Delayed sleep phase disorder during the COVID-19 pandemic and its health implications.

Circadian rhythm sleep disorders are alterations that are characterized by a shift in the sleep-wake cycle relative to day and night, such as the delayed sleep phase disorder (DSPD), which is a retard of at least 2 hours in the sleep start. Typically, the patient falls asleep after 2 a.m. and wakes up after 10 a.m. and with symptom of sleep onset insomnia. The prevalence of DSPD in young adults is 0.48%, increasing to 3.3% in adolescents. Interestingly, patients with COVID-19 infection report anxiety due to the intensive care unit lockdown and constant exposure to bright light. In addition, post-COVID patients have an increased risk of developing DSPD. For example, in adolescent post-COVID patients, the prevalence of DSPD increases to 63.3%. Patients with DSPD also have alterations in metabolic health, poor school performance, cognitive impairment, and a higher risk of developing other diseases. The objective of the present review is therefore to describe the characteristics of DSPD during the COVID-19 pandemic and to outline its possible implications for physical health (eg, metabolism) and mental health (eg, anxiety or depression).

Parasomnias in patients with addictions-a systematic review.

Parasomnias are involuntary behaviors or subjective experiences during sleep. Our objective was to review existing information on the presence of parasomnias in patients with addictions or during treatment for addictions. Information about parasomnias related to rapid-eye-movement (REM) and non-REM sleep in patients with addictions, while using substances or in abstinence, was reviewed. A systematic search of published articles reporting parasomnias as a consequence of drug use or abuse was conducted in the PubMed and SciELO databases. The search for the studies was performed in three phases: (1) by title, (2) by abstract, and (3) by complete text. The search was performed independently by two researchers, who then compared their results from each screening phase. Seventeen articles were found. The consumption of alcohol was reported in association with arousal disorders, such as sexsomnia and sleep-related eating disorder; and REM sleep behavior disorder was reported during alcohol withdrawal. Cocaine abuse was associated with REM sleep behavior disorder with drug consumption dream content. Overall, we found that several types of parasomnias were very frequent in patients with addictions. To avoid accidents in bedroom, legal problems, and improve evolution and prognosis; must be mandatory to include security measures related to sleep period; avoid pharmacological therapy described as potential trigger factor; improve sleep hygiene; and give pharmacological and behavioral treatments for patients with these comorbid sleep disorders.

Differences in electroencephalographic spectra during pre-sleep wakefulness, N1, and R sleep between comorbid insomnia and obstructive sleep apnea.

PURPOSE: The neuropsychobiological effects of the comorbidity of insomnia and obstructive sleep apnea are not well studied. Our objective was to compare electroencephalographic spectra of patients with comorbid insomnia and sleep apnea syndrome to those of patients with sleep apnea syndrome alone during pre-sleep wakefulness and the N1 and R sleep periods. METHOD: We performed electroencephalography and polysomnography on 10 patients with comorbid insomnia and sleep apnea and 10 with only sleep apnea. Electroencephalography spectra analysis was performed for absolute power in clinical bands in six derivations. RESULTS: Compared to sleep apnea patients, comorbid patients had lower sleep efficiency and total sleep time, higher beta-1 power in the left frontal and central derivations during pre-sleep wakefulness, higher delta power in the left frontal and central derivations during the N1 stage, and higher beta-2 power in the left frontal and central, and right central derivations during the R stage. CONCLUSIONS: Data suggest that patients with insomnia and sleep apnea, compared to patients with only sleep apnea, presented higher left high-frequency rhythms during pre-sleep wakefulness and R sleep stage, and may be for increased emotional and cognitive-related activity, while in stage N1, presented higher left delta power, which suggest some slowing after sleep deprivation.

Effect of age on electrical nerve conduction in the somatosensory pathway and its correlation with somatometry and plasma concentrations of musculoskeletal enzymes in male rhesus monkeys (Macaca mulatta) held in captivity.

