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  1. Article ; Online: Characterization of circulating leptin-receptor levels following acute sleep restriction: A pilot study on healthy adult females.

    Azzi, Elissar / Fayyad-Kazan, Mohammad / Kabrita, Colette S

    Physiology & behavior

    2024  Volume 279, Page(s) 114543

    Abstract: Background: Insufficient sleep adversely affects energy homeostasis by decreasing leptin levels. The underlying physiological mechanisms; however, remain unclear. Circulating leptin is well described to be regulated by its soluble receptor (sOB-R). ... ...

    Abstract Background: Insufficient sleep adversely affects energy homeostasis by decreasing leptin levels. The underlying physiological mechanisms; however, remain unclear. Circulating leptin is well described to be regulated by its soluble receptor (sOB-R). Intriguingly, the impact of short sleep duration on sOB-R levels has never been characterized.
    Aim: In this study, we investigated, for the first time, the variation of sOB-R levels and its temporal relationship with circulating leptin upon acute sleep restriction.
    Methods: Five adult females were maintained on an 8-hour sleep schedule (bedtime at 00:00) for 1 week before restricting their sleep to 4.5 h (bedtime at 03:30) on 2 consecutive nights. Balanced meals were scheduled to specific hours and sleep was objectively measured. Four-hour blood samples were regularly collected during waking hours between 08:00 and 00:00.
    Results: Sleep restriction resulted in lower leptin (20.9 ± 1.7 vs 25.7 ± 1.7 ng/ml) and higher sOB-R concentrations (24.4 ± 1.2 vs 19.8 ± 1.6 ng/ml). Neither the discordant temporal relationship nor the pattern of leptin and sOB-R were altered in response to sleep restriction.
    Conclusion: Our results suggest that sleep restriction may modulate circulating leptin levels and possibly metabolism via upregulating its soluble receptor. This observation may have valuable therapeutic implications when considering sOB-R as a potential target during the management of metabolic disturbances.
    MeSH term(s) Humans ; Female ; Leptin ; Pilot Projects ; Receptors, Leptin ; Receptors, Cell Surface/metabolism ; Carrier Proteins ; Sleep
    Chemical Substances Leptin ; Receptors, Leptin ; Receptors, Cell Surface ; Carrier Proteins
    Language English
    Publishing date 2024-03-31
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3907-x
    ISSN 1873-507X ; 0031-9384
    ISSN (online) 1873-507X
    ISSN 0031-9384
    DOI 10.1016/j.physbeh.2024.114543
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: The temporal expression pattern of classical MHC class I in sleep-restricted mice: Generalizations and broader implications.

    Kabrita, Colette S / Al Bitar, Samar / Ghanem, Esther

    Brain, behavior, & immunity - health

    2024  Volume 37, Page(s) 100751

    Abstract: The intricate relationship between sleep and leukocyte trafficking has garnered intense attention, particularly their homing dynamics to secondary lymphoid organs under normal and restricted sleep (SR). Considering the scarcity of information regarding ... ...

