The functional relationship between yawning and vigilance

BACKGROUND: Although yawning is a ubiquitous and phylogenetically old phenomenon, its origin and purpose remain unclear. The study aimed at testing the widely held hypothesis that yawning is triggered by drowsiness and brings about a reversal or suspension of the process of falling asleep. METHODS: Subjects complaining of excessive sleepiness were spontaneously yawning while trying to stay awake in a quiet and darkened room. Changes in their electroencephalogram (EEG) and heart rate variability (HRV) associated with yawning were compared to changes associated with isolated voluntary body movements. Special care was taken to remove eye blink- and movement-artefacts from the recorded signals. RESULTS: Yawns were preceded and followed by a significantly greater delta activity in EEG than movements (p< or =0.008). After yawning, alpha rhythms were attenuated, decelerated, and shifted towards central brain regions (p< or =0.01), whereas after movements, they were attenuated and accelerated (p<0.02). A significant transient increase of HRV occurred after the onset of yawning and movements, which was followed by a significant slow decrease peaking 17s after onset (p<0.0001). No difference in HRV changes was found between yawns and movements. CONCLUSIONS: Yawning occurred during periods with increased drowsiness and sleep pressure, but was not followed by a measurable increase of the arousal level of the brain. It was neither triggered nor followed by a specific autonomic activation. Our results therefore confirm that yawns occur due to sleepiness, but do not provide evidence for an arousing effect of yawning.

Isolated extraordinary daytime urinary frequency of childhood: a case series of 26 children in Switzerland

BACKGROUND: The term 'isolated extraordinary daytime urinary frequency' designates an abnormally increased diurnal frequency of painless urination in a completely toilet-trained child with normal urinalysis. METHODS: We report the history of 26 children (16 boys and 10 girls; aged between 4.1 and 10 years) who were referred to us between 2002 and 2006 and subsequently diagnosed with this condition. RESULTS: Possible psychosocial problems, or recent emotional stressors, were disclosed in the majority of the children: recent (36 months or less) asylum seekers (n = 9), school-related problems (n = 4), parental divorce (n = 2) or death of the mother (n = 1). Possible dietary causes were observed in 9 patients: oxalate-rich beverages (n = 5) and liberal ingestion of 'acidic' juices (n = 4). A diet low in oxalates was recommended when children were consuming large quantities of oxalate-rich beverages; and a diet low in acidic juice was recommended in those liberally ingesting acidic juices. Reassurance and observation were the approach in the remaining cases. The median duration of the symptoms was 5 months. A longer (p < 0.05) duration was noted in children of asylum seekers. CONCLUSIONS: This functional condition is easily identifiable, but often under- or misdiagnosed. Confounding the condition might result in redundant investigation.

Femoral morphology differs between deficient and excessive acetabular coverage

Structural deformities of the femoral head occurring during skeletal development (eg, Legg-Calvé-Perthes disease) are associated with individual shapes of the acetabulum but it is unclear whether differences in acetabular shape are associated with differences in proximal femoral shape. We questioned whether the amount of acetabular coverage influences femoral morphology. We retrospectively compared the proximal femoral anatomy of 50 selected patients (50 hips) with developmental dysplasia of the hip (lateral center-edge angle [LCE] < or = 25 degrees ; acetabular index > or = 14 degrees ) with 45 selected patients (50 hips) with a deep acetabulum (LCE > or = 39 degrees ). Using MRI arthrography we measured head sphericity, epiphyseal shape, epiphyseal extension, and femoral head-neck offset. A deep acetabulum was associated with a more spherical head shape, increased epiphyseal height with a pronounced extension of the epiphysis towards the femoral neck, and an increased offset. In contrast, dysplastic hips showed an elliptical femoral head, decreased epiphyseal height with a less pronounced extension of the epiphysis, and decreased head-neck offset. Hips with different acetabular coverage are associated with different proximal femoral anatomy. A nonspherical head in dysplastic hips could lead to joint incongruity after an acetabular reorientation procedure. LEVEL OF EVIDENCE: Level IV, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

Vaginal voiding: a common cause of daytime urinary leakage in girls

STUDY OBJECTIVE: To estimate the frequency of vaginal voiding as the cause of daytime urinary leakage in girls, and to study the effect of instructions intended to alleviate the problem. SETTING: Girls with vaginal voiding were identified in a group of girls referred because of daytime urinary leakage. They were evaluated by a noninvasive screening protocol. Girls with vaginal voiding were instructed on how to achieve better toilet habits. PARTICIPANTS: Twelve girls with vaginal voiding. RESULTS: Vaginal voiding was found in 12 of 39 girls with daytime urinary leakage. Their age ranged between 8.5 and 13.9 years. They all had history of small leakage immediately after voiding. A body mass index greater than the corresponding 85th percentile was noted in 5 girls, and labial fusion was noted in 2 girls. The complaint disappeared in 10 girls and improved in the remaining 2 girls after instructions on how to achieve better toilet habits. CONCLUSIONS: Vaginal voiding is common in girls. It occurs in girls at risk of overweight, in girls with labial fusion, and in girls adopting a hairpin posture while sitting on the toilet. The diagnosis is obtained by an adequate history. Proper voiding instructions resolve the problem.

