Double aortic arch: implications of antenatal diagnosis, differential growth of arches during pregnancy, associated abnormalities and postnatal outcome.

OBJECTIVES: To evaluate the prenatal characteristics of double aortic arch (DAA), assess the relative size of the arches and their growth during pregnancy, describe associated cardiac, extracardiac and chromosomal/genetic abnormalities and review postnatal presentation and clinical outcome. METHODS: This was a retrospective cohort study of all fetuses with a confirmed diagnosis of DAA seen in five specialized referral centers in London, UK, between October 2012 and November 2019. Cases were identified from the hospitals' fetal databases. Fetal echocardiographic findings, intracardiac and extracardiac abnormalities, genetic defects, computed tomography (CT) findings and postnatal clinical presentation and outcome were evaluated. RESULTS: A total of 79 fetuses with DAA were included. Of those assessed postnatally, 48.6% had an atretic left aortic arch (LAA), while 5.1% had an atretic LAA at the first fetal scan and were misdiagnosed antenatally with right aortic arch (RAA). The LAA was atretic in 55.8% of those who underwent CT. DAA was an isolated abnormality in 91.1% of cases; 8.9% of patients had an additional intracardiac abnormality and 2.5% had both intra- and extracardiac abnormalities. Among the 52 cases that underwent genetic testing, 11.5% had genetic abnormalities and, specifically, the 22q11 microdeletion was identified in 3.8% of patients. At a median follow-up of 993.5 days, 42.5% of patients had developed symptoms of tracheoesophageal compression (5.5% during the first month after birth) and 56.2% had undergone intervention. Statistical analysis using the χ-square test showed no significant relationship between morphology of DAA (patency of both aortic arches vs atretic LAA) and the need for intervention (P = 0.134), development of vascular ring symptoms (P = 0.350) or evidence of airway compression on CT (P = 0.193). CONCLUSIONS: Most cases of DAA can be diagnosed easily at midgestation, as typically both arches are patent with a dominant RAA at this stage. However, we found that the LAA had become atretic in approximately half of the cases postnatally, supporting the theory of differential growth of the arches during pregnancy. DAA is usually an isolated abnormality; however, thorough assessment is required to exclude associated intra- and extracardiac anomalies and to determine the need for invasive prenatal genetic testing. Postnatally, early clinical assessment is needed and CT scan should be considered, irrespective of the presence of symptoms. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A novel simulation and analysis algorithm for high resolution optical transition radiation imaging.

The use of optical transition radiation (OTR) for charged particle beam imaging is a well-established and commonly used technique. As such, simulations of the images expected from an arbitrary transverse beam profile are important in both the design of such OTR imaging systems and the analysis of the data. However OTR image simulations of high-energy, low-emittance particle beams, that are becoming commonplace within accelerator physics, can be extremely challenging to produce and limited in their account of practical factors. In this paper we systematically show how high-energy OTR image simulations can be carried out using low-energy parameters, whilst providing little deviation in the resulting transverse beam profiles. Simulations require significantly less resources and can be combined with further analysis techniques, which would otherwise be too costly to be practically viable. Using this methodology as a basis for OTR simulations, we present a new method of analyzing OTR transverse beam profile data for high-energy, low-emittance beams. In contrast to previous work, this algorithm includes the effects of a finite bandwidth and directly allows the inclusion of optical effects, such as chromatic aberration.

Sarcoptic mange in wombats-A review and future research directions.

Sarcoptic mange is caused by the mite Sarcoptes scabiei and has recently been recognized as an emerging infectious disease of wildlife worldwide. The mite is one of the main causes of population decline in southern hairy-nosed (Lasiorhinus latifrons) and bare-nosed wombats (Vombatus ursinus). This review focuses on Sarcoptes scabiei infestations in wombats and provides insights into why the disease may be so prevalent in wombats. Current treatment practices and trials conducted in the field to reduce the incidence of sarcoptic mange in wombats are described and critically reviewed. Current and potential future avenues of research are discussed.

Effects of summer ozone on membrane lipid composition during subsequent frost hardening in Norway spruce [Picea abies (L.) Karst].

