Influence of T-lymphocyte deprivation on the antileukemic effect of bacillus calmette-guérin in vivo

Summary The effect in AKR mice of T-lymphocyte deprivation in vivo, obtained by adult thymectomy plus/minus whole-body irradiation and bone-marrow reconstitution, was studied in the growth of grafted leukemia cells obtained from spontaneous AKR leukemia. Both thymectomized mice and mice subjected to thymectomy, whole-body irradiation, and bone-marrow reconstitution (B) had a lower take-frequency of graft leukemia than conventional mice. Growth of graft leukemia was inhibited by BCG treatment both in thymectomized mice and in B mice. Concomitant with the increased inhibition of leukemia growth, an increased incidence of wasting-like disease was observed. In vitro cytotoxicity studies revealed that spleen lymphoid cells from nonleukemic mice were cytotoxic to AKR leukemia cells, to nonmalignant AKR fibroblasts, and to other nonmalignant cells with H-2^k haplotype. The activity of this self-directed cytotoxicity was most marked in AKR mice with wasting-like disease. The presence of autocytotoxic cells was frequently associated with a positive direct Coombs' test. Immunofluorescence studies showed, further, that the cytotoxic activity was independent of retrovirus antigens as tested by indirect immunofluorescence with anti-MuLV antibodies. Adult thymectomy of AKR mice confers an increased antitumoral immune potential, but also an increased risk of development of serious autoimmune disease.     

Effects of two nights partial sleep deprivation on an evening submaximal weightlifting performance; are 1 h powernaps useful on the day of competition?

We have investigated the effects that sleep restriction (3-h sleep during two consecutive nights) have on an evening (17:00 h) submaximal weightlifting session; and whether this performance improves following a 1-h post-lunch powernap. Fifteen resistance-trained males participated in this study. Before the experimental protocol commenced, 1RM bench press and inclined leg press and normative habitual sleep were recorded. Participants were familiarised with the testing protocol, then completed three experimental conditions with two nights of prescribed sleep: (i) Normal (N): retire at 23:00 h and wake at 06:30 h, (ii) partial sleep-deprivation (SD): retire at 03:30 h and wake at 06:30 h and (iii) partial sleep-deprivation with nap (SD_N): retire at 03:30 h and wake at 06:30 h with a 1-h nap at 13:00 h. Each condition was separated by at least 7 days and the order of administration was randomised and counterbalanced. Rectal (T_rec) and mean skin (T_s) temperatures, Profile of Mood Scores, subjective tiredness, alertness and sleepiness values were measured at 08:00, 11:00, 14:00 and 17:00 h on the day of the weightlifting session. Following the final temperature measurements at 17:00 h, participants completed a 5-min active warm-up before a ‘strength’ protocol. Participants performed three repetitions of right-hand grip strength, then three repetitions at each incremental load (40%, 60% and 80% of 1RM) for bench press and inclined leg press, with a 5-min recovery in between each repetition. A linear encoder was attached perpendicular to the movement, to the bar used for the exercises. Average power (AP), average force (AF), peak velocity (PV), distance (D) and time-to-peak velocity (tPV) were measured (MuscleLab software) during the concentric phase of the movements for each lift. Data were analysed using general linear models with repeated measures. The main findings were that SD reduced maximal grip (2.7%), bench press (11.2% AP, 3.3% AF and 9.4% PV) and leg press submaximal values (5.7% AP) with a trend for a reduction in AF (3.3% P = 0.06). Furthermore, RPE increased for measures of grip strength, leg and bench press during SD. Following a 1-h powernap (SD_N), values of grip and bench press improved to values similar in N, as did tiredness, alertness and sleepiness. There was a main effect for “load” on the bar for both bench and leg press where AP, AF, tPV values increased with load (P < 0.05) and PV decreased from the lightest to the heaviest load for both bench and leg press. An interaction of “load and condition” was present in leg press only, where the rate of change of AP is greater in the N than SD and SD_N conditions. In addition, for PV and tPV the rate of change was greater for SD_N than N or SD condition values. In summary, SD had a negative effect on grip strength and some components of bench and inclined leg press. The use of a 1-h power nap that ended 3 h before the “strength” assessment had a positive effect on weightlifting performance, subjective mood and ratings of tiredness.     

