Sleep patterns of day-working, evening high-schooled adolescents of São Paulo, Brazil

Children who grow up in developing countries of the world must work to help financially support their families, and they must also attend school. We investigated the impact of work on the sleep of working vs. nonworking high school students. Twenty-seven S?o Paulo, Brazil, public high school students (eight male and eight female working students plus six nonworking female and five nonworking male students) 14-18 yrs of age who attended school Monday-Friday between 19:00 to 22:30h participated. A comprehensive questionnaire about work and living conditions, health status, and diseases and their symptoms was also answered. The activity level and rest pattern (sleep at night and napping during the day) were continuously assessed by wrist actigraphy (Ambulatory Monitoring, USA). The main variables were analyzed by a two-factor ANOVA with application of the Tukey HSD test for multiple comparisons, and the length of sleep during weekdays vs. weekends was compared by Student t-test. Working students went to sleep earlier weekends [F(1,23)=6.1; p=0.02] and woke up earlier work days than nonworking students [F(1,23) = 17.3; p = 0.001]. The length of nighttime sleep during weekdays was shorter among all the working [F(1,23)= 16.7; p <0.001] than all the nonworking students. The sleep duration of boys was shorter than of girls during weekends [F(1,23)= 10.8; p <0.001]. During weekdays, the duration of napping by working and nonworking male students was shorter than nonworking female students. During weekdays working girls took the shortest naps [F(1,23)= 5.6; p = 0.03]. The most commonly reported sleep complaint during weekdays was difficulty waking up in the morning [F(1,23) = 6.5; p = 0.02]. During weekdays, the self-perceived sleep quality of working students was worse than nonworking students [F(1,23) = 6.2; p = 0.02]. The findings of this study show that work has negative effects on the sleep of adolescents, with the possible build-up of a chronic sleep debt with potential consequent impact on quality of life and school learning.     

Effects of alcohol on psycho-technical tests and social communication in a festive situation: a chronopsychological approach

The aim of this study was to determine the effect of consuming alcoholic vs. nonalcoholic beverages on performance of psycho-technical tasks (attentional and general nonverbal intelligence tasks) and social behavior at different times of day. Both alcoholic and nonalcoholic consumption took place in a largely festive situation. The experiment was conducted on 184 degree-level and postgraduate students (94 female and 90 male) divided into eight independent groups for study at different times: 8:00 to 11:00, 11:00 to 14:00, 14:00 to 17:00, 17:00 to 20:00h. The main result obtained, by analysis of variance (ANOVA), showed that time of day had no effect on the performance of psycho-technical tasks nor on social communication, except for the retest situation in the attentional task. Alcohol (equal to approximately 0.5 g/L of blood) facilitated communication, but basically it had no effect on any of the psycho-technical performance tests. For the latter, an interaction was observed between when the test was done and type of beverage consumed. Alcohol appears to alter the expected change in performance in the retest situation. The results suggest that the body's sensitivity to a measured quantity of alcohol differs according to the cognitive processes involved.     

Hereditary deafness: molecular genetics

This article outlines recent advances in explaining hereditary deafness in molecular terms, focusing on isolated (i.e. nonsyndromic) hearing loss. The number of genes identified (36 to date) is growing rapidly. However, difficulties inherent in genetic linkage analysis, coupled with the possible involvement of environmental causes, have so far prevented the characterization of the main genes causative or predisposing to the late-onset forms of deafness.     

Genetic basis of planar polarity

Several epitheliums exhibit a clear polarity that lies within the plane of the epithelium. This polarity, referred to as planar polarity or tissue polarity, is oriented perpendicular to the apical-basal polarity of the epithelium. Over the last two decades, the genetic and molecular bases of planar polarity have been intensively investigated in Drosophila. Recent studies have shown that establishment of planar polarity relies on the unipolar distribution of a small number of signaling molecules localizing at the apical cortex. Unipolar localization of planar polarity proteins defines two opposite and complementary cortical domains. These domains show a stereotyped orientation at the tissue level. Positioning of these cortical domains is coordinated at the tissue level by a second class of signaling molecules that form an activity gradient across the epithelium. Together these data have led to a general model of planar polarity establishment. Considering that planar polarity genes have been conserved from flies to vertebrates, this model may be useful for our understanding of epithelium biology in mammals.     

Does clinical research provide any "direct individual benefit"?

The European Commission and Parliament have promulgated a directive on clinical research (2001/20/CE) in April 2001. Its provisions have to be incorporated in all national laws by May 2004. Accordingly, the French " loi Huriet " (a law passed in 1988 organizing clinical research in France) had to be revised. During the process, it appeared that a key issue was the suppression of a distinction made by this law between research with and without " direct individual benefit ", a French specificity, as the directive recommends rather the assessment of the risk/benefit ratio. In order to harmonize the French legislation with the other European laws, and to suppress a set of provisions which have been repeatedly attacked during the last ten years, the French members of parliament have voted on October 2003 a new law which, among other important modifications, suppress that distinction.     

