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Biomedical subjects

P Peirano

Publications and source records attributed to P Peirano.

At least 19 recordsLinked to original sources
PubMed2002

Polysomnographic pattern recognition for automated classification of sleep-waking states in infants.

A robust, automated pattern recognition system for polysomnography data targeted to the sleep-waking state and stage identification is presented. Five patterns were searched for: slow-delta and theta wave predominance in the background electro-encephalogram (EEG) activity; presence of sleep spindles in the EEG; presence of rapid eye movements in an electro-oculogram; and presence of muscle tone in an electromyogram. The performance of the automated system was measured indirectly by evaluating sleep staging, based on the experts' accepted methodology, to relate the detected patterns in infants over four months of post-term age. The set of sleep-waking classes included wakefulness, REM sleep and non-REM sleep stages I, II, and III-IV. Several noise and artifact rejection methods were implemented, including filters, fuzzy quality indices, windows of variable sizes and detectors of limb movements and wakefulness. Eleven polysomnographic recordings of healthy infants were studied. The ages of the subjects ranged from 6 to 13 months old. Six recordings counting 2665 epochs were included in the training set. Results on a test set (2,369 epochs from five recordings) show an overall agreement of 87.7% (kappa 0.840) between the automated system and the human expert. These results show significant improvements compared with previous work.

Algorithms↗
PubMed2002

Spontaneous motor activity in human infants with iron-deficiency anemia.

This study compared spontaneous motor activity in 6-month-old Chilean infants with or without iron-deficiency anemia (IDA) who were otherwise healthy. Activity was assessed in conjunction with polysomnographic recording during an afternoon nap in 11 infants with IDA and 15 with normal hemoglobin levels. All infants were given oral iron, and activity was reassessed at 12 and 18 months. Using actigraphs placed on the ankle, the frequency of movement units per minute was determined for each waking/sleep state. The total amount of time infants were in an alert-active state before and after the nap was used to calculate the proportion of movements/minute of waking. There were no differences between anemic and nonanemic infants in total recording time, duration of sleep, or motor activity during sleep. However, infants with IDA showed reduced motor activity during waking at all ages. The magnitude of the differences increased at 12 and 18 months. Thus, IDA was associated with reduced motor activity in infants even after iron treatment. It will be important to confirm these results in a larger sample and to determine the 24-h pattern of motor activity, since reduced motor activity may limit infants' opportunities to explore and learn from the social and physical environment.

Anemia, Iron-Deficiency↗
PubMed2002

Twenty-four-hour motor activity in human infants with and without iron deficiency anemia.

Iron deficiency anemia (IDA) is a very common nutritional problem that alters motor activity. The aim of this study was to compare 24-h motor activity in the home in healthy 6-month-old infants with and without IDA. Activity was assessed via actigraphs on the leg during 24 continuous hours in 17 Chilean infants with IDA and 18 with normal hemoglobin levels. All infants were given oral iron, and activity was reassessed at 12 and 18 months. The frequency of movement units per minute was determined for each waking/sleep state during the day and night, and the duration of each state was computed. At 6 months of age, there were no differences between anemic and nonanemic infants in time per state. However, infants with IDA showed an overall increase in motor activity compared to controls. These differences were no longer observed at 12 and 18 months of age. Increased activity during the period of IDA raises the issue of a shared underlying mechanism with restless legs syndrome, a sensorimotor dysfunction where iron deficiency increases the severity of the symptoms and iron supplementation ameliorates them. Due to previous findings of decreased motor activity in the laboratory at 12 months during the waking time surrounding an afternoon nap, we also compared those data to a nap in the home. Infants with IDA were less active in the laboratory than in the home. The home versus laboratory results suggest that contextual factors affect the motor activity of IDA infants to a larger extent than controls.

Anemia, Iron-Deficiency↗
PubMed2001

Essential fatty acids in visual and brain development.

