Preterm labour detection by use of a biophysical marker: the uterine electrical activity

<p>Abstract</p> <p>Background</p> <p>The electrical activity of the uterine muscle is representative of uterine contractility. Its characterization may be used to detect a potential risk of preterm delivery in women, even at an early gestational stage.</p> <p>Methods</p> <p>We have investigated the effect of the recording electrode position on the spectral content of the signal by using a mathematical model of the women's abdomen. We have then compared the simulated results to actual recordings. On signals with noise reduced with a dedicated algorithm, we have characterized the main frequency components of the signal spectrum in order to compute parameters indicative of different situations: preterm contractions resulting nonetheless in term delivery (i.e. normal contractions) and preterm contractions leading to preterm delivery (i.e. high-risk contractions). A diagnosis system permitted us to discriminate between these different categories of contractions. As the position of the placenta seems to affect the frequency content of electrical activity, we have also investigated in monkeys, with internal electrodes attached on the uterus, the effect of the placenta on the spectral content of the electrical signals.</p> <p>Results</p> <p>In women, the best electrode position was the median vertical axis of the abdomen. The discrimination between high risk and normal contractions showed that it was possible to detect a risk of preterm labour as early as at the 27th week of pregnancy (Misclassification Rate range: 11–19.5%). Placental influence on electrical signals was evidenced in animal recordings, with higher energy content in high frequency bands, for signals recorded away from the placenta when compared to signals recorded above the placental insertion. However, we noticed, from pregnancy to labour, a similar evolution of the frequency content of the signal towards high frequencies, whatever the relative position of electrodes and placenta.</p> <p>Conclusion</p> <p>On human recordings, this study has proved that it is possible to detect, by non-invasive abdominal recordings, a risk of preterm birth as early as the 27th week of pregnancy. On animal signals, we have evidenced that the placenta exerts a local influence on the characteristics of the electrical activity of the uterus. However, these differences have a small influence on premature delivery risk diagnosis when using proper diagnosis tools.</p

Behavioral thermoregulation in mammals: a review

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Altérations au cours du vieillissement des capacités thermorégulatrices chez un primate non-humains, le Microcèbe (Microcebus murinus)

Age-related deteriorations in the effector mechanisms of thermoregulation may threaten the maintenance of homeostasis. This hypothesis was tested in a primate, the gray mouse lemur (Microcebus murinus), during thermal challenges. The season has emerged as a dominant parameter. During summer, aging did not impair normothermia and energy balance maintenance. However, age-related impairments were demonstrated in winter in response to low or high Ta. Indeed, daily Tc rhythms were widely depth during cold exposure and associated with negative energy balance. When exposed to heat, aged individuals exhibited reduced capacities to dissipate body. Age-related impairments in IGF-1 signalling have also been demonstrated. To conclude, aging was strongly associated in mouse lemurs with impaired control of Tc levels, with different levels according to season.La détérioration avec l'âge des mécanismes effecteurs de la thermorégulation pourrait menacer le maintien de l'homéostasie. Cette hypothèse a été testée chez un primate, le ivlicrocèbe (Microcebus murinus), lors de challenges thermiques. La saison est apparue comme un paramètre prédominant. En été, le vieillissement n'a pas perturbé le maintien de la normothermie et de la balance énergétique. En revanche, des difficultés liées à i'âge ont été démontrées en hiver en réponse à des Ta basses ou élevées. En effet, le rythme de température corporelle (Te) était largement approfondi au froid et associé à une perte de poids. Au chaud, une altération des capacités de dissipation de la chaleur corporelle a été mise en évidence. Des déficiences avec l'âge dans la signalisation à l'IGF-1 ont également pu être démontrées. Le vieillissement est donc fortement associé chez le Microcèbe au déclin des fonctions impliquées dans le contrôle de la Te, et ce de manière différentielle en fonction des saisons.PARIS5-BU Méd.Cochin (751142101) / SudocSudocFranceF

Automatic detection of mode mixing in empirical modal decomposition by non-stationarity detection : application to IMF of interest selection or denoising