Local sleep homeostasis in the avian brain: convergence of sleep function in mammals and birds?

The function of the brain activity that defines slow wave sleep (SWS) and rapid eye movement (REM) sleep in mammals is unknown. During SWS, the level of electroencephalogram slow wave activity (SWA or 0.5-4.5 Hz power density) increases and decreases as a function of prior time spent awake and asleep, respectively. Such dynamics occur in response to waking brain use, as SWA increases locally in brain regions used more extensively during prior wakefulness. Thus, SWA is thought to reflect homeostatically regulated processes potentially tied to maintaining optimal brain functioning. Interestingly, birds also engage in SWS and REM sleep, a similarity that arose via convergent evolution, as sleeping reptiles and amphibians do not show similar brain activity. Although birds deprived of sleep show global increases in SWA during subsequent sleep, it is unclear whether avian sleep is likewise regulated locally. Here, we provide, to our knowledge, the first electrophysiological evidence for local sleep homeostasis in the avian brain. After staying awake watching David Attenborough's The Life of Birds with only one eye, SWA and the slope of slow waves (a purported marker of synaptic strength) increased only in the hyperpallium--a primary visual processing region--neurologically connected to the stimulated eye. Asymmetries were specific to the hyperpallium, as the non-visual mesopallium showed a symmetric increase in SWA and wave slope. Thus, hypotheses for the function of mammalian SWS that rely on local sleep homeostasis may apply also to birds.     

A HAT for sleep?: Epigenetic regulation of sleep by Tip60 in Drosophila

Sleep disturbances are common in neurodegenerative diseases such as Alzheimer disease (AD). Unfortunately, how AD is mechanistically linked with interference of the body’s natural sleep rhythms remains unclear. Our recent findings provide insight into this question by demonstrating that sleep disruption associated with AD is driven by epigenetic changes mediated by the histone acetyltransferase (HAT) Tip60. In this study, we show that Tip60 functionally interacts with the AD associated amyloid precursor protein (APP) to regulate axonal growth of Drosophila small ventrolateral neuronal (sLNv) pacemaker cells, and their production of neuropeptide pigment dispersing factor (PDF) that stabilizes appropriate sleep-wake patterns in the fly. Loss of Tip60 HAT activity under APP neurodegenerative conditions causes decreased PDF production, retraction of the sLNv synaptic arbor required for PDF release and disruption of sleep-wake cycles in these flies. Remarkably, excess Tip60 in conjunction with APP fully rescues these sleep-wake disturbances by inducing overelaboration of the sLNv synaptic terminals and increasing PDF levels, supporting a neuroprotective role for Tip60 in these processes. Our studies highlight the importance of epigenetic based mechanisms underlying sleep disturbances in neurodegenerative diseases like AD.     

Age-related changes in the association of sleep satisfaction with sleep quality and sleep–wake pattern

Sleep and Biological Rhythms - Age-specific relationship of sleep–wake pattern with night sleep satisfaction was examined to address a question of why sleep satisfaction does not accurately...     

A brief pre-exercise nap may alleviate physical performance impairments induced by short-term sustained operations with partial sleep deprivation – A field-based study

ABSTRACT

The purpose of the study was to evaluate the recuperative efficacy of pre-exercise napping on physical capacity after military sustained operations (SUSOPS) with partial sleep deprivation. Before and after a 2-day SUSOPS, 61 cadets completed a battery of questionnaires, and performed a 2-min lunges trial and a 3,000-m running time-trial. After the completion of SUSOPS, subjects were randomized to either a control [without pre-exercise nap (CON); n = 32] or a nap [with a 30-min pre-exercise nap (NAP); n = 29] group. SUSOPS enhanced perceived sleepiness and degraded mood in both groups. Following SUSOPS, the repetitions of lunges, in the CON group, were reduced by ~ 2.3%, albeit the difference was not statistically significant (p = 0.62). In the NAP group, however, the repetitions of lunges were increased by ~ 7.1% (p = 0.01). SUSOPS impaired the 3,000-m running performance in the CON group (~ 2.3%; p = 0.02), but not in the NAP group (0.3%; p = 0.71). Present results indicate, therefore, that a relatively brief pre-exercise nap may mitigate physical performance impairments ensued by short-term SUSOPS.     