Essential fatty acids are structural components of all tissues and are indispensable for cell membrane synthesis; the brain, retina and other neural tissues are particularly rich in long-chain polyunsaturated fatty acids (LC-PUFA). These fatty acids serve as specific precursors for eicosanoids, which regulate numerous cell and organ functions. Recent human studies support the essential nature of n-3 fatty acids in addition to the well-established role of n-6 essential fatty acids in humans, particularly in early life. The main findings are that light sensitivity of retinal rod photoreceptors is significantly reduced in newborns with n-3 fatty acid deficiency, and that docosahexaenoic acid (DHA) significantly enhances visual acuity maturation and cognitive functions. DHA is a conditionally essential nutrient for adequate neurodevelopment in humans. Comprehensive clinical studies have shown that dietary supplementation with marine oil or single-cell oil sources of LC-PUFA results in increased blood levels of DHA and arachidonic acid, as well as an associated improvement in visual function in formula-fed infants matching that of human breast-fed infants. The effect is mediated not only by the known effects on membrane biophysical properties, neurotransmitter content, and the corresponding electrophysiological correlates but also by a modulating gene expression of the developing retina and brain. Intracellular fatty acids or their metabolites regulate transcriptional activation of gene expression during adipocyte differentiation and retinal and nervous system development. Regulation of gene expression by LC-PUFA occurs at the transcriptional level and may be mediated by nuclear transcription factors activated by fatty acids. These nuclear receptors are part of the family of steroid hormone receptors. DHA also has significant effects on photoreceptor membranes and neurotransmitters involved in the signal transduction process; rhodopsin activation, rod and cone development, neuronal dendritic connectivity, and functional maturation of the central nervous system.

Brain↗
PubMed2001

Resumption of ovarian function during lactational amenorrhoea in breastfeeding women with polycystic ovarian syndrome: endocrine aspects.

BACKGROUND: The aim of this study was to evaluate the changes in gonadotrophin concentrations and the dynamics of the episodic fluctuations of circulating LH during night-time, in fully breastfeeding normal women and in those with polycystic ovarian syndrome (PCOS) during lactational amenorrhoea and after weaning, in order to provide insights into the onset of this syndrome. Additionally, ovarian activity was evaluated by ultrasound examination and steroid concentrations. METHODS: Twelve lactating PCOS (LPCOS) women and six normal lactating (NL) women of similar age were selected. On the 4th and 8th week postpartum (PP) and eight weeks after weaning, blood samples were collected every 10 min (10.00--20.00h). Gonadotrophin concentrations were determined in all samples. Steroid hormones were measured in one fasting sample and ovarian morphology was assessed by ultrasound. RESULTS: On the 8th week PP, LH pulse frequency was higher and FSH concentrations were lower in LPCOS women compared with NL women, and steroid hormone concentrations remained low, except for androstenedione which was higher in LPCOS patients. After weaning, similar differences were observed between both groups. PCOS patients also showed enlarged ovaries with a PCOS pattern in the three study periods. CONCLUSIONS: The enlarged ovaries associated with higher androstenedione concentrations suggest that PCOS is a primary ovarian defect, making it difficult to establish if the abnormal LH pattern observed in these women is primary or secondary to the ovarian dysfunction.

Adult↗
PubMed1999

Expert-system classification of sleep/waking states in infants.

This work is part of a project to develop an expert system for automated classification of the sleep/waking states in human infants; i.e. active or rapid-eye-movement sleep (REM), quiet or non-REM sleep (NREM), including its four stages, indeterminate sleep (IS) and wakefulness (WA). A model to identify these states, introducing an objective formalisation in terms of the state variables characterising the recorded patterns, is presented. The following digitally recorded physiological events are taken into account to classify the sleep/waking states: predominant background activity and the existence of sleep spindles in the electro-encephalogram; existence of rapid eye movements in the electro-oculogram; and chin muscle tone in the electromyogram. Methods to detect several of these parameters are described. An expert system based on artificial ganglionar lattices is used to classify the sleep/waking states, on an off-line minute-by-minute basis. Algorithms to detect patterns automatically and an expert system to recognise sleep/waking states are introduced, and several adjustments and tests using various real patients are carried out. Results show an overall performance of 96.4% agreement with the expert on validation data without artefacts, and 84.9% agreement on validation data with artefacts. Moreover, results show a significant improvement in the classification agreement due to the application of the expert system, and a discussion is carried out to justify the difficulties of matching the expert's criteria for the interpretation of characterising patterns.

