Linear hair growth rates in preschool children.

BACKGROUND: Human scalp hair is a validated bio-substrate for monitoring various exposures in childhood including contextual stressors, environmental toxins, prescription or non-prescription drugs. Linear hair growth rates (HGR) are required to accurately interpret hair biomarker concentrations. METHODS: We measured HGR in a prospective cohort of preschool children (N = 266) aged 9-72 months and assessed demographic factors, anthropometrics, and hair protein content (HPC). We examined HGR differences by age, sex, race, height, hair pigment, and season, and used univariable and multivariable linear regression models to identify HGR-related factors. RESULTS: Infants below 1 year (288 ± 61 µm/day) had slower HGR than children aged 2-5 years (p = 0.0073). Dark-haired children (352 ± 52 µm/day) had higher HGR than light-haired children (325 ± 50 µm/day; p = 0.0019). Asian subjects had the highest HGR overall (p = 0.016). Younger children had higher HPC (p = 0.0014) and their HPC-adjusted HGRs were slower than older children (p = 0.0073). Age, height, hair pigmentation, and HPC were related to HGR in multivariable regression models. CONCLUSIONS: We identified age, height, hair pigment, and hair protein concentration as significant determinants of linear HGRs. These findings help explain the known hair biomarker differences between children and adults and aid accurate interpretation of hair biomarker results in preschool children. IMPACT: Discovery of hair biomarkers in the past few decades has transformed scientific disciplines like toxicology, pharmacology, epidemiology, forensics, healthcare, and developmental psychology. Identifying determinants of hair growth in children is essential for accurate interpretation of hair biomarker results in pediatric clinical studies. Childhood hair growth rates define the time-periods of biomarker incorporation into growing hair, essential for interpreting the biomarkers associated with environmental exposures and the mind-brain-body connectome. Our study describes age-, sex-, and height-based distributions of linear hair growth rates and provides determinants of linear hair growth rates in a large population of children. Age, height, hair pigmentation, and hair protein content are determinants of hair growth rates and should be accounted for in child hair biomarkers studies. Our findings on hair protein content and linear hair growth rates may provide physiological explanations for differences in hair growth rates and biomarkers in preschool children as compared to adults.

The social ecology of childhood and early life adversity.

An increasing prevalence of early childhood adversity has reached epidemic proportions, creating a public health crisis. Rather than focusing only on adverse childhood experiences (ACEs) as the main lens for understanding early childhood experiences, detailed assessments of a child's social ecology are required to assess "early life adversity." These should also include the role of positive experiences, social relationships, and resilience-promoting factors. Comprehensive assessments of a child's physical and social ecology not only require parent/caregiver surveys and clinical observations, but also include measurements of the child's physiology using biomarkers. We identify cortisol as a stress biomarker and posit that hair cortisol concentrations represent a summative and chronological record of children's exposure to adverse experiences and other contextual stressors. Future research should use a social-ecological approach to investigate the robust interactions among adverse conditions, protective factors, genetic and epigenetic influences, environmental exposures, and social policy, within the context of a child's developmental stages. These contribute to their physical health, psychiatric conditions, cognitive/executive, social, and psychological functions, lifestyle choices, and socioeconomic outcomes. Such studies must inform preventive measures, therapeutic interventions, advocacy efforts, social policy changes, and public awareness campaigns to address early life adversities and their enduring effects on human potential. IMPACT: Current research does not support the practice of using ACEs as the main lens for understanding early childhood experiences. The social ecology of early childhood provides a contextual framework for evaluating the long-term health consequences of early life adversity. Comprehensive assessments reinforced with physiological measures and/or selected biomarkers, such as hair cortisol concentrations to assess early life stress, may provide critical insights into the relationships between early adversity, stress axis regulation, and subsequent health outcomes.

Demographic and psychosocial factors associated with hair cortisol concentrations in preschool children.

