Differential effects of retinal degeneration on sleep and wakefulness responses to short light-dark cycles in albino mice.

This study characterizes the different response patterns of sleep and wakefulness (W) to short light-dark (LD) cycles in albino mice and examines whether retinal degeneration resulting from prolonged bright light treatment and/or rd/rd mutation alters such response patterns. Eight young male Institute for Cancer Research (ICR) mice with normal eyes, seven young male rd/rd Friend Virus B type (FVB) mice, six young ICR and five young rd/rd FVB mice receiving 48-h bright light treatment, and five older rd/rd FVB mice were implanted with skull and muscle electrodes to record sleep and W. All the mice were maintained in 12-h-12-h LD cycles at baseline and received 2 days of short LD cycle treatment, which included 5-min-5-min LD cycles for a total of 24 cycles presented 4h after lights-on and again 4h after lights-off. All the five mouse groups maintained photo-entrainment of sleep and W rhythms at the baseline and showed a preference for paradoxical sleep (PS) occurrence in the 5-min dark period and non-rapid eye movement sleep (NREMS) in the 5-min light period and a brief alerting effect of light onset on experimental days. Retinal degeneration rising from bright light treatment and/or genetic mutation failed to eliminate or reduce the response of PS and NREMS to short LD cycles, although it enhanced the LD contrast of W, i.e., bright light treatment prolonged the alerting effect of light and the rd mutation increased the suppressing effect of the dark on W. These results suggest that sleep responses to short LD cycles and the brief alerting effect of light were independent of the photoreceptors in the outer retina. Furthermore, the residual photoreceptors in the outer retina and/or the photosensitive cells in the inner retina may actively modulate the effect of light and dark signals on W.

[18F]-Fluorodeoxyglucose positron emission tomography in children with neurofibromatosis type 1 and plexiform neurofibromas: correlation with malignant transformation.

The objective of this study was to investigate the predictive value of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) in detecting malignant transformation of plexiform neurofibromas in children with neurofibromatosis type 1 (NF1). An electronic search of the medical records was performed to determine patients with NF1 who had undergone FDG-PET for plexiform neurofibroma between 2000 and 2011. All clinical, radiologic, pathology information and operative reports were reviewed. Relationship between histologic diagnosis, radiologic features and FDG-PET maximum standardized uptake value (SUV(max)) was evaluated. This study was approved by the Institutional Review Board of our institution. 1,450 individual patients were evaluated in our Multidisciplinary Neurofibromatosis Program, of whom 35 patients underwent FDG-PET for suspected MPNST based on change or progression of clinical symptoms, or MRI findings suggesting increased tumor size. Twenty patients had concurrent pathologic specimens from biopsy/excision of 27 distinct lesions (mean age 14.9 years). Pathologic interpretation of these specimens revealed plexiform and atypical plexiform neurofibromas (n = 8 each), low grade MPNST (n = 2), intermediate grade MPNST (n = 4), high grade MPNST (n = 2), GIST (n = 1) and non-ossifying fibroma (n = 1). SUV(max) of plexiform neurofibromas (including typical and atypical) was significantly different from MPNST (2.49 (SD = 1.50) vs. 7.63 (SD = 2.96), p < 0.001). A cutoff SUV(max) value of 4.0 had high sensitivity and specificity of 1.0 and 0.94 to distinguish between PN and MPNST. FDG-PET can be helpful in predicting malignant transformation in children with plexiform neurofibromas and determining the need for biopsy and/or surgical resection.

An open-access, very-low-field MRI system for posture-dependent 3He human lung imaging.

We describe the design and operation of an open-access, very-low-field, magnetic resonance imaging (MRI) system for in vivo hyperpolarized 3He imaging of the human lungs. This system permits the study of lung function in both horizontal and upright postures, a capability with important implications in pulmonary physiology and clinical medicine, including asthma and obesity. The imager uses a bi-planar B(0) coil design that produces an optimized 65 G (6.5 mT) magnetic field for 3He MRI at 210 kHz. Three sets of bi-planar coils produce the x, y, and z magnetic field gradients while providing a 79-cm inter-coil gap for the imaging subject. We use solenoidal Q-spoiled RF coils for operation at low frequencies, and are able to exploit insignificant sample loading to allow for pre-tuning/matching schemes and for accurate pre-calibration of flip angles. We obtain sufficient SNR to acquire 2D 3He images with up to 2.8mm resolution, and present initial 2D and 3D 3He images of human lungs in both supine and upright orientations. 1H MRI can also be performed for diagnostic and calibration reasons.