La décomposition modale empirique est une méthode itérative permettant de décomposer un signal en différents modes ou IMF (Intrinsic Mode Function). Un algorithme de sélection des composantes modales d'intérêts a été récemment proposé. Cette méthode se base sur une étude statistique du bruit contenu dans chacune des IMF et sur un modèle mathématique de la répartition du bruit dans chacune des IMF, propre au signal analysé, par estimation du bruit sur le premier mode (qui est censé contenir uniquement du bruit). Cependant un phénomène de mixage de modes peut apparaître et aboutir à une surestimation du niveau de bruit dans le signal original. Certaines IMF seront donc considérées à tort comme du bruit. Nous proposons une méthode générale de détection du mixage de modes basée sur la détection de non stationnarité sur la première IMF. Une fois le mixage de modes identifié, nous proposons ensuite de corriger l'estimation du niveau de bruit contenu sur la première IMF par une extraction sur cette IMF de la partie signal et de la partie correspondant uniquement au bruit. Les résultats obtenus sur des signaux purement synthétiques ou issus de la mécanique et du génie biomédical montrent l'intérêt de l'approche proposée

Postural- and respiratory-related activities of abdominal muscles during post-exercise hyperventilation

International audienceThe present study focuses on the role of superficial abdominal muscles revealed by electromyographic recordings during the maintenance of a bipedal stance perturbed by post-exercise hyperventilation. Twelve healthy subjects performed six 30-second postural tests: one pre-exercise test while breathing quietly, then one test every minute for the five minutes immediately following a maximum-intensity, incremental cycling exercise test. Displacement of the centre of pressure in the sagittal plane was monitored over time. Myoelectric activities of the obliquus externus (OE), obliquus internus (OI) and rectus abdominis (RA) muscles were recorded by surface electromyography (EMG). Metabolic parameters were measured with a portable telemetric device. The change in ventilatory drive induced by exercise was accompanied by a significant increase in both postural sway parameters and EMG activities. For OE and OI, the increased EMG activities were prominent during expiration, whereas OI was silent during inspiration. OE and RA were activated during both expiration and inspiration. It is concluded that the compensation of respiratory disturbances of the erect posture appears to be less effective when minute ventilation increases. The patterns of muscle activity suggest that abdominal muscles are controlled differentially and that their functional coordination is dependent on the respiratory demand

Circadian rhythms of the spectral characteristics of uterine EMG: a case study

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Respiratory- and postural-related activities of abdominal muscles during post-exercise hyperventilation

International audienceAIM: The present study focused on the roles of the superficial abdominal muscles through electromyographic recordings during the maintenance of a bipedal stance perturbed by post-exercise hyperventilation. METHODS: Twelve healthy subjects had to perform six 30-second postural tests: one pre-exercise test while breathing gently and then one test every minute for the five minutes immediately following a maximum-intensity, incremental cycling exercise test. Subjects were asked to maintain an upright stance on a force plate for 30 s, with their eyes open. Movement of the centre of pressure in the sagittal plane was monitored in the time domain. Myoelectric activities of the rectus abdominis (RA), external oblique (OE) and internal oblique (OI) muscles were recorded unilaterally using surface electromyography (EMG). Ventilatory parameters were measured with a portable, telemetric device. RESULTS: The change in ventilatory drive induced by exercise was accompanied by a significant increase in both postural sway parameters and EMG activities. The quantification of EMG activities within the respiratory cycles revealed different EMG patterns. For OE and OI, the increased EMG activities were prominent during expiration. OI was silent during inspiration. OE and RA were activated during both expiration and inspiration. CONCLUSION: The results suggest that abdominal muscles play a role in regulating the ventilatory response to incremental cycling exercise test, although some of the observed activity may support postural adjustments, presumably to reduce respiratory disturbances

Gender markedly modulates behavioral thermoregulation in a non-human primate species, the mouse lemur (Microcebus murinus)

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Meal size and energy costs of digestion: insights from an omnivorous non-human primate (Microcebus murinus)

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Ajustement du budget énergétique à la contrainte alimentaire chez un primate frugivore (Microcebus murinus)

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