BACKGROUND: Early life stress has enduring effects on physical and mental health. Hair cortisol concentrations (HCCs) reflect exposures to contextual stressors in early life, but are understudied in preschool children. METHODS: Hair samples from children (N = 693) during clinic visits (CVs) scheduled at 1-4 years (CV1-CV4) were measured using validated assay methods for HCC. RESULTS: HCCs were highest at CV1 and decreased at CV2-CV4, with no sex differences. Black children had higher HCC than White/other children; these differences persisted even after adjusting for socioeconomic factors. Bivariable analyses showed significant effects on HCC for Black race, with specific demographic and psychosocial factors at different ages. Multivariable analyses showed that higher HCC at CV1 were associated with Black race and male sex; at CV2 with Black race, lower maternal self-esteem, socioeconomic adversity, and the child's risk for developmental delay; at CV3 with Black race; at CV4 with maternal depression and the child's prior HCC values. CONCLUSIONS: HCCs were higher in Black children than White/other races; differences were related to maternal factors, socioeconomic adversity, and the child's risk for developmental delay. Public health measures to reduce disparities between Blacks and other races must also consider the long-term effects of chronic stress in early life.

Measuring socioeconomic adversity in early life.

AIM: Early life adversity leads to enduring effects on physical and mental health, school performance and other outcomes. We sought to identify potentially modifiable factors associated with socioeconomic adversity in early life. METHODS: We enrolled 1503 pregnant women aged 16-40 years, without pregnancy complications or pre-existing conditions from Shelby County, Tennessee. Social, familial and economic variables were analysed using principal components (PCs) analyses to generate the Socioeconomic Adversity Index (SAI). This was replicated using the National Survey of Children's Health (NSCH). Health and social outcomes were compared across the quintile groups defined by SAI values at the county, state and national levels. RESULTS: Significant differences occurred across the SAI Quintile-1 to Quintile-5 groups in marital status, household structure, annual income, education and health insurance. Significantly worse health and social outcomes occurred in the lower versus higher SAI quintiles, including maternal depression, parental incarceration, child's birthweight and potential for child abuse. Maternal age and race also differed significantly across the SAI quintiles. CONCLUSION: Modifiable factors contributing to socioeconomic adversity in early life included marital status, household structure, annual income, education and health insurance. Those exposed to greater socioeconomic adversity as defined by SAI values had significantly worse maternal and child outcomes.

Respiratory Syncytial Virus Disease Is Mediated by Age-Variable IL-33.

Respiratory syncytial virus (RSV) is the most common cause of infant hospitalizations and severe RSV infections are a significant risk factor for childhood asthma. The pathogenic mechanisms responsible for RSV induced immunopathophysiology remain elusive. Using an age-appropriate mouse model of RSV, we show that IL-33 plays a critical role in the immunopathogenesis of severe RSV, which is associated with higher group 2 innate lymphoid cells (ILC2s) specifically in neonates. Infection with RSV induced rapid IL-33 expression and an increase in ILC2 numbers in the lungs of neonatal mice; this was not observed in adult mice. Blocking IL-33 with antibodies or using an IL-33 receptor knockout mouse during infection was sufficient to inhibit RSV immunopathogenesis (i.e., airway hyperresponsiveness, Th2 inflammation, eosinophilia, and mucus hyperproduction); whereas administration of IL-33 to adult mice during RSV infection was sufficient to induce RSV disease. Additionally, elevated IL-33 and IL-13 were observed in nasal aspirates from infants hospitalized with RSV; these cytokines declined during convalescence. In summary, IL-33 is necessary, either directly or indirectly, to induce ILC2s and the Th2 biased immunopathophysiology observed following neonatal RSV infection. This study provides a mechanism involving IL-33 and ILC2s in RSV mediated human asthma.

Regulation of inflammatory biomarkers by intravenous methylprednisolone in pediatric ARDS patients: Results from a double-blind, placebo-controlled randomized pilot trial.

