Syncopal patients without prodromes exhibit a diverse pattern of adenosine release during head-up tilt test

Background/Introduction

In a significant proportion of patients with neurally-mediated syncope (NMS), the mechanism of syncope remains largely undetermined. Adenosine has been proposed as a central humoral factor in various forms of NMS: high Adenosine Plasma Levels (ADP) are encountered in patients with vasovagal syncope (VVS), low ADP in non-prodromes syncope (NPS), while ADP in patients with situational syncope SS are less well determined.

Purpose

We sought to assess ADP in patients with different clinical forms of syncope, with an emphasis on the presence or absence of prodromal symptoms, as well as the relation between ADP and the outcomes of Head-Up Tilt Table Test (HUTT) and Adenosine test (ADT).

Methods

Patients with different clinical types of NMS (n=124), i.e., VVS, NPS, or SS, were investigated using a standard protocol including HUTT and ADT. During HUTT, ADP was measured in the supine position, at table tilting, and in syncope.

Results

Baseline ADP did not differ among groups. ADP at syncope were higher in NPS compared to VVS (1.55±1.29 vs 0.16±0.05 μM, p=0.03) and SS (0.15±0.05 μM, p=0.02). In NPS, ADP increased from the supine position to the time of syncope (0.47±0.25 to 1.55±1.29 μM, p=0.04). In VVS, ADP increased only from the supine to the tilt position (0.23±0.04 to 0.35±0.10 μMu, p=0.02), while in SS ADP did not change in any stage of HUTT. SS was associated with cardioinhibitory HUTT (OR 3.40, 95% CI 1.05 to 9.56, p=0.04) and positive ADT (OR 4.22, 95% CI 1.47 to 11.46, p=0.012).

Conclusion(s)

A distinct pattern of ADP increase is noted during HUTT in NPS, suggesting that an excessive increase of ADP may play the key role in triggering this type of clinical presentation of syncope independently of the baseline ADP. Cardioinhibition prevails in patients with SS without clear adenosine involvement. Such observations contribute to an enhanced understanding of the pathophysiology of different clinical forms of syncope which may offer the possibility to tailor the management approach appropriately.

Funding Acknowledgement

Type of funding sources: None.

O-174 The association of chromosomal abnormalities with embryo ultrastructure, spindle anomalies and metabolic profiling

Study question

Can metabolic profiling predict embryos at risk of chromosomal abnormalities and how are these reflected in the ultrustructure and cytoskeleton?

Summary answer

Different metabolic profiles are observed between normal and aneuploid/chaotic embryos which are linked to altered mitochondrial and other organelles’ structure/function and spindle and nuclear abnormalities.

What is known already

One of the greatest challenges in IVF is the selection of the best ‘fit’ embryo for implantation in a non-invasive way. Down’s syndrome embryos and Monosomy 21 embryos have previously been shown to have differential expression of metabolites compared to normal embryos, but limited studies, have investigated in detail the metabolic profiling of embryos with other abnormalities in comparison to chromosomally normal embryos or their reflection in the ultrustructure and the cytoskeleton.

Study design, size, duration

Culture media collected on day 3 from 200 embryos which underwent PGT-A, were analysed by hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS). The chromosomally normal embryos were transferred to the uterus (1–2 embryos/ET) or still remain vitrified for clinical use and 120 of the embryos that were diagnosed with chromosomal abnormalities were either processed for spindle/chromosome configurations analysis (n = 60) by confocal laser scanning microscopy(CLSM) or for ultrastructural analysis (n = 60) by Transmission Electron Microscopy(TEM).

Participants/materials, setting, methods

Metabolic profiling was conducted in a Forensic Toxicology Laboratory by HILIC-MS/MS (100 metabolites). Spindle Chromosome Configuration analysis was conducted in an academic hospital after methanol fixation and immunostaining with α-tubulin, γ-tubulin, acetylated-tubulin antibodies and DAPI or/ PI to visualise DNA. Ultrastructure analysis by TEM was carried out in a Histology/Embryology Laboratory following embryo fixation in 3% glutaraldehyde, 1% osmium tetroxide, washes in  PBS and staining with 1% aqueous uranyl acetate.