Norway spruce trees [Picea abies (L.) Karst] were exposed to ozone during the summers of three consecutive years and the fatty acid composition of the chloroplast membrane lipid, monogalactosyl diglyceride (MCDG) was analysed over the last 14 months. Significant variations in the degree of unsaturation and the percentage of linolenic acid (18:3) were not found, either on a seasonal basis or in relation to ozone treatment. The proportion of octadecatetraenoic acid (18:4) and other Δ5 fatty acids increased during autumn in trees grown in filtered air, but this seasonal effect was less pronounced in ozone-treated trees. The ratio of two forms of linoleate, Δ5,9 18:2 and Δ9,12 18:2 also increased significantly during the frost hardening period but not in trees previously exposed to ozone. This implies that two separate biosynthetic pathways exist, one for the Δ12 and one for the Δ12 desaturated series, which operate at different relative rates, depending on environmental conditions. It is suggested that ozone may interfere with the biosynthesis of 18:4 during frost hardening by inhibiting the Δ5 desaturation of oleate.

Nitrogen, phosphorus and potassium uptake and demand in Agrostis capillaris: the influence of elevated CO2 and nutrient supply.

Responses to elevated CO2 have been studied using Agrostis capillaris L., an upland grass which is abundant on nutrient-poor soils. Plants were grown in sand culture with a wide range of nitrogen, phosphorus and potassium concentrations, and the impact of CO2 on the demand for nutrients was determined using isotopic root bioassays. Plants grown with the smallest concentrations of N and P showed typical foliar symptoms associated with deficiency of these elements. However, even when supplies of N and P were limiting to growth, additional CO2 (250 ppm above ambient) influenced neither total N nor total P in above-ground tissues, nor nutrient demands as indicated by the bioassay. The estimates of the demand of the plants for K from the 86 Rb bioassay indicated an appreciable increase when plants were raised in elevated CO2 . For plants of the same size with the same nutrient supply, those grown in elevated CO2 consistently displayed an increased internal demand for K. Uptake of K was not however, enhanced by elevated CO2 even in non-limiting conditions and it might therefore be limited by a factor other than K supply. The overall conclusion from the experiments is that when A. capillaris is grown in elevated CO2 , uptake of N, P and K fails to increase proportionally with dry mass. This was true even when nutrient supplies were adequate, and it appears that nutrient-use-efficiency might increase to enable the plants to maintain growth in elevated CO2 .

Root production and turnover and carbon budgets of two contrasting grasslands under ambient and elevated atmospheric carbon dioxide concentrations.

Monoliths of two contrasting vegetation types, a species-rich grassland on a brown earth soil over limestone and species-poor community on a peaty gley, were transferred to solardomes and grown under ambient (350 µ 1-1 ) and elevated (600 µ11-1 ) CO2 for 2 yr. Shoot biomass was unaltered but root biomass increased by 40-50% under elevated CO2 . Root production was increased by elevated CO2 in the peat soil, measured both as instantaneous and cumulative rates, but only the latter measure was increased in the limestone soil. Root growth was stimulated more at 6 cm depth than at 10 cm in the limestone soil. Turnover was faster under elevated CO2 in the peat soil, but there was only a small effect on turnover in the limestone soil. Elevated CO2 reduced nitrogen concentration in roots and might have increased mycorrhizal colonization. Respiration rate was correlated with N concentration, and was therefore lower in roots grown at elevated CO2 . Estimates of the C budget of the two communities, based upon root production and on net C uptake, suggest that C sequestration in the peat soil increases by c. 0.2 kg C m -2 yr-1 (= 2 t ha yr-1 ) under elevated CO2 .

Regional variation in surface properties of Norway spruce and scots pine needles in relation to forest decline.