Sleepiness and vigilance tests

Objective assessments of subjective complaints such as sleepiness, tiredness or fatigue using sleepiness and vigilance tests aim to identify its causes and to judge the fitness to drive or to work of the affected person. "Vigilance" comprises wakefulness, alertness and attention and is therefore not merely reciprocal to sleepiness. Since it is a complex phenomenon with several dimensions it is unlikely to be appropriately assessed by one single "vigilance test". One important dimension of vigilance discussed here is wakefulness with its counterpart of overt sleep and the whole spectrum of various levels in between. The transit zone between full wakefulness and overt sleep is mainly characterised by the subjective complaint of sleepiness, which cannot be measured directly. Only the consequences of reduced wakefulness such as a shortened sleep latency, slowed cognitive function and prolonged reaction time can be measured objectively. It is, therefore, more promising to combine a battery of subjective and objective tests to answer a specific question in order to achieve the most appropriate description for a given clinical or medicolegal situation. However even then we must keep in mind that many other important aspects of fitness to drive / fitness to work such as neurological, psychiatric and neuropsychological functions including risk taking behaviour are not covered by vigilance tests. A comprehensive, multidisciplinary approach is essential in such situations.

Is excessive EEG beta activity associated with delinquent behavior in adult subjects with ADHD?

Objective: The attention deficit/hyperactivity disorder (ADHD) shows an increased prevalence in arrested offenders compared to the normal population. ADHD and delinquency seem to share some neurophysiological abnormalities. In recent studies, a subgroup of subjects with ADHD as well as delinquents displayed excessive EEG activity in the beta band compared to controls, which has been associated with antisocial behavior and aggression in ADHD children. The goal of the present study was to investigate whether delinquent behavior in ADHD is related to excessive beta activity. Methods: We compared the resting state EEGs (eyes closed and eyes open) of 13 non-delinquent and 13 delinquent subjects with ADHD and 13 controls regarding power spectra and topography of the EEG activity. Results: Offenders with ADHD showed more beta power mainly at frontal, central and parietal brain regions than non-delinquent subjects with ADHD. Conclusions: Excessive beta power may represent a risk-factor for delinquent behavior in adults with ADHD. Significance: The awareness of such risk-factors may be helpful in the assessment of the risk for delinquent behavior in a psychiatric context and may provide a neurobiological background for therapeutic interventions.

Daytime Low Stratiform Cloud Detection on AVHRR Imagery

The near-real time retrieval of low stratiform cloud (LSC) coverage is of vital interest for such disciplines as meteorology, transport safety, economy and air quality. Within this scope, a novel methodology is proposed which provides the LSC occurrence probability estimates for a satellite scene. The algorithm is suited for the 1 × 1 km Advanced Very High Resolution Radiometer (AVHRR) data and was trained and validated against collocated SYNOP observations. Utilisation of these two combined data sources requires a formulation of constraints in order to discriminate cases where the LSC is overlaid by higher clouds. The LSC classification process is based on six features which are first converted to the integer form by step functions and combined by means of bitwise operations. Consequently, a set of values reflecting a unique combination of those features is derived which is further employed to extract the LSC occurrence probability estimates from the precomputed look-up vectors (LUV). Although the validation analyses confirmed good performance of the algorithm, some inevitable misclassification with other optically thick clouds were reported. Moreover, the comparison against Polar Platform System (PPS) cloud-type product revealed superior classification accuracy. From the temporal perspective, the acquired results reported a presence of diurnal and annual LSC probability cycles over Europe.

Developmental changes in sleep biology and potential effects on adolescent behavior and caffeine use

Adolescent development includes changes in the biological regulatory processes for the timing of sleep. Circadian rhythm changes and changes to the sleep-pressure system (sleep homeostasis) during adolescence both favor later timing of sleep. These changes, combined with prevailing social pressures, are responsible for most teens sleeping too late and too little; those who sleep least report consuming more caffeine. Although direct research findings are scarce, the likelihood of use and abuse of caffeine-laden products grows across the adolescent years due, in part, to excessive sleepiness

Subjective perception of sleepiness in a driving simulator is different from that in the Maintenance of Wakefulness Test.