Peritrophic membrane contribution to Bt Cry δ-endotoxin susceptibility in Lepidoptera and the effect of Calcofluor

In an effort to determine a reason for differing susceptibilities to Bacillus thuringiensis (Bt) Cry δ-endotoxins amongst lepidopteran species, the peritrophic membrane (PM), and a number of agents that target the PM, were investigated to determine their effect on the efficacy of Bt toxins. In particular Calcofluor is able to disrupt the PM that acts as a barrier to microorganisms. Although Bt toxins have been shown to traverse the PM in some lepidopteran species, new data shows that toxins can bind the PM. Lepidopteran larval PMs also vary in thickness and composition that may determine the passage of Bt toxins. In non-susceptible insects the toxin associates with PM proteins and frass and is thought to be retained by the PM and then excreted before binding to the exposed target midgut membrane. However, the addition of Calcofluor to Bt toxins at an LC₅₀ for the recipient species did not result in an increase in the efficacy of the toxin. It is evident that Calcofluor does disrupt the PM but the toxin preferentially binds PM fragments and is excreted instead of binding the exposed target midgut membrane, therefore having little toxic effect. This study therefore concludes that Calcofluor is not as suitable as other toxin enhancing agents such as chitinase.     

Influence of Bt-plants on soil biota and pleiotropic effect of δ-endotoxin-encoding genes

The critical review of experimental conclusions stating environmental safety of transgenic plants reveals that the methods and test materials employed in some studies were inadequate to the goals pursued. A large-scale application of transgenic Bt-plants may result in long-lasting negative impact on the environment. First, the cultivation of these plants leads to accumulation of Bt-toxins in soil. Second, the decomposition of transgenic plants takes significantly longer time compared to that of isogenic lines. Third, the biological activity of soils under transgenic crops is lower than in the control plots. The transfer of δ-endotoxin-encoding genes to the genome of agricultural crops affects simultaneously several entirely different traits of genetically modified plants, thus exerting pleiotropic effects. This gives rise to a paradoxical situation: the genetically engineered crops selected on the trait of resistance to herbivorous insects of the order Lepidoptera become more attractive for herbivores from the other order, Homoptera.     

The effect of motion sickness on the sleep–wake cycle in rats exposed to prenatal hypoxia

This study is a follow-up to our previous research of the phenomenology and mechanisms of motion sickness (MS) and its relationship with changes in the sleep–wake cycle (SWC). We report data on the effect of MS on the SWC in 30-day-old intact rats and those exposed to prenatal hypoxia on days 13 and 19 of gestation. In all animal groups, MS was shown to decrease significantly the waking time and increase that of paradoxical sleep (PS). A link between hypothalamic MS and SWC regulatory mechanisms was revealed, and the role of this teamwork in the development of the sopite syndrome, which may be a sole manifestation of MS in some animals and man, was suggested. It was established that hypoxic exposure on day 19 of gestation had a greater damaging effect on the thalamocortical sleep-regulating structures than that on day 13, when it is only the hypothalamic-hippocampal slow-sleep regulatory systems that were found to be affected. Against this background, MS appreciably suppresses the brain excitatory systems that maintain wakefulness (supposed to be the ascending reticular activating system) and enhances those activating systems that regulate PS. It is exactly prenatal hypoxic exposure of rats on day 19 of gestation that enabled demonstrating the role of the evolutionarily young thalamocortical system in PS control.     

