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Biomedical subjects

Curtis L Lowery

Publications and source records attributed to Curtis L Lowery.

At least 19 recordsLinked to original sources
PubMed2006

Fetal magnetoencephalography.

The assessment of the neurological integrity of the human fetus in utero is a technically challenging problem. New brain imaging devices can substantially improve our capabilities to describe functional brain activity in the fetus. It has been well established by fetal behavioral studies and investigations in preterm and term newborns that the brain is functional in utero. The major effort required to perform effective neurological functional investigations is designation of an integrated approach to neurological assessment and the generation of normative data. Currently, it is possible to record evoked brain activity elicited by auditory and visual stimulation from the fetus. In addition, there is growing evidence that spontaneous brain activity can be recorded in the fetus. This paper explores the current status of the brain-imaging field for fetal investigations and currently available data.

Brain↗
PubMed2006

Magnetoencephalography in healthy neonates.

OBJECTIVE: To describe magnetoencephalography (MEG) recordings in a cohort of healthy neonates. METHODS: We performed MEG and single channel EEG concomitantly in 21 healthy newborns. MEG and EEG signals were reviewed for gross comparison of general patterns and individual waveform characteristics. Spectral analysis was performed to quantify the signals. RESULTS: Our MEG recordings showed patterns comparable to classical neonatal EEG. Seventy-nine percent of the subjects exhibited the 'continuous polyfrequency activity' at some point in their recording. Sixty-three percent had the 'continuous slow' pattern, and 47% had the 'trace alternant' pattern. Spectral analysis revealed maximal power at frequencies of less than 4 Hz (delta band) in both MEG and EEG with a decline towards higher frequencies. CONCLUSIONS: Neonatal MEG is feasible and shares the basic EEG features and frequency content, with predominant activity in the slow frequency delta band. The latter corresponds to reports from earlier neonatal EEG studies. SIGNIFICANCE: MEG may prove to be useful in studies of neonatal brain functions.

Brain↗
PubMed2006

A two-period assessment of changes in specialist contact in a high-risk pregnancy telemedical program.

The purpose was to examine the organizational impact of a state-wide high-risk pregnancy telemedical system, Antenatal and Neonatal Guidelines, Education and Learning System (ANGELS), after the first year of its roll out. The focus is on several aspects of system organization, including the volume and diversity of patient-based telemedical consultations and weekly telemedical case discussions, telephone consultations, and changes in the pattern of birth-related patient transports. Individual data on patient transports and associated hospital days, provider-specialist telephone calls, and telemedical consultations were collected for two time periods: December 2002-May 2003 (prior to initiation of ANGELS), and December 2003-May 2004 (postinitiation of ANGELS). Different statistical tests were constructed to compare the two periods as appropriate. Significant increases were observed in the volume and geographic diversity of telemedical consultations and the volume of telephone consultations. There was a moderate, but nonsignificant decrease in the number of maternal transports to University of Arkansas School of Medical Sciences (UAMS), and the average length of stay decreased. The type of specialist-provider and specialist-patient contact has changed as the ANGELS high-risk pregnancy telemedical system has evolved over the first year. We conclude that the rollout of the ANGELS program is changing the shape of high-risk patient care in Arkansas, and we attribute that to an evolving collegial network between specialists and generalists.

Female↗
PubMed2006

Fetal and maternal magnetocardiography during flecainide therapy for supraventricular tachycardia.

BACKGROUND: Fetal magnetocardiography is a noninvasive technique capable of identifying fetal arrhythmias and can simultaneously characterize the cardiac rhythm of the mother and fetus. CASES: Three patients, two singleton pregnancies and one twin pregnancy, were admitted for evidence of fetal supraventricular tachycardia. Fetal magnetocardiography was used to monitor the effects of flecainide therapy on the fetus and mother. Two singleton pregnancy fetuses showed improved heart rate and cardiac rhythm within 1 week of the initial dosing. Maintenance dosages controlled the conditions thereafter. Flecainide slowed the supraventricular tachycardia in the twin subject, but magnetocardiography revealed maternal adverse effects necessitating termination of flecainide therapy. CONCLUSION: Magnetocardiography is a valuable tool for rhythm diagnosis and for monitoring the maternal and fetal cardiac rhythms in a patient undergoing flecainide therapy for fetal supraventricular tachycardia.

Anti-Arrhythmia Agents↗
PubMed2006

Equity in the development of telemedicine sites in an Arkansas high-risk pregnancy programme.

We investigated where telemedicine sites were placed in a telemedicine network to assist high-risk pregnancies in Arkansas. There were 14 telemedicine sites in 75 counties, excluding the central site in Pulaski county. Logistic regression was used to examine site placement. Five potential predictors of site placement were examined: (1) the logarithm of the number of births in the county (LOGBIRTHS); (2) an indicator of whether a county had an abnormal rate of low birthweight babies (HIGHLBW); (3) the proportion of the county population below the government's poverty level; (4) the ratio of black to white births; (5) an indicator of whether the county bordered the telemedicine hub site county. The results suggested that telemedicine sites were placed where there were more births (LOGBIRTHS, P = 0.001) and more low birthweight babies (HIGHLBW, P = 0.004). After controlling for these variables, the county poverty level did not reduce the likelihood of site placement. Thus telemedicine sites had been established in those areas where the need was great both in terms of immediate risk (rate of low birthweight babies) and in terms of the continuing pressure of large numbers of births. This is significant in view of the concentration of poor minorities in certain areas, which historically have not been matched by past distribution of resources.