OBJECTIVE: A double-blind, randomized controlled trial showed that low-dose glucocorticoid therapy in pediatric ARDS patients is feasible and may improve both ventilation and oxygenation indices in these patients. However, the molecular mechanisms underlying potential changes in outcomes remain unclear. Based on these clinical findings, this study was designed to examine the effects of intravenous methylprednisolone on circulating inflammatory biomarkers in pediatric ARDS patients. DESIGN: Double-blind, placebo-controlled randomized trial with blood collection on study entry and day 7. SETTING: Tertiary care children's hospital. PATIENTS: Children (0-18years) with ARDS undergoing mechanical ventilation. INTERVENTIONS: 35 children were randomized within 72h of mechanical ventilation. The glucocorticoid group received methylprednisolone 2mg/kg loading dose followed by 1mg/kg/day continuous infusion from days 1 to 7. Both groups were ventilated following the ARDSnet recommendations. WBC and differential cell counts, plasma cytokines and CRP levels, and coagulation parameters were analyzed on days 0 and 7. RESULTS: At study entry, the placebo group had higher IL-15 and basophil levels. On day 7, in comparison to study entry, the placebo group had lower IL-1α, IFN-γ and IL-10 levels. The glucocorticoid group had lower INF-α, IL-6, IL-10, MCP-1, G-CSF and GM-CSF levels, and higher IL-17α levels on day 7 in comparison to study entry. Total and differential cell counts remained unchanged within the placebo group between days 0 and 7, whereas in the glucocorticoid group total WBC and platelets counts were increased on day 7. Pearson's correlation studies within the placebo and glucocorticoid groups revealed positive and negative correlations between cytokine levels, cell counts, coagulation parameters and relevant clinical parameters of disease severity identified in our previous study. Multiple regression models identified several cytokines as predictors for alterations in clinical parameters of disease severity. CONCLUSION: This pilot study shows the feasibility of simultaneously measuring multiple inflammatory cytokines, cell counts and coagulation parameters in pediatric ARDS patients. We report statistical models that may be useful for future, larger trials to predict ARDS severity and outcomes.

Inverse Relationship between Cardio-Ankle Vascular Index and Body Mass Index in Healthy Children.

OBJECTIVE: To establish reference scores for cardio-ankle vascular index (CAVI), a noninvasive measure of vascular function, which reflects the stiffness of arteries, in healthy children, to test for racial and ethnic differences, and to compare CAVI scores between overweight and normal weight children. STUDY DESIGN: Subjects included 292 children aged 10-18 years: 100 non-Hispanic whites, 89 non-Hispanic blacks, and 103 Hispanics. Subjects were grouped as normal weight (body mass index [BMI] <85th percentile for age) and overweight (BMI >85th percentile for age). Blood pressure (BP) and CAVI scores were measured in all subjects. RESULTS: After controlling for age, sex, and BMI, normal weight black males had a higher CAVI score (indicating stiffer arteries) in comparison with Hispanic males and white males (5.53 ± 0.15 vs 5.13 ± 0.15 vs 5.02 ± 0.15, P = .04). BMI had an inverse association on the CAVI score (r = -0.335, P < .0001). In multivariable analysis, BMI and average CAVI scores were significant predictors of each other (R(2) = 0.37, P < .0001, R(2) = 0.21, P < .0001). There was no significant correlation between CAVI scores and resting BP values, confirming that CAVI scores were independent of concurrent BP values. CONCLUSIONS: Significant differences in vascular function exist among ethnic groups of children. Overweight children had lower CAVI scores, suggestive of vascular adaptation to obesity in early life. CAVI, by providing a noninvasive measure of vascular health, may help identify children at increased risk for cardiovascular disease.

Methodological Considerations for Hair Cortisol Measurements in Children.

