A Wearable System for In-Home and Long-Term Assessment of Fetal Movement

Objectives: This paper presents a novel wearable system for in-home and long-term fetal movement monitoring on a reliable and easily accessible basis.Material and methods: The system mainly consists of four accelerometers for fetal movement signal acquisition, a microcontroller for signal processing and an Android-based device interacting with the microcontroller via Bluetooth Low Energy (BLE), providing the mother with information related to the fetal movement in an intelligible way.Results: The proposed system can deliver reliable results with a specificity of 0.99 and a sensitivity of 0.77 for fetal movement time series signal classification.Conclusion: The proposed wearable system will provide a good alternative to optimize the use of medical professionals and hospital resources, and has potential applications in the field of e-Health home care. Besides, the fetal movement acceleration signals acquired with volunteers (pregnant women) help establish an initial database for future medical analysis of sensor-recorded fetal behaviors.     

Detection and Processing Techniques of FECG Signal for Fetal Monitoring

Fetal electrocardiogram (FECG) signal contains potentially precise information that could assist clinicians in making more appropriate and timely decisions during labor. The ultimate reason for the interest in FECG signal analysis is in clinical diagnosis and biomedical applications. The extraction and detection of the FECG signal from composite abdominal signals with powerful and advance methodologies are becoming very important requirements in fetal monitoring. The purpose of this review paper is to illustrate the various methodologies and developed algorithms on FECG signal detection and analysis to provide efficient and effective ways of understanding the FECG signal and its nature for fetal monitoring. A comparative study has been carried out to show the performance and accuracy of various methods of FECG signal analysis for fetal monitoring. Finally, this paper further focused some of the hardware implementations using electrical signals for monitoring the fetal heart rate. This paper opens up a passage for researchers, physicians, and end users to advocate an excellent understanding of FECG signal and its analysis procedures for fetal heart rate monitoring system.     

Current and emerging techniques of fetal cell separation from maternal blood

Intense research has been carried out in recent years into methods that aim to harvest fetal genetic material from maternal blood as substitutes to amniocentesis and chorionic villus sampling. Just over 30 years have past since the first fetal cells were separated from maternal blood using flow cytometry highlighting the prospect of non-invasive prenatal diagnosis of fetal abnormalities. The aim of this review paper is to describe the most commonly used cell separation methods with emphasis on the isolation of fetal cells from maternal blood. The most significant breakthroughs and advances in fetal cell separation are reviewed and critically analyzed. Although much has been accomplished using well established techniques, a rapid and inexpensive method to separate fetal cells with great accuracy, sensitivity and efficiency to maximize cell yield is still required. In the past decade MEMS (Micro Electro Mechanical Systems) technologies have enabled the miniaturization of many biological and medical laboratory processes. Lab-on-chip systems have been developed and encompass many modules capable of processing different biological samples. Such chips contain various integrated components such as separation channels, micropumps, mixers, reaction and detection chambers. This article will also explore new emerging MEMS based separation strategies, which hope to overcome the current limitations in fetal cell separation.     

Analysis of fetal breathing in real time using a microprocessor

A system has been designed using an inexpensive microprocessor to analyze fetal breathing movements on a breath-by-breath basis in real time. An algorithm was developed which would recognize fetal breathing from the changes in tracheal pressure and which was capable of rejecting the artifactual changes caused by fetal or maternal movements. The tracheal pressure signal was digitized (at 51 samples/s), differentiated, and the start and peak of each breath was recognized from the zero-crossing points of the differentiated signal. Each breath was validated for size and shape according to a set of criteria incorporated into the breath recognition algorithm. On acceptance of the pressure change as a valid breath, the inspiratory time, breath amplitude, breath-to-breath interval, and inspiratory effort were calculated and stored in memory. The program was structured so that the microprocessor was able to accept new data and output summarizes of previous data concurrently. More than 95% of breaths in records contaminated with movement artifacts were recognized.     

Myoelectric signal processing for control of powered limb prostheses

Progress in myoelectric control technology has over the years been incremental, due in part to the alternating focus of the R&D between control methodology and device hardware. The technology has over the past 50 years or so moved from single muscle control of a single prosthesis function to muscle group activity control of multifunction prostheses. Central to these changes have been developments in the means of extracting information from the myoelectric signal. This paper gives an overview of the myoelectric signal processing challenge, a brief look at the challenge from an historical perspective, the state-of-the-art in myoelectric signal processing for prosthesis control, and an indication of where this field is heading. The paper demonstrates that considerable progress has been made in providing clients with useful and reliable myoelectric communication channels, and that exciting work and developments are on the horizon.     