Membrane partitioning of various δ-opioid receptor forms before and after agonist activations: The effect of cholesterol

Lipid rafts depicted as densely packed and thicker membrane microdomains, based on the dynamic clustering of cholesterol and sphingolipids, may help as platforms involved in a wide variety of cellular processes. The reasons why proteins segregate into rafts are yet to be clarified. The human delta opioid receptor (hDOR) reconstituted in a model system has been characterised after ligand binding by an elongation of its transmembrane part, inducing rearrangement of its lipid microenvironment [Alves, Salamon, Hruby, and Tollin (2005) Biochemistry 44, 9168-9178]. We used hDOR to understand better the correlation between its function and its membrane microdomain localisation. A fusion protein of hDOR with the Green Fluorescent Protein (DOR?) allows precise receptor membrane quantification. Here we report that (i) a fraction of the total receptor pool requires cholesterol for binding activity, (ii) G-proteins stabilize a high affinity state conformation which does not seem modulated by cholesterol. In relation to its distribution, and (iii) a fraction of DOR? is constitutively associated with detergent-resistant membranes (DRM) characterised by an enrichment in lipids and proteins raft markers. (iv) An increase in the quantity of DOR? was observed upon agonist addition. (v) This DRM relocation is prevented by uncoupling the receptor-G-protein interaction.     

The effect of enhancing environmental factors on the quality of patients’ sleep in a cardiac surgical intensive care unit

The aim of this study was to investigate the effect of enhancing environmental factors on the duration and quality of sleep among patients in a cardiovascular surgery intensive care unit (CSICU). This quasi-experimental study was conducted upon 100 patients. The experimental group received nursing interventions to control the environmental factors that negatively affect nocturnal sleep. Data also were collected using a form to assess the environmental factors and the Richards–Campbell Sleep Questionnaire in the morning of the second day after the operation. The difference between the groups was statistically significant in favor of the experimental group for eight of the environmental factors. Compared with that in the control group, the duration of sleep was longer (experimental, 6.30 h; control, 3.98 h) and the quality of sleep was higher (experimental, 66.57 units; control, 44.43 units) in the experimental group. We conclude that nursing interventions should be used to control the environmental factors that negatively affect nocturnal sleep in CSICUs.     

The Biosynthesis of δ-Aminolevulinic Acid in Chlorella

When autotrophically growing cultures of Chlorella are treated with levulinic acid, delta-aminolevulinic acid is excreted into the medium, providing a direct demonstration of alpha-aminolevulinic acid production in a green plant. Evidence is presented which indicates that alpha-aminolevulinic acid formation may be the the rate-controlling step of chlorophyll synthesis in Chlorella, and that control of the rate of alpha-aminolevulinic acid synthesis may be exerted at the level of production and breakdown of an enzyme which catalyzes its formation.     

Interleukin-1β enhances the effect of serum deprivation on rat annular cell apoptosis

Excessive apoptosis of disc cells is believed to play an important role in intervertebral disc (IVD) degeneration. It has been shown that interleukin-1β (IL-1β) is involved in the failure of disc matrix by suppressing the synthesis of matrix components and stimulating the expression of matrix metalloproteinases. However, whether IL-1β induces disc cell apoptosis is still unclear. The objective of this study was to investigate the effect of IL-1β on the apoptosis of rat annular cells cultured with or without serum supplement. First-passage rat annular cells were cultured with 0% or 10% fetal bovine serum (FBS) supplement and stimulated with 0, 10, 20 or 50 ng/ml IL-1β for 12, 24 or 48 h. Apoptotic incidences were quantified by flow cytometry, morphologic changes in apoptotic cells were visualized by Hoechst 33258 staining and phase-contrast microscopy, and caspase-3 activity was also determined. When rat annular cells were cultured with 10% FBS supplement, no significant changes in apoptotic incidences, apoptotic morphology and caspase-3 activity were observed even when cells were stimulated with 50 ng/ml IL-1β for 48 h. In contrast, serum deprivation for 24 h led to an increase in apoptotic incidences, the number of apoptotic nuclei and caspase-3 activity, and IL-1β significantly increased the effects of serum deprivation in a dose-dependent manner. Our results indicate that IL-1β alone is not a sufficient stimulus to induce disc cell apoptosis and that in order to suppress disc cell apoptosis, improving the nutrient supply to the disc may be more effective than antagonizing the adverse effects of IL-1β.     