BACKGROUND: Hair cortisol levels are used increasingly as a measure for chronic stress in young children. We propose modifications to the current methods used for hair cortisol analysis to more accurately determine reference ranges for hair cortisol across different populations and age groups. METHODS: The authors compared standard (finely cutting hair) versus milled methods for hair processing (n = 16), developed a 4-step extraction process for hair protein and cortisol (n = 16), and compared liquid chromatography-mass spectrometry (LC-MS) versus enzyme-linked immunosorbent assays (ELISAs) for measuring hair cortisol (n = 28). The extraction process included sequential incubations in methanol and acetone, repeated twice. Hair protein was measured through spectrophotometric ratios at 260/280 nm to indicate the hair dissolution state using a BioTek plate reader and dedicated software. Hair cortisol was measured using an ELISA assay kit. Individual (n = 13), pooled hair samples (n = 12) with high, intermediate, and low cortisol values, and the ELISA assay internal standards (n = 3) were also evaluated by LC-MS. RESULTS: Milled and standard methods showed highly correlated hair cortisol (rs = 0.951, P < 0.0001) and protein values (rs = 0.902, P = 0.0002), although higher yields of cortisol and protein were obtained from the standard method in 13 of 16 and 14 of 16 samples, respectively (P < 0.05). Four sequential extractions yielded additional amounts of protein (36.5%, 27.5%, 30.5%, 3.1%) and cortisol (45.4%, 31.1%, 15.1%, 0.04%) from hair samples. Cortisol values measured by LC-MS and ELISA were correlated (rs = 0.737; P < 0.0001), although cortisol levels [median (interquartile range)] detected in the same samples by LC-MS [38.7 (14.4-136) ng/mL] were lower than that by ELISA [172.2 (67.9-1051) ng/mL]. LC-MS also detected cortisone, which comprised of 13.4% (3.7%-25.9%) of the steroids detected. CONCLUSIONS: Methodological studies suggest that finely cutting hair with sequential incubations in methanol and acetone, repeated twice, extracts greater yields of cortisol than does milled hair. Based on these findings, at least 3 incubations may be required to extract most of the cortisol in human hair samples. In addition, ELISA-based assays showed greater sensitivity for measuring hair cortisol levels than LC-MS-based assays.

Double-blind, placebo-controlled pilot randomized trial of methylprednisolone infusion in pediatric acute respiratory distress syndrome.

OBJECTIVE: Low-dose methylprednisolone therapy in adults with early acute respiratory distress syndrome reduces systemic inflammation, duration of mechanical ventilation, and ICU length of stay. We report a pilot randomized trial of glucocorticoid treatment in early pediatric acute respiratory distress syndrome. DESIGN: Double-blind, placebo-controlled randomized clinical trial. SETTING: Le Bonheur Children's Hospital, Memphis, TN. PATIENTS: Children (0-18 yr) with acute respiratory distress syndrome undergoing mechanical ventilation. INTERVENTIONS: Patients were randomly assigned to steroid or placebo groups within 72 hours of intubation. IV methylprednisolone administered as loading dose (2 mg/kg) and continuous infusions (1 mg/kg/d) on days 1-7 and then tapered over days 8-14. Both groups were ventilated according to the Acute Respiratory Distress Syndrome Network protocol modified for children. Daily surveillance was performed for adverse effects. MEASUREMENTS AND MAIN RESULTS: Thirty-five patients were randomized to the steroid (n = 17, no death) and placebo groups (n = 18, two deaths). No differences occurred in length of mechanical ventilation, ICU stay, hospital stay, or mortality between the two groups. At baseline, higher plateau pressures (p = 0.006) and lower Pediatric Logistic Organ Dysfunction scores (p = 0.04) occurred in the steroid group; other characteristics were similar. Despite higher plateau pressures on days 1 (p = 0.006) and 2 (p = 0.025) due to poorer lung compliance in the steroid group, they had lower PaCO2 values on days 2 (p = 0.009) and 3 (p = 0.014), higher pH values on day 2 (p = 0.018), and higher PaO2/FIO2 ratios on days 8 (p = 0.047) and 9 (p = 0.002) compared with the placebo group. Fewer patients in the steroid group required treatment for postextubation stridor (p = 0.04) or supplemental oxygen at ICU transfer (p = 0.012). Steroid therapy was not associated with detectable adverse effects. CONCLUSION: This study demonstrates the feasibility of administering low-dose glucocorticoid therapy and measuring clinically relevant outcomes in pediatric acute respiratory distress syndrome. Changes in oxygenation and/or ventilation are consistent with early acute respiratory distress syndrome pathophysiology and results of similar clinical trials in adults. We propose and design a larger randomized trial to define the role of glucocorticoid therapy in pediatric acute respiratory distress syndrome.

Deficiency of the two-pore-domain potassium channel TREK-1 promotes hyperoxia-induced lung injury.