Online control of evaluation algorithms of the image applied to identification of deglutition function]

Comprehensive software and hardware have been developed for the processing of biosignals. Such automatic signal processing, however not only has advantages, but also drawbacks. The question as to the reliability of the evaluation algorithm arises when the signal is modified, in the presence of interindividual differences, and in particular when noise is superimposed. This is of great interest for long-term recording when the original signal can no longer be inspected visually. The aim of our work was to display the signals on the screen of a monitor simultaneously with lines marking the points (start, end, extreme value, etc.) processed by the specific signal processing algorithm. The program package permits the on-line recording and monitoring of signals, the parallel processing and marking of detected events on the monitor, as well as storage of the parameters extracted. It is a very effective tool for developing, improving and monitoring of algorithms and their efficiency for signal processing.     

Detection of the fetal ECG during labour by an intrauterine probe

The feasibility of detecting the fetal ECG (FECG) from within the uterus in labour by a technique which is non-invasive to the fetus, has been investigated. The design of a special multi-electrode flexible probe has demonstrated that the FECG can be obtained with signal amplitudes of 20–300 μV and a success rate similar to that of the scalp electrode. Under favourable conditions very large signals can be detected in utero compared to a scalp electrode, but average signal amplitudes are lower. The probe is suitable as a carrier for other sensors such as pressure and temperature transducers. Currently, simultaneous FECG and intrauterine pressure measurement using a commercially available transducer within the same probe has been achieved.     

PrlC, a suppressor of signal sequence mutations in Escherichia coli, can direct the insertion of the signal sequence into the membrane

The prlC gene product of Escherichia coli can be altered by mutation so that it restores export of proteins with defective signal sequences. The strongest suppressor, prlC8, restores processing of a mutant signal sequence to a rate indistinguishable from the wild-type. Data obtained by changing gene dosage of the dominant suppressor and its specificity for different signal sequence mutations suggest that PrlC8 interacts directly with the hydrophobic core of the signal sequence. Despite the fact that signal sequence processing appears to be mediated by leader peptidase, the processed mature protein is not translocated efficiently from the cytoplasm. Results obtained with various double mutants indicate that PrlC8-mediated processing of mutant signal sequences does not require components of the cellular export machinery such as SecA, SecB or PrlA (SecY) and that the block in translocation from the cytoplasm occurs because PrlA (SecY) fails to recognize the defective signal sequence. We suggest that PrlC8 directs insertion of the mutant signal sequence into the membrane bilayer to an extent that processing by leader peptidase can occur. This reaction is novel in that it has not been observed previously in vivo.     

Development of a neuronal pressure sensor

Neuronal sensory systems are capable of performing very complex signal processing functions. Reconstruction of such sensory systems in vitro should enable whole-cell biological sensors to be generated that possess inherent signal processing capabilities. In this paper, the results of preliminary investigations to produce a mechanosensory neuronal network are presented. An in vitro network of rat dorsal root ganglion neurons has been produced on a microelectrode plate revealing an interesting rhythmical pattern of spontaneous discharges. This periodic activity has been shown to be disrupted following the application of a static pressure to the cell culture. These results indicate that neuronal networks represent a practical system that may be used for the development of intelligent, whole-cell, biological sensors.     

Human fetuses have nonlinear cardiac dynamics.

Approximate entropy (ApEn) is a statistic that quantifies regularity in time series data, and this parameter has several features that make it attractive for analyzing physiological systems. In this study, ApEn was used to detect nonlinearities in the heart rate (HR) patterns of 12 low-risk human fetuses between 38 and 40 wk of gestation. The fetal cardiac electrical signal was sampled at a rate of 1,024 Hz by using Ag-AgCl electrodes positioned across the mother's abdomen, and fetal R waves were extracted by using adaptive signal processing techniques. To test for nonlinearity, ApEn for the original HR time series was compared with ApEn for three dynamic models: temporally uncorrelated noise, linearly correlated noise, and linearly correlated noise with nonlinear distortion. Each model had the same mean and SD in HR as the original time series, and one model also preserved the Fourier power spectrum. We estimated that noise accounted for 17.2-44.5% of the total between-fetus variance in ApEn. Nevertheless, ApEn for the original time series data still differed significantly from ApEn for the three dynamic models for both group comparisons and individual fetuses. We concluded that the HR time series, in low-risk human fetuses, could not be modeled as temporally uncorrelated noise, linearly correlated noise, or static filtering of linearly correlated noise.     

Design and synthesis of a consensus signal sequence that inhibits protein translocation into rough microsomal vesicles.

Most signal sequences are found to vary considerably in length and primary sequence, but possess some common structural features. Analysis of known signal sequences has led to the design of a 19-residue sequence that, although not a naturally occurring signal, possesses the structural features that commonly occur in pre-proteins. This peptide has been synthesized by solid-phase methods, and has been shown to inhibit, in a concentration-dependent manner, the processing in vitro of nascent pre-prolactin, pre-forms of pancreatic digestive enzymes, and pre-placental lactogen. The peptide acts at the cytoplasmic surface of microsomal vesicles added to the protein translation system, preventing translocation of the nascent chains to the lumenal space of vesicles where signal peptidase normally cleaves to remove the signal from nascent pre-proteins.     

