Effect of continuous positive airway pressure treatment on the subsequent EEG spectral power and sleepiness over sustained wakefulness in patients with obstructive sleep apnea-hypopnea syndrome

OBJECTIVE

To determine whether sleepiness and its evolution over sustained wakefulness could be reversed by nasal continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

Twelve OSAHS patients underwent three 32-h sessions of study: one before CPAP therapy (T0), the second (T3) and the third (T6), respectively, after 3 and 6 months of therapy. Each session included one night of sleep followed by 24 h of sustained wakefulness, during which EEG recordings and subjective ratings were performed every hour.

RESULTS

The waking EEG in treated OSAHS patients was partially improved after 3 months of CPAP and their subjective complaint of sleepiness was normalized after 6 months. Theta power (3.9-7.8 Hz) was decreased as well as its time course during the diurnal period but beta power (12.7-29.2 Hz) remained higher.

CONCLUSIONS

CPAP partially reverses waking EEG abnormalities in OSAHS patients with reduced theta activity after 3 months and removes the subjective complaint of sleepiness after 6 months. Nevertheless, the persistence of increased beta activity in treated patients suggests that efforts to stay awake remain strong after CPAP treatment.

SIGNIFICANCE

CPAP influences the EEG's time course over sustained wakefulness in a frequency-specific manner in OSAHS patients.

Severity of obstructive sleep apnoea/hypopnoea syndrome and subsequent waking EEG spectral power

It is well known that most patients with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) suffer sleepiness, although the underlying mechanisms of this relationship remain unclear. The present study examined the relationship between nocturnal variables and the subsequent waking electroencephalogram (EEG), in order to determine if sleepiness was related to OSAHS severity and due to sleep fragmentation or to nocturnal hypoxaemia. In total, 12 moderate-to-severe OSAHS patients underwent a total sleep night followed by a 24-h period of sustained wakefulness where the waking EEG was measured every hour. The results showed that alpha (7.9-12.6 Hz) and beta (12.7-29.2 Hz) activities were strongly related to OSAHS severity, mainly reflected by the apnoea index. Moreover, spectral power in most of the waking EEG components was significantly correlated with nocturnal hypoxaemia indices, namely alpha and beta activity when hypoxaemia becomes severe. However, no correlation was found between the waking EEG and sleep fragmentation parameters. In conclusion, the present results suggest that the difficulty in maintaining an optimal level of alertness, reflected by a higher activity in awake alpha and beta bands (7.9-29.2 Hz) in obstructive sleep apnoea/hypopnoea syndrome, was better explained by: 1) the apnoea as opposed to the hypopnoea index; and 2) nocturnal hypoxaemia as opposed to sleep fragmentation.

Are OSAS patients impaired in their driving ability on a circuit with medium traffic density?

OBJECTIVES

Many studies have demonstrated that patients with Obstructive Sleep Apnea Syndrome (OSAS), a very common sleep-related breathing disorder, are usually impaired in their driving ability because of decreased sleep quality. However, most of the simulation procedures in laboratories are designed to create monotonic conditions with low traffic density, if any, thereby leading to a dramatic decrease in performance in OSAS patients because of the lack of stimulation. The aim of this study was therefore to evaluate driving abilities in OSAS patients involved in a driving simulation task with medium traffic density, in order to replicate as far as possible real world conditions. The behavioral and physiological attributes likely to predict driving performance in these patients were also investigated.

METHODS

After a normal night of sleep, 12 OSAS patients and 8 healthy controls performed 6 driving sessions during a 24-h period of sustained wakefulness. Driving performances (speed, lateral position, distances...) were measured and correlated to sleep parameters and to a waking EEG recorded during the task.

RESULTS

Compared to controls, patients showed difficulties in speed adjustment. However, they maintained longer inter-vehicle distances, including during overtaking. Their waking EEG, while driving, showed increased spectral power in theta (3.9-7.8Hz) but also in beta (12.7-29.2Hz) activity, alpha power (7.9-12.6Hz) being increased in both groups due to sustained wakefulness. Poor sleep indices were correlated to increased theta and beta activities, as well as to more cautious behavior.

DISCUSSION

In medium traffic density conditions, driving performance in OSAS patients remained at near normal levels, but with more cautious behavior than controls. This could be the result of a bigger effort to stay awake, as suggested by an increased beta activity in these patients.

