Adverse perinatal outcomes are strongly associated with degree of abnormality in uterine artery Doppler pulsatility index

OBJECTIVES

To investigate the association between varying degrees of abnormality in the uterine artery Doppler pulsatility index (UtA-PI) and adverse perinatal outcomes.

METHODS

Prospective study of 33,364 women who gave birth to singleton, non-anomalous babies in Oxford, following universal measurement of UtA-PI in mid-pregnancy. Relative risk ratios for the primary outcomes of extended perinatal mortality and live birth with severe small-for-gestational-age (SGA) were calculated by multinomial logistic regression, for early preterm birth (<34+0) and late preterm/term birth (≥34+0). The risks were also investigated for iatrogenic preterm birth or a composite adverse outcome before 34+0 weeks.

RESULTS

Compared with women with normal UtA-PI, the risk of extended perinatal mortality before 34+0 weeks was higher in women with UtA-PI >90th centile (RRR 4.7, 95% CI 2.7-8.0, p<0.001), but this was not demonstrated in later births. The risk of severe SGA birth was strongly associated with abnormal UtA-PI for both early births (RRR 26.0, 95% CI 11.6-58.2, p<0.001), and later births (RRR 2.3, 95% CI 1.8-2.9, p<0.001). Women with a raised UtA-PI were more likely to undergo early iatrogenic birth (RRR 7.8, 95% CI 5.5-11.2, p<0.001). For each of the outcomes and the composite outcome, the risk increased significantly in association with the degree of abnormality, through the 90th, 90-94th, 95-99th and >99th centiles (ptrend<0.001).

CONCLUSIONS

An elevated UtA-PI is a key predictor of iatrogenic preterm birth, severe SGA and perinatal loss up to 34+0 weeks. It is the 90th centile that should be used, and management should be further tailored to the degree of abnormality, as pregnancies with very raised UtA-PI measurements constitute a group at extreme risk. This article is protected by copyright. All rights reserved.

Unravelling the impact of fat content on the microbial dynamics and spatial distribution of foodborne bacteria in tri-phasic viscoelastic 3D models

The aim of the current study is to develop and characterise novel complex multi-phase in vitro 3D models, for advanced microbiological studies. More specifically, we enriched our previously developed bi-phasic polysaccharide (Xanthan Gum)/protein (Whey Protein) 3D model with a fat phase (Sunflower Oil) at various concentrations, i.e., 10%, 20%, 40% and 60% (v/v), for better mimicry of the structural and biochemical composition of real food products. Rheological, textural, and physicochemical analysis as well as advanced microscopy imaging (including spatial mapping of the fat droplet distribution) of the new tri-phasic 3D models revealed their similarity to industrial food products (especially cheese products). Furthermore, microbial growth experiments of foodborne bacteria, i.e., Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Lactococcus lactis on the surface of the 3D models revealed very interesting results, regarding the growth dynamics and distribution of cells at colony level. More specifically, the size of the colonies formed on the surface of the 3D models, increased substantially for increasing fat concentrations, especially in mid- and late-exponential growth phases. Furthermore, colonies formed in proximity to fat were substantially larger as compared to the ones that were located far from the fat phase of the models. In terms of growth location, the majority of colonies were located on the protein/polysaccharide phase of the 3D models. All those differences at microscopic level, that can directly affect the bacterial response to decontamination treatments, were not captured by the macroscopic kinetics (growth dynamics), which were unaffected from changes in fat concentration. Our findings demonstrate the importance of developing structurally and biochemically complex 3D in vitro models (for closer proximity to industrial products), as well as the necessity of conducting multi-level microbial analyses, to better understand and predict the bacterial behaviour in relation to their biochemical and structural environment. Such studies in advanced 3D environments can assist a better/more accurate design of industrial antimicrobial processes, ultimately, improving food safety.

On the evaluation of the antimicrobial effect of grape seed extract and cold atmospheric plasma on the dynamics of Listeria monocytogenes in novel multiphase 3D viscoelastic models

The demand for products that are minimally processed and produced in a sustainable way, without the use of chemical preservatives or antibiotics have increased over the last years. Novel non-thermal technologies such as cold atmospheric plasma (CAP) and natural antimicrobials such as grape seed extract (GSE) are attractive alternatives to conventional food decontamination methods as they can meet the above demands. The aim of this study was to investigate the microbial inactivation potential of GSE, CAP (in this case, a remote air plasma with an ozone-dominated RONS output) and their combination against L. monocytogenes on five different 3D in vitro models of varying rheological, structural, and biochemical composition. More specifically, we studied the microbial dynamics, as affected by 1 % (w/v) GSE, CAP or their combination, in three monophasic Xanthan Gum (XG) based 3D models of relatively low viscosity (1.5 %, 2.5 % and 5 % w/v XG) and in a biphasic XG/Whey Protein (WPI) and a triphasic XG/WPI/fat model. A significant microbial inactivation (comparable to liquid broth) was achieved in presence of GSE on the surface of all monophasic models regardless of their viscosity. In contrast, the GSE antimicrobial effect was diminished in the multiphasic systems, resulting to only a slight disturbance of the microbial growth. In contrast, CAP showed better antimicrobial potential on the surface of the complex multiphasic models as compared to the monophasic models. When combined, in a hurdle approach, GSE/CAP showed promising microbial inactivation potential in all our 3D models, but less microbial inactivation in the structurally and biochemically complex multiphasic models, with respect to the monophasic models. The level of inactivation also depended on the duration of the exposure to GSE. Our results contribute towards understanding the antimicrobial efficacy of GSE, CAP and their combination as affected by robustly controlled changes of rheological and structural properties and of the biochemical composition of the environment in which bacteria grow. Therefore, our results contribute to the development of sustainable food safety strategies.

Detection of small- and large-for-gestational age using different combinations of prenatal and postnatal charts

OBJECTIVE

To determine the extent to which the detection rate of small-for-gestational age (SGA) and large-for-gestational age (LGA) at birth is influenced by the use of different combinations of estimated-fetal-weight (EFW) and birth-weight (BW) charts.

