Latency Antibiotics in Preterm Prelabor Rupture of Membranes: A Comparison of Azithromycin Regimens.

BACKGROUND: Treatment with antibiotics at the time of preterm prelabor rupture of membranes (PPROM) has been shown to prolong pregnancy. Due to the recurrent shortage of erythromycin, azithromycin has been substituted in the traditional regimen; however, there are little data on optimal dosing. OBJECTIVE: The objective of this study was to determine whether there is a difference in latency from onset of PPROM to delivery in patients who received a single dose of azithromycin compared with a 5-day course. METHODS: This was a single-center, multisite, retrospective, IRB approved analysis of patients admitted with a diagnosis of PPROM. Patients were included if rupture occurred between 22 0/7 and 33 6/7 weeks of gestation and received either a single dose or a 5-day course of azithromycin along with a beta lactam. RESULTS: A total of 376 patients were reviewed with 296 patients included in the final analysis. There was no statistical difference in the primary outcome of latency days in patients who received the 5-day versus the single-dose course (4 vs 5 days, P = 0.641). There was a significantly higher rate of histologic chorioamnionitis in the single-dose course of azithromycin (46.4% vs 62.6%, P = 0.006). CONCLUSIONS AND RELEVANCE: There was no difference in latency for patients who received a 5-day course of azithromycin versus a single dose for the treatment of PPROM. A higher rate of histologic chorioamnionitis was observed in those who received the single-day course. Prospective follow-up studies are needed to confirm these findings.

Maternal behaviors in toddlerhood as predictors of children's private speech in preschool.

Private speech is an important strategy reflecting children's self-regulation, and thus understanding how parenting may support private speech can inform intervention work on improving self-regulation. The current study longitudinally investigated how sensitive parenting and directive parenting in toddlerhood interacted to predict preschoolers' private speech in an emotion-eliciting task. In toddlerhood, maternal parenting behaviors were observed during two freeplay sessions. Preschoolers' social and private speech were transcribed and coded during a frustration task. Whereas parenting did not relate to other forms of private speech, preschoolers' facilitative task-relevant private speech was predicted by the interaction of mothers' sensitive and directive behaviors. When sensitivity was high, parents who were less directive had children who used more facilitative task-relevant private speech. These findings highlight that children's regulation may be supported through the combination of high sensitivity and low directiveness when parents and children are engaged in unstructured play together.

Inhibitory control in typically developing preschoolers: Relations among temperament, respiratory sinus arrhythmia, and behavior at age 4.

Although inhibitory control (IC) is associated with children's positive adjustment, we know relatively little about factors underlying its development. We examined whether baseline and on-task respiratory sinus arrhythmia [(RSA); a physiological measure of self-regulation] and private speech (a behavioral measure of self-regulation) interacted to confer differences on directly observed IC in 52 typically developing 4-year olds. We found that baseline RSA moderated the association between private speech and IC, such that private speech positively predicted IC in children with relatively higher baseline RSA, but was unrelated to IC in children with relatively lower RSA. We also found that children with a concordant physiological-behavioral pattern (i.e., high RSA and high private speech; low RSA and low private speech) had higher IC, higher effortful control, and lower negative emotionality than those with a discordant physiological-behavioral pattern (i.e., high RSA and low private speech; low RSA and high private speech). Individual differences in physiological and behavioral self-regulation indices may represent distinct regulation pathways that interact to confer differences in IC during the preschool years.

Personality Development Within a Generational Context: Life Course Outcomes of Shy Children.

Studies have shown that shy children born in the 1920s and 1950s had delayed marriage and parenthood, less stable careers, and lower occupational attainment as adults than other children. Do these effects still hold true? We examined demographic and social outcomes of children born between 1977 and 1982 in a prospective longitudinal study. We assessed shyness in childhood (age 8), adolescence (age 12-16), young adulthood (age 22-26), and adulthood (age 30-35), and derived three shyness trajectories (i.e., decreasing, increasing, and low-stable). Social and demographic outcomes for shy children who outgrew their shyness (i.e., decreasing trajectory) were indistinguishable from those who were consistently low on shyness measures. However, a shyness trajectory beginning in adolescence and increasing to adulthood was associated with poorer outcomes, similar to previous studies. These findings highlight the importance of multiple assessments in long-term longitudinal studies and the need to consider personality development within a generational context.

Infant frontal electroencephalogram asymmetry and negative emotional reactivity as predictors of toddlerhood effortful control.

