P-542 Accuracy of Rapid Prenatal Testing by 24-chromosome analysis using Next Generation Sequencing

Study question

What is the accuracy of NGS versus QF-PCR in the Rapid Prenatal Testing?

Summary answer

NGS seems to be a reliable alternative for Rapid Prenatal Testing and expand the aneuploidy screening to all 24 chromosomes.

What is known already

As part of the prenatal care, whenever an invasive testing is needed, rapid prenatal analysis is performed to rule out the most common aneuploidies (i.e., trisomy for chromosomes 13, 18 and 21), using FISH or QF-PCR. Some studies describe the use of the NGS as an alternative to detect genetic alterations in the DNA from amniocytes or chorionic villus sampling (CVS) in Prenatal Genetic Testing.

Study design, size, duration

This research study evaluates the accuracy of NGS analysis for Rapid Prenatal Testing comparing the results with gold standard techniques. A total of 32 amniotic fluid samples clinically analysed by karyotype (n = 3) or QF-PCR (n = 29) were used as reference resulting in: normal male (n = 3); normal female (n = 9); trisomy 13 (n = 3); trisomy 18 (n = 5; one by karyotype); trisomy 21 (n = 10; one by karyotype); partial trisomy 3q26q26/partial monosomy 5p13p15.33 (n = 1; by karyotype); and triploid XXY (n = 1).

Participants/materials, setting, methods

All 32 samples were analysed using an NGS platform validated for PGT-A (Preimplantation Genetic Testing for aneuploidy). Ion ReproSeq™ PGS kit was used for library preparation, Ion Chef™ and Ion S5 System instruments for sequencing and Ion Reporter software for data analysis (Thermo Fisher Scientific, USA), with a proprietary bioinformatics pipeline (v2.0) for the analysis of 24-chromosome aneuploidies and partial duplication/deletions (≥10Mb). NGS results were compared with the reference QF-PCR/Karyotype results for accuracy evaluation.

Main results and the role of chance

When comparing NGS versus QF-PCR/Karyotype results, we observed a 100% concordance for the detection of trisomy 13 (3 out of 3 samples), trisomy 18 (5 out of 5 samples), trisomy 21 (10 out of 10 sample) and partial trisomy 3q/partial monosomy 5p (1 out of 1 sample). We did not identify false positives for any of the chromosomes in which comparison could be done as they were analysed in the reference samples (chromosomes 13, 18, 21, X and Y for QF-PCR reference samples, and all 24 chromosomes for Karyotype reference samples). In one of the samples, the triploid XXY, the NGS profile for the sex chromosomes was compatible either with a normal male result with maternal cell contamination or with a triploid XXY result, and was finally classified as non-informative for NGS.

Limitations, reasons for caution

The NGS cannot identify deletions/duplications <10Mb and mosaicism <30%. The platform used cannot identify some types of polyploidies, therefore, additional analysis (Short Tandem Repeats, karyotype, or SNP-arrays) when normal results are needed. However, improvements in technology that are currently underway will solve this limitation.

Wider implications of the findings

Based on the experience gained since the implantation of the NGS method for the characterization of the chromosomal status of DNA samples, the use of the NGS platform and protocols for the rapid prenatal test samples has as benefit to expand the screening analysis to all 24 chromosomes.

Trial registration number

Not applicable

Metabolic and hormonal responses to body carbohydrate store depletion followed by high or low carbohydrate meal in sedentary and physically active subjects

The study was designed to determine metabolic and hormonal responses to acute modification of body carbohydrate stores by exercise and subsequent meals and to find out whether the responses depend on the training status of subjects. Nine sedentary students and 10 endurance athletes took part in four experimental sessions. During control session, after overnight fast oxygen uptake and CO2 production were measured and blood glucose, free fatty acids (FFA), insulin (I), leptin (L), growth hormone (GH), testosterone (T), catecholamines, ACTH and cortisol were determined. The remaining sessions were preceded by 1.5 h exercise at 70% HRmax in the evening followed by 12-16 hrs fast till morning when subjects ate either high-carbohydrate (H-CHO) or low-carbohydrate (L-CHO) meal or fasted. Respiratory gases and blood samples were collected before and 2 hours after meal. In glycogen depleted subjects respiratory quotient (RQ), I, norepinephrine (NE) and L decreased, whilst other variables were unaltered. Changes in I and NE were greater in athletes than in sedentary subjects. After H-CHO RQ, blood glucose, I and NE increased and FFA, GH and T decreased. The latter effect was greater in athletes than in untrained subjects. After L-CHO, RQ was at the fasting level and FFA increased only in sedentary group. In both groups I increased and GH and T decreased. Neither meal affected L concentration. In conclusion, hormonal and metabolic changes observed after depleting carbohydrate stores resemble those occurring during starvation. Composition of the ingested meal affects postprandial metabolism, which additionally depends on the subjects' training status.