OBJECTIVES: We previously reported the expression of the two-pore-domain K channel TREK-1 in lung epithelial cells and proposed a role for this channel in the regulation of alveolar epithelial cytokine secretion. In this study, we focused on investigating the role of TREK-1 in vivo in the development of hyperoxia-induced lung injury. DESIGN: Laboratory animal experiments. SETTING: University research laboratory. SUBJECTS: Wild-type and TREK-1-deficient mice. INTERVENTIONS: Mice were anesthetized and exposed to 1) room air, no mechanical ventilation, 2) 95% hyperoxia for 24 hours, and 3) 95% hyperoxia for 24 hours followed by mechanical ventilation for 4 hours. MEASUREMENTS AND MAIN RESULTS: Hyperoxia exposure accentuated lung injury in TREK-1-deficient mice but not controls, resulting in increase in lung injury scores, bronchoalveolar lavage fluid cell numbers, and cellular apoptosis and a decrease in quasi-static lung compliance. Exposure to a combination of hyperoxia and injurious mechanical ventilation resulted in further morphological lung damage and increased lung injury scores and bronchoalveolar lavage fluid cell numbers in control but not TREK-1-deficient mice. At baseline and after hyperoxia exposure, bronchoalveolar lavage cytokine levels were unchanged in TREK-1-deficient mice compared with controls. Exposure to hyperoxia and mechanical ventilation resulted in an increase in bronchoalveolar lavage interleukin-6, monocyte chemotactic protein-1, and tumor necrosis factor-α levels in both mouse types, but the increase in interleukin-6 and monocyte chemotactic protein-1 levels was less prominent in TREK-1-deficient mice than in controls. Lung tissue macrophage inflammatory protein-2, keratinocyte-derived cytokine, and interleukin-1ß gene expression was not altered by hyperoxia in TREK-1-deficient mice compared with controls. Furthermore, we show for the first time TREK-1 expression on alveolar macrophages and unimpaired tumor necrosis factor-α secretion from TREK-1-deficient macrophages. CONCLUSIONS: TREK-1 deficiency resulted in increased sensitivity of lungs to hyperoxia, but this effect is less prominent if overwhelming injury is induced by the combination of hyperoxia and injurious mechanical ventilation. TREK-1 may constitute a new potential target for the development of novel treatment strategies against hyperoxia-induced lung injury.

Ketamine affects the neurogenesis of rat fetal neural stem progenitor cells via the PI3K/Akt-p27 signaling pathway.

Ketamine is widely used as an anesthetic, analgesic, or sedative in pediatric patients. We reported that ketamine alters the normal neurogenesis of rat fetal neural stem progenitor cells (NSPCs) in the developing brain, but the underlying mechanisms remain unknown. The PI3K-PKB/Akt (phosphatidylinositide 3-kinase/protein kinase B) signaling pathway plays many important roles in cell survival, apoptosis, and proliferation. We hypothesized that PI3K-PKB/Akt signaling may be involved in ketamine-altered neurogenesis of cultured NSPCs in vitro. NSPCs were isolated from Sprague-Dawley rat fetuses on gestational day 17. 5-bromo-2'-deoxyuridine (BrdU) incorporation, Ki67 staining, and differentiation tests were utilized to identify primary cultured NSPCs. Immunofluorescent staining was used to detect Akt expression, whereas Western blots measured phosphorylated Akt and p27 expression in NSPCs exposed to different treatments. We report that cultured NSPCs had properties of neurogenesis: proliferation and neural differentiation. PKB/Akt was expressed in cultured rat fetal cortical NSPCs. Ketamine inhibited the phosphorylation of Akt and further enhanced p27 expression in cultured NSPCs. All ketamine-induced PI3K/Akt signaling changes could be recovered by N-methyl-d-aspartate (NMDA) receptor agonist, NMDA. These data suggest that the inhibition of PI3K/Akt-p27 signaling may be involved in ketamine-induced neurotoxicity in the developing brain, whereas excitatory NMDA receptor activation may reverse these effects.

Early adversity, socioemotional development, and stress in urban 1-year-old children.

