An EPA database on the effects of engineered nanomaterials-NaKnowBase.

The US EPA Office of Research and Development (ORD) has conducted a research program assessing potential risks of emerging materials and technologies, including engineered nanomaterials (ENM). As a component of that program, a nanomaterial knowledge base, termed "NaKnowBase", was developed containing the results of published ORD research relevant to the potential environmental and biological actions of ENM. The experimental data address issues such as ENM release into the environment; fate, transport and transformations in environmental media; exposure to ecological species or humans; and the potential for effects on those species. The database captures information on the physicochemical properties of ENM tested, assays performed and their parameters, and the results obtained. NaKnowBase (NKB) is a relational SQL database, and may be queried either with SQL code or through a user-friendly web interface. Filtered results may be output in spreadsheet format for subsequent user-defined analyses. Potential uses of the data might include input to quantitative structure-activity relationships (QSAR), meta-analyses, or other investigative approaches.

The carbon partitioning of glucose and DIC in mixotrophic, heterotrophic and photoautotrophic cultures of Tetraselmis suecica.

OBJECTIVE: Changes in the partitioning of dissolved inorganic (DIC) and glucose were elucidated by utilising 13C labelled DIC or glucose, and quantifying the biochemical profile of mixotrophic, heterotrophic and photoautotrophic cultures of the microalga Tetraselmis suecica. RESULTS: Mixotrophic cultivation increases microalgal productivity and changes their biochemical profile, due to an alteration in the partitioning of carbon within the cell. When cultured mixotrophically and heterotrophically, there is enhanced incorporation of carbon into shorter chain saturated fatty acids and non-lipid biomass, compared to photoautotrophic cultivation. Autotrophic culture results in increased total fatty acid content of cultures (4.19% dry weight compared to 2.13%) and shifts the fatty acid profile in favour of long-chain unsaturated fatty acids, such as 18:2 n-(9,12), compared to mixotrophic culture. Quantifying the changes in partitioning between DIC and glucose facilitates tailoring of the biochemical profile to develop "designer" algae. CONCLUSIONS: There is a condition specific shift in carbon partitioning into different fatty acid and biochemical fractions in T. suecica, with more inorganic carbon partitioned into 18:2 n-(9,12) in photoautotrophic rather than mixotrophic cultures.

Defining Risk of Postoperative Obstructive Sleep Apnea in Patients With 22q11.2DS Undergoing Pharyngeal Flap Surgery for Velopharyngeal Dysfunction Using Polysomnographic Evaluation.

OBJECTIVE: To determine pre- and postoperative prevalence of obstructive sleep apnea (OSA) in patients with 22q11.2 deletion syndrome (DS) undergoing wide posterior pharyngeal flap (PPF) surgery for velopharyngeal dysfunction (VPD). DESIGN: Retrospective study using pre- and postoperative polysomnography (PSG) to determine prevalence of OSA. Medical records were reviewed for patients' medical comorbidities. Parents were surveyed about snoring. SETTING: Academic tertiary care pediatric hospital. PATIENTS: Forty patients with laboratory confirmed 22q11.2DS followed over a 6-year period. INTERVENTIONS: Pre- and postoperative PSG, speech evaluation, and parent surveys. MAIN OUTCOME MEASURE: Severity and prevalence of OSA, defined by obstructive apnea hypopnea index (OAHI), before and after PPF surgery to determine whether PPF is associated with increased risk of OSA. RESULTS: Mean OAHI did not change significantly after PPF surgery (1.1/h vs 2.1/h, P = .330). Prevalence of clinically significant OSA (OAHI ≥ 5) was identical pre- and postoperatively (2 of 40), with both cases having severe-range OSA requiring positive airway pressure therapy. All other patients had mild-range OSA. Nasal resonance was graded as severe preoperatively in 85% of patients. None were graded as severe postoperatively. No single patient factor or parent-reported concern predicted risk of OSA (OAHI ≥ 1.5). CONCLUSIONS: Patients with 22q11.2DS are medically complex and are at increased risk of OSA at baseline. Wide PPF surgery for severe VPD does not significantly increase risk of OSA. Careful perioperative planning is essential to optimize both speech and sleep outcomes.