BACKGROUND: Somatosensory evoked potentials (SEPs) make it possible to obtain functional data on the activity of somatosensory pathway. OBJECTIVE: To evaluate the ontogeny of electrical nerve conduction in male rhesus monkeys using SEPs in correlation with the development of the musculoskeletal system based on somatometry and musculoskeletal enzymes. METHODS: Somatosensory evoked potentials of the medial and tibial nerves were performed, and somatometric measurements were obtained: total length, arm and forearm length, and thigh and calf length. Analysis of the musculoskeletal enzymes, lactic dehydrogenase, and creatininase was conducted using blood samples in 20 rhesus monkeys divided into 5 groups. RESULTS: Statistical analysis manifested a delay in the appearance of latencies as age increased. Also evident was a strong, direct relation between the lengths and the value of the latencies of the SEP, together with an inverse relation between the musculoskeletal enzymes. CONCLUSIONS: These findings contribute to standardizing this animal model in the neurophysiological sciences.

[Comparación de síntomas de hiperactividad e inatención en adolescentes con y sin antecedentes de embarazo].

Introduction: Teenage pregnancy has a negative impact both on mother's health and on her offspring quality life and development. In spite of its important social relevance, behavioral factors that can favor its occurrence have not been extensively explored. Objective: To compare symptoms of inattention and hyperactivity between adolescents with and without a history of pregnancy. Method: A sociodemographic record and the attention deficit hyperactivity disorder questionnaire (ADD) of the Neuropsi instrument were applied to 60 adolescents: 30 cases and 30 controls. The ADD was answered by the adolescents themselves, as well as by a close relative (parent or spouse) or by one of their teachers. Results: From the perspective of others (parents and teachers), adolescents with a history of pregnancy showed more symptoms of attention deficit and higher attention deficit and hyperactivity overall score (both p ≤ 0.01). In addition, ADD overall score was found to be associated with adolescent pregnancy (OR = 1.11, 95% CI = 1.01-1.24, p = 0.036). Conclusions: Symptoms of attention deficit and hyperactivity can represent another factor associated with teenage pregnancy.

Introducción: El embarazo adolescente ejerce un impacto negativo tanto en la salud de la madre como en la calidad de vida y desarrollo de sus hijos. Pese a su importante carga social, no se han explorado con detalle los factores conductuales que pueden favorecer su presencia. Objetivo: Comparar los síntomas de inatención e hiperactividad entre adolescentes con y sin antecedente de embarazo. Método: A 60 adolescentes se aplicó una ficha de datos sociodemográficos y el Cuestionario de Trastorno por Déficit de Atención e Hiperactividad (DDA) del Neuropsi, 30 casos y 30 controles. El DDA fue contestado por las propias adolescentes, así como por un familiar cercano (padre o pareja) y/o por un profesor del adolescente. Resultados: Desde la perspectiva de los otros (padres y profesores), las adolescentes con antecedentes de embarazo presentaron más síntomas de déficit de atención y mayor puntuación global de déficit de atención e hiperactividad (ambas con p ≤ 0.01). Asimismo, se encontró que la puntuación global del DDA se asoció con el embarazo adolescente (RM = 1.11, IC 95 % = 1.01-1.24, p = 0.036). Conclusiones: Los síntomas de déficit de atención e hiperactividad pueden representar otro factor asociado con el embarazo adolescente.

Psychoacoustics and Neurophysiological Alterations after 30-36 Hours of Sleep Deprivation.