OBJECTIVE: To determine demographic, maternal, and child factors associated with socioemotional (SE) problems and chronic stress in 1-year-old children. STUDY DESIGN: This was a prospective, longitudinal, community-based study, which followed mother-infant dyads (n = 1070; representative of race, education, and income status of Memphis/Shelby County, Tennessee) from midgestation into early childhood. Child SE development was measured using the Brief Infant-Toddler Social and Emotional Assessment in all 1097 1-year-olds. Chronic stress was assessed by hair cortisol in a subsample of 1-year-olds (n = 297). Multivariate regression models were developed to predict SE problems and hair cortisol levels. RESULTS: More black mothers than white mothers reported SE problems in their 1-year-olds (32.9% vs 10.2%; P < .001). In multivariate regression, SE problems in blacks were predicted by lower maternal education, greater parenting stress and maternal psychological distress, and higher cyclothymic personality score. In whites, predictors of SE problems were Medicaid insurance, higher maternal depression score at 1 year, greater parenting stress and maternal psychological distress, higher dysthymic personality score, and male sex. SE problem scores were associated with higher hair cortisol levels (P = .01). Blacks had higher hair cortisol levels than whites (P < .001). In the entire subsample, increased hair cortisol levels were associated with higher parenting stress (P = .001), lower maternal depression score (P = .01), lower birth length (P < .001), and greater length at 1 year of age (P = .003). CONCLUSION: Differences in maternal education, insurance, mental health, and early stress may disrupt SE development in children. Complex relationships between hair cortisol level in 1-year-olds and maternal parenting stress and depression symptoms suggest dysregulation of the child's hypothalamic-pituitary-adrenal axis.

Prevalence of burnout and its relation to the neuroendocrine system among pediatric residents during the early Covid-19 pandemic: A pilot feasibility study.

Background: Measuring burnout relies on infrequent and subjective surveys, which often do not reflect the underlying factors or biological mechanisms that promote or prevent it. Burnout correlates with cortisol levels and dysregulation of the hypothalamic-pituitary-adrenal axis, but the chronology and strength of this relationship are unknown. Objective: To determine the prevalence and feasibility of studying burnout in pediatric residents using hair cortisol and hair oxytocin concentrations. Design: /Methods: Longitudinal observational cohort study of pediatric residents. We assessed burnout using the Stanford Professional Fulfillment Index and hair cortisol (HCC), and hair oxytocin concentrations (HOC) at four 3-month intervals from January 2020-January 2021. We evaluated test-retest reliability, sensitivity to change using Pearson product-moment correlations, and relationships between burnout and hair biomarkers using hierarchical mixed-effects linear regression. Results: 17 Pediatrics residents provided 78 wellness surveys and 54 hair samples. Burnout symptoms were present in 39 (50%) of the surveys, with 14 (82%) residents reporting burnout in at least one time point. The lowest (41%) and highest (60%) burnout prevalence occurred in 04/2020 and 01/2021, respectively. No significant associations between burnout scores and HCC (ß -0.01, 95%CI: 0.14-0.13), HOC (ß 0.06, 95%CI: 0.06-0.19), or the HCC:HOC ratio (ß -0.04, 95%CI: 0.09-0.02) were noted in separate analyses. Intra-individual changes in hair cortisol concentration were not associated with changes in burnout score. Conclusions: Burnout was prevalent among Pediatrics residents, with highest prevalence noted in January 2021. This pilot longitudinal study demonstrates the feasibility of evaluating burnout with stress and resilience biomarkers in Pediatrics residents.

Ketamine alters the neurogenesis of rat cortical neural stem progenitor cells.