Influence of body carbohydrate store modification on catecholamine and lactate responses to graded exercise in sedentary and physically active subjects

Aim of this study was to elucidate the influence of carbohydrate store modification on exercise capacity and catecholamine thresholds. Nine sedentary students and 10 endurance athletes volunteered for the study consisting of four sessions in one-week intervals. During control session (C) subjects performed graded exercise till exhaustion with workload increasing by 50 Watts every 3 min after an overnight fast. Blood lactate and catecholamines were determined at rest, after each workload and at exhaustion. In the evening preceding each of the remaining three sessions subjects performed glycogen reducing exercise lasting 1.5 hrs at 70% HRmax. Till next morning they did not eat any meal but drank water. Two hours before exercise subjects were given either a high-carbohydrate (H-CHO) or a low-carbohydrate (L-CHO) meal of approx. 1000 kcal or remained fasted (F). Depletion of carbohydrate stores enhanced contribution of fat-derived energy substrates at submaximal workloads, but did not influence either maximal oxygen consumption, workload and lactate concentration or lactate threshold. Low carbohydrate availability resulted in elevated concentration of catecholamines only in untrained subjects. Ingestion of a meal either high or low in carbohydrates diminished those changes. Catecholamine thresholds were similar in all sessions and higher in athletes' group.

Effect of adrenergic blockade on plasma adrenomedullin concentration during static handgrip in patients with heart failure

Our previous study showed that static handgrip caused increases in the plasma adrenomedullin (ADM) both in patients with heart failure (HF) and healthy subjects. The present study was designed to determine the role of the sympathetic nervous system in mediating plasma ADM changes during handgrip in patients with HF. Twelve male HF patients (II class NYHA) treated with carvedilol, a non-selective adrenergic blocker (TC) and 12 patients untreated with carvedilol (UC) performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand. At the end of both exercise bouts and in 5 min of the recovery period, plasma ADM and catecholamines were determined. In addition, heart rate, blood pressure and stroke volume (SV) were measured. The baseline plasma ADM, noradrenaline (NA) and adrenaline (A) levels were similar in the two groups of patients, while SV was higher (P<0.05) in TC than in UC. During exercise plasma ADM concentrations were lower (P<0.05) in TC than in UC, but the handgrip-induced increases in plasma ADM did not differ between the groups. Plasma ADM correlated with NA concentrations (r = 0.764) and with SV (r = -0.435) and increases in plasma ADM expressed as percentage of baseline values correlated with those of plasma NA (r = 0.499), diastolic BP (r = 0.550) and total peripheral resistance (r = 0.435). The study suggests that the sympathetic nervous system may be involved in the stimulation of ADM secretion during static exercise either directly or by changes in the haemodynamic response.

Effect of prolonged dynamic exercise on plasma adrenomedullin concentration in healthy young men

The aim of the study was to find out whether prolonged exercise influences plasma adrenomedullin (ADM) concentration and whether it is related to the hormonal, metabolic and cardiovascular changes. Eighteen healthy subjects (age 25+/-1 yrs) were submitted to cycle exercise for 90 min at 70% of maximal oxygen uptake. Heart rate (HR) and blood pressure (BP) were measured continously. Before, at 30(th) min, and at the end of exercise venous blood samples were taken for [ADM], noradrenaline [NA], adrenaline [A], atrial natriuretic peptide [ANP], plasma renin activity PRA, interleukin-6 [IL-6] and lactate [LA] determination. Significant increases in plasma ADM and IL-6 were found at 90(th) min whereas other hormones were elevated already at 30(th) min of exercise. Positive correlations were ascertained between [ADM] and [NA] (r=0.47), [ANP] (r=0.35) or [IL-6] (r=0.35) and between exercise-induced increases in [ADM] and [NA] (r=0.38). PRA correlated positively with [NA] and [ANP]. Negative correlation was found between plasma [ADM] and diastolic BP. The present data suggest that increase in sympathetic nervous activity and cytokine induction during prolonged exercise may be involved in plasma ADM release and that increase in ADM and ANP secretion may be a compensatory mechanism against further elevation of blood pressure.

