Mammalian sleep

Resilience of the immune system in healthy young students to 30-hour sleep deprivation with psychological stress

OBJECTIVE

Young adults often encounter sleep deprivation and stressful events. Both have been separately reported to modulate immunity, and occasionally they occur simultaneously. We assessed the combined effects of these conditions on immune competence in healthy students.

METHODS

Twenty-three participants (mean age 24 years; SD 1.86; 14 females) were exposed to 30 h of sleep deprivation during which they conducted physiological, social and cognitive tasks. The control group consisted of 18 participants (mean age 23.67 years; SD 1.46; 11 females). All participants underwent cognitive and psychological evaluations at 10:00 AM, followed by blood and saliva collection, 3 days before sleep deprivation induction and on the morning following it. Immune/endocrine measures included blood counts of lymphocytes, granulocytes, monocytes and natural killer (NK) cells; levels of several cell surface markers; NK cytotoxicity; plasma levels of interleukin (IL)-6, IL-10, dehydroepiandrosterone and neuropeptide Y, and plasma and salivary cortisol levels.

RESULTS

Although the experimental protocol significantly elevated state anxiety and psychological dissociation levels, no effects were evident in any of the immunological/endocrine indices. In contrast, expected sex differences in immune measures were found, including significantly higher NK cytotoxicity and monocyte counts in males, validating the integrity of the measurements.

CONCLUSIONS

The findings suggest resilience of the immune system to a combined sleep deprivation and stressful exposure in young adults, while previous studies reported immune perturbations following either of these conditions separately. These apparent contradictions might reflect differences in the study design or in the methodology used for immunological assessments, including the time of sample collection, the combination of sleep deprivation with stress and our in vivo assessment of cytokine levels.

Postnatal expression pattern of HCN channel isoforms in thalamic neurons: relationship to maturation of thalamocortical oscillations

Hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels are the molecular substrate of the hyperpolarization-activated inward current (I(h)). Because the developmental profile of HCN channels in the thalamus is not well understood, we combined electrophysiological, molecular, immunohistochemical, EEG recordings in vivo, and computer modeling techniques to examine HCN gene expression and I(h) properties in rat thalamocortical relay (TC) neurons in the dorsal part of the lateral geniculate nucleus and the functional consequence of this maturation. Recordings of TC neurons revealed an approximate sixfold increase in I(h) density between postnatal day 3 (P3) and P106, which was accompanied by significantly altered current kinetics, cAMP sensitivity, and steady-state activation properties. Quantification on tissue levels revealed a significant developmental decrease in cAMP. Consequently the block of basal adenylyl cyclase activity was accompanied by a hyperpolarizing shift of the I(h) activation curve in young but not adult rats. Quantitative analyses of HCN channel isoforms revealed a steady increase of mRNA and protein expression levels of HCN1, HCN2, and HCN4 with reduced relative abundance of HCN4. Computer modeling in a simplified thalamic network indicated that the occurrence of rhythmic delta activity, which was present in the EEG at P12, differentially depended on I(h) conductance and modulation by cAMP at different developmental states. These data indicate that the developmental increase in I(h) density results from increased expression of three HCN channel isoforms and that isoform composition and intracellular cAMP levels interact in determining I(h) properties to enable progressive maturation of rhythmic slow-wave sleep activity patterns.

Canine cytogenetics--from band to basepair

Humans and dogs have coexisted for thousands of years, during which time we have developed a unique bond, centered on companionship. Along the way, we have developed purebred dog breeds in a manner that has resulted unfortunately in many of them being affected by serious genetic disorders, including cancers. With serendipity and irony the unique genetic architecture of the 21st century genome of Man's best friend may ultimately provide many of the keys to unlock some of nature's most intriguing biological puzzles. Canine cytogenetics has advanced significantly over the past 10 years, spurred on largely by the surge of interest in the dog as a biomedical model for genetic disease and the availability of advanced genomics resources. As such the role of canine cytogenetics has moved rapidly from one that served initially to define the gross genomic organization of the canine genome and provide a reliable means to determine the chromosomal location of individual genes, to one that enabled the assembled sequence of the canine genome to be anchored to the karyotype. Canine cytogenetics now presents the biomedical research community with a means to assist in our search for a greater understanding of how genome architectures altered during speciation and in our search for genes associated with cancers that affect both dogs and humans. The cytogenetics 'toolbox' for the dog is now loaded. This review aims to provide a summary of some of the recent advancements in canine cytogenetics.