    Abstract The intricate relationship between sleep and leukocyte trafficking has garnered intense attention, particularly their homing dynamics to secondary lymphoid organs under normal and restricted sleep (SR). Considering the scarcity of information regarding circadian rhythms in major histocompatibility class I (MHC-I) expression in SR, we designed a study that assessed the temporal expression of MHC-I in murine lymph nodes and spleen and the subsequent effects of sleep recovery. Male C57BL/6, housed in 12:12 light/dark cycle, were grouped into control (C) and SR. SR was carried for one week before lymphoid tissues were sampled at selected time points and assessed for leukocyte number and MHC-I expression. SR resulted in 21% decrease in granulocyte and 24% increase in agranulocyte numbers. In C, MHC-I expression pattern in lymph nodes was bimodal and relatively higher than splenocytes during the animal's active phase (110.2 ± 1.8 vs 81.9 ± 3.8, respectively; p = 0.002). Splenocytes; however, showed a bimodal pattern upon SR, with higher protein levels during the rest than the activity period (154.6 + 36.2 vs 99.5 + 15.9, respectively; p = 0.002), suggesting preparedness for a potential infection. Furthermore, SR caused a significant drop in MHC-I expression at the onset of rest with 57% and 30% reduction in lymph nodes and splenocytes, respectively. However, the overall protein expression collectively taken from both lymphoid tissues remained stable, emphasizing its indispensable role in immunological homeostasis. This stability coincided with the restoration of protein levels to baseline after a short sleep recovery period, resembling a reset for MHC-I antigen presentation following a week of SR. Understanding the interplay between MHC-I expression and contextual factors could enhance treatment protocols, refining the efficacy and time precision of glucocorticoid-based therapies in immune modulation.
    Language English
    Publishing date 2024-03-11
    Publishing country United States
    Document type Journal Article
    ISSN 2666-3546
    ISSN (online) 2666-3546
    DOI 10.1016/j.bbih.2024.100751
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Sleep restriction alters the temporal expression of major histocompatibility complex class II molecules in murine lymphoid tissues.

    Ghanem, Esther / Al Bitar, Samar / Dib, Robert / Kabrita, Colette S

    Behavioural brain research

    2019  Volume 362, Page(s) 152–159

    Abstract: Inadequate sleep is a major health concern of modern societies in view of the increased morbidity and mortality rates from physiological disturbances, including compromised adaptive immune responses. Many studies investigated the effect sleep restriction ...

    Abstract Inadequate sleep is a major health concern of modern societies in view of the increased morbidity and mortality rates from physiological disturbances, including compromised adaptive immune responses. Many studies investigated the effect sleep restriction (SR) on the normal immune response in terms of leukocyte number and circulating cytokine and T helper cell (Th) profiles, but none considered the major histocompatibility complex (MHC), namely class II molecules. As no information exists about the normal temporal expression of MHC class II, the present study aimed at understanding how SR affects the adaptive immune response via altering the 1) normal daily expression profile and 2) overall constitutive levels of murine MHC class II by leukocytes' isolates from spleen and axillary lymph nodes. Male C57BL/6 mice were acclimatized to 12:12 light/dark cycle (lights on at 0700, corresponding to Zeitgeber time (ZT) 0) for a week before splitting into 2 groups: control (C) and SR (exposed to a 12 and 18 h of activity, respectively). SR was carried for one week before lymphoid tissues from both C and SR mice were sampled at the following time points: ZT0, ZT5, ZT10, ZT13, and ZT18. Spleen and lymph node cells were assessed for leukocyte number and MHC class II expression at the preselected time points using flow cytometry. SR resulted in a 21% decrease in granulocyte and 24% increase in agranulocyte numbers. MHC class II expression in both lymphoid tissues of C mice varied synchronously across the preselected times of day; they were relatively high just prior to activity onset and later in this period. Comparatively, the diurnal protein profile was altered in both lymphoid tissues of SR: 1) the rise of MHC class II expression during the rest period occurred 4-5 hours earlier and 2) the cyclical pattern during the activity period was blunted and protein expression was maintained at relatively high levels. MHC class II expression was higher in the lymph nodes and lower in the spleen of SR than C, though these differences did not reach statistical significance. In SR; however, the average protein level was significantly higher in lymph nodes than spleen (376.0 + 184.9 vs 188.6 + 42.2, respectively; p = .002) and higher in the granulocytes relative to agranulocytes. Our findings provide empirical evidence of a constitutive diurnal expression pattern for MHC class II molecules that is prone to upregulation upon SR, namely in lymph nodes, and specifically expressed by granulocytes. We speculate that, in mice, chronic sleep deprivation would further dysregulate MHC class II expression that might result in aberrant T cell activation with probable immune-associated pathological diseases such as allergies, autoimmunity, and tumors.
    MeSH term(s) Animals ; Histocompatibility Antigens Class II/metabolism ; Interferon-gamma/metabolism ; Leukocytes/metabolism ; Lymphoid Tissue/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Sleep/physiology ; Spleen/metabolism
    Chemical Substances Histocompatibility Antigens Class II ; Interferon-gamma (82115-62-6)
    Language English
    Publishing date 2019-01-11
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 449927-x
    ISSN 1872-7549 ; 0166-4328
    ISSN (online) 1872-7549
    ISSN 0166-4328
    DOI 10.1016/j.bbr.2019.01.019
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Sex-specific sleep patterns among university students in Lebanon: impact on depression and academic performance.