Electroencephalography↗
PubMed1999

The effect of sleep state on electroretinographic (ERG) activity during early human development.

To assess the effects of sleep state on human retinal electric responses, full-field electroretinograms were obtained in a cross-sectional study from 123 preterm infants at 36, 40 and 56 weeks of post-gestational age. At each age, electroretinographic recordings were assigned to one of two groups according to whether the infants were in active sleep or quiet sleep. Both sleep states were determined behaviorally. Pure rod, maximal, 30 Hz flicker and light adapted single cone responses were evaluated when a sleep state was clearly established. Peak-to-peak amplitudes of most electroretinographic responses were significantly larger in active sleep relative to quiet sleep at 36 and 40 weeks of post-gestational age. We speculate that larger amplitudes during active sleep may play a role in the maturation of the visual system.

Age Factors↗
PubMed1998

Evidence of altered central nervous system development in infants with iron deficiency anemia at 6 mo: delayed maturation of auditory brainstem responses.

Iron deficiency anemia has long been thought to have effects on the central nervous system (CNS). Finding direct evidence of this in human infants, however, has been challenging. Auditory brainstem responses (ABRs) provide a noninvasive means of examining an aspect of the CNS that is rapidly maturing during the age period when iron deficiency is most common. ABRs represent the progressive activation of the auditory pathway from the acoustic nerve (wave I) to the lateral lemniscus (wave V). The central conduction time (CCT, or wave I-V interpeak latency) is considered an index of CNS development because myelination of nerve fibers and maturation of synaptic relays lead to an exponential reduction in the CCT from birth to 24 mo. In 55 otherwise healthy, 6-mo-old Chilean infants (29 with iron deficiency anemia and 26 nonanemic control infants), the CCT was longer in those who had been anemic at 6 mo, with differences becoming more pronounced at 12- and 18-mo follow-ups despite effective iron therapy. The pattern of results--differences in latencies but not amplitudes, more effects on the late ABR components (waves III and V), and longer CCTs (as an overall measure of nerve conduction velocity)--suggested altered myelination as a promising explanation, consistent with recent laboratory work documenting iron's essential role in myelin formation and maintenance. This study shows that iron deficiency anemia in 6-mo-old infants is associated with adverse effects on at least one aspect of CNS development and suggests the fruitfulness of studying other processes that are rapidly myelinating during the first 2 y of life.

Anemia, Iron-Deficiency↗
PubMed1996

Role of essential fatty acids in the function of the developing nervous system.

The basis for n-3 fatty acid essentially in humans includes not only biochemical evidence but functional measures associated with n-3 deficiency in human and nonhuman primates. Functional development of the retina and the occipital cortex are affected by alpha-linolenic acid deficiency and by a lack of docosahexaenoic acid (DHA) in preterm infant formulas and, as reported more recently, in term diets. Functional effects of n-3 supply on sleep-wake cycles and heart rate rhythms support the need for dietary n-3 fatty acids during early development. Our results indicate that n-3 long-chain polyunsaturated fatty acids should be considered provisionally essential for infant nutrition. DHA may also be required by individuals with inherited metabolic defects in elongation and desaturation activity, such as patients with peroxisomal disorders and some forms of retinitis pigmentosa.

Animals↗
PubMed1996

Respiratory characteristics during sleep in healthy small-for- gestational age newborns.