Given the importance of children's self-regulation, relations were examined between two fundamental components of self-regulation, specifically temperamentally based reactivity and regulation. Infant negative emotional reactivity and regulation, measured via frontal electroencephalogram (EEG) asymmetry, were examined as potential precursors to understanding toddlerhood regulation, conceptualized as effortful control. Our longitudinal design allowed for examination of two perspectives on the interplay of reactivity and regulation, namely that (a) early negative affectivity interferes with the development of later regulation and (b) regulation is necessary to modulate negative affectivity and, thus, would buffer the effects of negative affectivity on later regulation. Mother-child dyads participated in a three-wave longitudinal study. Baseline frontal EEG asymmetry was assessed at 10months (T1). Mothers rated children's negative reactivity at both 10 and 24months (T2). Children's effortful control, measured at 30-36months (T3), was a composite score of maternal ratings and observed behavior during a snack delay. Negative affectivity was related to effortful control; however, significant interactions between negative affect and frontal EEG asymmetry were found. Higher levels of negative affectivity at both T1 and T2 were associated with lower levels of effortful control at T3, but only for toddlers who also had right frontal EEG asymmetry. Negative affectivity was not associated with effortful control for the left frontal EEG asymmetry group. Our moderation findings highlight the complex relations of negative affect and frontal EEG asymmetry in understanding children's development of self-regulation, specifically effortful control. The interaction between early reactivity and physiological regulation indicates that both may be important precursors of effortful control.

Database choices in endocrine systematic reviews.

OBJECTIVE: The choice of bibliographic database during the systematic review search process has been an ongoing conversation among information specialists. With newer information sources, such as Google Scholar and clinical trials registries, we were interested in which databases were utilized by information specialists and systematic review researchers. METHOD: We retrieved 144 systematic reviews and meta-analyses from 4 clinical endocrinology journals and extracted all information sources used during the search processes. RESULTS: Findings indicate that traditional bibliographic databases are most often used, followed by regional databases, clinical trials registries, and gray literature databases. CONCLUSIONS: This study informs information specialists about additional resources that may be considered during the search process.

10-year results following impaction bone grafting of major bone defects in 29 rotational and hinged knee revision arthroplasties: a follow-up of a previous report.

BACKGROUND AND PURPOSE: Substantial bone loss in revision total knee arthroplasty (TKA) is a challenging problem. We studied whether impaction bone grafting provides long-term restoration of bone stock in the treatment of major bone defects in revision surgery of rotational and hinged knee arthroplasties (LINK Endo-Model). PATIENTS AND METHODS: Between 1996 and 2006, 29 knees in 29 patients underwent revision procedures of rotational and hinged knee arthroplasties using impaction bone grafting (IBG) to reconstruct major bone defects. At the latest follow-up, the clinical examination included the Knee Society score (KSS), standardized radiographs, and a questionnaire for the WOMAC score. RESULTS: After a mean follow-up of 10 (6-13) years, 14 knees with 19 IBG reconstructions (5 total, 9 partial revisions) had failed. 12 knees were treated with re-revision surgery mean 5 (1-12) years after the first revision, due to mechanical failure and aseptic loosening of the components. In all these failed cases, the surgeon observed a lack of incorporation with bone graft resorption in the femur or tibia during the re-revision procedure. In all 15 knees that were not re-revised, with 21 reconstructions (6 total, 9 partial revisions), an improvement in the combined KSS score (knee score + function score) of 60 points (p < 0.001) was found at the latest follow-up. In 12 of these knees, a clear incorporation with no visible radiolucent lines around the component and no sign of substantial graft resorption was noted, while unclear radiographic graft incorporation was seen in 3 knees. INTERPRETATION: Our results clearly indicate that IBG alone is not a methodologically sound technique in the revision of rotational and hinged knee arthroplasties.

Effects of simulated downwind coal combustion emissions on pre-existing allergic airway responses in mice.