Measurements of leaf wettability (contact angle), amounts of epicuticular wax and of surface dust are reported for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L) Karst) trees growing at 12 sites in Europe from SW Germany to NE Scotland. At each site, three year classes (current year, 1 and 2-year-old) of needles were sampled from the mid-crown of up to 12 trees. Trees were selected at random from two strata, those showing visible decline symptoms (i.e. loss of needles or discoloration) and those apparently healthy. Needles for analysis were taken from apparently healthy (green) shoots in both cases. There were no significant differences between 'declining' and 'healthy' trees within sites, suggesting that leaf surface properties reflect environmental exposure rather than plant response. There were significant differences between sites, particularly for Norway spruce, which may be related to environmental factors including air pollution. Contact angles were consistently smaller at low-altitude sites in Britain and The Netherlands than at high-altitude sites in Germany where forests show decline symptoms. Leaf wettability decreased (contact angles increased) with wax amount and increased with dust amount. Leaf surface properties integrate environmental influences over long periods, and may be useful in identifying sites 'at risk' of developing decline symptoms, but causal relationships cannot be deduced without further direct experimentation.

Increased periconceptual maternal glycated haemoglobin in diabetic mothers reduces fetal long axis cardiac function.

OBJECTIVE: To compare ventricular long axis function in fetuses of diabetic mothers (FDM) with contemporaneously studied normal controls (N) and to assess the effect of pre-pregnancy diabetic control on these measurements. DESIGN: Long axis function was compared in 41 FDM and 159 N fetuses in a cross sectional observational study. SETTING: Fetal medicine unit. METHODS AND RESULTS: Echocardiography confirmed structural normality. Pulsed wave valvar Doppler velocimetry, lengthening and shortening myocardial velocities, and amplitude of ventricular long axis movement were recorded at the base of the left and right ventricular free walls and septum. Periconceptual diabetic control was assessed by haemoglobin A1c (HbA1c) in early pregnancy. Doppler and myocardial velocities were negatively related and myocardial thickness was positively related with HbA1c. In both cohorts all variables except mitral and tricuspid late filling (A wave) velocities were dependent on gestational age. FDM gestational age related values were higher for most variables and robust analysis of covariance showed significantly different maturation patterns in mitral valve E:A ratio (p = 0.036) and pulmonary velocity (p = 0.04), late lengthening myocardial velocities (left p = 0.016 and right p = 0.066), left myocardial shortening velocities (p = 0.008), and left free wall (p = 0.03) and septal (p = 0.04) amplitude of motion. FDM septal thickness was significantly increased throughout gestation (p < 0.0001). CONCLUSION: Periconceptual diabetic control influences fetal cardiac performance and myocardial hypertrophy but, unlike the pathophysiology of adult ventricular hypertrophy, is accompanied by functional adaptation. It is unlikely to explain the increased rate of late stillbirth observed in diabetic pregnancies.

Can atrioventricular septal defects exist with intact septal structures?

The hallmark of an atrioventricular septal defect (AVSD) is a common atrioventricular junction, giving rise to a trileaflet left atrioventricular valve. AVSDs have the potential for interatrial shunting alone, interventricular shunting alone, or both. AVSDs without interatrial or interventricular communications have been identified at postmortem examination, but there are no reports of AVSDs with intact septal structures diagnosed in life. Six patients are described with AVSD and intact atrial and ventricular septa diagnosed echocardiographically. This report shows that AVSDs can exist without interatrial or interventricular communications and that the characteristic feature of this condition, the common atrioventricular junction with a trileaflet left atrioventricular valve, can be diagnosed in life by using cross sectional echocardiography. AVSDs with intact septal structures may be more common than previously described.

Effects of elevated CO2 and nutrient supply on the seasonal growth and morphology of Agrostis capillaris.

Responses to elevated CO2 have been studied using an upland grass species, Agrostis capillaris L. The plants were grown in sand culture with a range of N, P and K concentrations, in 'Solardome' growth chambers with either ambient air or a CO2 concentration of 250µmol CO2 mol(-1) above ambient The interactive effects of high CO2 and nutrient supply (in plant growth and morphology were monitored throughout the growing season. A. capillaris exhibited positive growth responses to enhanced CO2 even at limiting supplies of N and P. Moreover, greater shoot mass at elevated CO2 was attributed to disproportionate increases in leaf and tiller number, resulting in an increase in the average leaf number per tiller. However, total leaf area remained unaffected, indicating that leaf size was reduced. There was no evidence of any acclimation in the growth response of A. capillaris to additional CO2 , even in N and P-stressed plants. On the contrary, a stimulation in leaf production was observed later in the growing season. A consistent interaction was observed between N and P concentrations, whereby the response to one element was greater at higher concentrations of the other. In addition, there were indications of competition among the three elements for uptake at the root. These findings indicate the importance of multifactorial nutrient experiments in developing an understanding of the complex relationships during CO2 enrichment.