OBJECTIVE: High doses or prolonged exposure to ketamine increase neuronal apoptosis in the developing brain, although effects on neural stem progenitor cells remain unexplored. This study investigated dose- and time-dependent responses to ketamine on cell death and neurogenesis in cultured rat fetal cortical neural stem progenitor cells. DESIGN: Laboratory-based study. SETTING: University research laboratory. SUBJECT: Sprague-Dawley rats. INTERVENTIONS: Neural stem progenitor cells were isolated from the cortex of Sprague-Dawley rat fetuses on embryonic day 17. In dose-response experiments, cultured neural stem progenitor cells were exposed to different concentrations of ketamine (0-100 µM) for 24 hrs. In time-course experiments, neural stem progenitor cells cultures were exposed to 10 µM ketamine for different durations (0-48 hrs). MEASUREMENTS AND MAIN RESULTS: Apoptosis and necrosis in neural stem progenitor cells were assessed using activated caspase-3 immunostaining and lactate dehydrogenase assays, respectively. Proliferative changes in neural stem progenitor cells were detected using bromo-deoxyuridine incorporation and Ki67 immunostaining. Neuronal differentiation was assessed using Tuj-1 immunostaining. Cultured neural stem progenitor cells were resistant to apoptosis and necrosis following all concentrations and durations of ketamine exposure tested. Ketamine inhibited proliferation with decreased numbers of bromo-deoxyuridine-positive cells following ketamine exposure to 100 µM for 24 hrs (p<.005) or 10 µM for 48 hrs (p< .01), and reduced numbers of Ki67-positive cells following exposure to ketamine concentration>10 µM for 24 hrs (p<.001) or at 10 µM for 48 hrs (p<.01). Ketamine enhanced neuronal differentiation, with all ketamine concentrations increasing Tuj-1-positive neurons (p<.001) after 24-hrs of exposure. This also occurred with all exposures to 10 µM ketamine for >8 hrs (p<.001). CONCLUSIONS: Clinically relevant concentrations of ketamine do not induce cell death in neural stem progenitor cells via apoptosis or necrosis. Ketamine alters the proliferation and increases the neuronal differentiation of neural stem progenitor cells isolated from the rat neocortex. These studies imply that ketamine exposure during fetal or neonatal life may alter neurogenesis and subsequent brain development.

Longitudinal Trajectories of Hair Cortisol: Hypothalamic-Pituitary-Adrenal Axis Dysfunction in Early Childhood.

The objective of this study was to examine if longitudinal trajectories of hair cortisol concentrations (HCC) measured at two or three yearly time points can identify 1-3 year old children at risk for altered hypothalamic-pituitary-adrenal (HPA)-axis function due to early life stress (ELS). HCC was measured (N = 575) in 265 children using a validated enzyme-linked immunosorbent assay. Hair was sampled in Clinic Visits (CV) centered at years 1, 2, and 3 (n = 45); 1 and 2 (n = 98); 1 and 3 (n = 27); 2 and 3 (n = 95). Log-transformed HCC values were partitioned using latent class mixed models (LCMM) to minimize the Bayesian Information Criterion. Multivariable linear mixed effects models for ln-HCC as a function of fixed effects for age in months and random effects for participants (to account for repeated measures) were generated to identify the factors associated with class membership. Children in Class 1 (n = 69; 9% Black) evidenced declining ln-HCC across early childhood, whereas Class 2 members (n = 196; 43% Black) showed mixed trajectories. LCMM with only Class 2 members revealed Class 2A (n = 17, 82% Black) with sustained high ln-HCC and Class 2B (n = 179, 40% Blacks) with mixed ln-HCC profiles. Another LCMM limited to only Class 2B members revealed Class 2B1 (n = 65, 57% Black) with declining ln-HCC values (at higher ranges than Class 1), and Class 2B2 (n = 113, 30% Black) with sustained high ln-HCC values. Class 1 may represent hair cortisol trajectories associated with adaptive HPA-axis profiles, whereas 2A, 2B1, and 2B2 may represent allostatic load with dysregulated profiles of HPA-axis function in response to varying exposures to ELS. Sequential longitudinal hair cortisol measurements revealed the allostatic load associated with ELS and the potential for developing maladaptive or dysregulated HPA-axis function in early childhood.

Historical roots of pain management in infants: A bibliometric analysis using reference publication year spectroscopy.