Does Increased Consolidated Nighttime Sleep Facilitate Attentional Control? A Pilot Study of Nap Restriction in Preschoolers.

OBJECTIVE: The aim of this study is to understand the impact of a 5-day period of nap restriction on sleep patterns and cognitive function in typically developing preschoolers, aged 3 to 4 years. METHOD: Following 1 week of baseline assessment, 28 children were randomly assigned to either a "napping as usual" group ( n = 15) or a 5-day period of nap restriction ( n = 13). Sleep was assessed with sleep logs and actigraphy; cognition was assessed at baseline and at the end of the intervention week. RESULTS: No group differences in sleep or cognitive function were observed at baseline. For the no-nap group, the 5-day period of daytime nap restriction resulted in increased nighttime sleep. Children in the no-nap group also showed a significant improvement in attentional control compared with baseline, whereas no such changes were observed among children in the napping-as-usual group. CONCLUSION: In preschool children who typically take naps, short-term nap restriction is associated with increased nighttime sleep and may contribute to improved attentional function.

Pixelated spatial gene expression analysis from tissue.

Here, we present a technique that performs on-chip picoliter real-time reverse transcriptase loop mediated isothermal amplification (RT-LAMP) reactions on a histological tissue section without any analyte purification while preserving the native spatial location of the nucleic acid molecules. We demonstrate this method by amplifying TOP2A messenger RNA (mRNA) in a prostate cancer xenograft with 100 µm spatial resolution and by visualizing the variation in threshold time of amplification across the tissue. The on-chip reaction was validated by mRNA fluorescence in situ hybridization (mFISH) from cells in the tissue section. The entire process, from tissue loading on microchip to results from RT-LAMP can be carried out in less than 2 h. We anticipate that this technique, with its ease of use, fast turnaround, and quantitative molecular outputs, would become an invaluable tissue analysis tool for researchers and clinicians in the biomedical arena.

Kleine-Levin Syndrome.

Kleine-Levin syndrome (KLS) is a rare disorder characterized by discrete episodes of hypersomnia associated with cognitive and behavioural abnormalities, as well as normal alertness and function between episodes. The prevalence of KLS may be underestimated as it is often misdiagnosed and managed as another sleep disorder, neurological disorder or psychiatric condition. KLS is more typically seen in adolescence than at other ages, and is more common in males than in females. There are currently neither standard biomarkers nor specific imaging study findings, making the diagnosis of KLS a challenge. Furthermore, there are no consistently effective therapies. The prognosis, however, is felt to be overall favorable, as episodes become progressively milder and less frequent before resolving entirely in most patients.

Validation of a microdose probe drug cocktail for clinical drug interaction assessments for drug transporters and CYP3A.

A microdose cocktail containing midazolam, dabigatran etexilate, pitavastatin, rosuvastatin, and atorvastatin has been established to allow simultaneous assessment of a perpetrator impact on the most common drug metabolizing enzyme, cytochrome P450 (CYP)3A, and the major transporters organic anion-transporting polypeptides (OATP)1B, breast cancer resistance protein (BCRP), and MDR1 P-glycoprotein (P-gp). The clinical utility of these microdose cocktail probe substrates was qualified by conducting clinical drug interaction studies with three inhibitors with different in vitro inhibitory profiles (rifampin, itraconazole, and clarithromycin). Generally, the pharmacokinetic profiles of the probe substrates, in the absence and presence of the inhibitors, were comparable to their reported corresponding pharmacological doses, and/or in agreement with theoretical expectations. The exception was dabigatran, which resulted in an approximately twofold higher magnitude for microdose compared to conventional dosing, and, thus, can be used to flag a worst-case scenario for P-gp. Broader application of the microdose cocktail will facilitate a more comprehensive understanding of the roles of drug transporters in drug disposition and drug interactions.