The effect of scheduled forced wheel activity on body weight in male F344 rats undergoing chronic circadian desynchronization.

OBJECTIVE: To examine whether scheduled forced wheel activity counteracts the increased body weight gain in rats undergoing chronic circadian desynchronization induced by repeated 12-h shifts in the light-dark cycle. DESIGN: Four age- and body weight-matched groups of adult male F344 rats were subjected to 12-h intermittent forced wheel activity daily (2.2 km/day). Each group had the following schedule for 13 weeks: a fixed schedule of a daily 12:12-h light-dark cycle and activity training (WF); a fixed light-dark cycle and 12-h shifts twice a week in activity training (WS); 12-h shifts twice a week in the light-dark cycle and a fixed schedule of activity training (LSWF); and 12-h shifts twice a week in both the light-dark cycle and activity training (LSWS). Two additional age- and body weight-matched sedentary rat groups were selected from our database: one was maintained on a fixed light-dark cycle (LC) and the other was subjected to 12-h shifts twice a week in the light-dark cycle (LS). RESULTS: The four rat groups that were exercised showed different response patterns of the daily body temperature rhythm to different combinations of forced activity and lighting schedules. Their food intake was more than that of the two sedentary rat groups, but their body weight was comparable with that of the LC rats and less than that of the LS rats during the forced activity period. The LSWS rats were heavier than the WF and WS rats in the first and second months of the experimental treatment, but their body weight was comparable with that of the WS and WF rats in the third month. CONCLUSION: Forced activity was effective in reducing the body weight gain in chronic circadian desynchronization that was induced by repeated shifts in the light-dark cycle, although such an effect might become significant only after some time.

Interstitial gas and density segregation of vertically vibrated granular media.

We report experimental studies of the effect of interstitial gas on mass-density segregation in a vertically vibrated mixture of equal-sized bronze and glass spheres. Sufficiently strong vibration in the presence of interstitial gas induces vertical segregation into sharply separated bronze and glass layers. We find that the segregated steady state (i.e., bronze or glass layer on top) is a sensitive function of gas pressure and viscosity, as well as vibration frequency and amplitude. In particular, we identify distinct regimes of behavior that characterize the change from bronze-on-top to glass-on-top steady state.

A System for Open-Access He Human Lung Imaging at Very Low Field.

We describe a prototype system built to allow open-access very-low-field MRI of human lungs using laser-polarized (3)He gas. The system employs an open four-coil electromagnet with an operational B(0) field of 4 mT, and planar gradient coils that generate gradient fields up to 0.18 G/cm in the x and y direction and 0.41 G/cm in the z direction. This system was used to obtain (1)H and (3)He phantom images and supine and upright (3)He images of human lungs. We include discussion on challenges unique to imaging at 50 -200 kHz, including noise filtering and compensation for narrow-bandwidth coils.

3He lung imaging in an open access, very-low-field human magnetic resonance imaging system.

The human lung and its functions are extremely sensitive to gravity; however, the conventional high-field magnets used for most laser-polarized (3)He MRI of the human lung restrict subjects to lying horizontally. Imaging of human lungs using inhaled laser-polarized (3)He gas is demonstrated in an open-access very-low-magnetic-field (<5 mT) MRI instrument. This prototype device employs a simple, low-cost electromagnet, with an open geometry that allows variation of the orientation of the imaging subject in a two-dimensional plane. As a demonstration, two-dimensional lung images were acquired with 4-mm in-plane resolution from a subject in two orientations: lying supine and sitting in a vertical position with one arm raised. Experience with this prototype device will guide optimization of a second-generation very-low-field imager to enable studies of human pulmonary physiology as a function of subject orientation.

Interaction between light-dark cycles and circadian rhythm on sleep and wakefulness in albino rats.

