6 research outputs found
Evaluation of Innotrac Aio! Second-Generation Cardiac Troponin I Assay: The Main Characteristics for Routine Clinical Use
The availability of a simple, sensitive, and rapid test using whole blood to facilitate processing and to
reduce the turnaround time could improve the management of patients presenting with
chest pain. The aim of this study was an evaluation of the Innotrac Aio! second-generation
cardiac troponin I (cTnI) assay. The Innotrac Aio! second-generation cTnI assay was
compared with the Abbott AxSYM first-generation cTnI, Beckman Access AccuTnI, and Innotrac
Aio! first-generation cTnI assays. We studied serum samples from 15 patients with positive
rheumatoid factor but with no indication of myocardial infarction (MI). Additionally, the stability
of the sample with different matrices and the influence of hemodialysis on the cTnI
concentration were evaluated. Within-assay CVs were 3.2%–10.9%, and
between-assay precision ranged from 4.0% to 17.2% for cTnI. The functional sensitivity
(CV = 20 %) and the concentration giving CV of 10% were approximated to be 0.02 and 0.04,
respectively. The assay was found to be linear within the tested range of 0.063–111.6
μ g/L. The correlations between the second-generation Innotrac Aio!, Access,
and AxSYM cTnI assays were good (r coefficients 0.947–0.966), but
involved differences in the measured
concentrations, and the biases were highest with cTnI at low concentrations. The
second-generation Innotrac Aio! cTnI assay was found to be superior to the first-generation assay
with regard to precision in the low concentration range. The stability of the cTnI level was best in the
serum, lithium-heparin plasma, and lithium-heparin whole blood samples (n = 10 , decrease
< 10 % in 24 hours at +20°C and at +4°C.
There was no remarkable influence of hemodialysis on the cTnI release. False-positive
cTnI values occurred in the presence of very high rheumatoid factor values, that is, over 3000 U/L.
The 99th percentile of the apparently healthy reference group was ≤ 0.03
μ g/L. The results demonstrate the very good analytical performance of the second-generation
Innotrac Aio! cTnI assay
Effect of extreme data loss on long-range correlated and anti-correlated signals quantified by detrended fluctuation analysis
We investigate how extreme loss of data affects the scaling behavior of
long-range power-law correlated and anti-correlated signals applying the DFA
method. We introduce a segmentation approach to generate surrogate signals by
randomly removing data segments from stationary signals with different types of
correlations. These surrogate signals are characterized by: (i) the DFA scaling
exponent of the original correlated signal, (ii) the percentage of
the data removed, (iii) the average length of the removed (or remaining)
data segments, and (iv) the functional form of the distribution of the length
of the removed (or remaining) data segments. We find that the {\it global}
scaling exponent of positively correlated signals remains practically unchanged
even for extreme data loss of up to 90%. In contrast, the global scaling of
anti-correlated signals changes to uncorrelated behavior even when a very small
fraction of the data is lost. These observations are confirmed on the examples
of human gait and commodity price fluctuations. We systematically study the
{\it local} scaling behavior of signals with missing data to reveal deviations
across scales. We find that for anti-correlated signals even 10% of data loss
leads to deviations in the local scaling at large scales from the original
anti-correlated towards uncorrelated behavior. In contrast, positively
correlated signals show no observable changes in the local scaling for up to
65% of data loss, while for larger percentage, the local scaling shows
overestimated regions (with higher local exponent) at small scales, followed by
underestimated regions (with lower local exponent) at large scales. Finally, we
investigate how the scaling is affected by the statistics of the remaining data
segments in comparison to the removed segments