Empirical mode decomposition applied for non-invasive electrohysterograhic signals denoising.

The electrical activity of the uterus, i.e. the electrohysterogram (EHG), is one of the most prominent tool for preterm labour. There is no standard acquisition set up and often the EHG is corrupted with different types of noise: maternal and fetal electrocardiogram (mECG, fECG), electrical activity of the skeletal muscles, movement artifacts, power line interference (PLI) etc. Moreover, some of these noises overlap in frequency domain with the EHG. Thus, simple linear filtering approaches are not adequate. In this paper the empirical mode decomposition (EMD), a simple and data driven method, is proposed for EHG denoising. The method is evaluated on simulated data having different signal to noise ratios (SNRs) obtaining promising results.

Fetal ECG extraction from abdominal signals: a review on suppression of fundamental power line interference component and its harmonics.

Interference of power line (PLI) (fundamental frequency and its harmonics) is usually present in biopotential measurements. Despite all countermeasures, the PLI still corrupts physiological signals, for example, electromyograms (EMG), electroencephalograms (EEG), and electrocardiograms (ECG). When analyzing the fetal ECG (fECG) recorded on the maternal abdomen, the PLI represents a particular strong noise component, being sometimes 10 times greater than the fECG signal, and thus impairing the extraction of any useful information regarding the fetal health state. Many signal processing methods for cancelling the PLI from biopotentials are available in the literature. In this review study, six different principles are analyzed and discussed, and their performance is evaluated on simulated data (three different scenarios), based on five quantitative performance indices.

Fetal electrocardiogram enhancement in abdominal recordings: recording setup analysis.

The fetal electrocardiogram (fECG) obtained from the abdominal signals, to monitor the wellbeing of the fetus, is a weak signal, recorded by placing electrodes on the maternal abdomen surface. When recording the abdominal fECG, the main problem is to separate the fECG from the background noise, including the maternal electrocardiogram (mECG) and/or the power line interference (PLI), this leading to an improved fECG signal to noise ratio (SNR). This paper proposes and evaluates three types of recording configurations, having different reference location, and analyzes the performance of each recording setup, based on the corresponding SNRs, quantitatively evaluated. The fECG extraction is carried out in order to evaluate the performance of each proposed configuration.

Monitoring the fetal heart rate variations by means of time-variant multivariate analysis.

The analysis of the fetal heart rate (fHR) is important in detecting the fetal distress related with hypoxic episodes, noticed sometimes during the uterine activity, which can severely affect the fetus. Occasional synchrony between the fHR and the maternal heart rate (mHR) was reported and the mHR shows some variations during pregnancy and labor, especially when the contractions are very strong. The current study proposes a new strategy to investigate the relations between the fHR, the mHR and the uterine activity, by applying the time-variant Partial Directed Coherence (tvPDC).

Isolation method and xeno-free culture conditions influence multipotent differentiation capacity of human Wharton's jelly-derived mesenchymal stem cells.

INTRODUCTION: Human Wharton's jelly (WJ) has become a preferred source of mesenchymal stem cells (MSCs) whose clinical applications are limited by the use of adequate xeno-free (XF), in vitro manipulation conditions. Therefore, the objective of our study was to characterize WJ-derived MSCs (WJ-MSCs), isolated by different methods and cultured in a commercially available, MSC XF medium, not least of all by investigating their endothelial differentiation capacity. METHODS: WJ explants and enzymatically dissociated WJ cells were cultured in a defined, XF medium for MSCs. Adherent cells at passages 2 and 5 were characterized as MSCs by flow cytometry, MTT, real-time quantitative reverse transcription PCR, and functional multipotent differentiation assays. The endothelial differentiation capacity of MSCs isolated and expanded until passage 2 in the MSC XF medium, and then subcultured for five passages in a commercially available endothelial growth medium (group A), was assessed over serial passages, as compared to adherent WJ-derived cells isolated and expanded for five consecutive passages in the endothelial medium (group B). RESULTS: The MSC phenotype of WJ explant- and pellet-derived cells, isolated and expanded in the MSC XF medium, was proven based on the expression of CD44/CD73/CD90/CD105 surface markers and osteo-/adipo-/chondrogenic multipotent differentiation potential, which differed according to the isolation method and/or passage number. Upon exposure to endothelial differentiation cues, cells belonging to group A did not exhibit endothelial cell characteristics over serial passages; by contrast, WJ pellet-derived cells belonging to group B expressed endothelial characteristics at gene, protein and functional levels, potentially due to culture conditions favoring the isolation of other stem/progenitor cell types than MSCs, able to give rise to an endothelial progeny. CONCLUSIONS: The use of defined, MSC XF media for isolation and expansion of human WJ-MSCs is a prerequisite for the establishment of their real endothelial differentiation capacity, as candidates for clinical therapy applications. Thus, the standardization of WJ-MSCs isolation and culture expansion techniques in defined, MSC XF media, for their accurate characterization, would be a priority in the stem cell research field.