Atmospheric benzenoid emissions from plants rival those from fossil fuels.

Despite the known biochemical production of a range of aromatic compounds by plants and the presence of benzenoids in floral scents, the emissions of only a few benzenoid compounds have been reported from the biosphere to the atmosphere. Here, using evidence from measurements at aircraft, ecosystem, tree, branch and leaf scales, with complementary isotopic labeling experiments, we show that vegetation (leaves, flowers, and phytoplankton) emits a wide variety of benzenoid compounds to the atmosphere at substantial rates. Controlled environment experiments show that plants are able to alter their metabolism to produce and release many benzenoids under stress conditions. The functions of these compounds remain unclear but may be related to chemical communication and protection against stress. We estimate the total global secondary organic aerosol potential from biogenic benzenoids to be similar to that from anthropogenic benzenoids (~10 Tg y(-1)), pointing to the importance of these natural emissions in atmospheric physics and chemistry.

Prevalence of periodic limb movements during sleep in normal children.

STUDY OBJECTIVES: Although the American Academy of Sleep Medicine (AASM) mandates that periodic limb movements during sleep (PLMS) be scored on every polysomnogram, and considers a periodic limb movement index (PLMI) > 5/h abnormal in children, there is a lack of community-derived data regarding the prevalence of PLMS in children, and no data to support this cutoff value. Therefore, the aim of this study was to determine the prevalence of PLMS in a sample of normal children. DESIGN: Retrospective study. PARTICIPANTS: 195 healthy, non-snoring children aged 5-17 years, recruited from the community, who underwent polysomnography for research purposes. METHODS: PLMS were scored using the AASM 2007 criteria. MEASUREMENTS AND RESULTS: The group age (median [IQR]) was 12.9 [10-15] years, and 58% were male. Sleep architecture was normal, and the obstructive apnea hypopnea index was 0.1 [0-0.3]/h. The median PLMI was 0/h, ranging from 0 to 35.5/h. Fifteen (7.7%) subjects had a PLMI > 5/h, and only 3 (1.5%) met the adult pathologic criterion of more than 15/h. Use of the 95th percentile PLMI cutoff of 7.2/h produced little difference in categorization between groups. Children with a PLMI > 5/h had a higher arousal index than those with a lower PLMI (11.6 [8.8-14.6] vs 8.1 [6.1-9.9]/h, respectively, P = 0.003). CONCLUSIONS: This study provides normative data to the field and supports the clinical periodic limb movement index cutoff of > 5/h based on both prevalence and the correlate of increased sleep fragmentation. Periodic limb movements during sleep are infrequent in normal children recruited from the community. CITATION: Marcus CL, Traylor J, Gallagher PR, Brooks LJ, Huang J, Koren D, Katz L, Mason TB, Tapia IE. Prevalence of periodic limb movements during sleep in normal children.

22q11.2 Deletion syndrome and obstructive sleep apnea.