Origin of resistance to Imatinib mesylate: lessons learned from this experience

For drug development and pharmaceutical research, targeting the molecular abnormalities is considered as a new challenge. A number of diseases including cancer are linked to perturbation of tyrosine kinase (TK). Imatinib (Glivec or Gleevec, Novartis), the most potent inhibitor of c-abl TK, was recently developed. This molecule has been approved in the treatment of chronic myeloid leukemia (CML). However, emergence of clinical resistance regarding a low rate of CML patients leads to intensive research. In the current article, we discuss the data and the mechanism of the resistance phenomenon. This review illustrates the important requirement to transfer back the information from patient to laboratory in order to improve future drug design.     

Validation of Horne and Ostberg morningness-eveningness questionnaire in a middle-aged population of French workers

As suggested by the authors, the Horne and Ostberg morning/evening questionnaire (MEQ) has never been adapted to evaluate a nonstudent population. The purpose of this study was to validate this MEQ in a sample of middle-aged workers by modifying only the cutoffs. It was administered in 566 non-shift-workers aged 51.2 to 3.2 years who presented no sleep disorders. According to the Home and Ostberg classification, the sample consisted of 62.1% morning type, 36.6% neither type, and 2.2% evening type. Multiple correspondence analysis, which determines the principal components, was performed on all MEQ items. Then an ascending hierarchical classification was applied to determine 3 clusters from these principal components. On the basis of these 3 clusters, new cutoffs were determined: evening types were considered as scoring under 53 and morning types above 64, thus giving 28.1% morning type, 51.7% neither type, and 20.2% evening type. As an external validation, eveningness was associated with later bedtime and waking-up time (more pronounced at the weekend), greater need for sleep, larger daily sleep debt, greater morning sleepiness, and ease of returning to sleep in the early morning. A positive correlation between age and morningness was again found. This study confirms that "owls" are not rare in a middle-aged sample. We conclude that this adapted MEQ could be useful when investigating age-related changes in sleep.     

FRET multiphoton spectral imaging microscopy of 7-ketocholesterol and Nile Red in U937 monocytic cells loaded with 7-ketocholesterol

OBJECTIVE: To show the effect of 7-ketocholesterol (7KC) on cellular lipid content by means of flow cytometry and the interaction of 7KC with Nile Red (NR) via ultraviolet fluorescence resonance energy transfer (FRET) excitation of NR on U937 monocytic cells by means of 2-photon excitation confocal laser scanning microscopy (CLSM). STUDY DESIGN: Untreated and 7KC-treated U937 cells were stained with NR and analyzed by flow cytometry and CLSM. 3D sequences of images were obtained by spectral analysis in a 2-photon excitation CLSM and analyzed by the factor analysis of medical image sequences (FAMIS) algorithm, which provides factor curves and images. Factor images are the result of the FAMIS image processing method, which handles emission spectra. In FRET analysis, preparations are screened at selected UV wavelengths to avoid emission of NR in the absence of 7KC. RESULTS: During 7KC-induced cell death,flow cytometry and CLSM revealed a modification of the cellular lipid content. Factor images show FRET occurrence and subsequent colocalization of 7KC and NR. CONCLUSION: This investigation established the utility of 2-photon excitation CLSM to assess colocalization of 7KC with NR by FRET and to identify and distinguish polar and neutral lipids stained by NR that accumulate from the effect of 7KC.     

Protein secondary structure assignment through Voronoï tessellation

We present a new automatic algorithm, named VoTAP (Vo ronoï T essellation A ssignment P rocedure), which assigns secondary structures of a polypeptide chain using the list of α‐carbon coordinates. This program uses three‐dimensional Voronoï tessellation. This geometrical tool associates with each amino acid a Voronoï polyhedron, the faces of which unambiguously define contacts between residues. Thanks to the face area, for the contacts close together along the primary structure (low‐order contacts) a distinction is made between strong and normal ones. This new definition yields new contact matrices, which are analyzed and used to assign secondary structures. This assignment is performed in two stages. The first one uses contacts between residues close together along the primary structure and is based on data collected on a bank of 282 well‐refined nonredundant structures. In this bank, associations were made between the prints defined by these low‐order contacts and the assignments performed by different automatic methods. The second step focuses on the strand assignment and uses contacts between distant residues. Comparison with several other automatic assignment methods are presented, and the influence of resolution on the assignment is investigated. Proteins 2004. © 2004 Wiley‐Liss, Inc.