Main results and the role of chance

This  study provides screening  for >100 primary metabolites using HILIC-MS/MS in a single run of 40 minutes. Characteristic patient specific metabolic profiles were observed which differed between normal embryos that had resulted in a viable pregnancy and aneuploid and chaotic embryos. Logistic regression analysis revealed a number of metabolites that had a high predictive value including Isoleucine,  lysine and glucose and models were created in combination with embryo score which in the future could serve as non-invasive markers for the detection of chromosomal abnormalities before embryo transfer. TEM analysis revealed differences in the quality of cells and organelle activity which were reflected in the embryo metabolic profiles. Chaotic poor quality embryos showed a lower number of mitochondria, often with no cisternae, increased number of vacuoles, and frequently problems in junctions between cells. Aneuploid but well developed hatching blastocysts had mainly cells with good mitochondrial morphology/ activity, nice Golgi apparatus and well developed rough and smooth endoplasmic reticulum but depending on the aneuploidy involved, inner cell mass cells with limited organelles and occasionally lipofuscin droplets in the trophectoderm were evident. Nuclear and chromosomal abnormalities were interrelated through abnormalities in cytokinesis and spindle formation and reflected in the embryo metabolic profiles.

Limitations, reasons for caution

Although metabolic profiles were compared between normal and chromosomally abnormal embryos identified by PGT-A, all the  normal embryos were transferred to the uterus or remain vitrified for clinical purposes and therefore the ultrastructure analysis and the spindle chromosome configuration analysis are based only on chromosomally abnormal embryos.

Wider implications of the findings

This study identified distinct differences in the metabolic profiles of normal and chromosomally abnormal embryos and provides unique metabolites which in the future could serve as non-invasive biomarkers for the detection of chromosomal abnormalities before embryo transfer.

Trial registration number

not applicable

A hydrophilic interaction liquid chromatography - Tandem mass spectrometry method for the determination of phenylephrine in dried blood spots from preterm infants

A sensitive and accurate hydrophilic interaction liquid chromatography - tandem mass spectrometry method (HILIC-MS/MS) was developed and validated for the determination of phenylephrine concentration in Dried Blood Spot (DBS) samples from preterm infants, after ocular administration of an ophthalmic solution with phenylephrine. Sample preparation involved the extraction of the analyte from an 85 μL DBS sample with methanol - acetonitrile (50:50, v/v). Chromatographic separation was achieved on an ACQUITY UPLC BEH AMIDE column, under isocratic conditions within a 5 min run. Detection was achieved with a triple quadrupole MS applying electrospray ionization in positive mode. The method was fully validated and proved precise and accurate with in a linear range of 0.59-3.53 ng/ml in blood. The method was developed to provide insights on the level of exposure of infant population to phenylephrine after ocular administration.

Adenosine plasma levels and adenosine receptor levels determine the outcome of adenosine test and head-up tilt test in syncopal patients with a normal heart

Background/Introduction

The neurohumoral profile underlying the manifestation of reflex syncope remains incompletely understood. Adenosine plasma (ADP) and adenosine receptor (ADR) levels may differentiate the outcomes of head-up tilt table test (HUTT) and adenosine test (ADT) but their role in the diagnostic evaluation of patients with syncope has yet to be determined.

Purpose

We sought to assess the ADP and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences in the outcomes of the HUTT and ADT tests as well as to the ADP levels during HUTT.

Methods

HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole >6 seconds or heart block for >10 seconds after intravenous Adenosine 0.15 mg/kg administration in the supine position. ADP levels were assessed at three timepoints during the HUTT: at baseline (supine), immediately after bed tilt and, in cases of a positive HUTT, at the time of syncope. Patients were categorized in quintiles of very low, low, intermediate, high and very high baseline ADP levels. We also assessed the A2A ADR levels of monocytes.