METHODS

This was a cohort study of all pregnant women with a singleton term birth receiving care in a university hospital during a 3-year period. All participants underwent a universal 36-week ultrasound scan for EFW measurement and had BW recorded at delivery. Five different reference charts were used for EFW and BW centile calculation. Two-by-two contingency tables were constructed using EFW as the screening test variable and BW as the outcome variable in order to calculate sensitivity, specificity, positive predictive value (PPV) and negative predictive value for all possible chart combinations.

RESULTS

The cohort included 17 678 pregnancies. The sensitivity of EFW < 10^th centile for the detection of BW < 10^th centile ranged from 10.8% to 66.8% and the sensitivity of EFW < 3^rd centile for the detection of BW < 3^rd centile ranged from 4.1% to 66.8%, depending on the charts used. The sensitivity of EFW > 90^th centile for BW > 90^th centile ranged between 22.9% and 68.3%. When locally derived charts for EFW and BW were used, the sensitivity of detection of BW < 10^th centile using EFW < 10^th centile was 43.7% (PPV, 45.5%); for the detection of BW < 3^rd centile using EFW < 3^rd centile, the sensitivity was 25.6% (PPV, 26.7%) and, for the detection of BW > 90^th centile using EFW > 90^th centile, it was 49.6% (PPV, 49.0%).

CONCLUSIONS

Different combinations of EFW and BW charts can yield vastly different detection rates (sensitivity) in the same population cohort and time period. If SGA and LGA detection rates are to be used as a meaningful performance indicator, healthcare systems should follow a clear and predefined methodology that includes explicit definitions of common reference standards. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Social and non-social gaze cueing in autism spectrum disorder, attention-deficit/hyperactivity disorder and a comorbid group

Recent trends in literature, along with the changes to the Diagnostic and Statistical Manual (DSM), make it imperative to study Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) together, in order to better understand potential aetiological commonalities between these highly comorbid disorders. The present study examines social cueing, a highly studied construct in ASD, and intra-subject variability (ISV), a potential endophenotype of ADHD, in four groups of typically developing (TD), ADHD, ASD- (ASD without ADHD), ASD+ (ASD with ADHD) participants (N = 85) aged 10-13 years. Results showed that social cueing is intact in the 'pure' ASD group when task expectations are clear. The ADHD group showed faster saccadic reaction times, no increased ISV and a pattern of viewing comparable to the TD group. However, the ASD + group showed a differences in processing style and ISV. A secondary analysis gives evidence of non-additive effects of the ASD and ADHD factors.

Visual search in ADHD, ASD and ASD + ADHD: overlapping or dissociating disorders?

Recent debates in the literature discuss commonalities between Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) at multiple levels of putative causal networks. This debate requires systematic comparisons between these disorders that have been studied in isolation in the past, employing potential markers of each disorder to be investigated in tandem. The present study, choose superior local processing, typical to ASD, and increased Intra-Subject Variability (ISV), typical to ADHD, for a head-to-head comparison of the two disorders, while also considering the comorbid cases. It directly examined groups of participants aged 10-13 years with ADHD, ASD with (ASD+) or without (ASD-) comorbid ADHD and a typically developing (TD) group (total N = 85). A visual search task consisting of an array of paired words was designed. The participants needed to find the specific pair of words, where the first word in the pair was the cue word. This visual search task was selected to compare these groups on overall search performance and trial-to-trial variability of search performance (i.e., ISV). Additionally, scanpath analysis was also carried out using Recurrence Quantification Analysis (RQA) and the Multi-Match Model. Results show that only the ASD- group exhibited superior search performance; whereas, only the groups with ADHD symptoms showed increased ISV. These findings point towards a double dissociation between ASD and ADHD, and argue against an overlap between ASD and ADHD.

Left ventricular global longitudinal peak strain deterioration in patients undergoing endovascular repair of abdominal aortic aneurysms: the effect of arterial stiffness

Purpose

Invasive abdominal aortic aneurysm (AAA) replacement with an endograft interposes between the normal arterial tree which may acutely reduce overall systemic compliance and increase the input impedance. We evaluated the impact of aortic reconstruction, using currently available grafts and endografts, on pulse wave velocity (pwv) and its effect on early cardiac systolic function indices in these patients.

Methods

A total of 73 men, mean age 70±8 years, were evaluated. Of these, 61 underwent endovascular repair (EVAR) and 12 open repair (OS). All patients underwent an assessment with a standard conventional transthoracic and a two-dimensional speckle tracking echocardiography at baseline, at 1 and 6 months after the intervention. Carotid - femoral (c-f) artery waveforms were measured and pwv was determined in all participants on each follow up visit.

Results

No significant changes in blood pressure were observed during the study period. Notably, our findings revealed a significant reduction in global longitudinal peak strain (GLPS) during the 6 months follow-up (from −19.7±−5.9% at baseline to −17.1±−5.9% at 6 months, p=0.03). C-r pwv showed a significant increase 6 months after the procedure (from 10.7±−2.9 m/sec at baseline to 13.9±3.3 m/sec at 6 months, p&lt;0.001). A significant time effect was found on cf-pwv, which showed an increase at 1 month and remained thereafter (p=0.007). Additionally, a deterioration in GLS values was revealed, with a significant increase at 1 month that persisted 5 months later (p&lt;0.001). No significant group effect was observed between EVAR and open repair (p=0.98) and there was no significant interaction (p=0.96). Notably, the difference of global longitudinal strain (ΔGLS) between baseline and 6 months significantly correlated with the corresponding changes in cf-pwv (r=0.494, p&lt;0.0001).

Conclusions

AAA repair not only leads to an increase in aortic stiffness, as measured by the increase in pwv, but also reduces cardiac systolic function. Our findings highlight the need a more intense cardiac surveillance program after aortic reconstruction. Further studies are needed to investigate how this may translate into long-term manifestations of cardiovascular complications and symptomatology.