BACKGROUND AND AIM: Sleep deprivation (SD) may result in perceptual and cognitive alterations in healthy subjects. Our objective was to compare whether psychoacoustics and neurophysiological variables in healthy subjects were altered after SD of 30-36 h. METHOD: We examined 22 subjects by means of several psychoacoustics tests, P300 and mismatch negativity (MMN) recordings, and brainstem auditory evoked potentials (BAEP) before and after 30-36 h of SD. RESULTS: In the psychoacoustics tests, we found that after SD, difficulties were experienced by the left ear in the discrimination of words in noise and by the right ear in music discrimination. In the neurophysiological tests, we found delayed latencies of P300 and MMN wave; there was a delay of wave I in both ears, and wave V in the right ear in BAEP. We found significant correlations with positive direction between P300 latency and words in noise and music discrimination in the right ear. CONCLUSIONS: SD results in alterations of central auditory processing perception and delays of brain neurophysiological responses, with some correlations between the psychoacoustics and neurophysiological tests. These alterations may relate to other cognitive alterations that deserve more research in future studies.

Effect of late-onset fetal growth restriction on organization of behavioral state in infants.

BACKGROUND: The aim of this study was to analyze whether late-onset fetal growth restriction (FGR) alters regulatory capability in infants, and whether this can be detected using both the neonatal behavior assessment scale (NBAS) and brainstem auditory-evoked potentials (BAEP). METHODS: The diagnosis of FGR was made on Doppler examination in the third trimester of pregnancy. NBAS and BAEP measurement were performed at 1 month of corrected postnatal age. RESULTS: The group with late-onset FGR was integrated with 17 infants and the control group consisted of 14 subjects. The NBAS range of state score, which reflects organization of behavioral state, was low in infants with late-onset FGR. No differences were found in BAEP between groups. No association between NBAS and BAEP was detected. CONCLUSION: Late-onset FGR has a deleterious effect on NBAS range of state, but possibly does not alter BAEP response. It is proposed that regulatory capabilities in the neonatal period play a primary role in subtle cognitive difficulties in infants with late-onset FGR in the long term.

[The auditory pathway: levels of integration of information and principal neurotransmitters]. / La vía auditiva: niveles de integración de la información y principales neurotransmisores.

In this paper we studied the central auditory pathway (CAP) from an anatomical, physiological and neurochemical standpoint, from the inner ear, brainstem, thalamus to the temporal auditory cortex. The characteristics of the spiral ganglion of Corti, auditory nerve, cochlear nuclei, superior olivary complex, lateral lemniscus, inferior colliculus, medial geniculate body, and auditory cortex, including the auditory efferent pathway, are given. CAP is described as the electrical impulses, travelling through axons, allowing ions to enter a neuron and vesicles with neurotransmitters (NT) and then released into synaptic space. The NT changes the functioning of the cells; when attached to specific receptors on the next nerve cell, NT-receiver union causes input of ions through Gap sites, resulting in a postsynaptic potential that is spread over all CAP. In addition, the effects of the NT are not limited to the transmission, but as trophic agents that promote the formation of new neural networks. Even the anatomy, physiology, neurochemical aspects, and the different types of synapses are not fully understood to comprehend the organization of the CAP, but remain under investigation because of the relevance for the treatment of various central auditory disorders.

[Neuropsychological intervention in memory consolidation in patients with acoustic-mnestic aphasia. An exploratory and preliminary study]. / Intervención neuropsicológica en la consolidación de la memoria en pacientes con afasia acústico-amnésica. Estudio exploratorio y preliminar.

Neuropsychological alterations after stroke depend on the type and site of the injury and may result in cognitive, mood or social disabilities. The disorders may disturb daily motor activities and may alter language and short- and long-term memory. Patients that have suffered a stroke in the left temporal hemisphere may present acoustic-mnestic aphasia and memory alterations. Our objective was to evaluate the results of the implementation of a memory reinforcement training program in patients with acoustic-mnestic aphasia, and to know if the program improves memory consolidation for a better patient's quality of life. We performed a case-report study, before and after implementation of a memory reinforcement program in two patients with acoustic-mnestic aphasia and memory alterations. The program was constructed with 20 supra-ordinal categories, each with 10 sub-ordinal words, with a total of 200 words to evoke. We found significant differences in the number of evoked words and in memory consolidation after the implementation of the program in the two studied patients. Our observations suggest that implementation of a memory reinforcement program in subjects with acoustic-mnestic aphasia may be useful in the rehabilitation of memory alterations in these patients.