CONTEXT: Coal-fired power plant emissions can contribute a significant portion of the ambient air pollution in many parts of the world. OBJECTIVE: We hypothesized that exposure to simulated downwind coal combustion emissions (SDCCE) may exacerbate pre-existing allergic airway responses. METHODS: Mice were sensitized and challenged with ovalbumin (OVA). Parallel groups were sham-sensitized with saline. Mice were exposed 6 h/day for 3 days to air (control, C) or SDCCE containing particulate matter (PM) at low (L; 100 µg/m³), medium (M; 300 µg/m³), or high (H; 1000 µg/m³) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after SDCCE exposure, mice received another OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air/SDCCE. Measurement of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed ~24 h after the last exposure. RESULTS: SDCCE significantly increased BAL macrophages and eosinophils in OVA-sensitized mice from the post-OVA protocol. However, there was no effect of SDCCE on BAL macrophages or eosinophils in OVA-sensitized mice from the pre-OVA protocol. BAL neutrophils were elevated following SDCCE in both protocols in nonsensitized mice. These changes were not altered by filtering out the PM. In the post-OVA protocol, SDCCE decreased OVA-specific IgG1 in OVA-sensitized mice but increased levels of total IgE, OVA-specific IgE and OVA-specific IgG1 and IgG(2a) in non-sensitized animals. In the pre-OVA protocol, SDCCE increased OVA-specific IgE in both sensitized and non-sensitized animals. Additionally, BAL IL-4, IL-13, and IFN-γ levels were elevated in sensitized mice. CONCLUSION: These results suggest that acute exposure to either the particulate or gaseous phase of SDCCE can exacerbate various features of allergic airway responses depending on the timing of exposure in relation to allergen challenge.

Shyness, Self-regulation, and Cognitive Problem Solving in Typically Developing 4-year-olds: A Pilot Study.

Because shy children are at risk for poor academic achievement, it is important to examine factors that contribute to variability in the relation between individual differences in shyness and cognitive functioning before school entry. The authors examined whether on-task facilitative private speech-a proxy of self-regulation-moderated the association between individual differences in shyness and performance on an executive function (EF) task in 52 typically developing 4-year-olds. They found that private speech interacted with shyness to predict performance on the EF task in girls but not in boys. More specifically, shyness was inversely related to EF task performance when girls used low amounts of regulatory private speech, but was positively related to performance when girls used high amounts of regulatory private speech. These preliminary findings are discussed in the context of implications for shy children in educational settings.

Effects of gasoline engine emissions on preexisting allergic airway responses in mice.

Gasoline-powered vehicle emissions contribute significantly to ambient air pollution. We hypothesized that exposure to gasoline engine emissions (GEE) may exacerbate preexisting allergic airway responses. Male BALB/c mice were sensitized by injection with ovalbumin (OVA) and then received a 10-min aerosolized OVA challenge. Parallel groups were sham-sensitized with saline. Mice were exposed 6 h/day to air (control, C) or GEE containing particulate matter (PM) at low (L), medium (M), or high (H) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after GEE exposure mice received another 10-min aerosol OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air or GEE exposure. Measurements of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed approximately 24 h after the last exposure. In both protocols, M, H, and HF GEE exposure significantly decreased BAL neutrophils from nonsensitized mice but had no significant effect on BAL cells from OVA-sensitized mice. In the pre-OVA protocol, GEE exposure increased OVA-specific IgG(1) but had no effect on BAL interleukin (IL)-2, IL-4, IL-13, or interferon (IFN)-gamma in OVA-sensitized mice. Nonsensitized GEE-exposed mice had increased OVA-specific IgG(2a), IgE, and IL-2, but decreased total IgE. In the post-OVA protocol, GEE exposure reduced BAL IL-4, IL-5, and IFN-gamma in nonsensitized mice but had no effect on sensitized mice. These results suggest acute exposure to the gas-vapor phase of GEE suppressed inflammatory cells and cytokines from nonsensitized mice but did not substantially exacerbate allergic responses.

Patterns of parental emotion-related discourse and links with children's problem behaviors: A person-centered approach.

Research demonstrates that parents' emotion-related discourse during reminiscing shapes children's psychosocial outcomes, yet little is known about how different forms of parental emotion-related discourse work in combination. The present study takes a person-centered approach to better understand the relation of multiple forms of parental emotion discourse during reminiscing with problem behaviors in early childhood, as well as child influences on parents' emotion discourse during reminiscing. Specifically, we simultaneously examine three forms of parents' emotion-related discourse (emotion coaching and dismissing, emotion explanations, and elaboration) using cluster analysis to determine parents' patterns of these three discourse forms during discussion about past events. Parents and their preschool-aged children (n = 154) completed a parent-child reminiscing task. Transcripts were coded for emotion coaching and dismissing, emotion explanations, and elaboration. Parents reported on children's internalizing and externalizing behaviors, temperament, and gender, and children completed a language assessment. Cluster analyses revealed three parental discourse patterns: elaboration/negative emotion emphasis, positive and negative emotion emphasis, and low emotion discourse. Children's receptive language was associated with parents' membership in the low emotion discourse cluster. Children's temperament and gender were unrelated to parental emotion-related discourse patterns. Parents in the positive and negative emotion emphasis cluster had children with fewer internalizing behaviors compared to both other clusters, and parents in the elaboration/negative emotion emphasis cluster had children with more internalizing behaviors compared to both other clusters. Findings support the utility of a person-centered approach in providing a holistic view of parents' use of multiple emotion socialization strategies during reminiscing. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Overprotective Parenting and Peer Victimization in Extremely Low Birth Weight Survivors.