Funding Acknowledgement

Type of funding source: None

Studying global processing in autism and attention-deficit/hyperactivity disorder with gaze movements: The example of a copying task

Recent discussions in the literature, along with the revision of the Diagnostic and Statistical Manual (DSM) (American Psychiatric Association 2013), suggest aetiological commonalities between the highly comorbid Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD). Addressing this discussion requires studying these disorders together by comparing constructs typical to each of them. In the present study, we investigate global processing, known to be difficult for participants with ASD, and Intra-Subject Variability (ISV), known to be consistently increased in participants with ADHD, in groups, aged 10–13 years, with ADHD (n = 25), ASD without comorbid ADHD (ASD-) (n = 13) and ASD with ADHD (ASD+) (n = 18) in comparison with a typically developing group (n = 22). A Copying task, typically requiring global processing and in this case particularly designed using equally complex stimuli to also measure ISV across trials, was selected. Oculomotor measures in this task proved to be particularly sensitive to group differences. While increased ISV was not observed in the present task in participants with ADHD, both ASD groups looked longer on the figure to be drawn, indicating that global processing takes longer in ASD. However, the ASD+ group fixated on the figure only between drawing movements, whereas the ASD- group did this throughout the drawing process. The present study provides evidence towards ASD and ADHD being separate, not-overlapping, disorders. Since the pure ASD- group was affected more by central coherence problems than the ASD+ group, it may suggest that neuropsychological constructs interact differently in different clinical groups and sub-groups.

Paraoxonase-1: Characteristics and Role in Atherosclerosis and Carotid Artery Disease

Paraoxonase-1 (PON-1) is a calcium-dependent enzyme that is synthesized in the liver and then secreted in blood where it is bound to high density lipoprotein (HDL). PON-1 is a hydrolase with a wide range of substrates, including lipid peroxides. It is considered responsible for many of the antiatherogenic properties of HDL. PON-1 prevents low density lipoprotein (LDL) oxidation, a process that is considered to contribute to the initiation and development of atherosclerosis. PON-1 activity and levels are influenced by gene polymorphisms; of the 2 common variants, one is in position 192 (Q192R) and one in position 55 (M55L). Also, many drugs affect PON-1 activity. The role of PON-1 in carotid atherosclerosis is inconsistent. Some studies show an association of PON-1 polymorphisms with carotid plaque formation, whereas others do not. The aim of this review is to summarize the characteristics of PON-1, its interactions with drugs and its role in atherosclerosis and especially its relationship with carotid artery disease.

An objective scoring method to evaluate image quality of middle cerebral artery Doppler

Objective: To validate an objective scoring system for middle cerebral artery (MCA) pulsed wave Doppler images.Method: From an image database of routine 36-week scans, a random sample of MCA Doppler images was selected. Two reviewers rated the images subjectively as acceptable or unacceptable. Subsequently they used an objective 6-point image scoring system and awarded one point for each of the following: (1) anatomical site, (2) magnification, (3) angle of insonation, (4) image clarity, (5) sweep speed adjustment, and (6) velocity scale and baseline adjustment. Image scores 4-6 were defined as good quality whereas 0-3 as poor. The subjective and objective agreement between the two reviewers was compared using the adjusted Kappa statistic.Results: A total of 124 images were assessed. Using objective scoring the agreement rate between reviewers increased to 91.9% (κ = 0.839) compared to subjective agreement 75.8% (κ = 0.516). The agreement for each criterion was: anatomical site 91.1% (κ = 0.823), magnification 95.2% (κ = 0.903), clarity 83.9% (κ = 0.677), angle 96.0% (κ = 0.919), sweep speed 98.4% (κ = 0.968), and velocity scale and baseline 94.4% (κ = 0.887).Conclusion: Objective assessment of MCA Doppler images using a 6-point scoring system has greater interobserver agreement than subjective assessment and could be used for MCA Doppler quality assurance.

Quality control of ultrasound for fetal biometry: results from the INTERGROWTH-21st Project

OBJECTIVE

To assess a comprehensive package of ultrasound quality control in the Fetal Growth Longitudinal Study of the INTERGROWTH-21^st Project, a large multicenter study of fetal growth.

METHODS

Quality control (QC) measures were performed for 20 313 ultrasound scan images obtained prospectively from 4321 fetuses at 14-41 weeks' gestation in eight geographical locations. At the time of each ultrasound examination, three fetal biometric variables (head circumference (HC), abdominal circumference (AC) and femur length (FL)) were measured in triplicate on separately generated images. All measurements were taken in a blinded fashion. QC had two elements: (1) qualitative QC: visual assessment by sonographers at each study site of their images based on specific criteria, with 10% of images being re-assessed at the Oxford-based Ultrasound Quality Unit (compared using an adjusted kappa statistic); and (2) quantitative QC: assessment of measurement data by comparing the first, second and third measurements (intraobserver variability), remeasurement of caliper replacement in 10% (interobserver variability), both by Bland-Altman plots and plotting frequency histograms of the SD of triplicate measurements and assessing how many were above or below 2 SD of the expected distribution. The system allowed the sonographers' performances to be monitored regularly.

RESULTS

A high level of agreement between self- and external scoring was demonstrated for all measurements (κ = 0.99 (95% CI, 0.98-0.99) for HC, 0.98 (95% CI, 0.97-0.99) for AC and 0.96 (95% CI, 0.95-0.98) for FL). Intraobserver 95% limits of agreement (LoA) of ultrasound measures for HC, AC and FL were ± 3.3%, ± 5.6% and ± 6.2%, respectively; the corresponding values for interobserver LoA were ± 4.4%, ± 6.0% and ± 5.6%. The SD distribution of triplicate measurements for all biometric variables showed excessive variability for three of 31 sonographers, allowing prompt identification and retraining.