Toxoplasma gondii infection in horses. A review

This review updates those written by Dubey and Beattie in 1988 (1988a) and by Tenter et al in 2000, on pathological and epidemiological aspects of Toxoplasma infection in horses. Under natural conditions, seroprevalence may variate from 0% up to 90%. This wide variation may be due to the sensitivity of the serological methods, to the age of animals, to the geographical area, and even to the hygienic condition of the farms and farm management. With few exceptions, horses are considered one of the less sensitive specie to the pathogenic effect of Toxoplasma gondii. In fact, neither under experimental nor under natural condition a genuine pathologic picture related to the toxoplasmic infection has been described. In one occasion the organism has been isolated from an eye condition and in others a connection between a higher frequency of unspecified pathological conditions and a positive response to serological test for Toxoplasma has been speculated. Diaplacental transmission and the following abortion have been only occasionally reported, and at least in one case in a quite trustworthy way, therefore it must be considered possible, though rare. Although infection of humans due to the consumption of horse meat has never been reported, the existence of a possible risk arouses by the demonstration of the presence of parasite stages in either naturally or experimentally infected horses, which resulted to be infective for mice and/or cats.

Tick-borne diseases (TBDs) of dairy cows in a Mediterranean environment: a clinical, serological, and hematological study

A longitudinal study of tick-borne diseases (TBDs) in Southern Italy was carried out by monitoring two dairy farms (A and B) located in the Apulia Region. On each farm ten calves and ten heifers were observed monthly from May 1999 to February 2001 for clinical signs and blood parameters; antibodies against Babesia bigemina and Anaplasma marginale using an ELISA test were also monitored for the first eight months of the study. Totals of 28 and 14 cases of TBDs were observed in the complete herds of Farms A and B, respectively. Timing of disease appearance, categories of animals affected and changes in blood parameters are discussed.

Defining the states of consciousness

Consciousness remains an elusive concept due to the difficulty to define what has been regarded for many years as a subjective experience, therefore irrelevant for scientific study. Recent development in this field of research has allowed to provide some new insight to a possible way to define consciousness. Going through the extensive literature in this domain, several perspectives are proposed to define this concept. (1) Consciousness and Attention may not reflect the same process. (2) Consciousness during wake and sleep may not involve the same mechanisms. (3) Besides physiological states of consciousness, human beings can experience modified states of consciousness either by self-training (transcendental meditation, hypnosis, etc.) or by drug intake (hallucinogens, anaesthetics, etc.). Altogether, we address the question of a more precise terminology, given the theoretical weight words can convey. To this respect, we propose different definitions for concepts like consciousness, vigilance, arousal and alertness as candidates to separate functional entities.

Variation of visual detection over the 24-hour period in humans

A circadian rhythm for visual sensitivity has been intensively assessed in animals. This rhythm may be due to the existence of a circadian clock in the mammalian eye, which could account for fluctuating sensitivity to light over the day in certain species. However, very few studies have been devoted to the human visual system. The present experiment was designed to assess a possible rhythm of visual sensitivity using a psychophysical method over the whole 24h period. Twelve subjects underwent visual detection threshold measures in a protocol that allowed one point every 2h. The results show that the visual detection threshold changes over the 24h period, with high thresholds in the morning, a progressive decrease over the day and the early night, and an increase during the last part of the night. These data suggest that a circadian rhythm influences visual sensitivity to mesopic luminance in humans.

Visual resolution in humans fluctuates over the 24h period

The present experiment was designed to assess daily fluctuations of visual discriminability, a function reflecting the resolution power of the visual sensitivity by measure of a differential threshold. Sixteen subjects underwent a visual discrimination threshold task (using the constant method) in a protocol allowing one point every 2h over the 24h period. The results show that the visual discrimination threshold is low in the morning and increases progressively over the day, reaching a first peak at 22:00. During the night, the same pattern occurs, with low threshold levels at the beginning of the night and high levels at the end. This profile is quite different from that of detection threshold variations, suggesting that the two visual functions are under the control of different underlying mechanisms. Two interpretations could account for this discrepancy. The first relates to different oscillators in the eye for detection and discrimination. The second refers to a possible linkage of visual discriminability with the sleep-wake cycle since threshold measures were systematically low (i.e., high resolution power) after long sleep periods.