    Kabrita, Colette S / Hajjar-Muça, Theresa A

    Nature and science of sleep

    2016  Volume 8, Page(s) 189–196

    Abstract: Good sleep quality and quantity are fundamental to the maintenance of normal physiological processes. Changes in sleep patterns are commonly observed among young adults and are shown to impact neurocognitive, academic, and psychological well-being. Given ...

    Abstract Good sleep quality and quantity are fundamental to the maintenance of normal physiological processes. Changes in sleep patterns are commonly observed among young adults and are shown to impact neurocognitive, academic, and psychological well-being. Given the scarcity of sleep information about Lebanon and acknowledging the sex differences in various sleep dimensions, we conducted a study that aimed at assessing sex differences in sleep habits among university students in Lebanon in relation to psychoacademic status. A total of 540 students (50.6% females) completed a questionnaire that inquired about sociodemographics and evaluated sleep quality and depression using the Pittsburg Sleep Quality Index (PSQI) and Center for Epidemiological Studies Depression Scale (CES-D), respectively. The mean PSQI global score (6.57±3.49) indicated poor sleep, with no significant differences between men and women. The sleep/wake rhythm was delayed on weekends for both sexes. Females exhibited earlier bedtimes and rise times and longer sleep durations on both weekdays and weekends. However, unlike males females showed a greater phase delay in wake times than bedtimes on weekends (149 minutes vs 74 minutes, respectively). In all, 70.9% of females suffered from depressive symptoms, which was a significantly higher proportion compared with 58.5% of males (P<0.01). Based on the mean cumulative self-reported grade point average (GPA), the academic performance of females was significantly better than that of males (2.8±0.61 vs 2.65±0.61, P<0.05, respectively). Depression, as scored by CES-D, in females was significantly negatively correlated with the cumulative GPA (r=-0.278, P<0.01), earlier wake time (r=-0.168, P<0.05), and average sleep duration (r=-0.221, P<0.01) on weekdays. GPA of males was significantly correlated with bedtime on weekends (r=-0.159, P<0.05). We conclude that sex differences in sleep timing, such as bedtime/rise time and nocturnal sleep duration, rather than sleep quality exist among Lebanese university students. Sex-specific sleep patterns have differential impact on psychological and academic well-being.
    Language English
    Publishing date 2016-06-17
    Publishing country New Zealand
    Document type Journal Article
    ZDB-ID 2587468-8
    ISSN 1179-1608
    ISSN 1179-1608
    DOI 10.2147/NSS.S104383
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Predictors of poor sleep quality among Lebanese university students: association between evening typology, lifestyle behaviors, and sleep habits.

    Kabrita, Colette S / Hajjar-Muça, Theresa A / Duffy, Jeanne F

    Nature and science of sleep

    2014  Volume 6, Page(s) 11–18

    Abstract: Adequate, good night sleep is fundamental to well-being and is known to be influenced by myriad biological and environmental factors. Given the unavailability of sleep data about Lebanon, the cultural shifts and socioeconomic pressures that have affected ...