Results

We prospectively analyzed 124 patients (71 women, age 46.78±21.01 years). ADT was positive in 12.9% of patients and HUTT in 44.4% of patients. Patients with very low baseline ADP levels (lowest quintile) more frequently presented with a positive ADT (odds ratio [OR] 4.08, 95% Confidence Interval [CI] 1.40 to 13.13, p<0.05). Baseline ADP did not differ between patients with positive and negative HUTT. However, patients with vasodepressor response to HUTT exhibited increase in ADP from baseline to bed tilt (0.33±1.03 vs. 0.42±1.14 ppm/Um/L, p<0.05) and in syncope (0.70±1.89, P<0.05), while no difference was noted in patients with cardioinhibitory or mixed response. Patients with positive ADT and negative HUTT had higher ADR levels (221.5±88.56 MFI) as compared to patients with negative ADT and positive HUTT (59.78±83.65 MFI, p<0.05) and to patients with positive ADT and HUTT (33.29±35.77 MFI, p<0.05). Within patients with positive HUTT, those with onset of syncope in the Isoprenaline provocation phase (>20 min) had lower ADR levels (80.88±238.98 vs 89.43±96.08 MFI, p<0.05).

Conclusion(s)

Baseline ADP levels are related to the outcome of ADT while an ADP increase immediately after bed tilt and in syncope is evident in vasodepressor response to HUTT. Higher ADR levels are related to positive ADT and negative HUTT. Lower ADR levels are associated with more delayed onset of syncope during HUTT. ADP and ADR levels warrant further investigation as they may characterize a subset of patients with specific responses to ADT and HUTT and may be implicated in the pathophysiology of reflex syncope.

Funding Acknowledgement

Type of funding sources: None.

Baseline adenosine plasma levels indicate differential response to adenosine test and head-up tilt test in syncopal patients

Background/Introduction

Head-up tilt table test (HUTT) and Adenosine test (ADT) can be useful in the diagnostic evaluation of syncope. Adenosine plasma (ADP) and Adenosine receptor (ADR) levels may differentiate the outcomes of HUTT and ADT but their precise role in the risk stratification of patients with syncope remains elusive.

Purpose

We sought to assess the ADP and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences in the outcomes of the HUTT and ADT tests as well as to the ADP levels during HUTT according to the baseline ADP levels.

Methods

HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole >6 seconds or heart block for >10 seconds after intravenous Adenosine 0.15 mg/kg administration in the supine position. ADP levels (ppm/Um/L) were assessed at three timepoints during the HUTT: at baseline (supine), immediately after bed tilt and, in cases of a positive HUTT, at the time of syncope. Patients were categorized in terciles of low, intermediate and high baseline ADP levels. We also assessed the A2A ADR levels of monocytes.

Results

We prospectively analyzed 106 patients (62 women, age 46.87±20.63 years). ADT was positive in 14.2% of patients and HUTT in 47.2% of patients. Females were more likely to have low ADP levels (odds ratio [OR] 2.70, 95% Confidence Interval [CI] 1.04 to 6.94, p<0.05). Patients with low baseline ADP levels showed a trend for positive ADT (OR 3.15, 95% CI 1.05 to 10.85, p=0.07), while patients with high baseline ADP levels showed a trend for negative HUTT (OR 2.35, 95% CI 0.94 to 5.90, p=0.075). Within patients with positive HUTT, those with low baseline ADP levels, showed an increase in ADP in the tilt phase (0.063 vs 0.027 ppm/Um/L, p<0.05) but not at the time of syncope (0.045 ppm/Um/L) while those with intermediate baseline ADP levels showed an increase in ADP in the tilt phase (0.16 vs 0.095 ppm/Um/L, p<0.05) which persisted during syncope (0.18 ppm/Um/L, p<0.05). Patients with high baseline ADP levels did not exhibit differences in ADP during positive HUTT. Higher baseline ADP levels were associated with smaller increases in the tilt phase (Pearson's r −0.621, p<0.001). ADR levels in patients with positive HUTT correlated positively with baseline ADP levels (Pearson's r 0.878, p<0.001).