OBJECTIVE: Small-for-gestational age (SGA) infants born with intrauterine growth retardation (IUGR) differ from appropriate-for-gestational age (AGA) infants by: a) alterations in a number of neurologic and neurophysiologic characteristics; b) modified heart rate variability during the neonatal period; and c) increased morbidity rates during the first months of life. However, there are no data on the impact of IUGR on respiratory function at birth. METHODS: We studied newborns who were 35 to 36, 37 to 38, and 39 to 41 weeks' conceptional age (CA): 31 were AGA and 26 were SGA. All were clinically and neurologically normal at birth and none exhibited abnormal events during the first year of life. Polygraphic recordings were performed between two meals during the normal postnatal stay in the maternity ward. RESULTS: During both active sleep (AS) and quiet sleep (QS), SGA infants in all CA groups had significantly higher values for the incidence of 2 to 4.9 seconds and 5 to 9.9 seconds central respiratory pauses (RP), the apnea index (AI) [AI=% of nonbreathing time], and the time spent with periodic breathing (PB), as compared with AGA infants. Respiratory frequency was usually similar in SGA and AGA infants. In addition, the trend of age-related respiratory modifications was disturbed in SGA infants, as compared with AGA infants: at 39 to 41 weeks CA, SGA infants had no significant decreases in RP, AI, or PB, and no increase in respiratory frequency. However, between-state differences were similar in both groups. In all AGA and SGA infant groups respiratory frequency seemed to be an individual characteristic: infants who breathed faster during AS breathed faster during QS, and vice-versa. CONCLUSION: Our data demonstrate significant modifications in the establishment of respiratory rhythm control in SGA infants, whereas the patterns of state-related and subject-dependent breathing characteristics were similar in SGA and AGA infants. We speculate that the dysregulation of respiratory function control maturation observed in healthy SGA infants may be related to subtle brainstem modifications attributable to the decreased blood supply and chronic hypoxia associated with IUGR.

Apnea↗
PubMed1995

Dynamics of EEG background activity level within quiet sleep in successive cycles in infants.

We investigated in infants the emergence of the trends of the EEG synchronization throughout quiet sleep (QS) as a function of the QS rank. The night sleep of 3 groups with 6 subjects each (aged respectively 9-18 weeks, 21-47 weeks, and 16-45 years) was recorded. A parameter value reflecting the degree of synchronization of the EEG background activity for successive epochs was computed by automatic analysis. For each QS phase 3 indicators of the dynamics of the time course of the EEG parameter activity were determined: the range (difference between the EEG parameter value at the beginning of the QS episode and that at the trough), the trough latency (after QS onset), and the rate of synchronization (range/trough latency). The range and the trough latency increased with age, whereas the rate of synchronization decreased. The range and the rate of synchronization decreased in the successive cycles, whereas the trough latency increased. These results provide further support for the hypothesis of the early emergence of the process S mechanisms and suggest that the framework of the 2-process model could account also for the development of both the EEG background activity dynamics and the sleep-wake organization.

Adolescent↗
PubMed1995

Modulation of motor activity patterns and sleep states in low-risk prematurely born infants reaching normal term: a comparison with full-term newborns.

To evaluate the influence of prematurity and postnatal age on the relationship between motor activity (MA) and sleep states, forty clinically and neurologically normal infants were recorded polygraphically and grouped according to their gestational (GA, prematures: < 36 weeks, full-term: 37-41 weeks) and conceptional (CA, 37-38 and 39-41 weeks) ages. Sleep states (active: AS, and quiet: QS) were defined by the concordance of EEG and rapid eye movement criteria. Movements of both upper (UL) and lower (LL) limbs were independently recorded. In all groups the amount of MA in both UL and LL clearly predominated in AS compared with QS (p < 0.02). Contrariwise, both the longest period without movement and the no-movement 20-sec epochs were significantly higher in QS than in AS (p < 0.005). In AS, age-related modifications and modulation of MA amount throughout the state were similar for PRT and FT groups: a) in both groups a significant decrease of MA with advancing CA was observed (p < 0.05); b) MA throughout the state was randomly distributed regardless of CA. In QS, however, PRT were distinguishable from FT by the absence of: a) a significant decrease of MA amount with advancing CA, together with a reduced increase of both the longest period without movements and the no-movement 20-sec epochs; b) prevalence of MA in LL compared with UL; c) modulation of the distribution of MA throughout the state.