OBJECTIVE To test whether sleep-deprived, healthy subjects who do not always signal spontaneously perceived sleepiness (SPS) before falling asleep during the Maintenance of Wakefulness Test (MWT) would do so in a driving simulator. METHODS Twenty-four healthy subjects (20-26 years old) underwent a MWT for 40 min and a driving simulator test for 1 h, before and after one night of sleep deprivation. Standard electroencephalography, electrooculography, submental electromyography, and face videography were recorded simultaneously to score wakefulness and sleep. Subjects were instructed to signal SPS as soon as they subjectively felt sleepy and to try to stay awake for as long as possible in every test. They were rewarded for both "appropriate" perception of SPS and staying awake for as long as possible. RESULTS After sleep deprivation, seven subjects (29%) did not signal SPS before falling asleep in the MWT, but all subjects signalled SPS before falling asleep in the driving simulator (p <0.004). CONCLUSIONS The previous results of an "inaccurate" SPS in the MWT were confirmed, and a perfect SPS was shown in the driving simulator. It was hypothesised that SPS is more accurate for tasks involving continuous feedback of performance, such as driving, compared to the less active situation of the MWT. Spontaneously perceived sleepiness in the MWT cannot be used to judge sleepiness perception while driving. Further studies are needed to define the accuracy of SPS in working tasks or occupations with minimal or no performance feedback.

Biochemical changes in barley plants after excessive supply of copper and manganese

The present study was undertaken to identify changes in some important proteins involved in CO2 fixation (Rubisco, Rubisco activase (RA), Rubisco binding protein (RBP)), NH4+ assimilation (glutamine synthetase (GS) and glutamate synthase (GOGAT)), using immunoblotting, and in the antioxidative defense as a result of Cu or Mn excess in barley leaves (Hordeum vulgare L. cv. Obzor). Activities and isoenzyme patterns of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT), as well as the levels of ascorbate (ASC), non-protein sulfhydryl groups, hydrogen peroxide and oxidative damage to proteins were determined. Data were correlated to the accumulation of Cu or Mn in the leaves after 5 days supply of heavy metal (HM) excess in the nutrient solution. In the highest Cu excess (1500 μM), Rubisco LS and SS were reduced considerably whereas under the highest Mn concentrations (18,300 μM) only minor changes in Rubisco subunits were detected. The RBP was diminished under the highest concentrations of both Cu or Mn. The bands of RA changed differently comparing Cu and Mn toxicity. GS decreased and GOGAT was absent under the highest concentration of Cu. At Mn excess Fd-GOGAT diminished whereas GS was not apparently changed. The development of toxicity symptoms corresponded to an accumulation of Cu or Mn in the leaves and to a gradual increase in protein carbonylation, a lower SOD activity and elevated CAT and GPX activities. APX activity was diminished under Mn toxicity and was not changed under Cu excess. Generally, changes in the isoenzyme profiles were similar under both toxicities. An accumulation of H2O2 was observed only at Mn excess. Contrasting changes in the low-molecular antioxidants were detected when comparing both toxicities. Cu excess affected mainly the non-protein SH groups, while Mn influenced the ASC content. Oxidative stress under Cu or Mn toxicity was most probably the consequence of depletion in low-molecular antioxidants as a result of their involvement in detoxification processes and disbalance in antioxidative enzymes. The link between heavy metal accumulation in leaves, leading to different display of oxidative stress, and changes in individual chloroplast proteins is discussed in the article.

Phosphatidylethanol (PEth) in blood samples from "driving under the influence" cases as indicator for prolonged excessive alcohol consumption.

Phosphatidylethanol (PEth) is considered as specific biomarker of alcohol consumption. Due to accumulation after repeated drinking, PEth is suitable to monitor long-term drinking behavior. To examine the applicability of PEth in "driving under the influence of alcohol" cases, 142 blood samples with blood alcohol concentrations (BAC) ranging from 0.0-3.12 ‰ were analyzed for the presence of PEth homologues 16:0/18:1 (889 ± 878 ng/mL; range excessive alcohol consumption with acceptable sensitivity and specificity in accordance with the 1.6 ‰ BAC limit. With a threshold of 700 ng/mL for PEth 16:0/18:1, prolonged excessive alcohol consumption was detected in 65.9 % of drunk drivers with a BAC ≥ 1.6 ‰ and in 31.6 % of the samples with a BAC < 1.6 ‰. Similar results were obtained for PEth 16:0/18:2 with a threshold of 300 ng/mL. Both criteria, PEth 16:0/18:1 and PEth 16:0/18:2, were conform in the evaluation of drinking habits in 88.7 % of blood samples. These results show the possibility to detect prolonged excessive alcohol consumption, even if the BAC is below the legal threshold of 1.6 ‰ for driving aptitude assessment. As a consequence, concentrations of PEth 16:0/18:1 ≥ 700 ng/mL and of PEth 16:0/18:2 ≥ 300 ng/mL may be considered as indicators for the necessity of driving aptitude assessment in addition to BAC.