Conclusion(s)

Baseline ADP levels may be related to the outcome of ADT and HUTT. ADP increases during HUTT except for patients with high baseline ADP. ADP and ADR levels warrant further investigation as they may characterize a subset of patients with specific responses to HUTT and may be implicated in the pathophysiology of reflex syncope.

Funding Acknowledgement

Type of funding source: None

P6573Adenosine plasma levels may determine tilt table test outcome in syncopal patients with prodromal symptoms

Background/Introduction

Head-up tilt table test (HUTT) and Adenosine test (ADT) are tools frequently used in the diagnostic workup of syncope. It has been suggested that patient responses to HUTT and ADT can be related to the plasma levels of Adenosine (ADPL) and Adenosine receptors (ADR). However, the exact type of association and the role of (ADPL) and ADR levels in the risk stratification and management of patients with syncope has not yet been clarified.

Purpose

We sought to assess the ADPL and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences with regards to the presence of a history of prodromal symptoms.

Methods

HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole >6 seconds or heart block for >10 seconds after intravenous Adenosine administration in a supine position at a dose of 0.15 mg/kg. ADPL were assessed at three timepoints during the HUTT: in the supine position, immediately after bed tilt and, in cases of a positive test, at the time of syncope. Furthermore, we assessed the A2A ADR of monocytes in the study patients.

Results

We prospectively analyzed 77 patients (48 women, age 47.05±21.10 years). ADT was positive in 16.7% of patients and HUTT in 49.4% of patients. ADPL in the supine position did not differ between patients with negative vs. positive ADT but showed a significant correlation with the body mass index (p=0.002). There was a trend for reduced ADPL at the tilt phase in patients with positive HUTT (0.32±0.89 vs. 0.42±0.77 ppm/Um/L, p=0.09). Of all patients, 60 (77.9%, 41 women, age 46.80±21.83 years) had reported a history of prodromal symptoms at syncope. In the subset of patients with prodromal symptoms, the ADL at the tilt phase were lower in patients with positive vs. negative HUTT (0.15±0.23 vs. 0.51±0.89, p<0.05). ADR did not differ among groups but showed a significant correlation with the ADL during syncope in patients with prodromal symptoms (p<0.05).

Conclusion(s)

Patients with prodromal symptoms and a positive HUTT demonstrate reduced ADPL at the tilt phase of HUTT preceding syncope. In these patients, ADPL in syncope correlate with the ADR. Adenosine plasma levels and receptors warrant further investigation and may predict the response to HUTT thereby contributing to the diagnostic evaluation and risk stratification of patients with syncope.

Metabolic profiling study of shikonin's cytotoxic activity in the Huh7 human hepatoma cell line

Shikonin and its enantiomer alkannin, which are natural products, have been extensively studied in vitro and in vivo for, among others, their antitumor activity. The investigation of the molecular pathways involved in their action is of interest, since they are not yet clearly defined. Metabolic profiling in cells can provide a picture of a cell's phenotype upon intervention, assisting in the elucidation of the mechanism of action. In this study, the cytotoxic effect of shikonin on a human hepatocarcinoma cell line was studied. Huh7 cells were treated with shikonin at 5 μM, and it was found that shikonin markedly inhibited cell growth. Metabolic profiling indicated alterations in the metabolic content of the cells and the culture media upon treatment, detecting the metabolic response of the cells. This study demonstrates the potential of metabolomics to improve knowledge on the mechanisms involved in shikonin's antitumor action.