ample opportunity to discuss the full range of diagnostic tests that are available. It is for the woman to decide which risk is most acceptable.