    Abstract Adequate, good night sleep is fundamental to well-being and is known to be influenced by myriad biological and environmental factors. Given the unavailability of sleep data about Lebanon, the cultural shifts and socioeconomic pressures that have affected many aspects of society, particularly for students and working adults, as well as our understanding of sleep in university students in other countries, we conducted a national study to assess sleep quality and factors contributing to sleep and general health in a culture-specific context. A self-filled questionnaire, inquiring about sociodemographics, health-risk behaviors, personal health, and evaluating sleep quality and chronotype using standard scales was completed by 540 students at private and public universities in Lebanon. Overall, they reported sleeping 7.95±1.34 hours per night, although 12.3% reported sleeping <6.5 hours and more than half scored in the poor-sleeper category on the Pittsburgh Sleep Quality Index (PSQI). Sleep timing differed markedly between weekdays and weekends, with bedtimes and wake-up times delayed by 1.51 and 2.43 hours, respectively, on weekends. While most scored in the "neither type" category on the Morningness-Eveningness Questionnaire (MEQ), 24.5% were evening types and 7.3% were morning types. MEQ score was significantly correlated with smoking behavior and daily study onset, as well as with PSQI score, with eveningness associated with greater number of cigarettes, later study times, and poor sleep. We conclude that the prevalence of poor sleep quality among Lebanese university students is associated with reduced sleep duration and shifts in sleep timing between weekdays and weekends, especially among evening types. While chronotype and certain behavioral choices interact to affect sleep dimensions and quality, raising awareness about the importance of obtaining adequate nighttime sleep on daily performance and avoiding risky behaviors may help Lebanese students make better choices in school and work schedules.
    Language English
    Publishing date 2014-01-13
    Publishing country New Zealand
    Document type Journal Article
    ZDB-ID 2587468-8
    ISSN 1179-1608
    ISSN 1179-1608
    DOI 10.2147/NSS.S55538
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Development of the mouse suprachiasmatic nucleus: determination of time of cell origin and spatial arrangements within the nucleus.

    Kabrita, Colette S / Davis, Fred C

    Brain research

    2007  Volume 1195, Page(s) 20–27

    Abstract: The suprachiasmatic nucleus (SCN) in mammals functions as the principal circadian pacemaker synchronizing diverse physiological and behavioral processes to environmental stimuli. It consists of heterogeneous populations of cells with unique spatial ... ...

    Abstract The suprachiasmatic nucleus (SCN) in mammals functions as the principal circadian pacemaker synchronizing diverse physiological and behavioral processes to environmental stimuli. It consists of heterogeneous populations of cells with unique spatial organization that can vary among species, but are commonly discussed within a framework of two principal regions, the ventrolateral or dorsomedial halves of the nucleus or in other instances the core and shell. In both hamsters and rats, cells of different SCN regions have been shown to have different developmental histories. Using bromodeoxyuridine as a marker of cell division, the present study investigated the time of SCN cell origin in mice (C57BL/6) and their settling patterns within the nucleus. Results show that SCN cytogenesis occurs between embryonic days 12 and 15 and is complete 5 days prior to birth. Cells born on embryonic day 12 are mainly confined to a ventrolateral region of the mid-SCN, whereas cells produced later on embryonic days 13.5 and 14.5 form a cap around the cells produced first and extend into the posterior and anterior ends of the nucleus. These results suggest an ordered spatiotemporal program of SCN cytogenesis whereby a mid-SCN core is born first followed by a surrounding shell of later-born cells. Variations in cytogenesis could affect the relative sizes of different SCN regions and, thereby, affect its function. The relative contributions of a highly ordered program of cytogenesis and intercellular interactions after postmitotic cells leave the germinal epithelium remain to be determined.
    MeSH term(s) Animals ; Cell Differentiation/physiology ; Cell Movement/physiology ; Embryonic Stem Cells/cytology ; Embryonic Stem Cells/physiology ; Female ; Mice ; Mice, Inbred C57BL ; Organogenesis/physiology ; Pregnancy ; Suprachiasmatic Nucleus/cytology ; Suprachiasmatic Nucleus/embryology ; Time Factors
    Language English
    Publishing date 2007-12-23
    Publishing country Netherlands
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1200-2
    ISSN 1872-6240 ; 0006-8993
    ISSN (online) 1872-6240
    ISSN 0006-8993
    DOI 10.1016/j.brainres.2007.12.020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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