CONCLUSIONS

Qualitative and quantitative QC monitoring was feasible and highly reproducible in a large multicenter research study, which facilitated the production of high-quality ultrasound images. We recommend that the QC system we developed is implemented in future research studies and clinical practice. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Distinct effects of social motivation on face evaluations in adolescents with and without autism

Individual differences in social motivation have an influence on many behaviours in both clinical and non-clinical populations. As such, social motivation has been identified as a biological trait that is particularly well-suited for dimensional approaches cutting across neuropsychological conditions. In the present paper, we tested whether social motivation had a similar impact in the general population and in a neuropsychological condition characterized by diminished social motivation: Autism Spectrum Disorders (ASD). More precisely, we evaluated the effect of social motivation on face evaluations in 20 adolescents with ASD and 20 matched controls using avatars parametrically varying in dominance and trustworthiness. In line with previous research, we found in the control group that participants with higher levels of social motivation relied more on perceived trustworthiness when producing likeability judgments. However, this pattern was not found in the ASD group. Social motivation thus appears to have a different effect in ASD and control populations, which raises questions about the relevance of subclinical or non-clinical populations to understand ASD.

Shared mechanism for emotion processing in adolescents with and without autism

Although, the quest to understand emotional processing in individuals with Autism Spectrum Disorders (ASD) has led to an impressive number of studies, the picture that emerges from this research remains inconsistent. Some studies find that Typically Developing (TD) individuals outperform those with ASD in emotion recognition tasks, others find no such difference. In this paper, we move beyond focusing on potential group differences in behaviour to answer what we believe is a more pressing question: do individuals with ASD use the same mechanisms to process emotional cues? To this end, we rely on model-based analyses of participants’ accuracy during an emotion categorisation task in which displays of anger and fear are paired with direct vs. averted gaze. Behavioural data of 20 ASD and 20 TD adolescents revealed that the ASD group displayed lower overall performance. Yet, gaze direction had a similar impact on emotion categorisation in both groups, i.e. improved accuracy for salient combinations (anger-direct, fear-averted). Critically, computational modelling of participants’ behaviour reveals that the same mechanism, i.e. increased perceptual sensitivity, underlies the contextual impact of gaze in both groups. We discuss the specific experimental conditions that may favour emotion processing and the automatic integration of contextual information in ASD.

Osteosynthesis for clavicle fractures: How close are we to penetration of neurovascular structures?

INTRODUCTION

Risks associated with drill plunging are well recognised in clavicle osteosynthesis. To date no studies have described plunge depth associated with clavicle osteosynthesis.

PRIMARY AIM

To determine whether plunge depth associated with clavicle osteosynthesis is great enough to penetrate neurovascular structures and whether surgical experience reduces the risk of neurovascular injury METHOD: Cadaveric clavicles were pressed into spongy phenolic foam to allow measurement of drill bit penetration beyond the far cortex (plunge depth). 15 surgeons grouped according to experience were asked to drill a single hole in the medial, middle and lateral clavicle in 2 specimens each. Each surgeon used fully a charged standard Stryker drill with a new 2.6mm drill bit and guide. Plunge depths were measured in 0.5mm increments. Depth measurements were compared amongst groups and to previously documented distances to neurovascular structures as outlined by Robinson et al. Kruskal-Wallis test was used for overall comparison and Mann-Whitney U test was used for comparing the groups individually.

RESULTS

Mean plunge depth across all groups was 3.4mm, (0.5-6.5), 4.0mm (1mm-8.5mm) and 4.0mm (0.5mm-15mm) in the medial, middle and lateral clavicle. Plunge depths were greater than previously documented distances to the subclavian vein at the medial clavicle on nine occasions. Plunge depths in the middle and lateral clavicle were well within the previously documented distances from neurovascular structures. There was no correlation between level of experience and median plunge depth (p=0.18). However, inexperienced surgeons plunged 1mm greater than intermediate and experienced surgeons (p=0.026). There was one significant outlier; a 15mm plunge depth by an inexperienced surgeon in the lateral clavicle.

CONCLUSION

Clavicle osteosynthesis has a relatively high risk of neurovascular injury. Plunge depths through the clavicle often exceed the distance of neurovascular structures, especially in the medial clavicle. A thorough understanding of the anatomy of these neurovascular structures and methods to prevent excessive plunging is important prior to undertaking clavicle osteosynthesis.

Spontaneous Facial Mimicry is Modulated by Joint Attention and Autistic Traits

Joint attention (JA) and spontaneous facial mimicry (SFM) are fundamental processes in social interactions, and they are closely related to empathic abilities. When tested independently, both of these processes have been usually observed to be atypical in individuals with autism spectrum conditions (ASC). However, it is not known how these processes interact with each other in relation to autistic traits. This study addresses this question by testing the impact of JA on SFM of happy faces using a truly interactive paradigm. Sixty-two neurotypical participants engaged in gaze-based social interaction with an anthropomorphic, gaze-contingent virtual agent. The agent either established JA by initiating eye contact or looked away, before looking at an object and expressing happiness or disgust. Eye tracking was used to make the agent's gaze behavior and facial actions contingent to the participants' gaze. SFM of happy expressions was measured by Electromyography (EMG) recording over the Zygomaticus Major muscle. Results showed that JA augments SFM in individuals with low compared with high autistic traits. These findings are in line with reports of reduced impact of JA on action imitation in individuals with ASC. Moreover, they suggest that investigating atypical interactions between empathic processes, instead of testing these processes individually, might be crucial to understanding the nature of social deficits in autism. Autism Res 2016, 9: 781-789. © 2015 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research.

Focal aorto-iliac atherosclerosis amenable to endovascular interventions though considered benign carry a significant risk of cardiovascular mortality: clinical investigation

AIM

Peripheral arterial disease (PAD) manifested as claudication is surprisingly stable regarding limb deterioration but may indicate increased risk for cardiovascular events and death. We examined whether focal atherosclerotic iliac lesions (TransAtlantic InterSociety Consensus for The Management of Peripheral Arterial Disease-TASC II Type A,B) undergoing endovascular procedures indicate a high risk for limb and life and what is the effect of atherosclerotic risk factors in the rate of adverse outcomes.

METHODS

We examined patients undergoing iliac endovascular interventions due to TASC II Type A,B lesions causing disabling claudication during a 10-year period. Outcome in terms of limb condition and total mortality during short and long-term follow-up was evaluated.