This study investigated the role of the circadian phase in modulating the effect of short light-dark cycles (LDc) on sleep and wakefulness. Six male albino rats of the Sprague-Dawley strain were implanted with electrodes for standard electrophysiological recordings performed during baseline (12 - 12 h LDc), short LDc treatment, and recovery (12 - 12 h LDc) for 4 days each. In the short LDc treatment, 15 - 15 min LDc were applied, respectively, in mid-periods of inactive and active phases to maintain an entrained circadian rhythm. The results showed that the 15 - 15 min LD ratio of both non-rapid eye movement sleep (NREM) and paradoxical sleep (PS) did not vary with the circadian phase. In contrast, changes in both the NREM and PS amounts in the short LDc treatment varied with the circadian phase. It is argued in the Discussion section that the circadian phase-related changes in the sleep amount did not result from the circadian rhythm effect but from the interactions between the habitual 24 h lighting schedule and the habitual LD distribution of the sleep and wakefulness amounts. On the other hand, this study found that both waking (W) and PS response to short LDc varied with time courses. The 15 min dark period strongly enhanced the W time only when it occurred for the first time in the inactive phase while it consistently facilitated PS across the remaining time periods in both the active and inactive phases. Furthermore, a residual effect of short LDc on PS was revealed in this study. Compared to the baseline, the 12 - 12 h LD ratio of PS was significantly decreased during recovery compared to the short LDc treatment.

Selection of valid and reliable EEG features for predicting auditory and visual alertness levels.

A selection procedure with three rules, high efficiency, low individual variability, and low redundancy, was developed to screen electroencephalogram (EEG) features for predicting behavioral alertness levels. A total of 24 EEG features were derived from temporal, frequency spectral, and statistical analyses. Behavioral alertness levels were quantified by correct rates of performance on an auditory and a visual vigilance task, separately. In the auditory task study, a subset of three EEG features, the relative spectral amplitudes in the alpha (alpha%, 8-13 Hz) and theta (theta%, 4-8 Hz) bands, and the mean frequency of the EEG spectrum (MF), was found to be the best combination for predicting the auditory alertness level. In the visual task study, the mean frequency of the beta band (Fbeta, 13-32 Hz) was the only EEG feature selected. The application of an averaging subwindow procedure within a moving time window to EEG analysis increased the predictive power of EEG features and decreased the disturbing effect of movement artifacts on the EEG data.

Staurosporine inhibits the proliferation, alters the cell cycle distribution and induces apoptosis in HT-29 human colon adenocarcinoma cells.

Staurosporine (ST), a potent inhibitor of protein kinase C (PKC), was evaluated for its effect on the proliferation of HT-29 colon adenocarcinoma cells; PKC is associated with increased colon cell proliferation. ST inhibited cell proliferation in a time- and concentration-dependent manner by up to 90%. It also blocked the G2/M phase of the cell cycle and induced classical apoptosis (sub-diploid peak on flow cytometry, DNA ladder, and typical morphological changes). The kinetics of these changes suggest that low ST concentrations (2-20 nM) may act via a different mechanism from higher (100-1000 nM) ones. The role of ST, which is currently evaluated as an antitumor agent, in colon cancer requires further evaluation.

The anti-proliferative effect of sulindac and sulindac sulfide on HT-29 colon cancer cells: alterations in tumor suppressor and cell cycle-regulatory proteins.

Nonsteroidal anti-inflammatory drugs lower the incidence of and mortality from colon cancer. Sulindac reduces the number and size of polyps in patients with familial adenomatous polyposis. We have shown that sulindac and sulindac sulfide reversibly reduce the proliferation rate of HT-29 colon cancer cells, alter their morphology, induce them to accumulate in the G0/G1 phase of the cell cycle, and sulindac sulfide induces cell death by apoptosis. In this study we confirmed that sulindac and sulindac sulfide prevent HT-29 cells from progressing from the G0/G1 into the S phase. This block in cell cycle progression is associated with an initial rise, then an abrupt decrease in the levels of p34cdc2 protein. Sulindac and sulindac sulfide decrease the levels of mitotic cyclins, induce the levels of p21WAF-1/cip1, and reduce the total levels of pRB, with a relative increase in the amount of the underphosphorylated form of pRB in a time- and concentration-dependent manner. In addition, these compounds reduce the levels of mutant p53. These responses are not associated with intestinal cell differentiation and occur independent of the ability of these compounds to induce apoptosis. We conclude that sulindac and sulindac sulfide reduce the levels of major components of the molecular cell cycle machinery and alter the levels of several tumor suppressor proteins in a manner consistent with cell cycle quiescence. These mechanisms may be operative in vivo to account, in part, for the anti-neoplastic effects of these compounds.

Sleep deprivation in the rat: XX. Differences in wake and sleep temperatures during recovery.