Extremely low birth weight (ELBW; <1000g) survivors are at increased risk for experiencing both peer victimization and overprotective parenting. This study investigated if overprotective parenting moderated associations between peer victimization and psychopathology among ELBW adult survivors who have been followed since birth. Participants included 81 (31 male, 50 female) adults born with an extremely low birth weight from Ontario, Canada. The participants were predominately Caucasian. The experience of peer victimization and overprotective parenting prior to age 16 was self-reported at age 22-26 years. Peer victimization was reported using the Childhood Experiences of Violence Questionnaire and overprotective parenting was reported using the Parental Bonding Instrument. Current anxiety disorder and alcohol or substance use disorder was assessed using the MINI International Neuropsychiatric Interview at age 29-36 years. The experience of overprotective parenting moderated the association between peer victimization and risk for an anxiety disorder in adulthood (OR=2.35, 95%CI, 1.01-5.50). If the ELBW survivor reported having an overprotective parent, peer victimization was associated with increased risk for having an anxiety disorder in adulthood (OR=2.45, 95%CI, 1.13-5.30). In contrast, this association was not significant in the absence of an overprotective parent (OR=1.04, 95%CI, 0.73-1.49). Future research should further investigate if parental support and encouragement of children's independence may be important for reducing the negative effects of peer victimization among ELBW survivors.

Long-term effects of peer victimization on social outcomes through the fourth decade of life in individuals born at normal or extremely low birthweight.

Exposure to early adversity is known to have deleterious effects on brain-behaviour relations across the lifespan and across a range of domains. Here, we tested a cumulative risk hypothesis of adult social functioning and health outcomes in the fourth decade of life, using the oldest known longitudinally followed cohort of survivors of extremely low birthweight (ELBW; <1,000 g). We investigated the additional impact of peer victimization in youth on social outcomes at age 29-36 years in ELBW survivors and matched normal birthweight (NBW; >2,500 g) participants. In the combined sample, peer victimization was associated with lower likelihood of having children and household income, poorer family functioning and self-esteem, more loneliness and chronic health conditions, less social support, and increased likelihood for contact with police. Moderation analyses indicated that among ELBW survivors, compared to their NBW counterparts, victimization was more strongly associated with being convicted of a crime and with having chronic health conditions. These findings highlight the negative long-term impact of peer victimization on all children and that some outcomes may be differentially affected by prenatal and early post-natal environments. Statement of contribution What is already known on this subject Exposure to early adversity has deleterious effects on brain-behaviour relations across the lifespan. Extremely premature children have higher rates of exposure to adversities, including peer victimization. Peer victimization is associated with adverse outcomes in adulthood in those born at term. What does this study add? Victimization negatively impacts the social outcomes of those born extremely premature and at term into adulthood. Associations appear to be affected by individual differences in prenatal and early post-natal environments. Intervention is crucial when peer victimization occurs in children at risk, as well as those typically developing.

Long-term Psychiatric Impact of Peer Victimization in Adults Born at Extremely Low Birth Weight.