UNLABELLED: Otolaryngologic problems are common in the 22q11.2 deletion syndrome (DS) population. Structural anomalies and retrognathia may predispose these patients to obstructive sleep apnea (OSA). The current association of OSA in this population is not defined. OBJECTIVE: (1) Define the frequency of OSA in 22q11.2 DS patients referred for polysomnography (PSG). (2) Determine if OSA is present before and/or after surgery to correct velopharyngeal insufficiency (VPI). (3) Determine effect of prior adenotonsillectomy on OSA following VPI surgery. METHODS: Retrospective review of children treated from 2006 to 2013 in a tertiary care setting identified by ICD-9 758.32 (velocardiofacial syndrome) and 279.11 (DiGeorge syndrome). Surgical history and PSG data were abstracted from the identified records. RESULTS: We identified 323 patients with 22q11.2 DS; 57 (18%) were screened at any point in care using PSG and 15 patients had PSG at multiple time points in care. In most cases, indication for PSG was sleep disordered breathing or pre-operative planning. Overall, 33 patients met criteria for OSA on PSG, accounting for 10.2% of our study population; however, the percentage of patients with OSA was significantly higher within the group of 57 patients (58%) who were screened with PSG. Twenty-one of the screened patients (54%) had PSG prior to any pharyngeal surgery and had mild to severe OSA (obstructive apnea/hypopnea index (AHI): median 5.1/h, range 1.9-25.6). Eighteen patients had PSG after adenotonsillectomy; 8 of these patients (44%) had mild to moderate OSA (median AHI 2.95/h, range 1.9-5.4). Seventeen patients had PSG after VPI surgery (palatopharyngeal flap (PPF) n=16, sphincteroplasty n=1). Nine of these patients (53%) had mild to severe OSA (median AHI 3/h, range 1.9-15). Patients who underwent adenotonsillectomy prior to VPI surgery had similar prevalence of OSA (50%, n=12) than those who did not (OSA: 60%, n=5, p=0.70). Most children had mild OSA. CONCLUSION: Prevalence of OSA in this population of 22q11.2 DS patients is higher than expected in the general population. OSA risk is highest after VPI surgery, and may be decreased by adenotonsillectomy. Providers should have awareness of increased prevalence of OSA in patients with 22q11.2 DS. Close monitoring for OSA is warranted given the likelihood of subsequent surgical intervention that can worsen OSA.

Assessing different mechanisms of toxicity in mountaintop removal/valley fill coal mining-affected watershed samples using Caenorhabditis elegans.

Mountaintop removal-valley fill coal mining has been associated with a variety of impacts on ecosystem and human health, in particular reductions in the biodiversity of receiving streams. However, effluents emerging from valley fills contain a complex mixture of chemicals including metals, metalloids, and salts, and it is not clear which of these are the most important drivers of toxicity. We found that streamwater and sediment samples collected from mine-impacted streams of the Upper Mud River in West Virginia inhibited the growth of the nematode Caenorhabditis elegans. Next, we took advantage of genetic and transgenic tools available in this model organism to test the hypotheses that the toxicity could be attributed to metals, selenium, oxidative stress, or osmotic stress. Our results indicate that in general, the toxicity of streamwater to C. elegans was attributable to osmotic stress, while the toxicity of sediments resulted mostly from metals or metalloids.

Brain tumor presenting as somnambulism in an adolescent.

BACKGROUND: Sleepwalking is typically a benign and self-limited non-rapid eye movement parasomnia of childhood. PATIENT: We describe an unusual 15-year-old boy referred to our sleep center for new-onset sleepwalking. RESULTS: An overnight polysomnogram was normal from a respiratory standpoint, but a concurrent extended electroencephalogram montage showed frequent epileptiform discharges from the right parietal-temporal region and two electroclinical seizures arising from the right-frontal-central-temporal region during sleep. Magnetic resonance imaging scan revealed a right parasagittal parietal region lesion consistent with a low-grade neoplasm, and surgical resection of the lesion demonstrated a right parietal dysembryoplastic neuroepithelial tumor. Complex partial seizures and sleepwalking remitted completely with anticonvulsant therapy following surgery. CONCLUSIONS: This patient highlights the differential diagnosis of nocturnal events appearing to be typical parasomnias, especially when they arise abruptly at an older age.

Respiratory muscle force and lung volume changes in a population of children with sickle cell disease.