We examined the relationship between wake and sleep peritoneal temperature (T(ip)) during recovery from short-term (five rats, 5 days of deprivation) and long-term (nine rats, 14-21 days) total sleep deprivation (TSD). Mammalian body temperature normally declines in the passage from wakefulness to sleep. Recovery from TSD featured reductions of the typical wake-sleep T(ip) differences. Previous studies from our laboratory have shown that chronic TSD in the rat produces a progressive rise in energy production and an initial rise in wake T(ip), followed by a later fall in T(ip) to below baseline that becomes more acute as death becomes imminent. During recovery from both short-term TSD (wherein pre-recovery wake T(ip) was still above baseline) and long-term TSD (wherein pre-recovery wake T(ip) had fallen to below baseline), wake T(ip) and energy production quickly returned towards baseline. On the first recovery day, both short- and long-term TSD rats showed mean non-rapid eye movement (NREM) and paradoxical sleep (PS) T(ip) values that were slightly, although not significantly, above mean wake T(ip). In short-term TSD rats, wake-NREM and wake-PS T(ip) differences were reduced from baseline significantly (p < 0.0025) on the first recovery day and nonsignificantly on the remaining three recovery days. In long-term TSD rats, wake-NREM and wake-PS T(ip) differences were significantly (p < 0.001) reduced from baseline on the first four recovery day block. On the last four recovery day block, wake-sleep T(ip) differences tended to return toward baseline. Hypothalamic wake-sleep temperature differences in long-term TSD rats showed similar reductions during recovery. The reduction of wake-sleep temperature differences in recovery does not support either energy reduction or cooling functions for sleep.

Sulindac sulfide, an aspirin-like compound, inhibits proliferation, causes cell cycle quiescence, and induces apoptosis in HT-29 colon adenocarcinoma cells.

Nonsteroidal antiinflammatory drugs (NSAIDs), have cancer preventive and tumor regressive effects in the human colon. They lower the incidence of and mortality from colorectal cancer and sulindac reduces the number and size of polyps in patients with familial adenomatous polyposis. We studied the effect of sulindac, and its metabolite sulindac sulfide, on the proliferation of HT-29 colon adenocarcinoma cells. Both compounds reduced the proliferation rate of these cells, changed their morphology, and caused them to accumulate in the G0/G1 phase of the cell cycle. These responses were time- and concentration-dependent and reversible. In addition, these compounds reduced the level and activity of several cyclin-dependent kinases (cdks), which regulate cell cycle progression. Sulindac and sulindac sulfide also induced apoptosis in these cells at concentrations that affected their proliferation, morphology, and cell cycle phase distribution. Sulindac sulfide was approximately sixfold more potent than sulindac in inducing these cellular responses. Our results indicate that inhibition of cell cycle progression and induction of apoptotic cell death contribute to the anti-proliferative effects of sulindac and sulindac sulfide in HT-29 cells. These findings may be relevant to the cancer preventive and tumor regressive effects of these compounds in humans.

Effects of chronic sleep deprivation on central cholinergic receptors in rat brain.

Rats subjected to chronic total sleep deprivation (TSD) by the disk-over-water method have shown very large, sustained rebounds in paradoxical sleep (PS) (also known as REM sleep). Other studies have indicated that cholinergic mechanisms are involved in the instigation and maintenance of PS. Hypothetically, the large PS rebounds could be mediated by an upregulation of cholinergic receptors during TSD. To evaluate this hypothesis, regional brain cholinergic receptors were compared in rats subjected to 10-day TSD by the disk-over-water method (TSD rats), yoked control (TSC) rats which received the same physical stimulation but with much smaller reductions in sleep, and home cage control (HCC) rats. L-[3H]nicotine and [3H]quinuclidinyl benzilate were used as specific cholinergic radioligands for nicotinic and muscarinic receptor binding assays, respectively. Nicotinic receptor binding was not significantly different among groups for any of the brain regions assayed, including frontal cortex, parietal cortex, thalamus, amygdala, hippocampus, anterior hypothalamus, posterior hypothalamus, caudate, limbic system (including septal area, olfactory tubercle, and nucleus accumbens), midbrain, pons, and medulla. Thus, there was no evidence that changes in nicotinic receptors mediate the PS rebounds. For muscarinic receptor binding, TSD rats differed significantly from control rats only in showing a higher binding affinity than TSC rats in the limbic system and a lower binding density than HCC rats in the hippocampus. On the other hand, significant differences in muscarinic receptor binding sites between rats selectively deprived of PS and their yoked controls were found only for the septal area.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chronic total sleep deprivation on central noradrenergic receptors in rat brain.