Studies of fatty liver and kidney syndrome in chickens: dynamics of glucose metabolism.

1. Fatty liver and kidney syndrome (FLKS) was induced in a proportion of a group of 4-week-old chickens by giving a diet of meat meal and wheat; inclusion in the diet of animal tallow for 54 h substantially reduced the occurrence of FLKS. 2. Measurements of dynamic aspects of glucose metabolism were made with single injections of [2-3H]glucose which indicated that birds given the 'FLKS-inducing' diet and showing physical symptoms of FLKS had significantly lower rates of synthesis of glucose than birds given either the same diet supplemented with tallow or a commercial diet. 3. In a second series of experiments glucose metabolism was studied in birds (1) with or without physical symptoms that were given the 'FLKS-inducing' diet and (2) birds given the same diet supplemented with tallow or biotin. Affected birds fed the 'FLKS-inducing' diet had significantly lower plasma glucose concentrations, pool sizes and synthesis rates than birds fed the same diet and not showing symptoms, or birds fed the supplemented diets. 4. It is suggested that the cause of death in birds with FLKS is a low rate of gluconeogenesis during periods without feed which results in a lack of glucose to meet essential functions.

The effect of ovariectomy on liver metabolism and maintenance energy requirement of hens.

Six pullets from each of an egg-producing and meat-producing strain were ovariectomised at 12 weeks of age. Ovarian regrowth occurred in two of the egg-producing and four of the meat-producing strain. 2. Measurements of heat production and energy balance were made after peak lay with ovariectomised and sham-operated laying pullets of both strains. Measurements on the ovariectomised pullets were made before and after implantation with oestrogen pellets. 3. Within each strain the ME requirements for maintenance (per kg W0.75), determined by linear regression analysis, were similar whether or not the starvation heat production data were included. 4. The ME requirements for maintenance decreased substantially after ovariectomy but subsequent implantation with oestrogen pellets did not increase these requirements. 5. Studies of hepatic enzyme activities indicated that the major influence of the mature ovary was on hepatic lipid metabolism. This was exerted through a specific stimulation of lipogenesis rather than a general increase in metabolism.

Influence of twin-twin transfusion syndrome on fetal cardiovascular structure and function: prospective case-control study of 136 monochorionic twin pregnancies.

OBJECTIVE: To test the hypothesis that identical twins show no inter-twin differences in cardiovascular structure or physiology in fetal life unless there has been twin-twin transfusion syndrome. DESIGN: Unselected prospective case-control observational study of fetoplacental haemodynamics including echocardiography at a median of 24 (16.7 to 32.3) weeks, with postnatal confirmation of congenital heart disease or normality. SETTING: Fetal medicine unit. PATIENTS: 136 women with monochorionic diamniotic twin pregnancies, of which 47 fetal twin pairs (35%) had twin-twin transfusion syndrome. RESULTS: There were no haemodynamic differences between the bigger fetus (twin 1) and the smaller co-twin (twin 2) in uncomplicated monochorionic diamniotic pairs. In twin-twin transfusion syndrome, recipient fetuses had increased aortic and pulmonary velocities compared with their donor co-twins (mean (SD): 0.73 (0.23) m/s and 0.63 (0.14) m/s), respectively, v 0.53 (0.16) m/s and 0.48 (0.10) m/s in donor twins; p = 0.003 (aortic) and < 0.0001 (pulmonary)), and also in comparison with twin 1 and twin 2. The overall prevalence of congenital heart disease was increased above that in singletons (3.8% v 0.56%; 6.9% in twin-twin transfusion v 2.3% in uncomplicated monochorionic diamniotic twins), with inter-twin discordance for defects. The prevalence in recipient twins was 11.9% (p = 0.014 v uncomplicated control twins). CONCLUSIONS: Fetuses with an identical genome but no circulatory imbalance have similar cardiovascular physiology but discordant phenotypic expression of congenital heart disease. The high prevalence of congenital heart disease in monochorionic diamniotic twins merits detailed fetal echocardiography.