Arkansas↗
PubMed2005

Fetal magnetoencephalography--a multimodal approach.

Past studies have shown the feasibility of recording fetal evoked responses to external stimuli using a non-invasive technique called magnetoencephalography (MEG). These studies were all performed using either auditory or visual stimuli and showed a fairly low detection rate for each modality, thus making this technology currently unreliable for fetal clinical applications. This study is based on the hypothesis that a multimodal approach of applying both auditory and visual stimulation paradigms in successive recording sessions could improve the probability of obtaining a fetal evoked response. A total of 34 studies were performed on 11 normal healthy fetuses at different stages of gestation starting as early as 28 weeks with a 151-channel fetal MEG system. The success rate of obtaining a response to either (or both) stimuli from a study at a given gestation age was 91%. All the 11 fetuses showed a response at least once over the gestation period the recordings were performed. A multimodal testing approach can improve the ability of the MEG technique to reliably monitor the functional development of the fetal brain.

Acoustic Stimulation↗
PubMed2005

Prolonged morphine exposure in utero causes fetal and placental vasoconstriction: a case report.

Vasoconstriction was observed in the fetal middle cerebral and umbilical arteries by Doppler assessment at 27 weeks gestation in a patient requiring continuous morphine infusion for pain control. Fetal heart tracings were also concerning. Fetal status improved after a change to fentanyl infusion, a shorter acting opioid. Caution is recommended when long-term chronic narcotic infusion is used in pregnancy.

Adult↗
PubMed2004

A simple wavelet-based test for evoked responses.

Statistically valid detection of evoked responses from magnetoencephalographic (MEG) sensors is complicated by temporal autocorrelation. By decorrelating time series and transforming them toward normality, the discrete wavelet transform (DWT) allows the analyst to test for an association between stimulus and sensor time series with appropriate degrees of freedom. Eswaran et al. (Neurosci. Lett. 2002a;331:128-32) used a 151-channel fetal MEG system to obtain serial recordings from 10 pregnant subjects. There were 3-8 recordings per subject. In each recording session, the fetus was stimulated by 500Hz and 1KHz tones with a relative frequency of 80-20%, respectively. In this new analysis of the same data, the fetal MEG signals were compared to two different stimulus waveforms: the frequent tone and the Novel stimulus, defined as a change in pitch. WaveDetect was developed to determine whether there was a significant association between the stimuli and the MEG traces. This test is performed by taking the DWT of each series and then computing the Spearman correlation between the wavelet coefficients for an appropriate scale. A significant response (i.e., correlated stimulus-sensor pair) was detected from each patient. This result suggests that the combination of serial recordings and WaveDetect may ensure reliable detection of auditory evoked responses.

Acoustic Stimulation↗
PubMed2004

Prediction of labor in term and preterm pregnancies using non-invasive magnetomyographic recordings of uterine contractions.

OBJECTIVE: The purpose of this study was to characterize the noninvasive magnetic field recordings of the uterine electrophysiological activity in patients reporting onset of uterine contractions. STUDY DESIGN: Transabdominal magnetomyographic (MMG) recordings were performed with the use of the SARA system's 151 primary magnetic sensors (CTF Systems Inc, Coquitlam, British Columbia, Canada). Eleven term and 4 preterm patients participated in the study. On all patients, cervical dilation and outcomes were recorded. RESULTS: Of 8 patients having a peak MMG activity exceeding 8 pT (pico Tesla), all but 1 delivered within 48 hours of our recordings. Of the 7 patients with peak activity below 8 pT, 5 failed to deliver within 48 hours of the recordings. This observation reflects an increase in the electrophysiologic activity of the myometrium as labor progresses. CONCLUSION: MMG evaluation provides a new noninvasive method for the prediction of labor. Further studies are in progress to determine the temporal relationship of MMG changes with the onset of labor.

Adult↗
PubMed2004

Functional development of the visual system in human fetus using magnetoencephalography.

The development of the human brain in utero is normally regarded as a dynamic process involving mainly structural and quantitative changes in neurons and their distribution. However, it is generally accepted that a parallel development of functional specialization occurs in certain areas of the brain, especially in the primary cortex. Nearly all knowledge of functional fetal brain development has been obtained from various animal studies rather than human studies. These studies show that the primary sensory areas like auditory, visual, and somatosensory cortex show a basic function similar to that of a fully developed brain. It has been specifically shown that the visual system develops during fetal life and becomes functional before birth. Several studies have demonstrated the feasibility of using visual evoked response (VER) recordings on preterm human infants to follow the functional development of the visual system. With the advent of the noninvasive technique of magnetoencephalography (MEG), human fetal VER recordings are now possible thus providing the opportunity to track its functional development with gestation. We present and discuss the results of VER recordings in human fetuses starting at 28 weeks of gestation performed using a 151-channel MEG system.