Cardiovascular and neurohormonal responses to lower body negative pressure (LBNP): effect of training and 3 day bed rest

Both intensive training and bed confinement impair orthostatic tolerance, however, moderate training may exert beneficial effect on cardiovascular adjustment to gravitational stimuli. It was hypothesized that moderate training attenuates effects of bed rest. To test this assumption 24 healthy male volunteers aged 20.8+/-0.9 yrs were subjected to 6 degrees head down bed rest (HDBR) for 3 days before and after 6 weeks of moderate endurance training. Before and after HDBR graded LBNP tests (-15, -30, -50 mmHg) were performed. During these tests heart rate (HR), stroke volume (SV), blood pressure (BP), plasma catecholamines, ACTH, adrenomedullin, atrial natriuretic peptide, plasma renin activity (PRA) and hematocrit were determined. HDBR did not systematically influence LBNP tolerance up to -50 mmHg, but it enhanced rates of reduction of SV, cardiac output and systolic BP and increased elevations of HR and PRA. Training did not alter significantly effects of HDBR on LBNP-induced changes in HR, SV, CO and TPR but it attenuated decrease in systolic BP and diminished increases in plasma noradrenaline and PRA. In conclusion, training has negligible effect on the HDBR-induced changes in central hemodynamics during LBNP but may increase vascular sensitivity to some vasoconstricting factors.

Effect of 6-week endurance training on hemodynamic and neurohormonal responses to lower body negative pressure (LBNP) in healthy young men

Endurance training is considered as a factor impairing orthostatic tolerance although an improvement and lack of effect have been also reported. The mechanisms of the changes and their relation to initial tolerance of orthostasis are not clear. In the present study, effect of moderate running training on hemodynamic and neurohormonal changes during LBNP, a laboratory test simulating orthostasis, was investigated in subjects with high (HT) and low (LT) tolerance of LBNP. Twenty four male, healthy subjects were submitted to graded LBNP (-15, -30 and -50 mmHg) before and after training. During each test heart rate (HR), stroke volume (SV) and blood pressure, plasma catecholamines, ACTH, adrenomedullin, atrial natriuretic peptide, and renin activity were determined. Basing on initial test, 13 subjects who withstood LBNP at -50 mmHg for 10 min were allocated into HT group and 11 subjects who earlier showed presyncopal symptoms to LT group. Training improved LBNP tolerance in six LT subjects. This was associated with attenuated rate of HR increase and SV decline (before training, at -30 mmHg deltaHR was 21 +/- 4 beats/min and deltaSV - -36+/- 8 ml while after training the respective values were 8 +/- 4 beats/min and -11+/- 6 ml). No differences in hemodynamic response were found in HT subjects and those from LT group whose LBNP tolerance was unchanged. In neither group training affected neurohormonal changes except inhibition of plasma ACTH rise in subjects with improvement of LBNP tolerance. It is concluded that some subjects with low orthostatic tolerance may benefit from moderate training due to improvement of cardiac function regulation.

Hemodynamic and neuroendocrine predictors of lower body negative pressure (LBNP) intolerance in healthy young men

Exposure to LBNP results in body fluid shift to lower extremities similarly as under influence of orthostatic stress. In susceptible persons it leads to syncope. For better understanding why certain individuals are more susceptible to orthostatic challenges it seemed necessary to collect more data on hemodynamic and neuroendocrine adjustments occurring before onset of presyncopal symptoms Accordingly, in this study heart rate (HR), blood pressure (BP), stroke volume (SV), cardiac output (CO), hematocrit, plasma catecholamines, adrenomedullin, ACTH and plasma renin activity (PRA) were measured in 24 healthy men during graded LBNP (-15, -30 and -50 mmHg). Thirteen subjects completed the test (HT group) whereas 11 had presyncope signs or symptoms at -30 mmHg or at the beginning of -50 mmHg (LT group). Comparison of these groups showed that LT subjects had lower baseline total peripheral resistance and higher plasma adrenomedullin. During LBNP plasma catecholamine and PRA increases were even greater in LT than in HT group while plasma adrenomedullin elevations were similar in both groups. Plasma ACTH increased only in LT group following presyncope symptoms. Low tolerant group showed more rapid decline of SV and CO than HT subjects from the beginning of LBNP. It is suggested that measurements of SV at the level of LBNP which did not evoke any adverse symptoms may be of predictive value for lower orthostatic tolerance.

Exercise training and 3-day head down bed rest deconditioning: exercise thermoregulation

Bed rest (BR) deconditioning causes excessive increase of exercise core body tempera-ture, while aerobic training improves exercise thermoregulation. The study was designed to determine whether 3 days of 6 degrees head-down bed rest (HDBR) affects body temperature and sweating dynamics during exercise and, if so, whether endurance training before HDBR modifies these responses. Twelve healthy men (20.7+/-0.9 yrs, VO2max: 46+/-4 ml x kg(-1) x min(-1) ) underwent HDBR twice: before and after 6 weeks of endurance training. Before and after HDBR, the subjects performed 45 min sitting cycle exercise at the same workload equal to 60% of VO2max determined before training. During exercise the VO2, HR, tympanic (Ttymp) and skin (Tsk) temperatures were recorded; sweating dynamics was assayed from a ventilated capsule on chest. Training increased VO2max by 12.1% (p<0.001). Resting Ttymp increased only after first HDBR (by 0.22 +/- 0.08 degrees C, p<0.05), while exercise equilibrium levels of Ttymp were increased (p<0.05) by 0.21 +/- 0.07 and 0.26 +/- 0.08 degrees C after first and second HDBR, respectively. Exercise mean Tsk tended to be lower after both HDBR periods. Total sweat loss and time-course of sweating responses were similar in all exercise tests. The sweating threshold related to Ttymp was elevated (p<0.05) only after first HDBR.