小波变换与生物医学信号处理

作为数字信号处理领域的一个重要分支,生物医学信号处理理论与技术的研究一直受到国内外科技工作者的高度重视。小波变换是近年来发展起来的一种新的信号分析工具。本文结合生物医学信号与小波变换的特点,探讨了小波变换在生物医学信号处理领域的应用前景。     

Targeted point mutation that creates a unique Eco RI site within the signal codons of the beta-lactamase gene without altering enzyme secretion or processing

A method has been developed for constructing site-specific mutations by using a strongly selectable marker on which to "piggy-back" a desired mutation that may be phenotypically silent. Using this approach, a new unique Eco RI restriction site has been generated at the beginning of the signal codons of the beta-lactamase gene of the plasmid pBR322. The consequential alteration of the second amino acid of the signal from Ser to Arg has no effect on either the transport or the processing of the beta-lactamase.     

The consequences of stepwise deletions from the signal-processing site of beta-lactamase

Amino acids have been deleted from the processing site of pre-beta-lactamase, either into the signal sequence or into the mature protein. Whereas the loss of more than 2 amino acid residues from the C-terminal end of the signal sequence prevents the translocation of the protein into the periplasm, the removal of two or more amino acids from the beginning of the mature protein has no effect on the translocation of the truncated protein. The insertion of an additional one to three amino acids at the processing site has no detectable phenotypic consequence either. It appears that many sequences for the first few residues of the mature protein allow successful translocation and processing. In sharp contrast, the removal of one (but not both) of the amino acids that flank the processing site results in a severe growth defect in the host cell and very low expression of the protein. Yet removal of two amino acids from either side of the processing site, or removal of both the flanking residues of the processing site, results in normal secretion and signal cleavage. These results illustrate the limits on the amino acid sequence around the processing junction and suggest that interference with the signal cleavage step can lead not only to aborted secretion but also to pleiotropic consequences for the growth of the host organism.     

Cloning of a maltogenic alpha-amylase from Bacillus stearothermophilus

Abstract We have cloned and expressed a novel maltogenic alpha-amylase from B. stearothermophilus on plasmid in B. subtilis . Originally the plasmid was very unstable in the absence of selection, but was stabilized due to a spontaneous, copy number reducing mutation. The promoter region and the extension of the gene have been analysed, and a provisional DNA sequence has been determined. The N-terminal of the mature amylase has been determined and shown to be in accordance with signal peptidase processing after a typical Gram-positive signal sequence of 33 amino acids.     

Regulation of the hypothalamic-pituitary-adrenal axis in birth

In sheep an increase in fetal pituitary-adrenal function, reflected in rising concentrations of plasma ACTH and cortisol, is important in relation to fetal organ maturation and the onset of parturition. This review presents evidence that implicates the hypothalamic-pituitary-adrenal axis in the control of parturition and describes recent experiments that explore in detail the maturation of the fetal hypothalamus and pituitary in relation to fetal adrenal function. Recent improvements for the measurement of ACTH in unextracted plasma and the ability to maintain vascular catheters in chronically catheterized fetal sheep have enabled subtle changes in fetal ACTH concentrations to be detected. As a result of these advances it has now been established that the terminal rise in cortisol, which is responsible for the onset of parturition in sheep, is preceded by an increase in fetal plasma ACTH concentrations. This has led to the hypothesis that birth results from the sequential development of the fetal hypothalamic-pituitary-adrenal axis with the signal originating from the fetal brain. This increase in trophic drive to the fetal adrenal may result from changes in the responsiveness of the fetal pituitary gland to factors that stimulate the release of ACTH. Corticotropin releasing factor (CRF) and arginine vasopressin are two such factors that stimulate the secretion of ACTH and cortisol secretion in the chronically catheterized fetal sheep. The response to these factors increases with gestational age and is sensitive to glucocorticoid feedback. Furthermore, repeated administration of CRF to immature fetal sheep results in pituitary and adrenal activation and in some cases may lead to premature parturition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of the presence of amniotic fluid for optical transabdominal fetal monitoring using Monte Carlo simulations

About a third of babies are delivered by Cesarean section. There has been an increase in maternal deaths during labor due to complications with subsequent births after a C-section. Therefore, there is a clinical motivation to reduce the C-section rate. Current techniques are, however, inefficient at determining fetal distress leading to a high false positive rate for complications and ultimately a C-section. For the current study, Monte Carlo simulations were used to calculate the amount of signal received on a model of a pregnant mother, as well as, the percent of the signal that comes from the fetal layer. Models with and without a 1 mm amniotic fluid were compared and showed differing trends.