Sickle cell disease (SCD) is a disorder known to impact the respiratory system. We sought to identify respiratory muscle force and lung volume relationships in a paediatric SCD population. Thirty-four SCD-SS subjects underwent pulmonary function testing. Height, weight, age, and gender-adjusted percent predicted maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) values were compared to spirometry and lung volumes. Statistical analyses were performed using Pearson's correlation coefficient and paired two-tailed t-test. The mean ± standard deviation (SD) MIP and MEP was 69·6 ± 31·6 cm H2 O and 66·9 ± 22·9 cm H2 O, respectively, and mean ± SD percent predicted MIP (101·3 ± 45·9) exceeded MEP (72·1 ± 26·0) (P = 0·002). MIP correlated with forced vital capacity (FVC; r = 0·51, P = 0·001) and TLC (r = 0·54, P < 0·0001). MEP also correlated with FVC (r = 0·43, P = 0·011) and total lung capacity (TLC; r = 0·42, P = 0·013). Pearson's correlation coefficient testing yielded relationships between MIP and MEP (r = 0·64, P < 0·0001). SCD-SS patients showed correlations between respiratory muscle force and lung volume, and reduced percent predicted expiratory muscle force compared to inspiratory muscle force. Respiratory muscle strength may affect lung volumes in these patients, and expiratory muscles may be more susceptible than the diaphragm to SCD-induced vaso-occlusive damage.

Subtelomeric deletion of chromosome 10p15.3: clinical findings and molecular cytogenetic characterization.

We describe 19 unrelated individuals with submicroscopic deletions involving 10p15.3 characterized by chromosomal microarray (CMA). Interestingly, to our knowledge, only two individuals with isolated, submicroscopic 10p15.3 deletion have been reported to date; however, only limited clinical information is available for these probands and the deleted region has not been molecularly mapped. Comprehensive clinical history was obtained for 12 of the 19 individuals described in this study. Common features among these 12 individuals include: cognitive/behavioral/developmental differences (11/11), speech delay/language disorder (10/10), motor delay (10/10), craniofacial dysmorphism (9/12), hypotonia (7/11), brain anomalies (4/6) and seizures (3/7). Parental studies were performed for nine of the 19 individuals; the 10p15.3 deletion was de novo in seven of the probands, not maternally inherited in one proband and inherited from an apparently affected mother in one proband. Molecular mapping of the 19 individuals reported in this study has identified two genes, ZMYND11 (OMIM 608668) and DIP2C (OMIM 611380; UCSC Genome Browser), mapping within 10p15.3 which are most commonly deleted. Although no single gene has been identified which is deleted in all 19 individuals studied, the deleted region in all but one individual includes ZMYND11 and the deleted region in all but one other individual includes DIP2C. There is not a clearly identifiable phenotypic difference between these two individuals and the size of the deleted region does not generally predict clinical features. Little is currently known about these genes complicating a direct genotype/phenotype correlation at this time. These data however, suggest that ZMYND11 and/or DIP2C haploinsufficiency contributes to the clinical features associated with 10p15 deletions in probands described in this study.

Capturing PLMS and their variability in children with sickle cell disease: does ankle activity monitoring measure up to polysomnography?

OBJECTIVES: To test agreement and define differences in periodic limb movements in sleep (PLMS) measured by polysomnography and an ankle activity monitor, and to describe PLMS variability across nights, feasibility of home monitoring, and correlates of PLMS in children with sickle cell disease (SCD). METHODS: Twenty children with SCD and restless legs syndrome (RLS) symptoms or polysomnography-documented PLMS underwent concurrent attended polysomnography and ankle activity monitoring over one to two nights and home activity monitoring for three nights. Serum iron and ferritin were measured pre- and post-polysomnography. RESULTS: Adequate sensitivity (1.00), specificity (0.69), and mean bias (5.0±7.4 PLMS/h) for identifying elevated PLMS by activity monitor were obtained when scoring the period from sleep onset to offset rather than time in bed per manufacturer recommendation, and using a cut-point of 10 PLMS/h. Compared to activity monitor, only polysomnographic PLMS demonstrated periodicity, at inter-movement intervals (IMI) 20-35 s; the activity monitor overscored PLMS at the beginning and end of sleep and at shorter IMI (5-15s; p≤0.003), suggesting misclassification of nonperiodic leg movements as PLMS by activity monitor. PLMS varied across four nights by 16.1±13.4 PLMS/h. Post-polysomnography ferritin was associated (positively) with PLMS (p=0.034); RLS symptoms were not. CONCLUSIONS: Ankle activity monitoring is a valid screening measure for PLMS in children with SCD and can readily be performed at home. Interpretation should incorporate a threshold for elevated PLMS of 10/h and scoring from sleep onset to offset, which could be identified with concurrent wrist actigraphy, to better account for true PLMS.