Diurnal pattern of luminance discrimination in humans

The visual discrimination threshold can be considered as an image of the resolution power of the visual system. Measured with a psychophysical method, it shows a diurnal pattern with a low threshold in the morning, i.e., high sensitivity and an increase in the afternoon that persists until the early evening.

Identification of Theileria buffeli/orientalis and Babesia bigemina in Apulian cattle using molecular techniques and study of changes in blood parameters

Recently several cases of theileriosis due to the haemoprotozoan Theileria buffeli/orientalis have been recorded in the Apulian region, Italy. In this area other tick-borne pathogens were usually identified such as Anaplasma marginale and Babesia bigemina. Outbreaks were recorded showing that these pathogens can be observed separately or in mixed infections. Sub-clinical cases and carrier animals were also previously identified. A lack of specific techniques could not rule out the presence of other haemoparasites such as T. annulata, B. divergens, B. bovis, Ehrlichia phagocytophila and E. bovis. Moreover little is known about the tick species involved in the dissemination of these diseases. Therefore more powerful techniques to specifically identify Theileria or Babesia species have been recently developed. A PCR technique and reverse line blotting (RLB) system to specifically identify six Theileria species and three Babesia species were used. T. buffeli/orientalis and B. bigemina were the only pathogens observed in the targeted animals. The authors also present some changes in blood parameters for the animals followed during this study.

Diurnal rhythmicity for visual sensitivity in humans?

Visual sensitivity rhythm has been assessed by several authors in animals. It shows an intrinsic circadian rhythm of some retinal mechanisms that could account for fluctuating sensitivity to light during the day in these species. However, very little is known concerning a possible circadian rhythm of visual sensitivity in humans. The present experiment was designed to assess a diurnal rhythm of visual sensitivity using psychophysical methods. Two different detection threshold measures (adaptive and constant methods) were applied on 7 highly entrained subjects. The results show a strongly increased visual detection threshold in the morning (8:00 h) in 4 of 7 subjects, followed by an important improvement at 10:00 h, after which time it remains almost constant whatever the method used. But 3 subjects had constant thresholds throughout the day. A "first session" effect as well as a "chronotype" effect were ruled out. The results are discussed in terms of a possible effect of sleep inertia, suggesting a long-lasting effect probably dependent on the type of task.

Implementation of napping in industry and the problem of sleep inertia

It seems reasonable to believe that in specific situations napping at the work place would be possible and used if authorized and encouraged. Very short naps could have very positive long-term effects on biological functions. Training someone to sleep for short periods appears feasible if there is a high motivation to do so. Sleep inertia can be considered as one of the main limiting factors in napping strategy. Sleep inertia depends on different factors such as sleep stage preceding the awakening, temporal placement of the nap, duration of nap and wakefulness preceding it, etc. The effects of sleep inertia might be different depending on the type of task, and a reactivation technique applied immediately after awakening may remove it. Despite the fact that its implementation in industry raises some practical issues, napping can be considered as a possible strategy to increase the vigilance level of night workers.

Disposition of antimony and aminosidine in dogs after administration separately and together: implications for therapy of leishmaniasis

The pharmacokinetic behaviour of aminosidine (15 mg kg-1) and antimony (25.65 mg kg-1 as N-methylglucamine antimoniate), administered subcutaneously either separately or together was studied on four dogs. The results demonstrated that antimony (Sb) did not significantly modify the kinetics of aminosidine (AM) but that the kinetic behaviour of the metal was markedly influenced by the antibiotic, as shown by the differences in mean residence time (MRT), elimination rate constant (Kel) and area under the curve (AUC) with and without the antibiotic (MRT[Sb] = 243.8 +/- 29.5 minutes, MRT[Sb+AM] = 1067.9 +/- 199.2 minutes; Kel[Sb] = 0.008 +/- 0.001 min-1, Kel[Sb+AM] = 0.0015 +/- 0.0003 min-1; AUC[Sb] = 21,024.6 +/- 4448.5 micrograms min ml-1, AUC[Sb+AM] = 130,478.5 +/- 30,481.7 micrograms min ml-1). The persistence of high serum concentrations of antimony when it was administered with aminosidine suggests that the therapeutic doses commonly used should be reduced and that the interval between administration should be increased to avoid the metal reaching toxic concentrations.