Parasomnias related to shift work disorder among medical residents during the first year of training in Mexico.

Shift work disorder (SWD) may affect medical residents because their workload, academic demands and extended work hours. This condition set residents at risk of more sleep disorders. The study compared parasomnias among residents with and without shift work disorder (SWD) and weighed their relative risk (RR) for each parasomnia. One hundred twenty-six residents participated in the study. The Munich Parasomnia Screening questionnaire and the Barger Questionnaire for SWD were used for the screening of parasomnias and SWD, respectively. Means and percentages of studied variables were compared between groups. Relative risk (RR) was calculated for each type of parasomnia. The more frequent parasomnias in residents with SWD the RR (and 95% confidence intervals) were: sleep terrors, 5.60 (1.84-17.01); confusional arousals, 3.73 (1.84-7.56); sleep paralysis, 3.27 (1.53-6.93); hypnagogic/hypnopompic hallucinations, 2.55 (1.03-6.28); somniloquies, 2.45 (1.21-4.92); and nightmares, 2.01 (1.54-2.62). Our data suggest that residents who experience SWD may be at risk of having lower threshold for the occurrence of rapid eye movement (REM) and non-REM (NREM) sleep parasomnias. Additional research is needed to confirm these results, and to further identify the contribution to this association.

Risk factors associated with retinopathy of prematurity and visual alterations in infants with extremely low birth weight.

OBJECTIVE: Retinopathy of prematurity (RoP) is a retinal vascular disease and a frequent cause of blindness in infants. Our objective was to measure the frequency of RoP in infants with extremely low birth weight (ELBW, < 1,000 g) at the National Institute of Perinatology, Neonatal Intensive Care Unit (NICU), weighing the association of RoP with several risk factors and their results, such as refractive errors and strabismus. MATERIAL AND METHODS: We carried out two cross-sectional observations of our prospective study: one near birth, and the second, after a long-term follow-up. Funduscopic examination was performed while the infants were in the NICU to detect RoP. Infants with RoP were followed up by means of visual examinations during an average 8-year period and results were compared with those of infants with ELBW without RoP. RESULTS: Of the 139 screened infants at the NICU, 24.4% were identified with RoP: 79% of these with grade I retinopathy; 18% with grade II, and one infant with grade III retinopathy. The zones involved were as follows: zone 1, 12%; zone 2, 79%, and zone 3, 9%. The following were associated with retinopathy: eclampsia (p = 0.003); gestational age (0.01); multiple gestation (0.03); days of stay at NICU (< 0.001); mechanical ventilation (0.001); hypoxia (0.01); oxygen therapy (< 0.001); apnea (0.005); acidosis (0.001), and hypercapnia (0.001). Retinopathy was self-limited in all children. We found no differences in frequency of refractive errors and strabismus between children with RoP and controls. CONCLUSIONS: We observed a moderately high frequency of RoP in infants with ELBW in Mexico City and recommended early mandatory screening for early intervention.

Characterization of cyclic alternating pattern in infants with laryngomalacia.

Objective: Cyclic alternanting pattern (CAP) has been considered a marker of sleep instability in children. The aim of this study was to evaluate the CAP in infants with laryngomalacia. Material and Methods: CAP were quantified in 15 infants with laryngomalacia (mean age 167.2±97.21 days) and 10 controls (mean age of 158.5±116.2 days) using polysomnography. Results: The distribution of the A2 subtypes across NREM stages in infants with laryngomalacia showed a decrease, as well as in the mean duration of CAP sequences. The A3 CAP and arousals increased in infants with laryngomalacia. Our data showed a stronger correlation between the mean duration of A1 CAP and the age in healthy controls than in infants with laryngomalacia. In accordance to previous reports infants with laryngomalacia exhibited an increase in total awake time, apnea-hypopnea index, and a decrease in N3 stage compared to controls. Discussion: Our findings add to a growing body of literature of CAP as an indicator of brain maturation.