Non-invasive measurements of carboxyhemoglobin and methemoglobin in children with sickle cell disease.

Assessment of oxyhemoglobin saturation in patients with sickle cell disease (SCD) is vital for prompt recognition of hypoxemia. The accuracy of pulse oximeter measurements of blood oxygenation in SCD patients is variable, partially due to carboxyhemoglobin (COHb) and methemoglobin (MetHb), which decrease the oxygen content of blood. This study evaluated the accuracy and reliability of a non-invasive pulse co-oximeter in measuring COHb and MetHb percentages (SpCO and SpMet) in children with SCD. We hypothesized that measurements of COHb and MetHb by non-invasive pulse co-oximetry agree within acceptable clinical accuracy with those made by invasive whole blood co-oximetry. Fifty children with SCD-SS underwent pulse co-oximetry and blood co-oximetry while breathing room air. Non-invasive COHb and MetHb readings were compared to the corresponding blood measurements. The pulse co-oximeter bias was 0.1% for COHb and -0.22% for MetHb. The precision of the measured SpCO was ± 2.1% within a COHb range of 0.4-6.1%, and the precision of the measured SpMet was ± 0.33% within a MetHb range of 0.1-1.1%. Non-invasive pulse co-oximetry was useful in measuring COHb and MetHb levels in children with SCD. Although the non-invasive technique slightly overestimated the invasive COHb measurements and slightly underestimated the invasive MetHb measurements, there was close agreement between the two methods.

Upper airway lymphoid tissue size in children with sickle cell disease.

BACKGROUND: The prevalence of obstructive sleep apnea syndrome (OSAS) is higher in children with sickle cell disease (SCD) as compared with the general pediatric population. It has been speculated that overgrowth of the adenoid and tonsils is an important contributor. METHODS: The current study used MRI to evaluate such an association. We studied 36 subjects with SCD (aged 6.9 ± 4.3 years) and 36 control subjects (aged 6.6 ± 3.4 years). RESULTS: Compared with control subjects, children with SCD had a significantly smaller upper airway (2.8 ± 1.2 cm(3) vs 3.7 ± 1.6 cm(3), P < .01), and significantly larger adenoid (8.4 ± 4.1 cm(3) vs 6.0 ± 2.2 cm(3), P < .01), tonsils (7.0 ± 4.3 cm(3) vs 5.1 ± 1.9 cm(3), P < .01), retropharyngeal nodes (3.0 ± 1.9 cm(3) vs 2.2 ± 0.9 cm(3), P < .05), and deep cervical nodes (15.7 ± 5.7 cm(3) vs 12.7 ± 4.0 cm(3), P < .05). Polysomnography showed that 19.4% (seven of 36) of children with SCD had OSAS compared with 0% (zero of 20) of control subjects (P < .05) and that in children with SCD the apnea-hypopnea index correlated positively with upper airway lymphoid tissues size (r = 0.57, P < 001). In addition, children with SCD had lower arterial oxygen saturation nadir (84.3% ± 12.3% vs 91.2% ± 4.2%, P < .05), increased peak end-tidal CO(2) (53.4 ± 8.5 mm Hg vs 42.3 ± 5.3 mm Hg, P < .001), and increased arousals (13.7 ± 4.7 events/h vs 10.8 ± 3.8 events/h, P < .05). CONCLUSIONS: Children with SCD have reduced upper airway size due to overgrowth of the surrounding lymphoid tissues, which may explain their predisposition to OSAS.

