Intraperitoneal administration of docosahexaenoic acid for 14days increases serum unesterified DHA and seizure latency in the maximal pentylenetetrazol model.

Docosahexaenoic acid (DHA) is an omega-3 polyunsaturated fatty acid (n-3 PUFA) which has been shown to raise seizure thresholds following acute administration in rats. The aims of the present experiment were the following: 1) to test whether subchronic DHA administration raises seizure threshold in the maximal pentylenetetrazol (PTZ) model 24h following the last injection and 2) to determine whether the increase in seizure threshold is correlated with an increase in serum and/or brain DHA. Animals received daily intraperitoneal (i.p.) injections of 50mg/kg of DHA, DHA ethyl ester (DHA EE), or volume-matched vehicle (albumin/saline) for 14days. On day 15, one subset of animals was seizure tested in the maximal PTZ model (Experiment 1). In a separate (non-seizure tested) subset of animals, blood was collected, and brains were excised following high-energy, head-focused microwave fixation. Lipid analysis was performed on serum and brain (Experiment 2). For data analysis, the DHA and DHA EE groups were combined since they did not differ significantly from each other. In the maximal PTZ model, DHA significantly increased seizure latency by approximately 3-fold as compared to vehicle-injected animals. This increase in seizure latency was associated with an increase in serum unesterified DHA. Total brain DHA and brain unesterified DHA concentrations, however, did not differ significantly in the treatment and control groups. An increase in serum unesterified DHA concentration reflecting increased flux of DHA to the brain appears to explain changes in seizure threshold, independent of changes in brain DHA concentrations.

An unusual presentation of osteoblastoma of the maxilla: A case report.

This report presents a rare case of maxillary osteoblastoma in a 17-year-old female. The patient presented with dull pain and facial asymmetry inferior to the left zygoma. An intraoral examination found a painless swelling on the buccal gingival tissue in the left posterior maxilla. Panoramic radiographs and multidetector computed tomographic images revealed an ill-defined, non-corticated, mixed attenuating entity of osseous density located within the left posterior maxilla apical to the left maxillary molars. The entity exhibited a heterogeneous internal structure with a fine granular appearance, and the periphery showed a partial hypo-attenuating rim along the antero-medial aspect. Expansion of the left posterior maxilla accompanied with displacement of the left maxillary sinus floor was noted. External root resorption of the first and second molars was noted, as well as postero-superior displacement of the third molar. The histopathologic diagnosis of the biopsy was osteoblastoma. Complete excision of the tumor was performed.

Statistical properties of sleep-wake behavior in the rat and their relation to circadian and ultradian phases.

STUDY OBJECTIVES: To examine the statistical characteristics of short-term sleep-wake architecture and to evaluate their dependence on ultradian and circadian phase. DESIGN: Observational, time series. SETTING: Laboratory. PARTICIPANTS: Ten male adult Sprague-Dawley rats. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: States of wakefulness (WAKE), rapid eye movement sleep (REM) and nonrapid eye movement sleep (NREM) were recorded in 5-sec epochs over 7 consecutive days. State bout durations were analyzed using parametric regression of survival curves, comparing exponential, biexponential, and power law models. WAKE survival curves were best fit by biexponential models, suggesting that there are two statistically distinct stochastic mechanisms generating two types of WAKE--"brief" WAKE and "long" WAKE. Exponential time constants varied as a function of circadian and ultradian phase, with "long" WAKE showing the largest effect. NREM survival curves exhibited biexponential and monoexponential distributions in light and dark, respectively, with weak effects of ultradian phase. REM survival curves approximated a monoexponential distribution that varied with circadian but not ultradian phase. χ(2) analysis was used in a three-state Markov model to evaluate whether conditional state transition probabilities exhibit the property of first-order dependence. This was partially confirmed, but only after accounting for heterogeneity associated with circadian and ultradian phase. However, there was evidence of residual second-order dependence indicating that additional sources of statistical heterogeneity may remain to be identified. CONCLUSIONS: Sleep-wake state is regulated over short timescales by stochastic mechanisms. When the major sources of heterogeneity are taken into account, including two-component WAKE and NREM states, the sleep-wake system of the rat behaves, to a reasonable approximation, as a Markovian system that is modulated over ultradian and circadian timescales.

Sleep-wake behavior in the rat: ultradian rhythms in a light-dark cycle and continuous bright light.

Ultradian rhythms are a prominent but little-studied feature of mammalian sleep-wake and rest-activity patterns. They are especially evident in long-term records of behavioral state in polyphasic animals such as rodents. However, few attempts have been made to incorporate ultradian rhythmicity into models of sleep-wake dynamics, and little is known about the physiological mechanisms that give rise to ultradian rhythms in sleep-wake state. This study investigated ultradian dynamics in sleep and wakefulness in rats entrained to a 12-h:12-h light-dark cycle (LD) and in rats whose circadian rhythms were suppressed and free-running following long-term exposure to uninterrupted bright light (LL). We recorded sleep-wake state continuously for 7 to 12 consecutive days and used time-series analysis to quantify the dynamics of net cumulative time in each state (wakefulness [WAKE], rapid eye movement sleep [REM], and non-REM sleep [NREM]) in each animal individually. Form estimates and autocorrelation confirmed the presence of significant ultradian and circadian rhythms; maximum entropy spectral analysis allowed high-resolution evaluation of multiple periods within the signal, and wave-by-wave analysis enabled a statistical evaluation of the instantaneous period, peak-trough range, and phase of each ultradian wave in the time series. Significant ultradian periodicities were present in all 3 states in all animals. In LD, ultradian range was approximately 28% of circadian range. In LL, ultradian range was slightly reduced relative to LD, and circadian range was strongly attenuated. Ultradian rhythms were found to be quasiperiodic in both LD and LL. That is, ultradian period varied randomly around a mean of approximately 4 h, with no relationship between ultradian period and time of day.