Anthropometry↗
PubMed1994

Heart rate and sleep states in infants.

Heart Rate (HR) was analyzed during the first six Quiet Sleep (QS)--Paradoxical Sleep (PS) cycles of the polygraphically-recorded nocturnal sleep in three groups of six infants each, aged respectively 1 to 2 weeks, 15 to 19 weeks, and 25 to 47 weeks. HR decreased with age, and was higher during PS than during QS, without difference between odd QS phases (1st, 3rd and 5th, which contain always, but only in oldest infant's group, Slow wave sleep (SWS) stage 3 and 4 episodes), and even QS phases (2nd, 4th and 6th, never containing SWS episodes). In the oldest infant's group, in odd QS phase only, HR was higher in the first half with respect to the second half. The HR modulation according to the QS-PS alternance was obvious in all infant groups. In the oldest infant's group the QS phases without SWS episodes were characterized by a dissociation between EEG activity level (close to that of PS) and HR (similar to that of QS phases with SWS); in QS phases with SWS, however, the HR was modulated according to the type of EEG activity (stage 2 vs SWS).

Analysis of Variance↗
PubMed1994

Trends in electroencephalographic synchronization across nonrapid eye movement sleep in infants.

The trend of synchronized (high-voltage, low-frequency) electroencephalographic (EEG) activity was determined across nonrapid eye movement (NREM) sleep periods of night sleep in two groups of infants (eight "young infants", age 2-19 weeks; eight "older infants", age 21-54 weeks) and, a reference, in a group of eight adults (age 16-45 years). By automatic analysis of the sleep EEG, a parameter was derived that represents the degree of synchronized (high-amplitude, low-frequency) EEG activity for successive 30-second epochs. For each subject, the average level of EEG synchronization for each NREM period and the time of the NREM period midpoints were determined. In all three groups, synchronized EEG activity tended to decrease across successive NREM periods. This trend was weaker for infants than for adults and, surprisingly, weaker for older than for young infants. This suggests that the decreasing trend typical for adults is already present in the first months after birth. The difference in trend between infants and adults may be caused by differences in the 24-hour sleep-wakefulness distribution, whereas the distinction between young and older infants could be related to a restructuring of sleep in the second semester, in particular to the emergence of slow-wave sleep and its peculiar distribution across NREM periods of night sleep.

Adolescent↗
PubMed1994

Heart rate and heart rate variability during sleep in small-for-gestational age newborns.

To assess the influence of intrauterine growth retardation on heart rate (HR) and HR variability during sleep, we performed polygraphic recordings in 10 small-for-gestational age (SGA) and 16 appropriate-for-gestational age (AGA) newborns. Both groups were clinically and neurologically normal and were at 37 to 41 wk conceptional age. RR intervals were analyzed using the short-time Fourier transform in three frequency bands: 1) high frequency, with a period 3-8 heartbeat; 2) mid frequency, with a period 10-25 heartbeat; and 3) low frequency, with a period 30-100 heartbeat. In both active and quiet sleep, SGA newborns significantly differed from AGA newborns by having a shorter RR interval (p < 0.01) and lower amplitude of HR variability in all bands (p < 0.05) except low frequency in quiet sleep. Quiet sleep differed from active sleep by having a longer RR interval (p < 0.05), higher high-frequency variability (p < 0.02) in both SGA and AGA newborns, and lower low-frequency variability (p < 0.005 for AGA newborns). Our data give evidence of clear modifications of both sympathetic and parasympathetic HR control in the at-risk SGA population. Similarity of between-state characteristics suggests maintained CNS control of HR in SGA as well as in AGA newborns. We speculate that between-group HR and HR variability differences may be related to augmented metabolic rate in SGA compared with AGA newborns.

Basal Metabolism↗