Periacetabular osteotomy restores the typically excessive range of motion in dysplastic hips with a spherical head

BACKGROUND Residual acetabular dysplasia is seen in combination with femoral pathomorphologies including an aspherical femoral head and valgus neck-shaft angle with high antetorsion. It is unclear how these femoral pathomorphologies affect range of motion (ROM) and impingement zones after periacetabular osteotomy. QUESTIONS/PURPOSES (1) Does periacetabular osteotomy (PAO) restore the typically excessive ROM in dysplastic hips compared with normal hips; (2) how do impingement locations differ in dysplastic hips before and after PAO compared with normal hips; (3) does a concomitant cam-type morphology adversely affect internal rotation; and (4) does a concomitant varus-derotation intertrochanteric osteotomy (IO) affect external rotation? METHODS Between January 1999 and March 2002, we performed 200 PAOs for dysplasia; of those, 27 hips (14%) met prespecified study inclusion criteria, including availability of a pre- and postoperative CT scan that included the hip and the distal femur. In general, we obtained those scans to evaluate the pre- and postoperative acetabular and femoral morphology, the degree of acetabular reorientation, and healing of the osteotomies. Three-dimensional surface models based on CT scans of 27 hips before and after PAO and 19 normal hips were created. Normal hips were obtained from a population of CT-based computer-assisted THAs using the contralateral hip after exclusion of symptomatic hips or hips with abnormal radiographic anatomy. Using validated and computerized methods, we then determined ROM (flexion/extension, internal- [IR]/external rotation [ER], adduction/abduction) and two motion patterns including the anterior (IR in flexion) and posterior (ER in extension) impingement tests. The computed impingement locations were assigned to anatomical locations of the pelvis and the femur. ROM was calculated separately for hips with (n = 13) and without (n = 14) a cam-type morphology and PAOs with (n = 9) and without (n = 18) a concomitant IO. A post hoc power analysis based on the primary research question with an alpha of 0.05 and a beta error of 0.20 revealed a minimal detectable difference of 4.6° of flexion. RESULTS After PAO, flexion, IR, and adduction/abduction did not differ from the nondysplastic control hips with the numbers available (p ranging from 0.061 to 0.867). Extension was decreased (19° ± 15°; range, -18° to 30° versus 28° ± 3°; range, 19°-30°; p = 0.017) and ER in 0° flexion was increased (25° ± 18°; range, -10° to 41° versus 38° ± 7°; range, 17°-41°; p = 0.002). Dysplastic hips had a higher prevalence of extraarticular impingement at the anteroinferior iliac spine compared with normal hips (48% [13 of 27 hips] versus 5% [one of 19 hips], p = 0.002). A PAO increased the prevalence of impingement for the femoral head from 30% (eight of 27 hips) preoperatively to 59% (16 of 27 hips) postoperatively (p = 0.027). IR in flexion was decreased in hips with a cam-type deformity compared with those with a spherical femoral head (p values from 0.002 to 0.047 for 95°-120° of flexion). A concomitant IO led to a normalization of ER in extension (eg, 37° ± 7° [range, 21°-41°] of ER in 0° of flexion in hips with concomitant IO compared with 38° ± 7° [range, 17°-41°] in nondysplastic control hips; p = 0.777). CONCLUSIONS Using computer simulation of hip ROM, we could show that the PAO has the potential to restore the typically excessive ROM in dysplastic hips. However, a PAO can increase the prevalence of secondary intraarticular impingement of the aspherical femoral head and extraarticular impingement of the anteroinferior iliac spines in flexion and internal rotation. A cam-type morphology can result in anterior impingement with restriction of IR. Additionally, a valgus hip with high antetorsion can result in posterior impingement with decreased ER in extension, which can be normalized with a varus derotation IO of the femur. However, indication of an additional IO needs to be weighed against its inherent morbidity and possible complications. The results are based on a limited number of hips with a pre- and postoperative CT scan after PAO. Future prospective studies are needed to verify the current results based on computer simulation and to test their clinical importance.