BACKGROUND: While children born at extremely low birth weight (ELBW; <1000 g) are at elevated risk for peer victimization, no research has examined its effects on mental health in adulthood. METHODS: ELBW survivors and matched normal birth weight (NBW; >2500 g) controls were part of a prospective, population-based study in Ontario, Canada. Peer victimization before age 16 was self-reported at age 22 to 26 years by using a 10-point measure. Presence of psychiatric disorders was examined at age 22 to 26 years (ELBW n = 142, NBW n = 133) and age 29 to 36 years (ELBW n = 84, NBW n = 90). RESULTS: After adjustment for confounding variables, for each 1-point increase in the peer victimization score, ELBW survivors had increased odds of current depressive (odds ratio [OR] = 1.67, 95% confidence interval [CI], 1.23-2.28), anxiety (OR = 1.36, 95% CI, 1.05-1.76), avoidant (OR = 1.39, 95% CI, 1.08-1.79), antisocial (OR = 1.92, 95% CI, 1.06-2.87), and attention-deficit/hyperactivity (OR = 1.39, 95% CI, 1.06-1.83) problems at age 22 to 26 years. At age 29 to 36 years, peer victimization score predicted increased odds of current panic disorder (OR = 1.69, 95% CI, 1.01-2.83) and obsessive-compulsive disorder (OR = 3.56, 95% CI, 1.25-10.09). For NBW controls, peer victimization predicted increased odds of antisocial problems at age 22 to 26 years. CONCLUSIONS: ELBW survivorsand NBW participants are vulnerable to the adverse psychiatric effects of childhood peer victimization in adulthood.

Adult mental health outcomes of child sexual abuse survivors born at extremely low birth weight.

The high prevalence of child sexual abuse (CSA) is concerning, particularly as survivors are at increased risk for multiple adverse outcomes, including poor mental health across the lifespan. Children born at an extremely low birth weight (ELBW; <1000g) and who experience CSA may be a group that is especially vulnerable to psychopathology later in life. However, no research has considered the mental health risks associated with being born at ELBW and experiencing CSA. In this study, we investigated the mental health of 179 ELBW survivors and 145 matched normal birth weight (NBW; >2500g) participants at ages 22-26 and 29-36. At age 22-26, CSA was associated with increased odds of clinically significant internalizing (OR=7.32, 95% CI: 2.31-23.23) and externalizing (OR=4.65, 95% CI: 1.11-19.51) problems among ELBW participants exposed to CSA compared to those who did not, though confidence intervals were wide. At age 29-36, CSA was linked to increased odds of any current (OR=3.43, 95% CI: 1.08-10.87) and lifetime (OR=7.09, 95% CI: 2.00-25.03) non-substance use psychiatric disorders, however, this did not hold after adjustment for covariates. Statistically significant differences in mental health outcomes were not observed in NBW participants exposed to CSA compared to NBW participants who were not exposed. Survivors of significant perinatal adversity who are also exposed to CSA may be at higher risk for psychopathology through the fourth decade of life.

Health, Wealth, Social Integration, and Sexuality of Extremely Low-Birth-Weight Prematurely Born Adults in the Fourth Decade of Life.

IMPORTANCE: Although it has been previously reported that the transition of extremely low-birth-weight survivors (≤1000 g) in their mid-20s was similar to that of normal-birth-weight controls (>2500g), there was uncertainty as to whether this positive pattern would persist. OBJECTIVE: To compare the social functioning of low-birth-weight prematurely born adults aged 29 to 36 years with that of normal-birth-weight term controls. DESIGN, SETTING, AND PARTICIPANTS: A population-based longitudinal cohort study was conducted in Ontario, Canada, between March 14, 2011, and August 13, 2013, among 100 of 165 low-birth-weight survivors (60.6%) prematurely born between January 1, 1977, and December 31, 1982, and 89 of 144 sociodemographically matched normal-birth-weight term controls (61.8%) recruited at age 8 years. Neurologic impairments were present in 20 premature participants (20.0%). EXPOSURES: Extremely low birth weight. MAIN OUTCOMES AND MEASURES: Information on health, educational level, employment, social integration, sexuality, and reproduction was obtained through standardized questionnaires completed by the participants. RESULTS: Participants included 100 (39 males) extremely low-birth-weight survivors and 89 (33 males) normal-birth-weight term controls. The groups did not differ in the highest educational level achieved or in family and partner relationships. However, a lower proportion of premature adults was employed (odds ratio [OR], 0.37; 95% CI, 0.15 to 0.93) and fewer were employed full time (OR, 0.49; 95% CI, 0.24 to 0.98). The premature group had a mean total personal income of $20 000 less than controls, and more required social assistance (OR, 4.16; 95% CI, 1.13 to 15.33). Compared with the control group, more members of the premature group remained single (OR, 1.95; 95% CI, 1.08 to 3.50), had never had sexual intercourse (OR, 11.30; 95% CI, 2.56 to 49.91), did not have children (OR, 0.52; 95% CI, 0.27 to 0.99), reported more chronic health conditions (ß, 1.54; 95% CI, 0.79 to 2.30), had lower self-esteem (ß, 8.40; 95% CI, 1.68 to 15.12), and were less likely to have current drug abuse or dependence (OR, 0.29; 95% CI, 0.90 to 0.92) or lifetime alcohol abuse or dependence (OR, 0.30; 95% CI, 0.15 to 0.59). A higher proportion of premature adults without neurosensory impairments identified themselves as nonheterosexual (OR, 4.87; 95% CI, 1.01 to 23.69). After exclusion of individuals with neurosensory impairments, differences in employment, social assistance, marital status, and reproduction were no longer significant. CONCLUSIONS AND RELEVANCE: In the fourth decade of life, extremely low-birth-weight survivors achieved similar educational levels and family and partner relationships, and reported fewer risky behaviors compared with controls. However, they had lower levels of employment, income, and self-esteem, and fewer were married and had children. It is therefore essential that these individuals receive necessary support and continued monitoring throughout life.