Retrospective evaluations of the historical role of previously published research are often fraught with subjective bias and misrepresentation, which leads to contested scientific claims. This paper investigates the historical roots of infant pain management using novel quantitative methods to identify the published literature and evaluate its relative importance. A bibliometric analysis named "reference publication year spectroscopy" (RPYS), was performed using the program CitedReferencesExplorer (CRExplorer) to avoid the subjectivity associated with comparative evaluations of individual research studies. Web of Science (WoS) search queries on infant-related synonyms, pain-related synonyms, and analgesia or anesthesia-related synonyms were combined using the Boolean operator "AND," to identify all publications related to pain management in infants. The RPYS analyses were based on 8697 papers in our publication set containing the citations for 86268 references. Selected cited publications were associated with peak citation years in 1951, 1954, 1957, 1965, 1987, 1990, 1997, 1999, and 2000. Subsequent analyses suggested that research on infant pain management made rapid progress during 1982-1992. Landmark publications were defined as those belonging to the top 10% of the most frequently referenced publications for longer than 25 years. Through this analysis, we identified and ranked 24 landmark publications to illustrate the historical background and early research on infant pain management. From the first-ever application of RPYS (an objective, reproducible approach to study the early history of any scholarly activity) to pain research, infant pain management appears rooted in the scientific rationale for neonatal pain perception, randomized trials of opioid anesthesia/analgesia, and studies describing the facial expressions and crying activity following heel-lance procedures in newborns.

The interaction between stress and chronic pain through the lens of threat learning.

Stress and pain are interleaved at multiple levels - interacting and influencing each other. Both are modulated by psychosocial factors including fears, beliefs, and goals, and are served by overlapping neural substrates. One major contributing factor in the development and maintenance of chronic pain is threat learning, with pain as an emotionally-salient threat - or stressor. Here, we argue that threat learning is a central mechanism and contributor, mediating the relationship between stress and chronic pain. We review the state of the art on (mal)adaptive learning in chronic pain, and on effects of stress and particularly cortisol on learning. We then provide a theoretical integration of how stress may affect chronic pain through its effect on threat learning. Prolonged stress, as may be experienced by patients with chronic pain, and its resulting changes in key brain networks modulating stress responses and threat learning, may further exacerbate these impairing effects on threat learning. We provide testable hypotheses and suggestions for how this integration may guide future research and clinical approaches in chronic pain.

Ketamine analgesia for inflammatory pain in neonatal rats: a factorial randomized trial examining long-term effects.

BACKGROUND: Neonatal rats exposed to repetitive inflammatory pain have altered behaviors in young adulthood, partly ameliorated by Ketamine analgesia. We examined the relationships between protein expression, neuronal survival and plasticity in the neonatal rat brain, and correlated these changes with adult cognitive behavior. METHODS: Using Western immunoblot techniques, homogenates of cortical tissue were analyzed from neonatal rats 18-20 hours following repeated exposure to 4% formalin injections (F, N = 9), Ketamine (K, 2.5 mg/kg x 2, N = 9), Ketamine prior to formalin (KF, N = 9), or undisturbed controls (C, N = 9). Brain tissues from another cohort of rat pups (F = 11, K = 12, KF = 10, C = 15) were used for cellular staining with Fos immunohistochemistry or FluoroJade-B (FJB), followed by cell counting in eleven cortical and three hippocampal areas. Long-term cognitive testing using a delayed non-match to sample (DNMS) paradigm in the 8-arm radial maze was performed in adult rats receiving the same treatments (F = 20, K = 24, KF = 21, C = 27) in the neonatal period. RESULTS: Greater cell death occurred in F vs. C, K, KF in parietal and retrosplenial areas, vs. K, KF in piriform, temporal, and occipital areas, vs. C, K in frontal and hindlimb areas. In retrosplenial cortex, less Fos expression occurred in F vs. C, KF. Cell death correlated inversely with Fos expression in piriform, retrosplenial, and occipital areas, but only in F. Cortical expression of glial fibrillary acidic protein (GFAP) was elevated in F, K and KF vs. C. No significant differences occurred in Caspase-3, Bax, and Bcl-2 expression between groups, but cellular changes in cortical areas were significantly correlated with protein expression patterns. Cluster analysis of the frequencies and durations of behaviors grouped them as exploratory, learning, preparatory, consumptive, and foraging behaviors. Neonatal inflammatory pain exposure reduced exploratory behaviors in adult males, learning and preparatory behaviors in females, whereas Ketamine ameliorated these long-term effects. CONCLUSION: Neuroprotective effects of Ketamine attenuate the impaired cognitive behaviors resulting from pain-induced cell death in the cortical and hippocampal fields of neonatal rats. This cell death was not dependent on the apoptosis associated proteins, but was correlated with glial activation.