The effect of exogenous δ-aminolaevulinate on rat liver haem and cytochromes

The activity of delta-aminolaevulinate synthetase is generally regarded as rate-limiting for hepatic haem biosynthesis. It has been suggested that cytochrome synthesis may also be regulated by changes in delta-aminolaevulinate synthetase activity. This hypothesis was studied by injecting product, delta-aminolaevulinate, into adult rats over a 4-240h period. The concentrations of hepatic mitochondrial cytochromes a, b, c and c(1) were unchanged by treatment with delta-aminolaevulinate, allylisopropylacetamide or phenobarbital. In control animals, total microsomal haem content equalled the sum of cytochromes b(5) plus P-450. After delta-aminolaevulinate administration the total amount of microsomal haem, measured as the pyridine haemochromogen, exceeded these components, indicating the formation of a ;free' haem pool. Haem synthesis does not appear rate-limiting for hepatic cytochrome synthesis in the adult rat.     

Expression of estrogen receptor α and β in rat astrocytes in primary culture: effects of hypoxia and glucose deprivation

Estrogen replacement therapy could play a role in the reduction of injury associated with cerebral ischemia in vivo, which could be, at least partially, a consequence of estrogen influence of glutamate buffering by astrocytes during hypoxia/ischemia. Estrogen exerts biological effects through interaction with its two receptors: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which are both expressed in astrocytes. This study explored effects of hypoxia and glucose deprivation (HGD), alone or followed by 1 h recovery, on ERα and ERβ expression in primary rat astrocyte cultures following 1 h exposure to: a) 5 % CO(2) in air (control group-CG); b) 2 % O(2)/5 % CO(2) in N(2) with glucose deprivation (HGD group-HGDG); or c) the HGDG protocol followed by 1 h CG protocol (recovery group-RG). ERα mRNA expression decreased in HGDG. At the protein level, full-length ERα (67 kDa) and three ERα-immunoreactive protein bands (63, 60 and 52 kDa) were detected. A significant decrease in the 52 kDa band was seen in HGDG, while a significant decrease in expression of the full length ERα was seen in the RG. ERβ mRNA and protein expression (a 54 kDa single band) did not change. The observed decrease in ERα protein may limit estrogen-mediated signalling in astrocytes during hypoxia and recovery.     

Biosynthesis of δ-aminolevulinic acid in Rhodopseudomonas sphaeroides

The biosynthesis of δ-aminolevulinic acid was investigated in three strains of Rhodopseudomonas sphaeroides. A wild-type strain (NCIB 8253) possessed both δ-aminolevulinic acid synthetase and γ,δ-dioxovaleric acid transaminase in the cytoplasmic and membrane cell fractions. δ-Aminolevulinic acid synthetase activities were not detected in extracts of mutant strains H5 and H5D. However, γ,δ-dioxovaleric acid transaminase was found in the cytoplasmic and membrane fractions of these latter two strains. Strain H5 required exogenously added δ-aminolevulinic acid for growth and bacteriochlorophyll synthesis. Strain H5D did not require this compound for growth and bacteriochlorophyll synthesis. γ,δ-Dioxovaleric acid added in the growth medium did not support the growth of H5, although it was actively transported into the cells. Addition of γ,δ-dioxovaleric acid to the growth medium did not enhance the growth of either the wild-type or H5D strains. These results indicate that ALA synthetase is not required for growth and bacteriochlorophyll synthesis in H5D and that γ,δ-dioxovaleric acid is probably not an intermediate in the formation of δ-aminolevulinic acid in the strains of Rhodopseudomonas sphaeroides studied. In strain H5D another pathway may function in the formation of δ-aminolevulinic acid other than that catalyzed by δ-aminolevulinic acid synthetase or γ,δ-dioxovaleric acid transaminase.