Identification of attention-deficit-hyperactivity disorder and conduct disorder in Mexican children by the scale for evaluation of deficit of attention and hyperactivity.

The objective was weighing the usefulness of a Spanish-language Scale for the evaluation of deficit of attention and hyperactivity (EDAH) to identify children with attention deficit-hyperactivity disorder (AD-HD) and conduct disorder (CD) in a sample of school-aged children. We studied 132 children from a government-run public elementary school previously selected by teachers as having learning and attention disorders. We screened children of the sample with parents' and teachers' EDAH and Diagnostic and Statistical Manual of Mental Disorders-IV edition Text Revision (DSM-IV-TR) questionnaires, and performed an interdisciplinary clinical examination for the final diagnosis. We found 81 children with AD-HD and 51 children without AD-HD. AD-HD was classified as follows: AD-HD-combined (-C), n=32; AD-HD-inattentive (-I), n=17 and AD-HD-hyperactive (-H), n=32. Cronbach's alpha calculation for the EDAH parents' questionnaire was 0.76, and for teachers, 0.80. Sensitivity of the teachers' EDAH questionnaire was 0.94, and specificity, 0.91. Sensitivity of the parents' EDAH questionnaire was 0.91, while specificity was 0.87. The data of EDAH parents' and teachers' questionnaires have a concordance of 93.1% and 80%, respectively. The correlation of scores among parents' and teachers' EDAH scales was significant. The correlation between results from parents' and teachers' DSM-IV-TR and EDAH questionnaires was also significant. Our results partially support the use of EDAH questionnaires for AD-HD and CD screening in Spanish-speaking populations.

Habituation Alteration in Infants with Periventricular Echogenicity as an Indicator of Neurocognitive Impairment.

Habituation difficulties may suggest neurocognitive impairment. Periventricular echogenicity (PVE) potentially causes subtle damage that poses neuropsychological risk. Habituation was evaluated through heart rate and behavioral states in infants at 36-37 weeks of corrected age between control and PVE groups. PVE infants showed early alertness and abrupt changes in behavioral states. However, the comparison group could better regulate their states. Heart rate was significantly high and remained unchanged in the PVE group but decreased in the control group. Alterations during the habituation paradigm in PVE infants could be early indicators of neuropsychological risk impairment. Scope of early habituation assessment is discussed.

Maternal smoking during pregnancy and physiological anxiety in children with attention deficit hyperactivity disorder.

Our objective was to explore the relationship between mother smoking during pregnancy and physiological anxiety of children with Attention deficit-hyperactivity disorder. Cognitive profile was evaluated by Wechsler Intelligence Scale for Children, physiological anxiety by Children's Manifest Anxiety Scale. Mother's smoking was evaluated by the Fagerström test for nicotine dependence. Ninety-seven children with Attention Deficit-Hyperactivity Disorder combined type, 70 inattentive, and 48 hyperactive-impulsive, and 130 controls were studied. We found a higher frequency of high smoking dependence in mothers of children with Attention Deficit-Hyperactivity Disorder-combined type, and Attention Deficit Hyperactivity Disorder-hyperactive type in the Fagerström test; and a significant correlation between physiological anxiety in children with Attention Deficit Hyperactivity Disorder-combined type, with high and moderate maternal smoking level during pregnancy. In conclusion, data suggests, with caution a brain alteration of infants, induced by nicotine exposure during pregnancy in children with Attention Deficit Hyperactivity Disorder-combined type, and Attention Deficit Hyperactivity Disorder-hyperactive type.

Body mass index in offspring of mothers with diabetes mellitus: follow-up at 2, 4, 6, and 8 years of age.

