P2743Right ventricular size in repaired tetralogy of Fallot: correlations between transthoracic echocardiography and cardiovascular magnetic resonance

Introduction

Right ventricular (RV) size informs about prognosis and need for pulmonary valve replacement in patients with repaired tetralogy of Fallot (rTOF). Cardiac magnetic resonance (CMR) is considered the reference standard for measurement of RV volumes. Despite known limitations for RV evaluation, 2D transthoracic echocardiography (TTE) remains the primary and most available imaging modality in the rTOF population.

Purpose

To determine which TTE RV size parameters best correlate with CMR-derived indexed RV end-diastolic (RVEDVi) and end-systolic (RVESVi) volumes in the rTOF population. We sought to determine the best TTE measurement thresholds to predict normal RV volume (RVEDVi ≤110 mL/m2) and significant RV dilatation by CMR (RVEDVi ≥150ml/m2).

Method

We retrospectively enrolled all rTOF patients followed at a single-center between 2010 and 2018 who had both TTE and CMR exams performed within a 12-month interval. All TTE exams were reviewed by an observer measuring RV areas, RV inlet and RV outlet at end-diastole and end-systole. Analyses of CMR studies were performed by 3 observers who measured RV area, RV inlet, RV outlet and RV volumes at end-diastole and end-systole. Correlations between TTE and CMR parameters were performed using Pearson correlation coefficients. Using the TTE RV parameters with the strongest correlation with CMR, we subsequently determined thresholds to predict a CMR RVEDVi ≤110ml/m2 and ≥150ml/m2 using ROC analysis.

Results

We enrolled 130 patients (59 women [45%], mean age 43±12.8 years). Median age at TOF repair was 4 [3–6] years; 18 patients (14%) had subsequent pulmonary valve replacement. Median interval between TTE and CMR exams was 114 [59–239] days. There were significant correlations between all TTE parameters and CMR RVEDVi. TTE indexed RV end-diastolic area (RVEDAi) most strongly correlated with CMR RVEDVi (r=0.73, p<0.0001). All TTE RV parameters significantly correlated with CMR RVESVi but indexed RV end-systolic area had the strongest correlation (r=0.77, p<0.0001). ROC analysis performed to predict RVEDVi of ≤110ml/m2 and ≥150ml/m2 using TTE RVEDAi revealed areas under the curve of 0.86±0.04 and 0.90±0.03, respectively. A TTE RVEDAi ≤17cm2/m2 predicted a normal CMR RV volume (≤110ml/m2) with a sensitivity of 90% and a specificity of 74%. A TTE RVEDAi ≥19cm2/m2 predicted a CMR RVEDVi ≥150 mL/m2 with a sensitivity of 93% and a specificity of 76%.

Conclusion

In rTOF patients, both diastolic and systolic TTE RV area best correlate with CMR-derived RV end-diastolic and end-systolic volumes. A cut-off value of TTE RVEDAi of 19cm2/m2 is 93% sensitive and 76% specific to predict a CMR RVEDVi ≥150ml/m2. Simple RV size measurement using TTE may help inform the need and frequency of CMR evaluations in rTOF patients.

Study of hepatic tyrosine aminotransferase from Schistosoma-infected mice

In the current study, tyrosine aminotransferase (TAT) as a target enzyme was purified from the liver of control and Schistosoma-infected mice that was subjected to catalytic investigation. The purified enzyme has a single band on SDS-PAGE with a molecular mass of almost 100 KD from control and infected mice. The kinetic studies of hepatic TAT towards its substrates showed no change in K_m, whereas V_max value was increased from 2.3 to 2.9 fold in the enzyme isolated from Schistsoma- infected mice. In addition, the K_cat/ K_m ratio displayed a higher value for the enzyme from infected mice, indicating that it is more efficient and specific. On the other hand, the in vitro effect of praziquantel showed a slight activation of hepatic TAT in both control and infected mice, whereas mirazid (MZD) has an inhibitory effect in a concentration-dependent manner. The response of TAT from infected mice towards MZD inhibition is less than that from controls. These data suggest that there is a change in the catalytic properties of hepatic TAT in schistosomiasis and the in vitro effect of the schistosomicidal drugs appears to have inductive or inhibitory effect.

Screening of Egyptian toddlers for autism spectrum disorder using an Arabic validated version of M-CHAT; report of a community-based study (Stage I)

BACKGROUND

Although there is a recommendation that toddlers be screened for Autism spectrum disorder (ASD) during their 18- and 24-month well-care child visits, diagnosis often occurs well after the child turns 4 years old. Such delayed diagnosis hinders the implementation of early intervention thus worsens the long-term prognosis of ASD.

OBJECTIVE

The current community-based study in its stage I aimed at early screening of Egyptian toddlers for ASD using an Arabic validated version of Modified Checklist for Autism in Toddlers (M-CHAT).

METHODOLOGY

A cross-sectional community-based descriptive study was carried out enrolling 5546 Egyptian toddlers. They were randomly recruited from those attending Primary Health Care Units in six Egyptian governorates with a fair representation of the urban, semi-urban, and rural Egyptian populations. An Arabic validated version of M-CHAT was used as a screening tool for ASD.

RESULTS

The current study revealed failure of M-CHAT (suspected to have ASD and needs further evaluation) in 1320 out of the enrolled 5546 Egyptian toddlers (23.8%).

CONCLUSION

M-CHAT as a screening tool for ASD has flagged a considerable percent of the enrolled toddlers that necessitates referral for further evaluation (stage II) to settle the diagnosis of ASD in the true positive cases. Perfecting the delicate balance between sensitivity and specificity for ASD screening tools is crucial in order not to miss early detection of ASD cases and at the same time, to avoid over-diagnosis with subsequent abuse of the limited healthcare resources in developing countries.

Identification and characterization of a highly pathogenic H5N1 avian influenza A virus during an outbreak in vaccinated chickens in Egypt

Highly pathogenic avian influenza A (HPAI) H5N1 viruses continue to be a major veterinary and public health problem in Egypt. Continued surveillance of these viruses is necessary to devise strategies to control the spread of the virus and to monitor its evolutionary patterns. This is a report of the identification of a variant strain of HPAI H5N1 virus during an outbreak in 2010 in vaccinated chicken flocks in a poultry farm in Assiut, Egypt. Vaccination of chickens with an oil-emulsified inactivated A/chicken/Mexico/232/94 (H5N2) vaccine induced high levels of hemagglutination inhibition (HI) antibody titers reaching up to 9 log2. However, all flocks irrespective of the number of vaccine doses and the resultant HI titer levels came down with severe influenza infections. The qRT-PCR and rapid antigen test confirmed the influenza virus to be from H5N1 subtype. Sequencing of the hemagglutinin (HA) gene fragment from ten independent samples demonstrated that a single H5N1 strain was involved. This strain belonged to clade 2.2.1 and had several mutations in the receptor-binding site of the HA protein, thereby producing a variant strain of HPAI H5N1 virus which was antigenically different from the parent clade 2.2.1 virus circulating in Egypt at that time. In order to define the variability in HPAI H5N1 viruses over time in Egypt, we sequenced another H5N1 virus that was causing infections in chickens in 2014. Phylogenetic analysis revealed that both viruses had further distanced from the parent virus circulating during 2010. This study highlights that the antigenic mutations in HPAI H5N1 viruses represent a definitive challenge for the development of an effective vaccine for poultry. Overall, the results emphasize the need for continued surveillance of H5N1 outbreaks and extensive characterization of virus isolates from vaccinated and non-vaccinated poultry populations to better understand genetic changes and their implications.