IN CONCLUSION

six-week training regimen prevents HDBR-induced elevation of core temperature (Ttymp) at rest but not during ex-ercise. The post-HDBR increases of Ttymp without changes in sweating rate and the tendency for lower Tsk suggest an early (<3d) influence of BR on skin blood flow.

Plasma adrenomedullin response to maximal exercise in healthy subjects

The aim of the study was to find out whether maximal exercise performed by healthy young men influences plasma adrenomedullin concentration (ADM) and is the peptide level related to the cardiovascular, metabolic and hormonal changes induced by exercise. Ten subjects (age 24+/-1.0 yr) participated in the study. They performed graded bicycle ergometer exercise until exhaustion. Heart rate (HR) and blood pressure (BP) were measured throughout the test. Before and at the end of exercise venous blood samples were taken for [ADM], noradrenaline [NA], adrenaline [A], growth hormone [hGH], cortisol and lactate [LA] determination. Plasma [ADM] decreased during exercise from 1.71+/-0.09 to 1.53+/-0.10 pmol x l(-1) (p<0.01). This was accompanied by increases in plasma catecholamines and [hGH], while plasma cortisol level did not change. Positive correlation was found between the exercise-induced decreases in plasma ADM and diastolic BP. Blood [LA], systolic and mean BP at the end of exercise correlated negatively with plasma [ADM]. No significant interrelationships were found between plasma ADM, catecholamines or the other hormones measured. The present data suggests, that maximal exercise inhibits ADM secretion in young healthy men. Metabolic acidosis and a decrease in peripheral resistance might be involved in this effect.

[Concentration of serum vitamin C in workers exposed to selected physical and chemical risk factors]

Determination of the serum vitamin C levels may yield the information on the nutritional status of workers. Increasing community awareness of the health-enhancing nutrition patterns as an element of the promotion of lifestyles conducive to health among workers may limit a negative impact of risk factors on workers' health. The aim of this study was to analyse the levels of serum vitamin C in workers exposed to selected physical (noise, electromagnetic fields) and chemical risk factors present in the work environment. Two randomised groups of male workers, one exposed to physical factors (n = 43; mean age 39.5 +/- 8.6 yr.), and the other to chemical factors (n = 40; mean age 38.3 +/- 8.0 yr.) were included in the study. The control group was composed of male workers (n = 36; mean age 40.4 +/- 10.1 yr.) exposed neither to physical nor to chemical factors. In all subjects, the serum vitamin C levels were measured using the spectrophotometric method by Kyaw. The mean serum vitamin C levels in the workers exposed to physical and chemical factors were 30.1 (mumol/l) and 30.9 (mumol/l), respectively, and their statistical significance was lower (p < 0.01) as compared with the mean serum vitamin C levels of 39.7 (mumol/l) in the control group.

[Analysis of occupational accidents in the years 1982-1994 in the Szczecin Province]

The aim of the study was to analyse the incidence of accidents at work in the Szczecin voivodship in 1982-94. In the analysis the number of workers employed in the national economy and the number of accidents were taken into account. The rate of accidents at work (the number of accidents/1,000 workers in /1000), the accident severity (the number of work disability days/the number of accidents at work), the rate of fatal accidents at work (the number of fatal accidents/1,000 workers in /1000), the rate of acute injuries (the number of severe injuries per 1,000 accidents at work) were determined. The rates of accidents at work and fatal accidents in the Szczecin voivodship were compared with the rates in the whole country during the same period. The number of workers employed throughout the period between 1982-94 maintained at almost the same level. It increased mostly in 1990 and then decreased (Table 1). The largest number of accidents was registered in 1983 and the lowest in 1994. During the period studied the number of fatal accidents and absenteeism due to accidents at work decreased, however, the rates of fatal accidents and acute injuries increased. The rate of accidents at work in the Szczecin voivodship during the years 1982-94 was higher than in the whole country.

Assessment of the nasal mucosa in workers exposed to the prolonged effect of phosphorite and apatite dusts

One hundred and thirty one workers occupationally exposed to phosphorite and apatite dusts and a control group underwent repeated laryngological and cytological examinations of nasal mucosa smears. The clinical examination showed chronic simple or atrophic rhinitis. The cytological test revealed metaplasia of the respiratory epithelium towards squamous epithelium in all smears. Both the rate of catarrhal changes and the degree of epithelial metaplasia varied with the duration of exposure.