Background: Offspring of mothers with diabetes mellitus (DM) during pregnancy may be at high risk for developmental alterations. This study aimed to identify the effects of maternal pre- and gestational diabetes on the body mass index of infants and children at two, four, six, and eight years of age. Methods: We studied children of mothers with type 1, type 2, and gestational diabetes and a control group. Maternal and neonatal variables were analyzed for associations with children overweight/obesity. Results: Mothers with DM were older than controls (32 ± 6 vs. 22 ± 6 years, p < 0.001). The frequency of preeclampsia in mothers with DM was 28%. Gestational age and weight at birth were lower in infants from the groups of mothers with DM in comparison with controls (32.8 ± 3.1 vs. 36.4 ± 2.2 weeks, p < 0.001, and 1,637 ± 600 vs. 2,208 ± 518 g, p < 0.001, respectively). At 8 years of age, 47% of the offspring of mothers with DM type 2 had overweight/obesity (odds ratio (OR 8.25) 95% confidence interval (CI) 1.3-51, p = 0.01), while 27% of offspring of mothers with type 1 DM had overweight/obesity, and 10% of offspring of mothers with gestational diabetes presented overweight/obesity. Conclusions: Offspring of pre-gestational DM mothers have a higher risk to develop overweight/obesity, as was observed with follow-up until school age, for which they require continuous vigilance.

Introducción: Los hijos de madres con diabetes mellitus durante el embarazo pueden tener un alto riesgo de alteraciones del desarrollo. El objetivo de este estudio fue buscar los efectos de la diabetes pregestacional y gestacional en el índice de masa corporal de niños a los 2, 4, 6 y 8 años de edad. Métodos: Se estudiaron los hijos de madres con diabetes tipo 1, 2 y gestacional, así como un grupo control. Se analizaron las variables maternas y neonatales en búsqueda de una asociación con sobrepeso u obesidad en los niños. Resultados: La edad de las madres con diabetes mellitus fue mayor que la del grupo control (32 ± 6 vs. 22 ± 6 años, p < 0.001). La frecuencia de preeclampsia en las madres con diabetes mellitus fue del 28%. La edad gestacional y el peso al nacer fueron menores en los hijos de las madres con diabetes en comparación con los controles (32.8 ± 3.1 vs 36.4 ± 2.2 semanas, p < 0.001, y 1,637 ± 600 vs. 2,208 ± 518 g, p < 0.001, respectivamente). A los 8 años, el 47% de los hijos de madres con diabetes tipo 2 tuvieron sobrepeso u obesidad (RM: 8.25; intervalo de confianza del 95%: 1.3-51; p = 0.01), frente al 27% de los hijos de madres con diabetes tipo 1 y el 10% de los hijos de madres con diabetes gestacional. Conclusiones: Los hijos de madres con diabetes pregestacional presentan un mayor riesgo de desarrollar sobrepeso u obesidad, como se observó en el seguimiento hasta la edad escolar, por lo que requieren una vigilancia continua.

Risk factor frequency for learning disabilities in low socioeconomic level preschool children in Mexico city.

The objective was to identify the frequency of risk factors for Learning Disabilities (LD) in low socioeconomic level children in Mexico City. We studied children by means of: Wechsler, Bender-Gestalt, and Human drawing tests. Average age of male subjects was 5.6±0.9 years, while that of the female group was 5.4±0.5 years. In male subjects, average Total intelligence quotient (T-IQ) score was 98±12.2 while, in the female group, this was 99±12.2. On the Bender-Gestalt test, male subjects had a mental and visual-motor average age of <1 year under chronological age. Female subjects had a mental and visual-motor age 8-7 months under the norm. On the Human drawing test, in male and female subjects, the most frequent at-risk features comprised: self-isolation in 25% of subjects, shyness in 22.4%, and poor internal controls in 22%. In conclusion, we found a high at-risk factor frequency for LD in children of low socioeconomic strata. We highlight the importance of screening children before they attain school age.