Evoked Potentials, Visual↗
PubMed2004

Fetal magnetoencephalography: current progress and trends.

Multimodal testing is the key to successful fetal neurological assessment. New mutichannel SQUID (Superconducting Quantum Interference Device) sensor devices can now be used to effectively record fetal auditory evoked responses (fAER) and visual evoked responses (VER), spontaneous brain activity, and heart activity. In this paper, we review the current progress in the area of fetal magnetoencephalography (fMEG) and also present an overview of the studies performed using a system called SARA that is specifically designed for fetal MEG studies. With the capability of recording spontaneous and evoked magnetic fields, we believe the monitoring of the neurological status of the fetus can be effectively implemented and can encourage the development of new strategies of intervention for the high-risk fetus.

Brain↗
PubMed2004

Fetal MEG redistribution by projection operators.

The fetal magnetoencephalogram (fMEG) is measured in the presence of large interference from the maternal and fetal magnetocardiograms. This interference can be efficiently attenuated by orthogonal projection of the corresponding spatial vectors. However, the projection operators redistribute the fMEG signal among sensors. Although redistribution can be readily accounted for in the forward solution, visual interpretation of the fMEG signal topography is made difficult. We have devised a general, model-independent method for correction of the redistribution effect that utilizes the assumption that we know in which channels the fMEG should be negligible (such channels are distant from the known fetal head position). In a simplified case where the fMEG can be explained by equivalent current dipoles, the correction can also be obtained from fitting the dipoles to the fMEG signal. The corrected fMEG signal topography then corresponds to the dipole forward solution, but without orthogonal projection. We illustrate the redistribution correction on an example of experimentally measured flash evoked fMEG.

Algorithms↗
PubMed2003

Infection, replication, and cytopathology of human papillomavirus type 31 in trophoblasts.

Human papillomavirus (HPV) DNA is preferentially found in spontaneous abortions, specifically residing in trophoblasts, and transfected HPV-16 DNA replicates and produces progeny in 3A trophoblasts in culture. In this study 3A trophoblasts were shown to display both HPV receptors and infection by HPV-31b and HPV-6 virus resulted in de novo (increasing) HPV DNA replication in these cells (inhibited by neutralizing anti-HPV31b antibodies). Reverse transcription-polymerase chain reaction analysis revealed that E1;E4, E6, and L1 were significantly expressed at days 5 (early) and 10 (late), respectively, and in situ immunocytochemistry verified L1 protein expression. Perhaps most important, HPV 31b virus infection caused both a decrease in 3A trophoblast cell numbers in a dose-dependent manner and a low trophoblast-endometrial cell adhesion (both inhibited by neutralizing anti-HPV-31 antibodies). These data further support the hypothesis that HPVs are fully active in trophoblasts and may cause some spontaneous abortions.

Cell Adhesion↗
PubMed2003

Noninvasive antepartum recording of fetal S-T segment with a newly developed 151-channel magnetic sensor system.

OBJECTIVE: The objective of this study was to evaluate the efficiency of the detection of the S-T segment in the fetal PQRST complex that is recorded in the antepartum period with the use of a newly developed noninvasive 151-channel magnetic sensor array. STUDY DESIGN: One hundred two fetal magnetocardiographic recordings were performed on normal fetuses with gestational ages that ranged from 27.5 to 39.5 weeks. After the removal of the interfering maternal heart signals, the fetal heart data were inspected to detect the presence of P, QRS, and T segments. RESULTS: The QRS complex was detectable in 100%, the P wave was detectable in 95.1%, and the T wave was detectable in 87.3% of the recordings. CONCLUSION: Fetal magnetocardiography was recorded successfully, the QRS complex was observed in all subjects, and the T detection rate increased, with the gestational age reaching a peak of 97%. Further study of the S-T segment through the antepartum period could lead to advances in the detection of fetal jeopardy before labor.

Cardiotocography↗
PubMed2002

Short-term serial magnetoencephalography recordings offetal auditory evoked responses.

The study objective was to determine whether short-term serial magnetoencephalographic (MEG) measurements would increase the odds in favor of obtaining fetal auditory evoked responses in normal fetuses. The recordings were performed in two phases using the newly developed 151-channel fetal MEG system, superconducting quantum interference device array for reproductive assessment. Ten pregnant subjects with gestational ages ranging from 30-35 weeks were recruited to participate. Daily recordings were performed over a minimum of 3 days during 1 week of gestation and repeated in the same subjects between 36 and 40 weeks gestation. In 80% of subjects, auditory evoked responses were detected at least once. In healthy fetuses, serial recordings over a short span of time increased the rate of detecting fetal evoked response.

Evoked Potentials, Auditory↗