[Breast pathology in adolescence. Diagnostic problems]

Breast pathology, during adolescence, shows a typology like that in adults but with a completely different incidence. We observed 472 patients aged between 12 and 19 years in Senology Center of II Clinic of Obstetrics and Gynecology from 1984 to 1992. The most frequent pathologies diagnosed were: fibroadenomas (in the variety simple, phylloides, giant), cysts (simple and apocrine cysts); lower incidence for congenital anomalies, mastitis, mammary secretion caused by ductal hyperplasia or intraductal papilloma, lipoma. No incidence of cancer was detected. Echography was the principal diagnostic method for those patients who showed, at the clinical examination, a lump or palpable abnormalities. Mammography in this period does not affect the diagnoses and can be potentially harmful due to the exposure at X rays on such a sensible tissue.

Pharmacokinetics of N-methylglucamine antimoniate after intravenous, intramuscular and subcutaneous administration in the dog

The pharmacokinetic profile of antimony in dogs was defined by administering it intravenously, intramuscularly and subcutaneously as N-methylglucamine antimoniate at a dose of about 25.65 mg of antimony kg-1 bodyweight. The results showed a different half-life for the three routes of administration: 20.5, 42.1 and 121.6 minutes for the intravenous, intramuscular and subcutaneous routes, respectively; peak time values (Tmax) were also different for the intramuscular (90 to 120 minutes) and subcutaneous (210 to 240 minutes) injection. The apparent bioavailability of antimony was > 100 per cent for the intramuscular and 100 per cent for the subcutaneous routes. The data obtained showed a relevant difference in the behaviour of the drug in the dog in comparison to that in humans.

Interaction of the alerting effect of noise with partial sleep deprivation and circadian rhythmicity of vigilance

Only a few studies have been devoted to the interaction of noise with sleep deprivation and time of day. In a previous study we demonstrated that noise had an alerting effect on cognitive performance during the early night but not during the late night. However, it was not clear whether these different effects of noise were related to prior sleep debt or to time of day as both factors varied simultaneously. In the present experiment, we further studied this issue to identify which of these two factors was responsible for the noise effects. Analysis showed that, when performance was tested at different times with an equivalent prior sleep debt, noise improved speed of response at 0500 but not at 0800 at which variability of response time increased. Noise had no effect on errors. It is suggested that the effect of noise depends on the underlying arousal and raises arousal from its low level due either to time of day or to partial sleep deprivation.

Electroencephalogram and cardiovascular responses to noise during daytime sleep in shiftworkers

Intermittent noise occurring during sleep has been found to induce heart rate, peripheral vasomotor and electroencephalogram (EEG) changes. This study analysed these responses during the daytime and night-time sleep of shiftworkers doing a three shift system, to determine the influence of the inversion of the sleep-wake cycle on the sensitivity to noise. A group of 14 shiftworkers [aged 37 (SD 5) years] underwent an habituation daytime sleep, two experimental daytime sleeps and a night-time sleep. Traffic noises were presented during sleep [truck, 71 dB(A); motorbike, 67 dB(A); and car, 64 dB(A)] at a rate of nine each hour. The EEG measurements of sleep, electrocardiogram and finger pulse amplitude were recorded continuously. The results were expressed by computing the percentage of observed cardiac response (%HRR) and vasoconstrictive response (%FPR), magnitude of heart rate variation (heart rate response; HRR), percentage of reduction of the digital blood flow (finger pulse response, FPR), cardiac cost (CC = % HRR x HRR) and vasomotor cost (VC = % FPR x FPR). The results showed that, compared to night-time sleep, there was change in the structure of daytime sleep, that is an increase in slow wave sleep (SWS), especially stage 4 sleep decrease of stage 2 and rapid eye movement (REM) sleep latencies, and an earlier SWS and REM sleep barycentric point. During daytime sleep the % FPR was significantly smaller in SWS than in stage 2 or REM sleep. Large differences were observed in % HRR, HRR and CC between daytime sleep stages (SWS less than stage 2 less than REM sleep).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of noise on sleep inertia as a function of circadian placement of a one-hour nap

The purpose of the present study was to analyse the arousing effects of noise on sleep inertia as a function of circadian placement of a one-hour nap. In a first experiment, we measured the effects of sleep inertia in a neutral acoustic environment after a one-hour nap placed either at 0100 or 0400 on response time during a spatial memory test. In a second experiment were analysed the effects of an intense continuous noise on sleep inertia. The results showed that noise produced a total abolition of sleep inertia after an early nap (0000 to 0100). This may be due to the arousing effect of noise; however, results are less clear after a late nap 0300 to 0400 as noise seems to be ineffective. This result is discussed in terms of either a function of time-of-day effect or of prior sleep intensity. Moreover, our data suggest a possible interaction of noise with partial sleep deprivation leading to a slight deleterious effect those subjects who did not sleep at all.