Morphological and functional adaptation of the maternal heart during pregnancy.

BACKGROUND: Pregnancy provides a unique model to study the adaptation of the heart in a physiological situation of transient load changes. The aim of this study was to assess the performance of the left ventricle (LV) in normal, uncomplicated pregnancies while considering the actual LV load and shape. METHODS AND RESULTS: Serial echocardiographic examinations were performed in 51 women in each pregnancy trimester and 3 to 6 months after delivery. Data from 10 nulliparous, age-matched women were used as the control. Conventional parameters of LV function (ejection fraction) as well as myocardial deformation (strain) were interpreted, taking into consideration maternal hemodynamics and LV shape. Cardiac output increased during pregnancy because of a higher stroke volume in early pregnancy and a late increase in heart rate, whereas total vascular resistance decreased. Progressive development of eccentric hypertrophy was observed, which subsequently recovered postpartum. Sphericity index decreased from the first to the third trimester (1.92±0.17 versus 1.71±0.17) and returned postpartum to values comparable to the control. Although higher LV stroke work was noted toward the third trimester (5.9±1.1 versus 5.3±1.0 Newton meter, P<0.001), ejection fraction showed no significant changes. LV strain decreased significantly in late pregnancy (-19.5±2% to -17.6±1.6%, P<0.001) and returned to baseline values after delivery (-19.5±2%). CONCLUSIONS: Pregnancy is a physiological process associated with increased cardiac performance and progressive LV remodeling. These changes are not directly reflected by parameters traditionally considered to describe systolic function, such as ejection fraction and longitudinal deformation. While ejection fraction was insensitive to the functional changes, the transient decrease in longitudinal deformation becomes only plausible when considering the changes in LV geometry.

Chromogranin A as serum marker of pituitary adenomas.

OBJECTIVE: The diagnostic impact of chromogranin A (CgA) measurement has been studied in various neuroendocrine tumours (NET) such as pheochromocytomas, gastrinomas and neuroblastomas. Clinically nonfunctioning pituitary adenomas (NFPA) are generally diagnosed on tumoural symptoms or hypopituitarism and, except for gonadotrophins and their free subunits which may be increased in the case of gonadotrophinomas, markers of endocrine secretory activity are lacking not only for diagnostic purpose but also in the postoperative follow-up of these patients. As the presence of CgA has been demonstrated by immunohistochemistry in pituitary adenomas, we performed this study to further assess the sensitivity of CgA measurement in sporadic pituitary adenomas using a new, specific, sandwich immunoassay. SUBJECTS: We first completed a basal normative data set obtained using this assay by studying four healthy men (49 +/- 13 years old), five healthy premenopausal women (35.8 +/- 7.5 years old) and five healthy postmenopausal women (49.1 +/- 4.6 years old) basally and after TRH administration. Twenty-seven patients [12 men (64.2 +/- 11.8 years), even premenopausal women (38.4 +/- 5.7 years) and eight postmenopausal women (67.7 +/- 10.3 years)] with NFPA, 15 acromegalic patients [nine men (45 +/- 13.3 years), six women (52 +/- 14.9 years)] and 19 patients with a prolactin-secreting adenoma [four men (41.2 +/- 18 years) and 15 women (31.2 +/- 7.5 years), with a macroadenoma (n = 11) or a microadenoma (n = 8)] had basal and TRH-stimulated measurement of CgA. A gonadotrophin-releasing hormone (GnRH)-stimulation test was also performed in two, four and four patients, respectively. All patients had sporadic pituitary adenomas. MEASUREMENTS: Serum CgA was measured using a solid-phase two-site immunoradiometric assay based on monoclonal antibodies that bind to two distinct contiguous epitopes within the 145-245 region of CgA. RESULTS: Mean basal CgA concentration in 14 normal subjects was 80.2 ng/ml (SD: 31.7; range 19-124). A cut-off value for normal range was thus set at 125 ng/ml. TRH injection did not change significantly the CgA levels, peak values remaining less than 124 ng/ml. Three out of 27 subjects with NFPA (11%) had elevated basal CgA levels (576, 143, 241 ng/ml, respectively). Serum levels of CgA were not influenced by TRH in any of the NFPA subjects (including those three with increased basal levels). One out of 15 acromegalic patients (6.6%) and one out of 19 hyperprolactinemic patients (5.2%) had elevated serum basal CgA which did not significantly increase after TRH administration. In the remaining patients TRH-tests did not modify CgA levels. GnRH administration did not modify CgA levels. CONCLUSIONS: CgA serum levels measurement, assessed with a novel assay, does not provide a helpful marker for the clinical management of functioning and NFPA.