Peer Victimization in Extremely Low Birth Weight Survivors.

BACKGROUND: Extremely low birth weight (ELBW; <1000 g) children may be at risk for experiencing peer victimization. We examined retrospectively reported peer victimization in ELBW and control children in the oldest known, prospectively followed, population-based birth cohort of ELBW survivors. METHOD: We compared levels of verbal and physical peer victimization in ELBW and control children. We also predicted peer victimization in the ELBW sample from child characteristics. RESULTS: ELBW children, especially girls, were at an increased risk for verbal, but not physical victimization. In addition, ELBW children with a higher IQ reported higher levels of verbal victimization, although ELBW females who had a lower body mass index in childhood reported higher levels of physical victimization. CONCLUSION: Findings highlight the need for parents and clinicians to be aware that ELBW girls, especially those with a lower body mass index in childhood, may be at increased risk of peer victimization, as are ELBW children with a higher IQ.

Intrapelvic dislocation of a femoral trial head during primary total hip arthroplasty requiring laparotomy for retrieval.

BACKGROUND AND PURPOSE: Total hip arthroplasty (THA) is a safe and reliable surgical procedure. However, THA also has intra- and postoperative complications. A dreaded and frustrating intraoperative complication during total hip arthroplasty is dislocation of the femoral trial head from the neck into the pelvis. METHODS: Here, we report on the case of a 71-year old female patient with osteoarthritis of the left hip. Total hip arthroplasty was performed in a lateral position through a standard posterior approach. During intraoperative trial reduction, the femoral trial head dissociated from the taper and dislocated into the psoas compartment. Several unsuccessful attempts, including an additional ventral approach, were made to immediately retrieve the femoral trial head. RESULTS AND INTERPRETATION: Postoperative a Computerized Tomography (CT) was performed to locate the trial head, a secondary explorative laparotomy was undertaken to retrieve it. The retrieval of the femoral trial head should be performed in a planned second surgical procedure to avoid possible complications during the manipulation necessary for retrieval.

Age-specific pulmonary cytochrome P-450 3A1 expression in postnatal and adult rats.

A major cause of death and illness in children under the age of five, most living in polluted cities, is respiratory disease. Previous studies have shown that neonatal animals are more susceptible to bioactivated pulmonary cytotoxicants than adults, despite lower expression of the pulmonary cytochrome P-450s (CYP450s) thought to be involved in bioactivation. One CYP450 that is well documented in the bioactivation of many drugs and environmental toxicants in adult lung, but whose expression has not been evaluated during postnatal pulmonary development, is CYP450 3A (CYP3A). We compared age-specific expression of CYP3A1 in 7-day-old and adult male Sprague-Dawley rats. Unlike those shown for previously studied pulmonary CYP450s, expression levels for CYP3A1 mRNA in differentiating airway cells of postnatal rats are the same as in fully differentiated airway cells of adults. CYP3A1 protein expression (28%) and enzymatic activity (23%) were lower in postnatal airways compared with adults. Although other CYP450 immunoreactive proteins are primarily expressed in nonciliated cells, immunoreactive CYP3A1 protein was expressed in both ciliated and nonciliated cells in postnatal and adult rat proximal airways. CYP3A1 protein is detected diffusely throughout ciliated and nonciliated cells in 7-day-old rats, whereas it is only detected in the apex of these cells in adult rats. This study demonstrates that the lungs of postnatal rats have detectable levels of CYP3A1 and that CYP3A1 mRNA expression appears not to be age dependent, whereas steady-state CYP3A1 protein levels and enzyme activity show an age-dependent pattern.