RESULTS

One-hundred thirty-nine patients and one-hundred seventy limbs were examined. Median follow-up was 4.3 years. There were 100 (58.8%) limbs with Type A and 70 (41.2%) with Type B lesions. Primary patency was 81.2% and secondary patency 92.4%. One-hundred fifteen (67.6%) limbs were improved whereas 42 (24.7%) remained stable and 13 (7.7%) deteriorated during long-term follow-up. Major amputation was performed in 2 and minor amputation in 2 limbs resulting in 2.4% total amputation rate. Overall mortality was 22.6% and 64.5% of all deaths represented cardiovascular events. Statistical analysis revealed significant relations of total mortality with hyperlipidemia and diabetes.

CONCLUSION

Endovascular treatment of localized iliac lesions offers good long-term results regarding patency, clinical improvement and limb salvage. Nevertheless, even focal atherosclerosis indicates a significant risk of cardiovascular mortality. Modification of atherosclerotic risk factors early in the course of PAD may be beneficial for these patients.

Fetal biometry: how well can offline measurements from three-dimensional volumes substitute real-time two-dimensional measurements?

OBJECTIVES

To assess the feasibility, accuracy and reproducibility of manipulating three-dimensional (3D) volume sets in order to reconstruct optimal two-dimensional (2D) planes for fetal biometry throughout gestation and compare them with those derived from real-time 2D scanning.

METHODS

Sixty-five fetuses were evaluated at a gestational age of 14-41 weeks. For each fetus a duplicate set of seven standard fetal measurements was taken by an experienced operator using 2D ultrasound and then 20 intentionally suboptimal 3D volumes from different predefined angles were captured and stored. These were manipulated and measured. The time taken to complete a full scan, with both 2D and 3D ultrasound, was recorded. All measurement differences were expressed as gestational age-specific Z-scores. For all comparisons Bland-Altman plots were used and limits of agreement were calculated. The means and variances of the measurements were tested with a paired t-test and Pitman's test for differences in variance, respectively. The difference between the time taken to perform a 2D and a 3D scan was tested using the Wilcoxon signed-ranks test.

RESULTS

Mean agreement between 2D and 3D ultrasound measurements was good, with no statistically significant differences (i.e. no systematic error) unless the head was facing anteroposteriorly, or the long axis of the femur was at 60-90° to the transducer. The variance (random error) for 3D measurements was similar to that for 2D measurements. Planes from some volumes could not be extracted (7% for head circumference, 9% for abdominal circumference and 11% for femur length). The median time required to perform a full fetal biometric scan was significantly higher for 3D than for 2D (3:04 min vs 1:57 min, respectively; P < 0.001).

CONCLUSIONS

Fetal measurements derived from 3D volume acquisitions exhibited good agreement with those obtained by real-time 2D scanning, with no extra systematic or random error. However, they were slower to obtain, not all volumes were amenable to extraction of planes and measurements that came from a head facing anteroposteriorly or that were obtained with the long axis of the femur at 60-90° to the transducer were systematically smaller.

Ultrasound methodology used to construct the fetal growth standards in the INTERGROWTH-21st Project

A unified protocol is essential to ensure that fetal ultrasound measurements taken in multicentre research studies are accurate and reproducible. This paper describes the methodology used to take two-dimensional, ultrasound measurements in the longitudinal, fetal growth component of the INTERGROWTH-21(st) Project. These standardised methods should minimise the systematic errors associated with pooling data from different study sites. They represent a model for carrying out similar research studies in the future.

Standardisation and quality control of ultrasound measurements taken in the INTERGROWTH-21st Project

Meticulous standardisation and ongoing monitoring of adherence to measurement protocols during data collection are essential to ensure consistency and to minimise systematic error in multicentre studies. Strict ultrasound fetal biometric measurement protocols are used in the INTERGROWTH-21(st) Project so that data of the highest quality from different centres can be compared and potentially pooled. A central Ultrasound Quality Unit (USQU) has been set up to oversee this process. After initial training and standardisation, the USQU monitors the performance of all ultrasonographers involved in the project by continuously assessing the quality of the images and the consistency of the measurements produced. Ultrasonographers are identified when they exceed preset maximum allowable differences. Corrective action is then taken in the form of retraining or simply advice regarding changes in practice. This paper describes the procedures used, which can form a model for research settings involving ultrasound measurements.

Standardisation of crown-rump length measurement

Correct estimation of gestational age is essential for any study of ultrasound biometry and for everyday clinical practice. However, inconsistency in pregnancy dating may occur through differences in measurement methods or errors during measurement. In the INTERGROWTH-21(st) Project, pregnancies are dated by the last menstrual period, provided that it is certain and associated with a regular menstrual cycle, and the gestational age by dates concurs with a first-trimester ultrasound crown-rump length (CRL) estimation. Hence, there was a need to standardise CRL measurement methodology across the study sites in this international, multicentre project to avoid systematic differences in dating. To achieve uniformity we undertook the following steps: the ultrasound technique was standardised by disseminating an illustrated, operating manual describing CRL plane landmarks and calliper application, and posters describing the correct acquisition technique were disseminated for quick reference. To ensure that all ultrasonographers understood the methodology, they forwarded a log-book to the INTERGROWTH-21(st) Ultrasound Coordinating Unit, containing the answers to a written test on the manual material and five images of a correctly acquired CRL. Interpretation of CRL was also standardised by ensuring that the same CRL regression formula was used across all study sites. These methods should minimise potential systematic errors in dating associated with pooling data from different health institutions, and represent a model for standardising CRL measurement in future studies.

The effect of maternal vitamin D concentration on fetal bone

CONTEXT

Vitamin D deficiency during pregnancy may be associated with suboptimal fetal growth, but direct evidence is lacking.

OBJECTIVES

The aim of the study was to validate a method for fetal femur volume (FV) measurement using three-dimensional ultrasound and to detect correlations between FV and maternal vitamin D concentration.