The effect of chronic total sleep deprivation (TSD) on the regulation of central noradrenergic receptors was evaluated. Rats were subjected to 10 days of TSD by the disk-over-water method. As in previous TSD studies, these rats showed greater increases in food intake and energy expenditure and greater eventual declines in waking body temperature than their yoked-control (TSC) rats. After sacrifice, alpha 1-, alpha 2-, and beta-adrenoceptors were determined in 11 brain regions using radioligand binding assays with [3H]prazosin, [3H]rauwolscine, and 125I-iodocyanopindolol, respectively. Adrenoceptor density and affinity values were significantly different among TSD, TSC, and normally caged control rat groups only for the cerebellum, which showed higher alpha 2-binding density concomitant with lower affinity and lower beta-binding density than cage control rats. Such changes are attributable to apparatus or stimulus effects common to TSD and TSC rats. Given the absence of firm evidence for a TSD-induced downregulation of central noradrenergic receptors, the present results offer no support for the hypothesis of Siegel and Rogawski that a major function of paradoxical sleep is to upregulate these receptors.

Changes in sleep patterns by intralaminar thalamic microinjection of fluoxetine in rats.

Sleep patterns were investigated in rats by analysis of EEG recorded for 6 hours following fluoxetine or saline (control) microinjection into the centromedial intralaminar thalamus (CIT) at either 9:30 AM or 1:30 PM, 4 or 8 hours after lights on, respectively. The treatment of fluoxetine at 9:30 AM did not affect any sleep patterns. In contrast, fluoxetine significantly suppressed total paradoxical sleep (PS) time and the number of PS episodes during the second and third hour after administration at 1:30 PM. In addition, microinjection of fluoxetine produced an apparent enhancement of the duration of slow wave sleep (SWS) episodes and a small non-significant increase in total SWS time. On the other hand, no obvious changes in the basal sleep-wakefulness pattern were found between the two saline-treated control groups. These results indicate that CIT microinjection of fluoxetine at different time points acts differentially in sleep patterns and suggest that CIT may be one of the action sites for peripherally administered fluoxetine to alter sleep patterns.

Sleep deprivation in the rat: XVI. Effects in a light-dark cycle.

To avoid a possible confound between the effects of sleep loss and disturbed circadian rhythms in previous studies of total sleep deprivation (TSD) by the disk-over-water method, TSD rats and their yoked control (TSC) rats had been maintained in constant light both before and during the experiment. With circadian rhythms of both groups flattened by constant light, group differences in outcome measures could be attributed to sleep loss. However, the constant light control entailed the possibility that the sleep loss effects might obtain only in constant light. To evaluate this possibility, three TSD-TSC rat pairs maintained on a 12 hour light: 12 hour dark (LD) schedule were studied. TSC rats showed only minor changes during the deprivation period. As in previous studies, TSD rats showed increased food intake; decreased weight; increased energy expenditure; debilitated appearance; lesions on the tail and paws; an initial increase followed by a large decrease in body temperature; impending death; and recovery sleep, which featured large, selective, sustained rebounds of paradoxical sleep and a reversal of all observed TSD-induced changes. Thus, TSD produced the same changes during an LD schedule as during constant light. The amplitude of the diurnal body temperature rhythm declined over the course of TSD and then almost completely recovered during the first day of recovery sleep. The decline was interpreted as the result of deprivation-induced thermoregulatory changes.

Improved liquid-chromatographic method for determination of serum cortisol.

We describe a specific and precise method for measuring concentrations of cortisol in serum or plasma by liquid chromatography. Cortisol, together with an internal standard, equilenin, is extracted from 1 mL of serum or plasma and analyzed isocratically on a reversed-phase column with a mobile phase of acetonitrile/phosphate buffer (30/70, by vol.), at a flow rate of 2.0 mL/min. The eluted cortisol is detected by its absorption at 254 nm and quantitated by peak height measurements. Each analysis requires no longer than 15 min at the optimum column temperature of 50 degrees C. The lower limit of detection for cortisol is about 2 ng/sample for a standard solution; sensitivity is routinely 5 micrograms/L of serum. Analytical recoveries exceeded 95%, with good day-to-day precision (coefficients of variation between 4 and 7%). Of more than 50 drugs and steroids tested for possible interference, only the steroids cortisone, prednisone, and prednisolone may interfere with the analysis of cortisol.