[The breast in adolescence. Physiopathological and clinical considerations]

Mammary pathology, during adolescence, is an uncommon event and generally not very serious. During this growth period the different tissue mammary components are influenced by metabolic and hormonal stimulus in a proliferative and differentiative sense. In this growth period an efficient clinical approach is really necessary and it must not be only confined to senologic control, but inserted in the traditional semeiotics of a teenage patient, associated with a practice of self-palpation from the conclusive phases of the mammary development.

Cardiovascular responses and electroencephalogram disturbances to intermittent noises: effects of nocturnal heat and daytime exposure

During sleep, in thermoneutral conditions, the noise of a passing vehicle induces a biphasic cardiac response, a transient peripheral vasoconstriction and sleep disturbances. The present study was performed to determine whether or not the physiological responses were modified in a hot environment or after daytime exposure to both heat and noise. Eight young men were exposed to a nocturnal thermoneutral (20 degrees C) or hot (35 degrees C) environment disturbed by traffic noise. During the night, the peak intensities were of 71 dB(A) for trucks, 67 dB(A) for motorbikes and 64 dB(A) for cars. The background noise level (pink noise) was set at 30 dB(A). The noises were randomly distributed at a rate of 9.h-1. Nights were equally preceded by daytime exposure to combined heat and noise or to no disturbance. During the day, the noises as well as the background noise levels were increased by 15 dB(A) and the rate was 48.h-1. Electroencephalogram (EEG) measures of sleep, electrocardiograms and finger pulse amplitudes were continuously recorded. Regardless of the day condition, when compared with undisturbed nights, the nocturnal increase in the level of heart rate induced by heat exposure disappeared when noise was added. Percentages, delays, magnitudes and costs of cardiac and vascular responses as well as EEG events such as transient activation phases (TAP) due to noise were not affected by nocturnal thermal load or by the preceding daytime exposure to disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)

Ivermectin against larval stages of Dirofilaria repens in dogs

The prophylactic efficacy of ivermectin against Dirofilaria repens infections in dogs was investigated. A first trial was carried out on 15 dogs exposed to four inoculations of L3 larvae at 15-day intervals and treated, in groups of five, with 0, 6 or 12 micrograms/kg body weight of ivermectin given per os 30 and 60 days after the first inoculation. Necropsy, performed about 9 months later, revealed that worm burdens were reduced by 86.6 and 92.8% for the 6 and 12 micrograms/kg dose levels, respectively. In a second trial with an otherwise identical protocol, a dose rate of 24 micrograms/kg of ivermectin was tested in 12 dogs. Only one of the six treated dogs was found worm free at necropsy. The worm burden was reduced by 87.9% in treated animals as opposed to controls. A lengthening of the prepatent periods, which might be considered dose related, was apparent in all treated groups. Ivermectin was not completely effective in preventing establishment of experimental infections with D. repens in dogs.

[Echinococcus granulosus infection in urban areas]

In a previous survey, carried out in 100 dogs in Rome by Tassi and Widenhorn (1977), two animals, which always lived in the urban area, were found infected by Echinococcus granulosus. An urban infection was therefore hypothized. During a following experiment 6 three-month old Beagle dogs were fed for nine months with raw meat sold in the butcheries of Rome as "food for pets". Two dogs of the same breed and origin were fed for the same period with canned food and were kept as control animals. At the end of the experiment three of the six dogs were found infected by E. granulosus, while the renmant three and the two controls resulted negative. An additional similar trial was carried out in Bologna. Three dogs were fed for seven months with the same kind of raw meat sold in three butcheries of Bologna, and a fourth dog was kept as control. At the end of the seven months also one of the three dogs was found infected by E. granulosus. These results seem to confirm the hypothesis of an urban infection by E. granulosus in dogs. Various possibilities of contamination of raw meat sold in butcheries as food for animals are discussed.