DESIGN, SETTING, AND PARTICIPANTS

A novel method for assessing FV consists of three ultrasound measurements-femur length, proximal metaphyseal diameter (PMD), and midshaft diameter-and a volume equation; this was validated by comparing ultrasound to computed tomography measurements in six pregnancies after mid-trimester termination. This method was then applied in a cohort of healthy pregnant women participating in the Southampton Women Survey. Fetal three-dimensional ultrasound and maternal 25-hydroxyvitamin D [25(OH)D] levels were performed at 34 wk; dual-energy x-ray absorptiometry of the newborn was performed shortly after birth. Univariate and multiple linear regression analyses were performed between maternal characteristics and fetal outcomes.

MAIN OUTCOME MEASURES

We performed ultrasound measurements of the fetal femur.

RESULTS

In 357 pregnant participants, serum 25(OH)D correlated significantly with FV (P = 0.006; r = 0.147) and PMD (P = 0.001; r = 0.176); FV also demonstrated positive univariate correlations with maternal height (P < 0.001; r = 0.246), weight (P = 0.003; r = 0.160), triceps skinfold thickness (P = 0.013; r = 0.134), and a borderline negative effect from smoking (P = 0.061). On multiple regression, independent predictors of FV were the maternal height and triceps skinfold thickness; the effect of 25(OH)D on FV was attenuated, but it remained significant for PMD.

CONCLUSION

Using a novel method for assessing FV, independent predictors of femoral size were maternal height, adiposity, and serum vitamin D. Future trials should establish whether pregnancy supplementation with vitamin D is beneficial for the fetal skeleton, using FV and PMD as fetal outcome measures.

Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size

BACKGROUND

Reliable ultrasound charts are necessary for the prenatal assessment of fetal size, yet there is a wide variation of methodologies for the creation of such charts.

OBJECTIVE

To evaluate the methodological quality of studies of fetal biometry using a set of predefined quality criteria of study design, statistical analysis and reporting methods.

SEARCH STRATEGY

Electronic searches in MEDLINE, EMBASE and CINAHL, and references of retrieved articles.

SELECTION CRITERIA

Observational studies whose primary aim was to create ultrasound size charts for bi-parietal diameter, head circumference, abdominal circumference and femur length in fetuses from singleton pregnancies.

DATA COLLECTION AND ANALYSIS

Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was given to each study. Multiple regression analysis between quality scores and study characteristics was performed.

MAIN RESULTS

Eighty-three studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'Inclusion/exclusion criteria', as none of the studies defined a rigorous set of antenatal or fetal conditions which should be excluded from analysis; 'Ultrasound quality control measures', as no study demonstrated a comprehensive quality assurance strategy; and 'Sample size calculation', which was apparent in six studies only. On multiple regression analysis, there was a positive correlation between quality scores and year of publication: quality has improved with time, yet considerable heterogeneity in study methodology is still observed today.

CONCLUSIONS

There is considerable methodological heterogeneity in studies of fetal biometry. Standardisation of methodologies is necessary in order to make correct interpretations and comparisons between different charts. A checklist of recommended methodologies is proposed.

Intra- and interobserver variability in fetal ultrasound measurements

OBJECTIVE

To assess intra- and interobserver variability of fetal biometry measurements throughout pregnancy.

METHODS

A total of 175 scans (of 140 fetuses) were prospectively performed at 14-41 weeks of gestation ensuring an even distribution throughout gestation. From among three experienced sonographers, a pair of observers independently acquired a duplicate set of seven standard measurements for each fetus. Differences between and within observers were expressed in measurement units (mm), as a percentage of fetal dimensions and as gestational age-specific Z-scores. For all comparisons, Bland-Altman plots were used to quantify limits of agreement.

RESULTS

When using measurement units (mm) to express differences, both intra- and interobserver variability increased with gestational age. However, when measurement of variability took into account the increasing fetal size and was expressed as a percentage or Z-score, it remained constant throughout gestation. When expressed as a percentage or Z-score, the 95% limits of agreement for intraobserver difference for head circumference (HC) were ± 3.0% or 0.67; they were ± 5.3% or 0.90 and ± 6.6% or 0.94 for abdominal circumference (AC) and femur length (FL), respectively. The corresponding values for interobserver differences were ± 4.9% or 0.99 for HC, ± 8.8% or 1.35 for AC and ± 11.1% or 1.43 for FL.

CONCLUSIONS

Although intra- and interobserver variability increases with advancing gestation when expressed in millimeters, both are constant as a percentage of the fetal dimensions or when reported as a Z-score. Thus, measurement variability should be considered when interpreting fetal growth rates.

A review of fetal volumetry: the need for standardization and definitions in measurement methodology

Volume charts of fetal organs and structures vary considerably among studies. This review identified 42 studies reporting normal volumes, namely for fetal brain (n = 3), cerebellum (n = 4), liver (n = 6), femur (n = 2), lungs (n = 15), kidneys (n = 3) and first-trimester embryo (n = 9). The differences among median volumes were expressed both in percentage form and as standard deviation scores. Wide discrepancies in reported normal volumes make it extremely difficult to diagnose pathological organ growth reliably. Given its magnitude, this variation is likely to be due to inconsistencies in volumetric methodology, rather than population differences. Complicating factors include the absence of clearly defined anatomical landmarks for measurement; inadequate assessment and reporting of method repeatability; the inherent difficulty in validating fetal measurements in vivo against a reference standard; and a multitude of mutually incompatible three-dimensional (3D) imaging formats and software measuring tools. An attempt to standardize these factors would improve intra- and inter-researcher agreement concerning reported volumetric measures, would allow generalization of reference data across different populations and different ultrasound systems, and would allow quality assurance in 3D fetal biometry. Failure to ensure a quality control process may hamper the wide use of 3D ultrasound.

Standardization of fetal ultrasound biometry measurements: improving the quality and consistency of measurements

OBJECTIVE

To assess whether a standardization exercise prior to commencing a fetal growth study involving multiple sonographers can reduce interobserver variation.