Lateralization of the Dichotic Digits Test, Central Auditory Processes, and Evoked Potentials in Multiple Sclerosis.

Lateralization for central auditory processing (CAP) with dichotic digits recognition (DDR) test is believed expression of hemispheric dominance. Multiple sclerosis (MS) is considered an inflammatory and autoimmune alteration of central nervous system (CNS). Hearing alterations in MS and their role in CAP has not been well studied. A patient with MS and new kind of alteration in lateralization of CAP with DDR test is presented. A 53 year of age female with MS of 16 years of evolution, nine of them remained asymptomatic. She has a persistent advantage of the right ear for DDR test; but other monaural tests showed predominance of the left afferent pathway. Brainstem auditory evoked potentials (BAEPs) and long latency auditory evoked potentials (LLAEPs) showed adequate right response with deficits in organization of left response in BAEP, and N2 wave. In the contrary direction of previous publication, we disclosed advantage for DDR test, BAEP, and LLAEP in the right ear. We observed no left ear suppression; with predominance of correct left percentages in monaural psychoacoustics tests. We must keep on searching to find pathophysiological meaning of predominant of right or left auditory laterality as a CAP disorder in patients with MS.

Fetal growth restriction: From Polyvagal theory to developmental impairments?

BACKGROUND: The Polyvagal theory argues that behavioral modulation is a fundamental neurodevelopmental process that depends on autonomic regulation. OBJECTIVE: The present study aimed to assess sleep architecture in newborns with fetal growth restriction (FGR) using polysomnography as an indicator of Polyvagal theory. METHODS: We studied polysomnography recordings from 68 preterm infants, 34 with FGR and 34 born with appropriate growth for gestational age (AGA), who were matched according to the corrected age for prematurity (CA). Total sleep time, arousals, the percentage of quiet sleep, active sleep, indeterminate sleep, and heart rate were compared between the groups. Linear multiple regression analyses were used to evaluate polysomnography data for the FGR and AGA groups. RESULTS: Average heart rate was significantly lower in most FGR groups compared with AGA groups, and small to large effect sizes were observed in several sleep responses when comparing these groups. In the lineal regression model the CA explains significantly the differences in heart rate, controlled by FGR (p = .012). Additionally, there was evidence that sleeping states show similar trends, that is, increases in quiet and indeterminate sleep, as well as decreases in active sleep when CA was controlled by FGR. CONCLUSION: FGR probably intensifies the unfavorable effect of preterm birth in the responses evaluated by polysomnography. It seems that FGR is associated with alteration in sleep regulation and with differences in heart rate modulation, which may serve as a strategy to preserve energy and such differences likely underlie neurodevelopmental impairments in affected newborns.

Effect of different anesthetic mixtures-ketamine-xylazine, ketamine-acepromazine and tiletamine-zolazepam-on the physiological and blood biochemistry parameters of male rhesus monkeys (Macaca mulatta) at different ages.

BACKGROUND: Anesthetic agents are commonly utilized in the handling of non-human primates for prevent the stress caused in physical exploration or physical restrain. For this reason, the objective of this work was to describe the effect of age and dissociative anesthetics (ketamine and tiletamine), and their combinations with acepromazine, xylazine and zolazepam, on the physiological and blood biochemical parameters in Macaca mulatta. METHODS: Eighty male Macaca mulatta were divided into four experimental groups depending on the anesthetic mixture applied. Each group of 20 males was divided into five sub-groups according to age. Physiological parameters were recorded every 5 minutes during a 30-minute period. A blood sample was drawn to analyze blood biochemistry. RESULTS: Statistical analyses revealed significant differences in the physiological parameters between the ketamine-acepromazine and ketamine-xylazine groups compared to the control group. The analysis of blood biochemistry found significant differences by age and by anesthetic mixture among all groups. CONCLUSION: These findings contribute to standardizing this animal model in biological research.