Sleep in children with Williams Syndrome.

OBJECTIVE: To analyze sleep in children with Williams Syndrome (WS) compared to normal healthy controls in order to determine whether particular sleep features are characteristic of WS, and to explore associations between disturbed sleep and behavior. METHODS: Thirty-five children with genetically-confirmed WS and 35 matched controls underwent overnight polysomnography and performance testing in the Sleep Center at the Children's Hospital of Philadelphia. Parents completed questionnaires regarding the subjects' sleep and behavior. RESULTS: WS subjects had significantly different sleep than controls, with decreased sleep efficiency, increased respiratory-related arousals and increased slow wave sleep on overnight polysomnography. WS subjects were also noted to have more difficulty falling asleep, with greater restlessness and more arousals from sleep than controls. Fifty-two percent of WS subjects had features of attention deficit-hyperactivity disorder. CONCLUSION: Children with WS had significantly different sleep than controls in our sample. These differences demonstrated in our study may reflect genetic influences on sleep.

Periodic limb movements and disrupted sleep in children with sickle cell disease.

STUDY OBJECTIVES: To describe the rate, distribution and correlates of periodic limb movements in sleep (PLMS) in children with sickle cell disease (SCD). DESIGN: Prospective, cross-sectional. SETTING: Hospital-based sleep laboratory. PARTICIPANTS: Sixty-four children aged 2-18 years with SCD, hemoglobin SS-type who had an overnight polysomnogram and a parent-completed Pediatric Sleep Questionnaire. Mean age was 8.4 years (SD 4.8); 50% were male. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The mean PLMS index was 3.7 (6.6) and ranged from 0 to 31.8, with 23.4% of the sample having PLMS ≥ 5/h. Sleep efficiency was decreased (P = 0.03), and the total arousal index (P = 0.003) and PLMS arousal index (P < 0.001) were increased in children with PLMS ≥ 5/h compared to those with PLMS < 5/h. PLMS were most frequent in NREM stage 2 sleep and during the fourth hour of sleep. Inter-movement interval duration peaked at 25-30 s. "Growing pains worst in bed" or "restlessness of the legs", suggesting restless legs syndrome (RLS), were reported in 12.5% of the total sample and were more common in children with elevated PLMS. A PLMS score for identifying elevated PLMS in children, based on items from the Pediatric Sleep Questionnaire, did not significantly predict PLMS ≥ 5/h. CONCLUSIONS: Elevated PLMS are common in children with SCD and are associated with sleep disruption and symptoms of RLS. Future research into the time structure of PLMS, their causes and consequences, and development of a disease-specific sleep disorders screening questionnaire, is needed in children with SCD.

Defining the roles of actigraphy and parent logs for assessing sleep variables in preschool children.

Actigraphy provides a non-invasive objective means to assess sleep-wake cycles. In young children, parent logs can also be useful for obtaining sleep-wake information. The authors hypothesized that actigraphy and parent logs were both equally valid instruments in healthy preschool-aged children. The authors studied 59 children aged 3 to 5 years in full-time day care. Each child was screened for medical problems and developmental delays before being fitted with an actigraphy watch, which was worn for 1 week. Parents maintained logs of sleep and wakefulness during the same period, with input from day care workers. In general, parents overestimated the amount of nighttime sleep measured by actigraphy by 13% to 22% (all significant). Although there was no difference in sleep onset times, parents reported later rise times on the weekend and fewer nighttime awakenings. There was no significant difference between parent logs and actigraphy with regard to daytime napping. The authors conclude that parent logs are best utilized in assessing daytime sleep and sleep onset, whereas actigraphy should be used to assess nighttime sleep and sleep offset time.