METHODS

In preparation for an international study assessing fetal growth, nine experienced sonographers from eight countries participated in a standardization exercise consisting of theoretical and practical sessions. Each performed a set of seven standard fetal measurements on pregnant volunteers at 20-37 weeks' gestation, and these were repeated by the lead sonographer; all measurements were taken in a blinded fashion. After this the sonographers had hands-on practice and feedback sessions on other volunteers. This process was repeated three times. Measurement differences between sonographers and the lead sonographer, expressed as a gestational-age-specific Z-score, between the first and third scans were compared using the Wilcoxon signed ranks test, and variance was assessed using Pitman's test. Interobserver agreement was also assessed using the intraclass correlation coefficient (ICC), and all images were scored for quality in a blinded fashion.

RESULTS

At baseline the level of agreement and image scoring were high. A significant reduction in the differences between sonographers and the lead sonographer were seen for fetal biometry overall (head circumference, abdominal circumference and femur length) between the first and third scans (median Z-scores, 0.46 and 0.24; P = 0.005), and a reduction in the variance was also observed (P < 0.001). The ICCs for measurement pairs for every fetal measurement showed a clear trend of increasing ICC (better agreement) with consecutive training scan sessions, although no improvement in image scores was seen.

CONCLUSION

Even for experienced sonographers, a standardization exercise before starting a study of fetal biometry can improve consistency of measurements. This could be of relevance for studies assessing fetal growth in multicenter sites.

Studying the expansion of small abdominal aortic aneurysms: is there a role for peak wall stress?

AIM

The aim of this paper was to study the characteristics of three distending small abdominal aortic aneurysms (AAAs), with an increase in maximal diameter from 5 to 5.5 cm or above.

METHODS

Peak Wall Stress (PWS) in the presence and absence of intraluminal thrombus (ILT) was evaluated in 3 cases of small AAAs (5 cm), at initial presentation and after their expansion, at maximum diameters ≥5.5 cm using finite element analysis. Furthermore, AAA sac volume (Vsac), the percentage volume of ILT (ILT%) and the percentage change of Vsac (ΔV%) and ILT (ILT%) were estimated and the location of PWS was recorded.

RESULTS

Two AAA expanded from 5cm to 5.5 cm in a period of 6 months after initial presentation, with increase of sac volume by 20% and 30%, respectively. The third AAA expanded to a diameter of 6.5 cm after a follow-up period of 13 months, with a subsequent increase in sac volume of 78%. The expansion of AAA max diameter did not correlate with differences in peak wall stress (PWS) values at the initial presentation, ranging from 20.5 to 21.3 Nt/cm2.

CONCLUSION

PWS values cannot solely serve as a predictive tool for small AAA expansion. Small AAA expansion seem to be a multifactorial process, not solely described by PWS values but rather by a combination of mechanical, hemodynamic and biological factors.

Surface area measurement using rendered three-dimensional ultrasound imaging: an in-vitro phantom study

OBJECTIVE

Cranial sutures and fontanelles can be reliably demonstrated using three-dimensional (3D) ultrasound with rendering. Our objective was to assess the repeatability and validity of fontanelle surface area measurement on rendered 3D images.

METHODS

This was an in-vitro phantom validation study. Four holes, representing fontanelles, were cut on a flat vinyl tile. The phantom was scanned in a test-tank by two sonographers, at four different depths and using two different 3D sweep directions. The surface areas were measured on scan images and also directly from the phantom for comparison. Coefficients of variation (CVs), intraclass correlation coefficients (ICCs) and Bland-Altman plots were used for repeatability analysis. Validity was expressed as the percentage difference of the measured area from the true surface area.

RESULTS

Validity of measurement was satisfactory with a mean percentage difference of - 5.9% (median = - 3.5%). The 95% limits of agreement were - 23.9 to 12.1%, suggesting that random error is introduced during image generation and measurement. Repeatability of caliper placement on the same image was higher (intraobserver CV = 1.6%, ICC = 0.999) than for measurement of a newly generated scan image (intraobserver CV = 5.5%, ICC = 0.992). Reduced accuracy was noted for the smallest shape tested.

CONCLUSION

Surface area measurements on rendered 3D ultrasound images are accurate and reproducible in vitro.

Diagnosis and management of vasa previa: a questionnaire survey

OBJECTIVES

Our aim was to assess the current use of obstetric ultrasound imaging for the diagnosis of asymptomatic vasa previa. We also investigated obstetricians' views on the feasibility of a screening policy and their awareness of risk factors associated with this condition.

METHODS

A national postal survey was conducted between March and July 2006. A total of 234 questionnaires were sent to obstetric and fetomaternal consultants across England and Wales. In all, 128 questionnaires were returned, a response rate of 55%.

RESULTS

Most respondents (85%) stated that in their hospital they do not report velamentous cord insertions at the anomaly scan. However, 73% occasionally or routinely document the presence of succenturiate lobes. Only 33% of respondents offered transvaginal scanning for the identification of vasa previa within their hospital, whereas only 6% had ever referred women to a tertiary center for this indication. In all, 34% of the respondents did not identify any risk factor for the condition. Most respondents (80%) would offer an elective Cesarean section if vasa previa was suspected antenatally; the majority would perform it at 38 weeks' gestation. However, only 20% of respondents felt that an effective screening policy is possible.

CONCLUSIONS

Despite evidence that perinatal death can be prevented by antenatal diagnosis of vasa previa, most obstetricians in England and Wales feel that a screening policy is not possible. The majority of them would offer an elective Cesarean section for vasa previa at around 38 weeks. There is a need to increase awareness and understanding of the major risk factors for this condition.

Clinical presentation and anatomic distribution of chronic venous insufficiency of the lower limb in a typical Mediterranean population

BACKGROUND

The aim of this study was to demonstrate the characteristics of lower limb chronic venous insufficiency (CVI) in a homogeneous Mediterranean population.

METHODS

Investigation of 694 patients with uni- or bilateral symptoms and signs of lower limb CVI using colour duplex scanning. Limbs with previous venous surgery were excluded. The limbs were classified according to history and ultrasonic findings into those with post-thrombotic and those with primary CVI. The clinical presentation according to the CEAP classification was correlated to the anatomic distribution of venous reflux.

RESULTS

Most of the symptomatic limbs (537/656, 81.5%) with primary CVI belonged to classes 1 to 3. In these limbs reflux confined to superficial veins was very common (64.5%, 424/656) whereas the prevalence of deep and perforator vein reflux was 18.5 and 25.5%, respectively. In contrast most of the limbs (69.5%) with post-thrombotic CVI belonged to classes 4 to 6, had a complex pattern of reflux, and involvement of deep and perforator veins was common (86.5 and 48%, respectively). In about a quarter (24%) of patients with suspected primary CVI no reflux was found in either limb on duplex scanning. Most of them (48%) had telangiectasis. Bilateral reflux was found in 71% of the patients with primary CVI.

CONCLUSIONS

The clinical presentation was worse in limbs with post-thrombotic CVI than in those with a primary disease. Post-thrombotic CVI was associated with a complex pattern of reflux, affecting mostly the deep and perforator veins, whereas superficial reflux was the most common pattern in limbs with primary CVI. Therefore, surgery aiming to eliminate superficial reflux would confer only a minimal benefit in limbs with post-thrombotic CVI but would treat the majority of the limbs with the primary CVI. The high prevalence of bilateral reflux found in patients with primary CVI suggests a bilateral predisposition, which supports the hypothesis of the existence of a generalised venous disease.

The application of fast gradient capillary liquid chromatography/mass spectrometry to the analysis of pharmaceuticals in biofluids

Fast gradient capillary high performance liquid chromatography (HPLC) coupled to a mass spectrometer has been successfully used for the analysis of pharmaceutical compounds from biological matrices, in the femtogram on column range. In the work reported in this paper, the use of capillary HPLC, on the 180-micron internal diameter scale, has shown a 30-fold improvement in detection limits when compared to conventional 2-mm scale chromatography. The use of fast gradient elution resulted in a generic methodology which gave excellent chromatographic reproducibility and column longevity. This technique has been used in conjunction with simple protein precipitation, with no deleterious effect on either the column life or the chromatographic performance. The use of capillary HPLC in bioanalysis has the potential to give a significant increase in assay sensitivity with the equipment currently in use. In this paper the authors also present a modification to the current PE-Sciex ion-spray source which allows excellent spray adjustment in three dimensional accessibility, which is important when working with low flow rates, as well as reducing the inherent system dead volume.

Purification of cord blood lymphocytes

When cord blood is separated using standard methods based on Ficoll-Hypaque, the mononuclear fraction is contaminated with erythrocytes and also with nucleated cells that do not express the leucocyte marker CD45. The contamination with CD45-negative cells can exceed 50%, and will interfere with phenotypic, mRNA or functional analysis. A large proportion of these cells are erythrocyte precursors. The contaminating cells may be removed by lysis with hypotonic ammonium chloride; when the cells are required for studies which are adversely affected by ammonium chloride (such as antigen processing), high purity can be attained by two rounds of density separation.

Human progelatinase A can be activated by autolysis at a rate that is concentration-dependent and enhanced by heparin bound to the C-terminal domain

Activation of the latent precursor of human gelatinase A (progelatinase A) was investigated using recombinant proenzyme purified from culture medium conditioned by transfected mouse myeloma cells. A 4.0 microM progelatinase A solution was activated to a maximum of 48% of the activity produced by 4-aminophenylmercuric acetate (APMA) simply by its incubation at 37 degrees C for 12 h, though at lower starting concentrations the rate and extent of activation were reduced. Activation was shown to be the result of a single autolytic cleavage at the Asn80-Tyr81 peptide bond that removes the propeptide and converts the M(r) = 72,000 proenzyme into the M(r) = 66,000 active species also produced by APMA activation. It is proposed that this cleavage is a bimolecular event catalysed by previously activated gelatinase A. The addition of heparin increased by approximately eightfold the initial rate of progelatinase A autolytic activation but did not affect the activation of a deletion mutant that lacked the C-terminal domain [des-(418-631)progelatinase A]. The inference that this increase resulted from an interaction between heparin and the C-terminal domain was supported by the finding that, unlike des-(418-631)gelatinase A, both full-length gelatinase A and the isolated C-terminal domain were able to bind to heparin-Sepharose CL-6B and that, at NaCl concentrations sufficient to abolish this binding, heparin had no effect. We conclude that heparin is able to enhance autolytic activation by acting as a template that approximates active-->latent gelatinase A and suggest that a similar mechanism may account for the cell-surface activation of this enzyme.

The 28-kDa N-terminal domain of mouse stromelysin-3 has the general properties of a weak metalloproteinase

The putative matrix metalloproteinase mouse stromelysin-3 was expressed from Escherichia coli and from a mouse myeloma cell line. In the former case a single major protein of 58-kDa was detectable by immunoblotting, but no proteolytic activity could be elicited by zymography or trypsin or organomercurial treatment as would be expected for a typical matrix metalloproteinase. In the latter case immunodetectable proteins of 55-58 and 27-28-kDa were produced. The effect of trypsin or organomercurial treatment of the 55-58-kDa forms was to generate a 51-kDa form and lower molecular mass fragments. Upon zymographic analysis only the 27-28-kDa forms showed caseinolytic activity. N-terminal sequencing and immunoblotting analysis with antibodies specific to distinct domains of stromelysin-3 indicated that the 27-28-Da stromelysin-3 forms had lost the predicted propeptide and the majority of the C-terminal domain. The purified 28-kDa form of stromelysin-3 could weakly degrade a number of extracellular matrix proteins and was inhibited by TIMP. However, the evidence that mature full-length stromelysin-3 is a metalloproteinase could not be substantiated and the precise role of this protein in vivo remains to be elucidated. By partial analogy with interstitial collagenase, one hypothesis is that stromelysin-3 with an intact C-terminal domain has specific properties for an as yet undefined substrate.